Based on the strength of state feedback, a H_∞ robust control approach for integrated chassis system is proposed. The two degrees of freedom vehicle model is employed as a simplified model of the controlled object. This control approach is used to coordinate the active front wheel steering system and the direct yaw moment control system. The direct yaw moment control system is based on the inverse operation of HSRI tire model and PI control. Two typical cases, J-turn and sine with dwell, are simulated. Results show that the proposed H_∞ robust control approach for integrated chassis system has good control effect, and can significantly improve the handling and stability of the vehicle.

Robust design of powertrain mounting system is researched to improve the robustness of the system under uncertain stiffness property of the mount. Global optimization algorithm and parallel computation technique are employed to improve the computational efficiency. The motion equations of the system are built in crankshaft axis system, torque roll axis system and vehicle axis system. Modal formulation is presented for each excitation in a specific axis system. A design procedure is proposed. In this procedure global optimization algorithm is employed to search feasible region first; then the feasible region is divided and distributed into each computation core; finally, parallel computation technique is used to carry out robust evaluation. A robust optimization model is formulated based on a powertrain mounting system and optimization is carried out according to the proposed design procedure. Results indicate that the robust mean value of decoupling ratio has a little variation from the deterministic one, but the robust standard deviation is obviously smaller than the deterministic one. Especially for higher uncertain level, the robustness of the system is significantly improved.

A mathematical model of divided steering linkage for electric vehicles is built and validated. Aiming at minimizing the difference between Ackerman steering angle and the practical steering angle, a robust optimization method is proposed based on theory and Monte Carlo simulation. The constraints are deduced by the characteristics of the steering linkage. The influences of uncertain factors on the optimization results are analyzed. The results demonstrate that the optimal linkage has a better Ackerman performance, and the robust design shows better reliability against the uncertain factors.

Linear seat suspension has poor isolation ability of low frequency vibration. To improve the low frequency vibration isolation performance of off-road vehicle seat, a nonlinear seat suspension is designed based on spherical roller mechanism. The quantitative relationship between the main design parameters and the force-displacement characteristics is established, and then the main parameters are identified. Based on ADAMS method and test, the force-displacement characteristic and isolation performance of the nonlinear seat suspension are tested. Results show that the designed suspension has high static stiffness and low dynamic stiffness characteristics, and the lowest isolation frequency is lower than that of traditional linear seat suspension. However, the internal friction can affect low-frequency vibration isolation, to which attention should be paid in the suspension design.

To eliminate the hysteresis characteristics of proportional relay valve and its influence on heavy vehicle braking performance, the response time and hysteresis characteristics of the proportional valves were tested. A vehicle dynamic simulation platform was developed using MATLAB/Simulink and AMESim for the purpose of Electric Braking System (EBS) control strategy development and braking performance analysis. The platform consists of pneumatic EBS components and it can reflect the EBS performance. A hysteresis compensation method, which integrates PID closed loop control and the feedforward compensation control, was proposed for mitigating the hysteresis characteristics of the proportional relay valve. Experiments were conducted on the simulation platform to evaluate the effect of the control strategy on the valve characteristics and vehicle braking performance. Results show that using the proposed pressure control strategy the pressure response of the proportional relay valve is advanced by 76% and the static hysteresis is almost eliminated. Meanwhile, the braking distance is reduced by 2.8%.

An integrated electro-hydraulic brake system was proposed, and the coordinated control strategy of regenerative braking force and hydraulic braking force was studied under non-emergency/emergency braking conditions. The principle of the electric-hydraulic brake system with an integrated master cylinder was analyzed, and the basic control strategy for the two braking conditions was proposed. Brake force distribution strategy between regenerative braking force and hydraulic braking force under non-emergency condition was investigated. Two cases triggering the anti-lock braking system were presented. Cooperative control between electric-hydraulic brake and anti-lock brake using hydraulic braking force was studied with simplified control logic. Hardware-in-the-loop test bench was built using xPC target, and non-emergency/emergency braking tests were carried out. Test results show that the proposed integrated electro-hydraulic brake system and braking force cooperative control strategy can meet the braking energy recovery and coordination with the anti-lock brake control needs.

Test diagnosis, analysis and improvement of a SUV and its air conditioning system are carried out to solve the inner noise problem, which is generated while the air conditioning is turned in idle. The test frequency spectrum analysis of inner noise and compressor vibration, modal analysis and test validation show that the working frequency of the compressor is close to the system's first order frequency. This causes resonance, which leads to obvious noise difference between turning on and turning off the air conditioning in idle. To solve this problem, the shape of the compressor support is improved by topology optimization. Modal analysis indicates that the first order modal frequency of the improved support keeps away from the working frequency of the compressor. The improved support is test and the results indicate that the inner noise is reduced by 2.3 dB(A), and the noise decreases obviously when the engine speed is from 900 r/min to 3000 r/min in run up condition.

A twin-tube hydraulic shock absorber F-V model is proposed based on structure parameters. First, a finite element model of the shock absorber rebound valve plate is established, and the load versus valve deflection curve is obtained with the model. The relationship between flow rate and pressure variation is then calculated. Then, this curve is integrated into the shock absorber model. The comparison between the model output and experiment data demonstrates the high accuracy of the proposed model. Finally the influence of the structure parameters of the rebound valve on the damping performance is analyzed through simulation.

To solve the time-to-line-crossing (TLC) prediction problem during lane change process, the geometrical motion feature of vehicle during lane change was analyzed and a yaw angle estimation algorithm between vehicle and lane mark was proposed. Based on this, TLC prediction models for straight and curve roads were established. A test platform was developed which consists of vision sensor, vehicle gyro and onboard CAN bus data capture card. Real-road driving test of several drivers was carried out, and representative data of lane change state were collected. The TLC prediction models were tested using the real lane change data. Results show that 87.0% prediction errors on straight road were less than or equal 0.1 s, and the corresponding rate on curve road was 93.7%. The prediction errors of two models meet the normal distribution.

A crushing model of rectangular section thin-walled beam filled with aluminum foam is proposed based on the theory of hollow rectangular section beams. The influence of the aluminum foam on the effective crushing length and the interaction between the foam and the thin-walled beam in crushing are considered in this crushing model. The average crushing force is composed of three parts, the modified hollow beam crushing force, the aluminum foam crushing force and the interaction force between the foam and the beam. Experiment data of mild steel and aluminum thin-walled beams filled with aluminum foam are adopted to validate the proposed crushing model. It is shown that the theoretical results are in good agreement with the experiment results.

The release characteristic of the separate dual left-turn lanes on the signalized intersection was researched. Lane usage characteristics and saturation flow rate characteristics were analyzed using probability theory and mathematical statistics. Using video image processing technology, the space and space-time travel characteristics of separate left-turn vehicles were described and analyzed within the intersection. There was interference between the two flows that traveling within the intersection. The result of this investigation may provide a theoretical basis for the design of separate dual left-turn lanes and optimization of signal-timing.

To estimate the intersection queue length, a magnetic sensor is deployed near the stop line at the intersection. Through the vehicle queue mechanism modeling, the evolution of vehicle occupancy sensor time and the departure interval can be obtained. Eventually, the queue length of the last signal cycle can be estimated. This paper analyzes the variance of vehicle occupancy sensor time and the departure interval with the increase in queued vehicle number, thereby proposes departure interval model, vehicle occupancy sensor time model and comprehensive model to estimate the queue length. The accuracies of the proposed models are compared using field experiments. Results show that the proposed queue length estimation method can accurately get the queue length of the last signal cycle. The method costs low and can be deployed easily, and thus, it can facilitate large-scale popularization and application. It can provide intersection queue length information for signal cycle optimization and traffic service level evaluation in road signal intersections.

A space occupancy estimating method based on remote sensing images is proposed.First,Hough transform is used to estimate the length of the road.Then, fuzzy processing technique is applied to estimate the length of vehicles.Finally, the vehicle space occupancy is estimated.Simulation experiments are carried out using OpenCV under VC+ +6.0 environment. Simulation Results show that the proposed method can accurately estimate the vehicle space occupancy on the road.

In this paper, a probability detour path choice model and a traffic state updating model were established, considering the influence of traffic guidance information on car drivers' route choice at intersection. These models were considered as two important constraints. Then, an optimal signal timing model was built under the coordination control of traffic guidance and bus priority. An improved genetic algorithm was applied to solve the optimization model. Results show that the total passenger delay, vehicle delay and the exhaust emissions per capita are reduced by 4.1%, 2.8% and 1.4% respectively after considering the influence of traffic guidance information. It is certified that the goals to reduce the overall traffic network load and vehicle exhaust can be achieved to certain extent by reasonable traffic guidance.

A strategy to turn the steering wheel uniformly while parking is put forward to design a parking path with more consistency and fewer calculations. First, the trajectory of the center point on rear axle is deduced while the vehicle is driven at low speed and the steering wheel is turned uniformly. Second, the parking process is divided into five stages and the parameters of the optimized path are obtained according to obstacle avoidance. Third, the vehicle speed control system based on the PID closed-loop feedback theory is designed, and experiments show that the real speed matches the expected speed. Fourth, the signal of the torque sensor needed by EPS controller is simulated by parking controller; then the steering wheel rotational speed control system is designed, and relationship between the torque and rotational speed is obtained by system identification. Experiments show that the degree of fitting between torques given by system identification and real torques is above 96%. Finally, the change of vehicle speed, rotating angle of the steering wheel, accelerator and brake of two segment parking and five segment parking are obtained. Comparison of two segment parking and five segment parking shows that five segment parking has higher consistency.

In order to accurately calculate the stress and displacement of composite beam under load, based on the elastic mechanics and contact theory, the finite element solution of the beam is derived, in which the effect of shear slip is considered. Using the finite element solution, the deflection and interface shear slip under concentrated loads are calculated. The calculation results are in good agreement with experimental results, which verifies the accuracy and reliability of the finite element solution. This finite element solution provides a new computing tool to analyze the stress and deformation of composite beams with shear slip.

In order to reveal the mechanisms of natural vibration frequency of simply supported beam reinforced with eccentric prestressed tendons, a calculation method of the natural frequency is proposed, and the influence of effective prestress on the natural frequency is analyzed. First, the vibration system of the simply supported and prestressed beam is decomposed into two subsystems, the prestressed tendons and the simply supported beam. The dynamic equilibrium equations of the two subsystems are established using the principle of structural vibration. Then, based on the coupling analysis and processing of the vibration equations of the subsystems, a calculation method of the natural frequency of beam is derived. Using this method, the calculated natural vibration frequencies of the simply supported and prestressed beam are in good agreement with that predicted by finite element method.

To reduce the fatigue life prediction error of steel structure using traditional fatigue prediction algorithm, the interval-probability reliability analysis method was presented to deal the fatigue life prediction of steel structure with the consideration of variables uncertainty. The parameters of the linear accumulative damage model and the crack propagation model were distinguished as probabilistic variables and interval variables based on previous studies. The theoretical foundation was established by the consistency relationship between the interval reliability and the probability reliability model with lognormal distributed variables in theory. The solving process was combined with definition of interval reliability index and the probabilistic algorithm. The results of typical fatigue details of actual bridge show that, when the variable coefficient of the stress amplitude is in the range from 0.25 to 0.35, the results of the interval-probability analysis are more conservative than that of traditional probability method.

A heat balance mathematical model of the hydraulic system of loader was established according to the heat generation and heat dissipation characteristics of the main components. Dynamic simulation model of the working equipment and thermal system co-simulation model were built based on ADAMS and AMESim software. Simulation results show that all kinds of valve power losses generate the greatest amount of heat, which accounts for about 40% of the total heat generation. The temperature difference of hydraulic oil before and after the radiator is about 10 °C, but the radiator cooling efficiency is low. The thermal equilibrium temperature increases with the ambient temperature. The hydraulic temperature control is adopted to drive the fan instead of mechanical driving, and the temperature control throttle valve is in parallel with the radiator in order to increase the cooling efficiency. The thermal equilibrium temperature of the improved system meets the working requirements. The results of this research can provide guidance for structural optimization and establishing control strategy of the loader vehicle thermal management system.

Structure design and working principle analysis of dual-entrance piezoelectric pump were carried out, and the relationship between output flow rate and the entrance area was inferred theoretically. The testing system was built and the output performances of single-entrance piezoelectric pump and dual-entrance piezoelectric pump were tested respectively. Testing results show that the maximum flow rate against zero back pressure of the dual-entrance piezoelectric pump is increased by 77.4 mL/min compared with single-entrance piezoelectric pump. The highest output pressure against zero flow rate of the dual-entrance piezoelectric pump is increased by 1.92 kPa compared with single-entrance piezoelectric pump. It is realizable for dual-entrance piezoelectric pump to achieve two kinds of micro fluid mixing. It turns out that the dual-entrance piezoelectric pump could enhance the output performance of single chamber piezoelectric pump, realize the mixing of two kinds of micro fluid, and variable mixing of two kinds of micro fluid by controlling the driving frequency of the pump.

The key processes of silicon microball bearing were investigated. First, the structure of raceway, the number of rolling elements and the nozzle of the bearing chamber of the microball bearing were designed. Then, the Halo Etch technology was employed to fabricate the blade with various characteristic dimensions and to improve the uniformity of etch rate and the pattern precision, thus, reducing the imbalance of rotor and increasing the stability of the microball bearing at high speed. Moreover, the intermediate-layer bonds and shadow mask technologies were used to encapsulate the bearing chamber and reduce the thermal deformation caused by the extremely high temperature and to avoid the clogging of the bearing chamber and the ball raceway adhesion caused by the deposited intermediate materials. A strategy for the design and fabrication of microball bearings in Micro-electromechanical System (MEMS) is provided.

In order to comprehensively analyze the influence of the grinding process system error on the manufacturing precision of rotor profile, a new method of error analysis of rotor profile is presented. This method consists of five independent error models and one synthetic error model. The machined rotor profiles are calculated by the error models, and the effects of center distance error, offset error, axial position error, setting angle error and pitch error on rotor profile are then revealed. Finally, the error of rotor profile is compensated based on the above error analysis and the tolerance is controlled within 0.01 mm. The results show that the proposed method can be well used to improve the manufacturing precision of rotor profile.

To improve the dynamic seal performance of reciprocating movement, the rubber plunger with groove shape surface is designed. The dynamic sealing characteristics of the rubber plunger are analyzed and optimization experiments of the structural parameters are carried out. The results show that the groove structure can significantly increase the interfacial contact pressure, improve the interfacial lubrication condition and reduce the friction resistance. The groove structural parameters obviously influence the dynamic sealing performance of the rubber plunger. The greatest impact factor on the leakage is the groove width, the medium impact factor is the number of grooves, and the minimum impact factor is the rove spacing. To reduce the plunger leakage, the groove width and groove spacing should be designed not too big or too small. The relationship between the number of grooves and the leakage is linear, the leakage decreases as the number of grooves increases. Analysis and experiment results show that the groove structure can improve the dynamic sealing performance of the rubber plunger.

In order to resolve the problem of multilayer goaf drilling and measurement, a new method, which adopts reverse circulation drilling technology with hollow-through DTH air hammer to pass through multilayer goaf is proposed, and a GQ-142 hollow-through air hammer is developed. The main performance parameters of the GQ-142 hollow-through DTH air hammer are computed using the program of “hollow-through DTH air hammer computational simulation and analysis” which is written in VB language. Analysis results show that the rated air pressure is 18×105 Pa, the rated air consumption is 14.86 m3/min, and the single impact energy is 413.07 J. A field test using GQ-142 hollow-through DTH air hammer to pass through multilayer goaf is carried out. Testing results show that, using DTH air hammer, the impact effect of rock fragmentation is obvious and the average drilling efficiency is 13.08 m/h. Using the GQ-142 hollow-through DTH air hammer and C-ALS 3D laser scanner can successfully pass through and measure the two layers of goaf.

An adjustable pressure apparatus for hot stamping quenching was developed, and ultrahigh strength steel 22MnB5 applied for automobile is tested in the apparatus. The two-stage color tint etching procedure for microstructure analysis and material property experiments were used for the optimization of the hot stamping quenching parameters. Results show that the critical pressure for 2 mm 22MnB5 in quenching is 0.3 MPa when the coolant is water in room temperature. Besides, the optimum pressure range in actual production for 2 mm 22MnB5 in quenching is over 1.0 MPa, and the best holding time is 8 s when the blank is cooled from 800 ℃.

Isothermal forging processing was applied to improve the coarse grain defects of traditional aluminum alloy forging in the forming of aluminum alloy lower arm. The forging process was simulated using FEM software Deform-3D. The grain size distribution and its changes during the forging process were analyzed. The coarse grain defects is isothermal forging and non-isothermal forging were compared. The forming reasons of coarse grain defects in different parts were discussed. Simulation results show that the isothermal forging processing can obviously improve the coarse grain defects of aluminum lower arm and help to obtain refined and homogenous grain group in forgings.

The Set Partitioning in Hierarchical Trees (SPIHT) algorithm requires a large number of tests to determine its significance during several times of scanning in sequence, which severely damages the efficiency of compression. To raise the SPIHT's compression efficiency, an improved algorithm of SPIHT used by Max-Heap Tree is proposed. It optimize the test function of significance and reduce the algorithm's time complexity from O(logn) to O(1). Experimental results show that the improved SPIHT is particularly efficient in continuous wavelet transforms, and its encoding time goes to be a constant and compression efficiency is improved by several times.

Channel interference factor for the identification results is prevalent among the existing speaker recognition algorithm. In order to improve the accuracy of the system, in this paper, feature warping is used to compensate the channel factor of Mel-Frequency Cepstral Coefficient (MFCC) features. Then, factor analysis technique is applied to deal with the channel factors of the speaker's Gaussian Mixture Model (GMM). In the endpoint detection phase of speech of this recognition system, the GMM for speech modeling is built to accurately determine the beginning and end points of the speech segment, and then the features after feature warping are used to establish speaker GMM. Using factor analysis technique to fit the differences between the speaker characteristics space and the channel space, the algorithm removes channel factor from GMM, and then extracts GMM super-vectors as input of the Support Vector Machine (SVM) to obtain recognition results. Experimental results show that the combination of channel compensation technique and SVM can obtain better recognition rate, and ensure the robustness of the system.

First, the cluster radius is adjusted periodically based on the node residual energy and the network is divided into several unequal clusters. Then, the cluster head election strategy is designed, which ensures the distribution of the cluster head more reasonable, improves the energy utilization of the cluster head, and balances the energy consumption of the nodes. Simulation results show that, compared to the Unequal Clustering Routing Algorithm (UCRA) and Cross Unequal Clustering Routing Algorithm (CUCRA), the CSAAS extends the network lifetime up to 55.2% and 38.2%, and meanwhile the transmission delay is lower.

A novel naive Bayes classification algorithm based on semi-supervised learning is proposed. First, to retain high quality samples in the training sect with class label, the unlabeled training set is sued to obtain k samples of high confidence. Then, these high confidence samples are combined with the labeled-training samples to iterate until the training is complete. The experimental results show that with the increasing proportion of unlabeled samples, the predictive accuracy of the proposed algorithm is significant higher than that of the Na?ve Bayesian classification. In addition, the effectiveness and performance of the algorithm are improved compared with the traditional semi-supervised learning algorithm.

Research of the cognitive recognition of twist-lock automation handling system is conducted. In this research, Kinect is employed to collect environment and objects information, and an improved incremental Principal Component Analysis (PCA) is proposed to build real-time cognitive recognition system. In online learning phase, the new class is monitored and feature vectors are updated incrementally based on the difference between the new input and the reconstruction one using current eigenvectors; the feature vectors are optimized and the inner-class distance threshold is updated adaptively based on comparison of inner-class distance. Thereby, the proposed algorithm can convert high-dimension information to low-dimension machine expression, learn, update and accumulate feature knowledge online, and complete pattern recognition task at the same time. Experiment results show that the proposed algorithm can improve the adaptability, robustness, recognition rate and real-time performance of a visual system, Moreover, calculation and storage space can be reduced by controlling the feature space dimension.

In order to solve the problem of parameter identification of ship's maneuvering motion, a fast convergent iterative least square algorithm is presented, in which the nonlinear and non-stationary characteristics of the ship motion in time domain are taken into consideration. First, the first-order and second-order nonlinear response motion of the ship are estimated and discretized. Then, the parameters are identified using the proposed least square algorithm, which is improved by using iterative learning and introducing p-type learning rate. The convergence of the algorithm is also analyzed. Simulation experiments are conducted and results show that the speed and precision of parameter identification are improved using this algorithm. This demonstrates that the proposed algorithm is feasible and effective.

A novel dataspace index method for efficient processing of path query is proposed. First, an example of joining the extended inverted index was illustrated to find the reason of inefficiency. Then, based on the extended inverted index, a B-tree index was built to efficiently search massive data. Furthermore, a secondary index was constructed in order to significantly reduce the number of repetitive comparisons with respect to index join process. Finally, a path query algorithm was presented based on the proposed dataspace index method. Experimental results show that the proposed method can not only efficiently deal with the problem of index join, but also significantly improve the performance of the path query in the dataspace.

Using the magnitude-square spectrum model and the exponential probability densities of the magnitude-square spectrum of the clean speech and noise. The new method updates the noise power spectrum estimation using the posteriori speech presence probability by incorporating a posteriori signal to noise ratio uncertainty. It can suppress effectively the background noise without introducing speech distortion. The simulation results reveal that the new method is characterized by tracking noise power spectrum accurately and following quickly abrupt changes in the noise spectrum. The quality of enhanced speech signal is improved in a certain extent.following quickly abrupt changes in the noise spectrum. The quality of the enhanced speech signal is improved in a certain extent.

A standard normalized correlation-based MUSIC method is developed for harmonic signal frequency estimation in α noise. First, as there is no finite variance in the α noise, the domain of the standard normalized correlation function is extended, and the α noise is suppressed by this function. Based on these, the MUSIC method for harmonic signal frequency estimation is proposed using the orthogonality between the harmonic signal frequency and the noise subspace. Compared with the fractional lower order classification method, the standard normalized correlation function is a linear operator, which greatly simplifies the calculation and analysis of the α stable distributed signal processing.

A robust image inpainting algorithm based on isophote is proposed. In this algorithm, first, the whole image information is obtained using Guided filter to remove texture detail and image noise. Then, the traditional isophote function is improved with the edge stopping function in anisotropic diffusion approach and is combined with the traditional priority function. Finally, using the isophote function to guide inpainting process of the texture, the proposed algorithm obtains robust inpainting effect. Experimental results show that the proposed algorithm can preserve image structure effectively, and obtain relatively ideal inpainting effect in the aspect of texture synthesis with illustration changes.

To overcome the problem of inter-path interference in existing multipath routing algorithms, a new algorithm, named Z-LBMR, based on load balancing is proposed, which can establish non-interference paths by shielding the interference nodes. Besides, to balance energy consumption of the network, the Z-LBMR algorithm allocates traffic load reasonably according to the current performance value of each path, thus, prolonging the network lifetime. Simulation results demonstrate that the Z-LBMR algorithm performs obviously better than existing multipath routing algorithms in packet delivery ratio, average end to end delay and network lifetime.

Based on the small signal suppression performance of hard-limiter, the interference signal is obtained. The reference signal of adaptive algorithm is formed using output signals of the hard-limiter; then based on the adaptive performance of Least Mean Square (LMS), the strong time-varying interference of GPS receiver input signal is cancelled. Finally, the interference signal is suppressed and the effective signal is obtained. Simulation results show that the proposed algorithm has good suppression performance for unknown strong interference signal and improve interference suppression capability by more than 30 dB when Signal to Interference Ratio (SIR) is in the range from -25 dB to -35 dB.

Traditional fair scheduling algorithms cannot accurately compute the achievable rate for each user in the process of iterative user selection, which results in non-favorable tradeoff between fairness and system sum rate. To address this problem, a fair scheduling algorithm based on weighted user-correlation (WUCFS) is proposed for MU-MIMO downlink broadcast channels. In this algorithm, users are activated based on comprehensive consideration of the correlation between candidate users and selected users as well as those to be scheduled potentially. Weighted correlation maximization is employed as scheduling criterion. The proposed algorithm could estimate the actual transmission rate of each user more precisely, and activate a set of users of small mutual interference with more fairness and appropriateness. Compared with existing schemes, the propose algorithm could achieve better fairness among users while ensuring high system sum rate.

This paper considers the secure transmission for MIMO wireless relay network. Each node is equipped with multiple antennas, and can acquire the global channel state information. The scheme combines the interference alignment and collaboration interference. Using precoding scheme the interference signal sent by jammer is aligned with the artificial noise sent by transmitter at the receiver, and it is independent of confidential signal subspace; then the receiver can eliminate the interference signal and artificial noise. The eavesdropper can also receive the transmitted signal, but it can not eliminate the interference signal and artificial noise as they are in the same subspace with the confidential signal. So its eavesdropping capacity is greatly suppressed. The signal transmission and precoding schemes for the transmitter, relay and jammer are designed, and the interference cancellation scheme for receiver is given. The secrecy performance is analyzed from secrecy rate and secrecy outage probability. Simulation results show that the proposed scheme can improve the secrecy rate and decrease the outrage probability compared with other systems.

First, in order to reconstruct three-phase power quality disturbance signals, the Fourier basis is chosen as the over-complete dictionary; Gaussian random matrices as the observation matrix; and orthogonal pursuit algorithm as the reconstruction algorithm. Then, the energy eigenvalue of gray level cooccurrence matrix texture features and the probability of the occurrence of grey value are used to classify the disturbance signals. The experiment results show that the proposed method can not only realize simultaneous compression and reconstruction of three-phase electric signals and accurate classification of such signals, but also reconstruct the original signal samples, reducing the data volume of signal compression and sampling.

With the continuous development of mobile terminals and business, in enterprise WLAN, user demand for throughput is gradually increasing. The traditional way of AP deployment and channel competition protocol can not satisfy the increasing communication demand. Therefore, many new methods have been put forward, such as interference alignment and combined beam forming. However, the use of these methods has certain limits and it is difficult to achieve good effect in actual use. This paper proposes a blind beam forming and nulling algorithm. This algorithm allows multiple terminals to transmit at the same time slot, on the premise of effectively improving the channel utilization rate, and better solving the problem of the interference of communication. Experimental results show that, compared with the traditional way of channel competition protocol and AP deployment, the proposed algorithm can effectively reduce the cost and improve the throughput of the terminal.

High performance acoustic underwater communication requires high data rate and high reliability. A new underwater acoustic communication scheme is proposed. In this technique, the nonlinear effect and self-adaptation characteristic of the acoustic parametric array and Orthogonal Frequency Division Multiplexing (OFDM) coding are combined together. An image file is transmitted in shallow water with depth of 20 m, and the OFDM in Quadrature Phase Shift Keying (QPSK) is applied. When the bandwidths are 6 kHz and 9 Hz, the system can achieve data rates of 3.224 kbit/s and 4.835 kbit/s, respectively, with Bit Error Rates (BERs) of 0.0068 and 0.0059. The sea trial results show that the proposed scheme is effective and feasible.

Least Square Weighted Smoothing Filter (LSW-SF) method is used to filter Magnetic Resonance Sound (MRS) signals, which is compared with the moving average filter method. Results of a large number of simulation experiments show the following characteristics. First, the more accurate characteristic parameters of MRS can be obtained using the LSW-SF method, and the Signal to Noise Ratio (SNR) is also improved. Second, the LSW-SF method is more suitable for random noise and rush noise removal. Third, appropriate weights should be chosen when the LSW-SF method is used to wipe out noise. Among them fitting error of MRS signal characteristic parameters can be controlled within 1%, and the smoothness of the signal curve is greatly improved. Meanwhile, the filter processing of the measured data indicates this method is effective.

The detection accuracy of the step wave reference orthogonal lock-in amplification is modeled and analyzed, and the implementation strategy based the principle of using simple hardware is presented. Considering the relationship between the frequency waveform distortion and the sampling rate, the synthesis strategies of step wave based on equivalent area method and selected harmonic elimination method are comparatively analyzed. According to the phase accuracy requirement of step wave reference signal acquisition and the periodicity of the signal to be tested, a matching sampling technique is proposed. Experiments results show that the proposed orthogonal lock-in amplification can achieved by Field Programmable Gate Array (FPGA), and the method is simple and has low hardware requirement, can be used to identify different anomaly bodies. The error of the improved method is 0.7% to 7.0%. Compared with the square wave reference orthogonal lock-in amplification, the detection accuracy is improved by the new method.

A lightweight paddy field weeder consisting driving-weeding compound components was designed based on the paddy production condition in China. The weeder is powered by a gasoline engine and the weeding rolls are driven to operate by a power transmission assembly composed of reduction gear and switch bevel gear system. A rotary harrow weeding roll with lower soil penetrating impact and better capacity to prevent sinking is designed using finite element method with fluid-structure interaction simulation. Depth of paddy mud (A), thickness of water layer (B) and rotary velocity (C) of the weeding roll are selected as the factors in the full scale field test to explore their effects on the average torsion of the principal axis, on the weeding rate and the injury rate of paddy seedlings. Variance analysis of the resting results show that the sequence of the factors affecting the average torsion and weeding rate are both B>A>C. the effect of the factors on the injury rate is insignificant. Lower average torsion and higher weeding rate can be achieved with larger depth of paddy mud. The average torsion decreases and the weeding rate increases as the water layer thickness increases. As the rotary velocity increases, the average torsion increases first and then decreases and the weeding rate increases. The optimum performance of the weeder can be obtained when the depth of paddy mud is 300 mm, the water layer is 60 mm and the weeding roll velocity is 160 r/min. Under such condition, the average torsion is 20.84 N?m, the weeding rate is 93.2% and the seedling injury rate is 1.2.

The effects of the penetrant Triton X-100 on the secretion of ginsenosides in Panax ginseng hairy roots were studied. Results show that Triton X-100 can effectively promote the secretion of ginsenosides and enhance the biosynthesis of ginsenosides in the hairy root. Moreover, under the presence of Triton X-100, the expression of dammarenediol synthase gene, the key gene in ginsenoside biosynthesis, is also elevated.