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A triboelectric nanogenerator based on a spiral rotating shaft for efficient marine energy harvesting of the hydrostatic pressure differential
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作者 Xuemei Song Yuan Chao Pan +4 位作者 Chang Bao Han Chang Xin Liu Yaxiaer Yalikun Hui Yan Yang Yang 《Materials Reports(Energy)》 EI 2024年第3期69-76,共8页
Equipment used in underwater sensing and exploration typically relies on cables or batteries for energy supply,resulting in a limited and inconvenient energy supply and marine environmental pollution that hinder the s... Equipment used in underwater sensing and exploration typically relies on cables or batteries for energy supply,resulting in a limited and inconvenient energy supply and marine environmental pollution that hinder the sustainable development of distributed ocean sensing networks.Here,we design a deep-sea differential-pressure triboelectric nanogenerator(DP-TENG)based on a spiral shaft drive using modified polymer materials to harness the hydrostatic pressure gradient energy at varying ocean depths to power underwater equipment.The spiral shaft structure converts a single compression into multiple rotations of the TENG rotor,achieving efficient conversion of differential pressure energy.The multi-pair electrode design enables the DP-TENG to generate a peak current of 61.7μA,the instantaneous current density can reach 0.69μA cm^(-2),and the output performance can be improved by optimizing the spiral angle of the shaft.The DP-TENG can charge a 33μF capacitor to 17.5 V within five working cycles.It can also power a digital calculator and light up 116 commercial power light-emitting diodes,demonstrating excellent output capability.With its simple structure,low production cost,and small form factor,the DP-TENG can be seamlessly integrated with underwater vehicles.The results hold broad prospects for underwater blue energy harvesting and are expected to contribute to the development of self-powered equipment toward emerging“smart ocean”and blue economy applications. 展开更多
关键词 Triboelectric nanogenerators Blue energy energy harvesting Differential pressure energy Self-power sensor
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Energy conversion of rocks in process of unloading confining pressure under different unloading paths 被引量:13
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作者 赵国彦 戴兵 +1 位作者 董陇军 杨晨 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第5期1626-1632,共7页
Based on energy theory and tests of rocks with initial confining pressures of 10, 20 and 30 MPa under different unloading paths, the processes of strain energy conversion were investigated. The absorbing strain energy... Based on energy theory and tests of rocks with initial confining pressures of 10, 20 and 30 MPa under different unloading paths, the processes of strain energy conversion were investigated. The absorbing strain energy for axial compression, the dissipating strain energy for plastic deformation and cracks propagation, the expending strain energy for circumferential deformation, and the storing and releasing elastic strain energy were considered. Unloading paths included the condition of fixing axial pressure and unloading axial pressure, increasing axial pressure and unloading confining pressure, as well as unloading axial pressure and confining pressure simultaneously. Results show that expending strain energy for circumferential deformation has mainly evolved from absorbing strain energy for axial compression in three unloading paths during unloading processes. Dissipating strain energy is significantly increased only near the peak point. The effect of initial confining pressure on strain energy is significantly higher than that of unloading path. The strain energy is linearly increased with increasing initial confining pressure. The unloading path and initial confining pressure also have great influence on the energy dissipation. The conversion rate of strain energy in three paths is increased with increasing initial confining pressure, and the effect of initial confining pressure on conversion rate of strain energy is related with the unloading paths. 展开更多
关键词 unloading paths axial pressure confining pressure strain energy energy conversion
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Thermodynamic analysis and combined cycle research on recoverable pressure energy in natural gas pipeline 被引量:2
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作者 郑斌 刘俊德 《Journal of Beijing Institute of Technology》 EI CAS 2011年第1期65-70,共6页
Current research and ways of capturing mechanical energy are discussed in this paper. By the aid of the comprehensive thermodynamic analysis and Aspen simulation tool, the amount of a vailable work that can be produc... Current research and ways of capturing mechanical energy are discussed in this paper. By the aid of the comprehensive thermodynamic analysis and Aspen simulation tool, the amount of a vailable work that can be produced from capturing the pressure energy has been calculated. Based on the comprehensive thermodynamic analysis, two systems have been proposed to capture pressure energy of natural gas to generate electricity. In this study, the expression of exergy is given which can be used in evaluating purposes. A problem with this multidisciplinary study is the complicated boundary condition. In conclusion, a technical prospect on recoverable natural gas pressure energy has been presented based on total energy system theory. 展开更多
关键词 natural gas pressure energy thermodynamic analysis exergy analysis power genera-tion combined cycle total energy system
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Experimental research into the effect of gas pressure,particle size and nozzle area on initial gas-release energy during gas desorption 被引量:5
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作者 Weitao Hou Hanpeng Wang +3 位作者 Liang Yuan Wei Wang Yang Xue Zhengwei Ma 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2021年第2期253-263,共11页
Coal and gas outburst is a violent disaster driven by released energy from gas desorption.The initial expansion energy of released gas(IEERG)is a new method to predict coal and gas outburst.In this paper,an instrument... Coal and gas outburst is a violent disaster driven by released energy from gas desorption.The initial expansion energy of released gas(IEERG)is a new method to predict coal and gas outburst.In this paper,an instrument for IEERG measurement was developed.Compared with previous setups,the new one which is equipped with three convergent nozzles and quick-release mechanism gets improved in data acquisition and gas sealing and releasing performance.To comprehensively know the effect of gas pressure,particle size,and nozzle area on IEERG,a series of experiments were carried out with this new setup.The variable control test results indicated that the gas pressure-IEERG curves remain the linear trend and the particle size-IEERG curves maintain the negative exponential trend for nozzle areas at 1.13,2.26,and3.39 mm2,respectively.The increase in nozzle area leads to deceases in value of IEERG and absolute value of slope of fitting curves in each test.In addition,the orthogonal experiment showed that the influence of gas pressure,nozzle area,and particle size on IEERG decreases in turn.Only gas pressure had a marked impact on IEERG.This work offers great importance in improving the accuracy of prediction of coal and gas outburst. 展开更多
关键词 Coal and gas outburst Initial expansion energy of released gas Gas pressure Particle size Nozzle area
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Prospect of HDR geothermal energy exploitation in Yangbajing,Tibet,China,and experimental investigation of granite under high temperature and high pressure 被引量:2
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作者 Yangsheng Zhao Zijun Feng +3 位作者 Baoping Xi Jinchang Zhao Zhijun Wan Anchao Zhou 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE 2011年第3期260-269,共10页
Hot dry rock (HDR) geothermal energy, almost inexhaustible green energy, was first put forward in the 1970s. The development and testing of HDR geothermal energy are well reported in USA, Japan, UK, France and other... Hot dry rock (HDR) geothermal energy, almost inexhaustible green energy, was first put forward in the 1970s. The development and testing of HDR geothermal energy are well reported in USA, Japan, UK, France and other countries or regions. In this paper, the geological characters of Yangbajing basin were first analyzed, including the continental dynamic environments to form HDR geothermal fields in Tibet, the tectonic characteristics of south slope of Nyainqentanglha and Dangxiong-Yangbajing basin, and the in-situ stresses based on the investigations conducted, and then the site-specific mining scheme of HDR geothermal resources was proposed. For the potential development of HDR geothermal energy, a series of experiments were conducted on large-scale granite samples, 200 mm in diameter and 400 mm in length, at high temperature and high triaxial pressure for cutting fragmentation and borehole stability. For the borehole stability test, a hole of 40 mm in diameter and 400 mm in length was aforehand drilled in the prepared intact granite sample. The results indicate that the cutting velocity obviously increases with temperature when bit pressure is over a certain value, while the unit rock-breaking energy consumption decreases and the rock-breaking efficiency increases with temperature at the triaxial pressure of 100 MPa. The critical temperature and pressure that can result in intensive damage to granite are 400-500℃ and 100-125 MPa, respectively. 展开更多
关键词 hot dry rock (HDR) geothermal energy exploitation high temperature and high pressure cutting fragmentation borehole stability
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Natural frequency characteristics of thin-walled homogeneous and manifold layered cylindrical shells under pressure using energy method 被引量:2
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作者 M.R.Isvandzibaei Hishamuddin Jamaluddin Raja Ishak Raja Hamzah 《Journal of Central South University》 SCIE EI CAS 2014年第2期521-532,共12页
Energy method for the vibration of two types of cylindrical shells,namely thin-walled homogeneous isotropic and manifold layered isotropic cylindrical shells under uniform external lateral pressure is presented.The st... Energy method for the vibration of two types of cylindrical shells,namely thin-walled homogeneous isotropic and manifold layered isotropic cylindrical shells under uniform external lateral pressure is presented.The study is carried out based on strain-displacement relationship from Love's shell theory with beam functions as axial modal function.A manifold layered cylindrical shell configuration is formed by three layers of isotropic material where the inner and outer layers are stainless steel and the middle layer is aluminum.The homogeneous cylindrical shell is made-up of isotropic one layer with stainless steel.The governing equations with uniform external lateral pressure for homogeneous isotropic and manifold layered isotropic cylindrical shells are obtained using energy functional by the Lagrangian function with Rayleigh-Ritz method.The boundary conditions that are presented at the end conditions of the cylindrical shell are simply supported-simply supported,clamped-clamped and free-free.The influences of uniform external lateral pressure and symmetrical boundary conditions on the natural frequency characteristics for both homogeneous and manifold layered isotropic cylindrical shells are examined.For all boundary conditions considered,the natural frequency of both cylindrical shells with symmetric uniform lateral pressure increases as h/R ratio increases and those considering natural frequency of the both cylindrical shells with symmetric uniform lateral pressure decrease as L/R ratio increases. 展开更多
关键词 cylindrical shell manifold layered pressure energy method
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Pressure control strategy for pump motor energy transfer unit 被引量:2
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作者 Yao Jing Zhang Wei +2 位作者 Cao Xiaoming Zhao Guichun Sun Menghui 《High Technology Letters》 EI CAS 2019年第3期286-293,共8页
Multi-level pressure source system is a novel hydraulic system with distinct advantage of energy saving. In order to balance each pressure level of the multi-level pressure source system, a pump motor energy transfer ... Multi-level pressure source system is a novel hydraulic system with distinct advantage of energy saving. In order to balance each pressure level of the multi-level pressure source system, a pump motor energy transfer unit is usually equipped. However, the pump motor energy transfer has the characteristics of poor starting and low response, which cause long time of pressure adjustment and large pressure jitter when the transformer is switched to system suddenly and the motor-side pressure has pressure impact when rail of the pump-side is switched. To address these problems, this paper proposes a compound control strategy of feedforward compensation control with Fuzzy-PID to improve the controllability of the multi-level pressure source system. A test rig of the pump motor energy transfer unit is built and the controllability of compound controller and PID controller are compared. The experiment results show that, compared with the traditional PID, the adjustment time and the pressure impact are reduced by 20% and 25% with the proposed compound control strategy. Therefore, the presented compound control strategy can be used to improve starting performance and robustness of the pump motor energy transfer unit control system. 展开更多
关键词 hydraulic system pump-motor energy transfer unit pressure control energy saving
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RF energy harvesting system for wireless intraocular pressure monitoring 被引量:1
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作者 刘德盟 Mei Niansong Zhang Zhaofeng 《High Technology Letters》 EI CAS 2015年第2期212-218,共7页
This paper presents an RF energy harvesting system for wireless intraocular pressure monitoring applications.The system consists of an implantable antenna and a rectifier.A new sizing strategy is adopted to optimize t... This paper presents an RF energy harvesting system for wireless intraocular pressure monitoring applications.The system consists of an implantable antenna and a rectifier.A new sizing strategy is adopted to optimize the conversion efficiency of the rectifier,and the design principle of an implantable antenna is introduced from material selection and structure design.Results from testing demonstrate that the antenna gain is about-20 dBi and the rectifier's maximum total conversion efficiency which contains match efficiency and rectifying efficiency is 47.18%under the implementation of0.18μm standard CMOS process.The maximum power obtained from the proposed system is 8μW when the power density of electromagnetic wave is lower than the national standard 40μW/cm^2 at915 MHz,which is enough to power the intraocular pressure monitoring system. 展开更多
关键词 RF energy harvesting system implantable medical system ANTENNA RECTIFIER intraocular pressure monitoring
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Time history of seismic earth pressure response from gravity retaining wall based on energy dissipation 被引量:1
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作者 QU Hong-lue DENG Yuan-yuan +2 位作者 GAO Ya-nan HUANG Xue ZHANG Zhe 《Journal of Mountain Science》 SCIE CSCD 2022年第2期578-590,共13页
The seismic design of gravity retaining walls is based mostly on the pseudo static method.The seismic earth pressure is assumed to be a constant without considering the wave traveling effect when the seismic wave prop... The seismic design of gravity retaining walls is based mostly on the pseudo static method.The seismic earth pressure is assumed to be a constant without considering the wave traveling effect when the seismic wave propagates through the slope.However,under continuous ground motion,the actual earth pressure on the retaining wall varies with time.The present seismic earth pressure calculation method yields results that differ significantly from the actual scenario.Considering this,a slip surface curve was assumed in this study.It is more suitable for engineering practice.In addition,a theoretical calculation model based on energy dissipation was established.The time history of seismic earth pressure response under continuous ground motion was calculated using the equilibrium equation between the external power and the internal energy dissipation power of the sliding soil wedge.It can more effectively reflect the stress scenario of a retaining wall under seismic conditions.To verify the applicability of the proposed approach,a large-scale shaking table test was conducted,and the time history of the seismic earth pressure response obtained from the experiment was compared with the calculation results.The results show that the proposed approach is applicable to the calculation of the time history of seismic earth pressure response of gravity retaining walls.This lays the foundation for the seismic design of retaining structures by using dynamic time history. 展开更多
关键词 energy dissipation Time history of seismic earth pressure response Slip surface curve Gravity retaining wall Shaking table test
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Interfacial energy and match of cold pressure welded Ag/Ni and Al/Cu 被引量:3
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作者 李云涛 杜则裕 马成勇 《中国有色金属学会会刊:英文版》 CSCD 2002年第5期814-817,共4页
The technology of cold pressure welding was adopted to achieve the bonding of Al/Cu(limited soluble and forming compounds), Ag/Ni (hardly mutual soluble), and the relative state of interface was tested by HREM. The re... The technology of cold pressure welding was adopted to achieve the bonding of Al/Cu(limited soluble and forming compounds), Ag/Ni (hardly mutual soluble), and the relative state of interface was tested by HREM. The results indicate that stable interface is always corresponding to the low interfacial energy value; the stable interface is not coherent but partly-coherent because of the twisting of grain boundary caused by pressure, meanwhile existing dislocation. Namely, the interfacial match and other states under the condition of cold pressure welding are different from the situation that under the condition of thermal action. Moreover, theoretical analyses and calculation on the base of thermodynamics, crystallogeny, solid physics etc, were discussed. 展开更多
关键词 Ag/Ni AL/CU 冷压焊 界面能 匹配关系 银/镍 铝/铜
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In situ electrical resistance and activation energy of solid C_(60) under high pressure
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作者 杨洁 刘才龙 高春晓 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第9期516-519,共4页
The in situ electrical resistance and transport activation energies of solid C60 fullerene have been measured under high pressure up to 25 GPa in the temperature range of 300-423 K by using a designed diamond anvil ce... The in situ electrical resistance and transport activation energies of solid C60 fullerene have been measured under high pressure up to 25 GPa in the temperature range of 300-423 K by using a designed diamond anvil cell. In the experiment, four parts of boron-doped diamond films fabricated on one anvil were used as electrical measurement probes and a W-Ta thin film thermocouple which was integrated on the other diamond anvil was used to measure the temperature. The current results indicate that the measured high-pressure resistances are bigger than those reported before at the same pressure and there is no pressure-independent resistance increase before 8 GPa. From the temperature dependence of the resistivity, the C60 behaviors as a semiconductor and the activation energies of the cubic C60 fullerene are 0,49, 0.43, and 0.36 eV at 13, 15, and 19 GPa, respectively. 展开更多
关键词 high pressure electrical resistance activation energy C60 fullerene
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Minimum wall pressure coefficient of orifice plate energy dissipater
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作者 Wan-zheng Ai Jia-hong Wang 《Water Science and Engineering》 EI CAS CSCD 2015年第1期85-88,共4页
Orifice plate energy dissipaters have been successfully used in large-scale hydropower projects due to their simple structure, convenient construction procedure, and high energy dissipation ratio. The minimum wall pre... Orifice plate energy dissipaters have been successfully used in large-scale hydropower projects due to their simple structure, convenient construction procedure, and high energy dissipation ratio. The minimum wall pressure coefficient of an orifice plate can indirectly reflect its cavitation characteristics: the lower the minimum wall pressure coefficient is, the better the ability of the orifice plate to resist cavitation damage is. Thus, it is important to study the minimum wall pressure coefficient of the orifice plate. In this study, this coefficient and related parameters, such as the contraction ratio, defined as the ratio of the orifice plate diameter to the flood-discharging tunnel diameter; the relative thickness, defined as the ratio of the orifice plate thickness to the tunnel diameter; and the Reynolds number of the flow through the orifice plate, were theoretically analyzed, and their relationships were obtained through physical model experiments. It can be concluded that the minimum wall pressure coefficient is mainly dominated by the contraction ratio and relative thickness. The lower the contraction ratio and relative thickness are, the larger the minimum wall pressure coefficient is. The effects of the Reynolds number on the minimum wall pressure coefficient can be neglected when it is larger than 10^5. An emoirical expression was presented to calculate the minimum wall oressure coefficient in this study. 展开更多
关键词 Orifice plate Minimum wall pressure coefficient CAVITATION Contraction ratio Relative thickness energy dissipater
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Effect of gas pressure on ion energy at substrate side of Ag target radio-frequency and very-high-frequency magnetron sputtering discharge
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作者 Weichen Nl Chao YE +1 位作者 Yiqing YU Xiangying WANG 《Plasma Science and Technology》 SCIE EI CAS CSCD 2022年第2期162-171,共10页
The effect of gas pressure on ion energy distribution at the substrate side of Ag target radio-frequency(RF)and very-high-frequency(VHF)magnetron sputtering discharge was investigated.At lower pressure,the evolution o... The effect of gas pressure on ion energy distribution at the substrate side of Ag target radio-frequency(RF)and very-high-frequency(VHF)magnetron sputtering discharge was investigated.At lower pressure,the evolution of maximum ion energy(E)with discharge voltage(V)varied with the excitation frequency,due to the joint contribution of the ion generation in the bulk plasma and the ion movement across the sheath related to the ion transit sheath timeτiand RF periodτRF.At higher pressure,the evolution of E–V relationships did not vary with the excitation frequency,due to the balance between the energy lost through collisions and the energy gained by acceleration in the electric field.Therefore,for RF and VHF magnetron discharge,lower gas pressure can have a clear influence on the E–V relationship. 展开更多
关键词 excitation frequency gas pressure ion energy magnetron sputtering discharge
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Control performance and energy saving of multi-level pressure switching control system based on independent metering control
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作者 Cao Xiaoming Yao Jing +1 位作者 Sha Tong Wang Pei 《High Technology Letters》 EI CAS 2020年第2期224-234,共11页
Aiming at the problem of large energy consumption in hydraulic control system with large load and variable working conditions,based on the multi-level pressure switching control system(MPSCS),a multi-level pressure sw... Aiming at the problem of large energy consumption in hydraulic control system with large load and variable working conditions,based on the multi-level pressure switching control system(MPSCS),a multi-level pressure switching control system based on independent metering control is proposed combined with the independent metering control technology.The configuration principle of the system is given,the mathematical model of this system is established,and the control strategy of the system under 4 different working quadrants is put forward.Finally,the control performance and energy saving characteristics of the system are tested.The test results show that the switching of high and low pressure power supply has a certain effect on the response of step position and ramp position under impedance working condition.The displacement curves show slow climbing or abrupt change of ramp position,and the position accuracy is less than 1 mm.The multi-level pressure switching control system based on independent metering control can recover and store energy under the transcendence working conditions.The control accuracy is about 1 mm,and the energy recovery rate is about 70%~80%. 展开更多
关键词 MULTI-LEVEL pressure INDEPENDENT METERING CONTROL DISPLACEMENT CONTROL energy SAVING hydraulic switching system
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Pressure Gradient, Power, and Energy of Vortices
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作者 Jack Denur 《Open Journal of Fluid Dynamics》 2018年第2期216-247,共32页
We consider small vortices, such as tornadoes, dust devils, whirlpools, and small hurricanes at low latitudes, for which the Coriolis force can be neglected. Such vortices are (at least approximately) cylindrically sy... We consider small vortices, such as tornadoes, dust devils, whirlpools, and small hurricanes at low latitudes, for which the Coriolis force can be neglected. Such vortices are (at least approximately) cylindrically symmetrical about a vertical axis through the center of a calm central region or eye of radius . In the region fluid (gas or liquid) circulates about the eye with speed . We take to be the outer periphery of the vortex, where the fluid speed is reduced to that of the surrounding wind field (in the cases of tornadoes, dust devils, and small hurricanes at low latitudes) or deemed negligible (in the case of whirlpools). If , angular momentum is conserved within the fluid itself;if , angular momentum must be exchanged with Earth to ensure conservation of total angular momentum. We derive the steepness and upper limit of the pressure gradients in vortices. We then discuss the power and energy of vortices. We compare the kinetic energy of atmospheric vortices and the power required to maintain them against frictional dissipation with the same quantities for Earth’s atmosphere as a whole. We explain why the kinetic energy of atmospheric vortices must be replaced on much shorter timescales than is the case for Earth’s atmosphere as a whole. Brief comparisons of cyclostrophic flow with geostrophic and friction-balanced flows are then provided. We then consider an analogy that might be drawn, at least to some extent, with gravitational systems, considering mainly spherically-symmetrical and cylindrically-symmetrical ones. Generation of kinetic energy at the expense of potential energy in fluid vortices, in geostrophic and friction-balanced flows, and in gravitational systems is then briefly discussed. We explain the variations of pressure and gravitational gradients corresponding to generation of kinetic energy exceeding, equaling, and falling short of frictional dissipation. In the Appendix, we describe a simple method for maximizing power extraction from environmental fluid (air or water) flows. In summary, we provide an overview of features and energetics of Earth’s environmental fluid flows and of gravitational analogies thereto that, even though mostly semiquantitative, hopefully may be helpful. 展开更多
关键词 Vortex Cyclostrophic FLOW Angular MOMENTUM pressure Gradient Geostrophic FLOW Friction-Balanced FLOW POWER energy Gravity
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A New Energy-Efficient and Reliable Protocol for Stochastic WSNs Based on Back-Pressure and Entropy of Residual Energy
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作者 Mohammed Almazaideh Janos Levendovszky 《Journal of Computer and Communications》 2020年第11期1-13,共13页
In this paper, a new energy-efficient and reliable routing protocol is introduced for WSNs including a stochastic traffic generation model and a wakeup/sleep mechanism. Our objective is to improve the longevity of the... In this paper, a new energy-efficient and reliable routing protocol is introduced for WSNs including a stochastic traffic generation model and a wakeup/sleep mechanism. Our objective is to improve the longevity of the WSNs by energy balancing but providing reliable packet transfer to the Base Station at the same time. The proposed protocol is based on the principle of the back-pressure method and besides the difference of backlogs, in order to optimize energy consumption, we use a cost function related to an entropy like function defined over the residual energies of the nodes. In the case of two-hop routing the optimal relay node is selected as the one which has maximum backlog difference and keeps the distribution of residual energy as close to uniform as possible where the uniformity is measured by the change of the entropy of the residual energy of the nodes. The protocol assumes Rayleigh fading model. Simulation results show that the proposed algorithm significantly improves the performance of traditional back-pressure protocol with respect to energy efficiency, E2E delay and throughput, respectively. 展开更多
关键词 WSN Back-pressure Routing Protocols Entropy of Residual energy energy Efficiency
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From Pressure-Volume Relationship to Volume-Energy Relationship: A Thermo-Statistical Model for Alveolar Micromechanics
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作者 Kyongyob Min 《Applied Mathematics》 2020年第11期1116-1131,共16页
The connective tissue fiber system and the surfactant system are essential and interdependent components of lung elasticity. Despite considerable efforts over the last decades, we are still far from understanding the ... The connective tissue fiber system and the surfactant system are essential and interdependent components of lung elasticity. Despite considerable efforts over the last decades, we are still far from understanding the quantitative roles of either the connective tissue fiber or the surfactant systems. Through thermo-statistic considerations of alveolar micromechanics, the author introduced a thermo-statistic state function “entropy” to analyze the elastic property of pulmonary parenchyma based on the origami model of alveolar polyhedron. By use of the entropy for alveolar micromechanics, from the logistic equation for the static pressure (<em>P</em>)-volume (<em>V</em>) curves including parameters <em>a</em>, <em>b</em>, <em>c</em>, and <em>k</em> (<em>V</em> - <em>a</em> = <em>b</em>/[1+ exp{-<em>k</em> (<em>P</em> - <em>c</em>)}]), a set of equations was obtained to define the internal energy of lungs (<em>U<sub>L</sub></em>) and its corresponding lung volume (<em>V<sub>L</sub></em>). Then, by use of parameters<em> a</em>, <em>b</em>, <em>c</em>, and <em>k</em>, an individual volume-internal energy (<em>V<sub>L</sub></em><sub> </sub>- <em>U<sub>L</sub></em>) diagram was constructed from reported data in patients on mechanical ventilation. Each <em>V<sub>L</sub></em> - <em>U<sub>L</sub></em> diagram constructed was discussed that its minimal value <em>U<sub>o</sub></em> = <em>c</em> (<em>a</em> + <em>b</em>/2) and its shape parameter <em>b</em>/<em>k</em> represent quantitatively the energy of tissue force and the energy of surface force. Furthermore, by use of the <em>V<sub>L</sub></em><sub> </sub>- <em>U<sub>L</sub></em> relationship, the hysteresis of lungs estimated by entropy production was discussed as dependent on the difference in the number of contributing pulmonary lobules. That is, entropy production might be a novel quantitative indicator to estimate the dynamics of the bronchial tree. These values obtained by combinations of parameters of the logistic P-V curve seem useful indicators to optimize setting a mechanical ventilator. Thus, it is necessary to develop easy tools for fitting the individual sigmoid pressure-volume curve measured in the intensive care unit to the logistic equation. 展开更多
关键词 Thermo-Statistic Entropy Thermodynamic Temperature Sigmoid pressure-Volume Curve Logistic Equation Volume-energy Relationship
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Pressure influence on the Stark effect of impurity states in a strained wurtzite GaN/Al_xGa_(1-x)N heterojunction 被引量:4
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作者 张敏 班士良 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第10期4449-4455,共7页
A variational method is adopted to investigate the properties of shallow impurity states near the interface in a free strained wurtzite GaN/AlxGa1-xN heterojunction under hydrostatic pressure and external electric fie... A variational method is adopted to investigate the properties of shallow impurity states near the interface in a free strained wurtzite GaN/AlxGa1-xN heterojunction under hydrostatic pressure and external electric field by using a simplified coherent potential approximation. Considering the biaxial strain due to lattice mismatch or epitaxial growth and the uniaxial strains effects, we investigated the Stark energy shift led by an external electric field for impurity states as functions of pressure as well as the impurity position, A1 component and areal electron density. The numerical result shows that the binding energy near linearly increases with pressure from 0 to 10 GPa. It is also found that the binding energy as a function of the electric field perpendicular to the interface shows an un-linear red shift or a blue shift for different impurity positions. The effect of increasing x on blue shift is more significant than that on the red shift for the impurity in the channel near the interface. The pressure influence on the Stark shift is more obvious with increase of electric field and the distance between an impurity and the interface. The increase of pressure decreases the blue shift but increases the red shift. 展开更多
关键词 GAN/ALXGA1-XN strain pressure Stark effect binding energy of impurity state
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Experimental Investigation on the Pressure Propagation Mechanism of Tight Reservoirs 被引量:3
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作者 Jing Sun Dehua Liu +2 位作者 Xiang Zhu Wenjun Huang Liang Cheng 《Fluid Dynamics & Materials Processing》 EI 2020年第3期425-440,共16页
Low permeability tight sandstone reservoirs have a high filtrational resistance and a very low fluid flow rate.As a result,the propagation speed of the formation pressure is low and fluid flow behaves as a non-Darcy f... Low permeability tight sandstone reservoirs have a high filtrational resistance and a very low fluid flow rate.As a result,the propagation speed of the formation pressure is low and fluid flow behaves as a non-Darcy flow,which typically displays a highly non-linear behavior.In this paper,the characteristics and mechanism of pressure propagation in this kind of reservoir are revealed through a laboratory pressure propagation experiment and through data from an actual tight reservoir development.The main performance mechanism is as follows:A new pressure cage concept is proposed based on the pressure variation characteristics of the laboratory experiments.There are two methods of energy propagation in the actual water injection process:one is that energy is transmitted to the deep reservoir by the fluid flowing through the reservoir,and the other is that energy is transmitted by the elasticity of the reservoir.For one injection well model and one production well model,the pressure distribution curve between the injection and production wells,as calculated by the theoretical method,has three section types,and they show an oblique“S”shape with a straight middle section.However,the actual pressure distribution curve is nonlinear,with an obvious pressure advance at the front.After the injection pressure increases to a certain level,the curve shape is an oblique and reversed“S”shape.Based on the research,this paper explains the deep-seated reasons for the difference in pressure distribution and proposes that it is an effective way to develop low permeability tight reservoirs using the water injection supplement energy method. 展开更多
关键词 Low permeability tight reservoir pressure propagation pressure cage formation energy
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Numerical simulation on the pressure wave in a 30 mm electrothermal-chemical gun with the discharge rod plasma generator 被引量:1
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作者 Yan-jie Ni Yong Jin +1 位作者 Gang Wan Bao-ming Li 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2019年第5期674-679,共6页
An axisymmetric two-dimensional(2D)internal ballistic model including the transient burning rate law is used to simulate the 30mm electrothermal-chemical(ETC)launch with the discharge rod plasma generator(DRPG).The re... An axisymmetric two-dimensional(2D)internal ballistic model including the transient burning rate law is used to simulate the 30mm electrothermal-chemical(ETC)launch with the discharge rod plasma generator(DRPG).The relationship between the pressure wave and the initial parameters,such as input electric power,discharging timing sequence,loading density and propellant web thickness,is researched through the change of initial parameters in the model.In the condition of synchronous discharging,the maximum of the pressure wave can be controlled while the ratio of the input electric energy to the propellant chemical energy(electric energy ratio)is less than 0.11.If the electric energy ratio is larger than 0.11,the maximum of the pressure wave increases rapidly with the electric energy ratio.With the increasing of the electric energy ratio,the change of the first negative amplitude value can be ignored.In the condition of timing sequence discharging,the allowed input electric energy ratio to control the pressure wave is proportional to the current pulse duration.At the high electric energy ratio,the maximum of the pressure wave is inverse proportional to the current pulse duration.The pressure wave increases with the increasing of the loading density.But the allowed electric energy ratio to control the pressure wave and the variation trend of the first negative amplitude wave value doesn't change.During the discharging of the DRPG,the influence of changing propellant web thickness in ETC launch can be ignored. 展开更多
关键词 Electrothermal-chemical LAUNCH pressure wave Plasma SOLID PROPELLANT Electric energy ratio
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