Transient Storage Research Articles

Influence of Energy Storage on System Transient Stability Based on SGEAC Analysis

In order to prevent the system from being paralyzed in a large area after being disturbed, it is particularly important to compensate the energy of the unstable area after being disturbed. Firstly, the quantitative integral of transient margin considering energy storage system is derived based on SGEAC method. Secondly, according to the approximate sensitivity of line transient margin, the storage position is determined. Finally, PSASP/UD module is used to build the transient energy storage battery model, and CEPRI-36 node system is used for a large number of simulations. The simulation results show that the energy storage system can inhibit the acceleration of power angle, improve the system transient stability margin, and play a positive role in improving the system transient stability.

Transient Storage Model Parameter Optimization Using the Simulated Annealing Method

AbstractHyporheic exchange in streams is critical to ecosystem functions such as nutrient cycling along river corridors, especially for slowly moving or small stream systems. The transient storage model (TSM) has been widely used for modeling of hyporheic exchange. TSM calibration, for hyporheic exchange, is typically used to estimate four parameters, including the mass exchange rate coefficient, the dispersion coefficient, stream cross‐sectional area, and hyporheic zone cross‐sectional area. Prior studies have raised concerns regarding the non‐uniqueness of the inverse problem for the TSM, that is, the occurrence of different parameter vectors resulting in TSM solution that reproduces the observed in‐stream tracer break through curve (BTC) with the same error. This leads to practical non‐identifiability in determining the unknown parameter vector values even when global‐optimal values exist, and the parameter optimization becomes practically non‐unique. To address this problem, we applied the simulated annealing method to calibrate the TSM to BTCs, because it is less susceptible to local minima‐induced non‐identifiability. A hypothetical (or synthetic) tracer test data set with known parameters was developed to demonstrate the capability of the simulated annealing method to find the global minimum parameter vector, and it identified the “hypothetically‐true” global minimum parameter vector even with input data that were modified with up to 10% noise without increasing the number of iterations required for convergence. The simulated annealing TSM was then calibrated using two in‐stream tracer tests conducted in East Fork Poplar Creek, Tennessee. Simulated annealing was determined to be appropriate for quantifying the TSM parameter vector because of its search capability for the global minimum parameter vector.

Combining Flood Risk Mitigation and Carbon Sequestration to Optimize Sustainable Land Management Schemes: Experiences from the Middle-Section of Hungary’s Tisza River

The record floods experienced along the Tisza River between 1998 and 2001 brought a paradigm shift in infrastructural solutions for flood protection. A flood peak polder system was built for transient water storage without any substantial change in land use in the polders, despite the potential to do so under the new scheme. The recent improvement of quantified flood risk assessment methodologies and stronger foundations for the valuation of carbon sequestration benefits now provide more information on the magnitude of missed opportunities and the potential for comprehensive land use and flood risk management solutions. This paper evaluates and combines the results of three cost-benefit type analyses on the conflicting relations of pursuing flood risk mitigation and land management goals. Although the studies were conducted at different locations of the same river stretch, they are all inspected using the same flood waves. Results assert that as EU-CAP agricultural subsidies stabilize individual benefits from arable land use in the short-run, public benefits and long-term individual benefits fail to reach their potential value. The combined analysis of flood risk change and CO2 sequestration provides the economic rationale for the ecological revitalization along rivers with flood peak polders, helping to solve the conflict between hydrological and ecological objectives in floodplains. Capitalizing the value of the community benefits of forests in terms of CO2 sequestration is limited by the unresolved property rights allocation of this natural capacity between landowners and the state, the latter being responsible for fulfilling international CO2 reduction agreements; this uncertain legal background is an obstacle to the creation of sustainable economic conditions for the development and expansion of beneficial land management processes along rivers.

Nutrient retention in agricultural headwater stream: artificial manipulation of main-channel morphology and hydrologic condition.

To make up for the deficiency of transient storage and nutrient retention capacity of some headwater streams, some effective artificial measures have been developed to improve the stream ecosystem functions. But few studies have focused on the effects of artificial manipulation on nutrient retention in hydrologic and non-hydrologic processes of streams. In response, we selected an agricultural headwater stream in the Banqiao River tributary of Chaohu Lake Basin, artificially altered the flow pattern in the main-channel by introducing barriers which were composed of soil, coarse sand, and stones, and used the tracer experiment and OTIS (one-dimensional transport with inflow and storage) model to assess the transient storage potential of stream and the nutrient retention of hydrologic and non-hydrologic processes. Compared with the control, the retention capacity of ammonium (NH4+) and phosphate (PO43-) and the transient storage potential were increased after introducing barriers. In addition, the total retention (TR), hydrologic retention (HR), and non-hydrologic retention (NHR) of NH4+ and PO43- were significantly increased after manipulation.

Machine learning-based prediction of transient latent heat thermal storage in finned enclosures using group method of data handling approach: A numerical simulation

This paper presents the numerical simulations and machine learning-based prediction of the transient melting process of phase change material (PCM) in latent heat thermal storage (LHTS) units. The storage units are rectangular enclosures equipped with fins of different heights and numbers. For all enclosures, the volume of fins and PCM are kept constant. Melting processes of PCM in different storage units are simulated using computational fluid dynamics (CFD) to determine the impacts of fin parameters on the thermal behavior of the LHTS unit. Transient variation of liquid fraction and stored energy in the different storage units are obtained. Then, the group method of data handling (GMDH) type of artificial neural networks (ANNs) is employed and trained through numerical findings to develop correlations for predicting the instantaneous liquid fractions and stored energy in the finned enclosures. To evaluate the effectiveness of the prediction model, mean square, root mean square, and standard deviation errors as well as correlation coefficient have been calculated and proved the accuracy of the proposed correlations.

Graphs of Hydrogen-Bond Networks to Dissect Protein Conformational Dynamics.

Dynamic hydrogen bonds and hydrogen-bond networks are ubiquitous in proteins and protein complexes. Functional roles that have been assigned to hydrogen-bond networks include structural plasticity for protein function, allosteric conformational coupling, long-distance proton transfers, and transient storage of protons. Advances in structural biology provide invaluable insights into architectures of large proteins and protein complexes of direct interest to human physiology and disease, including G Protein Coupled Receptors (GPCRs) and the SARS-Covid-19 spike protein S, and give rise to the challenge of how to identify those interactions that are more likely to govern protein dynamics. This Perspective discusses applications of graph-based algorithms to dissect dynamical hydrogen-bond networks of protein complexes, with illustrations for GPCRs and spike protein S. H-bond graphs provide an overview of sites in GPCR structures where hydrogen-bond dynamics would be required to assemble longer-distance networks between functionally important motifs. In the case of spike protein S, graphs identify regions of the protein where hydrogen bonds rearrange during the reaction cycle and where local hydrogen-bond networks likely change in a virus variant of concern.

Transient storage and nitrogen retention in headwater stream of a suburban watershed in Beijing, China

Transient storage refers to a vital process affecting nutrient retention dynamics. To explore how streambed topography, discharge, and nutrient ambient concentration impact the transient storage and nitrogen retention of the headwater stream, tracer experiments were performed in five reaches of the Yanqi watershed. The one-dimensional transport with inflow and storage model (OTIS) was employed to simulate the solute injection. Transient storage potential was evaluated by transient storage metrics. Moreover, the material balance method was adopted to obtain the amount of nitrogen retention in the respective reach, and the nutrient spiraling metrics were determined to assess the nitrogen retention potential. As revealed from this study, improving transient storage under low flow conditions effectively facilitated nitrogen retention (except for the case of low-head weirs reach), while the erosion of high discharge destroyed the transient storage zone, thereby reducing the nitrogen retention potential. Ecological restoration in the Yanqi watershed could rescue nitrogen retention potential to a natural state under low flow, whereas limitations were identified in nitrogen retention potential under high flow and high ambient concentration.

Surrogate prediction of the breakthrough curve of solute transport in rivers using its reach length dependence

Techniques for predicting the contaminant cloud propagation along a stream are necessary for swift action against contaminant spill accidents in fluvial systems. Due to their low computational cost, one-dimensional solute transport models have conventionally been employed, in which the complex channel characteristics are considered using model parameters. However, the determination of such parameters relies predominantly on optimization techniques based on pre-measured tracer data, which are usually unavailable for unexpected accidents. The present paper suggests an alternative method for predicting a breakthrough curve (BTC) variation along an unmeasured stream reach where no flow information is provided. In this study, we investigated the relationship between directly-measured flow properties and BTC characteristics based on field tracer experiments. Using statistical features of the tracer BTCs, we devised a regressive prediction method for estimating the BTC features as a function of travel distance, and validated the method by comparison with simulations using both a one-dimensional advection–dispersion equation (ADE) and transient storage model (TSM), whose parameters were calibrated at upstream reaches. The proposed regressive predictions were relatively accurate than those from parameter-calibrated models, and this advantage was more apparent for long-distance predictions for the unmeasured river reach.

Relationships Among Temporal Fine Structure Sensitivity, Transient Storage Capacity, and Ultra-High Frequency Hearing Thresholds in Tinnitus Patients and Normal Adults of Different Ages.

BackgroundElderlies and tinnitus patients often find it challenging to process acoustic signals in noisy environments. The sensitivity to temporal fine structure (TFS), the transient storage capacity for TFS, and the ultra-high frequency (UHF) thresholds are all associated with aging-related damage, evidenced by speech-in-noise perception deficits. In the present study, we aimed to investigate the relationships among TFS sensitivity, transient storage capacity, and UHF thresholds in tinnitus patients and normal adults of different ages.MethodsIn the present study, 38 tinnitus patients (age ranging from 21 to 65) and 23 non-tinnitus adults (age ranging from 22 to 56) were enrolled, and some of their auditory indicators were examined, including the TFS-adaptive frequency (TFS-AF), break in interaural correlation (BIAC) delay threshold, and UHF thresholds.ResultsWe found no significant difference in TFS-AF thresholds and BIAC delay thresholds between the tinnitus group and normal group, while their relationships with age were more evident in the tinnitus group. Moreover, these two tests were only significantly correlated in the tinnitus group. UHF thresholds were significantly correlated with TFS-AF thresholds only in the tinnitus group, suggesting that the UHF hearing was positively associated with the TFS sensitivity.ConclusionThese findings indicated that the influencing factors, such as tinnitus and UHF thresholds, should be fully considered when examining age-related hearing decline, because the combination of tinnitus and poor UHF hearing might play a role in affecting hearing ability, such as TFS sensitivity.

Conservative solute transport processes and associated transient storage mechanisms: Comparing streams with contrasting channel morphologies, land use and land cover

AbstractLand use within a watershed impacts stream channel morphology and hydrology and, therefore, in‐stream solute transport processes and associated transient storage mechanisms. This study evaluated transport processes in two contrasting stream sites where channel morphology was influenced by the surrounding land use, land cover, climate and geologic controls: Como Creek, CO, a relatively undisturbed, high gradient, forested stream with a gravel bed and complex channel morphology, and Clear Creek, IA, an incised, low‐gradient stream with low‐permeability substrate draining an agricultural landscape. We performed conservative stream tracer injections at these sites to address the following questions: (1) How does solute transport vary between streams with differing morphologies? and (2) How does solute transport at each stream site change as a function of discharge? We analysed in‐stream tracer time series data and compared results quantifying solute attenuation in surface and subsurface transient storage zones. Significant trends were observed in these metrics with varying discharge conditions at the forested site but not at the agricultural site. There was a broad range of transport mechanisms and evidence of substantial exchange with both surface and hyporheic transient storage in the relatively undisturbed, forested stream. Changing discharge conditions activated or deactivated different solute transport mechanisms in the forested site and greatly impacted advective travel time. Conversely in the simplified agricultural stream, there was a narrow range of solute transport behaviour across flows and predominantly surface transient storage at all measured discharge conditions. These results demonstrate how channel simplification inhibits available solute transport mechanisms across varying discharge conditions.

Traditional Martial Arts and Shooting Training Have Different Effects on Auditory Fine Structure Processing Ability - Evidence from Behavioral Tests and fMRI

In this work, we explore the influence of traditional martial arts and shooting training on the ability of auditory Temporal Fine Structure (TFS) processing. Twenty-five college students participated in the experiment, including 8 traditional martial arts practitioners, 8 high-level shooting athletes, and 9 control groups without any regular exercise habits. The BIC (break in interaural correlation) delay threshold and TFS1 test were used to evaluate the transient storage capacity and sensitivity of TFS, respectively. An fMRI test was performed after the behavioral tests. The results found that the traditional martial arts group had stronger TFS sensitivity, while the shooting group had stronger TFS storage capacity and the performance of the behavioral tests of the shooting group is related to the fALFF value of the brain areas of interest. The effects of exercise training on hearing ability may have a specific neural basis and can be used for early intervention in potential hearing impairment.

Transient energy storage in phase change materials, development and simulation of a new TRNSYS component

In this paper, a mathematical model is developed for the simulation of encapsulated phase change material as a thermal energy storage tank. The model is modified for the TRNSYS software to enable researchers for investigating the performance of a latent heat energy store system integrated with solar energy systems and buildings. The model is validated against experimental and numerical studies and the error is found to be less than 2% and 10% for 1-D and 2-D models, respectively. The new component is applied for solar energy storage and it is concluded that it effectively follows the variation of solar irradiation. The application of a PCM tank for daily energy storage reduces the cooling and heating loads by 22.5% and 18%, respectively. The energy-saving with seasonal cooling storage using a PCM tank is about 7% of the total energy consumption.

Fecal Microbiota Transplants for Inflammatory Bowel Disease Treatment: Synthetic- and Engineered Communities-Based Microbiota Transplants Are the Future.

The human intestine harbors a huge number of diverse microorganisms where a variety of complex interactions take place between the microbes as well as the host and gut microbiota. Significant long-term variations in the gut microbiota (dysbiosis) have been associated with a variety of health conditions including inflammatory bowel disease (IBD). Conventional fecal microbiota transplantations (FMTs) have been utilized to treat IBD and have been proved promising. However, various limitations such as transient results, pathogen transfer, storage, and reproducibility render conventional FMT less safe and less sustainable. Defined synthetic microbial communities (SynCom) have been used to dissect the host-microbiota-associated functions using gnotobiotic animals or in vitro cell models. This review focuses on the potential use of SynCom in IBD and its advantages and relative safety over conventional FMT. Additionally, this review reinforces how various technological advances could be combined with SynCom to have a better understanding of the complex microbial interactions in various gut inflammatory diseases including IBD. Some technological advances including the availability of a gut-on-a-chip system, intestinal organoids, ex vivo intestinal cultures, AI-based refining of the microbiome structural and functional data, and multiomic approaches may help in making more practical in vitro models of the human host. Additionally, an increase in the cultured diversity from gut microbiota and the availability of their genomic information would further make the design and utilization of SynCom more feasible. Taken together, the combined use of the available knowledge of the gut microbiota in health and disease and recent technological advances and the development of defined SynCom seem to be a promising, safe, and sustainable alternative to conventional FMT in treating IBD.

Improved Melting of Latent Heat Storage Using Fin Arrays with Non-Uniform Dimensions and Distinct Patterns.

Employing phase-change materials (PCM) is considered a very efficient and cost-effective option for addressing the mismatch between the energy supply and the demand. The high storage density, little temperature degradation, and ease of material processing register the PCM as a key candidate for the thermal energy storage system. However, the sluggish response rates during their melting and solidification processes limit their applications and consequently require the inclusion of heat transfer enhancers. This research aims to investigate the potential enhancement of circular fins on intensifying the PCM thermal response in a vertical triple-tube casing. Fin arrays of non-uniform dimensions and distinct distribution patterns were designed and investigated to determine the impact of modifying the fin geometric characteristics and distribution patterns in various spatial zones of the heat exchanger. Parametric analysis on the various fin structures under consideration was carried out to determine the most optimal fin structure from the perspective of the transient melting evolution and heat storage rates while maintaining the same design limitations of fin material and volume usage. The results revealed that changing the fin dimensions with the heat-flow direction results in a faster charging rate, a higher storage rate, and a more uniform temperature distribution when compared to a uniform fin size. The time required to fully charge the storage system (fully melting of the PCM) was found to be reduced by up to 10.4%, and the heat storage rate can be improved by up to 9.3% compared to the reference case of uniform fin sizes within the same fin volume limitations.

The Fly Blood-Brain Barrier Fights Against Nutritional Stress.

In the wild, animals face different challenges including multiple events of food scarcity. How they overcome these conditions is essential for survival. Thus, adaptation mechanisms evolved to allow the development and survival of an organism during nutrient restriction periods. Given the high energy demand of the nervous system, the molecular mechanisms of adaptation to malnutrition are of great relevance to fuel the brain. The blood-brain barrier (BBB) is the interface between the central nervous system (CNS) and the circulatory system. The BBB mediates the transport of macromolecules in and out of the CNS, and therefore, it can buffer changes in nutrient availability. In this review, we collect the current evidence using the fruit fly, Drosophila melanogaster, as a model of the role of the BBB in the adaptation to starvation. We discuss the role of the Drosophila BBB during nutrient deprivation as a potential sensor for circulating nutrients, and transient nutrient storage as a regulator of the CNS neurogenic niche.

Surface Transient Storage Under Low‐Flow Conditions in Streams With Rough Bathymetry

AbstractIn natural and restored rivers, protruding river‐bed elements can cause complex flow patterns. We hypothesize that, particularly at very low flows, solute spreading in such streams is controlled by different mechanisms than at high flows, questioning existing parameterizations. We investigate two‐dimensional flow and transport in a synthetic channel with rough bathymetry under low‐flow conditions with a numerical model solving the full shallow‐water equations. Recirculation cells form behind protruding bed elements and trap water, macroscopically acting as transient‐storage domain. We fit the one‐dimensional mobile‐immobile transport model to the concentration breakthrough curves of the two‐dimensional model and relate the fitted parameters to easy‐to‐measure properties of the stream. The velocity in the mobile domain undergoes a power‐law relation with the discharge and the channel slope, differing from the relationship expected for normal flow in streams with large water depths. Both the fitted dispersion coefficient and the mass‐transfer coefficient between the mobile and immobile domains scale linearly with the velocity in the mobile domain. The ratio of immobile to mobile storage volumes β first increases then decreases with increasing discharge. We suggest measuring the surface area of bed elements protruding the water surface and that of the open water. The product of the corresponding area ratio with the velocity exerts a power‐law control on β. Altogether, we can relate the coefficients of the mobile‐immobile transport model to a few easy‐to‐measure properties of the stream. The findings of the present work contribute to the understanding of surface transient storage in natural and restored streams.

Partition of Rare Earth Elements Between Sulfate Salts Formed by the Evaporation of Acid Mine Drainage

Acid mine drainage (AMD) contains rare earth element (REE) concentrations several orders of magnitude higher than those of the rest of natural waters and could be a secondary source of REEs. In arid to semiarid climates with a long dry season, the precipitation of efflorescent sulfates constitutes a transient storage of REEs. The REE partition among the Al–Fe–Mg–Ca sulfates formed by the evaporation to dryness of six different AMDs was investigated by statistical methods and by selective dissolution. The chemical composition of the evaporitic salts showed that only three principal components (PCs) could explain more than 80% of the variability in the six samples analyzed. PC1 was associated with Ca and light REEs and interpreted as gypsum, whereas PC2 was associated with Y and heavy REEs, which were not clearly associated with a major sulfate. Finally, PC3 included Mg, Fe and several transition metals (Cu, Ni, Co, Mn and Zn) and was interpreted as Fe(II)-Mg sulfates. Selective dissolution of the salt mixtures with solutions saturated in the major sulfates revealed that the REEs were only retained in gypsum and were practically absent from the rest of the sulfates. The incorporation of REEs into gypsum decreased from Pr-Nd to La and Lu and was strictly ruled by the differences in their atomic radii and that of Ca in eight-fold coordination. However, gypsum concentrated less than 20% of the REE inventory (< 1% for Sc); the rest probably formed one or more unidentified trace minerals. This indicates that gypsum may not be an efficient way to concentrate REEs from AMD.

Impact of Sediment Layer on Longitudinal Dispersion in Sewer Systems

Experiments focused on pollution transport and dispersion phenomena in conditions of low flow (low water depth and velocities) in sewers with bed sediment and deposits are presented. Such conditions occur very often in sewer pipes during dry weather flows. Experiments were performed in laboratory conditions. To simulate real hydraulic conditions in sewer pipes, sand of fraction 0.6–1.2 mm was placed on the bottom of the pipe. In total, we performed 23 experiments with 4 different thicknesses of sand sediment layers. The first scenario is without sediment, the second is with sediment filling 3.4% of the pipe diameter (sediment layer thickness = 8.5 mm), the third scenario represents sediment filling 10% of the pipe diameter (sediment layer thickness = 25 mm) and sediment fills 14% of the pipe diameter (sediment layer thickness = 35 mm) in the last scenario. For each thickness of the sediment layer, a set of tracer experiments with different flow rates was performed. The discharge ranges were from (0.14–2.5)·10−3 m3·s−1, corresponding to the range of Reynolds number 500–18,000. Results show that in the hydraulic conditions of a circular sewer pipe with the occurrence of sediment and deposits, the value of the longitudinal dispersion coefficient Dx decreases almost linearly with decrease of the flow rate (also with Reynolds number) to a certain limit (inflexion point), which is individual for each particular sediment thickness. Below this limit the value of the dispersion coefficient starts to rise again, together with increasing asymmetricity of the concentration distribution in time, caused by transient (dead) storage zones.

Thermal performance of two enclosed rooms with different phase change materials under different weather conditions

In most of either space heating or space cooling applications, heat absorbed by the enclosing walls plays an important role. Phase change materials (PCMs) can either absorb or give out the absorbed latent heat energy. Latent heat absorption depends on the operating temperature and pressure conditions. In the present study, feasibility of different PCMs as building facades or walls for a single room in different climatic regions is investigated; two different room dimensions were chosen – shallow and tall. Heat transfer inside the buildings significantly depends on the shape / size of the walls. The modeling and simulations have been carried out using the Energyplus tool. Various built-in algorithms were used to solve for transient latent heat storage in PCM, conduction, convection, and radiation heat fluxes. PCMs were found to perform better lowering the room temperature in hot-arid and warm tropic regions. On the other hand, in extreme cold weather conditions, the considered PCMs were found to maintain relatively higher room temperatures and was chiefly due to thermal inertia of PCM in solid phase. The room air temperature attainment with and without various PCMs as building façade material or walls have been discussed and compared for shallow and tall room dimensions under different weather conditions.

Capacity factor characteristics for a multi‐tubular sensible energy storage system with wire coil inserts

The transient energy storage in a sensible energy storage system (SESS) depends on the rate of energy stored in the system. The rate of energy stored in a sensible energy system is a strong function of spatial temperature distribution that governs the energy distribution in the storage medium. The present study explores the energy and capacity factor characteristics of a wire coil fitted multi-tubular SESS. A storage system is molded using M30 grade concrete of density 2200 kg/m3) and specific heat capacity 850 J/kg/K). The inlet temperature of the air, used as heat transfer fluid, is varied from 45°C to 75°C. The pitch to diameter (p/d) ratio of the wire coil insert is varied from 0.25 to 0.75 to examine its effect on energy storage/release and capacity factor. Using a (p/d) ratio of 0.5 for wire coil inserts, the maximum capacity factor of 0.98 is achieved during the charging phase of sensible energy storage at 55°C inlet air temperature and 0.029 kg/s mass flow rate of heat transfer fluid (HTF). With respect to the smooth SESS, the maximum improvement in capacity factor is found to be 29%.