9 research outputs found
Some solutions based on elastic-plastic and creep transition in homogeneous and non-homogeneous shells
No full textElastic-plastic and creep analysis of shell structures have an important role in engineering applications. Engineers have found its increasing application in aerospace, chemical, civil and mechanical industries such as in high-speed centrifugal separators, gas turbines for high-power aircraft engines, spinning satellite structures, certain rotor systems and rotating magnetic shields. To increase the strength of shells, it is therefore very important for engineers to study the behaviour of elastic-plastic and creep transition of shells. A shell is a curved surface, in which the thickness is much smaller than the remaining dimensions. The geometrical properties of shells, i.e. single or double curvature give rise to a tremendous advantage of these light weight structures. The concept of elastic-plastic and creep transition problems is related to the science of forces and motions. The numerical solution of these problems can be achieved through a proper blending of the principles of mechanics with certain postulates and assumptions based on experiments and experience. This study comes under the field of Solid mechanics. The Solid mechanics is the branch of Continuum mechanics that deals with the behaviour of solid materials, especially their motion and deformation under the influence of forces, thermal effects and other different conditions. In order to make a mechanical body safe, a designer must have knowledge of the limiting conditions of stress at which temporary and permanent deformation starts to develop so that danger of yielding or fracture is to be eliminated. Deformations which are recovered after the removal of body forces are called elastic deformations. In this case, a body completely recovers its original configuration. On the other hand, if deformation remains even after body forces have been removed is called plastic deformation. It is one of type of irreversible deformations in which material bodies after stresses have attained a certain threshold value known as the elastic limit or yield stress. If the state of deformation in a body remains constant throughout the whole part of the material body is called homogeneous deformation and the tendency of a solid material to move slowly or deform permanently occur as result of long-term exposure to high level of stress is called creep deformation. Creep deformation does not occur suddenly upon the application of stress. Instead, strain accumulates as a result of long-term stress. Therefore, creep is a "time-dependent" deformation. The ‘theory of elasticity’ has been continuously developed by various investigators for anisotropic bodies and isotropic bodies since 1950. This theory is the solid foundation for the scientists in designing of engineering structures because of its increasing application to engineering problems. In the same manner, the designers are interested in the ‘theory of plasticity. It is helpful in understanding the deformation behaviors for avoiding excessive deflection or distortion in machine parts. In 1868, Tresca considered that there exists a ‘mid-zone’ area between the elastic and plastic regions which is against Saint-Venant’s two-zone theory. Although Tresca’s theory was ignored by later research workers for the sake of convenience. Many authors have not recognized mid zone area as a separate part that of elasticity and plasticity. A many attempts have been made in this direction of intermediate state illustrated by Thomas, Green and Seth. Seth has elaborated the concept of this intermediate region. He has named this region as “Transition region”. He has developed a transition theory of elastic-plastic and creep transitions. Seth has defined the concept of generalized strain measure which when applied to the governing differential equation of the medium eliminates ad-hoc assumptions like incompressibility, creep strain law and yield condition but also employs the same constitutive equations to give elastic-plastic and creep results through some transition functions. The most important contribution to be made by generalized measures is that they do not use of semi-empirical laws and jump conditions unnecessary. Therefore, concept of generalized measure in which two parameters are determined experimentally, give a better idea about creep behaviour.
The classical macroscopic treatment of solving the problems in (i) plasticity, (ii) creep and (iii) relaxation has to assume semi-empirical yield conditions like those of Tresca and von Mises and Creep strain laws like those of Norton, Odquist and others. This is a direct consequence of using linear strain measures which neglect the non-linear transition region through which the yield occurs and the fact that creep and relaxation strains are never linear. Therefore classical elastic-plastic model does take into consideration the non linear part through which transition takes place. Here in this current literature, the problems of elastic -plastic and creep transitions are solved by considering non liner part through which the transition takes place. The transition theory of B.R. Seth is helpful to deal these types of problems. The motive of study is finding the solution of transition problems of shells with the different conditions. The study is helpful to know the conditions under which life of material parts in machines get longer, reducing wearing on mating parts, better mechanical dampening (less noise), faster operation of equipment, less power needed to run equipment, chemical and corrosion resistance etc. Therefore, the scope of study deals with the providing guidelines to designers for making products. It deals in developing new ideas to meet changing demands of products in machinery around the world so that innovative, collaborative spirit between people can be developed. This can lead to the production of industry’s broadest range of engineering materials. By study the nature of transition in spherical shells, one can determine the applications and mechanical requirements of body containing shell.
The whole part of thesis is divided into eight chapters. The first chapter of thesis consists of brief introduction about shells, theory of elasticity, plasticity and creep. The various terms like stress, strain, generalized strain measures, and concept of transition state given by Seth has been discussed. The basic fundamental governing equations are defined in the thesis. The chapter discusses the brief literature review of problems on spherical shells. The chapter also consists of research methodology used in thesis to find the solution of the problems. Further thesis consists of seven more chapters depicting various research problems and their solutions based on elastic-plastic and creep transition. The second chapter deals with problem of “Elastic-plastic stress analysis in a Spherical shell under internal pressure and steady state temperature”. Curves have been drawn between stresses and radii ratio R = r/b for the initial state and fully plastic state. It has been observed that the circumferential stress is the maximum at the external surface. Thermal effect increases the value of circumferential stresses at the outer surface. The spherical shell made of the incompressible material required the higher value of circumferential stresses to start yielding as compared to compressible materials. The third chapter deals with the “Non-homogeneity effect in the spherical shell by using Seth's transition theory”. The effect of non-homogeneity has been discussed numerically and depicted graphically. It is assumed that non-homogeneity varies along the radius of the spherical shell. It has been observed that the spherical shell made of non-homogeneous material requires high pressure to attain fully plastic state from the elastic state as compared to the spherical shell made of homogeneous material. This indicates that spherical shell made of non-homogeneous material is on the safer side of design. The fourth chapter deals with the “Thermal Creep stress and strain analysis in non-homogeneous Spherical shell”. Seth’s transition theory is applied to the problem of creep stresses and strain rates in non-homogeneous spherical shell under steady-state temperature. Neither the yield criterion nor the associated flow rule is assumed here. With the influence of thermal effect, the values of circumferential stress are decrease at the external surface as well as internal surface of the spherical shell for different values of non-homogeneity. The fifth chapter deals with problem of “Elastic-Plastic transition on rotating Spherical shell in dependence of compressibility”. The purpose of paper is to establish the mathematical treatment of elastic-plastic transitions occurring in the rotating spherical shells and to find angular speed required to start yielding in rotating shells for compressible and incompressible materials. The effect of density variation parameter has been discussed numerically and depicted graphically. With the effect of density variation parameter, rotating spherical shells starts yielding at internal surface with the lower values of the angular speed for incompressible/compressible materials. The sixth chapter deals with problem of “Creep transition in the rotating spherical shell under the effect of density variable by Seth’s transition theory". The creep stresses and strain rates have been evaluated with the effect of variable density in a spherical shell. It has been seen that the values of radial/circumferential stresses must be decreased at the internal surface of the spherical shell with the effect of the density variation. This means that the possibility of fracture at the internal surface of the spherical shell decreases with the effect of density variable. The problem in chapter seventh has been discussed in two sections as (i) Elastic-plastic stress analysis of spherical shell under internal and external pressure and (ii) Transition analysis of spherical shell structures under external pressure. The results have been derived numerically and depicted graphically. The effect of the pressure is seen on the radial and circumferential stresses of the spherical shell. The eighth chapter summarizes the salient conclusions of this study. The end chapter also identifies the scope for future work.Navedeni su: supervisor (contributor advisor), committee members (contributor other)
Guarav Verma Regd. No: 1213017
Zapisnik sa sednice NNV, NNV-p12-161
Axisymmetric deformation in a micropolar thermoelastic medium under fractional order theory of thermoelasticity
No full textA two dimensional problem on laser pulse heating in thermoelastic microelongated solid
No full textIn the present discussion, the plane strain deformation due
to laser pulse heating in a thermoelastic microelongated solid has been discussed. The analytic expressions for displacement component, force stress,
temperature distribution and micro-elongation have been derived. The effect of pulse rise time and micro-elongation on the derived components have
been depicted graphically
Non-homogeneity effect in the spherical shell by using seth's theory
No full textThis paper presents nonlinear deformation behaviour of non-homogeneous spherical shell examined under pressure by using Seth's transition theory. It has been seen that for increased material compressibility in thickness direction, the circumferential stress in the spherical shell reaches maximum at the external surface, but is reverse in the case of a deceasing compressibility in the thickness direction. The spherical shell of non-homogeneous material (non-homogeneity increases radially) is on the safer side of design. Hence, the more use of non-homogeneous material (non-homogeneity increases radially) may be beneficial for manufacturing spherical shells as they provide longer service life than shells of homogeneous material under identical conditions
Effect of mechanical force along the interface of semi-infinite semiconducting medium and thermoelastic micropolar cubic crystal
No full textCrop-ecology and nutritional variability influence growth and secondary metabolites of Stevia rebaudiana Bertoni
No full textExploitation of combining ability and heterotic potential of okra under the sub-mountain region of Himalayan
No full textAbstract Okra (Abelmoschus esculentus L. Moench) is a vital vegetable crop well-known for its nutritional and economic importance, especially in tropical and subtropical regions. Studying heterosis and combining ability in okra is crucial for improving its yield, quality, and resistance to diseases and pests. Heterosis can produce offspring with superior traits, while understanding combining ability helps identify the best parental combinations for breeding programs. Since okra is often cross-pollinated, utilizing heterosis offers significant advantages. The research was conducted from 2022 to 2024 at the Experimental Farm, Department of Vegetable Science, College of Horticulture, Dr. YS Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh, India. The goal was to assess heterosis, combining ability, and gene action in okra to develop resistant cultivars with higher yields. The experimental material included an F1 population of 40 crosses derived from 10 parental lines crossed with four testers in a Line × Tester design during first week of May, 2022. These were evaluated over two years, the first week of June 2023 and 2024, along with a standard check variety, Punjab-8. Pooled data from both years were analyzed for 14 horticultural traits. The cross combinations showed higher heterotic estimates compared to heterobeltosis and standard heterosis for traits such as fruit weight and fruit yield per plant. Significant GCA effects for pod yield per plant were observed in parental lines including Kashi Pragati (40. 40.03), Kashi Satdhari (24. 37), Punjab Suhabani (14. 76), and COHF N- 9 (7. 49). Among the cross combinations for fruit yield per plant, Kashi Satdhari × Punjab Suhabani (66. 96), Kashi Pragati × Palam Komal (55. 69), COHF N- 2 × Kashi Chaman (29. 15), UHF- Okra- 4 × Varsha Uphar (25. 36), COHF N- 11 × Varsha Uphar(25. 25.35), COHF N- 1 × Palam Komal (21. 42), COHF N- 1 × Kashi Chaman (21. 22), and UHF- Okra- 2 × Punjab Suhabani (18. 18.70) showed superior and significant SCA effects. Identifying these parent lines and their hybrid combinations based on their combining ability can be important for developing high-yielding okra hybrids. Future research involving multi-location trials could further evaluate these parental lines and hybrids to replace current okra cultivars (both hybrids and varieties). Improving okra cultivars with higher yields and better quality could increase farmers’ profits, enhance food security and meet consumer demands
El uso de técnicas de inteligencia artificial en los sistemas de datos de enfermería: Scoping Review
No full textIntroduction. Artificial intelligence and machine learning are technologies that assist in uncovering patterns in data that can inform clinical decision-making. The Registered Nurses’ Association of Ontario has used artificial intelligence techniques to assist in understanding impactful clinical practices and implementation strategies. This scoping review aimed to discover the adaptation and implementation of various artificial intelligence and machine learning techniques in various healthcare settings using different data systems that house nursing-related data. Methodology. In March 2022, a scoping review was conducted to search for peer-reviewed literature using the following terms: “nursing”, “artificial intelligence”, “data systems”, “statistics”, and “aggregated data”. Studies were excluded if they were not relevant to nursing, utilized qualitative or mixed-methods analyses, were literature review articles, and did not focus on artificial intelligence or the use of patient-level data. Results. A total of 2,627 articles were retrieved, with 1,518 articles remaining after de-duplication. Through title and abstract screening, 1,347 articles remained. Following the full-text screening, 13 studies remained. Artificial intelligence techniques used by healthcare data systems include regression, neural networks, classification, and graph-based methods, among others. Discussion. There is a gap in the application of artificial intelligence methods in data systems that evaluate the impact of implementing best practices in nursing. More data systems are needed that employ artificial intelligence techniques to support the evaluation of best practices in nursing and other health professions. Conclusions. Various artificial intelligence techniques in data systems housing nursing-related data were retrieved. However, more data systems and research are needed in this area.Introducción. La inteligencia artificial y el aprendizaje automático son tecnologías que ayudan a descubrir patrones en los datos que pueden informar la toma de decisiones clínicas. La Asociación de Enfermeras Registradas de Ontario ha utilizado técnicas de inteligencia artificial para ayudar a comprender las prácticas clínicas que generan impacto y las estrategias de implementación. El objetivo de esta revisión es descubrir la adaptación e implementación de diversas técnicas de inteligencia artificial y aprendizaje automático en varios entornos sanitarios, utilizando diferentes sistemas de datos que almacenan datos relacionados con la enfermería. Metodología. En marzo de 2022, se realizó una revisión de alcance para buscar literatura revisada por pares utilizando los siguientes términos: «enfermería», «inteligencia artificial», «sistemas de datos», «estadística» y «datos agregados». Se excluyeron los estudios si no eran relevantes para la enfermería, utilizaban análisis cualitativos o de métodos mixtos, si eran artículos de revisión bibliográfica y no se centraban en la inteligencia artificial o en el uso de datos a nivel de paciente. Resultados. Se recuperó un total de 2,627 artículos, de los cuales 1,518 quedaron tras la eliminación de duplicados. Tras la revisión de títulos y resúmenes, quedaron 1,347 artículos. Posteriormente, con la revisión del texto completo, quedaron 13 estudios. Las técnicas de inteligencia artificial utilizadas por los sistemas de datos sanitarios incluyen, entre otras, la regresión, las redes neuronales, la clasificación y los métodos basados en gráficos. Discusión. Existe un vacío en la aplicación de métodos de inteligencia artificial en los sistemas de datos que evalúan el impacto de la implementación de buenas prácticas en enfermería. Se necesitan más sistemas de datos que empleen técnicas de inteligencia artificial para apoyar la evaluación de buenas prácticas en enfermería y otras profesiones de la salud. Conclusiones. Se recuperaron diversas técnicas de inteligencia artificial en sistemas de datos que almacenan datos relacionados con la enfermería. Sin embargo, se necesitan más sistemas de datos e investigación en este ámbito
Эпидемиология медицинских ошибок и инцидентов в неотложной медицине
No full textRelevance the issues of patient care and quality management have acquired particular relevance in modern healthcare. Improvement in the clinical performance of medical technologies has led to a significant reduction in deaths and complications associated with the disease and side effects of interventions. As a result, the share of additional harm related to the process of providing medical services has become more noticeable. Accurate data regarding the type, frequency and severity of active threats and incidents they cause are needed to reduce the likelihood and severity of additional harm. In this respect, emergency medical care is the subject of special attention and is characterized by the greatest difficulty in terms of obtaining valid and relevant information about deviations associated with health worker performance, equipment operation and patient behavior.The aim of the study was to explore the main epidemiological characteristics of medical errors and incidents associated with the provision of emergency medical care.Material and methods We present a literature review followed by an analytical study of the epidemiology of incidents and active threats (including medical errors) that precede those incidents in various areas of emergency medical care. By an incident, the authors understood an event with a patient that was more related to the process of providing medical care than to the course of the disease or comorbid conditions which led or could lead to causing additional harm. Active threats included events that subsequently became the direct cause of the incident (medical errors and malpractice, mistakes and deviations in patient behavior, emergency situations in the physical environment). By the “mortality from adverse events”, the authors understood the proportion of deaths from adverse events among all hospitalized patients. By the concept of “lethality associated with adverse events”, the authors denoted the proportion of deaths from adverse events among all the patients affected by adverse events. The search for information was carried out for the period of 1995–2021 using the following medical databases: medline; cochrane collaboration; embase; scopus; isi web of science. For analysis, we used prospective and retrospective observational studies of high methodological quality, meta-analyses and systematic reviews. For the statistical evaluation of frequency characteristics, indicators of incidence, prevalence, and incidence density were used. The calculation of generalized frequency indicators for large samples was carried out with a 95% confidence interval.Results The epidemiology of medical errors and incidents depends on the area in which emergency care is provided. For prehospital emergency medical care, there are 12.45 medical errors and 4.50 incidents with consequences for every 100 visits. In emergency departments, one in fourteen patients suffers additional harm which in 10.14% of cases has severe consequences, and in 3.18% of cases leads to unexpected death. In intensive care units, incidents related to the provision of medical care are recorded in every third patient in the amount of 1.55 per 1 patient. Of these, 58.67% of incidents are accompanied by harm, but the fatality associated with the incidents is only 0.77%. The prevalence of patients affected by incidents during the provision of anesthesia for children is almost 2 times higher than for adults (4.79% vs. 2.03%). At the same time, mortality due to anesthesia-related incidents in children is 11 times lower than in adults (0.27% versus 3.09%). The author draws attention to a number of factors contributing to the development of incidents during the provision of emergency medical care. These include environmental complexity, suboptimal configuration of the workspace, technological interface complexity, the effects of acute stress on performers, and organizational vulnerabilities. A special role was assigned to environmental complexity which was studied in detail both in terms of the complexity of the tasks being solved, and in connection with obstacles to solving problems. It was shown that the intensity of the influence of various components of environmental complexity is not the same in different departments providing emergency care. Particular attention was paid to the fact that organizational vulnerabilities reduce the effectiveness of protective mechanisms during the interaction of the human factor with a complex environment.Conclusion The study showed that the provision of emergency medical care is associated with moderately high risks of incidents, including severe and critical consequences for patients. The main factor contributing to the development of incidents is environmental complexity which becomes much harder to counter under the influence of organizational vulnerabilities. Identification and registration of errors and incidents in units providing medical care is difficult due to the short time of contact with patients, the high speed of situation update, and the constant impact of chronic and acute stressors on staff. In this connection, the optimization and improvement of the efficiency of the system for recording errors and incidents in departments providing emergency medical care remains an area for improvement.АКТУАЛЬНОСТЬ Вопросы управления качеством и безопасностью медицинской помощи приобрели особую актуальность в современном здравоохранении. Повышение клинической результативности используемых медицинских технологий привело к существенному сокращению числа смертей и осложнений, связанных с заболеванием и побочными эффектами вмешательств. В результате стала более заметной доля дополнительного вреда, связанного с самим процессом оказания медицинской помощи. Для уменьшения вероятности и тяжести дополнительного вреда необходимы точные данные, касающиеся вида, частоты и тяжести активных угроз и обусловленных ими инцидентов. Неотложная медицинская помощь (НМП) в этом отношении является предметом особого внимания и характеризуется наибольшей сложностью с точки зрения получения валидной и релевантной информации об отклонениях, связанных с действиями медицинских работников, работой оборудования и поведением больного.ЦЕЛЬ ИССЛЕДОВАНИЯ Изучить основные эпидемиологические характеристики медицинских ошибок и инцидентов, связанных с оказанием НМП.МАТЕРИАЛ И МЕТОДЫ Работа представляет собой обзор литературы с последующим аналитическим исследованием эпидемиологии инцидентов и предшествующих инцидентам активных угроз (в том числе медицинских ошибок) в различных сферах оказания НМП. Под термином «инцидент» авторы понимают происшествие с пациентом, в наибольшей степени связанное с процессом оказания медицинской помощи, чем с течением заболевания или сопутствующими состояниями, которое привело или могло привести к причинению дополнительного вреда. К активным угрозам были отнесены события, которые в последующем явились непосредственной причиной инцидента (медицинские ошибки и нарушения, ошибки и нарушения в поведении больного, аварийные ситуации в физической среде). Под «смертностью» от неблагоприятных событий авторы понимали долю умерших от неблагоприятных событий среди всех госпитализированных больных. Понятием «летальность», связанная с неблагоприятными событиями, авторы обозначали долю умерших от неблагоприятных событий среди всех больных с неблагоприятными событиями. Поиск информации проведен за период 1995–2021 гг. с использованием медицинских баз данных MEDLINE, Cochrane Collaboration, EMBASE, SCOPUS, ISI Web of Science. Для анализа использованы проспективные и ретроспективные обсервационные исследования высокого методологического качества, метаанализы и систематические обзоры. Для статистической оценки частотных характеристик применялись показатели инциденса, преваленса и плотности инцидентности. Расчет обобщенных частотных показателей для больших выборок был проведен с указанием 95% доверительного интервала.РЕЗУЛЬТАТЫ Эпидемиология медицинских ошибок и инцидентов зависит от области, в которой оказывается неотложная помощь. Для догоспитальной скорой медицинской помощи на каждые 100 выездов наблюдается 12,45 медицинских ошибки и 4,50 инцидентов с последствиями. В отделениях неотложной помощи один из 14 больных становится жертвой дополнительного вреда, который в 10,14% имеет тяжелые последствия, а в 3,18% случаев приводит к непредвиденной смерти. В отделениях интенсивной терапии и реанимации инциденты, связанные с оказанием медицинской помощи, регистрируются у каждого 3-го пациента в количестве 1,55 на одного больного. Из них 58,67% инцидентов сопровождается причинением вреда, но при этом суммарная летальность, связанная с инцидентами, составляет всего 0,77%. Преваленс больных с инцидентами при оказании анестезиологического пособия у детей почти в 2 раза выше, чем у взрослых (4,79% против 2,03%). В то же время летальность, обусловленная анестезиологическими инцидентами у детей, в 11 раз ниже, чем у взрослых (0,27% против 3,09%).Автором обращено внимание на ряд факторов, способствующих развитию инцидентов при оказании НМП. К ним отнесены сложность среды, неоптимальная конфигурация рабочего пространства, сложность технологического интерфейса, последствия воздействия острого стресса на исполнителей и организационные уязвимости. Особая роль при этом отведена сложности среды, которая подробно изучена как с точки зрения сложности решаемых задач, так и с точки зрения препятствий решению задач. Показано, что интенсивность влияния различных компонентов сложности среды неодинакова в различных подразделениях, оказывающих неотложную помощь. Обращено особое внимание на то, что организационные уязвимости снижают эффективность протективных механизмов в ходе взаимодействия человеческого фактора со сложной средой.ЗАКЛЮЧЕНИЕ Проведенное исследование показало, что оказание неотложной медицинской помощи сопряжено с умеренно высокими рисками развития инцидентов, в том числе с тяжелыми и критическими последствиями для пациентов. Главным фактором, способствующим развитию инцидентов, является сложность среды, противостояние которой значительно снижается при воздействии организационных уязвимостей. Идентификация и регистрация ошибок и инцидентов в подразделениях, оказывающих медицинскую помощь, затруднена в связи коротким временем контакта с больными, высокой скоростью обновления ситуации, постоянным воздействием хронических и острых стрессоров на персонал. В связи с этим оптимизация и повышение эффективности системы учета ошибок и инцидентов в отделениях, оказывающих неотложную медицинскую помощь, остается зоной улучшения
