建筑隔震与分部设计法评述

房屋建筑采用隔震技术,可以显著降低建筑物的水平地震反应,实现更高的抗震目标。本文从工程设计的角度出发,结合《建筑抗震设计规范》中关于隔震设计的相关条款,对隔震建筑的减震原理、隔震技术应用范围、隔震设计基本要求、水平向减震系数和分部设计法等内容进行较为系统的论述,以期为设计人员把握隔震建筑设计脉络、掌握隔震设计方法提供帮...     

多口径钢管涡流探伤系统的研究与设计

该文针对实际生产过程中,钢管口径种类多的情况,研究设计了一种新型涡流探伤系统。该系统实现了自动化控制,操作安全可靠,生产效率高。适合Φ73～Φ340 mm口径钢管探伤工艺,具有广阔的推广应用前景。     

Static and fatigue design of CHS-to-RHS welded connections using a branch conversion method

This paper evaluates the hypothesis that welded hollow section connections, which have circular hollow section (CHS) branch (or bracing or web) members welded to a rectangular hollow section (RHS) chord member, may be converted into “equivalent” connections whereby the circular branch member is replaced by a square branch member. Although this notion has existed for the static design of such connections, its implementation into design recommendations or specifications has never been checked against existing test data. This is performed herein, using a database of gapped and overlapped CHS-to-RHS N-connection tests undertaken by others, and the suitability of this procedure is examined for both existing and proposed new static design recommendations for RHS welded connections. For fatigue design, no design guidance exists for CHS-to-RHS welded connections. Thus, a database of welded CHS-to-RHS T-connection fatigue tests, undertaken by both the authors and others, under branch axial loading or branch in-plane bending, is used to evaluate the replacement of the circular branch with an equivalent square branch, in the context of contemporary fatigue design procedures. It is shown that, for the connection types examined, this substitution of a circular branch member by an equivalent square branch member is a valid operation, with an adequate level of safety, for both the static and fatigue design of such connections. This indicates that existing design rules for planar RHS-to-RHS welded connections can likely suffice for the unusual case of CHS-to-RHS welded connections.     

Optimization of multiple-channel cooperative spectrum sensing with data fusion rule in cognitive radio networks

This paper focuses on multi-channel Cooperative Spectrum Sensing (CSS) where Secondary Users (SUs) are assigned to cooperatively sense multiple channels simultaneously. A multi-channel CSS optimization problem of joint spectrum sensing and SU assignment based on data fusion rule is formulated, which maximizes the total throughput of the Cognitive Radio Network (CRN) subject to the constraints of probabilities of detection and false alarm. To address the optimization problem, a Branch and Bound (BnB) algorithm and a greedy algorithm are proposed to obtain the optimal solutions. Simulation results are presented to demonstrate the effectiveness of our proposed algorithms and show that the throughput improvement is achieved through the joint design. It is also shown that the greedy algorithm with a low complexity achieves the comparable performance to the exhaustive algorithm.     

Spread time considerations in operational fixed job scheduling

In this study, we consider the operational fixed job scheduling problem on identical parallel machines. We assume that the jobs have fixed ready times and deadlines, and spread time constraints are imposed on machines. Our objective is to select a set of jobs for processing so as to maximise the total weight. We show that the problem is strongly NP-hard, and we investigate several special polynomially solvable cases. We propose a branch and bound algorithm that employs size reduction mechanisms, dominance conditions, and powerful lower and upper bounds. The computational results reveal that the branch and bound algorithm returns optimal solutions for problem instances with up to 100 jobs in reasonable solution times.     

大清河北支山区地表径流锐减原因分析与计算

利用有序聚类分析法对大清河北支山区径流系列进行检验,1979年是地表径流系列过程发生显著突变点。用F检验法对突变点前后系列进行一致性检验,两个时段的径流系列差异显著。由此认为1979年以后径流量受人类活动影响显著。通过对影响径流量的人类活动因素和降水量因素进行分析计算,人类活动对径流量的影响范围在25％～40％之间;降水量减少对径流量的影响范围在25％～50％之间。由此可认为,该流域径流量减少的主要原因是降水量减少。通过对地表径流锐减的原因分析与计算,为今后制定水资源开发利用方案提供科学依据。     

正反浮选分支精选工艺在大峪口胶磷矿的工业化应用实践

大峪口胶磷矿浮选工艺为正反浮选工艺流程,正浮选工艺采用脂肪类捕收剂进行加温浮选,该工艺存在中间产品,作业产率高、粗选泡沫体积大、后续作业浮选机输送载矿泡沫能力不足、精矿泡沫外溢、浮选作业指标波动较大等问题,导致系统实际生产能力只达到设计能力的80％.针对该问题,提出了正反浮选分支精选工艺流程,并对原生产工艺和设备布置进...