最新刊期
卷 49 ， 期 3 ， 2017
- 摘要：Abstract:With the development of IT and communication technology,the network environment is becoming more and more complicated, and the perimeters of host and network become dynamic and fuzzy due to the application of cloud computing and visualization technology.At the same time,network attacks become more frequent and advanced network threats with evasive and persistent behavior and profit-chasing are also increasing.However,due to the limit of data source and process ability and device deployment relied on physical environment,traditional network security and intelligence techniques are inefficient on the acquisition capability,analytical abilities and utilize capacity of threat intelligence,and the perception and prediction ability of the network security situation is limited,so it cannot solve the current and future network security challenges efficiently.The chances and challenges caused by big data for network security and intelligence analysis are took as this paper clue.first of all,the connotation of big data is reviewed,and the current dilemmas in network security and intelligence analysis are analyzed,and then the relationship between big data with network security and intelligence analysis is explored,and the changes of traditional security analysis brought by big data technologies are parsed.Big data security analysis,a new security method is formed after the big data technologies was applied in cyber security field.The value of big data security analysis embodies in solving practical problems in network security and intelligence analysis through the methods and technologies of big data analysis under sticking to the purpose of security analysis and the character of security data itself.On the one hand,big data processing technology,such as bulk data processing technology,streaming data processing technology,interactive data query technology,can solve the issues of data processing in the high-performance network traffic real-time restore and analysis,massive historical log data analysis and rapid retrieval,massive text data real-time processing.On the other hand,big data technologies are applied in security visual analysis,security event association and network user behavior analysis,a series research branch of big data security analysis are formed,such as big data interactive visual analysis,multi-source event correlation analysis,user entity behavior analysis,network behavior analysis and so on.Big data security analysis technologies have applied in APT attack detection,network anomaly detection,network security situation perception,network threat intelligence analysis,etc.Even though some achievements have been made in big data based network security and intelligence analysis,the current network security situation is still not optimistic.The effective detection method of advanced network threats and attacks is lacking.The detection and prediction result to unknown complex network attacks is undesirable.The measurement system for evaluation methods of network security situation awareness is needed,and large-scale network security situation awareness indicator system for key assets and entire network is incomplete yet,and the evaluation methods are no pertinence.It is difficult to acquire data from new type data sources of threat information and the standards of threat intelligence sharing are needed to be researched further.Large-scale and integrate threat intelligence center and open service platform aren't yet build.Around the above problems,it needs to be studied that the methods of advanced network threat discovery,complex network attack prediction,large-scale network security situational awareness and threat information collection and sharing technology and needs some key technical breakthroughs such as early detection of advanced network threats,concealment of continuous network communication behavior detection,big data analytics based network feature extraction technology,intelligent-based advanced network threat forecast,non-public network intelligence collection,so as to improve the big data supporting capability for network information security and enhance network information security risk perception and disposal capacity.关键词：big data;network security;intelligence analysis
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发布时间：2023-11-14 - 摘要：Abstract:The splicing joint,as an important connection part of steel truss,its bearing capacity and stiffness are important factors on safety and stability of steel truss.Based on the design of large-diameter silo construction support platform,two types of the splicing joint of angle steel-double T-type beam were proposed.In order to confirm more reasonable splicing form of angle steel-double T-type beam and achieve prefabricated construction of silo construction support platform with large diameter of steel truss,the monotonic load test and the numerical simulation were carried out to study bearing characteristics of the splicing joint and to analyze the bending stiffness,ultimate load and failure mode of two types of the splicing joint under the same load and constraint condition.The results showed that the experimental observations of the splicing joint with web connecting plate is -1.73%,smaller than the splicing joint with web end plate when the load reaches 150 kN under the same constraints,and its bending stiffness is 8.76%,higher than the splicing joint with web end plate.The simulation of the splicing joint with web connecting plate and the splicing joint with web end plate by using the finite element method showed that the plastic deformation of the splicing joint with web end plate is larger when the load reaches the ultimate load of 200 kN,and finally the splicing joint with web connecting plate is buckling failure before member while the plastic deformation of the splicing joint with web connecting plate is larger when the load reaches the ultimate load of 220 kN,and finally the splicing joint with web end plate is shear failure before splicing joint.The splicing joint with web connecting plate is more accorded with the principle of "strong joint and weak member",satisfying the requirements of splicing joint of the large-span steel truss,and the performance parameters of it can provide theoretical basis for the study of the overall performance of the steel truss.关键词：angle steel-double T-type beam;splicing joint;bearing characteristics;bending stiffness;failure mode
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发布时间：2023-11-14 - 摘要：Abstract:There is a higher frequency of rainstorm flood,landslide and debris flow occurring in mountainous area,causing the accumulation of boulders on river beds,changing locally the bed form and flow structure.The experiments were conducted in a moveable channel bed made of sorted sediments with D1=0.025 m and D2=0.07 m,respectively.A down-looking SonTek acoustic Doppler velocimeter (ADV) was equipped to record the rapidly responding flow movement so as to analyze the field turbulence and sediment transport.The bed topography was measured by total station.From the experimental results,it can be concluded that the relative submergence and sediment size exerts a strong control on channel morphology in the vicinity of the boulder,such as the depth,range of scour hole and the deposition height downstream,and there are good linear correlations among the sediment size,the depth,and range of scour hole.The analysis of the experimental data reveals that the velocity in the bottom portion of the flume (down to 0.2 of the relative flow depth (y/h)) preserves logarithmic law:in clear water,and the increase of the relative submergence leads to the reduction of the related parameters of velocity distribution;while the velocity in the bottom portion of the flume is insensitive to the relative submergence with grain underlying.Besides,the mixing process downstream of the boulder causes a considerable variation in the wall-wake zone,which exhibits a steep rise in turbulence intensity and turbulence dissipation at the range of the 1.5 times of the boulder distance downstream,and a gradual recovery with distance downstream of the boulder.The amplitude and region of influence of boulder on turbulence changes with the bed material grain size and the relative submergence.As a summary,the boulders result in dramatic increase of statistical characteristics of near-bottom flow structure and turbulence,which enhance the scouring and siltation,and have an important influence on the water-sediment movement and its stable form.关键词：mountain river;boulder;channel mutation response;flow structure;turbulent intensity
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发布时间：2023-11-14 - 摘要：Abstract:The ventilation effect has a direct influence on the efficiency and security of the construction of underground cavern group.Based on the surge-chamber project of Huangjinping hydropower station,the ventilation plan was dynamically adjusted by the results of numerical simulation and field test.The ventilation flow field simulated by FLUENT showed that the wind speed under the initial ventilation scheme can generally meet the requirements of the specification,while in some corners it was lower than 0.25 m/s.Thus some negative pressure blowers and jet fans have been added at the intersection of the caverns and it is recommended to block the completed upper-construction adit that does not need ventilation.From the measured data,the above measures have achieved the objectives,i.e.,the wind speed in the corner of the chamber has increased significantly,meeting the standard requirement.The on-site test of ventilation showed that the wind speed of the cavern group has a certain increase after the optimization of the initial ventilation scheme.It is found that the wind speed had a negative correlation with dust concentration and temperature.From the trend of changing wind along the cavern,the temperature essentially exceeded the standard of 28 ℃ and the dust concentration significantly outpaced the national standard of 10 mg/m3 when the wind speed was lower than 0.5 m/s in the whole or some sections of the cavern group.Therefore,in order to ensure the quality of ventilation,it was suggested that the wind speed in the underground cavern group during the excavation process should be no less than 0.5 m/s.From the measured data,it can be found that the ventilation environment was complex and the ventilation flow field at the intersection of the caverns was very unstable.Therefore,it was suggested that the similar project should be provided with real-time detection points of airflow elements whenever necessary,and the ventilation scheme should be dynamically optimized according to the field test results to ensure the ventilation quality in all time.关键词：underground cavern group;surge-chamber;construction ventilation;numerical simulation;field test
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发布时间：2023-11-14 - 摘要：Abstract:Pore diameters of wide grading soil are across several orders of magnitude.A preference flow which is a kind of unbalanced infiltration in space usually appears under rainfall infiltration condition.Based on the fractal structure of pores,quantitative demonstration of rainfall infiltration mechanism in wide grading soil was analyzed.According to the theory of fractal porous media and Hagen-Poiseulle equation,the orders of infiltration rate in different pore pipes were different.On this basis,soil pores were divided two regions—a matrix region and a preferential flow region.Their area ratio changed with rainfall intensity.In the matrix region,the infiltration rates of pore pipes were different and all of them reached their own maximum.However,in the preferential flow region,the infiltration rates of pore pipes were the same and they didn't reach their own maximum.The matrix region was composed of small diameter pore pipes and the preference flow region was composed of large diameter pore pipes.The magnitude of infiltration rate in the matrix region was far less than that in the preferential flow region.The expressions of infiltration amount and infiltration rate were developed in two regions.Infiltration features in different rainfall intensities and the relationship between area ratio and rainfall intensity were studied.The results showed that infiltration rate in the preferential flow region was much higher and it increased with the increase of rainfall intensity.The preferential flow phenomenon was produced by the multi-scale pore structure and free infiltration boundary without surface pond pressure.The value and distribution of infiltration rate were influenced by saturated permeability coefficient of soil and the rainfall intensity.The mechanism of a preferential flow was explained from the pores structure perspective.关键词：wide grading soil;fractal theory;multi-scale;preferential flow;rainfall infiltration
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发布时间：2023-11-14 - 摘要：Abstract:It is necessary to explore the measures to reduce the scale of the sandbar and thus to alleviate its blockage impact to main river flow.The influence of confluence angle on sandbar morphology at the confluence with hyperconcentrated tributary flow was investigated through physical model experiments.The confluence of upper Yellow River and Xiliugou River,one of the ten tributaries the hyperconcentrated floods from which resulted in most of the sandbar blocking events,was chosen as the simulated target.The model was designed following the similarity laws for hyperconcentrated river flow.The angles of 90°,60°,30°,and 15° were set as the confluence angles in the experiments.It was found that,with the increase of the confluence angle,the main stream blocking was enhanced.The flow velocity of the backwater area upstream of the tributary river mouth slowed down gradually and the water depth increased.When the confluence angle increased to 30° the recirculation zone was formed and its size was expanded gradually with the increase of the confluence angle,accompanied by the shifting of the high velocity zone towards the opposite bank.The scales of the sandbar in backwater area and recirculation zone both increased with the growing of the confluence angle.When the confluence angle was small,there was no sandbar formed in those two areas,but a sandbar adjoining to the opposite bank of the tributary river mouth would be formed.The scales of the opposite bank sandbar decreased with the increase of the confluence angle.The main channel immediately upstream of the river mouth was blocked by the sandbar in the backwater area,while the main channel immediately downstream of the river mouth was blocked by both the opposite bank sandbar and the sandbar in the recirculation zone.As a whole,the scale of the sandbars in the main channel was the smallest when the confluence angle was 30°.According to the analysis on the sandbar scale and the river bank stability,it is believed that under the current river channel and water-sediment conditions,the confluence angle of 30° is a relatively optimal angle which can reduce the sediment deposition at the confluence.关键词：Yellow River;river confluence with hyperconcentrated flow;confluence angle;sandbar
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发布时间：2023-11-14 - 摘要：Abstract:The discharge consists of both weir flow and orifice flow after opening a flap gate,which brings difficulty to hydraulic engineering design.The previous research was mainly aimed at determining the comprehensive discharge coefficient.To discuss the mutual influence of the weir flow and the orifice flow when they function separately,the physical model experiments were conducted to investigate the influence of the flow and the level of the tail water onto the flow passage ability through the flap gate,under the condition of the maximum opening of the gate.The tests involved the combinations of the flow rates of 0.06,0.08,0.10,and 0.12 m3/s and the levels of the tail water of 0.50,0.55,0.60 and 0.65 m,a total of sixteen testing conditions.The results showed that when the level of tail water was constant,the discharge coefficient and flow rate were positively correlated;when the flow rate was constant,the discharge coefficient and the level of downstream water were negatively correlated.While these findings were based on the maximum opening of the flap gate in this study,more experiments will be carried out to study the discharge coefficients under other conditions.关键词：hydraulic flap gate;weir flow;gate outlet flow;discharge coefficient
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发布时间：2023-11-14 - 摘要：Abstract:This study focuses on building a general nonlinear assessment model for water resources vulnerability analysis using a differential function modeling technique.This paper studies the nonlinear relation between water resources vulnerability and its indicators after performing dimension reduction.The major steps were as follows.First,a dimension reduction model was built based on projection pursuit,and the optimal projection direction was searched by Lagrange function.Second,a differential function model was established on the basis of the characters and features of an assessment function.Finally,a nonlinear function model of water resources vulnerability and its indicators were simulated by computing the equation and estimating the parameters.The model was used to study the variation tendency of water resources vulnerability of Beijing during the period 1979-2012 and the sensitive impact factors of water resources vulnerability were selected.The results were consistent with the situation of Beijing,proving that the model was reliable.After performing an analysis of balance between water supply and water demand,water resources vulnerability in 2012 was evaluated.Under different scenarios of inflows,all the values for water resources vulnerability in 2020 is about 0.88 and water resources of Beijing are in the state of extreme vulnerability without considering transferred and reclaimed water use.After using transferred and reclaimed water,all the values of vulnerability are reduced,but the average reduction rate is only 17%.Our model is free of artificial disturbances,and it is characterized by monotony,boundedness and continuous stationarity.The model can simulate and describe the relation between water resources vulnerability and its indicators quantitatively.关键词：dimension reduction;lagrange function;differential function model;water resources vulnerability;Beijing City
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发布时间：2023-11-14 - 摘要：Abstract:The existing analytical solution of stand-up time neglected the softening effect of underground water,which resulted in overestimating the surrounding rock quality.This paper focused on the softening effect of water on stand-up time for the gypsum rocks with typical softening characteristics.The research method combined the softening test results of gypsum with the axisymmetric circular tunnel elastic theory.Firstly,the softening test of gypsum with different soaking time was carried out;thus,the absorption,elasticity modulus and Poisson's ratio changing over soaking time were obtained,respectively.The integrality index and water content coefficient were introduced into the quantitative relationship between the elasticity modulus and the soaking time and that between the Poisson's ratio and the soaking time; thus,the softening equation of mechanical parameter of rock mass was obtained.Then,based on the elastic solution of axisymmetric circular tunnel and the influence of tunnel face,the displacement formula of tunnel free face without supporting effects was developed.Then,the softening equation of mechanical parameter of rock mass was embedded into this displacement formula;thus,the displacement solution of free face considering softening effects was obtained.At last,the analytical model for stand-up time of rock mass surrounding tunnel with consideration of softening effect was established by introducing the active span and the critical displacement value into this displacement solution.This model takes into consideration the engineering features of rock mass,the mechanical performance of rock,and the softening behavior of rock.Moreover,it is able to show the relationship between the stand-up time and the active span.This model was further investigated by self-consistent analysis,which showed that the variation rule of each parameter accorded with actual situation and the self-consistency was met.This model was employed for the Lirang tunnel,which indicated that it is practical for in-site application.关键词：stand-up time;rock mass classification;softening;tunnel stability;active span;gypsum rock
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发布时间：2023-11-14 - 摘要：Abstract:To further investigate the seismic performance of the exterior joint with partial self-centering friction damped connection in innovative PEC column-steel beam composite frame,axial compression of PEC column and its layout was taken into consideration to design three 1∶1.6 scale specimens and then tests were conducted under quasi-static cyclic lateral loading.Based on test measurements and observation,the specimens' seismic performances were studied,including the load-carrying capacity,bending stiffness degradation,residual drift angle,hysteretic energy-dissipation and load-carrying mechanism of joint.The results showed that post-tensioned bars provided restoring force to realize self-centering function and friction energy-dissipation plates can provide energy dissipation capacity to reduce the structural earthquake response.Axial compression of PEC column increased the initial bending stiffness but its second effect accelerated the energy-dissipation developing process,while the layout of PEC column had little effect on initial flexural stiffness and developing process of flexural stiffness degradation and energy-dissipation.The specimen SMJ-2 exhibited superior self-centering function as its residual drift angle was less than 0.005 rad when test end with the loading drift 3.18%,the specimen SMJ-3 owned sound self-centering function as its residual drift angle was less than 0.005 rad when the loading drift approximately equaled to the inter-story drift limit (1/50) at design based earthquake level and 0.01 rad when the loading drift surpassed the inter-story drift limit (1/30) at maximum considered earthquake level,while the residual drift angle of specimen SMJ-1 was less than 0.01 rad when loading to the inter-story drift limit (1/50) at design based earthquake level,but it was increased with the second-effect of axial compression of PEC column,which led to the decay of its self-centering function.关键词：partial self-centering friction damped connection;exterior joint in composite frame;self-centering function;energy-dissipation capacity;quasi-static cyclic lateral loading tests;seismic performance
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发布时间：2023-11-14 - 摘要：Abstract:The bearing area of yield-type support with two pillars which was obtained based on the plane simplified force system had poor adaptability and could hardly reflected the characteristics of bearing capacity in the top beams except the area where the symmetry plane was located.In order to solve the problems,the "bearing body" was adopted to analysis the characteristics of bearing capacity.Firstly,the outside surface formulas of the "bearing body" were deduced by space force system analytical method with the top beam as the study object and the selecting principles were also analyzed when the bearing faces were overlapped.Then the longitudinal and transverse sections of the "bearing body" reflecting the characteristics of bearing capacity in the corresponding areas were obtained.At last the relationships between the volume of the "bearing body" and the parameters of the support were analyzed.Besides,the above results were contrasted with the existing calculation results.The results showed that,when being selected,the overlapped bearing faces should follow the principle that the support force value of every hydraulic component must be minimum,meanwhile,the support force of pillars must be positive value;the "bearing body" varied with the support height and had a one-to-one correspondence with the support height;both the area and the two extreme points of the longitudinal bearing areas were maximum in the symmetry plane and decreased to the direction of both sides' pillars;the transverse bearing areas could be classified three types based on their distribution characteristics;the volume of "bearing body" could be increased according to increase the distance between the pillars' upper hinge point and the top beam's bottom,the distance between pillars,balance jack's working resistance and its horizontal angle;the characteristics of bearing area in the support's symmetry plane and the influences of support parameters on bearing capacity of support were identical with the existing calculation results.So the "bearing body" could reflect the characteristics of bearing capacity in any area of the top beam and the volume of "bearing body" could be the standard of support parameter optimization.关键词：yield-type support with two pillars;spatial bearing feature;bearing body;bearing areas along length and width direction;quantitative analysis
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发布时间：2023-11-14 -
Experimental Study on Prefabricated Concrete Filled Steel Tube Column and Composite Beam Connections
摘要：Abstract:The connection between concrete-filled steel tube column and reinforced concrete beam in the prefabricated concrete filled steel tube structure has been a complicated issue.In this study,a new type of concrete filled steel tubular column and concrete beam connection was first designed to satisfy the requirement from the prefabricated construction process,enabling the prefabrication of most assembly parts and rapid assembling at the construction site.Five beam-column connection specimens,three intermediate connection and two end connection,were prefabricated.All the five specimens were tested in the laboratory;one of them was subjected to static and monotonic loading in order to check the bearing capacity and deformation capability of the connection,while the other four were tested under cyclic loading.The failure modes,hysteretic behavior,ductility,energy dissipations and degradations of strength and stiffness of the tested specimens were obtained.It was observed that the ultimate failure occurred at the composite beams,conforming to the basic design concept of strong column,weak beam and strong joint,weak member.The recorded hysteresis curves of the specimens with composite beam cross-section of 200 mm×350 mm were relatively plump without apparent knead shrinkage phenomenon,the ductility coefficient varied from 3.77 to 6.60,and the average equivalent viscous damping coefficient was 0.222,revealing favorable seismic energy dissipation capacity.For the specimens with composite beam cross-section of 250 mm×450 mm,the energy dissipation capacity of the connections were not fully developed due to the limited stirrup reinforcement,resulting in shear-compression failure.The length of the stirrup reinforcement district can be extended to enhance the energy dissipation capacity of the connection.Moreover,stable degradation process of strength and stiffness was also demonstrated since most of the strength degradation coefficients of specimens were found to be higher than 0.9.The yielding strength has not been exceeded for all the T-shaped plates in the tested connections,and the design of the T-shaped plate with bending and shear capacities being 1.3 times those of the connected concrete beam is confirmed to be reliable.关键词：beam-column connection;prefabricated;composite beam;seismic behavior- 2868
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发布时间：2023-11-14 - 摘要：Abstract:The Carboniferous-Permian coal-bearing region is the most important coal production base in China,and coal mining is threatened with confined water from the Ordovician limestone aquifer in many coal mines.Aiming at some limitation and deficiency in the current evaluation method about confined water inrush from roadway floor in coal mine,the evaluation method was explored and studied.In the current rock beam method,the main theoretical calculation hypothesis contained: the water-resisting layer was treated as a clamped-clamped beam.The floor water-resisting layer tension failure was caused by tensile stress exceeding the tensile strength of the rock,at the maximum of the beam moment.The influence of pore water pressure on rock damage was neglected,and the thickness of water-resisting layer was calculated using the average tensile strength of the floor strata.Accident data and researches evidenced that there were some unreasonable parts and a big deviation between actual working conditions and calculation conditions,in the main theoretical hypothesis of rock beam method.By analyzing the stress distribution characteristics of the surrounding rock in common rectangle roadway and combining with actual working conditions,the floor strata tension failure model was abandoned and the shear failure model was formulated,then a new rock pillar mechanical model of confined water inrush in rectangle roadway was built.Based on the new rock pillar model,and taking the influence of pore water pressure on rock damage into consideration,a new formula calculating the critical hydraulic pressure that the floor water-resisting layer could withstand was given using limit equilibrium theory.The new formula showed that there was a direct relationship between the critical hydraulic pressure and the thickness of water-resisting layer,average volume-weight,shear strength parameters,pore water pressure parameters and the roadway width,and the critical hydraulic pressure exhibited exponent relation with the thickness of water-resisting layer.The calculation result quite coincided with the measured data,showing that this new method was reasonable and effective.This new method could be used and referenced for study on similar problem of confined water inrush,in other fields of underground engineering.关键词：confined water;floor water inrush;maximum hydraulic pressure;thickness of water resisting layer;rock pillar method
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发布时间：2023-11-14 - 摘要：Abstract:To improve the reliability and scalability of data storage in redundant arrays of inexpensive disks (RAID) storage system,a new kind of storage fault-tolerance method with high fault-tolerance and flexible scalability was proposed,named random RAID.A research on the properties of random matrices in GF(2) was conducted and applied in the RAID storage fault-tolerance system.At first,the stripe parameters were set by the storage environment configuration and fault-tolerance requirement,then a random matrix was created as the generator matrix,with corresponding scale and some specific properties.Finally,the origin data was split into blocks with equal size, and encoded by the generator matrix, then folded into different disks.When there were data loss caused by disk damage or sector failures,the lost data could be recovered by the corresponding parity-check matrix and the remaining encoded blocks with high probability,enabling efficient and reliable data storage.Theoretical and experimental results show that:1) When random probability p=0.5 and the subtraction of row and column δ ≥15,the random high matrix in GF(2) could be full column rank with high probability;2)The encoding parameters of random RAID weren't constrained by the prime or scale of finite field any more.Instead,they can be set flexibly.The fault-tolerance can also be scaled with different fault-tolerance requirements, and allow more error patterns;3)When using uniform random matrix and compared with RS and CRS,the random RAID can improve the speeds of encoding and decoding greatly thanks to XOR operations,especially in large scale coding constructions;4)With the growth of the scale,the random RAID tends to approximate MDS,thus realizing highly efficient storage.Due to the properties of efficiency,reliability and scalability,the random RAID can realize the general construction of RAID storage fault-tolerance system.Moreover,it can be combined with other fault-tolerance technologies to construct RAID storage fault-tolerance system for specific requirements.关键词：RAID;storage fault tolerance;storage system;random matrix
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发布时间：2023-11-14 - 摘要：Abstract:In a wireless digital communication system,a digital receiver was sampled with a fixed system clock.The asynchronous digital inputs may cause symbol time offset.To tackle the issue of symbol timing synchronization,this paper proposed an iterative symbol timing synchronization method by interpolation on autocorrelation coefficients.The proposed method was divided into two steps:coarse timing synchronization and fine timing synchronization.In coarse timing synchronization,the received samples were filtered by a zero-phase filter or a three-phase filter-banks.Then,the autocorrelation coefficients was calculated by using the sliding window autocorrelation of the preamble.When the synchronization threshold was reached,the maximum bin search on autocorrelation coefficients was used to obtain the searching interval for fine timing synchronization.In fine timing synchronization,an iterative method was used in the searching interval.It is necessary to generate the group delay matching filter according to the estimated time offset to compensate the received signal,and the likelihood ratio was calculated by using the least squares approximation function.Finally,the Gaussian interpolation was used to obtain an accurate result.Compared with the traditional methods,the proposed method had a lower computational load in coarse synchronization step.Meanwhile,the iterative searching method was utilized to conveniently provide the precise symbol timing synchronization.Simulation results showed that the proposed method can achieve Cramer-Rao bound at -2 dB with a preamble of 64 symbols in additive white Gaussian noise channel (AWGN);when the SNR was 10 dB and symbol time offset belong to [-1/2~1/2] symbol timing interval,the MSE performance exceed the cosine interpolation method,MMSE interpolation method and polyphase filter-banks method.Also,it worked well in Rayleigh,CCIR moderate channel as well as CCIR bad channel.In conclusion,the proposed method was suitable for wireless digital communication system.The proposed method was suitable for wireless digital communication system.关键词：synchronization;matched filters;autocorrelation;iterative methods;Gauss interpolation
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发布时间：2023-11-14 - 摘要：Abstract:In order to overcome the ill-posedness of image motion deblurring,the existing algorithms usually introduce regularization constraints to narrow the solution space.However,a single regularization constraint may not be helpful to estimate the point spread function and restore the original image.In this paper,the method based on multi-regularization constraints was introduced for image motion deblurring.Firstly,the normalized Hyper-Laplacian prior on the heavy-tailed distribution of the image gradient was adopted as one regularization term of the proposed algorithm.Secondly,the L1-norm of point spread function was adopted as one regularized term to constrain the sparseness of point spread function and Tikhonov regularization was used to ensure the sparseness of point spread function as a regularization term to avoid isolated points in point spread function.Thirdly,since the regularization terms are not differentiable and strictly convex function,the auxiliary variables and splitting method were introduced to solve the constructed energy equation.Meanwhile,the introduced auxiliary variables can be solved by soft-thresholding equation.Lastly,the synthesized and real motion blurry images were used to verify the validity and efficiency of the proposed algorithm.The experiments demonstrated that it improved the accuracy of point spread function estimation and the quality of restored images.关键词：motion deblurring;multi-regularization constraints;split method;hyper-Laplacian prior
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发布时间：2023-11-14 - 摘要：Abstract:In order to solve the problem of dissipativity for memrisor-based neural networks with time-varying delay,a new method was proposed,which combined a reciprocally convex technique with a Wirtinger-based integral inequality.First,to convert memristive neural networks into the conventional neural networks,differential inclusions and set-valued maps were applied.Then,based on the construction of a Lyapunov-Krasovskii functional with a time-delay coefficient quadratic term of the state vector and a triple integral term,the delay-dependent conditions in terms of linear matrix inequalities were obtained to assure the neural networks strictly dissipative.The derivative of Lyapunov-Krasovskii functional is estimated by using a reciprocally convex technique and a Wirtinger-based integral inequality,which can be easily solved via Matlab.Moreover,the proposed method was extended to investigate the passivity analysis of the considered systems.Finally,the comparisons with the available references showed that this method gives an improvement of 5% in optimal dissipativity performances for various upper bounds of delay variation in numerical examples.In addition,in the same time-delay case,the simulations provided the state trajectories of the neural network system with external input and without external input,respectively.It was shown that the existence of external input was certain to destroy the stability of the system from the simulation results.关键词：dissipativity;memristive;neural networks;time delay;Lyapunov functions
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发布时间：2023-11-14 - 摘要：Abstract:It is valuable to recognize the correlation between the skin state index of human face and the type of Traditional Chinese Medicine (TCM) constitution with scientific and quantitative research methods, and from the process perspective of the accumulation of data and the further advance of knowledge discovery in database, the complex dynamic evolution law of TCM constitution and the appearance skin state index would be revealed. A classification model was proposed that combined the good inductive properties of decision tree for small sample data and the high classification accuracy of Bayes algorithm for large sample data. The decision tree and fuzzy Naive Bayes algorithm were fused to optimize adaptively the weight of index under the trend of the test data accumulation from less to more with a better classification accuracy and interpretation performance. The post-pruning way was used to avoid the over fitting of the conventional decision tree. The fuzzy membership function was introduced to the Naive Bayes by defining interval boundary to solve the randomness and fuzziness in testing and classification of skin state index. The results showed that the fusion weights of the proposed classification model could be adjusted dynamically and the classification accuracy would be increased with the increase of modeling data. The classification accuracy of the classification model with 151 data is 86.7%, higher than 83.3% of independent decision tree, 80% of Naive Bayes,and 76.7% of the matched group with 80 data. The dynamic classification model of facial skin and TCM constitution could effectively identify the complex relationship between the facial skin index and the internal type of TCM constitution by utilizing the data information involved in modeling. The classification model has good accuracy and interpretability, which is a beneficial exploration for the scientific and intelligent development of TCM theory based on data-driven.关键词：correlation;information fusion;Decision Trees;fuzzy Naive Bayes
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发布时间：2023-11-14 - 摘要：Abstract:In order to improve the performance for solving constrained optimization problems, a novel constrained virus colony search (VCS) algorithm was proposed. Firstly, self-adaptive α-level comparison strategy was proposed to make full use of the feasible and infeasible solution at the different stages of the algorithm. Then, in order to improve the convergence rate and search ing precision for solving constrained optimization problems, the search equations based on opposition-based learning mechanism were designed for the process of virus diffusion in VCS. It was mainly used to improve the population diversity and convergence of the algorithm. Finally, the comparative experiments on thirteen CEC2006 benchmark functions showed that the proposed algorithm possessed more distinct advantages on searching accuracy, convergence rate and stability compared with αSimplex algorithm, particle swarm-assisted genetic algorithm (PSGA), crossover-based artificial bee colony (CBABC) and constrained optimization based on modified differential evolution (COMDE) algorithm. Meanwhile, compared with COMDE algorithm, the successful application in unmanned aerial vehicles (UAVs) cooperative path planning constrained problem verified the superiority of the proposed algorithm in the aspects of planning efficiency and threats avoiding.关键词：virus colony search algorithm (VCS);constrained optimization;self-adaptive;α;-level comparison strategy;opposition-based learning;UAVs cooperative path planning
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发布时间：2023-11-14 - 摘要：Abstract:Due to the rapid development of civil aviation transportation business, the contradiction between transportation demand and airspace resource capacity has become increasingly prominent, and the proportion of flight delay has been increasing year by year. As the main means of air traffic flow management, arrival flights scheduling can effectively decrease the flights delay and economic losses, and improve the utilization of the runway. To solve arrival flights scheduling, a mathematical model of multi-runways arrival flights scheduling based on minimizing total delay time was constructed, and a self-adaptive differential evolution algorithm with elite archive (EASaDE) was proposed by adopting elite archive strategy and control parameters adaptation strategy. In EASaDE, the elite archive strategy is used to divide the current population into elite population and non-elite population, and the elite archive strategy is used to divide the current population into elite population and non-elite population, and some individuals involving mutation operation are from the elite population and the remainders are from the non-elite population. The control parameters adaptation strategy utilizes the number of individual evolution stagnation to adaptively adjust the control parameters values, which are applied at the individual level. To evaluate the optimization performance of the proposed EASaDE, a total of 9 Benchmark test functions commonly used and dual-runways arrival flights scheduling were used to carry out comparison experiments.The optimization results of Benchmark test functions showed that the optimization performance of EASaDE is better than the baisc DE algorithm and the other improved DE algorithms. In addition, he optimization results of dual-runways arrival flights scheduling indicated that the total delay time obtained by EASaDE is more smaller and the scheduled arrival sequence is more reasonable when compared with the other optimization algorithms. Therefore, the proposed EASaDE has higher convergence precision, faster convergence speed and better robustness, and thus can effectively decrease the total delay time of arrival flights sequence, improve the throughput of the runways, and relieve the scheduling pressure of the controllers.关键词：arrival flights scheduling;independent approach;differential evolution;global optimization;elite archive
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发布时间：2023-11-14 - 摘要：Abstract:While the evaluation task of microblog emotion is a multi-label classification problem,the traditional text representing methods,which are usually based on vector space model,fail to provide more effective semantic features.Word embedding technology is based on deep learning,which can well capture the syntax and semantic relations between words,and build sentence representing effectively according to semantic compositionality.A multi-label emotion classification system was proposed.First,word embedding for Chinese words was learned from a large scale of unlabeled Chinese microblog text dataset.Second,the Convolution Neural Network (CNN) model was exploited to train a supervised multi-emotion classifier.Third,the learned CNN model was used to composite the feature vector for sentences from microblog.At last,these sentence vectors were treated as semantic features to train the multi-label classifier,which was used to finish the multi-label emotion classification for microblog.Based on the open dataset from microblog emotion evaluation task of NLPCC (Natural Language Processing and Chinese Computing) conference in 2013,the best performance of the proposed system achieved 19.16% and 17.75% improvement in the loose metric and the strict metric,respectively,comparing to the best performance of all the evaluation results.The state-of-art performance,which was achieved by the method of exploiting Recursive Neural Tensor Network model to composite the sentence vector,was also outperformed by the proposed system up to 3.66% and 2.89% on the two metrics.Several multi-label classifiers were employed to compare different feature representing methods,and the sentence vectors based CNN feature space were showed to have the most discriminative emotion semantic.The pattern recognition in the semantic composition procedure was showed by analyzing the training iteration of CNN model.关键词：emotion classification;multi-label classification;word embedding;convolution neural network;semantic compositionality
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发布时间：2023-11-14 - 摘要：Abstract:Considering the complexity and diversity of customers' travel habits,the charging piles need to be allocated appropriately to satisfy the charging demand.Firstly,Markov chain is used to describe the variation of battery state of charge on electric vehicle owners' trip in the whole day,according to three decision-making behavior including driving,charging,neither charging nor driving.Then the real-time charging behavior in the process could be determinated,which indicates the fast and slow charging demand of different vehicle types.Considering mobility characteristics of electric vehicles and the number of different types of electric vehicles in different time periods in some area,the total load demand could be forecasted.The optimal allocation model for charging piles is proposed and aims to minimize investment and operating costs for the charging piles.The mobility characteristics of electric vehicles are integrated into the constraints,and the model is solved by the particle swarm optimization algorithm.The effectiveness and feasiblility of the proposed method are verified by the 33-bus four-area case study on the charging load forecasting and optimal allocation of charing piles.关键词：electric vehicle;Markov chain;charging demand;mobility characteristics;charging piles
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发布时间：2023-11-14 - 摘要：Abstract:In order to mitigate the complex congestion problem of urban power transimission network, a load transferring strategy for high-level voltage distribution network (HVDN) with a novel bi-level programming model based on functional units (group) was presented. In the bi-level model, the upper model was designed to guide the reasonable load allocation of the system and balance the transformer capacity and load, so the channel allocation factor and load-capacity coordination were both taken as the particle coding of PSO, and then the load pre-allocation of the system was determined by the channel allocation factor and load-capacity coordination; The lower model was established to reflect the closing degree of the channel allocation factor and the actual load distribution identified by available power supply marix. Therefore, the actual load allocation and load-capacity coordination of the lower model whould be close to those of the upper. The objective function for the whole model was the sum of the upper and lower, where the load pre-allcation and feedback were interactively executed and the optimal balance of the system load whould be got under the power flow checking. At last, the transferring sequence was determined by fuzzy evaluation with discrete binary code to assess the operational security which is the best scheme of continues operation. The proposed model can be efficiently solved for online analysis and was verified by using the practical HVDN of an urban power system.关键词：high-voltage distribution network (HVDN);load transfer;functional units (group);PSO;fuzzy evaluation;transfer sequence
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发布时间：2023-11-14 - 摘要：Abstract:New insights were presented through systematic experiments for the coalescing behaviors of oil-droplet swarms on the surface of inclined plates and the intensifying mechanism of oil-water separation with plate pack.It is found that when arriving at the inclined plate,the oil-droplets clinging to the surface of plate will not form a continuous oil film as usually regarded,but a rugged surface consisting of dispersed droplets.The subsequent oil droplets will not coalesce directly into this layer.Large oil droplets will roll upwards on the surface of droplets-layer and then leave the inclined plate,while small oil droplets will be retained in some hollow place of the rugged surface and finally coalesced and separated from water after some time period,during which four consecutive stages took place:film drainage,coalescence and growth,forming a random channel,and leaving the plate.The principle of plate pack intensifying the separation of small oil droplets comes from three aspects:shortening the ascending-time that oil droplets arrive at the plate;providing the rugged surface composed by dispersed droplets so that the small oil droplets can find suitable places to stay and complete the coalescence process;offering sufficient coalescence area for small oil droplets.This principle explains the experimental results well for the separation of small size oil droplets.To some extent,the increase of the plate pack length leads to an increased coalescence area,while the decrease of the inclined angle of plate will benefit to the coalescence of oil droplets,and both helps improve the separation efficiency.关键词：oil-water separation;inclined plate;coalescence mechanism;separation efficiency
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发布时间：2023-11-14 - 摘要：Abstract:With the widely used of polyallylamine in many areas,such as dyeing and finishing,water treatment,gas adsorption,the demand of polyallylamine is growing.However,there is a serious chain transfer reaction by directly polymerizing the monomer of allyl amine to get polyallylamine,so it is unable to get high molecular weight products.And also,the experiment is cumbersome by using hydrogenation methods to prepare polyallylamine.Therefore,it is necessary to develop new methods to prepare polyallylamine.Using allylamine hydrochloride as monomer,(NH4)2S2O8 and NaHSO3 as initiating systems,Poly(allylamine) was prepared through the free radical polymerization at 50 ℃.The structure of poly(allylamine) was characterized by 1H-NMR and Fourier transform infrared (FTIR) spectrophotometer.The results of FTIR showed that the peaks at 997 cm-1 (due to C=C bonds) and 945 cm-1 (due to =C-H bonds) disappear after polymerization.The 1H-NMR showed that there are three different hydrogen atoms on the prepared polyallylamine.The results of FTIR and 1H-NMR indicated that the polyallylamine was successfully synthesized.The polymer reaction with hydrogen sulfide was studied and UV absorption spectrum indicated the wavelength of maximal absorption peak has redshift after reaction as well as the absorption intensity was increased.Energy Dispersive X-ray Detector (EDX) showed that there has sulfur at the surface of polymer after exposed to H2S with 1min.Besides,the result of EDX showed that there is 4.62 percent of sulfur atom on the surface of polymer after reacted with H2S.X-ray photoelectron spectroscopy (XPS) confirmed that there has chemical reaction and physical adsorption when the polymer exposed to H2S atmosphere.关键词：Poly(allylamine);radical polymerization;hydrogen sulfide;allylamine
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发布时间：2023-11-14 - 摘要：Abstract:WPU/inorganic composite material has been taken as a kind of promising materials,since it has both advantages of organic and inorganic materials.However,the structural difference between organic and inorganic materials resulted in bad compatibility.The bad compatibility not only restricted the function of inorganic particles in polymer,but also caused the inhomogeneous structure as well as inferior properties of composite materials.Thus,good dispersity of inorganic particles in polyurethane was the key factor for obtaining WPU/inorganic composite with excellent properties.The WPU/SiO2 composite emulsion was prepared by sol-gel process,which consisted of an aqueous silica sol with highly branched structure (KS560) and (3-aminopropyl) triethoxylsilane (APTES)-terminated waterborne polyurethane (WPU).The degree of neutralization (DN) of composite emulsion was controlled by the mole ratio of Triethylamine (TEA)/2,2-Dimethylolpropionic acid (DMPA),and the effect of DN value on structure and properties of WPU/SiO2 composite was investigated.The chemical crosslinking between WPU and KS560 was confirmed by 29Si NMR and rheological test.In rheological test,the storage modulus of composite emulsion reduced with increasing the DN value,since it increased the crosslinking efficiency of WPU and KS560.SEM images found that the addition of KS560 could transfer the stress and prevent cracks in film formation.The smooth of composite film also improved with increasing DN value.Moreover,the polysiloxane network was introduced into WPU by KS560,which would improve the thermal stability,water resistance and mechanical properties of the WPU/SiO2 composite.When the DN value was 80%,the minimum water absorption of composite was reached to 4%.In addition,an increase in DN value could promote the interaction between WPU and KS560,KS560 and KS560,thus the tensile stress and modulus of WPU/SiO2 composite were improved.关键词：aqueous silica sol/WPU composite polymer;crosslinking performance;the degree of neutralization
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发布时间：2023-11-14 - 摘要：Abstract:Computer-aided manufacturing approach for silicone prosthesis with two-component silicone rubber was studied and modeled by 3D modeling.The model was based on temperature,material parameters and geometric features for body and normal mice.The temperature difference between mold and prosthesis surface was discussed by numerical simulation on the temperature field of die and prosthesis.The feasibility of the modeling in repairing the soft tissue defect of chest wall was validated by applying phantom load from softness and fatigue life.The verification was based on finite element method.The test feasibility was based on printing material and manufacturing process.The mold were manufacturing by 3D printing.The test were carried out based on the effects of mucosal and crosslinking reaction efficiency in die at 5,25 and 60 ℃.The effects of prosthesis softness,viscosity and stripping time were discussed by choosing different ratio of silicone and curing agent and temperature.The ratio and temperature were determined by optimizing data in the least square method and examing the regression equation prominence.The results showed that the prosthesis is affected by ratio,but not by temperature within certain range.The soft prostheses are generated when the ratio is set in 10∶0.43,and at 55 ℃.关键词：silicone prosthesis;3D modeling;finite element method;3D printing;ratio;mold temperature;optimization analysis
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发布时间：2023-11-14 - 摘要：Abstract:Aiming at the problem of serious degradation of image in the weather of fog and haze, this paper analyzed the relationship between the atmospheric visibility and the visual distance of the vehicle driving, and established the linear regression formula of the visual distance of the vehicle driving under the hazy weather and the transmittivity rapid estimation model based on the atmospheric visibility, according to the severe degradation issue of the vehicle-mounted video image in the hazy weather; at the same time, according to the dark channel features of the objective image, a fast estimation model of atmospheric light is constructed. It built the rapid estimation model of the airglow by using the guided filter and the box filter and solved the problem of method of the dark channel priori theory hypothesis of the "the sky area" and the time complexity is difficult to adapt to the onboard video image processing problems. It proposed a new hazy weather video image dehazing algorithm with good robustness and strong instantaneity. Then designed the video image restoration processing comprehensive verification platform, which conducted the evaluation comparison on the image recovery quality of the theoretical method presented by this article and the current typical dehazing method through the comentropy and image edge detection, gained good processing effects.关键词：visual distance on vehicle;airglow rapid estimation;defogging algorithm;guided filter;box filter
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发布时间：2023-11-14 - 摘要：Abstract:Segmented anode structure is always used to the structure design of the laminar plasma torch to avoid the large scale shunting,which would result in a pulsation of the laminar plasma jet.However,when the length of the inter-electrode is longer than its limitation,a new anode attachment and a new cathode attachment always appear on the inter-electrode,which is named as double arc phenomenon.The double arc phenomenon leads to a serious heat load of the inter-electrode,resulting in a serious ablation of the inter-electrode and a fluctuation of the plasma jet.In order to prolong the service life of the inter-electrode and improve the stability of the plasma jet,the double arc phenomenon should be avoided.Firstly,based on the assumptions,the analysis models of the laminar plasma torch working with normal condition and double phenomenon were built to analyze the underlying mechanism of the double phenomenon.Besides,according to the principle of minimum voltage,the design requirements of the inter-electrode to avoid the generation of double arc were derived.Then,based on the above analysis,the measures of suppressing the double arc phenomenon were proposed,which included improving the cooling channels of the plasma torch to optimize the cooling effect of arc chamber wall,then decreasing the temperature of the cold layer;increasing the working gas flow rate to enhance the arc compression,which could increase the thickness of the cold layer;limiting the axial length of the inter-electrodes to decrease the corresponding arc voltage drop.关键词：laminar plasma torch;double arc;suppressing measures
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发布时间：2023-11-14
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