Orthogonal drawings and crossing numbers of the Kronecker product of two cycles

An orthogonal drawing of a graph is an embedding of the graph in the plane such that each edge is representable as a chain of alternately horizontal and vertical line segments. This style of drawing finds applications in areas such as optoelectronic systems, information visualization and VLSI circuits. We present orthogonal drawings of the Kronecker product of two cycles around vertex partitions of the graph into grids. In the process, we derive upper bounds on the crossing number of the graph. The resulting upper bounds are within a constant multiple of the lower bounds. Unlike the Cartesian product that is amenable to an inductive treatment, the Kronecker product entails a case-to-case analysis since the results depend heavily on the parameters corresponding to the lengths of the two cycles.     

一种基于市场机制的数据网格复制选择策略*

针对数据网格提出了一种基于市场机制的复制选择策略,以一般均衡理论为基础,依靠市场机制实现数据网格的复制选择策略。首先给出了数据网格复制选择的市场模型,其中效用函数用于刻画应用代理与数据所在站点之间进行数据传输的消耗;然后在此基础上根据供需规律提出了副本的自动生成策略以及副本的自动选择策略;最后对本策略对应的算法时间复杂度和空间复杂度进行了分析。     

Static and Dynamic Data Models for the Storage Resource Manager v2.2

We present a conceptual model for the Storage Resource Manager, the standard interface adopted for the storage systems of the Worldwide Large Hadron Collider Computing Grid. This model provides a clear and concise definition of the structural and behavioral concepts underlying the interface specification and is meant to support service and application development. Different languages (natural language, UML diagrams, and simple set-theoretic and logical notation) are used to describe different aspects of the model.     

Grid enabled magnetic resonance scanners for near real-time medical image processing

This paper presents the initial steps taken to integrate the University of California at San Francisco Radiology Department's magnetic resonance (MR) scanners with its high-performance computing (HPC) grid. The objective is to improve patient care by enabling near real-time, computationally intensive medical image processing, directly at an MR scanner. A graphical software tool is described that was developed to run on the MR scanners for submitting processing jobs to the Departmental grid. The computationally intensive parallel reconstruction and quantification of large, multi-dimensional MR spectroscopic imaging (MRSI) data sets was used as the prototype application for this system. Initial results indicate that real-time processing of medical imaging data on a shared HPC resource is reliable and possible in a clinically acceptable time of less than 5 min. The Department's HPC resource is comprised of hardware owned by multiple research groups at three separate University facilities throughout San Francisco.     

Trusted Grid Computing with Security Binding and Trust Integration

Trusted Grid computing demands robust resource allocation with security assurance at all resource sites. Large-scale Grid applications are being hindered by lack of security assurance from remote resource sites. We developed a security-binding scheme through site reputation assessment and trust integration across Grid sites. We do not treat the trust factor deterministically. Instead, we apply fuzzy theory to handle the fuzziness or uncertainties behind all trust attributes. The binding is achieved by periodic exchange of site security information and matchmaking to satisfy user job demands. PKI-based trust model supports Grids in multi-site authentication and single sign-on operations. However, cross certificates are inadequate to assess local security conditions at Grid sites. We propose a new fuzzy-logic trust model for distributed trust aggregation through fuzzification and integration of security attributes. We introduce the trust index of a Grid site, which is determined by site reputation from its track record and self-defense capability attributed to the risk conditions and hardware and software defenses deployed at a Grid site. A Secure Grid Outsourcing (SeGO) system is designed for secure scheduling a large number of autonomous and indivisible jobs to Grid sites. Significant performance gains are observed after trust aggregation, which is evaluated by running scalable NAS and PSA workloads over simulated Grids. Our security-binding scheme scales well with increasing user jobs and Grid sites. The new scheme can guide the security upgrade of Grid sites and predict the Grid performance of large workloads under risky conditions. The research work reported here was supported by a NSF ITR Grant 0325409. The paper is significantly extended from preliminary results presented in IFIP International Conference on Network and Parallel Computing (NPC-2004), IEEE International Parallel and Distributed Processing Symposium (IPDPS-2005), and International Workshop on Grid Security and Resource Management (GSRM-2005). The corresponding author is Kai Hwang at the University of Southern California.     

Synthesis of high-density MgO films by a novel magnetron sputtering system

A novel magnetron sputtering system, which included simply designed two grids between target and substrate, was developed in our laboratory for the synthesis of high-density MgO films. In order to investigate the effect of grids assisted magnetron sputtering, MgO films were deposited by conventional magnetron, one grid assisted magnetron and two grids assisted magnetron. The saturated ion current density and Mg ion fraction in MgO discharges generated by grids assisted magnetron were increased in comparison with those obtained in conventional magnetron, which means that grids assisted magnetron led to the enhancement of plasma density. As a result of microstructure analysis, grids assisted magnetron produced a higher density MgO film with smoother surface compared to that obtained in conventional magnetron.     

东北电网利用特高压输电的可行性及引入时机分析

针对东北电网发电机和发电厂的规模经济性,燃料、运输成本和发电能源的可用性,网损和短路电流水平,生态环境等因素,分析东北电网发展特高压输电需求和技术可行性、东北特高压输电方向和受端市场空间,认为东北电网利用特高压输电是可行的,且在“十二五”期间引入较为合适。     

基于网格法的等值线绘制方法

等值线是一种形和数的统一。在许多领域是成果数据表示的重要图件之一。时工程应用中的等值线图的绘制方法进行了研究，常规的等值线绘制方法分为矩形网格法和不规则三角形网法2种，矩形网格法具有算法简单的优点。其绘制的步骤一般为：离散数据网格化、网格点数值化、等值点的计算、等值线的追踪、光滑和标记等值线。详细阐述了采用矩形网格法绘制的步骤及其计算机实现。采用Delphi开发了运用该法绘制等值线的软件，可应用于不同的操作平台，移植性好。     

Unibus: a contrarian approach to grid computing

Despite maturing in many ways, heterogeneous distributed computing platforms continue to require substantial effort in terms of software installation and management for efficient use, often necessitating manual intervention by resource providers and end-users. In this paper we propose a novel model of resource sharing that is a viable alternative to that commonly adopted in the grid community. Our model, termed Unibus, shifts the resource virtualization and aggregation responsibilities to the software at the client side, taking these burdens away from resource providers. Drawing from parallels with operating systems, we argue that distributed resources may be unified and aggregated at the user’s end, in a manner similar to ordinary peripheral devices. Running on the user’s access device, the overlay system software can virtualize remote resources via dynamically deployed software mediators analogous to device drivers, reconfiguring the resources if necessary via “firmware” modules. To illustrate the feasibility of the Unibus model, we have prototyped a development toolkit automating the installation, build, run, and post-processing stages of MPI applications. Through the provided console, this toolkit can deploy and configure an MPI execution environment across a set of heterogeneous, isolated distributed resources, turning them into a coherent virtual machine with a single interface point. We conducted a series of experiments with the NAS Parallel Benchmarks. Results indicate that the toolkit preserves the application performance of “bare” MPI, while substantially reducing maintenance and configuration efforts. Overall, the results suggest that the envisioned client side overlay model for resource sharing may potentially be able to address some of long-standing obstacles in building heterogeneous HPC systems.

计算风工程中的网格技术对比研究

通过对比风工程数值模拟中可供选择的各种网格技术,深入分析了几种网格各自的特点。结构网格与非结构网格的优缺点基本是对立互补的,混合网格技术代表了当前和未来网格技术的主要发展趋势。自适应笛卡尔网格自动化程度高,对于各向同性流动问题极具优势。由于目前从事计算风工程的专业人员网格生成能力较差,自适应笛卡尔网格特别适合于风工程的低速复杂湍流问题的模拟。