Developing a production management modelling approach for precast concrete building products

Production management in this research is concerned with three key decisions: demand forecast, production scheduling and stock forecast. These three decisions are very much interrelated and cannot be made in isolation. Previous studies of precast concrete industry activities concluded that production management is fragmented. For example, production planning is done in isolation from demand forecasting and from stock forecasting. This has contributed to poor production management performance in terms of resource utilization and over-stocking. This paper goes beyond traditional production management theories and practices and develops a model to integrate all aspects of production management. The main objective is to develop an integrated production management model for the make-to-stock sector of precast concrete building products, in order to help production managers make better planning decisions and explore alternative options. The model is a factory simulator which examines and evaluates the effect of several managerial strategies on production planning and stock forecasting before actual production commences. It uses different measures of performance which facilitate the choice of planning strategies under various demands and factory conditions.     

Stockyard layout planning in precast concrete products industry: a case study and proposed framework

Management of the stockyard layout in the precast concrete products industry is very important for efficient storage and dispatch of the concrete products. The industry uses the make-to-stock principle in production to meet the seasonal demand (high in summer and low in winter) from the construction industry. In order to stabilize production output and cater for the huge demand in summer, stock is built up during the winter and spring period. The concrete products are kept in stock for 4–5 months. As 2000≈3000 different precast concrete products are produced, and the products have different size, weight and handling requirements, determination of appropriate stockyard location for the products constitutes a complex process. This paper describes some ongoing research that is focused on identifying the appropriate methodology for designing and managing the stockyard layout that ensures efficient storage and dispatch of products, and provides ease of rotation of products within the yard. An integrated simulation model employing artificial intelligence methods has been proposed to evaluate ‘what-if’ scenarios and recommend a suitable methodology for the management of stockyard space for precast concrete products. This paper presents the findings from a case study, which includes work-study, frequency analysis of historical order data. The paper also introduces the specifications, processes and outline prototype of the proposed model. A general purpose simulation language (SIMAN) based software, ‘Arena 4.0’ (Systems Modelling Corporation), has been selected to develop the prototype simulation model and ILOG views and rules have been considered to generate a knowledge-based stockyard layout.     

Diffusion of ISO 9000 certification in the precast concrete industry

ISO 9000 is one of the most important administrative innovations of the last two decades. The Turkish precast concrete industry is an interesting example of the diffusion of this important administrative innovation. Innovation diffusion theory proposes that the diffusion of an innovation is driven by internal (i.e. behaviours of copying others) and external (i.e. complying with client requirements, changes in government regulations, demand conditions, and consulting firms' suggestions) influence factors. The propositions of innovation diffusion theory are empirically tested by using three mathematical models: the internal influence model, the external influence model and the mixed influence model. The mixed influence model has the highest explanatory power and the diffusion of ISO 9000 certification in the precast concrete industry is primarily driven by internal rather than external influence factors.     

对现阶段我国预制混凝土桩行业发展的几点思考

结合多年从业经验,阐述了现阶段我国预制混凝土桩产品种类、生产企业分布、技术装备和应用情况,分析了我国预制混凝土桩行业目前存在的主要问题,如机械化水平不高、工业化和信息化融合水平较低、产品多样性不足、安全生产及绿色环保理念落后、产品应用领域较窄等,并结合我国政策要求、技术水平、行业发展对预制混凝土桩行业的可持续发展进行了展望,为预制混凝土桩行业的可持续发展提供借鉴。     

Developing Crew Allocation System for the Precast Industry Using Genetic Algorithms

Abstract: The Precast Concrete Industry (PCI) is one of the major contributors to the national economy and can be categorized as labor‐intensive industry. It is currently experiencing shortcomings in terms of delivery products at a competitive cost and time. This is mainly due to the inefficiencies associate with planning and scheduling of skilled operators within crew configurations. This article presents a new strategy for efficient allocation of crews of workers in the precast concrete industry using Genetic Algorithms‐based simulation modeling. The aim of this study is to develop a crew allocation system that can efficiently allocate possible crews of workers to precast concrete labor‐intensive repetitive processes. Genetic algorithms (GAs) have been developed to solve this type of problem. Process mapping methodologies were used to identify and document the processes involved in producing precast components. Then process simulation was used to model and simulate all these processes and GAs were tailored to be embedded with the simulation model for a better search of promising solutions. GA operators were designed to suit this type of allocation problem. “Class Interval” selection strategy was developed to give a greater opportunity for the promising chromosomes to be chosen for further investigation. Dynamic crossover and mutation operators were developed to add more randomness to the search mechanism. The results showed that adopting different combinations of crews of workers had a substantial impact on reducing the process throughput time, minimizing resources cost, and achieving the required operatives utilization.     

Intelligence approach to production planning system for bespoke precast concrete products

Bespoke precast concrete products are widely used components of construction projects. These products implement the offsite prefabrication technology that offers a unique opportunity for innovation and cost savings for construction projects. However, the production process from design to manufacturing contains uncertainties due to external factors: multi-disciplinary design, progress on construction site. The typical workload on bespoke precast factories is a complex combination of uniquely and identically designed products, which have various delivery dates and requirement of costly purpose-built moulds. In this context, this research is aimed to improve the efficiency of the process by addressing the production planning because it has a significant impact to the success of the production programme. An innovative planning system and its prototype called ‘Artificial Intelligence Planner’ (AIP) are developed. AIP is capable of two functionalities. The first is a data integration system that encourages the automation in the planning process. The other is a decision support system for planners to improve the efficiency of the production plans. These functionalities reinforce each other to deliver optimum benefits to precast manufacturers. AIP have employed artificial intelligence technologies: neural network and genetic algorithm to enhance data analyses for being a decision support for production planning. The outcomes of the research include shortened customer lead-time, in-house repository of production knowledge, and achievement of the optimum factory's resource utilisation.     

Long range planning of prefabrication industry in a national economy (summary)

The objective of long range planning of the precast industry in a national economy is to determine the optimal location and capacity of prefabrication plants in the various stages of the planning horizon. The planning process described here consisted of several steps. First, the demand for precast elements in the planning horizon and its geographical dispersion were established. Then the cost of operation of new plants of various capacities was estimated. Later, a survey of existing plants was performed and their cost at present and increased production capacity levels was evaluated. The transportation cost of precast elements between existing and prospective plant locations and the various demand areas were estimated. Finally, the optimal location and capacity of required plants—both existing and new—were determined for the various stages of the planning horizon, with the aid of a mathematical model. The sensitivity of the solution to constraints imposed on the operation and capacity of various existing plants was also examined.     

浅议新营业税的实施对建筑业的影响

《新营业税暂行条例及实施细则》实施后,有关建筑业的规定有所调整,文章分析了新营业税暂行条例涉及建筑业的几大主要变化,包括扣缴义务人的变化、纳税地点和纳税义务时间等方面的调整,并结合新条例中建筑业营业税政策的变化,重点阐述了新营业税暂行条例扣缴义务人的变化对企业的影响。     

化蛹成蝶 洛建再踏征程

2010年1-11月,洛建销售收入同比增长87%,利润同比增长487%。公司压路机销量突破2000台,销售收入4.5亿元。压路机销量增幅75%,其中大型压路机同比增长89%,增幅位居行业第一。     

延展型销售漏斗管理

销售漏斗（也叫销售管线）是科学反映机会状态以及销售效率的一个重要销售管理模型。通过对销售管线要素的定义（如：阶段划分、阶段升迁标志、阶段升迂率、平均阶段耗时及阶段任务等），形成销售管线管理模型。通过对销售漏斗的管理可以及时发现销售机会，准确评估销售人员和销售团队的销售能力，发现销售过程的障碍和瓶颈。     

Process reengineering and improvement for building precast production

Current production methods for the building of precast concrete elements are gradually becoming insufficient to meet industry demands. Most precast factories incorporate fixed molding production lines to produce building structural elements such as beams, trabeculae and pillars. Improvement of current production has reached its limits. The objective of this study is to perform process reengineering so as to create more efficient precast processes. The results of the literature review and advice from 16 experts suggest that the current process used to produce a precast element, which is comprised of 16 steps in a single module, should be redesigned to include 13 steps in 3 modules. Using historical data as input, the Arena software, Version 13, is adopted to simulate both the traditional and proposed methods, and then compare the results for practicability. An overall savings of production time of 24% can be reached by changing the current/traditional method to the flow-shop type production method.     

Estimating a project's profitability: A longitudinal approach

Forecasting a project's financial performance is central to aligning its operations with its strategic direction. Despite the panoply of approaches to predicting project performance, most studies focus on predicting the working capital and fixed capital requirements of projects. Few focus on forecasting profitability in the capital project industry. Thus, this longitudinal study of 121 capital projects identifies key variables in project initiation and planning phases that affect the profitability (return on sales) of completed projects. Subsequent multivariate robust regression analysis shows that the natural logarithm-transformed Scope and Team variables best explain the variation in profitability. The results show that the mean absolute percentage error (MAPE) value in the optimal forecasting model is 17.91%. Ultimately, our findings suggest that it is feasible to estimate a project's profitability before its execution.     

混凝土机械市场井喷 国产化配套需加力

2010年,中国工程机械行业实现了井喷式的高速增长。作为其子行业之一,混凝土机械尤其突出。近日,针对2010年中国混凝土机械市场情况和未来发展趋势,本刊特别采访了中国工程机械工业协会混凝土机械分会盛春芳秘书长。     

取消预制空心板的利弊分析

我国预制空心板曾作为建筑楼、屋盖的主导产品得以广泛应用 ,随着预拌混凝土现浇技术的飞速发展 ,预制空心板正逐步走向消亡。本文就取消预制空心板所带来的利弊进行分析 ,提出对预制空心板重要的不是简单取消 ,而是如何创新、发展     

Construction related factors influencing the choice of concrete floor systems

Designers have a wide choice of concrete floor systems for their buildings. They can choose from three basic types available: in situ, precast or hybrid construction. A survey was conducted within the UK construction industry to investigate, in particular, the construction related factors influencing the choice of concrete floor systems. The data collected were subjected to frequency and severity index analyses, Kendall's concordance test and the chi-squared tests to produce a rank ordering of 12 construction related factors. Five factors were identified as being the most important, namely ‘appropriateness of use’, ‘cost’, ‘constructability’, ‘speed’ and ‘health and safety’. These five factors reflect current industry emphasis, and therefore could be adopted as the principal criteria for evaluating and selecting concrete floor systems during the design stage. They could also be used as assessment criteria for developing future systems.     

我国工程机械产品出口状况及面临的挑战

1工程机械行业出口概况1.1工程机械行业"十一五"期间运行主要指标(见表1)1.22010年行业运行主要经济指标据协会统计:全国工程机械行业主要企业主要产品销售收入同比增长52.27%;主要产品销量同比增长61.63%(见表2)。1.32011年12月主要经济指标据协会统计:2011年1~2月全国工程机械行业主要企业主     

预制混凝土小型空心砌块施工实践

随着建筑节能墙体的推广 ,预制混凝土小型空心砌块在承重墙体中得到了广泛应用。就此阐述了小型空心砌块的施工要点、质量控制措施、成品保护等 ,提出小型空心砌块对节能与节土有重要意义     

预制钢筋混凝土剪力墙结构抗震性能研究综述

为加快建筑工业化进程,预制钢筋混凝土剪力墙结构近年来成为研究重点。对预制混凝土剪力墙结构抗震性能相关内容进行了回顾总结:1)预制剪力墙结构震害情况;2)国内外预制钢筋混凝土大板结构、无粘结后张拉预应力预制混凝土剪力墙结构、预制叠合剪力墙结构研究成果;3)预制钢筋混凝土剪力墙结构的水平接缝、竖向接缝、钢筋连接方式等研究进展。并对预制剪力墙结构国内抗震设计规范进行了简要介绍,就装配式剪力墙结构今后研究重点与待解决问题给出了建议。     

Developing a precast production management system using RFID technology

Radio Frequency Identification (RFID) is characterized with superior predispositions, including the recognition of multiple markers, communication ranges from five to six meters, and a storage database for thousands of data files. These unique features resolve data storage and record-reviewing difficulties, prevent repetitive data entries, and facilitate instant feedbacks.The precast industry is a management-intensive sector, for which pivotal issues include methods relevant to the instant provision of acquired management information to executive managers, materials of precast concrete products, quality control inspection and inventory and transportation management information, and convenient data entry for frontline personnel.It is anticipated to integrate usage of Personal Digital Assistants (PDA) and the application of Radio Frequency Identification (RFID). Using RFID tag and reader to collect the information, and then transmit the multi-faceted, mobilized information such as the production quantity, the materials quantity, quality control inspection and inventory and transportation management information to the manager office or the site worker via the PDA and wireless Internet.This precast production management system which has been developed by the author and utilized in precast production management encompasses inspection of incoming materials, production process inspection, molds inspection, specimen strength feedback, and logistic and receiving management. The mobilized information frame elaborated in this proposal can, to certain degree, be regarded as a reference for the construction of a mobilized precast industry management system.     

纵筋浆锚连接预制柱的抗震性能试验研究

将预制混凝土柱外伸纵向钢筋插入预先埋设在基础中,灌有高强浇筑料的波纹套管内,可实现预制混凝土柱与基础的连接。为研究采用该方法连接的预制 柱的抗震性能,进行了8个预制混凝土柱和1个用于对比的普通整体现浇柱,在低周往复荷载作用下的抗震性能试验。试验考虑了3个方面的影响因素：①轴 压比的影响;②柱箍筋强度等级的影响;③柱脚5倍纵筋直径范围内,钢筋与混凝土黏结状况的影响。试验结果表明：①采用本文方式连接的预制柱,其能 量耗散系数与整体浇筑柱的能量耗散系数相当,但预制柱的延性系数均大于整体浇筑柱的延性系数;②将柱脚5倍直径范围内钢筋与混凝土进行无黏结处理 后,柱的延性系数可增大18%~25%,能量耗散能力可提高13%~20%;③提高柱箍筋的强度等级可提高柱的延性系数5%~10%,提高柱的能量耗散能力8%~16%。