Local heating effect in point-contact spectroscopy for magnetic metals of Ni and α-Mn

The current-voltage characteristics at a homojunction point-contact of ferromagnetic Ni single crystal and antiferromagnetic -phase Mn polycrystalline metal have been measured at 4.2 K. Several singularities in the first and second derivative of I–V curves are observed at specific bias voltages for both metals. Taking into account the observed temperature dependence of the bulk electrical resistivity and thermal conductivity (and thus mean free path of electrons), we have performed computer simulations of these nonlinear I–V characteristics based on a modified local heating model and compared with the results by a traditional spherical spreading-out (SSO) model. When a constant additive correction to the bulk resistivity near a contact interface is incorporated, our calculated curves are in good agreement with the experimental results.     

A novel PWM strategy to minimize the surge voltage forcurrent-source converters

This paper presents a novel technique of pulsewidth modulation (PWM) wave control to minimize the surge voltage at the turn-off of switching devices. Two kinds of sawtooth carriers with different hypotenuses are employed to obtain a PWM waveform with minimum surge voltage, where each sawtooth carrier appears alternately at every 60° interval relative to the sinusoidal wave cycle. It is difficult to analyze the output waveforms because they are complicated. In order to obtain the analytical result, a frequency analysis approach using a switching function is proposed the results of which are verified experimentally     

Enzymatic synthesis of myristoyl disaccharides and their surface activity

The condensation of trehalose, maltose, cellobiose, sucrose, turanose, palatinose, lactose and melibiose with myristic acid by a lipase (triacylglycerol acylhydrolase; EC 3.1.1.3) from Candida antarctica was examined at 60 °C in a mixture of pyridine and 2‐methyl‐2‐propanol (20/80 by vol.). The reactivity of trehalose was the highest among the tested disaccharides, and maltose and palatinose followed. Cellobiose and lactose were poor substrates for condensation. Condensation of all the disaccharides except for cellobiose and lactose with myristic acid was carried out at various initial disaccharide concentrations to estimate the initial reaction rate. Plots of the initial rates for monomyristoyl disaccharide formation versus the initial disaccharide concentration normalized by the solubility of the disaccharide in the mixture indicated that palatinose was the best substrate, and that trehalose, turanose and maltose were the next best ones. The surface activity of the monoacyl disaccharides scarcely depended on the type of disaccharide. Copyright © 2007 Society of Chemical Industry     

透射式CT与自射线式CT检测核废物桶蒙特卡罗模拟

用蒙特止罗方法对透射式CT（TCT）和自射线式CT（ECT）检测核废物进行模拟实验,用TCT的模拟结果对ECT的模拟结果进行材料吸收系数校正,可以较为准确地确定核废物桶中放射性活度的绝对分布,并可确定放射性核素的种类。     

Three-dimensional finite element analysis for prevailing torque of bolt-nut connection having slight pitch difference

Journal of Mechanical Science and Technology - In a vast industrial field, the bolt-nut connection is widely used and unitized as an important machine component. In order to improve safety and for...     

Coupling of the expressed cannabinoid CB1 and CB2 receptors to phospholipase C and G protein-coupled inwardly rectifying K+ channels.

Signaling of the cannabinoid CB1 and CB2 receptors through phospholipase C (PLC) and G protein-coupled inwardly rectifying K+ channels (GIRK) was studied after their expression in COS7 cells and Xenopus oocytes. The CB1 or CB2 receptor was co-expressed with alpha subunits of the Galphaq family (Galphaq, Galpha11, Galpha14, Galpha15 and Galpha16) in COS7 cells. Receptor-dependent activation of PLC was observed after co-expressing the CB1 receptor with Galpha14, Galpha15 or Galpha16 but not with Galphaq or Galpha11. Co-expression of Gbeta1 and Ggamma2 abolished the activation, indicating that the activation was mediated by Galpha. PLC activation was not observed when the CB2 receptor was expressed alone or co-expressed with any of the above Galpha subunits. Coupling to GIRK was observed with both CB1 and CB2 receptors after expression in Xenopus oocytes. Significantly larger currents were induced when the receptor was co-expressed with both GIRK1 and GIRK4 than with either GIRK alone. Co-expression of Galpha transducin with the receptor significantly reduced the K+ currents, indicating that GIRK activation was mediated by Gbetagamma but not by Galpha. These findings suggest two new signaling pathways for the cannabinoid receptors.     

Modeling and Identification of an Open-frame Underwater Vehicle: The Yaw Motion Dynamics

A semi-autonomous unmanned underwater vehicle (UUV), named LAURS, is being developed at the Laboratory of Sensors and Actuators at the University of Sao Paulo. The vehicle has been designed to provide inspection and intervention capabilities in specific missions of deep water oil fields. In this work, a method of modeling and identification of yaw motion dynamic system model of an open-frame underwater vehicle is presented. Using an on-board low cost magnetic compass sensor the method is based on the utilization of an uncoupled 1-DOF (degree of freedom) dynamic system equation and the application of the integral method which is the classical least squares algorithm applied to the integral form of the dynamic system equations. Experimental trials with the actual vehicle have been performed in a test tank and diving pool. During these experiments, thrusters responsible for yaw motion are driven by sinusoidal voltage signal profiles. An assessment of the feasibility of the method reveals that estimated dynamic system models are more reliable when considering slow and small sinusoidal voltage signal profiles, i.e. with larger periods and with relatively small amplitude and offset.     

Efficient structure synthesis of reactive distillation processes using the IDEAS approach

A new synthesis method for reactive distillation processes is proposed. At each stage of a column, vapor–liquid equilibrium (VLE) is assumed and kinetically controlled reaction in liquid phase is considered. First, the liquid composition space is divided into small subspaces. Then, for each subspace a representative liquid composition is decided and assigned to a module corresponding to a stage of a distillation column. Then, after the calculation of the VLE and the reaction rate, the distribution network (superstructure) connecting all modules by vapor and liquid flow paths is constructed. The feature of the proposed model is that all constraints are linear to the optimization variables: the liquid and vapor flow rate and the liquid hold-up. The developed method was applied to the metathesis reaction of 2-pentene, and a completely new process structure was obtained. The effectiveness of the implied structure was confirmed through a comparison with conventional structures.     

Distributed Telerobotics System Based on Common Object Request Broker Architecture

This paper proposes using CORBA as communication architecture to integrate network-distributed software and robotic systems in support systems for the aged or disabled. The proposed method keeps system costs low and expands availability. Its high scaling and inter-operating ability allows clients and server objects that are written in different languages, run in different operating systems, and connected to different networks to inter-operate. It also enables the system to be extended and integrated with other technologies and applications distributed over the Internet. Based on CORBA, we developed hardware base including a robot arm and an omnidirectional mobile robot and application servers including a task-level robot arm control server, live feedback image server, mobile robot control server and iGPS server. By remotely controlling mobile robot to cooperate with the robot arm, the caregivers or family member can use the developed system for some basic services to the aged or disabled.