Influence of Soil’s Vertical Stiffness on Estimation of Fatigue Life for Steel Catenary Risers (SCRs)

2020 ◽  
Author(s):  
Jianchun Cao ◽  
Xingnian Chen ◽  
Jingyun Cheng ◽  
Peimin Cao
Keyword(s):  
Fatigue Life ◽  
Soil Condition ◽  
Vertical Stiffness ◽  
Bridge Method ◽  
Laboratory Test Results ◽  
Study Results ◽  
Conventional Methods ◽  
The Difference ◽  
Scr System ◽  
The Impact

Abstract Fatigue damage estimation is a key part in a Steel Catenary Riser (SCR) system design. The riser-soil interaction has a significant influence on the fatigue assessment for a SCR system at the Touch-Down Zone (TDZ) because the soil’s vertical stiffness is a critical parameter. The conventional methods developed to calculate the soil’s vertical stiffness, for example, DNV method [10], Bridge method [4] and Audibert method [3], were based on the assumption that at the TDZ area the soil mass being interacted by the pipe is always under intact condition. Recently, Chen et al. published a newly developed method [5, 6], which was based on the laboratory test results carried out by Texas A&M University in the late 1980s and was further verified by recent laboratory displacement-controlled tests by Texas A&M University [2], resulting in softer soil’s vertical stiffness. In order to understand the difference between Chen method and the conventional methods as well as the influence of Chen method on the SCR design, a study was carried out for a given soil condition and three typical sizes of riser pipes and is documented in this paper. In this paper, firstly, various methods used to calculate soil’s vertical stiffness, i.e., DNV method, Bridge method, Audibert method, and Chen method, were briefly introduced. Secondly, a discussion was performed on the model of the conventional methods and the model of Chen method. Thirdly, as an example for a given soil condition, the soil’s vertical stiffness was estimated using these methods respectively for 6″-dia., 12″-dia., and 18″-dia. riser pipes. Finally, the fatigue damages for various riser pipes were computed using the estimated soil’s vertical stiffness and a comparison on the estimated fatigue damages was performed. The study results showed that the soil’s vertical stiffness estimated by Chen method was about one order magnitude weaker than these estimated by the conventional methods. In other words, the soil’s vertical stiffness estimated by the conventional methods was about 5 to 11 times that estimated by Chen method. The pipe’s fatigue life estimated using the soil’s vertical stiffness of Chen method was about 1.5 times (i.e., 50% longer than) that estimated using the soil’s vertical stiffness of the conventional methods. These study results could improve a SCRs designer’s understanding on: 1) the difference between the model of the conventional methods and the model of Chen method, 2) the impact of Chen method on the estimated fatigue life, and 3) that as the model of the conventional methods is a closer representative of the prototype and their results are more conservative, it is recommended to use the conventional methods for SCRs design. Eventually, these will help the designers to select an appropriate method for calculating the soil’s vertical stiffness in the SCRs design.

Improving Fatigue Life of Riveted Joints by Rivet Hole Sizing

2014 ◽  
Vol 598 ◽  
pp. 141-146
Author(s):  
Adam Lipski ◽  
Zbigniew Lis
Keyword(s):  
Fatigue Life ◽  
Fold Increase ◽  
Fatigue Tests ◽  
Aviation Industry ◽  
Lap Joint ◽  
Riveted Joints ◽  
Riveting Process ◽  
The Difference ◽  
Structural Connection ◽  
The Impact

The aim of this paper is to assess the impact of the rivet hole sizing process on the fatigue life based on the example of the structural connections characteristic for riveted joints used in aviation industry. Test specimens reflected the structural connection consisting in a riveted lap joint of an airplane plating stiffened with a T-bar. Connected plates and the T-bar are made of D16CzATW aluminum alloy. 3 mm diameter oval head solid rivets for aviation-related purposes were made of PA24 aluminum. During fatigue tests, individual specimens with non-sized holes and with sized holes were subjected to uniaxial, one-sided, fixed-amplitude loading (R = 0). It can be concluded from the fatigue life comparison that introduction of an additional operation in the riveting process, i.e. the hole sizing, results in significant, about two-fold increase of the fatigue life of the riveted structural connection, even at slight sizing degree. The difference of the specimen damage nature was observed between specimens with sized and non-sized holes.

scholarly journals A májfunkció romlásának rizikófaktorai sikeres vesetranszplantációt követően

2019 ◽  
Vol 160 (5) ◽  
pp. 186-190
Author(s):  
Bernadett Borda ◽  
Attila Nemes ◽  
Csaba Lengyel ◽  
Tamás Várkonyi ◽  
Ferenc Rárosi ◽  
...  
Keyword(s):  
Liver Function ◽  
Immunosuppressive Therapy ◽  
Liver Enzymes ◽  
Graft Loss ◽  
Study Results ◽  
Allograft Function ◽  
The Difference ◽  
The Impact ◽  
The Relationship

Abstract: Introduction: Increase of liver function is one of the most common complications after kidney transplantation due to the use of immunosuppressive therapy and hyperlipidemia in addition to hepatitis C virus (HCV) infection. Method: Following the selection criteria (n = 59), the study is based on applied immunosuppressive therapy, baseline data of patients, further correlation between HCV and liver function deterioration. Patients were subjected to fasting laboratory examination to monitor serum electrolytes, uric acid and albumin levels. We looked at the effects of immunosuppressive therapy on the lipids (TG, TC, HDL, LDL) and liver enzymes (GOT, GPT, ALP, GGT). The analysis of the relationship between lipids and liver enzymes was also included in our study. Results: The data basics were not significantly different between the tacrolimus and the cyclosporine groups. In the laboratory results, Mg levels were significantly different between the two groups (p = 0.044). The impact of HCV on the liver function was significantly different on GGT (p = 0.008). We examed the lipids and liver function level between the tacrolimus and the patients receiving cyclosporine-based immunosuppression and the total cholesterol (p = 0.005) and GOT (p = 0.05) were significantly different between the two groups. Hyperlipidemia was associated with 26% of patients taking tacrolimus-based immunosuppression, and 89% of those receiving cyclosporine; the difference was significant (p = 0.002). Regarding the effect of hyperlipidemia on liver enzymes, ALP (p = 0.006) and GGT (p = 0.0001) were significantly higher. Conclusion: Increases in hepatic enzymes, ALT and GGT indicate the damage to hepatocytes. Beside the increase of liver function, which is the main risk factor in hepatitis on HCV soil, the applied immunosuppressive therapy and hyperlipidemia lead to degradation of allograft function and long-term graft loss. Orv hetil. 2019; 160(5): 186–190.

scholarly journals The Fair Value Measurement Challenges Faced by the External Auditor: Kurdistan Region -Iraq

2021 ◽  
Vol 5 (1) ◽  
pp. 93-100
Author(s):  
Firas N. Mardan
Keyword(s):  
Fair Value ◽  
Fair Value Accounting ◽  
External Auditors ◽  
Value Evaluation ◽  
Study Results ◽  
Important Challenge ◽  
External Auditor ◽  
The Difference ◽  
Value Measurement ◽  
The Impact

This study aimed to identify the most important challenges facing auditors when measuring fair value FVMs from three axes, namely identifying which challenges are most influencing auditors to direct attention towards them, and revealing the extent to which the inherent auditing risks are affected by fair value evaluation estimates. The third axis of this study raises discussions about the reliability of audit evidence relating to fair value and assures that disclosed and recognized fair values ​​are guiding values. The field study was applied to a sample of external auditors in the West Bank, where the researcher used the descriptive analytical approach in the field side and used the inductive approach to test the study hypotheses. The study found a set of results; the most important challenge facing the auditor in auditing fair value estimates is the lack of access to recent amendments to the international auditing standards for fair value accounting estimates. The study results also confirmed the impact of auditing risks with fair value estimates and measuring them at higher rates in many cases, including (the absence of active markets, the presence of significant misstatements, and the difference in the basis for measuring fair value).

scholarly journals A Study on the Relationship between Proprietorship Concentration and Profit Management in the Companies Listed in Tehran Stock Exchange

2017 ◽  
Vol 19 ◽  
pp. 72
Author(s):  
Soghra Ranjbarian ◽  
Akbar Zavari Rezaei ◽  
Asghar Azizi
Keyword(s):  
Institutional Investors ◽  
Stock Exchange ◽  
Correlation Coefficients ◽  
Computer Application ◽  
Coefficient Of Determination ◽  
Lack Of Information ◽  
Study Results ◽  
The Difference ◽  
The Impact ◽  
The Relationship

The presence of institutional investors may change the behaviors of companies. The impact of institutional investors on management decisions on financial affairs have been proven in other studies; yet, the present study aims to investigate the relationship between lack of information symmetry an concentration of proprietorship with profit management in the companies listed in Tehran Stock Exchange. The period under study included years 2004 to 2009. Rahavard Novin Computer application was utilized to collect the data; then they were calculated using Microsoft Excel.  SPSS computer application was used to test research hypothesis and conduct other statistical analysis using statistical methods like descriptive statistics, correlation (correlation coefficient, coefficient of determination), regression analysis and testing its coefficients, correlation analysis and test of coefficients and significance of the difference between two correlation coefficients. A total of 109 active companies in the stock exchange were selected as the sample of the study. Results on the first hypothesis revealed that the relationship between concentration of proprietorship and lack of information symmetry. In case of the second hypothesis, it is predicted that there is a significant relationship between profit management with lack of information symmetry and concentration of proprietorship. According to research results, investors and analysts ought to pay attention to factors like proprietorship composition, the level of information symmetry along with the figures published by the companies when making short and long-term decisions.

scholarly journals Does the Difference in Urban Public Facility Allocation Cause Spatial Inequality in Housing Prices? Evidence from Chongqing, China

2019 ◽  
Vol 11 (21) ◽  
pp. 6096 ◽  
Author(s):  
Zhang ◽  
Zhou ◽  
Mao
Keyword(s):  
Equilibrium State ◽  
Housing Market ◽  
Housing Prices ◽  
Spatial Inequality ◽  
Public Facility ◽  
Spatial Equilibrium ◽  
Public Facilities ◽  
Study Results ◽  
The Difference ◽  
The Impact

The current study argues that the capitalisation effect of urban public facilities on housing will be considerable when the accessibility or availability of facilities has a serious stake in the location or property rights of houses. The supply level and supply quantity of urban public facilities determine whether there is a significant difference in the accessibility or availability of facilities amongst neighbourhoods, and subsequently determines whether the capitalisation effect of facilities on surrounding houses is considerable, which ultimately affects the spatial inequality in housing prices (i.e. spatial dispersion of housing prices). However, previous studies have rarely considered the fact that the supply and demand of urban public facilities vary with the type of facilities. Thus, according to the law of diminishing marginal utility, the current study proposes a theoretical framework for the impact of the allocation of urban public facilities at different supply levels on the spatial inequity in housing prices and verifies this through a case study. Results indicate that the difference in urban public facility allocation caused by the unequal supply quantity or unbalanced spatial distribution has a notable impact on the spatial inequality in housing prices. There are three states of allocation of urban public facilities available according to different supply levels, namely, disequilibrium, quantitative equilibrium and spatial equilibrium:(І) Scarce and high-quality public resources that may always be in the disequilibrium state create a substantial capitalisation effect on nearby housing, and their presence will aggravate spatial inequality in housing prices; (П) Public facilities that can only reach the quantitative equilibrium state have a considerable capitalisation effect on nearby housing, and their supply densities have a positive impact on the spatial inequality in housing prices; (Ш) Public facilities in the spatial equilibrium state have a negligible capitalisation effect on nearby housing, and their supply densities have a negative impact on the spatial inequality in housing prices. Therefore, it is reasonable to argue that urban public facilities at different supply levels have a diversified impact on the housing market. This study can contribute to having a comprehensive and in-depth understanding of the diversified impact of urban public facilities on the housing market.

scholarly journals A study effects of injection pressure and wall temperature on the mixing process of NOx and NH3 in Selective Catalytic Reduction system

2020 ◽  
Vol 11 (1) ◽  
pp. 45
Author(s):  
Muhammad Khristamto Aditya Wardana ◽  
Ocktaeck Lim
Keyword(s):  
Diesel Engine ◽  
Selective Catalytic Reduction ◽  
Wall Temperature ◽  
Public Transportation ◽  
Catalytic Reduction ◽  
Numerical Study ◽  
Mixing Process ◽  
Study Results ◽  
Scr System ◽  
The Impact

Diesel engines are commonly used for public transportation on-road and off-road applications. Growth production of the diesel engine is very significant from year to year. Nitride Oxide (NOx) from diesel engine was one of the major sources of air pollution. Selective Catalytic Reduction (SCR) has been successfully used to reduce NOx from a diesel engine with a chemical reaction from ammonia (NH3). The mixing reaction between NOx and NH3 reaction can produce steam (H2O) and Nitrogen (N2). However, ammonia uniformity pattern usually not homogenization and the ammonia was difficult to mix with NOx. The constant air flows incomplete to assist the spray injector to spread NH3 to all corners of SCR. The impact study of turbulent phenomena and standard k-epsilon Low-Reynolds Number model to the mixing process in the SCR system using STARCCM+. The simulation studies are conducted under different pressure (4 to 6 bars), the injection rate (0.04 g/s) and temperature (338 K – 553 K) and the high pressure and high velocity magnitude creating turbulent swirl flow. The ammonia decomposition process and mixing process with NOx were investigated using a box with optical access. The simulation and numerical study results validated using back pressure value and the distribution of NOx concentration value from the catalyst outlet. The wall temperature will increase the urea evaporation to generate ammonia and gas pressure will increase the mixing process and chemical process in the SCR system. These reactions enable to optimize the SCR system technology which eventually able to reduce the NOx quantity from a diesel engine.

Evaluation of the impact of public investment programs on social and economic performance of territories

2019 ◽  
pp. 109-123
Author(s):  
I. E. Limonov ◽  
M. V. Nesena
Keyword(s):  
Bayesian Modeling ◽  
Positive Impact ◽  
Public Investment ◽  
Difference In Differences ◽  
The Public ◽  
Export Activity ◽  
Regional Investment ◽  
The Difference ◽  
The Impact ◽  
Development Institution

The purpose of this study is to evaluate the impact of public investment programs on the socio-economic development of territories. As a case, the federal target programs for the development of regions and investment programs of the financial development institution — Vnesheconombank, designed to solve the problems of regional development are considered. The impact of the public interventions were evaluated by the “difference in differences” method using Bayesian modeling. The results of the evaluation suggest the positive impact of federal target programs on the total factor productivity of regions and on innovation; and that regional investment programs of Vnesheconombank are improving the export activity. All of the investments considered are likely to have contributed to the reduction of unemployment, but their implementation has been accompanied by an increase in social inequality.

Income Diversification and Bank Efficiency in Vietnam

2017 ◽  
pp. 52-67
Author(s):  
Sang Nguyen Minh
Keyword(s):  
Regression Model ◽  
Commercial Banks ◽  
Banking System ◽  
Operational Efficiency ◽  
Commercial Banking ◽  
Tobit Regression ◽  
Income Diversification ◽  
Positive Effects ◽  
Study Results ◽  
The Impact

This study uses the DEA (Data Envelopment Analysis) method to estimate the technical efficiency index of 34 Vietnamese commercial banks in the period 2007-2015, and then it analyzes the impact of income diversification on the operational efficiency of Vietnamese commercial banks through a censored regression model - the Tobit regression model. Research results indicate that income diversification has positive effects on the operational efficiency of Vietnamese commercial banks in the research period. Based on study results, in this research some recommendations forpolicy are given to enhance the operational efficiency of Vietnam’s commercial banking system.

Some reflections on social structure: Theoretical and practical aspects

2020 ◽  
Vol 18 (6) ◽  
pp. 1063-1078
Author(s):  
T.N. Skorobogatova ◽  
I.Yu. Marakhovskaya
Keyword(s):  
Service Industry ◽  
External Factors ◽  
Infrastructure Development ◽  
Social Infrastructure ◽  
Social Sphere ◽  
The Social ◽  
Study Results ◽  
The Republic ◽  
Internal And External Factors ◽  
The Impact

Subject. This article discusses the role of social infrastructure in the national economy and analyzes the relationship between the notions of Infrastructure, Service Industry and Non-Productive Sphere. Objectives. The article aims to outline a methodology for development of the social infrastructure of Russia's regions. Methods. For the study, we used the methods of statistical and comparative analyses. The Republic of Crimea and Rostov Oblast's social infrastructure development was considered as a case study. Results. The article finds that the level of social infrastructure is determined by a number of internal and external factors. By analyzing and assessing such factors, it is possible to develop promising areas for the social sphere advancement. Conclusions. Assessment and analysis of internal factors largely determined by the region's characteristics, as well as a comprehensive consideration of the impact of external factors will help ensure the competitiveness of the region's economy.

The Use of Multimedia and its Impact on Bangladeshi EFL Learners at Tertiary Level

2020 ◽  
Vol 4 (2) ◽  
pp. 150
Author(s):  
Farzana Sharmin Pamela Islam
Keyword(s):  
Language Learning ◽  
Academic Writing ◽  
Teaching And Learning ◽  
English Language ◽  
Capital City ◽  
Tertiary Level ◽  
Language Classroom ◽  
The Difference ◽  
The Government ◽  
The Impact

As 21st century is the era of modern technologies with different aspects, it offers us to make the best use of them. After tape recorder and overhead projector (OHP), multimedia has become an important part of language classroom facilities for its unique and effective application in delivering and learning lesson. Although in many parts of Bangladesh, a South Asian developing country, where English enjoys the status of a foreign language, the use of multimedia in teaching and learning is viewed as a matter of luxury. However, nowadays the usefulness and the necessity of it are well recognized by the academics as well as the government. The study aims to focus on the difference between a traditional classroom void of multimedia and multimedia equipped classrooms at university level by explaining how multimedia support the students with enhanced opportunity to interact with diverse texts that give them more in-depth comprehension of the subject. It also focuses on audio-visual advantage of multimedia on the students’ English language learning. The study has followed a qualitative method to get an in-depth understanding of the impact of using multimedia in an English language classroom at tertiary level. For this purpose, the data have been collected from two different sources. Firstly, from students’ written response to  an open ended question as to their comparative experience of learning  lessons with and without multimedia facilities; and secondly, through  observation of English language classes at a private university of Dhaka, the capital city of Bangladesh. The discussion of the study is limited to  the use of multimedia in English language classroom using cartoons, images and music with a view to enhance students’ skills in academic writing, critical analysis of image and critical appreciation of music. For this purpose, cartoons in English language, images from Google and music from You Tube have got focused discussion in this paper.

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