Beyond absolute space: An exploration of relative and relational space in Shanghai using taxi trajectory data

The nature of urban space has long-drawn geographers' interest and David Harvey's conceptual framework of multiple spaces (i.e., absolute, relative, and relational) within cities has been widely adopted and developed. With its high spatial and temporal resolution, geospatial big data plays an increasingly important role in our understanding of urban structure. Taxi trajectory data is particularly useful in travel purpose estimation and allows for more granular insights into urban mobility due to the door-to-door nature of these trips. This article utilizes taxi trajectory data and explores the interaction among absolute space, relative space, and relational space in Harvey's framework using Structural Equation Modeling (SEM). Through an empirical study of Shanghai's downtown area, this paper highlights the importance of Harvey's framework in understanding cities' dynamic structure and argues for changes in urban planning and development to better coordinate land use and travel demand. We find an insignificant relationship between relative and relational space in Shanghai due to a mismatch between urban mobility and the built environment. This mismatch concentrates the transportation flow near the city's core area, transforming the polycentric structure of Shanghai's built environment in absolute space to a single-node structure in relational space. After identifying the contributing factors to this problem in Shanghai, this article suggests combining Harvey's conceptual framework of multiple spaces with geospatial big data to inform planning strategies that address the challenges of rapid urbanization.     

“Switching is easy”—Service firm communications to encourage customer switching

For several service industries, customer acquisition is challenged because of matured markets. Winning new customers typically means encouraging the competitors׳ customers to switch. This article analyzes “Switching is easy”-messages of retail banks. In their marketing communication, UK banks focus on several aspects to decrease perceived switching costs of their competitor customers. However, many facets stay unmentioned such as stress-related dimensions of switching a relationship. The study therefore contributes to service research by outlining how service firms focus on to decrease perceived switching costs of bank customers to acquire them from competitors.     

Revealing intra-urban travel patterns and service ranges from taxi trajectories

As an important transport tool, taxi plays a significant role to meet travel demand in urban city. Understanding the travel patterns of taxis is important for addressing many urban sustainability challenges. Previous research has primarily focused on examining the statistical properties of taxi trips to characterize travel patterns, while it may be more appropriate to explore taxi service strategies on seasonal, weekly or daily time scale. Therefore, intra-urban taxi mobility is investigated by examining taxi trajectory data that were collected in Harbin, China, while 12-week corresponding to 12-month is chosen as the sampling period in our study. The multivariate spatial point pattern analysis is firstly adopted to characterize and model the spatial dependence, and infer significant positive spatial relationships between the picked up points (PUPs) and the dropped off points (DOPs). Secondly, the points of interest (POIs) are identified from DOPs using the emerging hot spot detection technique, then the taxi services and movement patterns surrounding POIs are further examined in details. Moreover, our study builds on and extends the existing work to examine the statistical regularities of trip distances, and we also validate and quantify the impacts posed by airport trips on the distance distributions. Finally, the movement-based kernel density estimation (MKDE) method is proposed to estimate taxis' service ranges within three isopleth levels (50, 75 and 95%) between summer/weekday and winter/weekend from taxi driver's perspective, and season as well as temperature factors are identified as the significant effect within certain service range levels. These results are expected to enhance current urban mobility research and suggest some interesting avenues for future research.     

Connectivity to international markets: A multi-layered network approach

Improving connectivity for freight movements between countries is increasingly a topic at the centre of the international trade and transport policy agendas. In spite of this, a method to asses a country's degree of connectivity to its international markets for freight is still missing. To close this gap, this paper proposes a multi-layered network approach that enables the assessment of: (i) the different factors that influence connectivity to international markets; and (ii) the extent to which a country's connections matter for its international trade activities. The international trade network and its ‘support network’ are analysed using network theory. The approach proposed is applied to the Americas, a region the relevant literature has not specifically focused on yet. It is expected that a comprehensive understanding and assessment of the determinants of connectivity for freight will contribute to guide and design more effective policies to remove barriers to international trade flows.     

两种工艺对玉米皮中α-纤维素提取的研究

以玉米皮为原料提取α-纤维素,采用传统α-纤维素制备工艺和超声波辅助工艺进行比较优化,经研究表明,NaOH水溶液是最佳提取剂,传统工艺提取α-纤维素的最佳参数为:提取剂浓度11%,物料比1∶13,温度70℃,提取时间80 min。在此工艺条件下,α-纤维素的提取率为33.70%。通过正交试验设计,超声波提取α-纤维素的最佳工艺为:提取剂浓度13%,物料比1∶13,温度90℃,提取时间40 min,超声波功率500 W,α-纤维素的提取率44.96%。     

Minimising the harm to biodiversity of producing more food globally

Should farming and conservation policies aim broadly to separate land for nature and land for production (land sparing) or integrate production and conservation on the same land (wildlife-friendly farming)? Most studies that try to address this question suffer from flaws in sampling design, inappropriate metrics, and/or failure to measure biodiversity baselines. We discuss how these failings can be addressed, and what existing information tells us about the key debates on this topic. The evidence available suggests that trade-offs between biodiversity and yield are prevalent. While there are some wildlife-friendly farming systems that support high species richness, a large proportion of wild species cannot survive in even the most benign farming systems. To conserve those species, protection of wild lands will remain essential. Sustainable intensification could help to facilitate sparing of such lands, provided that as much attention is given to protecting habitats as to raising yields. We discuss the general circumstances under which yield increases can facilitate land sparing, recognising that policies and social safeguards will need to be context-specific. In some situations, bringing degraded lands into production could help reduce pressure on wild lands, but much more information is needed on the biodiversity implications of using degraded lands. We conclude that restricting human requirements for land globally will be important in limiting the impacts on biodiversity of increasing food production. To achieve this, society will need to integrate explicit conservation objectives into local, regional and international policies affecting the food system.     

无纸化考试的应用现状及前景分析

无纸化考试是信息时代计算机的一个重要应用。无纸化考试可以极大地提高考试的灵活性、科学性、公正性、和工作效率。本文概括介绍了无纸化考试应用现状,并对其应用前景进行了分析。     

佳木斯市土地整治规划资金测算实证研究

土地整治资金是土地整治工作顺利开展的重要保障。以佳木斯市土地整治规划方案为基础,采用单位面积标准投资估算土地资金需求,测算近几年已实施的不同地貌类、不同整治类型的整治项目投资情况,对投资标准进行修正后乘以规划方案确定的整治规模,得出规划期内需求土地整治资金;通过新增建设用地土地有偿使用费、耕地开垦费、土地出让金用于农业土地开发资金、土地复垦费、其他投资等渠道测算供给土地整治资金。佳木斯市基本上能够达到土地整治资金供需平衡,筹资力度的大小将是规划方案成功实施的关键所在。     

稀薄气体中高超速圆柱绕流仿真研究

高速尤其是高超音速飞行是航空航天发展的主流方向．目前,70km以上高超音速飞行器的需求越来越大．当飞行高度达到或超过70km时,稀薄效应明显,此时连续介质假设失效,传统的连续流体运动方程（NS方程）和相应的CFD方法已经失效．利用连续流体运动方程（NS方程）和直接模拟蒙特卡洛方法（DSMC）,对四个典型K（K分别为0．001、0．01、0．1和1）下的圆柱绕流进行了计算．分析比较发现,随着K的增大,流场中的激波间断结构变弱变粗,甚至消失,圆柱后方的分离区也逐渐变小直到消失．     

大米蛋白对幼鼠血脂及脂质代谢调控因子基因表达水平的影响

为了探讨大米蛋白对生长期幼鼠血脂水平及脂质代谢相关因子的调控作用,分别给雄性Wistar 7周龄幼鼠饲喂添加1%胆固醇及0.25%胆酸钠的大米蛋白及酪蛋白(粗蛋白含量为20%),自由摄食3周后,测定实验鼠血浆总胆固醇、血浆高密度脂蛋白胆固醇、血浆三酰甘油水平及肝脏3-羟基-3甲基-戊二酰CoA还原酶(HMG-CoA R)、乙酰辅酶A乙酰基转移酶2(ACAT2)、固醇调节元件结合蛋白-1(SREBP-1)的基因表达水平。对照酪蛋白,大米蛋白显著降低幼鼠血浆总胆固醇、血浆非高密度脂蛋白胆固醇、血浆三酰甘油水平,并且显著降低了肝脏HMG-CoA R、ACAT2、SREBP-1的基因表达水平。实验结果表明,大米蛋白具有降低幼鼠血脂水平的功效,其主要作用机制之一是抑制其脂质合成与吸收。