最新刊期
卷 50 ， 期 10 ， 2016
- 摘要：An improved method(IODSRA)to measure omni-direstional spatial rotation angles is proposed to focus on the problem, that the analytical approach for measurement of spatial angle with dual-axis inclination sensor can't measure the omni-directional rotation angle. It is based on the space model that measurement axis of inclination sensor rotates around measurement axis of rigid body, and the method improves the sensitivity of measuring angles and obtains spatial position parameters by applying a single axis inclinometer in the direction of normal vector of existed sensor. The optimal rotational angle measurement is acquired by taking full advantage of several rotation equations. Experimental results show that the IODSRA method achieves the measurement of the omni-directional spatial rotation angle while other algorithms are unable, and that detection accuracy can be controlled under 0.2° and meets requirements.关键词：angle measurement;omni-directional rotation angle;inclinometer;space rotation model;spatial position parameter770|4|0更新时间：2025-07-09
- 摘要：A method to generate BBA(basic belief assignment)based on cluster analysis is proposed to focus the problem that the mass function is hard to determine when the frame is unknown. The method tackles the situation whether the frame of discernment is known or not. A clustering analysis method is applied to extract cluster features and models of cluster features are constructed with the samples. Then the distances between different cluster feature models are calculated to represent differences between sample attributes and then the similarities of them are obtained. Finally, the values of similarities are normalized to get the BBA. The analysis results of classifying the Iris dataset and Wine dataset show that the proposed method is less dependent on the length of samples and the classification accuracy in Wine dataset is 100%. Monitoring information series by applying the method to a compressor unit system proves the effectiveness of the method, and the condition of monitoring information can be clearly recognized.关键词：evidence theory;basic belief assignment;cluster feature interval model;similarity;information fusion666|4|2更新时间：2025-07-09
- 摘要：A numerical method of equivalent conductivity based on a gradient model is proposed to evaluate the effect of surface roughness on the equivalent electrical conductivity of metal surface at microwave band and experimental verification of the method is performed. Firstly, it is based on the gradient model of conductivity that the surface of a rough metal is equivalent to the superposition of several smooth thin layers. Secondly, the loss and transmission characteristics of the electromagnetic wave in each thin layer is based to calculate the total loss of the rough metal surface and to obtain the equivalent surface conductivity. Finally, the resonant cavity with replaceable end plate is used to measure the surface conductivities of machined brass samples with various roughness at 8.98 GHz and 10.78 GHz, respectively. Results indicate that, the equivalent conductivity decreases as the roughness increases for samples with RMS roughness in the range of 0.1-3 μm and that the theoretical predicted value of the equivalent conductivity from the proposed numerical method has a better agreement with measurement results than that from existing theories.关键词：microwave frequency band;root mean square roughness;resonant cavity632|4|0更新时间：2025-07-09
- 摘要：At the present there lacks proper optimization method for internal dielectric properties of dielectric functionally-graded-material(d-FGM). An optimization algorithm of internal permittivity distribution for multi-layer permittivity FGM(ε-FGM)insulator under AC voltage is proposed, which aims at weakening the maximum electric field(e-field)strength along the insulator surface. According to design parameters, such as current e-field strength, objective e-field value and permittivity range, the permittivity value of each layer is self-adaptively updated with iterations to obtain the optimized permittivity distribution. The iterative coefficient and shrinking coefficient are adjusted to control the convergence process and shorten calculation period. Compared with uniform insulator, e-field distribution inside and along the surface of ε-FGM insulator is more uniform and the maximum e-field strength along surface is weakened more than 60%, and the layer thickness of the multi-layer ε-FGM insulator ought to be set as small as possible under the allowed fabrication conditions. The maximum surface e-field strength decreases nonlinearly with the increasing permittivity upper limit and saturates as the upper limit reaches certain threshold value, which has positive correlation with the maximum e-field strength before optimization.关键词：solid insulation;functionally graded material;electric field distribution993|5|15更新时间：2025-07-09
- 摘要：To describe the dynamic process of electric arc on the arc run-on plate to yield the influencing law of the arc run-on end tab on the breaker interruption performance, an analysis strategy based on the interruption model of low voltage circuit breaker is proposed for arc movement on the arc runner with arc run-on end tab. Firstly, a multi-field coupled calculation model that enables to simulate the interruption process of low voltage circuit breaker is constructed. Secondly developing the multi-body dynamic simulation software ADAMS, a set of differential equations describing the coupling relations among electric circuit, magnetic field, puffer effect, complex mechanical movement and dynamic arc model are established. This model is used to simulate the arc movement process undergoing arc striking, moving, transferring and extinguishing. The influences of different structures of arc run-on end tabs on the interruption performance of low voltage circuit breaker are analyzed and verified by the tests. Both calculation and experiment results demonstrate that the hook-like arc run-on end tab has a larger contact area than the flat end tab towards the arc movement direction, that the arc angle of the hook-like end tab bends to the direction of splitter plates conforming to the overall movement trend of the electric arc, and the arc root on hook-like end tab is thus easier to jump onto the arc run-on plate than on the flat end tab to consequently decrease the contact erosion.关键词：low voltage circuit breaker;arc run-on end tab;interruption model824|4|6更新时间：2025-07-09
- 摘要：For the battery-supercapacitor(SC)hybrid power source(HPS)with a boost converter, the supercapacitor voltage(i.e. output voltage)might be unstable and the battery current(i.e. input current)fluctuation might be very high. To solve these problems, an adaptive sliding-mode control strategy is proposed. A dynamic model of the battery-SC HPS with the boost converter is established by combining the conventional averaged model of the boost converter and the characteristics of the SC. It is based on the model that an adaptive estimator is designed to estimate the related parameters, and adaptive rules are defined according Lyapunov function. Furthermore, a suitable sliding surface is selected and a duty ratio function is designed according to the selected sliding surface and the adaptive rules. Observe gains are also designed in accordance with the constant current/voltage control requirement in the HPS. An experimental platform is established. Experimental results show that the proposed strategy makes the system reach steady state quickly. A comparison with the PI control strategy in the conditions of both constant current control and constant voltage control shows that the strategy improves the transient time by 88.8% and 62.5%, respectively. It effectively eliminates the fluctuation of the output voltage and inductor current, and improves the safety and reliability of system when the SC voltage is lower.关键词：boost converter;hybrid power source;adaptive sliding-mode control;supercapacitor651|4|7更新时间：2025-07-09
- 摘要：To reduce the complexity of gear hobbing error model, establish a mapping relationship between the machine tool error model and the machining precision, and accurately identify and predict gear hobbing error, a method is proposed where the complete error model of gear hobbing is divided into two completely independent submodels for cooperative computing, and the maneuverability of the error model for gear hobbers is improved for engineering application. The deviations in transmission model are evaluated by homogeneous coordinate transformation. Following the space meshing principle of the conjugate surfaces in gear hobbing, the ideal tooth surface functions are calculated. By means of tooth profile conversion, the profile error of gear tooth from the deviations in transmission model and the actual tooth profile are obtained. The errors of gear profile, lead and index can be obtained through comparison. The complete mapping relationship between the machine tool error and the machining error is thus established. A hobbing experiment of a spur gear with hob eccentric error shows that the prediction from this model and detection from the experiment coincide well, verifying the correctness and availability of this model, and the relative error is no more than 5%. The accurate error identification and prediction make virtualization for gear hobbing possible, and provide significant technical support for the construction of machine tool cyber-physical system to realize of predictable manufacturing.关键词：gear hobbing;complete error model;null-coupling;space meshing theory;error prediction;machine tool cyber-physical system679|4|0更新时间：2025-07-09
- 摘要：A fast scale estimation algorithm for visual tracking with feature integration is proposed to solve tracking failure from object scale changes. The gradient feature and color feature are integrated to obtain more object representation information with the increasing feature dimensions, then a fast multi-scale feature pyramid method is used to approximate the adjacent scale features to get templates in different scales, thus it is possible to balance the computation cost due to the increasing feature dimensions without accuracy loss after approximation. Combining tracking results of multi-scale templates, the object location and scale are estimated accurately by the proposed algorithm in the framework of correlation tracking 4 representative video sequences with scale changes, and illumination variations and background clusters are chosen to simulate. The experiments indicate that the proposed algorithm well adapts to environmental variations and outperforms the traditional scale-adaptive kernel correlation tracking schemes in center location error, overlap ratio, precision and success rate.关键词：object tracking;correlation filtering;scale-adaptive;fast feature pyramids750|4|5更新时间：2025-07-09
- 摘要：A grouping mapping mechanism of threads is proposed to reasonably map application threads to specific processing cores of a many-core processor according to the characteristics of applications. The mechanism bases on the data locality of intra-thread and the data correlation of inter-threads, and combines with the features of hardware architecture of many-core processor. The locality of intra-thread data is analyzed by computing the data reuse distance, and the correlation of inter-threads data is quantified by using a affinity matrix. Threads are divided into different logical groups by designing an algorithm to generate affinity spanning subtree. The reasonable mapping from application to core is realized by binding the thread to the processing core. Experimental results and a comparison with a traditional mapping mechanism show that the proposed mapping mechanism obtains nearly 14% improvement in computing performance and 12% reduction in energy consumption without introducing additional runtime overhead. The mechanism reasonably maps application threads to specific processing cores of many-core processors, and improves computing efficiency of many-core systems.关键词：many-core system;thread mapping;data affinity;data reuse distance;logical thread grouping640|4|1更新时间：2025-07-09
- 摘要：A new automatic scoring method based on multi-feature analysis is proposed to focus the problem that there are a great number of C/C++ programming learners on massive open online courses environment, while the existing automatic scoring techniques possess low accuracy. The prompt information in a submitted program is eliminated with a preprocessing compiler. The lexical analysis and abstract syntax tree(AST)methods are used to extract the features of the submitted program and the standard template one, respectively. Then similarities of these features are calculated. According to whether or not the program is compiled successfully, two different strategies are applied to comprehensively analyze the multi-feature similarities and the program is automatically evaluated finally. The multi-feature similarities include the running result similarity of test cases, the AST feature similarity, and the source code similarity. If the program fails to be compiled, both the source code similarity and the AST features similarity need to be analyzed. Experimental results and comparisons with the dynamic test method and the static analysis method show that the average accuracy of the proposed method increases by 18.38% and 14.17%, respectively. The automatically generated scores are highly correlated with manually determined scores and there is no manual assistant to ensure the accuracy of the scoring results. The proposed method can be applied in massive open online courses.关键词：massive open online courses;automatic evaluation;multi-feature analysis;abstract syntax tree;similarity computation533|4|0更新时间：2025-07-09
- 摘要：A novel hybrid cloud and fog network architecture based on edge computing is proposed to solve the problem of high processing latency of the medical big data in cloud computing network. The architecture adds a fog computing layer between cloud servers and medical measurement devices by using edge devices such as routers or switches in a hospital. Fog computing devices proactively cache analysis results of medical images and other medical big data from cloud servers, and compare these data with the data from medical measurement devices to get the diagnostic results and reduce processing latency. Meanwhile, a multi device distributed computing scheme is proposed by considering the weak computing power of edge devices and a constrained particle swarm optimization load balancing(CPSO-LB)algorithm is applied to minimize the latency. Simulation results indicate that the novel network architecture with CPSO-LB algorithm decreases the latency effectively. A comparison with a cloud computing shows that it's latency performance increases by 50.95%-37.37% when 10 fog devices and processing 6-10 Gb medical data are used.关键词：medical big data;cloud computing;hybrid cloud/fog network;load balancing1015|4|10更新时间：2025-07-09
- 摘要：A weighted local structured Hashing(WLSH)method is proposed to address the problem in the field of image retrieval that most existing Hashing methods only consider the global information and treat each projected dimension equivalently, which leads to a problem that the binary codes cannot efficiently preserve the data similarity. The proposed method considers local structure information of original image data and the variance of each projected dimension simultaneously. An affinity weight matrix is built to describe the relationship between data points and to acquire local structure information of the original image data. Then, an iterative quantization is used to find an optimal orthogonal transformation matrix and to minimize the quantization error. Finally, a weighted matrix is used to balance the variances and to guarantee equivalent information of each Hashing bits, thus the data similarity is effectively preserve. Experimental results based on some large scale datasets show that the precision and recall of the WLSH algorithm are improved by 3% and 2% over principal component analysis-iterative quantization, respectively.关键词：projection functions;local structure information;iterative quantization;balance the variance;image retrieval730|4|1更新时间：2025-07-09
- 摘要：An optimal coverage control algorithm with joint sensing(OCCAJS)is proposed to solve the problem of rapid consumption of network energy resulted from the large number of redundant nodes in the process of wireless sensor network coverage. The algorithm presents the solving process of maximal seamless coverage in the case of joint coverage of three nodes. Two methods are given, one calculates the expectations of coverage quality when sensor nodes are covered in the monitoring area and the other determines coverage rate when the expectation of a sensor node is compared with those of neighbor nodes. Moreover, when redundant coverage exists, the calculation process of the coverage rate for any sensor node in redundant coverage is presented by using ratio quotient. Simulation results and comparison with some existing algorithms in coverage quality and network lifetime show that the proposed algorithm improves the average performance about 11.02% and 13.27%,respectively. The proposed algorithm not only improves the coverage quality, but also suppresses the rapid consumption of nodes energy and the network lifetime is prolonged.关键词：wireless sensor network;coverage quality;nodes joint;network lifetime721|4|4更新时间：2025-07-09
- 摘要：A path optimization algorithm for autonomous underwater vehicles is proposed to solve the problem of the shortest distance with not the lowest energy consumption in the traditional path optimization algorithm. The algorithm bases on an improved ant colony algorithm with optimal energy consumption. A stress model of movement process of AUV in water is built by studying the hydrodynamic analysis of AUV and a formula to calculate the energy consumption of AUV moving path is derived. Then, the improved ant colony algorithm with optimal energy consumption is presented. The inverse of the path energy consumption is used as a path pheromone value to guide evaluation of ant colonies by energy consumption. Experimental results show that the proposed algorithm uses 22 iterations to plan a 433.51 m long path with 12 235.17 J AUV energy consumption, while a traditional algorithm uses 33 iterations to plan a393.65 m long path with 12 864.99 J AUV energy consumption. The path distance planned by the proposed algorithm is 10% longer than that planned by the traditional algorithm, but it's energy consumption is lower by 5%. It is clear that the algorithm has advantages of reducing the energy consumption and improving the battery life.关键词：energy consumption;ant colony algorithm;autonomous underwater vehicle;distance664|4|13更新时间：2025-07-09
- 摘要：A new speed regulation circuit driven by a YVF-multi-output pump is proposed to deal with problems that there exist energy loss in general motor-multi-output pump speed regulation circuits,and the YVF-constant single pump speed regulation circuit has the disadvantage of poor dynamic response and its output flow is restricted by the allowable range of pump speeds. The proposed circuit saves energy loss of general motor-multi-output pump speed regulation circuits through the stepless speed control of YVF. The range of output flow is expanded without changing the allowable range of pump speeds, and multiple speed characteristic lines are obtained through the step speed control of multi-output pump. Theoretical analysis shows that there is no energy loss in new circuit, and the minimum output flow decreases as the displacement ratio of multi-output pump increases and the maximum output flow increases as both the ratio and the action number of multi-output pumps increase. The results of AMEsim simulation show that the proposed circuit meets the dynamic responses of different working conditions and improves the adaptability of the speed regulation circuit through selecting different speed characteristic lines.关键词：hydraulic speed regulation circuit;variable frequency speed regulating;multi-output pump;speed characteristic;energy saving;dynamic response565|4|2更新时间：2025-07-09
- 摘要：A 10-stage rotor model with 10 circumferential tie rods in uniformly distribution is proposed to optimize the rod structure and to improve the operation safety of the rotor with tie rods in gas turbines. It is based on the model that a series cases of rod shoulder clearances are set, and the relationship among the stress of the tie rod and the rotational speed, and static installation clearance is investigated using a three-dimensional nonlinear contact finite element method. Then the effects of two improvement plans(double the shoulder number with equal and unequal span respectively)on stress reduction are compared at the same static installation clearance. Moreover, the effect of the span value on the stress of the tie rod is studied while the shoulders are uniformly arranged. Results show that the clearance between the rod shoulder and rod hole has no relationship with the rod stress at a normal operation condition, but affects the maximum stress when rotor speed increases. There exists a specific change rule of the maximum stress of the tie rods in different speed range. The maximum stress of the tie rod is effectively reduced by properly adding the amount of the rod shoulders to reduce the span. The effect of stress reduction obtained by adding the rod shoulder number uniformly is better than that obtained by adding the rod shoulder nonuniformly. The results provide references for the design of the rotor with tie rods in gas turbines.关键词：gas turbine rotor;tie rod;rod shoulder;stress;design improvement1007|4|2更新时间：2025-07-09
- 摘要：The joint allocation of transmission mode and resource is considered, and two mechanisms are proposed to address the problem of the severe mutual interference between mobile relay(MR)assisted device-to-device(D2D)communication and the existing cellular communication whether each MR can be reused by multiple D2D links. The problem model of interference is reduced into a bipartite matching problem in mechanism 1 when each MR can be reused by multiple D2D links, and the optimal solution of the problem is obtained in polynomial-time by using Hungary algorithm. The problem model of interference turns out to be a three-dimensional matching problem in mechanism 2 when each MR cannot be reused by multiple D2D links. The problem generally is NP-hard, and a heuristic algorithm is proposed to get its approximate optimum in polynomial-time. The results show that the proposed mechanism 1 maintains the optimal performance and outweighs the greedy scheme by 29.94%, and mechanism 2 achieves a 23.67% gain compared with the greedy scheme, and that a comparison with the optimal algorithm shows the proposed schemes attain polynomial-time complexity with only 8.16% performance loss.关键词：device-to-device communication;mobile relay;mode selection;resource allocation518|4|1更新时间：2025-07-09
- 摘要：A collaborative filtering recommendation algorithm using the multiple groups intelligence is proposed to address the problems that most of the current recommendation systems that are based-on social networks use the general heuristic methods and have drawbacks of choice of complex paths and weak transferring of trust phenomenon which leads to low recommendation precision, and there exists the inherent cold start problem in recommendation systems. The proposed algorithm divides users into several different groups from their social attribution and social trust relationship information Then predictive models are built based on multi-group through analyzing the user's social activities and social relationships in the groups and the evaluated group scores are used to predict ratings of new users The algorithm uses a deep group mining in a social network, the multi group intelligence to effectively improve the effect of the recommendation, and the evaluated group score to improve the recommendation of the cold start users. Simulation results and comparisons with the traditional collaborative recommendation algorithm and other social recommendation algorithms show that the recommendation effects of the proposed algorithm improve by about 0.2 and 0.22, respectively, and that the problem of cold start is effectively solved.关键词：collaborative filtering recommendation;social network;group intelligence;cold start632|4|1更新时间：2025-07-09
- 摘要：Aiming at the issue of the frequency instability of emergent light from diode lasers in Littman configuration, a stabilization method combined F-P cavity with phase-locked amplifier is proposed. The laser frequency is stabilized to the resonance frequency corresponding to the average cavity length of a F-P cavity. A function generator is used to drive the F-P cavity according to the sinusoidal signal, and a photoelectric detector is used to transform optical signals passing through F-P optical cavity into electrical signals. The electrical signals frequency mix with drive signals from function generator and then pass trough low pass filter in the phase-locked amplifier to get optical cavity resonance signal phase error. The signal is given back to laser by PID controller to stable optical frequency through the feedback selection of internal current and external cavity PZT driving voltage. We theoretically deduce the correlation between optical cavity resonance signal phase error and the laser wavelength, and then choose the standard deviation of the F-P optical cavity transmission peak time interval value τ as a frequency stability evaluation index. Experiments show that the stability of external cavity semiconductor laser frequency is improved by 80% via feedback selection of external cavity PZT driving voltage. This method is simple and efficient to be applied to different wavelengths and longtime laser frequency stabilization.关键词：frequency stabilization;F-P optical cavity;phase locking;Littman configuration646|4|2更新时间：2025-07-09
- 摘要：To reduce the computing time of fluid structure coupling, an efficient dynamic mesh method based on the pre-existing elastic solid method is developed. The flow mesh domain is assumed to be a pseudo elastic solid according to the basic hypotheses of the elastic solid method, then the structure and the pseudo elastic solid are considered together as one holistic system. Subsequently the natural frequencies and vibration modes are calculated for the system and the flow force acted on the structure is considered as the excitation of the holistic system. The nodal displacements for the structure and the flow mesh are computed by mode superposition. In fact, the actual fluid structure coupled vibration for structures often appears associated with low order modes, the nodal displacements of the flow mesh can be calculated by modal superposition of the first few of low order modes, thus the flow mesh can be updated efficiently. A beam flutter problem is discussed with the present dynamic mesh method. The results coincide well with the data reported in the existing reference verifying the validation of the present method. The computing time is reduced by 65.5% compared with the pre-existing elastic solid method. The flutter of wing 445.6 is also analyzed and the calculated flutter boundary agrees with the experimental data, and the computing time is reduced by 54.8%.关键词：fluid structure interaction;elastic solid method;efficient dynamic mesh method651|4|4更新时间：2025-07-09
- 摘要：A Timoshenko beam model with fewer degrees of freedom(DOFs)by isogeometric analysis method is proposed to be applied to active control of the flexible rotor and is numerically verified. This strategy solves the difficulties in the model from the standard FEM analysis, which cannot be directly employed for controller design due to the more DOFs. The isogeometric beam model with the semi-discrete form and the various boundaries are considered as the input signals in the active control for the rotor, then the singular value responses of the isogeometric beam models with more and fewer DOFs are compared, and the numerical solutions of isogeometric beam models with more and fewer DOFs and theoretic solutions both with simple supports are also compared. The rotor supported by the magnetic bearing and under the disturbances by the given distributing unbalance forces is simulated by the decentralized PD method. The results show that the singular responses of the model with fewer DOFs almost agree with those with more DOFs within the range of the sixth critical speed; the numerical solutions with more DOFs agree well the theoretic solutions within the first ten modal frequencies and the relative error of the first four modal frequencies from the model with fewer DOFs is less than 0.2%; the deviation of the steady displacement responses from the unbalance vibration between the isogeometric models with more and fewer DOFs is small and their steady response deviation can be regarded as the small disturbances with the same frequency at the working speed. The feasibility of applying directly for controller design is verified by the higher accuracy of the fewer DOFs isogeometric beam model within the low frequency range.关键词：isogeometric method;flexible rotor model;Timoshenko beam;vibration control;magnetic bearing731|4|0更新时间：2025-07-09
- 摘要：To improve the filling capacity of slurry and integrity of ceramic mold in process of fabricating the integral ceramic mold based on stereolithography, a negative pressure injection method is proposed, which focuses on small cooling holes of hollow turbine blade. The gel-casting filling process is investigated following the filling principle for a long and thin tube. A numerical simulation is carried out to reveal the effect of negative pressure injection on the mold filling capacity of slurry in small and complex structures, and the suitable pressure difference between the import and export is obtained. The negative pressure injection experiment and industrial CT detection are performed to verify the simulation results. The effect of negative pressure injection on the performance of ceramic mold is analyzed. It is found that the small cooling holes of hollow turbine blade can be duplicated without defects when the solid loading of alumina ceramic slurry possesses 60% and the pressure difference between the import and export reaches 0.03 MPa, and the density and strength of the green ceramic mold can be improved.关键词：stereolithography;hollow turbine blade;cooling hole;negative pressure injection;ceramic mold697|4|2更新时间：2025-07-09
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A Calibration Method of Error Parameters for Dual-Axial Rotary Strapdown Inertial Navigation Systems
摘要：A new systematic calibration method is proposed to solve the problems that current modulate methods can only modulate parts of parameters of dual-axis rotary modulation strapdown inertial navigation systems and their speeds are slow, and to realize the fast self-calibration of all gyroscopes errors of dual-axis rotary modulation strapdown inertial navigation systems The method compensates errors to improve the accuracy of navigation systems. At first, it is based on the error compensation fundamental and mechanical structure of dual-axis rotation SINS that equations of gyroscopes errors are deduced when both the inside and outside axes are in any direction at initial time. Then, the calibration route is designed through observability analysis, and dimension error parameters are finally acquired by filter. The method can rapidly calibrate all gyroscopes errors by just using the self rotating mechanism without external standard. The method overcomes the shortages of existing methods that only calibrate part of all parameters, and cuts down calibration time effectively. Simulation results show that the method realizes the calibration of all parameters of gyroscopes errors just in 6 minutes while existing methods cost tens of minutes to calibrate, and that the method is fast and feasible.关键词：strapdown inertial navigation system;rotary modulation;systematic calibration;observability analysis;all parameters591|4|3更新时间：2025-07-09
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