• Title, Summary, Keyword: Energy transfer

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Dynamics of Resonant Energy Transfer in OH Vibrations of Liquid Water

  • Yang, Mi-No
    • Bulletin of the Korean Chemical Society
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    • v.33 no.3
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    • pp.885-892
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    • 2012
  • Energy transfer dynamics of excited vibrational energy of OH stretching bonds in liquid water is theoretically studied. With time-dependent vibrational Hamiltonian obtained from a mixed quantum/classical calculation, we construct a master equation describing the energy transfer dynamics. Survival probability predicted by the master equation is compared with numerically exact one and we found that incoherent picture of energy transfer is reasonably valid for long-time population dynamics. Within the incoherent picture, we assess the validity of independent pair approximation (IPA) often introduced in the theoretical models utilized in the analysis of experimental data. Our results support that the IPA is almost perfectly valid as applied for the vibrational energy transfer in liquid water. However, proper incorporation of radial and orientational correlations between two OH bonds is found to be critical for a theory to be quantitatively valid. Consequently, it is suggested that the Forster model should be generalized by including the effects of the pair correlations in order to be applied for vibrational energy transfer in liquid water.

A Robot System Maintained with Renewable Energy

  • Kim, Jaehyun;Moon, Chanwoo
    • International journal of advanced smart convergence
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    • v.8 no.1
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    • pp.98-105
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    • 2019
  • Energy autonomy is a system that is sustained by energy from an independent and distributed source such as renewable energy. In this paper, we propose a robotic energy autonomy in which a robot obtains energy from a renewable energy source with a limited storage capacity. As an energy transfer method, wireless power transfer is used to solve the problem of the conventional contact charging method, mechanical complexity, and to obtain high energy transfer efficiency, the image information is used to align the transmitting and receiving coils accurately. A small scale thermoelectric energy source with boost converter, battery charger, and wireless power transfer coil is constructed and an actual charging experiment is conducted to verify the proposed autonomy system.

A Study on the Application Method in Korea of Energy Harvesting Technology - Focused on the Case Study of Interseasonal Heat Transfer System - (에너지 하베스팅 기술의 국내 건축물 적용 방안에 관한 기초 연구 - Interseasonal Heat Transfer System 적용 사례 중심으로 -)

  • Jo, Byungwan;Lee, Yunsung;Yoon, Kwangwon;Kim, Dogeun
    • International Journal of Highway Engineering
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    • v.16 no.4
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    • pp.51-62
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    • 2014
  • PURPOSES: This research is a basic study for application method in korea of energy harvesting technology, and it is a research to find out the direction of architectural planning through analyzing cases of interseasonal heat transfer system applied buildings. METHODS : In this paper authors investigate application necessity of energy harvesting technology, we analyzed energy use status of building section through analyzing domestic energy consumption status and analyzed domestic renewable energy generation potential. Also we study the features of energy harvesting technology, interseasonal heat transfer system, and case study on interseasonal heat transfer system applied buildings. RESULTS : On the basis of case study on interseasonal heat transfer system applied buildings, we analyzed feasibility study and classified into four sections(economic, environment, design, applicability), and suggested directions of architectural planning. CONCLUSIONS: Economic renewable energy for public and commercial buildings(hospitals, offices, schools, factories) can be provided effectively using Interseasonal Heat Transfer.

Enhanced Switching Pattern to Improve Energy Transfer Efficiency of Active Cell Balancing Circuits Using Multi-winding Transformer (다중권선 변압기를 이용한 능동형 셀 밸런싱 회로의 에너지 전달 효율을 높이기 위한 향상된 스위칭 패턴)

  • Lee, Sang-Jung;Kim, Myoungho;Baek, Ju-Won;Jung, Jee-Hoon
    • The Transactions of the Korean Institute of Power Electronics
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    • v.24 no.4
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    • pp.279-285
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    • 2019
  • This study proposes an enhanced switching pattern that can improve energy transfer efficiency in an active cell-balancing circuit using a multiwinding transformer. This balancing circuit performs cell balancing by transferring energy stored in a specific cell with high energy to another cell containing low energy through a multiwinding transformer. The circuit operates in flyback and buck-boost modes in accordance with the energy transfer path. In the conventional flyback mode, the leakage inductance of the transformer and the stray inductance component of winding can transfer energy to an undesired path during the balancing operation. This case results in cell imbalance during the cell-balancing process, which reduces the energy transfer efficiency. An enhanced switching pattern that can effectively perform cell balancing by minimizing the amount of energy transferred to the nontarget cells due to the leakage inductance components in the flyback mode is proposed. Energy transfer efficiency and balancing speed can be significantly improved using the proposed switching pattern compared with that using the conventional switching pattern. The performance improvements are verified by experiments using a 1 W prototype cell-balancing circuit.

Energy Dissipation and Transfer among Wave Components during Directional Breaking Processes (다방향 쇄파 발생 전후의 파랑 성분간 에너지 전이 및 소산)

  • 홍기용;에스똘히오메자
    • Journal of Ocean Engineering and Technology
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    • v.17 no.6
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    • pp.1-6
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    • 2003
  • Wave energy dissipation and energy transfer between wave components, during the directional wave breakings, are investigated. Directional incipient and plunging breakers were generated by focusing the multi-frequency and multi-directional wave components at a designed location, based on a constant wave amplitude and a constant wave steepness frequency spectrum. The time series of surface wave elevation was measured at 9 different locations around the wave focusing point, using a wave gauge array. In order to examine the variation of the directional spreading function, the horizontal velocity of fluid motion was also measured. By comparing energy spectrums, before and after the breaking, the characteristics of energy dissipation and energy transfer, caused by wave breaking, are investigated. Their dependencies on directionality, as well as frequency, are analyzed. The breakings significantly dissipate wave energy, through energy transfer, in the upper region of the peak-frequency band, while enhancing wave energy in the low-frequency band.

Triplet Excitation Energy Transfer in Choleic Acid Crystals

  • Kook, Seong-Keun
    • Bulletin of the Korean Chemical Society
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    • v.28 no.12
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    • pp.2409-2413
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    • 2007
  • Time resolved phosphorescence of Dibromobenzophenone (DBBP) choleic acid crystal was observed at 4.2 K as functions of excitation energy and delay time. The experimental results reveal that the energy transfer efficiency is dependent on the excitation energy, i.e. the density of acceptors sites. As the excitation energy or delay time increases, the resonance phosphorescence does not broaden and shift gradually, rather a broad luminescence band develops about 290 cm?1 to lower energy of the resonance phosphorescence. The observation implies that energy transfer from high to low energy sites in this system is controlled by emission of phonons or vibrons. The data of time resolved experiments were analyzed in terms of a mechanism involving direct donor-acceptor excitation transport by exchange coupling. It was concluded that an isotropic twodimensional exchange interaction topology is consistent with energy transfer in this system.

Surface Energy of Graphene Transferred by Wet and Dry Transfer Methods (전사 방법에 따른 그래핀의 표면 에너지 변화)

  • Yoon, Min-Ah;Kim, Chan;Won, Sejeong;Jung, Hyun-June;Kim, Jae-Hyun;Kim, Kwang-Seop
    • Tribology and Lubricants
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    • v.35 no.1
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    • pp.9-15
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    • 2019
  • Graphene is a fascinating material for fabricating flexible and transparent devices owing to its thickness and mechanical properties. To utilize graphene as a core material for devices, the transfer process of graphene is an inevitable step. The transfer process can be classified into wet and dry methods depending on the surrounding environment. The adhesion between graphene and a target substrate determines the success or failure of the transfer process. As the surface energy of graphene is an important parameter that provides adhesion, it is useful to estimate the surface energy to understand the mechanisms of the transfer process. However, the exact surface energy of graphene is still disputed because the wetting transparency of graphene depends on the polarity of the liquid and target substrate. Previously reported results use graphene transferred by the wet method. However, there are few reports on the surface energy of graphene transferred by the dry method. In this study, the surface energy of graphene transferred by the wet and dry methods is estimated. Wetting transparency occurs for certain combinations of liquids and substrates. For graphene on a polar substrate, the surface energy decreases by 25 and 35% for the wet and dry transfer methods, respectively. However, the surface energy of graphene on dispersive substrates decreases by ~10% regardless of the transfer method. In conclusion, the surface energy of graphene is $36{\sim}38mJ/m^2$, and differs depending on the transfer method and polarity of the substrate.

Excitation Energy Transfer Rate Constants in meso-meso Linked Zn(II) Porphyrin Arrays with Energy Accepting 5,15-Bisphenylethynylated Zn(II) Porphyrin

  • Ko, Da-Mee;Kim, Hee-Young;Park, Jin-Hee;Kim, Dong-Ho;Sim, Eun-Ji
    • Bulletin of the Korean Chemical Society
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    • v.26 no.10
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    • pp.1505-1511
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    • 2005
  • The excitation energy transfer process occurring in energy donor-acceptor linked porphyrin array system is theoretically simulated using the on-the-fly filtered propagator path integral method. The compound consists of an energy donating meso-meso linked Zn(II) porphyrin array and an energy accepting 5,15-bisphenylethynylated Zn(II) porphyrin, in which the donor array and the acceptor are linked via a 1,4-phenylene spacer. Real-time path integral simulations provide time-evolution of the site population and the excitation energy transfer rate constants are determined. Simulations and experiments show an excellent agreement indicating that the path integration is a useful tool to investigate the energy transfer dynamics in molecular assemblies.

Wireless Synchronous Transfer of Power and Reverse Signals

  • Li, Yang;Li, Yumei;Feng, Shaojie;Yang, Qingxin;Dong, Weihao;Zhao, Jingtai;Xue, Ming
    • Journal of Power Electronics
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    • v.19 no.3
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    • pp.827-834
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    • 2019
  • Wireless power transfer via coupled magnetic resonances has been a hot research topic in recent years. In addition, the number of related devices has also been increasing. However, reverse signals transfer is often required in addition to wireless power transfer. The structure of the circuit for a wireless power transfer system via coupled magnetic resonances is analyzed. The advantages and disadvantages of both parallel compensation and series compensation are listed. Then the compensation characteristics of the inductor, capacitor and resistor were studied and an appropriate compensation method was selected. The reverse signals can be transferred by controlling the compensation of the resistor. In addition, it can be demodulated by extracting the change of the primary current. A 3.3 MHz resonant frequency with a 100 kHz reverse signals transfer system platform was established in the laboratory. Experimental results demonstrate that wireless power and reverse signals can be transferred synchronously.