Pressure Calibration Research Articles

Reliability and validity of low cost pressure gauge manometer for measurement of respiratory muscle strength in healthy children: a cross-sectional study

Background: Assessing respiratory muscle strength is an important aspect for clinical practice as well as in research. Multiple factors such as health status of an individual, level of physical fitness and postsurgical recovery of an individual have an influence on respiratory biomechanics. Respiratory muscle strength is determined by measuring maximal inspiratory pressure and maximal expiratory pressure. There is a need for a cost effective, portable, easy to build device specifically to estimate respiratory muscle strength. There is insufficient literature regarding the resources used to determine the respiratory muscle strength testing in children, hence this study aims to establish the reliability and validity of low cost pressure gauge manometer which could be a useful tool in measuring respiratory muscle strength in children. Methods: A capsule sensing pressure gauge constructed according to the American thoracic society guidelines with a calibration of pressure between −200 cmH2O to +200 cmH2O. It was used to measure the respiratory muscle strength. The study was conducted on 300 healthy children. Results: SPSS software was used for statistical analysis. Reliability of 0.92 and 0.97 was obtained for MIP and MEP respectively by test retest method. Construct validity index showed a validity score of 0.8 for MIP and MEP. Conclusions: The results indicate that the low cost pressure gauge manometer can be used as a reliable and valid device to measure respiratory muscle strength in children.

Measurement uncertainty analysis of sound intensity using double-coupler calibration system

Currently, sound intensity instrument calibrations consist of a paired microphone phase and pressure calibrations, and the general uncertainty analysis focuses on how to calculate and express the uncertainty in the pressure lever and phase difference. However, no guidance for intensity level uncertainty is available. A significant barrier is the requirement to develop a measurement model that constitutes a relationship between the output quantities and input quantities, known to be the paired microphone pressure levels and phase difference. The Beijing Aerospace Institute of Metrology and Measurement Technology (AIM) is addressing this issue using a double-coupler calibration system, which is the incentive for the systematic evaluation of the associated measurement uncertainty in this study. A set of methodologies based on the plane-wave model is developed for estimating intensity and particle velocity uncertainty for sound intensity instruments.

Calibration of local chemical pressure by optical probe.

Chemical stabilization of a high-pressure metastable state is a major challenge for the development of advanced materials. Although chemical pressure (Pchem) can effectively simulate the effect of physical pressure (Pphy), experimental calibration of the pressure passed to local structural motifs, denoted as local chemical pressure (Pchem-Δ) which significantly governs the function of solid materials, remains absent due to the challenge of probing techniques. Here we establish an innovative methodology to experimentally calibrate the Pchem-Δ and build a bridge between Pchem and Pphy via an optical probe strategy. Site-selective Bi3+-traced REVO4 (RE=Y, Gd) is adopted as a prototype to introduce Bi3+ optical probes and on-site sense of the Pchem-Δ experienced by the REO8 motif. The cell compression of RE0.98Bi0.02VO4 under Pphy is chemically simulated by smaller-ion substitution (Sc3+ → RE3+) in RE0.98-xScxBi0.02VO4. The consistent red shift (Δλ) of the emission spectra of Bi3+, which is dominated by locally pressure-induced REO8 dodecahedral variation in RE0.98Bi0.02VO4 (Pphy) and RE0.98-xScxBi0.02VO4 (Pchem-Δ), respectively, is evidence of their similar pressure-dependent local structure evolution. This innovative Δλ-based experimental calibration of Pchem-Δ in the crystal-field dimension portrays the anisotropic transmission of Pchem to the local structure and builds a bridge between Pchem-Δ and Pphy to guide a new perspective for affordable and practical interception of metastable states.

New methods to reconstruct paleo-oil and gas compositions and P-T trapping conditions of hydrocarbon fluid inclusions in sedimentary basins

Accurate predictions of fluid composition and P-T trapping condition of hydrocarbon fluid inclusions (HFIs) is crucial to understand complex oil and gas charging history and accumulation mechanism. However, traditional P-T prediction methods are not enough powerful to get reliable results because of difficulty in direct composition measurement and great uncertainties in indirect composition prediction for single HFI. In this study, we collected 296 crude oil and 983 gas condensate fluids to develop new composition and trapping pressure (Pt) prediction models. Based on the measured fluid composition, saturation pressure (corresponding to homogenization pressure, Ph) and volume data, we firstly calibrate the Ph, the degree of bubble filling (Fv, at 20 °C) and isochores predictions for the measured fluids through matching saturation pressure and volume calibration and then established a standard fluid database with fluid composition, Ph, Fv and Pt. For the first time, a new hydrocarbon fluid composition prediction model was developed which is only function of Fv and homogenization temperature (Th) of HFIs. The new composition model allows directly predicting the entire fluid compositions from methane (C1) to heptane plus (C7+) fractions in HFI based on Fv and Th. Furthermore, we developed different Pt prediction models for varying fluid compositions and phase states of HFIs. For oil-bearing fluid inclusions which homogenize into liquid phase (OFIL) methane molar content is the only variable that is needed to predict Pt with a high degree of accuracy (8.2–12.3% for average absolute deviation, AAD). However, for gas condensate-bearing fluid inclusions (GCFI), more composition (C1–C7+) together with the physical property (molecular weight and specific gravity) of C7+ composition must be incorporated into the prediction model to obtain a better prediction accuracy of Pt. The new Pt prediction models give prediction accuracy of 11.2–17.6% (AAD) for GCFIL (homogenizing into liquid phase), and 15.9–22.8% (AAD) for GCFIG (homogenizing into gas phase). Our new composition and Pt prediction models can give the best and fastest predictions of hydrocarbon fluid composition and trapping condition and are of great significance for petroleum charging history reconstruction in sedimentary basins.

Equation of state of KI up to 150 GPa

ABSTRACT The equation of state of potassium iodide, KI, has been determined up to 156 GPa at 298 K by angular-dispersive X-ray diffraction in diamond-anvil-cell. Helium pressure transmitting medium was used to minimize non-hydrostatic stress on the sample. The B2 phase is stable at least between 2 and 156 GPa. Pressure–volume data were fitted using a Rydberg–Vinet equation of state. The volume, isothermal bulk modulus and its pressure derivative of B2-KI at ambient pressure are , GPa and . It allows using KI as a pressure calibrant in high pressure experiments.

Refined room-temperature equation of state of Bi up to 260 GPa

At room temperature, bismuth undergoes several structural transitions with increasing pressure before taking on a body-centered cubic (bcc) phase at approximately 8 GPa. The bcc structure is stable to the highest measured pressure and its simplicity, along with its high compressibility and atomic number, makes it an enticing choice as a pressure calibrant. We present three data sets on the compression of bismuth in a diamond anvil cell in a neon pressure medium, up to a maximum pressure of about 260 GPa. The use of a soft pressure medium reduces deviatoric stress when compared to previous work. With an expanded pressure range, a higher point density, and a decreased uniaxial stress component, we are able to provide more reliable equation of state parameters. We also conduct density functional theory electronic-structure calculations that confirm that the bcc phase is energetically favored at high pressure.

Synergistic luminescence effect and high-pressure optical properties of CsPbBr2Cl@EuMOFs nanocomposites.

Metal-organic frameworks (MOFs) are a class of highly porous materials that have garnered significant attention in the field of optoelectronics due to their exceptional properties. In this study, CsPbBr2Cl@EuMOFs nanocomposites were synthesized using a two-step method. The fluorescence evolution of the CsPbBr2Cl@EuMOFs was investigated under high pressure, revealing a synergistic luminescence effect between CsPbBr2Cl and Eu3+. The study found that the synergistic luminescence of CsPbBr2Cl@EuMOFs remains stable even under high pressure, and there is no energy transfer among different luminous centers. These findings provide a meaningful case for future research on nanocomposites with multiple luminescent centers. Additionally, CsPbBr2Cl@EuMOFs exhibit a sensitive color-changing mechanism under high pressure, making them a promising candidate for pressure calibration via the color change of the MOF materials.

OSCA-finder: Redefining the assay of kidney disease diagnostic through metabolomics and deep learning

Liquid chromatography-mass spectrometry (LC-MS) is a platform for urine and blood sample analysis. However, the high variability in the urine sample reduced the confidence of metabolite identification. Therefore, pre and post-calibration operations are inevitable to ensure an accurate urine biomarker analysis. In this study, the phenomenon of a higher creatinine concentration variable in ureteropelvic junction obstruction (UPJO) patient urine samples than in healthy people was revealed, indicating the urine biomarker discovery of UPJO patients is not adapted to the creatinine calibrate strategy. Therefore, we proposed a pipeline “OSCA-Finder” to reshape the urine biomarker analysis. First, to ensure a more stable peak shape and total ion chromatography, we applied the product of osmotic pressure and injection volume as a calibration principle and integrated it with an online mixer dilution. Therefore, we obtained the most peaks and identified more metabolites in a urine sample with peak area group CV<30%. A data-enhanced strategy was applied to reduce the overfit while training a neural network binary classifier with an accuracy of 99.9%. Finally, seven accurate urine biomarkers combined with a binary classifier were applied to distinguish UPJO patients from healthy people. The results show that the UPJO diagnostic strategy based on urine osmotic pressure calibration has more potential than ordinary strategies.

WHICH SYSTOLIC BLOOD PRESSURE SHOWS CLOSEST ASSOCIATIONS WITH LEFT VENTRICULAR MASS? THE INTERNATIONAL 24 HOUR AORTIC BLOOD PRESSURE CONSORTIUM (I24ABC)

Objective: Central systolic blood pressure (cSBP) may be closer associated with hypertensive organ damage, namely left ventricular mass (LVM) and hypertrophy (LVH), as compared to brachial SBP (bSBP), and 24hour ambulatory SBP may be closer associated with LVM and LVH, as compared to office SBP. We sought to address this by pooling data from 21 centers worldwide. Design and method: In all centers, bSBP and cSBP was measured with the same validated oscillometric upper arm device (Mobil-O-Graph, I.E.M., Germany), using a transfer function for central pressure, and systolic/diastolic pressure (cSBPC1) or mean/diastolic pressure (cSBPC2) calibration. LVM was determined by echocardiography, and indexed to body surface area (LVMi). Results: We studied 2367 participants (45.5% women), 31.3% treated with antihypertensives. Mean age of 50.8 years (range 10-104 years). Average brachial office BP was 137/89 mm Hg, average brachial 24hour BP was 126/80 mm Hg. Average LVMi was 89.9 g/m2, and 24.1% had LVH. The correlation coefficients between LVMi and office bSBP, office cSBPC1, office cSBPC2, 24hour bSBP, 24hour cSBPC1, and 24hour cSBPC2 were 0.21, 0.20, 0.29, 0.31, 0.29, and 0.38, respectively. Based on z-statistics, the relationship between LVMi and office /24hour cSBPC2 was closer than with the other office/24hour SBPs (p = 0.0001 and 0.0002 for comparison with bSBPs, respectively). These findings were consistent in men and women, across all age groups, in lean, overweight and obese individuals, and in individuals with or without antihypertensives. In ROC analysis, the area under the curve (AUC) for detection of LVH was 0.626, 0.632, 0.668, 0.659, 0.653, and 0.687 for office bSBP, office cSBPC1, office cSBPC2, 24hour bSBP, 24hour cSBPC1, and 24hour cSBPC2, respectively – Figure). The AUC for office/24hour cSBPC2 was significantly larger, as compared to office/24hour bSBP (p &lt; 0.0001 for both comparisons). Conclusions: In a large international research consortium, we observed that 24hour cSBP, measured with an oscillometric cuff, shows a significantly closer association with hypertensive cardiac organ damage than the related brachial SBPs. In addition, the method of waveform calibration is crucial.

Combined Interrogation Algorithm of Phase Function and Minimum Mean Square Error for Fiber-Optic Fabry-Perot Micro-Pressure Sensors Based on White Light Interference

In this paper, a demodulation algorithm using the phase function of the Fabry-Perot (FP) cavity combined with the minimum mean squared error (MMSE) is proposed for the pressure measurement with low-pressure sensitivity fiber-optic FP micro-pressure sensors, which exhibits reasonable demodulation results. In this algorithm, the initial phase variation during the measurement process is focused, which is usually disregarded in traditional demodulation, and then, use the phase change features of phase function to achieve precise pressure demodulation. A functional relation between the reference pressure and the amount of phase function displacement is developed for demodulation based on interferometric spectra of reference pressures at 0 kPa and 35 kPa. The algorithm has been investigated theoretically and experimentally. The experiment results demonstrate that the measurement accuracy is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula> 0.2 kPa in the pressure measurement range from 0 kPa to 35 kPa, the pressure resolution is up to 0.0218 kPa, and the reading error is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm 3\%$</tex-math></inline-formula> in the pressure range from 6.7 kPa to 35 kPa, which indicate that the proposed algorithm can meet medical pressure analysis standards in the cardiovascular sector for low-pressure sensitivity sensors. Moreover, this work illustrates that inaccurate reference pressure calibration would cause substantial demodulation errors. These errors can be mitigated by appropriately increasing the number of reference pressures to keep the reading error at a reasonable level according to the specific application.

Aluminum Nitride Piezoelectric Micromachined Ultrasound Transducer Arrays for Non-Invasive Monitoring of Radial Artery Stiffness

An aluminum nitride (AlN) piezoelectric micromachined ultrasound transducer (PMUT) array was proposed and fabricated for non-invasive radial artery stiffness monitoring, which could be employed in human vascular health monitoring applications. Using surface micromachining techniques, four hexagonal PMUT arrays were fabricated within a chip area of 3 × 3 mm2. The mechanical displacement sensitivity and quality factor of a single PMUT were tested and found to be 24.47 nm/V at 5.94 MHz and 278 (in air), respectively. Underwater pulse-echo tests for the array demonstrated a -3 dB bandwidth of 0.76 MHz at 3.75 MHz and distance detection limit of approximately 25 mm. Using the PMUT array as an ultrasonic probe, the depth and diameter changes over cardiac cycles of the radial artery were measured to be approximately 3.8 mm and 0.23 mm, respectively. Combined with blood pressure calibration, the biomechanical parameters of the radial artery vessel were extracted using a one-dimensional vascular model. The cross-sectional distensibility, compliance, and stiffness index were determined to be 4.03 × 10-3/mmHg, 1.87 × 10-2 mm2/mmHg, and 5.25, respectively, consistent with the newest medical research. The continuous beat-to-beat blood pressure was also estimated using this model. This work demonstrated the potential of miniaturized PMUT devices for human vascular medical ultrasound applications.

Dynamic pressure surface deformation measurement based on a chromatic confocal sensor.

To enable the real-time measurement of pressure deformations in sealed cavities, a high-precision method of detecting the deformation of a material surface is proposed. By combining a chromatic confocal displacement sensor with a pressure sensor, we can acquire dynamic online strain measurements that consider the effects of the deformed material and internal environmental conditions. A 90m m×90m m static mechanical cylindrical cavity is simulated using finite element software. The interior of the cylindrical cavity is continuously pressurized at up to 400kPa with a material deformation of 300µm. We experimentally obtain the spectral peak wavelengths corresponding to the surface deformation experiment, record the spectral data at 20kPa intervals, and use the Voigt fitting algorithm to reduce sensor errors. The results show that the experimental results differ from the simulated results by 1.43µm, with a relative error of 0.083% after sequential pressurization and depressurization using a pressure calibrator, and the uncertainty error of pressure deformation measurement is 1.495µm. Thus, the proposed method is robust against external disturbances and is suitable for micrometer-level surface deformation monitoring, which has numerous applications in the high-precision inspection industry.

An investigation on source identification of very high frequency sounds radiated from home appliances around us.

We investigated the azimuth angle characteristics of head related transfer function (HRTF) at very high frequency region using two kinds of head and torso simulators (HATS). In the measurement of hearing thresholds, there are two ways using a headphone or a loudspeaker. In general, it will be carried out using a loudspeaker because sound pressure calibration and measurement are simple. However, the hearing threshold which measured using a loudspeaker at very high frequency region may contain some errors because sound pressure level (SPL) reaching the ear are seriously affected by a small movement of the head. Also, the SPL near the pinna seriously depends on both shapes of a pinna and a head because excess attenuation by diffraction of VHF sound is very large. To provide assurance for the accuracy measurement of hearing threshold, it is important to make clear the relationship between the SPL and shape of head and/or ear. In this paper, we reported the HRTFs calculated from the SPLs measured at three different positions of left ear - a tragus, an auricle and an eardrum and discussed the influence of head and/or ear of HATS from the azimuth angle characteristics of these HRTFs.

Brachial Blood Pressure Invasively and Non-Invasively Obtained Using Oscillometry and Applanation Tonometry: Impact of Mean Blood Pressure Equations and Calibration Schemes on Agreement Levels

The use of oscillometric methods to determine brachial blood pressure (bBP) can lead to a systematic underestimation of the invasively measured systolic (bSBP) and pulse (bPP) pressure levels, together with a significant overestimation of diastolic pressure (bDBP). Similarly, the agreement between brachial mean blood pressure (bMBP), invasively and non-invasively measured, can be affected by inaccurate estimations/assumptions. Despite several methodologies that can be applied to estimate bMBP non-invasively, there is no consensus on which approach leads to the most accurate estimation. Aims: to evaluate the association and agreement between: (1) non-invasive (oscillometry) and invasive bBP; (2) invasive bMBP, and bMBP (i) measured by oscillometry and (ii) calculated using six different equations; and (3) bSBP and bPP invasively and non-invasively obtained by applanation tonometry and employing different calibration methods. To this end, invasive aortic blood pressure and bBP (catheterization), and non-invasive bBP (oscillometry [Mobil-O-Graph] and brachial artery applanation tonometry [SphygmoCor]) were simultaneously obtained (34 subjects, 193 records). bMBP was calculated using different approaches. Results: (i) the agreement between invasive bBP and their respective non-invasive measurements (oscillometry) showed dependence on bBP levels (proportional error); (ii) among the different approaches used to obtain bMBP, the equation that includes a form factor equal to 33% (bMBP = bDBP + bPP/3) showed the best association with the invasive bMBP; (iii) the best approach to estimate invasive bSBP and bPP from tonometry recordings is based on the calibration scheme that employs oscillometric bMBP. On the contrary, the worst association between invasive and applanation tonometry-derived bBP levels was observed when the brachial pulse waveform was calibrated to bMBP quantified as bMBP = bDBP + bPP/3. Our study strongly emphasizes the need for methodological transparency and consensus for non-invasive bMBP assessment.

Application of the method of ordinary least squares in the calibration of temperature, pressure and mass meters

The goal of this paper is applied the Ordinary Least Squares (OLS) method as a strategy in order to reduce the uncertainty measurement associated to the relevant physical quantities. Methodology or method: This work was motivated due to the efforts made in the measurement sciences to investigate alternative methods that allow obtaining greater metrological reliability of the results, that is, reducing the uncertainty associated with the measurement. Thus, the applied methodology consisted of the development of a computational code using the MatLab tool, in which an algorithm was programmed that supports the application of the OLS method. Three of the most used physical magnitudes at an industrial level were evaluated: temperature, pressure and mass. These magnitudes were evaluated from the calibration of three measuring instruments: thermistor, manometer and digital scale. Results: The applied methodology allowed to: (i) obtain the matrix of the coefficients for polynomials of degrees 1, 2, 3 and 4 that adjust the experimental data; (ii) to draw the calibration curves for each of the obtained polynomials and (iii) to estimate the fit uncertainty (i.e.: the mean squared deviation) to specify the polynomial that best models the experimental data for a reliability level of 95.45 % (k = 2). The consolidated results confirmed a reduction in the uncertainty associated with the adjustment polynomial of 99.8% for the temperature measurement, 45.6% for the pressure measurement and 53.9% for the mass measurement. Conclusions: Finally, a discussion of the results is presented, confirming the effectiveness of the ordinary least squares method as a strategy to reduce the uncertainty associated with the calibration of measuring instruments.

On the creation of thermal equations of state for use in Dioptas

ABSTRACT Dioptas is a widely used software package for integrating and analysing 2-dimensional diffraction images. To help interpret the integrated diffraction profiles it produces, Dioptas users can input files that parameterise a material's thermal equation of state (EoS), enabling the positions of the Bragg peaks from that material to be calculated as a function of pressure and temperature. However, care is needed to ensure that these input files correctly describe the thermal EoS of interest. Here we describe the thermal EoS model used by Dioptas and show how existing thermal EoS should be reparameterised so as to be used correctly in Dioptas. Input EoS files suitable for use with Dioptas are provided for the following commonly-used pressure calibrants and pressure transmitting media: Al, Au, Cu, Mo, Nb, Pt, Ta, hcp-Fe, MgO, NaCl-B1, NaCl-B2, KCl-B2, and Ne.

Design and development of mechanical test bench for testing and calibration of multiple blood pressure measuring devices.

Blood pressure (BP) measurement is an important physiological parameter for human health monitoring, which plays a significant role in the diagnosis of many incurable diseases. However, due to inaccuracies in the different types of BP measuring devices, the calibration of these BP measuring instruments is a major concern for a medical practitioner. Currently, these devices' calibration, testing, and validation are performed using rigorous methods with complex clinical trials and following the available documentary standards. This article describes the design and development of an indigenous mechanical test bench (MTB) system for the testing and calibration of multiple BP devices, as per International Organization of Legal Metrology (OIML) recommended documents e.g., OIML R 16-1 and OIML R 16-2. The developed system can test and calibrate 20 BP devices, simultaneously. The traceability of the developed MTB is established by performing its calibration against the Air Piston Gauge, a national primary vacuum standard. The estimated expanded measurement uncertainty evaluated is found to be ±0.11mmHg, which is almost one order better than the measurement uncertainty required for the test and calibration of BP measuring instruments as per standard. The MTB has successfully been used to test and calibrate several BP measuring instruments. The data of one such device is reported herein as an indicator of the performance process. The calibration of these BP measuring instruments was performed in the static mode, and the estimated expanded measurement uncertainty was found to be ±1.25mmHg. The developed MTB system would prove to be an excellent instrument for calibration laboratories, hospitals, regulatory agencies, and other users to test and calibrate 20 BP measuring devices simultaneously and cost-effectively.

PS-C03-12: FINGER-TO-TOE PULSE WAVE VELOCITY IN RESPONSE TO SITTING POSITION

Objective: Aortic stiffness is a non-traditional risk factor for cardiovascular disease and mortality and is associated with increased central pulse pressure. It is generally measured by carotid-femoral pulse wave velocity (PWV) in a supine position. We hypothesized that, in a sitting position, the additional hydrostatic pressure exerted on the vascular wall could represent a vascular stress test. Two alternative methods can now estimate aortic stiffness and can be used conveniently in different positions: 1) brachial pulse wave analysis approach used by Mobil-O-Graph and 2) transit time approach using finger-to-toe PWV by photoplethysmography with the pOpmetre. The aim of the present study is to determine the impact of postural changes on PWV and central blood pressure estimation using these two distinct methods. Design and method: Central blood pressure and PWV were assessed in 20 healthy subjects using Mobil-O-Graph (PWV-M) and pOpmetre (PWV-pop) in three positions: supine in bed, supine in reclining chair and sitting. Central systolic blood pressure (SBP) was determined by calibration of brachial systolic and diastolic blood pressures by both methods (SBP-M and SBP-pop). Generalized estimating equations were used for analysis. Results: The PWV-M remained relatively constant and generally independent of the position (5.5 ± 1.0, 5.3 ± 1.0 and 5.5 ± 1.0 m/s). While PWV-M and PWV-pop were similar in the supine position (5.5 ± 1.0 vs 5.4 ± 1.3 m/s, P = NS), PWV-pop increased very significantly to 5.9 ± 1.5 m/s in supine in reclining chair position (P = 0.04), and to 9.2 ± 1.7 m/s in sitting position (P &lt; 0.001). Central blood pressure estimation remained similar for SBP-M (110.2 ± 10.3 vs 106.9 ± 10.5 vs 108.8 ± 11.1 mmHg, P = NS) and for SBP-pop (107.7 ± 10.4 vs 110.3 ± 9.6 vs 109.5 ± 9.9 mmHg, P = NS). Conclusions: These results suggest that estimated PWV by brachial pulse wave analysis remains robust independent of position. However, the estimated finger-to-toe PWV by pulse transit time increases remarkably with the imposition of hydrostatic pressure on the vascular wall. We conclude that the finger-to-toe PWV may provide the opportunity to evaluated vascular wall property in a dynamic fashion using postural changes as a stress test.

Final report on the key comparison CCAUV.A-K6

Main textThe key comparison CCAUV.A-K6 has been carried out under the auspices of the Consultative Committee on Acoustics, Ultrasound and Vibration (CCAUV) of the International Committee of Weights and Measures (CIPM). This comparison is concerned with primary pressure calibration of laboratory standard microphones type LS2P. The participating NMI's are HBK-DPLA (Denmark), CENAM (Mexico), GUM (Poland), INMETRO (Brazil), KRISS (Korea), LNE (France), METAS (Switzerland), NMIA (Australia), NMIJ (Japan), NMISA (South Africa), NRC (Canada), UME (Turkey) and VNIIFTRI (Russia). The role of Pilot laboratory was undertaken by LNE (France). The measurements took place between March 2019 and December 2020. Two LS2P microphones were circulated. This report includes the measurement results from the participants, information about their calibration methods, and the analysis leading to the assignment of the Key Comparison Reference Values (KCRV) and Degrees of Equivalence (DoE).To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCAUV, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Evaluation of current and future water demand scenario and hydraulic performance of water distribution systems, a case study for Addis Kidam Town, Ethiopia

The hydraulic performance and future water demand of water distribution networks are major factors affecting the efficiency of water distribution systems throughout the world. Currently, Addis Kidam Town in Ethiopia is facing many water supply challenges. Their existing water distribution system is inadequate experiencing significant water loss, pressure, and flow velocity. All becoming worse with forecast population increases. The main objective of this study was to evaluate the hydraulic performance of the water distribution network considering both the existing water demand, together with forecast future water demand. The study was undertaken in Addis Kidam Town in Ethiopia using static analysis and WaterGEMS V8i software. The data were collected using experiment tests, field observation, focus group discussions, and interviews. Sampling sizes of pipes and junctions of distribution networks were used to evaluate velocity and pressure changes of 12% and 15%, respectively, from high and low-pressure zones. The results of this study indicated that the existing distribution network was designed to supply a population of 8,906; however, the current population was 25,854. The existing system can accordingly not meet current demand. The current system was only supplying 19.5 l/c/d to each family and was only able to supply 45.2% of households. All compounded because water loss of the distribution network was 37.9%. Simulation of existing distribution network at junctions and pipes has both 26.6% and 4.3%, and 2.4% and 29.9% lower pressures and velocities during peak and minimum hourly demand, respectively. Model performance values of RMSE, MAE, R2, and NSE of distribution networks were 0.65, 0.40, 0.96, and 0.82 and 0.56, 0.38, 0.98, and 0.78 during the calibration and validation of pressure, flow, and tank level, respectively. The research recommends a two-phase strategic water distribution system response beginning by upgrading and expanding the water distribution network, to first achieve a supply of 30 l/c/d by 2032, and then lifting this to the 30–80 l/c/d range before 2042. The proposed water management upgrading approach is expected to establish a good water supply for all residential communities of the town facing comparable challenges. In general, this study’s findings showed that the existing water supply system could not meet the present demand, let alone meet future growth demand. The existing modeling highlighted that significant increases in supply are possible by targeting system improvements, together with the need to find additional supply to meet both present and future water demand.