Determination of Turboprop Reduction Gearbox System Fatigue Life and Reliability

Two computational models to determine the fatigue life and reliability of a commercial turboprop gearbox are compared with each other and with field data. These models are (1) Monte Carlo simulation of randomly selected lives of individual bearings and gears comprising the system and (2) two-parameter Weibull distribution function for bearings and gears comprising the system using strict-series system reliability to combine the calculated individual component lives in the gearbox. The Monte Carlo simulation included the virtual testing of 744,450 gearboxes. Two sets of field data were obtained from 64 gearboxes that were first-run to removal for cause, were refurbished and placed back in service, and then were second-run until removal for cause. A series of equations were empirically developed from the Monte Carlo simulation to determine the statistical variation in predicted life and Weibull slope as a function of the number of gearboxes failed. The resultant L(sub 10) life from the field data was 5,627 hr. From strict-series system reliability, the predicted L(sub 10) life was 774 hr. From the Monte Carlo simulation, the median value for the L(sub 10) gearbox lives equaled 757 hr. Half of the gearbox L(sub 10) lives will be less than this value and the other half more. The resultant L(sub 10) life of the second-run (refurbished) gearboxes was 1,334 hr. The apparent load-life exponent p for the roller bearings is 5.2. Were the bearing lives to be recalculated with a load-life exponent p equal to 5.2, the predicted L(sub 10) life of the gearbox would be equal to the actual life obtained in the field. The component failure distribution of the gearbox from the Monte Carlo simulation was nearly identical to that using the strict-series system reliability analysis, proving the compatibility of these methods

WTC2005-63187 DETERMINATION OF TURBOPROP REDUCTION GEARBOX SYSTEM FATIGUE-LIFE AND RELIABILITY FROM COMPUTER GENERATED TESTS

ABSTRACT Two computational models for the fatigue life and reliability of a turboprop gearbox are compared with each other and with field data. The two models are (1) Monte Carlo simulation of randomly selected lives of individual bearings and gears comprising a gearbox and (2) life analysis of the bearings and gears in the gearbox using the two-parameter Weibull distribution and the Lundberg-Palmgren life theory. These results were compared with field life results from 75 gearbox These life models are based on a modified Lundberg-Palmgren theory due to the similarity in fatigue failures between bearings and gears

Evaluation of scheduling and allocation algorithms while mapping assembly code onto FPGAs

ABSTRACT Migration of software from older general purpose embedded processors onto newer mixed hardware/software Systems-On-Chip (SOC) platforms is becoming an increasingly important topic. Automatic translation of general purpose software binaries and assembly code onto hardware implementations using FPGAs require sophisticated scheduling and allocation algorithms to maximize the resource utilization of such hardware devices. This paper describes the effects of scheduling and chaining of node operations in a CDFG onto an FPGA. The effects of register allocation on scheduled nodes are also discussed. The Texas Instruments C6000 DSP processor architecture was chosen as the DSP processor platform and assembly code, and the Xilinx Virtex II XC2V250 was chosen as the target FPGA. Results are reported on ten benchmarks, which show that scheduling with chaining operations produces the best results on FPGAs, while the addition of register allocation in fact generates poorer designs in terms of area and frequency

A glance into the uterus during in vitro simulation of embryo transfer

The two ®rst authors contributed equally to this work. BACKGROUND: The currently low implantation rate after embryo transfer (ET) is partially attributed to technical aspects, such as catheter type, catheter load, placement of catheter tip and physician skills. METHODS: Mock ET simulations were conducted with a transparent laboratory model of the uterine cavity. The catheter was loaded with alternating air and coloured liquid media. The transfer procedure was recorded by a digital video camcorder for later analysis. Different sequences of air and liquid volumes, as well as liquids of different viscosity were simulated. RESULTS: Injection of liquid with air into the uterus formed an air bubble which blocked the transport of the transferred liquid towards the fundus. The distribution of the transferred matter within the uterine cavity was determined by the composition of the liquid±air sequence and the viscosity ratio between the transferred liquid and the uterine¯uid. CONCLUSIONS: It is suggested that the catheter load should contain minimal volumes of air in order to enhance the embryos' chances of reaching the site of implantation. The viscosity of the transferred liquid should be as close as possible to that of the uterine¯uid in order to avoid transport of embryos towards the cervix

Influencia de las pautas de crianza sobre los comportamientos de socialización en los jóvenes

El presente trabajo enmarcado en el enfoque hermenéutico y argumentado desde la teoría general de los sistemas, relaciona la influencia que ejercen las pautas de crianza generadas desde la familia y reforzadas en la escuela, sobre los comportamientos de socialización en los jóvenes del Colegio Salesiano Juan del Rizzo. De igual manera establece la incidencia de las pautas de crianza en la generación de posibles comportamientos violentos. Se identifica que los aspectos más representativos que inciden en el deterioro de las relaciones familiares son: la debilidad en los procesos de comunicación intra-familiar, la falta de interés tanto de los padres como maestros, y la incidencia de los factores socio-medio-ambientales. Por otra parte, diversos aspectos del desarrollo del niño tales como el crecimiento físico, los cambios psicológicos y emocionales, la adaptación social, son entre otros, argumentos válidos que facilitan la socialización en los individuos, que de llegar a ser bien orientados, redundan en beneficio de una sana personalidad. A partir del análisis de los resultados se puede concluir que las experiencias y convivencias realizadas por los jóvenes, son un reflejo de las pautas de crianza utilizadas en cada familia y a su vez son el resultado de la socialización adaptada por el individuo, demostrando que los padres excesivamente estrictos o permisivos limitan las posibilidades de crecimiento de los infantes y la generación de conflictos.El presente trabajo enmarcado en el enfoque hermenéutico y argumentado desde la teoría general de los sistemas, relaciona la influencia que ejercen las pautas de crianza generadas desde la familia y reforzadas en la escuela, sobre los comportamientos de socialización en los jóvenes del Colegio Salesiano Juan del Rizzo. De igual manera establece la incidencia de las pautas de crianza en la generación de posibles comportamientos violentos. Se identifica que los aspectos más representativos que inciden en el deterioro de las relaciones familiares son: la debilidad en los procesos de comunicación intra-familiar, la falta de interés tanto de los padres como maestros, y la incidencia de los factores socio-medio-ambientales. Por otra parte, diversos aspectos del desarrollo del niño tales como el crecimiento físico, los cambios psicológicos y emocionales, la adaptación social, son entre otros, argumentos válidos que facilitan la socialización en los individuos, que de llegar a ser bien orientados, redundan en beneficio de una sana personalidad. A partir del análisis de los resultados se puede concluir que las experiencias y convivencias realizadas por los jóvenes, son un reflejo de las pautas de crianza utilizadas en cada familia y a su vez son el resultado de la socialización adaptada por el individuo, demostrando que los padres excesivamente estrictos o permisivos limitan las posibilidades de crecimiento de los infantes y la generación de conflictos

Tweaking the spin-wave dispersion and suppressing the incommensurate phase in LiNiPO4 by iron substitution

Elastic and inelastic neutron scattering studies of Li(Ni$_{1-x}$Fe$_{x}$)PO$_4$ single crystals reveal anomalous spin-wave dispersions along the crystallographic direction parallel to the characteristic wave vector of the magnetic incommensurate phase. The anomalous spin-wave dispersion ({\it magnetic soft mode}) indicates the instability of the Ising-like ground state that eventually evolves into the incommensurate phase as the temperature is raised. The pure LiNiPO$_4$ system ($x=0$), undergoes a first-order magnetic phase transition from a long-range incommensurate phase to an antiferromagnetic ground state at {\it T}$_N$ = 20.8 K. At 20% Fe concentrations, although the AFM ground state is to a large extent preserved as that of the pure system, the phase transition is second-order, and the incommensurate phase is completely suppressed. Analysis of the dispersion curves using a Heisenberg spin Hamiltonian that includes inter- and in-plane nearest and next-nearest neighbor couplings reveals frustration due to strong competing interactions between nearest- and a next-nearest neighbor site, consistent with the observed incommensurate structure. The Fe substitution only slightly lowers the extent of the frustration, sufficient to suppress the IC phase. An energy gap in the dispersion curves gradually decreases with the increase of Fe content from $\sim$2 meV for the pure system ($x=0$) to $\sim$0.9 meV for $x=0.2$

T cell antigen discovery via signaling and antigen-presenting bifunctional receptors

CD8^+ T cells recognize and eliminate tumors in an antigen-specific manner. Despite progress in characterizing the antitumor T cell repertoire and function, the identification of target antigens remains a challenge. Here we describe the use of chimeric receptors called signaling and antigen-presenting bifunctional receptors (SABRs) in a cell-based platform for T cell receptor (TCR) antigen discovery. SABRs present an extracellular complex comprising a peptide and major histocompatibility complex (MHC), and induce intracellular signaling via a TCR-like signal after binding with a cognate TCR. We devised a strategy for antigen discovery using SABR libraries to screen thousands of antigenic epitopes. We validated this platform by identifying the targets recognized by public TCRs of known specificities. Moreover, we extended this approach for personalized neoantigen discovery

T cell antigen discovery via trogocytosis

T cell receptor (TCR) ligand discovery is essential for understanding and manipulating immune responses to tumors. We developed a cell-based selection platform for TCR ligand discovery that exploits a membrane transfer phenomenon called trogocytosis. We discovered that T cell membrane proteins are transferred specifically to target cells that present cognate peptide–major histocompatibility complex (MHC) molecules. Co-incubation of T cells expressing an orphan TCR with target cells collectively presenting a library of peptide–MHCs led to specific labeling of cognate target cells, enabling isolation of these target cells and sequencing of the cognate TCR ligand. We validated this method for two clinically employed TCRs and further used the platform to identify the cognate neoepitope for a subject-derived neoantigen-specific TCR. Thus, target cell trogocytosis is a robust tool for TCR ligand discovery that will be useful for studying basic tumor immunology and identifying new targets for immunotherapy

Induction of CD4 T cell memory by local cellular collectivity

he balance between effector and central memory T cells shifts toward the latter as the number of T cells participating in immune responses increases. Polonsky et al. determined the mechanisms by which T cell quorum sensing affects memory differentiation by using live-cell imaging to track cell proliferation and differentiation. They found that the rate of memory CD4+ T cell differentiation is determined by cell number. This rate substantially increases above a threshold number of locally interacting cells. Mathematical modeling suggests that the number of initially seeded cells and the number of cell divisions are not critical. Instead, the instantaneous number of interacting cells continuously modulates the differentiation rate. This is partly fueled by increased sensitivity to the cytokines interleukin-2 (IL-2) and IL-6, independent of any effects on cell proliferation