bluuebunny/crossref_metadata_2025 huggingface dataset:
Basic aspects of rural social infrastructure development
Authors: Yarkova Mikhailovna
Published: January 2021

The social infrastructure of rural areas is of particular importance when considering issues of both an economic and social nature. Both production and non-production rural areas necessitate the availability of social facilities. The main purpose of social infrastructure facilities nowadays and in the past of rural and urban areas development is to meet the needs of the population. At the same time, social infrastructure defines the basis for the level and quality of life of civil society. Its condition is an indicator of the territorial development and provides opportunities for innovative development and investment attraction. For many years now, the rural social infrastructure has been in poor condition in Russia. Problems are observed in the living conditions of citizens, in elements of residential properties improvement, undeveloped system of medical and educational services, unavailability of cultural and leisure facilities, and so on. Due to such a negative state of the rural social sphere, problems arise with the demographic situation and the production sphere in terms of the inability to attract highly qualified personnel. The Program for the Sustainable Development of Rural Territories developed by the Government of Russia holds back the general, intensively negative situation, and is fundamentally changing it in some regions of the country. The paper presents the results of the implementation of the main Program directions and gives some recommendations on its further implementation and development of the rural social infrastructure.
The importance of the quality of the agricultural product for sustainable success of agricultural holding
Authors: Milanović Mirko , Nikitović Zorana , Vujičić Slađana
Published: January 2021

Small farms, which are mostly owned by natural persons, characterize the agricultural sector of Serbia. In order for a family farm business or holding to be successful, the following factors can be distinguished: the yield and quality of the products achieved, the prices generated for the products, and, of course, the decisions that are made in order to make the management of the farm more efficient. Given that consumers of agricultural products around the world are demanding increasing product quality, farms should work to improve competitiveness based on quality. The subject of this paper is the importance of the quality of the products for the sustainable success of agricultural holdings in the Republic of Serbia. The main goal of this paper is to provide new knowledge in the field of quality of agricultural products of agricultural holdings with the aim of achieving sustainable success.
Implementation of socially responsible business transactions in trading companies
Authors: Mrvica-Mađarac Sandra , Nedović Mirjana , Galić Matej
Published: January 2021

Trade companies are becoming aware of their role in society and the local community. Socially responsible business transaction means a positive approach to the relationship with the community, its problems and events. It has become recognized among the customers and the company's management. Companies have carried out volunteering and various humanitarian activities to engage themselves in social activities and to increase their reputation towards their customers, suppliers and employees. Factors that have influenced to the development of socially responsible business transactions are: globalization, the transition to a knowledge society, consumer care, civil society activities, environmental problems and other. Trading companies that operate in line with the concept of socially responsible business transactions, when they implement this type of business, they can achieve a numerous benefit, from strengthening of the corporate image, and from competitiveness to the environmental awareness. Socially responsible business transaction also maintains cooperation between businesses, civil society and public administration and as such creates a positive image of social responsibility and contributes to the development of the local community. For the purpose of this paper a research was conducted on a representative sample of trading companies with the aim of gaining insight whether such companies do promote socially responsible business transactions and what kind of activities in such form these companies use.
Possible interactions with mathematically gifted students: Views of prospective teachers
Authors: Yazgan-Sağ Gönül
Published: January 2021

Teachers' interactions with mathematically gifted students in the classroom environment, and the elements of this interaction have become prominent recently. This qualitative study's purpose is to reveal the views of prospective secondary mathematics teachers about these interactions. The study participants were seven prospective teachers attending the fourth year of a secondary mathematics teaching programme in a public university in Turkey during the 2018-2019 academic year. These prospective teachers participated in a 90-minute focus group interview which was recorded with a video camera. During the interview, the researcher brought up possible classroom environment scenarios that could occur with mathematically gifted students who may have the characteristics that the participants described. The prospective teachers' views about the kinds of behaviours they can exhibit, and what methods they can reveal in these theoretical interactions were analysed with the descriptive analysis method. The study results indicated that the participants exhibited different approaches to situations they might encounter in the classroom. For example, some prospective mathematics teachers asserted that mathematically gifted students should be assisted in the classroom context; others stated that such students should be supported with out-of-class activities rather than helping them in the classroom. Besides, the participants suggested that the history of mathematics and advanced mathematics subjects could also be used to educate mathematically gifted students.
Burnout experience of secondary and preparatory school teachers in West Gojjam and Awi zone in Amhara regional state
Authors: Wulolign Anteneh , Adane Solomon , Kassie Solomon
Published: January 2021

The purpose of the study was to assess Burnout experience of secondary and preparatory school teachers in West Gojjam and Awi Zones in Amhara regional state. Participants of the study were selected by simple random sampling technique. The study employed cross-sectional survey design method to answer the proposed research objectives regarding burnout experience by secondary school and preparatory school teachers. The primary data collection tool for the study was questionnaire. The level of burnout was assessed using standardized questionnaire, and these standardized questionnaires were adopted from the original English version Maslch burnout inventory Human service Survey to assess the level of burnout. The descriptive statistics on the mean scores of the three dimensions of burnout indicated that teachers were experiencing high levels of burnout in all the three dimensions of burnout. The independent samples t-test result showed that there were no statistically significant differences between the two groups (male and female) in EE and PA burnout levels (t= 1.35, df = 286, p =.176 >.05) and (t= -1.007, df = 286, p =.315 >.05).
Knowledge mapping on temperament in early childhood: A visualized analysis using Cite Space
Authors: Yurtçu Meltem , Pekdogan Serpil
Published: January 2021

In this study, the social network structure of the studies conducted in the early childhood towards the concept of temperament was examined. The research was considered as a descriptive study since it examined the relation between the existing studies according to the citations. The concept of temperament in early childhood has taken its place in the literature as a concept that began to be studied in 1955. 1025 studies on this subject in the Web of Science database were examined. Studies conducted between 1975-2020 were analyzed. In this study, Cite Space program, one of the social network analysis programs, was used. Documents were examined in relation to co-citations by authors, journals, countries and sources. As a result of the examinations, it was concluded that the most cited country was the United States, the most cited author Mary K. Rothbart, and the most cited journal Child Development. As a result of examining the co-references in the documents, 18 clusters named using the LLR (log-likelihood) algorithm were obtained. The names of the clusters and the most cited articles were determined in accordance with the network structure. At the same time, it is possible to see which clusters are more active in which periods and when the co-citations are analyzed according to the references and which articles are referred to more frequently. The current studies on this subject have been included in child obesity risk, postnatal plasticity revisited and extended and dispositional negativity clusters. With the results of this research, a map of information is presented to the researchers who want to study on the subject of temperament in early childhood. It can direct the researchers according to their sub-fields. It gives information about important sources, authors, and journals about the subject of interest, according to the tendency of the researcher. In addition, the researcher could see current issues or what topics the literature lacks. Therefore, as with this topic, authors can obtain detailed information about the subject area with such bibliometric studies while choosing the field of study.
Attitudes of Turkish secondary school teachers towards technology
Authors: Ersoy Mustafa , Kavaklioglu Orhan
Published: January 2021

This study aims to evaluate secondary school teachers' attitudes towards technology in terms of various variables. The study attempts to reveal attitudes of teachers towards technology and influence of some variables like gender, self-efficacy, branch, in-service training and the level of education. Technology is becoming more widespread and important in education. The Ministry of National Education (MEB) started the Movement to Increase Opportunities and Technology (FATIH) project. FATIH project is one of the most comprehensive projects developed around the world in order to benefit from technological developments and to have a contemporary human resource. When the studies done in the field of education and technology are examined, it can be seen that they are generally focused on adaptation of technology and students' perspectives. However, a change without teachers is not possible even with technological developments. Thus, attitudes and approaches of secondary school teachers towards technology are gaining importance since students see teachers as their role models in their most critical period of development. For this reason, it is important to evaluate secondary school teachers' attitudes towards technology in terms of some variables. In this study, the general survey model was used. The population of the study was secondary school teachers working in Sivas during the 2017-2018 academic year. The sample of the study consisted of 200 secondary school teachers and they were selected randomly. In this study, the Scale for Pre-Service Teachers' Attitudes towards Technology, developed by Aydın and Karaa (2013) and consisting of 17 items, and Personal Information Form (PIF), developed by the researcher himself by consulting expert opinions, have been used to collect data. SPSS 25 package program has been used in the analysis of the data. Arithmetic mean, t-test and ANOVA analysis methods have been carried out in the analysis of the data.
New tendencies in the development of environmental movements in the 21st century
Authors: Nadić Darko
Published: January 2021

Environmental movements are continuing to demonstrate their relevance and innovative tendencies in the 21st century. Environmental problems are as yet unresolved in this century, the global environmental crisis exists, but the policies of green parties, which arose from environmental movements, have not yielded adequate results. The paper presents the origins of environmental movements as well as their separation from new social movements. In the context of this separation, the paper explores the stages of development of environmental movements from their inception to the present day and compares the activities of these movements, from protest to pacification and marginalization, through "corporate" eco-movements, to the creation of so-called communal eco communities which could figure as environmental movements in the future. Based on the development of environmental movements so far, their future in this century is considered, as well as new tendencies and trends. In this sense, the subject of analysis are movements such as the "Economy for the Common Good", which aims at not only environmental but also complete social transformation, and current and ad hoc movements such as "Extinction Rebellion" and "Fridays for Future". Special emphasis is placed on offshoots, such as "influencer ecologism", "celebrity ecologism" and "tabloid ecologism", that are presented as initiatives that could possibly create environmental movements in the future.
Contributions of American theoretical thought to the disciplinary constitution of contemporary international relations
Authors: Despotović Ljubiša
Published: January 2021

This paper will articulate and argumentatively prove the crucial contribution of American theoretical thought to the disciplinary constitution of contemporary international relations as a discipline in political science. In particular, we will consider three important directions of theoretical research of international relations - historical, systematic and normative. We will pay special attention to the liberal and realistic school of thought and its most important theoretical insights concerning the character of international relations, especially after the Second World War.
Waste treatment in the Republic of Serbia
Authors: Todorović Mirjana
Published: January 2021

Waste management is a universal topic that applies to every living being on the planet. Decision makers create policies that affect everyday issues such as health, cleanliness, food and water, the environment in which we live. Poor waste management leads to the contamination of rivers, soil, air, and thus leads to infections, respiratory infections, cancer, heart and blood vessel diseases, and causes harm to animals that consume waste substances. Poor waste management also affects the economy, the exploitation of natural raw materials, tourism. For these reasons, it is necessary to initiate urgent actions and increase the awareness of individuals and society as a whole through education and understanding. Inadequately disposed of waste creates emissions of greenhouse gases. Also emitted into the atmosphere are hexavalent chlorine, polychlorinated biphenyls, dioxins, furans, powdered substances and thousands of other chemicals that are carcinogenic, teratogenic and mutagenic. Industrial waste management requires much more engagement because such waste also contains more substances that negatively affect the environment. Therefore, a thorough analysis of the amount of waste generated in Serbia and the capacities of the country to treat this waste is necessary. Also needed are changes in legislation which would benefit both citizens and industry, the strengthening of administrative capacities within the waste management system and information sharing.
Development and main directions of Hungary's foreign policy since 1990
Authors: Pinter Atila
Published: January 2021

This paper explores the three key priorities of Hungarian foreign policy after 1990: Euro-Atlantic integration, regional relations and relations with Hungarians living outside the borders of what is today Hungary. Also presented is a brief overview of recent events in Hungarian-Serbian relations. The paper describes the effects achieved, their political rationale and gives an assessment of the results achieved. The study concludes that Hungary was quickly and successfully integrated within the Euro-Atlantic alliance (NATO, EU), in the process developing new mechanisms for helping Hungarians living in other countries, which was achieved through improved cooperation with its neighbors. There are still areas where relations might be improved and cooperation and historical reconciliation with Serbia can be viewed as an exceptional example of this.
Global compact on migration: Legal nature and potential impact on the development of international migration law
Authors: Krasić Bogdan , Stojanović Bojan
Published: January 2021

International migration, both forced and voluntary, represents a prominent phenomenon in modern society, which is gaining public attention in countries of origin, transit and destination. However, the issue of migration has not been significantly regulated internationally to date, and the pioneering endeavour has taken place with the adoption of the Global Compact for Safe, Orderly and Regular Migration. A major issue that will continue to gain public attention is the future impact of the Global Compact on the formation of the body of international migration law. Although formally not a legally binding document, adoption of the Global Compact was followed by criticism precisely in regard to its potential legally binding force, actual or presumed. For proponents, it represents a starting point for creating adequate migration policies that are consistent with international human rights law, sustainable development, labour market needs and other policies. This study analyses the legal nature of the Global Compact from the soft law perspective as a source of international law and the initial steps in its implementation to determine states' adherence to its provisions and the potential impact on the development of international migration law.
Tito's Concordat: The 1966 protocol on the negotiations between Yugoslavia and the Holy See from a legal perspective
Authors: Božić Marko
Published: January 2021

The paper discusses the 1966 Protocol on the Negotiations Between Yugoslavia and the Holy See that has already been subject to several historical analyses focusing primarily on negotiations leading to it rather than the document itself. The initial hypothesis is that the legal profile of the 1966 Yugoslav Protocol may indicate its hidden political weight and a deeper historical meaning. In order to discern it, the paper examines the Protocol as an instrument of international law, aiming at explaining the way its form and substance have reflected difficulties and affected changes in relations between a Communist state and the Roman Catholic Church in Tito's Yugoslavia. Therefore, the paper compares the 1966 Yugoslav Protocol with its Eastern-European equivalents and discusses its impact on further evolution of the Yugoslav constitutional and legal framework.
The right to peaceful enjoyment of property and the security measure of the forfeiture of cash in the jurisprudence of the Serbian Constitutional Court: Certain uncertainty
Authors: Korhecz Tamás
Published: January 2021

The right to peaceful enjoyment of property is a first-generation human right, protected by the international and domestic law of the highest rank. This is not an absolute right - the European standards of protecting property rights allow possible interferences prescribed by law. The interferences can be made in the public interest but only under the assumption that the proportionality between the public interest and property rights of individuals at stake is established. Forfeiture of undeclared cash the individuals are transferring across state borders, together with imposing fines for a misdemeanor, represent an interference with individuals' property rights. The EU Member States do not share an identical system of sanctions for this petty offense, but there is a tendency of unification related to the monitoring, registering, and sanctioning of undeclared, cross-border, individual cash transfer. The case-law of the European Court of Human Rights has established rather precise criteria for distinguishing permitted from unpermitted interferences in cases of undeclared cross-border cash transfers. The Serbian Constitutional Court has been faced with several constitutional complaints regarding alleged unconstitutionally of the imposed security measure amounting to the forfeiture of undeclared cash physically transferred across the state borders. The Constitutional Court has ruled inconsistently on the matter. Although it has regularly referred to the European Court of Human Rights' relevant decisions, it fails to be consistent in following the Strasbourg Court's rulings. In this article, the author has suggested that the legal certainty principle requires the Constitutional Court to consistently interpret the constitutional rights and be systematic in following Strasbourg. Only in this way, the Constitutional Court can help regular courts effectively to harmonize the interpretation and application of laws with the constitutional and international human rights standards regarding property rights.
Human rights issues in investment arbitration cases: A new perspective?
Authors: Begić-Šarkinović Taida
Published: January 2021

This article addresses recent human rights matters in the context of treaty-based investment arbitration. After having analyzed two recent arbitral awards, Urbaser v. Argentina and Bear Creek v. Peru, the article argues that host states' counterclaims on the basis of human rights can serve as an effective vehicle for rebalancing investors' rights and regulatory powers of host states. Both cases illustrate a more progressive approach of investment arbitral tribunals when dealing with human rights issues. Host states' counterclaims can also provide a door for arbitrating corporate-related human rights violations in the sense that they can ensure the application of international human rights law in investment arbitration cases. International investment promotion for sustainable development requires rebalancing the rights and obligations of states and investors which could help ensure corporate human rights accountability. In this regard, international investment treaties have to be renegotiated in order to include more human rights content targeting investors' human rights conduct and in that way provide a more balanced approach when disputes arise.
Constitutional resistance to EU law: The courts and test of constitutional identity conflicts
Authors: Galimberti Marco , Ninatti Stefania
Published: January 2021

This essay aims to analyze how national constitutional/supreme Courts address the evolution of the European integration process when this latter touches upon fundamental constitutional elements of the EU Member States. More specifically, the paper explores the recent case law concerning the issue of constitutional identity conflicts, in order to show the common arguments underpinning different European constitutional/supreme Courts' jurisprudence. From a comparative point of view, the analysis highlights the emergence of a growing front of constitutional resistance whose meaning for the future of European constitutionalism is still unclear. At the same time, the study seeks to examine the patterns of constitutional resistance within the European integration process in the perspective of a mutual interaction between Courts.
Rebalancing human rights at the time of Covid-19 pandemic
Authors: Sándor Judit
Published: January 2021

The year of 2020 will certainly be in all future books on the history of epidemiology and the Covid-19 pandemic will be discussed in them as perhaps the most significant public health challenge since the Spanish flu. But I also hope that it will feature as a new chapter in the books on health and human rights. The suffering of millions of people around the world, the deaths and medical challenges have already presented many lessons to learn from. One of the lessons should be to recognize the right to health as a full-fledged human and constitutional right that deserves a much closer attention whenever annual budgets are drafted and it should be considered as a fundamental human right without which no other rights can be exercised in epidemiological crises and even after that.
Stacking: Determining the result system of an arbitrary force system with defined attack points
Authors: Šrndić Faruk , Fejzić Jasmin
Published: January 2021

The equilibrium conditions of a system of external forces acting on a rigid body in the scientific discipline of statics are solved by a graphical procedure - construction and analytical procedure - by calculation. The graphical procedure is simpler and more transparent. The technical problems in statics are solved in both procedures and the results should be the same or approximately the same. The accuracy of the results of the graphical procedure using the method III of the force polygons and the III chain polygons presented in this paper is simply verified by cutting the directions of all three results at one point.
Optimal Design of Propulsion System Configuration for Electrically Propelled Unmanned Surface Vehicle
Authors: Xiong Liuqing , Gao Haibo , Norman Rosemary , Pazouki Kayvan , Lin Zhiguo , Lim Serena
Published: January 2021

Unmanned surface vehicles (USVs) are vessels that operate without any crew onboard. There is an increased demand for USVs in recent years, particularly for the use of water quality monitoring and ocean data mapping. In China, USVs are widely used as a luring fish boat which acts as the assisting boat of light luring seine vessel. One of the main problems of such boat is that the traditional propulsion system is poorly matched with the high energy consumption that is required during certain specific operation, which results in poor vessel performance. A hybrid electric propulsion system configuration solution is proposed to increase the overall propulsion efficiency of such USVs. The typical operating profile was identified and a comprehensive simulation was conducted to demonstrate the compatibility during vessel operations. An intelligent equipment selection analysis was also carried out to recommend the optimal equipment selection by considering a multiobjective problem. The result shows that the configuration solution proposed can reduce fuel consumption and the optimal intelligent selection method can provide a suitable selection solution for decision makers. This article highlights an energy management strategy focusing on the threshold method based on support vector machine pattern recognition. A multiobjective particle swarm optimization algorithm based on the dynamic inertia weight and chaotic motion was used to optimize the equipment selection by considering fuel consumption and emissions. The proposed propulsion system configuration and equipment selection solution can be implemented for the design of USVs, which has a routine fixed operating pattern.
Ultimate Strength of Hull Structural Stiffened Plate with Grooving Corrosion Damage under Uniaxial Compression
Authors: Zhu Yufan , Zhang Yan , Du Fei
Published: January 2021

Grooving corrosion results in a decrease in the ability of the structure to resist external loads. In the present study, a new assessment method was developed to investigate the ultimate loading capacity of stiffened plates with grooving corrosion damage. First, the basic parameters of stiffened plates (including model range, boundary condition, welding residual stress, initial geometric imperfection, and size of finite element) were assumed. Second, the influences of corrosion parameters and geometrical parameters of stiffened plates (such as finite element type, groove width, groove depth, groove depth-to-width ratio, plate flexibility, stiffener flexibility, and number of stiffeners) were analyzed. Third, based on the data analysis from a large number of nonlinear finite element analyses, the ultimate strength reduction formula of stiffened plates was derived. Last, the correctness of the formula was verified by ultimate strength experiment.

Introduction

Ships are always in the harsh marine environment, and it would inevitably be corroded. The existence of corrosion would reduce the effective thickness of structures and promote the generation of fatigue cracks, brittle failure, and instability damage. Grooving corrosion is a major corrosion form leading to structural failure of the hull structure (Zhang et al. 2017b). Therefore, it is very important to study the ultimate loading capacity of corroded structures to ensure the safety during the total expected life cycle.

Corrosion mainly included uniform corrosion and local corrosion. Local corrosion (such as pitting corrosion and grooving corrosion) was relatively complex. For local corrosion, complex corrosion status appears on the surface of the hull structure. Sultana et al. (2015) analyzed the effect of random pitting on the ultimate compressive strength of plates and stiffened plates. They found that the volume loss caused by corrosion resulted in a significant reduction in the ultimate strength of plates, up to 45%, compared with stiffened plates. Huang et al. (2017) derived the ultimate strength reduction formula of pitted stiffened plates by analyzing a large number of nonlinear finite element analysis (FEA) data. Woloszyk et al. (2018) studied the effect of severe local corrosion damage on the strength capacity of stiffened panels by combining finite element with experimental. They found that corrosion not only reduces the thickness of the structure but also increases the surface roughness and affects the mechanical properties.
Numerical Investigation on the Added Resistance and Seakeeping Performance of KVLCC2 with the SWENSE Method
Authors: Zhang Yang , Reliquet Gabriel , Bouscasse Benjamin , Gentaz Lionel , Le Touzé David
Published: January 2021

In this study, the added resistance and seakeeping performance of the KVLCC2 ship is investigated by using the spectral wave explicit Navier–Stokes equations (SWENSE) method. The SWENSE method is based on the decomposition of the total field into an incident part explicitly obtained by the wave potential flow theory and a complementary part solved with a modified Reynolds-averaged Navier–Stokes solver. Therefore, the computational efficiency can be achieved by using a relatively coarse mesh in the far field, retaining the accuracy of the incident waves. A parametric study is performed under regular wave conditions with 3Degree of Freedom (DOF) motions of the hull. The results are compared with the large literature available. An additional case is simulated to demonstrate the capability of the present method in simulating seakeeping problems in irregular sea states. Good agreement between the computed results with the reference data can be observed for the hull model, which indicates that the added resistance and seakeeping performances can be well predicted by the present method.

Introduction

In recent years, the Energy Efficiency Design Index (EEDI) has been introduced by the International Maritime Organization to restrict greenhouse gas emissions from ships. In the EEDI formula, the evaluation of the added resistance is required and defined as the increased resistance in the actual sea state due to waves, winds, etc. compared with the resistance in the calm sea condition. The resistance in actual sea states could be up to 30% greater than that in the calm water resistance (Lee et al. 2017). Therefore, prediction of the added resistance induced by waves is an important subject for ship design and is the focus of the present study.
Fatigue Strength Assessment of a Butt-Welded Joint in Ship Structures Based on Time-Domain Strain Approach
Authors: Dong Yan , Garbatov Yordan , Soares Carlos Guedes
Published: January 2021

Fatigue strength assessment of a butt-welded joint in ship structures based on a time-domain strain approach is performed in this study. The service life load histories applied to the butt-welded joint located on the deck of a bulk carrier are generated, accounting for the still-water and wave-induced loads. The rainflow counting method is applied to analyze the load histories, and the long-term distributions of the load range are compared with those based on the conventional spectral fatigue analysis. An approach of converting the load history to a series of closed notch stress-strain hysteresis loops and several open notch stress-strain hysteresis curves is proposed and demonstrated under variable amplitude loading. The approach is based on analytical notch stress-strain estimations and consists of several steps to consider the material memory effect, overcoming some limitations of the existing methods. To determine the fatigue damage for the variable amplitude loading, a design fatigue curve is derived considering the uncertainty in the fatigue lives and load sequence effects. The intrinsic fatigue limit concept is used to filter the small amplitude cycles that do not have a damaging effect. The fatigue strength of the butt-welded joint is analyzed, taking the weld-induced residual stress and misalignment effects into account explicitly. The notch mean stresses or strain amplitudes of the cycles are significantly enhanced because of the presence of a high level of weld-induced tensile residual stress or misalignment, resulting in highly severe fatigue damage.

1. Introduction

Complex ship structures containing geometrical and material discontinuities are prone to fatigue because of cyclic loads. Therefore, fatigue strength assessment has been an important criterion in the ship structural design (Guedes Soares & Moan 1991). Various fatigue design concepts for the assessment of welded joints, where fatigue failures mostly originate, are applied (Xu 1997; Radaj et al. 2006), and they can be classified into two types. The first one is based on S-N curves in combination with the Palmgren-Miner rule, and the second one is based on the crack propagation models and failure criteria.
Study on Torsional Vibration Characteristics of Cross Shaft Universal Coupling
Authors: Xiao Nengqi , Xu Xiang , Zhou Ruiping , Chen Baojia
Published: January 2021

In this work, the ship propulsion shaft system with cruciform universal coupling is studied. First, based on the analysis of the structure and characteristics of the cross-axis universal coupling, the motion relations and expressions between the components of the universal coupling are established by using the coordinate transformation method. Second, the characteristics of the four submodels of the head mass point element, the end mass point element, the universal coupling mass point element, and other mass point elements are discussed, and the corresponding torsional vibration differential equations of the four submodels are established. On this basis, the mathematical model of the propulsion shafting system and the differential equations of torsional vibration are established by using the modularization method and lumped parameter method. Finally, the torsional vibration modes and response characteristics of the shafts are calculated and analyzed by using the system matrix method when the external load driving torques of the universal coupling, propeller, and diesel engine are considered. At the same time, the correctness of the mathematical model and calculation method is verified by the test and comparative analysis of ship propulsion shafts. It lays a theoretical foundation for further research on torsional vibration characteristics and mechanisms of the ship propulsion shafting system based on universal coupling.

Introduction

Universal coupling is a common connection component of mechanical shaft system transmission. It is a common mechanism that can be used to transfer motion and torque. Universal coupling has no requirement for neutrality between the two axes connected. It can be used for intersecting, parallel or staggered multiposition relations, and can still ensure the continuous rotation of the two axes connected. Compared with the belt drive and chain drive, universal coupling has the advantages of large transmission range, compact transmission, high transmission efficiency, and convenient maintenance. Therefore, it is widely used in ships, automobiles, lifting and transportation (Avrigean et al. 2015; Chang et al. 2017), engineering machinery, and other equipment. Because of the manufacturing error, assembly error, and the failure to keep synchronous rotation between the driving shaft and the driven shaft in the working process, additional inertia moment of the universal coupling is generated, which causes the vibration of the system and even leads to the fracture of the universal coupling in serious cases.
CFD Simulations and Experiments of a Submarine in Turn, Zigzag, and Surfacing Maneuvers
Authors: Carrica Pablo M. , Kerkvliet Maarten , Quadvlieg Frans , Martin J. Ezequiel
Published: January 2021

We present simulations and experiments of the generic submarine Joubert BB2 performing standard turn, zigzag, and surfacing maneuvers in calm water at depth. The free-sailing experiments, performed at Maritime Research Institute Netherlands (MARIN), are unique in that they present an open dataset for the community to benchmark maneuvering prediction methodologies. Computations were performed with explicitly gridded sailplanes, tail planes, and propellers using a dynamic overset technique. This study analyzes a 20-degree turning maneuver with vertical control commanding the stern planes and a 20/20 zigzag maneuver with vertical control commanding both sail and stern planes, both of them at a nominal speed of 10 knots, and a 20-degree rise maneuver with horizontal control at 12 knots. The results show that computational fluid dynamics can predict well motions and speeds for free-sailing conditions, but controller commands are harder to replicate. Computations of the rise maneuver with surfacing compare well with experiments, including a crashback maneuver to stop the submarine.

Introduction

Simulation of free-running submarine maneuvers is demanding in terms of computational fluid dynamics (CFD) capabilities and computational resources. Full 6-DoF motions, moving appendages, control algorithms, and scalable performance are some of the requirements to execute free-running maneuvering simulations. Open literature data for validation of submarine maneuvers are very limited and consist mostly of static conditions (see for instance rotating arm [Toxopeus et al. 2012] and static drift [Roddy 1990; Toxopeus 2008] data for Defense Advanced Research Projects Agency (DARPA) Suboff and static drift [Quick & Woodyatt 2014] for the Joubert hull form [Joubert 2006]). A new dataset has been recently made available to the research community for the generic submarine model BB2 (Overpelt et al. 2015), based on the Joubert hull form.
An Experimental Investigation on Reduction Effect of Damping Devices for the Recessing Type Moonpool with a Large Aspect Ratio
Authors: Xianghong Huang , Wei Xiao , Xiongliang Yao , Jiayang Gu , Zhiyong Jiang
Published: January 2021

Compared with the square and circle moonpools, the rectangular moonpool with a large aspect ratio is more conducive to install the equipment. To reduce fluid motion in the rectangular moonpool with a large aspect ratio, a recess is installed in the moonpool. However, the fluid motion in a recessing type moonpool with a large aspect ratio has been rarely studied. In this study, a series of experiments are carried out to investigate on the hydrodynamic characteristics of fluid in the recessing type moonpool with a large aspect ratio. To facilitate the monitoring of the fluid motions, experiments are carried out in a transparent wave channel with the model made up of transparent acrylic. According to the experiment results, there are some complicated fluid motions in the moonpool. Under the resonance condition, the fluid moves violently in the moonpool. To reduce the fluid motion in the recessing type moonpool, three damping devices including the positive grid of flaps, the negative grid of flaps, and the grid of baffles are proposed. The reduction effect of the three damping devices is investigated experimentally. The damping devices have good reduction effects at most time. The smaller the incident wave period, the better is the reduction effect.

Introduction

The moonpools run vertically through the hull of ships or marine structures, providing a sheltered working environment under harsh ocean conditions. The fluid motion in the moonpool is similar to that in the slit between the ships or rectangular bodies (Faltinsen et al. 2007; Mavrakos & Chatjigeorgiou 2009; Ikeda et al. 2012; Chen et al. 2014; Heo et al. 2014; Zhang & Bandyk 2014; Faltinsen & Timokha 2015; Yu et al. 2017; Gao et al. 2019d). Two dominant types of fluid motions, the piston motion and the sloshing motion, are discussed (Fukuda 1977; Molin 2001; McIver 2005; Kristiansen & Faltinsen 2012; Zhou & Zhang 2013).
Wall-Modeled LES for Ship Hydrodynamics in Model Scale
Authors: Liefvendahl Mattias , Johansson Mattias
Published: January 2021

A complete approach for wall-modeled large-eddy simulation (WMLES) is demonstrated for the simulation of the flow around a bulk carrier in the model scale. Essential components of the method are an a-priori estimate of the thickness of the turbulent boundary layer (TBL) over the hull and to use an unstructured grid with the appropriate resolution relative to this thickness. Expressions from the literature for the scaling of the computational cost, in terms of the grid size, with Reynolds number, are adapted in this application. It is shown that WMLES is possible for model scale ship hydrodynamics, with ∼108 grid cells, which is a gain of at least one order of magnitude as compared with wall-resolving LES. For the canonical case of a flat-plate TBL, the effects of wall model parameters and grid cell topology on the predictive accuracy of the method are investigated. For the flat-plate case, WMLES results are compared with results from direct numerical simulation, RANS (Reynolds-averaged Navier-Stokes), and semi-empirical formulas. For the bulk carrier flow, WMLES and RANS are compared, but further validation is needed to assess the predictive accuracy of the approach.
The SNAME Ship Production Committee—Overview
Authors: Barham F. Baxter
Published: January 2021

The Society of Naval Architects and Marine Engineers formed its Ship Production Committee (SPC) in 1970 to address research and development in the ship production field. The Merchant Marine Act of 1936, as amended in 1970, charged the Secretary of Commerce to "collaborate with … shipbuilders in developing plans for the economic construction of vessels." The Maritime Administration selected the newly formed Ship Production Committee to provide industry management and technical input. The resulting cooperative effort has become known as the National Shipbuilding Research Program (NSRP). This paper provides a brief history of the SPC and the NSRP, notes the growing need for technical input to the program and shows how the SPC is changing to meet evolving ship production research demands and opportunities. Appendix A lists projects underway and planned. Appendix Β is a listing of project reports covering work completed under the National Shipbuilding Research Program.
The Use of Proximity Probes for Sterntube Boring Verification and Tailshaft Monitoring on Trials and in Service
Authors: Vassilopoulos L.
Published: January 2021

After reviewing the severity of tailshaft to stern bearing misalignment due to inadequate stern tube boring, the paper introduces the proximity probe as a tool to be used in ship construction that can help avoid bearing failures during dock trials and sea trials. The key elements of an instrumentation system that has been designed and used on board several ships are first discussed. A review is then presented of the special tasks that must be undertaken during the installation, calibration, data gathering and analysis phases. Specific examples of this approach to shaft alignment are cited with reference to a converted containership, a modern tanker and a collier.
Rationalization of Shipyard Information Flows for Improved Shipbuilding Productivity
Authors: Steller Mitchell E. , Dibner Brent
Published: January 2021

This paper provides a practical approach to rationalization of shipyard information flows through procedures which analyze the quality and quantity of information produced by and received by shipyard employees. An improvement in the yard's productivity is gained through better quality and timeliness of management information, elimination of redundant or unnecessary reports, streamlining of reports, and reduced distribution of the information. The process to achieve these goals is based on a microcomputer-assisted analysis of existing information flows. An inventory of reports and management information is developed to include distribution, frequency, computerized versus manual production, size, and use of the information. Based on the analysis, recommended rationalization can result in productivity gains (effective use of management and indirect labor time, timely and accurate decision-making, improved operations management, etc.) and in cost reductions (reduced report production, distribution, and computer costs, minimization of manufacturing error, smaller indirect staff, etc.).
Considerations Regarding Improved Productivity Based upon Experience for Series Production of Merchant Ships
Authors: Sverdrup C. F.
Published: January 2021

The paper reports on the measures taken over two decades by a major European shipbuilder at improving productivity in order to cope with both stiff foreign competition and depressed market conditions. For the series production of a standard merchant ship, the actual labor productivity improvements that can be achieved are demonstrated by shipbuilding methods standardization, work simplification, production bottleneck elimination, wage incentives, design simplification, improved planning, and prudent subcontracting.
Toward More-Productive Naval Shipbuilding—Results of an Assessment by the National Research Council
Authors: Bookman Charles A.
Published: January 2021

A three-year assessment of opportunities for productivity improvement in U.S. naval shipbuilding, conducted by the Committee on U.S. Shipbuilding Technology of the National Research Council, focused In part on the role and use of computers in shipbuilding. This paper describes the committee's work, and comments on the computerization of ship design, engineering and production, and on the modernization of shipbuilding management systems.
Higher-Strength Steels Specially Processed for High Heat Input Welding
Authors: Stern I. L. , Wheatcroft M. , Ku D. Y.
Published: January 2021

ABS Grade EH36 steel plates, specially formulated and produced with advanced metallurgical techniques, are shown to have a significantly greater resistance to weld heat-affected zone (HAZ) degradation that conventional EH36 steel. Welds made in these steels with the electroslag welding process at high heat input rates retained adequate toughness in the heat-affected zone at --4°F (-20°C); similar welds in conventional EH36 steel plate exhibit excessive HAZ toughness loss. This effect was confirmed on the basis of small-scale Charpy V-notch and large-scale explosion bulge testing. In view of their superior resistance to HAZ degradation, the steels should also be useful for applications where HAZ degradation is of particular concern, such as for American Bureau of Shipping (ABS), U.S. Coast Guard, and International Maritime Organization (IMO) weld requirements for liquefied gas carriers.