• Title/Summary/Keyword: energy-balance

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Energy-factor-based damage-control evaluation of steel MRF systems with fuses

  • Ke, Ke;Yam, Michael C.H.
    • Steel and Composite Structures
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    • v.22 no.3
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    • pp.589-611
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    • 2016
  • The primary objectives of this research are to investigate the energy factor response of steel moment resisting frame (MRF) systems equipped with fuses subject to ground motions and to develop an energy-based evaluation approach for evaluating the damage-control behavior of the system. First, the energy factor of steel MRF systems with fuses below the resilience threshold is derived utilizing the energy balance equation considering bilinear oscillators with significant post-yielding stiffness ratio, and the effect of structural nonlinearity on the energy factor is investigated by conducting a parametric study covering a wide range of parameters. A practical transformation approach is also proposed to associate the energy factor of steel MRF systems with fuses with classic design spectra based on elasto-plastic systems. Then, the energy balance is extended to structural systems, and an energy-based procedure for damage-control evaluation is proposed and a damage-control index is also derived. The approach is then applied to two types of steel MRF systems with fuses to explore the applicability for quantifying the damage-control behavior. The rationality of the proposed approach and the accuracy for identifying the damage-control behavior are demonstrated by nonlinear static analyses and incremental dynamic analyses utilizing prototype structures.

Modified DEBA for determining size dependent shear fracture energy of laminates

  • Goodarzi, M. Saeed;Hosseini-Toudeshky, Hossein
    • Steel and Composite Structures
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    • v.28 no.1
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    • pp.111-121
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    • 2018
  • It has been argued that fracture energy of composite laminates depends on their thickness and number of layers. In this paper a modified direct energy balance approach (DEBA) has been developed to evaluate the mode-II shear fracture energy for E-glass/Epoxy laminates from finite element model at an arbitrary thickness. This approach considers friction and damage/plasticity deformations using cohesive zone modeling (CZM) and nonlinear finite element modeling. The presence of compressive stress and resulting friction was argued to be a possible cause for the thickness dependency of fracture energy. In the finite element modeling, CZM formulation has been developed with bilinear cohesive constitutive law combined with friction consideration. Also ply element have been developed with shear plastic damage model. Modified direct energy balance approach has been proposed for estimation of mode-II shear fracture energy. Experiments were performed on laminates of glass epoxy specimens for characterization of material parameters and determination of mode-II fracture energies for different thicknesses. Effect of laminate thickness on fracture energy of transverse crack tension (TCT) and end notched flexure (ENF) specimens has been numerically studied and comparison with experimental results has been made. It is shown that the developed numerical approach is capable of estimating increase in fracture energy due to size effect.

Effects of Muscle Energy Technique on Knee Extensor Muscle Strength, Knee Range of Motion, Balance, and Walking Ability in Elderly Women during the Chronic Phase after Total Knee Replacement (슬관절 전치환술 후 만성기 여성 노인의 슬관절 신전근에 근에너지기법이 근력, 관절가동범위, 균형, 보행능력에 미치는 영향)

  • Song, Hyoung-bong;Park, Gun-hong
    • The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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    • v.27 no.2
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    • pp.55-67
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    • 2021
  • Background: This study aimed to use the muscle energy technique (MET) with total knee replacement (TKR) during the chronic phase in a clinical setting and confirm its effects on the knee extensor strength and ROM, balance, and walking ability. Methods: A total of 20 female patients who underwent TKR 1~4 years ago were assigned to two groups (Control: Q setting exercise+general physical therapy, n=10; Exp: MET+general physical therapy, n=10). Interventions were performed three times a week for 4 weeks. The strength of the knee extensor was evaluated using an aneroid sphygmomanometer, and ROM was evaluated using degrees at the end range on active knee flexion. The main balance outcomes were evaluated using two standard scale (TSS) and timed up and go (TUG) test, whereas the walking ability was evaluated using the 10 meter walk test (10MWT). Results: Analysis showed that both groups had significant increases in strength, ROM, TSS, TUG, and 10MWT. Differences in all variables were significant between the control and Exp groups at the post-intervention evaluation (p<.05). However, no significant difference was observed in strength and TUG. Conclusion: Results of this study demonstrated that MET would help improve the strength, ROM, balance, and walking ability of patients with chronic TKR who want to enhance their abilities and performance in activities of daily living.

Comparison of the Effects of Applying Muscle Energy Techniques Versus Stretching Techniques to the Ankle Joint on Ankle Joint Range of Motion, Balance Ability and Gait Ability of Chronic Stroke Patients with Limited Ankle Dorsiflexion (근에너지 기법과 스트레칭 기법의 발목관절 적용이 발등굽힘 제한이 있는 만성 뇌졸중 환자의 발목 관절가동범위, 균형 능력, 보행 능력에 미치는 영향 비교)

  • Tae-hyeon Heo;Suhn-yeop Kim
    • Journal of the Korean Society of Physical Medicine
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    • v.19 no.1
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    • pp.69-79
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    • 2024
  • PURPOSE: This study compared the effect of the muscle energy technique (MET) and stretching technique on ankle dorsiflexion passive range of motion, balance, and gait ability of stroke patients with limited ankle dorsiflexion. METHODS: Forty-four post-stroke patients participated. The participants were randomized into the MET group (METG; n = 22) and the stretching group (STG; n = 22). The METG was subjected to the MET to relax the dorsiflexion, while the STG was subjected to the dorsiflexion stretching technique. Both groups completed standard neurological physical therapy for 30 min per session. The intervention was conducted five times a week over 3 weeks for a total of 15 times. All participants underwent ankle dorsiflexion passive range of motion measurement and Berg Balance Scale score determination and completed a 10-m walking test and the timed up and go test before and after the intervention. RESULTS: After the 3-week intervention, both groups showed significant improvement after the intervention (p < .05). METG participants showed greater improvements in ankle dorsiflexion passive range of motion and 10-m walking test results compared to STG participants (p < .05). CONCLUSION: Both interventions improved ankle dorsiflexion passive range of motion, balance, and gait ability in stroke patients with limited ankle dorsiflexion. Moreover, the MET was superior to ankle dorsiflexion passive range of motion on the 10-m walking test.

Effect of Sources of Supplementary Protein on Intake, Digestion and Efficiency of Energy Utilization in Buffaloes Fed Wheat Straw Based Diets

  • Mehra, U.R.;Khan, M.Y.;Lal, Murari;Hasan, Q.Z.;Das, Asit;Bhar, R.;Verma, A.K.;Dass, R.S.;Singh, P.
    • Asian-Australasian Journal of Animal Sciences
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    • v.19 no.5
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    • pp.638-644
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    • 2006
  • Sixteen adult male buffaloes (average body weight $443{\pm}14kg$) were equally distributed into four groups in an experiment to study the effect of supplementary protein sources on energy utilization efficiency in buffaloes fed a wheat straw-based diet. The animals in the control group were offered a basal diet composed of 700 g deoiled ground nut cake and ad libitum wheat straw. Animals of other groups were offered 1.8 kg of soyabean meal (SBM), linseed meal (LSM) or mustard cake (MC) along with the basal diet. Protein supplementation increased the digestibility of DM (p<0.01), OM (p<0.01) CP (p<0.01) and CF (p<0.05). Maximum CP digestibility was observed on SBM, followed by LSM and MC when compared to the control. Total DMI and DOMI was significantly (p<0.01) higher in protein supplemented groups with no differences between treatment groups. Digestible crude protein (DCP) intake and N balance were significantly (p<0.01) different between the groups; maximum response was obtained with SBM supplementation, followed by LSM and MC. Faecal energy was significantly (p<0.01) lower in SBM and LSM groups in comparison to other groups. Methane production (% DEI) was significantly (p<0.05) lower on the SBM treatment. Metabolizable energy (ME) intake increased significantly due to protein supplementation. Metabolizable energy intake (MEI) of animals in the MC group was less than LSM and SBM. Energy balance was increased significantly (p<0.01) due to protein supplementation and within supplement variation was also significant with maximum balance in SBM followed by LSM and MC groups. Protein supplementation significantly (p<0.05) increased the digestibility and metabolizability of energy from whole ration. Metabolizable energy (ME) content (Mcal/kg DM) of SBM, LSM and MC was 4.49, 3.56 and 2.56, respectively. It was concluded that protein supplementation of wheat straw increased intake, digestibility and metabolizability of energy and maximum response could be obtained when soybean meal was used as a supplement.

Effect of Level of Leucaena leucocephala in the Diets of Jamunapari Goats on carbon Nitrogen and Energy Balances

  • Haque, N.;Khan, M.Y.;Murarilal, Murarilal
    • Asian-Australasian Journal of Animal Sciences
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    • v.10 no.5
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    • pp.455-459
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    • 1997
  • Fifteen intact male Jamunapari goats, average body weight $22.0{\pm}1.18kg$ were divided into three groups of 5 animals in each to investigate the effects of feeding leucaena on energy retention and distribution of retained energy. Leucaena leaves and twigs provided 0%, 25% and 50% of CP in the rations of animals in $L_1$ (control), $L_2$ and $L_3$ groups, respectively. Energy balances were determined in an open circuit respiration chamber from gaseous exchange and nitrogen carbon balances. Energy retentions calculated from gaseous exchange data were 181.6, 190.0 and 172.8 kJ/kg $W^{0.75}/d$ and from carbon-nitrogen balances were 178.2, 199.5 and 171.1 kJ/kg $W^{0.75}/d$ in $L_1$, $L_2$ and $L_3$ groups, respectively. No significant difference was observed among the groups in both the methods. The retention of nitrogen and energy in the form of protein was similar in different treatment groups. Similarly, no significant effect was observed on energy retention in the form of fat and total energy retention due to incorporation of leucaena in the diets.

Numerical hydrodynamic analysis of an offshore stationary-floating oscillating water column-wave energy converter using CFD

  • Elhanafi, Ahmed;Fleming, Alan;Macfarlane, Gregor;Leong, Zhi
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.9 no.1
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    • pp.77-99
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    • 2017
  • Offshore oscillating water columns (OWC) represent one of the most promising forms of wave energy converters. The hydrodynamic performance of such converters heavily depends on their interactions with ocean waves; therefore, understanding these interactions is essential. In this paper, a fully nonlinear 2D computational fluid dynamics (CFD) model based on RANS equations and VOF surface capturing scheme is implemented to carry out wave energy balance analyses for an offshore OWC. The numerical model is well validated against published physical measurements including; chamber differential air pressure, chamber water level oscillation and vertical velocity, overall wave energy extraction efficiency, reflected and transmitted waves, velocity and vorticity fields (PIV measurements). Following the successful validation work, an extensive campaign of numerical tests is performed to quantify the relevance of three design parameters, namely incoming wavelength, wave height and turbine damping to the device hydrodynamic performance and wave energy conversion process. All of the three investigated parameters show important effects on the wave-pneumatic energy conversion chain. In addition, the flow field around the chamber's front wall indicates areas of energy losses by stronger vortices generation than the rear wall.

Dynamic Energy Balance and Obesity Prevention

  • Yoo, Sunmi
    • Journal of Obesity & Metabolic Syndrome
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    • v.27 no.4
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    • pp.203-212
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    • 2018
  • Dynamic energy balance can give clinicians important answers for why obesity is so resistant to control. When food intake is reduced for weight control, all components of energy expenditure change, including metabolic rate at rest (resting energy expenditure [REE]), metabolic rate of exercise, and adaptive thermogenesis. This means that a change in energy intake influences energy expenditure in a dynamic way. Mechanisms associated with reduction of total energy expenditure following weight loss are likely to be related to decreased body mass and enhanced metabolic efficiency. Reducing calorie intake results in a decrease in body weight, initially with a marked reduction in fat free mass and a decrease in REE, and this change is maintained for several years in a reduced state. Metabolic adaptation, which is not explained by changes in body composition, lasts for more than several years. These are powerful physiological adaptations that induce weight regain. To avoid a typically observed weight-loss and regain trajectory, realistic weight loss goals should be established and maintained for more than 1 year. Using a mathematical model can help clinicians formulate advice about diet control. It is important to emphasize steady efforts for several years to maintain reduced weight over efforts to lose weight. Because obesity is difficult to reverse, clinicians must prioritize obesity prevention. Obesity prevention strategies should have high feasibility, broad population reach, and relatively low cost, especially for young children who have the smallest energy gaps to change.

Genetic parameter estimation for milk β-hydroxybutyrate and acetone in early lactation and its association with fat to protein ratio and energy balance in Korean Holstein cattle

  • Ranaraja, Umanthi;Cho, KwangHyun;Park, MiNa;Kim, SiDong;Lee, SeokHyun;Do, ChangHee
    • Asian-Australasian Journal of Animal Sciences
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    • v.31 no.6
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    • pp.798-803
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    • 2018
  • Objective: The objective of this study was to estimate the genetic parameters for milk ${\beta}$-hydroxybutyrate (BHBA), acetone (Ac), fat protein ratio (FPR), and energy balance (EB) using milk test day records and investigate the effect of early lactation FPR and EB on milk ketone body concentrations. Methods: Total 262,940 test-day records collected from Korea Animal Improvement Association during the period of 2012 to 2016 were used in this study. BHBA and Ac concentrations in milk were measured by Fourier transform infrared spectroscopy (FTIR). FPR values were obtained using test day records of fat and protein percentage. EB was calculated using previously developed equation based on parity, lactation week, and milk composition data. Genetic parameters were estimated by restricted maximum likelihood procedure based on repeatability model using Wombat program. Results: Elevated milk BHBA and Ac concentrations were observed during the early lactation under the negative energy balance. Milk FPR tends to decrease with the decreasing ketone body concentrations. Heritability estimates for milk BHBA, Ac, EB, and FPR ranged from 0.09 to 0.14, 0.23 to 0.31, 0.19 to 0.52, and 0.16 to 0.42 respectively at parity 1, 2, 3, and 4. The overall heritability for BHBA, Ac, EB and FPR were 0.29, 0.32, 0.58, and 0.38 respectively. A common pattern was observed in heritability of EB and FPR along with parities. Conclusion: FPR and EB can be suggested as potential predictors for risk of hyperketonemia. The heritability estimates of milk BHBA, Ac, EB, and FPR indicate that the selective breeding may contribute to maintaining the milk ketone bodies at optimum level during early lactation.

Implementation of a Power Simulator for Energy Balance Analysis of a LEO Satellite (저궤도 위성의 에너지 균형 분석을 위한 전력 시뮬레이터의 구현)

  • Jeon, Moon-Jin;Lee, Na-Young;Kim, Day-Young;Kim, Gyu-Sun
    • Aerospace Engineering and Technology
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    • v.9 no.2
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    • pp.176-184
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    • 2010
  • The power simulator for a LEO satellite is a useful tool to analyze mission validity and energy balance for various mission scenarios by estimating power generation, power consumption, depth of discharge, bus voltage, charging/discharging current, etc. In this paper, it is described the calculation algorithm of the solar array (SA) power, the satellite load power and the battery modeling method to develop a satellite power simulation. To simulate the SA power generation, three different operation modes (DET, MPPT, CV) of SAR (Solar Array Regulator) are considered with a SA model. The satellite load power is estimated using the satellite unit power database, the unit on/off configuration at some satellite operation modes. The bus voltage and battery charging/discharging current at the specific DoD (Depth of Discharge) are calculated based on the battery characteristics. By this satellite power simulator, it can be conveniently analyzed the energy balance and the validity of a planned mission of a LEO satellite.