A Hybrid AL-Based System for Site Layout Planning in Construction

The layout of temporary facilities on a construction site is a complex and experience-based process that aims at minimizing the travel distance among facilities and improving site productivity and safety. To address the difficulties associated with the process, this article presents a hybrid system for construction-site layout planning. The originality of the proposed system stems from its integration of three components, each is developed based on a different artificial intelligence (AI)–based technique: (1) a knowledge base that stores and uses information related to identifying necessary facilities and their sizes, (2) a fuzzy quantifier to address the vagueness inherent in the project manager's assessment of facilities' closeness relationships, and (3) an improved genetic algorithm to search for an optimal layout solution. Details of the system are described, and a case study is used to demonstrate its capabilities. Possible extensions are then outlined.     

Removal of bulk dissolved organic carbon (DOC) and trace organic compounds by bank filtration and artificial recharge

Bank filtration and artificial recharge provide an important drinking water source to the city of Berlin. Due to the practice of water recycling through a semi-closed urban water cycle, the introduction of effluent organic matter (EfOM) and persistent trace organic pollutants in the drinking water is of potential concern. In the work reported herein, the research objectives are to study the removal of bulk and trace organics at bank filtration and artificial recharge sites and to assess important factors of influence for the Berlin area. The monthly analytical program is comprised of dissolved organic carbon (DOC), UV absorbance (UVA254), liquid chromatography with organic carbon detection (LC-OCD), differentiated adsorbable organic halogens (AOX) and single organic compound analysis of a few model compounds. More than 1 year of monitoring was conducted on observation wells located along the flowpaths of the infiltrating water at two field sites that have different characteristics regarding redox conditions, travel time, and travel distance. Two transects are highlighted: one associated with a bank filtration site dominated by anoxic/anaerobic conditions with a travel time of up to 4-5 months, and another with an artificial recharge site dominated by aerobic conditions with a travel time of up to 50 days. It was found that redox conditions and travel time significantly influence the DOC degradation kinetics and the efficiency of AOX and trace compound removal.     

A fuzzy based multi-objective path planning of construction sites

Movement of materials, plant and site operative from one place to another on construction sites and construction workplaces are of paramount importance to site planners as savings in travel distance can reduce cost and increase productivity. In addition, risks on construction sites can be reduced if the use of vehicles and mobile plant is properly managed by setting out paths avoiding high risks areas. The work reported in this paper presents a framework for supporting path planning analysis of construction sites based on multi-objective evaluation of transport cost, safety, and visibility. This paper investigates the use of fuzzy-based multi-objective optimisation approach in making a more informed strategic decisions regarding the movement path of people and vehicles on construction sites, and detailed decisions regarding travel distance and operational paths on workplaces, enabling site planners to examine paths scenarios that are subjected to a high degree of uncertainty and subjectivity.     

Exploring the spatial arrangement of patient rooms for minimum nurse travel in hospital nursing units in Korea

With increasing demands on medical care services, one of the trends is the mixed patient room arrangement of single/double-bed and multi-bed rooms in a nursing unit on the same floor. This influences nurse-to-patient assignment and often causes an unbalanced workload and longer travel distances for nurses. The objective of this study was to investigate how floor configuration and room density influence nurse travel in the hospital's medical surgical units in Korea. This study presented a novel approach to measure nurse travel distances in eight existing nursing units. The agent-based simulation was conducted to model nurses' walking trails, and the distance of one nurse travel to assigned patient rooms was measured for each nurse. With revisions in the spatial arrangement of patient rooms, locating multi-bed rooms near the nurse station, symmetric room layout centering the nurse station, and planning both single/double-bed and multi-bed rooms on one side of corridors, nurse travel distance decreased more than 15%. This study contributed to the knowledge of agent-based simulation as an evaluation framework for spatial analysis. Apart from application to Korea, these results are particularly of interest in countries where private patient rooms are not commonly economically feasible.     

基于YOLOv5算法的施工现场不安全状态智能检测

为更好地实现施工现场工人的安全监管,利用YOLOv5目标识别算法结合无人机倾斜摄影三维建模技术构建施工现场不安全状态智能检测模型,实现对人、机械等目标的识别与定位。通过实验对比分析确定最优目标识别算法,并构建多目标识别模型,实验结果符合理论猜想,整体识别平均精度达到了91.6%。在识别的基础上借助倾斜摄影三维模型所提供的空间位置信息进一步确定所识别目标的相对位置,从而确定工人的安全状态。这种视觉定位的准确性由三维模型所决定,所以最后通过实验验证了无人机倾斜摄影所构建的三维模型的距离误差在1.5% 左右,范围长度大于35m距离误差将小于1%,从而说明了目标识别模型所识别出物体的距离具有较高的准确性。     

Developing empirical relationships to predict loess slide travel distances: a case study on the Loess Plateau in China

To improve landslide hazard mapping quality, a functional relationship with travel distance prediction is essential. To obtain a more accurate empirical relationship for predicting loess slide travel distances, we developed a loess slide database for the central Loess Plateau using a combination of remote sensing image interpretations, existing datasets, and an intensive field survey. The loess slide travel distance was concentrated within less than 200 m, according to a cumulative frequency analysis. Our results reveal that the loess slide volume, slope height, and slope inclination of the sliding area control the travel distance, and this relation is well-described by a power law function. Furthermore, statistical analysis suggested that the equivalent coefficient of friction decreases with an increase in loess slide volume but increases with an increase in slope inclination. We compared the prediction performances of four empirical relationships proposed in this study using the mean absolute percentage error and Theil inequality coefficient methods. We discovered that the empirical relationship with three independent variables can more accurately predict the loess slide travel distance than the relationships with one or two independent variables.     

A compromise programming model for site selection of borrow pits

Road fill construction requires soil for filling low areas; this soil is obtained from temporary mineral workings known as ‘borrow pits’ (BP). Between a number of possible BPs, the appropriate site should be selected based upon conflicting econo‐technical and environmental criteria aiming at achieving optimal BP performance while minimizing the adverse impacts to human and natural resources. For solving this problem a model for BP selection has been developed by this research using compromise programming (CP). The model incorporates a hierarchical structure integrating criteria and sub‐criteria whose relative importance is set by the decision makers. Possible alternative BP sites are subsequently assessed on all these sub‐criteria. Based upon this analysis, the model determines the distance of each of the possible alternatives from the utopia (ideal) point; the option with the minimum distance is considered the best compromise. The relevant concepts are exemplified through the presentation of a case study concerning the BP site selection for an Egnatia Motorway section in northwest Greece. The main conclusion that can be drawn from this work is that the CP approach is appropriate and valid for BP selection and, furthermore, it may also be used for other multiple objective construction‐related site selection problems.     

A model used in creating a work-rest schedule for laborers

This paper presents a theoretical model that can be used to create work-rest schedules for construction workers. Two objectives are proposed in the optimization processes when such schedules are created. These objectives include minimizing the time for completing jobs and minimizing any extra energy expended by laborers due to inappropriate work assignments that force them to work longer than the maximum acceptable work duration. A GA-based mechanism was developed to search the Pareto front, which is one of the effective ways for solving multiobjective optimization problems. Such a mechanism was implemented by computer programming using a numerical software tool called MATLAB. Theoretical examples demonstrated that the proposed model efficiently created work-rest schedules.     

Job-Employed Resident Imbalance and Travel Time in Gauteng: Exploring the Determinants of Longer Travel Time

In the Gauteng City Region, a substantial number of workers reside far from their place of work, translating into long travel distances and high travel costs and time costs. This study examines the relationship between job-employed ratio, i.e. the percentage of residents that work in the same location in which they live, and average travel times. It also compares the average travel time between internal capture workers, who work and reside in the same area, with employment leakage workers, who work in areas other than those they reside in, and analyses other factors that influence average travel times. The ANOVA results reveal that job-rich and balanced areas are associated with higher average travel times for workers in housing-rich areas. Internal capture workers had the lower average travel time compared employment leakage workers. The regression results indicate that male gender, age and Black African ethnicity are positively associated with higher mean average travel time. Income, education level, informality and private transportation modes are negatively correlated with mean average travel time. This finding implies that land-use planning and public transport policies should be integrated to reduce travel time to work in the Gauteng City Region.     

Layout optimization of construction site facilities with dynamic freeform geometric representations

Traditional approaches to the construction site layout problem have been focused mainly on rectilinear and simple interpolated static geometrical shapes for modeling site facilities. Moreover, they have used proximity measures based on Cartesian distances between the centroids of the facilities. This is a fair abstraction of the problem; however it ignores the fact that many facilities on the construction sites assume non-rectilinear shapes that allow for better compaction within congested sites. The main focus of this research is to develop a new approach of modeling site facilities to overcome limitations and inefficiencies of previous models and to ensure a more realistic approach to construction site layout problems. A site layout optimization model was developed through a series of new algorithms for modeling regular and irregular freeform shapes of site facilities. The model mimics the “dynamic” behavior of the geometries of site facilities; where the geometrical shapes automatically modify their forms to fit in congested areas. Moreover, new proximity measures and distance measurement techniques were introduced. Furthermore, the research introduced the concept of selective zoning that significantly enhances optimization efficiency by minimizing the number of solutions through selection of pre-determined movement zones on site. At the end, a real site layout planning problem was solved using the developed model and the results were compared to two past models from the literature. The model has shown to be superior to the past models in optimizing congested and geometrically-complex site layouts.     

The application of the ant colony optimization algorithm to the construction site layout planning problem

A good site layout is vital to ensure the safety of the working environment, and for effective and efficient operations. Moreover, it minimizes travel distance, decreases materials handling, and avoids the obstruction of materials and plant movement. Based on studies in the manufacturing industry, the cost of materials handling could be reduced by 20–60% if an appropriate facility layout is adopted. In designing a site layout, a planner will first position the key facilities that influence the method and sequence of construction, and then assign the remaining facilities in the available space that is left over. This process is similar to the positioning of facilities in the ant colony optimization (ACO) algorithm. The general principle of the ACO algorithm is to assign facilities to a location one by one, and the occupied locations are deleted from the location scope in the next assignment. In the study, ACO algorithm is employed to resolve the construction site layout planning problem in a hypothetical medium‐sized construction project. By applying fuzzy reasoning and the entropy technique, the study calculates the closeness relationship between facilities, in which the optimal site layout is affected by the mutual interaction of facilities.     

EFFECTS OF CHANGES IN TRANSPORTATION AND PRODUCTION TECHNOLOGY AND CUSTOMER BEHAVIOR ON THE SIZE AND MARKET AREA OF URBAN ESTABLISHMENTS

ABSTRACT This paper develops a model to examine how the size of urban public establishments is affected by changes in transportation and production technology and customer behaviour. The size and market area are determined by minimizing the sum of average travel cost and average production cost, subject to demand-supply and revenue-cost equalities. The results show that improved transportation technology and reduced transportation cost have the effect of enlarging the size and market area, and the extent of this depends on the customers sensitivity to travel time. The effects of raised factor prices in production depend on the elasticity of the customer's demand with respect to the produced price.     

On the relationship between travel time and travel distance of commuters

This paper gives a detailed empirical analysis of the relationships between different indicators of costs of commuting trips by car: difference as the crow flies, shortest travel time according to route planner, corresponding travel distance, and reported travel time. Reported travel times are usually rounded in multiples of five minutes. This calls for special statistical techniques. Ignoring the phenomenon of rounding leads to biased estimation results for shorter distances. Rather surprisingly, the distance as the crow flies and the network distance appear to be slightly better proxies of the reported travel time compared with the shortest network travel time as indicated by the route planner. We conclude that where actual driving times are missing in commuting research the other three indicators mentioned may be used as proxies, but that the following problems may emerge: actual travel times may be considerably higher than network times generated by route planners, and the average speed of trips increases considerably with distance, implying an overestimate of travel time for long distance commuters. The only personal feature that contributes significantly to variations in reported travel times is gender: women appear to drive at lower average speeds according to our data. As indicated in the paper this may be explained by the differences in the car types of male and female drivers (females drive older and smaller cars) as well as higher numbers of stops/trip chaining among women. A concise analysis is carried out for carpoolers. Car-pooling leads to an increase in travel time of some 17% compared with solo drivers covering the same distance. In the case of car poolers, the above mentioned measures appear to be very poor proxies for the actual commuting times. Received: November 1996/Accepted: January 1998     

A qualifications trap in the German construction industry: changing the production model and the consequences for the training system in the German construction industry

German construction companies traditionally rely on qualified workers. This has influenced both their production model (work organization on site) and their policy towards training and education. Due to the massive inflow of workers from countries with low labour costs, firms may fundamentally change this model to a new one which is distinguished by the combination of less qualified workers with a larger number of managers for instruction, supervision and control. This change is initially likely to have a considerable knock-on effect on the training system. However, what is even worse is that the new model is not likely to work in the long run. To date the construction industry has acquired its site managers and supervisors directly from the pool of qualified workers. By reducing training it produces a shortage of the very resource inevitably needed to be able to reduce training. The industry will fall into a qualifications trap. What is more significant is that this trap is shown as a first step towards lowering corporate image, quality of human resources, productivity and, in the end, competitiveness.     

多年龄段老年人出访公园可达性影响因素和 空间评价研究——以武汉市中心城区80个公园为例

可达性是影响老年人出访公园的关键点之一,年龄 阶段、交通条件、公园数量与分布都会对老年人的实际可达性 距离产生影响。基于多源大数据,以武汉市中心城区范围内80 个公园和出行访问公园的11万人次老年人为研究对象,研究不 同年龄阶段的老年人出访公园的可达性距离和相关影响因素, 并据此展开空间评价。在可达性距离方面,数据统计显示,老 年人访问公园实际可达性距离约在6 km,“超标”情况普遍, 且在空间上以二环线为界,内外差异明显。在相关影响因素方 面,当公园可达性距离超过1.5 km时,随着距离的增加,年龄 越大的老人出访比例会越低;当公园与居住地的距离超过老年 人适宜的模式(步行2 km)时,老年人可能因不愿改变出行方式 而减少出行;当公园彼此布点距离在3 km以内时,随着布点密 度的增加,会一定程度上提升高龄老年人的出访意愿。在空间 评价方面,通过地理加权回归模型,发现汉阳西部、洪山中南 部居住的老年人出访公园出行比例异常偏低,三环线边缘的部 分公园较难吸引周边老年人出访。总体而言,一方面拓展了老 年人出访公园可达性的研究技术框架;另一方面能为相关规划 建设提供指引建议,实现理论与实践互促。     

Forecasting Freeway Link Travel Times with a Multilayer Feedforward Neural Network

One of the major requirements of advanced traveler information systems (ATISs) is a mechanism to estimate link travel times. This article examines the use of an artificial neural network (ANN) for predicting freeway link travel times for one through five time periods into the future. Actual freeway link travel times from Houston, Texas, that were collected as part of the automatic vehicle identification (AVI) system were used as a test bed. It was found that when predicting one or two time periods into the future, the ANN model that only considered previous travel times from the target link gave the best results. However, when predicting three to five time periods into the future, the ANN model that employed travel times from upstream and downstream links in addition to the target link gave superior results. The ANN model also gave the best overall results compared with existing link travel time forecasting techniques.     

A retrievable sensor installation technique for acquiring high frequency signals

The use of in-seam waves for void detection in mines requires the capability of capturing high frequency signals over large distances.For instance,the Airy phase of Love waves which are used for void detection in coal mines ranges from several hundred to over one thousand Hertz and the expected travel distance of these signals is at least 90 m(equivalent to a detection distance of 45 m) for the technique to be considered practical.In order to obtain high quality and broadband signals,sensors are conventionally grouted at the bottom of boreholes so that the attenuation due to the fractured surface is minimized and the coupling effect is improved.However,to be economically feasible,the expensive and high sensitive sensors must be retrievable so that they can be used repeatedly at the same or other locations.Because of these concerns,a retrievable sensor installation technique was developed.This paper provides a detailed review of the technique as well as a brief discussion of its applications.The technique is simple and reliable for both installation and retrieval operations and can be used for boreholes oriented in any directions.The technique has been demonstrated in over 200 sensor installation/retrieval operations under various borehole conditions,including bituminous coal,anthracite coal,shale,sandstone and trona.With this technique,we were able to detect the high frequency signals required for our projects.For instance,the signals used at a trona mine for void detection have a typical frequency of 5 kHz with the travel distance of 150-200 m.The results of these operations have shown that sensors installed in the prescribed manner exhibit predictable,consistent,and repeatable performance.The technique also provides an economical and reliable means for many other field seismic monitoring applications where high quality and broadband signals are essential,such as microseismic monitoring and geotomography studies.     

基于 AHP 与广义最短距离的 GIS 选址方法

GIS的空间分析功能使其应用于选址时有独到的优势,现普遍应用的GIS多准则决策分析选址模型多为层次分析模型,其得结果为非劣解集,且没考虑交通网络。而距离是很多设施空间选址时必须考虑的因素,本文将基于层次分析模型的GIS选址方法和传统选址方法中的步行距离最小模型结合起来,得到考虑多种因素和路网结构下的步行距离最小的选址结果,使选址更符合实际,且通过实例验证该方法的可行性。     

上海轨道交通无障碍环境建设的再思考

城市无障碍交通体系的建设已经成为现代城市一种发展趋势。改善行动不方便者的交通出行是城市的一项重要责任,同时又可以提高城市运行的效率。已经进入老年社会的上海,因老致残的比例日益提高。交通出行是人们的一项基本权利,我们必须及早采取有效应对措施,建设一个更加宜居的城市。上海轨道交通无障碍环境建设起步早,已成为残疾人出行的重要交通工具,但也还存在一些不便之处。首先阐述了上海轨道交通无障碍环境建设的背景,分析存在的问题,指出在轨道交通无障碍环境建设中理念转变的重要性。通过对国际无障碍建设先进理念的分析,结合上海的实际情况,提出上海轨道交通无障碍建设的建议。     

一种气动履带式钻车行走机构的改进设计

气动履带式钻车是一种工程用凿岩钻孔设备。其行走机构设计是否合理,直接影响到其钻孔效率,乃至整个工程进度。行走速度太快,钻车在复杂的施工现场行走产生剧烈的震动,会严重损害钻臂,乃至整车的所有部件,钻孔时也不易对准所钻的孔位;行走速度太慢,钻孔移位慢,钻孔后撤离爆破现场的动作也慢,影响整个工程的进度。钻车要有一合理的行走速度、足够的牵引力和爬坡能力。就某型气动履带式钻车的结构特点,通过分析论证介绍了一种合理的改进设计该气动履带式钻车行走机构的方法。