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Full-Text Articles in Mechanical Engineering

Integration Of Inboard Propulsion In Shock Mitigating Membrane Hull Technology, Korrey Rotkiske Dec 2019

Integration Of Inboard Propulsion In Shock Mitigating Membrane Hull Technology, Korrey Rotkiske

Theses and Dissertations

Membrane Hull Technology is a strength based marine vessel design concept that seeks to utilize the in-plane properties of fiber reinforced composites to generate a lighter weight vessel with inherent shock mitigation benefits. MHT has been applied on several Naval crafts yet the design features of inboard propulsion systems have not been addressed. Inboard propulsion systems are a very common form of propulsion used in many types of marine vessels especially larger vessels. This thesis seeks to overcome the inboard engine mounting challenges of MHT which limits use of this technology in the marine industry. The fundamental design elements of …

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Numerical Simulations Of Comprehensive Hydrodynamic Performance Of Darpa Suboff Submarine, Kenshiro Takahashi Dec 2019

Numerical Simulations Of Comprehensive Hydrodynamic Performance Of Darpa Suboff Submarine, Kenshiro Takahashi

Theses and Dissertations

A numerical study of the DARPA SUBOFF model using computational fluid dynamics (CFD) has been presented for developing a CFD application procedure to compute the hydrodynamic performance of underwater vehicles, including submarines. Several configurations, such as bare hull, fairwater, sterns, and/or ringwing-appended hulls, were examined for the straight-ahead, steady translation and turning, and self-propelled conditions. A systematic study was conducted to ensure an adequate computational domain expansion and reasonable prism layer mesh properties for solutions independent of the parameters. The hydrodynamic forces exerted on the hull and the appendages were verified and validated in accordance with a published methodology under …

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Deficiencies In The Physics Of Existing Operational Wave And Surge Models, D. T. Resio Oct 2019

Deficiencies In The Physics Of Existing Operational Wave And Surge Models, D. T. Resio

Ocean Waves Workshop

No abstract provided.

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A New Real-Time Ocean Observing Station On Ship Shoal On Louisiana Shelf, Chunyan Li, Peter Luo, Brian Milan, Wei Huang Oct 2019

A New Real-Time Ocean Observing Station On Ship Shoal On Louisiana Shelf, Chunyan Li, Peter Luo, Brian Milan, Wei Huang

Ocean Waves Workshop

One of the major challenges that we are facing in the northern Gulf of Mexico coastal area is the need of a better and reliable offshore met-ocean real time data collection system that supports the mission of Bureau of Ocean Energy Management (BOEM) and other federal and local agencies for coastal management, protection, and restoration, especially along the Louisiana coast. This area has a suite of environmental problems that require the acquisition of real time data for immediate assessment or model-based assessment and predictions that rely on this kind of data. One such system providing this kind of data is …

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Update In Us Navy Global Wave Model Forecasting, J. D. Dykes, W. E. Rogers, D. Wang Oct 2019

Update In Us Navy Global Wave Model Forecasting, J. D. Dykes, W. E. Rogers, D. Wang

Ocean Waves Workshop

No abstract provided.

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Ocean Waves Workshop 2019 Session 2 Notes, Kaus Raghukumar, Sam Mcwilliams Oct 2019

Ocean Waves Workshop 2019 Session 2 Notes, Kaus Raghukumar, Sam Mcwilliams

Ocean Waves Workshop

No abstract provided.

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Directional Spectrum Measurements By The Spotter: A New Developed Wave Buoy, Kaus Raghukumar, Grace Chang, Frank Spada, Tim Jannsen Oct 2019

Directional Spectrum Measurements By The Spotter: A New Developed Wave Buoy, Kaus Raghukumar, Grace Chang, Frank Spada, Tim Jannsen

Ocean Waves Workshop

The Spotter is an accurate, low-cost, easily deployable and robust solar powered wave buoy recently developed by Sofar Technologies (formerly Spoondrift). Spotter reduces costs and complexity of surface wave and current measurements, which can be useful for academic, military, and commercial research into surface wave and wave-driven dynamics. We performed a series of validation tests and research experiments with the Spoondrift Spotter. The low-cost and compact Spotter makes it easy to deploy arrays of wave buoys which was previously not feasible (or cost prohibitive) with traditional wave buoys. A well-designed array can provide a direct measurement of the directional wave …

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Innovations In Metocean Sensors, Pieter Smit, T. T. Janssen Oct 2019

Innovations In Metocean Sensors, Pieter Smit, T. T. Janssen

Ocean Waves Workshop

Real-time observations are critical to understand, predict and estimate the impact of extreme weather events such as extratropical hurricanes and storms. Remote sensing, moored wave buoys and advances in predictive models have greatly advanced understanding and predictive capability of extreme ocean weather. However, due to cost and complexity of traditional moored buoys, in-situ networks are typically sparse and often close to shore and not well suited to drive predictive models over meaningful geophysical scales. Here we will discuss ongoing efforts to extend the capability of the Sofar Spotter to measure marine boundary layer dynamics. With the advancement to more portable …

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Ndbc Ocean Wave Observation System Update, Rodney Riley, Randy Stewart, Steven Dinapoli Oct 2019

Ndbc Ocean Wave Observation System Update, Rodney Riley, Randy Stewart, Steven Dinapoli

Ocean Waves Workshop

The U.S. National Oceanic and Atmospheric Administration’s (NOAA) National Data Buoy Center (NDBC) is modifying its ocean wave observation system due to parts obsolescence. The modified system is named Ocean Wave Linux (OWL). OWL will replace the NDBC’s older and now obsolete Digital Directional Wave Module (DDWM). Once OWL completes operational verification, the DDWM will be phased out of the NDBC’s operational weather buoy network.

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Pressure Effect On An Ocean-Based Humidification-Dehumidification Desalination Process, Yingchen Yang Oct 2019

Pressure Effect On An Ocean-Based Humidification-Dehumidification Desalination Process, Yingchen Yang

Mechanical Engineering Faculty Publications

A new humidification-dehumidification (HDH) desalination process is proposed and analyzed. Being ocean based, the process does not produce any brine. It is largely powered jointly by solar energy, wind energy, and various types of ocean energies in a nearly natural way. A vacuum pump is employed to drive the air circulation throughout the HDH process. It is the only unit that consumes electricity. The HDH process is analyzed under various conditions, including using a low pressure (as low as to 0.2 atm) for humidification and the ambient pressure for dehumidification, running the entire HDH process around a low pressure (as …

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Numerical Modeling Of Shoreline Response To Storm Tides And Sea Level Rise, Akash Sahu Oct 2019

Numerical Modeling Of Shoreline Response To Storm Tides And Sea Level Rise, Akash Sahu

Civil & Environmental Engineering Theses & Dissertations

In this study, an integrated hydrodynamic, wave, and sediment transport modeling approach is developed for predicting the spatiotemporal variation of erosion of a sandy shoreline due to storm surge, wave action, tidal variations, and relative sea level rise (RSLR). The study site is located at the northern most portion of the city of Norfolk, Virginia, and it is of importance to the city, both in terms of tourism and for the protection that it provides for upland properties against storms. The region, in general, experiences the highest rate of RSLR on the U.S. East Coast which should result in high …

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Dynamic Response Modeling Of High-Speed Planing Craft With Enforced Acceleration, Gene Hou, Brain Johnson, Jonathan Degroff, Steven Trenor, Jennifer Michaeli Oct 2019

Dynamic Response Modeling Of High-Speed Planing Craft With Enforced Acceleration, Gene Hou, Brain Johnson, Jonathan Degroff, Steven Trenor, Jennifer Michaeli

Mechanical & Aerospace Engineering Faculty Publications

An approach is investigated in this study for structural dynamic analysis of a high-speed planing hull, in which the pointwise acceleration data collected from sea trials are enforced as base excitation. The paper first performed the full boat analysis of an 11-meter high speed craft for a period of one wave impact selected from each of nine seakeeping runs. The sea trial acceleration data collected from 11 accelerometers placed close to the centerline and the keel are enforced as input, while those from 3 accelerometers placed around the pilot cabin are selected for validation. The substructure dynamic analysis of the …

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Sensor Development To Utilize Underwater Electric Potential (Uep) Fields To Navigate The Underwater Areas Of Ship Hulls, Caglar Erdogan Sep 2019

Sensor Development To Utilize Underwater Electric Potential (Uep) Fields To Navigate The Underwater Areas Of Ship Hulls, Caglar Erdogan

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Underwater electric potential fields occur due to natural reasons, such as changes in atmosphere, ionosphere, magnetosphere, and movements of water bodies in the ocean, or artificial reasons, such as stray and controlled electric currents, or both. Electric potential fields around ship hulls are mainly generated due to corrosion protection systems and dissimilar materials. The electric field intensity over an impressed current anode of a large cruise ship operating in with seawater with a resistance of 20 0-cm is around 90 mV/cm, whereas it is between 0.4 and 1 mV/cm on a propeller for the same ship. The theoretical field intensities …

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Protective Effect Of An Ice-Breaking Structure On Offshore Structures In Shallow Waters, Ji-Wu Dong, Zhi-Jun Li, Xiang-Peng Kong, Xiao-Dong Liang Aug 2019

Protective Effect Of An Ice-Breaking Structure On Offshore Structures In Shallow Waters, Ji-Wu Dong, Zhi-Jun Li, Xiang-Peng Kong, Xiao-Dong Liang

Journal of Marine Science and Technology–Taiwan

In this study, an ice-breaking structure (IBS) was designed to break large ice floes into small fragments through flexural failure predominantly for protecting offshore structures in shallow waters. The protective effect of the IBS on a vertical isolated cylindrical pile (ICP), which was examined through the model tests of the crushing ice loads and collision forces on the ICP from ice pieces broken with the IBS under identical conditions, was evaluated by obtaining the relative difference between the maximum values of the horizontal crushing forces and collision loads on the ICP. The results indicated a notable protective effect of the …

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Surface Kinetic Energy Distributions In The Global Oceans From A High-Resolution Numerical Model And Surface Drifter Observations, Xiaolong Yu, Aurelien Ponte, Shane Elipot, Dimitris Menemenlis, Edward Zaron, Ryan Abernathey Aug 2019

Surface Kinetic Energy Distributions In The Global Oceans From A High-Resolution Numerical Model And Surface Drifter Observations, Xiaolong Yu, Aurelien Ponte, Shane Elipot, Dimitris Menemenlis, Edward Zaron, Ryan Abernathey

Civil and Environmental Engineering Faculty Publications and Presentations

The surface kinetic energy of a 1/48◦ global ocean simulation and its distribution as a function of frequency and location are compared with the one estimated from 15,329 globally distributed surface drifter observations at hourly resolution. These distributions follow similar patterns with a dominant low-frequency component and well-defined tidal and near-inertial peaks globally. Quantitative differences are identified with deficits of low-frequency energy near the equator (factor 2) and at near-inertial frequencies (factor 3) and an excess of energy at semidiurnal frequencies (factor 4) for the model. Owing to its hourly resolution and its near-global spatial coverage, the array of surface …

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A Study Of The Electron Regeneration Efficiency Of Solar Cells Fabricated Using Cmc/Pva-, Alginate-, And Xanthan-Based Electrolytes, Nur Farha Shaafi, Saifful Kamaluddin Muzakir, Bouchta Sahraoui Aug 2019

A Study Of The Electron Regeneration Efficiency Of Solar Cells Fabricated Using Cmc/Pva-, Alginate-, And Xanthan-Based Electrolytes, Nur Farha Shaafi, Saifful Kamaluddin Muzakir, Bouchta Sahraoui

Makara Journal of Technology

A photovoltaic (PV) mechanism consists of three important steps, i.e., (i) electron excitation upon absorption of photon with energy higher than the bandgap of fluorophore, (ii) excited-state electron injection from the fluorophore to the pho-toelectrode, and (iii) electron regeneration from the electrolyte to the fluorophore. An efficient electron regeneration could be achieved upon fulfillment of the requirements of energy alignment, i.e., lowest unoccupied molecular orbital of fluorophore (LUMOfluorophore) > redox potential of electrolyte > highest occupied molecular orbital of fluorophore (HOMOfluorophore). This study investigated the electron regeneration efficiency of excitonic solar cells fabricated using three polymer-based electrolytes, i.e., (i) 60% carboxymethyl cellulose …

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Use Of The “Dnachecker” Algorithm For Improving Bioinformatics Research, Nausheen Bhat, Ezra Bernadus Wijaya, Arli Aditya Parikesit Aug 2019

Use Of The “Dnachecker” Algorithm For Improving Bioinformatics Research, Nausheen Bhat, Ezra Bernadus Wijaya, Arli Aditya Parikesit

Makara Journal of Technology

Basic Local Alignment Sequencing Tool (BLAST) is a bioinformatics tool used for analyzing nucleotide sequences with regards to their similarity. BLAST can be found online on biological databases such as the National Center for Biotechnology Information (NCBI) and other such repositories. The mechanism of BLAST allows the target sequence to be compared with other sequences to find regions of local similarity, and thus, a comparability quotient that determines the resemblance between the sequences is created. Due to the open-platform nature of the online databanks, several sequences can be accepted with little to no interjections regarding the quality of sequence submitted. …

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Study Of Ecological Design Of Residential Complexes Using Spss To Elevate Resident Satisfaction, Soheil Malekpour Kolbadinejad, V. Malekpour Ravasjan, A. Darvish Aug 2019

Study Of Ecological Design Of Residential Complexes Using Spss To Elevate Resident Satisfaction, Soheil Malekpour Kolbadinejad, V. Malekpour Ravasjan, A. Darvish

Makara Journal of Technology

This article reports the general residential satisfaction, affecting ecological factors, and their importance in area in Tehran. The collected field data was analyzed using SPSS. Cronbach's alpha variable was used to determine the reliability of the questionnaire and the Friedman test was used to assess priorities that influence residential satisfaction. The results show that the quality of residential environments and general satisfaction of their residents may be enhanced by identifying these criteria and making appropriate plans for their improvement.

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Adsorption Of Heavy Metal Ions By Oil Palm Decanter Cake Activated Carbon, Mohd. Ezreeza Mohamed Yusoff, Juferi Idris, Nahrul Hayawin Zainal, Mohamad Faizal Ibrahim, Suraini Abd-Aziz Aug 2019

Adsorption Of Heavy Metal Ions By Oil Palm Decanter Cake Activated Carbon, Mohd. Ezreeza Mohamed Yusoff, Juferi Idris, Nahrul Hayawin Zainal, Mohamad Faizal Ibrahim, Suraini Abd-Aziz

Makara Journal of Technology

Adsorption processes are widely used for the removal of heavy metals from waste streams. Oil palm decanter cake (OPDC) is used as a bioadsorbent because of its compositional properties for activated carbon production; moreover, it is a readily available raw material produced in palm oil mills and is thus abundant and cheap. In this study, the OPDC was carbonized at 700 °C and activated using steam at 700 °C to produce oil palm decanter cake activated carbon (AC-OPDC). Batch adsorption experiments were carried out to compare the adsorption capacities of the raw OPDC and the AC-OPDC for heavy metals removal. …

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Experimental Evaluation Of Three Different Humidity Conditions To Physical And Mechanical Properties Of Three Different Mixtures Of Unfired Soil Bricks, Heru Purnomo, Srikandi Wahyu Arini Aug 2019

Experimental Evaluation Of Three Different Humidity Conditions To Physical And Mechanical Properties Of Three Different Mixtures Of Unfired Soil Bricks, Heru Purnomo, Srikandi Wahyu Arini

Makara Journal of Technology

Unfired brick is considered as a more environmentally friendly material than fired brick. It has lower mechanical properties than that of fired brick where humidity influences both bricks. Physical and mechanical properties of unfired bricks made of three kinds of mixtures were studied experimentally under three humidity conditions. The first kind of unfired brick was made only with soil and water while the second type was made of a mixture of soil, water and lime, and the third type was a mixture of soil, water, lime and uniform treated coir where 4% of lime mass was substituted with coir mass. …

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Component Analysis And Antiangiogenic Activity Of Thailand Stingless Bee Propolis, Eriko Ishizu, Sari Honda, Tosihro Ohta, Boonyadist Vongsak, Shigenori Kumazawa Aug 2019

Component Analysis And Antiangiogenic Activity Of Thailand Stingless Bee Propolis, Eriko Ishizu, Sari Honda, Tosihro Ohta, Boonyadist Vongsak, Shigenori Kumazawa

Makara Journal of Technology

Propolis is a natural resin produced by honey bees from certain plants, has gained popularity as a food and alternative medicine. However, to the best of our knowledge, few studies on native Thailand stingless bee propolis are available. Information on the chemical composition and biological activities of propolis is needed to investigate its potential utility. Recently we have reported the possible plant origin of Thailand stingless bee propolis, Garcinia mangostana. In this study, further component analysis, functional evaluation, and identification of the plant origin of Thailand stingless bee propolis are conducted. Nine xanthones, including α-mangostin, garcinone C, γ-mangostin, cochinchinone T, …

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3d Fdtd Method For Modeling Of Seismo-Electromagnetics Disturbance On Crustal Earth, Nabila Husna Shabrina, Yasuhide Hobara, Achmad Munir Aug 2019

3d Fdtd Method For Modeling Of Seismo-Electromagnetics Disturbance On Crustal Earth, Nabila Husna Shabrina, Yasuhide Hobara, Achmad Munir

Makara Journal of Technology

The paper deals with the modelling of seismo-electromagnetics disturbance on the crustal earth by use of threedimensional (3D) finite-difference time-domain (FDTD) method. The model is built up by discretizing the frontier geographical region between Java Island and Sumatra Island in a cylindrical coordinate system-based 3D object. The proposed method is applied to compute and analyze electromagnetics (EM) fields of the observed very low frequency (VLF) wave used for the investigation. Boundary condition of uniaxial perfectly matched layer (UPML) are applied surrounding the area of computation for truncating the object of simulation. The investigation are focused on the propagation time of …

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A Coastal Estuarine Ensemble Forecasting System, Peyman Taeb Jul 2019

A Coastal Estuarine Ensemble Forecasting System, Peyman Taeb

Theses and Dissertations

This research has been conducted in an effort to reduce the computational costs associated with high-resolution coastal estuarine modeling in ADCIRC. It was proposed that model scalability will be significantly enhanced if the conventional single-domain technique is replaced by a nesting method. Preliminary testing indicated the potential for 50% to more than 80% simulation runtime reduction (depending on the study site) by implementing a nesting technique. Once the concept was proved, the development of an operational, ensemble-based forecasting system, exclusively for the east coast of Central Florida and the IRL system, was implemented. The system, referred to as Ensemble Multistage, …

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Advancing Numerical Calculation Of Mixed Sized Sediment Transport And Morphology Change, Irene Margaret Watts Jul 2019

Advancing Numerical Calculation Of Mixed Sized Sediment Transport And Morphology Change, Irene Margaret Watts

Theses and Dissertations

Numerical modeling of sediment transport and morphologic change has become a powerful tool for studying and working in the coastal zone. Numerical calculation can assist in a broad range of projects from regional sediment management to beach nourishment as well as evaluating environmental aspects of dredging and placement and implications to water quality and turbidity. Success in application of these tools is partially dependent on the quality of characterization of the sediments in the field. These parameters could include grain size, mineralogical composition, specific gravity and fall velocity. Sediment transport formulations are sensitive to the spatial representation of the sediments …

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The Effect Of Hydro-Meteorology On Ship Collision Avoidance In Heavy Traffic Areas With A Simplified Simulation Model, Ming-Chung Fang, Kun-Yuan Tsai, Chih-Chung Fang Jun 2019

The Effect Of Hydro-Meteorology On Ship Collision Avoidance In Heavy Traffic Areas With A Simplified Simulation Model, Ming-Chung Fang, Kun-Yuan Tsai, Chih-Chung Fang

Journal of Marine Science and Technology–Taiwan

On the basis of the ship collision avoidance steering system in calm water developed by the authors, this paper upgrades the numerical simulation model by considering various hydrometeorological factors for ships with nonuniform movement. A real-time simulator was used for the numerical simulation of the container ship. To clarify the validity of the maneuvering mathematical model, sea trial results for the container ship were compared with the results for the present simulation system in terms of turn trajectory. In this study, a numerical technique based on Nomoto’s second-order model was employed to investigate the turning characteristics of a container ship. …

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Identifying Nonlinear Oscillators By An Energetic Functional In The Linear Space Of Temporal Boundary Functions, Chein-Shan Liu, Yung-Wei Chen, Jiang-Ren Chang Jun 2019

Identifying Nonlinear Oscillators By An Energetic Functional In The Linear Space Of Temporal Boundary Functions, Chein-Shan Liu, Yung-Wei Chen, Jiang-Ren Chang

Journal of Marine Science and Technology–Taiwan

We resolve the inverse problems of a second-order nonlinear oscillator to recover time-dependent damping function and nonlinear restoring force, with the help of temporal boundary data measured at initial time and final time. By using these data, a sequence of temporal boundary functions of time is derived, which satisfy the measured temporal boundary conditions automatically, and are at least the fourth-order polynomials of time. All the temporal boundary functions and zero element constitute a linear space, and a new concept of energetic functional is introduced in the linear space, of which the energy is preserved for each energetic temporal boundary …

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Experimental And Numerical Analysis Of The Drag Force On Surfboards With Different Shapes, Omar Lahlou May 2019

Experimental And Numerical Analysis Of The Drag Force On Surfboards With Different Shapes, Omar Lahlou

Theses and Dissertations

The aim of the present study is to define the hydrodynamic resistance of surfboards with different designs. Decreasing the drag acting on a board helps the surfer to attain higher surfing performances. It helps to attain higher speeds and maneuvering for the surfer. In this thesis, theoretical, experimental and computational approaches are used to explain how the drag changes with different surfboard shapes. Four surfboards with varying shapes were towed at different speeds and the resulting force was recorded. Two computational models were developed using Star CCM and Flowsquare to confirm the experimental results. The drag force on the boards …

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Membrane Hull Technology Implemented Into A D-Collar Work Boat, Joshua Hagan May 2019

Membrane Hull Technology Implemented Into A D-Collar Work Boat, Joshua Hagan

Theses and Dissertations

Membrane Hull Technology (MHT) was initially developed for the United States Navy Rigid-Hull Inflatable Boats (RHIB) as an alternative structure design to provide weight savings and shock mitigation. MHT accomplishes this by veering away from traditional hull design and utilizing a grid like system with an increased number of longitudinal stringers and transverse frames with a significantly lower moment of inertia when compared to traditional stringers and bulkheads. The decrease in stiffness allows for increased deflection in the hull during high load events with the added benefit of shock absorption. This technology, developed by Structural Composites Inc., has been successfully …

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Feasibility Study And Hydrodynamics Of Transformable Submersible Hydrofoil Trimaran, Yipeng Pan May 2019

Feasibility Study And Hydrodynamics Of Transformable Submersible Hydrofoil Trimaran, Yipeng Pan

Theses and Dissertations

It has been the endeavor of naval architects to design innovative hull forms to address the political, socio-economic climate and sustainability around the world. It is imperative that countries be able to protect their sea lanes and coastal zones from surveillance and infiltration from hostile foreign entities. Hence there is a need to develop radically different hull form, which possess the elusive ability and are capable of high-speed. In order to fulfill the idea, the hypothesis envisioned in this thesis is: the Transformable Submersible Hydrofoil Trimaran (TSHT) as an innovative and ground breaking hull form would address the feasibility of …

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Cavitation Number As A Function Of Disk Cavitator Radius: A Numerical Analysis Of Natural Supercavitation, Reid Prichard Apr 2019

Cavitation Number As A Function Of Disk Cavitator Radius: A Numerical Analysis Of Natural Supercavitation, Reid Prichard

Senior Honors Theses

Due to the greater viscosity and density of water compared to air, the maximum speed of underwater travel is severely limited compared to other methods of transportation. However, a technology called supercavitation – which uses a disk-shaped cavitator to envelop a vehicle in a bubble of steam – promises to greatly decrease skin friction drag. While a large cavitator enables the occurrence of supercavitation at low velocities, it adds substantial unnecessary drag at higher speeds. Based on CFD results, a relationship between cavitator diameter and cavitation number is developed, and it is substituted into an existing equation relating drag coefficient …

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