Search results for "Structural engineering"
showing 10 items of 1998 documents
Role of particle characteristics in the compression behaviour of gap-graded sands
2019
Abstract The compression in gap-graded mixtures of sands with combined mineralogy has been investigated in recent research, focusing on the key factors that might imply the occurrence of convergent or non-convergent paths in compression (i.e., transitional or non-transitional behaviour). From previous work, the mineralogy of a matrix composed of larger grains seems to determine the possibility of the occurrence of transitional behaviour. Hence, if there is a strong and stiff matrix made of quartz sand particles, which are either larger than or at least of similar size to the other component, then non-convergent compression paths (i.e., transitional behaviour) are likely to occur. As a furth…
Seismic behavior of structures equipped with variable friction dissipative (VFD) systems
2021
Usually, to mitigate the stresses in framed structures, different strategies are used. Among them, base isolation, viscous/friction/metallic yielding dampers and tuned mass dumpers have been widely investigated. Fluid Viscous Dampers (FVD) probably result the most diffused for the simplicity in the applications. However, these type of dampers request limited interstorey drifts to avoid dangerous effects. Further, they have an elevate cost. On the contrary, friction dampers are not so expensive but request high interstorey drifts to give a significant contribute in the dissipation of energy during an earthquake. In this paper an approach for the energy dissipation by friction, modified with …
Successful aerobic bioremediation of groundwater contaminated with higher chlorinated phenols by indigenous degrader bacteria
2018
The xenobiotic priority pollutant pentachlorophenol has been used as a timber preservative in a polychlorophenol bulk synthesis product containing also tetrachlorophenol and trichlorophenol. Highly soluble chlorophenol salts have leaked into groundwater, causing severe contamination of large aquifers. Natural attenuation of higher-chlorinated phenols (HCPs: pentachlorophenol + tetrachlorophenol) at historically polluted sites has been inefficient, but a 4-year full scale in situ biostimulation of a chlorophenol-contaminated aquifer by circulation and re-infiltration of aerated groundwater was remarkably successful: pentachlorophenol decreased from 400 μg L−1 to <1 μg L−1 and tetrachlorophen…
Chip Formation and Control
2008
This chapter provides comprehensive engineering knowledge and modelling techniques applied in description of chip formation in the cutting zone and its separation from the bulk material, flow, and final breaking. Possible classification systems, including different chip shapes and physical mechanisms of their formation, are specified. The mechanisms of brittle fracture-based and shear-type chips are characterized in terms of plastic deformation and fracture mechanics. The models of the shear angle using different mechanical approaches are discussed. In addition, representative examples of FEM simulations of different types of chips for turning and milling operations are presented. Formulas …
The best way to assess visually induced motion sickness in a fixed-base driving simulator
2017
Abstract Objective Driving simulator usage is becoming more widespread, yet many users still experience substantial motion sickness-like symptoms induced by optical flow, called visually induced motion sickness (VIMS). The Fast Motion sickness Scale (FMS) allows for continuous on-line assessment of VIMS. Using mixed models for ordinal data, this study investigated how to optimally analyze FMS data, and then used the resulting models to examine the development of symptoms over time in detail. Additionally, the study explored the impact of specific VIMS-inducing road elements. Methods Twenty-eight healthy young adults without prior simulator experience completed six courses on two days in a f…
Variable Fixing for Two-Arc Sequences in Branch-Price-and-Cut Algorithms on Path-Based Models
2020
Variable fixing by reduced costs is a popular technique for accelerating the solution process of mixed-integer linear programs. For vehicle-routing problems solved by branch-price-and-cut algorithms, it is possible to fix to zero the variables associated with all routes containing at least one arc from a subset of arcs determined according to the dual solution of a linear relaxation. This is equivalent to removing these arcs from the network used to generate the routes. In this paper, we extend this technique to routes containing sequences of two arcs. Such sequences or their arcs cannot be removed directly from the network because routes traversing only one arc of a sequence might still b…
The facility location problem with capacity transfers
2020
Abstract This paper explores the concept of capacity transfer in the context of capacitated facility location problems. This is accomplished by assuming that facilities with surplus capacity/production can cooperate with those facing shortage by transferring part of that capacity/production. Such a transfer incurs a cost that nonetheless may be compensated by savings both in the installation costs and in the distribution costs. Mixed-integer mathematical programming models are proposed for the problem. A distinction is made between the case in which the triangle inequality holds for the transfer costs and the case in which it does not. We present compact models, which are enhanced with vali…
From bus to tramway: Is there an economic impact of substituting a rapid mass transit system? An empirical investigation accounting for anticipation …
2018
Abstract Hedonic pricing models and price equations have been extensively used to retrieve the implicit prices of urban externalities through real estate markets. Many applications have been devoted to investigating the impact of new mass transit systems, such as rail infrastructures. However, the implementation of such infrastructures usually takes some time and markets can react with an anticipation effect that can vary according to the different development phases. Moreover, the impact may be different if it acts as a substitute to existing rapid transit services. This paper focuses on the impact of substituting bus rapid transit (BRT) for light rail transit (LRT) services, taking into a…
Effectiveness and user acceptance of infotainment-lockouts: A driving simulator study
2019
Abstract Lockout is a system-initiated distraction mitigation strategy that renders certain features of in-vehicle information systems (IVISs) non operable while the vehicle is in motion. The aim of this driving simulator study was to examine the influence of lockouts on driving performance and user acceptance. Overall, 52 participants performed six tasks with fully unlocked, partially locked, and completely locked IVIS. Within a repeated-measures design, we assessed user acceptance. As participants were free to decide where to conduct a secondary task, we could only analyse driving performance of 26 drivers. After each driving section, the participants rated the respective system with resp…
Psychosocial factors associated with helmet use by adult cyclists
2019
Abstract: This study examines beliefs about helmet use in adult cyclists from 17 countries participating in the COST Action TU1101 Project (Helmet Optimization in Europe – HOPE). A total of 5797 respondents were included in the analysis after applying eligibility criteria and data cleaning. Cyclists' beliefs were assessed by 25 items using a 7-point Likert scale. These items were factor analyzed resulting in a four-factor solution (Factor 1: Perceived Benefits and Risk Reduction, Factor 2: Perceived Disadvantages and Barriers to Helmet Use, Factor 3: Perception of Group Norms, and Factor 4: Situation-Dependence of Helmet Use). Results show that both beliefs and helmet wearing behavior diffe…