scholarly journals Impact of operational temperature changes and freeze–thaw cycles on the hydraulic conductivity of borehole heat exchangers

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Jan-Henrik Kupfernagel ◽  
Jan Christopher Hesse ◽  
Markus Schedel ◽  
Bastian Welsch ◽  
Hauke Anbergen ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Hydraulic System ◽  
Coefficient Of Thermal Expansion ◽  
System Optimization ◽  
Cross Sectional ◽  
Pipe Surface ◽  
Thermally Induced ◽  
Pipe System ◽  
Freeze Thaw ◽  
System Integrity

AbstractA large share of the primary energy is consumed to provide space heating. Geothermal energy offers a regenerative alternative. For reasons of efficiency and environmental protection, it is important to ensure the system integrity of a borehole heat exchanger (BHE). Previous investigations have focused on the individual components of the BHE or on the grout and pipe systems’ integrity. This study focused on the analysis of the hydraulic system integrity of the complete subsoil–grout–pipe system as well as possible thermally induced changes. For this purpose, a pilot-scale experiment was built to test a 1-m section of a typical BHE under in situ pressure, hydraulic and temperature conditions. During the tests the hydraulic system permeability of the soil and the BHE was measured continuously and separately from each other. In addition, the temperature monitoring array was installed in a 50-cm cross-sectional area. Significant temperature-related fluctuations in the sealing performance could be observed. Hydraulic conductivity limits required by VDI 4640-2 (Thermal use of the underground—ground source heat pump systems, 2019) were exceeded without frost action. The succeeding application of freeze–thaw cycles further enhances the system permeability. The study shows that the thermally induced effects on the system integrity of the BHE are larger and more significant than the subsequent frost-induced effects. The hydrophobic character of the high-density polyethylene (PE-HD) pipes as well as its high coefficient of thermal expansion seem to be the main points of weakness in the system. Optimization research should focus on the interface connection between grout and pipe, whereby hydrophilic pipe materials such as stainless steel or aluminum should also be considered as well as manipulation of the pipe surface properties of PE-HD.

scholarly journals Plant Foods Rich in Antioxidants and Human Cognition: A Systematic Review

Antioxidants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 714
Author(s):  
Luciana Baroni ◽  
Anna Rita Sarni ◽  
Cristina Zuliani
Keyword(s):  
Young Adult ◽  
Human Cognition ◽  
Cognitive Assessments ◽  
Cross Sectional ◽  
Cognitive Domains ◽  
Plant Foods ◽  
Beneficial Effects ◽  
System Integrity ◽  
Plant Antioxidants ◽  
The Impact

Oxidative stress can compromise central nervous system integrity, thereby affecting cognitive ability. Consumption of plant foods rich in antioxidants could thereby protect cognition. We systematically reviewed the literature exploring the effects of antioxidant-rich plant foods on cognition. Thirty-one studies were included: 21 intervention, 4 cross-sectional (one with a cohort in prospective observation as well), and 6 prospective studies. Subjects belonged to various age classes (young, adult, and elderly). Some subjects examined were healthy, some had mild cognitive impairment (MCI), and some others were demented. Despite the different plant foods and the cognitive assessments used, the results can be summarized as follows: 7 studies reported a significant improvement in all cognitive domains examined; 19 found significant improvements only in some cognitive areas, or only for some food subsets; and 5 showed no significant improvement or no effectiveness. The impact of dietary plant antioxidants on cognition appears promising: most of the examined studies showed associations with significant beneficial effects on cognitive functions—in some cases global or only in some specific domains. There was typically an acute, preventive, or therapeutic effect in young, adult, and elderly people, whether they were healthy, demented, or affected by MCI. Their effects, however, are not attributable only to anti-oxidation.

Application of an Epoxy Cap in a Flip-Chip Package Design

1989 ◽  
Vol 111 (1) ◽  
pp. 16-20 ◽  
Author(s):  
E. Suhir
Keyword(s):  
Thermal Expansion ◽  
Flip Chip ◽  
Coefficient Of Thermal Expansion ◽  
Preliminary Test ◽  
Elastic Stability ◽  
Thermally Induced ◽  
Package Design ◽  
Silicone Gels ◽  
Low Modulus ◽  
Supporting Frame

In order to combine the merits of epoxies, which provide good environmental and mechanical protection, and the merits of silicone gels, resulting in low stresses, one can use an encapsulation version, where a low modulus gel is utilized as a major encapsulant, while epoxy is applied as a protecting cap. Such an encapsulation version is currently under consideration, parallel with a metal cap version, for the Advanced VLSI package design which is being developed at AT&T Bell Laboratories. We recommend that the coefficient of thermal expansion for the epoxy be somewhat smaller than the coefficient of thermal expansion for the supporting frame. In this case the thermally induced displacements would result in a desirable tightness in the cap/frame interface. This paper is aimed at the assessment of stresses, which could arise in the supporting frame and in the epoxy cap at low temperatures. Also, the elastic stability of the cap, subjected to compression, is evaluated. The calculations were executed for the Advanced VLSI package design and for a Solder Test Vehicle (STV), which is currently used to obtain preliminary information regarding the performance of the candidate encapsulants. It is concluded that in order to avoid buckling of the cap, the latter should not be thinner than 15 mils (0.40 mm) in the case of VLSI package design and than 17.5 mils (0.45 mm) in the case of STV. At the same time, the thickness of the cap should not be greater than necessary, both for smaller stresses in the cap and for sufficient undercap space, required for wirebond encapsulation. The obtained formulas enable one to evaluate the actual and the buckling stresses. Preliminary test data, obtained by using STV samples, confirmed the feasibility of the application of an epoxy cap in a flip-chip package design.

scholarly journals Evaluating hospital information system according to ISO 9241 part 12

2020 ◽  
Vol 6 ◽  
pp. 205520762097946
Author(s):  
Mahdieh Montazeri ◽  
Reza Khajouei ◽  
Mitra Montazeri
Keyword(s):  
Information System ◽  
Information Systems ◽  
Hospital Information System ◽  
System Optimization ◽  
Cross Sectional Study ◽  
Ease Of Use ◽  
Medical Sciences ◽  
Color Coding ◽  
Cross Sectional

Objectives Compliance with standards in designing information systems leads to better utilization and ease of use for users. In this study, the compliance of a widely used hospital information system (HIS) with ISO 9241 part 12 was assessed. Methods This applied research is a descriptive, cross-sectional study in which the HIS of 8 hospitals affiliated with Kerman University of Medical Sciences was evaluated based on ISO 9241 part 12. Data were collected by using ISO 9241/12 checklist. The data was analyzed in SPSS 16 using descriptive statistics. Results The analysis of data showed that the total compliance of the software with the ISO 9241/12 was 72%. The compliance of the software based on different groups of recommendations was 79% with Organization of information, 91% with Graphic objects, and 58% with Coding techniques. Compliance with different subgroups of ISO recommendations ranged from 28% related to “color coding” in coding techniques to 97% related to “General recommendation for graphical objects” in Graphic objects. Conclusion According to this study, the design of a widely used HIS has fairly good compliance with the standard but still suffers from some problems. Considering the role of accurate, valid and timely information in management of the hospitals, and the difficulty of system optimization after implementation, it is necessary that software developers follow existing standards when designing health information systems.

Substrate freeze–thaw in a drained Alberta fen

1989 ◽  
Vol 19 (8) ◽  
pp. 1024-1029 ◽  
Author(s):  
L. E. Swanson ◽  
R. L. Rothwell
Keyword(s):  
Hydraulic Conductivity ◽  
Significant Delay ◽  
Freeze Thaw ◽  
Sample Points ◽  
Surface Peat

The study of ground frost levels in a drained and undrained forested fen showed a significant delay in thaw as well as lower temperatures at 40 and 60 cm depths in the drained area because of the insulating effect of drier surface peat in the drained area. The undrained area froze to greater depths than the drained area, but thawed more rapidly. Ice was present year-round at 16.7% of the sample points in the portion of the drained area of low hydraulic conductivity. Thickness of the frozen layer appeared to be related to hydraulic conductivity as well as drainage. Thawing from underneath the frozen layer accounted for 38% of total thaw in the undrained area.

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