Shaking table tests on seismic measures of a model mountain tunnel

A series of three dimensional (3D) shaking table tests were carried out to investigate the mechanism and effect of seismic measures of mountain tunnel using a scaled model based on a real tunnel. Key technical details of the experiment, including similarity relations, seismic measures simulation, boundary conditions, sensor layout, modeling methods, and ground motion input were presented. Main seismic measures, including reinforcing surrounding rock with anchors, increasing lining flexibility with steel wire mesh, and installing seismic isolation layer between reinforced surrounding rock and tunnel lining, were investigated in this study. Experiment results show that: (1) adding a layer of steel wire mesh in the tunnel lining can improve the flexibility and seismic performance and also may effectively prevent radial cracks from crossing the lining; (2) installing a geofoam isolation layer between the reinforced surrounding rock and the tunnel lining reduces dynamic earth pressure by 70–90% for the lining without a seismic isolation layer; (3) the flexible joints can effectively avoid global failures of tunnel lining for they reduce dynamic strain and bending force in the tunnel lining and decrease the seismic energy transmission along the lining in axial direction; (4) reinforcing surrounding rock with anchors significantly reduces dynamic earth pressure and strain of the lining by about 50%. In addition, the length of seismic reinforcement for general mountain tunnel portal is recommended to be 50 m from the tunnel portal along the axial direction.     

Bars on blocks: A cellular automata model of crime and liquor licensed establishment density

Criminologists have extensively researched the problems generated by licensed establishments. Violent offending and disorderly behavior resulting from pubs, taverns, dance clubs and bars are of particular interest to this field of study. The relative density of these liquor establishments has been found to be associated with the level of violence and disorder in surrounding areas. A complex systems approach can be used to further understand the dynamic interplay between licensed establishments, violent offending and disorder, and urban planning decisions. The model presented here utilizes cellular automata as the mathematical framework to view the varying impact of liquor licensing density on crime. This study uses a sample of liquor establishments and crime data from the City of Vancouver in British Columbia. The cellular automata model incorporates transition rules which govern the change of city blocks from low-risk blocks to high-risk blocks. The results represented by a 50 × 50 cellular grid show that high-risk blocks multiply when liquor licenses are grouped. Two scenarios are presented to contrast the impact of grouping high-risk blocks which contain more liquor establishments and dispersing such blocks. A third scenario demonstrates how increasing the positive influence in a grouped scenario stops high-risk blocks from taking over the entire grid. Future iterations of this model will incorporate census data, public transportation data, land use data and entertainment districts from other cities to further analyze the effect of licensed establishments on the distribution of crime.     

Incorporation of extended neighborhood mechanisms and its impact on urban land-use cellular automata simulations

Urban cellular automata (CA) models are broadly used in quantitative analyses and predictions of urban land-use dynamics. However, most urban CA developed with neighborhood rules consider only a small neighborhood scope under a specific spatial resolution. Here, we quantify neighborhood effects in a relatively large cellular space and analyze their role in the performance of an urban land use model. The extracted neighborhood rules were integrated into a commonly used logistic regression urban CA model (Logistic-CA), resulting in a large neighborhood urban land use model (Logistic-LNCA). Land-use simulations with both models were evaluated with urban expansion data in Xiamen City, China. Simulations with the Logistic-LNCA model raised the accuracies of built-up land by 3.0%–3.9% in two simulation periods compared with the Logistic-CA model with a 3 × 3 kernel. Parameter sensitivity analysis indicated that there was an optimal large window size in cellular space and a corresponding optimal parameter configuration.     

规划动态性特征分析及其在城市设计中的应用——以聊城市徒骇河两岸规划发展为例

城市功能交界区是城市一体化发展的重点区域,而城市中央滨水区域则是城市"都市生活"的核心区域。在功能交界区的滨水地带向中央滨水区过渡的过程中,滨水区域凭借便利的交通及优越的自然环境,往往成为城市功能角色转变中最大的区域,也是城市规划管理中最具动态性、最难控制的区域。研究以聊城市徒骇河两岸近十年的规划发展为例,分析规划动态性的成因,探究规划动态管理在城市设计中的应用,为规划编制和规划管理提供借鉴与参考。     

A microsimulation model of urban energy use: Modelling residential space heating demand in ILUTE

Rapid urbanization, climate change and energy security warrant a more detailed understanding of how cities today consume energy. Agent-based, integrated microsimulation models of urban systems provide an excellent platform to accomplish this task, as they can capture both the short- and long-term decisions of firms and households which directly affect urban energy consumption. This paper presents the current effort towards developing an urban energy model for the Integrated Land Use, Transportation, Environment (ILUTE) modelling system.     

Urban navigation beyond shortest route: The case of safe paths

Advancements in mobile technology and computing have fostered the collection of a large number of civic datasets that capture the pulse of urban life. Furthermore, the open government and data initiative has led many local authorities to make these datasets publicly available, hoping to drive innovation that will further improve the quality of life for the city-dwellers. In this paper, we develop a novel application that utilizes crime data to provide safe urban navigation. Specifically, using crime data from Chicago and Philadelphia we develop a risk model for their street urban network, which allows us to estimate the relative probability of a crime on any road segment. Given such model we define two variants of the SafePaths problem where the goal is to find a short and low-risk path between a source and a destination location. Since both the length and the risk of the path are equally important but cannot be combined into a single objective, we approach the urban-navigation problem as a biobjective shortest path problem. Our algorithms aim to output a small set of paths that provide tradeoffs between distance and safety. Our experiments demonstrate the efficacy of our algorithms and their practical applicability.     

基于传统街区更新的城市设计

以南京市小西湖地块为例，深入探 讨城市设计在传统街区城市更新中的基础、 角色、手段及成果形式。以提高市民的生活 品质、提高容积率、保护历史地段结构和提 升公共空间品质为目标，本着社会公平立场、 城市记忆立场与城市传统街区风貌保护的立 场，通过基于历史成因的和基于整体市民利 益的两种分配方式，城市设计最终认可城市 形态动态变化的合理性、扩大居民/市民/游 人共享的公共空间、实现居民与建设主体多 方获益。     

Are HFC buses a feasible alternative for urban transportation in Paraguay?

Paraguay is very rich in hydropower and a net importer of fossil fuels. Besides, in Paraguay, the transportation sector counts for a big share of the total energy demand. So if this sector would be changed to clean fuel, imported oil dependence and air pollution will be reduced dramatically. This paper assesses the feasibility of HFC urban buses implementation in the transportation sector in Paraguay. In general, annual transportation cost for a fleet of 55 HFC urban buses is estimated in US$ 33,682,581 compared with US$ 40,612,741.84 for diesel urban buses, which indicates that this technology could be an economical and environmentally clean alternative to substitute diesel urban buses in the Paraguayan transportation sector. These results are strongly linked to the chosen boundary conditions, such as electricity price and availability, the electrolytic hydrogen demand and the basic electrolyser's management.     

Solar potential in existing urban layouts—Critical overview of the existing building stock in Slovenian context

In recent years implementation of sustainable building design in the EU has become one of the key issues in reducing energy dependence. In this context efficient use of solar potential incident on building envelope is essential. The goal of the study is to evaluate the influence of interventions required by the new Slovenian legislation and to propose general site planning guidelines. Special emphasis is devoted to the existing building stock, which is due for refurbishment. The study is carried out on the basis of seven typical urban layouts, which are assessed according to the shape of layout, density, building orientation and design. The calculations are carried out with the program SHADING. The study showed that the existing layouts are not as problematic as had been expected and that form and orientation of buildings present a major challenge. Nevertheless, the quality and the duration of insolation are highly dependent on the specifics of each case. The study showed that by respecting the basic rules of good practice in conjunction with the existing requirements no major changes in the existing design principles are needed.