用250μm常规光纤进行光纤带研制和生产

为制成特大芯数和超高密集型光缆，采用２５０μｍ常规光纤，以不同的结构和涂层试制了４芯，８芯，１２芯光纤带，通过一系列的试验和测试，了解到光纤带的光性能取决于涂层结构（如边粘式和包复式）涂层材料的杨氏模量以及涂层厚度，确定了适合目前工厂生产情况的光纤带生产技术。     

A fault-tolerant protocol for election in chordal-ring networkswith fail-stop processor failures

In a distributed computer system, a group of processors is connected by communication links into a network. Each processor (node) of the network has an identity (a unique integer value) that is not related to its position in the network (its address). A processor's identity is known only to the processor. In the problem of leader election, exactly one processor among a network of processors has to be distinguished as the leader. Previously, many efficient election protocols have been proposed for networks with a sense of direction. In particular, the sequential search is used for election in a reliable complete network, and a multi-token search method is used in a faulty complete network. However, election protocols on a faulty ChRgN (chordal ring network) have not been investigated by other researchers. This paper addresses this issue by: studying the problem of leader election in an asynchronous ChRgN with a sense of direction and with the presence of undetectable fail-stop processor failures; proposing a new election protocol which (a) combines the concept of sequential search and multi-token search techniques, and (b) uses an efficient routing algorithm to reduce the total number of messages used; presenting a protocol for a ChRgN of n processors with I chords/processor and at most f fail-stop faulty processors, with message complexity O(n+(n/l)log(n)+k·f), where k is the number of processors starting the election process spontaneously and at most f相似文献   

Reliability prediction of imperfect switching systems subject to multiple stresses

Reliability prediction plays a very important role in system design, and the two key factors considered in predicting system reliability are: failure distribution of the component/equipment and system configuration. This paper discusses about the imperfect switching system with one component in active and k spares in the standby state. When the operating component breaks down, the switch will be able to detect the failure using the sensor and replace the defective component with a functionable spare, so the system can keep operating. Therefore, the switch and the sensor have direct impact on normal operations of the switching systems.The reliability of two types of imperfect switching system is thoroughly discussed and compared: (1) a non-repairable system with only one standby component, one switch and one sensor and (2) a non-repairable system with two standby components, one switch and one sensor. Since gamma distribution is fairly adequate to describe the failure mechanism of a system under k-times of shock multiple stresses. This paper then assumes in system (1) and (2), the operating components follow gamma failures, sensor and switch failures follow exponential distribution. In addition, three modes are assumed in regards to the switch failure: under energized, under failing-open and under failing-closed condition.This paper uses MAPLE computer language to perform reliability estimation and comparison on the above-mentioned systems with components, switch and sensor under different failure rate and various intended period of use. Its results can provide guidelines on decision making for improving system design in industries.     

Bound for Minkowski metric or quadratic metric applied to VQcodeword search

A bound for a Minkowski metric based on L_p distortion measure is proposed and evaluated as a means to reduce the computation in vector quantisation. This bound provides a better criterion than the absolute error inequality (AEI) elimination rule on the Euclidean distortion measure. For the Minkowski metric of order n, this bound contributes the elimination criterion from the L₁ metric to L _n metric. This bound can also be an extended quadratic metric which can be a hidden Markov model (HMM) with a Gaussian mixture probability density function (PDF). In speech recognition, the HMM with the Gaussian mixture VQ codebook PDF has been shown to be a promising method     

国产首台300MW燃油直流炉机组的化学水处理工作

本文回顾和总结了望亭电厂第一台国产300MW机组的化学水处理及监督工作,文章强调了慎重选择补给水源和预处理的重要性,并指出补给水处理设备应能满足水源水质变化的要求,否则要有应急措施;应提高凝结水精处理的质量,以确保给水水质;给水联合处理将为减轻水汽系统和锅内腐蚀、结垢开创新的途径:认真执行有效的机、炉停用保护措施:防止凝汽器和热交换器管泄漏以及逐步实现化学监督现代化管理是大机组防腐防垢的重要内容。     

Turn-on voltage investigation of GaAs-based bipolar transistors with Ga/sub 1-x/In/sub x/As/sub 1-y/N/sub y/ base layers

The fundamental lower limit on the turn on voltage of GaAs-based bipolar transistors is first established, then reduced with the use of a novel low energy-gap base material, Ga/sub 1-x/In/sub x/As/sub 1-y/N/sub y/. InGaP/GaInAsN DHBTs (x/spl sim/3y/spl sim/0.01) with high p-type doping levels (/spl sim/3/spl times/10/sup 19/ cm/sup -3/) and dc current gain (/spl beta//sub max//spl sim/68 at 234 /spl Omega///spl square/) are demonstrated. A reduction in the turn-on voltage over a wide range of practical base sheet resistance values (100 to 400 /spl Omega///spl square/) is established relative to both GaAs BJTs and conventional InGaP/GaAs HBTs with optimized base-emitter interfaces-over 25 mV in heavily doped, high dc current gain samples. The potential to engineer turn-on voltages comparable to Si- or InP-based bipolar devices on a GaAs platform is enabled by the use of lattice matched Ga/sub 1-x/In/sub x/As/sub 1-y/N/sub y/ alloys, which can simultaneously reduce the energy-gap and balance the lattice constant of the base layer when x/spl sim/3y.     

Half-time image reconstruction in thermoacoustic tomography

Thermoacoustic tomography (TAT) is an emerging imaging technique with great potential for a wide range of biomedical imaging applications. In this paper, we propose and investigate reconstruction approaches for TAT that are based on the half-time reflectivity tomography paradigm. We reveal that half-time reconstruction approaches permit for the explicit control of statistically complementary information that can result in the optimal reduction of image variances. We also show that half-time reconstruction approaches can mitigate image artifacts due to heterogeneous acoustic properties of an object. Reconstructed images and numerical results produced from simulated and experimental TAT measurement data are employed to demonstrate these effects.     

A 2.4-GHz CMOS transceiver for Bluetooth

A fully integrated CMOS transceiver tuned to 2.4 GHz consumes 46 mA in receive mode and 47 mA in transmit mode from a 2.7-V supply. It includes all the receive and transmit building blocks, such as frequency synthesizer, voltage-controlled oscillator (VCO), power amplifier, and demodulator. The receiver uses a low-IF architecture for higher level of integration and lower power consumption. It achieves a sensitivity of -82 dBm at 0.1% BER, and a third-order input intercept point (IIP3) of -7 dBm. The direct-conversion transmitter delivers a GFSK modulated spectrum at a nominal output power of 4 dBm. The on-chip voltage controlled oscillator has a close-in phase-noise of -120 dBc/Hz at 3-MHz offset     

High quality interpoly dielectrics deposited on thenitrided-polysilicon for nonvolatile memory devices

High quality interpoly dielectrics have been fabricated by using NH₃ and N₂O nitridation on polysilicon and deposition of tetra-ethyl-ortho-silicate (TEOS) oxide with N₂O annealing. The surface roughness of polysilicon is improved and the value of weak bonds is reduced due to nitrogen incorporation at the interface, which improves the integrity of interpoly dielectrics. The improvements include a higher barrier height, breakdown strength, and charge-to-breakdown, and a lower leakage current and charge trapping rate than counterparts. It is found that this method can simultaneously improve both charge-to-breakdown (up to 20 C/cm² ) and electric breakdown field (up to 17 MV/cm)