Permanent Regime Research Articles

Electrohydrodynamic flows inside a neutrally buoyant leaky dielectric drop

We present an experimental investigation of electrohydrodynamic (EHD) flows within a neutrally buoyant drop with a radius of 2.25 mm. Utilizing particle image velocimetry and high-speed shadowgraphy, we measure the internal circulation and reported velocity profiles in the bulk and at the interface of the drop. Two leaky dielectric liquids, silicone and castor oils, are employed as the drop and as the external phase, allowing the analysis of two shape configurations: oblate and prolate. The strength of the applied uniform electric field (from 0.125 to 1.75 kV/cm) enables the analysis covering both the small-deformation limit (CaE≪1) and drops with larger deformations. Our measurements show good agreement with the leaky dielectric model (LDM) for the small-deformation cases. The flows begin at the interface as a result of jump in the electric stresses, leading then to four counter-rotating vortices inside the drop. At a permanent regime, the analytical solutions adequately predict the radial and tangential velocity components within the drop. However, a nuanced behavior is noticed for larger deformations, where the LDM theory underpredicts the internal circulation. Moreover, due to the increased deformation, a non-uniform azimuthal profile is observed for the velocity at the interface, vθ. Transient measurements of this velocity component enlighten the dynamic response of the EHD flows of the drop. Following the available analytical solutions, the dynamic response is governed by the timescale of the deformation of the drop, τdef=μa/γ. We propose a critical value of CaE≈0.1 below which the LDM adequately describes the velocity field in both quasi steady-state and transitory regimes.

Beyond feast and famine: Cultivating hydrodynamic oxygenic photogranules with better performances under permanent feast regime

Oxygenic photogranules (OPGs) are currently obtained in permanent famine or cyclic feast-famine regimes. Whether photogranulation occurs under a permanent feast regime and how these regimes impact OPGs are unknown. Herein, the three regimes, each applied in two replicate hydrodynamic reactors, were established by different feeding frequencies. Results showed that OPGs were successfully cultivated in all regimes after 24–36 days of photogranulation phases with similar microbial community functions, including filamentous gliding, extracellular polymeric substances production, and carbon/nitrogen metabolism. The OPGs were then operated under the same sequencing batch mode and all achieved efficient removal of chemical oxygen demand (>91 %), ammonium (>96 %), and total nitrogen (>76 %) after different adaptation periods (19–41 days). Notably, the permanent feast regime obtained OPGs with the best physicochemical properties, the shortest adaptation period, and the lowest effluent turbidity, thus representing a novel means of hydrodynamic cultivating OPGs with better performances for sustainable wastewater treatment.

FULL FACTORIAL EXPERIMENTAL DESIGN AND COMPUTER SIMULATION APPLIED TO SHELL AND TUBE HEAT EXCHANGER SETUP

In the operation of heat exchangers there are some variables to be controlled, making it difficult to found optimized parameters. The aim of this study was to compare the experimental and simulated values of the outlet temperatures, as well as to understand the influence of operating variables for the equipment. It was used a shell and tube heat exchanger didactic module, with a constant cold fluid flow rate equal to 1.4 L.min 1. The experiments were carried out on the basis of a 2² full factorial experimental design with central points, as well as computer simulations in the steady state and transient regime. The higher values for heat exchange overall heat transfer coefficient determined was around 250 W.m 2.K 1. Thus, the flow regime affects the evaluated response. In addition, the computer simulation in the permanent regime presented less relative deviation. Therefore, it can be seen that although the simulations show results close to the experimental ones, there are still associated errors that should be studied and minimized, since factors such as bubble formation were not considered in the simulations. Thus, it was found that computer simulations can be used to understand the operation of heat exchangers, but they are limited to real phenomena that are not considered in theoretical mathematical models. Therefore, this study elucidates the application of statistical and computer-assisted methods as a tool to comprehend heat exchangers behavior for industrial and didactic purposes.

Dual effects of drying and urban pollution on leaf litter decomposition and shredder consumption in permanent and intermittent streams

In the present study we investigated the combined effect of flow intermittence and wastewater treatment plant (WWTP) effluent on leaf litter decomposition in two Mediterranean streams with permanent and intermittent flow regimes. The litter decomposition experiment was performed using black poplar litter bags where we measured litter mass loss, fungal biomass, aquatic hyphomycete sporulation and species richness and C:N ratio. Afterwards, the remaining litter material from the different treatments was offered to the shredder Potamophylax latipennis in a microcosm laboratory experiment, and its growth and consumption rates were studied. We hypothesised that drying would decrease leaf litter decomposition in the permanent stream more than in the intermittent stream and that WWTP effluent would compensate for drying effects when both stressors interacted. The results indicated that drying has the greatest impact on the permanent stream, decreasing decomposition, aquatic hyphomycete species richness, and leaf litter quality. In the intermittent stream, WWTP effluent decreases aquatic hyphomycete species richness, but drying increases it, showing an opposing effect and a synergistic interaction. In the permanent stream drying provoked an increase in the shredder consumption rate. Thus, the expected more frequent intermittence in rivers under climate change may threaten the processing of organic matter.

Correlation between the automated slump test and the rheological properties of Portland cement mortars

The aim of this work was to conduct a rheological assessment of mortars based on the automated slump test. Using this test to monitor the transient and permanent regime of slump and its spread, the parameters were correlated with the rheological properties of the mortars. Based on dimensionless slump/spread, yield stress and viscosity, empirical models were developed for obtaining rheological parameters, which provided correlations with good coefficients of determination (R2 > 0.85). Through analysis of the slump behaviour of the mortars, a correlation between the viscosity and the maximum slump velocity was obtained (R2 = 0.90), showing that viscosity could be determined based on the slump velocity. Furthermore, based on a physical description of the slump test related to the Reynolds number, three distinct stages in the slump process were defined: the viscous phase (characterised by high viscosities), the intermediate phase (the coexistence of viscous and inertial effects) and the inertial phase (characterised by low viscosities and a higher sensitivity to lifting of the mould). The dynamic similarity of the analysed mortars (vertical Reynolds number/radial Reynolds approximately equal to one) indicated that the shear rate could be measured based on the vertical direction of the flow (slump).

Influence Analysis of Photovoltaic and Energy Storage Systems in a Distributions System in the Context of Permanent Regime Voltage using the Opendss

This paper presents a study of the reverse power flow and the application of battery banks in the network. Five cases were carried out in which the voltage increase was verified in loads that had no PV connected through the system power flow using OpenDSS software . For this, scenarios with different percentages of distribution generation (DG) were simulated. The use of DG improves the voltage stability in the system when it is decentralized in the network, as observed in case 3. In addition, a set of batteries was inserted to present the increase of the average voltage, and the possible problem that may occur from voltage sinking. This is proven by increasing the batteries in the system, increasing the time lag of the voltage drop. To mitigate the sinking problem, energy storage should be allocated to locations where the voltage drop is greatest, as evidenced by the increased voltage level with the use of only one battery in the system.

Analysis of a network of FitzHugh-Nagumo neuron circuit coupled to an array of mechanical leg to mimic the locomotion of a multi-legged organism

A bioinspired electromechanical system that employs an array of FitzHugh–Nagumo (FN) neuron circuits designed to drive synchronically an array of mechanical legs is proposed in this paper. The schematic of the electromechanical device is transformed into an equivalent mathematical model thanks to Kirchhoff’s and Newton’s laws. The results of numerical simulations of the model generate an action potential (AP) that follows directly from the excitation of a single block of cell and does not propagate the signal in the neighboring blocks. When the stimulation time is lesser than 3-time units, the AP of the next block is generated during the repolarization of the previous cell, and the instantaneous displacement of the legs of the next block goes operational before the resting state of the previous block of the cell. For stimulation time greater than or equal to 3-time units, the AP is initiated just after the repolarization of the previous block of cells has terminated its activities and the instantaneous displacement of the leg of the next block goes operational, a direct consequence of neuron's communication without loss of amplitude in the permanent regime. Finally, straightforward motion without rotation is achieved.

Importance of Supply’s Quality in Calibration Laboratory.

In a calibration laboratory at the time of carrying out electrical measures of physics magnitudes, and upper reliability is required in order to get results of high precision. Within protections and security measures, some aspects must be considered as electrical, while another, as temperature and ambiental conditions, must not. Focusing on electrical aspects we must have into consideration that the quality of the measure rested on a reliable power source. An sabilized feed voltage ia a sign of quality and it can be obtained by two different ways. One of them is to get it from combined cycles, the other is to use an Uninterrupted Power Supply (UPS), since an UPS removes disturbances of the net, which could impede the correct measure and calibration of instruments. In order to have a supply with requared quality, which means to have an stable voltage, both in permanent regime and in transitory regime, the use of UPS's becomes necessary and recomendable. An special care must be have with micocuts, because these connections and disconnections cause anomalities in the sistem's operation, and the apearance of possible tips of voltage, which is not less important, UPS equipement are the ones that better conterac disturbances of the wave.

Real-Time Implementation of a Hybrid ESC Approach for Maximising the Extracted Photovoltaic Power Under Partial Shading Conditions

Abstract Solar energy, an available and renewable resource, can be efficiently transformed into electrical energy through the use of photovoltaic (PV) cells. The primary emphasis lies in the significance of maximising power output for economic considerations. In terms of optimising power generation, the implementation of maximum power point tracking (MPPT) techniques is imperative. A range of approaches, such as super twisting (ST) control and modified extremum seeking control (ESC-mod), are explored for their potential in enhancing the efficiency of power-generation systems. The novelty is a combination of these methods; the modified ESC has the role of finding the optimum voltage value of the global maximum power point (MPP) during the partial shading, while the super-twisting improves the performance of the system. The efficacy of the MPPT algorithm is assessed across diverse conditions, encompassing scenarios with load variations and fluctuating irradiances (uniform and non-uniform). The experimental setup involves essential components such as a PV generator, a boost converter and a resistive load. This comprehensive testing aims to evaluate the algorithm’s performance under varying circumstances, providing insights into its adaptability and effectiveness across different operational conditions. The system is modelled, simulated using Matlab–Simulink and implemented using a dSPACE 1104 card. Simulation results indicate that ST control is faster in reaching the permanent regime, but ESC-mod provides smoother performance in the permanent regime. The integration of both ST control and ESC-mod methods proves advantageous by diminishing the response time in the seeking process while concurrently ensuring a consistent and smooth operation in the permanent regime. This combined approach has undergone practical implementation and testing across diverse conditions, encompassing both optimal, healthy states and shaded environments. The results affirm the method’s ability to deliver efficient and stable performance across a spectrum of operating conditions.

A versatile micromodel technology to explore biofilm development in porous media flows.

Bacterial biofilms that grow in porous media are critical to ecosystem processes and applications ranging from soil bioremediation to bioreactors for treating wastewater or producing value-added products. However, understanding and engineering the complex phenomena that drive the development of biofilms in such systems remains a challenge. Here we present a novel micromodel technology to explore bacterial biofilm development in porous media flows. The technology consists of a set of modules that can be combined as required for any given experiment and conveniently tuned for specific requirements. The core module is a 3D-printed micromodel where biofilm is grown into a perfusable porous substrate. High-precision additive manufacturing, in particular stereolithography, is used to fabricate porous scaffolds with precisely controlled architectures integrating flow channels with diameters down to several hundreds of micrometers. The system is instrumented with: ultraviolet-C light-emitting diodes; on-line measurements of oxygen consumption and pressure drop across the porous medium; camera and spectrophotometric cells for the detection of biofilm detachment events at the outlet. We demonstrate how this technology can be used to study the development of Pseudomonas aeruginosa biofilm for several days within a network of flow channels. We find complex dynamics whereby oxygen consumption reaches a steady-state but not the pressure drop, which instead features a permanent regime with large fluctuations. We further use X-ray computed microtomography to image the spatial distribution of biofilms and computational fluid dynamics to link biofilm development with local flow properties. By combining the advantages of additive manufacturing for the creation of reproducible 3D porous microarchitectures with the flow control and instrumentation accuracy of microfluidics, our system provides a platform to study the dynamics of biofilm development in 3D porous media and to rapidly test new concepts in process engineering.

The permanent regime of temporary solutions: Housing of forced migrants in Europe as a policy challenge

Periods of forced migration to and in Europe have been common in the past decade and show no expectation of stalling due to ongoing armed conflicts, global inequalities and the adverse effects of climate change. Nevertheless, the provision of accommodation for asylum seekers and refugees continues to depend on temporary, ad hoc solutions. In the context of housing financialisation and shortage of affordable housing across European cities, this decreases opportunities for integration and securing other needs, such as jobs, language acquisition and childcare, but increases the risk of refugee homelessness and social exclusion. Based on cross-national Urban Living Labs exchanges in Leipzig, Riga, Lund, Helsingborg and Vienna, this commentary argues for a European agenda for long-term housing solutions for forced migrants in the arrival and settling phases that tackle issues from discrimination to access, to belonging. Importantly, creating long-term housing solutions for refugees would benefit whole housing systems as instruments of social inclusion.

Toward an optimal twisting-sliding mode control of a three-phase PMSM for electric vehicles

This paper deals with an optimal twisting sliding mode controller (OT-SMC) for the operation of a three phase permanent magnet synchronous machine (PMSM) in an electric vehicle (EV). In order to drive these vehicles, optimal performance is needed with robust control against real-time disturbances such as the variable load torque, uncertainties such as the parameters variation and speed variations between medium, low, and high speed as well as good performance characteristics for enhanced drive quality and longer battery time. Several conventional techniques have been applied to PMSM but they suffer from the problem of uncertainties and disturbances due to the PI regulator. A hybrid approach comprising of a robust nonlinear and optimal controller to achieve these objectives is attempted for driving electrical vehicles. This advanced hybrid controller obtained after the merger of sliding mode control (SMC) and a linear quadratic controller (LQR) is found to outperform existing controllers due to their superb performance characteristics. Furthermore, SMC is designed based on the exponential reaching law for the twisting sliding mode control (T-SMC) in order to ensure stability of the system while reducing the chattering, accelerating the rate of convergence with higher accuracy of the control performance, and the LQR is developed using the steady-state error method (N-LQR) in order to obtaining better performance characteristics. In addition, the hybridization between a twisting SMC and an optimal LQR is characterized by stabilizing and minimizing the oscillations in the permanent regime thus optimizing the system’s performance. Extensive simulation results illustrate the effectiveness and validity of the proposed control for achieving the highest performance of the PMSM.

Study of elastic interaction in collective motion phenomenon

In nature, living organisms move in a collective state of aggregation, this collective motion is influenced by the nature of the environment, the obstacles refocused during the movement and the local interaction between individuals, this interaction is responsible for avoiding collision between each individual. In this paper, we study numerically the collective motion of self-organized organisms by expanding the Langevin dynamics, in which we have modeled the interaction between individuals by an elastic force. Modeling the interaction between individuals using an elastic force gives remarkable results. This interaction has an important effect if the individuals are dispersed a lot in space, but if a certain number of particles N is exceeded, this force is of no importance and the saturation velocity becomes constant. The results of the numerical simulation show that the average velocity of the individuals goes through a transient regime before reaching the permanent regime. Moreover, the results show that the system represents a transition from a nonequilibrium state to an equilibrium state, which is similar to a second-phase transition (paramagnetic/ferromagnetic) in the absence of the magnetic field; this phase transition is observable if the distance between two individuals is greater than a critical radius noted [Formula: see text].

Financial comparison of afforestation using redwood and radiata pine under carbon regimes within New Zealand

The accurate regional characterisation of the quantity and value of carbon for key plantation species is important for both forest owners and governments. New Zealand is committed to reaching carbon net zero by 2050 and forests are currently dominated by the fast growing species radiata pine (Pinus radiata) which comprises 90% of all plantations. However, coast redwood (Sequoia sempervirens) is a promising alternative species, that is particularly suited to permanent carbon regimes, as the species is capable of rapid growth over hundreds of years. Recent increases in the carbon price have stimulated afforestation rates within New Zealand and permanent forests now comprise almost one-quarter of new plantings. Using growth models to predict carbon over a 100 year period, the objective of this study was to regionally compare carbon yields and net present value (NPV) for radiata pine and redwood carbon regimes.Model predictions show that by age 100 years, total carbon for redwood exceeded that of radiata pine within eight of the nine regions within New Zealand. Gains were greatest in the North Island, where redwood carbon exceeded that of radiata pine by on average 74%, with differences reaching up to 85% (5,203 vs. 2,808 tonnes CO2/ha at age 100 years). Under a flat baseline real carbon price of $80/tonne CO2, the NPV for redwood was very similar to that of radiata pine within four of the five North Island regions. This similarity between species was maintained across the examined carbon price range which included 26 real carbon values ranging from $35 to $160/tonne CO2. However, NPV for radiata pine exceeded that of redwood within all South Island regions as growth rates for radiata pine were greater over the first 50 years and these earlier returns have higher weighting in discounted cashflow analysis. There was marked divergence in NPV between species across all four South Island regions with increasing carbon price. The establishment of a large permanent redwood resource over the next few decades in the North Island could greatly assist New Zealand to meet its carbon obligations over both the medium to long term.

Type-2 fuzzy-logic based control of photovoltaic-hydrogen production systems

Green hydrogen will play an important role for sustainable development, it can be considered as a promising solution for energy transition. In this paper, direct and indirect-coupled configuration of hydrogen production system consisted of Photovoltaic (PV) source and electrolyzer stack are investigated. A study on power loss and efficiency in PV-electrolyzer system is conducted for both cases. Optimal matching conditions in directly coupled hydrogen system can be achieved by modifying the configuration of series/parallel cells in electrolyzer stack or PV generator. However, the energy transfer can be improved by incorporating a buck converter between PV string and electrolyzer stack. In this article, the type-2 fuzzy inference system is proposed to control the operating point of PV string by adjusting the duty cycle of control signal of buck converter. A comparison with classical MPPT methods is carried out in order to verify the efficiency of suggested technique. It has been found that the indirect-coupled hydrogen system can achieve higher energy transfer rate by ensuring continuous extracting of maximum power of PV source under various operating conditions. The obtained results, under Matlab/Simulink environment, demonstrated a satisfactory performance of type-2 fuzzy logic controller in both transient and permanent regimes. We obtain a minimal power loss value (less than 8.1%) in directly-coupled hydrogen production system, in addition a satisfactory value of efficiency (more than 93%) has been obtained.

Pedestrians in static crowds are not grains, but game players.

The local navigation of pedestrians is assumed to involve no anticipation beyond the most imminent collisions, in most models. These typically fail to reproduce some key features experimentally evidenced in dense crowds crossed by an intruder, namely, transverse displacements toward regions of higher density due to the anticipation of the intruder's crossing. We introduce a minimal model based on mean-field games, emulating agents planning out a global strategy that minimizes their overall discomfort. By solving the problem in the permanent regime thanks to an elegant analogy with the nonlinear Schrödinger's equation, we are able to identify the two main variables governing the model's behavior and to exhaustively investigate its phase diagram. We find that, compared to some prominent microscopic approaches, the model is remarkably successful in replicating the experimental observations associated with the intruder experiment. In addition, the model can capture other daily-life situations such as partial metro boarding.

Switch of tonal noise generation mechanisms in airfoil transitional flows

Large eddy simulations are performed to study tonal noise generation by a NACA0012 airfoil at an angle of attack ${\alpha = 3}$ deg. and freestream Mach number of ${M_{\infty} = 0.3}$. Different Reynolds numbers are analyzed spanning ${0.5 \times 10^5 \le Re \le 4 \times 10^5}$. Results show that the flow patterns responsible for noise generation appear from different laminar separation bubbles, including one observed over the airfoil suction side and another near the trailing edge, on the pressure side. For lower Reynolds numbers, intermittent vortex dynamics on the suction side results in either coherent structures or turbulent packets advected towards the trailing edge. Such flow dynamics also affects the separation bubbles on the pressure side, which become intermittent. Despite the irregular occurrence of laminar-turbulent transition, the noise spectrum depicts a main tone with multiple equidistant secondary tones. Increasing the Reynolds number leads to a permanent turbulent regime on the suction side that reduces the coherence level causing only small scale turbulent eddies to be observed. Furthermore, the laminar separation bubble on the suction side almost vanishes while that on the pressure side becomes more pronounced and permanent. As a consequence, the dominant noise generation mechanism becomes the vortex shedding along the wake.

Service Limits for Metal Oxide Varistors Having Cylindrical Symmetry as Function of the Ambient Temperature

This article presents an original experimental method applied to assess the stability limits of a given Metal Oxide Varistor (MOV), with cylindrical symmetry (cylinder or disk shape), as a direct relation between the ambient temperature and the service rated voltage, in the permanent operational regime. As the crossing current of a certain varistor is heavily influenced by its physical temperature, we must find an empirical relationship between these two parameters for a symmetrical configuration. Each ambient temperature can increase the temperature reference and any higher voltage will also produce an increased current, causing a uncontrolled runaway heating process, in an avalanche model. We tried to eliminate any references to technical dimensions or device values, focusing on material parameters. In the case of a symmetric MOV, we will consider the load coefficient, which is the ratio between the service DC voltage and the nominal DC opening voltage. By using experimental measurements and a simple mathematical model, we will establish the relation between the critical load coefficient and the ambient temperature in the case of symmetrical MOVs. This procedure could be applied to the design of more performant and safe surge arrester devices using existing MOVs, for all voltage levels and symmetrical configurations.

Design Optimization of a Direct-Drive Electrically Excited Synchronous Generator for Tidal Wave Energy

In the field of marine renewable energies, the extraction of marine currents by the use of tidal current turbines has led to many studies. In contrast to offshore wind turbines, the mass minimization is not necessarily the most important criterion. In that case, Direct-Drive Electrically Excited Synchronous Generators (EESG) can be an interesting solution in a context where the permanent magnet market is more and more stressed. In the particular case of a tidal turbine, the electric generator operates at variable torque and speed all the time. Its sizing must therefore take into account the control strategy and check that all the constraints are respected during the working cycle, particularly the thermal one because its permanent regime is never reached. There is no solution today that can completely solve such a sizing problem. The paper presents a specific solution. In particular, we will see that the method presented allows an avoidance of an oversizing of the generator compared to conventional methods while finding the optimal control strategy. Thus, the design optimization of an EESG is conducted considering the variable torque and speed profiles related to marine currents. The analytical model used in the paper is presented at first. In a second step, the innovative and original method that allows solving at the same time the design optimization and the control strategy (dq stator currents and rotor current) are presented. It shows how it is possible to minimize both the lost energy during the working cycle and the mass while fulfilling all the constraints (especially the thermal constraint with its transient temperature response) and keeping a reduced computation time. The case of a 2 MW tidal wave turbine is chosen to illustrate this study. Finally, the optimal design selected is validated by a 2D magnetic Finite Element Analysis (FEA).

Making the leap from ponds to landscapes: Integrating field-based monitoring of amphibians and wetlands with satellite observations

• Landsat and ground-based monitoring can be integrated to monitor wetlands and amphibians. • Landsat data supported characterizations of wetland hydrologic types and surface area trends. • Most Northern Range wetlands experienced changes in surface area over last 35 years. • Variation in snowmelt runoff was associated with changes in surface area for many wetlands. • Amphibian breeding occurred across all wetland hydrologic types. A unifying goal of wetland monitoring programs is to characterize how wetland flooding and drying regimes vary in space and time. In remote and mountainous regions, wetlands have been difficult and labor-intensive to monitor, especially at landscape scales. Here, we demonstrate how data from annual, ground-based monitoring of wetlands and amphibians in Yellowstone National Park (YNP) can be enhanced in time and spatial extent by Landsat-based observations of wetlands. Specifically, we applied spectral mixture analysis (SMA) to the Landsat time series to characterize seasonal variation in wetland surface water area over a 35-year period. This extended our monitoring record backward in time (increasing temporal extent) and allowed us to monitor wetlands outside the boundaries of our long-term monitoring catchments, thereby increasing spatial extent. Additionally, we reconstructed and characterized hydroperiod regimes of 427 wetlands across YNP’s Northern Range (NR) as ephemeral, intermittent, semi-permanent, and permanent; these categories relate to the local ecology of these sites. Across the NR, the mean summer surface water area in most wetlands declined, regardless of hydrologic regime. Declines in wetland surface water area were associated with variations in snowmelt runoff for approximately half of NR wetlands. The mean effect of runoff on wetland area was strongest for ephemeral wetlands and weakest for permanent wetlands, which were significantly larger than other wetland types. Ground-based observations from established, long-term monitoring sites (n = 37) showed that amphibians used all wetland hydroperiod regimes. Intermittent and permanent regime types contained sites where amphibian breeding was consistently detected and highlighted the importance of a portfolio of wetland types for amphibian conservation. Through the integration of ground-based and Landsat satellite datasets, we not only took the leap from ponds to landscapes, dramatically expanding the spatial and temporal extent of monitoring, but also successfully used SMA to characterize hydroperiod regimes and evaluate longer-term wetland surface water area trends across a range of wetland sizes. This work will allow wetland managers to place current conditions within longer-term trends, understand broader patterns of surface water change, analyze the relationship between wetland surface water trends and management actions, and calibrate models of climate impacts. Most importantly, the integration of field assessment and remote sensing technologies offers a strategy to detect changes in wetland extent and condition at scales ranging from individual ponds to landscapes.