Magnetic bearings: Fifty years of progress

Magnetic bearings are just beginning to be flown in spacecraft systems, but their development spans more than 50 years. The promise of completely noncontacting, unlubricated rotating systems operating at speeds substantially beyond the range of conventional bearings, and with no wear and virtually no vibration, has provided the incentive to develop magnetic bearing technology for many diverse applications. Earnshaw theorized in 1842 that stable magnetic suspension is not possible in all three spatial directions unless the magnetic field is actively controlled. Since that time, researchers have attempted to successfully support spinning rotors in a stable manner. Development of magnetic suspension systems over the past fifty years has included progress on both passive (permanent magnet) and active (electromagnet) systems. The improvements in bearing load capacity, stiffness, and damping characteristics are traced. The trends in rotor size, rotational kinetic energy, and improvements in active control systems capabilities are also reviewed. Implications of superconductivity on suspension system design and performance are discussed

Simulation for Product Driven Systems

Due to globalisation, companies have to become more and more agile in order to face demand fluctuations and growing customisation needs. Indeed, the mass production market moves to a mass customization one, which could be defined as the production of a wide variety of end products at a low unit cost. During last years, many efforts have been done in order to improve operating system reactivity (with the Flexible Manufacturing initiative for example), but the manufacturing decision process did not really change, and then doesn't enable to fully make the most of these new operating system skills. Facing these new trends, a lot of new research works are focusing on identification technologies, like Auto-ID, biometry or vision ones. Radio Frequency Identification technology (RFID) represents a quick and safe way to track products, opening the way of linking informational and physical flows, and providing an accurate, real time vision of the shop floor. These new technologies appear like a catalyst to change the fifty years old way of controlling production through traditional MRP² systems

High-Density Use of Septic Systems, Avon Lake, Iowa

Avon Lake, a rural-residential subdivision located southeast of Des Moines, has mostly summer cabins around a remnant gravel quarry. Surface material in the area is sand. Each of the homes has a shallow sand-point well for a water supply and a septic system for sewage treatment. Septic systems were examined for evidence of failure, house-to-house surveys were performed, and well water samples were taken. Fifty percent of the septic systems have been operating satisfactorily for more than 20 years. Only one of 68 well water samples contained fecal coliform bacteria. Thirty-six samples exceeded the nitrate standard, the highest being 25.6mg/1 N. Nitrate concentration seemed to change in space but not with well age. Nitrogen loadings from cropland, septic systems, and animals were also estimated; they ranged from 40-120 lb/acre (45-135 kg/ha) for cropland, 35 lb/acre (39 kg/ha) for septic systems, and 13 lb/acre (15 kg/ha) for dogs. All three of these could be important sources of nitrogen to the groundwater

An economic comparison of three heavy lift airborne systems

Current state of art trends indicate that a 50-ton payload helicopter could be built by the end of the decade. However, alternative aircraft that employ LTA principles are shown to be more economically attractive, both in terms of investment and operating costs for the ultra-heavy lift role. Costing methodology follows rationale developed by airframe manufacturers, and includes learning curve factors

Charting a New Course to Retirement: How Charter Schools Handle Teacher Pensions

In this "Ed Short" from the Thomas B. Fordham Institute, Amanda Olberg and Michael Podgursky examine how public charter schools handle pensions for their teachers. Some states give these schools the freedom to opt out of the traditional teacher-pension system; when given that option, how many charter schools take it? Olberg and Podgursky examine data from six charter-heavy states and find that charter participation rates in traditional pension systems vary greatly -- from over 90 percent in California to less than one out of every four charters in Florida. As for what happens when schools choose not to participate in state pension plans, the authors find that they most often provide their teachers with defined-contribution plans (401(k) or 403(b)) with employer matches similar to those for private-sector professionals. But some opt-out charters offer no alternative retirement plans for their teachers (18 percent in Florida, 24 percent in Arizona)

California: Round 1 - State-Level Field Network Study of the Implementation of the Affordable Care Act

This report is part of a series of 21 state and regional studies examining the rollout of the ACA. The national network -- with 36 states and 61 researchers -- is led by the Rockefeller Institute of Government, the public policy research arm of the State University of New York, the Brookings Institution, and the Fels Institute of Government at the University of Pennsylvania.In September 2010, six months after the passage of the Affordable Care Act, California became the first state in the nation to create its own insurance exchange, eventually named Covered California. This accelerated timeline was consistent with California's desire to be, in the words of the state's Health and Human Services Secretary and Exchange Board Chair Diana Dooley, the "lead car" in implementation of federal health care reform. Because of the speed with which it approached this task, as well as the sheer size of its coverage expansion, the decisions California has made have been influential both regionally and nationally. What has transpired in the state has had implications for other states as they addressed difficult issues, including minimizing adverse selection, promoting cost-conscious consumer choice, and seamlessly coordinating with public programs