精轧油膜轴承密封失效机理的初步分析

对油膜轴承密封出现的进水、漏油现象作了大量的调查、测量和统计分析，找出了产生质量事故的根本原因，提出了解决措施。     

Deorthogonalization of ODS-CDMA QPSK by AM/PM Nonlinearity

When using a conventional demodulator, a sufficient condition to maintain ODS-CDMA codeword orthogonality is constant relative channel amplitude over the codeword duration. When transmitted over a memoryless, AM/PM nonlinearity channel, the chip-to-chip fluctuating amplitude of a composite ODS-CDMA QPSK waveform produces a chip-to-chip fluctuating phase that deorthogonalizes the ODS-CDMA codewords, resulting in an additional multiple access self-interference similar to that found in asynchronous DS-CDMA. For ODS-CDMA QPSK in an AM/PM nonlinearity channel, we utilize the Central Limit Theorem, derive, and evaluate: (i) an expression for the signal-to-distortion ratio at the demodulator output, (ii) an expression for the uncoded bit error probability, and (iii) an upper bound on the convolutionally-coded bit error probability. We find that the degradation to BER depends on both the AM/PM nonlinearity slope and the ODS-CDMA channel loading.     

Stereological estimation of the total volume of MR visible brain lesions in patients with multiple sclerosis

Point counting represents a convenient and efficient technique for estimating the area of transects through multiple sclerosis (MS) lesions on magnetic resonance (MR) images obtained for sections through the brain. When sectioning has been performed according to the Cavalieri method, unbiased estimates of the total volume of MR-visible MS plaques can be obtained with a precision of 3–5% in 5–10 min.     

Fault-accommodation with intelligent sensors

Optimal sensor fault-accommodation is considered for faults modelled by an increase in measurement noise. This noise is taken to be bounded and its probabilistic properties unknown. It is assumed that intelligent (e.g. self-validating) instrumentation is in use and estimates of the noise bounds are available. The fault-tolerant controller is designed to optimize a noise rejection and a nominal reference tracking index and leads to a mixed norm minimization problem (l₁/l₂). We exploit known results and a particular feedback configuration to show that it is possible to optimize simultaneously without a trade-off the two performance indices. The results are applied to systems where the presence of auxiliary measurements allows for an optimal fault-accommodation strategy. Using properties of the optimal solution, we define a factorization for the optimal controller alternative to the Youla parametrization, leading to an algorithm which is optimal, transparent and efficient.     

Macha爆炸机故障维修十一例

随着Macha遥爆系统在地震勘探中使用年限的增加，该系统在工作中时常出现各种各样的故障，本文根据其日常检修记录，分析总结了Macha系统常见的十一例故障，并从故障的现象、分析、排除三个方面对各个故障进行了详细的介绍。     

大庆油田水平井分流压裂技术

水平井分流压裂的技术原理是将水平井的水平段分成若干个单元，在每个单元的最佳部位进行射孔，每段的射孔数由孔径、单元数、设计施工排量等参数决定，射孔方案为压裂方案的有机组成部分。大庆油田已有5口水平井实施分流压裂，根据油层厚度分为两类：裂缝限制在油层内和裂缝穿透隔层贯穿多个薄油层。通过肇57-平35井和肇57-平33井进行的分流压裂贯穿多个油层现场试验，介绍了大庆油田水平井分流压裂的设计方法、压裂液体系、现场施工控制方法和效果分析方法。微地震裂缝监测结果表明，在最大施工排量7．5m^3／mim条件下，一次施工形成3～4条裂缝，加砂量最大达到75m^3（陶粒），平均砂比达到35％以上。水平井采用分流压裂技术施工后，初期产能可达到相邻直井压裂后产能的2．0倍以上。如何检测裂缝是否穿透了隔层并贯穿多个油层，是指导水平井分流压裂技术的选井选层，提高压裂效果的关键技术。图8表2参2。     

疏松砂岩地层出砂对套管损坏的研究

以东濮凹陷文明寨油田历年井况调查的套管损坏资料为依据，在对出砂油井套管损坏形态、层位与射孔状况、岩石性质等因素进行综合分析基础上，对疏松砂岩出砂、上覆岩层坍塌等主要方面导致的套管受力变形进行研究，为探讨防治措施提供依据。     

DIN-100MnCrW4模具钢开裂原因分析

对DIN－100MnCrW4模具钢开裂原因进行了分析。结果表明，模具钢 属淬火开裂，主要原因是材料内部组织不均匀所致。     

Performance Evaluation of Packet Mobile Communications through Level Crossing Analysis

In this paper the performance of a packet mobile radio network is studied inthe presence of shadow fading outage intervals.Under quite general assumptions for the medium access protocol,the probability mass function of the sequence of packets that may be lostdue to an outage interval is derived. It is seen that long sequences of lostpackets are likely to occur for typical values of the mobile speed andshadowing correlation parameters.For delay constrained sources, e.g., voice, the analysis is mainly focused atderiving the probability function of the sequence of dropped packetsand the probability of dropping. For data sources, the delay statistic isalso derived. In the latter case, the effect of finite buffer length isaddressed. Simulation is used to verify the accuracy of approximations introduced in the analysis.     

多目标模糊优选理论在水资源系统中的应用

开放的水资源系统分析理论应是水资源学与系统科学等多种学科的结合 ,介绍一种新兴而实用的水资源系统分析技术———半结构性决策系统模糊优选理论的基本原理及其应用。