基于最小二乘法的执行器系统机械属性评价

分析了机械属性评价方法的优缺点,给出了气动执行器和电动执行器系统机械属性的主要评价因素,并列出了执行器系统评价因素数据获取的3个途径,提出了一种基于最小二乘法的执行器系统组合权重机械属性评价方法.首先运用信息熵理论和层次分析法(AHP,Analytic Hierarchy Process)理论,分别得到两种执行器系统的机械属性权重,然后运用最小二乘法求得执行器系统的组合权重,计算出执行器系统综合评价值,选出最优方案,最后运用具体实例进行了评价方法验证.结果表明,以特定工况下的气动和电动执行器系统为例,运用组合权重机械属性评价方法,得出气动执行器系统比电动执行器系统机械属性更好,符合现场工况;执行器系统的组合权重机械属性评价结果的标准偏差比信息熵和层次分析-模糊综合评价(AHP-FCE,AHP-Fuzzy Comprehensive Evaluation)的都小.

实体理论机制:婴儿关于物理世界的“机械模块”

“实体理论机制”(ToBy)是Leslie假设的婴儿对物理世界的客体和事件的机械属性进行计算加工的先天装置。它具有帮助婴儿理解能量之源、描述客体的机械属性并完成对客体的早期分类等功能。ToBy的提出是对核心领域发展观的深化,也对皮亚杰理论构成了一种挑战。

Microstructures and properties of PVD TiAlN coating deposited on cermets with different Ti(C,N)grain size

In the present work,TiAlN coatings were deposited on Ti(C,N)-based cermet substrates by physical vapor deposition method.Emphasis was focused on the influence of grain size of cermet substrates on the microstructure,growth behavior,mechanical properties,adhesion strength and wear behavior of the coatings.The results show that finer Ti(C,N)grain size leads to higher nucleation density and lower growth rate of coatings,indicating the crystallite size of the TiAlN coatings decreases with decreasing Ti(C,N)grain size.Nanoindentation tests show that the coatings deposited on cermets of the finest grain size exhibit the highest hardness(H),elastic modulus(E),H/E and H3/E2 of 34.5 GPa,433.2 GPa,0.080 and 0.22,respectively.The adhesion strength between coating and substrate is also enhanced with decreasing Ti(C,N)grain size by scratch test,which corresponds to the grain size and H/E and H3/E2 of the coating.Besides,the lower surface roughness and better mechanical properties of the coating deposited on finer grained cermet contribute to the better wear resistance of the coating.

Si_3N_4-doped Zr_(50)Al_(15)Ni_(10)Cu_(25) glassy alloy by mechanical alloying and sintering process

Zr50Al15Ni10Cu25 amorphous powder was synthesized by mechanical alloying. The effect of Si3N4 addition on the crystallization behavior of the alloy during sintering process was studied. Thermal stability of the powders was performed by differential scanning calorimetry （DSC）. The phase and microstructure of the powders and bulk specimens sintered were determined by X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. The results show that, introducing 0.05% （mass fraction） Si3N4 can enhance the crystallization activation energy of the ZZr50Al15Ni10Cu25 amorphous powders, which indicates that Si3N4 addition has hindrance effect on forming crystals from Zr50Al15Ni10Cu25amorphous powder. However, 0.10% Si3N4 results in the decrease of the crystallization activation energy, which makes its crystallization process easy to occur.

Safety and Quality Attributes of Sucuk-Like Product Made with Mechanically Deboned Broiler/Beef

In this study, sucuk-like products （SLP） has a great consumption in Turkey, which are produced with broiler or mixture of beef and broiler meat and after stuffing into artificial casings heat treatment is applied after rapid fermentation. Quality （color, pH, texture） and safety （2-thiobarbituric acid reactive substance （TBARS） value and biogenic amine） attributes of SLP made with broiler, mechanically deboned meat （MDM） of broiler chicken, mix of broiler chicken and beef, or mix of MDM of broiler chicken and MDM of beef were investigated, pH values of samples had similar range. Mechanically deboned meat containing samples have higher TBARS values than that of others. Samples made with MDM of broiler chicken have higher histamine, tyramine, putrescine and total biogenic amine concentrations than samples made with broiler chicken. There was no significant difference （P 〉 0.05） between total biogenic amine contents of fermented and non-fermented samples. Also, samples gave similar measured and calculated color values. Hardness, gumminess and chewiness values of samples made with MDM of broiler chicken were significantly higher （P 〈 0.05） than samples made with broiler chicken. It was observed that addition of mechanically deboned meat could result in loss of safety and quality attributes of sucuk-like products.

Pulse Electromagnetic Effect on Metal Melts

The aim of the work was the study of the effect of NEMP （nanosecond electromagnetic pulses） on steel properties. Steel treatment was performed under the workshop conditions. The mechanical properties and the microstructure of the experimental samples and samples prepared by usual way were analyzed. The treatment of metal melt with nanosecond electromagnetic pulses at the crystallization stage makes it possible to change mechanical properties of metal and its structure.

Preparation of Alumina Binder-Added PtSnNa/AlSBA-15 Catalyst for Propane Dehydrogenation

Abstract： The present article compares the propane dehydrogenation performance of alumina binder-added PtSnNa/ A1SBA-15 catalysts prepared via three different procedures in comparison with the performance of a binder-free PtSnNa/ AISBA-15 catalyst. All these catalysts have been investigated by reaction tests and some physico-chemical characterizations such as BET, H2 chemisorption, catalytic grain crushing strength, NHa-TPD and TPO analyses. Test results showed that the addition of alumina binder could enhance the mechanical strength of catalyst evidently. Moreover, the different preparation procedures not only modified the characteristics of both acid and metal functions but also affected the coke deposition on the catalysts. Among these catalysts studied, the catalyst prepared by impregnation followed by the agglomeration of alumi- na binder had exhibited the highest catalytic activity and stability compared with other catalyst samples undergoing different preparation procedures. The possible reason may be attributed to the highest metallic dispersion and the strong interactions among Pt, Sn and the support.

Low-temperature fusion fabrication of Li-Cu alloy anode with in situ formed 3D framework of inert LiCu_x nanowires for excellent Li storage performance

The commercialization of rechargeable Li metal batteries is hindered by dendrite growth and volumetric variation. Herein, we report a Li-rich dual-phase Li-Cu alloy with built-in 3 D conductive skeleton to replace conventional planar Li anode. The Li-Cu alloy is simply prepared by fusion of Li and Cu metals at a relatively low-temperature of 500 °C, followed by a cooling process where phase-segregation leads to metallic Li phase distributed in the network of LiCu_x solid solution phase. Different from the common Li alloy, the electrochemical alloying reaction between Li and Cu metals is not observed. Therefore, the lithiophilic LiCu_x nanowires guides conformal plating of Li and the porous framework provides superior dimensional stability for the anode. This unique ferroconcrete-like structure of Li-Cu alloy enables dendrite-free Li plating for an expanded cycling lifetime. Constructing a new type of Li alloy with in situ formed electrochemically inactive framework is a promising and easily scaled-up strategy toward practical application of Li metal anodes.

Effects of the laser surface treatment on the mechanical properties of CuZr-based bulk metallic glasses

Surfaces of three types of CuZr-based bulk metallic glasses （BMGs） were modified by laser surface treatment （LST）, and the influence of the treatment on structure and mechanical properties of these alloys was investigated. The phase structure of as-cast and laser-treated samples was characterized by XRD and the morphology of the alloys after fracture was examined by SEM. The compressive plasticity of treated Cu47.sZr47.sAI5 and Cu46.sZr47.sAlsCo~ BMGs can be improved from 0.5% to 2.0% and from 1.2% to 5.7% respectively compared with the as-cast ones, while （Cu0.55Zr0.40Ala05）99Er~ BMG shows insignificant change of plasticity. The improvement in plasticity is attributed to induced crystallization of B2 CuZr phase in the treated sur- face zone of selected metallic glasses.

Metallic glassy fibers

A review on the formation and unique physical and mechanical properties of metallic glassy fibers(MGFs)with the diameter ranging from micro to nano scales fabricated by a supercooled liquid extraction method(SLEM)is given.The SLEM method,through driving metallic glass rods in their supercooled liquid region via superplasticity,can fabricate MGFs with precisely designed and controlled size and properties,high structural uniformity and surface smoothness and extreme flexibility.The SLEM method is efficient and the MGFs can be continuously prepared by this method.A parameter f based on the thermal and rheological properties of MG-forming alloys is proposed to control the preparation and size of the fibers.We show that the novel MGFs with superior properties may attract intensive scientific interests and propel more engineering and functional applications.