The emission properties, structure and stability of ionic liquid menisci undergoing electrically assisted ion evaporation

The properties and structure of electrically stressed ionic liquid menisci experiencing ion evaporation are simulated using an electrohydrodynamic model with field-enhanced thermionic emission in steady state for an axially symmetric geometry. Solutions are explored as a function of the external background field, meniscus dimension, hydraulic impedance and liquid temperature. Statically stable solutions for emitting menisci are found to be constrained to a set of conditions: a minimum hydraulic impedance, a maximum current output and a narrow range of background fields that maximizes at menisci sizes of 0.5–3 ${\rm \mu}{\rm m}$ in radius. Static stability is lost when the electric field adjacent to the electrode that holds the meniscus corresponds to an electric pressure that exceeds twice the surface tension stress of a sphere of the same size as the meniscus. Preliminary investigations suggest this limit to be universal, therefore, independent of most ionic liquid properties, reservoir pressure, hydraulic impedance or temperature and could explain the experimentally observed bifurcation of a steady ion source into two or more emission sites. Ohmic heating near the emission region increases the liquid temperature, which is found to be important to accurately describe stability boundaries. Temperature increase does not affect the current output when the hydraulic impedance is constant. This phenomenon is thought to be due to an improved interface charge relaxation enhanced by the higher electrical conductivity. Dissipated ohmic energy is mostly conducted to the electrode wall. The higher thermal diffusivity of the wall versus the liquid, allows the ion source to run in steady state without heating.

Optimized Robotic WAAM

This chapter summarizes a PhD thesis introducing a methodology for optimizing robotic MIG (metal inert gas) to perform WAAM (wire and arc additive manufacturing) without using machines equipped with CMT (cold metal transfer) technology. It tries to find the optimal MIG parameters to make WAAM using a welding robot feasible production technique capable of making functional products with proper mechanical properties. Some experiments were performed first to collect data. Then NN (neural network) models were created to simulate the MIG process. Then different optimization techniques were used to find the optimal parameters to be used for deposition. These results were practically tested, and the best one was selected to be used in the third stage. In the third stage, a block of metal was deposited. Then samples were cut from deposited blocks in two directions and tested for tension stress. These samples were successful. They showed behavior close to base alloy.

An Evaluation of Stress Levels in Professionals Performing Work from Home in it Industry during COVID-19 Pandemic

Background: Stress is a feeling that comes from emotional and physical tension. Stress can come from any thought that makes you feel sad, angry or nervous. It is a natural feeling of not being able to cope with specific demands and events. Stress is your body’s reaction to a challenge or demand. Negative responses to challenges can have an adverse effect on the health and happiness of the person who is undergoing stress. IT industry is a filed that poses lot of stress on the workers due to the peer pressures, working hours and work stress. Aim: The aim of this study is to evaluate the stress among IT professionals who are working from home. Materials and Methods: The study design involves a cross-sectional study was done among IT professionals to evaluate the stress among IT professionals who are undergoing work from home admist the COVID- 19 Pandemic situation (6 months duration). A study involved a self-developed questionnaire consisting of 27 questions to assess the stress level of IT people working in IT industry for more than 2 years. This questionnaire was circulated in Google forms and 137 people responded for the survey, out of which 123 participants were undergoing work from home. Results: Out of 137 study participants, 18.25% of them were female and 81.75% of them were male. 25.55% participants were of age group 18 - 35 and 74.45% participants were of age group 35 -50. 90.51% participants are IT professionals and out of those 86.86% of participants are doing work from home. 72.26% of the participants feel that they are stressed too much due to work from home, and 27.47% of the participants feel that they are not that much stressed due to work from home. 45.99% of participants are more stressed, 28.47% of them are moderately stressed, 13.14% of them are lightly stressed and 12.41% of them are not stressed. Conclusion: Thus, the study concluded an innovative finding that IT professionals experienced severe stress due to high peer pressures, home environments and were more prone to psychosomatic disorders.

Portable universal tensile testing machine for studying mechanical properties of superelastic biomaterials

A portable universal tensile testing machine for single and cyclic loading of superelastic biomaterials is presented. It’s an alternative to large-sized stationary universal testing machines. The machine is designed to obtain uniaxial cyclic tension stress-strain curves of materials with a low elastic modulus, including biological tissues. Its portability allows using it in various conditions: classrooms, production laboratories, and in the field. An interface has been developed to connect it to a computer. Computer output of experimental data allows recording and displaying load-displacement curves, setting the number of cycles, limits, and rate of cyclic deformation. Several examples of testing various biomaterials are presented. The functional advantage of the device is the wide tensile testing speed range of 0.01-10 mm/s and cyclic loading, which allow capturing viscoelastic and superelastic behavior of biomaterials.

Explanatory Models of Depression in a Rural Community of Coastal Karnataka, India: A Cross-Sectional Survey

Background: Depression is a major public health problem but there is a huge treatment gap in India. Cultural beliefs influence conception of illness, personal meaning, help-seeking behaviors, and adherence to treatment. Research on explanatory models of depression attempt to explore these unique characteristics in an individual and the community. We set out to examine explanatory models of depression in a rural community of coastal Karnataka and explore the association between sociodemographic variables and explanatory models of depression. Methods: A cross-sectional household survey in the rural community of Harekala village, Mangaluru taluk, Dakshina Kannada district, Karnataka, was done using Kish tables. A total of 200 individuals were interviewed with an adaptation of the Short Explanatory Model Interview in a local language using a case vignette of depression. Results: Around 40% of the individuals perceived the problem as tension/stress/excessive worrying and did not perceive it as mental illness. A scant 10% of the participants recognized some mental illness. Around one-fifth of the individuals attributed the problem to evil spirits and black magic; female participants were more likely to endorse consulting a doctor (P = 0.003**) or a psychiatrist (P = 0.012*). In addition, participants belonging to Islam were less likely to consult a doctor (P = 0.028*) and psychiatrist (P = 0.021*). Also, participants belonging to lower social class were less likely to endorse psychiatric consultation (P = 0.018*) Conclusions: A vast majority of the study subjects failed to identify depression as an illness or acknowledge biomedical causation. Gender, religion, and socioeconomic class may influence help-seeking behavior.

Monitoring of stress variation of strands in prestressed concrete by second harmonic generation measurements based on piezoelectric sensors

The stress loss of prestressed concrete may cause the ultimate failure of structures and the monitoring of stress variation of prestressed structures is therefore important to ensure the service safety. This paper developed a nondestructive evaluation (NDE) method of nonlinear ultrasonic second harmonic generation (SHG) based on piezoelectric (PZT) sensors and applied for the distinction of different stress level of post-tensioned steel strands in concrete. The nonlinear ultrasonic behavior of both free strand and embedded strand having different length is studied with the developed SHG technique and a defined nonlinear parameter is introduced in SHG experiments to correlate with the tension stress in the strand. It is found that the nonlinear parameter has a negative correlation with the increasing stress of strand in both free and embedded case, indicating the nonlinear ultrasonic behavior is getting weak corresponding to the increasing contact force among strand wires. In addition, the decreasing ratio of nonlinear parameter is very close to each other regardless of the length of steel strand, indicating the possibility of replacing the large-scale on-site testing with scaled down samples in laboratory. The experimental results of this research demonstrate that the SHG technique based on PZT sensors could be useful for the stress monitoring of prestressed reinforced concrete with consideration of the relatively high sensitivity of nonlinear parameter to the variation of contact force of strand wires.

MODELING OF SCHEMES OF CRACK DEVELOPMENT IN SHAPE SHELLS BASED ON TRAJECTORIES OF THE LARGEST TENSION STRESS

В статье для пологой оболочки, загруженной равномерно распределенной нагрузкой, со схемой опирания на шарнирные опоры получено аналитическое решение. Нагрузка и неизвестные функции прогиба и напряжений представлены с помощью двойных тригонометрических рядов. Выполнены расчеты напряженно-деформированного состояния, определены усилия и перемещения. Дана оценка точности суммирования рядов по перемещениям и усилиям. В окрестности точек нижней, срединной и верхней поверхностей оболочки вычислены нормальные и касательные напряжения, а также главные напряжения и главные площадки. Показана картина двухосного напряженного состояния и на ее основе построены графики траекторий наибольших растягивающих напряжений. Графики траекторий на нижней поверхности оболочки сопоставлены с экспериментальными схемами развития трещин. По траекториям наибольших растягивающих напряжений, построенных в точках нижней поверхности, делается прогноз о месте, направлении и последовательности появления трещин в оболочке. An analytical solution is obtained in the article for a shallow shell loaded with a uniformly distributed load, with a scheme of bearing on hinged supports. Load and unknown deflection and stress functions are represented using double trigonometric series. Calculations of the stress-strain state were performed, forces and displacements were determined. An assessment of the accuracy of summation of the series of displacements and efforts is given. In the vicinity of the points of the lower, middle and upper surfaces of the shell, normal and shear stresses, as well as principal stresses and principal areas, are calculated. The picture of the biaxial stress state is shown and on its basis, the graphs of the trajectories of the highest tensile stresses are constructed. The trajectory plots on the lower surface of the shell are compared with the experimental crack propagation schemes. The trajectories of the highest tensile stresses plotted at the points of the lower surface are used to predict the location, direction, and sequence of cracks in the shell.

Factors Associated with Intention of Serbian Public Health Workers to Leave Their Job: A Cross-Sectional, Population-Based Study

Recruitment and retention of public health workers (PHWs) is crucial for the optimal functioning of the public health system at a time of budget cuts and the threat of a pandemic. Individual and job-related variables were examined by univariate and multivariate logistic regression to identify predictors of the intention to leave a job during the COVID-19 outbreak among Serbian PHWs in 25 institutes of public health (n = 1663 respondents, of which 73.1% were female). A total of 20.3% of PHWs intended to leave their current job within the next five years. Males and persons aged younger than 55 years who had additional practice were more likely to report an intention to leave their job than females, those older than 54 years and those without additional work. While uncertainty and fear of infection during the COVID-19 pandemic were almost perceived as job attractiveness, other job-related characteristics were identified as significant barriers to maintaining the sufficient capacity of qualified PHWs in the future. Authorities need to address these factors, including the following: the feeling of tension, stress or pressure, and unavailability of information during the COVID-19 pandemic, as well as dissatisfaction with respect, valuation, and the job in general.