bluuebunny/crossref_metadata_2025 huggingface dataset:
A meta-analysis of the effectiveness of the method of creative drama in math courses in regard to student scores in achievement, attitude and retention
Authors: Gülderen Alacapınar , Uysal Hatice
Published: January 2021

In this study, pretest-posttest control group design thesis in experimental models was investigated by meta-analysis for preschool , primary and secondary school mathematics classes based on creative drama method, between years 2000-2020 which are accepted by universities in Turkey. 3doctoral theses and 20 master's theses that are suitable for the problem of this research and have sufficient statistical data were included in the meta-analysis. In the analysis of data, meta-analysis of transaction effectiveness was used. In this study, the effect of creative drama method on students' academic achievement, retention(remembering) and affective (attitude) scores were examined. As a result of meta-analysis calculations, the effect size value of creative drama method on students' academic achievement scores was 0.926, the effect size on retention scores was 1.414 and the effect size value on attitude scores was 0.600. These values determined as a result of the analysis; shows that the effect size is wide for academic success and retention and medium for attitude. According to these findings, the academic success and retention of creative drama method in preschool and elementary mathematics lessons is wide; it can be said that it affects attitude at a moderate level significantly.
A novel concept for quantitative measurement of organizational performance index
Authors: Simon John , Mathews Samuel , Shetty Balachandra , Mishra R.K.
Published: January 2021

The performance of an organization depends on many dimensions of technology and management such as leadership, strategic planning, customer focus, process management, measurement, analysis, knowledge management, costing, financial management, and human resource management. However, the efficiency of the organization can be easily assessed from the organization's performance output compared to the set targets while other dimensions act as add-on catalysts in maximizing productivity. Hence, the measurement of the overall output of the organization as well as all its departments in any organizational hierarchy becomes very critical. A novel quantitative measurement methodology of the organizational output combining mathematical and statistical modeling on the bottoms-up approach is developed and explained in this paper. The concept can be used with existing enterprise resources and planning tools available in industries for the enhancement of their productivity.
The impact of project risk audits on construction project success
Authors: Obondi Kennedy
Published: January 2021

Risk audit is often poorly implemented in construction projects because of the absence of constant auditing of risks by construction project managers. Construction companies are experiencing large financial deficits because of managers failing to audit and monitor project risks. The purpose of this study was to examine whether the utilization of risk audit correlates with project success in construction projects. An electronic survey instrument was used to collect data from a sample of 50 construction project managers in the Dallas-Fort Worth area of Texas in the United States. Spearman's rho correlational analysis and simple logistic regressions were used to examine the relationship between risk audit and project success. The results of this study indicated that there is a positive and significant association between risk audit and project success in terms of schedule performance, cost performance, customer satisfaction, and business success. One of the recommendations presented in this study was to expand the study to developing countries to see whether the findings from the study remain the same. The study concluded that construction organizations should regularly consider the importance and usage of risk audit techniques to improve the success rate of a project.
Effects of different control variables on workplace bullying in organizations in Serbia
Authors: Stankov Sanja , Poštin Jasmina , Konjikušić Marko , Jagodić-Rusić Aleksandra , Stojković Hadži , Strukan Edin
Published: January 2021

This paper presents the results of the research of the six control variables impact on workplace bullying dimension and harassment items. Gender of respondents, Age of respondents, Education of respondents, National origin of the company, Ownership structure of the company, and Size of the company (number of employees) were used as control variables. The research was conducted through a survey with respondents, and respondents are employees in Serbian organizations, at different hierarchical levels. The sample included 536 questionnaires. T-test was applied to average ratings of the workplace bullying dimensions and and self-labelling (mistreatment) item and in compliance with the aforementioned control variables. It was indicated that workplace bullying is not present in organizations in Serbia to a large extent, but it is still higher than in some highly developed countries. The size of the company (number of employees) has been identified as the only, hence a very important factor in the emergence of workplace bullying in organizations in Serbia. Workplace bullying is more emphasized in large companies than in small ones. This phenomenon is discussed in the paper.
Implementation of 6R strategy in FDM printing process: Case: Small electronic enclosure box
Authors: Vorkapić Miloš , Hasan Mohammad , Tanović Dragoljub , Baltić Marija , Tomić Branislav
Published: January 2021

This paper provides an algorithm for the application of additive manufacturing in the sustainable development of the enterprise. The manufacturing process includes the process of manufacturing preparation, the process of realization of manufacturing (or remanufacturing), the end of the manufacturing process with additional processing and recycling process. A 6R strategy in the realization of new or redesign of existing elements/parts has been implemented. Additive manufacturing or FDM printing technology enables frequent and simple modification of the model at a customer's request, and prior to the model enters the manufacturing itself. The starting material for making the model was polylactic acid (PLA). This paper aims to present the procedure of the realization of an electronics enclosure for a miniature pressure transmitter on a 3D printer. This gives the designer the opportunity to correct existing errors, modify the product according to the requirements of end-users, or to design a completely new product (prototype). In order for the algorithm to get the right confirmation, it is important to design a product that enables: accessibility, easy interchangeability, disassembly, the possibility of finishing and reuse.
Women in Serbia: In the gap between patriarchal and new roles
Authors: Torlak Nada
Published: January 2021

Although we entered the third millennium many years ago, women in Serbia are still living in an imbalance between old, traditional roles and new values. Instead of being relieved of their traditional burdens, women in the 21st century seem to be experiencing even harder lives. Lost between old patriarchal relations and obligations, they have also acquired some new ones. In addition to the traditional (implicit) roles of wife, mother, and housewife, now the already common (covered in the movie) question arises: what do women want? To have families, careers, and leadership positions or all of these combined. However, this question is not only addressed to them, but to the wider social community and the state. Why? Because the old roles have remained while for new, professional positions women are expected to compete with men on an equal footing, with the exception of pay and a few other things. In this paper, we will try to answer these questions or at least point out the existing problems, including the already mentioned pay gap and the various challenges a modern woman in Serbia faces.
Anti-Serb war manifesto or to which aim are so-called non-governmental organizations used: An editorial
Authors: Redakcija R
Published: January 2021

The German state propaganda service Deutche Welle (DW), recently published a new anti-Serb war manifesto, also reported by the daily press in the Republic of Croatia. The aim of the document, whose basic ideas do not belong to the person interviewed, is the creation of conditions which would favor the breakout of a new Balkan war, primarily in the territory of Bosnia and Herzegovina, through the dissolution of the Republic of Serbia, treated incorrectly in the text as the "spoils of war" of Serbia. The purpose of the text is the weakening of the geopolitical position of Serbia through the following: 1) the severing of ties with the Serb population living in former Yugoslav republics (B&H, Montenegro); 2) the accepting of an unfavorable institutional solution for the Republic of Srpska through amendments to the Dayton-Paris peace agreement, whose guarantor is Serbia, as the successor of the FRY and Serbia & Montenegro; 3) the accepting of an unfavorable institutional solution for AP Kosovo and Metohija, whose status, until otherwise changed, is determined by Resolution 1244 of the UN Security Council; 4) the dragging of Serbia into North Atlantic integrations despite continued objections of Serbs to the idea and its proclaimed policy of military neutrality; 5) the breaking up of friendly relations and close cooperation of the Republic of Serbia with the Russian Federation and the People's Republic of China, which would cost our country the loss of the ability to defend almost all its vital state interests, including its territorial integrity and sovereignty, aside from losing the friendship of those who have in various situations come to our country's aid. According to the originator of this anti-Serb war manifesto, coerced, humiliated, and punished (unjustly), Serbia and the Serbs have the right to expect European integrations.
Taking analogy seriously: Statutory analogy in creation and interpretation of law
Authors: Dajović Goran
Published: January 2021

In the article, author analyzes analogy generally and analogy in law, as a way of reasoning. The traditional division of the application of analogy in law into analogia legis and analogia iuris is perceived as incomplete and insufficiently clarifying for what is really happening in the practice of law. Instead, as a starting point, it emphasizes the division of analogies in law into casuistic and statutory analogy. While in common law systems the former is more applied and studied, in continental legal systems, due to the primacy of written sources of law, it is more interesting to consider the latter. The statutory analogy is firstly analyzed from the aspect of its form and content (retrieval and mapping). After that, its basic types are described. The first is the analogy extra legem, which serves to fill legal gaps, or more precisely, which attributes legal consequences to facts that are not explicitly described in the applicable legal provision. The second type of statutory analogy is analogy intra legem, in which the argument of analogy is used to interpret legal norms. In the article are particularly depicted the two "incarnations" of analogy intra legem, extensive interpretation and systemic interpretative argument of analogy. Finally, through several cases from judicial practice of Serbian courts, it is illustrated how the statutory analogy is applied in this practice only intuitively, and therefore insufficiently explained, and, after all, incorrect.
Experimental Parametric Investigation to Reduce Drag of a Scaled Model of Bulk Carrier Using BDR/ALS Technique
Authors: Sindagi Sudhir , Vijayakumar R. , Saxena B. K.
Published: January 2021

The shipping business expects to develop energy-saving and drag-reducing techniques addressing the cost of shipping and environmental problems. It has been reported that for slow-moving vessels, frictional resistance accounts for up to 80% of the total resistance, needing urgent attention to reduce the same. To reduce frictional resistance, the air has been used as lubricant, which is injected below the moving body known as Bubble Drag Reduction or the Air Lubrication System. In this article, results obtained from experimental investigations into drag reduction of a 1:23 scaled model of an 8000-ton deadweight bulk carrier by injecting air bubbles below it are presented. Investigations were carried out for a speed range of 6–10 knots, and for each speed, the effect of six injection flow rates of .5–3.0 CFM were investigated. To investigate the effect of different sizes of injection holes, two types of injector units have been used: one with injection holes of 1 mm diameter and the other with injection holes of 2 mm diameter. The study carried out has many practical implications because it is easier to create bigger size holes which will reduce the power required to inject air, thereby increasing the efficiency of the entire technique.

Introduction

It is projected that crude oil prices will continue to increase in the future, forcing marine businesses to rely on researchers to develop energy-saving devices (ESD) and drag-reducing technologies. It has been reported that for slow-moving vessels such tankers, bulk carriers, very large crude carrier (VLCC), and ultra large crude carrier (ULCC), frictional resistance accounts for up to 80% of the total resistance, needing urgent attention to reduce the same (Lewis n.d.; Larsson & Raven 2010). Numerous technologies have been studied and applied in reducing the frictional drag (Brostow 2008; Abdulbari et al. 2013; Luo et al. 2015; Mohammad & Mousavi 2015; Sindagi et al. 2016). Based on further studies Sindagi et al. (2018a, 2018b, 2018c, 2018d) and Sindagi and Vijayakumar (2020), it is concluded that air lubrication has additional advantages over other technologies, such as it is environmentally friendly, the operation is quite easy, and it results in low operating costs and high energy savings. Moreover, with air lubrication, an 80% reduction in the drag of the flat plate was achieved by Merkle et al. (1983) and Madavan et al. (1984, 1985).
Calculation Method of Intermediate Bearing Displacement Value for Multisupported Shafting Based on Neural Network
Authors: Yibin Deng , Xiaogang Yang , Yanling Huang , Tian Pan , Hanhua Zhu
Published: January 2021

The mutual influence between the bearings of a ship’s multisupport shafting makes its installation and alignment very difficult. This article addresses the problem of the calculation of the precise displacement value of each intermediate bearing and proposes a method for fitting the shafting characteristic function by using the GA-BP (genetic algorithm-back propagation) neural network. The neural network uses the intermediate bearing reaction as input to calculate the theoretical height of the bearing, thereby accurately calculating the displacement value. Taking the installation and alignment of a ro-ro ship’s propulsion shafting as an application example, a neural network of the ship’s shafting is established with training samples based on finite element simulation, and the effect of network training is discussed. The accuracy of the method is verified by a comparative analysis with the measured data of the ship’s shafting. The calculation results of this method are used as a guide for the installation and alignment of the ship’s shafting and have passed the delivery inspection of the classification society.

Introduction

The main function of propulsion shafting is transferring power from the main engine and driving propeller rotation for ships and, at same time, transmitting the thrust and tension produced by the propeller to the hull through the thrust bearing (Korczewski 2017; Lai et al. 2018a). A large number of studies have shown that good shaft alignment can reasonably distribute the bearing reaction on each bearing (Kim et al. 2017; Ko et al. 2017; Dong et al. 2018; Lee et al. 2019), which is an important guarantee for the stable navigation of the ship. Improper alignment will result in excessive load on the individual bearing and abnormal wear, which will affect the safe, reliable and stable operation of a ship seriously and increase abnormal vibration (Zou et al. 2016; Guo et al. 2018) and noise (Huang et al. 2014) as well. Therefore, the classification societies have formulated relevant regulations for the magnitude of the bearing reaction during shafting installation. However, shafting of large ships is relatively long and usually adopts multiple intermediate bearing supports. Because of the lack of a certain height reference in the ship and the mutual coupling of intermediate bearings during shafting installation, shafting alignment is very difficult.
Numerical Simulation of Green Water on Deck with a Hybrid Eulerian-Lagrangian Method
Authors: Liao Kangping , Duan Wenyang , Ma Qingwei , Ma Shan , Yang Jianming
Published: January 2021

Green water on the ship deck in rough sea conditions may induce extreme impulsive wave impacts on superstructures and result in severe structural damage. It is of great importance to consider green water loads in ship structure design. However, there are many challenges in predicting green water loads due to the strongly nonlinear wave–ship interactions and the multiphase, multi-scale nature of the wave impact phenomena. In this article, a three-dimensional hybrid Eulerian–Lagrangian approach is proposed for simulating green water loads on the ship deck. It is extended from an efficient and accurate two-dimensional method developed for fluid–structure interaction problems. In this method, the flow field is solved on a fixed regular Cartesian grid system in an Eulerian framework, whereas the solid body motion is tracked with a set of markers immersed in the fluid and solved in a Lagrangian framework. Two benchmark cases, green water on a fixed simplified Floating Production Storage and Offloading (FPSO) model and green water on ship, are simulated. Comparison between experimental data and numerical results shows that our method is a viable choice for predicting green water loads.

Introduction

In rough sea conditions, ships may undergo large-amplitude motions and suffer green water impacts due to the strongly nonlinear wave–body interaction. Large waves run up to the ship deck and impact on superstructures with huge volume of water impulsively. It can induce extreme impulsive wave impact loads on superstructures and result in severe structural damage. Thus, it is important to predict wave impact loads for ship structure design. However, there are still great challenges in predicting green water impact loads accurately because it is a flow phenomenon of high complexity and randomness due to its multiphase, highly turbulent nature with wave breaking, air entrainment, etc (Temarel et al. 2016).
Probability of Sea Condition for Ship Strength, Stability, and Motion Studies
Authors: Perrault Douglas Edward
Published: January 2021

Modeling and simulation continues to be an important tool for determining the response of sea-going vessels to wind and waves. To provide appropriate forcing functions to the models, it is important to have environmental data of sufficient fidelity to facilitate an assessment of platform response, which is as accurate as possible within the practical constraints of time and resources. Fortunately, there are a variety of sources of good wave data, including the U.S. National Oceanic and Atmospheric Administration. This study examines the wave data in the context of simulation codes for assessing characteristics of ocean craft response. It also looks at some practical considerations to limit the scope of simulations. The work is strongly influenced by modeling and simulation of naval surface ships, looking for extreme behaviors, but many of the issues discussed are broadly applicable to other applications.

Copyright 2021 Her Majesty the Queen in Right of Canada, Department of National Defence
A Dissipative Green’s Function Approach to Modeling Gravity Waves behind Submerged Bodies
Authors: Fürth Mirjam , Tan Mingyi , Chen Zhi-Min , Arai Makoto
Published: January 2021

Potential flow-based methods are common in early design stages because of their associated speed and relative simplicity. By separating the resistance components of a ship into viscous and wave resistance, an inviscid method such as potential flow can be used for wave resistance determination. However, gravity waves are affected by viscosity and decay with time and distance. It has, therefore, long been assumed that the inclusion of a damping parameter in potential flow would better model the wave resistance. This article presents a Kelvin-Neumann dissipative potential flow model. A Rayleigh damping term is inserted into the Navier-Stokes equations to capture the decay of waves. A new 3D Green’s function based on the Havelock-Lunde formulation is derived by the use of a Fourier transform. An upper limit for the Rayleigh damping term is found by comparison with experiments and a possible improvement on conventional potential flow models for the wave making resistance prediction of a submerged ellipsoid is proposed.
Ship Hull Resistance Prediction from Model Tests with a Resistance Similitude Simulator
Authors: Shen Young T. , Hughes Michael J.
Published: January 2021

Depending on model sizes and test speeds, model Reynolds numbers are typically one to two orders of magnitude less than those occurring at full scale. The region of laminar flow is significantly larger on a model surface than at full scale. Turbulence stimulators (TSs) are extensively applied in model resistance tests to simulate ship boundary layer flow. Because of lack of theoretical guidance, the size, shape, and location of turbulent stimulators used in each test facility are typically selected based on experience gained in each laboratory, and parasitic drag induced by TSs is subtracted from measured model resistance in some test facilities and not subtracted in other facilities. If turbulence stimulation can be specified in such a way as to achieve momentum thickness similarity between the model and full scale, the form factor will be constant, so a simple scaling formula can be applied to predict ship resistance. Ship resistance can be predicted from measured model resistance with the application of this simple scaling formula. The article describes how for a given body geometry, ship Reynolds number and model Reynolds number, a unique TS (size, shape, and location) can be designed based on three equations derived in this article. This uniquely designed TS is termed the "resistance similitude simulator" in this article. The parasitic drag induced by the simulator is a part of the similarity solution and does not need to be subtracted from measured model resistance.

1. Introduction

The ability to predict resistance plays an important role in the design of a ship or submarine. An accurate prediction of the drag of the vessel is required for the propulsor design and to determine the required power. The resistance of the vessel also strongly influences its lifetime operation costs. Although computational methods are now commonly used to estimate ship resistance, model tests are still heavily relied on, and scaling formulae are used to relate model data to full-scale performance.
CFD Simulations of Self-Propulsion and Turning Circle Maneuver up to 90º of Ship in Waves
Authors: Liu Cong , Wang Jianhua , Wan Decheng
Published: January 2021

In the present work, a Reynolds-Averaged Navier-Stokes (RANS)-overset method is used to numerically investigate self-propulsion and turning circle maneuver in waves for a container ship. A computational fluid dynamics (CFD) solver naoe-FOAM-SJTU is used for the numerical computations of the fully appended Duisburg Test Case ship model. Overset grids are used to handle the motions of the ship hull appended with the propeller and the rudder. Open source toolbox waves2Foam is used to prevent wave reflection in the computational domain. The current numerical method is validated by comparing the ship speed in the self-propulsion case between CFD and Experimental Fluid Dynamics (EFD). Predicted ship 6-DOF motions, hydrodynamic forces, free surfaces, and inflow of the propeller are presented. The propulsion characteristic is mainly studied. Assuming the thrust identification method works even in unsteady conditions, the wake fraction and propulsion efficiency are discussed. The effect of orbital motion of water particle and ship motion on the propulsion performance are identified. In conclusion, the present RANS-overset method is a reliable approach to directly simulate self-propulsion and turning circle maneuver in waves.
Prediction of Residual Stress on Cold-Formed Curvature Plates by Elastoplastic Material Model
Authors: Lin Yue , Shen Wei , Song Lifei , Liu Enqian
Published: January 2021

To meet the demand of automatic production, the multisquare punch forming has been improved to process complex curved plates. However, the improved forming equipment improves the processing quality to the maximum extent, and springback and residual stresses are inevitable phenomena in the cold bending process. Residual stress is an important factor that causes fatigue crack and stress corrosion crack. And the residual stress in machining will seriously affect the fatigue life of cold-pressed parts. Therefore, it is necessary to quantitatively and qualitatively analyze the residual stress caused by the cold forming equipment. Through theoretical derivation and finite element simulation methods, the residual stress distribution for thick plates in the cold forming process was analyzed and compared in this article. Meanwhile, the variation law of residual stress peak with thickness and forming radius was further discussed. The results show that the residual stress distributions obtained by the two theoretical models are in good agreement with the numerical results. The maximum error of peak residual stress is about 10%, which verifies the reliability of theoretical formulas.

1. Introduction

A large number of complex curved sheet metal parts are used in aerospace, marine structure, automobile, and other manufacturing industries, which makes the processing and forming of complex curved sheet metal parts attract much attention. In the process of ship construction, the forming and processing of hull plates is an important part of the low intelligence, time-consuming, and serious constraint on shipbuilding automation. Strictly speaking, most of the parts in the hull plate are three-dimensional curved surfaces, most of which are composed of complex undevelopable spatial curved surfaces. It is a very difficult and urgent key technology to process a ship's steel plate into complex three-dimensional curved surface shapes. such as saddle shape or sailed shape (see Fig. 1A), to create a streamlined outer body of the ship. For many years, bending of plates with complex curvatures has been carried out by manual operation, i.e., the combination of heat line forming and rolling bending (see Fig. 1B). However, the production efficiency of the thermoforming process is relatively low, and environmental pollution is relatively serious with bad working conditions and high labor intensity. Moreover, the forming quality depends more on the experience of technicians, and quality cannot be guaranteed. With the increasing demand for automation, the multipoint forming equipment was developed and used for stamping and forming of curved plates.
Turbulent Skin Friction Reduction through the Application of Superhydrophobic Coatings to a Towed Submerged SUBOFF Body
Authors: Gose James W. , Golovin Kevin , Boban Mathew , Tobelmann Brian , Callison Elizabeth , Barros Julio , Schultz Michael P. , Tuteja Anish , Perlin Marc , Ceccio Steven L.
Published: January 2021

In the present study, the drag-reducing effect of sprayed superhydrophobic surfaces (SHSs) is determined for two external turbulent boundary layer (TBL) flows. We infer the modification of skin friction created beneath TBLs using near-wall laser Doppler velocity measurements for a series of tailored SHSs. Measurements of the near-wall Reynolds stresses were used to infer reduction in skin friction between 8%and 36%in the channel flow. The best candidate SHS was then selected for application on a towed submersible body with a SUBOFF profile. The SHS was applied to roughly 60% of the model surface over the parallel midbody of the model. The measurements of the towed resistance showed an average decrease in the overall resistance from 2% to 12% depending on the speed and depth of the towed model, which suggests a SHS friction drag reduction of 4–24% with the application of the SHS on the model. The towed model results are consistent with the expected drag reduction inferred from the measurements of a near-zero pressure gradient TBL channel flow.

Introduction

Nature has provided a plethora of materials to be studied and mimicked for everyday applications (Jung & Bhushan 2010). One material pertinent for use in the marine environment is the lotus leaf, which is known for its self-cleansing properties and resistance to wetting (Neinhuis & Barthlott 1997). More specifically, lotus-inspired superhydrophobic surfaces (SHSs) have been biomimetically developed for skin friction reduction in various flow applications (Bhushan et al. 2009; Samaha et al. 2012). Being exhaustively studied in small-scale laminar flows (see Rothstein [2010] for a review of SHS drag reduction and slip on SHSs), advances in the design and fabrication of SHSs have permitted application of these materials in more naval-relevant flows. Previously, it has been shown that in laminar flow, SHSs can reduce drag (Watanabe et al. 1999; Ou et al. 2004; Ou & Rothstein 2005; Zhao et al. 2007; Daniello et al. 2009; Woolford et al. 2009), and in low–Reynolds number turbulent flows, SHS drag reduction has been observed using small-scale, structured surfaces and large air–water interfaces (Henoch et al. 2006; Daniello et al. 2009; Park et al. 2014). However, these surfaces, in higher turbulence flows, can be unstable or become wetted. If the SHS possesses roughness features with small scales compared with the viscous length scale of the flow, researchers have demonstrated SHS friction drag reduction for wall-bounded, high–Reynolds number turbulent flows (Zhao et al. 2007; Aljallis et al. 2013; Bidkar et al. 2014; Golovin et al. 2016; Ling et al. 2016b; Gose et al. 2018a).
Effects of Hull and Control Surface Roughness on Ship Maneuvering
Authors: Daidola John C.
Published: January 2021

The effects of hull roughness on ship maneuvering characteristics are investigated. The hydrodynamic derivatives in the equations of motion for surface vessel maneuvering are modified to incorporate roughness of the hull and rudder. Vessel lifetime roughness profiles are postulated based on construction, coatings, operation, and maintenance for a vessel life of 25 years. These are then applied to the turning maneuver for single screw cargo ships with block coefficients from .60 to .80. The implications for naval missions are discussed.

Introduction

The effects of hull roughness, including fouling, are known to affect the performance of a vessel, especially as measured in additional fuel consumption and less so, the number of voyages in a lifetime. Today, there is significant attention given to hull surface cleaning, coating, and propeller polishing to address these issues. In addition and even less known are the effects on the maneuvering performance of a vessel. For naval vessels, they may affect the success of the mission.

Roughness of the hull can occur because of a number of factors including hull material used and quality of construction, mechanical damage in operation, roughness from paints and coatings and their method of application, damage to the coating during maintenance, corrosion and pitting of the hull structure material, and biofouling influenced by the type of antifouling paint or coating and method of application. The roughness never ceases to increase during the vessel’s life. Starting with the hull material and construction, then the effects of different paints and coatings, operations, dry-docking intervals, and approach to maintenance, it is possible to develop a lifetime roughness profile.
On the Selection of Optimal Propeller Diameter for a 120-m Cargo Vessel
Authors: Andersson Jennie , Gustafsson Robert , Eslamdoost Arash , Bensow Rickard E.
Published: January 2021

In the preliminary design of a propulsion unit, the selection of propeller diameter is most commonly based on open water tests of systematic propeller series. The optimum diameter obtained from the propeller series data is, however, not considered to be representative for the operating conditions behind the ship, instead a slightly smaller diameter is often selected. We have used computational fluid dynamics to study a 120-m cargo vessel with an integrated rudder bulb-propeller hubcap system and a four-bladed propeller series, to increase our understanding of the hydrodynamic effects influencing the optimum. The results indicate that a 3-4% smaller diameter is optimal in behind conditions in relation to open water conditions at the same scale factor. The reason is that smaller, higher loaded propellers perform better together with a rudder system. This requires that the gain in transverse kinetic energy losses thanks to the rudder overcomes the increase in viscous losses in the complete propulsion system.
The History of Modern Shipbuilding Methods: The U.S.-Japan Interchange
Authors: Chirillo L. D. , Chirillo R. D.
Published: January 2021

This paper was given as testimony during a 20 June 1984 hearing by the House Merchant Marine Subcommittee. Thus, the entire paper is part of the Congressional Record. The testimony relates a concise history of modern shipbuilding methods, a brief description of those methods, and prerequisites for modern shipbuilding to take hold in the United States.
The Productivity Problem in U.S. Shipbuilding
Authors: Weiers Bruce J.
Published: January 2021

U.S. shipbuilding productivity is significantly less than that of Japan and some European countries. The traditional view has either minimized the importance of the difference in productivity between U.S. and the best foreign shipyards, or focused on the lack of opportunities for U.S. yards to build in long series. As a result of research since 1977—much of it conducted under the auspices of the Maritime Administration National Shipbuilding Research Program—a new view of the productivity difference has developed. Several studies have established that the productivity difference is very large. A number of studies have related this difference to new methods and systems of shipbuilding developed abroad. Based on a review of the literature, this study describes these methods and systems and examines obstacles to their adoption in the United States. Implications for public policy are discussed. Some current efforts of U.S. shipbuilders to improve productivity and Maritime Administration and Navy programs of technology promotion are referenced.
Accuracy Control Variation-Merging Equations: A Case Study of Their Application in U.S. Shipyards
Authors: Storch Richard Lee
Published: January 2021

As a part of the ongoing move by many U.S. shipyards to adopt zone-oriented ship production, the need for an accuracy control system has been identified. Recent research has indicated that the accuracy control system can form the basis for performing process analyses as a means of improving productivity. This paper reports the results of Maritime Administration-sponsored research to develop a set of variation-merging equations for a specific vessel construction project. The equations are presented for the stern section (block 6) of the U.S. Navy T-AGOS ocean surveillance vessels under construction at Tacoma Boatbuilding Company. Data collected in 1982 provided process means and standard deviations for the following stages of production: part fabrication, panel line, subassembly and subblock assembly. Based on these data and observed assembly sequences, variation-merging equations are written and analyzed for the assembly of subblocks 602 and 603 and for the assembly of block 6 (that is, joining of 602 and 603). The impact on the merged variation of altering the assembly sequence is also analyzed and reported. The analysis is used to predict rework type (gas cutting or back-strip welding), and probabilities. Although these equations are dependent on the shipyard and the design, the techniques and principles for their development are applicable for any shipyard and any design. As such, they form a case study which makes them suitable as a guide for shipyards undertaking analysis of assembly procedures using variation-merging equations.
Criteria for Capacity Certification of Dry Docks and Significance of Classification and U.S. Navy Standards as They Affect Ship Safety
Authors: Crandall Paul S.
Published: January 2021

Extremely expensive and sensitive warships as well as valuable merchant ships are being docked in a wide variety of dry docks, many of them not originally built for the modern vessels and often operated by crews with very rudimentary training and experience and with limited engineering backup. Only since 1973 has Lloyd's Register of Shipping had published rules for steel floating dry docks, and the ABS rules were created only very recently. Following the example of the 5th Naval District, NAVSEA in Washington started the MIL-STD-1625 code using very limited personnel and funds to prepare a dry dock certification program to attempt to insure ship safety in all docks. It is a serious mistake to think that certification is a cure-all. Adequate qualification of the docking crew is just as important, including skill in dealing with special problems with special ships.
Interim Products—An Essential Innovation in Shipyards
Authors: Chirillo Louis D.
Published: January 2021

Ships of the same kind built in series are not a panacea for lagging productivity. The solution is more fundamental and imaginative. The solution involves a rethinking of an entire shipbuilding system. The world's most productive shipbuilders employ "standard" series interim products made possible by a production system that classifies parts, subassemblies, and assemblies by the problems inherent in their manufacture. The result is highly rationalized design modules and highly organized work. Such interim products are flexible enough to be parts of many sizes and types of ships. Runs of such interim products, not ships, is the key! Research managed and cost-shared by the Los Angeles Division of Todd Pacific Shipyards Corp. for the Maritime Administration created National Shipbuilding Research Program (NSRP) has motivated the current revolution in U.S. shipbuilding methods even for building warships. Guidance was provided by Panel SP-2 of the Ship Production Committee of The Society of Naval Architects and Marine Engineers.
Impact of Technological Change on Shipbuilding Productivity
Authors: Frankel Ernst G.
Published: January 2021

Technological change has resulted in major productivity gains in some shipbuilding countries, while others such as the United States have lagged behind, although a large proportion of these technological changes originated in the United States. In this paper, we evaluate the gains from the factors which play a role in assuring significant productivity gains from technological changes in shipbuilding production processes, and evaluate the effect of industry participation in research and development of process and product technology, the timing of application of new process technology, and the influence of worker incentives and training on the attainment of significant productivity gains through technological change.
Comments on “The History of Modern Shipbuilding Methods: The U.S.-Japan Interchange” and “The Productivity Problem in U.S. Shipbuilding”
Authors: Mack-Forlist D. M.
Published: January 2021

Comparisons of technology and productivity between U.S. and Japanese shipyards are made in two papers in the first issue of the Journal.23 Such comparisons are very difficult and, to some extent, questionable because of the differences in ships and in cost-keeping practices. They are complicated further by the intervention of governments in shipyard operations. In any case, the comparisons show that equalling foreign productivity would not make U.S. shipyards cost-competitive. A coherent government policy implemented by coordinated action is necessary to ensure the operating stability which is essential for productivity and innovation. This was shown by the U.S. wartime program. Clear aims and policies and coordination by government and industry—the entire industry, not led by any one organization or individual, such as Kaiser—produced both extraordinary output and innovation. Many new technologies can only be applied successfully in long-run stable programs which make the productivity gains from both innovation and series production possible.
Improving Shipyard Productivity Through the Combined Use of Process Engineering and Industrial Engineering Methods Analyses Techniques
Authors: Cauthen Tommy L.
Published: January 2021

Despite the obvious compromises to efficiency that must be made when producing small quantities, the shipbuilding industry sometimes rules out or fails to consider some of the efficient techniques and methodologies of mass production manufacturing. In this paper a comparison and contrast is made between the methods of mass production and small quantity manufacturing. Also revealed in this paper are the benefits from the use of a mass production process engineering technique and a methods analysis technique during the performance of the National Shipbuilding Research Program SP-8 Panel Task ES-8-21. The use of a mass production process engineering technique is explained as a solution to a methods problem of excessive travel for tools in shipyard equipment installation by outside machinists. The paper concludes with a promotion of this specific application of mass production methodology in shipbuilding and a promotion of the re-evaluation of mass production techniques by shipyards as a vehicle for productivity improvement.
World Shipbuilding Capacity and Utilization: How Do European Shipyards Fit into the Pattern?
Authors: Sverdrup Cato Fredrik
Published: January 2021

In recent years the supply of merchant ships of practically all classes has outstripped the available cargo for them, leading to a severe slump in shipbuilding orders worldwide. This paper examines current fleet utilization and the prospects for European yards against a background of slow growth in seaborne trade and stiff competition from Japanese, Korean, and emerging third world shipbuilders.
Note on Post-Welded Hull Plate Load-Displacement Behavior
Authors: Latorre R. , Birman V.
Published: January 2021

Initial imperfections occur during the ship production process as a result, primarily, of welding and forming. In some cases these imperfections can change significantly the compressive strength of the ship hull plates. To determine whether this will occur or not requires knowledge of the hull plate load-deflection behavior as well as the plate yield conditions. This paper presents a linear analysis of the load-deflection response for plates with different aspect and slenderness ratios. It is shown that for plates with an aspect ratio less than 2.45, the relationship can be determined. It is recommended that additional field measurements be made to clarify the shape of the post-welded deformation of larger-aspect-ratio plates.
Shipyard Organization and Management Development
Authors: Chirillo R. D. , Inuki I. , Kobayashi I.
Published: January 2021

The philosophy and merits of the two major forms of company management and organizational structure are examined, with particular application to the shipbuilding industry. The highly successful operation of one of Japan s major shipbuilders, a product form of organization, is discussed along with a management strategy that emphasizes hands-on shop experience for all college-educated middle managers. Appendices list examples of typical responsibilities for staff personnel at the yard. Only America can surpass Japan in shipbuilding. But, we do not worry because America has a human problem: not enough college-educated people in middle management. Hisashi Shinto3
High Strength Low Alloy Steels in Naval Construction
Authors: Montemarano T. W. , Sack B. P. , Gudas J. P. , Vassilaros M. G. , Vanderveldt H. H.
Published: January 2021

The Naval Sea Systems Command has recently certified a lower-cost alternative steel to the HY-80 steel presently used in construction of naval surface ships. This alternative steel is based on the commercial development of high strength low alloy (HSLA) steels originally directed to the offshore oil exploration platform and gas line transmission industries. The certification is a result of an ongoing research and development program begun in 1980. This paper addresses several aspects of the HSLA steel development effort, including a discussion of the properties and metallurgy of this steel, and the cost savings which are achievable. Finally, the status of the current and planned Navy HSLA usage and the R&D program is described.
Marine Industry Standards of the U.S. and the World
Authors: Toth Robert B.
Published: January 2021

This paper provides an overview of standards developed or invoked by national and international organizations for the marine industry. Data on standards promulgated by U.S. voluntary and government organizations are presented and compared with those standards available to shipbuilders in other nations. The sources of international and national mandatory standards are reviewed and the U.S. standards system is compared with those of other nations. A critical deficiency in the United States is the relatively small number of fully definitive voluntary standards that can be used for competitive procurement. Recommended action by the marine industry and the standardization community is presented, focusing on the need to effectively apply the limited resources that are available.
The Naval Ship Design/Production Interface
Authors: Tibbitts B. F. , Gale P. A.
Published: January 2021

The paper discusses, from a ship designer's perspective, some of the current topics and issues relating to the interface between naval ship design and production. The current environment within which naval ship design activity is taking place is described. Notable current views on Navy ship design and how it might be improved are summarized. Navy design topics pertinent to improving ship producibility, operability, maintainability and survivability are discussed and examples from recent ship designs are. presented. Issues which result from apparent conflicts in current design initiatives and critiques of the Navy ship design process are highlighted and discussed. Finally, some general conclusions are drawn.
Benefits of the National Shipbuilding Research Program to the Navy and the Industrial Base: Part 1—Maritime Perspective
Authors: Rinehart V. W.
Published: January 2021

This paper traces the development of the National Shipbuilding Research Program (NSRP) from its beginning in the early 1970's to the present time. The goals sought, the approach used, and the organization established to achieve the goals are described. An overview of technical accomplishments is followed by a discussion of two nontechnical areas, namely, organizational support and market development, and the role of the NSRP in these areas. The paper concludes by pointing to the need for reorienting the program as the shipbuilding market changes emphasis, say, from new construction to repair and refit. The changing role of Government is also briefly addressed.