bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of Viscosity Enhanced CO2 Nanofluid Alternating Gas in Light Oil Reservoirs
Authors: Gallo G. , Erdmann E. 
Published: May 2017

Abstract
Thickened CO2 nanofluids are a mean to improve volumetric sweep efficiency and gas production in CO2 EOR projects in contrast CO2 flooding. Alternating injection of plain CO2 with thickened CO2 nanofluid is proposed as an economical alternative using the findings of CO2 viscosity enhancement through nanoparticles in current studies. This was achieved by using CMG GEM simulator and contrasting findings with other WAG and CO2 flooding simulations. The simulation was done on a light oil (40 °API) from a Neuquén Basin reservoir. A sensitivity analysis was done to contrast different type of injection schemes.
As CO2 nanofluids can be tailor made in order to adjust their viscosity (and other properties like asphaltene deposition control) diverse results were observed. Nanofluids improve the volumetric sweet efficiency, and even low viscosity increment increase the overall gas utilization and conformance compared to CO2 flooding. Since there is no face change, the use of CO2 based nanofluids can be a mean to control CO2 EOR projects avoiding injectivity loss problems. It was observed that injection of mere nanofluid (without alternating CO2) is not technically nor economically convenient as it decreases production rates and has an overall lower economic performance than both WAG and CO2 flooding. Nevertheless, alternating nanofluid with plain CO2 enables higher sweep efficiency while lowering the operational costs due to lower volumes of nanofluid utilized. Adding nanofluid to a WAG scheme also shows improvements in EOR performance.
Evolution and Evaluation of SRV in Shale Gas Reservoirs: An Application in the Horn River Shale of Canada
Authors: Urban E. , Yousefzadeh A. , Virues C. J. , Aguilera R. 
Published: May 2017

Abstract
A hybrid hydraulic fracture (HHF) model composed of (1) complex discrete fracture networks (DFN) and (2) planar fractures is proposed for modeling the stimulated reservoir volume (SRV). Modeling the SRV is complex and requires a synergetic approach between geophysics, petrophysics, and reservoir engineering. The objective of this paper is to characterize and evaluate the SRV considering the initial hydraulic fracturing efficiency, fracture network complexity, mechanics, and microseismicity distribution along 145 stimulated stages in a multilateral horizontal well on the Muskwa, Otter Park and Evie Formations in the Horn River Shale in Canada.
Hydraulic fracturing jobs in shale reservoirs are designed with a view to achieve economic production by exploiting fracture network complexity. The task involves significant challenges in modeling and forecasting, which complicates the examination of operations to enhance their performance, including refracturing or infill drilling.
In this study, an HHF is run in a numerical simulation model to evaluate the SRV performance in planar and complex fracture networks using microseismicity data collected during 75 stages of hydraulic fracturing in the Horn River shale. Post-fracturing production is appraised with Rate Transient Analysis (RTA) for determining effective permeability under flowing conditions, compare to the numerical simulation and the hydraulic fracturing design.
Fracturing stages with larger fracture patch sizes, associated with the microseismic events in a fixed stress drop, correspond to higher stimulated areas, fracture conductivity, and gas production. Several microseismic events are observed in the heel of the laterals that are aligned to the far field NE stresses, indicated a loss of efficiency along the wellbore lateral during hydraulic fracturing. The hydraulic propagation modeling revealed increment of the leak-off coefficient, related to the natural fractures and communication with other stages. The production performance is evaluated in the numerical model, to measure interference between stages.
The SRV, modeled with HHF networks, is able to match the post-fracturing production history. Fracture mechanics is important in order to understand the flowing performance of the reservoir.
The inclusion of propagating models and RTA allowed to characterize possible fracture geometries in the reservoir and to observe limitations inherent to large dispersion and uncertainty of the microseismicity cloud. Also, to observe areas where the stimulation may have propped natural fractures totally or partially, which will benefit the production of gas.
This study presents a better understanding and characterization of the SRV in shale gas reservoirs, especially in those cases where microseismicity dispersion is problematic and where the SRV is not easily delimited.
A Comprehensive Workflow for Near Real Time Waterflood Management and Production Optimization Using Reduced-Physics and Data-Driven Technologies
Authors: Maqui A. F. , Zhai X. , Suarez Negreira A. , Matringe S. F. , Lozada M. A. 
Published: May 2017

Abstract
Optimizing waterfloods in large fields with complex geology can be an extremely difficult engineering problem. Simulations become overwhelming and tremendously time consuming, while basic classical engineering will not capture enough physics to assess well by well decisions. In this paper we present a novel data-driven, reduced-physics workflow to manage and optimize an exceptionally complex reservoir in Latin America.
The first stage of the workflow involves collecting and validating the field data, including rock and fluid properties, production, injection and pressure data as well as well information, such as trajectories and historical perforations. The reservoir behavior is then modeled following an approach similar to the one by Thiele and Batycky (2006) in the context of streamline simulation. The model represents the reservoir as a network of inter-well connections described by their strength and efficiency. The strength of connection is determined through the solution of a numerical tracer test rather than through streamline-based method like in Thiele and Batycky (2006), which generalizes the method to unstructured or locally refined grids as well as dual permeability systems and allows the method to account for compressibility effects. An empirical fractional flow model is then used to calculate the connection efficiencies. Once the model is complete and calibrated, a cutting-edge optimization algorithm is used to optimize the production-injection strategy based on this network of subsurface connections. Recommendations for adjustments in the production-injection strategies are proposed and model uncertainties are computed through a novel algorithm to compute the associated risks.
The proposed methodology was successfully applied to a giant Latin American waterflooded reservoir with over 800 wells and nearly a hundred years of history. The approach identified an optimized strategy that could deliver a 5% increase in oil production with a 10% reduction in water production. The methodology proposed is fast enough to build and match a new model in a few days; and updating an existing model takes less than an hour as new data comes available.
The proposed method was designed to avoid expensive numerical simulation and to simplify the history-matching process. It can therefore be used daily to help engineers optimize the production-injection strategy of reservoirs. Furthermore, the model can be used for robust short-term forecasting as well as relatively elaborate production mapping.
Wave intensity analysis and its application to the coronary circulation
Authors: Broyd C J , Davies J E , Escaned J E , Hughes A , Parker K 
Published: May 2017

Wave intensity analysis (WIA) is a technique developed from the field of gas dynamics that is now being applied to assess cardiovascular physiology. It allows quantification of the forces acting to alter flow and pressure within a fluid system, and as such it is highly insightful in ascribing cause to dynamic blood pressure or velocity changes.When co-incident waves arrive at the same spatial location they exert either counteracting or summative effects on flow and pressure. WIA however allows waves of different origins to be measured uninfluenced by other simultaneously arriving waves. It therefore has found particular applicability within the coronary circulation where both proximal (aortic) and distal (myocardial) ends of the coronary artery can markedly influence blood flow. Using these concepts, a repeating pattern of 6 waves has been consistently identified within the coronary arteries, 3 originating proximally and 3 distally. Each has been associated with a particular part of the cardiac cycle. The most clinically relevant wave to date is the backward decompression wave, which causes the marked increase in coronary flow velocity observed at the start of the diastole. It has been proposed that this wave is generated by the elastic re-expansion of the intra-myocardial blood vessels that are compressed during systolic contraction. Particularly by quantifying this wave, WIA has been used to provide mechanistic and prognostic insight into a number of conditions including aortic stenosis, left ventricular hypertrophy, coronary artery disease and heart failure. It has proven itself to be highly sensitive and as such a number of novel research directions are encouraged where further insights would be beneficial.
Mechanistic targets for the ablation of atrial fibrillation
Authors: Zaman Junaid AB , Baykaner Tina , Schricker Amir A , Krummen David E , Narayan Sanjiv M 
Published: May 2017

The mechanisms responsible for sustaining atrial fibrillation are a key debate in cardiovascular pathophysiology, and directly influence the approach to therapy including ablation. Clinical and basic studies have split AF mechanisms into two basic camps: ‘spatially distributed disorganization’ and ‘localized sources’. Recent data suggest that these mechanisms can also be separated by the method for mapping – with nearly all traditional electrogram analyses showing spatially distributed disorganization and nearly all optical mapping studies showing localized sources We will review this dichotomy in light of these recently identified differences in mapping, and in the context of recent clinical studies in which localized ablation has been shown to impact AF, also lending support to the localized source hypothesis. We will conclude with other concepts on mechanism-based ablation and areas of ongoing research that must be addressed to continue improving our knowledge and treatment of AF.
Dynamic modelling and control for fully-steerable large reflector antenna considering rigid-flexible coupling
Authors: Li Sulan , Bao Hong , Wang Congsi 
Published: May 2017

As the size of reflector antenna increases, the influence of flexible deformation to the system dynamics is much more significant. The coupling between the flexible deformation and the rigid displacement needs to be considered. However, the traditional dynamic modelling and control method for large reflector antenna ignores this coupling. To overcome this problem, this paper proposes a dynamic method based on Lagrange Principle, and the corresponding control strategy is discussed. Finally, we take a 110 m diameter fully-steerable antenna as an example to carry out this method. All the results show that the method is stable and with high precision. It will also lay a solid foundation for the high-precision pointing of large reflector antenna.
Feature extraction and fault diagnosis of wind power generator vibration signals based on empirical wavelet transform
Authors: Chen Xuejun , Yang Yongming , Yang Ning 
Published: May 2017

Given the nonlinear and nonstationary characteristics of wind power generator vibration signals, the empirical wavelet transform (EWT)-based method is proposed to analyze the vibration signal characteristics and to diagnose faults. The adaptive Fourier spectrum segmentation of EWT is analyzed, and an appropriate wavelet filter is constructed to extract different AM-FM mode functions. The Hilbert transform is conducted, and the signal modal component energy is normalized to obtain vibration feature quantities. A probabilistic neural network (PNN) is used to perform the classification and diagnosis of wind power generator vibration faults. The experiments are constructed based on simulation signals and vibration signals before the proposed method and Hilbert-Huang transform (HHT) are used to perform mode decomposition and to analyze the time-frequency energy spectrum. The experimental results showed that the obtained resolution modes by EWT are within the corresponding time domain signal characteristics. The number of mode decomposition layers is less than that of empirical mode decomposition. No characteristics of false modal are observed. The time-frequency energy spectrum diagram can better reflect the characteristics of original vibration signal than the spectrum based on HHT. The PNN-based vibration fault judgment can achieve an accuracy rate of 90 % with limited training samples.
Research on the ultrasonic testing of defect for LY12 aluminum alloy based on transmission wave in lamb wave
Authors: Chen Xinya , Chen Zhen 
Published: May 2017

Aimed at the problem that the ultrasonic testing is applied in defect of LY12 aluminum alloy by using liquid or semi-solid coupling agent, transfer matrix method and gas-solid boundary conditions of ultrasonic wave propagation is used for establishing mathematic model in LY12 aluminum alloy, and this model is solved to obtain the propagation characteristic curve. When cut-off frequency is less than 2 MHz·mm, it has only S0 modal. The simulation result provides proper parameters for ultrasonic testing, in which the incidence angle is 30° and the center frequency is 1 MHz. The different circuit defect for LY12 aluminum alloy is made and detected, and time domain waveform is obtained. The experimental results show that the diameter of the defects has a little influence on the amplitude of the direct wave, defect wave amplitude decreases gradually with the increase of the defect diameter.
Real-time stall detection of centrifugal fan based on the analysis of symmetrized dot pattern and wavelet packet transform
Authors: Xu X. G. , Liu H. X. , Wang S. L. , Fan Z. Y. , Yang L. J. , Liu S. T. 
Published: May 2017

This paper presents a novel stall detection method based on symmetrized dot pattern (SDP) analysis, which detects the starting point of rotating stall timely and accurately during operations of centrifugal fans. To demonstrate the proposed method, experiments were first performed on a G4-73 No. 8D centrifugal fan to measure the aerodynamic pressure signals of the air flow inside the fan during the gradual development of rotating stall. Then, the SDP technique was used to analyze the pressure signals and extract the time-domain characteristics of the pressure signal during the gradual development of rotation stall. Finally, a comprehensive autocorrelation coefficient was defined and employed as the index for real-time stall detection. In addition, to verify the accuracy of detection results, the tested signals were also analyzed off-line by wavelet transform to detect the actual starting point of rotating stall. The comparison results show that the stall detection method based on the symmetrized dot pattern (SDP) analysis can accurately detect the starting point of rotating stall in centrifugal fans within a short period of 0.05 s.
Numerical study on parameter impact on fundamental frequencies and dynamic characteristics of pre-stressed concrete beams
Authors: Cui Kai , Zhao Ting-ting , Gou Hong-ye 
Published: May 2017

This paper established 6 kinds of different concrete beams, and 5 kinds of models were applied horizontal pre-stress. Their fundamental frequencies and deflections were numerically computed, and the correctness of numerically computational model was experimentally verified. Fundamental frequencies of 6 kinds of models were 46.23 Hz, 68.45 Hz, 69.36 Hz, 70.46 Hz, 72.11 Hz and 157.73 Hz respectively. Concrete beams without being applied pre-stress had a low fundamental frequency. The fundamental frequency of concrete beams could be obviously improved through internally applying pre-stressed tendons to concrete beams. In addition, the improvement effect of Model 5 was more obvious. When pre-stressed tendons were externally applied to the concrete beam, the fundamental frequency was greatly improved. However, externally pre-stressed tendons would limit the use of concrete beams and increase the cost. When other parameters remained unchanged, the fundamental frequency of pre-stressed concrete beams would gradually increase with the increase of pre-stress. When the pre-stress was the same, fundamental frequencies gradually increased with the increase of eccentricity, the number of circular tendons in composite tendons and concrete strength, and gradually decreased with the increase of counterweight. When the applied load was the same, Model 1 was not strengthened and its deflection was the largest. On the contrary, the model which was applied external pre-stress and its deflection was the smallest, but its use was limited and cost was high. In the strengthening proposals of internal pre-stress, composite tendons were applied to Model 5, and it presented a small deflection. When other parameters remained unchanged and the applied load was lower than a value, the deflection of concrete teams gradually increased with the increase of applied load. On the contrary, the deflection of concrete beam tended to be stable with the increase of applied load. When the applied load was the same, the deflection of concrete beams gradually decreased with the increase of eccentricity, the number of circular tendons in composite tendons and concrete strength, and gradually increased with the increase of counterweight.
Pengaruh Jigsaw Dan Motivasi Belajar Pada Mapel Bahasa Inggris “Reported Speech” Terhadap Hasil Belajar Siswa Kelas X SMA Taman Madya Kota Probolinggo
Authors: Indrianie Niken Shali 
Published: May 2017

AbstractThis research is aimed to know the result of the study of the students on the English subject “Reported Speech” by using cooperative learning strategies model jigsaw in relation to the students’ motivation. This research is conducted on SMA Taman Madya, Probolinggo city by using quantitative approach. The data of the research is collected from the observation to the teacher, students’ activity, and the ability on English test “Reported Speech”. The source of the data are the students of tenth grade and observation on the school’s activity. The result of this study shows that the cooperative learning model jigsaw is well-applied in parallel to the lesson plan. The students’ activity in a group is well-conducted ad able to follow its function. The skill of the students in the learning and teaching of material and topics to the group is well-conducted and resulted in clear understanding and ability to solve the problem of English “Reported Speech” by the other students, as well as a well-conducted finishing steps and a well-established steps on doing the evaluation to show an enhanced result of study. Keywords: cooperative learning, jigsaw, learning motivation, result of study AbstrakPenelitian ini bertujuan untuk mengetahui hasil belajar siswa pada mata pelajaran bahasa Inggris “Reported Speech” dengan menggunakan pembelajaran cooperative learning model Jigsaw yang dikaitkan dengan motivasi belajar siswa . Penelitian ini dilaksanakan di SMA Taman Madya Kota Probolinggo dengan menggunakan pendekatan kuantitatif. Data penelitian berupa observasi aktivitas guru, aktivitas siswa dan kemampuan mengerjakan soal dalam bahasa Inggris “Reported Speech”. Data Penelitian bersumber pada peserta didik kelas X dan observer yang melaksanakan penelitian di sekolah tersebut. Hasil penelitian menunjukkan bahwa pembelajaran cooperative learning model Jigsaw terlaksana dengan baik sesuai dengan sintak pembelajaran yang direncanakan. Aktivitas setiap siswa yang belajar secara berkelompok dapat berperan dan dapat melaksanakan fungsinya dengan baik. Kemampuan setiap siswa dalam belajar dan mengajarkan materi/pokok bahasan kepada temannya yang lain dalam kelompok dapat berlangsung dengan baik sehingga temannya mampu untuk memahami dan memecahkan masalah bahasa Inggris “Reported Speech” dengan baik, dan pada langkah penyelesaian serta langkah mengerjakan soal evaluasi (tes) dapat terlaksana dengan baik serta menunjukkan hasil belajar yang cukup meningkat . Kata kunci: cooperative learning, jigsaw, motivasi belajar, hasil belajar
Writing Factual Report: A Potential Way To Enhance Student’s Critical Thinking Ability
Authors: Anwar Khoirul , Iramawaty Lathifah 
Published: May 2017

ABSTRAKTerdapat banyak perubahan yang terlihat jelas diantara penggunaan KTSP dan kurikulum 2013 dimana kurikulum 2013 dirancang dengan lengkap untuk menghasilkan kompetensi siswa yang memiliki kemampuan berpikir kritis. Karena hal ini adalah tantangan bagi para guru, artikel ini bermaksud untuk mendiskusikan dan menganalisis bagaimana menulis laporan faktual dapat meningkatkan kemampuan berpikir kritis para siswa. Pentingnya kemampuan berpikir kritis dan strategi yang digunakan untuk meningkatka kemampuan berpikir kritis siswa juga manjadi salah satu bahasan artikel ini. Tujuan penulisan artikel ini lebih lanjut untuk memberikan deskripsi jelas terhadap kemampuan berpikir kritis dan prosedur yang disarankan untuk menggunakan metode menuliskan laporan faktual pada pengajaran Bahasa Inggris sebagai bahasa asing. Lebih lanjut, menggunakan metode menuliskan laporan faktual secara jelas dapat menmbantu meningkatkan kemampuan berpikir kritis siswa yang merupakan tujuan paling utama dalam pengajaran Bahasa Inggris sebagai bahasa asing pada masa ini. Kata kunci: Laporan Faktual, Berpikir Kritis Kemampuan. ABSTRACTThere are a lot of changes which are quite prominent between KTSP and 2013 curriculum in which the latest one was highlydesigned for producing students’ competencies to have critical thinking ability. Since this is challenging for teachers, this article is to discuss and analyze about how writing factual report enhances students’ critical thinking. The importance of critical thinking and strategies used to increase students' ability to think critically is also discussed. The aim of this article is further to give aclear description of critical thinking and the suggested procedures of using writing factual report in EFL teaching. Furthermore, using writing factual report can definitely help enhance students’ critical thinking which is extremely as the most important goal in EFL teaching nowadays. Keywords: Factual Report, Critical Thinking Ability