最新刊期
卷 45 ， 期 Z2 ， 2013
- 摘要：Abstract:Base on the differential control equations of the coupled thermo-hydraulic (TH) processes of fractured rock masses, with the fracture network seepage method and Numerical Manifold Method (NMM), the temperature field which considered fractures and the relationship between covers and fracture network are analyzed. Then, with the values of node water heads and cover temperature functions, this paper presents the NMM for coupled TH of fractured rock masses. The proposed method uses the relationships between meshes, covers and manifold elements of NMM, which can solve coupled TH under the same mathematical meshes. Furthermore, because the fracture network of seepage intersects with material boundaries undoubtedly, the mathematical meshes are free in any situations, which can avoid the problem of divide meshes in fractures, therefore, the proposed method especially applicable to simulate the coupled problem in fractured rock masses. At last, some examples are calculated to illuminate the valid of this method.关键词：rock mechanics;fractured rock masses;thermo-hydraulic coupling;Numerical Manifold Method(NMM)
- 1791
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发布时间：2023-11-14 - 摘要：Abstract:Based on the local analysis method, the sensitivity of 3 parameters (drag coefficient, eddy viscosity coefficient and secondary flow coefficient) in Shiono and Knight Method (SKM) is studied. The parameters sensitivity to both cross section velocities and conveyance capacity are calculated. The results show that the parameters of main channel are more sensitive than the flood plain. The parameters of main channel to cross section velocities are more sensitive than to the conveyance capacity, while the parameters of floodplain are just contrary to that. For SKM model, the secondary coefficient is nonnegligible to calculate both cross section velocities and conveyance capacity, and the selection of main channel parameters is more significant than floodplain for the accuracy of simulation results.关键词：compound channel, vegetation, velocity distribution, sensitivity
- 2414
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发布时间：2023-11-14 - 摘要：Abstract:The stability of a gravity dam against sliding along deep-seated weak planes is an important problem encountered in the construction of dams. And the study of failure mode is an important part in the stability analysis on deep-seated planes of gravity dams. The commonly used method for the study of failure mode of deep-seated sliding of gravity dam under static load at present is qualitative method that is dependent on analysts’ engineering experience. And the result under earthquake condition is relatively infrequent at present. Based on this status, a program relying on consequences under static conditions which combines results of model experiment and numerical analysis, quantitative and qualitative analysis is used in the study of failure mode of deep-seated sliding of Tingzikou project in this paper. Finally, three possible paths of sliding were acquired and the emergency capacity of different sliding paths was gained.关键词：gravity dam;earthquake;Stability against sliding along deep-seated weak planes;Failure mode
- 1501
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- 4
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发布时间：2023-11-14 - 摘要：Abstract:This study focuses on influence of Reynolds number on characteristics of cavity flow using Particle Image Velocimetry (PIV). Results show that time-mean velocity fields display same structures at different Reynolds numbers, namely, main flow and backflow vortex structures. The maximum vorticity locates at the entrance corner, and high value vorticity gathers in the boundary separation zone. At the impinging corner, values of turbulent intensities and Reynolds stress reach maximum. The stream-wise lengths of high value zone of turbulent intensities and Reynolds stress increase with the increase of Reynolds number, but it is opposite to low value zone in the entrance corner. Distribution forms of characteristic parameter of longitudinal and vertical spectrum resemble each other at different Reynolds numbers. Variation of Reynolds number results into mixing range changes of backflow and characteristic changes of the incoming flow, which will influence the distribution of spectrum in the cavity.关键词：PIV;Reynolds number;cavity flow;flow characteristic
- 2533
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- 2
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发布时间：2023-11-14 - 摘要：Abstract:The goal of this paper was to quantify the influence of two different types of green roofs (a native green roof named green A,an international popular green roof named green B) in building energy benefits by field experiment in Chengdu,China.The temperatures of green A,green B and a non-vegetated concrete control roof(concrete R) had been continuously monitored for a period of 1 year.Results indicate that:(1)In summer and winter,green roofs,compared with concrete R, improved the energy efficiency of buildings,the internal surface average temperature of green A and green B respectively reduced by 1.6℃ and 1.2℃ during the period between June and August,and increased by 2.1℃ and 2.8℃ during the period between December and January.Due to the differences of the substrate layer and the drainage layer,the cooling effects of green A was slightly better,and the internal surface temperature of green A had smaller amplitude in summer,but the insulating effects of green B was better in winter.(2)Green roofs can significantly reduce the peak and the amplitude of the external surface temperature in summer,which was beneficial to prolong roofs life.(3)The effects of solar radiation was weakened by vertical layers of green roof from top to bottom,and the response to solar radiation was delayed layer by layer.At night,the temperature of each layer was stable and the temperature differences among layers was small.(4)Vegetation and substrate layers played a key role in thermal performance of green roofs.关键词：green roof;energy efficiency;temperature distribution;extensive roof;field measurement
- 1775
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- 4
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发布时间：2023-11-14 - 摘要：Abstract:In order to improve the rate of rainwater utilization, reduce seasonal drought on agricultural production and impact of Sichuan Province, the precipitation stability and variety trend are analyzed by the monthly precipitation data from 9 sites in hilly area of central Sichuan during 1960 – 2010. The cumulative filter method and m-k rank correlation method are used to describe the precipitation trend from the angle of qualitative and quantitative; With runs and range theory , wetness-dryness and persistent of precipitation is analysed; Based on morlet wavelet and precipitation concentration index, the stability of precipitation in the temporal and spatial variety are portrayed. Results indicate that: rainfall rank correlation coefficients in hilly area of central Sichuan Basin were less than 0, precipitation decreased, but the trend is not obvious; Precipitation concentration index and Hurst index were respectively changed between11.6 - 14.2 and 0.54 - 0.79, with seasonal variation characteristics and strong continuity; Hilly area of central Sichuan basin precipitation has 5a, 9a, 21a around the main cycle, in which periodic oscillation of 9a is strongest, variation of precipitation is stable.关键词：hilly area of central Sichuan;precipitation;temporal and spatial variation;trend;stability
- 2442
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发布时间：2023-11-14 - 摘要：Abstract: Based on the standard of incipient motion of uniform sediment, the incipient probability was deduced by the concept of sediment angle of repose and the random theory,we can alse obtain the incipient velocity of uniform on different bed slopes. Through the comparison with the former research, the result shows that this formula can be not only used in large gradient channels,but also used in the common chnnels.At the same time,this study peliminary analysis the difference of the typical incipient formulas of uniform sediment.
- 1764
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- 2
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发布时间：2023-11-14 - 摘要：Abstract: Flow resistance in gravel-bed rivers is usually investigated by considering variation in relative roughness height, while relevant friction law for the porous permeable layers is not well understood. By applying Ergun equation, this study investigated the friction law of seepage through packed beds composed of glass beads. Different flow regimes were observed with varying head loss measured. The results show that the friction factor decreases with increasing Reynolds number and the data collected for different cases collapse almost into a single curve when the wall effects are considered. Finally an improved Ergun correlation is proposed to evaluate the flow resistance of packed permeable beds with small bed-to-particle ratios.关键词：seepage;porosity;hydraulic radius;friction factor;wall effect;Ergun equation
- 1961
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- 4
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发布时间：2023-11-14 - 摘要：Abstract:It is easily to develop a landslide or debris flow in mountain area because of the earthquake or the rainstorm. After the disaster, a large congeries can often be formed in the river bank，which can cause large influence on sediment scouring and deposition in the river reach. Based on the movable bed experiment and some results gotten from fixed bed experiment, the relationship between river bed deformation and velocity distribution was studied. The range of the scour and deposit area and the position of the maximum scour pool according to different inflow condition and different dimension of congeries were analyzed too. It was found that the main conclusions are as follows：The scour area would appear at downstream the edge of the congeries，and the deposition area often appear in the recirculation zone downstream the congeries. The range of the scour and deposit area would increase with the increasing of flow discharge. The bed deformation around the congeries was caused by the contraction and turbulence of flow near the congeries，and the maximum scour position was influenced mainly by flow expansion and adjustment. The maximum scour and deposit position mainly influenced by inflow condition，but the distance between the two positions was mainly affected by the size of the congeries.关键词：congeries;movable bed experiment;the range of the scour and deposition;characteristics of sediment scouring and deposition
- 1741
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发布时间：2023-11-14 - 摘要：Abstract:Using a conceptual model test to explore new type of hydraulic flap gate mixed discharge capacity of weir and orifice flow, getting the relationship of opening degree, flow, and the water level, proposed a method of calculation the mixed discharge capacity of the hydraulic flap gate, which is the correction coefficient method. The test results indicated the common comprehensive discharge coefficient method has good accuracy, which polynomial fitting is the best, linear fitting is followed, and exponential fitting is relatively low; the formula of the correction coefficient has higher accuracy and better practical applicability compared to common comprehensive discharge coefficient method. The researching findings of the experiment provide a certain reference to the flap gate design and application.关键词：hydraulic flap gate;discharge capacity;correction coefficient;comprehensive discharge coefficient
- 1655
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- 6
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发布时间：2023-11-14 - 摘要：Abstract:The wide gradual channel is a common form of natural rivers. The flow structure was measured in the physical model of the wide gradual channel using Acoustic Doppler velocimeter. The results show that the flow presents different evolutions between the local diverging sections and converging sections. The scales of the streamwise velocity and the secondary flow of the upper layer decrease in diverging sections, however, the later shows the inverse variations in converging sections. In addition, the flow separation occurs in the whole lotus root shape channel.
- 1689
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- 2
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发布时间：2023-11-14 - 摘要：Abstract:In order to investigate the performance of Rank Set Pair Analysis (RSPA) in predicting groundwater dynamics and its response to the abovementioned two parameters, a series of scenarios were carried out by using the long-term groundwater table records in the Jingtai site of the Baiyin county, Gansu Province. First, the size of historical set T was assigned as one of eight different values ranging 3 to 15 respectively. The effect of historical set size on prediction error was studied, in the case of single subsequent value. Then, by keeping historical set size T fixed, the influence of number of subsequent value n on prediction error was investigated. The study revealed that, firstly, when historical set size was less than 8, the error was steady and acceptable and when the size became greater than 8, the error might remarkably increase; secondly, RSPA performed well in predication of groundwater dynamics within a short term, however, poorly in predicting a long-term dynamics of groundwater; thirdly, RSPA had serious disadvantage in error accumulation occurred in every step; and fourthly in comparison with single subsequence value, the multi-subsequence value could make the accumulation of error of RSPA increases slowly, yet, it still could not fulfill the requirement of predicting a long term groundwater dynamics.关键词：Rank Set Pair Analysis (RSPA);groundwater;groundwater dynamics;prediction
- 1737
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- 4
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发布时间：2023-11-14 - 摘要：Abstract:Step-pool system widely occurs in high gradient mountain rivers. Step-pool system dissipates flow energy efficiently, thus creates high resistance and stabilizes the stream bed. This paper studies the energy dissipation ratio of step-pool system in different flood discharges for a better understanding of variation of energy dissipation ratio of step-pool system. Two types of step pools structures were modeled in the experiment and the energy dissipation ratios at different flood discharges were compared for better design of step-pool system. The experiments were done in the JiangJia Ravine in Dongchuan, Yunnan province. A channel mimicking the natural rivers was dig on the debris flow deposit of the ravine. The different flood discharges were created by a manmade pond in the upper reach of channel. The step-pool structure was made of boulders of 0.3-0.5m in diameter. The first type of the step-pool system is a single step and a deep pool, the step of this type is constructed with 7 key boulders. The second type of the step-pool system is composed of several steps and a relatively small pool. The first type is much more in three dimensional than the second type. The results show that the energy dissipation ratio of step-pool structure is as high as over 90%. The role of energy dissipation of the structure becomes smaller as the flood water inundates the whole structure, thence the energy dissipation ratio reduces with the flood discharge. The first type of the step-pool has higher energy dissipation ratio than the second type at various discharges. Better design of a step-pool structure may reach the highest energy dissipation ratio.
- 2037
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- 2
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发布时间：2023-11-14 - 摘要：Abstract:For analyzing the scale and dynamics characteristics of spanwise vortexes in open channel flows, instantaneous velocities were measured with high-speed PIV in steady uniform flow at 6 cases. Vortex extraction method was employed to identify vortexes and a simple and objective method was proposed to analyze the radii and circulation characteristics of spanwise vortexes. The scale and circulation of the vortex is only related to the location, and there was no relationship with the Reynolds number or other factors. The mean scale of vortex increases from near wall to the upper boundary of log layer. By the suppression of free surface, the vortex radius gradually decreases above half of the water depth. The average circulation of the vortex generally decreases from the wall to the free surface due to the effect of viscous. The scale and intensity of retrograde vortex are both inhibited by the mean shear, and its average radii and circulation are less than the prograde vortex in the full field.关键词：open channel flows;spanwise vortex;scale;circulation;PIV
- 1925
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发布时间：2023-11-14 - 摘要：Abstract:Experiments are carried out with high-speed photography to observe the developing course of spark-induced cavitation bubble under the impact of the nearby wall. Then, research has been made to study the evolution of cavitation bubble near the wall, the sputtering phenomenon as well as the rebounding phenomenon. Result shows that on the condition that the bubble-wall dimensionless distance is less than three (γ < 3), Cavitation bubble does not move towards the rigid wall in the expansion stage, but starts to in the contraction stage. The experiment also shows that as γ increases, cavitation bubble moves decreasingly to the rigid wall. At the same time, the late movement process of cavitation bubble near the wall is filmed with higher photo-frequency, and experiment shows that when the bubble-wall dimensionless distance γ(γ≈ 1) is relatively shorter, phenomenon of sputtering and rebounding is spotted on cavitation bubbles due to the effect of the rigid wall appeared.关键词：cavitation bubble;cavitation erosion;micro jet;shock wave;high-speed photography
- 1593
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- 2
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发布时间：2023-11-14 - 摘要：Abstract:This paper is to establish an empirical model to calculate the breach parameters of landslide and debris-flow dam under natural conditions for the first time, including the average width bc and the residual height Hd of the breach, and its purpose is to predict the outburst flood peak discharge and maximum water depth caused by the dam-break, so as to provide a scientific basis for the development of disaster prevention and mitigation programs or contingency plans for the lower regions. Based on lots of field works, the data is collected, as well as the analysis of the dam-break characteristics is discussed. Then we select the major factors, including dam height H, dam width B, volume of the dam-lake W, unit volume of the dam in longitudinal V, coefficient of internal friction angle tan and upper limit particle size d90, which affect the breach of landslide and debris-flow dam, to establish empirical relationships between factors (the average width bc and the residual high Hd of the breach). Finally, the empirical model is applied to the instance test, and the result is acceptable.关键词：landslide;debris flow;dam break;dam breach
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发布时间：2023-11-14 - 摘要：Abstract: In every big flood, there will be a lot of landslide on both sides of the river, but currently flood process of landslide seldom research. In this paper, we based on the limit analysis theory, established landslide model of the curved surface under the action of flood, studied the effect of different parameters effect on landslide stability, found that: along with the surface water level increasing stability coefficient of the landside increased, with the rise of groundwater level stability coefficient of landslide is reduced, under the double action of landslide groundwater and internal friction angle of soil, internal friction angle between 15 °and 25°, the landslide has a failure process. As the scour depth increasing stability coefficient decreased. As the slope increasing, the influence of depth of scour on the stability coefficient is reduced. Compared with other parameters, scour depth and angle of internal friction have a great influence on coefficient of stability.关键词：flood;limit analysis;upper bound theorem;stability of landslide
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- 10
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发布时间：2023-11-14 - 摘要：Abstract:Three kinds of submerged plants－Hydrilla verticillata,Ceratophyllum demersum and ottelia were used and cultivated in domestic sewage. By analyzing removal efficiency of CODcr、TP、NH3-N in domestic sewage , we can research the ablity of them to purify domestic sewage and increase the dissolved oxygen in the water. The results indicated that When the hydraulic retention time was 5 d, the contribution rates of Hydrilla verticillata on the removal of NH3-N,TP,CODcr were 59.84%，35.18%，80.03%; while Ceratophyllum demersum were 40.92%，12.44%，79.93%; ottelia were 22.07%，13.76%，63.70%. Integrated multiple indicators, the best purifying effect is Hydrilla verticillata,the second is Ceratophyllum demersum, the worst is the cauliflower. We prefer Hydrilla verticillata as selected submerged plants in constructed wetlands, and select five days as a stay period.关键词：submerged;domestic sewage;water purification;constructed wetland
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- 2
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发布时间：2023-11-14 - 摘要：Abstract:Three emerged plants－Iris pseudacorus, Cyperus alternifolius And Cyperus papyrus were collected and cultivated with no soil to study their ability of removing main pollutants from domestic wastewater and their stress physiological reactions., as well as analyze the influence to purification effect and tolerance ability of plants in the different concentration domestic sewage. The results showed that the test plants grew well. When the hydraulic retention time was 7 d, the contribution rates of Cyperus alternifolius on the removal of NH3-N,TP,CODcr were 47.25%,32.06%,49.00%; while Iris pseudacorus were 52.00%,32.25%,46.67%; Cyperus papyrus were 48.94%, 15.88% ,51.17%. The quality of wastewater was improved significantly after the treatment, which indicats that these three emerged plants applied to constructed wetland are feasible.关键词：wetland;emerged plant;domestic wastewater;removal rate;stress physiological reactions
- 1576
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- 2
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发布时间：2023-11-14 - 摘要：Abstract:Performance of UF-NF for treatment of municipal wastewater was investigated. The removal efficiency for COD,TP, NH3-N,TDS,was 81%,90%,91%,91%, respectively; The effluent is partial acid(pH 5-6.5) and need to take certain measures to neutral pH.. The results showed that the very high quality of effluent water was obtained. The reclaimed water could be reused either directly or indirectly for municipal or industrial purposes,and even can be used as drinking water sources.
- 2019
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- 2
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发布时间：2023-11-14 - 摘要：Abstract:The traditional methods of measuring the porosity use mainly experimental methods, their accuracy cannot be guaranteed, the reproducibility is poor, and which may cause damage to the material.In this paper, based on the correlations of the elastic and porosity,the nondestructive porosity measurement of tissue engineering scaffold is researched.Ultrasonic vibrometry technology and FEM are be used to simulate that ultrasound excites material to produce acoustic response.As a result,the relationship between the elasticity modulus and porosity is acquired.At the same time,we find when porosity is certain,pore distribution is different,the centroid skewing will affect the natural frequencies,which can’t guarantee the effective young's modulus's oneness. And the influence of centroid to young's modulus is proved:porous model overall effect on the effective young's modulus is equivalent to the sum of every single hole's influence to young's modulus.
- 1727
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发布时间：2023-11-14 - 摘要：Abstract:This paper proposed a novel method based on the inherent epipolar geometry relationship between different views to generate the spatial side information of distributed multi-view video coding system. In this process, the accuracy of the epipolar geometry directly impacts motion search range and the quality of side information. To obtain a more accurate epipolar geometry, we proposed an optimization algorithm based on image registration. It improves the matching accuracy by optimal adjusting the coordinate of feature points and removal of part of feature points with low correlation. Using the epipolar geometry relationship by our algorithm to compute the spatial side information of distributed multi-view video coding system, and test the performance of it. The experiment results show that:By our algorithm,the PSNR of side information increased by more than 2dB through motion search on the epipolar line. When expanding the vertical motion search range, we can get the the similar reconstruction quality with ten to twenty percent of complexity of the original’s. Meanwhile, the rate-distortion performance of the proposed system gain 0.2 ~ 0.7dB compared with the MCII algorithm under the same conditions.关键词：distributed multi-view video coding;epipolar geometry;image registration;feature points optimization;spatial side information
- 1552
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发布时间：2023-11-14 - 摘要：Abstract:A position method was studied under the condition of only three visible satellites in this paper in order to improve the positioning performance of assisted Global Navigation Satellite System (ANGSS) and to implement effective positioning with imperfect positioning condition. In the research, AGNSS positioning structure was used to capture satellite more quickly and to provide assisted data. The positioning results were calculated by the combination of double-observation data, then the influence of no overlapped satellites, overlapped satellites and the length of double-observation interval time on the dilution of precision (DOP), positioning performance and confidence were analyzed. The positioning results were showed that the positioning performance was getting better and better with the interval of two observations increasing. When the length of interval time was 2min, the positioning accuracy was up to 2.22m under the condition of no overlapped satellites, and the accuracy was 3.21m under overlapped one satellite, and the accuracy was 16.76m under overlapped two satellites, and the accuracy was 38.72m. The positioning accuracy could meet the needs of the users for position, and the AGNSS positioning performance was enhanced.关键词：AGNSS;DOP;positioning performance;enhance
- 1521
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发布时间：2023-11-14 - 摘要：Abstract: In this paper, we discuss Frame Rate up Conversion .Many algorithm for frame rate up conversion have been presented, but none of them make full use of the information of image to estimate the motion vector of insert block. In order to resolve the problems of error motion estimation duo to spurious temporal symmetry for frame rate up conversion and decrease block artifacts，this paper proposes a novel video frame rate up-conversion algorithm based on verification block and verification frame. We calculate the bidirectional matching ratio of the block in inter-frame，then verify the results of the motion estimation by verification frame and verification block and get a more accurate motion estimation. Finally, the motion vector smoothing and adaptive overlap block motion compensation are execute to get interpolation frame. Experimental results show that the proposed algorithm provides better subjective and objective quality, when compared to the conventional algorithm.关键词：frame rate up-conversion;bilateral motion compensation;overlapped block motion compensation
- 1983
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- 0
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发布时间：2023-11-14 - 摘要：Abstract:The equity and efficiency of the initial GDP-E slot allocation was investigated in order to make more scientifically use of the airport slot resources. By introducing equity constraint parameter based on OPTIFLOW assignment model, a initial GDP-E slot allocation optimization model was established, which could reach balance between equality and efficiency. Meanwhile, a equity evaluation index of the slot allocation was presented. Because the result of the slot allocation was a special sequence, the model was solved by genetic algorithm using the partially patched crossover(PMX) operator. The simulation results showed the effectiveness of the slot allocation model, which not only improved efficiency by 22.5 percent than the ration by schedule(RBS) algorithm, but also balanced the delay cost between airlines, and by setting the equity constraint parameter within 0.05 and 0.2, the balance between equality and efficiency could be adjusted efficiently.关键词：ground delay program;equity;slot allocation;genetic algorithms
- 1753
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发布时间：2023-11-14 - 摘要：Abstract:Aimed at analyzing users trajectory similarity on LBSN, the check-in points were hierarchical clustered, and the similarity of users’ track on each layer was calculated, then the geospatial similarity of the users’ behaviors was obtained, the Adaptive-Density-Clustering-Based User Trajectory Similarity Double Weighted Model was proposed. Specific to the distribution of users’ check-in points, the Clustering-Area-Radius-Based Adaptive Density Clustering Algorithm was proposed, the check-in points were clustered and the layered clustering areas which with certain area radius were obtained. The User Trajectory Similarity Double Weighted Model was put forward when calculating the users’ similarity: different weights of various levels and different weights of different areas in the same level. Then the similarity of users’ track on each layer was calculated based on the hierarchical clustering area. And due to different characterization ability for users’ similarity degree in the different areas, the similarity in specific level was calculated by the different weight. After that, the geospatial similarity of the users’ behaviors was obtained by overlapping the different scale user similarity value with different weighted. The simulation results demonstrate that this method can effectively analyze the users’ similarity of the track, and has higher accuracy.关键词：LOCATION BASED SERVICES;SOCIAL NETWORKING;check-in data;adaptive density clustering algorithm;trajectory similarity
- 2358
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发布时间：2023-11-14 - 摘要：Abstract: In this paper, a color image enhancement algorithm combined DCT transform and nonsubsampled contourlet transform was proposed. Since the difference of subband characteristics of nonsubsampled contourlet transform, different enhancement algorithms were proposed to enhance the low frequency subband and the high frequency subbands respectively. In order to fix the color shift, color restoration was applied to enhanced image. The simple sharpening was processed. From the result, the whole contrast was improved, while preserving more details and fidelity. It was better than DCT transform enhancement and curvelet transform enhancement from both visual and objective standard.关键词：DCT transform;curvelet transform;nonsubsampled contourlet transform;color image enhancement algorithm
- 1883
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发布时间：2023-11-14 - 摘要：Abstract:Traditional clustering method had obvious errors in processing immunohistochemical digital image. In order to improve the accuracy of cells classification and counting, a new immunohistochemical digital image processing method was proposed in this paper, which normalized the image in LAB color space, and then convert it to HSV color space. This method uses the maximum between-cluster variation weighted clustering to classify different types of cells in the image, and uses morphological methods to segment and count the cells of different types respectively. Experiment demonstrates that the method can use the color information effectively, on the premise of maintaining the high noise tolerant capability, the method can use the color information effectively to realize the classification of cells in immunohistochemical digital image, and accomplish the segmentation and count accurately.关键词：immunohistochemical digital image processing;maximum between-cluster variation clustering;weighted clustering
- 1725
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发布时间：2023-11-14 - 摘要：Abstract:This paper proposed a novel method for automatic haze removal. The algorithm made the best use of advantages of both NIR and visible light image. First, it estimated the haze density distribution by using dark channel prior. Based on this, then, calculated the normalized luminance distribution coefficient of dark channel image via bilateral filtering. Finally, fusing near-infrared(NIR) and visible light image together. Experiments show that the algorithm can effectively improve the quality of the degraded image and it has broad application prospects.关键词：near-infrared;image fusion;image dehazing;filtering
- 2914
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发布时间：2023-11-14 - 摘要：Abstract:In order to solve the problem of serious geometric distortion in large curvature projection system, a twice geometric calibration algorithm was proposed. The geometric calibration of images’ vertex coordinates and texture coordinates were adjusted in chronological order. The description of the algorithm and its program implementation based on Visual C++ and OpenGL were presented. Besides, contrast experiments were carried out with a three-projector display system. Experimental results showed that the twice image calibration algorithm could achieve a good image alignment and have a better expansibility and application value.
- 1837
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发布时间：2023-11-14 - 摘要：Abstract:In wideband cognitive radio (CR) networks, spectrum sensing entails the technical challenges that high sampling rates are required for processing wideband signals, and the performance of spectrum sensing can be easily compromised by primary user emulation attack (PUEA). To overcome these challenges, a collaborated compressive spectrum sensing algorithm using iterative attack detection is developed in this paper. Compressive sensing is performed at each CR to reduce the sampling rates and the complexity of signal acquisition. The fusion center collects the sensing reports from CRs to estimate primary user’s transmit power and pathloss exponent, and monitors the measurement residual which is utilized in iterative attack detection to detect abnormal sensing reports compromised by PUEA. After removing abnormal sensing reports, collaborated spectrum sensing accuracy can be improved. Simulations show the proposed algorithm is robust to PUEA, and achieves effective and reliable spectrum sensing at sub-Nyquist sampling rate.关键词：cognitive radio;collaborative spectrum sensing;primary user emulation attack;compressive sensing
- 1922
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发布时间：2023-11-14 - 摘要：Abstract: The tracking results are often disappointed with poor accuracy and robustness because only single cue is adopted in the traditional particle filter algorithm. To solve this problem, a particle filter tracking algorithm based on fuzzy logic fusion of color and LBP is proposed in this paper, which improves the accuracy of target tracking. Firstly, two features, namely, local binary patterns and weighted color histogram features are calculated. Then, the two features are fused adaptively using the fuzzy logic method. Experimental results show that the proposed tracking method has a good tracking performance in a good deal of challenging environment and the results are accurate and robust.关键词：particle filter;LBP;weighted color histogram;Fuzzy logic;multi-cue fusion
- 1740
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发布时间：2023-11-14 - 摘要：Abstract:In order to solve the power supply problem in remote areas, isolated microgrid scheme with multi-energy complementary was proposed, and optimal disposition result was obtained. In terms of the isolated microgrid scheme, based on the consideration of economic, environment, reliability, economic disposition model was built, and simulated by HOMER with load following control strategy to optimize output of distributed energy, thus getting the optimal result. The effectiveness of the proposed method was verified by calculation results of a test system and influence on result was analyzed when parameters changed. Furthermore, compared with the scheme based on the proposed critical economic distance, the method in this paper was demonstrated reasonably.关键词：remote areas;isolated microgrid;energy optimization;multi-energy complementary;critical economic distance
- 1676
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发布时间：2023-11-14 - 摘要：Abstract:Transformer failure was divided into four types of failure process: thermal, electrical, mechanical and random. With the hypothesis of independence, service life model under combined stresses was established. In the model, the impact of overload was considered for thermal life, and for electrical and mechanical life, relative aging rate was introduced to consider the variability of various parameters. Results showed there was a probability of 77.7% that the failure would occur between 20 to 30 years, and the failure rate was consistent with the median and late periods of bathtub curve. The failures in the first 15 years were attributed to random failures, and after that a rapid growth trend appeared in which electrical or mechanical failure played a dominant role, but the role of thermal fault was less obvious. Parameter sensitivity analysis showed that the sensitivity of electrical stress was greater than thermal or mechanical stress, which indicated the differences in ambient temperature might be less important than the differences in operating voltage for transformer life.关键词：transformers;service life;failure
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发布时间：2023-11-14 - 摘要：Abstract:Different types of wind turbine generator generate different noises in normal condition. A comparison of noises from local spot by means of modern acoustic measurement is carried out between 200W concentrated wind energy turbine and ordinary wind energy turbine, and conclusion is that the noises from the concentrated wind energy turbine are lower than that from the ordinary one. Besides, the main noises are from turbine blades, and increase with the increase of wind speed on both turbines.关键词：Concentrated wind energy;Wind turbine generator;Noise;Measurement and analysis
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发布时间：2023-11-14
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