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百年期刊
ISSN 1000-0585
CN 11-1848/P
Started in 1982
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Table of Content
, Volume 57 Issue 12
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COMPUTER SCIENCE AND TECHNOLOGY
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Two-dimensional routing based inter-domain traffic engineering model
XU Mingwei, GAO Bingjie
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1233-1238. DOI: 10.16511/j.cnki.qhdxxb.2017.21.022
Abstract
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Traffic engineering (TE) optimizes the allocation of resources. Inter-domain TE aims to balance the load of inter-autonomous system links and to optimize the utilization of every link. Internet routing is based on the packet destination address which limits BGP-based inter-domain TE when the network is congested. Typical inter-domain TE environments and requirements were analyzed to develop a TE model based on two-dimensional routing, a traffic placement algorithm and a source addresses splitting algorithm. Simulation show that the 2D-based inter-domain TE can successfully solve the fine-grained traffic split problem with better throughput and path stability than the traditional BGP TE.
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Link on-off prediction based multipath transfer optimization for aircraft
JIANG Zhuo, WU Qian, LI Hewu, WU Jianping
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1239-1244. DOI: 10.16511/j.cnki.qhdxxb.2017.21.021
Abstract
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The two main technologies used for aircraft internet access are satellite and air-to-ground (ATG) communication systems. When an aircraft flies over areas with overlapping signals, communicating with multiple paths may greatly improve transmission performance. This paper presents an optimization scheme for multipath transmissions in such aircraft multiple access scenarios. The slow link state discovery rates and inefficient data scheduling are improved by a link on-off prediction based data scheduling algorithm. The severe out-of-order condition caused by a long link round trip time (RTT) and loss rate differences is improved by transmitting a data level negative acknowledgement with all subflows from the receiver so that the sender can quickly identify and retransmit lost packets. Simulations show that this method is better than existing mechanisms for both the aggregated bandwidth and the average number of out of order packets.
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Information diffusion blocking model of node influence-oriented in online social network
ZHAO Yu, HUANG Kaizhi, GUO Yunfei, ZHAO Xing
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1245-1253. DOI: 10.16511/j.cnki.qhdxxb.2017.25.061
Abstract
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Information diffusion blocking maximization is used to select and delete the best
l
nodes (edges) to minimize the number of nodes receiving information in the network. However, the model does not take into account the node's influence which blocks the information flow and lowers the efficiency. This paper presents an information diffusion blocking model that considers the node's influence with a method based on the sampling average approximation (SAA). The model is selects and deletes the best
l
nodes to change the network structure which minimizing the influence of the target nodes. The model is a stochastic optimization problem which is transferred into a deterministic problem using SAA. The problem is then encoded as a mixed integer programming (MIP) problem. Finally, a quantum genetic algorithm is used to select the best
l
nodes and remove them. Simulations show that the best
l
nodes selected by this model influence the information diffusion over a smaller range and the processing time is shorter than the traditional model.
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Undulating scale of intonations of exclamatory Uyghur sentences
Hankiz Yilahun, Gulmire Imam, Maynur Ablitip, Guljamal Mamateli, Askar Hamdulla
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1254-1258. DOI: 10.16511/j.cnki.qhdxxb.2017.21.025
Abstract
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The speech of four Uyghur speakers selected according to their age and other information were tagged and segmented using the COOL EDIT PRO2.0 and PRAAT software.The results were used to investigate the pitch variations in the statement transfer domain and tone group transfer domain. The results show that the tone contours of exclamatory sentences always step down from the beginning to the end of the statement. Moreover, there is a slightly rising pitch at the end of the exclamatory statement as an obvious feature of exclamatory statements in the Uyghur language.
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Prosody modeling for Uyghur TTS
Gulmire Imam, Guljamal Mamateli, Maynur Ablitip, Askar Hamdulla
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1259-1264. DOI: 10.16511/j.cnki.qhdxxb.2017.21.026
Abstract
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The prosodic features of syllables such as duration, energy, mean pitch, maximum pitch, minimum pitch and pitch range were extracted from a Uyghur text to speech (TTS) database with analyses of their variations for different prosodic hierarchies. The pitch reset, pre-boundary lengthening, and silence duration of different prosodic boundaries were also analyzed. The results of acoustic experiments show that the pitch reset and pre-boundary lengthening are much greater as the prosodic boundary degree increases. No obvious pause can be perceived at the prosodic word (PW) boundary and the average silence duration at the prosodic phrase (PP) and intonation phrase (INP) boundaries are 154.2 and 212.8 ms.
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AUTOMATION
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Hill tunneling method via peak subpoints for continuous piecewise linear programming
XU Zhiming, LIU Kuangyu, BAI Yu, WANG Shuning
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1265-1271. DOI: 10.16511/j.cnki.qhdxxb.2017.25.059
Abstract
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Continuous piecewise linear (CPWL) optimization is a widely used mathematical programming method, and searching for the globally optimal solution is the research emphasis. This paper presents a heuristic algorithm with determinacy for the global optimization of CPWL programming, which is referred to as the hill tunneling via peak subpoint (HTPS) algorithm. A CPWL programming problem can be transformed into an equivalent concave optimization problem over a polyhedron; thus, the current algorithm makes use of the concavity of the super-level sets of concave piecewise linear functions to escape a local optimum to search on the other side of its contour surface by cutting across the super-level set. Each searching path for the hill tunneling is established using the peak subpoint of the "hill" shaped concave objective function. Numerical tests show that this algorithm is more efficient and has better global search capability than CPLEX or the hill detouring (HD) method, which shows its superior performance.
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Fault detection in HVAC systems based on energy balances
YANG Wen, ZHAO Qianchuan
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1272-1279. DOI: 10.16511/j.cnki.qhdxxb.2017.25.058
Abstract
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The air conditioning equipment and sensors in heating, ventilation and air conditioning (HVAC) systems can fail which is one of the main causes of building energy waste and risks to the safe operation of the HVAC system. A fault detection method based on energy balances was developed based on an HVAC energy network model. Energy conservation is then used to detect faults. The method analyzes the energy transfers for the air flows, the waterflows and the measured data in the distribution system in a global correlation across multiple systems. The method can simultaneously detect air conditioning equipment failures, sensor failures, and cross-system failures involving the power distribution. An example shows that the method is simple and easy to implement.
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AUTOMOTIVE ENGINEERING
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MPC based longitudinal coordinated collision avoidance for multiple connected vehicles
HU Manjiang, XU Biao, QIN Hongmao, XU Cheng, DING Ke, WANG Jianqiang
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1280-1286. DOI: 10.16511/j.cnki.qhdxxb.2017.21.032
Abstract
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The rapid development of vehicle collision warning systems has improved the road traffic safety. Current collision avoidance strategies, however, solely focus on the relationship between two consecutive vehicles, while ignoring the influence of avoidance strategies on the traffic flow behind the vehicle. A longitudinal coordinated collision avoidance (CCA) strategy was developed based on model predictive control (MPC) for multiple connected vehicles. The model considers multiple vehicle flow dynamics to minimize the total relative kinetic energy density (RKED) as the objective with and the optimization problem in continuous time discretized into a quadratic programming problem for numerical calculations to avoid or reduce the total loss of vehicle collisions. The effectiveness of this method is verified by MATLAB simulations.
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Target recognition around a vehicle based on an ultrasonic sensor array
XIN Zhe, ZOU Ruobing, LI Shengbo, YU Jiaying, DAI Yifan, CHEN Hailiang
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1287-1295. DOI: 10.16511/j.cnki.qhdxxb.2017.21.033
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Road traffic safety can be improved by detection and recognition of vehicle environment information. This paper describes a method for recognizing the environment target type by an ultrasonic sensor array. A high performance classifier is used in an object type discrimination algorithm for real-time target detection and identification. Three general shapes are identified as planes, cylinders and triangles by a support vector machine (SVM) classification model. The target shape is then extended to more specific features. The classification algorithm also gives the probability of each object at that moment. Simulations show that the classification models are 91.5% accurate which demonstrates that the object type discrimination algorithm can recognize environmental objects near the vehicle. In road test, the experimental platform collected data on road objects, such as vehicles, pedestrians and cyclists with good recognition accuracy.
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ELECTRICAL ENGINEERING
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Resource optimization for D2D communications based on statistical QoS provisioning
MI Xiang, ZHAO Ming, XU Xibin, WANG Jing
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1296-1302. DOI: 10.16511/j.cnki.qhdxxb.2017.21.028
Abstract
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(1176KB) (
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Device-to-device (D2D) communications are a key technology in fifth generation (5G) cellular networks. Resource allocation is critical to the D2D communication performance and is a key research topic. This study considers D2D communications in orthogonal frequency division multiple access (OFDMA) based cellular networks where the user delay requirements are characterized by the statistical quality-of-service (QoS) provisioning. An effective resource allocation scheme is given to maximize the QoS-guaranteed system throughput while guaranteeing the interference threshold requirements of the cellular users. The original optimization problem is solved using the Lagrange approach with algorithms based on an alternating optimization method and a successive convex approximation method. Simulations show that the resource allocation scheme significantly improves the system performance.
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Bridge detection in polarimetric SAR images based on water area tracing
LIU Chun, YANG Jian, XU Feng, FAN Yida
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1303-1309. DOI: 10.16511/j.cnki.qhdxxb.2017.25.057
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Bridges interfere with automatic segmentation and linking of waterways crossed by bridges. This paper describes an automatic bridge detection method using polarimetric synthetic aperture radar (SAR) based on tracing of known water areas. The water areas are first accurately extracted using a level set segmentation algorithm from polarimetric SAR images. All the water branches related to the bridge are then linked by the scanning and the tracing of the water areas. The feature points on the water branch contours are extracted to identify the bridge end points. The bridge bodies are then developed from the end points. The algorithm was tested using polarimetric SAR images from RADARSAT-2 over Singapore and Lingshui, China. The results show that the detection rate of this algorithm is very high. Even small bridges in large scenes are correctly identified by the algorithm.
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PRECISION INSTRUMENTS AND MECHANOLOGY
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Design of PCI express real-time measurement and control platforms for MEMS gyroscopes
ZHOU Bin, QIU Zhichang
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1310-1316. DOI: 10.16511/j.cnki.qhdxxb.2017.21.036
Abstract
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APCI Express (PCIe) real-time measurement and control platform was developed for micro electro mechanical system(MEMS) gyroscopes. The PCIe, the field programmable gate array (FPGA) driver and the delay link were optimized and accelerated to give closed-loop control of the gyro for both the driving frequency and the driving amplitude. Consequently, the linear vibration gyroscope operates at the resonant frequency and the amplitude is stable. The real-time performance and stability of the measurement and control system are analyzed. The FPGA hardware was optimized for the PCIe bus transmission. The single readout time was reduced to 1.8 μs by accelerating the bus transmission control and the PCIe IP core interface control. The driver was streamlined to reduce the data transmission delay between the kernel layer and the user layer. Efficient data transmission timing control stabilized the data transmission. The gyroscope operating frequency was then stable at 100 kHz.
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Dynamic model and dynamic characteristics of a 3-DOF spindle with a parallel linkage mechanism
YU Guang, WANG Liping, WU Jun, WANG Dong
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1317-1323. DOI: 10.16511/j.cnki.qhdxxb.2017.25.062
Abstract
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The dynamic characteristics of a machine tool are related to the ability of the tool to resist the dynamic loads which has an important influence on the machine tool cutting performance. This paper presents a model of the dynamic characteristics of a 3-DOF spindle with a parallel linkage mechanism. The valuable cross-section of the link in the spindle complicates an accurate defination of the mass matrix. This paper presents an approach to derive the mass matrix of a link with an arbitrarily shaped cross-section based on the finite-element method. The joint mass matrix is also considered in the model. The dynamic model is then used to investigate the natural frequencies and the vibration modes in the workspace. Tests on a prototype with the parallel linkage validate the model for accurate dynamic modeling of 3-DOF spindles with parallel linkages. This work is very useful for development of the 3-DOF spindle with parallel mechanism.
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THERMAL ENGINEERING
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Pseudo-component method for characterization of the thermochemical conversion of combustible solid waste
LONG Yanqiu, LI Qinghai, ZHOU Hui, MENG Aihong, ZHANG Yanguo
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1324-1330. DOI: 10.16511/j.cnki.qhdxxb.2017.25.056
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The treatment of combustible solid waste (CSW) is a critical environmental issue with thermochemical conversion regarded as a promising waste-to-energy (WTE) technology. The CSW properties that are relevant to the thermochemical conversion, such as the volatile content and the gross heating value, are required for incinerator design. This paper presents a pseudo-component analysis method using nine types of model components including cellulose, hemicellulose, lignin, starch, PE, PVC, PP, PS and PET to characterize the thermochemical conversion of the CSW waste stream. Each type of CSW can be represented by model components in terms of thermal mass coefficients obtained from TGA pyrolysis tests. The TGA curves of the model components were used to fit the curves for different types of CSW materials. Multiple linear regressions are used to acquire the thermal mass coefficients. The grey relation grade is used evaluate the accuracy. The average prediction error is within 5% for the volatiles and 10% for the gross heating value. This method provides a simple method for predicting the CSW properties for engineering designs.
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CIVIL ENGINEERING
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Fire spread simulations of building groups in rural areas
ZENG Xiang, YANG Zhebiao, XU Zhen, LU Xinzheng
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1331-1337. DOI: 10.16511/j.cnki.qhdxxb.2017.25.060
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Rural areas in southwestern China have high density building environments with mostly wooden structures with many fires in recent years. A fire simulation model was developed for a typical rural design to identify potential fire risks with a visualization platform based on the OSG (open scene graph) graphics engine. Visualizations of simulation results for Wenquan village and Dukezong city agree well with the actual fire hazard. This simulation method can be used to assist fire investigations, as well as to provide a scientific basis and technical support for fire prevention planning and fire control.
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HYDRAULIC ENGINEERING
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Recognizing construction worker activities based on accelerometers
QIANG Maoshan, ZHANG Dongcheng, JIANG Hanchen
Journal of Tsinghua University(Science and Technology). 2017,
57
(12): 1338-1344. DOI: 10.16511/j.cnki.qhdxxb.2017.25.055
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Automatic recognition of construction worker activities is key to real-time management of construction quality, safety and efficiency. An effective system requires the integration of many areas such as construction, information and management. Taking steel benders as an example, acceleration data from the wrists of steel benders was collected using accelerometers during the construction process. All activities were divided into three categories. The features were extracted from the acceleration data. Then classifiers were used to conduct machine learning with different features. The accuracies of different classifiers were compared to find the best classifiers and features. Tests demonstrate that the best features are related to the data segment length. Within a certain range, longer data segments give better recognition accuracy. This method gives more detailed classifications of the steel benders' activities with a recognition accuracy rate of 85.9% that is higher than previous methods. It provides a method for recognition of typical worker activities on site, and establishes a foundation for automated, real-time monitoring of construction workers to improve the quality, safety and efficiency of construction management.
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