Dangers of the Flight Deck - Part 1

• It's been said that working on the flight deck of a U.S. Navy aircraft carrier is one of the most dangerous jobs in the world. Well, that's true. But what most people don't know is that it's pretty scary, too, - at least at first. One thing for certain is that there are many things to watch out for – things that can kill you in a blink of an eye. There's a saying to "always be aware of your surroundings." That statement couldn't be any farther from the truth.

• Before you're even allowed to set foot on the flight deck of an aircraft carrier, you must stay in the ship's crow's nest for 3 days. There, you watch flight operations just to get an idea of what's going on and how things operate. After that, you must become flight-deck certified. To do this, you have to spend a week attached to the hip of someone who is qualified. Finally, only when you're qualified, can you go out on the flight deck on your own. This is when things can get real interesting and a little scary.

• When you're out on the flight deck alone, there are a lot of things to watch out for. There's a reason why you're given all kinds of gear to wear, especially head gear and goggles. Your head gear is called a cranial and has goggles attached. Always, that's the first thing you put on before even stepping foot on the flight deck. You also have to wear long sleeve shirts, pants, and a flight jacket at all times. All of this clothing is for your protection.

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Dangers of the Flight Deck - Part 2

• Your flight jacket is a survival jacket if you were to ever fall off the flight deck of a U.S. Navy aircraft carrier. It has a strobe light that flashes at night so other sailors can know where you are. Your flight jacket also has a bladder that fills up with air when you hit the water. If that bladder were to fail, there's a tube that you can use to manually fill up the bladder. Just blow into it. The flight jacket also has dye packs so that if you were to fall off the ship during the day, people can find you.

• The heat from the exhaust of a jet isn't the only risk from the jet. If you're not paying attention to what's going on around you and a jet turns, the force of that jet will knock you down and send you for a ride. It can also blow you off the side of the ship. When you're blown across the flight deck, you get road rash from the "non-skid," the substance put over the deck to prevent slipping in case of oil or gasoline spills. Being blown over the side of the ship is more dangerous since there's always the chance the fall could kill you by breaking your neck. You could also get sucked under from the screws of the ship and then chopped up by those screws.

• When aircraft land on the carrier, there are four steel cables that catch the plane as it lands. These are the arresting cables. Whenever a jet is landing, you want to stay away from the designated area because if you're caught in that area, that wire - with all the force pulling on it from the jet - will cut you in half. There are elevators, too, four to be exact, on the flight deck. There are also supposed to be people and other safety precautions around to make sure nobody falls, but human error occurs. So if someone isn't paying attention, especially at night, then you can have a nasty fall.

• Even when jets aren't moving around, the flight deck is a dangerous place because something is always going on. For example, there are blast shields that raise-up to deflect the after-burn when a jet takes off. Well, a friend of mine worked on them doing routine maintenance checks. The shield was raised partially so he could work. For some reason, the hydraulics on the shield failed and it fell back down. My friend was lucky enough for the shield not to land on him, but not lucky enough to get completely out of the way. One of his fingers was partially torn off.

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Piper Cubs, Birds of War, and Antique Airplanes

Aerospace engineers and aviation enthusiasts can view some of the world's greatest aircraft on-line. Ron Darner, a longtime CR4er who is also the newsletter editor for Chapter 320 (Watertown, Wisconsin) of the Experimental Aircraft Organization (EAA), has offered to take us on a tour. Today, let's visit the Piper Cub Forum, Warbird Alley, and a great gallery of photos from Darrell Graves.

Piper Cub Forum

• The Piper Cub was a small, lightweight aircraft built by the Piper Aircraft Company; its predecessor, the Taylor Aircraft Company; or its successor, the New Piper Aircraft Company.
  
• Piper Cub Forum covers not just the original Piper Cubs, but all of the derivatives (L4 Grasshopper, PA-11 Cub Special and PA-18 Super Cub) along with the look-alikes of today.
• There's a lot of information on-hand. Some is for all tail-dragger pilots, and not just for those flying the immortal Cub.

Warbird Alley

• Warbird Alley describes many different military aircraft and arranges them into categories such as trainers, bombers, and transports.
  
• This page provides links to a separate page for each aircraft. There are also photos, flying reports, links to external Web sites, and a wealth of additional information.
  
• Warbird Alley is a great place for anyone with a casual interest in the subject. It's also a treasure trove for those who are ready to buy and restore warbirds, or who plan to write a book on the subject.
  
• Although the Web site specializes in "birds which have at least one still-operating example, somewhere", it also lists some warbirds where only museum-owned aircraft are still in existence.

Darrel Graves

• Darrell Graves has a nice gallery of photos of mostly vintage and antiques airplanes at.
• Many of the specific examples are ones we've seen at Oshkosh, or at Sun-and-Fun or other fly-ins, but there are some actual vintage photos, such as the Northrup Gamma seen here, or the Boeing Monomail seen there.

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Flip of a Switch May One Day Quiet Jet Engines

• Jet engines may run quieter in the future.
  Researchers have developed a silencer technology that creates electrical arcs to control turbulence in engine exhaust airflow -- the chief cause of engine noise. The university has applied for a patent on the design.
  With the flip of a switch, pilots could turn the silencers -- called plasma actuators -- on and off, reducing noise around commercial airports or military airstrips.
• Jet engines may run quieter in the future, with technology developed at Ohio State University.
• Researchers here have developed a silencer technology that creates electrical arcs to control turbulence in engine exhaust airflow -- the chief cause of engine noise. The university has applied for a patent on the design.
• With the flip of a switch, pilots could turn the silencers -- called plasma actuators -- on and off, reducing noise around commercial airports or military airstrips, said Mohammad Samimy, professor of mechanical engineering.
• He and his colleague, Igor Adamovich, associate professor of mechanical engineering, demonstrated the technology in a series of laboratory tests. They used laser light to illuminate a simulated engine exhaust stream, and studied how different arrangements of actuators affected the flow.
• They tested the actuators using two types of air streams, one simulating the exhaust from a commercial aircraft, and another simulating that of a high-speed military aircraft. Typical large commercial aircraft, such as the Boeing 747, fly at mach 0.85, or 0.85 times the speed of sound, while modern military aircraft can top mach 2.
  The most important factor in silencing an aircraft during takeoff -- when the jet engine is the loudest -- is controlling exhaust airflow, Samimy said. The high-speed airflow provides thrust for the plane, and also creates most of the noise.
• The tests showed that the plasma actuators succeeded in manipulating turbulence structures in the airflow.
• All jet aircraft could benefit from the technology, Samimy said.
• Until recently, noise was a problem only for commercial airports, which are often surrounded by residential areas. But as populations spread around the United States, military airports have also started to feel pressure to reduce noise heard by neighboring communities, he explained.
• The most important factor in silencing an aircraft during takeoff -- when the jet engine is the loudest -- is controlling exhaust airflow, Samimy said. The high-speed airflow provides thrust for the plane, and also creates most of the noise.
• ''One has to reduce the noise while not adversely affecting the thrust -- that is the challenge. When the development of the actuators is complete, they will meet the challenge,'' he said.
• Samimy studies turbulence as part of his work with fluid dynamics, one of the most complex areas of study in science and engineering. Flow control is a multidisciplinary subject, which draws researchers from various engineering disciplines such as mechanical, aeronautical, and electrical.
• By analyzing images of fluid flows, Samimy and his colleagues can gather a wealth of information which can be used in controlling the flow. For instance, they can tune the newly developed plasma actuators to match certain frequencies in the flow, and optimize noise reduction.
• This project grew out of Samimy's work for NASA in the 1990s. There he worked on structural modifications at the trailing edge of the exhaust system called tabs or chevrons -- zigzag-shaped cutouts at the nozzle exit that introduced longitudinal turbulence structures into the exhaust flow and so affected the mixing and noise characteristics of the engine. Some of the most recent aircraft engines contain chevrons.
• While chevrons reduce noise, they lower fuel efficiency. Chevrons are only needed during takeoff and landing, but they are permanent fixtures of the engine and cannot be disengaged at cruise altitude to increase fuel efficiency.

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First Private Manned Mission to Space

• The world witnessed the dawn of a new space age today, as investor and philanthropist Paul G. Allen and Scaled Composites launched the first private manned vehicle beyond the Earth's atmosphere. The successful launch demonstrated that the final frontier is now open to private enterprise.
  Under the command of test pilot Mike Melvill, SpaceShipOne reached a record breaking altitude of 328,491 feet (approximately 62 miles or 100 km), making Melvill the first civilian to fly a spaceship out of the atmosphere and the first private pilot to earn astronaut wings.
  
• The world witnessed the dawn of a new space age today, as investor and philanthropist Paul G. Allen and Scaled Composites launched the first private manned vehicle beyond the Earth's atmosphere. The successful launch demonstrated that the final frontier is now open to private enterprise.
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• Under the command of test pilot Mike Melvill, SpaceShipOne reached a record breaking altitude of 328,491 feet (approximately 62 miles or 100 km), making Melvill the first civilian to fly a spaceship out of the atmosphere and the first private pilot to earn astronaut wings.
• This flight begins an exciting new era in space travel,'' said Paul G. Allen, sole sponsor in the SpaceShipOne program. ''Burt Rutan and his team at Scaled Composites are part of a new generation of explorers who are sparking the imagination of a huge number of people worldwide and ushering in the birth of a new industry of privately funded manned space flight.''
• The historic flight also marks the first time an aerospace program has successfully completed a manned mission without government sponsorship. ''Today's flight marks a critical turning point in the history of aerospace,'' said Scaled Composites founder and CEO Burt Rutan. '' We have redefined space travel as we know it.''
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• ''Our success proves without question that manned space flight does not require mammoth government expenditures,'' Rutan declared. ''It can be done by a small company operating with limited resources and a few dozen dedicated employees.''
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• A large crowd watched the momentous flight live from the grounds of the Mojave Airport, joining millions of others around the world who tuned in by television, radio, and the internet. Dignitaries attending the event included U.S. Representative Dana Rohrabacher, the Commanding Officer of Edwards Air Force Base, General Pearson and the China Lake Naval Air Warfare Center, Admiral Venlet; former astronaut Buzz Aldrin, and Konrad Dannenberg, one of Werner Von Braun's lead scientists on this country's original space development effort. Hundreds of media representatives were also on hand to record history in the making.

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Coal source of jet fuel for next generation aircraft

• New fuel for the next generation of military aircraft is the goal of a team of Penn State researchers who are demonstrating that jet fuel can be made from bituminous coal. "On a pilot scale, we have produced thermally stable coal-based jet fuel," says Dr. Harold H. Schobert, professor of fuel science and director of Penn State's Energy Institute. "This coal-based fuel can absorb significant amounts of heat and remain stable to 900 degrees Fahrenheit." The new fuel will not decompose at high temperatures to create the deposits of carbon, which foul valves, nozzles and other engine parts.
• New fuel for the next generation of military aircraft is the goal of a team of Penn State researchers who are demonstrating that jet fuel can be made from bituminous coal.
• "On a pilot scale, we have produced thermally stable coal-based jet fuel," says Dr. Harold H. Schobert, professor of fuel science and director of Penn State's Energy Institute. "This coal-based fuel can absorb significant amounts of heat and remain stable to 900 degrees Fahrenheit."
• The new fuel will not decompose at high temperatures to create the deposits of carbon, which foul valves, nozzles and other engine parts. The fuel will be provisionally designated jet propulsion 900 or JP900 because of this high temperature stability. The researchers are designing the fuel for the new generation of high performance engines in aircraft such as the F35 joint strike fighter and the U.S. Air Forces' VAATE program ? versatile, affordable, advanced turbine engines. However, according to the researchers, it may be possible to use this fuel in conventional jet engines in current aircraft.
• The front portion of a jet engine is an air compressor and the new engines compress air at higher and higher pressures generating larger amounts of heat. The outside air is not sufficient as a cooling medium, so the designers use the fuel itself as a heat sink, so high temperature stability is necessary.
• "While power generation will remain the mainstay of coal use for many decades, coal does supply a molecular structure that has properties necessary for making high-temperature stable fuel," says Schobert.
• Schobert; Suchada Butnark, former graduate student in fuel science; and Leslie R. Rudnick, senior scientist at the Energy Institute, worked on two processes to create JP900 from coal-based materials. One method relies on bituminous coal becoming fluid when heated. The researchers mixed bituminous coal with decant oil, a byproduct of petroleum refining, at normal pressures. When heated, the mixture becomes fluid and the liquid portion distills off and is collected as JP900. The remaining solid is coke, a valuable byproduct for making anodes for aluminum smelting or in making graphite.
• "This process is a variant of a standard process used in petroleum refining," says Schobert. "We would really just need a mixer for the two components and then the process could be done in normal refinery operations."
• The second process uses light cycle oil, another petroleum byproduct, and coal-derived refined chemical oil, a byproduct of the coke industry. The researchers mix the two components and add hydrogen. When distilled, jet fuel comes off as a distillate.
• The Penn State researchers believe that they can carry out both processes in existing refineries. They plan in the next year to test the fuel in a jet engine at Wright Patterson Air Force base. Currently, the researchers are producing JP900 in 55-gallon barrel lots, but they hope in the future to test manufacturing with a run at United Refining in Warren, Pa.
• The researchers are also working with the Air Force to develop an official specification for JP900. "Without a specification, no one will put this fuel in an engine," says Schobert.
• One potential benefit with manufacturing these fuels in existing refineries is that small amounts of the leftover components will feed into various portions of the petroleum stream. The lighter portions will go to the pool of chemicals that make gasoline and the heavier ones go to the diesel or fuel oil streams.
• "The inclusion of coal-based compound in the petroleum steam will probably be beneficial in making gasoline and probably will not make any difference at all in the fuel oil stream," says Schobert. "What we do not know is how it will affect the diesel stream."
• In addition to its high temperature properties, JP900 has a 10-degree Fahrenheit lower cloud point ? the temperature at which a cloud forms over a liquid. This is a better cold weather fuel than either the Jet A or JP8 currently in use.
• These coal-derived fuels also have no ash and very low sulfur. Refined chemical oil, derived from coal, has already had the ash removed. In the decant oil process, the coal would need to be pre-cleaned but would also produce a low-ash coke byproduct.
• When it comes to coal, sulfur is often the most troublesome pollutant, but these processes can be as low sulfur as three parts per million, depending on the original sulfur content of the coal and the amount of hydrogen used. For higher sulfur coal, more hydrogen will allow fuels that are still low sulfur.

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Pentagon Plans Heavy Investment in UAV Development

• The Defense Department today unveiled a billion dollar roadmap for unmanned aerial vehicles during the next 25 years. Plans call for developing joint interoperable UAVs that are capable of everything from surveillance to air strike. "The roadmap provides those high priority investments necessary to move UAV capability to the mainstream," said Dyke Weatherington, deputy of the UAV Planning Task Force in the Office of the Secretary of Defense, at a DoD press briefing today. "The potential value UAVs offer range across virtually every mission area and capability of interest to DoD. The roadmap identifies those key technology areas that we think are right for investment."
• The Defense Department today unveiled a billion dollar roadmap for unmanned aerial vehicles during the next 25 years. Plans call for developing joint interoperable UAVs that are capable of everything from surveillance to air strike.
• "The roadmap provides those high priority investments necessary to move UAV capability to the mainstream," said Dyke Weatherington, deputy of the UAV Planning Task Force in the Office of the Secretary of Defense, at a DoD press briefing today. "The potential value UAVs offer range across virtually every mission area and capability of interest to DoD. The roadmap identifies those key technology areas that we think are right for investment."
• The Pentagon has made UAV weapon systems a priority. Defense Secretary Donald Rumsfeld, who strongly supports the UAV program, has pushed UAVs as one way to transform the military.
• Today, about 90 UAVs support military operations around the world, and the department has them standing by for potential use over Iraq.
• By 2010, according to the roadmap report, DoD hopes to increase its UAV inventory to about 350. And the department plans to increase that to more than a thousand in the outyears, according to Weatherington.
• From 1991 to 1999 the Pentagon invested about $3 billion in UAV projects. That is projected to rise to $10 billion from today through 2010, according to the latest DoD Unmanned Aerial Vehicles Roadmap 2002-2027 report.
• The Air Force's Predator UAV proved its military capability flying reconnaissance missions in Bosnia, and was credited with taking out one of al Qaeda's top lieutenants in Afghanistan with a Hellfire missile.
• Besides Predator, the military services are developing other UAV platforms. For example, the Air Force has another UAV called Global Hawk. The system is completely computer-operated and can be used for long-term surveillance. The high-flying Global Hawk currently carries photo reconnaissance equipment, but production versions of the system will carry electronic intelligence gathering materials. The Global Hawk can stay airborne for 32 hours.
• The Army has developed the Shadow 200 tactical UAV. The Army also has the Hunter UAV, and both are primary surveillance UAVs and relay video in real time.
• Meanwhile, the Marine Corps has developed Dragon Eye, a small, hand-launched UAV that can give leaders a snapshot of the battlefield, and it plans to make improvements to the Pioneer UAV developed by the Navy. The Pioneer was used in the 1991 Gulf War.

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Aircraft technology helps diagnose artificial hip, knee problems

• To assess the wear and tear on jet engine parts, mechanics used an old technology called ferrography to run the aircraft's lubricating fluid through a magnetic device to separate out metal shavings and other ferrous engine debris. A University of Rhode Island researcher uses a similar process to assess the wear and tear on artificial hip and knee joints so patients can reduce the number of follow-up surgeries they must undergo or reduce the time spent in revision surgery. From the University of Rhode Island :
• Aircraft technology helps diagnose artificial hip, knee problems
• KINGSTON, R.I. (February 20, 2003) To assess the wear and tear on jet engine parts, mechanics used an old technology called ferrography to run the aircraft's lubricating fluid through a magnetic device to separate out metal shavings and other ferrous engine debris. A University of Rhode Island researcher uses a similar process to assess the wear and tear on artificial hip and knee joints so patients can reduce the number of follow-up surgeries they must undergo or reduce the time spent in revision surgery.
• Donna Meyer, an assistant professor of mechanical engineering, anticipates using her research to create a "wear atlas" that can be used by orthopedic surgeons as a diagnostic tool. She said the atlas could be used to help identify the potential problems that patients are having with their implants prior to revision surgery.
• Most artificial hips consist of a polyethylene socket and metal ball or metal-on-metal combinations that are connected to adjoining bones with screws or cement. Total knee replacements are made of similar materials. Over time as the ball, socket and bone rub against each other, tiny debris is produced and settles between the bone and the implant interface, discouraging the much needed growth of bone around the prosthesis. This contributes to the loosening and separation of the interface, which necessitates revision surgery to repair it.
• "Polyethylene wear debris can be a significant problem for patients because a loosened joint can cause great discomfort," said Meyer, a Cranston resident. "If we can determine the number and size of wear debris contained in a patient's synovial fluid, and also look at the ratio of polyethylene to other constituents like metal, bone, and cement particles, we can create a tool to assist in diagnosing the problem with the implant before surgery is necessary. Ultimately we would like to minimize the number of revision surgeries that patients face, or at least minimize the amount of time spent in surgery for additional operations."
• Meyer takes a sample of a patient's synovial fluid ? " it's a large component of the lubricating fluid around your knee or hip," she said ? and uses a process called bio-ferrography to capture the tiny particles of polyethylene, metal, bone and cement using a very strong magnet. Since most of the wear debris isn't magnetic and therefore wouldn't be collected by the device, she adds to the fluid sample a magnetic compound that binds to the non-magnetic particles.
• "We need to capture every tiny particle in each sample to make sure the atlas is accurate," said Meyer, whose research is funded by the National Science Foundation and the Rhode Island Biomedical Research Infrastructure Network.
• Meyer's interest in this research was sparked when she was a graduate student at Rensselaer Polytechnic Institute studying the lubrication of artificial hip joints. She talked to the chief of orthopedic surgery at the time at Albany Medical Center, who told her of his interest in bio-ferrography. She's been researching the subject ever since.
• Once she perfects the technique for collecting the wear debris, she will begin creating the atlas. Meyer said the atlas will be designed so doctors can easily compare a patient's age, activity level, implant type and time since implantation with the size and composition of the wear debris to quickly determine which part of the implant is the likely cause of the problem. For example, small particles are more likely to lead to implant loosening. Large pieces of debris, on the other hand, contribute greatly to the wear volume, but it is not certain how much it contributes to implant loosening, if at all.

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Robo Gung-Ho

• "Gung ho" means "work together," and that's what Texas-based Geneva Aerospace, Inc. has got its flying robots doing. Using technology developed with the support of the Office of Naval Research, Geneva Aerospace showed that a single human operator can control three unmanned aerial vehicles (UAVs) at once. The flight tests were conducted between January 7 and 17 of 2003 at Desert Center, California.
• "Gung ho" means "work together," and that's what Texas-based Geneva Aerospace, Inc. has got its flying robots doing. Using technology developed with the support of the Office of Naval Research, Geneva Aerospace showed that a single human operator can control three unmanned aerial vehicles (UAVs) at once. The flight tests were conducted between January 7 and 17 of 2003 at Desert Center, California.
• The culmination of research and development funded by ONR's "Autonomous Operations Future Naval Capability" program and the Air Force Research Laboratory, the tests showed that advanced yet affordable technologies can give a non-aviator the ability to coordinate several UAVs during a mission. The technologies include flight controls, communications, and human-system interfaces. The approach enables the UAVs to operate with variable degrees of autonomy. The project's ultimate goal is to develop an integrated system architecture that significantly reduces the logistical burden current UAVs impose on American warfighters.
• Geneva Aerospace integrated its Variable Autonomy Control System (VACS) with its Dakota UAVs for the tests. VACS is an autonomous and semi-autonomous control system that uses advanced flight controls technologies to support UAV operation at various levels of control autonomy, from simplified manual control to fully autonomous mission execution. Geneva produces the variable autonomy control system and offers the system as an off-the-shelf UAV integrated flight control solution. The Dakota UAV has a 16-foot wingspan, and weighs 200 pounds at takeoff. It's manufactured at Geneva's Logan, Utah facility and used by ONR and other organizations as a testbed for autonomous operations technology demonstrations.
• The demonstrations consisted of dynamically controlling three UAVs as they performed militarily relevant and representative coordinated reconnaissance and combat strike sorties. The demonstration began with the UAVs being launched by a Launch and Recovery Authority and directed to an appropriate mission hand over point. A single operator then took positive control of the UAVs and issued the necessary dynamic guidance and control commands to accomplish the representative reconnaissance/strike mission. This Mission Controller was a non-rated UAV operator. Upon completion of the representative mission, the Mission Controller directed return of the UAVs to a designated recovery point where the Launch and Recovery Authority took positive control for the UAV approach and landing phase.

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From the bone of a horse, a new idea for aircraft structures

• The horse, a classic model of grace and speed on land, is now an unlikely source of inspiration for more efficient flight. So says a group of University of Florida engineers who have recreated part of a unique bone in the horse's leg with an eye toward lighter, stronger materials for planes and spacecraft.

• The third metacarpus bone in the horse's leg supports much of the force conveyed as the animal moves. One side of the cucumber-sized bone has a pea-sized hole where blood vessels enter the bone. Holes naturally weaken structures, causing them to break more easily than solid structures when pressure is applied. Yet while the third metacarpus does fracture, particularly in racehorses, it doesn't break near the hole - not even when the bone is subjected to laboratory stress tests. UF engineering researchers think they've figured out why - and they've built and are testing a plate that mimics the bone's uncanny strength in a form potentially useful for airplanes and spacecraft.
• From the University of Florida:
• From the bone of a horse, a new idea for aircraft structures
• GAINESVILLE, Fla. --- The horse, a classic model of grace and speed on land, is now an unlikely source of inspiration for more efficient flight.
• So says a group of University of Florida engineers who have recreated part of a unique bone in the horse's leg with an eye toward lighter, stronger materials for planes and spacecraft.
• The third metacarpus bone in the horse's leg supports much of the force conveyed as the animal moves. One side of the cucumber-sized bone has a pea-sized hole where blood vessels enter the bone. Holes naturally weaken structures, causing them to break more easily than solid structures when pressure is applied. Yet while the third metacarpus does fracture, particularly in racehorses, it doesn't break near the hole - not even when the bone is subjected to laboratory stress tests.
• UF engineering researchers think they've figured out why - and they've built and are testing a plate that mimics the bone's uncanny strength in a form potentially useful for airplanes and spacecraft.
• "Holes are a classic source of failure in engineered structures, but nature has found a way around that in this bone," said Andrew Rapoff, an assistant professor of aerospace and mechanical engineering and the lead researcher on the project. "We're mimicking nature's solution."
• The researchers have published at least five papers on their work, which they've been conducting for three years with the assistance of a $675,000 NASA grant. Most recently, they were invited to submit a paper to a special issue of the Journal of Biomechanics to appear next year.
• Airplanes have holes for wiring, fuel and hydraulic lines. Similar holes are common in boats, buildings, automobiles, homes and virtually any other structure that has functions beyond simply sheltering or containing something. Engineers typically compensate for the weaknesses caused by these holes by increasing the thickness of the material around them. In a classic example, ship builders add extra material around portholes in hulls to guard against structural weakness or failure, said Stephen Cowin, a distinguished professor of mechanical engineering and director of the New York Center for Biomedical Engineering at The City College of New York.
• The shortcoming of that approach is that it adds weight, a problem for airplanes and spacecraft that need to be as light as possible, Rapoff said. The rule of thumb in the aerospace industry is that reducing the weight of a plane by one pound saves 10 pounds of fuel, so techniques to maintain aircraft strength without adding weight are sorely needed. This is true particularly for spacecraft that have extremely high launch costs, he said.
• The engineers analyzed the structure of the horse bone around its hole - or foramen - with microscopy and microradiography, techniques that render the details of its microscopic composition. They converted the resulting information into equations describing the bone's mechanical properties - for example, converting the bone's mineral density and porosity into an equation describing its stiffness. The engineers then developed a computer model that mimics the bone's behavior under stress, proving the model's accuracy by testing it against laboratory tests of the bone.
• The upshot of their analyses: The bone was configured in such a way that it pushed the highest stresses away from the foramen into a region of higher strength. For example, the position of its osteons, or structural units created when the bone first developed, routed stress around the foramen.
• The engineers used their analyses and computer model to create a "biomimetic plate," with a hole surrounded by several different grades of polyurethane foam to mimic the compositional structure of the bone near the foramen. Biomimetics describes the increasingly common engineering trend of mimicking natural solutions in manmade materials.
• The researchers tested the plate by placing it across two upright pillars and weighing it down, comparing the results with those from an identical test of a plate with a drilled hole without the foam stabilizer. It took twice the weight to break the biomimetic plate. Moreover, when it did finally break, the fracture did not go through the hole as occurred with the plate with the drilled hole.
• UF master's student Barbara Garita has recently taken the work a step further. Garita, one of several master's and doctoral students working on the project, has demonstrated the foramen in the natural bone is stronger than a drilled hole when thin sections of the bone are subjected to repeated stress over time. The engineering researchers plan to subject the biomimetic plate to similar cyclical stress conditions that are common in real life, occurring, for example, when a boat pounds waves or an airplane experiences repeated turbulence. "We'll solve many problems using this bone," Garita said.
• Rapoff and Cowin said applications for the research will grow as manufacturing techniques to create products composed of different grades of material improve.
• "We'll be able to manufacture materials with modern machinery in a very elegant way that allows us to vary the properties the way that nature does," Cowin said, adding that the University of Florida researchers are the only researchers he's aware of who are examining the problem using a biomimetic approach.
• Basic versions of so-called "functionally graded materials" already are used in airplanes and spacecraft, for example, in wing flaps made from material arranged in a honeycomb pattern overlaid with metal, Rapoff said. Future versions will replace the honeycomb pattern with continuous gradations of differently composed materials. If the flap or other elements of the structure built with such materials need holes, it would make sense to draw on the UF research on the horse bone foramen, he said.
• "We've told the world 'this is how you design near holes for minimum weight and maximum strength,'" he said. "Now it's up to the designers and manufacturers to make these sorts of things."

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GPS takes piloting to new level of accuracy

• NASA has developed a way to pilot aircraft independent of local navigational aids, infrastructure and even good ol' landmarks. The NASA Global Differential GPS system at NASA's Jet Propulsion Laboratory has demonstrated the ability to achieve real-time aircraft positioning accuracy of 10 centimeters horizontally and 20 centimeters vertically, anywhere in the world. Think of it this way: Using the NASA system, a pilot could remotely navigate an unmanned aircraft from, say, Atlanta, Georgia and have it land within three inches of its target in Tokyo, Japan.
• NASA Navigation Work Yields Science, Civil, Commerce Benefits
  October 14, 2002
• NASA researchers have demonstrated the ability to very precisely navigate airplanes in real time, anywhere in the world, independent of local navigational aids or infrastructure. The breakthrough will not only benefit scientists, but promises to extend precision navigation to infrastructure-poor areas of the world, potentially enhancing aviation safety in these areas.
• Ron Muellerschoen, lead architect of the NASA Global Differential GPS system at NASA's Jet Propulsion Laboratory, Pasadena, Calif., has demonstrated the ability of the system to achieve real-time aircraft positioning accuracy of 10 centimeters (3.9 inches) horizontally and 20 centimeters (7.9 inches) vertically, anywhere in the world-a factor of 10 improvement over current autonomous navigation systems. The system relays precise, real-time navigation data to specially equipped aircraft. The JPL team's results were presented recently at the Institute of Navigation Global Positioning System (GPS) 2002 Exhibit in Portland, Ore.
• Although developed to improve the accuracy, efficiency and timeliness of Earth science missions, the technology's by-products may also include numerous civil and commercial applications in such areas as aviation safety, marine operations, land management, transportation and agriculture, said Dr. Yoaz Bar-Sever, the principal investigator for NASA's Global Differential GPS system at JPL. "Civil and commercial navigation services, currently only available within Earth's infrastructure-rich regions, could now be extended to any part of the world without lowering performance and with little to no marginal cost," he said.
• Within the field of Earth science, Bar-Sever said the technology would be used to develop better exploration techniques for Earth observing instruments flying aboard aircraft and spacecraft. "The ability of Earth science instruments to precisely and autonomously know their position and velocity in real time is critical to many Earth observing applications, including monitoring and responding to natural hazards such as earthquakes, volcanoes and hurricanes," he said.
• JPL's Airborne Synthetic Aperture Radar Group has already used the precise real positioning from the Global Differential GPS system to improve the resolution of Earth images from NASA's aircraft-based Airborne Synthetic Aperture Radar instrument, said Group Supervisor David Imel. Imel envisions even greater use for the system in the near future. "For missions where an aircraft must fly exactly the same flight profile repeatedly, in order to sense subtle changes in the Earth from one flight to the next, the need for the extremely precise navigational accuracy that this system provides is critical," he said.
• In space, precise onboard knowledge of position will improve the efficiency of a spacecraft's onboard data processing and reduce the time needed to transmit data to the ground. Bar-Sever and his team have already conducted successful demonstrations of decimeter-level real-time satellite positioning using data from NASA's Jason-1 spacecraft and the Argentinean Satelite de Aplicaciones Cientificas-C satellite. The team is currently developing a prototype payload to be flown aboard a spacecraft.
• The NASA Global Differential GPS system flight demonstrations were conducted over the United States and Greenland in February through September 2002 aboard a NASA Airborne Synthetic Aperture Radar DC-8 aircraft from NASA's Hugh L. Dryden Flight Research Center, Edwards, Calif., and a NASA P-3 aircraft from NASA's Wallops Flight Facility, Wallops Island, Va.
• Developed and operated by JPL since 1999 for NASA's terrestrial, airborne, and spaceborne science applications, NASA's Global Differential GPS system provides end-to-end capabilities for autonomous, real-time orbit determination and positioning at unprecedented levels of accuracy and availability. The system processes real-time GPS data from a global network of more than 30 dual-frequency GPS ground sites. It is the only system in existence that provides global, multiply redundant, real-time coverage of all GPS satellites, all the time. It routinely and automatically produces the most accurate real-time estimates of GPS satellite orbits and clocks, media calibrations and many other products and performance metrics. The system leverages NASA investments in the global GPS network and the U.S. Government's investment in the Wide Area Augmentation System navigation technology developed at JPL.
• NASA's Earth Science Technology Office funds the development of the Global Differential GPS system, with support from the Solid Earth and Natural Hazards Program within NASA's Earth Science Enterprise, Washington, D.C. More information about the Internet-based Global Differential GPS system is available online at

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Gonna fly now

• It's a technique Orville and Wilbur (God, I still love those names) Wright used a century ago to keep their early airplane afloat. Now the U.S. Air Force thinks it might have legs --- or wings --- again. It's called wing warping. Instead of movable flaps and ailerons to steer and control a plane, warping bends the entire wing to achieve the desired effect. The Air Force has fancied it up a bit and redubbed it "active aeroelastic wing" technology. But the goal of its $41 million investment is, like the Brothers Wright, to produce lighter, more maneuverable planes. >> Related sitesFrom a press release by the NASA Dryden Flight Research Center:

• Engineers and technicians at NASA's Dryden Flight Research Center are wrapping up the last major ground tests this month before beginning the first research flights in a project to demonstrate that twisting or warping flexible wings can enhance aircraft performance.

• The ground vibration and structural mode interaction tests on the Active Aeroelastic Wing (AAW) F/A-18A test aircraft began in late August, and should be completed in mid-September, according to Dryden's AAW project manager Denis Bessette. Following final pre-flight checks, control room training of project staff and updating of mission rules and flight plans, the modified jet fighter could fly in mid-October.

• A joint program of the U.S. Air Force Research Laboratory (AFRL), Boeing's Phantom Works and NASA Dryden, Active Aeroelastic Wing is researching the use of lighter-weight flexible wings for improved maneuverability of future high-performance military aircraft. The program intends to demonstrate improved aircraft roll control through aerodynamically induced wing twist on a full-scale manned supersonic aircraft.

• "The project reflects both a return to aviation's beginnings, when the Wright Brothers devised a primitive wing-warping method to control the Wright Flyer, and a gateway to the future--a future where aircraft will sense their environment, morph, and adapt their shape to the existing flight conditions," said Bessette. "These future aircraft will take advantage of years of evolutionary lessons exhibited in bird-like flight."

• AAW research could also enable thinner, higher aspect-ratio wings on future aircraft, which could result in reduced aerodynamic drag, allowing greater range or payload and improved fuel efficiency. Data obtained from flight tests at Dryden will provide benchmark design criteria as guidance for future aircraft designs.

• "Active Aeroelastic Wing technology is important to the Air Force because it represents a new approach to designing wings, and is applicable to a wide variety of future air vehicle concepts that are under study," said Pete Flick, AAW program manager for the AFRL Air Vehicles Directorate. "The AAW design approach removes some constraints that limit conventional wing design, opening up the envelope for future designers."

• During the current tests, the F-18 rests on three large airbags, while electro-mechanical shakers induce vibrations into the wings at varying amplitudes and frequencies. Test instrumentation measures how the structure reacts as these vibrations propagate through the aircraft to determine potentially adverse effects.

• In the ground vibration tests, the F-18's hydraulics were powered up, but the control surfaces were inactive. The structural mode interaction tests take the process one step further, with the flight controls operating and the interaction of the flight control surfaces with the aircraft structure observed. This test assures that vibrations caused by the actions of the flight controls are damped or suppressed, rather than reinforcing each other to cause large, uncontrolled vibrations or "flutter" that could lead to catastrophic failure of the aircraft structure.

• "The ground vibration and structural mode interaction tests are designed to input vibrations into the aircraft and determine if these vibrations are damped (suppressed) in the expected manner," said Bessette. "The data is used to confirm flutter models and the interaction of the flight control system with the structural elasticity of the aircraft."

• The testbed F/A-18A, provided by the U.S. Navy, has been modified with additional actuators, a split leading edge flap actuation system and thinner wing skins that will allow the outer wing panels to twist up to five degrees. The traditional wing control surfaces?trailing edge ailerons and the leading and trailing edge flaps?are used to provide the aerodynamic force needed to twist or "warp" the wing. Project engineers hope to obtain almost equivalent roll performance of production F/A-18s at transonic and supersonic speeds without using the horizontal stabilators and with smaller control surface deflections.

• A six-month long structural loads testing program on the F/A-18's modified wings?one of the most extensive tests ever performed in Dryden's Flight Loads Laboratory?was conducted in 2001. As part of those tests, the wings were subjected to loads up to 70 percent of the design limit load of the airplane, with load distribution over the wings a particularly critical item.

• The two-phase AAW flight tests will begin with a series of about 30 to 40 parameter identification flights. Boeing's Phantom Works will use data obtained from the first series of flights to refine wing effectiveness models and design the AAW flight control laws. The second phase of research flights to demonstrate the AAW concept with effective control laws should begin in mid- to late 2003, almost 100 years after the Wright Brothers' first powered flight on December 17, 1903.

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Come fly with me

• Boeing has joined a small group of technology bigwigs trying to test a theory that would let engineers negate some of the effects of gravity.
• The American aerospace giant is using the work of controversial Russian scientist Yevgeny Podkletnov, who claims to have developed a device that can shield objects from the Earth's pull.
• Other researchers claim Podkletnov's work is hokum, but considering the cost savings such a device would represent for air travel, Boeing seems intent on getting to the bottom of it all.
• The Russian says he found that objects above a superconducting ceramic disc rotating over powerful electromagnets lost weight, the BBC reports.

• "The reduction in gravity was small, about 2 percent, but the implications --- for example, in terms of cutting the energy needed for a plane to fly --- were immense."

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AUTOMATION AND SOCIETY

• Automation has made a major contribution toward increases in both free time and real wages enjoyed by most workers in industrialized nations.
• Automation has greatly increased production and lowered costs, thereby making automobiles, refrigerators, televisions, telephones, and other goods available to more people.
• It has allowed production and wages to increase, and at the same time the work week has decreased in most Western countries from 60 to 40 hours.

Employment

• Not all the results of automation have been positive, however.
• Some commentators argue that automation has caused overproduction and waste, that it has created alienation among workers, and that it generates unemployment.
• Of these issues, the relationship between automation and unemployment has received the most attention.
• Employers and some economists argue that automation has little if any effect on unemployment—that workers are displaced rather than dismissed and are usually employed in another position within the same company or in the same position at another company that has not automated.
• On the other hand, some labor leaders and economists argue that automation causes unemployment and, if left unchecked, will breed a vast army of unemployed that could disrupt the entire economy.
• They contend that growth in government-generated jobs and in service industries has absorbed those who became unemployed due to automation, and that as soon as these areas become saturated or the programs reduced, the true relationship between automation and unemployment will become known.

Automation and the Individual

• The effect of automation on the individual has been more drastic.
• The worker is either displaced or unemployed.
• Workers who remain must operate or maintain technologically advanced machines, and they may also be required to monitor more of the plant operation and to make on-the-spot decisions.
• Thus, the education and experience levels of these workers are considerably above those of the workers who were displaced.
• The number of workers in more automated industries, especially those using continuous flow processes, tends to be small, and the capital investment in equipment per worker is high.
• The most dramatic difference between these industries and those using Detroit automation is the reduction in the number of semiskilled workers.

• It would appear then that automation has little use for unskilled or semiskilled workers, their skills being the most easily replaced by automated devices. The labor force needed in an automated plant consists primarily of such skilled workers as maintenance engineers, electricians, and toolmakers, all of whom are necessary to keep the automated machinery in good operating order.

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AUTOMATION IN INDUSTRY

• Many industries are highly automated or use automation technology in some part of their operation.
• In communications and especially in the telephone industry, dialing, transmission, and billing are all done automatically.
• Railroads too are controlled by automatic signaling devices, which have sensors that detect cars passing a particular point.
• In this way the movement and location of trains can be monitored.
• The concept of automation is evolving rapidly, partly because the applications of automation techniques vary both within a plant or industry and also between industries.
• The oil and chemical industries, for example, have developed the continuous-flow method of production, owing to the nature of the raw materials used. In a refinery, crude oil enters at one point and flows continuously through pipes in cracking, distillation, and reaction devices as it is being processed into such products as gasoline and fuel oil.
• An array of automatic-control devices governed by microprocessors and coordinated by a central computer is used to control valves, heaters, and other equipment, thereby regulating both the flow and reaction rates.
• In the steel, beverage, and canned food industries, on the other hand, some of the products are produced in batches.
• For example, a steel furnace is charged (loaded with the ingredients), brought up to heat, and a batch of steel ingots produced.
• In this phase very little automation is evident. These ingots, however, may then be processed automatically into sheet or structural shapes by being squeezed through a series of rollers until the desired shape is achieved. See Iron and Steel Manufacture.
• The automobile and other consumer product industries use the mass production techniques of step-by-step manufacture and assembly.

• This technique approximates the continuous-flow concept but involves transfer machines; thus, from the point of view of the auto industry, transfer machines are essential to the definition of automation. See Automobile Industry.

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COMPUTER USE Of Automation

• The advent of the computer has greatly facilitated the use of feedback loops in manufacturing processes.

• Computers and feedback loops have promoted the development of numerically controlled machines (the motions of which are controlled by punched paper or magnetic tapes) and machining centers (machine tools that can perform several different machining operations).

• More recently, the introduction of microprocessors and computer combinations have made possible the development of computer-aided design and computer-aided manufacture (CAD and CAM) technology.

• When using these systems a designer draws a part and indicates its dimensions with the aid of a special light pen on a televisionlike cathode-ray tube computer display screen.

• After the sketch has been completed to the satisfaction of the designer, the computer automatically generates a magnetic or punched tape that directs a machining center in machining the part. See Cathode.Ray Tube; Drafting; Microprocessor.

• Automation has also had an influence on areas of the economy other than manufacturing.

• Small computers are used in systems called word processors, which are rapidly becoming a standard part of the modern office.

• This technology combines a small computer with a cathode-ray display screen, a typewriter keyboard, and a printer.

• It is used to edit texts, to type form letters tailored to the recipient, and to manipulate mailing lists and other data. The system is capable of performing many other tasks that increase office productivity

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FEEDBACK Of Automation

• Essential to all automatic-control mechanisms is the feedback principle, which enables a designer to endow a machine with the capacity for self-correction.
• A feedback loop is a mechanical, pneumatic, or electronic device that senses or measures a physical quantity such as position, temperature, size, or speed, compares it with a preestablished standard, and takes whatever preprogrammed action is necessary to maintain the measured quantity within the limits of the acceptable standard.
• The feedback principle has been used for centuries. An outstanding early example is the flyball governor, invented in 1788 by the Scottish engineer James Watt to control the speed of the steam engine.
• In this device a pair of weighted balls is suspended from arms attached to a spindle, which is connected by gears to the output shaft of the engine.
• At the top of the spindle the arms are linked by a lever with a valve that regulates the steam input.
• As the engine speeds up beyond the desired rate, causing the spindle to rotate faster, the flyballs are driven upward by centrifugal force.
• The action of the flyballs partly closes the input valve, reducing the amount of steam delivered to the engine.
• The common household thermostat is another example of a feedback device.
• In manufacturing and production, feedback loops require that acceptable limits or tolerances be established for the process to be performed; that these physical characteristics be measured and compared with the set of limits; and, finally, that the feedback system be capable of correcting the process so that the measured items comply with the standard.
• Through feedback devices, machines can start, stop, speed up, slow down, count, inspect, test, compare, and measure.
• These operations are commonly applied to a wide variety of production operations that can include milling, boring, bottling, and refining.

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Automation

• Automation, system of manufacture designed to extend the capacity of machines to perform certain tasks formerly done by humans, and to control sequences of operations without human intervention.
• The term automation has also been used to describe nonmanufacturing systems in which programmed or automatic devices can operate independently or nearly independently of human control.
• In the fields of communications, aviation, and astronautics, for example, such devices as automatic telephone switching equipment, automatic pilots, and automated guidance and control systems are used to perform various operations much faster or better than could be accomplished by humans.

• Automated manufacture arose out of the intimate relationship of such economic forces and technical innovations as the division of labor, power transfer and the mechanization of the factory, and the development of transfer machines and feedback systems as explained below.
• The division of labor (that is, the reduction of a manufacturing or service process into its smallest independent steps) developed in the latter half of the 18th century and was first discussed by the British economist Adam Smith in his book An Inquiry into the Nature and Causes of the Wealth of Nations (1776).
• In manufacturing, the division of labor results in increased production and a reduction in the level of skills required of workers.
• The transfer machine is a device used to move a workpiece from one specialized machine tool (see Machine Tools) to another, in such a manner as to properly position the workpiece for the next machining operation.
• Industrial robots (see Robot), originally designed only to perform simple tasks in environments dangerous to human workers, are now extremely dexterous and are being used to transfer, manipulate, and index (that is, to position) both light and heavy workpieces, thus performing all the functions of a transfer machine.
• In actual practice, a number of separate machines are integrated into what may be thought of as one large machine.
• In the 1920s the auto industry combined these concepts into an integrated system of production.
• The goal of this assembly-line system was to make automobiles available to people who previously could not afford them.
• This method of production was adopted by most automobile manufacturers and rapidly became known as Detroit automation.
• Despite more recent advances, it is this system of production that most people think of as automation.

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Artificial Intelligence

• Artificial Intelligence (AI), a term that in its broadest sense would indicate the ability of an artifact to perform the same kinds of functions that characterize human thought.

• The possibility of developing some such artifact has intrigued human beings since ancient times.

• With the growth of modern science, the search for AI has taken two major directions: psychological and physiological research into the nature of human thought, and the technological development of increasingly sophisticated computing systems.

• In the latter sense, the term AI has been applied to computer systems and programs capable of performing tasks more complex than straightforward programming, although still far from the realm of actual thought.

• The most important fields of research in this area are information processing, pattern recognition, game-playing computers, and applied fields such as medical diagnosis.

• Current research in information processing deals with programs that enable a computer to understand written or spoken information and to produce summaries, answer specific questions, or redistribute information to users interested in specific areas of this information.

• In medicine, programs have been developed that analyze the disease symptoms, medical history, and laboratory test results of a patient, and then suggest a diagnosis to the physician. The diagnostic program is an example of so-called expert systems—programs designed to perform tasks in specialized areas as a human would.

• Expert systems take computers a step beyond straightforward programming, being based on a technique called rule-based inference, in which preestablished rule systems are used to process the data. Despite their sophistication, systems still do not approach the complexity of true intelligent thought.

• Many scientists remain doubtful that true AI can ever be developed. The operation of the human mind is still little understood, and computer design may remain essentially incapable of analogously duplicating those unknown, complex processes. Various routes are being used in the effort to reach the goal of true AI.

• One approach is to apply the concept of parallel processing—interlinked and concurrent computer operations. Another is to create networks of experimental computer chips, called silicon neurons, that mimic data-processing functions of brain cells. Using analog technology, the transistors in these chips emulate nerve-cell membranes in order to operate at the speed of neurons.

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MEASURING ACID OR BASE STRENGTH

• The strength of an acid can be measured by the extent to which an acid transfers a proton to water to produce the hydronium ion, H₃O⁺.
• Conversely, the strength of a base is indicated by the extent to which the base removes a proton from water.
• A convenient acid-base scale is calculated from the amount of H₃O⁺ that is formed in water solutions of acids or of OH^- formed in water solutions of bases.
• The former is known as the pH scale and the latter as the pOH scale (pH). The value for pH is equal to the negative logarithm of the hydronium ion concentration—and for pOH, of the hydroxyl ion concentration—in an aqueous solution:
  
  pH = -log [H₃O⁺]
  
  
  pOH = -log [OH^-]
• Pure water has a pH of 7.0. When an acid is added, the hydronium ion concentration [H₃O⁺] becomes larger than that in pure water, and the pH becomes less than 7.0, depending on the strength of the acid.
• The pOH of pure water is also 7.0, and in the presence of a base, the pOH drops to values lower than 7.0.

• The American chemist Gilbert N. Lewis has offered another theory of acids and bases that has the further advantage of not requiring the acid to contain hydrogen. This theory states that acids are electron-pair acceptors and bases are electron-pair donors.
  
• This theory also has the advantages that it works when solvents other than water are involved and it does not require the formation of a salt or of acid-base conjugate pairs. Thus, ammonia is viewed as a base because it can donate an electron pair to the acid boron trifluoride, for example

H₃N: + BF₃=H₃N-BF₃

to form an acid-base association pair.

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BRØNSTED-LOWRY THEORY

• A more satisfactory theory was proposed in 1923 by the Danish chemist Johannes Brønsted and independently by Thomas Lowry, a British chemist.
• Their theory states that an acid is a proton (hydrogen ion, H⁺) donor and a base a proton acceptor.
• Although the acid must still contain hydrogen, the Brønsted-Lowry theory does not require an aqueous medium.
• For example, liquid ammonia, which acts as a base in aqueous solution, can act as an acid in the absence of water by transferring a proton to a base and forming the amide anion (negative ion) NH₂^-:
  
  
  NH₃ + base=H₂^- + base + H⁺

• The Brønsted-Lowry definition of acids and bases also explains why a strong acid displaces a weak acid from its compounds (and likewise for strong and weak bases).

• Here acid-base reactions are viewed as a competition for protons. In terms of a general chemical equation, the reaction of Acid (1) with Base (2)
  
  
  Acid (1) + Base (2)=cid (2) + Base (1)
  
  results in the transfer of a proton from Acid (1) to Base (2).

• In losing the proton, Acid (1) becomes its conjugate base, Base (1). In gaining a proton, Base (2) becomes its conjugate acid, Acid (2).

• The equilibrium represented by the equation above may be displaced either to the left or to the right, and the actual reaction will take place in the direction that produces the weaker acid-base pair. For example, hydrogen chloride (HCl) is a strong acid in water because it readily transfers a proton to water to form a hydronium ion:
  
  
  HCl + H₂O=₃O⁺ + Cl^-
  
  The equilibrium lies mostly to the right because the conjugate base of HCl, Cl^-, is a weak base, and H₃O⁺, the conjugate acid of H₂O, is a weak acid.

• In contrast, hydrogen fluoride, HF, is a weak acid in water because it does not readily transfer a proton to water:
  
  
  HF + H₂O⇄H₃O⁺ + F^-
  
  This equilibrium lies mostly to the left because H₂O is a weaker base than F^-, and because HF is a weaker acid (in water) than H₃O⁺.

• The Brønsted-Lowry theory also explains why water can be amphoteric, that is, why it can serve as either an acid or a base.

• Water serves as a base in the presence of an acid that is stronger than water (such as HCl), in other words, an acid that has a greater tendency to dissociate than does water:

HCl + H₂O⇄H₃O⁺ + Cl^-
Water can also serve as an acid in the presence of a base that is stronger than water (such as ammonia):

NH₃ + H₂O⇄NH₄⁺ + OH^-

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Acids and Bases

Acids and Bases

• Acids and Bases, two classes of chemical compounds that display generally opposite characteristics.
• Acids taste sour, turn litmus (a pink dye derived from lichens) red, and often react with some metals to produce hydrogen gas.
• Bases taste bitter, turn litmus blue, and feel slippery.
• When aqueous (water) solutions of an acid and a base are combined, a neutralization reaction occurs.
• This reaction is characteristically very rapid and generally produces water and a salt.
• For example, sulfuric acid and sodium hydroxide, NaOH, yield water and sodium sulfate:
  
  H₂SO₄ + 2NaOH=H₂O + Na₂SO₄

o Modern understanding of acids and bases began with the discovery in 1834 by the English physicist Michael Faraday that acids, bases, and salts are electrolytes.

o That is, when they are dissolved in water, they produce a solution that contains charged particles, or ions, and can conduct an electric current Ionization. In 1884 the Swedish chemist Svante Arrhenius (and later Wilhelm Ostwald, a German chemist) proposed that an acid be defined as a hydrogen-containing compound that, when dissolved in water, produces a concentration of hydrogen ions, or protons, greater than that of pure water.

o Similarly, Arrhenius proposed that a base be defined as a substance that, when dissolved in water, produces an excess of hydroxyl ions, OH^-. The neutralization reaction then becomes:

H⁺ + OH^-=H₂O

• A number of criticisms of the Arrhenius-Ostwald theory have been made.
• First, acids are restricted to hydrogen-containing species and bases to hydroxyl-containing species.
• Second, the theory applies to aqueous solutions exclusively, whereas many acid-base reactions are known to take place in the absence of water.

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BIRDS IN MOTION

Flying

• Like airplanes, birds rely on lift—an upward force that counters gravity—in order to fly. Birds generate lift by pushing down on the air with their wings.
• This action causes the air, in return, to push the wings up. The shape of wings, which have an upper surface that is slightly convex and a lower surface that is concave, contributes to this effect. To turn, birds often tilt so that one wing is higher than the other.
• Bird tails are also important to flight. Birds tip their tail feathers in different directions to achieve stability and to help change direction while flying. When soaring, birds spread their tail feathers to obtain more lift.
• When landing, birds turn their tails downward, so that their tails act like brakes.

Walking, Running, and Climbing

• Most birds can move their legs alternately to walk and run, and some birds are adept at climbing trees.
• Birds’ agility on land varies widely among different species. The American robin both hops and walks, while the starling usually walks.
• The ostrich can run as fast as 64 km/h (40 mph). Swifts, however, can neither hop nor run; their weak feet are useful only for clinging to vertical surfaces, such as the walls of caves and houses.
• Birds that walk in shallow water, such as herons and stilts, have long legs that facilitate wading.
• Jacanas, which walk on lily pads and mud, have long toes and nails that disperse their weight to help prevent them from sinking.
• Penguins have stubby legs placed far back from their center of gravity. For this reason, they can walk only with an upright posture and a short-stepping gait.

Swimming

• Many birds are excellent swimmers and divers, including such distantly related types of birds as grebes, loons, ducks, auks, cormorants, penguins, and diving petrels.
• Most of these birds have webbed or lobed toes that act as paddles, which they use to propel themselves underwater.
• 
• Others, including auks and penguins, use their wings to propel themselves through the water. Swimming birds have broad, raftlike bodies that provide stability.
• They have dense feather coverings that hold pockets of air for warmth, but they can compress the air out of these pockets to reduce buoyancy when diving.
• Many fish-catching birds can dive to great depths, either from the air or from the water’s surface.
• The emperor penguin can plunge to depths of more than 250 m (850 ft) and remain submerged for about 12 minutes.
• Some ducks, swans, and geese perform an action called dabbling, in which they tip their tails up and reach down with their beaks to forage on the mud beneath shallow water.

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Bird

Bird

• Bird, animal with feathers and wings.
• Birds are the only animals with feathers, although some other animals, such as insects and bats, also have wings.
• Nearly all birds can fly, and even flightless birds, such as ostriches and penguins, evolved from flying ancestors.
• Birds are members of a group of animals called vertebrates, which possess a spinal column or backbone. Other vertebrates are fish, amphibians, reptiles, and mammals.
• 
• Many characteristics and behaviors of birds are distinct from all other animals, but there are some similarities.
• Like mammals, birds have four-chambered hearts and are warm-blooded—having a relatively constant body temperature that enables them to live in a wide variety of environments. Like reptiles, birds develop from embryos in eggs outside of the mother’s body.
• Birds are found worldwide in many habitats. They can fly over some of the highest mountains on earth as well as both of the earth’s poles, dive through water to depths of more than 250 m (850 ft), and occupy habitats with the most extreme climates on the planet, including arctic tundra and the Sahara Desert.
  
  
  
• Birds vary in size from the tiny bee hummingbird, which measures about 57 mm (about 2.25 in) from beak tip to tail tip and weighs 1.6 g (0.06 oz), to the ostrich, which stands 2.7 m (9 ft) tall and weighs up to 156 kg (345 lb). The heaviest flying bird is the great bustard, which can weigh up to 18 kg (40 lb).

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