Magentically actuated compressor

A vibration free fluid compressor particularly adapted for Stirling cycle cryogenic refrigeration apparatus comprises a pair of identical opposing ferromagnetic pistons located in a housing and between a gas spring including a sealed volume of a working fluid such as gas under pressure. The gas compresses and expands in accordance with movement of the pistons to generate a compression wave which can be vented to other apparatus, for example, a displacer unit in a Stirling cycle engine. The pistons are urged outwardly due to the pressure of the gas; however, a fixed electromagnetic coil assembly located in the housing adjacent the pistons, is periodically energized to produce a magnetic field which interlinks the pistons in such a fashion that the pistons are mutually attracted to one another. The mass of the pistons, in conjunction with the compressed gas between them, form a naturally resonant system which, when the pistons are electromagnetically energized, produces an oscillating compression wave in the entrapped fluid medium

Non-contacting power transfer device

A transformer for coupling AC electrical energy from a stationary element to a rotating element without the use of sliding contacts is described. The transformer is of the rotary type and includes a ferrite core and two primary windings which are stationary with respect to a seconary winding which rotates within an annular cavity adjacent an axial bore in the core. The core is comprised of two cup type core halves. Electrical connection to the secondary winding is made through a split bobbin assembly which couples to a coaxial shaft assembly located in the axial bore. The electrical coupling to the coaxial shaft assembly is made through a continuous transverse channel connecting the axial bore with the annular cavity. The transverse channel forms a single air gap; however, it is not open directly to free space but is shielded by the magnetic permeable material of the core halves

Microstructure of horseshoe nails using neutron diffraction

Neutron diffraction allows non-destructive testing of the bulk microstructure of mechanical components. The microstructures of horseshoe nails made through three different processes have been explored as a function of position along the nail. Despite all nails being made of similar plain low carbon steel and being process annealed after manufacture, the microstructures are far from the same. Nails made from strip, using a cold forging stamping process, show narrower diffraction peaks indicating a narrower distribution of lattice parameters and also show diffraction peak intensity ratios closer to those expected for unstrained steel. Thus the distribution of the orientation of grains in these nails is closer to that of undistorted steel compared to nails made through the other two processes considered – one a drawing from wire, the other a combination of rolling and cold forging. The blades of the drawn nails showed little preferred orientation but the converse was true in the heads. Differing patterns of preferred orientation suggest that the various manufacturing approaches result in substantially different mechanical advantages for the three types of nails, a result in accord with mechanical testing

Exploring the experience of biological children of foster parents : their views on family as adults

Despite the fact that family foster care is a large part of the current child welfare system, little is known about the experience of biological children of foster parents. This qualitative research study analyzed the stories of ten adults who grew up in foster homes as biological children of foster parents from a family systems perspective. Common themes and areas for future research were identified. Participants identified and described diverse experiences in which both positive aspects as well as individual and family struggles . Participants described exposure to foster siblings behaviors and knowledge about their lives. Due to this exposure, participants describe, areas of stress as well as changes in perspective. In many cases this led to an increase in family closeness, feelings of gratitude and the development of positive personal attributes. Participants also identified an awareness of parental stress in the areas of finances, discipline, and relationships with foster children. Effects of foster children entering and exiting the home in regards to adjustment and closeness of relationships were also discussed. Findings indicated a need for further research and attention to the experiences of foster family members

Mechanical capacitor

A new energy storage system (the mechanical capacitor), using a spokeless magnetically levitated composite ring rotor, is described and design formulas for sizing the components are presented. This new system is configured around a permanent magnet (flux biased) suspension which has active servo control in the radial direction and passive control in the axial direction. The storage ring is used as a moving rotor and electronic commutation of the stationary armature coils is proposed. There is no mechanical contact with the rotating spokeless ring; therefore, long life and near zero rundown losses are projected. A 7-kW h system is sized to demonstrate feasibility. A literature review of flywheel energy storage systems is also presented and general formulas are developed for comparing rotor geometries

Gravitational macrosegregation in binary Pb-Sn alloy ingots

A space shuttle experiment employing the General Purpose (Rocket) Furnace (GPF) in its isothermal mode of operation is manifested on MSL-3, circa 1989. The central aim of this experiment is to investigate the effect of reduced gravity levels on the segregation behavior in a slowly, and isothermally, cooled sample of a binary Pb-15 wt% Sn alloy. This experiment should be able to simulate, in a small laboratory sample, some aspects of the segragation phenomena occurring in large industrial ingots. Ground-based experiments conducted in the single-cavity simulator of the GPF, in support of the microgravity experiment are described in detail. The results of the MSFC experiments are compared with other related experiments conducted at Case Western Reserve University (CWRS), wherein the isothermal constraints were relaxed. The isothermally processed samples indicate a small and gradual increase in fraction eutectic, and a corresponding increase in tin content, from the bottom to the top of the ingot. The radial variations are minimal near the ingot bottom, but there are large radial variations in the top half. In the CWRU experiments, more severe segregations, including segregation defects known as freckles. Follow up experiments employing the GPF without the isothermal constraints, or other suitably modified space shuttle hardware are suggested

Exact location of dopants below the Si(001):H surface from scanning tunnelling microscopy and density functional theory

Control of dopants in silicon remains the most important approach to tailoring the properties of electronic materials for integrated circuits, with Group V impurities the most important n-type dopants. At the same time, silicon is finding new applications in coherent quantum devices, thanks to the magnetically quiet environment it provides for the impurity orbitals. The ionization energies and the shape of the dopant orbitals depend on the surfaces and interfaces with which they interact. The location of the dopant and local environment effects will therefore determine the functionality of both future quantum information processors and next-generation semiconductor devices. Here we match observed dopant wavefunctions from low-temperature scanning tunnelling microscopy (STM) to images simulated from first-principles density functional theory (DFT) calculations. By this combination of experiment and theory we precisely determine the substitutional sites of neutral As dopants between 5 and 15A below the Si(001):H surface. In the process we gain a full understanding of the interaction of the donor-electron state with the surface, and hence of the transition between the bulk dopant (with its delocalised hydrogenic orbital) and the previously studied dopants in the surface layer.Comment: 12 pages; accepted for publication in Phys. Rev.

OR14-1PATTERNS AND TRANSITIONS IN SUBSTANCE USE AMONG YOUNG SWISS MEN

Introduction. The stages of involvement in illicit drugs other than cannabis remain vague and few studies focused on the last steps of drug-use trajectories. This study investigated this topic. Methods. We used data from the Swiss Longitudinal Cohort Study on Substance Use Risk Factors (C-SURF) to assess exposure to drug use (alcohol, tobacco, 16 illicit drugs including heroin, and five prescription drugs including opioids) at two times point (N = 5,041). Patterns and trajectories of drug use were studied using latent transition analysis (LTA) and cross-lagged panel models. Results. The LTA identified five classes of drug users showing a pattern involving adding alcohol, tobacco, cannabis, middle-stage drugs (uppers, hallucinogens, inhaled drugs), and final-stage drugs (e.g. heroin, ketamine, crystal meth). The most common transition was to remain in the same latent class. Heroin use predicted later opioid use (b = .071, p = .003) but not the reverse (b = -.005, p = .950). Conclusion. The pattern of drug use displayed the well-known sequence of drug involvement (licit drugs/cannabis/other illicit drugs), but added a distinction between "middle-stage" and "final-stage" drugs. Progression along the whole drug course remained rare among participants in their twenties. For the final stage, heroin appeared as to be a step for opioid us