Horizontal Size Research Articles

Unravelling the clonal trait space: Beyond above‐ground and fine‐root traits

Abstract Plant trait variation is constrained by mechanical and energetic trade‐offs as attested by the global spectrum of plant form and function and the fine‐root economics space for above‐ and below‐ground traits. However, traits that are key for fitness maintenance in some plant groups, such as clonal and bud bank traits, have not yet been integrated within the frameworks provided by the above‐ground and the fine‐root economics space. By using an extensive dataset encompassing above‐ground, fine‐root, clonal and bud bank traits of 2000 species of Central European herbs, we asked whether clonal and bud bank traits correspond to the placement of species in the above‐ground or fine‐root trait space. Perennial clonal and non‐clonal herbs show indistinct positioning within the above‐ground and fine‐root trait spaces. This extends and reinforces previous fragmentary evidence of weak correlations between clonal and bud bank traits and above‐ground trait dimensions. Additionally, we identify for the first time a limited correlation between clonal and fine‐root traits as well. This disconnection suggests that clonal traits operate independently from other trait spectra. For this reason, we introduce the concept of a ‘clonal trait space’ for clonal herbs. The first dimension of this space is defined by bud bank size and the persistence of clonal connection, reflecting a gradient of species specialisation for on‐spot persistence and tolerance to disturbance (persistence dimension). The second dimension, defined by multiplication rate and lateral spread, reflects a specialisation axis for clonal multiplication and horizontal size dimension (clonal multiplication dimension). Clonal trait dimensions add non‐redundant information to the above‐ground or fine‐roots trait space. Synthesis: We champion the integration of the persistence and clonal multiplication dimensions from the ‘clonal trait space’ into the frameworks provided by the above‐ground trait and the fine‐root economics spaces, thereby enhancing our comprehension of the multifaceted trait strategies exhibited by plants.

Climatologically invariant scale invariance seen in distributions of cloud horizontal sizes

Abstract. Cloud area distributions are a defining feature of Earth's radiative exchanges with outer space. Cloud perimeter distributions n(p) are also interesting because the shared interface between clouds and clear sky determines exchanges of buoyant energy and air. Here, we test using detailed model output and a wide range of satellite datasets a first-principles prediction that perimeter distributions follow a scale-invariant power law n(p) ∝ p-(1+β), where the exponent β = 1 is evaluated for perimeters within moist isentropic atmospheric layers. In model analyses, the value of β is closely reproduced. In satellite data, β is remarkably robust to latitude, season, and land–ocean contrasts, which suggests that, at least statistically speaking, cloud perimeter distributions are determined more by atmospheric stability than Coriolis forces, surface temperature, or contrasts in aerosol loading between continental and marine environments. However, the satellite-measured value of β is found to be 1.26 ± 0.06 rather than β = 1. The reason for the discrepancy is unclear, but comparison with a model reproduction of the satellite perspective suggests that it may owe to cloud overlap. Satellite observations also show that scale invariance governs cloud areas for a range at least as large as ∼ 3 to ∼ 3 × 105 km2, and notably with a corresponding power law exponent close to unity. Many prior studies observed a much smaller range for power law behavior, and we argue this difference is due to inappropriate treatments of the statistics of clouds that are truncated by the edge of the measurement domain.

Modulation of Rayleigh–Bénard convection with a large temperature difference by inertial nonisothermal particles

This study investigates the modulation by inertial nonisothermal particles in two-dimensional Rayleigh–Bénard (RB) convection with non-Oberbeck–Boussinesq effects due to a large temperature difference. Direct numerical simulations combined with a Lagrangian point-particle method are performed for 1×106≤Ra≤1×108 and 6.1×10−3≤Stf≤1.2, where the Rayleigh number Ra and Stokes number Stf measure the vigor of convection and particle response time, respectively. The typical aspect ratio Γ = 1 is of primary concern. We find that a horizontally arranged double-roll flow pattern prevails at intermediate Stokes numbers with optimal heat transfer efficiency, which has never been reported before. Compared to the single-phase cases, the heat transfer efficiency is enhanced by a factor of two or three. For micro Stokes numbers, unlike cases in the Oberbeck–Boussinesq limit where the addition of particles causes a small amount of flow structure changes, in this study, it is observed that a tiny volume load of particles could actually induce significant flow oscillations or trigger fluid instability for Ra=106; conversely, for medium Rayleigh numbers (Ra=107), it is found that flow reversal is slightly suppressed by small particles. For intermediate Stokes numbers, where particle–fluid couplings are strongest and a wealth of new phenomena emerge, special attention is paid. Considering different aspect ratios, after the addition of particles, it is found that closed RB systems tend to contain an even number of convection rolls rather than odd ones. Quantitatively, heat transfer also improves significantly for various aspect ratios for intermediate Stokes numbers. Subsequent investigations reveal that the narrowing of the horizontal size of convection rolls cannot fully explain the significant enhancement; instead, it should also be attributed to strong couplings between particles and fluid dynamics. Moreover, it is found that both momentum and thermal couplings play crucial roles in enhancing heat transfer efficiency.

Facile Preparation of Ternary Cd0.9Pb0.1Se Quantum Dots Toward Photoelectrochemical Photodetectors

AbstractDue to the inherent high dark current of photoelectrochemical (PEC)‐type photodetectors (PDs), there is a tricky challenge to detect weak light. In this work, high‐quality Cd0.9Pb0.1Se quantum dots (CPS QDs) are prepared by thermal injection method, with horizontal size of 6.3 nm and thickness of 3.5 nm. The CPS QDs are directly utilized to construct the working electrode of PEC‐type PDs. The effects of experimental parameters on the photo‐response behavior are systematically studied, and optimized photocurrent density of 7.1 µA cm−2 and photo‐responsivity (Rph) of 2.75 mA·W−1 are achieved. Most importantly, the obvious photocurrent signals are observed under a light power density as low as 5.6 µW cm−2. For this interesting weak light detection, apparent Rph of 6.96 mA·W−1, detectivity of 1.2 × 109 Jones, and external quantum efficiency of 2.37% are achieved. Therefore, this work not only develops CPS QDs‐based PDs but also provides an example for PEC‐type PDs in weak light detection.

Improving the urban wind flow prediction efficiency of target area by considering its surrounding buildings impact

Rapid urbanization has caused various urban environmental challenges, including the emergence of urban heat island and air pollution. Urban wind flow is a crucial factor shaping the urban environment, which needs effective prediction and design. Computational fluid dynamics is commonly used for prediction and design of urban wind environment. However, high-accuracy simulation of wind flow, especially considering the layouts of full-scale and complex buildings, requires intensive computational resources. Typically, simulations simplify the surrounding building layouts (e.g., building layers) of target areas, potentially impacting simulation accuracy. It is imperative to determine appropriate building layers around different-scale target areas for effective wind flow simulation. This work explored the simulated wind flow characteristics of multi-scale (local, micro, and building-scale) target areas with different building layers defined as H, L, H/L, and L/H (H and L representing the vertical and horizontal maximum sizes of target area). The recommended building layers for local-scale, micro-scale, and building-scale target areas were at least 3L, 4H, and 5H, respectively, ensuing the relative errors between simulated and measured wind velocities remained below 20 %. This method largely reduced the calculation time by 73 % compared with full-scale simulation. This work can provide guidelines for fast prediction and design of urban wind environment, further promoting the sustainable development of urban cities.

Comprehensive thermal performances study on fin-enhanced thermo-activated building envelopes with anisotropic heat injection capacity

The thermo-activated building envelopes (TABEs) possess special structural and energy features, providing a unique opportunity for the energy-efficiency measures of non-transparent building envelopes to shift towards low-carbon properties. To address the long-standing issue of heat charging efficiency that has plagued conventional TABEs (ConTABEs), fin-enhanced TABE (FinTABE) with anisotropic charging capacity is proposed. The dynamic thermal behaviors and charging performances of FinTABEs are numerically studied with a validated model, and then the effects of fin materials, fin heights, fin thicknesses, fin numbers, installation directions, pipe spacings, and insulation thicknesses are investigated. Results indicate that the directional heat injection measures can effectively improve the performances of opaque envelopes. Compared with ConTABEs, the further improvement in daily room heat loss of FinTABEs under different charging conditions is 0.73 % to 52.92 %, while the maximum increase of daily total heat loss does not exceed 3.5 %. Besides, the performance enhancement in FinTABEs will gradually reach the upper limit when the vertical fins’ thermal diffusion capacity exceeds that of brass/aluminum, the characteristic height reaches 0.6, or the fin thickness reaches 1.5 mm. Results also indicate that the vertical fins can significantly expand the heat accumulation area inside FinTABEs and change the circular heat accumulation shape into ellipse shapes. Differently, the horizontal fins are conducive to increasing the horizontal size of the heat accumulation area, but further installing fins in the horizontal direction has a slight effect on increasing the vertical height of the heat accumulation area. In addition, the directional heat injection design can effectively suppress the shrinkage of the heat accumulation area when the insulation thickness is reduced, and the insulation material can be reduced by more than 40 % while maintaining similar performances as standard ConTABE.

A station‐based evaluation of near‐surface south foehn evolution in COSMO‐1

AbstractThis study investigates the skill of the Consortium for Small‐scale Modeling (COSMO) model (v5.7) at 1.1 km horizontal grid size in simulating the near‐surface foehn properties and evolution for five south foehn events and a five‐year‐long climatology. A significant near‐surface cold bias is found during foehn, with an average bias of K in the Rhine Valley in the five foehn cases and K in the major northern foehn valleys in the five‐year foehn climatology. The cold bias tends to be larger in the stronger and moister deep foehn events. Sensitivity experiments are carried out to examine the possible causes of the cold bias, including changes to the parameterization of the land–atmosphere interaction, 1D turbulence parameterization, and horizontal grid spacing. Most sensitivity experiments have only a very minor impact on the cold bias, except for the model run with a horizontal grid spacing of 550 m. The 550‐m COSMO run shows a reduced cold bias during foehn hours and also an improvement in the simulated foehn duration and northward foehn extent. By inspecting the vertical dimension, we found that the near‐surface cold bias downstream might partly originate upstream. A further contribution to the downstream cold bias is likely due to insufficient vertical mixing in the foehn flow. The latter is possibly enhanced in the 550‐m model run, leading to a less stably stratified atmosphere in the lower few hundred meters of the atmosphere and a reduction of the reported model cold bias.

Quantifying the Impact of Vertical Resolution on the Representation of Marine Boundary Layer Physics for Global-Scale Models

Abstract While GCM horizontal resolution has received the majority of scale improvements in recent years, ample evidence suggests that a model’s vertical resolution exerts a strong control on its ability to accurately simulate the physics of the marine boundary layer. Here we show that, regardless of parameter tuning, the ability of a single-column model (SCM) to simulate the subtropical marine boundary layer improves when its vertical resolution is improved. We introduce a novel objective tuning technique to optimize the parameters of an SCM against profiles of temperature and moisture and their turbulent fluxes, horizontal winds, cloud water, and rainwater from large-eddy simulations (LES). We use this method to identify optimal parameters for simulating marine stratocumulus and shallow cumulus. The novel tuning method utilizes an objective performance metric that accounts for the uncertainty in the LES output, including the covariability between model variables. Optimization is performed independently for different vertical grid spacings and value of time step, ranging from coarse scales often used in current global models (120 m, 180 s) to fine scales often used in parameterization development and large-eddy simulations (10 m, 15 s). Uncertainty-weighted disagreement between the SCM and LES decreases by a factor of ∼5 when vertical grid spacing is improved from 120 to 10 m, with time step reductions being of secondary importance. Model performance is shown to converge at a vertical grid spacing of 20 m, with further refinements to 10 m leading to little further improvement. Significance Statement In successive generations of computer models that simulate Earth’s atmosphere, improvements have been mainly accomplished by reducing the horizontal sizes of discretized grid boxes, while the vertical grid spacing has seen comparatively lesser refinements. Here we advocate for additional attention to be paid to the number of vertical layers in these models, especially in the model layers closest to Earth’s surface where climatologically important marine stratocumulus and shallow cumulus clouds reside. Our experiments show that the ability of a one-dimensional model to represent physical processes important to these clouds is strongly dependent on the model’s vertical grid spacing.

Thermographic analysis of topographically controlled Marangoni–Rayleigh–Bénard convection in a fluid with temperature-dependent properties

Thermal convection in a shallow layer of liquid with an array of metallic (aluminum) cubic elements evenly spaced along the bottom is investigated experimentally using a thermographic technique. The blocks protrude upwards and, although they are prevented from reaching the free surface, their vertical thickness, horizontal size and overall number can be varied parametrically. This configuration is used with the two-fold intention to produce a kind of obstruction or blockage in the flow and, at the same time, to feed thermal convection with heat directly injected into the fluid at a certain distance from the (hot) floor. It is shown that tuning of the physical topography at the bottom and the difference of temperature between the liquid and the external (gaseous) environment is instrumental in enabling internal feedback control over the spontaneous flow behavior. For a fixed geometry and temperature difference, variations in the emerging pattern can also be produced by changing the thickness of the liquid layer, which indirectly provides evidence for the additional degree of freedom represented by the relative importance of buoyancy and Marangoni effects. Overall, such results suggest a novel possible route to the realization of convective motions with complex (but surprisingly regular) organization, which have been rarely obtained in earlier attempts based on conventional setups.

Sliding limbus-conjunctival flaps for minimizing the pterygium recurrence: a prospective tertiary care institute study.

Objective: To describe the surgical technique and long-term outcomes of sliding limbus-conjunctival flaps to treat primary pterygium. Methods: Our single-center, single-surgeon-based, prospective study (part of the postgraduate thesis) included primary pterygium patients. We included the larger pterygium in bilateral cases for our research. All patients underwent pterygium excision and reconstruction by sliding limbus-conjunctival flaps technique to minimize the recurrence rates. Similar surgical steps and drugs were used for all the enrolled patients. Two ophthalmologists (SS and MK) evaluated all cases for blinding purposes. A minimum follow-up of 12 months was ensured in all cases. Results: Fifty eyes of 50 patients underwent the sliding limbus-conjunctival flaps surgery at a mean age of 50.40 ± 15.05 years. There were 27 (54%) males and 23 (46%) females with nasal pterygium (100%), having an average horizontal size of 2.96 mm. A "with the rule" astigmatism was seen in 44 (88%) eyes with a horizontal keratometry value of 42.00 ± 2.83, which increased significantly to 42.23 ± 2.02 (p>0.05) after surgery. The visual acuity was improved by 1 Snellen's line in 21 cases, 2 lines in 4 cases, and by 3 lines in 1 case. No change in visual acuity was seen in 24 cases. The early minor postoperative complications were self-resolving. At a mean follow-up of 14.5 months, the recurrence was found in 2 patients (4%), one in the 3rd and the other in the 9th month. Conclusion: The sliding limbus-conjunctival flaps technique is a simple, safe, and efficient procedure for primary pterygium cases. Pterygium surgery positively affects the visual acuity and keratometry values in most patients, making it a cosmetic and functional ophthalmic surgical procedure.

Compact wideband filter with wide stopband using transition-free spoof surface plasmon polaritons

In this article, a newly spoof surface plasmon polaritons (SSPPs) is proposed and used to design a compact wideband bandpass filter (BPF). Different from the traditional SSPP unit cell with one-shaped structure, the unit cell of the proposed SSPPs consists of an H-shaped slotline and a bilateral T-shaped slotline. Benefiting from the hybrid structure, no transition portion is needed for impedance matching in the design of the microwave filter, which highly reduces the horizontal size of the SSPPs-based filter. The transition structure of microstrip to slotline provides a capacitance with a highpass frequency response, which enables the realization of a passband by cooperating with the natural lowpass property of SSPPs. Also, the upper and lower cutoff frequencies of the proposed filter can be adjusted independently by the key parameters. Besides, a wide upper stopband can be obtained by properly designing the SSPPs unit cell and the microstrip to slotline structure. Finally, a well-designed BPF operated at 1.3–6.2 GHz and its upper stopband rejection reaching 20 GHz is fabricated and measured. The test results are in good agreement with the simulations, which verifies the feasibility of the proposed structure and design method.

Brash ice macroporosity and piece size distribution in ship channels

Merchant vessels' performance on brash ice plays an important role in navigation in fast ice conditions in Northern Baltic ports. Among many parameters, the piece size distribution and macroporosity of the brash ice influence the accuracy of the model simulations of ship performance in brash ice. These properties also govern the brash ice accumulation and consolidation in ship channels. The current work presents analyses of macroporosity and piece size distribution from three full-scale brash ice channels investigated during winters 2020–21 and 2021–22. The results provide insights into brash ice macroporosity and piece size distribution. Smaller brash ice pieces exhibited higher porosity. On each measured cross-section, the average macroporosity ranged from 1.4% to 23%, with standard deviations of 3.8% and 16%, respectively. Porosity variations were observed in relation to equivalent brash ice thickness, the number of ship passages, and cumulative freezing air temperatures. Total porosity and the channel's brash ice porosity initially increased with breaking events and then stabilized at approximately 23% and 30%, respectively, after 9 passages. In contrast, side ridge porosity increased initially (up to 23%) and subsequently decreased. The initial total, brash ice and side ridge maximal porosities after the breaking event were estimated equal to 25%, 35% and 30%, respectively. The first two channels, which were navigated a total of 9 and 10 times, had an average degree of brash ice consolidation equal to 0.84 and 0.76, and an average degree of side ridge consolidation equal to 1.1 and 1.0, respectively. The third channel, characterized by frequent navigation, exhibited a consolidation degree of 0.82 for brash ice and 1.35 in the side ridges. The average vertical piece size across all cross-sections ranged from 0.28 m to 0.52 m with standard deviations of 0.16 m and 0.25 m. The average horizontal piece size ranged from 0.33 m to 0.4 m with standard deviations between 0.2 m and 0.34 m. The horizontal piece size distribution of brash ice was best described by the probability density function of a three-parameter lognormal distribution.

Design and optimization of circularly polarized dielectric resonator antenna array based on Al2O3 ceramic

A comprehensive design of an ultra-broadband circularly polarized (CP) dielectric resonator antenna (DRA) array operating in the C-band for fifth-generation (5G) communication systems is presented in this paper. The objective is to achieve a compact antenna size capable of receiving and transmitting CP electromagnetic waves over a wider bandwidth. The material chosen for the dielectric resonator (DR) is Alumina (Al2O3) ceramic, known for its low dielectric loss and exceptional mechanical properties, making it an ideal candidate for the DR. The proposed design utilizes a 2 × 2 array of cross-shaped DRs, fed by a compact circular phase-shift feeding network with double-point feeding. This configuration results in a 3-dB axial ratio (AR) bandwidth of 48.7 % and an impedance matching bandwidth (IMB) of 53.2 %. The antenna's horizontal size is reduced to 1.17 × 1.17λ02, and the gain is significantly enhanced by exciting multiple Mie resonances in the stacked DRs, yielding a measured peak gain of 12.48 dBic. These outstanding features position the CP DRA array as an excellent choice for 5G communication systems.

Vertical Resolution Impacts Explicit Simulation of Deep Convection

AbstractThe aggregation of tropical convection greatly influences the mean‐state of the atmosphere, altering humidity distributions, total atmospheric radiative cooling, and cloud amounts. Although studies have demonstrated the sensitivity of convective aggregation to horizontal resolution and domain size, few studies have explored the impact of vertical resolution on convective aggregation. Here, we investigate the impact of vertical resolution on simulations of deep convection and convective aggregation using the System for Atmospheric Modeling convection resolving model. We analyze simulations of tropical radiative‐convective equilibrium with varying vertical levels (32, 64, 128, and 256) across small (100 km), medium (700 km) and large (1,500 km) domains. We demonstrate that relative humidity and cloud fraction decrease with increasing vertical resolution as a result of reduced turbulent mixing. Vertical resolution also influences the occurrence of, onset time, and equilibrium intensity of aggregated convection, and also appears to affect the sensitivity of convective aggregation to domain size. Understanding how simulated convection aggregates, as well as its simulated sensitivity to model formulation, is critical for making and interpreting future predictions of global climate change.

Determination of microwave instability threshold of storage ring based on longitudinal bunch asymmetry characterization

In this study, a novel method is proposed to measure the microwave instability (MWI) threshold of the storage ring by means of the ultrafast photon detection streak camera system. It provides an additional and complementary diagnostic tool for determination of the MWI threshold of the current storage ring. Compared to other conventional measurement methods, this scheme can realize the more accurate measurement of the MWI threshold current with the remarkable advantages of simple optical architecture, good robustness, and high accuracy. In the experiment, the MWI threshold current of the Hefei Light Source-II (HLS-II) is obtained as 12.77 ± 0.54 mA corresponding to 123.6 kV of the nominal radio-frequency (RF) voltage by measuring the current dependence of the bunch asymmetry factor, under single-bunch operation mode. With a further adjust RF voltage to 100.2, 110.2, 130.3, and 140.2 kV, the turbulent threshold currents are acquired to be 11.11 ± 0.90, 11.74 ± 0.47, 13.21 ± 0.68, and 13.78 ± 0.82 mA, respectively. Additionally, the applicability, feasibility, and reliability of this method are further verified by experimentally observing the beam characteristic behaviors of the energy spread broadening and horizontal beam size widening. From experimental verification and comparative analysis, it is proved that this reported approach is valid for measuring the MWI threshold of the storage ring. This method is importance for the study of the beam instability mechanisms and related longitudinal beam dynamics in storage ring, which is also useful for machine debugging and beam status analysis.

The 3D Seismic Survey Design of South Walio Offshore, Indonesia: Optimizing the 3D Survey Design Parameters

The background of this research is to support the plan to carry out 3D seismic acquisition in the Salawati Kepala Burung Working Area located in Sorong Regency. The 3D seismic design study was applied to better understand the physical properties of the Mesozoic clastic reservoir in the Salawati basin and its surroundings, especially in the offshore area. The study aims to evaluate the parameters of a reliable 3D seismic acquisition design to meet efficiency in financing in realizing the 3D seismic data acquisition program. Determine the recording parameters to image the Kais Formation and Waripi Formation targets by building a geophysical analysis model using existing 2D data and well-log information. Based on this model, using the Kais and Waripi formation properties to calculate and analyze vertical and horizontal resolution, bin size, aperture migration, and maximum offset. Synthetic acquisition 2D modeling is applied in this study to perform vertical and horizontal resolution analysis and obtain optimum and reliable bin size parameters and aperture migration. With this knowledge, we calculate the theoretical parameters of the survey. After determining the most critical theoretical parameters of the study, the next step is to determine the distance between the source and receiver. Then define the recording template. It is done by considering the bin size for the 3D model, offset boundaries, and suitable folds for inner targets. In the second, an analysis of the other two most important attributes is carried out, namely the offset and azimuth distribution. It is realized that every 3D survey design compromises technical factors affecting 3D survey costs starting from the technical requirements of field activities. The results of this study are recommendations and suggestions for two main alternative models of recording parameters and templates in the form of ideal source-receiver layout models, namely orthogonal and diagonal, and the minimum prerequisites that are expected to be able to map and determine the characteristics of the shallow and deep play type models in the South Walio offshore areas.

Computational Domain Size Effects on Large-Eddy Simulations of Precipitating Shallow Cumulus Convection

Idealized large-eddy simulations of shallow convection often utilize horizontally periodic computational domains. The development of precipitation in shallow cumulus convection changes the spatial structure of convection and creates large-scale organization. However, the limited periodic domain constrains the horizontal variability of the atmospheric boundary layer. Small computational domains cannot capture the mesoscale boundary layer organization and artificially constrain the horizontal convection structure. The effects of the horizontal domain size on large-eddy simulations of shallow precipitating cumulus convection are investigated using four computational domains, ranging from 40×40km2 to 320×320km2 and fine grid resolution (40 m). The horizontal variability of the boundary layer is captured in computational domains of 160×160km2. Small LES domains (≤40 km) cannot reproduce the mesoscale flow features, which are about 100km long, but the boundary layer mean profiles are similar to those of the larger domains. Turbulent fluxes, temperature and moisture variances, and horizontal length scales are converged with respect to domain size for domains equal to or larger than 160×160km2. Vertical velocity flow statistics, such as variance and spectra, are essentially identical in all domains and show minor dependence on domain size. Characteristic horizontal length scales (i.e., those relating to the mesoscale organization) of horizontal wind components, temperature and moisture reach an equilibrium after about hour 30.

Electron Energy Spectrometer for MIR-THz FEL Light Source at Chiang Mai University

The linear accelerator system of the PBP-CMU Electron Linac Laboratory has been designed with the aim of generating free-electron lasers (FELs) in the mid-infrared (MIR) and terahertz (THz) regions. The quality of the radiation is strongly dependent on the properties of the electron beam. Among the important beam parameters, the electron beam energy and energy spread are particularly important. To accurately measure the electron beam energy, the first dipole magnet in the bunch compressor system and the downstream screen station are employed as an energy spectrometer. The A Space Charge Tracking Algorithm (ASTRA) software is used for the design and optimization of this system. Simulation results demonstrate that the developed spectrometer is capable of accurately measuring the energy within the 5–25 MeV range. The screen station system is designed and constructed to have the ability to capture a beam size with a resolution of 0.1 mm per pixel. This resolution is achieved with a screen-to-camera distance of 1.2 m, which proves sufficient for precise energy measurement. The systematic error in energy measurement is found to be less than 10%, with a minimum energy spread of 0.4% achievable when the horizontal beam size remains below 3 mm.

Thermal boundary condition studies in large aspect ratio Rayleigh–Bénard convection

We study the influence of thermal boundary conditions on large aspect ratio Rayleigh–Bénard convection by a joint analysis of experimental and numerical data sets for a Prandtl number Pr=7 and Rayleigh numbers Ra=105−106. The spatio-temporal experimental data are obtained by combined Particle Image Velocimetry and Particle Image Thermometry measurements in a cuboid cell filled with water at an aspect ratio Γ=25. In addition, numerical data are generated by Direct Numerical Simulations (DNS) in domains with Γ=25 and Γ=60 subject to different idealized thermal boundary conditions. Our experimental data show an increased characteristic horizontal extension scaleλ̃ of the flow structures for increasing Ra , which due to an increase of the convective heat transfer also leads to an increase of the Biot number (Bi) at the cooling plate. However, we find the experimental flow structure size to range in any case in between the ones observed for the idealized thermal boundary conditions captured by the simulations: On the one hand, they are larger than in the numerical case with applied uniform temperatures at the plates. On the other hand, they are smaller than in the case of an applied constant heat flux, the latter of which leads to a structure that grows gradually up to the horizontal domain size. We are able to link this observation qualitatively to theoretical predictions for the onset of convection. Furthermore, we study the effect of the asymmetric boundary conditions on the heat transfer. Contrasting experimental and numerical data reveals an increased probability of far-tail events of reversed heat transfer. The successive decomposition of the local Nusselt number Nuloc traces this effect back to the sign of the temperature deviation Θ̃, eventually revealing asymmetries of the heating and cooling plate on the thermal variance of the generated thermal plumes.

Modeling temporal and spatial variations of biogeochemical processes in a large subtropical lake: Assessing alternative solutions to algal blooms in Lake Okeechobee, Florida

Study region:Algal blooms (ABs), often exacerbated by excess nutrients from anthropogenic activities, can pose serious risks to public health, fisheries, and ecosystem structure and functions. Lake Okeechobee is located in southcentral Florida (USA), and with a surface area of 1730 km2, it is the largest subtropical lake in the United States. This lake is shallow, nutrient-rich, and subject to frequent and intense blooms of cyanobacteria, some of which are toxic. Study focus:In this study, a three-dimensional (3D) model was developed, coupling long-term monitoring data with complex physical, chemical, and ecological processes at fine spatial (15–1000 m horizontal mesh size) and temporal (1 h) resolution. We used this model to understand the influence of environmental factors and nutrient management on ABs dynamics in Lake Okeechobee. New Hydrological Insights for the Region:The model showed that ABs mostly developed in shallow nearshore regions near canal outlets, and then spread over the lake as a result of prevailing winds and currents. Hypothetical scenario modeling showed that reducing both nitrogen and phosphorus inputs by 50%–75% would be more effective at reducing ABs in the lake than targeting a single nutrient. The model could be used as a tool to assess the effectiveness of different nutrient management strategies in Lake Okeechobee and its watershed, while the framework could be adopted to other large water bodies facing similar issues.