A self-aligned gate III-V heterostructure FET process forultrahigh-speed digital and mixed analog/digital LSI/VLSI circuits

A planar ion-implanted self-aligned gate process for the fabrication of high-speed digital and mixed analog/digital LSI/VLSI integrated circuits is reported. A 4-b analog-to-digital converter, a 2500-gate 8×8 multiplier/accumulator, and a 4500-gate 16×16 complex multiplier have been demonstrated using enhancement-mode n⁺ -(Al,Ga)As/MODFETs, superlattice MODFETs, and doped channel heterostructure field-effect transistors (FETs) whose epitaxial layers were grown by molecular-beam epitaxy. With nominal 1-μm gate-length devices, direct-coupled FET logic ring oscillators with realistic circuit structures have propagation delays of 30 ps/stage at a power dissipation of 1.2 mW/stage. In LSI circuit operation, these gates have delays of 89 ps/gate at a power dissipation of 1.38 mW/gate when loaded with an average fan-out of 2.5 gates and about 1000 μm of high-density interconnects. High-performance voltage comparator circuits operated at sampling rates greater than 2.5 GHz at Nyquist analog input rates and with static hysteresis of less than 1 mV at room temperature. Fully functional 4-b analog-to-digital circuits operating at frequencies up to 2 GHz were obtained     

Effect of mild acid treatment on the survival, enteropathogenicity, and protein production in vibrio parahaemolyticus

Vibrio parahaemolyticus is an important food-borne enteropathogen that encounters various adverse conditions in its native environment or during infection. Effects of mild acid treatment on survival under stress conditions, enteropathogenicity, and protein production in this pathogen were investigated. Logarithmically grown cells, at pH 7.5 shifted to pH 5.0 for 30 min, were more resistant to subsequent acid challenge at pH 4.4. A two-phase adaptive procedure (pH 5.8 for 30 min; pH 5.0 for 30 min) was better than a single-phase procedure for enhancing the acid tolerance of this pathogen. The acid-adapted cells were cross-protected against the challenges of low salinity and thermal inactivation. One-dimensional polyacrylamide gel electrophoresis revealed that proteins with molecular masses of 6.4, 9.0, 13.6, 16.3, 18.9, 22.9, 24.4, 28.3, 33. 9, 36.9, 41.2, 47.6, 58.1, 65.6, 80.5, 88.2, and 96.9 kDa were induced or significantly enhanced, while proteins of 25.3, 30.1, 30. 7, and 91.7 kDa were significantly inhibited. Two-dimensional polyacrylamide gel electrophoresis revealed that 20 species of proteins were induced or significantly enhanced, while 26 species were inhibited. In assays conducted using the suckling mouse model, enteropathogenicity of the acid-adapted cells was significantly enhanced in terms of intestine/body weight ratio and in vivo recovery of infected cells.     

Autonomic nervous activity at episodes of myocardial ischemia in patients with coronary artery disease by heart rate power spectral analysis

Heart rate power spectral analysis in 44 patients with coronary artery disease was obtained from 24-hour dynamic electrocardiogram. 195 episodes of transient myocardial ischemia that was defined as horizontal or down sloping depression of the ST segment of > or = 0.1 mV and lasted for > or = 2 minutes were studied. The area of low frequency components (LF, 0.02-0.10 Hz) representing predominontly sympathetic tone with some contribution from the parasympathetic tone and that of high frequency components (HF, 0.15-0.40 Hz) representing mainly parasympathetic tone and the value of LF/HF on 4 minute heart rate power spectral graph at the deepest depression of ST segment were compared with that before the episode of myocardial ischemia. The area of HF of fast rate myocardial ischemia occurring in night reduces significantly (P < 0.001), the value of LF/HF increases markedly (P < 0.05) and the area of LF increases slightly. The results suggest that there is a change of autonomic nervous activity during the episode of fast rate myocardial ischemia in night, parasympathetic nervous tone decreases markedly, there may be secondary increase of sympathetic nervous activity.     

Diagnosis and treatment of iatrogenic ureteral injury

Diagnosis and treatment of 17 patients who sustained 20 iatrogenic ureteral injuries were analyzed. Primary operations in which ureteral injury occurred are almost gynecologic procedures and general surgery. Injuries were managed by ureteroureterostomy in four, ureteral stent in one, removal suture ligation and ureteral double J-catheter in one, ureteroneocystostomy in ten, psoas-hitch technique and ureteroneocystostomy in one, nephrectomy in two. All patients with appropriate repair were followed-up periods of three to five years. Renal function of these patients had optimal results. When ureteral injury occurs, B-US, IVU, cystoscopy, retrograde ureterography or infusion of dye may be useful. An appropriate repair should be chosen according to length and position of ureteral injuries. Reoperation was optimal in two to three weeks. Immediate recognition of accidental ureteral injury provides optimal results. Patients with unrecognized injuries had suboptimal results.     

Ohmic contact and transport properties of II–VI Green/Blue laser diodes

The employment of the Zn(Se,Te) pseudo-graded contacting scheme to p-type ZnSe-based alloys contributes directly to the recent demonstration of room temperature continuous-wave operation of II– VI green-blue laser diodes. Contact ohmicity is maintained down to cryogenic temperatures which enabled the investigation of electrical transport properties associated with the p-type nitrogen-doped ZnSe, Zn(S,Se), and (Zn,Mg)(S,Se). The observation of both persistent photoconductivity and a metastable population of holes which are in thermodynamic equilibrium with hydrogenic acceptors having reduced activation energy suggests the presence of a DX-like behavior for holes in p-type (Zn,Mg)(S,Se).     

基于MPC850 VxWorks系统的BSP设计

首先介绍嵌入式系统VxWorks及其启动过程;分析了基于MPC 850最小系统的硬件和BSP的执行流程;重点研究了MPC850BSP的设计与应用程序加载,包括其硬件驱动程序的设计、应用程序加载、建立调试环境和target server的配置等;基于MPC850系统的Vxworks BSP调试平台的实现,对Vxworks上层应用软件和底层硬件驱动的并行开发有着很重要的意义。     

折线链节点标注技术

针对传统多边形位置关系计算比较烦琐,以及简单多边形的理论难以拓展到一般多边形的问题,提出标注节点状态的方法.通过定义11种位置来描述折线链上每个节点的状态,再采用"线段端点与线段"和"线段端点与邻折线"的标注方法来实现任意折线链的标注,同时利用两线段分割预处理使相交仅发生在端点处,从而使算法更高效;然后给出折线链基本位置关系的节点特征,并且探讨了三维顶点的标注方法.该方法的标注原理简单、方法实用,算法空间和时间复杂度分别为O(n)和O(n2).实验结果表明,该方法对任意形状的折线链都能实现稳定标注;通过搜索节点状态特征可以求解折线链间的相互关系,还可以实现一般折线链的碰撞检测、相交区域计算以及多边形简单化分解等.     

一种新的SAR图像斜距多普勒定位模型的直接解法

斜距多普勒定位模型是实现SAR图像无控制点定位的基本模型,因此如何高效准确地获得RD方程组的解成为实现SAR图像无控制点几何定位的根本问题,也是实现SAR自动图像定位的关键。首先利用地固坐标系下目标速度为零的特性,简化RD模型并整理为一元四次方程,然后利用一元四次方程求根方法,推导出斜距多普勒定位模型的明确数学解析解,并与常用的数值迭代求解方法进行比较分析,仿真结果验证了推导的正确性。新解法具有无需设置初始值,易于编程实现,鲁棒性高的特点。     

项目实训中的协同编程方法研究

在高职院校的软件项目实训环节中,大多项目需要团体协作进行编程。针对如果有效提高学生的协同编程效率、团队合作意识以及合作学习能力的问题,提出了基于Dillenbourg原则的协同编程方法。通过实践证明,该方法取得了良好的实训效果。     

Layout Optimization for Greenhouse WSN Based on Path Loss Analysis

When wireless sensor networks (WSN) are deployed in the vegetable greenhouse with dynamic connectivity and interference environment, it is necessary to increase the node transmit power to ensure the communication quality, which leads to serious network interference. To offset the negative impact, the transmit power of other nodes must also be increased. The result is that the network becomes worse and worse, and node energy is wasted a lot. Taking into account the irregular connection range in the cucumber greenhouse WSN, we measured the transmission characteristics of wireless signals under the 2.4 Ghz operating frequency. For improving network layout in the greenhouse, a semi-empirical prediction model of signal loss is then studied based on the measured data. Compared with other models, the average relative error of this semi-empirical signal loss model is only 2.3%. Finally, by combining the improved network topology algorithm and tabu search, this paper studies a greenhouse WSN layout that can reduce path loss, save energy, and ensure communication quality. Given the limitation of node-degree constraint in traditional network layout algorithms, the improved algorithm applies the forwarding constraint to balance network energy consumption and constructs asymmetric network communication links. Experimental results show that this research can realize the energy consumption optimization of WSN layout in the greenhouse.