Mode Choice in a Hub-and-Spoke Network: A Zero-One Linear Programming Approach

While research has tackled the hub-and-spoke network design problem, that research has overlooked the air-truck modal integration issue which is a common feature of real express delivery systems. This paper devises integer linear programs to represent the mode and route assignment aspects of the operational problem. The model is solved under four different levels of delivery schedule, and the results show that as the promised delivery schedule is relaxed, not only does the use of truck routes become more desirable, but also interesting adjustments in mode and hub assignment occur. Consider the case of hubs in Los Angeles and Dayton. As the time constraints are relaxed, cities such as Minneapolis and New Orleans originally linked by air to Los Angeles, switch to Dayton because cheaper truck routes become feasible.     

一种油画颜料层裂纹的修复技术分析

油画颜料层裂纹是一种常见的病害类型,严重的裂纹会影响作品的视觉效果。裂纹修复所采取的措施应以缓解病害,延续寿命为目标,避免不当修复对其文物价值的改变。本研究通过红外光谱和便携式X荧光能谱分析,初步确定了裂纹产生的原因与材料技法和机械作用力有关,长期的温湿度波动则是最终形成老化裂纹的重要因素。对两类常见的裂纹加固方法比较后得出结论,色蜡改变了原画的光泽度和肌理层,动物胶调碳酸钙更适宜作为裂纹的填补材料。观察修复后的油画保存状况,发现经过修复的颜料层仍存在继续劣化的风险,必须维持保存环境的相对稳定,方可延长修复周期。     

"承上制下"与"从左转右":北宋物资转输区域的互动——以东南地区为中心

北宋时期,朝廷在淮南地区运河沿岸州军设置转般仓,这些州军具有了转般粮食物资进京的功能;又先后置发运司于真州和泗州,使其开始具有总管东南漕运事务的职能;盐利也集中于此,同时亦掌控着地方物资的上供经费.其他物资转输区域则经常出现改变转运方式的情形,中转区域改变了起始区域输出物资的运输方式,减轻了部分运输成本.起始区域在加重中转区域负担的同时,亦对中转区域的经济繁荣有促进作用.     

Micro-CT-assisted determination of the shattering and non-shattering phenotypes of charred rice spikelet bases from archaeological sites: a new methodological approach

The selection of a non-shattering phenotype is a pivotal change in the process of rice domestication. However, current research is heavily restricted by the preservation conditions of macro-plant remains in early and middle Neolithic sites, as very limited well-preserved rice spikelet bases could be retrieved. We present a non-destructive method based on micro-computed tomographic (CT) scanning, which could provide detailed visualization of the internal structures of charred spikelet bases and efficiently discriminate the shattering and non-shattering phenotypes of rice spikelet bases according to the abundance of fusiform echinate phytoliths. It could be widely applied in different contexts, especially those poorly preserved specimens and tempers in pottery sherds, greatly improving our knowledge of rice domestication.     

张家界市博物馆明代铜佛像的多视角影像三维重建探索

由于多视角影像三维重建具有数据采集方便灵活、硬件成本低、操作简单、自动化程度高的特点,因此,选用多视角影像三维重建技术对张家界市博物馆明代铜佛像进行三维建模。通过描述佛像立面与空心底部的影像采集,再应用Agisoft PhotoScan软件进行三维重建的过程;从控制点的三维坐标与误差数值、模型成像与影像图的误差分析,得出佛像三维模型的精度误差微小的结论,证明该技术具有操作简单、模型成像清晰的特点。与三维激光扫描技术相比较,多视角影像三维重建技术具有成本费用低、工作流程高效简捷的优势,更适合在文物工作中推广运用。     

马家浜文化晚期陶鼎的兴起及其影响

环太湖地区马家浜文化晚期,形态各异的陶鼎开始兴起。各个类型陶鼎在时空分布、创制机理和发展过程等方面都存在着明显的不同,与本地区固有的以釜为主的炊器传统有着亲疏程度上的显著差异。不同制鼎传统之间彼此影响,关系错综复杂,一度形成了多个本土和外来传统并立的局面。厘清这些陶鼎类型的源流谱系,对于明确其后续影响,乃至阐释整个环太湖地区史前陶鼎传统的形成问题,都具有重要意义。     

AN ARTISTIC LIFE CREATED BY A PAIR OF SKILLFUL HANDS

正The cold season isjust about to arrive in Lhasa.A tallllbetan man is standing upon the golden roof of the Jokhang Temple to look out into distance.His name is Tsegya,a man with a deep affection for this very roof.This is the place where his karma connects him to his produced mandalas.Tsegya told me that     

基于GPS数据的北京郊区就业者工作与通勤行为特征研究——以上地信息产业园为例

城市空间快速扩张及郊区中心的崛起,带来多中心城市结构的演变及一系列城市问题。已有研究较少针对对郊区就业者的工作与通勤行为,未能全面地反映新职住“空间错位”。本文基于2012年对北京上地就业者的日常活动与出行调查数据得出以下结论：①主动郊区化的侧面通勤者体现出典型的郊区生活方式： “朝九晚六”、加班明显,生活活动空间更加广域化。②在郊区化过程中被动调整的逆通勤者职住距离最长、依赖公共交通通勤、“早出晚归”、错峰出行、生活活动空间呈现以家和工作地为主的“两极化”特征。③郊区中心内部相对职住接近的就地通勤者,在享受工作与通勤便利性（如职住接近、“晚出早归”）的同时活动空间高度隔离集中在郊区中心。