bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic Particle Simulations of Plasma Charging at Lunar Craters Under Severe Conditions
Authors: Lund David , He Xiaoming , Han Daoru
Published: February 2023

This paper presents fully kinetic particle simulations of plasma charging at lunar craters with the presence of lunar lander modules using the recently developed Parallel Immersed-Finite-Element Particle-in-Cell (PIFE-PIC) code. The computation model explicitly includes the lunar regolith layer on top of the lunar bedrock, taking into account the regolith layer thickness and permittivity as well as the lunar lander module in the simulation domain, resolving a nontrivial surface terrain or lunar lander configuration. Simulations were carried out to study the lunar surface and lunar lander module charging near craters at the lunar terminator region under mean and severe plasma environments. The lunar module’s position is also investigated to see its effect on the plasma charging relative to the craters. Differential surface charging was clearly resolved by the simulations. For the charging of a lunar lander module made of conducting materials, the results show a near-uniform potential close to that of its surrounding environment and moderate levels of local electric fields. Additionally, the risks associated with charging and discharging increase significantly under a more severe plasma charging environment as shown in the severe plasma environment cases.
Dynamic Machine Learning Global Optimization Algorithm and Its Application to Aerodynamics
Authors: Zhang Zi-Qing , Li Pei-Jing , Li Qing-Kuo , Dong Xu , Lu Xin-Gen , Zhang Yan-Feng
Published: February 2023

A dynamic extreme gradient boosting (XGBoost) and MaxLIPO trust region parallel global optimization algorithm is proposed in this paper, and it is applied to the turbomachinery blade aerodynamic optimization coupled with an in-house graphics processing unit (GPU) heterogeneous accelerated compressible flow solver, AeroWhale. The algorithm combines an accurate machine learning regression model, an efficient nongradient optimization method with no hyperparameters, a dynamic update regression strategy, and double convergence criteria to achieve high optimization accuracy and efficiency. The optimization results on the test function indicate that the number of objective function calls is less than 2% of that required by a traditional genetic algorithm, which greatly reduces the optimization time. The dynamic XGBoost model ensures that the regression model accuracy near the optimum is relatively high, which is attributed to the update strategy. The error between the optimal value identified by the proposed algorithm and the theoretical value is only 0.52% after several objective function calls. Finally, the aerodynamic optimization algorithm is applied to the LS89 high-pressure turbine, and the total pressure loss is reduced by 13.16%. The sensitivity of each optimization feature to the objective function is determined, showing that the blade suction surface control point near the trailing edge has the greatest impact on aerodynamic performance.
Impact of Design Constraints on Noise and Emissions of Derivative Supersonic Engines
Authors: Prashanth Prakash , Voet Laurens J. A. , Speth Raymond L. , Sabnis Jayant S. , Tan Choon S. , Barrett Steven R. H.
Published: February 2023

The propulsion systems used in commercial supersonic transport (SST) aircraft, such as the Concorde, have used repurposed engines or derivative engines based on cores from existing donor engines rather than purpose-designed clean-sheet engines. A similar approach is currently being adopted in the development of new SSTs. Turbomachinery components and cooling mass flow rates in derivative engines are sized by the design cycle of the donor engine and constrain the design of the derivative engine cycle. Here, we identify the constraints imposed by the donor engines and quantify their impact on the specific fuel consumption (SFC), certification noise, and [Formula: see text] (oxides of nitrogen) emissions index [EI([Formula: see text])] relative to purpose-designed clean-sheet engines. We design and optimize a clean-sheet and derivative engine for a notional 55 metric ton SST proposed by NASA. A clean-sheet engine optimized for SFC results in an approximately 4.5% reduction in SFC, an approximately 2.5-fold increase in EI([Formula: see text]), and a 1.2 EPNdB increase in certification noise relative to the derivative engine. Applying a constraint on EI([Formula: see text]) to the clean-sheet engine results in an approximately 0.5% reduction in SFC relative to the derivative engine. The work provides a quantitative comparison of clean-sheet purpose-built engines and derivative engines from an environmental perspective that can inform policy makers as they develop updated environmental standards for civil supersonic aircraft.
Flame Dynamics in the Combustion Chamber of Hybrid Rocket Using Multiangle Chemiluminescence
Authors: Luo Jiaxiao , Zhang Zelin , Lin Xin , Wang Zezhong , Kun Wu , Zhou Gongxi , Zhang Senhao , Li Fei , Yu Xilong , Wu Jie
Published: February 2023

The flame dynamics in the combustion chamber of a hybrid rocket motor were visualized using novel chemiluminescence imaging. A multidirectional visualization system employing [Formula: see text] endoscopes generated images based on methylidyne chemiluminescence (CH*), with one endoscope in the precombustion chamber and two in the postcombustion chamber. Images were collected with a high-speed camera using a 1 ms exposure and a 1 kHz frame rate. Fuel grains having a helical or a conventional circular port structures were assessed, and combustion trials were conducted using a laboratory-scale hybrid rocket motor with oxygen as the oxidizer at mass flow rates from 10.43 to [Formula: see text]: equivalent to combustion chamber pressures ranging from 0.7 to 1.24 MPa. Flame structures were observed during the ignition, combustion, and shutdown stages; and the helical grain generated a larger, more intense flame zone. A proper orthogonal decomposition analysis showed that the helical grains also produced a greater degree of turbulence and stronger oscillations. These results confirm that a helical structure increases the flow turbulence and convective heat transfer in the combustion chamber. These effects lead to higher regression rates and better mixing efficiency that may, in turn, provide greater combustion efficiency at optimized oxidizer/fuel ratios.
On Improved Understanding of Airfoil Performance Evaluation Methods at Low Reynolds Numbers
Authors: Koning Witold J. F. , Romander Ethan A. , Cummings Haley V. , Perez Perez B. Natalia , Buning Pieter G.
Published: February 2023

Airfoil performance for the Eppler 387 airfoil at low Reynolds number ([Formula: see text] to 460,000) is studied numerically and compared to existing experimental data. Two- and three-dimensional unsteady laminar Navier–Stokes simulations are performed to evaluate the large-scale dynamics of the flow. All cases show laminar separation of the boundary layer followed by the shedding of large coherent vortices resulting in reattachment only observed in the mean flow, referred to as bubble flapping. Integrated aerodynamic coefficients, pressure distributions, and separation–reattachment locations are presented and compared to experimental data. Absolute averaged section lift and drag errors in the range [Formula: see text] to 300,000 are 5 and 7%, respectively, and good agreement of the pressure distributions is obtained. Laminar separation locations are predicted within 2%-chord, and turbulent reattachment is on average predicted within 5%-chord of the experimental values, which is improved to 3%-chord when updated experimental data are used. The work illustrates that bubble flapping, and the resulting mean airfoil performance, can be analyzed using laminar unsteady Navier–Stokes simulations, and that it does not necessitate external disturbances or three-dimensional instabilities. The shear layer transition over airfoils is found to be dominated by two-dimensional vortex shedding resulting in unsteady reattachment.
Design and Characterization of High-Lift Capabilities for Slotted, Natural-Laminar-Flow Airfoils
Authors: Ortiz-Melendez Hector D. , Long Ethan , Colletti Christopher R. , Toth George , Perkins Cody , Keely Kathryn , Ansell Phillip J. , Coder James G.
Published: February 2023

Morphing leading-edge shapes are of great interest for natural-laminar-flow airfoils operating in high lift as they can be designed to delay separation without any steps or gaps in the surface geometry. A computational study was performed to explore leading-edge configurations for a high-lift system featuring the S207, slotted, natural-laminar-flow airfoil, which was designed for commercial transport applications. Morphing technology was applied to mitigate abrupt wing-stall characteristics and further increase maximum lift. As a result, significantly higher lift coefficients were obtained. However, signs of wake bursting (i.e., off-body separation and narrow stall region in lift curves) were observed. The high-lift aft element’s position was optimized in a previous study for the S204, a slotted, natural-laminar-flow airfoil designed for business-jet applications. An optimization of S207’s aft element for high-lift is recommended. A constant-width slot between stowed and deployed positions allowed attached flow to be maintained across the aft element, which proved beneficial when combined with leading-edge morphing technology. The use of morphing technology was observed to produce superior high-lift performance over drooped leading edge, as the latter produced detrimental pressure peaks caused by the sharp curvature of the flap-like drooped leading edge’s upper surface that led to compressible stall.
Fluidic-Oscillator-Based Pulsed Jet Actuation on a Vertical Tail
Authors: Löffler Stephan , Weiss Julien
Published: February 2023

An industry-relevant vertical tail plane (VTP) model equipped with fluidic-oscillator-based pulsed jet actuators was tested with different active flow control (AFC) settings, rudder deflection, and sideslip angles at a chord Reynolds number of 1.3 million. In addition to pressure and force measurements, tuft visualizations and stereoscopic particle image velocimetry measurements were used to investigate AFC effects. With a total momentum coefficient of 1.5%, the control authority (lateral force) of the VTP was increased by a maximum of 34% when actuators were distributed along the rudder span. Additionally, flow control at dedicated positions on the rudder was investigated by using individual actuator segments. It was found that AFC is particularly effective at the position of the maximum load in the spanwise direction. The measurements also confirmed that local application of AFC actuators may simulate the effect of a boundary-layer fence. Finally, a comparison with existing results obtained with sweeping jet actuators shows that these two specific AFC implementations are most effective in different ranges of the momentum and the power coefficients.
Programmed Out-of-Plane Curvature to Enhance Multimodal Stiffness of Bending-Dominated Composite Lattices
Authors: Tiwari Pratik , Naskar Susmita , Mukhopadhyay Tanmoy
Published: February 2023

Conventional bending-dominated lattices exhibit less specific stiffness compared to stretching-dominated lattices while showing high specific energy absorption capacity. This paper aims to improve the specific stiffness of bending-dominated lattices by introducing elementary-level programmed curvature through a multilevel hierarchical framework. The influence of curvature in the elementary beams is investigated here on the effective in-plane and out-of-plane elastic properties of lattice materials. The beamlike cell walls with out-of-plane curvature are modeled based on three-dimensional degenerated shell finite elements. Subsequently, the beam deflections are integrated with unit cell level mechanics in an efficient semi-analytical framework to obtain the lattice-level effective elastic moduli. The numerical results reveal that the effective in-plane elastic moduli of lattices with curved isotropic cell walls can be significantly improved without altering the lattice-level relative density, while the effective out-of-plane elastic properties reduce due to the introduction of curvature. To address this issue, we further propose laminated composite cell walls with out-of-plane curvature based on the three-dimensional degenerated shell elements, which can lead to holistic improvements in the in-plane and out-of-plane effective elastic properties. The proposed curved composite lattice materials would enhance the specific stiffness of bending-dominated lattices to a significant extent, while maintaining their conventional multifunctional advantages.
Automatic Nonlinear Subspace Identification Using Clustering Judgment Based on Similarity Filtering
Authors: Zhu Rui , Jiang Dong , Marchesiello Stefano , Anastasio Dario , Zhang Dahai , Fei Qingguo
Published: February 2023

Accurately determining system order plays a vital role in system identification directly related to the accuracy of identification results, especially for nonlinear system identification. Due to the need for human subjective judgment, the traditional sequence determination method easily causes uncertainty in the results; and the phenomenon of the virtual mode or omission occurs. An automatic nonlinear subspace identification method is proposed to address the aforementioned problems. When the eigenvalue decomposition of the constructed Hankel matrix is performed, the calculation range of the modal order of the system is estimated. The similarity coefficient and distance function are introduced to cluster the identified modal results, the poles of the false modes are removed to obtain the cluster stabilization diagram, and the best order of the system is received. Then, the modal parameters and nonlinear coefficients are obtained. Simulation examples are carried out to verify the effectiveness and robustness of the proposed method. An experimental study is carried out on a multilayer building with nonlinear characteristics. Compared with the traditional stabilization graph, the accuracy of the automatic order determination proposed in this paper is proven.
Experimental and Analytical Study on the Liquid Film by Jet–Wall Impingement
Authors: Liu Chuansheng , Tang Chenglong , Ma Qingchen , Huang Zuohua , Zhang Peng , Zhang Feng
Published: February 2023

Liquid film cooling by jet–wall impingement on the combustor wall is commonly used in small rocket engines. The heat transfer mechanism inside the liquid film is closely related to the film flow. Therefore, we establish a comprehensive analytical model with reasonable assumptions for the liquid film flow by inclined jet–wall impingement, and we validate it through a series of experiments. It is found that the predicted liquid film dimensions agree well with the experimental results. As the impingement angle increases from 30 to 60 deg, the shape of the liquid film turns from an oval to a circle. With the increase of the impingement velocity from 7.8 to [Formula: see text], the width, length, and area of the liquid film increase. The wall roughness [Formula: see text] ranges from 6.3 to [Formula: see text], which shows negligible effects on the liquid film dimensions. As the surface tension increases from 36.03 to 67.13 mN/m and the viscosity increases from 1 to [Formula: see text], the dimensions of the liquid film decrease. The effect of viscosity is more significant than surface tension within the scope of this experiment. Finally, an empirical correlation for the three investigated film dimensional parameters is proposed.
Temperature Rise Characteristics and Experimental Study of Magnetorheological Dampers Under Different Excitations
Authors: Zhen Liang , Feng Yongbao , Han Xiaoxia , Zhang Zhenhua
Published: February 2023

The magnetorheological damper converts the mechanical energy of vibration into its own thermal energy, and the thermodynamic energy is expressed as the temperature rise. In this study, according to the principle of temperature rise, the temperature rise of the magnetorheological damper is established theoretical model by using the simplified one-dimensional heat transfer model of a fluid element and the lumped parameter method under the action of sine harmonic wave motion and triangular wave motion, as well as using the finite element software COMSOL to simulate the internal temperature fields of the damper. The results show that the temperature values of the damper are different, there are high-temperature areas and low-temperature areas, and the temperature rise mainly comes from the heating of the coil. The different frequency and amplitude of the excitation signal, as well as the input current, will affect the internal temperature of the damper. The temperature rise increases with the increase of input current, amplitude, and frequency, which is verified on the built testbench for the temperature rise characteristics. The change trend of the theoretical calculated value, the simulated value, and the tested value is consistent; and there is an error within the allowable range. By comparison, the temperature rise trend is basically the same for the three methods; but, when comparing with the application of sine harmonic wave motion, the temperature rise of the magnetorheological damper is 5°C higher than the triangular wave motion under the same operating condition.
THEORETICAL PROVISIONS OF JUSTIFICATION OF THE ESSENCE OF THE “BANK CREDIT MANAGEMENT” CATEGORY
Authors:   Chernihiv Polytechnic National University, Dubyna Maksym , Lobko Oleh ,   Chernihiv Polytechnic National University
Published: February 2023

Abstract. Banking business in today’s realities is one of the most dynamic effectively progressing spheres of the economy. In current conditions, a situation has developed in Ukraine in which the main activity of the bank, which can really provide a profit, is credit activity. However, the implementation of this activity is accompanied by significant risks. This, in turn, determines the importance of the formation of effective decision-making systems in banking institutions regarding the loans issuance to economic entities. The outlined causes the need to conduct new scientific research directed to the efficiency increase of the credit activity of banking institutions, ensuring the quality of credit management.Within the article, the essence of the “bank credit management” category is substantiated, which is carried out based on the approaches analysis to considering this definition formed in the scientific literature, the study of the content of such categories as “credit” and “management”. As a result, the author’s understanding of the content of the bank’s credit management is proposed, namely: bank credit management –a separate component of bank management, a complex system of methods, tools, rules and norms used by employees to carry out credit activities by a banking institution based on the established basic principles of its implementation, and ensure financial stability of the bank, rational use of available financial resources and receiving profit. Within the article, basic substantive characteristics of the specified category are singled out, the features of the credit management formation by various economic entities, including enterprises, which do not provide financial services, are analyzed.The results of the analysis of the conducted research made it possible to determine and describe the role of the bank’s credit management in the development of the banking activity, establish that this activity is leading from the point of view the formation of income and profit of these institutions in Ukraine.
INFORMATIONANDECONOMICSECURITY: LEVEL ASSESSMENT AND INTERCONNECTION
Authors:   National University «Yuri Kondratyuk Poltava Polytechnic», Bilko Stanislav
Published: February 2023

Abstract. The article is devoted to the study of a comprehensive assessment of the level of information security as a basis for timely and reasonable determination of measures to pre-vent and overcome the negative consequences in the event of potential risks and threats. It is substantiated that in the context of information and hybrid wars, strengthening information se-curity is a prerequisite for the protection of national economic interests. The formation of a security-oriented information environment, ensuring the security of state information re-sources, information with restricted access, in particular that circulating on the objects of eco-nomic information infrastructure is the basis of the national security of the country. The absence of a unified approach to assessing the level of information security is noted and the author's approach based on the use of qualitative indicator indicators of information security with the use of quantization, smoothing and normalization methods is proposed. It is proposed to define the following subindices of the integral indicator of information security: development of the state policy in the field of information security; monitoring and analysis of threats to the infor-mation environment; education and advanced training in the field of information security, in-cluding cyberspace; contribution to global information security, protection of digital services and basic services in cyberspace, electronic identification services, personal data protection; fight against cybercrime and military cyber operations. The results of the correlation and re-gression analysis made it possible to establish that information and economic security have the potential to provide synergistic effects. The necessity of ensuring the formation of a secu-rity-oriented information environment as a basis for the realization of national interests is sub-stantiated, which creates new opportunities for strengthening the security of the national econ-omy in the face of increasing influence of internal and external destabilizing factors
Sistem Informasi Administrasi Indra Music School Bandung berbasis Desktop
Authors: Andrijana Kusuma Kanggep , Ahmad Firdaus Eryan , Naufal Alman
Published: February 2023

Computer technology has developed very rapidly. Human activities and activities have been dominated by computers. Work done by humans manually has turned to a computerized system. Indra Music School Bandung needs an information system to support and provide better service to its students. Then arranged about the teaching information system. Indra Music School Bandung is engaged in teaching music. The system used is still done manually from student absences, storing teaching and learning data and storing student progress data. It is necessary to develop a teaching computerized system with the aim of improving services to students, facilitating the administration in storing data and being able to achieve effectiveness in supporting teaching activities at Indra Music School Bandung.
Identifying Optimal Operating Envelope in Horizontal Wells Producing from Dual Permeability Media
Authors: Alrumaih Abdulrahman W. , Kanu Kingsley , Sakhin Zahra
Published: February 2023

In this paper, we present an integrated workflow utilizing a numerical model to identify optimal operating envelope for horizontal wells producing from dual permeability media. A synthetic dual permeability numerical model comprised of critical components namely: fracture and matrix permeabilities, matrix-fracture conductivity (shape factor), and fracture distribution based on Discrete Fracture Network (DFN) scheme was built. In addition, two horizontal producers completed with Inflow-Control – Devices (ICDs) and as open-hole respectively, are also connected to the model. Rigorous sensitivity analysis is implemented on these key parameters using the dynamic model under Equalspacing sampling scheme with well oil rate as the objective function. Range of values on each variable are typical for naturally fractured reservoirs. In addition, detailed sensitivity on ICD parameters such as flow resistance ratings are performed. Results from the analysis are presented in cumulative probability function identifying most likely, pessimistic and optimistic values.

Among all the variables, Matrix-fracture transmissibility has most impact. Unfortunately, it is often neglected when designing horizontal wells in dual permeability reservoirs. Current practice pays most attention on permeability contrast lack of consensus in the industry on best technique for its estimation. Most common methodologies applied are Kazemi and Warren-Roots. Nevertheless, it plays a critical role in describing dual permeability subsurface flow mechanism. Most significantly, it is widely acknowledged that beaning up choke sizes enhances production performance of wells connected to dual permeability. However, in this study, we have been able to establish operating limits for this phenomenon.

Matrix-fracture transmissibility could significantly influence a producer, which has not intersected high permeability streaks. Our study clearly demonstrates this observation using high-resolution dual permeability dynamic model. In addition, by performing multi-variate characterization, we establish operating envelope for optimizing well production performance in dual media systems through choke size settings.
Risk Mitigation Strategy Improves Drilling Performance with Geomechanical Modelling in Horizontal Wells
Authors: Li Tanglv , Li Jianhai , Cao Jixiang , Wang Jinxi , Gong Chen , Deng Yantao
Published: February 2023

The problem of wellbore instability is a worldwide technical problem in the field of the drilling engineering and one of the core problems for the safe and efficient drilling. After the drill bit drills the formation and a borehole is formed, the drilling fluid column pressure replaces the support provided by the drilled rock stratum, upsetting the original stress balance of the formation, and causing the stress redistribution of the rock around the borehole. If the redistributed stress exceeds the maximum load that the rock can bear, it will lead to wellbore instability. At the same time, the invasion of the drilling fluid filtrate into the formation will cause an increase in the formation pore pressure and a decrease in rock strength, further aggravating the instability of the wellbore. In tight gas development, the particularity of the drilling of the long-horizontal wells, during which the unstable bedded sandstone is taken as the target layer, the distribution of the secondary stress around horizontal wells, which is very different from that of vertical wells, the complex stress environment of tight gas reservoirs, and the well-developed bedding/fractures all increase the risk of wellbore collapse and instability. Based on the pore elasticity and single structural plane strength theory, this paper establishes a mechanical analysis model for the wellbore stability of horizontal wells in layered shale to analyze the effects of bedding plane occurrence (strike, dip angle), wellbore trajectory (wellbore orientation), and weakening of bedding plane strength on wellbore stability of horizontal wells. Besides, this paper establishes a three-dimensional geomechanical model of Zhongqian 1 block based on the geomechanical modeling technology to precisely characterize the distribution characteristics of mechanical parameters in three-dimensional space to provide technical support for the optimization of horizontal well drilling plan.
Structural Reliability Analysis and Quantitative Risk Assessment for Optimizing Cost of Offshore Structural Integrity Management and Life Extension Programme without Air Diving Operation
Authors: Katanyoowongchareon Somkiat , Danthainum Athip , Chattratichart Tanasit , Sriparagul Jirapol , Kongchang Adisak , Ruamchomrat Napath , Suankem Suratchata
Published: February 2023

Offshore platforms in Gulf of Thailand have been aging and reaching their end of service life. To safely operate in aging platforms beyond their original intended service life, all possible operation risks need to be assessed through design review, condition assessment, inspection strategy and technique for the platform life extension stage. Qualitative or Semi-quantitative risk assessment was generally utilized by adopting scoring rule based on the condition assessment through inspection data/anomalies. A general subsea inspection campaign requested a costly additional air diving campaign for ACFM for joints with low fatigue life without a consideration of past inspection results. In practice, the routine inspection should be arranged in such a way that the operation risk meets the as-low-as practically possible (ALARP) criteria and yet minimize the cost, time and resources required for inspection. A quantitative risk assessment (QRA) and structural reliability analysis (SRA) are applied within PTTEP to evaluate and predict platform's risk development through time dependent probability of system failure. Inspection strategy including interval (when), locations (where), and suitable equipment and technique (how) are quantitatively incorporated into a mathematical model. The system probability of failure incorporating the system degradation is evaluated and inspection is triggered when the risk exceeds the allowable threshold. A complementary statistical decision model to evaluate the suitable inspection interval considered cost of failure, loss of production, and inspection is also employed. Results of quantitative method shows that the inspection interval can be prolonged, particularly, for well-designed and well-maintained platforms with reducing demand of additional air diving campaign. For most platform with relatively low to moderate consequences of failure, the inspection interval can be extended up until 10 years with routine general visual inspection (GVI), Flooded Member Detection (FMD) operated by remotely operated vehicle (ROV), provided that no significant anomalies are reported during the entire platform life cycle.

In Summary, the approaches minimize the demand for additional air diving operation leading a reduction in additional cost, operational risk, and carbon footprint at least 250MT. The offshore structural integrity management and life extension programme for platform after service life by QRA is considered as new leveraged paradigm and delivers the cutting-edge integrity management programme leading to the most optimized operational cost with philosophy of safety and sustainability.
A Successful Activator Flooding Pilot Test in Offshore Oilfield: A Comprehensive Evaluation and Interpretation
Authors: Jin Yi , Zhang Jian , Tang Engao , Wang Xudong , Liu Yuyang , Zhou Wensheng , Wei Zhijie
Published: February 2023

Oil reserves with oil viscosity above 150 mPa·s account for a large proportion of the Bohai Oilfield. However, due to the low mobility of heavy oil, and low sweep efficiency of injected fluid, the recovery factor of heavy oil is always low. A new amphiphilic polymer (activator), which can effectively disassemble the accumulation of asphaltene molecular layer of heavy oil, thus reducing oil viscosity has been developed in the lab and applied for two injection wells in Bohai Oilfield for a pilot trial.

In this paper, the pilot trial of heavy-oil activator flooding (HAF) is comprehensively evaluated in both injectivity, production, and interwell connectivity analyses. The apparent injectivity index, Hall plot analysis, injection profile measurement for different layers, and PI test methods are applied to study the seepage resistance build-up effect at injection wells. Waterflooding characteristic curve method is implemented for history matching and oil incremental analysis. The interwell connectivity between wells is characterized by the Capacitance Resistance model (CRM).

The injection trials showed great seepage resistance build-up effects at two activator injectors. There are apparent deviations in Hall plots after the activator injection. Activator flooding enables uniform water injection profiles for different layers. The PI tests show that the pressure drop speeds get lowered during the injection period. As for the oil incremental effect evaluation, the theoretical waterflooding characteristic curve function gives an estimation of the incremental oil production to be 1.77×104 m3 during the evaluation period. CRM analysis indicates that the connectivity between injector I2 and producer P4 is higher than that of other wells, and the time lag of getting a response by the activator fluid is smaller than other wells, which is an indication of potential fluid channeling in the flow path. It is validated by the high concentration of produced agent from P4 during HAF.

The successful implementation of the activator flooding pilot trial proves that the lab results of amphiphilic polymers can be scaled up to field scale and it plays an important role in the de-risking of full-field implementation. Besides, it shed light upon the effective displacement of heavy oil with a viscosity greater than 150 mPa·s in offshore reservoirs by amphiphilic polymers.
Research on the Adaptability of SP Flooding in Sand-Gravel Mixture Reservoir Based on the Inverted Seven-Spot Well Pattern
Authors: Tang Xuechen , Li Yiqiang , Cao Jinxin , Liu Zheyu , Chen Xin , Liu Li , Bo Jiangwei
Published: February 2023

As one of the leading technologies for chemical enhanced oil recovery (cEOR), surfactant-polymer (SP) flooding technology has drawn the attention of petroleum scientists and engineers for many years. However, most of its application scenarios are based on the five-spot well pattern. Rarely reported is its EOR potential in an inverted seven-spot well pattern. Based on the physical properties of Karamay Oilfield in China, this paper studied the adaptability of the SP system in the inverted seven-spot well pattern. Firstly, the numerical simulation method and the single-core flooding experiment were used to compare the seepage intensities of the two well patterns and the EOR ability of the SP system under different seepage intensities. Then, the migration law and the oil displacement effect of the SP system under the conditions of sand-gravel mixture were evaluated. Finally, the EOR ability under different injection strategies in the well patterns was evaluated. The results show that the inverted seven-spot well pattern shows a weak swept state, accounting for 61% of the whole region. Appropriately increasing the viscosity and slug size of the SP system improves the oil production of the low-permeability conglomerate layer. Step-down viscosity injection can further enlarge the sweep range of injection fluid and enhance oil recovery compared to constant viscosity injection. Compared with the five-spot well pattern, the swept area of the SP system in the inverted seven-spot well pattern is larger while the strength is weaker. The injection and production wells should be reasonably arranged when the well pattern is converted to efficiently recover the remaining oil and residual oil that are not recovered in the five-spot well pattern by utilizing the inverted seven-spot well pattern characteristics.
Understanding the Complicated Fracture Network in a Fractured Granite Reservoir Using the Borehole Image and Geochemical Log, Case Study from Songliao Basin
Authors: Yan Weihe , Zhou Cong , Wang Yuhua , Jiang Baoyan , Liu Bo , Wu Jinlong , Liu Xunqi , Lu Qingzhi , Paramatikul Ronarong , My Dung Doan Thi
Published: February 2023

Granite basement reservoir has become a very important exploration target in Songliao Basin of North-east China. Several exploration gas wells were drilled in the study area, and it shows strong heterogeneity and complexity in reservoir properties. Since it is very difficult to perform accurate formation evaluation in fractured granite reservoir using the conventional open-hole logs, the advanced wireline logging such as borehole resistivity image and geochemical logs were acquired to understand the impact of the fractures on the producibility in the tight granite reservoir. The objective of this research is to understand the complicated natural fracture system in the tight granite reservoir.

The high-resolution borehole resistivity image logs could provide abundant information to evaluate the fracture distribution, direction, and intensity. It can also reveal the secondary pores and dissolution enhanced features in the granite basement reservoir. The high-definition spectroscope logs provide significant information for geological description and evaluation of the downhole formations. One parameter "K/Na (potassium/sodium) ratio" was developed to differentiate the composition of the minerals in the formation. It was found that the intervals with high K/Na ratio have higher fracture apertures than other intervals in the case. The reservoir quality is controlled by fracture density and secondary porosity. Different sets of nature fractures have a different angle range or strike, and it will create a complex natural fracture network. The fracture zones with complex fracture network have suffered stronger weathering process than the zones with simple fracture network.

The case study shows that the high porosity zone with complex natural fracture network has strong dissolution. The K/Na ratio from geochemical log also have clear anomaly in that zone. It indicates that there has strong chemical weathering process in that zone which has high K/Na ratio than other zones. These zones have complex fractures network and strong dissolution than other zones. Better understanding the controlling factors of the fractured granite reservoir could be helpful for fracturing design and well positioning.

The integration of borehole image and geochemical log in the fractured granite reservoir was proven to be effective method in this case study. It could be used as a reference for similar reservoir fracture evaluation.
CO2 Capturing and Storage From Oil Wells
Authors: Al-Aklubi Sultan , Al-Rubaii Mohammad
Published: February 2023

The world is currently facing one of the most critical challenges in the Earth’s history which is global warming. The major cause of global warming and climate change problems is the carbon dioxide emissions. This novel study addresses the concepts and design precautions for a proposed in-situ electricity generation project.

The main goal of the study is to reduce the environmental pollution due to the combustion of fossil fuels and emitting carbon dioxide. This reduction will be attained through a smart gas well design and completions. The design is based on in-situ combustion for a gas flow in a downhole combustion chamber. Oxy-fuel combustion technique is the proposed combustion technique due to the ease of CO2 separation in this process. The proper well design will be analogous to the wells used for in-situ oil combustion to handle the high released temperature. Power generation design will combine the fundamentals of geothermal energy deployment for electricity generation. Finally, the produced CO2 from the combustion process will be reinjected downhole into an underground geological structure after being compressed and transferred to the supercritical phase. This process eliminates the CO2 production to the surface and hence reduce the environmental pollution.
Real-Time Downhole Monitoring Using DAS and DTS: A New Technology for Leak Detection and Well Integrity
Authors: Cherubini Aurelien , Richard Simon , Jestin Camille , Calbris Gaëtan , Lanticq Vincent
Published: February 2023

Distributed Acoustic Sensing (DAS) and Distributed Temperature Sensing (DTS) measurements are technologies which are adding some benefits in the aim to replace or complete traditional logging measurements like noise logging tools (NLT) or production logging tools (PLT). The aim of well integrity interventions using distributed fiber optic sensing (DFOS) is to significantly reduce the duration and the cost of these operations, and to provide additional information in comparison to traditional logging tool. The combination of DAS and DTS can offer both qualitative and quantitative information regarding fluid dynamics in the context of well integrity investigation, as the flow characteristics (intensity of turbulences).

In this study, we will investigate different failure patterns occurring on the well completion, as the production tubing or packers. On the first hand, we will see that the combination of DAS and DTS provides complementary information regarding leaks characterization. On the other hand, we will investigate the monitoring of temperature gradient (DTGS for Distributed Temperature Gradient Sensing) using DAS by the integration of low frequency acoustic signal (< 1 Hz).
Phytochemical Studies and Identification of Bioactive Compounds using High-performance Liquid Chromatography and Gas Chromatography- Mass Spectrometry of Leaf Extract of Jatropha curcas
Authors: Kichenamourty Gayathiri . , Vellapandian Chitra .
Published: February 2023

Chronic, recurring, and remitting inflammatory disease with an unknown cause is inflammatory bowel disease (IBD). It is a condition that affects people throughout their lives and has many consequences because it is clinically common. Numerous risk factors are still unknown, and the pathophysiology of IBD is still not fully understood. There are a variety of side effects associated with conventional ulcerative colitis treatment. Globally, there is a rise in the use of herbal therapy for IBD. The medicinal plant Jatropha curcas (L.) belongs to the Euphorbiaceae family. It is a biofuel plant with a few pharmacological effects that have been researched. The study’s purpose was to discover and investigate the bioactive components in an ethanolic extract of J. curcas. The leaves of L. J. curcas were gathered, shade dried, crushed up, and gradually extracted with ethanol using the soxhlet percolation method. By using fourier-transform infrared spectroscopy (FTIR) and high-performance liquid chromatography (HPLC), the phytoconstituents in the Jatropha leaf extract were confirmed. Along with the interpretation of mass spectra, the isolated chemicals were identified by contrasting their peak areas and retention times. Due to the discovery of possible, bioactive components as a result of the current inquiry, we are now able to investigate biological activity. After that, gas chromatography-mass spectrometry (GC-MS) was used to analyze the crude extracts. A large variety of secondary metabolites were detected in the extracts’ profile, which was then spectroscopically described. The presence of phytoconstituents, including flavonoids, tannins, and triterpenoids significantly reduces internal inflammation and lessens damage to the intestinal mucosa. Herbal treatments work through a variety of processes, including immunological control and antioxidant activities.
Evaluation of Bioactive Potential of the Digera muricata Mart
Authors: Tomer Nalini . , Ali Mohammad Irfan , Moin Sarmad .
Published: February 2023

Digera muricata (L.) mart (Amaranthaceae) is a promising medicinal plant used as a prophylactic, antioxidant, anthelmintic, antimicrobial, allelopathic, and antidiabetic. The present study assesses the quantification of primary and secondary metabolites along with the antimicrobial potential of D. muricata. Qualitative and quantitative phytochemical analysis was undertaken to evaluate secondary metabolites extracted from leaf extracts of D. muricata by using standard methods. The antibacterial and antifungal potential was studied by using the disc diffusion method. A (gas chromatography-mass spectrometry) (GC–MS) study was carried out to recognize the bioactive molecules in the active fraction. D. muricata contained carbohydrates, proteins, steroids, amino acids, cardiac glycosides, coumarin, polyphenol, alkaloids, saponin, tannin, and flavonoids. Results also indicate that ethyl acetate extracts of D. muricata showed significant antimicrobial potential against Streptococcus agalactiae (ATCC13813), Klebsiella pneumoniae (MTCC432), Escherichia coli (MTCC730), Streptococcus pyogenes (MTCC1924), Macrophomina phaseolina, and Candida albicans (MTCC7315). These findings showed that the ethyl acetate extract of D. muricata confined bioactive molecules of therapeutic rank with significant antibacterial and antifungal activity.
A Good Result of Cardiopulmonary Resuscitation Following Colonic Segment Interposition with Vascular Supercharge
Authors:   Department of Plastic Surgery, China Medical University Hospital (CMUH), Taichung, Taiwan, KY Cheng , HC Chen ,   Department of Plastic Surgery, China Medical University Hospital (CMUH), Taichung, Taiwan
Published: February 2023

A 70-year-old man who underwent surgical excision of an esophageal leiomyoma developed esophageal leak and underwent esophagectomy. Colonic segment interposition was performed to address the esophageal defect. Cardiopulmonary resuscitation (CPR) was subsequently performed for desaturation due to pulmonary atelectasis; spontaneous circulation resumed without indication of contrast leakage or necrosis. Redundancy of the esophagus in the neck occurred due to migration of the colon segment during CPR. We shortened the colonic segment, which improved swallowing function. Here we report the first case of a positive outcome of cervical herniation of a colon graft due to CPR after a colonic interposition procedure.
Dissecting Intramyocardial Hematoma Following Mitral Valve Repair
Authors:   Department of Outcomes Research, Cleveland Clinic, Cleveland, OH, USA, EK Yalcin , PD Villiers ,   Department of Cardiothoracic Anesthesiology, Cleveland Clinic, Cleveland, OH, USA, P Wierup ,   Department of Cardiothoracic Surgery, Lund University, Lund, Sweden, A Alfirevic ,   Department of Outcomes Research, Cleveland Clinic, Cleveland, OH, USA
Published: February 2023

A 67-year-old male patient with a severe mitralinsufficiency presented for reoperation after a failed Mitral Valve (MV) repair. The prior annuloplasty ring was removed and a new 32-mm fully rigid ring was inserted with the affixation of artificial chords to the anterior MV leaflet. Initial post-bypass transesophageal echocardiographic examination demonstratedresolution of mitral regurgitation and normal biventricular function (Figure 1), RV=Right Ventricle, LV=Left Ventricle).
Unilateral Isolated Inferior Rectus Palsy: A Rare Presentation of Ocular Myasthenia Gravis
Authors:   Department of Ophthalmology, Army Hospital Research & Referral, India, Y Yadav , S Dhar ,   Department of Ophthalmology, Army Hospital Research & Referral, India, P Singh ,   Department of Ophthalmology, Army Hospital Research & Referral, India, T Mohapatra ,   Department of Ophthalmology, Army Hospital Research & Referral, India, R Gupta ,   Department of Ophthalmology, Army Hospital Research & Referral, India, SK Mishra ,   Department of Ophthalmology, Army Hospital Research & Referral, India
Published: February 2023

Ocular Myasthenia Gravis with unilateral isolated Inferior Rectus palsy and no ptosis is rarely encountered. We present a case of 25-year-old male with sudden onset binocular diplopia and no features of ptosis. Deviations in primary gaze were 3-8 Prism Dioptre (PD) with left hypertropia. Right and left head tilt deviations were 5PD and 3PD left hypertropia respectively with increase in hypertropia in left gazes. Acetylcholine receptor binding antibodies were found to be raised. Repetitive Nerve Stimulation showed decreased amplitude. Patient was managed with Oral Pyridostigmine with excellent symptomatic relief and drug tolerance. No features of Myasthenia Gravis (Systemic or Ocular) were noted on follow-up.