Cargo revenue management for space logistics

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 79-82).This thesis covers the development of a framework for the application of revenue management, specifically capacity control, to space logistics for use in the optimization of mission cargo allocations, which in turn affect duration, infrastructure availability, and forward logistics. Two capacity control algorithms were developed; the first is based on partitioning of Monte Carlo samples while the second is based on bid-pricing with high-frequency price adjustments. The algorithms were implemented in Java as a plugin module to SpaceNet 2.0, an existing integrated modeling and simulation tool for space logistics. The module was tested on a lunar exploration concept which emphasizes global exploration of the Moon using mobile infrastructure. Results suggest that revenue management produces better capacity allocations in shorter duration missions, while producing nominal capacity allocations (i.e. those in the deterministic case) in the long run.by Nii A. Armar.S.M

Biocompatibility of cross-linked hyaluronate (Gel-200) for the treatment of knee osteoarthritis

SummaryObjectiveTo compare the biocompatibility and immunogenicity of two intra-articular hyaluronan formulations, Gel-200 (Gel-One®) and hylan G-F 20 (Synvisc® series).Experimental designA comparison of the biocompatibility of Gel-200 and hylan G-F 20 was made using a rat subcutaneous air pouch model and the knee joint of normal rabbits. Immunogenicity was evaluated using a homologous passive cutaneous anaphylaxis (PCA) assay in guinea pigs.ResultsIn the air pouch model in rats, characteristic fibrous belts formed in the subcutaneous tissue. Injection of hylan G-F 20 into the air pouch induced granulomatous nodules primarily composed of macrophages, multinucleated giant cells, and eosinophils accompanied with the test material in the center of the nodules in the fibrous belt. Furthermore, the thickness of the fibrous belt in the hylan G-F 20 group increased significantly compared to the saline group. Injection of Gel-200 into the air pouch induced neither granulomatous inflammation nor significant thickening of fibrous belt, while foamy macrophages containing the test material were observed. Intra-articular injection of hylan G-F 20 into the rabbit knee joints induced granulomatous inflammation, eosinophil infiltration, and significant increase in the number of cells in the synovial fluid, while these findings were absent in the Gel-200 group. In the immunogenicity assay, hylan G-F 20 induced a positive PCA reaction, but the Gel-200 did not.ConclusionGel-200 showed more favorable biocompatibility and less immunogenicity compared to hylan G-F 20. Gel-200 is expected to be a single injection hyaluronan product with less safety concerns for the treatment of knee osteoarthritis (OA) pain

Intensity-based image registration using multiple distributed agents

Image registration is the process of geometrically aligning images taken from different sensors, viewpoints or instances in time. It plays a key role in the detection of defects or anomalies for automated visual inspection. A multiagent distributed blackboard system has been developed for intensity-based image registration. The images are divided into segments and allocated to agents on separate processors, allowing parallel computation of a similarity metric that measures the degree of likeness between reference and sensed images after the application of a transform. The need for a dedicated control module is removed by coordination of agents via the blackboard. Tests show that additional agents increase speed, provided the communication capacity of the blackboard is not saturated. The success of the approach in achieving registration, despite significant misalignment of the original images, is demonstrated in the detection of manufacturing defects on screen-printed plastic bottles and printed circuit boards

Generating temperature cycle profiles of different solar photovoltaic module technologies from in-situ conditions for accurate prediction of thermomechanical degradation

The IEC61215 TC200 is a rigorous approval thermal cycling test process that assesses the reliability of solar photovoltaic modules and offers a 25-year lifetime guarantee. However, previous research has shown that installed solar photovoltaic modules experience different rates of degradation depending on the location and climate with most research focused on crystalline silicon. In this study, outdoor weathering data obtained from a rig set up in Kumasi, Ghana for the year 2014, is used to generate thermal cycles for 5 different technologies including monocrystalline, polycrystalline, and amorphous silicon, Copper Indium Gallium Selenide (CIGS) and Heterojunction-With-Intrinsic-Thin-Layer (HIT). From the results, the highest yearly average of the maximum and minimum temperatures, and ramp rates of 54.8oC, 26.1oC, and 6.05oC/h respectively are recorded in CIGS. Polycrystalline recorded the least temperatures of 45.2°C and 23.9°C while HIT recorded the least ramp rate of 4.45°C /h. A comparison between the 2014 and the IEC61215 thermal cycles show extremely wide differences which could explain the higher degradation rates and shorter life of installed solar photovoltaic modules. The procedure adopted in this research can be repeated at different locations to obtain technology-specific thermal cycling profiles to evaluate the thermomechanical damage and predict the life of different solar photovoltaic modules

Challenges of developing a peri-urban water supply strategy in Ghana

This paper discusses the efforts to fashion a strategy for peri-urban water supply in Ghana with financial support from Agence Francaise de Developpment. It posits that the institutional weakness of the Water Directorate of the erstwhile Ministry of Water Resources, Works and Housing as the policy formulation unit for the water sector created too much space for the Ghana Water Company Limited to abort the process for the successful implementation of the pilot project and the replication of an appropriate model. The paper however sees the creation of a new Ministry for Sanitation and Water Resources as an opportunity to strengthen the Water Directorate and the eventual development of an appropriate strategy for the peri- urban areas so as to minimise the problem of the missing middle