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Improving the efficiency of conventional air-cooled solutions for Data Centers (DCs) is still a major thermal management challenge. Improvements can be made in two ways, through better (1) architectural design and (2) operation. There are three conventional DC cooling architectures: (a) room-based, (b) row-based, and (c) rack-based. Architectures (b) and (c) allows a modular DC design, where the ITE is within an enclosure containing a cooling unit. Due to scalability and ease of implementation, operational cost, and complexity, these modular systems have gained in popularity for many computing applications. However, the yet poor insight into their thermal management leads to limited strategies to scale the size of a DC facility for applications gaining in importance, e.g., edge and hyperscale. We improve the body of knowledge by comparing three cooling architecture’s power consumption. Energy efficiency during DC operation can be improved in two ways: (1) utilizing energy efficient control systems, (2) optimizing the arrangement of ITE. For both cases, a temperature prediction tool is required which can provide real-time information about the temperature distribution as a function of system parameters and the ITE arrangement. To construct such a prediction tool, we must develop a deeper understanding of the airflow, pressure and temperature distributions around the ITE and how these parameters change dynamically with IT load. As yet primitive tools have been developed, but only for architecture (a) listed above. These tools are not transferrable to other architectures due to significant differences in thermal-fluid transport. We examine the airflow and thermal transport within confined racks with separated cold and hot chambers that employ rack- or row-based cooling units, and then propose a parameter-free transient zonal model to obtain the real-time temperature distributions. / Thesis / Doctor of Philosophy (PhD)

“It would be something if everything we made encouraged people to become more closely acquainted with their surroundings, with each other and with themselves… so that the world, in so far as it is amenable to our influence, becomes less alien, less hard and abstract, a warmer, friendlier, more welcoming and appropriate place; in short a world that is relevant to its inhabitants.” Herman Hertzberger The purpose of this thesis is to create a mixed income housing community in Old Town Alexandria. While people who share similar lifestyles tend to cluster together, this project encourages people of difference to find a common ground. The community will be the size of a residential Old Town block to encourage a fulfilling amount of human interaction. The interior of the block will be subdivided into a variety of places: places that provide the opportunity for people to sit in quiet contemplation, another place for children to play, other places that encourage people to interact with one another, and places where one can passively observe the surrounding activity with the option to participate or not. The houses have a variety of living spaces in response to the diverse social groups that will inhabit the blocks. These houses follow the language of Old Town in terms of materials, details, rhythm, and the way in which they meet the street, and so connect this community with the larger order of the town. This project maintains the privacy of the individual houses, encourages human interaction in the public areas, and at the same time recognizes the responsibility of designing these houses using the same structure and patterns that are inherent in Old Town. / Master of Architecture

<i>Mortal Limit by Robert Penn Warren I saw the hawk ride updraft in the sunset over Wyoming. It rose from coniferous darkness, past gray jags Of mercilessness, past whiteness, into the gloaming Of dream spectral light above the last purity of snow-snags. There-west-were the Tetons. Snow peaks would soon be In dark profile to break constellations. Beyond what height Hands now the black spec? Beyond what range will gold eyes see New ranges rise to mark a last scrawl of light? Or, having tasted that atmosphere’s thinness, does it Hang motionless in dying vision before It knows it will accept the mortal limit, And swing into the great circular downwardness that will restore The breath of earth? Of rock? Of rot? Of other such Items, and the darkness of whatever dream we clutch?</i> This is an endeavour in learning about architecture. The project, a competition on Charles Bulfinch’s Old Jail Site in Old Town Alexandria, to make Townhouses, serves as a vehicle towards that end. / Master of Architecture

The imposition of boundary at many scales is an essential part of Architecture. Boundaries define enclosure. An architectural philosophy must control these boundaries. / Master of Architecture

Sustainable vegetable production is one of the most active areas of vegetable research and of concern to all producers. Everyone, both producers and consumers, are concerned with sustainability. Brussels sprouts and sweet basil are high value commodities, but increasing global concerns about water availability, insect-pest problems, and costly fertilizer inputs severely impact the growth and production of these crops. Low tunnels covered with spun-bonded fabric can improve production of vegetables and herbs in Virginia and the U.S. This study investigated the performance of Brussels sprouts and basil grown under low tunnels (LTs), and their relationship with water use efficiency, nitrogen use efficiency, and the level of protection against insect injury. Low tunnels increased yield, number of sprouts, and water use efficiency of Brussels sprout production. In addition, LTs decreased irrigation requirements, irrigation events, leaf feeding injury, and insect populations in comparison to open field. Similarly, LTs increased summer production of sweet basil as measured by fresh weight and biomass. In addition, plant N uptake was greater under the LTs; however, the increase in nitrogen use efficiency was inconsistent. / Master of Science in Life Sciences / Brussels sprouts and sweet basil are economically important cash crops on the East Coast. Brussels sprouts is a Cole crop and an important source of dietary fiber, vitamins (A, C & K), calcium, iron, manganese and antioxidants. Similarly, sweet basil is a member of the mint family and important high-value herb in the U.S. and the world. It is mainly grown for culinary purposes as a dried and fresh spice in the U.S. However, demand for these commodities is increasing. Low tunnels (LTs) covered with spunbonded fabric can be a practical management tool to increase yield. Results from this study indicate that LTs increase yield of Brussels sprouts and basil, water use efficiency and total nitrogen uptake, while reducing insect pest infestation. Therefore, LTs can be a useful tool to improve sustainability of Brussels sprouts and basil production.

Property Management, one functional area within Right-of-Way offices in state transportation agencies, is responsible for managing the property acquired for highway projects. These activities are data and document intensive and efficiency for performing them would be improved through the implementation of an information management system. Because of the geospatial nature of many of these activities, geographic information systems (GIS) would increase the effectiveness of this system. A literature review and survey were conducted to understand the current state of practice for the use of GIS and information management systems in Property Management. There is no identified comprehensive system that covers all Property Management activities. An initial step in developing a geospatially-enabled enterprise-level information management system, a logical model was developed. This included developing the business process diagram, business process models, and use case models based on the principles of systems engineering using the Computer Aided Software (CASE) Enterprise Architecture. Activities that would benefit from a geospatial component have been identified and included in the models. The developed models have been validated by working with PennDOT staff. The resulting model serves as a standard template for state transportation agencies and helps conceptualize the advantages of integration and interaction with other systems, and geospatial enablement prior to investment in an information management system. / Master of Science

For over a century, the railway system has been gradually designed and adapted to serve the corresponding demands under variations of given budgets. However, recent developments indicate that the railway systems of many European countries gradually come to their limits, as the national infrastructure managers declare an increasing share of their network tracks as congested. Consequently, the capabilities of each railway system are getting more into focus, to adequately serve the recent intention of shifting more demand to rail to encounter climate change. The system’s capacity is thereby of particular interest, i. e. whether the system already has the ability to serve increasing traffic loads by leveraging existing reserves, or otherwise needs significant extensions to serve the increasing demand. We thus need to quantify the current capacity of the railway system to identify its current capabilities and to deduct corresponding measures to leverage capacity reserves and relieve saturated network parts. Only the appropriate measure selection, i.e. deciding where to apply traffic reorganization and optimization or infrastructural extensions and restructuring, allows to achieve the goal of shifting more demand to rail under limited resource constraints. The main contributions of this thesis are in the design, optimization and application of a network capacity assessment approach for large-scale railway networks, which incorporates the perspectives of infrastructure, operations and demand by using the number of trains per time window and scheduled waiting times as capacity metric. Hence, this thesis provides a new definition of network capacity, and develops petri net (PN)-based capacity assessment models for railway networks with the use of mixed integer program (MIP) and row generation. The capacity is then determined by assessing the maximum utilization and the scheduled waiting times of the railway network with respect to infrastructure, railway operations and demand. We first introduce the definition of railway network capacity, which extends the concept of railway capacity from stations and corridors to entire networks. This new utilization-based and demand-centric definition of practical railway network capacity defines railway network capacity as the maximum number of departing trains in the network over a given time period, regarding the given infrastructure, operations and demand. This definition allows to accurately determine the interplay of infrastructure, operations and demand, with a combined measure of traffic flow and scheduled waiting times. In the context of this new definition on network capacity, different assessment approaches for the capacity of railway stations, corridors and networks are reviewed with regard to their spatial scope, the used approach and the applied capacity metric. Second we propose the railway network utilization model (RNUM), which extends an existing PN based approach from single line to entire network operations. This model builds upon individual lines, which are then connected to more complex structures. The analysis of the maximum utilization is based on the network’s elementary circuits. Furthermore, token modifications are introduced to characterize relevant process circuits and introduce interline separation places to model and assess complex networks. By additionally considering rolling stock circulations and imposed train orders, the utilization is determined for given operation scenarios of a line system, which operates at heterogeneous frequencies. The resulting timetable independent approach allows to fully characterize the utilization of the network. To assess the network capacity, an enumeration-based railway network capacity (RNC) framework is further introduced, which evaluates the maximum utilization over diverse operation scenarios to represent possible network demands. The resulting train flows as well as the average scheduled waiting times per train, the capacity and the corresponding network effects were finally quantified and determined in network-specific macroscopic fundamental diagram for the railway network (MFD-R). Third, we introduce the railway network utilization MIP model (MIP-RNUM) to determine the optimal capacity utilization by combining PNs with mathematical linear programming. The presented model is enabled to simultaneously assess different train locations and line orders to provide the network’s utilization, capacity-optimal train locations and line orders for given operation scenarios. The MIP-RNUM is further improved to provide the demand-centered capacity utilization, by incorporating extended demand structures, which capture the demanded flows and magnitudes as fixed proportions of trains per line. The additional incorporation of local routing and thus optimal line orders in the utilization assessment, extend the model further to provide the optimal and demand-centered capacity utilization without the correspondingly required enumeration of different line orders. The resulting fully extended MIP-RNUM comprehensively captures the interplay of infrastructure, railway operations and demand; and the resulting effects on the network capacity. Fourth, we propose the row generation MIP-RNUM (MIP-RNUM-RG) to assess the capacity of large-scale instances. The proposed approach tackles the computationally intensive enumeration of the network’s cycles of the RNUM by applying lazy-constraint generation i.e. iteratively adding violated constraints of previous solutions to the problem in a row generating manner. To assess the solution quality of intermediate solutions during the capacity assessment of large instances, a lower-bound method is presented, which combines a higher order max-plus system and a binary search algorithm. The lower-bound method allows to check the feasibility of a given solution and to quantify the optimality gap of the current results while solving the MIP-RNUM-RG. In summary, this thesis provides multiple scientific contributions to efficiently assess the capacity of complex railway networks by developing several assessment models and frameworks. By integrating the different perspectives of infrastructure, operations and demand, this thesis supports network design towards the development of demand-centric railway systems. Regarding the intended growth of the railway demand in the near future, this thesis can guide practitioners to assess the capabilities of our present railway systems and derive the necessary actions to transform them into the transport systems of our future. / Das Eisenbahnsystem wurde über ein Jahrhundert lang entworfen und angepasst, um die jeweilige Nachfrage unter einem sich verändernden Budget zu bedienen. Aktuelle Entwicklungen zeigen jedoch, dass die Eisenbahnsysteme vieler europäischer Länder allmählich an ihre Grenzen stoßen. Zeitgleich geraten die Fähigkeiten eines jeden Eisenbahnsystems in den Fokus, mit denen zur Begegnung des Klimawandels mehr Verkehr auf die Schiene verlagert werden kann. Die Systemkapazität ist dabei von besonderem Interesse, d. h. ob das System bereits in der Lage ist, wachsende Verkehrsmengen durch die Nutzung existierender Reserven zu bewältigen, oder ob es zur Bedienung der steigenden Nachfrage einen deutlichen Ausbau braucht. Aus diesem Grund muss die Kapazität des Eisenbahnsystems bewertet werden, um damit seine aktuellen Möglichkeiten zu identifizieren und durch entsprechend abgeleitete Maßnahmen Kapazitätsreserven nutzbar zu machen und saturierte Netzteile zu entlasten. Der wesentliche Beitrag dieser Arbeit liegt im Entwurf, der Erweiterung und Anwendung eines Ansatzes zur Untersuchung der Netzwerkkapazität für großräumige Eisenbahnnetze unter Einbeziehung der Einflussfaktoren Infrastruktur, Betrieb und Nachfrage. Als Kapazitätsmetrik kommen dabei die Zugzahlen pro Zeiteinheit und die planmäßigen Wartezeiten zum Einsatz. Diese Arbeit entwirft dafür eine neue Definition der Netzwerkkapazität und entwickelt anschließend Petri-Netz (PN) basierte Untersuchungsmodelle für die Eisenbahnnetzkapazität unter Nutzung von gemischt-ganzzahliger Programmierung und Zeilengenerierung (eng. row generation). Durch die Analyse der maximalen Kapazitätsausnutzung und der planmäßigen Wartezeiten im Netz wird die Kapazität unter Berücksichtigung der Einflussfaktoren bestimmt. Zuerst wird die Definition der Eisenbahnnetzwerkkapazität eingeführt, die das Konzept der Eisenbahnkapazität von Bahnhöfen und Streckenkorridoren auf Netzwerke erweitert. Diese neue, auf Kapazitätsausnutzung basierende, nachfragezentrierte Definition der praktischen Eisenbahnnetzwerkkapazität definiert die Netzkapazität als die maximale Anzahl der im Netzwerk abfahrenden Züge innerhalb eines gegebenen Zeitintervalls, unter Berücksichtigung der gegebenen Einflussfaktoren. Im Kontext dieser neuen Definition werden verschiedene, existierende Untersuchungsansätze für die Kapazität von Eisenbahnknoten, Streckenkorridoren und Netzwerken rezensiert. Die Ansätze werden insbesondere hinsichtlich ihres räumlichen Umfangs, des angewendeten Verfahrens und der jeweils genutzten Kapazitätsmetrik verglichen. Als Zweites wird das Eisenbahnnetzwerkausnutzungsmodell (eng. railway network utilization model – RNUM) präsentiert, das einen existierenden PN-Ansatz von einer einzelnen Linie auf Netzwerke erweitert. Dieses Modell setzt sich aus einzelnen Linien zusammen, die zu komplexeren Strukturen zusammengesetzt werden. Die Analyse der maximalen Kapazitätsausnutzung basiert auf den Elementarkreisen des entstehenden Netzwerks. Durch die zusätzliche Berücksichtigung von Fahrzeugumläufen und vorgegebenen Zugfolgen wird die Kapazitätsausnutzung für gegebene Betriebsszenarien eines Liniensystems bestimmt, in welchem die Linien mit heterogenen Taktzeiten verkehren. Der resultierende, fahrplanunabhängige Ansatz erlaubt die vollständige Charakterisierung der maximalen Kapazitätsausnutzung unter Berücksichtigung diverser Betriebsszenarien. Die resultierenden Zugverkehrsströme und die mittleren planmäßigen Wartezeiten pro Zug, die ermittelte Kapazität und die zugehörigen Netzwerkeffekte werden schließlich in einem netzwerkspezifischen makroskopischen Fundamentaldiagram für Eisenbahnnetzwerke (MFD-R) bestimmt. Als Drittes wird das Eisenbahnnetzwerkausnutzungs-MIP-modell (MIP-RNUM) eingeführt, um die optimale Kapazitätsausnutzung durch eine Kombination von PN und linearer Programmierung zu bestimmen. Das eingeführte Modell kann simultan verschiedene Zugpositionen und Zugfolgen berücksichtigen, um auf deren Grundlage die Netzwerkausnutzung, kapazitätsoptimale Zugpositionen und -folgen für gegebene Betriebsszenarien zu untersuchen. Im Folgenden wird das MIP-RNUM erweitert, um die nachfragezentrierte Kapazitätsausnutzung zu erfassen. Die zusätzliche Berücksichtigung von variablen Fahrwegen in Knoten und den zugehörigen optimalen Zugfolgen in der Ausnutzungsuntersuchung ergänzen das Modell zusätzlich, um die optimale und nachfragezentrierte Kapazitätsausnutzung ohne die bisher benötigte Enumeration der Zugfolgen zu ermitteln. Das resultierende erweiterte MIP-RNUM erfasst das Zusammenspiel von Infrastruktur, Eisenbahnbetrieb und Nachfrage und deren umfassende Auswirkungen auf die Netzwerkkapazität. Zuletzt wird das zeilengenerierende MIP-RNUM (MIP-RNUM-RG) vorgestellt, um auch die Kapazität großräumiger Instanzen untersuchen zu können. Der vorgestellte Ansatz begegnet der rechenzeitintensiven Enumeration der Elementarkreise des RNUM mit einer sog. lazy constraint generation, d. h. der iterativen, zeilengenerierenden Ergänzung verletzter Nebenbedingungen zum Problem. Um bei der Untersuchung großräumiger Instanzen die Lösungsqualität der jeweiligen Zwischenergebnisse beurteilen zu können, wird eine untere Schranke vorgestellt, die ein max-plus System höherer Ordnung mit einem binären Suchalgorithmus kombiniert. Diese untere Schranke ermöglicht die Zulässigkeitsprüfung einer gegebenen Lösung und darüber hinaus die Quantifizierung der Optimalitätslücke der aktuellen Ergebnisse. Damit stellt diese Arbeit verschiedene wissenschaftliche Beiträge in Form unterschiedlicher Untersuchungsmodelle und -methoden bereit, um die Kapazität komplexer Eisenbahnnetzwerke zu untersuchen. Dabei werden die verschiedenen infrastrukturellen, betrieblichen und nachfragespezifischen Perspektiven integriert betrachtet, um die nachfragezentrierte Netzentwicklung von Eisenbahnsystemen zu unterstützen. Unter Berücksichtigung des Wachstums der Eisenbahnnachfrage in naher Zukunft kann diese Arbeit so Planer*innen helfen, die Fähigkeiten unserer gegenwärtigen Eisenbahnsysteme zu untersuchen und daraus die nötigen Handlungsalternativen abzuleiten, um die Verkehrssysteme unserer Zukunft zu entwickeln.

Thesis (PhD(Agric) (Agronomy))--Stellenbosch University, 2008. / The adoption of the no-till planting method brought about changes to the way the wheat crop is established in the Mediterranean climate of the Western Cape. Row widths have to increase from the normal narrow rows (170-180 mm) to at least 250 mm to allow for sufficient stubble handling. Furthermore, planters are designed to place seed accurately in the soil at uniform depth, which may increase seedling survival rates. The main objective of this study was to determine the influence of the use of wide row widths on yield, the components of yield and grain quality parameters and to revisit planting density recommendations to be used with the notill planting method. On-farm, producer managed trials which included cultivars, row widths and planting density treatments were planted at Riversdale, Swellendam and Caledon in the Southern Cape region and at Moorreesburg and Hopefield in the Swartland during the 2004 to 2006 production seasons. All trials were factorial RCB designs with split-split plot arrangements. Grain yield, grain protein, hectolitre mass (HLM) and the yield components, seedlings m-2, seedling survival (%), number of heads m-2, number of heads plant-1, number of kernels head-1 and thousand kernel mass (TKM) were determined at all sites in 2005 and 2006. Seedling survival rates of 80% were easily achieved in all trials with the exception of Caledon and Swellendam in 2005. The no-till planting method may be efficient to improve on survival rates of 50-70% found with the conventional planting methods. The yield component response that raised the most concern was the clear trend of the reduction in the number of heads m-2 as row widths increased, which was significant in eight out of the nine experiments. The number of heads plant-1 decreased significantly as planting density increased in all experiments. Cultivars differed in the grain quality parameters grain protein (%) and HLM but were influenced minimally by the other treatments. Reductions in grain yield occurred in three out of eight trials in the Southern Cape and in three out of six trials in the Swartland, with reductions of between 6.8% and 33% in some seasons. The risk of yield loss due to wide row widths could not be excluded by this study and therefore the row widths used by producers should remain as narrow as practically possible. Grain yield response to increasing planting density differed between the two regions. No significant yield benefits were found in any of these trials if planting densities were increased above 175 target plants m-2. Planting densities may be reduced to between 70 and 87.5 kg seed ha-1 to achieve this target if the crop is planted in time and seedling survival rates of at least 80% can be achieved.

John Steinbeck's three novels Tortilla Flat, Cannr Row and Sweet Thursday are significant in the Steinbeck canon. Although having many elements typical of Steinbeck's fiction in general, these novels, which are referred to as the Monterey Trilogy, are unified by common elements that are either unique or handled in an unusual manner. These common elements are setting, tone, themes, structure, and characters. The novels are complementary and form a unified whole. Just as the setting reflects the evolution of Monterey over a period of almost thirty years, so do the other elements reveal a shift in emphasis or attitude indicative of Steinbeck's own changing attitudes. The concluding chapter discusses the particular significance of the Monterey Trilogy as a measure of Steinbeck's ability as artist and craftsman.