最新刊期
卷 48 ， 期 12 ， 2020
- 摘要：To reveal the physical mechanism and establish the prediction model of the passive intermodulation (PIM) in the microstrip circuits, we deduce a closed form PIM model based on the dielectric nonlinearity through the dependent-source equivalence, and demonstrate that the dielectric nonlinearity is one of the major causes of PIM in microstrip circuits comparing the PIM phenomenon in PolyTetraFluoroEthylene (PTFE) fiberglass dielectric and air dielectric microstip lines. The nonlinear dielectric constant was derived as well. The experiments show that the PIM levels of the PTFE fiberglass dielectric microstirp line are about 20dB and 15dB larger than that of the air dielectric microstirp line for forward PIM and reverse PIM, respectively, which indicates that the dielectric nonlinearity is the main cause of PIM in the PTFE fiberglass based microstrip line. The third order nonlinear relative dielectric constant is deduced by the analytical PIM model. The model deduced in this paper can also be extended to study the PIM phenomenon in other microstrip circuits.关键词：dielectric nonlinearity;passive intermodulation;microstrip line;copper clad laminate;nonlinear dielectric constant193|346|0更新时间：2025-12-08
- 摘要：Big data applications provide convenience for people's life and work style, but in the process of data publishing, personal privacy information, such as consumption records, social relations, and so on, are collected by service providers all the time, and users' privacy is threatened greatly. Aiming at the significant relief of data processing pressure on single server, we propose a multi-cluster distributed differential privacy data publishing method based on neural network (MCDP), which effectively improves the prediction accuracy and efficiency, and different privacy parameters between clusters guarantee the flexibility of the protocol. Especially, because the central server stores statistical data after differential privacy processing, it does not collect individual privacy data, even if the central server is attacked, the user data will not be leaked. Experiments show that MCDP has obvious advantages in privacy processing efficiency, privacy protection intensity, prediction accuracy and prediction efficiency.关键词：data publishing;differential privacy;service collaboration;neural network;multi-cluster;distribution110|151|5更新时间：2025-12-08
- 摘要：Modeling the spatial magnetic field precisely is the basis for the geomagnetism-based indoor localization and tracking system. Traditional magnetic constructing schemes ignore the distribution of magnetic field, which causes low accuracy of the constructing magnetic field. To deal with this problem, this paper presents a magnetic field modeling method based on the gradient of the magnetic potential and Gaussian processes. Firstly, the relationship between the gradient of the magnetic potential and magnetic field is introduced into the Gaussian processes. Furthermore, the sum of the squared exponential kernel spatial gradient and geomagnetic offset field distribution variance is used as the kernel function of the Gaussian processes. By transforming the constrained hyperparameters optimization problem into an unconstrained optimization problem, we employ the Rprop algorithm to estimate the hyperparameters. Finally, simulations are implemented to analyze the advantage of proposed method over traditional methods, and the impact of the hyperparameters on magnetic discernibility is also discussed. In addition, we carry out magnetic field constructing tests using a triaxial vector magnetic sensor in different environments, including small area relatively strong magnetic field distorted environment, strong magnetic field distorted environment, and open area weak magnetic field distorted environment, to validate the performance of the proposed method in different real environments. The results of the experiments prove that the proposed scheme works well in practical applications.关键词：geomagnetism-based indoor localization;magnetic construction;Gaussian processes;gradient of the magnetic potential23|87|2更新时间：2025-12-08
- 摘要：Based on CRRC silicon carbide (SiC) process technology platform, 1200V high capacity SiC metal-oxide semiconductor field-effect transistor (MOSFET) device has been fabricated by adopting ion-implanted JFET region, the optimal termination design, gate bus-bar design and gate oxidation process. The fabricated SiC MOSFET is based on a planar gate structure. The test results show that the gate breakdown voltage of the device is above 55V and it achieves a relatively lower interface state density. At room temperature, the threshold voltage of the device is 2.7V. The maximum blocking voltage and the output current capability of fabricated SiC MOSFET is up to 1600V and 50A, respectively. At 175℃, the threshold voltage shift is less than 0.8V, and the gate leakage current of the device is less than 45nA when the gate voltage is 20V. All of the results show that the fabricated SiC MOSFET has superior electrical characteristics. It occupies a potential in high temperature and high power applications.关键词：SiC;MOSFET;gate bus-bar;JFET implantation;high capacity device;low leakage current;high temperature semiconductor35|61|4更新时间：2025-12-08
- 摘要：Sources and resultant radiations of extremely low frequency (ELF) electromagnetic waves can be effectively generated via modulated heating of the ionosphere by powerful high-frequency (HF) waves. With fundamental equations of magneto-hydrodynamics, the radiation field of the ELF radiation source in the ionosphere is derived. The dispersion relation of ELF waves propagating in the ionosphere is then obtained and the downward propagation attenuation model is established. According to this model, the differences of propagation attenuation in distinct latitudes and influences of transmitting frequency and ambient ionospheric parameters on propagation attenuation are analyzed. It is shown that the relative attenuation rate is raised with increase of the geomagnetic inclination and firstly rises and then falls with increase of the transmission frequency, resulting in an optimal transmission frequency value at which the relative attenuation rate reaches minimum. With enhancement of electron density or electron temperature, the relative attenuation rate rises and its growth rate drops.关键词：ionospheric radiation source;extremely low frequency;dispersion relation;relative attenuation rate;propagation attenuation model;attenuation characteristics40|70|0更新时间：2025-12-08
- 摘要：In order to improve the target tracking accuracy of multi-sensor system as well as solve the problem of long processing time due to the multiple sensors, a composite measurement IMM-EKF (Interacting Multiple Model-Extended Kalman Filter) data fusion algorithm is proposed. According to the measurement accuracy of each sensor, the algorithm weights and fuses the measurement of all sensors with respect to the same target, and performs the IMM-EKF filtering process on the merged measurement. The composite measurement IMM-EKF algorithm is compared with the weighted IMM-EKF algorithm and the extended dimension IMM-EKF algorithm in tracking accuracy and processing time through simulation and experiment data processing. The result shows that the extended dimension IMM-EKF algorithm has the best tracking accuracy while the composite measurement IMM-EKF algorithm needs the shortest processing time. The adapted occasions of the three fusion algorithms are given in the end.关键词：maneuvering target tracking;interactive multiple model;composite measurement;data fusion;multiple sensors;Kalman filter36|108|11更新时间：2025-12-08
- 摘要：Phase shifter is the core device of phased array radar (PAR). With the gradual increase of the working frequency, the insertion loss and phase control error of the traditional phase shifter get worsen seriously, resulting in additional power consumption and poor beam performance. In this paper, a high-precision digital phase shifting method based on CP-PLL is investigated. Based on the analysis of CP-PLL mathematical model and phase-shifting mechanism, the method of numerical control current source is proposed to realize the accurate control of the output signal phase, the circuit model is established to carry out simulation analysis, and the experimental circuit module is designed. The effectiveness and accuracy of the method are verified by the comparison of simulation and measurement. The results show that the phase-shifting step is better than 1°, and the accuracy is better than 10% of the phase-shifting value. The CP-PLL can be used in PAR as a local oscillator or as a direct transmitter signal. It has the characteristics of high precision, low power consumption and easy integration, which can replace the phase shifter and effectively improve the performance of PAR.关键词：phased array radar;phase shifter;charge pump phase-locked loop;digital phase shift;numerical controlled current source;integrated circuit28|67|0更新时间：2025-12-08
- 摘要：Wideband compressed spectrum sensing has the problems of unknown signal sparsity and high overhead of secondary users sensing. Therefore, this paper proposed an efficient cooperative scheme of wideband compressed spectrum sensing. Firstly, based on learning, a sparsity adaptive learning prediction model was derived. Secondly, a wideband spectrum filtering algorithm is designed. Finally, a cooperative wideband compressed spectrum sensing scheme was proposed. The simulation results show that the fitting effect of the adaptive prediction model are better than the existing prediction model, and the proposed sensing scheme effectively reduces the sampling rate and spectrum reconstruction delay of secondary users.关键词：wideband spectrum sensing;collaborative sensing;compressed sensing;sparsity estimation;supervised learning11|79|0更新时间：2025-12-08
- 摘要：Multi-label learning deals with the problem where each instance has a set of class labels simultaneously. In multi-label learning, label correlations have shown promising strength in improving multi-label learning. Most of the existing multi-label learning algorithms exploited either global label correlations shared among all instances, or local label correlations varied across different clusters of instances. In this study, we propose a novel multi-label learning method by simultaneously taking into account both the global and local label correlations to capture more comprehensive label information during the learning process. To calculating global and local label correlations, we utilize cosine similarity to obtain positive and negative correlations between different labels, which helps us to further achieve more reliable multi-label learning. We implemented extensive experimental comparisons based on various data sets to validate the effectiveness of our algorithm. The experimental results show that the proposed algorithm significantly outperforms most of the state-of-the art approaches, demonstrating its prominent performance for multi-label learning.关键词：multi-label learning;label correlations;cosine similarity22|89|2更新时间：2025-12-08
- 摘要：GNSS (Global Navigation Satellite System) spoofing equipment is the important components of "Navigation war". The valid evaluation of its effectiveness determines the success of the target task. However, there are still many difficult issues, such as the great ambiguity and uncertainty of influencing factors, the weak transitivity of influencing relations between factors, the poor applicability of assessment methods and the low evaluation efficiency. To deal with these problems, an evaluation method based on grey relational analysis and fuzzy comprehensive assessment is proposed. Firstly, the optimal scheme is obtained by calculating grey relational degree longitudinally. Secondly, the evaluation results of the optimal scheme are obtained by using fuzzy comprehensive assessment. Finally, the indexes highly correlated with the evaluation results are selected based on calculating gray relational degree horizontally. The test results show that these difficult problems are solved by the method proposed in this paper.关键词：navigation war;spoofing equipment;evaluation index;grey relational analysis;fuzzy comprehensive assessment19|49|10更新时间：2025-12-08
- 摘要：In the existing deep convolution neural network, the scale of receptive field is single, which could not adapt to the scale change and boundary deformation of the target. Therefore, a target detection network based on multi-scale feature extraction and feature fusion is proposed in this paper. The proposed network reduces pooling and adds space as well as channel compression excitation module at the bottom of the network to highlight the details and generate high-quality feature map. Besides, a variable multi-scale feature fusion module is added to the deep network, which has a multi-scale receptive field and can predict the position according to object boundary. Finally, the multi-scale feature fusion is used to enable the network of stronger ability of feature expression and is more robust to different scale and flexible boundary of instances. Experimental results show that the proposed structure achieves higher average accuracy than the original structure, and also has certain advantages compared with the state-of-the-art algorithms.关键词：object detection;feature pyramid network;deformable convolution;channel spatial squeeze excitation;multi-scale feature fusion19|442|8更新时间：2025-12-08
- 摘要：RF energy harvesting wireless sensor network (RFEH-WSN) consists of dedicated energy transmitter (ET) and sensor nodes with RF energy harvesting technology. The RFEH-WSN solves the problems of the battery replacement and node energy depletion, which makes it has more advantages in the future application. How to place ET effectively with minimum energy consumption and maximize overall charging utility is one fundamental issue in RFEH-WSN. In this paper, a new multiple object model is proposed, and the optimization aims of the model are to minimize the charging time and to maximize the coverage. An approximate with low complex algorithm is proposed to solve this multi-object function by PSO optimizer, and from it an optimum pareto solution set is obtained. The simulation results show that the new methods can improve the charging efficiency obviously and satisfy the different demands for lots of application environments.关键词：RF energy harvesting;wireless sensor network;PSO;MOP12|41|1更新时间：2025-12-08
- 摘要：Data storage is a basic operation of data management in wireless sensor networks. In mobile low-duty-cycle sensor networks, due to the mobility of the nodes, each node needs to frequently update the set of its neighbor nodes, which making energy consumption of the node too large. At the same time, each node is sleeping in most of its time, and wakes up to work in only a small portion of time. This sleeping/working mode results in excessive communication delay for data backup. A fast data storage mechanism with low energy consumption is proposed. First, each source node performs piecewise linear fitting compression on its sensing data based on continuous time series. Then, the node calculates a reasonable number of compressed data backups based on an estimated failure probability and the size of its storage space. On this basis, a dynamic adaptive transmission protocol is designed. Experimental simulations show that this mechanism has lower energy consumption of transmission and lower communication delay compared with existing storage algorithms.关键词：mobile low duty-cycle sensor networks;data storage;piecewise linear fitting compression;data backup;adaptive transmission12|34|0更新时间：2025-12-08
- 摘要：Moving object detection in complex scenes is an important problem in computer vision domain, and the detection accuracy is still a great challenge. In this paper, we propose and design a deep frame difference convolution neural network (DFDCNN) for moving object detection in complex scenes. DFDCNN consists of DifferenceNet and AppearanceNet, which can predict and segment the foreground pixels simultaneously without post-processing. DifferenceNet has Siamese Encoder-Decoder structure, which is used to learn changes between two consecutive frames and to obtain temporal information from inputs, while AppearanceNet is used to extract spatial information from the input frame, and fuse the temporal information and spatial information by fusion of feature maps. Finally, multi-scale spatial information is retained through multi-scale feature map fusion and stepwise up-sampling to improve the sensitivity to small objects. Experiments on two public standard datasets: CDnet2014 and I2R demonstrate that the proposed DFDCNN outperforms the classic algorithms significantly from both qualitative and quantitative aspects. The experimental results illustrate that the proposed DFDCNN shows much better detection performance in complex scenes where dynamic background, illumination variation and shadow exist, and there is improvement for scenes, in which small objects exist.关键词：moving object detection;complex scenes;deep frame difference convolutional neural network;temporal information;spatial information;multi-scale feature map fusion32|164|2更新时间：2025-12-08
- 摘要：For the new asymmetric paired carrier multiple access (APCMA) signal with the station signal bandwidth greater than the main station signal, on the basis of a low-complexity blind separation structure, an efficient blind separation algorithm based on the complementary symmetric filters is proposed. By constructing the complementary symmetric filters, the algorithm decomposes the mixed signal into two component signals in the time-frequency domain, one containing both the main station signal and the station signal, and the other containing only the station signal. Further,it separates the signal component containing the main station signal in the case of the same sample rate. Then, it synchronizes the two signal components under the same parameters, which ensures the additivity and integrity of the station signals in the two signal components after the separation. The experimental results show that compared with the original low-complexity separation algorithm, the proposed algorithm effectively improves the separation performance of the mixed signal. In addition, the complementary symmetric filters with information invariance proposed in this paper have a wide application prospect, which can be used in broadband multi-signal cancellation, channel estimation and spread spectrum detection under covert transmission.关键词：paired carrier multiple access;blind separation;time-frequency domain;complementary symmetric filters;information invariance10|38|4更新时间：2025-12-08
- 摘要：In complex networks, node importance identification plays an important role in analyzing the structure and function. In order to identify the node's importance and analyze the role of nodes themselves and associated nodes, we construct a node importance identification model based on importance transfer matrix. Firstly, the transmission capability between nodes is defined based on the optimal path length, the number of optimal paths and the information propagation rate between the associated nodes and the nodes. Secondly, the node degree and transmission capacity are used to construct the importance transmission matrix, and the local importance and global attribute index of the node are integrated to evaluate the importance of the node. Finally, destructive simulation analysis on the "ARPA" network and four real networks show that this method causes more damage to the network, which proves the method's effectiveness and reliability.关键词：complex network;node's importance;information transmission rate;transmission capacity;importance transfer matrix12|55|6更新时间：2025-12-08
- 摘要：Considering that the single shot multibox detector (SSD) algorithm will be missed or even false when it is used to detect the small and medium-sized objects, an improved SSD object detection algorithm is proposed to improve the accuracy of small and medium-sized objects detection. The details in the detection process are visualized with gradient-weighted class activation mapping (Grad-CAM) technology, and the details of each detection layer are shown in the form of class activation maps. Then it is noted that the phenomenon of the false or missed detection of the objects to be detected on small and medium-sized objects in the SSD algorithm is related to the regression loss function. Accordingly, Kullback-Leibler (KL) border regression loss strategy is adopted and non maximum suppression (NMS) algorithm is used to output the final prediction boxes. Experimental results show that compared with the existing detection algorithms, the improved algorithm in this paper has higher accuracy and stability.关键词：object detection;visualization;class activation maps;Grad-CAM;SSD;KL loss28|181|4更新时间：2025-12-08
- 摘要：To solve problems like path explosion, low rate of new path's finding in the software testing, a new vulnerability discovering architecture based on file format constraint (FFCBSE) was proposed. FFCBSE analyzed program source code to extract file structure constraints automatically. FFCBSE then used these structure constraints to guide symbolic execution to focus on core functions. This architecture was implemented in KLEE, and it was evaluated on seven file processing applications, such as Tcpdump, Readelf, File, Zlib. Compare with KLEE and DASE, FFCBSE detects thirteen previously unknown bugs. In addition, FFCBSE increases instruction line coverage/branch coverage by 10%~225%.关键词：symbolic execution;file format constraint;path explosion;bug finding18|37|0更新时间：2025-12-08
- 摘要：In the "many-to-one" concurrent traffic pattern of the data center networks, TCP (Transmission Control Protocol) and its existing improvements have low throughput in single-round and multi-round of data transmission scenarios. Hence, a strategy called TSL (TCP SkyLine) is proposed for fast discovering and retransmitting the lost packets through packet labelling and adjusting the initial size of the congestion window dynamically. TSL solves the traditional TCP Incast problem and the TCP Incast problem caused by the legacy window in multi-round of data transmission. Through extensive experiments we show that TSL can achieve more than 90% goodput regardless of single or multiple rounds of data transmission. In a 10Gbps network, the number of concurrent connections supported by TSL has increased by 5 times and once respectively compared to the traditional TCP and DCTCP, and the goodput has increased by 18 times and 8.6 times respectively. In a 1Gbps network, the number of concurrent connections supported by TSL has increased by 5.8 times and once respectively compared to the traditional TCP and DCTCP.关键词：data center;transmission protocol;TCP Incast;delay ACK;retransmission timeout;multi-turn transmission21|33|1更新时间：2025-12-08
- 摘要：The processing of graph data is restricted by large scale and complex structure. The graph summarization is to find a set of simple hyper-graphs or sparse graphs that clarify the main structural information or change trend of the original graph. According to the principle of minimum description length (MDL), a summary model based on edit coding is proposed for attribute graphs, which unifies the similarity of structure and attribute as storage cost to construct editing behavior code. Based on this model, a greedy algorithm and a random algorithm are proposed, which store the editing information of attribute and structure, generate high-quality hyper-graphs, and support the reconstruction of original graphs. The experimental results show that the proposed model and algorithms in this paper have some advantages over other summarization algorithms in terms of compression rate and time cost.关键词：graph summarization;edit coding;hyper-graph;visualization11|220|0更新时间：2025-12-08
- 摘要：Vehicle re-identification is the task of identifying the same vehicle across some images captured by multiple cameras. We propose a coupled feature clusters embedded into triplet loss dealing with hard samples. During the vehicle re-identification, the coupled clusters loss suffers from larger computation consumption caused by the extension of the sample scale and the reduction of identification accuracy. Therefore, the coupled feature clusters embedded into triplet loss is proposed. It improves the ability of the algorithm on processing hard samples in terms of selecting feature centers of positive samples based on clustering and the embedded into a triple loss. Experiments show that the algorithm effectively improves the accuracy of vehicle re-identification compared to the vehicle re-identification algorithm based on coupled clusters loss.关键词：vehicle re-identification;visual appearance;coupled feature clusters loss;triple loss11|62|1更新时间：2025-12-08
- 摘要：In this work, we proposed a hyperspectral unmixing method based on the spectrally weighted collaborative sparsity and the total variation, aiming at alleviating the lack of the sparsity of abundance in traditional methods and fully exploiting the spatial information. On the one hand, the spectral factors are utilized to estimate the weights in order to enforce the sparsity of nonzero rows, thus improving the collaborative sparsity among all the pixels. On the other hand, the total variation based spatial regularization is employed to reinforce the smoothness within the homogenous regions, hence improving the accuracy of unmixing. The model is solved by the well-known alternating direction method of multiplier, in which the spectral factor based weights and the abundance coefficients are iteratively optimized using both the internal and external loops. The experimental results obtained from the simulated and the real datasets indicate that the proposed method could significantly improve the performance of unmixing compared to the other state-of-the-art methods.关键词：hyperspectral imaging;sparse unmixing;spectral weighted collaborative sparse regression;total variation (TV);spatial information12|43|2更新时间：2025-12-08
- 摘要：Cellular automata (CA) based S-boxes are the type of S-boxes with good cryptography and low cost of hardware as well as software implementation, which are used in Keccak, SIMON, and other cryptographic algorithms. This paper studied the properties of CA-based S-boxes, and the three important properties were given and proved, including shift invariance, mirror symmetry and complementarity. Meanwhile, the neural network implementation for CA-based S-boxes was studied, which demonstrated that the CA-based S-boxes could be implemented with simpler structure and less resources than the general one. In addition, a weight threshold search algorithm which could easily and quickly implement the neural network structure of CA-based S-boxes was shown.关键词：cellular automata;S-boxes;Keccak;neural networks;weight and threshold;search algorithm10|42|2更新时间：2025-12-08
- 摘要：Epilepsy is a recurrent cerebral disease,and electroencephalogram (EEG) provides a non-invasive way to identify epileptogenic sites in the brain. In order to distinguish focal and non-focal epilepsy EEG signals, this paper proposes an automated epileptic EEG detection method based on variational mode decomposition. Firstly, the original signals are divided into several sub-signals, which are decomposed into intrinsic mode functions by using the variational mode decomposition (VMD). Furthermore, refined composite multiscale dispersion entropy (RCMDE) and refined composite multiscale fuzzy entropy (RCMFE) are extracted from each intrinsic mode function. Finally, the support vector machine (SVM) is used to classify characteristics. For an epilepsy EEG signals' public data set, the final experimental performance measures of accuracy, sensitivity, and specificity reach 94.24%, 95.58% and 90.64% respectively, and the area under the ROC curve is 0.978.关键词：epileptic electroencephalogram;variational mode decomposition;refined composite multiscale dispersion entropy;refined composite multiscale fuzzy entropy;support vector machine14|53|7更新时间：2025-12-08
- 摘要：With the successful application of deep learning algorithms in the field of image segmentation, a large number of excellent algorithm architectures have emerged in the direction of image instance segmentation. These architectures surpass the traditional methods in terms of segmentation effects and running speed. This paper focuses on the latest research progress of image instance segmentation technology, summarizes the current classic network architecture and cutting-edge network architecture, and uses common datasets and authoritative evaluation indicators to compare and analyze the segmentation effects of each architecture. Finally, the challenges and possible development trends of image instance segmentation technology are prospected.关键词：deep learning;image segmentation;instance segmentation38|405|20更新时间：2025-12-08
- 摘要：At first, a design and simulation of a RF power amplifier is presented. Then, the thermal characteristics analysis model of the RF power amplifier is built and the thermal characteristics of the RF power amplifier is analyzed by using the finite element method. After that the effects of increasing the through hole and different copper coating thickness, environmental temperature and dissipative power on the temperature, thermal stress and thermal deformation of the RF power amplifier are studied. Based on the above analysis, the RF power amplifier is fabricated and measured at last. In the frequency range of 3.3GHz to 3.6GHz, power added efficiency is from 62.6% to 69% with output power greater than 39.2dBm and gain larger than 12dB. When the ambient temperature is 21℃, the maximum temperature of the RF power amplifier reaches 90.0℃, and the test results are close to the simulation analysis results. The research of this paper provides important guidance for the design and manufacture of RF power amplifier in the future.关键词：RF power amplifier;thermal analysis;temperature;thermal stress;thermal deformation14|49|1更新时间：2025-12-08
- 摘要：In order to improve the performance of single-phase full-bridge inverter, a novel single-phase full-bridge inverter with a resonant DC link is proposed. The auxiliary circuit in the DC link can improve the steady state value of the DC bus voltage, and reduce the negative effect of DC bus zero-voltage state on DC voltage utilization. In this paper, the commutation process of the inverter is analyzed. The experimental results show that the switching devices achieve soft switching, and the performance of the inverter is improved.关键词：inverter;auxiliary circuit;soft-switching;boost;DC voltage utilization15|35|1更新时间：2025-12-08
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