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On the prediction of filtration volume of drilling fluids containing different types of nanoparticles by ELM and PSO-LSSVM based models

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Petroleum 2022年第3期8卷 424-435页

作者： aleksander Lekomtsev Amin Keykhosravi Mehdi Bahari Moghaddam Reza Daneshfar Omid Rezvanjou Department of Oil and Gas Technologies Perm National Research Polytechnic UniversityPerm KraiRussia Faculty of Petroleum and Natural Gas Engineering Sahand University of TechnologyTabrizIran Department of Petroleum Engineering Ahwaz Faculty of Petroleum EngineeringPetroleum University of Technology(PUT)AhwazIran

There is a direct link between the extent of formation damage and the filtration volume of the drilling fluids in hydrocarbon *** filtration volume can be diminished by adding different additives to the drilling ***,nanoparticles have been extensively used for enhancing the filtration characteristics of the drilling ***,there is no reliable model for investigating the influence of this class of additives on the performance of drilling *** in this study,two powerful tools ELM(extreme learning machine)and PSO-LSSVM(particle swarm optimization-least square support vector machine)are applied to determine the effect of various nanoparticles on the filtration *** assessment of the models is carried out by computing the statistical parameters,and it is found that ELM has a greater ability to predict the filtration volumes,while PSO-LSSVM performs satisfactorily *** model predictions and experimental results are in excellent agreement as suggested by the values of root mean squared error(RMSE=0.2459),coefficient of determination(R^(2)=0.999),and mean relative error(MRE=2.028%)for the *** statistical analysis shows that the suggested model can predict the filtration volume with great ***,through sensitivity analysis of the input parameters,it is found that for a specified nanoparticle,the filtration volume is highly influenced by nanoparticle concentration and it is the essential variable for the optimization process.

关键词： Nanoparticles Drilling mud Extreme learning machine Filtration volume Least square support vector machine

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Chemistry and particle size distribution of respirable coal dust in underground mines in Central Eastern Europe

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International Journal of Coal Science & Technology 2022年第1期9卷 200-216页

作者： Pedro Trechera Xavier Querol Robert Lah Diane Johnson aleksander Wrana Ben Williamson Teresa Moreno Instituto de Diagnostico Ambiental Y Estudios del Agua Consejo Superior de Investigaciones Cientificas(IDAEACSIC)C/Jordi Girona 18‑2608034 BarcelonaSpain Department of Natural Resources and Environment Industrial and TIC Engineering(EMIT-UPC)08242 ManresaSpain Premogovnik Velenje d.d Partizanskacesta 783320 VelenjeSlovenia Camborne School of Mines University of ExeterPenrynCornwall TR109FEUK Department of Extraction Technology and Mining Support Central Mining Institute(GIG)40‑166 KatowicePlacGwarkow 1Poland

Despite international efforts to limit worker exposure to coal dust,it continues to impact the health of thousands of miners across *** coal dust has been studied to improve risk models and its control to protect *** size distribution analyses shows that using spraying systems to suppress airborne dusts can reduce particulate matter concentrations and that coals with higher ash yields produce finer *** are marked chemical differences between parent coals and relatively coarse deposited dusts(up to _(500)μm,DD_(500)).Enrichments in Ca,K,Ba,Se,Pb,Cr,Mo,Ni and especially As,Sn,Cu,Zn and Sb in the finest respirable dust fractions could originate from:(i)mechanical machinery wear;(ii)variations in coal mineralogy;(iii)coal fly ash used in shotcrete,and carbonates used to reduce the risk of *** enrichments in Ca in mine dusts are attributed to the use of such concrete,and elevated K to raised levels of phyllosilicate mineral *** concentrations are higher in the parent coal than in the DD_(500),probably due to relatively lower levels of organic *** concentrations of all elements observed in this study remained below occupational exposure limits.

关键词： Coal dust Deposited dust Respirable dust Particle size distribution Dust chemistry PM10 coal dust exposure

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Design and guidance of a multi-active debris removal mission

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Astrodynamics 2023年第4期7卷 383-399页

作者： Minduli C.Wijayatunga(B) Roberto Armellin Harry Holt Laura Pirovano aleksander A.Lidtke Te Pūnaha Atea–Space Institute The University of AucklandAuckland 1010New Zealand Astroscale Japan Inc. 1-16-4-16 KinshiSumida-kuTokyoJapan

Space debris have become exceedingly dangerous over the years as the number of objects in orbit continues to *** debris removal(ADR)missions have gained significant interest as effective means of mitigating the risk of collision between objects in *** study focuses on developing a multi-ADR mission that utilizes controlled reentry and *** mission comprises two spacecraft:a Servicer that brings debris to a low altitude and a Shepherd that rendezvous with the debris to later perform a controlled reentry.A preliminary mission design tool(PMDT)was developed to obtain time and fuel optimal trajectories for the proposed mission while considering the effect of J2,drag,eclipses,and duty *** PMDT can perform such trajectory optimizations for multi-debris missions with computational time under a *** guidance schemes are also studied,taking the PMDT solution as a reference to validate the design methodology and provide guidance solutions to this complex mission profile.

关键词： active debris removal(ADR) trajectory design optimization autonomous guidance low-thrust electric propulsion △u-law guidance Q-law guidance

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Frequency drift rate of solar decameter"drift pair"bursts

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Research in Astronomy and Astrophysics 2017年第9期17卷 101-110页

作者： aleksander Stanislavsky aleksander Konovalenko Yaroslav Volvach Institute of Radio Astronomy Kharkiv 61002Ukraine V.N.Karazin Kharkiv National University Kharkiv 61002Ukraine

This paper deals with the detailed analysis of frequency drift rates of solar ＂drift pair＂（DP） bursts observed from 2015 July 10 to 12 during a type III burst storm. The observations were conducted by the UTR-2 radio telescope at 9-33 MHz with high frequency and time resolution. DPs were recorded drifting from higher to lower frequencies （forward DPs） as well as from lower to higher ones （reverse DPs）. Patterns on their dynamic spectrum had various inclines and occupied different bandwidths. The frequency drift rate versus frequency dependence of these bursts has been studied. The fitting model to describe the peak evolution of these bursts in the frequency-time plane is presented. The relationship between DPs and type III solar bursts is discussed.

关键词： Sun: corona -- Sun radio radiation -- methods observational -- techniques spectroscopic

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Some Results Connected with the Class Number Problem in Real Quadratic Fields

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Acta Mathematica Sinica,English Series 2005年第5期21卷 1107-1112页

作者： aleksander GRYTCZUK Jaroslaw GRYTCZUK Faculty of Mathematics.Computer Science and Econometrics University of Zielona Gora.65 516 Zielona Gora.Poland Institute

We investigate arithmetic properties of certain subsets of square-free positive integers and obtain in this way some results concerning the class number h（d） of the real quadratic field Q（√d）. In particular, we give a new proof of the result of Hasse, asserting that in this case h（d） = 1 is possible only if d is of the form p, 2q or qr. where p.q. r are primes and q≡r≡3（mod 4）.

关键词： The class number Real quadratic field

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An Industry 4.0 Approach to the 3D Printing of Composite Materials

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Engineering 2019年第4期5卷 621-623页

作者： Bronwyn Fox aleksander Subic Swinburne Research Swinburne University of TechnologyHawthornVIC 3122Australia

Carbon fiber composites are lightweight,high-strength engineered materials that can be 10 times stronger than steel and eight times stronger than aluminum at a fraction of the weight of these *** manufacture has become a growth area for Australia in the past decade,leading to new export ***,in order to maintain this lead and momentum,the key challenge to overcome is to increase the rate and lower the cost of *** can only be achieved by using automation and digitalization to reduce slow and labor-intensive manual processes.

关键词： materials. composites overcome

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Numerical modelling of the hybrid rocket engine performance

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Propulsion and Power Research 2021年第1期10卷 15-22页

作者： Marian Gieras aleksander Gorgeri a Institute of Heat Engineering Warsaw University of TechnologyWarsaw00-665Poland Łukasiewicz Research Network e Institute of Aviation Warsaw02-256Poland

The purpose of this paper is to present method of the numerical modeling of the hybrid rocket engine's work as a tool for designing engines of this *** model is intended as an accurate and simple to use development tool for use in preliminary design stages of hybrid rocket engines,improving the effectiveness and quality of this *** assumptions underlying the use of a model are presented,together with an analysis of past work in this *** of an extensive experimental campaign are presented and compared with the results of numerical modelling in order to calibrate the proposed model and evaluate its ***eter variation and optimization were conducted,proving functionality of the ***sented numerical calculations show that the adopted approach to reduce the analysis time and complexity was *** method of numerical calculation of hybrid engine working parameters combines aspects of accuracy and simplicity at the early design stage to avoid timeconsuming and costly changes in subsequent detailed stages of design.

关键词： Hybrid rocket engine Combustion Multi-phase flow Regression Specific impulse

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Sperm chromatin structure assay （SCSA）： a tool in diagnosis and treatment of infertility

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Asian Journal of Andrology 2011年第1期13卷 69-75页

作者： Mona Bungum Leif Bungum aleksander giwerc.an Reproductive Medicine Centre （RMC） Skane University Hospital SE - 205 02 Maimo Sweden

Diagnosis of male infertility has mainly been based on the World Health Organization （WHO） manual-based semen parameter＇s concentration, motility and morphology. It has, however, become apparent that none of these parameters are reliable markers for evaluation of the fertility potential of a couple. A search for better markers has led to an increased focus on sperm chromatin integrity testing in fertility work-up and assisted reproductive techniques. During the last couple of decades, numerous sperm DNA integrity tests have been developed. These are claimed to be characterized by a lower intraindividual variation, less intralaboratory and interlaboratory variation and thus less subjective than the conventional sperm analysis. However, not all the sperm chromatin integrity tests have yet been shown to be of clinical value. So far, the test that has been found to have the most stable clinical threshold values in relation to fertility is the sperm chromatin structure assay （SCSA）, a flow cytometric test that measures the susceptibility of sperm DNA to acid-induced DNA denaturation in situ. Sperm DNA fragmentation as measured by SCSA has shown to be an independent predictor of successful pregnancy in first pregnancy planners as well as in couples undergoing intrauterine insemination, and can be used as a tool in investigation, counseling and treatment of involuntary childlessness. More conflicting data exist regarding the role of sperm DNA fragmentation in relation to fertilization, pre-embryo development and pregnancy outcome in in vitro fertilization and intracytoplasmic sperm injection （ICSI）.

关键词： assisted reproductive techniques infertility sperm chromatin structure assay sperm DNA

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Environmental xenobiotics and male reproductive health

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Asian Journal of Andrology 2014年第1期16卷 3-4页

作者： Jens Peter Bonde aleksander giwerc.an Department of Occupational and Environmental Medicine Frederiksberg and Bispebjerg Hospital University of Copenhagen Denmark Reproductive Medicine Centre Skne University Hospital Maim6 Sweden.

Lessons from the occupational arena fdemonstrate the potential of industrial 4chemicals to damage human testicular function. An important but still unresolved question is whether low-level xenobiotic exposure of the general population poses a hazard. In this volume of the Asian Journal of Andrology, this issue is addressed by a series of reviews on xenobiotic exposure profiles, possible biological mechanisms, research methods and knowledge on impact of specific exposures. Interdisciplinary research fields as gene-environment interaction and male-mediated developmental toxicity is also addressed. Papers are cross-linked by answers to questions mutually put forward by the authors.

关键词： xenobiotics chemicals occupational

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Tailoring electrical conductivity of two dimensional nanomaterials using plasma for edge electronics: A mini review

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Frontiers of Chemical Science and Engineering 2019年第3期13卷 427-443页

作者： Aswathy Vasudevan Vasyl Shvalya aleksander Zidansek Uros Cvelbar Jozef Stefan Institute 1000 LjubljanaSlovenia Jozef Stefan International Postgraduate School 1000 LjubljanaSlovenia Faculty of Natural Sciences and Mathematics University of Maribor2000 MariborSlovenia

Since graphene has been discovered, twodimensional nanomaterials have attracted attention due to their promising tunable electronic properties. The possibility of tailoring electrical conductivity at the atomic level allows creating new prospective 2D structures for energy harvesting and sensing-related applications. In this respect, one of the most successful way to manipulate the physical properties of the aforementioned materials is related to the surface modification techniques employing plasma. Moreover, plasma-gaseous chemical treatment can provide a controlled change in the bandgap, increase sensitivity and significantly improve the structural stability of material to the environment as well. This review deals with recent advances in the modification of 2D carbon nanostructures for novel ‘edge’ electronics using plasma technology and processes.

关键词： graphene edge electronics 2D nanomaterials plasma electrical conductivity

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