自适应SA-PSO优化的威布尔混合分布参数估计方法及应用

针对采用传统参数估计方法得到的模型拟合误差较大的问题,建立多重威布尔混合分布参数估计的非线性最小二乘模型,并提出基于模拟退火（SA）思想的自适应粒子群（PSO）算法进行求解。在PSO算法优化过程中,采用自适应方法调整惯性权重和加速因子,加快其收敛速度;引入模拟退火机制,根据Metropolis准则确定最优粒子的取舍,改善其全局搜索能力。将该方法应用到某型柴油机喷油器失效分布的参数估计中,并与图解法、基于Levenberg-Marquardt的非线性最小二乘法、标准PSO算法、自适应PSO算法求解的结果进行比较,分析所提方法的优化性能及精度。结果表明,该方法能够有效提高多重威布尔混合分布模型参数估计的精度和效率。     

高度定向的碳纳米管阵列的制备

使用99．99％的铝片．在草酸溶液中,通过基于自组织基础上的二次氧化法制备了孔高度有序、六角排列的氧化铝模板,在微米尺寸区域内获得了高度平行的氧化铝纳米孔阵列。利用化学气相沉积技术(CVD),在没有任何过渡金属催化剂的情况下,利用多孔氧化铝模板本身的催化作用,在氧化铝模板孔内成功制备了高度有序的平行碳纳米管阵列,这种碳纳米管阵列可以作为研究离子束沟道传输特性的较理想材料。利用扫描电子显微镜(SEM)和电子背散射衍射(EBSD)等测试手段对铝片、氧化铝模板和碳纳米管的结构进行了表征。讨论了氧化铝模板的形成机制和基于氧化铝模板生长高度定向碳纳米管的条件。     

高能物理实验中CAEN系列高压系统自动控制方案

针对高能物理实验中常用的CAEN系列高压系统SY1527、SY127／227,基于TCP／IP网络通讯技术、CAMAC总线技术、PCI总线技术和RS232串口总线通讯技术,实现并开发了适用于Linux／Win32系统不同版本的自动控制软件。用户可以依次编译独立的程序,按照设定自动开启,升降高压,并可实时监测高压系统的运行状态;亦可将此自动控制软件集成于数据获取系统,实现控制与采集同步,极大提高实验效率。     

Multi-mode hydrogen storage in nanocontainers

Hydrogen can be stored in containers or in materials (in molecular or atomic forms). The atomic form can further exist as multiple phases. Molecular hydrogen can be adsorbed on the surface or can be present inside the material. By invoking multiple modes of hydrogen storage, we establish a paradigm shift in the philosophy of hydrogen storage. Using a novel strategy of storage of molecular hydrogen in metal (Pd) nanocontainers, we observe that 18% hydrogen is in molecular form. Interestingly, this is achieved at 25 °C and 1 atm pressure; which is in contrast to storage in MOFs and carbonaceous materials like nanotubes. Enhancement in storage capacity as compared to Pd nanocrystals of the same mass is observed (36% increase at 1 atm & 25 °C), along with fast kinetics (0.5 wt% hydrogen absorption in 5 s). A new mechanism for hydrogen storage involving the dual catalytic role of Pd is established.     

基于碰撞的选择明文简单功耗聚类攻击算法(英文)

Chosen-message pair Simple Power Analysis (SPA) attacks were proposed by Boer, Yen and Homma, and are attack methods based on searches for collisions of modular multiplication. However, searching for collisions is difficult in real environments. To circumvent this problem, we propose the Simple Power Clustering Attack (SPCA), which can automatically identify the modular multiplication collision. The insignificant effects of collision attacks were validated in an Application Specific Integrated Circuit (ASIC) environment. After treatment with SPCA, the automatic secret key recognition rate increased to 99%.     

风电场功率控制策略研究与应用

文章根据国家电网对风电场功率控制的需求,提出了风电场功率控制方案。主要描述了风电场功率预测方法、降功率策略以及浅限幅、深限幅的具体策略。该方案经过现场实测,各项指标均达到国家电网要求。     

488天然气发动机的模拟计算

拟将一台CA4G22汽油机改为天然气专用发动机，为此对不同的技术方案进行了模拟计算。计算结果表明，采用增压中冷稀燃方案与理论空燃比方案相比，可以取得很好的动力性与经济性。     

Fermentative bioenergy production from distillers grains using mixed microflora

The feasibility of hydrogen production from distillers grains substrate, an industrial cellulosic waste, was investigated. A substrate concentration of 80 g/L gave the maximum production at 50 °C and pH of 6.0 using sewage sludge. Four controllable factors with three levels: seed sludge (two sewage sludges and cow dung), temperature (40, 50, and 60 °C), pH (6, 7 and 8) and seed pretreatment (none, heat, and acid) were selected in Taguchi experimental design to optimize fermentation conditions. The peak hydrogen and ethanol productions were found with heat-treated cow dung seed, substrate concentration 80 g/L, 50 °C and pH 6. The peak hydrogen production rate and hydrogen yield were 7.9 mmol H₂/L/d and 0.40 mmol H₂/g-COD respectively whereas the peak ethanol production was 3050 mg COD/L and rate 0.22 g EtOH/L/d. A total bioenergy yield of 41 J/g substrate was obtained which was 21% and 79% from hydrogen and ethanol respectively.     

Simulation of exhaust gas reforming of propane in a heat exchange integrated microchannel reactor

Exhaust gas reforming of propane to a hydrogen-rich mixture in a single, heat-exchange integrated, adiabatic, catalytic microchannel is modeled and simulated at different exhaust gas compositions from conventional gasoline and diesel fueled engines. Propane is considered as the model hydrocarbon for the complex fuels such as gasoline and diesel. The single microchannel is considered to be the characteristic unit of the catalytic exhaust gas reformer involving identical channels located parallel to each other. Steady-state simulations, carried out by the finite volume method, involve parametric variations of the total feed flow rate, and the amounts of propane and steam injected externally into the exhaust gas (reformer feed) stream. The results show that effective heat transfer and uniform temperature distribution, which are critical for the successful operation of the exhaust gas reformer, can be obtained in the microchannel configuration even at low gas hourly space velocities (GHSVs) at which the conventional packed-bed reformers usually lead to remarkable hot-spot formation. Production of H₂ and CO is favored by the addition of higher amounts of propane and steam into the reformer feed. Increasing the total feed flow rate, hence the GHSV is found to improve heat distribution along the microchannel at the expense of reduced product yields due to insufficient contact time.     

125I粒子植入与伽玛刀治疗门脉癌栓的疗效对比

【摘要】 目的 比较125I放射粒子植入与伽玛刀治疗门静脉癌栓的疗效,探讨其临床应用价值。方法 2009年1月—2013年5月的原发性肝癌合并门静脉癌栓的60例患者分为两组,30例采用伽玛刀治疗,计划设计3 ~ 10个靶点,单次剂量3 ~ 6 Gy, 2 ~ 5 次/周,照射总量30 ~ 50 Gy。治疗计划中50% ~ 70%等剂量曲线包绕计划靶区（PTV）。另30例采用125I放射粒子植入治疗,观察治疗后门静脉癌栓的变化。结果 治疗后3个月,伽玛刀组癌栓完全消失（CR）0例,部分缓解（PR）8例（26.6%）,无变化（SD）17例（56.7%）,进展（PD）5例（16.7%）;粒子植入组完全消失3例（10.0%）,部分缓解19例（63.4%）,无变化（SD）7例（23.3%）,进展（PD）1例（3.3%）。2组比较差异有统计学意义（P < 0.05）。2组在腹水及肝功能改善方面差异无统计学意义（P > 0.05）。结论 125I放射粒子植入治疗门静脉癌栓近期疗效优于伽玛刀,远期疗效有待于进一步研究。