Estimation of the Reliability of the Gear–Motor System Using a Markov Model

Journal of Machinery Manufacture and Reliability - In this article, the reliability of a gear–motor system is analyzed on the condition that the failure of the gear leads under certain...     

Interactive monitoring portal for fusion simulations

The Center for Simulation of RF Wave Interactions with Magnetohydrodynamics (SWIM) Project is a proto-Fusion Simulation Program (FSP) whose goal is to study high-performance fusion plasmas and perform comprehensive simulations that are essential to the development of fusion. SWIM team members are geographically distributed and utilize distributed supercomputers for computational simulations. Due to the highly distributed computational work environment, the SWIM team has the difficulty of monitoring code runs and discovering historical runs. To alleviate this difficulty a web-based monitoring portal has been developed and deployed.The monitoring portal tracks the progress of simulations and automatically collects metadata in real-time. This capability helps scientists to effectively utilize precious computer resources. Furthermore, the portal provides a web-based interface for post-run analysis, such as visualizing the results, logging the user comments, and rating the simulation quality. The user interface provides rapid discovery capability via multi-field searching and sorting.The development of the monitoring portal used open source software, such as Python, Django, MySQL, and Apache. It uses MDSplus for data management, Memcached for data caches, and OpenID for single sign-on security.This paper describes the software architecture, related technologies and deployment experiences of the monitoring portal.     

Operation Request Gatekeeper: a software system for remote access control of diagnostic instruments in fusion experiments

Tokamak diagnostic settings are repeatedly modified to meet the changing needs of each experiment. Enabling the remote diagnostic control has significant challenges due to security and efficiency requirements. The Operation Request Gatekeeper (ORG) is a software system that addresses the challenges of remotely but securely submitting modification requests. The ORG provides a framework for screening all the requests before they enter the secure machine zone and are executed by performing user authentication and authorization, grammar validation, and validity checks. A prototype ORG was developed for the ITER CODAC that satisfies their initial requirements for remote request submission and has been tested with remote control of the KSTAR Plasma Control System. This paper describes the software design principles and implementation of ORG as well as worldwide test results.     

校园局域网防御ARP攻击解决方案

目前,移动存储设备以及校园网的广泛使用,使得在校园网内产生了ARP攻击,造成了网络的严重瘫痪。本文通过对ARP攻击原理的分析,定位ARP攻击源头,提出校园局域网内有效的防御方法及解决方案。     

C语言与汇编语言相互调用实现混合编程

讲解了C语言与汇编语言相互调用的基本技术,二者结合实现混合编程的方法和在相互调用过程中需注意的一些问题,并给出了应用实例。两者相互调用有效结合,扬长避短,是一种行之有效的程序设计及开发方法。     

Stability analysis of the FitzHugh-Nagumo differential equations driven by impulses: applied to the electrical firing of magnocellular neurons

A stability analysis is carried out for a mathematical model which describes the electrical firing of a single vasopressin neuron. The model used in a FitzHugh-Nagumo-type system which is driven by impulses. The analysis is based on recent developments in the stability theory of impulsive differential equations. Conditions are derived under which the system of differential equations is stable at two of its equilibrium points. Biologically this bistability represents the cell alternating between periods of electrical activity and silence. The conditions for stability are specified in terms of the amplitude and frequency of the impulses perturbing the system. Both stochastic and deterministic impulses are considered.     

New Dyes and Intermediates for Synthetic-polymer Fibres. 7,7-Dioxo-Benzo(K, /)thioxan-thene-3,4-dicarboxylic Acid Imides

The synthesis of benzo [k, l] thioxanthene-3,4-dicarbo-xylic acid-7,7-dioxide is described. Condensation of this heterocycle with amines, or oxidation of the corresponding imides of benzo [k, l] thioxanthene-3,4-dicarboxylic acid, affords a new range of dyes which colour synthetic-polymer fibres, especially polyester, in yellow shades of excellent fastness to light and sublimation.     

A new remote control room for tokamak operations

This paper presents a summary of a new remote tokamak control room constructed near the offices of DIII-D's scientific staff. This integrated system combines hardware, software, data, and control of the room (R-232) into a unified package that has been designed and constructed in a generic fashion so that it can be used with any tokamak operating worldwide. The room is approximately 300 ft² and can accommodate up to 12 seated participants. Mounted on the wall facing each scientist are five 52″ LCD televisions and mounted to the wall on their right are six 24″ LCD monitors. Each seat has associated with it a 24″ monitor, network connection, and power and the scientist is either provided with a computer or they can use their own. The room has been used for operation of DIII-D, EAST, and KSTAR. Due to the long distances, data from EAST and KSTAR was brought back to local DIII-D computers in one large parallel network transfer and subsequently served to scientists in the remote control room to other US collaborators. This parallel data transfer allowed the data to be available to US participants between pulses making remote experimental participation highly effective.     

Thermal behaviour of 6H-SiC bipolar transistors: spice simulation and applications

As material quality improves and growth technology develops, SiC BJTs are regaining interest. They have the advantage of carrier modulation, high current capabilities and lower initial voltage drop. In this work, the thermal behaviour of 6H-SiC bipolar transistors is simulated. The examined figures of merit such as input resistance h₁₁, current gain β and transconductance g_m show superior performance of 6H-SiC BJTs, at high temperatures, when compared to similar silicon counterparts. In the range of temperatures −20 to 160 °C, drawbacks found in Si BJTs are attenuated or eliminated with the use of SiC BJTs. These advantages are transferred to 6H-SiC based circuits. The built current mirror shows quasi-ideal behaviour while the designed input stage of the amplifier has a voltage gain thermally stabilised up to 140 °C.     

Smoke formation from burning polystyrene and its suppression

Studies have been made of the influence on smoke generation from polystyrene of the incorporation of a number of apparently inert solids, the smoke-producing tendency being expressed in terms of the maximum specific optical density of smoke per unit weight of polymer consumed. Of the compounds investigated, by far the most efficient smoke suppressant is pyrogenic silica, the effect of which is, over a wide range, directly proportional to the total surface area of the material introduced. Examination of partially burned polystyrene-pyrogenic silica composites reveals the presence at the surface of a hard rigid skin, which is not observer with polystyrene alone of with polymer samples containing other additives. The formation of a protective skin is also indicated by the kinetics of forced burning of these composites where the weight loss is a linear function of log time and by measurements of the rate of change of thickness of polymer samples during combustion. Thermogravimetric experiments in which polystyrene and pyrogenic silica are heated in contact with one another show that the silica encourages the formation of a carbon residue from the polymer. A mechanism of skin production is proposed which involves the build-up of layers of tangential spherical silica particles cemented together by cross-linked polystyrene.