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The Conversion of Non-Dispersed Polymers into Low-Potassium Anti-Collapse Drilling Fluids
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作者 Hao Hu Jian Guan +2 位作者 Shanfa Tang Jialuo Rong Yuanpeng Cheng 《Fluid Dynamics & Materials Processing》 EI 2024年第2期325-335,共11页
Different drillingfluid systems are designed according to mineral composition,lithology and wellbore stability of different strata.In the present study,the conversion of a non-dispersed polymer drillingfluid into a low ... Different drillingfluid systems are designed according to mineral composition,lithology and wellbore stability of different strata.In the present study,the conversion of a non-dispersed polymer drillingfluid into a low potas-sium anti-collapsing drillingfluid is investigated.Since the two drillingfluids belong to completely different types,the key to this conversion is represented by new inhibitors,dispersants and water-loss agents by which a non-dispersed drillingfluid can be turned into a dispersed drillingfluid while ensuring wellbore stability and reason-able rheology(carrying sand—inhibiting cuttings dispersion).In particular,the(QYZ-1)inhibitors and(FSJSS-2)dispersants are used.The former can inhibit the hydration expansion capacity of clay,reduce the dynamic shear force and weaken the viscosity;the latter can improve the sealing effect and reduce thefiltrate loss.The results have shown that after adding a reasonable proportion of these substances(QYZ-1:FSJSS-2)to the non-dispersed polymer drillingfluid,while the apparent viscosity,plastic viscosity,structural viscosity andfluidity index under-went almost negligible changes,the dynamic plastic ratio increased,and thefiltration loss decreased significantly,thereby indicating good compatibility.According to the tests(conducted in the Leijia area),the density was 1.293 g/cm3,and after standing for 24 h,the SF(static settlement factor)was 0.51.Moreover,thefiltration loss was reduced to 4.0 mL,the rolling recovery rate reached 96.92%,with excellent plugging and anti-collapse performances. 展开更多
关键词 Non-dispersed polymer drilling fluid low potassium anti-collapsing drilling fluid drilling fluid conversion drilling fluid reuse filter vector
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Subband adaptive filter with variable reusing order of coefficient vectors
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作者 倪锦根 《Journal of Beijing Institute of Technology》 EI CAS 2015年第3期375-380,共6页
To increase the convergence rate of the improved normalized subband adaptive filter,a simple but effective method is presented to change the reusing order of coefficient vectors of the adaptive filter. At the beginnin... To increase the convergence rate of the improved normalized subband adaptive filter,a simple but effective method is presented to change the reusing order of coefficient vectors of the adaptive filter. At the beginning of adaptation the algorithmjust uses its current coefficient vector to update the adaptive filter to maintain fast convergence rate,while in steady state it employs several most recent coefficient vectors to update the adaptive filter to reduce misalignment. Simulation results showthat the proposed algorithmcan obtain both fast convergence rate and small steady-state misalignment. 展开更多
关键词 adaptive filtering subband adaptive filter reusing coefficient vector misalignment
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Hepatic CT image retrieval based on the combination of Gabor filters and support vector machine 被引量:2
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作者 蒋历军 罗永兴 +1 位作者 赵俊 庄天戈 《Chinese Optics Letters》 SCIE EI CAS CSCD 2008年第7期495-498,共4页
Content-based image retrieval has been an active area of research for more than ten years. Gabor schemes and support vector machine (SVM) method have been proven effective in image representation and clas-sification... Content-based image retrieval has been an active area of research for more than ten years. Gabor schemes and support vector machine (SVM) method have been proven effective in image representation and clas-sification. In this paper, we propose a retrieval scheme based on Gabor filters and SVMs for hepatic computed tomography (CT) images query. In our experiments, a batch of hepatic CT images containing several types of CT findings are used for the retrieval test. Precision comparison between our scheme and existing methods is presented. 展开更多
关键词 CT Hepatic CT image retrieval based on the combination of Gabor filters and support vector machine
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Electrically-manipulable electron-momentum filter based on antiparallel asymmetric doubleδ-magnetic-barrier semiconductor microstructure
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作者 Ge Tang Ying-Jie Qin +1 位作者 Shi-Shi Xie Meng-Hao Sun 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第10期530-533,共4页
We theoretically investigate the wave-vector filtering(WVF)effect for electrons in an antiparallel asymmetric doubleδ-magnetic-barrier microstructure under a bias,which can be fabricated experimentally by patterning ... We theoretically investigate the wave-vector filtering(WVF)effect for electrons in an antiparallel asymmetric doubleδ-magnetic-barrier microstructure under a bias,which can be fabricated experimentally by patterning two asymmetric ferromagnetic(FM)stripes on the top and the bottom of GaAs/AlxGa1−xAs heterostructure,respectively.It is found that an appreciable WVF effect appears because of an essentially two-dimensional(2D)process for electrons across this microstructure.WVF effect is found to be sensitive to the applied bias.WVF efficiency can be tuned by changing bias,which may lead to an electrically-controllable momentum filter for nanoelectronics device applications. 展开更多
关键词 magnetic microstructure BIAS wave vector filtering(WVF)effect electrically-tunable momentum filter
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A NEW METHOD OF CHANNEL FRICTION INVERSION BASED ON KALMAN FILTER WITH UNKNOWN PARAMETER VECTOR
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作者 CHENG Wei-ping MAO Gen-hai LIU Guo-hua 《Journal of Hydrodynamics》 SCIE EI CSCD 2005年第6期693-698,共6页
Channel friction is an important parameter in hydraulic analysis. A channel friction parameter inversion method based on Kalman Filter with unknown parameter vector is proposed. Numerical simulations indicate that whe... Channel friction is an important parameter in hydraulic analysis. A channel friction parameter inversion method based on Kalman Filter with unknown parameter vector is proposed. Numerical simulations indicate that when the number of monitoring stations exceeds a critical value, the so lution is hardly affected. In addition, Kalman Filter with unknown parameter vector is effective only at unsteady state. For the nonlinear equations, computations of sensitivity matrices are time-costly. Two simplified measures can reduce computing time, but not influence the results. One is to reduce sensitivity matrix analysis time, the other is to substitute for sensitivity matrix. 展开更多
关键词 CHANNEL INVERSION Kalman Filter with unknown parameter vector FRICTION
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Side Information Generation Based on Hierarchical Motion Estimation in Distributed Video Coding 被引量:4
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作者 刘荣科 岳志 陈长汶 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2009年第2期167-173,共7页
The side information quality has an immense effect on the compression efficiency of the distributed video coding (DVC) sys- tem. This article, based on the hierarchical motion estimation (HME), proposes a new side inf... The side information quality has an immense effect on the compression efficiency of the distributed video coding (DVC) sys- tem. This article, based on the hierarchical motion estimation (HME), proposes a new side information generation algorithm which is integrated into DVC system. First, forward motion estimation (FME) and bidirectional motion estimation (BME) on the basis of variable block size HME algorithm are used to acquire relatively accurate motion vectors. Second, a motion vector filter (MVF) is i... 展开更多
关键词 communication technology video signal processing hierarchical motion estimation side information motion vector filter frame interpolation
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Optimizing CMT performance by joint predictions of bandwidth and RTT
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作者 Li Wen Wang Wenbo +1 位作者 Jing Xiaojun Liu Wen 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2015年第4期81-91,共11页
CMT uses the stream control transmission protocol's(SCTPs) multihoming feature to distribute data across multiple end-to-end paths in a multihomed SCTP association. As the disparity of multipaths, it is facing a gr... CMT uses the stream control transmission protocol's(SCTPs) multihoming feature to distribute data across multiple end-to-end paths in a multihomed SCTP association. As the disparity of multipaths, it is facing a great challenge to solve the disorder of the received data packets. To lighten the reordering degree and then to improve the throughput performance, we need to estimate the real-time paths' bandwidth and round trip time(RTT) as exactly as possible. In this paper, we use the extended vector(ext-vec) Kalman filter(KF) to predict the available bandwidth and RTT of each path simultaneously. Based on this, we propose a predictive path selection algorithm for CMT in SCTP. To simulate and compare the algorithms' performance, two kinds of scenarios, bandwidth sensitive scenario and time and bandwidth sensitive scenario, are built and NS-2 is used. The simulation results show that the path selection algorithm can lessen the data packets disordering by correctly predicting each path's bandwidth and RTT in real time. Comparing the existing algorithms, the algorithm can converge more quickly and can improve the system total throughput in a certain extent in bandwidth sensitive scenario. To time and bandwidth sensitive scenario, it can greatly improve the convergence speed and total throughput. 展开更多
关键词 CMT SCTP extended vector Kalman filter RTT THROUGHPUT
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Improved switching based filter for protecting thin lines of color images
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作者 Chang-cheng WU Chun-yu ZHAO Da-yue CHEN 《Journal of Zhejiang University-Science C(Computers and Electronics)》 SCIE EI 2010年第1期36-44,共9页
The classical vector median filter (VMF) has been widely used to remove impulse noise from color images. However, since the VMF cannot identify thin lines during the denoising process, many thin lines may be removed o... The classical vector median filter (VMF) has been widely used to remove impulse noise from color images. However, since the VMF cannot identify thin lines during the denoising process, many thin lines may be removed out as noise. This serious problem can be solved by a newly proposed filter that uses a noise detector to find these thin lines and then keep them unchanged. In this new approach, the noise detection scheme applied on a current processed pixel is realized through counting the close pixels in its eight neighbor positions and the expanded window to see whether the current pixel is corrupted by impulse noise. Based on the previous outputs, our algorithm can increase the performance in detecting and canceling the impulse noise. Extensive ex- periments indicate that this approach can be used to remove the impulse noise from a color image without distorting the useful information. 展开更多
关键词 vector median filter (VMF) Thin lines Impulse noise Color image
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