Equivalent Depth Research Articles

Evaluation of E3SM land model snow simulations over the western United States

Abstract. Seasonal snow has crucial impacts on climate, ecosystems, and humans, but it is vulnerable to global warming. The land component (ELM) of the Energy Exascale Earth System Model (E3SM) mechanistically simulates snow processes from accumulation, canopy interception, compaction, and snow aging to melt. Although high-quality field measurements, remote sensing snow products, and data assimilation products with high spatio-temporal resolution are available, there has been no systematic evaluation of the snow properties and phenology in ELM. This study comprehensively evaluates ELM snow simulations over the western United States at 0.125∘ resolution during 2001–2019 using the Snow Telemetry (SNOTEL) in situ networks, MODIS remote sensing products (i.e., MCD43 surface albedo product), the spatially and temporally complete (STC) snow-covered area and grain size (MODSCAG) and MODIS dust and radiative forcing in snow (MODDRFS) products (STC-MODSCAG/STC-MODDRFS), and the snow property inversion from remote sensing (SPIReS) product and two data assimilation products of snow water equivalent and snow depth – i.e., University of Arizona (UA) and SNOw Data Assimilation System (SNODAS). Overall the ELM simulations are consistent with the benchmarking datasets and reproduce the spatio-temporal patterns, interannual variability, and elevation gradients for different snow properties including snow cover fraction (fsno), surface albedo (αsur) over snow cover regions, snow water equivalent (SWE), and snow depth (Dsno). However, there are large biases of fsno with dense forest cover and αsur in the Rocky Mountains and Sierra Nevada in winter, compared to the MODIS products. There are large discrepancies of snow albedo, snow grain size, and light-absorbing particle-induced snow albedo reduction between ELM and the MODIS products, attributed to uncertainties in the aerosol forcing data, snow aging processes in ELM, and remote sensing retrievals. Against UA and SNODAS, ELM has a mean bias of −20.7 mm (−35.9 %) and −20.4 mm (−35.5 %), respectively, for spring, and −13.8 mm (−27.8 %) and −10.2 mm (−22.2 %), respectively, for winter. ELM shows a relatively high correlation with SNOTEL SWE, with mean correlation coefficients of 0.69 but negative mean biases of −122.7 mm. Compared to the snow phenology of STC-MODSCAG and SPIReS, ELM shows delayed snow accumulation onset dates by 17.3 and 12.4 d, earlier snow end dates by 35.5 and 26.8 d, and shorter snow durations by 52.9 and 39.5 d, respectively. This study underscores the need for diagnosing model biases and improving ELM representations of snow properties and snow phenology in mountainous areas for more credible simulation and future projection of mountain snowpack.

Pekerisモードの等価深度はいくらだろうか？

Inspired by the detection of the Pekeris mode of atmospheric free oscillations by a recent study, high-accuracy numerical calculations of the problem of determining the equivalent depth of atmospheric free oscillations are performed. Here, the computational method is largely based on a previous study, but with modifications to improve the accuracy of the calculation. Two equivalent depths are found, with values of 9.9 km and 6.6 km. The former corresponds to the Lamb mode and the latter corresponds to the Pekeris mode. These values deviate from those obtained in the previous study, especially for the Pekeris mode. The causes of this discrepancy is discussed, as well as the correspondence between the equivalent depths obtained in this study and that of the Pekeris mode detected in the recent study.

Investigation of a water equivalent depth method for dosimetric accuracy evaluation of synthetic CT

PurposeTo provide a metric that reflects the dosimetric utility of the synthetic CT (sCT) and can be rapidly determined. MethodsRetrospective CT and atlas-based sCT of 62 (53 IMRT and 9 VMAT) prostate cancer patients were used. For image similarity measurements, the sCT and reference CT (rCT) were aligned using clinical registration parameters. Conventional image similarity metrics including the mean absolute error (MAE) and mean error (ME) were calculated. The water equivalent depth (WED) was automatically determined for each patient on the rCT and sCT as the distance from the skin surface to the treatment plan isocentre at 36 equidistant gantry angles, and the mean WED difference (ΔWED¯) between the two scans was calculated. Doses were calculated on each scan pair for the clinical plan in the treatment planning system. The image similarity measurements and ΔWED¯ were then compared to the isocentre dose difference (ΔDiso) between the two scans. ResultsWhile no particular relationship to dose was observed for the other image similarity metrics, the ME results showed a linear trend against ΔDiso with R2 = 0.6, and the 95 % prediction interval for ΔDiso between −1.2 and 1 %. The ΔWED¯ results showed an improved linear trend (R2 = 0.8) with a narrower 95 % prediction interval from −0.8 % to 0.8 %. ConclusionΔWED¯ highly correlates with ΔDiso for the reference and synthetic CT scans. This is easy to calculate automatically and does not require time-consuming dose calculations. Therefore, it can facilitate the process of developing and evaluating new sCT generation algorithms.

Viability of chemical and water isotope ratio measurements of RAID ice chippings from Antarctica

AbstractThe British Antarctic Survey's (BAS) Rapid Access Isotope Drill (RAID), designed for rapid drilling to survey prospective ice core sites, has been deployed at multiple Antarctic locations over 6 years. This drilling method creates ice chippings that can be discretely sampled and analysed for their chemical and water isotopic composition. Ice sampling methods have evolved since the first uses of the BAS RAID, enabling a more quantifiable sample resolution. Here, we show that water isotope records obtained from RAID ice are comparable to those of equivalent depth resolution from proximal ice cores. Records of chemical impurities also show good agreement with nearby cores. Our findings suggest that the RAID is suitable for both chemical and isotopic reconnaissance of drilling sites. Residual contamination of certain ions is discussed, with proposed design changes to avoid this issue with future use.

The Influence of Initiation Position and Depth on Anti-Explosion Safety Performance of Concrete Gravity Dam

Based on AUTODYN finite element software, this paper studies the influence of explosive equivalent and initiation depth on concrete gravity dam, analyzes the changes of internal stress, damage degree, monitoring point speed and displacement of gravity dam under different working conditions, compares the influence of underwater explosion on gravity dam under different working conditions, and provides theoretical reference for structural protection and reinforcement of gravity dam under explosive load.

Soil carbon pools are affected by species identity and productivity in a tree common garden experiment

The formation and turnover of soil organic carbon (C), the largest terrestrial C pool, is strongly impacted by the ultimate source of that C: leaves, wood, roots, and root exudates. The quantity and quality of these inputs is determined by the identity of the plants involved. Yet substantial uncertainty surrounds the complex relationships among plant traits and soil C, precluding efforts to maximize whole-ecosystem C uptake in nature-based climate mitigation scenarios. In this study, we leveraged a biodiversity-ecosystem function experiment with trees (IDENT) to explore the effects of interspecific variation in plant traits on soil C dynamics in the very early stages of stand development (9 years since planting). Mineral soil C stocks to 5 cm depth were quantified in monospecific plots of 19 tree species planted on a former agricultural field, and analyzed in relation to tree growth and functional traits. We found that tree species identity affected soil bulk density and, to a lesser extent, the carbon content of the topsoil, and thereby total C pools. Among species and across plots, mineral soil C stocks were positively correlated with rates of tree growth and were significantly larger beneath broadleaf trees with “fast” functional traits vs. conifers with more conservative leaf traits, when comparisons were made over equivalent soil depth increments. Thus, plant functional traits mediate interspecific differences in productivity, which in turn influence the magnitude of belowground C stocks. These results highlight important linkages between above- and belowground carbon cycles in the earliest stages of afforestation.

Hybrid pencil beam model based on photon characteristic line algorithm for lung radiotherapy in small fields

Abstract Hybrid pencil beam model (HPBM) based on photon characteristic line algorithm has been presented to get accurate three-dimensional (3D) dose distribution for lung radiotherapy in small fields. In the model, we introduced a scattering factor to accurately describe the transport behavior of scattered photons and secondary electrons, combined with the equivalent depth correction and the weighted density correction. The pencil beam kernels of heterogeneous lung phantoms were redefined by the scattering factor and depth dose for a reference field by photon characteristic line algorithm. Subsequently, the 3D dose distribution in lung phantoms with density of 0.1, 0.26, and 0.4 g/cm3, was calculated by the Finite-size pencil beam algorithm in five regular fields and an irregular field for 6 MV photon beam. The dose distributions obtained by the HPBM are in agreement with those obtained by the MC simulations, with a relative error of less than 3% in most of the cases. However, there are apparent discrepancies at media interfaces and lung anterior portion. Moreover, at media interfaces, relative dose errors of the two methods decrease with the increase in field size and lung density. The depth range in which relative errors is greater than 3% increases with the increase in field size at lung anterior portion. In these examples, maximum relative errors are between 5 and 29%. Nevertheless, it is shown that the HPBM based on photon characteristic line algorithm has potential research values in lung dose calculation under conditions of small fields.

Analytical Solution of Heat Transfer Performance of Grid Regenerator in Inverse Stirling Cycle

The regenerator plays an extremely important role in the Stirling circulation. A grid regenerator can be used for inverse Stirling machines at room temperature due to its low flow resistance. This paper proposes a hexagonal grid regenerator to theoretically explore heat transfer properties in the inverse Stirling cycle and establishes an approximate analytical model to analyze the effect mechanism of working frequency, thermal diffusivity and wall thickness on the oscillation flow. The results show that the wall thickness is one of the key factors affecting the equivalent heat transfer coefficient. Specifically, too small or too large wall thickness increases the instability of the heat transfer process. The ultimate wall thickness is determined by the equivalent heat transfer coefficient and thermal penetration depth, whose optimal value ensures not only sufficient heat exchange but also the full utilization of materials. With the increase in frequency, heat exchange performance is improved monotonously. Therefore, high–frequency operation can improve the heat exchange performance of the regenerator. In addition, an optimization criterion for the size of regenerator with the specific capacity of heat transfer as the objective parameter is proposed based on the equivalent heat transfer coefficient. The optimal parameters were obtained when relative thickness was set as 0.8 mm and the equivalent heat transfer coefficient was up to 104–105 W/m2·K indicating that the grid regenerator has broad application prospects in the inverse Stirling cycle.

Influence of sub-surface deformation induced by machining on stress corrosion cracking in lead-free brass

New stricter regulations on lead (Pb) content in brass for use in certain applications is driving the industry from traditional leaded brass towards Pb-free alloys. However, machining induced surface integrity for such Pb-free alloys and related corrosion resistance are largely unknown. Two Pb-free brass alloys, CuZn38As and CuZn21Si3P, approved for use in drinking water applications, were machined under different cutting conditions, tool geometries and tool wear states. The resulting surface integrity and sub-surface deformation was characterized using nano-indentation, scanning electron (SEM) and ion microscopy, and electron backscatter diffraction (EBSD). The materials resistance to stress corrosion cracking (SCC) was assessed by exposing the machined samples to a corrosive substance in accordance with SIS 117102. The results show that tool wear is the most influencing parameter leading to stronger sub-surface deformation. This was especially pronounced for alloy CuZn38As, where for equivalent depth of deformation, the material exhibited higher degree of work-hardening compared to the other tested alloy. Subsequently, substantial stress corrosion cracking was registered for machined CuZn38As samples.

Novel light field imaging device with enhanced light collection for cold atom clouds

We present a light field imaging system that captures multiple views of an object with a single shot. The system is designed to maximize the total light collection by accepting a larger solid angle of light than a conventional lens with equivalent depth of field. This is achieved by populating a plane of virtual objects using mirrors and fully utilizing the available field of view and depth of field. Simulation results demonstrate that this design is capable of single-shot tomography of objects of size \U0001d4aa(1 mm3), reconstructing the 3-dimensional (3D) distribution and features not accessible from any single view angle in isolation. In particular, for atom clouds used in atom interferometry experiments, the system can reconstruct 3D fringe patterns with size \U0001d4aa(100 μm). We also demonstrate this system with a 3D-printed prototype. The prototype is used to take images of \U0001d4aa(1 mm3) sized objects, and 3D reconstruction algorithms running on a single-shot image successfully reconstruct \U0001d4aa(100 μm) internal features. The prototype also shows that the system can be built with 3D printing technology and hence can be deployed quickly and cost-effectively in experiments with needs for enhanced light collection or 3D reconstruction. Imaging of cold atom clouds in atom interferometry is a key application of this new type of imaging device where enhanced light collection, high depth of field, and 3D tomographic reconstruction can provide new handles to characterize the atom clouds.

A Nonexplosive Method for Simulating Stress Waves of Large-Scale Underground Explosions

In the large-scale underground explosion, the dynamic mechanical behavior of deep rock mass under the coupled loading of the high in situ stress and the explosive stress wave is difficult to study. And the coupled loading of the in situ stress and the stress waves of large-scale underground explosions are hard to simulate. Based on this problem, an experimental device was developed, and a nonexplosive method for simulating stress waves of large-scale underground explosions was presented by us. In the experimental device, the impact energy is provided by the high-pressure gas in the air chamber, the stress wave is generated by the impact of the piston, and the waveform of the stress wave is adjusted by the composite pulse shaper. The adjusted stress wave can be transmitted to the container, where the coupled loading of the stress wave and the confining stress can be realized. The stress wave that corresponded to the real explosion is obtained by the developed device, and the function of the composite pulse shaper for adjusting the waveform is verified in the experiments by using a variety of mediums for wave adjustment. The experimental and calculation results showed that the stress wave corresponding to underground explosion at kilotons of equivalent on rock mass at great depth can be simulated by the experimental device, and the simulated explosion equivalent and buried depth can be adjusted by controlling the experimental conditions.

Modulation of the Convectively Coupled Kelvin Waves by the MJO over different domains

Abstract In this study we have examined the modulation of convectively coupled Kelvin waves (CCKWs) by different Madden-Julian oscillation (MJO) states over the Indian, Pacific and Atlantic Ocean domains. Convectively active CCKW events associated with active MJO convection, suppressed MJO convection, and quiescent MJO states were derived using wavenumber-frequency filtered outgoing long-wave radiation (OLR) indices over the three domains. Composite analysis of CCKW events during different MJO states indicate that the amplitude and phase speed of CCKW are modulated by the MJO state. CCKW amplitude is stronger (weaker), and it propagates relatively slower (faster) and more (less) eastward when the MJO amplitude is strong (weak). The phase speed of CCKW is much slower over the Indian Ocean domain, while it propagates relatively faster over the Atlantic Ocean domain. It is hypothesized that the observed difference in CCKW phase speeds is related to the Gross Moist Stability (GMS). The clear linear relationship observed between GMS and CCKW phase speeds over the different domains, during different MJO states and the observed differences in CCKW vertical structures support this hypothesis. It is found that the CCKW exhibits a baroclinic vertical structure over the Indian and Pacific Ocean domains and a barotropic vertical structure over the Atlantic Ocean. Planetary-scale convection associated with the MJO reduces the static stability allowing for baroclinic modes to prevail, which in turn reduces the GMS and the effective equivalent depth, eventually slowing down the CCKW phase propagation. The results suggest that CCKW may be treated as a mixed-moisture mode.

Portable NMR for quantification of breast density in vivo: Proof-of-concept measurements and comparison with quantitative MRI

Mammographic Density (MD) is the degree of radio-opacity of the breast in an X-ray mammogram. It is determined by the Fibroglandular: Adipose tissue ratio. MD has major implications in breast cancer risk and breast cancer chemoprevention. This study aimed to investigate the feasibility of accurate, low-cost quantification of MD in vivo without ionising radiation.We used single-sided portable nuclear magnetic resonance (“Portable NMR”) due to its low cost and the absence of radiation-related safety concerns. Fifteen (N = 15) healthy female volunteers were selected for the study and underwent an imaging routine consisting of 2D X-ray mammography, quantitative breast 3T MRI (Dixon and T1-based 3D compositional breast imaging), and 1D compositional depth profiling of the right breast using Portable NMR. For each participant, all the measurements were made within 3–4 h of each other. MRI-determined tissue water content was used as the MD-equivalent quantity. Portable NMR depth profiles of tissue water were compared with the equivalent depth profiles reconstructed from Dixon and T1-based MR images, which were used as the MD-equivalent reference standard.The agreement between the depth profiles acquired using Portable NMR and the reconstructed reference-standard profiles was variable but overall encouraging. The agreement was somewhat inferior to that seen in breast tissue explant measurements conducted in vitro, where quantitative micro-CT was used as the reference standard. The lower agreement in vivo can be attributed to an uncertainty in the positioning of the Portable NMR sensor on the breast surface and breast compression in Portable NMR measurements.The degree of agreement between Portable NMR and quantitative MRI is encouraging. While the results call for further development of quantitative Portable NMR, they demonstrate the in-principle feasibility of Portable NMR-based quantitative compositional imaging in vivo and show promise for the development of safe and low-cost protocols for quantification of MD suitable for clinical applications.

Investigating the lateral dose response functions of point detectors in proton beams

Objective. Point detector measurements in proton fields are perturbed by the volume effect originating from geometrical volume-averaging within the extended detector’s sensitive volume and density perturbations by non-water equivalent detector components. Detector specific lateral dose response functions K(x) can be used to characterize the volume effect within the framework of a mathematical convolution model, where K(x) is the convolution kernel transforming the true dose profile D(x) into the measured signal profile of a detector M(x). The aim of this work is to investigate K(x) for detectors in proton beams. Approach. The K(x) for five detectors were determined by iterative deconvolution of measurements of D(x) and M(x) profiles at 2 cm water equivalent depth of a narrow 150 MeV proton beam. Monte Carlo simulations were carried out for two selected detectors to investigate a potential energy dependence, and to study the contribution of volume-averaging and density perturbation to the volume effect. Main results. The Monte Carlo simulated and experimentally determined K(x) agree within 2.1% of the maximum value. Further simulations demonstrate that the main contribution to the volume effect is volume-averaging. The results indicate that an energy or depth dependence of K(x) is almost negligible in proton beams. While the signal reduction from a Semiflex 3D ionization chamber in the center of a gaussian shaped field with 2 mm sigma is 32% for photons, it is 15% for protons. When measuring the field with a microDiamond the trend is less pronounced and reversed with a signal reduction for protons of 3.9% and photons of 1.9%. Significance. The determined K(x) can be applied to characterize the influence of the volume effect on detectors measured signal profiles at all clinical proton energies and measurement depths. The functions can be used to derive the actual dose distribution from point detector measurements.

Refraction Shift After Nd:YAG Posterior Capsulotomy in Pseudophakic Eyes: A Systematic Review and Meta-analysis.

To explore ocular refraction shift after Neodymium: yttrium aluminum garnet (Nd:YAG) posterior capsulotomy in pseudophakic eyes. A systematic literature search was performed in the PubMed, Embase, and Cochrane Library databases until November 10, 2021. Studies on the evaluation of changes in spherical equivalent (SE), cylindrical error (CE), or anterior chamber depth (ACD) after Nd:YAG laser capsulotomy were included in the meta-analysis. The review was registered in the international platform of registered systematic review and meta-analysis protocols (INPLASY202120059). A total of 805 eyes from 18 studies were included in the final analysis. The pooled mean differences in SE from baseline to postoperative follow-up points were not significant (1 hour: 0.04 diopters [D], 95% CI: -0.13 to 0.21, P = .644; 1 week: 0.04 D, 95% CI: -0.12 to 0.20, P = .640; 1 month: 0.05 D, 95% CI: -0.06 to 0.16, P = .349). There was no significant difference between baseline CE and any subsequent visit (1 week: 0.14 D, 95% CI: -0.06 to 0.33, P = .172; 1 month: 0.17 D, 95% CI: -0.04 to 0.38, P = .108). No statistical difference in ACD from baseline was observed either (1 hour: 0.01 mm, 95% CI: -0.07 to 0.09, P = .846; 1 week: -0.12 mm, 95% CI: -0.24 to 0.01, P = .079; 1 month: -0.06, 95% CI: -0.14 to 0.01, P = .110). Neither ocular refraction nor ACD changed within 1 month after laser capsulotomy, suggesting laser capsulotomy did not affect ocular refraction in short-term observation. [J Refract Surg. 2022;38(7):465-473.].

Snow Albedo Feedbacks Enhance Snow Impurity‐Induced Radiative Forcing in the Sierra Nevada

This study employs a fully coupled meteorology‐chemistry‐snow model to investigate the impacts of light‐absorbing particles (LAPs) on snow darkening in the Sierra Nevada. After comprehensive evaluation with spatially and temporally complete satellite retrievals, the model shows that LAPs in snow reduce snow albedo by 0.013 (0–0.045) in the Sierra Nevada during the ablation season (April‐July), producing a midday mean radiative forcing of 4.5 W m−2 which increases to 15–22 W m−2 in July. LAPs in snow accelerate snow aging processes and reduce snow cover fraction, which doubles the albedo change and radiative forcing caused by LAPs. The impurity‐induced snow darkening effects decrease snow water equivalent and snow depth by 20 and 70 mm in June in the Sierra Nevada bighorn sheep habitat. The earlier snowmelt reduces root‐zone soil water content by 20%, deteriorating the forage productivity and playing a negative role in the survival of bighorn sheep.

Clonal hematopoiesis in lung cancer and its impact on liquid biopsy based on targeted deep sequencing.

e20532 Background: Blood-based liquid biopsy has proved its potential in enormous clinical applications, such as cancer screening, diagnosis, treatment guidance, disease tracking and monitoring. In certain scenarios (e.g., molecular residual disease), it requires the technique to be able to detect mutation with very low frequency (0.001% ̃ 1%). The major hurdle of ultra-sensitive circulating tumor DNA sequencing is the high background noise of plasma cell-free DNA (cfDNA) and clonal hematopoiesis (CH). Here in this study, we investigated the prevalence of CH in lung cancer patients and its interference with liquid biopsy. Methods: We retrospectively analyzed cfDNA and blood cell genomic DNA (gDNA) sequencing data sets (n = 1,261) from a group of Chinese lung cancer patients. Threshold (1%) and subthreshold (0.2%) for variant allele frequency were set and compared. We focused on 23 clonal hematopoiesis genes that were selected based on previous publications. Results: CH mutations were detected in 27.68% of all the patients at the threshold and 62.01% at the subthreshold, and the detection rate increased with age. DNMT3A was the most frequently mutated CH gene, accounting for more than half of the CH mutations. The CH mutations had a higher detection rate in smokers (72%) than non-smokers (59.4%) at subthreshold. VAFs of CH mutations in cell-free DNA strongly correlated with their VAFs in gDNA (Pearson’s R = 0.92, p < 2.2x10-16), while tumor-derived somatic mutations didn’t have such correlation. Conclusions: Our study showed that clonal hematopoiesis is very common in lung cancer patients, especially when examining low-frequency mutations. Sequencing of gDNA at equivalent depth is very important to filter out CH mutation in cancer liquid biopsy.

A new analytical model for predicting overland flow and nutrient loss on hillslopes

Water and nutrient loss from farmland in the Chinese Loess Plateau reduces land productivity and generates non-point source pollution. More effort is needed to develope mathematical models that can predict runoff and nutrients in this region and explore the migration mechanisms of runoff and nutrients. In this study, the runoff submodel was based on the water balance equation and the assumption that the slope flow pattern is transitional flow. To obtain the analytical solution of the runoff submodel, the excess rainfall was considered to be fixed over a short time interval. The nutrient loss submodel assumed that raindrop splash was the only way for nutrients to transfer to runoff from soil, and the equivalent mixing depth increased with the passage of runoff time. A total of 16 sets of runoff data and 64 sets of nutrient data under 16 simulated rainfall events were used to validate the model. The runoff submodel and nutrient loss submodel accurately simulated the runoff and nutrient loss processes, and the R2 values were between 0.813 to 0.981 and 0.609 to 0.982, respectively. The global sensitivity of the newly developed model was analyzed using Sobol’s method. The sensitivity of the runoff submodel to the shape factor of the ponding profile k was higher than that to the slope topographic synthesis coefficient SC. The sensitivity of the nutrient loss submodel to the initial equivalent mixing depth EMD0 and parameter m was higher than that to the raindrop-detached water transfer rate er. Therefore, the prevention and control of agricultural non-point source pollution require improvements in soil surface conditions to reduce the equivalent mixed layer depth, which can effectively reduce the loss of soil nutrients. The results of this study provide theoretical insights that will aid the control of soil and nutrient loss in the Chinese Loess Plateau.

Alternative Management of River Watershed with Batulesa Method From Environmental Aspects

The research was conducted in the Meto Batulesa watershed, with a watershed area of 8,968 ha, located between two regencies, Kupang and Kupang city. The purpose of this research is to calculate the actual erosion rate and tolerable erosion, so that conservation alternatives can be found. Based on the map of land units, there are 19 land units that are then used for soil sampling, slope, observation of soil management and soil conservation. The sampling method used purposive sampling, the data taken to calculate erosion estimates using the Universal Soil Equation (USLE) method, while the erosion tolerance used the concept of equivalent depth and resource life based on (Hammer 1981) and (Arsyad 2010). The results of the study show that the highest actual erosion value of 225.68 tons/hectare/year and the lowest is 2.78 tons/hectare/year. The value of erosion tolerance among 19 land units, in which are 10 land units is above the erosion tolerance so that they require alternative management, while 9 of them are without conservation. Alternative management in the form of modifications to the values of C and P include 1. Terrace Gulud: Corn + Beans + Mulch of Plant Remnants, 2. Corn + Soybean with rotational cropping pattern + mulch of crop residues, 3. Bench terrace + corn cassava/soybean, 4. Secondary forest and 5. Primary forest.

Experimental study and mathematical model development for the effect of water depth on water production of a modified basin solar still

Freshwater is constantly shrinking with the confindness of water resources. Therefore, desalination of seawater is given great attention. Renewable energy sources also become of high importance to reduce carbon emissions. Thus, this study is concerned with the design, fabrication, and testing of a new single-slope double-basin solar still as a renewable energy-driven desalination system. It differs from the conventional solar stills by having two basins. The experiments were conducted to compare the performance of both conventional and modified solar stills. As a design parameter that substantially affects the performance, the still water depth was investigated. A new straightforward, accurate model is developed to predict both systems' performance for the design and optimization within a maximum deviation of ±6.6%. The results indicated that the day's productivity for the new and conventional stills at 2 cm water depth was 2.855 and 1.785 L/m2 per day, respectively, by an increase of 59.9% with a thermal efficiency improvement of 61.3%. Also, a rise in the equivalent water depth de from 2 cm to 3 cm reduces the accumulated productivity by 14.36% and 15.41% for the SSDBSS and SSSS, respectively. Additionally, the daily thermal efficiency of the SSDBSS and SSSS is 25% and 15.5% for water depth de of 2 cm, respectively. The maximum values of the total heat transfer coefficient were also evaluated to be 15.4 and 55 W/m2.°C for the lower and upper basins of the modified system, respectively, and 30.18 W/m2.°C for the conventional system.