Search

Accurate forecast of citywide passenger demand helps online car-hailing service providers to better schedule driver supplies. Previous research either uses only passenger order history and fails to capture the deep dependency of passenger demand, or is restricted on grid region partition that loses physical context. Recent advance in mobile traffic analysis has fostered understanding of city functions. In this article, we propose FlowFlexDP, a demand prediction model that integrates regional crowd flow and applies to flexible region partition. Analysis on a cellular dataset covering 1.5 million users in a major city in China reveals strong correlation between passenger demand and crowd flow. FlowFlexDP extracts both order history and crowd flow from cellular data, and adopts Graph Convolutional Neural Network to adapt prediction for regions of arbitrary shapes and sizes in a city. Evaluation on a large scale data set of 6 online car-hailing applications from cellular data shows that FlowFlexDP accurately predicts passenger demand and outperforms the state-of-the-art demand prediction methods. [ABSTRACT FROM AUTHOR]

In September 1961, the first ruby laser successfully debuted at Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), Chinese Academy of Sciences (CAS), marking the beginning of laser science and technology in China. It operated with unique features about one year after T. H. Maiman’s first working model in the United States, and three months after the first laser in the former Soviet Union. It was unusual for China to achieve such an accomplishment given its technically backward state in the 1950s, and one cannot help but wonder how the Chinese scientists caught up with international trends in laser research. We want to answer some important questions about this historical event and explain the birth of the first ruby laser in China by examining the archives of the developmental process and interviewing some of the key members who pioneered China’s laser research. [ABSTRACT FROM AUTHOR]

The article presents an introduction to a paper about developments, current status and future prospects for ultra-high-voltage (UHV) transmission in China. The authors of the paper examined the accomplishments of the country in the field of UHV transmission research. Their aim is to enhance the safety and reliability of the future UHV grid in the country. Furthermore, they aim to provide a reference for other countries working to create similar UHV grid. One of the primary problems which complicate the country's attempts to distribute electric power more effeciently is the vastness of its electric grid system.

Sentiment analysis of microblog texts has drawn lots of attention in both the academic and industrial fields. However, most of the current work only focuses on polarity classification. In this paper, we present an opinion mining system for Chinese microblogs called CMiner. Instead of polarity classification, CMiner focuses on more complicated opinion mining tasks - opinion target extraction and opinion summarization. Novel algorithms are developed for the two tasks and integrated into the end-to-end system. CMiner can help to effectively understand the users’ opinion towards different opinion targets in a microblog topic. Specially, we develop an unsupervised label propagation algorithm for opinion target extraction. The opinion targets of all messages in a topic are collectively extracted based on the assumption that similar messages may focus on similar opinion targets. In addition, we build an aspect-based opinion summarization framework for microblog topics. After getting the opinion targets of all the microblog messages in a topic, we cluster the opinion targets into several groups and extract representative targets and summaries for each group. A co-ranking algorithm is proposed to rank both the opinion targets and microblog sentences simultaneously. Experimental results on a benchmark dataset show the effectiveness of our system and the algorithms. [ABSTRACT FROM PUBLISHER]

In this study, a locally weighted linear regression (LWLR) method is proposed to predict damping ratio of a dominant mode online. The LWLR method, which is nonparametric and data-oriented, is essentially proposed for nonlinear data fitting; therefore, it can track the nonlinear power system operations and help damping ratio prediction in real power systems, which is hardly achieved by the conventional linear regression. To successfully implement this method, the measurement of weighting value and the choice of weighting function as well as its parameter setting, related to prediction accuracy and numerical conditions, are extensively discussed. Simulations are carried out in a two-area four-machine system and a large complex system, China Southern Grid. Both results validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The successful management of crowdsourcing risk has gained considerable attention because of the challenges involved in obtaining the satisfactory performance from crowdsourcing activities. However, the mechanism of how various critical risk factors affect crowdsourcing performance has been poorly investigated. Empirical evidence based on a dataset of 169 samples from China shows that three technical (i.e., complexity, requirement, and task) and three social (i.e., seeker, solver, and relationship) subsystem risks not only directly but also interactively influence the crowdsourcing task performance. Technical subsystem risk factors, while worsen performance, diminish the negative effects of social subsystem risk factors on the crowdsourcing task performance. The diminishing effects of three technical subsystem risk factors are also differentiated. High requirement and task risks lessen the negative effects of seeker, solver, and relationship risks on the task performance, whereas the high complexity risk only weakens the negative effect of the solver risk. Therefore, various crowdsourcing risk factors affect the performance in different ways and directions (either negatively or positively). Risk can perform dual roles in influencing the performance. Hybrid strategies that integrate social and technical subsystem elements may be effective in achieving a superior task performance for the crowdsourcing risk management. Managers of crowdsourcing platforms can also optimize social and technical environments to improve the fit between social and technical systems. [ABSTRACT FROM AUTHOR]

Processing China Clay to increase its brightness is commercially important for the ceramics and paper industries. Quantum Design, Inc. has developed a high throughput conduction-cooled superconducting magnetic separation system which operates at 6 Tesla with a 10% uniformity over 406 mm. This long uniformity range, along with its 203 mm diameter bore and high magnetic field result in a single system capable of processing 10,000–15,000 tonnes of clay per year. This superconducting magnet is maintained at low temperature using a variable frequency driven Gifford-McMahon refrigerator, which dramatically reduces operating costs compared to a liquid helium cooled magnet ($40 to cool down at $0.10/kWhr). Furthermore, the small footprint of the system combined with the inexpensive operating costs allow for a modular design for systems to be combined specific to the needs of the China Clay mining facility. Testing has been carried out using various types of China Clay, also known as kaolin, from three different mines. Typical results show a reduction in Fe2O3 by over 60%. In particular, before processing, one sample contained 0.85 wt% Fe2O3 and a fired brightness of 88%. After processing in the Quantum Design SHGMS (Superconducting High-Gradient Magnetic Separator), the Fe2O3 content was reduced by 65% to 0.29 wt%, and the fired brightness increased to 92.5%, resulting in a three-fold increase in the value of the clay. [ABSTRACT FROM AUTHOR]

Due to the rapid urbanization of China, many villages in the urban fringe are enveloped by ever-expanding cities and become so-called urban villages (UVs) with substandard living conditions. Despite physical similarities to informal settlements in other countries (e.g., slums in India), UVs have access to basic public services, and more importantly, villagers own the land legitimately. The resulting socio-economic impact on urban development attracts increasing interest. However, the identification of UVs in previous studies relies on fieldwork, leading to late and incomplete analyses. In this paper, we present three scene-based methods for detecting UVs using high-resolution remotely sensed imagery based on a novel multi-index scene model and two popular scene models, i.e., bag-of-visual-words and supervised latent Dirichlet allocation. In the experiments, our index-based approach produced Kappa values around 0.82 and outperformed conventional models both quantitatively and visually. Moreover, we performed multitemporal classification to evaluate the transferability of training samples across multitemporal images with respect to three methods, and the index-based approach yielded best results again. Finally, using the detection results, we conducted a systematic spatiotemporal analysis of UVs in Shenzhen and Wuhan, two mega cities of China. At the city level, we observe the decline of UVs in urban areas over the recent years. At the block level, we characterize UVs quantitatively from physical and geometrical perspectives and investigate the relationships between UVs and other geographic features. In both levels, the comparison between UVs in Shenzhen and Wuhan is made, and the variations within and across cities are revealed. [ABSTRACT FROM PUBLISHER]

Telemedicine helps developing countries deliver medical services to underdeveloped rural areas where health resources are deficient. Yet telemedicine diffusion in the largest developing country, China, remains a secret to the world. This paper examines the evolution of telemedicine in China, analyzes factors influencing the diffusion of telemedicine, and provides recommendations to overcome obstacles to telemedicine. [ABSTRACT FROM AUTHOR]

In this work, firstly we propose an artificial neural network (ANN) based channel modeling and simulation framework to playback a measurement channel to overcome the shortcomings of traditional geometry based stochastic modelling (GBSM) and simulation approach which is unable to predict a time or position-varying channel to match with real environment. Secondly, we implement the framework based on channel measurements performed at 28 GHz in a large waiting hall at Qingdao high-speed railway station, China. Thirdly, we validate the proposed framework by comparisons of the large scale channel parameters (LSCPs) and small scale channel parameters (SSCPs) extracted from the measured, ANN and GBSM simulation channels. The results show that the ANN-based framework can playback the measured channels accurately, while GBSM-based simulated channels have large deviations. This work offers a solution to playback the measured channels accurately to be used in 5G and beyond radio system research and engineering applications, while it’s also able to be applied in future channel predictions in case of large amount of measured data available. [ABSTRACT FROM AUTHOR]

Line-commutated converter based high voltage direct current (LCC-HVDC) transmissions are widely applied in delivering large-capacity electricity in China. Multiple large-capacity LCC-HVDC transmissions strengthen dynamic coupling between AC and DC networks. Existing literature has reported some stability problems caused by dynamic interactions between AC and DC power grids, however, the mechanism behind these problems has not been totally understood and revealed. To analyze dynamic interactions between AC and DC power grids, this article presents a small-signal model to understand the external characteristics of LCC-HVDC stations based on the motion equation concept. Comparison of time-domain simulation response with the detailed switching model shows that the proposed model can hold main behaviors of concern. Dynamic interactions between AC and DC power grids are studied based on the proposed model in multi-infeed LCC-HVDC systems. Analytical results demonstrate that there exists power dynamics in receiving AC grid when sending AC grid subjects to a disturbance, and effects of converter stations’ controller parameters on power dynamics are explained by the physical relationship among state variables of the proposed model. [ABSTRACT FROM AUTHOR]

Room temperature vulcanized (RTV) silicone rubber is a type of anti-pollution flashover coating which has been widely used in China. Featuring good hydrophobicity and adhesive property, RTV coatings are applied to insulators to increase the pollution flashover voltage of insulator strings. However, compared with high temperature vulcanized (HTV) silicone rubber used in composite insulators, RTV coatings are less durable in field operation. In this paper, investigation and experiments were conducted on some RTV coated insulators from Shanxi province and Guangdong province respectively. All the insulators have been in operation for about 6 years and the RTV coatings applied are produced by the same manufacturer. It is found that the performances of RTV coated insulators in Shanxi province are much better than those in Guangdong province. Phenomena such as chalking, color fading and peeling off were observed on RTV coated insulators from Guangdong whereas only slight loss of adhesion property and hydrophobicity were observed on insulators from Shanxi province. Micro structural analysis and macro performance tests were conducted on different positions of collected insulators and it is concluded that operation environment, especially humidity, have great impact on the operation performance of RTV coated insulators. [ABSTRACT FROM PUBLISHER]

Ziyuan1-02C (ZY1-02C) was launched on December 22, 2011, and it is the first civilian high-resolution remote sensing satellite in China. However, the limited precision of the onboard attitude measurement system causes many errors during attitude transfer by ZY1-02C. Thus, there are complex distortions in the images obtained by ZY1-02C, which restricts its application greatly. In this paper, we consider the feasibility of attitude error correction based on parallel observations with high-resolution cameras, and the method is described in detail. To validate the efficiency of the proposed method, several images and corresponding control data were collected from the Henan, Taihang Mountain, Neimeng, and Taiyuan areas in China. The experimental results indicate that seamless mosaic images without distortion can be obtained using our method. Furthermore, the positioning accuracy with a few ground control points (GCPs) was shown to be better than 1.5 pixels and equivalent to the accuracy of the GCPs. [ABSTRACT FROM PUBLISHER]

Focuses on the electromagnetic launch (EML) technology research in China. Why EML launchers should be treated as an energy transformer; Background of the theoretical research in China.

The dynamic behavior of phasor measurement units (PMUs) is not only the key point to dynamic phasor algorithm improvement but also the basis for the successful implementation of PMUs in power system dynamic security monitoring and control. In this paper, the dynamic performance of PMUs is evaluated, and their dynamic behaviors are analyzed. PMUs from the four largest Chinese manufacturers are tested through the established PMU test system, and their dynamic performance is comprehensively evaluated. The dynamic behaviors of the PMUs are also analyzed. Analysis shows that the spectral leakage and the averaging effect of the discrete Fourier transform (DFT) under dynamic conditions are the key reasons that lead to their dynamic behaviors. The theoretical results are consistent with the experimental data and the simulation. Finally, to eliminate the spectral leakage, the DFT with a digital low-pass filter is adopted to obtain more precise phasor measurements. [ABSTRACT FROM PUBLISHER]

The power industry in China has grown significantly over the past decade, spurring the adoption of system-wide automatic voltage control (AVC) technology to meet stricter requirements for security and economical power system operation. To cope with the rapidly developing and frequently changing Chinese power grid, an AVC scheme based on adaptive zone division is introduced in this paper. Logically, this type of system has a three-level hierarchical structure, but, here, both secondary voltage control (SVC) and tertiary voltage control (TVC) are implemented via software at the same control center. The control zones are no longer fixed but are reconfigured online and updated in accordance with variations in the grid structure. The technical details of these procedures are presented here. The implementation of TVC (which is based on an online reactive optimal power flow) and SVC are also discussed, together with some technical details on improvements to their reliability and robustness. Some results obtained from field-site applications based on similar-days testing rather than simulations are employed to evaluate the performance and improvements of the AVC system. This system has been installed at over 20 control centers in China. [ABSTRACT FROM PUBLISHER]

This Special Issue of the Transactions in Plasma Science consists of selected papers from the Sixteenth International Symposium on Electromagnetic Launch (EML) Technology, held at the China National Convention Center in Beijing, China, May 15-19, 2012. This biennial symposium is the primary forum for presentation and discussion of research on critical technologies for the acceleration of macroscopic objects using EM or electrothermal-chemical launchers. This symposium was cohosted by the Institute for Strategic and Innovative Technologies (ISIT) and the China Electrotechnical Society (CES) under the sponsorship of IEEE?s Nuclear and Plasma Sciences Society, was attended by 151 researchers and engineers from 13 countries. The cochairs of the symposium were Dr. Harry Fair (ISIT) and Dr. Jun Li (Beijing Institute of Special Electromechanical Technology). In addition to naming the recipients of the Peter Mark Medal and the Fisrt Harry Fair Award, the author reviews the development of EML science and technology during the 1970s and 1980s focusing on the EML Technology Symposium, the first of which was held in San Diego, CA, in 1980. The proceedings were peer reviewed and published as a Special Issue of the IEEE Transactions on Magnetics. The EML Symposia have been held biennially ever since, and all of the EML Symposia have been published as special issues either of the Transactions on Magnetics or more recently in the Transactions of Plasma Sciences. These 16 IEEE issues form the fundamental science and technology base for EML technology. [ABSTRACT FROM PUBLISHER]

The MEdium Resolution Spectral Imager (MERSI) is the keystone instrument onboard FengYun-3 (FY-3). After FY-3A, FY-3B MERSI is the second launched in November 2010. Nineteen of the 20 MERSI spectral bands are the reflective solar bands, which cannot be absolutely calibrated onboard. The annual vicarious calibration (VC) based on synchronous in situ measurements at the Dunhuang site is the baseline calibration method for MERSI. To assure frequent and stable calibration updates, a multisite calibration tracking method is developed. This paper presents the FY-3B MERSI postlaunch daily calibration updating method based on multisite calibration tracking with the Dunhuang VC correction, the long-term sensor response on-orbit change, and the calibration performance evaluation. A reflectance-based method is used for the Dunhuang VC, and the reflectance calibration uncertainties are within 3% for most MERSI bands. The multisite calibration tracking method relies on simulated radiation over several stable sites without synchronous in situ measurements. A postlaunch daily calibration updating model is established using a linear function of days since launch to describe the long-term trend. The calibration updating model is validated by the Dunhuang VC, showing the relative bias within 3.5% for most bands. It is found that the shortwave channels of MERSI experience large degradation, particularly the 412-nm band with an annual degradation rate of approximately 18%, whereas most red and near-infrared bands are relatively stable. Using the calibration updating model with the Dunhuang VC correction, the recalibrated MERSI data are validated against Moderate Resolution Imaging Spectroradiometer by near synchronous-nadir-observation analysis, and good agreement is achieved. [ABSTRACT FROM PUBLISHER]

For the safe operation of nuclear power plants (NPPs), it is significant to promptly and correctly identify malfunctions/transients, which is difficult for the operators by monitoring the variation of important parameters. In this paper, a novel method is proposed for the transient identification in NPPs. It directly models the transients in a linear space that is represented by a matrix instead of a training process. Then a transient can be represented via a linear combination of the columns of the modeling matrix, and the coefficient vector encodes the identity of the transient. To obtain the coefficient vector, the smoothed \ell^0-norm optimization (SL0) algorithm is adopted, where the truncated singular value decomposition (TSVD) method is combined to improve the stability. Then the identification of a transient can be accomplished by examining the property of the solution using three quantities. The proposed method can correctly classify the transients and successfully reject “unknown” types, and it is applicable under a wide range of operational conditions. It is verified by simulator data of pebble-bed modular high temperature gas-cooled reactor nuclear power plant (HTR-PM) developed by Institute of Nuclear and New Energy Technology with Tsinghua University. [ABSTRACT FROM PUBLISHER]

With the rapid development of high-speed and high-power railway system in China, power quality such as the negative sequence current and harmonic current caused by electric locomotives becomes more and more critical. This paper proposes a half-bridge-converter-based railway static power conditioner (RPC) (HBRPC) which consists of two half-bridge converters connected by two capacitors in series. Compared with the traditional RPC, the HBRPC requires only a pair of power switch legs and two capacitors. Under the premise of accomplishing the same function of RPC, the proposed conditioner can reduce half of the power switches, which can make it with lower cost and hardware complexity. A double-loop control is proposed for HBRPC to keep the dc-link voltage stable and achieve the dynamic tracking of the current reference signals, while a balanced voltage control is proposed to eliminate the error of two capacitor voltages and maintain the normal operation of HBRPC. Finally, simulation and experiment results have verified the proposed structure and its control method effectively. [ABSTRACT FROM PUBLISHER]

This paper explores how interfirm variations in their in-licensed technology portfolios influence subsequent innovation performance. Existing studies mainly assume licensed technologies are homogeneously accessible to firms, and a prevailing explanation as to why firms vary in their innovation performance lies in differences of absorptive capacity. In this study, we intend to relax this assumption and use data about 186 Chinese indigenous firms to investigate how differences in in-licensing portfolios lead to different effects on innovation performance. We find that firms benefit from prior in-licensing technologies and the result is related to four dimensions of their licensing portfolios. We find that 1) the scale of firms’ technology in-licensing has an inverted-U relationship with their subsequent innovation performance; 2) firms that license-in foreign technologies tend to outperform those that predominantly license-in technologies from domestic sources; 3) the newness of firms’ technology in-licensing yields a positive effect on subsequent innovation performance; and 4) a diverse portfolio of licensors from whom technologies are licensed-in has an inverted-U relationship with firms’ subsequent technological diversity. [ABSTRACT FROM PUBLISHER]

A great progress in the electrical performance of high-temperature superconductor (HTS) REBCO tapes allows for a much increased transport current capability in cables especially at high magnet fields. This is of interest to future fusion magnet applications. A variant type of twisted stacked-tape cable called quasi-round twisted stacked-tapes conductor (QisTac) is proposed and developed for the superconducting conductor of the China fusion engineering test reactor. The stack of the twisted HTS tapes is wrapped by a tight spiral made with copper wires. The stack with the copper wire is, then, soldered to form the solid round conductor, which is reliable and easy to manufacture in long lengths. A QisTac sample with four REBCO tapes was prepared and measured at 77 K and in the self-field condition. The measurement result shows the expected critical current calculated from the individual tapes considering the self-field effect. The bending characteristic of the sample was also tested under different bending radii. The critical current is reduced by roughly 5% at 0.54% bending strain. Some residual bending strain is maintained when the maximal bending force is released. This result is promising, but reproducibility testing and tests at high field and current are needed for future high field application. [ABSTRACT FROM AUTHOR]

The space environment monitor (SEM), onboard the Chinese meteorological satellites FengYun-3A/B, has the abilities to measure proton flux in 3-300-MeV energy range and electron flux in 0.15-5.7-MeV energy range. SEM can also detect the heavy ion compositions, satellite surface potential, the radiation dose in sensors, and the single events. The space environment information derived from SEM can be utilized for satellite security designs, scientific studies, development of radiation belt models, and space weather monitoring and disaster warning. In this paper, the SEM's instrument characteristics are introduced, and the postlaunch calibration algorithm is presented. The applications in monitoring space weather events and the service for manned spaceflights are also demonstrated. [ABSTRACT FROM AUTHOR]

This paper attempts to address the influence of sugar as a contaminant on outdoor insulation characteristics of insulators in a substation. Strong discharge activity was occurred under relative humidity less than 80% on insulators in a 500 kV substation at south China. A preliminary viewpoint that sugar as a contaminant leads to this strong discharge was drawn by investigating pollution sources around the substation and analyzing pollution layer conditions of discharged insulators. In order to further confirming this viewpoint and proposing the appropriate solutions for avoiding this discharge activity, the outward appearance, the surface conductivity, the discharge inception voltage and the flashover voltage of glass insulator and room temperature vulcanized (RTV) coated insulator under sugary and non-sugary contamination were investigated in detail in the lab. Furthermore, the hydrophobicity and hydrophobicity transference of RTV coated insulator were also investigated. The research results show that sugary contamination is very absorbent and viscous, outdoor insulation characteristics of insulators covered with sugary contamination are worse than that covered with non-sugary contamination, but outdoor insulation characteristics of RTV coated insulator covered with sugary contamination is still better than that of non-RTV coating insulator with non-sugary contamination. So it is still a specific solution to inhibit the discharge activity of insulators in the substation by spraying RTV coating. Of course, removing the sugar canes themselves from this area is the best solution. [ABSTRACT FROM PUBLISHER]

Chinese Spallation Neutron Source (CSNS) is a facility planned to be built in China in the coming years. It is composed of 80 MeV Linac, 1.6 GeV Rapid Cycling Synchrotron (RCS) and target station. To accelerate the proton beam from 80 MeV to 1.6 GeV, the RCS requires the field of dipole and quadrupole magnets to change with sine waveform of 25 Hz plus a biased DC. For large amplitude AC magnets with large aperture, there are critical issues to be addressed, such as eddy current induced in the magnet yoke, coils and endplates, vibration of the yoke and coil, field tracking between dipoles and quadrupoles, and so on. To study these issues, one prototype dipole magnet and one prototype quadrupole magnet have been developed and tested. In this paper, the design, fabrication and tests of the two magnets will be described. [ABSTRACT FROM PUBLISHER]

The three-dimentional plant canopy architecture is often characterized using the foliage clumping index useful for ecological and land surface modeling. In this paper, an algorithm is developed to retrieve the foliage clumping index with the Moderate Resolution Imaging Spectroradiometer bidirectional reflectance distribution function (BRDF) parameter product (MCD43A1), which is generated using the RossThick-LiSparse Reciprocal (Ross-Li) model. First, the Ross-Li model is modified to improve the simulation of the reflectance at hotspot using the Polarization and Directionality of Earth Reflectance measurements as benchmarks to determine BRDF parameters. Then, the modified model (Ross-Li-H) is used to simulate the reflectance at hotspot and darkspot, which is used to calculate the normalized difference between hotspot and darkspot (NDHD). With the relationship between clumping index and NDHD simulated by the 4-Scale geometrical model, the clumping index over China's landmass at 500-m resolution is retrieved every 8 days during the period from 2003 to 2008. Finally, The effect of topography on the retrieved clumping index is corrected using a topographic compensation function calculated from the digital elevation model at 90-m resolution. The topographically corrected clumping index values correlate well with field measurements at five sites over China, indicating the feasibility of the algorithm for retrieving the clumping index from the MCD43A1 product. [ABSTRACT FROM AUTHOR]

In order to accurately and effectively diagnose the transmission line faults of the power system, a genetic-algorithm support vector machine and the D-S evidence theory based fault diagnostic model is proposed. Two genetic-algorithm support vector machine based diagnosis boxes separately identify the fault types to get two kinds of preliminary diagnostic results according to the voltage and current phasors data from the phasor measurement units. Then, a deviation coefficient is derived to represent the diagnostic conflicts existing in the two kinds of preliminary diagnostic results. The mass function of the D-S evidence theory is updated by using the deviation coefficient to eliminate the diagnostic conflicts and improve the diagnosis accuracy. Finally, the proposed diagnostic model was applied in an actual power system in Hubei province in China. The simulation results and practical results indicated the feasibility and the effectiveness of the diagnostic model. [ABSTRACT FROM AUTHOR]

A frequency-dependent network equivalent (FDNE) is essential to capture wide-band frequency dynamics in the hybrid simulation of large-scale modular multi-level converter based ac–dc grids. The FDNE model must be enforced to be passive, ensuring the numerical stability in time-domain simulations. However, existing passive enforcement techniques based on global optimization perturbations cannot guarantee convergence, accuracy, and efficiency simultaneously. To address the issues, a two-layer FDNE (T-FDNE) model is developed for the ac grids. The two layers, namely, detailed layer and equivalent layer, have their admittances derived by perturbation test and analytical approach, respectively. The passivity of the T-FDNE model is guaranteed by the proposed local passivity compensation technique using auxiliary rational functions. Since no optimization is required and the passivity is enhanced locally, the convergence, accuracy, and efficiency can be improved considerably. By incorporating the T-FDNE model into the interface model of transient (TS) and electromagnetic transient hybrid simulations, wide-band frequency interactions, especially those of very high frequency, can be reflected effectively. The performance (efficiency and accuracy) of the T-FDNE model as well as of the hybrid simulation method has been validated on a modified and practical ac–dc system in China. [ABSTRACT FROM AUTHOR]

The ARGO-YBJ experiment has been in stable data taking since November 2007 at the YangBaJing Cosmic Ray Laboratory (Tibet, China, 4300 m a.s.l.). Its main fields of research are \gamma-astronomy with an energy threshold of a few hundred GeV and cosmic ray physics in the 1\div 1000~TeV energy range. The ARGO-YBJ detector consists of a single layer of RPCs operated in streamer mode, housed in a large building of about 11\thinspace000~m^2). Signals from each RPC are picked up with 80 readout strips 61.8 cm wide and 6.75 cm long (23~strips/m^2) that allow the shower front reconstruction with a high space-time resolution. In order to fully investigate the PeV region, where the previous (digital) readout saturates, an analog one has been implemented by instrumenting each RPC with two large size electrodes of dimension 1.39 \times 1.23~m^2. The 130 Clusters of the central carpet have been instrumented with the charge readout hardware and software since November 2009. In this paper we describe the hardware solution that implements the real-time charge readout in the ARGO-YBJ experiment, paying a special attention to the synchronization with the central data acquisition system, which is also described. [ABSTRACT FROM PUBLISHER]

It is expected that superconducting technologies will play an important role in the future smart grid, because the application of superconductor technologies in the power grid can decrease power losses, relieve overload, avoid higher levels of transmission voltage, increase power transmission capacity, and improve power quality and grid stability. In recent years, high temperature (high-Tc) superconducting power technologies have achieved remarkable progress. High temperature superconducting (HTS) power equipment, such as HTS power cables, HTS transformers, high-Tc superconducting fault current limiters (SFCL), and high-Tc superconducting magnetic energy storage devices (SMES) have been demonstrated in the power grids of many countries. With the development of HTS power equipment, the construction of a HTS power substation is ready. In China, a 10.5 kV HTS power substation is under construction in Baiyin city, Gansu province. The substation integrates a HTS power cable, a HTS transformer, a HTS fault current limiter, and a high-Tc SMES. All these HTS power devices, which were previously developed by the Institute of Electrical Engineering (IEE), Chinese Academy of Sciences (CAS), have been demonstrated to operate for a long time in the commercial power grid. In this paper, the design and constructing progress of the HTS substation are introduced in detail. [ABSTRACT FROM AUTHOR]

The byproduct gas in steel industry is one of the most significant energy resources of an enterprise. Due to the large quantity of yield, fluctuation, and various categories of users encountered in a blast furnace gas (BFG) system, it is very difficult to accurately predict the amount of gas to be generated and forecast the users' consumption demand. In this paper, a two-stage online prediction method based on an improved echo state network (ESN) is proposed to realize forecasting in the BFG system. In this method, one completes the prediction realized at the levels of BFG generation and consumption using a class of ESN with input compensation and parameter optimization. At the second stage, to predict gas holder level of the BFG system, the energy flows being predicted at the first stage are denoised, and their correlation with the holder level are determined by using a concept of grey correlation with time delay. Then the effect factors exhibiting high correlation levels are extracted to construct the model of the gas holder. The prediction system designed in this manner is applied in the Energy Center of Baosteel Co., Ltd, China. The results demonstrate that the prediction system exhibits high accuracy and can provide an effective guidance for balancing and scheduling of the byproduct energy. [ABSTRACT FROM PUBLISHER]

Traditional methods used to predict the ground-wave field strength at low frequency are not applicable for terrains with serious irregularities because of the analytical approximations. In this paper, the two dimensional finite-difference time-domain (FDTD) algorithm is applied to calculate the field strength of the low frequency (LF) ground wave propagating over irregular terrains. The propagation characteristics are studied as functions of the mountain's gradient, height, and width, respectively. We also focus on studying the cases with multiple mountains in the path. Moreover, the error of the traditional integral equation method is analyzed by comparisons. The results show that when the mountain's gradient and height are high, additional oscillations in the field strength will appear in front of and in the mountain region due to the wave reflection and scattering. At last, measurements of the Loran-C signals are taken along a real path between Pucheng and Tongchuan in Shaanxi province, China. It is found that most of the measured and FDTD results have good agreements while some still have big errors owing to the model approximation. The FDTD method gets better precision than the integral equation method in the irregular terrain. [ABSTRACT FROM AUTHOR]

The Shangdu power plant has four 600-MW turbine-generators connected to the North-China Grid through two 500-kV transmissions, which are compensated with 45% fixed series capacitors. Extensive studies conducted on the system model indicate that the system suffers from multimodal subsynchronous resonance (SSR). To solve the problem, a countermeasure is developed by combining the supplementary excitation damping control (SEDC) and the torsional stress relay (TSR). In this paper, the characteristics of the SSR problem are investigated. Then the developed SEDC is presented. To validate the effectiveness of the proposed SEDC as well as the results of model studies, field tests were conducted under various operating conditions. The tests fully exposed the realistic threat of SSR in the system. Meanwhile, it is demonstrated that the developed SEDC can improve torsional damping significantly, and thus solve the multimodal SSR problem effectively. This is the first time in China that practical SEDCs have been developed and their ability to mitigate multimodal SSR has been verified in a real series-compensated system. [ABSTRACT FROM AUTHOR]

Automatic dialect classification has emerged as an important area in the speech research field. Effective dialect classification is useful in developing robust speech systems, such as speech recognition and speaker identification. In this paper, two novel algorithms are proposed to improve dialect classification for text-independent spontaneous speech in Arabic and Spanish languages, along with probe results for Chinese. The problem considers the case where no transcripts but dialect labels are available for training and test data, and speakers are speaking spontaneously, which is defined as text-independent dialect classification. The Gaussian mixture model (GMM) is used as the baseline system for text-independent dialect classification. The major motivation is to suppress confused/distractive regions from the dialect language space and emphasize discriminative/sensitive information of the available dialects. In the training phase, a symmetric version of the Kullback–Leibler divergence is used to find the most discriminative GMM mixtures (KLD-GMM), where the confused acoustic GMM region is suppressed. For testing, the more discriminative frames are detected and used via the location of where the frames are in the GMM mixture feature space, which is termed frame selection decoding (FSD-GMM). The first KLD-GMM and second FSD-GMM techniques, are shown to improve dialect classification performance for three-way dialect tasks. The two algorithms and their combination are evaluated on dialects of Arabic and Spanish corpora. Measurable improvement is achieved in both two cases, over a generalized maximum-likelihood estimation GMM baseline (MLE-GMM). [ABSTRACT FROM PUBLISHER]

Many applications using accelerator beams require a nearly uniform beam distribution at the target. A nested structure magnet producing a step-like magnet field has been proposed to transform an originally Gaussian or even irregular distribution into a more-or-less uniform one at targets. In this paper, the prototyping of a step-like field magnet is presented, which is based on the application in the China Spallation Neutron Source where the magnets are used to obtain a uniform beam profile from an initially irregular distribution at the spallation target. It includes the magnet design, 3D magnetic field calculation, prototype fabrication and field measurement. The prototyping confirms the technical feasibility of the magnet structure and the magnetic field quality consistent with the field calculations. The design improvements are discussed from the prototyping experience. [ABSTRACT FROM AUTHOR]

The High Magnetic Field Laboratory, Chinese Academy of Sciences is developing a 40 T hybrid magnet. The hybrid magnet cryostat consists of two separate but attached cryostats. The main function of the cryostats is to provide a thermal barrier between the ambient temperature experimental hall and the supercritical helium forced cooled superconducting magnet. It also provides feed-through penetrations for all the connecting elements inside and outside the cryostat. The Outsert Magnet Cryostat is a large vacuum vessel with cylindrical shell, standard elliptical top, and flat bottom. The structural analyses, including buckling, for the cryostat vessel have been carried out using finite element code. Stress analysis results show that the maximum Von Mises stress will be below the allowable value. In this paper, we focus on the structural analyses and design of the cryostat. [ABSTRACT FROM AUTHOR]

Coils for pulsed magnets in the range of 50-75 T are developed with optimized combinations of conductors and reinforcement for the prototype laboratory of the Wuhan High Magnetic Field Center (WHMFC). The basic design tool is a Pulsed Magnet Design Software package (PMDS) for calculating the capacitor discharge, conductor heating, mechanical stresses and the residual stress, including plastic deformation and winding tension. A 1 MJ capacitor bank is equipped with a thyristor switch, a mechanical switch, polarity reversal switches, a current limiting inductor and a diode crowbar. The design and the test results of the magnets, of the protection inductance and of the capacitor bank are presented and discussed in this paper. [ABSTRACT FROM AUTHOR]

A25 kV/40 kA protection inductor with low stray field was designed and the first prototype was fabricated. The protection inductor protected the thyristor switch in the capacitor bank, limit the current at 40 kA in case of a short circuit. It was designed as a toroidal system consisting of 12 coils evenly distributed in the perimeter of a circle. The inductance could be changed easily by adjusting the number of coils. The structure of coils was optimized to withstand the great electromagnetic force produced by the 40 kA current. The coils were wound by a 4 ∗ 45 mm copper strip standing on edge. Each coil was externally reinforced by a stainless steel ring tightly enclosing the coil. The first prototype was fabricated. Its inductance and magnetic field were tested. The prototype has been mounted in the 1 MJ module and is now in operation. In this paper, the structure design, fabrication and testing of a new protection inductor are presented. The testing results are discussed. Tested inductance was 1.05 mH and direct resistance was 16 MΩ. The first prototype was proved to be successful and 13 more protection inductors will be made after some improvements. [ABSTRACT FROM AUTHOR]

A 40 T hybrid magnet system will be built at the Chinese High Magnet Field Laboratory (CHMFL), Chinese Academy of Sciences. It will include a 29 T resistive insert with a clear bore of 32 mm and a 11 T superconducting outsert with a room temperature bore of 580 mm. The superconducting outsert, which will be wound with cable-in-conduit conductors (CICC), is graded in function of the magnetic field. The high field section of the superconducting outsert will use Nb3Sn superconductors and the low field section will be made of NbTi superconductors. At present, the preliminary design of the superconducting outsert has almost been completed. This paper describes features, such as conductor design, coil winding, heat treatment, support structure design, mechanical stress analysis. [ABSTRACT FROM AUTHOR]

The Shanghai Synchrotron Radiation Facility (SSRF) is a third-generation light source with major emphasis on insertion device (ID) sources. In the storage ring there are 20 straight sections, each about six or ten meters in length, for possible insertion devices. Currently there installed three undulators and two wiggler installed in five straight sections [1]-[3]. They were originally designed and fabricated by the Shanghai Institute of Applied Physics (SINAP). A variable polarizing undulator was constructed as the light source of the soft X-rays beamline for SSRF. This local control system consists of a Siemens PLC and a six axis Masterdrive motion controller. Four servo motors control the gap--two on the upper girder and two on the lower girder, and another two servos controls the phase--one on the upper girder outer and one on the lower girder inner. The main control system at the SSRF is experimental physics and industrial control system (EPICS). This paper will discuss in detail the design philosophy and the implementation of the Six-motor insertion device control system. This control system has been in operation for about one year. [ABSTRACT FROM AUTHOR]

A successful public-private partnership (PPP) scheme can be described as one that can lead to the delivery of high-quality end products and/or services, which can satisfy the needs of the community, achieve the intended targets/goals of the government, as well as provide a favorable financial return for the private sector involved with the project. This study aims to establish an evaluation framework for the initial feasibility evaluation of a PPP project that would satisfy all the stakeholders. The factors for evaluating the feasibility of PPP projects can be classified into five broad categories: technical; financial and economic; social; political and legal; and others. Through the structural equation modeling approach, data attained from a questionnaire survey conducted in Hong Kong was analyzed and a model was developed to examine the relationships between different evaluation factors and the overall satisfaction of stakeholders. The results indicate that technical and social aspects are critical to the feasibility of PPP projects, and therefore, are the determining factors for success. This paper should assist relevant stakeholders to improve their understanding on the relative importance of the evaluation factors, and help to establish a comprehensive framework for decision makers to evaluate the feasibility of PPP projects. The predictors for PPP project success were also determined to enrich the knowledge base and help formulate management strategies to better implement the PPP project delivery approach. [ABSTRACT FROM AUTHOR]

High blood pressure (BP, hypertension) is a leading chronic condition in China and has become the main risk factor for many high-risk diseases, such as heart attacks. However, the platform for chronic disease measurement and management is still lacking, especially for underserved Chinese. To achieve the early diagnosis of hypertension, one BP monitoring system has been designed. The proposed design consists of three main parts: user domain, server domain, and channel domain. All three units and their materialization, validation tests on reliability, and usability are described in this paper, and the conclusion is that the current design concept is feasible and the system can be developed toward sufficient reliability and affordability with further optimization. This idea might also be extended into one platform for other physiological signals, such as blood sugar and ECG. [ABSTRACT FROM AUTHOR]

Setting in China's emerging economy, this study examines the underlyingworkingmechanisms through which acquisitive learning and experimental learning produce positive impacts on indigenous innovation. We theorize that behavior control and output control will have different moderating effects on the learning and indigenous innovation relationships. Empirical analyses of a survey dataset of 607 Chinese firms provide supporting evidence to the theoretical model advanced in this study. Experimental learning mediates the relationship between acquisitive learning and indigenous innovation. Behavior control negatively moderates the relationship between acquisitive learning and indigenous innovation, while positively moderates the relationship between experimental learning and indigenous innovation. The moderating effects of output control on the relationships between both types of learning and indigenous innovation are significant and inverse-Ushaped. The paper concludes with a discussion of the relevant theoretical contributions and practical implications stemming from these findings, study limitations, and potential future research directions. [ABSTRACT FROM AUTHOR]

This paper examines how multinational corporations (MNCs) protect their intellectual property (IP) when they conduct R&D in countries with weak IP rights (IPRs) protection. Findings from a small-scale survey and three case studies in China show that hierarchical segmentation of the R&D process can provide an effective way for IPR protection. Furthermore, a modular R&D structure adopted by many information technology companies can facilitate the hierarchical segmentation. Because R&D is becoming distributed across locations with varying levels of IPR protection, a center-peripheral R&D organizational structure is emerging within MNCs as R&D globalization proceeds. [ABSTRACT FROM AUTHOR]