New approach for robust multi-objective optimization of turning parameters using probabilistic genetic algorithm

Limited by techniques, the process of remanufacturing exists masses of uncertainties which have a great impact on the remanufactured parts quality, how to achieve a higher quality of mechanical products by using limited remanufactured parts precision, has become one of the key issues of remanufacturing industry. Firstly, with a target to reduce uncertainties and improve the quality of automatic products, a method of tolerance grading allocation for remanufactured parts is proposed based on the uncertainty analysis of the remanufacturing assembly. The dimensional tolerances of the mechanical parts are divided into positive and negative two groups. We use selective assembly method to reduce assembling deviation. Then, the method is proven by mathematical formulas that the remanufactured parts variance can be expanded to two times, and the tolerances can be liberalized 40 % through tolerance grading allocation method. It is also the theoretical basis for improving the reuse radio and quantitatively describing the tolerance liberalization in this paper. Finally, feasibility research on this method is studied from the angle of cost–benefit. Furthermore, a tolerance grading allocation example of remanufactured engine piston assembly in a power corporation shows the validity and practicality of the proposed method.     

Effect of tip shape in the design of long distance electrostatic force microscopy

In this paper, it is shown that the tip as well as the cantilever (both conducting) act on the electrostatic force. The experimental results on force versus distance agree with the simulations derived from the Equivalent Charge Model. These simulations allow to determine the influence of geometry of the tip and bending of cantilever on the force exerting on the sensor. So, we predict the tip design and operating conditions (detection mode) to achieve the best resolution, particularly in long distance tip-sample in Electrostatic Force Microscopy.     

ZnO-nanorod arrays for solar cells with extremely thin sulfidic absorber

Solar cells with an extremely thin sulfidic absorber have been prepared by spray ion layer gas reaction (ILGAR) of In₂S₃ on ZnO-nanorod arrays. As transparent hole conductor, CuSCN was deposited on the coated ZnO nanorods by impregnation. Surface photovoltage spectroscopy was applied to characterize states contributing to excess carrier generation and charge separation. The charge-selective contact is formed at the In₂S₃/CuSCN interface region the states of which also contribute significantly to the photocurrent. The influence of annealing temperature and annealing time of the In₂S₃/CuSCN contact region on the open-circuit potential (V_OC), short-circuit current (I_SC) and fill factor (FF) was studied in detail. For solar cells based on ZnO-nanorod arrays (rod length 1.5 μm), efficiency of 2.8% is obtained at AM1.5.     

Optimization of solvent-free mechanochemical synthesis of Co/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts using low- and high-energy processes

In this work, alumina-supported cobalt (Co/Al₂O₃) catalysts were prepared using new solvent-free mechanochemical synthesis methods: low-energy vibratory ball milling (Fritsch, Pulverisette 0) and high-energy planetary ball milling (Retsch, PM 100). γ-Al₂O₃ supports and Co/Al₂O₃ catalysts after mechanochemical treatments were characterized using a combination of techniques. The study of solid particles revealed the abrasion and fragmentation phenomena of porous γ-Al₂O₃ particles and pore filling under milling. Functional cobalt particles introduced by the mechanochemical synthesis were observed to be preferentially localized on the outer surface of the alumina supports. High Fischer–Tropsch reaction rates were obtained with the catalysts prepared by optimized mechanochemical synthesis conditions. The enhanced catalytic performance can be attributed to the relatively high dispersion of cobalt and the absence of inert cobalt aluminates which are usually present in the catalysts synthesized by the conventional impregnation.     

Ab-initio study of magnetic,electronic and optical properties of ZnSe doped-transition metals

The full potential linear augmented plane wave (FPLAPW) based on density-functional theory (DFT) is employed to study the electronic, magnetic and optical properties of some transition metals doped ZnSe. Calculations are carried out by varying the doped atoms. Five 3d transition elements were used as a dopant: Cr, Mn, Fe, Co and Cu in order to induce spin polarization. Our results show that, Mn and Cu-doped ZnSe could be used in spintronic devices only if additional dopants are introduced; on the contrary, transition elements showing delocalized quality such as Cr, Fe and Co doped ZnSe might be promising candidates for application in spintronics. In addition, the three materials (CrZnSe, FeZnSe and CoZnSe) are half-metallic and ferromagnetic with an important magnetic moment ranging from 3 μ_B to 4 μ_B. Furthermore, we have computed optical properties of pure ZnSe, CrZnSe, FeZnSe and CoZnSe, and found a pronounced peak occurring at low energies in all the optical curves due to TM impurity and a low difference between doped and undoped compounds for higher energies.     

Optical and nuclear characterization of Xe-induced nanoporosity in SiO2

We performed RBS, infrared (IR) and C-V measurements in order to follow the evolution of Xe, bubbles/cavities and other defects (with a focus on NBOHC: non-bridging oxygen hole center) and dielectric constant (k), in high dose Xe implantation in SiO₂. As-implanted sample provides the lowest value of k which increases with post thermal annealing. In the meantime, the concentration of negatively charged defects decreases with annealing while Xe out-diffuses after annealing at 1100 °C leaving Xe free cavities in the sample. By combining these results one can determine the contribution of nanoporosity in dielectric constant evolution.     

A computational strategy for the localization and fracture of laminated composites. part 2. life prediction by mesoscale modeling for composite structures

The one-dimensional study presented in Part 1 of this paper is extended to the case of a two-dimensional layer laminate composite T300/914 subjected to a static bi-tension and shear. The regularization of this problem is due to the use of evolutionary models with delay effect where the velocity of damage is limited. The size of the localization area in the plane of the layers is related to the characteristic time of the model with delay and the loading rate. The work shows that the use of mesomodeling coupled with models of time delay damage evolution has identified the general localization area and has correctly predicted the time of fracture.     

Effects of experimental ternary cements on fresh and hardened properties of self-compacting concretes

Self-compacting concrete (SCC) is a concrete that flows alone under its dead weight and consolidates itself without any additional compaction and without segregation. As an integral part of a SCC, self-compacting mortars (SCMs) may serve as a basis for the mix design of concrete since the measurement of the rheological and viscosity properties of SCC is often impractical due to the need for complex equipment. This paper discusses the properties of SCM and SCC with mineral additions. ordinary Portland cement (OPC), natural pozzolana (PZ), and marble powder (MP) are used in ternary cementitious blends system following the cement substitution with PZ and MP in ratio 1/3. Within the framework of this experimental study, a total of 12 SCM and 6 SCC were prepared having a constant w/b ratio of 0.40. The fresh properties of the SCM were tested for mini-slump flow diameter, mini-V-funnel flow time, and viscosity measurement. Slumps flow test, L-box, J-ring, V-funnel flow time, and sieve stability were measured for SCC. Moreover, the development in the compressive strength was determined at 3, 7, 28, 56, and 90 days. Test results have shown that using ternary blends improved the fresh properties of the mixtures. The combination of natural pozzolana and marble powder increase the slump flow test up to 826 mm for the mixture prepared with 10% of mineral additions. Moreover, the use of mineral addition reduced the time flow to 4.27 s for SCC with 20% mineral addition, thus reducing the viscosity of all mixtures. Addition of MP increases the capacity of the passage through the plates between 88.75 and 93.50% for SCC with 7.5 and 15% of MP, respectively. The ternary system (PZ and MP) improve the sieve stability with the value for 4.07% of SCC with 50% of substitution compared for SSC without additions. The compressive strength of SCC at 90 days with 40% of PZ and MP was similar to that of OPC.     

脉动流条件下气体对旋流分离特性的影响

在原有旋流技术研究实验装置基础上, 增加一套脉动信号发生系统, 开展了脉动流条件下气体对水力旋流器分离特性影响的实验研究。研究结果表明: (1) 在一定条件下, 脉动流对提高水力旋流器的分离效率是有利的; (2) 在雷诺数Re=17 000、旋数S=9、脉动幅值比RQ=4%的条件下, 气液比Rgl=1左右时溢流颗粒相对净化率达到最大; (3) 在脉动流条件下, 气体的存在对水力旋流器分离效果的影响相对于稳定流要弱一些; (4) 随着含气量的上升, 流量脉动幅值增加比逐渐加大, 其变化趋势大体呈抛物线形。