现役水工钢闸门结构可靠性鉴定时荷载取值分析

采用类比法确定现役水工钢闸门结构的荷载评估基准期。以静水压力为例，得了其在荷载评估基准期内的统计参数，讨论了闸门主梁受弯碱坏时可靠指标随继续使用期的变化。     

测量光纤放大器小信号增益谱的一种简便方法

提出了一种用小功率宽带光源较精确测量光纤放大器小信号增益谱的方法。数值模拟表明 ,该方法是完全可行的 ,并且实验结果与数值模拟结果一致。该方法具有简便、易操作的特点。     

Performance analysis of OFDMA uplink systems with symbol timing misalignment

This letter presents our investigation for the effect of symbol timing errors in orthogonal frequency-division multiple access (OFDMA) uplink systems. We express the symbol timing errors between users as the symbol timing misalignments with respect to the desired user. Then, we derive an explicit expression of the signal-to-noise ratio (SNR) as a function of the maximum value of the symbol timing misalignments. Analyses and simulation results show that, to achieve an SNR of 20 dB, the maximum value of the symbol timing misalignments must be less than the cyclic prefix duration plus 6.25% of the useful symbol duration. Based on the resulting SNR degradation, we evaluate the SNR gain with guard subcarriers in order to mitigate the effect of the symbol timing misalignments.     

试论循环水装置的经济性及其成本分析

通过对循环水装置的投资和成本分析，阐述了建设该装置的经济性和社会意义。     

Estimating and reducing the memory requirements of signal processing codes for embedded systems

Most embedded systems have limited amount of memory. In contrast, the memory requirements of the digital signal processing (DSP) and video processing codes (in nested loops, in particular) running on embedded systems is significant. This paper addresses the problem of estimating and reducing the amount of memory needed for transfers of data in embedded systems. First, the problem of estimating the region associated with a statement or the set of elements referenced by a statement during the execution of nested loops is analyzed. For a fixed execution ordering, a quantitative analysis of the number of elements referenced is presented; exact expressions for uniformly generated references and a close upper and lower bound for nonuniformly generated references are derived. Second, in addition to presenting an algorithm that computes the total memory required, this paper also discusses the effect of transformations (that change the execution ordering) on the lifetimes of array variables, i.e., the time between the first and last accesses to a given array location. The term maximum window size is introduced, and quantitative expressions are derived to compute the maximum window size. A detailed analysis of the effect of unimodular transformations on data locality, including the calculation of the maximum window size, is presented.     

肉制品调香调味基础理论综述

阐述了加工肉制品调香调味设计基本原则、基本步骤、基本技巧，并详细介绍了肉味香精的特点及正确鉴别、选择和使用的方法。     

MCM-41掺杂Cr对正己醇催化活性的影响

合成了掺杂不同Cr含量的Cr-MCM-41分子筛,采用XRD、FT-IR等手段对催化剂进行了表征,并考察了它们对正己醇催化氧化性能的影响.结果表明,掺杂适量的Cr,可使正己醇的转化率达到48%,正己酸的选择性达到83%.Cr的掺杂量、反应温度、催化剂用量等条件对该催化反应均有一定影响.适量杂原子的掺杂不会破坏MCM-41分子筛的结构.     

MIP汽油性质及其深度加氢脱硫性能的研究

分析了我国典型炼油厂FCC汽油硫含量和烯烃含量的变化情况,将MIP汽油[采用多产异构烷烃FCC工艺(Maximizing Iso-Paraffins)生产的汽油],与常规FCC汽油的性质进行了比较,介绍了用OCT-M技术(FCC汽油选择性加氢脱硫技术)对MIP汽油进行深度加氢脱硫的研究情况,包括加工方案的比较、反应压力的影响.结果表明,OCT-M FCC汽油选择性加氢脱硫技术可以将烯烃体积分数为31%的MIP汽油的硫质量分数由664 μg/g降低到50 μg/g以下,研究法辛烷值损失0.7～1.7,OCT-M技术能够为我国炼油厂由MIP汽油生产符合欧Ⅳ标准的清洁汽油提供灵活、经济的技术解决方案.     

Ca掺杂钨镁酸铅陶瓷材料的制备及其介电性能

研究了Ca掺杂钨镁酸铅(PMW)陶瓷材料的合成、结构、烧结以及介电性能。结果发现：在Ca^2 摩尔分数小于15％时，能形成单相的PCMW钙铁矿相，结构由原来的斜方相向立方相转变。用二步合成法制备的样品容易致密烧结，气孔率比一步法制备的样品小。Ca的加入降低了材料的介电损耗，在频率为1MHz时，介质损耗达到了10^-4。当Ca^2 摩尔分数大于10％时，材料的Curie峰宽化显著，介电常数温度系数降低。     

激光熔覆专用铁基合金粉末的研究进展

指出了目前防止熔覆层开裂所采取的主要措施中存在的问题,阐述了激光熔覆和热喷涂对于所用合金粉末性能要求之异同,评述了激光熔覆专用铁基合金粉末的研制现状,提出了成分与组织设计的新思想。