聚合物冷拉过程的流函数分析

用流函数法分析了聚合物拉伸成形时，颈缩的发生和扩展过程，文中论证了采用流函数法的优越性和适用性，并将流函数法计算结果和有限元法计算结果作了对比。     

Co-evolution as a computational and cognitive model of design

Co-evolutionary design has been developed as a computational model that assumes two parallel search spaces: the problem space and the solution space. The design process iteratively searches each space using the other space as the basis for a fitness function when evaluating the alternatives. Co-evolutionary design can also be developed as a cognitive model of design by characterizing the way in which designers iteratively search for a design solution, making revisions to the problem specification. This paper presents the computational model of co-evolutionary design and then describes a protocol study of human designers looking for evidence of co-evolution of problem specifications and design solutions. The study shows that co-evolutionary design is a good cognitive model of design and highlights the similarities and differences between the computational model and the cognitive model. The results show that the two kinds of co-evolutionary design complement each other, having strengths in different aspects of the design process. Electronic Publication     

Secure Multi-Party Computation without Agreement

It has recently been shown that authenticated Byzantine agreement, in which more than a third of the parties are corrupted, cannot be securely realized under concurrent or parallel (stateless) composition. This result puts into question any usage of authenticated Byzantine agreement in a setting where many executions take place. In particular, this is true for the whole body of work of secure multi-party protocols in the case that a third or more of the parties are corrupted. This is because these protocols strongly rely on the extensive use of a broadcast channel, which is in turn realized using authenticated Byzantine agreement. We remark that it was accepted folklore that the use of a broadcast channel (or authenticated Byzantine agreement) is actually essential for achieving meaningful secure multi-party computation whenever a third or more of the parties are corrupted. In this paper we show that this folklore is false. We present a mild relaxation of the definition of secure computation allowing abort. Our new definition captures all the central security issues of secure computation, including privacy, correctness and independence of inputs. However, the novelty of the definition is in decoupling the issue of agreement from these issues. We then show that this relaxation suffices for achieving secure computation in a point-to-point network. That is, we show that secure multi-party computation for this definition can be achieved for any number of corrupted parties and without a broadcast channel (or trusted pre-processing phase as required for running authenticated Byzantine agreement). Furthermore, this is achieved by just replacing the broadcast channel in known protocols with a very simple and efficient echo-broadcast protocol. An important corollary of our result is the ability to obtain multi-party protocols that remain secure under composition, without assuming a broadcast channel.     

智能同步光网络与多业务传送平台的应用

智能同步光网络(ASON)与多业务传送平台(MSTP)固其先进的智能性、可靠性、灵活性而得以发展和运用。本文根据智能光网络与多业务传送平台枝术的发展情况，结合北京通信传送网络的实际情况，探讨北京通信传送网的建设思路．     

Automatic coding of dialogue acts in collaboration protocols

Although protocol analysis can be an important tool for researchers to investigate the process of collaboration and communication, the use of this method of analysis can be time consuming. Hence, an automatic coding procedure for coding dialogue acts was developed. This procedure helps to determine the communicative function of messages in online discussions by recognizing discourse markers and cue phrases in the utterances. Five main communicative functions are distinguished: argumentative, responsive, informative, elicitative, and imperative. A total of 29 different dialogue acts are specified and recognized automatically in collaboration protocols. The reliability of the automatic coding procedure was determined by comparing automatically coded dialogue acts to hand-coded dialogue acts by a human rater. The validity of the automatic coding procedure was examined using three different types of analyses. First, an examination of group differences was used (dialogue acts used by female versus male students). Ideally, the coding procedure should be able to distinguish between groups who are likely to communicate differently. Second, to examine the validity of the automatic coding procedure through examination of experimental intervention, the results of the automatic coding procedure of students, with access to a tool that visualizes the degree of participation of each student, were compared to students who did not have access to this tool. Finally, the validity of the automatic coding procedure of dialogue acts was examined using correlation analyses. Results of the automatic coding procedure of dialogue acts of utterances (form) were related to results of a manual coding procedure of the collaborative activities to which the utterances refer (content). The analyses presented in this paper indicate promising results concerning the reliability and validity of the automatic coding procedure for dialogue acts. However, limitations of the procedure were also found and discussed.     

MPEG-2解码器中视频、音频同步的实现

本文分析了理想的MPEG－2信源解码器中视频、音频同步实现的关键，给出了实际的解码器中实现视频、音频同步会遇到的问题和解决的方法。实践证明，这些方法是有效的，已用于我们的MPEG-2信源解码器中。     

Adding Support for Persistence to CLOS via Its Metaobject Protocol

Language-level support for object persistence frees programmers from having to confront a broad class of database issues from within their applications. By virtue of its metaobject protocol, CLOS is a language whose semantics can be tailored by individual programmers. We used the metaobject protocol to extend CLOS with support for object persistence. Our goal was to obtain a version of CLOS with persistence to which we could easily port a commercial geometric CAD modeling system. We describe the design and implementation of our persistence extension and highlight the strengths and weaknesses exhibited by the CLOS metaobject protocol during our experiment. For many aspects of the implementation we found that the metaobject protocol was ideal. In other cases we had to choose among paying a large performance penalty, extending the protocol, and bypassing the protocol by modifying the language implementation directly.     

Optimal Conditions for Preparing Ultra-Fine CeO2 Powders in A Submerged Circulative Impinging Stream Reactor

Cerium carbonate powders were produced in a submerged circulation impinging stream reactor (SCISR) from Ce(NO3)3·6H2O. NH4HCO3 was used as a precipitant in the reaction. Cerium carbonate powders were roasted to produce ultra-fine cerium dioxide (CeO2) powders. The optimal conditions of such production process were obtained by orthogonal and one-factor experiments. The results showed that ultra-fine and narrowly distributed cerium carbonate powders were produced under the optimal flowing conditions. The concentrations of Ce(NO3)3 and NH4HCO3 solutions were 0.25 and 0.3 mol·L-1, respectively. The concentration of PEG4000 added in these two solutions was 4 g·L-1. The stirring ratio, reaction temperature, feeding time, solution pH, reaction time and digestion time were 900 r·min-1, 80 ℃, 20 min, 5～6, 5 min and 1 h, respectively. The final product, CeO2 powders, was obtained by roasting the produced cerium carbonate in air for 3 h at 500 ℃. The finally produced CeO2 powders were torispherical particles with a narrow size distribution of 0.8～2.5 μm. The crystal structure of CeO2 powders belonged to cubic crystal system and its space point group was O5H-FM3M. Under optimal conditions, powders produced by SCISR were finer and more narrowly distributed than that by Stirred Tank Reactor (STR).     

基于TCP／IP的水利试验测控系统设计

本文介绍一种基于TCP／1P协议的新型水力物理模型试验测控系统，该系统将目前最先进、最流行的工业以太网技术应用到物理模型试验研究的测控系统中，实现多点水位、流速和流量等水力学重要参数的实时采集、处理、储存、显示及打印，并具有在线查询及数据分析功能。     

The Tenet experience and the design of protocols for integrated-services internetworks

The research done by the Tenet Group in multimedia networking has reached a point where it may be useful to reflect on the significance of its results for the current debate on how integrated-services internetworks should be designed. Such reflections constitute the main subject of this paper. The principles of the work and the conclusions reached so far by the Tenet researchers are discussed in the light of the conflict between the two major technologies being proposed to build future information infrastructures: namely, the Internet and the ATM technologies. The Tenet approach suggests one feasible way for resolving the conflict to the advantage of all the users of those infrastructures. This paper discusses various fundamental aspects of integrated-services network design: the choice of the service model, the type of charging policy to be adopted, and the selection of a suitable architecture.