Economic and Environmental Evaluation and Optimal Ratio of Natural and Recycled Aggregate Production

Steady increase in overexploitation of stone quarries, generation of construction and demolition waste, and costs of preparing extra landfill space have become environmental and waste management challenges in metropolises. In this paper, aggregate production is studied in two scenarios: scenario 1 representing the production of natural aggregates (NA) and scenario 2 representing the production of recycled aggregates (RA). This study consists of two parts. In the first part, the objective is the environmental assessment (energy consumption and CO2 emission) and economic (cost) evaluation of these two scenarios, which is pursued by life-cycle assessment (LCA) method. In the second part, the results of the first part are used to estimate the optimal combination of production of NA and RA and thereby find an optimal solution (scenario) for a more eco-friendly aggregate production. The defined formulas and relationship are used to develop a model. The results of model validation show that the optimal ratio, in optimal scenario, is 50%. The results show that, compared to scenario 1, optimal scenario improves the energy consumption, CO2 emissions, and production cost by, respectively, 30%, 36%, and 31%, which demonstrate the effectiveness of this optimization

A Development Model for Identifying the Uncertainty Sources and Their Impacts on Bridge Construction Projects

Bridge construction projects are rife with uncertainty because of their unique features, from execution of the work, time estimation, inspection and assessment to fund allocation. Therefore, a critical step is recognise and categorise the uncertainties associated in bridge building in order to meet project objectives in terms of quality, cost, schedule, environmental, safety, and technical indicators. Various models, however, have been created to detect and prioritise the uncertainty. One of the most commonly used approaches for dealing with uncertainty is the spherical fuzzy set. To formulate an issue, this technique uses a mathematical procedure. The analytic hierarchy process (AHP), on the other hand, is a computer technique that solves a complicated problem by breaking it down into numerous basic problems. A hybrid model based on spherical fuzzy sets and AHP (SAHP) can benefit from both approaches. This study proposes a SAHP based on group decision making (GSAHP) to prioritise the sources of uncertainty in bridge construction projects. Likewise, a modified algorithm is proposed for checking the consistency of the spherical fuzzy matrices. To show the model potential, a real case study is illustrated and evaluated. The model demonstrates its capabilities in modelling uncertainty under an environment with a number of unknown components. The findings reveal that the “delays” factor is of the highest, and the “project team conflicts” parameter is of the least importance. The research findings could be used by decision makers and managers to develop preventive measures

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Field studies on the effects of under sleeper pads in lateral resistance of railway

Under sleeper pads are used in several areas, specially, in places where transfer of vibrations to the surrounding areas should be limited. Beside of all advantages of this elements in the field of reducing costs of repair and maintenance of railway, improvement of line geometry, decreasing the thickness of required ballast, reduction of vibrations and disturbing noises coming from passing trains and increasing trip convenience, use of these pads according to thickness and hardness of them could be effective in lateral resistance. Based on international evaluations in the field of under sleeper pads, results of influence of under sleeper pads in lateral resistance  of railway are various, because of different reasons including: contact quality and compression of ballast grains, ballast thickness, distance between sleepers and different test for estimating the lateral resistance, therefore application of these pads specially in mountainous ways that lateral resistance is important, influence of these pads must be cleared. So in this field of study, lateral resistance of railway is measured by Single Tie Push Test. In this study 150 polyurethane under sleeper pads with two different stiffness which were produced by Getzner Company (specialize in vibration insulation in the rail), used in real line. Results of this field examinations show utilization of these elements under the sleepers increase 9.6% for the lateral resistance when SLB 3007 G (which are stiffer) attached in comparison to sleepers without pad and 2.54%  decrease when SLB 1308 G attached in comparison to sleepers without pad. However decrease in hardness, results in increasing rate of lateral resistance reduction