Awareness servers provide information about a person to help observers determine whether a person is available for contact. A trade -off exists in these systems: more sources of information, and higher fidelity in those sources, can improve peoples decisions, but each increase in information reduces privacy. In this thesis, we look at whether the type of relationship between the observer and the person being observed can be used to manage this trade-off. We conducted a survey that asked people what amount of information from different sources that they would disclose to seven different relationship types. We found that in more than half of the cases, people would give different amounts of information to different relationships. We then constructed a prototype system and conducted a Wizard of Oz experiment where we took the system into the real world and observed individuals using it. Our results suggest that awareness servers can be improved by allowing finer-grained control than what is currently available.

It has been suggested that growth, production and community structure of bacterioplankton are dependent on resource availability. However, previous studies have only investigated the effect of either organic substrate mixtures or a few single organic substrates on the bacterioplankton community. The aims of this study were to investigate the impact of five different relevant carbon sources on the bacterioplankton community. This impact was evaluated comparing treatments on samples taken from Skagerrak and the Baltic Sea, in whole seawater cultures. Analysis of bacterial abundance, bacterial production (as leucine incorporation), bacterioplankton DNA community structure and colony-forming bacteria growing on agar plates were evaluated. Differences between carbon sources in terms of bacterial numbers were relatively small, with strong growth responses for L-amino acids, glucose, acetate and pyruvate with the only exception of glycolate where growth was lower. Bacterial production, on the other hand, presented marked differences, different patterns for each carbon source, especially in the Baltic Seawater. Furthermore, differences in colony size and number of colony forming bacteria in the different treatments were important. The analysis of DNA community from each experiment, by denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rDNA, allowed a visualization of the microbial community structure. Sequencing of the stronger bands on the gel revealed the identity of the dominant bacterial species. In terms of bacterioplankton community structure, differences between carbon sources and between environments were important. One unknown species belonging to gamma-proteobacteria was both unique and dominant for glucose treatment in the Baltic experiment. Another gamma-proteobacteria , a Vibrio was found to specialize in glucose in the Skagerrak experiment. One uncultured bacterium belonging to a alpha-proteobacteria, both unique and dominant was found in glycolate, also this in Skagerrak, another uncultured alpha-proteobacteria was clearly dominant for glucose treatment in Skagerrak. Some bands were also present in most treatments, e.g. uncultured species belonging to bacteroidetes in Skagerrak and beta-proteobacteria in Baltic, suggesting that those species are not specialized in consuming a single carbon source. As a conclusion different carbon sources clearly had an individual but important role for bacterioplankton properties. The properties also showed to be dependent on the environment. Nr:6355

This work assesses if a plausible theoretical thermo-chemical scheme can be conceived of, that is capable of extracting work from chemical reactants which can be compared with work produced by a fuel cell, when both processes are supplied with the same reactants. A theoretical process is developed to convert heat liberated from a chemical reaction to work. The hypothetical process is carried over a series of isothermal chemical reactor - heat engine combinations. Conducting the chemical reaction and work extraction over a series of temperature steps minimizes irreversibilities that result from the chemical reaction and heat transfer. Results obtained from the numerical calculations on the scheme confirm that when a large number of reactors-engine combinations are used, irreversibility of the proposed hypothetical reactor-engine combination can be reduced to zero. It is concluded from the results, that the theoretical model is as efficient as a fuel cell when both have the same chemical reaction under identical conditions. The effect of inert gas chemistry on the process has also been observed. It is determined from the results that the chemistry of the inert gas does not affect the proposed process. It is determined from results of a parametric study on the composition of inert gas, that the reduction of inert gas does not significantly improve the efficiency of the proposed process.

The purpose of this study was to determine the feasibility of conducting multiple household food inventories over the course of 30 days to examine weekly food variability. Household food availability influences the foods individuals choose to consume; therefore, by assessing the home food environment a better understanding of what people are eating can be obtained. Methods of measuring home food availability have been developed and tested in recent years; however most of these methods assess food availability on one occasion only. This study aimed to capture "usual" availability by using multiple assessments. After the development and pre-testing of the 171-item home observation guide to determine the presence and amount of food items in the home (refrigerator, freezer, pantry, elsewhere), two trained researchers recruited a convenience sample of 9 households (44.4% minority), administered a baseline questionnaire (personal info, shopping habits, food resources, and food security), and conducted 5 in-home assessments (5-7 day interval) over a 30-day period. Each in-home assessment included shopping and fast food activities since the last assessment and an observational survey of types and amounts of foods present. The final in-home assessment included an audio recorded interview on food habits and beliefs. Complete data were collected from all 9 women (32.8 y +/- 6.0; 3 married; 4 +/- 1.6 adults/children in household; 4 SNAP; 6 food insecure) and their households. Weekly grocery purchases (place, amount, and purpose) use (frequency) varied from once (n=1) to every week (n=5); 4 used fast food 2-3 times/wk for 4 weeks. Quantity and types of fresh and processed fruits and vegetables varied by week and by family. The feasibility of conducting multiple in-home assessments was confirmed with 100% retention from all participants. This methodology is important in that it provided detailed information on intra-monthly variation in food availability. The findings suggest the inadequacy of a single measure to assess food availability in the home.

The IT community has increasingly come to view storage as a resource that should be shared among computer systems and managed independently of the computer systems that it serves. And, the explosive growth of the Web contents has led to increasing attention on two major challenges: scalability and high availability of network file system. Therefore, the ways to improve the reliability and availability of system, to achieve the expected reduction in operational expenses and to reduce the operations of system management of system have become essential issues. A basic technique for improving reliability of a file system is to mask the effects of failures through replication. Consistency control protocols are implemented to ensure the consistency among these replicas. In this dissertation, we leveraged the concept of intermediate file handle to cover the heterogeneity of file system. But, the monolithic server system suffered from the poor system utilization due to the lack of dependence checking between writes and management of out-of-ordered requests. Hence, in this dissertation, we followed the concept of intermediate file handle and proposed an efficient data consistency control scheme, which attempts to eliminate unnecessary waits for independent NFS writes to improve the efficiency of file server group. In addition, we also proposed a simple load-sharing mechanism for NFS client to improve system throughput and the utilization of duplicates. Finally, the results of experiments proved the efficiency of the proposed consistency control mechanism and load-sharing policy. Above all, easy to implement is our main design consideration.

No description available.

This research focused on expanding the capabilities of the Water Rights Analysis Package (WRAP) for incorporating salinity considerations in assessments of water availability. A simulation modeling approach was used to address this issue and a generalized simulation model called WRAP-SALT was developed. The Brazos River Basin served as a case study to test the simulation approach adopted by the model. The simulation model adopts a generalized modeling approach applicable to any river basin system. The model tracks salinity throughout a river basin system over different periods of time for alternative scenarios of water use, reservoir system operating policies, and salt control mechanisms. The model was applied to the Brazos River Basin considering different management scenarios and the results obtained were analyzed. Reservoir reliabilities were assessed under user imposed salinity constraints. It was observed that the water supply reliabilities decreased significantly if salinity constraints were considered. Salt control dams proposed by the U.S. Army Corps of Engineers were also incorporated in the simulation of the river basin. It was observed that salinity in the main stem of the Brazos River was significantly reduced. However, no significant improvement was observed in water supply reliabilities.

The exhaust gas recirculation (EGR) system has been widely used to reduce nitrogen oxide (NOx) emission, improve fuel economy and suppress knock by using the characteristics of charge dilution. However, previous studies have shown that as the EGR rate at a given engine operating condition increases, the combustion instability increases. The combustion instability increases cyclic variations resulting in the deterioration of engine performance and increasing hydrocarbon emissions. Therefore, the optimum EGR rate should be carefully determined in order to obtain the better engine performance and emissions. A thermodynamic cycle simulation of the four-stroke spark-ignition engine was used to determine the effects of EGR on engine performance, emission characteristics and second law parameters, considering combustion instability issues as EGR level increases. A parameter, called 'Fuel Fraction Burned,' was introduced as a function of the EGR percentage and used in the simulation to incorporate the combustion instability effects. A comprehensive parametric investigation was conducted to examine the effects of variations in EGR, load and speed for a 5.7 liter spark-ignition automotive engine. Variations in the thermal efficiencies, brake specific NOx emissions, average combustion temperature, mean exhaust temperature, maximum temperature and relative heat transfer as functions of exhaust gas recycle were determined for both cooled and adiabatic EGR configurations. Also effects of variations in the load and speed on thermal efficiencies, relative heat transfers and destruction of availability due to combustion were determined for 0% EGR and 20% EGR cases with both cooled and adiabatic configurations. For both EGR configurations, thermal efficiencies first increase, reach a maximum at about 16% EGR and then decrease as the EGR level increases. Thermal efficiencies are slightly higher for cooled EGR configuration than that for adiabatic configuration. Concentration of nitric oxide emissions decreases from about 2950 ppm to 200 ppm as EGR level increases from 0% to 20% for cooled EGR configuration. The cooled EGR configuration results in lower nitric oxide emissions relative to the adiabatic EGR configuration. Also second law parameters show the expected trends as functions of EGR. Brake thermal efficiency is higher for the 20% EGR case than that for the no EGR case over the range of load (0 to WOT) and speed (600 rpm to 6000 rpm). Predictions made from the simulation were compared with some of the available experimental results. Predicted thermal efficiencies showed a similar trend when compared to the available experimental data. Also, percentage of unused fuel availability increases as the EGR level increases, and it can be seen as one of the effects of deteriorating combustion quality as the EGR level increases.

A new method is developed to schedule jobs on parallel machines with availability constraints. The objective of the problem is to minimize the makespan of the total production schedule. Without the availability constraints the scheduling of machines is a Pm || Cmax problem. The scheduling of this problem was the topic of many earlier papers. The main contribution of this research is that the schedule of the jobs on parallel machines with availability constraints is determined within a single implicit enumer- ation algorithm. Within the general enumeration scheme, the loads of each machine are enumerated in a lexicographic order. An exact integer linear programming model is provided, too. The difficulty of the problem depends on the properties of the pro- cessing times, the number of machines, and the number of availability constraints on the machines. In some subclasses, problems with very large number of jobs are solved. The largest problems solved within one hour limit have 1, 000, 000 jobs.

No description available.