A conflict is an event in which two or more aircraft experience a loss of minimum separation. In this paper, we formulate the problem of solving conflicts arising among several aircraft moving in a shared airspace as ...A conflict is an event in which two or more aircraft experience a loss of minimum separation. In this paper, we formulate the problem of solving conflicts arising among several aircraft moving in a shared airspace as a Constraint Satisfaction Problem (CSP). The constraint satisfaction problem being NP-complete, the algorithms developed to solve it have been of two types: non-systematic and systematic search methods. In this paper, we have considered a breakout algorithm as an example of non-systematic search methods and a backtracking procedure that maintains Arc Consistency (MAC) as an example of systematic search methods. The performance of these algorithms was compared experimentally and the Breakout algorithm is shown to be clearly superior.展开更多
Cocrystallization integrates the merits of high energy and insensitivity between energetic molecules to obtain energetics with satisfying performance.However,how to obtain supramolecular synthons accurately and rapidl...Cocrystallization integrates the merits of high energy and insensitivity between energetic molecules to obtain energetics with satisfying performance.However,how to obtain supramolecular synthons accurately and rapidly for predicting the structure and property of cocrystal remains a challenging problem.In this research,an efficient systematic search approach to predict CL-20/2,4-DNI cocrystal has been proposed that 2,4-DNI revolves around CL-20 with a stoichiometric ratio of 1:1 in accordance with the specified rules(hydrogen bond length:2.2-3.0 Å;search radius:6.5 Å;the number of hydrogen bond:1-3).Eight possible supramolecular synthons were obtained by combining quantum chemistry with molecular mechanics.Crystal structure prediction indicated that there are four structures in cocrystal,namely P21/c,P212121,Pbca and Pna21,and CL-20/2,4-DNI cocrystal is likely to be P21/c and the corresponding cell parameters are Z=4,a=8.28 Å,b=12.17 Å,c=20.42 Å,α=90°,β=96.94°,γ=90°,and ρ=1.9353 g/cm^(3).To further study the intermolecular interaction of CL-20/2,4-DNI cocrystal,a series of theoretical analyses were employed including intermolecular interaction energy,electrostatic potential(ESP),Density of State(DOS),Hirshfeld surface analysis.The C-H…O hydrogen bonds are demonstrated as the predominant driving forces in the cocrystal formation.The mechanical properties and detonation properties of CL-20/2,4-DNI cocrystal implies that the cocrystal shows better ductility and excellent detonation performances(9257 m/s,39.27 GPa)and can serve as a promising energetic material.Cocrystal structure predicted was compared with the experimental one to verify the accuracy of systematic search approach.There is a less than 8.8%error between experiment and predict results,indicating the systematic search approach has extremely high reliability and accuracy.The systematic search approach can be a new strategy to search supramolecular synthons and identify structures effectively and does have the potential to promote the develo展开更多
目的全面分析细胞实验系统评价/Meta分析(SRs/MAs)检索策略的制定和报告现状,为后续相关研究的开展提供参考依据。方法计算机检索PubMed、CNKI和Wanfang Data,检索时限均为建库截至2017年10月。结果最终纳入细胞实验SRs/MAs共82篇,其中...目的全面分析细胞实验系统评价/Meta分析(SRs/MAs)检索策略的制定和报告现状,为后续相关研究的开展提供参考依据。方法计算机检索PubMed、CNKI和Wanfang Data,检索时限均为建库截至2017年10月。结果最终纳入细胞实验SRs/MAs共82篇,其中英文79篇,中文3篇。64.63%(53/82)的研究报告了文献筛选流程图,6.10%(5/82)报告了检索人员的资质,45.13%(37/82)报告了至少一个完整的检索策略。有18.29%(15/82)的细胞实验SRs/MAs仅检索了1个数据库,检索5个以上数据库的研究仅9.76%(8/82)。此外,有53.66%(44/82)和8.54%(7/82)的研究中分别进行了其他方法的补充检索和灰色文献检索。在检索方式上,以DI(疾病+干预措施)的方式最为常见。结论目前已发表的细胞实验SRs/MAs在检索策略制定和报告方面均存在一定局限性,并无共识标准或规范的方法。因此,今后的研究有必要:①在数据库的选择上,除检索PubMed、EMBASE外,应对Web of Science、Scoups等数据库也进行检索。此外,对于灰色文献的收集,包括会议资料等阴性结果或未发表研究的收集需要更加关注;②在细胞实验SRs/MAs检索词的选择方面,除涉及的细胞及其干预措施外,涉及到测量指标的检索词亦是重要的参考依据;③研发细胞实验SRs/MAs的报告规范,以提高其报告质量,包括提供至少一个数据库完整的检索策略、提高检索人员的资质等相关信息的报告度。展开更多
文摘目的对国内外动物实验系统评价/Meta分析(SR/MA)检索策略的全面性及报告现状进行调查分析,为今后动物实验SR/MA检索策略的制定和报告提供参考依据。方法计算机检索Ovid-MEDLINE、Ovid-EMbase、Ovid-BIOSIS Previews、CBM、CNKI、VIP和WanFang Data数据库,检索时间均从建库至2015年1月。纳入国内外医学相关的动物实验SR/MA,不限动物种属。采用自制的资料提取表提取纳入研究的基本特征、检索数据库、其他检索来源、检索策略等相关信息,采用百分比和频数进行统计描述。结果最终纳入181篇动物实验SR/MA。不足30%的SR/MA检索了3个以上的数据库,65.7%报告进行了补充检索。86.2%(156/181)的SR/SMA研究报告了检索词,而报告完整检索策略的仅有12个;33个SR/MA的检索词包含了具体的动物名称,27个SR/SMA使用了"animal/experimental model/"一词,20个使用了"limit to animal"的限定功能。71.3%的SR/MA报告了具体的检索时间范围,44.2%报告说明了是否对纳入研究进行语种限制,其中的23.8%限制语种,且多限定为英文。结论目前,国内外的动物实验SR/MA在数据库、检索词以及检索策略的选择、报道上仍存在一些问题,因此我们建议:1在数据库的选择上,需要根据研究领域的不同尽可能选择足够具有代表性的多个数据库,外文数据库建议至少检索MEDLINE/PubMed、EMbase、BIOSIS Preview,中文数据库建议至少检索CBM、CNKI和WanFang Data;2根据研究对象将具体动物种属名称和(或)"animal(动物)"作为检索词进行检索,并根据数据库的特点使用"limit to animal"功能;3动物实验SR/MA的检索策略报告应该包括检索来源、检索时间范围、语种限制、研究类型限制、检索词以及完整的检索策略。此外,需要报告检索人员的资质;4有关期刊需要将"完整地报告检索策略"引入稿约,以提高SR/SMA的透明度和可信度。
文摘A conflict is an event in which two or more aircraft experience a loss of minimum separation. In this paper, we formulate the problem of solving conflicts arising among several aircraft moving in a shared airspace as a Constraint Satisfaction Problem (CSP). The constraint satisfaction problem being NP-complete, the algorithms developed to solve it have been of two types: non-systematic and systematic search methods. In this paper, we have considered a breakout algorithm as an example of non-systematic search methods and a backtracking procedure that maintains Arc Consistency (MAC) as an example of systematic search methods. The performance of these algorithms was compared experimentally and the Breakout algorithm is shown to be clearly superior.
基金the support of the National Natural Science Foundation of China(No.22005090)Beijing Institute of Technology Research Fund Program for Young Scholars+2 种基金the National Natural Science Foundation of China(No.11672040 and No.21801016)Open Research Fund Program of Science and Technology on Aerospace Chemical Power Laboratory(STACPL120201B02)the State Key Laboratory of Explosion Science and Technology(No.YB2016-17)。
文摘Cocrystallization integrates the merits of high energy and insensitivity between energetic molecules to obtain energetics with satisfying performance.However,how to obtain supramolecular synthons accurately and rapidly for predicting the structure and property of cocrystal remains a challenging problem.In this research,an efficient systematic search approach to predict CL-20/2,4-DNI cocrystal has been proposed that 2,4-DNI revolves around CL-20 with a stoichiometric ratio of 1:1 in accordance with the specified rules(hydrogen bond length:2.2-3.0 Å;search radius:6.5 Å;the number of hydrogen bond:1-3).Eight possible supramolecular synthons were obtained by combining quantum chemistry with molecular mechanics.Crystal structure prediction indicated that there are four structures in cocrystal,namely P21/c,P212121,Pbca and Pna21,and CL-20/2,4-DNI cocrystal is likely to be P21/c and the corresponding cell parameters are Z=4,a=8.28 Å,b=12.17 Å,c=20.42 Å,α=90°,β=96.94°,γ=90°,and ρ=1.9353 g/cm^(3).To further study the intermolecular interaction of CL-20/2,4-DNI cocrystal,a series of theoretical analyses were employed including intermolecular interaction energy,electrostatic potential(ESP),Density of State(DOS),Hirshfeld surface analysis.The C-H…O hydrogen bonds are demonstrated as the predominant driving forces in the cocrystal formation.The mechanical properties and detonation properties of CL-20/2,4-DNI cocrystal implies that the cocrystal shows better ductility and excellent detonation performances(9257 m/s,39.27 GPa)and can serve as a promising energetic material.Cocrystal structure predicted was compared with the experimental one to verify the accuracy of systematic search approach.There is a less than 8.8%error between experiment and predict results,indicating the systematic search approach has extremely high reliability and accuracy.The systematic search approach can be a new strategy to search supramolecular synthons and identify structures effectively and does have the potential to promote the develo
文摘目的全面分析细胞实验系统评价/Meta分析(SRs/MAs)检索策略的制定和报告现状,为后续相关研究的开展提供参考依据。方法计算机检索PubMed、CNKI和Wanfang Data,检索时限均为建库截至2017年10月。结果最终纳入细胞实验SRs/MAs共82篇,其中英文79篇,中文3篇。64.63%(53/82)的研究报告了文献筛选流程图,6.10%(5/82)报告了检索人员的资质,45.13%(37/82)报告了至少一个完整的检索策略。有18.29%(15/82)的细胞实验SRs/MAs仅检索了1个数据库,检索5个以上数据库的研究仅9.76%(8/82)。此外,有53.66%(44/82)和8.54%(7/82)的研究中分别进行了其他方法的补充检索和灰色文献检索。在检索方式上,以DI(疾病+干预措施)的方式最为常见。结论目前已发表的细胞实验SRs/MAs在检索策略制定和报告方面均存在一定局限性,并无共识标准或规范的方法。因此,今后的研究有必要:①在数据库的选择上,除检索PubMed、EMBASE外,应对Web of Science、Scoups等数据库也进行检索。此外,对于灰色文献的收集,包括会议资料等阴性结果或未发表研究的收集需要更加关注;②在细胞实验SRs/MAs检索词的选择方面,除涉及的细胞及其干预措施外,涉及到测量指标的检索词亦是重要的参考依据;③研发细胞实验SRs/MAs的报告规范,以提高其报告质量,包括提供至少一个数据库完整的检索策略、提高检索人员的资质等相关信息的报告度。
