Changes In Ambient Conditions Research Articles

Characterization of the airborne aerosol inlet and transport system used during the A-LIFE aircraft field experiment

Abstract. Atmospheric aerosol particles have a profound impact on Earth's climate by scattering and absorbing solar and terrestrial radiation and by impacting the properties of clouds. Research aircraft such as the Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) Falcon are widely used to study aerosol particles in the troposphere and lower stratosphere. However, transporting a representative sample to the instrumentation inside the aircraft remains a challenge due to high airspeeds and changing ambient conditions. In particular, for high-quality coarse-mode aerosol measurements, knowledge about losses or enhancements in the aerosol sampling system is crucial. In this study, the sampling efficiency of the aerosol inlet aboard the Falcon research aircraft is characterized for the first time with state-of-the art in situ measurements including sizing instruments operated behind the Falcon aerosol inlet and mounted at the aircraft wing not affected by the aerosol inlet. Sampling efficiencies were derived for different true airspeed ranges by comparing the in-cabin and ”full”-size-range particle number size distributions during 174 flight sequences with a major contribution of mineral dust particles during the ”Absorbing aerosol layers in a changing climate: aging, lifetime and dynamics” project (A-LIFE). Additionally, experimentally derived Stokes numbers were used to calculate the cutoff diameter of the aerosol sampling system for different particle densities as a function of true airspeed. As expected, the results show that the velocity of the research aircraft has a major impact on the sampling of coarse-mode aerosol particles with in-cabin instruments. For true airspeeds up to about 190 m s−1, aerosol particles larger than about 1 µm are depleted in the sampling system of the Falcon during the A-LIFE project. In contrast, for true airspeeds higher than 190 m s−1, an enhancement of particles up to a diameter of 4 µm is observed. For even larger particles, the enhancement effect at the inlet is still present, but inertial and gravitational particle losses in the transport system get more and more pronounced, which leads to a decreasing overall sampling efficiency. In summary, aerosol particles are either depleted or enhanced in the Falcon aerosol inlet, whereas transport in sampling lines always leads to a loss of particles. Here, we have considered both effects and determined the cutoff diameter for the A-LIFE transport system (i.e., the sampling lines only), the cutoff diameter of the Falcon aerosol inlet (i.e., the effect of the inlet only), and the combined effect of the inlet and sampling lines.

NIR-triggered drug delivery system based on tungsten disulfide nanosheets coated pH/temperature responsive polymer for controlled delivery of palbociclib: Release kinetics models

BackgroundPolymers that respond to changes in ambient conditions, such as physiological pH and temperature, have garnered increasing interest in the realm of drug delivery systems. In this study, a novel pH and temperature dual-responsive carrier was prepared for palbociclib delivery. MethodsThe tungsten disulfide nanosheets were functionalized with allyl glycidyl ether, allyl alcohol, and N-vinylcaprolactam, and then grafted with 2, 3-diaminopyridine. The in-vitro drug release was studied in simulated cancer (pH=5.6) and blood (pH=7.4) fluids at different temperatures. Significant FindingsThe in-vitro drug release test showed better release behavior at high temperatures in simulated cancer fluid compared to lower temperatures in simulated blood fluid, releasing about 87.53% of the entrapped drug within 6 h at 45 °C in simulated cancer fluid. The drug release shown the best fitting with the Korsmeyer-Peppas kinetic model. When the near-infrared laser irradiation was applied for 15 min, the drug release from the nanocarrier was three times higher than that without the laser irradiation. The maximum sorption capacity of the drug was achieved at approximately 79.04 mg g−1 at pH=8 for 45 min at 25 °C. The sorption procedure was found to follow the Langmuir isotherm and a pseudo-2nd-order kinetic model quite well.

Scaling the Momentum Coefficient for Active Flow Control at Various Operating Conditions

The momentum coefficient is one of the most commonly used parameters to quantify the aerodynamic performance and system output of active flow control (AFC). Estimating the momentum coefficient accurately through experiments is challenging. Several approaches exist to estimate the momentum coefficient in laboratory conditions. However, the question arises as to whether these models hold as ambient and supply conditions change during operation in flight. Therefore, computational fluidic dynamic (CFD) simulations were carried out on two exemplary AFC actuators (i.e., a fluidic oscillator and a steady jet nozzle) in a quiescent environment with supply pressure ratios ranging from 1.5 to 4; supply temperatures at 293, 550, and 800 K; and ambient altitude conditions at sea level and 10 km. When scaled with Tsup/P∞, the mass flow for different conditions collapses as a function of the pressure ratio. Furthermore, the momentum coefficient collapses when scaled with 1/P∞. The existing models to calculate the momentum coefficient hold for changing ambient and supply conditions. Therefore, these models, in conjunction with scaling parameters, can be employed during the operation of an AFC system in flight with changing conditions in order to provide the desired momentum output. The paper discusses the details of the CFD results and the derivation of the scaling parameters.

Analysis of Thermal Condition of Classrooms in Suburban Area During Corona Virus Desease using Adaptive Method

This article addresses the influence of a classroom’s thermal environment on the thermal comfort of the student when windows and vents are wide open during a pandemic, following Corona Virus Desease regulations. This research was conducted quantitatively by measuring the classrooms’ thermal environments from 08:00 to 13:00 at a suburban high school. The findings indicate that the classroom’s average air temperature (Ta) was 29.80°C, with an average relative humidity (RH) of 67.71%, an average airflow velocity (V) of 0.05m/s, an average Mean Radiant Temperature (MRT) of 29.67°C, and an average operating temperature (Top) of 29.72°C. An analysis was conducted using the web-based CBE Thermal Comfort Tool with the Adaptive Method, which can analyze the acceptance of thermal conditions based on operative temperature (Top). According to the analysis, it can be concluded that the thermal environment conditions in the morning in a “Comfortable” condition based on the ASHRAE-55 scale with the operative temperature (Top) are 27.37°C, the airflow speed (V) is 0.3m/s, and the prevailing mean outdoor temperature is 29.73°C. However, during the day, the ambient environmental conditions change, and the thermal comfort turns to “Too Warm” due to the operative temperature condition (Top), which is at the highest point of 31.46°C, with a prevailing mean outdoor temperature of 29.73°C, and an airflow speed (V) of 0.3m/s. It can be seen that the condition has not been able to meet the ASHRAE-55 standard, both in the 80% acceptability limit and the 90% acceptability limit range.

The Study of the Influence of the Tracing Speed on the Result of Surface Roughness Measurement Using the Tactile Method

This work concerns the problem of measuring surface roughness using the tactile method. The result of such a measurement is influenced by many factors, for example, the applied measurement parameters or changes in ambient conditions, e.g., temperature. The authors attempted to determine the influence of the tracing speed of the result of the profilometer tip on the roughness measurement of surfaces characterized by different types of irregularities. In the experiment, samples manufactured using various machining techniques were measured. Eleven selected roughness parameters were observed, including the most well-known ones, such as Ra, Rz, or Rt. The results obtained by the authors allowed them to determine which of the analyzed parameters are the most sensitive to changes in the tracing speed of the measuring tip, which is of great importance in the aspect of surface roughness measurements in industrial conditions. Owing to the obtained results, it is possible to determine in which cases it is possible to increase the speed of tip travel without reducing the reliability of the obtained results of surface roughness measurement.

The balance of survival: Comparative drought response in wild and domesticated tomatoes

Plants have the ability to undergo reversible behavioral, morphological, or physiological changes in response to environmental conditions. This plasticity enables plants to cope with uncertain environmental conditions, such as drought. A primary plastic trait is the rate of stomatal response to changes in ambient conditions, which determines the amount of water lost via transpiration, as well as levels of CO2 absorption, growth, and productivity. Here, we examined the differences between domesticated (S. lycopersicum cv. M82) and wild tomato (S. pennellii) species and their responses to drought stress. The plants were grown in pots in a functional phenotyping platform (FPP) in a semi-controlled environment greenhouse. We found that the domesticated tomato had a higher transpiration rate (E) and higher stomatal conductance (gs). The domesticated tomato also had greater biomass and greater leaf area under drought conditions, as compared to the wild tomato. Despite the domesticated tomato's higher E and higher gs, there was no difference between the photosynthetic rates (An) of the two lines. Moreover, the wild tomato had a higher maximum rate of rubisco activity (Vcmax), which might explain its greater leaf level and whole canopy water-use efficiency. The domesticated tomato's higher E and greater leaf area led to its earlier exposure to drought stress, as compared to the wild tomato, which maintained higher levels of soil water, enabling it to maintain steady rates of whole-canopy stomatal conductance (gsc) for extended periods. The wild tomato was also more sensitive to soil water availability and lowered its maximum transpiration rate (Emax) at a higher soil-water-content (SWC) level compared to the domesticated species. Our results suggest that the domestication of tomatoes favored morphological/anatomical performance traits over physiological efficiency.

Enhancing ventilation in street canyons using adjustable roof-level wind flow deflectors

Traffic emission impacts the air quality at both the road surface and in near road buildings. Previous research has examined the benefit of using roof-level wind catchers to reduce concentration along building facades in urban environments. Although roof-level interventions are more effective in improving the street canyon air quality in its entirety, localized re-distributions that detrimentally affect specific regions in and around the street canyons are unavoidable. In the current work, a deflector system that can adjust its position and orientation to changing ambient conditions is introduced to ensure that no particular region perpetually experiences compromised air quality. At optimal roof-level positions, the wind deflectors resulted in a local maximum and minimum of pollution removal through mean flow-induced fluxes and overall canyon concentrations respectively. In this study, the potential of the wind deflectors was first demonstrated using 2D Computational Fluid Dynamics (CFD) investigations. A maximum reduction in overall canyon concentration of 2.84 fold was predicted when the deflector was placed 2 m from the leeward walls. Subsequently, the benefit of the dynamic nature of the intervention and the efficacy of the same in a more realistic 3D city-type environment was demonstrated by considering two different pollution source conditions. The wind deflectors performed modestly for the Cross Road Pollution (CRP) source model by reducing 7%, 11% and 13% of CO exposure on the leeward wall, upwind side wall and downwind side wall without affecting the windward wall of the target street canyon. Whereas for the Side Road Pollution (SRP) source model, it reduced 91%, 32% and 34% on the same with a 17% reduction on the windward wall of the target street canyon. Finally, the concept of an adjustable deflector system was demonstrated to mitigate prolonged high exposure for building occupants exposed to changing traffic emission sources via all the surrounding building facades and at the ground.

Reciprocal transplant experiment reveals multiple factors influencing changes in coral microbial communities across climate zones

Previous studies have demonstrated the influence of external factors (environmental factors and the coral host factors) on the community structure of coral-associated bacteria. However, the internal factors, e.g. the interaction within the bacterial community or bacteria itself, have often been overlooked in studies of the coral microbiome. Hence, we performed a reciprocal transplant of corals between two different climate zones to examine the resultant alterations in coral-associated bacterial communities. The findings highlight the significance of environmental factors, host selection, and highly resilient bacteria in shaping the coral microbial composition. The results support that coral species consistently harbor specific predominant bacterial groups influenced by host selection, while locations display unique bacterial taxa due to environmental variations. The transplantation of corals into new environments leads to a gradual shift in the bacterial community, from initially resembling that of the native location to eventually resembling that of the transplanted location, emphasizing the crucial role of bacterial community composition for coral survival under changing ambient conditions. Furthermore, highly resilient bacteria that persisted throughout the reciprocal transplant experiment demonstrated their adaptability to environmental and host changes, suggesting the presence of robust adaptation or resistance mechanisms in bacterial communities. Genetic adaptations within the prevalent bacterial group, Endozoicomonas, were also observed, suggesting variations in resilience and adaptation capabilities among different phylotypes. This study highlights the need to conduct further investigations into the coral-associated bacteria themselves, as they may hold some key insights into understanding the dynamics of coral-associated microbial communities. These data also highlight some key species of coral-associated bacteria which could benefit coral in response to alterations in ambient environment.

Rapid responses are essential: adaptive temporal variation in cold tolerance of the invasive fall armyworm

Overwintering presents an ecological challenge to insects given highly contrasting environments between native versus invaded environments. The capacity for in situ adaptation through tracking temporal changes in ambient conditions through phenotypic plasticity is thus ecologically important. The fall armyworm is a tropical invasive economic pest of cereals that has become a major biosecurity threat globally. While reports suggest fall armyworm overwinter in tropical environments, little is known on how it survives the environmentally-divergent invaded environments. Here, we tested whether fall armyworm critical low temperature activity limits adaptively tracked prevailing temporal ambient environments. Using field collected populations over 2 years, we show that fall armyworm low temperature responses tracked environmental ambient temperatures. Summer 2020 collected larva had significantly lower cold tolerance (high critical thermal minima [CTmin] and chill coma recovery time [CCRT]) than those from winter seasons. However, winter collected larva had the highest cold tolerance (lower CTmin and CCRT). These results show adaptive fall armyworm responses to ambient temperature environments suggesting that both long-term and short-term responses may shape pest thermal traits and overall ecology.

Non-contact high precision pulse-rate monitoring system for moving subjects in different motion states.

Remote photoplethysmography (rPPG) enables contact-free monitoring of the pulse rate by using a color camera. The fundamental limitation is that motion artifacts and changes in ambient light conditions greatly affect the accuracy of pulse-rate monitoring. We propose use of a high-speed camera and a motion suppression algorithm with high computational efficiency. This system incorporates a number of major improvements including reproduction of pulse wave details, high-precision pulse-rate monitoring of moving subjects, and excellent scene scalability. A series of quantization methods were used to evaluate the effect of different frame rates and different algorithms in pulse-rate monitoring of moving subjects. The experimental results show that use of 180-fps video and a Plane-Orthogonal-to-Skin (POS) algorithm can produce high-precision pulse-rate monitoring results with mean absolute error can be less than 5 bpm and the relative accuracy reaching 94.5%. Thus, it has significant potential to improve personal health care and intelligent health monitoring.

Long-term environmental stability does not erode plasticity in nest building responses to changing ambient conditions.

The primary function of animal nests is to protect developing offspring from hostile and fluctuating environments. Animal builders have been shown to adjust nest construction in response to changes in their environment. However, the extent of this plasticity, and its dependence on an evolutionary history of environmental variability, is not well understood. To test whether an evolutionary history with flowing water impacts male ability to adjust nests in response to flow regime, we collected three-spined sticklebacks (Gasterosteus aculeatus) from three lakes and three rivers, and brought them into reproductive condition in controlled laboratory aquaria. Males were then allowed to nest under both flowing and static conditions. Nest building behaviour, nest structure and nest composition were all recorded. In comparison to males building nests under static conditions, males building in flowing water took longer to construct their nests and invested more in nesting behaviour. Moreover, nests built in flowing water contained less material, were smaller, more compact, neater and more elongated than nests built under static conditions. Whether males came from rivers or lakes had little impact on nesting activities, or male capacity to adjust behaviours in response to flow treatment. Our findings suggest that aquatic animals which have experienced a stable environment over a long period of time retain plasticity in nest-building behaviours that allow them to adjust nests to ambient flow conditions. This ability may prove crucial in coping with the increasingly unpredictable flow regimes found in anthropogenically altered waterways and those resulting from global climate change. This article is part of the theme issue 'The evolutionary ecology of nests: a cross-taxon approach'.

Robust MPPT Control of Stand-Alone Photovoltaic Systems via Adaptive Self-Adjusting Fractional Order PID Controller

The Photovoltaic (PV) system is an eco-friendly renewable energy system that is integrated with a DC-DC buck-boost converter to generate electrical energy as per the variations in solar irradiance and outdoor temperature. This article proposes a novel Adaptive Fractional Order PID (A-FOPID) compensator with self-adjusting fractional orders to extract maximum power from a stand-alone PV system as ambient conditions change. The reference voltage is generated using a feed-forward neural network. The conventional FOPID compensator, which operates on the output voltage error of the interleaved buck-boost converter, is employed as the baseline maximum-power-point-tracking (MPPT) controller. The baseline controller is retrofitted with an online state-error-driven adaptation law that dynamically modifies the fractional orders of the controller’s integral and differential operators. The adaptation law is formulated as a nonlinear hyperbolic scaling function of the system’s state error and error-derivative variables. This augmentation supplements the controller’s adaptability, enabling it to manipulate flexibly the tightness of the applied control effort as the operating conditions change. The efficacy of the proposed control law is analyzed by carrying out customized simulations in the MATLAB Simulink environment. The simulation results show that the proposed MPPT control scheme yields a mean improvement of 25.4% in tracking accuracy and 11.3% in transient response speed under varying environmental conditions.

Deep roots mitigate drought impacts on tropical trees despite limited quantitative contribution to transpiration

Deep rooting is considered a central drought-mitigation trait with vast impact on ecosystem water cycling. Despite its importance, little is known about the overall quantitative water use via deep roots and dynamic shifts of water uptake depths with changing ambient conditions. Knowledge is especially sparse for tropical trees. Therefore, we conducted a drought, deep soil water labeling and re-wetting experiment at Biosphere 2 Tropical Rainforest. We used in situ methods to determine water stable isotope values in soil and tree water in high temporal resolution. Complemented by soil and stem water content and sap flow measurements we determined percentages and quantities of deep-water in total root water uptake dynamics of different tree species. All canopy trees had access to deep-water (max. uptake depth 3.3 m), with contributions to transpiration ranging between 21 % and 90 % during drought, when surface soil water availability was limited. Our results suggest that deep soil is an essential water source for tropical trees that delays potentially detrimental drops in plant water potentials and stem water content when surface soil water is limited and could hence mitigate the impacts of increasing drought occurrence and intensity as a consequence of climate change. Quantitatively, however, the amount of deep-water uptake was low due to the trees' reduction of sap flow during drought. Total water uptake largely followed surface soil water availability and trees switched back their uptake depth dynamically, from deep to shallow soils, following rainfall. Total transpiration fluxes were hence largely driven by precipitation input.

Advances of responsive deep eutectic solvents and application in extraction and separation of bioactive compounds.

In recent years, it has been found that changing ambient conditions (CO2 /N2 , temperature, pH) can trigger a switchable phase transition of deep eutectic solvents, and such solvents are known as responsive deep eutectic solvents. In this work, we present the development history, properties, and preparation of responsive deep eutectic solvents, followed by the application of responsive deep eutectic solvents in the extraction and separation of bioactive compounds are presented. Importantly, the mechanism of responsive deep eutectic solvents in the extraction of bioactive compounds is discussed. Finally, the challenges and prospects of responsive deep eutectic solvents in the extraction and separation of bioactive compounds are proposed. Responsive deep eutectic solvents are considered green and efficient solvents. Some methods for extraction and separation of bioactive compounds by responsive deep eutectic solvents can increase the possibility of recycling the deep eutectic solvents, and provide higher efficiency in the extraction and separation field. It is hoped that this will provide a reference for the green and sustainable extraction and separation of various bioactive compounds.

Towards the multi-scale Kalman filtering of dynamic wake models: observing turbulent fluctuations and wake meandering

When dynamic wake models are augmented with a Kalman filter, they can provide dynamic estimates of the turbine inflows. Such estimators –especially when implemented through readily available operational data– can support a variety of practical applications in wind farm operation and monitoring, power forecasting, and others. The present work represents a first step towards a multi-scale approach for the filtering of dynamic wake models, aimed at estimating both small-fast and large-slow scales in the flow. The small-fast scales are caused by flow turbulence, which in turn also causes wake meandering, whereas the large-slow ones represent the propagation of macroscopic changes of ambient conditions (e.g., the passing of a wind direction change front throughout a farm). It is argued that the small-fast-scale problem is more difficult to address, because of the lack of measurements between turbines, and it is therefore the focus of this paper. An ensemble Kalman filter is developed that, based exclusively on power measurements from the turbines, estimates small-fast changes in wind speed and wake position. CFD simulations are used to characterize the performance of the proposed approach. Results indicate that – notwithstanding the lack of measurements of the flow as it travels from one turbine to the other– the filter is still able to provide for reasonable estimates of the inflow at the downstream machine. Additionally, it is shown that the filter typically distinguishes between effects caused by ambient flow changes from those due to wake meandering.

Numerical investigation of thermo-fluid behaviour in a channel with PCM-filled columns

Microalgae has been identified as a potential source in the production of biofuel. Photobioreactors, which are used for microalgae production, normally experience temperature variations over the diurnal cycle due to changes in ambient conditions. Such temperature variations affect microalgae growth since microalgae are sensitive to these temperature variations. Hence, the thermal regulation of photobioreactors to minimize temperature variations will result in higher yield of microalgae. The present research is aimed to investigate a novel approach to thermally regulate photobioreactors using phase change materials (PCM) where the latent heat of the material is exploited as the energy storage mechanism. The present research uses a numerical approach to study the flow and thermal behaviors in a channel with a set of thermal energy storage columns placed at some offset from each other. The research aims to investigate the transient thermal response of the channel flow in the presence of these columns. Open source CFD software, OpenFOAM, is used to numerically simulate flow in a rectangular channel containing offset PCM columns. A parametric analysis to investigate the impact of various operating and geometric properties on the heat transfer to the PCM columns showed that geometric parameters such as the gap and blockage ratios, column aspect ratio, column shape and column arrangement in the channel influence thermal energy storage in PCM-filled columns.

Quantification of Shrinkage-Induced Cracking in Oilwell Cement Sheaths

Summary Ensuring the zonal isolation of hydrocarbon reservoirs is one of the main tasks of the cement sheath, but the development of cracks and debonding between the interfaces might lead to underground water pollution and leaks of oil and gas to the environment. Restrained shrinkage of the cement sheath is one of the most significant causes of cracking, and an experimental investigation has been conducted to quantify how extensive shrinkage-induced cracking might be due to changes in ambient humidity conditions, confinement levels, and mixture compositions. The presence of lateral confinement due to the presence of shale provided an 80% reduction in the cracked area compared to unconfined specimens, but still radial cracks as wide as 200 µm, microannuli up to 100 µm, and cracked areas of 50 mm2 in a representative well section were observed. Additionally, a reduction in crack widths and potential leak paths was obtained by reinforcing the cement slurry with synthetic fibers. A detailed quantification of shrinkage-induced cracking is reported in this study, providing crack information such as position, width, and orientation as a function of time.

Air leakage detection in building façades by combining lock-in thermography with blower excitation

Air leakage in building envelopes is responsible for a large portion of the building’s heating and cooling requirements. Therefore, fast and reliable detection of leaks is crucial for improving energy efficiency. This paper presents a new approach to determining air leakages in a building’s envelope from the outside, combining lock-in thermography and thermal excitation by a blower door system. The blower creates a periodic overpressure within the building, inducing periodic temperature variations of the surfaces near the leaks on the outside surface, the façade. With the temperature variations excited at a known frequency, Fourier transforms of the time-series of the thermal images at the excitation frequency result in amplitude and phase images highlighting the areas affected by leaks. Periodic excitation and detection by an IR camera is known as lock-in thermography and is widely used to characterise semiconductor devices and in non-destructive testing. Excitation is usually achieved by optical, electrical, or mechanical energy input. For this work, measurements of outside façades have been performed with three excitation cycles of a period of 40 s at a 75 Pa pressure difference, leading to a total measurement time of only 2 min. Measurements have been performed with air temperature differences of 5 to 7 K at highly variable conditions of irradiance, wind, and cloud cover. The measurements show higher detection quality and less impact from changing ambient conditions than the state-of-the-art differential infrared thermography measurements. With the method highlighting the variations in the amplitude image only at the excitation frequency, variations caused by environmental effects are filtered out. A temperature difference as low as a few Kelvin is therefore sufficient, and large façades can be examined from the outside. This amplitude image is already clearer than an image created with differential thermography. A further reduction of unwanted artefacts in the image is demonstrated using phase-weighing of the amplitude by scalar product.

Structural basis of calmodulin modulation of the rod cyclic nucleotide-gated channel

Calmodulin (CaM) regulates many ion channels to control calcium entry into cells, and mutations that alter this interaction are linked to fatal diseases. The structural basis of CaM regulation remains largely unexplored. In retinal photoreceptors, CaM binds to the CNGB subunit of cyclic nucleotide-gated (CNG) channels and, thereby, adjusts the channel's Cyclic guanosine monophosphate (cGMP) sensitivity in response to changes in ambient light conditions. Here, we provide the structural characterization for CaM regulation of a CNG channel by using a combination of single-particle cryo-electron microscopy and structural proteomics. CaM connects the CNGA and CNGB subunits, resulting in structural changes both in the cytosolic and transmembrane regions of the channel. Cross-linking and limited proteolysis-coupled mass spectrometry mapped the conformational changes induced by CaM invitro and in the native membrane. We propose that CaM is a constitutive subunit of the rod channel to ensure high sensitivity in dim light. Our mass spectrometry-based approach is generally relevant for studying the effect of CaM on ion channels in tissues of medical interest, where only minute quantities are available.

LeafSpec-Dicot: An Accurate and Portable Hyperspectral Imaging Device for Dicot Leaves

Soybean is one of the world's most consumed crops. As the human population continuously increases, new phenotyping technology is needed to develop new soybean varieties with high-yield, stress-tolerant, and disease-tolerant traits. Hyperspectral imaging (HSI) is one of the most used technologies for phenotyping. The current HSI techniques with indoor imaging towers and unmanned aerial vehicles (UAVs) suffer from multiple major noise sources, such as changes in ambient lighting conditions, leaf slopes, and environmental conditions. To reduce the noise, a portable single-leaf high-resolution HSI imager named LeafSpec was developed. However, the original design does not work efficiently for the size and shape of dicot leaves, such as soybean leaves. In addition, there is a potential to make the dicot leaf scanning much faster and easier by automating the manual scan effort in the original design. Therefore, a renovated design of a LeafSpec with increased efficiency and imaging quality for dicot leaves is presented in this paper. The new design collects an image of a dicot leaf within 20 s. The data quality of this new device is validated by detecting the effect of nitrogen treatment on soybean plants. The improved spatial resolution allows users to utilize the Normalized Difference Vegetative Index (NDVI) spatial distribution heatmap of the entire leaf to predict the nitrogen content of a soybean plant. This preliminary NDVI distribution analysis result shows a strong correlation (R2 = 0.871) between the image collected by the device and the nitrogen content measured by a commercial laboratory. Therefore, it is concluded that the new LeafSpec-Dicot device can provide high-quality hyperspectral leaf images with high spatial resolution, high spectral resolution, and increased throughput for more accurate phenotyping. This enables phenotyping researchers to develop novel HSI image processing algorithms to utilize both spatial and spectral information to reveal more signals in soybean leaf images.