Determination Of Volume Research Articles

Sampling volume evaluation of seven electromagnetic soil moisture sensors

The sampling volume of electromagnetic (EM) soil moisture sensors is of significant interest due to the diverse applications for which they are utilized. However, this volume can vary considerably based on multiple factors, including the number, spacing, and length of sensor rods, as well as the operational frequency. The sensor's volume of influence is dictated by electric field lines or ‘fringing fields’ that develop between pairs of powered electrodes. This study involved the development of an accurate sensor positioning system employed to characterize the EM sensor's electrical fringing field in 3-directional - x, y, and z space. Sensor outputs were recorded at mm increments beginning with the sensor positioned 20 mm above the air-water interface followed by incremental immersion into a water bath until the maximum sensor output was achieved. For each measurement cycle, the sensor was repositioned to test signal output approaching the air-water interface in −x, +x, −y, +y, −z, and +z orientations. The sensor sampling volume was determined based on the normalized 99% output value, which was assumed to represent the sensor position relative to an air-water interface where the sensor fringing field just begins to ‘sense’ or to become impacted by the air phase, thereby reducing the signal amplitude. Our results vary somewhat from other studies using a similar evaluation approach, leading us to conclude that EM-sensor sampling volume determination is both complex and imprecise as a result of the global sensor market's varied circuits and electrode configurations. EM soil moisture sensors evaluated in this study exhibited sampling volumes of 386 cm3 (TDR-315), 66 cm3 (TDR-310H), 398 cm3 (CS655), 45 cm3 (EC-5), 40 cm3 (HydraProbe II), 148 cm3 (WET150), and 49 cm3 (TEROS 12), which were smaller than manufacturer reported volumes.

A Method to Improve the Accuracy for the Comparison of Consecutively Determined Upper Limb Cross-Sectional Area Profiles of Test Subjects: Impact on (Segmental) Limb Volume and Local Limb Circumference.

Background: Chronic edema management depends on measuring small volume changes over time. Therefore, a highly sensitive, accurate, and reliable technique is needed to objectively judge sequential measurements. Methods and Results: The prototype of the Peracutus Aqua Meth (PAM), a new volumetric measuring device, was used in an experimental study. Thirty-nine healthy test subjects were measured three times. The measuring principle of the PAM is based on obtaining a profile of cross-sectional areas along the length of an object or limb. Besides total arm volumes, the volume of any chosen segment can be determined. The utmost tip of the middle finger appeared to be an unreliable reference point. Instead, the concept of "hand median" was introduced to align and compare profiles of cross-sectional areas of sequential measurements. Using the hand median strongly improved the measuring accuracy, rendering standard deviation values of 0.4%-1.3% for (segmental) volume determination. Conclusions: Measurements with the PAM show that accurate local/segmental volume determination of a limb is possible. Standard deviations of less than 1.3% are easily obtained for cross-sectional area and volume determination.

Determination of the REV size for heterogeneous rocks with different grain sizes: Deep learning and numerical approaches

Accurate determination of the representative elementary volume (REV) size plays a pivotal role in analysing the mechanical properties and failure processes of heterogeneous rocks in complex engineering environments. In this study, a novel microstructure modelling strategy (NMMS) for determining the REV size is proposed by combining deep learning and an improved phase-field method (PFM). Micro- and macroscale experiments are systematically conducted to determine the real microstructural characteristics and mechanical properties of heterogeneous rocks with different grain sizes. On the basis of this experimental evidence, geometric models of different sizes were reconstructed through deep learning to avoid the limitations of human-based methods, and an improved PFM was used for numerical calculations. These models were then employed to perform numerical tests under uniaxial loading conditions, and the coefficient of variation was introduced to determine the REV size of heterogeneous rocks with different grain sizes. The research findings indicate that the final REV size is the maximum value of the REVs defined by the evaluation properties within an acceptable coefficient of variation. At a criterion of 5% for the coefficient of variation, the REV sizes are 60 mm×60 mm, 70 mm×70 mm, and 90 mm×90 mm for fine-medium-grained (FMG), medium-grained (MG), and coarse-grained (CG) rocks, respectively. Furthermore, the REV determined by the NMMS was applied to investigate the effects of microstructure on macromechanical properties and damage evolution under triaxial loading conditions. The numerical results show that the NMMS can accurately predict the macromechanical properties and microcracking patterns of heterogeneous rocks, especially the intracrystalline cracks in feldspar, the interfacial cracks in gravel, and the “voids” of cracks in biotite. This research can provide some basic references for the optimal choice of the REV size of heterogeneous rocks.

Innovative and Cost‐Effective Approaches to the Measurement of Sediment Levels in Small Water Reservoirs

ABSTRACTSedimentation in small water reservoirs poses a critical challenge with significant environmental, economic, and social implications. To address this issue, this study will employ three measurement techniques—GNSS RTK Trimble R8s, Echolot HDS LIVE 7 with Active Imaging 3‐in‐1, and the Mivardi Carp Scout bait boat—to assess sediment levels in Žebětínský Pond in Brno, Czech Republic. The research reveals that each method offers distinct advantages and limitations. Through measurement and triangulated networks, the study creates a digital terrain model that facilitates the determination of reservoir volume and sediment levels. The comparison shows that the cost‐effective alternatives, Echolot HDS LIVE 7 and Mivardi Carp Scout, provide sufficiently accurate results. The evaluation shows that while the GNSS RTK Trimble R8s has the highest level of accuracy and is unique in its ability to measure both along the shoreline of the reservoir and the hard bottom, it comes with increased costs and logistical challenges. The Echolot HDS LIVE 7 and Mivardi Carp Scout offer efficient, cost‐effective solutions that are suitable for a quick estimate of sediment thickness. This research contributes to the use of reliable mathematical models and water management strategies, advocating for a pragmatic approach to the selection of methods based on the project characteristics. The study provides valuable insights into sediment measurement techniques, guiding future endeavors in reservoir management and environmental conservation. It is also used to easily indicate the loss of arable land in the catchment upstream of the reservoir.

ОЦЕНКА АНТРОПОГЕННОЙ НАГРУЗКИ НА ВОДОСБОР БАССЕЙНА РЕКИ ТОБЫЛ ОТ ИСТОЧНИКОВ ЗАГРЯЗНЕНИЯ С МАТЕМАТИЧЕСКИМ МОДЕЛИРОВАНИЕМ КАЧЕСТВА ПОВЕРХНОСТНЫХ ВОД

Based on a systematic analysis of the structure and dynamics of water resource usage in the catchment area of the Tobyl River basin, the dynamics of the formation of geoecological conditions of water use in the economic sectors within the Kostanay region of the Republic of Kazakhstan were studied. The analysis revealed a significant load from return waters and pollutants, indicating a high and potentially catastrophic pressure that requires regulation of both natural and anthropogenic activities to ensure the region’s sustainable development in the future. A generalized water use scheme for the Kazakh part of the Tobyl River basin was developed, which facilitates the formation of mathematical, physical, and chemical indicators for water management and hydrochemical balance equations. This, in turn, allowed for the creation of a mathematical model of water quality and the determination of the maximum permissible discharge volume of return waters in the river basins. The model ensures compliance with sanitary-epidemiological standards and helps preserve the ecological state of water bodies while supporting the planning of water protection measures to achieve the desired level of water quality in the river.

Residual Red Blood Cell Volume in Extracorporeal Blood Circuit After Hemodialysis: A Single-center Study.

The factors contributing to blood loss during HD procedures remain underexplored. This study aimed to quantify blood loss during HD and identify the potential factors associated with it. The study included 70 ESRD patients undergoing HD. After dialysis, the extracorporeal blood circuits were rinsed with 1,000 mL of 0.05% NH3 solution in distilled water, and hemoglobin (Hb) levels were measured. Univariate regression was used to assess the linear relationship between residual red blood cell (RBC) volume and various parameters, including HD mode, dialyzer surface area, ultrafiltration goal (UFG), hypotension during HD, blood flow rate, activated partial thromboplastin time (aPTT), and C-reactive protein (CRP). Multivariate regression was also conducted to explore the relationships among these parameters. The mean RBC volume remaining in the extracorporeal blood circuit after HD was 1.6 ± 0.9 ml (mode: 1.0, range: 0.3-6.5 ml). When converted to whole blood volume per patient, the mean blood volume was 5.3 ± 3.0 ml (median: 4.1 ml, mode: 4.0 ml, range: 1.0-19.0 ml). Multivariate analysis identified the dialyzer surface area as the only significant determinant of residual RBC volume. After HD, the remaining RBC volume in the extracorporeal blood circuit varies from 1.6 to 6.5 ml. When the RBC volume was converted to whole blood volume for each case, the blood loss ranged from 1.0 to 19.0 ml. Dialyzer surface area was the only significant determinant of residual RBC volume.

Exploring the Application of Advanced Chromatographic Methods to Characterize the Surface Physicochemical Properties and Transition Phenomena of Polystyrene-b-poly(4-vinylpyridine)

The linear diblock copolymer polystyrene-b-poly(4-vinylpyridine) (PS-P4VP) is an important copolymer recently used in many applications such as optoelectronics, sensors, catalysis, membranes, energy conversion, energy storage devices, photolithography, and biomedical applications. (1) Background: The surface thermodynamic properties of PS-P4VP copolymers are of great importance in many chemical and industrial processes. (2) Methods: The inverse gas chromatography (IGC) at infinite dilution was used for the experimental determination of the retention volumes of organic solvents adsorbed on copolymer surfaces as a function of temperature. This led to the variations in the free energy of interaction necessary to the evaluation of the London dispersive and polar acid–base surface energies, the polar enthalpy and entropy, the Lewis acid–base constants, and the transition temperatures of the PS-P4VP copolymer. (3) Results: The application of the thermal Hamieh model led to an accurate determination of the London dispersive surface energy of the copolymer that showed non-linear variations versus the temperature, highlighting the presence of two transition temperatures. It was observed that the Lewis acid–base parameters of the copolymer strongly depend on the temperature, and the Lewis base constant of the solid surface was shown to be higher than its acid constant. (4) Conclusions: An important effect of the temperature on the surface thermodynamic properties of PS-P4VP was proven and new surface correlations were determined.

Uncertainty Evaluation for Determination of Sibutramine in Health Food by HPLC-MS/MS

High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to determine the content of sibutramine in health foods according to the BJS 201701 standard Determination of Compounds such as Sibutramine in Food. By evaluating each uncertainty component, the influencing factors of the uncertainty were identified and the expanded uncertainty of sibutramine detection in health foods was provided. Using the example of illegal addition of sibutramine to health products, the HPLC-MS/MS method was used for qualitative screening and quantitative analysis of samples. The sources of uncertainty in the quantitative results were analysed, including sample weighing, sample volume determination, standard solution preparation, standard curve fitting and determination of sample repeatability. The synthetic relative standard uncertainty of the measurement results was calculated and the expanded uncertainty was reported. By optimizing the liquid phase conditions, the sample can be detected within 5 min with a linear correlation coefficient of 0.998. When the content of sibutramine in health products was 42.2 mg/kg, the extended uncertainty of the results was 4.56 mg/kg (k = 2) with a 95% confidence interval. Among the various components affecting the results of detection, the uncertainty introduced during the process of preparing the standard solution has the greatest impact on the results. A proper evaluation of the uncertainty, detailed analysis and quantification of the various sources of uncertainty can help to improve the reliability of test results.

Effects of representative elementary volume size on three-dimensional pore characteristics for modified granite residual soil

The determination of the Representative Elementary Volume (REV) is vital for comprehending the behavior of soil structural characteristics within the micro-to-macro framework. This study utilizes X-ray computed tomography to provide a detailed microscopic exploration of how waste cement, glass powder, and straw fibers contribute to the reduction of permeability in granite residual soils. Based on the pore reconstruction analysis of soil samples, the effect of REV size on the three-dimensional pore characteristics of modified granite residual soil is extensively studied. The results indicate that varying sizes of REV greatly affect the pore structure, porosity, fractal dimension, and permeability. Specifically, as the REV size increases, these parameters initially exhibit fluctuations characterized by uncertainty, ultimately stabilizing at a threshold value of 5000 μm. The incorporation of glass powder and straw fibers enhances the compactness of the soil while reducing the average diameter of connected pores. The alteration in the frequency distribution of connected pores redefines flow pathways, disrupting the preferential channels originally provided by larger pores, which is a primary factor that leads to the reduced permeability of the modified soil. These findings offer valuable references for determining the REV in modified soils, aiding future research in effectively saving time and computational costs.

Coordinated Planning of Soft Open Points and Energy Storage Systems to Enhance Flexibility of Distribution Networks

With the large-scale penetration of distributed generation (DG), the volatility problems of active distribution networks (ADNs) have become more prominent, which can no longer be met by traditional regulation means and need to be regulated by introducing flexible resources. Soft open points (SOP) and energy storage systems (ESS) can regulate the tidal currents on spatial and temporal scales, respectively, to improve the flexibility of ADN. To this end, in-depth consideration of DG admission is given to establish flexibility assessment indicators from the power side of ADN. The conditional deep convolution generative adversarial network (C-DCGAN) is used to generate the output scenario of DG. On this basis, the SOP and ESS two-layer planning models, which take account of the potential for improvement in the flexibility of ADN, are constructed. Among them, the upper layer is the site selection and volume determination layer, which considers the economy of the system with the optimization objective of minimizing the annual integrated cost; the lower layer is the operation optimization layer, which considers the flexibility of the system and takes the highest average daily flexibility level as the optimization objective. The planning model is solved using genetic algorithm-particle swarm optimization (GA-PSO) and second-order cone programming (SOCP). The case analysis verifies the rationality and effectiveness of the planning model.

The association between slow-wave sleep and choroid plexus calcifications in older adults. Results from the sleep disorders substudy of the Atahualpa Project cohort.

ObjectiveIt has been suggested that choroid plexus calcifications (CPC) may be associated with glymphatic system dysfunction and with disturbed slow-wave (N3) sleep. If this is the case, volumetric analysis of CPC could be used to estimate the functional ability of the glymphatic system. However, data on this association is limited. This study aims to assess the association between percentages of N3 sleep – used as a putative marker of glymphatic system activity – and the volume of CPC in older adults. Patients and methodsCommunity-dwelling individuals aged ≥60 years enrolled in the Atahualpa Project Cohort received head CTs (for automated determinations of CPC volume) and a single-night polysomnography (PSG) for quantification of N3 sleep percentages. Multivariate linear regression and non-parametric models were fitted to assess the association between these variables. ResultsA total of 125 older adults (median age: 65 years; 32 % males) were included. The mean percentage of N3 sleep was 12.4±9.1 %, and the mean volume of CPC was 655±345.3 µL. Non-parametric locally weighted scatterplot smoothing showed that the volume of CPC increased as the percentage of N3 sleep increased, but only when N3 sleep is reduced (up to 12 % of total sleep time). The significance disappeared when PSG parameters were included in the model as well as in participants with normal N3 sleep percentages. ConclusionsStudy results suggest that in the presence of severe reductions in N3 sleep, increased CPC volume may be a manifestation of choroid plexus compensation or adaptation, and not necessarily dysfunction.

Determination of Demand for LNG in Poland

This study was aimed at improving the energy efficiency of the distribution of liquefied natural gas (LNG) as shipping fuel in the southern Baltic Sea. The objective of this study was to determine the demand for LNG for maritime shipping by analyzing the distribution of the resource from the water side (ship-to-ship). LNG was chosen due to the location of the LNG terminal in Świnoujście within the analyzed water area, where a problem has arisen in the southern part of the Baltic Sea regarding fuel supply for vessels due to the lack of developed infrastructure along the coast. An analysis was conducted to optimize the size of the LNG fleet and infrastructure facilities. Seeking compliance with Annex VI to the MARPOL 73/78 Convention, adopted by the International Maritime Organization (IMO), shipowners see potential in the switch from conventional fuels to LNG. As one of the alternative solutions, it will contribute to reducing harmful emissions. Determination of the LNG distribution volume requires the identification of LNG storage facility locations, specifying the number of LNG-powered ships (broken down by type) and the number of LNG bunkering ships. The first part of this study contains a detailed analysis of the number of sea-going ships that provide services in the southern part of the Baltic Sea and the world’s number of LNG bunkering ships. The database contains a set of the characteristics required to determine the optimal demand for LNG, where LNG bunkering vessels are capable of supplying fuel within the shortest possible time and covering the shortest possible distance to LNG-powered ships. The characteristics include the type of ship, requested LNG volume, the speed of LNG bunkering ships, the distance between LNG facilities, and the loading rate (the volume of fuel received per time unit). Based on the collected data, the volume of LNG distribution was determined using MATLAB R2019a software. The remainder of this study contains a description of the conducted research and results of an analysis of the traffic density in the Baltic Sea. The results were obtained on the basis of data from the Statistical Yearbook of Maritime Economy and IALA IWRAP Mk2 2020 software. The number of LNG-powered ships and number of LNG bunkering ships were specified, and the demand for LNG for the area under analysis was determined.

Reliability of a 2D-Panoramic Ultrasound System for the Determination of Muscle Volume in Older Hospitalized Patients.

Reliability of muscle thickness assessed in B-mode ultrasound has been confirmed in adults but remains a less direct assessment of muscle mass than muscle volume (MV). The aim of this prospective monocentric study was to assess the interday reliability of MV determined by the 2D-panoramic ultrasound in older hospitalized patients.Ten participants hospitalized in geriatric ward (mean age = 84) underwent 2 sessions of panoramic ultrasound scanning 1 week apart for MV assessment and DXA for leg lean mass (LLM) assessment when it was possible. The interday reliability of MV assessed using the intraclass correlation coefficient (ICC) was excellent, whatever was the muscle analyzed: ICC = 0.99 for tibialis anterior; ICC = 0.99 for vastus lateralis; ICC = 1 for rectus femoris. The pilot analysis of its association with leg lean mass revealed a good association between the vastus lateralis MV and LLM, but this needs to be confirmed on a larger number of participants (Pearson correlation coefficient = 0.91, P = 0.03).The 2D-panoramic ultrasound system for the determination of MV was reliable in older hospitalized patients with measurements performed on the patient's bed. MV seemed to be more correlated to LLM than muscle thickness. Future research will need to reduce the data processing time maybe with automation of data measurement.

Modelling beach volume changes caused by moderate and weak hydrodynamic conditions

The goals of this study were the calibration of the XBeach model for moderate and weak hydrodynamic conditions in 2D mode and the determination of the volumetric changes induced by them. An evaluation of model performance was made based on the Brier Skill Score (BSS), the visual match of the profile shape (VMS), the absolute volumetric change error (m3/m) and the relative volumetric change error (%). An analysis of accuracy in determining volumetric changes in the dune coast, with XBeach applied, provided an average absolute error in determination of volumetric changes of 4.0 m3/m for a significant storm and 1.5 m3/m for moderate and weak hydrodynamic conditions in a 2D model calibration process. Simulations of morphological changes caused by moderate and weak hydrodynamic conditions for seven timeframes classified into three groups have been run in 2D mode. Within a validation process, the average absolute error in the determination of volumetric changes in the beach was ranging from 0.64 m3/m to 2.42 m3/m depending on the group of hydrodynamic conditions. A high value of the correlation coefficient (R) between the measured and modelled balance of volumetric changes (m3/m) for all timeframes – 0.79 and for the ‘strongest’ group no. 3 – 0.91 were revealed. For the remaining groups, i.e., group no. 1 and no. 2 of hydrodynamic conditions, no such correlation was observed. Furthermore, the temporal analysis of the sum of beach volumes proved that a rising trend was observed over 4 months. Thus, moderate and weak hydrodynamic conditions dominated the accumulation within the area of study. XBeach reflected this trend well, producing a difference between the measured and modelled sum of volumes at the end of the timeframe of 7.27 m3/m, which is close to the volume determination error by the model.

Rainfall event separation and determination of the water quality volume

A procedure is presented and demonstrated for identifying the minimum interevent time for automatic separation of rainfall events and the subsequent use of the event statistics to determine the water quality volume. The proposed procedure for identifying the minimum interevent time is more robust that the conventional approach that requires interevent times to have an exponential distribution. The procedure is validated in South Florida and at locations in Athens (Georgia), Roanoke (Virginia), and St.Louis (Missouri). Minimum interevent times of 6h, 6h, 12h, and 9h, respectively, were found at the study locations, and it was demonstrated that the interevent times do not generally have an exponential distribution. Conventional determination of the water quality volume does not formally consider the influence of the drain time in sizing the water quality storage basin, and a procedure is presented herein for taking the drain time into account. The procedure is demonstrated at the study locations using multiple rainfall-runoff models. It is shown that a maximum drain time of 24h would not generally be adequate in South Florida, but would be adequate in Athens, Roanoke and St.Louis, however, a maximum drain time of 48h would not generally be adequate at all locations.

Patient selection, ventricular tachycardia substrate delineation and data transfer for stereotactic arrhythmia radioablation. A Clinical Consensus Statement of the European Heart Rhythm Association (EHRA) of the ESC and the Heart Rhythm Society (HRS).

Stereotactic arrythmia radioablation (STAR) is a novel, non-invasive and promising treatment option for ventricular arrythmias (VA). It has been applied in highly selected patients mainly as bail-out procedure, when (multiple) catheter-ablations, together with anti-arrhythmic drugs, were unable to control the VAs. Despite the increasing clinical use there is still limited knowledge of the acute and long-term response of normal and diseased myocardium to STAR. Acute toxicity appeared to be reasonably low but potential late adverse effects may be underreported. Among published studies, the provided methodological information is often limited, and patient selection, target volume definition, methods for determination and transfer of target volume, and techniques for treatment planning and execution differ across studies, hampering pooling of data and comparison across studies. In addition, STAR requires close and new collaboration between clinical electrophysiologists and radiation oncologists, which is facilitated by shared knowledge in each collaborator's area of expertise and a common language. This clinical consensus statement provides uniform definition of cardiac target volumes. It aims to provide advice in patient selection for STAR including etiology specific aspects, and advice in optimal cardiac target volume identification based on available evidence. Safety concerns and the advice for acute and long-term monitoring including the importance of standardized reporting and follow-up are covered by this document. Areas of uncertainty are listed, which require high-quality, reliable pre-clinical and clinical evidence before expansion of STAR beyond clinical scenarios in which proven therapies are ineffective or unavailable.

Distribution and Determinants of Anterior Chamber Angle and Anterior Chamber Volume in Young Chinese Adults

ABSTRACT Purpose Current study aimed to understand the distribution and determinants of anterior chamber angle (ACA) and anterior chamber volume (ACV) in Chinese young adults, which can help fill current data gaps and aid in early detection and intervention for high-risk population of primary angle closure glaucoma. Methods This cross-sectional study utilized data from 2014 participants who completed questionnaire and eye examination in September 2021. ACV and ACA were measured using a Pentacam tomographer. Spherical equivalent (SE) was evaluated by autorefractor without cycloplegia. Central corneal thickness (CCT) and biomechanically corrected intraocular pressure (bIOP) were evaluated using Corvis-ST. Axial length (AL), corneal radius (CR), anterior chamber depth (ACD), and white to white were assessed using the IOL Master. Results A total of 1635 students were included in the analysis. The mean ACV and AVA were 194.74 ± 32.30 μL and 38.81 ± 4.84°, respectively. Males have a larger ACV and wider ACA than females. ACV was positively correlated with ACA (r = 0.24, p < 0.001), and the correlation was stronger for non-myopic students than for myopic students. Multivariable linear regression model showed that AL (β = 2.41), CR (β = –4.12), CCT (β = –0.11), ACD (β = 97.93), and bIOP (β = 0.40) were associated with ACV, and CCT (β = –0.01), CR (β = 0.38), and ACD (β = 7.41) were associated with ACA (all p < 0.05). Random forest model indicated that ACD was the most critical predictor of both ACV and ACA. Conclusions This study reported the distribution and determinants of ACA and ACV. Deeper ACD was associated with larger ACV and wider ACA.

Pronounced neonatal breast enlargement beyond the first week of life and its regression correlates with serum prolactin levels- a case series.

Mild breast swelling is frequently observed in newborns during the first postnatal week. Breast enlargement is also observed in a minor proportion of infants beyond the first postnatal week, leading to discussions how to deal with it. Our objective was to review a case series of infants with prolonged breast swelling. We examined five infants with pronounced breast enlargement beyond the first postnatal weekand measured human chorionic gonadotropin (HCG), estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), and progesterone (P4) in blood samples and analyzed breast volume by sonographic volume determination in all infants initially and across time. The regression of breast enlargement positively correlated with serum prolactin levels in infants with breast enlargement beyond the first week of life. Complete regression occurred after several weeks and was characterized by normalization of serum prolactin levels. The present study emphasizes the role of prolactin in neonates with pronounced breast enlargement beyond the first week of life.

All-optical method to directly measure the pressure–volume–temperature equation of state of fluids in the diamond anvil cell

We have developed a new all-optical method to directly measure the pressure–volume–temperature (PVT) equation of state (EOS) of fluids and transparent solids in the diamond anvil high pressure cell by measuring the volume of the sample chamber. Our method combines confocal microscopy and white light interference with a new analysis method, which exploits the mutual dependence of sample density and refractive index: Experimentally, the refractive index determines the measured sample chamber thickness (and therefore the measured sample volume/density), yet the sample density is by far the dominant factor in determining the variation in the refractive index with pressure. Our analysis method allows us to obtain a set of values for the density and refractive index, which are mutually consistent and agree with the experimental data within error. We have conducted proof-of-concept experiments on a variety of samples (H2O, CH4, C2H6, C3H8, KCl, and NaCl) at ambient temperature and at high temperatures up to just above 500 K. Our proof-of-concept data demonstrate that our method is able to reproduce known fluid and solid EOS within error. Furthermore, we demonstrate that our method allows us to directly and routinely measure the PVT EOS of simple fluids at GPa pressures up to, at least, 514 K (the highest temperature reached in our study). A reasonable estimation of the known sources of error in our volume determinations indicates that the error is currently ±2.7% at high temperature and that it is feasible to reduce it to ca. ±1% in future work.

Urban impervious cover characterization for rainfall-runoff analysis: Impacts of data availability and resolution

Urban watershed hydrologic and water quality models, and stormwater control measure (SCM) designs, rely on accurate determination of stormwater runoff volume and impervious areas contributing to runoff. This research assesses the impacts of data availability and spatial resolution on two of the main indicators of urban impervious cover: total impervious area (TIA) and directly connected impervious area (DCIA). The research also explores the relationship between TIA, DCIA, and the effective impervious area (EIA), another important indicator of urban impervious cover. Using spatial programming, surface runoff was tracked, from originated to discharged locations, in nine urban catchments (ranging from 16 to 2035 ha) in Minnesota, USA, under various scenarios combining geospatial data types and resolutions. TIA fractions derived from low-resolution, nationally available imperviousness data were not statistically different than those from high-resolution land cover (LC) data modified by “unshading” to remove tree canopies overlaying impervious surfaces. Comparison of DCIA and EIA values indicated that modified LC is preferable for accurate DCIA delineation in ungauged catchments. EIA was 65 % of DCIA under the assumption that all rooftops were connected to sewer systems, while it exceeded DCIA by 34 % assuming all rooftops were unconnected, underscoring the importance of rooftop connectivity information in urban areas. The assumption of 0 % to 40 % rooftop connectivity resulted in comparable DCIA and EIA values in the study catchments. Using roads as the runoff collection system (instead of sewer inlets) did not significantly alter DCIA values at 5 % level, when unshaded LC was used. Given the absence of observed runoff data in most urban areas, DCIA serves as an appropriate imperviousness indicator for determining runoff in ungauged urban watersheds. However, achieving accurate DCIA delineation necessitates high-resolution LC data, emphasizing the need for relevant urban management organizations to develop such data.