Effect of Laser Power on the Cladding Temperature Field and the Heat Affected Zone

 Abstract: In this paper, H13 powder is cladded on P20 base during continuous CO2 laser, the influence of processing technologies such as the laser power is analyzed. The 3-D model of synchronous powder feeding is established under Gauss heat source, the simulation results are compared with the experimental data. The results show that the temperature field and the size of heat affected zone are affected by laser power. In the heat affected zone, experimental sizes are compared with simulative sizes, the average errors in width and in depth are 15% and 4.5%, respectively.     

IDENTIFICATION AND CHARACTERIZATION OF SOME OXIDIZING ENZYMES OF THE MC FARLIN CRANBERRY

SUMMARY– Enzyme extracts were prepared from acetone powders with and without phenol-binding agents such as polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) and buffered PVP. The acetone-PVP combination was found most effective in reducing the polyphenolic content of the enzyme extract. Highest specific activity was obtained by using a buffered PVP extract. The pH optimum of cranberry peroxidase activity was 6.0. Heat inactivation of cranberry peroxidase was determined to follow first order kinetics. There was 90% destruction at 70, 80, and 90°C requiring 9.40, 1.60, and 0.47 min of heat treatment, respectively. Activation energy for the thermal inactivation of cranberry peroxidase was observed to be 37.2 kcal/mole. Guaicol, o-phenylene diamine (OPDA), and pyrogallol were tested for their sensitivity to cranberry peroxidase with OPDA determined as most sensitive. The pH optimum for catalse activity was found to range from 7.5 to 9.2. Kinetics for the heat inactivation of cranberry catalase was observed not to be of the first order nor zero order. Approximately 50% of the catalase activity was inactivated after heating for 17, 1.8, and 0.6 min at temperatures of 50, 60, and 70°C, respectively. The pH optimum for cranberry polyphenolase activity was determined to be 7.0. Heat inactivation of cranberry poly-phenolase was found to follow first order kinetics. There was 90% destruction at 50, 60, and 70°C requiring 15.85, 7.05, and 1.37 min of heat treatment, respectively. The activation energy for the inactivation of cranberry polyphenolase was observed to be 27.7 kcal/mole.     

Physical-Chemical Characteristics of Partially Clarified Guava Juice and Concentrate

Partially clarified guava juice concentrate was prepared from single strength guava puree (5.5°Brix) by treatment with pectinase (2 hr at 50°C), extraction of juice with a rack-and-cloth press, and vacuum concentration to 23°Brix. The concentrate had the following characteristics: density, 1.10; pH, 3.16; total acids, 4.67%; ash, 1.51%; moisture, 72.4%; ascorbic acid, 867 mg%; viscosity, 4.4 cp; and CIE L* 39.2, CIE a* 10.33, CIE b* 27.11.     

用时域法和频时域法识别桥面移动车载

基于欧拉梁模型,本文利用时域法和频时域法由桥梁响应识别桥面移动车载并重点讨论了几个主要参数对识别结果的影响。这些参数包括模态数、采样频率、车速、响应测点位置和测点数等。结果表明：车桥试验室模型是成功的,用时域法和频时域法均能得到满意的识别结果,但以时域法实用性更强、精度更高,可以直接用于桥面移动车载识别的现场试验。     

提高酸乳中c9,t11- 共轭亚油酸含量的研究

本研究利用乳酸菌发酵法,添加合适的底物,在形成酸乳的同时提高乳中c9,t11- 共轭亚油酸,c9,t11-CLA的含量,筛选菌株的最佳配比条件,研究影响CLA 含量的因素,发现奶中影响酶促反应和菌株生长的营养成分均可以影响乳酸菌发酵中CLA 的产生。应用气相色谱检测出乳酸菌培养液中CLA 的其它异构体。     

Singular extremal control problem with time delay

In this article, the singular extremal control problem with time delay is studied from the viewpoint of the calculus of variation and matrix theory. Some sufficient conditions for the non-negativity of the second variation are obtained for an optimal control problem with a delayed state vector. The hypothesis of Hass is first assumed, and the total singular situation of Jacobson and Bell is also considered. A second-order necessary condition for optimality is also presented.     

An algorithm for function restoration using eigenvectors†

This paper presents an algorithm for the restoration of the characteristics of a function from a finite number of observed points. The algorithm uses the eigenvectors of the Gramian of the observed vectors and is based on the assumption that the function to be constructed can be represented by a specified form. Convergence of the algorithm is proved for the noiseless case. When noise is present, a bound for the error is obtained. For functions not representable in the assumed form, the algorithm can be used to test the non-representability of the function. A numerical example is given to illustrate the theoretical investigation.     

Influence of pH on colour and iron content of peptide fractions obtained from bovine Hb concentrate hydrolysates

The effect of pH on colour and iron content (Fe) of peptide fractions obtained from bovine haemoglobin concentrate (BHC) hydrolysates was studied. Four hydrolysates were obtained using three enzymes: Protex‐6‐L (P), Fungal–Protease–Concetrate (FC) and Flavourzyme (F). BHC and its hydrolysates (P, FC, P + F, FC + F) were fractioned at pH 4.5, 7.0 and 9.5. Solubility and Fe from different fractions were measured. Correlations between CIELAB colour parameters and Fe from different fractions were analysed. The colour from different fractions varied from red to yellow (a* and b* positives). Lightness values (L*) ranged from twenty‐four to seventy. FC4.5 and FC + F4.5 fractions were the clearest and yellow (higher L*, b*, h), while BHC9.5 and P + F9.5 fractions had the lowest values of L*, b* and h. There was an inverse linear relationship between b* and L* parameters and Fe from fractions. This relationship could be associated with the pH of extraction. As pH increases Fe significantly increases and lower b* and L* values were obtained.     

基于宏程序的电子对刀仪在加工中心的应用

分析对刀仪的结构和工作原理,设计对刀宏程序,实现自动对刀、自动设定或更新刀具的长度补偿值,并根据实际情况增加安全警报、状态保护功能.同时设计连接部分硬件.采用上述方案实现了电子对刀仪在加工中心上的安装和使用,提高了在加工中心进行刀具长度补偿的精度和效率;并节约了购买软件的成本.同时将该方案用于课程教学.增强了学生对数控机床辅助设备安装维修能力.