scholarly journals Active Control of Stiffness of Tensegrity Plate-like Structures Built with Simplex Modules

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7888
Author(s):  
Paulina Obara ◽  
Justyna Tomasik
Keyword(s):  
Stress State ◽  
Linear Model ◽  
Active Control ◽  
Static Behavior ◽  
Deployable Structures ◽  
Structural Concept ◽  
Non Linear ◽  
Stress States ◽  
Support Conditions ◽  
The Impact

The aim of this study is to prove that it is possible to control the static behavior of tensegrity plate-like structures. This possibility is very important, particularly in the case of deployable structures. Here, we analyze the impact the support conditions of the structure have on the existence of specific characteristics, such as self-stress states and infinitesimal mechanisms, and, consequently, on the active control. Plates built with Simplex modules are considered. Firstly, the presence of the specific characteristics is examined, and a classification is carried out. Next, the influence of the level of self-stress state on the behavior of structures is analyzed. A geometrically non-linear model, implemented in an original program, written in the Mathematica environment, is used. The results confirm the feasibility of the active control of stiffness of tensegrity plate-like structures characterized by the presence of infinitesimal mechanisms. In the case when mechanisms do not exist, structures are insensitive to the initial prestress level. It is possible to control the occurrence of mechanisms by changing the support conditions of the structure. Based on the obtained results, tensegrity is very promising structural concept, applicable in many areas, when conventional solutions are insufficient.

Selection of models to describe the temperature-dependent development of Neoleucinodes elegantalis (Lepidoptera: Crambidae) and its application to predict the species voltinism under future climate conditions

2021 ◽  
pp. 1-9
Author(s):  
Hevellyn Talissa dos Santos ◽  
Cesar Augusto Marchioro
Keyword(s):  
Climate Change ◽  
Linear Model ◽  
Future Climate ◽  
Future Climate Change ◽  
Climate Change Scenarios ◽  
Temperature Dependent ◽  
Dependent Development ◽  
Degree Day ◽  
Non Linear ◽  
The Impact

Abstract The small tomato borer, Neoleucinodes elegantalis (Guenée, 1854) is a multivoltine pest of tomato and other cultivated solanaceous plants. The knowledge on how N. elegantalis respond to temperature may help in the development of pest management strategies, and in the understanding of the effects of climate change on its voltinism. In this context, this study aimed to select models to describe the temperature-dependent development rate of N. elegantalis and apply the best models to evaluate the impacts of climate change on pest voltinism. Voltinism was estimated with the best fit non-linear model and the degree-day approach using future climate change scenarios representing intermediary and high greenhouse gas emission rates. Two out of the six models assessed showed a good fit to the observed data and accurately estimated the thermal thresholds of N. elegantalis. The degree-day and the non-linear model estimated more generations in the warmer regions and fewer generations in the colder areas, but differences of up to 41% between models were recorded mainly in the warmer regions. In general, both models predicted an increase in the voltinism of N. elegantalis in most of the study area, and this increase was more pronounced in the scenarios with high emission of greenhouse gases. The mathematical model (74.8%) and the location (9.8%) were the factors that mostly contributed to the observed variation in pest voltinism. Our findings highlight the impact of climate change on the voltinism of N. elegantalis and indicate that an increase in its population growth is expected in most regions of the study area.

Heat and Cold-related Hospitalization Risk in North-East of Iran: A Time-stratified Case Crossover Design

2021 ◽  
Author(s):  
Omid Aboubakri ◽  
Hamid Reza Shoraka ◽  
Joan Ballester ◽  
Rahim Sharafkhani
Keyword(s):  
Linear Model ◽  
Hospital Admissions ◽  
Extreme Values ◽  
Crossover Design ◽  
Preventive Program ◽  
North East ◽  
Distributed Lag ◽  
Case Crossover ◽  
Non Linear ◽  
The Impact

Abstract Background: This study aimed to estimate hospitalization risk/number attributed to air extreme temperatures using time-stratified case crossover study and distributed lag non-linear model in a region of Iran during 2015-2019.Methods: A time-stratified case crossover design based on aggregated exposure data was used in this study. In order to have no overlap bias in the estimations, a fixed and disjointed window by using one-month strata was used in the design. A conditional Poisson regression model allowing for over dispersion (Quasi-Poisson) was applied into Distributed Lag Non-linear Model (DLNM). Different approaches were applied to estimate Optimum Temperature (OT). In the model, the interaction effect between temperature and humidity was assessed to see if the impact of heat or cold on Hospital Admissions (HAs) are different between different levels of humidity.Results: The cumulative effect of heat during 21 days was not significant and it was the cold that had significant cumulative adverse effect on all groups. While the number of HAs attributed to any ranges of heat, including medium, high, extreme and even all values were negligible, but a large number was attributable to cold values; about 10000 HAs were attributable to all values of cold temperature, of which about 9000 were attributed to medium range and about 1000 and less than 500 were attributed to high and extreme values of cold, respectively.Conclusion: This study highlights the need for interventions in cold seasons by policymakers. The results inform researchers as well as policy makers to address both men and women and elderly when any plan or preventive program is developed in the area under study.

scholarly journals Linear and Non-Linear Models for Remotely-Sensed Hyperspectral Image Visualization

2020 ◽  
Vol 12 (15) ◽  
pp. 2479
Author(s):  
Radu-Mihai Coliban ◽  
Maria Marincaş ◽  
Cosmin Hatfaludi ◽  
Mihai Ivanovici
Keyword(s):  
Linear Model ◽  
Linear Models ◽  
Hyperspectral Image ◽  
Point Of View ◽  
Hyperspectral Images ◽  
Image Visualization ◽  
Color Formation ◽  
Amount Of Information ◽  
Non Linear ◽  
The Impact

The visualization of hyperspectral images still constitutes an open question and may have an important impact on the consequent analysis tasks. The existing techniques fall mainly in the following categories: band selection, PCA-based approaches, linear approaches, approaches based on digital image processing techniques and machine/deep learning methods. In this article, we propose the usage of a linear model for color formation, to emulate the image acquisition process by a digital color camera. We show how the choice of spectral sensitivity curves has an impact on the visualization of hyperspectral images as RGB color images. In addition, we propose a non-linear model based on an artificial neural network. We objectively assess the impact and the intrinsic quality of the hyperspectral image visualization from the point of view of the amount of information and complexity: (i) in order to objectively quantify the amount of information present in the image, we use the color entropy as a metric; (ii) for the evaluation of the complexity of the scene we employ the color fractal dimension, as an indication of detail and texture characteristics of the image. For comparison, we use several state-of-the-art visualization techniques. We present experimental results on visualization using both the linear and non-linear color formation models, in comparison with four other methods and report on the superiority of the proposed non-linear model.

scholarly journals An Unmanned Aircraft Model for Control System Reconfiguration Analysis and Synthesis

2017 ◽  
Vol 2017 (2) ◽  
pp. 97-116
Author(s):  
Marcin Żugaj ◽  
Przemysław Bibik ◽  
Marcin Figat
Keyword(s):  
Control System ◽  
Linear Model ◽  
Dynamic Properties ◽  
Unmanned Aircraft ◽  
Control Surface ◽  
Aircraft Model ◽  
Non Linear ◽  
Analysis And Synthesis ◽  
The Impact ◽  
Control Surfaces

Abstract Reliability of unmanned aircraft is a decisive factor for conducting air tasks in a controlled airspace. One of the means of improving unmanned aircraft reliability is reconfiguration of the control system, which will allow to maintain control over the aircraft despite an occurring failure. The control system is reconfigured by using still operational control surfaces to compensate for failure consequences and to control the damaged aircraft. Development of effective reconfiguration algorithms involves utilization of a non-linear model of unmanned aircraft dynamics, in which each control surface deflection can be controlled independently. The paper describes a non-linear model of a small unmanned aircraft with decoupled control surfaces. The paper discusses aircraft flight dynamics equations and estimated equations for controllability derivatives for each control surface, the results of comparison tests of the model and actual aircraft as well as the structure of the simulation model. The developed unmanned aircraft model may be used in development and in optimization of control algorithms for aircraft with damaged control systems as well as to test the impact of failures on dynamic properties of the aircraft.

Chemoplastic Modelling for Concrete at High Temperature

2014 ◽  
Vol 5 (2) ◽  
pp. 135-146
Author(s):  
Rabah Hammoud ◽  
Rachid Boukhili ◽  
Ammar Yahia
Keyword(s):  
High Temperature ◽  
Stress State ◽  
Constitutive Law ◽  
Strength Parameter ◽  
Conventional Concrete ◽  
Normal Vectors ◽  
Stress States ◽  
Pass Through ◽  
New Formulation ◽  
The Impact

A numerical model to simulate the impact of high temperature on the behavior of conventional concrete under chemoplastic framework is developed and validated. The model is based on new formulation of a constitutive law with new chemoplastic potential. By overlaying the chemoplastic potential on the modified Etse and Willam yielding surface, both defined on the Haigh-Westergaard coordinates, it was found that the two curves do not undergo similar stress state at the same strength parameter. For an adequate evaluation of normal vectors, each surface is forced to pass through the current stress state. Keeping the loading surface unchanged, the calculation of the plastic potential need to be modified. The proposed constitutive model is validated by comparing predicted and experimental data. The model is shown to be accurate to predict different stress states of concrete under different temperature levels.

scholarly journals Bending of an annular three-layer circular plate

2019 ◽  
Vol 39 (1) ◽  
pp. 32-35
Author(s):  
Karolina Wiśniewska-Mleczko
Keyword(s):  
Mechanical Properties ◽  
Numerical Analysis ◽  
Linear Model ◽  
Circular Plate ◽  
Material Properties ◽  
Shear Stresses ◽  
The Core ◽  
Non Linear ◽  
Support Conditions ◽  
Strength And Stiffness

Abstract The main objective of this work is the numerical analysis of the strength and stiffness of an annular three-layer circular plate with variable mechanical properties of the core. The plates are subjected to bending. Numerical analysis of the deflection phenomenon is carried out under different support conditions of the plate. Furthermore, the influence of the material properties of the core (linear and non-linear model) on the shear stresses and deflecions is also investigated.

scholarly journals Drought, Climate Change, and Dryland Wheat Yield Response: An Econometric Approach

2020 ◽  
Vol 17 (14) ◽  
pp. 5264 ◽  
Author(s):  
Samira Shayanmehr ◽  
Shida Rastegari Henneberry ◽  
Mahmood Sabouhi Sabouni ◽  
Naser Shahnoushi Foroushani
Keyword(s):  
Climate Change ◽  
Linear Model ◽  
Climatic Change ◽  
Minimum Temperature ◽  
Wheat Yield ◽  
Maximum Temperature ◽  
Yield Variability ◽  
Non Linear ◽  
The Mean ◽  
The Impact

Agriculture has been identified as one of the most vulnerable sectors affected by climate change. In the present study, we investigate the impact of climatic change on dryland wheat yield in the northwest of Iran for the future time horizon of 2041–2070. The Just and Pope production function is applied to assess the impact of climate change on dryland wheat yield and yield risk for the period of 1991–2016. The Statistical Downscaling Model (SDSM) is used to generate climate parameters from General Circulation Model (GCM) outputs. The results show that minimum temperature is negatively related to average yield in the linear model while the relationship is positive in the non-linear model. An increase in precipitation increases the mean yield in either model. The maximum temperature has a positive effect on the mean yield in the linear model, while this impact is negative in the non-linear model. Drought has an adverse impact on yield levels in both models. The results also indicate that maximum temperature, precipitation, and drought are positively related to yield variability, but minimum temperature is negatively associated with yield variability. The findings also reveal that yield variability is expected to increase in response to future climate scenarios. Given these impacts of temperature on rain-fed wheat crop and its increasing vulnerability to climatic change, policy-makers should support research into and development of wheat varieties that are resistant to temperature variations.

scholarly journals Active Control Of Smart Tensegrity Structures

2014 ◽  
Vol 60 (4) ◽  
pp. 517-534 ◽  
Author(s):  
A. Al Sabouni-Zawadzka
Keyword(s):  
Stress State ◽  
Structural Health Monitoring ◽  
Active Control ◽  
Health Monitoring ◽  
Structural Control ◽  
Monitoring Systems ◽  
Tensegrity Structures ◽  
Smart Systems ◽  
Health Monitoring Systems ◽  
Stress States

AbstractThe topic of smart structures, their active control and implementation, is relatively new. Therefore, different approaches to the problem can be met. The present paper discusses variable aspects of the active control of structures. It explains the idea of smart systems, introduces different terms used in smart technique and defines the structural smartness. The author indicates differences between actively controlled structures and structural health monitoring systems and shows an example of an actively controlled smart footbridge.The analyses presented in the study concern tensegrity structures, which are prone to the structural control through self-stress state adjustment. The paper introduces examples of structural control performed on tensegrity modules and plates. An influence of several self-stress states on displacements is analyzed and a study concerning damage due to member loss is presented.

Short Stress State Questionnaire

2015 ◽  
Vol 31 (1) ◽  
pp. 20-30 ◽  
Author(s):  
William S. Helton ◽  
Katharina Näswall
Keyword(s):  
Stress State ◽  
Factor Structure ◽  
Human Performance ◽  
Self Report ◽  
Confirmatory Factor ◽  
Stress States ◽  
Related Stress ◽  
Using Data ◽  
Task Conditions ◽  
Multiple Samples

Conscious appraisals of stress, or stress states, are an important aspect of human performance. This article presents evidence supporting the validity and measurement characteristics of a short multidimensional self-report measure of stress state, the Short Stress State Questionnaire (SSSQ; Helton, 2004 ). The SSSQ measures task engagement, distress, and worry. A confirmatory factor analysis of the SSSQ using data pooled from multiple samples suggests the SSSQ does have a three factor structure and post-task changes are not due to changes in factor structure, but to mean level changes (state changes). In addition, the SSSQ demonstrates sensitivity to task stressors in line with hypotheses. Different task conditions elicited unique patterns of stress state on the three factors of the SSSQ in line with prior predictions. The 24-item SSSQ is a valid measure of stress state which may be useful to researchers interested in conscious appraisals of task-related stress.

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