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30 June 2016, Volume 21 Issue 3 Previous Issue    Next Issue

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Research on Maximum Power Point Tracking in Redundant Load Mode for Photovoltaic System WANG Jianjun1* (王建军), CHEN Shanben2 (陈善本), SHAO Yufeng1 (邵宇丰) 2016, 21 (3):  257-262.  doi: 10.1007/s12204-016-1720-5 Abstract ( 750 )   In order to ensure that the photovoltaic (PV) array always works at the global maximum point of power to increase the system’s overall efficiency, this paper leads the study on maximum power point tracking (MPPT) in redundant load mode. A new control system is designed by combining the redundant electronic load module, embedded controller, supportive capacitor and boost circuit. The system adjusts duty ratio of boost circuit dynamically based on the maximum power point parameter provided by redundant load unit in order to realize MPPT. An experiment shows that no matter whether system is under an even illumination or partly perturbed by shadow, this method can find the exact maximum power point. References | Related Articles | Metrics

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On-Line Adaptive Repetitive Controller for Power Factor Correction Systems JU Jialing (鞠嘉凌), LIU Bin*(刘 斌), LI Jun (李 俊),HU Zhiliang (胡质良), WAN Haiyan (万海燕) 2016, 21 (3):  263-269.  doi: 10.1007/s12204-016-1721-4 Abstract ( 633 )   When the fundamental frequency is shifting, it is hard for traditional repetitive controller to work at the resonant frequencies. In this paper, a novel adaptive repetitive controller for power factor correction systems is proposed to suppress the current harmonics. Through the controller, the shifting sampling times of the repetitive controller in a fundamental period can be obtained. Mathematical analysis, simulations and physical experiments have validated the effectiveness of the adaptive repetitive controller. References | Related Articles | Metrics

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Effects of Compressibility and Knudsen Number on the Aero Optics in Hypersonic Flow Fields REN Wei (任 维), LIU Hong* (刘 洪) 2016, 21 (3):  270-279.  doi: 10.1007/s12204-016-1722-3 Abstract ( 612 )   Tsien summarized the similarity in hypersonic flows, and related Knudsen number to Mach number and Reynolds number. Recently, a path-based problem, aero-optical effect, arises in hypersonic flows, and it concerns about the compressibility and the Knudsen number of the gas flows, which differs from the Tsien’s focus to some extent. In this paper, the similarity of hypersonic aero optics is theoretically studied, and both flow fields and induced aero-optical effect after flows pass through a cylinder are predicted by a well-accepted particle-based method, direct simulation Monte-Carlo (DSMC) method. The results show that the optical distortions are inversely proportional to the Knudsen number, while the compressibility plays an important role in the optical degradations. Hence, it is confirmed that the effects of Mach number and Knudsen number on the aero-optical effect induced by hypersonic flows are of great significance. Besides, since the Knudsen number is defined straightforwardly based on the optically active region, the physics is clearer than any other similarity criteria. References | Related Articles | Metrics

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Exploiting Parallelism in the Simulation of General Purpose Graphics Processing Unit Program ZHAO Xia* (赵 夏), MA Sheng (马 胜), CHEN Wei (陈 微), WANG Zhiying (王志英) 2016, 21 (3):  280-288.  doi: 10.1007/s12204-016-1723-2 Abstract ( 609 )   The simulation is an important means of performance evaluation of the computer architecture. Nowadays, the serial simulation of general purpose graphics processing unit (GPGPU) architecture is the main bottleneck for the simulation speed. To address this issue, we propose the intra-kernel parallelization on a multicore processor and the inter-kernel parallelization on a multiple-machine platform. We apply these two methods to the GPGPU-sim simulator. The intra-kernel parallelization method firstly parallelizes the serial simulation of multiple compute units in one cycle. Then it parallelizes the timing and functional simulation to reduce the performance loss caused by the synchronization between different compute units. The inter-kernel parallelization method divides multiple kernels of a CUDA program into several groups and distributes these groups across multiple simulation hosts to perform the simulation. Experimental results show that the intra-kernel parallelization method achieves a speed-up of up to 12 with a maximum error rate of 0.009 4% on a 32-core machine, and the inter-kernel parallelization method can accelerate the simulation by a factor of up to 3.9 with a maximum error rate of 0.11% on four simulation hosts. The orthogonality between these two methods allows us to combine them together on multiple multi-core hosts to get further performance improvements. References | Related Articles | Metrics

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Saliency Motivated Pulse Coupled Neural Network for Underwater Laser Image Segmentation WANG Bo* (王 博), WAN Lei (万 磊), LI Ye (李 晔) 2016, 21 (3):  289-296.  doi: 10.1007/s12204-016-1724-1 Abstract ( 609 )   The detection range of underwater laser imaging technology achieves 4—6 times of detection range of conventional camera in intervening water medium, which makes it very promising in oceanic research, deep sea exploration and robotic works. However, the special features in underwater laser images, such as speckle noise and non-uniform illumination, bring great difficulty for image segmentation. In this paper, a novel saliency motivated pulse coupled neural network (SM-PCNN) is proposed for underwater laser image segmentation. The pixel saliency is used as external stimulus of neurons. For improvement of convergence speed to optimal segmentation, a gradient descent method based on maximum two-dimensional Renyi entropy criterion is utilized to determine the dynamic threshold. On the basis of region contrast in each iteration step, the real object regions are effectively distinguished, and the robustness against speckle noise and non-uniform illumination is improved by region selection. The proposed method is compared with four other state-of-the-art methods which are watershed, fuzzy C-means, meanshift and normalized cut methods. Experimental results demonstrate the superiority of our proposed method to allow more accurate segmentation and higher robustness. References | Related Articles | Metrics

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A Novel De-noising Method Based on Discrete Cosine Transform and Its Application in the Fault Feature Extraction of Hydraulic Pump WANG Yukui1,2* (王余奎), HUANG Zhijie1 (黄之杰), ZHAO Xucheng1 (赵徐成), ZHU Yi1 (朱 毅), WEI Dongtao1 (魏东涛) 2016, 21 (3):  297-306.  doi: 10.1007/s12204-016-1725-0 Abstract ( 571 )   Aiming at the existing problems of discrete cosine transform (DCT) de-noising method, we introduce the idea of wavelet neighboring coefficients (WNC) de-noising method, and propose the cosine neighboring coefficients (CNC) de-noising method. Based on DCT, a novel method for the fault feature extraction of hydraulic pump is analyzed. The vibration signal of pump is de-noised with CNC de-noising method, and the fault feature is extracted by performing Hilbert-Huang transform (HHT) to the output signal. The analysis results of the simulation signal and the actual one demonstrate that the proposed CNC de-noising method and the fault feature extraction method have more superior ability than the traditional ones. References | Related Articles | Metrics

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Deliberative Collision Avoidance for Unmanned Surface Vehicle Based on the Directional Weight WU Gongxing* (吴恭兴), SHI Danda (史丹达), GUO Jiamin (郭佳民) 2016, 21 (3):  307-312.  doi: 10.1007/s12204-016-1726-z Abstract ( 599 )   The purpose of this study is to realize the intelligent deliberative obstacle avoidance for unmanned surface vehicle (USV), based on the International Regulations for Preventing Collisions at Sea called COLREGS. Firstly, a three-level system architecture is designed for the ship intelligent collision avoidance system. Secondly, an intelligent collision avoidance algorithm is presented based on the calculation of motion parameters and the rules of COLREGS. Thirdly, according to COLREGS, the marine environment is modeled from the electronic chart data and radar information, and a deliberative collision avoidance algorithm is written. Finally, the deliberative collision avoidance simulation is carried out for the USV. The feasibility and reliability of intelligent collision avoidance algorithm are verified by the vivid simulation results. References | Related Articles | Metrics

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Buckling Design of Conical Shells Based on Palm Trunks: Survey of Power-Law Distributed Thin-Walled Conical WU Lei1 (吴 磊), LIU Wangyu2* (刘旺玉), SU Zhangming2 (苏章明),WANG Ningling2 (汪宁陵), HUANG Jiale2 (黄家乐) 2016, 21 (3):  313-319.  doi: 10.1007/s12204-016-1727-y Abstract ( 644 )   This paper aims at the elastic buckling of multilayered thin-walled conical shells with power-law distributed material properties under the axial load and lateral pressure based on the experimental study of palm trunks. The material properties of the shells are assumed to vary continuously in the radial direction. Relations and analytical approaches for linear buckling response are presented by using the layer-wise shell theory. The buckling behaviors of the conical shells subjected to axial and transverse loads are investigated. Parametric study in geometry (relative thickness, relative stiffness and cone angle) is performed to enhance the overall buckling resistance and minimize the weight. Numerical results show the possibility to achieve larger load-carrying capacity by simultaneously optimizing the material and geometric parameters based on the structure of palm trunks. References | Related Articles | Metrics

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A Stochastic Concession Model for Infrastructure Projects Under Build-Operate-Transfer Schemes ZHU Yinghua (朱莹华), XU Feng* (徐 峰), HU Hao (胡 昊) 2016, 21 (3):  320-327.  doi: 10.1007/s12204-016-1728-x Abstract ( 594 )   Concession period is a key factor in the arrangement of a build-operate-transfer (BOT) contract. This paper proposes a stochastic concession period model for infrastructure projects under a BOT scheme, which takes into account the impact of risks and the risk attitudes of the private investor and the government. A hypothetical case is simulated by using the Monte Carlo simulation method to illustrate the proposed model. The results indicate that even for a project with the same estimations, the concession interval can be different and depends a lot on the risk attitudes of the private investor and the government. The proposed model provides a more reasonable concession interval based on which a specific concession period can be obtained through negotiation between the two parties. References | Related Articles | Metrics

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Do China Mainland and SARs Constitute an Optimal Currency Area? Evidence from Nonlinearity and Stationarity Behavior Testing on Real Exchange Rates ZHENG Xiaoya1*(郑晓亚), YOU Haibo2 (尤海波) 2016, 21 (3):  328-334.  doi: 10.1007/s12204-016-1729-9 Abstract ( 522 )   In this article, we use the unrestricted two-regime autoregressive threshold model to test both nonlinearity and stationarity of China’s real exchange rate against its Hong Kong and Macau special administrative regions (SARs). Our main finding is that China’s real exchange rate is neither linear nor stationary, indicating that the purchasing power parity does not hold between China Mainland and its two SARs, which implies, to certain extent, the three economies may not meet the condition of constituting an optimal currency area. References | Related Articles | Metrics

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A Dynamic Computable General Equilibrium Simulation of China’s Innovation-Based Economy Under the New Normal LI Chengyu (李程宇), SHAO Shuai* (邵 帅) 2016, 21 (3):  335-342.  doi: 10.1007/s12204-016-1730-3 Abstract ( 504 )   Researching China’s innovative economic and financial innovation issues under the background of the New Normal, we need to carefully analyze the internal structure and interaction of China’s macroeconomics. The computable general equilibrium (CGE) model has outstanding advantages on predicting the external shock influences on economic system, but previous studies on forecast for China’s future economy mostly considered a high growth rate which is hard to comply with the New Normal scene. By constructing China’s macroeconomic dynamic CGE (DCGE) model and anticipating the economic impact of the New Normal, this paper finds that the New Normal has a certain extent inhibition on China’s macro-economy and innovation. However, after adding the research and development (R&D) subsidy policy, the negative impacts of the New Normal on macro-economy can be eliminated to realize the optimization of economic structure. In addition, after combining the financial innovation promoting policy and the KeQiang index through the simulation of macro-economy, we find that the quality of economic growth is improved. Finally, we provide the policy recommendations for the realization of an innovative economy under China’s New Normal. References | Related Articles | Metrics

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Different Types of Monetary Policy Instruments and Regional Housing Prices: A Comparative Study on the Influences of Regulation in China YANG Gang1,2* (杨 刚), WANG Hongwei2 (王洪卫), WANG Zhengzheng2 (王诤诤) 2016, 21 (3):  343-349.  doi: 10.1007/s12204-016-1731-2 Abstract ( 542 )   Using system clustering method to group China’s provinces into 3 new groups according to their housing prices, then establishing a state-space model and applying the Kalman filter calculation, we made a comparative analysis of the influences of different types of monetary policy instruments towards different regional housing prices. The empirical results show that both the quantitative instruments represented by M2 and the pricing instruments represented by real interest rate have increasing influences on different regional housing prices, but the former influence is much stronger than the latter. The influential differences of quantitative instruments to regional housing prices are much greater. It means the higher the regional housing price is, the greater the influence is. Therefore, the central bank shall optimize the combination of monetary policy instruments according to the above characteristics of different types of monetary policy instruments in order to acquire the regulatory target of real estate market. References | Related Articles | Metrics

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Study on International Development of Financial Asset Securitization:An Example of Mining Rights XUE Yaozu (薛曜祖) 2016, 21 (3):  350-354.  doi: 10.1007/s12204-016-1732-1 Abstract ( 487 )   Mining right asset securitization is a market financing pattern for mineral resources, and it is a creative application of financial asset securitization. Nowadays, because of world energy price decline, the world energy market is facing weak investment and financing sharply under pressure. Under this background, this paper aims at briefly commenting on the content, processes and impact of mining right asset securitization, understanding the international mining right asset securitization specific practices, and then combining the situation of China (Shanghai) Pilot Free Trade Zone so as to give advice for the development of mining right asset securitization in China. For instance, mineral mining rights and expenses system design are not clear, so the mineral values do not reflect their true costs and the need to speed up market credit system construction. References | Related Articles | Metrics

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Small and Medium-Sized Enterprises Closed-Loop Supply Chain Finance Risk Based on Evolutionary Game Theory and System Dynamics ZHANG Cheng (张 诚) 2016, 21 (3):  355-364.  doi: 10.1007/s12204-016-1733-0 Abstract ( 540 )   After building a dynamic evolutionary game model, the essay studies the stability of the equilibrium in the game between the commercial banks and the closed-loop supply chain (CLSC) enterprises. By design of systematic mechanism based on system dynamics theory, capital chains of independent small and medium-sized enterprises (SMEs) on CLSC are organically linked together. Moreover, a comparative simulation is studied for the previous independent and post-design dependent systems. The study shows that with business expanding and market risk growing, the independent finance chains of SMEs on CLSC often take on a certain vulnerability, while the SMEs closed-loop supply chain finance system itself is with a strong rigidity and concerto. References | Related Articles | Metrics

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Research on Gray System and Quantitative Model About the Fund-Raising Ability to China Private Equity Fund MENG Meng1 (蒙 蒙), YU Jiuhong1,2* (禹久泓) 2016, 21 (3):  365-369.  doi: 10.1007/s12204-016-1734-z Abstract ( 474 )   It is a rather challenging project to seek the amount of funds raised by funds-raising companies. This paper is focused on China private equity funds that have succeeded in raising their funds. The grey systemic model is applied in the research and a formula is established for the law of fund-raising of the private equity funds in order to sum up the capacity of China private equity investment funds and to establish a model accordingly. References | Related Articles | Metrics

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The Coordination Mechanism of Supply Chain Finance Based on Tripartite Game Theory ZHAO Jinshi1,2* (赵金实), DUAN Yongrui3 (段永瑞) 2016, 21 (3):  370-373.  doi: 10.1007/s12204-016-1735-y Abstract ( 650 )   Supply chain finance (SCF) is concerned because of its service efficiency for the real economy. Beside the bank, some enterprises have provided the SCF service. E-commerce platform firms develop small and micro loan system in China. A given small enterprise can apply for a loan through its platform. Based on the latest SCF developments and the relevant literature, this study focuses on the coordination mechanism of SCF. We construct a game theory model including supplier, retailer and financial service provider to analyze the decision making of them. We find the optimal solution to the supplier, retailer and financial service provider. References | Related Articles | Metrics

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Causality of Future and Spot Grain Prices Between China and the US: Evidence from Soybean and Corn Markets Against the Surging Import Pressure CAO Zhengwei1* (曹正伟), GU Haiying1 (顾海英), ZHOU Weimin1 (周伟民), YAN Shuqin2 (阎淑琴),ITO Shoichi2 (伊东正一), ISODA Hiroshi2 (磯田宏) 2016, 21 (3):  374-384.  doi: 10.1007/s12204-016-1736-x Abstract ( 515 )   As the boom of the world grain market phases out, the challenge for Chinese government has gradually moved from retarding grain exports to restraining imports. This study tries to examine the causalities of soybean and corn price movement among the United States (US) future market, Chinese domestic future market and Chinese spot markets. We find that the daily prices of all these three types of grains belong to I(1) series, and there are long-run integrations. Also Chinese soybean future prices adjust more quickly than its spot prices, while Chinese corn future prices adjust slower. This paper finds that the soybean price movement originates from the US future market, then passes through Chinese future market, and finally reaches Chinese spot market, while the corn price movement starts in Chinese spot market, then spreads to the future markets in both China and the US. Finally, this paper also provides some policy implications on how to release the pressure from the grain imports. References | Related Articles | Metrics