scholarly journals Kinematics of steam film wetting while quenching cylindrical samples in thermal oils

2021 ◽  
Vol 1208 (1) ◽  
pp. 012010
Author(s):  
Šefik Behrem ◽  
Bahrudin Hrnjica

Abstract The paper presents the determination of the velocity of the vapor front along the outer wall of a cylindrical specimen in the process of two-dimensional axisymmetric quenching of the samples in thermal oils. One thermal oil is Isorapid 277 HM heated to 40°C and the other thermal oil is Marquench 722 heated to 90°C. The experimental setup of the work consists of heating to a temperature of 850°C, then quenching three dimensionally different cylindrical probes. The dimensions of the probe were: ϕ25x100 ϕ50x150 and ϕ75x225 mm. All quenchings were done in strictly controlled conditions of the flow rate of the quenchant around the cylinder as well as maintaining the temperature of the quenchant within the maximum 40±2.5°C or 90d3°C, during the quenching of the samples. The velocity of movement of the steam front on the outer surface of the cylinder was determined from the time-measured values of temperatures at the marked points of each sample. The analysis of the steam front movement velocity along the cylinder wall starts from the moment the lower base of the probe touches the quenchant. During the process of immersing the test probe in the quenchant, in addition to measuring the temperatures in time, the time of lowering the probe to contact with the quenchant sample was also measured. The approximate average velocity of the vapor front was determined based on the indications of the lower and middle thermocouples located 1.5 mm below the outer surface of the cylinder wall. Based on the distance of one half the height of each probe and time, the velocity of the steam film movement or the kinematics of the steam film wetting was obtained. The obtained results were compared with the results of quenching in water and aqueous solutions of the same probes under the same strictly controlled conditions.

Author(s):  
Дмитрий Валериевич Судаков ◽  
Олег Валериевич Судаков ◽  
Людмила Валентиновна Кретинина ◽  
Наталья Владимировна Якушева ◽  
Артём Николаевич Шевцов

Статья посвящена построению прогноза эффективности реконструктивных вмешательств на магистральных нервах предплечья в зависимости от протяженности дефекта нервной ткани и особенностей последующего периода реабилитации пациентов. Данная тематика является весьма актуальной, так как с каждым годом во всем мире наблюдается определенный рост случаев травм различного генеза магистральных нервных стволов, которые затем нередко приводят к временной нетрудоспособности и даже инвалидности пациентов. Реконструктивная микрохирургия многие десятилетия пытается решить целый ряд проблем аутотрансплантации нервных стволов и повысить ее общую эффективность. Но из-за определенных проблем связанных с финансированием, некоторые вопросы трансплантологии и реабилитации остаются нерешенными и в настоящий момент. Все это придает представленной работе важное значение не только медицинского, но и социально - экономического плана. Целью работы стала попытка построения прогноза восстановительных операций на нервной ткани, с учетом объема пораженных структур и периода реабилитации. Объектами исследования стало 180 больных, которым по той или иной причине, осуществлялась реконструктивная операция на одном из магистральных нервов предплечья. Все пациенты были разделены на 3 группы по 60 человек, в зависимости от протяженности дефекта магистрального нерва: до 4 см, от 4 до 8 см и от 8 до 12 см. Последующее разделение внутри каждой группы на подгруппы производилось в зависимости от определенного поврежденного нерва (лучевой, локтевой, срединный). В работе изучалось течение раннего послеоперационного воспалительного процесса, с определением бактериальной микрофлоры в ране. Изучались и отдаленные последствия оперативного вмешательства. Своеобразной новизной для данной тематики в целом, стало выявление последующего установления инвалидности пациентов. Кроме того, важные данные были получены и по срокам реабилитации и частичного или полного восстановления утраченных функций по срокам в зависимости от размеров восстанавливаемого дефекта и от наличия или отсутствия необходимой реабилитации. Полученные в работе данные могут представлять интерес не только для врачей хирургов и травматологов, но и для организаторов здравоохранения, позволяя производить прогнозы по выздоровлению пациентов в каждой определенной клинической ситуации The article is devoted to the construction of a forecast of the effectiveness of reconstructive interventions on the main nerves of the forearm, depending on the length of the defect in the nervous tissue and the characteristics of the subsequent period of rehabilitation of patients. This topic is very relevant, since every year all over the world there is a certain increase in cases of injuries of various origins of the main nerve trunks, which then often lead to temporary disability and even disability of patients. For many decades, reconstructive microsurgery has been trying to solve a number of problems of autotransplantation of nerve trunks and improve its overall efficiency. But due to certain problems associated with funding, some issues of transplantation and rehabilitation remain unresolved at the moment. All this gives the presented work important not only medical, but also socio - economic importance. The aim of this work was to attempt to predict restorative operations on the nervous tissue, taking into account the volume of the affected structures and the period of rehabilitation. The objects of the study were 180 patients who, for one reason or another, underwent a reconstructive operation on one of the main nerves of the forearm. All patients were divided into 3 groups of 60 people, depending on the length of the main nerve defect: up to 4 cm, from 4 to 8 cm, and from 8 to 12 cm. Subsequent division within each group into subgroups was performed depending on the specific damaged nerve ( radial, ulnar, median). The work studied the course of the early postoperative inflammatory process, with the determination of bacterial microflora in the wound. The long-term consequences of surgery were also studied. A peculiar novelty for this topic as a whole was the identification of the subsequent establishment of disability in patients. In addition, important data were obtained on the timing of rehabilitation and partial or complete restoration of lost functions in terms of timing, depending on the size of the restored defect and on the presence or absence of the necessary rehabilitation. The data obtained in this work may be of interest not only for surgeons and traumatologists, but also for healthcare organizers, allowing them to make predictions about the recovery of patients in each specific clinical situation


2016 ◽  
Vol 20 (1) ◽  
pp. 13-22
Author(s):  
Beata Brzychczyk ◽  
Zbigniew Kowalczyk ◽  
Jan Giełżecki

AbstractThe objective of the paper was to analyse the use of the designed photobioreactor for freshwater microalgae cultivation in the controlled laboratory conditions. The work covered the design and construction of photobioreactors (PBR) and setting up comparative cultivations of freshwater microalgae chlorelli vulgaris along with determination of the biomass growth intensity for a varied amount of supplied culture medium. It was found out that the constructed PBR may be used for microalgae cultivation in the controlled conditions. The impact of the culture medium amount on the growth of chlorelli vulgaris was proved. As a result of the increase of culture medium concentration to 30.1-120.4 ml·l−1 of water, dry mass in photobioreactorsincreased respectively from 1.33 g·dm−3 to 4.68 g·dm−3.


Author(s):  
Carmen-Magdalena Camenidis ◽  
◽  
Irina Băițel ◽  
Amalia Oatu ◽  
Octavian Amzulescu ◽  
...  

The objective of this case study is to observe the existence of an anticipation mechanism at the muscle groups level of the upper limbs. We tried to highlighted this anticipation process by measuring the potential of surface electric for some muscle groups representing the kinematic chain on the right side, involved in the motor action of catching a basketball and a 3kg medicine ball with two hands to the chest. We conducted a case study of a 13-year-old child, female gender. As a measurement method, we used surface electromyography signals of the EMG Trigno Delsys wireless system with 16 electrodes. We determined the moment when the muscles come into action by increasing the potential of surface electric and the moment when the action of catching the ball takes place, using the information provided by the accelerometers incorporated in the sensors of the Delsys equipment used. Therefore, we obtained information about how different muscle groups come into action which helped us to get an idea of how the child's movement is structured. Based on results of accelerations and EMG signals acquired we have formulated conclusions regarding the neuromuscular control of the tested subject. We also planned for the future to test a larger group of participants in the study research of anticipation mechanism in children who do not practice any performance sports.


2007 ◽  
Vol 61 (1-2) ◽  
pp. 37-42 ◽  
Author(s):  
Gabriel Otava ◽  
Calin Mircu ◽  
Horia Cernescu ◽  
Violeta Igna

The timely detection of oestrus presents an important professional procedure with which cattle farmers, in addition to veterinarians, are very often faced, because failure to detect oestrus poses a big economic problem. The objective of this work is to evaluate the efficacy of discovering oestrus in cows by determining the progesterone concentration (P4) in blood plasma. This experiment covered 22 animals, including 15 cows and 7 heifers, in which spontaneous oestrus was discovered. P4 concentration was determined using the ELISA test in samples of blood taken from the animals at the moment of insemination. Of the 15 cows, four cows (26.6%) were not inseminated at the optimal time, and the P4 level in these animals was higher than 1 ng/ml. All the heifers showed a progesterone concentration of over 1 ng/ml, and a percentage of conception which was 85%. The high P4 level in heifers at the moment of insemination could also be a consequence of stress caused by the regrouping and separating of the animals. Even though the heifers were under stress, which is indicated by the high progesteronemia values at the moment of insemination, the percentage of conception among them was beyond expectations. Therefore, the determination of P4 values at the moment of insemination is a suitable method for improving reproduction management on cattle farms. Inappropriate treatment of cows which are expected to show oestrus can cause stress and an increase in the values of the blood concentration of P4. On the grounds of the results obtained in this work, no negative influence of stress on the insemination results in heifers was observed.


2005 ◽  
Vol 33 (4) ◽  
pp. 319-338
Author(s):  
Ron P. Podhorodeski ◽  
Paul Sobejko

Analysis of the forces involved in mechanical systems requires an understanding of the dynamic properties of the system's components. In this work, a project on the determination of both the location of the centre of mass and inertial properties is described. The project involves physical testing, the proposal of approximate models, and the comparison of results. The educational goal of the project is to give students and appreciation of second mass moments and the validity of assumptions that are often applied in component modelling. This work reviews relevant equations of motion and discusses techniques to determine or estimate the centre of mass and second moment of inertia. An example project problem and solutions are presented. The value of such project problems within a first course on the theory of mechanisms is discussed.


2009 ◽  
pp. 79-116
Author(s):  
Gianni Bianco ◽  
Pierluigi Cecati

- Water will be a basic problem in the future of the world. At the moment in Italy the main problem lies in water reserve reductions facing a growing demand, while for drinkable water more and more administrator authorities are facing a budget deficit. The causes of this national and local situation are the administrative monopoly and the absence of planning and coordination policies, that would rationalize water use without rationing it, starting from an awareness of the costs of different involved variables. The economic quality of spring and consumption water, the oldness of the waterworks and pipe networks, the extreme fragmentation of waterworks (often of minimal dimension), their territorial localisation, the absence of a common method of charges, the scanty use of analysis of management, are some of the causes of a unique and surprising variability of costs, proceeds and tariffs. This paper analyzes the generation and the structure of the costs of drinkable water in an area representative of many national characteristics on the environmental, physic and socio-economic level. The quest for more efficient forms of management and for a more transparent determination of the tariffs has been carried on through the use of custom indexes of productivity and of production. These indexes summarise the existence of scale economies, of pipe network related diseconomies, and of economies of localisation and density of the consumers. The paper presents a synthesis of the observations gathered from about two hundred waterworks subdivided by owner and entrepreneurial typologies


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