Дисертації з теми "Repeated problems"
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1
Etheve, Marc. "Solving repeated optimization problems by Machine Learning." Thesis, Paris, HESAM, 2021. http://www.theses.fr/2021HESAC040.
Анотація:
Cette thèse a pour but d’utiliser des techniques d’apprentissage automatique pour larésolution de problèmes linéaires en nombres entiers issus de données stochastiques. Plutôt que de lesrésoudre indépendamment, nous proposons de tirer profit des similarités entre instances en apprenantdifférentes stratégies au sein d’un algorithme de Branch and Bound (B&B).L’axe principal développé est l’utilisation d’apprentissage par renforcement pour découvrir des stratégiesminimisant la taille des arbres de B&B. Afin de s’adapter `a l’environnement induit par l’algorithmede B&B, nous définissons un nouveau type de transitions au sein de processus de décision markoviens,basées sur la structure d’arbre binaire. Par ailleurs, nous étudions différents modèles de coûts et prouvonsl’optimalité du modèle de coût unitaire sous les transitions classiques et binaires, dans l’apprentissagedes stratégies de branchement et de sélection de noeud. Pour autant, les expérimentations menéessuggèrent qu’il peut -être préfèrable de biaiser le modèle de coût afin d’améliorer la stabilité du processusd’apprentissage. En ce qui concerne la stratégie de sélection de noeud, nous démontrons l’optimalitéd’une stratégie explicitement définie, qui peut -être apprise plus efficacement de manière supervisée.Par ailleurs, nous proposons d’exploiter la structure des problèmes étudiés. Nous étudions pour cela unestratégie de décomposition-coordination, une heuristique de branchement basée sur une représentationpar graphe d’un noeud de l’arbre de B&B et enfin l’apprentissage de perturbations de la fonction objectifThis thesis aims at using machine learning techniques in the context of Mixed Integer LinearProgramming instances generated by stochastic data. Rather than solve these instances independentlyusing the Branch and Bound algorithm (B&B), we propose to leverage the similarities between instancesby learning inner strategies of this algorithm, such as node selection and branching.The main approach developed in this work is to use reinforcement learning to discover by trials-and-errorsstrategies which minimize the B&B tree size. To properly adapt to the B&B environment, we definea new kind of tree-based transitions, and elaborate on different cost models in the correspondingMarkov Decision Processes. We prove the optimality of the unitary cost model under both classical andtree-based transitions, either for branching or node selection. However, we experimentally show that itmay be beneficial to bias the cost so as to improve the learning stability. Regarding node selection, weformally exhibit an optimal strategy which can be more efficiently learnt directly by supervised learning.In addition, we propose to exploit the structure of the studied problems. To this end, we propose adecomposition-coordination methodology, a branching heuristic based on a graph representation of aB&B node and finally an approach for learning to disrupt the objective function
2
Burkov, Andriy. "Leveraging Repeated Games for Solving Complex Multiagent Decision Problems." Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28028/28028.pdf.
Анотація:
Prendre de bonnes décisions
dans des environnements multiagents est une tâche difficile dans la
mesure où la présence de plusieurs décideurs implique des conflits
d'intérêts, un manque de coordination, et une multiplicité de
décisions possibles. Si de plus, les décideurs interagissent
successivement à travers le temps, ils doivent non seulement décider
ce qu'il faut faire actuellement, mais aussi comment leurs décisions
actuelles peuvent affecter le comportement des autres dans le futur.
La théorie des jeux est un outil mathématique qui vise à modéliser
ce type d'interactions via des jeux stratégiques à plusieurs
joueurs. Des lors, les problèmes de décision multiagent sont souvent
étudiés en utilisant la théorie des jeux. Dans ce contexte, et si on
se restreint aux jeux dynamiques, les problèmes de décision
multiagent complexes peuvent être approchés de façon algorithmique.
La contribution de cette thèse est triple. Premièrement, elle
contribue à un cadre algorithmique pour la planification distribuée
dans les jeux dynamiques non-coopératifs. La multiplicité des plans
possibles est à l'origine de graves complications pour toute
approche de planification. Nous proposons une nouvelle approche
basée sur la notion d'apprentissage dans les jeux répétés. Une telle
approche permet de surmonter lesdites complications par le biais de
la communication entre les joueurs.
Nous proposons ensuite un algorithme d'apprentissage pour les jeux
répétés en ``self-play''. Notre algorithme permet aux joueurs de
converger, dans les jeux répétés initialement inconnus, vers un
comportement conjoint optimal dans un certain sens bien défini, et
ce, sans aucune communication entre les joueurs.
Finalement, nous proposons une famille d'algorithmes de résolution
approximative des jeux dynamiques et d'extraction des stratégies des
joueurs. Dans ce contexte, nous proposons tout d'abord une méthode
pour calculer un sous-ensemble non vide des équilibres approximatifs
parfaits en sous-jeu dans les jeux répétés. Nous montrons ensuite
comment nous pouvons étendre cette méthode pour approximer tous les
équilibres parfaits en sous-jeu dans les jeux répétés, et aussi
résoudre des jeux dynamiques plus complexes.Making good decisions in multiagent environments is a hard problem in the sense that the presence of several decision makers implies conflicts of interests, a lack of coordination, and a multiplicity of possible decisions. If, then, the same decision makers interact continuously through time, they have to decide not only what to do in the present, but also how their present decisions may affect the behavior of the others in the future. Game theory is a mathematical tool that aims to model such interactions as strategic games of multiple players. Therefore, multiagent decision problems are often studied using game theory. In this context, and being restricted to dynamic games, complex multiagent decision problems can be algorithmically approached. The contribution of this thesis is three-fold. First, this thesis contributes an algorithmic framework for distributed planning in non-cooperative dynamic games. The multiplicity of possible plans is a matter of serious complications for any planning approach. We propose a novel approach based on the concept of learning in repeated games. Our approach permits overcoming the aforementioned complications by means of communication between players. We then propose a learning algorithm for repeated game self-play. Our algorithm allows players to converge, in an initially unknown repeated game, to a joint behavior optimal in a certain, well-defined sense, without communication between players. Finally, we propose a family of algorithms for approximately solving dynamic games, and for extracting equilibrium strategy profiles. In this context, we first propose a method to compute a nonempty subset of approximate subgame-perfect equilibria in repeated games. We then demonstrate how to extend this method for approximating all subgame-perfect equilibria in repeated games, and also for solving more complex dynamic games.
3
Yousaf, Muhammad. "Repeated updating as a solution tool for linear least squares problems." Thesis, University of Essex, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528864.
4
Vadasy, Patricia F. "Routes to comprehension for second-graders with reading problems : one-to-one tutoring in repeated reading versus comprehension strategy instruction /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/7519.
5
Brown, Leonard Dale. "The effects of alternative reading and math strategy treatments on word problem-solving." Oxford, Ohio : Miami University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1272846865.
6
Wittchen, Hans-Ulrich, Silke Behrendt, Michael Höfler, Axel Perkonigg, Jürgen Rehm, Roselind Lieb, and Katja Beesdo. "A typology of cannabis-related problems among individuals with repeated illegal drug use in the first three decades of life: Evidence for heterogeneity and different treatment needs." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-111264.
Анотація:
Background: Cannabis use (CU) and disorders (CUD) are highly prevalent among adolescents and young adults. We aim to identify clinically meaningful latent classes of users of cannabis and other illegal substances with distinct problem profiles.
Methods: N= 3021 community subjects aged 14–24 at baseline were followed-up over a period ranging up to 10 years. Substance use (SU) and disorders (SUD) were assessed with the DSM-IV/M-CIDI. Latent class analysis (LCA) was conducted with a subset of N= 1089 subjects with repeated illegal SU. The variables entered in the LCA were CU-related problems, CUD, other SUD, and other mental disorders.
Results: Four latent classes were identified: “Unproblematic CU” (class 1: 59.2%), “Primary alcohol use disorders” (class 2: 14.4%), “Delinquent cannabis/alcohol DSM-IV-abuse” (class 3: 17.9%), “CUD with multiple problems” (class 4: 8.5%). Range and level of CU-related problems were highest in classes 3 and 4. Comorbidity with other mental disorders was highest in classes 2 and 4. The probability of alcohol disorders and unmet treatment needs was considerable in classes 2–4.
Conclusion: While the majority of subjects with repeated illegal SU did not experience notable problems over the 10-year period, a large minority (40.8%) experienced problematic outcomes, distinguished by clinically meaningful profiles. The data underline the need for specifically tailored interventions for adolescents with problematic CU and highlight the potentially important role of alcohol and other mental disorders.
7
Wittchen, Hans-Ulrich, Silke Behrendt, Michael Höfler, Axel Perkonigg, Jürgen Rehm, Roselind Lieb, and Katja Beesdo. "A typology of cannabis-related problems among individuals with repeated illegal drug use in the first three decades of life: Evidence for heterogeneity and different treatment needs." Technische Universität Dresden, 2009. https://tud.qucosa.de/id/qucosa%3A26837.
Анотація:
Background: Cannabis use (CU) and disorders (CUD) are highly prevalent among adolescents and young adults. We aim to identify clinically meaningful latent classes of users of cannabis and other illegal substances with distinct problem profiles.
Methods: N= 3021 community subjects aged 14–24 at baseline were followed-up over a period ranging up to 10 years. Substance use (SU) and disorders (SUD) were assessed with the DSM-IV/M-CIDI. Latent class analysis (LCA) was conducted with a subset of N= 1089 subjects with repeated illegal SU. The variables entered in the LCA were CU-related problems, CUD, other SUD, and other mental disorders.
Results: Four latent classes were identified: “Unproblematic CU” (class 1: 59.2%), “Primary alcohol use disorders” (class 2: 14.4%), “Delinquent cannabis/alcohol DSM-IV-abuse” (class 3: 17.9%), “CUD with multiple problems” (class 4: 8.5%). Range and level of CU-related problems were highest in classes 3 and 4. Comorbidity with other mental disorders was highest in classes 2 and 4. The probability of alcohol disorders and unmet treatment needs was considerable in classes 2–4.
Conclusion: While the majority of subjects with repeated illegal SU did not experience notable problems over the 10-year period, a large minority (40.8%) experienced problematic outcomes, distinguished by clinically meaningful profiles. The data underline the need for specifically tailored interventions for adolescents with problematic CU and highlight the potentially important role of alcohol and other mental disorders.
8
Arner, Erik. "Solving repeat problems in shotgun sequencing /." Stockholm, 2006. http://diss.kib.ki.se/2006/91-7140-996-3/.
9
Ndikintum, Nfii Kangong. "A Special Inference Problem in Repeated Measures Design with Applications to Pulse Oximetry." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1177418766.
10
Brown, Leonard Dale. "The effects of alternative reading and math strategy treatments on word problem-solving." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1272846865.
11
Tinnert, Agneta. "Den upprepade aborten - problem för vem?" Thesis, Malmö högskola, Fakulteten för hälsa och samhälle (HS), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-26129.
Анотація:
The aim of this study was from the beginning to examine why a woman who has made an abortion comes back for another one. Why does the risk taking continue, despite the fact that abortion is perceived as emotionally hard? How can this be understood?This study consists of a literature review and semi-structured interviews. I wanted to interview women who had made a decision to have a repeated abortion, but it was difficult to get that kind of interviews. I then decided to interview the staff who meets women searching for an abortion to have their attitudes and experiences of women coming back for another abortion. It is a qualitative research. I have tried to understand the phenomena "repeated abortion" by using theories based in social constructionism and gender perspectives. My conclusion is that the repeated abortion may not be a problem for the woman but for the care in which the abortion is performed.
12
Tillyer, Marie Skubak. "Getting a Handle on Street Violence: Using Environmental Criminology to Understand and Prevent Repeat Offender Problems." Cincinnati, Ohio : University of Cincinnati, 2008. http://rave.ohiolink.edu/etdc/view.cgi?acc_num=ucin1225834818.
Анотація:
Thesis (Ph.D.)--University of Cincinnati, 2008.Advisor: John Eck. Title from electronic thesis title page (viewed Feb.16, 2009). Keywords: environmental criminology; handlers; routine activities theory. Includes abstract. Includes bibliographical references.
13
Morales, Zoe A. "Using a Repeated Measures ANOVA Design to Analyze the Effect Writing in Mathematics Has on the Mathematics Achievement of Third Grade English Language Learners and English Speakers." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2719.
Анотація:
The gap that exists between English language learners and English speaking students’ achievement in mathematics continues to grow. Moreover, students are now required to show evidence of their mathematics knowledge through writing in standardized assessments and class assignments.
The purpose of this study was to analyze students’ writing in mathematics and the metacognitive behaviors they portrayed through their writing as they solved mathematics problems. The instruments included a pretest, two biweekly tests, and a posttest. The writing instruction encompassed students learning to solve problems by using Polya’s four phases of problem solving which was completed in 12 sessions over a period of 6 weeks. Garofalo and Lester’s framework which renamed Polya’s phases into orientation, organization, execution, and verification, was used to look at the metacognitive behaviors students used. The participants included 67 students enrolled in four third grade classes, who were English language learners and English speakers.
This research followed a quasi-experimental design, with a treatment group and a control group. A one-way repeated ANOVA was used to analyze the data. The findings showed no significant difference between the mathematics achievement scores of treatment and control. However, growth trends in achievement scores revealed that the treatment group scores were increasing faster than the control group scores across the four tests during the 6-week study. Moreover, significant differences were found between the treatment and the control groups when the problem solving with metacognitive behaviors scores were analyzed. Descriptive statistics showed the frequency of occurrence of each of the problem solving phases increased steadily across the four tests for the students in the treatment group. During the posttest, 100% of treatment group students wrote about metacognitive behaviors they used during the orientation and organization phases, 91.4% wrote about their metacognition for executing the solution, and 80% wrote about the verification process they followed.
These findings are useful to education professionals who are interested in creating programs for teaching mathematics at the elementary level that include effective problem solving practices. This evidence-based method may be adopted in school districts with large populations of ELLs in order to assist these students when solving problems in mathematics.
14
Archibald, Margaret Lyn. "Combinatorial problems related to sequences with repeated entries." Thesis, 2006. http://hdl.handle.net/10539/1732.
Анотація:
Student Number : 9708525G -
PhD thesis -
School of Mathematics -
Faculty of ScienceSequences of numbers have important applications in the field of Computer Science. As a result they have become increasingly regarded in Mathematics, since analysis can be instrumental in investigating algorithms. Three concepts are discussed in this thesis, all of which are concerned with ‘words’ or ‘sequences’ of natural numbers where repeated letters are allowed: • The number of distinct values in a sequence with geometric distri- bution In Part I, a sample which is geometrically distributed is considered, with the objective of counting how many different letters occur at least once in the sample. It is concluded that the number of distinct letters grows like log n as n → ∞. This is then generalised to the question of how many letters occur at least b times in a word. • The position of the maximum (and/or minimum) in a sequence with geometric distribution Part II involves many variations on the central theme which addresses the question: “What is the probability that the maximum in a geometrically distributed sample occurs in the first d letters of a word of length n?” (assuming d ≤ n). Initially, d is considered fixed, but in later chapters d is allowed to grow with n. It is found that for 1 ≤ d = o(n), the results are the same as when d is fixed. • The average depth of a key in a binary search tree formed from a sequence with repeated entries Lastly, in Part III, random sequences are examined where repeated letters are allowed. First, the average left-going depth of the first one is found, and later the right-going path to the first r if the alphabet is {1, . . . , r} is examined. The final chapter uses a merge (or ‘shuffle’) operator to obtain the average depth of an arbitrary node, which can be expressed in terms of the left-going and right-going depths.
15
Siebecker, Amanda B. "Victimization and internalizing problems examining the experience of repeated bullying, anxiety, and depression /." 2009. http://proquest.umi.com/pqdweb?did=1933020051&sid=4&Fmt=2&clientId=14215&RQT=309&VName=PQD.
Анотація:
Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009.Title from title screen (site viewed February 25, 2010). PDF text: 140 p. : ill. ; 1 Mb. UMI publication number: AAT 3386561. Includes bibliographical references. Also available in microfilm and microfiche formats.
16
Kao, Shih-Lin, and 高世霖. "A Repeated Agent Gaming and Genetic Algorithm Hybrid Method for Factory Location Setting and Factory/Supplier Selection Problems." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/10970962898628168385.
Анотація:
碩士國立臺灣大學
工業工程學研究所
94
This paper presents two supply chain design problems: 1) a factory location setting and factory selection problem, and 2) a factory location setting and factory/supplier selection problem. The first problem involves a number of location fixed retailers choosing a factory to supply their demands and a number of factories whose locations are to be determined. The goal is to minimize the sum of transportation and manufacturing costs. In the second problem, the raw material procurement cost is additively added, since a number of material suppliers are involved and each factory needs to select one supplier to provide the raw material. Economic factors are considered in the cost evaluations. Therefore, the partner selections (factory selection for retailers and material supplier selection for factories) will influence the manufacturing and procurement costs significantly. To solve these problems, a repeated agent gaming and genetic algorithm hybrid method (AGGAHM) is proposed. The AGGAHM uses a mutual frozen mechanism to consecutively enable and disable the evolutions of agent gaming and genetic computation. Based on this proposed method, a prototype system, namely agent gaming/genetic algorithm hybrid optimization system (AGGAHOS) is developed to test several postulated numerical examples. Computation results of the AGGAHM are compared with those from methods of genetic algorithms and mutual frozen genetic algorithms. Results show that AGGAHM outperforms the methods solely using genetic algorithms. In addition, several supply chain design scenarios are established to verify the solutions against the practical applications.
17
Decrouppe, Andre. "Optimal Incentives to Foster Cross Selling: An Economic Analysis." Thesis, 2014. http://epub.wu.ac.at/4486/1/Dissertation_Andre_Decrouppe_Learn@WU.pdf.
Анотація:
Cross selling is the practice of selling additional products to an existing
customer. It has the potential to boost revenues and can be beneficial for
both the company and the customer. For many multi-divisional companies
with product or service oriented organizational structures the attempt to
realize the benefits of cross selling generates incentive problems. In this
thesis, three problems spread over three business levels are identified.
Firstly, management needs to (financially) motivate business units in
fostering their cross selling efforts. Secondly, in order to make cross
selling happen, business units need to cooperate and to exchange
product-related information. Finally, in order to increase their short-term
benefits business units might act opportunistically by selling products or
services of other business units without paying attention to adding value
for their customers. These incentive problems are theoretically examined
by applying principal-agent theory and the theory of repeated games. Our
findings suggest that an optimized incentive structure is required to make
both the business units and the management better off. The thesis also
analyses the circumstances and necessary prerequisites under which cross
selling initiatives are beneficial for all involved parties. Apart from that
cross selling sometimes may turn out to be non-beneficial. In addition to
the elaborations above, risks and hazards of cross selling are presented in
detail and applied for the extension of the underlying model. Bottom line,
the work underlines that cross selling is to be realized holistically to
ensure durable success. (author's abstract)
18
Venne, Danielle M. "Impacts of Casino Gambling Availability in Plainville, Massachusetts: A Repeated Cross-sectional Analysis." 2018. https://scholarworks.umass.edu/masters_theses_2/673.
Анотація:
The impacts of the introduction of casino gambling in Plainville, MA and surrounding communities are of interest in developing informed policy. Problem gambling is a public health issue as associated harms include physical and mental illness, impaired relationships with one’s close social network, impacts on school or work, financial difficulties and illegal behavior. The results of surveys prior to and after the introduction of the casino were used to evaluate potential differences in the prevalence of at-risk and problem gambling, associations amongst health and gambling behavior covariates with at-risk and problem gambling status by year, and changes of covariate relationships with at-risk and problem gambling between years (2014 Total n = 1,090; 2016 Total n = 999; Total N = 2,089). No change in prevalence of at-risk and problem gambling was observed. A borderline significant higher rate in casino gambling between survey years was observed for at-risk and problem gamblers. Future research should aim to explore the influence of gambling availability on vulnerable subgroups of the population to create fully informed policy.
19
Sheng-Gang, Wu, and 伍學綱. "The inference of change-point problem in Multinomial Distribution for repeated measures." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/95206019312261562441.
20
Zhang, Wei, and 張瑋. "A Study of Repeated Push Problem and Improvement for HTTP/2 Server Push." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/v5gke9.
Анотація:
碩士國立高雄應用科技大學
資訊管理研究所碩士班
105
With the rapidly development and widely use of Internet technology, the design of higher speed and more secure Internet protocols has becoming a more and more important issue for practitioners and scholar. The new network protocol: HTTP/2, which has been published in RFC7540 in May 2015, is now be expected by more and more people to provide better performance than HTTP/1.1 in multiple aspects, i.e. the header compression and server push in reducing the web page loading time. Although HTTP/2 server push can make the web page load faster, this new update function may cause the server to push the same resources repeatedly, or lead to a slower transmission of push resources, resulting in incorrect judgements of lost resources and the corresponding duplicate resource requests. Accordingly, this research aims to use the session mechanism to prevent the problem of repeated push of same resources when a client is already cached resources. Queue and stack are further used to avoid unnecessary transmission wastes of resources and streams that may occur when client browser incorrectly interpret servers’ responses of index.html file as missing file resource under the circumstances of some network delay or slower network speed.
21
Curwen, Tracey. "Differentiating children with and without a history of repeated problematic sexual behaviours following adult reprimand /." 2007. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=510567&T=F.
22
von, Lüpke Nikolas. "Approaches for the optimisation of double sampling for stratification in repeated forest inventories." Doctoral thesis, 2013. http://hdl.handle.net/11858/00-1735-0000-001E-F78E-8.
Анотація:
Die zweiphasige Stichprobe zur Stratifizierung ist ein effizientes Inventurverfahren, das seine Praxistauglichkeit in verschiedenen Waldinventuren unter Beweis stellen konnte. Dennoch sind weitere Effizienzsteigerungen wünschenswert. In der vorliegenden Arbeit werden verschiedene Ansätze die Effektivität dieses Verfahrens zu steigern separat vorgestellt, in Fallstudien mit Daten der Niedersächsischen Betriebsinventur getestet und diskutiert.
Der erste Ansatz (Kapitel 2) beschäftigt sich mit der Anwendung der zweiphasigen Stichprobe zur Stratifizierung in Wiederholungsinventuren. In einem Zusammengesetzten Schätzer werden Daten eines aktuellen mit Simulationsergebnissen des vorhergehenden Inventurdurchgangs kombiniert. Dabei kann der Stichprobenumfang der aktuellen Inventur verringert werden, während die Daten aller Inventurpunkte des vorherigen Durchgangs für Simulationen genutzt werden. Zwar kann ein solcher Schätzer konstruiert werden, jedoch lässt die Fallstudie darauf schließen, dass keine, oder zumindest keine ausreichende, Effizienzsteigerung erzielt werden kann. Erklärt werden kann dies durch die großen Unterschiede zwischen den aktuellen Inventurergebnissen aus den reduzierten Inventuren und den prognostizierten Volumina aus den Simulationen. Eine Erhöhung der Effizienz dieses Verfahrens könnte nur durch Weiterentwicklungen der Waldwachstumsmodelle möglich werden.
In Wiederholungsinventuren kann jedoch eine höhere Effizienzsteigerung mit einem dreiphasigen Verfahren erreicht werden, das die zweiphasige Stichprobe mit der zwei\-phasigen Regressionsstichprobe kombiniert (Kapitel 3). Mittelwert- und Varianzschätzer, die auf dem sogenannten infinite population approach in der ersten Phase beruhen, werden präsentiert. Genutzt werden dabei die Korrelationen zwischen den aktuellen Inventurergebnissen und den Wachstumssimulationen auf der Basis des vorherigen Inventurdurchgangs. Statt der Simulationsergebnisse können auch einfach die Ergebnisse des vorherigen Inventurdurchgangs zur Berechnung der Korrelationen genutzt werden. Allerdings führt die Nutzung der Simulationsergebnisse als Regressor in den meisten Fällen zu besseren Ergebnissen. Bei verringertem Stichprobenumfang der Folgeinventur und damit einhergehendem Präzisionsverlust, ist die Effizienz des dreiphasigen Verfahrens höher als die des klassischen zweiphasigen Verfahrens. Die Nutzung der Vorinventur in Form eines stratenweisen Regressionsschätzers hat sich damit als erfolgreich und gegenüber dem zusammengesetzten Schätzer als deutlich überlegen gezeigt.
Als weiterer Ansatz wird die Erweiterung der zweisphasigen Stichprobe zur Stratifizierung um eine geclusterte Unterstichprobe zu einem dreiphasigen Design vorgestellt (Kapitel 4). Sowohl für den Ratio-to-Size- als auch für den unverzerrten Ansatz werden entsprechende Mittelwert- und Varianzschätzer präsentiert. Verglichen mit dem zweiphasigen Verfahren, führt dieses dreiphasige Design in der Fallstudie zu keiner Effizienzsteigerung. Gründe hierfür können in der vergleichsweise kleinen Größe der Forstämter und der hohen Stichprobendichte der Niedersächsischen Betriebsinventur gesehen werden. Sinnvolle Anwendungen dieses Verfahrens sind aber möglicherweise unter anderen Erschließungsbedingungen in Großgebieten denkbar.
In einer weiteren Fallstudie wird versucht existierende Probepunkte in Clustern von homogener Größe zusammenzufassen (Kapitel 5). Eine solche Zusammenfassung soll der Optimierung der Wegzeiten bei der Aufnahme von Inventurpunkten dienen. Dazu werden sieben verschiedene Methoden getestet und deren Ergebnisse miteinander verglichen. Durch einen Vergleich mit optimierten Richtwert-Lösungen wird zudem die Qualität dieser Lösungen evaluiert. Es zeigt sich, dass drei Algorithmen des Vehicle Routing Problems gut dazu geeignet sind, Cluster von homogener Größe zu erstellen. Nicht empfohlen werden kann dagegen die Verwendung von drei anderen Cluster-Algorithmen, sowie die Nutzung von Bewirtschaftungseinheiten als Cluster, da diese Methoden zu Clustern von sehr heterogener Größe führen.
23
Bonneville-Hébert, Ariane. "Analyse de la fertilité des vaches laitières Holstein «Repeat Breeder»." Thèse, 2009. http://hdl.handle.net/1866/3956.
Анотація:
L’importance de la problématique des vaches laitières non gestantes avec multiples inséminations (› 3) communément appelées « Repeat Breeder » (RB), au Québec, repose sur deux facteurs: son incidence et son impact économique. Actuellement, l’incidence du syndrome RB au Québec est de ± 25% (Rapport annuel, juin 2008, www.dsahr.ca). Les pertes monétaires associées à ce problème proviennent des frais vétérinaires et d’insémination, de la diminution de productivité ainsi que des pertes en lien avec la réforme involontaire. Afin d’avoir de meilleures connaissances sur ce syndrome, nous devons connaître les facteurs de risques généraux impliqués et ensuite explorer la condition individuelle de ces vaches problèmes.
Dans la première partie de ce mémoire, une banque de données informatisées répertoriant 418 383 lactations fut analysée. L’objectif de ce projet de recherche était d’évaluer l’impact des problèmes reproducteurs post-partum et l’effet du nombre de lactations comme facteurs de risques de la vache Repeat Breeder. L’analyse a permis d’établir la dystocie comme étant la condition ayant le plus de conséquences sur la fertilité future. D’autres facteurs de risques à savoir le nombre de lactations influencent le pronostic reproducteur.
La deuxième partie de ce mémoire consistait à explorer, à l’aide d’outils cliniques, la condition individuelle des vaches RB. Une étude cohorte fut menée sur des vaches Holstein en fin de période d’attente volontaire au jour 7 du cycle oestral. Les tests cliniques étudiés furent la vaginoscopie, l’examen transrectal, l’ultrasonographie du système reproducteur, la présence d’estérases leucocytaires, la bactériologie et la biochimie du liquide utérin, la cytologie endométriale et le profil de progestérone sérique. Les résultats de ces tests cliniques dévoilent que l’examen bactériologique du liquide utérin est révélateur du statut reproducteur futur.Two factors underlie the Repeat Breeder (RB) concerns in Quebec: its incidence and economic impact. Currently RB incidence in Quebec is of ± 25% (yearly Report, June 2008, www.dsahr.ca). Monetary losses related to the RB are the result of veterinary expenses and insemination, loss of productivity and the involuntary culling. In order to have a better knowledge of this syndrome, one must understand the general risk factors involved and then explore the individual condition of these problem cows. The goal of the first part of the project was to assess the impact of the postpartum reproductive problems and the effect of the lactation number as risk factors of the Repeat Breeder cow. A computerized data bank listing 418 383 lactations was analyzed. The analysis established dystocia as being the condition with the most consequences on future fertility. Other risk factors namely the number of lactations influence the reproductive prognosis as well. The second part of the research was to explore the individual condition of the RB using clinical tools. A cohort study was conducted on Holstein cows at the end of the voluntary waiting period on day 7 of the oestrous cycle. The clinical tests studied were vaginoscopy, trans-rectal examination, ultrasonography of the reproductive system, presence of leukocyte esterase, bacteriology and biochemistry of uterine fluid, endometrial cytology and serum progesterone profile. The results of these clinical tests reveal that the bacteriological analysis of uterine fluid is indicative of future reproductive status.
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Machisi, Eric. "Exploring solution strategies that can enhance the achievement of low-performing grade 12 learners in some mathematical aspects." Diss., 2013. http://hdl.handle.net/10500/13244.
Анотація:
The purpose of this study was to explore solution strategies that can enhance the achievement of low-performing Grade 12 learners in the following mathematical aspects: finding the general term of a quadratic sequence, factorising third degree polynomials, determining the centre and radius of a circle, and calculating the angle between two lines. A convenience sample of twenty-five low-performing Grade 12 learners from a secondary school in Capricorn District of Limpopo Province participated in the study which adopted a repeated-measures research design. Learners were exposed to multiple solution strategies and data were collected using achievement tests. Findings indicated significant differences in learners‟ average scores due to the solution strategies used. In determining the general term of a quadratic sequence, learners‟ scores were significantly higher when they used formula and the table method than with the method of residues and solving simultaneous equations. Synthetic division made learners to achieve better scores than long division and equating coefficients in factorising third degree polynomials. The use of formulae to find the centre and radius of a circle made learners to have better achievement scores than completing the square. In calculating the angle between two lines learners‟ scores were better using formula and the cosine rule than using theorems. It was concluded that exposing low-performing Grade 12 learners to multiple solution strategies would enhance their achievement in the mathematical aspects explored in the study. Some of the solution strategies that made learners to achieve better results were not in the prescribed mathematics textbooks. The study therefore recommends that mathematics teaching should not be textbook-driven and that low-performing Grade 12 learners should not be regarded as beyond redemption.Mathematics Education
M.Sc. (Mathematics, Science and Technology Education)