bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Radial Forces and Pressure Fluctuations Measurement at Off-Design Conditions on a Model Scale Pump-Turbine
Authors: Novotný V , Habán V , Skoták A , Loub R
Published: December 2019

The main challenge in the pump-turbines development are hydraulic instabilities in the partial loads in both pumping and generating mode. For the mechanical design of the pump-turbine shaft and bearings, it is necessary to know the magnitude of the dynamic radial forces caused by these instabilities. The radial force magnitude is usually determined on the basis of head and the runner dimensions. The paper focuses on the comparison of the empirical approach to the radial forces and the measurement on the model scale pump-turbine that was carried out in the Litostroj Engineering hydraulic laboratory in Blansko, Czech Republic. There were six strain gauges mounted on the bearing support to monitor the radial forces. In the pumping mode two distributor openings were measured. In the generating mode eight distributor openings were measured with the focus on the S-shaped curves region in the characteristic. Additionally, there were pressure gauges installed in the vaneless gap between the distributor and the runner to monitor the pressure fluctuation and potential presence of rotating stall. The appearance of rotating stall was connected to the magnitude of dynamic radial force.
Study of hydrofoil boundary layer transition using different turbulence models
Authors: Ye C L , van Esch B P M
Published: December 2019

Boundary layer transition is one of the key factors affecting the hydrodynamic characteristics of hydrofoil. In order to explore the capability of a transition model coupled to different turbulence models in the prediction of hydrofoil boundary layer transition, the flow field around the NACA0009 blunt-edge hydrofoil at 0°angle of attack was calculated using γ-Reθt transition model coupled with SST, SST-DES, SST-SAS, SST-DDES turbulence models. The characteristics of the hydrofoil boundary layer at ReL=2*106 are analysed. The experimental data and numerical calculation results are compared. The results show that the four turbulence models differ quite a bit in simulating hydrofoil boundary layer transition at the same calculation conditions. The flow parameters of the hydrofoil boundary layer calculated by the transition model coupled with SST-DDES are closer to the experimental results.
Experimental and numerical analysis of cavitation and pressure fluctuations in large high head propeller turbine
Authors: Ocepek Matic , Peršin Zlatko , Kern Igor , Djelić Vesko , Muhič Simon , Lipej Andrej
Published: December 2019

In the last decades, Computational Fluid Dynamics (CFD) has played an important role in the numerical prediction of cavitation characteristics of different types of hydraulic turbines. Relative results of the characteristics curves for different hydraulic shapes can be predicted very accurately. Usually the prediction of the absolute values of various characteristics is still a challenge. In the paper, we would like to present the comparison between the results of the model testing and numerical analysis of the critical cavitation coefficient for propeller turbine and the results of pressure fluctuation for various operating regimes.

For the numerical analysis, the cavitation model is based on the barotropic state law which describes the density change when the pressure falls below the liquid saturation pressure. Barotropic means that the density depends only on the pressure. The model tests were performed according the IEC 60193 international standards.

The results of the research contain the diagrams with sigma break curves obtained with model test and numerical analysis for different operating regimes. Furthermore, a visual observation of the cavitation on the runner blades is also presented and compared with numerically obtained cavitation regions inside the computational domain. According to the pressure fluctuations full range of operating points has been analysed and are presented.
POD analysis of a vortex rope with transient boundary conditions
Authors: Urban Ondřej , Rudolf Pavel
Published: December 2019

The paper presents the results of a POD analysis of the flow in a swirl generator. The generator has two separate inlets – one straight axial inlet and one tangential inlet ended by a spiral case. This allows to set different operating points, which are in turn connected with different shapes of the vortex rope present in the flow field. In this case, the investigation is aimed at linearly varying flow rates at the boundaries, namely, the ratio of the tangential flow rate is increased from 40 % up to more than 80 % of the total flow rate, which is maintained constant. Substituting the POD modes into the energy equation provides additional insight into the energy fluxes between the modes and consequently into a major part of the turbulent flow energy cascade as the input data were gained from a CFD simulation using scale-resolving Stress-Blended Eddy Simulation model. The POD modes can be used to construct a simplified model of the vortex rope dynamics covering a wider operating range rather than just one point.
Properties of eco-friendly composites: palm kernel shell treated with sodium bicarbonate filled recycled high-density polyethylene
Authors: Husna Nadiatul , Lim Bee Ying , Voon Chun Hong , Teh Pei Ling
Published: December 2019

Palm kernel shells (PKS) treated by commercial sodium bicarbonate (SB) filled recycled high-density polyethylene (rHDPE) were produced using melt compounding. These environmentally friendly composites were prepared using twin-screw extruder by varying untreated and treated filler loading (0, 10 and 30 php). In this study, the tensile properties of untreated rHDPE/PKS and treated rHDPE/PKS-SB were investigated. The composites were subjected to tensile test and the fracture surfaces were observed under scanning electron microscope (SEM). The results showed that SB treatment improved the filler-matrix adhesion and interaction of composites. Meanwhile, the SEM micrographs on the fracture surfaces confirmed that SB treatment which may influence the tensile properties of these composites.
Synthesis of SiC nanowhiskers by microwave heating: effect of size of graphite
Authors: Kahar Suhaimi Mat , Voon Chun Hong , Lim Bee Ying , Arshad Mohd Khairuddin Md , Foo Kai Loong , Parmin Nor Azizah , Gopinath Subash C. B. , Ruslinda A. Rahim
Published: December 2019

Silicon carbide is a promising material for various applications, especially for applications in high frequency, high power and high temperature and harsh conditions such as highly oxidative and corrosive environment. Currently, silicon carbide is produced by conventional heating process. For silicon carbide nanomaterials, various methods have been attempted. In this study, SiC nanowhiskers were synthesized by microwave heating of blends of graphite and silica in the ratio of 3: 1. Graphite of two different size, namely micro graphite and nano graphite were used. The blends firstly prepared by ultrasonic mixing graphite and silica in ethanol followed by drying. The blends were then heated by using laboratory microwaves furnace to 1450 °C at heating rate of 20 °C/min for 20 minutes. Finally, the SiC nanowhiskers was characterized by using scanning electron microscope.
Injection Moulding Recommended Parameters Simulation Analysis of Rice Husk Composite
Authors: Jaya Haliza , Zulkepli Nik Noriman , Omar Mohd Firdaus , Rahman Shayfull Zamri Abd , Halim Khairul Anwar Abdul
Published: December 2019

Study of recommendation parameters for injection moulding process was carried out with aid of Autodesk Moldflow Insight. Rice husk filled low-density polyethylene was used as the raw material. Standard dog- bone shape mould with ASTM were used throughout the simulation analysis. The investigations were carried out on fill analysis, fill + pack analysis and cool analysis on injection moulded dog-bone shape. From the simulation analysis, the recommended parameters of the injection moulding process for rice husk composites were determined.
Mechanical properties of Sn based lead free solder under different temperature
Authors: Ismail Norliza , Bakar Maria Abu , Jalar Azman , Jasmin Muhammad Amer Hariths
Published: December 2019

In this study, effect of different temperature condition was investigated towards Sn-3.0Ag-0.5Cu (SAC305) solder wire. Tensile test with 0.1 mms−1 strain rate was performed at room temperature (25°C), 60°C, 120°C and 150°C chamber condition. Mechanical properties of SAC305 solder wire were evaluated from stress-strain curves which focused on yield stress, ultimate tensile stress (UTS) and elongation. From the stress-strain curves, there are exhibit the dynamic softening behavior for investigated solder wire. The higher temperature applied during the tensile test, induced the reduction of yield stress and UTS properties. However, elongation properties varied with the temperature condition. Highest percentage of elongation have been indicated at temperature 120°C. Therefore, different temperature conditions applied during tensile test have significant effect to the evaluated mechanical properties of SAC305 solder wire.
Morphology and biodegradability of microcrystalline cellulose / chitosan films
Authors: Chie Song Cheah , Wahab Mohamad Kahar Ab
Published: December 2019

The microcrystalline cellulose (MCC) chitosan film was produced through solution casting with different composition of chitosan and different plasticizers. Glycerol and polyethylene glycol (PEG) was used as a plasticizer in the MCC/chitosan film. Several testing on the biodegradability were conducted such as scanning electron microscope (SEM), moisture absorption and soil burial test. Results show that addition of plasticizer able to improve the miscibility of chitosan on the MCC film. According to moisture absorbtion and soil burial test, the addition of plasticizer showed the MCC/chitosan films were better in water resistance due to the plasticizer was able to facilitate the dispersion of chitosan in MCC films. The morphological analysis also found out that better interaction between MCC and chitosan when polyethylene glycol and glycerol was used as plasticizers in the films.
Thermoplastic Polyurethane (TPU) / Organo- fluoromica Nanocomposites for Biomedical Applications: In Vitro Fatigue Properties
Authors: Osman Azlin Fazlina , Martin Darren James
Published: December 2019

Poly(dimethylsiloxane) (PDMS) / poly(hexamethylene oxide) (PHMO)-based thermoplastic polyurethane (TPU) nanocomposite was investigated for potential use in biomedical application. Studies on the in vitro fatigue behaviour of the TPU and TPU nanocomposite (under physiological saline solution, 37°C conditions) were highlighted in this article. The data were compared with those of commercially available silicone elastomer (Nusil MED 4860). Results indicated that the TPU nanocomposite (2MED-C (2HM)) had greater fatigue properties than the virgin TPU, which provide strong evidence of its greater capacity to withstand cyclic forces than the host TPU when exposed to physiological fluid. This was caused by the presence of well dispersed and impermeable organofluoromica platelets in the TPU matrix resulted in more tortuous path for the physiological fluid diffusion, thereby decreasing the fluid permeability of the polymer. Eventhough the silicone elastomer has lesser hysteresis than the virgin TPU and TPU nanocomposite, its fatigue strength is much lower than those of the TPU nanocomposite. The findings revealed the potential of PDMS/PHMO based TPU nanocomposite to replace silicone elastomer as biomaterial, particularly for implantable biomedical device application.
Corrosion Assessment of Sn-0.7Cu Lead-Free Solder in 1 M Hydrochloric Acid
Authors: Cong Tan Xing , Mohamad Ahmad Azmin , Nazeri Muhammad Firdaus Mohd
Published: December 2019

The corrosion performance of Sn-0.7Cu solder alloy is investigated in 1 M Hydrochloride acid by means of potentiodynamic polarization technique at the scan range of -2VSCE to 1 VSCE was applied to the sample at the scan rate of 1mV/s. Supporting morphological analysis was done by using Scanning Electron Microscope while phase analysis was confirmed by using X-ray Diffraction analysis. Morphological analysis showed two type of oxide layer has formed as corrosion product, which are compact oxide layer and loose rod-like oxide layer after corrosion analysis which confirmed to be SnO and SnO2. This indicate that complete protection from further corrosion was impossible due to the incomplete passivation layer formation.
Determination of the strength of the flat wagon fitting stops by elastic viscous interaction with fittings of the tank container
Authors: Fomin O , Lovska A , Bazyl L , Radkevych O , Skliarenko I
Published: December 2019

The article highlights the peculiarities of determining the strength of the flat wagon fitting stops, taking into account the viscous and elastic-viscous interaction with the fittings of the tank container. Mathematical modelling was performed to determine the dynamic load of the flat wagon with tank containers in the case of shunting collision taking into account elastic, viscous and elastic-viscous interaction between fittings and fitting stops. It is established that the elastic interaction does not compensate for the dynamic loads acting on the flat wagon in the case of shunting collision. Accelerations acting on the flat wagon with the tank containers do not exceed the normative values taking into account movement of the fittings relative to the fitting stops by viscous and elastic-viscous interaction. It was established that the strength of the bearing structure of the flat wagon and fitting stops is provided by viscous or elastic-viscous connections between fittings and fitting stops, taking into account the possible movements of tank containers in relation to the frame. The conducted researches will provide efficiency increase of combined transportations and develop recommendations for designing modern constructions of railway rolling stock.
Modeling the Dynamic Response of Railway Track
Authors: Kurhan D , Kurhan M
Published: December 2019

The authors developed a model based on the dynamical theory of elasticity, which allows us to describe the dynamic equilibrium of strains of the railway track layers. The model of the stress-strain state for the railway track consists in a combination of the geometry equations of the outline of a part in the system’s space, involved into interaction at a given time and the equations of the dynamic equilibrium of its deformation. Considering the obligation to register the course of the process in time, for each time step of integration the outline of the strains propagations front is determined. The strains propagations front is described by the equations of propagation in the material of the elastic spatial wave of oscillations. It allows determining complete spatial-temporal account of the deflection dynamics of the rail support, which enables the execution of calculations, including for conditions of fast-speed and high-speed trains. With the application of the developed model, a number of scientific and practical problems were solved.
Synthesis of quasioptimal control of the technical systems with the direct current drive
Authors: Loveikin V S , Romasevych Yu O , Korobko M M
Published: December 2019

The paper presents an approximate solution of the optimal control problem of the technical system driven by the direct current motor. The braking mode of the system is under consideration. The optimization criterion was a nonlinear integral functional, which reflects the root-mean-square value of the electric drive power during the system’s braking mode. It was found, that the necessary condition of the criterion minimum – Euler-Poisson equation – is a sixth-order nonlinear differential equation. It is impossible to find its analytical solution. In order to find the approximate solution a direct variational method was applied. Proper selection of the class of the basis functions allowed to reach the absolute minima of the terminal criteria and meeting the boundary conditions of the system’s movement. The first provides decreasing of the dynamical forces in the system transmission; the latter is connected with the statement of the problem. Among the class of functions, the one was found, which minimizes the integral criterion. In order to illustrate the approximate solution of the optimal control problem, the plots have been built. They show the smoothness of the system movement and practicability of the obtained result. All calculations have carried out in an analytical form.
Predictive assessment of change of basic geometric characteristics of rail track during the operation
Authors: Potapov D O , Vitolberg V G , Malishevskaya A S , Plis P V , Trishchun R M
Published: December 2019

The frequency and scope of scheduled preventive work depends on multiple factors: type and design of the upper track structure, plan and profile of the track, quality of the track maintenance, as well as operational, climatic and topographical conditions. Also, each type of work is affected by these factors in different ways. In addition, the factors themselves are unstable along the length of the track. Therefore, under different operating conditions, the frequency and scope of routine track maintenance are different. Since currently regulatory technical documents and domestic scientific sources contain no requirements for high-speed sections of the Ukrainian railways and, thus, a problem of organization of control of the track state in these operating conditions appears. The methodology for determining the scope and frequency of the scheduled preventive routine track maintenance work is proposed. The method is based on the use of the normal law of distribution of frequency and depth of the respective geometrical irregularities of the railway track. The maximum effect of the proposed method can be achieved through the use of modern track geometry cars with an automated data collection and interpretation system that are predominantly used in the high-speed traffic areas.
Determination method of dynamic characteristics of mobile terrestrial robotic complex manipulator
Authors: Strutynskyi S V
Published: December 2019

A method for determining the dynamic characteristics of the mobile terrestrial robotic complex manipulator is developed. A new concept for finding dynamic characteristics is proposed. It involves determining the manipulator displacement during its “quasi-rigid” movement along with the chassis along the road surface with isolated inequality through a rectangular projection. The manipulator is considered to be undeformed and its position relative to the chassis unchanged. Having considered “quasi-rigid” displacement of the manipulator, the dynamic loads acting on it are defined. At the same time, dynamic deformations of the manipulator corresponding to the “deformation” movement of the manipulator elastic system relative to its position corresponding to the “quasi-rigid” displacement are considered. Based on the proposed concept, a method for determining the dynamic characteristics of the manipulator was developed. It involves the development of a mathematical model of the manipulator when presenting it through a multi-mass dynamic system. The system of dynamics equations is presented as a structural mathematical model by means of which the dynamic characteristics of the manipulator corresponding to the robotic complex displacement along the road with a single irregularity are found. The coefficients of dynamic loads in the elastic system of the manipulator are determined by simulation.
Research into the track/vehicle interaction processes for underground railways
Authors: Vitolberg V G , Bugaets N V , Malishevskaya A S , Shumyk D V , Yakovenko Y S
Published: December 2019

The article deals with determination of dynamic forces in interaction between a rail vehicle and underground track for working out recommendations in terms of a longer service life of the permanent track without extra charges. The issue is of importance for enterprises under limited resources. The research was conducted with mathematical model methods for the vehicle/track dynamic system (the principles were developed earlier), as the experimental work in the underground tunnels was complicated by intensive train traffic during a day. A special feature of the research was consideration of a rail as a bar rested on discrete elastic-dissipative supports in a design diagram of the vehicle/track dynamic system. Thus, the authors established the effects of unequal elasticity of the track rail support on the value of vertical dynamic forces when a metro coach moves on the track. In particular, the dependencies of dynamic factors and amplitude ratios of vertical forces on speeds of metro coaches along the discrete elastic- dissipative track were obtained. An exceptional value of the research is consideration of both vertical and horizontal lateral forces on the vehicle/track interaction. It allowed the authors to define the value of vertical and horizontal lateral forces which occurred when metro coaches moved along straight and curved sections of the track according to the speed and curve radius.
Theoretical analysis of RC beams reinforced with high strength rebar’s and steel plate
Authors: Bobalo Taras , Blikharskyy Yaroslav , Kopiika Nadiia , Volynets Mykhailo
Published: December 2019

The article introduces the comparative results of the deformability and fracture resistance of steel reinforced concrete beams with combined reinforcement obtained on the basis of laboratory tests with the results of computer-aided mathematical modelling of such structures. The results were compared for the purpose of mathematical model testing and its further usage in the study of the optimal reinforcement percentage in steel reinforced concrete beams with combined reinforcement. Results obtained on the basis of the proposed mathematical model show sufficient correlation with the experimental data up to the stage of structure strength exhaustion. As the result it enables to evaluate the features of destruction of the tested samples with the sufficient accuracy, namely, their load-carrying capacity, cracks formation, to analyze stresses in both steel bars and tapes, monitor deflections and deformations during the loading of the tested beams. Deviation of the experimental values for steel reinforced concrete beam with the combined reinforcement from the data obtained according to mathematical model: up to 5.0% for fracture resistance; up to 14.3% for deformability.
Influence of load level during strengthening of reinforced concrete beams on their reliability
Authors: Khmil Roman , Tytarenko Roman , Blikharskyy Yaroslav , Vashkevych Rostyslav
Published: December 2019

The main purpose of article is to study the influence of load level on the reliability of non-damaged reinforced concrete beams with rectangular cross-section during strengthening by adding stretched steel reinforcement. On the basis of real samples testing of the existing and advanced methods of reliability estimation (depending on the variant of random parameter of the load level at the strengthening moment), adapted to the national norms of reinforced concrete structure design, the recommended value of failure-free probability P(β) – within ranges 0.999624-0.999758 and 0.999606-0.999775 (for two of considered variants, respectively). The comparative analysis of obtained results is conducted depending on the additional steel bar diameter (Ø10 mm, Ø12 mm, Ø14 mm) and load level at the strengthening moment (0.0×Mult, 0; 0.3×Mult, 0; 0.5×Mult, 0; 0.75×Mult, 0, where Mult, 0 is bearing capacity of non-strengthened beam). Practical utility of the study results could be associated with the possibility of usage both existing as well as developed methodology to evaluate reliability for design of bended reinforced concrete elements, strengthened with additional stretched steel rebar subjected to load (simulation of the actual element performance during strengthening), especially in the case of proving reliability levels of its design.
Theoretical calculation method for crack resistance of jacketed RC columns
Authors: Krainskyi Pavlo , Vegera Pavlo , Khmil Roman , Blikharskyy Zinoviy
Published: December 2019

Theoretical method of crack width calculation in jacketed reinforced concrete columns is described and validated in this paper. The total number of tested columns was 12. The initial load applied to the column before strengthening was the main variable parameter in this test. Columns were strengthened by reinforced concrete jacketing after loading. Two RC columns were tested without strengthening to serve as reference samples. Two RC columns were strengthened with RC jacketing without any initial loading to determine maximum strengthening effect. Loading was applied in steps. This study is the calculation of the crack resistance parameters RC columns, strengthened by RC jacketing under the influence of various initial loads. Crack width and pattern were checked after each step. The maximum allowed crack width for test samples was adopted as wmax
= 0.3 mm. The rest eight samples were preliminarily loaded to 0.3; 0.5; 0.7 and 0.9 of reference columns bearing capacity, strengthened and tested to failure. The results of theoretical calculation deviate from test results by 13.6…27.9%.
Exact solution of buckling problem of the column loaded by self-weight
Authors: Krutii Yu , Vandynskyi V
Published: December 2019

This work proposes the new method of investigation the buckling problem of the uniform column under the axial distribution load, which presented by self-weight. The new method is based on the exact solution of the appropriate differential equation for the buckling of a column. The solution is expressed with dimensionless fundamental functions and initial parameters. Due to the exact solution, the formulas in an explicit form for variables of the state of a column – deflections, angular displacement, bending moment and transverse force – were defined. They generally define the stress-strain state of the column Due to the dimensionless nature of the fundamental functions the analytical form of load is defined. That has limited the problem of determination of critical load to determination the unknown non-dimensional buckling coefficient through characteristic equation. An example of determining the buckling coefficient for a hinged column was considered. The values of buckling coefficient for most popular design schemes are given. The proposed method does not require discretization od scheme and is a real alternative to applying approximate methods when solving stability problems of this class.
Stability of light steel thin-walled structures filled with lightweight concrete
Authors: Semko V O , Mahas N M , Fenko O G , Sirobaba V O , Hasenko A V
Published: December 2019

The article presents the results of stability calculation of reinforced concrete columns using light steel thin-walled structures investigation. Two steel thin-walled profiles of type “C” or “∑” were used as the steel shell of such columns. The profiles were combined in the form of a box section with bolts. To increase the stability of the shell, the inner cavity was filled with concrete with lightweight aggregates. Technique of steel thin-walled elements stability calculation with consideration of concreting and joint work of the whole structure involves two types of calculation: for central compression and for joint action of compression and uniaxial bending. To verify the analytical calculations, a computer simulation was performed, which proved the correctness of the theoretical calculations and made it possible to clearly observe the different forms of column stability loss at different coefficients of overload. It was found that the increase of bearing capacity due to the thickness of the profile varies within 2-10%. For smaller profiles this difference is significant (10-23%), and for larger profiles - smaller (5-8%). This is due to the complexity of the manufacturing technology and the cost of materials.
Practical experience of construction of concrete pavement using non-conditional aggregates
Authors: Krivenko P , Kovalchuk O , Boiko O
Published: December 2019

The ways of involving iron ore tailings in road construction are shown in this paper on example of alkali-activated slag cements used as a binding material. The results of the study showed that in case of the alkali-activated slag cements the compacted concrete mixtures for bases could incorporate up to 40 % of iron ore tailings, and with addition of up to 10 % of fly ash by mass – up to 60 % by mass with providing the required compressive strength (>2 MPa) and coefficient of softening (in water) (not lower than 0.8). The results suggested to show that with increase in quantities of the alkaline component the strength tended to increase, and that addition of fly ash was favourable in terms of consistency of the concrete mixture and time of workability retention. The concrete with 100 % replacement of fine aggregate by iron ore tailings exhibited compressive strength of 30 MPa and the concrete mixture had a consistency of classes S3-S4 as per EN 206-1:2000. This concrete mixture of optimal composition was used as paving in the construction of a pilot road (length 50 m, width 4 m, and thickness 0.3 m) in Qianxi (Tianshan, P.R.China).
Alkali-activated Portland cement with adjustable proper deformations for anchoring application
Authors: Krivenko P V , Rudenko I I , Petropavlovskyi O M , Konstantynovskyi O P , Kovalchuk A V
Published: December 2019

The application of alkali-activated Portland cement (hereinafter AAPC) for anchoring grouts was investigated with obtaining of non-shrinking high performance cementing systems. The AAPC system “ordinary Portland cement clinker – sodium metasilicate” was modified by the complexes of mineral and organic compounds to ensure specified properties of anchoring grouts. It was revealed that the most effective multifunctional additives are represented by the system “salt-electrolyte – surfactant”. Alongside with slowing down of AAPC paste setting time, the effect of compensated shrinkage of AAPC mortar, i.e. expansion within 0.062 mm/m and slight shrinkage within 0.017 mm/m, was ensured when Na2SO4 and NaNO3 were used in the mentioned system respectively. The effect of compensated shrinkage is explained by greater crystallization of hydrosilicates and hydroaluminates, additional formation of sulfate-containing sodium-calcium hydroaluminate (for Na2SO4-based system) and crystalline calcium hydronitroaluminate (for NaNO3-based system). The advantages of the modified AAPC for anchoring application are indicated in the paper.
Research of plywood quality by acoustic methods
Authors: Pinchevska O O , Baranova O S , Gorbachova O Y , Gandzuk V M
Published: December 2019

Traditionally, for composite materials, glued wood and solid wood are used nondestructive methods of control that take into account the specific features of the object. Plywood is a non-metal anisotropic material of complex structure, so most non-destructive testing methods, such as magnetic and eddy current methods are excluded. For choosing a method, it should also be borne in mind that plywood is a large product and may have significant size defects. The shock method is easier to implement than other non-destructive testing methods, so it can be considered effective for plywood defectoscopy. The existing classical shock method is carried out by the absolute values of the deviations of the characteristics of the oscillatory processes of the plywood. Changing the variable factors of plywood may reduce the accuracy of the device being implemented. Therefore, a technique for improving the shock method by measuring the relative characteristics of the oscillation process was developed. Comparison with the known, most accurate ultrasonic method of control revealed that the highest correlation with ultrasound has such a parameter of the shock sensor as the coefficient of harmonic distortion, which gives reason to recommend the shock method for determining the area defect plywood.
The factors defining the efficiency of earthed shields made of electroconductive cementing compositions for the electrocorrosion protection
Authors: Pluhin O A , Plugin D A , Kasianov V V , Skoryk O O , Nykytynskyi A V
Published: December 2019

The factors that define the efficiency of earthed coating shields made of the Portland cement-based electroconductive cementing composition were experimentally studied to provide the electrocorrosion protection. It was established that the current intensity is increased by the three orders of magnitude as the current flows through the water-saturated earthed coating shield made of the Portland cement-based electroconductive composition. This fact confirms the feasibility of the use of such shields to drain the leakage currents that are considerably increased achieving unsafe values especially in wet weather. It was also established that protective shield properties depend on the ratio of the contact area of the coating-shielded steel earth electrode to the area of entire coating shield. As this ratio is increased the intensity of the current flowing through the structure reinforcement and concrete is decreased and the intensity of current flowing through the earthed coating shield is increased. It confirms the efficiency of the use of earthed coating shields made of the Portland cement-based electroconductive compositions to provide the electrocorrosion protection caused by leakage currents, for example for such structures as railway d. c. current-electrified passenger platforms.
Calculations of exhaust emissions produced by vehicle with petrol engine in urban area
Authors: Šarkan B , Kuranc A , Kučera Ľ
Published: December 2019

The paper deals with the method of calculating exhaust emissions of a passenger vehicle during drive in urban area. For this calculation, a running test was conducted in which exhaust gas volume data and engine control data were recorded. The evaluated exhaust gas components are nitrogen oxide, hydrocarbon, carbon monoxide, carbon dioxide. The engine speed, intake air quantity, vehicle speed and intake air temperature were recorded from the engine control unit. The exhaust components are calculated in gram per kilometre of vehicle drive.
Movement analysis of the semitrailer with the tank-container at hard braking -the case study
Authors: Vrabel J , Skrucany T , Bartuska L , Koprna J
Published: December 2019

Transport of liquid, gaseous, powdered or granulated substances is an integral part of the industry in each country. This type of cargo is most often transported by companies that are a part of petrochemical, food or also other types of industry. Increased attention should be paid to transport of tank-vehicles and tank-containers from the point of view of road safety and environmental protection. The volume of such types of transport is growing every year. The extensive trend relates mainly to the developed world economies, which are experiencing economic growth, which includes also Slovakia according to the Statistical Office of the Slovak Republic. This article deals with evaluating the movement of semi-trailer trucks with a tank container during and immediately after hard braking. The movement of the semi-trailer truck with a tank container will be analysed and evaluated immediately after the vehicle is stopped. The movement of the vehicle will be analysed by video analysis. The focus is on analysing behaviour of the semi-trailer truck with a tank container during and immediately after braking. The article compares semi-trailer trucks with tank container with breakwater plates and tank containers without breakwater plates. An important feature of this comparison was processing of videos capturing these vehicles during hard braking in video analysis program.
Modeling sequencing batch reactor operational conditions depending on oxygen concentration
Authors: Łagód G , Piotrowicz A , Cel W , Zaburko J , Drewnowski J
Published: December 2019

Sequencing batch reactors (SBR) can be used as a fill-and draw activated sludge system for wastewater treatment with considerable operating flexibility and the possibility to conduct experiments under standard conditions and extreme case scenarios. Mathematical modeling and computer simulations provide an opportunity to implement existing wastewater processes in modeling software and evaluate different modifications at low costs and no disturbances for on-going processes of full scale WWTP. Additionally, the used model can be calibrated and validated against experimental data from laboratory scale devices. The aim of this study was to simulate the processes occurring in laboratory scale SBR under different aeration strategies. The results include the analysis of the adaptation period of the activated sludge biomass in the SBR, as well as the case of breakdown of treatment process due to stoppage of raw wastewater inflow and the interruption of the aeration and/or mixing. As a result, it can be stated that the oxygen transfer rate should be incorporated in the calibration of biological nutrient removal model in order to effectively visualize the individual contributions of each process.
Reduction of excessive heavy metals accumulation in drinking water with natural zeolites
Authors: Kujawska J , Wasag H
Published: December 2019

This paper reports on the study of heavy metal removal from groundwater intended for human consumption using natural aluminosilicates of the zeolite group. The natural zeolite material has been extracted from the Sokirnica deposit located in the Zakarpattia Region in Ukraine. The central focus of this study was the course of the heavy metal adsorption process itself, in which natural zeolites were applied for the removal of Cr, Cd, Ni and Pb ions from aqueous solutions in the presence of large amounts of Ca and Mg ions, competing for ion exchange sites. The capacity of zeolite as an adsorbent was assessed with the use of adsorption isotherms prepared for the heavy metals under tests, whereas the mathematical description of the process was provided by Freundlich and Langmuir isotherm equations. The results from the analysis confirm the high efficiency, and thus the applicability, of zeolite deposits in water filtration. The effective Cr, Cd, Ni and Pb removal rate from groundwater intended for human consumption was confirmed even when the content of these metals in water was exceeded by a factor of 10, compared to the permissible limits provided in legal regulations.
Static response of FGM porous rhombic conoidal shell
Authors: Ansari M I , Kumar A , Barnat-Hunek D , Łagód G
Published: December 2019

The porosity effect on static analysis of functionally graded porous doubly curved rhombic conoids was investigated. Porosities inside functionally graded materials can occur due to a technical issue during the fabrication process and lead to the occurrence of micro-voids in the materials. The porosity effect was accounted for using a modified power law. The presented mathematical formulation includes normal curvatures in displacement field, as well as cross curvature in strain-displacement field. The improvement in the 2D mathematical model enables to solve problems of moderately thick FGM porous conoids. The feature that distinguishes the presented shell from other is that the maximum transverse deflexion does not occur at its centre. The improved mathematical model was executed in finite element code. The obtained numerical results were compared with the results available in the literature. Once validated, the current model was employed to study the effect of porosity, skew angle, boundary condition, volume fraction index, loading pattern and other geometric parameters.
The comparison of automatic traffic counting and manual traffic counting
Authors: Paľo J , Caban J , Kiktová M , Černický Ľ
Published: December 2019

The main purpose of traffic surveys is to know current state of transport and for design and solution of transport in the future. For collecting traffic data, traffic surveys are carried out which consist in counting the number of vehicles of different categories. There are many ways of collecting traffic data. This paper deals with manual counting and with automatic vehicle counter. Two traffic surveys were made and results from manual counting and automatic counting were compared. The aim is to find and describe advantages and disadvantages of selected types of traffic counting.
Two-dimensional metal-organic frameworks for energy-related electrocatalytic applications
Authors: Chen Sheng , Wu Deeson , Zhao Chuan
Published: December 2019

In this short perspective we examine recent developments in the design, synthesis and use of metal-organic frameworks (MOFs) for electrocatalytic applications. We discuss the inherent challenges and limitations that continue to plague conventional MOFs and novel strategies for overcoming them. In particular we focus on the growing interest in two-dimensional MOFs as a practical HER/OER/NRR/CO2RR catalyst. We also consider its exciting value as a tool for probing the underlying reaction mechanism and catalytic function of various metals.
End-Stage Kidney Disease Is Overlooked as a Proximate Cause of Death at Autopsy
Authors: Reynolds Meredith A , Henriksen Kammi J , Chang Anthony
Published: December 2019

Objectives

To determine how often end-stage kidney disease (ESKD) is implicated as a cause of death (COD) at autopsy.

Methods

We searched our autopsy database (2007-2017) using queries “end-stage renal disease,” “end-stage kidney disease,” “ESRD,” “chronic renal disease,” and “chronic kidney disease.” Final diagnosis and summaries were reviewed to determine if ESKD was appropriately correlated with the COD. Cases in which the COD was unrelated to kidney function were excluded.

Results

Eighty-five patients with a history of ESKD and histologic confirmation thereof were identified. Their CODs were cardiovascular (36%), infection/sepsis (41%), pulmonary (6%), gastrointestinal/hepatic (2%), central nervous system (3%), other systemic disease (7%), and unspecified (5%). ESKD was implicated as a contributing COD in 24 (28%) cases.

Conclusions

ESKD is often overlooked at autopsy, particularly in patients with cardiovascular or infectious disease. Accurate documentation of ESKD contributing to mortality is important for education, counseling, record maintenance, and directing research efforts.
Hospital Records of Pain, Fatigue, or Circulatory Symptoms in Girls Exposed to Human Papillomavirus Vaccination: Cohort, Self-Controlled Case Series, and Population Time Trend Studies
Authors: Thomsen Reimar Wernich , Öztürk Buket , Pedersen Lars , Nicolaisen Sia Kromann , Petersen Irene , Olsen Jørn , Sørensen Henrik Toft
Published: December 2019

Human papillomavirus (HPV) vaccination has been associated with subsequent diffuse symptoms in girls, reducing public confidence in the vaccine. We examined whether girls have nonspecific outcomes of HPV vaccination, using triangulation from cohort, self-controlled case series (SCCS), and population time trend analyses carried out in Denmark between 2000 and 2014. The study population consisted of 314,017 HPV-vaccinated girls and 314,017 age-matched HPV-unvaccinated girls (cohort analyses); 11,817 girls with hospital records (SCCS analyses); and 1,465,049 girls and boys (population time trend analyses). The main outcome measures were hospital records of pain, fatigue, or circulatory symptoms. The cohort study revealed no increased risk among HPV vaccine-exposed girls, with incidence rate ratios close to 1.0 for abdominal pain, nonspecific pain, headache, hypotension/syncope, tachycardia (including postural orthostatic tachycardia syndrome), and malaise/fatigue (including chronic fatigue syndrome). In the SCCS analyses, we observed no association between HPV vaccination and subsequent symptoms. In time trend analyses, we observed a steady increase in these hospital records in both girls and (HPV-unvaccinated) boys, with no relationship to the 2009 introduction of HPV vaccine to Denmark’s vaccination program. This study, which had nationwide coverage, showed no evidence of a causal link between HPV vaccination and diffuse autonomic symptoms leading to hospital contact.
LiPLike: towards gene regulatory network predictions of high certainty
Authors: Magnusson Rasmus , Gustafsson Mika
Published: December 2019

Motivation

High correlation in expression between regulatory elements is a persistent obstacle for the reverse-engineering of gene regulatory networks. If two potential regulators have matching expression patterns, it becomes challenging to differentiate between them, thus increasing the risk of false positive identifications.

Results

To allow for gene regulation predictions of high confidence, we propose a novel method, the Linear Profile Likelihood (LiPLike), that assumes a regression model and iteratively searches for interactions that cannot be replaced by a linear combination of other predictors. To compare the performance of LiPLike with other available inference methods, we benchmarked LiPLike using three independent datasets from the Dialogue on Reverse Engineering Assessment and Methods 5 (DREAM5) network inference challenge. We found that LiPLike could be used to stratify predictions of other inference tools, and when applied to the predictions of DREAM5 participants, we observed an average improvement in accuracy of >140% compared to individual methods. Furthermore, LiPLike was able to independently predict networks better than all DREAM5 participants when applied to biological data. When predicting the Escherichia coli network, LiPLike had an accuracy of 0.38 for the top-ranked 100 interactions, whereas the corresponding DREAM5 consensus model yielded an accuracy of 0.11.

Availability and implementation

We made LiPLike available to the community as a Python toolbox, available at https://gitlab.com/Gustafsson-lab/liplike. We believe that LiPLike will be used for high confidence predictions in studies where individual model interactions are of high importance, and to remove false positive predictions made by other state-of-the-art gene–gene regulation prediction tools.

Supplementary information

Supplementary data are available at Bioinformatics online.
Niche partitioning within a population of sea snakes is constrained by ambient thermal homogeneity and small prey size
Authors: Goiran Claire , Brown Gregory P , Shine Richard
Published: December 2019

In many populations of terrestrial snakes, the phenotype of an individual (e.g. body size, sex, colour) affects its habitat use. One cause for that link is gape limitation, which can result in larger snakes eating prey that are found in different habitats. A second factor involves thermoregulatory opportunities, whereby individuals select habitats based upon thermal conditions. These ideas predict minimal intraspecific variation in habitat use in a species that eats small prey and lives in a thermally uniform habitat, such as the sea snake Emydocephalus annulatus, which feeds on tiny fish eggs and lives in inshore coral reefs. To test that prediction, we gathered data on water depths and substrate attributes for 1475 sightings of 128 free-ranging E. annulatus in a bay near Noumea, New Caledonia. Habitat selection varied among individuals, but with a preference for coral-dominated substrates. The body size and reproductive state of a snake affected its detectability in deep water, but overall habitat use was not linked to snake body size, colour morph, sex or pregnancy. A lack of ontogenetic shifts in habitat use allows extreme philopatry in E. annulatus, thereby reducing gene flow among populations and, potentially, delaying recolonization after local extirpation events.