The focus of this thesis is on the vertical integration of mechatronics in the mechanical engineering curriculum at Virginia Tech. It reports the details of an experimental strategy to integrate mechatronics at an early level in the education of engineers. A proposal was submitted to and accepted by the NSF/SUCCEED coalition to fund this experiment. Through this assistance, the experiment of vertically integrating mechatronics was initiated. The methodology in which it was integrated is presented -- through optional participation in a sophomore design class and a required design project in a junior system dynamics course. The material developed for the vertical integration of mechatronics is in the appendices. This material is appropriate for other institutions to use to vertically integrate mechatronics into their curriculums, which is part of the NSF/SUCCEED coalition's initiative. For the sophomore class, ME 2024, Introduction to Engineering Design and Economics, selected sections were exposed to the concepts of mechatronic design, along with the normal course material. Students in the mechatronic sections were given an opportunity to incorporate the use of a custom-built VT Project Box and the PIC Visual Development (PVD) software, both of which were created specifically for the task of vertical integration of mechatronics. Throughout the semester, the students were given several demonstrations of mechatronic systems through the use of the project box and software. Many students decided to implement mechatronic concepts in their final design projects. A smaller number of students made a decision to use the project box and software to develop a prototype of their final design project. Candid remarks about the students experiences, obtained from a survey at the semester's end, indicated that the vertical integration of mechatronics was a motivational feature in the second-year curriculum. For the junior class, ME 3514, System Dynamics, all sections were exposed to the concepts of mechatronics, along with the normal course material. The students were required to acquire steady-state velocity data from a DC motor and create an analytical model of the motor to predict the steady-state velocity for a given duty cycle of a pulse-width modulated controller. After the collection of the data and the creation of the analytical model, the students compared the results of simulations to the actual data collected, and report the comparison to the instructor in a memorandum. The collection of the steady-state velocity data was accomplished using the PVD software and the VT Project Box. The essentials of mechatronics was communicated to the students in two lectures, and the students gained hands-on experience with mechatronics through the use of the project box and the software. The lecture material covered the basics of mechatronics, the Mechatronics course at Virginia Tech, and detailed information about the design project. The assessment of the vertical integration of mechatronics into this junior course was accomplished by surveying all of the students in the course. The results of the survey indicated that the inclusion of mechatronics material increased the students understanding of the course material and also increased their interest in mechatronics. / Master of Science

No description available.

Several aesthetic, health, and plumbing quality issues can arise during new construction or renovation of premise plumbing. There has been little research done on many of these concerns and therefore few guidelines or regulations are in place to protect the health of the consumer or the integrity of the plumbing infrastructure. This work examines common construction practices including: 1) effect of residual construction debris, 2) shock chlorination of new plumbing lines, and 3) lead leaching propensity of new brass ball valves. During installation of plumbing systems, residual chemicals and debris including copper brass particles and flux, can be left in plumbing lines following construction and installation. This debris is considered undesirable from health, aesthetic, and corrosion perspectives. Soldering flux is of particular concern due to its corrosive nature. Experiments were conducted to determine the effects of residual solder flux, PVC glue, and metallic debris and to quantify flushing velocities and durations to effectively remove them from a new plumbing system. A flushing velocity of 3 fps for 30 minutes is needed to remove water soluble flux, while petroleum based flux still persists after extensive flushing at 7 fps. Currently a practice known as shock chlorination, whereby super chlorinated water is used for disinfection, is used in water mains after installation or repair as specified in the ANSI/AWWA C651 Standard. This practice is now starting to be required by some building codes in premise plumbing for new construction. Water mains are typically made of concrete where as premise plumbing using copper or PVC piping. Copper pipe is susceptible to attack by high chlorine, and this reaction will also remove the chlorine residual. There is concern about potential damage to copper from free chlorine and that in some systems targeted residuals of chlorine might not be obtained. Experiments did not detect serious damage to copper pipe, but in some waters it was not possible to meet targeted residual levels of chlorine. The addition of orthophosphate corrosion inhibitor or adjustment of pH can sometimes reduce the chlorine decay rate. Extremely high and persistent lead leaching in a brand new building at the University of North Carolina (UNC) traced to leaded bronze ball valves, prompted an extensive forensic evaluation how existing standards (National Sanitation Foundation Section 8) could allow for installation of products that could create a human health hazard due to high lead. Diffusion of lead from within the device to water in the pipe, high velocity, microbial activity and other factors caused more leaching in practice than would be expected based on NSF testing and normalization factors applied to certify a valve as safe. Moreover, use of flux during soldering of joints, increased lead leaching by orders of magnitude relative to results of NSF testing without flux. / Master of Science

The ban on lead plumbing materials in the Safe Drinking Water Act (1986) and the EPA Lead and Copper Rule (1991) have successfully reduced lead contamination of potable water supplies. The success of these regulations gave rise to a belief that serious lead contamination was an important past problem that had been solved, and that additional fundamental research was therefore unnecessary. This work carefully re-examined the lead contamination issue from the perspective of 1) new regulations causing a shift from chlorine to chloramine disinfectant, 2) assumptions guiding sampling strategies, 3) existing performance standards for brass, and 4) galvanically driven corrosion of lead bearing plumbing materials. The results were instrumental in uncovering and understanding a serious problem with lead contamination in Washington, D.C. A critical reading of the literature indicates that chloramines can accelerate corrosion of lead bearing materials and increase lead contamination of water. When a new sampling protocol was conceived and used in Washington homes to assess the nature of the problem, hazardous levels of lead were found to be present in some drinking water samples. Contrary to the conventional wisdom, lead was not always highest in first draw samples, but often increased with flushing. This has several important implications for monitoring and public health. For instance, well-intentioned public education materials were causing consumers to drink water containing very high levels of lead in some circumstances. Laboratory and field-testing proved that chloramines were causing serious lead corrosion problems. That testing also discovered that, unbeknownst to scientists and utilities, free chlorine itself can act as a corrosion inhibitor, reducing lead solubility and contamination of water. The net result is that changing disinfectant from free chlorine to chloramine can sometimes trigger serious lead contamination of water. While the worst problems with lead in Washington, D.C. came from the lead services, significant levels of lead were occasionally sampled from homes with solders or brass as the lead source. This prompted re-evaluation of the ANSI/NSF 61, Section 8 standard, which is relied on to protect public health from in-line brass plumbing devices that might leach excessive lead to potable water. In-depth study of the standard revealed serious flaws arising from use of a phosphate buffer in the test waters and a failure to control carbonate dissolution from the atmosphere. Due to these deficiencies, small devices made of pure lead could actually pass the performance test. The public therefore has no assurance that devices passing NSF Section 8 testing are safe and reforms to the standard are obviously needed. Other problems arise from connecting copper pipe to lead bearing plumbing in practice. The copper is cathodic and dramatically accelerates corrosion of the lead anode via a galvanic current. Corrosion and hydrolysis of released Pb²⁺ can lower pH near the surface of the lead and increase its solubility. A similar galvanic effect can arise from cupric ions present in the water via deposition corrosion mechanism. In cases where part of a lead service line is replaced by copper pipe, the galvanic corrosion effect can create a serious long-term problem with lead contamination. Such partial lead service line replacements are occurring in many US cities and the practice should be stopped. Lead contamination of potable water is not only a problem of the past but also of the present. While additional research is necessary before regulators, utilities and homeowners can anticipate and mitigate such problems with confidence, this work provides sound fundamental basis for future progress. / Master of Science

No description available.

No description available.

Thèse diffusée initialement dans le cadre d'un projet pilote des Presses de l'Université de Montréal/Centre d'édition numérique UdeM (1997-2008) avec l'autorisation de l'auteur.

Thèse diffusée initialement dans le cadre d'un projet pilote des Presses de l'Université de Montréal/Centre d'édition numérique UdeM (1997-2008) avec l'autorisation de l'auteur.

Master of Science

Growing concern over adverse health effects from low level lead exposure motivated reassessment of lead occurrence in drinking water, from the perspective of 1) possibly eliminating lead from new brass materials, and 2) performance testing of existing products. During the course of this thesis work, it was discovered that several cases of childhood lead poisoning in North Carolina, South Carolina and Washington D.C. occurred from contaminated potable water. That disconcerting finding prompted additional work into 3) deficiencies in existing lead testing of drinking water samples, and 4) impacts of water treatment steps on lead leaching. Meters, components, and fittings manufactured from non-leaded brass (< 0.25 percent lead content) are increasingly specified for use in water distribution systems and premise plumbing, in response to California's Proposition 65 and the proposed Lead Free Drinking Water Act. An in-depth review of the available literature revealed that non-leaded brass releases minimal amounts of lead and other contaminants of concern to drinking water. There is legitimate concern about the corrosion resistance and longevity of these non-leaded alloys in the range of waters that will be encountered in practice. Nonetheless, when the potential impacts to manufacturers, utilities and consumers are considered, non-leaded brasses appear to be attractive albeit at slightly higher cost. For existing leaded brass products, concerns have been raised over potential limitations of performance standards used to certify the products as "safe" in the marketplace. The ANSI/NSF 61 Section 9 test is the industry standard, and its protocol is critically evaluated from the perspective of the leaching solution chemistry. Testing indicated that the protocol water is reasonably representative of a typical water supply. However, some lower pH and lower alkalinity waters can be much more aggressive than the existing section 9 water, and for potable water with these characteristics, problems with higher than desired lead leaching may occur. It may be desirable to tighten the standard's pass/fail lead criterion in order to account for this problem in practice. Several cases of childhood lead poisoning from water have been recently encountered, which prompted environmental assessments. It was visually obvious that some of the lead particles ingested by these children, present in water from the tap, were not completely dissolving in the standard method with weak acid recommended by the US EPA. A laboratory investigation proved that up to 80% particulate lead in water samples could be "missed" by the standard protocol. Unfortunately, tests with simulated gastric fluid revealed that much of this particulate lead would be bioavailable in the presence of chloride, warmer temperatures and lower pH inside the human stomach. It is recommended that water utilities be alert to this possible problem and that environmental assessments of lead poisoned children use stronger digestions to detect lead in water. Several of the lead poisoning instances occurred after the utility changed both disinfectant chemicals (from chlorine to chloramine) and coagulant types. Although authorities initially thought chloramine was the cause based on experiences in Washington D.C., bench scale studies in this work proved that a change in coagulant from aluminum sulfate to either ferric chloride or polyaluminum chloride was in fact the main reason of the lead spikes. The reduction in sulfate and increase in chloride increased the chloride to sulfate mass ratio of the water supply. A higher chloride to sulfate mass ratio triggered much higher (2.3-40 times more) lead leaching from solder connected to copper pipe. The adverse effects of the increase in the ratio could not be eliminated by adding a corrosion inhibitor. / Master of Science