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To learn about computer operating systems, students at Virginia Tech implement a command-line shell in their Computer Systems course. Successfully implementing the shell requires a deep understanding of operating system abstractions and interactions. Students often struggle with the project because subtle errors can take hours to debug. In this work, we developed two hybrid domain-specific analysis tools to pinpoint the root causes of student errors: EshMD and ShellTrace. The EshMD tool models common errors in the shell and checks the student code against those models. To accomplish this, it monitors the specific calls the program is making and correlates those with expected changes in its environment. Students' errors are shown directly in the source code. The concept of EshMD can be applied to other programming projects by observing and modeling common bugs during implementation. The ShellTrace tool dynamically creates a specification from a reference solution based on how the reference solution makes use of operating system resources and then uses this specification to check that a student solution is functionally identical. The ShellTrace concept can be applied to other programs that exhibit similar resource dependencies. We deployed these tools in an undergraduate computer systems class and evaluated our tools based on the number of bugs detected and the students' perceptions of usefulness. We found that the tools detected a significant number of bugs and that the majority of students that made use of the tools found them valuable in debugging their submissions. / Master of Science / To learn about computer operating systems, students at Virginia Tech implement a command-line shell in their junior-level Computer Systems course. A command-line shell is a computer program that allows the user of a computer to run other programs by typing in the program names. The command-line shell will then run those programs on the user’s behalf. The command-line shell project requires students to understand and use the abstractions that the underlying operating system provides to a computer program. Students often struggle with the project because subtle errors in their implementation can take hours to address. In this work, we developed two analysis tools to pinpoint the root cause of student errors: EshMD and ShellTrace. The EshMD tool models common errors in the command-line shell and checks the student code against those models. Students’ errors are shown by directly pointing to the error locations in their code. The ShellTrace tool dynamically creates a project specification from a solution written by the course staff and checks that a student solution meets the specification. Generating from the staff solution allows checking the student solution without having to encode the specific project requirements into the tool itself. We deployed these tools in an undergraduate computer systems class and evaluated our tools based on the number of errors detected and the students’ perceptions of usefulness. We found that the tools detected a significant number of errors and that the majority of students that made use of the tools found them valuable in finding and fixing the errors in their submissions.

This thesis deals with administrative and economic tools as a part of instrumentarium of environmental protection. I have chosen this topic for the following reasons. Protection of the environment is an important and actual issue of nowadays, it represents one of the three essential pillars of sustainable development, along with economic and social pillar. In order to achieve an effective environmental protection, it is necessary to embed the most important tools of environmental policy in law. Only then it is possible to successfully enforce relevant measures. Administrative and economic tools represent the most important sets of instruments of environmental protection for they have a great potential to resolve environmental problems. This potential is, however, not utilized enough in a number of cases. Both administrative and economic tools of environmental protection are regularized - they have a chance to directly (administrative tools) or indirectly (economic tools) affect the behaviour of a large number of subjects in an ecological friendly way. The thesis is composed of three main parts - 1.Tools of environmental protection, 2.Administrative tools of environmental protection, 3.Economic tools of environmental protection - each of them subdivided into chapters and subchapters. Part One is...

The topic of this master thesis is the historical investigation of kitchen tools that evolved towards a multifunctional nature. The history of kitchen tools will be discussed with particular attention given to industrialization, technological developments and the effects of mechanization. Following this analysis, there will be a classification that could serve as a resource material for future studies, made according to the activity flow within the kitchen, in order to understand the interrelations within and between these products. This classification will be put forward in the form of a visual table that includes morphological analyses of specifically mixing and beating tools under the topic of food preparation, how they developed historically following the industrial revolution, and how they carry a tendency to become increasingly multifunctional. According to this table, the dispositions and interrelations of these products will be considered, concluding with a situational analysis and previsions for future designs and studies.

This study investigates the use of vibration and strain measurements on machine tools in order to identify the propagating wear of the selected tools. Two case studies are considered, one of which was conducted in the plant of a South African piston manufacturer. The purpose of the ftrst case study was to investigate the feasibility of vibration monitoring to identify tool wear, before attempting to implement a monitoring system in the manufacturing plant. During this case study, data from a turning process was recorded using two accelerometers coupled to a PL202 real time FFT analyser. Features indicative of tool wear were extracted from the sensor signals, and then used as inputs to a Self-Organising Map (SOM). The SOM is a type of neural network based on unsupervised learning, and can be used to classify the input data into regions corresponding to new and worn tools. It was also shown that the SOM can also be used very efficiently with discrete variables. One of the main contributions of the second case study was the fact that a unique type of tool was investigated, namely a synthetic diamond tool specifically used for the manufacturing of aluminium pistons. Data from the manufacturing of pistons was recorded with two piezoelectric strain sensors and a single accelerometer, all coupled to a DSPT Siglab analyser. A large number of features indicative of tool wear were automatically extracted from different parts of the original signals. These included features from time and frequency domain data, time series model coefficients as features and features extracted from wavelet packet analysis. A correlation coefficient approach was used to auto-lJUltically select the best features indicative of the progressive wear of the diamond tools. The SOM was once again used to identify the tool state. Some of the advantages of using different map sizes on the SOM were also demonstrated. A near 100% correct classification of the tool wear data was obtained by training the SOM with two independent data sets, and testing it with a third independent data set. It was also shown that the monitoring strategy proposed in the second case study can be fully automated and can be implemented on-line if the manufacturer wishes to. Some of the contributions of this study are the use of the SOM for tool wear classification, and conclusions regarding the wear modes of the synthetic diamond tools. / Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2006. / Mechanical and Aeronautical Engineering / unrestricted

Workers within production and assembly lines are often exposed to ergonomically unfavorable tasksand conditions. Reaction forces and reaction torques generated by industrial power tools may causenot only discomfort but also health issues and injury. The forceful tasks in combination with highlyrepetitive hand-arm motions and prolonged tool use paves the way for loss in workforce capacitywhich in turn can lead to great losses in productivity and product quality. An umbrella term for themany injuries and diseases that may arise from the use of such tools is Cumulative Trauma Disorders(CTD).This study aimed to investigate the ergonomic effect of power tool use for various tool and taskrelated conditions. The study required the setup of a test rig with a simulated handle of the tool. Theergonomic impact was assessed by measuring the torques associated with different tighteningstrategies, as well as measuring the angular displacement of the tool handle. By varying the jointstiffness and workplace orientation, the complexity of the task was varied and thus quantified.Measurements of muscle activity during each tightening procedure provided a quantification of thephysiological impact on the operator. By combining the measurements on the operator withsubjective assessment of perceived exertion and discomfort, a more holistic perspective on thetightening procedure was obtained.The results obtained from the study stressed the negative impact on the operator which the QuickStep tightening strategy on medium hard joints implies, regardless of workspace orientation. TheTurbo Tight and Tensor Pulse tightening strategies turned out to generate the lowest reactiontorques and handle deflections, regardless of joint stiffness and workspace orientation. The findingsfrom the muscle activity measurements in combination with the subjective evaluation methodsfurther confirmed the mildness of the Turbo Tight and Tensor Pulse strategies. Moreover, horizontalworkspace resulted in lower tool handle deflection compared to vertical workspace for all tighteningstrategies and joint stiffnesses. / Många antällda på monteringsband exponeras ofta för ergonomiskt ofördelaktiga arbetsuppgifter och arbetsförhållanden. De handhållna monteringsverktyg som används genrerar ofta reaktionskrafter som i många fall kan orsaka en känsla av obehag eller ge upphov till mer bestående hälsobesvär. De kraftfulla och repetetiva arbetsuppgifterna som montering många gånger innebär kan bana väg för förluster i arbetskraftskapacitet, vilket i sin tur kan leda till stora förluster i produktivitet och produktkvalitet. En paraplyterm för de många åkommor och besvär som kan uppstå som ett resultat av användandet av handhållna monteringsverktyg är ’förslitningsskador’ (Cumulative Trauma Disorders på engelska). Målsättningen för denhär studien har varit att undersöka de ergonomiska effekter som användandet av handhållna monteringsverktyg innebär vid olika vektygs- och arbetsuppgiftsrelaterade parametrar. Studien genomfördes med hjälp av en test rig där ett simulerat verktygshandtag utnyttjades. Den ergonomiska effekten på användaren undersöktes genom mätningar av uppnådda reaktions moment och handtags vinklar associerade med olika åtdragningsstrategier, styvhet av förband samt orientering av arbetsyta. Genom att mäta muskelaktiviteten i underarmen hos testpersonerna erhölls en kvantifiering av den fysiologiska effekten på testpersonerna. Mätningarna av vinkel, moment och muskelaktivitet kombinerades med subjektiva skattningsmetoder för att på så sätt kunna erhålla ett mer holistiskt perspektiv på åtdragningarna och deras effekt på människan. Resultaten från studien underströk de negativa effekterna av åtdragning med Quick Step strategin på medium hårda förband, oavsett orientering av arbetsytan. Turbo Tight och Tensor Pulse strategierna genererade de lägsta reaktions momenten och handtags deflektionerna. Resultaten från muskelsaktivitetsmätningarna och de subjektiva skattningsmetoderna bekräftade den relativa mildheten hos Tensor Pulse och Turbo Tight strategierna. Dessutom påvisades att åtdragningar som sker på en horisontell arbetsyta resulterade i lägre handtagsdeflektion jämfört med åtdragningar på en vertikal arbetsyta, oavsett åtdragningsstrategi och styvhet hos förband.

The examination of the tools that prehistoric people crafted for subsistence and related practices offers distinctive insights into how they lived their lives. Most often, researchers study these practices in isolation, by tool type or by material. However, by using a relational perspective, my research explores the tool assemblage as a whole including bone, stone and shell. This allows me to study the changes in tool industries in relation to one another, something that I could not accomplish by studying only one material or tool type. I use this broader approach to tool manufacture and use for the artifact assemblage from Crystal River (8CI1) and Roberts Island (8CI41), two sequential Middle and Late Woodland Period (A.D. 1-1050) archaeological sites on the central Gulf coast of Florida. The results of my research show that people made different choices, both in the type of material they used and the kind of tools they manufactured during the time they lived at these sites as subsistence practices shifted. Evidence of these trends aligns with discrete changes in strata within our excavations. The timing of depositional events and the artifacts found within each suggest people also used the sites differently through time. These trends exemplify the role of crafting tools in the way people maintain connections with their mutable social and physical world.

This report aims to draw a comparison between two commercial mobile forensics and recovery tools, Magnet AXIOM and MOBILedit. A thorough look at previously done studies was helpful to know what aspects of the data extractions must be compared and which areas are the most important ones to focus upon. This work focuses on how the data extracted from one tool compares with another and provides comprehensive extraction based on different scenarios, circumstances, and aspects. Performances of both tools are compared based on various benchmarks and criteria. This study has helped establish that MOBILedit has been able to outperform Magnet AXIOM on more data extraction and recovery aspects. It is a comparatively better tool to get your hands on.

Call number: LD2668 .T4 1963 M49 / Master of Science

Call number: LD2668 .T4 1964 K43 / Master of Science