bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance of a wind turbine blade in sandstorms using a CFD-BEM based neural network
Authors: Zidane Iham F. , Swadener Greg , Ma Xianghong , Shehadeh Mohamed F. , Salem Mahmoud H. , Saqr Khalid M.
Published: October 2020

In arid regions, such as the North African desert, sandstorms impose considerable restrictions on horizontal axis wind turbines (HAWTs), which have not been thoroughly investigated. This paper examines the effects of debris flow on the power generation of the HAWT. Computational Fluid Dynamics (CFD) models were established and validated to provide novel insight into the effects of debris on the aerodynamic characteristics of NACA 63415. To account for the change in the chord length and Reynolds number along the span of the blade and the 3D flow patterns, the power curves for a wind turbine were obtained using the Blade Element Momentum (BEM) method. We present a novel coupled application of the neural network, CFD, and BEM to investigate the erosion rates of the blade due to different sandstorm conditions. The proposed model can be scaled and developed to assist in monitoring and prediction of HAWT blade conditions. This work shows that HAWT performance can be significantly diminished due to the aerodynamic losses under sandstorm conditions. The power generated under debris flow conditions can decrease from 10 to 30% compared to clean conditions.
Optical second harmonic generation from silicon (100) crystals with process tailored surface and embedded silver nanostructures for silicon nonlinear nanophotonics
Authors: Bhowmik Gourav , An Yong Q. , Schujman Sandra , Diebold Alain C. , Huang Mengbing
Published: October 2020

The development of on-chip nonlinear optical devices in silicon is of great importance to silicon photonics and silicon chip based quantum information processing technologies. With the aim for a viable solution to overcome the lack of second harmonic generation (SHG) in Si, which is fundamentally limited by its centrosymmetric lattice structure, our work investigates SHG behaviors from Si (100) crystals with silver nanostructures formed following deposition of an ultrathin silver film and subsequent annealing. This study is aided by additional techniques, including x-ray photoelectron spectroscopy for measuring surface band bending, secondary electron microscopy for monitoring surface morphology, and Raman scattering for assessing crystal stress. The resultant Ag nanostructures are found to strongly impact the second order nonlinear polarizations in the Si surface regions rather than the bulk. The SHG intensities are increased following the Ag deposition but reduced below the Si control levels after annealing at 600 and 700 °C, which may be due to charge transfer from Ag to SiO2/Si and/or passivation of interfacial defects. Interestingly, annealing at higher temperatures (800 and 900 °C) leads to the formation of Ag nano-shell structures embedded below the SiO2/Si interface, different from the as-deposited and low-temperature annealing cases with Ag nano-spheroid structures appearing on the surface, and concomitantly, the SHG intensities are recovered and even exceed the level for the as-deposited sample in the p-Si case. The enhanced SHG following high-temperature annealing, particularly at 800 °C, is attributed to a redshift of the localized plasmon resonance of these embedded Ag nano-shells relative to the surface-covered nano-spheroids that leads to localized surface plasmon resonance around the fundamental light wavelength. Other factors including electric-field-induced SHG and the effects of stress or oxide thickness can be ruled out. This work suggests a novel approach to enhance second-order optical nonlinearity in Si through the formation of embedded metal nanostructures.
Rotational manipulation of a microscopic object inside a microfluidic channel
Authors: Harada Hiroyuki , Kaneko Makoto , Ito Hiroaki
Published: October 2020

Observations and analyses of a microscopic object are essential processes in various fields such as chemical engineering and life science. Microfluidic techniques with various functions and extensions have often been used for such purposes to investigate the mechanical properties of microscopic objects such as biological cells. One of such extensions proposed in this context is a real-time visual feedback manipulation system, which is composed of a high-speed camera and a piezoelectric actuator with a single-line microfluidic channel. Although the on-chip manipulation system enables us to control the 1 degree-of-freedom position of a target object by the real-time pressure control, it has suffered from unintended changes in the object orientation, which is out of control in the previous system. In this study, we propose and demonstrate a novel shear-flow-based mechanism for the control of the orientation of a target object in addition to the position control in a microchannel to overcome the problem of the unintended rotation. We designed a tributary channel using a three-dimensional hydrodynamic simulation with boundary conditions appropriate for the particle manipulation to apply shear stress to the target particle placed at the junction and succeeded in rotating the particle at an angular velocity of 0.2 rad/s even under the position control in the experiment. The proposed mechanism would be applied to feedback controls of a target object in a microchannel to be in a desired orientation and at a desired position, which could be a universally useful function for various microfluidic platforms.
Exploration of lattice Hamiltonians for functional and structural discovery via Gaussian process-based exploration–exploitation
Authors: Kalinin Sergei V. , Valleti Mani , Vasudevan Rama K. , Ziatdinov Maxim
Published: October 2020

Statistical physics models ranging from simple lattice to complex quantum Hamiltonians are one of the mainstays of modern physics that have allowed both decades of scientific discovery and provided a universal framework to understand a broad range of phenomena from alloying to frustrated and phase separated materials to quantum systems. Traditionally, exploration of the phase diagrams corresponding to multidimensional parameter spaces of Hamiltonians was performed using a combination of basic physical principles, analytical approximations, and extensive numerical modeling. However, exploration of complex multidimensional parameter spaces is subject to the classic dimensionality problem, and the behaviors of interest concentrated on low dimensional manifolds remain undiscovered. Here, we demonstrate that a combination of exploration and exploration–exploitation with Gaussian process modeling and Bayesian optimization allows effective exploration of the parameter space for lattice Hamiltonians and effectively maps the regions at which specific macroscopic functionalities or local structures are maximized. We argue that this approach is general and can be further extended well beyond the lattice Hamiltonians to effectively explore the parameter space of more complex off-lattice and dynamic models.
Generation of spin-adapted and spin-complete substitution operators for (high spin) open-shell coupled cluster of arbitrary order
Authors: Herrmann Nils , Hanrath Michael
Published: October 2020

A rigorous generation of spin-adapted (spin-free) substitution operators for high spin (S = Sz) references of an arbitrary substitution order and spin quantum number S is presented. The generated operators lead to linearly independent but non-orthogonal configuration state functions (CSFs) when applied to the reference and span the complete spin space. To incorporate spin completeness, spectating substitutions (e.g., Êivva) are introduced. The presented procedure utilizes Löwdin’s projection operator method of spin eigenfunction generation to ensure spin completeness. The generated operators are explicitly checked for (i) their linear independence and (ii) their spin completeness for up to tenfold substitutions and up to a multiplicity of 2S + 1 = 11. A proof of concept implementation utilizing the generated operators in a coupled cluster (CC) calculation was successfully applied to the high spin states of the boron atom. The results show pure spin states and small effects on the correlation energy compared to spin orbital CC. A comparison to spin-adapted but spin-incomplete CC shows a significant spin-incompleteness error.
Models and corrections: Range separation for electronic interaction—Lessons from density functional theory
Authors: Savin Andreas
Published: October 2020

Model Hamiltonians with long-range interaction yield energies are corrected taking into account the universal behavior of the electron–electron interaction at a short range. Although the intention of this paper is to explore the foundations of using density functionals combined with range separation, the approximations presented can be used without them, as illustrated by a calculation on harmonium. In the regime, when the model system approaches the Coulomb system, they allow the calculation of ground states, excited states, and properties, without making use of the Hohenberg–Kohn theorem. Asymptotically, the technique is improvable and allows for error estimates that can validate the results. Some considerations for correcting the errors of finite basis sets in this spirit are also presented. Being related to the present understanding of density functional approximations, the results are comparable to those obtained with the latter, as long as these are accurate.
Synthesis and reactivity of 3-(1-alkynyl)chromones
Authors: Sosnovskikh Vyacheslav Ya.
Published: October 2020

For the first time, the literature data on the methods of synthesis and reactivity of 3-(1-alkynyl)chromones are summarized and systematized. The main method for obtaining these compounds is the Sonogashira cross-coupling reaction of 3-halochromones with terminal acetylenes, and their most important chemical properties include the transformation into furans, reactions with dinucleophiles, ambiphilic [4+2]- and [4+3]-cyclizations, and also dimerization and mixed condensation of 2-methyl-3-(1-alkynyl)chromones due to the vinylogous methyl group. Except for the oxacyclization to furans, chemical transformations of 3-(1-alkynyl)chromones are accompanied by pyrone ring transformation, in which not only the carbonyl group but also the triple bond can participate. This significantly increases the synthetic value of these compounds and ensures the production of more complex heterocyclic systems based on them. The mechanisms of the reactions are discussed, the conditions for their implementation and the yields of the resulting products are indicated.

The bibliography includes 80 references.
Synthesis and Structures of 1,1′,2-Tribromoferrocene, 1,1′,2,2′-Tetrabromoferrocene, 1,1′,2,2′-Tetrabromoruthenocene: Expanding the Range of Precursors for the Metallocene Chemist’s Toolkit
Authors: Butler Ian R. , Beaumont Michael , Bruce Michael I. , Zaitseva Natalia N. , Iggo Jonathan A. , Robertson Craig , Horton Peter N. , Coles Simon J.
Published: October 2020

The synthesis, characterisation, and isolation of 1,1′,2-tribromoferrocene and 1,1′,2,2′-tetrabromoferrocene, which are key synthons in ferrocene chemistry, are described. These compounds are prepared using α-halide assisted lithiation. The crystal structures of 1,1′,2-tribromoferrocene, 1,1′,2,2′-tetrabromoferrocene, 1,1′-dibromoruthenocene, and 1,1′,2,2′-tetrabromoruthenocene have been determined and are reported together with a brief discussion of the intramolecular forces involved in the crystal structures.
Elevated blood urea nitrogen alters the transcriptome of equine embryos
Authors: Boakari Yatta Linhares , El-Sheikh Ali Hossam , Dini Pouya , Loux Shavahn , Fernandes Claudia Barbosa , Scoggin Kirsten , Esteller-Vico Alejandro , Lawrence Laurie , Ball Barry
Published: October 2020

High blood urea nitrogen (BUN) in cows and ewes has a negative effect on embryo development; however, no comparable studies have been published in mares. The aims of the present study were to evaluate the effects of high BUN on blastocoele fluid, systemic progesterone and Day 14 equine embryos. When a follicle with a mean (±s.e.m.) diameter of 25±3mm was detected, mares were administered urea (0.4g kg−1) with sweet feed and molasses (n=9) or sweet feed and molasses alone (control; n=10). Blood samples were collected every other day. Mares were subjected to AI and the day ovulation was detected was designated as Day 0. Embryos were collected on Day 14 (urea-treated, n=5 embryos; control, n=7 embryos). There was an increase in systemic BUN in the urea-treated group compared with control (P<0.05), with no difference in progesterone concentrations. There were no differences between the two groups in embryo recovery or embryo size. Urea concentrations in the blastocoele fluid tended to be higher in the urea-treated mares, with a strong correlation with plasma BUN. However, there was no difference in the osmolality or pH of the blastocoele fluid between the two groups. Differentially expressed genes in Day 14 embryos from urea-treated mares analysed by RNA sequencing were involved in neurological development, urea transport, vascular remodelling and adhesion. In conclusion, oral urea treatment in mares increased BUN and induced transcriptome changes in Day 14 equine embryos of genes important in normal embryo development.
A quantitative criterion for predicting solid-state disordering during high strain rate deformation
Authors: Becker Michael F , Kovar Desiderio
Published: October 2020

A quantitative criterion for predicting the onset of disordering during high strain rate deformation is defined that is based on the potential energy (PE) per atom (PE/atom). The criterion is a necessary, but not sufficient condition to predict disorder. The stress state and loading direction of the crystal must allow deviatoric displacements that can induce disordering and the strain rate must be sufficiently high. The criterion is tested using molecular dynamics (MD) simulations for Ag over a range of a stress states and loading directions relative to the crystal axis. It is found that, above a minimum PE per atom of −2.70 ± 0.01 eV/atom, the crystal becomes unstable and disorders at temperatures well below the equilibrium melting temperature. This criterion is found to be independent of stress state and loading direction, and results suggest that it can be applied broadly to other material systems and to scenarios where deformation is non-uniform and time dependent. An example is given for its application to Au in shear. We show that the minimum critical PE for disordering under high strain rate loading is estimated by finding the equilibrium PE per atom at melting, which can be obtained from a single MD simulation for each material. An example is provided that illustrates how PE/atom can be used to predict where a simulated system is with respect to the disordering threshold without conducting multiple simulations.
Detection of solid contaminants in gas flows using microwave resonant probes
Authors: Akhter Zubair , Taha Wesam , Rahman Mohammed Saif Ur , Abou-Khousa Mohamed A
Published: October 2020

The presence of undesirable solid contaminants can have adverse effects on the integrity of gas pipelines. One of the most common contaminants in such pipelines is black powder. Developing predictive maintenance protocols, including online quality monitoring, is imperative to ensure the on-spec supply of gas to customers and to avoid severe consequences such as pipeline blockage. In this paper, a microwave sensing system that utilizes resonant probes for the detection and monitoring of solid contaminants, is presented. The proposed probe is essentially a conventional circular waveguide with a resonant iris structure attached to the aperture. The concentration of solid contaminants in gas flows is assessed by analyzing the scattering parameters of transmitting/receiving probes at a resonant frequency, which are coupled non-intrusively to the pipeline. 3D electromagnetic simulations are performed for sensitivity analysis of the proposed sensing system. Furthermore, the detection and evaluation of solid contaminants are experimentally validated using air/sand flow in a 51 mm inner diameter pipeline. The efficacy of the proposed system is demonstrated following the successful detection of solid contaminants in the dual-phase flow. Additionally, it is also illustrated that inclusion of a resonating iris structure in the aperture of the circular waveguide results in enhanced sensitivity when compared to a non-resonant counterpart.
Numerical studies on the boundary entanglement in an optomechanical phonon laser system
Authors: Meng Qing-Xia , Deng Zhi-Jiao , Cui Shi-Wei
Published: October 2020

In our previous work (Meng et al 2020 Phys. Rev. A 101 023838), we discover the phenomenon that the quantum entanglement on the driving threshold line remains a constant in a three-mode optomechanical phonon laser system. In this paper, to find the conditions under which the constant boundary entanglement shows up, we explicitly study how this boundary entanglement depends on various parameters through numerical integrations. The results show that the necessary and sufficient condition is a resonant frequency match between the optical frequency difference and the mechanical vibrational frequency, and this constant value is proportional to the multiplication of the square of the optomechanical coupling strength and the resonant driving threshold power.
Utilizing of high-pressure high-temperature synthesis to enhance the thermoelectric properties of Zn0.98Al0.02O with excellent electrical properties*
Authors: Chen Qi , Li Xinjian , Wang Yao , Chang Lijie , Wang Jian , Zhang Yuewen , Ma Hongan , Jia Xiaopeng
Published: October 2020

The temperature in the high-pressure high-temperature (HPHT) synthesis is optimized to enhance the thermoelectric properties of high-density ZnO ceramic, Zn0.98Al0.02O. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy show that HPHT can be utilized to control the crystal structure and relative density of the material. High pressure can be utilized to change the energy band structure of the samples via changing the lattice constant of samples, which decreases the thermal conductivity due to the formation of a multi-scale hierarchical structure and defects. The electrical conductivity of the material reaches 6 × 104 S/m at 373 K, and all doped samples behave as n-type semiconductors. The highest power factor (6.42 μW ⋅ cm−1⋅K−2) and dimensionless figure of merit (zT = 0.09) are obtained when Zn0.98Al0.02O is produced at 973 K using HPHT, which is superior to previously reported power factors for similar materials at the same temperature. Hall measurements indicate a high carrier concentration, which is the reason for the enhanced electrical performance.
Comparative analysis of the parameters of generators with circular and asymmetric oscillations
Authors: Gerasimov M D , Lubimyi N S , Yakovlev E A
Published: October 2020

In the paper the calculation and comparative analysis of the technical characteristics and main parameters of a vibrator with circular oscillations with a driving force equal to 5 kN and a vibrating device with asymmetric oscillations with a similar driving force for two, three and four stages of vibration blocks with directional vibrations are performed based on the design methodology of vibration devices with asymmetric oscillations. The aim of this paper is to identify the positive and negative effects in the transfer of the vibrator with circular oscillations on the vibrating device with asymmetric oscillations. The paper uses a method for selecting rational ratios of static moments of debalances, which provides the highest coefficient of azimuth of the driving force of both individual stages of vibration blocks, and the coefficient of the total driving force of the entire device as a whole. This paper will be useful for manufacturers of vibration machines for construction and road vehicles.
Modeling of organizational and functional components of investment and construction controlling in the reproduction of eco-residential real estate
Authors: Krygina A M , Avilova I P , Oberemok M I , Grebenik A G
Published: October 2020

This article is devoted to the development of a structural and functional model for the formulation of high-performance regional business systems in the context of implementing eco-projects at various levels in a situation where supply exceeds demand. This approach generally corresponds to the current problems of macro and micro levels in the domestic and global economy and takes into account its negative impact on the construction industry. The theory is based on situational modeling with the identification of two key situations according to the principle of transformational development of local internal competition. The paper proposes zoning of a standardized life cycle of planning and controlling of the regional environmental programs. A structural and functional model of system formation of consortium-type organizational structures has been developed to regulate local and cluster competitiveness in construction on the meso-level. It suggests a principal situational economic model of functioning of mortgage and investment projects and programs for the development of competitiveness in territorial reproduction systems. It also provides the conceptual model of the life cycle of managing the cost of mortgage and investment programs and observes two periods of the life cycle of managing investment projects.
The dynamics of the stability of the functioning of ZAO Belgorodskij cement in 2016-2019
Authors: Slabinskaya I A , Benderskaya O B
Published: October 2020

Stability of functioning is one of the main goals of managing economic entities, whether they are independent business units or divisions of business associations. The complexity of this economic category determines the need to improve scientifically grounded instruments for measuring, assessing and monitoring the level of sustainable functioning. One such tool is the comparative comprehensive assessment (CA) of the stability of functioning, which is described in this article. The assessment author’s methodology is based on a system of 12 indicators of the stability of functioning. For a dynamic comparative assessment of enterprise, the author’s method of calculating a comprehensive assessment is used - a modified method of scoring. The object of the research is ZAO Belgorodskij cement, one of the largest enterprises in the building materials industry in the Belgorod region. The subject of the research is the dynamics of the stability of the functioning of ZAO Belgorodskij cement in the period 2016-2019. During this period, there was a constant struggle between the local authorities and the management of the enterprise for the closure of the plant, which the plant managers oppose. The objectives of the study are to improve the methodology for a comprehensive assessment of the stability of functioning and assess the impact of uncertainty in the position of the plant on the stability of its functioning.
Efficiency of using shungite filler for modifying organic binder
Authors: Yadykina V V , Vyrodova K S , Potapov E E
Published: October 2020

Modification of bitumen with various additives, including polymer ones, is one of the most effective ways to regulate the performance properties of asphalt concrete. Due to the high cost of polymers, a promising area of research is to reduce the polymer content, for example, by introducing mineral filler into its composition. A wide range of properties and unique structure of fullerene-containing natural shungite allow it to be used in various branches of science, industry and technology to create a variety of materials and determine the search for new areas of its application. One of the ideas that are currently under development is the use of shungite in conjunction with an organic binder used for the production of asphalt concrete. The work is devoted to the study of the influence of fine shungite on the characteristics of polymer-bituminous binder (PBB) and asphalt concrete. It is shown that the introduction of shungite into the PBB increases its viscosity, adhesive and cohesive properties, and the homogeneity of the mixture. This is due to the unique composition, structure and properties of shungite. The positive influence of the use of polymer shungite binder on the quality of asphalt concrete was established. With the introduction of 5% shungite in the PBB composition, the strength at 20 and 50°C, the strength of water-saturated samples, and the shear stability of polymer asphalt concrete significantly increased. This made it possible to reduce the polymer content of PBB by 10%.
The modern information technologies in construction for improving occupational safety
Authors: Klimova E V , Semeykin A Yu , Sinebok D A , Khomchenko Yu V
Published: October 2020

Today, construction takes first place in the number of industrial accidents, including severe and fatal ones. Inconsistency of jobs, work at height, work in extreme conditions, adverse weather factors, all this and much more is the cause of traumatic factors. The article discusses the implementation aspects of modern information technologies that allow you to assess the psycho-emotional state of the employee in real time and make timely decisions on the organization of work safety. Based on the results of the analysis, a “Psychophysiological Monitoring System” is proposed. Existing analogues of such systems are not used in production, more often they are designed to assess the physiological state of athletes. The technology of analysis and assessment of the state of workers is presented, which a complex of interrelated parts is such as: the main sensor module, local receiving and transmitting device, stationary receiving and processing device, sensors for evaluating external conditions, a database and a server for data transmitting and processing. Based on the developed hardware-software complex, measures are proposed for the prevention of injuries in construction during construction and installation works on height.
Lightweight materials based on wood waste
Authors: Yespayeva A S , Altayeva Z N , Sarsenbayev B K , Karshyga G O , Sauganova G R
Published: October 2020

This paper discusses ways of recycling woodworking waste into light aggregate, optimal compositions of modified binders, as well as the mechanism of cement hydration in the presence of dispersion polymer powders. The methods of obtaining light aggregate based on woodworking waste by granulating in a disc granulator, which is a plate with a tilt angle of 450 and a number of turnovers of 17-19 rpm, are considered. Methods for obtaining granulated aggregate using sawdust of various fractions by the roasting free method are presented, optimal granulation modes are determined, and the main characteristics of the resulting aggregate and concrete based on them are studied. The optimal composition of granulated aggregate on modified cement provides 40 … 60 % of wood processing waste, 60 … 40 % of cement, 25 … 32 % of water and granulation time - 7 … 9 minutes. With this composition, the bulk density of the resulting aggregate corresponds to 850…750 kg/m3, the maximum strength of the granules when compressed in the cylinder is 3.5…4.1 MPa. The optimal content of the polymer additive in the binder is in the range of: mowilith - 0.4…0.7 % and tylose - 0.21…0.13 %. Granulated aggregate on modified aggregate has a frost resistance in the range of F35… F50. The choice of granulated aggregate on modified cement showed the effectiveness of the aggregate for light concretes. The strength characteristics of modified concrete of 25-75 brands were studied. The mechanical properties of modified concrete depending on the average density were studied. Concrete with an average density of 1000 kg/m3 has M25 brand, at 1200 kg/m3 - M35, at 1300 kg/m3 - M50, at 1500 kg/m3 - M75.
Movement of particles of concrete mixture aggregate subjected to vibration by cylindrical punches
Authors: Kirilov I V , Khanin S I , Voronov V P
Published: October 2020

For compaction of the concrete mixture in the manufacture of reinforced concrete products using the formless production method on long stands, as a universal and widespread method, vibration is used. The aim of the study was to establish the regularities of the process of spreading a cylindrical punch of a continuous formless machine of vibration oscillations on the aggregate particles of a viscous concrete mixture in the form of crushed stone and sand. The chaotic movement of filler particles of various sizes with an arbitrary number of degrees of freedom, due to their large number, movement, and exchange of impulses, is considered. The problems of the development of mathematical descriptions of the motion of spherical filler particles of different grain size in the vibration of a cylindrical punch with a viscous environment and determination of their average values of travel speed and distance through random motion were solved, the average values for these parameters at vibration of the punch with frequencies and amplitudes that are applied in industrial conditions were found. In the course of the work, the method of mathematical modeling was used. The result of this work is to establish the possibility, for particles of different sizes, of varying the average values of the speed of movement and the path traversed in a viscous environment, carried out by changing the characteristics of the vibration of the punch. The regularities of changes in the parameters under consideration for filler particles of various sizes depending on the frequency and amplitude of vibration oscillations of the punch surface are considered.
Modeling the external business environments for the Vietnamese construction SMEs in a transition economy
Authors: Nguyen The-Quan , N Preece Christopher
Published: October 2020

Vietnam has been shifting from a centrally planned economy with subsidy schemes, to a socialist-oriented market economy with multiple economic components. The internal dynamics and external pressures have caused many changes in the environment for small and medium size construction enterprises. This research models the external environment in order to aid understanding of the strategic management of such contractors in the construction industry of Vietnam. Semi-structured interviews of senior managers were combined with a mailed questionnaire to collect data. Seven major concepts were found to emerge including the economic administration of the country, the legacy of the old system, changes in society, nature of the workforce and the variety of business styles found. The research results show that the behaviour of key stakeholders has a major impact on the strategic/competitive behaviour of the concerned firms and their profitability.
Effective risk management of transport facilities construction
Authors: Spiridonov E S , Logvinenko A A , Dukhov A A
Published: October 2020

From the point of view of the resource intensity of creating communication tools (investment, labor, materials, energy, time), the leading place in production belongs to transport, and in it – railways and highways. This study examines various aspects of the application of the risk management system in the management of transport construction. Methods of risk minimization depending on the type of risk are presented: the risk of legal error, the risk of the customer’s insolvency, the risk of a suboptimal loan portfolio, and the risk of non-fulfillment of financial indicators. A matrix form of comparison of identified risks is proposed for the development of the most effective methods of managing them. Using the example of the insolvency risk, which is one of the most characteristic for transport construction, the possibility of assessing the risk by a quantitative method is shown. The risk was quantified using the G. Markowitz model. To assess risks, it is proposed to use a coefficient method that allows determining the criteria that characterize their solvency based on an express assessment of the financial condition of customers, and justify recommendations for concluding contracts with them for the construction of a transport facility. The proposed matrix form of comparison of the identified risks allows formulating recommendations for reducing the impact of risks on the stability of the construction production process in a more reasonable way.
Improvement directions of technical regulations in the field of reinforced cellular concrete structures
Authors: Kladieva P V , Koshlich Yu A
Published: October 2020

Effective management of real estate complexes, which determines the rational capital intensity of ownership of buildings and structures, largely depends on the consumer qualities of building materials and products included in the investment and construction project at the design stage. The implementation of the principles of rational design, which are regulated in unique and technically complex and responsible structures, is still not properly reflected in the design of second-class objects of responsibility, which, however, make up more than 70% of the capital intensity of the construction market, mainly housing. Complex composite materials that combine innovative and energy-efficient components and technologies, as well as structures made from them that contain significant reserves of load-bearing capacity, which are opened and implemented by improving design standards and rational technical solutions, have the greatest potential for rationalization. Reinforced cellular concrete, which effectively combines load-bearing and enclosing functions, is one of the most popular construction technologies in the perspective practice of low-rise construction. Currently, however, the design of reinforced structures made of cellular concrete in Russia, abroad, mainly performed according to the normative documents, often not taking into account the significant differences in physical and mechanical properties, material structure, principles and working mechanisms of various types of concrete under load, as well as the uniqueness of plastic properties of cellular concrete when assigning the form and composition of discrete reinforcement. In this regard, there is a need to revise and systematize existing standards that contain requirements for the design of directly reinforced structures made of cellular concrete, generalize European experience and these standards, update information in them, as well as develop modern national standards in this area. In addition, the practice of designing bent cellular concrete structures has revealed a significant reserve for increasing the load-bearing capacity of these elements, associated with insufficient inclusion of the material of the traditionally used rod reinforcement due to the primary destruction of the contact layer (pulling the reinforcement). In order to increase the durability and reduce the resource intensity of national cellular concrete structures, the adopted methodology for their design needs to improve both the regulations that establish the principles and rules for calculating reinforcement elements of structures, and structural elements used in precast and in-situ practice of discrete reinforcement.
Improving the efficiency of the material grinding process
Authors: Romanovich A A , Amini Ebrahim , Romanovich M A
Published: October 2020

The paper provides an analysis of grinding systems used in the world practice, including the main technical solutions in the field of fine grinding of materials using a ball mill, and also presents indicators of their efficiency. It was found that the grinding systems of the partitioned grinding process with pre-grinding in a press-roll grinder showed the greatest efficiency from their use. However, today in various countries, free-standing units are used for deagglomeration of pressure-pressed semi-finished products, which require additional space for their placement and operation and maintenance costs. The authors describe the design of a press-roll unit with a device for breaking pressure-pressed materials, which allows reducing these costs, as it performs the following technological operations: volume-shear deformation of the material is carried out due to the conical profile of the main rolls; the compressed materials are disaggregated in the reverse direction of compression by means of additional rollers that have a reverse taper to the main rolls. A scientifically-based method for calculating the energy index of a new design of press roll unit is proposed, which allows for the energy calculation of these machines.
Use of wood processing industry waste for bitumen modification
Authors: Turobova M A , Danilov V E , Ayzenshtadt A M
Published: October 2020

The paper provides information about the method of obtaining a modifying additive to bitumen, including wood filler. The pore space of the filler contains a basalt reinforcing filler with an average particle size of 150-300 nm. Scots pine bark with an average particle size of 0.5-1 mm was used as a wood filler. The modifying additive was obtained by mixing fine basalt (30 % by weight) and wood bark. After careful mixing for 5 minutes, water was added, the mass of which is twice more than the calculated mass of the reinforced bark. Then the mixture was homogenized. The use of an additive for the preparation of a bituminous binder improves the thermal and physical characteristics of the organic binder (softening temperature and brittleness temperature). In comparison with other traditional stabilizing additives, the use of the proposed composition for the preparation of a bituminous binder also improves the thermal and physical characteristics of the organic binder, such as the brittleness temperature. A decrease in the brittleness temperature of the mixture indicates an increase in the frost resistance of the modified organic binder. For other characteristics, the modifying additive has a comparable effect on the properties of the binder with traditionally used materials.
Method of calculation and selection of design parameters and operational characteristics of the spiral expander
Authors: Sergeev S V , Nikulin I S , Saenko M Yu , Titenko A A
Published: October 2020

The paper proposes a method for calculating the main design parameters and operational characteristics of the HPEC using the Helmholtz equations of state. N-pentane, freon R11, and acetone were considered as the working fluid. The calculations were performed using the CoolProp 6.3.0 library. It was found that the most profitable for HPEC operating on the Rankin cycle with low-potential sources is n-pentane. LD expander operation and mass flow rate of the working fluid are calculated. The calculations were performed using the freely distributed open source library CoolProp 6.3.0. The calculations show that the most profitable WF for HPEC running on the Rankin cycle with low-potential sources is n-pentane. It is determined that the increase in costs when the temperature decreases before the SD is due to a decrease in the level of operation of the Lд expander, which in turn depends on the value of the steam enthalpy at the entrance to the ex-pander.
Determination of thermal conductivity of backfill
Authors: Churkin S V , Korshunov A A
Published: October 2020

Shallow foundations with thermal insulation can be used in the construction of low-rise buildings. Thermal insulation prevents freezing of soils under the foundation. The article presents the results of determining the thermal conductivity of sand with the addition of crushed brick and concrete rubble. The research was carried out in a specially designed unit, which consists of two climatic chambers connected to each other. The soil sample is maintained into the special cell. Heat flow and temperature sensors are placed in the soil sample. Before soil testing a numerical simulation of laboratory test was implemented in GeoStudio. Due to numerical modelling optimal dimensions of testing cell was defined. Results of laboratory testing of sand with a known thermal conductivity with using designed parameters of cell has a good agreement with calculated value. The test procedure was extended to soils with construction waste. The addition of 20% crushed brick to the sand reduces its thermal conductivity coefficient by 20.6% in the frozen state and by 10.1% in the thawed state. At the same time sand with concrete rubble showed a decrease in the thermal conductivity coefficient in the frozen state by 6.4% and an increase by 13.4% in thaw. The effect is occurred because of the addition of particles of different mineralogical composition with different thermal conductivity. The results of testing can be used in making forecast of the thermal regime of soil stratum when designing shallow foundations.
Improvement of the design of the aeration device of the pneumatic chamber pump
Authors: Lozovaya S Yu , Fadin Yu M , Gavrilenko A V , Gavrilenko Yu V
Published: October 2020

The production of building materials is a complex technological process involving the processing of raw materials with various physical and mechanical properties, as well as using a variety of degrees of complexity of technological equipment and auxiliary mechanisms. High-pressure pneumatic transport has found application in construction, refractory, chemical and other industries. It is widely used for transportation of fine-grained bulk materials such as cement, alumina, soda, apatite, ash, clay, synthetic products, mineral fertilizers. The process of pneumatic transportation occurs due to the action of compressed air on the material being moved. However, at the same time, as a rule, there are through channels in the material layer, which leads to an increased consumption of compressed air, part of the unloaded material remains at the bottom of the pump chamber, which reduces productivity. Due to the fact that some fluidizing devices can form through channels in the material layer and given the large volumes of material being transported, it is necessary to solve issues to improve the efficiency of pneumatic chamber pumps and reduce the consumption of compressed air required for transporting bulk materials. This can be achieved by organizing effective fluidization of the material, that is, uniform mixing of the transported material with air.
Method of designing robotic complexes with relative manipulation modules
Authors: Gaponenko E V , Anciferov S I , Kholoshevskaya L R , Kuzmina V S
Published: October 2020

The paper offers a method for designing robotic complexes with six degrees of freedom for processing complex parts containing a base and a module for installing tools and a module for processing parts placed on it, made in the form of parallel structure mechanisms, using CAD/CAM/CAE of the NX system under the control of the Teamcenter PLM system. Based on the terms of reference and draft documentation, a preliminary composition of the complex for components of the upper level of the assembly was developed. The stages of designing an electronic-digital model of a robotic complex are presented. A fully parameterized control structure was developed, which is the basis for building robotic complexes of various classes. The use of this approach allows the designer to reduce the complexity of designing similar complexes and simplify the process of making changes, as all changes are made to one part of the product, which has many versions. The application of the developed design methodology for various versions of robotic systems is shown. An algorithm for strength calculation of the assembly is presented. It is shown that the most effective result can be achieved only by using a combined design and calculation methodology.
Temperature modification of diatomite sludge of oil extraction production at obtaining a sorbent
Authors: Starostina I V , Makridina Yu L , Sapronova Zh A , Bomba I V
Published: October 2020

One of the most widely used methods of water treatment is adsorption. The use of agricultural waste is of great interest in obtaining economical and efficient sorption materials. In this paper, the features of temperature modification of diatomite sludge are studied. Diatomite sludge is a multi-tonnage waste of oil extraction production formed during the purification of sunflower oil with diatomite. The kinetics of thermal activation of diatomite sludge at temperatures of 450, 500, and 600 °C was studied. It was found that the temperature of 450 °C is optimal for thermal modification of waste. In this case, part of the organic compounds is preserved, as with a further increase in temperature, they completely disintegrate into gaseous products. IR spectra and energy dispersion analysis were analyzed, and the structure and physical and chemical properties of diatomite and diatomite sludge were studied before and after heat treatment. It was found that the water extract of the samples, both initial and thermomodified, has a pH close to neutral. With an increase in the firing temperature, a small suspension effect is observed, which means the presence of a charge in the DSH particles in the aqueous medium, which can intensify the convergence of molecules with a positive charge with the surface of the sorbent. The development of methods for the secondary use of agricultural raw material processing waste for wastewater treatment allows solving comprehensively the problems of reducing the anthropogenic load on natural ecosystems, is an urgent task of modern society for environmental protection, and has scientific and practical significance.
TiO2 coatings on the surface of buildings structural elements
Authors: Sirota V V , Zaitsev S V , Limarenko M V , Prochorenkov D S
Published: October 2020

The article presents the results of a study of the photocatalytic activity of coatings based on titanium dioxide on various structural elements of buildings. Fine-grained lightweight concrete, porcelain stoneware and window glass were used as a base. TiO2 coating was applied by reactive magnetron sputtering. The structure and phase composition of the coatings were investigated by scanning electron microscopy and X-ray phase analysis. The photocatalytic activity of the samples was evaluated according to ISO 27448: 2009 and ISO 10678: 2010. The photocatalytic efficiency of the obtained TiO2 coatings on building materials is shown. The data obtained allow us to make a preliminary assessment of the effectiveness of the application of this method of applying photocatalytic coatings to structural elements of buildings, which will be clarified in the course of future studies.
Synthesis and characterization of properties of zinc coated Thaumatococcus daniellii extracts for solid state application
Authors: Emetere M.E. , Ahiara Ikechukwu M.
Published: October 2020

Recent technological inventions focus on the eco-friendly device that would not constitute hazard to immediate environment i.e. both in the short and long term. This research focus on screening bio-semiconductor using synthesized zinc coated Thaumatococcus daniellii extract. The band gap of sample 1 (extract in methanol solution), sample 2 (extract in ethanol solution) and sample 3 (extract in butanol solution) was calculated as 2 eV, 1.67 eV and 2 eV respectively. Also, the low and high Q-transition energy in the ethanol and butanol solution was able to show that the d-shell (d10) of the zinc atom was modified. This modification is a huge possibility of deriving bio-semiconductor from plant extract.