In this work, a novel silicon-based sensor for pressure and flow measurements is presented.
To meet the special requirements of the aerospace industry a new piezoresistive pressure sensor with a
flat surface has been developed, so that the flow is not affected by the sensor. To avoid bonding-wires
on top of the sensor a special through-wafer connection is presented. By making other significant
changes in the layout as well as in the micro fabrication process, a novel sensor has been created. It is
robust enough to be laminated in fibre material, which opens new possibilities for measurements. With
this sensor it is possible to characterize the condition of the flow near the separation point. This article
describes the complete process from the development to the laminated sensor.
We present a new method for detecting and identifying bacteria by measuring
impedance fluctuations (impedance noise) caused by ion release by the bacteria
during phage infestation. This new method significantly increases the measured
signal strength and reduces the negative effects of drift, material aging,
surface imperfections, 1/f potential fluctuations, thermal noise, and amplifier
Comparing BIPIF with another well-known method, bacteria detection by SEnsing
of Phage Triggered Ion Cascades (SEPTIC), we find that the BIPIF algorithm is
easier to implement, more stable and significantly more sensitive (by several
orders of magnitude). We project that by using the BIPIF method detection of a
single bacterium will be possible.
In this work we report the synthesis, microstructure, electric properties and sensing performance of (Sn 0.2Ti 0.8) O 2 (ST) powder, were prepared by wet chemical method. Thick films were prepared by screen-printing technology. Structural and electrical analyses were performed and the results have been correlated. The pure ST film shows good response (S=12.6) to Cl 2 at 350 °C for gas concentration 400 ppm and CuO-modified ST film improves the selectivity and sensitivity and maximum response (S=50.2) was found to H 2S gas at 400 °C for same gas concentration. The characterization of the films was done by XRD, SEM and TGA. Crystallite size, surface area, Electric properties and gas sensitivity of the films were measured and presented.
Planar all solid-contact ion-selective microelectrodes (ASC-μISEs) with a conducting polymer (polypyrrole doped with cobaltabis(dicarbollide) anion [3,3′-Co(1,2-C2B9H11)2]) as a solid contact layer between the polymeric membrane sensitive to lithium (Li) and the gold (Au) substrate were prepared and investigated. The N,N-dicyclohexyl-N′,N′-diisobutylyl-cis-cyclohexane-1,2-dicarboxamide (ETH 1810) was used as ionophore for Li recognition. The developed microelectrodes show a linear response for Li+ concentration between 6×10-5 M and 1×10-1 M with slope of 53±1 mV per decade and exhibits remarkably enhanced selectivity for Li over other cations. The calibration plots using artificial serum containing three different levels of sodium chloride (NaCl) (135, 145 and 155 mM) as a background electrolyte were shown a linear response with a slope of 50 mV per decade in the clinical range of interest (0.7-1.5×10-3 M Li+). The developed microelectrodes will be used to determine Li+ concentrations in serum samples of manic-depressive patients under Li treatment.
This article puts forward parallel forward error correction(FEC) codec for 10 Gb/s Ethernet passive optical network (10G-EPON), which adopts 8-parallel algorithm based on improved state space transformation (SST) method for Reed-Solomon (RS) encoder and 9-parallel algorithm based on enhanced degree computationless modified Euclid's (EDCME) algorithm to solve the key equation for RS decoder. The designed 10 Gb/s codec and high-speed synchronizer are implemented with Verilog HDL on Xilinx FPGA ML523. The implementation results show that, with the high-speed synchronizer, the RS (255, 223) encoder and decoder are able to operate at 15.232 Gb/s and 13.2 Gb/s respectively with shorter time latency than those of the reported designs.
Aimed at the vibration problem of the rolling mill, by using the large FEM software ANSYS, modal analysis of the rolling mill is did. The natural frequency and the vibration models of rolling mill model are obtained. Analysis the simulation results, the causation of the vibration is found, and the solutions are proposed, which provides references for the designing of mill and restraining mill vibration.
This study proposes a framework of data transmission terminal in remote warning control system based on CDMA 1X network. According to the functional requirements of wireless broadband communication system, the hardware interfaces and software of the CDMA 1X data transmission terminal are designed detailedly and the system is implemented using wireless access and embedded development technologies. It has good applicability and portability so that various wireless data transmissions can be achieved by replacing the data source module.
Wireless sensor network is a popular technology on information acquisition and processing, which has been widely used in plantation ecological monitoring domain. The plantation environments, including antenna height-gain, depolarization, terrain, humidity and many factors have great influences on the propagation of 2.4GHz wireless sensor network radio frequency signal. In this paper, a complete research for propagation law of 2.4GHz wireless sensor network signal in plantation environment is presented, with using regression of support vector machines based on experimental data. A single variable prediction model is established on field strength of wireless sensor network signal in plantation environment, thus compares it with the original experience prediction model and measured data. The establishment of aforesaid model provides an important theoretical support for determining the max effective communication range of wireless sensor node and the nodes' rational distribution. It will certainly promote the application of wireless sensor network in plantation ecological monitoring field.
To aim at the reliability and security issues of ZPW-2000A Jointless Audio Frequency-shift Modulated Track Circuit System, Failure Modes Effects and Diagnositcs Analysis (FMEDA) and Fault Tree Analysis (FTA) were proposed for reliability and security analysis of system. The system was analyzed and defined, the FMEDA table was completed, and the fault tree was built, then the qualitative and quantitative analyses of the fault tree were conducted. The minimal cut sets of the fault tree were got by qualitative analysis, and the weak links of the system were located. The fail probability of roof events, important degree of each minimal cut sets and the indicators of reliability and security were gained through the quantitative analysis. The paper provides a practical method and theoretical basis for the reliability and security analysis of ZPW-2000A track circuit system.
Motion capture systems play an important role in health-care, sport-training systems and cartoon animation. This paper develops a motion capture system with inertial motion trackers for three-dimensional animation production. The system mainly involves inertia sensing technology, Bluetooth, sensor network and software development of human body motion capture model. The sensor network is used to collect motion data of the body key joints, and the data are delivered to workstation through Bluetooth, then the software on workstation uses analytical inverse kinematics algorithm to analyze the motion data. Human body motion capture system mainly involves the design of human body model and development of real-time reconstruction software. A human body is abstracted into 17 key joints affecting human movement for model, and inertial sensors are put on each joint point to measure the motion data of the node, so a 17 nodes sensor network is built. The experiment shows that the model tends to handle uncertainty well and the software and hardware of motion capture system have advantages of good consistency of virtual character and performer athletic stance and farther effective communication distance, and it is very easy to further expand the research of this subject, such as the design of multiplayer real-time motion capture system.
In this paper, an effective video watermarking method based on H.264/AVC was proposed. We select Intra_4×4 and Intra_16×16 as the embedding target, each macroblock would be embedded into 1 bit watermark. In Intra_4×4, we explorer the characteristic of the DCT coefficient and adjust them to embed watermark while in Intra_16×16 we modulate the LSB bit of the DC coefficient to realize watermark insertion, furthermore, we control the embedding strength to make the video quality and the bit-rate acceptable. Experiment results demonstrate that the watermark can resist the recoding effectively, while the real-time performance can also be obtained. Copyright
Virtual human body models are used in many applications that allow human-machine interaction. The measurement of the position of a particular limb in the human body is extremely important in many applications. Human behavior understanding typically involves human body posture analysis or estimation, as well as the generated corresponding gestures. In order to provide a contribution in the referred area, this paper presents the development of an experimental gait analysis system during human walking by videogrammetry, accelerometry and virtual models. The principle of the experimental system is developed to capture the walking image using low-cost webcams, with the support of colored markers placed on the targeted joints. When the subject walks, the system captures and processes the events and determines the angles of the body segments. Parallel to this process, an accelerometer network distributed on the user's body reads these movements, to compare the measurements. Additionally, the results of the videogrammetry system were compared to the DMAS16 Spica Tech system. For result assessment, a virtual body model is presented in real-time motion with data being stored in a database for future evaluations and analyses. The system proposed in this paper showed an average difference of 3.1°, has low cost, and is suitable for a wide range of applications.
The purpose of this paper is to develop a new technique for estimating the two-dimensional (2D) direction-of-arrivals (DOAs) of coherently distributed (CD) sources, which can estimate effectively the central azimuth and central elevation of CD sources at the cost of less computational cost. Using the special L-shape array, a new approach for parametric estimation of CD sources is proposed. The proposed method is based on two rotational invariance relations under small angular approximation, and estimates two rotational matrices which depict the relations, using propagator technique. And then the central DOA estimations are obtained by utilizing the primary diagonal elements of two rotational matrices. Simulation results indicate that the proposed method can exhibit a good performance under small angular spread and be applied to the multisource scenario where different sources may have different angular distribution shapes. Without any peak-finding search and the eigendecomposition of the high-dimensional sample covariance matrix, the proposed method has significantly reduced the computational cost compared with the existing methods, and thus is beneficial to realtime processing and engineering realization. In addition, our approach is also a robust estimator which does not depend on the angular distribution shape of CD sources.
In this paper, routing algorithm has been mainly studied. The main work and contribution have been generalized as follows: Through the research of Internet and NoC's (Network on Chip) deterministic and adaptive routing, DRM (Dynamic Routing Mesh) algorithm which is combined deterministic and adaptive routing algorithm has been designed, which not only ensures connectivity of any couple of communication nodes but also just requires only two virtual channels. Furthermore, the DRM routing algorithm is for solving the irregular 2D mesh topology, and the method has been designed which is used for the choice of path. Simulation results show that, DRM routing algorithm compares with Boppana and Virtual Network algorithm has certain performance advantages.
The amplitude difference of the sediment layer’s echoes is always so large that the acoustic time difference becomes much difficult to get correctly. The existing methods of time varying enhancement for the multipath signal like ultrasonic echo have some limits in de-noising or practical application. This paper employs the second Iterative Passive Time Reversal Mirror to accomplish time varying enhancement for the ultrasonic signal. According the principle of measuring the sediment thickness in borehole by ultrasonic, the paper has established the system model to describe the processing of ultrasonic transmitting through the mud-sediment media, and simplified the channel in a linear, space-invariant, time-invariant multipath channel with two paths. Based on the model, the process of enhancing echoes of sediment layer by 2nd Iterative Passive Time Reversal Mirror is presented. Using the echoes of sediment with different thickness obtained in lab circumstance, two typical experiments to enhance the echoes have been taken. From the two experiments’ results we can see, 2ndIterative Passive Time Reversal Mirror is sure to give the later arrival echo bigger gain than to the earlier one, thus reduce the amplitude difference of the two echoes.
Strontium Titanate (SrTiO 3, (ST)) was prepared mechanochemically from Sr(OH) 2 and TiO 2. XRD confirms the perovskite phase of material. Thick films of ST were prepared by screenprinting technique. The gas sensing performances of thick films were tested for various gases. It showed maximum sensitivity to CO gas at 350°C for 100 ppm gas concentration. To improve the sensitivity and selectivity of the film towards a particular gas, ST thick films were surface modified by dipping them into the solution of nano copper for different intervals of time. These films were found to be sensitive towards 1 ppm of H 2S at Room Temperature. The response was reproducible and the films were stable for operation over three months. The detection mechanism of the sensors was investigated and it was found that the Cu would be transformed upon firing into copper oxide. The p-type CuO grains around n-type ST grains would form n-ST/p-CuO hetero-junction. Upon exposure to H 2S gas, the barrier height of n-ST/p-CuO hetero-junctions decreases markedly due to the chemical transformation of p-CuO into well conducting CuS leading to drastic change in resistance. The efforts have, therefore, been made to develop the Room Temperature H 2S gas sensor based on strontium titanate surface modified with nano Cu. The gas response, selectivity, stability of sensor, response and recovery time of the sensor in the presence of H 2S gas were studied.
This paper presents H 2S gas sensing properties of WO 3 pellets at room temperature. In this work, the WO 3 pellets were prepared by standard solid state method. The prepared pellets were characterized by x-ray diffraction (XRD) measurements and scanning electron microscopy (SEM). The H 2S gas sensing properties of WO 3 pellets were investigated at room temperature and at different concentrations of gas. The WO 3 pellet exhibit excellent H 2S gas sensing properties in air atmosphere at room temperature with fast response and recovery time.
This paper proposes a coarse-to-fine 3D keypoint detection method based on Principal Component Analysis and Harris operator. At first, the local neighborhood of each vertex is determined according to the conception of "ring". Then the Principal Component Analysis method is performed on the local surface, and the ratio between the first two principal axes of the local neighboring surface is used for selecting candidate keypoints. Finally we compute the Hessian matrix of the local surface through paraboloid fitting, and the Harris operator is used to obtain final keypoint. Extensive experimental results have testified the effectiveness of the proposed method, and it is more robust to noise, especially to high level noise.
This work proposed a real-time 3D map building system based on the visual odometry information derived from a Multi-Camera hardware. The accurate odometry information and images derived from the proposed intuitive Multi-Camera hardware, so called Multi-Camera Unit (MCU), are used as an input for the 3D map building process which cooperates the FastSLAM algorithm as a map and path estimator. Experiment results show that the proposed system yield good estimation of 3D path and map in real-time. Using the estimated 3D path and map, a showcase application of 3D photorealistic map building can be implemented with ease where it can be run on top of all process in real-time manner using a standard PC.
How to refresh frames for 3D scenes efficiently with viewpoint movement is very important for a 3D walkthrough system. Detailed calculation process of movement position and destination position for the viewpoint in virtual 3D scenes is described, thus implementing controlling scenes through the application of an external device. Moreover, OpenGL Performer pfLOD node is utilized to process LOD (Level of Detail) display for improving scenes refreshment performance. With OpenGL's powerful interaction functions, 3D scenes are rendered with a fixed frame rate over 50 Hz. Then, details of MFC framework initialization and OpenGL initialization are given for Dalian nationalities university 3D walkthrough system. Running results of the software show the algorithm designed in this paper is feasible and effective and can meet requirements of real application.
This paper presents a novel surface reconstruction algorithm based on 3D point cloud sliced by a series of planes vertical to Z-axis. First, the density and distribution of point cloud is analyzed in vertical direction Z-axis and a stratified point cloud model is put forward to present an object feature, in which point cloud is sliced with irregular intervals. An approach of stratified point cloud projected on plane is proposed. The algorithm based on Delaunay triangulation technique in two dimensions gain quickly the local topological connection relationships between points. Further, the planar triangular mesh is mapped into 3D-TIN. Finally, the object surface model is composed of the stratified 3D-TINs with consistent edges. Two tests are implemented to demonstrate that the algorithm is very simple, robust and suitable to reconstruct the object surface based on complex shaped and irregular 3D point cloud.
In recent years Terrestrial Laser Scaner (TLS) is widely used in complex scene survey and space objects measurement, however, due to the trees' irregular and complex morphology, also the scanning results be effected by the wind blowing and occlusion effect, so quantifying the 3-D morphology structure and forestry index of an individual tree or a forest stand from Point Cloud Data (PCD) is a challenging task. In this paper, the computer theory is combined into our approach. Firstly the covariance matrixes based on neighborhood information are constructed to retrieve the feature vectors of every PCD, including normal vector, torsion and curvature from the scanning data. Secondly the LLE manifold-learning method is adopted for dimensionality reduction of PCD features, then identification and classification of different plant organs are achieved. Finally orthogonal least squares algorithm about three-dimensional surface fitting is presented to remove deviation caused by leaf jitter, then the whole PCD of singe leave are mapped onto one three-dimensional surface, next, many triangles are used to form the foliage area and Leaf Area Index (LAI) can be calculated based on the delaunay triangulation algorithm. In this paper we apply computer theory to overcome the shortcomings of TLS in forestry application, automatically and nondestructively achieve the classification of different plant organs and 3-D reconstruction of real foliage, most importantly, this work provide a theoretical foundation for retrieving LAI and forestry parameters from PCD obtained with a TLS.
3D SIFP (3 dimensional scale invariant features points) can embody the great changes in video both in spatial and temporal domain, which can assure the stability against spatial and temporal attacks. As a result, they enforce the robustness of video watermarking. In this paper, a novel video watermarking scheme exploiting 3D SIFP in DCT (Discrete Cosine Transform) domain is proposed. We establish the 3D difference of Gaussian pyramid (3D DoGP) and 3D Hessian matrix to locate the 3D SIFP, which are selected by global and local steps. All global SIFP are ordered in ascending order according to their 3D Hessian matrix response values, and SIFP corresponding to the first several global response values are selected to maintain the stability. Afterwards, the SIFP with the largest local response value in detected frame are selected as the center to generate the square embedding region. The region is transformed into DCT domain, and the ZigZag scanned mid-frequency coefficients are segmented to embed the watermark by using modified odd-even quantization. Experimental results show that the proposed scheme guarantees high peak signal to noise ratio (PSNR), and is very robust against noising, filtering, JPEG compression, frame swapping, frame insert, frame dropping, scaling etc.
In this paper, an insole plantar pressure device based on 3-D forces piezoelectric sensor, integrated into a shoe, was developed for monitoring plantar pressure under real-life conditions. The device consisted of an insole with eight measure points composed of piezoelectric sensor, a wireless data transmission and embedded computer. The piezoelectric sensor with ceramic was embedded into the insole assembled by three different directions (3D) of X, Y and Z. The piezoelectric sensors mathematical model was built, and the layout of these sensors in insole was investigated. Based on the FFT algorithm, the eight measurement points data were collected and analyzed taken by frequency. The plantar changes of the left and right foot in 3D direction were measured, respectively. The results were displayed on the software interface, it showed that the insole system can be used to monitor plantar pressure during daily living and is expected to be useful in various clinical applications.
Tire pressure monitoring system (TPMS) plays an important role in automobile safety. One of the important components of TPMS is a MEMS pressure sensor. This paper presents the virtual prototyping of TPMS which involves design, virtual fabrication and system level modelling of a square as well as acircular diaphragm based capacitive pressure sensor for a given stroke length. Intellisuite® MEMS design tool is used for obtaining the virtual prototype. The analytical expression for the sensitivity of square diaphragm in small deflection regime is derived and comparison of calculated results with simulated is presented.
Wireless Sensor Networks (WSNs) have been attracting the attention of both academic and industrial research communities for the past few years. To find an optimal topology control strategy in 3-dimensional (3D) WSNs is a new challenge. In this paper, we discuss issues related to the topology control in 3D WSNs, review a 2D model for WSNs, and introduce a 3D model for WSNs. An Immunity-Based Ant Colony Optimization Topology Control Algorithm for 3D WSNs is introduced, which has better performance with the nature of feedback and paradigm of ant colony and immunity algorithm reducing the redundancy iteration. The advantage of both the Ant Colony Optimization algorithm (ACO) and Connected Dominating Set (CDS) are fully taken in this algorithm. Simulation results show that the CDS-ACO has the better performance in WSNs.
Wireless sensor network as a new information acquisition technology has profound impact on people's work and life style, has the very high research value. Energy issues important factor restricting the development of the deep WSN is node, sensor nodes for processing data collected information and communication between nodes will speed up the energy consumption of nodes. Cover the deployment strategy is directly related to the optimal distribution of target area monitoring the degree of perception and limited resources of wireless sensor network, determines the service quality of the wireless sensor network to improve the. How to design an efficient coverage algorithm directly affects the coverage and network lifetime, because the actual environment of 3D wireless sensor network is more close to people, so the 3D WSN. Covering research has more realistic significance. At present, about the research of wireless sensor network many 3D covering literature, according to the general configuration of nodes is divided into deterministic coverage and random covering two aspects. This paper presents a wireless sensor network node for 3D scene coverage model and its deployment method, based on analyzing the common regular polyhedron models used in 3D space coverage, proposed a model based on covering the structure, on the basis of this theory to derive a quantitative relationship between coverage model and node sensing radius, more based on the quantitative relationship between the further calculation of network area remains fully covering the minimum number of nodes are required, the network regional 3D mesh finite mesh node coverage model in accordance with the deployment.
This paper purposes a solution of the target detection and identification for automatic ship loader. For automatic ship loaders, the operation target should be detected and identified continuously and real-timely. By using the laser measurement systems (LMS), the ship cargo holds and the bulk cargo can b rebuilt as a group of 3D points. Then the image processing algorithm can identify the positions, sizes and shapes of the cargo holds and the bulk cargo from the 3D points. Based on the target information identified by the image processing algorithm, the ship loader can finish the loading operation automatically. At last, this paper describes and analyzes the experiment of the cargo height detection using LMS in Coal Terminal of Tianjin Port.
Volumetric matching is essential for volume image analysis. The main contributions of this paper are: 1) We present an improved 3DSIFT algorithm for volumetric matching. We can extract more correspondences than the state of the art. 2) We introduce anisotropic Gaussian smoothing during the scale space extreme detection step. We find more reliable keypoints than the isotropic one. 3) We present a point-point matching algorithm to solve the one-many matching problem. Experiments on synthetic and real volume images show the superiority of the proposed 3D SIFT over the state of the art.
A wireless image real-time transmission system is designed by using 3G wireless communication platform and ARM + DSP embedded system. In the environment of 3G networks, the embedded equipment has realized the functions of coding, acquisition, network transmission, decoding and playing. It is realized for realtime video of intelligent control and video compression, storage and playback in the 3G embedded image transmission system. It is especially suitable for remote location or irregular cable network transmission conditions applications. It is shown that in the 3G network video files are transferred quickly. The real-time transmission of H.264 video is broadcasted smoothly, and color distortion is less. The server can control client by remote intelligent units.
This study is to examine the relationship between organizational culture and resources integration model. Based on resource-based theory, this study argues that different organizational cultures have different impacts on resources integration model, which in turn contributes to strategic flexibility. Our study undertook a survey of 137 effective samples from manufacturing industries and developed a model of PLS (Partial Least Squares). The empirical results confirm the reliability and validity of measurement scales. The findings show that organizational cultures do contribute to strategic flexibility through resources integration. Manufacturing managers should advocate the adoption of cultures with authoritative control and risk aversion, which will play an important role in external resources integration model through borrowing, alliance, and collaboration.
The parallel and perpendicular magnetic field behaviour of five industrial grade platinum resistance thermometers (Pt 500) has been investigated. Measurements on the sensors were performed at various temperatures between 300 K and 4.2 K in the presence of intense static magnetic fields up to 9 T. The sensor performances were studied for perpendicular and parallel magnetic field. The field dependent temperature errors (ΔT/T) and the relative magneto resistance changes (ΔR/R)are tabulated as a function of field and the temperature.
Thermistors have high sensitivity which makes them suitable for various applications, but they exhibit a highly nonlinear resistance-temperature relationship which is exponential in nature. This nonlinearity is an important problem and a lot of research has been dedicated to correct it. In this paper a virtual instrument has been developed based on the modified 555 timer circuit using LabVIEW to obtain a linearized characteristic over a wide temperature range (0 °C to 120 °C) with reasonably good response linearity, reliability, and overall improved performance. The possibility of developing the proposed instrument as a temperature sensor with frequency as output has been investigated through simulation. It has been shown that the linearization of the thermistor characteristic is achieved by selecting the suitable parameters of the thermistor, the frequency determining elements and the control voltage of modified 555 timer circuit without connecting any additional elements. In a specific range of temperature the proposed circuit is characterized by high temperature stability, improved sensitivity and nonlinearity of about ± 1 %.
According to complex analytic formula for the six degrees of freedom decoupled robot, a detailed analysis of the six degrees of freedom decoupled robot analytic formula of export process, as well the causes of multiple solutions. The method of increasing the local variables to avoid processor running the same statement repeatedly is proposed. The method to find the most frequency formula appeared in analytic solution replaced with local variables facilitate the use of loop to reduce the amount of code. It effectively reduces the computation time, optimize the computing process. Finally, taking PUMA560-like robot as an example, the calculation result is verified and simulated in Robotics Toolbox of MATLAB.
The Auto Anti-Deviation Drilling System (AADDS) is a high-performance, highly automated vertical drilling hydraulic guide control system. This article takes its power extraction device-driving bearing for the study object, analyzed the single-plunger pump's principle, established the mathematical model of hydraulic guide system, applied Matlab/Simulink to simulate the pump outlet flow under different contour curve of the driving bearing. The results show the oval-shaped bearing is of high efficiency under lower drilling speed, and its performance is better than that of original eccentric-shaped and clover-shaped.
In this paper, we firstly provide a brief introduction on the research status and progress of the thermomechanical coupled properties and the actual work process of a wet clutch; we adopt specific research methods to analyze the friction structure and material properties, moreover, appropriate analysis will be made for the working condition analysis, stress features, the causes and factors of thermo-mechanical coupled, and constructing dynamics model under transient conditions. We also research the principles and processes for solving coupled stress, which enable us to obtain the simulation analysis model (Analysis steps, Boundary conditions, Contact algorithm, load, Mesh, Quality scaling factor) based on ABAQUS software. We also further analyze the thermo-mechanical coupled stress and get results from the temperature field, stress field, integrated displacement, axial stress distribution of the dual steel plate and friction plate. At last, we use the results to compare and validate the results of indirect method (ANSYS method), which provides the necessary theoretical basis and guidance for subsequent simulation.
Active Magnetic Bearings (AMBs) have been widely used in industry, aeronautics and astronautics for some significant advantages. The sensor is one of the important parts of the electromagnetic bearing system, the features of the sensor can affect the performance of the whole system. The nonlinear electromagnetic force may cause the considerable oscillations of the rotor with some parametric excitation. Thus, the research on characters of the nonlinear dynamics and the stability for the rotor-ABMs system has practical implication. The works in this current study focus on the study of the existence of the periodic solution, the numerical simulation of the solution and the stability of the periodic solution. Firstly, we present the motion equations of the rotor- ABMs system, by applying the multiple method of scale to the equations, we have the average equations and we get the sufficient condition of the existence of the periodic solution through using transformations, the Poincare mapping and the Melnikov function. Then, we have the phase diagrams by using the Matlab calculation software; we also analyze the phase diagrams which were under different parameters. The simulation results demonstrate the theory of the paper is correct.
A Semantic Sensor Network (SSN) is a sensor network including semantics of sensory data and context information, and relationships between the semantics by using Semantic Web technologies. Even though much research has been activated on SSN, there is little activity on how to restructure concepts in SSN. Research and developments in sensor semantic computing has gained much attention in areas of sensor data mining, sensor semantic, among others. Dealing with large domain concept in this computing environment and its difficulty becomes a difficult task. The idea of concept restructuring is to deal with and reduce the difficulty in dealing with large domain concept and to provide semantics for concept integration, expansion, and update. In this paper, we tackle the task in developing the mechanism to provide the above-mentioned semantics and the framework for processing mechanism integration in concept restructuring using UML-based design. Processing mechanism confirming was conducted to verify towards realizing a workable concept restructuring method.
In this study, firstly, the YL12 aluminum alloy is used as experimental materials, then in the following experiments it is cut in JJ-I-type water jet machines, and 1,000 group data are gotten by measurement. In each group data, pressure, material thickness, surface roughness, abrasive flow and traversing speed are included. Next, BP artificial neural network is established. In this network, there are four inputs and one output. The inputs are pressure, material thickness, surface roughness and abrasive flow rate; the output is traverse speed. And then the BP artificial neural network is programmed by one toolbox of Matlab. Using the former 1,000 group data, the BP artificial neural network is trained, and its forecast function is obtained. Finally, the BP neural network is tested to verify through using different thickness of aluminum alloy verifies its forecast function. According to given pressure, material thickness, roughness and abrasive flow, traverse speed is predicted. The YL12 aluminum alloy is cut by the predicted traversing speed. The maximum error between the prediction values of surface roughness and the actual values of the surface roughness is 6.5%.
Modern civil aircraft requires all-weather frequent landing on permissive runway surface conditions as well as better braking performance. In order to meet such requirements, this paper starts with the kinematics of aircraft Anti-skid Braking System (ABS),and analyses the mathematical models of wheels, tyres and runway, hydraulic servo valves, brakes, etc. The runway identification is established based on Magic Formula, the desired slip ratio is real-time adjusted according to the runway surface condition. On this basis, the fuzzy control with input variables of the slip ratio error and its change ratio is introduced. Simulation and dynamometer tests show that this system has the satisfying braking effect in different runway status. The adaptability and robustness are greatly enhanced and improved, which ensure the successful development of aircraft ABS in integrated environment.
Optical absorbers based on vertically aligned multi-walled carbon nanotubes (MWCNTs), synthesized using electric-field assisted growth, are described here that show an ultra-low reflectance, 100X lower compared to the benchmark, a diffuse metal black - Au-black - from wavelength λ ~ 350 nm - 2500 nm. The reflectance of the MWCNT arrays was measured to be as low as 0.02 % at 2 μm in the infra-red (IR). Growth conditions were optimized for the realization of high-areal density arrays of MWCNTs using a plasma-based chemical vapor deposition (CVD) process. Such high efficiency absorbers are particularly attractive for radiometry, as well as energy harnessing applications. Optical modeling calculations were conducted that enabled a determination of the extinction coefficient in the films.
The traditional HVDC plays an important role in the development of power grid. But the traditional HVDC cannot supply power either to entirely passive AC network or to weak AC system. In fact, an entirely passive AC network can be effectively powered through VSC-HVDC. However, the cost of investment in VSC-HVDC is amazingly high due to the limitation of power electronics technology. Based on CSC and VSC, this paper proposes a method to build Hybrid HVDC, which makes the power supply to the passive AC network come true and, at the same time, lowers the investment cost. The effect of topology, steady mathematical model, startup characteristic, steady and transient characteristics in Hybrid HVDC system are systematically studied in this paper. The simulation result shows that Hybrid HVDC can supply power to the passive AC network with high stability. This study provides a theoretical basis for the further development of HVDC.
A novel artificial neutral network stator flux estimator based on low pass filter for induction motors is proposed in this paper. Firstly, low pass filter is used to extract the features of the stator voltage. Then, the feature signals are selected as inputs of an artificial neutral network regression model to estimate stator flux. The combination stator flux estimation algorithm with low pass filter and artificial neutral network reduces the interference induced by high frequency signals and has fine dynamic performance. Simulations show high performance of the proposed stator flux estimator under different torques.
To control the nonlinearity, widespread variations in loads and time varying characteristic of the high power ac servo system, the modeling and control techniques are studied here. A self-recurrent wavelet neural network (SRWNN) modeling scheme is proposed, which successfully addresses the issue of the traditional wavelet neural network easily falling into local optimum, and significantly improves the network approximation capability and convergence rate. The control scheme of a SRWNN based on fuzzy compensation is expected. Gradient information is provided in real time for the controller by using a SRWNN identifier, so as to ensure that the learning and adjusting function of the controller of the SRWNN operate well, and fuzzy compensation control is applied to improve rapidity and accuracy of the entire system. Then the Lyapunov function is utilized to judge the stability of the system. The experimental analysis and comparisons with other modeling and control methods, it is clearly shown that the validities of the proposed modeling scheme and control scheme are effective.
In order to achieve high quality of products at lesser cost, accurate measurement of different process variables is of vital importance in any industry. There are different well-established techniques of measurement and control instrumentations of these variables. In the resistive transducer like strain gauge, the small resistance generally changes linearly with a process variable like pressure but their measurement by usual AC Wheatstone bridge circuit may suffer from errors due to the effect of stray capacitance between bridge nodal points and ground and stray inductance on the strain gauge grid respectively. Though the conventional Wagner-Earth technique may be used to reduced the error but not suitable for continuous measurement. In the present paper, a modified operational amplifier based AC Wheatstone bridge measurement technique has been proposed in which the effect of stray capacitance and inductance is minimized. This bridge performance has been studied experimentally with the strain gauge type pressure transducer. The linear characteristics over a wide range of pressure with good repeatability, linearity and variable sensitivity have been described.
Piezoelectric force sensors are used in more and more industries and areas for the monitoring of the production process or testing products' performance. In some high-precision testing fields, the dynamic measurement performances of the test system itself have to be examined. Based on the dynamic response mathematical model of test system itself, this paper studies the dynamic measuring acceleration error compensation method. Firstly, according to the motion differential equation of the test system, the dynamic response transfer function is built and the root cause of the test system dynamic testing error is studied. Then the modal parameters of the system are obtained using the experimental modal analysis method and a deterministic response transfer function is established. The acceleration impact item is separated out by the method of separation of variables and weight coefficient method. Combining numerical differentiation, the expression used to calculate the acceleration is achieved. Finally, acceleration compensation experiment is done.
This paper reports the principle of operation, design aspects, experimentation and performance of a polymer fibre optic probe for the measurement of acceleration. The device consists of fibre optic transmitter, fibre optic probe, mini-shaker type 4810, power amplifier type 2706, accelerometer, conditioning amplifier, dynamic signal analyzer, photodiode detector and digital multimeter. In this experiment acceleration is measured simultaneously for different driving voltages of the power amplifier by fibre optic method and from the accelerometer with the help of dynamic signal analyzer and conditioning amplifier. The experiment is repeated with different frequencies of vibration (150, 250, and 350 Hz) and the results are compared. The value of acceleration obtained from accelerometer and the fibre optic probe method are found to be in good agreement with each other. The sensor is capable of sensing acceleration ranging from 40 to 1256 m/s2 within a frequency range of 150 to 350 Hz. The fibre optic sensor is a promising alternative to other well-established methods for the measurement of acceleration due to its simplicity, long term stability, low power consumption, linearity, noise reduction, ruggedness and light weight of the reflective surface mounted on the accelerometer.
Obstructive sleep apnea syndrome is a sleep-related breathing disorder that is caused by obstruction of the upper airway. This condition may be related with many clinical sequelae such as cardiovascular disease, high blood pressure, stroke, diabetes, and clinical depression. To diagnosis obstructive sleep apnea, in-laboratory full polysomnography is considered as a standard test to determine the severity of respiratory disturbance. However, polysomnography is expensive and complicated to perform. In this research, we explore a computer-aided diagnosis system with portable ECG equipment and tri-accelerometer (x, y, and z-axes) that can automatically analyze biosignals and test for OSA. Traditional approaches to sleep apnea data analysis have been criticized; however, there are not enough suggestions to resolve the existing problems. As an effort to resolve this issue, we developed an approach to record ECG signals and abdominal movements induced by breathing by affixing ECG-enabled electrodes onto a triaxial accelerometer. With the two signals simultaneously measured, the apnea data obtained would be more accurate, relative to cases where a single signal is measured. This would be helpful in diagnosing OSA. Moreover, a useful feature point can be extracted from the two signals after applying a signal processing algorithm, and the extracted feature point can be applied in designing a computer-aided diagnosis algorithm using a machine learning technique.