船用8缸柴油机不同排气系统设计及性能研究

针对直列8缸船用柴油机高负荷排气温差较高的问题,分析了原因,研究了混合式脉冲转换(MIXPC)增压系统降低最大排气温差的主要途径,设计了一种混合模件排气(Hybrid Modular Exhaust)系统,探讨了HME、MIXPC和多功能脉冲转换器(MMPC)三种不同排气系统的性能。结果表明:MMPC系统高负荷排气温差较高的主要原因是上游压力波动影响下游扫气过程;MIXPC系统通过增加第7缸支管出口与第8缸支管出口面积比,可以降低最大排气温差,改善发动机排温不均匀性;采用HME增压系统可以有效降低扫气干扰,在改动较小以及不改变整机性能的前提下,最大排气温差降低29°C,排气温度不均匀性得到明显改善。

模件化设计方法对中国文字再设计的启发

中国的汉字系统是一种典型的模件化系统。模件化系统不仅作为汉字构造的基础而存在,而且利用这个系统可以将原有的汉字进行再设计与创新,启发文字设计的新形式,同时汉字研究对提升设计水平也同样有重要意义。因此,本文着重对中国汉字系统的模件化设计方法进行梳理,并对中国文字模件化设计案例和古代书法家与当代设计师的相关案例展开探讨,以示模件化设计方法的普遍性与有效性。

MODELING METHOD FOR CROSSCUTTING CONCERNS IN CONCURRENT SOFTWARE SYSTEM

A method for modeling crosscutting concerns in the concurrent software system is presented based on the aspect-oriented（A-O） technique and the statechart of unified modeling language （UML）. Modeled with UML statechart diagrams, the primary system functions and corresponding traversal features are enveloped into various orthogonal regions of a composite state. The mutual relationships between orthogonal regions are implied by the orders of broadcast events. Using a modular transition system as a basic computational model, the formalization description of A-O statechart models is proposed. The precise semantics of model elements and modeling procedures is given. The example study indicates that the separation strategy of crosscutting concerns is implemented in the design phase of the concurrent software system with this method. Meanwhile, the software modeling method has advantages of loose coupling, adaptability and traceability.

Design and Study of a High Security ATM System

Based on the characteristics of ATM system and the special requirement of financial transaction, an overall design of hardware and software structure of ATM was made. For software structure, the pattern of modules and table? drive is adopted to realize the security of financial transaction and the diagnosis of communication fault. A new method, which is based on the application layer, transport layer and network layer, is used for diagnosing communication fault. Supporting both magnetic card and IC card, the system has been put into use in real financial systems, and has brought about both economic and social effects.

黄梅挑花图案的模件系统

黄梅挑花经由一代代绣娘们的传承,发展出一套连接历史并承载社会价值的装饰系统。其图案的创造在历史演变中既保持了固定不变的成分,又发展出细节上的变异。究其原因,这与其图案中所贯穿的模件系统密切相关。本文拟从这一视角出发,审视绣娘们如何对过去的设计元素进行重复与变换,以及在标准化模件基础上添加个人的主动创造。这一图案的再造与更新方法对于当下的手工艺实践不乏借鉴意义。

Evaluation model for freeway incident management system

In order to evaluate the general situation and find special problems of the freeway incident management system, an evaluation model is proposed. First, the expert appraisal approach is used to select the primary evaluation index. As a result, 81 indices and the hierarchical structures of the index such as the object layer, the sub-object layer, the criterion layer and the index layer are determined. Then, based on the fuzzy characteristics of each index layer, the analytical hierarchy process（AHP）and the fuzzy comprehensive evaluation are applied to generate the weight and the satisfaction of the index and the criterion layers. When analyzing the relationship between the sub-object layer and the object layer, it is easy to find that the number of sub-objects is too large and sub-objects are significantly redundant. The partial least square （PLS） is proposed to solve the problems. Finally, an application example, whose result has already been accepted and employed as the indication of a new project in improving incident management, is introduced and the result verifies the feasibility and efficiency of the model.

Reliability Assessment of Distribution SystemBased on Discrete-event System

Discrete-event system simulation technology is used to analyze distribution system reliability in this paper. A simulation model, including entity state models, system state models, state transition models, reliability criterion model, is established. ‘Next happen event’ is taken as impulse principle of simulator clock to determine the sequence of random event occurrence dynamically. The results show this method is feasible.

Drought Impacts on Vegetation Indices and Productivity of Terrestrial Ecosystems in Southwestern China During 2001–2012

Drought, as a recurring extreme climate event, affects the structure, function, and process of terrestrial ecosystems. Despite the increasing occurrence and intensity of the drought in the past decade in Southwestern China, the impacts of continuous drought events on vegetation in this region remain unclear. During 2001–2012, Southwestern China experienced the severe drought events from 2009 to 2011. Our aim is to characterize drought conditions in the Southwestern China and explore the impacts on the vegetation condition and terrestrial ecosystem productivity. The Standardized Precipitation Index(SPI) was used to characterize drought area and intensity and a light-use efficiency model was used to explore the effect of drought on the terrestrial ecosystem productivity with Moderate Resolution Imaging Spectrometer(MODIS) data. The SPI captured the major drought events in Southwestern China during the study period, indicated that the 12-year period of this study included both ‘normal' precipitation years and two severe drought events in 2009–2010 and 2011. Results showed that vegetation greenness(Normalized Difference Vegetation Index, NDVI and Enhanced Vegetation Index, EVI) both declined in 2009/2010 drought, but the 2011 drought resulted in less declines of vegetation greenness and productivity due to shorten drought duration and rising temperature. Meanwhile, it was about 5 months lapse between drought events and maximum declines in vegetation greenness for 2009/2010 drought events. In addition, forest, grassland and cropland revealed significant different ecosystem responses to drought. It indicated that grassland showed an early sensitivity to drought, while cropland was the most sensitive to water deficit and forest was more resilient to drought. This study suggests that it is necessary to detect the difference responses of ecosystem to drought in a regional area with satellite data and ecosystem model.

The practice of mine ventilation engineering

The practice of ventilation is continually evolving with new technological advances developed in the mining industry.In recent years the advances in diesel engine technologies,ventilation modeling software,and ventilation management capacities have redefined the historical methods used to evaluate systems.The advances re-evaluate previous methods used to calculate the airflow requirements for the dilution of diesel exhaust fumes.Modeling software has become an integral part of planning and developing ventilation systems in partnership with graphical mine design software packages to generate realistic representations of the mine.Significant advances in ventilation control strategies through remote sensors and monitoring capabilities have been developed to results in cost savings.Though there has been much advancement in mine ventilation technology,the practices and basic ventilation principals enacted through the ventilation engineer cannot be placated with technological advances only.

（Dis）Economies of Scale in Business Software Systems Development and Enhancement Projects

In the software engineering literature, it is commonly believed that economies of scale do not occur in case of software Development and Enhancement Projects （D＆EP）. Their per-unit cost does not decrease but increase with the growth of such projects product size. Thus this is diseconomies of scale that occur in them. The significance of this phenomenon results from the fact that it is commonly considered to be one of the fundamental objective causes of their low effectiveness. This is of particular significance with regard to Business Software Systems （BSS） D＆EP characterized by exceptionally low effectiveness comparing to other software D＆EP. Thus the paper aims at answering the following two questions： （1） Do economies of scale really not occur in BSS D＆EP？ （2） If economies of scale may occur in BSS D＆EP, what factors are then promoting them？ These issues classify into economics problems of software engineering research and practice.

New sufficient conditions for general linear SISO Takagi-Sugeno fuzzy systems as universal approximators

By the best approximation theory, it is first proved that the SISO （single-input single-output） linear Takagi-Sugeno （TS） fuzzy systems can approximate an arbitrary polynomial which, according to Weierstrass approximation theorem, can uniformly approximate any continuous functions on the compact domain. Then new sufficient conditions for general linear SISO TS fuzzy systems as universal approximators are obtained. Formulae are derived to calculate the number of input fuzzy sets to satisfy the given approximation accuracy. Then the presented result is compared with the existing literature＇s results. The comparison shows that the presented result needs less input fuzzy sets, which can simplify the design of the fuzzy system, and examples are given to show its effectiveness.

A neurofuzzy system based on rough set theory and genetic algorithm

This paper presents a hybrid soft computing modeling approach for a neurofuzzy system based on rough set theory and the genetic algorithms (NFRSGA). The fundamental problem of a neurofuzzy system is that when the input dimension increases, the fuzzy rule base increases exponentially. This leads to a huge infrastructure network which results in slow convergence. To solve this problem, rough set theory is used to obtain the reductive rules, which are used as fuzzy rules of the fuzzy system. The number of rules decrease, and each rule does not need all the conditional attribute values. This results in a reduced, or not fully connected, neural network. The structure of the neural network is relatively small and thus the weights to be trained decrease. The genetic algorithm is used to search the optimal discretization of the continuous attributes. The NFRSGA approach has been applied in the practical application of building a soft sensor model for estimating the freezing point of the light diesel fuel in a Fluid Catalytic Cracking Unit (FCCU), and satisfying results are obtained.

Thermal-Fluid Coupling Simulation of Ventilation Cooling System of Generator Based on FLOWMASTER

By taking a 2.3 MW double-fed asynchronous generator as an example,a new method for fast simulation analysis of ventilation cooling system inside generator is proposed based on the one-dimensional simulation software FLOWMASTER.The thermal-fluid coupling simulation model of ventilation cooling system inside generator is established.Under the stable running state of the generator,the flow velocity distribution and temperature rise of the key parts of the generator are analyzed.The results prove that the ventilation structure design of the generator meets the temperature rise limit.The simulation results are compared with the theoretical calculation results and the experimental results,which verify the correctness of the thermal-fluid coupling simulation method proposed in this paper.

MODEL-BASED PERFORMANCE EVALUATION APPROACH FOR MOBILE AGENT SYSTEMS

Claimed as the next generation programming paradigm, mobile agent technology has attracted extensive interests in recent years. However, up to now, limited research efforts have been devoted to the performance study of mobile agent system and most of these researches focus on agent behavior analysis resulting in that models are hard to apply to mobile agent systems. To bridge the gap, a new performance evaluation model derived from operation mechanisms of mobile agent platforms is proposed. Details are discussed for the design of companion simulation software, which can provide the system performance such as response time of platform to mobile agent. Further investigation is followed on the determination of model parameters. Finally comparison is made between the model-based simulation results and measurement-based real performance of mobile agent systems. The results show that the proposed model and designed software are effective in evaluating performance characteristics of mobile agent systems. The proposed approach can also be considered as the basis of performance analysis for large systems composed of multiple mobile agent platforms.

Exploring proximity based peer clustering in BitTorrent-like Peer-to-Peer file sharing systems

A hierarchical clustered BitTorrent （CBT） system is proposed to improve the file sharing perior-mance of the BitTorrent system, in which peers are grouped into clusters in a large-scale BitTorrent-hke underlying overlay network in such a way that clusters are evenly distributed and that the peers within the cluster are relatively close to each other. A fluid model is developed to compare the performance of the proposed CBT system with the BitTorrent system, and the result shows that the CBT system can effectively improve the performance of the system. Simulation results also demonstrate that the CBT system improves the system scalabihty and efficiency while retaining the robustness and incentives of the original BitTorrent paradigm.

An Orthogonal Approach to Reusable Component Discovery in Cloud Migration

As an innovative software application mode,Software as a service(SaaS) shows many attractive advantages.Migrating legacy system to SaaS can make outdated systems revived.In the process of migration,the existing valuable components need to be discovered and reused in order that the target system could be developed/integrated more efficiently.An innovative approach is proposed in this paper to extract the reusable components from legacy systems.Firstly,implementation models of legacy system are recovered through reverse engineering.Secondly,function models are derived by vertical clustering,and then logical components are discovered by horizontal clustering based on the function models.Finally,the reusable components with specific feature descriptions are extracted.Through experimental verification,the approach is considered to be efficient in reusable component discovery and to be helpful to migrating legacy system to SaaS.

A role based coordination model in agent systems

Coordination technology addresses the construction of open, flexible systems from active and independent software agents in concurrent and distributed systems. In most open distributed applications, multiple agents need interaction and communication to achieve their overall goal. Coordination technologies for the Internet typically are concerned with enabling interaction among agents and helping them cooperate with each other. At the same time, access control should also be considered to constrain interaction to make it harmless. Access control should be regarded as the security counterpart of coordination. At present, the combination of coordination and access control remains an open problem. Thus, we propose a role Dased coordination model with policy enforcement in agent application systems. In this model, coordination is combined with access control so as to fully characterize the interactions in agent systems. A set of agents interacting with each other for a common global system task constitutes a coordination group. Role based access control is applied in this model to prevent unauthorized accesses. Coordination policy is enforced in a distributed manner so that the model can be applied to the open distributed systems such as Internet. An Internet online auction system is presented as a case study to illustrate the proposed coordination model and finally the performance analysis of the model is introduced.