bluuebunny/crossref_metadata_2025_split huggingface dataset:
Promising directions for the use of heat from low-potential sources of chemical production
Authors: Fedyukhin A. V. , Zvonchevsky A. G. 
Published: June 2022

THE PURPOSE. Development of promising directions for improving the technology of an oil refinery (refinery) based on the use of heat from low-temperature sources of the primary oil distillation system.METHODS. The analysis of the technological scheme of the refinery carried out, in order to identify the most energy-intensive system, while using the methods of analytical and thermodynamic analysis. The analysis of energy use in the circuit of an electric desalination plant (EDP) is carried out according on the basis of the data of the technological regulations of the existing EDP-AVT-7. The assessment of the feasibility of the proposed directions and developed solutions was carried out on the basis of the methods of technical, economic and environmental analysis.RESULTS. This article shows the relevance of the problem and substantiates the importance of its consideration for improving energy and environmental efficiency. Based on a common scheme for the primary processing of crude oil, it is noted that this technology has significant energy saving potential. It is proposed to implement promising directions for the rational use of heat, and a modernization solution is presented aimed at improving the technological elements of the EDP-AVT-7 circuit based on the heat recovery of the hydrocarbon vapor-gas mixture.CONCLUSION. The proposed directions and developed measures for the use of heat from low-grade sources in the refinery scheme show their promise due to a significant reduction in technological energy losses, a reduction in fuel consumption and an increase in the efficiency of its use, which, in general, will positively affect the economic and environmental situation in the region.
Thermal and aerodynamic parameters radiation chambers of the hydrocarbon pyrolysis furnace
Authors: Vafin D. B. 
Published: June 2022

THE PURPOSE. To carry out mathematical modeling of interrelated physicochemical processes in radiation chambers of tubular furnaces of pyrolysis of hydrocarbons. Perform numerical calculations of heat and mass transfer in the furnace furnace chamber with a multi-tiered arrangement of wall burners on the side lined walls.METHODS. Using our own package of applied programs based on the numerical solution of a system of differential equations of energy conservation and equations of radiation gas dynamics, the fields of velocities and temperatures of natural gas combustion products in the radiation chamber of a hydrocarbon pyrolysis tubular furnace are calculated. Interrelated processes of natural gas combustion, radiant-convective heat transfer, and turbulent flow of flue gases take place in the radiation chamber. These processes are modeled by two-dimensional equations of the combustion model, energy transfer by radiation, and equations of motion. In the side walls of the radiation chamber on both sides in eight horizontal tiers there are wall burners in the amount of 128 pieces. Combustion products emerging from the nozzles of these burners create complex velocity and temperature fields in the chamber volume. Due to the radiation of flue gases, the smallest soot particles and hot lined walls of the radiation chamber, heat flows are formed to the tubular screen, where hydrocarbons are pyrolyzed to produce ethylene.RESULTS. As a result of calculations, the velocity fields, the temperature in the volume of the radiation chamber and the concentration of the main components of the combustion products were obtained. Local values of surface densities of radiant heat fluxes to reaction pipes for methane and propane pyrolysis furnaces are calculated. Comparisons of some of the results obtained with the readings of the devices of existing technological installations are carried out.CONCLUSION. Calculations show that the developed software package makes it possible to obtain realistic values of local velocities and temperatures in the radiation chambers of tube furnaces, surface densities of convective and radiant heat fluxes to boundary surfaces, and other thermal and gas-dynamic parameters in the furnace volume. With a multi-row arrangement of a large number of wall burners of low thermal power, a complex field of temperature and velocities of combustion products in the furnace volume is formed on the side walls of the radiation chamber of the furnace. At the same time, this arrangement of the burners ensures a fairly uniform distribution of heat flows over the surface of the tubular screen of the hydrocarbon pyrolysis furnace.
System analysis methods and resource-saving electromembrane technologies in creating a low-flow water system using of Tatarstan Republic energy facilities
Authors: Chichirov A. A. , Filimonova A. A. , Chichirova N. D. , Minibaev A. I. 
Published: June 2022

THE PURPOSE. theoretical substantiation of resource-saving technologies and development of "terminal" electromembrane installations when creating a low-flow water use system for energy facilities of the Republic of Tatarstan.METHODS. In the work, the methods of system analysis were used and a mathematical model was developed to describe it. The description and technical characteristics of the developed devices and installations for testing the proposed technologies are presented.RESULTS. At Kazan CHPP-3, a technology was developed and a pilot electromembrane plant was installed for the disposal of blowdown water from the thermal desalination complex. As a result of the operation of the electromembrane unit, a transparent alkaline solution is formed with a pH of 13.86 and a concentration of OH ions of 2.7% (up to 4%). The content of salt components in the concentrate is 2% by weight. The resulting concentrated alkaline solution can be used in the cycle of the station for the regeneration of anion exchange filters of the 1st stage. The softened saline solution is fed to the heating network. The electromembrane plant processes 0.5 tons per hour of alkaline wastewater with a ratio of concentrated alkaline solution to softened brine of 1:9. The specific power consumption is 6 kWh per 1 ton of blowdown water. The operation of the plant is characterized by the complete absence of waste and bezreagnosti. At the ion-exchange water treatment plant of the Nizhnekamsk CHPP-1, a method was proposed, a technology was developed, and an experimental pilot plant was installed for processing alkaline spent regeneration solutions of anion-exchange filters. The electromembrane plant processes 1.5 tons per hour of alkaline waste. The capacity of the plant is 0.1 tons of 4% alkaline solution. Specific power consumption - 4 kWh per 1 ton of alkaline waste solutions. During the operation of the installation, there is a complete absence of waste with a reagent-free wastewater disposal process.CONCLUSION. The return of regenerated alkali solutions and softened water to the production cycle makes it possible to obtain a significant improvement in indicators that characterize environmental friendliness and resource saving without the use of chemical reagents.
Laboratory model of the Savonius rotor
Authors: Guseva Yu. V. , Kostryukov S. A. , Vasilev A. R. 
Published: June 2022

THE PURPOSE. Increasing the efficiency and efficiency of power plants based on renewable energy sources should be carried out by improving technological, constructive, organizational, legal, technical and economic measures. Proposals are given for the development of approaches to assessing the efficiency of wind power plants based on the Savonius rotor. The design parameters are substantiated and a physical model is created for a comprehensive study and performance characteristics in laboratory conditions.METHODS. Based on the methods of physical and mathematical modeling of structures and profiles of wind turbine blades, the technical and economic indicators of various profiles of the blades of the Savonius rotor are determined.RESULTS. The theoretical substantiation of the design and various profiles of the blades of the Savonius rotor is carried out. On the basis of a comprehensive study of performance characteristics in laboratory conditions, the values of the wind energy efficiency coefficient, the rotation frequency of the wind wheel profile, and electric power were established.CONCLUSION. The results of the study can be applied to substantiate the widespread use and creation of wind power plants with a Savonius rotor to ensure high-quality and reliable power supply to remote consumers of electric energy, the creation of isolated power systems and the further development of alternative energy sources in the domestic electric power industry
Profil Pemecahan Masalah Matematika Berdasarkan Teori Polya Ditinjau dari Kemampuan Matematika Siswa
Authors: Putri Sekartaji Machdalena Sari , Putri Rani Kurnia 
Published: June 2022

Kemampuan dalam memecahkan masalah perlu dimiliki seluruh siswa. Selama ini yang menjadi masalah ialah bagaimana kemampuan memecahkan masalah dikembangkan pada proses belajar mengajar terutama matematika. Terdapat kesulitan siswa memecahkan masalah perlu mendapatkan perhatian dan di identifikasi secara lanjut. Tujuan penelitian ini untuk menggambarkan profil pemecahan masalah matematika berdasarkan teori Polya dengan tinjauan kemampuan matematika siswa. Metode penelitian yang dipergunakan yaitu kualitatif, sedangkan jenisnya deskriptif. Subjek penelitian ini terdiri atas subjek berkemampuan matematika tinggi, sedang, dan rendah. Teknik pengumpulan data yang dipakai yaitu teknik tes dan wawancara. Analisis data yang digunakan yakni hasil tes kemampuan matematika, hasil tes pemecahan masalah dan dikuatkan dengan hasil wawancara. Hasil penelitian menerangkan siswa dengan kemampuan matematika tingkat tinggi bisa mengatasi permasalahan, dan mengumpulkan informasi untuk mengatasi permasalahan tersebut. Tetapi pada akhir perhitungannya siswa kurang teliti. Siswa yang berkemampuan matematika tingkat sedang dapat mengumpulkan informasi pada soal yang disediakan, namun siswa melakukan kekeliruan dalam menentukan rumus. Sedangkan siswa dengan berkemampuan matematika tingkat rendah belum mampu memahami permasalahan dan mengumpulkan informasi secara jelas. Penelitian ini juga menunjukkan bahwa subjek penelitian tetap berada pada posisi pemahaman pemecahan masalah yang baik pada setiap tingkat kemampuan matematika siswa. Meskipun saat ini siswa melakukan sekolah dari rumah dikarenakan keadaan pandemi Covid-19.
Resume pasar bebas dan kebijakan pemerintah
Authors: Idil  
Published: June 2022

Perdagangan bebas merupakan suatu kegiatan jual beli produk antar negara tanpa adanya kerumitan aturan atau birokrasi yang mengatur perdagangan bebas itu didalam suatu Negara. Sehingga, suatu Negara, perusahaan, atau perorangan sekalipun dapat menjual produk yang diciptakannya di luar negeri
A study on coronary bifurcation lesions and procedural outcome at Manmohan cardiothoracic vascular and transplant center, Kathmandu, Nepal
Authors: Poudel Chandra Mani , Shakya Smriti , Gajurel Ratna Mani , Shrestha Hemant , Devkota Surya , Thapa Sanjeev , Manandhar Bhawani , Khanal Rajaram 
Published: June 2022

Background and Aims: Coronary bifurcation lesions are associated with high atherosclerotic plaque burden due to turbulent blood flow and high shear stress. There are various strategies for bifurcation stenting however, they are often prone to major cardiac events during percutaneous coronary intervention. The aim of this study was to assess the clinical profile and procedural outcome of patients with coronary bifurcation lesions.
Methods: This retrospective study was carried out at Manmohan Cardiothoracic Vascular and Transplant center, Kathmandu, Nepal. Two hundred and eight patients were enrolled in this study who had coronary bifurcation lesions seen on invasive coronary angiography from August 2017 to October 2021. The procedural complications were assessed.
Results: The mean age of patients with coronary bifurcation lesions was 61.48±11.19 years. Out of total 208 patients, 77% were males. True bifurcation lesion was seen in 65.4% of patients. Left anterior descending artery with diagonal was the most common bifurcation lesion (67.3%). The provisional stenting was done in 80.8% of patients and rest underwent 2-stent strategy. The complications mainly observed during the provisional stenting were plaque shift and side branch dissection.
Conclusion: The provisional stenting is the most preferred and suitable technique for most bifurcation lesions if technically feasible.
TO THE ISSUE OF REASONABLE AMOUNT OF QUALITY ENERGY IN THE ENTERPRISES’ POWER GRIDS
Authors: Kachan Yu. , Shram O. 
Published: June 2022

As known, the quality of electricity directly affects the operation of power consumers of all industrial enterprises as a whole. The purpose of this study is to analyze the existing limitations on the quality of electricity in the networks of industrial enterprises, as well as to assess the amount of electricity consumed by the enterprise, which must meet the requirements for its quality. To improve the level of electricity quality in the power networks of industrial enterprises, a number of technical and organizational measures are proposed. The first of these include the use of passive and active filters of higher-order harmonics, linear inductors, dynamic voltage distortion compensators, installation of voltadic transformers, etc. Organizational measures include optimization of the circuit and operating modes of the network, voltage regulation, phase load balancing, etc. Knowing the list of all the technical means used to improve the quality of electricity at any enterprise and the share of their total load capacity in relation to the consumed, it is possible to calculate the average added value for electricity that takes place in a particular case. Estimation of reasonable amount of high-quality electricity on the example of repair and mechanical workshop of metallurgical enterprise is carried out. According to the data, the installed power of electric power consumers, which meet the proposed criteria I, II and III are respectively 276 kW, 178.5 kW and 94 kW. As a percentage, it is 50.32 %, 32.54 % and 17.14 % of the total capacity of the workshop. Existing restrictions on the quality of electricity in the networks of industrial enterprises from an economic point of view are not advisable, since for a significant number of their consumers they are too rigid. The installed power of electricity consumers whose operation mode depends significantly on its quality, for different enterprises ranges from 20 % to 50 %. The added cost for electricity required to ensure its quality when using various technical measures in this regard ranges from 0.2... 0.35 UAH/k Wh, which is 5... 8 % of its commercial value. Electricity consumers should be divided into categories regarding the reasonability for them of the requirements for the quality of electricity necessary to ensure the normal operation of the equipment and the technological process.
INVESTIGATION OF MODES JOINT OPERATION OF HEAT UTILIZERS AND BOILER UNITS
Authors: Klimov R. , Sokolovska I. , Kozyreva Y. 
Published: June 2022

Given the share of energy consumption by powerful industrial enterprises in the overall balance of world consumption, it can be shown that at this stage of technology development, primary energy is not used efficiently enough, turning more into unused heat. Increasing the use of secondary energy resources reduces the consumption of primary resources, the cost of which is constantly growing, and solves the problem of improving the environmental situation in the locations of large enterprises. Thermal secondary energy losses are reduced by installing tail heating surfaces, such as economizers and air heaters.
The operation of the boiler unit is characterized by changes in its basic parameters over time, largely depending on the degree of load on the boiler. The degree of loading of the economizer affects the efficiency of its work. Determining the parameters of joint operation of heat recovery units and the boiler unit with changes in heat capacity will determine the most rational modes of operation of the system in terms of fuel economy.
The aim of the study is to determine the characteristic indicators of joint operation of the boiler unit at different degrees of its load, with heat recovery units installed in the required amount to determine the most efficient modes of operation of the system.
Economizers have the lowest thermal efficiency at a load of about 40% of the boiler power, and the highest at rated load. The results of calculations of the joint operation of the boiler unit with heat recovery units show significant changes in the possible cooling temperature of the combustion products behind the boiler when the boiler load changes. Using the above technique, it is possible to determine such a combination of the number of utilizers and different distribution of combustion products between them, at which the optimal gas temperature can be achieved for each specific mode of operation of the installation.
HEARTH SIZE TRENDS IN NEW AND MODERNIZED BLAST FURNACES
Authors: Kuznetsov M. , Kryachko G. , Sigarev E. 
Published: June 2022

The efficiency and effectiveness of blast-furnace smelting largely depends on the parameters hearth and its mode of operation. The purpose work is to identify trends in the design hearth of blast furnaces. To achieve the goals set, we used project and practical information on the issue under study for a long period of time from the 70s of the last century to the last decade of the XXI century. To assess the changes that have occurred, in addition to the absolute dimensions hearth (diameter, height and relative useful volume hearth to the countercurrent part of the furnace), indicators were used that indirectly assess the load hearth volume on the heat supply of one tuyere hearth and load hearth volume on the exhaust system blast furnace. The proposed indicators determine share useful volume of the hearth per one air tuyere, and the share of the useful volume of the hearth related to one cast-iron tap-hole. It is shown that the transition from designing high hearths with dg > 6 m to hearths with dg < 6 m occurred as early as in the 70s of the XX century. The absolute height hearth modern furnaces medium (dg = 11—12 m) and large (dg > 12 m) volume is in the range of 4,5÷5,4 m with slow growth with an increase in the useful volume of furnaces. The range fluctuations relative useful volume hearth relative to the volume countercurrent part furnaces within 0,15 ÷ 0,22 and its certain increase with an increase in the useful volume of the units is established. The reason for the absence of changes in Vkg /Vpr for the reconstructed typical Soviet furnaces, despite increase in the height hearth, is the preservation excessive height countercurrent part of the furnaces. When designing the design of the hearth of new and upgrading existing furnaces, it is recommended to maintain the values ​​of Vkg /nf and Vkg/nchl at the minimum possible level due specifics installation of tuyere devices and maintenance exhaust system of blast furnaces.
Evaluating caregiver stress in craniosynostosis patients
Authors: Tang Alan R. , Chen Jeffrey W. , Sellyn Georgina E. , Chen Heidi , Zhao Shilin , Gannon Stephen R. , Shannon Chevis N. , Bonfield Christopher M. 
Published: June 2022

OBJECTIVE
Caregiver stress from a child’s diagnosis can impact a caregiver’s ability to participate in treatment decisions, comply, and manage long-term illness. The aim of this study was to compare caregiver stress in children with craniosynostosis at diagnosis and postoperatively.

METHODS
This prospective study included caregivers of pediatric patients with craniosynostosis receiving operative intervention. Demographics and Parenting Stress Index, Short Form (PSI-SF) and Pediatric Inventory for Parents (PIP) surveys at baseline (preoperatively) and 3 and 6 months postoperatively were completed. PSI-SF scores between 15 and 80 are considered normal, with > 85 being clinically significant and requiring follow-up. Higher PIP scores represent increased frequency and difficulty of stressful events due to the child’s illness. Pairwise comparisons were performed using the Wilcoxon signed-rank test. Multivariate analysis was performed to assess for PSI-SF and PIP predictors.

RESULTS
Of 106 caregivers (84% Caucasian), there were 62 mothers and 40 fathers. There were 68 and 45 responses at 3 and 6 months postoperatively, respectively. Regarding the baseline group, more than 80% were between 20 and 40 years of age and 58% had less than 2 years of college education. The median household income fell in the $45,001–$60,000 bracket. There was no significant difference between median baseline PSI-SF score (65, IQR 51–80) and those at 3 months (p = 0.45) and 6 months (p = 0.82) postoperatively. Both median PIP frequency (89 vs 74, p < 0.01) and difficulty (79 vs 71, p < 0.01) scores were lower at 3 months, although no significant difference was observed at 6 months (frequency: 95 vs 91, p = 0.67; difficulty: 82 vs 80, p = 0.34). Female sex, uninsured status, and open surgery type were all risk factors for higher parental stress.

CONCLUSIONS
Stress levels ranged from normal to clinically significant in the caregivers, with sex, uninsured status, and open repair predicting higher stress. Stress decreased at 3 months postoperatively before increasing at 6 months. Intervention targeting caregiver stress should be explored to maintain lower stress observed at 3 months after surgery.
MODELLING OF SEGMENTS OF ONE-DIMENSIONAL CONTOURS ACCORDING TO THE SPECIFIED CONDITIONS
Authors: Havrylenko Yevhen , Kholodniak Yuliia , Antonova Halyna , Mykhailenko Olena 
Published: June 2022

The formation of one-dimensional contours on the basis on the given conditions is one of the most popular geometric modeling problems. The problem is solved by variative discrete geometric modeling, which assumes the formation of intermediate points for the initial set of condensation points. The discrete model of the curve consists of a point sets, given geometric characteristics and a condensation algorithm.
A discretely presented curve (DPC) is formed by a condensation of the initial point set of an arbitrary configuration in areas on which it is possible to ensure a monotonic change in the values of its characteristics. Monotone plots are joined at special points. Every three consecutive points of the duodenum define an adjacent plane. Four adjacent planes passing through two consecutive points limit the tetrahedron. The chain of consecutive tetrahedrons defined on all segments is the region of the location of the smooth curve of the constant stroke line interpolating the initial point sets. The torsion on the sections of the DPC is estimated by the value of the ratio of the angle between adjacent adjacent planes to the length of the corresponding chord of the accompanying broken line. The point of thickening is assigned inside the tetrahedron of the DPC. As a result of successive condensations, we obtain a continuous bypass of a constant stroke, at each point of which there is a single position of the main trihedron. The point of condensation is assigned in such a way that the values of the torsion in the duodenum points change monotonically. This ensures that the torsion values are regular at the points of the bypass.
The imposition of additional conditions on the DPC formed requires the definition of the corresponding region of a possible solution within the DPC arrangement tetrahedron.