CME Forum: a response to “Construction flow index: a metric of production flow quality in construction”

The study of types of flow in construction is a relatively new field. This paper reviews the work of Sacks et al. and reveals that they have applied a production-line metaphor with recognition of two production flows. Process flow: locations are equated with products moving down a production line. Operations flow: work crews are equated to work stations. Their work proposes an index of the quality of production flow in construction, but the research design has three significant flaws: the skilled interpretation of flow-line charts is not in turn applied to the interpretation of their example charts; the conceptual framework does recognize that the underlying metaphor requires levels of detail in both location and task that is not supported in their analysis. The meaning of “quality of flow” in this context is not defined. This debate raises important epistemological questions for those working in lean construction and location-based management. While the concept of “production flow quality” is important, the Sacks et al. methodology does not address the detailed planning of individual crews. It is only possible to apply the production-line metaphor if micro-management is adopted as detailed planning.     

BIM-to-IGA: A fully automatic design-through-analysis workflow for segmented tunnel linings

Both planning and design phase of large infrastructural project require analysis, modelling, visualization, and numerical analysis. To perform these tasks, different tools such as Building Information Modelling (BIM) and numerical analysis software are commonly employed. However, in current tunnel engineering practice, there are no systematic solutions for the exchange between design and analysis models, and these tasks usually involve manual and error-prone model generation, setup and update. In this paper, focussing on tunnelling engineering, we demonstrate a systematic and versatile approach to efficiently generate a tunnel design and analyse the lining in different practical scenarios. To this end, a BIM-based approach is developed, which connects a user-friendly industry-standard BIM software with effective simulation tools for high-performance computing. A fully automatized design-through-analysis workflow solution for segmented tunnel lining is developed based on a fully parametric design model and an isogeometric analysis software, connected through an interface implemented with a Revit plugin. The IGA-Revit interface implements a reconstruction algorithm based on sweeping teachnique to construct trivariate NURBS lining segment geometry, which avoids the burden to deal with trimmed geometries.     

Bayesian network construction from event log for lateness analysis in port logistics

The handling of containers in port logistics consists of several activities, such as discharging, loading, gate-in and gate-out, among others. These activities are carried out using various equipment including quay cranes, yard cranes, trucks, and other related machinery. The high inter-dependency among activities and equipment on various factors often puts successive activities off schedule in real-time, leading to undesirable activity down time and the delay of activities. A late container process, in other words, can negatively affect the scheduling of the following ones. The purpose of the study is to analyze the lateness probability using a Bayesian network by considering various factors in container handling. We propose a method to generate a Bayesian network from a process model which can be discovered from event logs in port information systems. In the network, we can infer the activities’ lateness probabilities and, sequentially, provide to port managers recommendations for improving existing activities.     

Formal Approach to Workflow Application Fragmentations Over Cloud Deployment Models

Workflow management technologies have been dramatically improving their deployment architectures and systems along with the evolution and proliferation of cloud distributed computing environments. Especially, such cloud computing environments ought to be providing a suitable distributed computing paradigm to deploy very large-scale workflow processes and applications with scalable on-demand services. In this paper, we focus on the distribution paradigm and its deployment formalism for such very large-scale workflow applications being deployed and enacted across the multiple and heterogeneous cloud computing environments. We propose a formal approach to vertically as well as horizontally fragment very large-scale workflow processes and their applications and to deploy the workflow process and application fragments over three types of cloud deployment models and architectures. To concretize the formal approach, we firstly devise a series of operational situations fragmenting into cloud workflow process and application components and deploying onto three different types of cloud deployment models and architectures. These concrete approaches are called the deployment-driven fragmentation mechanism to be applied to such very large-scale workflow process and applications as an implementing component for cloud workflow management systems. Finally, we strongly believe that our approach with the fragmentation formalisms becomes a theoretical basis of designing and implementing very large-scale and maximally distributed workflow processes and applications to be deployed on cloud deployment models and architectural computing environments as well.     

Exploration and design of knitted composites for architectural application: The MeiTing project

Knitted composites are textile composite materials that consist of knitted textile reinforcement and polymer matrix. Knitted composites exhibit great design flexibility by allowing the customization of shapes, textures, and material properties. These features facilitate the optimization of buildings’ material systems and the creation of buildings with light weight and high material efficiency.To achieve such a lightweight, material-efficient building structure with knitted composites, this research investigates the material properties of knitted composites and proposes a design process for building-scale knitted composite systems. In the material study, this research examines certain mechanical properties of the material and the effects of additional design elements. In the design exploration, this research explores the design workflow of the structural form, element arrangement, and knit distribution of the material system at the macro-, meso-, and microscales. The project of MeiTing serves as proof of the concept and the design workflow.     

工作流自动化机制在数字医院系统中的应用

为了推进医院的数字化进程,实现医院诊疗流程的数字化,对当今医院的信息化现状进行了分析,充分利用J2EE体系架构的优势,结合医院诊疗流程的实际情况,详细分析、设计了适合医院诊疗流程的工作流管理系统．引入工作流自动化机制,可以降低原有医院部门科室之间固定的耦合关系,整合各个业务系统的功能模块,构建数字医院系统,实现医院诊疗流程的动态定制和快速二次开发,使医院的诊疗流程规范化、科学化和系统化．     

基于XGBoost与Stacking模型融合的短期母线负荷预测

母线负荷预测对于电网安全稳定调度具有重要意义,但母线负荷随机波动性较强,其负荷类型因供电区域的差异而不同。为此,提出一种基于极限梯度提升(XGBoost)与Stacking模型融合的短期母线负荷预测方法。基于XGBoost建立多个母线负荷预测元模型,组合构成Stacking模型融合的元模型层,连接一个XGBoost模型对元模型进行融合,整体构成综合预测系统,并采用粒子群优化算法优化系统参数。通过对具有不同负荷属性的220 kV母线进行实例分析,验证了所提方法的有效性与适用性。     

Challenges and opportunities for productivity improvement studies in linear,repetitive, and location-based scheduling

Despite theoretical advancements in alternative project planning methods the extent of their practical implementation varies strongly; it has been limited especially in the US construction industry. The family of linear, repetitive, and location-based scheduling techniques holds significant but barely substantiated promise by containing multiple variables of interest for integrated analysis and optimization. Yet it is necessary to provide empirical evidence that using such techniques can improve productivity to increase credibility and acceptance by practitioners, because claims of conceptual superiority are only sporadically supported with detailed measures. An analysis is performed to identify relevant decision-making variables, extract challenges that currently limit the corpus of quantitative productivity studies on alternative scheduling to its insufficient size, and reveal opportunities to expand it in breadth and depth. Variables are categorized by their relevance to time, activity, resource and location, as well as the managerial approach. Challenges include the diverse definitions of productivity itself, issues related to achieving generalizability, and the detailed steps of data collection, preparation, and analysis. Opportunities include the guidance from existing but rare studies and well-established research methods such as case studies that can be applied. This is illustrated with a sample project of a high-rise apartment building in Brazil. If alternative methods can be proven to be measurably better for specific applications, there might be a paradigm shift from merely defaulting to traditional but problematic network-based scheduling toward consciously choosing the planning method based on its potential benefits for a project.     

互斥约束工作流可满足性决策的匹配剪枝模式回溯法

针对用于工作流可满足决策的模式回溯技术如何平衡性能与代价的问题,提出了一种对部分模式解及时进行授权匹配验证的优化方法,牺牲一定验证效率以增强剪枝能力。就仅受互斥约束的问题情形,利用实例难易程度的两极分化现象对总体时间性能进行了分析。随机生成数据集上的实验表明,这一优化极大地降低了模式回溯在难实例上的时间代价,而对易实例执行时间的影响很小,且相对于其他基于动态规划的代表性算法,优化后的算法在时间和空间性能上均有显著优势。     

纸盒加工数字化流程的发展前景

随着数字化技术在包装印刷业的不断渗入,纸盒加工过程数字化的实现将倍受瞩目.文中从包装结构计算机辅助设计(CAD)技术、纸盒样品CAM系统、JDF技术等方面全面分析了纸盒加工数字化流程,阐述了纸盒加工数字化流程的发展前景.