bluuebunny/crossref_metadata_2025 huggingface dataset:
Adaptive non‐singular fault‐tolerant control for hypersonic vehicle with unexpected centroid shift
Authors: Meng Yizhen , Jiang Bin , Qi Ruiyun
Published: June 2019

A study on hypersonic vehicle (HSV) with centroid shift and actuator fault is made to investigate the adaptive fault‐tolerant control for stability recovery of HSV operating in off‐nominal conditions. Based on the modelling and analyzing the influence of centroid shift and actuator fault on HSV, the centroid shift can cause system uncertainty, variation of inertial matrix, eccentric moment and strong coupling between the longitudinal and lateral motions, resulting in the high demand for controller. According to the difference of response time, the attitude system of HSV is divided into slow and fast loop. For handling the effect of centroid shift, actuator fault and external disturbance, an improved sliding mode controller combined with adaptive estimator is designed for the slow‐loop. Nonlinear general predictive controller (NGPC) assisted by adaptive radial basis function neural network (RBFNN) is developed for fast‐loop. In addition, the nonsingular improvements to fast‐loop controller are also made to cope with such the problem caused by the estimation of inertial matrix. The stability and tracking ability of the system are analyzed by the Lyapunov theorem of stability. At last, the simulation results show that the fault‐tolerant control algorithm provided in this paper is very effective.
Disturbance observer‐based integral fuzzy sliding‐mode control and its application to wind turbine system
Authors: Hwang Sounghwan , Park Jin Bae , Joo Young Hoon
Published: June 2019

In this study, a disturbance observer‐based integral fuzzy sliding‐mode control methodology for a wind turbine system with a non‐linear permanent magnet synchronous generator (PMSG) is proposed using the Takagi–Sugeno fuzzy model. To reduce the hardware cost of the fuzzy controller membership function, an imperfect premise matching condition is considered. Considering the matched disturbance, and an external disturbance acting on the system, a novel integral fuzzy sliding surface is proposed based on a fuzzy disturbance observer (FDOB). Therefore, various forms of external disturbances can be estimated using the FDOB. In addition, a sufficient condition for guaranteeing the asymptotic stability of the sliding motion with performance is proposed using a Lyapunov function and derived using a linear matrix inequality format. Furthermore, a reachability problem of the system states over the proposed sliding surface is derived through an appropriate Lyapunov function. Finally, the simulations for a wind turbine system using a PMSG are implemented to verify the effectiveness of the proposed method as compared with previous studies.
filtering for discrete‐time 2D T–S fuzzy systems with finite frequency disturbances
Authors: Duan Zhaoxia , Shen Jian , Ghous Imran , Fu Jinna
Published: June 2019

This study investigates the filter design problem for two‐dimensional (2D) discrete‐time non‐linear systems in Takagi–Sugeno (T–S) fuzzy model. The frequency of the exogenous disturbances is assumed to belong to a known finite frequency (FF) domain. An FF performance is defined for 2D discrete‐time systems, which generalises the standard one and makes use of the frequency‐domain characteristics of practical signals. By virtue of the defined FF performance, sufficient conditions are proposed for analysing the disturbance attenuation performance of the filtering error system. Efficient conditions are obtained to guarantee the existence of a filter and such that the error system is asymptotically stable with an FF performance index. A systematic filter design scheme is developed by converting the corresponding fuzzy filter design into a convex optimisation problem. Finally, a gas absorption system is employed to illustrate the validity of the proposed methods.
Sliding mode control for uncertain discrete‐time systems based on fractional order reaching law
Authors: Ma Haifeng , Liu Chao , Liu Yang , Xiong Zhenhua
Published: June 2019

The design and validation of a new fractional order (FO) reaching law for uncertain discrete‐time systems is studied. A sliding mode controller is subsequently constructed by adopting this law. Unlike previous works, the presented reaching law is established on the basis of the Grünwald–Letnikow FO calculus of the switching function. A high‐order disturbance compensator is integrated into this reaching law to evaluate and compensate the disturbance. A rigorous theoretical analysis is given to demonstrate the superior performance of the reaching law. Results indicate that the developed method owns the ability to guarantee an O (Tn+1) order ultimate magnitude of the quasi‐sliding mode domain. Therefore, the presented method is capable of further mitigating chattering and guaranteeing a further improvement on the control accuracy in comparison with previous reaching law methods. Moreover, sliding mode dynamics of the discrete‐time system in and out the vicinities of the sliding surface is analysed in detail. Simulation results are presented to verify the feasibility and effectiveness of the developed method.
Robust backstepping‐based trajectory tracking control for quadrotors with time delays
Authors: Liu Hao , Zhao Wanbing , Hong Sheng , Lewis Frank L. , Yu Yao
Published: June 2019

In this brief, the robust trajectory tracking control problem is addressed for uncertain quadrotor systems with time delays. The quadrotor dynamical model is an under‐actuated system subject to non‐linearity, unmodelled uncertainties, parametric perturbations, external disturbances, and state and input time delays. A robust cascade trajectory tracking controller is developed by the backstepping method and the robust compensation theory. Theoretical analysis is given to prove that the tracking errors can converge into the given neighbourhood of the origin ultimately. An on‐line unidirectional tuning method is given to determine the controller parameters. Experimental results are provided to verify the effectiveness of the proposed control approach and the parameter tuning method.
Simple saturated relay non‐linear PD control for uncertain motion systems with friction and actuator constraint
Authors: Zheng Chunhong , Su Yuxin , Mercorelli Paolo
Published: June 2019

This study addresses the problem of robust fast and high‐precision positioning of uncertain one‐degree‐of‐freedom mechanical systems with friction and actuator constraint. The proposed control is constructed within the framework of saturated proportional–derivative (PD) plus relay action. Global asymptotic positioning stability is proven by Lyapunov's direct method with Barbalat's lemma. The appealing features of the proposed control are that it is fairly easy to construct with simple intuitive structure and the absence of modelling parameter in the control law formulation, and thus it is ready to implement for practical applications. An additive feature is that the proposed control embeds the PD action within one saturation function and hence it omits the elaborating embedment of the control gains within the requested constraint. Another feature is that the proposed approach can be explicitly upper bounded a priori and thus, it has the ability to protect the actuator from saturation completely and to ensure global asymptotic stability featuring fast transient and high steady‐state positioning. Numerical simulations and real experimental results demonstrate the effectiveness and improved performance of the proposed approach.
Small‐gain theorem and finite‐frequency analysis of TCP/AQM system with time varying delay
Authors: Sadek Belamfedel Alaoui , Houssaine Tissir El , Noreddine Chaibi
Published: June 2019

In this study, for the first time, a stabilisation criterion is derived for the TCP/AQM system with time‐varying delay and finite‐frequency (FF) specifications. Two important results are established. The first one shows that the TCP/AQM system operates on a frequency domain. The second one introduces a new model transformation of linear systems with time‐varying delay. The objective is to alleviate the impact that buffering has on latency‐sensitive traffic while preserving bulk throughput performance. Standing on the new model transformation, the scaled small‐gain theorem and the theory, the authors suggest new conditions expressed in terms of linear matrix inequalities for designing powerful Active Queue Management. Finally, the engineering relevance of the theory has been evaluated with different realistic scenarios in NS3 and shows that FFAQM scheme provides the best quality of service.
Detection‐based weighted LFC for multi‐area power systems under DoS attacks
Authors: Cheng Zihao , Yue Dong , Hu Songlin , Xie Xiangpeng , Huang Chongxin
Published: June 2019

This study is concerned with resilient load frequency control (LFC) scheme design of multi‐area power systems with communication delay and aperiodic denial‐of‐service (DoS) attacks. First, to identify DoS attacks, a detection mechanism in the actuator side is proposed which is a time counter measuring the input delay. The identified DoS attacks are constrained by its upper bound of frequency and duration. When DoS attacks are identified, actuator switches to zero‐input strategy from hold‐input strategy. According to the switching control inputs, switched time delay system model is established to describe the attack influence on LFC system. Further, a criterion of preserving weighted performance is derived by combining piecewise Lyapunov–Krasovskii functional method with switched system method. Based on the criterion, the resilient control gain is designed by solving a set of LMIs. Finally, numerical simulations are given to verify the validness of the attack detection based resilient LFC scheme.
Impact of nonconvergence and various approximations of the partition function on the molecular column densities in the interstellar medium
Authors: Carvajal M. , Favre C. , Kleiner I. , Ceccarelli C. , Bergin E. A. , Fedele D.
Published: June 2019

We emphasize that the completeness of the partition function, that is, the use of a converged partition function at the typical temperature range of the survey, is very important to decrease the uncertainty on this quantity and thus to derive reliable interstellar molecular densities. In that context, we show how the use of different approximations for the rovibrational partition function together with some interpolation and/or extrapolation procedures may affect the estimate of the interstellar molecular column density. For that purpose, we apply the partition function calculations to astronomical observations performed with the IRAM-30 m telescope towards the NGC 7538–IRS1 source of two N-bearing molecules: isocyanic acid (HNCO, a quasilinear molecule) and methyl cyanide (CH3CN, a symmetric top molecule). The case of methyl formate (HCOOCH3), which is an asymmetric top O-bearing molecule containing an internal rotor is also discussed. Our analysis shows that the use of different partition function approximations leads to relative differences in the resulting column densities in the range 9–43%. Thus, we expect this work to be relevant for surveys of sources with temperatures higher than 300 K and to observations in the infrared.
Effects of alloying elements on mechanical and thermal characteristics of Al-6wt-%Si-0.4wt-%Mg–(Cu) foundry alloys
Authors: Choi Se-Weon , Kim Yu-Mi , Kim Young-Chan , Kang Chang-Seog
Published: June 2019

The objective of this study was to investigate the effects of alloying elements on mechanical and thermal characteristic of Al-6wt-%Si-0.4wt-%Mg–(Cu) foundry alloys after heat treatment using a universal testing machine and a laser flash apparatus. Solid solution treatment of samples was carried out at 535°C for 6 h before quenching samples in warm water. Artificial ageing treatment was conducted at various temperatures ranging from 180 to 220°C for 5 h. When Cu was added to increase the mechanical strength of Al-6wt-%Si-0.4wt-%Mg alloy, its thermal conductivity decreased. After adding 0.1wt-%Ti to an Al-6 wt-%Si-0.4wt-%Mg-0.9wt-%Cu alloy, ultimate tensile strength (UTS) was improved 18 MPa compared to that of Ti-free alloy at ageing temperature of 180°C. The addition of Ti facilitated the formation of θ′-Al2Cu and Q′-phase, which resulted in increased UTS at room temperature. In the case of Cu-free Al-6wt-%Si-0.4wt-%Mg alloy, adding Ti to the alloy did not affect the UTS.
Study on the Change of Rainfall Characteristics in Hangzhou’s Urbanization Process
Authors: Zheng Shi , Lin-lin Hu , Huan-Bao Chen , Hong-xia Tang
Published: June 2019

With the development of the economy and expansion of the city size, urbanization has more important effects on rainfall characteristics. This paper takes Hangzhou for example, uses measured data of rainfall stations, and analyses the influence of urbanization on rainfall characteristics. The results show that the urbanization has changed the Hangzhou’s rainfall characteristics, and the heavy rain occurred probability increases, the flood disaster is more and more frequent.
Pilot scale study on medium/low temperature SCR denitration technology for industrial flue gas
Authors: Xiao Xiang , Fang Ping , Huang Jianhang , Wu Haiwen , Tang Zhixiong , Cen Chaoping
Published: June 2019

Based on laboratory research, the titanium-based honeycomb molding catalysts with MnO
x
/CeO2/V2O5 as the main active material were prepared, and a pilot scale study on medium/low temperature SCR denitration technology for ceramic kiln flue gas was carried out on a 5000 m3/h pilot scale equipment. The influences of flue gas flow, ammonia-nitrogen molar ratio and ammonia concentration on denitration efficiency were investigated. The result showed that the medium-low temperature SCR denitration technology had an excellent NO
x
removal efficiency. Under the conditions of the flue gas flow was 3000 m3/h, the ammonia-nitrogen molar ratio was 1.2:1, and the ammonia concentration was 25%, the NO
x
removal efficiency coulld reach 86%, and NO
x
emission concentration and ammonia escape amount were less than 40 mg/m3 and 1 mg/m3 in the flue gas, respectively. The technology can achieve deep reduction of NO
x
in ceramic kiln flue gas, and has a good application prospect.
Comparative Study on the Fractal Dimensions of Soil Particle Size
Authors: Shen Jingfang , Zhang Ying , Ling Chen , Liu Wenwei , Zhang Xu
Published: June 2019

The application of fractal theory provides a new approach for the study of soil science. The calculation of fractal dimension is the basis. The purpose of the study is to find a suitable method for calculating the fractal dimension of the soil particle size and to analyse how the fractal dimension reflects soil properties. We mostly use comparative analysis to study. Comparing the mass fractal dimension method with volume fractal dimension method, we analyze their advantages and disadvantages, and the fractal dimension performance of the soil in different land types.
The application of cracking coefficient method to the study on fractures in volcanic of Anda area
Authors: Yue Zhou , Zhiguo Wang
Published: June 2019

According to the actual situation of volcanic reservoirs in Anda area, this paper uses the comprehensive analysis of drilling and logging data to predict the fracture development of volcanic reservoirs in the study area. Among them, the ratio of longitudinal wave velocity, “crack coefficient” method, is used to analyze and calculate the crack development frequency. The research shows that the fractures of volcanic reservoirs in Anda area are relatively developed, and the characteristics of fracture parameters will inevitably affect the exploration and production of natural gas in this area.
The influence of vehicles load on structural bearing capacity of underground parking garage
Authors: Xijian Liang , Qiuyan Sun , Xingxing Huang
Published: June 2019

For passing vehicles on underground parking garage,the difference between the codes for the bridge design and for the ordinary building structural design in design parameters of materials load combination etc is compared.Specification for Design of Municipal bridge has made the corresponding simplification computation to load function.
Study on the Effects of Carbon Fibers and Carbon nanofibers on Electrical Conductivity of Concrete
Authors: Wang Tengjiao , Xu Jinyu , Bai Erlei , Luo Xin , Chen Haowen , Liu Gaojie , Chang Sen
Published: June 2019

In order to study the effects of carbon fibers and carbon nanofibers on the electrical conductivity of concrete, we adopt the four-electrode method to measure the resistivity of concrete with different test voltages, different ages and different fiber content. The test results show that both carbon fibers and carbon nanofibers can significantly reduce the electrical resistivity of concrete. When carbon fiber content and carbon nanofiber content are same, the resistivity of carbon fiber reinforced concrete (CFRC) is lower than that of carbon nanofiber reinforced concrete (CNFRC). The resistivity of CFRC and CNFRC can decrease with the increase of the test voltage, increase with the development of the concrete, and decrease with the increase of the fiber content. For concrete with an age of 28 days, CFRC has the largest decrease in resistivity when the carbon fiber content is between 0.2% and 0.3%, and the resistivity of CNFRC drops biggest when the carbon nanofiber content is between 0.1% and 0.3%.
Effects of Local Thickening on Surface Precision Control of Membrane Structures
Authors: xiao Xiao , qiao Zhang , qingchun Song
Published: June 2019

It is difficult to maintain the surface flatness like other materials for membrane structure under working conditions, and working performance will be greatly affected due to the extremely low bending stiffness of the membrane. In this paper, the finite element software ABAQUS is used to discuss effects of local thickening on the precision of the membrane structures from three aspects: tilt angles of the wrinkle equilibrium position, out-of-plane deformation of the structures and the wrinkle amplitude of membrane structures were analysed. Also the possible negative effects on the maximum principal stress. By comparing the local reinforcement model with the ordinary model, the accuracy of the local thickening model is far superior to the ordinary model, and little effect on distribution of maximum principal stress. The research results indicated that local thickening membrane structure can achieve better control to surface flatness at a lower cost.
Design and Research on the Information Management System of Qinhuai River Intelligent Pump Station
Authors: Yong Sun , Donglei Wu , Yuquan Zhang , Yuan Zheng
Published: June 2019

The intelligent pump station information management system is located between the computer monitoring system of the pump station and the management information system of the superior management department. Combined with the actual situation of Qinhuai River, this paper presents the design idea, software and hardware structure of the information management system of the intelligent pump station, and introduces the main functions of the information management system so as to provide reference for related construction.
Construction and Application of Sports Towns Characterized by Sports Event Chains
Authors: Zhang Jun , Gan Zhuoting
Published: June 2019

The sports towns’ outlook are strictly restricted by their construction pattern. Different from traditional ones, sports towns characterized by sports event chains is the new and upgraded version. Their competitive advantage include integration effect, synergy effect and brand effect, contributing to better utilize sports resources and social capital input in a comprehensive manner. To make full use of sports event chains during sports towns’ construction, this paper tries to define and analyze sports event chain’s definition, characteristics and function, summarizes its major structural patterns, puts forward some suggestions on implementing sports event chains as well as cites the example of Huangshan Modern Industrial Park to further illustrate the concept.
Construction and Innovation of Guilin Urban Green Rainwater Landscape System from the Perspective of Sustainable Development
Authors: Ren Lili , Wang Jinye , Hao Yafei
Published: June 2019

With the acceleration of China’s urbanization process, there have been many rain and flood problems such as the increase of urban stagnation and serious water pollution. People began to reflect on the relationship between urban green infrastructure construction and ecological nature. As an important part of the urban rainwater system, the green rainwater infrastructure plays an important role in managing urban rainwater, building a benign water cycle in the city, and protecting the ecological environment. The article proposes to build a Guilin urban green rainwater landscape system based on the green rainwater infrastructure and propose innovative suggestions.
Valley deformation and Stability assement of Plunge Pool slope
Authors: ZHANG Xu , ZHOU Shaowu , DUAN Haibo , LI Wendu , ZHANG Cheng
Published: June 2019

In order to study the valley deformation and rock mass stability of plunge pool slope at the Wudongde hydropower station. We analyzed the deformation law of valley base of site displacement monitoring. Based on the finite element method, the slope stability of different typical profiles on both banks and valley deformation is investigated. The numerical and monitoring results of deformation have a good consistency, and demonstrate that excavating and other perturbations can quicken the creep deformation of rockmass. Through deformation monitoring combined with simulation, rock mass stability analysis and evaluation are reasonable. The nonlinear large deformation of rock mass is considered, and the slope safety factor is obtained quickly. Meanwhile, it is convenient to simulate the instability state and failure process of sliding surface with any landscape and arbitrary shape as well as intuition and applicability.
Site test study of pile-soil stress ratio of composite foundation in karst area
Authors: Han Jianqiang , Li Weike , Huang Junguang , Cui Jie
Published: June 2019

Aiming at the special geological conditions in Karst areas, the pile-soil stress ratio of composite foundation is analyzed. According to carry out the field test of composite foundation in Karst area, soil pressure boxes are arranged to measure the stress of piles and soil at the same time. As the load increased, the variation trend of the pile-soil stress ratio of composite foundation is analyzed. On the basic, the pile-soil stress ratio is compared with non-karst area. The test result showed that both the pile-soil stress ratio of PHC piles and high pressure jet grouting piles increase. The increase of the PHC piles is more obvious. The pile-soil stress ratio of PHC piles is larger than high pressure jet grouting piles. The main reason is that the strength of cement-soil mixed piles is lower. The high pressure jet grouting piles plays an important role in improving soil bearing capacity between piles and supporting the side abutment pressure of PHC piles in composite foundation. It is shown that the stress concentration is more obvious in karst area.
Investigation on microstructure of weld metal of HR3C heat resistantsteel afterservice for 50000 hours
Authors: Xinmei LI , Zhongwen ZhANG , Xiulian LI , Baoshuai DU , Wen LI , Shuai SUO , Yuzhong WEI
Published: June 2019

This paper studied the microstructure of the HR3C steel-welded metal having serviced for 500 hours via metalloscopy, scanning electron microscopy and Energy Disperse Spectroscopy (EDS). As the result shows, the HR3C steel-welded metal remains the cellular-dendrite structure after 500 hours of service, with the number of its precipitated phases increased and its size enlarged. The M23C6 carbide is distributed in the strip or lump pattern along the boundaries of afterbirth-like crystals and dendritic crystals, while it is distributed in the form of small particles close to the crystal boundaries. Cu-rich phase, NbCrN- and Nb (C, N) - precipitated phases are highly stable and small, which accounts for the main reason why the HR3C steel welding joint presents high intensity.
Numerical study on dynamic buckling of composite cylindrical shell with one edge simply supported and opposite edge clamped
Authors: Jia-li BIAN , Zhi-jun HAN
Published: June 2019

Considering stress wave effect, axial inertia and rotational inertia are calculated, and dynamic buckling control equation of cylinder shell is obtained by Hamilton principle based on the Donnell thin shell theory. The dimensionless of the equation is solved by differential method, which discuss about effects of different initial imperfection, different impact mass, different impact speed and different lay-up angle on the buckling of cylindrical composite shell. The result shows significant effects of stress wave and axial inertia on dynamic buckling.
Empirical Method and Finite Element Analysis of Deep Foundation Pit Excavation in Ningbo Soft Soil
Authors: Wu Bo , Peng Yiyong , Meng Guowang , Huang Wei
Published: June 2019

How to analyze and judge the excavation deformation of deep foundation pits in cities has become an urgent problem to be solved. Through the analysis of the excavation monitoring data of a deep foundation pit of a station on Ningbo Metro Line 3, the characteristics of horizontal displacement and surface settlement of the ground-connected wall during the foundation pit excavation in Ningbo soft soil area are obtained. And to compare and analyze the monitoring data by the empirical statistics method and the finite element method. Analysis shows that both can predict the deformation trend of foundation pit. However, due to the regional nature of the deep foundation pit engineering, the prediction accuracy of the empirical curve is poor. Compared with the empirical statistical method, the finite element method has better prediction accuracy, but the finite element method is more complicated. The advantages of the two methods can be applied in the project. In the study of deformation prediction of deep foundation pits, a more in-depth study of the combination of the two methods can be carried out.
Model Experimental Study on Support Structure of Double-row Piles in Deep Foundation Pit
Authors: Wang Yibo , Xia Xiong , Wu Yan
Published: June 2019

The model experiment was designed to analyse the bending moment of pile body and earth pressure of double-row piles. The study finds that the influence of different loading conditions on pile bending moment and earth pressure is uniform. With the increase of pile spacing, the positive peak value of pile bending moment increases gradually. The average increment is about 27%.The trend of change coincides with power function. The positive peak value of earth pressure increases first and then stabilizes. The average increment is 11%. The trend of change accords with the quadratic function of one variable. With the increase of row spacing, the positive peak values of soil pressure and pile bending moment first decrease and then increase. The change relation is in accordance with the quadratic function of one variable. The minimum appears between 5.0d and 5.25d. It can be seen that when the row spacing is small, it can be regarded as a single row of piles. With the increase of row spacing, the two rows of piles share the load together. The structure tends to be reasonable. When the minimum earth pressure occurs, the retaining effect of the structure is the best.
Experimental study of preparing CaS from phosphogypsum with lignite
Authors: zhu Liping , Zheng Shaocong
Published: June 2019

The reaction of phosphogypsum (PG) and lignite is complex, which depends on the reaction conditions and atmosphere. In the paper, it was carried out for reduction decomposition of PG to calcium sulfide under N2 atmosphere. Scanning electron microscopy and XRD were used to analyze the raw–material and decomposition solid production. The reaction mechanism of preparing CaS from PG with lignite were analyzed by Factsage 6.1 and thermodynamic analysis. The results indicated that the decomposition reaction temperature were between 800 °C and 1100 °C. These experimental conditions were also studied on Ca/C molar ratio, reaction temperature and reaction time in the N2 atmosphere. The results showed that the optimal result for production of CaS are found to be a lignite to CaSO4 molar ratio of 2.4 to 1, a temperature of 900-1000°C in reductive atmosphere. Under these conditions the conversion rate of CaS from phosphogypsum amount to no less than 97.3%.
Preparation of Sulfonylcalix[4]arene-loaded XAD-7 Resin for Strontium(II) Adsorption
Authors: Liu Cong , Su Guofeng , Chen Tao , Liang Manchun , Zhao Liting , Zhang Dongxiang
Published: June 2019

Sulfonylcalix[4]arene-loaded XAD-7 Resin was prepared and used as an adsorbent for removal of Strontium(II) from aqueous solutions. The adsorption of the metal ions onto SCA-XAD-7 as a function of pH, contact time, metal ions concentration, temperature, and reuses was investigated. The adsorption capacity of SCA-XAD-7 composite towards tested ions reached a maximum at pH values of ∼6. The adsorption has reached equilibrium within 7 h. The adsorption isotherms were well fitted by the Langmuir model, and the maximum values of adsorption capacity of the adsorbent were 28.87 mg⋅g−1. Thermodynamic studies imply the adsorption was a spontaneous and exothermic process in nature.
Drop impact on a superhydrophobic surface with single groove
Authors: Zhan Haiyang , Shan Chengwei , Lu Chenguang , Liu Cong , Wang Ge , Liu Yahua
Published: June 2019

In this paper, we systematically studied droplets with different velocities impact on grooves with different depths. In the experiment, there are four morphological changes of droplets due to the influence of the impact velocity and the groove depth. Different morphological changes show different spreading characteristics. When the groove depth remains unchanged, the increase of impacting velocity promotes the spreading of droplets in the X (perpendicular to the groove) and Y (parallel to the groove) directions. However, when the impact velocity keeps uniform, the increase of groove depth only promotes the spreading of droplets in the Y direction and has little effect on the maximum spread diameter of the droplet in the X direction. The experimental results also show that the contact time is related to the change of droplet morphology, and their relationship is explained at last.
Evaluating the efficiency of sub regional environmental regulations in China
Authors: Fanyong Zhang , Yueping Du
Published: June 2019

Based on the three-stage DEA-Windows method, we evaluated the environmental regulation efficiency of 30 provinces in China from 2000-2015. Environmental regulations were efficient, with a fluctuation of about 0.66, following the order eastern regions > central regions > western regions, with significant differences between provinces. In addition, regulation efficiency was affected by the level of the local economic development, the industry structure, the FDI index, the population density, and the marketization level. Efforts should be made to strengthen environmental regulations, formulate adequate policies, and coordinate the relationship between economic development, industrial structure, FDI, and environmental regulation.
Analysis of attenuation characteristics of carbon nanofibers to 94GHz millimeter wave
Authors: Wang Hongxia , Li Aijun , Hou Weijun
Published: June 2019

In order to investigate the interference characteristics of carbon nanofibers to 94GHz millimeter wave, we established the corresponding electromagnetic field integral operator equation according to the conductivity and dielectric properties of carbon nanofibers, and solved the equation by the method of moments. The mass extinction coefficient of carbon nanofibers to 94GHz millimeter wave was calculated and analyzed. Lamber-Beer law was used to analyze the attenuation characteristics of carbon nanofibers smoke to 94GHz millimeter wave. The relationships between transmittance and size, conductivity, smoke concentration and smoke thickness of carbon nanofibers were obtained. The results show that the optimum conductivity of carbon nanofibers is related to their size. The longer the length of carbon nanofibers is, the smaller the diameter is, and the more significant the attenuation effect to 94GHz millimeter wave is.
Parameter determination for the Mini-Oscillator Model of the Viscoelastic Material
Authors: Huang Zhi-cheng , Wu Nan-xing , Wang Xing-guo , zelun Li
Published: June 2019

The viscoelastic composite structure is widely used in the vibration and noise suppression of thin-walled components. The vibration analysis of viscoelastic composite structures must involve the constitutive equation of viscoelastic materials. The form of the constitutive equation of viscoelastic material has a decisive influence on the dynamic analysis process of viscoelastic composite structures. Since the constitutive relation of the viscoelastic material changes with time, frequency and temperature, the analysis of the dynamic characteristics of the viscoelastic composite structure is greatly complicated. The mini-oscillator model considers the frequency-dependent properties of viscoelastic materials. Therefore, it is widely used in the dynamic analysis of composite structures. Aims at the need of viscoelastic material passive vibration control for viscoelastic composite structures, a method for determining the parameters of mini-oscillator model is proposed. The method obtains the viscoelastic material mini-oscillator model parameters by parameter fitting by the measured viscoelastic material complex modulus data in the frequency domain or other viscoelastic material damping model expressions obtained from experimental data. The results are compared with fractional derivative model. The results show that the mini-oscillator model can correctly describe stress-strain relationship of viscoelastic material and the parameter fitting method proposed in this paper is accurate and effective.
Application of two-dimensional hydrodynamics numerical modelling in mangrove planting of coastal areas
Authors: Wang Lele
Published: June 2019

A two-dimensional numerical model is presented for application in mangrove planting of coastal areas. The model is discretized with finite volume method based on an unstructured mesh and employs the Roe-MUSCL scheme and the predictor-corrector procedure for time stepping. The model is validated primarily by the observed river runoff data at the upstream of the Jiaojiang River and tidal level along the open boundary obtained with the TPXO7.2 global tidal model. It is then applied to study tidal hydrodynamics in the Dachuan River of the Baisha Bay within the Jiaojiang River estuary during the spring, middle and neap tidal cycles in July and August 2016. The model results show well agreements between the predicted and observed tidal level and tidal current process. Finally, referred to existing research on critical tidal level and duration of Kandelia candel planting in coastal areas of the southeast China, a proper planting condition of K. candel seedlings are determined, after adopting the mean tidal level and duration calculated from the model results.
Numerical Simulation and Analysis of Advance Pre-support for Underground Cross-street Tunnel
Authors: Lijuan Sun , Ziqi Jiang , Bingwei Liu
Published: June 2019

In this paper, the excavation process of a cross-street tunnel construction is studied. In order to ensure the normal construction, three kinds of advanced support combination schemes are preliminarily worked out. Scheme one: leading anchor pipe + sleeve driving small pipe Grouting; Scheme two: horizontal rotary jet grouting piles+ sleeve driving small pipe grouting; scheme three: horizontal rotary jet grouting piles+ large pipe shed+ sleeve driving small pipe grouting; Combined with the existing practical engineering cases, using the finite element software ANSYS to simulate the tunnel excavation process and verify the results, the settlement and displacement curves of the surface and vault and the convergence time history curves of the side walls are compared, and the effect of structural stress control is analysed. Among them, the third scheme has great advantages. Therefore, considering all factors, the third scheme is adopted as the pre-support scheme of the tunnel.
Static load test and evaluation of a separated interchange bridge
Authors: Xijian Liang , Qiuyan Sun , Xingxing Huang
Published: June 2019

The separated interchange bridge described in this paper has a large bevel angel and its superstructure is combined steel and concrete girder. The bridge shakes significantly when heavy-loaded vehicles travel on it. Moreover, the box girder has warped upwardly and the bearing has disengaged with the girder body. Therefore, a static load test on the bridge has been performed. By the test, corresponding results have obtained, damage conditions and bearing capacity have been analyzed and evaluated, and measures to prevent bridge defects have been proposed. Finally, a maintenance and reinforcement scheme has been formulated, which has a reference significance for overall inspection and evaluation of the similar old bridge.
An ALE Approach to the Simulation of Perforating Process
Authors: Pang Mingyu , Sun Feng , Liu Bo , Xue Shifeng
Published: June 2019

Perforation is of great importance to improve the oil and gas wells productivity. This research is to simulate the process of perforating based on the structural characteristics of shaped charge jet and the penetration mechanism. The perforating process is analysed with the Arbitrary Lagrange Euler (ALE) method, including the shaped charge initiation, jet formation, and the nonlinear large deformation. In this paper, the jet shape, pressure and velocity are given, the mechanical behaviour of jet penetrating the casing, cement and rock are described in detail. The simulation model and method used in this research are proved to be reasonable and feasible. The result provides a guidance for the real-time research of perforating process.
Primary design and protection of 110kV substation
Authors: Feng X J , Chen Y Q
Published: June 2019

This paper designs a 110KV substation. Through the analysis of transformer load, the capacity and number of main transformers are selected, and the main connection modes of 110kV, 35kV and 10kV are determined. By calculating the short-circuit current, it can be used to select the main electrical equipment to complete the design of transformer protection and the selection of distribution devices, and draw the main wiring diagram and the plane layout. Finally, we design a simple relay protection, and complete the design of the primary electrical part of 110kV substation.
Effect of magnetite on concrete mechanics and microwave deicing performance
Authors: Huang He , XU Jin-yu
Published: June 2019

Magnetite aggregate is used as a absorbing material. In order to study the mechanical properties, absorbing heat and deicing efficiency and frost resistance of magnetite concrete, I prepared the magnetite aggregate concrete with 0, 20%, 40%, 60%, 80% and 100% magnetite content, which be used to measure the compressive strength, flexural strength and surface temperature rise curve of magnetite aggregate concrete under microwave irradiation. The results show that the addition of magnetite aggregate can effectively improve the mechanical properties and deicing efficiency of concrete. With the increase of magnetite aggregate, the compressive strength and flexural strength increase gradually, and is approximately linear with the content of magnetite aggregate. With the increase of magnetite aggregate, the absorption and heating efficiency of magnetite aggregate concrete increases gradually. When the content of magnetite aggregate reached 100%, the efficiency of absorbing heat and deicing increased by 71.3% and 69.7% respectively.
Improving Peak-load Pricing Method for Provincial Transmission and Distribution Network Considering Power Backflow
Authors: Junjie Qian , Dahai You , Bo Ruan , Qi Zou , Hengwei Liu
Published: June 2019

In view of the power backflow phenomenon in provincial transmission and distribution network caused by the fact that more and more new energy power is connected to the power grid, a provincial network voltage level pricing method considering power backflow is proposed. For exactly describing the complex power transmission relationships among various voltage levels in consideration of power backflow, a new power transmission model is proposed. And the balance parameters of the whole transmission and distribution network are gained based on the transmission data. The problems in cost sharing caused by power backflow are analysed and an improving peak-load pricing method solving the problems is proposed. Conceptions of source point transmission and distribution cost (SPTDC) and load point transmission and distribution cost (LPTDC) are defined. Through calculating the LPTDC in each voltage level, the cost apportionment is accomplished. The case study of a certain provincial power network is carried out and the effectiveness of this pricing method is proved. The results show that this method can recover all the transmission and distribution cost of the network and can authentically reflect the influence of power backflow on the transmission and distribution price.
A Stable Energy Acquisition System Based on Magnetic Circuit Coupled Current Transformer for Transmission Line
Authors: Zhang Pengyu , Meng Runquan , Ren Chunguang , Zhang Ying
Published: June 2019

With the development of smart grids, high-voltage transmission line monitoring devices has become a new research hotspot, but the supply of stable energy for monitoring devices is a difficult point. By utilizing of current transformer (CT) to obtain stable energy from high-voltage transmission lines is one of promising approaches, but the current variation range of the high-voltage transmission line is often too large to be transformed linearly by the traditional electromagnetic CT. According to impedance matching principle, a method to regulate the load impedance of a CT is proposed in order to acquire energy effectively from a transmission line and provide stable output power. The method to regulate the load impedance of a CT can be implemented by controlling a single-phase PWM rectifier. It is proved by experiment that the PWM rectifier can be adjusted to supply a stable 20V output voltage and 9W output power for the DC load.
Short-term wind speeds prediction of SVM based on simulated annealing algorithm with Gauss perturbation
Authors: Chen Yan , Chen Rui , Ma Chunyan , Tan Peiran
Published: June 2019

Wind speed prediction is an efficient means to reduce the downside effects of large-scale wind power generation on the grid, but the behaviour of wind speeds is nonlinear and non-stationary, which yields adverse challenge for its prediction. This work proposes a method of prediction for short-term wind speed, which makes Simulated Annealing Fruit fly Optimization Algorithm based on Gaussian Disturbance (GDSAFOA) to optimize the Support Vector Machine (SVM). In the method, Grey Relational Analysis (GRA) is used to select the factors which influence wind speeds prediction. A time series of wind speeds is decomposed by the Ensemble Empirical Mode Decomposition (EEMD). The wind speeds predication is the linear combination of the SVM and the dynamic neural network model based on the nonlinear autoregressive models with exogenous inputs (NARX). This method is applied for the model with wind speeds data measured from a wind farm in China’s Shanxi Province, where results exhibit that the proposed method is feasible and competitive.
The Study on the Key Hardware Development of Single-Phase Photovoltaic Grid-Connected Inverters
Authors: Ma Lei , Sun Jian , Yang Xiaomei , Sang Bingyu , Lin Yandan
Published: June 2019

High-efficiency inverter topology design on single-phase photovoltaic grid-connected equipment is the core of bringing considerable benefits to the society and the investors. In order to study the key hardware design of the inverter that meets the leakage current requirement and achieve the maximum efficiency, this paper analyses the H-bridge based topology (H5 and H6) and DPB topology. Firstly, this paper discusses the working principle of these topologies and concludes that the DPB topology involves fewer MOSFETs than the H-bridge based topology. Additional studies of power device analysis and other component losses in these topologies have concluded that DPB topology typically has lower power device losses at different load ratios. For instance, when the load ratio (Po / Pe) is 100, the power device loss of the H5 topology is 77 W, and the loss of the H6 topology is 68.7 W. Under the same conditions, the loss of the power device in the DPB topology is only 53.6 W.
Application of Beidou Satellite navigation technology in monitoring discharge sewage and exhaust gas of ship
Authors: Xin Guip , Gao Zheng
Published: June 2019

The Beidou Satellite Positioning and Navigation System (BDS) developed by China independently, has unique positioning and short message communication functions. The application of this technology provides a highly reliable and stable operation control method for detecting pollutants discharged from ships. The precise positioning and directional measurement of the ship can also realize the real-time uploading of emission data and the issuance of instructions, which realizes reliable monitoring of ship sewage discharge. This application has a positive effect on the development of China’s Beidou Satellite positioning and navigation system and on seawater environmental protection, and it is also of great significance for the standardization of ship sewage.
Research on Discharging Price of Electric Vehicle Participating in Power Grid Dispatching Considering Reverse Cost
Authors: Tingting Feng , Junqi Zhang , Guangjin Peng , Wenrui Xie
Published: June 2019

As a controllable load and distributed energy storage unit, electric vehicle (EV) can use electric vehicle with vehicle-to-grid (V2G) technology to realize peak load shifting. In order to study the maximum bearing price of the grid in the discharge behaviour of electric vehicles, the paper takes the lowest operating cost of the grid as the objective function, establishes the optimal unit combination model of the standby unit during the peak load. The maximum bearing price of the gird is applied to the maximum cost of scheduling electric vehicle. Then the relationship between the maximum acceptable price and the power of the electric vehicle can be obtained. With the day-ahead load forecast, the upper limit of the electric vehicle acceptable discharge price is obtained. Finally, the simulation and analysis of the proposed method are carried out by numerical examples, and the feasibility and effectiveness of the proposed method are verified.
Detection and Cause Analysis of Structural Defects in Lead Clamp Weld of Transformer
Authors: Li Zhengli , Liu Guangxing , Jian Mingjian , Feng Yunguo , Cui Weitan , Fu Tianmeng , Zhang Ruifeng
Published: June 2019

In this paper, the causes analysis of the cracking accident at the lead clamp weld-fusion line of transformer in the extra-high voltage substation was conducted.

On-site non-destructive detection of weld defects was carried out to determine the size and location of the defects. An anatomical analysis of the clamp sample revealed that there was serious incomplete penetration and incomplete fusion in the internal structure of the weld, which seriously affected the structural strength of the weld. The causes of welding defects were further analyzed, and suggestions for improving product quality and strengthening inspection supervision were put forward.