Tractor ballasting in field transport work

The article presents the investigation of the interaction of tractor traction force, mass, trailer and tractor mass ratio and wheel slippage. The analysis of the influence of ballast weight and wheel slippage on the fuel consumption under various field and road conditions was carried out. Wheel slippage dependence on the pull force, a weight force utilization coefficient and ratio of the mass of a trailer and tractor were stated and analyzed. The nomogram for operative selection of the optimal ballast weight and its location place is presented when instantaneous wheel slippage is known. The nomogram consists of three parts. In the lower part dependence d=f(mp/m), (wheel slippage on the ratio of the mass of a trailer and tractor) is placed. In the middle part there is dependence of the tractor mass m made of the expression of the wheel grip weight force utilization coefficient jg=Ft/G on the ratio of the mass of a trailer and tractor m=f(mp/m).The upper part is designed for dependence Dmp=f(mp)(transferred mass of tractor Dmp on the rear wheels on the mass trailer mp. The bottom part of the nomogram is connected with the middle part by the common abscissa axle on which the ratio of the mass of a trailer and tractor is placed. The curves of the middle part of the nomogram m=f(mp/m)are connected with the analogical concrete mass trailer values mp, placed in the abscissa axle by intermediate lines

Analysis of main dynamic parameters of split power transmission

The review carried out had shown one basic approach of split power transmission to the organization of drive which is applied to stepless transmissions of tractors and parallel hybrid cars. In the split power transmission the power split device uses a planetary gear. Tractor engine power in the split power transmission is transmitted to the drive shaft via a mechanical and hydraulic path. The theoretical analysis of main parameters of the split power transmission of the tractor is presented. The angular velocity of sun and coronary gears of the differential set is estimated by solution of the system of equations in which one equation is made for planetary differential gear, and another – for hydrostatic drive. The analysis of the transmission gear-ratio dependencies on the ratio of hydraulic machines capacities is carried out. Dependence of the variation of angular velocity of the coronary and the sun gears on the ground speed of the tractor is presented. Dependence of sum shaft torque and its constituents, carried by mechanical and hydraulic lines, on sum shaft angular velocity and ground speed of tractor and engine speed is also presented

Self-Harm in Children and Adolescents Who Presented at Emergency Units During the COVID-19 Pandemic: An International Retrospective Cohort Study

Objective: To compare psychiatric emergencies and self-harm at emergency departments (EDs) one year into the pandemic, to early pandemic and pre-pandemic, and to examine the changes in the characteristics of self-harm presentations. Method: This retrospective cohort study expanded on the Pandemic-Related Emergency Psychiatric Presentations (PREP-kids) study. Routine record data in March-April of 2019, 2020, and 2021 from 62 EDs in 25 countries were included. ED presentations made by children and adolescents for any mental health reasons were analyzed. Results: Altogether, 8174 psychiatric presentations were recorded (63.5% female; mean [SD] age, 14.3 [2.6] years), 3742 of which were self-harm presentations. Rate of psychiatric ED presentations in March-April 2021 was twice as high as March-April 2020 (IRR, 1.93; 95% CI, 1.60-2.33), and 50% higher than March-April 2019 (IRR, 1.51; 95% CI, 1.25-1.81). Rate of self-harm presentations doubled between March-April 2020 and March-April 2021 (IRR, 1.98; 95% CI, 1.68-2.34), and overall 1.7 times higher than March-April 2019 (IRR, 1.70; 95% CI, 1.44-2.00). Comparing self-harm characteristics in March-April 2021 with March-April 2019, self-harm contributed to a higher proportion of all psychiatric presentations (OR, 1.30; 95% CI, 1.05-1.62), whilst female representation in self-harm presentations doubled (OR, 1.98; 95% CI, 1.45-2.72) and follow-up appointments were offered four times as often (OR, 4.46; 95% CI, 2.32-8.58). Conclusion: Increased pediatric ED visits for both self-harm and psychiatric reasons were observed, suggesting potential deterioration in child mental health. Self-harm in girls possibly increased and needs to be prioritized. Clinical services should continue utilizing follow-up appointments to support discharge from EDs. Diversity & inclusion statement: One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group. While citing references scientifically relevant for this work, we also actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our reference list. The author list of this paper includes contributors from the location and/or community where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the wor

Self-Harm in Children and Adolescents who Presented at Emergency Units During the COVID-19 Pandemic: An International Retrospective Cohort Study

Objective: To compare psychiatric emergencies and self-harm at emergency departments (EDs) 1 year into the pandemic, to early pandemic and pre-pandemic, and to examine the changes in the characteristics of self-harm presentations. Method: This retrospective cohort study expanded on the Pandemic-Related Emergency Psychiatric Presentations (PREP-kids) study. Routine record data in March to April of 2019, 2020, and 2021 from 62 EDs in 25 countries were included. ED presentations made by children and adolescents for any mental health reasons were analyzed. Results: Altogether, 8,174 psychiatric presentations were recorded (63.5% female; mean [SD] age, 14.3 [2.6] years), 3,742 of which were self-harm presentations. Rate of psychiatric ED presentations in March to April 2021 was twice as high as in March to April 2020 (incidence rate ratio [IRR], 1.93; 95% CI, 1.60-2.33), and 50% higher than in March to April 2019 (IRR, 1.51; 95% CI, 1.25-1.81). Rate of self-harm presentations doubled between March to April 2020 and March to April 2021 (IRR, 1.98; 95% CI, 1.68-2.34), and was overall 1.7 times higher than in March to April 2019 (IRR, 1.70; 95% CI, 1.44-2.00). Comparing self-harm characteristics in March to April 2021 with March to April 2019, self-harm contributed to a higher proportion of all psychiatric presentations (odds ratio [OR], 1.30; 95% CI, 1.05-1.62), whereas female representation in self-harm presentations doubled (OR, 1.98; 95% CI, 1.45-2.72) and follow-up appointments were offered 4 times as often (OR, 4.46; 95% CI, 2.32-8.58). Conclusion: Increased pediatric ED visits for both self-harm and psychiatric reasons were observed, suggesting potential deterioration in child mental health. Self-harm in girls possibly increased and needs to be prioritized. Clinical services should continue using follow-up appointments to support discharge from EDs. Diversity & inclusion statement: One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group. While citing references scientifically relevant for this work, we also actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our reference list. The author list of this paper includes contributors from the location and/or community where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the work