检索结果-南通市图书馆

Synthesis and Structures of New Borophosphates (B_(1-X)M_X)PO_4 (M=Mn,Fe,Co,Ni,Cu) with Orthorhombic Low-Cristobalite Type

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1999年第8期10卷 707-708页

作者： Cheng Hua XU Shao Jie LU Gui Ying DENG Fa Li QIU (Chengdu Institute of Organic Chemistry. Chinese Academy of sciences, Chengdu 610041) dept. of Materials science Xiamen University Xiamen 361005 China dept. of Chemistry Xiamen University Xiamen 361005 China

The first reported (B1-xMX)PO4 (M = Mn, Fe, Co, Ni, Cu) compounds were synthesized by high temperature solid state methods and the structures refined from X-ray powder data. The transition metal substitutions on the boron site stabilized the structure to the orthorhombic low-cristobalite type with average volumes per tetrahedral unit 30% larger than that in BPO4 and novel catalytic properties are expected. The magnetic data indicate the 3+ valences for the metals.

关键词： Transition-metal borophosphate,synthesis,structure magnetic property

Packing Densities and Glass Forming Ability of Alloys

在线全文

学校读者我要写书评

暂无评论

Journal of Materials science & Technology 1996年第4期12卷 299-302页

作者： Jiang, Q Xu, XY Niu, HJ Lu, XX dept. of Materials science and Engineering Jilin University of Technology Changchun 130025 China

The random closed packing fraction of hard balls of three different sizes were measured by use of the Archimedes method. This packing fraction increases as the kind of balls with different sizes increases. The packing fraction is related to the mixing entropy of an ideal solution in respect to the holes among the hard balls. The composition zone of La-Al-Ni amorphous alloy made by cooling the alloy melt with a cooling rate of 90 Ks(-1) is located at same zone of the largest values of packing fraction and mixing entropy of hard balls in the ternary system, where the proportion of atom sizes of La, Al and Ni is similar to that of hard balls. The packing fraction and the mixing entropy are qualitatively considered as one of the criteria of the glass forming ability of alloys.

关键词： Amorphous materials

Unfiltered Diesel Engine Exhaust Treatment by Discharge Plasma: Effect of Soot Oxidation

在线全文

学校读者我要写书评

暂无评论

Plasma science and Technology 2004年第5期6卷 2475-2480页

作者： B.S.Rajanikanth Subhankar Das A.D.Srinivasan dept. of High Voltage Engineering Indian Institute of Science Bangalore 560012 IndiaDept. of High Voltage Engineering Indian Institute of Science Bangalore 560012 IndiaDept. of High Voltage Engineering Indian Institute of Science Bangalore 560012 India

A cascaded system of electrical discharges (Non-thermal plasma), catalyst andadsorption process was investigated for the removal of oxides of nitrogen (NO_x) and carbonmonoxide (CO) from a Diesel engine raw exhaust. The three processes were separately studied first,and then the cascaded processes, namely plasma-catalyst and plasma-adsorbent, were investigated. Inthis paper main emphasis was laid on the effect of carbonaceous soot oxidation on the plasmatreatment process. While the cascaded plasma-catalyst process exhibits a higher CO removal, thecascaded plasma-adsorbent process exhibits a higher NO_x removal. The experiments were conductedunder no-load. The plasma and adsorbent reactors were kept at room temperature throughout theexperiment while the catalyst reactor was kept at 200℃ / 300℃.

关键词： discharge plasma diesel engine exhaust catalyst adsorbent non-thermalplasma

Effects of Nitrogen Doping on Microstructure and Photocatalytic Activity of Nanocrystalline TiO_2 Powders

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials science) 2007年第3期22卷 457-461页

作者：杨志远 dept. of Chemistry and Chemical Engineering Xi’an University of Science and Technology

Nitrogen-doped TiO2 nanocrystalline powders were prepared by hydrolysis of tetrachloride titanium （TiCl4） in a mixed solution of ethanol and ammonium nitrate （NH4NO3） at ambient temperature and atmosphere followed by calcination at 400 ℃ for 2 h in air. FTIR spectra demonstrate that amine group in original gel is eliminated by calcination, and the TiO2 powder is liable to absorb water onto its surface and into its capillary pore. XRD and SEM results show that the average size of nanocrystalline TiO2 particles is no more than 60 nm and with increasing the calcination temperature, the size of particles increases. XPS studies indicate the nitrogen atom enters into the TiO2 lattice and occupies the position of oxygen atom. The nitrogen doping not only depresses the grain growth of TiO2 particles, but also reduces the phase transformation temperature of anatase to futile. The photocatalytic activity of the nitrogen-doped TiO2 powders has been evaluated by experiments of photocatalytic degradation aqueous methylene blue.

关键词： titanium oxide nitrogen doping photocatalytic activity nanocrystalline methylene blue

Allelopathic effect of Acorus tatarinowii upon algae

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental sciences 2001年第4期13卷 481-484页

作者： He, C.-q. Wang, C.-k. dept. of Environmental science/Eng. Shanghai University Shanghai 200072 China

Besides competing with algae for light and mineral nutrients (i. e. N, P, etc.), the root system of Acorus tatarinowii excretes some chemical substances, which injure and eliminate alga cells, to inhibit the growth of the algae. When the algae cells were treated in 'A. tatarinowii water', some of the chlorophyll a were destroyed and the photosynthetic rate of algae decreased markedly and the ability of alga cells to deoxidize triphenyltetrazolium chloride (TTC) reduced greatly. Then alga cells turned from bright red to bluish green under fluorescence microscope. These showed that the allelopathic effects of A. tatarinowii on algae were obvious and planting A. tatarinowii can control some green algae. The experiment on the extractions of the secretions of the root system showed that the inhibitory effect had a concentration effect. If the concentration of the root secretion was below 30 μl/disc, the inhibitory rate was negative; if it was over 45 μl/disc, the inhibitory rate was positive. This proved that the influence of the root secretion on the same acceptor was a kind of concentration effect. When the concentration of the root secretion was low, it promoted the growth of algae; when the concentration reached a definite threshold value, it restrained the growth of algae. In present case, the threshold value was between 30 μl/disc and 45 μl/disc.

关键词： Algae Cells Chlorophyll Concentration (process) Deoxidants Photosynthesis

Computer simulation for the effect of coherent strain on the precipitation progress of binary alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2007年第5期14卷 634-640页

作者：卢艳丽陈铮王永欣 dept. of Materials science and Engineering Northwestern Polytechnical University

Based on the microscopic elasticity theory and microscopic diffusion equation, the precipitation progress of the binary alloys including coherent strain energy was studied. The results show that coherent strain has obvious effect on the coherent two-phase morphology and precipitation mechanism. With the increase of coherent strain energy, the particles shape changes from the randomly distributed equiaxed particels to elliptical precipitate shapes,their arrangement orientation increases; in the late stage of precipitation, the particle arrangement presents obvious directionality along the [10]and[01]directions, and the precipitation mechanism of alloy changes from typical spinodal decomposition mechanism to the mixture process which possesses the characteristics of both non-classical nucleation growth and spinodal decomposition mechanisms.

关键词： binary alloy coherent strain precipitation progress computer simulation

Neural Nets:Another Paradigm for Decision Support

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 1995年第2期6卷 2-8页

作者： Feng Shan (dept. of ACE, Huazhong University of science and Technology, Wuhan 430074, China) dept. of ACE Huazhong University of Science and Technology Wuhan 430074 China

The paper presents an important aspect of Neural Nets application, i. e., their usefulness for decision support. The essential feature of the neural net approach to decision making is that it is a black-box approach, which means one does not try to model the underlying processes, but only looks for a tuning of the parameters of the neural net such that the black-box mimics the sensible behavior. Through the existing widespread applications in industry, business and science, the paper emphasizes their common property as a paradigm for decision support.

关键词： Neural network Neural-net controller Decision support Industrial applications.

Modeling and simulations of orbital capture with space tether-net system

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2009年第2期16卷 172-178页

作者：翟光仇越梁斌李成 dept. of Control science and Engineering Harbin Institute of Technology

A new flexible tether-net space robotic system used to capture space debris is presented in this paper. With a mass point assumption, a dynamic model of the tether-net system was established in orbital frame by applying Lagrange Equations. In order to investigate the net in-plane trajectories after being cast, the non-controlled R-bar and V-bar captures were simulated with ignoring the out-of-plane libration, and the effect of in-plane libration on the trajectories of the capture net was demonstrated by simulation results. With an effort to damp the in-plane libration, the control scheme based on tether tension was investigated, then an integrated control scheme was proposed by introducing thrusters into the system, and the nonlinear close-loop dynamics was linearised by feedforward strategy. Simulation results show that the feedforward controller is effective for in-plane libration damping and enables the capture net to track an expected trajectory.

关键词： tether-net system orbital caDture modeling simulation feedforeward control

Description and verification of switched control systems

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2003年第4期10卷 397-402页

作者：贺风华姚郁赵霞张猛 dept. of Control science and Engineering Harbin Institute of Technology

A modeling framework has been constructed using the theory of hybrid control systems for the switched control systems (SCS) and it can be more effectively used to describe the behavior of the systems and to more easily realize the simulation of the closed loop SCS under the MATLAB environment. On the other hand, a hybrid automaton model is established to analyze and verify the switched control systems. The proposed method is illustrated by an example of switched inverted pendulum control system.

关键词： hybrid systems switched control systems hybrid automaton