Efficient support for interactive service in multi-resolution VOD systems

Advances in high-speed networks and multimedia technologies have made it feasible to provide video-on-demand (VOD) services to users. However, it is still a challenging task to design a cost-effective VOD system that can support a large number of clients (who may have different quality of service (QoS) requirements) and, at the same time, provide different types of VCR functionalities. Although it has been recognized that VCR operations are important functionalities in providing VOD service, techniques proposed in the past for providing VCR operations may require additional system resources, such as extra disk I/O, additional buffer space, as well as network bandwidth. In this paper, we consider the design of a VOD storage server that has the following features: (1) provision of different levels of display resolutions to users who have different QoS requirements, (2) provision of different types of VCR functionalities, such as fast forward and rewind, without imposing additional demand on the system buffer space, I/O bandwidth, and network bandwidth, and (3) guarantees of the load-balancing property across all disks during normal and VCR display periods. The above-mentioned features are especially important because they simplify the design of the buffer space, I/O, and network resource allocation policies of the VOD storage system. The load-balancing property also ensures that no single disk will be the bottleneck of the system. In this paper, we propose data block placement, admission control, and I/O-scheduling algorithms, as well as determine the corresponding buffer space requirements of the proposed VOD storage system. We show that the proposed VOD system can provide VCR and multi-resolution services to the viewing clients and at the same time maintain the load-balancing property. Received June 9, 1998 / Accepted April 26, 1999     

Eutectic cell wall morphology and tensile embrittlement in ferritic spheroidal graphite cast iron

Four ferritic spheroidal graphite (SG) cast irons (3.4C-3.9Si, 3.5C-2.7Si, 3.5C-2.0Si, and 2.0C-2.1Si, in wt pct) were chosen to study the eutectic cell morphology and the related tensile embrittlement. For the three test materials with high carbon concentration, the results indicate that the average eutectic cell wall size and the amount of cell wall inclusions decrease with decreasing silicon concentration. Compared to the test material with 3.5C-2.0Si, which has many inclusions dispersed in the ferrite matrix, the one with 2.0C-2.1Si shows larger average eutectic cell wall size and larger degree of inclusion clustering in the cell walls. Tensile embrittlement may occur in two temperature ranges, namely, the intermediate low-temperature range at the end of the upper elongation shelf and the intermediate high-temperature range of around 400 °C. In both cases, the brittle cracks are initiated preferentially at the inclusion clusters in the eutectic cell wall region. Hence, the two tensile embrittlements occur only for the materials with a larger degree of inclusion clustering in the eutectic cell walls.     

Effects of cooling rate and annealing treatment on sensitization of austenitic-ferritic duplex stainless steel

Duplex stainless steel has higher corrosion resistance and better mechanical properties than conventional type 300 series stainless steel. The corrosion behavior of duplex stainless steel is strongly dependent on the ratio, shape, size and distribution of austenite and ferrite phase in the microstructure. The relationship between the microstructure and the corrosion behavior of the duplex stainless steel was studied. For this purpose, the duplex stainless steel samples were solution heal treated at 1150°C followed by either cooling at various rates (water quenching, air coooling, furnace colling with door opened and door closed) to 820°C and then water quenching to room temperature, or quenching to room temperature and annealing heat treatment at 840°C for various lengths of time. A double loop electrochemical polentiodynamic reactivation (EPR) test was carried out to examine the effect of various cooling procedures or annealing treatment on the sensitization of duplex stainless steel. The grain size, shape, and distribution of the two phases were examined under microscope. From the test results, the relationships were discussed among heat treatment, electrochemical properties and microstructure.     

具有接头系统的冲击凿入效率研究

本文运用波动力学对具有接头系统的冲击凿入效率进行了理论分析,给出了具有接头的冲击凿入系统传递函数Ｈ＿（ＪＰ）（Ｓ）＝Ｈ＿ｊ（Ｓ）·Ｈ＿ｐ（Ｓ）［此外Ｈ＿Ｊ（ｓ）为接头传递函数,Ｈ＿Ｐ（Ｓ）为凿入传递函数］,实际计算了刚性和等截面活塞两种具有接头凿入系统的能量传递效率,并分析了凿入系统各参数对能量传量传递效率的影响。     

Radiative Ignition of Pyrotechnics: Effect of Wavelength on Ignition Threshold

Using a broadband Xenon lamp and a high power laser diode, the ignition of several pyrotechnic compositions was evaluated using ultraviolet(UV), visible and infrared(IR) radiation. At irradiance levels of 4.9 W/cm² none of the compositions were ignited using UV radiation but SR112, B/Fe₂O₃ and gunpowder showed reactions to visible radiation at irradiance levels as low as 8.1 W/cm². Most of the compositions were ignited with IR radiation but Mg/NaNO₃ and SR 112 could not be ignited at irradiance levels of up to 300 W/cm². It is proposed that the difference in the response of the compositions was not directly related to the radiation absorption characteristics of the compositions; but was dependant on many physical, chemical and optical characteristics of the pyrotechnic powders. Increasing the irradiance reduces the time to ignition for most compositions.     

上海建设大事记

△1月1日,上海市2004年重大工程建设完成投资655亿元。年内开工和建成的项目超过和达到年初的计划目标,分别为12项和16项。其中,以“三港两网”为骨架的现代化基础设施,如上海国际航运中心洋山深水港一期工程港区陆域已按期形成,5个集装箱泊位基本建成,大桥下部结构全面完成;长江隧桥工程、浦东铁路都已开工建设;轨道交通网和高速公路网运营里程分别达到125km(含磁浮)、375km;中环线北段部分道路于2005年春节前实现通车;新型产业体系建设取得重大进展,如宝钢一钢不锈钢及碳钢热轧板卷一期项目建成投产,使不锈钢生产不再依赖进口;上海化工区…     

上海建设大事记(2005年5～6月份)

△5月3日,宝钢集团今年安排的宝钢宽厚板轧机及配套连铸工程项目,计划总投资67.98亿元,今年投资计划9.06亿元,已完成3.82亿元;宝钢1 800 mm冷轧带钢工程项目,计划总投资73.69亿元,今年计划投资6.30亿元,已完成1.00亿元,宝钢一钢不锈钢扩建工程项目,计划总投资39.50亿元,今年计划投     

某铝合金汽车发动机罩外板冲压成形工艺

针对铝合金材料弹性模量小、在室温条件下的冲压成形性能较差的问题,以铝合金汽车发动机罩外板为例,基于Autoform软件平台分析其冲压成形过程,通过优化型面结构改进零件的成形质量,研究了冲压工艺参数对零件减薄率和回弹的影响规律。结果表明:当采用小的压边力时,板料的减薄较小;在一定范围内,随着压边力的增大,零件的回弹有所减小。最终通过对模具进行型面补偿并结合适当的工艺参数调整,有效地减小了零件回弹。基于结果进行了发动机罩外板的冲压试验,通过模具调试使制件达到生产要求。     

广西“三线一单”生态环境分区管控成果落地应用实践

随着全国“三线一单”生态环境分区管控体系基本建立，推动成果在基层落地应用是影响社会和经济高质量发展的重要抓手。文章阐述了广西“三线一单”管控分区成果的核心内容，首次系统探究成果在支撑区域重大战略实施、指导产业园区规划布局和园区环保基础设施建设优化、支撑广西矿产资源总体规划环境影响评价、推进超标环境管控单元治理等方面的应用实践，从立法和制度建设、动态更新调整、跟踪评估考核、基层应用4个方面分析了成果落地应用存在的问题，并提出相关建议。本研究成功打造了广西“三线一单”成果落地应用“样板”，助力提升生态环境治理体系和治理能力现代化，为各地推动生态环境分区管控全面落地应用提供了借鉴。     

Facial optical flow estimation via neural non-rigid registration

Computational Visual Media - Optical flow estimation in human facial video, which provides 2D correspondences between adjacent frames, is a fundamental pre-processing step for many applications,...