No description available.

<p>A MATLAB code for calculating neutron energy spectra from JET discharges was developed. The code uses the fuel ion distribution calculated by the computer code SELFO to generate the spectrum through a Monte-Carlo simulation. The calculated spectra were then compared against experimental results from the neutron spectrometer TOFOR. In the calculations, the exact orbits of the fuel ions are taken into account, in order to investigate what effects this has on the spectrum. The reason for this is that, for certain plasma heating scenarios, large populations of fast fuel ions are formed. These fast ions may have Larmor radii of the order of decimeters, which is comparable to the width of the sight line of TOFOR, and may therefore affect the recorded neutron spectrum. A JET discharge with both NBI and 3rd harmonic ICRF heating was analyzed. The results show that the details of the line of sight of the detector indeed affects the neutron spectrum. This effect is probably important for other diagnostics techniques, such as gamma-ray spectroscopy and neutral particle analysis, as well. Good agreement with TOFOR data is observed, but not for the exact same time slice of the discharge, which leaves some questions yet to be investigated.</p>

The purpose of this research is to develop an approach to minimize makespan for assigning boards to production lines. Because of sequence-dependent setup issue, board assignment and component allocation have to be performed concurrently. An integrated methodology is proposed to obtain a solution of the two problems. The methodology consists of seven phases: PCB grouping, family decomposition, subfamily sequencing, Keep Tool Needed Soonest (KTNS), component setup determination, component allocation, and board assignment. PCB grouping based on component similarity between boards is used to reduce the problem size. Family decomposition is used when total number of feeder slots required by a family exceeds feeder capacity. Subfamily sequencing and Keep Tool Needed Soonest are applied to minimize the number of component setups. Classification of setup components into standard, semi-standard, and custom setup components is performed to reduce the complexity of the component allocation problem. A component allocation algorithm is developed to balance workload across machines. Assigning board families to production lines is performed using a modification of Longest Processing Time (LPT) rule. Assigning entire PCB families to production lines to minimize makespan is difficult to accomplish since the amount of production time for each family is very large compared to that of individual PCB lot. Splitting some subfamilies is allowed as long as this does not increase makespan. The PCB grouping, family decomposition, subfamily sequencing, Keep Tool Needed Soonest (KTNS), and component setup determination procedures are derived from published research results. The component allocation and board assignment are developed in this research, as well as an overall methodology to integrate the entire problem. Data provided by published literature are employed to evaluate performance of the component allocation algorithm and the integrated methodology. To examine the applicability of the methodology, an industrial data is used with the total imbalance due to setup time and placement time of individual PCB and global makespan as the performance measures. Experimentation is conducted with simulated data based on an industry data to investigate impact of threshold value, feeder capacity, and characteristics of data sets on system performance. / Graduation date: 2002

This thesis describes the application of Bayesian networks for monitoring and diagnosis of a multi-stage manufacturing process, specifically a high speed production part at Hewlett Packard. Bayesian network "part models" were designed to represent individual parts in-process. These were combined to form a "process model", which is a Bayesian network model of the entire manufacturing process. An efficient procedure is designed for managing the "process network". Simulated data is used to test the validity of diagnosis made from this method. In addition, a critical analysis of this method is given, including computation speed concerns, accuracy of results, and ease of implementation. Finally, a discussion on future research in the area is given. / Graduation date: 1999

Jobs arriving over time must be non-preemptively processed on one of m parallel machines, each of which running at its own speed, so as to minimize a weighted sum of the job completion times. In this on-line environment, the processing requirement and weight of a job are not known before the job arrives. The Weighted Shortest Processing Requirement (WSPR) on-line heuristic is a simple extension of the well known WSPT heuristic, which is optimal for the single machine problem without release dates. We prove that the WSPR heuristic is asymptotically optimal for all instances with bounded job processing requirements and weights. This implies that the WSPR algorithm generates a solution whose relative error approaches zero as the number of jobs increases. Our proof does not require any probabilistic assumption on the job parameters and relies extensively on properties of optimal solutions to a single machine relaxation of the problem. / Singapore-MIT Alliance (SMA)

Home networking is becoming an attractive application not only for the Internet access but also for home automation. Being a high-speed and dominant standard presently, HomePlug has an important role in home LAN connecting to the Internet. For industrial applications, the Power Line Communication also has significant advances. However, the PHY/MAC technology provided by HomePlug still cannot be employed with some critical features such as real time performance, implications in the event of link and node loss. In this paper, the characteristics of HomePlug PHY/MAC, the property of power line channel, as well as the noise features of power line are analyzed. Based on HomePlug, a model of high level real-time protocol applied to industrial environment is proposed. The protocol simultaneously belongs to layer two and three, and can support real-time implementation with no loss and small delay according to the requirement in PLC networks, for targeting to develop a real time network with high speed power line media and advanced modulation. / Singapore-MIT Alliance (SMA)

We consider the scheduling problem of minimizing the average weighted completion time on identical parallel machines when jobs are arriving over time. For both the preemptive and the nonpreemptive setting, we show that straightforward extensions of Smith's ratio rule yield smaller competitive ratios compared to the previously best-known deterministic on-line algorithms, which are (4+epsilon)-competitive in either case. Our preemptive algorithm is 2-competitive, which actually meets the competitive ratio of the currently best randomized on-line algorithm for this scenario. Our nonpreemptive algorithm has a competitive ratio of 3.28. Both results are characterized by a surprisingly simple analysis; moreover, the preemptive algorithm also works in the less clairvoyant environment in which only the ratio of weight to processing time of a job becomes known at its release date, but neither its actual weight nor its processing time. In the corresponding nonpreemptive situation, every on-line algorithm has an unbounded competitive ratio

S.B. Gershwin, I.C. Schick. / "October, 1978." Caption title. / Bibliography: leaf 6. / Supported by the National Science Foundation under Grant no. NSF/RANN APR76-12036

This research is an experimental, field and numerical study of the sedimentation and consolidation of in-line thickened oil sands fine tailings. In-line thickening is a process that adds flocculant and coagulant into a modified tailings pipeline in a multi stage fashion to improve the dewatering behaviour of oil sands fine tailings cyclone overflow. The parent untreated cyclone overflow, in-line thickened tailings and sheared in-line thickened tailings were investigated in the laboratory. In-line thickened tailings were produced in the laboratory using the same process as in the field project and sheared in-line thickened tailings were prepared by shearing the thickened tailings with a specified shearing effort to simulate tailings transportation. A combination of hindered sedimentation tests, compressibility standpipe tests and large strain consolidation tests with vane shear tests was then used to capture a full range of sedimentation, consolidation and shear strength characteristics for these materials. Results show that the in-line thickening process significantly improves hydraulic conductivity and undrained shear strength of the fine tails. Shearing damages some of the floc structure but does not cause the material to fully return to the original state of the cyclone overflow. The laboratory data of the in-line thickened tailings was compared with field performance at two in-line thickened tailings pilot scale ponds and with a validation standpipe test by utilizing a developed finite strain consolidation model. Good agreements were obtained between the field performance, the laboratory test results and the validation standpipe test. These good agreements confirmed the validity of the laboratory determined geotechnical parameters and of the developed numerical model and indicated that it is possible to model large scale field performance with small scale laboratory tests. Finally, composite tailings was made from the in-line thickened tailings and was found to have a similar segregation boundary to that of gypsum treated composite tailings made with mature fine tailings but had a much higher hydraulic conductivity and shear strength which were inherited from the flocculated fines. / Geotechnical Engineering

Prenatal alcohol exposure is known to have many profound detrimental effects on human fetal development (fetal alcohol spectrum disorders), which may manifest into lifelong disabilities. Although hearing deficiency is a recognized effect, how alcohol affects the auditory/vestibular systems has not been well studied. This is the first study that used the zebrafish, Danio rerio, as a model organism to investigate morphological effects of alcohol on the developing octavolateral system (auditory, vestibular and lateral line). Zebrafish embryos of two hours post fertilization (hpf) were treated in 2% alcohol for 48 hours and screened at 72 hpf for morphological defects of the inner ear and lateral line neuromasts. Inner ear size and otoliths of zebrafish from both alcohol-treated and control groups were examined using light microscopy. Zebrafish were stained with fluorescent vital dyes to visualize lateral line hair cells using confocal microscopy. The size of neuromasts and length of kinocilia were measured using scanning electron microscopy. Results reveal that alcohol treatment during the early development impairs the formation of otoliths, neuromasts and their hair cells, as well as ear size and kinocilium length. We observed several otolith phenotypes including zero, one, two abnormal, two normal and multiple otoliths for alcohol-treated zebrafish. Fetal alcohol exposure appears to severely impact the size of both anterior and posterior lateral line neuromasts. Our results indicate that early fetal alcohol exposure most likely results in functional defects of the octavolateral system due to inner ear and lateral line dysmorphology.