Teams as boundaries: How intra‐team and inter‐team brokerage influence network changes in knowledge‐seeking networks

What role does an ego's brokerage location—within a team (intra‐team) or outside the team (inter‐team)—play in the evolution of an instrumental knowledge‐seeking network in terms of both proximal (i.e., within the team) and distal (i.e., outside the team) tie formation and tie decay? We address this question by drawing on literature about social networks, brokerage, and teams. We use temporally separated data from 302 students embedded in 97 teams to test our hypotheses about the impacts of intra‐team and inter‐team brokerage on proximal and distal network evolution, specifically on four network changes in knowledge‐seeking networks: proximal tie formation, proximal tie decay, distal tie formation, and distal tie decay. We find that these four changes depend on individual network brokerage location even after controlling for personality and task characteristics. Specifically, inter‐team brokers change their networks both within and outside their teams, whereas intra‐team brokers curtail their network changes. We argue that these opposite effects occur because inter‐team brokers have greater autonomy than intra‐team brokers. This study adds to the ongoing dialog about network evolution in social network literature and to the conversations about brokerage and its location in the context of team‐based work.     

南京地区农业资源的综合评价研究

客观、准确地评价地区农业资源,对于农业资源的开发和利用具有重要意义。本文从系统论观点出发,将地区农业资源分成自然资源和社会资源,在能够较好地反映系统结构特征、不同样点差异及满足易于收集、便于数量表示和定量处理等基本要求的基础上,选择了若干评价指标。利用综合指数法、区位商法等评价方法,对南京地区的主要农业资源（土地资源、气候资源与社会资源）进行了定量分析,并在此基础上,利用资源优势度分析法进行了综合评价。结果表明,南部小区的农业资源具有整体优势,南部和中部的资源利用较为合理,北部小区则具有较为丰富的后备资源。最后,根据各地资源要素的不同组合,简要给出了较适宜的开发途径,为该地农业资源的进一步开发与利用提供了依据。     

蜂窝断面内循环三相生物流化床内流动状况的数值模拟

根据蜂窝断面内循环三相生物流化床内混合液的连续性方程、动量方程和能量方程,利用Fluent软件对反应器内的流动状况进行了数值模拟.采用Fluent的前处理软件Gambit完成流化床的三维模型,利用Fluent主程序解析计算,并利用后处理软件实现计算结果的显示.模拟计算结果获得了反应器内静压力、静压差的变化规律,得到了液体循环速度、气含率沿纵向及横断面的分布.     

立井揭煤前测定煤层瓦斯压力的方法与实践

为了解决复杂环境下立井揭煤前煤层瓦斯压力的可靠测定,基于揭煤井筒瓦斯地质特征、煤岩体物理力学性质,应用COMSOL软件模拟揭煤工作面在接近目标煤层时,井筒周围煤岩的地应力分布特征,直观展现了目标煤层中的应力分布结果。模拟结果表明,立井工作面距煤层的垂直距离为7 m时,煤层中会形成一个近似于环形的卸压圈,卸压半径为16 m,因此煤层瓦斯压力测试孔的终孔位置应布置在井筒中心线16 m以外的原始地应力区,以保证测压点瓦斯压力不受揭煤井筒卸压区的影响,令测压结果准确可靠,从而更好地预测煤与瓦斯突出区域的危险性。同时,结合立井揭煤工作面的水文地质特征和井筒严重淋水情况,自主研发并应用了瓦斯测压孔"两堵一注"封孔材料及特定的封孔工艺,进一步保障了封孔质量和瓦斯压力测试结果的可靠性。最后,依据测压结束时测压管内的实际水压情况,对测压结果进行修正,并依据实测瓦斯含量,采用间接法对所测得的瓦斯压力进行验证,实测值在反算得到的瓦斯压力值域内,表明此方法有效可行。     

优化模型在污泥处理厂选址中的应用

在我国大中城市,污水处理厂的不断兴建使污泥处理问题应运而生。采用混合整数优化模型可以解决污泥处理厂的科学选址问题,达到科学布点、合理运输、节省投资费用的目的。在传统厂群规划模型的基础上将目标规划、周密的约束条件等融于其中,并采用对于线形规划和非线性规划问题适用的LINGO软件进行求解。根据东莞市拟建的36个污水处理厂污泥产生预测情况,对污泥处理厂的设置进行了分析预测,详细对比了建一个、两个、三个污泥处理厂的运输费用、投资费用、运行费用等,最终确定兴建两个规模均为800t/d的处理厂,其位置分别位于东莞市厚街镇和常平镇,为厂址选择和规模提供了科学依据和保障。     

The method for leakage detection of urban natural gas pipeline based on the improved ITA and ALO

To solve the problems of the difficulty in early leakage monitoring and larger positioning error for urban hazardous chemicals pipelines, the optimized method based on the improved Inverse Transient Analysis (ITA) and Ant Lion Optimizer (ALO) was proposed. Firstly, based on the obtained experiment's results of leakage of natural gas in the non-metallic pipeline, the segment classification method was incorporated into the pressure gradient calculation. The modified method can adapt to the multi-node characteristics of urban pipe networks and help to obtain the preliminary positioning calculation results after optimization. Then the calculation results were embedded in the ITA calculation model. The input parameters of the gas pipeline such as boundary conditions, leakage rate and friction coefficient were used to establish the characteristic linear equations. Then the objective function of the least-squares criterion was defined, and the improved ITA model suitable for leakage detection of urban natural gas pipeline networks was constructed. Finally, the ALO was used to optimize the calculation process of the improved ITA model, and iteratively optimize the optimal friction coefficient and its corresponding minimum objective function (OF) value. As a result, a more precise location of the leakage source was calculated. The validation of the modified method is conducted by comparing the calculated values with the experiment's results. The results show that the method can accurately predict the location where the pipeline leakage occurs. The minimum error is 3.17%. Compared with the traditional ITA, this method not only accelerates the convergence speed of the objective function, but also improves the accuracy of location calculation.     

海岸带及其调查技术进展

海岸带是重要海陆过渡带地貌单元与区域,兼受海陆动力双重作用与影响,包括不同类型的沉积相,经历复杂的动力沉积、地貌演变及灾变过程。海岸带调查涉及学科交叉融合,调查要素相对独立与内容多学科交叉并存。我国曾分别于1960年、1981年和2003年组织开展过全国海岸带综合调查工作,调查获取了大量丰硕成果。当前海岸带调查与研究过程中亦暴露出一些亟需突破问题,包括:1)海岸带存在大范围“盲区”,浅水易陷、礁石养殖等区域难以到达,成为海岸带数据“空白区”、调查“禁区”;2)我国海岸带观测平台数量少、分布零散,未形成综合有效观测网,导致长时间序列、多源准同步调查数据缺乏,难以准确把握海岸带变化规律,破解资源环境有关问题;3)海岸带数据获取智能化程度低,严重阻碍制约有关对策及时有效性;4)海岸带不同学科协同调查、交叉融合研究模式尚未建立,不能及时发现海岸带科学问题。今后海岸带调查将在海岸带高分辨率过程数据、全覆盖无死角实时动态数据获取技术,长时间序列综合数据采集平台建设,陆海空全天候立体化数据采集传输及快速智能决策,以及海岸带多学科交叉攻关研究等方面取得突破。     

卫星遥感技术在空气点位布设评估工作中的应用研究

以苏州市为例,利用2013-2014年MODIS高分辨率大气气溶胶卫星遥感产品对国控空气监测点位布设调整方案进行评估论证,通过提取2 km和5km半径范围的PM2.5遥感观测数据,与现有国控布设点位的地面监测数据进行相关性分析后,确定卫星产品用于评估验证是可靠的;通过不同天气场下PM2.5月均值浓度分布的比较,表明调整后空气点位布设具有很好的代表性.     

S型皮托管截面受损与皮托管系数变化的实验研究

污染源排放废气流速通常在7～15m／s之间。通过S型皮托管在低速风洞中与标准皮托管的对比实验说明,在10m／s,15m／s两种情况下,皮托管迎风面截面变化对皮托管系数却的影响很大,实验结果可供污染源废气监测和皮托管定期检定进行参考。     

震前小震调制比空间异常消失的映震能力研究

利用小震调制比方法的时空异常进行跟踪分析,通过对比发现,近几年震前小震调制比的空间异常变化与有感地震的发生具有一定的对应关系.进一步的分析研究认为,利用震前小震调制比的空间异常消失可进行有感地震甚至中强地震的地点预测.