• Title/Summary/Keyword: Ratios

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Reflection of plane waves from the boundary of a thermo-magneto-electroelastic solid half space

  • Singh, Baljeet;Singh, Aarti
    • Coupled systems mechanics
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    • v.10 no.2
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    • pp.143-159
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    • 2021
  • The theory of generalized thermo-magneto-electroelasticity is employed to obtain the plane wave solutions in an unbounded, homogeneous and transversely isotropic medium. Reflection phenomena of plane waves is considered at a stress free and thermally insulated surface. For incidence of a plane wave, the expressions of reflection coefficients and energy ratios for reflected waves are derived. To explore the characteristics of reflection coefficients and energy ratios, a quantitative example is set up. The half-space of the thermo-magneto-electroelastic medium is assumed to be made out of lithium niobate. The dependence of reflection coefficients and energy ratios on the angle of incidence is illustrated graphically for different values of electric, magnetic and thermal parameters.

Statistical analysis of the influences of admixtures and elevated temperatures on mortar properties

  • Topcu, Ilker Bekir;Unverdi, Aytac;Yildirim, Vural
    • Computers and Concrete
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    • v.29 no.3
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    • pp.169-186
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    • 2022
  • Mortar is produced with different degrees of temperature and ratios of admixture materials. In order to produce strength mortar, the degree of temperature and the ratio of admixture materials must be optimized. This paper examines experimental effects by applying certain degrees of temperature and ratios of admixture materials to statistically understand the changes in the strength of mortar. The Taguchi method is used for the above-mentioned optimization problem. Firstly, factorial ANOVA is used to investigate the difference of means between the experiments. Due to the significant differences in obtained means, the regression analysis is applied. On the other hand, the effects of the varying degrees of temperature and admixture ratios are presented via 3D plots. Finally, the statistical results of ANOVA and Taguchi indicate that degree of temperature and the different ratios of admixture materials can affect the behaviour of mortar under the tests.

Validity assessment of aspect ratios based on Timoshenko-beam model: Structural design

  • Emad Ghandourah;Muzamal Hussain;Mohamed A. Khadimallah;Mashhour Alazwari;Mohamed R. Ali;Mohammed A. Hefni
    • Computers and Concrete
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    • v.31 no.1
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    • pp.1-7
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    • 2023
  • In this paper, Timoshenko-beam model is developed for the vibration of double carbon nanotubes. The resulting frequencies are gained for axial wave mode and length-to-diameter ratios. The natural frequency becomes more prominent for lower length-to-diameter ratios and diminished for higher ratios. The converse behavior is observed for axial wave mode with clamped-clamped and clamped-free boundary conditions. The frequencies of clamped-free are lower than that of clamped-clamped boundary condition. The eigen solution is obtained to extract the frequencies of double walled carbon nanotubes using Galerkin's method through axial deformation function. Computer softer MATLAB is used for formation of frequency values. The frequency data is compared with available literature and found to be in agreement.

Plane harmonic waves in fractional orthotropic magneto-thermoelastic solid with rotation and two-temperature

  • Himanshi;Parveen Lata
    • Coupled systems mechanics
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    • v.12 no.2
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    • pp.103-125
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    • 2023
  • The present research is focused on the study of plane harmonic waves in a two-dimensional orthotropic magneto-thermoelastic media with fractional order theory of generalized thermoelasticity in the light of two-temperature and rotation due to time harmonic sources. Here, we studied three types of waves namely quasi-longitudinal (QL), quasi-transverse (QTS) and quasi thermal (QT) waves. The variations in the wave properties such as phase velocity, attenuation coefficient and specific loss have been noticed with respect to frequency for the reflected waves. Further the value of amplitude ratios, energy ratios and penetration depth are computed numerically with respect to angle of incidence. The numerical simulated results are presented graphically to show the effect of fractional parameter based on its conductivity (0<α<1 for weak, α=1 for normal, 1<α≤2 for strong conductivity) on all the components.

Hysteretic Characteristics and Deformation Modes of Steel Plate Shear Walls According to Aspect Ratios and Width-to-Thickness Ratios (강판 형상비 및 판폭두께비에 따른 강판전단벽의 변형모드 및 이력특성)

  • Shin, Dong-Hyeon
    • Journal of Korean Association for Spatial Structures
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    • v.24 no.1
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    • pp.37-45
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    • 2024
  • Steel plate shear walls (SPSWs) have been recognized as an effective seismic-force resisting systems due to their excellent strength and stiffness characteristics. The infill steel plate in a SPSW is constrained by a boundary frame consisting of vertical and horizontal structural members. The main purpose of this study was to investigate deformation modes and hysteretic characteristics of steel plate shear walls (SPSWs) to consider the effects of their aspect ratios and width-to-thicness ratios. The finite element model (FEM) was establish in order to simulate cyclic responses of SPSWs which have the two-side clamped boundary condition and made of conventional steel grade. The stress distribution obtained from the FEA results demonstrated that the principal stresses on steel plate with large thickness-to-width ratio were more uniformly distributed along its horizontal cross section due to the formation of multiple struts.

Critical Ratios of Ca/Al and Mg/Al in Nutrent Solution Limiting Growth of Pinus thunbergii (해송의 생육을 저해하는 Ca/Al 및 Mg/Al의 한계 비율)

  • Lee, Wi-Young;Yang, Jae E.;Park, Chang-Jin;Zhang, Yong-Seon;Ok, Yong-Sik
    • Korean Journal of Soil Science and Fertilizer
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    • v.37 no.5
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    • pp.329-335
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    • 2004
  • Acid deposition in forest adjacent to the industrial complexes causes soil acidification resulting in the leaching of cations, decreases of buffering capacity and increases of toxic metal concentrations such as Al, Fe, Mn and Cu in soil solution. Changes of nutrient availability equilibria by acid deposition have been known to retard the growth of pine trees. Objective of this research was to assess the critical ratios of Ca/Al and Mg/Al limiting the growth of Pinus thunbergii in the hydroponic culture. The Ca concentration and Ca/Al ratio in stalks of pine tree were increased as increasing Ca/Al molar ratio in the nutrient solution, but were not changed when the Ca/Al molar ratio was adjusted to greater than 1. Growth of Pinus thunbergii was inhibited at the Ca/Al molar ratio lower than l due to the Ca deficiency. The molar ratios of Ca/Al in the needles of Pinus thunbergii showed the similar tendency with the stalks. This indicated that Ca/Al molar ratio of 1 in the growth media was the critical level limiting the growth of Pinus thunbergii. Concentration of Mg and Mg/Al molar ratios in the stalks of pine tree were increased as increasing Mg/Al molar ratio in nutrient solution. Molar ratios of Mg/Al in the needles were increased as increasing Mg/Al ratios in nutrient solution up to 0.83, which was the critical level limiting the growth of Pinus thunbergii.

A Study on the Mechanism of Urinary and Biliary Excretion of Chloramphenicol in the Dog (개에 있어서 Chloramphenicol의 뇨(尿) 및 담즙중(膽汁中) 배설기전(排泄機轉)에 관(關)한 연구(硏究))

  • Kim, Sung-Won
    • Journal of Pharmaceutical Investigation
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    • v.7 no.1_4
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    • pp.38-50
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    • 1977
  • A study on the mechanism of biliary and urinary excretion of chloramphenicol has been performed in the dog. 1) Chloramphenicol administered intravenously to dogs with ligated renal pedicle, readily appeared in bile greater than in plasma. 6.9% of a 50mg /kg i. v. dose of chloramphenicol were excreted into bile within 100 minutes. During the same periods of above experiment, the bile/plasma concentration ratios(B/P ratios) were 46 to 87. 2) Chloramphenicol injected into the vein of dog was rapidly excreted into urine. 18% of the administered dose were excreted into urine within 70 minutes. In the same periods of this experiment, Ccm/Ccr ratios were greater than 1.0 in most cases. 3) In experiment of simultaneous measurement of biliary and urinary excretion of chloramphenicol, Ccm/Ccr ratios were less than 1.0 and B/P ratios were 50 to 52. 4) In experiment measured simultaneously biliary and urinary excretion both Ccm/Ccr and $C^Hcm$(hepatic clearance) were significantly declined by probenecid, but not affected by 2,4-DNP and aminophylline although 2,4-DNP increased only bile flow and aminophylline both bile and urine volume. 5) Ccm/Ccr and $C^Hcm$ were increased in proportion to increment of plasma concentration ranging from 3.3 to 30 mg% of chloramphenicol. But when plasma concentration were increased to 70mg %, Ccm/Ccr were not increased and $C_Hcm$ were reduced about 30% in comparison with values obtajned at 30mg% of chloramphenicol. 6) Free/Bound(free to bouid from) ratios ranging from 1.0 to 90.0mg% of chloramphenicol were 76.2+3.72% $(mean{\pm}S.E.)$ Above results suggest that chloramphenicol is excreted into bile by a process of active trasport, that excretion of chloramphenicol into urine was made up with dual process, reabsorption and secretion, and that renal secretion was attained by active trasport process although renal reabsorption process could not understand.

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Age Estimation by Radiological Measuring Pulp Chamber of Mandibular First Molar in Korean Adults

  • Jeon, Hye-Mi;Kim, Jin-Hwa;Heo, Jun-Young;Ok, Soo-Min;Jeong, Sung-Hee;Ahn, Yong-Woo
    • Journal of Oral Medicine and Pain
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    • v.40 no.4
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    • pp.146-154
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    • 2015
  • Purpose: The purpose of present study was to develop a method for assessing the chronological age of Korean adults based on the relationship between age and size of pulp cavity using dental radiographs of mandibular first molars. Methods: A total of 325 dental radiographs of Korean adults with known age and gender were selected for the study (199 males and 126 females) which were taken in the period between January 2009 and June 2014 at the Pusan National University Dental Hospital. The measurements were carried out on both orthopantomographs (OPGs) and intraoral periapical radiographs of mandibular first molar and the following ratios were calculated: pulp chamber floor height ratio (F/L), pulp chamber ceiling height ratio (R/L), and pulp chamber depth ratio (D/L). Results: The ratios of measurements on intraoral periapical images of mandible first molar generally produce more reliable data than the measurements on OPGs. The pulp chamber floor height ratio and pulp chamber thickness ratio showed significant correlation with age, whereas the pulp chamber ceiling height ratios showed weak correlation with age. It was found that the best correlations between the ratios and age were found for pulp chamber thickness ratios (r=-0.731 to -0.751). The multiple regression models were derived using 3 ratios that were significantly correlated with age. The determination coefficients ($R^2$) of the models ranged from 0.556 to 0.596. Conclusions: Our results indicate that the pulp chamber thickness and pulp chamber floor height in mandibular first molar are an age-dependent variable in adults which can be used to estimate age with reasonable accuracy. The higher image quality of dental radiographs will probably narrow the age estimation error and improve dental age estimation.

Hospital Financial Performances and Separation of Dispensary from Medical Practice (의약분업 전후 병원 재무성과의 변화)

  • Jung, Kyu-Eon;Ju, Jeong-Bun;Kim, Young-Kyu
    • Korea Journal of Hospital Management
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    • v.9 no.3
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    • pp.49-70
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    • 2004
  • This study analyzes the effect of separation of dispensary from medical practice on hospital management performance. The results are as follow. The earning ratios of large size hospitals become deteriorated significantly after the separation of dispensary. The growth ratios of revenues from inpatient were unchanged, but the growth ratios of revenues from outpatient of large and middle size hospitals were decreased significantly. Hospitals can't sell the medicines to the outpatient after the separation of dispensary, but they can do to the outpatient. The labor cost ratios of small and large size hospitals are increased significantly after the separation of dispensary. There are two reasons for increase of labor cost ratios. One is the decrease of material cost ratio. The other is the increase of doctor's salary. The material cost ratios of every size hospital are decreased significantly after the separation of dispensary. Because medicines costs of outpatients are decreased. The labor cost and doctors' salary per patient of middle and large size hospitals are increased significantly after the separation of dispensary. And average treatment fees per day of inpatients of middle and large size hospitals are increased significantly after the separation of dispensary. But those of outpatients are decreased significantly. Average numbers of outpatients per bed of small and large hospitals are decreased significantly after the separation of dispensary. And average numbers of inpatients per bed of large hospitals are decreased significantly. In summary, as a consequence of separation of dispensary from medical practice, management performances of large size hospitals become deteriorated significantly.

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Effect of Dietary Structural to Nonstructural Carbohydrate Ratio on Rumen Degradability and Digestibility of Fiber Fractions of Wheat Straw in Sheep

  • Tan, Z.-L.;Lu, D.-X.;Hu, M.;Niu, W.-Y.;Han, C.-Y.;Ren, X.-P.;Na, R.;Lin, S.-L.
    • Asian-Australasian Journal of Animal Sciences
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    • v.15 no.11
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    • pp.1591-1598
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    • 2002
  • The effect of different dietary structural carbohydrate (SC) to nonstructural carbohydrate (NSC) ratios on fiber degradation, digestion, flow, apparent digestibility and rumen fluid characteristics was studied with a design using 18 wethers fitted with permanent rumen and duodenum cannulae. All sheep were divided into six groups randomly, receiving six diets with varying SC to NSC ratios. All diets contained the same proportion of wheat straw and concentrate. The dietary SC to NSC ratios were adjusted by adding cornstarch to the concentrate supplements. The duodenal and fecal flows of dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose (HC) and cellulose (CEL) were estimated using chromium-mordanted wheat straw as a flow marker. The degradation parameters of wheat straw DM, NDF, ADF, HC and CEL were determined by incubating the ground wheat straw in nylon bags in the rumen for different periods of time. There was no effect (p>0.05) of the different dietary SC to NSC ratios on rumen pH or $NH_3$-N, but acetate, propionate and butyrate concentrations were significantly affected (p<0.05 or p<0.01) by dietary SC to NSC ratios in the rumen fluid. When the dietary SC to NSC ratio was 2.86, the highest rumen degradability of wheat straw DM, NDF, ADF and CEL was found, but the highest apparent rumen digestibilities of DM, NDF, ADF, HC and CEL occurred at a 2.64 SC to NSC ratio. However, because of compensatory digestion in the hindgut, the apparent digestibilities of DM, NDF, ADF, HC and CEL were highest when the dietary SC to NSC ratio was 2.40. In conclusion, there is a optimal range of dietary SC to NSC ratios (between 2.86 and 2.40) that is beneficial to maximize wheat straw fiber degradation and apparent digestibility.