为提高大型风电场并网可靠性,该文基于严密的数学统计方法,提出了一种以控制风电场出线功率控制偏差(wind power control error,WPCE)为考核目标的风电场控制性能评价标准(wind control performance standard,WCPS)。该标准以随机变量...为提高大型风电场并网可靠性,该文基于严密的数学统计方法,提出了一种以控制风电场出线功率控制偏差(wind power control error,WPCE)为考核目标的风电场控制性能评价标准(wind control performance standard,WCPS)。该标准以随机变量统计特性为依据制定,着眼于长期的控制性能,更能如实描述和反映风电出力随机性和不确定性的特点和要求,达到更好的控制目的。基于WCPS标准,提出了风电场配置的储能系统的充放电控制策略,以平抑风电出力波动性,提高风电的消纳能力。最后,以某风电场日负荷数据为例验证该控制标准和控制策略的可行性和有效性。仿真结果表明,所提控制策略大幅减小了风电预测误差,有效地减少储能系统的充放电调节次数,缓解备用机组的负担,降低电网调节成本,提高电网对风电的吸纳能力,对电力市场模式下的风电场接入系统具有指导意义。展开更多
以尿素为氮源,对碳纤维表面进行改性,制备了一种新型海洋电极,并测试了其电化学性能和电场响应性能。结果表明,碳纤维表面的含氧和含氮基团对其电化学性能具有显著的影响,与尿素反应并在450℃条件下热处理的碳纤维具有最低的内阻和最大...以尿素为氮源,对碳纤维表面进行改性,制备了一种新型海洋电极,并测试了其电化学性能和电场响应性能。结果表明,碳纤维表面的含氧和含氮基团对其电化学性能具有显著的影响,与尿素反应并在450℃条件下热处理的碳纤维具有最低的内阻和最大的比电容。电化学性能的变化也直接影响碳纤维电极对的电场性能,450℃条件下热处理的碳纤维电极也具有最佳的电场性能:电极对极差稳定性降到0.1 m V/24 h左右,自噪声为2.2 n V/rt Hz@1Hz,电极对能较好地响应出1 m Hz、1 m V电场信号。展开更多
The development of offshore wind farms was originally carried out in shallow water areas with fixed （seabed mounted） structures. However, countries with limited shallow water areas require innovative floating platfo...The development of offshore wind farms was originally carried out in shallow water areas with fixed （seabed mounted） structures. However, countries with limited shallow water areas require innovative floating platforms to deploy wind turbines offshore in order to harness wind energy to generate electricity in deep seas. The performances of motion and mooring system dynamics are vital to designing a cost effective and durable floating platform. This paper describes a numerical model to simulate dynamic behavior of a new semi-submersible type floating offshore wind turbine （FOWT） system. The wind turbine was modeled as a wind block with a certain thrust coefficient, and the hydrodynamics and mooting system dynamics of the platform were calculated by SESAM soRware. The effect of change in environmental conditions on the dynamic response of the system under wave and wind loading was examined. The results indicate that the semi-submersible concept has excellent performance and SESAM could be an effective tool for floating wind turbine design and analysis.展开更多
LiFePO4/C composites were synthesized by a molten salt (MS) method using the mixture of LiCl,LiOH and NaCl.The prepared LiFePO4/C composites are characterized by X-ray diffractometry (XRD),field emission scanning elec...LiFePO4/C composites were synthesized by a molten salt (MS) method using the mixture of LiCl,LiOH and NaCl.The prepared LiFePO4/C composites are characterized by X-ray diffractometry (XRD),field emission scanning electron microscopy (FESEM) and charge-discharge test.XRD patterns indicate that LiFePO4 prepared in the temperature range of 550-700 ℃ crystallizes well in an olivine-type structure.Through FESEM images,the sphere-like and homogeneous particles of 0.2 μm can be observed.The charge-discharge test shows that the materials prepared at 600 ℃ for 12 h have good electrochemical performance.At the rates of 0.2C (34 mA/g) and 0.5C,the discharge capacities are 144.6 and 122.3 mA·h/g,respectively,together with good cycle performances.展开更多
In this work,the chromium aluminum nitride(CrAlN)coatings were prepared on TC11 titanium alloy by composite magnetic field cathodic arc ion plating with controllable pulse electromagnetic combined with permanent magne...In this work,the chromium aluminum nitride(CrAlN)coatings were prepared on TC11 titanium alloy by composite magnetic field cathodic arc ion plating with controllable pulse electromagnetic combined with permanent magnet.The effects of electromagnetic frequency on the morphology,microstructure,nano-hardness and elastic modulus of the coatings were investigated by scanning electron microscope(SEM),X-ray diffraction(XRD)and nano-indenter.This paper has mainly studied the influence of CrAlN coatings which are prepared at various electromagnetic frequencies on the wear and erosion resistance through a series of wear and solid particle erosion experiments.It was found that the deposition rate of CrAlN coatings increases with the increase of electromagnetic frequency.And CrAlN coatings all preferentially grew along the(111)crystal plane.At 16.7 Hz,with the increase of pulsed electromagnetic frequency,the hardness is the highest(23.6 GPa)and the adhesion is the highest(41.5 N).In addition,the coating deposition exhibited the best wear and solid erosion resistance at 16.7 Hz and 33.3 Hz,the friction coefficient is about 0.35,and the erosion rate is about 0.2μm/g at 30°and less than 1μm/g at 90°,respectively.These results indicate that the CrAlN coating formed at an appropriate pulsed electromagnetic frequency can achieve excellent mechanical properties,wear and solid erosion resistance.展开更多
Analytical solutions for a Griffith crack inside an infinite piezoel ectromagnetic medium under combined mechanical-electrical-magnetic loadings are formulated using integral transform method. The singular stress, ele...Analytical solutions for a Griffith crack inside an infinite piezoel ectromagnetic medium under combined mechanical-electrical-magnetic loadings are formulated using integral transform method. The singular stress, electric and magnetic fields in the piez oelectromagnetic material are obtained by the theory of linear piezoelectromagneticity. Fourier transforms are used to reduce the mixed boundary value problems of the crack, which is assumed to b e permeable, to dual integral equations. The solution of the dual integral equations is then ex pressed analytically. Expressions for strains, stresses, electric fields, electric displacements, mag netic fields and magnetic inductions in the vicinity of the crack tip are derived. Field intensi ty factors and energy release rate for piezoelectromagnetic material are obtaine d. The stresses, electric displacements and magnetic inductions at the crack tip show the traditional square root singu larities; and the electric field intensity factor (EFIF) and the magnetic field intensity factor (MFIF) are always zero.展开更多
In the work, we studied the effect of the plasma of a runaway electron preionized （REP） diffuse discharge （DD） on the composition, structure, and properties of ST3PS steel surface layers. Voltage pulses with an in...In the work, we studied the effect of the plasma of a runaway electron preionized （REP） diffuse discharge （DD） on the composition, structure, and properties of ST3PS steel surface layers. Voltage pulses with an incident wave amplitude of up to 30 kV, FWHM of around 4 ns, and rise time of around 2.5 ns were applied to the gap in an inhomogeneous electric field. The ST3PS steel specimens exposed to this type of discharge revealed changes in their defect subsystem, suggesting that the runaway electron preionized diffuse discharge provides surface hardening of the steel.展开更多
The aim of this work is double. Firstly, we want to stress out that investing in renewable energies in 2009 in Spain was a profitable activity. This question will be answered studying the possibilities of expanding ＂...The aim of this work is double. Firstly, we want to stress out that investing in renewable energies in 2009 in Spain was a profitable activity. This question will be answered studying the possibilities of expanding ＂Sierra de Tineo＂ wind farm in the Principality of Asturias （location, wind resource, data analysis, simulation, legal standards and economic and sensitivity study of the investment）, and for that, data from the year 2009 have been used. And secondly, the goal is to set the bases for a future paper where the current situation of Spain （within the renewable framework）, will be compared with the 2009 scenario.展开更多
To study the electromechanical stability of dielectric elastomer subjected to a mechanical force field, we use free energy functions of variable forms to analyze the mechanical performance of dielectric elastomer. The...To study the electromechanical stability of dielectric elastomer subjected to a mechanical force field, we use free energy functions of variable forms to analyze the mechanical performance of dielectric elastomer. The relation among critical nominal electric field, critical true electric field, nominal stress and mechanical force field is derived. These calculations agree well with the experimental results. The results can help us better understand the stability conditions of dielectric elastomers and furthermore guide the design and manufacture of sensors and actuators based on dielectric elastomers.展开更多
文摘为提高大型风电场并网可靠性,该文基于严密的数学统计方法,提出了一种以控制风电场出线功率控制偏差(wind power control error,WPCE)为考核目标的风电场控制性能评价标准(wind control performance standard,WCPS)。该标准以随机变量统计特性为依据制定,着眼于长期的控制性能,更能如实描述和反映风电出力随机性和不确定性的特点和要求,达到更好的控制目的。基于WCPS标准,提出了风电场配置的储能系统的充放电控制策略,以平抑风电出力波动性,提高风电的消纳能力。最后,以某风电场日负荷数据为例验证该控制标准和控制策略的可行性和有效性。仿真结果表明,所提控制策略大幅减小了风电预测误差,有效地减少储能系统的充放电调节次数,缓解备用机组的负担,降低电网调节成本,提高电网对风电的吸纳能力,对电力市场模式下的风电场接入系统具有指导意义。
文摘以尿素为氮源,对碳纤维表面进行改性,制备了一种新型海洋电极,并测试了其电化学性能和电场响应性能。结果表明,碳纤维表面的含氧和含氮基团对其电化学性能具有显著的影响,与尿素反应并在450℃条件下热处理的碳纤维具有最低的内阻和最大的比电容。电化学性能的变化也直接影响碳纤维电极对的电场性能,450℃条件下热处理的碳纤维电极也具有最佳的电场性能:电极对极差稳定性降到0.1 m V/24 h左右,自噪声为2.2 n V/rt Hz@1Hz,电极对能较好地响应出1 m Hz、1 m V电场信号。
基金Foundation item： Supported by the 111 Project under Grant No.B07019, and the National Natural Science Foundation of China under Grant No.50979020.
文摘The development of offshore wind farms was originally carried out in shallow water areas with fixed （seabed mounted） structures. However, countries with limited shallow water areas require innovative floating platforms to deploy wind turbines offshore in order to harness wind energy to generate electricity in deep seas. The performances of motion and mooring system dynamics are vital to designing a cost effective and durable floating platform. This paper describes a numerical model to simulate dynamic behavior of a new semi-submersible type floating offshore wind turbine （FOWT） system. The wind turbine was modeled as a wind block with a certain thrust coefficient, and the hydrodynamics and mooting system dynamics of the platform were calculated by SESAM soRware. The effect of change in environmental conditions on the dynamic response of the system under wave and wind loading was examined. The results indicate that the semi-submersible concept has excellent performance and SESAM could be an effective tool for floating wind turbine design and analysis.
基金Project(06B002) supported by the Scientific Research Fund of Hunan Provincial Education Department of ChinaProject(09JJ3092) supported by the Natural Science Foundation of Hunan Province,ChinaProject(2008FJ3008) supported by the Planned Science and Technology Project of Hunan Province,China
文摘LiFePO4/C composites were synthesized by a molten salt (MS) method using the mixture of LiCl,LiOH and NaCl.The prepared LiFePO4/C composites are characterized by X-ray diffractometry (XRD),field emission scanning electron microscopy (FESEM) and charge-discharge test.XRD patterns indicate that LiFePO4 prepared in the temperature range of 550-700 ℃ crystallizes well in an olivine-type structure.Through FESEM images,the sphere-like and homogeneous particles of 0.2 μm can be observed.The charge-discharge test shows that the materials prepared at 600 ℃ for 12 h have good electrochemical performance.At the rates of 0.2C (34 mA/g) and 0.5C,the discharge capacities are 144.6 and 122.3 mA·h/g,respectively,together with good cycle performances.
基金Projects(2017GDAS CX-0202,2017GDAS CX-0111,2018 GDAS CX-0402) supported by Guangdong Academy of Science’ Special Project of Science and Technology Development,ChinaProject(2014B070705007) supported by Guangdong Science and Technology Plan Project,China+1 种基金Project(2016A030312015) supported by Scientific Research Fund of Guangdong Province,ChinaProject(2017A070701027) supported by Guangdong Science and Technology Program,China。
文摘In this work,the chromium aluminum nitride(CrAlN)coatings were prepared on TC11 titanium alloy by composite magnetic field cathodic arc ion plating with controllable pulse electromagnetic combined with permanent magnet.The effects of electromagnetic frequency on the morphology,microstructure,nano-hardness and elastic modulus of the coatings were investigated by scanning electron microscope(SEM),X-ray diffraction(XRD)and nano-indenter.This paper has mainly studied the influence of CrAlN coatings which are prepared at various electromagnetic frequencies on the wear and erosion resistance through a series of wear and solid particle erosion experiments.It was found that the deposition rate of CrAlN coatings increases with the increase of electromagnetic frequency.And CrAlN coatings all preferentially grew along the(111)crystal plane.At 16.7 Hz,with the increase of pulsed electromagnetic frequency,the hardness is the highest(23.6 GPa)and the adhesion is the highest(41.5 N).In addition,the coating deposition exhibited the best wear and solid erosion resistance at 16.7 Hz and 33.3 Hz,the friction coefficient is about 0.35,and the erosion rate is about 0.2μm/g at 30°and less than 1μm/g at 90°,respectively.These results indicate that the CrAlN coating formed at an appropriate pulsed electromagnetic frequency can achieve excellent mechanical properties,wear and solid erosion resistance.
文摘Analytical solutions for a Griffith crack inside an infinite piezoel ectromagnetic medium under combined mechanical-electrical-magnetic loadings are formulated using integral transform method. The singular stress, electric and magnetic fields in the piez oelectromagnetic material are obtained by the theory of linear piezoelectromagneticity. Fourier transforms are used to reduce the mixed boundary value problems of the crack, which is assumed to b e permeable, to dual integral equations. The solution of the dual integral equations is then ex pressed analytically. Expressions for strains, stresses, electric fields, electric displacements, mag netic fields and magnetic inductions in the vicinity of the crack tip are derived. Field intensi ty factors and energy release rate for piezoelectromagnetic material are obtaine d. The stresses, electric displacements and magnetic inductions at the crack tip show the traditional square root singu larities; and the electric field intensity factor (EFIF) and the magnetic field intensity factor (MFIF) are always zero.
文摘In the work, we studied the effect of the plasma of a runaway electron preionized （REP） diffuse discharge （DD） on the composition, structure, and properties of ST3PS steel surface layers. Voltage pulses with an incident wave amplitude of up to 30 kV, FWHM of around 4 ns, and rise time of around 2.5 ns were applied to the gap in an inhomogeneous electric field. The ST3PS steel specimens exposed to this type of discharge revealed changes in their defect subsystem, suggesting that the runaway electron preionized diffuse discharge provides surface hardening of the steel.
文摘The aim of this work is double. Firstly, we want to stress out that investing in renewable energies in 2009 in Spain was a profitable activity. This question will be answered studying the possibilities of expanding ＂Sierra de Tineo＂ wind farm in the Principality of Asturias （location, wind resource, data analysis, simulation, legal standards and economic and sensitivity study of the investment）, and for that, data from the year 2009 have been used. And secondly, the goal is to set the bases for a future paper where the current situation of Spain （within the renewable framework）, will be compared with the 2009 scenario.
文摘To study the electromechanical stability of dielectric elastomer subjected to a mechanical force field, we use free energy functions of variable forms to analyze the mechanical performance of dielectric elastomer. The relation among critical nominal electric field, critical true electric field, nominal stress and mechanical force field is derived. These calculations agree well with the experimental results. The results can help us better understand the stability conditions of dielectric elastomers and furthermore guide the design and manufacture of sensors and actuators based on dielectric elastomers.
