Network coding theory: An introduction

For a long time, store-and-forward had been the transport mode in network communications. In other words, information had been regarded as a commodity that only needs to be routed through the network, possibly with replication at the intermediate nodes. In the late 1990’s, a new concept called network coding fundamentally changed the way a network can be operated. Under the paradigm of network coding, information can be processed within the network for the purpose of transmission. It was demonstrated that compared with store-and-forward, the network throughput can generally be increased by employing network coding. Since then, network coding has made significant impact on different branches of information science. The impact of network coding has gone as far as mathematics, physics, and biology. This expository work aims to be an introduction to this fast-growing subject with a detailed discussion of the basic theoretical results.     

β-Selective C−H Arylation of Electron-Deficient Thiophenes,Pyrroles, and Furans

A general β-C−H arylation of electron-deficient thiophenes, pyrroles, and furans has been developed using ligand-modulated palladium catalyst. The use of a modified norbornene is crucial for reversing the conventional α-selectivity of these substrates. This method features good yields, high β-selectivity, and good tolerance of functional groups.     

Limits of accuracy of dyeing process control and dyeing quality

In this study, a previously-developed numerical prediction model of colour sensitivity for disperse dye recipes was applied to predict the limit of accuracy in the control of dyeing processes according to a certain colour tolerance for individual recipes. The results confirmed that both concentration and temperature were the most important factors affecting dyeing results.     

Developing a Fuzzy Risk Allocation Model for PPP Projects in China

Equitable allocation of risks between the government and the private sector in concession agreement is essential to the success of public-private partnership (PPP) projects. The decision-making process, based on the established risk allocation principles expressed in linguistic terms, requires qualitative judgment and experiential knowledge of construction experts. However, it is subjective, partial, and implicit in actual application. This paper aims to develop a fuzzy synthetic evaluation model for determining an equitable risk allocation between the government and the private sector. By doing so, it assists the PPP project practitioners to transform the risk allocation principles in linguistic terms into a more usable and systematic quantitative-based analysis using fuzzy set. Twenty-three principles and influencing factors for risk allocation were identified through a comprehensive literature review. Nine critical risk allocation criteria (RACs) that evaluate the risk carrying capability of project participants were further identified, validated, and compiled based on the experts’ knowledge via face-to-face interviews. On the other hand, the weighting for each critical risk allocation criterion was determined through a two-round Delphi questionnaire survey. A set of knowledge-based fuzzy inference rules was then established to set up the membership function for the nine RACs. Based on the research findings, a fuzzy synthetic evaluation model was finally established to determine an equitable risk allocation between the government and the private sector.     

Chemical Signals of Synthetic Disaccharide Derivatives Dominate Rhamnolipids at Controlling Multiple Bacterial Activities

Microbes secrete molecules that modify their environment. Here, we demonstrate a class of synthetic disaccharide derivatives (DSDs) that mimics and dominates the activity of naturally secreted rhamnolipids by Pseudomonas aeruginosa. The DSDs exhibit the dual function of activating and inhibiting the swarming motility through a concentration‐dependent activity reversal that is characteristic of signaling molecules. Whereas DSDs tethered with a saturated farnesyl group exhibit inhibition of both biofilm formation and swarming motility, with higher activities than rhamnolipids, a saturated farnesyl tethered with a sulfonate group only inhibits swarming motility but promote biofilm formation. These results identified important structural elements for controlling swarming motility, biofilm formation, and bacterial adhesion and suggest an effective chemical approach to control intertwined signaling processes that are important for biofilm formation and motilities.     

Approximations and reducts with covering generalized rough sets

The covering generalized rough sets are an improvement of traditional rough set model to deal with more complex practical problems which the traditional one cannot handle. It is well known that any generalization of traditional rough set theory should first have practical applied background and two important theoretical issues must be addressed. The first one is to present reasonable definitions of set approximations, and the second one is to develop reasonable algorithms for attributes reduct. The existing covering generalized rough sets, however, mainly pay attention to constructing approximation operators. The ideas of constructing lower approximations are similar but the ideas of constructing upper approximations are different and they all seem to be unreasonable. Furthermore, less effort has been put on the discussion of the applied background and the attributes reduct of covering generalized rough sets. In this paper we concentrate our discussion on the above two issues. We first discuss the applied background of covering generalized rough sets by proposing three kinds of datasets which the traditional rough sets cannot handle and improve the definition of upper approximation for covering generalized rough sets to make it more reasonable than the existing ones. Then we study the attributes reduct with covering generalized rough sets and present an algorithm by using discernibility matrix to compute all the attributes reducts with covering generalized rough sets. With these discussions we can set up a basic foundation of the covering generalized rough set theory and broaden its applications.     

通过全局核降低高斯核的局部风险与基于遗传算法的两阶段模型选择

支持向量分类时,由于样本分布的不均匀性,单宽度的高斯核会在空间的稠密区域产生过学习现象,在稀疏区域产生欠学习现象,即存在局部风险.针对于此,构造了一个全局性次核来降低高斯核产生的局部风险.形成的混合核称为主次核.利用幂级数构造性地给出并证明了主次核的正定性条件,进一步提出了基于遗传算法的两阶段模型选择算法来优化主次核的参数.实验验证了主次核和模型选择法的优越性.     

A multi-faceted and automatic knowledge elicitation system (MAKES) for managing unstructured information

Management of unstructured information, such as emails, is vital for supporting knowledge work in professional services. However, the conventional way for managing unstructured information is inadequate as the knowledge work and associated tasks are becoming more complex, are dynamically changing with time and involve multiple concepts. This paper attempts to address the inadequacy, deficiency and limitations of the methods presently used to elicit knowledge from masses of unstructured information. These methods rely heavily on manpower, are time consuming and costly. With the development of a multi-faceted and automatic knowledge elicitation system (MAKES) manpower, time and cost can be dramatically reduced. The MAKES integrates the processes of collecting data, classifying unstructured information, modelling knowledge flow and social network analysis, and makes all of these actions into a connected process to audit unstructured information automatically. This audit is based on specific search criteria, search keywords, and the user behaviours of the knowledge workers. The unstructured information is automatically organized, classified and presented in a multi-facet taxonomy map. New concepts and knowledge are uncovered, analyzed and updated continuously from the incoming unstructured information, using a purpose-built knowledge elicitation algorithm named self-associated concept mapping (SACM). The capability and advantages of the MAKES are demonstrated through a successful trial implementation and a verification test conducted in an electronics trading company. Encouraging results have been achieved and a number of potential advantages have been realized. The area of application in this first deployment is based on an email-intensive organization and the proposed study will contribute to the advancement of methods and tools for managing other kinds of unstructured information.