• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 5
  • 3
  • 3
  • 2
  • 1
  • Tagged with
  • 20
  • 5
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Comparing Methods for Measuring the Volume of Sand Excaveted by a Laboratory Cutter Suction Dredge Using an Instrumented Hopper Barge and a Laser Profiler

Manikantan, Arun 2009 December 1900 (has links)
The research focuses on the various methods that could be used in the laboratory to determine the values of production from a model cutter suction dredge. The values of production obtained from different methods are compared to estimate the best value. The tests were conducted in an attempt to pave the way to find spillage from the cutter suction dredge. The development of these methods is useful for evaluating the sediment spillage and residuals during dredging. The more accurate the values of production the more accurate would be the values of spillage. For this purpose, the laboratory dredge carriage and dredge/tow tank located at the Haynes Coastal Engineering Laboratory at Texas A&M University is used. During the summer of 2007 and 2008, the laboratory dredge carriage was used to dredge sand (d50 = 0.27 mm) in the sediment pit that is 7.6 m (25 feet) long, 3.7 m (12 feet) wide and 1.5 m (5 feet) deep. A laser profiler, a model hopper barge attached with pressure gauges, a flowmeter and density gauge aid in determining the production from the laboratory model of the cutter suction dredge were used. The before and after bathymetry measurements using a laser profiling system are used to determine the amount of sediment remaining after dredging. The hopper is instrumented with pressure gauges to measure the amount of sediment contained in the hopper. The laboratory dredge system has a magnetic flowmeter and nuclear density gauge that provide data to calculate the amount of sand delivered to the hopper. The difference between the sand volume from the before and after bathymetry is the amount of sand that is resuspended and subsequently resettles in the dredging area (residual) and the sand that is not picked up by the dredge (spillage). Many issues in laboratory testing were found during the course of testing and solutions were found. The production values are compared with reasoning as to why the differences occur. The results demonstrate the ability and difficulty of measuring the amount of material that is dredged and the amount of spillage and residuals that occurs during dredging.
2

Integrated applications of expert system and system simulation for oil-barge dispatching study - case of Kaohsiung Harbour

Chen, Ching-Chuan 18 July 2002 (has links)
The oil barge operation in Kaohsiung harbor is one of typical systems of resources allocation problems in a complex and dynamic environment. Such system is far more difficult to deal with than a static and deterministic system and often depends on experienced human experts for the oil barge assignment. One of the major dilemmas faced by the system is that decision makers do not know the managerial efficiency under the current dispatching mechanism. Besides, if the dispatching rules have been modified due to the resource variation in the future, how would the changes affect the system? The current research is trying to develop an evaluation system for oil barge assignment. The objective of the system is to evaluate the overall performances of the oil barge operation in Kaohsiung harbor. Both expert system and system simulation techniques would be applied for such analysis. To acquire the current heuristic of oil barge assignment and then transfer it to a rule-based knowledge in an expert system, the interview with the engineer, who is responsible for making such decision, is the crucial step. With the knowledge base and the reasoning mechanism available, it is possible to imitate the current oil barge assignment. To further evaluate the performance of such assignment rule, the current research has developed the system simulation model of oil barge operation. This model is able to quantify the service quality under various assignment scenarios. The results of simulation can further be presented to the decision makers with easy-understanding animations. The case study would focus on Kaohsiung harbor¡¦s oil barge operation. The integrity and suitability of the expert system and simulation model have been validated through extensive statistical analysis. At last, various scenario analysis based on such integrated models have been conducted to improve the current oil barge operation and to set the appropriate response plans confronted by the future development of Kaohsiung harbor as the Asia-Pacific transshipment center.
3

Analysis of Barge Impact with Bridge Pier

Miller, Anna Marie 17 August 2013 (has links)
The Mississippi River Bridge in Vicksburg, MS is a 7 span cantilever bridge that is 3,389 feet long by 68.5 feet wide and is part of the Interstate-20 corridor. On March 23, 2011 at 1:30pm, a barge moving downstream struck a pier of the bridge. Infrasound stations located at the U.S. Army Engineer Research and Development Center (ERDC) detected the impact. Coincidentally, ERDC had instrumented the bridge with strain gages and accelerometers as part of a structural health monitoring project. Finite Element (FE) models were developed to investigate the structural behavior of the bridge due to the impact. The measurements and the FE models were used to determine the source mechanism of the infrasound from the bridge. Measurements from the sensors that were installed on the bridge will be presented along with FE models and infrasound data.
4

Analysis of coupled body mooring and fender system

Girija Sasidharan Pillai, Harish 01 November 2005 (has links)
The hydrodynamic excitation and response behavior of multi-body systems with varying degrees of coupling presents many challenges for designers of offshore structures. In this study, attention is focused upon the analysis and interpretation of experimental data obtained for an unmanned deepwater mini-Tension Leg Platform (mini-TLP) coupled to a tender barge. Each body has its own mooring system and the bodies are connected by two breast lines extending from central points on the mini-TLP to central points on the bow and stern of the tender barge. A fender system is located between the two platforms. Thus the two floating bodies are constrained to move together in surge and yaw while they are free to move independently in heave, roll and pitch with some limitations on sway. The data of the individual records are characterized using statistical moments, including skewness and kurtosis, to examine the degree of non-Gaussian behavior. Correlation analysis and cross spectral analysis are used to investigate the relationships between selected measurements such as the motion of each vessel, tensions in the mooring lines and tendons and the forces on the fenders. The analysis shows that the coupling effects reduce the mooring line and tendon tensions significantly and that the motions of the two vessels influence the line tensions and fender forces. The data distribution patterns followed by the parameters and the corresponding extreme values are also investigated.
5

Identifying Factors and Quantifying their Impact on Transportation Costs of Pre-Processes Biomass

Gonzales, Daniela Sofia 11 August 2012 (has links)
This research presents a rail transportation cost analysis of bulk agricultural commodities (such as grain and wood chips) with similar characteristics as pre-processed biomass. This study analyzes the cost factors that affect rail pricing for shipments of bulk-commodities (such as grain) from the Midwest to various regions in the US using regression analysis theories. The rail cost equations developed from the regression analysis were used to compare the trade-offs that exist between truck, rail and barge transportation of pre-processed biomass.
6

Contribution à l'optimisation du chargement et du déchargement des conteneurs dans le cas des transports routier et fluvial / Contribution to the optimization of loading and unloading og containers in the case of road and river transport

El Yaagoubi, Amina 19 January 2019 (has links)
Dans ce mémoire, nous nous intéressons à l’optimisation des mouvements improductifs de chargement/déchargement, appelés shiftings, dans les problèmes de transport. Dans le premier contexte,nous introduisons le problème de shifting dans le cas du voyageur de commerce. Notre objectif est de chercher un circuit hamiltonien qui optimise à la fois le coût distance et le coût shifting. Nous proposons une modélisation mathématique du problème, puis, nous adaptons la métaheuristique d’optimisation par colonies de fourmis sous sa forme séquentielle et parallèle pour le résoudre. Dans le deuxième contexte, nous abordons le problème d’optimisation des plans de chargement et d’arrimage des conteneurs dans des barges. Ce problème consiste à chercher l’emplacement le plus convenable de chaque conteneur dans les barges de façon à faciliter son déchargement dans la chronologie des ports à visiter. D'abord, nous introduisons une modélisation mathématique du problème dans le cas d’une seule barge ou différents ports du trajet ont des coûts shiftings non-uniformes. L’objectif est d’optimiser le coût total de shiftings, la stabilitélongitudinale de la barge et celle transversale. Ensuite, nous généralisons le problème au cas d’un système de convoi de barges. Nous proposons, d’abord, un modèle mathématique en nombres entiers, dans lequel, nous considérons l’aspect multi-objectif en optimisant le nombre de shiftings, la stabilité du convoi et le nombre de barges utilisées dans le convoi. Puis, nous adaptons la méthode nsga-II en se basant sur les heuristiques du problème de bin-packing.L'ensemble des résultats obtenus est évalué en utilisant des mesures de performances adaptées au problème. / This work outlines the optimization of unproductive loading/unloading movements, called shiftings, in transport problems. in the first context, we introduce the shifting in the case of the traveling salesman problem. our goal is to find a hamiltonian circuit that optimizes both distance and shifting costs. we propose a mathematical modeling of the problem, and then we adapt the ant colony optimization metaheuristic in its sequential and parallel form to solve it. in the second context, we address the 3d container stowage planning problem of barges. this problem consists in finding the most suitable location of each container in the barge in order to facilitate its retrieval in the chronology of ports to be visited. firstly, we introduce a mathematical modeling of the problem in the case of a single barge where different ports are of non-uniform operational costs. the main objective is to optimize the total shiftings fees, the longitudinal stability of the barge and the transverse one. then, we generalize our problem to the case of barge convoy systems. we first propose a suitable mathematical modeling, in which, we consider the multi-objective aspect by optimizing the total number of shiftings, the convoy stability and the number of the real-used barges in the convoy. in order to solve this new variant, we propose a novel adaptation of the multi-objective evolutionary algorithm nsga-ii (non-dominated sorting genetic algorithm-ii) based on a set of heuristics introduced by the bin-packing problem resolution methods. the numerical results are evaluated using performance measures adapted to theproblem.
7

MODELING, SIMULATION AND ANALYSIS OF MULTI-BARGE FLOTILLAS IMPACTING BRIDGE PIERS

Yuan, Peng 01 January 2005 (has links)
The current design code governing bridge structure resistance to vessel impact loads in the U.S. is the American Association of State Highway and Transportation Officials' (AASHTO) Guide Specification and Commentary for Vessel Collision Design of Highway Bridges. The code stipulated method, based on Meir-Dornberg's equivalent static load method, is usually not warranted because of insufficient data on the impact load histories and wide scatter of the impact force values. The AASHTO load equations ignore certain fundamental factors that affect the determination of impact forces and bridge dynamic responses. Some examples of factors that are omitted during standard impact force analysis are: impact duration, pier geometry, barge-barge and barge-pier interactions, and structural characteristics of bridges. The purpose of this research is to develop new methods and models for predicting barge impact forces on piers. In order to generate research information and produce more realistic flotilla impact data, extensive finite element simulations are conducted. A set of regression formulas to calculate the impact force and time duration are derived from the simulation results. Also, a parametric study is performed systematically to reveal the dynamic features of barge-bridge collisions. A method to determine the quasi upper bound of the average impact force under any given scenarios is preposed. Based on the upper bounds of the average impact forces, an impact spectrum procedure to determine the dynamic response of piers is developed. These analytical techniques transform the complex dynamics of barge-pier impact into simple problems that can be solved through hand calculations or design charts. Furthermore, the dependency of the impact forces on barge-barge and barge-pier interactions are discussed in detail. An elastoplastic model for the analysis of multi-barge flotillas impacting on bridge piers is presented. The barge flotilla impact model generates impact force time-histories for various simulation cases in a matter of minutes. The results from the proposed model are compatible with the respective impact time-histories produced by an exhuaustive finite element simulation. All of the proposed methods and loading functions in this study are illustrated through design examples. Accordingly, the research results may help engineers to enhance bridge resistance to barge impacts and also lead to economic savings in bridge protection design.
8

Characterization of coupled body response in random sea

Xie, Chen 25 April 2007 (has links)
The frequent use of two or more closely positioned vessels during offshore operations makes the study of multi-body hydrodynamics an important topic, especially for the design of deepwater offshore systems. This research investigation studies the response behavior of a coupled mini-TLP / barge system in both head and beam sea conditions. The design sea conditions were selected to represent the combined wind, wave and current conditions for a target location off the coast of West Africa. Both the mini-TLP and the barge were designed to have independent mooring systems. Coupling between the two vessels is introduced through a connection consisting of two breast lines and a fender system. This connection is designed to restrain the horizontal movements of the two vessels while keeping a constant distance between them and avoiding collisions. The main focus of this study is to analyze the experimental data obtained during the model testing, especially the motions of the two bodies and the values related to the fender system, in order to characterize the behavior of the uncoupled and coupled system configurations. A statistical approach is used for the data analysis and interpretation. Statistical parameters are used to provide an overall characterization of system behavior, and Gaussian and Weibull distribution functions are utilized to detect the importance of non-linearity in the data with particular attention to extreme values. Correlations between the two vessels in time domain and frequency domain are investigated. In addition, auto and cross spectrum analyses of the data are used to contrast the motion behavior of the uncoupled and coupled configurations. It is shown that the connection system reduces the horizontal vessel motions; however the forces exerted on the fender system show significant variation depending on sea heading conditions.
9

Economic Value, Resiliency and Efficiency of Inland Waterway Freight Transport in the Ohio River Basin

DiPietro, Gwen Shepherd 01 September 2014 (has links)
This dissertation examines the resiliency, efficiency, and environmental impact of barge shipments within the upper Ohio River basin, contrasting findings relevant to this region with assumptions and findings of broader national studies and providing alternative assessment methods. The unique attributes of this region’s inland waterways infrastructure and usage patterns are dominated by the shipment of coal; mines and powerplants with heavy and inflexible dependence on barge shipments; and the constrictions of the waterway infrastructure. Acknowledging these attributes allows for a more accurate assessment in the future of risks due to infrastructure failure and opportunities for efficiency gains. Research goals were set in three major areas: assessing the impact of an extended loss of commercial river navigation due to catastrophic infrastructure failure; assessing current and potential new efficiency metrics for inland waterways freight movement, both in terms of vessel movements and the infrastructure itself; and quantifying and assessing air emissions from regional commercial river traffic. The first research goal was to assess the impact of an extended loss of commercial river navigation due to catastrophic infrastructure failure. The objectives of this research goal were to develop a failure scenario; to develop methodologies to identify at-risk commodity shipments, feasible alternate modes of transportation, supply chain options, and shipping costs; and to develop a methodology to assess the potential closure of facilities impacted by infrastructure failure. A hypothetical failure scenario was assessed for a year-long closure of the Monongahela River between Charleroi and Elizabeth in 2010. For this scenario, the potentially displaced volume of coal shipments from mines to powerplants for a hypothetical river shutdown in 2010 was estimated at 7.0 million tons. The resilience of the impacted facilities, the feasibility of their shipping alternatives, and their ability to re-organize into new markets were assessed, showing heavy predicted impacts for facilities within the hypothetical failure zone, minimal impacts on facilities located below the failure zone, and mixed impacts above the failure zone that depend on facility-specific shipping mode alternatives. Lost revenues were estimated for facilities that close due to an inability to adapt, as well as the replacement cost of towboats and barges trapped by a catastrophic and sudden failure. The aggregate costs to these facilities as a result of a year-long closure in 2010 were estimated at $0.56-1.7 billion. The second research goal was to assess commonly used and potential new efficiency metrics for the inland waterways. Objectives of this goal included the development of methodologies to identify, characterize, and differentiate between vessel and commodity trips; to assess efficiency metrics currently used by USACE and develop improved metrics; and to conduct stochastic time studies of commodity trips to quantify efficiency gains from infrastructure improvements. The vessel and commodity trip analyses provide a unique assessment of the inefficiencies created by the infrastructure bottlenecks within the region. Data from USACE’s Lock Performance Monitoring System and the Energy Information Administration’s Survey 923 were used to characterize and rank the vessel and commodity trips made in 2010 in terms of frequency, tonnage, and ton-miles. Such rankings can be used to prioritize optimization projects and to assess usage patterns. The analyses of various efficiency measures commonly used for the inland waterways were conducted in light of the particular constraints of operation within the upper Ohio River basin. These upriver locks differ in size, requiring vessel operators to optimize the type and configuration of barges used within the region, and causing the regional profile to differ from fleet and flotilla profiles generated at a national level or for other regions. Consideration of these differences allows for more accurate analysis of usage patterns, with implications for efficiency considerations of time and fuel consumption. Stochastic modeling of historical usage patterns allows for the comparison of time requirements with different flotilla configurations and with different infrastructure configurations. A scenario analysis on a typical regional shipment between a coal mine and powerplant was used to demonstrate the method. Results show that completion of a long delayed lock reconstruction project will reduce the time required, and thus the cost and fuel, to move commodities across the region. The savings for a 15-jumbo barge tow moving 200 miles across the study area was estimated to be 17% as a result of completion of the Lower Mon Project. The third research goal was to quantify and assess the regional impact of commercial river traffic on air quality. The specific objectives of this goal were to develop a methodology for calculating emission loadings; and to develop a methodology to assess the impact of vessel emissions on regional air monitors. An estimation of particulate emissions from the vessels’ diesel engines is presented, showing total releases of PM2.5 to be about 360 tons in 2010 across 600 river miles of the upper Ohio River basin, on the same order of magnitude as the major point source releases reported in Allegheny County, and about 25% of releases from a typical 1,700 MW regional powerplant. A screening analysis estimates PM2.5 concentrations attributable from towboats passing through the Liberty-Clairton non-attainment region, predicting that these emission levels would be orders of magnitude below the detection limits of the region’s air monitors, and would be dwarfed by the point source impacting those monitors.
10

Three Essays on Waterborne Transportation

Alshareef, Mohammed Hamed January 2019 (has links)
This dissertation introduces three different topics on waterborne transportation. River transportation is a very important alternative for freight shipments in some countries. A significant portion of United States agricultural commodities transported via river barges. The lower portion of the Missouri River has been channelized to support barge traffic. Barge traffic has been used to move agricultural commodities to the Gulf of Mexico through Mississippi River to be exported overseas. Missouri River faced some weather issues such as drought in some years and flooding in others. Alternative transportation modes are important during the post-harvest period when the river has low-flow. The results showed a positive cost to agricultural freight in three years of a five years in dry period. In the other two years rail rates were estimated to be lower than barge rates. The second topic is using maritime distance to measure trade costs in agriculture. Maritime transportation holds an important position among other transportation means because it has some characteristics that others do not. Maritime shipping is critical to international trade because of the advantages that ships have by carry huge amounts of cargo for long distances. The impact of port-to-port maritime distance on US international trade to Europe and North and South America was tested. Unexpectedly result shows that trade increases with maritime distance. This impact decreases when the geographical distance is higher than the maritime distance. The third paper measures the efficiency and productivity of major Middle East container ports. Ports considered the main node to link the trading partners. The results indicate that eight ports out of 21 ports have low productivity. / Saudi Arabia Cultural Mission, USA / King Abdulaziz University / Faculty of Maritime Studies, Jeddah, Saudi Arabia

Page generated in 0.0486 seconds