MathCAD model for the estimation of cost and main characteristics of air-cushion vehicles in the preliminary design stage

Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2005.Includes bibliographical references (p. 66-67).In the naval architecture terminology, the term ACV (Air Cushion Vehicle) refers to this category of vehicles, in which a significant portion of the weight (or all the weight) is supported by forces arising from air pressures developed around the craft, as a result of which they hover in close proximity to the sea. Major types are hovercrafts and SES (Surface Effect Ships). A well-designed Air Cushion Vehicle (ACV) is superior to a conventional ship, because it has less drag and requires less horsepower to operate at the same speed. An ACV is much more fuel-efficient than a ship with similar capacity or size. Rising fuel prices and shortages will make ACVs a desirable form of transportation in the future. In order to cover this future trend in marine transportation, a MathCAD model for the estimation of the main characteristics of Air Cushion Vehicles in the preliminary design stage is being developed. This model is based on a statistical analysis of the various parameters of existing crafts. For this reason, a statistical database has been created using publicly available information. A regression analysis has been performed using the data collected and the trend lines for every case have been derived.(cont.) For the validation of the code, LCAC (Landing Craft Air Cushion) is used as the reference vehicle. The values of LCAC design parameters that are known, are input in the code and crosschecked with the outputs. Iterative procedures have been applied to the code in order to correct the trend lines according to the reference model. The development of this MathCAD model is directly related to the lack of software dealing with the design of ACVs in the market. Conventional ship design tools are widespread and used even by students. On the other hand, ACV design programs are possessed by the companies that design this kind of crafts and are not widely available. In the following pages, together with the analysis of the model developed, the associated theory is presented so that the reader has a complete image of what an ACV is and how it works. Hence, this thesis is not a manual of a program, but a combination of theory and application intended to help the reader-user understand the design process of ACVs.by Georgios Gougoulidis.Nav.E.and S.M

Innovative decision-making methods for the preliminary design and operations of air-cushion and other marine vehicles

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 178-183).Ship design is a large-scale, multi-level, complex problem that requires decision-making at every stage of the design process. As such, it requires a great deal of time and resources. The evolution of the process of ship design has been relatively slow and is still based to a large extent on traditional methods that have been used for many decades. Evans' design spiral, which dates back to 1959, is the most characteristic example. These methods are reflected on the structure of various modem ship design software. However, these methods include inherent inefficiencies that need to be addressed. Some of them are the increased number of iterations, as well as the speed of execution of every iteration. The methods proposed in this dissertation try to alleviate such inefficiencies by introducing novel and easy-to-use approaches, including the formulation of new algorithms. Furthermore, concrete models are introduced in cases where there is no systematic approach to a problem. These approaches include both optimization and heuristic techniques. Neural networks belong to the first category, and although they have been used for small-scale marine problems, they haven't been extensively tested in a more general framework. Heuristics include methods such as the Mapping Model and the QuickEst algorithm, which are not found in marine applications. Heuristic methods are divided into quantitative and qualitative techniques. This research focuses on Air Cushion Vehicles since they are the newest type of advanced marine vehicles and their study is considered both tedious and challenging. However, the research also expands to other types of marine vehicles. Both design and operational aspects are examined as case studies. The results from these methods are cross-validated with other well-established and widely-used methods such as Multiple Linear Regression, proving the usefulness and validity of the considered methods.by Georgios Gougoulidis.Ph.D

Case Study: Atypical delta C-13 values of urinary norandrosterone

Isotope ratio mass spectrometry (IRMS) has been established in doping control analysis to identify the endogenous or exogenous origin of a variety of steroidal analytes including the 19-norsteroid metabolite norandrosterone (NorA). NorA can be found naturally in human urine in trace amounts due to endogenous demethylation or in situ microbial degradation. The administration of nortestosterone (nandrolone) or different prohormones results in the excretion of urinary NorA. Usually, this can be detected by IRMS due to differing delta C-13 values of synthetic 19-norsteroids compared to endogenous reference compounds. The consumption of uncastrated pig edible parts like offal or even meat may also lead to a urinary excretion of NorA. In order to determine the delta C-13 values of such a scenario, urine samples collected after consumption of a wild-boar-testicle meal were analyzed. IRMS revealed highly enriched delta C-13 values for urinary NorA, which could be related to the completely corn-based nutrition of the animal. Isotopic analysis of the boar's bristles demonstrated a dietary change from C-3-based forage, probably in winter and spring, to a C-4-based diet in the last weeks to months prior to death. These results supported the interpretation of an atypical test result of a Central European athlete's doping control sample with delta C-13 values for NorA of -18 parts per thousand, most probably caused by the consumption of a wild boar ragout. As stated before, athletes should be fully aware of the risk that consumption of wild boar may result in atypical or even adverse analytical findings in sports drug testing

Inhibition of bovine sperm-zona binding by bovine herpesvirus-1

The purpose of the present study was to identify a potential interference of bovine herpesvirus-1 (BoHV-1) with sperm-oocyte interactions during bovine in vitro fertilization. An inhibition of almost 70% of sperm-zona binding was observed when bovine cumulus-denuded oocytes were inseminated in the presence of 10(7) 50% tissue culture infective dose/ml BoHV-1. The inhibitory effect of BoHV-1 on sperm-zona binding was mediated by an interaction of the virus with spermatozoa, but not with oocytes. Treatment of spermatozoa with BoHV-1, however, did not affect sperm motility and acrosomal status. Antiserum against RoHV-1 prevented the virus-induced inhibition of sperm-zona binding, indicating that BoHV-1 itself affects the fertilization process. In order to investigate which BoHV-1 glycoprotein(s) are responsible for the virus-sperm interaction, BoHV-1 was treated with monoclonal antibodies against the viral glycoproteins gB, gC, gD and gH prior to insemination. Anti-gC completely prevented the inhibitory effect of BoHV-1 on sperm-zona binding, while anti-gD caused a reduction of this inhibition. Further evidence for the involvement of gC and gD in the virus-sperm interaction was provided by the fact that purified gC and gD decreased sperm-zona binding in a dose-dependent way with gC being more effective than gD. These results indicated that BoHV-1 inhibits bovine sperm-zona binding by interacting with spermatozoa. The binding of BoHV-1 to a spermatozoon is mediated by the viral glycoproteins gC and gD, and therefore seems to be comparable with the mechanisms of BoHV-1 attachment to its natural host cell