Efficient binary to quaternary and vice versa converters: embedding in quaternary arithmetic circuits

The Journal of Supercomputing - Reversible logic is a nowadays promising choice for circuit design technologies since it is having diversified applications in the fields of digital signal...     

Transformation of XML data using updates without side effects

One of the key technologies of XML data management is XQuery, the query language for both retrieving and transforming XML data. In the paper, limitations of the XQuery facilities for transforming XML data are discussed. It is shown that, for one important class of queries, XQuery expressions are too cumbersome and computationally inefficient. In the paper, it is suggested to extend the XQuery language by functional update expressions. From the syntax standpoint, such expressions are similar to expressions of XML update languages. However, they can be evaluated without side effects, which makes it possible to integrate them in XQuery in a natural way. The expressiveness of the extended language is demonstrated, and approaches to efficient implementation of the suggested extension are considered. In addition, the problem of arbitrary compositions of XML query and update expressions (the problem of nested update expressions) is discussed. The existing XML update languages are based, as a rule, on the XQuery language; however, the possibility of constructing arbitrary compositions of XQuery expressions and those of the XML update language is not provided. This impedes development of practical XML applications in the XQuery language. In the paper, an approach to solving the composition problem based on the use of functional update expressions is suggested. Possibilities of the implementation of the suggested extension are discussed.     

Efficient processing of streaming updates with archived master data in near-real-time data warehousing

In order to make timely and effective decisions, businesses need the latest information from data warehouse repositories. To keep these repositories up-to-date with respect to end user updates, near-real-time data integration is required. An important phase in near-real-time data integration is data transformation where the stream of updates is joined with disk-based master data. The stream-based algorithm MESHJOIN (Mesh Join) has been proposed to amortize disk access over fast streams. MESHJOIN makes no assumptions about the data distribution. In real-world applications, however, skewed distributions can be found, such as a stream of products sold, where certain products are sold more frequently than the remainder of the products. The question arises is how much does MESHJOIN lose in terms of performance by not adapting to data skew. In this paper we perform a rigorous experimental study analyzing the possible performance improvements while considering typical data distributions. For this purpose we design an algorithm Extended Hybrid Join (X-HYBRIDJOIN) that is complementary to MESHJOIN in that it can adapt to data skew and stores parts of the master data in memory permanently, reducing the disk access overhead significantly. We compare the performance of X-HYBRIDJOIN against the performance of MESHJOIN. We take several precautions to make sure the comparison is adequate and focuses on the utilization of data skew. The experiments show that considering data skew offers substantial room for performance gains that cannot be found in non-adaptive approaches such as MESHJOIN. We also present a cost model for X-HYBRIDJOIN, and based on that cost model, the algorithm is tuned.     

Efficient computation of distance labeling for decremental updates in large dynamic graphs

Since today’s real-world graphs, such as social network graphs, are evolving all the time, it is of great importance to perform graph computations and analysis in these dynamic graphs. Due to the fact that many applications such as social network link analysis with the existence of inactive users need to handle failed links or nodes, decremental computation and maintenance for graphs is considered a challenging problem. Shortest path computation is one of the most fundamental operations for managing and analyzing large graphs. A number of indexing methods have been proposed to answer distance queries in static graphs. Unfortunately, there is little work on answering such queries for dynamic graphs. In this paper, we focus on the problem of computing the shortest path distance in dynamic graphs, particularly on decremental updates (i.e., edge deletions). We propose maintenance algorithms based on distance labeling, which can handle decremental updates efficiently. By exploiting properties of distance labeling in original graphs, we are able to efficiently maintain distance labeling for new graphs. We experimentally evaluate our algorithms using eleven real-world large graphs and confirm the effectiveness and efficiency of our approach. More specifically, our method can speed up index re-computation by up to an order of magnitude compared with the state-of-the-art method, Pruned Landmark Labeling (PLL).     

EXEM: Efficient XML data exchange management for mobile applications

In the past decade, the number of mobile devices has increased significantly. These devices are in turn showing more computational capabilities. It is therefore possible to envision a near future where client applications may be deployed on these devices. There are, however, constraints that hinder this deployment, especially the limited communication bandwidth and storage space available. This paper describes the Efficient XML Data Exchange Manager (EXEM) that combines context-dependent lossy and lossless compression mechanisms used to support lightweight exchange of objects in XML format between server and client applications. The lossy compression mechanism reduces the size of XML messages by using known information about the application. The lossless compression mechanism decouples data and metadata (compression dictionary) content. We illustrate the use of EXEM with a prototype implementation of the lossless compression mechanism that shows the optimization of the available resources on the server and the mobile client. These experimental results demonstrate the efficiency of the EXEM approach for XML data exchange in the context of mobile application development.

Efficient and retargetable SIMD translation in a dynamic binary translator

The single‐instruction multiple‐data (SIMD) computing capability of modern processors is continually improved to deliver ever better performance and power efficiency. For example, Intel has increased SIMD register lengths from 128 bits in streaming SIMD extension to 512 bits in AVX‐512. The ARM scalable vector extension supports SIMD register length up to 2048 bits and includes predicated instructions. However, SIMD instruction translation in dynamic binary translation has not received similar attention. For example, the widely used QEMU emulates guest SIMD instructions with a sequence of scalar instructions, even when the host machines have relevant SIMD instructions. This leaves significant potential for performance enhancement. We propose a newly designed SIMD translation framework for dynamic binary translation, which takes advantage of the host's SIMD capabilities. The proposed framework has been built in HQEMU, an enhanced QEMU with a separate thread for applying LLVM optimizations. The current prototype supports ARMv7, ARMv8, and IA32 guests on the X86‐64 AVX‐2 host. Compared with the scalar‐translation version HQEMU, our framework runs up to 1.84 times faster on Standard Performance Evaluation Corporation 2006 CFP benchmarks and up to 6.81 times faster on selected real applications.     

Efficient processing of top-k twig queries over probabilistic XML data

The flexibility of XML data model allows a more natural representation of uncertain data compared with the relational model. Matching twig pattern against XML data is a fundamental problem in querying information from XML documents. For a probabilistic XML document, each twig answer has a probabilistic value because of the uncertainty of data. The twig answers that have small probabilistic value are useless to the users, and usually users only want to get the answers with the k largest probabilistic values. To this end, existing algorithms for ordinary XML documents cannot be directly applicable due to the need for handling probability distributional nodes and efficient calculation of top-k probabilities of answers in probabilistic XML. In this paper, we address the problem of finding twig answers with top-k probabilistic values against probabilistic XML documents directly. We propose a new encoding scheme called PEDewey for probabilistic XML in this paper. Based on this encoding scheme, we then design two algorithms for finding answers of top-k probabilities for twig queries. One is called ProTJFast, to process probabilistic XML data based on element streams in document order, and the other is called PTopKTwig, based on the element streams ordered by the path probability values. Experiments have been conducted to study the performance of these algorithms.     

Stringlish: improved English string searching in binary files

When analyzing binary files, printable strings are easy to find, but a naïve approach yields a large number of false positives: ‘uninteresting’ string‐like sequences that occur by chance in the binary. We present a lightweight yet surprisingly effective method of filtering printable strings for English or English‐like sequences. Copyright © 2015 John Wiley & Sons Ltd.     

Efficient XML data placement schemes over multiple mobile wireless broadcast channels

The Journal of Supercomputing - Broadcasting is one of the basic ways to access XML data via mobile wireless networks. In these networks, XML data are disseminated over a wireless broadcast channel...     

面向资源受限用户的高效动态数据审计方案

物联网(IoT)设备推动着云存储外包数据服务的快速发展,从而使云存储外包数据服务得到越来越多终端用户的青睐,因此如何确保云服务器中用户数据的完整性验证成为一个亟待解决的热点问题.针对资源受限的用户,目前的云数据审计方案存在运算复杂、开销高和效率低等问题.为了解决这些问题,提出一个面向资源受限用户的高效动态数据审计方案....     

An efficient XML encoding and labeling method for query processing and updating on dynamic XML data

In this paper, we propose an efficient encoding and labeling scheme for XML, called EXEL, which is a variant of the region labeling scheme using ordinal and insert-friendly bit strings. We devise a binary encoding method to generate the ordinal bit strings, and an algorithm to make a new bit string inserted between bit strings without any influences on the order of preexisting bit strings. These binary encoding method and bit string insertion algorithm are the bases of the efficient query processing and the complete avoidance of re-labeling for updates. We present query processing and update processing methods based on EXEL. In addition, the Stack-Tree-Desc algorithm is used for an efficient structural join, and the String B-tree indexing is utilized to improve the join performance. Finally, the experimental results show that EXEL enables complete avoidance of re-labeling for updates while providing fairly reasonable query processing performance.     

抽取XML文档到关系数据库

XML在关系数据库中的存储问题是XML研究领域中的一个重要问题。在总结多种映射方法的基础上,提出了一种方法将多个相似的XML文档进行解析,根据映射关系,生成各自的关系模式,并分析归纳出一个集成的关系模式,然后创建一个关系数据库,并在映射关系的基础上提取并存储XML文档数据到关系数据库。此方法以较为简洁的结构保存了XML文档的数据信息,其最大的特点就是不用考虑文档的模式信息（DTD,XML Schema）。并通过一个具体的实验结果来说明这种方法的有效性。     

调用XML中的Flash文件制作动态Flash课件相册

通过编写Flash的ActionScript脚本语言,实现在Flash中调用外部XML数据文件,而且这些XML数据文件都是由为实现同一个教学目标而制作的Flash课件,使用动态交互的加裁这一特性来制作动态Flash课件相册,并在制作过程中进行了初步的探讨,并取得了较好的效果,现就制作过程中会遇到的难题及解决方法进行详细的演示说明.     

OnceSAXParser：一种高效轻量的XML解析器

通过优化XML词法和语法处理以及构造轻量级体系结构，实现了支持SAX的高效XML解析器――OnceSAXParser。文中还将OnceSAXParser与目前最流行的XML解析器Xerces进行了对比分析和性能测试，结果显示OnceSAXParser的性能比Xerces平均提高了27%以上。     

Higher-order updates for dynamic responses in structural optimization

Problems of structural re-analyses in design optimization with constraints on the vibration response of dynamically loaded structures have been addressed. The inherent nonlinearity of the response quantities with respect to the design variables has in the past limited the application to first-order natural frequency updates. Second-order methods have tended to be prohibitive because of the need to evaluate the natural modes (eigenvectors) updates.The method proposed adopts an alternate and more direct approach to the forced vibration problems by evaluating the nodal response updates in a given direction. The update formulation developed takes advantage of the mutual orthogonality of the natural modes to construct higher-order directional derivatives of the transformed co-ordinate (modal) response quantities. These are subsequently used to obtain a total summation of the Taylor series representation for the response updates. The formulation is particularly suited to the design of large structures where modal truncation can be employed to restrict the computational costs. Numerical examples have been provided to illustrate both the higher quality and the effects of modal truncation on the results.