scholarly journals Riddance jamming of pipeline shut-off valves

2021 ◽  
Vol 29 (3) ◽  
pp. 83-97
Author(s):  
Alexander A. Bazarov ◽  
Nataliya V. Bondareva ◽  
Ashot A. Navardyan
Keyword(s):  
Ambient Temperature ◽  
Thermal Deformation ◽  
Thermal Stresses ◽  
The Body ◽  
Deformation Model ◽  
Horizontal Line ◽  
Average Height ◽  
Temperature Decrease ◽  
Structural Elements ◽  
Valve Body

The paper conciders the problems of modeling the processes of thermal deformation of valves with an ambient temperature decrease. Some type of wedge valves are exposed to jamming. Heating the valve body is used to eliminate jamming. This problem is common for rigid wedge valves but the reasons not fully explained. Sometimes the valve stem is destroyed due to the significant power of the gate valve electric drives. The aim of the study is to determine the nature of the stress distribution between the structural elements of the valve, which are the cause of jamming with an ambient temperature decrease, and to search for the parameters of the heating process that ensure minimum energy consumption and time. To study the thermal processes in the valve body, a numerical model describing the heat transfer in the structural elements and the fluid is developed. The thermal model is combined with the elastic deformation model. That allows to make compatible calculations without introducing additional errors. The thermal deformations appear in the cooling process and give rise to disproportionate changes in valve dimensions and thermal stresses. Thermal stresses are the cause of jamming. Modeling of the processes of thermal deformation with a decrease in temperature showed that pressure forces of different signs arise in the middle plane of the wedge. At the average height of the horizontal line, there is a compacting pressure and at the lower and upper points there is a stretching pressure. To eliminate the compacting forces local heating was performed in several areas of the body. It was found that the most effective option is to heat the lower hemispherical surface of the body. Heating for thirty minutes reduces the thermal stresses in the wedge and compressive forces to minimum values. For this reason, jamming of the valve is eliminated. For heating the body, a hemispherical induction heater with a magnetic core is provided. The proposed design allows the use of industrial frequency voltage without a step-down transformer and reactive power compensation.

Effect of Thermal Deformation on Part Errors in Metal Powder Based Additive Manufacturing Processes

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Ratnadeep Paul ◽  
Sam Anand ◽  
Frank Gerner
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Thermal Deformation ◽  
Thermal Stresses ◽  
Geometric Model ◽  
Virtual Manufacturing ◽  
Deformation Model ◽  
Fe Model ◽  
Slice Thickness ◽  
Part Orientation

In metal additive manufacturing (AM) processes, parts are manufactured in layers by sintering or melting metal or metal alloy powder under the effect of a powerful laser or an electron beam. As the laser/electron beam scans the powder bed, it melts the powder in successive tracks which overlap each other. This overlap, called the hatch overlap, results in a continuous cycle of rapid melting and resolidification of the metal. The melting of the metal from powder to liquid and subsequent solidification causes anisotropic shrinkage in the layers. The thermal strains caused by the thermal gradients existing between the different layers and between the layers and the substrate leads to considerable thermal stresses in the part. As a result, stress gradients develop in the different directions of the part which lead to distortion and warpage in AM parts. The deformations due to shrinkage and thermal stresses have a significant effect on the dimensional inaccuracies of the final part. A three-dimensional thermomechanical finite element (FE) model has been developed in this paper which calculates the thermal deformation in AM parts based on slice thickness, part orientation, scanning speed, and material properties. The FE model has been validated and benchmarked with results already available in literature. The thermal deformation model is then superimposed with a geometric virtual manufacturing model of the AM process to calculate the form and runout errors in AM parts. Finally, the errors in the critical features of the AM parts calculated using the combined thermal deformation and geometric model are correlated with part orientation and slice thickness.

scholarly journals Insect body size changes under future warming projections: a case study of Chironomidae (Insecta: Diptera)

Hydrobiologia ◽  
2021 ◽  
Author(s):  
Rungtip Wonglersak ◽  
Phillip B. Fenberg ◽  
Peter G. Langdon ◽  
Stephen J. Brooks ◽  
Benjamin W. Price
Keyword(s):  
Body Size ◽  
Ambient Temperature ◽  
Wing Length ◽  
The Body ◽  
Mesocosm Experiments ◽  
Future Warming ◽  
Increasing Temperature ◽  
Emergence Date ◽  
Average Body

AbstractChironomids are a useful group for investigating body size responses to warming due to their high local abundance and sensitivity to environmental change. We collected specimens of six species of chironomids every 2 weeks over a 2-year period (2017–2018) from mesocosm experiments using five ponds at ambient temperature and five ponds at 4°C higher than ambient temperature. We investigated (1) wing length responses to temperature within species and between sexes using a regression analysis, (2) interspecific body size responses to test whether the body size of species influences sensitivity to warming, and (3) the correlation between emergence date and wing length. We found a significantly shorter wing length with increasing temperature in both sexes of Procladius crassinervis and Tanytarsus nemorosus, in males of Polypedilum sordens, but no significant relationship in the other three species studied. The average body size of a species affects the magnitude of the temperature-size responses in both sexes, with larger species shrinking disproportionately more with increasing temperature. There was a significant decline in wing length with emergence date across most species studied (excluding Polypedilum nubeculosum and P. sordens), indicating that individuals emerging later in the season tend to be smaller.

Seasonal changes in the body surface temperature of Hanwoo (Bos taurus coreanae) steers

2014 ◽  
Vol 54 (9) ◽  
pp. 1476 ◽  
Author(s):  
N. Y. Kim ◽  
S. J. Kim ◽  
J. H. Park ◽  
M. R. Oh ◽  
S. Y. Jang ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Ambient Temperature ◽  
Body Surface ◽  
Seasonal Changes ◽  
Bos Taurus ◽  
The Body ◽  
Body Regions ◽  
Extreme Cold ◽  
Body Surface Temperature ◽  
Average Body

The present study aimed to gather basic information on measuring body surface temperature (BST) of cattle by using infrared thermography (IRT) and find out whether BST measurement is a useful method to detect thermal balance of livestock. Twenty-seven Hanwoo steers were examined in a field trial. The BST of five body regions (eye, nose, horn, ear, rear) was measured five times daily, with three replicates, during 3 days each season. Body surface temperature of cattle is directly affected by ambient temperature and humidity, and showed different ranges for each region. The BSTs of nose, horns and ears were significantly (P < 0.05) lower than those of eyes and rear area. Rear-area BST was significantly lower than eye-area BST when the ambient temperature was low (P < 0.05). Eye BST (EBST) was highest (P < 0.05) and the least variable of all BSTs measured. Therefore, the eye area of cattle was the most thermostable part of the body. There were significant (P < 0.05) differences among seasonal EBSTs of steers. The EBST range was highest in the summer (37.9–42.2°C), followed by autumn (34.3–37.4°C), spring (33.8–36.5°C) and winter (29.8–32.6°C). During extreme cold, EBST showed a large standard deviation. During conditions of extreme heat, EBST was above the average body temperature of cattle. The results of the present study indicated that BST well reflects the thermal circumstances surrounding animals and may be used as one of the effective tools for precision cattle farming.

Effect of Changes in Ambient Temperature on Spontaneous Activity, Food Intake and Body Weight of Goldthioglucose-Obese and Nonobese Mice

1957 ◽  
Vol 188 (3) ◽  
pp. 435-438 ◽  
Author(s):  
M. J. Fregly ◽  
N. B. Marshall ◽  
J. Mayer
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Ambient Temperature ◽  
The Body ◽  
Lower Body ◽  
Obese Mice ◽  
Ambient Temperatures ◽  
Exposure To Cold ◽  
Running Activity ◽  
Body Weights

Goldthioglucose-obese mice cannot adjust their food intake to meet the increased energy requirements due to cold. At all ambient temperatures above 15°C the spontaneous running activity of these animals is less than that observed for nonobese controls. Activity of obese mice is maximal at 19°C and minimal at 15°C or lower. Body weights decrease during exposure to cold. In contrast to that of obese mice, running activity of nonobese controls is maximal at an ambient temperature of 25°C but nearly ceases at 15°C or lower. The food intake of these animals increases in the cold and remains elevated even at temperatures at which activity decreases. The body weight of nonobese controls is either maintained constant or increases during exposure to cold air.

Influence of the environmental temperature on the post-partum testosterone surge in the rat

1987 ◽  
Vol 115 (4) ◽  
pp. 478-482 ◽  
Author(s):  
J. Roffi ◽  
F. Chami ◽  
P. Corbier ◽  
D. A. Edwards
Keyword(s):  
Ambient Temperature ◽  
Environmental Temperature ◽  
Post Partum ◽  
Serum Testosterone ◽  
The Body ◽  
Male Rats ◽  
Effect Of Temperature ◽  
Male Rat ◽  
Foster Mother ◽  
The Central Nervous System

Abstract. In the neonatal male rat, a rapid and transient increase in serum testosterone occurs about 2 h after birth. This post-partum testosterone surge (PPTS) has been implicated in the masculinization and defeminization of the central nervous system. The present study shows that environmental temperature can have a profound influence on the PPTS. Male rats were delivered from their mothers by caesarean section on day 22 of gestation. Immediately thereafter, neonatal males were placed at an ambient temperature of either 18, 21, 24 or 30°C. With 2 h of exposure, the body temperature was in close correspondence with the ambient temperature. The PPTS was clearly abolished in the pups exposed for 2 h at either 18 or 21°C. The effect of temperature was reversible: by placing pups at either 18 or 21°C for 2 h after delivery, and then rewarming by placing them with a foster mother, the PPTS was delayed until 4 h after birth, i.e. 2 h after the beginning of rewarming. Thus, environmental cooling appears to retard the development of neural and/or endocrine systems mediating the PPTS. Aberrant maternal care which would produce substantial cooling of the male pups would be expected to affect the PPTS, which in turn might affect the sexuality of male progeny.

scholarly journals Two new species of the genus Crenicichla Heckel, 1840 from the upper rio Uruguay drainage (Perciformes: Cichlidae)

2007 ◽  
Vol 5 (4) ◽  
pp. 449-456 ◽  
Author(s):  
Carlos A. S. de Lucena
Keyword(s):  
New Species ◽  
Species Group ◽  
The Body ◽  
The Other ◽  
Horizontal Line ◽  
Lower Edge ◽  
Middle Portion ◽  
Lateral Band ◽  
Two New Species ◽  
Vertical Bars

Two new species of the genus Crenicichla from the upper rio Uruguay basin are described, Crenicichla hadrostigma and C. empheres. Both are included in the C. missioneira species group along with C. missioneira, C. minuano, C. tendybaguassu, C. igara, and C. jurubi, all occurring in the upper and middle rio Uruguay drainage. Crenicichla hadrostigma is distinguished by the conspicuous ocellated posttemporal blotch, absence of a humeral spot and lateral band, and the presence in males of nine to 16 narrow vertical bars extending from the dorsum to a horizontal line that passes through the lower edge of pectoral axilla. Crenicichla empheres is distinguished from the other species of the missioneira-group by the presence of six to eight horizontally elongate dark blotches along the middle portion of the body, slightly below the upper lateral line, absence of a lateral band, presence in males of numerous dark and irregularly arranged spots on nape, back, and sides of body, and isognathous mouth. A key to the species from rio Uruguay basin is presented.

scholarly journals New World screwworm (Cochliomyia hominivorax) myiasis in feral swine of Uruguay: One Health and transboundary disease implications

2020 ◽  
Author(s):  
Martín Altuna ◽  
Paul V. Hickner ◽  
Gustavo Castro ◽  
Santiago Mirazo ◽  
Adalberto A. Pérez de León ◽  
...  
Keyword(s):  
South America ◽  
Ambient Temperature ◽  
New World ◽  
One Health ◽  
Animal Health ◽  
Relative Size ◽  
The Body ◽  
Cochliomyia Hominivorax ◽  
Feral Swine ◽  
Endemic Areas

Abstract BackgroundFeral swine (Sus scrofa) are highly invasive and threaten animal and public health in the Americas. New World screwworm (Cochliomyia hominivorax) is listed by the World Organization for Animal Health as a notifiable infestation because myasis cases affect livestock, wildlife, and humans in endemic areas, and outbreaks can be of high socioeconomic consequence in regions where screwworm was eradicated. However, a knowledge gap exists on screwworm infestation of feral swine in South America where C. hominivorax is endemic. Here, we report infestation with C. hominivorax in feral swine harvested in the Department of Artigas where the Republic of Uruguay shares borders with Brazil and Argentina. MethodsMyiasis caused by the larvae of C. hominivorax were identified in feral swine with the support and collaboration of a local feral swine hunting club over a three-year period in the Artigas Department of Uruguay. Harvested feral swine were examined for the presence of lesions where maggots causing the myiasis could be sampled and processed for taxonomic identification. The sites of myiasis on the body of infested feral swine and geospatial data for each case were recorded. Feral swine sex and relative size were registered along with ambient temperature and precipitation.ResultsMyiases caused by screwworms were recorded in 27 of 618 feral swine harvested. Cases detected in males over 40 kg were associated with wounds that, because of their location, were likely caused by aggressive dominance behavior between adult males. The overall prevalence of screwworm infestation in feral swine was associated with ambient temperature, but not precipitation. Case numbers peaked in the warmer spring and summer months. ConclusionThis is the first report for South America of myasis caused by C. hominivorax in feral swine. In contrast to myasis in cattle that can reach deep into host tissues, screwworms in feral swine tended to cause superficial infestation. Feral swine present challenges to control screwworms in endemic areas. Screwworm populations maintained by feral swine may contribute to human cases in rural areas of Uruguay, which highlights the One Health importance of this invasive species-ectoparasite interaction.

scholarly journals Thermal Analisys of the Increase in Ambient Temperature Due to Motor Vehicle Activities

2019 ◽  
Vol 9 (2) ◽  
pp. 751-754
Keyword(s):  
Global Warming ◽  
Ambient Temperature ◽  
Motor Vehicle ◽  
The Body ◽  
Motor Vehicles ◽  
Living Things ◽  
Urban Heat ◽  
Specific Material ◽  
Temperature Heating ◽  
Earth Temperature

Global warming has become a problem of world wide, because it endangers living things. The consequences of global warming include the increase of the earth temperature and climate change. The increase of temperature (heating) in a city which is referred to urban heat island (UHI) is also the same problem in architecture. This research aimed to analyze the ambienttemperature of the UHI due to the motor vehicleactivities. Samples were taken from several locations: (1) Bahu Mall Parking area; (2) Manado Town Square 2 parking area; (3) along the Wolter Monginsidi street in front of Bahu Mall and (4) along the Piere Tendean street in front of Manado Town Square. This research used a quantitative method with a field survey. This research found that the ambient temperature increased when motor vehicles were stationary with engine on or moved. The temperature increased due to the heat from the engine and the reflection of the sun’s heat from the body of the vehicles. The heat level obtained from the survey was 34,8 0C to 39,4 0C. For this reason, a specific material for vehicle’s body is needed to prevent the increase of ambient temperature.

Impact of Aging on Distal Tibia Metaphysis Diameter

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Astolfi RS ◽  
◽  
Batista AV ◽  
Santos ALM ◽  
Leite JAD ◽  
...  
Keyword(s):  
Distal Tibia ◽  
The Body ◽  
Economic Viability ◽  
Average Height ◽  
Age Related ◽  
Bone Changes ◽  
Student’S T ◽  
The Many ◽  
Cortical Drift ◽  
Student’S T Test

One of the many bone changes that occur with aging is “cortical drift”, the absorption and deposition of bone on the endosteal and periosteal side, respectively, which results in bone enlargement in some but not all metaphyses. The distal tibia is one of the most fractured sites in the body and where anatomically shaped implants are mostly used. The economic viability of these implants depends on the maintenance of bone contour throughout life. MRI sagittal ankle images from 422 patients aged 18 to 100 years were analyzed and total distal tibia diameter measured. No correlation was observed between the parameters age and distal tibia diameter (Pearson-0.099), or when individuals were separated by sex (Pearson-0.021 for men and 0.049 for women). When separated by age, patients younger and older than 60 years old had a similar average height (1.65 and 1.62 m, respectively, student’s t- test = 0). This is the first study to evaluate possible age-related distal tibia enlargement. Bone changes with age do not result in distal tibia enlargement and possibly the majority of anatomically shaped bone implants are suitable irrespective of age.

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