Showing papers by "Harbin Engineering University published in 2006"

Analysis of the displacement amplification ratio of bridge-type flexure hinge

Abstract: The bridge-type flexure hinge is a classic displacement amplification mechanism The existing models of theoretic displacement amplification ratio of bridge-type flexure hinges are not perfect This makes it very difficult to design and manufacture a satisfactory structure using these models Kinematic theory was used to analyze the ideal displacement amplification ratio of a bridge-type flexure hinge in this paper, and the flexure hinge was regarded as a pure multi-rigid body with ideal pivots Elastic beam theory was used to analyze the theoretic displacement amplification ratio when considering the translational and rotational stiffness of the flexure pivots The model of theoretic displacement amplification ratio explains why the bridge-type displacement amplification mechanism has an amplification ratio extremum and where the threshold is The finite element method was used for comparison with the mathematical model, and similar results were obtained Finally, the finite element method was used to analyze the shape mode of the structure The result showed that increasing the amplification ratio by decreasing the thickness of the flexure pivots led to a decrease in the mode shape frequency of the bridge-type structure Thus, redesigning of the structure was needed to solve the problem

The enhanced ethanol sensing properties of multi-walled carbon nanotubes/SnO2 core/shell nanostructures

Abstract: Multi-walled carbon nanotubes/SnO2 (CNT/SnO2) core/shell nanostructures were synthesized by a simple wet-chemical method The thickness of the SnO2 shell was about 10 nm and the diameters of the SnO2 particles were 2–8 nm Sensors based on the core/shell heterostructures exhibited enhanced ethanol sensing properties The sensitivity to 50 ppm ethanol was up to 245, and the response time and recovery time were about 1 and 10 s, respectively In addition, the fluctuation of the sensitivity was less than ± 3% on remeasurement after 3 months These results indicate that the core/shell nanostructures are potentially new sensing materials for fabricating gas sensors

On potential wells and applications to semilinear hyperbolic equations and parabolic equations

Abstract: In this paper we generalize the family of potential wells to the initial boundary value problem of semilinear hyperbolic equations and parabolic equations u tt - Δ u = f ( u ) , x ∈ Ω , t > 0 , u ( x , 0 ) = u 0 ( x ) , u t ( x , 0 ) = u 1 ( x ) , x ∈ Ω , u ( x , t ) = 0 , x ∈ ∂ Ω , t ⩾ 0 and u t - Δ u = f ( u ) , x ∈ Ω , t > 0 , u ( x , 0 ) = u 0 ( x ) , x ∈ Ω , u ( x , t ) = 0 , x ∈ ∂ Ω , t ⩾ 0 , not only give a threshold result of global existence and nonexistence of solutions, but also obtain the vacuum isolating of solutions Finally we prove the global existence of solutions for above problem with critical initial conditions I ( u 0 ) ⩾ 0 , E ( 0 ) = d or I ( u 0 ) ⩾ 0 , J ( u 0 ) = d So Payne and Sattinger's results are generalized and improved in essential

Reduced-temperature ethanol sensing characteristics of flower-like ZnO nanorods synthesized by a sonochemical method

Abstract: Flower-like ZnO nanorods with diameters less than 15?nm were synthesized by a sonochemical method The sensors fabricated from the nanorods exhibited excellent ethanol sensing properties At the working temperature of 300??C, their sensitivity was 1768?100?ppm ethanol vapour While the working temperature was reduced to 140??C, they were still able to detect ethanol vapour at the ppm level The reduced working temperature may be attributed to the small sizes of the nanorods

Sustainable approach for leachate treatment: electricity generation in microbial fuel cell.

Abstract: Electricity generation from landfill leachate was examined by using both a dual-chamber microbial fuel cell (MFC) and a single chamber MFC. Experimental results showed that the maximum power density of 2060.19 mW/m3 in the dual-chamber MFC and that of 6817.4 mW/m3 in the single chamber MFC were obtained. It was recognized that the difference in internal resistance for two MFC systems was the main reason for resulting in the difference of power generation. Power generation as function of chemical oxygen demand (COD) in single chamber MFC showed a Monod-type relationship with Pmax of 5920.96 mW/m3 and Ks of 251.39 mg/L at an external resistance of 500 Omega. Cyclic voltammetry showed that electrons were directly transferred onto the anode by bacteria in biofilms, rather than self-produced mediators of bacteria in the solutions. At low COD concentration, electricity generation was limited by the anode due to kinetic limitation; while at high COD concentration, the cathode was shown to have more significant effects on the electricity generation than the anode. COD in leachate could be removed when it increases, mainly because oxygen diffused from the cathode was substantially reduced by aerobic or anoxic bacteria in the anode chamber, leading to the substrate loss. Removal of ammonium-nitrogen was not observed in the single chamber MFC. This novel technology provides an economical route for electricity energy recovery in leachate treatment.

Review of magnetorheological (MR) fluids and its applications in vibration control

Abstract: Magnetorheological (MR) fluids are now well established as one of the leading materials for use in controllable structures and systems. Commercial application of MR fluids in various fields, particularly in the vibration control, has grown rapidly over the past few years. In this paper, properties of magnetorheological (MR) fluids, its applications in suspensions of vehicles, suspension of trains, high buildings cable-stayed bridges have been discussed. The scope of MR fluids in future, problems and some suggestions are also presented. Finally, effectiveness of MR fluids in vibration control of marine diesel engine through experiment is briefly discussed by the author.

Direct Electrochemistry of Multi-Copper Oxidases at Carbon Nanotubes Noncovalently Functionalized with Cellulose Derivatives

Abstract: This study describes the direct electron transfer of multi-copper oxidases, i.e., laccase (from Trametes versicolor) and bilirubin oxidase (BOD, from Myrothecium verrucaria) at multiwalled carbon nanotubes (MWNTs) noncovalently functionalized with biopolymers of cellulose derivatives, i.e., hydroxyethyl cellulose (HEC), methyl cellulose (MC), and carboxymethyl cellulose (CMC). The functionalization of the MWNTs with the cellulose derivatives is found to substantially solubilize the MWNTs into aqueous media and to avoid their aggregation on electrode surface. Under anaerobic conditions, the redox properties of laccase and BOD are difficult to be defined with cyclic voltammetry at either laccase/MWNT-modified or BOD/MWNT-modified electrodes. The direct electron transfer properties of laccase and BOD are thus studied in terms of the bioelectrocatalytic activities of the laccase/MWNT-modified and BOD/MWNT-modified electrodes toward the reduction of oxygen and found to be facilitated at the functionalized MWNTs. The possible application of the laccase-catalyzed O2 reduction at the laccase/MWNT-modified electrode is illustrated by constructing a CNT-based ascorbate/O2 biofuel cell with the MWNT-modified electrode as the anode for the oxidation of ascorbate biofuel.

Hand Vein Recognition Based on Multi Supplemental Features of Multi-Classifier Fusion Decision

Abstract: As a kind of biometric feature authentication system, hand vein recognition has more merits than others. So it has a vast foreground. In this paper, a new algorithm based on multi supplemental features of multi-classifier fusion decision is proposed. It overcomes the disadvantages of the single feature recognition. Experimental results indicate that the proposed methods can significantly improve the recognition accuracy and reliability compared to the previous hand vein recognition.

In-fiber integrated Michelson interferometer.

Abstract: A novel fiber-optic in-fiber integrated Michelson interferometer has been proposed and demonstrated. It consists of a segment of two-core fiber with a mirrored fiber end. The sensing characteristics based on the two-core fiber bending, corresponding to the shift of the phase of the two-core in-fiber integrated Michelson interferometer, are investigated.

Underwater Swimming Micro Robot Using IPMC Actuator

Abstract: In the medical field and industry application, fish-like microrobot and micro biped robot with multi DOF that can swim smoothly in water or aqueous medium has urgently been demanded. And IPMC (ionic polymer metal composite) can generate large bending motions under a low driving voltage (about 1 V), and it has a good response and soft characteristic. Therefore, we have developed a fish-like S-shape swimming robot, propulsion using IPMC actuator as a body and a tail fin for a micro robot swimming structure. The experimental results indicate that the swimming speed of underwater fish-like microrobot can be controlled by changing the frequency of input voltage. In addition, we put forward a study project, which a wireless biped robot with four legs, which is driven by the IPMC actuator and DSP (Digital Signal Processor).

A new type of hybrid fish-like microrobot

Abstract: In order to develop a new type of fish-like microrobot with swimming, walking, and floating motions, in our past research, we developed a hybrid microrobot actuated by ionic conducting polymer film (ICPF) actuators. But the microrobot had some problems in walking and floating motions. In this paper, we propose a concept of hybrid microrobot (see Fig. 1). The microrobot is actuated by a pair of caudal fins, a base with legs and an array of artificial swim bladders. We have developed a prototype of the base with legs and one artificial swim bladder, respectively, and carried out experiments for evaluating their characteristics. Experimental results show the base with legs can realize walking speed of 6 mm/s and rotating speed of 7.1 degrees/s respectively, and the prototype of the artificial swim bladder has a maximum floatage of 2.6 mN. The experimental results also indicate that the microrobot has some advantages, such as walking motion with 2 degrees of freedom, the walking ability on rough surface (sand paper), the controllable floatage, etc. This kind of fish-like microrobot is expected for industrial and medical applications.

Arm Rehabilitation Robot Impedance Control and Experimentation

Abstract: This paper is devoted to design a robot control system for assisting in the rehabilitation of patients who suffer from debilitating illness such as stroke. The rehabilitation robot discussed in this subject is able to guide patient's wrist to move along planned trajectory in both horizontal and vertical plane, and train the elbow joint as well as shoulder joint. Increasingly the robot requires interacting directly with human, so it needs to control not only the robot position but also the applied forces. In this paper, it presents a new position-based impedance control that involves a combined force feedback and position control. At the meantime, it gives a conversion relationship between the commands of force and position. A new controller structure is proposed, which consists of an outer force controller enhanced by impedance control. The target impedance model modifies a desired trajectory according to the force signals. The modified trajectory acts as a compensate resource adding to the desired trajectory. Then the robot tracks the trajectory using the inner position controller. The experiment results show that the trajectory tracking based on force feedback on the condition of realizing the target impedance is feasible, and it can achieve better training effect by chosen different impedance parameters in the light of patient's illness.

Coupling characteristics between single-core fiber and multicore fiber.

Abstract: A simple method for coupling between a single-core single-mode fiber and a multicore single-mode fiber is proposed and demonstrated. An effective coupling approach is based on a process of standard splicing and tapering between the single-core single-mode fiber and the multicore single-mode fiber.

Study of Network Security Situation Awareness Model Based on Simple Additive Weight and Grey Theory

Abstract: Network security situation awareness is a new technology to monitor network security, and it is one of hot research domains in information security. The research situation of situation awareness all over the world is first analyzed. Network security situation awareness model (NSAM) based on simple additive weight and grey theory is presented. The construction of NSAM is divided into two stages: current network security situation evaluation modeling and future network security situation prediction modeling. The model of current network security situation evaluation using simple additive weight is established by the threat degree of various services attacked. The model of future network security situation prediction adopting grey theory is built by past and current network security situation. Test results show that NSAM is feasible and reasonable.

An Improved Ostu Method for Image Segmentation

Abstract: The Ostu method is one of the applied methods of image segmentation in selecting threshold automatically for its simple calculation and good adaptation. This paper describes an improved method of threshold selecting, through the gray level and gradient mapping (GGM) function. The result of simulation demonstrates that, the new algorithm described in this paper can detect the object and restrain the noise effectively. The algorithm has a widespread application prospect

Forward kinematics of the Stewart platform using hybrid immune genetic algorithm

Abstract: The Stewart platform's unique structure presents an interesting problem in its forward kinematics (FK) solution. It involves the solving of a series of simultaneous non-linear equation and, usually, non-unique, multiple sets of solutions are obtained from one set of data. In addition, most effort has been done in solving the forward kinematics solution of the Stewart platform by means of numerical methods. This paper presents a hybrid immune algorithm (IA), genetic algorithm (GA) and fuzzy system (FS) method for solving the FK problem of the Stewart platform. First, we combined the IA and GA, then we added the fuzzy system approach. The penalty function was also considered in the solution. This hybrid system was then used to solve the FK problem. Numerical simulations were carried out using a series discrete points, the results showed good optimization. A comparison with standard genetic algorithm (SGA) and IGA combined with the FS (IGAFS) was carried out. The result show that the IGAFS cost much fewer time than SGA under the same condition. The result demonstrated the accuracy of the proposed IGAFS approach

Underwater Image Segmentation with Maximum Entropy based on Particle Swarm Optimization (PSO)

Abstract: The contrast of the underwater images is often extraordinarily low due to the ray, assimilating of water, illuminating condition and so on. It is not good for the pretreatment like edge detection and image segmentation. The theory of entropy has been widely used in the pre-process of under water images. However the time-consuming computation is often an obstacle in real time application systems. In this paper, the image thresholding approach with the index of entropy maximization of the grayscale histogram based on a new optimization algorithm, namely, the particle swarm optimization (PSO) algorithm is proposed to deal with underwater image. The experiments of segmenting the underwater images are illustrated to show that the proposed method can get ideal segmentation result with less computation cost.

WC reinforced surface metal matrix composite produced by plasma melt injection

Abstract: WC reinforced surface metal matrix composites (SMMCs) were produced with plasma melt injection (PMI) process on low carbon steel substrate. In the middle and bottom of the SMMC layer, the carbides were mainly M 6 C primary carbides. In the top part, the injected WC particles did not dissolve into the base metal. In the second pass, W content was lower in the top part, and carbides appeared as herringbone structure. In the middle part, M 6 C carbides were larger than those in the single pass. W content was higher in the bottom part, and carbides appeared as WC or partially dissolved tungsten carbides.

Realization of a Catheter Driving Mechanism with Micro tactile sensor for Intravascular Neurosurgery

Abstract: MIS (minimum invasive surgery) as a new method for intravascular neurosurgery has attracted most of doctors and patients in recent years. But there are several problems in intravascular neurosurgery: doctors' operating under X-ray, few well skilled doctors and high risk of the catheter insertion. In order to solve these problems, we develop a highly precise remote control system by a Master-Slave system. A simple micro tactile sensor helping us to feel the contact force is also developed for this system. In this paper, we expatiate on the design concept of the system and carry out experiments to test the precision of the system and the characteristic of the tactile sensor. The experiment results basically achieve our design purpose.

A new phase transformation constitutive model of shape memory alloys

Abstract: As the phase transformation temperatures influence the phase transformation behaviors of shape memory alloys, a constitutive model which can predict their phase transformation behaviors is necessary. In this study, a series of DSC tests is conducted to determine the phase transformation temperatures of shape memory alloy, and a new constitutive model, based on the DSC results, is suggested to predict the phase transformation behavior. Such a constitutive model is formulated on the phase transformation peak temperatures as well as the phase transformation starting and finishing temperatures. Numerical calculations are also conducted in order to verify the capability of the constitutive model through comparing the results with Liang's model. According to the results, the suggested model can be used to predict the phase transformation behavior more precisely due to the fact that it contains the phase transformation peak temperatures as well as the phase transformation starting and finishing temperatures.

Novel Algorithms for Coordination of Underwater Swarm Robotics

Abstract: Swarm robotics is a new paradigm of robotics being developed recently based on swarm intelligence Though the implementation of swarm robotics is still in early stage, great deals of researches in this field have been done This paper proposes novel algorithms for coordination of underwater swarm micro-robots to realize aggregation, formation and flocking The relative numerical simulations have proved the effectiveness of these algorithms

Rapid transfer alignment based on unscented Kalman filter

Abstract: This paper presents a nonlinear error model based on the quaternion for the rapid transfer alignment of the inertial navigation system (INS). It allows the large initial misalignment uncertainty. Then, the unscented Kalman filter (UKF) is designed to achieve the nonlinear filtering based on the proposed model, and utilizes the difference in velocity and attitude between the slave and master INS as the measurement variables. This paper analyzes and compares the misalignment estimation error and convergence rate of the proposed algorithm with the rapid alignment prototype (RAP) and the velocity-only matching algorithm. The results of simulation suggest that the proposed algorithm could achieve the same alignment performance, not limiting the initial attitude error, as the rapid alignment prototype to do when the misalignment is small. The convergence rate of the azimuth misalignment using the proposed algorithm is rapider than using the velocity matching algorithm for large heading uncertainty.