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Asphalt emulsion is a common material used for pavement base course stabilization, and cement is usually added as an active filler to improve the stability of asphalt emulsion mixtures further. However, using cement in these mixes has several drawbacks, including high material costs and environmental issues. On the other hand, asphaltenes is a waste by-product derived from the processing of Alberta oil-sands bitumen that could be used for the same purpose. This investigation compares the impact of cement and asphaltenes as additives to asphalt emulsion-stabilized layers. To compare the performance properties, cement- and asphaltenes-modified mixtures are prepared at different concentrations. The performance properties of the modified mixtures are investigated by conducting a series of tests including Marshall stability, indirect tensile strength, IDEAL-CT, and tensile strength ratio. In addition, to evaluate low-temperature cracking resistance of the mixtures, indirect tensile strength test is conducted at 0 °C and –10 °C.

In this study, the use of shear strength ratio (SSR) in analysing asphalt mixture’s susceptibility to moisture was investigated and verified. Three surface and two base mixtures were considered for...

Brick masonry does not exhibit much capacity to resist lateral loads and hence the masonry suffers heavy damage during earthquakes, which impart lateral loads to structures. In the Bhuj earthquake of Jan 26, 2001, that occurred in majority of masonry structures failed because they were built with un-reinforced brick masonry. The EBC code of practice for brick masonry, suggests the use of lintel band and roof band that introduce a rigid box-type behavior which will help the structure to improve its performance against seismic loads. But there are no Codal provisions for use of Rat-Trap bond masonry which has been found to possess good seismic resistance characteristics. Rat-Trap bond system consists of an array of headers and stretchers with bricks laid vertically on the edge to form a cavity within a set of two headers and two stretchers. In this investigation, an attempt has been made to study the behavior of un-reinforced Rat-Trap bond masonry of two categories viz., (i) with roof slab, and (ii) without roof slab. Shock-table tests on one-third scale masonry building models ( with and without roof slabs ) were carried out to study the behavior. The peak accelerations were recorded for each shock. The scaled bricks were obtained by cutting locally available bricks using special tools. The size of the masonry models was 2m x 1m x 1m. The amount of energy imparted during each shock was measured before total collapse both for Rat-Trap bond masonry models with and without roof slabs. The results of the tests revealed that the roof weight plays an important role in the design of Rat-Trap masonry systems subject to seismic loads.

Copper matrix composites (CMC) are frequently used in the automotive, aerospace, construction, and electrical-electronics industries. Properties such as low density, improved fatigue strength, high hardness, and high specific strength are the factors that make copper matrix composites important. The development of these factors is important for the industrial use of copper matrix composites. SiCp doped metal matrix composites have better mechanical properties than pure alloys. It is also known that Ti, B powder particle additives improve the mechanical properties of the main matrix. In this study, Cu hybrid composites reinforced with Ti–B-SiCp powders, which were not produced before, were obtained and their microstructure, density, hardness, and wear behavior were investigated. Composite materials produced by powder metallurgy method were prepared at 2–8 wt. % mixing ratios. Then each material was sintered at temperatures of 950–100-1050 °C. Microstructural images showed homogenous distribution in the composite material. The highest relative density of 93% was obtained in the composite material with a 2% reinforcement rate at 1050 °C. It was found that the hardness increased with the increase of the reinforcement rate up to 6 wt.% and then decreased after that. It was observed that the specific wear rate increased with the increasing reinforcement ratio. In addition, the lowest friction coefficient and wear temperature occurred at a sintering temperature of 1050 °C. In this study, it was reported that the sinter temperature value of 1050 °C is the optimum temperature value in terms of the tribological and mechanical performance of the materials.

Purpose The boundary-layer analysis is required to reveal the fluid flow behavior in several industrial processes and enhance the products’ effectiveness. Therefore, this research aims to investigate the buoyancy or mixed convective stagnation-point flow (SPF) and heat transfer of a micropolar fluid filled with hybrid nanoparticles over a vertical plate. The nanoparticles silver (Ag) and titanium dioxide (TiO2) are scattered into various base fluids to form a new-fangled class of (Ag-TiO2/various base fluid) hybrid nanofluid along with different shape factors. Design/methodology/approach The self-similarity transformations are used to reformulate the leading requisite partial differential equations into renovated non-linear dimensionless ordinary differential equations. The numerical dual solutions are gained for the transmuted requisite equations with the help of the bvp4c built-in package in MATLAB software. The results are validated by comparing them with previously available published data for a particular case of the present study. Findings The impact of various pertaining parameters such as nanoparticle volume fraction, material parameter, shape factor and mixed convective on temperature, heat transfer, fluid motion, micro-rotation and drag force are visualized and scrutinized through tables and graphs. It is observed that dual or non-uniqueness outcomes are found for the case of buoyancy assisting flow, whereas the solution is unique in the buoyancy opposing flow case. Additionally, the fluid motion and micro-rotation profiles decelerate in the presence of nanoparticle volume fraction, while the temperature augments. Originality/value The mixed convective stagnation point flow conveying TiO2/Ag hybrid nanofluid with micropolar fluid with various shape factors is the significant originality of the current investigation where multiple outcomes are obtained for the assisting flow. The various base fluids such as glycerin, water and water–ethylene glycol (50%:50%) are considered in the present problem. The bifurcation values of the considered problem do not exist, probably because of various base fluids. To the best of the authors’ knowledge, this work is new and original which were not previously reported.

Aluminum alloys with electroplated coatings and copper plated in particular gained multiple applications. However, pre-zincate treatment often fails to provide the desired adhesion of the coating. We present the results of studying the effect of the electrolyte composition on the adhesion and other properties of the coating-base system. It is shown that an electrolyte with a reduced content of sulfuric and phosphoric acids can be used for anodizing and the oxide films formed during anodizing are stable in the usual copper-plating sulfuric acid electrolyte which eliminates contact exchange and increases adhesion. The use of a modern scratch-test method provides numerical determination of the values of adhesion of copper coatings. The adhesion value depends on the surface porosity of the oxide film and on the type of anodized alloys. The results can be used to improve the technology of applying copper coatings, both as an independent coating and as an underlayer in multilayer coatings.

В работе приведено численное моделирование пространственной задачи контактного взаимодействия ортотропных плит переменной жесткости с упругими основаниями. Используемая методика расчета пригодна в случае любых известных контактных моделей упругих оснований. В качестве примера приведены численные результаты для пространственно-неоднородных оснований типа упругих слоев постоянной и переменной толщины. Система интегро-дифференциальных уравнений, к которой сводится задача, решается численно, сочетанием методов конечных разностей типа сквозного счета и граничных элементов. Найдены прогибы, изгибающие моменты и распределения контактных давлений прямоугольной плиты переменной жесткости, полностью примыкающей к основанию. Приводится анализ влияния на напряженно-деформированное состояние плиты, изменения ортотропных свойств ее материала и степень неравномерной сжимаемости толщи грунта. Разработанная методика позволяет эффективно моделировать работу плитных фундаментных конструкций, когда необходим учет неоднородности грунтов сжимаемой толщи в пределах габарита зданий или сооружений. The paper presents a numerical simulation of the spatial problem of contact interaction of orthotropic slabs of variable stiffness with elastic foundations. The calculation technique used is suitable for any known contact models of elastic foundations. As an example, numerical results are given for spatially inhomogeneous foundations such as elastic layers of constant and variable thickness. The system of integrodifferential equations, to which the problem is reduced, is solved numerically by a combination of finite difference methods such as end-to-end counting and boundary elements. Deflections, bending moments and contact pressure distributions of a rectangular slab of variable stiffness, completely adjacent to the base, are found. An analysis of the influence on the stress-strain state of the slab of changes in the orthotropic properties of its material and the degree of uneven compressibility of the soil thickness is given. The developed technique makes it possible to effectively simulate the operation of slab foundation structures when it is necessary to take into account the heterogeneity of the soil of the compressible strata within the dimensions of buildings or structures.

In this work, we developed and validated a simple and selective method for the determination of titanium dioxide in double base solid (DB propellants). The method is based on complex formation of T...

Obtaining cheap and high-quality dry lubricant compositions based on local raw materials for stretching wires in the technology of obtaining small-sized wires from large-diameter wires. Dry lubricant obtained on the basis of local cheese is used for processing and drawing metals prepared from the following components: sodium soap, natriy sulphate Na2SO4 - 5.0-20.0; bura Na2B4O7·10H2O - 0.1-5.0 and talc. At present, the pilot-test work was carried out at a private company "DAVR METALL" in Namangan.

When two bodies interact in contact, self-oscillations or relaxation vibrations can occur, which are vibrations of parts of bodies relative to each other. The study of the processes occurring in the zone of an elastic tire interaction with a solid support base is of particular interest, since they directly affect the safety of movement of wheeled vehicles. The aim of the work is to study the conditions for the occurrence of self-oscillating processes in the zone of interaction of an elastic tire with a solid support base in three rolling modes: traction, driven, and braking. It has been established that the appearance of a self-oscillating mode in the zone of interaction of an elastic tire with a solid support base is a useful diagnostic feature providing recognition of the development of the process of losing adhesion of a wheel with a support base when the rear axle skids at early stages.

The paper presents the study on the identification of patterns of coloring of a basic glass matrix and enamel coatings based on it in the system R2O–ВаО–ZnO–Al2O3–В2О3–TiO2–SiO2 by a number of ionic dyes. Regardless of the dye content, ionic dyes give the same color tone to both glasses and coatings based on these glasses as follows: CuO (1.0–3.0 wt.%) =489–494 nm (blue-green), Fe2O3 (0.5–2.0 wt.%) =575–585 nm (yellow), K2Cr2O7 (0.5–2.0 wt.%) =570–576 nm (yellow-green), CoO (0.5–1.0 wt.%) =441–463 nm (blue-violet), and NiO (0.5–1.0 wt.%) glass=559'–571' nm, coatings=598–629 nm (brown). It is shown that according to the degree of color intensity of glasses and coatings based on them, the dyes are arranged in the following sequence: CoO>NiO>CuO>K2Cr2O7>Fe2O3.. The research was conducted using a special computer program COLOR GLASS. The established patterns are used in the development of lead-free glass enamels for jewelry and decorative products.

The Sentaurus TCAD software package is widely used in the modeling of semiconductor optoelectronic devices. The main part of simulating solar elements is creating a correct geometric model. A geometric model can be built using the SDE module in two different ways, i.e. by writing code or using standard shapes in a graphical environment. Creating complex structures using simple shapes is time-consuming and labour intensive. Therefore, this paper provides data on how to develop algorithms using geometric models of complex structural solar cells. A universal algorithm has been developed for creating a geometric model of solar cells with a sinusoidal p-n junction and a rear multiple structure. Using these algorithms, it is possible to create geometric models of various solar cells from simple to complex structures. By applying this algorithm, the authors studied the dependence of photoelectric parameters of the p-n and n-p junction silicon solar cells on their thickness in order to find the optimum thickness for both structures. It has been found, that the optimum thickness was equal to 256 μm for p-n junction and 75 μm for n-p junction silicon solar cell. The maximum efficiency of p-n junction silicon solar cell is 1.4 times greater than that of n-p junction solar cell in their optimum thickness.

In the work, the regularities of the process of sorption of copper and nickel ions from model solutions by low-base anionites containing coordination secondary groups are investigated. The main kinetic and concentration coordination characteristics of the process of complexation of copper and nickel ions with ligand groups of a low-base sorbent are determined.Potentiometric titration shows that anionite contains low-base functional groups, the pK of which is equal to 7.2.It is established that the process of sorption of copper ions by low-base macroporous anionite is characterized by a high initial rate and rapid achievement of equilibrium, which ensures absorption of copper ions about 70% of the equilibrium values in the first 10- 15 minutes.The main parameters of the sorption process are determined. Analytical description of sorption isotherm in coordinates of Langmuir equation is carried out. It was shown that due to high rates, the degree of extraction from solutions with a concentration of 10- 15 mmol/l under equilibrium conditions reaches 99.6-98.3%.Studies of the sorption process in a dynamic mode showed the possibility of separating heavy metal ions from aqueous solutions on new low-base anionites.

Fatigue failure of cement-stabilized macadam (CSM) base has always been a concern in highway construction. The microscopic initial defect is an important factor affecting its fatigue performance. T...

Приведено технико-экономическое обоснование повышения эффективности уплотнения покрытий и оснований за счет использования трехвальцевых дорожных катков тандемного типа. Выполнены расчеты, показывающие возможность последовательного увеличения вертикального нагружения вальцев катка по мере возрастания прочности уплотняемой поверхности в широких пределах (до 1,1 веса серийного катка) за счет применения дополнительной управляемой секции. Установлена возможность уменьшения числа проходов катка за счет увеличения количества его вальцев. Проведен технико-экономический расчет, подтверждающий целесообразность применения таких дорожных катков, выполненных на базе серийных двухвальцевых машин, которая обусловлена увеличением производительности в 1,27…1,5 раза. We present a highway impact study for increasing efficiency of compaction of coatings and bases through the use of three-roller tandem compactors. Calculations have been performed showing the possibility of a sequential increase in the vertical loading of the rollers of a compactor as the strength of the compacted surface increases over a wide range (up to 1.1 of the weight of a serial compactor) due to the use of an additional controlled section. The possibility of reducing the number of passes of the compactor by increasing the number of its rollers has been established. A technical and economic calculation was carried out confirming the feasibility of using such road compactors made on the basis of serial two- roller tandem compactors, which is due to an increase in productivity by 1,27…1,5 times.

This work was supported by King Abdullah University of Science and Technology, grants REP/1/3848-01-01, URF/1/4040-01-01 and base lines.

The aim of this study is to show the influence of temperature on the relative value of the short-circuit photocurrent density obtained from an n+-p-p+silicon solar cell front illuminated with modulated polychromatic light. The solar cell was already subjected to charged particules irradiation flux (Φp) and intensity (kl,) and remained under both magnetic field (B) and temperature (T). Thus, the graphical representation of the relative value of the short-circuit photocurrent density as a function of the square of the magnetic field (B) yields to determine the slope, which is related to the mobility of minority carriers in the base. It is obtained for a back surface field silicon solar cellunder both temperature and irradiation flux of charged particules.

An application of the so-called acid-base diode would be the sensitive detection of nonhydrogen cations in an acidic medium based on salt-effects. For diode purposes different connecting elements between the acidic and aqueous reservoirs of the diode were developed, namely a polyvinyl alcohol (PVA) hydrogel cylinder, and a polyvinyl butyral (PVB) membrane. During the measurement of the voltage – current characteristic (VCC) of the diode, it was found, that in the case of PVA gel cylinder an overshoot (a local maximum followed by a local minimum) appeared in the time vs. current curve, while the diode was switched between modes (open or closed), that is the direction of the applied voltage was reversed. The overshoot did not appear in PVB membrane.The existence of overshoots was studied by numerical simulations. The time response of the diode with different hypothetic connecting elements was investigated, when the diode was switched between modes via changing the polarity of applied voltage. We found that larger diffusion coefficients of hydrogen and hydroxide ions explain the appearance of overshoots. By examining the concentration and potential profiles a qualitative explanation of this phenomenon was given.

Bone grinding is used to remove the skull bone and access tumors through the nasal passage during cranial base neurosurgery. The generated heat of the spherical diamond tool propagates and could damage the nerves or coagulate the arteries blood. Little is known about the non-Fourier behavior of heat propagation during bone grinding. Therefore, this study develops an analytical model of the hyperbolic Pennes bioheat transfer equation (HPBTE) to calculate the three-dimensional temperature and necrosis in the grinding region. In vitro experimental investigations were carried out, and the contact zone temperature was measured using an infrared thermography system to validate the proposed thermal model. The results demonstrate that the HPBTE provides more reliable temperature evaluation and thermal damage than Fourier or parabolic heat transfer equation (PHTE). Due to the low thermal diffusivity of the bone, the lower grinding feed rate leads to higher temperature amplitude and a smaller radius of the affected zone in the surface and depth of the bone. Also, the intensity of bone necrosis decreases with the increase of the feed rate, and the shape of the damage zone becomes stretched. This analytical model can assess the potential risk of the surgery before clinical trials. Also, it could be used for comparing the different operating conditions to minimize bone necrosis and improve the control process in neurosurgeries.

Two new homologous series of Schiff’s base derivatives with lateral methyl substitution having central cinnamates VIn and benzoates VIIn moiety were prepared. All the compounds were characterised w...

Purpose Using typical structure of asphalt pavement in Harbin area of China, and the formula of generalized friction coefficient between base and surface layers of asphalt pavement in cold area is established. Design/methodology/approach Through structural characteristics analysis of asphalt pavement in cold area, the generalized formula of friction coefficient between base and surface layers of asphalt pavement in cold area is derived. The formula can quickly calculate the friction coefficient between layers of asphalt pavement. Findings Based on quantitative analysis to the contacting state between layers of asphalt pavement in cold area, the relationships between generalized friction coefficient and resilient modulus of asphalt mixtures, temperature shrinkage coefficient and temperature have been established. Originality/value The findings can enrich the description methods about the contacting state between layers of asphalt pavement, and have a certain theoretical and practical value. Through the application of the formula of generalized friction coefficient between layers, it can provide a technical basis for the asphalt pavement design, construction and maintenance in cold area.

A meso-analysis method which is derived from the base force element method (BFEM) was proposed for recycled aggregate concrete (RAC). A simple algorithm was used to generate the convex recycled concrete aggregate (RCA) model. Uniaxial compression numerical simulations were carried out on the numerical specimens with different replacement rates of RCA. The model predictions were in a good agreement with the test results. The proposed method is very promising. It can totally predict the full stress-strain curve of RAC, as well as the failure process and failure mode, including strain softening and strain localization.

Co base superalloys strengthened by coherent L12 ordered γ′ precipitate in a disordered face-centered cubic γ matrix represent a new opportunity for high-temperature alloy development. The emergence of alloys with low density and high specific yield strength at elevated temperatures has further energized the research and development efforts in the last 5 years. Initially stabilized by the addition of small amounts of Nb and Ta, these new generations of alloys with multiple alloying additions to form basic quaternary and ternary alloys have steadily expanded the property envelopes to raise hope for a modern class of superalloys with higher-temperature capabilities. This article reviews the work of a vibrant set of researchers across the globe whose findings are constantly unlocking the potential of these alloys. These developments have achieved high-temperature strength (at 870°C) >0.6 GPa, γ′ solvus temperature exceeding 1,100°C, and densities between 7.8 and 8.6 g/cm3.

Fabricating resin bases has become an easy and economical method to achieve the customization of brackets. This study aimed to assess the effect of the resin base on bonding strength of spherical self-ligating brackets. A defined amount of adhesive was bonded to the bracket base and constituted the new resin base. The thickness of the adhesive was measured and controlled at 0.5, 1.0, 1.5 and 2.0 mm, and a group without a resin base was used as a control. Sixty extracted human premolars were randomly divided into five groups. The brackets in each group were bonded to the specimen, and debonding tests were conducted. The shear bond strength (SBS) was calculated according to the measured debonding force in relation to the base area. The adhesive remnant index (ARI) score and the residual location of the fractured resin base were recorded. Enamel damage was also analyzed by scanning electron microscopy. After assessing for data normality and homogeneity, statistical comparisons between the groups and correlations among parameters were determined. P

SUMMARY Seismic shear wave velocity (S-velocity) shows a decrease towards the base of ice sheets in Antarctica and Greenland that is not accompanied by a corresponding decrease in compressional velocity (P-velocity). This decrease has been interpreted as arising from liquid water below the melting point (pre-melt water) at grain boundaries, but the lack of a corresponding decrease in P-velocity has not been explained. Representing grain boundaries as displacement discontinuities allows the change in P- and S-velocities to be written as functions of the normal and shear compliance of the grain boundaries. This allows the normal-to-shear compliance ratio of the grain boundaries to be constrained, and seismic anisotropy resulting from a partial orientation of grain boundaries to be estimated. This approach demonstrates that the observed reduction in S-velocity with no significant decrease in P-velocity near the base of ice sheets in Antarctica and Greenland can be explained by pre-melt water at small aperture grain boundaries. Such water may enable sliding along the grain boundaries and so may enhance creep of ice near the base of ice sheets. If stress state is anisotropic the aperture of water-containing grain boundaries may vary with azimuth, with the most open grain boundaries oriented with strikes perpendicular to least compressive stress. Microcracks and fractures may be treated also as displacement discontinuities and, together with oriented grain boundaries, may contribute to shear wave splitting as observed in West Antarctica in a fast-moving ice stream.

High thermal conductivity of carbon nanotube nanofluids (knf) has received great attention. However, the current researches are limited by experimental conditions and lack a comprehensive understanding of knf variation law. In view of proposition of data-driven methods in recent years, using experimental data to drive prediction is an effective way to obtain knf, which could clarify variation law of knf and thus greatly save experimental and time costs. This work proposed a neural regression model for predicting knf. It took into account four influencing factors, including carbon nanotube diameter, volume fraction, temperature and base fluid thermal conductivity (kf). Where, four conventional fluids with kf, including R113, water, ethylene glycol and ethylene glycol-water mixed liquid were considered as base fluid considers. By training this model, it can predict knf with different factors. Also, change law of four influencing factors considered on the knf enhancement has discussed and the correlation between different influencing factors and knf enhancement is presented. Finally, compared with nine common machine learning methods, the proposed neural regression model shown the highest accuracy among these.

The microstructure evolution in Re–Ru containing high generation Ni-base single crystal superalloy has been investigated during long-term isothermal exposure at 1000°C. The chemical and physical ch...

In this article, transient response of triangular longitudinal fin with internal heat generation under step change in (i) base temperature and (ii) base heat flux assuming is reported. The convecti...

The purpose of the study is to increase the completeness and reliability of approaches to determining the components of the cornering resistance a tracked vehicle, as well as to create a method for their assessment, which will be suitable for practical calculations. The article analyzes two components of the moment of cornering resistance of the tracked vehicle, which can be distinguished if we consider the interaction of the caterpillar with the support base through separate contact spots (active sections of the tracks located under the road wheels). The first component arises from the linear movement of the active sections of the tracks. The second is caused by the rotational movement of the contact patch about the vertical axis. The paper presents a mathematical model of the interaction of the propeller and a dense support base, which makes it possible to study the dependence of the components of the moment of cornering resistance on the geometric parameters of the undercarriage of a tracked vehicle. The horizontal reaction force in this case is presented as a function of the slip coefficient. The possibility of realizing various adhesion qualities of the propulsion unit in the longitudinal and transverse directions of sliding is provided. The model assumes a preliminary division of the contact patch into a finite number of elementary areas. Since the number of elementary sites affects the result, the article conducted a study to determine the minimum number of sites to ensure acceptable accuracy. An analysis of the expressions available in the literature was carried out to determine the specified component of the cornering resistance. The new empirical relationships that better agree with the mathematical model were proposed. The study of several existing tracked vehicles, differing in the mass and size of the track support surface, made it possible to conclude that it is advisable to take into account the moment of cornering resistance of the contact patch for various types of tracked vehicles.

The aim of the work is to develop algorithms and a set of programs for studying the dynamic characteristics of viscoelastic thin plates on a deformable base on which it is installed with several dynamic dampers. The theory of thin plates is used to obtain the equation of motion for the plate. The relationship between the efforts and the stirred plate obeys in the hereditary Boltzmann Voltaire integral. With this, a system of integro-differential equations is obtained which is solved by the method of complex amplitudes. As a result, a transcendental algebraic equation was obtained to determine the resonance frequencies, which is solved numerically by the Muller method. To determine the displacement of the point of the plate with periodic oscillations of the base of the plate, a linear inhomogeneous algebraic equation was obtained, which is solved by the Gauss method. The amplitude - frequency response of the midpoint of the plate is constructed with and without regard to the viscosity of the deformed element. The dependence of the stiffness of a deformed element on the frequency of external action is obtained to ensure optimal damping of vibrational vibrations of the plate.

This study compared the microleakages and compressive strengths of various base materials.To evaluate microleakages, 50 extracted permanent premolars were prepared. The teeth divided into 5 groups of 10 each according to the base materials. Cavities with a 5.0 mm width, 3.0 mm length, and 3.0 mm depth were formed on the buccal surfaces of the teeth. After filling the cavities with different base materials, a composite resin was used for final restoration. Each specimen was immersed in 2% methylene blue solution and then observed under a stereoscopic microscope (× 30). To evaluate the compressive strength, 5 cylindrical specimens were prepared for each base material. A universal testing machine was used to measure the compressive strength.The microleakage was highest in the Riva light cureTM group and lowest in the BiodentineTM and Well-RootTM PT groups. For the compressive strengths, in all groups, acceptable strength values for base materials were found. The highest compressive strength was observed in the Fuji II LCTM group and the lowest strength in the Well-RootTM PT group.