Generation of planar tensegrity structures through cellular multiplication

Tensegrity structures are frameworks in a stable self-equilibrated prestress state that have been applied in various fields in science and engineering. Research into tensegrity structures has resulted in reliable techniques for their form finding and analysis. However, most techniques address topology and form separately. This paper presents a bio-inspired approach for the combined topology identification and form finding of planar tensegrity structures. Tensegrity structures are generated using tensegrity cells (elementary stable self-stressed units that have been proven to compose any tensegrity structure) according to two multiplication mechanisms: cellular adhesion and fusion. Changes in the dimension of the self-stress space of the structure are found to depend on the number of adhesion and fusion steps conducted as well as on the interaction among the cells composing the system. A methodology for defining a basis of the self-stress space is also provided. Through the definition of the equilibrium shape, the number of nodes and members as well as the number of self-stress states, the cellular multiplication method can integrate design considerations, providing great flexibility and control over the tensegrity structure designed and opening the door to the development of a whole new realm of planar tensegrity systems with controllable characteristics.Comment: 29 pages, 19 figures, to appear at Applied Mathematical Modelin

Cellular morphogenesis of three-dimensional tensegrity structures

The topology and form finding of tensegrity structures have been studied extensively since the introduction of the tensegrity concept. However, most of these studies address topology and form separately, where the former represented a research focus of rigidity theory and graph theory, while the latter attracted the attention of structural engineers. In this paper, a biomimetic approach for the combined topology and form finding of spatial tensegrity systems is introduced. Tensegrity cells, elementary infinitesimally rigid self-stressed structures that have been proven to compose any tensegrity, are used to generate more complex tensegrity structures through the morphogenesis mechanisms of adhesion and fusion. A methodology for constructing a basis to describe the self-stress space is also provided. Through the definition of self-stress, the cellular morphogenesis method can integrate design considerations, such as a desired shape or number of nodes and members, providing great flexibility and control over the tensegrity structure generated.Comment: 31 pages, 17 figure

Analysis of self-equilibrated networks through cellular modeling

Network equilibrium models represent a versatile tool for the analysis of interconnected objects and their relationships. They have been widely employed in both science and engineering to study the behavior of complex systems under various conditions, including external perturbations and damage. In this paper, network equilibrium models are revisited through graph-theory laws and attributes with special focus on systems that can sustain equilibrium in the absence of external perturbations (self-equilibrium). A new approach for the analysis of self-equilibrated networks is proposed; they are modeled as a collection of cells, predefined elementary network units that have been mathematically shown to compose any self-equilibrated network. Consequently, the equilibrium state of complex self-equilibrated systems can be obtained through the study of individual cell equilibria and their interactions. A series of examples that highlight the flexibility of network equilibrium models are included in the paper. The examples attest how the proposed approach, which combines topological as well as geometrical considerations, can be used to decipher the state of complex systems.Comment: 38 pages, 23 figure

Determinants of structural change in Africa

Cet article examine la contribution de la transformation structurelle à l’accroissement de la productivité du travail en Afrique ainsi que ses déterminants. L’analyse porte sur les données de la période 1991-2017 couvrant 37 pays du continent.  La croissance de la productivité du travail a été globalement faible (+1,0% par an) au cours de la période d’analyse. La contribution de la transformation structurelle a représenté environ 1/3 des gains de productivité. Elle s’est nettement améliorée depuis le début des années 2000, même si la part intra sectorielle reste prépondérante. Dans les pays sans littoral, la contribution de la transformation structurelle à l’accroissement de la productivité est restée positive et supérieure à son niveau dans les pays côtiers. La réallocation de la main-d’œuvre vers le secteur des services a été le principal moteur de la transformation structurelle sur le continent au cours de la période 1991-2017. En Afrique de l’Est, une phase intermédiaire est observée durant la période 1991-2001. Cette dernière est marquée notamment par une transformation structurelle portée par le secteur industriel. Enfin, l’analyse économétrique sur les potentiels déterminants révèle que le rythme de la transformation structurelle est fortement influencé par le capital humain et physique, la croissance démographique et le niveau initial de l’emploi agricole. La combinaison d’effets push et pull est ainsi nécessaire pour une accélération de la transformation structurelle sur le continent et l’accroissement du revenu par habitant. D’une part les investissements dans les infrastructures économiques seront cruciaux pour accélérer la croissance dans les secteurs non agricoles, créatrice d’emploi. D’autre part l’accélération de la transition démographique et l’investissement dans le capital humain contribueraient à réduire la pression sur l’offre de travail tout en garantissant une main d’œuvre qualifiée.  Compte tenu de sa part initiale dans l’économie globale, une croissance rapide du secteur agricole sera également nécessaire pour une accélération du processus de transformation structurelle. Mots-Clés: croissance et développement, transformation structurelle, productivité du travail, ouverture commerciale, AfriqueThis paper examines the contribution of structural change to increasing labor productivity in Africa and its determinants. The analysis covers data from the period 1991-2017 covering 37 countries on the continent. Labor productivity growth was globally low (+ 1.0% per year) during the analysis period. The contribution of structural change represented around one third (1/3) of productivity gains. It has improved significantly since the early 2000s, even if the within-sector productivity share remains preponderant. In landlocked countries, the contribution of structural change to productivity growth has remained positive and above its level in coastal countries. The reallocation of labor to the service sector was the main driver of structural change in Africa during the period 1991-2017. In East Africa, an intermediate phase was observed during the period 1991-2001. The latter is characterized in particular by a structural change driven by the industrial sector. Finally, the econometric analysis of the determinant reveals that the pace of structural change is strongly influenced by human and physical capital, population growth and the initial level of agricultural employment. The combination of push and pull effects is therefore necessary for accelerating structural transformation on the continent and increasing per capita income. On the one hand, investments in economic infrastructure will be crucial to accelerate growth in the non-agricultural, job-creating sectors. On the other hand, the acceleration of the demographic transition and investment in human capital would help to reduce the pressure on the labor supply while guaranteeing a skilled workforce. Given its initial share in the global economy, rapid growth in the agricultural sector will also be necessary to accelerate the process of structural change. Keywords: growth and development, structural change, labor productivity, trade, Afric

Agricultural land market and structural change in Morocco: A dynamic computable general equilibrium analysis

Le présent article analyse l’impact d’une administration du prix du foncier sur la transformation structurelle, de l’agriculture vers les autres secteurs de l’économie. Nous avons développé un modèle d’équilibre général  calculable dynamique séquentiel à deux secteurs, dans lequel le secteur agricole rural utilise le facteur terre, en plus du facteur travail et du capital. Le secteur non agricole urbain, utilise la main d’œuvre et du capital. La mobilité de la main d’œuvre de l’agriculture vers le secteur urbain non agricole est favorisée par la migration. Le modèle est calibré sur la matrice de comptabilité sociale de 2013 du Maroc, construit à cet effet. Les résultats empiriques montrent que l’administration des prix du foncier a un impact négatif sur la demande de travail dans le secteur non agricole, entraine un retard de la transformation structurelle et a un effet positif et significatif sur les taux de salaires ruraux. Mots-Clés : Transformation structurelle, foncier, modèle d’équilibre général calculable, MarocThis paper analyzes the impact of a land price administration on structural change from agricultural sector to other sectors of the economy. We developed a two-sector recursive dynamic computable general equilibrium model, in which the rural agricultural sector uses the land factor, in addition to labor and capital. The urban non-farm sector uses labor and capital. The mobility of the labor force from agriculture to the non-agricultural urban sector is favored by migration. The model is calibrated on the 2013 social accounting matrix of Morocco, built for this purpose. The empirical results show that the administration of land prices has a negative impact on labor demand in the non-agricultural sector, leads to a delay in structural transformation and has a positive and significant effect on rural wages. Keywords: structural transformation, land, computable general equilibrium model, Morocc

On the boundedness of solutions of some fuzzy dynamical control systems

The asymptotic behavior of solutions of fuzzy control systems is a component of the study of fuzzy control theory. The study of stability for T-S (Takagi-Sugeno) fuzzy systems, which process qualitative data through linguistic expressions, is the subject of this paper. Asymptotic stability is conservative in many real-world applications due to measurement noise and other disruptions. The ultimate limit, which indicates that the mistakes stay in a specific area close to the origin after a long enough amount of time, is a crucial characteristic that is frequently defined for such systems. We are interested with the problem of the state feedback controller for T-S fuzzy models with uncertainties where the global exponential ultimate boundedness of solutions is studied for certain fuzzy control systems. We use common quadratic Lyapunov function and parallel distributed compensation controller techniques to study the asymptotic behavior of the solutions of fuzzy control system in presence of perturbations. An example demonstrating the validity of the main result is discussed

A sophisticated Drowsiness Detection System via Deep Transfer Learning for real time scenarios

Driver drowsiness is one of the leading causes of road accidents resulting in serious physical injuries, fatalities, and substantial economic losses. A sophisticated Driver Drowsiness Detection (DDD) system can alert the driver in case of abnormal behavior and avoid catastrophes. Several studies have already addressed driver drowsiness through behavioral measures and facial features. In this paper, we propose a hybrid real-time DDD system based on the Eyes Closure Ratio and Mouth Opening Ratio using simple camera and deep learning techniques. This system seeks to model the driver's behavior in order to alert him/her in case of drowsiness states to avoid potential accidents. The main contribution of the proposed approach is to build a reliable system able to avoid false detected drowsiness situations and to alert only the real ones. To this end, our research procedure is divided into two processes. The offline process performs a classification module using pretrained Convolutional Neural Networks (CNNs) to detect the drowsiness of the driver. In the online process, we calculate the percentage of the eyes' closure and yawning frequency of the driver online from real-time video using the Chebyshev distance instead of the classic Euclidean distance. The accurate drowsiness state of the driver is evaluated with the aid of the pretrained CNNs based on an ensemble learning paradigm. In order to improve models' performances, we applied data augmentation techniques for the generated dataset. The accuracies achieved are 97 % for the VGG16 model, 96% for VGG19 model and 98% for ResNet50 model. This system can assess the driver's dynamics with a precision rate of 98%

Fuzzy logic-based vehicle safety estimation using V2V communications and on-board embedded ROS-based architecture for safe traffic management system in hail city

Estimating the state of surrounding vehicles is crucial to either prevent or avoid collisions with other road users. However, due to insufficient historical data and the unpredictability of future driving tactics, estimating the safety status is a difficult undertaking. To address this problem, an intelligent and autonomous traffic management system based on V2V technology is proposed. The main contribution of this work is to design a new system that uses a real-time control system and a fuzzy logic algorithm to estimate safety. The robot operating system (ROS) is the foundation of the control architechture, which connects all the various system nodes and generates the decision in the form of a speech and graphical message. The safe path is determined by a safety evaluation system that combines sensor data with a fuzzy classifier. Moreover, the suitable information processed by each vehicle unit is shared in the group to avoid unexpected problems related to speed, sudden braking, unplanned deviation, street holes, road bumps, and any kind of street issues. The connection is provided through a network based on the ZigBee protocol. The results of vehicle tests show that the proposed method provides a more reliable estimate of safety as compared to other methods

Scenarios for the Agricultural Sector in South and East Mediterranean Countries by 2030

The paper builds predictive scenarios for the agricultural sector of eleven Mediterranean countries (Med 11), namely Algeria, Egypt, Israel, Jordan, Lebanon, Libya, Morocco, Palestine, Syria, Tunisia and Turkey. First, it assesses the performance trends of the Med 11 agricultural sector with a focus on production, consumption and trade patterns, incentives, trade protection policies and trade relations with the EU and productivity dynamics and their determinants. Secondly, it presents four scenarios based on the main value chains of the agriculture sector of Med 11: animal products, fruits and vegetables, sugar and edible oil, cereals and fish and other sea products. The four scenarios are: business as usual, Mediterranean One global Player, the Euro Mediterranean Area under threat and the EU and Med 11 as Regional Player

Rare variants in ANO1, encoding a calcium-activated chloride channel, predispose to moyamoya disease

Moyamoya disease, a cerebrovascular disease leading to strokes in children and young adults, is characterized by progressive occlusion of the distal internal carotid arteries and the formation of collateral vessels. Altered genes play a prominent role in the aetiology of moyamoya disease, but a causative gene is not identified in the majority of cases. Exome sequencing data from 151 individuals from 84 unsolved families were analysed to identify further genes for moyamoya disease, then candidate genes assessed in additional cases (150 probands). Two families had the same rare variant in ANO1, which encodes a calcium-activated chloride channel, anoctamin-1. Haplotype analyses found the families were related, and ANO1 p.Met658Val segregated with moyamoya disease in the family with an LOD score of 3.3. Six additional ANO1 rare variants were identified in moyamoya disease families. The ANO1 rare variants were assessed using patch-clamp recordings, and the majority of variants, including ANO1 p.Met658Val, displayed increased sensitivity to intracellular Ca2+. Patients harbouring these gain-of-function ANO1 variants had classic features of moyamoya disease, but also had aneurysm, stenosis and/or occlusion in the posterior circulation. Our studies support that ANO1 gain-of-function pathogenic variants predispose to moyamoya disease and are associated with unique involvement of the posterior circulation