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Failure mechanisms and destruction characteristics of cemented coal gangue backfill under compression effect of non-uniform load
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作者 FENG Guo-rui GUO Wei +5 位作者 QI Ting-ye LI Zhu CUI Jia-qing WANG Hao-chen CUI Ye-kai MA Jing-kai 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第8期2676-2693,共18页
Backfill mining is one of the most important technical means for controlling strata movement and reducing surface subsidence and environmental damage during exploitation of underground coal resources. Ensuring the sta... Backfill mining is one of the most important technical means for controlling strata movement and reducing surface subsidence and environmental damage during exploitation of underground coal resources. Ensuring the stability of the backfill bodies is the primary prerequisite for maintaining the safety of the backfilling working face, and the loading characteristics of backfill are closely related to the deformation and subsidence of the roof. Elastic thin plate model was used to explore the non-uniform subsidence law of the roof, and then the non-uniform distribution characteristics of backfill bodies’ load were revealed. Through a self-developed non-uniform loading device combined with acoustic emission (AE) and digital image correlation (DIC) monitoring technology, the synergistic dynamic evolution law of the bearing capacity, apparent crack, and internal fracture of cemented coal gangue backfills (CCGBs) under loads with different degrees of non-uniformity was deeply explored. The results showed that: 1) The uniaxial compressive strength (UCS) of CCGB increased and then decreased with an increase in the degree of non-uniformity of load (DNL). About 40% of DNL was the inflection point of DNL-UCS curve and when DNL exceeded 40%, the strength decreased in a cliff-like manner;2) A positive correlation was observed between the AE ringing count and UCS during the loading process of the specimen, which was manifested by a higher AE ringing count of the high-strength specimen. 3) Shear cracks gradually increased and failure mode of specimens gradually changed from “X” type dominated by tension cracks to inverted “Y” type dominated by shear cracks with an increase in DNL, and the crack opening displacement at the peak stress decreased and then increased. The crack opening displacement at 40% of the DNL was the smallest. This was consistent with the judgment of crack size based on the AE b-value, i. e., it showed the typical characteristics of “small b-value-large crack and large b-value-small crack”. The research results are of significance for preventing the instability and failure of backfill. 展开更多
关键词 cemented coal gangue backfill non-uniform load degree of non-uniformity of load failure mode crack opening displacement
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Study of the pressure transient behavior of directional wells considering the effect of non-uniform flux distribution
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作者 Yan-Zhong Liang Bai-Lu Teng Wan-Jing Luo 《Petroleum Science》 SCIE EI CAS CSCD 2024年第3期1765-1779,共15页
During the production,the fluid in the vicinity of the directional well enters the wellbore with different rates,leading to non-uniform flux distribution along the directional well.However,in all existing studies,it i... During the production,the fluid in the vicinity of the directional well enters the wellbore with different rates,leading to non-uniform flux distribution along the directional well.However,in all existing studies,it is oversimplified to a uniform flux distribution,which can result in inaccurate results for field applications.Therefore,this paper proposes a semi-analytical model of a directional well based on the assumption of non-uniform flux distribution.Specifically,the direction well is discretized into a carefully chosen series of linear sources,such that the complex well trajectory can be captured and the nonuniform flux distribution along the wellbore can be considered to model the three-dimensional flow behavior.By using the finite difference method,we can obtain the numerical solutions of the transient flow within the wellbore.With the aid of Green's function method,we can obtain the analytical solutions of the transient flow from the matrix to the wellbore.The complete flow behavior of a directional well is perfectly represented by coupling the above two types of transient flow.Subsequently,on the basis of the proposed model,we conduct a comprehensive analysis of the pressure transient behavior of a directional well.The computation results show that the flux variation along the direction well has a significant effect on pressure responses.In addition,the directional well in an infinite reservoir may exhibit the following flow regimes:wellbore afterflow,transition flow,inclined radial flow,elliptical flow,horizontal linear flow,and horizontal radial flow.The horizontal linear flow can be observed only if the formation thickness is much smaller than the well length.Furthermore,a dip region that appears on the pressure derivative curve indicates the three-dimensional flow behavior near the wellbore. 展开更多
关键词 Directional well Pressure transient behavior Semi-analytical model non-uniform flux
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Effect of non-uniform swelling on coal multiphysics during gas injection: The triangle approach
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作者 Yifan Huang Jishan Liu +2 位作者 Yaoyao Zhao Derek Elsworth Yee-Kwong Leong 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第4期1362-1372,共11页
In current dual porosity/permeability models,there exists a fundamental assumption that the adsorption-induced swelling is distributed uniformly within the representative elementary volume (REV),irrespective of its in... In current dual porosity/permeability models,there exists a fundamental assumption that the adsorption-induced swelling is distributed uniformly within the representative elementary volume (REV),irrespective of its internal structures and transient processes.However,both internal structures and transient processes can lead to the non-uniform swelling.In this study,we hypothesize that the non-uniform swelling is responsible for why coal permeability in experimental measurements is not only controlled by the effective stress but also is affected by the adsorption-induced swelling.We propose a concept of the swelling triangle composed of swelling paths to characterize the evolution of the non-uniform swelling and serve as a core link in coupled multiphysics.A swelling path is determined by a dimensionless volumetric ratio and a dimensionless swelling ratio.Different swelling paths have the same start and end point,and each swelling path represents a unique swelling case.The swelling path as the diagonal of the triangle represents the case of the uniform swelling while that as the two perpendicular boundaries represents the case of the localized swelling.The paths of all intermediate cases populate inside the triangle.The corresponding relations between the swelling path and the response of coal multiphysics are established by a non-uniform swelling coefficient.We define this method as the triangle approach and corresponding models as swelling path-based ones.The proposed concept and models are verified against a long-term experimental measurement of permeability and strains under constant effective stress.Our results demonstrate that during gas injection,coal multiphysics responses have a close dependence on the swelling path,and that in both future experiments and field predictions,this dependence must be considered. 展开更多
关键词 Transient process HETEROGENEITY Swelling triangle Swelling path non-uniform swelling coefficient
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Pressure transient characteristics of non-uniform conductivity fractured wells in viscoelasticity polymer flooding based on oil-water two-phase flow
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作者 Yang Wang Jia Zhang +2 位作者 Shi-Long Yang Ze-Xuan Xu Shi-Qing Cheng 《Petroleum Science》 SCIE EI CAS CSCD 2024年第1期343-351,共9页
Polymer flooding in fractured wells has been extensively applied in oilfields to enhance oil recovery.In contrast to water,polymer solution exhibits non-Newtonian and nonlinear behavior such as effects of shear thinni... Polymer flooding in fractured wells has been extensively applied in oilfields to enhance oil recovery.In contrast to water,polymer solution exhibits non-Newtonian and nonlinear behavior such as effects of shear thinning and shear thickening,polymer convection,diffusion,adsorption retention,inaccessible pore volume and reduced effective permeability.Meanwhile,the flux density and fracture conductivity along the hydraulic fracture are generally non-uniform due to the effects of pressure distribution,formation damage,and proppant breakage.In this paper,we present an oil-water two-phase flow model that captures these complex non-Newtonian and nonlinear behavior,and non-uniform fracture characteristics in fractured polymer flooding.The hydraulic fracture is firstly divided into two parts:high-conductivity fracture near the wellbore and low-conductivity fracture in the far-wellbore section.A hybrid grid system,including perpendicular bisection(PEBI)and Cartesian grid,is applied to discrete the partial differential flow equations,and the local grid refinement method is applied in the near-wellbore region to accurately calculate the pressure distribution and shear rate of polymer solution.The combination of polymer behavior characterizations and numerical flow simulations are applied,resulting in the calculation for the distribution of water saturation,polymer concentration and reservoir pressure.Compared with the polymer flooding well with uniform fracture conductivity,this non-uniform fracture conductivity model exhibits the larger pressure difference,and the shorter bilinear flow period due to the decrease of fracture flow ability in the far-wellbore section.The field case of the fall-off test demonstrates that the proposed method characterizes fracture characteristics more accurately,and yields fracture half-lengths that better match engineering reality,enabling a quantitative segmented characterization of the near-wellbore section with high fracture conductivity and the far-wellbore section with low fracture conductivity.The novelty of this paper is the analysis of pressure performances caused by the fracture dynamics and polymer rheology,as well as an analysis method that derives formation and fracture parameters based on the pressure and its derivative curves. 展开更多
关键词 Polymer flooding Non-Newtonian fluid non-uniform fracture conductivity Two-phase flow Pressure transient analysis
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An improved non-uniform fast Fourier transform method for radio imaging of coronal mass ejections
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作者 Weidan Zhang Bing Wang +3 位作者 Zhao Wu Shuwang Chang Yao Chen Fabao Yan 《Astronomical Techniques and Instruments》 CSCD 2024年第2期117-127,共11页
Radioheliographs can obtain solar images at high temporal and spatial resolution,with a high dynamic range.These are among the most important instruments for studying solar radio bursts,understanding solar eruption ev... Radioheliographs can obtain solar images at high temporal and spatial resolution,with a high dynamic range.These are among the most important instruments for studying solar radio bursts,understanding solar eruption events,and conducting space weather forecasting.This study aims to explore the effective use of radioheliographs for solar observations,specifically for imaging coronal mass ejections(CME),to track their evolution and provide space weather warnings.We have developed an imaging simulation program based on the principle of aperture synthesis imaging,covering the entire data processing flow from antenna configuration to dirty map generation.For grid processing,we propose an improved non-uniform fast Fourier transform(NUFFT)method to provide superior image quality.Using simulated imaging of radio coronal mass ejections,we provide practical recommendations for the performance of radioheliographs.This study provides important support for the validation and calibration of radioheliograph data processing,and is expected to profoundly enhance our understanding of solar activities. 展开更多
关键词 Radio interference GRIDDING IMAGING non-uniform fast Fourier transform
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Assessment of Lubrication Property and Machining Performance of Nanofluid Composite Electrostatic Spraying(NCES)Using Different Types of Vegetable Oils as Base Fluids of External Fluid 被引量:1
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作者 Yu Su Zepeng Chu +2 位作者 Le Gong Bin Wang Zhiqiang Liu 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2023年第4期97-110,共14页
The current study of minimum quantity lubrication(MQL)concentrates on its performance improvement.By contrast with nanofluid MQL and electrostatic atomization(EA),the proposed nanofluid composite electrostatic sprayin... The current study of minimum quantity lubrication(MQL)concentrates on its performance improvement.By contrast with nanofluid MQL and electrostatic atomization(EA),the proposed nanofluid composite electrostatic spraying(NCES)can enhance the performance of MQL more comprehensively.However,it is largely influenced by the base fluid of external fluid.In this paper,the lubrication property and machining performance of NCES with different types of vegetable oils(castor,palm,soybean,rapeseed,and LB2000 oil)as the base fluids of external fluid were compared and evaluated by friction and milling tests under different flow ratios of external and internal fluids.The spraying current and electrowetting angle were tested to analyze the influence of vegetable oil type as the base fluid of external fluid on NCES performances.The friction test results show that relative to NCES with other vegetable oils as the base fluids of external fluid,NCES with LB2000 as the base fluid of external fluid reduced the friction coefficient and wear loss by 9.4%-27.7%and 7.6%-26.5%,respectively.The milling test results display that the milling force and milling temperature for NCES with LB2000 as the base fluid of external fluid were 1.4%-13.2%and 3.6%-11.2%lower than those for NCES with other vegetable oils as the base fluids of external fluid,respectively.When LB2000/multi-walled carbon nanotube(MWCNT)water-based nanofluid was used as the external/internal fluid and the flow ratio of external and internal fluids was 2:1,NCES showed the best milling performance.This study provides theoretical and technical support for the selection of the base fluid of NCES external fluid. 展开更多
关键词 Nanofluid composite electrostatic spraying Lubrication property Machining performance Vegetable oil External fluid
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Robust and Reusable Fuzzy Extractors from Non-Uniform Learning with Errors Problem
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作者 Joo Woo Jonghyun Kim Jong Hwan Park 《Computers, Materials & Continua》 SCIE EI 2023年第1期1985-2003,共19页
Afuzzy extractor can extract an almost uniformrandom string from a noisy source with enough entropy such as biometric data.To reproduce an identical key from repeated readings of biometric data,the fuzzy extractor gen... Afuzzy extractor can extract an almost uniformrandom string from a noisy source with enough entropy such as biometric data.To reproduce an identical key from repeated readings of biometric data,the fuzzy extractor generates a helper data and a random string from biometric data and uses the helper data to reproduce the random string from the second reading.In 2013,Fuller et al.proposed a computational fuzzy extractor based on the learning with errors problem.Their construction,however,can tolerate a sub-linear fraction of errors and has an inefficient decoding algorithm,which causes the reproducing time to increase significantly.In 2016,Canetti et al.proposed a fuzzy extractor with inputs from low-entropy distributions based on a strong primitive,which is called digital locker.However,their construction necessitates an excessive amount of storage space for the helper data,which is stored in authentication server.Based on these observations,we propose a new efficient computational fuzzy extractorwith small size of helper data.Our scheme supports reusability and robustness,which are security notions that must be satisfied in order to use a fuzzy extractor as a secure authentication method in real life.Also,it conceals no information about the biometric data and thanks to the new decoding algorithm can tolerate linear errors.Based on the non-uniform learning with errors problem,we present a formal security proof for the proposed fuzzy extractor.Furthermore,we analyze the performance of our fuzzy extractor scheme and provide parameter sets that meet the security requirements.As a result of our implementation and analysis,we show that our scheme outperforms previous fuzzy extractor schemes in terms of the efficiency of the generation and reproduction algorithms,as well as the size of helper data. 展开更多
关键词 Fuzzy extractor REUSABILITY robustness biometric authentication non-uniform learning with errors
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Effect of steam spraying on a sintering bed on sinter quality and the emission of flue gas pollutants
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作者 QI Yilong WU Hongliang +3 位作者 YU Zhengwei LONG Hongming WU Zhiyong WANG Wen 《Baosteel Technical Research》 CAS 2023年第2期37-46,共10页
The technology for spraying a sintering bed and thus improving sinter quality indicators while reducing the emission of flue gas pollutants has recently become an important research topic.The impacts on sinter quality... The technology for spraying a sintering bed and thus improving sinter quality indicators while reducing the emission of flue gas pollutants has recently become an important research topic.The impacts on sinter quality and emissions when spraying the sintering surface with different amounts and flow rates of steam were investigated in this study.The sinter quality indicators were most effectively improved by spraying 180 g of steam flow continuously at a rate of 0.02 m^(3)/min for 15 min after ignition for 8 min.The optimal effect on emission reduction was obtained by spraying 90 g of steam flow continuously at a rate of 0.01 m^(3)/min for 15 min after ignition for 8 min. 展开更多
关键词 SINTERING steam spraying emission reduction flue gas pollutants
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Radial Basis Approximations Based BEMD for Enhancement of Non-Uniform Illumination Images
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作者 Anchal Tyagi Salem Alelyani +3 位作者 Sapna Katiyar Mohammad Rashid Hussain Rijwan Khan Mohammed Saleh Alsaqer 《Computer Systems Science & Engineering》 SCIE EI 2023年第5期1423-1438,共16页
An image can be degraded due to many environmental factors like foggy or hazy weather,low light conditions,extra light conditions etc.Image captured under the poor light conditions is generally known as non-uniform il... An image can be degraded due to many environmental factors like foggy or hazy weather,low light conditions,extra light conditions etc.Image captured under the poor light conditions is generally known as non-uniform illumination image.Non-uniform illumination hides some important information present in an image during the image capture Also,it degrades the visual quality of image which generates the need for enhancement of such images.Various techniques have been present in literature for the enhancement of such type of images.In this paper,a novel architecture has been proposed for enhancement of poor illumination images which uses radial basis approximations based BEMD(Bi-dimensional Empirical Mode Decomposition).The enhancement algorithm is applied on intensity and saturation components of image.Firstly,intensity component has been decomposed into various bi-dimensional intrinsic mode function and residue by using sifting algorithm.Secondly,some linear transformations techniques have been applied on various bidimensional intrinsic modes obtained and residue and further on joining the transformed modes with residue,enhanced intensity component is obtained.Saturation part of an image is then enhanced in accordance to the enhanced intensity component.Final enhanced image can be obtained by joining the hue,enhanced intensity and enhanced saturation parts of the given image.The proposed algorithm will not only give the visual pleasant image but maintains the naturalness of image also. 展开更多
关键词 non-uniform illumination BEMD intrinsic modes radial basis approximation linear transformation
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Image Non-Uniformity Correction in 3T Gd-EOB-DTPA-Enhanced Magnetic Resonance Imaging: Comparison among Different Software Versions
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作者 Hirofumi Hata Yusuke Inoue +5 位作者 Keiji Matsunaga Kaoru Fujii Toshio Tamiya Ai Nakajima Yuki Takato Kazuki Hashizume 《Open Journal of Medical Imaging》 2023年第3期114-126,共13页
Background: Non-uniformity in signal intensity occurs commonly in magnetic resonance (MR) imaging, which may pose substantial problems when using a 3T scanner. Therefore, image non-uniformity correction is usually app... Background: Non-uniformity in signal intensity occurs commonly in magnetic resonance (MR) imaging, which may pose substantial problems when using a 3T scanner. Therefore, image non-uniformity correction is usually applied. Purpose: To compare the correction effects of the phased-array uniformity enhancement (PURE), a calibration-based image non-uniformity correction method, among three different software versions in 3T Gd-EOB-DTPA-enhanced MR imaging. Material and Methods: Hepatobiliary-phase images of a total of 120 patients who underwent Gd-EOB-DTPA-enhanced MR imaging on the same 3T scanner were analyzed retrospectively. Forty patients each were examined using three software versions (DV25, DV25.1, and DV26). The effects of PURE were compared by visual assessment, histogram analysis of liver signal intensity, evaluation of the spatial distribution of correction effects, and evaluation of quantitative indices of liver parenchymal enhancement. Results: The visual assessment indicated the highest uniformity of PURE-corrected images for DV26, followed by DV25 and DV25.1. Histogram analysis of corrected images demonstrated significantly larger variations in liver signal for DV25.1 than for the other two versions. Although PURE caused a relative increase in pixel values for central and lateral regions, such effects were weaker for DV25.1 than for the other two versions. In the evaluation of quantitative indices of liver parenchymal enhancement, the liver-to-muscle ratio (LMR) was significantly higher for the corrected images than for the uncorrected images, but the liver-to-spleen ratio (LSR) showed no significant differences. For corrected images, the LMR was significantly higher for DV25 and DV26 than for DV25.1, but the LSR showed no significant differences among the three versions. Conclusion: There were differences in the effects of PURE among the three software versions in 3T Gd-EOB-DTPA-enhanced MR imaging. Even if the non-uniformity correction method has the same brand name, correction effects may differ depending on the software version, and these differences may affect visual and quantitative evaluations. 展开更多
关键词 GD-EOB-DTPA non-uniformity Correction 3 Tesla Software Version Image Contrast
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激光复合冷喷涂技术研究进展 被引量:1
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作者 李波 胡耀峰 +3 位作者 田凯 姜家涛 吴丽娟 姚建华 《中国材料进展》 CAS CSCD 北大核心 2024年第2期115-123,共9页
冷喷涂是一种基于材料高速撞击产生剧烈塑性变形实现结合的沉积方法,具备加工温度低、沉积效率高、热影响小等优势,已在增材制造、工业关键零部件的修复再制造等领域展现出巨大潜力。冷喷涂复合制造技术是一种新兴技术,其中激光复合冷... 冷喷涂是一种基于材料高速撞击产生剧烈塑性变形实现结合的沉积方法,具备加工温度低、沉积效率高、热影响小等优势,已在增材制造、工业关键零部件的修复再制造等领域展现出巨大潜力。冷喷涂复合制造技术是一种新兴技术,其中激光复合冷喷涂是一个重要的方向,近年来得到了越来越多的关注。对激光复合冷喷涂技术研究进展进行回顾和总结,对激光预处理、激光同步复合和激光后处理3种复合方式进行重点阐释。针对每种复合方式,分别从复合原理、复合优势及复合效果3个方面进行总结,对比激光复合冷喷涂技术与单一技术在沉积层微观组织以及性能等方面的差异。通过对激光复合冷喷涂技术最新进展的全面总结和归纳,将为进一步推动激光复合冷喷涂技术的研究和应用提供指导和参考。 展开更多
关键词 冷喷涂 复合 激光技术 微观组织 性能
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基于轻量化PointNet网络的林果园喷雾作业靶标实时识别方法 被引量:1
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作者 刘慧 杜志鹏 +2 位作者 杨锋 张钰 沈跃 《农业工程学报》 EI CAS CSCD 北大核心 2024年第8期144-151,共8页
为了进一步提高喷雾机器人靶标检测的精准性、实时性和应用部署的实用性,该研究提出一种基于轻量化PointNet网络的林果园喷雾作业靶标实时识别方法。首先通过区域提取降采样、地面分割和改进DBSCAN聚类等点云预处理方法提取原始点云中... 为了进一步提高喷雾机器人靶标检测的精准性、实时性和应用部署的实用性,该研究提出一种基于轻量化PointNet网络的林果园喷雾作业靶标实时识别方法。首先通过区域提取降采样、地面分割和改进DBSCAN聚类等点云预处理方法提取原始点云中的靶标;然后通过移动最小二乘上采样将靶标点云转化为满足点云识别网络输入要求的点云数据;最终通过在PointNet网络中引入残差模块和改进循环剪枝算法轻量化PointNet网络,完成林果树靶标的实时识别。试验结果表明,在ModelNet40数据集上,轻量化PointNet网络可达89.7%的准确率;在实际苗圃环境的试验中,该研究方法对靶标的识别准确率可达92.49%,同时误识率与拒识率分别为13.4%和6.47%,相较PointNet网络识别准确率提升了4.38个百分点,误识率和拒识率分别降低了7.2和4.07个百分点;轻量化PointNet网络识别准确率仅比PointNet++网络低1.14个百分点,误识率和拒识率分别高了0.9和1.12个百分点。但是轻量化PointNet网络的模型参数量较PointNet网络和PointNet++网络的模型参数量显著减少,仅为PointNet网络的11.5%,PointNet++网络的27.02%;运算量相较PointNet网络、PointNet++网络分别减少13.3和76.79个百分点。该研究提出的轻量化PointNet网络具有较高的实时性、精确性和鲁棒性,能够满足林果园喷雾作业的靶标识别需求,可为林果园喷雾作业靶标实时识别提供参考。 展开更多
关键词 喷雾 机器人 林果园 点云预处理 轻量化PointNet网络 循环剪枝
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钢纤维喷射砂浆力学性能与流动度多因素正交试验分析 被引量:1
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作者 潘慧敏 张昊 +2 位作者 李梦谊 谢少康 赵庆新 《硅酸盐通报》 CAS 北大核心 2024年第2期466-477,共12页
为探究基体因素对钢纤维喷射砂浆力学性能和流动度的影响,基于正交试验方法对砂浆试件进行了力学性能和流动度测试。结果表明:砂胶比(A)对劈裂抗拉强度的影响较大,对7 d抗压强度有一定的影响,对后期抗折强度影响特别显著;钢纤维掺量(B)... 为探究基体因素对钢纤维喷射砂浆力学性能和流动度的影响,基于正交试验方法对砂浆试件进行了力学性能和流动度测试。结果表明:砂胶比(A)对劈裂抗拉强度的影响较大,对7 d抗压强度有一定的影响,对后期抗折强度影响特别显著;钢纤维掺量(B)对劈裂抗拉强度、前期抗折强度和前中期抗压强度的影响分别为特别显著、显著和不显著;速凝剂掺量(C)对7 d前抗压强度、中后期劈裂抗拉强度影响显著;粉煤灰掺量(D)仅对后期抗压强度的影响显著;前述四种因素掺量对流动度的影响均不显著。由层次分析法得到对抗压强度、抗折强度、劈裂抗拉强度和流动度改善效果最佳的配合比分别为A1B3C3D1、A3B3C1D2、A3B3C3D1、A2B1C1D3,由功效系数法得到综合最佳配合比为A2B3C1D2。钢纤维在基体中起桥接与锚固加强的作用,速凝剂在水化过程中消耗大量的Ca(OH)_(2)并生成钙矾石,促使喷射砂浆早期强度迅速提升。 展开更多
关键词 喷射砂浆 钢纤维 正交试验 功效系数法 微观分析
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微米级类球形介孔材料用于乙烯聚合催化剂 被引量:1
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作者 亢宇 吕新平 刘红梅 《石油化工》 CAS CSCD 北大核心 2024年第3期339-346,共8页
采用2-(4-氯磺酰苯基)乙基三甲氧基硅烷对类球形介孔材料进行疏水处理,制备了疏水性类球形介孔材料,将其作为载体,通过气流式喷雾干燥技术制备了聚乙烯催化剂。对疏水处理前后的类球形介孔材料进行了XRD、N2吸附-脱附、TEM、SEM表征,考... 采用2-(4-氯磺酰苯基)乙基三甲氧基硅烷对类球形介孔材料进行疏水处理,制备了疏水性类球形介孔材料,将其作为载体,通过气流式喷雾干燥技术制备了聚乙烯催化剂。对疏水处理前后的类球形介孔材料进行了XRD、N2吸附-脱附、TEM、SEM表征,考察了气流式喷雾干燥过程中载气流量和浆料浓度对聚乙烯催化剂的影响,并评价了催化剂的乙烯聚合性能。实验结果表明,类球形介孔材料在疏水处理后孔结构和微观结构稳定;最佳喷雾干燥条件为喷雾干燥器进、出风口温度分别为140,105℃,载气流量为30 L/s,浆料浓度为30%(w);在最佳喷雾干燥条件下制备的催化剂用于乙烯聚合时,催化活性为28000 g/g,远高于工业用TS-610硅胶制备的催化剂的活性(9000 g/g),反应得到的聚合物性能也优于TS-610硅胶制备的催化剂得到的聚乙烯粉料。 展开更多
关键词 类球形介孔材料 疏水改性 气流式喷雾干燥 乙烯聚合
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余热回收喷淋塔喷淋优化研究 被引量:1
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作者 时国华 潘春江 +3 位作者 赵玺灵 张世钢 付林 李增群 《流体机械》 CSCD 北大核心 2024年第1期48-55,共8页
针对喷淋塔内烟气偏流影响烟气与下落液滴群热质交换的问题,构建并通过试验验证了喷淋塔内气液流动及余热回收理论模型,基于液滴自调整效应,运用CFD技术模拟研究4种喷淋层布置方式下余热回收喷淋塔的性能,获得了最佳喷淋方案及其喷淋参... 针对喷淋塔内烟气偏流影响烟气与下落液滴群热质交换的问题,构建并通过试验验证了喷淋塔内气液流动及余热回收理论模型,基于液滴自调整效应,运用CFD技术模拟研究4种喷淋层布置方式下余热回收喷淋塔的性能,获得了最佳喷淋方案及其喷淋参数。结果表明:与常规单层均匀喷淋方式相比,增设半层喷淋能够有效提升塔内烟气流动均匀性,塔内烟气均匀度由1降至0.3左右,喷淋塔全热交换效率最多可提升20%;半层喷淋最佳布置位置在烟气入口中心线上3 m处;综合考虑余热回收效果和运行成本,最佳喷淋液滴直径为0.6~0.8 mm,最佳水气比为5 kg/kg。构建的喷淋塔内烟气余热回收模型与提出的喷淋优化方法可为其特性分析、工艺优化、参数设计及运行提供理论指导。 展开更多
关键词 余热回收 喷淋塔 流场均匀性 数值模拟
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连栋温室分段变距喷雾机器人设计与试验
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作者 李天华 董广胜 +3 位作者 姚玉康 张观山 王德伦 施国英 《农业机械学报》 EI CAS CSCD 北大核心 2024年第2期170-179,共10页
针对国内连栋温室缺乏植保喷雾机、机械走直定位与换轨转向精度低等问题,设计了一种连栋温室分段变距喷雾机器人,在实现无人化喷药的同时提高作业精度。为满足连栋温室机械作业路轨结合、精准切换的要求,提出一种通用型移动底盘,并确定... 针对国内连栋温室缺乏植保喷雾机、机械走直定位与换轨转向精度低等问题,设计了一种连栋温室分段变距喷雾机器人,在实现无人化喷药的同时提高作业精度。为满足连栋温室机械作业路轨结合、精准切换的要求,提出一种通用型移动底盘,并确定其关键设计参数;为减少底盘上下轨时的偏移量,设计轨上矫正装置,通过分析计算及试验验证,确定其安装余量为4 mm;针对底盘对轨误差大的问题,提出一种二维码融合陀螺仪及光电传感器双向垂直寻迹的路面关键点定位与转向控制方法。设计分段变距喷雾装置,提出一种丝杆滑台驱动的喷杆变距方案,分析校验其驱动参数以满足工作要求;基于滚针轴承设计喷杆辅助防抖装置,减小因喷杆剧烈抖动带来的滑台与喷杆损伤。开发底盘运动及分段变距喷雾控制系统,实现喷雾机器人在连栋温室内的全程自动化作业。最后,对样机进行底盘性能与喷雾效果试验。底盘作业时直线行走与对轨误差平均值分别为4.8、5.8 mm,满足控制精度要求;避障距离为34 cm,满足安全性要求;防抖装置的安装使喷杆行进方向的抖动量从-1°~1.3°降低到±0.4°内,喷头方向的抖动量从±0.5°降低到±0.3°内,防抖效果显著;分段变距喷雾作业后,盛果期番茄叶片正面雾滴沉积量为1.76μL/cm^(2),反面沉积量为0.2μL/cm^(2),雾滴体积中径在100~180μm之间,满足作业要求。 展开更多
关键词 连栋温室 喷雾机器人 扫码定位 分段喷雾 变距喷雾
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红肉火龙果粉的发泡微波冷冻干燥制备与质量评价 被引量:1
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作者 王维 王占冬 +3 位作者 于佳慧 林润泽 张朔 张大为 《农业工程学报》 EI CAS CSCD 北大核心 2024年第6期79-89,共11页
制备浆果粉末产品是延长其货架期的有效手段。为降低干燥过程能耗和保留产品营养成分,该研究以平均含水率(87.03±1.26)%的新鲜红肉火龙果果浆为原料,采用冷冻干燥和喷雾干燥两种方法制备了火龙果粉末。以残余湿含量、色泽和典型生... 制备浆果粉末产品是延长其货架期的有效手段。为降低干燥过程能耗和保留产品营养成分,该研究以平均含水率(87.03±1.26)%的新鲜红肉火龙果果浆为原料,采用冷冻干燥和喷雾干燥两种方法制备了火龙果粉末。以残余湿含量、色泽和典型生物活性成分甜菜红素、芦丁和总酚保留率为指标对产品质量进行了评价。用质量比为3%(w/w)的分离乳清蛋白和2.5%(w/w)的果胶为添加剂制备了未发泡和发泡2种样品,进行了传统和微波冷冻干燥试验。结果表明,使用石英底盘,在30˚C、20 Pa下,发泡样品比未发泡样品冷冻干燥时间缩短了39.06%;施加1 W微波功率时,未发泡和发泡样品微波冷冻干燥时间比无微波时分别缩短了18.75%和12.82%。用碳化硅底盘替代石英底盘,在30˚C、20 Pa和1 W下,发泡样品微波冷冻干燥时间比未发泡和发泡样品传统无微波冷冻干燥分别缩短了65.62%和43.59%。分别以5.5%(w/w)的分离乳清蛋白和15.6%(w/w)的麦芽糊精为添加剂,进行了喷雾干燥试验。工艺参数为进风温度150˚C、出风温度85˚C、进料速度28 mL/min。冷冻干燥产品的甜菜红素、芦丁和总酚保留率分别在72%、84%和75%以上,而喷雾干燥产品的保留率显著降低。该研究采用的冷冻干燥方法能够大幅缩短干燥时间、提高产品质量,为浆果类粉末产品的制备提供工业解决方案。 展开更多
关键词 发泡 微波加热 冷冻干燥 喷雾干燥 甜菜红素 芦丁 总酚
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镁合金表面热喷涂WC-10Co-4Cr粒子沉积及分布特性 被引量:1
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作者 方敏 蒋理帅祎 +1 位作者 刘富强 张治民 《科学技术与工程》 北大核心 2024年第8期3186-3192,共7页
为了探究高速空气燃料热喷涂(activated combustion-high velocity air fuel,AC-HVAF)过程中喷涂粒子撞击基材后的沉积特性。采用AC-HVAF热喷涂技术在AZ80镁合金基体上沉积WC-10Co-4Cr硬质涂层。通过离散沉积实验获得薄层沉积粒子,探讨... 为了探究高速空气燃料热喷涂(activated combustion-high velocity air fuel,AC-HVAF)过程中喷涂粒子撞击基材后的沉积特性。采用AC-HVAF热喷涂技术在AZ80镁合金基体上沉积WC-10Co-4Cr硬质涂层。通过离散沉积实验获得薄层沉积粒子,探讨各种沉积形貌的种类、形成原因、结合机制及射流中粒子的径向和轴向分布。结果表明:在AC-HVAF粒子沉积过程中,嵌入型沉积为主要的沉积形貌,同时包含少量的破碎型与空腔型沉积粒子。在涂层的形成过程中,嵌入型沉积对涂层/基体结合性能起重要作用;空腔型沉积的小颗粒及破碎型沉积的大颗粒是造成沉积效率下降的主要原因。喷涂粒子主要集中在射流中心,越靠近射流边缘,空腔型沉积粒子越多,最终导致AC-HVAF粒子射流呈现出空间分布特征。 展开更多
关键词 超音速火焰喷涂 WC-10Co-4Cr 沉积状态 粒子射流 镁合金
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加热温度对工业规模CeCl_(3)喷雾焙烧反应器影响的数值模拟
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作者 董云芳 张松松 +3 位作者 王振峰 伍永福 刘中兴 刘铃声 《有色金属(冶炼部分)》 CAS 北大核心 2024年第6期85-96,共12页
CeO_(2)颗粒由于具有优异的性能,市场对CeO_(2)颗粒的需求逐年增加。为探究使用在氧化铁颗粒工业化生产的Ruthner型喷淋焙烧反应器生产CeO_(2)颗粒的可能性,结合单液滴失重试验,使用ANSYS Fluent软件,分别探究550、650、750和850℃四种... CeO_(2)颗粒由于具有优异的性能,市场对CeO_(2)颗粒的需求逐年增加。为探究使用在氧化铁颗粒工业化生产的Ruthner型喷淋焙烧反应器生产CeO_(2)颗粒的可能性,结合单液滴失重试验,使用ANSYS Fluent软件,分别探究550、650、750和850℃四种不同加热温度对反应器的影响。单液滴失重试验表明,氯化铈和氯化铁、氯化亚铁的热解过程基本一致,使用该型反应器制备CeO_(2)颗粒理论上可行。对小型工业反应器进行等比例建模,研究反应器内部化学反应的具体过程。结果表明,550℃是最合适的温度,对工业生产具有一定指导意义。 展开更多
关键词 氯化铈 喷雾热解 Ruthner型喷淋焙烧反应器 数值模拟
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单旋翼无人机植保作业系统的研制与实验研究 被引量:1
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作者 赵洪光 滕文建 《科技资讯》 2024年第1期9-13,55,共6页
为了提高植保无人机的工作效率,降低无人机的操作难度,研制了单旋翼无人机植保作业系统。根据植保作业流程,单旋翼无人机植保作业系统实现启动、预热、起飞、飞行、喷洒作业、加药和返航等全过程无人工干预的自动飞行作业。单旋翼无人... 为了提高植保无人机的工作效率,降低无人机的操作难度,研制了单旋翼无人机植保作业系统。根据植保作业流程,单旋翼无人机植保作业系统实现启动、预热、起飞、飞行、喷洒作业、加药和返航等全过程无人工干预的自动飞行作业。单旋翼无人机植保控制系统包括作业平台、飞行控制、数据链路、地面站系统、系统应用、飞行器管理、用户信息管理、专业知识管理、大数据业务,实现了喷洒区域的精准控制,地面站系统与飞行系统的控制与交互,植保信息的存贮与分析等。通过实验研究表明:单旋翼无人机植保作业系统有效提高了植保工作效率,降低了飞行操作人员的操作难度。 展开更多
关键词 无人机 植保 单旋翼 喷洒作业
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