Investigation of Restoring Stiffness in the Hydroelastic Analysis of Slender Marine Structures

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
I. Senjanović ◽  
N. Hadžić ◽  
M. Tomić
Keyword(s):  
Relevant Literature ◽  
Flexible Structures ◽  
Practical Implementation ◽  
Marine Structures ◽  
Geometric Stiffness ◽  
Hydroelastic Analysis ◽  
Analytical Formulae ◽  
Hydroelastic Response ◽  
New Formula ◽  
Restoring Stiffness

The restoring stiffness, which couples displacements and deformations, plays a very important role in hydroelastic analysis of marine structures. The problem of its formulation is quite complex and is still discussed in relevant literature. In this paper, the recent formulations of restoring stiffness are correlated and analyzed. Due to some common terms of the restoring and geometric stiffness, the unified stiffness is established and compared with the complete restoring stiffness known in relevant literature. It is found out that the new formula deals with more terms and that under some assumptions, it is reduced to the known complete restoring stiffness. The unified stiffness constitution is analyzed through derived analytical formulae for prismatic pontoon. Its consistency is checked for the rigid body displacements. Also, numerical results of the hydroelastic response of segmented barge are correlated with available model test results. Some issues, that are important for practical implementation in the hydroelastic code for flexible structures, are described.

The Role of Compliance in the Design of MEMS

1996 ◽  
Author(s):  
G. K. Ananthasuresh ◽  
Sridhar Kota
Keyword(s):  
Mechanical Design ◽  
Relevant Literature ◽  
Flexible Structures ◽  
Mechanical Systems ◽  
Great Majority ◽  
Micro Electro Mechanical Systems

Abstract A great majority of the available micro devices and systems use compliant (or flexible) structures and mechanisms. This trend in design takes advantage of micromachining techniques while satisfying the constraints imposed by them. By citing relevant literature, this article briefly notes the influence of compliance on the mechanical design and analysis of Micro-Electro-Mechanical Systems (MEMS).

Global Hydroelastic Analysis of Pontoon-Type VLFS

2009 ◽  
Author(s):  
L. L. Jiao ◽  
M. Greco ◽  
O. M. Faltinsen
Keyword(s):  
Numerical Solutions ◽  
Parameter Analysis ◽  
Local Analysis ◽  
Two Dimensional ◽  
Numerical Wave Tank ◽  
Regular Waves ◽  
Hydroelastic Analysis ◽  
Air Cushion ◽  
Numerical Wave ◽  
Hydroelastic Response

A two-dimensional composite strategy given by Greco et al. [1] is applied to couple a linear global solution with a nonlinear local analysis. Globally a linear hydroelastic analysis is performed by an accurate Beam-On-Elastic-Foundation (BOEF) method. A parameter analysis of hydroelastic response of the structure is also carried out. Locally, a two-dimensional fully-nonlinear numerical wave tank (NWT) in combination with a Boundary Element Method (BEM) is developed to estimate the interaction between regular waves and the structure restrained from rigid and elastic motions. The effect of air cushion is considered. Present results are compared with experimental data and other numerical solutions.

Barriers of knowledge transfer and mitigating strategies in collaborative management system implementations

2019 ◽  
Vol 49 (1) ◽  
pp. 2-20 ◽  
Author(s):  
Juanqiong Gou ◽  
Nan Li ◽  
Tete Lyu ◽  
Xiyan Lyu ◽  
Zuopeng Zhang
Keyword(s):  
Information Systems ◽  
Knowledge Transfer ◽  
Management System ◽  
Transfer Problem ◽  
Relevant Literature ◽  
Implementation Process ◽  
Collaborative Management ◽  
Practical Implementation ◽  
Content Type ◽  
Implementation Methodology

PurposeAs the dynamics of the external environment of the enterprise continue to increase, the support of information systems for organizational agility becomes increasingly important. Collaborative Management System (CMS) is a new type of information system that can cope with the dynamic changes of the organization. Effective knowledge transfer is the core of the system implementation. The purpose of this study is to explore the knowledge transfer barriers faced by CMS in its implementation process.Design/methodology/approachThrough field interviews with a representative CMS provider, this paper summarizes the barriers of knowledge transfer during CMS implementation into three aspects.FindingsBased on the innovative measures taken by the company and relevant literature, the corresponding mitigating strategies are proposed.Originality/valueThe findings enrich the implementation methodology of agile information systems by exploring the knowledge transfer problem from a novel context. The study also provides a reference for practical implementation to overcome the dilemma of knowledge transfer.

Very Large Floating Structures

2007 ◽  
Author(s):  
H. Suzuki ◽  
H. R. Riggs ◽  
M. Fujikubo ◽  
T. A. Shugar ◽  
H. Seto ◽  
...  
Keyword(s):  
Design Procedure ◽  
Offshore Structures ◽  
Floating Structure ◽  
Floating Structures ◽  
Design Procedures ◽  
Novel Technology ◽  
Hydroelastic Analysis ◽  
Behavior Design ◽  
Hydroelastic Response ◽  
Near Future

Very Large Floating Structure (VLFS) is a unique concept of ocean structures primary because of their unprecedented length, displacement cost and associated hydroelastic response. International Ship and Offshore Structures Congress (ISSC) had paid attention to the emerging novel technology and launched Special Task Committee to investigate the state of the art in the technology. This paper summarizes the activities of the committee. A brief overview of VLFS is given first for readers new to the subject. History, application and uniqueness with regard to engineering implication are presented. The Mobile Offshore Base (MOB) and Mega-Float, which are typical VLFS projects that have been investigated in detail and are aimed to be realized in the near future, are introduced. Uniqueness of VLFS, such as differences in behavior of VLFS from conventional ships and offshore structures, are described. The engineering challenges associated with behavior, design procedure, environment, and the structural analysis of VLFS are introduced. A comparative study of hydroelastic analysis tools that were independently developed for MOB and Mega-Float is made in terms of accuracy of global behavior. The effect of structural modeling on the accuracy of stress analysis is also discussed. VLFS entails innovative design methods and procedure. Development of design criteria and design procedures are described and application of reliability-based approaches are documented and discussed.

Flexible Electrode Structures for Thermo-Tunneling Applications

2011 ◽  
Author(s):  
Eniko T. Enikov ◽  
Carlos Gamez ◽  
Shezaan Kanjiyani ◽  
Mahdi Ganji ◽  
Joshua Gill
Keyword(s):  
Magnetic Field ◽  
Contact Area ◽  
Numerical Solutions ◽  
Flexible Structures ◽  
Tunneling Current ◽  
Hot Electrons ◽  
Practical Implementation ◽  
Small Current ◽  
Thermo Electric ◽  
Asymmetric Mode

Combined thermionic emission and tunneling of hot electrons (thermo-tunneling) has emerged as a potential new solid-state cooling technology. Practical implementation of thermo-tunneling, however, requires the formation of a nanometer-sized gap spanning macroscopically significant surfaces. Thermo-tunneling of hot electrons across a few-nanometer gap has application to vacuum electronics, flat panel displays, and holds great potential in thermo-electric cooling and energy generation. Development of new thermo-tunneling applications requires creation of a stable nanometer gap between two surfaces. This presentation is focused on our effort to investigate the feasibility of creating such gaps using distributed electro-magnetic forces arising in thin-film flexible structures. Early efforts based on rigid electrodes showed that the effective tunneling approaches 400 square-micrometers, which albeit small, could lead to useful practical systems. In this presentation, we report a theoretical and experimental investigation of a thin-electrode system which could lead to further increase on the effective tunneling area. The device under study consists of a thin membrane collector electrode (anode) suspended over the emitting electrode (cathode). The structure is placed in a vacuum enclosure with an externally generated magnetic field perpendicular to the current flow in the membrane. The resulting Lorentz force is then directed upwards, separating the two surfaces. A mathematical model of the steady-state operation of the device is presented along with predictions of the contact area and tunneling current. Essential output parameters of the model include a central contact area measured by its length (delta) and the thermo-tunneling current. Both parameters are determined as a function of the externally applied external potential and magnetic field. Numerical solutions of the model show two possible operating modes: (1) symmetric deformation with negligibly small current; and (2) asymmetric mode where the B-field controls the current and contact area.

scholarly journals Synergizing climate change mitigation and adaptation in Cameroon

2019 ◽  
Vol 11 (1) ◽  
pp. 118-136 ◽  
Author(s):  
Faith Ngum ◽  
Dieudonne Alemagi ◽  
Lalisa Duguma ◽  
Peter A. Minang ◽  
Anderson Kehbila ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Change Mitigation ◽  
Policy Design ◽  
Relevant Literature ◽  
Technical Committee ◽  
Practical Implementation ◽  
Content Type ◽  
Mitigation And Adaptation ◽  
The Government ◽  
Change Mitigation

PurposeThis paper aims to examine the policy environments, institutional arrangements and practical implementation of some initiatives undertaken by the Government of Cameroon, together with some relevant stakeholders, in addressing climate change mitigation and adaptation at various levels in the country, which are prerequisites to promote synergistic ways of addressing climate change mitigation and adaptation.Design/methodology/approachUsing a qualitative approach to data collection, the paper draws upon information collected from relevant literature and interviews with 18 key country resource personnel.FindingsResults revealed that most reviewed policies/programs/strategies do not mention “climate change” explicitly but propose some activities which indirectly address it. Interaction is fair within the government ministries but weak between these ministries and other institutions. Inadequate financial resources are being opined as the most important challenge stakeholders are (and would continue) facing as a result of adopting integrated approaches to climate change. Other challenges include inadequate coordination, insufficient sensitization and capacity building, ineffective implementation, inadequate compliance, lack of proper transparency and inadequate public participation. To redress the aforementioned constraints and challenges, the paper concludes by outlining a number of recommendations for policy design.Originality/valueThe following recommendations were made: create a national technical committee to oversee and provide scientific guidance to the government on synergistic approaches; promote private sector investment and sponsorship on synergistic approaches; create local awareness, etc. It is important to underscore that minimal studies have been conducted to analyze multi-stakeholder perspectives on synergies between climate change mitigation and adaptation in Cameroon. This study attempts to bridge this major gap.

A Hybrid Empirical-Numerical Method for Hydroelastic Analysis of a Floater-and-Net System

2016 ◽  
Vol 60 (01) ◽  
pp. 14-29 ◽  
Author(s):  
Leixin Ma ◽  
Ke Hu ◽  
Shixiao Fu ◽  
Torgeir Moan ◽  
Runpei Li
Keyword(s):  
Hybrid Method ◽  
Hydrodynamic Force ◽  
Scale Effects ◽  
Fish Farming ◽  
Full Scale ◽  
Hydrodynamic Models ◽  
Load Models ◽  
Hydroelastic Analysis ◽  
Net Cages ◽  
Hydroelastic Response

Because of scale effects and inappropriate hydrodynamic models, the nonlinear hydroelastic response of net cages used for fish-farming cannot be analyzed precisely with traditional model testing or combinations of finite element methods (FEMs) and load models. In this study, an innovative hybrid method is proposed to determine the hydroelastic response of full-scale floater-and-net systems more accurately. In this method, the net for the fish cage was vertically and peripherally divided into similar interconnected sections with different hydrodynamic parameters, which were assumed to be uniformly distributed over each section. A model of a typical section was subjected to various towing velocities, oscillation periods, and amplitudes in a towing tank to simulate the potential motions of all sections in the net under various currents, waves, and floater movements. By analyzing the measured hydrodynamic force from this test section, a hydrodynamic force database for a typical net section under various currents, waves, and floater motions was built. Finally, based on an FEM, the modified Morison equation and the hydrodynamic force database, the hydroelastic behavior of the full-scale fish cage was calculated with an iterative scheme. It is demonstrated that this hybrid method is able to produce correct hydroelastic response for both steady and oscillatory flows. The hydroelastic response of a two-dimensional example of a full-length net panel with steady currents and floater oscillations was studied in detail.

scholarly journals New Formula for Geometric Stiffness Matrix Calculation

2016 ◽  
Vol 04 (04) ◽  
pp. 733-748 ◽  
Author(s):  
I. Němec ◽  
M. Trcala ◽  
I. Ševčík ◽  
H. Štekbauer
Keyword(s):  
Stiffness Matrix ◽  
Geometric Stiffness ◽  
New Formula ◽  
Matrix Calculation
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