bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electromechanical drive fault detection
Authors: Iureva R , Margun A , Maltseva N , Vedernikov K 
Published: November 2019

Abstract
The paper presents the simulation model for the process of electromechanical drive disorder detection which is used to evaluate the drive reliability. The low efficiency and inoperability of the drive could be partial or complete. A proper functional drive provides under certain conditions the maximum efficiency of its use. The ability of the partially operating object application in the same conditions is less than the maximum possible one, but its indicators could be still within limits established for the proper functioning, which is considered normal. A partially inoperable object could function, and at the same time, its level of efficiency is lower than the allowed one. An inoperable object couldn’t be used as it was intended, and the research presented in this paper shows how to enable providing the drive reliability evaluation and analyze its proper functioning.
Numerical simulation of heat transfer processes of the circuit breaker contact system
Authors: Murashov Iu , Frolov V , Kvashnin A 
Published: November 2019

Abstract
The article is devoted to the study of heat transfer processes of the high-current AC circuit breaker contact system. The creation of a mathematical model is based on the application of well-known physical laws such as the Joule-Lenz and Fourier laws, which describe physical processes in the form of partial differential equations. Cooper-Mikic-Yovanovich correlation is used for evaluation of thermal and electrical contact conductance. The developed mathematical model is verified by the results of experimental studies. The calculation of the composite material properties for numerical simulation of heat transfer processes is presented. The calculation is presented for the actual design and materials of the circuit breaker.
Criteria for ensuring acoustic safety in the assembly shops of machine-building enterprises
Authors: Kaverzneva T , Tarkhov D , Uljanov A , Senchenko V , Pshenichnaya C , Alibekova I 
Published: November 2019

Abstract
We consider the problem of providing acoustic safety at the machine-building enterprises, where manual pneumatic tools and electrical tools are widely used in assembly shops. As an example we considered the noise during operation of pneumatic tools, which are the most preferable from the point of view of ensuring electrical safety. The necessity of monitoring audiograms of operators performing assembly operations, repair and adjustment at the machine assembly lines is justified. We analyzed the types of the used pneumatic tools and their service life, measured the level of generated noise and compared the obtained data with the passport acoustic characteristics from manufacturer. As a result, we showed the need to take into account the operating characteristics of instrument while ensuring acoustic safety. The main criteria for acoustic safety are defined.
Human safety ensuring in power supply systems with dead-earthed and insulated neutral wire
Authors: Markelov V , Vostrov K 
Published: November 2019

Abstract
In the current paper, the human safety issues in different power supply systems are considered. The conditions for residual-current device utilization and protective characteristics in grounded-neutral and insulated-neutral power supply systems are reviewed. Also, the endangerment factors and accident statistics are analyzed. Based on the given data, the judgment on the safety of different power supply system is given and a novel approach in the residual-current device setting up is proposed. Finally, the topology for IT system performing from TNC system is shown.
Shaping of structural and mechanical properties of heavy duty mandrels used for seamless pipe rolling
Authors: Gevogian G A , Vorobyev R A , Pachurin G V , Filippov A A , Mukhina M V , Kutepova L I 
Published: November 2019

Abstract
The main spheres of high-strength seamless pipes application are oil and gas production sectors, as well as the defense industry. Therefore, increasing the piercing rolling efficiency, increasing the strength and durability of the tool are the main factors that ensure the smooth production of seamless pipes. The article justifies the choice of the steel grade and displays the developed manufacturing technological cycle of heavy duty mandrels used for piercing and helical rolling of seamless pipes.
Ventilation modes of operation and their representation at the power characteristics of turbine stages and compartments
Authors: Tatarinova Natalia , Suvorov Dmitry 
Published: November 2019

Abstract
The article proposes an analysis of the main approaches in the theory of ventilation processes applied to the correct determination of ventilation losses occurring in the stages and compartments of TPP steam turbines in operating modes with low volumetric flow rates in a low-pressure cylinder. The features of the flow of ventilation processes in the low-pressure flow parts of CHP steam turbines and methods of their study are presented. New physical and mathematical models for calculating the ventilation power losses in the flow part of the turbine are considered. The universal generalized mathematical dependence for a high-precision estimation of the ventilation power losses of the turbine compartments is substantiated, taking into account the whole variety of parameters determining the level of these losses. On its basis, the authors have created mathematical models for calculating several types of CHP steam turbines for rapid assessment and accounting of technical and economic indicators of turbine operation all the possible range of operating modes. The basis of the new calculation models is adequate power and flow rate characteristics of the turbine stages and compartments, so the computational results correlate well with the experimental data, allowing to analyze a wide range of operating modes.
The possibility of increasing the efficiency of condensers at the CHP
Authors: Stepanov Oleg , Antonova Elena , Rydalina Natalya , Zakharov Vladislav , Antipin Stepan 
Published: November 2019

Abstract
In traditional condensers of combined heat and power (CHP) plants, water is used, which is discharged into the environment and creates environmental stress. It is proposed to cool the steam by air or freon. The basic schemes of CHP condensers operating on compressed air and freon are given. A comparative calculation of the condenser operating on water, air and freon was carried out. Analysis of the results shows the effectiveness of air, and freon compared to water. The advantage of freon is that it circulates in the heat exchanger, forming a closed system. At decreasing the temperature difference at the inlet and outlet to the condenser, the heat transfer coefficient of freon is higher than that of air.
The influence of design parameters on the blade flutter boundaries
Authors: Abdukhakimov Farrukh , Vedeneev Vasily , Kolotnikov Mikhail , Makarov Pavel 
Published: November 2019

Abstract
Blade flutter is one of the major problems that designers of modern gas-turbine engines face. In this paper, a study of the influence of the design parameters on prediction of blade flutter in compressors of gas-turbine engines is presented. As a rule, the flutter of compressor blades is predicted using simplified criteria based on the experience of designing and refining engines. These empirical and probabilistic criteria are not applicable to evaluation of the flutter since the parameters in question are not among the decisive parameters for simplified criteria. In this work, the energy method is used. It is shown that the inter-blade tension value has a significant influence on the blade flutter prediction, while the effect of other design parameters under investigation on the blade flutter prediction is insignificant.
To investigation of performance of the gas turbine plant, which operates with the working medium humidification in the inlet and overexpansion in the outlet
Authors: Osipov B M , Kh Perelshtein B , Zunino P , Derevianko O 
Published: November 2019

Abstract
The possibilities of increasing the specific power and efficiency of the gas turbine plant are considered by the working medium overexpansion behind the power turbine and the water injection into the engine inlet. The paper demonstrates that such a means can be used not only for a newly designed GTP, but also implemented in already operating power plants.
Mathematical modeling of operation processes of refrigerant compressor self-acting valves of domestic refrigerators
Authors: Petrosov S P , Kozhemyachenko A V , Alekhin S N 
Published: November 2019

Abstract
The article presents a mathematical model of refrigerant compressor self-acting valves for domestic refrigerators providing a set of data characterizing compressor operating cycle: change in the cylinder pressure, change in cylinder volume, and change in gas flow entering or leaving the cylinder, change in moving trajectory of the valve plate. The technique and algorithm for calculating valves parameters in the compressor operating cycle is proposed. The presented mathematical model provides valves calculation and ensures calculation analysis of the valves depending on their parameters for a particular model of a refrigerant compressor.
Experimental validation of a compact mixed-flow compressor for an active high-lift system
Authors: Kauth Felix , Maroldt Niklas , Seume Joerg R 
Published: November 2019

Abstract
Compact, electrically-driven compressors are a core component of a novel active high-lift system for future commercial aircraft. A newly-developed aeromechanical optimization process was used to design the compressor stage. The optimization resulted in an unusual mixed-flow compressor design with very low aspect ratio blades and a high rotational speed of up to 60,000 rpm. Due to the unusual design, experimental validation of the performance predictions by means of CFD is necessary. This paper presents the first experimental results obtained using a preliminary prototype at part-speed, i.e. rotational speeds from 20,000 to 30,000 rpm. The experimentally-determined pressure ratios deviate up to 1.5 %, the polytropic efficiencies up to 4 percentage points from the CFD predictions. Besides the deficiencies of available turbulence models, the underestimation of overall losses is presumably due to the omission of the volute in the CFD model. An experimental validation of the CFD predictions at full-speed is under way.
Prospects of binary energy generation systems based on the joint use of traditional sources of energy and wave motion energy
Authors: Yu Shabalov M , Filatova I I , Kuskova Y V 
Published: November 2019

Abstract
Electricity consumption of offshore oil and gas drilling platforms is usually provided by gas generator installations. However, such installations are expensive in operation and emit significant amounts of carbon dioxide and nitrogen oxides. Electricity consumption from the main grid is the best option, but expensive for platforms located far from the coast and with limited environmental benefits, if not supported by environmentally friendly production. Offshore wave energy technology, which is currently being developed for deep-water areas, can be connected directly to the platforms and work in parallel with gas turbines. Wave power station will save fuel and reduce carbon dioxide emissions, while there is no need for a long and expensive connection to the coastal grids. Operational strategies and fuel savings and emissions, depending on the size of the wind farm, are quantified by the example of the offshore oil and gas platform in the Far East shelf. In this paper, an assessment is made of the prospects of using the approach of dual power generation systems, which in turn will provide a significant reduction in fuel consumption and emissions, especially if we consider starting and stopping gas turbines. The main task is to find the optimal work strategy that balances the number of starts and stops of gas turbines with dissipative energy and fuel economy.
Theoretical study of gas parameters influence on reciprocating compressor performance intended for NGV-refueling compressor station
Authors: Kotlov A A , Kuznetsov L G 
Published: November 2019

Abstract
Ensuring the reliable and efficient operation of the reciprocating compressors in the wide range of the operating parameters is one of the important issues at designing, manufacturing and operating the compressor equipment. The quality of any equipment is determined by the improvement of calculating methods used at its designing. While designing the reciprocating compressors with a high compression degree the issue arises of determining the actual properties of the medium being compressed. The theoretical investigation of the gas initial parameters influence on the reciprocating compressor operation process is represented in this study. The results of the comparison of the reciprocating compressor operation for compression of ideal and actual gas are given in this study.
Comparative evaluation of renewable energy scenario in Ghana
Authors: Agyekum E B , Velkin V I , Hossain I 
Published: November 2019

Abstract
Availability of cheap, reliable and safe energy is very essential to the growth and development of every nation. This paper assesses solar radiation and wind speed at one site each in the southern, middle-belt and northern part of Ghana to estimate the potential of integrating solar and wind energy into the country’s energy mix. The analysis included the financial viability of a possible 2.5 MW installed solar power plant in Gomoa, Kintampo and Navrongo. The RETScreen software was used for the feasibility and financial viability evaluation. The study found out that the southern part of the country experiences the least solar irradiation as it recorded 4.73 kWh/m2/day, the middle belt recorded 5.28 kWh/m2/day, the northern belt however recorded the highest level of solar irradiation of 6.07 kWh/m2/day. It was also found out from the research that the southern belt has the highest annual average wind speed of 2.8 m/s followed by the northern sector with 2.3 m/s and the least was recorded in the middle-belt with an average wind speed of 2.2 m/s. The financial indicators like the internal rate return, equity payback years, cumulative cash flows and simple profitability index all indicated that the northern sector is the best site for the development of solar energy although the other parts of the country are also positive. The impact of the development of these plants will also have a considerable impact on the environment since the research shows some 93% reduction in the emission of greenhouse gases (GHG).
Development of the schematic thermal circuit of the heat power complex for highly effective use of secondary and renewable energy resources
Authors: Dyakonov Evgeniy , Papin Vladimir , Bezuglov Roman , Denisova Irina , Yanuchok Alexander , Dobrydnev Denis 
Published: November 2019

Abstract
Development process of a schematic thermal circuit of a heat power complex for highly effective use of secondary and renewable energy resources is considered in this article. Earlier authors developed basic elements of the developed scheme they are warmth transformation block (cascade thermal pump) and warmth accumulation block (accumulators of warmth and cold). The schematic thermal circuit of a heat power complex also contains additional units. It is the module of additional low-potential sources of warmth and cold connection, solar collector, the soil probe (heat exchanger), consumers of heat energy for a heat power complex. Authors defined receivers they are heating, hot water supply, conditioning, freezing and sources of energy are low-potential energy soil/air, solar energy, recuperation of ventilating air, utilization of warmth when conditioning rooms, using a sewer source.
Electrochemical sensor based on polyamide 6/polypyrrole electrospun nanofibers coated with reduced graphene oxide for malathion pesticide detection
Authors: Migliorini Fernanda L , Sanfelice Rafaela C , Mercante Luiza A , Facure Murilo H M , Correa Daniel S 
Published: November 2019

Abstract
An electrochemical sensor based on polymeric electrospun nanofibers of polyamide 6 (PA6)/polypyrrole (PPy) surface-modified with two forms of graphene was developed for the detection of malathion, an organophosphorus pesticide. The materials were chosen considering the electrospun nanofibers possess large surface area and porosity, while reduced graphene oxide has remarkable electrical conductivity, which is a good strategy to increase sensor sensitivity and improve the limit of detection towards the pesticide. The surface modification of nanofibers with graphene was carried out using chemically (CRGO) and electrochemically reduced graphene oxide (ERGO), in order to demonstrate how the degree of reduction of graphene oxide can influence its electrical conductivity. The influence of the reduction on the conductivity properties of graphene-based films was studied through electrochemical techniques: cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The platform modified with CRGO, which presented higher electrical conductivity compared to ERGO, was used in the electrochemical detection of the pesticide malathion and exhibited a low detection limit of 0.8 ng ml−1 (S/N = 3). The results indicate that chemically reduced graphene oxide is a potential alternative for modifying electrodes surfaces designed for sensing distinct pollutants of environmental or agricultural interest.
A mechanistic assessment of the potential ecological risk to seagrass meadows posed by marine echosounders
Authors: Alvarez A 
Published: November 2019

Abstract
Motivated by experimental evidence, a mechanistic model is used to investigate the impact of marine echosounder transmissions on seagrass leaves. The interaction of the ultrasonic field with the seagrass is solved within the leaf cross-section. The leaf tissue is assumed to be elastic, homogeneous and isotropic, with embedded cavities representing lacunae. A standard Galerkin finite element method is employed to numerically solve the resulting equations. Natural vibration frequencies are computed for leaves of Halodule wrightii and Syringodium filiforme. Strong perturbations in the leaf structure are expected when natural and echosounder frequencies match. The results reveal that a significant number of natural frequencies are within or near the typical frequency bands of echosounder operations. In addition, stresses in the leaf tissues of seagrass at 20 m depth were computed in a typical scenario for echosounder operations. Leaf-tissue damage in S. filiforme could result under these conditions. Within the framework of the theoretical assumptions, the results highlight the potential and, until now, unnoticed risks to seagrass meadows posed by marine echosounders.
Potential increase in oil and gas well leakage due to earthquakes
Authors: Kang Mary , Dong Yuhan , Liu Yajing , Williams James P , Douglas Peter M J , McKenzie Jeffrey M 
Published: November 2019

Abstract
Earthquakes occurring naturally or induced by human activities can damage surface and subsurface infrastructure. Oil and gas wells represent a category of subsurface infrastructure that can act as leakage pathways connecting oil and gas reservoirs, groundwater aquifers, and the atmosphere. The integrity of these wells can be compromised through a wide range of processes and contribute to groundwater contamination, greenhouse gas emissions, and air quality degradation. We estimate the increase in such subsurface leakage potential due to seismic activity through geospatial analysis of 579,378 oil and gas well and 196,315 earthquake (magnitudes greater than 1.0) locations in Oklahoma, California, and British Columbia. We perform density-based clustering analysis and point density mapping using ArcGIS. We combine the well and earthquake point density maps to identify hot spots of joint high well and earthquake densities. We find that oil and gas wells and earthquakes are clustered in space, with densities reaching ∼60 wells per km2 and ∼40 earthquakes per km2 in California. There are at least two hot spots where these clusters overlap in each state/province. In Oklahoma and British Columbia, the hot spots are more correlated with earthquake densities; while, in California, the hot spots are more correlated with well densities. Our findings indicate the need to investigate the role of earthquakes on wellbore leakage through additional analysis of earthquake characteristics, wellbore attributes, improved data collection, and empirical field studies for all oil and gas wells, including those that are abandoned. In particular, large scale geospatial analysis establishing the scope of the problem and empirical field studies focusing on identified hot spots are needed to understand potential environmental impacts of earthquakes, especially those induced by oil and gas activities.
Bayesian constraint relaxation
Authors: Duan Leo L , Young Alexander L , Nishimura Akihiko , Dunson David B 
Published: November 2019

SummaryPrior information often takes the form of parameter constraints. Bayesian methods include such information through prior distributions having constrained support. By using posterior sampling algorithms, one can quantify uncertainty without relying on asymptotic approximations. However, sharply constrained priors are not necessary in some settings and tend to limit modelling scope to a narrow set of distributions that are tractable computationally. We propose to replace the sharp indicator function of the constraint with an exponential kernel, thereby creating a close-to-constrained neighbourhood within the Euclidean space in which the constrained subspace is embedded. This kernel decays with distance from the constrained space at a rate depending on a relaxation hyperparameter. By avoiding the sharp constraint, we enable use of off-the-shelf posterior sampling algorithms, such as Hamiltonian Monte Carlo, facilitating automatic computation in a broad range of models. We study the constrained and relaxed distributions under multiple settings and theoretically quantify their differences. Application of the method is illustrated through several novel modelling examples.
A random-perturbation-based rank estimator of the number of factors
Authors: Kong Xinbing 
Published: November 2019

Summary
We introduce a random-perturbation-based rank estimator of the number of factors of a large-dimensional approximate factor model. An expansion of the rank estimator demonstrates that the random perturbation reduces the biases due to the persistence of the factor series and the dependence between the factor and error series. A central limit theorem for the rank estimator with convergence rate higher than root $n$ gives a new hypothesis-testing procedure for both one-sided and two-sided alternatives. Simulation studies verify the performance of the test.