Nonlinear dynamics and chaos: Their relevance to safe engineering design

As many engineering systems are neither linear nor nearly linear, they are normally modelled by nonlinear equations for which closed-form analytical solutions are unobtainable. However with the advent of powerful computers, equations can be readily integrated numerically, so that the response from a given set of starting conditions is easily established. Unlike linear systems where all initial conditions lead to one type of motion, be it to an equilibrium point or to a harmonic oscillation, nonlinear systems can exhibit chaotic transients which can setlle down to a rich and complex variety of competing steady state solutions. Associated with each steady state solution is its basin of attraction. Under the variation of a control parameter, as the attractors move and bifurcate, the basins also undergo corresponding changes and metamorphoses. Associated with the homoclinic tangling of the invariant manifolds of the saddle solution, basin boundaries can change in nature from smooth to fractal, resulting in regions of chaotic transients. The aim of the thesis is to investigate how the size and nature of the basin of attraction changes with a control parameter. We show that there can exist a rapid loss of engineering integrity accompanying the rapid erosion and stratification of the basin. We explore the engineering significance of the basin erosions that occur under increased forcing. Various measures of engineering integrity are introduced: a global measure assesses the overall basin area; a local measure assesses the distance from the attractor to the basin boundary; a velocity measure is related to the size of impulse that could be sustained without failure; and a stochastic integrity measure assesses the stability of an attractor subjected to an external noise excitation. Since engineering systems may be subjected to pulse loads of finite duration, attention is given to both the absolute and transient basins of attraction. The significant erosion of these at homoclinic tangencies is particularly highlighted in the present study, the fractal basins having a severely reduced integrity under all four criteria. We also apply the basin erosion phenomena to the problem of ship capsize. We make a numerical analysis of the steady state and transient motions of the semi-empirical nonlinear differential equations, which have been used to model the resonant rolling motions of real ships. Examinadon of the safe basin in the space of the starting conditions shows that transient capsizes can occur at a wave height that is a small fraction of that at which the final steady state motions lose their stability. It is seen that the basin is eroded quite suddenly throughout its central region by gross striations, implying that transient capsize might be a reasonably repeatable phenomenon, offering a new approach to the quantification of ship stability in waves. We conclude from this thesis that the stability of nonlinear engineering systems may, in the future, be based on the basin erosion phenomenon relating to chaotic transients and incursive fractals

Effect of Pre-Designed Instructions for Mothers of Children with Hypospadias on Reducing Postoperative Complications

Hypospadias is a common congenital anomaly with a prevalence estimated to be as high as 1 in 125 live male births. Complications after surgical procedures are possible. The incidence of complications can be reduced by meticulous preoperative planning, and judicious postoperative care. So the aim of the study was to investigate the effect of pre-designed instructions for mothers of children with hypospadias on reducing postoperative complications. A convenient sample consists of 60 mothers of children with hypospadias were included in the study. The sample was divided into 2 equal groups; the control group and the study group. Pre-post quasi experimental design was utilized to perform the aim of the study. The study was conducted in the pediatric surgical department and urology outpatient clinic at one Pediatric Hospital in Cairo. Three tools were carried out; first a questionnaire sheet (pre-post test) to assess mothers' knowledge about hypospadias, and includes also demographic data, second tool; observational checklist to evaluate mothers’ practices regarding hypospadias, third tool, postoperative complications assessment sheet, which was examined occurrence of early postoperative complications. And pre-designed instructions were provided for those mothers preoperatively. The study results revealed that a highly significant difference was present between the control and the study group regarding mothers' knowledge in post-test. The majority of mothers in the control group and the study group had inadequate level of knowledge about hypospadias in pre-test. While more than two fifth of mothers in the study group had adequate level of knowledge in post-test. The results proved that the mothers' practices in post-test were increased more than in pre-test, less than half of the mothers in pre-test were not satisfied about performing diaper care correctly, however in post-test more than three quarters of those mothers were performed this procedure correctly, and there were highly statistical significant difference between pre and post-test. Regarding early postoperative complications; the results demonstrated that more than two thirds of children in pre-test, while less than two fifth in post-test suffering from postoperative complications as; infection, urinary tract obstruction and bleeding. The difference between pre and post-test was significant. The current study concluded that the pre-designed instructions for mothers of children with hypospadias were efficient by means of marked improvement of the knowledge and practices of the study group, which support the research hypotheses. So the results indicated that children with hypospadias were fewer early postoperative complications in the study group than the control group. The study recommended that important of pre-designed instructions for mothers of children with hypospadias for reducing postoperative complications. Also highlighting additional researches about assessment of mothers' knowledge and practice in relation to care provided to their children with hypospadias. In addition to a longer follow-up is necessary to monitor the late post operative complications. Keywords: Hypospadias, children, preoperative, pre-designed instructions, postoperative complications, mothers' knowledge, practices

O panorama empresarial de Marrocos : e o ecossistema de financiamento do impacto social durante a pandemia de COVID-19

Many entrepreneurial and other collective initiatives create social impact in addition to economic gains. In this paper, we will discuss these initiatives with a focus on the financing ecosystem that is crucial to these organizations. We first discuss the social and solidarity economy before talking about entrepreneurship and social enterprises. We focus next on cooperatives, which are very important in our context for the impact they contribute to achieve. The topic of the social and solidarity economy (SSE) in Morocco garners extensive attention within economic, political, and academic circles. Given the unique Moroccan backdrop, regional advancements, demographic dynamics, and economic traits, it accentuates considerable social issues and amplifies the significance of SSE entities, especially concerning their target audience. The SSE landscape, comprising a diverse array of organizations, has continually adapted and expanded since the country gained independence to address the distinct features of its environment.Muitas iniciativas empresariais e outras iniciativas coletivas criam impacto social para além dos ganhos económicos. Neste documento, discutiremos essas iniciativas com foco no ecossistema de financiamento que é crucial para essas organizações. Começamos por discutir a economia social e solidária antes de falarmos do empreendedorismo e das empresas sociais. De seguida, focamos as cooperativas, que são muito importantes no nosso contexto pelo impacto que contribuem para alcançar. O tema da economia social e solidária (ESS) em Marrocos é objeto de grande atenção nos meios económicos, políticos e académicos. Dada a singularidade do contexto marroquino, os avanços regionais, a dinâmica demográfica e as características económicas, acentuam-se as questões sociais consideráveis e amplifica-se a importância das entidades da ESS, especialmente no que diz respeito ao seu público-alvo. O panorama da ESS, que inclui um conjunto diversificado de organizações, tem vindo a adaptar-se e a expandir-se continuamente desde a independência do país para responder às características distintas do seu ambiente. Este artigo é o resultado de uma presença prolongada no nosso campo de investigação. Recolhemos dados qualitativos após várias entrevistas que comparámos com os dados oficiais apresentados no documento. Neste artigo, fizemos um inventário das principais características do sector da ESS antes de discutirmos as medidas tomadas na sequência da pandemia de covid-19. Por fim, destacamos a necessidade de financiar as cooperativas e de incentivar a digitalização dos seus modelos de negócio

Behavioral Problems among Visually Impaired Children Studying at Special School for Blindness

Context: Visual impairment and blindness are significant ophthalmic disorders around the world. Behavioral problems in visually impaired children are considered one of the most serious health problems.Aim: The study aimed to assess behavioral problems among visually impaired children studying at a special school for blindness and assess the association between behavioral problems scores and selected demographic variables of studied children. Methods: The research design adopted for this study was a descriptive correlational design. A purposive sample was composed of one hundred and one (101) parents of children with visual impairment. The children were studying at El Nour School for blindness in Minia city. The data were collected using the parents' interview questionnaire and Child Behavior Checklist/4-18 (CBCL/4-18).Results: Withdrawn syndrome represented the highest clinical level among the studied children, followed by aggressive clinical behavior. Also, less than a fifth of them had to internalize clinical problems, and 17.8% of them had to externalize clinical problems. A highly statistically significant correlation was revealed between the score of total behavior syndromes and the age of studied children. Conclusion: Visually impaired children had problems in the total social competence score and all its subscales. About one-third of them had borderline and clinical problems regarding the total score of behavioral syndromes. Also, internalized and externalized problems had reported. The study recommended that further intervention studies are necessary, including parents' classes about behavioral problems of visually impaired children and methods to limit its effect on children's lives

Securing IP Mobility Management for Vehicular Ad Hoc Networks

The proliferation of Intelligent Transportation Systems (ITSs) applications, such as Internet access and Infotainment, highlights the requirements for improving the underlying mobility management protocols for Vehicular Ad Hoc Networks (VANETs). Mobility management protocols in VANETs are envisioned to support mobile nodes (MNs), i.e., vehicles, with seamless communications, in which service continuity is guaranteed while vehicles are roaming through different RoadSide Units (RSUs) with heterogeneous wireless technologies. Due to its standardization and widely deployment, IP mobility (also called Mobile IP (MIP)) is the most popular mobility management protocol used for mobile networks including VANETs. In addition, because of the diversity of possible applications, the Internet Engineering Task Force (IETF) issues many MIP's standardizations, such as MIPv6 and NEMO for global mobility, and Proxy MIP (PMIPv6) for localized mobility. However, many challenges have been posed for integrating IP mobility with VANETs, including the vehicle's high speeds, multi-hop communications, scalability, and ef ficiency. From a security perspective, we observe three main challenges: 1) each vehicle's anonymity and location privacy, 2) authenticating vehicles in multi-hop communications, and 3) physical-layer location privacy. In transmitting mobile IPv6 binding update signaling messages, the mobile node's Home Address (HoA) and Care-of Address (CoA) are transmitted as plain-text, hence they can be revealed by other network entities and attackers. The mobile node's HoA and CoA represent its identity and its current location, respectively, therefore revealing an MN's HoA means breaking its anonymity while revealing an MN's CoA means breaking its location privacy. On one hand, some existing anonymity and location privacy schemes require intensive computations, which means they cannot be used in such time-restricted seamless communications. On the other hand, some schemes only achieve seamless communication through low anonymity and location privacy levels. Therefore, the trade-off between the network performance, on one side, and the MN's anonymity and location privacy, on the other side, makes preservation of privacy a challenging issue. In addition, for PMIPv6 to provide IP mobility in an infrastructure-connected multi-hop VANET, an MN uses a relay node (RN) for communicating with its Mobile Access Gateway (MAG). Therefore, a mutual authentication between the MN and RN is required to thwart authentication attacks early in such scenarios. Furthermore, for a NEMO-based VANET infrastructure, which is used in public hotspots installed inside moving vehicles, protecting physical-layer location privacy is a prerequisite for achieving privacy in upper-layers such as the IP-layer. Due to the open nature of the wireless environment, a physical-layer attacker can easily localize users by employing signals transmitted from these users. In this dissertation, we address those security challenges by proposing three security schemes to be employed for different mobility management scenarios in VANETs, namely, the MIPv6, PMIPv6, and Network Mobility (NEMO) protocols. First, for MIPv6 protocol and based on the onion routing and anonymizer, we propose an anonymous and location privacy-preserving scheme (ALPP) that involves two complementary sub-schemes: anonymous home binding update (AHBU) and anonymous return routability (ARR). In addition, anonymous mutual authentication and key establishment schemes have been proposed, to authenticate a mobile node to its foreign gateway and create a shared key between them. Unlike existing schemes, ALPP alleviates the tradeoff between the networking performance and the achieved privacy level. Combining onion routing and the anonymizer in the ALPP scheme increases the achieved location privacy level, in which no entity in the network except the mobile node itself can identify this node's location. Using the entropy model, we show that ALPP achieves a higher degree of anonymity than that achieved by the mix-based scheme. Compared to existing schemes, the AHBU and ARR sub-schemes achieve smaller computation overheads and thwart both internal and external adversaries. Simulation results demonstrate that our sub-schemes have low control-packets routing delays, and are suitable for seamless communications. Second, for the multi-hop authentication problem in PMIPv6-based VANET, we propose EM3A, a novel mutual authentication scheme that guarantees the authenticity of both MN and RN. EM3A thwarts authentication attacks, including Denial of service (DoS), collusion, impersonation, replay, and man-in-the-middle attacks. EM3A works in conjunction with a proposed scheme for key establishment based on symmetric polynomials, to generate a shared secret key between an MN and an RN. This scheme achieves lower revocation overhead than that achieved by existing symmetric polynomial-based schemes. For a PMIP domain with n points of attachment and a symmetric polynomial of degree t, our scheme achieves t x 2^n-secrecy, whereas the existing symmetric polynomial-based authentication schemes achieve only t-secrecy. Computation and communication overhead analysis as well as simulation results show that EM3A achieves low authentication delay and is suitable for seamless multi-hop IP communications. Furthermore, we present a case study of a multi-hop authentication PMIP (MA-PMIP) implemented in vehicular networks. EM3A represents the multi-hop authentication in MA-PMIP to mutually authenticate the roaming vehicle and its relay vehicle. Compared to other authentication schemes, we show that our MA-PMIP protocol with EM3A achieves 99.6% and 96.8% reductions in authentication delay and communication overhead, respectively. Finally, we consider the physical-layer location privacy attacks in the NEMO-based VANETs scenario, such as would be presented by a public hotspot installed inside a moving vehicle. We modify the obfuscation, i.e., concealment, and power variability ideas and propose a new physical-layer location privacy scheme, the fake point-cluster based scheme, to prevent attackers from localizing users inside NEMO-based VANET hotspots. Involving the fake point and cluster based sub-schemes, the proposed scheme can: 1) confuse the attackers by increasing the estimation errors of their Received Signal Strength (RSSs) measurements, and 2) prevent attackers' monitoring devices from detecting the user's transmitted signals. We show that our scheme not only achieves higher location privacy, but also increases the overall network performance. Employing correctness, accuracy, and certainty as three different metrics, we analytically measure the location privacy achieved by our proposed scheme. In addition, using extensive simulations, we demonstrate that the fake point-cluster based scheme can be practically implemented in high-speed VANETs' scenarios

Quantitative trait loci (QTL) analysis of flag leaf senescence in wheat (Triticum aestivum L.) with microsatellite DNA markers under water-stressed condition

The objective of this study was to detect quantitative trait loci (QTL) associated with drought tolerance in wheat genotypes by simple sequence repeat (SSR) markers and to provide valuable information for marker assisted selection. SSR markers linked to flag leaf senescence (FLS) was identified in two DNA pools, which were established using F2 mapping population, resulting from a cross between a drought sensitive genotype 'Variant-11' and drought tolerant genotype 'Veery'. Parents were screened initially with 34 SSR primer pairs. The linkage map was constructed with the six linked markers into one linkage group covering 82.7 cm. QTL detection with analysis of variance showed that all of the six markers were significantly associated with drought tolerance in this population. Single marker regression (SMR) analysis revealed that R-square percentage ranged from 39.3% (Xgwm339) and 12.3% (Xgwm577). Simple interval mapping (SIM) located a QTL for leaf flag senescence, between markers interval Xgwm566 and Xgwm339, while composite interval mapping (CIM) indicated a QTL location between the interval marker Xgwm296 and Xgwm566. The SSR markers can be used for the detection of QTLs quantitative trait loci linked with flag leaf senescence as indicator for drought tolerance.Key words: Flag leaf senescence, Triticum aestivum L., SSR markers, simple interval mapping (SIM), composite interval mapping (CIM), quantitative trait loci (QTL)

La gouvernance systémique du sport de haut niveau au Maroc Structuration inter-organisationnelle

Etudier la gouvernance systémique du sport de haut niveau (SHN) au Maroc, revient à analyser la structuration d’un système régulé par trois acteurs majeurs : ministère chargé du sport (MS), comité national olympique (CNOM), fédérations royales sportives (FRSM). En considérant ces dernières comme unité centrale, il s’agit d’aborder la relation entre celles ci et les autres acteurs, au regard des principales théories de la gouvernance. En adoptant une démarche qualitative, des entretiens ont été réalisés avec 53 acteurs sportifs susceptibles de par leurs statuts de fournir des réponses satisfaisantes quant à l’objet étudié. L’analyse des données recueillies montre que la relation MS/FRSM est structurée autour des notions : « contrat d’objectifs » et « acteurs relais ». Mais ce contrat ne représente qu’une formalité administrative que les FRSM doivent signer pour bénéficier de la subvention ministérielle. Ce qui représente le reflet d’une vision disciplinaire de la gouvernance. Quant aux « acteurs relais », ils sont à l’origine de la création d’un système d’action reliant fonctionnaires du MS aux dirigeants fédéraux, fondé sur l’absence d’une rationalité instrumentale objective. Les résultats montrent aussi que la relation CNOM/FRSM est ponctuelle, et s’articule autour d’une convention dont les termes s’inscrivent dans une logique financière, caractéristique d’une rationalité disciplinaire de la gouvernance