Дисертації з теми "Minimization of task time"

Магістерська дисертація: 110 с., 24 рис., 23 табл., 81 джерело, 1 додаток. Актуальність. На сьогодні стрімко зростає рівень складності об'єктів автоматизації підприємств різних сфер діяльності. Це пояснюється тим, що замовники висувають все більш специфічні вимоги до інформаційних систем для задоволення потреб підприємства. На цей час ІТ-галузь є однією з перспективніших сфер людської діяльності. Невід’ємною складовою якої є реалізація різних ІТ-проєктів від замовників з усього світу. Успішне виконання проєктів залежить від їх ефективного управління. Успішність проєкту залежить від низки показників, що визначають його сутність та впливають на стан проєкту протягом його життєвого циклу. Ця сукупність елементів проєкту по суті є об'єктами управління. Історія різноманітних підходів до питання управління проектами має вже п'ять тисяч років за своєю тривалістю, хоча перша згадка про управління проектами була наведена ще на початку 20 століття. Основоположниками управління проєктами можна назвати таких трьох вчених: Генрі Гант (1861–1919) — американський інженер, який у 1910 році створив та впровадив підхід календарного планування, де основою побудови діаграм стали горизонтальні елементи. Власне, його винахід такого планування пізніше стали називати діаграмою Ганта. Фредерік Уінслоу Тейлор (1856–1915) – американський інженер, математик та фізик, його роботи і досі використовують як прототипи сучасних різних інструментів, куди також входить ієрархічна структура його робіт. Анрі Файоль (1841–1925) — французький інженер, засновник головної класичної моделі управління проєктом. Став доволі відомим завдяки тому, що саме він описав 5 головних функцій управління (менеджменту), які, власне, і стали основою теорії управління проєктами. Теоретичні аспекти досліджень щодо управління проєктами містяться у працях таких українських та зарубіжних вчених, як, зокрема О.О. Кулінич, С.Д. Бушуєв, Ю.С. Грисюк, І.В. Кононенко, В.І. Максимова, В.Б. Силова, Є.К. Корноушенко, О.Г. Тімінський, В.І. Прангішвілі, Долорес Шервуд Стайгер, Ю.М. Теслі, Паула Мартін, Карел Тейт, Л.А. Заде, Деніз Колонна д’Істріа. У своїх працях вони висвітлювали питання розробки інформаційних технологій в проєктному менеджменті. Причиною актуальності ефективного процесу планування є необхідність збільшення людського потенціалу для вирішення унікальних задач. Доволі часто компанії реалізовують одночасно одразу декілька проектів, в яких задіяні одні й ті самі людські чи технічні ресурси. Автоматизація цього процесу може збільшити ефективність роботи компанії в цілому. На сьогоднішній день існує безліч прикладів підвищення ефективності, шляхом автоматизації монотонної ручної роботи. Зв'язок роботи з науковими програмами, планами, темами. Робота виконувалась на кафедрі автоматизованих систем обробки інформації та управління Національного технічного університету України «Київський політехнічний інститут ім. Ігоря Сікорського» в рамках теми «Ефективні методи розв’язання задач теорії розкладів» (№ ДР 0117U000919). Метою дослідження є підвищення ефективності виконання ІТ-проєктів в компанії, за рахунок створення інформаційної системи планування ресурсів ІТ-проектів, в основу якої покладені методи, що дозволяють мінімізувати час реалізації проєкту. Для досягнення поставленої мети необхідно виконати наступні завдання: − виконати аналітичний огляд та провести детальний аналіз існуючих систем планування ресурсів, управління проєктами, керування обмеженнями та ризиками у рамках проєкту, методів планування розкладів виконання завдань у межах ресурсних обмежень; − розробити алгоритми розв’язання задачі підтримки роботи системи планування ресурсів ІТ-проєктів; − дослідити ефективність розроблених алгоритмів; − розробити програмну реалізацію інформаційної системи планування ресурсів ІТ-проєктів; − виконати експериментальне дослідження розробленої інформаційної системи, методів розв’язання задачі та ефективність використаних алгоритмів. Об’єктом дослідження є процес управління ІТ-проєктами. Предметом дослідження є методи планування ресурсів ІТ-проектів. Методи дослідження. Для виконання поставлених завдань у роботі було використано методи: системного аналізу (при проектуванні інформаційної системи); теорії розкладів, дослідження операцій, теорії складності (при розробленні методів розв’язання задач розподілу ресурсів); комп’ютерного моделювання (при експериментальному дослідженні ефективності методів розв’язання задач розподілу ресурсів). Наукова новизна одержаних результатів полягає у побудові методу планування ресурсів, з урахуванням їх обмеженності, ризиків та аналізу; розробці та вдосконаленню алгоритмів розв’язання задачі за допомогою виконання експериментальних досліджень. Публікації. Матеріали роботи опубліковані у збірнику П’ятнадцятої міжнародної науково-практичної конференції МАТЕМАТИЧНЕ ТА ІМІТАЦІЙНЕ МОДЕЛЮВАННЯ СИСТЕМ (МОДС 2020), а також в матеріалах V всеукраїнської науково-практичної конференції молодих вчених та студентів «Інформаційні системи та технології управління» (ІСТУ-2020).
Master's dissertation: 110 pp., 24 figs., 23 tables, 81 sources, 1 appendix. Topicality. Today, the level of complexity of automation facilities of enterprises in various fields of activity is growing rapidly. This is due to the fact that customers are increasingly specific requirements for information systems to meet the needs of the enterprise. Currently, the IT industry is one of the most promising areas of human activity. An integral part of which is the implementation of various IT projects from customers around the world. Successful project implementation depends on their effective management. The success of a project directly depends on a number of indicators that determine its essence and affect the state of the project during its life cycle. This set of project elements are essentially objects of management. The history of various approaches to project management is five thousand years old, although the first mention of project management was given in the early 20th century. The founders of project management can be called the main three scientists: Henry Gant (1861–1919) was an American engineer who in 1910 created and implemented a calendar planning approach in which horizontal elements became the basis for constructing diagrams. In fact, his invention of such planning was later called the Gantt chart. Frederick Winslow Taylor (1856-1915) - American engineer, mathematician and physicist, his work is still used as prototypes of various modern tools, which includes the hierarchical structure of his work. Henri Fayol (1841–1925) was a French engineer who founded the main classical project management model. He became quite famous due to the fact that he described the 5 main functions of management (management), which, in fact, became the basis of the theory of project management. Theoretical aspects of research on project management are contained in the works of such Ukrainian and foreign scientists as, in particular, OO Kulinich, SD Bushuyev, Yu.S. Грисюк, І.В. Kononenko, VI Максимова, В.Б. Силова, Є.К. Корноушенко, О.Г. Timinsky, VI Prangishvili, Dolores Sherwood Steiger, Yu.M. Tesla, Paula Martin, Karel Tate, L.A. Zade, Denise Colonna d’Istria. In their works, they covered the development of information technology in project management. The reason for the relevance of an effective planning process is the need to increase human capacity to solve unique problems. Quite often companies implement several projects at the same time, which involve the same human or technical resources. Automating this process can increase the efficiency of the company as a whole. To date, there are many examples of efficiency by automating monotonous manual work. Connection of work with scientific programs, plans, themes. The work was performed at the Department of Automated Information Processing and Control Systems of the National Technical University of Ukraine "Kyiv Polytechnic Institute. Igor Sikorsky ”in the framework of the topic "Effective methods for solving problems of schedule theory" (№ DR 0117U000919). The purpose of the study is to increase the efficiency of IT projects in the company, by creating an information system for resource planning of IT projects, which is based on methods that minimize the time of project implementation. To achieve this goal it is necessary to perform the following tasks:  perform an analytical review and conduct a detailed analysis of existing systems of resource planning, project management, management of constraints and risks within the project, methods of planning schedules for tasks within resource constraints;  develop algorithms for solving the problem of supporting the work of the resource planning system of IT projects;  investigate the effectiveness of the developed algorithms;  develop software implementation of information system for resource planning of IT projects;  perform an experimental study of the developed information system, methods of solving the problem and the effectiveness of the algorithms used. The object of research is the process of planning IT project resources. The subject of research - there are methods of automation of resource planning of IT projects. The research methods used in this paper are based on methods for solving the problem of resource planning. The scientific novelty of the obtained results is to build a method of resource planning, taking into account their limitations, risks and analysis; development and improvement of algorithms for solving the problem by performing experimental research. Publications. Materials of the work are published in the collection of the Fifteenth International Scientific and Practical Conference MATHEMATICAL AND SIMULATION MODELING OF SYSTEMS (MODS 2020), as well as in the materials of the V All-Ukrainian Scientific and Practical Conference of Young Scientists and Students "Management and Technology" Information.

Every day we complete a number of tasks which require us to accurately time events, from estimating how long it will take us to drive to work in the morning to steeping our afternoon tea for the correct duration. Although timing is very important in our everyday lives, we know relatively little about how we process time information. Many models have been proposed to account for human timing, with the most prominent are the attentional gate model (AGM) and the multiple resources model. The AGM and the multiple resources model make many similar predictions about human timing, and it is often difficult to discriminate between the two. Toward this goal, the present research focused on a situation in which the two models make opposing predictions, that is, conditions which require participants two carry out two tasks concurrently with both of them requiring time-related processing.. Three experiments are reported, in which subjects were asked to estimate various shorter or longer intervals while concurrently carrying out a task that either required processing of time-related information or non-time based information. Results of all three studies seem more supportive of the multiple resources model of timing, rather than the AGM.

In this thesis, a maximum likelihood receiver to obtain the target range profile that uses the clutter prediction derived from the target-free previous observations is suggested as a fast time processor for pulse compression radar systems. The maximum likelihood receiver is proposed to overcome the range sidelobe problem, which is introduced by the pulse compression method. Conventional methods, such as the matched filter receiver, as fast time processor result in the targets with high radar cross sec- tion masking the low radar cross section targets at the neighboring range cells
since sidelobes of the matched filter is determined by the autocorrelation of the spreading code and linearly proportional to target signal power. An unbiased estimator, like the maximum likelihood receiver in this thesis work does not su&crarr
er from such issues. In addition to that, to suppress the signal dependent interference, namely the clutter, at the output of fast time processor
the previous target-free observations are col- lected and utilized to predict the clutter signal for next time instant. This prediction is used in the maximum likelihood receiver. The clutter prediction is done for the stationary case and the internal clutter motion case, and their SINR performances with the maximum likelihood receiver are evaluated. In conclusion, such an approach managed to have an unbiased estimation of target range profile and the clutter suppression advantage in the fast time.

The thesis addresses time-domain inverse electromagneticscattering for determining unknown characteristics of an objectfrom observations of the scattered .eld. Applications includenon-destructive characterization of media and optimization ofmaterial properties, for example the design of radar absorbingmaterials.A nother interesting application is the parameteroptimization of subcell models to avoid detailed modeling ofcomplex geometries.

The inverse problem is formulated as an optimal controlproblem where the cost function to be minimized is thedi.erence between the estimated and observed .elds, and thecontrol parameters are the unknown object characteristics. Theproblem is solved in a deterministic gradient-basedoptimization algorithm using a parallel 2D FDTD scheme for thedirect problem.This approach is computationally intensive sincethe direct problem needs to be solved in every optimizationiteration in order to compute an estimated .eld.H ighlyaccurate analytical gradients are computed from the adjointformulation.In addition to giving better accuracy than .nitedi.erences, the analytical gradients also have the advantage ofonly requiring one direct and one adjoint problem to be solvedregardless of the number of parameters.

When absorbing boundary conditions are used to truncate thecomputational domain, the equations are non-reversible and theentire time-history of the direct solution needs to be storedfor the gradient computation.Ho wever, using an additionaldirect simulation and a restart procedure it is possible tokeep the storage at an acceptable level.

The inverse method has been successfully applied to a widerange of industrial problems within the European project,IMPACT (Inverse Methods for Wave Propagation Applications inTime-Domain).T he results presented here includecharacterization of layered dispersive media, determination ofparameters in subcell models for thin sheets and narrow slotsand optimization problems where the observed .eld is given bydesign objectives.

Thesis (M.S.) -- Worcester Polytechnic Institute.
Keywords: uniformity of heating; optimization; optimal process; modeling; microwave pulsing; microwave heating; FDTD method; coupled problem. Includes bibliographical references (leaves 50-59).

Every day, robots are being deployed in more challenging environments, where they are required to perform complex tasks. In order to achieve these tasks, robots rely on intelligent deliberation algorithms. In this thesis, we study two deliberation approaches – task scheduling and task planning. We extend these approaches in order to not only deal with temporal and spatial constraints imposed by the environment, but also exploit them to be more efficient than the state-of-the-art approaches. Our first main contribution is a scheduler that exploits a heuristic based on Allen’s interval algebra to prune the search space to be traversed by a mixed integer program. We empirically show that the proposed scheduler outperforms the state of the art by at least one order of magnitude. Furthermore, the scheduler has been deployed on several mobile robots in long-term autonomy scenarios. Our second main contribution is the POPMERX algorithm, which is based on merging of partially ordered temporal plans. POPMERX first reasons with the spatial and temporal structure of separately generated plans. Then, it merges these plans into a single final plan, while optimising the makespan of the merged plan. We empirically show that POPMERX produces better plans that the-state-ofthe- art planners on temporal domains with time windows.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 103-110).
In time-sensitive and dynamic missions, autonomous vehicles must respond quickly to new information and objectives. In the case of dynamic task allocation, a team of agents are presented with a new, unknown task that must be allocated with their original allocations. This is exacerbated further in decentralized settings where agents are limited to utilizing local information during the allocation process. This thesis presents a fully decentralized, dynamic task allocation algorithm that extends the Consensus-Based Bundle Algorithm (CBBA) to allow for allocating new tasks. Whereas static CBBA requires a full resetting of previous allocations, CBBA with Partial Replanning (CBBA-PR) enables the agents to only partially reset their allocations to efficiently and quickly allocate a new task. By varying the number of existing tasks that are reset during replan, the team can trade-off convergence speed with amount of coordination. By specifically choosing the lowest bid tasks for resetting, CBBA-PR is shown to converge linearly with the number of tasks reset and the network diameter of the team. In addition, limited replanning methods are presented for scenarios without sufficient replanning time. These include a single reset bidding procedure for agents at capacity, a no-replanning heuristic that can identify scenarios that does not require replanning, and a subteam formation algorithm for reducing the network diameter. Finally, this thesis describes hardware and simulation experiments used to explore the effects of ad-hoc, decentralized communication on consensus algorithms and to validate the performance of CBBA-PR.
by Noam Buckman.
S.M.

A thesis submitted to the Faculty of Education in partial fulfilment of the requirements for the Degree of Master of Education in the Department of Social Science Education at the University of Zululand, South Africa, 2014
Effective time utilisation leads to greater freedom to use time as one would like to: to do more of the things one has always wanted to do; in short to enjoy life more. Like in any other business organisation, time for planning, organising, leading and controlling is managed carefully. The principal needs time to perform all the above mentioned tasks. In this study, the author accentuates that it is disconcerting that from time to time, there are schools that do not even have a time table when the schools open at the beginning of the year. It would be interesting to know how much time might be wasted as a result of a lack of planning, lack of priorities, paperwork and reading, meetings, unclear objectives, procrastination, lack of delegation, incompetent subordinates and many other time wasters. The purpose of the study was to determine the school principal’s understanding of the time management task and explore how effective school principals manage time in performing their different tasks. Fifty principals from Phumelela and Umbumbulu Circuits, under the Umlazi District completed a survey questionnaire and semi structured interviews were conducted. The researcher was able to determine the pattern of time usage. The findings revealed that factors hampering time management include among other things meetings that principals have to attend, departmental expectations, visitors, the organisational stress, administrative obligations and inability to differentiate between urgent and important matters to attend to hampers the principal’s time management tasks. The study among other things recommended that the provincial education departments need to provide appropriate training for school governing bodies that a well organised and goal directed system should operate to control school visitors in the schools’ interest.

Real-time detection and extraction of visual features in wireless sensor networks is a challenging task due to its computational complexity and the limited processing power of the nodes. A promising approach is to distribute the workload to other nodes of the network by delegating the processing of different regions of the image to different nodes. In this work a solution to optimally schedule the loads assigned to each node is implemented on a real visual sensor network testbed. To minimize the time required to process an image, the size of the subareas assigned to the cooperators are calculated by solving a linear programming problem taking into account the transmission and processing speed of the nodes and the spatial distribution of the visual features. In order to minimize the global workload, an optimal detection threshold is predicted such that only the most significant features are extracted. The solution is implemented on a visual sensor network testbed consisting of BeagleBone Black computers capable of communicating over IEEE 802.11. The capabilities of the testbed are also extended by adapting a reliable transmission protocol based on UDP capable of multicast transmission. The performance of the implemented algorithms is evaluated on the testbed.

"January 2003" Includes bibliographical references (leaves 120-129) Presents performance analyses of dynamic, stochastic task scheduling policies for a real- time-communications system where tasks lose value as they are delayed in the system.

Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2007.
Title from electronic title page (viewed Mar. 27, 2008). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Computer Science." Discipline: Computer Science; Department/School: Computer Science.

The purpose of this study was to determine teacher and program effectiveness in Consumer and Homemaking Programs in Arizona by using time on task as a measure. In effective program studies, the common critical variable was the individual teacher (Brophy, 1979; McGreal and McGreal, 1986). Teachers who were organized, started class on time and kept the students busy with relevant work maintained high time on task percentages. Using time on task as a measurement of effectiveness, the "Managing Learning Time" instrument (Halasz and Desy, 1984), was used. This study: determined that the majority of students were on task in Arizona Consumer and Homemaking Education classrooms. Time on task was affected more by teacher and classroom practices than by the course content. The focus of the on task behavior varied by subject matter. The majority of time was spent on theory, practice and basic skills in Consumer and Homemaking courses.

Whilst considerable research has found that people tend to underestimate their task completion times (e.g., Buehler et al., 1994), factors that might influence the accuracy of temporal predictions have received little empirical treatment. The research presented in this thesis identified two distinct factors that mediated time estimation accuracy and bias. One factor was task duration, whereas the other factor was the person’s prior experience of the task. There was evidence that having prior experience of performing all or a substantial part of the same task enabled participants to more accurately estimate its duration. Additionally, predictions were more accurate when participants viewed tasks before making time estimates. Contrary to the theory of the planning fallacy (Kahneman & Tversky, 1979), these findings suggest that people do take account of their previous task performance, and use such distributional information to good effect. However, there was evidence of time prediction bias when unrelated tasks were completed beforehand, suggesting that erroneous information about previous task performance was used when making a subsequent estimate. The directional nature of time estimation bias was also highlighted in the present research. In general, there was some evidence of temporal overestimation on tasks with a duration of up to four or five minutes, whereas participants tended to underestimate their completion times on tasks that took between eight and 16 minutes to complete. These findings indicate that task duration influences the direction in which time estimates are biased (i.e., under or overestimation), with the temporal underestimation indicative of the planning fallacy occurring on tasks of at least eight minutes' duration. The present research has potential implications for task duration estimation in everyday life, and outlines conditions under which prediction bias can be reduced. The present findings are discussed in relation to the theory of the planning fallacy and the potential role of cognitive judgemental heuristics in determining temporal misestimation.

Werden zwei Aufgaben in einem Doppelaufgaben-Paradigma gleichzeitig bearbeitet, dann treten oft sogenannte Doppelaufgabenkosten auf (längere Reaktionszeiten und/oder höhere Fehlerzahlen). Diese Doppelaufgabenkosten werden durch einen zentralen “Flaschenhals” erklärt, der die gleichzeitige Verarbeitung der beiden Aufgaben an der zentralen Verarbeitungsstufe der Reaktionsauswahl verhindert. Das Ziel der vorliegenden Arbeit war es, einige mögliche Faktoren der Verarbeitungsreihenfolge an diesem Flaschenhals zu untersuchen. Die Studie zeigt, dass die Ankunftszeit am Flaschenhals ein wichtiger Faktor bei der Festlegung der Verarbeitungsreihenfolge ist. Zusätzlich ist der Einfluss der Ankunftszeit auf die Verarbeitungsreihenfolge unabhängig davon, welche der beiden Aufgaben manipuliert wurde um den Einfluss dieser Aufgabe zu untersuchen (visuelle oder auditorische Aufgabe). Ein zweiter Faktor der manipuliert wurde, ist die Instruktion an die Probanden. Die Ergebnisse zeigen, dass unter bestimmten Instruktionsbedingungen kognitive Kontrollprozesse aktiviert zu werden scheinen. Als dritten Faktor wurden Aufgabenanforderungen untersucht, indem eine Aufgabe mit zeitlicher Reihenfolge-Entscheidung mit einer Doppelaufgabe mit zufälliger Aufgabenreihenfolge, d.h.: Bestimmung der zeitlichen Reihenfolge mit der zusätzlichen Anforderung einer Reaktionswahl-Aufgabe, verglichen wurde. Die Ergebnisse dieser Experimente deuten darauf hin, dass die Entscheidung über die zeitliche Reihenfolge der beiden Aufgaben zwischen der Wahrnehmungsstufe und der Reaktionswahlstufe getroffen wird.
The simultaneous performance of two tasks in a dual-task paradigm is often accompanied by dual-task costs (longer reaction times and/or higher error rates). These dual-task costs have been explained by the existence of a central bottleneck which prohibits the simultaneous processing of the two tasks at the central response-selection stage of information processing. The aim of the present work was to investigate several of the possible factors which determine the task processing order at this central bottleneck. The study shows that the arrival time of the two tasks at the bottleneck plays an important role in the determination of task order. Additionally, the influence of the arrival time on processing order is independent of the component task which is manipulated to test the influence of that task (i.e., visual & auditory task). A second factor that was manipulated is the instruction given to the participants. The results show that cognitive control processes are activated under certain instruction conditions. As a third factor, task requirements were investigated by comparing a temporal order judgement task with a dual task with random task order (i.e., temporal order judgement with the additional requirement to do a choice-RT task). The results suggest that the decision about the temporal order of the two tasks is located between the perception stage and the response-selection stage of processing.

The purpose of this research is to develop a heuristic algorithm to minimize total costs in multi-commodity, multi-mode generalized networks with time windows problems. The proposed mathematical model incorporates features of the congestion of vehicle flows and time restriction of delivering commodities. The heuristic algorithm, HA, has two phases. Phase 1 provides lower and upper bounds based on Lagrangian relaxations with subgradient methods. Phase 2 applies two methods, early due date with overdue-date costs and total transportation costs, to search for an improved upper bound. Two application networks are used to test HA for small and medium-scale problems. A different number of commodities and various lengths of planning time periods are generated. Results show that HA can provide good feasible solutions within the reasonable range of optimal solutions. If optimal solutions are unknown, the average gap between lower and upper bounds is 0.0239. Minimal and maximal gaps are 0.0007 and 0.3330. If optimal solutions are known, the maximal gap between upper bounds and optimal solutions is less than 10% ranges of optimal solutions.

The ratings of perceived exertion (RPE) are a widely accepted measure used to quantify, monitor and subjectively regulate an individual's exercise tolerance and level of exertion. Despite recent encouraging findings (Eston et ai, 2005, 2006), the predictive utility of the RPE during estimation and perceptually-regulated exercise tests (production) has been studied infrequently.

Almost 100 years ago, Jersild (1927) published his article “Mental Set and Shift”. He borrowed this title from a book of Hollingworth and Poffenberger (1919), according to whom “shifting back and forth from one mental set, one attitude or one task to another, is a relatively ineffective mode of work.” As pointed out by Jersild, the cost of switching between activities or mental sets is, for instance, the reason for Taylor’s model of industrialization and the trend in industry toward specialization. Through specialization, the element of switch is reduced to its minimum because “the cost of shift is loss in efficiency” (Jersild, 1927). However, outside of the factory, switching between multiple tasks is a crucial part of human life and the cost of switching, consequently, impacts our everyday functioning.The main topic of this doctoral dissertation is cognitive flexibility and task switching. The task-switching paradigm requires participants to switch frequently between tasks. Therefore, it measures the capacity of our brain to adapt rapidly according to tasks and goals. Dynamic adaptation according to context and goals is encompassed in cognitive psychology and neurosciences under the term cognitive control. Consequently, the ability to switch between tasks constitutes the part of cognitive control that is needed when the current goal changes and the cognitive system has to adapt. Our experimental contribution aimed at investigating how this task-goal switching can be modulated by factors such as time, language, alertness and expertise. In this introduction, we succinctly review the vast literature about attentional systems, cognitive control and task switching. In the experimental section, we describe the cued match-to-sample task that we developed to investigate task-goal switching and present five experimental studies that address the impact of several factors on task-goal switching. In the general discussion, we summarize our results and consider their implications for cognitive-control and task-switching literatures.
Doctorat en Sciences psychologiques et de l'éducation
info:eu-repo/semantics/nonPublished

Thesis (Ph. D.)--University of California, San Diego, 2009.
Title from first page of PDF file (viewed August 20, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 178-184).

It is well established that aging is associated with numerous health concerns, including poor balance. Deteriorations in attention demand also place older adults at a greater risk for falls. Emerging experiments have explored the impact of dual-task training programs and have improved dual-tasking in older adults. However, it is unknown whether these performance-related improvements are a function of the intervention itself or the repeated exposure to the testing protocol. Study 1 explored the implications of repeated administration, once per week for 5 weeks, of a protocol involving standing postural sway while concurrently performing reaction time (RT) tasks in older adults. Results revealed that postural sway was stable across testing sessions whereas the difficult RT task gradually improved over time. Study 2 examined the influence of repeated exposure, once per week for 5 weeks, of a protocol involving negotiating a series of obstacles while performing RT tasks in older adults. Participants walked significantly faster with repeated exposure and gradually improved RT. Study 3 investigated the impact of repeated exposure, once per week for 5 weeks, to three functional mobility measures in older adults. It also examined the influence of a 12-week balance and mobility training (BMT) program as well as a 12-week balance and mobility plus cognitive training (BMT+C) program on functional mobility in older adults. Functional mobility served to be stable over time. Both the BMT and BMT+C groups significantly improved functional mobility and sustained these improvements at the 12-week follow-up, while no changes were observed in the control group. No differences between the BMT and BMT+C groups emerged. Experiment 4 examined the influence of BMT and BMT+C on postural sway and RT in older adults. Participants in both training groups significantly improved RT and sustained these improvements at the follow-up, while no changes were observed in the control group. No changes to postural control were shown in any group. No differences between the BMT and BMT+C groups emerged. Experiment 5 examined the influence of BMT and BMT+C on negotiating a series of obstacles while performing RT tasks in older adults. Both the BMT and BMT+C groups significantly improved RT and sustained these improvements at the follow-up, while no changes were observed in the control group. All groups showed faster time to completion of the obstacle series. No differences between the BMT and BMT+C groups emerged. Collectively, these findings suggest that BMT and BMT+C significantly improve functional mobility and divided attention, and sustain these improvements over time. Although some improvements were observed after repeated exposure over 5 weeks, no changes in the control group were observed. Therefore, the improvements exhibited from BMT and BMT+C are likely not a function of repeated exposure to the testing protocol, as participants may be more susceptible to performance-related improvements when the testing sessions are close in proximity. Altogether, these findings propose that, whether or not cognitive training is included, attention demanding dual-task training not only improves functional mobility and RT, but also sustains these improvements over time in older adults. These results may be used to improve the prescription of exercise in older adults.

Over the past several decades, we have experienced tremendous growth of real-time systems in both scale and complexity. This progress is made possible largely due to advancements in semiconductor technology that have enabled the continuous scaling and massive integration of transistors on a single chip. In the meantime, however, the relentless transistor scaling and integration have dramatically increased the power consumption and degraded the system reliability substantially. Traditional real-time scheduling techniques with the sole emphasis on guaranteeing timing constraints have become insufficient. In this research, we studied the problem of how to develop advanced scheduling methods on hard real-time systems that are subject to multiple design constraints, in particular, timing, energy consumption, and reliability constraints. To this end, we first investigated the energy minimization problem with fault-tolerance requirements for dynamic-priority based hard real-time tasks on a single-core processor. Three scheduling algorithms have been developed to judiciously make tradeoffs between fault tolerance and energy reduction since both design objectives usually conflict with each other. We then shifted our research focus from single-core platforms to multi-core platforms as the latter are becoming mainstream. Specifically, we launched our research in fault-tolerant multi-core scheduling for fixed-priority tasks as fixed-priority scheduling is one of the most commonly used schemes in the industry today. For such systems, we developed several checkpointing-based partitioning strategies with the joint consideration of fault tolerance and energy minimization. At last, we exploited the implicit relations between real-time tasks in order to judiciously make partitioning decisions with the aim of improving system schedulability. According to the simulation results, our design strategies have been shown to be very promising for emerging systems and applications where timeliness, fault-tolerance, and energy reduction need to be simultaneously addressed.

Thesis (Ph.D.)--Case Western Reserve University, 2009
Title from PDF (viewed on 26 May 2009) Includes abstract Department of Psychology Includes bibliographical references and appendices Available online via the OhioLINK ETD Center

This is an analysis of the task system, the primary form of labor organization used by South Carolina and Georgia lowcountry rice planters. It examines the labor process of rice field hands, analyzes the extent to which gender shaped enslaved men and women's experiences of tasking, and explores some of the ramifications of task work on field women's lives. Conventional interpretations of the task system claim that it provided slaves with more autonomy, control, and opportunities for individual initiative than gang labor did. In contrast, this study finds that tasking was a multifaceted labor regime whose differences from gang labor were less pronounced than previous scholarship suggests. Specifically, structural, seasonal, and managerial constraints profoundly limited slaves' ability to control their work pace and to independently manage their work routines. As a result, slaves' access to own time and autonomy could be quite limited. Significantly, field hands did not experience these limits equally. Since planters did not adhere to one uniform model of rice cultivation, task assignments and labor routines varied across plantations. This heterogenous organization of task labor meant that slaves' ability to realize tasking's potential for greater slave autonomy was disproportionate across plantation boundaries. Gender also affected slaves' access to own time. Field women's control over the length of their work day and hence over access to own time was particularly circumscribed. The origins of these limits can be found in how planters organized their labor force and allocated field work. Given these constraints, slaves clearly did not gain own time easily. Nevertheless, slaves persevered in their quest for any or more own time by trying to circumvent prescribed work routines. Historians have touted slave family assistance as one of the most important of their strategies. While true, such aid was complex, circumscribed, and sometimes gendered. Finally, I link these labor and aid patterns to field women's reproductive histories and find that they help explain the region's high rate of slave neonatal mortality. These findings provide compelling evidence that we need to lower our assessment of the relative benefits putatively enjoyed by slaves who worked in a task regime.

Systems controlled by embedded computers become indispensable in our lives and can be found in avionics, automotive industry, home appliances, medicine, telecommunication industry, mecatronics, space industry, etc. Fast, accurate and flexible performance estimation tools giving feedback to the designer in every design phase are a vital part of a design process capable to produce high quality designs of such embedded systems.

In the past decade, the limitations of models considering fixed task execution times have been acknowledged for large application classes within soft real-time systems. A more realistic model considers the tasks having varying execution times with given probability distributions. No restriction has been imposed in this thesis on the particular type of these functions. Considering such a model, with specified task execution time probability distribution functions, an important performance indicator of the system is the expected deadline miss ratio of tasks or task graphs.

This thesis proposes two approaches for obtaining this indicator in an analytic way. The first is an exact one while the second approach provides an approximate solution trading accuracy for analysis speed. While the first approach can efficiently be applied to monoprocessor systems, it can handle only very small multi-processor applications because of complexity reasons. The second approach, however, can successfully handle realistic multiprocessor applications. Experiments show the efficiency of the proposed techniques.

Report code: LiU-Tek-Lic-2002:58.

Time-based prospective memory has been found to be negatively affected by aging, possibly as a result of the declining frontal function that often accompanies aging. In the present study we investigated the role of the frontal lobes in prospective memory. Based upon their scores on a composite measure of frontal function, 32 older adults were characterized as possessing high- or low-frontal function, and were then tested on a time-based laboratory prospective memory task. Overall age effects were also assessed and each of the frontal groups was compared to a group of 32 younger adults. High-frontal functioning participants demonstrated better prospective memory than low-frontal functioning participants, and were not distinguishable from younger adults. The results of this study suggest that it is not aging per se that disrupts prospective memory performance, but it is instead the diminished frontal function seen in a subset of older adults.

Recently, we have seen an increase in the deployment of safety critical embedded systems in rapidly changing environments, as well as requirement for on-site customizations and rapid adaptation. To address the extended range of requirements, adaptation mechanism are added to the systems to handle large number of situations appropriately. Although necessary, adaptations can cause inconsistent and unstable configurations that must be prevented for the embedded system to remain dependable and safe. Therefore, verifying the behavior of adaptive embedded systems during the design phase of the production process is highly desirable. A hard real time embedded system and its environment can be modeled using timed automata. Such model can describe the system at various levels of abstraction. In this thesis, we model the adaptive responses of a system in terms of tasks that are executed to handle changes in the environmental or internal parameters. Schedulability, a property that all tasks complete execution within their respective deadlines, is a key element in designing hard real-time embedded systems. A system that is unschedulable immediately compromises safety and hard real-time requirements and can cause fatal failure. Given specifications of all tasks in the system, we can model the system, an abstraction of the environment, and adaptive strategies to investigate whether the system retains safety properties, including schedulability, regardless of the changes in the environment and adaptations to those changes.

This study was designed to collect and evaluate the social networks of 32 study abroad students participating in the 2009 BYU study abroad program in Amman, Jordan. Survey data, language journals, and test scores were analyzed to determine how they successfully built social networks with native speakers, the relationship between students' social networks and time spent using Arabic outside of class, and the relationship between students' social networks and their acquisition of Arabic. The experiment provided a number of insights into how study abroad students meet potential conversation partners, select which relationships to pursue, and develop relationships in order to build social networks. The study also found that the intensity of students' social relationships as well as the number of clusters in their social networks were predictors of language gains. Additionally, the findings show that social network dispersion and the size of the largest cluster in a network predicted time spent using Arabic outside of class.

With globally increased migration and mobility between countries, it has become critical for many people to learn to speak a second language. The focus of this study is on adult migrant language learners that are learning a second language of the host country on the side of their working life. This study aims to support learners in their second language acquisition outside classrooms settings. In particular, it explores how the use of a specially designed application aimed at helping learners to keep track on how much time they spend on studying a second language affects their engagement and motivation to continue study the target language. To support migrant learners keeping track of the time spent on language learning activities (e.g., speaking, writing, reading and listening), a web-based application, the TimeTracker App, accessible through users’ mobile device has been developed by the researcher and offered to the learners. Participants in this study used the application for around two weeks. A mixed method approach was employed: data was collected through semi-structured interviews and by extracting log data from the application’s database. Interview data was analysed by means of a conventional content analysis and log data by using descriptive statistics. Overall, the study’s results show that the use of the TimeTracker App enabled the respondents to feel more aware of how much time they spent on their studies, and inspired them to devote more time to study the target language compared to before using the application. The findings suggest that migrant learners become more motivated and engaged in their second language learning when using the application.
Globalt ökad migration och rörlighet mellan länder har gjort det kritiskt för många att lära sig att tala ett andraspråk. Denna studie fokuserar på arbetande migranter som lär sig ett andraspråk vid sidan av sitt arbetsliv. Studien syftar till att stödja de studerande i sitt lärande av ett andraspråk utanför klassrummet. I synnerhet undersöker den hur användningen av en speciellt utformad applikation som syftar till att hjälpa eleverna att hålla reda på hur mycket tid de spenderar på att studera ett andraspråk påverkar deras engagemang och motivation för att fortsätta studera målspråket. För att hjälpa studerande migranter hålla reda på den tid som spenderas på språkinlärning (t ex att tala, skriva, läsa och lyssna) har en webbaserad applikation, TimeTracker App, som är tillgänglig via användarnas mobiltelefon, utvecklats av författaren och erbjudits till eleverna. Deltagarna i denna studie använde applikationen i cirka två veckor. En blandad metod användes: data samlades in genom halvstrukturerade intervjuer och genom att extrahera loggdata från applikationsdatabasen. Intervjudata analyserades med hjälp av en konventionell innehållsanalys och loggdata med hjälp av beskrivande statistik. Sammantaget visar studiens resultat att användningen av TimeTracker App gjorde det möjligt för respondenterna att bli mer medvetna om hur mycket tid de spenderade på sina studier och det inspirerade dem att ägna mer tid att studera målspråket jämfört med innan man använde applikationen. Resultaten tyder på att arbetande migranter blir mer motiverade och engagerade i sitt studerande av ett andraspråk när de använder applikationen.

This research is about the information behaviour of organizational members in different contexts while dealing with the work tasks. The objectives of the research are to provide an understanding of information seeking, using, and sharing through illuminating answers to “How is organizations’ information behaviour shaped with regard to time pressure and task complexity?” and “How do organisational members process information in collaborative settings and decide for the next actions in stable vs. unstable environments?” questions. In work settings, tasks are commonly carried out in groups; information is processed in collaborative manner and affected by situational factors (time and complexity). However, relatively small number of articles presents collaborative information behaviour and its link to situational factors. To contribute to the existing literature, the research aims to explore collaborative information behaviour while carrying out tasks in varying complexity and under time pressure. The research uses qualitative methodology. Data have been collected from Cihan News Agency-Istanbul (CIHAN) and Istanbul Metropolitan Municipality Disaster Coordination Centre (AKOM) through field observations and interviews. It is a cross case study exploring the differences and commonalities of the information behaviour in two different contexts and two different situations. The interview transcripts and field observation have been interpreted to explain the decision making mode of the organisational members in dynamic environments and the way they process information; and grounded theory approach is used to construct collaborative information behaviour model for the CIHAN and AKOM contexts. Information behaviour models, which are illuminating collaborative information behaviour (CIB), have been introduced as the first contribution of the research. Time pressure and varying task complexity shape the model through illuminating barriers to access information and complex needs of the tasks carried out. The second contribution lies in clarifying the interaction between information behaviour and decision making type (intuitive vs analytical) under time pressure. Time pressure and the nature of the work tasks drive organisational members to use intuition or analytical mode. Activity Theory has been used as the theoretical framework and methodological tool for the research. Activity Theory has been used to investigate individual information behaviour in the literature. Use of Activity Theory to investigate collaborative information behaviour is the methodological contribution.

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on November 13, 2009). Thesis advisor: Dr. Jeffrey Rouder. Includes bibliographical references.

Younger adults who are walking and doing additional tasks at the same time may not realize if their performance suffers, putting some at greater risk for injury and impairment during certain tasks. This thesis has addressed this confound by developing a divided attention paradigm focusing on discrete and continuous demand manipulations. The work assessed in motorcognitive processing changes with cerebral and behavioral monitoring of over-ground walking with or without cognitive tasks. Participants (n = 19, 18-35 years, 13 females) were asked to walk at their usual pace [usual walking condition (SM)], walk at their usual pace while performing a cognitive task [dual-task condition (DT)] as well as conduct a cognitive task while standing [single cognitive condition (SC)]. All participants conducted two discrete [simple response time (SRT) & go-no-go (GNG)] and two continuous cognitive tasks [N-back (NBK) & double number sequence (DNS)] of increasing demand. The study revealed significant brain and behavior interactions during the most demanding continuous cognitive task, the DNS. The findings demonstrated lower accuracy rates, slower walk speeds as well as greater cerebral oxygenation in DNS DT in comparison to single task conditions. With increasing cognitive demands and tasks, there were longer response times, as well as lower accuracy rates. The behavioral findings were qualified by marginally significant interactions in a 2 x 4 RM ANOVA between SC-DT task and demand for accuracy rate [F (3, 54) = 2.66, p = 0.06, η2 =.13], significant interactions in response time [F (2, 36) = 4.1, p = 0.026, η2 =.18] as well as significant SM-DT task and demand findings for walk speed [F (3, 54) =5.3, p = 0.003, η2 =.23]. The 2 x 2 x 4 RM ANOVA revealed significant HbO2 interactions between walking tasks (single and dual), hemisphere and demand [F (3, 54) = 5.730, p = 0.002, η2 =.24] in the DNS only. The data suggests that greater demand manipulations with continuous cognitive tasks may be sensitive to both prefrontal cortex (PFC) and behavioral assessments in younger adults (YA). Further validation of the discrete-continuous demand paradigm in motor studies may provide a basis for cognitive assessment with applications in motor learning, cognitive training, aging and more.

Real-time task scheduling problems are generally considered to be NP-hard problems. Therefore it is necessary to apply a heuristic search strategy on these problems. This project focuses on the development of a real-time scheduling algorithm using tabu search.

A dynamic real-time task scheduling problem is defined for a single processor. The tasks in the system are sporadic, mutually independent, non-preemptable with firm, arbitrary deadlines. This problem is represented with tabu search. For performance measurements a simulator has been designed and implemented. Simulations have been conducted comparing scheduler based on tabu search to two well known scheduling algorithms, namely: earliest deadline first and highest value first. It was expected that the scheduler based on tabu search would outperform highest-value first and it would miss fewer deadlines than earliest deadline, as soon as earliest deadline starts to miss deadlines. The results of the simulations conducted did not show this results. Nevertheless did the simulation results indicate that tabu search could be a suitable heuristic search strategy for real-time task scheduling problems. This project provides a starting point on which it is possible to continue work on enhancing the tabu search scheduler.