In Situ Growth of Superconducting Yba2Cu3O7-xThin Films

Using single-target on-axis sputter deposition, Y Ba₂Cu₃O_7-x films, with flatness oriented in the c axis and a zero-resistance temperature ( Tco ) of 89 K, were prepared by an in situ growth technique. This work examines the effect of the growth temperature on the properties of in situ films. The experimental results show that high-quality YBa₂Cu₃O_7-x films can be obtained by controlling the substrate temperature in a range from 680^oto 690^oC. In addition, a new parallel-circuit model is proposed and a simulation of the resistance versus temperature curve is presented.     

氧化铝粒体在κ-至α-相变过程的发育现象

本研究观察以三水铝矿石[(Gibbsite,Al(OH)3)]为原料获得之氧化铝微粒在κ-至α-相变过程中之粒体成长行为.相变过程存在临界晶径与基础晶径现象.前者之大小对κ-与α-相均约为35nm,后者则为60 nm.由于所得α-Al2O3粒体存有原始粉末粒体的外型,因此如要由三水氧化铝获得奈米级(小于100 nm)α-Al2O3粉末,则于热处理前应将三水氧化铝先行细化.     

Performance analysis for voice/data integration on a finite-buffermobile system

Personal communication service (PCS) networks offer mobile users diverse telecommunication applications, such as voice, data, and image, with different bandwidth and quality-of-service (QoS) requirements. This paper proposes an analytical model to investigate the performance of an integrated voice/data mobile network with finite data buffer in terms of voice-call blocking probability, data loss probability, and mean data delay. The model is based on the movable-boundary scheme that dynamically adjusts the number of channels for voice and data traffic. With the movable-boundary scheme, the bandwidth can be utilized efficiently while satisfying the QoS requirements for voice and data traffic. Using our model, the impact of hot-spot traffic in the heterogeneous PCS networks, in which the parameters (e.g., number of channels, voice, and data arrival rates) of cells can be varied, can be effectively analyzed. In addition, an iterative algorithm based on our model is proposed to determine the handoff traffic, which computes the system performance in polynomial-bounded time. The analytical model is validated by simulation     

Post-transplant changes of segment 4 after living related liver transplantation

Cocaine-induced thrombosis has been reported in the literature; however, its mechanism is not fully understood. Most cases are of small caliber vessels, such as the coronaries and cerebral vasculature. We report a case of a 36-year-old man with signs and symptoms of acute arterial insufficiency in his right lower extremity. At angiography, the right common iliac artery and the popliteal artery were occluded. The patient was successfully treated with thrombolytic therapy. Cocaine-induced thrombosis should be suspected in a patient with history of cocaine abuse who presents with acute arterial insufficiency in an extremity, without an identifiable source.     

基于原子构件的工作流建模方法

基于原子构件的工作流建模方法旨在从在本质上描述工作流过程模型的特征,动态构建工作流过程模型,实现模型的柔性、可重用性.通过分析工作流模型的特征,将工作流过程模型的构建分为3个层次,底层以原子构件及构件模型为基础,中间层建立元-元模型,上层以动态构建机制完成过程模型合成.该方法使得过程模型在构建时和运行时可以根据业务流程的变化自动的扩展、更新、重组,从而使得工作流过程模型具有柔性、可重用性和一定的智能性.     

消防车道最小转弯半径以及通道宽度的计算

该文根据车辆行驶稳定性因素以及车辆转向特性因素分析消防车道最小转弯半径以及通道宽度的设置。     

A software architecture for GPRS session management

General packet radio service (GPRS) provides efficient access to the integrated services Internet from wireless networks. When the GPRS‐attached mobile station attempts to send or receive data, a packet data protocol (PDP) context shall be established. The GPRS session management (SM) supports the PDP context handling, which consists of PDP context activation, deactivation, and modification procedures. In this paper, we propose an SM software architecture for the serving GPRS support node. Our design goals are to achieve compatibility, modularity, and flexibility. More importantly, our approach can accommodate the design of the SM software architecture for third‐generation wireless networks. Copyright © 2001 John Wiley & Sons, Ltd.     

Determining the optimal buffer size for short message transfer in a heterogeneous GPRS/UMTS network

Multimedia messaging service (MMS) enables the transmission of messages with full content versatility between mobile devices and from applications to these devices, which can be used over the general packet radio service (GPRS)/universal mobile telecommunications system (UMTS) short message service (SMS) network. In the GPRS/UMTS SMS network, the serving GPRS support node (SGSN) stores the mobile-terminated message in a queue until it is successfully transferred to the mobile device or its maximum waiting time expires. If the mobile device moves from one SGSN area to another before the waiting time has expired, the queued message is forwarded to the new SGSN and is immediately removed from the waiting queue of the old SGSN. Taking the forwarding and the expiration effects of queued messages into account, the paper develops an analytical model to study the system performance of a heterogeneous GPRS/UMTS SMS network, in which the parameters (e.g., message arrival rate, SGSN area residence time, buffer size, etc.) of SGSNs can be varied. On the basis of the analytical model, an iterative method is proposed to determine the optimal buffer size so that the available bandwidth is fully utilized and the message loss probability is minimized.     

Electrophoretic deposition and its use to synthesize ZrO2/Al2O3 micro-laminate ceramic/ceramic composites

Electrophoretic deposition has been employed to synthesize yttria-stabilized zirconia (YSZ)/alumina, laminar microcomposites with a total of 80 layers, >2mm. 10 wt% solids, ethanol suspensions of YSZ or Al₂O₃ powders were deposited layer by layer. The deposited samples had a green density, ~60% theoretical. The deposition process was characterized by the rate-of-deposition as a function of voltage and the microstructure of the sintered, theoretically dense samples was characterized by optical and electron microscopy. Microindentation was used to explore the mechanical properties of the laminates.