scholarly journals Analysis of the Root Causes of Damage to the Edges of Tank Manholes on the Main Deck of Handy-Size Bulk Carriers

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 632
Author(s):  
Leszek Chybowski ◽  
Katarzyna Gawdzińska
Keyword(s):  
Welded Joints ◽  
Poor Quality ◽  
Test Results ◽  
Quality Steel ◽  
Wear Life ◽  
Bulk Carriers ◽  
Deck Cracks ◽  
Scanning Electron Microscope Fractography ◽  
Metallic Impurities

This study analyzes the root causes of cracks in the deck plating around tank manholes. Four handy-size bulk carriers built in one shipyard were analyzed. In all cases, deck cracks were found near manholes, and the average time from the commencement of operation until the occurrence of cracks was 1356 days. Due to this short wear-life of the vessel’s structural material, the authors believed that it was unlikely to be caused by corrosion fatigue. The authors hypothesized that main decks cracked around manholes because of very poor-quality welded joints and poor-quality steel (large amounts of non-metallic impurities) used to make the manholes. In order to verify this hypothesis, on each of the vessels, material samples were collected from near the cracks and then examined thoroughly. Each sample was subjected to the macroscopic examination of the natural surfaces of cracks and their vicinity, microscopic examination of the material, mechanical property tests, and scanning electron microscope fractography for samples obtained after impact tests. The examination and test results were used to draw detailed conclusions for each case study. The general conclusions based on examination of the whole damage population validated the authors’ hypothesis that main decks cracked around manholes because of very poor-quality welded joints and poor-quality steel used to make the manholes.

Structural Failures of Bulk Carriers

1995 ◽  
Vol 209 (2) ◽  
pp. 83-91 ◽  
Author(s):  
J Jubb
Keyword(s):  
Structural Failure ◽  
Bulk Carrier ◽  
Detail Design ◽  
The Pacific ◽  
Local Stresses ◽  
Bulk Carriers ◽  
The Pacific Ocean ◽  
Structural Failures ◽  
Deck Cracks

Structural failures of bulk carriers continue at a steady and unacceptable rate, claiming some 150 lives per year. This paper explains why bulk carriers are vulnerable to structural failure either because side shell plating falls out allowing ingress of seawater or the deck cracks open. Inadequate detail design, material without guaranteed fracture toughness and limitations of current inspection programmes are identified as fundamental weaknesses. The paper includes important information from a case study of six oil bulk ore carriers prone to deck cracking. One of the group of six which sank in 1980 was traced 4200 metres down on the floor of the Pacific Ocean in June 1994 and the results of this initial search are reviewed. There is a genuine need to go back to basics. Designing from first principles to determine local stresses is an important first step rather than the current use of prescriptive rules. All subsequent steps in bulk carrier construction and maintenance should be subject to a penetrating review.

PENGKAJIAN KEKUATAN BETON STRUKTUR JEMBATAN PASCA KEBAKARAN

2013 ◽  
Vol 12 (3) ◽  
Author(s):  
Sudarmadi Sudarmadi
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Test Results ◽  
Concrete Compressive Strength ◽  
Strength Assessment ◽  
Concrete Testing

In this paper a case study about concrete strength assessment of bridge structure experiencing fire is discussed. Assessment methods include activities of visual inspection, concrete testing by Hammer Test, Ultrasonic Pulse Velocity Test, and Core Test. Then, test results are compared with the requirement of RSNI T-12-2004. Test results show that surface concrete at the location of fire deteriorates so that its quality is decreased into the category of Very Poor with ultrasonic pulse velocity ranges between 1,14 – 1,74 km/s. From test results also it can be known that concrete compressive strength of inner part of bridge pier ranges about 267 – 274 kg/cm2 and concrete compressive strength of beam and plate experiencing fire directly is about 173 kg/cm2 and 159 kg/cm2. It can be concluded that surface concrete strength at the location of fire does not meet the requirement of RSNI T-12-2004. So, repair on surface concrete of pier, beam, and plate at the location of fire is required.

scholarly journals Mind the Gap: Why the Landscape Planning System in Sardinia Does Not Work

2021 ◽  
Vol 13 (13) ◽  
pp. 7300
Author(s):  
Anna Maria Colavitti ◽  
Alessio Floris ◽  
Sergio Serra
Keyword(s):  
Landscape Planning ◽  
Comparative Method ◽  
Poor Quality ◽  
Planning System ◽  
Local Planning ◽  
The Common ◽  
Regional Landscape ◽  
Landscape Protection

In Italy, after the introduction of the Code of Cultural Heritage and Landscape in 2004, the Regional Landscape Plan (RLP) has acquired a coordination role in the urban planning system, for the implementation of policies for landscape protection and valorisation. The case study of the RLP of Sardinia is a paradigmatic application to the coastal area of the island, which is considered most vulnerable and subject to settlement pressure. The objectives of preservation and valorisation of the territorial resources should be transferred into local planning instruments by adopting strategies aimed at the preservation of the consolidated urban fabric, at the requalification and completion of the existing built-up areas according to the principles of land take limitation and increase in urban quality. The paper investigates the state of implementation and the level of integration of landscape contents in the local plans that have been adapted to the RLP, using a qualitative comparative method. In addition, the results of the plan coherence checks, elaborated by the regional monitoring bodies after the adaptation process, have been analysed to identify the common criticalities and weaknesses. The results highlight the lack of effectiveness of the RLP, after more than a decade since its approval, considering the limited number of adequate local plans and the poor quality of their analytical and regulative contents in terms of landscape protection and valorisation. Conclusions suggest some possible ways to revise the RLP, focusing on the participation of local communities and the development of a new landscape culture.

The Properties of Welded Joints Made by 6082-T6 Aluminium Alloy and their Behaviour under Cyclic Loading Conditions

2015 ◽  
Vol 812 ◽  
pp. 375-380 ◽  
Author(s):  
D. Pósalaky ◽  
János Lukács
Keyword(s):  
Cyclic Loading ◽  
Automotive Industry ◽  
Welded Joints ◽  
Structural Engineering ◽  
Physical Simulation ◽  
Base Material ◽  
Point Of View ◽  
Test Results ◽  
Structural Elements ◽  
Effective Use

The magnitude of different aluminium alloys, especially the ones with higher strength, are increasing in the structural engineering, not just the usual applications (like the aerospace industry) but more likely in the automotive industry. There are more assumptions of the effective use of aluminium; we should highlight two important factors, the technological and the applicability criterions. The technological criterion is the joining of structural elements, frequently with welding thus the technological criterion ultimately is the weldability. The assumption of applicability comes from the loading capability of these structures, which is typically cyclic loading so the key issue from the point of view of applicability is the resistance to fatigue. This article represents physical simulation and fatigue test results both on the base material and on the welded joints.

Challenges to Overcome and Scaffolding to Build on

2019 ◽  
Vol 9 (3) ◽  
pp. 50-67
Author(s):  
Hao Yang ◽  
Zhiqiang Ma
Keyword(s):  
Teacher Perceptions ◽  
Flipped Classroom ◽  
Public University ◽  
Test Results ◽  
Learning Behavior ◽  
Long Term Effects ◽  
Exploratory Case Study ◽  
Flipped Classrooms

While current research on the flipped classroom generally focuses on test results and (or) student/teacher perceptions as a measurement of its pedagogical efficacy, students' adaptation to it and the essential conditions for its application are rarely explored. This exploratory case study aims to rectify this by examining how university students adapted to flipped classrooms implemented in a public university in East China. The findings suggest that while the flipped model is impeded by entrenched polarity between students in terms of their learning dispositions and academic competence, students do develop a prototype of theories of learning, a sense of better self through learning from their peers and an awareness of the importance of intrinsic motivation. A gradualist approach is thus proposed for implementing flipped classrooms, which requires longitudinal studies accordingly to understand its long-term effects on learning behavior hitherto left unexplored.

scholarly journals Experimental Study on the Transverse Effective Bending Rigidity of Segmental Lining Structures

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Yong-feng Tang ◽  
Han-cheng Chen ◽  
Zhen-wei Ye ◽  
Ting-jin Liu ◽  
Yu-bing Yang
Keyword(s):  
Regression Equation ◽  
Shield Tunnel ◽  
Outer Diameter ◽  
Test Results ◽  
Bending Rigidity ◽  
Segmental Lining ◽  
Ring Model ◽  
Scale Models ◽  
Elastic Stage

The transverse effective rigidity ratio is a key parameter when the uniform rigidity ring model is adopted to design or numerically analyse segmental lining structures commonly used on a shield-driven tunnel. Traditionally, the transverse effective rigidity ratio η is treated as a constant, which can be evaluated through theoretical analysis and model tests. In this study, scale models were designed and tested to investigate the variation of the transverse effective rigidity ratio in the segmental linings’ flattening deformation process. The test results suggested that in the elastic stage, the transverse effective rigidity ratio fluctuated between 0.667 and 0.734 for the stagger-jointed rings and fluctuated between 0.503 and 0.642 for the straight-jointed rings. When segmental linings were squashed and started to crack at the circumferential joints, the transverse effective rigidity ratio decreases sharply. Then, a regression equation was obtained to fit the variation trend of η with the increase of horizontal convergence to the outer-diameter ratio (ΔD/Dout). Finally, in a case study, the regression equation was adapted to determine the value of η of an operated shield tunnel which was once surcharged accidentally and deformed severely so as to numerically predict the prospective deformation induced by the upcoming adjacent excavation. Numerical results indicated that as the value of η decreases, the horizontal convergences of shield tunnel induced by adjacent excavation increase significantly and even more than doubled in the case study. Comparatively, through taking account of the operating tunnels’ exiting transverse deformation, the predicted deformation tends to be unfavourable.

scholarly journals Investment Of Fixed Equipment Assets On Improving Profitability (case study cv.Parahyangan Express BranchKarawang)

2020 ◽  
Vol 17 (1) ◽  
pp. 30-42
Author(s):  
Sri Suartini ◽  
Dian Hakip Nurdiansyah ◽  
Sheli Rosdayanti
Keyword(s):  
Primary Data ◽  
Test Results ◽  
Fixed Asset ◽  
Financial Report ◽  
Verification Method ◽  
Average Value ◽  
Fixed Assets ◽  
Data Source ◽  
Fixed Asset Investment

The purpose of this study to determine how much influence of fixed asset investment vehicles against profitability CV. Parahyangan Express Karawang Branch. This research uses a descriptive verification method with a primary data source that is a financial report CV. Parahyangan Express Karawang Branch period 2007 to 2016. The result of this research is r average investment value CV. Parahyangan Express in the period 2007 until 2016 tends to decrease, the average value of profitability CV. Parahyang n Express in the period 2007 to 2016 tends to decline. Based on test results t comparison t arithmetic with t table showing 2.840> 2.093 t count more than t table. vehicle fixed asset investment has a significant effect on profitability in a CV. Parahyangan Express. The percentage of influence of fixed asset investment of 30% means 30 % development of profitability CV. Parahyangan Express is influenced by in-kind fixed assets while 70 % is influenced by other factors not examined in this study.

scholarly journals INFLUENCE OF MOTIVATION TO RESULT OF COGNITIVE LEARNING IN INTERGRATED NATURAL SCIENCES MODEL TEAM GAMES TOURNAMENT (TGT) ASSITANCE BY YUGIOH CARD

2019 ◽  
Vol 18 (2) ◽  
pp. 20
Author(s):  
Reda Harwinanda
Keyword(s):  
Science Learning ◽  
Cognitive Learning ◽  
Natural Sciences ◽  
Learning Motivation ◽  
Test Results ◽  
Simple Linear Regression ◽  
Team Games ◽  
Post Test ◽  
Positive Effect

The purpose of this study was to examine the effect of motivation on the result cognitive learning of the model TGT assisted YuGiOh Card. The population in this study were students of class VII semester 1 with the number of 16 students at MTs Baitul Amin Bali. The type of research design used was pre-experimental design with a one-shot case study. The study used 2 (two) variables examined in this study, namely motivation and result cognitive learning. The method used in data collection in this research is questionnaire (questionnaire), documentation and test. The collected data were analyzed using simple linear regression. Based on the motivation data obtained using themodel TGT assisted by the YuGiOh card in this study, it shows that students who are in the very good motivation category are 62.5% and good categories are 37.5%. Data on students' resultcognitive learning from post-test results can be categorized very well by 6%, both by 31%, enough by 44% and less by 19%. The influence of motivation on result cognitive learning using the model TGT assisted YuGiOh card is 27.2% while the remaining 72.8% is influenced by learning readiness, social support and learning facilities. The results showed that learning motivation had a positive effect on result cognitive learning in science learning using the model TGT assisted by YuGiOh card.

scholarly journals Kontribusi Muhasabah dalam Mengembangkan Resiliensi Pada Orang Tua Anak Berkebutuhan Khusus

2021 ◽  
Vol 6 (2) ◽  
pp. 244-262
Author(s):  
Fatma Laili Khoirun Nida
Keyword(s):  
Special Needs ◽  
Poor Quality ◽  
Children With Special Needs ◽  
Case Study Approach ◽  
Study Approach ◽  
Study Results ◽  
Resilience Factors ◽  
Depth Interviews

The phenomenon of the poor quality of parental care for children with disabilities makes resilience one of the psychological capital that contributes to improving the quality of care. This study describes how through a muhasabah intervention in Blimbingrejo Village, Nalumsari District, Jepara Regency. The purpose of this study was to provide information for parents of children with special needs about muhasabah interventions in developing the resilience abilities of parents when carrying out their care. The urgency of this research is to reduce parenting stress experienced by parents because of the developmental barriers of their children. This research is qualitative with a case study approach through in-depth interviews and observation techniques. The study results explain that the condition of children with special needs is often a stressor for their parents. However, parents can live with complete steadfastness as a form of their resilience. The pattern of resilience formed is supported mainly by thinking about what they are trying to do. There are indications of the meaning of resilience factors in the practice of muhasabah in the form of the ability to regulate emotions, develop optimism and empathy, control impulses and causal analysis, good self-efficacy and take wisdom as an indication of aspects of the reaching out process. The results of this study are helpful information in developing the concept and practice of caring for children with special needs.

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