scholarly journals Analiz issledovanii vysokotemperaturnogo frettinga primenitel'no k razrabotke innovatsionnykh reshenii povysheniia nadezhnosti mashin

2020 ◽  
pp. 114-125
Author(s):  
Valerii Vasilevich Alisin
Keyword(s):  
High Temperatures ◽  
Spectral Composition ◽  
Effect Of Temperature ◽  
Friction Contact ◽  
Force Analysis ◽  
Wear Process ◽  
Actual Contact ◽  
Innovative Solutions ◽  
Machine Elements ◽  
Physical And Chemical

The article is devoted to the development of the direction of work on the creation of qualitatively new innovative solutions to ensure the reliability of connections of machine elements. The recommendations are based on the analysis of studies on wear process of the fixed joints of machine elements during microdisplacements in contact under the influence of vibration at high temperatures. It is established that physical and chemical processes occurring in the area of actual contact of the joint elements are varied and the effect of temperature on tribological characteristics of frictional contact is complex, since with an increase in temperature the reduction of worn-out volume can occur as well as increase of it. To predict the resistance of the contact to fretting, it is necessary to conduct a force analysis on the contact and determine the spectral composition of vibrations affecting the friction contact.

scholarly journals DFT calculation for the electronic properties and quantum capacitance of pure and doped Zr2CO2 as electrode of supercapacitors

2021 ◽  
Author(s):  
Shuo Xu ◽  
Shi-Jie Wang ◽  
Li Xiao-Hong ◽  
Hong-Ling Cui
Keyword(s):  
Electronic Properties ◽  
Electrode Materials ◽  
Chemical Properties ◽  
Effect Of Temperature ◽  
Quantum Capacitance ◽  
Substitutional Site ◽  
Level Shifts ◽  
Dirac Distribution ◽  
Increasing Temperature ◽  
Physical And Chemical

Defect and doping are effective methods to modulate the physical and chemical properties of materials. In this report, we investigated the structural stability, electronic properties and quantum capacitance (Cdiff) of Zr2CO2 by changing the dopants of Si, Ge, Sn, N, B, S and F in the substitutional site. The doping of F, N, and S atoms makes the system undergo the semiconductor-to-conductor transition, while the doping of Si, Ge, and Sn maintains the semiconductor characteristics. The Cdiff of the doped systems are further explored. The B-doped system can be used as cathode materials, while the systems doped by S, F, N, Sn atoms are promising anode materials of asymmetric supercapacitors, especially for the S-doped system. The improved Cdiff mainly originates from Fermi-level shifts and Fermi-Dirac distribution by the introduction of the dopant. The effect of temperature on Cdiff is further explored. The result indicates that the maximum Cdiff of the studied systems gradually decreases with the increasing temperature. Our investigation can provide useful theoretical basis for designing and developing the ideal electrode materials for supercapacitors.

Temperature-induced pupil movements in insect superposition eyes

2000 ◽  
Vol 203 (4) ◽  
pp. 685-692 ◽  
Author(s):  
P. Nordstrom ◽  
E.J. Warrant
Keyword(s):  
High Temperatures ◽  
Cydia Pomonella ◽  
Codling Moth ◽  
Light Level ◽  
Agrotis Segetum ◽  
Effect Of Temperature ◽  
Activation Temperature ◽  
Ambient Light Level ◽  
Wide Range ◽  
Response To Temperature

In this paper, we describe the hitherto largely overlooked effect of temperature on the pupil of insect compound eyes. In the turnip moth Agrotis segetum and in two other nocturnal insects with superposition eyes, the lacewing Euroleon nostras and the codling moth Cydia pomonella, the pupil not only opens and closes with changes in the ambient light level, as expected, but also with changes in temperature in the absence of light. In complete darkness, the pupil of A. segetum responds over a wide range of temperatures, with the pupillary pigments migrating to a light-adapted position when the animal is exposed to either low or high temperatures. At temperatures between 21.0 and 22.7 C, the pigments migrate to the fully dark-adapted position, resulting in an open pupil and maximal eye glow. Pupil closure at high temperatures shows two distinct thresholds: the first at 23.8+/−0.7 C and a second some degrees higher at 25.7+/−1.2 C (means +/− s.d., N=10). Temperatures exceeding the first threshold (the activation temperature, T(a)) initiate a closure of the pupil that is completed when the temperature exceeds the second threshold (the closure temperature, T(c)), which causes rapid and complete migration of pigment to the light-adapted position. All temperatures above T(a) affect the pupil, but only temperatures exceeding T(c) result in complete closure. Temperatures between T(a) and T(c) cause a slow, partial and rather unpredictable closure. The lacewing and the codling moth both show very similar responses to those of A. segetum, suggesting that this response to temperature is widespread in superposition eyes. The possibility that the ambient temperature could be used to pre-adapt the eye to different light intensities is discussed.

scholarly journals The effect of temperature upon radioactive disintegration

1912 ◽  
Vol 86 (586) ◽  
pp. 240-253 ◽  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Systematic Investigation ◽  
Effect Of Temperature ◽  
Active Matter ◽  
Radium Emanation ◽  
Γ Rays ◽  
Method Of Measurement ◽  
Positive Effect

Within the last few years the influence of high temperature on the activity of radium emanation, of the active deposit, and of radium C has been examined in detail by several authors. The conclusions arrived at have been conflicting, some workers affirming a positive effect of tem­perature, others denying it. This lack of agreement is due, however, to a difference in the method of measurement of the active matter under investigation. Those workers who measured the activity by γ-rays are all agreed that temperature has no effect whatever, while those who measured by β-rays found always an effect of some kind, in many cases of considerable magnitude, and often, indeed, of a very surprising nature. While, however, the fact that there is a β-ray effect is admitted by all, there is still a lack of agreement between the results of the experiments of different workers, and even of different experiments of the same worker, which is hardly to be expected if the effects were due to a definite change in the properties of the disintegrating atoms at high temperatures. In view, therefore, of the uncertainty which has arisen on a point of such great theoretical importance, a systematic investigation was necessary to obtain definite results, whether positive or negative. This the author, at the request of prof. Rutherford, has carried out.

Effect of temperature and moist conditions on seed dormancy cycling of two sympatric limestone species, Begonia guishanensis and Paraisometrum mileense, in southern China

2020 ◽  
Vol 30 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Xiao-Jian Hu ◽  
Cheng Liu ◽  
Ai-Rong Li ◽  
Xiang-Yun Yang ◽  
Carol Baskin
Keyword(s):  
Field Experiment ◽  
High Temperatures ◽  
Seed Dormancy ◽  
Natural Environment ◽  
Southern China ◽  
Soil Seed Bank ◽  
Effect Of Temperature ◽  
Wet Season ◽  
Persistent Soil Seed Bank ◽  
Almost All

AbstractInformation about seed dormancy cycling and germination in relation to temperature and moisture conditions in the natural environment is important for the conservation and restoration of rare species, including Begonia guishanensis and Paraisometrum mileense, two sympatric perennial limestone (karst) species. Dry afterripening (DAR) and wet and dry (WD) cycles at 15/5 and 25/15°C as well as moist chilling (MC) at 15/5°C were used to mimic the natural environment at different times of the year. A field experiment was conducted to monitor seasonal changes in germination responses of the seeds. About 40–65% of B. guishanensis and 5% of P. mileense seeds were dormant at maturity. DAR at 25/15 and 15/5°C as well as MC and WD cycles at 15/5°C alleviated dormancy for B. guishanensis but not P. mileense, and WD cycles at 25/15°C induced a deeper conditional dormancy for both species. Seeds of B. guishanensis exhibited dormancy cycling in the field, with increased dormancy under natural WD cycles at relatively high temperatures during the transition from the dry to the wet season in April to May and decreased dormancy during the wet season from June to October. KNO3 mitigated the dormancy-inducing effect of both artificial and natural WD cycles at relatively high temperatures for B. guishanensis. The field experiment indicated that seeds of B. guishanensis may be able to form a persistent soil seed bank, while almost all seeds of P. mileense germinate at the beginning of the wet season in the field.

Effect of Temperature on Response of Tomatoes to Several Dinitroaniline Herbicides and Phosphorus

Weed Science ◽  
1976 ◽  
Vol 24 (1) ◽  
pp. 115-119 ◽  
Author(s):  
H. P. Wilson ◽  
F. B. Stewart ◽  
T. E. Hines
Keyword(s):  
High Temperatures ◽  
Phosphorus Content ◽  
Dry Weight ◽  
Field Studies ◽  
Effect Of Temperature ◽  
Controlled Environment ◽  
Effects Of Temperature ◽  
Environment Chamber ◽  
Chamber Studies ◽  
Dinitroaniline Herbicides

Effects of temperature on response of transplanted tomatoes (Lycopersicon esculentumMill. ‘Campbell 17′) to trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), nitralin [4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline], profluralin [N-(cyclopropylmethyl)-α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine], and isopropalin (2,6-dinitro-N,N-dipropylcumidine) were investigated in field studies. Trifluralin and nitralin caused greater reductions in growth and yields of tomatoes transplanted early in April than to tomatoes transplanted around May 1. Responses to profluralin were similar but total yields of early transplanted tomatoes were not reduced although initial yields were below those of tomatoes treated with isopropalin. In controlled environment chamber studies, percent phosphorus of plant tops was reduced by trifluralin at low temperatures but was not influenced by trifluralin at high temperatures. Tomoto responses to phosphorus as reflected by plant fresh weight, dry weight and phosphorus content (mg/plant) were reduced by trifluralin at low and high temperatures.

The Effect of Temperature on the Physical and Chemical Development of Cotton Fiber

1957 ◽  
Vol 27 (5) ◽  
pp. 412-416 ◽  
Author(s):  
Lyle E. Hessler ◽  
Carole R. Simmons ◽  
Harry C. Lane
Keyword(s):  
Cotton Fiber ◽  
Effect Of Temperature ◽  
Physical And Chemical

Temperature, Size and Egg Production in the Cabbage Butterfly, Pieris Rapae L.

1982 ◽  
Vol 30 (2) ◽  
pp. 223 ◽  
Author(s):  
RE Jones ◽  
JR Hart ◽  
GD Bull
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Egg Production ◽  
Pieris Rapae ◽  
Effect Of Temperature ◽  
Pupal Weight ◽  
Larval Diet ◽  
Young Females ◽  
Rearing Conditions ◽  
High Degree

Larvae reared at low temperatures produce larger pupae and adults than those reared at high temperatures, and pupal weight is linearly related to lifetime egg production; mean egg production in a group reared at 29-3l�C may be twice that of another reared at 17.5-19�C. The number of eggs visible with a dissecting microscope in the ovaries of young females is not proportional to their lifetime production. Once size is taken into account, there is no additional effect of temperature or larval diet on total egg production. The timing of egg production throughout an adult's life is unaffected by its size or by the conditions in which it was reared. but there are marked differences between Australian and Canadian (Vancouver) individuals. The size of eggs is inversely correlated with both the age and the size of the mother. In any particular set of rearing conditions, males tend to be larger than females, and the sexes show an equal and high degree of variation in size.

Properties of Hard Rubber. XVIII. Action of Hydrocarbon Oils at High Temperatures (Part XV of Swelling of Rubber)

1947 ◽  
Vol 20 (1) ◽  
pp. 171-172
Author(s):  
J. R. Scott
Keyword(s):  
Petroleum Ether ◽  
Plastic Flow ◽  
High Temperatures ◽  
Critical Value ◽  
Transformer Oil ◽  
Aliphatic Hydrocarbons ◽  
Effect Of Temperature ◽  
Pronounced Change ◽  
Noticeable Effect ◽  
Two Samples

Abstract It has already been shown that liquids consisting essentially of aliphatic hydrocarbons, e.g., petroleum ether, paraffin, and transformer oil, had practically no swelling action at 34° C on two samples of hard rubber composed of rubber and sulfur only. Hard rubber shows a pronounced change in properties at temperatures above a critical value (“yield temperature”) in the neighborhood of 50° –80° C, the most noticeable effect being that it becomes much softer and more susceptible to plastic flow. It seemed likely, therefore, that the swelling action of liquids such as those mentioned above might be much greater at temperatures above this critical value. This view was strengthened by the statement of Dunton and Muir that hard rubber is “badly attacked” by immersion for 7 days in “hot” transormer oil. As no data appear to have been published on the effect of temperature on the swelling of hard rubber, experiments were made to examine this effect. Details of the hard rubber samples used are as follows.

scholarly journals Mass wear application of cooperated elements for evaluation of friction pair components condition

2021 ◽  
Vol 351 ◽  
pp. 01006
Author(s):  
Maciej Matuszewski ◽  
Małgorzata Słomion ◽  
Adam Mazurkiewicz ◽  
Andrzej Wojciechowski
Keyword(s):  
Surface Layer ◽  
Surface Structure ◽  
Friction Pair ◽  
Experimental Tests ◽  
Wear Process ◽  
Machine Elements ◽  
Conformal Contact

In this study, the influence of the geometrical surface structure shape on wear process of friction pairs elements with conformal contact was analyzed. Characteristics of the machine elements surface layer were described with special distinction of importance of the surface structure directivity and isotropy in terms of the surface layer transformation. This work presents the results of experimental tests in which the following input factors were used: specimen and counter-specimen ridge angle of intersection (0°; 30°; 45°; 60°; 90°) and specimen and counter-specimen clamp (1.0; 1.5; 2.0 MPa). The changes of the surface layer were recorded as a function of a specimen mass changes. Based on the conducted research, it was found that the ridge angle of intersection on the specimen and counter-specimen has a significant impact on the wear process intensity. The changes were uttermost for 0° angle and slightest for 9°. It was also found that the observed changes have a larger gradient for higher specimen load values. Thus, the significance of the geometrical surface structure directivity influence on the friction pair elements wear process intensity was confirmed.

Sign in / Sign up

Export Citation Format

Share Document