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A simple solution route to control synthesis of Fe_3O_4 nanomaterials at low temperature and their magnetic properties

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science china Chemistry 2009年第7期52卷 916-923页

作者： LIU Yi1,2, CHEN Yun1, ZENG YuPing2 & WANG ShiLong3 1 department of Chemistry and Chemical engineering, Zaozhuang University, Zaozhuang 277160, china 2 Shanghai institute of Ceramics, Chinese Academy of sciences, Shanghai 200050, china 3 School of Life science and technology, Tongji University, Shanghai 200092, china 1. department of Chemistry and Chemical engineering Zaozhuang University Zaozhuang 277160 China 2. Shanghai institute of Ceramics Chinese Academy of Sciences Shanghai 200050 China 3. School of Life science and technology Tongji University Shanghai 200092 China

A series of nanostructured iron compounds including cubic Fe3O4 and orthorhombic FeOOH were synthesized via a facile low temperature (in the range of 60-100℃) solution method. In the whole process, the interaction between FeCl2·4H2O and methenamine (C6H12N4) was carried out through a reflux device under different reaction conditions such as temperature, solvent, and duration. The samples were detected by XRD, TEM, SAED, physical property measurement system, and Mssbauer spectroscopy, separately. The experiments showed that magnetic mixture nanoparticles had flake and rod morphologies, and cubic Fe3O4 took on grain nanostructure. Magnetism measurements indicated that the saturated magnetization of the as-obtained magnetic mixture was lower than that of the cubic magnetite. Mssbauer spectroscopy testified the sample consisting of cubic magnetite rather than γ-Fe2O3. In addition, a possible growth mechanism of cubic magnetic nanoparticles under different conditions was discussed.

关键词： magnetic nanoparticles cubic Fe3O4 oxidation-coprecipitation method reflux magnetic properties at room temperature Mssbauer spectrum

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Research on Fracture Behavior of Film-substrate System

Research on Fracture Behavior of Film-substrate System

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第一届工程科学与力学中的计算方法国际会议

作者： Baoliang Liu and Xianshun Bi department of Mathematics and Mechanics heilongjiang institute of science and technology harbin 150027 china

＜正＞The last decade has seen enormous progress in the area of integrated circuits, microelectronic, and micro-machined devices. These engineering systems typically consist of dissimilar materials joined together on a substrate, i.e. the film-substrate composite system. Owing to the high performance demands of engineering devices, film technology profoundly affects the lifetime of materials. In filming process, the thermal stress exists due to the difference among the thermal expansion coefficients of the film and the substrate, which may result in cracking of the films. Thus, the reliability of these systems often depends on the fracture behavior of the films comprising the device and a good understanding of the possible failure mechanisms makes it possible to design more reliable devices. This study gives the problem of a crack in the film oriented perpendicular to the film-substrate interface with the crack tip fully within the film. Based on Beuth’s theory, three-dimensional model is simplified to plane strain problems, which obtains fracture mechanisms of a cracked film-substrate system by applying the boundary element method（BEM）. The method aptly resolves the problem involving stress concentration The results indicate: the stress intensity factor is affected by the different elastic mismatches and the thickness ratio of the film and the substrate, and it has remarkable increased with the decrease of the thickness ratio of the film and the substrate. The effect of the fracture behavior of film is negligible when the thickness ratio of the film and the substrate is more than 10. The conclusion has theoretical significance for researching fracture behavior of film-substrate system by experimental mental method. What’s more, this paper studies the special condition of the film-substrate system, which is the analysis of the fracture of the absence of any elastic mismatch between the film and the substrate, i.e. α=β=0, and revision of the formula of Xia and Hutchinso

关键词： film-substrate system crack stress intensity factor boundary element method

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Optimal Guidance Law Design for Reentry Vehicle Using Virtual Displacement Concept

Optimal Guidance Law Design for Reentry Vehicle Using Virtua...

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第二十六届中国控制会议

作者： Gao Changsheng,Jing Wuxing,Li Chaoyong department of Aerospace engineering,harbin institute of technology,harbin 150001,P.R.china

The new predictive guidance law for reentry vehicle is presented in this *** proposed approach is based on the fact that lateral forces are formed to a plane perpendicular to the reentry vehicle *** particular,the nominal ground location is defined as the ground location generated by the zero lift trajectory,the virtual displacement is defined as the small changes of the nominal ground location,this changes is caused by any instantaneous lateral force at the beginning of the *** optimal direction of the lateral force is searched by the solution to the optimal virtual displacement,in which case the virtual displacement is pointing to the target ground *** analytical solution to the reentry trajectory and the linear quadratic gauss（LQG）method are used in this guidance *** simulation results show that the effectiveness of proposed method.

关键词： Optimal reentry vehicle guidance law virtual displacement linear quadratic gauss

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Filippov Solutions on a Lipschitz Continuous Surface

Filippov Solutions on a Lipschitz Continuous Surface

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第二十七届中国控制会议

作者： Zheng Kai1,Shen Tielong2,Yao Yu1 1.department of control science and engineering,harbin institute of technology,harbin 150001,P.R.china2.department of Mechanical engineering,Sophia University,Tokyo,Japan

In this paper,the further discussion on Filippov solutions is *** criterions are proposed to determine the relation between system trajectories and an arbitrary Lipschitz continuous *** show that the set-valued vector field of Filippov’s differential inclusion and the cone property of the hypersurface play an important role in the *** the hypersurface is only Lipschitz continuous,we prove that there exists the trajectory sliding along the *** result allows us to construct the sliding mode control for more general sense,because the sliding surface can be designed Lipschitz continuous. Finally,we provide some numerical examples to illustrate our designs.

关键词： Filippov solutions Lipschitz hypersurface Contingent cone

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Vehicle State and Friction Force Estimation Using Nonlinear Observer Strategies

Vehicle State and Friction Force Estimation Using Nonlinear ...

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第二十七届中国控制会议

作者： Zhao Linhui 1,Liu Zhiyuan 1,Chen Hong 2 1.control science and engineering,harbin institute of technology,harbin 150001,P.R.china 2.control science and engineering,Jilin University,Changchun 130025,P.R.china

Approaches to estimate friction forces and vehicle states are presented in this ***,based on the dynamical equations of the wheels,the estimates of the longitudinal friction forces are achieved by means of sliding mode unknown input estimation ***,using the longitudinal friction forces estimated and the nonlinear relation between lateral and longitudinal friction force of the tire,a new nonlinear vehicle dynamic model is ***,based on this model,nonlinear observers for estimation of longitudinal and lateral velocities are modified and extended to work for different road surface conditions and in critical driving *** input-to-state stability results are *** friction forces and vehicle states estimated are compared to those of the simulator *** results show the effectiveness of the proposed approaches.

关键词： Friction force estimation Vehicle state estimation Sliding mode observer Nonlinear observer

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Construction and Characteristics of cDNA Library from Trichoderma harzianum Mycelium

Construction and Characteristics of cDNA Library from Tricho...

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第三届国际生物防治与生物技术研讨会

作者： LIU Pigang,YANG Qian,YANG Liming Dept.of Life science and engineering,harbin institute of technology,harbin, 150001 P R china

Trichoderma harzianum is commercially applied as biological control agents against fungal pathogens based on different mechanisms as the production of antifungal metabolites,competition for space and nutrients and *** achieve the genetic information on Trichoderma harzianum and to explore the novel genes for bio-control,a unidirectional cDNA library has been constructed from mycelium of *** *** titer of original library was 1.2x10pfu/ml and the recombinant efficiency was 93%.The insert size was about 800-4000bp after electrophoresis *** determine the quality of cDNA library,305 clones were randomly selected to be sequenced by single pass *** all the 305 ESTs,238 ESTs were determined to be novel with E-value below *** redundancy of the cDNA library was 13.4%after clustering analysis and the sequencing accuracy of the EST sequences was far more than 99%.It is feasible to utilize the cDNA library to carry out large-scale EST sequencing.

关键词： Trichoderma harzianum cDNA library ES

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Stationary Set and Stability: a Case Study for Mechanical Systems with Discontinuities

Stationary Set and Stability: a Case Study for Mechanical Sy...

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第二十六届中国控制会议

This paper focuses on the position control of a class of mechanical systems with static friction force.A discontinuous mapping is introduced to represent the static friction such that the closed-loop systems are described by the differential equations with discontinuous right-hand *** on the Filippov’s framework,it’s proved the equilibrium set of the closed-loop systems under PD control corresponds to a stationary mode,and the size of the equilibrium set can be regulated as small as possible with feasible feedback ***,we will show that the positioning error can be rendered into such equilibrium *** demonstrate the presented theoretical results,the experiments tested on a three-axis flight simulation table are carried out.

关键词： Nonlinear systems Discontinuous Nonsmooth

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The Research of Ultra-wideband Narrow Pulse Circuit Based on Avalanche Effect Theory

The Research of Ultra-wideband Narrow Pulse Circuit Based on...

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第二十九届中国控制会议

作者： LIU Weichao,HAO Weilai Computer and Information engineering department,heilongjiang institute of science and technology,harbin 150027,P.R.china

The present situation of wireless communication in the coal mine underground is *** ultra wideband（UWB）wireless communication technology is proposed to be used in the coal mine *** to the amplitude-frequency characteristics of UWB pulse,the theory of transistor avalanche effect and its operation principle is analyzed in *** this way multi level parallel and simultaneous trigger narrow pulse generation circuit is designed and realized by simulation,which can increase amplitude of pulse,decrease delay and breadth of *** circuit can work stably and has high reliability,which can be used in different communication fields by correcting its parameters.

关键词： UWB Narrow Pulse Avalanche Effect Cascade

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Self-tuning Weighted Measurement Fusion Kalman Filter with Cooperating Identification for Multisensor System with Correlated Noises

Self-tuning Weighted Measurement Fusion Kalman Filter with C...

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2011 Chinese control and Decision Conference（CCDC）

作者： Hao Gang1,Li Yun2,Sun Lai-jun1 (1.heilongjiang University,Electronic engineering institute,heilongjiang,harbin,150080,china 2.harbin University of Commerce,School of Computer and Information engineering,heilongjiang,harbin,150001,china)

For the multisensor system with correlated noises and unknown noise statistics,the measurement function can be dealt with in a unified way to form a new tracking system by least square *** result of the measurements can make some groups of steady random sequence,and the variances Rii and covariance Rij of these measurements can be yielded by the matrix equations of the correlation function,and then the estimates of Qw T can be *** the self-tuning weighted measurement fusion Kalman filter is obtained.A simulation example for a tracking system with 3 sensors shows its fast convergence and exactness.

关键词： Noise statistics estimation Self-tuning Kalman filter Weighted measurement fusion

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有关R(n)的一个猜想(英文)

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黑龙江大学自然科学学报 2012年第4期29卷 466-473页

作者：徐闯徐润章哈尔滨工业大学数学系哈尔滨150001 哈尔滨工程大学理学院哈尔滨150001

针对一个关于算数函数R(n)的有趣的猜想。R(n)是一个与所有可以整除n的正整数之和有关的函数。首先利用唯一分解定理建立一些有关R(n)单调性的预备性结果。通过对n做唯一分解,对某类特殊的n,得到一些R(n)的上下界估计。这样,在某种意义... 详细信息

针对一个关于算数函数R(n)的有趣的猜想。R(n)是一个与所有可以整除n的正整数之和有关的函数。首先利用唯一分解定理建立一些有关R(n)单调性的预备性结果。通过对n做唯一分解,对某类特殊的n,得到一些R(n)的上下界估计。这样,在某种意义上,证明了猜想。其次得到了对于某类n的R(n)的上无界性。给出了R(n)=1的充要条件。事实上,R(n)=1当且仅当n为素数。其次,给出对于某些n,使得R(n)=2的充要条件。利用预备知识,进一步研究了R(n)的单调性。得出对于固定的k≥2,至多有一个这样的n使得R(n)=k这样的结论。最后给出使得R(n)=2的具体的n的例子,并计算了10 000以内的R(n)的数值,这样在10 000以内,验证了猜想。

关键词：算数函数上无界单调函数猜想

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