Nonlinear Modelling and Identification of a Small-Scale Bridge

2008 ◽  
Author(s):  
Jose´ L. Zapico ◽  
David H. Bassir ◽  
Mari´a P. Gonza´lez-Marti´nez ◽  
Marta Garci´a-Die´guez
Keyword(s):  
Experimental Data ◽  
Adaptive Sampling ◽  
Dynamic Modelling ◽  
Sampling Technique ◽  
Elastic Stiffness ◽  
Small Scale ◽  
Finite Element Models ◽  
Viscous Damping ◽  
Slip Model ◽  
Linear Elastic

The dynamic modelling and identification of a small-scale bridge is addressed in this paper. Two finite element models with linear elastic stiffness and different damping modelling has been tried. They correspond to a linear viscous damping and a nonlinear elasto-slip one. Both models were fitted to the available experimental data by a novel adaptive sampling technique that was repeated several times. In all the runs the technique yielded consistent results, which confirms its robustness. The elasto-slip model gave excellent fitting to the experimental data, while the results of the linear viscous one were poor.

scholarly journals Impact of Adopting Improved Seeds on Access to Broader Food Groups Among Small-Scale Sorghum Producers in Tanzania

SAGE Open ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 215824402097999
Author(s):  
Aloyce R. Kaliba ◽  
Anne G. Gongwe ◽  
Kizito Mazvimavi ◽  
Ashagre Yigletu
Keyword(s):  
Food Security ◽  
Dietary Diversity ◽  
Sampling Technique ◽  
Inverse Probability Weighting ◽  
Reproductive Age ◽  
Small Scale ◽  
Probability Weighting ◽  
Food Groups ◽  
Inverse Probability ◽  
Double Robust

In this study, we use double-robust estimators (i.e., inverse probability weighting and inverse probability weighting with regression adjustment) to quantify the effect of adopting climate-adaptive improved sorghum varieties on household and women dietary diversity scores in Tanzania. The two indicators, respectively, measure access to broader food groups and micronutrient and macronutrient availability among children and women of reproductive age. The selection of sample households was through a multistage sampling technique, and the population was all households in the sorghum-producing regions of Central, Northern, and Northwestern Tanzania. Before data collection, enumerators took part in a 1-week training workshop and later collected data from 822 respondents using a structured questionnaire. The main results from the study show that the adoption of improved sorghum seeds has a positive effect on both household and women dietary diversity scores. Access to quality food groups improves nutritional status, food security adequacy, and general welfare of small-scale farmers in developing countries. Agricultural projects that enhance access to improved seeds are, therefore, likely to generate a positive and sustainable effect on food security and poverty alleviation in sorghum-producing regions of Tanzania.

Parametric study of multi-story, perforated, partially grouted masonry walls subjected to in-plane cyclic actions

2020 ◽  
Author(s):  
Klaus Medeiros ◽  
Kyle Chavez ◽  
Fernando S. Fonseca ◽  
Guilherme Parsekian ◽  
Nigel G. Shrive
Keyword(s):  
Experimental Data ◽  
Shear Strength ◽  
Aspect Ratio ◽  
Load Capacity ◽  
Axial Stress ◽  
Reinforcement Ratio ◽  
Masonry Walls ◽  
Finite Element Models ◽  
Initial Stiffness ◽  
Vertical Reinforcement

Finite element models were developed to assess the influence of several parameters on the load capacity, deflection, and initial stiffness of multi-story, partially grouted masonry walls with openings. The base model was validated with experimental data from three walls. The analyses indicated that the load capacity of masonry walls was considerably sensitive to the ungrouted and grouted masonry strengths and mortar shear strength; moderately sensitive to the vertical reinforcement ratio and aspect ratio; slightly sensitive to the axial stress; and almost insensitive to the opening size, reinforcement spacing, and horizontal reinforcement ratio. The deflection of the walls had well-defined correlations with the masonry strength, vertical reinforcement, axial stress and aspect ratio. The initial stiffness was especially sensitive to the axial stress and the aspect ratio, but weakly correlated with the opening size, and the spacing and size of the reinforcement.

Topology Synthesis of Compliant Mechanisms for Nonlinear Force-Deflection and Curved Path Specifications

1999 ◽  
Vol 123 (1) ◽  
pp. 33-42 ◽  
Author(s):  
A. Saxena ◽  
G. K. Ananthasuresh
Keyword(s):  
Finite Element ◽  
Linear Models ◽  
Compliant Mechanisms ◽  
Synthesis Method ◽  
Design Sensitivity ◽  
Finite Element Models ◽  
Geometrically Nonlinear ◽  
Linear Elastic ◽  
Nonlinear Design ◽  
Nonlinear Force

Optimal design methods that use continuum mechanics models are capable of generating suitable topology, shape, and dimensions of compliant mechanisms for desired specifications. Synthesis procedures that use linear elastic finite element models are not quantitatively accurate for large displacement situations. Also, design specifications involving nonlinear force-deflection characteristics and generation of a curved path for the output port cannot be realized with linear models. In this paper, the synthesis of compliant mechanisms is performed using geometrically nonlinear finite element models that appropriately account for large displacements. Frame elements are chosen because of ease of implementation of the general approach and their ability to capture bending deformations. A method for nonlinear design sensitivity analysis is described. Examples are included to illustrate the usefulness of the synthesis method.

COMPARATIVE ALLOCATIVE EFFICIENCY AND PROFITABILITY OF DIFFERENT SCALES OF POULTRY-EGG PRODUCTION IN JOS METROPOLIS, PLATEAU STATE, NIGERIA

2021 ◽  
Vol 4 (4) ◽  
pp. 259-273
Author(s):  
Solomon T. Folorunso ◽  
T. Omosebi ◽  
D. A. Agbonika
Keyword(s):  
Egg Production ◽  
Large Scale ◽  
Allocative Efficiency ◽  
Sampling Technique ◽  
Primary Data ◽  
Small Scale ◽  
Stochastic Production Frontier ◽  
Stochastic Production ◽  
Plateau State ◽  
The Government

The study compared the allocative efficiency and profitability of poultry-egg farmers in Jos metropolis of Plateau State, Nigeria, across different scales. To select 143 respondents, a two-stage sampling technique was used.   Using well-structured questionnaire and interview schedules, primary data on socioeconomic variables were collected. Collected data were analyzed using budgetary technique and stochastic production frontier model. Result of allocative efficiency showed the following: The mean allocative efficiency of the small, medium and large scales was 0.68, 0.12 and 0.11 respectively; the minimum allocative efficiency for small, medium and large scales was 0.30, 0.10 and 0.10 respectively. The maximum allocative efficiency was 0.59, 0.18 and 0.11 respectively for small, medium and large scale farmers. The profitability result indicated that egg production for small, medium and large-scale farms was profitable in the study area with N675, 671.79, N4, 897,236.09 and N16, 327,633.66 per farmer. The rate of return on investment per bird was found to be 19.51%, 31.21% and 83.13% respectively for small, medium and large farm sizes. For small, medium and large-scale farmers respectively, the capital turnover per bird was N 1.20, N1.31 and N1.83. Also, the profitability indices for the small, medium and large scales are N0.16, N0.24 and N0.45. The study recommends that; Farmers should be advised to increase production from small scale to large scale through policies that will promote such, special intervention is needed from the government at all levels through farmers’ cooperatives in the area of inputs subsidy, price efficiency of the farmers could

Dynamic Modelling of Small Scale and High Temperature ORC System Using Simulink and CoolProp

2021 ◽  
Author(s):  
Radheesh Dhanasegaran ◽  
Antti Uusitalo ◽  
Teemu Turunen-Saaresti
Keyword(s):  
High Temperature ◽  
Dynamic Modelling ◽  
Small Scale

Accuracy of Failure Criteria Commonly Used for Ship Collision Simulations

2018 ◽  
Author(s):  
R. Villavicencio ◽  
Bin Liu ◽  
Kun Liu
Keyword(s):  
Finite Element ◽  
Failure Criteria ◽  
Small Scale ◽  
Finite Element Models ◽  
Impact Loads ◽  
Large Scatter ◽  
Element Analysis ◽  
Advantages And Disadvantages ◽  
Ship Collision ◽  
Double Hull

The paper summarises observations of the fracture response of small-scale double hull specimens subjected to quasi-static impact loads by means of simulations of the respective experiments. The collision scenarios are used to evaluate the discretisation of the finite element models, and the energy-responses given by various failure criteria commonly selected for collision assessments. Nine double hull specimens are considered in the analysis so that to discuss the advantages and disadvantages of the different failure criterion selected for the comparison. Since a large scatter is observed from the numerical results, a discussion on the reliability of finite element analysis is also provided based on the present study and other research works found in the literature.

Small Scale Contact Conditions for the Linear-Elastic Interface Crack

1988 ◽  
Vol 55 (4) ◽  
pp. 814-817 ◽  
Author(s):  
Peter M. Anderson
Keyword(s):  
Interface Crack ◽  
Growth Parameter ◽  
Small Scale ◽  
Elastic Materials ◽  
Small Scale Yielding ◽  
Contact Conditions ◽  
Linear Elastic ◽  
Elastic Interface ◽  
Scale Yielding ◽  
Anisotropic Elastic

Conditions are discussed for which the contact zone at the tip of a two-dimensional interface crack between anisotropic elastic materials is small. For such “small scale contact” conditions combined with small scale yielding conditions, a stress concentration vector uniquely characterizes the near tip field, and may be used as a crack growth parameter. Representative calculations for an interface crack on a representative Cu grain boundary show small contact conditions to prevail, except possibly under large shearing loads.

scholarly journals Profitability of Small Scale Vegetable Production in Southern District, Botswana

2017 ◽  
Vol 5 (1) ◽  
pp. 35
Author(s):  
Sekgopa T. Kealeboga ◽  
Lagat K. Job ◽  
Tselaesele M. Nelson
Keyword(s):  
Rural Households ◽  
Sampling Technique ◽  
Small Scale ◽  
Vegetable Production ◽  
Eradication Programme ◽  
Gross Margin ◽  
Production Program ◽  
Extreme Poverty ◽  
Pests And Diseases ◽  
Multi Stage

Government determination to eradicate extreme poverty and food insecurity among Batswana through small scale vegetable production program appears not to transform their economic stance. Rural households that are part of Poverty Eradication Programme were investigated to determine if backyard gardens were profitable enough to improve incomes, reduce extreme poverty, and increase food security. The study aimed at analysing profitability and identifying factors that affect profitability of backyard gardening. Multi-stage sampling technique was used to collect data from 100 rural households who are part of the backyard garden scheme. Data was analysed using descriptive statistics, gross margin analysis and regression analysis. Results indicated that backyard gardening was a viable activity though profitability was affected by amount of fertilizer applied, market availability and area planted. Beneficiaries indicated that the production and marketing constraints they faced included pests and diseases, lack of water, lack of market and poor prices. Program leaders must recognize the production and marketing constraints themselves as well as plan for the possibility that continual financial support for investment in the initial years of operation.

Beyond the Known: Detecting Novel Feasible Domains Over an Unbounded Design Space

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Wei Chen ◽  
Mark Fuge
Keyword(s):  
Real World ◽  
Adaptive Sampling ◽  
Design Space ◽  
Fundamental Problem ◽  
Domain Boundary ◽  
Sampling Technique ◽  
Standard Test ◽  
Worst Case ◽  
Trade Offs ◽  
Design Variables

To solve a design problem, sometimes it is necessary to identify the feasible design space. For design spaces with implicit constraints, sampling methods are usually used. These methods typically bound the design space; that is, limit the range of design variables. But bounds that are too small will fail to cover all possible designs, while bounds that are too large will waste sampling budget. This paper tries to solve the problem of efficiently discovering (possibly disconnected) feasible domains in an unbounded design space. We propose a data-driven adaptive sampling technique—ε-margin sampling, which learns the domain boundary of feasible designs and also expands our knowledge on the design space as available budget increases. This technique is data-efficient, in that it makes principled probabilistic trade-offs between refining existing domain boundaries versus expanding the design space. We demonstrate that this method can better identify feasible domains on standard test functions compared to both random and active sampling (via uncertainty sampling). However, a fundamental problem when applying adaptive sampling to real world designs is that designs often have high dimensionality and thus require (in the worst case) exponentially more samples per dimension. We show how coupling design manifolds with ε-margin sampling allows us to actively expand high-dimensional design spaces without incurring this exponential penalty. We demonstrate this on real-world examples of glassware and bottle design, where our method discovers designs that have different appearance and functionality from its initial design set.

scholarly journals Extracting real-crack properties from non-linear elastic behaviour of rocks: abundance of cracks with dominating normal compliance and rocks with negative Poisson ratios

2017 ◽  
Vol 24 (3) ◽  
pp. 543-551 ◽  
Author(s):  
Vladimir Y. Zaitsev ◽  
Andrey V. Radostin ◽  
Elena Pasternak ◽  
Arcady Dyskin
Keyword(s):  
Experimental Data ◽  
Poisson Ratio ◽  
A Priori ◽  
Elastic Behaviour ◽  
Crack Model ◽  
Normal Compliance ◽  
S Wave ◽  
Linear Elastic ◽  
Non Linear ◽  
Linear Elastic Behaviour

Abstract. Results of examination of experimental data on non-linear elasticity of rocks using experimentally determined pressure dependences of P- and S-wave velocities from various literature sources are presented. Overall, over 90 rock samples are considered. Interpretation of the data is performed using an effective-medium description in which cracks are considered as compliant defects with explicitly introduced shear and normal compliances without specifying a particular crack model with an a priori given ratio of the compliances. Comparison with the experimental data indicated abundance (∼ 80 %) of cracks with the normal-to-shear compliance ratios that significantly exceed the values typical of conventionally used crack models (such as penny-shaped cuts or thin ellipsoidal cracks). Correspondingly, rocks with such cracks demonstrate a strongly decreased Poisson ratio including a significant (∼ 45 %) portion of rocks exhibiting negative Poisson ratios at lower pressures, for which the concentration of not yet closed cracks is maximal. The obtained results indicate the necessity for further development of crack models to account for the revealed numerous examples of cracks with strong domination of normal compliance. Discovering such a significant number of naturally auxetic rocks is in contrast to the conventional viewpoint that occurrence of a negative Poisson ratio is an exotic fact that is mostly discussed for artificial structures.

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