Skewing Factor Research Articles

Magnet Skew Technology Investigation for the Reduction of PMLSM Thrust Ripple

Thrust characteristics of permanent magnet linear synchronous motor (PMLSM) are analyzed. It shows that frequency spectrums of thrust ripple, which are mainly caused by end-effect, are quite similar for linear motors with different pole/slot combinations. To apply magnet skew technology, a method using piecewise magnet for skewing factor computation is introduced. According to this piecewise method, a policy for analyzing 3D skew effect model using 2D FEM algorithm is investigated. The application on a 14-pole/12-slot PMLSM validated the algorithm.

Estimating Bayes factors via thermodynamic integration and population MCMC

A Bayesian approach to model comparison based on the integrated or marginal likelihood is considered, and applications to linear regression models and nonlinear ordinary differential equation (ODE) models are used as the setting in which to elucidate and further develop existing statistical methodology. The focus is on two methods of marginal likelihood estimation. First, a statistical failure of the widely employed Posterior Harmonic Mean estimator is highlighted. It is demonstrated that there is a systematic bias capable of significantly skewing Bayes factor estimates, which has not previously been highlighted in the literature. Second, a detailed study of the recently proposed Thermodynamic Integral estimator is presented, which characterises the error associated with its discrete form. An experimental study using analytically tractable linear regression models highlights substantial differences with recently published results regarding optimal discretisation. Finally, with the insights gained, it is demonstrated how Population MCMC and thermodynamic integration methods may be elegantly combined to estimate Bayes factors accurately enough to discriminate between nonlinear models based on systems of ODEs, which has important application in describing the behaviour of complex processes arising in a wide variety of research areas, such as Systems Biology, Computational Ecology and Chemical Engineering.

Generalised parton distributions at HERA and prospects for COMPASS

We present a model of generalised parton distributions based on a forward ansatz in the DGLAP region. We discuss some aspects of the parametrisations, as the dependence in t, with factorised and non-factorised approaches, where t is the square of the four-momentum exchanged at the hadron vertex. The predictions of this model are then compared with DVCS cross sections from H1 and ZEUS, and a related observable, the skewing factor, defined as the following ratio imaginary amplitudes: R≡ImA(γ∗+p→γ+p)|t=0/ImA(γ∗+p→γ∗+p)|t=0. It is an interesting quantity including both the non-forward kinematics and the non-diagonal effects. Finally, we discuss the beam charge asymmetry, which is certainly the most sensitive observable to the different hypothesis needed in the GPDs parametrisations. We show that the approximations done for the t dependence lead to significant differences for the predictions in the HERMES kinematic domain and prospects are given for COMPASS.

Deeply virtual compton scattering in color dipole formalism

In this contribution we summarize recent investigations on the deeply virtual Compton Scattering (DVCS) within the color dipole approach. The color dipole cross section is implemented through the phenomenological saturation model. The role played by its QCD evolution and skewedness effects in the DVCS cross section are discussed. The results are compared with the recent H1 and ZEUS Collaborations data. The skewing factor, defined as the ratio of the imaginary parts of the amplitudes ImA(g*p ® g* p)/ImA(g*p ® gp) can be extracted from the data using recent DVCS and the inclusive inelastic cross section measurements at DESY-HERA. We report on this experimental extraction and compare the results to the theoretical predictions for NLO QCD and the color dipole approach.

An extraction of the skewing factor from DESY-HERA data

In this contribution we present recent investigation on the extraction of the skewing factor, defined as the ratio of the imaginary parts of the amplitudes Im ${\cal A}$(gamma* p <FONT FACE=Symbol>® g</FONT>* p)/ Im ${\cal A}$(gamma* p <FONT FACE=Symbol>® g</FONT> p). This factor is extracted from the data using the recent DVCS and the inclusive inelastic cross section measurements at DESY-HERA. We compare the results to the theoretical predictions for NLO QCD and the color dipole approach.

Dual-Sampling Skewed CMOS Design for Soft-Error Tolerance

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Presented is a circuit technique that mitigates the impact of single-event transient (SET) in deep submicrometer circuits with minimal speed, power, and area penalty. The technique combines a novel dual-sampling flip-flop (DSFF) and the skewed CMOS (SCMOS) circuit style. The DSFF and SCMOS are designed to eliminate SETs with the polarity of $1\rightarrow 0$ and $0\rightarrow 1$, respectively. We study inverter chain circuits as well as sum-of-products implementation of random logic circuits in a typical 0.18-$\mu{\hbox {m}}$ process under the influence of radiation induced soft errors. We quantify the SET tolerance of the proposed technique by using an error map and a recently developed tool soft-error rate analyzer (SERA). The results show that the DSFF incurs no speed penalty, if no SETs have reached the input of DSFF. Otherwise, the DSFF alone eliminates the $1\rightarrow 0$ SETs while incurring a worst case speed and power penalty of 310 ps and 39 $\mu \hbox {W} $, respectively. The SCMOS eliminates the $0\rightarrow 1$ SETs when the skewing factor is greater than four. Thus, the proposed technique potentially eliminates the impact of SETs with both polarities. </para>

Load-skewing task assignment to minimize communication conflicts on network of workstations

Communication latency is an important factor in deciding the performance of a parallel or distributed algorithm, especially in a low speed network environment. In a bus-based network of workstations, a perfectly load balancing arrangement does not always lead to the best performance due to potential communication resource conflicts. Such a situation arises when workstations tend to compete for the shared bus after they all finish their assigned workload at about the same time under such a load arrangement. In this paper, we provide a thorough analysis on how such communication conflicts can be minimized in a bus-based system by using a load-skewing assignment method. A probablistic model is used to analyze the needed skewing factor for cases in which computation requirement is either a deterministic or nondeterministic quantity. Our analytical results are closely confirmed by various simulation and experimental outcomes.

Statistical Applications of the Multivariate Skew Normal Distribution

Summary Azzalini and Dalla Valle have recently discussed the multivariate skew normal distribution which extends the class of normal distributions by the addition of a shape parameter. The first part of the present paper examines further probabilistic properties of the distribution, with special emphasis on aspects of statistical relevance. Inferential and other statistical issues are discussed in the following part, with applications to some multivariate statistics problems, illustrated by numerical examples. Finally, a further extension is described which introduces a skewing factor of an elliptical density.

Human Dendritic Cells Require Exogenous Interleukin-12–Inducing Factors to Direct the Development of Naive T-Helper Cells Toward the Th1 Phenotype

AbstractDendritic cells (DC) are important initiators of specific primary immune responses because they are the only APC that can efficiently activate naive Th cells. DC have the capacity to produce interleukin-12 (IL-12), a cytokine that plays a pivotal role in the development of Th1-mediated cellular immune responses. The present study focuses on the conditions under which human DC produce bioactive IL-12 p70 and, consequently, direct the development of naive T helper (Th) cells toward the Th1 phenotype. Bacteria or bacterial compounds such as Staphylococcus aureus Cowan strain I (SAC) or lipopolysaccharide (LPS) induced substantial IL-12 levels in DC, which could be further upregulated by interferon-γ (IFN-γ), whereas induction of IL-12 production via CD40 ligation required IFN-γ as an obligatory, complementary signal. Also, activated naive Th cells were poor inducers of IL-12 production, unless exogenous IFN-γ was present, whereas activated memory Th cells were effective inducers of IL-12 production and did not require exogenous IFN-γ. Next, the cytokine profiles of matured Th cells that were primed by DC under different conditions were examined. DC promoted the development of naive Th cells into memory Th0 cells that produced both the type 1 cytokine IFN-γ and the type 2 cytokine IL-4. In contrast, after activation with SAC, DC efficiently directed the development of Th1 cells through the release of IL-12. An APC-independent Th cell maturation model, using either recombinant IL-12 or supernatants of SAC-activated DC and neutralizing anti-IL-12 antibodies, confirmed that DC-derived IL-12 was the major Th1 skewing factor. Together, these data indicate that the contact between DC and naive Th cells during the initiation of specific immune responses does not result in the efficient induction of IL-12 production and that, consequently, exogenous IL-12–inducing factors are required to promote primary Th1-mediated cellular immune responses.

The coupling of the coulter counter to a pulse height analyzer for a rapid monitor of size distributions of cells and organelles

The Coulter Counter can be coupled to a pulse height analyzer in order to measure gross volume distributions of biological organisms and organelles. A technique using an integrated distribution permits rapid kinetics of water flow or swelling and shrinking of organelles (within 5–10 sec) to be determined. It has been found that most distributions measured fit the lognormal distribution (which has a skewing factor) with the exception of a poorly-synchronized Chlorella population in which two separate distributions can be observed.

Ein Beitrag zur Berechnung von Asynchronmotoren mit nichtisoliertem Läuferkäfig

At non-insulated squirrel-cage rotors stray-currents may be caused through the fundamental wave and the harmonics of the rotor current within the rotor core. It is theoretically proved, that the influence of the stray-currents and their reaction on the air-gap leakage and the primary circuit can be taken into account by using a complex skewing factor χ v * in the known equations of a squirrel-cage motor for the fundamental wave as well as for the harmonics instead of the normal skewing factor χ v . This statement is not only valid for three-phase but also for two-and single-phase motors.