Volume/shear work ratio influence on wear and stress of soil chisel tine modelled by DEM

2021 ◽  
pp. 135065012110582
Author(s):  
Egidijus Katinas ◽  
Rostilav Choteborsky
Keyword(s):  
High Stress ◽  
Wear Intensity ◽  
Tool Geometry ◽  
Soil Conditions ◽  
Agricultural Equipment ◽  
Wear Analysis ◽  
Preparation Period ◽  
Soil Preparation ◽  
Soil Bin ◽  
Very High

Agricultural equipment is working in very high-stress conditions. However, it has a significant influence on the wear losses of soil processing parts. Chisel is operating at 30 cm working depth at a maximum of 12 km·h−1 working speed. Due to unpredictable soil conditions, chisel tines suffer high wear losses. It leads to time consumption and cost expenses during the soil preparation period. Wear resistance, and agronomical requirements (working depth, loosening of soil) are the main criteria of agricultural equipment producers. The discrete element method is a solution that simulates soil as sphere shape particles with soil properties. Wear results reveal the change of parts shape, acting forces, and stresses during the simulation in the virtual soil bin. The used Rocky DEM software uses a parameter C (volume/shear work ratio) to describe wear intensity, which varies for different geometry. Chisel tine geometry should be divided into sections with varied parameter C according to stress acting on the surface. The test conditions can be used for future wear analysis of varied tool geometry and protection (sintered tungsten carbide plates, hard-faced surface, etc.) agricultural tools to compare its durability in different soil conditions.

scholarly journals General-Purpose Forest Plough

2017 ◽  
Vol 7 (3) ◽  
pp. 193-200
Author(s):  
Иван Бартенев ◽  
Ivan Bartenev ◽  
Михаил Лысыч ◽  
Mikhail Lysych ◽  
Михаил Шабанов ◽  
...  
Keyword(s):  
High Efficiency ◽  
General Purpose ◽  
Soil Conditions ◽  
High Survival ◽  
Modular Construction ◽  
Soil Preparation ◽  
Waterlogged Soils ◽  
Low Efficiency ◽  
Single Instrument ◽  
Specific Amount

The basic soil preparation is an important factor in ensuring high survival rate and preservation of cultural plants. Its objective is to loosen the soil to a predetermined depth, it is also important to ensure the containment of weeds growth in areas, adjacent to the row of crop strips. Depending on soil conditions it may be cutting of one or double earthboard furrows (drained soil) and in the formation of microhill (temporarily waterlogged soils). For these purposes, currently, ploughs PKL-70, PRL-70, PL-1, PLM-1.5A, PDV-1.5, PL-2-50, PLD-1.2, etc. are used. Their common drawback is the ability to perform only one operation. A large variety of used tillage equipment and its low efficiency confirms the urgency of developing multi-tools modular construction. This will effectively produce basic preparation of the soil in a variety of conditions with a single instrument. The article provides a description of design and basic layout options of multifunctional plough. By simple changeovers, carried out on site, the plough can be adapted for the main preparation of soil on clearings with drained and temporarily waterlogged soils. It is also possible to change the distance between the bodies of the plow in accordance with the specified rows and rearrange them to work "in" or "out". Process works is modeled in conditions of non-uprooted cutting. The simulation experiment showed high efficiency of the plough, which is ensured by the presence of safety recoverable devices. Replacement in the forestry enterprise of a set of ploughs with one multipurpose plough will reduce total specific amount of metal almost in 4 times.

scholarly journals The major worldwide stress of healthcare professionals during the first wave of the COVID-19 pandemic – the international COVISTRESS survey

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0257840
Author(s):  
Sébastien Couarraze ◽  
Louis Delamarre ◽  
Fouad Marhar ◽  
Binh Quach ◽  
Jiao Jiao ◽  
...  
Keyword(s):  
Healthcare Workers ◽  
Protective Factor ◽  
Healthcare Professionals ◽  
High Stress ◽  
Medical Doctors ◽  
Health Crisis ◽  
Paramedical Staff ◽  
Increased Risk ◽  
Stress Levels ◽  
Very High

Introduction The COVID-19 pandemic has initiated an upheaval in society and has been the cause of considerable stress during this period. Healthcare professionals have been on the front line during this health crisis, particularly paramedical staff. The aim of this study was to assess the high level of stress of healthcare workers during the first wave of the pandemic. Materials and methods The COVISTRESS international study is a questionnaire disseminated online collecting demographic and stress-related data over the globe, during the pandemic. Stress levels were evaluated using non-calibrated visual analog scale, from 0 (no stress) to 100 (maximal stress). Results Among the 13,537 individuals from 44 countries who completed the survey from January to June 2020, we included 10,051 workers (including 1379 healthcare workers, 631 medical doctors and 748 paramedical staff). The stress levels during the first wave of the pandemic were 57.8 ± 33 in the whole cohort, 65.3 ± 29.1 in medical doctors, and 73.6 ± 27.7 in paramedical staff. Healthcare professionals and especially paramedical staff had the highest levels of stress (p < 0.001 vs non-healthcare workers). Across all occupational categories, women had systematically significantly higher levels of work-related stress than men (p < 0.001). There was a negative correlation between age and stress level (r = -0.098, p < 0.001). Healthcare professionals demonstrated an increased risk of very-high stress levels (>80) compared to other workers (OR = 2.13, 95% CI 1.87–2.41). Paramedical staff risk for very-high levels of stress was higher than doctors’ (1.88, 1.50–2.34). The risk of high levels of stress also increased in women (1.83, 1.61–2.09; p < 0.001 vs. men) and in people aged <50 (1.45, 1.26–1.66; p < 0.001 vs. aged >50). Conclusions The first wave of the pandemic was a major stressful event for healthcare workers, especially paramedical staff. Among individuals, women were the most at risk while age was a protective factor.

scholarly journals Identification of Soils Factors Influence in the Distributions of Tuber aestivum in Transylvanian Subcarpathian Hill, Romania

2018 ◽  
Vol 47 (2) ◽  
pp. 478-486 ◽  
Author(s):  
Horea PĂCURAR ◽  
Marcel DÎRJA ◽  
Mihai BUTA ◽  
Ioan PĂCURAR ◽  
Sanda ROȘCA ◽  
...  
Keyword(s):  
Spatial Analysis ◽  
Field Research ◽  
High Price ◽  
Soil Conditions ◽  
Tuber Aestivum ◽  
Black Truffle ◽  
Frequent Use ◽  
Bivariate Statistical Analysis ◽  
Black Truffles ◽  
Very High

Truffles are one of the most hunted varieties of mushrooms in Europe due to their high price and their increasingly frequent use in the kitchen. As demonstrated by several studies, soil conditions are among the main factors that influence the spread and development of the black truffle species. The purpose of this study was to identify the soil factors which directly and indirectly influence the distribution of black truffles (Tuber aestivum Vittad.) in Romania and to identify the areas from the Subcarpathian Hills of Transylvania which are highly favourable to their existence and growth, using G.I.S. spatial analysis and databases which include soil characteristics (soil type, texture, gleization, stagno-gleization) and territorial localisation through GPS points indicating the samples of Tuber aestivum. By implementing the statistical model of spatial analysis (BSA – Bivariate Statistical Analysis) for each characteristic, a series of areas were classified into three classes of favourability (low, medium, high) for the growth of Tuber aestivum. The results were validated indirectly by comparing the overlapping of the areas from the high favourability class with the areas covered with tree species from the Quercus genus and directly, through field research (on the surfaces with maximum favourability), done by specialised truffle seekers. The results were validated with a very high confidence rate for both methods (method 1 - overlapping of approximatively 93%, method 2 - Tuber aestivum was identified on 12 out of 15 test surfaces from the high favourability class).

scholarly journals Stress and Coping Mechanism of Infertile Women Attending Infertility Clinic in Kathmandu

2015 ◽  
Vol 2 (4) ◽  
pp. 24-28 ◽  
Author(s):  
Chandrakala Sharma ◽  
D Subedi ◽  
L Rai ◽  
K Upreti
Keyword(s):  
Coping Strategies ◽  
Religious Coping ◽  
High Stress ◽  
Structured Interview ◽  
Stress And Coping ◽  
Coping Mechanism ◽  
Infertile Women ◽  
High Level ◽  
And Coping ◽  
Very High

INTRODUCTION: Many women face problems related to infertility in various aspects of their life. Also, it is not comfortable to discuss on this issue. Because of this, the feelings and distress faced by women may not come out and the pent up emotions may lead to different stress related problems.   MATERIAL AND METHODS : A descriptive research design was adopted to assess the stress and coping mechanism of infertile women attending infertility clinic in Kathmandu Nepal. The study was conducted from October 2011 to January 2013. Purposive sampling technique was used and sample size was 100. Data was collected through semi- structured interview using; 'Perceived Stress Scale'(PSS) and 'Coping Check List' (CCL).   RESULTS: Regarding stress level of respondents, 40% were at very high level of stress and 35% with high level of stress. High level stress was found among the age group of 21-30 years. In relation to level of stress and coping strategies, 54.17% respondents with high stress used religious coping strategies, 50% of the respondents with very high stress also used religious coping, followed by 40% emotional coping and 37.5% problem focused coping and seeking social support strategies to overcome the stress.   CONCLUSION: It can be concluded that the  almost more than half of the respondents were under high level of stress and mostly were those who are under  treatment for more than 1-3 yrs of duration. The study also concluded that the higher the age the respondents were more stressed due to the infertility. It was also found that most of the respondents used religious coping as well as emotional focused coping during the stressful period.DOI: http://dx.doi.org/10.3126/jucms.v2i4.12039Journal of Universal College of Medical Sciences (2014) Vol.02 No.04 Issue 08Page: 24-28

The Coning Designs for the Micro Forming of a Surgical Slit Knife Using FE Simulations

2012 ◽  
Vol 197 ◽  
pp. 745-749
Author(s):  
Xin Wu Ma ◽  
Guo Qun Zhao ◽  
Wen Juan Li
Keyword(s):  
Stress Distribution ◽  
High Stress ◽  
Three Dimensional ◽  
Die Geometry ◽  
Strength Limit ◽  
Fe Simulations ◽  
Die Stress ◽  
Die Material ◽  
Forming Defects ◽  
Very High

This paper deals with problems in the coining process for manufacturing surgical slit knife using two-dimensional (2D) and three-dimensional (3D) finite element (FE) simulations. The FE simulations are performed to investigate the material flow, and especially stress distribution on the coining dies. The main objective of this paper is to study the feasibility of a coining process for manufacturing a given geometry of surgical slit knife without forming defects and die failure. Very high stress distribution on the coining dies is found by 2D simulations of the coining process that exceeds the strength limit of the die material. The optimum preform and preforming die geometry are determined by FE simulations in order to reduce the die stress. 3D simulations of the preforming and coining processes are conducted with the optimal design to show that the geometry of the product can be achieved without defects by the coining process.

scholarly journals Influence of waterlogging stress and benzyladenine application on tomato grafted to eggplant

2007 ◽  
pp. 105-118
Author(s):  
Mary Ann Jully Regis ◽  
Misael Diputado
Keyword(s):  
Morphological Changes ◽  
High Stress ◽  
Stomatal Resistance ◽  
Soil Conditions ◽  
Tomato Plants ◽  
Lower Survival Rate ◽  
Waterlogging Stress ◽  
Stress Effects ◽  
As Stress ◽  
Aerobic Soil

Under waterlogged conditions, the non-grafted tomato plants had significantly lower survival rate (53%), compared to the 100% survival rating of grafted plants. Both grafted and non-grafted plants while under waterlogged conditions had high leaf stomatal resistance, low transpiration rate and high stress rating, compared to the non-waterlogged plants. However, one week after resumption of aerobic soil conditions, both stomatal resistance and transpiration as well as stress rating returned to normal in grafted plants unlike in the non-grafted plants which continued to show high stomatal resistance, low transpiration rates and high stress rating. The morphological changes associated with stress in the plant regardless of treatments were cupping, drooping and eventual wilting of leaves. Due to severe stress under waterlogged conditions, the non-grafted plants had significantly lower yield which was just about 41% that in grafted plants. The grafted, non-waterlogged plants had comparable yield with the non-grafted, non-waterlogged plants. Application of benzyladenine was not effective in alleviating waterlogging stress effects on both grafted and non-grafted tomato.

scholarly journals Stress in Teaching: A Summary of a Report by Optum Research

2006 ◽  
Vol 3 (3) ◽  
Author(s):  
Unknown Unknown
Keyword(s):  
Task Performance ◽  
Job Stress ◽  
High Stress ◽  
Related Stress ◽  
High Level ◽  
Job Related Stress ◽  
Very High

According to research published by Optum Research teachers reported that job related stress impacts their on task performance. A survey developed by Optum research revealed that o f the Mid Western teachers who were surveyed four out of ten teachers experience at least a high level of job stress. The survey found that 6 percent of teachers experience very high related job stress, 38 percent experience high stress, 44 percent medium stress and 12 percent very low stress. Researchers found that stress was highest among teachers who reported

scholarly journals PKB Zmaj: A new variety of winter rye created at PKB Agroekonomik institute

2021 ◽  
Vol 27 (1) ◽  
pp. 17-23
Author(s):  
Nenad Đurić ◽  
Dobrivoj Poštić ◽  
Vojin Cvijanović ◽  
Gordana Branković ◽  
Vera Đekić ◽  
...  
Keyword(s):  
Yield Potential ◽  
High Yield ◽  
Soil Conditions ◽  
Late Winter ◽  
Winter Rye ◽  
New Variety ◽  
The Republic ◽  
Very High ◽  
High Adaptation ◽  
High Yield Potential

For the last twenty years, in addition to breeding wheat, PKB Agroekonomik Institute has been working very intensively on breeding other real or bread grains. High-yielding, late winter rye variety PKB Zmaj has been obtained by the pedigree method by a simple crossing of genetically different parents from the collection of PKB Agroekonomik Institute: variety Rtanj and line PKB-R-105. This variety of winter rye combines genes responsible for very high yield potential, resistance to lodging, low temperatures and more significant diseases in the rye. Winter rye variety PKB Zmaj was registered by the Ministry of Agriculture, Forestry and Water Management of the Republic of Serbia in 2018. With the use of optimal agricultural techniques, the variety PKB Zmaj has a high genetic potential for fertility and high adaptation to different climatic and soil conditions.

Behavior of Unstiffened and Stiffened Steel Tubular T-Joints

1989 ◽  
Vol 111 (1) ◽  
pp. 56-60 ◽  
Author(s):  
G. Raghava ◽  
A. G. M. Rao ◽  
D. S. R. Murthy
Keyword(s):  
Stress Concentration ◽  
Stress Gradient ◽  
High Stress ◽  
Vital Role ◽  
Wave Forces ◽  
Tubular Joints ◽  
Abrupt Changes ◽  
Element Technique ◽  
Stiffened Steel ◽  
Very High

Offshore towers standing in deep sea are susceptible to cyclic nature of wave forces. Fatigue failure initiates at the welded tubular joints of these structures where a very high stress gradient and localized stress concentration exist due to abrupt changes in the geometry. Stress concentration plays a vital role in the design of steel tubular joints, as it directly affects the fatigue life of the structures. This paper presents results of an experimental study on the behavior of an unstiffened and a stiffened steel tubular welded T-joint under axial brace loading. The effect of internal ring stiffeners has been studied theoretically and experimentally. In the experimental technique, the specimens were extensively strain-gaged and the stress distribution determined under static load. The analytical results have been obtained by finite element technique.

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