Relative Height Research Articles

Validation and Error Minimization of Global Ecosystem Dynamics Investigation (GEDI) Relative Height Metrics in the Amazon

Global Ecosystem Dynamics Investigation (GEDI) is a relatively new technology for global forest research, acquiring LiDAR measurements of vertical vegetation structure across Earth’s tropical, sub-tropical, and temperate forests. Previous GEDI validation efforts have largely focused on top of canopy accuracy, and findings vary by geographic region and forest type. Despite this, many applications utilize measurements of vertical vegetation distribution from the lower canopy, with a wide diversity of uses for GEDI data appearing in the literature. Given the variability in data requirements across research applications and ecosystems, and the regional variability in GEDI data quality, it is imperative to understand GEDI error to draw strong inferences. Here, we quantify the accuracy of GEDI relative height metrics through canopy layers for the Brazilian Amazon. To assess the accuracy of on-orbit GEDI L2A relative height metrics, we utilize the GEDI waveform simulator to compare detailed airborne laser scanning (ALS) data from the Sustainable Landscapes Brazil project to GEDI data collected by the International Space Station. We also assess the impacts of data filtering based on biophysical and GEDI sensor conditions and geolocation correction on GEDI error metrics (RMSE, MAE, and Bias) through canopy levels. GEDI data accuracy attenuates through the lower percentiles in the relative height (RH) curve. While top of canopy (RH98) measurements have relatively high accuracy (R2 = 0.76, RMSE = 5.33 m), the accuracy of data decreases lower in the canopy (RH50: R2 = 0.54, RMSE = 5.59 m). While simulated geolocation correction yielded marginal improvements, this decrease in accuracy remained constant despite all error reduction measures. Some error rates for the Amazon are double those reported in studies from other regions. These findings have broad implications for the application of GEDI data, especially in studies where forest understory measurements are particularly challenging to acquire (e.g., dense tropical forests) and where understory accuracy is highly important.

Time-Varying Stability Analysis of the Trenching Construction Process of Diaphragm Wall

The stability of underground diaphragm walls is crucial for ensuring the safety and integrity of trench excavations in geotechnical engineering. This study addresses this critical issue by proposing a novel destabilization mechanism based on a sliding body model specifically designed for diaphragm wall trenching operations. The research employs an analytical framework rooted in soil mechanics and plasticity theory, utilizing limit equilibrium analysis to develop a method for calculating the minimum required slurry density and corresponding safety factor for trench stability. The study compares two distinct approaches to slurry density computation, analyzing their sensitivity to various influencing factors. Theoretical findings are validated through multiple real-world engineering case studies. Comparative analysis demonstrates the superiority of the proposed method, particularly in assessing trench stability within clay layers. Key variables influencing the safety factor are identified, including trench length, slurry density, soil friction angle, and the relative height difference between slurry and groundwater levels. Results indicate that actual slurry densities observed in practice consistently fall within the bounds predicted by the theoretical calculations. This research contributes a valuable theoretical framework to the field of diaphragm wall construction, offering improved accuracy in stability assessments and potentially enhancing safety in geotechnical engineering projects.

Experimental and numerical study on flexural performance of ultra-high performance concrete frame beams reinforced with steel-FRP composite bars

This paper presents the bending tests of four ultra-high performance concrete (UHPC) frame beams and one normal strength concrete (NSC) frame beam, all reinforced with steel-FRP composite bars (SFCBs). A comprehensive analysis was carried out, encompassing evaluation of the failure mode, crack propagation, bearing capacity, deformation, strain response, and plastic rotational capacity of the frame beams. Investigating the effects of concrete type, reinforcement type, and beam-end reinforcement ratio on the flexural performance of the frame beams was a key aspect of this study. A three-dimensional finite element (FE) model of the frame beam was established and rigorously verified. The developed model enabled a detailed parametric analysis involving the steel ratio, the yield strength of the inner core steel bar, the elastic modulus of the FRP, and the ultimate tensile strength of the SFCB. The results indicated a consistent failure mode of all frame beams: crushing of concrete at the beam-end, initiating a sequence of plastic hinge occurrence starting at the beam-end and then progressing to mid-span. The substitution of normal strength concrete with UHPC significantly enhanced various aspects of the frame beams, including the flexural capacity, deformation, ductility, ultimate energy dissipation, and plastic rotational capacity, while inhibiting the generation and expansion of cracks. Notably, the plastic rotation angle of SFCB-UHPC frame beams was 4.9 times greater than those of steel-UHPC frame beams, emphasizing the effectiveness of SFCB in enhancing the beam-end plastic rotational capacity. A decrease in the beam-end reinforcement ratio significantly reduced the flexural capacity, ultimate energy dissipation, and beam-end plastic rotational capacity, while improving ductility. Additionally, the study established a formula for calculating the equivalent plastic hinge length, utilizing the relative compressive zone height and effective section height of the beam-end controlling section as variables, which demonstrated good alignment between predicted and experimental results.

C-C Bonding in Molecular Systems via Cross-Coupling-like Reactions Involving Noncovalently Bound Constituent Ions.

Carbon-based molecules are of universal importance for a huge variety of chemical and biological processes. The complication of the structure of such molecules proceeds via the bonding of carbon atoms. An efficient mechanism for such reactions proceeds via cross-coupling, related to the association of bond-terminating counter-ions. Here, an uncommon version of such a process is investigated, with at least some ions bound in the system noncovalently and/or switching the bonding mode in due course. The analyzed sample reactions involve a single C-C bond formation in environmentally relevant halocarbon species and involve alkali-halide ion-pair components. A consistent ab initio computational study predicts the related energy barriers to alter significantly in the presence of the ion pair. Different channels are checked, with the carbon-halogen bond cleavage preceding or following the actual C-C bonding and with the counter-ions located closely or farther apart. The relative heights of the corresponding energy barriers are found to be switched by the ion pair. The above results suggest a possibility of facilitating such reactions without expensive catalysts.

Discriminating absolute depth of consecutively presented targets in the real environment with binocular disparity and relative height information

Discriminating absolute depth of consecutively presented targets in the real environment with binocular disparity and relative height information

How to get closer to actual forest stand height using GEDI? A case study in central European Scots pine stands

ABSTRACT Global Ecosystem Dynamics Investigation (GEDI) Satellite Laser Scanning mission plays a key role in forest monitoring, conducting global measurements of forest height and structure. However, the use of various stand height metrics and definitions applied to describe forest height complicates study comparisons and the selection of most suitable GEDI metric for stand height determination. Our study was focused on finding the optimal GEDI relative height (rhG) metric to describe the height of Scots pine stands. We compared GEDI rhG parameters with several metrics commonly used as reference forest stand height (a series of Airborne Laser Scanning point cloud percentiles and relative height metrics of simulated waveforms; rhSW). Results showed that GEDI rhG metrics in the 0.95–0.99 rank range can accurately describe forest stand height (ALS reference: RMSE ≤ 2.79 m; %RMSE ≤12.57%; rhSW reference: RMSE ≤ 2.80 m; %RMSE ≤12.21%). Moreover, our analyses suggested that different rhG metrics can be used to describe forest stand height depending on its height and canopy cover to increase measurements accuracy. We recommended a set of GEDI rhG metrics for adequate height measurements of Scots pine stands that can be used by forestry practitioners.

Thermal performance investigation of rhombus shape roughened solar air collector- A novel approach

Current study investigates parametric study on thermal performance of a rhombus-shaped artificially roughened absorber plate (RAP) used in solar air collector. Experimental investigations were performed in month of April–May 2024 in mechanical department of MANIT, Bhopal. Relative roughness pitch (P/e), relative roughness height (e/Dh), number of elements (W/Vr) and relative diagonal length (dr/e) in the range of 8–12, 0.0225–0.03375, 9–11, and 8–12 respectively are used as geometrical parameters for current study. Reynolds number (Re) is varied from 2000 to 14000. Thermal efficiency (ղth) is reported in terms of collector heat removal factor (FR), and collector efficiency factor (F′). A significant enhancement in ղth has been observed, ranging from 1.42 to 1.63 times higher when compared to the performance data of smooth plates. Maximum ղth of 79.48% was found at P/e = 10, e/Dh = 0.03375, W/Vr = 10, dr/e = 9.6 at mass flow rate (m˙) = 0.031 kg/s. Collector's performance parameter are reported as (FRτα) and (F0UL). value of (FRτα) and (F0UL) is reported 0.8612 and 15.82 for rhombus shape at optimal geometrical parameters.

Sodium Bicarbonate Tolerance During Seedling Stages of Maize (Zea mays L.) Lines

ABSTRACT(1) Soil alkalinization and salinization represent a growing global challenge. Maize (Zea mays L.), with its relatively low tolerance to salt and alkali, is increasingly vulnerable to saline‐alkali stress. Identifying maize genotypes that can withstand salinity and alkalinity is crucial to broaden the base of salt‐alkali‐tolerant maize germplasm. (2) In this study, we screened 65 maize germplasm resources for alkali stress using a 60 mM NaHCO3 solution. We measured fifteen morphological and physiological indices, including seedling height, stem thickness, and leaf area. Various analytical methods—correlation analysis, principal component analysis, subordinate function analysis, cluster analysis, stepwise discriminant analysis, and ridge regression analysis—were used to assess the seedling alkali tolerance of these maize germplasm resources. The physiological indices of six tested maize varieties were analyzed in greater detail. (3) The findings revealed complex correlations among traits, particularly strong negative associations between conductivity and root traits such as length, volume, surface area, diameter, and number of branches. The 15 evaluation indices were reduced to 7 principal components, explaining 77.89% of the variance. By applying affiliation functions and weights, we derived a comprehensive evaluation of maize seedling alkali tolerance. Notably, three germplasms—Liang Yu 99, Bi Xiang 638, and Gan Xin 2818—demonstrated significant comprehensive seedling alkali tolerance. Cluster analysis grouped the 65 maize germplasm resources into four distinct categories (I, II, III, and IV). The results of the cluster analysis were confirmed by multiclass stepwise discriminant analysis, which achieved a correct classification rate of 92.3% for 60 maize genotypes regarding alkalinity tolerance. Using principal component and ridge regression analyses, we formulated a regression equation for alkali tolerance: D‐value = −1.369 + 0.002 * relative root volume + 0.003 * relative number of root forks + 0.006 * relative chlorophyll SPAD + 0.005 * relative stem thickness + 0.005 * relative plant height + 0.001 * relative conductivity + 0.002 * relative dry weight of underground parts. Under sodium bicarbonate stress, morphological indices and germination rates were significantly reduced, germination was inhibited, photosynthetic pigment levels in maize leaves decreased to varying degrees, and the activities of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) significantly increased. Alkali stress markedly enhanced the antioxidant enzyme activities in maize varieties, with alkali‐resistant varieties exhibiting a greater increase in antioxidant enzyme activities than alkali‐sensitive varieties under such stress. (4) By screening for alkali tolerance in maize seedlings, the identified alkali‐tolerant genotypes can be further utilized as suitable donor parents, thereby enhancing the use of alkali‐tolerant germplasm resources and providing theoretical guidance for maize cultivation in saline‐alkaline environments.

Morphometry and morphology of the gypsum tumuli from the Sorbas karst region, SE Spain

In the Sorbas region of Spain, the gypsum karst is known for occurrences of gypsum tumuli, the peculiar weathering landforms that appear on gypsum rocks in semi-arid areas. Tumuli are small-scale domes (diameter: < 15 m, height: < 1.35 m) with empty internal chambers formed by local detachment and uplift of the surface layer of gypsum bedrock. Their origin is attributed to cyclic wetting and drying and expansive re-precipitation of gypsum in near-surface voids and pores of the rocks. Morphometric and morphological analyses of these gypsum landforms were conducted to verify and supplement data regarding their morphology. Based on linear regression equations, the geometry of the tumuli was analyzed quantitatively using pairs of the following parameters: horizontal long and short axes, relative height, thickness of the uplifted rock layer, height of the internal chamber, and others. The tumuli are limited in size – they rarely exceed 4.0 m in horizontal extension and 0.5 m in height above the surface of the surrounding terrain. Regardless of their size, they tend to preserve a rather constant plan shape, from circular to elliptical. The relative height of the tumuli is as a rule 7 to 8 times smaller than the length of their long horizontal axis, and ca. 6 times smaller than the length of the short axis. Aerial photogrammetry was used to estimate the destruction degree of gypsum tumuli, which helps to interpret their morphological changes during erosion. The appearance of a hole at the top of the form leads to the development of narrow-crater and then wide-crater tumuli. The side inlet opening leads to the formation of half-moon and then sickle shaped tumuli.

Entrance effect of curved endwall on heat transfer and flow structure in a confluent channel with pin fins

In advanced turbine blade internal cooling channels, the majority of the remaining coolant converges into the trailing edge and constitutes a confluent flow before the slot entrance. The entrance effects of curved endwalls (convex, concave) for confluent internal cooling channel are numerically investigated in this paper. The overall heat transfer performances and flow structures are compared in the slot channel with pin fin cooling at the five momentum ratios (M = 0.1–2.1). Among all the cases studied, the higher momentum inflow not only enhance heat transfer but also reduce pressure loss in the slot channel with concave endwalls. In particular, the substantial comprehensive heat transfer factor (η) increase reaches 29.4% higher than the flat endwalls at the given relative curvature height ratio of 1.83. For the models with convex endwalls, the jet-like flow improves the η at the most by 12.1% compared to the flat endwalls. As the curvature height ratio increases, the effects of curved endwalls diminish eventually. In addition, the momentum ratio determines the formation and specified impact of the above flow characteristics in the confluent flow. The curved endwalls exhibit more increase in the η at lower M.

Optimizing heat transfer in solar air heater ducts through staggered arrangement of discrete V‐ribs

AbstractThis research paper details an experimental study on airflow dynamics in a solar air heater. The heater's design incorporates unique, discrete V‐shaped ribs with staggered elements to enhance thermal performance. The study investigates the influence of various roughness parameters on flow characteristics. These parameters include a relative coarseness pitch (P/e) ratio of 12, a rib inclination angle (α) of 60°, a relative coarseness height (e/Dh) of 0.043, and a staggered element arrangement with a positioning ratio (p′/P) of 0.65. Additionally, the investigation includes scenarios with three gaps (Ng) between elements and a gap‐to‐rib width (g/e) ratio of 4. The research focuses on how changes to the Reynolds number, ranging from 3000 to 14,000, and alterations to the ratio of staggered element positioning to rib height (r/e), from 2 to 5, impact the flow dynamics. The outcomes indicate a significant boost in heat transfer performance, with the Nusselt number rising to 3.76 compared with a conventional smooth duct. The highest thermal efficiency recorded was 86%, at an r/e ratio of 3.5. These results underscore the potential of using discrete V‐ribs with staggered elements in rectangular ducts to improve heat transfer efficiency.

Comparative analysis of percutaneous vertebroplasty and kyphoplasty in the treatment of Stage III Kummell’s disease without neurological symptoms: a retrospective study

ObjectiveThis study analyzes the safety and efficacy of percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP) treatments for Stage III Kummell’s disease without neurological symptoms, comparing the advantages and disadvantages of these two minimally invasive surgical methods.MethodsA retrospective analysis was conducted on 53 patients with non-neurological Stage III Kummell’s disease treated with PVP and PKP at our hospital from December 2018 to January 2023. Patients were divided into PVP (25 cases) and PKP (28 cases) groups based on the surgical method. There were no significant differences in general preoperative data between the two groups (all p > 0.05), ensuring comparability. The study compared surgical duration, volume of bone cement injected, distribution pattern of bone cement, rate of bone cement leakage, and preoperative, postoperative, and final follow-up scores of Visual analogue scale(VAS) and Oswestry disability index(ODI). Additionally, relative anterior height of the injured vertebrae, and Cobb angle of deformity, along with their changes at preoperative, postoperative, and final follow-up stages were calculated and analyzed.ResultsNo significant preoperative differences were observed between the groups (p > 0.05). The PKP group had longer surgeries, higher cement volumes (p < 0.001), and lower leakage rates (p < 0.05), with primarily chunky cement distributions versus mixed distributions in the PVP group. No complications other than cement leakage occurred. VAS and ODI scores showed no significant changes at various time points (p > 0.05) but improved significantly from preoperative (p < 0.001). Both groups saw improved vertebral heights and Cobb angles post-surgery (p < 0.05), with more significant improvements in the PKP group (p < 0.05). Over time, both groups experienced gradual vertebral height loss and increased Cobb angles, more pronounced in the PKP group (p < 0.05). At the final follow-up, there were no statistical differences in vertebral height and Cobb angle between the two groups (p > 0.05).ConclusionThe study evaluates the safety and efficacy of PVP and PKP for Stage III Kummell’s disease without neurological symptoms, comparing the merits of both minimally invasive techniques.

Design-oriented method for the load-bearing capacity of RC columns jacketed by octagonal and spiral stirrups under axial and eccentric compression

The purpose of this study was to develop the design-oriented calculation method for the load-bearing capacity of RC columns jacketed by octagonal and spiral stirrups under axial and eccentric compression load. Based on the result of sixteen full-scale jacketed concrete columns which subjected to axial compression load, the judging method for the axial load-bearing capacity ultimate state of jacketed RC columns was determined. Then the design-oriented method for the axial load-bearing capacity of jacketed columns was proposed according to the axial load-bearing capacity ultimate state of jacketed RC columns. In addition, based on the six full-scale jacketed concrete columns which subjected to lateral cyclic load, the design-oriented calculation model for the relative compression zone height of jacketed RC columns under eccentric compression was proposed. And the calculation methods for evaluating the load-bearing capacity of jacketed RC columns with large eccentricity and small eccentricity were proposed, respectively. Furthermore, the predicted results from proposed method fitted well with the test results, which indicated that the proposed design-oriented methods were suitable for evaluating the load-bearing capacity of jacketed RC columns under axial and eccentric compression.

A Large Cohort Study of Height and Mammographic Density in Relation to Breast Cancer Risk among Korean Women.

Height and mammographic breast density are well-known risk factors for breast cancer. This study aims to investigate the association between height and mammographic density with breast cancer risk in a large population-based cohort of Korean women. This retrospective cohort study included 4,851,115 women aged 40 and older who underwent screening mammography through the Korean National Cancer Screening Program (KNCSP) between 2009 and 2014 and were followed up until 2016. Multivariable Cox proportional hazard models were employed to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between height, mammographic density, and breast cancer risk. A taller stature was associated with an increased risk of breast cancer, with women in the highest quintile of height (Q5) having a 1.54-fold [95% CI: 1.49, 1.59] greater risk compared to those in the lowest quintile (Q1). When analyzing breast cancer risk based on height and mammographic density, women in the highest quintile for height (Q5) with extremely dense breasts had a 4.51-fold [95% CI: 4.24, 4.79] greater risk compared to those in the lowest quintile (Q1) with almost entirely fatty breasts (p trend < 0.001). This first study to simultaneously examine these two variables found that height and mammographic density were independently associated with breast cancer risk in this large cohort of Korean women. Height and mammographic density can help stratify risk in screening populations for breast cancer. Careful consideration of screening strategies may be beneficial for taller women with dense breasts.

Novel mixed self-assembled monolayers of L-cysteine and methanol on gold surfaces under ambient conditions.

In this work, we carried out an experimental and theoretical study on the formation of self-assembled monolayers of L-cysteine molecules on gold surfaces in the presence of methanol as a solvent. We report for the first time L-cysteine and methanol ordered structures forming a mixed self-assembled mono-layer on Au(100) surfaces under ambient conditions. Finger-like ordered structures with a relative height of 0.10-0.20 nm, average width of 2.0 nm and variable lengths were observed using scanning tunneling microscopy under room temperature and ambient pressure conditions. Using X-ray photoemission spectroscopy, it was determined that L-cysteine molecules bind to the gold surface through the sulfur atom of their thiol group in two molecular configurations: neutral and zwitterionic. We found that the finger-like structures are the result of complex interactions of L-cysteine molecules with gold surfaces and L-cysteine molecules with methanol molecules and among all three components of the system (L-cysteine + methanol + gold surfaces). These interactions were detected through attenuated total reflectance-Fourier transform infrared spectroscopy. Furthermore, adsorbate/substrate interactions were studied by employing ab initio calculations using density functional theory, resulting in molecular arrangements formed by chains of L-cysteine pairs surrounded by physisorbed methanol molecules.

Testing the patterning cascade model of cusp development in Macaca fascicularis mandibular molars

ObjectiveMolar crown configuration plays an important role in systematics, and functional and comparative morphology. In particular, the number of cusps on primate molars is often used to identify fossil species and infer their phylogenetic relationships. However, this variability deserves renewed consideration as a number of studies now highlight important developmental mechanisms that may be responsible for the presence of molar cusps in some mammalian taxa. Experimental studies of rodent molars suggest that cusps form under a morphodynamic, patterning cascade model of development (PCM) that involve the iterative formation of enamel knots. This model posits that the size, shape and location of the first-forming cusps determines the presence and positioning of later-forming cusps. DesignHere we test whether variation in accessory cusp presence in 13 Macaca fascicularis mandibular second molars (M2s) is consistent with predictions of the PCM. Using micro-CT, we imaged these M2s and employed geometric morphometrics to examine whether shape variation in the enamel-dentine junction (EDJ) correlates with accessory cusp presence. ResultsWe find that accessory cusp patterning in macaque M2s is broadly consistent with the PCM. Molars with accessory cusps were larger in size and possessed shorter relative cusp heights compared to molars without accessory cusps. Peripheral cusp formation was also associated with more centrally positioned primary cusps, as predicted by the PCM. ConclusionsWhile these results demonstrate that a patterning cascade model is broadly appropriate for interpreting cusp variation in Macaca fascicularis molars, it does not explain all manifestations of accessory cusp expression in this sample.

Vertical flow structures on a vegetated immobile bed under wave-current conditions: Laboratory experiments

Natural revegetation alters local hydrodynamic conditions in coastal lagoons. To investigate vertical flow structures in revegetated lagoons, a series of flume experiments are implemented on an immobile bed with Phragmites australis by a certain staggered configuration. Six incident wave heights and five inflow discharges are considered. The experimental results demonstrate that wave dominates turbulent kinetic energy (TKE) distributions under wave-current conditions. Vegetation morphology plays an important role in wave-current-vegetation interactions, which regulates TKE distributions by diminishing wave effects within 70% of water depth especially (0.3 < z/h < 1). The increasing inflow discharge has positive effects on diminishment of wave effects, while the reduction of mean streamwise flow velocity is stable under the present vegetation configuration. Moreover, the practical values of vertical mean flow velocity can be obtained from the empirical equation, which includes wave effects by a quadratic polynomial relationship between the ratio of experimental values to theorical values (U/Up) and the relative wave height H0/h. Furthermore, two relationships are established between the reduction of mean streamwise flow velocity r and z/h, involving a logarithmical relationship in the lower layer (0 < z/h < 0.3), and a cubic polynomial relationship in the upper layer (0.3 < z/h < 0.7).

Nesting behaviour of Neotropical social wasps of the genus Clypearia de Saussure (Hymenoptera: Vespidae: Polistinae)

ABSTRACT Social insects have developed different nest defence strategies; for example, social wasps use nonaggressive mechanisms or aggressiveness, including stinging. This subject has been widely examined in the literature, and it may help improve our understanding of wasps’ ecology. The nesting behaviour of some genera is still poorly known. In this paper, we report new information on the nesting behaviour of the species Clypearia in different Brazilian biomes. We observed six nesting events in natural and anthropic environments of the Amazon rainforest, Atlantic forest, and Cerrado domains, sporadically from 2004 to 2022. From our observations, we suggest that Clypearia nest defence includes (i) preference for nest camouflage rather than aggressive behaviour; (ii) selection of nesting sites close to water sources in natural or anthropic environments, and eventually obtaining food from the substrate; (iii) nesting association with ants for mutual protection against predators; and (iv) variations in the nests’ height. Our records suggest nest camouflage and association with ants are strategies for nest defence. These may have influenced nest height in relation to the ground, which may also vary according to the environment explored by the species.

Modeling flow resistance and geometry of dunes bed form in alluvial channels using hybrid RANN–AHA and GEP models

Dunes formation in sandy rivers significantly impacts flow resistance, subsequently affecting water levels, flow velocity, river navigation, and hydraulic structures performance. Accurate prediction of flow resistance and dune geometry (length and height) is essential for environmental engineering and river management. The current paper introduces two models to evaluate the flow resistance and geometry of dunes formed in sand-bed channels. The first model, RANN–AHA is a hybrid artificial intelligence model using the recurrent artificial neural network (RANN) linked with the artificial hummingbird optimization algorithm (AHA) to optimize the biases and weights of the neural network model. The second model uses gene expression programming (GEP) as a nonlinear approach based on a genetic algorithm (GA) and genetic programming (GP) to explicitly determine dune characteristics. For both models, the input parameters include flow and sediment characteristics, while Manning's roughness coefficient (nM), and relative dune height, h/H or h/L, were used as output parameters where h is the dune height, H is the flow depth above the dune crest, and L is the dune length. Five different published flume data sets were compiled for the analysis. Sensitivity analysis was done using different combinations of input parameters. It was found that the combination of hydraulic radius divided by median diameter (RH/d50), Reynolds number (Re), Particle densimetric Froude number (F∗), and grain Froude number (FG) yielded the best prediction accuracy for estimating Manning nM and relative height, h/H or h/L, with a root mean square error (RMSE) = 0.00027, 0.0504, and 0.0078 and a correlation coefficient (R) = 0.9989, 0.942, and 0.9272, respectively. Model verification proved that the RANN–AHA model outperformed the GEP model and most of the previous studies available in the literature when predicting the roughness coefficient and dune geometry in sand bed channels.

Combining spaceborne lidar from the Global Ecosystem Dynamics Investigation with local knowledge for monitoring fragmented tropical landscapes: A case study in the forest-agriculture interface of Ucayali, Peru.

Improving our ability to monitor fragmented tropical ecosystems is a critical step in supporting the stewardship of these complex landscapes. We investigated the structural characteristics of vegetation classes in Ucayali, Peru, employing a co-production approach. The vegetation classes included three agricultural classes (mature oil palm, monocrop cacao, and agroforestry cacao plantations) and three forest regeneration classes (mature lowland forest, secondary lowland forest, and young lowland vegetation regrowth). We combined local knowledge with spaceborne lidar from NASA's Global Ecosystem Dynamics Investigation mission to classify vegetation and characterize the horizontal and vertical structure of each vegetation class. Mature lowland forest had consistently higher mean canopy height and lower canopy height variance than secondary lowland forest (μ = 29.40 m, sd = 6.89 m vs. μ = 20.82 m, sd = 9.15 m, respectively). The lower variance of mature forest could be attributed to the range of forest development ages in the secondary forest patches. However, secondary forests exhibited a similar vertical profile to mature forests, with each cumulative energy percentile increasing at similar rates. We also observed similar mean and standard deviations in relative height ratios (RH50/RH95) for mature forest, secondary forest, and oil palm even when removing the negative values from the relative height ratios and interpolating from above-ground returns only (mean RH50/RH95 of 0.58, 0.54, and 0.53 for mature forest, secondary forest, and oil palm, respectively) (p < .0001). This pattern differed from our original expectations based on local knowledge and existing tropical forest succession studies, pointing to opportunities for future work. Our findings suggest that lidar-based relative height metrics can complement local information and other remote sensing approaches that rely on optical imagery, which are limited by extensive cloud cover in the tropics. We show that characterizing ecosystem structure with a co-production approach can support addressing both the technical and social challenges of monitoring and managing fragmented tropical landscapes.