According to the configuration of a certain parallel-serial hybrid electric vehicle(PSHEV), a mathematical model was built for the vehicle control. An optimization function was proposed taking the engine fuel consumption minimization and the state-of-charge(SOC) idealization in the whole operation cycle as the targets. A dynamically limited SOC region model was built. A global search algorithm was designed for the dynamic programming. The shifting logic was also optimized. The PSHEV control strategy based on the power-tracking algorithm, that based on the dynamic programming and that based on the improved power-tracking algorithm were compared each other and the results show that the dynamic programming algorithm can be regarded as the reference of judgement for other control strategies, and can be used as to improve the control effectiveness of power-tracking control strategies.

A steering control strategy was proposed for the hydrostatic driving high-speed tracked vehicle on the icy-snowy road on the basis of the theoretical analysis of the steering driving of this kind of vehicle in comprehensive consideration of the safety criteria such as the affordable maximum pressure 48 MPa, driving without side and forward slip with enough adhesive force, etc. The steering control on the icy-snowy road was simulated using the software Matlab/Simulink, and the results show the feasibility and effectiveness of the proposed control strategy.

Aiming at the fact that there was no method to guarantee the consistency of the vehicle suspension kinematics by control on the tolerances of suspension structure parameters, a model was built for the uncertain structure parameters to establish the consistency of the suspension kinematics by the interval control method. Taking the parameter tolerances of the suspension structure as the uncertain parameters on the interval parameters, the consistency of the exteral characteristic was controlled by the proposed method. As an example, the consistency of a wishbone independent front suspension was controlled using this method, proving the effectiveness of the proposed method.

Tire cornering tests were conducted on a flat plate type tire test bed under different inflation pressures and vertical loads, parameters of the UniTire model(cornering force and aligning moment)were identified, and the correlation between these UniTire parameters and the tire inflation pressure was analyzed and characterized. A test method to predict the effect of the tire inflation pressure was proposed and a tire inflation pressure effect prediction model was built. The model parameters were calculated and the prediction of the cornering properties of the tire under another inflation pressure was realized. The accuracy of predicted cornering force and aligning moment exceeds 85%, demonstrating the validity of the proposed method.

Based on the deformation characteristics of the bus superstructure in the lateral rollover accident, three kinds of representative waist beam joints were extracted after investigating the joint types for the existing enclosed skeletons and their finite element models were developed accordingly to study the deformation characteristics during the rollover. Then three different joints were implanted separately in the enclosed skeleton and a comparison among the rollover performances was made. A preliminary conclusion about the influence of the rollover characteristics was drawn to provide a reference for the rollover safety design of the bus structure.

The theory of identification and validation in the modal test was discussed. The hammering modal test was done for the gearbox housing in a certain tracked vehicle. The model parameters of every order characterizing the dynamic behavior of the housing were identified using PolyMAX method. The identified modal parameters were analyzed and validated using the frequency response function synthesis and the modal assurance criterion before the correction of the structure model and the following dynamic behavior study. The results indicate that the identified modal parameters are accurate.

The effects of the valve timing on the gasoline controlled autoignition(CAI) combustion was investigated on a single-cylinder test engine system equipped with an electronic controlled hydraulic variable valve train system using the strategy of exhaust gas recirculation(EGR) in the exhaust port. The test results showed that at engine speed 1000 r/min, equivalent air-fuel ratio λ=1 and constant intake valve opening timing(IVO) 40 ℃A ATDC, the engine can work in CAI combustion mode with the exhaust valve closing timing(EVC) at 126~176 ℃A ATDC. When EVC=146 ℃A ATDC, the engine can work in CAI combustion mode with IVO at 28~60 ℃A ATDC. The impact of EVC on the exhaust gas quantity recirculated from the exhaust port was greater than that of IVO. In the operation region that the CAI combustion was realizable, the change range of IVO was only 45 ℃A, while the range of EVC might be up to 120 ℃A.

A short-term traffic flow prediction model was built based on KSOM-BP neural network. Using the kernel sample self-organizing map(KSOM) neural network, under the condition without a priori knowledge, the history samples with similar statistic character were classified into several categories by self-organizing and self-learning to enhance the statistic significance of the classified sample. A back-propagation(BP) neural network prediction model was built for the momentum-adaptive learning rate of every category sample to enhance the short-term traffic flow prediction accuracy, reduce the prediction time consumption. The model was validated using the practical road network data. The results show that the statistic index MARE of prediction error of KSOM-BP neural network is less than 7%, and less by 4% than that of BP network based on the whole sample without classification. The modeling time consumption of KSOM-BP neural network is also less than BP neural network without sample classification. All of this proves the validation and state-of-the-art of the proposed method.

Taking the rail transit terminal as the research object, the effects of the reliability of the serial units and the parallel units in the system on the reliability of the global system were analyzed through the establishment of the serial and parallel systems in the transfer facility. The reliability of the facility was defined as the probability that the passenger delay time is 0, and a reliability function model was built for the facility. The effects of parameters on the reliability were analyzed based on the reliability function versus parameters curves. The results indicate that the more serial units are in the system, the lower the system reliability is, and the parallel units are on the contrary. The reliability of the connection facility is affected by the width of facility and the passenger arrival rate, and the reliability of the service facility is affected by the average service rate of facility and the passenger arrival rate.

The consumer surplus and producer surplus of coordination system between rail transit and bus transit were analyzed according to the theory of welfare economics. Taking the maximization of social welfare as the target, non-coordinated schedule model and schedule coordination model were established. The solution approach to the model was proposed. The operation effect of transfer network before and after the implementation of schedule coordination between rail transit and bus transit was analyzed comparatively with a calculation case example. The results show that the implementation of schedule coordination increases the social welfare and benefit of passengers and operation enterprises.

The quantification process of the roadside landscape can be divided into 2 stages. The first stage is the image segmentation. Three segmentation methods such as marker-based watershed algorithm, Canny operator edge detection algorithm and texture analysis algorithm were comparatively analyzed, and the texture analysis algorithm which is characterized by more robust was selected. The second stage is the feature extraction of color space and continuity. In the extraction of the landscape color space, using the k-mean cluster analysis to extract the RGB vector of landscape, the color segmentation system was established making reference to the Munsell's color segmentation method, and the macro-color of the landscape was identified with high accuracy. In the extraction of landscape continuity, taking the landscape of section of Kunyuan freeway as a case example, the HSV values based on time series were extracted. The relationship between the HSV color space and the roadside landscape was analyzed quantitatively and the results show strong correlativity.

A two-step method was proposed to identify the damage of the simply supported beam bridge with multiple girders. The method identifies the structure damage using the modal curvature difference and the neural network technique to avoid the disadvantages of each single method. A numerical example was provided for a simply supported T beam bridge with five girders to verify the feasibility of the method, and the results show that this two-step method is effective to locate damage and evaluate the damage degree.

A finite element analysis model was built for the asphalt mixture including the aggregate, the air void, and the asphalt mastic using the specimen images acquired by industrial CT and the digital image processing(DIP) as well as the finite element modeling(FEM) technique. The splitting tests(indirect tensile tests) of the asphalt mixture were simulated in consideration of the air void distribution, different loading directions, and different aggregate asphalt modulus ratios. The results indicate that the stress concentration factor can be used to describe the distribution of stress inside the asphalt mixture, and the mixture gradation, the modulus ratio, the air void and the loading position affect the simulation results significantly. By the DIP-FEM method the microstructure and the macromechanics of the asphalt mixture can be interrelated well.

The tungsten inert gas arc welding(TIG) technology was applied on aluminum alloy 5554. The microstructure and mechanical properties of welded joints by different solders were compared using the universal tensile testing machine, the optical microscopy and the micro-hardness tester. Results show that with the increasing content of magnesium in the solder, mechanical properties of welded joints became weaker, and more heat cracks appeared in the solder. The micro-hardness in welded joints with three kinds of solder is all lower than the parent metal.According to the experimental verification this is resulted from the thermal insulation after welding.

Mathematical expressions were given for the part with 3-dimensional curved surface formed by continuous forming process based on the sweep surface method. A circular arc interpolation algorithm to deseribe the geometric shape in longitudinal direction of the formed part and the method to control the longitudinal forming process were presented through the analyses of the deformations in longitudinal and transverse directions of the sheel metal during the continuous forming process. A B-spline interpolation method to describe the shape of the flexible roll axis was proposed, and the method to control the shape of section curve of the formed surface was given. The validity of the presented methods was demonstrated by the continuous forming tests of the typical parts with curved surfaces.

The tensile test was done for the axial tensile specimen with single edge crack notch processed by laser. The specimen was sampled from the connecting rod blank forged by the high-carbon micro-alloyed non-hardening-and-tempering steel(S70S6). The influence of the laser processed single edge notch on the tensile fracture of specimen was analyzed, and the fractography and the fracture load of the specimen with the laser notch were compared with the specimens with the notches processed by wire cut electrical discharge(WEDM) and broaching. The results show that the specimen with laser notch was characterized by the smallest notch tip plastic deformation region, it can be fractured by the smallest axial tensile load which is about 20% and 30% smaller than that of the specimen with WEDM notch and broaching notch, respectively. The equivalent critical stress intensity factor was defined based on the test results which is 25.51 MPa·m^1/2.The results provide a reference for the load parameter calculation of the fracture splitting connecting rod with starting notch processed by laser.

A calculation method for the braking torque of the hydrodynamic retarder under partial filling condition was proposed based on the one-dimensional flow beam theory to estimate the retarder braking performance in the product design phase. The proposed method as well as the general CFD numerical simulation were applied to calculate the braking performance of D300 type hydrodynamic retarder under partial filling condition and the results were compared each other. The both results show a good agreement, proving the effectiveness of the proposed method.

The dynamic operation behavior of the computer numerical control(CNC) machine tool was analyzed and a stochastic Petri net model was built for its reliability. The corresponding status at every failure time of every subsystem was obtained by the total failure time method. A dynamic availability model was established for the CNC system and its subsystems by the Monte-Carlo simulation of the Petri net. Taking 261 fault data of 7 CNC machine tools as examples of analysis, the histories of the availability of the CNC machine tool and its subsystem were obtained, providing a basis for establishing a reasonable maintenance policy and predicting the availability status for the CNC machine tool.

The composition of the electronic control system of the satellite attitude control flywheel(SACF) and the cause of its electromagnetic interference(EMI) on other satellite-carrying equipments were discussed in detail, and a method to reduce or surpress the EMI in the electromagnetic compatibility(EMC) design of the SACF electronic control system was proposed. The effect of suppressing the EMI through EMC design was investigated by EMC tests. The results show that in the proposed EMC design the CE102 conducted interference test met the standard requirement, and different frequency bands were characterized by different margin, the largest was up to 26 dBμV. The RE102 radiation interference vertical polarization test had 7 dBμV/m margin at least, and the horizontal polarization had a greater margin. The design also passed five sensitivity tests of satellite-carrying equipment successfully.

As a typical uncertain system with several independent perturbation blocks, the hydraulic control loading system(HCLS) is characterized by unsatisfactory column-hold stability and smoothness with the application of the classic PID controller. To overcome this shortcoming, a robust controller was developed based on μ-synthesis. Compared to the classic PID controller experimentally, the robust controller could improve the column-hold stability and smoothness of the HCLS.

Current five-axis linear interpolation method for sculptured surface machining has the drawbacks of low-speed, low-accuracy and large Numerical Control (NC) file. To overcome these drawbacks, a five-axis CNC controller with fairing function for spline curve interpolation was proposed. The construction method of spline curve in this CNC controller and the real-time spline curve interpolation method were introduced. For machining of workpieces with streamline form, before real-time interpolation, fairness judgment of the sequence of cutting tool centre points, provided by CNC file, was carried out. Those tool centre points that did not satisfy the fairness judgment were modified. Machining case demonstrated that the proposed method can avoid all the drawbacks of five-axis linear interpolation method. Application showed that the new CNC controller can achieve good machining results for workpieces with streamline form.

To enhance the accuracy and efficiency in the product design of the automotive ignition coil, a simulation algorithm was proposed based on the electromagnetic analysis to calculate the secondary voltage of the coil. According to the working principle of the ignition system, the functions of the ignition module and the ignition coil were simulated to establish the electrical calculation model for the secondary voltage. The magnetic structure of the ignition coil was analyzed, using the coil turn the wire diameter and the iron core length as input parameters, a calculation model was built for the technological and structural parameters to reduce the calculation error caused by the impact of the nonlinearity of parameters and magnetic factors. The simulated results are in good agreement with the experimental ones, showing the validity and practicability of the modeling algorithm.

A new 4-UPS-UPU five-degree of freedom Parallel Coordinate Measuring Machine (PCMM) is proposed. The stationary platform of PCMM is connected with the moving platform by four identical Universal-joints Prismatic-pairs Spherical-joints (UPS) driving links and one Universal-joints Prismatic-pairs Universal-joints (UPU) link. Integrating CAD, CAE and visual technologies, the dynamic behaviors of the rigid-flexible PCMM was investigated. The three-dimension model of PCMM was built in SolidWorks. The modal neutral file of the flexible body of driving limbs was generated in ANSYS. Then the rigid-flexible virtual prototyping of 4-UPS-UPU PCMM was built in ADAMS. Based on the rigid-flexible model, the dynamic behaviors, including kinematics output response, dynamic stress of driving limbs and natural frequency were simulated. Simulation results show that the flexibility of the driving limbs significantly impacts the system dynamics, the proposed rigid-flexible model can reflect the dynamic behaviors of PCMM.

Most of the component optimization designs of the commercial vehicle are limited to the individual component because of the complex coupling relations between components. Focusing on the optimization problem of the vehicle component under full vehicle environment, a concept of modal stiffness was introduced, a modal stiffness sensitivity(MSS) was defined based on the finite element or the superelement, and the MSS calculation method was derived. The proposed method was applied to MSS analysis of the cab of a commercial vehicle under full vehicle environment. In the calculation, a 3-D finite element model was built for the full vehicle and the cab was divided into 15 superelements. the obtained MSS can be directly used to improve the structural design of the cab. The proposed method provides a simple and effective approach for the optimization of vehicle components under full vehicle environment.

In view of the situation that the national standard“Code for Design of Concrete Structure”does not give the target reliability index of the concrete structure member in the serviceability limited state, a method of reliability analysis was proposed for the concrete structure member under the normal service state based on fuzzy invalidation criterion. A fuzzy membership function was built for the concrete. The structure fuzzy reliability problem was transformed to a traditional reliability calculation problem by the method of establishing an equivalent functional function. The fuzzy reliability index for the transverse crack in the concrete structure member under the normal service state was calculated by JC solution method.Compared with the traditional analysis method, the method considering the fuzziness gave less reliability of concrete structure, this provided one of the theoretical supports for concrete structure design.

To solve the difficult issue of crop precise fertilization, a neural network ensemble approach is proposed, which is based on the complex network clustering algorithm. In this approach, first, the method of sampling with replacement is adopted to produce the number of neural network units. Then, Yang's network clustering Forward Error Correction (FEC) algorithm is used to select the networks with high precision and great diversity. Third, the selected networks are ensembled separately with linear weighted ensemble method and nonlinear ensemble method. Finally, the prediction result is achieved by amalgamating the results produced by the two ensemble methods. Test results, carried out at the No. 7 corn plot in Yushu city in 2008, reveal that it proposed approach is better than the traditional fertilization models, linear weighted ensemble model and nonlinear ensemble model. In addition, the ability of generalization of the approach is strong.

A hierarchical qualitative spatial representation and reasoning approach was proposed by Sanjiang Li and Bernhard Nobel. In this article, under fixed resolution, we expand and complement this spatial representation and reasoning approach to determine the mereological (part/whole) relations between two rough regions. In particular, we discuss reasoning issue when the lower approximation is zero. We complete the theorem which determines the definite RCC5 relation between the two rough regions. The improved approach can also applied to other RCC relation theories.

Satisfiability (#SAT) is an important problem in artificial intelligence. May algorithms for solving #SAT problem are only appropriate for small clause number. The runtime increases rapidly with the enhancement of clause sets' scale. We propose a new algorithm, named MCEHST, using extension rule indirectly. There two steps in this method. The first step calculates all minimal hitting sets of a clause set. The second step counts models with these hitting sets using extension rule. Experiment results show that the proposed MCEHST is more efficient than CDP and CER under large clause number and short clause length. Using MCEHST the increase in runtime is slower than CDP and CER.

An improved AdaBoost algorithm, IL-AdaBoost, for XML document classification is proposed. IL-AdaBoost uses frequent change of substructure with XML as the feature to build the decision stumps, then uses the decision stumps as weak classifiers, and improves AdaBoost algorithm. IL-AdaBoost is used to simulate new generation of XML documents through Poisson process, which reflects the characteristics of increase in XML documents with time, and updates the distribution of the sample to achieve incremental learning. IL-AdaBoost reduces the differences of basic classifier by sampling, and improves ensemble learning.

An alive entropy model is proposed for detecting increasingly serious Denial of Service (DoS) attacks. The model is based on the theory of active communication that combines the information entropy and related sessions of network flow. The model detects DoS attacks through the analysis of the variation of the network flow's alive entropy. Experiment result show that the alive entropy is stable under normal network flow, and when attack occurs it fluctuates obviously. Compared with other methods based on the static entropy model, the proposed model is more accurate and more effective in detecting unknown DoS attack.

A method to define requirement dependency and then to determine crosscutting concerns from this requirement dependency is proposed. First, atomic requirement dependency is defined with respect to the system resources. Then, the concept of requirement cluster is provided and the way to group requirements into clusters is introduced. Finally, an approach to determine crosscutting concerns from requirement dependency and conflict analysis is presented. The feasibility and effectiveness of the proposed method are demonstrated by a case study to apply this method to an existing system.

Low classification accuracy is one of the major restrictions to the use of microarray data in clinical diagnosis. To solve this problem, by taking consideration of the characteristics of high-dimension and small sample of DNA microarray dataset, a novel classification approach was proposed, which is named feature subspace ensemble classification. In this approach, first, hierarchical clustering and signal-noise ratio feature selection strategy were used to project the training dataset from original space to a non-redundant feature gene space. Then, mass feature subspaces were extracted to construct training subsets, and support vector machine was used to train base classifiers. Finally, the majority voting strategy was applied to classify the testing samples. The effectiveness and feasibility of the proposed approach was verified on four benchmark microarray datasets. Experiment results show that better classification performance can be obtained by the proposed approach than majority of the current ensemble classification approaches on microarray data.

Non-negative Matrix Factorization (NMF) is brought forth into document cluster ensemble problem. In order to get a stable result, K-means algorithm using minimum and maximum principle is performed. Then the result of K-means is provided to NMF algorithm as the initial factor matrix. NMF is further performed on adjacent matrix of hypergraph to attain the basis matrix and efficient matrix. The final clustering result is obtained according to the coefficient matrix. Whereupon, a NMFK algorithm is proposed and tested on real-world document sets. Results show that NMFK outperforms other cluster ensemble techniques and is very efficient.

The current thresholding methods are mostly based on 2D or 3D histograms of grayscale, neighbor average grayscale and neighbor median grayscale. These methods include 2D minimum error method, 2D Renyi's entropy method, 3D Otsu method etc. The segmentation precisions and noise immunities of these methods are not satisfactory. A novel thresholding algorithm based on 3D Renyi's entropy is proposed, the dimension added is the weighted neighbor median grayscale. Compared with other existing methods, it can not only satisfactorily filter the noise, but also reserve the edge details to a certain extent. Experiment results on many images indicate that this algorithm is able to promote the precision and noise immunity effectively.

Based on the theory of model predictive control, a novel Active Queue Management (AQM) algorithm is proposed for typical Internet systems with large delay, called MPAQM. First, the predicted output is defined by considering the causality of time-delay system. Then, according to the predictive model and state estimator, the future dynamic queue length in data buffer is predicted. Finally, the control requirement of congestion is converted to optimal control objective function, and drop probability is obtained by solving the optimal problem. The performances of MPAQM are evaluated through a series of simulations in simulator NS2 with single and multiple-bottleneck network topologies. Simulation results show that the proposed MPAQM algorithm outperforms RED and PI algorithms in terms of stability, disturbance rejection and robustness.

To overcome the poor transparency of using wave variable algorithm in time-delay teleoperation system, a novel method was proposed for incorporating wave variable algorithm with prediction in a three-channel (3CH) architecture of teleoperation system. This method is capable to guarantee the stability of time-delay teleoperation meanwhile increase the transparency. A 3CH teleoperation control architecture was established for the system in the absence of force sensor in the master side, and a parameter selection method for 3CH architecture under the condition of ideal transparency was presented. To extend wave variable algorithm to a 3CH teleoperation architecture, the communication channel was divided into a two-port model by reasonable combination of force and speed information. Then the I/O signal of the two-port model was transformed into wave variable. A predictor was added in wave domain of the master side to further enhance the transparency of the system, and an energy regulator was designed to ensure the predictor being passive. The transparency and stability of the system were analyzed. Experiment results show that the proposed method can guarantee the transparency and stability of time-delay teleoperation system.

To solve the problems of particle degeneration in traditional particle filter, an improved target tracking algorithm was proposed based on density estimation with support vector machines. Using support vector machines, the posterior probability density function of the state was estimated with predicted particles and their important weights during filter iteration. After resampling the new particles from this density model, the degeneration of the filter was eliminated effectively by these diversiform particles. Simulation results demonstrate that the proposed algorithm can increase the quantity of effective particles obviously, and the new filter is superior to the Markov Chain Monte Carlo particle filter and regularized filter.

A new mine rescue robot is designed in order to enhance the rescue capacity of mine rescue robot. A visual tangent graph concept is discussed for modeling unknown environment. A path planning method in unknown environment is proposed for the new mine rescue robot based on the visual tangent graph. A local optimal path guided by the global goal is searched using the “least direction deviation” heuristic functions. The simulation results demonstrate that the path planning method is feasible with better environment adaptability, which satisfy the motion requirement of the new mine rescue robot in unknown environment.

Mathematical models were built for the flow and pressure control of the direct drive electro-hydraulic servo system to realize the optimal pressure and flow compound control of the system. A constant pressure and limited flow control method was proposed based on the parameter switch by the pressure difference, and on this basis the pressure and flow switch control method was corrected. This method enhances significantly the system response under the prerequisite of meeting the system stability. The experimental results show that, by means of reasonable integral and dead zone regulation, both methods can make the pressure and flow switch smoothly, the system sensitivity to the changes of actuators and load parameters was declined, and the system response was improved. These results confirme the validity of the proposed method.

An approach to identify the inertial parameters of an underactuated spherical robot is presented, which is based on an Inertial Measurement Unit (IMU). First, a dynamic model of the spherical robot was constructed using Kane's method. Then, using the three underactuated equations of the constructed dynamic model, the identification model of inertial parameters of the spherical robot was derived. Finally, the proposed method of inertial parameter identification was validated by experiment on a new type of spherical robot as the experimental platform, using the real information of the IMU fixed on the frame of the robot. Experiment results show that the proposed method is simple and feasible that the identified parameters are reasonable. The method can be applicable for the identification of inertial parameters of other underactuated robots.

A method of constructing grid map using improved Dempster-Shafer (D-S) evidence theory was proposed for unstructured environment mapping. A mobile robot was used to explore environment with ultrasonic sensors. The problems that the D-S evidence theory can not be applied to information fusion under certain circumstances and that it has counterintuitive behaviors in some cases were discussed. An approximate process algorithm was developed to avoid the above problems and improve the D-S evidence theory. This improved D-S evidence theory was used to fuse multi-sensor information; then a two-dimensional D-S grid map was built. With D-S evidence rule of decision making, a 0 1 grid map was built. The D-S grid map was analyzed, and an algorithm to evaluate the environment and environment exploration effect based on D-S grid map was proposed. Simulation results show that the improved D-S evidence theory is appropriate to unstructured environment mapping.

Based on the Lyapunov stability theory and active control method, a new non-linear control method was proposed, which ensures the effective and precise synchronization of two different chaos systems in finite time. The synchronization of two different structure chaos systems at precise time can be achieved by adjusting the parameters of the controller. This method can be used for common chaotic systems. Taking the Chen system and Liu system as the objects of study, theoretical analysis and numerical simulations confirms the effectiveness of the proposed method.

According to the principle of the production of voiced and unvoiced speech, we estimated their probability density functions of speech spectral amplitude more accurately, and derived the speech enhancement algorithm. Matlab simulation verified the superiority of this algorithm.

A high-order diversity scheme is proposed for relay cooperation by using network-channel coding approach. The information received by the relay node in different time is coded with a channel coding method. Then all the codes are forwarded after network coding. Using iterative and maximum a posteriori decoding method, the information can be obtained at the destination node by decoding the codes received in different time. The pairwise error probability analysis under Rayleigh fading channel shows that the proposed scheme can increase time diversity gain by forwarding the information several times at source node in different time slots. Simulation results show that the scheme can obtain higher diversity gain in both fast and slow fading channels. Furthermore, the performance can be improved as the received signal to noise ratio of the relay node increases.

A pilot spacing design method is proposed, which can maximize the average spectral efficiency. Based on the adaptive Orthogonal Frequency Division Multiplexing (OFDM) systems, the impact of channel estimation on Bit-error Rate (BER) is analyzed. On the constraint of an instantaneous BER, a formula for average spectral efficiency as a function of pilot spacing is derived based on which the optimal pilot spacing is designed. Simulation results show that the optimal pilot spacing is related to Signal-to-Noise Ratio (SNR) and coherence bandwidth, and the validity of the proposed method is verified under different channel models.

In this paper, an improved localization algorithm, called Enhance Localization with Mobile Anchor Points (ELMAP), is developed. This improved algorithm is based on Localization with Mobile Anchor Points (LMAP) algorithm. ELMAP improves the original beacon point selection for the sake of shaking off the dependence on the assumption of transmission range and enhancing the localization performance in practice. It selects the beacon messages, possessing the same value of Receive Signal Strength (RSS), as the beacon points to estimate the coordinates of unknown nodes. Simulation results show that the environment adaptability of ELMAP algorithm is much stronger than LMAP algorithm, and the performance could be optimized by adjusting the number of the beacon messages and restricting the RSS value of the beacon points.

An adaptive hybrid gateway discovery algorithm for connecting mobile ad hoc networks to internet was proposed. This algorithm overcomes the limitation that the internet connectivity performance is greatly degraded due to blindly rebroadcasting gateway discovery message when obvious unidirectional links are ignored. Based on the expansion of the AODV protocol, by rebroadcasting the gateway discovery messages and gateway advertisement messages, both of which are extended with local connectivity information, the unidirectional links are successfully removed from global route computations by the algorithm. Furthermore, an adaptive internet working scheme was adopted to provide the best coverage of gateway advertisement by dynamically adjusting broadcast range and sending interval of gateway advertisement messages according to the network conditions. Simulation results show that the proposed algorithm can effectively avoid unidirectional links with reasonable overhead and provide better connectivity performance than others.

An adaptive cooperative relay protocol is proposed, which can be adopted in future broadcast system. The outage probability performance of this protocol is analyzed using the moment generating function and inverse Laplace transform in the fading channel, and the asymptotic expressions for the outage probability are derived. This protocol is compared with the existing decode-and-forward protocol and the respective application scenarios are acquired. Combining numerical simulation and theoretical analysis, the working relay amount, the relay locations, the power allocation and their impact on the system performance are further analyzed. According to the results, the advantages and characteristics of this protocol are confirmed.

The face recognition method based on two dimensional discriminant algorithm lacks the use of nonlinear feature. To overcome this shortcoming, a two dimensional discriminant analysis algorithm based on kernel method is proposed for face recognition. Test results show that the proposed algorithm performs better than the original one. Further research on polynomial kernel functions shows that the lower degree polynomials receive higher recognition rate.

We proposed an improved image segmentation model based on Local Binary Fitting (LBF) to solve the difficulties in finger vein image segmentation caused by fuzzy localness, low contrast and inhomogeneous intensity. The model inherits the advantages of LBF model in selecting Gaussian kernel to acquire local information, which is very effective for segmenting image of inhomogeneous intensity. Specially, a weighted total variant component with edge stopping function is added to the improved model, which gives the model higher sensitiveness to edge information and better performance on segmenting image with low contrast. Level set regularization is introduced to the model to avoid re-initialization of the level set function, thus reducing the evolution time. Experiments on simulated data and real finger vein images indicate that the improved model is effective for finger vein image segmentation, which has higher segmentation capacity with regard to detailed edge information. Also it is less possible for the improved model to fall in local convergence.

Polarization filtering technique has been developed as an efficient way to suppress radio interference in recent years. To further suppress the interference using polarization filtering technique when the target and the interference polarization parameter are non-orthogonal, a novel polarization filtering method is proposed, which is called the Oblique Projection Polarization Filter (OPPF). First, the polarization parameter subspaces of the target signal and interference are estimated in time and frequency domains. Then, the oblique projection operators are constructed to form the polarization filtering vector. The proposed OPPF can effectively mitigate the radio interferences in time and frequency domains. The OPPF is the extension of conventional polarization filter. The effectiveness of the proposed OPPF is validated by theoretical analysis and simulation results.

For a large-scale biogas project in Heilongjiang province, based on finite element model of steady-state thermal balance, the total daily mean heat loss of a digester was analyzed under the condition of the lowest mean temperature. Results show that the daily mean temperature reduction of the fermentative materials is less than 1 °C. The proportion of heat loss in different part of the digester is also obtained. According to the results, the digester structure and insulating system for this large-scale biogas project was designed. The heating system was optimized by replacing the heat exchanger, which was located between the acidification digester and biogas digester, with general heating circular pipeline. Thus, the incrustation and rust leakage of the pipeline could be avoided and the energy consumption was reduced. The temperature of the heating material was adjusted according to daily mean temperature drop of the fermentative material in the digester to make the temperature of the mixed fermentative material be up to 35 °C. The key parameters of the heating material for external heating of digester were investigated. Our study can provide reference for the design and optimization of the heating system of large-scale biogas project in northeast China.

The ethanol fermentation from corn stover pretreated by wet oxidation was studied. The recovery of cellulose and hemicellulose, the enzymatic conversion of cellulose and ethanol yield after the pretreatment were investigated. The cellulose recovery of 94.6% was obtained after the corn stover was pretreated by wet oxidation under the conditions of 195 °C, 15 minutes, 12×105 Pa O₂. About 88.3% of the cellulose was remained in the solid cake and most hemicellulose and lignin were solubilized. After 24 h of hydrolysis of the solid cake using cellulose, the conversion of cellulose to glucose was about 65.8%. After 142 h of simultaneous saccharificiaton and fermentation with substrate concentration of 8%, about 75.2% of theoretical ethanol yield was obtained. The estimated total ethanol production is 165.7 kg per ton raw material if the cellulose is fully consumed.