化学复合镀层激光处理研究

研究了激光处理对Ni-P -SiC化学复合镀层的影响。借助于扫描电镜、能谱仪、X射线衍射、显微硬度计等设备对激光处理后复合镀层的表面形貌、组织结构及性能进行了综合分析。结果表明 ,对复合镀层进行激光处理可以获得与炉内加热同样的镀层硬度 ,且当激光功率 4 0 0W ,扫描速度 1.5m /min时 ,镀层硬度高于炉内加热的硬度     

Near-ML multiuser detection with linear filters and reliability-based processing

The prohibitive - exponential in the number of users - computational complexity of the maximum-likelihood multiuser detector for direct-sequence code-division multiple-access communications has fueled an extensive research effort for the development of low-complexity multiuser detection alternatives. We show that we can efficiently and effectively approach the error rate performance of the optimum multiuser detector as follows. We utilize a multiuser zero-forcing or minimum mean-square error (MMSE) linear filter as a preprocessor and we establish that the output magnitudes, when properly scaled, provide a reliability measure for each user bit decision. Then, we prepare an ordered, reliability-based error search sequence of length linear in the number of users; it returns the most likely user bit vector among all visited options. Numerical and simulation studies for moderately loaded systems that permit exact implementation of the optimum detector indicate that the error rate performance of the optimum and the proposed detector are nearly indistinguishable over the whole predetection. signal-to-noise ratio range of practical interest. Similar studies for higher user loads (that prohibit comparisons with the optimum detector) demonstrate error rate performance gains of orders of magnitude in comparison with straight decorrelating or MMSE multiuser detection.     

Characteristics of low-leakage deep-trench diode for ESD protection design in 0.18-/spl mu/m SiGe BiCMOS process

This paper proposes a novel low-leakage BiCMOS deep-trench (DT) diode in a 0.18-/spl mu/m silicon germanium (SiGe) BiCMOS process. By means of the DT and an n/sup +/ buried layer in the SiGe BiCMOS process, a parasitic vertical p-n-p bipolar transistor with an open-base configuration is formed in the BiCMOS DT diode. Based on the two-dimensional (2-D) simulation and measured results, the BiCMOS DT diode indeed has the lowest substrate leakage current as compared to the conventional p/sup +//n-well diode even at high temperature conditions, which mainly results from the existence of the parasitic open-base bipolar transistor. Considering the applications of the diode string in electrostatic discharge (ESD) protection circuit designs, the BiCMOS DT diode string also provides a good ESD performance. Owing to the characteristics of the low leakage current and high ESD robustness, it is very convenient for circuit designers to use the BiCMOS DT diode string in their IC designs.     

单元串联式多电平高压变频器的起源、现状和展望

本文对单元串联式多电平高压变频器的起源和现状进行了总结,同时从无速度传感器矢量控制、大容量化、冗余设计等方面对该技术未来的发展趋势进行了展望。     

Mobile Device Security Using Transient Authentication

Mobile devices are vulnerable to theft and loss due to their small size and the characteristics of their common usage environment. Since they allow users to work while away from their desk, they are most useful in public locations and while traveling. Unfortunately, this is also where they are most at risk. Existing schemes for securing data either do not protect the device after it is stolen or require bothersome reauthentication. Transient Authentication lifts the burden of authentication from the user by use of a wearable token that constantly attests to the user's presence. When the user departs, the token and device lose contact and the device secures itself. We show how to leverage this authentication framework to secure all the memory and storage locations on a device into which secrets may creep. Our evaluation shows this is done without inconveniencing the user, while imposing a minimal performance overhead     

InGaN microring light-emitting diodes

The fabrication and performance of an InGaN light-emitting diode (LED) array based on a microring device geometry is reported. This design has been adopted in order to increase the surface area for light extraction and to minimize losses due to internal reflections and reabsorption. Electrical characteristics of these devices are similar to those of a conventional large-area LED, while the directed light extraction proves to be superior. In fact, these devices are found to be more efficient when operated at higher currents. This may be attributed to improved heat sinking due to the large surface area to volume ratio. The potential applications of these devices are also discussed.     

Search for high-performance probe-fed stacked patches using optimization

High-performance circular probe-fed stacked patch antenna designs are explored through the use of numerical optimization. New trends are sought to aid understanding and to suggest novel solutions. We describe the optimization technique, present a new design trend relating efficiency and bandwidth to the choice of substrate dielectric, and propose and demonstrate a novel, optimized antenna achieving 33% bandwidth whilst maintaining greater than 80% surface wave efficiency.     

运营商内部数据通信网的VPN技术

针对电信运营商在构建内部数据通信网(DCN)时遇到的各应用系统的隔离问题，详细介绍了目前几种主流的虚拟专用网(VPN)技术，并进行分析比较，最后提出了运营商内部数据通信网的VPN解决方案。     

On the capacities of bipartite Hamiltonians and unitary gates

We consider interactions as bidirectional channels. We investigate the capacities for interaction Hamiltonians and nonlocal unitary gates to generate entanglement and transmit classical information. We give analytic expressions for the entanglement generating capacity and entanglement-assisted one-way classical communication capacity of interactions, and show that these quantities are additive, so that the asymptotic capacities equal the corresponding 1-shot capacities. We give general bounds on other capacities, discuss some examples, and conclude with some open questions.     

Pseudorandom active UWB reflectors for accurate ranging

In this letter, the concept of pseudorandom active reflector, based on the ultra-wideband (UWB) technology, is introduced. It consists of a simple device that repeats a slightly delayed version of the received UWB signal only in certain time intervals according to a suitable pseudorandom time-hopping sequence. An example of application of this device for accurate ranging in precise location systems is given. The advantages of this solution are in the hardware simplicity (only the analog section is present), in the low power consumption of the reflector and in the low timing constraint regarding the relative transmitter and reflector clock rates.