Failure of a Fusion Welded Ball Joint as a Result of Modification in MnS Direction

A failure investigation was performed on a ball joint from an ATV front suspension system. The location of the fracture was the bearing ball/stud interface, which is a fusion-welded joint, and occurred after approximately 20 h of field-testing. The two parts are made out of carbon steel and were previously heat-treated. Many elongated MnS inclusions were found in the stud material, and these inclusions were parallel to the symmetry axis. Even though these inclusions were not significantly sized, their number was important. Macroscopic evidence showed that the joint failed in a ductile mode under centered tensile overload. Microscopic examination showed that MnS orientation changed in the fusion joint area. The inclusions had been redirected during the welding process and laid parallel to the fracture surface. This reorientation caused a significant decrease in the effective cross section of the joint and overload fracture occurred.     

人工环境与自然的融合——以克拉玛依市城南经济适用房为例

近年来,随着社会经济的发展,中低收入居民住房建设及生态保护成为城市建设的重点内容。而人工环境与自然的协调统一、相互融合,也一直被作为世界范围内社区环境营造所遵循的热点及难点。如何在保障中低收入居民住房条件基础上,将自然与人工社区环境相融合是该文研究的重点。该文试从生态环保、尊重自然、与自然环境相融合的角度出发,以克拉玛依市城南经济适用房项目为例,试探讨该理念在经济适用房建设中低成本、经济适用等方面的合理应用。     

基于优化神经网络的采集终端软件可靠性预测

采集终端软件的可靠性是评价软件系统生命周期的一个重要指标。针对多种神经网络和支持向量机等方法在软件系统可靠性评价中存在的参数优化困难、软件系统预测模型的低准确率问题,提出基于SAGFA-BPNN的建模方法。该方法采用PCA对实验数据降维处理,剔除影响模型准确率的冗余和干扰样本;在优化SA和GA的基础上,给出退火遗传融合优化算法(SAGFA),并发挥其全局寻优能力,以及BPNN非线性映射能力,提出SAGFA-BPNN网络,及基于它的建模方法,以提高训练速度、全局寻优能力及准确度。文章还应用该方法对采集终端软件的可靠性进行了预测,预测结果表明,该方法可以有效地提高模型的准确度。     

人白细胞介素12双亚基共表达pVAX1-IRES-hIL12载体的构建与表达

目的构建下游可以共表达人白细胞介素12(hIL12)双亚基的双顺反子真核表达载体pVAX1-IRES-hIL12。方法通过搭桥PCR获得人白细胞介素12P35及P40双亚基的融合基因P35-F2A-P40,插入DNA疫苗载体pVAX1-IRES的下游,瞬时转染293-T细胞,ELISA检测融合基因的表达。结果酶切鉴定和序列分析表明融合基因与设计完全一致,融合基因在体外细胞培养液检测中获得分泌表达。结论该载体的成功构建可以为肿瘤基因疫苗研制提供免疫增效载体。     

Degradation-oriented real-time power control of fuel cell hybrid vehicles under uncertain driving conditions

This work provides a real-time power allocation algorithm to address uncertain actual driving situations for fuel cell hybrid vehicles. To predict the vehicle speed under nondeterministic driving conditions, a fusion prediction model is developed based on the advantages of the Markov chain and neural network. The optimal power splitting decision in each receding horizon is then solved using the Pontryagin's minimum principle (PMP) method, considering fuel consumption, State of Charge (SOC), and performance degradation. A degradation model of electrochemical active surface area (ECSA) based on Pt catalyst dissolution was developed. Then the effect of the energy management algorithm on fuel cell degradation was evaluated using the degradation model. Compared with the two conventional real-time power splitting strategies, the approach suggested in this research can better reduce the fuel consumption and maintain the stability of battery SOC with a lower fluctuation while taking into account the degradation of the fuel cell.     

Neutron computed tomography of plasma facing components for fusion experiments

In nuclear fusion experiments, divertor plates are used to remove energy and particles from the plasma. These divertor plates can be made of water-cooled copper heat sinks covered by carbon fiber composite (CFC) protection tiles. During operation, surface temperatures in excess of 1000 °C are reached for typical heat loads of 10 MW/m². The large mismatch in the coefficients of thermal expansion for CFC and Cu causes high stresses and possibly bonding defects. Growing joint defects, which lead to unacceptable overheating of the protection tiles, are critical for the lifetime of the components.A prototype component was subjected to 10,000 cycles at 10 MW/m² to study the crack growth mechanism. Neutron computed tomography offers the possibility to analyze such structures on centimeter-sized samples non-destructively with a high spatial resolution. At the ANTARES neutron imaging facility of the FRM II reactor, the samples were loaded with a contrast agent and examined with neutron computed tomography.     

External Factors Affecting Fusion Energy Development

A number of external factors affecting the pace and direction of fusion energy development are reviewed and discussed. These include the changing electric utility marketplace environment, the availability of fossil fuels, competing power sources, and environmental issues.     

Al-Cr-O thin films as an efficient hydrogen barrier

Thin Al-Cr-O films are proposed as hydrogen permeation barriers. Layers of a few microns in thickness are able to suppress hydrogen permeability by a factor of 2000 to 3500 at temperatures of 700 °C, as has been found in our gas phase permeation experiments. We attribute this excellent efficiency to a dense layer morphology and the possible (pre)-formation of solid solutions in corundum-type structure. These films are deposited by pulsed arc evaporation in a batch-type production system at substrate temperatures of 550 °C.     

Multiple architecture system for wind speed prediction

A new approach based on multiple architecture system (MAS) for the prediction of wind speed is proposed. The motivation behind the proposed approach is to combine the complementary predictive powers of multiple models in order to improve the performance of the prediction process. The proposed MAS can be implemented by associating the predictions obtained from the different regression algorithms (MLR, MLP, RBF and SVM) making up the ensemble by three fusion strategies (simple, weighted and non-linear). The efficiency of the proposed approach has been assessed on a real data set recorded from seven locations in Algeria during a period of 10 years. The experimental results point out that the proposed MAS approach is capable of improving the precision of the wind speed prediction compared to the traditional prediction methods.     

Object Kinetic Monte Carlo calculations of irradiated Fe-Cr dilute alloys: The effect of the interaction radius between substitutional Cr and self-interstitial Fe

Object Kinetic Monte Carlo models allow for the study of the evolution of the damage created by irradiation to time scales that are comparable to those achieved experimentally. Therefore, the essential Object Kinetic Monte Carlo parameters can be validated through comparison with experiments. However, this validation is not trivial since a large number of parameters is necessary, including migration energies of point defects and their clusters, binding energies of point defects in clusters, as well as the interaction radii. This is particularly cumbersome when describing an alloy, such as the Fe-Cr system, which is of interest for fusion energy applications. In this work we describe an Object Kinetic Monte Carlo model for Fe-Cr alloys in the dilute limit. The parameters used in the model come either from density functional theory calculations or from empirical interatomic potentials. This model is used to reproduce isochronal resistivity recovery experiments of electron irradiated dilute Fe-Cr alloys performed by Abe and Kuramoto. The comparison between the calculated results and the experiments reveal that an important parameter is the capture radius between substitutional Cr and self-interstitial Fe atoms. A parametric study is presented on the effect of the capture radius on the simulated recovery curves.