排序方式: 共有34条查询结果,搜索用时 15 毫秒
1.
Center of gravity(COG) is an important parameter of projectiles and rockets, for which supporting reaction method(or support reaction method) is an important COG measurement method. Based on this supporting reaction method a novel design method is proposed to determine the key design parameters of the COG measurement system. The method can quantitatively analyze the influence of the design parameters on the COG accuracy, in the measurement system designed with supporting reaction method. Using the principle of static balance, the error propagation theory, and the system accuracy analysis method, the equal-range required sensor precision(RSP) surface and non-equal-range required sensor pair precision(RSPP) adapted surface are adopted. The influence of random errors(like sensor accuracy and distance calibration accuracy) is analyzed. The selection strategy of equal-range and non-equal-range sensors is chosen, and then the recommended calibration accuracy values are obtained. For the quality detection accuracy of ±0.6 kg and the axial COG detection accuracy of ±1.5 mm, the RSP surface is drawn by the proposed method, and the force sensor with ±0.23 kg detection accuracy is selected. The experimental verification meets the accuracy requirements and verifies the effectiveness of the proposed design method for the system parameters of the COG measurement equipment. 相似文献
2.
采用反应合成法制备Ag-CeO2复合材料,研究了Ag-CeO2复合材料的物相,在大塑性变形加工条件下的组织均匀化过程,以及Ag-CeO2复合材料的显微组织和物理性能的演变.XRD、SEM及能谱分析结果表明:通过反应合成法可以在Ag基体中合成尺寸细小的Ag-CeO2复合材料,其显微组织为Ag基体中分布着细小CeO2颗粒的团聚物. 经过累积大塑性变形加工能够对Ag-CeO2复合材料的显微组织起到均匀化和弥散化作用.Ag-CeO2复合材料的抗拉强度、电阻率等随真应变的增加而降低,延伸率随真应变的增加而提高. 相似文献
3.
This paper presents an overview of instrumentation and control (I&C) systems of a pressurized water reactor (PWR) type nuclear power plant (NPP) in Korea. Yonggwang unit 3, which was constructed as a basis model for a Korea standard nuclear power plant (KSNP), is selected as an example for the presentation. This overview is derived from analyzing the I&C systems based on a top-down approach. The I&C systems consist of 30 systems. The 183 I&C cabinets are also analyzed and mapped to the systems. The overview is focused on an interface between the systems and the cabinets. This information will be used to understand the implementation of the I&C systems and to group the systems for an upgrade. 相似文献
4.
本文采用对称多束会聚柬电子衍射图确定了一种尺度为数10nm至1μm的显微沉积相的晶体结构,指出会聚束衍射。尤其是对称多柬会聚束衍射图,是确定晶体材料中显微相结构的极其有用的方法。 相似文献
5.
菜籽肽抗氧化活性的研究 总被引:7,自引:0,他引:7
用分光光度法测定大鼠红细胞溶血程度,用丙二醛(MDA)试剂盒测定MDA。结果显示,通过腹膜注射菜籽肽,可以使小鼠血清中MDA含量显著减少。高剂量组[100 mg/(kg.d)]与对照组相比,MDA的降低达到极显著水平(P<0.01)。离体实验结果显示,菜籽肽粗品及各级分对体外温育和H2O2诱导的小鼠肝组织匀浆MDA生成有较强的抑制作用,其中粗品RSP-R和级分RSP-1的作用最好,且有量效关系,而对Fe2 诱导的MDA生成的抑制作用稍差。另外,RSP-R还可抑制大鼠红细胞氧化溶血程度。以上结果表明,菜籽肽在体内外均具有明显的抗氧化作用。 相似文献
6.
7.
Nicholas T. Karonis Kirk L. Duffin Caesar E. Ordoñez Bela Erdelyi Thomas D. Uram Eric C. Olson George Coutrakon Michael E. Papka 《Journal of Parallel and Distributed Computing》2013
Proton computed tomography (pCT) is an imaging modality that has been in development to support targeted dose delivery in proton therapy. It aims to accurately map the distribution of relative stopping power. Because protons traverse material media in non-linear paths, pCT requires individual proton processing. Image reconstruction then becomes a time-consuming process. Clinical-use scenarios that require images from billions of protons in less than ten or fifteen minutes have motivated us to use distributed and hardware-accelerated computing methods to achieve fast image reconstruction. Combined use of MPI and GPUs demonstrates that clinically viable image reconstruction is possible. On a 60-node CPU/GPU computer cluster, we achieved efficient strong and weak scaling when reconstructing images from two billion histories in under seven minutes. This represents a significant improvement over the previous state-of-the-art in pCT, which took almost seventy minutes to reconstruct an image from 131 million histories on a single-CPU, single-GPU computer. 相似文献
8.
Thadikamala Sathish Reddy Shetty Prakasham 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(1):50-58
BACKGROUND: Owing to the importance of glutaminase in biotech product production, its production with isolated Bacillus subtilis RSP‐GLU (MTCC 9727) was investigated. Fermentation factors play an important role in product enhancement. Hence, glutaminase production was optimized using an artificial neural network (ANN) coupled genetic algorithm (GA). RESULTS: A ‘6–12–1’ topology ANN was constructed to identify the nonlinear relationship between fermentation factors and enzyme yield. ANN‐predicted values were optimized for glutaminase production using a GA. The overall mean absolute predictive error (MAPE) and the mean square errors (MSE) were observed to be 0.00125 and 1.77 and 0.002 and 3.06 for training and testing, respectively. The goodness of neural network prediction (coefficient of R2) was found to be 0.996. The maximum interactive impact on glutaminase production was noted with rpm versus medium volume. The use of ANN–GA hybrid methodology resulted in a significant improvement (47%) in glutaminase yield. CONCLUSION: Five different optimum fermentation conditions out of 500 revealed maximum enzyme production. Glutaminase enzyme production in this Bacillus subtilis RSP‐GLU is strongly influenced by aeration of the fermentation. A hybrid ANN‐GA effectively identifies the different fermentation conditions for optimum production of enzyme in a given large set of conditions. Copyright © 2009 Society of Chemical Industry 相似文献
9.
The digitalized Instrumentation and Control (I&C) system of Nuclear power plants can provide more powerful overall operation capability, and user friendly man-machine interface. The operator can obtain more information through digital I&C system. However, while I&C system being digitalized, three issues are encountered: (1) software common-cause failure, (2) the interaction failure between operator and digital instrumentation and control system interface, and (3) the non-detectability of software failure. These failures might defeat defense echelons, and make the Diversity and Defense-in-Depth (D3) analysis be more difficult. This work developed an integrated methodology to evaluate nuclear power plant safety effect by interactions between operator and digital I&C system, and then propose improvement recommendations. This integrated methodology includes component-level software fault tree, system-level sequence-tree method and nuclear power plant computer simulation analysis. Software fault tree can clarify the software failure structure in digital I&C systems. Sequence-tree method can identify the interaction process and relationship among operator and I&C systems in each D3 echelon in a design basis event. Nuclear power plant computer simulation analysis method can further analyze the available backup facilities and allowable manual action duration for the operator when the digital I&C fail to function. Applying this methodology to evaluate the performance of digital nuclear power plant D3 design, could promote the nuclear power plant operation safety. The operator can then trust the nuclear power plant than before, when operating the highly automatic digital I&C facilities. 相似文献
10.
Abstract Five floors of a 20-year old 6-story office building were investigated using an integrated step-by-step investigation strategy. This involved a walkthrough inspection, an occupant questionnaire, and targeted environmental monitoring of indoor air quality and comfort parameters. The initial questionnaire survey revealed a high occurrence of building-related symptoms. The walkthrough inspection and environmental monitoring identified deposits of surface dust (indoor surface pollution – ISP) on carpets and hard surfaces, and elevated levels of carbon dioxide and respirable suspended particulate matter (RSP) throughout the building. An intervention study (blinded to the occupants) was targeted at reducing ISP levels by replacing normal carpet cleaning practices with higher performance vacuum cleaners and improved cleaning practices. The intervention reduced ISP levels and significantly lowered RSP concentrations by approx. 80% from initial values and against control floors. A follow-up SBS questionnaire revealed significant reductions in all but two of the symptoms. The most significant reductions occurred with symptoms of eye irritation, throat irritation, dry unproductive cough, and nose irritation. The study showed that in older buildings with poor ventilation, a build-up of ISP, and elevated RSP levels, using higher performance carpet cleaning practices can reduce RSP to acceptable levels and can reduce SBS symptoms. 相似文献