Gravimetric Measurements Research Articles

Estimate of the impact of storm microseisms on long-term gravimetric measurements

This study estimates the impact level of storm microseisms on long-term gravimetric measurements. Gravimetric measurements were conducted at the Zapolskoe, Obninsk, and Murmansk sites using CG-5 Autograv relative gravity meters. Seismic measurements were carried out concurrently with gravimetric measurements at Zapolskoe. The analysis of these measurements demonstrates the feasibility of utilizing seismic data as control information to estimate the high-frequency noise component of gravimetric data. Based on the additional seismic information from the services of the Incorporated Research Institutions for Seismology, the correspondence between the attenuation of the noise component in gravimetric measurements and the data from the modeled sensitive element of the gravimeter, which utilizes seismic series as an input, is identified. The first characterization of the storm-induced background noise of gravimetric measurements at the Murmansk site is obtained. Furthermore, the possibility of predicting measurement errors based on meteorological forecasts is refined, which can aid in the planning of gravimetric work.

Lipid Yields and Fatty Acid Composition if Indigenous Microalgae, Isolated from the Beira, and Diyawanna Urban Lakes, for Sustainable Biofuel Production in Sri Lanka


 Biofuels are carbon-neutral combustibles produced from renewable biomass. Third generation biofuels, derived from microalgal biomass, are distinctly superior to their preceding generations, due to higher productivity and resource use efficiency of microalgae compared to conventional energy crops. It is a viable source of sustainable energy for our country due to the availability of water, ambient temperatures and year-round sunlight needed for microalgae cultivation, and most importantly, the abundance of diverse microalgae species. However, these native microalgae are relatively unexplored for their productivities and thereby, greatly underutilized. This research was aimed to investigate the lipid yields and fatty acid compositions of local freshwater microalgae, and to identify their potential for biodiesel production. This was carried out by (1) microalgae isolation and morphological identification (2) microalgae cultivation (3) biomass harvesting, lipid extraction, gravimetric measurement of extracted lipids and (4) acid-catalysed transesterification, followed by GCMS analysis of the biodiesel product. Chlorella sp., Chlorococcum sp. and Chlamydomonas sp. were isolated from Beira/ Diyawanna Lakes using streak plate technique in solid standard BBM media. They were next cultivated under axenic conditions in liquid standard BBM media under 16: 8 (light: dark), at 25°C for 20 days in duplicates. The biomass was then harvested using alum, dried to reach a constant weight and the Bligh and Dyer lipid extraction was done in triplicate. The extracted lipids were trans-esterified with methanol, using sulfuric acid catalyst at 90° C for 60 minutes. The separated product was analysed by GCMS. Chlorella sp., Chlorococcum sp. and Chlamydomonas sp. cultivated under standard conditions gave average lipid yields of 11.34±1.01%, 15.00±1.40% and 2.10±0.50% respectively. Average lipid yield of Chlamydomonas sp. was significantly lower than the other two species at 95% confidence level (Two-sample T test on SPSS Version 21). GCMS analysis of the biodiesel product from Chlorella sp. indicated significant levels of saturated fatty acids including palmitic and stearic acids, monounsaturated fatty acids like cis-11- eicosenoic acid and polyunsaturated fatty acids including linoleic and linolenic acids. The fatty acid ratios were used to calculate the saturation value, cetane number, density, iodine value and pour point of the produced biodiesel. These quality parameters were in accordance with the ASTM D6751- 20a standards. Therefore, with a substantial yield and fatty acid composition of intracellular lipids, this local species of Chlorella can be a prospective candidate for sustainable bioenergy production in Sri Lanka.
 
 Keywords: Chlorella, Chlorococcum, Chlamydomonas, Microalgal lipids, Biodiesel

In-depth experimental assessment of two new aminocoumarin derivatives as corrosion inhibitors for carbon steel in HCl media combined with AFM, SEM/EDX, contact angle, and DFT/MDs simulations

The suitability of the two synthesized hydrazones namely N''-[(4-aminocoumarin-3-yl)methylidene]thiocarbonohydrazide (AMT), and 2-[(4-Aminocoumarin-3-yl)methylidene]hydrazinecarbodithioic acid (AMH) as corrosion inhibitors for N80 carbon steel (N80 CS) metal in acidic hydrochloric solution has been investigated at different concentrations of inhibitors (10–7 to 10–3 M) and different temperatures (298–328 K). The Inhibition efficiency was examined by gravimetric measurements, electrochemical methods supplemented with AFM, SEM-EDX, contact angle measurement, and XRD. The compounds have been characterized using IR, 1H NMR, 13C NMR, and mass spectra. It was found that AMT and AMH exhibit maximum inhibition efficiency of 90.52 and 93.28 %, respectively, at 10−3M against N80 CS corrosion in 1.0 M HCl solutions. The adsorption of inhibitors on the N80 CS surface tends to obey the Langmuir adsorption isotherm. Potentiodynamic polarization results revealed that AMT and AMH functioned as mixed-type inhibitors. All thermodynamic parameters were estimated and discussed. The combination of density functional theory (DFT) and molecular dynamic simulations was used to understand the sites in the AMT and AMH molecules where interaction with the N80 CS surface can occur. Results of the biological test revealed the excellent bioactivity of the AMT and AMH compounds, suggesting AMT and AMH are environmentally friendly corrosion inhibitors.

Prenatal arsenite exposure alters maternal cardiac remodeling during late pregnancy

Exposure to inorganic arsenic through drinking water is widespread and has been linked to many chronic diseases, including cardiovascular disease. Arsenic exposure has been shown to alter hypertrophic signaling in the adult heart, as well as in utero offspring development. However, the effect of arsenic on maternal cardiac remodeling during pregnancy has not been studied. As such, there is a need to understand how environmental exposure contributes to adverse pregnancy-related cardiovascular events. This study seeks to understand the impact of trivalent inorganic arsenic exposure during gestation on maternal cardiac remodeling in late pregnancy, as well as offspring outcomes. C57BL/6 J mice were exposed to 0 (control), 100 or 1000 μg/L sodium arsenite (NaAsO2) beginning at embryonic day (E) 2.5 and continuing through E17.5. Maternal heart function and size were assessed via transthoracic echocardiography, gravimetric measurement, and histology. Transcript levels of hypertrophic markers were probed via qRT-PCR and confirmed by western blot. Offspring outcomes were assessed through echocardiography and gravimetric measurement. We found that maternal heart size was smaller and transcript levels of Esr1 (estrogen receptor alpha), Pgrmc1 (progesterone receptor membrane component 1) and Pgrmc2 (progesterone receptor membrane component 2) reduced during late pregnancy with exposure to 1000 μg/L iAs vs. non-exposed pregnant controls. Both 100 and 1000 μg/L iAs also reduced transcription of Nppa (atrial natriuretic peptide). Akt protein expression was also significantly reduced after 1000 μg/L iAs exposure in the maternal heart with no change in activating phosphorylation. This significant abrogation of maternal cardiac hypertrophy suggests that arsenic exposure during pregnancy can potentially contribute to cardiovascular disease. Taken together, our findings further underscore the importance of reducing arsenic exposure during pregnancy and indicate that more research is needed to assess the impact of arsenic and other environmental exposures on the maternal heart and adverse pregnancy events.

Migration of plasticizers from flexible PVC: Monitoring the concentration profiles by confocal Raman microspectroscopy

This study introduces and validates an effective approach for monitoring the plasticizer amount and its concentration profile in polyvinyl chloride (PVC) formulations. The method combines gravimetric measurements with confocal Raman depth profiling analysis. Several flexible PVC (pPVC) formulations were compared in this study, including: pPVC@DEHP, using the monomeric plasticizer di(2-ethylhexyl) phthalate (DEHP); pPVC@PBA, using the polymeric plasticizer poly(butylene adipate) (PBA); and crosslinked pPVC (cPVC@DEHP), where isophorone diamine (IPDA) served as the crosslinker. Migration tests were performed according to UNI EN ISO 177 standard. Spectroscopic findings were correlated with gravimetric data, highlighting strong differences in the migration behavior among the formulations. The results demonstrate the effectiveness of the proposed method in quantifying plasticizer leaching and obtaining detailed concentration profiles at fine scale.

Modernization of the basic gravimetric control network Polish Geological Institute – implementing a modern international gravimetric system and relationship with the historical Potsdam system

Abstract The project of the gravimetric database reambulation from the collections of the Central Geological Archives set itself the goal of ending the era of gravimetric bases dualism and transferring both databases: gravimetric base and archival gravimetric semi-detailed measurements to the modern frame of gravity reference, consistent with ITGRS/F definitions and realizations. This will strengthen the interpretational potential of gravimetric data and will open the possibility of fully integrating Polish gravity data with international databases of this type, and will also allow for the performance of modern works in relation to the modern gravimetric control network, i.e., in relation to the highest possible precision of the reference definition of gravimetric measurements in the country. Whenever the article refers to the units in which the gravity vector is determined, milliGal [mGal] is used, and the relation to the SI system is as follows: 1mGal = 10–5ms–2 or microGal [µGal] where 1µGal = 10–8ms–2.

Testing a novel sensor design to jointly measure cosmic-ray neutrons, muons and gamma rays for non-invasive soil moisture estimation

Abstract. Cosmic-ray neutron sensing (CRNS) has emerged as a reliable method for soil moisture and snow estimation. However, the applicability of this method beyond research has been limited due to, among others, the use of relatively large and expensive sensors. This paper presents the tests conducted on a new scintillator-based sensor especially designed to jointly measure neutron counts, muons and total gamma rays. The neutron signal is first compared against two conventional gas-tube-based CRNS sensors at two locations. The estimated soil moisture is further assessed at four agricultural sites, based on gravimetric soil moisture collected within the sensor footprint. Muon fluxes are compared to the incoming neutron variability measured at a neutron monitoring station and total gammas counts are compared to the signal detected by a gamma ray spectrometer. The results show that the neutron dynamic detected by the new scintillator-based CRNS sensor is well in agreement with conventional CRNS sensors. The derived soil moisture also agreed well with the gravimetric soil moisture measurements. The muons and the total gamma rays simultaneously detected by the sensor show promising features to account for the incoming variability and for discriminating irrigation and precipitation events, respectively. Further experiments and analyses should be conducted, however, to better understand the accuracy and the added value of these additional data for soil moisture estimation. Overall, the new scintillator design shows to be a valid and compact alternative to conventional CRNS sensors for non-invasive soil moisture monitoring and to open the path to a wide range of applications.

Determining the accuracy and suitability of common analytical techniques for sophorolipid biosurfactants.

To determine the performance of a sophorolipid biosurfactant production process, it is important to have accurate and specific analytical techniques in place. Among the most popular are the anthrone assay, gravimetric quantification (hexane:ethyl acetate extraction), and high-performance liquid chromatography (HPLC). The choice of analytical tool varies depending on cost, availability, and ease of use; however, these techniques have never been compared directly against one another. In this work, 75 fermentation broths with varying product/substrate concentrations were comprehensively tested with the 3 techniques and compared. HPLC-ultraviolet detection (198nm) was capable of quantifying C18:1 subterminal hydroxyl diacetylated lactonic sophorolipid down to a lower limit of 0.3g/L with low variability (<3.21%). Gravimetric quantification of the broths following liquid:liquid extraction with hexane and ethyl acetate showed some linearity (R2=.658) when compared to HPLC but could not quantify lower than 11.06g/L, even when no sophorolipids were detected in the sample, highlighting the non-specificity of the method to co-extract non-sophorolipid components in the final gravimetric measure. The anthrone assay showed no linearity (R2=.129) and was found to cross-react with media components (rapeseed oil, corn steep liquor, glucose), leading to consistent overestimation of sophorolipid concentration. The appearance of poor biomass separation during sample preparation with centrifugation was noted and resolved with a novel sample preparation method with pure ethanol. Extensive analysis and comparisons of the most common sophorolipid quantification techniques are explored and the limitations/advantages are highlighted. The findings provide a guide for scientists to make an informed decision on the suitable quantification tool that meets their needs, exploring all aspects of the analysis process from harvest, sample preparation, and analysis.

Blood loss quantification during major abdominal surgery: prospective observational cohort study

BackgroundBlood loss during major abdominal surgery is an essential parameter in the evaluation of strategies aimed at reducing perioperative bleeding. However, blood loss quantification remains unreliable and inaccurate. The aim of this study was to compare several methods of blood loss quantification—visual estimation by surgeon and anesthesiologist, the gravimetric method, the calculation method with spectrophotometric measurement. The spectrophotometric measurement is considered as the most accurate method.MethodsThe study was designed as a prospective observational cohort single-center study. We analyzed 61 patients who underwent elective liver or pancreatic resection. The anesthesiologists’ and surgeons' estimate of blood loss was based on a visual assessment. The gravimetric method was based on weighing the suction canister and surgical drapes before and after use. The basis of calculation method was anthropometric and hematological parameters, we used López-Picado's formula. The spectrophotometric method was based on the spectrophotometric determination of hemoglobin mass in the lost blood. We compared the methods using paired t-test, non-parametric Wilcoxon test and Bland–Altman analysis.ResultsVisual estimation by surgeons and anesthesiologists, gravimetric measurement, and calculation method were significantly different from spectrophotometric measurement at the significance level α = 0.05. All methods overestimated blood loss which was measured by spectrophotometric method. The estimate by surgeons was the closest to the spectrophotometric measurement, difference 68.7 ml (95% confidence interval [CI]: -129.3–-8.2).ConclusionsWe conclude that the estimate of blood loss by surgeons and anesthesiologists, as well as gravimetric method and calculation method are all significantly inaccurate in real surgical setting. We did not confirm the commonly accepted assumption that surgeons underestimate the blood loss.Trial registrationThe study was registered under the title " Blood Loss Quantification During Major Abdominal Surgery" at ClinicalTrials.gov with the registration number NCT05316649. Date of the first registration was 20/3/2022.

CORROSION OF CARBON STEEL AND SOME OTHER METALS IN FRESH WATER OF HYDRAULIC STRUCTURES (HS)

Using the method of gravimetric and electrochemical measurements, the corrosion rate of St3 steel in the water basins of the Takhtakerpi and Shemkirchay hydroelectric power stations has been determined. To establish the expected corrosivity of water, the chemical composition and some physicochemical parameters of the above waters have been determined. As a result of long-term measurements carried out over one year, it has established that steel in the water basins of the Takhtakerpi and Shemkirchay hydroelectric power stations corrodes at a rate of 0.04 g/m2 h and (0.07÷0.08) g/m2 h, respectively. And in the atmosphere of these hydroelectric power plants, steel corrodes at a low rate, approximately an order of magnitude lower. Analysis of water taken from these hydroelectric power stations showed a very low content of corrosive ions, the concentration of which, especially in the Shemkirchay reservoir, corresponds to spring water. By taking polarization curves it has been established that the rate of steel corrosion is controlled by the concentration of dissolved oxygen in water

Image Based In-Process Powder Stream Monitoring during Laser Metal Deposition for the Measurement of the Gravimetric Powder Mass Flow Rate and the Detection of Deviations in the Powder Stream

In laser metal deposition, the quality of the applied clad as well as the additively manufactured component is directly linked to the precise powder feeding into the laser-induced melt pool. Despite the highly automated and closely monitored process, there is currently no industrially established in-process system for the powder stream monitoring. In this work, the powder is illuminated with a line laser in a defined horizontal plane to visualize the back-reflecting light to the camera. Optical filtering is needed to attenuate the process emissions, which is adjusted to the wavelength of the illumination laser. The powder stream is continuously monitored by observing grayscale values. The gravimetric measurements of the powder mass flow are correlated to the grayscale values to display the powder mass flow in absolute mass flow values from the image data. This is qualified by the detection of defined and temporarily introduced deviations in the powder stream.

The comparison of different methods of determining the rock density from gravity data

We focus on two methods of determining the density of the rock environment based on gravimetric measurements. The first method, a combined underground-surface approach, relies on recent measurements made at pairs of points along the vertical. One point is located in accessible underground spaces, like tunnels, mine workings, or caves, while the other is on the Earth's surface. The second, surface method, is solely based on the analysis of the Gravimetric Database of the Slovak Republic. Both methods are based on the proportionality between free-air anomalies and the gravitational effect of topographic masses, calculated for unit density. We compare the respective outputs of both methods and attempt to understand the existing differences between them. We also confront the density estimates in question with one of the two existing density maps of Slovakia compiled from density measurements on rock samples. Across a total of 14 measured locations, we observe a relatively wide spectrum of values on the agreement-disagreement scale, ranging from close similarity to relatively significant differences.

Revisiting Open Circuit Corrosion of Cr in Unpurified Molten FLiNaK Salts with a Multi-Modal Approach

Corrosion and mitigation of environmental degradation of structural materials in high-temperature Gen IV molten salt reactors, are critical issues. However, any corrosion studies have historically been forensic post-test examinations and materials development has occurred mainly by trial and error until recently. Meanwhile, a fundamental understanding can only be achieved by recognizing how the corrosion system of model materials in molten fluoride salts evolves as a function of time. A number of in-situ spectroscopy techniques to identify corrosion product compositions in molten salts have been suggested in recent years. Raman, high-temperature UV-Vis absorption spectroscopy, and X-ray absorption spectroscopy are a few of them [1,2]. These techniques' major limitations include the fact that they are mainly qualitative, and complex hardware requiring a beam focusing inside the glove box is needed. At the same time, electrochemical techniques have been presented which can provide the information on behavior of both metal and its corrosion product in the continuously evolving corrosion system in molten salts. However, use of single isolated methods renders it difficult to obtain mechanistic information on instantaneous, time-dependent processes and phenomena during corrosion. These are needs gaps opportunities. In this work we present a detailed electrochemical analysis of the corrosion of polycrystalline chromium at 600°C in FLiNaK over 50 h including an electrochemical analysis of in-situ near-instantaneous corrosion rates corroborated with other methods.A variety of corroborating methods including (1) in-situ electrochemical diagnostic techniques, (2) static immersion exposure with gravimetric and SEM analysis, (3) electrochemical impedance spectroscopy, (4) XRD, (5) ICP-OES, was utilized to study the corrosion behavior in unpurified FLiNaK at 600°C. The focus was to evaluate the viability of using an external non-reactive electrode to measure the concentration of corrosion products via redox process analysis in order to determine the corrosion rate during the process of OCP corrosion of Cr in FLiNaK. This work reports the possibility of using of electrochemical techniques such as CV for the instantaneous determination of Cr corrosion rates when Cr is exposed to a 600oC FLiNaK salts for 50 h. It was found that the concentration of dissolved corrosion products, in the more likely possible forms of CrF3 - and CrF6 3- , might be calculated by established analytical approaches to CV analysis such as Berzins-Delahay (soluble/insoluble) and Randles-Ševcik equations (soluble/soluble). The calculated values showed the definite concentration of Cr(II)/Cr(III) corrosion products at the distance of the external electrode (due to the static corrosion conditions). These finding supported by XRD and ICP-OES. A semi-infinite diffusion model was employed in this study to adjust the calculated concentrations assuming a stagnant solution and diffusion based one-dimensional concentration diffusion profile in order to calculated the Cr(III) concentration at a fixed position in the Cr(III) concentration gradient. It was shown that the semi-infinite diffusion model helps correctly describe this profile between 10 and 50 h, based on the geometry of the working electrode and corrosion cell. Based on these results the OCP corrosion rate was interpreted to switch over 50 h from initially charge transfer control Cr(II) oxidation at early times with likely HF and Cr(III) reduction, followed by mass transport control regulated by a salt film and then possible stifling due to depletion of HF and Cr(III) solubility limits.The results of half-cell redox potentials and peak currents pertaining to oxidation/reduction of Cr corrosion products were correlated to the concentrations of particular Cr species and compared with the results of mass loss experiment and ex-situ ICP-OES of post-exposed FLiNaK. The mass loss of the Cr(II)/Cr(III) metal that was approximated by spatially integrating the concentration profiles at a selected time, and the result of Cr mass loss separately obtained from gravimetric measurements showed a reasonable agreement. Furthermore, the rate of accumulation of Cr ions in the residual FLiNaK salt after 50 h of exposure determined by ICP-OES, correlated with the electrochemical CV and EIS analysis. In addition to this, the oxidation and reduction peak potentials pertaining to Cr/CrF3 - and CrF3 -/CrF6 3- redox reactions (measured on Pt wire) were compared with the OCP (measured on Cr) to provide insights on the predominant anodic and cathodic reactions. Acknowledgments This research was supported as part of the fundamental understanding of transport under reactor extremes (FUTURE), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. Utilization of the Malvern-Panalytical Empyrean diffractometer was supported by Nanoscale Materials Characterization Facility with National Science Foundation under award CHE-2102156. References Y. Liu et al., (2020) Corrosion Science. 169 108636. https://doi.org/10.1016/j.corsci.2020.108636.S. Fayfar, et al., (2022). https://doi.org/10.26434/chemrxiv-2022-3nspm.

Influence of Depth on CO2/CH4 Sorption Ratio in Deep Coal Seams

The present work aims to analyse the influence of present-day burial depths of coal seams on the sorption properties towards CH4 and CO2, respectively. For medium-rank coals located in the southwestern area of the Upper Silesian Coal Basin (USCB), the gravimetric sorption measurements were carried out with pure gases at a temperature of 30 °C. The variability of CO2/CH4 exchange sorption and diffusivity ratios was determined. It was revealed that in coal seams located at a depth above 700 m, for which the sorption exchange ratio was the greatest, the process of CO2 injection for permanent storage was more beneficial. In the coal seams lying deeper than 700 m with a lower CO2/CH4 sorption ratio, the CH4 displacement induced by the injection of CO2 (CO2-ECBM recovery) became more favourable.

Water Clustering in Polyvinyl Butyral (PVB): Evidenced by Diffusion and Sorption Experiments.

Polyvinyl butyral (PVB) is a transparent amorphous polymer often used to protect fragile surfaces such as glass or photovoltaic panels. The polymer is then packaged in the form of adhesive sheets and bonded to the surfaces. The transport and retention of water in PVB are crucial properties to understand as they modulate the polymer's adhesion properties. In this work, we propose a detailed experimental study of water diffusion and sorption in PVB over a wide range of temperatures and humidity levels in the surrounding atmosphere. Using spectroscopic and gravimetric measurements, our study elucidates how the diffusion coefficient varies with temperature or vapor concentration and provides the activation energy for this process. In addition, dynamic vapor sorption experiments reveal (i) a strong dependence of sorption on hydroxyl group (-OH) concentration and (ii) that the solubility of vapor in PVB decreases with temperature. This enables us to trace the heat of the solution of water in PVB. A comparison of the thermodynamic data obtained with those for water in volume and with the engaged species induced clustering model supports the microscopic view of water organization in PVB in the form of clusters induced by hydrogen bonding.

Intriguing properties of graphite/polysiloxane composite-based pencil electrodes

Pencil leads can be considered well-defined and cheap graphite electrodes for a wide range of electrochemistry applications. These electrodes display many intriguing properties; however, the origin of these properties is not clear. Using various analytical approaches applied to two different commercially available Tombow (TO) and Staedtler (ST) pencils we reveal a causal relationship between the unique properties of pencils and their graphite/polysiloxane composite. We explore the impact of chloroform etching on chemical composition changes, thermal stability and electrochemical parameters of pencils. Using a combination of X-ray photoelectron spectroscopy (XPS) and gas chromatography-mass spectrometry (GC-MS/MS) various polydimethylsiloxanes in composites are revealed. The polysiloxane species leave into the chloroform solvent during the etching resulting in a significant decrease of their content within the electrodes. Differential scanning calorimetry (DSC) data, corroborated by gravimetric measurements, provide additional proof of the presence of composite structures in ST and TO pencils, showing glass transition temperatures at around 76 °C and 81 °C. The main difference between the TO and ST electrodes is the content and composition of the polysiloxanes within the graphite matrix. ST composites have significantly higher polymer content (∼ 30 %) with traces of Na and S impurities compared to TO ones (∼ 14 %) free of contaminations. Furthermore, mainly cyclic nanostructures appear in chloroform extracts of ST composites whereas rather chain-like clusters are liberated out of the TO counterparts. Complementary electrochemical experiments using cyclic voltammetry (CV), impedance spectroscopy (EIS) and the less known elimination voltammetry with linear scan (EVLS) reflect the performance superiority of TO electrodes with much lower polysiloxane content and free of impurities. High conductivity, low capacitive current along with favoured charge carrier transfer all promise a wide range of technological applications for the TO pencil material.

ANALYSIS OF METHODOLOGICAL ERRORS OF THE AVIATION GRAVIMETRIC SYSTEM WITH A TRANSFORMATON GRAVIMETER

The equations of motion and a list of the main components of the AGS are given: gravimeter, stabilization system, system for determining navigation parameters, height meter, on-board digital computer. An analysis of methodological errors of the aviation gravimetric system with a transformer gravimeter was carried out, from which the accuracy requirements for the AGS components were formulated, provided that the accuracy of PST measurements is 1–2 mGal Analytical expressions were found and the coefficients of sensitivity of the total error of the AGS output signal to the measurement errors of the following aircraft movement parameters were calculated: speed, course, latitude, altitude, vertical speed, vertical acceleration, path for different flight modes. Therefore, the study of the sensitivity of the AGS to errors in the measurement of speed, latitude and course, depending on a number of parameters of the aircraft movement, showed that in the case of aviation gravimetric measurements along the Earth’s meridian, it is necessary to accurately determine the course, along the Earth’s parallel – to accurately measure the speed, in mid-latitudes – latitude . It is substantiated that the use of a new two-channel transformer gravimeter provides the necessary increase in the accuracy of AGS. Changes in the sensitivity of the error of the AGS output signal to speed measurement errors were studied depending on the latitude of the site at constant values of the course, as well as on the course of the aircraft at constant values of the latitude. It is shown that the sensitivity of the AGS to speed measurement errors is maximum for the east and west courses (22.6 mGl/m/s and – 6.5 mGl/m/s, respectively) at the location latitude j= 00; minimum for north and south courses and at j=900 regardless of the course (8.05 mGl/m/s). Permissible values of errors in determining the flight parameters of the aircraft were calculated: speed 0.05…0.15 m/s, heading 1.43…3 arcmin, latitude 0.5…1.5 arcmin. min., height 3.3…10 m, vertical speed (0.5…1).102 m/s, vertical acceleration (1…3).10-5 m/s2, path (1.5…4.5) m.

Mechanical cleaning of food soil from a solid surface: A tribological perspective

In this work, a tribological approach was used to distinguish the synergistic effects of mechanical removal and chemical removal (i.e. dissolution) of a layer of representative food soil from a solid surface, using a tribometer, Mini Traction Machine (MTM). Gravimetric and wear measurements of the soil were used to calculate the cleaning rates of burnt tomato puree on a stainless-steel disc, and the corresponding frictional characteristics offers insight of the mechanical removal. The cleaning due to soil dissolution (chemical removal) was quantified by UV–Vis measurements. The overall cleaning rates of food soil featured a linear reduction in mass over time, with a scaled removal rate k = 0.0046 s−1 (5 N applied force and 100 mm s−1 relative velocity), for most cases studied. It was observed that the cleaning rate can be improved with an increasing mechanical load or speed (50% from 1 to 2.5 N and 13% from 50 to 100 mm s−1), but is independent of the initial mass. UV–Vis measurements show that by increasing the load or speed the removal of chunks of burnt tomato puree was enhanced more than removal attributed to dissolution. Similar values of cleaning rates for most experimental parameters were extracted from both the gravimetric and wear measurements. Adhesion and cohesion measurements of the burnt tomato puree were conducted with a micromanipulator. It was found that adhesion forces are higher than cohesion for short soaking times, but for longer times the adhesion forces became weaker and with the additional shear rate in the MTM cleaning experiment, adhesion failure was observed in many cases by the end of the experiment. Indentation measurements showed the change in mechanical properties of the food foulant with a few minutes of soaking in water.

Results of Estimating the Absolute Gravimetric Measurements at the Ledovo Fundamental Gravity Station and on the First Order Gravimetric Network of Russia

Results of Estimating the Absolute Gravimetric Measurements at the Ledovo Fundamental Gravity Station and on the First Order Gravimetric Network of Russia

On the reduction of geodetic and gravimetric measurements on technogenic and geodynamic polygons

On the reduction of geodetic and gravimetric measurements on technogenic and geodynamic polygons