scholarly journals Mosquitofish avoid thermal stress by moving from open water to the shade of the mangrove Rhizophora mangle

2020 ◽  
Vol 637 ◽  
pp. 103-116
Author(s):  
IW Hendy ◽  
O Burt ◽  
S Clough ◽  
L Young ◽  
SM Cragg
Keyword(s):  
Thermal Stress ◽  
Thermal Stresses ◽  
Rhizophora Mangle ◽  
Open Water ◽  
Direct Access ◽  
Maximum Temperature ◽  
Mangrove Forests ◽  
Ocean Water ◽  
Mature Adults ◽  
Large Numbers

Mangrove trees provide environmental buffering for animals by reducing daytime water thermal maxima. Shade from Rhizophora mangle trees reduces thermal stress for the mosquitofish Gambusia affinis. Data were collected from mangrove forests in Quintana Roo, Mexico, at 2 sites: (1) Soliman Bay, a mangrove forest decoupled from direct ocean water, and (2) La Lunita with semi-direct access to ocean water. During cooler morning hours at Soliman Bay, large numbers of mosquitofish foraged in open channels. At the same time, few mosquitofish utilised shaded areas within the R. mangle prop roots. When channels exceeded water temperatures above 38°C, mosquitofish migrated into the shaded areas provided by R. mangle trees. Channel water reached a daytime maximum temperature of 46°C, while daytime-shaded R. mangle areas remained 6.2°C cooler. Temperature rise and abundance shifts were not found in La Lunita, which has water temperatures of 27 to 28°C throughout the day. Size distributions between both localities showed mosquitofish caught in Soliman Bay to be >10% smaller than the mosquitofish from La Lunita, which had a greater abundance of mature adults. In Soliman Bay, mosquitofish were small, and the thermal stresses may impose serious developmental impacts that would be reduced by occupying water shaded by R. mangle. Refuge from R. mangle provides environmental buffering for fish, and future increasing water temperatures may reveal a greater use of this little-known mechanism. This study provides an example of a mechanism whereby mangroves support intertidal biodiversity through environmental buffering.

Studies on Beetles of the Family Ptinidae. VI.—The Biology of Ptinus fur (L.) and P. sexpunctatus Panzer

1951 ◽  
Vol 42 (3) ◽  
pp. 499-511 ◽  
Author(s):  
R. W. Howe ◽  
H. D. Burges
Keyword(s):  
Rapid Development ◽  
Maximum Temperature ◽  
Continuous Series ◽  
Optimum Temperature ◽  
Emergence Period ◽  
Mature Adults ◽  
Large Numbers ◽  
The Family ◽  
The Mean ◽  
Pass Through

The development of Ptinus fur (L.) and P. sexpunctatus Panzer at 70 per cent. R.H. and several temperatures has been studied.The optimum temperature for rapid development of P. fur is about 23°C., at which temperature it completes its development in a mean period of 132·1 days on fishmeal. For P. sexpunctatus the optimum temperature for rapid development is slightly below 30°C., development being completed in approximately 111 days on wheatfeed at this temperature.Eggs of P. sexpunctatus, but not those of P. fur, hatch at 30°C., which is near the maximum temperature for development of P. fur.Larvae of P. fur normally moult three times at 23°C. on fishmeal, but some have an extra moult.Well defined diapause as mature larvae in cocoons occurs at low temperatures in some individuals of P. fur ; at 23°C. this lasts about 220 days after normal larvae have pupated ; the period at 20°C. is about 280 days. Diapause at this stage also occurs in P. sexpunctatus. In experiments, the development periods of the diapausing and non-diapausing larvae overlapped to form a continuous series.Some P. sexpunctatus pass through a period of quiescence as mature adults in cocoons ; at 23°C., this lasted 43·5 days on fishmeal and 103·0 days on wheatfeed (mean periods). In P. fur the pre-emergence period is 30 to 60 days, considerably longer than that of other warehouse Ptinids studied.Of the foods, wheatfeed allows the quickest development for both species, but fishmeal produces the heaviest beetles.The adult beetles live for several months. They require food and drinking water. Egg output is small, the mean number of eggs laid per female at 25°C. being 38·6 for P. fur and 21·3 for P. sexpunctatus.P. sexpunctatus was able to overwinter in an unheated outbuilding and could possibly become a pest on some foods.P. fur is unlikely to occur in large numbers, owing to its long development period, small egg output and tendency to larval diapause.

Three Turnaround Heat Treating Studies

2003 ◽  
Author(s):  
Jaan Taagepera ◽  
Marty Clift ◽  
D. Mike DeHart ◽  
Keneth Marden
Keyword(s):  
Heat Treatment ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Heat Treating ◽  
Element Analysis ◽  
Stress Profiles ◽  
Insight Into

Three vessel modifications requiring heat treatment were analyzed prior to and during a planned turnaround at a refinery. One was a thick nozzle that required weld build up. This nozzle had been in hydrogen service and required bake-out to reduce the potential for cracking during the weld build up. Finite element analysis was used to study the thermal stresses involved in the bake-out. Another heat treatment studied was a PWHT of a nozzle replacement. The heat treatment band and temperature were varied with location in order to minimize cost and reduction in remaining strength of the vessel. Again, FEA was used to provide insight into the thermal stress profiles during heat treatment. The fmal heat treatment study was for inserting a new nozzle in a 1-1/4Cr-1/2Mo reactor. While this material would ordinarily require PWHT, the alteration was proposed to be installed without PWHT. Though accepted by the Jurisdiction, this nozzle installation was ultimately cancelled.

Steady-State Thermal Stresses in Wedge-Shaped Cutting Tools

1975 ◽  
Vol 97 (3) ◽  
pp. 1060-1066
Author(s):  
P. F. Thomason
Keyword(s):  
Thermal Stress ◽  
Steady State ◽  
Metal Cutting ◽  
Thermal Stresses ◽  
Heat Conduction Problem ◽  
Equivalent Stress ◽  
Cutting Tools ◽  
Thermoelastic Stress ◽  
Plastic State ◽  
Steady State Heat

Closed form expressions for the steady-state thermal stresses in a π/2 wedge, subject to constant-temperature heat sources on the rake and flank contact segments, are obtained from a conformal mapping solution to the steady-state heat conduction problem. It is shown, following a theorem of Muskhelishvili, that the only nonzero thermal stress in the plane-strain wedge is that acting normal to the wedge plane. The thermal stress solutions are superimposed on a previously published isothermal cutting-load solution, to give the complete thermoelastic stress distribution at the wedge surfaces. The thermoelastic stresses are then used to determine the distribution of the equivalent stress, and this gives an indication of the regions on a cutting tool which are likely to be in the plastic state. The results are discussed in relation to the problems of flank wear and rakeface crater wear in metal cutting tools.

Modelling of Convective Melt Flow and Interface Shape in Commercial Bridgman-Stockbarger Growth of CdZnTe

2000 ◽  
Author(s):  
Toby D. Rule ◽  
Ben Q. Li ◽  
Kelvin G. Lynn
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Solute Transport ◽  
Latent Heat ◽  
Thermal Stresses ◽  
Radiation Detector ◽  
Time History ◽  
High Quality ◽  
Melt Convection ◽  
The Impact

Abstract CdZnTe single crystals for radiation detector and IR substrate applications must be of high quality and controlled purity. The growth of such crystals from a melt is very difficult due to the low thermal conductivity and high latent heat of the material, and the ease with which dislocations, twins and precipitates are introduced during crystal growth. These defects may be related to solute transport phenomena and thermal stresses associated with the solidification process. As a result, production of high quality material requires excellent thermal control during the entire growth process. A comprehensive model is being developed to account for radiation and conduction within the furnace, thermal coupling between the furnace and growth crucible, and finally the thermal stress fields within the growing crystal which result from the thermal conditions imposed on the crucible. As part of this effort, the present work examines the heat transfer and fluid flow within the crucible, using thermal boundary conditions obtained from experimental measurements. The 2-D axisymetric numerical model uses the deforming finite element method, with allowance made for melt convection, solidification with latent heat release and conjugate heat transfer between the solid material and the melt. Results are presented for several stages of growth, including a time-history of the solid-liquid interface (1365 K isotherm). The impact of melt convection, thermal end conditions and furnace temperature gradient on the growth interface is evaluated. Future work will extend the present model to include radiation exchange within the furnace, and a transient analysis for studying solute transport and thermal stress.

scholarly journals Measurement and Isolation of Thermal Stress in Silicon-On-Glass MEMS Structures

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2603 ◽  
Author(s):  
Zhiyong Chen ◽  
Meifeng Guo ◽  
Rong Zhang ◽  
Bin Zhou ◽  
Qi Wei
Keyword(s):  
Thermal Stress ◽  
Natural Frequency ◽  
Frequency Conversion ◽  
Thermal Stresses ◽  
Sensors And Actuators ◽  
Stress Variation ◽  
Rigid Frame ◽  
Measured Stress ◽  
Stress Isolation ◽  
Frequency Variations

The mechanical stress in silicon-on-glass MEMS structures and a stress isolation scheme were studied by analysis and experimentation. Double-ended tuning forks (DETFs) were used to measure the stress based on the stress-frequency conversion effect. Considering the coefficients of thermal expansion (CTEs) of silicon and glass and the temperature coefficient of the Young’s modulus of silicon, the sensitivity of the natural frequency to temperature change was analyzed. A stress isolation mechanism composed of annular isolators and a rigid frame is proposed to prevent the structure inside the frame from being subjected to thermal stresses. DETFs without and with one- or two-stage isolation frames with the orientations <110> and <100> were designed, the stress and natural frequency variations with temperature were simulated and measured. The experimental results show that in the temperature range of −50 °C to 85 °C, the stress varied from −18 MPa to 10 MPa in the orientation <110> and −11 MPa to 5 MPa in the orientation <100>. For the 1-stage isolated DETF of <110> orientation, the measured stress variation was only 0.082 MPa. The thermal stress can be mostly rejected by a stress isolation structure, which is applicable in the design of stress-sensitive MEMS sensors and actuators.

Numerical Study of Thermal Stresses in a Planar Solid Oxide Fuel Cell Stack

2017 ◽  
Author(s):  
Cun Wang ◽  
Tao Zhang ◽  
Cheng Zhao ◽  
Jian Pu
Keyword(s):  
Thermal Stress ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Thermal Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Numerical Study ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Compressive Loads ◽  
Cte Mismatch

A three dimensional numerical model of a practical planar solid oxide fuel cell (SOFC) stack based on the finite element method is constructed to analyze the thermal stress generated at different uniform temperatures. Effects of cell positions, different compressive loads, and coefficient of thermal expansion (CTE) mismatch of different SOFC components on the thermal stress distribution are investigated in this work. Numerical results indicate that the maximum thermal stress appears at the corner of the interface between ceramic sealants and cells. Meanwhile the maximum thermal stress at high temperature is significantly larger than that at room temperature (RT) and presents linear growth with the increase of operating temperature. Since the SOFC stack is under the combined action of mechanical and thermal loads, the distribution of thermal stress in the components such as interconnects and ceramic sealants are greatly controlled by the CTE mismatch and scarcely influenced by the compressive loads.

scholarly journals Numerical Simulation Study on the Front Shape and Thermal Stresses in Growing Multicrystalline Silicon Ingot: Process and Structural Design

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1053
Author(s):  
Chengmin Chen ◽  
Guangxia Liu ◽  
Lei Zhang ◽  
Guodong Wang ◽  
Yanjin Hou ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Simulation Method ◽  
Power Ratio ◽  
Radial Temperature ◽  
Front Shape ◽  
Simulation Results ◽  
Insulation Block ◽  
Transient Numerical Simulation

In this paper, a transient numerical simulation method is used to investigate the effects of the two furnace configurations on the thermal field: the shape of the melt–crystal (M/C) interface and the thermal stress in the growing multicrystalline ingot. First, four different power ratios (top power to side power) are investigated, and then three positions (i.e., the vertical, angled, and horizontal positions) of the insulation block are compared with the conventional setup. The power ratio simulation results show that with a descending power ratio, the M/C interface becomes flatter and the thermal stress in the solidified ingot is lower. In our cases, a power ratio of 1:3–1:4 is more feasible for high-quality ingot. The block’s position simulation results indicate that the horizontal block can more effectively reduce the radial temperature gradient, resulting in a flatter M/C interface and lower thermal stress.

scholarly journals An Elastoplastic Thermal-Stress Analysis of a Free Plate

1956 ◽  
Vol 23 (3) ◽  
pp. 395-402
Author(s):  
Jerome Weiner
Keyword(s):  
Thermal Stress ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Uniqueness Theorem ◽  
Unique Solution ◽  
Heat Input ◽  
Thermal Stresses ◽  
Elastoplastic Material ◽  
Heuristic Solution ◽  
Peak Magnitude

Abstract The thermal stresses in a free plate of elastoplastic material subjected to a varying heat input over one face are determined. A heuristic solution is first found by suitable modifications of the known elastic solution. It is then verified that the solution satisfies all the conditions of the appropriate uniqueness theorem and represents therefore the unique solution to the problem. Residual stresses are determined and found to depend markedly on the peak magnitude of the heat input.

scholarly journals FINITE ELEMENT ANALYSIS OF THE HEAT TRANSFER IN A PISTON

2020 ◽  
Vol 4 (1) ◽  
pp. 45-51
Author(s):  
Aisha Muhammad ◽  
Shanono Ibrahim Haruna
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Numerical Simulations ◽  
Internal Combustion Engines ◽  
Thermal Stresses ◽  
Maximum Temperature ◽  
Cylinder Wall ◽  
Fe Model ◽  
Piston Cylinder ◽  
Piston Head

The gas expansion process that takes place in a piston cylinder assembly have been used in numerous applications. However, the time-dependent process of heat transfer is still not fully apprehended as the expansion processes are complex and difficult due to the unsteady property of the turbulent flow process. Internal combustion Engines(ICE) designs are conducted with the aim of achieving higher efficiency in the thermal characteristics. To optimize these designs, numerical simulations are conducted. However, modelling of the process in terms of heat transfer and combustion is complex and challenging. For a designer to understand, calculate and quantify the thermal stresses and heat losses at different sections of the structure, understanding the piston-cylinder wall is needed. This study carried out a numerical simulations based on Finite Element Method (FEM) to investigatethe stresses in the piston, and temperature after loading. Appropriate boundary conditions were set on different surfaces for FE model. The study includes the effects of the thermal conductivity of the material of piston, cylinder wall, and connecting rod. Results show the maximum Von-misses stress occurs on the piston head with a value of 3486. 1MPa. The maximum temperature of the piston head and cylinder wall stands at 68.252 and 42.704 degree Celsius respectively.

Thermal Stress of Blast Furnace Hearth Linings under Erosion State

2009 ◽  
Vol 16-19 ◽  
pp. 1101-1105 ◽  
Author(s):  
Liang Yu Chen ◽  
Yu Li ◽  
Jian Hua Gui
Keyword(s):  
Blast Furnace ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Convective Heat Transfer Coefficient ◽  
Calculation Model ◽  
Furnace Hearth ◽  
Blast Furnace Hearth ◽  
Cooling Intensity ◽  
Thermal Stress Concentration ◽  
Long Life

The structure of cooling stave was simplified with equivalent convective heat transfer coefficient, and the thermal stress axisymmetric calculation model of blast furnace hearth linings under erosion state was established. The thermal stresses of familiar erosion states were analyzed. The thermal stress concentration of erosion part is an importance cause of erosion development. ‘Elephant-foot’ erosion seldom develops to ‘boiler-bottom’ erosion. ‘Boiler-bottom’ erosion is a ideal long life erosion state. When the erosion stabilizes, smaller cooling intensity is favorable to linings stabilization.

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