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ISSN 1000-0585
CN 11-1848/P
Started in 1982
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  • Table of Content
      , Volume 56 Issue 9 Previous Issue    Next Issue
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    ELECTRONIC ENGINEERING
    Image salient region detection by fusing clustering and ranking
    LIU Jie, WANG Shengjin
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 913-919.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.059
    Abstract   PDF (1317KB) ( 815 )
    Salient region detection is an extremely challenging problem in computer vision. Most salient region detection algorithms determine the saliency of pixels in the image by directly computing the contrast between a pixel or a patch and its neighborhood within a certain range. When the image background is cluttered or the background and the salient objects in the image have some of the same image features, the detection capabilities of these traditional methods are decreased. A salient region detection framework based on re-clustering is used here. First, a clustering algorithm is used to group superpixels into a number of superpixel clusters by automatically computing the scale parameter and the number of clusters. The algorithm automatically selects possible background clusters from the superpixel clusters with the selected clusters used as queries in a ranking algorithm to obtain the final saliency map. Tests on two public salient region detection datasets show that the algorithm gives stable salient region detection results with better performance metrics than five other algorithms.
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    Man-made target detection in polarimetric SAR images using the Riemannian kernel Fisher criterion
    GAO Wei, YIN Junjun, YANG Jian
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 920-924,929.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.055
    Abstract   PDF (2032KB) ( 783 )
    Detection of man-made targets is essential for automatic interpretation of polarimetric synthetic aperture radar (SAR) images. This paper describes a man-made target detection method that utilizes the Riemannian kernel Fisher criterion. The kernel function is constructed by means of a Riemannian metric defined on the manifold of Hermitian positive definite matrices. The polarimetric covariance matrices are mapped into the high-dimensional feature space induced by the kernel function and then discriminated by the Fisher criterion. This method takes into account the special matrix structure of the polarimetric SAR data and does not assume any statistical models; therefore, it is particularly suitable for detecting man-made targets in polarimetric SAR images. The effectiveness of this method is verified in the context of ship detection. Tests show that this method outperforms other detectors, especially for low target-to-clutter ratio.
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    Adaptive partial decode-and-forward of Turbo codes for OBP satellites
    LI Hang, GAO Zhen, ZHAO Ming, WANG Jing
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 925-929.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.056
    Abstract   PDF (1091KB) ( 663 )
    An adaptive partial decode-and-forward (APDF) algorithm was developed for on-board processing (OBP) for the high processing complexity Turbo decoder with limited processing resources. This algorithm reduces the number of iterations to lower the resource consumption. The adaptive algorithm contains an upper level where the range of iterations is determined by the link quality and an inner level using an early stopping criterion to reduce computations. The two levels of adaption are combined to decreases the average number of iterations while the performance is improved compared with the partial iterative decode method with fixed iterations.
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    Key technology and application of the energy internet based on cyber physical systems
    SHI Chenbo, MIAO Quan, CHEN Qixin
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 930-936,941.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.061
    Abstract   PDF (1737KB) ( 1848 )
    Many new internet systems and patterns are being developed that will positively influence the development and use of renewable energy. The rise of the third industrial revolution based on the energy internet will use cyber physical systems (CPS) combining information, communication and sensors integrated with energy systems in the electrical grid. The resulting cyber energy systems can optimize renewable energy use; however, the integration of CPS and energy systems is not well understood. This paper describes the structure and characteristics of the energy internet. The internet and energy systems are integrated for the production, transmission, storage and sharing of energy. The new application and recent trends in the energy internet are discussed along with challenges and suggestions on how to promote the system development.
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    CapEx-minimized incremental network design based on multi-core fibers
    LI Yao, HUA Nan, ZHENG Xiaoping
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 937-941.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.048
    Abstract   PDF (1232KB) ( 605 )
    Incremental design is needed to increase the network capacity and provide better network performance to satisfy the growing traffic demands in optical networks. Multi-core fibers can multiply the fiber density and provide much more transmission capacity compared with single-core fibers. This article investigates the CapEx minimization problem for multi-core fiber based incremental optical networks. The CapEx-minimized incremental network design is obtained by solving an integer linear programming model of the optimization problem. The results show that properly deploying of both multi-core and single-core fibers and network topology augmentation will minimize the network CapExs.
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    Effects of Chinese sign language modality on processing sentences
    YAO Dengfeng, JIANG Minghu, ABUDOUKELIMU Abulizi
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 942-948.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.050
    Abstract   PDF (1521KB) ( 819 )
    The effects of Chinese sign language (CSL) modality on processing sentences are investigated by using the event-related potential method to focus on the influence of both semantic and phonological information on the lexical accessment during sentence processing and its timing. The semantic expectancy and phonetic form of the target signs with the final inflections are manipulated during stimuli selection in the test design. The electroencephalogram data of 18 native CSL signers were recorded and analyzed. The sign perception evidence (100-200 ms) reflects the process of mapping the primary visual features into the phonological features of the signs. This was followed by two negativities associated with matching the phonological features of the target sign with contextual information (200-400 ms) and the dynamic construction of the semantic restriction of the discourse context (400-650 ms) that promoted integration of the lexicon and sentence context. The phonological and semantic-related signs shared a similar timing pattern and the effect direction verified the similarity of the semantic and phonological properties access and the similar online processing cost of CSL and ordinary Chinese sentence comprehension. An N300 effect was found that uniquely indicates the successful processing of phonetic features in the sign language modality. This effect represents the direct link between the phonological feature recognition and the sign recognition. The results show that the subject considers the match between context and target sign as a priority, rather than the phonological features of the signs. This result indicates the interaction between the phonological and semantic-related information at the moment of lexical selection.
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    COMPUTER SCIENCE AND TECHNOLOGY
    Cyberinfrastructure prototype for seafloor observations
    LI Xiu, OUYANG Xiaogang, TANG Youhua, HUANG Rongsheng, MA Hui
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 949-955.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.047
    Abstract   PDF (1552KB) ( 630 )
    The cyberinfrastructure (CI) for seafloor observations needs to integrate multi-resource heterogeneous data, process massive amounts of data and foster cooperation to construct the seafloor observation network. Integration of distributed computing resources, storage resources, data resources and sensors in the system architecture is needed to provide network based computational services, massive data processing services and research opportunities for specific users. This paper shows how to integrate the scientific workflow and develop the data analysis modules for the massive data processing. A virtual organization is then used to achieve web-based research cooperation. Tests show that the prototype dramatically improves the efficiency of marine researchers.
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    Dynamic taint tracking in JavaScript using revised code
    WANG Weiping, BAI Junyang, ZHANG Yuchan, WANG Jianxin
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 956-962,968.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.063
    Abstract   PDF (1470KB) ( 1027 )
    The rapid development of the web has led to increasing use of JavaScript, especially in websites requiring rapid responses between the web server and the client, which has led to many security problems. This paper presents a dynamic taint tracking method based on a revised JavaScript code. The revised code can mark and track sensitive data transmission paths during JavaScript execution and warn the user of possible leakage of the marked sensitive data. This implementation is independent of the JavaScript engine and can be used in a variety of browsers. Tests show that this method can effectively track sensitive data and detect abnormal behavior.
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    Cholesky decomposition and parallel structure design based on matrix triangularization decomposition
    LIU Shuyong, LIN Junyu, WU Yanxia, ZHANG Bowei
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 963-968.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.060
    Abstract   PDF (1331KB) ( 1009 )
    Matrix computing is one of the core problems in high performance computing with matrix decomposition being an important way to improve the parallelism of matrix computations. FPGA gives a powerful environment for parallel computing. This study uses Cholesky decomposition based on a hardware-adaptive parallel sub-matrix identity updating algorithm. Its parallel structure is based on FPGA. Tests show that this structure achieves more than 10 fold speedup compared to general-purpose processors in terms of the kernel computational speed because the algorithm has better data-parallelism and pipeline-parallelism during matrix triangularization.
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    AUTO MATION
    Multiple model fusion in 3-D reconstruction: Illumination and scale invariance
    CHEN Baohua, DENG Lei, DUAN Yueqi, CHEN Zhixiang, ZHOU Jie
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 969-973.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.046
    Abstract   PDF (2639KB) ( 877 )
    3-D internet photo visualization reconstructs objects in 3-D using structure information gained from the object's motion to give users motion experience. However, due to the large illumination difference between photographs on the Internet, traditional reconstruction methods cannot generate a single point cloud, but will generate multiple independent point clouds. This paper describes a 3-D model registration framework based on 3-D geometries that generates unified 3-D models from various illuminations to complete a structure from multiple models. The 3-D point cloud geometry is used instead of the 2-D features to overcome the influence of large illumination changes. Secondly, a scaled-PCA-ICP algorithm was then used to do the registration that can overcome the large scale variance between the two point clouds. Tests on two datasets show the effectiveness of this method.
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    Component-based multi-resolution dynamic structure modeling and simulations
    PENG Gongzhuang, MAO Huachao, ZHANG Heming
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 974-979,984.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.049
    Abstract   PDF (1963KB) ( 748 )
    In complex system simulations, the models adaptively change in accordance with the outward environment, which can lead to consistency and concurrency problems. A component-based multi-resolution dynamic structure (CMDS) modeling and simulation approach was developed to improve these simulations. The model changes the structure from a high-level unified control model to a resolution state chart to achieve consistency with syntax consistency through port adaptive simulations. A algorithm is given to quickly reconstruct the CMDS system structure. Tests on a large simulation system with variable structures show that the CMDS approach can take advantage of models having different resolution and can quickly and accurately choose the appropriate model for the specific computing resources.
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    CIVIL ENGINEERING
    Out-of-plane elastic buckling analysis of box-section arches with lateral bracings
    ZHAO Siyuan, GUO Yanlin, WANG Hong
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 980-984.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.062
    Abstract   PDF (1166KB) ( 830 )
    Arches are usually arranged with lateral bracings to improve their out-of-plane stability. The out-of-plane elastic buckling of box-section arches was analyzed with a single lateral bracing on the crown. The energy method was used to derive the formulas for the out-of-plane buckling loads on lateral braced box-section arches for uniform compression or uniform bending. Then, the out-of-plane elastic buckling solution for arches with no lateral bracings was used to derive the threshold stiffness of the lateral bracings. The out-of-plane buckling loads and threshold stiffnesses of the lateral bracings given by this method agree well with finite element results and can be applied to calculate the the out-of-plane inelastic strength of box-section steel arches with lateral bracings.
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    Two-lane freeway intermittent release measures in heavy fog
    TAN Jinhua, SHI Jing
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 985-990.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.054
    Abstract   PDF (1441KB) ( 682 )
    Rear-end collisions easily occur on freeway during heavy fog. This paper presents a cellular automaton traffic model for two-way intermittent release of freeway traffic during heavy fog to quantify the influence of various measures on traffic accident reduction. Simulations show that the rear-end collision probability,fa, is reduced with longer time intervals,ht between released cars in heavy fog conditions. Then, different speed limits have different critical time intervals,hmax. Intermittent release measures can guarantee that no rear-end collisions occur when ht>hmax. However, both fa andhmax increase as the fog zone area expands and with asynchronous release in the two lanes. Therefore, freeway management can effectively control the rear-end collision risk through adopting suitable intermittent release measures from this study.
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    Experimental investigation of low-yield-point steel shear panel dampers
    XU Liyan, NIE Xin, FAN Jiansheng, LIU Fujun, LI Shengyong, HUANG Zhonghai
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 991-996.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.053
    Abstract   PDF (2684KB) ( 890 )
    Pseudo-static tests of three groups of shear panel dampers made of low-yield-point steel, BLY160, were conducted to study the hysteresis in the mechanical properties, low cycle fatigue behavior and earthquake mitigation effects. Two specimens were subjected to four loading schemes to investigate the influences of stiffening rib size, width-thickness ratio of the web plate and the cyclical load history. The results show that the low-yield-point steel has significant cyclic hardening with the accumulation of plastic strain and that the damping devices using BLY160 steel have high initial stiffnesses, small yield displacement, favorable ductility, stable hysteresis and excellent energy dissipation.
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    Data conversion and sharing for building performance analyses based on IFC
    LIN Jiarui, ZHANG Jianping
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 997-1002.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.057
    Abstract   PDF (1530KB) ( 1046 )
    An IFC-based data conversion algorithm was developed to automatically convert BIM model data to gbXML format for building performance information sharing. The IFC and gbXML data were mapped and related in an automatic conversion algorithm. The algorithm was validated with different project data sets to show that the algorithm allows performance information sharing among different stakeholders by eliminating reworking of the data models and improving efficiency.
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    MECHANICAL ENGINEERING
    Dynamics characteristics of collisions between fuel elements transported in tandem in a pebble-bed reactor system
    LIU Hongbing, HUANG An, CHANG Baohua, WANG Li, DU Dong
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 1003-1008,1015.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.058
    Abstract   PDF (2302KB) ( 638 )
    Spherical fuel elements are lifted pneumatically into an array of tubes outside the core in a pebble-bed reactor with the flow in the tubes perpendicular to the flow in the core. Sometimes two fuel elements are very close in the pipeline so they are transported in tandem, which increases the fuel element transportation efficiency. When lifted, the fuel elements may collide with each other with the characteristics of these collisions providing an important basis for evaluating the reliability of the transport system. This study analyzed the flow characteristics in the pipeline using computational fluid dynamics to determine the forces on the fuel elements. A dynamic model of the fuel elements was then developed to describe the impact characteristics. The results demonstrate that the collision force will not damage the fuel elements and that the fuel elements will be lifted together after several collisions. The lifting process is steady and the lifting is efficient. Experimental tests validate the accuracy of the theoretical analysis. This research provides a basis for designing pneumatic transport systems for fuel elements in pebble-bed reactors.
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    ENVIRONMENTAL SCIENCE AND ENGINEERING
    Extracellular polymeric substance (EPS) characteristics and comparison of suspended and attached activated sludge at low temperatures
    ZHOU Lü, XING Xiujuan, PENG Biao, FANG Guofeng
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 1009-1015.   DOI: 10.16511/j.cnki.qhdxxb.2016.21.051
    Abstract   PDF (2348KB) ( 838 )
    In biological wastewater treatment, the extracellular polymeric substances (EPS) composition affects the activated sludge stability, flocculation and biological metabolism. The EPS composition in different activated sludges (attached, suspended and hybrid) was measured at low temperatures (6℃ and 10℃) to analyze its influence on the biological adaptability and pollutant removal. A sequencing batch moving bed biofilm reactor (SBMBBR) and a sequencing batch reactor (SBR) were used in the lab scale tests. The results show that protein (PN) was the main ingredient in the sludge EPS with tightly-bound EPS (TB-EPS) having the highest proportion in the total EPS. The organic load and temperature change significantly affected the PN and PS (Polysaccharides) ratios as the mass per unit volume for different activated sludges, with the suspended sludge having lower PN/PS ratios than the biofilm sludge. At 10℃, the EPS production rate increased in the low organic load sludge, but at 6℃, the EPS contents in the attached, suspended and hybrid sludge increased with the organic load.
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    CHEMISTRY AND CHEMICAL ENGINEERING
    Economic performance design based on adaptive iterative learning control of MPC systems
    WANG Zhenlei, LIU Xueyan, WANG Xin
    Journal of Tsinghua University(Science and Technology). 2016, 56 (9): 1016-1024.   DOI: 10.16511/j.cnki.qhdxxb.2016.24.024
    Abstract   PDF (2636KB) ( 912 )
    An adaptive step iterative learning control (ASILC) strategy was developed for model predictive control (MPC) system economic performance design. The strategy treats the functional relationship between the variable variances and the controller parameters as a combination of discrete linear intervals and uses process information in the last iteration to adaptively update the iteration step. This optimizes the economic performance step by step. The method is used to design an ethylene cracking furnace control system. Simulations show that ASILC converges to the optimal operating point faster than iterative learning control (ILC) and obtains the controller parameter λ for the optimal economic performance. After seven optimizations and iterations, the economic performance target was improved 28.92%.
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