产低温纤维素酶南极细菌的筛选、生长特性及酶学性质的初步研究

以南极海冰细菌作为实验材料,用刚果红染色和发酵培养法从64株细菌中筛选得到产纤维素酶菌株Pseudoalteromonassp.545。经生长条件优化,该菌以麦芽糖为碳源,蛋白胨为氮源,初始生长pH为8.0,10℃培养96h时产酶最高。对菌株粗酶液进行酶学性质初步研究,此酶在pH9.0、35℃下反应40min时酶活最高。另外,该菌株所产纤维素酶在0～60℃范围内均有活性,属于低温酶。     

己唑醇在苹果和土壤中的残留及安全使用评价

[方法]采用田间试验的方法,对己唑醇在苹果及土壤中的残留消解动态及最终残留量进行了研究.气相色谱电子捕获检测器进行定量分析.[结果]消解动态试验结果表明:己唑醇在土壤中的半衰期为7.1～14.4 d,在苹果中的半衰期为7.1～8.8 d;最终残留量试验结果表明:5％己唑醇悬浮剂按施药剂量为50、75 mg a.i./kg,连续喷药3～4次,施药间隔期7d,喷药后21 d土壤中已唑醇残留量＜0.01～0.215 mg/kg,苹果中已唑醇残留量为0.011～0.055 mg/kg,均低于0.1 mg/kg(MRL).[结论]推荐5％已唑醇悬浮剂在苹果上使用安全间隔期为21 d.     

采用全阶状态观测器的IGBT模块结温预测

为解决控制器功率器件过温失效问题,需要对IGBT的PN结温度进行实时精确估计.设计全阶状态观测器对IGBT的结温进行实时估计,并综合考虑电、热参数的相互影响,采用闭环控制实现结温的估计修正;根据双脉冲测试原理搭建IGBT动态特性离线测试平台,研究导通电流、母线电压、结温对IGBT损耗的影响,采用线性插值法推导IGBT损...     

自适应扩展卡尔曼滤波电池荷电状态估算方法

为更精确预估电动汽车动力源的荷电状态,优化戴维南等效电路模型,用自适应扩展卡尔曼滤波进行荷电状态估算.对实验电池进行外特性数据获取实验,分别得到在充放电状态下的开路电压曲线,在开路电压-荷电状态对应曲线中考虑充放电状态变化的因素.对离线参数辨识进行优化处理,在固定参数离线辨识的基础上考虑充放电状态和荷电状态,并与在线辨...     

Optical properties and cooling performance analyses of single-layer radiative cooling coating with mixture of TiO2 particles and SiO2 particles

Radiative cooling can achieve cooling effect without consuming any energy by delivering energy into outer space(3K) through"atmospheric window"(8–13 μm). Conventional radiative cooling coating with multi-layer structure was severely restricted during application due to its complex preparation process and high cost. In this study, a single-layer radiative cooling coating with mixture of TiO_2 particles and SiO_2 particles was proposed. The algorithm for calculating the radiative properties of the multi-particle system was developed. Monte Carlo ray-tracing method combined with that algorithm was used to solve the radiative transfer equation(RTE) of the single-layer radiative cooling coating with mixture of TiO_2 particles and SiO_2 particles.The effects of particle diameter, volume fraction and coating thickness on radiative cooling performance were analyzed to obtain the best radiative cooling performance. The numerical results indicated that the average reflectivity of the single-layer radiative cooling coating with mixture of TiO_2 particles and SiO_2 particles in the solar spectrum can reach 95.6%, while and the average emissivity in the "atmospheric window" spectrum can reach 94.9% without additional silver-reflectance layer. The average reflectivity in the solar spectrum and average emissivity in the "atmospheric window" spectrum of the single-layer radiative cooling coating with mixture of TiO_2 particles and SiO_2 particles can increase 4.6% and 4.8% compared to the double-layer radiative cooling coating. This numerical research results can provide a theoretical guidance for design and optimization of single-layer radiative cooling coatings containing mixed nanoparticles.     

软件测试资源与成本管控和最优发布策略

为全面系统地了解软件测试过程中与可靠性相关的重要过程的研究现状和最新发展,对测试资源和成本的管理,以及最优发布技术问题进行了深入研究。首先将研究问题划分为4类,剖析了测试资源分配与控制,成本模型和最优发布基本内容,给出了其公式化的形式化描述和内在关系;然后从软件体系结构建模、测试过程建模、非线性最优化与仿真求解3个方面进行了技术分类评述。进一步将研究内容从5个方面进行归一化分类,并对选取的典型模型进行了归类比较总结。最后,指出了进一步研究发展的主要问题。研究分析表明,测试资源分配与成本管控和最优发布策略中,考虑到软件体系结构特征和不完美排错模型,向多目标融合方向发展,并与可靠性评估相关是后续研究的研究。     

Approach to an FE simulation of coating damage on bulk metal forming tools

This paper describes the numerical simulation of failure mechanisms of coated forming tools and explains the procedure of a finite element analysis (FEA) of the coating - substrate - system.The development of a static failure model is explained using the examples of thermally sprayed and amorphous carbon coatings. Furthermore, its implementation into the FE model is demonstrated. Sprayed thick coatings are used initially, the developed methods are then transferred to amorphous thin coatings. Necessary thermomechanical material properties, especially in the case of thin coatings, as well as system characteristics such as adhesion strength are insufficiently known. Together with FEA several techniques are employed to determine applicable model parameters using parameter identification. The paper only considers monolayers. In a first approximation both substrate and coating are considered homogeneous and isotropic.     

Joining ZTA ceramic by using Dy2O3-Al2O3-SiO2 glass ceramic filler

In this paper, a novel Dy₂O₃-Al₂O₃-SiO₂ (DAS) glass ceramic was designed and prepared for joining zirconia toughened alumina (ZTA) ceramic. The crystallization, thermal expansion behavior and wetting behavior of the DAS glass filler were studied. The effect of cooling rate and joining temperature on the microstructure and flexural strength of joints was investigated. The results show that slow cooling rate (15 °C/min) leads to crystallization of brazing seam, which causes the formation of pores in the joints due to the large density difference between the glass and the crystalline phases. The dissolution of ZrO₂ from ZTA substrate into the filler during joining process improves the mismatch of the coefficient of thermal expansion (CTE) between the brazing seam and substrate. The maximum flexural strength of 535 MPa is obtained when the joining temperature and cooling rate are 1475 °C and 50 °C/min, respectively.     

Physicochemical and thermo physical characterization of CaO–CaF2–SiO2 and CaO–TiO2–SiO2 based electrode coating for offshore welds

This paper investigates the physicochemical and thermo-physical properties of CaO–CaF₂–SiO₂ and CaO–TiO₂–SiO₂ based electrode coating for welding offshore structures. Twenty-one electrode coating compositions have been formulated using extreme vertices design method. The coating was crushed to powder form. The powder was characterized for weight loss, density, specific heat, enthalpy, thermal conductivity, diffusivity, and specific heat. Coating's structural analysis was done using X-Ray Diffraction and Fourier transformation. X-Ray Fluorescence, Thermogravimetric Analyzer, and Hot disc have been used to characterize the coating mixture. The regression analysis has been used to study the effect of individual constituents and their binary, tertiary interactions on the properties. The obtained output of properties has been optimized using multi-response optimization.