scholarly journals An evolutionary optimization technique applied to resistance reduction of the ship hull form

2013 ◽  
Vol 10 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Hassan Zakerdoost ◽  
Hassan Ghassemi ◽  
Mahmoud Ghiasi
Keyword(s):  
Optimization Technique ◽  
Ship Hull ◽  
Point Of View ◽  
Computational Method ◽  
Hydrodynamic Performance ◽  
Optimization Process ◽  
Design Constraint ◽  
Hull Form ◽  
Performance Point ◽  
Wigley Hull

Hull form optimization from a hydrodynamic performance point of view is an important aspect of ship design. This paper presents a computational method to estimate the ship resistance (viscous & wave) in calm-water. In the optimization process the evolution strategy (ES) technique is linked to the computational method to obtain an optimum hull form by taking into account the displacement as design constraint. For allowing the large variation of hull form during optimization process the hull surface is represented by NURBS. New hull forms are obtained from the well-known S60 hull and the classical Wigley hull taken as initial hulls in the optimization process at Fn=0.316. The optimization variables are a combination of ship hull offsets and main dimensions. The benchmark results for two test cases indicate that the total resistance of optimized hulls is reduced significantly.DOI: http://dx.doi.org/10.3329/jname.v10i1.12927

Geometrical Variation and Distortion of Ship Hull Forms

2003 ◽  
Vol 40 (04) ◽  
pp. 239-248
Author(s):  
Ebru Narh ◽  
Kadir Sariöz
Keyword(s):  
Computer Aided Design ◽  
Ship Hull ◽  
Hydrodynamic Performance ◽  
Hull Form ◽  
Nonlinear Distortions ◽  
Form Design ◽  
Hull Form Design ◽  
Geometrical Variation ◽  
Hull Forms ◽  
Aided Design

Because of the risk involved with starting the hull form design from scratch, the designer most frequently initiates the hull form design process with a parent form that has satisfactory hydrodynamic performance. Hence, linear and nonlinear variation and distortion techniques have found wide applications in the hull form design studies. Some of these methods are simple and easy to apply by practicing naval architects, whereas others may be considered too complicated and difficult to use without simplifications. Existing and emerging techniques to distort a parent ship hull form are discussed and applied to a typical ship form. These techniques range from a simple one minus prismatic method to complex nonlinear distortions and include emerging computer-aided design (CAD) methods, such as shape averaging. The applications indicate that the techniques presented can be safely applied to conventional ship hull forms. The advantages and drawbacks of these methods are discussed, and numerical results are presented.

scholarly journals The Effect of Hull Form Parameters on the Hydrodynamic Performance of a Bulk Carrier

2021 ◽  
Vol 9 (4) ◽  
pp. 373
Author(s):  
Rui Deng ◽  
Shigang Wang ◽  
Yuxiao Hu ◽  
Yuquan Wang ◽  
Tiecheng Wu
Keyword(s):  
Optimization Method ◽  
Hydrodynamic Performance ◽  
Optimization Process ◽  
Joint Optimization ◽  
Empirical Methods ◽  
Bulk Carrier ◽  
Hull Form ◽  
Ship Resistance ◽  
Principal Dimension ◽  
Integrated Performance

In this study, the effect of joint optimization of the principal dimensions and hull form on the hydrodynamic performance of a bulk carrier was studied. In the first part of the joint optimization process, fast principal-dimension optimization of the origin parent ship considering the integrated performance of ship resistance, seakeeping, and maneuverability, as well as their relationships with the principal dimensions were analyzed in detail based on the ship resistance, seakeeping qualities, and maneuverability empirical methods of Holtrop and Mennen, Bales, and K and T indices, respectively. A new parent ship was chosen from 496 sets of hulls after comprehensive consideration. In the remaining part, a further hull form optimization was performed on the new parent ship according to the minimum wave-making resistance. The obtained results demonstrate that: (a) For the case in which the principal dimension of the original parent-type ship is different from that of the owner’s target ship, within the bounds of the relevant constraints from the owner, an excellent parent ship can be obtained by principal-dimension optimization; (b) the joint optimization method considering the principal dimension and hull form optimization can further explore the optimization space and provide a better hull.

scholarly journals Low Power Digital Multimedia Telecommunication Designs

VLSI Design ◽  
2001 ◽  
Vol 12 (3) ◽  
pp. 301-315 ◽  
Author(s):  
Koon-Shik Cho ◽  
Jun-Dong Cho
Keyword(s):  
Motion Estimation ◽  
Low Power ◽  
Communication Systems ◽  
Matched Filter ◽  
Optimization Technique ◽  
Low Power Design ◽  
Multimedia Systems ◽  
Wireless Multimedia ◽  
Design Constraint ◽  
Power Capability

The increasing prominence of wireless multimedia systems and the need to limit power capability in very-high density VLSI chips have led to rapid and innovative developments in low-power design. Power reduction has emerged as a significant design constraint in VLSI design. The need for wireless multimedia systems leads to much higher power consumption than traditional portable applications. This paper presents possible optimization technique to reduce the energy consumption for wireless multimedia communication systems. Four topics are presented in the wireless communication systems subsection which deal with architectures such as PN acquisition, parallel correlator, matched filter and channel coding. Two topics include the IDCT and motion estimation in multimedia application.These topics consider algorithms and architectures for low power design such as using hybrid architecture in PN acquisition, analyzing the algorithm and optimizing the sample storage in parallel correlator, using complex matched filter that analog operational circuits controlled by digital signals, adopting bit serial arithmetic for the ACS operation in viterbi decoder, using CRC to adaptively terminate the SOVA iteration in turbo decoder, using codesign in RS codec, disabling the processing elements as soon as the distortion values become great than the minimum distortion value in motion estimation, and exploiting the relative occurrence of zero-valued DCT coefficient in IDCT.

An Integrated Ship Re-Design/Modification Strategy

2019 ◽  
Vol 161 (A1) ◽  
Keyword(s):  
Computer Aided Design ◽  
Modular Design ◽  
Ship Hull ◽  
Cfd Model ◽  
Hull Form ◽  
Design Modification ◽  
Technical Parameters ◽  
Computational Fluid Dynamics Cfd ◽  
Bulbous Bow ◽  
Aided Design

Herein, we present an integrated ship re-design/modification strategy that integrates the ‘Computer-Aided Design (CAD)’ and ‘Computational Fluid Dynamics (CFD)’ to modify the ship hull form for better performance in resistance. We assume a modular design and the ship hull form modification focuses on the forward module (e.g. bulbous bow) and aft module (e.g. stern bulb) only. The ship hull form CAD model is implemented with NAPA*TM and CFD model is implemented with Shipflow**TM. The basic ship hull form parameters are not changed and the modifications in some of the technical parameters because of re-designed bulbous bow and stern bulb are kept at very minimum. The bulbous bow is re-designed by extending an earlier method (Sharma and Sha (2005b)) and stern bulb parameters for re-design are computed from the experience gained from literature survey. The re-designed hull form is modeled in CAD and is integrated and analyzed with Shipflow**TM. The CAD and CFD integrated model is validated and verified with the ITTC approved recommendations and guidelines. The proposed numerical methodology is implemented on the ship hull form modification of a benchmark ship, i.e. KRISO container ship (KCS). The presented results show that the modified ship hull form of KCS - with only bow and stern modifications - using the present strategy, results into resistance and propulsive improvement.

New Promising Generation of Twin-Gondola LNG Carriers Optimized with the Aid of CFD Calculations

2005 ◽  
Author(s):  
Henk V. Valkhof ◽  
Eduardo Minguito ◽  
Klaas Kooiker
Keyword(s):  
Viscous Flow ◽  
Far East ◽  
Point Of View ◽  
Maximum Efficiency ◽  
Hull Form ◽  
Overall Design ◽  
Computational Fluid Dynamics Cfd ◽  
New Generation ◽  
Hydrodynamic Optimization ◽  
Adequate Design

As natural gas is becoming an important energy source, a large fleet is needed to transport it in liquefied form across the oceans in specially designed LNG carriers from mainly the Middle East towards the Far East. During the overall design process of such a vessel the shape of the hull form and its propulsors play an important role from a hydrodynamic point of view. This paper describes the design of a twin-gondola LNG carrier for Navantia. The twingondola aft body has proven to be an adequate design concept, but due to the complexity of the flow around the aft body the design should be carried out with great care. Computational Fluid Dynamics (CFD) tools are extremely valuable in the hydrodynamic optimization process of the hull. In this design both potential flow codes and viscous flow codes have been used to obtain the optimum hull form. With the results of the PARNASSOS viscous flow calculations it was possible to make decisions with regard to the horizontal angle and the inclination of the gondolas, and the slope of the buttocks in the area between the gondolas. Special attention has been paid to avoid flow separation around the aft body. The gondolas have been oriented in such a way that maximum efficiency is achieved. The performance of the resulting design has been verified by model tests in MARIN’s Deep Water Towing Tank. Given the very promising results of this new generation of LNG carriers, achieving besides the excellent propulsive properties also a higher payload target, the yard became more competitive and is expecting quite some orders for this particular ship type.

The Potential of The Hotel Industry In Pandemic Era Based On Finance Performance Point Of View, Case Study: Indonesia

2021 ◽  
Vol 1 (1) ◽  
pp. 111-123
Author(s):  
Anton Effendi ◽  
◽  
Bambang Hadi Prabowo
Keyword(s):  
Hospitality Industry ◽  
Stock Exchange ◽  
Hotel Industry ◽  
Secondary Data ◽  
Reliable Data ◽  
Point Of View ◽  
Threshold Autoregressive ◽  
Performance Point ◽  
Occupancy Rates

This article aims to investigate and analyze the potential of the hospitality industry by comparing the potential occupancy rates and hotel revenues of foreign and domestic tourists. This investigation uses an investigation of company data obtained from reports from hotel companies throughout Indonesia which are listed on the Indonesia Stock Exchange and secondary data obtained from world banks and other reliable data. This study uses behavioral data analysis using Threshold Autoregressive from 2000 to 2019. It was found that domestic tourists are a new hope that needs to be considered in surviving and restoring the hospitality industry after being exposed to the COVID-19 pandemic which has led hotel companies. temporarily closed operations and part of the hotel went bankrupt. Optimization of domestic tourists allowed the hotel industry to develop rapidly after the Covid-19 pandemic ended.

Optimization Design of an Axial-Flow Fan Used in Local Ventilation in Mining Industry

2011 ◽  
Author(s):  
Dhaval Desai ◽  
Jiang Zhou
Keyword(s):  
Optimization Design ◽  
Optimization Technique ◽  
Mining Industry ◽  
Axial Flow ◽  
Optimization Method ◽  
Low Noise ◽  
Design Constraint ◽  
Engineering Research ◽  
Blade Element Theory ◽  
Local Ventilation

In a world where the increasing demand on developing energy-efficient systems is probably the most stringent design constraint, the trend in engineering research in recent years has been to optimize the existing technologies rather than to implement new ones. The present work addresses a robust axial-type fan design technique developed using an optimization technique. A fan is indispensable equipment for primary and local ventilation in mining industries. We always pursue the fan with high working efficiency and low noise. In this paper, an optimization method is developed to improve the pneumatic properties of the fan based on the blade element theory. A new type of fan used in local ventilation is designed with the help of computer. It is shown that the new design enhanced the efficient up to 88%. Numerical analysis is also conducted to validate the optimization design results.

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