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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Effectiveness of Grid Systems for Pheromone-Trapping Sparse Gypsy Moth Populations in Mountainous Terrain in the Intermountain West

Keyes, Colleen 01 May 1997 (has links)
Two field experiments determined an effective intertrap distance (ITD) for early detection and delimitation sparse gypsy moth (Lepidoptera: Lymantriidae, Lymantria dispar L.) populations in mountainous terrain. This study found that current Animal and Plant Health Inspection Service trapping guidelines are not sufficient for early detection of small gypsy moth populations in mountainous terrain. Detection trapping in mountainous terrain should have an ITD of not more than 804 m. Delimiting trapping should use a grid design with an ITD of 152 m. A related study determined natural adult male mortality in the climate of the intermountain West, which includes Utah, Nevada, western Wyoming, and southern Idaho. An interaction was found between mortality, temperature, and humidity. During high temperatures, most mortality occurred on the second day. When lower temperatures prevailed, the largest percent mortality occurred on the third or fourth day.
2

Techno-economic study of second-life EV batteries as alternative energy storage and comparison with lead-acid and new Li-ion batteries in off-grid PV systems

Arumugam, Vijay January 2022 (has links)
The global EV stock is expected to increase from 7.2 million in 2019 to nearly 140 million vehicles by 2030. So, the demand for the battery also increases due to the increase in the number of EVs. In any EV, battery degradation is an unavoidable phenomenon and EV batteries are assumed to arrive at their end-of-life in EV application when the state of health reaches 80 %, repurposing the eligible EV batteries after end of first life is expected to extend their lifetime by another 5-15 years in the second life applications.  This thesis aims to conduct a techno-economic study on the usage of second life EV batteries as an alternative storage option in off-grid PV systems compared to lead-acid batteries and new Li-ion batteries. A single-family house with an annual demand of 2245 kWh/year located in Athens was chosen as the primary location, the off-grid PV system is pre-sized for Athens and based on the pre-sizing results and what is state of art in the market. The system components were chosen for system design (4 kW bi-directional inverter, 2.9 kW PV array, 7.2 kW genset and three battery bank options i.e., 16.5 kWh of lead-acid, 8 kWh new Li-ion and 12.6 kWh of second life EV battery). PV off-grid system with different storage options is simulated using HOMER for both locations and the results are compared.   The simulation results show that the designed off-grid PV system can reach a solar fraction of 90 % in Athens and 73 % in Gotland when 16.5 kWh of lead-acid batteries are used with an allowed depth of discharge of 50 %. When a new Li-ion battery of 8 kWh with an allowed depth of discharge of 80 % is used then the achievable solar fraction is 84 % in Athens and 71 % in Gotland, When the second life EV battery of 12.6 kWh with an allowed depth of discharge of 60 % is used then the achievable solar fraction is 90 % in Athens and 74 % in Gotland. Sensitivity analysis is performed on the depth of discharge and results showed that the solar fraction can be increased by allowing the battery to discharge more, but it also decreases the battery lifetime.   The simulation results also show that the net present cost was lower in Athens for all the reference cases compared to Gotland. Net present cost and levelized cost of electricity for the off-grid system are 25.3 k€, 0.9 €/kWh in Athens and 29.2 k€, 1.0 €/kWh in Gotland when a lead-acid battery is used. When a new Li-ion battery is used then 26.2 k€, 0.9 €/kWh in Athens and 29.3 k€, 1.0 €/kWh in Gotland, when the second life EV battery is used then 26.7 k€, 0.9 €/kWh in Athens and 30.7 k€, 1.1 €/kWh in Gotland.   Overall, the net present cost and levelized cost of electricity are lower in Athens in all cases compared to Gotland. For the reference house in Athens, lead acid battery system has shown slightly lower net present cost than new Li-ion battery and second life EV battery. For the reference house in Gotland, both lead acid battery and new Li-ion battery system have shown similar net present cost and they are slightly lower than second life EV battery.   Also, the second life EV battery levelized cost of electricity is fairly comparable to the new Li-ion and lead acid battery system. In future, the massive inflow of used batteries from EV are expected to be available on the market for the second life application at a lower price than today. Thus, in future, second life EV batteries can become economically viable.
3

A framework for evolving grid computing systems

Alfawair, Mai January 2009 (has links)
Grid computing was born in the 1990s, when researchers were looking for a way to share expensive computing resources and experiment equipment. Grid computing is becoming increasingly popular because it promotes the sharing of distributed resources that may be heterogeneous in nature, and it enables scientists and engineering professionals to solve large scale computing problems. In reality, there are already huge numbers of grid computing facilities distributed around the world, each one having been created to serve a particular group of scientists such as weather forecasters, or a group of users such as stock markets. However, the need to extend the functionalities of current grid systems lends itself to the consideration of grid evolution. This allows the combination of many disjunct grids into a single powerful grid that can operate as one vast computational resource, as well as for grid environments to be flexible, to be able to change and to evolve. The rationale for grid evolution is the current rapid and increasing advances in both software and hardware. Evolution means adding or removing capabilities. This research defines grid evolution as adding new functions and/or equipment and removing unusable resources that affect the performance of some nodes. This thesis produces a new technique for grid evolution, allowing it to be seamless and to operate at run time. Within grid computing, evolution is an integration of software and hardware and can be of two distinct types, external and internal. Internal evolution occurs inside the grid boundary by migrating special resources such as application software from node to node inside the grid. While external evolution occurs between grids. This thesis develops a framework for grid evolution that insulates users from the complexities of grids. This framework has at its core a resource broker together with a grid monitor to cope with internal and external evolution, advance reservation, fault tolerance, the monitoring of the grid environment, increased resource utilisation and the high availability of grid resources. The starting point for the present framework of grid evolution is when the grid receives a job whose requirements do not exist on the required node which triggers grid evolution. If the grid has all the requirements scattered across its nodes, internal evolution enabling the grid to migrate the required resources to the required node in order to satisfy job requirements ensues, but if the grid does not have these resources, external evolution enables the grid either to collect them from other grids (permanent evolution) or to send the job to other grids for execution (just in time) evolution. Finally a simulation tool called (EVOSim) has been designed, developed and tested. It is written in Oracle 10g and has been used for the creation of four grids, each of which has a different setup including different nodes, application software, data and polices. Experiments were done by submitting jobs to the grid at run time, and then comparing the results and analysing the performance of those grids that use the approach of evolution with those that do not. The results of these experiments have demonstrated that these features significantly improve the performance of grid environments and provide excellent scheduling results, with a decreasing number of rejected jobs.
4

Off-grid Wind Power Systems: Planning and Decision Making

El Zein, Musadag January 2019 (has links)
There are definitely many reasons for choosing off-grid wind power systems. Few key ones involve the positive enhancement of societies, economies and natural environments. From a project developers’ perspective these systems provide a large potential market, which can cover a wide range of applications with relatively reasonable costs.  In spite of this, many challenges may interfere with the diffusion and the success of such systems. In the report we discuss the various factors affecting  the implementation of off-grid wind power systems and demonstrate some of the challenges project developers may be facing during the planning stage. Some of these include the acceptance of stakeholders (local inhabitants in particular) and the securing of the financing of the projects.  Another noted challenge lying outside the control of project developers was found to be the absence of encouraging policies and incentives. As a conclusion the thesis provides a set of self-interpreted recommendations along with a flow chart. The concluded summary indicates some key factors that project developers should be aware of and careful when dealing with, these which include: The choice of the site, verification of projects’ economics along with the securing of a convenient finance. The recommendations also point out the great advantage in having local developers as these tend to be more capable in building relations with the local citizens and politicians.
5

Encryption Key Search using Java-based ALiCE Grid

Virkar, Ameya 01 1900 (has links)
Encryption Key Search is a compute-intensive operation that consists of a brute-force search of a particular key in a given key space. Sequential execution time for a 56-bit encryption key search is approximately 200,000 years and therefore it is ideal to execute such operation in a grid environment. ALiCE (Adaptive and scaLable internet-based Computing Engine) is a grid middleware that offers a portable software technology for developing and deploying grid applications and systems. This paper discusses the development of the Encryption Key Search application on ALiCE and also presents the performance evaluation of ALiCE using this application. / Singapore-MIT Alliance (SMA)
6

JOLTS : checkpointing and coordination in grid systems

Pfeifer, Jeremy 24 August 2004
The need for increased computational power is growing faster than our ability to produce faster computers. Already researchers are proposing systems that require peta-flop capable super computers, a far cry from what is currently capable. To meet such high computational requirements, networks of computers will be required. While it is possible to network together computers to achieve a single task, making that network more flexible to handle a multitude of different tasks is the promise of grid computing. <p>Grid systems are slowly appearing that are designed to run many independent tasks, and provide the ability for programs to migrate between machines before completion. However, these systems lack coordination capabilities. Many grid systems/environments allow multiple tasks to communicate/coordinate with each other based on various paradigms, but don't provide migration capabilities. <p>This thesis proposes a system, called JOLTS, that attempts to fill a gap by providing both checkpointing and coordination capabilities. The coordination model offered by JOLTS is based on the Objective Linda coordination language, with some additions. This thesis will show that the object space model is an effective form of coordination and communication, and can effectively be combined with checkpointing capabilities inside the same grid system.
7

JOLTS : checkpointing and coordination in grid systems

Pfeifer, Jeremy 24 August 2004 (has links)
The need for increased computational power is growing faster than our ability to produce faster computers. Already researchers are proposing systems that require peta-flop capable super computers, a far cry from what is currently capable. To meet such high computational requirements, networks of computers will be required. While it is possible to network together computers to achieve a single task, making that network more flexible to handle a multitude of different tasks is the promise of grid computing. <p>Grid systems are slowly appearing that are designed to run many independent tasks, and provide the ability for programs to migrate between machines before completion. However, these systems lack coordination capabilities. Many grid systems/environments allow multiple tasks to communicate/coordinate with each other based on various paradigms, but don't provide migration capabilities. <p>This thesis proposes a system, called JOLTS, that attempts to fill a gap by providing both checkpointing and coordination capabilities. The coordination model offered by JOLTS is based on the Objective Linda coordination language, with some additions. This thesis will show that the object space model is an effective form of coordination and communication, and can effectively be combined with checkpointing capabilities inside the same grid system.
8

Optimum Design Of Double-layer Grid Systems: Comparison With Current Design Practice Using Real-life Industrial Applications

Aydincilar, Yilmaz 01 August 2010 (has links) (PDF)
Double-layer grid systems are three-dimensional pin-jointed structures, which are generally used for covering roofs having large spans. In this study, evolution strategies method is used to optimize space trusses. Evolution strategies method is a type of evolutionary algorithms, which simulate biological evolution and natural selection phenomenon to find the best solution for an optimization problem. In this method, an initial population is formed by various solutions of design problem. Then this initial population starts to evolve by using recombination, mutation, and selection operators, which are adopted for optimization of space trusses by modifying some parameters. Optimization routine continues for a certain number of generations, and best design obtained in this process is accepted as optimum solution. OFES, a design and optimization software developed for optimum design of steel frames, is modified in this study to handle space truss systems. By using this v software, six design examples taken from real-life industrial applications with element numbers changing between 792 and 4412 are studied. The structural systems defined in examples are optimized for minimum weight in accordance with design provisions imposed by Turkish Specification, TS648. The optimization is performed based on selecting member sizes and/or determining the elevation of the structure and/or setting the support conditions of the system. The results obtained are compared with those of FrameCAD, a software which is predominantly used for design of such systems in national current design practice.
9

The Mystery of the Failing Jobs: Insights from Operational Data from Two University-Wide Computing Systems

Rakesh Kumar (7039253) 14 August 2019 (has links)
Node downtime and failed jobs in a computing cluster translate into wasted resources and user dissatisfaction. Therefore understanding why nodes and jobs fail in HPC clusters is essential. This paper provides analyses of node and job failures in two university-wide computing clusters at two Tier I US research universities. We analyzed approximately 3.0M job execution data of System A and 2.2M of System B with data sources coming from accounting logs, resource usage for all primary local and remote resources (memory, IO, network), and node failure data. We observe different kinds of correlations of failures with resource usages and propose a job failure prediction model to trigger event-driven checkpointing and avoid wasted work. We provide generalizable insights for cluster management to improve reliability, such as, for some execution environments local contention dominates, while for others system-wide contention dominates.
10

Dimensionering &amp; simulering av ett PV-system för en eldriven båt / Sizing &amp; simulation of a PV-system for an electric boat

Hjalmarsson, Tobias January 2021 (has links)
Examensarbetet som presenteras i denna rapport är ett delprojekt utfört i samarbete med Glava Energy Center och redovisar framtagningen av ett PV-system för den eldrivna båten Bowter. I rapporten utfördes en energianalys där solinstrålning i olika plan studerades och analyserades. Möjligheter att utöka antalet solceller baserat på båtens design undersöktes, där båtens horisontella badbrygga samt vertikala långsidor bedömdes vara de ytor som var lämpliga för placering. Förslag på konfigurationer av PV-systemet dimensionerades och den förväntade mängden genererad energi och laddning beräknades. Systemet som togs fram skulle enligt beräkningar i genomsnitt generera mellan 1,06–2,22kWh energi per dag och kosta omkring tio tusen kronor. Energianalysen visade att solceller placerade i 30–40° lutning i genomsnitt skulle kunna generera mellan 20–43 procent mer energi och laddning än den valda vertikala placeringen. Med båtens nuvarande design utan några möjligheter för placering av solceller i lutande plan går därmed denna potentiella mängd energi förlorad. Praktiska mätningar av energi via reflektioner från vattenytan visar heller inga övertygande tecken på att rädda upp för denna mängd förlorad energi. Simuleringar av det framtagna systemet genomfördes och jämfördes med det beräknade genomsnittet, vilket visade att man skulle kunna förvänta sig cirka 25 procent mer energi under klara förhållanden och 76 procent mindre energi under svåra väderförhållanden med långvariga och heltäckande moln. Av resultaten drogs slutsatsen att det mest praktiska alternativet för maximal systemeffekt är att möjliggöra placering av fler solceller i horisontellt plan via t.ex. en takdel och på den vägen erhålla ett mer pålitligt och förutsägbart resultat som både skulle vara mer effektivt samt ekonomiskt fördelaktigt i jämförelse med det framtagna systemet. / The thesis work presented in this report is a sub-project carried out in collaboration with Glava Energy Center and reports on the development of a PV system for the electric boat Bowter. In the report, an energy analysis was performed where solar irradiance in different planes was studied and analyzed. Opportunities to increase the number of solar cells based on the boat's design were investigated, where the boat's horizontal swim platform and vertical sides were determined to be the areas that were suitable for placement. Proposals for configurations of the PV system were sized and the expected amount of generated energy and charge capacity were calculated. According to calculations the proposed system would on average generate between 1.06–2.22kWh of energy per day and cost around SEK 10,000. The energy analysis showed that solar cells placed at an angle of 30–40° could on average generate between 20–43 percent more energy and charge than the chosen vertical placement. With the boat's current design without any possibilities for placing solar cells in an inclined plane, this potential amount of energy is lost. Practical measurements of energy via reflections from the water surface show no convincing signs of compensating for this amount of lost energy. Simulations of the proposed system were carried out and compared with the calculated average, which showed that one could count on about 25 percent more energy in clear conditions and 76 percent less energy in harsh weather conditions with long-lasting and overcast clouds. From the results, it was concluded that the most practical alternative for maximum system power is to enable the placement of additional solar cells in a horizontal plane via e.g. a roof section and in that way obtain a more reliable and predictable result that would be both more efficient and economically advantageous in comparison with the proposed system.

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