In order to fully explore the energy saving potential of plug-in hybrid electric vehicle with determined power parameters of powertrain and control strategy, and in meeting the vehicle performance constraints, the running cost of 100 km was proposed as the response. The optimal Latin hypercube design was used to investigate the spatial response characteristics of all factors of the transmission system, based on which the key design factors of the system were identified and the optimal local area was confirmed. Combined with making full use of the advantages of strong local optimization ability of nonlinear quadratic programming algorithm, the Radial Basis (RBF) neural network model was established to obtain global optimal solution and the best response of the optimization problem. The model error is 1.06% which shows that the optimization method based on approximation model is of high accuracy. The running cost of 100 km is reduced by 9.72%.

A multi-objective optimization method aiming at minimizing HESS energy consumption and battery capacity loss is proposed. The battery loss is considered as a state variable, then, the multi-objective optimization problem is transformed into single objective with two state variables. The optimization problem is solved using dynamic programming algorithm, thus obtaining the Pareto-optimal sets. The optimization result is analyzed and a series of control rules are acquired, then, based on these rules, a rule-based power slitting strategy is proposed. Finally, the proposed strategy is simulated under Urban Dynamometer Driving Schedule condition. Results show that, compared with dynamic programming results, HESS energy consumption increases by 1%, and battery capacity loss increases by 0.4%, similar effect with dynamic programming is achieved. This proposed online ene4gy management is sub-optimal on both targets.

A hybrid optimization method is proposed based Particle Swarm Optimization (PSO) algorithm and modified Gauss-Newton (S-N) algorithm, which is used for characteristic parameter identification of UniTire model under pure longitudinal slip and pure cornering conditions. Taking the full advantages of the two algorithms, the approximate solutions are identified first using the PSO algorithm, which is superior in global search; then, the optimal solutions of the parameters are obtained in the neighboring region of the approximate solutions by using the modified G-N algorithm, which is superior in local search. The results of residual analysis of the identified parameters show that the parameterized UniTire model with the identified results has high accuracy, and can meet the requirements to establish hardware in the loop simulation test environment for electric control unit of the vehicle chassis.

According to the structure characteristics of multi-link suspension mechanism, the kinematics characteristics of the imaginary kingpin in steering process was analyzed. The theorem of instantaneous screw axis was employed to calculate the movement and the caster offset of the imaginary kingpin. An active return control strategy was proposed and used to compensate the reduced aligning torque caused by the movement of the imaginary kingpin and load transfer. The results show that, using the active return control strategy based on imaginary kingpin kinematics calculation, the return-to-center performance of the vehicle was improved.

In order to decrease the influence of transport delay on driving simulator, a compensator for vision system was built combining the Current Statistical (CS) model and Adaptive Kalman Predictor (AKP) to predict vehicle's position. A simulation model of the driver-driving simulator was proposed. The influence of transport delay on driving behavior was analyzed with this simulation model. Also a comparison between the compensator based on CS model and other two representative compensators, the National Advanced Driving Simulator and an improved McFarland compensator, was done with the proposed model. The results show that the compensator based on CS model has a better compensation effect. The effectiveness of this compensator was also verified on the ASCL driving simulator.

This paper analyzes the musculoskeletal biomechanical characteristics of the bodies of driver and passenger in different sitting positions. Based on musculoskeletal biomechanical computational software, two human sitting musculoskeletal models are built to describe the natural sitting postures of the driver and passenger. Also the influence of the back-rest angle on the muscle and skeleton forces of the driver and passenger is analyzed. This study provides the quantified design bases for humanized automotive seat and accurate sitting position of testing driver and passenger.

In order to satisfy accuracy requirement of testing data for the compiling of dynamic load spectrum of tracked vehicle transmission, the problem of how to deal with the irregular noise, usually existing in the dynamic load spectrum signal, was studied. First, the collected signal is analyzed by power spectrum analysis. The frequency distribution and the characteristics of the load signal were briefly analyzed, and the main distribution range of the useful signal was determined. Then, the wavelet analysis method for dynamic load spectrum signal de-noising was studied, and the calculation method of adaptive threshold developed from universal threshold was presented. Quantificational evaluation based on SNR and MSE, the de-nosing results of typical sine simulation signal with different noise pollution indexes were comparatively analyzed, and the de-noising results of load simulation signal with real noise signal were also comparatively analyzed both using the two methods. Furthermore, combined with the real transmission characteristics in the process of dynamic driving and gear shifting, effective analysis was presented. It shows that the adaptive threshold de-noising method has a better de-noising effect on the premise of keeping useful medium-high frequency dynamic load spectrum signal.

A full-size car interior model was simplified. Realizable k-ε turbulence model and TCM human body heat regulation model were chosen with a reasonable set of solar radiation boundary, then the air temperature, air velocity and air angle parameters were simulated under twelve working conditions. Combined with the overall thermal comfort index deviation A_EGT, cooling load Q, velocity field and temperature field distribution, the effect laws of different parameters on the car interior airflow field were studied from the point of view of comfort and energy efficiency.

The power assembly acceleration, the maximum car-body acceleration and power acceleration stiffness are the most important factors in vehicle passive safety. Therefore, in concept auto design these factors must be considered. In this paper a layout optimization method of the key parts of simplified model of concept auto, equivalent to a mass-spring system, is proposed. In the system, the forces among the parts are transformed to spring stiffness broken lines, and relative positions of the key parts are described by the relative maximum displacements, which are taken as the parameters in the optimization. Multi-objective optimization is applied in the concept car layout, and the objectives are the acceleration and so on. The overall optimal lay out of the vehicle structure is obtained by parameter iteration. The feasibility of the proposed optimization method is proved by simulation of a concept vehicle lay out example.

In order to study the instability caused by engine braking during turning of high-speed vehicles, the engine braking torque was introduced to obtain its analytical expression, and the 5D nonlinear equation of the vehicle system was established. Numerical simulations of the turning of high-speed vehicle with engine braking and without engine braking were carried out to study the dynamic characteristics of the high-speed vehicle turning. Simulation results verify the rationality of the proposed vehicle model. Besides, it is revealed that the engine braking torque will cause the instability of the high-speed turning vehicle. The Poincare section of phase trajectory and the power spectral density were used to validate that the instability motion caused by engine braking is chaos motion.

Three possible instability sequences in vehicle combinations were obtained by using graph theory and the link relationship of each unit of the vehicle. A multi-body dynamic model, including nonlinear tire model of the vehicle combination was established by TruckSim. By simulation of the change of the state variables of each vehicle unit under high-speed step response, it was obtained that the main factor to influence the instability of the vehicle is the roll rate. Combining with the energy equation, the maximum energy of each vehicle unit under different vehicle speed was calculated, and the instability sequence of the vehicle units was obtained. Meanwhile, verification and energy analysis were carried out for the sequence of possible instability obtained by graph theory.

Expressway traffic state is divided into unimpeded, slight smooth and congested sub-states by fuzzy C-means clustering method. Combining expressway second-order macroscopic traffic flow model with particle filter algorithm, the traffic state parameters are estimated. By clustering the estimation values of the parameters to one of the three kinds of traffic sub-states, the corresponding traffic state estimation is obtained. Based on the traffic state estimation and the characteristics of each traffic sub-state, an expressway joint control model is established, which combines variable speed-limit control and on-ramp control. The traffic data of Changchun East-expressway is used to validate the model. Results show that the total time spend of the expressway is reduced by 4.55% and the traffic flow density is also reduced. The traffic congestion is eased to certain extent.

Based on passenger experience, the bus running time stability index and its calculation model were proposed. The evaluation index can reflect the performance of bus lane and the passengers' interests. It is suitable for evaluating the bus operation reliability. An on-board survey on representative bus lines on road-side bus lane in Shnaghai was conducted. Based on the survey data, the relationships between bus running time stability, intersection delay caused by traffic signal and the length of road-side bus lane were obtained by regression. The impact of the length of road-side bus lane on bus operation reliability was analyzed. Finally, the length of road-side bus lane was suggested no less than either 6.5 km or 40% of the total line, which can provide theoretical foundation for the design of bus lane in China.

Taking pedestrians' crossing behavior as the research object, the quantified method of the conformity effect is proposed. The evolutionary game model of pedestrians' crossing behavior under the influence of conformity is constructed. Furthermore, the pedestrians are classified into adventurous, compromise and conservative groups, and a simulation experiment is designed. The results show that the constituent of pedestrians and the proportion of illegal crossing groups have significant influences on the pedestrians' crossing process. At last, an improvement strategy of the social force simulation model considering conformity effect is proposed. The results of this research can enrich and expand the theoretical framework and analytical methods of pedestrians' behavior, and provide reference for setting parameters of pedestrian simulation.

Aiming at the problem of high sensitivity to iteration initial guess when using Newton-Raphson iteration method to compute the forward kinematic solution of orthogonal Stewart-6D- platform, a compensation method based on Levenberg-Marquardt (L-M) algorithm of back propagation model iteration initial guess was proposed. The adaptation, the output prediction and error performance of the proposed algorithm were analyzed in comparison with the back propagation model based BFGS quasi-Newton algorithm, back propagation model based scale conjugate gradient, back propagation model based gradient descent with adaptive Ir algorithm. With the help of inverse solution model based Simulink and SolidWorks, successful training samples were established. 1000 groups of data were randomly and comprehensively picked up. 900 groups were used for training the net and the other 100 groups were used for testing whether the trained net is qualified. Simulation results show that the initial guess modified L-M algorithm of back propagation model was significantly calibrated. The convergent speed of the iteration modified algorithm was improved. The angle and displacement calibrating error rate was less than 0.1%. The test results of the improved BP Neural net can meet the requirement.

In this paper, a 3D CFD model of the combustion process inside the cylinder of GDI engine is established and simulation is carried out to analyze the effects of the injection phase and ignition phase on the stratified charge combustion of the engine. The method of indicator diagram is adopted to compare the experimental results with the simulation results, which are in good consistence. By comparing the effects of the injection phase and ignition phase on the stratified charge combustion process and emission, the best fuel injection phase and ignition phase are obtained under specified condition. The method can also be used to calibrate the best injection phase and ignition under other conditions.

Based on a 1.4 L tumble-intake-port gasoline engine, the refluent exhaust gas stratified distribution status and combustion performance improvement with different control parameters of the exhaust valve secondary open were studied using 3D computational software FIRE,and the simulated regularities were verified by optical measurement. The simulation results show that refluent exhaust gas forms basically homogeneous distribution in the combustion chamber with exhaust valve secondary open earlier at intake stroke.While,the exhaust gas forms evident stratified distribution with fresh charge after the formation of intake swirl at later intake stroke.Longer exhaust secondary open duration leads to higher EGR rate and weaker tumble intensity,which is able to reduce over-rotated exhaust gas.Refluent exhaust could not take full use of the fresh charge flow with higher exhaust valve secondary open lift,so the gas is easily diffused to the center of combustion chamber.Refluent gas could reduce the adverse effect of EGR on combustion from the aspects of EGR stratified distribution and thermal effect.Regardless of the knock possibility,stratified exhaust gas temperature at 850 Kelvin condition,the cylinder pressure peak is 51.4% higher and the heat release peak is 91.4% higher than that at 298 Kelvin condition with the same exhaust valve secondary open duration 70~180 °CA ATDC and max lift of 5 mm. meanwhile, the cylinder pressure peak and heat release peak of stratified exhaust gas at 298 Kelvin condition are 79.8% and 147% higher respectively than that in EGR homogenous distribution case with the same gas mass.

On the basis of geometric layout of the timing chain system of the automobile engine, the influence of the lag angle of camshaft on phase change of the timing chain system is studied, and the constraint conditions of the timing chain wear limit elongation are put forward. According to the working condition of high speed, variable speed and variable load, the reliability test rule of the actual loading chain of the engine is designed. The rule also covers the sprocket and chain meshing impact. The idle speed and alternating load simulation tests of the domestic timing chain system and the MORSE timing chain system are carried out on a positive timing chain system simulation test bench. Results show that the initial wear is about more than 1/4 of the total wear elongation, which indicates that controlling the manufacturing precision of the parts and ensuring the assembly quality can significantly improve the service life of the timing chain. Meanwhile the dynamic response characteristics of tension the device are the key factors to improve the timing chain system dynamic characteristics.

The ordinary integral two-stage relief valve can not work steadily when its dimension is limited. To solve this problem, a mathematical model of two-stage relief valve is established and the stability criterion of the pilot valve is obtained. The criterion indicates that there is a matching relationship between the main valve size and the pilot valve size in integral two-stage relief valve. If the main valve size is too large or the pilot valve size is too small, the pilot valve will become unstable. A new type two-stage relief valve with a series damping orifice in the front chamber of pilot valve is proposed to achieve stable control of the pilot valve and main valve without increasing the volume of the relief valve. This damping orifice can avoid direct impact on the pilot valve core from the pilot input flow, and decrease the open loop gain of the pilot valve loop. Theoretical and experimental results show that the new type two-stage relief valve can work steadily and has a better pressure-flow characteristic with the extreme small size.

The spatial geometric error of hybrid serial-parallel machine tool is modeled and investigated. This synthesis error model is based on multi-body system and the consideration of the combined effect of positioning errors, straightness errors, squareness errors and angular errors of each axis. With substantial data measured by laser interferometer, the distribution maps of some errors are drawn. By choosing a planned curve on the surface of workpiece and moving each axis with errors, the spatial geometric error appears and is illustrated on Matlab. Further, by decomposing the spatial geometric errors along each axis of spatial coordinate and comparing with position errors of the corresponding axis, a conclusion is drawn that both errors have close value and the same distribution trend. The positioning errors have the greatest impact on the synthesis error, followed by the straightness errors. The impact of the angular errors on the synthesis error can be ignored.

A structure's temperature-related dynamic testing system of a Micro-electromechanical System (MEMS) was built. This testing system consists of high impact loading system, temperature loading system and high-speed photography system. Using this system, the dynamic characteristics of fuse MEMS setback arming device was tested under temperature and impact load coupled environment. The relative displacement-time curve and velocity-time curve between slider and baseplate of the MEMS setback arming device were obtained at different temperatures (-40 ℃~ 50 ℃). Through the comparative analysis of the curves, the effect of the temperature on the relative displacement and velocity between the slider and baseplate of the MEMS setback arming device under impact load condition was obtained.

To study the effect of resonant cavity on the standing wave levitation device, four different kinds of standing wave levitation simulation model with different resonant cavities are established. The acoustic pressures of the four levitation models with no resonant cavity and with different resonant cavity radii are analyzed by ANSYS. It is found that, under certain condition, the addition of resonant cavity to the standing wave levitation device can increase its levitation ability, while under other condition it can also reduce the levitation ability. When the resonant cavity radius is slightly larger than the reflect end face radius, the increase rate of the acoustic levitation force is maximized. An experimental platform of concave-concave standing wave levitation was set up. The experiment results are consistent with theoretical analysis results. When the resonant cavity radius is 1.023 times of the wave length, a 6.5 mm diameter steel sphere can be suspended, while when the resonant cavity radius is 1.251 times of the wave length, a 5.5 mm diameter steel sphere can not be suspended by the device.

According to the theories of differential geometry and the gear engagement principle, this paper analyzes two kinds of composite transmission form of curve-face gear pair. The motion law is verified by ADAMS simulation. The force condition of the composite motion of the curve-face gear pair is analyzed and calculated, and the change state of the pressure angle of the gear pair is also obtained. An experiment platform is built to verify the motion law, and laser displacement sensor is used to measure the displacement of the gear pair. It is shown that the calculation results are in consistence with the theoretical analysis results and the simulation results, which validates the calculation method.

The performance of bearing cage has great influence on the bearing working situation under the conditions of high speed and heavy load. The problem of cage may result in temperature rise due to friction in the contact area and even lead to bearing failure. To solve the key problem, a new structure 7014 angular contact ball bearing with side beams of polyetheretherketone (PEEK) cage is compared with the traditional bakelite cage. Two models are established using finite element method, and the numerical simulation is verified by bear temperature rise experiments. Using Fluent, the influence of the new structure of PEEK cage on the bearing airflow field, and the influence of the new material property on the bearing temperature field are studied. Finally, the PEEK cage is verified to have a good working performance.

A new technical approach is proposed for the reliability analysis of CNC machine tools system under the failure correlation. First, the component reliability models were built based on related failure mechanism analysis. Then, taking the component reliability models as the marginal distribution, the system joint reliability function was developed with the introduction of the Copula function. Third, the parameter of Copula function was estimated with the aid of Kendall rank correlation coefficient obtained from samples. Finally, a case study of machining center is carried out. Comparing with the component reliability series model and with the traditional Copula function model, the new Copula function model considering failure correlation directionality is ore rational and effective.

Considering the high-dimensional non-linear performance functions of complex structures, a new structural reliability analysis method based on dimension reduction algorithm was proposed. The n one-dimensional approximate functions were established to substitute the n dimensional performance function by using dimension reduction algorithm. With the help of Taylor series and statistical moment theory, the first four order moments of the performance function were solved. The cumulative distribution function of the performance function was fitted by Edgeworth series and the failure probability of the structure was obtained based on the reliability theory. Compared with the traditional methods, the new method does not need to use integral method to solve the statistical moments of the performance function, and not need to search the most possible failure point iteratively. Numerical results indicate that the proposed method has high precision and good adaptability.

The dispersion characteristic of guided wave in composite plate with fiber fracture damage is analyzed using strip element method, in which the different damage patterns are considered. The layer with fracture damage is assumed to have the same elastic constants as the substrate. Taking each layer as a strip element, the equation governing the movement of a single layer is constructed. Through assembling the governing equations of all layers, the global movement equation of the composite plate with fiber fracture damage is obtained. Rewriting the global equation yields the corresponding eigenvalue problem, which can be used to calculate the relationship between the guided wave frequency and wave number in the plate. Finally, the influence of different damage patterns on the dispersion characteristic of guided wave is investigated by numerical examples. The results may provide theoretical basis for non-destructive evaluation of damage in the fiber-reinforced composite plate via ultrasound technology.

Based on Abaqus/Standard software, the finite element model and hybrid algorithm for multi-point 3D stretch bending profile of aluminum alloy were established. The dynamic explicit algorithm was used in stretch bending, and the static implicit algorithm was used for spingback prediction. The stress, strain and springback of the part were simulated by implicit method of Abaqus/Standard software. The forming experiment results valid the finite element model and the hybrid algorithm. The springback deviation between theoretically predicted value and the measured value decreases as the bending deformation increases in the vertical direction.

The inelastic recovery behavior of DP780 steel was studied in continuous cyclic loading-unloading tensile tests. The composition of springback and the percentage of inelastic strain recovery of the steel were determined. Then, a mathematical model of unloading modulus and plastic strain was proposed. The model was verified by numerical simulation and experiment. It is shown that the plane anisotropy of DP780 steel is not obvious. The unloading and loading paths constitute a closed loop, which is formed due to the nonlinearity of the elastic modulus in the unloading and reloading cycles. With the increase of the pre-strain, the elastic modulus decreases rapidly, which then increases slowly and gradually tends to be stable after the pre-strain reaches 6%, the unloading elastic modulus decreases by 17%. The total unloading strain recovery is composed of elastic strain recovery and inelastic strain recovery, and the inelastic strain recovery can reach as high as 11% of the total strain recovery. The microstructures of DP780 steel were detected by SEM and TEM, and the microscopic mechanism of the inelastic recovery was revealed. It is shown that the plastic deformation and austenitic phase transformation cause the increase of dislocation density; the martensite dislocation moving obstacles lead to a large amount of dislocation pile-up and the movable dislocation bending, increasing the length of the dislocation line and additional elastic deformation. This results in significant inelastic recovery behavior. Integrating the model to the finite element simulation improves the accuracy of simulated springback and the mold springback compensation is more accurate.

A novel checkpoint mechanism is presented that can support stream data processing and online dynamic adjustment of the checkpoint period. First, for the data flow burst, we propose a recovery time model to provide guarantee for the recovery time. Then, depending on the real-time variation of workload, we provide a real-time cost model for checkpoint. Finally, the peak traffic avoidance protocol can dynamically choose the best checkpoint time by updating the real-time cost of checkpoint periodically. Experiments show that, compared with existing methods, our self-adaptive mechanism has obvious advantages in flexibility and real time, and it is able to meet the requirements of high reliability and real-time fault tolerance in stream data processing.

Deterministic replay plays an important role in debugging parallel programs. In parallel program design, recording share memory access has become a light spot, according to great non-determinism brought by multithreading memory interleaving. Previous research focused on fine grained instrumentation of memory access instruction, or kernel modification, or special hardware extension to record shared memory communication. However, these methods have the problems of runtime overhead cost and awful potential safety hazard. This paper proposes an efficient deterministic replay technique employing page-protection mechanism on commodity hardware platforms and operating system. Furthermore, this work deeply analyzes the runtime overhead incurred by the proposed technique, and puts forward several optimization strategies of private-lock mechanism, private heap memory pool and initiative page-preemption algorithm to promote the performance. Our prototype UPLAY is implemented on Linux. Performance evaluation shows that the record slowdown is only 9.26X and is much smaller than prior user-level replay system.

Searching for Approximate Nearest Neighbors (ANN) of high dimensional floating point data has to compute their expensive Euclidean distances, and the memory occupancy rate is high. In order to fix such problem, an algorithm is proposed to effectively and efficiently map high dimensional floating point data into low dimensional binary codes, while preserving the normalized distance similarity. As a result, Hamming distances can be used to instead the Euclidean distances during ANN search process. To guarantee the ANN search performance of obtained binary codes, the distribution adaptive binary labels of the training data are firstly acquired based on the look-up mechanism. Then, the classifaction planes are obtained on the basis of SVM algorithm, and the one with the highest entropy value is chosen as the final hashing function. In order to further improve the retrieval performance, the retrieval system based on multiple binary codes is proposed. During the training process, different kinds of original encoding centers are chosen to obtain multiple hashing functions and multiple binary codes. During the search stage, the points with the minimal average Hamming distances are returned as query results. Experiments show that the proposed algorithm can efficiently and effectively map the floating point data into superior binary codes, and has excellent ANN search performance when compared with other state-of-art methods.

In order to improve the parallelism of pessimistic lock mechanism, an optimistic lock protocol was designed and applied for modifying the original lock mechanism in Zookeeper. By studying the mechanism of distributed lock and the working principle of Zookeeper, the execution time was decreased by the optimistic lock protocol. Theoretically compared with three other protocols, the optimistic lock protocol is the most optimized. Based on ensuring consistency maintenance, the optimistic lock protocol possesses mutual exclusion, non-deadlock and fairness. Simulation results show that the optimistic lock protocol significantly improves the data access performance, and outperforms the other lock protocols in execution time and bandwidth occupancy.

In order to acquire high quality image information through infrared detector with low resolution, a method for acquiring image sequence through a Micro-scanner Imaging (MSI) system and Super-resolution Image Reconstruction (SRIR) algorithm was investigated. First, the working mode, hardware and software composition of the MSI system were elaborated. Then, the method for acquiring the image sequence from the MSI system based on motor drive was extracted. Finally, an algorithm of Projections onto Convex Sets (POCS) based on dictionary learning was presented, which was used for SRIR. To validate the proposed method, low resolution image sequence was acquired from digital simulation and real shooting. Experimental results indicate that the proposed method could effectively restore the edge information of an image and suppress noise.

Based on the idea of clustering method by fast search and find of density peaks, we put forward an overlapping community detection method based on density peaks. In the proposed algorithm, first a new distance matrix is defined to overcome the defects of adjacency matrix being filled with integers. Then, the probability form is used to depict the possibility of each node that belongs to different clusters. The experimental results on real network show that the proposed method performs very well.

First, the saliency is extracted from the original image based on visual attention model. Then, the image is decomposed by Non-negative Matrix Factorization (NMF) to reduce the dimension and scrambled by chaotic encryption. The decomposed saliency map is embedded into the frequency component of the original image by DCT-SVD transform. At the receiving terminal, the watermarking is extracted from the received image, and the saliency map of the received image is also extracted. Finally, comparison of the difference between the received image's saliency map and watermarking, the Lorenz curve and the reasonable threshold are used to determine whether the received image is changed by noise or artificial tampering. Compared with other similar algorithms, the proposed algorithm has good discrimination against noise interference and artificial tampering.

Current thresholding algorithms for image segmentation are sensitive to noise. To overcome this problem, a new Otsu thresholding algorithm is proposed based on image decomposition. The whole segmentation algorithm is designed as an iteration procedure. In each iteration the image is segmented by the 3D Ostu, and then it is filtered by Gaussian kernel filtering to get a smoothed image, which is taken as the input of the next iteration. Finally, segmentation results obtained in the iterations and are pooled to get final segmentation. The advantages of the proposed algorithm are that its segmentation results are stable and it is robust to noise. Experiments on medical MR brain images are conducted to demonstrate the effectiveness of the proposed method. Results indicate that the proposed algorithm is superior to other thresholding algorithms.

Directional Sensor Network (DSN) node with stability of omnidirectional perception plays a decisive role in network coverage. Using the optimization method of SNOPT, the dimensions and shape of enhanced ultrasonic transducer were optimized first. With optimized horn the directivity was promoted obviously and the radiated sound pressure in the central axis was 3.5 times bigger than that of normal transducer. Then a new rotational circumferential scanning program of single-beam was designed based on the enhanced ultrasonic transducer. The model of the highest scanning speed for ultrasonic ranging was built, and the highest scanning speed of 253 r/min was achieved for monitoring the target in 6 m away. In order to get stabilized prospecting effect, the matching relationship between scanning speed and pulse frequency was established for constant number of ultrasonic beams in one scanning period. At last, target acquisition rate was analyzed. Calculation results demonstrate that the highest speed of the ultrasonic circumferential scanning system is 215 r/min in the case of good compatibility, which can acquire the target with a speed lower than 65.5 km/h.

To estimate the Direction of Arrival (DOA) of coherent signals accurately and quickly, a new decorrelation method based on spatial smoothing technique and eigen space multiple signal classification (MUSIC) is presented. After spatial smoothing of the coherent signals, the eigen space MUSIC algorithm is applied to estimate the DOA in order to make maximal use of the information of signal and noise subspaces. In addition, the DOA estimation of uncorrelated signals is not affected, as well as the power of signal sources can be estimated effectively, which can improve the probability of success in the estimation of low power signals. The proposed method possesses a better resolving ability and a lower SHR threshold than conventional spatial smoothing technique and modified MUSIC algorithm for DOA estimation of coherent signals. The simulation results demonstrate that the proposed method is effective and robust in DOA estimation.

To resolve this problem, first, the procedure of the speed recording is analyzed and a recording device fingerprint based on device noise is proposed. Then, a noise estimator including two noise estimation algorithms is applied to acquire sufficient device noise. Finally, to evaluate the effectiveness of the proposed device fingerprint, five classification techniques are utilized to identify the source recording device. Experiments are carried out on two corpora. One corpus comprises speech recordings obtained by 22 recording devices coming from four types of common recording devices, and the other corpus consists of speech recordings from 21 cell phones. Experiment results verify the effectiveness of the proposed method.

To solve the problem that tracking algorithm may lead to drift or failure due to the accumulated error under the occlusion environment, a Multiple instance learning based Fragment Tracker (MFT) is proposed. In this MFT, the random ferns is used as the basic detector. To improve the adaption of the target change and the precision of the learning, the multiple instance learning is introduced to online update the detector. The object is segmented into fragments and parts of them are selected as the candidate set. The candidate block is tracked by the corresponding detector. The object can be finally located by the selected blocks. A real-time valid detection is made for the candidate blocks and the invalid block is replaced with an appropriate block to improve the robustness of the tracking. Experiments on variant challenging image sequence in the occlusion environment were carried out. Results show that, compared with the state-of-art trackers, the proposed MFT solves the problem of target drift and failure efficiently and has higher accuracy and better robust.

At present, the space intersection acoustic localization algorithm based on Time Difference of Arrival (TDOA) only uses a simplex localization method. We herein propose an acoustic localization algorithm based on region division. In this algorithm, we set four spatial six-element arrays, confirm the array parameters based on the principle of minimizing the mean value of area errors, and then divide such area into 16 sub-regions, to each of which we apply different localization algorithm. With fireworks as the sound source, we randomly selected three sound source points in a plot in suburban of Beijing with area of 200 m × 200 m, and carried out repeated experiments for three times at each point. The localization errors at the three points are all less than 1 m.

In the process of image feature extraction, the image processing technique is applied to the speech recognition. First, equal width zoning line projection and binary width zoning line projection are carried out to the spectrogram, which are taken as the spectrogram of the first characteristic set and the second characteristic set, respectively. Meanwhile, equal width zoning line projection is carried out again to the spectrogram after Fourier transform, treating as the third feature set. Then, the above three feature sets are used as feature vectors to Support Vector Machine (SVM) as a classifier for the overall recognition of specific two words Chinese vocabulary. 1000 voice samples are used in simulation experiment. The results show that the correct recognition rate of this method is 92.8%, and it provides a new way of thinking of Chinese vocabulary overall recognition.

In order to solve the mutual interference problem among homogeneous peaks in Time-of-flight and Mass Spectrometry (TOF-MS) quantitative analysis, a spectral peak separation method was presented. First, according to the technical characteristics that those spectral peaks with close mass number have close shape, the peak positions were determined by the correlation algorithm between Gaussian curve and the original mass spectrum. Then, the individual single peaks were selected by the principle of “high amplitudes kept and low amplitudes left”. The characteristic peak was obtained by stacking and normalization of the single peaks. The power spectral density function was constructed by the characteristic peak, and positions and amplitudes of the overlapped peak were determined in accordance with the minimum principle, thus achieving the overlapped peak separation. The result obtained by the above characteristic peak matching method was compared with the results of Gaussian matching method and Lorentzian matching method respectively. When dealing with symmetric peaks with δ= 0.2, these results are basically consistent. However, when dealing with asymmetric peaks with δ= 1.6, the effect of characteristic peak matching method is much better than the other two methods. Experimental results show that the presented method can be used to separate the ²⁹Si and ²⁸Si¹H overlapped peak, the separation resolution is improved from 0.371 to 0.519, while the original shape information of the peeks is maintained.

In order to satisfy the requirement of focusing accuracy of modern Secondary Ion Mass Spectrometer (SIMS)'s zircon sample image auto focusing system, an algorithm that automatically removes noise is proposed and applied to the Time-of-Flight (TOF)-SIMS. The proposed algorithm includes zircon image recognition and segmentation, a secondary-type focusing algorithm, and a focusing control strategy. A Roberts function and a differential accumulation focusing control strategy are used for coarse tuning in area far from the peak. In the near-peak region, the zircon image is captured and segmented from the background. A local coordinate function and hill climbing method are then used for fine tuning. A series of experiments show that the proposed algorithm has an accuracy rate of 99% and can effectively restrain noise interference, enabling the automatic focusing of zircon sample images.

In order to accurately measure the geomagnetic field around an underwater vehicle and improve the precision of geomagnetic aided navigation, a spatial difference measuring method is proposed based on multi-sensor. First, a new measurement model of magnetic vector sensors is established by analyzing the magnetic field types and the spatial distribution characteristics around the vehicle. Then, the spatial difference model expression is deduced according to the characteristics of interference magnetic field and its coupling relationship with the magnetic field. The proposed method was compared with traditional method by simulation and ground experiment. Results show that the proposed method can obviously restrain the impact of the interference magnetic field. When the intensity of the outside interference magnetic field is 1000 nT, the measurement error can be controlled under 150 nT by the spatial difference measuring method, which is able to improve the ability of anti-jamming in geomagnetic field measurement.

A new Double-V-shaped (DVS) furrow opener was designed to further insure the operation of soybean ridge cultivation precision planting, improve the sowing quality and sowing depth uniformity. The opener consists of shovel stand and profiling press mechanism. The performance of this opener was experimentally studied in soybean fields. The opening depths were set to 40 mm, 50 mm and 60 mm respectively, and working speeds were set to 1.9 m/s, 2.2 m/s and 2.5 m/s respectively; the sowing Depth Variation Coefficient (DVC) and sowing Width Variation Coefficient (WVC) were measured as the indexes. Experimental results show that the SVS furrow opener can smooth the furrow cliff, improve the sowing quality and decrease both DVC and WVC. The minimal DVC was 0.086 when the furrow depth was 40 mm and working speed was 1.9 m/s, and the minimal WVC was 1.356 when the furrow depth was 60 mm and the working speed was 1.9 m/s. Optimization analysis of the experimental data using Design-Expert software shows that the working quality of the cooperation of double-disk digger and DVS furrow opener is better than that of the DVS furrow opener. The best operation condition is at 1.9 m/s working speed and 57 mm opening depth, where the DVC is 0.15 and WVC is 1.25.

Experiment results show that when PC12 cells were exposed to 20.00 μg/mL genistein (GEN), daidzein (DAI) or their combination (GEN-DAI), the cells' viability rates, mophologies, mitochondrial membrane potential, superoxide dismutase activities and inhibition rates were not changed. However, different changes of PC12 cells were observed under different treatments. The reactive oxygen species level, the relative fluorescence intensity and malondialdehyde of PC12 cells were increased by GEN. The leakage rate of lactic dehydrogenase was decreased in DAI and in GEN-DAI combination treatments, the glutathione contents were increased to (297.27±9.47) μmol/(g·prot) and (269.90±00) μmol/(g·prot) respectively. The acetylcholine content in culture medium and metabolism of cholinergic system was increased in GEN-DAI treatment. GEN-DAI combination treatment can more significantly increase the activity of the antioxidant system of PC12 cells than GEN and DAI treatments.