A unified critical state model for geomaterials with an application to tunnelling

This paper is prepared in honour of Professor E.T. Brown for his outstanding contributions to rock mechanics and geotechnical engineering and also for his personal influence on the first author's research career in geomechanics and geotechnical engineering. As a result, we have picked a topic that reflects two key research areas in which Professor E.T. Brown has made seminal contributions over a long and distinguished career. These two areas are concerned with the application of the critical state concept to modelling geomaterials and the analysis of underground excavation or tunnelling in geomaterials.Partially due to Professor Brown's influence, the first author has also been conducting research in these two areas over many years. In particular, this paper aims to describe briefly the development of a unified critical state model for geomaterials together with an application to cavity contraction problems and tunnelling in soils.     

A Dual Inhibitor of DYRK1A and GSK3β for β-Cell Proliferation: Aminopyrazine Derivative GNF4877

Loss of β-cell mass and function can lead to insufficient insulin levels and ultimately to hyperglycemia and diabetes mellitus. The mainstream treatment approach involves regulation of insulin levels; however, approaches intended to increase β-cell mass are less developed. Promoting β-cell proliferation with low-molecular-weight inhibitors of dual-specificity tyrosine-regulated kinase 1A (DYRK1A) offers the potential to treat diabetes with oral therapies by restoring β-cell mass, insulin content and glycemic control. GNF4877, a potent dual inhibitor of DYRK1A and glycogen synthase kinase 3β (GSK3β) was previously reported to induce primary human β-cell proliferation in vitro and in vivo. Herein, we describe the lead optimization that lead to the identification of GNF4877 from an aminopyrazine hit identified in a phenotypic high-throughput screening campaign measuring β-cell proliferation.     

3-三氟甲基-5,6,7,8-四氢-1,2,4-三唑[4,3-α]吡嗪盐酸盐的合成

乙二胺与氯乙酸乙酯经取代、环合反应制得2-哌嗪酮,2-哌嗪酮与Boc酸酐进行氨基保护反应后,再与五硫化二磷进行硫代反应制得4-(N-叔丁氧羰基)-2-哌嗪硫酮,其与三氟乙酰肼经取代、环合、脱叔丁氧羰基成盐,得标题化合物,总收率为45.7%(以氯乙酸乙酯计)。为磷酸西他列汀中间体的工业化生产提供了一条较理想的工艺路线。     

UML在网络安全监控系统建模中的应用

本文首先介绍了UML的特性,然后运用UML对网络安全监控系统中的数据采集系统进行了可视化的建模,建立了系统的需求模型和设计模型的各种视图,最后总结了用UML进行系统需求分析和设计的优越性.     

Study of Disk-Loaded Waveguide Filled with Plasma

Recently disk-loaded waveguide has been widely used in high-power traveling wave tubes (HPTWT). It has been shown in many experiments that the interaction efficiency and output power can be increased greatly by injecting plasma into the vacuum microwave device. Using field analysis, the dispersion characteristics and the interaction impedance of the disk-loaded waveguide filled with plasma are analyzed in a strong longitudinal magnetic field. In conclusion, the frequency of the TM₀₁ mode increases as the density of the plasma increases. It also can be found when the plasma density increases to a large scale, the TM₀₁ mode of the disk-loaded waveguide overlaps the TG mode, these two modes couple each other and form the new hybrid modes.     

MEMS封装技术研究进展

介绍了MEMS封装技术的特点、材料以及新技术,包括单片全集成MEMS封装、多芯片组件(MCM)封装、倒装芯片封装、准密封封装和模块式MEMS封装等。文中还介绍了MEMS产品封装实例。     

A Linear Cross-Coupled Control System for High-Speed Machining

We present a linear cross-coupled controller to improve highspeed contouring accuracy independently of tracking accuracy in a biaxial machine tool feed drive servomechanism. Unlike conventional cross-coupled controllers, the cross-coupled controller presented here is a linear system, so it is very easy to perform the stability and steady-state error analysis, and to optimise the controller parameters. The proposed controller is evaluated experimentally on a CNC LOM machine and compared to an uncoupled controller and a conventional cross-coupled controller. Controller performance is evaluated for a circular contour at a feedrate of 30 m min _1 . The experimental results show that the proposed controller can greatly reduce the contour error at large feedrates. The linear cross-coupled controller is simple to implement and is practical.     

Si1-xGex/Si应变材料的生长及热稳定性研究

利用分子束外延（MBE）技术生长了Ge组份为0.1-0.46的Si1-xGex外延层。X射线衍射线测试表明，SiGe/Si异质结材料具有良好的结晶质量和陡峭界面，其它参数与可准确控制。通过X射线双晶衍射摆曲线方法，研究了经700℃、800℃和900℃退火后应变SiGe/Si异质结材料的热稳定性。结果表明，随着退火温度的提高，应变层垂直应变逐渐减小，并发生了应变弛豫，导致晶体质量退化；且Ge组分越小，Si1-xGex应变结构的热稳定性越好；室温下长时间存放的应变材料性能稳定。     

Improvement of RCA transistor using RTA annealing after theformation of interfacial oxide

A polysilicon emitter RCA transistor (an ultra-thin interfacial oxide layer exists between polysilicon and silicon emitter) is presented which can operate at 77 K for the first time. An ultra-thin (1.5 nm) interfacial oxide layer is grown deliberately between polysilicon and silicon emitter using RCA oxidation and excellent device stability is obtained after rapid thermal annealing (RTA) treatment in nitrogen atmosphere. The RCA transistor exhibits good electrical performance at very low temperature for an emitter area of 3 × 8 μm². The maximum toggle frequency of a 1:2 static divider is 1.2 GHz and 732 MHz at 300 K and 77 K, respectively