Real Size Research Articles

The market of air transportation and cargo transportation in the investment strategy of transport enterprises

The article discusses the investment strategy of transport enterprises, which defines the concept of the development of the investment activity of the enterprise. The effectiveness of the development of the investment strategy of transport enterprises depends on the dynamism of the factors of the external investment environment, both direct and indirect. The relationship of the investment strategy with the elements of the overall strategy of the development of the transport enterprise, such as: marketing strategy, market strategy of the enterprise, financial strategy, advertising strategy, allows you to make the process of its development more effective. In the context of a pandemic, the activity of the air and cargo transportation market plays an important role in the investment strategy of transport enterprises. The analysis of the capacity of the air transportation market is presented, characterizing the capacity of the market for three years, as well as forecast data broken down by service classes (first class, business class and economy class), as well as the definition of capacity in its potential and real size.

Determination of Cracks using Multiple DC Potential Drop Measurements – Experimental Verification of an Advanced Model

The Direct Current Potential Drop Method (DCPDM) is a frequently used technique for crack detection and crack length measurement in fatigue experiments. Recent investigations have shown that with multiple potential drop measurements the location of crack initiation can be determined in single edge notch specimens (Wiehler and Bär, 2020), (Bär and Nahbein, 2022) and in round bars (Hartweg and Bär, 2019). In the present work a more detailed investigation of crack initiation and propagation is undertaken on round bars to advance the geometrical model by Hartweg and Bär (2019). Three potential probes were equipped on notched steel bars – at 0° (U1), at 120° (U2) and at 240° (U3). The three potentials were measured simultaneously during the fatigue tests using amplifiers of the control electronics. Moreover, the introduction of overloads was used to mark the crack front on the fracture surface in defined intervals to compare crack and size calculated from the potential drop measurements with the real crack size and geometry.In the case of an initiated single crack, the experimental set-up delivers different potentials depending on the distance of the probes to the crack. The geometrical model can be used not only for the determination of the crack angle like performed by Hartweg and Bär (2019) but also to calculate the crack size. On the measured data a function is fitted that allows the calculation of the crack length independent of the location of the crack initiation site. The experimental results have shown that it is possible to determine a crack with a size of less than 1 % of the specimen cross-sectional area.

Разработка и тестирование модели поглощения энергии в биообъектах от инкорпорированных излучателей фотонов

A new analytical method, previously developed for estimating beta absorbed fractions, was ex-tended for analytical estimating photon absorbed fractions in soft-tissue bodies from internal uni-formly distributed gamma emitters. The method involves a rescaling procedure with transfor-mation of real biological sizes to unitless effective ones combining information of both photon energy and object’s size. The rescaling was applied to large published datasets of photon ab-sorbed fractions in soft-tissue spheres. A new effect was demonstrated: the rescaled data were united into a single smooth “universal curve” with saturation. The universal curve for photon ab-sorbed fractions was described analytically as a function of a single argument – a rescaled effec-tive radius. Practical applicability of the approach for non-spherical convex bodies (ellipsoids) was demonstrated. Examples of analytical estimating the internal dose coefficients for repre-sentative terrestrial animals were calculated. The new method now available for electron and photon internal dosimetry, provides an effective analytical tool for calculating radiation absorbed fractions in organs and bodies of soft-tissue organisms.

Contribution of the introduction of artificial defects by additive manufacturing to the determination of the Kitagawa diagram of Al-Si alloys

Despite the continuous progress in the additive manufacturing (AM) technologies to improve the quality of the produced parts, the presence of defects induced by the process remains a critical issue for the design of industrial components with respect to fatigue damage. Analytical models such as Kitagawa diagrams represent easy to use tools to predict fatigue strength accounting for the detrimental influence of the defects. They are therefore of great interest from an industrial point of view. The aim of the present work is to evaluate whether artificial defects obtained by placing holes directly into the CAD files of fatigue specimens can be used to establish Kitagawa diagrams, despite some differences in terms of shapes and morphologies between the natural and artificial defects. Two artificial defect geometries with a similar size were studied. For each of these geometries, the experimental fatigue strengths and the real sizes of the critical defects measured from the fracture surfaces were used to determine the parameters of the El-Haddad model. For one of the geometries, the obtained model was able to predict the fatigue strength corresponding to the natural defects, and the associated parameters were found consistent with the literature. The fatigue tests results also highlighted the influence of the defect shape.

Release of overpressures in computational simulations of air-methane explosions

Research in the field of gas explosions has had and continues to have, as its main support, physical experiments performed on various scale models, the construction of real size models are often large consuming materials, time and labor. The rapid development of computing techniques has allowed among other things, the transfer of gas explosions research in the virtual space, for the validation of computational simulations of this type being still considered physical experiments and specialty literature. Within NIRD INSEMEX Petrosani, being an accredited institute in the elaboration of technical reports for gas explosion type events, the phenomenon of rapid combustion virtualization increased in time and as a result, computational simulations becoming an efficient tools in explaining the mechanisms of explosion production. Nevertheless, one of the problems raised by this virtualization process is the limitation of performing computational simulations in closed or partially closed spaces, initial conditions imposed, without the possibility of dynamic modification of these conditions according to the development of overpressures generated by the virtual explosion. This paper presents a computational experiment in which it was possible to transform the boundary conditions at predefined pressure thresholds, from rigid surfaces into surfaces capable of releasing the overpressures developed in closed / partially closed spaces, putting the results of this kind of simulations in line with real dynamic effects of gas explosion events.

A Flexible Mechanism Based Vibration Isolator for Machine Tool Application

The paper presents novel design of vibration absorber with innovative features including use of flexible link based mechanism at the interface of tool holder and cutting tool. The mechanism ensures modification of the dynamic force interaction at the damping element and results in lower force transmissibility. It ensures amplification of the relative velocity at the damping element, which results in significant reduction of the damping element mass used for energy dissipation. The presented absorber has advantages of passive and economical operation in comparison to the active and semi-active solutions. Further, the proposed solution results in up to 53% reduction in the force transmissibility. A real size design has been presented for frequency range of 0-1100 Hz and maximum force amplitude of 700 N. Numerical simulations have been performed with consideration of flexible joint and structural element dynamics. Simulation results with FEA and PRBM approach have been compared with detailed analysis of the important design parameters.

Vietnam public debt forecast in the period of 2021 - 2025

Vietnam's public debt has an important achievement in the years 2017-2019. Specifically, the public debt/GDP ratio was 61.4% of GDP in 2017. However, this ratio fell to 58.3% in 2018 and 55% in 2019. This improvement in public debt/GDP is due to the large scale of the economy and high economic growth rate. This fact implies there is a relationship between public debt and macroeconomic factors. Theoretical research shows that the macroeconomic factors affecting public debt include the State budget deficit, economic growth, real interest rates and exchange rates. This study will build a model to analyze the impact of those macroeconomic factors on public debt/GDP, period 2000 - 2020. The study has an important finding. That is, there exist two mechanisms, which have opposite effects on the evolution of public debt/GDP of Vietnam. Firstly, it is the trend of expanding investment to promote growth. This trend increases public debt/GDP. And second, it is the tendency to increase the real size of the economy, as measured by real GDP growth. This trend reduces public debt/GDP. The author relies on the above two trends to explain the evolution of Vietnam's public debt/GDP, period 2000 - 2020. Next, based on the analytical model, the author will forecast the trend of public debt in the period 2021 -2025. The forecast takes into account the impact of Covid-19 on public debt.

ПРЕКАРИАТ КАК ФАКТОР ТРУДОВОЙ МИГРАЦИИ НАСЕЛЕНИЯ

The article reveals the key problems of a new social class formation, the definition of socio-economic consequences for society and the labor market, the definition of dependencies and the impact of the precarization process on migration flows in the context of a change in technological structure. At the present time, when precariums are widely represented in all spheres of the economy, and the steady predominance of specific forms of able-bodied population employment and the formation of non-standard socio-economic relations increasingly determine the nature of the modern post-industrial society development, there is an urgent need to develop a methodology for identifying representatives of the precariat to assess the real size of a new developing class and modeling the effects of the labor market precarization. Today, one can observe the degradation of the classical institution of labor relations, the main features of which have always been permanent employment, career prospects, social guarantees and employee security. The established institution of labor relations was replaced by unstable forms of employment with the lack of a protected socio-economic status of workers — precarization. The scientific problem to which the article is devoted is the fundamental justification of the process of precarization of the labor market, the definition of its scope, consequences, qualitative characteristics and management approaches.

Air Moving Target Imaging for Staggered ISAR

The rapid development of the modern electronic counter-countermeasures (ECCMs) has made the conventional inverse synthetic aperture radar (ISAR) associated with the regular signal waveforms more vulnerable and unreliable. To deal with this issue, the complex waveform designment with staggered pulse sampling is developed in an ISAR system in this letter. In the proposed method, the generalized time-scaled transform (GTST) is adopted to effectively accomplish the irregular signal reconstruction and linear phase decoupling. After that, a set of matched filtering functions are established and interspersed in the imaging processes to accomplish the subsequent motion compensation, target imaging, and range and cross-range scaling. Finally, a satisfied ISAR imagery corresponding to the real size of a moving target can be recovered. The simulation and real-measured radar data processing results are applied to demonstrate the effectiveness of the proposed method.

Flow visualisation in real-size optical injectors of conventional, additised, and renewable gasoline blends

Research on renewable and alternative fuels is crucial for improving the energy and environmental efficiency of modern gasoline internal combustion engines. To highlight the influence of fuel rheological and thermodynamic properties on phase change and atomisation processes, three types of gasoline blends were tested. More specifically, the campaign comprised a reference gasoline, an ethanol/gasoline blend (10% v/v) representative of renewable fuels, and an additised gasoline sample treated with viscoelasticity-inducing agents. High-speed imaging of the transient two-phase flow field arising in the internal geometry and the near-nozzle spray region of gasoline injectors was performed employing Diffuse Backlight Illumination. The metallic body of a commercial injector was modified to fit transparent tips realising two nozzle layouts, namely a two-hole real size model resembling the Engine Combustion Network spray G injector and an enraged replica with an offset hole. Experiments were conducted at realistic operating conditions comprising an injection pressure of 100 bar and ambient pressures in the range of 0.1–6.0 bar to cover the entire range of chamber pressures prevailing in Gasoline Direct Injection engines. The action of viscoelastic additives was verified to have a suppressive effect on in-nozzle cavitation (6% reduction in cavitation extent) , while also enhancing spray atomisation at flash-boing conditions, in a manner resembling the more volatile gasoline/ethanol blends. Finally, persisting liquid ligaments were found to form after the end of injection for the additised sample, owing to the surfactant nature of the additives.

Development of a method for improving the accuracy of measurement of linear measures of 3D models via scanning

The object of research is to refine the linear sizes of the obtained 3D models via scanning, and reducing the numbers of errors when obtaining the model. For now, there is no accuracy method for transferring the actual sizes of an object to a 3D model. One of the most problematic places in the existing methods of transferring sizes from the object to the model is the error in the placement of dimensional markers due to inaccuracy, or poor quality of the received surface via scanning. A model of the instrument complex is used to implement an improved method of 3D scanning, based on the photogrammetric method. The advanced technology of construction and measurement of 3D models on the basis of photos on the principle of stereo pairs in combination with image projection is based on a combination of existing scanning methods. As well as the introduction of new functionalities, such as maintaining the actual sizes of an object, its textures, color and light characteristics, as well as improving the accuracy of linear sizes. As a result of the use of a standard, reference projections, and a new method of comparing photographs to build a 3D model, a 60 % increase in the accuracy of linear dimensions was achieved. This is due to the fact that the proposed new combined method incorporates all the existing most important aspects of scanning. And also has a number of features, such as the definition of boundary surfaces, automatic sizing, detection, and processing of glass and mirror surfaces. Due to this, this method eliminates the main disadvantages of the usual photogrammetric method – inaccuracies in the surface quality of the models, and inaccuracies in the transfer of linear dimensions. It is estimated that the combined method will allow to transfer the real size of simple objects in 3D with an accuracy of 99.97 % of the actual size of the object. It will also improve the quality of complex surfaces (boundary, glass, mirror) by at least 40–60 %, compared to other existing methods.

Assessing the spillover effects of investment in transport infrastructure in the subjects of the Russian Federation

Subject. We consider economic relations and problems within the framework of spatial development of settlements and constituent entities of the Russian Federation. Objectives. We focus on the development of a methodology for assessing the spacial spillover effects of investments in transport infrastructure and their monetization, considering the network and spillover effects, socio-economic characteristics, geographical location, and the level of connectivity of territories. Methods. The study employs methods of economic, statistical analysis and synthesis, and comparison. The works of economists on the problems of transport accessibility, spatial development and the impact of transport infrastructure on the dynamics of economic growth serve as the theoretical basis of the study. Results. We tested the proposed methodological toolkit, presented the results of assessing the spillover effects of investments in transport infrastructure based on the materials of the Central Federal District according to data for 2020. We determined the secondary effects of infrastructure investments, assessed the size of ‘exports’, ‘imports’ and the real size of investments in transport infrastructure, considering the secondary effects for the subjects of the Central Federal District. Conclusions. The numerical estimates of the spillover effects of investments in transport infrastructure for the subjects of the Central Federal District obtained in the work can be used in practice, when planning the development of territories and assessing the socio-economic effects of regional and interregional transport projects.

An electromagnetic arrayed pump to create arbitrary velocity profiles in fluid

The present paper is conducted to develop a new structure of an electromagnetic pump capable of controlling the magnetic field in a rectangular channel. Common electromagnetic pumps do not create uniform velocity profiles in the cross-section of the channel. In these pumps, an M-shape profile is created since the fluid velocity in the vicinity of the walls is higher than that in its center. Herein, the arbitrary velocity profiles in the electromagnetic pump are generated by introducing an arrayed structure of the coils in the electromagnetic pump and implementing 3D numerical simulation in the finite element software COMSOL. The dimensions of the rectangular channel are 5.5 × 150 mm2. Moreover, the magnetic field is provided using a core with an arrayed structure made of low-carbon iron, as well as five couples of coils. 20% NaoH solution is utilized as the fluid (conductivity: 40 S/m). The arrayed pump is fabricated and experimentally created an arbitrary velocity profile. The pressure of the pump in every single array is 12 Pa and the flow rate is equal to 3375 mm3/s. According to the results, there is a good agreement between the experimental test carried out herein and the simulated models.Article highlightsThis is the first time that the idea of arrayed electromagnetic pump is presented. This pump uses a special arrayed core with coils; by controlling the current of each coil and the direction of the currents, the magnetic field under the core could be adjusted. By changing the magnetic field at any position in the width of the channel, the Lorentz force alters, which leads to different velocity and pressure profiles.Using COMSOL multiphysics software, the electromagnetic pump was simulated in real size compared to the experimental model. Subsequently, the simulation model was verified and different velocity profiles were generated by activation and deactivation of different coils. The pressure and velocity curves and contours were extracted.The experimental setup was manufactured and assembled. NaOH solution was utilized as the fluid. Afterwards, different modes of coil activations were investigated and the pressure and velocity profiles of the pump were calculated.

Limitations of cardiothoracic ratio derived from chest radiographs to predict real heart size: comparison with magnetic resonance imaging

BackgroundCardiothoracic ratio (CTR) in chest radiographs is still widely used to estimate cardiac size despite the advent of newer imaging techniques. We hypothesise that a universal CTR cut-off value of 50% is a poor indicator of cardiac enlargement. Our aim was to compare CTR with volumetric and functional parameters derived from cardiac magnetic resonance imaging (MRI).Methods309 patients with a chest radiograph and cardiac MRI acquired within a month were reviewed to assess how CTR correlates with multiple cardiac MRI variables: bi-ventricular EDV (absolute and indexed to body surface area), EF, indexed total heart volume and bi-atrial areas. In addition, we have also determined CTR accuracy by creating multiple ROC curves with the described variables.ResultsAll cardiac MRI variables correlate weakly but statistically significantly with CTR. This weak correlation is explained by a substantial overlap of cardiac MRI parameters in patients with normal and increased CTR. For all variables, CTR was only mildly to moderately better than a chance to discriminate cardiac enlargement (AUC 0.6–0.7). Large CTR values (> 55%) are specific but not sensitive, while low CTR values (< 45%) are sensitive but not specific. Values in between are not sensitive nor specific.ConclusionsCTR correlates weakly with true chamber size assessed by gold standard cardiac MRI and has a weak discriminatory power. Thus, clinical decisions based on intermediate CTRs (45–55%) should be avoided. Large CTRs (> 55%) are likely indicative of true heart chamber enlargement. Low CTRs (< 45%) are likely indicative of normal heart size.

Design of Massive Image Duplicate Search Algorithm in Cloud Computing Environment

Massive image replay algorithm adopts cloud computing technology to realize image uploading, processing and classification on cloud platform. Image classification is realized by image classifier. Zernike matrix was used to compare the classified images and determine the pseudo-edge blocks around the image. According to the pixel value of the image, the binarization method was used to process the image. After processing, edge detection and line detection were carried out to determine the real image size. The similarity of two real images is calculated by normalized similarity criterion, and the image repetition is judged accordingly. The results show that the accuracy of the algorithm is higher than 99%, and the accuracy of the algorithm is higher than that of the comparison algorithm, and the accuracy of the algorithm is the highest when the similarity threshold is 0.8∽0.9.

A Novel All-Superconducting Propulsion and Protection System for the HTS Maglev: Concept, Experimental Verification and Planning

This article presents a novel all-superconducting propulsion and protection system for the high-temperature superconducting (HTS) Maglev. The HTS magnet is the key component in the HTS Maglev, as it is in charge of the most crucial works, the propulsion and levitation of the train, to realize the zero-friction and ultra-high-speed just above the ground. The HTS magnet can conduct massive electric current and generate extremely high magnetic field, but the HTS magnet is also relatively venerable compared to the conventional copper magnet, regarding the strict operating conditions of temperature, magnetic field and electric current. Therefore, we proposed a new all-superconducting propulsion and protection system, introducing the superconducting fault current limiter (SFCL) and superconducting magnetic energy storage (SMES) to be equipped into the HTS Maglev, which can protect the HTS magnet, but also ensure the safety and reliability of Maglev operation. The real size HTS magnet was modeled to check the magnetic requirements of HTS Maglev and determine the specifications of other superconducting devices. Then a scaled all-superconducting protection and energy compensation system with the scaled HTS magnet, SFCL and SMES was analyzed, and some components were verified by experiments. Future plans were proposed to merge the full size all-superconducting protection and protection system into an HTS Maglev prototype.

Glomerular Size in Transplanted Kidneys: Does Size Matter?

Glomerular Size in Transplanted Kidneys: Does Size Matter?

Investigation and Quantification of Irreversible Degradations and Their Sensitivities during the Start-up Phases of PEMFC By an Accelerated Emulation Approach

In automotive application, frequent Start-up/Shut-down (SU/SD) phases of PEMFC system are prone to cause severe degrading conditions. Many studies have been achieved over the past decades to better understand and to mitigate MEA aging and performance decay due to the well-identified reverse current mechanism1. Indeed, the H2|Air front during H2 injection at the air-filled anode creates two sub-cells: H2/Air sub-cell operating in Fuel Cell mode and Air/Air sub-cell operating in Electrolysis Cell mode. This second sub-cell is subjected to high potential at cathodic side (about 1.6 V vs RHE), leading to harsh corrosion of both Pt nanoparticles and carbon support within the cathode catalyst layer. Two main mitigating solutions are generally proposed in the literature: (i) development of more stable materials and (ii) improvement of system control 2,3. Experimental DOE AST4 is usually performed only on small single cell to evaluate MEA component durability. Nevertheless, these tests cannot be fully correlated with real automotive operating conditions to predict PEMFC stack lifetime.In this work, more realistic AST protocols in regard to PEMFC stack/system configuration during start-up phase are proposed. Our experimental approach consists in emulating a representative transient cathodic potential profile (Figure a and b) during the H2|Air front formation and propagation along anodic channel using a 100 cm² single cell with a real stack active area design5. A comprehensive investigation and quantification of degradations caused by reverse current was carried out under SU cycling. Additional sensitivity study on the main operating parameters (potential profile, relative humidity and temperature) was performed to evaluate their respective impact on the cathode degradation and the performance losses. Periodic measurements such as polarization curves and cyclic voltammetry (Figure c) are coupled with CO/CO2 gas emission analysis (Figure d) during cycling at cathode to monitor and quantify the physical and electrochemical modifications within the MEA during our aging SU cycles.On the whole, this original experimental study proposes an overall degradation mechanism and these results are compared with model prediction to validate the most impactful parameters during reverse current phases at the real cell size and design. Ultimately, it will provide key-data to propose and optimize finely different mitigation strategies to be used in PEMFC stack and systems. References Reiser, C. A. et al. A reverse-current decay mechanism for fuel cells. Electrochemical and Solid-State Letters 8, A273–A276 (2005).Zhang, T., Wang, P., Chen, H. & Pei, P. A review of automotive proton exchange membrane fuel cell degradation under start-stop operating condition. Applied Energy 223, 249–262 (2018).Yu, Y. et al. A review on performance degradation of proton exchange membrane fuel cells during startup and shutdown processes: Causes, consequences, and mitigation strategies. Journal of Power Sources 205, 10–23 (2012).Fuel Cell Tech Team Accelerated Stress Test and Polarization Curve Protocols for PEM Fuel Cells. Energy.gov https://www.energy.gov/eere/fuelcells/downloads/fuel-cell-tech-team-accelerated-stress-test-and-polarization-curve.Randrianarizafy, B. Multi-physics modeling of startup and shutdown of a PEM fuel cell and study of the carbon support degradation : mitigation strategies and design optimization. (Université Grenoble Alpes, 2018). Figure 1

The relation between nanotube diameter, length and surface area and pore volume of multi-walled spiral halloysite nanotubes: A theoretical study

Halloysite (Hal) is a natural clay mineral with nanotube structure. Due to their outstanding specific surface area, loading capacity and selective adsorption ability, Hal have been widely used in the fields of catalysis, adsorption, drug loading and releasing. However, the loading ability of Hal from different halloysite deposits still varies in a large range. The relation between the microstructure properties of Hal and the intrinsic parameters such as length (L), inner/outer diameter (Dinner/Douter) of halloysite nanotubes (HNTs) is still obscure. In this study, we constructed the atomic structures of several multi-walled spiral HNTs with diameters (10–40 nm) in the range of the real size of Hal, and calculated their specific surface area (S) and pore volume (V) to compare with experimental results. By comparing the difference between the calculated values and the theoretical values (based on simple mathematics), the relation between the S/V of HNTs and its Dinner/Douter and L is established using modified equations. The equations were applied to deduce the theoretical values of the specific surface area and pore volumes of HNTs in a wide range of inner/outer diameter (10–200 nm) and length (100–5000 nm). Notably, while the experimental surface area are highly consistent with the theoretical values, the experiment pore volume are mostly lower than the theoretical values, which indicates that the lumen space of HNTs from different deposits are blocked in different degrees by the associated minerals and impurities. It is expected that, in addition to traditional physicochemical purifications, the removal of lumen impurities can help to revive the lumen loading ability of HNTs upto their theoretical limits.

Experimental study of bubble size distribution in bubbly and bubbly-to-slug transition flow

The current work experimentally investigates the evolving characteristics of bubble size distribution (BSD) in bubbly and bubbly-to-slug transition flow in a 25.4 mm inner diameter pipe. Four-sensor conductivity probes used in present research enables accurate acquisition of bubble chord length in the flows with void fraction varying from 0.1 to 0.6. The flow regime transition is implemented by increasing superficial gas velocity while keeping superficial liquid velocity constant. Six right-skewed probability distribution functions (PDFs) commonly used for predicting bubble chord length distribution (CLD) are selected and used to fit the chord length data. The goodness of fit for all PDFs is evaluated by R-square, root-mean-square error (RMSE) and corrected Akaike information criterion. The results show that the PDF which reasonably fits the CLD in bubbly flow fails to fit the CLD in bubbly-to-slug transition flow. The evolving characteristics of CLD in flow regime transition process are qualitatively and quantitatively discussed based on bubble coalescence and break-up mechanisms. It is found that the invalidation of uniform morphology assumption and different mechanisms of bubble coalescence and break-up may result in the failed fitting. To properly predict real bubble size distribution (BSD) in bubbly-to-slug transition flow from CLD, an analytical backward transformation method is proposed to relate the CLD to BSD based on the bubble geometrical characteristics in the transition flow. The predicted BSD can be applied to calculate the interfacial area concentration (IAC) in the transition flow. The calculated IAC shows good agreements with experimental data which demonstrates the validity of predicted BSD in the transition flow.