Improvement of reliability of the guide couple of rapid forging press

Стаття присвячена опису та дослідженню конструкції направляючої пари швидкохідного штампувального преса холодного штампування та обгрунтуванню доцільності її застосування. Конструкцією передбачено виконання мастильних канавок направляючої опори у вигляді тороїдальної поверхні і сполученої з нею профільованої поверхні. Розглянута конструкція направляючої пари швидкохідного штампувального преса забезпечує підвищену надійність в процесі експлуатації. З цією метою розроблена математична модель, що дозволяє розраховувати значення основних характеристик направляючої опори. На базі розробленої математичної моделі виконано ряд розрахунків для різних варіантів профілювання мастильної канавки направляючої пари. Проведені розрахунки показали підвищення демпфирующей здатності опори, в порівнянні з традиційною конструкцією.The article describes the design of high-speed rail pair forge cold stamping and rationale of its application. Design provides for implementation of the oil grooves guide support in the form of the toroidal surface and mating with her profiled surface. Considered design of high-speed rail pair forge provides increased reliability during operation. For this purpose, a mathematical model allows to calculate the values of the basic characteristics of the bracket guide. On the basis of the developed mathematical model is made a series of calculations for different variants of the oil groove profiling guide couples. Calculations have shown increasing support damping capacity under dynamic loads, compared with traditional designs.Статья посвящена описанию и исследованию конструкции направляющей пары штампа для быстроходного штамповочного пресса холодной штамповки и обоснованию целесообразности ее применения. Конструкцией предусмотрено выполнение смазочных канавок направляющей колонны в виде тороидальной поверхности и сопряженной с ней профилированной поверхности. Рассматриваемая конструкция направляющей пары штампа для быстроходного штамповочного пресса обеспечивает повышенную надежность в процессе эксплуатации. С этой целью разработана математическая модель, позволяющая рассчитывать значения основных характеристик направляющей пары. На базе разработанной математической модели выполнен ряд расчетов для разных вариантов профилирования смазочной канавки направляющей пары. Проведенные расчеты показали повышение демпфирующей способности опоры при динамических нагрузках, по сравнению с традиционной конструкцией

Calculation of characteristics of hydrodynamical bearing with defined profile of sleeves based on Mathcad

Стаття присвячена проблемам моделювання роботи гідродинамічних опор ковзання в умовах рідинного тертя. Метою роботи є створення автоматизованої системи розрахунку характеристик опор ковзання з втулками довільного (гладкого) профілю. З цією метою розроблені методика і алгоритм вирішення задачі визначення несучої здатності опори ковзання з заданим профілем втулки, а також розроблені рекомендації з отримання раціональних профілів втулок підшипників ковзання. На базі даної методики розроблено систему розрахунку характеристик підшипника ковзання з застосуванням пакета комп'ютерної алгебри Mathcad. Розроблена розрахункова система була використана для пошуку варіантів раціонального профілювання втулки опори ковзання. Були знайдені варіанти профілю втулок опор ковзання, що забезпечують збільшення несучої здатності в порівнянні з опорами, в яких застосовується традиційний (круглий) профіль втулки. Також розроблена система дозволяє проводити експрес-порівняння характеристик опор ковзання з різними профілями втулки.The article is devoted to problems of hydrodynamic simulations of sliding friction in the liquid. The aim is to create an automated system for calculating the characteristics of sliding sleeves with arbitrary (smooth) profile. For this purpose developed a technique and algorithm for determining the carrying capacity of the bearing with arbitrary profile of the sliding sleeve, and developed recommendations for obtaining rational profiles of sleeve of bearing. On the basis of this methodology developed a system for calculating the characteristics of sliding bearing with the use of package of computer algebra Mathcad. Developed calculation system was used to search for variants of rational profiling of sleeve of sliding bearings. Were found variants of profile of sliding sleeves that provide an increase in carrying capacity compared with the supports that use traditional (round) profile of the sleeve. Designed system also allows quick comparison of the characteristics of sliding sleeves with different profiles.Статья посвящена проблемам моделирования работы гидродинамических опор скольжения в условиях жидкостного трения. Целью работы является создание автоматизированной системы расчета характеристик опор скольжения с втулками произвольного (гладкого) профиля. С этой целью разработаны методика и алгоритм решения задачи определения несущей способности опоры скольжения с задаваемым профилем втулки, а также разработаны рекомендации по получению рациональных профилей втулок подшипников скольжения. На базе данной методики разработана система расчета характеристик подшипника скольжения с применением пакета компьютерной алгебры Mathcad. Разработанная расчетная система была использована для поиска вариантов рационального профилирования втулки опоры скольжения. Были найдены варианты профиля втулок опор скольжения, обеспечивающие увеличение несущей способности по сравнению с опорами, в которых применяется традиционный (круглый) профиль втулки. Также разработанная система позволяет проводить экспресс-сравнение характеристик опор скольжения с различными профилями втулки

Gastrointestinal stromal tumors in elderly patients

To study the age-related characteristics of GISTs development in patients of older age group

Optimizing transcranial magnetic stimulation for spaceflight applications

As space agencies aim to reach and build installations on Mars, the crews will face longer exposure to extreme environments that may compromise their health and performance. Transcranial magnetic stimulation (TMS) is a painless non-invasive brain stimulation technique that could support space exploration in multiple ways. However, changes in brain morphology previously observed after long-term space missions may impact the efficacy of this intervention. We investigated how to optimize TMS for spaceflight-associated brain changes. Magnetic resonance imaging T1-weighted scans were collected from 15 Roscosmos cosmonauts and 14 non-flyer participants before, after 6 months on the International Space Station, and at a 7-month follow-up. Using biophysical modeling, we show that TMS generates different modeled responses in specific brain regions after spaceflight in cosmonauts compared to the control group. Differences are related to spaceflight-induced structural brain changes, such as those impacting cerebrospinal fluid volume and distribution. We suggest solutions to individualize TMS to enhance its efficacy and precision for potential applications in long-duration space missions. © 2023, The Author(s)

Functional Sensory-Motor Performance Following Long Term Space Flight: The First Results of "Field Test" Experiment

The effect that extended-duration space flights may have on human space travelers, including exploration missions, is widely discussed at the present time. Specifically, there is an increasing amount of evidence showing that the physical capacity of cosmonauts is significantly reduced after long-duration space flights. It is evident that the most impaired functions are those that rely on gravity, particularly up right posture and gait. Because of the sensorimotor disturbances manifested in the neurology of the posture and gait space flight and postflight changes may also be observed in debilitating motion sickness. While the severity of particular symptoms varies, disturbances in spatial orientation and alterations in the accuracy of voluntary movements are persistently observed after long-duration space flights. At this time most of the currently available data are primarily descriptive and not yet suitable for predicting operational impacts of most sensorimotor decrements observed upon landing on planetary surfaces or asteroids. In particular there are no existing data on the recovery dynamics or functionality of neurological, cardiovascular or muscle performance making it difficult to model or simulate the cosmonauts' activity after landing and develop the appropriate countermeasure that will ensure the rapid and safe recovery of crewmembers immediately after landing in what could be hostile environments. However and as a starting position, the videos we have acquired during recent data collection following the long duration flights of cosmonauts and astronauts walking and performing other tasks shortly after return from space flight speak volumes about their level of deconditioning. A joint Russian-American team has developed a new study specifically to address the changes in crewmembers performance and the recovery of performance with the intent of filling the missing data gaps. The first (pilot) phase of this study includes recording body kinematics and quantifying the coordination and timing of relatively simple basic movements - transition from seated and prone positions to standing, walking, stepping over obstacles, tandem walking, muscle compliance, as well as characteristics of postural sway and orthostatic tolerance. Testing for changes in these parameters have been initiated in the medical tent at the landing site. The first set of experiments showed that during the first hour after landing, cosmonauts and astronauts were able to execute (although slower and with more effort than preflight) simple movements such as egress from a seated or prone position and also to remain standing for 3.5 minutes without exhibiting pronounced cardiovascular changes. More challenging tests, however, demonstrated a prominent reduction in coordination - the obstacle task, for example, was performed at much slower speed and with a marked overestimation of the obstacle height and tandem walking was greatly degraded suggesting significant changes in proprioception, brainstem and vestibular function. There is some speculation that the neural changes, either from the bottom-up or top down may be long lasting; requiring compensatory responses that will modify or mask the adverse responses we have observed. Furthermore, these compensatory responses may actually be beneficial, helping achieve a more rapid adaptation to both weightlessness and a return to earth

Macro- And microstructural changes in cosmonauts' brains after long-duration spaceflight

Long-duration spaceflight causes widespread physiological changes, although its effect on brain structure remains poorly understood. In this work, we acquired diffusion magnetic resonance imaging to investigate alterations of white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF) compositions in each voxel, before, shortly after, and 7 months after long-duration spaceflight. We found increased WM in the cerebellum after spaceflight, providing the first clear evidence of sensorimotor neuroplasticity. At the region of interest level, this increase persisted 7 months after return to Earth. We also observe a widespread redistribution of CSF, with concomitant changes in the voxel fractions of adjacent GM. We show that these GM changes are the result of morphological changes rather than net tissue loss, which remained unclear from previous studies. Our study provides evidence of spaceflight-induced neuroplasticity to adapt motor strategies in space and evidence of fluid shift- induced mechanical changes in the brain. © 2020The Authors, some rights reserved.Peer reviewe

Recovery of Functional Sensorimotor Performance Following Long Duration Space Flight (Field Test)

No abstract availabl

Pilot Field Test: Performance of a Sit-to-Stand Test After Long-Duration Space Flight

BACKGROUND: Astronauts returning from the International Space Station are met by a team of recovery personnel typically providing physical assistance and medical support immediately upon landing. That is because long-duration spaceflight impacts astronauts' functional abilities. Future expeditions to planets or asteroids beyond the low Earth orbit, however, may require crewmembers to egress the vehicle and perform other types of physical tasks unassisted. It is therefore important to characterize the extent and longevity of functional deficits experienced by astronauts in order to design safe exploration class missions. Pilot Field Test (PFT) experiment conducted with participation of ISS crewmembers traveling on Soyuz expeditions 34S - 41S comprised several tasks designed to study the recovery of sensorimotor abilities of astronauts during the first 24 hours after landing and beyond. METHODS: The first test in the PFT battery sequence, and also the least demanding one from the sensorimotor perspective, was a Sit-to-Stand test. Test subjects were seated in the chair and had to stand up on command and remain standing for ten seconds. The subjects were instructed to stand up unassisted as quickly as they were able to, while maintaining postural control. Synchronized wireless inertial sensors mounted on the head, chest, lower back, wrists, and ankles were used to continuously log body kinematics. Crewmembers' blood pressure and heart rate were monitored and recorded with the Portapres and Polar systems. Each session was recorded with a digital video camera. During data collections occurring within the 24-hour postflight period, crewmembers were also asked to (1) evaluate their perceived motion sickness symptoms on a 20-point scale before and after completion of the test and (2) estimate how heavy they felt compared to their normal (preflight) body weight. Consent to participate in PFT was obtained from 18 crewmembers (11 US Orbital Segment [USOS] astronauts and 7 Russian cosmonauts). For 10 subjects, the first set of data was collected in the medical tent in Soyuz landing zone (1-2 hours after landing); the other 8 subjects were tested at the Kazakhstan deployment airport (4-5 hours after landing). 8 of the 11 astronauts were tested twice more within the first 24 hours postflight, at a refueling stop on the way to Houston (approximately 13 hours after landing) and at the Johnson Space Center (approximately 24 hours after landing). Later postflight data were collected in the first two weeks on some crewmembers. Finally, 6 astronauts were tested 60+ days after landing to establish a delayed baseline. RESULTS/DISCUSSION: Two of the 18 PFT participants felt too ill to attempt any tests in Kazakhstan (at either the landing zone or deployment airport). The remaining test subjects completed the Sit-to-Stand test and their reported motion sickness scores were unaffected by this task. The task completion times and body kinematics data analysis are currently underway. Preliminary analysis of astronaut data shows a steep improvement in the time to complete the task on the second data take, and in some cases, the trend continues through day six postflight. Head and trunk pitch angles and pitch rates were also examined and increases in all measures are evident throughout the observed recovery period (60+ days postflight). Interesting patterns of head and trunk pitch coordination have also emerged. One of the data analysis objectives is comparison of initial postflight performance and recovery of experienced crewmembers and first-time fliers. Another one - possible differences in performance between USOS and Russian crewmembers

Pilot Field Test: Recovery from a Simulated Fall and Quiet Stance Stability After Long-Duration Space Flight

Astronauts returning from the International Space Station (ISS) are met by a team of recovery personnel typically providing physical assistance and medical support immediately upon landing. That is because long-duration spaceflight impacts astronauts' functional abilities. Future expeditions to planets or asteroids beyond the low Earth orbit, however, may require crewmembers to egress the vehicle and perform other types of physical tasks unassisted. It is therefore important to characterize the extent and longevity of functional deficits experienced by astronauts in order to design safe exploration class missions. Pilot Field Test (PFT) experiment conducted with participation of ISS crewmembers traveling on Soyuz expeditions 34S - 41S comprised several tasks designed to study the recovery of sensorimotor abilities of astronauts during the first 24 hours after landing and beyond

Erratum to: Cortical reorganization in an astronaut’s brain after long-duration spaceflight (Brain Struct Funct, DOI 10.1007/s00429-015-1054-3)

peer reviewe