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Mix Proportion Optimization of RAC Based on Dry-Wet Close Packing Model 认领 引用
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作者 SUN Bo ZHANG Meixiang +3 位作者 YANG Xiaolin DING Yahong WANG Xingguo ZHANG Xianggang 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2026年第2期448-462,共15页
To explore mix proportion design of RAC with aggregates tightly packed,the dry and wet packing density of recycled coarse aggregates mixture system and recycled coarse and fine aggregates were tested,then the influenc... To explore mix proportion design of RAC with aggregates tightly packed,the dry and wet packing density of recycled coarse aggregates mixture system and recycled coarse and fine aggregates were tested,then the influence of replacement rate and particle size ratio on the packing density of particle system was explored,the packing density prediction model of recycled coarse aggregates based on particle morphology was constructed,and the mix proportion optimization for recycled aggregate concrete with dry-wet packing model was carried out.The experimental results show that,with the increasing of recycled aggregate replacement rate or fine-grained volume ratio,the dry packing density of recycled coarse aggregates decreases gradually.With the increasing of replacement rate,the particle gradation can be optimized by increasing coarsegrained volume ratio.There is a significant effect for particle morphology parameter K and the particle size ratio on the packing density of the binary mixed system,and the packing density prediction model of recycled coarse aggregates based on particle morphology was constructed.The maximum increase in compressive strength and tensile strength of RAC with mix proportion optimized by the dry-wet packing model are 12.94%and 11.09%,and the cementitious materials is reduced by 21.83%,then the superiority of the mix proportion optimization of RAC with the dry-wet close packing model is confirmed.The results of this paper can provide a theoretical basis for the mix proportion design of RAC. 展开更多
关键词 recycled aggregate concrete mix proportion design wet packing model aggregate morphology packing density
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Hierarchical algorithm for large-scale irregular packing problems 认领 引用
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作者 Xiao LIU 《ENGINEERING Information Technology & Electronic Engineering》 SCIE EI CSCD 2026年第3期69-80,共12页
To address the challenge of large-scale packing problems,this paper proposes a novel hierarchical algorithm based on the geometrical classification of parts.The algorithm begins by classifying parts into three levels ... To address the challenge of large-scale packing problems,this paper proposes a novel hierarchical algorithm based on the geometrical classification of parts.The algorithm begins by classifying parts into three levels based on their area and fullness and then applies distinct packing strategies to each category.An innovative“shape matching”method is introduced,which,together with the“box stacking”(for rectangular parts)and“gravity packing,”forms a comprehensive hierarchical packing system.Level-1 comprises large rectangular parts,which are arranged using the box stacking algorithm.By aligning the corner points of the parts’bounding boxes,this method avoids the hooking issue commonly encountered in gravity packing.Level-2 includes both large,irregular parts and medium-sized parts.They are first processed using the shape matching algorithm,where rotation and translation are applied to achieve contour complementarity.The quality of the match is evaluated using the shape matching coefficient(SMC).If the SMC fails to reach the preset quality threshold,the system switches to box stacking(for large,irregular parts)or gravity packing(for medium-sized parts).Level-3 comprises the remaining smaller parts and those that failed to pack in the previous two levels.For these parts,shape matching is attempted first,and the system resorts to gravity packing in case of failure.The experimental and comparative results demonstrate that the proposed hierarchical algorithm achieves higher material utilization than the traditional gravity packing algorithm.This improvement is facilitated by the box stacking and shape matching strategies,which promote a more orderly and compact arrangement of parts. 展开更多
关键词 Large-scale packing Hierarchical algorithm Box stacking Shape matching Gravity packing Principle of minimum potential energy
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Analysis of Geometrical Arrangement and Packing Material on Heat Generation in Lithium-Ion Battery Banks 认领 引用
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作者 Seenaa Khudhayer Salman Shaymaa Husham Abdulmalek +2 位作者 Ali Ahmed Gitan Thamer Khalif Salem Raaid Rashad Jassem Al-Doury 《Energy Engineering》 EI 2026年第2期578-601,共24页
Operating Lithium-ion batteries at their temperature limits is a challenging design task due to explosion risk at high temperatures and rapid degradation at low temperatures.Depending on the battery package design,tho... Operating Lithium-ion batteries at their temperature limits is a challenging design task due to explosion risk at high temperatures and rapid degradation at low temperatures.Depending on the battery package design,those risks can be solved with passive solutions,which require no active cooling or heating.Thecurrentwork aims to optimize the pack design and materials of the type-NCR18650B battery based on a wide range of operation temperature.The lower limit was denoted by cold case while the maximum limit was expressed by hot case.A combined analyticalnumerical approach was developed to model the heat generation inside the battery.A thermal resistance analysis was used to determine the boundary conditions of the numerical model.The governing differential equations for the 1-D heat generation model were solved analytically.The numerical analysis was considered to determine the best battery pack design based on material parameters,number of batteries,and geometrical arrangement.The analytical results revealedthat the cold case canbe selectedas theworst case and thebestmodel wasobtainedusing thehexagonal-shaped 10-battery pack that was covered with Delrin of 1.8 mm in thickness.The numerical results showed that the best model was the hexagonal-shaped 10-battery pack with Delrin of 2 mm in thickness that achieved the largest temperature of−20.6℃ in the cold case. 展开更多
关键词 Analytical analysis battery package battery package configuration battery packing safety lithium-ion battery thermal performance
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Efficient C3H6/C3H8 separation within a bifunctional ultramicroporous metal-organic framework with high purity and record packing density 认领 引用 被引量：2
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作者 Shan-Qing Yang Lu-Lu Wang +7 位作者 Rajamani Krishna Bo Xing Lei Zhou Fei-Yang Zhang Qiang Zhang Yi-Long Li Chao-Sheng Bao Tong-Liang Hu 《Chinese Chemical Letters》 SCIE CAS CSCD 2025年第12期500-504,共5页
The propylene/propane(C3H6/C3H8)separation is particularly challenging due to their highly similar physical properties,but of industrial importance.Herein,we report a bifunctional ultramicroporous metal-or... The propylene/propane(C3H6/C3H8)separation is particularly challenging due to their highly similar physical properties,but of industrial importance.Herein,we report a bifunctional ultramicroporous metal-organic framework(Co-aip-pyz)with customized pore environment and selective binding sites for the challenging C3H6/C3H8 separation.Co-aip-pyz exhibits a good C3H6 uptake with an ultrahigh C3H6 packing density(931 g/L),as well as possesses a remarkable C3H6/C3H8 uptake ratio with 911% and distinguished C3H6/C3H8 selectivity(>104)at 298 K and 1.0 bar.Furthermore,Co-aip-pyz possesses a record high C3H6 packing density with 859 g/L at 313 K and 1.0 bar,which is unprecedented in the C3H6/C3H8 separation.Its high performance for the C3H6/C3H8 separation has been further confirmed by breakthrough experiments and molecular simulations.Combined with good stability,facilely synthesized procedure by low-cost precursors,record-high C3H6 packing density,as well as good C3H6/C3H8 separation performance,it highlights Co-aip-pyz as a benchmark adsorbent to address daunting challenge for industrial C3H6/C3H8 separation.This work provides valuable insights into constructing top-performing MOF materials for addressing the industrial separation challenges. 展开更多
关键词 Metal-organic frameworks Gas adsorption and separation C3H6purification C3H6/C3H8separation C3H6packing density
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π-π2max:Bridging molecular characteristics to crystal packing in nitro-containing two-dimensional energetic materials 认领 引用 被引量：1
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作者 Xiaokai He Chao Chen +4 位作者 Zhixiang Zhang Linyuan Wen Yiding Ma Yilin Cao Yingzhe Liu 《Defence Technology（防务技术）》 SCIE EI CAS CSCD 2025年第7期192-202,共11页
Two-dimensional energetic materials(2DEMs),characterized by their exceptional interlayer sliding properties,are recognized as exemplar of low-sensitivity energetic materials.However,the diversity of available 2DEMs is... Two-dimensional energetic materials(2DEMs),characterized by their exceptional interlayer sliding properties,are recognized as exemplar of low-sensitivity energetic materials.However,the diversity of available 2DEMs is severely constrained by the absence of efficient methods for rapidly predicting crystal packing modes from molecular structures,impeding the high-throughput rational design of such materials.In this study,we employed quantified indicators,such as hydrogen bond dimension and maximum planar separation,to quickly screen 172DEM and 16 non-2DEM crystal structures from a crystal database.They were subsequently compared and analyzed,focusing on hydrogen bond donor-acceptor combinations,skeleton features,and intermolecular interactions.Our findings suggest that theπ-πpacking interaction energy is a key determinant in the formation of layered packing modes by planar energetic molecules,with its magnitude primarily influenced by the strongest dimericπ-πinteraction(π-π2max).Consequently,we have delineated a critical threshold forπ-π2max to discern layered packing modes and formulated a theoretical model for predictingπ-π2max,grounded in molecular electrostatic potential and dipole moment analysis.The predictive efficacy of this model was substantiated through external validation on a test set comprising 31 planar energetic molecular crystals,achieving an accuracy of 84%and a recall of 75%.Furthermore,the proposed model shows superior classification predictive performance compared to typical machine learning methods,such as random forest,on the external validation samples.This contribution introduces a novel methodology for the identification of crystal packing modes in 2DEMs,potentially accelerating the design and synthesis of high-energy,low-sensitivity 2DEMs. 展开更多
关键词 Two-dimensionalenergeticmaterials Maximum planar separation Hydrogen bond dimension Hydrogen bond donor-acceptor π-πinteraction energy prediction Crystal packing modes identification
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Effects of Zr2Cu Packing Modification on Microstructure and Mechanical and Ablation Properties of PIP-Prepared C/C-SiC-ZrC Composites 认领 引用
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作者 Xie Jing Zhang Qian +6 位作者 Ren Jing Su Hailong Tian Lulu Zhi Xionghui Sun Guodong Li Hui Wang Long 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2025年第8期1940-1946,共7页
To improve the compactness and properties of C/C-SiC-ZrC composites produced by precursor infiltration and pyrolysis(PIP)method,the low-temperature reactive melt infiltration(RMI)process was used to seal the composite... To improve the compactness and properties of C/C-SiC-ZrC composites produced by precursor infiltration and pyrolysis(PIP)method,the low-temperature reactive melt infiltration(RMI)process was used to seal the composites using Zr2Cu as the filler.The microstructure,mechanical properties,and ablation properties of the Zr2Cu packed composites were analyzed.Results show that during Zr2Cu impregnation,the melt efficiently fills the large pores of the composites and is converted to ZrCu due to a partial reaction of zirconium with carbon.This results in an increase in composite density from 1.91 g/cm3to 2.24 g/cm3and a reduction in open porosity by 27.35%.Additionally,the flexural strength of Zr2Cu packed C/C-SiC-ZrC composites is improved from 122.78±8.09 MPa to 135.53±5.40 MPa.After plasma ablation for 20 s,the modified composites demonstrate superior ablative resistance compared to PIP C/C-SiC-ZrC,with mass ablation and linear ablation rates of 2.77×10−3g/s and 2.60×10−3mm/s,respectively.The“selftranspiration”effect of the low-melting point copper-containing phase absorbs the heat of the plasma flame,further reducing the ablation temperature and promoting the formation of refined ZrO2particles within the SiO2melting layer.This provides more stable erosion protection for Zr2Cu packed C/C-SiC-ZrC composites. 展开更多
关键词 C/C-SiC-ZrC composites Zr2Cu packing microstructure mechanical property ablation property
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Reduction of photoreceptor cell packing density in low or moderative myopia detected with adaptive optics scanning laser ophthalmoscopy 认领 引用
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作者 Lin-Yi Lei Yue Zhao +2 位作者 Tang-Ren Cai Si-Guo Feng Jin Yao 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2025年第4期683-690,共8页
AIM:To assess the variations in photoreceptor cell packing density(PCPD)across the retina among young healthy individuals with emmetropia,low and moderate myopia.METHODS:High-resolution adaptive optics scanning laser ... AIM:To assess the variations in photoreceptor cell packing density(PCPD)across the retina among young healthy individuals with emmetropia,low and moderate myopia.METHODS:High-resolution adaptive optics scanning laser ophthalmoscopy(AOSLO)systems were utilized for retinal imaging with a large sampling window of 700μm×700μm.The study cohort included 14 emmetropic[spherical equivalent(SE)ranged+0.5 to-0.5 D],15 low myopic(SE ranged-0.5 to-3 D)and 21 moderate myopic(SE ranged-3 to-6 D)healthy young adults.Photoreceptors at 3°temporal,6°superior and inferior 6°were captured.Statistical analysis was then performed to obtain PCPD and cell spacing.RESULTS:The average age of participants was 22.54±2.86(ranged 20–30y)with no difference among 3 groups.At 3°temporal,the emmetropic group exhibited the highest PCPD of 15186.16±2050.54 cells/mm2,while the low and moderate myopic groups had PCPD of 14009.15±1073.01 and 13466.92±1121.71 cells/mm2,respectively.At 3°temporal,the emmetropic group also had the smallest cell spacing at 6.66±0.26 mm,compared to 6.85±0.26 and 6.91±0.28 mm for the low and moderate myopic groups,respectively.Compared to the emmetropic group,at 3°temporal,the myopic groups showed significantly reduced PCPD(low myopia:P=0.032;moderate myopia:P=0.001).At 6°inferior,the moderate myopic group exhibited a significant decrease in PCPD(P=0.013),while at 6°superior,there were no significant statistical differences in PCPD for the low and moderate myopic groups(P>0.05).In comparison to the emmetropic group,only the moderate myopic group showed significantly increased cell spacing at all three positions(temporal 3°:P=0.011,superior 6°:P=0.046,inferior 6°:P=0.013).Correlation analysis revealed a positive correlation between PCPD and axial length changes(P<0.05).CONCLUSION:Reduced PCPD and increased cell spacing strongly correlated with refractive error in mild to moderate myopic eyes,especially at 6°inferior to the fovea and the decreased PCPD in the macular region of myopic patients may be associated with increased axial lengthinduced retinal stretching. 展开更多
关键词 adaptive optics scanning laser ophthalmoscopy photoreceptor cell packing density fovea refractive error myopia
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The Character of Thurston’s Circle Packings with Obtuse Exterior Intersection Angles 认领 引用
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作者 Chunlei Liu 《Analysis in Theory and Applications》 CSCD 2025年第1期80-98,共19页
We study the character of Thurston’s circle packings with obtuse exterior intersection angles,and we get some simple criteria for the existence of hyperbolic circle packings.Moreover,the compactness theorem of combin... We study the character of Thurston’s circle packings with obtuse exterior intersection angles,and we get some simple criteria for the existence of hyperbolic circle packings.Moreover,the compactness theorem of combinatorial Ricci flows in hyperbolic background geometry with the weight function Ф∈[0,π)is obtained.As a consequence,We generalize G.Lin’s result[12]from acute exterior intersection angles case to obtuse exterior intersection angles case. 展开更多
关键词 Character Thurston’s circle packing combinatorial Ricci flow obtuse exterior intersection angles
求解单位等边三角形Packing问题的近似算法 认领 引用 被引量：7
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作者 陈传波 何大华 黄文奇 《计算机学报》 EI CAS 北大核心 2003年第2期212-220,共9页
多边形Packing问题不仅具有重要的理论意义 ,而且也有广阔的应用前景 .由于该问题具有NP难度 ,且具有连续的性质 ,一般要事先对多边形的放置方位进行限制 ,例如不允许多边形旋转 ,然后再进行优化求得近似解 .该文采用一种新的思路对多边... 多边形Packing问题不仅具有重要的理论意义 ,而且也有广阔的应用前景 .由于该问题具有NP难度 ,且具有连续的性质 ,一般要事先对多边形的放置方位进行限制 ,例如不允许多边形旋转 ,然后再进行优化求得近似解 .该文采用一种新的思路对多边形Packing问题的一个特例———单位等边三角形Packing问题进行了研究 ,提出了零自由度动作和零自由度放置策略的概念 ,并设计了一个近似求解算法———最小损伤法 .复杂性分析和计算结果表明该算法是高效的 .以此为基础 ,可能为多边形Packing问题找到类似的求解算法 . 展开更多
关键词 单位等边三角形Packing问题 近似算法 最小损伤法 价值度 NP问题 计算机 多边形Packing问题
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Computer Simulation of Random Packing of Spherical Particles in Two Dimensions 认领 引用 被引量：2
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作者 戴宏钦 白伦 +2 位作者 詹葵花 孙自玲 关国平 《Journal of Donghua University(English Edition)》 EI CAS 2011年第1期31-34,共4页
Random packings of spherical particles have attracted attention for many years.An algorithm based on compression is developed to generate random packings of spherical particles in this paper.This method is different f... Random packings of spherical particles have attracted attention for many years.An algorithm based on compression is developed to generate random packings of spherical particles in this paper.This method is different from previous compression-based algorithm.In order to increase the packing density,a process of shaking is applied during packing process.The algorithm is mainly composed of three procedures:generating initial packing configuration by using random sequential adsorption(RSA),compressing packing domain,and shaking.The packing structure is characterized by packing density and coordinate number.The packing density increases with iteration number and a stable packing configuration is obtained after the iteration number is more than 34 000.The packing density is 0.85 and the average coordinate number is 3.7 in a stable packing configuration. 展开更多
关键词 random packing packing density compression coordination number
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RELATIONS BETWEEN PACKING PREMEASURE AND MEASURE ON METRIC SPACE 认领 引用 被引量：5
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作者 文胜友 吴敏 《Acta Mathematica Scientia》 SCIE 2007年第1期137-144,共8页
Let X be a metric space and u a finite Borel measure on X. Let P^- u^q,t and P u^q,t be the packing premeasure and the packing measure on X, respectively, defined by the gauge （uB（x, r））^q（2r）^t, where q, t ∈ R... Let X be a metric space and u a finite Borel measure on X. Let P^- u^q,t and P u^q,t be the packing premeasure and the packing measure on X, respectively, defined by the gauge （uB（x, r））^q（2r）^t, where q, t ∈ R. For any compact set E of finite packing premeasure the authors prove： （1） if q ≤ 0 then P^- u^q,t（E） =P u^q,t （E）; （2） if q 〉 0 and u is doubling on E then P^- u^q,t （E） and P u^q,t （E） are both zero or neither. 展开更多
关键词 Doubling condition packing premeasure packing measure
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Effect of Packing Parameters and Gate Size on Shrinkage of Aspheric Lens Parts 认领 引用 被引量：2
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作者 胡广洪 崔振山 《Journal of Shanghai Jiaotong university(Science)》 EI 2010年第1期84-87,共4页
In order to produce the high quality optical aspheric lens,the shrinkage of lens should be strictly controlled during the injection process.Serials of experiments are done to find the factors that affect the lens shri... In order to produce the high quality optical aspheric lens,the shrinkage of lens should be strictly controlled during the injection process.Serials of experiments are done to find the factors that affect the lens shrinkage during the injection molding process.The study is focused on the effect of gate size,packing time and pressure on the shrinkage.The gate size decides the effective packing time.Only when the effective packing time is enough,the shrinkage size will be decreased along with the packing pressure increased.However the packing time is determined by the gate size.But big gate size is not easily to be cut and the cutting difficulty will cause the part quality problems.The experiments show that packing pressure not only determines the part shrinkage size and also affects the part shrinkage uniformity.When the packing pressure is more than a critical one,the effect of packing pressure on the shrinkage size becomes smaller.And the shrinkage uniformity is guaranteed. 展开更多
关键词 aspheric lens packing time packing pressure gate size part shrinkage
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On Packing Trees into Complete Bipartite Graphs 认领 引用 被引量：1
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作者 PENG Yanling WANG Hong 《Wuhan University Journal of Natural Sciences》 CAS CSCD 2023年第3期221-222,共2页
Let Bn(X,Y)denote the complete bipartite graph of order n with vertex partition sets X and Y.We prove that for each tree T of order n,there is a packing of k copies of T into a complete bipartite graph Bn+m(X,Y)... Let Bn(X,Y)denote the complete bipartite graph of order n with vertex partition sets X and Y.We prove that for each tree T of order n,there is a packing of k copies of T into a complete bipartite graph Bn+m(X,Y).The ideal of the work comes from the"Tree packing conjecture"made by Gyráfás and Lehel.Bollobás confirmed the"Tree packing conjecture"for many small trees,who showed that one can pack T1,T2,…,Tn/√2into Knand that a better bound would follow from a famous conjecture of Erdo s.In a similar direction,Hobbs,Bour geois and Kasiraj made the following conjecture:Any sequence of trees T2,…,Tn,with Tihaving order i,can be packed into Kn-1,(n/2).Further Hobbs,Bourgeois and Kasiraj proved that any two trees can be packed into a complete bipartite graph Kn-1,(n/2).Motivated by these results,Wang Hong proposed the conjecture:For each tree T of order n,there is a k-packing of T in some complete bipartite graph Bn+k-1(X,Y).In this paper,we prove a weak version of this conjecture. 展开更多
关键词 packing of graphs tree packing conjecture embedding of graph
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PACKINGS OF THE COMPLETE DIRECTED GRAPH WITH m-CIRCUITS 认领 引用 被引量：3
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作者 LIANG ZHIHE AND KANG QINGDE 《Applied Mathematics(A Journal of Chinese Universities)》 1998年第4期463-472,共10页
A packing of the complete directed symmetric graph DK v with m circuits, denoted by ( v,m) DCP, is defined to be a family of arc disjoint m circuits of DK v such that any one arc of DK v \ occurs in at most one m circ... A packing of the complete directed symmetric graph DK v with m circuits, denoted by ( v,m) DCP, is defined to be a family of arc disjoint m circuits of DK v such that any one arc of DK v \ occurs in at most one m circuit. The packing number P(v,m) is the maximum number of m circuits in such a packing. The packing problem is to determine the value P(v,m) for every integer v≥m. In this paper, the problem is reduced to the case m+6≤v≤2m- 4m-3+12 , for any fixed even integer m≥4 . In particular, the values of P(v,m) are completely determined for m=12 , 14 and 16. 展开更多
关键词 Complete directed graph m-circuit packing packing number
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Hydrodynamics and Mass Transfer of Jet Co-flow Packing Tray 认领 引用
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作者 刘国标 兰仁水 +1 位作者 王树楹 余国琮 《Chinese Journal of Chemical Engineering》 SCIE EI CAS 2005年第1期131-134,共4页
The jet co-flow packing tray(JCPT) with three different types of perforation in equal opening fraction was tested in two rectangular columns with 0.12m in width and 0.27m in length operated with air-water system. The ... The jet co-flow packing tray(JCPT) with three different types of perforation in equal opening fraction was tested in two rectangular columns with 0.12m in width and 0.27m in length operated with air-water system. The influences of gas phase orifice F-factor and clear liquid height Hc on the amount of liquid lifted, Q, were examined. The corresponding correlation between Q with F-factor and equivalent diameter of perforated holes as well as Hc was obtained. Furthermore, the non-steady state mass transfer performance of JCPT was tested by the humidification of air with water. Finally, by the analysis of data and comparison, it was found that the JCPT tray with single cap and two holes exhibited the highest mass transfer efficiency and best performance. 展开更多
关键词 packing tray mass transfer tray efficiency jet co-flow packing tray
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Packing 4-Partite Tree into Complete 4-Partite Graph 认领 引用
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作者 PENG Yanling 《Wuhan University Journal of Natural Sciences》 CAS CSCD 2024年第3期239-241,共3页
For graphs G and H,an embedding of G into H is an injection ϕ:V(G)→V(H)such that ϕ(a)ϕ(b)∈E(H)whenever ab∈E(G).A packing of p graphs G1,G2,…,Gp into H is a p-tupleΦ=(ϕ1,ϕ2,…,ϕp)such that,for i=... For graphs G and H,an embedding of G into H is an injection ϕ:V(G)→V(H)such that ϕ(a)ϕ(b)∈E(H)whenever ab∈E(G).A packing of p graphs G1,G2,…,Gp into H is a p-tupleΦ=(ϕ1,ϕ2,…,ϕp)such that,for i=1,2,…,p,ϕi is an embedding of Gi into H and the p sets ϕi(E(Gi))are mutually disjoint.Motivated by the"Tree Packing Conjecture"made by Gyar fas and Lehel,Wang Hong conjectured that for each k-partite tree,there is a packing of two copies of T(X)into a complete k-partite graph Bn+m(Y),where m=■k/2」..In this paper,we confirm this conjecture for k=4. 展开更多
关键词 packing of graph tree packing conjecture embedding of graph
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概率空间(Ω,F,μ)中关于μ的packing维数与经典的实直线上的packing维数之间的关系 认领 引用
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作者 戴朝寿 《数学杂志》 北大核心 1995年第4期517-522,共6页
本文将概率空刚（Ω，μ）中packing维数的定义与经典的实直线上的packing维数的定义相联系，证明了在Lebesgue情形，对所有的A∈，关于μ的packing维数Dim＿μ（A）与被Taylor和Tricot所定义的packing维数Dim（A）是一致的。Billingsle... 本文将概率空刚（Ω，μ）中packing维数的定义与经典的实直线上的packing维数的定义相联系，证明了在Lebesgue情形，对所有的A∈，关于μ的packing维数Dim＿μ（A）与被Taylor和Tricot所定义的packing维数Dim（A）是一致的。Billingsley的结果与我们的结果相结合，表明在Lebesgue情形，关于μ的分形与被Taylor所定义的分形是一致的。 展开更多
关键词 packing测度 packing维数 分形 概率空间
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A 2D Elliptical Model of Random Packing for Aggregates in Concrete 认领 引用 被引量：10
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作者 XU Wenxiang CHEN Huisu LV Zhong 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2010年第4期717-720,共4页
In the present work,a computer model was developed to simulate random packing of aggregates.For the sake of simplicity,two dimensional situation was considered and all of the aggregates in concrete were assumed as ell... In the present work,a computer model was developed to simulate random packing of aggregates.For the sake of simplicity,two dimensional situation was considered and all of the aggregates in concrete were assumed as ellipse.2D elliptical models of random packing were firstly demonstrated in periodic boundary condition.In addition,the ellipse random packing model was employed for the influence of aspect ratios on the packing fraction of ellipses.The modeling results demonstrate that the packing fraction of ellipses firstly increases then drops down with increasing aspect ratio.The maximal random packing fraction is 0.66 when aspect ratio is 1.04 in the periodic boundary condition. 展开更多
关键词 ellipse overlap random packing periodic boundary aspect ratio packing fraction
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Packing and film thickness theories for the mix design of high-performance concrete 认领 引用 被引量：17
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作者 Pui-Lam NG Albert Kwok-Hung KWAN Leo Gu LI 《Journal of Zhejiang University-SCIENCE A》 SCIE EI CAS CSCD 2016年第10期759-781,共23页
A high-performance concrete （HPC） is required to have superior performance in various aspects such as workability,strength, durability, dimensional stability, segregation stability, and passing ability. The mix desi... A high-performance concrete （HPC） is required to have superior performance in various aspects such as workability,strength, durability, dimensional stability, segregation stability, and passing ability. The mix design of HPC is rather complicatedbecause the number of ingredients in HPC is usually more than those in conventional concrete and some of the required propertiesare conflicting with each other in the sense that improvement in one property would at the same time cause impairment of anotherproperty. However, there is still lack of understanding regarding how the various mix parameters should be optimised forachieving best overall performance. Most practitioners are still conducting mix design primarily through trial concrete mixing,which is laborious, ineffective, and often unable to timely respond to fluctuations in the properties of raw materials. To addressthese issues, the authors have been developing the packing and film thickness theories of concrete materials, in order to revamp themix design philosophy of HPC in terms of the water film thickness （WFT）, paste film thickness （PFT）, and mortar film thickness（MFT） in the concrete. Based on the findings from an extensive experimental programme, suitable ranges ofWFT, PFT, and MFThave been recommended. 展开更多
关键词 Concrete mix design, Concrete science, Film thickness, High-performance concrete, Packing density, Sustainability
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基于动作空间求解二维矩形Packing问题的高效算法 认领 引用 被引量：22
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作者 何琨 黄文奇 金燕 《软件学报》 EI CSCD 北大核心 2012年第5期1037-1044,共8页
对于二维矩形Packing这一典型的NP难度问题,在黄文奇等人提出的拟人型穴度算法的基础上,通过定义动作空间来简化对不同放入动作的评价,使穴度的计算时间明显缩短,从而使算法能够快速地得到空间利用率较高的布局图案.实验测试了Hopper和T... 对于二维矩形Packing这一典型的NP难度问题,在黄文奇等人提出的拟人型穴度算法的基础上,通过定义动作空间来简化对不同放入动作的评价,使穴度的计算时间明显缩短,从而使算法能够快速地得到空间利用率较高的布局图案.实验测试了Hopper和Turton提出的21个著名的二维矩形Packing问题的实例.改进的算法对其中的每一个实例都得到了空间利用率为100%的最优布局,且在普通PC机上的平均计算时间未超过7分钟.实验结果表明,基于动作空间对拟人型穴度算法所进行的改进是明显而有效的. 展开更多
关键词 NP难度 矩形Packing 拟人 动作空间 穴度
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