bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Study on the Effect of Streamwise Groove Suction on Upper Endwall on a Transonic Sectorial Compressor Cascade with Inlet Guide Vane
Authors:   Dalian Maritime University, Liang Ruixing , Lu Huawei ,   Dalian Maritime University
Published: February 2024

The research object of this paper is transonic sector compressor. In order to explore the influence of the boundary layer suction on the aerodynamic performance and flow field structure of the transonic sector compressor, the numerical simulation method was used to study the upper endwall’s suction to the groove boundary layer of the compressor. Comparing the prototype sector cascade and each improvement of different suction schemes, it can be found that the upper endwall boundary layer suction has a significant effect on the suppression of the upper corner separation, which can reduce the loss and improve the pressure expansion capability. The suction effect is well,with the suction groove position set near the separation start point of the corner zone, and the total pressure loss of the cascade is reduced more.
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Authors:   School of Power and Energy, Northwestern Polytechnical University, withdrawn withdrawn , withdrawn withdrawn ,   School of Power and Energy, Northwestern Polytechnical University, withdrawn withdrawn ,   School of Power and Energy, Northwestern Polytechnical University
Published: February 2024

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Influence of inlet and outlet geometrical angle deviations on the aerodynamic performance of compressor airfoil
Authors:   Xi’an Jiaotong University, Li Shenzhen , Sun Enbo ,   Xi’an Jiaotong University, Long Yuhan ,   Xi’an Jiaotong University, Wu Yun ,   Airforce Engineer University Xi’an Jiaotong University, Zhang Haideng ,   Airforce Engineering University
Published: February 2024

The geometric deviation of blades significantly impacts the performance of modern highly loaded compressors. Therefore, attention should be paid to the influence of the geometric deviation of blades on the aerodynamic performance of compressors. This paper intends to investigate the influence of inlet/out geometrical angle deviations on the aerodynamic performance of a typical subsonic controlled diffusion compressor airfoil. The aerodynamic performances of the compressor airfoil with different types of inlet/outlet geometrical angle deviations are simulated and the mechanism behind the variations of the total pressure loss as well as outlet deviation angle are analyzed. The blade becomes more sensitive to angle geometric deviation as the incidence angle increases, and the impact of angle deviation on aerodynamic performance is greater in the negative incidence angle range than in the positive ones. However, the influence of geometrical angle deviations at the inlet on blade aerodynamic performance is greater than that at the outlet. Geometrical angle deviation at the inlet alters the peak velocity and reverse pressure gradient during the acceleration process of depressurization at the suction surface of the blade, whereas geometrical angle deviation at the outlet directly changes the flow direction with geometric variation, and this has an impact on aerodynamic performance.
Acceleration of Large-Eddy Simulation Using Harmonic Balance Method for Unsteady Flows with Low Non-dimensional Frequency
Authors:   Department of Aeronautics and Astronautics, The University of Tokyo, Iwamoto Yuma , Teramoto Susumu ,   Department of Aeronautics and Astronautics, The University of Tokyo, Okamoto Koji ,   Department of Advanced Energy, The University of Tokyo
Published: February 2024

Harmonic Balanced Large-Eddy Simulation(HB-LES) is proposed for the efficient high-fidelity simulation of the unsteady flows with low non-dimensional frequency. Harmonic balance method for unsteady RANS simulation is originally introduced to large-eddy simulation, utilizing the difference in timescales between the period flow and the turbulent fluctuations. Periodic flow and turbulent fluctuation are computed without disregarding their nonlinear mutual interference by iterating short-time large-eddy simulation and harmonic balance method. Evaluation computations of HB-LES are performed for Srokes Boundary Layer at Reynolds number of 1790 and pitching NACA0012 airfoil. The accuracy and computational efficiency of the HB-LES are discussed by comparing with the conventional large-eddy simulation and experimental results.
Aeroacoustic Performance Comparison Between a Small Contra-Rotating Fan and the Series Operation of Two Fans
Authors:   Department of Mechanical Engineering, The University of Hong Kong, Xu Tianyu , Yang Dangguo ,   High-Speed Aerodynamics Institute, China Aerodynamics Research and Development Center, Dong* Bin ,   High-Speed Aerodynamics Institute, China Aerodynamics Research and Development Center, Ning Ronghui ,   High-Speed Aerodynamics Institute, China Aerodynamics Research and Development Center
Published: February 2024

Small axial flow fans are frequently used as air coolers or ventilators, and their aeroacoustic mechanism is similar to those found in larger machinery like aeroengines. Currently, there is a growing interest in adopting contra-rotation due to its inherent aerodynamic advantages. However, acoustically, contra-rotating (CR) fans radiate additional interaction noise, which decreases the sound quality and may cause extra annoyance. In this work, a sample CR fan is designed using simple radial equilibrium theory supplemented by three-dimensional steady-flow simulations, and its aeroacoustic performance is compared with that of two fans in a series. In general, the designed CR fan can produce a larger volumetric flow rate as well as a higher total pressure rise at lower rotational speeds compared with the series design. An acoustic comparison of specific noise levels shows that, in the flow rate range from the design point to higher flow rates, the CR fan is quieter. However, when the CR fan stalls in the lower flow rate region, its specific noise level is higher than that of the fan series. In addition, from the noise spectrum, the tonal noise power of the CR fan is less than that of the fan series.
A Novel Performance Adaptation Method For Aero-Engine Matching Us-ing Adaptation Factor Surface
Authors:   Department of Aeronautics & Astronautics, Fudan University, Wang Ye , Wang Xizhen ,   Department of Aeronautics & Astronautics, Fudan University, Wang Zepeng ,   Department of Aeronautics & Astronautics, Fudan University, Zhao Bokun ,   Department of Aeronautics & Astronautics, Fudan University, Zhaoa* Yongjun ,   Department of Aeronautics & Astronautics, Fudan University
Published: February 2024

High-fidelity performance modeling is crucial for the development of aero-engine digital twin technology. The accuracy of component-level models heavily relies on the precision of characteristic maps, and inaccuracies in these maps can cause significant deviations between predicted and actual engine performance. A novel method of aero-engine performance adaptation based on adaptation factor surfaces is proposed, which aims to provide a performance matching method for aero-engines with a wide operating range. To improve the convergence and stability of the solution, a hybrid algorithm is proposed that fuses model and measured data to calculate the adaptation factor at the operating points. The modification of the characteristic maps is achieved in both directions by means of adaptive factor surfaces. The method is validated by simulating two engines with distinct maps, and the results show that the method significantly improves the model accuracy at the component level under widely varying operating conditions, taking into account the multidimensional aspects of the maps and the differences between the real engine and the model. The proposed approach has the potential to improve the accuracy and efficiency of digital twin technology for aero-engines.
Numerical Simulation and Experimental Validation of Tip Leakage Vortex Breakdown under Large Clearance
Authors:   Northwestern Polytechnical University, Qian Kun , Li Litao ,   Northwestern Polytechnical University, Wu Yanhui ,   Northwestern Polytechnical University, Xue Yapeng ,   Northwestern Polytechnical University
Published: February 2024

The present study aims to enhance the comprehension of the flow field near the casing of an isolated rotor in a small-scale high-speed axial flow compressor. To achieve this objective, steady three-dimensional viscous flow calculations are employed to obtain flow fields under different operational conditions. To validate the accuracy of the computations, a comparison is made between the numerical results and existing measured data, revealing a favorable agreement. Then, using experiment measurements and numerical simulation, the casing pressure signals and steady flowfields at different operation points are analyzed in detail. The frequency spectrum shows that a high-amplitude region, which covering the passage of tip clearance and a bandwidth around 0.5BPF, occurs at peak efficiency condition. In addition, as the mass flow rate is further decreased, the high-amplitude region becomes more intense and the area moves upstream. Numerical simulation results explains the flow phenomena observed in experiments. In core area of the tip leakage vortex, the swirl parameter turns from negative to positive at the peak efficiency point, indicating that the leakage vortex breakdown. During the process of gradually approaching the steady calculate boundary point, the vortex breakdown results in the low-energy fluid accumulating on the casing wall, which causes a sudden growth of the casing wall boundary layer having a large blockage effect. A low-velocity region develops along the tip clearance vortex due to the vortex “breakdown”. Compared with the vortex external, the different colors of helix angle in vortex core shows opposite rotation direction.
1D analytic and numerical analysis of thin film heat transfer gauges and infra-red cameras in non-planar applications
Authors:   University of Oxford, Baker Mark , Rosic Budimir ,   University of Oxford
Published: February 2024

The impulse response method is widely used for heat transfer analysis in turbomachinery applications. Traditionally, the 1D method assumes a: linear time invariant, isotropic, semi-infinite block with planar surfaces and does not accurately model the true geometric behaviour. This paper evaluates the error introduced by the planar assumption and outlines the required modifications for accurate freeform surface analysis. Adapted cylindrical basis functions are defined for the impulse response method and used to evaluate the impact of the 1D planar assumption. The analytic solutions for both convex and concave surfaces are presented. A penta-diagonal algorithm, for a modified numerical Crank-Nicolson scheme, is also evaluated for fast stable implementation of curved geometry simulation. The scheme shows comparable performance to the impulse response, whilst removing the requirement for linear time invariance. The new methods are demonstrated in the case of aerothermal analysis for heat transfer in a turbine nozzle guide vane. A 3D ANSYS simulation is used as a benchmark and further highlights the importance of the curvature effects. The methods are extended using curvature mapping for infrared camera data, enabling direct 3D thermal simulation or the fast calculation of freeform curvature. This paper defines the methodology to analyse heat transfer measurements on non-planar geometry.
In-situ performance of axial flow fan for air-cooled condensers
Authors:   Dept. of Mechanical and Aerospace Engineering, Sapienza University of Rome, Corsini Alessandro , van der Spuy Johan ,   Dept. of Mechanical and Mechatronic Engineering, Stellenbosh University, Delibra Giovanni ,   Dept. of Mechanical and Aerospace Engineering, Sapienza University of Rome, Tieghi Lorenzo ,   Dept. of Mechanical and Aerospace Engineering, Sapienza University of Rome
Published: February 2024

Here we present a study on a fan for air-cooled condensers installed in Stellenbosh University test rig. It is a 7.3m diameter fan operated at 151 rpm and installed in a facility that, due to the presence of a channel below the structure and nearby buildings naturally operate with non-uniform inflow. This rises concerns about the inflow conditions that the fan can experience, leading to the present investigation to quantify possible disuniformities at the fan inlet. For this reasons several flow conditions are analysed to address this issue along the fan curve, providing a comparison with respect to measured (electric) power. Also the manuscript address how the flow develops downstream of the fan, to characterize the wake velocity defect at the inlet of the ACC heat exchanger.
Experimental and Numerical Study on Cooling Characteristic of Modelled Matrix Cooling Channels for Turbine Blades
Authors:   Harbin Engineering University, Zhou Xu , Zhang Yuxuan ,   Harbin Engineering University, Li Tao ,   Harbin Ship Boiler Turbine Research Institute, Han Rui ,   Harbin Engineering University, Dong Ping ,   Harbin Engineering University, Yu Zijie ,   Harbin Engineering University
Published: February 2024

The staggered-rib cooling structure is an enhanced heat transfer structure for internal cooling of turbine blades. In this paper, the flow and heat transfer of two modeled matrix channel structures inside a gas turbine blade is investigated experimentally and numerically. The detailed heat transfer distribution on the main surface was obtained experimentally in a wind tunnel using the steady-state liquid crystal technique. Based on the channel inlet hydraulic diameter, the experiments were performed in the Reynolds number range of 15968 to 58549.Then the Nusselt number distributions were obtained by preparing a computer program based on the steady-state heat transfer equation. The experimental results were used to calibrate the numerical solutions obtained by computational fluid dynamics methods. In the numerical simulations, the flow and heat transfer characteristics of converging matrix structure and non-converging matrix structure are investigated respectively. Numerical results showed that the velocity of cooling gas decreases significantly due to the sidewall turnings, resulting in a significant reduction of heat transfer along the path as well as a large pressure drop. At the same Reynolds number, the friction factor, the Nusselt number ratio and the thermal performance factor of non-converging matrix structure are higher than those of converging matrix structure, but the distribution of converging structure is more uniform. Both the Nusselt number ratio and the thermal performance factor increase with increasing Reynolds number, while the friction factor decreases and then increases with increasing Reynolds number.
Study on the mission economy of hybrid and electric flying cars
Authors:   School of Vehicle and Mobility Tsinghua University, Li Weifeng , Qian* Yuping ,   School of Vehicle and Mobility Tsinghua University, Qiang Xuankai ,   School of Vehicle and Mobility Tsinghua University, Zhang Yangjun ,   School of Vehicle and Mobility Tsinghua University
Published: February 2024

Flying cars are significant to future three-dimensional(3D) transportation. Pure-electric power possesses environmental-friendliness and low noise, which are suitable for urban air mobility (UAM). The hybrid power can achieve rapid power switching between vertical take-off and landing (VTOL) and cruising, and can easily meet the energy demand of long-range mission, making it suitable for intercity commuting. However, the high fidelity models of the power propulsion system are still lack, so does the quantitative research on the impact of flight mission parameters on the installed configuration and energy economy indicators of pure electric and hybrid power. The application scenarios have not been clearly distinguished. Firstly, this paper gives a flight mission profile that combines VTOL with climb and decent. Then, the installation performance requirements of batteries energy and power density are discussed. Afterwards, an optimization method for the installation configuration of pure electric and hybrid power systems that minimize the mission economy is progressed. The effects of different VTOL heights, ranges, and maximum take-off mass (MTOM) on mission economy for pure electric and hybrid flying cars are analysed. It is found that when VTOL height is 120m, the maximum range of pure electric flying vehicles is 180km. The mission economy of hybrid flying cars will be better than pure electric ones after 120km. As the range grow, the payload of pure electric flying cars decreases rapidly. The hybrid flying cars can maintain the payload of 30% MTOM, which present the mission economy of 0.003 RMB/kg km.
Analysis of unsteady tip leakage flow in an axial compressor rotor using dynamic mode decomposition
Authors:   School of Energy and Power Engineering, Beihang University National Key Laboratory of Science and Technology on Aero-Engine Aero- Thermodynamics, Beihang University, Wei Xindi , Hou Jiexuan ,   School of Energy and Power Engineering, Beihang University National Key Laboratory of Science and Technology on Aero-Engine Aero- Thermodynamics, Beihang University, Tang Yumeng ,   School of Energy and Power Engineering, Beihang University National Key Laboratory of Science and Technology on Aero-Engine Aero- Thermodynamics, Beihang University, Liu* Yangwei ,   School of Energy and Power Engineering, Beihang University National Key Laboratory of Science and Technology on Aero-Engine Aero- Thermodynamics, Beihang University
Published: February 2024

Tip leakage flow (TLF) is an important flow structure in the compressor, and it has a significant effect on the efficiency and stability of the compressor. In our study, dynamic mode decomposition (DMD) is used to study the spatiotemporal flow structure of the tip leakage flow in a compressor rotor. The high-fidelity flow field calculated via the delayed-detached eddy simulation (DDES) of an axial compressor rotor is used as the input dataset for the DMD algorithm. The results show that the unsteady motion of the tip leakage vortex (TLV) is quite different at its generation, development, and dissipation phases. Additionally, three typical unsteady structures, the oscillation of the primary TLV, the TLV breakdown, and the unsteadiness of the unsteady blockage cell, is identified by the DMD modes. Unsteady motions also largely affect the vortex structure and loss generation, especially after the vortex breakdown. The spatiotemporal structure identified by DMD provides a new understanding, which could be helpful for the modeling or flow control of the TLF.
Decarbonisation of high-temperature endothermic chemical reaction processes using a novel turbomachine: robustness of the concept to feed variability
Authors:   University of Oxford, Rubini Dylan , Karefyllidis Nikolas ,   University of Oxford, Xu Liping ,   University of Cambridge, Rosic Budimir ,   University of Oxford, Nauha Elina ,   Coolbrook Oy
Published: February 2024

This paper presents a revolutionary turbomachinery concept, referred to as the turbo-reactor, which has the potential to replace gas-fired radiant furnaces and decarbonise a wide range of hard-to-abate, high-temperature endothermic chemical reaction processes. While previous studies by the authors have confirmed the feasibility of using a turbo-reactor for steam cracking reactions, the numerical investigation presented in this work demonstrates its potential for eliminating emissions from a variety of energy-intensive chemical processes, including those used in the hydrogen industry. This step change in technology could be the catalyst needed to enable rapid scale-up of low-carbon hydrogen technology. The innovative design of the turbo-reactor is fundamentally based on converting all the mechanical energy imparted into internal energy, rather than pressure. This enables temperatures of up to 1700 ◦C (depending on fluid properties) to be achieved within an axial length in the order of one metre, resulting in a 100 – 1000Å~increase in power density compared to a surface heat exchanger. This paper presents the first comprehensive analysis of the turbo-reactor’s robustness and controllability across a broad spectrum of feeds, chemical reaction stages, Mach number regimes, and operating points, conclusively demonstrating the feasibility of a universal stage design strategy for various endothermic reaction processes.
A preliminary experimental study of the supercritical CO2 U-shaped compact heat exchanger for the hypersonic vehicle
Authors:   Research Insitute of Aero- Engine, Beihang University, Tang Zhongfu , Chen Yiming ,   Research Insitute of Aero- Engine, Beihang University, Liu Huoxing ,   Research Insitute of Aero- Engine, Beihang University
Published: February 2024

With the increase of the flight Mach number, hypersonic aircraft aerodynamic heat generation is more intense. In order to effectively improve the overall flight efficiency and heat utilization efficiency, it is necessary to use compact heat exchangers to take away these heat for redistribution, which promotes pre-cooling and heat management and other aspects of demand. However, there are still two key problems for those purposes: heat exchange medium and heat transfer and flow resistance characteristics. In view of the research of the above two problems, this paper adopts a U-shaped compact heat exchanger, using supercritical CO2 as the heat exchange medium. This paper achieved high temperature test conditions around 900±20K on the air side, and completes a series of heat exchange tests for the mass flow ratio of CO2/air of 1~1.5, and concludes that the maximum pressure loss on the outside of the heat exchanger does not exceed 9.5%, the maximum pressure loss on the CO2 side does not exceed 7.4%, and the flow resistance relationship is relatively complicated and discussed in paper. Finally, the source of the flow resistance were analyzed in detail, and quantitative results of the distribution and proportion of different types of losses were obtained. The maximum heat exchange efficiency calculated based on counterflow configuration is 0.63, and the maximum power of the test is 64KW.
Unsteady flow mechanism of a rotating instability in a 1.5-stage axial compressor
Authors:   Waseda University, Fujisawa Nobumichi , Yamagami Mai ,   IHI Corporation, Ohta Yutaka ,   Waseda University, Goto Takashi ,   IHI Corporation, Kato Dai ,   IHI Corporation
Published: February 2024

The unsteady flow mechanism of rotating instability (RI) in a 1.5-stage axial compressor is investigated through experimental and numerical analyses. The total pressure increase characteristics of the rotor blades show that a kink point occurred in a case involving a wide clearance, whereas the RI occurred below the kink point. The RI appears in the power spectrum as a gentle hump whose frequency is approximately 20%–40% of the blade-passing frequency at the blade tips. The mode of the RI disturbance increases as the flow rate decreases, whereas the propagation velocity remains unchanged. This causes the RI frequency to increase. The double-phase-locked averaging method is used to visualize the flow field inside the rotor blade when the RI occurred. The results show that as the flow rate decreases, the spacing of the pressure patterns inside the rotor blade decreases and the number of RI modes increases. Results of numerical analysis show that the RI is formed by the repeated collision and separation of the tip leakage vortex onto the pressure surface of the adjacent blade. The fluctuation in the inflow angle of the vortex entering the adjacent blade changes the blade-tip loading. The vortex fluctuations propagate in the circumferential direction.
Aeroelastic assessment of the second flexure mode excitation in a low pressure ratio fan
Authors:   IHI Corporation, Tateishi Atsushi , Tanaka Nozomi ,   IHI Corporation, Aotsuka Mizuho ,   IHI Corporation, Enoki Tomonori ,   IHI Corporation, Kusuda Shinya ,   IHI Corporation, Murooka Takeshi ,   IHI Corporation
Published: February 2024

During the development of high by-pass aircraft engine fans, stall flutter often becomes a major issue because it restricts their part-speed operability at near-stall conditions. Stall flutter is usually experienced on the first flexure mode, where a few nodal diameters are dominant. However, our recent tests showed strong non-synchronous excitation for the second flexure (2F) mode containing multiple nodal diameters, which is a distinguishing characteristic from well-known stall flutter. This paper aims to understand the mechanism of the observed 2F excitation. Aerodynamic damping is evaluated by nonlinear transient CFD simulations across a range of fan massflow near stall. The aerodynamic damping turns negative when vortex shedding near the blade tip spills upstream and interacts with the leading edge of the neighbouring blade. Also, the vortex shedding behaviour and resulting aerodynamic damping clearly depend on the blade amplitude. The vortex shedding has broadband spectra for both frequency and circumferential modes under low amplitude, and they lock on the blades’ motion under large amplitude. From these observations, it is concluded that the observed 2F excitation can be categorized into non-synchronous vibrations found in recent literature. The coincidence of blade vibration and vortex shedding is also discussed from unsteady signal processing.
Axial Compressor Design System with Direct Generation of 3D Geometry
Authors:   Faculty of Mech. Engineering University of Belgrade, Banjac Milan , Petkovic Djordje ,   Faculty of Mech. Engineering University of Belgrade, Madzar Teodora ,   Faculty of Mech. Engineering University of Belgrade, Petrovic Milan V. ,   Faculty of Mech. Engineering University of Belgrade
Published: February 2024

This paper presents a software system for the design of axial compressors assembled from several modular tools. The central feature is the possibility to generate a complete 2D and 3D design in a single run, using a basic set of general and stage-related parameters. This results in a geometry definition that can be analyzed with commercial CFD tools. The number of stages and the blade geometry are determined through the computing procedure, which preserves the input mean line parameters. Complementary programs can be used to evaluate the overall off-design performance and to examine and modify individual cascade sections before time-consuming CFD computations are engaged. Each tool is accompanied by a graphical interface for more accessible data analysis. The design examples and comparisons are demonstrated.
GRETA - An open-source generic research turbofan low-pressure compressor model
Authors:   Cranfield University, Zawadzki Natan , Szymański Artur ,   Cranfield University, Igie Uyioghosa ,   Cranfield University
Published: February 2024

A Generic Research Turbofan (GReTa) low-pressure compressor (LPC) model is introduced and made freely available to the community. The model comprises a fan stage and a four-stage booster with a pressure ratio of ∼1.6 each. GReTa was inspired by the Energy Efficient Engine (E3), and the design work was carried out using limited data in the public domain for the E3 and similar engines. First, a thermodynamic model of the engine was created to establish the design objectives. Subsequently, a detailed compressor design was developed and extensively characterised using Computational Fluid Dynamics (CFD) analysis. The fan stage performance surpassed the original design objectives, and the integrated low-pressure compressor demonstrated acceptable performance across the design envelope. It was concluded that the model sufficiently resembles the features of a modern civil turbofan and can be used as a benchmark geometry for cross-comparison of computational codes at the tested conditions. The availability of an open turbofan compressor validation benchmark in a highly restrictive sector is paramount to further advancing computational methods used for engine design verification and validation, leading to certification by analysis. This includes several aspects pertinent to engine safety, such as operation in adverse atmospheric conditions and close to operating limits, compressor fouling and erosion, as well as virtual prototyping of feasibility studies of novel cycles and engine architectures.
Meso-scale investigation on the deformation and failure behaviors of plain woven SiC/SiC with holes
Authors:   School of Power and Energy, NWPU, JING Xin , ZENG Fang ,   School of Power and Energy, NWPU
Published: February 2024

For plain woven SiC/SiC composites used in the aerospace thermal-structural applications, not only the pristine material properties but the open-hole performance are of critical concern for the components in service. In the present study, the influence of fiber preform and manufactured hole on the macro mechanical properties of plain woven SiC/SiC were investigated experimentally. Tensile tests at room temperature were conducted on SiC/SiC specimens with different hole apertures and configurations, and digital image correlation (DIC) method was used for full field strain measurement. The results showed that mesoscopic deformation and failure of pristine SiC/SiC specimens during tensile loading were closely related to the mesoscopic structure of plain woven fabrics. The notch sensitivity of SiC/SiC strength is weak, and the local mesoscopic deformation of the notch is affected by the work of macroscopic stress gradients and mesoscopic structures.
Unit commitment optimization of gas-fired generation at black point power station incorporating the efficiency, flexibility, reliability & cost
Authors:   CLP Power Hong Kong Limited, MAU Yuk-Hung , Ng Ki-On ,   CLP Power Hong Kong Limited, TSANG Prof. Danny H.K. ,   Hong Kong University of Science & Technology,   Hong Kong University of Science & Technology Clear Water Bay
Published: February 2024

Gas-fired generation has been considered one of the mainstream generation technologies nowadays and has become a vital part of the decarbonisation journey in Hong Kong. Having a significant impact on the business and environment, the utilisation of generation units has to be optimised so that additional gas generation can be accommodated and the performance of efficiency and reliability for the existing gas-fired generation units can be enhanced. Currently, at Black Point Power Station (BPPS) in Hong Kong, the generation scheduling is done manually based on the traditional approach. Each unit has its specific characteristic in terms of efficiency, cost, flexibility, reliability and performance according to its individual hardware condition, degradation and running regime. If those costs and various machine factors are not considered effectively, efficiently and intelligentially, the overall generation costs, as well as the carbon emission reduction, will not be optimised as a result. This study is to develop a Unit Commitment Optimisation (UCO) model with the help of state-of-the-art Artificial Intelligence and Machine Learning for optimising the daily scheduling of eight gas-fired generation units at BPPS. It illustrates the comparison and advantage of the newly developed optimisation model with the existing method. Moreover, a holistic review of the real-life generation cost, efficiency, maximum output power and condition-related data is completed to minimize modelling uncertainty. All the factors that affect the scheduling are further validated during the testing and tuning phase. The simulation result shows that the model is practical with sound good accuracy in efficiency, and cost optimisation for the BPPS machine scheduling.
Evaluation of fracture resistance of teeth with Class II Mesio-Occluso- Distal cavities restored by three different esthetic restorative materials: An In-vitro study
Authors: Guptha Anila Bandlapally Sreenivasa , Sri Raavi Bhavya , Garlapati Roopadevi , Vemuri Sayesh , Halder Niharika , Lahari Bolla
Published: February 2024

Aim - The aim of present investigation was to assess fracture resistance of teeth with Class II Mesio-Occluso-Distal (MOD) cavities filled with Microhybrid composite, Nanohybrid composite and Cention-N. Materials and Methods - 40 extracted maxillary premolars were kept in 0.1% thymol solution for 7 days, then subsequently in normal saline until use. All specimens were embedded 2mm below Cemento-enamel junction (CEJ) in self cure acrylic resin molds. They were then arbitrarily divided in 4 groups, each with 10 specimens (n=10). Group 1 consisted of intact teeth (Control group), whereas Group 2,3 and 4 contained prepared teeth with standardized class II MOD cavities filled with Microhybrid composite, Nanohybrid composite and Cention-N respectively. All the specimens were finished using composite finishing & polishing kit and were stored in 100% humidity at 37℃ for 24 hours. Each specimen was subjected to Fracture resistance (N) under Universal Testing Machine. Data collected was subjected to One-way analysis of variance and then subsequently to Tukey’s post-hoc test. Differences in groups were considered significant at p ≤ 0.05. Results - The results showed that Cention-N exhibited highest fracture resistance whereas Microhybrid composite had least fracture resistance when compared to other restorative groups. Conclusion - It can be inferred that Cention-N can be preferred for restoration of Class II MOD cavities in maxillary premolars over Nanohybrid composite or Microhybrid composite. Keywords - Cention-N, fracture resistance, Mesio-Occluso-Distal cavities, Microhybrid composite, Nanohybrid composite, Universal testing machine
Prioritizing factors for the adoption of IoT-based smart irrigation in Saudi Arabia: a GRA/AHP approach
Authors: Jabbari Abdoh , Teli Tawseef Ahmed , Masoodi Faheem , Reegu Faheem Ahmad , Uddin Mueen , Albakri Ashwag
Published: February 2024

The irrigation sector in the Kingdom of Saudi Arabia (KSA) confronts a range of obstacles, such as scarce water resources, the elevated salinity and alkalinity of irrigation water, inefficient irrigation practices, and inter-sectoral competition for water resources. These challenges have led to diminishing agricultural yields and abandonment of arable lands. Internet of Things (IoT)-based irrigation systems present a promising remedy for these issues. By curbing water wastage and ensuring precise water delivery to crops, IoT-based irrigation systems offer a viable solution to the challenges entrenched in traditional irrigation methodologies in KSA. However, the widespread implementation of an IoT-based Smart Irrigation System (I-SIMS) poses a multifaceted and intricate challenge in KSA. This study is focused on the identification of the factors and challenges through a systematic review and ranking of the challenges/factors that exert a significant influence on the adoption of I-SIMS. Ranking aids in determining the importance of various alternatives. It enables locating the best options that support the required objectives in complex decision situations. The study employs both Grey Relational Analysis (GRA) and Analytical Hierarchical Process (AHP) methodologies to prioritize these factors. The study’s conclusive findings indicate that among the challenges, technical expertise and security measures emerge as the foremost concerns that demand attention.
Mitochondrial DNA leakage triggers inflammation in age-related cardiovascular diseases
Authors: Ding Wanyue , Chen Jingyu , Zhao Lei , Wu Shuang , Chen Xiaomei , Chen Hong
Published: February 2024

Mitochondrial dysfunction is one of the hallmarks of cardiovascular aging. The leakage of mitochondrial DNA (mtDNA) is increased in senescent cells, which are resistant to programmed cell death such as apoptosis. Due to its similarity to prokaryotic DNA, mtDNA could be recognized by cellular DNA sensors and trigger innate immune responses, resulting in chronic inflammatory conditions during aging. The mechanisms include cGAS-STING signaling, TLR-9 and inflammasomes activation. Mitochondrial quality controls such as mitophagy could prevent mitochondria from triggering harmful inflammatory responses, but when this homeostasis is out of balance, mtDNA-induced inflammation could become pathogenic and contribute to age-related cardiovascular diseases. Here, we summarize recent studies on mechanisms by which mtDNA promotes inflammation and aging-related cardiovascular diseases, and discuss the potential value of mtDNA in early screening and as therapeutic targets.
Porous organic polymers-based fluorescent chemosensors for Fe(III) ions-a functional mimic of siderophores
Authors: Mohan Binduja , Shanmughan Ananthu , Krishna Alenthwar Vamshi , Noushija Mannanthara Kunhumon , Umadevi Deivasigamani , Shanmugaraju Sankarasekaran
Published: February 2024

Extended organic polymers such as amorphous Covalent Organic Polymers (COPs) and crystalline Covalent Organic Frameworks (COFs) are emerging functional polymeric materials that have recently been shown promises as luminescent materials for chemosensing applications. A wide variety of luminescence COPs and COFs have been synthesized and successfully used as fluorescence-sensing materials for hazardous environmental pollutants and toxic contaminants. This review exemplifies various COPs and COFs-based fluorescence sensors for selective sensing of Fe(III) ions. The fluorescence sensors are sorted according to their structural features and each section provides a detailed discussion on the synthesis and fluorescence sensing ability of different COPs and COFs towards Fe(III) ions. Also, this review highlights the limitations of the existing organic polymer-based chemosensors and future perspectives on translating COPs and COFs-based fluorescence sensors for the practical detection of Fe(III) ions.
Construction methods and biomedical applications of PVA-based hydrogels
Authors: Zhong Yi , Lin Qi , Yu Han , Shao Lei , Cui Xiang , Pang Qian , Zhu Yabin , Hou Ruixia
Published: February 2024

Polyvinyl alcohol (PVA) hydrogel is favored by researchers due to its good biocompatibility, high mechanical strength, low friction coefficient, and suitable water content. The widely distributed hydroxyl side chains on the PVA molecule allow the hydrogels to be branched with various functional groups. By improving the synthesis method and changing the hydrogel structure, PVA-based hydrogels can obtain excellent cytocompatibility, flexibility, electrical conductivity, viscoelasticity, and antimicrobial properties, representing a good candidate for articular cartilage restoration, electronic skin, wound dressing, and other fields. This review introduces various preparation methods of PVA-based hydrogels and their wide applications in the biomedical field.
Bibliometric analysis of intestinal microbiota and lung diseases
Authors: Sun Weiting , Zhou Tong , Ding Peng , Guo Liuxue , Zhou Xiujuan , Long Kunlan
Published: February 2024

Background

Increasing evidence suggests a close association between the intestinal microbiome and the respiratory system, drawing attention to studying the gut-lung axis. This research employs bibliometric methods to conduct a visual analysis of literature in the field of intestinal microbiota and lung diseases over the past two decades. It offers scientific foundations for research directions and critical issues in this field.

Methods

We retrieved all articles on intestinal microbiota and lung diseases from the SCI-Expanded of WoSCC on October 25, 2023. The analysis included original articles and reviews published in English from 2011 to 2023. We utilized Python, VOSviewer, and CiteSpace to analyze the retrieved data visually.

Results

A total of 794 publications were analyzed. China ranked first in the number of publications, while the United States had the highest citations and H-index. Jian Wang was the most prolific author. Zhejiang University was the institution with the highest number of publications. Frontiers in Microbiology was the journal with the most publications. Author keywords appearing more than 100 times included “intestinal microbiota/microbiome”, “microbiota/microbiome”, and “gut-lung axis”.

Conclusion

The correlation and underlying mechanisms between intestinal microbiota and lung diseases, including asthma, COPD, lung cancer, and respiratory infections, remain hot topics in research. However, understanding the mechanisms involving the gut-lung axis is still in its infancy and requires further elucidation.
Nuclear magnetic resonance study on wettability of shale oil reservoir
Authors: Yao Lanlan , Yang Zhengming , Li Haibo , Zhou Tiyao , Zhang Yapu , Wang Ning , Du Meng , Huang Qianhui , Chen Xinliang , Meng Huan
Published: February 2024

In order to identify and evaluate reservoir wettability, so as to select suitable mining methods to improve oil recovery, wettability evaluation through one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) technology combined with physical simulation experiments was carried out in this study, and the feasibility of the experimental method was verified by contact Angle method. According to the principle of hydrophilic inorganic content and hydrophobic organic content of shale, the wettability can be evaluated through vacuum self-imbibition oil and self-imbibition water physical simulation experiments combined with 1D NMR technology, that is, total water absorption can be considered as inorganic content, organic content can be obtained by subtracting total water absorption from total oil absorption, and adsorbed oil content can be obtained by subtracting pore volume from total oil absorption. In addition to the wettability measurement by contact Angle method to verify the experimental method, the occurrence ratio of adsorbed oil can also be verified twice by 2D NMR spectrum. The results show that the error between the proportion of adsorbed oil measured by 2D NMR spectrum and that measured by self-imbibition method is within 4%. In the saturated oil-bound water state, the bound water is within the relaxation interval of 1<T1<10 ms and 1<T2<10 ms, and the oil signal is within the relaxation interval of T1>10 ms and T2>10 ms. And the relaxation time of aqueous phase moved to the right compared with that in the saturated water state, the interaction force between water and the pore wall was weakened, showing the characteristics of free fluid, and the rock sample became oil-wet, which was consistent with the wettability results measured by contact Angle. Therefore, the wettability of rock samples can be evaluated by 1D NMR technique combined with vacuum imbibition method, or by analyzing the changes of NMR spectra of aqueous phase in completely saturated water and saturated oil-bound water.
Clarifying the contribution of multiscale pores to physical properties of Chang 7 tight sandstones: insight from full-scale pore structure and fractal characteristics
Authors: Li Zhen , Ren Yilin , Chang Rui , Zhang Yuanli , Zhang Xuze , Tian Weichao
Published: February 2024

The pore structure and its heterogeneity of tight reservoirs are key factors affecting the storage and percolation of crude oil. The pore system of Chang 7 tight sandstone has multi-scale and multi-type characteristics. However, the contribution of different pore types and pore sizes to the physical properties of Chang 7 tight sandstone is still unclear. In this paper, we collected a suite of Chang 7 tight sandstones to investigate the full-scale pore structure and fractal characteristics by casting thin section, field emission scanning electron microscope, two-dimensional multi-scale backscattered scanning electron microscopy, N2 adsorption (NA) and NMR. The pore diameters of Chang 7 tight sandstone are usually distributed between 0.001 and 20 μm. Intercrystalline pores are mainly distuibuted <500 nm. Dissolution pores vary from 100 nm to 100 μm. Residual intergranular pores range from 1 μm to 40 μm. Based on the fractal characteristics, pore system is divided into macropores (mainly >300 nm), mesopores (mainly 7–300 nm), and micropores (mainly <7 nm). Micropores are adsorb-fluid pores that do not contribute to the storage and percolation but contribute significantly to contrasting specific surface area. Mesopores represent bound-fluid pores and only contribute to total porosity but not to permeability. Macropores represent movable-fluid pores, contributing to both porosity and permeability. The content and heterogeneity of macropores control the quality of Chang 7 tight sandstone. When macropore volume is >12×10−3 mL/g, the continuous percolation network consists entirely of macropores, resulting in higher porosity and permeability of the reservoir. Moreover, reservoir physical properties show excellent correlation with macropore heterogeneity. These results demonstrate that the content and heterogeneity of macropores are key indicators indicating the quality of the Chang 7 tight sandstones.
Urinary miR-185-5p is a biomarker of renal tubulointerstitial fibrosis in IgA nephropathy
Authors: Duan Zhi-Yu , Bu Ru , Liang Shuang , Chen Xi-Zhao , Zhang Chun , Zhang Qiu-Yue , Li Ji-Jun , Chen Xiang-Mei , Cai Guang-Yan
Published: February 2024

Background

For IgA nephropathy (IgAN), tubular atrophy/interstitial fibrosis is the most important prognostic pathological indicator in the mesangial and endocapillary hypercellularity, segmental sclerosis, interstitial fibrosis/tubular atrophy, and presence of crescents (MEST-C) score. The identification of non-invasive biomarkers for tubular atrophy/interstitial fibrosis would aid clinical monitoring of IgAN progression and improve patient prognosis.

Methods

The study included 188 patients with primary IgAN in separate confirmation and validation cohorts. The associations of miR-92a-3p, miR-425-5p, and miR-185-5p with renal histopathological lesions and prognosis were explored using Spearman correlation analysis and Kaplan-Meier survival curves. Bioinformatics analysis and dual luciferase experiments were used to identify hub genes for miR-185-5p. The fibrotic phenotypes of tubular epithelial cells were evaluated in vivo and in HK-2 cells.

Results

miRNA sequencing and cohort validation revealed that the expression levels of miR-92a-3p, miR-425-5p, and miR-185-5p in urine were significantly increased among patients with IgAN; these levels could predict the extent of tubular atrophy/interstitial fibrosis in such patients. The combination of the three biomarkers resulted in an area under the receiver operating characteristic curve of 0.742. The renal prognosis was significantly worse in the miR-185-5p high expression group than in the low expression group (P=0.003). Renal tissue in situ hybridization, bioinformatics analysis, and dual luciferase experiments confirmed that miR-185-5p affects prognosis in patients with IgAN mainly by influencing expression of the target gene tight junction protein 1 (TJP1) in renal tubular epithelial cells. In vitro experiment revealed that an miR-185-5p mimic could reduce TJP1 expression in HK-2 cells, while increasing the levels of α-smooth muscle actin, fibronectin, collagen I, and collagen III; these changes promoted the transformation of renal tubular epithelial cells to a fibrotic phenotype. An miR-185-5p inhibitor can reverse the fibrotic phenotype in renal tubular epithelial cells. In a unilateral ureteral obstruction model, the inhibition of miR-185-5p expression alleviated tubular atrophy/interstitial fibrosis.

Conclusion

Urinary miR-185-5p, a non-invasive biomarker of tubular atrophy/interstitial fibrosis in IgAN, may promote the transformation of renal tubular epithelial cells to a fibrotic phenotype via TJP1.