• Title/Summary/Keyword: Gravity Effect

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Effect of gravity on a micropolar thermoelastic medium with voids under three-phase-lag model

  • Alharbi, Amnah M.;Othman, Mohamed I.A.;Al-Autabi, Al-Anoud M.Kh.
    • Structural Engineering and Mechanics
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    • v.76 no.5
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    • pp.579-590
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    • 2020
  • This paper's objective is to investigate the effect of gravity on a micropolar thermoelastic medium with voids. The problem is assessed according to the three-phase-lag model. An analysis of the resulting non-dimensional displacement, temperature variation, and internal stress of the study material is carried out and presented graphically. The non-dimensional displacement, temperature, micro-rotation, the change in the volume fraction field and stress of the material are obtained and illustrated graphically. Comparisons are made with the results predicted by different theories for different values of gravity, the phase-lag of the heat flux and the phase-lag of the temperature gradient. The numerical results reveal that gravity and relaxation times have a significant influence on the distribution of the field quantities. Some notable insights of interest are deduced from the investigation.

Gravity, Magnetic and VLF explorations in the ubong industrial waste landfill, Pohang (포항 유봉산업 폐기물 매립지에서의 중력, 자력, VLF 탐사)

  • 권병두
    • Economic and Environmental Geology
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    • v.32 no.2
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    • pp.177-187
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    • 1999
  • Gravity, magnetic and VLF surveys were conducted to investigat the structural stability and hazards associated with the Ubong landfill in Pohang City, which has been built to dump industrial wastes. In 1994, the collapse of a bank happened in the 6th landfill site due to sudden heavy rain, and a large quantity of waste materials flowed out to the nearby landfill sites, factories and roads. We used $10{\times}10m$ resolution DEM data for gravity reductions. The maximum variation of the terrain effect in the survey area is about 0.5 mgal and the terrain effect is large in the vicinity of bank boundary. The Bouguer gravity anomaly map shows the effect due to the variatino of thickness and type of waste materials. The small negative gravity anomaly increases from the 9th site to the 6th site. The small negative gravity anomaly of the 9th site reflects the relatively shallow dumping depth of average 14.5 m in this site and increased density of waste materials by the repeated stabilization process of soil overlaying. The 6th site is located at the center of the former valley and rainfall and groundwater are expected to flow from south-east to north-west. Therefore, considering the previous accident of mixing waste and bank materials at the north-west boundary of the landfill, there may be some environmental problems of leakage of contaminated water and bank stability. The complex inversion technique using Simulated annealing and Marquardt-Levenberg methods was applied to calculate three-dimensional density distribution from gravity data. In the case of 6th site, it is apparent that the landfill had been dumped in four sectors. However, most part of the 9th site and showed that high magnetic industrial wastes were concentrated in the 6th site. The result of magnetic survey showing low magnetic anomalies along the boundaries of two sites is similar to that of gravity data. The VLF data also reveals four divided sectors in the 6th site, and overall anomaly trend indicates the directio of former valley.

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Analysis of the Gravity Effect on the Distribution of Refrigerant Flow in a Multi-circuit Condenser (다분지 응축기의 냉매유량 분배에 미치는 중력의 영향을 고려한 해석방법)

  • Lee Jangho;Kim Moo Hwan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.12
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    • pp.1167-1174
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    • 2004
  • The method to consider gravity effect on the performance of a condenser is developed, and a simple condenser having 'nU' type two circuits is analyzed. Each circuit has the same length and inlet air-side operational conditions. The only difference between two circuits is the direction of refrigerant flow, which is exactly opposite each other between the upper 'n' type circuit and the lower 'U' type circuit. It is shown that the gravity makes the distribution of refrigerant flow uneven in the two circuits at lower refrigerant flow rates; heat transfer rate also becomes uneven. Moreover, much of the refrigerant exists as liquid state in the circuit having low refrigerant flow rate, which will make the cycle balance unstable in the refrigeration cycle system like a heat pump.

Using the pendulum column as an isolator by reducing the gravity effect

  • Abdallah Azizi;Majid Barghian
    • Earthquakes and Structures
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    • v.25 no.4
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    • pp.297-305
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    • 2023
  • The conventional method of structural seismic design was based on increasing structural capacity, which usually didn't reduce earthquake seismic effects. By changing the philosophy of structure design, technologies such as passive seismic control have been used in structures. So far, a large number of seismic isolation systems have been introduced to dissipate earthquake energy that is applied to a structure. These systems act against earthquakes rather than increasing the strength and capacity of the structure. In the present paper, a suspended column called a "pendulum column" is investigated, and a new idea has been considered to improve the performance of the pendulum column isolator by changing the gravity effect by adding a spring under the isolator system. The behavior of the studied isolator system has been researched. Then the isolator system was investigated under different earthquakes and compared with a common pendulum column isolator. The results show that changing the gravity effect has an effective role in the response of the system by reducing the system stiffness. Equations for the system showed that even in a special state, complete isolation is possible. Finally, the tested model verified the theory.

Effect of Egg gravity of Silkworm, Bombyx mori L., on the Hatching and the Practical Hatching Ratio (I) (잠난비중이 부화율에 미치는 영향 ( I ))

  • 손해용;김윤식
    • Journal of Sericultural and Entomological Science
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    • v.20 no.2
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    • pp.6-9
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    • 1978
  • This experiment was attempted to investigate the effect of the specific gravity of silkworm eggs on the hatching and the practical hatching ratio depend upon six egg production companies for two silkworm races and their reciprocal crosses. 1. The hatching and the practical hatching ratio in the specific gravity of medium and heavy eggs were higher than in the specific gravity of light eggs. 2. Compare with Japanese or Chinese mother races each other, it was inclined that the former seems to be higher than the latter on the hatching ratio in the specific gravity of light and medium eggs, but the practical hatching ratio was high only in the specific gravity of light eggs. 3. Chinese mother races were different in the practical and the hatching ratio between the specific gravity of eggs. On the contrary in case of Japanese mother races were no difference for the hatching ratio but difference in the practical hatching ratio between the specific gravity of eggs. 4. On the egg production company, in case of the specific gravity of medium and light eggs, the hatching and the practical hatching ratio were high significance, but no difference in the specific gravity of heavy eggs.

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Efficiency of Superconducting Gravimeter Observations and Future Prospects

  • Neumeyer Juergen
    • Korean Journal of Remote Sensing
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    • v.21 no.1
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    • pp.15-29
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    • 2005
  • Superconducting Gravimeters (SG) are the most sensitive instruments for measuring temporal gravity variations. The gravimeter is an integrating sensor therefore the gravity variations caused by different sources must be separated for studying a special effect by applying different models and data analysis methods. The present reduction methods for gravity variations induced by atmosphere and hydrosphere including the ocean and the detection and determination of the most surface gravity effects are shown. Some examples demonstrate the combination of ground (SG) and space techniques especially the combination of SG with GRACE satellite derived temporal gravity variations. Resulting from the performance of the SG and the applied data analysis methods some proposals are made for future SG applications.

Effects of the amount of egg and specific gravity on the quality of sponge cake (계란 함량과 비중이 Sponge cake의 품질에 미치는 영향)

  • 황윤경;김석영
    • Korean journal of food and cookery science
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    • v.15 no.4
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    • pp.377-381
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    • 1999
  • This study was designed to observe the effect of the amount of egg and the specific gravity on the quality of sponge cake. There was a little difference of the moisture content by the specific gravity when the amount of egg was same. However, as the amount of egg was increased at the same specific gravity, the moisture content and baking loss was significantly increased(p<0.05). At 100% of egg amount, the largest specific loaf volume was gained at 0.55 of specific gravity, in the same way 150% at 0.45, 200% at 0.35, 250% at 0.45, The hardness of sponge cake was increased as the specific gravity was increased at the same amount of egg(p<0.05). The specific gravity which the lowest hardness was gained was 0.55 with 100% of the amount of egg, in th same way 0.45 with 150%, 0.35 with 200%. As the period of storage was longer, the increase of hardness was increased as the specific gravity went up at the same amount of egg(p<0.05). Therefore, in the case of sugar content 166%, the specific gravity with maximum specific loaf volume and minimum hardness was gained 0.55 at the amount of egg 100%, 0.45 at 150%, 0.35 at 200% and 0.35 at 250%.

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A Study on the Generation of Capillary Waves on Steep Gravity Waves

  • Lee, Seung-Joon
    • Journal of Ship and Ocean Technology
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    • v.4 no.4
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    • pp.45-55
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    • 2000
  • A formal solution method using the complex analysis is given for the problems derived by Longuet-Higgins(1963). The same method is applied to a new perturbation problem of higher approximation. Interpretation of its solution made it possible to confirm that the rough agree-ment of Longuet-Higgins\`s prediction with experimental data of Cox(1958) was mainly due to the fact that the gravity effect in the perturbation problem was neglected for the case when the basic gravity wave not sufficiently steep.

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An Analysis of DEM and Gravity Effect for Precision Geoid Determination in Korea (우리나라 정밀지오이드 구축을 위한 지형자료 및 중력자료 영향 분석)

  • Lee, Bo-Mi;Lee, Ji-Sun;Kwon, Jay-Hyoun;Lee, Yong-Wook
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.26 no.5
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    • pp.519-527
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    • 2008
  • The basic elements in precise geoid determination are the gravity and topographic data with reliable quality and distribution. In this study, the effect of the gravity and topographic data on the precision of the geoid are analyzed through simulations in which the quality and distribution of the data are artificially controlled. It was found that the distribution of the topographic data has more effect on the precision of geoid than the quality of the it. This leads to the conclusion that the SRTM (Shuttle Radar Topography Mission) DTM (Digital Terrain Model) with resolution of 90m is qualified as a topographic data in geoid determination. In the experiments with gravity data, on the other hand, the aliasing effect caused by the low data density caused large errors in geoid. It was found that the more gravity data especially in north-eastern mountainous area is needed for precise geoid determination in Korea.