scholarly journals A STUDY OF THE IMPACT OF THE PNEUMATIC LOADING RATE ON DYNAMIC PARAMETERS FOR A LARGE-SIZED CYLINDRICAL SHELL

2020 ◽  
pp. 118-125
Author(s):  
Pestrenin V.M. ◽  
◽  
Pestrenina I.V. ◽  
Rusakov S.V. ◽  
Buzmakova G.V. ◽  
...  
Keyword(s):  
Cylindrical Shell ◽  
Solid Mechanics ◽  
Outer Space ◽  
Natural Oscillation ◽  
Elastic Cylindrical Shell ◽  
Time Interval ◽  
Rectangular Plates ◽  
Wide Range ◽  
Oscillation Frequencies ◽  
The Impact

The solid mechanics problem on the packaging and subsequent pneumatic deployment of large-sized shells is relevant due to the need to operate such structures in hard-to-reach places. In particular, such a place is outer space. The paper considers the elastic cylindrical shell deployment from a packed state by internal pressure in a finite time interval. The packaged shell consists of two rectangular plates joined by ideal (with no bending resistance) joint-hinges arranged at the edges. Both static and dynamic problems are considered. Solutions are obtained on the basis of a geometrically nonlinear model of an elastic body using the ANSYS engineering package. It is shown that the pneumatic loading of an elastic structure is accompanied by its oscillations with increasing frequency and the amplitude decreasing in time. The period of shell oscillations is found to be dependent on the operating loading pressure and independent of the pressure supply rate, and it almost equals the period of oscillations of the statically loaded shell under the same pressure. The wide range variation in the natural oscillation frequencies of the structure during pneumatic deployment, which is revealed in the study, is of great importance since it makes possible to predict resonant modes accompanying the process. The results of the study will be used in problems of mechanics related to the pneumatic deployment of shell structures (for example, telescope reflectors, antennas, etc.) in space.

Development and Research of Mathematical Models of Deployment of Mobole Parts of Transformable Space Construction. Part I

2020 ◽  
Vol 21 (1) ◽  
pp. 51-64
Author(s):  
S. A. Kabanov ◽  
B. A. Zimin ◽  
F. V. Mitin
Keyword(s):  
Mathematical Models ◽  
Three Dimensional ◽  
Transition Process ◽  
Natural Oscillation ◽  
Lagrange Equations ◽  
Brushless Dc ◽  
Wide Range ◽  
Space Construction ◽  
Dimensional Parameters ◽  
The Impact

The process of deployment elements of constructions and adjustment of the radio-reflecting network of large-sized transformable space-based reflector with the use of a cable-stayed form maintenance system is considered. The deployment process can be broken down into separate phases. At each stage, the movement is due to the impact on the design of the actuator — the element of the control system. Energy for the deployment of the reflector elements is produced by drives, in particular an electric machine. The use of this type of actuator allows you to control the process of disclosure. Due to the fact that currently achieved a huge process in computer technology that allows you to perform three-dimensional computing operations in a short time, it is particularly important to use optimal control algorithms. When deployment the reflector for two types of motion — rotational and translational — mathematical models based on Lagrange equations of the II-kind are obtained. These mathematical models take into account such parameters as dissipation, the presence of longitudinal and transverse deformation. The models provide for the presence of a stop and a lock, as an Executive element in the deployment selected brushless DC motor. All the observations made allow us to formulate a smooth statement disclose items on the stop with minimum oscillation of the structure. The developed models allow to analyze the n-th number of natural oscillation frequencies. Modeling with different parameters of the model is carried out. The parameters of the transition process of the spoke at the opening of the first link with the other links embedded in it and at the fully covered spoke are analyzed. It is shown that depending on the mass-dimensional parameters there is a significant change in the dynamics. For the spoke extension stage, the weight and size characteristics have little effect on the opening dynamics. The smaller the Young’s modulus and density of the material, the greater the damped longitudinal oscillations.. The simulation of this stage with a spoke made of different materials is carried out. Various methods are proposed to reduce the opening time at all stages and minimize transverse and longitudinal oscillations. The possibility of application of the developed mathematical models for a wide range of tasks is shown.

scholarly journals INVESTIGATIONS OF VIBRO-OSCILLATORY PROVESSES OF THE SUPPORTS OF OFFSHORE STATIONARY PLATFORMS UNDER CONDITIONS OF ALTERNATING VORTEX FORMATION CAUSED BY THE INFLUENCE OF SEA CURRENTS

Akustika ◽  
2019 ◽  
Vol 32 ◽  
pp. 262-266
Author(s):  
Ivan Starokon ◽  
Y.M. Ovsannikov ◽  
A.O. Golovachev
Keyword(s):  
Frequency Spectrum ◽  
Characteristic Frequency ◽  
Natural Frequencies ◽  
Vortex Formation ◽  
Natural Oscillation ◽  
Hydrodynamic Forces ◽  
Offshore Platforms ◽  
Wide Range ◽  
Sea Currents ◽  
Oscillation Frequencies

Offshore platforms are exposed to hydrodynamic forces of a non-stationary nature and a wide range of frequencies. At present, hydrodynamic forces arising under conditions of alternating vortex formation have been poorly studied. These vortices are caused by the sea currents flowing around the supports of the platform, and due to their periodic occurrence and disruption, they lead to oscillations of the supports of the offshore platforms. Of particular danger are the cases of resonance of the characteristic frequency spectrum of hydrodynamic forces from the "occurrence-stalling" of vortices and natural frequencies of elements of the platform supports, which can cause fatigue damages in the platform supports. The article developed a method for determining the natural oscillation frequencies of marine supports and described the conditions under which the occurrence of alternating vortex formation is possible.

scholarly journals Review: The Impact of Metal Additive Manufacturing on the Aerospace Industry

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1286 ◽  
Author(s):  
Shahir Mohd Yusuf ◽  
Samuel Cutler ◽  
Nong Gao
Keyword(s):  
Additive Manufacturing ◽  
Outer Space ◽  
Aerospace Industry ◽  
Space Vehicles ◽  
Metal Additive Manufacturing ◽  
Wide Range ◽  
Metallic Parts ◽  
The Impact ◽  
Research Stage ◽  
Metal Additive

Metal additive manufacturing (AM) has matured from its infancy in the research stage to the fabrication of a wide range of commercial functional applications. In particular, at present, metal AM is now popular in the aerospace industry to build and repair various components for commercial and military aircraft, as well as outer space vehicles. Firstly, this review describes the categories of AM technologies that are commonly used to fabricate metallic parts. Then, the evolution of metal AM used in the aerospace industry from just prototyping to the manufacturing of propulsion systems and structural components is also highlighted. In addition, current outstanding issues that prevent metal AM from entering mass production in the aerospace industry are discussed, including the development of standards and qualifications, sustainability, and supply chain development.

THE IMPACT OF LEADERSHIP PRACTICES TO TEAM MEMBERS’ SATISFACTION

2009 ◽  
Vol 8 (1) ◽  
Author(s):  
Chalimah .
Keyword(s):  
Conflict Resolution ◽  
Leadership Practices ◽  
Hotel Industry ◽  
Leader Behavior ◽  
Team Leader ◽  
Shop Floor ◽  
Team Members ◽  
Top Executives ◽  
Wide Range ◽  
The Impact

eamwork is becoming increasingly important to wide range of operations. It applies to all levels of the company. It is just as important for top executives as it is to middle management, supervisors and shop floor workers. Poor teamwork at any level or between levels can seriously damage organizational effectiveness. The focus of this paper was therefore to examine whether leadership practices consist of team leader behavior, conflict resolution style and openness in communication significantly influenced the team member’s satisfaction in hotel industry. Result indicates that team leader behavior and the conflict resolution style significantly influenced team member satisfaction. It was surprising that openness in communication did not affect significantly to the team members’ satisfaction.

Stress, anxiety, depression and burnout in frontline health care workers during COVID-19 pandemic: a brief systematic review and new data from Russia

2021 ◽  
Author(s):  
Ekaterina Mosolova ◽  
Dmitry Sosin ◽  
Sergey Mosolov
Keyword(s):  
Risk Factors ◽  
Systematic Review ◽  
Female Gender ◽  
Assessment Tools ◽  
Care Workers ◽  
Younger Age ◽  
Wide Range ◽  
Associated Risk Factors ◽  
Anxiety Depression ◽  
The Impact

During the COVID-19 pandemic, healthcare workers (HCWs) have been subject to increased workload while also exposed to many psychosocial stressors. In a systematic review we analyze the impact that the pandemic has had on HCWs mental state and associated risk factors. Most studies reported high levels of depression and anxiety among HCWs worldwide, however, due to a wide range of assessment tools, cut-off scores, and number of frontline participants in the studies, results were difficult to compare. Our study is based on two online surveys of 2195 HCWs from different regions of Russia during spring and autumn epidemic outbreaks revealed the rates of anxiety, stress, depression, emotional exhaustion and depersonalization and perceived stress as 32.3%, 31.1%, 45.5%, 74.2%, 37.7% ,67.8%, respectively. Moreover, 2.4% of HCWs reported suicidal thoughts. The most common risk factors include: female gender, nurse as an occupation, younger age, working for over 6 months, chronic diseases, smoking, high working demands, lack of personal protective equipment, low salary, lack of social support, isolation from families, the fear of relatives getting infected. These results demonstrate the need for urgent supportive programs for HCWs fighting COVID-19 that fall into higher risk factors groups.

A MODELING SYSTEM FOR CLIMATE CHANGE RISK ASSESSMENT, MANAGEMENT AND HEDGING IN COASTAL AREAS

2017 ◽  
Author(s):  
Sergei Soldatenko ◽  
Sergei Soldatenko ◽  
Genrikh Alekseev ◽  
Genrikh Alekseev ◽  
Alexander Danilov ◽  
...  
Keyword(s):  
Climate Change ◽  
Risk Assessment ◽  
Coastal Areas ◽  
Mitigation Strategies ◽  
System Structure ◽  
The Arctic ◽  
Risk Modeling ◽  
Wide Range ◽  
Adverse Weather ◽  
The Impact

Every aspect of human operations faces a wide range of risks, some of which can cause serious consequences. By the start of 21st century, mankind has recognized a new class of risks posed by climate change. It is obvious, that the global climate is changing, and will continue to change, in ways that affect the planning and day to day operations of businesses, government agencies and other organizations and institutions. The manifestations of climate change include but not limited to rising sea levels, increasing temperature, flooding, melting polar sea ice, adverse weather events (e.g. heatwaves, drought, and storms) and a rise in related problems (e.g. health and environmental). Assessing and managing climate risks represent one of the most challenging issues of today and for the future. The purpose of the risk modeling system discussed in this paper is to provide a framework and methodology to quantify risks caused by climate change, to facilitate estimates of the impact of climate change on various spheres of human activities and to compare eventual adaptation and risk mitigation strategies. The system integrates both physical climate system and economic models together with knowledge-based subsystem, which can help support proactive risk management. System structure and its main components are considered. Special attention is paid to climate risk assessment, management and hedging in the Arctic coastal areas.

The Management of Post-Tonsillectomy Morbidity in Patients With Sleep Apnoea

2019 ◽  
Vol 70 (10) ◽  
pp. 3738-3740
Keyword(s):  
Day Surgery ◽  
Sleep Apnoea ◽  
Integrative Approach ◽  
Multicenter Studies ◽  
Therapeutic Modalities ◽  
Advantages And Disadvantages ◽  
Obstructive Sleep ◽  
Wide Range ◽  
The Impact ◽  
Surgery Center

The Tonsillectomy in children or adults is an intervention commonly encountered in the ENT (Ear Nose and Throat) and Head and Neck surgeon practice. The current tendency is to perform this type of surgery in major ambulatory surgery centers. Two objectives are thus pursued: first of all, the increase of the patient quality of life through the reintegration into the family as quickly as possible and secondly, the expenses associated with continuous hospitalization are reduced. Any tertiary (multidisciplinary) sleep center must ensure the complete diagnosis and treatment (including surgery) of sleep respiratory disorders. Under these conditions the selection of patients and especially the implementation of the specific protocols in order to control the postoperative complications it becomes essential. The present paper describes our experience of tonsillectomy as treatment for selected patients with chronic rhonchopathy (snoring) and mild to moderate obstructive sleep apnoea. It was presented the impact of antibiotics protocols in reducing the main morbid outcomes following tonsillectomy, in our day surgery center. The obtained results can also be a prerequisite for the integrative approach of the patients with sleep apnoea who were recommended surgical treatment. Considering the wide range of therapeutic modalities used in sleep apnoea, each with its specific advantages and disadvantages, more extensive and multicenter studies are needed. Keywords: post-tonsillectomy morbidity, day surgery center, sleep disorders

Cognitive Impact of Cerebellar Damage: Is There a Future for Cognitive Rehabilitation?

2018 ◽  
Vol 17 (3) ◽  
pp. 199-206 ◽  
Author(s):  
Kim van Dun ◽  
Frank V. Overwalle ◽  
Mario Manto ◽  
Peter Marien
Keyword(s):  
Affective Disorders ◽  
Cognitive Rehabilitation ◽  
Therapeutic Interventions ◽  
Posterior Fossa Surgery ◽  
Daily Life Activities ◽  
Wide Range ◽  
Affective Deficits ◽  
Cerebellar Injury ◽  
Cognitive Therapies ◽  
The Impact

Background & Objective: During the past 3 decades, numerous neurophysiological, neuroimaging, experimental and clinical studies have evidenced a crucial role for the cerebellum in cognitive, affective and behavioral functions. As a result of the acknowledged modulatory role of the cerebellum upon remote structures such as the cerebral cortex, cerebellar injury may give rise to a constellation of behavioral, affective and cognitive symptoms (Schmahmann's Syndrome). In sharp contrast to the wide range of therapeutic interventions to treat cognitive and affective disorders following cerebral cortical lesions and despite the consequences of Schmahmann’s syndrome upon daily life activities, the literature is surprisingly only scantly documented with studies investigating the impact of cognitive therapies on cerebellar induced cognitive and affective disorders. This survey aims to present an overview of the therapeutic interventions available in the literature as a possible treatment for Schmahmann’s Syndrome after cerebellar injury, after posterior fossa surgery in children, and in children with neurodevelopmental disorders. Although systematical studies are clearly warranted, available evidence suggests that cerebellar-induced cognitive and affective disorders should be treated in a specific way. Approaches where the patients are explicitly made aware of their deficits and are considered to act as an “external cerebellum” are the most promising. Conclusion: The study of the anatomical connectivity of the cerebellar microcomplexes involved in cognitive/affective deficits is likely to play a major-role in the future.

Religion and Medicine

2020 ◽  
Author(s):  
Jeff Levin ◽  
Stephen G. Post
Keyword(s):  
Clinical Decision Making ◽  
Well Being ◽  
Clinical Decision ◽  
Religion And Medicine ◽  
Physical And Mental Health ◽  
Faith Based ◽  
Baylor University ◽  
Wide Range ◽  
History Of ◽  
The Impact

In Religion and Medicine, Dr. Jeff Levin, distinguished Baylor University epidemiologist, outlines the longstanding history of multifaceted interconnections between the institutions of religion and medicine. He traces the history of the encounter between these two institutions from antiquity through to the present day, highlighting a myriad of contemporary alliances between the faith-based and medical sectors. Religion and Medicine tells the story of: religious healers and religiously branded hospitals and healthcare institutions; pastoral professionals involved in medical missions, healthcare chaplaincy, and psychological counseling; congregational health promotion and disease prevention programs and global health initiatives; research studies on the impact of religious and spiritual beliefs and practices on physical and mental health, well-being, and healing; programs and centers for medical research and education within major universities and academic institutions; religiously informed bioethics and clinical decision-making; and faith-based health policy initiatives and advocacy for healthcare reform. Religion and Medicine is the first book to cover the full breadth of this subject. It documents religion-medicine alliances across religious traditions, throughout the world, and over the course of history. It summarizes a wide range of material of relevance to historians, medical professionals, pastors and theologians, bioethicists, scientists, public health educators, and policymakers. The product of decades of rigorous and focused research, Dr. Levin has produced the most comprehensive history of these developments and the finest introduction to this emerging field of scholarship.

Textual Transformations

2019 ◽  
Keyword(s):  
Early Modern ◽  
Financial Incentives ◽  
Book History ◽  
John Dryden ◽  
Book Production ◽  
Original Essays ◽  
Wide Range ◽  
Lucy Hutchinson ◽  
The Many ◽  
The Impact

This collection of twelve original essays by an international team of eminent scholars in the field of book history explores the many ways in which early modern books were subject to reworking, re-presentation, revision and reinterpretation. Their history is often the history of multiple, sometimes competing, agencies as their texts were re-packaged, redirected and transformed in ways that their original authors might hardly recognize. The essays discuss the processes of editing, revision, redaction, selection, abridgement, glossing, disputation, translation and posthumous publication that resulted in a textual elasticity and mobility that could dissolve distinctions between text and paratexts, textuality and intertextuality, manuscript and print, author and reader or editor, such that title and author’s name are no longer sufficient pointers to a book’s identity or contents. The essays are alive to the impact of commercial and technological aspects of book production and distribution (discussing, for example, the career of the pre-eminent bookseller John Nourse, the market appeal of abridgements, and the financial incentives to posthumous publication), but their interest is also in the many additional forms of agency that shaped texts and their meanings as books were repurposed to articulate, and respond to, a variety of cultural and individual needs. They engage with early modern religious, political, philosophical and scholarly trends and debates as they discuss a wide range of genres and kinds of publication (including fictional and non-fictional prose, verse miscellanies, abridgements, sermons, religious controversy) and of authors and booksellers (including Lucy Hutchinson, Richard Baxter, Thomas Burnet, Elizabeth Rowe, John Dryden, and Samuel Taylor Coleridge, Lucy Hutchinson, Henry Maundrell, John Nourse; Jonathan Swift, Samuel Richardson, John Tillotson, Isaac Watts and John Wesley).

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