检索结果-南通市图书馆

Acta Metallurgica Sinica(English Letters) 1992年第2期5卷 141-144页

作者： XIA Lifang MA Xinxin harbin institute of technology,harbin,China harbin Inst of technology Harbin China

This paper deals with the cause of intergranular fracture occurred in the retained austenitic region in plasma carburized *** results show that the presence of retained austenite, which has a good effect on the impact toughness,has no relation to this ***- sis by Auger electron spectroscopy shows that the impurities S and P segregate at the grain boundaries is the main reason of the intergranular embrittlement in carburized layer. However,the segregation of P and S can be removed by reheating and quenching treatment.

关键词： plasma carburizing carburizing embrittlement impurity segregation

SIMULATION STUDY OF GENERALIZED MINIMUM VARIANCE CONTROL FOR AN EXTRACTION TURBINE

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2003年第4期16卷 424-427,444页

作者： Shi XiaopingSimulation Center,harbin institute of technology,harbin 150001, China Simulation Center Harbin Institute of Technology Harbin 150001 China

In an extraction turbine, pressure of the extracted steam and rotate speed of the rotor are two important controlled quantities. The traditional linear state feedback control method is not perfect enough to control the two quantities accurately because of existence of nonlinearity and coupling. A generalized minimum variance control method is studied for an extraction turbine. Firstly, a nonlinear mathematical model of the control system about the two quantities is transformed into a linear system with two white noises. Secondly, a generalized minimum variance control law is applied to the system. A comparative simulation is done. The simulation results indicate that precision and dynamic quality of the regulating system under the new control law are both better than those under the state feedback control law.

关键词： Extraction turbine Rotate speed Generalized minimum variance control Simulation

IN-SITU OBSERVATION OF THERMAL FATIGUE CRACK GROWTH IN STEEL 3Cr2W8V

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1993年第3期6卷 191-192页

作者： LIU Jianhong HE Shiyu YAO Mei harbin institute of technology,harbin,China lecturer,Depatment of Metallic Materials,harbin institute of technology,harbin 150006,China harbin Inst of technology Harbin China

The growing process of thermal fatigue cracking,in steel 3Cr2WSV was observed under desk SEM fitted with sell-made minisized device for thermal faligue *** the growing of thermal fatigue crack,the main crack tip reveals to blunt firstly,and some holes and uncontinuous microcraeks occur in front of *** growth is developed by bridging of main crack together with holes and microcracks.

关键词： steel 3Cr2W8V thermal fatigue crack growth in-situ observation

SYNTHESIS OF Ni-Mo ALLOYS BY MECHANICAL ALLOYING

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1993年第12期6卷 437-441页

作者： LIANG Guoxian WANG Erde HUO Wencan harbin institute of technology,harbin,China Post Box 435,harbin institute of technology,harbin 150006,China harbin Inst of technology Harbin China

Ni_(100-x)Mo_x(x=20,30,38)alloys have been synthesized by mechanical *** structure evolution of powders in mechanical alloying process has been monitored by X-ray diffraction,scanning electron microscopy and transmission electron microscopy *** results show that the Ni_(62)Mo_(38)sample becomes partially amorphous after high energy ball milling,while the Ni_(80)Mo_(20)and Ni_(70)Mo_(30)become non-equilibrium nanocrystals.

关键词： mechanical alloying Ni-Mo alloy amorphization nano-crystal

Autonomous control of multi-fingered hand

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第5期16卷 531-537页

作者： JIANG Li and LIU Hong (Robotics Research institute, harbin institute of technology, harbin 150001, China) Robotics Research institute Harbin Institute of Technology Harbin 150001 China

This paper describes a novel autonomous control strategy of multi- fingered hand based on a modular control system of dexterous manipulation. A simple proportional-integral-derivative(PID) position control with friction compensation, which requires few friction parameters, is used to realize accurate and smooth trajectory tracking in pregrasp phase. In grasp and manipulation phases, an event-driven switcher is adopted to determine the switching between unconstrained position control and constrained torque control, and an improved explicit integral force control strategy is implemented to realize simultaneously stable contact transition and accurate force tracking. Experimental results have verified the effectiveness of the proposed autonomous control strategy of multi-fingered hand.

关键词： multi-fingered hand autonomous control position control impact control.

Three-dimensional configurations of organic/inorganic hybrid nanostructural blocks (I).A quantum mechanical investigation for ladder-like structure of vinylsilsesquioxane

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2004年第5期47卷 388-395页

作者： ZHANG Xingwen1,2, HU Lijiang1, HUANG Yudong1, SUN Dezhi2 & SUN Yi3 1. Department of Applied Chemistry,harbin institute of technology, HUANG Yudong, harbin 150001, China 2. Department of Environmental Engineering, harbin institute of technology, harbin 150001, China 3. Department of Experimental Mechanics,harbin institute of technology, harbin 150001, China Dept. of Applied Chem. Harbin Inst. of Technol. Harbin 150001 China Dept. of Environ. Eng. Harbin Inst. of Technol. Harbin 150001 China Dept. of Experimental Mech. Harbin Inst. of Technol. Harbin 150001 China

The organic/inorganic hybrid nanostructural vinylsilsesquioxanes (VSSO) were prepared from the hydrolytic condensation of vinyltrimethoxysilane (VMS). The proposed formu- las of VSSO were assigned with standard spectroscopic techniques, FTIR, NMR (1H, C and 13 29Si) and MALDI-TOF MS, and a generic formula of the SSO, Tn(OH)x(OR’)y(x, y = 0, 1, 2…; n = 1, 2…; T = RSiO1.5 ?(x+y)/2n). Geometric parameters (Si-O and Si-C bond lengths, Si-O-Si and O-Si-O bond angles) and total energies of the multi-structures of VSSO were calculated by a quantum mechanical investigation and molecular symmetries. According to the results of the calculation, most molecules had stabler ladder structures than the cage isomers, therefore, the most probably reasonable and optimum structure of the VSSO system was the ladder type.

关键词： vinyltrimethoxysilane (VMS), silsesquioxanes (SSO), sol-gel process, quantum mechanical calculation, MNDO.

Mesh-dependence of Material with Softening Behavior

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2010年第1期23卷 46-53页

作者： Fu Li,Du Xingwen Center for Composite Materials,harbin institute of technology,harbin 150001,China Center for Composite Materials Harbin Institute of Technology Harbin 150001 China

The issue of mesh-dependence emerges when the conventional continuum damage model is applied to handling the softening behavior. In order to circumvent the mesh-dependence, the non-local theory is introduced into the conventional damage model and the finite element formulas are derived for two-dimensional gradient-enhanced damage model. A new element is proposed in which the basic unknown quantities are displacement, non-local equivalent strain and the gradient of non-local equivalent strain. The element and constitutive equation proposed in this article are added to the finite element software ABAQUS through user subroutine UEL. Numerical results show that the gradient-enhanced damage model can eliminate the mesh-dependence and is effective for dealing with the issue of softening behavior.

关键词： non-local theory gradient dependence softening behavior mesh-dependence Hermitian element finite element method

TENSILE FRACURE IN AN Al-Li ALLOY 8090

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 1995年第2期5卷 106-108页

作者： Jiang, Daming Wang,Yinong Hong, Bande Lei, Tingquan(harbin institute of technology, harbin 150080)Sun Fenglian(harbin University of Science and technology, harbin 150001) harbin Inst of technology Harbin China

ＴＥＮＳＩＬＥＦＲＡＣＵＲＥＩＮＡＮＡｌ－ＬｉＡＬＬＯＹ８０９０￥Ｊｉａｎｇ，Ｄａｍｉｎｇ；Ｗａｎｇ，Ｙｉｎｏｎｇ；Ｈｏｎｇ，Ｂａｎｄｅ；Ｌｅｉ，Ｔｉｎｇｑｕａｎ（ＨａｒｂｉｎＩｎｓｔｉｔｕｔｅｏｆＴｅｃｈｎｏｌｏｇ... 详细信息

ＴＥＮＳＩＬＥＦＲＡＣＵＲＥＩＮＡＮＡｌ－ＬｉＡＬＬＯＹ８０９０￥Ｊｉａｎｇ，Ｄａｍｉｎｇ；Ｗａｎｇ，Ｙｉｎｏｎｇ；Ｈｏｎｇ，Ｂａｎｄｅ；Ｌｅｉ，Ｔｉｎｇｑｕａｎ（ＨａｒｂｉｎＩｎｓｔｉｔｕｔｅｏｆＴｅｃｈｎｏｌｏｇｙ，Ｈａｒｂｉｎ１５００８０）Ｓｕ...

关键词： Al-Li alloy tensile fracture dimple rupture cleavage

CORRELATION BETWEEN MICROSTRUCTURE AND STRESS CORROSION CRACKING SUSCEPTIBILITY OF 2091 ALLOY

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1992年第12期5卷 483-488页

作者： LJ Benshun harbin institute of technology,harbin,China CHEN Xiangping lianghan Petroleum institute,Wuhan,China harbin Inst of technology Harbin China

The stress corrosion cracking(SCC) susceptibility of an Al-Li-Cu-Mg-Zr alloy(2091), heat-treated under different regime,has been investigated hy means of tensile tests at slow strain *** microstructure has been examined with *** deformation characteristic has also been *** stress corrosion resistance of the alloy was revealed to be mainly affected by the covering rate of T_2-phase over grain boundaries and by the average distance between T_2-phase particles. SCC resistance can be obviously improved by predeforming the alloy at room temper- ature to reduce the precipitation of T_2-phase along grain boundaries.

关键词： AI-Li alloy stress corrosion microstructure pre-deformation