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fragmentation Functions for Heavy Baryons in the Recombination Model

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Chinese Physics Letters 2011年第12期28卷 104-106页

作者： PENG Ru College of Science Wuhan University of Science and TechnologyWuhan 430065 Hubei Province Key Laboratory of Systems Science in Metallurgical Process Wuhan University of Science and TechnologyWuhan 430081

Using the shower parton distributions determined by the recombination model,we predict the fragmentation functions for heavy *** we obtain the completed fragmentation functions of heavy quarks(c and b)splitting into their hadrons(mesons and baryons containing one heavy valence quark).The calculated process shows that the fragmentation functions for mesons and baryons are not independent if the hadronization of the shower partons is taken into account.

关键词： fragmentation quark meson

fragmentation Behavior and Ionization Potentials of Lead Clusters Pb_n(n≤30)

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Chemical Research in Chinese Universities 2010年第6期26卷 996-1001页

作者： LI Xiao-ping ZHANG Wei LUE Wen-cai WANG Cai-zhuang HO Kai-ming State Key Laboratory of Theoretical and Computational Chemistry Institute of Theoretical Chemistry Jilin University Changchun 130021 P. R. China Laboratory of Fiber Materials and Modern Textile the Growing Base for State Key Laboratory College of Physics Qingdao University Qingdao 266071 P. R. China Ames Laboratory of US DOE and Department of Physics and Astronomy Iowa State University Ames IA 50011 USA

The properties of Pbn（n=2―30） clusters including binding energies,second differences in energy,and HOMO-LUMO gaps,especially fragmentation energies and ionization potentials,have been studied by ab initio *** main fragmentation products of Pbn＋ are shown to be Pb＋Pbn-1＋ for n≤14 and two small cluster fragments for larger ones with *** Pb13＋ appears frequently as the products in the fragmentations of large ***,the calculated ionization potentials of the clusters are consistent with the experiment data.

关键词： Pb cluster fragmentation Ionization potential

fragmentation Effects on Diversity of Wasp Community and Its Impact on Fig／Fig Wasp Interaction in Ficus racemosa L.

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Journal of Integrative Plant Biology 2005年第1期47卷 20-26页

作者： Rui-WuWANG Cheng-YunYANG Gui-FangZHAO Jun-XingYANG KunmingInstituteofZoology theChineseAcademyofSciencesKunming650223China／／GraduateSchooloftheChineseAcademyofSciencesBeijing100039China KunmingInstituteofZoology theChineseAcademyofSciencesKunming650223China／／CollegeofLifeSciencesNorthwestUniversityXi＇an710069China CollegeofLifeSciences NorthwestUniversityXi＇an710069China KunmingInstituteofZoology theChineseAcademyofSciencesKunming650223China

Abstract: Habitat fragmentation usually results in alteration of species composition or biological communities. However, little is known about the effect of habitat fragmentation on the fig/fig wasp system. In this study, we compared the structure of a fig wasp community and the interaction between figs and fig wasps of Ficus racemosa L. in a primary forest, a locally fragmented forest and a highly fragmented forest. Our results show that, in the highly fragmented forest, the proportion of pollinator wasps is lower and the proportion of non-pollinator wasps is higher compared with the primary forest and locally fragmented forest. The proportion of fruits without pollinator wasps in mature fruits is also greatly increased in the highly fragmented forest. The proportion of galls in all female flowers increases in the highly fragmented forest, whereas the proportion of viable seeds does not change considerably. The disruption of groups of fig trees results in a decrease in pollinator wasps and even might result in the extinction of pollinator wasps in some extreme cases, which may transform the reciprocal interaction between figs and fig wasps into a parasite/host system. Such an effect may lead to the local extinction of this keystone plant resource of rain forests in the process of evolution, and thereby, may change the structure and function of the tropical rain forest.

关键词： Ficus racemosa L. fig fig wasp fragmentation tropical rain forest

fragmentation Mechanism of Fullerenes in the Positive and Negative Ion Channels

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Chinese Physics Letters 2001年第8期18卷 1056-1059页

作者： KONG Qing-Yu ZHAO Li ZHUANG Jun QIAN Shi-Xiong LI Yu-Fen State Key Joint Laboratory for Materials Modification by Laser Ion and Electron Beamsand Department of PhysicsFudan UniversityShanghai 200433

The authors have performed the photofragmentation studies of pristine C_(60) and C_(60)/C_(70) composites on the reflectron time-of-flight mass spectrometer(RTOF MS)in the positive and negative ion *** mechanism of the formation of daughter fullerenes in the negative ion channel and the enhancement of fullerene coalescence reactions have been discussed compared to our previous studies on the linear *** 5 cm free expansion path in the RTOF experiments provides sufficient time and favorable environment for the electrons to attach to the neutral daughter species,so it is thought to play a key role for the appearance of strong mass peaks of anionic fragmentation and aggregation fullerene *** appearance of odd-numbered“fullerene”fragments is briefly discussed.

关键词： fragmentation (MS) neutral

fragmentation patterns and systematic transitions of the forested landscape in the upper Amazon region, Ecuador 1990-2008

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Journal of Forestry Research 2014年第2期25卷 301-309页

作者： Santiago Bonilla-Bedoya Juan R.Molina José E.Macedo-Pezzopane Miguel A.Herrera-Machuca DepartaTento de Ingeniería Forestal E.T.S.I.A.M.Universidad de CórdobaCaTpus de Excelencia Internacional Agroali Tentario (ceiA3) Secretaria Nacional de Educación Superior CienciaTecnología e Innovación del EcuadorWhy Tper E7-37 y Alpallana Quito. Ecuador Departa Tento de Engenharia Florestal Universidade Federal do Espírito Santo

The analysis of the systematic transitions in the forested landscape and the study of the forest fragmentation patterns allow us to deepen our understanding of the changes in the vegetation ground cover. The importance of knowing the intricate patterns of the land usage of the upper basin of the Amazon region is widely recognized. This zone is one of the most diverse biological areas in the world, is home to large areas of mature tropical cloud forest and demonstrates high probabilities of stable climatic conditions in light of global warming. The research quan- tiffed systematic transitions through the ＂loss＂ and ＂gain＂ of the different categories of landscape during the eighteen-year study period of the Ecuadorian Amazon Region （EAR）, the forest fragmentation patterns were also analyzed based on a set of indicators. Therefore, with respect to the entirety of the landscape, the results registered for the ground coverage in forested areas during the first period （1990-2000）, show a decrease of 6.99% and an increase of 0.68%; and during the second period （2000-2008）, show a decrease of 3.99% and an increase of 2.14%. It demonstrated that forest and agricultural areas tended to replace or be replaced by herbaceous vegetation faster than expected fortuitously. Finally, the indices of fragmentation signaled intense changes during the 1990-2000 period with a reduction during the period 2000-2008. Per- centages registered in the Largest Patch Index （LPI） were between 79.58%; 52.39% and 49.99% respectively; while the Patch Density （PD） varied between 0.04; 0.06 and 0.07. This suggests the propensity of for- est cover to remain intact. The results of this investigation suggest a tendency towards stability in Ecuador＇s Amazon landscape. Within the framework for development and management of this area, the tendency is natural regeneration. This permits a consolidation of the conservation, reforestation, forestation and agricultural forestry plans, programs and systems for the

关键词： Ecuadorian Amazon systematic transitions fragmentation natural regeneration

fragmentation model for large L/D (Length over Diameter) explosive fragmentation warheads

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Defence Technology（防务技术） 2017年第4期13卷 300-309页

作者： Vladimir M. Gold US Army RDECOM-ARDEC Attn: RDAR-MEE-F Picatinny Arsenal NJ 07806-5000 USA

New advanced numerical computer model enabling accurate simulation of fragmentation parameters of large Length over Diameter(L/D)explosively driven metal shells has been developed and *** newly developed large L/D multi-region model links three-dimensional axisymmetric high strain high strain-rate hydrocode analyses with the conventional set of Picatinny Arsenal fragmentation(PAFRAG)simulation *** standard PAFRAG modeling technique is based on the Mott's theory of break-up of idealized cylindrical"ring-bombs",in which the length of the average fragment is a function of the radius and velocity of the shell at the moment of break-up,and the mechanical properties of the *** the newly developed multi-region model,each of the shell region,the break-up is assumed to occur instantaneously,whereas the entire shell is modeled to fragment at multiple times,according to the number of the regions *** to PAFRAG methodology,the required input for both the natural and the controlled fragmentation models including the geometry and the velocity of the shell at moment of break-up had been provided from the hydrocode analyses and validated with available experimental *** newly developed large L/D multi-region PAFRAG model has been shown to accurately reproduce available experimental fragmentation data.

关键词： Explosive fragmentation modeling Natural fragmentation Mott model PAFRAG fragmentation warhead lethality performance

fragmentation Analyses of Granular Explosive Under Drop Weight Impact

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Journal of Beijing Institute of Technology 2019年第4期28卷 703-706页

作者： Yanqing Wu Zhao Zhang Hongfu Guo State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

Fragmental size and distribution of explosive particles play a more important role in the formation of hot-spot than original particles size under drop weight *** the particles breakage and the hot-spots ignition will form in a sequence between fragments and between the fragments and the drop weight surface under the *** this paper,the size and distribution of the cyclotetramethylenete tranitramine(HMX)fragments were analyzed by the Laser Particle Size Analyzer Malvern *** post-analysis results of fragments showed that size distribution of fragments was strongly dependent on drop *** empirical formula is established to describe the relationship between the average size and drop *** volume-based probability distribution of explosive fragments was also studied by experiments and theoretical calculations.

关键词： granular explosive fragmentation drop weight fragments size distribution hot spots

Rock fragmentation under different installation polar angles of TBM disc cutters

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Journal of Central South University 2017年第10期24卷 2306-2313页

作者： CHENG Yong-liang ZHONG Jue MEI Yong-bing XIA Yi-min State Key Laboratory of High Performance Complex Manufacturing Central South University China Railway Construction Heavy Industry Co. Ltd.

The disc cutters of tunnel boring machine(TBM) are installed with different polar angles. This causes the cutting depth difference between adjacent disc cutters on the tunnel face. A rock-cutting model was established to study the rock fragmentation law between adjacent disc cutters with different polar angles based on particle flow code(PFC). The influence of polar angle of adjacent disc cutters on rock cracks and stresses under different cutter spacing and penetration was studied. Research shows that polar angle difference leads to the discontinuity of rock-fragmentation process by adjacent cutters. The effect of rock-fragmentation is influenced by the cutting depth difference between adjacent cutters. The effect of rock-fragmentation performed best, meanwhile large rock blocks were flaked when the difference of cutting depth is half of the penetration. Too large or small difference of the cutting depth will cause high specific energy consumption of rock fragmentation. The specific energy consumption is relatively small when the difference of cutting depth is half of the penetration.

关键词： tunnel boring machine disc cutter polar angle particle flow code rock fragmentation

Preparation and Properties of PBXs Based on FOX-7 in Controlled fragmentation Warhead Application

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含能材料 2018年第10期26卷 843-849页

作者： Karim K Elsharkawy Lin Guo Ahmed M Enew School of Chemistry and Environment Beijing University of Aeronautics and Astronautics Chemical Department Faculty of EngineeringCairo University

Polymer bonded explosive(PBX)formulations were successfully prepared in the laboratory scale containing 1,1-diamino-2,2-dinitroethene(FOX-7)and hexogen(RDX)as brisant high explosives and different binder types of polyurethane(PU)based on glycidyl azide polymer(GAP) and hydroxyl-terminated polybutadiene(HTPB) as an energetic and inert polymeric binder *** technique was used for the preparation of different PBX formulations based on FOX-7/RDX and PU(GAP/HTPB)with 14% *** sensitivity to different initial impulses and performance characteristics of the explosive and lethal zone of the tested controlled fragmentation warhead by the fragmentation warhead assessment test(arena test)were studied,in which the arena test was carried out with a controlled fragmentation warhead made from Ck45 steel,with dimensions(100 mm length,30 mm outer diameter and 3 mm thickness).Results show that PBXGF4 has lower sensitivity to impact and heat than those of PBXGR4 by 188.4% and 3.2% *** friction sensitivity is the same as that of *** has better performance,in which detonation velocity increases by 2.1% and brisance increases by 0.5% when compared with those of *** was concluded that PBXGF4 which based on FOX-7 bonded with PU/GAP matrix has good characteristics as PBX,specially in the sensitivity to impact and can be applied for replacing PBXs based on RDX in the advanced PBXs for low sensitive fragmentation warheads.

关键词： polymer bonded explosive(PBX) controlled fragmentation warhead 1,1-diamino-2,2-dinitroethene(FOX-7) hexo-gen(RDX) preparation sensitivity performance characterization arena test