To see the other types of publications on this topic, follow the link: The UAV placement problem.
Dissertations / Theses on the topic 'The UAV placement problem'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'The UAV placement problem.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Ait, Saadi Amylia. "Coordination of scout drones (UAVs) in smart-city to serve autonomous vehicles." Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASG064.
Full textAbstract:
Le sujet des véhicules aériens sans pilote (VAP) est devenu un domaine d'étude prometteurtant dans la recherche que dans l'industrie. En raison de leur autonomie et de leur efficacitéen vol, les drones sont considérablement utilisés dans diverses applications pour différentestâches. Actuellement, l'autonomie du drone est un problème difficile qui peut avoir un impactà la fois sur ses performances et sur sa sécurité pendant la mission. Pendant le vol, les dronesautonomes sont tenus d'investiguer la zone et de déterminer efficacement leur trajectoire enpréservant leurs ressources (énergie liée à la fois à l'altitude et à la longueur de la trajectoire) et en satisfaisant certaines contraintes (obstacles et rotations d'axe). Ce problème estdéfini comme le problème de planification de trajectoire UAV qui nécessite des algorithmesefficaces pour être résolus, souvent des algorithmes d'intelligence artificielle. Dans cettethèse, nous présentons deux nouvelles approches pour résoudre le problème de planificationde trajectoire UAV. La première approche est un algorithme amélioré basé sur l'algorithmed'optimisation des vautours africains, appelé algorithmes CCO-AVOA, qui intègre la cartechaotique, la mutation de Cauchy et les stratégies d'apprentissage basées sur l'oppositiond'élite. Ces trois stratégies améliorent les performances de l'algorithme AVOA original entermes de diversité des solutions et d'équilibre de recherche exploration/exploitation. Unedeuxième approche est une approche hybride, appelée CAOSA, basée sur l'hybridation deChaotic Aquila Optimization avec des algorithmes de recuit simulé. L'introduction de lacarte chaotique améliore la diversité de l'optimisation Aquila (AO), tandis que l'algorithmede recuit simulé (SA) est appliqué comme algorithme de recherche locale pour améliorer larecherche d'exploitation de l'algorithme AO traditionnel. Enfin, l'autonomie et l'efficacitédu drone sont abordées dans une autre application importante, qui est le problème de placement du drone. La question du placement de l'UAV repose sur la recherche de l'emplacementoptimal du drone qui satisfait à la fois la couverture du réseau et la connectivité tout entenant compte de la limitation de l'UAV en termes d'énergie et de charge. Dans ce contexte, nous avons proposé un hybride efficace appelé IMRFO-TS, basé sur la combinaisonde l'amélioration de l'optimisation de la recherche de nourriture des raies manta, qui intègreune stratégie de contrôle tangentiel et d'algorithme de recherche taboueThe subject of Unmanned Aerial Vehicles (UAVs) has become a promising study field in bothresearch and industry. Due to their autonomy and efficiency in flight, UAVs are considerablyused in various applications for different tasks. Actually, the autonomy of the UAVis a challenging issue that can impact both its performance and safety during the mission.During the flight, the autonomous UAVs are required to investigate the area and determineefficiently their trajectory by preserving their resources (energy related to both altitude andpath length) and satisfying some constraints (obstacles and axe rotations). This problem isdefined as the UAV path planning problem that requires efficient algorithms to be solved,often Artificial Intelligence algorithms. In this thesis, we present two novel approachesfor solving the UAV path planning problem. The first approach is an improved algorithmbased on African Vultures Optimization Algorithm (AVOA), called CCO-AVOA algorithms,which integrates the Chaotic map, Cauchy mutation, and Elite Opposition-based learningstrategies. These three strategies improve the performance of the original AVOA algorithmin terms of the diversity of solutions and the exploration/exploitation search balance. Asecond approach is a hybrid-based approach, called CAOSA, based on the hybridization ofChaotic Aquila Optimization with Simulated Annealing algorithms. The introduction of thechaotic map enhances the diversity of the Aquila Optimization (AO), while the SimulatedAnnealing (SA) algorithm is applied as a local search algorithm to improve the exploitationsearch of the traditional AO algorithm. Finally, the autonomy and efficiency of the UAVare tackled in another important application, which is the UAV placement problem. Theissue of the UAV placement relays on finding the optimal UAV placement that satisfies boththe network coverage and connectivity while considering the UAV's limitation from energyand load. In this context, we proposed an efficient hybrid called IMRFO-TS, based on thecombination of Improved Manta Ray Foraging Optimization, which integrates a tangentialcontrol strategy and Tabu Search algorithms
2
Stilson, Mona T. "Multi-UAV Control: An Envisioned World Design Problem." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1245640561.
Full text
3
Baker, Chris. "A combined mechanism for UAV explorative path planning, task allocation and predictive placement." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/405212/.
Full textAbstract:
The use of Unmanned Aerial Vehicles (UAVs) is becoming ever more common by people or organisations who wish to get information about an area quickly and without a human presence. As a result, there has been a concerted effort to develop systems that allow the deployment of UAVs in disaster scenarios, in order to aid first responders with collecting imagery and other sensory data without putting human lives at risk. In particular, work has focused on developing autonomous systems to minimise the involvement of overstretched first responder personnel, and to ensure action can be taken by the UAVs quickly, co-operatively, and with close to optimal results. Key to this work, is the idea of enabling coordinated UAVs to explore a disaster space to discover incidents and then to allow more detailed examination, imagery, or sensing of these locations. Consequently, in this thesis we examine the challenge of coordinating exploratory and task-responsive UAVs in the presence of prior (but uncertain) beliefs about incident locations, and the combination of their roles together. To do this, we first identify the key components of such a system as: path planning, task allocation, and using belief data for predictive UAV placement. Subsequently, we introduce our contributions in the form of a complete, decentralised system for a single explorative path planner to minimise the time to identify incidents, to allocate incidents to UAVs as tasks, and to place UAVs prior to new tasks being found. Having demonstrated the efficacy of this solution in experimental scenarios, we extend the formulation of our explorative path-planning problem to multiple UAVs by constructing a coordinated, factored Monte-Carlo Tree Search algorithm for use in a discretised space representation of a disaster area. Subsequently, we detail the performance of our new algorithm against uncoordinated alternatives using real data from the 2010 Haiti earthquake. We demonstrate the performance benefits of our method via the metric of people discovered in the simulation; showing improvements of up to 23% in cases with ten UAVs. This is the first application of this technique to very large action spaces of the type encountered in realistic disaster scenarios. Finally, we modify our coordinated exploration algorithm to function in a continuous action space. This represents the first example of a continuous factored coordinated Monte-Carlo Tree Search algorithm. We evaluated this algorithm on the same Haiti dataset as the discretised version, but with a new sensor model simulating mobile phone signal detection to represent the types of sensors deployed by first responders. In addition to the benefits of a more realistic model of the environment, we found improvements in survivor localisation times of up to 20% over the discrete algorithm; demonstrating the value in our approach. As such, the contributions presented in this thesis advance the state of the art in UAV coordination algorithms, and represent a progression towards the widespread deployment of autonomous platforms that can aid rescue workers in disaster situations and—ultimately—save lives.
4
Jones, E. R. Ll. "The general pole placement problem in singular systems." Thesis, Loughborough University, 1991. https://dspace.lboro.ac.uk/2134/31932.
Full textAbstract:
Over the last decade infinite poles and zeros have been recognised as having fundamental relevance to the analysis of the dynamical behaviour of a system. Indeed even the classical theory of characteristic root loci alludes to the existence of infinite zeros without defining them as such whilst the significance of the infinite poles has more recently emerged in the study of non-proper systems.
5
Furfaro, Roberto. "Radiative transport in plant canopies: Forward and inverse problem for UAV applications." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280700.
Full textAbstract:
This dissertation deals with modeling the radiative regime in vegetation canopies and the possible remote sensing applications derived by solving the forward and inverse canopy transport equation. The aim of the research is to develop a methodology (called "end-to-end problem solution") that, starting from first principles describing the interaction between light and vegetation, constructs, as the final product, a tool that analyzes remote sensing data for precision agriculture (ripeness prediction). The procedure begins by defining the equations that describe the transport of photons inside the leaf and within the canopy. The resulting integro-differential equations are numerically integrated by adapting the conventional discrete-ordinate methods to compute the reflectance at the top of the canopy. The canopy transport equation is also analyzed to explore its spectral properties. The goal here is to apply Case's method to determine eigenvalues and eigenfunctions and to prove completeness. A model inversion is attempted by using neural network algorithms. Using input-outputs generated by running the forward model, a neural network is trained to learn the inverse map. The model-based neural network represents the end product of the overall procedure. During Oct 2002, an Unmanned Aerial Vehicles (UAVs) equipped with a camera system, flew over Kauai to take images of coffee field plantations. Our goal is to predict the amount of ripe coffee cherries for optimal harvesting. The Leaf-Canopy model was modified to include cherries as absorbing and scattering elements and two classes of neural networks were trained on the model to learn the relationship between reflectance and percentage of ripe, over-ripe and under-ripe cherries. The neural networks are interfaced with images coming from Kauai to predict ripeness percentage. Both ground and airborne images are considered. The latter were taken from the on-board Helios UAV camera system flying over the Kauai coffee field. The results are compared against hand counts and parchment data to evaluate the network performances on real applications. In ground images, the error is always less than 11%. In airborne image, the error bound is 20%. The results are certainly adequate and show the tremendous potential of the methodology.
6
Jung, Changyong. "ON RELAY NODE PLACEMENT PROBLEM FOR SURVIVABLE WIRELESS SENSOR NETWORKS." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/570.
Full textAbstract:
Wireless sensor networks are widely applied to many fields such as animal habitat monitoring, air traffic control, and health monitoring. One of the current problems with wireless sensor networks is the ability to overcome communication failures due to hardware failure, distributing sensors in an uneven geographic area, or unexpected obstacles between sensors. One common solution to overcome this problem is to place a minimum number of relay nodes among sensors so that the communication among sensors is guaranteed. This is called Relay Node Placement Problem (RNP). This problem has been proved as NP-hard for a simple connected graph. Therefore, many algorithms have been developed based on Steiner graphs. Since RNP for a connected graph is NP-hard, the RNP for a survivable network has been conjectured as NP-hard and the algorithms for a survivable network have also been developed based on Steiner graphs. In this study, we show the new approximation bound for the survivable wireless sensor networks using the Steiner graphs based algorithm. We prove that the approximation bound is guaranteed in an environment where some obstacles are laid, and also propose the newly developed algorithm which places fewer relay nodes than the existing algorithms. Consequently, the main purpose of this study is to find the minimum number of relay nodes in order to meet the survivability requirements of wireless sensor networks.
7
Ernest, Nicholas D. "UAV Swarm Cooperative Control Based on a Genetic-Fuzzy Approach." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1337954828.
Full text
8
Ural, Mustafa. "Solution Of The Antenna Placement Problem By Means Of Global Optimization Techniques." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612674/index.pdf.
Full textAbstract:
In this thesis work, minimization of platform-based coupling between the antennas of two VHF radios on an aircraft platform and two HF radios on a ship platform is aimed. For this purposean optimal antenna placement, which yields minimum average coupling between the antennas over the whole frequency band of operation is determined for each platform. Two important global optimization techniques, namely Genetic Algorithm Optimization and Particle Swarm Optimization, are used in determination of these optimal antenna placements. Aircraft &
ship platforms and antennas placed on them are modeled based on their real electrical and physical properties in CST &ndash
MWS (Microwave Studio) simulation tool. For each platform, antenna placements and coupling results determined by two different optimization techniques and performances of these optimization techniques are compared with each other. At the end of this thesis work
for each platform, far-field radiation pattern performances of the antennas at their optimal places are analyzed in terms of directivity and coverage.
9
Mofya, Enock Chisonge. "Exact and Heuristic Algorithms for Solving the Generalized Minimum Filter Placement Problem." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1311%5F1%5Fm.pdf&type=application/pdf.
Full text
10
Haslum, Patrik. "Prediction as a Knowledge Representation Problem : A Case Study in Model Design." Licentiate thesis, Linköping University, Linköping University, KPLAB - Knowledge Processing Lab, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5724.
Full textAbstract:
The WITAS project aims to develop technologies to enable an Unmanned Airial Vehicle (UAV) to operate autonomously and intelligently, in applications such as traffic surveillance and remote photogrammetry. Many of the necessary control and reasoning tasks, e.g. state estimation, reidentification, planning and diagnosis, involve prediction as an important component. Prediction relies on models, and such models can take a variety of forms. Model design involves many choices with many alternatives for each choice, and each alternative carries advantages and disadvantages that may be far from obvious. In spite of this, and of the important role of prediction in so many areas, the problem of predictive model design is rarely studied on its own.
In this thesis, we examine a range of applications involving prediction and try to extract a set of choices and alternatives for model design. As a case study, we then develop, evaluate and compare two different model designs for a specific prediction problem encountered in the WITAS UAV project. The problem is to predict the movements of a vehicle travelling in a traffic network. The main difficulty is that uncertainty in predictions is very high, du to two factors: predictions have to be made on a relatively large time scale, and we have very little information about the specific vehicle in question. To counter uncertainty, as much use as possible must be made of knowledge about traffic in general, which puts emphasis on the knowledge representation aspect of the predictive model design.
The two mode design we develop differ mainly in how they represent uncertainty: the first uses coarse, schema-based representation of likelihood, while the second, a Markov model, uses probability. Preliminary experiments indicate that the second design has better computational properties, but also some drawbacks: model construction is data intensive and the resulting models are somewhat opaque.
Report code: LiU-Tek-Lic-2002:15.
11
Altman, James Ross. "A Practical Comprehensive Approach to PMU Placement for Full Observability." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/31200.
Full textAbstract:
In recent years, the placement of phasor measurement units (PMUs) in electric transmission systems has gained much attention. Engineers and mathematicians have developed a variety of algorithms to determine the best locations for PMU installation. But often these placement algorithms are not practical for real systems and do not cover the whole process. This thesis presents a strategy that is practical and addresses three important topics: system preparation, placement algorithm, and installation scheduling. To be practical, a PMU strategy should strive for full observability, work well within the heterogeneous nature of power system topology, and enable system planners to adapt the strategy to meet their unique needs and system configuration. Practical considerations for the three placement topics are discussed, and a specific strategy based on these considerations is developed and demonstrated on real transmission system models.Master of Science
12
Benarab, Amina. "Contribution to the partial pole placement problem for some classes of time-delay systems with applications." Electronic Thesis or Diss., université Paris-Saclay, 2022. http://www.theses.fr/2022UPAST136.
Full textAbstract:
Une des questions d'intérêt pour les systèmes linéaires à retard est de déterminer les conditions sur les paramètres de l'équation qui garantissent la stabilité exponentielle des solutions. En général, c'est un véritable défi d'établir des conditions sur les paramètres du système afin de garantir une telle stabilité. L'une des approches efficaces dans l'analyse de stabilité des systèmes à retard est l'approche fréquentielle. Dans le domaine de Laplace, l'analyse de stabilité revient à étudier la distribution des racines des fonctions quasipolynomiales caractéristiques. Une fois la stabilité d'un système à retard prouvée, il est important de caractériser le taux de décroissance exponentielle des solutions de ces systèmes. Dans le domaine fréquentiel, ce taux de décroissance correspond à la valeur spectrale dominante. Des travaux récents ont mis en évidence le lien entre la multiplicité maximale et les racines dominantes. En effet, les conditions pour qu'une racine multiple donnée soit dominante sont étudiées, cette propriété est connue sous le nom de Multiplicity-Induced-Dominancy (MID). Dans cette thèse, trois sujets liés à la propriété MID sont étudiés. Premièrement, l'effet des racines multiples avec des multiplicités admissibles présentant, sous des conditions appropriées, la validité de la propriété MID pour les équations différentielles neutres du second ordre avec un seul retard est exploré. La stabilisation de l'oscillateur classique bénéficie des résultats obtenus. Deuxièmement, les effets des retards sur la stabilité des véhicules aériens sans pilote (UAV) sont exploités. À cet égard, une application symbolique/numérique de la propriété MID dans le contrôle des drones à rotor avec des retards est fournie. Enfin, la stabilisation d'une balance à roulettes par le biais de la propriété MID est considéréeOne of the questions of ongoing interest for linear time-delay systems is to determine conditions on the equation's parameters that guarantee the exponential stability of solutions. In general, it is quite a challenge to establish conditions on the parameters of the system in order to guarantee such a stability. One of the effective approaches in the stability analysis of time-delay systems is the frequency domain approach. In the Laplace domain, the stability analysis amounts to study the distribution of characteristic quasipolynomial functions' roots. Once the stability of a delay system has been proven, it is important to characterize the exponential decay rate of the solutions of such systems. In the frequency domain, this decay rate corresponds to the dominant spectral value. Recent works emphasized the link between maximal multiplicity and dominant roots. Indeed, conditions for a given multiple root to be dominant are investigated, this property is known as Multiplicity-Induced-Dominancy (MID). In this dissertation, three topics related to the MID property are investigated. Firstly, the effect of multiple roots with admissible multiplicities exhibiting, under appropriate conditions, the validity of the MID property for second-order neutral time-delay differential equations with a single delay is explored. The stabilization of the classical oscillator benefits from the obtained results. Secondly, the effects of time-delays on the stability of Unmanned Aerial Vehicles (UAVs) is exploited. In this regard, a symbolic/numeric application of the MID property in the control of UAV rotorcrafts featuring time-delays is provided. Lastly, the stabilization of a rolling balance board by means of the MID property is considered
13
Anderson, Heather. "Analyzing AP Syllabi for Problem Solving, Authentic Learning, and Collaborative Learning Practices." Thesis, University of Oregon, 2014. http://hdl.handle.net/1794/18323.
Full textAbstract:
A rubric was used to determine the frequency of college-readiness practices of Problem Solving, Authentic Learning, and Collaborative Learning present in Advanced Placement Calculus and English syllabi. Chi square tests were conducted and determined Problem Solving, Authentic Learning, and Collaborative Learning were found significantly more often in the English syllabi than in the Calculus syllabi. Problem Solving and its subcomponents understanding the problem and strategizing, as well as the Collaborative Learning subcomponent dialogue, were found in the English syllabi more than in the Calculus syllabi. The Collaborative Learning subcomponent reciprocal teaching was found more frequently in the English Literature and Composition syllabi while peer review was found most often in English Language and Composition syllabi and not analyzed for its presence in the Calculus syllabi. No significant differences were found between subjects for the Problem Solving subcomponent hypothesizing, Authentic Learning or any of its subcomponents, nor the Collaborative Learning subcomponents using out of class time for study group learning or group projects.
14
Rautu, Dorin Marian. "Déploiement temporaire d'une infrastructure de communication à base de drones." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0086.
Full textAbstract:
Dernièrement, l'utilisation des drones est en pleine expansion dans multiples domaines, par exemple récemment la livraison des colis ou des repas. Parallèlement, les stations de base mobiles sont incapables parfois de satisfaire les exigences des utilisateurs, surtout en cas d'événements imprévus, tels que les catastrophes, les rassemblements ou les rencontres sportives. Une solution prometteuse consiste à profiter de la disponibilité des drones pour pallier les déficiences des réseaux cellulaires en les aidant à satisfaire les demandes par l'extension de la couverture à l'aide des points d'accès installés à bord des drones. Bien que les drones offrent un déploiement rapide, le placement devient l'un des problèmes clés. Dans ce manuscrit nous nous intéressons à ce type de réseaux et au placement des drones en proposant une méthode de déploiement fondée sur une analogie avec la loi de Coulomb, les utilisateurs et les drones agissant comme des charges électriques, les drones étant attirés par les utilisateursRecently, the use of drones is booming in many areas, newly in parcel or meal shippement. Analogue to this deployment,the flexibility and resilience requirements of cellular networks are not always met by terrestrial base stations, mainly in the case of unforeseen events, such as natural disasters, gatherings or sports events. One promising solution is to benefit from the availability of drones in order to fulfill the temporary failures of cellular networks by helping them to meet the demands by extending the coverage using the access points installed onboard the UAVs. Although drones offer rapid deployment, the placement becomes one of the key issues. In this thesis we focus on this type of networks and in the drone placement by proposing a deployment method based on an analogy with Coulomb's law, the users and the drones acting like electric charges, the drones being attracted by users
15
McDaniel, Colleen Marie. "The effects of problem-based learning on student understanding of Advanced Placement® environmental science topics." Montana State University, 2012. http://etd.lib.montana.edu/etd/2012/mcdaniel/McDanielC0812.pdf.
Full textAbstract:
Often during second semester, I lose the attention of my students due to their preoccupation with being second semester seniors and with college acceptances. This project used student-centered, problem-based learning to regain their attention and make them more accountable for their learning in my AP ® Environmental Science course. I also looked at the affect it had on their study strategies, motivation, and metacognition in class, along with my own attitude about teaching. This project investigated the effect that problem-based learning had on understanding of AP ® Environmental Science topics when compared to a traditional teacher-centered lecture based unit. Students understanding of material was assessed using pre and postunit assessments, along with formative assessments, and concept map interviews. Other methods of data collection were used to understand changes in student's attitudes, study methods, and metacognition in all units. The attitude of students was determined through using attitude surveys and individual interviews. Student surveys along with interviews helped understand the changes in study habits and metacognition. Observations made throughout the units also supplied data to analyze these areas. Results indicated a mixed effect on each of the areas addressed. In the first treatment unit there was a positive trend, with improvement in attitude, attainment of knowledge of concepts, and metacognition, but in the second treatment the trend was opposite. The same observation can be made with my attitude toward teaching that in the first unit it was more positive while in the second unit it was more negative.
16
Reeder, Richard C. "Mainstream Success Following Placement in a Modified Type II Setting." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4753/.
Full textAbstract:
The topic of alternative schools is widely available in the literature; however, once a student has been labeled a "troublemaker" and has been placed in a District Alternative Education Program (DAEP), a Type II setting, there is limited information about the overall success of students upon their return to the mainstream. This study compared the success of students formerly placed in a modified disciplinary Type II setting, once they have returned to the mainstream, with their success prior to disciplinary placement. The purpose of the study was to examine if disciplinary measures that remove students from the mainstream environment negatively impact the variables that measure school success, despite legislative mandates such as No Child Left Behind, which advocates success for every student. The population for this study was 86 7th- through 11th-grade students assigned to a DAEP in Texas during the spring of 2003. A comparison of pre- and post-placement dependent variables measuring school success-attendance, passing core courses, behavioral achievement, standardized test score achievement, recidivism, and dropout rates-comprised this study. The independent variables-gender, ethnicity, grade level, socioeconomic status, and disciplinary offense-were used to compare and analyze each dependent variable. The dependent variables of attendance, passing core courses, and behavior demonstrated a decline in the measurement of school success across time. The only dependent variable that demonstrated improvement between the pre- and post-placement periods was achievement on standardized test scores. From the number of students who withdrew from the mainstream during the post-placement semesters, large recidivism and dropout rates were determined, which reflected the large percentage of students who were not successful in the district's mainstream. The comparisons of dependent variables by independent variables resulted in significance only in the analyses of attendance by grade level. This interaction was determined to be significant since p < .05. During both post-placement semesters, 11th-grade attendance increased by 20.2 points. Students in the 7th, 8th, and 9th grades maintained a slight increase in attendance between the pre-placement and first post-placement semester yet experienced an attendance decline in the second post-placement semester. This decline was seen in all three grade levels between the pre-placement and the second post-placement semesters. Attendance among tenth graders declined throughout all semesters of the study. The comparison of attendance by disciplinary offense resulted in a large effect size (eta2). The eta2 reported within 29.8% accuracy in variability when attendance was compared by disciplinary offense. Students placed for assault demonstrated a 27.7 point increase in attendance by the second post-placement semester. Despite the comparison of attendance by the grade level of students being the only significant result, and the comparison of attendance by disciplinary offense resulting in a large effect size, several specific conclusions were drawn from the analyses of the pre- and post-placement data measuring school success. All dependent variable measurements, with the exception of standardized test score achievement, resulted in an overall reduction of mean scores across time. This decline indicates that students do demonstrate a decline in school success following a removal from a mainstream setting.
17
Valicov, Petru. "Problèmes de placement, de coloration et d’identification." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14549/document.
Full textAbstract:
Dans cette thèse, nous nous intéressons à trois problèmes issus de l'informatique théorique, à savoir le placement de formes rectangulaires dans un conteneur (OPP), la coloration dite "forte" d'arêtes des graphes et les codes identifiants dans les graphes. L'OPP consiste à décider si un ensemble d'items rectangulaires peut être placé sans chevauchement dans un conteneur rectangulaire et sans dépassement des bords de celui-ci. Une contrainte supplémentaire est prise en compte, à savoir l'interdiction de rotation des items. Le problème est NP-difficile même dans le cas où le conteneur et les formes sont des carrés. Nous présentons un algorithme de résolution efficace basé sur une caractérisation du problème par des graphes d'intervalles, proposée par Fekete et Schepers. L'algorithme est exact et utilise les MPQ-arbres - structures de données qui encodent ces graphes de manière compacte tout en capturant leurs propriétés remarquables. Nous montrons les résultats expérimentaux de notre approche en les comparant aux performances d'autres algorithmes existants. L'étude de la coloration forte d'arêtes et des codes identifiants porte sur les aspects structurels et de calculabilité de ces deux problèmes. Dans le cas de la coloration forte d'arêtes nous nous intéressons plus particulièrement aux familles des graphes planaires et des graphes subcubiques. Nous montrons des bornes optimales pour l'indice chromatique fort des graphes subcubiques en fonction du degré moyen maximum et montrons que tout graphe planaire subcubique sans cycles induits de longueur 4 et 5 est coloriable avec neuf couleurs. Enfin nous confirmons la difficulté du problème de décision associé, en prouvant qu'il est NP-complet dans des sous-classes restreintes des graphes planaires subcubiques.La troisième partie de la thèse est consacrée aux codes identifiants. Nous proposons une caractérisation des graphes identifiables dont la cardinalité du code identifiant minimum ID est n-1, où n est l'ordre du graphe. Nous étudions la classe des graphes adjoints et nous prouvons des bornes inférieures et supérieures serrées pour le paramètre ID dans cette classe. Finalement, nous montrons qu'il existe un algorithme linéaire de calcul de ID dans la classe des graphes adjoints L(G) où G a une largeur arborescente bornée par une constante. En revanche nous nous apercevons que le problème est NP-complet dans des sous-classes très restreintes des graphes parfaitsIn this thesis we study three theoretical computer science problems, namely the orthogonal packing problem (OPP for short), strong edge-colouring and identifying codes.OPP consists in testing whether a set of rectangular items can be packed in a rectangular container without overlapping and without exceeding the borders of this container. An additional constraint is that the rotation of the items is not allowed. The problem is NP-hard even when the problem is reduced to packing squares in a square. We propose an exact algorithm for solving OPP efficiently using the characterization of the problem by interval graphs proposed by Fekete and Schepers. For this purpose we use some compact representation of interval graphs - MPQ-trees. We show experimental results of our approach by comparing them to the results of other algorithms known in the literature. we observe promising gains.The study of strong edge-colouring and identifying codes is focused on the structural and computational aspects of these combinatorial problems. In the case of strong edge-colouring we are interested in the families of planar graphs and subcubic graphs. We show optimal upper bounds for the strong chromatic index of subcubic graphs as a function of the maximum average degree. We also show that every planar subcubic graph without induced cycles of length 4 and 5 can be strong edge-coloured with at most nine colours. Finally, we confirm the difficulty of the problem by showing that it remains NP-complete even in some restricted classes of planar subcubic graphs.For the subject of identifying codes we propose a characterization of non-trivial graphs having maximum identifying code number ID, that is n-1, where n is the number of vertices. We study the case of line graphs and prove lower and upper bounds for ID parameter in this class. At last we investigate the complexity of the corresponding decision problem and show the existence of a linear algorithm for computing ID of the line graph L(G) where G has the size of the tree-width bounded by a constant. On the other hand, we show that the identifying code problem is NP-complete in various subclasses of planar graphs
18
Oliveira, Diogo. "Multi-Objective Resource Provisioning in Network Function Virtualization Infrastructures." Scholar Commons, 2018. http://scholarcommons.usf.edu/etd/7206.
Full textAbstract:
Network function virtualization (NFV) and software-dened networking (SDN) are two recent networking paradigms that strive to increase manageability, scalability, pro- grammability and dynamism. The former decouples network functions and hosting devices, while the latter decouples the data and control planes. As more and more service providers adopt these new paradigms, there is a growing need to address multi-failure conditions, particularly those arising from large-scale disaster events. Overall, addressing the virtual network function (VNF) placement and routing problem is crucial to deploy NFV surviv- ability. In particular, many studies have inspected non-survivable VNF provisioning, however no known work have proposed survivable/resilient solutions for multi-failure scenarios. In light of the above, this work proposes and deploys a survivable multi-objective provisioning solution for NFV infrastructures. Overall, this study initially proposes multi- objective solutions to eciently solve the VNF mapping/placement and routing problem. In particular, a integer linear programming (ILP) optimization and a greedy heuristic meth- ods try to maximize the requests acceptance rate while minimizing costs and implementing trac engineering (TE) load-balancing. Next, these schemes are expanded to perform \risk- aware" virtual function mapping and trac routing in order to improve the reliability of user services. Furthermore, additionally to the ILP optimization and greedy heuristic schemes, a metaheuristic genetic algorithm (GA) is also introduced, which is more suitable for large- scale networks. Overall, these solutions are then tested in idealistic and realistic stressor scenarios in order to evaluate their performance, accuracy and reliability.
19
McFarland, Mary Joanne 1946. "Staff use of the problem and needs assessment questionnaire (PNAQ) in client placement and intervention decisions: A process evaluation." Thesis, The University of Arizona, 1994. http://hdl.handle.net/10150/558229.
Full text
20
Afana, Margaret Cecilia. "The most appropriate educational placement for seriously emotionally disturbed children in residential care." CSUSB ScholarWorks, 1997. https://scholarworks.lib.csusb.edu/etd-project/1191.
Full textAbstract:
This research project utilized a post-positivist design for the purpose of exploring and determining the most appropriate educational placement for seriously emotionally disturbed children who reside in residential care and who are considered to be "high risk," both educationally and socially. It was the goal of the study, through qualitative research, to establish a basis for the successful education and social integration of SED children.
21
Lovell, Bonnie R. "Development of a Studio Art Curriculum for the Concentration Section of the Advanced Placement Drawing Portfolio." Digital Archive @ GSU, 2006. http://digitalarchive.gsu.edu/art_design_theses/11.
Full textAbstract:
This thesis presents an Advanced Placement curriculum for the concentration section of the Drawing Portfolio. It is intended as a teaching tool to encourage and develop creative strategies related to idea generation and refinement based on creative problem solving, which is essential to the development of an effective concentration. One of the most difficult problems faced by Advanced Placement Studio Art students is idea generation for the artwork related to a central topic for the concentration section of their portfolios. This curriculum introduces lessons based on artist research, brainstorming, synectics, and SCAMPER techniques designed to foster creative idea generation for artwork development. It also gives students a tool with which to analyze the ideas generated based on specific criteria necessary to the concentration. This curriculum specifically encourages the creative process in students and provides teachers with a foundation with which to begin a unique and highly personal journey by the individual student.
22
Kantharaj, Krithica. "Evaluating Coverage Models for Emergency Services: A Case Study of Emergency Siren Placement in Lucas County, OH." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1384525360.
Full text
23
Pereira, Marciel Barros. "Particle swarm optimization and differential evolution for base station placement with multi-objective requirements." reponame:Repositório Institucional da UFC, 2015. http://www.repositorio.ufc.br/handle/riufc/13374.
Full textAbstract:
PEREIRA, M. B. Particle swarm optimization and differential evolution for base station placement with multi-objective requirements. 2015. 72 f. Dissertação (Mestrado em Engenharia de Teleinformática) – Centro de Tecnologia, Universidade Federal do Ceará, Fortaleza, 2015.Submitted by Marlene Sousa (mmarlene@ufc.br) on 2015-09-21T12:31:09Z No. of bitstreams: 1 2015_dis_mbpereira.pdf: 3666612 bytes, checksum: bc2466a863d5e64d596e5667f3ef5426 (MD5)
Approved for entry into archive by Marlene Sousa(mmarlene@ufc.br) on 2015-10-09T14:45:25Z (GMT) No. of bitstreams: 1 2015_dis_mbpereira.pdf: 3666612 bytes, checksum: bc2466a863d5e64d596e5667f3ef5426 (MD5)
Made available in DSpace on 2015-10-09T14:45:26Z (GMT). No. of bitstreams: 1 2015_dis_mbpereira.pdf: 3666612 bytes, checksum: bc2466a863d5e64d596e5667f3ef5426 (MD5) Previous issue date: 2015-07-15
The infrastructure expansion planning in cellular networks, so called Base Station Placement (BSP) problem, is a challenging task that must consider a large set of aspects, and which cannot be expressed as a linear optimization function. The BSP is known to be a NP-hard problem unable to be solved by any deterministic method. Based on some fundamental assumptions of Long Term Evolution - Advanced (LTE-A) networks, this work proceeds to investigate the use of two methods for BSP optimization task: the Particle Swarm Optimization (PSO) and the Differential Evolution (DE), which were adapted for placement of many new network nodes simultaneously. The optimization process follows two multi-objective functions used as fitness criteria for measuring the performance of each node and of the network. The optimization process is performed in three scenarios where one of them presents actual data collected from a real city. For each scenario, the fitness performance of both methods as well as the optimized points found by each technique are presented
O planejamento de expansão de infraestrutura em redes celulares é uma desafio que exige considerar diversos aspectos que não podem ser separados em uma função de otimização linear. Tal problema de posicionamento de estações base é conhecido por ser do tipo NP-hard, que não pode ser resolvido por qualquer método determinístico. Assumindo características básicas da tecnologia Long Term Evolution (LTE)-Advanced (LTE-A), este trabalho procede à investigação do uso de dois métodos para otimização de posicionamento de estações base: Otimização por Enxame de Partículas – Particle Swarm Optimization (PSO) – e Evolução Diferencial – Differential Evolution (DE) – adaptados para posicionamento de múltiplas estações base simultaneamente. O processo de otimização é orientado por dois tipos de funções custo com multiobjetivos, que medem o desempenho dos novos nós individualmente e de toda a rede coletivamente. A otimização é realizada em três cenários, dos quais um deles apresenta dados reais coletados de uma cidade. Para cada cenário, são exibidos o desempenho dos dois algoritmos em termos da melhoria na função objetivo e os pontos encontrados no processo de otimização por cada uma das técnicas
24
Holmberg, Linnea. "Elevers erfarenheter av textuppgifter med varierad frågeplacering : En kvalitativ intervjuundersökning med sex elever i årskurs 5." Thesis, Högskolan i Jönköping, Högskolan för lärande och kommunikation, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-31934.
Full textAbstract:
Studien behandlar sex elevers erfarenheter av matematiska textuppgifter där frågans placering varierar. Det undersöks eftersom tidigare forskning inte har undersökt frågans placering utifrån elevernas perspektiv. Tidigare forskning har enbart undersökt elevers lösningar av textuppgifter där frågeplaceringen varierat. Syftet med studien var att undersöka hur sex elever i årskurs 5 erfar matematiska textuppgifter med två olika placeringar av frågan, i slutet och i början av uppgifterna. Undersökningen hade fenomenologi som vetenskaplig teori. I studien intervjuades sex elever medan de löste sex textuppgifter med varierad placering av frågan. Under intervjuerna svarade eleverna på frågor som bland annat berörde textuppgifternas svårighetsgrad och frågans placering. Resultatet av studien visar att elevernas tillvägagångssätt för att lösa uppgifterna inte skilde sig i förhållande till frågans placering. De textuppgifter som eleverna ansåg var svårast hade frågan i början. När frågan var i början ansåg flertalet elever att de, när de läste uppgiften, fokuserade på vad som skulle räknas ut. Trots det föredrog eleverna textuppgifter med frågan i slutet eftersom de var vana vid det. Slutsatsen som kan dras av studien är att eleverna föredrog att frågan var i slutet av skriftliga textuppgifter.This study discusses six students' experiences of mathematical word problems with different locations of the questions. This was investigated because previous research has not investigated the students' perspectives of question placement. Previous research has only investigated students' solutions of word problems with different locations of the questions. The aim of this study was to investigate how six students, between 11 and 12 years old, in 5th grade experienced mathematical word problems with different locations of the question. The question was either located in the end or in the beginning of the word problem. The study had phenomenology as a scientific theory. This study was done by interviewing each one of the six students while they solved six written mathematical word problems with different location of the question. During the interviews, the students answered questions about for example the difficulty of the word problems and question placement. The result of the study showed that the students' methods to solve the word problems did not differ in relation to where the question was located. The most difficult word problems according to the students had the question in the beginning. The difficulty of the word problems was also affected by which type of problem it was; change problem, combine problem or compare problem. When the question was located in the beginning of the word problem most students perceived that they focused on the calculation of the problem. However, the students preferred word problems with the question in the end because they were used to that. The conclusion is that students preferred the question in the end of written word problems.
25
Müller, Lucas Fernando. "Survivor : estratégias de posicionamento de controladores orientadas à sobrevivência em redes definidas por software." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/115065.
Full textAbstract:
O paradigma SDN simplifica o gerenciamento da rede ao concentrar todas as tarefas de controle em uma única entidade, o controlador. Nesse modo de operação, os dispositivos de encaminhamento só funcionam de forma completa enquanto conectados a um controlador. Neste contexto, a literatura recente identificou questões fundamentais, como o isolamento de dispositivos em função de disrupções na rede e a sobrecarga de um controlador, e propôs estratégias de posicionamento do controlador para enfrentá-las. Contudo, as propostas atuais têm limitações cruciais: (i) a conectividade dispositivo-controlador é modelada usando um único caminho, ainda que na prática possam ocorrer múltiplas conexões concorrentes; (ii) alterações no comportamento da chegada de novos fluxos são manipulados sob demanda, assumindo que a rede em si pode sustentar altas taxas de requisição; e (iii) mecanismos de recuperação de falhas requerem informações pré-definidas, que, por sua vez, não são otimizadas. Esta dissertação apresenta Survivor, uma nova abordagem de posicionamento do controlador para redes WAN que visa enfrentar esses desafios. A abordagem trata três aspectos de forma explícita durante o projeto da rede: a conectividade, a capacidade e a recuperação. Além disso, tais aspectos são planejados para dois estados distintos da rede: pré e pós-disrupção. Em outras palavras, a rede é configurada da melhor forma tanto para operação normal, quanto para operação após eventos de disrupção. Para este fim, a abordagem é dividida em duas etapas. A primeira define o posicionamento de instâncias do controlador, enquanto a segunda especifica uma lista de controladores de backup para cada dispositivo na rede. Ademais, são desenvolvidas duas estratégias com base na abordagem Survivor. A primeira, implementada em Programação Linear Inteira, garante uma solução ótima a um custo computacional alto. A segunda, implementada através de heurísticas, fornece soluções sub-ótimas a um custo computacional muito mais baixo. Comparações com o estado-da-arte mostram que a abordagem Survivor provê ganhos significativos na sobrevivência (identificado na probabilidade mais baixa de perda de conectividade) e no estado convergente da rede através de mecanismos de recuperação mais inteligentes.The SDN paradigm simplifies network management by focusing all control tasks into a single entity, the controller. In this way, forwarding devices can only operate correctly while connected to a logically centralized controller. Within this context, recent literature identified fundamental issues, such as device isolation due to disruptions in the network and controller overload, and proposed controller placement strategies to tackle them. However, current proposals have crucial limitations: (i) device-controller connectivity is modeled using single paths, yet in practice multiple concurrent connections may occur; (ii) peaks in the arrival of new flows are only handled on-demand, assuming that the network itself can sustain high request rates; and (iii) failover mechanisms require predefined information which, in turn, has been overlooked. This dissertation presents Survivor, a novel controller placement approach for WAN networks that addresses these challenges. The approach explicitly considers the following three aspects in the network design process: connectivity, capacity and recovery. Moreover, these aspects are planned for two distinct states of the network: pre and postdisruption. In other words, the network is configured optimally for both normal operation and for operation after disruption events. To this end, the approach is divided into two steps. The first defines the positioning of the controller instances, and the second specifies a list of backup controllers for each device on the network. Moreover, two strategies based on Survivor are developed. The first strategy, implemented with Integer Linear Programming, guarantees an optimal solution with a high computational cost. The second strategy, implemented using heuristics, provides sub-optimal solutions with a much lower computational cost. Comparisons to the state-of-the-art show that the Survivor approach provides significant increases in network survivability (identified with the lowest probability of connectivity loss) and converged network state through smarter recovery mechanisms.
26
Elloumi, Mouna. "Surveillance de cibles mobiles fondée sur un réseau de drones." Thesis, Toulouse, INPT, 2019. https://oatao.univ-toulouse.fr/25918/1/Elloumi_Mouna.pdf.
Full textAbstract:
Les systèmes fondés sur les drones constituent une solution appropriée pour la surveillance, en particulier des cibles mobiles. La grande mobilité des drones, leur faible coût de maintenance, la facilité de leur déploiement et leur capacité de vol stationnaire, font d'eux une solution intéressante pour la surveillance de cibles mobiles. Notre première contribution concerne le scénario où un seul drone surveille une seule cible mobile. Pour ce cas, nous avons proposé une méthode pour gérer la mobilité du drone, qui assure un suivi continu d'une cible mobile et qui permet d'économiser la consommation en énergie du drone. Les trajectoires du drone ont été calculées en fonction de la position de la cible par rapport au centre du champ de vision du drone. Nous avons considéré pour cela trois zones, et selon la position de la cible par rapport à ces trois zones, le drone fait des ajustements différents, pour minimiser les déplacements inutiles. Notre deuxième contribution concerne le scénario où plusieurs drones surveillent plusieurs cibles mobiles. Pour ce cas, nous avons proposé des méthodes adaptatives pour gérer le placement et le déplacement des drones. Nous avons appliqué ces méthodes dans le contexte de la surveillance du trafic routier. Les trajectoires des drones ont été adaptées, soit en fonction des positions des groupes de véhicules, soit en fonction des positions des événements de la route (embouteillages et excès de vitesse). Ces méthodes assurent la couverture des véhicules, la détection des événements anormaux et la diminution de la consommation d'énergie des drones. Nous avons utilisé une combinaison de l'architecture centralisée et de l'architecture distribuée, en effet les communications entre les drones et avec le point central sont toutes possibles. La communication est faite via des liaisons LTE. Nous nous sommes intéressés à des traces de mobilité réelles de véhicules et à des traces de mobilité générées par un modèle de mobilité véhiculaire qui utilise des plans de routes réelles. Nous avons étudié l'influence des traces de mobilité des véhicules utilisées sur les performances des méthodes de gestion de mobilité des dronesUAV-based systems are an appropriate solution for surveillance, especially for mobile targets. The high mobility of UAVs, their low maintenance costs, their easy deployment and their hovering capability make them an attractive solution for mobile target monitoring. Our first contribution deals with the scenario where a single UAV monitors a single moving target. For this case, we have proposed a method to manage the mobility of the UAV, which ensures a continuous monitoring of a mobile target and which reduces the energy consumption of the UAV. The trajectories of the UAV were calculated according to the distance between the position of the target and the center of the UAV's field of view. We have considered three zones, and depending on the position of the target in those three zones, the UAV makes different adjustments to minimize unnecessary movements. Our second contribution deals with the scenario where several drones monitor multiple moving targets. For this case, we proposed adaptive methods to manage the placement and movement of UAVs. We applied these methods in the context of road traffic monitoring. The trajectories of UAVs have been adapted according to the positions of the groups of vehicles, or according to the positions of the events of the road (traffic jams and speeding violations). These methods ensure the coverage of vehicles, the detection of abnormal events and the reduction of energy consumption of UAVs. We have used a combination of the centralized architecture and the distributed architecture, indeed the communications between the UAVs and with the central point are all possible. The communication is done via LTE links. We were interested in real mobility traces of vehicles and mobility traces generated by a vehicular mobility model that uses real road maps. We studied the influence of vehicle mobility traces on the performance of UAV mobility management methods
27
Song, Xiaoxiao. "Layout optimization based on multi-objective interactive approach." Thesis, Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0051.
Full textAbstract:
Dans tous les problèmes d’agencement, les contraintes de non-chevauchement entre composants et les contraintes d’appartenanceau conteneur sont présentes. Un modèle d’agencement multiobjectif avec contraintes fonctionnelles est développé. Intégrer l’accessibilité des composants comme contraintes fonctionnelles assure la maintenance ou le fonctionnement des composants. Cependant, les contraintes fonctionnelles augmentent la complexité d’optimisation d’agencement, notée indice de capacité. Par conséquent, un nouvel algorithme d’optimisation multiobjectif est proposé en utilisant le placement constructif et le recuit simulé pour rechercher des solutions de compromis entre les objectifs multiples. Ensuite, un indicateur de similarité est défini pour évaluer les similaires entre les solutions proposées par l’algorithme. Les expériences indiquent que l’approche d’optimistion proposée fonctionne bien pour garantir l’accessibilité et trouver efficacement des solutions optimales dans les problèmes industriels d’agencement d’espace à un ou plusieurs conteneurs, où l’analyse de similarité démontre une bonne diversité solutions proposées par l’algorithme, qui peut être appliqué en tant qu’outil interactif outil pour leconcepteurThe conventional layout problem is concerned with finding the arrangements of components inside the container to optimize objectives under geometrical constraints, i.e., no component overlap and no container protrusion. A multi-objective layout model with functional constraints is developed. Integrating the accessibility of components as functional constraints ensures components maintenance or proper operation. However, thefunctional constraints increase the layout optimization complexity, denoted as capacity index. Therefore, a novel multi-objective optimizationalgorithm is proposed using the constructive placement and the simulated annealing to search for compromised solutions between the multiple objectives. Thereafter, a similarity indicator is defined to evaluate how similar optimized layout designs are. The experiments indicate that the proposed optimization approach performs well in ensuring accessibility and efficiently finding high-qualified solutions in single- and multi- container layoutapplications, where the similarity analysis demonstrates good diversity of the obtained layout set, which can be applied as an interactive tool
28
Jafarian, Javad. "Modelling and analysis of wireless MAC protocols with applications to vehicular networks." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/modelling-and-analysis-of-wireless-mac-protocols-with-applications-to-vehicular-networks(3695e637-12eb-4fde-9c31-08b3b46e8f55).html.
Full textAbstract:
The popularity of the wireless networks is so great that we will soon reach the point where most of the devices work based on that, but new challenges in wireless channel access will be created with these increasingly widespread wireless communications. Multi-channel CSMA protocols have been designed to enhance the throughput of the next generation wireless networks compared to single-channel protocols. However, their performance analysis still needs careful considerations. In this thesis, a set of techniques are proposed to model and analyse the CSMA protocols in terms of channel sensing and channel access. In that respect, the performance analysis of un-slotted multi-channel CSMA protocols is studied through considering the hidden terminals. In the modelling phase, important parameters such as shadowing and path loss impairments are being considered. Following that, due to the high importance of spectrum sensing in CSMA protocols, the Double-Threshold Energy Detector (DTED) is thoroughly investigated in this thesis. An iterative algorithm is also proposed to determine optimum values of detection parameters in a sensing-throughput problem formulation. Vehicle-to-Roadside (V2R) communication, as a part of Intelligent Transportation System (ITS), over multi-channel wireless networks is also modelled and analysed in this thesis. In this respect, through proposing a novel mathematical model, the connectivity level which an arbitrary vehicle experiences during its packet transmission with a RSU is also investigated.
29
Salas, Donoso Ignacio Antonio. "Packing curved objects with interval methods." Thesis, Nantes, Ecole des Mines, 2016. http://www.theses.fr/2016EMNA0277/document.
Full textAbstract:
Un problème courant en logistique, gestion d’entrepôt, industrie manufacturière ou gestion d’énergie dans les centres de données est de placer des objets dans un espace limité, ou conteneur. Ce problème est appelé problème de placement. De nombreux travaux dans la littérature gèrent le problème de placement en considérant des objets de formes particulières ou en effectuant des approximations polygonales. L’objectif de cette thèse est d’autoriser toute forme qui admet une définition mathématique (que ce soit avec des inégalités algébriques ou des fonctions paramétrées). Les objets peuvent notamment être courbes et non-convexes. C’est ce que nous appelons le problème de placement générique. Nous proposons un cadre de résolution pour résoudre ce problème de placement générique, basé sur les techniques d’intervalles. Ce cadre possède trois ingrédients essentiels : un algorithme évolutionnaire plaçant les objets, une fonction de chevauchement minimisée par cet algorithme évolutionnaire (coût de violation), et une région de chevauchement qui représente un ensemble pré-calculé des configurations relatives d’un objet (par rapport à un autre) qui créent un chevauchement. Cette région de chevauchement est calculée de façon numérique et distinctement pour chaque paire d’objets. L’algorithme sous-jacent dépend également du fait qu’un objet soit représenté par des inégalités ou des fonctions paramétrées. Des expérimentations préliminaires permettent de valider l’approche et d’en montrer le potentielA common problem in logistic, warehousing, industrial manufacture, newspaper paging or energy management in data centers is to allocate items in a given enclosing space or container. This is called a packing problem. Many works in the literature handle the packing problem by considering specific shapes or using polygonal approximations. The goal of this thesis is to allow arbitrary shapes, as long as they can be described mathematically (by an algebraic equation or a parametric function). In particular, the shapes can be curved and non-convex. This is what we call the generic packing problem. We propose a framework for solving this generic packing problem, based on interval techniques. The main ingredients of this framework are: An evolutionary algorithm to place the objects, an over lapping function to be minimized by the evolutionary algorithm (violation cost), and an overlapping region that represents a pre-calculated set of all the relative configurations of one object (with respect to the other one) that creates an overlapping. This overlapping region is calculated numerically and distinctly for each pair of objects. The underlying algorithm also depends whether objects are described by inequalities or parametric curves. Preliminary experiments validate the approach and show the potential of this framework
30
Cioaca, Alexandru George. "A Computational Framework for Assessing and Optimizing the Performance of Observational Networks in 4D-Var Data Assimilation." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/51795.
Full textAbstract:
A deep scientific understanding of complex physical systems, such as the atmosphere, can be achieved neither by direct measurements nor by numerical simulations alone. Data assimilation is a rigorous procedure to fuse information from a priori knowledge of the system state, the physical laws governing the evolution of the system, and real measurements, all with associated error statistics. Data assimilation produces best (a posteriori) estimates of model states and parameter values, and results in considerably improved
computer simulations.
The acquisition and use of observations in data assimilation raises several important scientific questions related to optimal sensor network design, quantification of data impact, pruning redundant data, and identifying the most beneficial additional observations. These questions originate in operational data assimilation practice, and have started to attract considerable interest in the recent past.
This dissertation advances the state of knowledge in four dimensional variational (4D-Var) - data assimilation by developing, implementing, and validating a novel computational framework for estimating observation impact and for optimizing sensor networks. The framework builds on the powerful methodologies of second-order adjoint modeling and the 4D-Var sensitivity equations. Efficient computational approaches for quantifying the observation impact include matrix free linear algebra algorithms and low-rank approximations of the sensitivities to observations. The sensor network configuration problem is formulated as a meta-optimization problem. Best values for parameters such as sensor location are obtained by optimizing a performance criterion, subject to the constraint posed by the 4D-Var optimization. Tractable computational solutions to this "optimization-constrained" optimization problem are provided.
The results of this work can be directly applied to the deployment of intelligent sensors and adaptive observations, as well as to reducing the operating costs of measuring networks, while preserving their ability to capture the essential features of the system under consideration.Ph. D.
31
Fletterman, Manuel. "Designing multimodal public transport networks using metaheuristics." Diss., Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-01162009-154801/.
Full text
32
Sanders, Ian Douglas. "The Axial line placement problem." Thesis, 2002. http://hdl.handle.net/2263/28673.
Full textAbstract:
Visibility, guarding and polygon decomposition are problems in the field of compu¬tational geometry which have roots in real world applications. These problems have been the focus of much research over a number of years. This thesis introduces a new problem in the field - The Axial line Placement Problem - which has some commonalities with these other problems. The problem arises from a consideration of the computational issues that result from attempting to automate the space syntax method. Space syntax is used for describing, quantifying and interpreting the spatial patterns in urban designs by analysing the relationship between the space through which one can move (roads, parks, etc.) and the buildings in the urban layout. In particular, this thesis considers the problem of the placing the axial lines, defining paths along which someone can move, to cross the shared boundaries between the convex polygons which represent the space through which someone can move in the town. A number of simplifications of the original problem are considered in this thesis. The first of these is the problem of placing the smallest number of orthogonal line segments (orthogonal axial lines) to cross the shared boundaries (adjacencies) in a collection of adjacent orthogonal rectangles. This problem is shown to be NP¬Complete by a transformation from the vertex cover problem for planar graphs. A heuristic algorithm which produces an approximation to the general solution is then presented. In addition, special cases of collections of orthogonal rectangles which allow polynomial time solutions are described and algorithms to solve some ofthese special cases are presented. The problem where the axial lines, that pass through the adjacencies between or¬thogonal rectangles, can have arbitrary orientation is then considered. This problem is also shown to be NP-Complete and once again heuristic approaches to solving the problem are considered. The problem of placing axial lines to cross the adjacencies between adjacent convex polygons is a more general case of the problem of placing axial lines of arbitrary orientation in orthogonal rectangles. The NP-Completeness proof can be extended to this problem as well. The final stage of the thesis considers real world urban layouts. Many urban layouts are regular grids of roads. Such layouts can be modelled as general urban grids and this thesis shows that it is possible to find the minimal axial line cover in general urban grids in polynomial time. Some urban layouts are less regular and the idea of a deformed urban grid is introduced to model some of these layouts. A heuristic algorithm that finds a partition of a deformed urban grid in polynomial time is presented and it is conjectured that the axial map of a deformed urban grid can be found in polynomial time. The problem is still open for more general urban layouts which cannot be modelled by deformed urban grids. The contribution of this thesis is that a number of new NP-Complete problems were identified and some new and interesting problems in the area of computational geometry have been introduced.Thesis (DPhil (Computer Science))--University of Pretoria, 2005.
Computer Science
unrestricted
33
Wu, Yung-Chuan, and 吳永全. "Dynamic Placement of UAV-BS for Max-min Fairness on Throughput Performance." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/ujw8f4.
Full textAbstract:
碩士國立交通大學
資訊科學與工程研究所
107
The advance of unmanned aerial vehicle (UAV) technology makes it be able to provide fast aerial service, like taking videos, search and rescue missions, wireless services, etc. UAV base station (UAV-BS) applications become more and more popular in recent years. The placement of UAV-BS is important for area coverage and network throughput of ground users. The current works of UAV-BS placement need to know the locations of ground users. In this work, we proposed a dynamic placement method of UAV-BS to maximize the minimum throughput of ground users without the knowledge of their locations. First, we extract and utilize the wireless channel condition information, the measured throughput of each ground user, from a rate adaptation mechanism. Then, we propose an efficient heuristic placement algorithm with low traversing distance. Last, we obtain simulation results using the free path loss model and trace-driven emulation results using real data collected by a UAV-BS in a real environment
34
Jackson, Marcus James. "Wide-area surveillance system using a UAV helicopter interceptor and sensor placement planning techniques." 2008. http://etd.utk.edu/August2008MastersTheses/JacksonMarcusJames.pdf.
Full text
35
CHANG, LI CHI, and 李季昌. "A Rotatable Placement Algorithm to the Nesting Problem." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/22420454454085995767.
Full textAbstract:
碩士大葉大學
機械工程研究所碩士班
96
The problem about cutting, packing and nesting is a very important subject to the industry. A better full-automatic nesting system, not only can raise the efficiency and simplify manpower, but also increase competitiveness. Because the raw material takes the huge cost for such kind of companies. The objective of two-dimensional optimal nesting problem is to place the same or different pieces of the fixed quantity on the sheet in this paper. What we want to do is increase the rate of utility and decrease the waste of panel. Generally, determine the quality of the nesting results; it can briefly be divided into two factors: placement algorithm and permutation. Placement algorithm means the how to decide the positions where the pieces place into the sheet. And permutation is the placing sequence order of pieces. If the sequence of permutation is available and the placement rule also meets the demand of packing, then the exact or optimal solutions could be found. This research provides a new placement algorithm rule ”Area-Decomposition” method. This combines the rotation function for each piece and genetic algorithm. A comparison of nesting with literature and commercial software shows the results. This research can really receive good results of nesting according to the demand of different situations.
36
Chiang, Mao-Jung, and 江茂榮. "Distributed Approach to Adaptive VNF Manager Placement Problem." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/v25ue5.
Full textAbstract:
碩士國立交通大學
資訊科學與工程研究所
107
Over the last few years, network function virtualization (NFV) has been developing rapidly in both academia and industry since it promises flexible and scalable network management and orchestration. The European Telecommunications Standards Institute (ETSI) has designed NFV management and orchestration (NFV-MANO) architectural framework for the purpose of managing and orchestrating the network services and their corresponding virtualized network functions (VNFs). In the NFV-MANO, the NFV orchestrator (NFVO) manages the network services and coordinates with the VNF managers (VNFMs) which manage the lifecycle of VNFs. It is a challenging problem to determine the placement of VNFMs that keeps the operational cost down without violating the performance requirements. Existing centralized solution that suffers from scalability and privacy issues, in this paper, we leverage potential game theory to achieve distributed solutions to the VNFM placement problem (MPP). More importantly, our distributed solutions hold the property of self-adaptability. It can adapt the changes in the system like some VNFMs are faulty or the number of VNF instances varies. On the other hand, we also show that the game possesses a potential function and admits a Nash equilibrium (NE). Numerical results show the cost efficiency and adaptability of our approaches.
37
Liu, Wei-Li, and 劉威利. "Distributed Approach to Adaptive SDN Controller Placement Problem." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/3e5waf.
Full textAbstract:
碩士國立交通大學
網路工程研究所
107
Software defined network (SDN) has emerged as a new paradigm that provides network programmability, flexibility and efficient network management. The main idea of SDN is splitting the network into application layer, control layer and data layer. In this splitting concept, controller is the brain of SDN network, which manages SDN switch. SDN network performance will be affected by controller location and some metrics such as controller-switch latency, inter-controller latency and controller capacity. It is not easy to determine the location for controllers and number of controllers requirement while meeting the constraint. There existing centralized solution that increases cost and not satisfies constraint when the network dynamics. In this paper, we proposed a potential game which is a distributed mechanism to solve controller placement problem (CPP). Meanwhile, our distributed mechanism have self-stabilizing property that it can adaptively change solution when the network dynamics such as controller failure, link failure and adding nodes. Also, we present our game have exact potential function and end up to Nash equilibrium (NE) eventually. Simulation result shows our approach have adaptability property
38
Tian, Huamei. "Optimal placement of light fixtures for energy saving." Thesis, 2016. http://hdl.handle.net/1828/7097.
Full textAbstract:
Energy consumption of large commercial buildings has become higher than before, and a major part of the energy is on their lighting systems. This thesis aims at reducing the energy consumption of a building's lighting system. Our solution is to minimize the total number of necessary light fixtures in a commercial building, and thus we formulate the Constrained Light Deployment Problem (CLDP). The CLDP problem is tightly related to the Art Gallery Problem (AGP), a classical problem in computational geometry that finds the minimum number of guards to monitor a polygon area. Unlike the traditional AGP, however, our problem poses a new challenge that the illuminance of any spot in the building must be higher than a required threshold. To address the new challenge, we first propose an algorithm based on polygon partition and iteratively remove redundant light fixtures to obtain a tighter upper bound on the necessary number of light fixtures. We further improve the algorithm with clustering and binary search to reduce the number of light fixtures. Our algorithm can return the locations of resulted light fixtures, which are not necessarily the vertices of the orthogonal polygon. Simulation results demonstrate that our algorithm is fast and effective.Graduate
39
Munyaneza, Job. "Solving the antenna placement problem in UMTS networks using genetic algorithms." Thesis, 2009. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000266.
Full textAbstract:
M. Tech. Electrical Engineering.Discusses how to find the best set of base station locations in 3G networks that cover a given number of mobile users with a good quality signal at optimal cost, using Genetic algorithms. The selected approach must alleviate the inefficiencies introduced traditional planning approaches.
40
李嘉裕. "A study of sparse virtual source nodes placement problem in WDM networks." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/93348648294641227891.
Full textAbstract:
碩士國立彰化師範大學
資訊工程學系
95
Using wavelength routing technique for Wavelength Division Multiplexing (WDM) network will definitely be the main framework for network of the next generation. To reduce the number of used wavelengths (or wavelength channels) of multicast transmission, several optical switches in WDM network are equipped with light splitting and wavelength conversion capabilities which are denoted as Virutal Source (VS) nodes. VS node incurs a comparatively higher cost than normal switch, so only some of the switches may provide VS capabilities. Therefore, it is an important isseu that constructs multicast trees by using VS function such that the number of used wavelengths (or wavelength channels) can be minimized. In this thesis, given a positive integer k, and a set of multicast requests, the goal is to determine the location of VS nodes, and determine the routing paths and wavelength assignments for multicast requests, such that the number of used wavelength channels can be minimized. This problem is a NP-hard problem, current approaches used to solve it is to design heurisitic algorithms. In this thesis, a genetic algorithm (GA) is proposed to solve this problem, the goal is to achieve the gobal optimum instead of local optimum. In this thesis, three multicast methods are proposed for establishing multicast tree. These are: (1) Core-Based Tree (CBT), (2) Link Disjoint Cored-Based Tree (LDCBT) and (3) Layered Graph. Experiment results reveal that the reduced ratio of the number of used channels by using GA with CBT, LDCBT and Layered Graph, compared to the results obtained by Max-Degree or Random, in which VS nodes are assigned in a position with the highest degree or in random, respectively. Among these methods, the Layered Graph method can find the best result, and can reduce wavelength channels about 20%. When the demand increases, the CBT method can offer the best performance and can reduce the radio of the number of used channels about 17%.
41
Ho, Chin-Shen, and 何金生. "Application of Differential Evolution to the Capacitor Placement Problem in Distribution Systems." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/13364288688758706013.
Full textAbstract:
碩士國立中正大學
電機工程研究所
87
ABSTRACT With the rapid growth of load demand, the distribution system is becoming very complicated such that the operation efficiency and service quality are deteriorated during recent years. Distribution engineers have to solve the problem by applying various technologies to enhance operation efficiency and improve service quality of distribution systems. Among the various technologies, capacitor addition is the one which has been most commonly used. This research presents an improved method of evolutionary algorithms, called differential evolution, for optimal shunt capacitor allocation planning. Optimal capacitor allocation determines the size and location of capacitors to be installed in a radial distribution feeder that will reduce peak power and energy losses while minimizing the costs of investment and installation of capacitor banks subject to constraints of discrete capacitance and voltage limits. This proposed method employs two additional operations, which are migration technique and sensitivity index method. These two operations are embedded into the original version of differential evolution. Sensitivity index method improves the convergence speed of computation. On the other hand, migration technique avoids falling into a local solution by keeping the diversity among individuals. The proposed method has been applied to three application systems with different selected voltage levels. Computation results show that the method is effective, simple, and promising.
42
Schifano, Robin M. "Overcome evaluation of an elementary-level diciplinary alternative education placement." 2011. http://liblink.bsu.edu/uhtbin/catkey/1660854.
Full textAbstract:
Public school systems are required to provide a safe learning environment free of violence and disruption. For students who threaten the learning of themselves or others, schools frequently develop a disciplinary alternative education placement. Students with a history of behavior problems at school are at greatest risk for future behavior problems and academic failures. In response to evidence that removal discipline techniques had little efficacy, schools have focused on identifying alternative methods of maintaining order and safety. This study evaluated the outcomes of an elementary-level alternative discipline placement with unique intervention programming.
The program includes interventions to increase the effectiveness of traditional alternative discipline placements. Activities focus on promoting social competence and developing social information-processing skills intended to increase the behavioral and academic success of student participants. The program excludes students from the general student population and consists of a behavior management system with gradually increasing behavior expectations, reinforcements and consequences, focused social skills lessons, counseling, and parenting classes.
Participants were consistently lower performing academically than control group students both before and after the program. However, students who experienced fewer discipline removals after the program had higher report card grades. Overall, participants had a decrease in discipline removals after participating in the program but continued to have more lost instruction days due to discipline than control group students. The higher grade level students had less behavior improvement following the program than younger students. No relation was found between a student’s level of success in the program and their academic or behavioral performance changes. Future research needs include a comparison of students referred for persistent misbehavior and those referred for a single, serious incident and the need to assess the specific skills addressed in the program.Department of Educational Psychology
43
NurHafidz, Muhammad Meidy, and 馬哈曼. "An Optimal Joint UAV and Ground Vehicle Path Planning Problem for Area Coverage with Energy Consideration." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/4ukecq.
Full textAbstract:
碩士國立成功大學
工業與資訊管理學系
107
The Unmanned Aerial Vehicles (UAVs) may be the only means by which to conduct coverage missions that search, monitor, or take photos from the air space over target ground areas that are too difficult to reach by ground manpower. Suppose we divided the air space into several virtual cells that cover all the target ground areas. Then, a scan mission on a target ground area can be done by a UAV flying over (i.e., covering) its corresponding virtual cell in air space for a specific period of time. In this research, we plan to route UAVs to cover all necessary virtual cells. Since UAVs have limited battery power, they can be carried by some mobile Ground Vehicles (GVs) and then be launched from and retrieved by GVs on some nodes in the ground road networks. This thesis investigates how to calculate optimal routes for both GVs and UAVs so that all the target ground areas can be scanned by UAVs within a minimum total time subject to the battery limitation of the UAVs. To model the combined operations by the UAVs and GVs, we use the coverage path planning (CPP) and two-echelon routing problems as our approaches. We propose two mathematical models based on integer programming techniques over a time-space network. We consider one GV with one UAV case ( ) and one GV with multiple UAVs case ( ). To the best of our knowledge, might arguably be the first mathematical programming model that can deal with routings for both GV and multiple UAVs at the same time. Our proposed model can calculate the detailed movement for both UAVs and GV, yet it is very time-consuming. To calculate good routings in shorter time, we also designed a greedy algorithm for the one GV with one UAV case, where a depth-first search mechanism is exploited to find a feasible UAV route in the time-pace network that covers all target areas within the time limit T. The computational experiments indicate our greedy algorithm calculates a good solution faster than the proposed integer programming model.
44
Xu, Shihong. "Replica placement algorithms for efficient internet content delivery." 2009. http://hdl.handle.net/2440/58083.
Full textAbstract:
This thesis covers three main issues in content delivery with a focus on placement algorithms of replica servers and replica contents. In a content delivery system, the location of replicas is very important as perceived by a quotation: Closer is better. However, considering the costs incurred by replication, it is a challenge to deploy replicas in a cost-effective manner. The objective of our work is to optimally select the location of replicas which includes sites for replica server deployment, servers for replica contents hosting, and en-route caches for object caching. Our solutions for corresponding applications are presented in three parts of the work, which makes significant contributions for designing scalable, reliable, and efficient systems for Internet content delivery. In the first part, we define the Fault-Tolerant Facility Allocation (FTFA) problem for the placement of replica servers, which relaxes the well known Fault-Tolerant Facility Location (FTFL) problem by allowing an integer (instead of binary) number of facilities per site. We show that the problem is NP-hard even for the metric version, where connection costs satisfy the triangle inequality. We propose two efficient algorithms for the metric FTFA problem with approximation factors 1.81 and 1.61 respectively, where the second algorithm is also shown to be (1.11,1.78)- and (1,2)-approximation through the proposed inverse dual fitting technique. The first bi-factor approximation result is further used to achieve a 1.52-approximation algorithm and the second one a 4-approximation algorithm for the metric Fault-Tolerant k-Facility Allocation problem, where an upper bound of facility number (i. e. k) applies. In the second part, we formulate the problem of QoS-aware content replication for parallel access in terms of combined download speed maximization, where each client has a given degree of parallel connections determined by its QoS requirement. The problem is further converted into the metric FTFL problem and we propose an approximation algorithm which is implemented in a distributed and asynchronous manner of communication. We show theoretically that the cost of our solution is no more than 2F* + RC*, where F* and C* are two components of any optimal solution while R is the maximum number of parallel connections. Numerical experiments show that the cost of our solutions is comparable (within 4% error) to the optimal solutions. In the third part, we establish mathematical formulation for the en-route web caching problem in a multi-server network that takes into account all requests (to any server) passing through the intermediate nodes on a request/response path. The problem is to cache the requested object optimally on the path so that the total system gain is maximized. We consider the unconstrained case and two QoS-constrained cases respectively, using efficient dynamic programming based methods. Simulation experiments show that our methods either yield a steady performance improvement (in the unconstrained case) or provide required QoS guarantees.http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1461921
Thesis (Ph.D.) - University of Adelaide, School of Computer Science, 2009
45
Chang, Hsi-Hsiang, and 張喜翔. "Application of Multi-objective Optimal Algorithm to the Capacitor Placement Problem in Distribution Systems." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/62028278197622239308.
Full textAbstract:
碩士國立中正大學
電機工程研究所
92
A proper capacitor placement technique can effectively enhance the power quality. This work presents a new approach for solving the capacitor placement problem and helps the dispatcher making policy decisions. To obtain the essential states of system conditions, such as bus voltages and feeder currents, this study utilizes the power flow analyses which are evaluated by a set of recursive equations to calculate the feeder currents and bus voltages. Then, a multi-objective algorithm is presented to solve the capacitor placement problem in a distribution system. These objective functions in the considered problem are modeled with fuzzy sets to express their uncertain and subjective characteristics. Moreover, an interactive trade-off method based on the simulated annealing and the ε-constrained technique is presented for the optimal capacitor allocation problem. To the most concerns of the system planner, the objective formulation involves cost investment, power loss, deviation of the bus voltage, and feeder’s current. With the interactive steps, the planner can provide his or her preference on each objective or requirement of system security and service quality to resolve the multi-objective optimization problem and reach a non-inferiority solution. To verify the effectiveness of the proposed method, the method is applied to a Taipower distribution system with the voltage level of 11.4KV and 32 buses. Computation results have shown that the proposed method is suitable for applications to the capacitor placement problem.
46
Xu, Shihong. "Replica placement algorithms for efficient internet content delivery." Thesis, 2009. http://hdl.handle.net/2440/58083.
Full textAbstract:
This thesis covers three main issues in content delivery with a focus on placement algorithms
of replica servers and replica contents. In a content delivery system, the location
of replicas is very important as perceived by a quotation: Closer is better. However,
considering the costs incurred by replication, it is a challenge to deploy replicas in a
cost-effective manner. The objective of our work is to optimally select the location of
replicas which includes sites for replica server deployment, servers for replica contents
hosting, and en-route caches for object caching. Our solutions for corresponding applications
are presented in three parts of the work, which makes significant contributions
for designing scalable, reliable, and efficient systems for Internet content delivery.
In the first part, we define the Fault-Tolerant Facility Allocation (FTFA) problem for
the placement of replica servers, which relaxes the well known Fault-Tolerant Facility
Location (FTFL) problem by allowing an integer (instead of binary) number of facilities
per site. We show that the problem is NP-hard even for the metric version, where
connection costs satisfy the triangle inequality. We propose two efficient algorithms
for the metric FTFA problem with approximation factors 1.81 and 1.61 respectively,
where the second algorithm is also shown to be (1.11,1.78)- and (1,2)-approximation
through the proposed inverse dual fitting technique. The first bi-factor approximation
result is further used to achieve a 1.52-approximation algorithm and the second one a
4-approximation algorithm for the metric Fault-Tolerant k-Facility Allocation problem,
where an upper bound of facility number (i. e. k) applies.
In the second part, we formulate the problem of QoS-aware content replication for
parallel access in terms of combined download speed maximization, where each client
has a given degree of parallel connections determined by its QoS requirement. The problem is further converted into the metric FTFL problem and we propose an approximation
algorithm which is implemented in a distributed and asynchronous manner of
communication. We show theoretically that the cost of our solution is no more than
2F* + RC*, where F* and C* are two components of any optimal solution while R
is the maximum number of parallel connections. Numerical experiments show that the
cost of our solutions is comparable (within 4% error) to the optimal solutions.
In the third part, we establish mathematical formulation for the en-route web caching
problem in a multi-server network that takes into account all requests (to any server)
passing through the intermediate nodes on a request/response path. The problem is to
cache the requested object optimally on the path so that the total system gain is maximized.
We consider the unconstrained case and two QoS-constrained cases respectively,
using efficient dynamic programming based methods. Simulation experiments show that
our methods either yield a steady performance improvement (in the unconstrained case)
or provide required QoS guarantees.Thesis (Ph.D.) - University of Adelaide, School of Computer Science, 2009
47
Shehab, Samer. "Control of a PWA system cascaded with a nonlinear system : an application to a UAV path following problem." Thesis, 2006. http://spectrum.library.concordia.ca/8967/1/MR14313.pdf.
Full textAbstract:
Over the past few decades, there has been a significant need for the use of Uninhabited Aerial Vehicles (UAVs) in both civilian and military applications. Nowadays, UAVs are becoming increasingly popular to perform hard missions that include surveillance, sensing (of, for example, chemical agents), acquiring weather data, and reconnaissance over oceanic and remote areas. Motivated by such importance of UAV missions, this thesis presents a new control methodology applied to a UAV path following problem in the longitudinal plane. This control methodology takes into account the actuator dynamics that is used to deflect the elevator of the UAV. In particular, it considers a model of the Coulomb friction that exists in the dynamics of the actuator. For controller design purposes, the overall dynamics of the UAV are divided into two sets of dynamics that are in cascade connection. One set of dynamics describes the steering motion of the UAV and another set describes the translational motion of the UAV, where both motions are in the longitudinal plane. Each set is treated separately in the controller design. A piecewise-affine state feedback controller is designed for the dynamics of the steering subsystem of the UAV and a nonlinear controller is designed for the dynamics of the translational velocity subsystem of the UAV. Stability of the novel cascade interconnection of the two subsystems is investigated. Simulation results show the effectiveness of the proposed control methodology.
48
HSU, HUNG-MING, and 許宏銘. "A Study of Multi-Objective Genetic Algorithm Applying on Routing Problem of Heterogeneous UAV Fleet with Adjustable View Angle." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/vw6fkt.
Full textAbstract:
碩士中華大學
資訊工程學系
105
Unmanned Aerial Vehicle (UAV) with the characteristic of low cost and high mobility. Compared to flying traditional aircraft, the requirements of landing UAV site is low, the skill of UAV operation is ease, and UAV is capable to avoid the risk of human accident. Therefore, it is very suitable for alternative personnel to carry out a variety kinds of high-risk missions. Among these missions, aerial photography is one of the most popular application of unmanned aerial vehicles. In this paper, we investigated the uses of heterogeneous UAVs in aerial photography mission within a limited area. In the literature, numerous approaches have been proposed in UAV path planning, such as adding UAV flight parameter control, single or multiple UAVs flight path planning ... and so on. However, none of them discussed heterogeneous UAVs. In this paper, the concept of flying path is not equivalent to the cruise path is proposed. The objective of UAV path planning should meet the requirement of aerial photography mission while optimizes the mission costs. Therefore, we investigated the heterogeneous UAVs with adjustable image angle in aerial photography mission. A multiobjective optimization problem is formulated, considering the coverage of UAV camera, flight distance of UAVs, energy consumption, and the configuration of heterogeneous UAVs. In this paper, we proposed a multi-objective evolutionary approach to solve the investigated problem. From the experimental results, the proposed approach can effectively obtain multiple non-dominated solutions. The solutions also shows that the decoded routes of UAVs path is very similar to the appearance of the demand model.
49
Wei-TeHo and 何威德. "The Impact of Private Placement of Equity on Operating Performance and the Influence of Central Agency Problem and Corporate Governance." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/83830962392873182190.
Full textAbstract:
博士國立成功大學
會計學系碩博士班
100
This study mainly examines the impact of private placement of equity on the operating performance by considering the influence of central agency problem and corporate governance. We find that private equity offering firms had better improvement in operating performance than seasoned equity offering firms subsequent to the year of issue. Among private placement investors, insiders are familiar with the firm and are in a better position to resolve asymmetric information, so they can help firm improve the operating performance. We also find that private equity offering firms issuing at premium and discount price had better post-placement operating performance, which results from that the private equity discount may inform better operating performance in the future and the premium may reflect better future sales growing opportunities. Furthermore, we find that the firms with losses prior to equity issue have significantly improved the operating performance, but the ones with profits do not. In addition, when the private placement investors are insiders, firms have better post-placement operating performance regardless of firms issuing at premiums, issuing at discounts, or with financial distress prior to the issue, but not for the case when firms with profits prior to the private placement. About the effect of central agency problem, board of structure and external monitoring mechanism, we find the incentive effect can improve the operating performance of firms of all private placement, issuing at premiums, issuing at discounts, with financial distress prior to the issue, or the insider investor involving with financial distress prior to the issue, but for the passive investor the operating performance decline due to the deviation of control from cash-flow right by controlling family. The results also show that the operating performance of private equity offering firms issuing at discount decline due to the degree of collateralization of the stock held by the controlling family. In addition, the increase appointment of independent directors improve the operating performance of the firms of all private placement, insider investor, or insider investor involving with profits prior to the issue. We also find the Big 4 CPA firms can improve the operating performance of the firms of all private placement, insider investor, or insider investor having profits prior to the issue. Additional test shows that insiders cannot reduce shareholder wealth even if the price discount is over 20% per share for privately placed equity. Our results support the regulations about the limitations of insiders participating in the use of the private placement to issue for a public firm with a net profit and no accumulated deficit for the most recent fiscal year, and emphasize the importance of corporate governance.
50
Lin, Yi-Ling, and 林奕伶. "A Novel Simulated Annealing Algorithm for the Mesh Router Node Placement Problem with Service Priority Constraint in Wireless Mesh Networks." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/09034354172285300812.
Full textAbstract:
碩士國立交通大學
工業工程與管理系所
101
The quality of service (QoS) performance of wireless mesh networks (WMNs) is measured by the topology connectivity as well as the client coverage, both of which are related to the problem of router node placement (RNP), in which each mesh client is served as equal. In practice, however, mesh clients with different payments for the network services should be provided by different qualities of network connectivity and QoS. As a result, to respond to the practical requirements, this paper considers a more complicated RNP problem with service priority constraint in WMNs (WMN-RNP) in which each mesh client is additionally associated with a priority value, in which the mesh clients with smaller priority values are served with higher priority. The WMN-RNP problem with service priority constraint inherited from the original RNP problem is computationally intractable in general, and hence this paper further proposes a novel simulated annealing (SA) approach that adds momentum terms to search resolutions more effectively. Momentum terms can be used to improve speed and accuracy of the original annealing schedulers, and to prevent extreme changes in values of acceptance probability function. Finally, this paper simulates the proposed novel SA approach for different-size instances, and discusses the effect of different parameters and annealing schedulers.