Multi-material structures (MMSs) are attractive due to their unique advantages in achieving tailored properties at different locations in a single part. Producing such structures by additive manufacturing has been gaining more and more attention because of the beneficial characteristics of additive manufacturing processes such as its ability in building complex geometries, shortening producing chains, and most importantly, easily integrating with multi-material feeding systems. This PhD thesis investigates the potential of MMSs fabricated by directed energy deposition (DED) using tool steel and copper alloy. Specifically, AISI H13 hot work tool steel is deposited on copper-beryllium alloy (CuBe) substrate using three deposition strategies: directly depositing H13 on CuBe (H13/CuBe), SS316L buffer (H13/SS316L/CuBe), and commercially pure nickel buffer (H13/Ni/CuBe), aiming to minimize cracking issues. The morphology of single-track, single-layer, and multi-layer specimens is analyzed. The microstructure of deposited specimens is also investigated, along with its mechanical and thermal properties, such as microhardness, wear resistance, load-bearing capability (LBC), and thermal conductivity. The results show that directly depositing H13 on CuBe cannot avoid cracking in the H13 layers while preheating the CuBe substrate at 150°C and 250°C reduces the cracking tendency but damages the strength of the CuBe substrate due to over-aging while introducing difficulty to manage processing procedure. Using SS316L buffer can suppress the crack extension in H13 cladding due to a barrier mechanism, i.e., its ability to reduce the Cu penetration into H13 layers. However, SS316L itself is prone to cracking when directly deposited on the CuBe substrate as a buffer layer. Through analysis of cracking morphology, parameter effects, and element distribution, it was possible to identify solidification cracking as the primary cracking mechanism in all specimens. Two metallurgical factors, solidification temperature range and amount of terminal liquid, were found to dominate the cracking tendency. The introduction of Cu into steel can significantly extend the solidification temperature range, thereby increasing the susceptibility to cracking. However, as the Cu composition continuously increases, the cracking susceptibility decreases due to the backfilling of the terminal liquid into cracks resulting in a healing effect. The solidification paths of the Fe-Cu binary system were calculated as a function of Cu composition. Using this data, a map was generated reporting the solidification temperature range and terminal liquid amount as a function of Cu composition for the Fe-Cu binary system. Even if only to a first approximation (the effect of alloying elements in both, steel and CuBe alloy), this map can be used as a tool to estimate the cracking susceptibility of steel/copper alloy MMSs deposited by DED. The experimental results are in good agreement with thermodynamic calculations. Based on this analysis, a pure nickel buffer strategy was selected and proved to be effective in minimizing the cracking issue in H13 due to the narrow solidification temperature range of Ni-Cu and Ni-Fe binary systems induced the high solubility of Ni in Fe and Cu. By employing this strategy, crack-free specimens were produced. The high hardness of the H13 single-layer cladding, with an average value of 740 HV, provided a significant improvement in wear resistance compared to the CuBe (400 HV). However, in multi-layer specimens, a gradual decrease in microhardness of H13 cladding from the outer to the inner layers was observed due to the mixing of remelted soft buffer materials into H13 and the in-situ tempering effect in the previous deposited H13 layers. The above result, further confirms that the load-bearing capability (LBC) cannot be infinitely improved by adding more H13 layers. In general, in the low loading range (From 5 to 10 kN), the LBC of MMS specimens was higher than the CuBe due to the higher hardness of outer H13 layers. However, it became lower in the high loading range due to the presence of soft sublayer materials such as softened martensite, soft buffer layers (H316L = 260 HV or HNi = 130 HV), and the heat-affected zones in the CuBe substrate. The thermal conductivity of MMS specimens first drops rapidly to half of the original value as the cladding thickness ratio (tcladding/tCuBe) increases from 0 to around 20%. After that, the decrease becomes slower, with a further reduction of around 37% in thermal conductivity as the cladding thickness ratio increases from 20% up to 50%. Therefore, a tradeoff between mechanical and thermal properties must be considered looking for the application of these cladding systems. A proper cladding thickness ratio of around 20% is recommended to achieve reasonably high strength while still maintaining thermal conductivity at an acceptable level. Overall, these findings have important implications for the selection of appropriate materials and processing parameters to optimize the mechanical and thermal properties of tool steel/copper alloy MMSs deposited by DED.

This dissertation presents a Field Programmable Gate Array (FPGA) design methodology that can be used to shorten the FPGA design-and-debug cycle, especially as gate counts increase to many millions. Core-based incremental placement algorithms, in conjunction with fast interactive routing, are investigated to reduce the design processing time by distinguishing the changes between design iterations and reprocessing only the changed blocks without affecting the remaining part of the design. Different from other incremental placement algorithms, this tool provides the function not only to handle small modifications; it can also incrementally place a large design from scratch at a rapid rate. Incremental approaches are inherently greedy techniques, but when combined with a background refinement thread, the incremental approach offers the instant gratification that designers expect, while preserving the fidelity attained through batch-oriented programs. An incremental FPGA design tool has been developed, based on the incremental placement algorithm and its background refiner. Design applications with logical gate sizes varying from tens of thousands to approximately one million are built to evaluate the execution of the algorithms and the design tool. The results show that this incremental design tool is two orders of magnitude faster than the competing approaches such as the Xilinx M3 tools without sacrificing much quality. The tool presented places designs at the speed of 700,000 system gates per second. The fast processing speed and user-interactive property make the incremental design tool potentially useful for prototype developing, system debugging and modular testing in million-gate FPGA designs. / Ph. D.

The purpose of this study was to understand the teaching practices of the Agriculture Faculty at Bangladesh Agricultural University (BAU). This study is at the intersection of the critical assessment and examination of assumption and exploring options and plans stages of transformative learning theory (Mezirow, 2000) and the environment factor of Astin's I-E-O model. Previous studies showed that tertiary education of Bangladesh fails to develop critical thinking abilities among the students. Higher order teaching practices help to develop critical thinking abilities among the students. Thus, it is important to explore the level of teaching practices at the Agriculture Faculty of BAU to understand how it supports critical thinking abilities among the students. Graduates being able to use critical thinking skills to solve agricultural issues will increase total food production and reduce national poverty. This study was an instrumental single case study. Faculty of Agriculture of BAU was the unit of analysis for this study. The findings of this study were only generalizable to the Agriculture Faculty at BAU and only relevant for Summer 2020. The phenomenon of this study was teaching practices at the Agriculture Faculty of BAU. Data sources included a census survey of active faculty members and content analysis of course syllabi. Findings from this study suggested that both teaching methods and course learning outcomes of the courses of the Agriculture Faculty at BAU were related the lower order of Revised Bloom's Taxonomy (RevBT). Moreover, faculty members from biological science and engineering used more teaching practices from evaluating level of RevBT than social science disciplines. Evaluating level is considered as higher level of RevBT. Male faculty members also used more teaching practices related to analyzing level than female faculty members. Analyzing level is also considered as higher level of RevBT. Faculty members identified that they have lack of training, standard teaching resources to use higher order teaching practices. Moreover, they also said that students of the Agriculture Faculty at BAU are more interested in job preparation than classroom education. However, faculty members also felt that higher order teaching practices can improve the creativity and critical thinking abilities for students and brings enthusiasms in teaching. Faculty members recommended that BAU revise its curriculum, syllabi, and assessment strategies to create higher order teaching practices in classrooms. As a result of this study, there is opportunity for faculty to increase their use of higher order teaching practices and develop course outcomes that support higher order learning. In addition, the university should revise their existing curricula and assessment techniques and give more freedom to the faculty members to choose their teaching and assessment methods. Finally, training should be organized to support higher order teaching by female faculty members. / Doctor of Philosophy / The purpose of this case study was to understand the teaching practices of the Agriculture Faculty at Bangladesh Agricultural University (BAU). Conceptually, this study was coupled up with transformative learning theory (Mezirow, 2000) and the Astin's I-E-O model. The unit of analysis of this study was the educational environment provided by Agriculture faculty of BAU that offers a single under-graduate degree program called B.Sc. Ag. (Hons.). A structured survey questionnaire was used to collect data from the faculty members of the Agriculture Faculty of BAU based on Revised Bloom's Taxonomy (RevBT). Additionally, all course syllabi were analyzed to identify the level of intended teaching practices based on RevBT. RevBT is the benchmark standard to evaluate the cognitive orders of the teaching-learning process, curriculum planning, instruction, and test tasks. Findings from this study suggested that faculty members slightly more preferred teaching practices from the lower levels of RevBT for the classroom teaching at BAU. Findings also suggested that teaching practices connected to the higher cognitive levels of RevBT were significantly varied based on academic disciplines and gender of the faculty members. Faculty members mentioned that lack of students' interest in classroom lessons, the rigid curricula and existing examination system of BAU, large numbers of students in classes, and lack of training of the faculty members are the main limiting factors for them to use higher order teaching practices in classrooms. However, faculty members also wanted to use the higher order teaching practices in classrooms as higher order teaching practices enhances students' creativity, problem solving skills, and critical thinking skills. Faculty members suggested to update course curricula, syllabi, and the exam system to support higher-order teaching practices at BAU. Findings from the course syllabi analysis supported that most of the action verbs of course learning outcomes of the course syllabi were connected to the lower cognitive levels of RevBT. As a result of this study, there is opportunity for faculty to increase their use of higher order teaching practices and develop courses that support higher order learning. In addition, the university should revise their existing curricula and assessment techniques and give more freedom to the faculty members to choose their teaching and assessment methods. Finally, training should be organized to support higher order teaching by female faculty members.

One substantial vision of maintaining agricultural productivity and sustainability is to improve farmers' and communities' well-being and quality of life. Offering disability-inclusive programs can ideally improve agricultural producers' social, environmental, and economic conditions. In turn, it has the potential to accelerate efforts to achieve social justice across varied environments and contexts. Thus, the study explored AgrAbility as an agricultural assistance program serving people with disabilities. A mixed-method approach (survey and interview) was employed to (1) explore and aggregate frameworks used by different State and Regional AgrAbility Projects (SRAP) for planning assistance programs, (2) examine the common types of evaluations used for assessing AgrAbility program impact, and (3) identify good practices for maximizing self-report tools' usability in program evaluation. Sixteen AgrAbility states were included in this study (Iowa, West Virginia, Alaska, California, Colorado, Kansas, Maine, Missouri, Nebraska, North Carolina, Pennsylvania, South Dakota, Tennessee, Texas, Virginia, and Wisconsin). Two states (Iowa and West Virginia) represent affiliated projects; the other states represent state/national projects. The planning survey was completed by 16 respondents, followed by interviews with 7 of them. The evaluation survey was completed by 11 respondents, followed by interviews with 7 AgrAbility participants (i.e., clients). Three integrated planning models (the Targeting Outcomes of Programs [TOP] model, Sork's planning domains, and Cervero and Wilson's planning model) were used as a conceptual framework to guide the study questions. The study findings offered a framework that could serve as a guideline to answer the following question: "To what extent is the ethical and social-political domain (i.e., power, interests, negotiation, and responsibilities) addressed or enacted within planning programs serving people with disabilities?" Also, the study findings revealed that self-report tools are very frequently used in evaluating AgrAbility outcomes. Ten recommendations were shared by AgrAbility evaluators and program participants with disabilities to improve self-report tools' usability and response rates, specifically in the disability context. / Doctor of Philosophy / Disability has profound effects on farm households. Agricultural workers with disabilities need adequate assistance programs to help them be productive and motivated and feel safe and independent while performing their work. Also, establishing disability-inclusive assistance programs can improve social, environmental, and economic conditions. In turn, these programs have the potential to accelerate efforts to achieve social justice. I explored AgrAbility as an agricultural assistance program serving people with disabilities. I sought to understand AgrAbility's practical implications for enhancing rural well-being and, in turn, seeking social justice. Sixteen AgrAbility states were included in this study (Iowa, West Virginia, Alaska, California, Colorado, Kansas, Maine, Missouri, Nebraska, North Carolina, Pennsylvania, South Dakota, Tennessee, Texas, Virginia, and Wisconsin). They completed a survey asking questions about technical approaches to program planning, followed by interviews with 7. However, only 11 AgrAbility states completed the survey focused on some evaluation questions, followed by interviews with 7 AgrAbility participants with disabilities (i.e., clients). The purpose of the study was to (1) explore and aggregate frameworks used by different State and Regional AgrAbility Projects (SRAP) for planning assistance programs, (2) examine the common types of evaluations used for assessing AgrAbility program impact, and (3) identify good practices for maximizing self-report tools' usability in program evaluation. I came up with a framework that could serve as a guideline to answer the following question "To what extent is the ethical and social-political domain (i.e., power, interests, negotiation, and responsibilities) addressed or enacted within planning programs serving people with disabilities?" Also, the study findings showed that self-report tools are very frequently used in evaluating AgrAbility outcomes. Ten recommendations were shared by AgrAbility evaluators and program participants with disabilities to improve self-report tools' usability and response rates, specifically in the disability context.

Climate services, often refers as decision support tools, are developed to provide information with a view to aid in decision making and policy planning for adaptation due to climate variability and change. This study investigated different publicly available climate services and decision support tools based on previously proposed evaluation framework. This evaluation framework originally consists of four design elements which are divided into nine evaluation metrics for this study. These evaluation metrics are: identification of decision making context, discussion of the role of climate information in decision making, discussion of non-climatic factors, uncertainty of the data presented, accessibility of information, discussion on the development process, sustainability/ ongoing process, discussion of funding sources, and evaluation of the tool through survey, modeling or contingent valuation method. Tools were then given "High", "Medium", and "Low" score for each of the criterion. A total of 19 tools were evaluation for this study. Tools performed relatively well in "characteristics, tailoring, and communication of the climate information" and "governance, process, and structure of the climate service" whereas they got average scores in "problem identification and the decision-making context" and "value of the service provided". Additionally, four case study evaluation of tools showed detail evaluation of how the tools performed against each of the criterion. The results of this study showed the relative strengths and weakness of the evaluated tools which can be used to improve existing climate services to aid in adaptation decision needs for climate change. This will also help in better decision making and policy planning for different sectors impacted by the changing climate. / Master of Science / Climate services, often refers as decision support tools, are developed to provide information with a view to aid in decision making and policy planning for adaptation due to the adverse impacts caused by climate variability and change. This study investigated a total of 19 publicly available climate services and decision support tools based on previously proposed evaluation framework. This evaluation framework originally consists of four design elements which further classified into nine evaluation metrics and each of tools were given "High", "Medium", and "Low" score against these criteria. These metrics are: identification of decision making context, discussion of the role of climate information in decision making, discussion of non-climatic factors, uncertainty of the data presented, accessibility of information, discussion on the development process, sustainability/ ongoing process, discussion of funding sources, and evaluation of the tool through survey, modeling or contingent valuation method. Evaluated tools performed better than average in terms of uncertainty of the data presented, accessibility of information, discussion on the development process, sustainability/ ongoing process, discussion of funding sources, and feedback/ evaluation criteria whereas they performed below average in problem identification and decision making context, discussion of the role of climate information in decision making, and discussion of non-climatic factors. Four case study evaluation were also presented in this study for better understanding of how the evaluation process works for the tools. The results of this study provide an insight about the relative strengths and weakness of the evaluated tools and these can be used to improve existing climate services tools. This will also help in better decision making and policy planning for different sectors that are being impacted by the changing climate.

Usability evaluation results in several usability problems and the non-UE developer is often not a part of the evaluation as it might deter the participant from reporting all the errors and also, conducting usability evaluation is a usability engineer's responsibility. Thus the evaluator needs to create unambiguous usability problem reports, which will help the developer fix the usability problems. This research involves the development and evaluation of the Usability Problem Diagnosis tool, which supports problem diagnosis through analysis and storage in a common database shared between the evaluation and the development team. This tool uses the User Action Framework as an underlying knowledge base to support problem diagnosis. / Master of Science

A two-part project was used to study the idea of demonstration in architecture. The first was the design and fabrication of cycloidal drawing tools. The second was the design of another studio building for the College of Architecture and Urban Studies at Virginia Tech. First, the study of cycloidal lines became the catalyst for designing and fabricating cycloidal drawing tools. Drawing a cylcoid is a demonstration of its construction. There are no specialized tools available for drawing these types of lines, so several iterative generations of design were needed to refine the form of the tool and reach adequate accuracy. Second, an additional studio building for the College of Architecture and Urban Studies at Virginia Tech was designed. It was designed to be a place for the demonstration of craftsmanship. The building was placed adjacent to Cowgill Hall. The form of the building was explored through traditional tools of architectural design, namely drawings of plans, sections, elevations and details. For the best representation of this thesis, please refer to the book found in the Art and Architecture library. / Master of Architecture

Identifying and articulating a research topic and related problems are important processes for novice researchers. However, some novice researchers have trouble in these processes due to their low domain knowledge, low structural knowledge, insufficient metacognition, or insufficient information access skills. This study addressed these problems by developing an information base tool using strategies and tools investigated by previous studies. The tool includes conceptual modeling, guided search, experimental variables and relationships examination, note-taking, suggestion, file import, and review features. The tool was populated with relevant information to permit testing and formative evaluation by novice researchers. Expert reviewers evaluated the effects of each feature of the tool on scaffolding individuals who have low domain knowledge or low structural knowledge and supplementing individuals who have insufficient metacognition or insufficient information access skills. The reviewers commonly agreed that specific components of the tool would be effective in scaffolding individuals who have low domain knowledge or low structural knowledge, or supplementing individuals who have insufficient information access skills. / Ph. D.

Microalgae are photosynthetic organisms considered to be one of the most promising high-value chemicals and biofuel-producing organisms. However, there are several challenges for the widespread implementation of industrial processes using microalgae. The work presented in this dissertation proposes solutions to the different challenges involving the use of microalgae as microbial cell factories. To investigate the application of anaerobic digestion as a way to generate nutrients for microbial growth, salmon offal was used as substrate for anaerobic digestion, and soil from a flooded run-off pond on the Virginia Tech campus in Blacksburg, VA. A fast reduction in volatile solids and the short-chain fatty acid production profile is favorable for the growth of microalgae. A novel algae strain Scenedesmus sp. A6 was isolated from a decorative waterfountain in a hotel in Madison, IN. Mixotrophic growth trials were conducted using wastewater from the salmon offal digestion, that demostrated the A6 isolate grows six times faster in the wastewater then autotrophically. Bioassays of ethanolic cell extracts of A6 cultures demonstrated antimicrobial activity against E. coli cells at concentrations above 50 µg/ml. Genome sequencing and assembly revealed multiple copies of genes involved with acetate and ammonia metabolism, and several genes involved with secondary metabolite synthesis. An alternative to the high capital investment of photobioreactors for the cultivation of microalgae is the use of open-source and open-hardware bioreactor controller. Here, the concept of an open-hardwate bioreactor control called ``BioBrain'' is introduced. The BioBrain device is based on the Arduino Mega micro-controller board, and is capable of monitoring and controlling culture conditions during simple strain characterization studies, with an estimated construction cost of less than $800 USD. Finally, a new primer design tool for the ligation-independant cloning technique 𝜆-PCR was developed called lambdaPrimeR. The contributions of this work are the discovery and development of different tools that can overcome the challenges of the use of microalgae as microbial cell factories in industrial processes. / Ph. D. / Microalgae are single-celled organisms capable of photosynthesis and have the potential to revolutionize fuel and high-value chemical production. However, the high process costs involving the cultivation and biomass harvesting of these organisms limits the number of industrial applications of microalgae. Therefore, reduction of the overall costs of any process involving microalgae is vital for the widespread use of these organisms in industry. On this dissertation, I explore different approaches to tackle the challenges of using microalgae as a high-value chemicals cell factories. First, the use of anaerobic digestion of salmon offal to generate low-cost nutrients for algae growth is successfully demonstrated, with the discovery of a novel algae isolate Scenedesmus sp. A6, capable of very robust growth on the anaerobic digestion wastewater. Further characterization of this novel isolate showed that it has antimicrobial activity against E. coli cells. Therefore, the Scenedesmus sp. A6 isolate has the potential to be used as a high-value chemical cell factory. Reduction in equipment and instrumentation costs was also achieved by the design and construction of an open-hardware and open-source bioreactor controller device called the “BioBrain”, and a low-cost modular bubble column photobioreactor called “The Big Large Tube”. Together, these two devices represent a significant reduction in equipment costs for the cultivation of microalgae. Finally, an open-source Bioinformatics tool called “lambdaPrimeR” was developed to facilitate the use of a novel Genetic Engineering technique called λ-PCR, that has the potential to make genetic engineering of microalgae much easier.

Due to changes which are occurring in the information technology sector, the way businesses are being carried out and also the development of the Internet. I have set out in this dissertation to identify the perception of customers regarding Internet as a promotional medium. Primarily, I set out to give an overview of marketing issues related to promotion, issues including the customer's perception, buying influences and the decision process, placing a highlight on the marketing mix influences particularly on promotion. I proceeded by giving an outline of the e- commerce and e-business, identifying the different categories within e-commerce, the steps involved in developing e-business within an organisation. The study identified a number of findings related to the perception of customers regarding the Internet as a promotional medium. Some of the most relative findings indicate that customers still perceived the traditional method of advertising as the best type. A positive feedback has been received regarding the Internet as a marketing tool but there seems to be a lack of trust, which has to be dealt with by companies to make customers overcome this obstacle. Finally customers feel that the human interaction is an important element which has to be made present on website.Companies have to do their best to make utmost use of latest technologies and developments, such as the Internet, so as to maximise organisations goals. To do this the whole organisation has to be committed and the implementation has to be a comprehensive one. Furthermore companies have to ensure that such a development should be used not only to communicate to the customers, but with the customers, benefiting from their feedback.