scholarly journals Impact of Vlasov Foundation Parameters on the Deflection of a Non-uniform Timoshenko Beam Subject to a Moving Load

2019 ◽  
Author(s):  
Magdalena Ataman
Keyword(s):  
Timoshenko Beam ◽  
Moving Load ◽  
Free Vibrations ◽  
Problem Solution ◽  
Moving Force ◽  
Dynamic Factors ◽  
Modulus Problem ◽  
Foundation Parameters ◽  
The Impact ◽  
Selection Of

Subject of the study is a Timoshenko beam with transverse-variable Young’s modulus. Problem of vibrations of the beam resting on an inertial Vlasov foundation and subjected to a moving force is solved analytically. The Timoshenko beam’s eigenproblem is discussed and the physical sense of the additional band of natural vibrations and the corresponding critical frequency is analytically explained. The impact of the foundation and its parameters on the Timoshenko beam’s vibrations forced by moving force is investigated. Dynamic factors relating to beam deflections are analyzed. Two vibration cases are discussed: forced vibrations (when a moving force is applied to the beam) and free vibrations (after the moving force has been left the beam). The damping effect on vibration is taken into account in the problem solution. The results indicate that appropriate selection of the foundation’s parameters allows for the beam deflection’s significant reduction, while the impact of the shear coefficient in the foundation on the reduction is more pronounced than the impact of other factors.

scholarly journals Vibrations of a Timoshenko beam on an inertial foundation under a moving load

2018 ◽  
Vol 196 ◽  
pp. 01056
Author(s):  
Magdalena Ataman
Keyword(s):  
Timoshenko Beam ◽  
Moving Load ◽  
Equations Of Motion ◽  
Free Vibrations ◽  
Forced Vibrations ◽  
Governing Equations ◽  
Concentrated Load ◽  
Numerical Example ◽  
Moving Force ◽  
Speed Response

In the paper vibrations of the Timoshenko beam on an inertial foundation subjected to a moving force are discussed. Considered model of the inertial foundation is described by three parameters. They take into account elasticity, shear and inertia of the subgrade. In the literature such model of the subgrade is called Vlasov or Vlasov-Leontiev model. The Timoshenko beam is traversed by a concentrated load, moving with uniform speed. Response of the beam is found from the governing equations of motion of the problem. Problem of forced vibrations and problem of free vibrations of the beam are solved. Damping of the system is taken into consideration. Solution of the problem is illustrated by numerical example.

scholarly journals Selection of the set of areal units for economic regional research on the land use: a proposal for Aggregation Problem solution

2021 ◽  
pp. 222-234
Keyword(s):  
Spatial Data ◽  
Research Field ◽  
Point Of View ◽  
Added Value ◽  
Necessary Condition ◽  
Problem Solution ◽  
Scientific Disciplines ◽  
Aggregation Problem ◽  
The Impact ◽  
Selection Of

The knowledge of the spatial development of phenomena is crucial in the case of research in economics, geological survey, mining, earth resources and geography. In the literature one can diagnose an important methodological and implementation gap concerning the selection of the set of areal units within the Aggregation Problem. The issue relates to determining boundaries of areal units (regions), whose properties are described by spatial data. The boundaries of areas should be established in such a way that a given analyzed phenomenon is influenced by the same main causes. Only in this case, the analyzed spatial data will properly reflect the impact of main causes, the properties of phenomena and dependencies between them. This means that determining the proper boundaries of areas is a necessary condition for receiving correct conclusions (e.g. delimiting metropolitan areas, assessing mineral resource potential and deposits, or assessing the dynamics of surface processes). From this perspective, the main objective of the article is presenting the proposal for solving the Aggregation Problem, where as the case study the economic analysis of agrarian resources and structure is used. The solution to the problem will lead to establishing the system of macroregions, where the obtained proposal of a system of four sets of areal units is important from the point of view of spatial research. The main added value of the research and its specific contribution to the literature is based on the fact that the proposed solution to the Aggregation Problem can be considered as universal, which is not limited to selected scientific disciplines. The methodology presented in the article can be effectively applied to other spatial research in the field of geology and mining, where the most appropriate research field is the issue of locating areas with appropriate properties or areas which are affected by given analised phenomena.

Dynamic Response of a Timoshenko Beam to a Moving Force

2008 ◽  
Vol 75 (2) ◽  
Author(s):  
Paweł Śniady
Keyword(s):  
Closed Form ◽  
Cross Section ◽  
Timoshenko Beam ◽  
Constant Velocity ◽  
Free Vibrations ◽  
Dynamical Response ◽  
Transverse Displacement ◽  
Closed Form Solutions ◽  
Simply Supported ◽  
Moving Force

We consider the dynamical response of a finite, simply supported Timoshenko beam loaded by a force moving with a constant velocity. The classical solution for the transverse displacement and the rotation of the cross section of a Timoshenko beam has a form of a sum of two infinite series, one of which represents the force vibrations (aperiodic vibrations) and the other one free vibrations of the beam. We show that one of the series, which represents aperiodic (force) vibrations of the beam, can be presented in a closed form. The closed form solutions take different forms depending if the velocity of the moving force is smaller or larger than the velocities of certain shear and bar velocities.

scholarly journals The Anti-Resonance Criterion in Selecting Pick Systems for Fully Operational Cutting Machinery Used in Mining

2017 ◽  
Vol 62 (4) ◽  
pp. 775-793 ◽  
Author(s):  
Piotr Cheluszka
Keyword(s):  
Dynamic Properties ◽  
Free Vibrations ◽  
Correct Selection ◽  
Cutting Head ◽  
Load Carrying ◽  
Mining Machinery ◽  
Main Components ◽  
The Impact ◽  
Cutting System ◽  
Selection Of

Abstrat This article discusses the issue of selecting a pick system for cutting mining machinery, concerning the reduction of vibrations in the cutting system, particularly in a load-carrying structure at work. Numerical analysis was performed on a telescopic roadheader boom equipped with transverse heads. A frequency range of the boom’s free vibrations with a set structure and dynamic properties were determined based on a dynamic model. The main components excited by boom vibrations, generated through the process of cutting rock, were identified. This was closely associated with the stereometry of the cutting heads. The impact on the pick system (the number of picks and their arrangement along the side of the cutting head) was determined by the intensity of the external boom load elements, especially in resonance zones. In terms of the anti-resonance criterion, an advantageous system of cutting head picks was determined as a result of the analysis undertaken. The correct selection of the pick system was ascertained based on a computer simulation of the dynamic loads and vibrations of a roadheader telescopic boom.

scholarly journals Amplification Factors in the Case of Beam Under Moving Force – Theoretical Analysis

2019 ◽  
Vol 65 (1) ◽  
pp. 83-96
Author(s):  
M. Ataman
Keyword(s):  
Moving Load ◽  
Resonance Phenomenon ◽  
Winkler Foundation ◽  
Bending Moments ◽  
Shear Forces ◽  
Engineering Structures ◽  
Amplification Factors ◽  
Moving Force ◽  
Dynamic Amplification ◽  
The Impact

AbstractThe impact of a moving load speed on the dynamic overload of beams, assuming that the track of the load has no unevenness, is examined. First the problem of a visco-elastic beam on a Winkler foundation subjected to a force moving at a constant speed will be solved. Using the Bubnov-Galerkin method, the deflections of the beam, and then the bending moments and shear forces will be determined. The solution of the problem will be obtained both for the case of a forced vibration and the case of a free vibration after the moving force has left the beam. Using these solutions, dynamic amplification factors will be determined for the deflections, bending moments, and shear forces, which are different for the two cases.The magnitude of the amplification factors increases and decreases alternately as a function of the speed. In the case of a single force on a beam, the dynamic overloads are limited, and do not exceed 60%. There is no resonance phenomenon in the beam subjected to the single moving force. The dynamic amplification factors determined in this way can be used as correction coefficients when designing engineering structures subjected to moving loads by static methods.

Methods for Restricting Maximum Exposure Rate in Computerized Adaptative Testing

Methodology ◽  
2007 ◽  
Vol 3 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Juan Ramon Barrada ◽  
Julio Olea ◽  
Vicente Ponsoda
Keyword(s):  
Measurement Accuracy ◽  
Computerized Adaptive Testing ◽  
Computation Time ◽  
Adaptive Testing ◽  
Exposure Rate ◽  
Control Parameters ◽  
The Impact ◽  
Two Alternatives ◽  
Selection Of ◽  
Maximum Exposure

Abstract. The Sympson-Hetter (1985) method provides a means of controlling maximum exposure rate of items in Computerized Adaptive Testing. Through a series of simulations, control parameters are set that mark the probability of administration of an item on being selected. This method presents two main problems: it requires a long computation time for calculating the parameters and the maximum exposure rate is slightly above the fixed limit. Van der Linden (2003) presented two alternatives which appear to solve both of the problems. The impact of these methods in the measurement accuracy has not been tested yet. We show how these methods over-restrict the exposure of some highly discriminating items and, thus, the accuracy is decreased. It also shown that, when the desired maximum exposure rate is near the minimum possible value, these methods offer an empirical maximum exposure rate clearly above the goal. A new method, based on the initial estimation of the probability of administration and the probability of selection of the items with the restricted method ( Revuelta & Ponsoda, 1998 ), is presented in this paper. It can be used with the Sympson-Hetter method and with the two van der Linden's methods. This option, when used with Sympson-Hetter, speeds the convergence of the control parameters without decreasing the accuracy.

Impact of removing ESBL designation from culture reports on the selection of antibiotics for the treatment of infections associated with ESBL-producing organisms

2020 ◽  
Vol 41 (5) ◽  
pp. 604-607 ◽  
Author(s):  
Mark D. Lesher ◽  
Cory M. Hale ◽  
Dona S. S. Wijetunge ◽  
Matt R. England ◽  
Debra S. Myers ◽  
...  
Keyword(s):  
Antimicrobial Stewardship ◽  
Antibiotic Prescribing ◽  
The Impact ◽  
Inhibitor Combination ◽  
Lactamase Inhibitor ◽  
Selection Of

AbstractWe characterized the impact of removal of the ESBL designation from microbiology reports on inpatient antibiotic prescribing. Definitive prescribing of carbapenems decreased from 48.4% to 16.1% (P = .01) and β-lactam–β-lactamase inhibitor combination increased from 19.4% to 61.3% (P = .002). Our findings confirm the importance of collaboration between microbiology and antimicrobial stewardship programs.

scholarly journals The Impact of Alkaloid-Producing Epichloë Endophyte on Forage Ryegrass Breeding: A New Zealand Perspective

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 158
Author(s):  
Colin Eady
Keyword(s):  
Seed Production ◽  
Health Issues ◽  
Abiotic Stressors ◽  
Livestock Health ◽  
The Right ◽  
The Impact ◽  
The Relationship ◽  
And Storage ◽  
Selection Of ◽  
Epichloë Endophyte

For 30 years, forage ryegrass breeding has known that the germplasm may contain a maternally inherited symbiotic Epichloë endophyte. These endophytes produce a suite of secondary alkaloid compounds, dependent upon strain. Many produce ergot and other alkaloids, which are associated with both insect deterrence and livestock health issues. The levels of alkaloids and other endophyte characteristics are influenced by strain, host germplasm, and environmental conditions. Some strains in the right host germplasm can confer an advantage over biotic and abiotic stressors, thus acting as a maternally inherited desirable ‘trait’. Through seed production, these mutualistic endophytes do not transmit into 100% of the crop seed and are less vigorous than the grass seed itself. This causes stability and longevity issues for seed production and storage should the ‘trait’ be desired in the germplasm. This makes understanding the precise nature of the relationship vitally important to the plant breeder. These Epichloë endophytes cannot be ‘bred’ in the conventional sense, as they are asexual. Instead, the breeder may modulate endophyte characteristics through selection of host germplasm, a sort of breeding by proxy. This article explores, from a forage seed company perspective, the issues that endophyte characteristics and breeding them by proxy have on ryegrass breeding, and outlines the methods used to assess the ‘trait’, and the application of these through the breeding, production, and deployment processes. Finally, this article investigates opportunities for enhancing the utilisation of alkaloid-producing endophytes within pastures, with a focus on balancing alkaloid levels to further enhance pest deterrence and improving livestock outcomes.

scholarly journals An IoT-Based Participatory Antitheft System for Public Safety Enhancement in Smart Cities

Smart Cities ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 919-937
Author(s):  
Nikos Papadakis ◽  
Nikos Koukoulas ◽  
Ioannis Christakis ◽  
Ilias Stavrakas ◽  
Dionisis Kandris
Keyword(s):  
Smart Cities ◽  
Low Cost ◽  
Negative Influence ◽  
Asset Tracking ◽  
Tracking Tasks ◽  
Tracking Process ◽  
The Impact ◽  
Operation Center ◽  
Safety Enhancement ◽  
Selection Of

The risk of theft of goods is certainly an important source of negative influence in human psychology. This article focuses on the development of a scheme that, despite its low cost, acts as a smart antitheft system that achieves small property detection. Specifically, an Internet of Things (IoT)-based participatory platform was developed in order to allow asset-tracking tasks to be crowd-sourced to a community. Stolen objects are traced by using a prototype Bluetooth Low Energy (BLE)-based system, which sends signals, thus becoming a beacon. Once such an item (e.g., a bicycle) is stolen, the owner informs the authorities, which, in turn, broadcast an alert signal to activate the BLE sensor. To trace the asset with the antitheft tag, participants use their GPS-enabled smart phones to scan BLE tags through a specific smartphone client application and report the location of the asset to an operation center so that owners can locate their assets. A stolen item tracking simulator was created to support and optimize the aforementioned tracking process and to produce the best possible outcome, evaluating the impact of different parameters and strategies regarding the selection of how many and which users to activate when searching for a stolen item within a given area.

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