bluuebunny/crossref_metadata_2025 huggingface dataset:
Prolonged Activated Partial Thromboplastin Time after Successful Resuscitation from Cardiac Arrest is Associated with Unfavorable Neurologic Outcome
Authors: Schriefl Christoph , Schoergenhofer Christian , Grafeneder Juergen , Poppe Michael , Clodi Christian , Mueller Matthias , Ettl Florian , Jilma Bernd , Wallmueller Pia , Buchtele Nina , Weikert Constantin , Losert Heidrun , Holzer Michael , Sterz Fritz , Schwameis Michael
Published: November 2020

Coagulation abnormalities after successful resuscitation from cardiac arrest may be associated with unfavorable neurologic outcome. We investigated a potential association of activated partial thromboplastin time (aPTT) with neurologic outcome in adult cardiac arrest survivors. Therefore, we included all adults ≥18 years of age who suffered a nontraumatic cardiac arrest and had achieved return of spontaneous circulation between January 2013 and December 2018. Patients receiving anticoagulants or thrombolytic therapy and those subjected to extracorporeal membrane oxygenation support were excluded. Routine blood sampling was performed on admission as soon as a vascular access was available. The primary outcome was 30-day neurologic function, assessed by the Cerebral Performance Category scale (3–5 = unfavorable neurologic function). Multivariable regression was used to assess associations between normal (≤41 seconds) and prolonged (>41 seconds) aPTT on admission (exposure) and the primary outcome. Results are given as odds ratio (OR) with 95% confidence intervals (95% CIs). Out of 1,591 cardiac arrest patients treated between 2013 and 2018, 360 patients (32% female; median age: 60 years [interquartile range: 48–70]) were eligible for analysis. A total of 263 patients (73%) had unfavorable neurologic function at day 30. aPTT prolongation >41 seconds was associated with a 190% increase in crude OR of unfavorable neurologic function (crude OR: 2.89; 95% CI: 1.78–4.68, p < 0.001) and with more than double the odds after adjustment for traditional risk factors (adjusted OR: 2.01; 95% CI: 1.13–3.60, p = 0.018). In conclusion, aPTT prolongation on admission is associated with unfavorable neurologic outcome after successful resuscitation from cardiac arrest.
CMOS-compatible all-dielectric metalens for improving pixel photodetector arrays
Authors: Mikheeva E. , Claude J.-B. , Salomoni M. , Wenger J. , Lumeau J. , Abdeddaim R. , Ficorella A. , Gola A. , Paternoster G. , Paganoni M. , Auffray E. , Lecoq P. , Enoch S.
Published: November 2020

Metasurfaces and, in particular, metalenses have attracted large interest and enabled various applications in the near-infrared and THz regions of the spectrum. However, the metalens design in the visible range stays quite challenging due to the smaller nanostructuring scale and the limited choice of lossless CMOS-compatible materials. We develop a simple yet efficient design of a polarization-independent, broadband metalens suitable for many CMOS-compatible fabrication techniques and materials and implement it for the visible spectral range using niobium pentoxide (Nb2O5). The produced metalens demonstrates high transmittance and focusing ability as well as a large depth of focus, which makes it a promising solution for a new generation of silicon photomultiplier photodetectors with reduced fill factor impact on the performance and reduced electron–hole generation regions, which altogether potentially leads to improved photodetection efficiency and other characteristics.
Experimental investigation of internal two-phase flow structures and dynamics of quasi-stable sheet cavitation by fast synchrotron x-ray imaging
Authors: Zhang Guangjian , Khlifa Ilyass , Fezzaa Kamel , Ge Mingming , Coutier-Delgosha Olivier
Published: November 2020

The quasi-stable sheet cavitation produced in a small Venturi channel is investigated using a fast synchrotron x-ray imaging technique aided with conventional high speed photography. The use of x rays instead of visible light solves cavitation opacity related issues, and x-ray phase contrast-based edge enhancement enables high-definition visualization of the internal two-phase morphology. The simultaneous acquisition of time-resolved velocity and void fraction fields through post-processing of the recorded x-ray images reveals, for the first time, the complex diphasic flow structures inside the sheet cavity, which is essentially divided into six characteristic parts. Distinct from the current mainstream view, the globally steady sheet cavitation is found to be characterized by a weak but constantly existing re-entrant flow that can penetrate the entire cavity. The turbulent velocity fluctuations inside the sheet cavity are also investigated. The turbulence level in the reverse flow region is observed to be as low as in the outer main flow, demonstrating the relatively steady status of the re-entrant flow. Unlike the streamwise and cross-stream fluctuations, the shear stress appears to be weakly correlated with the velocity gradient. The collapse of the vapor phase and the vaporization at the upstream cavity interface are found to be the primary causes of shear stress intensification.
High-efficiency gate-defined quantum dot to single mode fiber interface assisted by a photonic crystal cavity
Authors: Wu K. , Marzban B. , Descamps T. , Bluhm H. , Merget F. , Witzens J.
Published: November 2020

Efficiently interfacing photonic with semiconductor qubits plays an important role in future quantum communication applications. In this paper, we model a photon to exciton interface based on an optically active gate-defined quantum dot (OAQD) embedded in a carefully designed photonic crystal cavity constraining its emission profile via the Purcell effect while maintaining a low enough quality factor to allow for electrical tuning of the emission wavelength. By matching the in-plane k-vector of a cavity mode and the reciprocal lattice constant of the photonic crystal, vertical emission is obtained. A back-reflection mirror located below the cavity and integrated as part of an already predefined process flow allows for not only the increasing of the light extraction efficiency but also the tailoring of the extracted beam profile to match that of a single mode fiber. We numerically show that a photon emitted by the OAQD can be coupled to the targeted free-space Gaussian beam with a probability above 50%, limited by electrode absorption. Further efficiency improvement up to 90% is possible by using indium tin oxide instead of gold as a gate material.
Diffusion and chemical interaction of hydroxyl generated from photodissociation of water vapor in the temperature range in 294 K–891 K in helium flow
Authors: Shao Jun , Li GuoHua , Ye JingFeng , Zhang ZhenRong , Zhang Zhen , Hu ZhiYun , Wang Sheng , Li JingYin
Published: November 2020

This paper summarizes the direct observation of tagged hydroxyl within 200 µs after its formation in the temperature range of 294 K–891 K. We estimate the time and temperature frame of the coexistence of chemical reactions and diffusion based on analysis of the behavior of the tagging fluorescence spot of photodissociation hydroxyl. The reasons for the existence of chemical reactions and interactions between chemical reactions and diffusion are then analyzed. Theoretical and experimental identification of this frame can be explored for non-contact spectral measurements based on hydroxyl in a general flow field.
Evaluation of electrical conductivity and anisotropy in muscle tissues using conductivity tensor imaging (CTI)
Authors: Choi Bup Kyung , Katoch Nitish , Ko In Ok , Park Ji Ae , Kim Jin Woong , Kim Hyung Joong , Woo Eung Je
Published: November 2020

Low-frequency conductivity of an anisotropic tissue is associated with its cellular structure. Imaging of the conductivity tensor inside the human body could prove invaluable to analyses of interactions between electromagnetic fields and biological systems, such as predictions of current pathways during electrical stimulation. Since the muscle is the most abundant anisotropic tissue in the human body, in vitro and in vivo muscle conductivity tensor assessment has been attempted. In this study, we conducted phantom imaging of biological tissues using conductivity tensor imaging (CTI) to validate its in vivo usefulness. We constructed phantoms using bovine and/or porcine muscles and performed a CTI experiment using MRI. High-frequency conductivity was first obtained using B1 mapping with a multi-echo spin-echo pulse sequence. Information about the cellular space was obtained with a multi-b diffusion tensor imaging sequence. We combined the data from these separate scans to reconstruct the conductivity tensor images of the phantoms. The low-frequency and high-frequency conductivities of the muscle tissues in the phantoms were compared with the corresponding values measured by an impedance analyzer. The anisotropy of each muscle tissue was quantified as an anisotropy ratio (AR), defined as the ratio of the eigenvalues of a conductivity tensor along the longitudinal direction to those along the transversal directions. The isotropic conductivity and conductivity tensor in bovine muscles were less than those of porcine muscles. However, the anisotropy was stronger in bovine muscles based on the AR values by fiber directions. Current CTI is a promising noninvasive tool for evaluation of the muscle microstructure.
Rectal douching among men who have sex with men in six cities in China: a cross-sectional study
Authors: Li Peiyang , Yuan Tanwei , Wang Zhenyu , Huang Ruonan , Meng Xiaojun , Zhang Kechun , Wang Guanghui , Zhou Yepeng , Luo Danyang , Wang Ying , Cai Yong , Zou Huachun
Published: November 2020

Background
Rectal douching, which is a common practice among men who have sex men (MSM) as a preparation for anal sex, may potentially increase the risk of HIV infection. However, little is known about the practice of rectal douching among Chinese MSM. This study investigated the characteristics of rectal douching and factors associated with rectal douching. Methods: Between January and March 2019, MSM aged ≥18 years in six cities in China were recruited to the study. Participants were asked to complete a self-administered online questionnaire. Chi-squared tests and multivariable logistic regression were used to examine factors associated with rectal douching by calculating odds ratios (ORs) and 95% confidence intervals (CIs). Results: Of 485 MSM in this study, 278 (57.3%) practiced rectal douching in the preceding 6 months. The most common reasons for douching before and after anal sex were hygiene/cleanliness (78.6% and 66.1% respectively) and HIV/STI prevention (8.5% and 17.4% respectively). The most used enemas and equipment before and after anal sex were tap water (73.5% and 70.2% respectively) and showerhead hoses (76.1% and 75.2% respectively). Men who engaged in both insertive and receptive anal sex (OR 8.84; 95% CI 4.52–17.30), exclusively receptive anal sex (OR 6.56; 95% CI 3.55–12.13), condom-less anal intercourse (OR 1.64; 95% CI 1.03–2.63) and anal sex after alcohol use (OR 1.54; 95% CI 1.00–2.35) were more likely to perform douching. Conclusion: Rectal douching is common in MSM, some of whom may not realise the potential risks associated with douching. The co-occurrence of douching and other high-risk behaviours would make MSM more vulnerable to HIV. Health education aimed at informing MSM of the potential risks and addressing the high prevalence of douching are urgently needed.
Analysis of genomic distributions of SARS-CoV-2 reveals a dominant strain type with strong allelic associations
Authors: Yang Hsin-Chou , Chen Chun-houh , Wang Jen-Hung , Liao Hsiao-Chi , Yang Chih-Ting , Chen Chia-Wei , Lin Yin-Chun , Kao Chiun-How , Lu Mei-Yeh Jade , Liao James C.
Published: November 2020

Significance

In this study, we discovered that the genome of SARS-CoV-2 to date can be classified in six major types characterized by 14 signature single nucleotide variations (SNVs). In particular, type VI, that was first reported in China and spread to different countries, has become the major type (more than 95% among data collected after mid-May 2020). The signature SNVs for this strain type, C241T (5′UTR), C3037T (nsp3 F924F), C14408T (nsp12 P4715L), and A23403G (S protein D614G), exhibit high pairwise allelic associations, and the haplotype 241T-3037T-14408T-23403G has the highest frequency. Understanding nucleotide variations in the SARS-CoV-2 genome will provide useful insight for the developmental history of the pandemic, and even the disease management, if the biological significance is understood.
Stability estimates for the relativistic Schrödinger equation from partial boundary data
Authors: Senapati Soumen
Published: November 2020

We derive stability estimates for the determination of time-dependent vector and scalar potentials in the relativistic Schrödinger equation from partial boundary data. For the case of space dimensions at least 3, we obtain log–log stability estimates for the determination of vector potentials (modulo gauge equivalence) and log–log–log stability estimates for the determination of scalar potentials from partial boundary data assuming suitable a priori bounds on these potentials.
Synthesis mechanism of cuprous oxide nanoparticles by atmospheric-pressure plasma electrolysis
Authors: Liu Jiandi , Shirai Naoki , Sasaki Koichi
Published: November 2020

The synthesis mechanism of cuprous oxide (Cu2O) nanoparticles by atmospheric-pressure plasma electrolysis was investigated experimentally. In the plasma electrolysis system, a helium plasma in contact with an NaCl electrolyte was used as the cathode, while a copper plate which was partly immersed into the electrolyte was used as the counter electrode. X-ray powder diffraction, field-emission scanning electron microscopy, and transmission electron microscopy were used for characterizing the synthesized products. The results indicate that the Cl− concentration and the pH value of the electrolyte dominate the synthesis of Cu2O nanoparticles. The reaction between CuCl

2
−

produced via the anodic dissolution of Cu and OH− produced by plasma irradiation is responsible for the formation of Cu2O. The comparison between the plasma and conventional electrolysis has also been carried out, since the anodic dissolution of the Cu plate and the production of OH− are also available in the conventional electrolysis. As a result, we also observed the synthesis of Cu2O nanoparticles by the conventional electrolysis. However, we observed the differences between the plasma and conventional electrolysis in the synthesis rate, the minimum NaCl concentration, and the size and the shape of synthesized nanoparticles.
Numerical study of molten metal melt pool behaviour during conduction-mode laser spot melting
Authors: Ebrahimi Amin , Kleijn Chris R , Richardson Ian M
Published: November 2020

Molten metal melt pools are characterised by highly non-linear responses, which are very sensitive to imposed boundary conditions. Temporal and spatial variations in the energy flux distribution are often neglected in numerical simulations of melt pool behaviour. Additionally, thermo-physical properties of materials are commonly changed to achieve agreement between predicted melt-pool shape and experimental post-solidification macrograph. Focusing on laser spot melting in conduction mode, we investigated the influence of dynamically adjusted energy flux distribution and changing thermo-physical material properties on melt pool oscillatory behaviour using both deformable and non-deformable assumptions for the gas-metal interface. Our results demonstrate that adjusting the absorbed energy flux affects the oscillatory fluid flow behaviour in the melt pool and consequently the predicted melt-pool shape and size. We also show that changing the thermo-physical material properties artificially or using a non-deformable surface assumption lead to significant differences in melt pool oscillatory behaviour compared to the cases in which these assumptions are not made.
Automatic detection and segmentation of multiple brain metastases on magnetic resonance image using asymmetric UNet architecture
Authors: Cao Yufeng , Vassantachart April , Ye Jason C , Yu Cheng , Ruan Dan , Sheng Ke , Lao Yi , Shen Zhilei Liu , Balik Salim , Bian Shelly , Zada Gabriel , Shiu Almon , Chang Eric L , Yang Wensha
Published: November 2020

Detection of brain metastases is a paramount task in cancer management due both to the number of high-risk patients and the difficulty of achieving consistent detection. In this study, we aim to improve the accuracy of automated brain metastasis (BM) detection methods using a novel asymmetric UNet (asym-UNet) architecture. An end-to-end asymmetric 3D-UNet architecture, with two down-sampling arms and one up-sampling arm, was constructed to capture the imaging features. The two down-sampling arms were trained using two different kernels (3 × 3 × 3 and 1 × 1 × 3, respectively) with the kernel (1 × 1 × 3) dominating the learning. As a comparison, vanilla single 3D UNets were trained with different kernels and evaluated using the same datasets. Voxel-based Dice similarity coefficient (DSCv), sensitivity (S
v), precision (P
v), BM-based sensitivity (S
BM), and false detection rate (F
BM) were used to evaluate model performance. Contrast-enhanced T1 MR images from 195 patients with a total of 1034 BMs were solicited from our institutional stereotactic radiosurgery database. The patient cohort was split into training (160 patients, 809 lesions), validation (20 patients, 136 lesions), and testing (15 patients, 89 lesions) datasets. The lesions in the testing dataset were further divided into two subgroups based on the diameters (small S = 1–10 mm, large L = 11–26 mm). In the testing dataset, there were 72 and 17 BMs in the S and L sub-groups, respectively. Among all trained networks, asym-UNet achieved the highest DSCv of 0.84 and lowest F
BM of 0.24. Although vanilla 3D-UNet with a single 1 × 1 × 3 kernel achieved the highest sensitivities for the S group, it resulted in the lowest precision and highest false detection rate. Asym-UNet was shown to balance sensitivity and false detection rate as well as keep the segmentation accuracy high. The novel asym-UNet segmentation network showed overall competitive segmentation performance and more pronounced improvement in hard-to-detect small BMs comparing to the vanilla single 3D UNet.
Generalized exceptional quantum walk search
Authors: Li Meng , Shang Yun
Published: November 2020

We mainly study exceptional configuration for coined quantum walk search. For searching on a two-dimensional grid by AKR algorithm, we find some new classes of exceptional configurations that cannot be found by the AKR algorithm effectively and the known diagonal configuration can be regarded as its special case. Meanwhile, we give two modified quantum walk models that can improve the success probability in the exceptional configurations by numerical simulation. Furthermore, we introduce the concept of generalized exceptional configuration and consider search by quantum walk on a cycle with Grover coin. We find that the most common coin combination model (G, −), where G is a Grover diffusion transformation, is a generalized exceptional configuration when just searching one marked vertex on the cycle. In the end, we find generalized exceptional configuration has a different evolution of quantum coherence from exceptional configuration. These extend largely the range of exceptional configuration of quantum walk search in some sense.
Comparative study of pulsed laser diode end-pumped thulium-doped 2-μm Q-switched lasers*
Authors: Wen Ya , Fan Zhen , Shang Lin-Hao , Jin Guang-Yong , Chao Wang , Chen Xin-Yu , Wu Chun-Ting
Published: November 2020

We report pulsed laser diode (LD) end-pumped acoustic Q-switched Tm:YAG laser, Tm:LuAG laser, and Tm:LuYAG laser and the physical properties and spectra of Tm:YAG, Tm:LuAG, and Tm:LuYAG are analyzed. The Tm:LuYAG laser is pumped by 785-nm and 788-nm pulses separately, and is compared with Tm:YAG laser. Different output energy values and output wavelengths of Tm:LuAYG lasers pumped by LDs with different wavelengths are obtained and compared with each other. When the repetition frequency is 100 Hz, the pulsed Tm:YAG laser has single pulse energy of 15.9 mJ, pulse width of 126.7 ns, and the center wavelength of 2013.36 nm, and the pulsed Tm:LuAG laser possesses single pulse energy of 11.8 mJ, pulse width of 252.4 ns, and the center wavelength of 2023.65 nm, and the pulsed Tm:LuYAG laser output energy values are 12.32 mJ and 12.25 mJ with the slope efficiencies of 12.5% and 11.85%, the center wavelengths of 2017.89 nm and 2027.11 nm, respectively, while the pump sources are 785-nm and 788-nm pulsed LDs, respectively.
Molecular photoelectron momentum and angular distributions of N2 molecules by ultrashort attosecond laser pulses*
Authors: Zhang Si-Qi , Zhen Qi , Yang Zhi-Jie , Zhang Jun , Liu Ai-Hua , Yuan Kai-Jun , Liu Xue-Shen , Guo Jing
Published: November 2020

The ultrafast photoionization dynamics of N2 molecules by x-ray/XUV laser pulses is investigated. The molecular frame photoelectron momentum distributions (MF-PMDs) and the molecular frame photoelectron angular distributions (MF-PADs) are obtained by numerically solving 2D time-dependent Schrödinger equations within the single-electron approximation (SEA) frame. The results show that the molecular photoionization diffraction appears in 5 nm laser fields. However, when the laser wavelength is 30 nm, the molecular photoionization diffraction disappears and the MF-PMDs show four-lobe pattern. The ultrafast photoionization model can be employed to describe the MF-PMDs and MF-PADs of N2 molecules.
Nonlinear spectroscopy of three-photon excitation of cesium Rydberg atoms in vapor cell*
Authors: Fan Jiabei , He Yunhui , Jiao Yuechun , Hao Liping , Zhao Jianming , Jia Suotang
Published: November 2020

We present nonlinear spectra of four-level ladder cesium atoms employing 6S
1/2 → 6P
3/2→ 7S
1/2 → 30P
3/2 scheme of a room temperature vapor cell. A coupling laser drives Rydberg transition, a dressing laser couples two intermediate levels, and a probe laser optically probes the nonlinear spectra via electromagnetically induced transparency (EIT). Nonlinear spectra are detected as a function of coupling laser frequency. The observed spectra exhibit an enhanced absorption (EA) signal at coupling laser resonance to Rydberg transition and enhanced transmission (ET) signals at detunings to the transition. We define the enhanced absorption (transmission) strength, H
EA (H
ET), and distance between two ET peaks, γ
ET, to describe the spectral feature of the four-level atoms. The enhanced absorption signal H
EA is found to have a maximum value when we vary the dressing laser Rabi frequency Ω
d, corresponding Rabi frequency is defined as a separatrix point, Ω
dSe
. The values of Ω
dSe
and further η = Ω
dSe
/Ω
c are found to depend on the probe and coupling Rabi frequency but not the atomic density. Based on Ω
dSe
, the spectra can be separated into two regimes, weak and strong dressing ranges, Ω
d ≲ Ω
dSe
and Ω
d ≳ Ω
dSe
, respectively. The spectroscopies display different features at these two regimes. A four-level theoretical model is developed that agrees well with the experimental results in terms of the probe-beam absorption behavior of Rabi frequency-dependent dressed states.
Axial acoustic radiation force on an elastic spherical shell near an impedance boundary for zero-order quasi-Bessel–Gauss beam*
Authors: Zang Yu-Chen , Lin Wei-Jun , Su Chang , Wu Peng-Fei
Published: November 2020

Shell structures have increasingly widespread applications in biomedical ultrasound fields such as contrast agents and drug delivery, which requires the precise prediction of the acoustic radiation force under various circumstances to improve the system efficiency. The acoustic radiation force exerted by a zero-order quasi-Bessel–Gauss beam on an elastic spherical shell near an impedance boundary is theoretically and numerically studied in this study. By means of the finite series method and the image theory, a zero-order quasi-Bessel–Gauss beam is expanded in terms of spherical harmonic functions, and the exact solution of the acoustic radiation force is derived based on the acoustic scattering theory. The acoustic radiation force function, which represents the radiation force per unit energy density and per unit cross-sectional surface, is especially investigated. Some simulated results for a polymethyl methacrylate shell and an aluminum shell are provided to illustrate the behavior of acoustic radiation force in this case. The simulated results show the oscillatory property and the negative radiation force caused by the impedance boundary. An appropriate relative thickness of the shell can generate sharp peaks for a polymethyl methacrylate shell. Strong radiation force can be obtained at small half-cone angles and the beam waist only affects the results at high frequencies. Considering that the quasi-Bessel–Gauss beam possesses both the energy focusing property and the non-diffracting advantage, this study is expected to be useful in the development of acoustic tweezers, contrast agent micro-shells, and drug delivery applications.
Analysis of strong refractive effect within 11Li projectile structure
Authors: Behairy Kassem O. , El-Azab Farid M. , Ibraheem Awad A. , Ramadan Ola , Anwar M.
Published: November 2020

In the context of the double folding optical model, the strong refractive effect for elastic scattering of 11Li + 12C and 11Li + 28Si systems at incident energies of 29, 50, and 60 MeV/n is studied. Real folded potentials are generated based on a variety of nucleon-nucleon interactions with the suggested density distributions for the halo structure of 11Li nuclei. The rearrangement term (RT) of the extended realistic density dependent CDM3Y6 effective interaction is considered. The imaginary potential was taken in the traditional standard Woods-Saxon form. Satisfactory results for the calculated potentials are obtained, with a slight effect of the RT in CDM3Y6 potential. Successful reproduction with a normalization factor close to one for the observed angular distributions of the elastic scattering differential cross section has been achieved using the derived potentials. The obtained reaction cross-section is studied as a guide by extrapolating our calculations and previous results.
Neutron star cooling and GW170817 constraint within quark-meson coupling models *
Authors: Lourenço Odilon , Lenzi César H. , Dutra Mariana , Frederico Tobias , Bhuyan M. , Negreiros Rodrigo , Flores César V. , Grams Guilherme , Menezes Débora P.
Published: November 2020

In the present work, we used five different versions of the quark-meson coupling (QMC) model to compute astrophysical quantities related to the GW170817 event and the neutron star cooling process. Two of the models are based on the original bag potential structure and three versions consider a harmonic oscillator potential to confine quarks. The bag-like models also incorporate the pasta phase used to describe the inner crust of neutron stars. With a simple method studied in the present work, we show that the pasta phase does not play a significant role. Moreover, the QMC model that satisfies the GW170817 constraints with the lowest slope of the symmetry energy exhibits a cooling profile compatible with observational data.
Non-stationary mass transfer of oil-water mixture in reservoirs with a system of horizontal wells
Authors: Zhizhimontov I N , Zemenkov Yu D , Shabarov A B
Published: November 2020

The paper presents a physical and mathematical model of quasi-three-dimensional non-stationary filtration of a water-oil mixture in a system of horizontal wells and the corresponding numerical calculation method. Based on them, a computer program was created, designed to solve a number of scientific and production problems. The developed model and program are aimed at theoretical and numerical study of the processes of mass transfer of the oil-water mixture in the field of analysis, maintenance and development of natural formations with high-viscosity oil deposits. The results of numerical experiments for calculating the two-phase flow of an incompressible fluid in a reservoir are given as an example of a real field, located in the north of Western Siberia. The paper proposes an approach to discretization of the computational domain, based on the construction of a dynamic computational grid in a natural semi-fixed coordinate system. For the first time, the problem of calculating two-phase mass transfer using a semi-fixed natural grid and an analytical expression for the flow rates of phases in current streams of a found shape has been solved. Based on the proposed model, calculation and parametric studies of various modes of field development with a system of parallel horizontal wells were performed.
Complex thermophysical modeling of processes in the foundation soil of oil pipelines in the Arctic and offshore conditions
Authors: Golik V V , Zemenkov Yu D , Shagbanov I F
Published: November 2020

The paper presents the results describing the mathematical model in operation and testing methodology aimed at heat engineering calculations needed to do for multilayer oil pipelines. A section of the pipeline running under difficult geological conditions is under simulation. The methodology aimed at calculating the thermal processes and its results are described. The simulation was carried out by using some insulating materials with a constant internal diameter of the pipeline and a pumping mode. The simulation was carried out with the universal software system of end-element modeling – ANSYS and with a module developed by the authors for TPS thermotechnical calculations.
Studying quality of diagnosing rolling stock at service enterprises of automobile transport
Authors: Krasovsky V N , Krasovskaya N I , Sycheva A V
Published: November 2020

The article focuses on one of the car service market components being a car diagnostic system and, in particular, on the effectiveness of the activities of diagnostic operators. The objective of this study was an experimental assessment of the effectiveness of the proposed methods for improving the training of diagnostic operators. The results of testing hypotheses on the correct diagnosis by a group of specialists on the technical condition of passenger car engines are presented.
A comprehensive analysis of the properties of reservoir rocks to determine the productive oil horizons
Authors: Klyuev R V , Bosikov I I , Revazov V Ch , Krysanov K S , Dzeranov B V
Published: November 2020

The purpose of the research is to study the reservoir and filtration properties of reservoir rocks of the Aptian horizon of formation No. 1 within the Kovylnoye field. The initial data were reservoir-filtration and geological-geophysical parameters within the exposed rocks of the reservoirs of the Aptian horizon of formation No. 1, for wells No. 1 and No. 2, which were drilled at the search and evaluation stage of work: porosity coefficient, permeability coefficient, rock resistivity, oil-saturated thickness. High values of effective porosity, permeability, and oil and gas saturation are found in biomorphic, organogenic, and clastic carbonate rocks where the void space has not been subjected to secondary changes (salt deposits), resulting in reservoirs characterized by low capacitance and filtration properties. Analysis of carbonate reservoirs gives values of permeability up to 0.3-1 mm2 and porosity of 20-35 %. Rocks are lumpy, loose, weakly cemented with cement content up to 10%. Their initial water saturation in the oil deposit does not exceed 5-20 %. The research has shown the effectiveness of conducting a comprehensive analysis of reservoir rock properties to determine the oil and gas content of the site.
Main aspects of the oil industry within the sustainable development concept
Authors: Fomenko N , Mohammed Jasim Hamad Al Mashkhadani
Published: November 2020

The main aspects of the industry development within the concept of sustainable development are considered in the article by the example of the oil industry. Sustainable development means the collaboration of three principal components, including ecology, society, economy. According to the carried-out analysis, the field of application and the stages of development of this concept are pointed out. The authors defined the economic, social, technology, ecological and political factors, influencing the development of the oil and gas industry. Thus, the application of the sustainable development concept in the oil industry will allow supporting the balance between the economy and the environment without causing damage to the environment, keeping resource base and providing stable improvement of quality of the population life.
Issues of ensuring the design durability of reinforced concrete supports of the main pipelines of oil refineries
Authors: Fedorov P A , Abdullin M M , Fatykhova A M , Fattakhov M M
Published: November 2020

The aggressive environment of oil refineries contributes to increased corrosion of reinforced concrete supports of trunk pipelines. This is primarily due to the increased concentration of acid gases. The article presents results of the analysis of the gas-air environment of an oil refinery and its impact on primary support measures. It was established that when using typical reinforced concrete supports made from B15 W2 concrete, the protective layer with a thickness of 15 mm becomes neutralized 3-6 years after the operation. To ensure continuous 25-year operation, it is necessary to increase thickness of the protective layer to 35 mm. To increase the durability of the structure, it is proposed to replace steel reinforcement with “metal-fiberglass” or hybrid fiberglass one.
Temporary and operational transport roads in construction of transfer linear structures and their scientific and technical support
Authors: Kortiev L I , Klyuev R V , Totchiev F G , Vaneev S D , Babunska N I
Published: November 2020

Due to the economic and technical progress of countries and regions in Europe, the necessary and possible transport communications, power lines (power lines), various pipelines and other linear structures were laid through the Alpine Mountains. The Caucasian Mountains in this part are strongly lagging behind. The railway crosses the Main Caucasian Ridge (MCR) only in the western part up to the Black Sea coast, and the automobile road is in the Central part through the Cross Pass along the Georgian Military Highway and the Roksky Pass along the Military Ossetian Road. The Gas pipelines and power lines were laid in the same areas. At the beginning of the 11th century, the Dzuarikau - Tskhinval pipeline was laid to provide gas to the population of South Ossetia. In the peak position this gas pipeline is the highest one on a global scale being of a particular organizational interest. Of the same interest is the construction of a road through the Roksky Pass, hereinafter referred to as Transkam. Organizationally, these two linear structures had to be laid on the automobile road as a temporary one and a technologically advanced soil and gravel road on the gas pipeline at an absolute height of more than 3,000 meters. These roads have important social, economic, agricultural and strategic importance which is considered in this article.
Modern technologies of project management and implementation in the construction industry
Authors: Ermakov A A , Korkishko A N , Smirnov S A , Shapovalov A S
Published: November 2020

The article considers the technology of management and implementation of project activities, from the perspective of project management in the field of innovation and multifunctionality of work in the field of construction and production. The current existing approaches to project management in various manufacturing fields and also such special tools as the construction extension of project management standards have been examined. As follows from the analysis, the main features of the considered standards are highlighted and conclusions were reached on the necessity to use modern technologies in project management.
Analysis of the development of global energy production and consumption by fuel type in various regions of the world
Authors: Shalaeva D S , Kukartseva O I , Tynchenko V S , Kukartsev V V , Aponasenko S V , Stepanova E V
Published: November 2020

This article is devoted to the analysis of the geographical structure of the world energy industry. The article analyzes trends in global energy production and consumption from 1990 to 2018. Statistical indicators of energy production and consumption are also considered. The study notes that the leading countries in GNP production are the largest energy consumers in the world. The authors consider the issues of distribution of production and consumption of energy resources across the world, changes in the relationship between the leaders in primary energy production and energy consumption. Electricity consumption and production by regions of the world are considered, and the share of global energy intensity of energy by fuel type is determined. In addition, the article analyzes the world consumption of natural gas and coal, as well as its extraction. Changes in world demand for petroleum products and their consumption are considered.
Limiting state of plate with hole
Authors: Kazarinov Yu I
Published: November 2020

The problem of determining the limit state of a plate with hole is considered. Solutions of two other problems are proposed to solve this problem, namely, determination of stress intensity factor in elements of structure with cracks and calculation of stress-strain state of a plate of finite width with hole. The first objective is based on the fracture mechanics positions for the crack plate using the software complex KOMPAS-3D (3D design system). And the second objective is based on the theoretical method of elasticity theory, applied to a plate of finite width with hole. Obtained results of both objectives were compared with known solutions.
Application of PCIU for protection of emergency pipelines against corrosion
Authors: Saveleva N N , Salyakhova A R , Koretskiy K E , Koretskiy P E
Published: November 2020

The field pipelines at the Samotlor field are the main means of oil and gas transportation. Corrosion causes premature wear of pipes and piping equipment and can cause breakdowns. To prevent emergencies, it is necessary to carry out repair and technical work timely, using chemical dosing units. To protect the field pipelines at the Samotlor field, stationary reagent dosing units are used. All of them are installed at well pads, closer to automated group metering units. They have a number of significant disadvantages: difficulty in installing; difficulty of the repair work; impossibility to remotely control the process of pumping a chemical reagent in real time; long idle time; outdated security system. A modern solution to the listed above problems for the oil and gas industry is the use of portable chemical injection units (PCIU). A PCIU is a state-of-the-art trailer-based system, and it can also be installed permanently on a well pad. The advantage of this installation is its high mobility, ease of installing, minimal installation and maintenance costs, the ability to automate.
Improvement of pin flexible coupling construction
Authors: Saveleva N N , Savelev Y V
Published: November 2020

The purpose of the study is to increase the service life of coupling joints of centrifugal pumping units by designing a modernized coupling joint. During the operation of centrifugal units, there is a problem associated with a short service life of the couplings due to the imbalance of the half couplings, improper balancing of the rotor, etc. The authors conducted an objective and comprehensive analysis of the flexible coupling operation. Based on the results of the study of the existing construction, the coupling joint was modernized using the example of the pin flexible coupling for a centrifugal pump 200D90. The flexible coupling construction, which has no analogues in Russia, has been created. Due to the proposed upgraded construction, the coupling provides increased service life and more reliable operability in service.
Methods for illegal tapping detection using non-destructive testing tools
Authors: Salyakhova A R , Koretskiy K E , Koretskiy P E
Published: November 2020

The article discusses the statistics of accidents occurred as a result of illegal tapping or sabotage at the sections of the main oil pipeline. The authors analyzed existing methods for determining illegal tapping, revealed the need to develop such an advanced method for detecting tapping, which would combine several predominantly promising properties for the oil and gas industry. One of the main conditions for the development prospects is the environmental and economic feasibility of the development introduction. Significant advantages of the impulse reflectometry method are established, which consists in oil pipeline sounding, presented in the form of a two-wire electric line and detecting the wave resistance deviation at heterogeneous sections of oil pipeline. Various defects can present such deviations in comparison with the already existing control methods, which mainly depend on human factor during patrolling along the main oil pipelines.
Results of the experimental study of the fatigue characteristics of the repaired welded joint of the marine stationary oil and gas producing platform
Authors: Teodoriu C , Starokon I V , Guseynov Ch S
Published: November 2020

Offshore stationary platforms are actively exploited in the world. The lifespan of some of these platforms exceeds 20 years. Such a significant period of operation leads to the fact that the platforms are exposed to various loads for a long time, causing alternating stresses and, as a result, fatigue damage, including fatigue cracks in welded joints and the base metal of the platform. When fatigue cracks are identified, defect joints are repaired commonly using welding techniques. However, the duration of the subsequent operation of such repaired welded joints is not currently known. The authors conducted an extensive experimental study to understand the life span of welding repair technologies. This approach was for the first time used to repair the welded joint of a platform located in the White Tiger. White Tiger is the Vietnamese offshore oil field, located 200 km east of Ho Chi Minh City on the shelf of the South China Sea. The result of this study was the fatigue diagram and its equation, which were first obtained by the authors.
Experience in using the Russian LWD complex for well drilling
Authors: Davydov A Y , Yakhina I A
Published: November 2020

The experience of using the LWD production complex of Research and Production Company VNIIGIS-ZTK LLC, which allows you to track the lithology and thickness of the layers in the direction of drilling, to predict the point of entry into the reservoir, to conduct the well on the most productive part of the reservoir, is considered.
Intensification of the gas inflow when bringing wells into production
Authors: Dubinskiy G S , Andreev V E , Kuleshova L S , Mukhametshin V V
Published: November 2020

In wells brought into production, the bottomhole formation zone is contaminated. Contamination must be eliminated by acid treatment. The degree of contamination depends on reservoir characteristics and technological parameters of the primary and secondary opening. The intervals of formation permeability were identified; additional measures aimed at cleaning the reservoir from contamination and restoring well productivity should be implemented. Multi-solution acid treatment of the bottomhole formation zone improves productive characteristics of wells with deteriorated properties of the bottomhole reservoir.
Wave thermal flooding when designing high-viscosity oil reservoirs
Authors: Dubinskiy G S , Andreev V E , Mukhametshin V V , Kuleshova L S , Mingulov I Sh
Published: November 2020

The article describes an environmentally friendly and energy-saving method for increasing the volume of oil recovery - thermal flooding of a high-viscosity oil reservoir integrated with wave actions in injection wells. Heating of a remote formation zone to the effective temperature and wave impacts improve the conditions for effective oil displacement. The integrated use of associated gas and waste water from the oil treatment plant increases the energy efficiency and improves the environmental friendliness of small high-viscosity oil fields. For geological and physical conditions of high-viscosity oil deposits, it is recommended to employ the method of wave thermal flooding.
Stress corrosion cracking in pipelines
Authors: Gumerov A K , Khasanova A R
Published: November 2020

Stress corrosion is viewed as cracking of a pipe metal in cathodic protection regions of gas transmission pipelines, which are simultaneously affected by various unrelated, at first glance, factors. Stress corrosion is otherwise referred to as stress corrosion cracking or SCC. Stress corrosion cracking of pipelines is the main cause of emergencies in gas transmission pipelines. Currently, this type of corrosion is widespread and very dangerous. The reliability and safety of modern pipelines is of great national importance. Despite being significant, multiple efforts to address this problem have not yet identified the causes and algorithms for handling stress corrosion.
Set of measures to prevent liner sticking during directional drilling
Authors: Guseynova E L , Guseynov E M
Published: November 2020

The study considers the sticking problems of drilling. The study presents the classification and gives a general characteristic of liners. It is shown that the largest number of troubles occurs due to differential sticking. Differential sticking and methods of its elimination are considered in detail. The set of measures to prevent sticking, including the use of the Rhino XC Tool borehole expander, filters with plugs, dry lubrication, eccentric shoe, is developed and proposed.
Non-conventional methods for oil production in the conditions of the Abdrakhmanovskaya site of the Romashkino oil field
Authors: Gutorov A Yu
Published: November 2020

The paper analyzes the existing non-conventional methods for oil production in the conditions of the Abdrakhmanovskaya site of the Romashkino oil field. It describes the methods for well stimulation by swabbing in tubing strings (TS) and production casing (PC). A number of non-conventional production methods are compared to identify the most innovative. Some technical approaches are outlined once used in specific conditions to effectively deploy the operating well stock. The prospects for their use are evaluated.
Development of microcalcite-based drilling fluid
Authors: Ismakov R A , Dikhtyar T D , Yangirov F N
Published: November 2020

One of the most common hindrances to encounter during the construction of oil and gas wells is lost returns. The methods to select prevention and control measures are based on quantitative criteria that reflect the hydrodynamic capacity and geological structure of the strata. One of the ways to prevent this hindrance during the construction of oil and gas wells is pore-plugging – a sophisticated physicomechanical process to reduce the permeability of a reservoir formation, which takes place over time due to mud filtrates, dispersed particles or specially introduced fillers (plugging additives). For this reason, it seems relevant to use domestic microcalcite, as a component of drilling fluids, from the Minyar field. The paper aims to assess the effect of various microcalcite concentrations on the properties of drilling fluids and to assess as to whether this type of material is effective enough for pore-plugging under the specified drilling conditions.