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We give an overview of wind and ocean power generation methods. Wind generation is now an established large global business while ocean generation is still in the prototype stage of development. The most important parameter for commercial acceptance of these technologies is the levelized cost of electricity produced by them. We discuss areas necessary for further cost improvement of wind generation. We further discuss the types of electrical generators used in these applications. [ABSTRACT FROM PUBLISHER]

I examine present and future applications of superconductors. The host of requirements that must be satisfied for a successful commercial application are described and discussed briefly. The substantial role of materials in applications, the large number of requirements on successful commercial superconducting wire, and the trends in superconducting material development are discussed. [ABSTRACT FROM AUTHOR]

General Electric, under contract with the Air Force Research Labs (AFRL), has successfully developed and tested a high speed, multimegawatt superconducting generator. The generator was built to demonstrate high temperature superconducting (HTS) generator technology for application in a high power density Multimegawatt Electric Power System (MEPS) for the Air Force. The demonstration tested the generator under load conditions up to 1.3 MW at over 10,000 rpm. The new MEPS generator achieved 97% efficiency including cryocooler losses. All test results indicate that the generator has a significant margin over the test points and that its performance is consistent with program specifications. This demonstration is the first successful full-load test of a superconducting generator for the Air Force. In this paper we describe the development of the generator and present some key test results used to validate the design. Extrapolation to a higher power density generator is also discussed. [ABSTRACT FROM AUTHOR]

A small high-temperature superconductor (HTS) coil was designed and tested at the General Electric Global Research Center to evaluate the overcurrent capability for the HTS generator rotor. The superconducting rotor coil is a layer-wound racetrack coil using the BSCCO 2223 conductor. Overcurrent simulation tests have been done to simulate the fault operation condition for the generator based on previous analysis work. The obtained data are used to evaluate the performance of the HTS material in generator applications. [ABSTRACT FROM AUTHOR]

When a synchronous generator connected to the power grid experiences a fault, it is required to stay on line, ride through the fault, and be able to carry full rated field current when the fault is cleared. The peak current during these events could be 2 times higher than the normal operating current. This may cause an HTS rotor coil to go into normal state and generate Joule heating. If the fault event is short enough and the heat dumped can be carried away by the cooling system, the coil may recover to the superconducting state at the end of the fault. Otherwise, the coil may thermally run away, or ‘quench’. To investigate the quench behavior of the HTS rotor coil of the 100 MVA generator at GE Global Research Center, a 1.5 MVA prototype coil was developed and tested to quench under different conditions. The experiment design, set up, tests and test results are presented in this paper. [ABSTRACT FROM AUTHOR]

High-temperature superconducting (HTS) coils are generally stable against transient thermal disturbances. Protection against spontaneous quenches is not a main design issue for an HTS coil. However, HTS coils used in many electric devices such as motors, generators, transformers, and current limiters will operate under over-current fault conditions, which may result in a coil quench and thermal runaway. Those electric devices should be able to ride through some grid fault conditions and remain functional. This requires a certain over-current capability of the HTS coils. This paper discusses the over-current requirements from grid faults and the thermal transient responses of a BSCCO coil. It presents the analysis results of the coil subjected to over-current pulses at different operating conditions. The study also investigates the thermal runaway current and its relationship with the over-current pulse. [ABSTRACT FROM AUTHOR]

HTS wires, which may be used in many devices such as magnets and rotating machines, may be subjected to mechanical strains from electromagnetic, thermal and centripetal forces. In some applications these strains will be repeated several thousand times during the lifetime of the device. We have measured critical current degradation due to repeated strain cycles for both compressive and tensile strains. Results for BSCCO-2223 HTS conductor samples are presented for strain values upto 0.5% and cycle numbers up to and beyond 104. [ABSTRACT FROM AUTHOR]

Recent studies have shown that efforts to curb youths' alcohol use, such as increasing the price of alcohol or limiting youths' access, have succeeded but may have had the unintended consequence of increasing marijuana use. This possibility is troubling in light of the doubling of teen marijuana use from 1990 to 1997. What impact will recent increases in cigarette prices have on the demand for other substances, such as marijuana? To better understand how the demand for marijuana and tobacco responds to changes in the policies and prices that affect their use, we explore the National Household Survey on Drug Abuse (NHSDA) from 1990 to 1996. We find evidence that both higher fines for marijuana possession and increased probability of arrest decrease the probability that a young adult will use marijuana. We also find that higher cigarette taxes appear to decrease the intensity of marijuana use and may have a modest negative effect on the probability of use among males. [ABSTRACT FROM AUTHOR]

The prevalence and costs of alcohol and drug disorders pose a serious social concern for policymakers. In this paper, we use data from the National Household Surveys on Drug Abuse (NHSDA) to estimate simple descriptive statistics and analysis of variance (ANOVA) models of the relationship between symptoms of dependence and labor market outcomes for alcohol, cigarettes, marijuana, and other illicit drugs. For men, we find that substance use with symptoms of dependence is associated with both lower employment rates and fewer hours of work. For women, we find that substance use with symptoms of dependence is associated with lower employment rates, but we find no consistent evidence of a relationship between symptoms of dependence and the number of hours worked. Finally, all of our point estimates are smaller in magnitude when we control for multiple substance use, suggesting that comorbidities play a critical role in the relationship between substance use and labor market outcomes. Our results suggest that policymakers and researchers should consider the full spectrum of substance use and dependence rather than focusing on the simple use of a single substance. [ABSTRACT FROM AUTHOR]

The cost and financing of mental health services is gaining increasing importance with the spread of managed care and cost-cutting measures throughout the health care system. The delivery of mental health services through structured employee assistance programs (EAPs) could be undermined by revised health insurance contracts and cutbacks in employer-provided benefits at the workplace. This study uses two recently completed national surveys of EAPs to estimate the costs of providing EAP services during 1993 and 1995. EAP costs are determined by program type, worksite size, industry, and region. In addition, information on program services is reported to determine the most common types and categories of services and whether service delivery changes have occurred between 1993 and 1995. The results of this study will be useful to EAP managers, mental health administrators, and mental health services researchers who are interested in the delivery and costs of EAP services. [ABSTRACT FROM AUTHOR]

A recent study published in the Journal of Health Economics by French and Zarkin [French, M.T., Zarkin, G.A., 1995. Is moderate alcohol use related to wages? Evidence from four worksites, Journal of Health Economics 14, 319-344] found evidence of a positive, inverse-U-shaped relationship between wages and alcohol consumption for individuals at four worksites. In this paper, we attempted to replicate French and Zarkin's findings using a combined sample of prime-age workers from the 1991 and 1992 National Household Surveys on Drug Abuse (NHSDA). Whereas French and Zarkin found that individuals who consume approximately 1.5 to 2.5 drinks per day have higher wages than non-drinkers and heavy drinkers, we found no evidence of a turning point at this consumption level for either men or women. Our results do suggest that men who use alcohol have approximately 7% higher wages than men who do not drink, and this apparent wage premium is approximately the same over a wide range of alcohol consumption. For women, the estimated alcohol use premium is approximately half as large as for men and is statistically insignificant. [ABSTRACT FROM AUTHOR]

To estimate the fraction of United States (U.S.) adults who are eligible for treatment to reduce elevated low-density lipoprotein (LDL) cholesterol levels based on Adult Treatment Panel II (ATP II) guidelines and the percent reduction in LDL cholesterol required by those who qualify for treatment, we analyzed data on 7,423 respondents to Phase 2 of the third National Health and Nutrition Examination Survey (NHANES III) administered between 1991 and 1994. Approximately 28% of the U.S. adult population aged > or = 20 years is eligible for treatment based on ATP II guidelines. Eighty-two percent of adults with coronary heart disease are not at their target LDL cholesterol level of 100 mg/dl. Of those eligible for treatment, 65% report that they receive no treatment. Overall, 40% of people who qualify for drug therapy require an LDL cholesterol reduction of > 30% to meet their ATP II treatment goal. Approximately 75% of those with coronary heart disease who qualify for drug therapy require an LDL cholesterol reduction of >30%. Although elevated LDL cholesterol levels can be treated, prevalence rates in the U.S. adult population remain high. Several recent studies indicate that a considerable percentage of people treated with drug therapy do not reach their treatment goals. The findings in this study provide at least a partial explanation for why many patients receiving therapy do not reach their treatment goals: they require a larger reduction in LDL cholesterol than many therapies can provide. [ABSTRACT FROM AUTHOR]