DYNAMIC ANALYSIS OF THE EFFECT OF CENTRIFUGAL AND CORlOLlS FORCES IN SWINGING A BAT

This paper reports a dynamic analysis by computer simulation of bat swinging, taking into account inertial forces at the wrist joint, and which consist of centrifugal and Coriolis forces generated from a body turn and internal rotation of the upper limbs. The ideal bat swing generated by optimisation using a mathematical model is also described. Based on the dynamic analysis, it is shown that the inertial forces play an important role in the process of flexion and extension between a bat and the upper limbs during a bat swing, and that the effects of gravity on a bat is much smaller than those from inertial forces. It was also proven from the optimisation that an ideal bat swing, a swing using minimal torque at the wrist, exists

Light dark matter in leptophobic Z' models

Recent experimental results in direct dark matter detection may be interpreted in terms of a dark matter particle of mass around 10 GeV/c^2. We show that the required scenario can be realized with a new dark matter particle charged under an extra abelian gauge boson Z' that couples to quarks but not leptons. This is possible provided the Z' gauge boson is very light, around 10-20 GeV/c^2 in mass, and the gauge coupling constant is small, alpha' ~ 10^(-5). Such scenarios are not constrained by accelerator data

VLSI architectures for computing multiplications and inverses in GF(2-m)

Finite field arithmetic logic is central in the implementation of Reed-Solomon coders and in some cryptographic algorithms. There is a need for good multiplication and inversion algorithms that are easily realized on VLSI chips. Massey and Omura recently developed a new multiplication algorithm for Galois fields based on a normal basis representation. A pipeline structure is developed to realize the Massey-Omura multiplier in the finite field GF(2m). With the simple squaring property of the normal-basis representation used together with this multiplier, a pipeline architecture is also developed for computing inverse elements in GF(2m). The designs developed for the Massey-Omura multiplier and the computation of inverse elements are regular, simple, expandable and, therefore, naturally suitable for VLSI implementation

D * polarization vs. R D(∗) anomalies in the leptoquark models

Polarization measurements in B → D(*)Ƭν̅ are useful to check consistency in new physics explanations for the RD and RD* anomalies. In this paper, we investigate the D* and Ƭ polarizations and focus on the new physics contributions to the fraction of a longitudinal D* polarization (F D*/L ), which is recently measured by the Belle collaboration F D*/L = 0:60 ± 0:09, in model-independent manner and in each single leptoquark model (R2, S1 and U1) that can naturally explain the RD(*) anomalies. It is found that B(B+/c → Ƭ⁺ν) severely restricts deviation from the Standard Model (SM) prediction of F D*/L,SM = 0:46 ± 0:04 in the leptoquark models: [0:43; 0:44], [0:42; 0:48], and [0:43; 0:47] are predicted as a range of F D*/L for the R2, S1, and U1 leptoquark models, respectively, where the current data of RD(*) is satised at 1 σ level. It is also shown that the Ƭ polarization observables can much deviate from the SM predictions. The Belle II experiment, therefore, can check such correlations between RD(*) and the polarization observables, and discriminate among the leptoquark models

Magnetic phase diagram of the frustrated S=1/2 chain magnet LiCu_2O_2

We present the results of the magnetization and dielectric constant measurements on untwinned single crystal samples of the frustrated S=1/2 chain cuprate LiCu_2O_2. Novel magnetic phase transitions were observed. A spin flop transition of the spiral spin plane was observed for the field orientations H||a,b. The second magnetic transition was observed at H~15 T for all three principal field directions. This high field magnetic phase is discussed as a collinear spin-modulated phase which is expected for an S=1/2 nearest-neighbor ferromagnetic and next-nearest-neighbor antiferromagnetic chain system

Smart Power Devices and ICs Using GaAs and Wide and Extreme Bandgap Semiconductors

We evaluate and compare the performance and potential of GaAs and of wide and extreme bandgap semiconductors (SiC, GaN, Ga2O3, diamond), relative to silicon, for power electronics applications. We examine their device structures and associated materials/process technologies and selectively review the recent experimental demonstrations of high voltage power devices and IC structures of these semiconductors. We discuss the technical obstacles that still need to be addressed and overcome before large-scale commercialization commences

DYNAMICS ANALYSIS OF PEDALING MOTION IN RACING CYCLE WITH COMPUTER SIMULATION

This paper reports the new method based on the computer simulation for the dynamics analysis of the pedaling motion in a racing cycle. At first, we describe three-dimensional mathematical models of lower limbs and the cycle, and then explain the formulation as the systems of Lagrange equations. Time-series angular displacements of each joint, the crank arm, and each pedal were obtained by capturing actual human pedaling motions. The 'ideal' pedal forces were computed by using the model of the cycle. The method for solving the 'inverse kinematics problem' is also proposed. As the results of the dynamic simulation, we obtained several dynamic properties of the three-dimensional pedaling motion. And the differences between the three-dimensional pedaling motion and the two dimensional motion were also described