CONCRETE PAVING PRODUCTIVITY IMPROVEMENT USING A MULTI-TASK AUTONOMOUS ROBOT
ABSTRACT To improve productivity in conventional concrete construction, autonomous robots that perform specific tasks are being developed. Single-task robots are capable of enhancing specific functions, though their impact on the overall productivity remains unclear. A robot that incorporates each task-specific piece of machinery used in the concrete paving process into one fully autonomous unit is evaluated. Assessing potential productivity from the use of a fully automated process is a required step for developing a full scale-system. With the purpose of identifying productivity benefits in an automated concrete paving operation, two concrete paving processes will be compared using simulation tools. One process is the conventional operation using intensive labour, slip form paving machine and auxiliary equipment. The other process is the automated operation using a fully autonomous robot. Applications of this assessment methodology based in simulation will allow for the determination of productivity indicators of automated operations in hazardous environments, using the respective results to complement prototypical tests.
Grand Challenges in Construction Management
This article is written for the launch of the specialty section on construction management at the Frontiers in Built Environment. This new specialty section opens an on-line platform for academics and practitioners in the subject field to share valuable experiences and findings from innovative research and development as well as practices, which focus on the management of people/workforce, product/production, and processes across built environment project stages, including development and construction, operation and maintenance, as well as demolition and redevelopment, under considerations on the dependability and productivity of construction management services. In this article, the writer presents his humble opinions limited from experiences from academic research and professional services around the world in the past three decades. The topics derived on grand challenges in construction management are gigantic in terms of their coverages, but may have huge impacts on professional development in both short and longer term. Discussions presented here on grand challenges in construction management consist of four parts to respectively focus on an initial cognitive framework of the construction management body of knowledge (CMBOK), intelligence pervasive construction management systems, interdisciplinary digital innovation, and solutions for performance enhancement in megaproject delivery. The research methodology that support the writer to describe the four grand challenges includes literature review, comparison study, site observation, and system architecture analysis and development. It was the writer’s initial abductive reasoning to identify the four grand challenges in construction management through an extensive literature review, which was based on national and regional strategies for the construction industry from the world top economies. Some key references relating to these four major topics are collected to support discussions in this article. It is expected that this article could contribute to the debate as well as research and development in construction management in terms of continuous technical enhancements on project-oriented performance and value regardless the scope, the location and the time associated and concerned. As the study was conducted through abductive reasoning, this article should have its limitation on the coverage to all grand challenges in construction management, and this should leave many unanswered questions for further exploratory research.
Improving Hollow Fiber Dialyzer Efficiency with a Recirculating Dialysate System II: Comparison Against Two-Chamber Dialysis Systems
The theoretical basis of the nonregenerated recirculating dialysate system (RDS) was derived in Part I of this work [M. Prado, L. M. Roa, A. Palma, and J. A. Milán, Ann. Biomed. Eng. (2005)]. This system pursues the maximization of the clearance of hollow fiber dialyzers whose performance is controlled by diffusion, as occurred in standard hemodialysis. In this second part we perform a comparison by digital simulation of the RDS against three well-known two-chamber dialysis systems. As a major outcome, the efficiency of the RDS increased by a factor of five–eight with respect to the efficiency of a single dialyzer operating with a number of transfer units equal to 0.1, that is when the diffusive mass-transfer of the dialyzer is exhausted. Present low-flux dialyzers do not take advantage of the full potential of this technique, but the functional domain where high-flux and high-area dialyzers operate could be more suitable to exploit this technique. We conclude that RDS can be a competitive efficient technique for optimizing the dialysis efficiency.