构件化软件系统安全性分析技术研究

复杂系统的软件安全性分析中存在众多的含糊表述和不确定性问题,主观评价和模糊集理论即为处理此类问题的有效方法。首先对复杂软件涉及到的安全性要素进行模糊数学化表述,按照构件化的思想,对单个构件/模块的安全度进行分析,进而利用Dempster-Shafer证据理论对整个软件系统进行安全度综合,实现对软件系统的安全性分析和评估,最终按照DO-178B标准给出软件的安全等级,并通过实例加以说明。     

HDL代码风格对综合的影响深人探讨

目前综合器的优化功能越来越强,大部分设计都可以被优化。设计工程师也越来越依赖于综合工具,然而综合器的优化结果主要还是依靠设计工程师的代码风格。设计风格对综合结果的影响可以用一句话概括：“好的代码设计风格会使综合器事半功倍,达到最优的综合结果;不好的代码设计风格会使综合器南辕北辙,产生错误的综合结果。”有时候问题都源于其代码风格不尽合理,而并不在于综合器。     

Correlation of slurry reactor Fischer-Tropsch yield data

First stage slurry reactor Fischer-Tropsch (FT) yield data from Mobil's two-step pilot plant operations for the DOE have been correlated using a modified Schulz-Flory approach but allowing for changes in the probability of chain growth, , at key product molecular weights. Triple values of are invoked to explain (1) the high methane yield and (2) the very broad molecular weight distribution of the wax fraction, as compared to (3) moderate values of ₂ of between 0.79 and 0.85 for the C₂–C₂₀ hydrocarbons. Over this range, wax yields from 10 to 76 wt% are accommodated, at values of ₃ from 0.90 to 0.98. The second break in the yield-molecular weight curve occurs at the carbon number where most of the component remains in the reactor as liquid rather than leaving as vapor product. It is assumed that this is a function of vapor-liquid equilibrium. The correlation has proven useful in developing a computer model of the FT synthesis loop which is part of a baseline design and economic study for DOE/PETC.     

高性能众核处理器芯片时钟网络设计

随着芯片工艺演进与设计规模增加,高性能众核处理器芯片时钟网络设计面临时序和功耗的全方位挑战。为降低芯片时钟网络功耗并缓解时钟网络分布受片上偏差影响导致的时钟偏斜,在H-Tree+MESH混合时钟网络结构的基础上,结合新一代众核处理器芯片面积大及核心时钟网络分布广的特点,基于标准多源时钟树设计策略构建多源时钟树综合（MRCTS）结构,通过全局H-Tree时钟树保证芯片不同区域间时钟偏斜的稳定可控,利用局部时钟树综合进行关键路径的时序优化以实现时序收敛。实验结果表明,MRCTS能在保证时钟延时、时钟偏斜等性能参数可控的基础上,有效降低时钟网络的负载和功耗,大幅压缩综合子模块的布线资源,加速关键路径的时序收敛,并且在相同电源电压和时钟频率的实测条件下,可获得约22.15%的时钟网络功耗优化。     

Synthesis of Co/SiO2 hybrid nanocatalyst via twisted Co3Si2O5(OH)4 nanosheets for high-temperature Fischer-Tropsch reaction

A cobalt-silica hybrid nanocatalyst bearing small cobalt particles of diameter ～5 nm was prepared through a hydrothermal reaction and hydrogen reduction.The resulting material showed very high CO conversion (＞82％) and high hydrocarbon productivity (～1.0 gHc·g-1cat,·h-11) with high activity (～8.5 x 10-5 molco·g-1Co·S-1) in the Fischer-Tropsch synthesis reaction.     

Spark discharge generator as a stable and reliable nanoparticle synthesis device: Analysis of the impact of process and circuit variables on the characteristics of synthesized nanoparticles

Nanotechnology offers the promise of harnessing quantum properties not available in the bulk phase. These desirable properties are highly dependent on size and composition. Generators that control these variables are therefore essential for progress in the field. The spark discharge generator (SDG) is an outstanding aerosol route for nanoparticle synthesis, which stands out due to its fast kinetics, scalability, high purity, accuracy and reproducibility, with the added advantage of allowing the synthesis of nanoparticles of any conducting material. These advantages are a consequence of its vast heating and cooling rates, its intrinsic and easily controllable electronic variables at the reach of a click. However, the mechanistic impact of these variables on the actual aerosol generated is still not fully understood. In this work, we constructed an SDG and systematically studied its behavior with particular interest in the effect that resistance, capacitance, inductance, flow rate, gap separation and current have on the electrical behavior of the spark. Our model system produced primarily Fe and Cu nanoparticles with measured concentrations ranging 5*10⁵ – 2*10⁷ part/cm³, and mean agglomerate sizes of 5 – 80 nm. We discuss how the spark influences particle size and number concentration and provide useful correlations that link dependent with independent variables. Remarkably, a finite resistance produces a maximum in the output of the generated aerosols. This suggests a direct link between RLC properties of the circuit and cabling into the frequency of the spark, and nanoparticle number concentration, indicating potential for exploiting such behavior towards maximizing nanoparticle generation. Furthermore, we discuss a link between spark oscillations and energy release with its consequent aerosol generation.     

RTL设计中的Verilog代码风格

RTL设计中的Verilog代码风格对综合后的硬件结构起至关重要的作用,相同功能不同风格的代码在综合后可能会产生不同的结构,具有不同的timing和area。     

Synthesis a Petri net based control model for a FMS cell

Petri nets have been recognised as a high level formal and graphical specification language for modelling, analysis, and control of concurrent asynchronous distributed systems. This paper presents a PN model, synthesised by an extended version of the knitting synthesis technique. This method, as an incremental design approach, establishes the conditions under which the fundamental behavioural properties of the synthesised systems are fulfilled and preserved. That is, the synthesised models are live, bounded, and reversible (cyclic). A Petri net with the aforementioned properties is called a well-behaved Petri net system which is guaranteed to operate in a deadlock-free, stable, and cyclic fashion. Well-behaved Petri net models, synthesised using the proposed method can be compiled into control codes and implemented as real-time controllers for flexible manufacturing systems. The significance of this paper is due to the application of an extended version of knitting synthesis technique to a real life example of a flexible manufacturing system.     

焦炉配煤专家系统的定性定量综合设计方法

焦炉配煤炼焦过程是存在诸多不确定性、无法用数学模型描述的复杂工业过程,传 统控制方法难以实施控制.根据焦化理论和生产所获工业数据构造数学模型,以群体专家经 验得到的定性知识构成规则模型,将解析的数学模型与基于知识的规则模型相结合,采用定 性定量综合集成方法,建立焦炭质量预测模型,提出了配煤比计算的实用算法,并实时控制配 煤流量.系统于1994年正式投入工厂运行,焦炭质量预测精度达到95％,配煤准确率达到 97％.工业运行结果证明了方法的有效性.     

VHDL语言设计可综合的微处理器内核*

详细介绍了用VHDL语言设计可逻辑综合的教学实验用CPU的过程。CPU指令系统构架采用RISC结构,设计上使用结构化编程方法,将CPU内核按照功能划分为不同的模块,采用VHDL语言设计每一个模块的内部功能和外围接口。所有的功能模块组合起来后,通过EDA工具进行CPU内核的逻辑综合和功能仿真,最后在可编程逻辑器件上实现这个完整的CPU内核。