Dynamics Of Energy Exchange Research Articles

Dynamics, plant physiological and environmental controls of energy exchange in a grapevine greenhouse in Northeast China

The dynamics of latent heat flux (LE) in greenhouse agricultural production, an integral component of water and energy balance, are yet to be comprehensively understood. A four-year experiment (2017–2019, and 2021) was conducted in a solar greenhouse with grapevines to examine the patterns of energy and water vapor and their underlying mechanisms. The results indicated that LE was responsible for most of the net radiation (Rn), comprising 55.13–73.62 %. Sensible heat flux (H) accounted for 16.42–22.80 % of Rn, whereas the ratio of soil and wall heat flux to Rn was relatively minor, ranging from -7.3 % to 16.5 % during the four growing seasons. The order of LE/Rn in the different growth stages (I, II, and III) of grapevines was: II > III > I. The average value of Bowen ratio (β = H /LE) in the entire growth period was 0.34–0.44. The close relationship between β and leaf area index (LAI) demonstrated that LAI significantly influenced the energy distribution of the greenhouse, with a larger impact in stage I than in stages II and III (R2 at 0.19–0.50). The high values of the decoupling coefficient (0.69–0.82) and the Priestley–Taylor coefficient (α, 0.90–1.02) suggested that Rn was the main factor determining LE during the growing seasons. However, throughout stages I and III, LE was primarily influenced by vapor pressure deficit (VPD) and crop surface conductance (Gc), and the controlling effect of Rn on LE weakened. Gc was closely related to α (R2 = 0.59–0.90), suggesting that Gc significantly affected daily LE. In addition, changes in normalization of VPD by photosynthetically active radiation and LAI affected Gc, which in turn affected LE and energy distribution in the greenhouse. These findings are important for studying water vapor transport in greenhouses and for developing energy-driven models, that may improve water management for irrigation in greenhouses.

Effects of Revetments on Nitrification and Denitrification Potentials in the Urban River–Riparian Interface

River–riparian interfaces (RRIs) are not only an important type of urban land but also a key area for mitigating and controlling urban river nitrogen pollution. However, the material and energy exchange dynamics in the natural interaction between rivers and RRIs undergo changes due to the introduction of recently constructed revetments, affecting the nitrogen cycling of the RRI, and the impact of revetments on the control and mitigation of river nitrogen pollution in an RRI is unknown. Therefore, RRI soil properties, nitrification potentials (NPs), and denitrification potentials (DPs) were measured in natural, permeable, and impervious revetments in this study. Furthermore, structural equation models were developed to investigate the potential mechanism of the revetment’s impact on RRI NPs and DPs. The NPs of the natural revetment (NR) (7.22 mg/(kg·d)) were 2.20 and 2.16 times that of the impervious revetment (IR) and permeable revetments (PRs), respectively. The most important influencing factors of NPs were the aboveground biomass (AB) and available nitrogen. Similarly, the denitrification potential (DP) of the PR was 3.41 and 2.03 times that of the NR (22.44 mg/(kg·d)) followed by the IR (37.59 mg/(kg·d)). Furthermore, the AB had the greatest direct and total benefit on the DP, and nitrate may be a factor limiting the denitrification process. A revetment primarily disturbs the anaerobic environment and soil properties at RRIs, as well as changing the nitrification and denitrification potentials via soil erosion, solute exchange, and dry–wet alternation. These research results furnish a theoretical foundation for the restoration of urban rivers’ ecology and additionally provide benchmarks for sustainable development in urban areas.

Direct Numerical Simulation of Nonequilibrium Effects on Decaying Isotropic Turbulence

The Direct Numerical Simulation of decaying isotropic turbulence is performed with nonequilibrium effects. Oxygen is used as the test gas in the simulations. The individual and combined effects of vibrational relaxation and chemical reactions are studied by considering four different simulation cases. The time evolution of mean thermodynamic properties and turbulent statistics is analyzed. Budgets for turbulent kinetic energy and mean internal energy are computed to explain the dynamics of energy exchange associated with different nonequilibrium effects. The time evolution of enstrophy and turbulent length scales is also studied. The dissociation reaction is found to significantly affect the evolution of mean thermodynamic quantities as well as turbulence. Vibrational relaxation is found to significantly affect the flow in the presence of chemical reactions. The effects of changing the initial conditions on the resulting flowfield are analyzed.

Spatiotemporal distribution and impact factors of GNSS-PWV in China based on climate region

Water vapor plays a pivotal role in the intricate processes of energy exchange and climate dynamics. However, a comprehensive understanding of the spatial distribution and temporal variability of water vapor in distinct climatic regions of China is still limited due to the intricate interplay of complex topography and diverse climatic conditions. This study investigates the multiscale variability of water vapor using 10-year 1-hour data of precipitable water vapor (PWV) from 248 observation stations of the Crustal Movement Observation Network of China (CMONOC). Significant variations in PWV distribution among China's climate regions are observed. Average PWV values vary considerably across regions, with the Tropical and Subtropical Monsoon Climate (TSMC) having the highest mean PWV of 32.09 mm, followed by the Midlatitude Monsoon Climate (MMC) with 15.70 mm, the Humid Continental Climate (HCC) with 9.26 mm, and the Plateau Climate (PC) with 7.66 mm. Seasons exhibit summer concentration and winter reduction across regions. Most stations exhibit increasing PWV trends, while a few show decreasing trends. The amplitude of annual PWV variations is higher in TSMC and MMC regions with a range from 8 to 22 mm, compared to HCC and PC regions with a range from 2 to 15 mm. Semiannual variations range from 0 to 6 mm in each region. PWV negatively correlates with latitude, altitude and pressure, particularly in the TSMC. Positive correlations with temperature exist in all regions, with varying strengths. Thermodynamic factors primarily impact PWV, while dynamic factors have secondary influence, equally significant in the PC region.

Mixed quantum/classical theory (MQCT) approach to the dynamics of molecule-molecule collisions in complex systems.

We developed a general theoretical approach and a user-ready computer code that permit study of the dynamics of collisional energy transfer and ro-vibrational energy exchange in complex molecule-molecule collisions. The method is a mixture of classical and quantum mechanics. The internal ro-vibrational motion of collision partners is treated quantum mechanically using a time-dependent Schrödinger equation that captures many quantum phenomena including state quantization and zero-point energy, propensity and selection rules for state-to-state transitions, quantum symmetry and interference phenomena. A significant numerical speed up is obtained by describing the translational motion of collision partners classically, using the Ehrenfest mean-field trajectory approach. Within this framework a family of approximate methods for collision dynamics is developed. Several benchmark studies for diatomic and triatomic molecules, such as H2O and ND3 collided with He, H2 and D2, show that the results of MQCT are in good agreement with full-quantum calculations in a broad range of energies, especially at high collision energies where they become nearly identical to the full quantum results. Numerical efficiency of the method and massive parallelism of the MQCT code permit us to embrace some of the most complicated collisional systems ever studied, such as C6H6 + He, CH3COOH + He and H2O + H2O. Application of MQCT to the collisions of chiral molecules such as CH3CHCH2O + He, and to molecule-surface collisions is also possible and will be pursued in the future.

Full-scale ab initio simulations of laser-driven atomistic dynamics

The coupling of excited states and ionic dynamics is the basic and challenging point for the materials response at extreme conditions. In the laboratory, the intense laser produces transient nature and complexity with highly nonequilibrium states, making it extremely difficult and interesting for both experimental measurements and theoretical methods. With the inclusion of laser-excited states, we extend an ab initio method into the direct simulations of whole laser-driven microscopic dynamics from solid to liquid. We construct the framework of combining the electron-temperature-dependent deep neural-network potential energy surface with a hybrid atomistic-continuum approach, controlling non-adiabatic energy exchange and atomistic dynamics, which enables consistent interpretation of experimental data. By large-scale ab initio simulations, we demonstrate that the nonthermal effects introduced by hot electrons play a dominant role in modulating the lattice dynamics, thermodynamic pathway, and structural transformation. We highlight that the present work provides a path to realistic computational studies of laser-driven processes, thus bridging the gap between experiments and simulations.

Manipulating light–matter interaction into strong coupling regime for photon entanglement in plasmonic lattices

Enhancing light–matter interaction into the strong coupling regime attracts tremendous attention in both theory and experiment, which presents essential significance in research from nano-optics to quantum information. In this work, the entanglement effect is observed in the photons emitted from a plasmonic lattice as the coherent light–matter interaction occurs into the strong coupling regime with a Rabi splitting of 93.4 meV. A full quantum mechanical treatment based on the number state representation is established to reveal the underlying physics of the strong coupling phenomenon, especially the femtosecond dynamics of energy exchange and damping. The entangled split states display oscillating concurrence and negative Wigner quasiprobability distribution function, which demonstrates that this designed plasmonic lattice system can serve as an on-demand entangled photon source for quantum information.

Energy absorbancy and freezing-temperature tunability of NaCl solutions during ice formation

Freezing-thawing cycling of salt solutions is ubiquitously important to fields varying from biochemistry to agriculture, climate, and geological engineering. However, understanding the dynamics of energy exchange and freezing-temperature TN shift during phase transition of the concentrated solutions remains elusive despite intensive investigations since the discovery of Homeister series in 1888. Here we address this issue by focusing on the performance of the hydrogen bond (O:HO) in the fraction fS molecules of the hydrating supersolid phase and in the remaining fraction fO molecules of the pristine phase during NaCl solution ice formation. The supersolid formation is related to the effect of ionic polarization that shortens and stiffens the HO bond, while lengthening and weakening the O:H non-bonding interactions in the hydration cells. The supersolid phase is gel-like, less dense, viscoelastic, and mechanically and thermally stable. We demonstrate that the polarization-weakening of the O:H non-bonding interactions of the supersolid phase reduces the TN of the solution and that the HO cooling contraction in the quasisolid (QS) phase of the pristine water absorbs energy during the Liquid-QS-Ice transition of solution. At fS = 1, neither TN nor energy absorption is resolved within the range of 273 ± 20 K. The least saturation number of molecules is 10 per pair of Na+ and Cl− ions. These findings shall help to develop solutions with tunable TN for practical applications and to understand the mechanism of energy exchange during phase transition in the temperature and time domains.

Links between the complexities in atmospheric-soil energy exchange and temperature dynamics in tropical regions

In this work, the variations in the dynamical complexities in soil temperature variations were compared with that of air temperature using measured temperature parameters from different stations located in Nigeria. These parameters were also compared to the monthly averages of rainfall. The data sets were analysed using nonlinear time series analytical techniques. The results reveal that the annual trend of dynamical complexity follows a reverse trend of the rainfall peak period and the Lyapunov exponent for the un-detrended air temperature time series does not follow the same annual trend as that of the soil temperature. Also, dynamical properties of the two parameters are highly associated with correlation coefficients that are in some cases as high as 0.85 especially for the entropy measure for both air and soil. It was observed, however, that the degree of correlations between these parameters varies with time and location. An observed graduated response of Tsallis entropy computed for detrended soil temperature revealed a steady increase of the values of Tsallis entropy from north to south of Nigeria across the geographical belts. The observed variations have been associated with varying atmospheric factors and the changes in the properties of the soil with location. These factors might be influential in conjunction with other factors in the air-soil interface.

Energy exchange in globally coupled mechanical phase oscillators

We study the stationary dynamics of energy exchange in an ensemble of phase oscillators, coupled through a mean-field mechanical interaction and added with friction and an external periodic excitation. The degree of entrainment between different parts of the ensemble and the external forcing determines three dynamical regimes, each of them characterized by specific rates of energy exchange. Using suitable approximations, we are able to obtain analytical expressions for those rates, which are in satisfactory agreement with results from numerical integration of the equations of motion. In some of the dynamical regimes, the rates of energy exchange show nontrivial dependence on the friction coefficients-in particular, nonmonotonic behavior and sign switching. This suggests that, even in this kind of stylized model, power transfer between different parts of the ensemble and to the environment can be manipulated by a convenient choice of the individual oscillator parameters.

Dynamics and environmental controls of energy exchange and evapotranspiration in a hilly tea plantation, China

Tea plantations (Camellia sinensis) are expanding rapidly in China during the last two decades. However, the detailed knowledges of water vapor and energy fluxes in tea plantation ecosystem are still absent. In this study, we explored the temporal variation in water vapor and energy fluxes over a tea plantation through the analysis of 4-year (2014–2017) fluxes data obtained via the eddy covariance technique. The results showed that latent heat flux (LE) was the main consumer of net radiation (Rn). LE/Rn ranged from 0.50 to 0.67 at the pruning period (April-June) and dormant period (December-March). At the mid-growing season (July-September) and late growing season (October-November), LE accounted for more than 0.75 of Rn, except for the mid-growing season in 2016. Sensible heat flux (H) showed an almost opposite trend to LE, while seasonal variation of soil heat flux (G) was small. The interannual actual evapotranspiration (ETa) was stable in tea plantation ranging from 694–741 mm (CV = 2.9 %) despite a large interannual variation in precipitation (CV = 23.9 %). The average annual ETa accounted for 49 % of the corresponding annual precipitation. The highest measured daily ETa reached 5.2–6.9 mm in July for both years. The seasonal variations of daily ETa were strongly related to the Rn. At the mid-growing and late growing seasons, Rn was the limiting factor on ETa with high Priestley-Taylor coefficient (α, 1.05) and decoupling coefficient (Ω, 0.69). In addition, low temperature physiological dormancy and vapor pressure deficit (VPD) at the dormant period and pruning of canopy at the pruning period leading low leaf area index (LAI) also played secondary impacts on ETa through their eff ;ects on canopy surface conductance (< 10 mm s−1). Moreover, ETa would be significantly affected by soil water availability at the mid-growing season due to the large water demand for growth, when the soil water was below 0.12 m3 m−3.

Energy partitioning and evapotranspiration over a rotated paddy field in Southern China

There have been recent significant changes in crop rotation and irrigation methods in paddy fields in southern China. Examining the dynamics of energy exchange and evapotranspiration (ET) in rotated paddy fields is important for better understanding of land surface processes affected by human activities. In the present study, energy fluxes, including net radiation (Rn), latent heat flux (LE), sensible heat flux (H) and soil heat flux (G) were investigated using two years (2016–2017) eddy covariance measurements from a rotated paddy field in southern China. The results showed that LE was the main consumer of Rn. Seasonal LE/Rn varied from 0.77 to 0.86 for the rice seasons, and from 0.48 to 0.51 for the milk vetch and fallow seasons. H showed an opposite seasonal trend with LE. G was higher during the milk vetch and fallow seasons because of the greater coverage of exposed soil. The high Priestley-Taylor coefficient (α, 1.11 ± 0.16) and decoupling factor (Ω, 0.71 ± 0.15) corroborated the energy-limited conditions for the rotated paddy field, indicating that Rn was the main meteorological factor governing ET. Canopy conductance (Gc) was closely related to α, suggesting that daily ET was significantly affected by Gc. Vapor pressure deficit (VPD), photosynthetically active radiation (PAR) and leaf area index (LAI) played secondary roles in daily ET through their effects on Gc. ET was also affected by the wet and dry conditions of the paddy field. ET was slightly enhanced under dry conditions when LAI was low, while it decreased when LAI was large.

HydroShoot: a functional-structural plant model for simulating hydraulic structure, gas and energy exchange dynamics of complex plant canopies under water deficit—application to grapevine (Vitis vinifera)

AbstractThis paper presents HydroShoot, a leaf-based functional-structural plant model (FSPM) that simulates gas exchange rates of complex plant canopies under water deficit conditions. HydroShoot is built assuming that simulating both the hydraulic structure of the shoot together with the energy budget of individual leaves is the asset for successfully scaling-up leaf to canopy gas exchange rates. HydroShoot includes three interacting modules: hydraulic, which calculates the distribution of xylem water potential across shoot hydraulic segments; energy, which calculates the complete energy budget of individual leaves; and exchange, which calculates net carbon assimilation and transpiration rates of individual leaves. HydroShoot was evaluated on virtual and real grapevines having strongly contrasted canopies, under well-watered and water deficit conditions. It captured accurately the impact of canopy architecture and soil water status on plant-scale gas exchange rates and leaf-scale temperature and water potential. Both shoot hydraulic structure and leaf energy budget simulations were, as postulated, required to adequately scaling-up leaf to canopy gas exchange rates. Notwithstanding, simulating shoot hydraulic structure was found more necessary to adequately performing this scaling task than simulating leaf energy budget. That is, the intra-canopy variability of leaf water potential was a better predictor of the reduction of whole plant gas exchange rates under water deficit than the intra-canopy variability of leaf temperature. We conclude that simulating the shoot hydraulic structure is a prerequisite if FSPMs are to be used to assess gas exchange rates of complex plant canopies as those of grapevines. Finally, HydroShoot is available through the OpenAlea platform (https://github.com/openalea/hydroshoot) as a set of reusable modules.

Energy Exchange Dynamics and Relaxation of Excitations upon Strong Exciton–Plasmon Interaction in a Planar Nanostructure of Molecular J-Aggregates on a Metal Substrate

The kinetics of energy exchange between the plasmonic and excitonic subsystems in a “metal–dielectric–molecular layer” is studied for a planar composite nanostructure with a strong exciton–plasmon interaction. It is shown that the time dependence of the energy transfer between the components of the system has the character of damped oscillations, which depend on the prepared initial state, a number of relaxation parameters, the Rabi frequency, and the detuning from resonance.

Non-tuned data intelligent model for soil temperature estimation: A new approach

In knowledge-based decision-support systems, soil temperature (ST) estimation can be considered as the core modeling task used for investigating the dynamics of solar energy exchange between the land surface and the sub-surface soil layers. In addition, the impacts of meteorological processes on energy uptake into the underlying soils and the design of more resilient and sustainable agricultural systems for improved crop health and resource management. In this paper, monthly ST estimation at various soil depths (i.e., 5, 50 and 100 cm) is performed by applying data-intelligent machine learning models: extreme learning machine (ELM), artificial neural network (ANN) and M5 Model Tree (M5 Tree). The predictive models are trained using meteorological information from two stations (i.e., Mersin and Adana, Turkey). The models are constructed using monthly input variables, including air temperature (T-air), windspeed (W), relative humidity (RH), solar radiation (SR), while the objective variable is the soil temperature measurement at 5, 50 and 100 cm depths for the period 1986–2010. Multi-objective performance criteria are applied to diagnose the predictive accuracy of the data-intelligent models, entailing the correlation coefficient (R), root mean square error (RMSE), mean absolute error (MAE), Willmott's Index (WI), Nash Sutcliffe's coefficient (Nash) and the Legates & McCabe's Index (LMI). Based on the tested dataset, the ELM model is yielded the most accurate performance for Mersin station compared to the lower performance of ANN and M5 Tree models. For this case, the most accurate performance is attained for the ST estimation at a depth of 50 cm, with the highest value of R = 0.992, WI = 0.999, Nash = 0.981, LMI = 0.879 and the lowest value of the relative RMSE and MAE values (i.e., 4.7 and 4.0%, respectively), attained using T-air, W, RH and periodicity as the predictor variables. The performance results for the Adana station behave differently, where ELM is seen to exceed the ANN and M5 Tree models for ST estimation at the depths of 5 and 100 cm. On the other hand, the ANN model performs marginally better than the ELM and the M5 Tree model at a depth of 50 cm with a different set of input combinations. The assessment of the estimation skills reveals the efficacy of the ELM over the counterpart benchmark models. In accordance with the present results, it is concluded that ELM model can be applied as an ideal decision-support tool for soil temperature estimation at multiple depths, whilst ensuring that an appropriate combination of meteorological inputs is applied to yield an optimal model.

Carbon, water and energy exchange dynamics of a young pine plantation forest during the initial fourteen years of growth

Abstract This study presents the energy, water, and carbon (C) flux dynamics of a young afforested temperate white pine (Pinus strobus L.) forest in southern Ontario, Canada during the initial fourteen years (2003–2016) of establishment. Energy fluxes, namely, net radiation (Rn), latent heat (LE), and sensible heat (H) flux increased over time, due to canopy development. Annual values of ground heat flux (G) peaked in 2007 and then gradually declined in response to canopy closure. The forest became a consistent C-sink only 5 years after establishment owing in part to low respiratory fluxes from the former agricultural, sandy soils with low residual soil organic matter. Mean annual values of gross ecosystem productivity (GEP), ecosystem respiration (RE), and net ecosystem productivity (NEP) ranged from 494 to 1913, 515 to 1774 and −126 to 216 g C m−2 year−1 respectively, over the study period. Annual evapotranspiration (ET) values ranged from 328 to 429 mm year−1 over the same period. Water use efficiency (WUE) increased with stand age with a mean WUE value of 3.92 g C kg−1 H2O from 2008 to 2016. Multivariable linear regression analysis conducted using observed data suggested that the overall, C and water dynamics of the stand were primarily driven by radiation and temperature, both of which explained 77%, 48%, 28%, and 76% of the variability in GEP, RE, NEP, and ET, respectively. However, late summer droughts, which were prevalent in the region, reduced NEP. The reduction in NEP was enhanced when summer drought events were accompanied by increased heat such as those in 2005, 2012 and 2016. This study contributes to our understanding of the energy, water and C dynamics of afforested temperate conifer plantations and how these forests may respond to changing climate conditions during the crucial initial stage of their life cycle. Our findings also demonstrate the potential of pine plantation stands to sequester atmospheric CO2 in eastern North America.

Topological Aharonov-Bohm suppression of optical tunneling in twisted nonlinear multicore fibers

We show that the Aharonov-Bohm-like suppression of optical tunneling in twisted multicore fibers can persist even under highly nonlinear conditions. Our analysis indicates that the topological phase is robust and remains intact in the presence of nonlinearity. The energy exchange dynamics are analyzed theoretically via closed-form solutions in four-core ring systems. Effects arising from asymmetry are also investigated. A possible arrangement to experimentally observe this effect is suggested.

Energy exchange dynamics across L–H transitions in NSTX

We studied the energy exchange dynamics across the low-to-high-confinement (L–H) transition in NSTX discharges using the gas-puff imaging (GPI) diagnostic. The investigation focused on the energy exchange between flows and turbulence to help clarify the mechanism of the L–H transition. We applied this study to three types of heating schemes, including a total of 17 shots from the NSTX 2010 campaign run. Results show that the edge fluctuation characteristics (fluctuation levels, radial and poloidal correlation lengths) measured using GPI do not vary just prior to the H-mode transition, but change after the transition. Using a velocimetry approach (orthogonal-dynamics programming), velocity fields of a cm GPI view during the L–H transition were obtained with good spatial (∼1 cm) and temporal (∼2.5 μs) resolutions. Analysis using these velocity fields shows that the production term is systematically negative just prior to the L–H transition, indicating a transfer from mean flows to turbulence, which is inconsistent with the predator–prey paradigm. Moreover, the inferred absolute value of the production term is two orders of magnitude too small to explain the observed rapid L–H transition. These discrepancies are further reinforced by consideration of the ratio between the kinetic energy in the mean flow to the thermal free energy, which is estimated to be much less than 1, suggesting again that the turbulence depletion mechanism may not play an important role in the transition to the H-mode. Although the Reynolds work therefore appears to be too small to directly deplete the turbulent free energy reservoir, order-of-magnitude analysis shows that the Reynolds stress may still make a non-negligible contribution to the observed poloidal flows.

Dynamics and biophysical controls of carbon, water and energy exchange over a semiarid shrubland in northern China

Dynamics and biophysical controls of carbon, water and energy exchange over a semiarid shrubland in northern China

Dynamics of water vapor and energy exchanges above two contrasting Sudanian climate ecosystems in Northern Benin (West Africa)

AbstractNatural ecosystems in sub‐Saharan Africa are experiencing intense changes that will probably modify land surface feedbacks and consequently the regional climate. In this study, we have analyzed water vapor (QLE) and sensible heat (QH) fluxes over a woodland (Bellefoungou, BE) and a cultivated area (Nalohou, NA) in the Sudanian climate of Northern Benin, using 2 years (from July 2008 to June 2010) of eddy covariance measurements. The evaporative fraction (EF) response to environmental and surface variables was investigated at seasonal scale. Soil moisture was found to be the main environmental factor controlling energy partitioning. During the wet seasons, EF was rather stable with an average of 0.75 ± 0.07 over the woodland and 0.70 ± 0.025 over the cultivated area. This means that 70–75% of the available energy was changed into actual evapotranspiration during the investigated wet seasons depending on the vegetation type. The cumulative annual actual evapotranspiration (AET) varied between 730 ± 50 mm yr−1 at the NA site and 1040 ± 70 mm yr−1 at the BE site. With similar weather conditions at the two sites, the BE site showed 30% higher AET values than the NA site. The sensible heat flux QH at the cultivated site was always higher than that of the woodland site, but observed differences were much less than those of QLE. In a land surface conversion context, these differences are expected to impact both atmospheric dynamics and the hydrological cycle.