Binomial filters

Binomial filters are simple and efficient structures based on the binomial coefficients for implementing Gaussian filtering. They do not require multipliers and can therefore be implemented efficiently in programmable hardware. There are many possible variations of the basic binomial filter structure, and they provide a wide range of space-time trade-offs; a number of these designs have been captured in a parametrised form and their features are compared. This technique can be used for multi-dimensional filtering, provided that the filter is separable. The numerical performance of binomial filters, and their implementation using field-programmable devices for an image processing application, are also discussed.     

Bilingual legal document retrieval and management using XML

In certain bilingual and multi‐lingual societies, translated legal documents are as important as the original legal documents because they have the same legal status as the originals. However, there is little reported work on the retrieval and management of bilingual legal documents. We describe the design and development of a bilingual document retrieval and management prototype, called ELDoS, which is used by court interpreters and judges from the Hong Kong Judiciary. Since the speed of retrieval is a major concern for user acceptance, and therefore for widespread deployment of the system, the architecture of the prototype is designed to balance the workload of the client and server. Extensible Markup Language (XML) is used to mark up the bilingual legal documents for a variety of document retrieval and management tasks. XML enables the use of XML Stylesheet Language Transformation (XSLT) to align bilingual data in the client, instead of the server, and improve alignment speed linearly with respect to the size of the document, using a high‐end PC, when the server has no concurrent access. The design of the interface was continually improved after extensive consultation with court interpreters and after the user acceptance tests. In our evaluation, the facilities for highlighting translated terms have a macro‐averaged precision of 90+% and a macro‐average recall of 80+%, which were considered acceptable by our users. We believe that the experience in the design and development of this prototype is applicable to other language pairs as well as to other domains. Copyright © 2002 John Wiley & Sons, Ltd.     

Representing financial time series based on data point importance

Recently, the increasing use of time series data has initiated various research and development attempts in the field of data and knowledge management. Time series data is characterized as large in data size, high dimensionality and update continuously. Moreover, the time series data is always considered as a whole instead of individual numerical fields. Indeed, a large set of time series data is from stock market. Stock time series has its own characteristics over other time series. Moreover, dimensionality reduction is an essential step before many time series analysis and mining tasks. For these reasons, research is prompted to augment existing technologies and build new representation to manage financial time series data. In this paper, financial time series is represented according to the importance of the data points. With the concept of data point importance, a tree data structure, which supports incremental updating, is proposed to represent the time series and an access method for retrieving the time series data point from the tree, which is according to their order of importance, is introduced. This technique is capable to present the time series in different levels of detail and facilitate multi-resolution dimensionality reduction of the time series data. In this paper, different data point importance evaluation methods, a new updating method and two dimensionality reduction approaches are proposed and evaluated by a series of experiments. Finally, the application of the proposed representation on mobile environment is demonstrated.     

Custom parallel caching schemes for hardware-accelerated image compression

In an effort to achieve lower bandwidth requirements, video compression algorithms have become increasingly complex. Consequently, the deployment of these algorithms on field programmable gate arrays (FPGAs) is becoming increasingly desirable, because of the computational parallelism on these platforms as well as the measure of flexibility afforded to designers. Typically, video data are stored in large and slow external memory arrays, but the impact of the memory access bottleneck may be reduced by buffering frequently used data in fast on-chip memories. The order of the memory accesses, resulting from many compression algorithms are dependent on the input data (Jain in Proceedings of the IEEE, pp. 349–389, 1981). These data-dependent memory accesses complicate the exploitation of data re-use, and subsequently reduce the extent to which an application may be accelerated. In this paper, we present a hybrid memory sub-system which is able to capture data re-use effectively in spite of data-dependent memory accesses. This memory sub-system is made up of a custom parallel cache and a scratchpad memory. Further, the framework is capable of exploiting 2D spatial locality, which is frequently exhibited in the access patterns of image processing applications. In a case study involving the quad-tree structured pulse code modulation (QSDPCM) application, the impact of data dependence on memory accesses is shown to be significant. In comparison with an implementation which only employs an SPM, performance improvements of up to 1.7× and 1.4× are observed through actual implementation on two modern FPGA platforms. These performance improvements are more pronounced for image sequences exhibiting greater inter-frame movements. In addition, reductions of on-chip memory resources by up to 3.2× are achievable using this framework. These results indicate that, on custom hardware platforms, there is substantial scope for improvement in the capture of data re-use when memory accesses are data dependent.

Macrophage recognition of polymers: effect of carboxylate groups

The effect of anionic carboxylate groups in copolymers of 2-hydroxyethyl methacrylate with sodium methacrylate on the adsorption of albumin, adhesion, spreading and fusion of macrophages has been demonstrated. The results show an inhibitory effect of increasing concentration of carboxylate groups of polymers on all studied parameters.     

治理深圳河第四期工程——可持续发展兼生态友好型新措施

深圳河是香港特别行政区和深圳经济特区之间的界河。为解决深圳河的防洪排涝问题,深圳市治理深圳河办公室和香港特别行政区政府渠务署致力于找出可持续发展的方法,以拓宽河道,治理水浸问题。本项目综合运用了最先进的一维、二维数学模型以及实体模型模拟泄洪设计,包括进水口溢流堰系统、出水口水闸和一个80 000 m3的开放式滞洪区。滞洪区的设计运用可持续发展理念,巧妙的湿地设计能够预防水土流失,支持生态发展,优化了泄洪方案。研究成果可为河道治理工程提供参考。     

Finding email correspondents in online social networks

Email correspondents play an important role in many people’s social networks. Finding email correspondents in social networks accurately, though may seem to be straightforward at a first glance, is challenging. Most of the existing online social networking sites recommend possible matches by comparing the information of email accounts and social network profiles, such as display names and email addresses. However, as shown empirically in this paper, such methods may not be effective in practice. To the best of our knowledge, this problem has not been carefully and thoroughly addressed in research. In this paper, we systematically investigate the problem and develop a practical data mining approach. We find that using only the profiles or the graph structures is far from effective. Our method utilizes the similarity between email accounts and social network user profiles, and at the same time explores the similarity between the email communication network and the social network under investigation. We demonstrate the effectiveness of our method using two real data sets on emails and Facebook.     

Polymerization of isobutylene initiated with the system 2,5-dichloro-2,5-dimethylhexane/SnCl4

Summary The polymerizations of isobutylene in dichloromethane at-20°C initiated with the system 2,5-dichloro-2,5-dimethylhexane (DDH)/SnCl₄ were investigated. The polyisobutylene (PIB) samples obtained were examined by GPC and their molecular weight distribution curves were determined. It was found that PIB products obtained by the conventional procedure have a bimodal MWD and the weight content of the lower-molecular weight fraction increases with increasing concentration of DDH in the polymerization feed. The effect of ageing of DDH/SnCl₄ mixtures prepared in advance on MWD of the PIB samples was also proved. The results achieved lead to a conclusion that the ageing of the initiation system consists probably in the formation of the complex DDH-SnCl₄-H₂O, which protogenically again initiates the oligomerization of isobutylene, giving rise to oils with a narrow MWD, the polydispersity index . The possible role of the coordination polymerization mechanism is discussed.