scholarly journals A Short Note about the Impact Action of a Water Jet Stabilized by a Coaxial Air Stream in the Air and Underwater

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5015
Author(s):  
Josef Poláček ◽  
Irena Marie Hlaváčová ◽  
Martin Tyč
Keyword(s):  
Near Field ◽  
Pure Water ◽  
Air Flow ◽  
Relevant Literature ◽  
Short Note ◽  
Original Method ◽  
Water Jet ◽  
Impact Action ◽  
Dual Action ◽  
The Impact

A new original method, applying a coaxial protective airflow, was tested aiming to improve the pure water jet efficiency in surface layer removal or medium hard materials cutting or blasting. The dual action of the air flow is expected: the air co-flowing the water jet with approximately the same velocity should prevent the central jet from breaking up into tiny droplets in the near field, and simultaneously, it should support jet decomposition into big parts with enough destructive potential in the far-field. A brief survey of the relevant literature dealing with the water jet instability is presented, introducing four recognized breakup regimes. An original cutting head designed to generate a waterjet surrounded by protective coaxial air flow is introduced. The submitted device is supposed to operate within the first wind-induced regime. Two types of experiments, consisting of blasting limestone bricks placed either in the air or underwater, were realized. The depths of kerfs produced with different water pressures and air overpressures were evaluated. While no substantial positive effect was recognized in the air performance, the submerged blasting of the same material under similar conditions appeared to be promising.

scholarly journals Design and Simulation of Nozzle for Pure Water Jet Portable Cutting Tool

2019 ◽  
Vol 8 (12S2) ◽  
pp. 703-706
Keyword(s):  
Pressure Drop ◽  
Cross Sections ◽  
Pure Water ◽  
Water Jet ◽  
Element Analysis ◽  
Cutting Machine ◽  
Water Jet Cutting ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
The Impact

A pure water jet at subsonic speed provides an opportunity for application in cutting soft material with the advantage of not contaminating the workpiece. Inside the nozzle, water is flowing through various cross sections, which lead to pressure drop and loss of energy. This requires a nozzle with a design that causes minimum pressure drop. In this work, Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) were used to analyse the flow through five different nozzles. For each nozzle, the pressures of 10 MPa, 20 MPa and 30 MPa were applies at the inlet. For the inlet pressure of 10 MPa, the highest outlet velocity us 136.12 m/s at the pressure of 9.261 MPa. The impact pressure at stand distance of 0.5 mm and 1.0 mm were 8.26 MPa and 8.02 MPa, respectively. For this nozzle, the Factor of Safety for 10 MPa, 20 MPa and 30 MPa were 6.4, 3.2 and 2.961, respectively. The findings are relevant to the development of pure water jet cutting machine

scholarly journals Fragmentation Pattern and Removal Mechanism of Concrete Subjected to Abrasive Water Jet Impact

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jialiang Liu ◽  
Yujie Zhu ◽  
Yongzhi Xue ◽  
Hao Sun
Keyword(s):  
Transition Zone ◽  
Pure Water ◽  
Ct Scanning ◽  
Water Jet ◽  
Fragmentation Pattern ◽  
Abrasive Water Jet ◽  
Removal Mechanism ◽  
Jet Impact ◽  
Propagation Law ◽  
The Impact

Abrasive water jet (AWJ) breaking technology is suitable for the maintenance and repair of concrete structures, generating minimal dust, low tool wear, and no vibrations or selective destruction. The failure features and mechanisms of concrete subjected to AWJ impact are fundamental issues of AWJ breaking technology, which are also related to the safety and quality of engineering construction. Based on computed tomography (CT), scanning electron microscopy (SEM), and image processing technology, this paper studied the fragmentation pattern and removal mechanism of concrete under AWJ impact. The general failure characteristics and crack propagation law of concrete subjected to AWJ impact were described through AWJ impact concrete tests. The spatial distribution of damage in concrete subjected to AWJ impact can be divided into the intensive action zone, the transition zone, and the weak action zone. The removal mechanism of AWJ was discussed by comparing the impact performance of a pure water jet (PWJ) system. The results indicate that abrasive particles can cause cliff-shaped fracture and lip-shaped distortion in the aggregate part and flat fracture surface in the matrix part. There is no obvious crack in the interfacial transition zone (ITZ) due to the weakening of the water wedge effect.

Self-Esteem and Loneliness as Predicting Factors of Arab Children Achievement İn Kuala Lumpur

2015 ◽  
Vol 5 (1) ◽  
pp. 199 ◽  
Author(s):  
Asma'a Abdel Fattah Alhoot ◽  
Ssekamanya Sıraje Abdallah
Keyword(s):  
Academic Achievement ◽  
Relevant Literature ◽  
Self Esteem ◽  
Kuala Lumpur ◽  
Arab Children ◽  
Predicting Factors ◽  
Two Factors ◽  
Arab Schools ◽  
And Gender ◽  
The Impact

Taking into consideration the fact that self-esteem and loneliness have an even more important role to play in students' learning, this study seeks to examine the correlation of these two factors with children academic performance. The study involved 499 (grade 4 to grade 9) Arab children studying at Arab schools in Kuala Lumpur-Malaysia. Data were collected via two questionnaires (one for loneliness and the other for self-esteem). The correlational data analysis yielded a negative correlation between loneliness and academic achievement while there is a positive correlation between self-esteem and achievement. Results also suggested that there is no correlation between students' gender, age, and academic achievement. Furthermore, the results revealed that self-esteem is a good predictor of achievement while loneliness and gender are not good predictors. The findings of the present study are discussed in relation to the relevant literature, taking into consideration the impact of children mental health on their academic achievement. Finally, recommendations for further research are presented.

THE IMPACT OF SERVICE QUALITY ON BRAND LOYALTY OF DTAC SELULER SERVICE USERS

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
Debby Arisandi
Keyword(s):  
Service Quality ◽  
Customer Service ◽  
Service Provider ◽  
Brand Loyalty ◽  
Service Industry ◽  
Positive Impact ◽  
Relevant Literature ◽  
Field Research ◽  
Main Research ◽  
The Impact

<p>Purpose- In the GSM seluler telephony sector, the main condition for protecting the subscriber base is to win customer to be loyalty, a key necessity for the maintenance of a brand loyalty in the long term. To achieve this aim, service quality must be measured and identified. This paper’s aim is to measure the effects of service quality towards brand loyalty on DTAC seluler service provider. This study will explore the relationship between service quality and brand loyalty in the seluler service industry.</p><p>Design/methodology/approach- The main research target sample covered 200 seluler phone users in Prince of Songka University, Hatyai campus. Field research was conducted. The questionnaire was formed by a synthesis of existing constructs in relevant literature. Reliability tests, descriptive statistic, and regressions analyses were performed to both confirm scale reliability and answer the research questions. The data were analysed by moderated regression analysis to test the hypotheses.</p><p>Findings- The findings of this study show that an overall service quality directly affects brand loyalty. Network quality, customer service, pricing structure and billing system are the service quality dimensions that have significant positive influence on brand loyalty, which in turn has a significant positive impact on brand loyalty 43,5%. Therefore, it plays a crucial role in winning customer loyalty.</p><p>Originality/value- It is of great importance for seluler operators in a mature market such as that of Thailand, to understand what the drivers of brand loyalty are. The present study produced useful findings, which can be utilized by seluler service provider managers, in their effort to develop and implement successful brand loyalty strategies. With respect to the findings, pricing structure has the most importance than others dimensions of service quality which provides positive outcomes on brand loyalty, not only in the present but also in the future. So, the effect of pricing structure on brand loyalty becomes greater than the effect of others dimenstions of service quality. Therefore, any GSM operator who wishes to preserve its existing subscriber base should concentrate on winning its subscribers’ loyalty, especially for DTAC.</p>Keywords- Seluler Services, Brand Loyalty, Service Quality

scholarly journals Does Social Support Affect the Health of the Elderly in Rural China? A Meta-Analysis Approach

2019 ◽  
Vol 16 (18) ◽  
pp. 3471 ◽  
Author(s):  
Natuya Zhuori ◽  
Yu Cai ◽  
Yan Yan ◽  
Yu Cui ◽  
Minjuan Zhao
Keyword(s):  
Social Support ◽  
Rural Areas ◽  
Rural China ◽  
Statistical Significance ◽  
Empirical Studies ◽  
Relevant Literature ◽  
The Elderly ◽  
Significant Difference ◽  
Meta Regression ◽  
The Impact

As the trend of aging in rural China has intensified, research on the factors affecting the health of the elderly in rural areas has become a hot issue. However, the conclusions of existing studies are inconsistent and even contradictory, making it difficult to form constructive policies with practical value. To explore the reasons for the inconsistent conclusions drawn by relevant research, in this paper we constructed a meta-regression database based on 65 pieces of relevant literature published in the past 25 years. For more valid samples to reduce publication bias, we also set the statistical significance of social support to the health of the elderly in rural areas as a dependent variable. Finally, combined with multi-dimensional social support and its implications for the health of the elderly, meta-regression analysis was carried out on the results of 171 empirical studies. The results show that (1) subjective support rather than objective support can have a significant impact on the health of the elderly in rural areas, and there is no significant difference between other dimensions of social support and objective support; (2) the health status of the elderly in rural areas in samples involving western regions is more sensitive to social support than that in samples not involving the western regions; (3) among the elderly in rural areas, social support for the older male elderly is more likely to improve their health than that for the younger female elderly; and (4) besides this, both data sources and econometric models greatly affect the heterogeneity of the effect of social support on the health of the elderly in rural areas, but neither the published year nor the journal is significant. Finally, relevant policies and follow-up studies on the impact of social support on the health of the elderly in rural areas are discussed.

scholarly journals Model of thermal buoyancy in cavity-ventilated roof constructions

2021 ◽  
pp. 174425912098418
Author(s):  
Toivo Säwén ◽  
Martina Stockhaus ◽  
Carl-Eric Hagentoft ◽  
Nora Schjøth Bunkholt ◽  
Paula Wahlgren
Keyword(s):  
Analytical Model ◽  
Flow Rate ◽  
Numerical Study ◽  
Air Flow ◽  
Wind Pressure ◽  
Air Flow Rate ◽  
Test Set ◽  
Air Cavity ◽  
Thermal Buoyancy ◽  
The Impact

Timber roof constructions are commonly ventilated through an air cavity beneath the roof sheathing in order to remove heat and moisture from the construction. The driving forces for this ventilation are wind pressure and thermal buoyancy. The wind driven ventilation has been studied extensively, while models for predicting buoyant flow are less developed. In the present study, a novel analytical model is presented to predict the air flow caused by thermal buoyancy in a ventilated roof construction. The model provides means to calculate the cavity Rayleigh number for the roof construction, which is then correlated with the air flow rate. The model predictions are compared to the results of an experimental and a numerical study examining the effect of different cavity designs and inclinations on the air flow rate in a ventilated roof subjected to varying heat loads. Over 80 different test set-ups, the analytical model was found to replicate both experimental and numerical results within an acceptable margin. The effect of an increased total roof height, air cavity height and solar heat load for a given construction is an increased air flow rate through the air cavity. On average, the analytical model predicts a 3% higher air flow rate than found in the numerical study, and a 20% lower air flow rate than found in the experimental study, for comparable test set-ups. The model provided can be used to predict the air flow rate in cavities of varying design, and to quantify the impact of suggested roof design changes. The result can be used as a basis for estimating the moisture safety of a roof construction.

Yoga and Wellness—Key Insights from the Study on General Yoga Programme

2021 ◽  
Vol 14 (1) ◽  
pp. 51-63
Author(s):  
Rabindra Acharya ◽  
Gopal P. Mahapatra ◽  
Kadamibini Acharya
Keyword(s):  
Relevant Literature ◽  
Health And Wellness ◽  
Human Beings ◽  
Recent Past ◽  
Facilitative Role ◽  
Quality Of Living ◽  
The Impact ◽  
Simplified Form

Human beings have always strived towards excellence and progress since time immemorial. Industrialisation, automation and technological disruptions have led to increased comfort and quality of living of human beings and enhanced output, productivity and efficiency. Consequently, of late, health and wellness are receiving increased attention globally. Stress and stress-related diseases and workplace-related ailments have significantly increased over the last few decades and gained attention from society and industrial organisations. In the recent past, in the coronavirus pandemic context, wellness has been focused upon in many countries, communities and organisations worldwide. Yoga has been part of the Indian ethos for centuries. In this article, the authors discuss the General Yoga Programme (GYP), its broad coverage, and the impact it has had on the participants in terms of their wellness. With the help of a survey of the participants and linking it to relevant literature and research in the field, the authors highlight how GYP is a useful tool for enhancing various wellness dimensions. They recommend that GYP in its simplified form can be extended to the workplace; and also, HR professionals can play a facilitative role in the process.

scholarly journals Digital Addiction: Systematic Review of Computer Game Addiction Impact on Adolescent Physical Health

Electronics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 996
Author(s):  
Norshakirah Aziz ◽  
Md Jan Nordin ◽  
Said Jadid Abdulkadir ◽  
Muhammad Muhaimin M. Salih
Keyword(s):  
Physical Health ◽  
Computer Games ◽  
Relevant Literature ◽  
Primary Objective ◽  
Extensive Literature ◽  
Literature Study ◽  
Computer Gaming ◽  
Digital Addiction ◽  
The Impact ◽  
Malaysian Adolescents

The advancement of technology has enabled powerful microprocessors to render high-quality graphics for computer gaming. Despite being intended for leisure purposes, several components of the games alongside the gamer’s environmental factors have resulted in digital addiction (DA) towards computer games such as massively multiplayer online games (MMOG). Excessive gaming among adolescents has various negative impacts on an individual. However, only a few researchers have addressed the impact of DA on physical health. Thus, the primary objective of this research is to study the impact of DA on physical health among Malaysian adolescents. This study focuses on Malaysian adolescents of ages 12–18 years old who are addicted to computer games, specifically the MMOG. The methodology used for the study involves focus group discussions (FGD) and extensive literature study. The FGD sessions have involved both medical experts and game experts. The outcome of FGD discussion is recorded and justified with the existing relevant literature from high-impact journals, theses, conferences, books, and reports. This paper provides evidence of five physical health impacts of DA associated with adolescents. The factors of DA, the addiction components existing in MMOG computer games, and the DA health risk assessment are presented in the results section. Based on the study, it is concluded that DA among Malaysian adolescents can cause various impacts on physical health such as obesity, back pain, and neck pain, orthopaedic/joint muscle, eyesight problem, hearing problem, as well as physical inactivity.

scholarly journals Conversations about FGM in primary care: a realist review on how, why and under what circumstances FGM is discussed in general practice consultations

BMJ Open ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. e039809
Author(s):  
Sharon Dixon ◽  
Claire Duddy ◽  
Gabrielle Harrison ◽  
Chrysanthi Papoutsi ◽  
Sue Ziebland ◽  
...  
Keyword(s):  
Primary Care ◽  
Grey Literature ◽  
Relevant Literature ◽  
Theory Development ◽  
Realist Review ◽  
Primary Outcome Measure ◽  
Mandatory Reporting ◽  
Programme Theory ◽  
Genital Mutilation ◽  
The Impact

ObjectivesLittle is known about the management of female genital mutilation (FGM) in primary care. There have been significant recent statutory changes relevant to general practitioners (GPs) in England, including a mandatory reporting duty. We undertook a realist synthesis to explore what influences how and when GPs discuss FGM with their patients.SettingPrimary care in England.Data sourcesRealist literature synthesis searching 10 databases with terms: GPs, primary care, obstetrics, gynaecology, midwifery and FGM (UK and worldwide). Citation chasing was used, and relevant grey literature was included, including searching FGM advocacy organisation websites for relevant data. Other potentially relevant literature fields were searched for evidence to inform programme theory development. We included all study designs and papers that presented evidence about factors potentially relevant to considering how, why and in what circumstances GPs feel able to discuss FGM with their patients.Primary outcome measureThis realist review developed programme theory, tested against existing evidence, on what influences GPs actions and reactions to FGM in primary care consultations and where, when and why these influences are activated.Results124 documents were included in the synthesis. Our analysis found that GPs need knowledge and training to help them support their patients with FGM, including who may be affected, what needs they may have and how to talk sensitively about FGM. Access to specialist services and guidance may help them with this role. Reporting requirements may complicate these conversations.ConclusionsThere is a pressing need to develop (and evaluate) training to help GPs meet FGM-affected communities’ health needs and to promote the accessibility of primary care. Education and resources should be developed in partnership with community members. The impact of the mandatory reporting requirement and the Enhanced Dataset on healthcare interactions in primary care warrants evaluation.PROSPERO registration numberCRD42018091996.

Sign in / Sign up

Export Citation Format

Share Document