The concepts “science” and “religion” are both products of modernity. “Religion” took on its present meaning in the seventeenth century, “science,” during the nineteenth. An understanding of the social and historical processes which... more
The concepts “science” and “religion” are both products of modernity. “Religion” took on its present meaning in the seventeenth century, “science,” during the nineteenth. An understanding of the social and historical processes which have led to the formation of the dual categories “science” and “religion” is vital for any assessment of their current relationship. In each instance, the formation of the category came about through a process of reification which shifted the focus of attention away from the relevant human activities to abstract bodies of knowledge or sets of propositions. This has led to a distorted understanding of the phenomena which these terms purport to represent, a distortion which is magnified in discussions of their putative relationship. The constructed nature of the science-religion relation suggests the need for revision of standard approaches to the science and religion question.
"A study into the adoption of social media and web technologies in organisations and communities. The findings dispel the myth of the Generation Y dominance on social media, and reveal that the barriers to adoption include individual... more
"A study into the adoption of social media and web technologies in organisations and communities. The findings dispel the myth of the Generation Y dominance on social media, and reveal that the barriers to adoption include individual perceptions and boundaries toward new technologies, incorrect assumptions of prior learning and the need to change leadership styles when utilising social media. The scope of the research and its longitudinal nature make the study original.
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Measurements of the inertia parameters of a keelboat hull using a bifilar suspension are described. Bifilar yaw moment measurement normally entails accurate measurement of the length l and spacing 2d of the suspension, and of Ty the... more
Measurements of the inertia parameters of a keelboat hull using a bifilar suspension are described. Bifilar yaw moment measurement normally entails accurate measurement of the length l and spacing 2d of the suspension, and of Ty the period of pure yaw oscillation. The primary difficulty with a bifilar suspension is avoiding unwanted modes of oscillation, specifically sway when measuring yaw. However, for an athwartships suspension the sway motion is that of a simple pendulum of period Ts and observation of the combined motion allows the yaw gyradius to be determined as ky = (Ty/Ts)d. Thus only the ratio of the periods and the suspension spacing need be measured.
Measurements of the normal mode periods of the double pendulum motion when the hull is displaced in surge allows the pitch gyradius and the height of the center of mass to be determined.
Repeating yaw measurements with the hull tilted, and then with the bifilar suspension fore and aft allows all the elements of the inertia tensor of a symmetrical hull to be measured.
The powering issue of a high-speed marine vehicle with multihulls and air-cushion support is addressed, since there is an often need to quickly evaluate the effects of several configuration parameters in the early stage of the design. For... more
The powering issue of a high-speed marine vehicle with multihulls and air-cushion support is addressed, since there is an often need to quickly evaluate the effects of several configuration parameters in the early stage of the design. For component hulls with given geometry, the parameters considered include the relative locations of individual hulls and the relative volumetric ratios. Within the realm of linearized theory, an interference-resistance expression for hull-to-hull interaction is first reviewed, and then a new formula for hull-and-pressure distribution interference is derived. Each of these analytical expressions is expressed in terms of the Fourier signatures or Kochin functions of the interacting component hulls, with the separation, stagger, and speed as explicit parameters. Based on this framework, an example is given for assessing the powering performance of a catamaran (dihull) as opposed to a tetrahull system. Also examined is the wave resistance of a surface-eff...
This paper describes the process of constructing a fair, open or closed C1 surface over a given irregular curve mesh. The input to the surface construction consists of point and/or curve data which are individually marked to be... more
This paper describes the process of constructing a fair, open or closed C1 surface over a given irregular curve mesh. The input to the surface construction consists of point and/or curve data which are individually marked to be interpolated or approximated and are arranged according to an arbitrary irregular curve mesh topology (Fig. 1). The surface constructed from these data will minimize flexibly chosen fairness criteria. The set of available fairness criteria is able to measure surface characteristics related to curvature, variation of curvature, and higher order surface derivatives based on integral functionals of quadratic form derived from the second, third and higher order parametric derivatives of the surface. The choice is based on the desired shape character. The construction of the surface begins with a midpoint refinement decomposition of the irregular mesh into aggregates of patch complexes in which the only remaining type of building block is the quadrilateral Be´zier...
Abstract Flow field around different modern benchmark ship hull with self propulsion characteristics at varying longitudinal positions of rudder is computed using Computation Fluid Dynamics (CFD) technique. Numerical study is performed... more
Abstract Flow field around different modern benchmark ship hull with self propulsion characteristics at varying longitudinal positions of rudder is computed using Computation Fluid Dynamics (CFD) technique. Numerical study is performed around bare hull first to determine free surface wave elevation and resistance components. Zonal approach is applied to incorporate ‘potential flow solver’ in the region outside the boundary layer & wake, ‘boundary layer solver’ in thin boundary layer region near the hull and ‘Navier Stokes solver’ in the wake region successively. Lifting Line method coupled with RANS solver is used to compute propeller open and self propulsion characteristics at different positions of rudder. Verification and validation studies for resistance coefficients have also been carried out using ITTC recommended procedure. The present computational method reveals that CFD results of flow field around ship hull with propeller and rudder effects are prospective and can be successfully applied in maritime industry.
Computer Aided Geometric Design (CAGD) of surfaces sometimes presents problems that were not envisioned in classical differential geometry. This paper presents mathematical results that pertain to the design of curvature continuous... more
Computer Aided Geometric Design (CAGD) of surfaces sometimes presents problems that were not envisioned in classical differential geometry. This paper presents mathematical results that pertain to the design of curvature continuous blending surfaces. Curvature continuity across normal continuous surface patches requires that normal curvatures agree along all tangent directions at all points of the common boundary of two patches, called the linkage curve. The Linkage Curve theorem proved here shows that, for the blend to be curvature continuous when it is already normal continuous, it is sufficient that normal curvatures agree in one direction other than the tangent to a first order continuous linkage curve. This result is significant for it substantiates earlier works in computer aided geometric design. It also offers simple practical means of generating second order blends for it reduces the dimensionality of the problem to that of curve fairing, and is well adapted to a formulation of the blend surface using sweeps. From a theoretical viewpoint, it is remarkable that one can generate second order smooth blends with the assumption that the linkage curve is only first order smooth. The geometric criteria presented my be helpful to the designer since curvature continuity is a technical requirement in hull or cam design problems. The usefulness of the linkage curve theorem is illustrated with a second order blending problem whose implementation will not be detailed here.
This study comparation of hull form performance was analysed becaused there was suggestion that a ship was built by hull form scheming this time (Scheltema, Formdata, NPL Series) is better than a ship that was built traditionally because... more
This study comparation of hull form performance was analysed becaused there was suggestion that a ship was built by hull form scheming this time (Scheltema, Formdata, NPL Series) is better than a ship that was built traditionally because there is no basic erudite calculation in hull form design. So hull form design was result of natural adaptation. Such performance are ship’s resistance, stability, and ship’s navigation.This research about hull form performance is expected can give information about hull form performance using Scheltema method and can be one of alternative to hull form of fishing vessel design development to the modern design.The result based on the calculation and analysis, show that at a ship speed 9 knot, Scheltema method hull form can reduce wave resistance equal to 29,54% than Batang’s hull form. Meanwhile from stability facet, various condition shows that Batang’s hull form was better than Scheltema method. Meanwhile at wave spectrum 45°, rolling movement of B...
Computer Aided Geometric Design (CAGD) of surfaces sometimes presents problems that were not envisioned in classical differential geometry. This paper presents mathematical results that pertain to the design of curvature continuous... more
Computer Aided Geometric Design (CAGD) of surfaces sometimes presents problems that were not envisioned in classical differential geometry. This paper presents mathematical results that pertain to the design of curvature continuous blending surfaces. Curvature continuity across normal continuous surface patches requires that normal curvatures agree along all tangent directions at all points of the common boundary of two patches, called the linkage curve. The Linkage Curve theorem proved here shows that, for the blend to be curvature continuous when it is already normal continuous, it is sufficient that normal curvatures agree in one direction other than the tangent to a first order continuous linkage curve. This result is significant for it substantiates earlier works in computer aided geometric design. It also offers simple practical means of generating second order blends for it reduces the dimensionality of the problem to that of curve fairing, and is well adapted to a formulatio...
Edge detection is one of the most important techniques in image processing. In spite of 20 years of research, the need for general edge detector is still felt. The key uncertainty in the edge detection algorithm is Threshold decision. To... more
Edge detection is one of the most important techniques in image processing. In spite of 20 years of research, the need for general edge detector is still felt. The key uncertainty in the edge detection algorithm is Threshold decision. To deal with uncertainty of information, soft computing approach is a good mathematical framework. In this work, we used fuzzy logic for Automatic Thresholding and generated threshold is used with different methods for edge detection. The results obtained from the proposed method are found to be comparable to those from many well known edge detector. However, the values of the input parameters providing the appreciable results in the proposed detector.
This paper investigates the use of inertial actuators to reduce the sound radiated by a submarine hull under excitation from the propeller. The axial forces from the propeller are tonal at the blade passing frequency. The hull is modeled... more
This paper investigates the use of inertial actuators to reduce the sound radiated by a submarine hull under excitation from the propeller. The axial forces from the propeller are tonal at the blade passing frequency. The hull is modeled as a fluid-loaded cylindrical shell with ring stiffeners and equally spaced bulkheads. The cylinder is closed at each end by circular plates and conical end caps. The forces from the propeller are transmitted to the hull by a rigid foundation connected to the propeller shaft. Inertial actuators are used as the structural control inputs. The actuators are arranged in circumferential arrays and attached to the internal end plates of the hull. Two active control techniques corresponding to active vibration control and discrete structural acoustic sensing are implemented to attenuate the structural and acoustic responses of the submarine. In the latter technique, error information on the radiated sound fields is provided by a discrete structural acousti...
A passive isolation approach to reduce the sound pressure radiated by a submarine is presented. The submerged vessel is modeled as a stiffened cylindrical hull partitioned by bulkheads and with two end caps of conical shape. Fluctuating... more
A passive isolation approach to reduce the sound pressure radiated by a submarine is presented. The submerged vessel is modeled as a stiffened cylindrical hull partitioned by bulkheads and with two end caps of conical shape. Fluctuating forces from the propeller are transmitted to the hull through the shaft and a rigid foundation, resulting in axisymmetric excitation of the hull. The hull surface motion is mainly in the axial direction with a small radial component due to the coupling between the two orthogonal shell displacements. The sound pressure resulting from the axial motion is radiated from the end caps of the submarine. This work investigates reduction of the far field sound pressure by passive isolation of the end caps from the main hull. Isolation of the axial motion of the end caps from the cylindrical hull results in significant reduction of the radiated sound at low frequencies. The fluid loading approximation for a finite cylindrical shell in the low frequency range i...
Compilers of biographical dictionaries of early English women authors, and of anthologies of their writings, have a hard and repetitious time in their coverage of the late Middle Ages. There seems little to say, and most of it has been... more
Compilers of biographical dictionaries of early English women authors, and of anthologies of their writings, have a hard and repetitious time in their coverage of the late Middle Ages. There seems little to say, and most of it has been said already. The temptation to swell the female canon by perpetrating literary hoaxes, and to resurrect supposedly lost œuvres ; has been powerful; the acclaim enjoyed by the French poems attributed to the mythical Clothilde de Surville, published by a cunning bibliophile in the eighteenth century and reprinted until as recently as the 1950s, stands as an example. But more necessary than the traditional literary-historical task of amalgamating the scattered textual remains left by female authors is some investigation of the different senses in which ‘writing women’ might have existed in the period, especially in relation to texts such as lyrics, often narrated in the female voice, whose authorship is so notoriously hard to identify. This essay accordingly focuses on some questions concerning this area of definition, and explores the possibility of isolating distinctive features of female literary composition in the centuries which immediately preceded the profound cultural changes brought about by the shift from manuscript to print culture. What kinds and standards of literacy did medieval women possess? By what methods were the compositions of women ‘authors’ recorded and disseminated, in an age when scribal skills were not automatically concomitant with authorial ones? How is it possible to locate women's writing in a period characterised by anonymity? Only by uncovering exactly what constituted women's writing can we begin to answer the most pressing questions of feminist criticism: ‘what does writing as a woman mean, and to what extent does it involve a new theory and a new practice?
This study was aimed at knowing the effect of redesigned hull line of small purse-seiner on the vessel stability. Data inputs and simulation employed Maxsurf modeller Advanced and Maxsurf Stability Enterprice applications. Results showed... more
This study was aimed at knowing the effect of redesigned hull line of small purse-seiner on the vessel stability. Data inputs and simulation employed Maxsurf modeller Advanced and Maxsurf Stability Enterprice applications. Results showed different stability value of the vessel with new hull line from the prototype one that also met the standard stability of International Maritime Organization (IMO). Moreover, increase in vessel stability value occurred in the redesigned hull line of PKU-4 compared with that of the prototype vessel, PKU-1, and the redesigned vessel hull line of PKU-2 and PKU3. This finding confirms that the hull line of Manado prototype purse seiner could be improved in order to have better stability. Keyword: static stability, dynamic stability, vessel, purse seine. ————————————————————
The hydrodynamics performance of submerged and surface-piercing lifting bodies is analyzed by a potential flow model based on a Vortex Lattice Method (VLM). Such a numerical scheme, widely applied in aerodynamics, is particularly suitable... more
The hydrodynamics performance of submerged and surface-piercing lifting bodies is analyzed by a potential flow model based on a Vortex Lattice Method (VLM). Such a numerical scheme, widely applied in aerodynamics, is particularly suitable to model the lifting effects thanks to the vortex distribution used to discretize the boundaries of the lifting bodies. The method has been developed with specific boundary conditions to account for the development of steady free surface wave patterns. Both submerged bodies, such as flat plates and hydrofoils, as well as planing hulls can be studied. The method is validated by comparison against available experimental data and other Computational Fluid Dynamic (CFD) results from Reynolds Averaged Navier Stokes (RANS) approaches. In all the analyzed cases, namely 2D and 3D flat plates, a NACA hydrofoil, planning flat plates and prismatic planing hulls, results have been found to be consistent with those taken as reference. The obtained hydrodynamic ...
Conversion of very (ultra) large crude oil carriers (VLCC,ULCC) into floating production, storage and offloading (FPSO) offshore units has become a common practice in the industry. The conversion planning is complex and demands a careful... more
Submarine hulls are pressure vessels for which excellent structural integrity under underwater pressure loads is essential. The use of light-weight materials contributes to reduced fuel consumption, improved speed, and increased payload... more
Submarine hulls are pressure vessels for which excellent structural integrity under underwater pressure loads is essential. The use of light-weight materials contributes to reduced fuel consumption, improved speed, and increased payload while strength properties are retained. The focus of this paper is on the collapse behavior of a filament-wound cylindrical structure that serves as the main hull of a submarine subject to hydrostatic pressure loads. This paper presents a computational modelling approach for the prediction of the collapse behavior mechanism using a commercial finite element (FE) solver. The collapse strength obtained from the numerical model corresponded closely to available experimental data. The composite and aluminum material models were compared and the effects of stacking angle and thickness portion in the ply sequence on collapse strength were investigated. The advantages and disadvantages of available design codes (i.e., American Society of Mechanical Engineer...
Nowadays consumers are looking for new food products with added nutritional value. Therefore, producers and scientists develop new recipes and technologies with the aim to enrich products with fibres, vitamins, and probiotics. Since naked... more
Nowadays consumers are looking for new food products with added nutritional value. Therefore, producers and scientists develop new recipes and technologies with the aim to enrich products with fibres, vitamins, and probiotics. Since naked barley contains high concentration of soluble dietary fibre, including β-glucans, which have stabilising properties, it has a good potential for fermented dairy food development. The goal of the current study was to assess the application of hull-less barley grain ‘Kornelija’ for development of fibre-enriched yogurt. Milk was fermented with freeze-dried starter (Lactobacillus delbrueckii ssp. bulgaricus, Streptococcus thermophilus) by adding flour of ungerminated, 24 and 36 hours germinated barley grain (amount 2%, 3%, 4%) at 41 ± 1 oC up to pH 4.7 ± 1.0. pH of samples during fermentation, the colony forming units of lactic acid bacteria, viscosity, and concentration of fibres were determined. Results of the current study showed that flour from ung...
With the increasing demand for faster and lighter ferries the need for predicting motions and sea loads for efficient structural design and safe operation has become necessary. Operation at speeds of around 40 knots in the open ocean,... more
With the increasing demand for faster and lighter ferries the need for predicting motions and sea loads for efficient structural design and safe operation has become necessary. Operation at speeds of around 40 knots in the open ocean, where water impacts can result in structural damage and crew injuries emphasises the need for the development of reliable tools to accurately predict slam loads. This work investigated the behaviour of a quasi-2D section model of wave-piercing catamaran fitted with a centrebow during the impact phase using finite-volume Computational Fluid Dynamics (CFD), overlapping grids, Reynolds-Averaged Navier-Stokes (RANS) equations and Volume of Fluid (VOF) method to solve the water-entry problem. The computed vertical acceleration and slamming pressures are compared to previously published drop test experimental data and show good agreement. It was found that taking into account the compressibility of the trapped air is necessary to accurately predict slamming ...
Abstract: This paper contains a description of the mechanical design route that was adopted in building a small AUV (Autonomous Underwater Vehicle). At the outset, we decided to follow a set of guidelines that defined a broad set of... more
Abstract: This paper contains a description of the mechanical design route that was adopted in building a small AUV (Autonomous Underwater Vehicle). At the outset, we decided to follow a set of guidelines that defined a broad set of specifications that featured safety, low weight, small length, large mission time, easy-to-use, application specific, and most importantly low cost. How closely did we arrive at this desired set of specifications? The paper will address the most important design issues, lessons learned, and problems that remain for further development.
PROJEMAR S. A., a naval and offshore design company at Brasil has developed several conversion projects of FPSO’s to operate at Campos Basin. This way, PROJEMAR faced some interface difficulty in the structural design of the topside... more
The prediction of roll motion of a ship with bilge keels is particularly difficult because of the nonlinear characteristics of the viscous damping. Flow separation and vortex shedding caused by bilge keels significantly affect the roll... more
The prediction of roll motion of a ship with bilge keels is particularly difficult because of the nonlinear characteristics of the viscous damping. Flow separation and vortex shedding caused by bilge keels significantly affect the roll damping and the magnitude of the roll response. To predict free response of roll, the Slender-Ship Free-Surface Random Vortex Method (SSFSRVM) developed in Seah & Yeung (2008) [1] was employed. It is a fast free-surface viscous-flow solver designed to run on a standard desktop computer. It features a quasi-three dimensional formulation that allows the decomposition of the three-dimensional hull problem into a series of two-dimensional computational planes, in which the two-dimensional free-surface Navier-Stokes solver FSRVM [2] can be applied. This SSFSRVM methodology has recently been further developed to model multi-degrees of freedom of free-body motion in the time domain. In this paper, we will first examine the effectiveness of SSFSRVM modeling b...
