This thesis investigates some aspects of the inverse Compton scattering process within various physical contexts in high energy astrophysics. Initially an introduction to the key results of Comptonization theory for the case of scattering in optically thick plasmas is given, using a diffusion approach, since these results are required for the interpreta- tion of Comptonized spectra. Since Comptonization in astrophysical systems is frequently treated using numerical techniques, an introduction to these is then presented. Such linear Monte Carlo photon transport codes are typically applied to scattering in plasmas without temperature and density gradients. Additionally, treating bulk motion can be difficult even for simple cases. It is demonstrated that these problems can be made tractable numerically with the use of algorithms associated with non-linear Monte Carlo codes. Such codes can already treat scattering within arbitrary velocity structures in a plasma, and an extension of the algo- rithm is proposed that enables the easy calculation of photon transport in plasmas with non-constant density as well as non-constant temperature and/or bulk motion. This algorithm and code has been developed to treat scattering in astrophysical situations where bulk motion, temperature gradients and density gradients are simultaneously present in a plasma. Both a semi-analytic approach and the numerical approach are then used to treat Comp- tonization problems of current interest. Firstly, the standard two-phase disk-corona model for the high-energy spectra of Active Galactic Nuclei is modified to include an an outflow or wind which may provide an additional source of disk cooling. Earlier slab disk-corona models predict a spectral index which is consistent with observations only if all the accretion power is dissipated in the corona. For the models investigated here, energy spectral indices that are consistent with observations can be obtained with less accretion power being dissipated in the corona, as a result of an outflow/wind. However, it is required that the wind extract large amounts of power from the disk, and it it yet to be seen if this is a plausible scenario.

The research presented in this thesis involves the study of ice cloud microphysical and optical properties using both hyperspectral and narrowband infrared spectral data. First, ice cloud models are developed for the Infrared Atmospheric Sounding Interferometer (IASI) instrument onboard the METOP-A satellite, which provide the bulk-scattering properties of these clouds for the 8461 IASI channels between 645 and 2760 cm-1. We investigate the sensitivity of simulated brightness temperatures in this spectral region to the bulk-scattering properties of ice clouds containing individual ice crystal habits as well as for one habit distribution. The second part of this thesis describes an algorithm developed to analyze the sensitivity of simulated brightness temperatures at 8.5 and 11.0 µm to changes in effective cloud temperature by adjusting cloud top height and geometric thickness in a standard tropical atmosphere. Applicability of using these channels in a bi-spectral approach to retrieve cirrus cloud effective particle size and optical thickness is assessed. Finally, the algorithm is applied to the retrieval of these ice cloud properties for a case of single-layered cirrus cloud over a tropical ocean surface using measurements from the Moderate Resolution Infrared Spectroradiometer (MODIS). Cloud top height and geometric thickness in the profile are adjusted to assess the influence of effective cloud temperature on the retrieval.

Bulk electric system reliability assessment is an important activity in both vertically integrated and unbundled electric power utilities. The conventional deterministic N-1 criterion normally used in bulk electric system planning does not respond to the probabilistic factors that influence the reliability of the system and is a rigid criterion. New assessment procedures are therefore required that combine the traditional deterministic approach with probabilistic perspectives to provide a responsive planning criterion.<p>This research work introduces the concept of a joint deterministic-probabilistic (D-P) criterion for bulk electric system planning using a previously developed software package designated as MECORE. The D-P concept presented is a deterministic framework that incorporates a probabilistic criterion. This research examines the application of the conventional deterministic N-1, the basic probabilistic and the D-P criteria to two test systems. The studies show that the D-P approach is driven by the accepted deterministic N-1 criterion and influenced by the probabilistic criterion (Pc). The D-P technique adds additional probabilistic risk information to the traditional deterministic N-1 criterion that is useful when making system reinforcement decisions. <p>The research work illustrated in this thesis indicates that the D-P criterion and associated procedures for bulk electric system analysis can be effectively utilized in bulk electric system reliability assessment. The conclusions and the techniques presented in this thesis should prove valuable to those responsible for composite generation and transmission system expansion planning.

Abstract Corporate cultures have since the 80's, when the phenomenon was associated with a company's economic success, been a frequent research object. Corporate culture is then often described as something that can create efficiency, success and loyal employees. Often discussed about strong corporate cultures are that members in the organization have accepted the same norms, values and goals. Research also mention unique corporate cultures, where no organization is alike, depending their different stories, leaders, backgrounds or geographical locations.

   This study aims, through observations and interviews on an ethnographic basis, to describe the corporate culture in Stena Bulk. Stena Bulk, a shipping company that was started in the early 80's and is a part of Stena Group, has offices in Gothenburg, Houston, Copenhagen, Singapore and Rio de Janeiro, and has since it’s start greatly expanded in the changing shipping industry.
   The conclusions drawn are that Stena Bulk's culture can be described as strong since the loyal members in the organization often accept the fundamental norms and values. Also identified is that in the company’s different offices varying sizes of groups exist for different reasons With it’s new leadership, Stena Bulk’s culture is an organization in transition and impact for the future on the culture is yet to be seen. Company’s symbolism and image studied in the organization also shows that the corporate culture is not always what the employees describe it to be.

Bulk electric system reliability assessment is an important activity in both vertically integrated and unbundled electric power utilities. The conventional deterministic N-1 criterion normally used in bulk electric system planning does not respond to the probabilistic factors that influence the reliability of the system and is a rigid criterion. New assessment procedures are therefore required that combine the traditional deterministic approach with probabilistic perspectives to provide a responsive planning criterion.<p>This research work introduces the concept of a joint deterministic-probabilistic (D-P) criterion for bulk electric system planning using a previously developed software package designated as MECORE. The D-P concept presented is a deterministic framework that incorporates a probabilistic criterion. This research examines the application of the conventional deterministic N-1, the basic probabilistic and the D-P criteria to two test systems. The studies show that the D-P approach is driven by the accepted deterministic N-1 criterion and influenced by the probabilistic criterion (Pc). The D-P technique adds additional probabilistic risk information to the traditional deterministic N-1 criterion that is useful when making system reinforcement decisions. <p>The research work illustrated in this thesis indicates that the D-P criterion and associated procedures for bulk electric system analysis can be effectively utilized in bulk electric system reliability assessment. The conclusions and the techniques presented in this thesis should prove valuable to those responsible for composite generation and transmission system expansion planning.

The research presented in this thesis involves the study of ice cloud microphysical and optical properties using both hyperspectral and narrowband infrared spectral data. First, ice cloud models are developed for the Infrared Atmospheric Sounding Interferometer (IASI) instrument onboard the METOP-A satellite, which provide the bulk-scattering properties of these clouds for the 8461 IASI channels between 645 and 2760 cm-1. We investigate the sensitivity of simulated brightness temperatures in this spectral region to the bulk-scattering properties of ice clouds containing individual ice crystal habits as well as for one habit distribution. The second part of this thesis describes an algorithm developed to analyze the sensitivity of simulated brightness temperatures at 8.5 and 11.0 µm to changes in effective cloud temperature by adjusting cloud top height and geometric thickness in a standard tropical atmosphere. Applicability of using these channels in a bi-spectral approach to retrieve cirrus cloud effective particle size and optical thickness is assessed. Finally, the algorithm is applied to the retrieval of these ice cloud properties for a case of single-layered cirrus cloud over a tropical ocean surface using measurements from the Moderate Resolution Infrared Spectroradiometer (MODIS). Cloud top height and geometric thickness in the profile are adjusted to assess the influence of effective cloud temperature on the retrieval.

No description available.

No description available.

This thesis investigates some aspects of the inverse Compton scattering process within various physical contexts in high energy astrophysics. Initially an introduction to the key results of Comptonization theory for the case of scattering in optically thick plasmas is given, using a diffusion approach, since these results are required for the interpreta- tion of Comptonized spectra. Since Comptonization in astrophysical systems is frequently treated using numerical techniques, an introduction to these is then presented. Such linear Monte Carlo photon transport codes are typically applied to scattering in plasmas without temperature and density gradients. Additionally, treating bulk motion can be difficult even for simple cases. It is demonstrated that these problems can be made tractable numerically with the use of algorithms associated with non-linear Monte Carlo codes. Such codes can already treat scattering within arbitrary velocity structures in a plasma, and an extension of the algo- rithm is proposed that enables the easy calculation of photon transport in plasmas with non-constant density as well as non-constant temperature and/or bulk motion. This algorithm and code has been developed to treat scattering in astrophysical situations where bulk motion, temperature gradients and density gradients are simultaneously present in a plasma. Both a semi-analytic approach and the numerical approach are then used to treat Comp- tonization problems of current interest. Firstly, the standard two-phase disk-corona model for the high-energy spectra of Active Galactic Nuclei is modified to include an an outflow or wind which may provide an additional source of disk cooling. Earlier slab disk-corona models predict a spectral index which is consistent with observations only if all the accretion power is dissipated in the corona. For the models investigated here, energy spectral indices that are consistent with observations can be obtained with less accretion power being dissipated in the corona, as a result of an outflow/wind. However, it is required that the wind extract large amounts of power from the disk, and it it yet to be seen if this is a plausible scenario.

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 98-103).