The Modeling and Analysis of the Current Density in Current Gauges and Contact System

Transmission lines and contact assemblies adapted for conducting considerable values of constant andmomentary current ratings are usually built as the set of many isolated parallel paths, in addition spacesbetween electric contacts are little compared with their width. Ensuring the big power-driven load capacityto a maximum is aimed at it. In these types of paths flow of the electricity through each of them is,how it could be expected, uneven. It is an effect of the occurrence of skin effect and an effect of closeracquaintance. So, we cannot increase their power-driven load capacity proportionally to the amount oftransmission lines. Inductances are different, depending on the place of the path. The following calculationsare supposed to explain and to depict, which from paths (in case of contact assemblies – electriccontacts) will be mostly exposed at the flow of the electricity, as well as will let the resistance understandthe relation of the contact effect of the material and the structure of joints

Welding when contacts close electrical circuits

The paper presents analysis of the welding due to pre-arcing contacts and due to bounce arcs. Welding happens following arcing at make or break where the arc roots generate over 10 times more heat than seen in the former constriction example and thus melt and soften the contact material, arc welding. The higher the value of velocity of contact closing, the shorter the arcing time. High velocity has a negative aspect since it causes bouncing of contacts finger from the butt. Welding caused by solidification of a molten metal bridge is an extreme case of resistance welding. The welding force increases during the early operation cycles.Стаття являє собою аналіз умов зварювання контактів. Зварювання відбувається як наслідок виникнення і гасіння дуги, там де тепловиділення на порядок більше, де матеріал розм’якшується, плавиться і має місце зварювання контактів. Чим вище швидкість зближення контактів, тим коротше час дугового впливу. Висока швидкість має негативний вплив, оскільки це викликає відскок контактних пальців від з’єднання. Зварювання, викликане твердінням металу розплавленого містка, є граничним випадком опору зварювання. Сила зварювання збільшується на протязі ранніх циклів комутації.Статья представляет собой анализ условий сваривания. Сваривание происходит следом за возникновением и гашением дуги в основании дуги, где тепловыделение на порядок больше, при этом материал размягчается, плавится, имеет место дуговая сварка. Чем выше скорость сближения контактов, тем короче время дугового воздействия. Высокая скорость имеет негативное влияние, так как это вызывает отскок контактных пальцев из соединения. Сваривание, вызванное затвердеванием металла расплавленного мостика, является предельным случаем сопротивления свариванию. Сила сваривания увеличивается в течение ранних циклов коммутации

The Road from Medical Injury to Claims Resolution: How No-Fault and Tort Differ

In the area of medical malpractice, no-fault has been offered as a response to the criticisms leveled against tort litigation for medical injuries. Five issues of no-fault are examined within the context of obstetrical malpractice

Performance of the HgCdTe detector for MOSFIRE, an imager and multi-object spectrometer for Keck Observatory

MOSFIRE is a new multi-object near-infrared spectrometer for the Keck 1 telescope with a spectral resolving power of R~3500 for a 0.7″ slit (2.9 pixels). The detector is a substrate-removed 2K × 2K HAWAII 2-RG HgCdTe array from Teledyne Imaging Sensors with a cut-off wavelength of 2.5 μm and an operational temperature of 77K. Spectroscopy of faint objects sets the requirement for low dark current and low noise. MOSFIRE is also an infrared camera with a 6.9′ field of view projected onto the detector with 0.18″ pixel sampling. Broad-band imaging drives the requirement for 32-channel readout and MOSFIREs fast camera optics implies the need for a very at detector. In this paper we report the final performance of the detector selected for MOSFIRE. The array is operated using the SIDECAR ASIC chip inside the MOSFIRE dewar and v2.3 of the HxRG software. Dark current plus instrument background is measured at <0.008 ē s^(−1) pixel^−1 on average. Multiple Correlated Double Sampling (MCDS) and Up-The-Ramp (UTR) sampling are both available. A read noise of <5ē rms is achieved with MCDS 16 and the lowest noise of 3ē rms occurs for 64 samples. Charge persistence depends on exposure level and shows a large gradient across this detector. However, the decay time constant is always ~660 seconds. Linearity and stability are also discussed

Applying the Socio-Ecological Model to barriers to implementation of ACL injury prevention programs: A systematic review

Background: Preventing anterior cruciate ligament (ACL) injuries is important to avoid long-term adverse health consequences. Identifying barriers to implementation of these prevention programs is crucial to reducing the incidence of these injuries. Our purpose was to identify barriers of implementation for ACL injury prevention programs and suggest mechanisms for reducing the barriers through application of a SocioEcological Model (SEM). Methods: Studies investigating ACL prevention program effectiveness were searched in Medline via PubMed and the Cochrane Library, and a subsequent review of the references of the identified articles, yielded 15 articles total. Inclusion criteria encompassed prospective controlled trials, published in English, with ACL injuries as the primary outcome. Studies were independently appraised by 2 reviewers for methodological quality using the PEDro scale. Barriers to implementation were identified when reported in at least 2 separate studies. A SEM was used to suggest ways to reduce the identified barriers. Results: Five barriers were identified: motivation, time requirements, skill requirements for program facilitators, compliance, and cost. The SEM suggested ways to minimize the barriers at all levels of the model from the individual through policy levels. Conclusion: Identification of barriers to program implementation and suggesting how to reduce them through the SEM is a critical first step toward enabling ACL prevention programs to be more effective and ultimately reducing the incidence of these injurie

Effects of augmented local abdominal activation patterns on lower extremity biomechanics during landing in males and females

"This research assessed changes in lower extremity biomechanics as a result of augmented local abdominal contractions during double leg landings. The study design followed a two-day (control and intervention days) within subject model in which two conditions on each day were compared, (control-control and control-experimental) with between sex comparisons. Fifty subjects (25 males and 25 females) were activity matched and represented a sample of healthy and recreationally active individuals. A repeated measures ANOVA comparing control and experimental conditions on the intervention day revealed that all subjects significantly increased local abdominal activation during 150ms prior to landing. However, a 2 (sex) x 3 (muscle) x 2 (phase of landing) repeated measures ANOVA demonstrated that only males maintained this contraction during the 150ms time interval after landing. A repeated measures ANOVA evaluating changes in leg spring stiffness (LSS) as a result of the augmented local abdominal contraction showed a sex by condition interaction demonstrating that only males experienced significant increases in LSS from control to experimental condition while females demonstrated no significant changes. No significant differences by condition were noted when assessing changes in ankle, knee, and hip energetics. The evaluation of lower extremity total joint displacements across condition demonstrated that males increased LSS through decreases in hip range of motion while females showed no significant changes in hip range of motion but increased knee and ankle motion. From these results we concluded that augmented local abdominal activation during a double leg landing task increased LSS by decreasing hip range of motion in males. "--Abstract from author supplied metadata

The Exemplar T8 Subdwarf Companion of Wolf 1130

We have discovered a wide separation (188.5") T8 subdwarf companion to the sdM1.5+WD binary Wolf 1130. Companionship of WISE J200520.38+542433.9 is verified through common proper motion over a ~3 year baseline. Wolf 1130 is located 15.83 +/- 0.96 parsecs from the Sun, placing the brown dwarf at a projected separation of ~3000 AU. Near-infrared colors and medium resolution (R~2000-4000) spectroscopy establish the uniqueness of this system as a high-gravity, low-metallicity benchmark. Although there are a number of low-metallicity T dwarfs in the literature, WISE J200520.38+542433.9 has the most extreme inferred metallicity to date with [Fe/H] = -0.64 +/- 0.17 based on Wolf 1130. Model comparisons to this exemplar late-type subdwarf support it having an old age, a low metallicity, and a small radius. However, the spectroscopic peculiarities of WISE J200520.38+542433.9 underscore the importance of developing the low-metallicity parameter space of the most current atmospheric models.Comment: Accepted to ApJ on 05 September 2013; 33 pages in preprint format, 8 figures, 3 table

Strong Nebular Line Ratios in the Spectra of z~2-3 Star-forming Galaxies: First Results from KBSS-MOSFIRE

We present initial results of a deep near-IR spectroscopic survey covering the 15 fields of the Keck Baryonic Structure Survey (KBSS) using MOSFIRE on the Keck 1 telescope, focusing on a sample of 251 galaxies with redshifts 2.0< z < 2.6, star-formation rates 2 < SFR < 200 M_sun/yr, and stellar masses 8.6 < log(M*/M_sun) < 11.4, with high-quality spectra in both H- and K-band atmospheric windows. We show unambiguously that the locus of z~2.3 galaxies in the "BPT" nebular diagnostic diagram exhibits a disjoint, yet similarly tight, relationship between the ratios [NII]6585/Halpha and [OIII]/Hbeta as compared to local galaxies. Using photoionization models, we argue that the offset of the z~2.3 locus relative to z~ 0 is explained by a combination of harder ionizing radiation field, higher ionization parameter, and higher N/O at a given O/H than applies to most local galaxies, and that the position of a galaxy along the z~2.3 star-forming BPT locus is surprisingly insensitive to gas-phase oxygen abundance. The observed nebular emission line ratios are most easily reproduced by models in which the net ionizing radiation field resembles a blackbody with effective temperature T_eff = 50000-60000 K and N/O close to the solar value at all O/H. We critically assess the applicability of commonly-used strong line indices for estimating gas-phase metallicities, and consider the implications of the small intrinsic scatter in the empirical relationship between excitation-sensitive line indices and stellar mass (i.e., the "mass-metallicity" relation), at z~2.3.Comment: 41 pages, 25 figures, accepted for publication in the Astrophysical Journal. Version with full-resolution figures available at http://www.astro.caltech.edu/~ccs/mos_bpt_submit.pd

Kinematic analysis of functional lower extremity perturbations

Background. Sudden changes in direction on a single weight-bearing-limb are commonly associated with injury to the lower extremity. The purposes of this study were to assess the between day reliability of hip, knee, and ankle kinematic displacements achieved with internal and external femur-on-weight-bearing-tibia rotation perturbations and to determine the effect of these perturbations on three dimensional hip, knee and ankle kinematics. Methods. Twenty recreationally active, healthy college students with no history of significant orthopedic injury (10 male, 10 female) were subjected to a forward and either internal or external rotary perturbation of the trunk and thigh on the weight-bearing-tibia while three dimensional kinematics were simultaneously collected. The protocol was repeated 24–48 h later to assess reliability. Findings. External perturbations resulted in significant internal rotation (IR) of the tibia on the femur (mean 7.3 (SD 3.9°)) and IR of the femur on the pelvis (mean 6.8 (SD 5.4°)) (P &lt; 0.05). Internal perturbations resulted in significant external rotation (ER) of the tibia on the femur (mean 6.8 (5.9°)) and ER of the femur on the pelvis (mean 10.7 (SD 96.1°)) (P &lt; 0.05). Additionally the external perturbation results in a significantly greater knee valgus (mean 3.6 (SD 2.2°)) position while the internal perturbation results in a significantly greater knee varus position (mean 2.3 (SD 3.5°)) (P &lt; 0.05). External perturbation hip and knee total joint displace-ments revealed moderate to strong reliability (Intraclass Correlation Coefficient2,k = 0.67–0.94) while internal perturbations revealed slightly higher Intraclass Correlation Coefficients2,k(0.80–0.96). Interpretation. The lower extremity perturbation device provides a consistent external and internal perturbation of the femur on the weight-bearing-tibia. The observed transverse and frontal plane kinematics are similar to motions observed during cross-over and side-stepping tasks