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.     

多波段红外目标跟踪与辐射特性测量系统

介绍了一种对动态目标进行红外成像跟踪与辐射特性测量的系统。该系统采用大口径红外成像镜头，图像信号经放大、A／D转换和图像非均匀性校正，输出与目标辐射量成正比关系的数字图像信号。红外成像跟踪采用FPGA结合软件处理方法实现对目标的实时自动识别，进行形心、边缘与相关跟踪的计算。红外辐射特性测量采用基于PCI总线的高速图像采集板进行实时图像采集与显示。红外定标建立输出信号和标准黑体绝对辐射量的关系曲线，将原始的图像灰度数据换算为辐射通量密度。经外场试验证明该系统稳定可靠。     

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.     

Measurement and numerical simulation of three‐dimensional fiber orientation states in injection‐molded short‐fiber‐reinforced plastics

To determine three‐dimensional fiber orientation states in injection‐molded short‐fiber composites, a confocal laser scanning microscope (CLSM) is used. Since the CLSM optically sections the specimen, more than two images of the cross sections on and below the surface of the composite can be obtained. Three‐dimensional fiber orientation states can be determined by using geometric parameters of fiber images obtained from two parallel cross sections. For experiments, carbon‐fiber‐reinforced polystyrene is examined by the CLSM and geometric parameters of fibers on each cross‐sectional plane are measured by an image analysis. In order to describe fiber orientation states compactly, orientation tensors are determined at different positions of the prepared specimen. Three‐dimensional orientation states are obtained without any difficulty by determining the out‐of‐plane angles utilizing fiber images on two parallel planes acquired by the CLSM. Orientation states are different at different positions and show the shell–core structure along the thickness of the specimen. Fiber orientation tensors are predicted by a numerical analysis and the numerically predicted orientation states show good agreement with measured ones. However, some differences are found at the end of cavity. They may result from the fountain flow effects, which are not considered in the numerical analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 500–509, 2003     

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。     

黄海地质构造与油气资源

针对以往黄海油气勘探在找油思路、勘探深度、勘探领域、勘探部署和勘探技术等方面存在的问题 ,概述了南、北黄海地质构造、盆地演化、油气地质特征及成藏条件 ,并在此基础上 ,提出了对黄海油气资源远景的几点认识     

网络管理中事件关联检测机制的研究

网络事件的关联检测是网络管理需要解决的一个关键问题,本文根据分布式网络管理的特点,首次明确定义了网络事件的基本关联关系,在此基础上提出了一种基于Petri Net的事件关联检测机制,实现了基于事件内容的细粒度关联检测,并且在事件检测中充分考虑了时间因素,有效地提高了事件关联检测的准确性。     

Enhanced thermal stability of a sputtered titanium-nitride film as a diffusion barrier for capacitor-bottom electrodes

The effect of a thin RuO_x layer formed on the Ru/TiN/doped poly-Si/Si stack structure was compared with that on the RuO_x/TiN/doped poly-Si/Si stack structure over the post-deposition annealing temperature ranges of 450–600°C. The Ru/TiN/poly-Si/Si contact system exhibited linear behavior at forward bias with a small increase in the total resistance up to 600°C. The RuO_x/TiN/poly-Si/Si contact system exhibited nonlinear characteristics under forward bias at 450°C, which is attributed to no formation of a thin RuO_x layer at the RuO_x surface and porous-amorphous microstructure. In the former case, the addition of oxygen at the surface layer of the Ru film by pre-annealing leads to the formation of a thin RuO_x layer and chemically strong Ru-O bonds. This results from the retardation of oxygen diffusion caused by the discontinuity of diffusion paths. In particular, the RuO_x layer in a nonstoichiometric state is changed to the RuO₂-crystalline phase in a stoichiometric state after post-deposition annealing; this phase can act as an oxygen-capture layer. Therefore, it appears that the electrical properties of the Ru/TiN/poly-Si/Si contact system are better than those of the RuO_x/TiN/poly-Si/Si contact system.     

采用同心旋转调制盘的红外检测系统

介绍了采用同心旋转调制盘和相应的逻辑门积分计数的积累检测技术的基本原理，并给出采用同心旋转调制盘的红外检测系统的基本结构，介绍了同心旋转调制盘系统的设计方法，通过对实验结果进行分析，表明同心旋转调制盘技术在红外检测系统应用中可以大大地改善系统的性能，提高了探测概率，降低了虚警概率。同时分析了该系统存在的问题，为红外检测技术的进一步发展提供一些经验。