bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of Additional Mass Effect on Dynamic Wing Model Stability in Airflow
Authors: Naumov A. M. 
Published: January 2020

The paper investigates a dynamic stability of the wing model in the flow of incoming air. As is known, at a certain flow rate, called critical, there occurs a phenomenon of self-excited non-damping flexural-and-torsional self-vibrations, called flutters. The paper considers an anti-flutter approach that is the placement of additional weight on the elastic elements (springs) in the wing model. Thus, a three-stage wing model is under consideration while the publications concerning this problem more often describe a two-stage wing model. The paper is a natural sequel to the authors’ first paper [9] where a two-stage wing model was considered in detail. It continues and develops research in this area, conducted by many famous scientists, such as V.L. Biderman, S.P. Strelkov, Ya.G. Panovko, I.I. Gubanova, E.P. Grossman, J.C. Fyn and many others who have investigated this phenomenon. It is also necessary to mention the scientists, namely Keldysh M.V., Reese P.M., Parkhomovsky Y. M., etc. who not only studied this phenomenon, but developed anti-flutter methods for it.It should be noted that not only scientists-theoreticians, but also test pilots, in particular M.L. Gallay [8], contributed to the solution of the flutter problem. The paper describes in detail a derivation of the linear differential equations of small vibrations of a wing model with additional weight in the flow, determines the eigenfrequencies and forms of flexural-and-torsional vibrations, checks their orthogonality, explores the forced vibrations under aerodynamic force and moment, and estimates a critical flow rate for a number of system parameters, namely a mass of the additional weight and the rigidity of its suspension. The conclusion is drawn that these parameters effect on the critical rate. Based on the calculation results, one can come to the conclusion on the additional weight effect on the critical flutter speed and on how relevant the anti-flutter method is. The given paper may be of interest both for students of technical specialties who learn the theory of mechanical vibrations, and for engineers majoring in aero-elasticity and dynamic stability of the elements of mechanical systems.
The role of financial literacy in retirement investment choice
Authors: Nguyen Thi Anh Nhu , Polách Jiří , Vozňáková Iveta 
Published: January 2020

Research background: Preparation for retirement is a major concern for the people in the workforce as they have to encounter considerable difficulties in making the right investment decisions for their retirement.
Purpose of the article: This research extends the literature on personal finance by investigating the impact of both financial literacy levels and pension knowledge on employees? investment choice decision for their retirement, while in previous literature the role of these factors has mainly been explored separately.
Methods: To conduct the research, a survey questionnaire was applied to collect data in three main regions of Vietnam comprising Northern, Central and Southern Vietnam. Data collection was made in 2018, in which 427 valid questionnaires were used for data analysis from 700 questionnaires. Two estimation methods are employed for analysis in this study, including a linear probability model (LPM) and two-stage least squares (2SLS) model. The findings of this research remain significant after the Two-Stage Least Squares (2SLS) regression model is used as an estimation technique to eliminate potential bias caused by endogenous problems.
Finding & Value added: The results show that basic financial literacy level and pension knowledge are principal factors which significantly increase the probability of exercising retirement investment choice of employees, while advanced financial literacy level factor has a significant effect on choosing growth investing options for their retirement. Further, this research finds that there is no correlation between employees? financial risk tolerance and their retirement investment choice. Furthermore, the study proposes and offers new evidence that pension knowledge is a decisive factor providing employees with encouragement to exercise retirement investment choice and those who consult with financial advisors tend to take part in growth investing option.
Controlling as a tool for SME management with an emphasis on innovations in the context of Industry 4.0
Authors: Pisar Premysl , Bilkova Diana 
Published: January 2020

Research background: Small and medium-sized businesses are significant economic power and employer in the European Union. The modern globalized world, new technologies, and advanced connectivity bring SMEs a wide range of opportunities, but also threats. Increasing the stability and competitiveness of SMEs is one of the main goals of national governments and the EU. The research is based on personal research in SMEs, its experiences and backward testing of reached results.
Purpose of the article: The aim of the paper is to analyze the possibilities the potential of using controlling as a managing tool of SMEs for increased competitiveness in the context of Industry 4.0 with an emphasis on innovations.
Methods: The study is based on a detailed analysis of 341 SMEs from the Czech Republic obtained in the years 2017?2019. The data were analyzed using statistical methods such Pearson correlation, stepwise regression for the purpose of determining the relationship between the controlling management system of a company, its innovation potential, level of process maturity, number of employees, internal audit, financial stability and strategic plan. Statistical analysis confirmed the close relationship of the analyzed variables and backwards experimental testing of the statistical analysis conclusions defined critical factors in the area of people in an organization, usage of advanced information systems and Industry 4.0 technologies implementation.
Findings & Value added: Those important areas were determined as essential for the successful development of SMEs, as well as the most significant threats in the Industry 4.0 environment. The information obtained is useful in practice and can be applied to a more in-depth analysis of the issues. The research findings are showing possible opportunities and treads for SMEs long term stability and development as well as ways to increase enterprise performance based on controlling management system.
European union emissions trading system with regard to climate change mitigation in Latvia
Authors: Pruse Ilze 
Published: January 2020

Abstract
The goal of this paper is to analyse the volumes of greenhouse gas (GHG) emissions from the European Union Emissions Trading System’s (EU ETS) participants in Latvia in relation to their participation therein. After describing and discussing the EU ETS mechanism and its operation in Latvia in the period 2005-2010, the interconnectedness between the GHG emissions and the EU ETS participants’ operation is analysed. The analysis concludes that, although the EU ETS has contributed towards GHG emission reduction, due to the growth of the economy, overall GHG emissions from the EU ETS participants in Latvia are increasing.
Optimizing Completion and Re-Fracturing Opportunities via Diversion
Authors: Omer Mohammed , Perez Oswaldo , Fragachan Fragachan E. 
Published: January 2020

The main objective of diversion is to enhance contact of the stimulation fluid with the reservoir. If the diversion is designed by trial and error, without proper understanding of physics behind particle size distribution, and pumped downhole the uncertainty will be high and it will reduce the effectiveness of stimulating job.
Stimulating fluids pumped into a reservoir takes the least resistance path and goes into areas where often the stimulation is not required to increase production. The success of a hydraulic fracturing or acidizing treatment depends on maximizing the contact and distribution between the stimulation treatment and the reservoir. To achieve this goal, existing fluid paths must be efficiently temporarily blocked and divert the treatment fluid towards under-stimulated areas, which should maximize production.
The diversion is being widely used but it is not being focused on optimizing completion via an engineering approach. This paper will present a comprehensive discussion around missing factors associated with jamming and plugging efficiency, particle size, particle shape, frictional parameters, particle concentration, opening geometry, rate during placement, and particles size distribution and ratio. It will clearly highlight the importance of optimizing completion and re-fracturing opportunities via diversion.
Multiple experiments were conducted to quantify the effect of the different factors that dictate the overall goal of a successful diversion treatment. An analytical model based on computational fluid dynamics and discrete element modelling was developed, and calibrated with experimental results to optimize the different parameters that affect an optimum diversion. One of these key paramenters is the displacement rate during diverter injection, including determining the required spacers to minimize particle dispersion, ensuring the diverter pill arrives on formation intact and as designed to effectively create the temporary resistance required to effectively divert to under-stimulated areas.
Determining the Magnitude of Interference Among Adjacent Wells in a Saudi Arabian Unconventoinal Formation
Authors: Abaza Bayan , Baki Sohrat , Sadykov Almaz , Mechkak Karim , Rueda Jose 
Published: January 2020

Gaining an understanding of the well to well interference during hydraulic fracturing and subsequently production interference is paramount in optimizing the costs associated with field development. Much work has been done in the industry to better understand the interference during hydraulic fracturing and production among adjacent wells. This paper presents an analysis that employed both a pressure interference analysis and chemical tracer analysis to gain a better understanding of the fracture interference in a well pad in the Jafurah field. The subject pad consists of 4 wells. Two of which run parallel in a north direction and the other two run parallel in the southern direction. All four wells were hydraulically fractured with slickwater design. Adjacent to the subject pad is another pad that had been previously stimulated with crosslink design and was used for pressure monitoring. The distance between the laterals was relatively similar (X ft) with one exception (2 × ft).Initially, one well from both directions was stimulated with 33 stages each of slickwater design and the plugs were subsequently milled out. Afterwards, the other two wells were stimulated with 33 stages of slickwater each. In 7 of the 33 stages of the later wells, 20 oil and 20 water tracers were injected in sequence in an attempt to study the physical extent of the fractures generated. While the latter two wells were being stimulated, the wellhead pressure on the parallel wells was being monitored and recorded along with the wellhead pressures on the adjacent pad.During flowback, the southern wells were flowed back simultaneously and flowback samples were collected to be analyzed for tracers. Subsequently, the northern wells were opened up to flowback in the same manner and flowback samples were also collected for tracer analysis. Wellhead pressure was monitored on the adjacent pad during flowback of all the wells.The pressure data during the fracturing operation indicated for distance × ft and the size of stimulation stages pumped, a level of communication which was further verified by the production interference analysis as well as the tracer data.
Down Hole Barrier Valve Technology - Reducing Formation Damage and Improving Recovery
Authors: Wickramasinghe Tharinda 
Published: January 2020

This paper describes the challenges faced when completing wells in the Mishrif formation of Southern Iraq, where well control concerns increase post acid stimulation of the reservoir due to the unpredictability of the formation's behavior.
One of the biggest challenges faced when drilling and completing in this formation is to manage a natural hydraulic balance of the reservoir to avoid the well switching from losses to kicks without warning. While this challenge is being addressed by carefully selecting drilling and completion fluids of specific densities, it has not been fully mitigated as wells have shown signs of switching state arbitrarily specifically post acid stimulation operations. In light of this challenge a completion design was proposed that incorporated a downhole bi-directional barrier valve which would ensure that the well bore would be secure upon installation of the lower completion. It was envisaged that this technology would help overcome any dynamic changes of the reservoir that may lead either to fluid loss, risking damage to the reservoir or kicks risking a catastrophic blow out.
A typical production well architecture in the Mishrif formation of the West Qurna-2 field would consist of 9-5/8′ production casing to surface and an 8-1/2′ Open Hole section that would be completed with either 7′ slotted or perforated liner. Well trajectories could vary from vertical to a maximum deviation of 60 degrees in most cases. The proposed design was to complete a few of the early phase wells using 9-5/8" × 5-1/2" mechanical ball valves incorporated into the lower completion which would therefore serve as a bi - directional barrier once installed and shifted closed.
Modeling Liquid Holdup in Pseudo-Slugs
Authors: Fan Yilin , Al-Safran Eissa , Pereyra Eduardo , Sarica Cem 
Published: January 2020

Pseudo-slug flow is a sub-regime of intermittent flow that is characterized by short, undeveloped, frothy chaotic slugs, with translational velocity less than the mixture velocity of the fluids. Pseudo-slug flow does not comply with the basic characteristics of conventional unit-cell slug flow where liquid blocks the entire pipe cross-sectional area, and liquid is scooped at slug front, transferred to slug body, and shed back to liquid film. The liquid in pseudo-slug body is insufficient to reach the upper part of the pipe wall, resulting in only large wave with entrained gas bubbles at the bottom part of the pseudo slug body. Consequently, a significant reduction in the gas phase flowing area above the wave is formed, which increases the local gas velocity, entraining large volume of liquid droplets in the upper part of the slug body. Therefore, the pseudo-slug body can be divided into two regions, liquid film (wave) with entrained gas bubbles at the bottom, and gas core with entrained liquid droplets. The objective of this study is to develop a plausible physical model of the experimentally observed pseudo-slug liquid holdup phenomenon and model the physical and hydrodynamic behavior using a dimensional regression modeling approach.
This paper discusses liquid and gas entrainment mechanisms within pseudo-slug body based on experimental observation. Previous experimental results show that the proposed dimensionless groups; namely, Stokes, Slippage, and Poiseuille are strongly correlated to pseudo-slug body liquid holdup experimental data and are capable of describing the experimentally observed physical behavior. A linearized regression model is developed to combine the liquid holdup proportionally in both regions of the pseudo-slug body (mentioned above) and correlate them to the experimentally measured total pseudo-slug liquid holdup using wire mesh sensor. A validation study of the proposed model with Fan (2017) experimental data shows good agreement, outperforming all other existing slug liquid holdup correlations.
Advanced Integrated Subsurface 3D Reservoir Model for Multistage Full-Physics Hydraulic Fracturing Simulation
Authors: Izadi Ghazal , Guises Romain , Barton Colleen , Randazzo Santi , Mahrooqi Shabib , Shaibani Mahmood , Dobroskok Anastasia 
Published: January 2020

A fit-for-purpose integrated subsurface study was carried out in a tight gas field in Oman to evaluate the stimulation process in horizontal wells. The objective is to explore the role of vertically and laterally heterogeneous in situ stress for hydraulic fracture (HF) propagation, and to quantify its effect on hydraulic fracture stimulation efficiency using a 3D fully-coupled hydraulic fracturing simulator for complex geological conditions. The use of advanced simulation tools that realistically predict the evolution of stresses in 3D allows us to explore the parameter space required to optimally design stimulations for complex tight and unconventional field development [Izadi et al. 2017; Cruz et al. 2018; Izadi et al. 2018].
The goal of this study is to test scenarios that increase production through reservoir contact by use of various fracturing techniques that improve the Stimulated Rock Volume (SRV).
The modeling scenarios include an assessment of:
The impact of high vs. low in situ stress on pressure response, proppant placement and near wellbore conductivity
The impact of in situ stress magnitude in near wellbore conductivity
The impact of fluid properties and landing zone on proppant transport
The effect of laminations on proppant transport
The impact of HF/natural fracture interactions on SRV
This study illustrates that for complex reservoirs where spatial heterogeneities, preexisting natural fractures, or transitional stress states are present, advanced 3D modeling provides insight critical to optimize development strategy. Through parametric stimulation modeling design, mechanisms driving drilling, completion, stimulation and productions processes can be honed to optimize and better manage the primary risks to development in tight/unconventional reservoirs .
A Novel Method of Crude Oil Water-Cut Detection Based on Multi-Sensor Fusion
Authors: Ren Guishan , Ge Dangke , Sun Kai , Chen Xuemei , Mi Lifei , Yao Xizhi 
Published: January 2020

Water-cut detection of crude oil based on capacitive sensors and conductivity sensors are widely used in practice. However, the above two methods cannot achieve full-scale measurement of water-cut of crude oil. Besides, their measurement accuracy is sensitive to temperature, which greatly limits their application. A novel method of crude oil water-cut detection based on multi-sensor fusion is proposed in the paper.
The proposed method uses a capacitive sensor and a conductivity sensor to measure the crude oil separately, and uses a temperature sensor to compensate the measurement result at the same time. Finally, the proposed method introduces a neural network for data fusion to predict the water content. The experiment results show that the proposed multi-sensor fusion technique performs better than capacitance and conductivity technique. The accuracy of this method is higher than single capacitance or conductivity method. When the water content is lower than 3%, the prediction error is less than 0.1%. When the water content is in a range from 3% to 10%, the prediction error is less than 0.5%. When the water content is in a range from 10% to 100%, the prediction error is less than 1.5%.
Advances in LWD Sigma and a Novel Approach for Saturation Evaluation by Combining Resistivity and Capture Sigma for Low-Resistivity Pay Reservoirs
Authors: Majumdar Chandan , Adonis Ebozogo Mvou Hans 
Published: January 2020

Conventional resistivity-based water saturation estimates using Archie's equation depend on petrophysical parameters strongly related to reservoir rock texture, pore structure, wettability, and formation salinity. These parameters are often not readily available and can vary significantly within and across depositional sequences. At the same time, for high-angle wells, the different bed boundary effects mask the true formation resistivity only to add to the grim of saturation evaluation. This makes formation sigma particularly interesting because it offers saturation estimation independent of resistivity measurement and empirical Archie exponents. However, the method has not been extensively used as the unknown invasion effect in single-depth sigma measurement can lead to erroneous interpretation.
With the availability of multiple-depth-of-investigation (MDOI) formation sigma, the latest logging-while-drilling (LWD) service provided means to invert for undisturbed formation sigma (Mauborgne et al. 2013). An invasion-free sigma and the resistivity log can be used together to simultaneously solve for the Sw and formation water salinity with a reasonable knowledge of the porosity and Archie parameters (m and n). The method solves for a salinity value that is consistent with the Sw calculated from resistivity and from sigma.
This technique was used for the first time to evaluate Sw in the Gamba-sand and Dentale, a reservoir with very low resistivity. Following the success, the method was used in another field (Robin) to evaluate similar reservoirs. The technique provided accurate oil saturations in the oil leg and proved its applicability in these fields. This paper will illustrate the methodologies of deriving true formation sigma and the advanced steps for combining sigma and resistivity to derive a precise answer.
The availability of LWD sigma opened new frontiers of applications beyond the conventional baseline monitoring logs. The capability of deriving true formation sigma along with the novel technique of integrating two different measurements, sigma and resistivity, to derive one single answer was the key to the success.
Implementation of SAK EMKM in CV Adro Textile through an Action Research Approach as a Form Financial Management Accountability
Authors: Farhan Ali , Mulyono Resha Dwi A. P. 
Published: January 2020

Most of micro business industries have a problem on accountabilty and lack of information on financial and management knowledges. CV Adro Textile is one of the micro business which faced those problems. This research aims to introduce an accounting policy and standard into action research methodolgy for a micro business such as CV Adro Textile. CV Adro textile is a manufacturing company that engaged in the garment sector. During its business, CV Adro Textile faced some problems regarding to the financial information. CV Adro Textile cannot ensure the profit that been generated, the cash turnover, and the production cost as well as the financial information for the taxation need. Through the action research, this research tried to implement the EMKM financial accounting standard to fulfill CV Adro Textile’s needs to the accountable financial statements. Action research is a research procedure aims to implement a new policy based on needs and problems of the research object. The results of this research were an accounting recording system for CV Adro Textile based on SAK EMKM and an evaluation of the SAK EMKM application that apparently could not accommodate the whole recording needs and information of an industry. This paper contribute to the way of intorducing an accounting standart into a micro entity