scholarly journals Large-scale triaxial and box testing on railroad ballast: a review

2019 ◽  
Vol 1 (12) ◽  
Author(s):  
Yahia Alabbasi ◽  
Mohammed Hussein
Keyword(s):  
Mechanical Behavior ◽  
Large Scale ◽  
Experimental Approach ◽  
Load Condition ◽  
Experimental Tests ◽  
Basic Element ◽  
Transportation Systems ◽  
Extensive Literature ◽  
Railway Transportation ◽  
Set Up

Abstract The use of railway transportation systems has been increased throughout the years. The conventional ballasted tracks have been used widely in many countries around the world. Ballast material is the basic element of ballasted tracks. Ballast degrades and deforms after service. Therefore, periodical ballast maintenance is needed which is a cost and time expensive activity. Understanding ballast mechanical behavior leads to better design and efficient maintenance. From the literature, experimental approach is used to understand the mechanical behavior of railroad ballast. Traditional experimental tests provide inaccurate results due to the large ballast particle size with relative to sample size. Researchers used large scale triaxial and box tests extensively to understand the mechanical behavior of railroad ballast. The target of this paper is to present a concise review of the extensive literature presented on the mechanical behavior of railroad ballast using large scale triaxial and box testing. It discusses the various aspects of large-scale equipment such as apparatus’ set-up, size, material and shape, simulated load condition and test purpose. It presents the key findings of the large-scale triaxial and box tests in understanding ballast mechanical behavior.

scholarly journals Electromagnetic Energy Harvesting Technology: Key to Sustainability in Transportation Systems

2019 ◽  
Vol 11 (18) ◽  
pp. 4906 ◽  
Author(s):  
Mohammadreza Gholikhani ◽  
Seyed Amid Tahami ◽  
Mohammadreza Khalili ◽  
Samer Dessouky
Keyword(s):  
Energy Harvesting ◽  
Large Scale ◽  
Scale Effects ◽  
Electrical Power ◽  
Experimental Tests ◽  
Transportation Systems ◽  
Electromagnetic Energy ◽  
Sustainable Transportation ◽  
Traffic Conditions ◽  
Electromagnetic Energy Harvesting

The convergence of concerns about environmental quality, economic vitality, social equity, and climate change have led to vast interest in the concept of sustainability. Energy harvesting from roadways is an innovative way to provide green and renewable energy for sustainable transportation. However, energy harvesting technologies are in their infancy, so limited studies were conducted to evaluate their performance. This article introduces innovative electromagnetic energy harvesting technology that includes two different mechanisms to generate electrical power: a cantilever generator mechanism and a rotational mechanism. Laboratory experimental tests were conducted to examine the performance of the two mechanisms in generating power under different simulated traffic conditions. The experimental results had approximately root mean square power 0.43 W and 0.04 W and maximum power of 2.8 W and 0.25 W for cantilever and rotational, respectively. These results showed promising capability for both mechanisms in generating power under real traffic conditions. In addition, the study revealed the potential benefits of energy harvesting from roadways to support sustainability in transportation systems. Overall, the findings show that energy harvesting can impact sustainable transportation systems significantly. However, further examination of the large-scale effects of energy harvesting from roadways on sustainability is needed.

scholarly journals A FEM-Experimental Approach for the Development of a Conceptual Linear Actuator Based on Tendril’s Free Coiling

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Luca Cortese ◽  
Selena Milanovic ◽  
Renato Vidoni
Keyword(s):  
Experimental Approach ◽  
Experimental Tests ◽  
Nickel Titanium ◽  
Linear Actuator ◽  
The Finite Element Method ◽  
Actual Performance ◽  
Suitable Material ◽  
Working Principle ◽  
Set Up ◽  
Prototype Design

Within the vastness of the plant species, certain living systems show tendril structures whose motion is of particular interest for biomimetic engineers. Tendrils sense and coil around suitable grips, and by shortening in length, they erect the remaining plant body. To achieve contraction, tendrils rotate along their main axis and shift from a linear to a double-spring geometry. This phenomenon is denoted as the free-coiling phase. In this work, with the aim of understanding the fundamentals of the mechanics behind the free coiling, a reverse-engineering approach based on the finite element method was firstly applied. The model consisted of an elongated cylinder with suitable material properties, boundary, and loading conditions, in order to reproduce the kinematics of the tendril. The simulation succeeded in mimicking coiling faithfully and was therefore used to validate a tentative linear actuator model based on the plant’s working principle. More in detail, exploiting shape memory alloy materials to obtain large reversible deformations, the main tendril features were implemented into a nickel-titanium spring-based testing model. The results of the experimental tests confirmed the feasibility of the idea in terms of both functioning principles and actual performance. It can be concluded that the final set-up can be used as a base for a prototype design of a new kind of a linear actuator.

scholarly journals Risk Prioritization for Failure Modes in Mining Railcars

2021 ◽  
Vol 13 (11) ◽  
pp. 6195
Author(s):  
Mohammad Javad Rahimdel ◽  
Behzad Ghodrati
Keyword(s):  
Large Scale ◽  
Failure Modes ◽  
Transportation Systems ◽  
Control Measures ◽  
Rolling Stock ◽  
Railway Transportation ◽  
Effect Analysis ◽  
Risk Prioritization ◽  
Fuzzy Environment ◽  
Hierarchy Process

Railway transportation systems are generally used to transport minerals from large-scale mines. Any failure in the railcar components may cause delays or even catastrophic derailment accidents. Failure mode and effect analysis (FMEA) is an effective tool for the risk assessment of mechanical systems. This method is an appropriate approach to identify the critical failure modes and provide proper control measures to reduce the level of risk. This research aims to propose an approach to identify and prioritize the failure modes based on their importance degree. To achieve this, the analytical hierarchy process (AHP) is used along with the FMEA. To compensate for the scarcities of the conventional FMEA in using the linguistic variables, the proposed approach is developed under the fuzzy environment. The proposed approach was applied in a case study, a rolling stock operated in an iron ore mine located in Sweden. The results of this study are helpful to identify not only the most important failure modes but also the most serious and critical ones.

scholarly journals Experimental Approach for Printability Assessment: Toward a Practical Decision-Making Framework of Printability for Cementitious Materials

Buildings ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 245 ◽  
Author(s):  
Zoubeir Lafhaj ◽  
Andry Zaid Rabenantoandro ◽  
Soufiane el Moussaoui ◽  
Zakaria Dakhli ◽  
Nicolas Youssef
Keyword(s):  
Large Scale ◽  
Experimental Approach ◽  
Experimental Tests ◽  
Cementitious Materials ◽  
Optimal Time ◽  
Cone Penetrometer ◽  
Large Scale Geometry ◽  
Material Formulation ◽  
Printing System ◽  
Interval Ratio

The objective of this paper is to propose a pre-experimental framework of printability pre-assessment of cementitious materials. This study firstly presents a general review of additive manufacturing in construction and then examines the main characteristic of the material formulation and printability properties based on extrusion technique. This framework comes with experimental tests to determine a qualitative printability index of mixtures. It uses mix-designs reported in the literature to define interval ratio of mixture design to be investigated in this study. The focus was put on two criteria that influence the formulation namely flowability and buildability. Two practiced based tests, mini slump and cone penetrometer, were used to draw the flowability and buildability dimensionless index. The results were analyzed by introducing an optimal printability coefficient and examining their time evolution. An optimal time of printing was determined Toptimal. Finally, a 3D mortar printing system and its operational process are presented. Then, based on the measurement, the optimal mixture is identified and printed in a large-scale geometry.

The Problem of Distributed Wireless Sensors Positioning in the Mobile Spatial Coordinate Measuring System (MSCMS)

2008 ◽  
Author(s):  
Fiorenzo Franceschini ◽  
Maurizio Galetto ◽  
Domenico Maisano ◽  
Luca Mastrogiacomo
Keyword(s):  
Large Scale ◽  
Ad Hoc ◽  
Experimental Tests ◽  
Measuring System ◽  
Opening Angle ◽  
Computer Assisted ◽  
Spatial Coordinate ◽  
Measured Object ◽  
Working Volume ◽  
Set Up

Mobile Spatial coordinate Measuring System (MScMS) is a wireless-sensor-network based system developed at the Industrial Metrology and Quality Engineering Laboratory of DISPEA – Politecnico di Torino. It has been designed to perform simple and rapid indoor dimensional measurements of medium-large size objects (large scale metrology). It is made up of three basic parts: a “constellation” of wireless devices (Crickets), a mobile probe, and a PC to store and elaborate data. Crickets and mobile probe use ultrasound (US) transceivers in order to evaluate mutual distances. Each US device has a communication range limited by a cone of transmission within a nominal opening angle of about 170° and a maximum distance of no more than 8 m. The mobile probe location in the working volume is obtained by a trilateration, consequently it should communicate with at least 4 constellation devices at once. The system makes it possible to calculate the position — in terms of spatial coordinates — of the object points “touched” by the probe. Acquired data are then available for different types of elaboration (determination of distances, curves or surfaces of measured objects). During the system set-up, the constellation Crickets (beacons) are manually placed in the working volume (we define this operation as “positioning”). After that, their coordinates are determined as much precisely as possible (this operation is said “location”). The positioning of constellation devices is one of the most critical aspects in the system set-up. In principle, Crickets can be arranged without restrictions all around the measured object. However, the number and position of network devices are strongly related to the dimensions and shape of both the measuring volume and the measured object. The accuracy in the location of constellation devices is fundamental for the accuracy of the coordinates of the touched points during measurement operation. It is important to assure a full coverage of the space served by network devices by a proper alignment of US transmitters. For that reason, an ad hoc software “pre-processor” has been developed in order to help the operator in positioning and locating constellation devices in the working volume, according to the measuring space and the measured object dimensional characteristics. The aim of the paper is to introduce and describe this computer-assisted approach. Some preliminary results of experimental tests carried out on the system prototype are also presented and discussed.

Platelet Anti-Aggregating Activity and Tolerance of Clopidogrel in Atherosclerotic Patients

1996 ◽  
Vol 76 (06) ◽  
pp. 0939-0943 ◽  
Author(s):  
B Boneu ◽  
G Destelle ◽  
Keyword(s):  
Platelet Aggregation ◽  
Large Scale ◽  
Bleeding Time ◽  
Antithrombotic Activity ◽  
Ambulatory Patients ◽  
Patients At Risk ◽  
Set Up ◽  
Ischemic Events ◽  
Large Scale Clinical Trial ◽  
Selection Of

SummaryThe anti-aggregating activity of five rising doses of clopidogrel has been compared to that of ticlopidine in atherosclerotic patients. The aim of this study was to determine the dose of clopidogrel which should be tested in a large scale clinical trial of secondary prevention of ischemic events in patients suffering from vascular manifestations of atherosclerosis [CAPRIE (Clopidogrel vs Aspirin in Patients at Risk of Ischemic Events) trial]. A multicenter study involving 9 haematological laboratories and 29 clinical centers was set up. One hundred and fifty ambulatory patients were randomized into one of the seven following groups: clopidogrel at doses of 10, 25, 50,75 or 100 mg OD, ticlopidine 250 mg BID or placebo. ADP and collagen-induced platelet aggregation tests were performed before starting treatment and after 7 and 28 days. Bleeding time was performed on days 0 and 28. Patients were seen on days 0, 7 and 28 to check the clinical and biological tolerability of the treatment. Clopidogrel exerted a dose-related inhibition of ADP-induced platelet aggregation and bleeding time prolongation. In the presence of ADP (5 \lM) this inhibition ranged between 29% and 44% in comparison to pretreatment values. The bleeding times were prolonged by 1.5 to 1.7 times. These effects were non significantly different from those produced by ticlopidine. The clinical tolerability was good or fair in 97.5% of the patients. No haematological adverse events were recorded. These results allowed the selection of 75 mg once a day to evaluate and compare the antithrombotic activity of clopidogrel to that of aspirin in the CAPRIE trial.

A reconnaissance of tropical resources during Revolutionary years: the role of the Paris Museum d'Histoire Naturelle

1991 ◽  
Vol 18 (3) ◽  
pp. 333-362 ◽  
Author(s):  
MADELEINE LY-TIO-FANE
Keyword(s):  
South Africa ◽  
Natural History ◽  
Scientific Research ◽  
Extensive Literature ◽  
War Of Independence ◽  
Leading Role ◽  
Scientific Principles ◽  
Set Up ◽  
Joseph Ii

SUMMARY The recent extensive literature on exploration and the resulting scientific advances has failed to highlight the contribution of Austrian enterprise to the study of natural history. The leading role of Joseph II among the neutral powers which assumed the carrying trade of the belligerents during the American War of Independence, furthered the development of collections for the Schönbrunn Park and Gardens which had been set up on scientific principles by his parents. On the conclusion of peace, Joseph entrusted to Professor Maerter a world-encompassing mission in the course of which the Chief Gardener Franz Boos and his assistant Georg Scholl travelled to South Africa to collect plants and animals. Boos pursued the mission to Isle de France and Bourbon (Mauritius and Reunion), conveyed by the then unknown Nicolas Baudin. He worked at the Jardin du Roi, Pamplemousses, with Nicolas Cere, or at Palma with Joseph Francois Charpentier de Cossigny. The linkage of Austrian and French horticultural expertise created a situation fraught with opportunities which were to lead Baudin to the forefront of exploration and scientific research as the century closed in the upheaval of the Revolutionary Wars.

MODELING THE SOUTH ATLANTIC OCEAN FROM MEDIUM TO HIGH RESOLUTION

2014 ◽  
Vol 31 (2) ◽  
Author(s):  
Mariela Gabioux ◽  
Vladimir Santos da Costa ◽  
Joao Marcos Azevedo Correia de Souza ◽  
Bruna Faria de Oliveira ◽  
Afonso De Moraes Paiva
Keyword(s):  
High Resolution ◽  
Atlantic Ocean ◽  
Large Scale ◽  
South Atlantic ◽  
Surface Relaxation ◽  
The South ◽  
Small Surface ◽  
Basic Model ◽  
Basic Set ◽  
Set Up

Results of the basic model configuration of the REMO project, a Brazilian approach towards operational oceanography, are discussed. This configuration consists basically of a high-resolution eddy-resolving, 1/12 degree model for the Metarea V, nested in a medium-resolution eddy-permitting, 1/4 degree model of the Atlantic Ocean. These simulations performed with HYCOM model, aim for: a) creating a basic set-up for implementation of assimilation techniques leading to ocean prediction; b) the development of hydrodynamics bases for environmental studies; c) providing boundary conditions for regional domains with increased resolution. The 1/4 degree simulation was able to simulate realistic equatorial and south Atlantic large scale circulation, both the wind-driven and the thermohaline components. The high resolution simulation was able to generate mesoscale and represent well the variability pattern within the Metarea V domain. The BC mean transport values were well represented in the southwestern region (between Vitória-Trinidade sea mount and 29S), in contrast to higher latitudes (higher than 30S) where it was slightly underestimated. Important issues for the simulation of the South Atlantic with high resolution are discussed, like the ideal place for boundaries, improvements in the bathymetric representation and the control of bias SST, by the introducing of a small surface relaxation. In order to make a preliminary assessment of the model behavior when submitted to data assimilation, the Cooper & Haines (1996) method was used to extrapolate SSH anomalies fields to deeper layers every 7 days, with encouraging results.

scholarly journals Vibration characteristics of triple-gear-rotor system in compressed air energy storage under variable torque load

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042098705
Author(s):  
Xinran Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xuehui Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Element Model ◽  
Rotor System ◽  
Dynamic Responses ◽  
System Response ◽  
Rotating Speed ◽  
Torque Load ◽  
Set Up ◽  
Two Stages

This paper focuses on the effects of the off-design operation of CAES on the dynamic characteristics of the triple-gear-rotor system. A finite element model of the system is set up with unbalanced excitations, torque load excitations, and backlash which lead to variations of tooth contact status. An experiment is carried out to verify the accuracy of the mathematical model. The results show that when the system is subjected to large-scale torque load lifting at a high rotating speed, it has two stages of relatively strong periodicity when the torque load is light, and of chaotic when the torque load is heavy, with the transition between the two states being relatively quick and violent. The analysis of the three-dimensional acceleration spectrum and the meshing force shows that the variation in the meshing state and the fluctuation of the meshing force is the basic reasons for the variation in the system response with the torque load. In addition, the three rotors in the triple-gear-rotor system studied show a strong similarity in the meshing states and meshing force fluctuations, which result in the similarity in the dynamic responses of the three rotors.

scholarly journals Environmental Engineering Techniques to Restore Degraded Posidonia oceanica Meadows

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 661
Author(s):  
Luigi Piazzi ◽  
Stefano Acunto ◽  
Francesca Frau ◽  
Fabrizio Atzori ◽  
Maria Francesca Cinti ◽  
...  
Keyword(s):  
Large Scale ◽  
Natural Habitat ◽  
Cost Benefit ◽  
Cost Effective ◽  
Posidonia Oceanica ◽  
Environmental Engineering ◽  
Bottom Surface ◽  
Sessile Invertebrates ◽  
Set Up ◽  
Short Time

Seagrass planting techniques have shown to be an effective tool for restoring degraded meadows and ecosystem function. In the Mediterranean Sea, most restoration efforts have been addressed to the endemic seagrass Posidonia oceanica, but cost-benefit analyses have shown unpromising results. This study aimed at evaluating the effectiveness of environmental engineering techniques generally employed in terrestrial systems to restore the P. oceanica meadows: two different restoration efforts were considered, either exploring non-degradable mats or, for the first time, degradable mats. Both of them provided encouraging results, as the loss of transplanting plots was null or very low and the survival of cuttings stabilized to about 50%. Data collected are to be considered positive as the survived cuttings are enough to allow the future spread of the patches. The utilized techniques provided a cost-effective restoration tool likely affordable for large-scale projects, as the methods allowed to set up a wide bottom surface to restore in a relatively short time without any particular expensive device. Moreover, the mats, comparing with other anchoring methods, enhanced the colonization of other organisms such as macroalgae and sessile invertebrates, contributing to generate a natural habitat.

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