The rehabilitation of a passive-ventilated slab on grade foundation using horizontal thermosyphons

1998 ◽  
Vol 35 (4) ◽  
pp. 684-691 ◽  
Author(s):  
J K McKenna ◽  
K W Biggar
Keyword(s):  
Thermal Degradation ◽  
Soil Temperature ◽  
Thermal Regime ◽  
Ellesmere Island ◽  
Initial Problem ◽  
Foundation Settlement ◽  
Canadian Forces ◽  
Paper Briefly ◽  
Restricted Access ◽  
And Performance

Due to the plugging of the vents beneath a vented-slab concrete foundation of the Supply Building at Canadian Forces Station Alert on the northern tip of Ellesmere Island, excessive thermal degradation of the underlying permafrost caused unacceptable settlement of the slab. It was determined that maintenance of the existing system would be an ongoing problem and replacement of the structure would cost $3 million and 3 years to construct. To re-establish the thermal regime under the Supply Building, it was decided to use a newly developed horizontal thermosyphon system installed in the existing vents to rehabilitate the foundation. The thermosyphon installation presented some unique problems owing to the restricted access around the building and the requirement to drill horizontally beneath the building, which necessitated the fabrication of a special drill rig. In addition, the use of horizontally placed thermosyphons is a relatively new application of the existing technology. The paper briefly describes the initial problem, the development of the solution, and describes in detail the actual installation and performance of the horizontal thermosyphon system with 3 years of soil temperature data.Key words: permafrost, thermosyphon, foundation, settlement, ventilated slab, CFS Alert.

scholarly journals Characteristics and mechanical properties changes due to incorporation of aloe vera in polyethylene-based film

2020 ◽  
Vol 17 (2) ◽  
pp. 61
Author(s):  
Siti Fatma Abd Karim ◽  
Junaidah Binti Jai ◽  
Ku Halim Ku Hamid ◽  
Abdul Wafi Abdul Jalil
Keyword(s):  
Mechanical Properties ◽  
Thermal Degradation ◽  
Aloe Vera ◽  
Functional Materials ◽  
Chain Structure ◽  
Substantial Effect ◽  
Scanning Calorimetry ◽  
Degradation Temperature ◽  
And Performance ◽  
The Impact

Non-degradable properties of polyethylene (PE) films due to long-chain structure cause increment of solid waste plastic. Many researchers, with different purposes, have studied the incorporation of functional materials to PE. Studying the impact of incorporation of aloe vera (AV) into PE films in terms of its characteristic and mechanical properties is the main objective of this paper. The films were prepared using melt-blending and hot press technique. The characterization assessed for the PE and PE-AV films were spectroscopy, crystalline phase, thermal analysis and performance of mechanical properties of the sample.  The functional group detected in spectroscopy studied did not show any changes for PE film or PE with the presence of AV. Lower thermal degradation temperature (Td) obtained for PE-AV3 while others film found no significant changes of Td value and only one peak of thermal degradation occurred for all film. The same goes to the analysis obtained from differential scanning calorimetry (DSC) data. However, the crystalline structure displayed momentous peak changes for PE with AV. The highest tensile strength (TS) obtained by PE-AV3, at once developing highest value of Young’s modulus (YM), modulus of resilience (UE) and modulus of toughness (UT). A certain amount of AV has substantial effect on changing the polymeric structure especially improving the mechanical properties of PE film. Therefore, AV has potential to become an additive for developing a new partially degradable PE film.

Surface air–soil temperature relationship and shallow soil thermal regime: a case study using a soil temperature observational dataset for Spain.

2021 ◽  
Author(s):  
Camilo Melo Aguilar ◽  
Fidel González Rouco ◽  
Norman Steinert ◽  
Elena García Bustamante ◽  
Felix García Pereira ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Soil Temperature ◽  
Air Temperature ◽  
Thermal Regime ◽  
Ground Surface ◽  
Surface Air Temperature ◽  
Environmental Variable ◽  
Chemical Processes ◽  
Strong Connection ◽  
Shallow Subsurface

<p>The land-atmosphere interactions via the energy and water exchanges at the ground surface generally translate into a strong connection between the surface air temperature (SAT) and the ground surface temperature (GST). In turn, the surface temperature affects the amount of heat flowing into the soil, thus controlling the subsurface temperature profile. As soil temperature (ST) is a key environmental variable that controls various physical, biological and chemical processes, understanding the relationship between SAT and GST and STs is important.</p><p>In situ ST measurements represent the most adequate source of information to evaluate the distribution of temperature in soils and to address its influence on soil biological and chemical processes as well as on climate feedbacks. However, ST observations are scarce both in space and time. Therefore, the development of ST observational datasets is of great interest to promote analyses regarding the soil thermodynamics and the response to atmospheric warming.</p><p>We have developed a quality-controlled dataset of Soil Temperature Observations for Spain (SoTOS). The ST data are obtained from the Spanish meteorological agency (AEMET), including ST at different layers down to a depth of 1 m (i.e., 0.05, 0.1, 0.2, 0.5 and 1 m depth) for 39 observatories for the 1985–2018 period. Likewise, 2m air temperature has also been included for the same 39 sites.</p><p>SoTOS is employed to evaluate the shallow subsurface thermal regime and the SAT–GST relationship on interannual to multidecadal timescales. The results show that thermal conduction is the main heat transfer mechanism that controls the distribution of soil temperatures in the shallow subsurface. Regarding the SAT-GST relationship, there is a strong connection between SAT and GST. However, the SAT–GST coupling may be disrupted on seasonal to multidecadal timescales due to variations in the surface energy balance in response to decreasing soil moisture conditions over the last decade at some SoTOS sites. This results in larger GST warming relative to SAT. Such a response may have implications for climate studies that assume a strong connection between SAT and GST such as air temperature estimations from remote sensing products or even for palaeoclimatic analyses.</p>

A Modeling Approach to Simulate Effects of Intercropping and Interspecific Competition in Arable Crops

2012 ◽  
pp. 160-181
Author(s):  
Heike Knörzer ◽  
Simone Graeff-Hönninger ◽  
Bettina U. Müller ◽  
Hans-Peter Piepho ◽  
Wilhelm Claupein
Keyword(s):  
Solar Radiation ◽  
Soil Temperature ◽  
Interspecific Competition ◽  
Neighborhood Effects ◽  
Individual Growth ◽  
Beneficial Effects ◽  
Modeling Approaches ◽  
Use Efficiency ◽  
And Performance ◽  
Radiation Use

Interspecific competition between species influences their individual growth and performance. Neighborhood effects become especially important in intercropping systems, and modeling approaches could be a useful tool to simulate plant growth under different environmental conditions to help identify appropriate combinations of different crops while managing competition. This study gives an overview of different competition models and their underlying modeling approaches. To model intercropping in terms of neighbouring effects in the context of field boundary cultivation, a new model approach was developed and integrated into the DSSAT model. The results indicate the possibility of simulating general competition and beneficial effects due to different incoming solar radiation and soil temperature in a winter wheat/maize intercropping system. Considering more than the competition factors is important, that is, sunlight, due to changed solar radiation alone not explaining yield differences in all cases. For example, intercropped maize could compensate low radiation due to its high radiation use efficiency. Wheat benefited from the increased solar radiation, but even more from the increased soil temperature.

scholarly journals 551 STUDIES ON SEEDLING PRODUCTION OF ASPARAGUS UNDER DIFFERENT GROWTH CONDITIONS

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 510d-510
Author(s):  
Kh. A. Okasha ◽  
H. Gomma
Keyword(s):  
Soil Temperature ◽  
Soil Surface ◽  
Dry Weight ◽  
Growth Conditions ◽  
Asparagus Officinalis ◽  
Vegetable Growth ◽  
Plastic Mulching ◽  
And Performance ◽  
Propagation Methods ◽  
Significant Increment

This study was carded out on Asparagus (Asparagus officinalis L.) during the two successive seasons of 1987/1988 and 1988/1989 at the Agricultural Experimental Station of National Research Center at Shalakan Kaloubia Governorate The investigation was aimed to study the effect of cultivar, propagation methods and polyethylene mulching on plant growth and performance The application of plastic mulching caused signficant increases in plant height. number of shoots. number of branches, fern fresh and dry weight and roots an rhizome fresh and dry weight Covering the soil surface with black and transparent polyethylene enhanced the vegetable growth of asparagus plant significantly as compared with unmulched treatments. Mulching with transparent polyethylene increased soil temperature over black polyethylene mulch and both treatments were higher in soil temperature than the control. Concerning the variation existed among cultivars, UC 157 F1 showed a significant increment in vegetable growth compared with UC 157 F2.

scholarly journals Thermal behaviour and performance of two field experimental insulation covers to control sulfide oxidation at Meadowbank mine, Nunavut

2020 ◽  
Author(s):  
Vincent Boulanger-Martel ◽  
Bruno Bussière ◽  
Jean Côté
Keyword(s):  
Oxygen Consumption ◽  
Heat Conduction ◽  
Thermal Behaviour ◽  
Thermal Regime ◽  
Sulfide Oxidation ◽  
The Arctic ◽  
Storage Facility ◽  
Thermal Monitoring ◽  
Waste Rocks ◽  
And Performance

Insulation covers are an appealing reclamation approach to control sulfide oxidation in tailings storage facilities located in the Arctic. In this study, the thermal behaviour and effectiveness of insulation covers for the reclamation of the Meadowbank mine’s tailings storage facility were assessed using both laboratory-based tests and field experimental cells. Oxygen consumption tests performed in controlled laboratory conditions indicated that a temperature of 0 °C is adequate to control Meadowbank’s tailings oxidation. Two instrumented experimental covers were constructed with 2 and 4 m of non-reactive waste rocks. Thermal monitoring of the experimental cells was conducted over 4.5 years and demonstrated a thermal regime dominated by heat conduction. The 2-m cover displayed temperatures at the tailings-cover interface greater than 0 °C for 94 to 124 days per year, whereas the tailings under the 4-m cover stayed below 0 °C year-round. Field oxygen consumption tests showed a reduction of 70 to 90% in the oxygen uptakes measured for covered tailings compared to uncovered tailings. Calculations of yearly oxygen consumption fluxes showed oxygen fluxes less than 2 mol.m<sup>-2</sup>.yr<sup>-1</sup>, confirming the effectiveness of the cover configurations to control sulfide oxidation.

The Study of LC Three Point Oscillation Circuit Based on the Multisim Simulation Software

2014 ◽  
Vol 1028 ◽  
pp. 278-283
Author(s):  
De Yue Cao ◽  
Yang Zhang ◽  
Yi Zou
Keyword(s):  
Simulation Software ◽  
Performance Parameters ◽  
Paper Briefly ◽  
Oscillation Circuit ◽  
And Performance

This paper briefly introduces the function of LC three point oscillation circuit and the study of the composition and performance parameters of capacitance three point oscillation circuit, inductance three point oscillation circuit and modified capacitance three point oscillation circuit based on the Multisim simulation software.

The Application of GPC Algorithm on Network Predictive Control Based on Toeplitz Equation

2014 ◽  
Vol 651-653 ◽  
pp. 966-971
Author(s):  
Rao Bin
Keyword(s):  
Time Delay ◽  
Predictive Control ◽  
Basic Principle ◽  
Packet Loss ◽  
Control Algorithm ◽  
Paper Briefly ◽  
Signal Tracking ◽  
Model Mismatch ◽  
Operation Speed ◽  
And Performance

Network latency was usually uncertain or random, and the packet loss and temporal disorders could also be attributed to a certain degree of time delay. This paper briefly described the basic principle of predictive control and deduced the predictive control algorithm based on Toeplitz equation, finally combined with the simulation example to verify the validity and superiority of the new algorithm, from the operation speed of the algorithm, the signal tracking capabilities when time delay existed, and performance for overcoming the influence of model mismatch.

scholarly journals EFFECT OF SOIL SOLARIZATION ON THERMAL REGIME OF PLASTIC GREENHOUSE SOIL

1994 ◽  
Vol 24 (2) ◽  
pp. 229-233 ◽  
Author(s):  
Nereu Augusto Streck ◽  
Flavio Miguel Schneider ◽  
Galileo Adeli Buriol
Keyword(s):  
Soil Temperature ◽  
Edge Effect ◽  
Central Region ◽  
Thermal Regime ◽  
Rio Grande ◽  
Bare Soil ◽  
Low Density ◽  
Control Soil ◽  
Rio Grande Do Sul ◽  
Greenhouse Soil

SUMMARY Temperature modification in soil of plastic greenhouse caused by solarization was measured during the summer in the Subtropical Central Region of the Rio Grande do Sul State, Brazil. The experiment was carried out in a 10m x 25m greenhouse covered with low density transparent polyethylene (PE). Four 6m x 4m plots were mulched with 100µm thickness PE sheets, from December 12, 1992 to March 7, 1993. Four other plots (same size) without the cover were used as control (bare soil). Results indicated that solarization incrased the maximum soil temperature. The average was 11.9, 10.8, 9.8, and 8.6°C over uncovered control soil at 2, 5, 10, and 20cm depth, respectively. The soil temperature reached values of up to 54.4°C at 2cm and 50.2°C at 5cm depth. Temperatures exceeding 45°C and 50°C in solarized soil have also occurred in several days. "Edge effect" in mulched plots was also detected.

Grazing behaviour, intake and performance of dairy ewes with restricted access time to berseem clover (Trifolium alexandrinumL.) pasture

2016 ◽  
Vol 72 (2) ◽  
pp. 194-210 ◽  
Author(s):  
G. Molle ◽  
M. Decandia ◽  
V. Giovanetti ◽  
C. Manca ◽  
M. Acciaro ◽  
...  
Keyword(s):  
Access Time ◽  
Restricted Access ◽  
Dairy Ewes ◽  
Berseem Clover ◽  
And Performance ◽  
Grazing Behaviour
Sign in / Sign up

Export Citation Format

Share Document