切入系统管理提升IT服务价值--IBM2005 TiVoli用户大会侧记

目前,频繁的宕机事件、难以预测的安全隐患、无法到位的IT服务,让企业的IT部门疲于应付,而居高不下的IT投资更是让IT部门备受非议。因此,改变IT服务管理的落后状况、提升IT的价值已势在必行,而在这方面,IBM的Tivoli有着相当强的优势,     

IP协议的作用、问题与发展战略思考(上)

从IP协议的内涵、作用与外延的一系列问题讨论出发，进一步论述发展IP及NGN的理性战略思维。     

Integrating PSONN and Boltzmann function for feature selection and classification of lymph nodes in ultrasound images

Lymph nodes (LNs), part of the lymphatic system, are important in the proper functioning of the immune system. LN metastasis is an important index for staging malignant tumors. The present study proposes a system that classifies lymph nodes according to pathological change from ultrasound (US) images. Features are selected and extracted from the US images. A feature selection method that integrates the particle swarm optimization neural network (PSONN) with the Boltzmann function is proposed to select significant features. A multi-class support vector machine (SVM) is adopted to classify diseases of the LN in the region of interests (ROIs) of US images into six categories. The experimental results show that the proposed approach decreases the number of selected features and that its classification is highly accurate.     

Multichannel MLSE equalizer with parametric FIR channelidentification

We propose a parametric finite impulse response (FIR) channel identification algorithm, apply the algorithm to a multichannel maximum likelihood sequential estimation (MLSE) equalizer using multiple antennas, and investigate the improvement in the overall bit error rate (BER) performance. By exploring the structure of the specular multipath channels, we are able to reduce the number of channel parameters to provide a better channel estimate for the MLSE equalizer. The analytic BER lower bounds of the proposed algorithm as well as those of several other conventional MLSE algorithms in the specular multipath Rayleigh-fading channels are derived. In the derivation, we consider the channel mismatch caused by the additive Gaussian noise and the finite-length channel approximation error. A handy-to-use simplified BER lower bound is also derived. Simulation results that illustrate the BER performance of the proposed algorithm in the global system for mobile communications (GSM) system are presented and compared to the analytic lower bounds     

The dynamic response analysis of a pyroelectric thin-film infraredsensor with thermal isolation improvement structure

Both theoretical and experimental studies of the substrate effect on the thermal behavior of a PbTiO₃ infrared (IR) sensor have been reported. With active cantilever dimensions of 200×100×5 μm³ formed by etching processes, the pyroelectric micro-electro-mechanical system (pyro/MEMS) structure exhibits a much superior performance to that of a traditional IR-sensing bulk structure under the 800-μW incident optical light with wavelength of 970 nm. Two-order improvement in current responsivity is obtained for the pyro/MEMS structure. This shows the substrate effect on the performance of a pyro/MEMS IR sensor is very significant. A simple model has also been proposed to illustrate the substrate effect more comprehensively     

Multistage interference cancellation with diversity reception forasynchronous QPSK DS/CDMA systems over multipath fading channels

This paper introduces a multistage interference cancellation (MIC) technique with diversity reception for quadrature phase shift keying (QPSK) asynchronous direct-sequence code division multiple access (DS/CDMA) systems over frequency-selective multipath Rayleigh fading channels. Unlike the previous MIC, which tries to remove the lump sum of the multiple-access interference (MAI) and self-interference (SI), this introduced MIC attempts to cancel only the MAI and part of the SI due to the intersymbol interference, while treating the remaining SI created by the current symbol as useful information for symbol decision. In this technique, the RAKE combining is used to collect signal replicas over multiple fading paths. Upper and lower bounds on the bit error probability are derived using a Gaussian approximation and the characteristic function method. Furthermore, effects of channel estimation error on the performance are studied. Analytical and simulation results show that the introduced MIC can provide a performance extremely close to that in an ideal single-user environment and outperforms the previous MIC even in the presence of channel estimation error     

激光淬火对钛合金高温干摩擦特性影响的实验研究

报道了钛合金TC11对轴承钢GCr15在室温到450℃大气环境下,激光淬火前后球盘对比研究。结果表明,经激光处理后,钛合金在150℃和300℃抗磨能力明显提高,但在室温和450℃改善不明显。     

飞秒钛宝石激光器Kerr透镜锁模动态的特性研究

研究了Kerr透镜锁模钛宝石激光器中腔内群色散改变时脉冲的动态特性。实验研究了腔内群色散改变时输出脉冲的频谱、中心波长以及脉宽的变化规律;观测和解释了脉冲频谱的双峰结构;给出了脉冲宽度与腔内色散的具体关系式;获得了最短为14.6fs的自锁模脉冲     

外加电场极化法制备LiNbO3铁电畴反转光栅

在室温下,应用外加电场极化法对z切0．5mm厚的LiNbO3晶体实现了铁电畴反转,并成功地制备了LiNbO3铁电畴反转光栅。