Typical Values Research Articles

INVESTIGATION OF DYNAMICS OF A PIPE ROBOT WITH SELF-STOPPING MECHANISM

Pipe robots are used in agricultural engineering for transportation of various materials inside the pipe as well as for cleaning of internal surfaces of the pipes.
 In this paper a model of a pipe robot with self-stopping mechanism is proposed and described in detail. Numerical investigations are performed, and the obtained results are presented in the form of graphical relationships. Variations of displacements as well as variations of velocities of the exciting mass and of the case of the pipe robot as functions of time are investigated. Results for steady state regime of motion are presented.
 Displacement of the first degree of freedom, velocity of the first degree of freedom, displacement of the second degree of freedom, velocity of the second degree of freedom as functions of time in the steady state regime of motion are investigated. Also, difference of displacements as well as difference of velocities as functions of time in the steady state regime of motion are represented.
 Results for three typical values of the constant force are described in the paper: first the results when the constant force is assumed equal to zero are presented and then the results for the two typical nonzero values of the constant force are presented. From the obtained graphical representations, the influence of the value of the constant force to the dynamic behavior of the pipe robot can be seen.
 The obtained graphical representations enable to understand the behavior of the investigated pipe robot with self-stopping mechanism.
 Keywords: pipe robot, self-stopping mechanism, harmonic excitation, steady state motions, parameters of the system.

On a new one‐dimensional k$$ \boldsymbol{k} $$–ε$$ \boldsymbol{\varepsilon} $$ turbulence closure for building‐induced drag

AbstractVarious urban canopy parameterizations (UCPs) have been developed in the last two decades to take into account the modifications induced by buildings on mean flow and turbulent fields in mesoscale meteorological models, the typical spatial resolution of which cannot resolve urban structures explicitly. In particular, several multilayer UCPs have been proposed, successfully reproducing wind‐flow characteristics in the urban environment. However, they often rely on length scales for the calculation of the eddy viscosity and the dissipation rate, which need to be tuned for various urban configurations. The main objective of this work is to address this shortcoming, by developing a new one‐dimensional turbulence closure that takes building‐induced turbulence into account independently of turbulence length scales. This model directly solves not only the equation for turbulent kinetic energy but also the equation for its dissipation rate (– model). Similar closure schemes have been successfully adopted for vegetated canopies, but their applicability to urban canopies is still unknown. The performance of the new – model, with additional sources and sinks for wind speed, turbulent kinetic energy, and dissipation rate, is tested by means of single‐column simulations in idealized urban areas, using different building packing densities. Results are in good agreement with spatially averaged building‐resolving CFD simulations. In particular, vertical profiles of mean and turbulent variables show better results with respect to simulations using turbulence closures adopting a parameterization of turbulence length scales. The best improvements are obtained for wind speed, reducing errors to half the typical values for standard UCP for high packing densities, and for the dissipation rate. Furthermore, besides the enhancement in the reproduction of the mean flow for urban areas, the proposed turbulence closure does not need additional tuning of coefficients depending on the packing density, resulting in a more general and efficient scheme.

INVESTIGATION OF TWO-SIDED SOFT IMPACTS

In various engineering devices used in robotics, transport and agricultural engineering two-sided impacts take place. In this paper two-sided soft impacts are investigated.
 Model of the investigated vibrating system with two-sided soft impacts is described in detail. Dynamics of the investigated system with two-sided soft impacts takes place according to the three typical regimes of motion: vibrating system is not connected with the supports, vibrating system is connected with the first support, vibrating system is connected with the second support.
 Results of numerical investigations are presented in the form of graphical relationships.
 Variation of displacement of the vibrating system, variation of velocity of the vibrating system, variation of displacement of the left support, variation of displacement of the right support, variation of the value of the force and variation of the quantity characterizing the regime of motion of the vibrating system as functions of time are investigated.
 Investigation of steady state regimes of motion for various stiffnesses of the supports is performed. Results for several typical values of stiffnesses of the supports are presented in the paper. The obtained graphical representations enable to understand the behavior of the investigated vibrating system with two-sided soft impacts in steady state regimes of motion for various stiffnesses of the supports.
 The obtained results of the performed investigation are applied in the process of design of pipe robots and other engineering devices.
 Keywords: two-sided impacts, soft impacts, harmonic excitation, nonlinear dynamics, left support, right support.

Elastic response of colloidal smectic liquid crystals: Insights from microscopic theory.

Elongated colloidal rods at sufficient packing conditions are known to form stable lamellar or smectic phases. Using a simplified volume-exclusion model, we propose a generic equationof state for hard-rod smectics that is robust against simulation results and is independent of the rod aspect ratio. We then extend our theory by exploring the elastic properties of a hard-rod smectic, including the layer compressibility (B) and bending modulus (K_{1}). By introducing weak backbone flexibility we are able to compare our predictions with experimental results on smectics of filamentous virus rods (fd) and find quantitative agreement between the smectic layer spacing, the out-of-plane fluctuation strength, as well as the smectic penetration length λ=sqrt[K_{1}/B]. We demonstrate that the layer bending modulus is dominated by director splay and depends sensitively on lamellar out-of-plane fluctuations that we account for on the single-rod level. We find that the ratio between the smectic penetration length and the lamellar spacing is about two orders of magnitude smaller than typical values reported for thermotropic smectics. We attribute this to the fact that colloidal smectics are considerably softer in terms of layer compression than their thermotropic counterparts while the cost of layer bending is of comparable magnitude.

Application and accuracy of shell theory in the analysis of stress and deformations in cylindrical pressure vessels

The presented study focusses on the application of the analytical shell theory to the problems of stresses and deformations in cylindrical pressure vessels. Two standard types of dished ends are investigated, torispherical and ellipsoidal. To solve the problem the membrane theory and edge effect theory is applied. The equations of deformations are formulated to calculate the forces in the shells junction. The orthotropic material model is taken into account. Two known solutions of the homogeneous Reissner– Meissner differential equations are studied. The resolved stress and deformation are compared with the numerical results of the finite element method. The accuracy of the analytical solution is highly dependent on the thickness of the pressure vessel, as well as on the shape of the dished end. According to the results discussed, the solution for the structure with torispherical dished ends is accurate only for exceptionally small thickness, beyond the typical values for industrial pressure vessels. This shortcoming has been proven to be the result of the limitations of the membrane theory, despite the thin-walled nature of the shells studied.

MOJAVE – XXI. Decade-long linear polarization variability in AGN jets at parsec scales

ABSTRACT Using stacking of images obtained at different epochs, we studied the variability properties of linear polarization of active galactic nucleus (AGN) jets on parsec-scales. Our sample is drawn from the MOJAVE programme, and consists of 436 AGNs manifesting core-jet morphology and having at least five VLBA observing epochs at 15 GHz from 1996 January through 2019 August, with some additional archival VLBA data reduced by us. We employed a stacking procedure and constructed maps of (i) standard deviation of fractional polarization and electric vector position angle (EVPA) over epochs as the measure of variability and (ii) median polarization degree to quantify typical values in time. The distributions of these values along and across the jet were analysed for the whole sample for the first time. We found that core EVPA variability is typically higher than that of the jet, presumably due to component blending and outflow bends in the core. The BL Lacertae object cores have lower EVPA variability, compared to that of quasars, possibly due to lower Faraday rotation measure, suggesting a stronger ordered magnetic field component. The EVPA becomes more stable down the jet. Most of the sources showing this trend have a time coverage of more than 12 yr and at least 15 epochs. The possible cause could be the increase of stability in the magnetic field direction, reflecting an increase in the fraction of the magnetic field that is ordered. There are no significant optical-class-dependent or spectral-class-dependent relations in the EVPA variability properties in AGN jets.

Validity and reliability of a new portable and cost-effective photoelectric cells device for measuring vertical jump performance: “The ADR Jumping”

The vertical jump is one of the most used testing movements to assess athlete’s physical performance and fatigue status in several sports. However, low-cost, portable, field-based, and reliable methods are needed to measure jumping performance. The aim of the current investigation was to assess the validity and reliability of a new photoelectric cells device (ADR) for measuring the vertical jump height. Twenty-three trained male participants (age: 24.8 ± 5.2 years, body mass: 74.2 ± 7.3 kg; height: 1.76 ± 0.04 m) performed four maximal countermovement jumps (CMJ). Flight time-derived jump height was extracted simultaneously from three devices including a force plate (FP) (Kistler Quattro-Jump, criterion measurement) and two photoelectric cells (PC) devices (ADR and Optojump). The ADR mean CMJ height measurements demonstrated substantial validity compared to both FP and Optojump ( r = 0.98 p < 0.01). Intraclass correlation coefficients (ICCs) for reliability were classified as good to excellent for the three devices (0.986–0.994). All devices showed similar coefficients of variation (CV%), classified as very good (3.21–3.85), whereas observed standardized typical error values (STE) were small (1.29–1.39). The ADR Jumping device can be considered an affordable, reliable, and valid method to measure vertical jump height thereby making it a practical resource for coaches when monitoring the training process.

Thermal performance augmentation of parabolic trough solar collector using nanomaterials, fins and thermal storage material

Investigating and evaluating parabolic trough collector's (PTC) thermal performance have been shed out numerically by many researchers. Only a few researchers have focused their attention on using experiments to study the PTC's thermal performance. Consequently, the objective of this paper is to utilize an experimental method to put more shed on the PTC performance using active and passive methods. This aim is achieved by developing an experimental setup with modifications in reference parabolic trough collector (RPTC) and employing different heat transfer fluids. RPTC modifications include adding fins to the outer tube surface (FPTC), coating the absorber with Copper Oxide nanoparticles (CuO) combined with black paint (NCPTC), and filling the annulus with graphite (GPTC). Heat Transfer fluid (HTF) is changed by inserting CuO nanoparticles into water (NFPTC). All experiments are performed during August 2021 in Kafrelsheikh University. Data such as: inlet and exit temperatures of HTF, air temperature, air speed, solar irradiation, and rate of mass flow of HTF are recorded hourly for RPTC, NFPTC, NCPTC, NF-NCPTC, FPTC, and GPTC. Based on these data, thermal efficiency is calculated. FHT mass flow rate is controlled and typical values of 8, 10, 14, 16, 20, and 26 l/h are employed with RPTC in purpose to explore the optimum value based on practical considerations, HTF temperature difference, and higher efficiency. This value is found to be 20 l/h and is used in all modified collectors. All modified collectors' thermal performance is studied and compared with the traditional collector. The main finding in present study indicates that there is an augmentation in the thermal efficiency by 19.18 %, 26.23 %, 37.76 %, 44.43 %, and 54.82 % for NFPTC, NCPTC, NF-NCPTC, FPTC, and GPTC respectively when compared with RPTC.

Research on fusion splicing technology of 7-core fiber

The actual trunk multi-core fiber (MCF) splicing is studied by a 7-core fiber for long-distance transmission. The results show that the quality of MCF splicing affects both transmission loss and crosstalk. The splicing quality is influenced by end-face treatment, discharge intensity, discharge time, electrode spacing and other parameters. By aligning the fibers controlled by the axis algorithm and optimization of the fusion splicing parameter, the typical value of splicing point loss can be less than 0.3 dB, which can better meet the requirements of application for engineering wiring.

High-resolution silicon photonics focused ultrasound transducer with a sub-millimeter aperture.

We present an all-optical focused ultrasound transducer with a sub-millimeter aperture and demonstrate its capability for high-resolution imaging of tissue ex vivo. The transducer is composed of a wideband silicon photonics ultrasound detector and a miniature acoustic lens coated with a thin optically absorbing metallic layer used to produce laser-generated ultrasound. The demonstrated device achieves axial resolution and lateral resolutions of 12 μm and 60 μm, respectively, well below typical values achieved by conventional piezoelectric intravascular ultrasound. The size and resolution of the developed transducer may enable its use for intravascular imaging of thin fibrous cap atheroma.

Effect of voltage elevation on cost and energy efficiency of power electronics in water electrolyzers

The interest in green hydrogen has been increasing in recent years for several applications, such as energy storage and different industrial sectors. The green hydrogen is produced from water electrolysis supplied by renewable electricity. The operation of industrial large-scale water electrolysis is characterized by a high DC current in the kiloampere range and a few hundred volts. Therefore, the rectifier unit plays an important role in converting AC current of the electricity grid into DC current supplied to the electrolyzer. The power electronic converters are also considered as one of the main cost components of the water electrolyzer system. The objective of this paper is to study whether the operation at a higher voltage than typical values (200 V–300 V) can be beneficial both for the cost and energy efficiency of the power converters in water electrolyzer systems. In this study, three different rectifier topologies considered for an industrial-scale electrolyzer are analyzed and compared in terms of energy efficiency and cost. The simulation models of each topology are carried out in the Matlab/Simulink environment.

Dosage Optimization of Digoxin in Older Patients with Heart Failure and Chronic Kidney Disease: A Population Pharmacokinetic Analysis.

Renal function is an important index for digoxin dose adjustment, especially in patients with chronic kidney disease (CKD). Decreased glomerular filtration rate is common in older patients with cardiovascular disease. The aim of this study was to establish a digoxin population pharmacokinetic model in older patients with heart failure and CKD and to optimize the digoxin dose strategy. Older patients with heart failure and CKD aged > 60years from January 2020 to January 2021 and who had an estimated glomerular filtration rate (eGFR) < 90mL/min/1.73m2 or urine protein production were enrolled in this retrospective study. Population pharmacokinetic analysis and Monte Carlo simulations (n = 1000) were performed using NONMEN software. The precision and stability of the final model were analyzed by graphical and statistical methods. Overall, 269 older patients with heart failure were enrolled. A total of 306 digoxin concentrations were collected, with a median value of 0.98ng/mL (interquartile range [IQR] 0.62-1.61, range 0.04-4.24). The median age was 68years (IQR 64-71, range 60-94) and eGFR was 53.6mL/min/1.73m2 (IQR 38.1-65.2, range 11.4-89.8). A one-compartment model with first-order elimination was developed to describe the digoxin pharmacokinetics. Typical values for clearance and volume of distribution were 2.67L/h and 36.9L, respectively. Dosage simulations were stratified by eGFR and metoprolol. Doses of 62.5 and 125μg were recommended for older patients with eGFR < 60mL/min/1.73m2. A population pharmacokinetic model of digoxin in older patients with heart failure and CKD was established in this study. A novel digoxin dosage strategy was recommended in this vulnerable population.

Waking the monster: The onset of AGN feedback in galaxy clusters hosting young central radio galaxies

Aims. The investigation of the feedback cycle in galaxy clusters has historically been performed for systems where feedback is ongoing (“mature-feedback” clusters), that is where the central radio galaxy has inflated radio lobes, pushing aside the intracluster medium (ICM). In this pilot study, we present results from “pre-feedback” clusters, where the central newly active radio galaxies (age &lt; 103 yr) may not yet have had time to alter the thermodynamic state of the ICM. Methods. We analyze Chandra and MUSE observations of two such systems, evaluating the hot gas entropy and cooling time profiles, and characterizing the morphology and kinematics of the warm gas. Results. Based on our exploratory study of these two sources, we find that the hot gas meets the expectations for an as of yet unheated ICM. Specifically, the entropy and cooling time of pre-feedback clusters within 20 kpc from the center fall below those of mature-feedback clusters by a factor ∼2. We speculate that with an estimated mechanical power of ∼1044 − 1045 erg s−1, the two young radio galaxies may restore the entropy levels in a few tens of millions of years, which are typical values of power outbursts and lifetimes for radio galaxies in clusters. Conversely, the properties of the gas at ∼104 K seem to remain invariant between the two feedback stages, possibly suggesting that the warm gas reservoir accumulates over long periods (107 − 108 yr) during the growth of the radio galaxy. We conclude that the exploratory results obtained from our analysis of two cluster-central young radio galaxies are crucial in the context of understanding the onset of active galactic nuclei feedback, and they provide enough motivation for further investigation of similar cases.

Pharmacokinetics of buprenorphine and its metabolite norbuprenorphine in neutered male cats anesthetized with isoflurane

ObjectiveTo characterize the pharmacokinetics of buprenorphine and norbuprenorphine in isoflurane-anesthetized cats. Study designProspective experimental study. AnimalsA group of six healthy adult male neutered cats. MethodsCats were anesthetized with isoflurane in oxygen. Catheters were placed in a jugular vein for blood sampling and in a medial saphenous vein for buprenorphine and lactated Ringer’s solution administration. Buprenorphine hydrochloride (40 μg kg–1 over 5 minutes) was administered intravenously. Blood samples were collected before buprenorphine administration and at various times up to 12 hours after administration. Plasma buprenorphine and norbuprenorphine concentrations were measured using liquid chromatography/tandem mass spectrometry. Compartment models were fitted to the time-concentration data using nonlinear mixed effect (population) modeling. ResultsA five-compartment model (three compartments for buprenorphine and two compartments for norbuprenorphine) best fitted the data. Typical value (% interindividual variability) for the three buprenorphine volumes of distribution, and the metabolic clearance to norbuprenorphine, the remaining metabolic clearance and the two distribution clearances were 157 (33), 759 (34) and 1432 (43) mL kg–1, and 5.3 (33), 16.4 (11), 58.7 (27) and 6.0 (not estimated) mL minute–1 kg–1, respectively. Typical values (% interindividual variability) for the two norbuprenorphine volumes of distribution, and the norbuprenorphine metabolic and distribution clearances were 1437 (30) and 8428 (not estimated) mL kg–1 and 48.4 (68) and 235.9 (not estimated) mL minute–1 kg–1, respectively. Conclusions and clinical relevanceThe pharmacokinetics of buprenorphine in isoflurane-anesthetized cats were characterized by a medium clearance.

Balanced Mix Design Production Analysis of Asphalt Mixtures in Vermont

Performance testing has been recognized by state highway agencies and the asphalt paving industry as an important tool to complement volumetric properties for improving asphalt pavement performance. Thus, the Vermont Agency of Transportation (VTrans) began evaluating the Hamburg wheel-tracking test in 2015, Illinois flexibility index test in 2018, and indirect tensile cracking test in 2020 as steps toward balanced mix design (BMD) implementation. These tests were conducted on reheated common plant-produced asphalt mixtures for multiple shadow projects, and the results were analyzed to determine the typical production variability observed in the performance testing results. Production variability is important to assess potential specifications in field production, especially for statistical quality acceptance procedures, such as percent within limits. Based on the percent within limit analysis, most of the modified Type IVS (i.e., 9.5 mm) mixtures would be acceptable based on the proposed performance requirements, while those found not acceptable were close to meeting the performance requirements and would need minimal adjustments. The lot data was further examined to generate typical lot production variability values for potential use in specification development. The information from this research effort will help VTrans achieve its goal to move beyond solely volumetric properties for asphalt mixture design and acceptance and serve as an example for other agencies exploring the implementation of BMD for improving asphalt pavement performance.

Factors Influencing the Spatial Distribution of Regulating Agro-Ecosystem Services in Agriculture Soils: A Case Study of Slovakia

Agro-ecosystem services assessment and mapping are one of the main requirements for implementing the concept of ecosystem services into institutional decision-making within the European Union and worldwide. The aim of this study was to identify the most important regional drivers of the natural potential of regulating ecosystem services with agricultural soil in Slovakia, resulting in an original set of macro-scale spatial stratification criteria for agricultural land, and to estimate typical middle values of its potential in newly defined regions. The non-monetary assessment was based on natural environment parameters and land use factors. For the assessment of individual indicators of agro-ecosystem services, we utilized an expert scoring system. We evaluated ecosystem services on the basis of biophysical indicators that determine the corresponding soil functions and are part of the existing databases available in the Slovak Republic. The new methodological combination enabled us to provide unique mapping and assessment of agro-ecosystem services within Slovakia. Regional climate, land cover, and soil slope were identified as key factors impacting agro-ecosystem services potential within the country, which can be used as data stratification levels for further analyses. Linking the value of individual regulating agro-ecosystem services potential with geographical distribution can help to optimize its potential depending on the needs of the inhabitants living in different regions by introducing appropriate measures and can contribute to effective agricultural policymaking.

USE OF SIMILARITY METRICS IN ROBUST TIME DELAY ESTIMATION

This paper addresses the task of time delay and direction of arrival estimation for a source of the wideband signal using two sensors with fixed displacement. The peculiarity of the task statement is that a limited time of signal observation is supposed and additive noise is assumed non-Gaussian with a heavy-tail distribution. This leads to a high probability of abnormal estimates for the conventional signal processing method based on cross-correlation. To decrease this probability, it is proposed to reformulate the task of cross-correlation processing to the task of similarity estimation between two data arrays. This allows using different similarity metrics, particularly those that have less sensitivity to outliers in data (impulse noise), and, thus, provide better robustness for non-Gaussian environments typical for several applications of time delay estimation. More than ten different similarity metrics are considered for the model of the symmetric α-stable distribution describing noise properties. It is shown that some metrics including cosine distance, Hellinger, and some others are able to provide sufficiently better accuracy of time delay estimation both in the sense of less RMSE of normal estimates and probability of abnormal estimates for typical values of α and a wide range of γ values for symmetric α-stable distribution.

Analysis of Specific Greenhouse Gas Emissions Savings from Biogas Production Based on Agricultural Residues and Industrial By-Products

The aim of this study was to analyse specific greenhouse gas emissions savings for a variety of agricultural residues, industrial by-products, and municipal biowaste. One of the most viable alternatives to fossil fuels is bioenergy, particularly biogas produced by the anaerobic digestion of renewable feedstocks. The revised Renewable Energy Directive (D 2018/2001) recognizes that biogas production from agricultural residues, livestock production, and industrial by-products is an acknowledged greenhouse gas mitigation technology in cases where their use results in a certain level of specific greenhouse gas savings. This study delivered values for the maximum transport distance of agricultural residues and industrial by-products to achieve the greenhouse gas (GHG) emissions-saving requirement defined by Directive 2018/2001. It analysed the greenhouse gas emissions reduction for numerous feedstocks for which Directive 2018/2001 has not defined the default and typical values but which could be used as sustainable substitutes for currently dominantly used maize silage in biogas production. The results obtained in this work define the maximum transport and distribution distance for which biogas produced from considered feedstocks achieved required specific greenhouse gas emissions savings (80%), compared with fossil fuel comparator. The obtained results can be used as the constraints in the optimisation of the biomass supply chains for the feedstocks considered in this work.

We like to move it, move it: A perspective on performing passive leg movement as a non-invasive assessment of vascular function in pediatric populations.

The passive leg movement (PLM) technique is a non-invasive assessment of lower-limb vascular function. PLM is methodologically simple to perform and utilizes Doppler ultrasound to determine leg blood flow (LBF) through the common femoral artery at rest and in response to passive movement of the lower leg. LBF responses to PLM have been reported to be mostly nitric oxide (NO)-mediated when performed in young adults. Moreover, PLM-induced LBF responses, as well as the NO contribution to PLM-induced LBF responses, are reduced with age and in various diseased populations, demonstrating the clinical utility of this non-invasive test. However, no PLM studies to date have included children or adolescents. Since its conception in 2015, our laboratory has performed PLM on hundreds of individuals including a large cohort of children and adolescents. Thus, the purpose of this perspective article is threefold: 1) to uniquely discuss the feasibility of performing PLM in children and adolescents, 2) to report PLM-induced LBF values from our laboratory in 7-17-year-olds, and 3) to discuss considerations for making comparisons among pediatric populations. Based on our experiences performing PLM in children and adolescents (among various other age groups), it is our perspective that PLM can feasibly be performed in this population. Further, data from our laboratory may be used to provide context for typical PLM-induced LBF values that could be observed in children and adolescents, as well as across the lifespan.

Building integrated innovative non-imaging concentrating solar collector for clean cooking under low sun elevation

This paper aims to report the building-integrated innovative non-imaging solar thermal collector (BISTC) for cooking, which is constructed and tested under field conditions in two configurations. A ray tracing analysis enables an understanding of the optics of the BISTC.The results show that BISTC attained a temperature in the range of 110–124 °C under low sun elevation and ensures the potential for better cooking performance under high sun elevation. The mean values of the Cooker Opto-thermal Ratio (COR) for BISTC1 and BISTC2 are 0.109 and 0.116 ((m2-°C)/W), respectively. Typical theoretical and experimental values of maximum achievable load temperature (Tfmax) are 129.8 °C and 119 °C and that for reference time (τR) are 77 and 76 min, respectively, for BISTC1. The typical theoretical and experimental values of Tfmax are 137.5 °C and 124.7 °C and that for τR are 80.7 and 75 min, respectively, for BISTC2.This work provides vital information about the opto-thermal behavior of the non-tracking type solar cooker design, i.e., BISTC, which can lead to the creation of similar systems for regular or building-integrated solar cooking. Thus, the BISTC is one of the promising technologies to be promoted with several future-optimized designs to fulfill sustainable development goals.