Linux中NFS实现机制分析

ＮＦＳ是Ｌｉｎｕｘ中实现网络文件共享的关键。本文主要分析了ＮＦＳ的实现机制。包括ＮＦＳ与ＶＦＳ、ＲＰＣ的接口和ＮＦＳ高速缓存,并以系统调用ｓｙｓｒｅａｄ（）为例剖析了ＮＦＳ的工作流程。在本文分析的基础之上,可以对Ｌｉｎｕｘ和ＮＦＳ作出适当的改进,开发出功能强大的分布式文件系统。     

NFS和NIS—Sun操作系统（SunOS）的网络服务

ＳｕｎＯＳ提供了非常丰富的网络服务，本文对Ｓｕｎ工作站的操作系统Ｓｕｎ ＯＳ及其网络服务作了初步介绍，着重介绍了ＮＦＳ的工作机制和管理配置，并概述了为ＮＦＳ提供服务的ＲＰＣ／ＸＤＲ，最后还简述了ＳｕｎＯＳ的另一个重要服务ＮＩＳ的原理和应用。     

NDP C—386在PC环境下DSP TMS320C30系统中的应用

ＰＣ环境下ＤＳＰ ＴＭＳ３２０Ｃ３０系统是一个被广泛采用的高速实时数字信号处理系统。本文介绍一种高性能ＰＣ软件开发环境ＮＤＰＣ－３８６语言编译器，对于数据量处理较大的ＤＳＰ系统，该语言在其中有较好应用。同时，本文指出在ＮＤＰ Ｃ－３８６语言程序时应注意的问题。     

etang游戏动态

３ＤＦＸ今天宣布预发售Ｖｏｏｄｏｏ５ Ｖｏｏｄｏｏ５基于３ＤＦＸ的ＶＳＡ－１００芯片,首次提供了对ＦＳＡＡ的支持（Ｆｕｌｌ－ｓｃｅｎｅａｎｔｉ－ａｌｉａｓｉｎｇ）以及反锯齿效果等…… Ｆｉｎａｌ Ｆａｎｔａｓｙ Ｘ（最终幻想Ｘ）同时登陆ＰＳ２和 ＰＣ 日本史克威尔近日宣布将于今年秋季同时在ＰＳ２和ＰＣ上发布《最终幻想１０》的ＢＥＴＡ测试版。这是最终幻想系列首次同步登陆ＰＣ吧？对于那些没有次世代主机的 ＦＦ ＦＡＮＳ来说,无疑是个好消息。游戏的正式发售时间依然定在２００１年春季,看来还需要等待颇长一段时间…     

MS—DOS6最重要的特色—MULTICONFLG

在ＭＳ－ＤＯＳ６诸多的新功能中，最富特色的莫过于ＭＵＬＴＩＣＯＮＦＩＧ，即它在ＣＯＮ－ＦＩＧ．ＳＹＳ中所具有的多重可选择性。本文通过实例介绍了这一功能的应用。     

分布式计算环境中典型RPC的比较研究

本文介绍了分布式计算环境中两种典型的远程过程调用机制：ＯＳＦ／ＤＣＥ中选用的ＲＰＣ，即ＮＣＳ２．０，和Ｓｕｎ／ＯＮＣ中的ＲＰＣ。文中重点在以下七个方面进行了比较性研究：数据表示，联编，可扩展性与一致性，传输层无关性与透明性，可靠性，安全性和多线程技术。最后，介绍了为实现两种ＲＰＣ间的可移植性和可互操作性所作的努力。     

基于SUPCON JX—300间歇过程监控系统的实现

本文介绍了一个基于ＳＵＰＣＯＮＪＸ－３００的间歇生产过程监控系统的实现，并给出了控制系统结构和基于ＪＸ－３００的ＳＣ语言的具体实施方法，在某调味品公司的酱油生产过程中得到应用，取得了显著的经济效益。     

A FEATURE－BASED PRODUCT MODELLING SYSTEM ON PC （CASE STUDY OF PARTS DESIGN FOR PRESS MACHINE）

ＡＦＥＡＴＵＲＥ－ＢＡＳＥＤＰＲＯＤＵＣＴＭＯＤＥＬＬＩＮＧＳＹＳＴＥＭＯＮＰＣ（ＣＡＳＥＳＴＵＤＹＯＦＰＡＲＴＳＤＥＳＩＧＮＦＯＲＰＲＥＳＳＭＡＣＨＩＮＥ）ＹｏｎａｓＨａｇｏｓ；ＴｏｎｇＢｉｎｇｓｈｕＡｂｓｔｒａｃｔ：Ｔｈｉｓａｒｔｉｃｌｅｒｅｐｏ...     

MAPFTAM—AI的实现及其在UFO中的应用

首先介绍ＭＡＰ制订的ＦＴＡＭ－ＡＩ标准，对它的五类函数的功能和结构进行分析，然后讨论它在ＳＵＮ－ＵＮＩＸ上的实现，提出了一种积木式构造方法，最后介绍在网络环境下，应用ＦＴＡＭ－ＡＩ服务开发的、多台计算机之间的文件操作系统程序ＵＦＯ。     

初级程序员软件考试辅导系列讲座第四讲PC－DOS使用简介

初级程序员软件考试辅导系列讲座第四讲ＰＣ－ＤＯＳ使用简介周必水ＭＳ－ＤＯＳ是美国ＭＩＣＲＯＳＯＦＴ公司开发的磁盘操作系统，在ＩＢＭ公司为ＰＣ选用后，又将其命名为ＰＣ－ＤＯＳ。在ＰＣ机及其兼容机中配置了几个操作系统，ＤＯＳ是其主操作系统，它是一个单用户...     

Voices that cannot be heard: Can shyness explain how we communicate on Facebook versus face-to-face?

Social networking sites have gained popularity among all populations, especially young adults. Personality traits were found to be predictive of how individuals use social media. Therefore, this study sought to examine the association between shyness and self-disclosure to a Facebook friend as well as self-disclosure to a face-to-face friend. Two studies were conducted. The first study tested how shyness and social loneliness are related to self-disclosure to a Facebook friend to whom an individual talks most often. The second, follow-up study tested how shyness is related to self-disclosure to a Facebook friend to whom a person speaks to only though Facebook, and also to a face-to-face friend to whom the participants talk only face-to-face and never through Facebook. Participants were college students from a large research university in the United States. Study 1 found a negative association between shyness and self-disclosure to a Facebook friend. Study 2 found a negative association between shyness and self-disclosure to a face-to-face friend. The theoretical implications and limitations are discussed.     

A hybrid system approach for supporting digital libraries

A digital library (DL) consists of a database which contains library information and a user interface which provides a visual window for users to search relevant information stored in the database. Thus, an abstract structure of a digital library can be defined as a combination of a special purpose database and a user-friendly interface. This paper addresses one of the fundamental aspects of such a combination. This is the formal data structure for linking an object oriented database with hypermedia to support digital libraries. It is important to establish a formal structure for a digital library in order to efficiently maintain different types of library information. This article discusses how to build an object oriented hybrid system to support digital libraries. In particular, we focus on the discussion of a general purpose data model for digital libraries and the design of the corresponding hypermedia interface. The significant features of this research are, first, a formalized data model to define a digital library system structure; second, a practical approach to manage the global schema of a library system; and finally, a design strategy to integrate hypermedia with databases to support a wide range of application areas. Received: 15 December 1997 / Revised: June 1999     

Template-Based Gait Authentication Through Bayesian Thresholding

While gait recognition is the mapping of a gait sequence to an identity known to the system, gait authentication refers to the problem of identifying whether a given gait sequence belongs to the claimed identity. A typical gait authentication system starts with a feature representation such as a gait template, then proceeds to extract its features, and a transformation is ultimately applied to obtain a discriminant feature set. Almost every authentication approach in literature favours the use of Euclidean distance as a threshold to mark the boundary between a legitimate subject and an impostor. This article proposes a method that uses the posterior probability of a Bayes' classifier in place of the Euclidean distance. The proposed framework is applied to template-based gait feature representations and is evaluated using the standard CASIA-B gait database. Our study experimentally demonstrates that the Bayesian posterior probability performs significantly better than the de facto Euclidean distance approach and the cosine distance which is established in research to be the current state of the art.      

Speech and sensor in guiding an electric wheelchair

Many people with disabilities do not have the dexterity necessary to control a joystick on an electric wheelchair. Moreover, they have difficulty to avoid obstacles. The aim of this work is to implement a multi-modal system to control the movement of an Electric wheelchair using small vocabulary word recognition system and a set of sensors to detect and avoid obstacles. The methodology adopted is based on grouping a microcontroller with a speech recognition development kit for isolated word from a dependent speaker and a set of sensors. In order to gain in time design, tests have shown that it would be better to choose a speech recognition kit and to adapt it to the application. The text was submitted by the authors in English.     

Optimized data rate allocation for dynamic sensor fusion over resource constrained communication networks

This article presents a new method to solve a dynamic sensor fusion problem. We consider a large number of remote sensors which measure a common Gauss–Markov process. Each sensor encodes and transmits its measurement to a data fusion center through a resource restricted communication network. The communication cost incurred by a given sensor is quantified as the expected bitrate from the sensor to the fusion center. We propose an approach that attempts to minimize a weighted sum of these communication costs subject to a constraint on the state estimation error at the fusion center. We formulate the problem as a difference-of-convex program and apply the convex-concave procedure (CCP) to obtain a heuristic solution. We consider a 1D heat transfer model and a model for 2D target tracking by a drone swarm for numerical studies. Through these simulations, we observe that our proposed approach has a tendency to assign zero data rate to unnecessary sensors indicating that our approach is sparsity-promoting, and an effective sensor selection heuristic.     

Forecasting notebook computer price as a function of constituent features

This paper proposes a three-phase approach to forecast a competitive price for a notebook computer as a function of constituent features. Phase I uses regression analysis to relate computer price to constituent features in each of a series of time periods. Phase II involves a time series analysis of each regression coefficient to quantify how trends in market conditions (e.g., the evolution of component technology) affect the market value of each feature. Phase III uses the time series analysis to forecast future market values of each feature and combines these results to forecast a competitive selling price for a notebook model that is composed of a selected set of features. The approach can be used in support of management decisions related to prescribing when to upgrade a notebook model and what features to include in each upgrade. The approach can be used, for example, to forecast notebook model price at introduction, and the rate at which price will erode over the model’s life cycle. Computational results indicate that the approach can forecast the price of a notebook computer model up to four months in advance of its introduction to within 10%. It can also forecast the rate of price erosion to within 10% for up to seven months after introduction — the length of the life cycle of a typical notebook model. Since this approach uses only publicly available data, it can be used easily in industry.     

Requirements Engineering-Based Conceptual Modelling

The software production process involves a set of phases where a clear relationship and smooth transitions between them should be introduced. In this paper, a requirements engineering-based conceptual modelling approach is introduced as a way to improve the quality of the software production process. The aim of this approach is to provide a set of techniques and methods to capture software requirements and to provide a way to move from requirements to a conceptual schema in a traceable way. The approach combines a framework for requirements engineering (TRADE) and a graphical object-oriented method for conceptual modelling and code generation (OO-Method). The intended improvement of the software production process is accomplished by providing a precise methodological guidance to go from the user requirements (represented through the use of the appropriate TRADE techniques) to the conceptual schema that properly represents them (according to the conceptual constructs provided by the OO-Method). Additionally, as the OO-Method provides full model-based code generation features, this combination minimises the time dedicated to obtaining the final software product.     

A cognitive load application in tutoring

Research on intelligent tutoring systems has mainly concentrated on how to reduce a cognitive load which a student will bear in learning a domain. This load reduction approach contributes to facilitating his/her learning. However the approach often fails to reinforce the student's comprehension and retention. Another approach to tutoring is to apply a load to him/her purposefully. In this paper, we present a framework for cognitive load application and describe a demonstration system. The framework imposes a load on a student who tries to understand an explanation. The important point toward the load application is to provide the student with an optimal load that does not go beyond his/her capacity for understanding. This requires controlling the student's load by means of explanations. In order to implement such load control, it is necessary to estimate how much load the explanation imposes on his/her understanding process. The load estimate depends on his/her understanding capability since the same explanation imposes a different load according to the capability. Therefore a student model representing his/her capability is required. This paper shows how our system accomplishes a proper load application by generating explanations with the load estimate.     

Strategic Replication of Video Files in a Distributed Environment

The per service cost has been a serious impediment to wide spread usage of on-line digital continuous media service, especially in the entertainment arena. Although handling continuous media may be achievable due to technology advances in the past few years, its competitiveness in the market with existing service type such as video rental is still in question. In this paper, we propose a model for continuous media service in a distributed infrastructure which has a video warehouse and intermediate storages connected via a high speed communication network, in an effort to reduce the resource requirement to support a set of service requests. The storage resource and network resource to support a set of requests should be properly quantified to a uniform metric to measure the efficiency of the service schedule. We developed a cost model which maps the given service schedule to a quantity. The proposed cost model is used to capture the amortized resource requirement of the schedule and thus to measure the efficiency of the schedule. The distributed environment consists of a massive scale continuous media server called a video warehouse, and intermediate storages connected via a high speed communication network. An intermediate storage is located in each neighborhood, and its main purpose is to avoid the repeated delivery of the same file to a neighborhood. We consider a situation where a request for a video file is made sometime in advance. We develop a scheduling algorithm which strategically replicates the requested continuous media files at the various intermediate storages.