基于ABR业务的计算机数据信元丢失分析

ＡＴＭ论坛定义了可用比特率（ＡＢＲ）业务作为充分利用ＡＴＭ网络带宽的手段。该类业务主要面向对时延和时延变化率不敏感的数据业务提供支持，所以应保证极低的信元丢失率。为了做到这一点，关键是合理地设计流量控制机制和ＡＴＭ交换机缓存的大小。由于目前的数据业务大多数由计算机产生并具有开／关特征，所以我们对具有开／关特征的ＡＢＲ业务源进行了分析，推导出在多开／关业务源混合作用下ＡＴＭ交换机的极限信元丢失率的计算公式，分析了缓存长度动态变化对ＡＢＲ业务的影响，并针对一个１２端口的ＡＴＭＬＡＮ交换机进行了仿真分析。对于设计具有开／关ＡＢＲ业务的ＡＴＭ交换机的缓存大小，所得出的结论具有指导意义。

Research of Marine Sensor Web Based on SOA and EDA

A great deal of ocean sensor observation data exists, for a wide range of marine disciplines, derived from in situ and remote observing platforms, in real-time, near-real-time and delayed mode. Ocean monitoring is routinely completed using sensors and instruments. Standardization is the key requirement for exchanging information about ocean sensors and sensor data and for comparing and combining information from different sensor networks. One or more sensors are often physically integrated into a single ocean ‘instrument' device, which often brings in many challenges related to diverse sensor data formats, parameters units, different spatiotemporal resolution, application domains, data quality and sensors protocols. To face these challenges requires the standardization efforts aiming at facilitating the so-called Sensor Web, which making it easy to provide public access to sensor data and metadata information. In this paper, a Marine Sensor Web, based on SOA and EDA and integrating the MBARI's PUCK protocol, IEEE 1451 and OGC SWE 2.0, is illustrated with a five-layer architecture. The Web Service layer and Event Process layer are illustrated in detail with an actual example. The demo study has demonstrated that a standard-based system can be built to access sensors and marine instruments distributed globally using common Web browsers for monitoring the environment and oceanic conditions besides marine sensor data on the Web, this framework of Marine Sensor Web can also play an important role in many other domains' information integration.

Design and Realization of Metadata Standard for Informationized Construction of the Auxiliary Shaft in Longgu Mine

Based on the analysis of status quo of metadata technology and the informationized freezing construction of an auxiliary shaft in Longgu mine, the necessity and feasibility of applying metadata standards for informationized construction is discussed. The prototype of metadata standard for the construction is designed and established by using a modeling method, and the framework with XML/RDF for such standard is given.

A Metadata Model Based on Coupling Testing Information to Increase Testability of Component

A software component must be tested every time it is reused in order to assure quality of component itself and system in which it is to be integrated.So how to increase testability of component has become a key technology in the software engineering community.Here a method is introduced to increase component testability.And meanings of component testability and relative effective ways to increase testability are summarized.Then definitions of component coupling testing criterion,DU-I(Definition-Use Information) and OP-Vs(Observation-Point Values)are given.Base on these,a definition-use table is introduced,which includes DU-A and OP-Vs item,to help component testers to understand and observe interior details about component under test better.Then a framework of testable component based on above DU-table is given.These facilities provide ways to detect errors,observe state variables by observation-points based monitor mechanism.Moreover,above methods are applied to our application developed by ourselves before,and some test cases are generated.Then our method is compared with Orso method and Kan method using the same example,presenting the comparison results.The results illustrate the validity of our method,effectively generating test cases and killing more mutants.

Design of Central Management & Control Unit for Onboard High-Speed Data Handling System

The Main Optical Telescope (MOT) is an important payload of the Space Solar Telescope (SST) with various instruments and observation modes. Its real-time data handling and management and control tasks are arduous. Based on the advanced techniques of foreign countries, an improved structure of onboard data handling systems feasible for SST, is proposed. This article concentrated on the development of a Central Management & Control Unit (MCU) based on FPGA and DSP. Through reconfigurating the FPGA and DSP programs, the prototype could perform different tasks. Thus the inheritability of the whole system is improved. The completed dual-channel prototype proves that the system meets all requirements of the MOT. Its high reliability and safety features also meet the requirements under harsh conditions such as mine detection.

Remote I/O Unit for Optical Fiber Demmunication

Abstract:Based on optical fiber technology, the main electric circuit of the remote I/O unit controller is studied. And the application of the system is illustrated.

Efficient controller area network data compression for automobile apphcations

Controller area networks （CANs） have been designed for multiplexing communication between electronic control units （ECUs） in vehicles and many high-level industrial control applications. When a CAN bus is overloaded by a large number of ECUs connected to it, both the waiting time and the error probability of the data transmission are increased. Thus, it is desirable to reduce the CAN frame length, since the duration of data transmission is proportional to the frame length. In this paper, we present a CAN message compression method to reduce the CAN frame length. Experimental results indicate that CAN transmission data can be compressed by up to 81.06% with the proposed method. By using an embedded test board, we show that 64-bit engine management system （EMS） CAN data compression can be performed within 0.16 ms; consequently, the proposed algorithm can be successfully used in automobile applications.

A new method of rapid quality detection of vacuum insulation panels

A new method of measuring gas pressure in vacuum insulation panels(VIPs)is reported in this study,which provides a fast and efficient quality control option of production.Although there are different methods of measuring gas pressure for VIPs,connecting an internal measurement gauge to external data acquisition units is problematic.The thin high barrier film covering the panel’s core usually prevents external electrical wires or mechanical devices being connected to the inside of the VIPs.To solve this problem,a micro capacitive pressure sensor with 0 to 250 Pa detection range is developed to detect the vacuum pressure.The sensor has high linearity and a sensitivity of 10 mV/Pa.Moreover,through the communication mode study,an ultrasound communications system for VIPs is designed.It shows from operation that this system is stable and reliable,and quick for communication speed.This new method enables the quality detection of VIPs to be completed within 1 second.The minimum detectable pressure of VIPs is below 1 Pa,and the measurement error can be controlled around 5%.