1,721,140 research outputs found
EDITORIAL CONSTRUCTION MANAGEMENT WORKSHOP 2018
No full textThis workshop on Construction Management (CMW18) follows the preceding edition in 2013, again in Ravenna, concerning new research themes and fields of innovation for construction management. The workshop of 2018 focuses on possible and future implementation of digital technologies in the building sector, generally addressed as industry 4.0. This is to be addressed without forgetting other important drivers of change in the societies, business environments and in the real estate and construction sector (REC) itself. The environmental concerns and climate change are already now sources for large scale regulatory changes. On the long run the overall performance of the REC sector shall play a major role in tackling the environmental challenges. This will be also construction and real estate management challenge. The performance of the sector can be improved only via large scale systemic changes and innovation
A proposal for a new mechanism of interaction of trialkyltin (TAT) compounds with mitochondria
No full textThe interactions of trialkyltin (TAT) compounds with the mitochondria were largely studied The current view of this phenomenon is that these compounds, by exploiting the Cl- and OH- gradient in energised mitochondria, behave as electroneutral OH-/Cl- exchangers. Experiments performed with triethyltin-, tripropyltin-, and tributyltin-chloride, allow as to propose an alternative mechanism. The crucial point of this new mechanism is that TATs enter the mitochondria as lipophilic cations (alkyl)(3)Sn+ and not as electroneutral compounds. The influx is followed by extrusion of the trialkyltin compounds as electroneutral hydroxi compounds (alkyl)(3)Sn-OH. Measurements of membrane potential show that the uptake of the TAT cation (alkyl)(3)Sn+ is followed by membrane depolarisation measured as the release of the trimethylphenylphosphonium probe. The depolarization occurs in the order: (Et)(3)Sn-Cl < (Pro)(3)Sn-Cl < (Bu)(3)Sn-Cl in agreement with the increasing lipophilicity of the tested compounds from ethyltin toward butyltin derivative. The uptake of TAT induces the opening of a selective anionic channel which could explain the swelling of mitochondria observed in a chloride mediu
Using Genetic Algorithms for optimizing and modelling Time, Cost and Quality trade offs of construction projects
No full textThe well-known “iron triangle” and its attributes, time, cost and quality has still importance as a framework of basic objectives of construction projects. In practice, construction project managers can optimise time and costs with the well-known time/cost trade-off approach, but quality optimization versus cost and time performances in construction project is usually pursued in a rather intuitive manner based upon Project Manager’s experience. The research behind this paper is proposing a specific approach where three possible estimates for time, cost and quality form starting points for the optimisation of project performance. The estimates are based on characteristic of alternative technical solutions such as possible commercial products to be used or assembled. The effectiveness of various combinations is evaluated with an optimisation procedure based upon Genetic Algorithms. A simple pilot study of a renovation project of two residential apartment is presented to test the proposed approach. The gained results are demonstrating the possibilities of genetic algorithms for such trade off analyse
Demolire o Riqualificare? LCA e Analisi Multi-Criteria per il caso della ricostruzione post-sisma / Demolish or Redevelop? LCA and Multi-Criteria Analysis for the case of post-earthquake reconstruction
No full textThe debate on demolition and reconstruction, as an alternative to the building redevelopment of existing residential buildings, certainly has been an issue of capital importance for operators and researchers of residential construction sector for several decades, at a national and international level. It is a question, indeed, of evaluating whether the demolition process and consequent reconstruction of an existing building with better technological performances from an energy and seismic point of view, is more environmentally sustainable than the deep renovation process. The scientific evidence in favor of one or the other approach is still object of debate and actually is uncertain. Actually, building sustainability is a critical point in this evaluation and Life Cycle Assessment - LCA is the most important approach to assess building sustainability. Nevertheless, some other sustainability – related indicators can be defined, therefore a Multi-Criteria approach is needed. The case study of a deep renovation of an existing residential building damaged by the earthquake of Emilia Romagna of 2012 is addressed. By simulating the demolition and re-construction project and comparing it with the actual deep renovation project, the LCA approach is used to evalute the most sustainable building strategy. Analitic Hierachic Process is used as a multi – criteria analysis to take into account other important sustainability indicators
Toxic effects of new antifouling substances on tunicate haemocytes. I. Sea-nine and chlorothalonil.
No full textAfter the definitive ban on tin-based antifouling substances, new organic compounds have recently been introduced in antifouling paint formulations, as either principal or booster biocides. In most cases, previous risk assessment of these biocides has been inadequate so that their possible effects on aquatic ecosystems is a matter of great concern.We studied the effects of two neworganic biocides often associated in paint formulations, Sea-Nine 211TM (4,5 dichloro-2-n-octyl-4-isothiazoline-3-one) and chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile), on haemocytes of the compound ascidian Botryllus schlosseri exposed for 60 min to various concentrations (from 0.1 to 10 μM) of the xenobiotics. This species had previously proved to be a good bioindicator of organotin compounds. Both compounds, at concentrations of 1 and 10 _M, altered the morphology of phagocytes, and these changes were closely related to disrupting effects on cytoskeletal components. At the same concentrations, phagocytosis, which requires cytoskeletal modifications for pseudopod formation, was severely hindered. Both compounds were able to induce apoptosis of Botryllus blood cells, probably as a consequence of severe oxidative stress related to the reported decrease of intracellular reduced glutathione (GSH) content. In the case of Sea-Nine 211TM, a substantial increase in intracellular Ca2+ and a negative effect on Ca2+–ATPase activity may also be involved in the activation of the cell death machinery. Cytochrome-c-oxidase was also significantly inhibited by the two biocides, indicating perturbation of the mitochondrial respiratory chain. Isodynamic mixtures of Sea-Nine 211TM and chlorothalonil were used to evaluate the occurrence of interactions between the two compounds. Results suggest the combined action of partial additivity when cell-spreading and cytochrome-c-oxidase activity were considered, and were indicative of antagonism in the case of the GSH depletion. On the whole, our results indicate that short-term in vitro exposure of haemocytes to high concentrations of Sea-Nine 211TM and chlorothalonil provokes a marked reduction in haemocyte functionality, higher than or comparable to that of TBT. These assays of acute toxicity stress the immunosuppressive potential of these compounds, which, although counterbalanced by their short half-life in the marine environment, can lead to biocoenosis dismantling through rapid bioaccumulation by filter-feeding non-target benthic organisms
Quality Driven Scheduling in Construction
Full text linkDespite the enormous research effort that has been made in the last fifty years, the goal of construction scheduling quality seems still a long way far. This dissertation has the aim of contributing to the understanding of the quality of construction scheduling, and three issues have been chosen: schedule quality; quality and project control; scheduling approaches for construction. The goal of the whole research work is to study quality in scheduling and project controlling, and to propose some possible research lines to better understand the needed quality for the planning, scheduling, and controlling approaches in construction projects, i.e. quality driven scheduling.Starting from the development of the Critical Path Method (CPM), PERT and Precedence Diagramming, until the recent Location-Based Planning, project scheduling has been developing and improving continuously. However, construction project scheduling systems are still considered to miss the goal of increasing project control efficiency. Project Scheduling is, indeed, one of the basic tools of construction project management, and the success of a project partially depends on having a high quality schedule that defines when each activity will occur and with which duration, and its logic links with other activities and their sequences. Moreover, construction productivity is considered to be improved through scheduling as it can manage different problems such as process productivity, coordination and safety, and connections between systems and processes. Quality of construction scheduling has been object of research in a rather limited manner, and the need of recommended schedule development practices for quality assurance of scheduling processes and deliverables still exists. Therefore, the research work is based upon three main research questions: a) what is schedule quality? b) what does scheduling produce in terms of quality? c) can the activity network schedule model be process-oriented and quality driven? The gained results propose the following regarding to the research questions.a) What is schedule quality? Schedule quality is the fulfilment of many schedule requirements, with the aim of satisfying the needs of work structuring of construction process and of scheduling mechanics. A method of understanding and measuring schedule quality in construction, termed “Schedule Health Assessment” is proposed. The Schedule Health Assessment method also has the aim of guiding the project scheduler in the schedule development process.b) What does scheduling produce in terms of quality? Project schedule is the basis for project control, mostly addressing time and progress of activities, and costs, while quality control is usually separated. Although, these three project objectives are interdependent, and process and product quality management should be fully included in project control. Quality control should be integrated in the project schedule through a “Quality Breakdown Structure”.c) Can the activity network schedule model be process-oriented and quality driven? Activity network creates logic of work structuring. A process-oriented scheduling method for construction has to deal with resources, workflow and spaces. The proposed method, termed Repetitive Networking Technique (REPNET), creates a quality driven construction-oriented schedule model by plotting network logic on resource-space charts and on flowlines.The research results suggest the implementation of these three approaches in the project scheduling of a construction project can improve the quality driven scheduling of the project, meaning the implementation of a good quality schedule, the integration in project control processes of the delivered quality and the process-oriented scheduling
Multi-objective Genetic Algorithm for the Time, Cost, and Quality Trade-Off Analysis in Construction Projects
No full textProject management methods and practice address project success, and the well-known “iron triangle” targeting time, cost and quality trade-off has a great importance in this process. Quality optimization, including safety and sustainability, plays a key role in construction project management choices. Since the relationship between quality, time and cost can be different from case to case, an application of artificial intelligence (AI) has been proposed for this purpose. The objective of the research work under this paper is to demonstrate that AI applications can help project managers the trade-off between time, cost and quality objectives. A comprehensive approach concerning three estimates of time, cost and quality of project activities is proposed to optimize project performance in construction. The proposed approach implements a genetic algorithm to optimize project performances, with the aim of creating a decision support system for construction project managers. Genetic Algorithm is an AI application that creates a learning optimization process that discard worse solutions and re-introduce better solutions to search for an optimal or sub-optimal solution. Therefore, time, cost and quality trade-off can be performed by a Multi-Objective Genetic Algorithm that evaluates the effectiveness of various combinations, selecting better solutions with an iterative process. Therefore, the most suitable balancing between three project targets can be achieved. A simple case study of a deep renovation project of two residential is presented to evaluate the proposed approach with a sample application. This study contributes to the understanding of AI applications for construction management
The interactions of trialkyltin compounds with lysosomes from rat liver
No full textInteractions of two trialkyltin compounds with the lysosomes from a rat liver have been studied. It is shown that these compounds induce a fast alkalinisation in the matrix of energised lysosomes. The fast alkalinisation rate is similar to the one obtained with uncouplers of the oxidative phosphorylation. An identical effect has been obtained with lysosomes energised in a chloride Free medium. This supports the hypothesis that trialkyltin compounds behave not only as Cl- /OH- exchangers, but also as proton carriers in biological membranes. This result could explain the toxicity and in particular the neurotoxicity of trialkyltin compound
Bioavailability of Toxic Elements in the Sediments of Guanabara-Bay (Rio de Janeiro/Brazil)
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