共查询到20条相似文献,搜索用时 15 毫秒
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W. R. Jones 《Software》1971,1(2):159-166
This paper describes how a user of a graphical display unit, e.g. a designer or draftsman, etc. can create procedures at the console which will perform geometric constructions and calculations. These procedures may be recorded, and subsequently recalled and executed, using data values supplied by the user This system may be regarded as an extension to the IBM program Graphic Part Programmer (GPP) Number 360D–23.4.003.1 The basic system utilized is the contruction part of this program which has been extended to provide drafting facilities. No programming courses are needed as no language is involved, and the only prior experience necessary is that needed to become familiar with the drafting system. 相似文献
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B. Meyer 《Computers & Graphics》1979,4(3-4):177-183
This paper describes a system that improves the performance of a time-shared host computer for users of TEKTRONIX series 4010/4014/4015 graphics terminals. The system consists of a mini or microcomputer situated at the terminal, a program that runs in the satellite computer and a library of FORTRAN callable subroutines that provide a convenient interface between an application program in the host computer and the program in the satellite computer. The system ensures that the satellite has advance information about the expected dialogue, so that the satellite is able to react instantly to input from the user, even if the response of the host computer is slow. The satellite gathers several trivial inputs together and sends them to the host in a burst. This allows the program in the host to process more information each time it is rolled into memory, hence the efficiency of its operation is improved. The satellite also performs such operations as zooming, repainting and identification of entities on the screen. 相似文献
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Since the number of server providing the facilities for the user is usually more than one, the authentication protocols for multi-server environment are required for practical applications. Most of password authentication schemes for multi-server environment are based on static ID, so the adversary can use this information to trace and identify the user's requests. It is unfavorable to be applied to special applications, such as e-commerce. In this paper, we develop a secure dynamic ID based remote user authentication scheme to achieve user's anonymity. The proposed scheme only uses hashing functions to implement a robust authentication scheme for the multi-server environment. It provides a secure method to update password without the help of third trusted party. The proposed scheme does not only satisfy all requirements for multi-server environment but also achieve efficient computation. Besides, our scheme provides complete functionality to suit with the real applications. 相似文献
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Seung-Ho Hong Joung-Han Lee 《International Journal of Control, Automation and Systems》2010,8(4):831-840
Field devices in factory automation and process control systems generate time-critical, periodic, and time-available data. These data share the bandwidth of one fieldbus network medium. This paper reviews a bandwidth allocation scheme (BAS) that is applicable to many different kinds of field-buses. The BAS satisfies the real-time transmission requirements of time-critical and periodic data, and fully utilizes the bandwidth resources of the fieldbus network. The basic concept of the BAS is introduced and its implementation in Foundation Fieldbus, Profibus, and CAN protocols is discussed. 相似文献
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A network architecture supporting consistent rich behavior in collaborative interactive applications 总被引:1,自引:0,他引:1
Marsh J Glencross M Pettifer S Hubbold R 《IEEE transactions on visualization and computer graphics》2006,12(3):405-416
Network architectures for collaborative virtual reality have traditionally been dominated by client-server and peer-to-peer approaches, with peer-to-peer strategies typically being favored where minimizing latency is a priority and client-server where consistency is key. With increasingly sophisticated behavior models and the demand for better support for haptics, we argue that neither approach provides sufficient support for these scenarios nor, thus, a hybrid architecture is required. We discuss the relative performance of different distribution strategies in the face of real network conditions and illustrate the problems they face. Finally, we present an architecture that successfully meets many of these challenges and demonstrate its use in a distributed virtual prototyping application which supports simultaneous collaboration for assembly, maintenance, and training applications utilizing haptics. 相似文献
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This paper studies a general strategy to predict voice Quality of Experience (QoE) for various mobile networks. Particularly, based on data-mining for Adaptive Multi-Rate (AMR) codec voice, a novel QoE assessment methodology is proposed. The proposed algorithm consists of two parts. The first part is devoted to assessing speech quality of fixed rate codec mode (CM) of AMR while in the other one a adaptive rate CM is designed. Measuring basic network parameters that have much impact on speech quality, QoE can be monitored in rei time for operators. Meanwhile, based on the measurement data sets from real mobile network, the QoE prediction strategy can be implemented and QoE assessment model for AMR codec voice is trained and tested. Finally, the numerical results suggest that the correlation coefficient between predicted values and true values is greater than 90~0 and root mean squared error is less than 0.5 for fixed and adaptive rate CM. 相似文献
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DIALOG is a collection of routines, including a main ‘driver’ program, which is used by an applications programmer as the user interface to interactive applications programs. The routines handle command analysis, data input and editing, as well as processing standard commands such as HELP. DIALOG offers, with no extra effort from the applications programmer, not only a simple interface for first-time users which gives complete instruction in using the program, but also a ‘command driven’ interface for more experienced users. DIALOG permits the quick and effective production of interactive applications software by programmers with no previous experience of writing such programs. User reaction to the programs so far produced and offered as part of a university computing service has been extremely favourable. 相似文献
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Nong-Kun Chen Author Vitae Jiann-Liang Chen Author Vitae 《Computers & Electrical Engineering》2007,33(3):221-229
Wireless LAN networking is an indispensable technology in an All-IP network architecture to satisfy the “anytime and anywhere” communication requirement of end users. This investigation proposes feedback controllers designing based on dynamic quality-of-service requirement for wireless LAN multimedia services. During the controllers design process, the time-domain is replaced by the s-domain, simplifying the calculation. This work presents three controllers namely proportional integral (PI), proportional derivative (PD) and proportional integral derivative (PID). Experimental results show that systems that employ the proposed controllers can quickly achieve the required system performance. Additionally, the PID controller has the best performance, and can improve delay performance by a rate 11.44% that without the feedback controller. The PI controller is superior to the PD controller. The delay when using the PD is 6.2% less than that achieved without the feedback controller. 相似文献
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Brian Beckman 《Software》1991,21(2):187-207
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Yasuo Ebara 《Artificial Life and Robotics》2013,17(3-4):483-487
In remote collaborative work via WAN, sharing and recognizing various high-quality visual contents such as photography, visualization image, and real video streaming is extremely important. Supporting a high-quality display of these contents on a large-scale display system is necessary to support intellectual remote collaborative work. However, these contents are currently magnified in low resolution on a general projector used as large-sized display equipment, and these equipments are difficult to display the contents with sufficient quality. In this paper, we have focused on the tiled display wall technology which configure a wide-area screen with two or more LCD and tried to display realistic high-resolution visual contents to solve these issues. We have constructed a tele-immersive environment with a tiled display wall, and have studied the availability for intuitive remote collaborative work by implementing various collaborative applications for the effective display of high-resolution contents as well as developing interaction techniques for enormous visual contents in this environment. As a result, we have showed that the practical use of a tiled display wall is useful in the construction of intellectual remote collaborative environment. 相似文献
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Fang-Yie Leu 《Journal of Network and Computer Applications》2009,32(5):1073-1091
In a heterogeneous wireless environment, seamless mobility is the basis of network support with which mobile users who roam between or among various wireless access networks are able to fully enjoy uninterrupted wireless services. When users are in a mass transportation vehicle, e.g., a bus or a train that provides network service, the vehicle can be regarded as a network which is serving users as it moves from one location to another. The movement of a network is called network mobility (NEMO). The network mobility protocol based on Mobile IPv6 as proposed by the Internet Engineering Task Force (IETF) in 2005 has some fundamental drawbacks, such as header overhead and the pinball problem. In this paper, we propose a novel hybrid method for network mobility called Hybrid-NEMO, which provides a soft handoff scheme at the transport layer basically utilizing SIP and SCTP protocols to ensure a lossless packet-transmission environment and less handoff-delay variation, which are critical in providing QoS voice and multimedia applications. Experimental validation and performance evaluation were also conducted in this study. 相似文献
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Cheng-Chi Lee Tsung-Hung Lin Rui-Xiang Chang 《Expert systems with applications》2011,38(11):13863-13870
Recently, Hsiang et al. pointed out that Liao-Wang’s dynamic ID based remote user authentication scheme for multi-server environment is vulnerable to insider attack, masquerade attack, server spoofing attack, registration center attack and is not easily reparable. Besides, Liao-Wang’s scheme cannot achieve mutual authentication. For this, Hsiang et al. proposed an improved scheme to overcome these weaknesses and claimed that their scheme is efficient, secure, and suitable for the practical application environment. However, we observe that Hsiang et al.’s scheme is still vulnerable to a masquerade attack, server spoofing attack, and is not easily reparable. Furthermore, it cannot provide mutual authentication. Therefore, in this paper we propose an improved scheme to solve these weaknesses. 相似文献
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针对Li等人基于智能卡的多服务器身份认证方案,分析指出了其中存在的安全性问题,提出了一个改进的双因素动态身份鉴别方案.该方案为用户提供了一种关于身份注册信息的自我更新机制,用户可以在不与远程服务器通信的状态下,动态更新身份标志、口令和秘密参数等相关信息.另外,自验证的时间戳技术的借鉴利用,不仅避免了时钟同步问题,而且节约了产生随机数的开销.该方案还实现了用户的动态登录和对用户登录操作的可追踪性.新方案不仅继承了Li方案计算量低、存储量小的优点,而且还提高了认证方案的安全性和实用性,可以适用于实际的网络环境和应用. 相似文献
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Recent results in neural network research have demonstrated their utility in a variety of application areas. Neural networks are able to achieve a very high performance, and classification accuracy in real world applications such as handwritten character recognition, remote sensing images, vision, robotic. Network performance greatly depends not only on the input/output data, but also on its architecture. Most of neural network applications have been developed using anad hoc approach resulting in poor efficiency and performance. In this paper, a development method of neural network applications is presented, and illustrated with a neural classifier of remote sensing images. It is shown how to create in an iterative way a neural classifier architecture, and how to refine a network organization using performance evaluation criteria. 相似文献
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Automatic initialization and tracking of multiple people and their body parts is one of the first steps in designing interactive multimedia applications. The key problems in this context are robust detection and tracking of people and their body parts in an unconstrained environment. This paper presents an integrated framework to address detection and tracking of multiple objects in a computationally efficient manner. In particular, a neural network-based face detector was employed to detect faces and compute person specific statistical model for skin color from the face regions. A probabilistic model was proposed to fuse the color and motion information to localize the moving body parts (hands). Multiple hypothesis tracking (MHT) algorithm was adopted to track face and hands. In real world scenes extracted features (face and hands) usually contain spurious measurements that create unconvincing trajectories and needless computations. To deal with this problem a path coherence function was incorporated along with MHT to reduce the number of hypotheses, which in turn reduces the computational cost and improves the structure of trajectories. The performance of the framework was validated using experiments on synthetic and real sequence of images. 相似文献
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Allocation of bandwidth among components is a fundamental problem in compositional real-time systems. State-of-the-art algorithms
for bandwidth allocation use either exponential-time or pseudo-polynomial-time techniques for exact allocation, or linear-time,
utilization-based techniques which may over-provision bandwidth. In this paper, we propose research into a third possible
approach: parametric approximation algorithms for bandwidth allocation in compositional real-time systems. We develop a fully-polynomial-time
approximation scheme (FPTAS) for allocating bandwidth for sporadic task systems scheduled by earliest-deadline first (EDF)
upon an Explicit-Deadline Periodic (EDP) resource. Our algorithm takes, as parameters, the task system and an accuracy parameter
ϵ>0, and returns a bandwidth which is guaranteed to be at most a factor (1+ϵ) more than the optimal minimum bandwidth required to successfully schedule the task system. Furthermore, the algorithm has
time complexity that is polynomial in the number of tasks and 1/ϵ. 相似文献
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Hsiang-Fu Yu Hung-Chang Yang Yao-Tien Wang Ping-Lin Fan Chu-Yi Chien 《Multimedia Tools and Applications》2009,42(3):295-316
Efficient data broadcasting is independent of request arrivals, and is thus highly promising when transmitting popular videos.
A conventionally adopted broadcasting method is periodic broadcasting, which divides a popular video into segments, which
are then simultaneously broadcast on different data channels. Once clients want to watch the video, they download the segments
from these channels. The skyscraper broadcasting (SkB) scheme supports clients with small bandwidths. An SkB client requires
only two-channel bandwidths to receive video segments. This work proposes a reverse SkB (RSkB) scheme, which extends SkB by
reducing buffering spaces. The RSkB is mathematically shown to achieve on-time video delivery and two-channel client bandwidths.
A formula for determining the maximum number of segments buffered by an RSkB client is presented. Finally, an analysis of
RSkB reveals that its client buffer requirements are usually 25–37% lower than SkB. Extensive simulations of RSkB further
demonstrate that RSkB yields lower client buffer demand than other proposed systems.
相似文献
Hsiang-Fu YuEmail: |
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Network-based concurrent computing and interactive data visualization are two important components in industry applications of high-performance computing and communication. We propose an execution framework to build interactive remote visualization systems for real-world applications on heterogeneous parallel and distributed computers. Using a dataflow model of a commercial visualization software AVS in three case studies, we demonstrate a simple, effective, and modular approach to couple parallel simulation modules into an interactive remote visualization environment. The applications described in this paper are drawn from our industrial projects in financial modeling, computational electromagnetics and computational chemistry. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献