bluuebunny/crossref_metadata_2025 huggingface dataset:
Toegankelijkheid openbare ruimte, regels en realiteit
Authors: Houtzager D.C.
Published: December 2021

Toegankelijkheid openbare ruimte, regels en realiteit

In 2022 treedt de Omgevingswet in werking, de belangrijkste nieuwe wet voor de inrichting van openbare ruimte. Regelen de wet en de bijbehorende regelingen ook toegankelijkheid voor mensen met een beperking? Dit artikel gaat in op die vraag, door eerst te kijken naar de huidige Wet ruimtelijke ordening (Wro) en vervolgens in te gaan op de Omgevingswet. In de Wro en aanhangende regelgeving wordt geen aandacht aan toegankelijkheid besteed. In de Omgevingswet wel, maar het is de vraag of de regeling robuust genoeg is om het verschil te maken. Gemeenten hebben vrijheid om op lokaal niveau toegankelijkheidsregels te stellen. Twee steden zijn onderzocht, Almere en Utrecht. Zij maken, met verschillende ambities, gebruik van de beleidsruimte om toegankelijkheid van straten en stoepen te verbeteren.
Peer Assessment in Parliament
Authors: Schobess Richard
Published: December 2021

Peer Assessment in Parliament

Peer assessment is a rather marginalised method in political research. This research note argues that the collective expertise of MPs can complement other data to contribute to more comprehensive evaluations of MPs’ parliamentary work. Yet, this method is potentially flawed by low survey participation and rater bias among MPs. The experience with a peer assessment survey among members of three Belgian parliaments shows that participation does not necessarily need to be problematic. However, the empirical analysis suggests that scholars should control for various forms of rater bias.
Cancelling proposed debates
Authors: Otjes Simon , Doedens Roy
Published: December 2021

Cancelling proposed debates

The Dutch Tweede Kamer is unique among parliaments because here the agenda is actually determined in a public, plenary meeting of all MPs. In the Dutch Tweede Kamer 30 members of parliament (MPs) can request a plenary debate. Many opposition parties request these debates, but only 23% of these are actually held. We examine the question ‘under what conditions do political party groups cancel or maintain proposals for minority debates?’ as a way to gain insight into the black box of parliamentary agenda setting. We examine two complementary explanations: issue competition and parliamentary style. We trace all 687 minority debates that were proposed between 2012 and 2021 in the Netherlands. This allows us to see what proposals for debates MPs make and when they are retracted. We find strong evidence that anti-elitist parties maintain more debate proposals than do other parties
The Determinants of Committee Membership in Belgium and the Netherlands
Authors: Mickler Tim
Published: December 2021

The Determinants of Committee Membership in Belgium and the Netherlands

In this article I analyse whether differences in formal committee structures affect how parliamentary actors organise their work within them. I compare the allocation of members to specialised committees in the Dutch House of Representatives (Tweede Kamer) and the Belgian Chamber of Representatives (Kamer van Volksvertegenwoordigers/Chambre des Représentants) to test whether committee assignments are given more serious consideration when committees are strong. Despite many similarities, both parliaments differ in their internal institutional arrangements: committees in the Chamber of Representatives are, at least formally, considerably more powerful than those in the Dutch Lower House. The article uses the congressional theories of legislative organisation as heuristic devices to deduce several rationales of the assignment process. The role of parliamentary party groups is highlighted. The results indicate the presence of stable, reoccurring patterns in both parliaments. Even in the House of Representatives, where committees present lower opportunity structures, assignments are given due consideration.
‘Think Like Me, and I Will Trust You’
Authors: Marié Awenig , Talukder David
Published: December 2021

‘Think Like Me, and I Will Trust You’

Do citizens with a lower level of political representation evaluate political actors more negatively? While the literature has documented inequalities in political representation, less attention has been given to the extent to which different levels of representation affect citizens’ levels of political trust. We aimed to fill this gap by analysing whether Belgian citizens with a lower level of policy opinion congruence with their party’s legislators have lower levels of trust in the parliament. Our results show that policy opinion congruence has a positive impact on citizens’ political attitudes. Indeed, citizens with policy preferences closer to those of their political representatives tend to have higher levels of trust in the parliament. This rela‍tionship depends on political sophistication: policy opinion congruence affects political trust for most citizens except those who consider themselves to be ‘very interested’ in politics. Citizens with a very high level of interest in politics trust the parliament regardless of policy opinion congruence with their party’s legislators.
Geestelijk letsel naar objectieve maatstaven; een in de psychiatrie erkend ziektebeeld is niet vereist
Authors: Kock L.A.J.
Published: December 2021

Geestelijk letsel naar objectieve maatstaven; een in de psychiatrie erkend ziektebeeld is niet vereist. HR (strafkamer) 29 juni 2021, ECLI:NL:HR:2021:1024

Op 29 juni 2021 heeft de Hoge Raad zich (opnieuw) uitgelaten over de vraag wanneer sprake is van aantasting in de persoon ‘op andere wijze’, als bedoeld in artikel 6:106 aanhef en onder b BW. In het bijzonder heeft de Hoge Raad zich nader uitgelaten over de invulling van het vereiste dat het bestaan van geestelijk letsel naar objectieve maatstaven moet zijn vastgesteld.
Online education of students with mild intellectual disability and autism spectrum disorder during the COVID-19 pandemic in the opinion of teacher
Authors: Buchnat Marzena , Wojciechowska Aneta
Published: December 2021

Online education, introduced obligatorily during the COVID-19 pandemic, poses a great challenge for teachers, students and their parents. Children and adolescents with mild intellectual disability or with ASD, that due to their cognitive deficits need appropriate support, are in a particular difficult situation. The aim of the conducted research was to specify the possible problems of online education of students with mild intellectual disability and ASD in their teachers' opinion. The research consisted in answering the questions from an online questionnaire. 114 teachers teaching children and adolescents with mild intellectual disability and 114 teachers teaching children and adolescents with ASD participated in the research. The results show that according to the teachers the biggest problems of students with mild intellectual disability and ASD are: understanding and remembering new material, lack of contact with their peers. Students with ASD are characterized by significantly greater intensity of the occurrence of difficulties in the area of education than people with mild intellectual disability. Difficulties in both groups of examined children and adolescents oblige to appropriately support them in online education and cooperation with their parents.
Mothers' perspective on the functioning of a family with a child with special communication needs – preliminary research
Authors: Konieczna Iwona
Published: December 2021

This article presents the results of preliminary research on the mothers’ perspective on the functioning of a family with a child with special communication needs. The goal was to gain an insight into the experiences of mothers of children with special communication needs in different areas of life and to understand the factors that influence their experiences.

The following areas of the mothers’ experiences in the functioning of a family were identified: the doing everyday activities, spending free time, relationships between family members and mothers' ideas about the future of a family with a child with special communication needs. The research employed individual case studies and the in-depth interview technique.
PROBABILISTIC SAFETY OF ESTUARY VESSELS BASED ON NONLINEAR ROLLING IN WIND AND WAVES
Authors: Bačkalov I
Published: December 2021

The author was previously involved in the development of the risk-based stability analysis which is now further extended, and used for the safety assessment of estuary container vessels subjected to stochastic action of beam wind and irregular waves. The study was motivated by the new set of safety regulations for estuary vessels issued by Belgian authorities in cooperation with Lloyd’s Register. These regulations introduce very innovative probabilistic ideas to ship stability regulations, and therefore present a significant step forward compared to the classical approach. Still, they do not account properly some important influences, such as wind gusts and motion nonlinearities, so considerably simplify the problem. The present investigation models the vessel motion much more realistically, analyzes the influence of beam wind and beam waves on the probability of a stability failure, and argues whether simplifications proposed by the regulations were justified. It is believed that presented method is not limited to the safety of estuary vessels only, but also gives important guidelines for a more general investigation of ship safety in wind and waves.
THE EXTENSION OF SYSTEM BOUNDARIES IN SHIP DESIGN
Authors: Hagen A , Grimstad A
Published: December 2021

In this paper we address the challenges arising from the public pressure to curb greenhouse gas emission from shipping. The shipping industry must expect that inefficiencies or sub-optimality in the transport systems will be curbed or punished severely. We present available technology to improve energy efficiency, and argue that decisions to apply such technology in a design process have to consider the vessel in its operational setting. We further discuss how this affects existing or introduces new design parameters. In the new situation, the relationship between a ship and its intended mission cannot be “broken” by a contractual document, such as a requirements specification. A ship designer needs to engage in the use of the ship, moving from being a ship designer to participating directly in a transport system design. In the paper we propose some amendments to existing models, and the framework of design tools, that facilitate this change.
THEORETICAL METHOD OF THE OPTIMUM DESIGN OF A SUPERCAVITATING PROPELLER BLADE WITH SPOILER MOUNTED ON THE TRAILING EDGE
Authors: Win Zaw , Fridman G M , Achkinadze A S
Published: December 2021

This paper presents theoretical design method to obtain 2-D optimum section with spoiler mounted on the trailing edge of a supercavitating propeller blade. Matched Asymptotic Expansions (MAE) is applied to determine the geometry of profile and cavity shape in the framework of potential flow theory. The blade section is of wedge-like shape and the opened cavity closure scheme is adopted. A typical section, on which the optimum blade design will be based, is singled out among the best individual sections from root to tip. The spoiler length of each hydrofoil section resulting from MAE method are finalized with CFD method so as to consider viscous effect under the same lift condition, others hydrofoil geometries being kept constant. The hydrodynamic performances of all blade sections being designed on the basis of the resulting typical section from linearized method are finally predicted with CFD method.
DISCUSSION: THE EXTENSION OF SYSTEM BOUNDARIES IN SHIP DESIGN
Authors: Hagen A , Grimstad A
Published: December 2021

This paper is to be welcomed as it argues for the broadening of ship design from what has generally been too narrow a focus in most cases due to the ship design process being a largely evolutionary approach. Given current environmental preoccupations, the authors’ approach is strongly driven by concerns over sustainability, in contrast some other broadening approaches have, for example, done so with an emphasis on ship architecture [23, 24]. Thus the authors’ approach seeks to make the profession recognise that even at the preliminary stages of ship design that it is complex and challenging but more appropriate in having a wider boundary than a directly (or simplistically) economic one.
EVALUATION OF CAVITATION PERFORMANCE OF AN AXI-SYMMETRIC BODY WITH PUMPJET PROPULSOR
Authors: Suryanarayana Ch , Nageswara Rao M , Suryanarayana B , Ramji K
Published: December 2021

A Pumpjet (PJP) was designed for an underwater body (UWB) with an axi-symmetric configuration as part of a technology development program for design and development of pumpjet. Its propulsive and cavitation performances were predicted through CFD study. The propulsor design was evaluated for its propulsion characteristics through model tests conducted in a Wind Tunnel. In the concluding part of the study, evaluation of the cavitation performance of the pumpjet was undertaken in a Cavitation Tunnel (CT).

In order to assess the cavitation free operational speeds and depths of the vehicle with respect to pumpjet, cavitation tests of the PJP were carried out in behind condition at CT to determine the cavitation inception numbers for rotor, stator and cowl. The model test results obtained were corrected for full scale Reynolds number and subsequently analyzed for cavitation inception speeds at different operating depths. This entire exercise facilitated the development of an innovative testing technique and a special test setup for finding cavitation performance of pumpjet propulsor. The technique was evaluated by comparative corroboration of inception position and depth obtained from CFD analysis. From the model tests it was also found that the cavitation inception of the rotor takes place on the tip face side at higher advance ratios and cavitation shifts towards the suction side as the shaft rotation rate increases whereas the stator and cowl are free from any cavitation.
SHIP MOTIONS DURING REPLENISHMENT AT SEA OPERATIONS IN HEAD SEAS
Authors: Thomas G , Turner T , Andrewartha T , Morris B
Published: December 2021

During replenishment at sea operations the interaction between the two vessels travelling side by side can cause significant motions in the smaller vessel and affect the relative separation between their replenishment points. A study into these motions has been conducted including theoretical predictions and model experiments. The model tests investigated the influence of supply ship displacement and longitudinal separation on the ships’ motions. The data obtained from the experimental study has been used to validate a theoretical ship motion prediction method based on a 3-D zero-speed Green function with a forward speed correction in the frequency domain. The results were also used to estimate the expected extreme roll angle of the receiving vessel, and the relative motion between the vessels, during replenishment at sea operations in a typical irregular seaway. A significant increase in the frigate’s roll response was found to occur with an increase of the supply ship displacement, whilst a reduction in motion for the receiving vessel resulted from an increase in longitudinal separation between the vessels. It is proposed that to determine the optimal vessel separation it is vital that the motions of the vessels are not considered in isolation and all motions need to be considered for both vessels simultaneously.
LIFE-CYCLE CO2 EMISSIONS OF BULK CARRIERS: A COMPARATIVE STUDY
Authors: Gratsos G A , Psaraftis H N , Zachariadis P
Published: December 2021

The paper contributes a reasoned methodology and useful data to the debate that is taking place in the context of rational Goal Based Standards. It is hoped that the paper will generate further debate which should eventually lead to generally accepted conclusions on meaningful minimum design and classification rule standards.
EXPERIMENTAL AND NUMERICAL STUDY ON PROGRESSIVE FLOODING IN FULL-SCALE
Authors: Ruponen P , Kurvinen P , Saisto I , Harras J
Published: December 2021

Generally speaking, I think that the paper is of good quality. The work performed is clearly described and is original since I am not aware any other such experiments at full scale. Please find below some more detailed comments and questions to the authors:
STUDY OF FROUDE AND HUGHES METHODS BY NUMERICAL TOWING TANK
Authors: Gao Q , Vassalos D
Published: December 2021

The resistance of a cargo ship is calculated by numerical towing tank. RANSE multi-phase parallel solver with K-Z SSTturbulent model and VOF formulation is applied. Computational results from double model (without free surface) areused to obtain 1+k in Hughes’ method and those with free surface are analyzed by both Froude and Hughes’ approachesto investigate model and full scale correlation. ITTC recommended uncertainty study is carried out to evaluate numericalerror due to grid density. The computed wave elevation, wake distribution and resistance components by fine, mediumand coarse meshes are cross-compared and validated against experiment data where applicable. It is found that gridresolution has most effect on wave pattern. The predicted friction and viscous-pressure resistance coefficients arerelatively grid independent from present numerical simulation.
A STUDY ON VISCOUS ROLL DAMPING OF A BOX-SHAPED VESSEL IN THE FREQUENCY DOMAIN USING THE DISCRETE VORTEX METHOD
Authors: Hajiarab M , Downie M , Graham M
Published: December 2021

This paper presents a study on viscous roll damping of a floating box-shaped vessel in the frequency domain. The application of the discrete vortex method (DVM) for calculation of the viscous roll damping in regular seas has been validated by model tests. Equivalent roll RAOs associated with a range of regular wave amplitudes are calculated to assess behaviour of the viscous roll damping in relation to incident wave amplitude linearisation. A model test is conducted using the model test facilities of the Marine Hydrodynamics Laboratory at Newcastle University to validate the applicability of the DVM in calculating the roll RAO in regular waves and to study the application of this method to irregular waves. Results of these model tests are presented in this paper.
SUBCRITICAL WAVE WAKE UNSTEADINESS
Authors: Robbins A , Thomas G A , Renilson M R , Macfarlane G J , Dand I W
Published: December 2021

Vessel wave wake in deep water is well understood, shallow water less so, specifically the effect of restricted water. This operational zone is highly dynamic and non-linear in nature, thus being worthy of closer examination. The paper reviews the primary mechanisms for unsteadiness in wave wake: starting acceleration and soliton generation. A comprehensive set of experiments was conducted using an NPL catamaran hull form to investigate unsteadiness in both wave height and wave angle. The results show that the unsteadiness was primarily due to soliton generation, and that blockage has a significant effect. As a result, additional metrics, aimed at defining shallow water effects in the transcritical region, are proposed.
COMPARISON OF LAND-BASED TEST SETUPS FOR A BALLAST WATER MANAGEMENT SYSTEM
Authors: Pazouki K , Carney K J , Delany J , Mesbahi E
Published: December 2021

Two land-based setups were tested at different locations using the same combined treatment technologies, to assess the effect of different control and treated tanks condition as well as overall effectiveness of a ballast water treatment system. The test procedure included a five day storage period of organisms in the control and treated tanks as specifically advised in the type approval procedure for shipboard and land-based tests described in the IMO Guideline ‘G8’. The configurations and materials of control and treated tanks used in each test location were different resulting in invalid test results at one testing location.
EFFECT OF DOUBLE BOTTOM HEIGHT ON THE STRUCTURAL BEHAVIOUR OF BULK CARRIERS
Authors: Contraros P D , Phokas S P
Published: December 2021

This is the first of a series of companion papers that the authors propose to present on the effect that the new CSR Rules will have on the design of bulk carriers. Our initial focus will be on the new design framework established for the inner bottom height of such vessels, a parameter critical to their structural integrity. It examines the effect that double bottom height reduction has on the reliability of the bulk carrier structure, by applying a finite element 3D - 3 hold analysis of varying double bottom heights to a typical current Panamax bulk carrier design. The results are compared to pre and post IACS CSR[2] requirements. The conclusion reached is that the establishing of the double bottom height should not be left to direct calculations. A minimum acceptable height should be established in order to maintain a minimum level of structural reliability and safety.
PROPELLER CAVITATION AND INDUCED VIBRATION
Authors: Leontopoulos C , Lee S K , Karaminas L
Published: December 2021

The demand to increase the efficiency of propellers has led to optimized propeller blade designs finding their way into the construction of high-powered commercial vessels, such as containers or LNG carriers and certain categories of passenger vessels, to mention but a few. It has become increasingly common to see the propeller tip rotate closer to the hull surface, sweeping the thick turbulent boundary layer attached to the hull, causing fluid structure interaction. At the same time, increasing the loading on marine propellers can lead to problems, such as noise, hull vibration, and cavitation. The degree above which, such phenomena as propeller cavitation can be the main perpetrators for intensive vibration during operation, their diagnosis and the solutions to mitigate this risk, such as the use of vortex generators, are discussed here, taking into account cost and longevity of the vessel as well as the involvement of classification rules.
A NEW METHOD FOR ASSESSING THE SAFETY OF SHIPS DAMAGED BY GROUNDING
Authors: Paik J.K. , Kim D.K. , Park D.H , Kim H.B. , Kim M.S.
Published: December 2021

The primary aim of the present study is to propose an innovative method for assessing the safety of ships which have suffered accidental or in-service damages. Only a small number of probable scenarios for accidental or in-service damage representing all possible damage scenarios are selected using a sampling technique in which the random variables affecting the damage are probabilistically characterized. A damage index for the corresponding damage scenario is defined as a function of damage characteristics such as location and extent of the damage. The residual strength performance of a ship with the corresponding damage scenario can then be calculated by analytical or numerical methods. Once this process has been carried out for each of the damage scenarios selected, a diagram relating the residual strength performance to the damage index (abbreviated as the R-D diagram) can be established. This diagram will be very useful for a first-cut assessment of a ship’s safety immediately after it has suffered structural damage. The diagram can also be used to determine acceptance criteria for a ship’s safety against accidental or in-service damage. An applied example is shown to demonstrate the applicability of the proposed method in terms of developing a diagram between the ultimate longitudinal strength versus grounding damage index for four types of double-hull oil tankers – VLCC, Suezmax, Aframax, and Panamax.
REDUCING FUEL USAGE AND CO2 EMISSIONS FROM TUG BOAT FLEETS: SEA TRIALS AND THEORETICAL MODELLING
Authors: Murphy A J , Weston S J , Young R J
Published: December 2021

Sea trials on a harbour tug have been conducted and are explained. The experimental results for fuel consumption per unit transport effort, under free-running (transiting) conditions, are presented and engine speed-propulsor pitch combinations for improved fuel economy are identified. A simplified analytical approach to predict fuel consumption, including the coupled engine-propulsor-hull system, is described. This rationale is combined with experimental observations and, consequently, performance maps present the complete operating envelopes of the harbour tug under both free-running and towing conditions. This combined approach proved to be effective and can be applied to the study of other tug vessels. As a consequence of this research, the engine control system on the harbour tug was modified to permit it to operate fully within the region of best fuel economy during free-running. The results from the bollard-pull predictions provide insight for the design and operation of harbour tugs in the future.
IDENTIFICATION OF INFLUENTIAL PARAMETERS IN A SHIP’S MOTION RESPONSES: A ROUTE TO MONITORING DYNAMIC STABILITY
Authors: Enshaei H , Birmingham R , Mesbahi E
Published: December 2021

Six degrees of freedom motion response tests of a Ro-Ro model have been carried out in irregular waves under intact conditions. A stationary model was tested in different sea states for following, astern quartering and beam seas. The investigation was limited to the effect of encountered frequency components and associated magnitude of energy of the ship’s motion responses. Analysis of heave, pitch and roll motions confirmed the vulnerability of the model to certain frequency ranges resulting in an adverse effect on the responses, and these were closely related to its natural frequencies. It was confirmed that the roll motion maintains its highest oscillation around the natural frequency in all sea conditions regardless of heading angles. However spectral analysis of the heave and pitch responses revealed the wave peak frequency. Roll is magnified when the peak frequency of wave approaches the natural roll frequency; therefore keeping them apart avoids a large motion response. It was concluded that peak frequency and associated magnitude are two important inherent characteristics of motion responses. Detection of influential parameters of encountered wave through heave and pitch responses could be utilised to limit a large ship’s motion at sea.
THE FLOODING AFTER DAMAGE OF A WARSHIP WITH COMPLEX INTERNAL COMPARTMENTS – EXPERIMENTS ON A FULLY CONSTRAINED MODEL IN CALM WATER AND REGULAR BEAM SEAS
Authors: Macfarlane G J , Renilson M R , Turner T
Published: December 2021

In order to provide data to assist in developing and validating a numerical code to simulate the flooding immediately following damage scale model experiments were conducted on a fully constrained model to investigate the progressive flooding through a complex series of internal compartments within a generic destroyer type hull form.

A 3.268 metre long model of a generic destroyer hull form with a simplified, typical internal arrangement was constructed to cover the configuration of greatest interest. A very rapid damage opening scenario was simulated by rupturing a taut membrane covering an opening. The model was instrumented to measure the levels of water and the air pressures in various compartments. In addition, video footage was obtained of the flooding process from both internally and externally of the model.

Previous work presented by Macfarlane et al. (2010) showed the results for the unconstrained model. This paper reports on the outcomes from the experimental program where the model was fully constrained in all six degrees of freedom. Firstly, tests were conducted in calm water with damage opening extents ranging from 50% to 100%. When the damage opening was only 50% the rate of rise of water in each of the compartments was only marginally slower than for the 100% damage extent case.

Secondly, the test results in calm water were compared against results from tests in regular beam seas. A ‘set-up’ of water inside each of the compartments on the 2nd Deck was found during the wave tests. The result of this is that the mean equilibrium water level in each compartment in the regular beam sea cases is noticeably higher than the equivalent calm water case, particularly for the two compartments on the port side, away from the damage. Finally, analysis of the data from further calm water and beam sea tests suggests that a similar result also occurs when the model is fixed at various non-zero heel angles.
A REVIEW OF PRACTICAL METHODS FOR REDUCING UNDERWATER NOISE POLLUTION FROM LARGE COMMERCIAL VESSELS
Authors: Leaper R C , Renilson M R
Published: December 2021

Underwater noise pollution from shipping is of considerable concern for marine life, particularly due to the potential for raised ambient noise levels in the 10-300Hz frequency range to mask biological sounds. There is widespread agreement that reducing shipping noise is both necessary and feasible, and the International Maritime Organization is actively working on the issue. The main source of noise is associated with propeller cavitation, and measures to improve propeller design and wake flow may also reduce noise. It is likely that the noisiest 10% of ships generate the majority of the noise impact, and it may be possible to quieten these vessels through measures that also improve efficiency. However, an extensive data set of full scale noise measurements of ships under operating conditions is required to fully understand how different factors relate to noise output and how noise reduction can be achieved alongside energy saving measures.
ON THE APPLICATION OF THE EXTREME VALUE THEORY IN SHIP’S STRENGTH CALCULATIONS
Authors: Ivanov L D
Published: December 2021

A procedure is proposed for application of the extreme value theory (EVT) approach considering not only the maximal value of the corresponding random variable but also its probability of exceedance. It substantially reduces the probability of exceedance of any given limit value used in the case when traditional EVT is applied. Examples are provided to illustrate its application when records of the random process are available.
RECURSIVE NEURAL NETWORK MODEL OF CATAMARAN MANOEUVRING
Authors: Moreira L , Guedes Soares C
Published: December 2021

A neural network model to simulate catamaran manoeuvres is proposed as an alternative to the traditional methodology of developing manoeuvring mathematical models. Data obtained in full-scale trials with a real ship are used to train the model. By recording full-scale trials of catamaran manoeuvres it is possible to generate a neural network model which will allow the prediction of the catamaran manoeuvring performance under different conditions.

A Recursive Neural Network (RNN) manoeuvring simulation model is proposed and applied to a catamaran in this specific case. Inputs to the simulation are the orders of rudder angle and ship’s speed and also the recursive outputs velocities of sway and yaw. Two types of manoeuvres are simulated: tactical circles and zigzags. The results between the full-scale data and the simulations are compared in order to analyze and determine the accuracy of the RNN. The study is performed for a catamaran operating in the Tagus estuary for passenger transport to and from Lisbon.
ANALYSIS OF THE WATER IMPACT OF SYMMETRIC WEDGES WITH A MULTI- MATERIAL EULERIAN FORMULATION
Authors: Wang S , Guedes Soares C
Published: December 2021

The two-dimensional hydrodynamic problem of a symmetric wedge vertically impacting in calm water is analysed by using an explicit finite element method based on a multi-material Eulerian formulation. The slam-induced loads on wedges with different deadrise angle at a constant velocity are calculated, including pressure distribution, maximum pressure coefficient, force coefficient and time history of vertical force, which are compared with available theoretical and analytical results. The time evolution of pressure distribution and free surface elevation are presented. Furthermore, the effects of impact velocity are investigated. It shows that this method is capable of predicting the local slamming loads, and as well assessing the effects of the deadrise angle and the impact velocity on the slamming pressure for the wedge-shape section.
FATIGUE ASSESSMENT OF CORRODED DECK LONGITUDINALS OF TANKERS
Authors: Parunov J , Gledić I , Garbatov Y , Guedes Soares C
Published: December 2021

Fatigue life of deck longitudinals of oil tankers is analysed based on linear elastic fracture mechanics. A parametric formulation for the estimation of stress intensity factors and the Paris-Erdogan law are applied. Long-term effects of corrosion are modelled based on regression equations fitted to thickness measurements made during inspections of two tankers. Parametric studies are performed in order to investigate the importance of the governing parameters of crack propagation. A comparison of the fatigue analyses performed by linear fracture mechanics and S-N approaches is presented.
CFD-BASED HYDRODYNAMIC ANALYSIS FOR A SHIP SAILING ALONG A BANK IN RESTRICTED WATERS
Authors: Zhou M G , Ma S J , Zou Z J
Published: December 2021

For a ship navigating along a bank in restricted waters, it is usually accompanied by obvious bank effect which may cause ship-bank collision. In order to avoid collision, it is necessary to provide control force and moment by using control devices such as a rudder. In this paper, CFD method is applied to numerically simulate the viscous flow around a ship appended with a rudder sailing along a bank. Systematical simulations are carried out for the hull-rudder system with different rudder angles at different ship-bank distances and water depths. The flow field features and the hydrodynamic forces of the hull-rudder system are obtained and analysed. This study is of significance for revealing the physical mechanism behind the bank effect and providing guidance for ship steering and control in restricted waters.
SET-UP DUE TO RANDOM WAVES: INFLUENCE OF THE DIRECTIONAL SPECTRUM
Authors: Barbaro G , Foti G , Malara G
Published: December 2021

The correct estimation of set-up is very important to evaluate coastal hazard and to design coastal structures. In this paper, we derived a mathematical expression for wave set-up in the context of random waves. The solution to this expression assumes straight, parallel depth contours and constant average flow parameters in the longshore direction. We then investigated the effect of different types of sea state taking account of different frequency spectrum and spreading function assumed in the expression on estimates of wave set-up. We found the set-up was highly influenced by the frequency spectrum used. Finally, we applied this expression to estimate set-up values at locations in Italy and in the United States using buoy data provided by ISPRA (Istituto Superiore per la Protezione e la Ricerca Ambientale) and NDBC (National Data Buoy Centre).
CFD-BASED HYDRODYNAMIC ANALYSIS FOR A SHIP SAILING ALONG A BANK IN RESTRICTED WATERS
Authors: Zhou M G , Ma S J , Zou Z J
Published: December 2021

The paper is interesting, good structured and deals with an important problem concerning ship behaviour in restricted water. The use of a CFD method as FLUENT (code also used at Ghent University) shows the possibilities of numerical methods for the calculation of ship-bank interaction. The content could still be improved as some topics in the paper miss some depth.
NUMERICAL AND EXPERIMENTAL STUDY OF THE PARAMETRIC ROLLING OF A FISHING VESSEL IN REGULAR HEAD WAVES
Authors: Uzunoglu E , E Silva S. Ribeiro , Guedes Soares C. , Zamora R. , Perez Rojas L.
Published: December 2021

The dynamic behaviour of a fishing vessel in waves is studied in order to reveal its parametric rolling characteristics. This paper presents experimental and numerical results in longitudinal regular waves. The experimental results are compared against the results of a time-domain non-linear strip theory model of ship motions in six degrees-of-freedom. These results contribute to the validation of the parametric rolling prediction method, so that it can be used as an assessment tool to evaluate both the susceptibility and severity of occurrence of parametric rolling at the early design stage of these types of vessels.
STUDY ON PROPULSIVE PERFORMANCE OF TWO GEOMETRICALLY SIMILAR PODDED PROPULSORS
Authors: Islam M , Akinturk A , Veitch B , Liu Pengfei
Published: December 2021

This paper presents the outcome of a research to evaluate the effect of size on the propulsive performance of podded propulsors in cavitating and non-cavitating open water conditions. Two cases are examined, namely: propeller-only case and pod-unit case. In the propeller-only case, a commercial propeller dynamometer is used to measure the thrust and torque of two propellers of different size at the four quadrants of propellers with varied shaft and flow speeds. Also, both propellers are tested at different tunnel pressure to study and compare the behaviour under similar cavitation conditions. In the pod-unit case, two geometrically similar but different sized pod-units are tested using two separate custom-made pod dynamometer systems in two towing tank facilities in straight-ahead and static azimuthing conditions. The study showed that the performance characteristics stabilize at lower Reynolds Number for the smaller propeller than the larger propeller. The propulsive performance of the two propellers was comparable in the four-quadrant experiments. Also, the experiments at the cavitating conditions showed that the cavitation characteristics of the two propellers were consistent at corresponding operating conditions. The experiment results of the two pod-units were also comparable for forces and moments in the three coordinate directions in the straight-ahead and static azimuthing conditions. A brief discussion on the uncertainty assessments for each of the measurements is also presented.
AN APPROXIMATE METHOD TO PRESENT THE BUCKLING STRENGTH OF A GRILLAGE IN A PROBABILISTIC FORM
Authors: Ivanov L D. , Lokshin A Z. , Mishkevich V G.
Published: December 2021

An approximate method for calculation in probabilistic terms of the buckling strength of a grillage under unidirectional in-plane compression is proposed. The geometric properties of longitudinals and transverses and the mechanical properties (yield stress and modulus of elasticity) of the material they are built from are treated as random parameters that may change over ship’s service life. The cumulative distribution function of the grillage’s critical buckling strength is calculated by using an analytical formula for multitude sets of input parameters while all of them having the same level of certainty. The assumption is that the critical buckling strength has the same (or very similar) level of certainty as that of the input parameters. The accuracy of the proposed approximate method is relatively high (the maximal error is around 2%). It is recommended for use when specialized computer programs for application of Monte Carlo simulation method are not ￼available. The method does not require a complicated specialized computer program and can be run on EXCEL computer program.
SLAM CHARACTERISTICS OF A HIGH-SPEED WAVE PIERCING CATAMARAN IN IRREGULAR WAVES
Authors: French B J , Thomas G A , Davis M R
Published: December 2021

Slam characteristics of a 112m INCAT wave piercing catamaran in a range of realistic irregular sea conditions are presented in this paper. Towing tank testing of a 2.5 m hydroelastic segmented catamaran model was used to gather a database of slam events in irregular seas. The model was instrumented to measure motions, centrebow surface pressures and forces, encountered wave elevations and wave elevations within the bow area tunnel arches. From these measurements characteristics of the vessel slamming behaviour are examined: in particular relative vertical velocity, centrebow immersion, archway wave elevations and slam load distributions. A total of 2,098 slam events were identified over 22 different conditions, each containing about 80 to 100 slam events.

The data, although inherently scattered, shows that encounter wave frequency and significant wave height are important parameters with regard to centrebow slamming. Relative vertical velocity was found to be a poor indicator of slam magnitude and slams were found to occur before the centrebow arch tunnel was completely filled, supporting the application of a two-dimensional filling height parameter as a slam indicator.
HAZARD IDENTIFICATION AND PROBABLISTIC SCENARIO SELECTION FOR SHIP- SHIP COLLISION ACCIDENTS
Authors: Youssef S. A. M. , Kim Y. S. , Paik J. K. , Cheng F. , Kim M. S.
Published: December 2021

In collision risk-based design frameworks it is necessary to accurately define and select a set of credible scenarios to be used in the quantitative assessment and management of the collision risk between two ships. Prescriptive solutions and empirical knowledge are commonly used in current maritime industries, but are often insufficient for innovation because they can result in unfavourable design loads and may not address all circumstances of accidents involved. In this study, an innovative method using probabilistic approaches is proposed to identify relevant groups of ship-ship collision accident scenarios that collectively represent all possible scenarios. Ship-ship collision accidents and near-misses recently occurred worldwide are collated for the period of 21 years during 1991 to 2012. Collision scenarios are then described using a set of parameters that are treated individually as random variables and analysed by statistical methods to define the ranges and variability to formulate the probability density distribution for each scenario. As the consideration of all scenarios would not be practical, a sampling technique is applied to select a certain number of prospective collision scenarios. Applied examples for different types of vessels are presented to demonstrate the applicability of the method.
CONCEPT DESIGN FOR A SUEZMAX TANKER POWERED BY A 70 MW SMALL MODULAR REACTOR
Authors: Hirdaris S E , Cheng Y F , Shallcross P , Bonafoux J , Carlson D , Sarris G A
Published: December 2021

The authors are to be congratulated on a well- researched and timely technical paper. I am pleased to express my personal opinion on the subject.

COSCO was intending to initiate a study in December 2009 on nuclear powered ship design in order to reduce GHG emissions from shipping. However, this plan was aborted three years after, following the catastrophic accident at the Fukushima nuclear power station in Japan during March 2011. This intensified political and public opposition to nuclear power to the extent that Germany has since adopted plans to decommission its entire nuclear infrastructure. However, confidence is beginning to re- emerge - confidence which I share. With increasing attention being given to GHG emissions arising from burning fossil fuels for global aviation and marine transport, together with the excellent safety record of nuclear power in the marine environment and the development of the new generation of SMRs, it is quite conceivable that renewed attention will be given to the application of nuclear power in merchant ship propulsion.

In producing this paper, the authors have made a significant contribution in the field of innovative ship design development. They have demonstrated the feasibility of applying the latest generation of nuclear reactor to commercial ship propulsion. Whereas nuclear power has been widely used in vessels of a number of navies and icebreakers, it has yet to be adopted for commercial ships other than a small number of research projects. This paper has provided good rationale for accommodating nuclear power in merchant shipping including speed and range requirements, required specific volume on board, environmental considerations etc. The study has also considered the risks associated with design and the arrangement of nuclear systems including location of the SMR, type of propulsion options and other safety- critical issues, not least the radiological risk to persons on board, involved in maintenance and in port.
ASYMMETRICAL WATER IMPACT OF TWO-DIMENSIONAL WEDGES WITH ROLL ANGLE WITH MULTI-MATERIAL EULERIAN FORMULATION
Authors: Wang S , Guedes Soares C
Published: December 2021

A hydrodynamic study on the asymmetrical water impact of two-dimensional wedges with roll angle is presented. The slam induced loads on the wedges entering calm water with both vertical and horizontal velocities are predicted based on the explicit finite element method. The effects of the horizontal impact velocity and the roll angle are investigated through the predicted results of pressure distribution, pressure variation during the water entry and total impact force, which are also compared with analytical formulations and other numerical calculations. The present method gives reasonable predictions, compared to the numerical and analytical results.
EFFECT OF WATERTIGHT SUBDIVISION ON DAMAGE STABILITY OF RO-RO FERRIES
Authors: Pawłowski M , Laskowski A
Published: December 2021

Effect of various subdivision arrangements of ro-ro vessels on damage stability is discussed. The arrangements included single and double sides both below and above the car deck, with and without a double buoyant car deck, and with or with- out a watertight tween deck below the car deck. This gave as many as 16 various arrangements for each compartment length. The double sides both above and below the car deck are of the same width b = 0.1B. The double bottom, when not flooded, worsens damage stability. The car deck and tween decks should be ‘openwork’, to be transparent for water and air. Oth- erwise, the ship can capsize at the very initial stages of flooding. Double sides and a double car deck together improve con- siderably damage stability, both in terms of maximum arm and range. A new characteristic was introduced, termed the critical deck height. Flooding a deck above the critical height leads to a rapid capsizing of the ship.
MULTIPARAMETRIC DIAGNOSTICS OF GAS TURBINE ENGINES
Authors: Sinay J , Tompos A , Puskar M , Petkova V
Published: December 2021

This article addresses the issue of diagnostics and maintenance of Gas Turbine Engines which are located in high Speed Ferries, Cruisers, Frigates, Corvettes, etc. Assurance of reliable operation can be performed only by using correct diagnostic methods and procedures of monitoring the condition of the devices and by selecting the correct strategy of maintenance. The issue of monitoring the technical condition of Gas Turbine Engines is treated through multiparametric methods of technical diagnostics incorporated into predictive maintenance, which is a part of proactive maintenance. There are methods of vibrodiagnostics, thermography, tribology, borescopy and emissions measurement. Each of these methods has lots of advantages and disadvantages; therefore it is very important to ensure their correct combination for trouble-free operation of those important facilities. Their suitability at work is discussed in the matrix of diagnostic methods application and the PF chart. The output of the work is a proposal of a suitable model of maintenance control which uses multiparametric diagnostic methods for small and big Gas Turbine Engines and optimizes maintenance costs.