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Dynamic Dynamic Analysis of Articulated Floating Bridges
A. Srinivas, C.P. Vendhan and S.K. Bhattacharyya

Study of Problem of Exhaust Smoke Ingress into GT Intakes of a Naval Ship
V Seshadri, SN Singh, Cdr PR Kulkarni

Submarines in New World Order - The 21st Century Challenge
Pär Dahlander, Peter Hauschildt

Three Dimensional Wave Forces of First and Second Order on Large Cylinders
Mohammed Jameel, Suhail Ahmad

Effective Feed Back for Better Ship Design
Cdr Saibal Sen, Cdr Manohar Kapale

Wave Propagation Across Junctions Between Rigid and Porous Panels in Boundary Layer Flow on a Flat Plate
S. Hegde, P. K. Sen, P. W. Carpenter and A. R. Paul

Nanotechnology - A Revolution in its Infancy for Paint
Lt Cdr Amit Kapoor and A.S. Khanna

Ship Recycling Activities In India- An Overview
K Sivaprasad

BACK COVER, Vol. 2, No. 1, Jan 2006

Dynamic Dynamic Analysis of Articulated Floating Bridges
A. Srinivas, C.P. Vendhan and S.K. Bhattacharyya
 
ABSTRACT
This paper presents a study on the dynamics of an articulated floating bridge design concept, called Amphibious Floating Bridge Ferry System (AFFS) which consists of a central hull (main hull) with two secondary hulls (inner ramps) hinged on either end, together with approach ramps (outer ramps). Single or multiple units of AFFS can serve as a bridge across waterways. Numerical modeling of its ‘bridge mode’ dynamic behaviour under moving loads has been carried out using the linear finite element method. The mode superposition method is employed for forced response calculations by treating the problem as a moving force problem, ignoring the moving mass effects. The modal equations are solved in the time domain. The efficacy of the static correction technique in improving the modal summation, especially of the bending moments, has
been investigated. The AFFS hull structure has been idealized using beam elements. Stiffness due to buoyancy support in flexural mode and added mass effect have been included in the formulation. Joint flexibility at the articulated connections between the various hull and ramp elements has been considered. A numerical study of modal analysis has been carried out on different AFFS configurations, viz, one-, two- and ten-unit systems. Moving load analysis has been carried out under a single as well as multiple moving point loads. The dynamic magnification factors for the AFFS problem are very close to unity, and in a few cases the factors fall below unity. Buoyancy has significant effect on the response of simply supported AFFS. For the ten-unit AFFS, as the load moves, the mid-span is seen to experience hogging (or negative) bending moments also, whereas the peak bending moments are sagging in nature. Structural damping reduces the peak responses only slightly.
 
Keywords:
Amphibious Floating Bridge Ferry System (AFFS), Floating bridge, Moving loads, Finite element analysis, Mode superposition, Static correction, Dynamic magnification.
 
 
Study of Problem of Exhaust Smoke Ingress into GT Intakes of a Naval Ship
 V Seshadri, SN Singh, Cdr PR Kulkarni
 
ABSTRACT
The rise in the intake air temperature of the gas turbines has been reported in some of the newly designed ships. This not only adversely affects the efficiency of the gas turbines but can also affect their life and reliability. Solving the smoke nuisance problem on the already constructed and operational ships with dubious exhaust emission performance involves investigation by wind tunnel studies, which play an important role in recommending modifications to the topside configuration and in the imperative troubleshooting between the launch and delivery of such a vessel. The paper presents an investigation of the phenomenon on a naval ship wherein the problem was detected after the launch of the ship, during the sea acceptance trials. The trials team reported unexplained high ambient air temperature at GT intake. Investigation of the problem at IIT Delhi by simulating the phenomenon in a Wind Tunnel found that the exhaust
smoke exiting from the funnel was being sucked into the GT intake. On the basis of results from the experiments, several modifications were suggested in the geometry of funnel and GT intakes as well as the topside configuration to overcome the problem. The study presents the recommendations for modification to the topside configuration on the vessel to overcome the undesirable problem of ingress of the exhaust smoke into the GT intake and highlights the need to detect such shortfalls in design very early in the design spiral and to find efficient means to eliminate them so as to avoid the costly post construction additions and alterations.
 
Keywords :
Exhaust Smoke, GT Intake, Topside, Ship Aerodynamics
 
Submarines in New World Order – The 21st Century Challenge
Pär Dahlander, Peter Hauschildt
 
ABSTRACT
The submarine was first conceived and developed as a first rate war fighter in high intensity combat operations. The New World Order, however, calls for the submarine to have a broader spectrum of capabilities in order to remain relevant in the emerging security environment. By using new technological solutions in real time communication, Unmanned Underwater Vehicles, propulsion, and weapons this can be achieved. Furthermore, using modular design a submarine can become a flexible platform that can be specifically tailored for a wide range of missions across the operational spectrum. With the appropriate technology the submarine is sure to remain a premier warship for the foreseeable future.
 
Keywords:
Submarine Design, New World Order, Flexible payload, Network Centric Operations, AIP, MOOTW (Military Operations Other Than War).
 
Three Dimensional Wave Forces of First and Second Order on Large Cylinders
Mohammed Jameel, Suhail Ahmad
 
ABSTRACT
The evaluation of wave forces on vertical surface of piercing cylinder has been a subject of interest, as the cylindrical members are often used as components of many marine structures. When the diameter of such components is comparatively large with respect to the incident wave length, it changes the wave field in the vicinity. The total wave force on such a structure is given by the sum of first and second order wave forces. In many applications, it is the second order wave forces on a body that are of interest. The scattering of waves introduces several important constraints which may cause failure, if they are not taken into account. The computation of second order wave forces on a three dimensional large cylinder is quite complex. In the last two decades, several analytical methods have been proposed by different investigators. In the present
study, the analytical formulation for first and second order wave forces on large cylinder, as proposed by Taylor and Hung [1], has been considered. This method has wide range of applicability and relatively easy convergence of free surface integral. An algorithm based on this approach has been developed. This algorithm is then coded for the computer software for evaluation of forces due to regular waves in the finite and infinite depths of water. Results for both finite and infinite water depths have been obtained for regular wave. A Spar cylinder (Spar platform, used for exploration of Oil, Natural Gas and harnessing Ocean thermal energy from deep sea) has been chosen from the literature. The results show the relative importance and contribution of various force components of first and second order on spar cylinder.
 
Keywords:
Wave diffraction, hydrodynamic forces, second order waves, Spar
 
Effective Feed Back for Better Ship Design
Cdr Saibal Sen, Cdr Manohar Kapale
 
ABSTRACT
Ship design and shipbuilding are ever changing technological fields. One of the major changes in design has been removal of the traditional long drawing board for drafting ship lines and adoption of the small screen for all design work. While the computers have reduced the chances of errors in design and its transformation into a ship, the agencies involved in subsequent exploitation of the platform still report back an alarmingly high number of design deficiencies. Appropriate action on these reports to eradicate the deficiency leads to valuable improvements in design. This paper proposes a model to collect, collate and analyse design deficiencies reported and improvements by the users and other agencies like overseers, surveyors, trial agencies, maintainers and last but not the least, the owners. The feedback from these agencies needs a new method of analysis to arrive at the crux of the issue and then decide on a means to incorporate it into the design spiral at the appropriate place. This process continues right through the construction and trials of a design platform. While the information generated from this analysis is significant for the “follow-on” ships, it is also relevant to a new design project which may be entirely different in its role from the ship for which the feedback is received. The model keeps the designer at the centre of the design improvement and also proposes a method to institutionalize the feedback into any new design project.
 
Keywords:
Feed Back, Ship Design.
 
Wave Propagation Across Junctions Between Rigid and Porous Panels in Boundary Layer Flow on a Flat Plate
S. Hegde, P. K. Sen, P. W. Carpenter and A. R. Paul
 
ABSTRACT
The simulation of two dimensional small amplitude disturbance waves propagating over the junction of rigid-porous panels for the flat plate boundary layer flow is discussed here. Davies and Carpenter [1] have observed that there is a jump in the amplitude of the wave due to the sudden change in properties across the junction formed between two dissimilar panels. Sen et al. [2] formulated a wave driver theory to calculate the jump at the junction formed between rigid and compliant panels. In the present case of rigid-porous wall arrangement also, because of the normal velocity component on the porous side, there is a sudden change in properties across the rigidporous junction, which leads to a jump at the junction. Therefore the wave driver theory of Sen et al. [2] is applicable to the present problem of alternate rigid-porous panels, and this is the  ubject of investigation in the present work. Also, the distance from the junction over which the Blasius velocity profile is transformed to the asymptotic suction profile is investigated herein. Present numerical results are in good agreement with the work of Fransson [3].
 
Keywords:
Disturbance waves, Rigid-porous panels, Wave driver theory.
 
Nanotechnology – A Revolution in its Infancy for Paint
Lt Cdr Amit Kapoor and A.S. Khanna
 
ABSTRACT
Nanoparticles, represent a scale of matter where radically different phenomena manifest and dominate their behaviour. The field of nanostructure science and technology is a broad and interdisciplinary area of worldwide research. The research and development activity that has been going on in the past few years will certainly have a great impact in the future. Significant work on nanoscale coatings is underway worldwide in the areas of ceramics, cosmetics, biosensors, colorants, corrosion resistance and abrasion-resistant polymers. All these applications deal with incorporating nanoparticles that enhance specific features. Ability to manufacture smaller functional systems enhances performance, cost, and efficiency. These considerations power the drive towards miniaturization and precision finishing. There are a plethora of areas of opportunity, challenges, apprehensions and problems that lie ahead for advancement in nanotechnology with respect to coatings. Many studies are going on world over to establish the vast potential nanoparticles can unleash in the field of coatings. The paper presents an overview on Nanotechnology in coatings, its effect on the performance of paints and potential applications in terms of functional and smart coatings.
Ship Recycling Activities In India- An Overview
K Sivaprasad
 
ABSTRACT
India has approximately 30% share of global ship recycling market. With a long shipbuilding tradition, India is once again appearing in the forefront of marine business, but this time in the field of ship recycling and associated activities. Cheap labor costs and suitable coastline characteristics for ship breaking activities are the main reasons behind the emergence of this marine business in the country. High demand for second hand or pre-owned machinery, steel and outfitting items are a supporting factor for the success behind such recycling oriented industry. However, poor law enforcement and lack of proper eco-literacy are the flipside of the coin. The western state of Gujarat, North of Mumbai, has opened up its facilities in a big way for the ship recycling industry, which has become synonymous with the Alang ship-breaking yard. Interestingly India’s eastern coast is yet to get a break-through, although conditions are favorable. Vast potential exists in this emerging area, though the existing utilization is done in a haphazard manner. Ship recycling activity in India is in the spotlight currently in connection with the asbestos laden French aircraft carrier Clemenceau heading towards Indian waters for disposal. Environmentalists are keenly watching the developments and the judicial bodies are also intervening in the matter. This paper gives an overview of ship recycling activities at Alang shipyard (Bhavnagar District of Gujarat), where about 45,000 workers live and work in hazardous conditions.
 
Keywords:
Ship breaking, Ship Recycling, Alang
 
Copy of this volume can be purchased from the publishing office of the journal.