bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecological risk estimation of heavy metal pollution in roadside dust of Ado-Odo Ota, Southwestern Nigeria
Authors: Emenike C P , Okwuonu E J , Tenebe I T , Omole D O , Nwani M , Afolayan O D , Oniemayin B I
Published: November 2019

Increased industrial, commercial and transport activities have constantly introduced air pollutants such as heavy metals in the atmosphere. Roadside dust samples were collected from 10 locations along Ota-Benin road, analysed for Cr, Cd, Co, Ni, Pb, Fe, Mn, Cu, As and Zn, and the ecological risk was evaluated for the heavy metals’ concentration in the roadside dust particles using the Hakanson method. The results revealed that Cd (3.103 mg/kg) and Cu (mg/kg) surpassed the threshold effect level. Pollutant source identification analysis revealed possible origin from motor oil, plastics, metalliferous extraction, dyes, and paints industries. The contamination factor for Ni was found to be at a moderate level in location SM8, SM9 and SM10 and a similar category was observed for Pb in location SM7, SM8, SM9 and SM10. Zn concentration in location SM5, SM6, SM7, SM8, SM9 and SM10 fell within the moderate contamination factor zone as well. Furthermore, the mean

E
r
i

of the individual metals in the sample region followed the order of Cd > Ni > Pb > As > Cu > Zn > Cr indicating a high risk associated with cadmium within the sample region.
Radiation Protection Strategies in Medical Diagnostic Centers in Lagos State, Nigeria
Authors: Adeniji A R , Ezema I C , Aderonmu P A , Adesipo A O
Published: November 2019

In recent years, Medical imaging has recorded a canonized level of advancement in the medical chronicles of achievement feats. This has made the diagnosis of ailments easy in reducing the death rate of patients. Imaging machines have different functions and some of them use radiation that is dangerous to the human body. Although radiation is important and it is needed for the patients in need of treatment but not needed by the machine operators, staff and visitors of the building where the imaging machines are been housed. The aim is to investigate different design and construction strategies employed to reduce transfer of radiation in various diagnostic imaging centres in Lagos State Nigeria; in order to reduce health risk associated during radiation emission in medical facilities. Qualitative method of research was adopted and data were collected via review of pertinent literature and field work of three diagnostic centres in the study area. The data were analysed using content analysis and presented with sketch and pictures. The finding reveals that lead lining was the most common material used to shield the different diagnostic rooms in the study area. This shielding was not only done for walls but also embedded in the doors. In addition, Lead glass was also used to protect the machine operators from radiation. Finally, this study recommended that other less harmful materials need to be explored for radiation shielding other than the use of Lead. For competency in Educational, professional, curricular practices and even hygienic exigencies; further research may advance investigations to find out other protective materials and strategies that are relevant to medical exploits as well as Architects design specification knowledge for the design of medical facilities.
The place of geoinformatics in waste management, sanitation and health risks prevention in Ado-odo/Ota local government area
Authors: Adeyemi G A , Onimowo D , Oniemayin B I , Eletu A A
Published: November 2019

Increasing population growth, lack of suitable waste treatment and disposal sites, in addition to inadequate equipment for waste recycling, poor town planning, accumulation of waste beside the roads and canals caused by inadequate waste collection and lack of enough data and information on waste generation could be observed as palpable causes of inadequate waste management in our societies, as well as sources of environmental pollution. This paper considered the applications of Geographic Information Systems in the selection of suitable land fill sites in Ado-Odo/Ota LGA. Geospatial data of the study area were obtained, buffer, overlay and intersection analysis were carried out to exclude non-suitable locations and identification of suitable sites. The suitable locations for landfill were selected, and we concluded that GIS is a veritable tool in qualitative decision making in environmental management and sustainable development.
Insight review on impact of infrastructural development in driving the SDGs in developing nations: a case study of Nigeria
Authors: Davies I E E , Nwankwo C O , Olofinnade O M , Michaels T A
Published: November 2019

The Sustainable Development Goals (SDGs) recognize the dominance of infrastructure as a panacea for the nation’s development to improve the quality of people’s lives. In Nigeria, inadequate infrastructure has impaired the prospect of attaining some of these SDGs. Some of the identified barriers causing the poor implementations of SDGs in Nigeria include poverty, poor accountability, inadequate domestic water supply, poor energy supply, poor human capital development initiatives, poor transportation and telecommunication networks, illiteracy level, and environmental degradation. But while the SDGs are a non-enforced agreement, the way and manner of implementation and the conditions under which the state acts in accordance with the agenda were not properly spelled out. However, the success of the SDGs in Nigeria requires commitment from government at all levels to provide adequate funding, financial prudence, stable polity, sound policies, availability of functional infrastructural facilities and ensuring value for money. This will result in achieved opportunities such as the establishment of new businesses, boosting of employment rate, ample growth opportunities, enhance risk-adjusted financial returns to investors, an increase in the rate of youth and adults in formal education and non-formal education, and promoting environment friendliness. This review further recommends that government should address the challenges faced in the area of power, telecommunication, corruption and access to agrarian areas in the country in order to have an inclusive infrastructural development that is positively driving growth. Moreover, assessment of projects should include initial capital investment, operational cost, maintenance, and disposal of the asset which will guarantee more sustainable infrastructure projects that are likely to perform much better through the lifecycle. Thus, successfully achieving the SDGs must involve innovative approaches to infrastructure financing and sustainable public procurement.
Ping-pong reduction for handover process using adaptive hysteresis margin: a methodological approach
Authors: Adewale A A , Ekong E E , Ibikunle F A , Orimogunje A , Abolade J
Published: November 2019

The technology, Long Term Evolution (LTE) developed by 3rd Generation Partnership Project is considered an improved standard in mobile communications when compared to previously attained network standards. LTE with prospects of decreased latency levels and support of downlink and uplink transmission at data rates exceeding 100Mbps and 50Mbps, an effective handover framework needs to be put in place to improve quality of service rendered to the network users and decrease wastage of network resources. This study examines several works carried out on a handover criteria (hysteresis margin) needed for designing an effective handover framework. This margin is based on the received signal strength between both target and serving eNodeBs, and its proper determination amongst other advantages mitigates the rate of unnecessary and repeated handover (ping-pong effect). The model presented in this research integrates the artificial neural network (ANN) mechanism into the determination of hysteresis margin in the LTE handover process which is to minimize handover delay and ping-pong taking into consideration the speed of the user equipment (UE).
Access to Information as a Veritable Strategy for Successful Entrepreneurship in a Developing Country
Authors: Okocha F , Eyiolorunshe T , Idiegbeyan-ose J , Aregbesola A , Owolabi S
Published: November 2019

The paper discussed information access as a useful strategy for successful entrepreneurship in a developing country. It started with the general introduction of the concept information and the role of information in entrepreneurship. It further discussed the strategic role of information access by entrepreneur in Nigeria as compare to other developed countries. It further highlighted the nexus between information and entrepreneurship, it also discussed the challenges of information provision to entrepreneur in Nigeria to include poor infrastructures, unreliable power supply, lack of internet access in most public libraries in developing countries among others, based on these discussion, it was concluded and recommended that the challenges so listed should be addressed in bridging the digital divide, and provision of infrastructures by government and other stake holders that are concerned. This will enable the entrepreneurs in developing countries measure up with those in developed countries and at the same time reduce unemployment and increase the Gross National Product of the country.
Women in banking: Career choice and advancement
Authors: Orbih M U , Imhonopi D
Published: November 2019

The purpose of this paper is to explore the factors that influenced the career choice and identify the barriers related to the career advancement of female bankers. Quantitative and in-depth interview methods were employed in this study. Close ended questionnaires were administered to female bankers in Metropolitan Lagos, Nigeria. Data were analysed using frequency counts, percentages and mean rankings. The findings showed that factors such as employment opportunities, hope for career advancement, personal skills, prestige and attractiveness of bank job, remuneration, educational qualification and job suitability influenced female bankers’ choice of a career. Family responsibilities, strict banking promotional policies and employment policies and practice were identified as barriers that impedes female career advancement. The study also discovered that there is no form of gender discrimination in the banking sector in Lagos state. The study concluded that the findings would help in the better understanding of the career development of female bankers in Lagos state, Nigeria. The study recommended that Banks promote the personal well-being of their female employees, introduce and effectively implement family friendly policies, and review the promotion and employment policies.
Evaluation of jig work on the basis of granulometric analysis of particle size fractions of benefication products in purpose of process optimization
Authors: Surowiak A , Foszcz D , Niedoba T
Published: November 2019

The analysis of hard coal jigging was conducted because of optimal recovery of useful fraction in concentrate and not useful fraction in tailings. The evaluation of the process was conducted on the basis of industrial sampling of coal dust jig and performed granulometric and densimetric analyses of collected products samples in laboratory conditions. In selected size-density fractions of partition products the yields of products were calculated and the amounts of ash and total sulfur were determined. On the basis of the results of granulometric, densimetric and chemical analyses of obtained size-density fractions, balance of partition products and appropriate calculations the beneficiation curves were created which allowed to evaluate the process because of optimization of device work in purpose of achieving higher recovery by possibly highest concentrate quality.

The evaluation of hard coal beneficiation results was done in the paper because of optimal recovery of organic phase in concentrate and mineral components in tailings in aspect of process monitoring. The analysis of obtained characteristics of ability to beneficiation was performed in purpose of selecting optimal technological factors for the needs of optimization of device work.
The efficiency of engaged capital in the WIG-mining index
Authors: Kruk S
Published: November 2019

The main goal of the article is to analyse the relationship between the level of debt and the level of efficiency of using the invested capital. The article is based on the analysis of the subject literature and the use of financial analysis tools. The analysis confirmed the relationship between the debt ratio and Return on Invested Capital. Conducted considerations should be treated as a starting point for further in-depth analysis regarding the impact of the capital structure on the effectiveness of the enterprise.
Influence of grinding media movement on the throughput of dry grinding circuit with electromagnetic mill
Authors: Foszcz D , Wołosiewicz-Głąb M , Krauze O , Ogonowski S , Gawenda T
Published: November 2019

The paper investigates how the movement of grinding media affects the throughput of dry grinding circuit with the innovative electromagnetic mill. General structure of the grinding circuit, control system and its advantages are presented. Three air flows are critical for determining material throughput and providing proper operating conditions of the installation: flow through the working chamber of the mill, through the main classifier and in the recycle stream. They are affected by the moving grinding media. To assess this influence, air speed measurements were taken for different positions of dampers in air streams, for several masses of grinding media and frequencies of the rotating electromagnetic field. For each air stream, a set of polynomial models was identified. Control scheme for the air flows was proposed, including compensation for grinding media movement. Introduction of hierarchical control and distribution of particular control tasks on different layers was necessary.
Technical, technological and environmental aspects of the management of technological waters in mines and concentrators owned by KGHM Polska Miedź S.A.
Authors: Witecki K , Grotowski A
Published: November 2019

Water and Tailing Management System (WTMS) plays a key role in mining and processing technological chain. In general, two separate but dependent systems can be separated: a network of technological waters and tailings. They constitute a system of connected vessels, a perfect example of which is the WTMS owned by KGHM Polska Miedź S.A. and managed by Hydro technical Department (O/ZH). The mining, technological and flotation water transport systems included in the system together with the accompanying facilities and installations cover the area of approx. 15 x 26 km. They combine 3 mines, 3 concentrators (ZWRs), Żelazny Most Tailing Management Facility (TMF) and the Głogów discharge station. This system makes it possible to conduct mining and processing operations by collecting water from mine workings (drainage), supplying concentrators and other installations (filling) with process water, flotation tailing management and discharge of excess water to the environment. The necessity of excess water discharge is associated with a positive balance of the system. This state results from the specific hydrogeological conditions and applied technological solutions, while providing the opportunity to work without the need to extract fresh water from the environment. Working in closed circuit, the technological water network fits in with the principle of the “circular economy”, while meeting the quality requirements of the water both for the sake of issued permits and the flotation process. The global trend in the management of flotation tailings is being observed towards deposition them in thickened form in order to increase the safety of TMF and the best sign in to the BAT requirements. Positive examples obtained in this field by KGHM were possible due to many years of research conducted not only in this direction but also on the reuse of flotation tailings.
Influence of grinding on flotation of industrial semi-product from sedimentary copper ore upgrading process
Authors: Ostrowski K , Bakalarz A , Duchnowska M
Published: November 2019

The effect of the grinding and liberation changes of sulphide minerals on their floatability in the flotation process of concentrate from rougher flotation from the Rudna Concentration Plant (KGHM Polska Miedz SA) was analyzed. It has been found that the upgrading selectivity decreases with the decreasing size of sulphide particles regardless of liberation degree. The best selectivity of flotation was observed for the fully liberated sulphides. Totally locked sulphides and minerals marginally liberated are characterized by very poor upgrading selectivity or even no upgrading. Moreover, for the smallest particles of sulphides (below 20 μm), despite of good liberation, very low selectivity of enrichment is observed. It was found that the application of one-stage grinding of concentrate from rougher flotation in separation circuit can result in higher upgrading selectivity of cleaning stages and higher content of useful minerals in final concentrate.
PSG method for the simulation of carbon particles accumulation in the flotation process
Authors: Kalisz D. , Kuglin K. , Młynarczykowska A.
Published: November 2019

Carbon agglomeration on the surface of gaseous bubbles in the flotation process has been modeled in this paper. The calculations were based on the PSG method and performed for five strictly defined size groups of carbon particles (M=5) for initial sizes 100-400 µm, and mixing energy ε = 0.01 [m2 s−3]. The analysis of the obtained results revealed that the process was much faster for particles with bigger initial size 300 and 400 µm. In this case the time needed for the removal of particles in particular size groups was shortest. It was observed for all analyzed cases that the process was most dynamic in the initial phase, whereas at the end of it the agglomerations considerably lowered because of the decreased number of particles in specific groups.
High-frequency induction heating of shrink-fitting parts of turbogenerators
Authors: Dzliev S V , Pishchalev K E
Published: November 2019

The advantages and disadvantages of induction heating by high-frequency currents during large-sized parts mounting and dismounting are studied. The deviations of the temperature field and the deformation field of the part from the axial symmetry with the horizontal position of the shaft are analyzed. Recommendations were developed on how to take into account these deviations in the technology of mounting and dismounting of the retaining rings of turbogenerators.
Modeling of sudden six-phase and three-phase short circuits of a six-phase turbogenerator
Authors: Chishko S D , Adalev A S , Korovkin N V
Published: November 2019

A demand for the highest possible power density in electrical machinery in some applications often requires a change in conventional and well-known three-phase stator winding solution. This paper discusses high-power turbogenerators with a six-phase winding. Mutual inductance between two three-phase windings requires updating of the equations for transient processes modelling. The equivalent circuits and equations for the dq0-reference frame are summarised, sudden six-phase and three-phase winding short circuit processes of the generator under load are modelled.
Motion control of mechatronic module for monitoring high voltage equipment
Authors: Shakhnin V A
Published: November 2019

The paper presents the algorithm for adaptive motion control of elements of mechatronic module for monitoring high-voltage equipment. The control principle is based on correction of motion parameters in accordance with current testing results. A modified evaluating-function method is used to interpolate the motion paths.
Identification of electric traction in the urban electric transport system
Authors: Aykhadeev A , Idiyatullin R , Kisneeva L , Bytakov V , Pavlov P , Litvinenko R
Published: November 2019

The article presents the results of a systematic review of the basis of formation and implementation of electric traction in the urban electric transport system. Its complexity is determined by the fact that various technical, technological, industrial and other subsystems and complexes are included in it, whose main purpose is to satisfy the needs of the population in transportation. Determining the basis for the formation and implementation of electric traction in the system of urban electric transport is a condition for finding methods and means of improving its efficiency, including the energetic one. Based on the proposed approach, urban electric transport was interpreted as a complex production and technical system, which allowed identifying electric traction as an electrical engineering complex, and at the same time as a technological system, and as a technological process of functioning of this system. The results of the study should be interpreted from the standpoint of synergistic ideas that will contribute to the development of the general theory of electric traction in the context of modern scientific methodology.
Control system for vector regulation of power flows in medium voltage network
Authors: Sosnina E N , Chivenkov A I , Lipuzhin I A , Vikhorev N N
Published: November 2019

The article is devoted to the device for automatic control of power flows in smart grids of medium voltage. A description of proposed method of vector regulation of power flows in a power transmission line using a solid-state voltage regulator (SSVR) is given. SSVR allows one to adjust the current in the line by introducing an additional EMF and changing the voltage drop across a network choke with known electrical parameters. A vector diagram of voltages and currents is given, explaining the principles of forming parameters of the current of the network choke. The Vector In and Vector Out virtual instruments for controlling the SSVR input and output voltage converters respectively are developed in the LabVIEW. Virtual instruments regulate the parameters of the vectors and implement the control of electrical potentials on the network choke. The test results of the developed control system confirmed the effectiveness of vector regulation.
Optimizing location and size of distributed generators based on the metaheuristic algorithms for solving network reconfiguration problem
Authors: Cuong L Q , Maclesov A M , Nguyen H D , Valeev I M
Published: November 2019

This paper demonstrates the method of optimizing the location and size of the distributed generators with the aim of reducing active power loss by changing the state of the existing tie and sectionalizing switches on the distribution network. A new algorithm is proposed to solve the distribution network reconfiguration problem based on the Runner-root Algorithm (RRA). In the first stage, the Runner-root algorithm is applied to solve the reconfiguration problem, and the next stage of optimizing the new distribution network configuration takes into account the influence of the location and the size of the distributed generators. The calculation results show that the proposed method can simultaneously solve the problem of optimizing the location and size of distributed generators when reconfiguring the distribution network. The results of the comparison with other studies in the same distribution network system 69 nodes showed that the proposed method is highly effective and can be used for reference in the process of optimizing the operating mode of a distribution network.
Influence of value resistance contact units of switching devices on losses of the electric power in shop networks of low tension
Authors: Gracheva E I , Naumov O V , Gorlov A N
Published: November 2019

The calculation of resistance tightening contact joints of switching devices allowing to consider technical condition of low-voltage switching equipment and to specify the value of the energy emitted in the switching device in the mode of operation electrical networks is presented in article.
Induction plasma heating installation for heat treatment of powder materials
Authors: Lopukh D B , Martynov A P , Vavilov A V , Skrigan I N
Published: November 2019

In this article the work results on the creation at the Department of Electrotechnology and Converter Engineering in ETU “LETI” of a high-frequency induction plasma research installation designed for high-temperature plasma treatment of powder oxide and other materials in order to obtain melted spheres and different dispersion and structure powders, as well as high-temperature plasma surface treatment to give them special properties are presented. The device has already started operation and is currently producing various oxide materials. The operation characteristics of the HFI-plasma torch and the processed materials during powders spheroidization of quartz sand, electro corundum, phosphate glass and melted stabilized zirconium dioxide are obtained.
Numerical simulation of the induction heating process of a disk profile
Authors: Mannanov E , Galunin S
Published: November 2019

This paper presents the developed parametric 3D model of disk heating. The numerical results reflect the change in the temperature profile of the heated pattern depending on the current value, current frequency, air gap size, workpiece thickness, workpiece diameter, heating time, number of inductor turns used and geometrical position elements of the systems “inductor - disk”. The results can be used for parametric studies and setting up the operation mode of installations for various sizes of disks.
The method of calculating the setpoint of the overcurrent protection with the function of the detuning from inrush currents for a circuit breaker on the basis of the electronic trip unit
Authors: Bystrov A , Neelov A
Published: November 2019

This paper presents for the first time an attempt to specify the method for calculating the value of the overcurrent protection setpoint with the function of detuning from inrush currents for the electronic trip unit ETU. The principle of protection is described in detail on the basis of comparing the rate of current rise in the protected circuit with the settings recorded in the ETU memory in the form of a binary code. The algorithm of action for the ETU based on the digital signal controller DSC is presented. Methods are proposed for improving the reliability of overcurrent protection and reducing the number of false outages. The procedure for calculating protection settings has been considered. Moreover, previously developed methods for calculating protection settings with a detuning from inrush currents are not suitable for the principle described in this work and vice versa the presented method for calculating protection settings with detuning from inrush currents is not suitable for methods based on other principles.
Analytical studies of transformers operating modes in supply and distribution electric network of a field substation
Authors: Tabachnikova T , Makht A , Nurbosynov E
Published: November 2019

We obtained new analytical dependencies for investigation of operating modes of power transformers, supply and distribution electric network of a field substation in order to take into account losses of power and electrical energy in all network elements. We substantiated the relevance of this article and the considered tasks, which depend on the object of study. It has been established that one auxiliary transformer and from eight to ten outgoing lines are connected to one bus section of a power transformer of a field substation. We developed mathematical models of electrical complexes of a field substation with individual transformers of outgoing power lines, as well as with individual, node and centralized compensating units. We obtained new analytical dependencies, taking into account total losses of power and electrical energy in power transformers of field substation and distribution electrical network as a function of supply voltage. The well-known method for calculating the energy parameters of electrical units of field substation and auxiliary equipment has been improved by adding new analytical dependencies of total power losses in power transformers of field substation and distribution network as a function of 35 kV supply voltage. The scientific novelty of this work is obtaining new analytical relationships between total power loss in power transformers of the field substation and distribution network in a function of supply voltage, which take into account external and internal disturbances in the network. This allowed us to improve the well-known method for calculation the energy parameters of electrical installations of a field substation taking into account parameters of individual, nodal and centralized compensating installations.
Practical aspects of modeling of the oil and gas producing enterprise’s electrotechnical complexes
Authors: Petrochenkov A B , Romodin A V , Mishurinskikh S V
Published: November 2019

When planning technological modes of the power supply systems of oil and gas production enterprises, modeling of their operating parameters is a very important task. The currently used models of interaction between hydromechanical and electrical systems, as a rule, are built using multi-circuit equivalent circuit. This leads to a significant expenditure of computational effort and is not always suitable for rapid assessment. The purpose of this paper is to develop the technique for modeling the operating parameters of the power supply system operation using single-circuit equivalent circuits, as well as taking into account the current technological parameters. In the proposed technique, the interaction between electrical and hydromechanical systems is shown. Use of this technique allows taking into account the influence of the magnetization current of power transformers without adding another branch into the equivalent circuit.
Application of common-mode-free control topology to a two-level inverter
Authors: Vostrov K , Frolov V
Published: November 2019

The use of asynchronous motors in electric drive systems has become widespread and convenient. Also, since the frequency converters became wide-spread and popular devices, induction motors became the most popular machine type in both constant- and variable-speed applications. However, the conventional two-level frequency converter’s output three-phase waveform is not fully repeating ideal sine waves provided from the grid. The so-called common-mode voltage appears because of specifics of the converter operation and works as the source of harmful parasitic phenomena of bearing currents. Flowing through the motor bearings, these currents providing a list of undesirable effects, finally causing the bearing properties degradation and early system failure. Current paper deals with the novel control method described earlier and show the method implementation by the means of the two-level frequency converter.
Investigation of composite material destruction under lightning stroke effect
Authors: Boronin V N , Minevich T G , Kochetkova E Y , Smorgonskiy A V , Kolodkin I S
Published: November 2019

Destruction processes of composite materials under lightning stroke effect have been studied. The results of characteristic damages of samples have been presented upon a series of tests conducted with standard lightning currents and those ones whose shape is close to actual lightning stroke. There have been exhibited distinctions between the levels of sample damages: in the second case significant damages of composite matrix external layers have been shown, among which multiple destructions of bundles of carbon fibers at a depth of several layers, layer delamination and cavities formed inside sample. There have been described the results of generalized analysis of damages obtained by applying nondestructive inspection methods: stereoscopic microscope investigation and X-ray microtomography. The mechanism of damages has been presented on the basis of obtained data. The results of testing electrical, mechanical, thermal properties of composite samples have been given upon a set of experiments for lightning current resistance.
Method of automated synthesis of the logic part of relay protection device which increases its sensitivity
Authors: Kulikov A L , Loskutov A A , Mitrovic M
Published: November 2019

Often there are such modes of operation in the electric power systems where standard methods of relay protection and automation become insufficiently effective. For example, such modes are typical for electric networks with distributed generation and renewable energy sources. Today, the task of developing new digital relay protection methods, that have high technical excellence and fully comply with the requirements of IEC 61850, is relevant. A method of organizing the logical part of multiparameter relay protection is proposed, which improves its sensitivity. The method is based on the criterion of minimizing the average risk of decision making and solving the task of abstract synthesis of automata theory. The application of the proposed method is considered on the example of multidimensional relay protection with five measuring fault detectors and the implementation of simulation models in the Matlab/Similink software package.
Development of relay protection system allowing taking into account seasonality when determining operation setpoints
Authors: Akhmedova Olga , Soshinov Anatoly , Bakhtiarov Konstantin , Atrashenko Olga , Panasenko Mikhail , Kopeykina Tatyana
Published: November 2019

Various manufacturers of relay protection devices only offer two options of setpoints, which should be changed manually by the operating staff at the place of protection installation. This means that these devices do not have the ability to adapt the protection response current to changing environmental parameters, which have a significant impact on overhead power lines parameters. As a result, the setpoint set on a microprocessor relay device is not always correct and can lead to failure of the relay protection or to a false positive.
The influence of air inflow in the vacuum system of a cogeneration steam turbine plant on its energy performance
Authors: Shempelev Alexander , Iglin Pavel
Published: November 2019

The article considers the issue of the influence of air inflow in the vacuum system of a cogeneration steam turbine plant on its energy performance. The authors give a brief description of characteristics of a steam turbine condenser. On the example of the T-110/120 turbine plant, they estimate the power loss factor of a low pressure section (LPS) depending on air inflow in a vacuum system on a heat schedule operating mode with steam consumption of 20 t/h. The authors underline a significant influence of air inflow on the amount of power produced by the turbine plant. Moreover, the authors evaluate the power loss of LPS depending on air inflow in the vacuum system on one of the operation modes on the electrical schedule. They demonstrate that an increase in air inflow leads to quite large (hundreds of kilowatts) power losses.
Method of heat exchangers calculation for combined-cycle gas turbine plants in operation modes that differ from the nominal ones
Authors: Fomin V , Kalyutik A
Published: November 2019

We carried out a comparison of methods for calculating heat exchangers of combined-cycle gas turbine plants (CCGTP) in variable-load operation modes. It is shown that for calculations of waste heat boilers with complex thermal circuits and a large number of heat exchangers it is advisable to use approximate methods for calculations.
Multi-level model of the centrifugal compressor workflow for its effective optimization
Authors: Egorov Igor , Volkov Andrey , Popov Grigorii , Baturin Oleg
Published: November 2019

The paper presents the main ideas of the virtual test bench concept for rapid obtaining of the reliable characteristics of compressors based on a multi-level mathematical model with a two-step identification using data obtained from mathematical models with a high order of accuracy. One of the possible identification algorithms and the results of its successful testing are given on the example of a centrifugal compressor stage developed and tested at NASA.
Technology trends for LNG compression using innovative electric solutions
Authors: Durantay Lionel , Laboube Pierre
Published: November 2019

During the last 30 years, there has been a significant evolution and innovation of electric driven compressors in replacement of steam or gas turbines. Technology trends are highlighted in this paper with a focus on LNG Compression, covering standalone and integrated compression fed by Variable Frequency Drives (VFDs), and the emergence of the induction squirrel cage motor up to 120MW.
Compact household wind generator
Authors: Galuschak V , Soshinov A , Elfimova O , Shevchenko N , Lebedeva Yu
Published: November 2019

Nowadays, there is a problem of further development of alternative energy for power supply of residential consumers. One of the areas of alternative energy is wind power. Wind generators offered to the public do not fully meet the requirements for household wind turbines. They are characterized by high cost; large weight and dimensions; installation complexity; impossibility of installation in cramped conditions; high noise and vibration. The article presents a physical model of a household wind generator with a wind guide device. Mass, dimension and energy characteristics of this de-vice are estimated. The presented construction of a household compact wind turbine can be used for power supply of residential consumers, small businesses, in the field of housing and communal services and in agricultural sector.
Sun tracking system for photovoltaic batteries in climatic conditions of the Republic of Cuba
Authors: Gerra D D , Iakovleva E V
Published: November 2019

Annotation. Today, the efficiency of solar power plants in the Republic of Cuba is low, despite the high level of technology development in this area. The article presents the results of the analysis of the potential of solar energy in the territory of the Republic of Cuba. This paper presents the results of experimental studies, the purpose of which is to increase the efficiency of using photovoltaic stations. The developed two-axis sun tracking system is described. This tracking system increases the conversion efficiency of solar energy into electrical energy in photovoltaic modules.
Piezoelectric Micro-dosing System for Spiking Quality Samples in Occupational Hygiene Laboratories
Authors: Giesen Yvonne , Nürnberger Franziska , Gusbeth Krista , Mühlberg Ann-Kathrin , Lamm Nils , Schwab Gregoria , Breuer Dietmar
Published: November 2019

Quality control is crucially important in the arena of chemical analysis. Reference materials are essential for calibration and quality control processes, and for verification of the accuracy and reliability of the analytical results obtained. Owing to the complexity of their manufacture, reference materials for chemical agents occurring at workplaces are expensive and available only on a limited scale and for a small number of substances. Therefore, their cost-effective and fast production is an important aim. The Institute for Occupational Health and Safety (IFA) of the German Social Accident Insurance (DGUV) currently pursues different strategies for the production of reference materials. One strategy entails the use of a piezoelectric micro-dispensing system for non-contact spiking of extremely small quantities of substances with high reproducibility. The dispensing system is coupled to a semi-automated assembly unit for loading high numbers of samples. It is used for spiking phosphoric and sulphuric acid onto quartz fibre filters. Comparison of the results obtained on different days shows higher variability than results observed on the same day. However, after daily adjustment of the number of droplets to the current droplet volume, highly reproducible series with an adequate number of samples (>500) could be realized. The results of the internal quality control were verified in an interlaboratory comparison. Furthermore, storage stability was investigated systematically over a period of 2 years. The samples produced are suitable for use as reference materials for both inorganic acids.
Engagement in Care, Viral Suppression, Drug Resistance, and Reasons for Nonengagement After Home-Based Same-Day Antiretroviral Therapy Initiation in Lesotho: A Two-Year Follow-up of the CASCADE Trial
Authors: Amstutz Alain , Brown Jennifer Anne , Ringera Isaac , Muhairwe Josephine , Lejone Thabo Ishmael , Klimkait Thomas , Glass Tracy Renée , Labhardt Niklaus Daniel
Published: November 2019

Background

The CASCADE trial showed that compared with usual care (UC), offering same-day (SD) antiretroviral therapy (ART) during home-based human immunodeficiency virus testing improved engagement in care and viral suppression 12 months after diagnosis. However, questions remain regarding long-term outcomes and the risk of propagating drug resistance.

Methods

After completion of the primary endpoint at 12 months, participants not in care in both arms were traced and encouraged to access care. At 24 months, the following outcomes were assessed in both arms: engagement in care, viral suppression, and reasons for nonengagement. Furthermore, we explored the acquisition of drug resistance mutations (DRMs) among SD arm nonlinkers.

Results

At 24 months, 64% (88/137) in the SD arm vs 59% (81/137) in the UC arm were in care (absolute difference [AD], 5%; 95% confidence interval [CI], −6 to16; P = .38) and 57% (78/137) vs 54% (74/137) had documented viral suppression (AD, 3%; 95% CI, −9 to 15; P = .28). Among 36 participants alive and not in care at 24 months with ascertained status, the majority rejected contact with the health system or were unwilling to take ART. Among 8 interviewed SD arm nonlinkers, 6 had not initiated ART upon enrollment, and no acquired DRMs were detected. Two had taken the initial 30-day ART supply and acquired DRMs.

Conclusions

SD ART resulted in higher rates of engagement in care and viral suppression at 12 months but not at 24 months. Leveling off between both arms was driven by linkage beyond 12 months in the UC arm. We did not observe compensatory long-term disengagement in the SD arm. These long-term results endorse SD ART initiation policies.

Clinical Trials Registration

NCT02692027.
Habitat use of spring migrating dabbling ducks in the Wabash River Valley, USA
Authors: Williams Benjamin R , Benson Thomas J , Yetter Aaron P , Lancaster Joseph D , Hagy Heath M
Published: November 2019

Stopover sites provide crucial habitat for waterfowl to rest and refuel during migration. Knowledge of which land-cover types are of greatest importance to migrating waterfowl and how the surrounding landscape influences their use can inform management decisions and conservation plans to adequately meet resource requirements. Specifically, spring migration habitat is essential for waterfowl preparing for breeding yet is an understudied period of the life cycle. We placed radio-transmitters on Mallards (Anas platyrhynchos) and Green-winged Teal (Anas crecca) between January and April 2016–2017 in the Wabash River Valley of Illinois and Indiana to assess habitat use and movement patterns. Both Mallards and Green-winged Teal primarily used emergent and woody wetlands, with 89% of use points in these land-cover types even though they made up <5% of the study area. Use of both dry and flooded row crops was minimal. While habitat selection of Mallards was similar for diurnal vs. nocturnal periods, Green-winged Teal used emergent wetlands at a higher rate during the day and shifted to woody wetlands at night. In general, sites surrounded by greater amounts of open water, upland forest, and upland herbaceous/grassland cover were more likely to be used than areas surrounded by row-crop agriculture. Additionally, private and public lands enrolled in conservation easement programs (such as the Wetlands Reserve Program) were frequently used by migrating waterfowl compared to other protected or public lands. These findings highlight the importance of a landscape-level approach to conservation, specifically focusing on wetland restoration while minimizing reliance on agricultural fields to fulfill habitat needs during spring migration in the Midwest.
The ignorant monopolist redux
Authors: Koenker Roger
Published: November 2019

The classical problem of the monopolist faced with an unknown demand curve is considered in a simple stochastic setting. Sequential pricing strategies designed to maximize discounted profits are shown to converge sufficiently rapidly that they leave the monopolist ignorant about all but the most local features of demand. The failure of the monopolist to 'learn' his demand curve would seem to call into question some standard assumptions about agents’ grasp of their economic environment.
Fertilizing Corn With Manure Decreases Caterpillar Performance but Increases Slug Damage
Authors: Rowen Elizabeth , Tooker John F
Published: November 2019

Many farmers use manure as an alternative to inorganic fertilizer. Previous research has shown that manure can decrease plant susceptibility to herbivores, but the mechanisms remain unclear. To determine how manure affects herbivore performance in a greenhouse setting, we fertilized corn with stacked cow manure or an equivalent amount of NPK fertilizer and measured caterpillar development, plant nutritional content, and defenses. After 4 wk of growth, we allowed fall armyworm (Spodoptera frugiperda) or black cutworm (Agrotis ipsilon) caterpillars to feed on these plants for 6 d. Compared to inorganic fertilizer, manure reduced mass-gain of black cutworm caterpillars and smaller fall armyworms. We paired this greenhouse experiment with a 3-yr field experiment, which incorporated a wheat cover-crop treatment crossed with the two fertilizer treatments in a 2 × 2 factorial design. We measured plant damage early in the season from naturally occurring herbivores and measured neonate fall armyworm performance on field-collected leaf tissue. In 2017, corn in manure-fertilized plots sustained more herbivore damage, primarily driven by a higher incidence of slug damage. Fall armyworm performance, however, was lower on leaves collected from manure-fertilized plants. In contrast to previous studies, we did not find increased micronutrients or enhanced defenses in manure treated plants. While manure can offer resistance to some herbivores, our results suggest that this resistance can be overshadowed by habitat conditions.