Optimal scheduling of zero-carbon park considering variational characteristics of hydrogen energy storage systems

Zero-carbon parks have broad prospects in carbon neutralization.As an energy hub,hydrogen energy storage plays an important role in zero-carbon parks.However,the nonlinear characteristics of hydrogen energy storage systems(HESSs)have a significant impact on the system economy.Therefore,considering the variable working condition characteristics of HESSs,a hybrid operation method is proposed for HESS,to support the efficient and economic operation of zero-carbon parks,By analyzing the operating principle of a zero-carbon park with HESS,the system structure framework and variable condition linearization model of the equipment in HESS are established.Moreover,considering the energy output characteristics of hydrogen energy storage equipment under variable working conditions,a multimodule hybrid operation strategy is proposed for electrolytic and fuel cells,effectively meeting the thermoelectric load demand of zero-carbon parks in different scenarios.Finally,the economy of the proposed hybrid operation strategy was verified in typical scenarios,using a zero-carbon park embedded with a HESS.

Spatiotemporal variations,influencing factors,and configurational promotion paths of energy efficiency in China’s cities

The promotion of energy efficiency(EE)helps address energy constraints and promote environmental sustainability.This study comprehensively explores the spatiotemporal variations,influencing factors,and configuration promotion paths of EE in 284 Chinese cities during 2003‒2019 using the global super-efficiency minimum distance to strong efficient frontier(G-S-MinDS),exploratory spatial data analysis(ESDA),multiscale geographically weighted regression(MGWR),and fuzzy set qualitative comparative analysis(fsQCA)methods.The findings are:①China’s cities have an annual average EE of 0.658 with a growth rate of 0.53%,showing considerable promotion potential.②Industrial structure optimization,population agglomeration,economic development,and increased green coverage contribute positively,while government intervention and openness hinder China’s urban EE.③Four configurational promotion paths for enhancing China’s urban EE are identified,where among those paths population density is a core condition,while government intervention is not.This study provides valuable insights into substantially improving urban EE,emphasizing the need for targeted policies to address energy and environmental crises in China.

Three-year Variations of Water, Energy and CO_2 Fluxes of Cropland and Degraded Grassland Surfaces in a Semi-arid Area of Northeastern China

Based on 3 years （2003-05） of the eddy covariance （EC） observations on degraded grassland and cropland surfaces in a semi-arid area of Tongyu （44°25′N, 122°52′E, 184 m a.s.1.）, Northeast China, seasonal and annual variations of water, energy and CO2 fluxes have been investigated. The soil moisture in the thin soil layer （at 0.05, 0.10 and 0.20 m） clearly indicates the pronounced annual wet-dry cycle; the annual cycle is divided into the wet （growing season） and dry seasons （non-growing season）. During the growing season （from May to September）, the sensible and latent heat fluxes showed a linear dependence on the global solar radiation. However, in the non-growing season, the latent heat flux was always less than 50 W m^-2, while the available energy was dissipated as sensible, rather than latent heat flux. During the growing season in 2003-05, the daily average sensible and latent heat fluxes were larger on the cropland surface than on the degraded grassland surface. The cropland ecosystem absorbed more CO2 than the degraded grassland ecosystem in the growing season in 2003-05. The total evapotranspiration on the cropland was more than the total precipitation, while the total evapotranspiration on the degraded grassland was almost the same as the total annual precipitation in the growing season. The soil moisture had a good correlation with the rainfall in the growing season. Precipitation in the growing season is an important factor on the water and carbon budget in the semi-arid area.

Seasonal variation in body mass and energy budget in Chinese bulbuls (pycnonotus sinensis)

Background: Seasonal adjustments in body mass and energy budget are important for the survival of small birds in temperate zones. Seasonal changes in body mass, body temperature, gross energy intake(GEI), digestible energy intake(DEI), body fat content, as well as length and mass of the digestive tract, were measured in Chinese Bulbuls(Pycnonotus sinensis) caught in the wild at Wenzhou, China.Methods: Body mass was determined with a Sartorius balance. The caloric contents of the dried food and feces were then determined using a oxygen bomb calorimeter. Total fat was extracted from the dried carcasses by ether extraction in a Soxhlet apparatus. The digestive tract of each bird was measured and weighed, and was then dried to a constant mass.Results: Body mass showed a significant seasonal variation and was higher in spring and winter than in summer and autumn. Body fat was higher in winter than in other seasons. GEI and DEI were significantly higher in winter.The length and mass of the digestive tract were greatest in winter and the magnitude of both these parameters was positively correlated with body mass, GEI and DEI. Small passerines typically have higher daily energy expenditure in winter, necessitating increased food consumption.Conclusions: This general observation is consistent with the observed winter increase in gut volume and body mass in Chinese Bulbuls. These results suggest that Chinese Bulbuls adjust to winter conditions by increasing their body mass, body fat, GEI, DEI and digestive tract size.

Seasonal variations in the energy budget of Elliot's pheasant (Syrmaticus ellioti) in cage

This study aimed to discuss the energy budget of Elliot's pheasant Syrmaticus ellioti in different seasons, with life and health, good growth and normal digestion of Elliot's pheasant as the tested objects, The energy budget of Elliot's pheasant was measured by daily collection of the trial pheasants' excrement in the biological garden of Guangxi Normal University from March 2011 to February 2012. The results showed that the gross energy consumption, metabolic energy and excrement energy varied by season, increasing as temperature decreased. There was significant difference in gross energy consumption, metabolic energy, excrement energy between adults and nonages. There was also a trend that food digestibility of pheasants increases as temperature increases. In the same season, the food digestibility of adults was better than that of nonages. Throughout spring, summer, autumn and winter, the metabolic energy of 4-year adults were 305.77±13.40 kJ/d, 263.67±11.89 kJ/d, 357.23±25.49 kJ/d and 403.12±24.91 kJ/d, respectively, and the nonages were 284.86±17.22 kJ/d, 284. 66±15.16 kJ/d, 402. 26±31.46 kJ/d and 420. 30±31.98 kJ/d, respectively. The minimum metabolic energies were 247.65±21.81 g, 265.86±26.53 g, respectively for each group, detected between 4-year adults and 1-year nonages. Further study is needed to determine whether 29.6 C is the optimal temperature for the Elliot's pheasant.

The spatiotemporal variation of the wind-induced near-inertial energy flux in the mixed layer of the South China Sea

On the basis of the QSCAT/NCEP blended wind data and simple ocean data assimilation （SODA）, the wind-induced near-inertial energy flux （NIEF） in the mixed layer of the South China Sea （SCS） is estimated by a slab model, and the model results are verified by observational data near the Xisha Islands in the SCS. Then, the spatial and temporal variations of the NIEF in the SCS are analyzed. It is found that, the monthly mean NIEF exhibits obvious spatial and temporal variabilities, i.e., it is large west of Luzon Island all the year, east of the Indo-China Peninsula all the year except in spring, and in the northern SCS from May to Septem- ber. The large monthly mean NIEF in the first two zones may be affected by the large local wind stress curl whilst that in the last zone is probably due to the shallow mixed layer depth. Moreover, the monthly mean NIEF is relatively large in summer and autumn due to the passage of typhoons. The spatial mean NIEF in the mixed layer of the SCS is estimated to be about 1.25 mW/m2 and the total wind energy input from wind is approximately 4.4 GW. Furthermore, the interannual variability of the spatial monthly mean NIEF and the Nifio3.4 index are negatively correlated.

Spatial and temporal variation of energy carbon emissions in Yantai from 2001 to 2011

In order to understand the characteristics of spatial and temporal variation,as well as provide effective ideas on carbon emissions and regulatory policy in Yantai,this article analyzed spatial and temporal variation of carbon emissions in Yantai based on energy consumption statistics for a variety of energy sorts together with industrial sectors from 2001 to 2011.The results were as following:First of all,Yantai's carbon emissions grew by an average of 5.5%per year during the last 10 years,and there was a peak of 10.48 million carbon in the year of 2011.Second,compared with the gross domestic product(GDP) growth rate,the figures for energy carbon emissions growth rate were smaller;however the problem of carbon emissions were still more obvious.Furthermore,carbon emissions in Yantai increased rapidly before 2008;while after 2008,it increased more slowly and gradually become stable.Third,the energy consumption was different among regions in Yantai.For instance,the energy consumption in Longkou city was the largest,which occupied 50%of the total carbon emissions in Yantai;and the energy consumption in Chang Island was generally less than 1%of the Longkou consumption.Finally,there were relative close relationships among the spatial difference of carbon emissions,regional resources endowment,economic development,industrial structure,and energy efficiency.

The Influences of Energy Price Variation on the Prices of Other Industries: A Study Based on Input-Output Price Model

Energy has laid material foundation for human society during its development. Meanwhile, any change of price in the energy industry may influence social production and people’s life at all levels via an input-output mechanism under which the change related to energy is surely transmitted to other industries. The price change thus incurred in all industries may adversely affect the realization of macroeconomic objective-maintaining prices at a stable level. It is, therefore, needed to conduct an empirical research related to the impact of price change in energy industry on that in other industries. According to the data coming from “China’s 2015 Input-Output Extension Table (42 Departments)” and four hypothetical basis, this article focuses on four energy sectors and analyzes how deeply the price change of them, by use of input-output model, affects that of other industrial products under five conditions where each of their price rises by 10% individually or simultaneously, and why such an influence occurs. The results show that the price rising of the energies in question leads to an upward growth in the prices of other industrial products, especially when their prices go up simultaneously. Besides, the price increase in the four energy sectors doesn’t influence other industries in an accumulation form but actually leads to a rollback in some of other industries. It is recommended to adopt diversified pricing strategies for different energy products, thus maximizing the value of each specific energy, and meanwhile achieving the goals of energy consumption reduction and price equilibrium.

Seasonal variations in the energy budget of Elliot’s pheasant (Syrmaticus ellioti) in cage

This study aimed to discuss the energy budget of Elliot’s pheasant Syrmaticus ellioti in different seasons,with life and health,good growth and normal digestion of Elliot’s pheasant as the tested objects,The energy budget of Elliot’s pheasant was measured by daily collection of the trial pheasants’excrement in the biological garden of Guangxi Normal University from March 2011 to February 2012.The results showed that the gross energy consumption,metabolic energy and excrement energy varied by season,increasing as temperature decreased.There was significant difference in gross energy consumption,metabolic energy,excrement energy between adults and nonages.There was also a trend that food digestibility of pheasants increases as temperature increases.In the same season,the food digestibility of adults was better than that of nonages.Throughout spring,summer,autumn and winter,the metabolic energy of 4-year adults were 305.77±13.40 kJ/d,263.67±11.89 kJ/d,357.23±25.49 kJ/d and 403.12±24.91 kJ/d,respectively,and the nonages were 284.86±17.22 kJ/d,284.66±15.16 kJ/d,402.26±31.46 kJ/d and 420.30±31.98 kJ/d,respectively.The minimum metabolic energies were 247.65±21.81 g,265.86±26.53 g,respectively for each group,detected between 4-year adults and 1-year nonages.Further study is needed to determine whether 29.6 C is the optimal temperature for the Elliot’s pheasant.

Analytical solution to mapping rail deformation under bridge transverse deformation using energy variational principle

The track geometry is a critical factor that affects the running safety and riding comfort of trains moving on a high-speed railway bridge.This study addresses the mapping relationship between the track deformation and lateral deformations of bridges.Equilibrium equations and natural boundary conditions of the track-bridge system are established based on the energy variational principle,and an analytical solution is derived for the track deformation accounting for lateral bridge deformations.A five-span simply-supported bridge with continuous welded rail has been selected as the case study.The mapping rail deformations are compared to the finite element results,and both results agree well with each other,validating the analytical method proposed in this paper.The influence factors on the mapping rail deformation are further evaluated.Results show that the mapping rail deformation is consistent with the girder displacement at the area that is away from the girder ends when the flexural stiffness ratio between the track and the bridge girder is low.The interlayer stiffness has a significant effect on the mapping rail deformation when the track flexural stiffness is of a high value.

The Seasonal Variation of Large Volume Airgun Signals in Hutubi,Xinjiang

In order to study the seasonal variation of large volume airgun signals in Hutubi,Xinjiang,we analyzed 2,936 signals of airgun source excitations during 2015-2016 received by a seismograph on the bank of the excitation pool.Firstly,the RMS value of the signal amplitude and the daily average temperature were compared after linearly superimposing the signal in days,to analyze the influence of the surface ice cover on the excitation energy release of the airgun source.The result shows that the ice cover will reduce the excitation energy,and the thicker the ice cover is,the more obvious the excitation energy reduces.Secondly,the time-frequency analysis method was used to analyze the influence of the surface ice cover on the signal frequency.It is concluded that the existence of the ice cover has little effect on the signal frequency,but it will affect the intensity of the signal around 4 Hz between 1-2 s after excitation.The cause of these phenomena is that the ice cover affects the bubble oscillation,which in turn affects the energy conversion.The study shows that when using the cross-correlation delay method to calculate the wave velocity,the signals can be divided into two periods according to the daily average temperature:with or without ice cover on the upper surface of the excitation pool.This can help eliminate the influence of the source variation and improve the accuracy of the monitoring results.

GENERALIZED VARIATIONAL PRINCIPLES OF THE VISCOELASTIC BODY WITH VOIDS AND THEIR APPLICATIONS

From the Boltzmann's constitutive law of viscoelastic materials and the linear theory of elastic materials with voids, a constitutive model of generalized force fields for viscoelastic solids with voids was given. By using the variational integral method, the convolution-type functional was given and the corresponding generalized variational principles and potential energy principle of viscoelastic solids with voids were presented. It can be shown that the variational principles correspond to the differential equations and the initial and boundary conditions of viscoelastic body with voids. As an application, a generalized variational principle of viscoelastic Timoshenko beams with damage was obtained which corresponds to the differential equations of generalized motion and the initial and boundary conditions of beams. The variational principles provide a way for solving problems of viscoelastic solids with voids.

VARIATIONAL PRINCIPLES OF ASYMMETRIC ELASTICITY THEORY OF FINITE DEFORMATION

In this paper, based on the finite deformation S-R decomposition theorem, the definition of the body moment is renewed as the stem of its internal and external. The expression of the increment rate of the deformation energy is derived and the physical meaning is clarified. The power variational principle and the complementary power variational principle for finite deformation mechanics are supplemented and perfected.

The Influence of Radial Area Variation on Wind Turbines to the Axial Induction Factor

Improvements in the aerodynamic design will lead to more efficiency of wind turbines and higher power production. In the present study, a 3D parametric gas turbine blade geometry building code, 3DBGB, has been modified in order to include wind turbine design capabilities. This approach enables greater flexibility of the design along with the ability to design more complex geometries with relative ease. The NREL NASA Phase VI wind turbine was considered as a test case for validation and as a baseline by which modified designs could be compared. The design parameters were translated into 3DBGB input to create a 3D model of the wind turbine which can also be imported into any CAD program. Design modifications included replacing the airfoil section and modifying the thickness to chord ratio as a function of span. These models were imported into a high-fidelity CFD package, Fine/TURBO by NUMECA. Fine/TURBO is a specialized CFD platform for turbo-machinery analysis. A code-geomturbo was used to convert the 3D model of the wind turbine into the native format used to define geometries in the Fine/TURBO meshing tool, AutoGrid. The CFD results were post processed using a 3D force analysis code. The radial force variations were found to play a measurable role in the performance of wind turbine blades. The radial component of the blade surface area as it varies in span is the dominant contributor of the radial forces. Through the radial momentum equation, this radial force variation is responsible for creating the streamline curvature that leads to the expansion of the streamtube (slipstream) that is responsible for slowing the wind velocity ahead of the wind turbine leading edge, which is quantified as the axial induction factor. These same radial forces also play a role in changing the slipstream for propellers. Through the design modifications, simulated with CFD and post-processed appropriately, this connection with the radial component of area to the radial forces to the axial induction factor, and finally the wind turbine power is demonstrated. The results from the CFD analysis and 3D force analysis are presented. For the case presented, the power increases by 5.6% due to changes in airfoil thickness only.

Short-term variations and influencing factors of suspended sediment concentrations at the Heisha Beach,Guangdong,China

Knowledge of sediment variation processes is essential to understand the evolution mechanism of beach morphology changes.Thus,a field measurement was conducted at the Heisha Beach,located on the west coast of the Zhujiang River(Pearl River)Estuary,to investigate the short-term variation in suspended sediment concentrations(SSCs)and the relationship between the SSC and turbulent kinetic energy,bottom shear stress(BSS),and relative wave height.Based on extreme event analysis results,extreme events have a greater influence on turbulent kinetic energy than SSC.Although a portion of the turbulent kinetic energy dissipates directly into the water column,it plays an important role in suspended sediment motion.Most of the time,the wave-current interaction is strong enough to drive sediment incipience and resuspension.When combined,the wave-current interaction and wave-induced BSSs have a greater influence on suspended sediment transport and SSC variation than current-induced BSS alone.The relative wave height also has a strong correlation with SSC,indicating that the combined effect of water depth and wave height significantly impacts SSC variation.Water depth is mainly controlled by the tide on the beaches;thus,the effects of tides and waves should be conjunctively considered when analyzing the factors influencing SSC.

Area Variation Based Color Snake Algorithm for Moving Object Tracking

A snake algorithm has been known that it has a strong point in extracting the exact contour of an object. But it is apt to be influenced by scattered edges around the control points. Since the shape of a moving object in 2D image changes a lot due to its rotation and translation in the 3D space, the conventional algorithm that takes into account slowly moving objects cannot provide an appropriate solution. To utilize the advantages of the snake algorithm while minimizing the drawbacks, this paper proposes the area variation based color snake algorithm for moving object tracking. The proposed algorithm includes a new energy term which is used for preserving the shape of an object between two consecutive images. The proposed one can also segment precisely interesting objects on complex image since it is based on color information. Experiment results show that the proposed algorithm is very effective in various environments.

Effect of Variation of the Coefficient of Friction on the Temperature at the Level of the Fault Lips

Earth’s crust is an anisotropic and purely heterogeneous medium, which is justified by existence of different discontinuities;our study aims to show the effect of the variation of coefficient of friction on the evolution of temperature and its impact on seismic forecasting. In this work, we are model in 2D the variation of thermal energy and temperature produced by friction at the level of fault lip as function of depth of the seismic focus and at different value of time. Earthquakes are born when the energy accumulated by friction at the level of fault is suddenly released causing damage, sometimes noticeable on the surface of earth (macroseisms), and sometimes not at all noticeable on the surface of earth (microseisms), then energy which occurs before is important to forecasting earthquake. Assuming that coefficient of friction is variable, our results have enabled us to highlight the fact that, the greater the coefficient of friction, more the temperature increases, although the temperature profile increase over time but not linearly reflecting the presence of different asperities and discontinuities zone;slip generated at the level of fault occur a variation of temperature on specific points called roughness in common agreement with the literature. A large part of energy produced by friction is dissipated in heat causing a local increases in temperature which a very short duration and called flash contact temperature, and that despite the fact that the temperature evolved in time and space, it all converged towards a perfectly distinguishable fixed point.

变截面波形钢腹板悬臂梁抗剪性能研究

为了在变截面波形钢腹板悬臂梁的剪应力计算时考虑翼板、腹板以及组合箱梁截面转角差异,首先从翼板、腹板以及组合箱梁截面转角出发建立位移函数,采用能量变分法将翼板与腹板承剪进行剥离,利用弯矩等效分离顶、底板承剪;其次结合变截面波形钢腹板组合箱梁的梁段分析单元刚度矩阵及节点荷载列阵建立了剪应力求解程序;最后分析了悬臂梁在不同荷载工况下顶、底板及腹板剪应力与承剪比.结果表明:相较于有限元计算结果,考虑转角差异后顶板、腹板和底板承剪比计算结果较已有变截面剪应力计算结果精度最大可提高3.48%、3.43%和6.91%;悬臂梁各组件承剪比取决于荷载形式,梁端集中荷载作用下,顶、底板各自承剪比达到最大,分别为自由端的12.82%和固定端的60.81%;均布荷载作用下,腹板承剪比达到最大,为自由端的78.11%.

基于动态优化周期的风光氢储耦合系统改进能量管理策略

电/氢混合储能对离网风光发电系统的功率调节能力起到不可忽视的作用,但未充分考虑能量管理的综合性能。针对上述问题,提出了一种基于动态优化周期的改进能量管理策略。首先,以系统运行成本最小为目标进行日前优化。然后,在日内滚动优化的过程中自适应调节权重因子,合理协调短期功率平抑和长期状态优化,并对滚动优化周期进行动态调节,在减少冗余调节的同时,提升控制器的实时响应能力。最后,在实时校正层分别使用逐次变分模态分解和双层模糊控制对混合储能功率进行初次分配和二次分配,充分利用混合储能的运行特性并提升系统鲁棒性。算例分析表明,与传统策略相比,改进能量管理策略可使系统运行成本、能量失衡率和计算时间分别降低38.3%、63.1%和57.9%,提高了系统能量管理的经济性、可靠性和实时性。

磷酸铁锂储能预制舱火灾烟气扩散及温度变化规律

随着电化学储能的大规模应用,储能预制舱安全问题日益突出。对储能预制舱内不同热失控位置下的储能预制舱火灾差异进行研究,可以帮助设计更有效的监测和灭火系统,提升储能预制舱安全性能。因此,模拟研究不同热失控位置下储能预制舱火灾烟气扩散及温度变化规律具有重要意义。文中基于直接数值模拟和大涡模拟方法,依据实际储能预制舱尺寸构建磷酸铁锂储能预制舱的数值模型,引入更符合火情发展的t2模型,通过模拟不同热失控位置的火灾情境,研究储能预制舱内烟气扩散和温度变化规律。仿真结果表明,热失控的位置不同,烟气具有不同的动态行为,热失控位置越靠近底层,烟气运动越快,充满储能预制舱时间越短。当热失控位置靠近舱顶,在高度1.85 m以上的区域温度较高,并伴随显著的温度波动时,储能预制舱水平方向上的温度差显著增大。文中进一步分析额定容量为1.2 MW·h的标准储能预制舱的灭火系统设计方案,发现全氟己酮灭火系统在喷淋强度为20 L/(min·m2)、喷淋角度为120°、全氟己酮灭火剂粒径大小为50μm时,能有效控制火灾,减少火灾造成的损害。文中的研究成果可为储能预制舱内监测预警装置分布式布署策略及消防安全设计提供理论指导。