Abstract:In order to reduce thermal errors and improve machine accuracy, a new kind of thermal error modeling method, which takes temperature and machining parameters as input parameters, was established on the basis of time-series regression analysis and numerical computation. The model consists of a thermal error model, a thermal properties model of hydrodynamic bearing and a thermal transfer model of the spindle. Firstly, the correlation model between the temperature data serial of thermal points and thermal error data serial was established on the basis of time series correlation analysis. Then, the number of thermal points was reduced by calculating the grey correlation. In the meantime, the thermal properties model was established based on time-series regression analysis and numerical computation method. A predicting model of thermal error was established for a large CNC gantry grinder. It is indicated by experiment that the thermal error model has good recognition function for thermal error.

Abstract:Based on the cooling mechanism of the turbocharger bearing, a fluid mesh model and a solid one for simulation were built by using the professional software CFD and FEM. Numerical simulation of the coupled heat transfer of the turbocharger bearing was carried out in the fluid-solid coupling method. And then, the data of flow field, heat transfer coefficient and temperature field for fluid region of bearing was obtained, and the temperature field for solid areas was analyzed. The simulation results show that the temperature distribution of the bearing is more uniform, resulting in better cooling performance under the cooling way by using both oil and water at the same time. The experiment shows that the temperature distribution of the simulation model accords with that of the actual turbocharger bearing, which proves the feasibility of this method.

Abstract:To improve the transient response of exhaust turbocharging engine under accelerated conditions, a method of steam-assisted turbocharging was proposed. Based on an exhaust turbocharged gasoline engine, the simulation models of steam-assisted turbocharging and exhaust turbocharging engine were established and then calibrated by the software of GT-Power. On this basis, the effect of various steam parameters on the performances of turbocharging system and the gasoline engine was studied at the engine speed of 2000 r/min. The results show that, at the accelerated condition of 2000 r/min, the retarded time of the gasoline engine can be reduced by 48.0% and the peak torque can be increased by 9.7% through steam-assisted turbocharging. As a result, the acceleration and dynamic performance of the gasoline engine can be effectively improved by steam-assisted turbocharging.

Abstract:In order to address the matching optimization of one bus with variable stiffness suspension, traditional suspension matching methods and processes were firstly summarized and then the virtual matching optimization method was proposed based on Computer Aided Optimization (CAO) technology. The corresponding matching process was also given, in which the virtual dynamic optimal model of the vehicle was established, the matching optimization was programmed and the optimization goal was also set. For an accurate virtual model, the mechanical characteristics of the bus' tires were tested and the inertial parameters of the bus' sprung mass were also measured under unloaded and full loaded states. The matched suspension parameters included the torsion stiffness of front torsion bar, the pre and post damping curve coefficients, the torsional stiffness of pre and post stabilizer bars, the two-stage variable stiffness of rear suspension and the radial stiffness of the leaf spring bushing. When virtually matching, the vehicle performance under two kinds of loaded states (unloaded and full loaded) was considered respectively. Then, the matched results of the variable stiffness suspension were obtained. The suspension samples were made according to the matched results, and the comparative trials of vehicle were done in an automotive proving ground to evaluate the optimization effect. The results show that the proposed virtual matching optimization method is effective and feasible for matching the variable stiffness suspension parameters.

Abstract:Based on a new regeneration model with microwave heating for rotary unit-block diesel particulate filter, the filter body wall temperature along the radial distribution and structure parameters of the filter unit on the influence of microwave heating during the regeneration process were obtained by numerical simulation. The results show that the wall temperature gradually increases from the outer surface to the inward surface and the peak temperature emerges in the inward surface; the smaller central angle will shorten the regeneration time; the smaller length and the smaller thickness can shorten the regeneration time. The results provide important theoretical guidance for the optimization of the regeneration process.

Abstract:For the accurate control of the air-fuel (A/F) ratio at transient condition, the traditional PID controller cannot achieve satisfactory results due to the inherent nonlinear characteristic and time delay of single cylinder engine. So, this paper constructed an improved fuzzy PID controller with dynamic time delay compensation. First, a model for single cylinder model was set up and a common fuzzy PID controller was applied to solve the non-linear problem. Then, a modified dynamic compensator was proposed to improve the time delay behavior inherited in single cylinder gasoline engine. And then, the compensator was coupled to the fuzzy PID controller and applied to the A/F ratio control of the engine under transient condition. The simulation results show that the improved fuzzy PID controller can not only compensate the non-minimum phase characteristic of the engine system caused by the time delay, but also adapt well to the nonlinear characteristics, and in return, the stability, accuracy and response speed of the control system are greatly improved.

Abstract:In order to study the influence of different rock temperatures on the rock breaking characteristics of TBM disc cutter tunneling parameters, and on the basis of particle flow theory, the thermodynamic mathematical model of rock breaking by TBM disc cutter based on rock temperature changes was established from the microscopic view. The whole process of rock crack formation, crack propagation and rock slag formation was simulated. Then, the influence laws of different tunneling parameters on rock breaking characteristics were studied, which explained the rock breaking mechanism of TBM disc cutter under different rock temperatures from micro view. Finally, by using the linear experiment platform of rock breaking by TBM disc cutter, experimental verification was accomplished to find out whether the influence laws of rock breaking characteristics by TBM disc cutter tunneling parameters under different rock temperatures conditions were kept well with numerical simulation results. The research results show that: (1) the increase of rock temperature decreases some mechanical properties of rock such as hardness, strength and so on, which leads to the crack number increase and rapid expansion of micro crack when rock breaking rock, hence reducing the rock breaking load of TBM disc cutter and improving the rock breaking efficiency; (2) the higher the temperature, the lower the rock stress. The stress distribution obeys the Buzin Neske stress circle rules, where the stress value below the region of the cutting edge was the maximum and gradually decreases radiation around. The stress is basically symmetrical distribution and total rock stress becomes smaller as temperature increases; (3) when the penetration depth is low, the rock is not easy to be broken and intruded. With the increase of rock temperature, the rock is easier to be extruded and ruptured. With the increase of the penetration depth, the failure zone is further expanded, which improves the rock breaking efficiency; (4) the synergistic action between TBM disc cutters decreases with the increase of the cutter space, and the optimal cutter space increases with the increase of rock temperature and penetration depth; and (5) the synergistic action between TBM disc cutters can be enhanced by increasing rock temperature to improve the efficiency of rock breaking.

Abstract:A measurement and control system for lithium electrode material graphitizing was designed on the basis of the platform of MCGS configuration software, RS485 bus and net technology and with an IPC used as the system host. The measurement and control system contains two 485 nodes. An electrical parameters collector was used to collect Rectifier Transformer's electrical parameters, and a controller was used to control Transformer gears. A second-order low-pass filter was designed on the basis of linear photoelectric coupling. The output voltage and output current of Rectifier and other signals were managed by a signal processing circuit and collected with Intelligent Data Acquisition card. An algorithm of the automatic control transformer gear was presented, which can match the set power curve in real time and implement the optimal control of the graphitization process. System host access the intranet through optical fiber, realizing the function of remote monitoring. This system has been put into use for more than one year, and the operating effect of more than 120 furnaces shows that the system is stable and easy to operate, the quality of product is stable and power consumption declines by 6%.

Abstract:A new scheme of implementing Morlet complex wavelet transform using poles-shared Switched-current (SI) circuits was proposed， in which a hybrid method in time and frequency domain was presented for approximation of Morlet complex wavelet. By decomposing the Gaussian envelop, which is a component of the Morlet complex wavelet, an approximation optimization model in time domain was designed, which can be solved in universal optimization algorithms. By using the periodic characteristics of the sine and cosine signals, the Laplace transforms of the approximated Morlet complex wavelet can be simplified. The rational real and image parts of the approximated Morlet complex wavelet have shared poles because the product of sine and exponential and that of cosine and exponential have same poles in s-domain. A kind of SI complex second order section circuit was designed based on the bilinear z-transform integrator module. Then it was used to synthesize the Morlet complex wavelet base circuit. By adjusting the circuit’s switch clock frequency, the wavelet transform in other scales can be realized. The comparative analysis demonstrates that the proposed approximation method is better than the Padé transform and Maclaurin series method in accuracy and stability. Furthermore, the circuit designed has the advantages of more simple structure, lower power consumptions and smaller volumes, compared with the existing method. Simulation results verified the effectiveness of the proposed scheme.

Abstract:The quick and accurate estimation of the state of charge (SOC) of lithium-ion battery is one of the key technologies of battery management system. In view of this nonlinear dynamic system of lithium battery, through the test and analysis of lithium-ion battery hysteresis characteristics, the second-order RC hysteresis model was established, and the cubature kalman filter algorithm was used to estimate the battery state of charge. The experiment results show that the battery model can essentially predict the dynamic hysteresis voltage behavior of the lithium-ion battery and cubature kalman filtering algorithm can maintain high accuracy in the estimation process.

Abstract:Three optimization models of inter-regional generation scheduling including clean energy generation, taking minimum regional generation cost, and minimum regional carbon emission cost and minimum comprehensive cost as objective functions respectively, were established, and the models considered the issues of economic efficiency, carbon emission, and transmission constraints. The simulation analysis using general algebraic modeling system(GAMS) shows that, (a) the model presented can optimize the inter-regional generation cost and environmental cost to a certain extent; (b) clean energy plays a more important role in the optimization of inter-regional energy allocation than fossil fuel energy by comparing the results of inter-regional energy allocation optimization with and without clean energy generation; and (c) the difference of carbon emission prices in regions will influence the benefit achieved by the energy replacement of clean energy and fossil fuel energy.

Abstract:Switch allocation is a critical stage of router pipelines for On-Chip Networks, whose performance influences the overall performance of a router and even the whole NoC greatly. However, the existing time-series based switch allocation mainly is considered in canonical five-pipeline router architecture, and the researching in low-latency router is absent. So this paper made the first attempt to implement the time-series based switch allocation in low-latency router, and made improvement based on the construction features of priority matrixes in switch allocating. Simulation experiments results show that the combining time-series switch with low-latency router can greatly improve the performance of state-of-the-art NoCs.

Abstract:As manufacturing technology for Integrated Circuit (IC) enters into 28nm technology node， the number of transistors on chip keeps on growing dramatically all the time，and interconnect delay has become one of the major obstacles of timing closure for IC designs. This paper proposed a physical-aware long-interconnect optimization methodology. The main idea of the proposed methodology is that: key cells/elements for long-interconnect delay optimization are identified and placed at place stage in EDA tools; And then，timing delay is optimized by adding/deleting buffer cells. The proposed methodology provides a solution to the problem of long-interconnect optimization issue for VLSI design in EDA tools. Experimental results indicate that:1) the quantity of buffers to be inserted can be guided by the interconnect distance between the key elements and optimized according to the specific design requirements，and using ×8 buffer between the distance in 200 μm and 250 μm can obtain the most effective effect;2) substituting the buffers with inverter-pairs can reduce the total interconnect delay dramatically by 10%; 3) using wide metal can further reduce interconnect delay for 20~30 ps.

Abstract:Today, the many-core processor based on NoC(Network-on-Chip) is becoming the focus of high performance processor design. While migrating to many-core era, traditional debug architecture is no longer suitable for modern high performance processors. Especially, there are several challenges in the field of debug system for many-core processors, such as trace recording and transferring, debug events broadcasting, timestamp synchronization, and so on. To overcome these challenges, this paper presented an independent debug framework for many-core processors. In the proposed framework, high frequency and high throughput debug channels can be achieved at low connection cost. Moreover, debug components in the framework are distributed and symmetric, and it can be used for further processors with much more cores. On trace transferring, we provided a bandwidth balanced architecture for non-intrusive trace exporting. To reduce the complexity of hardware design, it cooperates with software to configure the weight of trace channel for arbitration. On debug events spreading, we established an event broadcasting network which owns the same topology with NoC and is easy for physical implementation. Meanwhile this network possesses low propagation delay. On timestamp synchronization, we provided a new precise timestamp synchronization method using debug network and independent wires with low hardware cost.

Abstract:BLAS library is the fundamental linear algebra library and plays an important role in many large scientific applications. This paper developed a linear algebra library named FitenBLAS on a massively multithreaded FT1000 processor. Based on the hierarchical storage system and the number of registers, multilevel loop unrolling methods were developed for vector-vector, matrix-vector and matrix-matrix linear operations. The codes of FitenBLAS were optimized with instruction layout and data prefetching technology. An avoiding redundant packing method was proposed for parallel matrix-matrix multiplication, and the parallel code was developed. The kernel matrix-matrix multiplication code was optimized with instruction layout, time overlapping of data access and computation, and data blocking. The other BLAS3 subroutines were designed on the matrix multiplication code. The kernel codes of FitenBLAS were developed in assembly language. The performance for the key subroutine of the matrix multiplication reaches 6.91Glops/s, nearly 86.4% of the peak performance of the FT1000.

Abstract:With the improvement of the performance of the supercomputer, the scale of the system becomes larger and larger, and how to monitor and manage the system efficiently becomes one of the key issues to be urgently solved for the high-performance computer. This paper proposed a monitoring and management system for the large-scale computer system called MMS (Monitoring and Management System). In MMS, the efficiency was improved by using the distributed system architecture, and the data processing was designed subtly to decrease the effect of the MMS on the computing network, which made the response time of the web client fast at the same time. The theoretical analyses and experiment results show that the MMS is efficient and reliable.

Abstract:This paper proposed a new water army accounts detection algorithm by analyzing the water army posting behaviors on online forums. The algorithm has three steps. The first one is to locate the suspicious periods by analyzing the daily reply behaviors of forum users, the second one is to build user collaborative networks based on user reply behaviors, and to locate the most suspicious periods by analyzing the pruned user collaborative networks, the last step is to detect the real water army accounts by analyzing the users' reply times. This algorithm excluding normal users and shrinking calculation ranges for 3 times has a small amount of calculation and high speed. We used this algorithm to analyze the dataset of Sina forum on 2010, and the results show that this algorithm can not only detect single water army account but also detect water army corps, and can determine the content of water army speculation．

Abstract:Vehicle transport network congestion control in the field of ITS is one of the main means to solve the problem of network congestion. By using a bottom-up agent modeling method, a multi-objective routing decision agent model was constructed to solve the problem. In the model, vehicles were simulated as mobile agents, which determined the routing decision dynamically by a two-objective optimization: the shortest travel distance and the minimum congestion degree of the road network. The multi-objective routing decision model could improve the congestion intersection, and on the other hand, could dig out the common features of congestion intersection to help the network congestion control. The simulation results show that the model can improve road network congestion. And the simulations to compare the effect of network structure with different link densities and link distribution on the road network congestion distribution further indicate that link density of the road network has no effect on the location of the emergent congestion intersections in the network, and the intersection location affects the degree of congestion. It also indicates that the link distribution of the network has a direct effect on the location of the emergent congestion intersections in the network and congestion optimization results.

Abstract:Aiming at solving the problem of the times of measurements, a scheme of sequential compressed sensing based on wavelet packet was proposed. The wavelet packet transform was firstly employed and the image was decomposed into wavelet packet blocks with the same size. The length of the initial sampling signal was then estimated using the relationship between the mathematical expectation and the sparsity of wavelet packet blocks. Meanwhile, the lengths of sampling signals were set dynamically in order to reduce the reconstruction and communication overhead. The problem of uncertain times of measurements in the traditional compressed sensing was thus overcome. Experimental results show that our proposed scheme has less reconstruction times and lower reconstruction error than the existed ones.

Abstract:To address the limitations of the traditional wavelet threshold denoising function, an improved wavelet threshold function was proposed. The improved threshold function not only has good continuity but also overcomes the lack of the non-negative dead zone threshold function and considers the characteristic of the attenuation of the noise wavelet modulus values. In addition, the use of spectral flatness function corrects the threshold values adaptively. The simulation results have showed that the improved wavelet threshold can eliminate ground noise effectively, maintain higher speech quality and definition while improving the signal to noise ratio (SNR) of the output.