L'objectif principal de cette étude est de développer des outils de simulation numérique pour évaluer la vulnérabilité des constructions en maçonnerie sous chargements variés. Ainsi, le comportement de la maçonnerie non armée sous chargement monotone en macro- et micro-échelles est étudié. La simulation du comportement non linéaire du mur de maçonnerie avant et après le pic et la capture de son mécanisme de rupture sont les points centraux de ce travail. Tout d'abord, le mur de maçonnerie d'un panneau est remplacé par deux barres simples utilisant la stratégie des macros-éléments et un comportement tri-linéaire est proposé pour évaluer la résistance à la rupture de la paroi ainsi que son comportement avant et après le pic. L'absence de l'information sur le mécanisme de rupture du mur de maçonnerie et la relation entre le mécanisme de rupture et les propriétés mécaniques des éléments barres dans ce type de modélisation conduisent à opter pour une autre description de ces structures à savoir la stratégie de micro-modélisation. Dans cette stratégie, les unités et les mortiers sont modélisés séparément et l'ensemble du comportement inélastique du mur de maçonnerie est supposé se produire dans les mortiers. Par conséquent, une attention particulière sera accordée au développement d'une description fiable des propriétés matérielles de ces éléments à l'aide d'une loi constitutive précise. La représentation tridimensionnelle d'un mur de maçonnerie faite dans ce travail, améliore la capacité des méthodes actuelles pour prédire le comportement de la maçonnerie sous les deux chargements en plan et hors du plan. D'abord, des enveloppes de rupture comprenant la tension limite et la surface de charge de Mohr-Coulomb sont assignées à l'élément d'interface du code éléments finis GEFDyn. Ensuite, la loi de comportement est améliorée en ajoutant un seuil de compression aux surfaces de charge pour inclure l'endommagement en compression de la maçonnerie à travers l'élément d'interface. Dans le nouveau modèle élastoplastique, les écrouissages négatifs des seuils de traction et de compression ainsi que la cohésion du mortier sont pris en considération. La capacité des deux modèles pour reproduire le comportement avant et après le pic de la résistance au cisaillement du mur de maçonnerie est vérifiée en comparant les résultats numériques avec les données expérimentales. L'importance de l'interaction entre les seuils de compression et celui du cisaillement est montrée en comparant les résultats obtenus avec ceux d'un test réel. Les résultats ont révélé que le second modèle est capable de simuler le comportement du mur de maçonnerie avec une bonne précision. Ensuite, l'effet des propriétés géométriques de la paroi telles que l'existence d'une ouverture et l'élancement, les propriétés des mortiers comme la cohésion, la résistance en traction et la résistance en compression ainsi que la contrainte verticale initiale dans le mur, sur la résistance latérale et le mécanisme de rupture des murs de maçonnerie est démontré. En outre, afin de présenter l'état d'endommagement, des indices de dommage, portant sur la longueur totale des fissures dans différentes rangées et colonnes de mortiers sont introduits et comparés pour différentes configurations. Les longueurs de glissement et d'ouverture de fissures dans les mortiers horizontale et verticale respectivement, sont les paramètres les plus importants qui contrôlent le comportement du mur. Enfin, la relation entre les profils de fissuration différents et les propriétés des matériaux y contribuant sont résumées dans un tableau.

There exists considerable debate in the texture community about whether grain interactions are a necessary factor to explain the development of deformation textures in polycrystalline metals. Computer simulations indicate that grain interactions play a significant role, while experimental evidence shows that the material type and starting orientation are more important in the development of texture and microstructure. A balanced review of the literature on face-centered cubic metals shows that the opposing viewpoints have developed due to the lack of any complete experimental study which considers both the intrinsic (material type and starting orientation) and extrinsic (grain interaction) factors. In this study, a novel method was developed to assemble ideally orientated crystalline aggregates in 99.99\% aluminum (Al) or copper (Cu) to experimentally evaluate the effect of grain interactions on room temperature deformation texture. Ideal orientations relevant to face-centered cubic rolling textures, Cube $\{100\}\left<001\right>$, Goss $\{110\}\left<001\right>$, Brass $\{110\}\left<1\bar{1}2\right>$ and Copper $\{112\}\left<11\bar{1}\right>$ were paired in different combinations and deformed by plane strain compression to moderate strain levels of 1.0 to 1.5. Orientation dependent mechanical behavior was distinguishable from that of the neighbor-influenced behavior. In interacting crystals the constraint on the rolling direction shear strains ($\gamma_{_{XY}}, \gamma_{_{XZ}}$) was found to be most critical to show the effect of interactions via the evolution of local microstructure and microtexture. Interacting crystals with increasing deformations were observed to gradually rotate towards the S-component, $\{123\}\langle\bar{6}\bar{3}4\rangle$. Apart from the average lattice reorientations, the interacting crystals also developed strong long-range orientation gradients inside the bulk of the crystal, which were identified as accumulating misorientations across the deformation boundaries. Based on a statistical procedure using quaternions, the orientation and interaction related heterogeneous deformations were characterized by three principal component vectors and their respective eigenvalues for both the orientation and misorientation distributions. For the case of a medium stacking fault energy metal like Cu, the texture and microstructure development depends wholly on the starting orientations. Microstructural instabilities in Cu are explained through a local slip clustering process, and the possible role of grain interactions on such instabilities is proposed. In contrast, the texture and microstructure development in a high stacking fault energy metal like Al is found to be dependent on the grain interactions. In general, orientation, grain interaction and material type were found to be key factors in the development of rolling textures in face-centered cubic metals and alloys. Moreso, in the texture development not any single parameter can be held responsible, rather, the interdependency of each of the three parameters must be considered. In this frame-work polycrystalline grains can be classified into four types according to their stability and susceptibility during deformation. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2009-09-25 23:59:11.809

Masonry walls subjected to out-of-plane loading, such as in a seismic event, require reinforcement to improve the ductility of the system. In current masonry construction practice, reinforcement is placed internally and fully grouted. For new construction this can make the wall unjustifiably heavy by not taking advantage of its light, hollow structure. For existing construction, it is difficult to retrofit using this technique. Additionally, the reinforcement is located close to the neutral axis which reduces its effectiveness. Fiber-Reinforced Polymer (FRP) bars, strips and sheets are becoming increasingly popular in construction applications due to their noncorrosive nature and ease of installation. Also, stainless steel bars are used where the structure is exposed to a corrosive environment but have not found wider application for masonry structures. This study is an experimental investigation of the structural performance of masonry walls reinforced with Near-Surface-Mounted (NSM) FRP and stainless steel reinforcement under out-of-plane bending. Additionally, walls with Externally Bonded (EB) FRP sheets were tested. The study simulates retrofitting applications and also proposes the NSM technique for new wall construction, using pre-grooved blocks, in lieu of the conventional method of internal reinforcing and grouting. To accommodate the NSM reinforcement, the grooves in the masonry blocks were aligned with ducts used to anchor the NSM reinforcement in the concrete footing. Seven wall specimens were tested, including walls reinforced with conventional and stainless steel bars, glass-fibre reinforced polymer (GFRP), and carbon-FRP (CFRP) reinforcement. The study demonstrated the feasibility and effectiveness of the NSM technique for new construction. Walls with NSM reinforcement showed a superior performance to those with EB reinforcement. It was shown that increasing the FRP reinforcement ratio may result in a change of failure mode, and as such, the increase in strength may not be proportional to the increase in reinforcement ratio. NSM steel-reinforced walls showed a superior performance in terms of strength, stiffness and the ductility associated with the formation of a plastic hinge at the base. / Thesis (Master, Civil Engineering) -- Queen's University, 2010-05-31 06:24:20.976

No description available.

Many tasks in Natural Language Processing (NLP) require us to predict a relational structure over entities. For example, in Semantic Role Labelling we try to predict the ’semantic role’ relation between a predicate verb and its argument constituents. Often NLP tasks not only involve related entities but also relations that are stochastically correlated. For instance, in Semantic Role Labelling the roles of different constituents are correlated: we cannot assign the agent role to one constituent if we have already assigned this role to another. Statistical Relational Learning (also known as First Order Probabilistic Logic) allows us to capture the aforementioned nature of NLP tasks because it is based on the notions of entities, relations and stochastic correlations between relationships. It is therefore often straightforward to formulate an NLP task using a First Order probabilistic language such as Markov Logic. However, the generality of this approach comes at a price: the process of finding the relational structure with highest probability, also known as maximum a posteriori (MAP) inference, is often inefficient, if not intractable. In this work we seek to improve the efficiency of MAP inference for Statistical Relational Learning. We propose a meta-algorithm, namely Cutting Plane Inference (CPI), that iteratively solves small subproblems of the original problem using any existing MAP technique and inspects parts of the problem that are not yet included in the current subproblem but could potentially lead to an improved solution. Our hypothesis is that this algorithm can dramatically improve the efficiency of existing methods while remaining at least as accurate. We frame the algorithm in Markov Logic, a language that combines First Order Logic and Markov Networks. Our hypothesis is evaluated using two tasks: Semantic Role Labelling and Entity Resolution. It is shown that the proposed algorithm improves the efficiency of two existing methods by two orders of magnitude and leads an approximate method to more probable solutions. We also give show that CPI, at convergence, is guaranteed to be at least as accurate as the method used within its inner loop. Another core contribution of this work is a theoretic and empirical analysis of the boundary conditions of Cutting Plane Inference. We describe cases when Cutting Plane Inference will definitely be difficult (because it instantiates large networks or needs many iterations) and when it will be easy (because it instantiates small networks and needs only few iterations).

Fatigue, or failure of material due to repeated cyclic loading, is one of the most common causes of mechanical failures. The risk of fatigue in a load carrying component is often lowered by adding material, thereby reducing stresses. This increases the component weight, reducing the performance of the component and increasing its manufacturing cost. There is thus a need to design components to be as light as possible, while keeping the risk of fatigue at a low enough level, i.e. there is a need for optimization of the component subject to fatigue constraints.  This thesis deals with design against fatigue using topology optimization, which is a form of structural optimization where an optimal design is sought by using mathematical programming to decide which parts of a design domain should be filled with material, and which should not.  To predict fatigue, accurate representation of the geometry and accurate stress computation are of utmost importance. In this thesis, methods for imposing constraints such as minimum inner radii and minimum member sizes in the form of four new density filters are proposed. The filters are able to generate a very sharp representation of the structural boundary. A method for improving the accuracy of stress results at the structural boundary is also proposed, based on extrapolation of results from the interior of the structure. The method gives more accurate stresses, which affects the resulting structures when solving optimization problems.  A formulation for fatigue constraints in topology optimization is proposed, based on the weakest link integral. The formulation avoids the problem of choosing between accurate but costly local constraints, and efficient but approximate aggregated constraints, and gives a theoretical motivation for using expressions similar to the p-norm of stresses.  For verifying calculations of the fatigue probability of an optimized structure, critical plane criteria are commonly used. A new method for evaluating such criteria using optimization methods is proposed, and is proved to give results within a user given error tolerance. It is shown that compared to existing brute force methods, the proposed method evaluates significantly fewer planes in the search of the critical one. / <p>QC 20150504</p>

Increased BCS at calving due to nutritional manipulation during the prepartum period resulted in greater mobilization of body fat after calving, regardless of plane of nutrition during the last 60 d of gestation. Although fatter cows were shown to have greater mobilization of reserves during the postpartum period, they maintained greater BCS at all points from calving to weaning compared to cows calving with fewer reserves at calving. A unique finding of this experiment was that the variation in BCS at calving was positively associated with BCS loss for cows fed to accrete BC during the prepartum period but was not associated with BCS loss for cows fed at maintenance levels during gestation. This finding suggests a threshold response in which BCS loss postpartum is only related to BCS at calving of 6.5 or greater. Progeny of fatter cows were heavier at d 40 and 84, but no treatment differences existed at weaning. The relationship between BCS at calving and calf BW at d 40 differed by treatment. This suggests a threshold response in which calf BW is positively related to increases in BCS up to 5.75. At BCS ≥ 5.75 calf weights were greater than at lower BCS levels but were unrelated to incremental changes in BCS. Altering dietary energy level during mid and late gestation altered the net lipolytic rate of beef cows and altered the timing of changes in tissue sensitivity and total lipolysis. Basal release of NEFA did not change for cows on a maintenance diet, but increased significantly for fatter cows prior to calving, whereas basal glycerol was unaffected by treatment. The stimulated release of glycerol was also unaffected by treatment, but increased across all periods. The ratio of stimulated glycerol and NEFA release to basal release of glycerol and NEFA indicate that the AT of HI cows has a delayed response to the increase in sensitivity to lipolytic stimulants that is associated with homeorhetic adaptations; however, at 7 d after calving, no differences were observed for net or total lipolytic capacity of the tissue. Providing mature beef cows ad libitum access to a high‐energy diet alters pre‐calving sensitivity of AT, but after calving and when animals are receiving a common diet, no differences in lipolysis were observed. Thus, BCS (4.91 to 6.56), as manipulated by diet, does not appear to impair lipolytic function and regulation in beef cows as observed in dairy cows.

The paper describes major features of an unmanned aerial vehicle, designed undersafety and performance requirements for missions of aerial photography and remotesensing in precision agriculture. Unmanned aerial vehicles have vast potential asobservation and data gathering platforms for a wide variety of applications. The goalof the project was to develop a small, low cost, electrically powered, unmanned aerialvehicle designed in conjunction with a payload of imaging equipment to obtainremote sensing images of agricultural fields. The results indicate that this conceptwas feasible in obtaining high quality aerial images.

No description available.

The purpose of this study was to develop a course of study on Plane Geometry for the 8th grade, based upon the Instructional Systems Analysis technique. The systems model used was that developed by Bartel.The entire study involved identifying, selecting, and sequencing learning tasks. An elaborate review of resource materials on Plane Geometry yielded one hundred and fifty-five related tasks.The instrument developed to gather pertinent data had two parts to it. Part one contained seventeen items relating to the personal profile of the respondent. Part two consisted of the one hundred and fifty-five identified, verified, and correctly stated manipulative tasks. The tasks were grouped into two broad divisions. Each respondent rated each task on a 3-point scale according to the level of instructional importance he/she judged the task(s) should receive. A rating of 3 represented the highest level of importance; 2, average; and 1, least.The survey utilized the services of sixty-eight Nigerians currently on the Technical Teachers Training Program (TTTP) in the U.S. Information regarding the institutions and population of Nigerians on the program was obtained from the Training and Development Program (TDP) office in Washington, D.C. From the list of thirty-two possible institutions, twelve institutions met the criterion for participation.A Five-Interval Sampling Technique (FIST) was used to select subjects from the participating institutions. This gave the researcher a possible seventy subjects. Each subject's participation was purely voluntary. Thus the 73.6 percent return was considered satisfactory.The interpretation of data involved two analyses. Analysis one dealt with biographical information on each participant. The second analysis computed the summary of task ratings on the one hundred and fifty-five instrument items.Selection of tasks for inclusion in the course of study reported in this study was based on the judgments of the subjects. Higher mean values were used as the basis for selection. Overall, thirty top tasks were selected and sequenced for the purpose of the course of study under investigation.