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Heat Transfer Enhancement of the Absorber Tube in a Parabolic Trough Solar Collector through the Insertion of Novel Cylindrical Turbulators

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Fluid Dynamics & Materials Processing 2024年第6期20卷 1279-1297页

作者： Yasser Jebbar Fadhil Fluiful Wisam Khudhayer department of Electrical Techniques Al-Mussaib Technical InstituteAl-Furat Al-Awsat Technical UniversityBabilIraq department of Physics Collage of ScienceUniversity of KerbalaKarbalaIraq department of Energy Engineering Collage of Engineering/Al-MusayabUniversity of BabylonBabilIraq

This study includes an experimental and numerical analysis of the performances of a parabolic trough collector(PTC)with and without cylindrical *** PTC is designed with dimensions of 2.00 m in length and 1.00 m in *** related reflector is made of lined sheets of aluminum,and the tubes are made of stainless steel used for the absorption of *** have an outer diameter of 0.051 m and a wall thickness of 0.002 ***,used as a heat transfer fluid(HTF),flows through the absorber tube at a mass flow rate of 0.7 kg/*** dimensions of cylindrical turbulators are 0.04 m in length and 0.047 m in *** are performed using the ANSYS Fluent 2020 R2 *** PTC performance is evaluated by comparing the experimental and numerical outcomes,namely,the outlet temperature,useful heat,and thermal efficiency for a modified tube(MT)(tube with novel cylindrical turbulators)and a plain tube(PT)(tube without novel cylindrical turbulators).According to the results,the experimental outlet temperatures recorded 63.2°C and 50.5°C for the MT and PT,*** heat gain reaches 1137.5 Win the MT and 685.8 Win the *** to the PT collector,the PTC exhibited a(1.64 times)higher efficiency.

关键词： Parabolic trough collector turbulators absorber tube ANSYS thermal efficiency

Research advances in enhanced coal seam gas extraction by controllable shock wave fracturing

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International Journal of Coal Science & Technology 2024年第3期11卷 1-31页

作者： Chaojun Fan Hao Sun Sheng Li Lei Yang Bin Xiao Zhenhua Yang Mingkun Luo Xiaofeng Jiang Lijun Zhou College of Mining Liaoning Technical UniversityFuxin123000China College of Safety Science and Engineering Liaoning Technical UniversityFuxin123000China Energy Business department Shanxi Lu’an Chemical GroupChangzhi046200China

With the continuous increase of mining in depth,the gas extraction faces the challenges of low permeability,great ground stress,high temperature and large gas pressure in coal *** controllable shock wave(CSW),as a new method for enhancing permeability of coal seam to improve gas extraction,features in the advantages of high efficiency,eco-friendly,and low *** order to better utilize the CSW into gas extraction in coal mine,the mechanism and feasibility of CSW enhanced extraction need to be *** this paper,the basic principles,the experimental tests,the mathematical models,and the on-site tests of CSW fracturing coal seams are reviewed,thereby its future research directions are *** on the different media between electrodes,the CSW can be divided into three categories:hydraulic effect,wire explosion and excitation of energetic materials by detonating *** the process of propagation and attenuation of the high-energy shock wave in coal,the shock wave and bubble pulsation work together to produce an enhanced permeability effect on the coal *** stronger the strength of the CSW is,the more cracks created in the coal is,and the greater the length,width and area of the cracks *** repeated shock on the coal seam is conducive to the formation of complex network fracture system as well as the reduction of coal seam strength,but excessive shock frequency will also damage the coal structure,resulting in the limited effect of the enhanced gas *** the influence of ground stress,the crack propagation in coal seam will be *** difference of horizontal principal stress has a significant impact on the shape,propagation direction and connectivity of the CSW induced *** permeability enhancement effect of CSW is affected by the breakage degree of coal *** shock wave is absorbed by the broken coal,which may hinder the propagation of CSW,resulting in a poor effect of permeability *** arranging two a

关键词： Controllable shock wave Permeability enhancement Gas extraction Basic principle Experimental test Mathematical models On-site test

Prospects and challenges in electrochemical nitrogen activation for ammonia synthesis

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Science China Chemistry 2024年

作者： Xianbiao Fu Ib Chorkendorff department of Physics Technical University of Denmark

“The fixation of atmospheric nitrogen stands as one of the profound discoveries awaiting the ingenuity of chemists,”proclaimed William Crookes in his 1898 speech [1]. This statement swiftly surged like a colossal wave, making a significant impact on both academia and industry for N2activation. Nitrogen fixation to make ammonia （NH3） has profound impacts on fertilizer, pharmaceuticals, chemical production, and energy storage [2,3].

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Cybernet Model:A New Deep Learning Model for Cyber DDoS Attacks Detection and Recognition

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Computers, Materials & Continua 2024年第1期78卷 1275-1295页

作者： Azar Abid Salih Maiwan Bahjat Abdulrazaq department of Information Technology Technical College of DuhokDuhok Polytechnic UniversityDuhokIraq department of Computer Science Faculty of ScienceUniversity of ZakhoDuhokIraq

Cyberspace is extremely dynamic,with new attacks arising *** cybersecurity controls is vital for network *** Learning(DL)models find widespread use across various fields,with cybersecurity being one of the most crucial due to their rapid cyberattack detection capabilities on networks and *** capabilities of DL in feature learning and analyzing extensive data volumes lead to the recognition of network traffic *** study presents novel lightweight DL models,known as Cybernet models,for the detection and recognition of various cyber Distributed Denial of Service(DDoS)*** models were constructed to have a reasonable number of learnable parameters,i.e.,less than 225,000,hence the name“lightweight.”This not only helps reduce the number of computations required but also results in faster training and inference ***,these models were designed to extract features in parallel from 1D Convolutional Neural Networks(CNN)and Long Short-Term Memory(LSTM),which makes them unique compared to earlier existing architectures and results in better performance *** validate their robustness and effectiveness,they were tested on the CIC-DDoS2019 dataset,which is an imbalanced and large dataset that contains different types of DDoS *** results revealed that bothmodels yielded promising results,with 99.99% for the detectionmodel and 99.76% for the recognition model in terms of accuracy,precision,recall,and F1 ***,they outperformed the existing state-of-the-art models proposed for the same ***,the proposed models can be used in cyber security research domains to successfully identify different types of attacks with a high detection and recognition rate.

关键词： Deep learning CNN LSTM Cybernet model DDoS recognition

Study of relationship between motion of mechanisms in gas operated weapon and its shock absorber

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Defence Technology（防务技术） 2024年第3期33卷 42-54页

作者： Jiri Balla Roman Vitek Dung Nguyen Van Zbynek Krist Hung Nguyen Van department of Weapons and Ammunition University of Defence BrnoCzech Republic department of Weapons Le Quy Don Technical UniversityHanoiViet Nam department of Design and Special Engineering Alexander Dubcek University of TrencinSlovakia

The article deals with the motion of the breech block carrier and the weapon casing of an automatic weapon mounted on a flexible carriage and the base of the *** works,which did not consider the dynamic properties of the base of the weapon,did not allow to reconcile the calculated and experimental results of the weapon casing displacement when shooting from firing *** the analysis of the motion of individual parts,the methods of mathematical modelling and firing experiments using a high-speed camera were *** show the best accord with experiment when modelling the system with 4 degrees of *** oscillation of the system regarding the movement of the breech block carrier and the weapon casing was investigated under changed conditions of rate of fire,the use of a muzzle brake and different types of shock *** velocities and displacements of the weapon casing and the breech block carrier at different values of the impulse of the gases to the breech block carrier were determined.

关键词： Shock absorber Gas-operated weapon Force-impulse diagram Recoil system Breech block carrier

Risk-averse Robust Interval Economic Dispatch for Power Systems with Large-scale Wind Power Integration

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 105-116页

作者： Zhenjia Lin Haoyong Chen Jinbin Chen Jianping Huang Mengshi Li School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China department of Electrical Engineering Technical University of DenmarkDenmark

This paper presents a robust interval economic dispatch(RIED)model for power systems with large-scale wind power *** from existing interval optimization(IO)approaches that merely rely on the upper and lower boundaries of random variables,the distribution information retained in the historical data is introduced to the IO method in this *** on the available probability distribution function(PDF),wind power curtailment and load shedding are quantified as the operational risk and incorporated into the decision-making *** this model,we need not rely on the forecasted value of wind power,which is randomly fluctuating and quite ***,when the PDFs of wind power are taken into account,the resulting dispatch solution makes a good tradeoff between the generation cost and the operational ***,the RIED model yields an optimal dispatch solution for thermal units and the allowable intervals of wind power for the wind farms,which efficiently mitigates the uncertainty in wind power generation and provides more practical suggestions for system *** studies are conducted on a modified IEEE-118 bus system and the results verify the effectiveness of the proposed RIED model.

关键词： Economic dispatch interval optimization risk-averse wind power generation

Correlation of work function and stacking fault energy through Kelvin probe force microscopy and nanohardness in diluteα-magnesium

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Journal of Magnesium and Alloys 2024年第1期12卷 237-250页

作者： Yigit Türe Ali Arslan Kaya Hüseyin Aydin Jiang Peng Servet Turan Eskisehir technical University Porsuk Vocational SchoolElectronics and Automation DepartmentProgram of MechatronicsEskisehirTurkey Mugla Sitki Kocman University Engineering FacultyMetallurgy and Materials Engineering DepartmentMuglaTurkey Hüseying Aydın TUBITAK MRCTurkey Jiang Peng Chongqing UniversityChina Eskisehir technical University Engineering FacultyMaterials Science and Engineering DepartmentEskisehirTurkey

Electronic interactions of the Group 2A elements with magnesium have been studied through the dilute solid solutions in binary Mg-Ca,Mg-Sr and Mg-Ba *** investigation incorporated the difference in the‘Work Function'(ΔWF)measured via Kelvin Probe Force Microscopy(KPFM),as a property directly affected by interatomic bond types,*** electronic structure,nanoindentation measurements,and Stacking Fault Energy values reported in the *** was shown that the nano-hardness of the solid-solutionα-Mg phase changed in the order of Mg-Ca>Mg-Sr>***,it was shown,by also considering the nano-hardness levels,that SFE of a solid-solution is closely correlated with its‘Work Function'***-hardness measurements on the eutectics andΔWF difference between eutectic phases enabled an assessment of the relative bond strength and the pertinent electronic structures of the eutectics in the three *** withΔWF and at least qualitative verification of those computed SFE values with some experimental measurement techniques were considered important as those computational methods are based on zero Kelvin degree,relatively simple atomic models and a number of *** asserted by this investigation,if the results of measurement techniques can be qualitatively correlated with those of the computational methods,it can be possible to evaluate the electronic structures in alloys,starting from binary systems,going to ternary and then multi-elemental *** investigation has shown that such a qualitative correlation is *** all,the SFE values are not treated as absolute values but rather become essential in comparative investigations when assessing the influences of alloying elements at a fundamental level,that is,free electron density *** study indicated that the principles of‘electronic metallurgy'in developing multi-elemental alloy systems can be followed via practical experimental methods,i.e.ΔWF measurements using KPF

关键词： Mg alloys Dilute alloys Work function Stacking fault energy Kelvin probe force microscopy Short range order Miedema Nanoindentation Eutectics

Epidermolysis Bullosa Pruriginosa in Two Siblings:A Case Report

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International Journal of Dermatology and Venereology 2024年第1期7卷 52-54页

作者： Jongjin Suwanthaweemeesuk Chatip Phunmanee Sasathorn Singthong Oraya Kwangsukstid Chavalit Supsrisunjai Institute of Dermatology Department of Medical ServicesMinistry of Public HealthBangkok 10400Thailand

Introduction:Epidermolysis bullosa pruriginosa(EBP)is a rare clinical subtype of inherited dystrophic epidermolysis bullosa(DEB)caused by type VII collagen *** onset of EBP is variable and may present in late *** clinical features of EBP include prurigo-like papules,plaques,nodules,or linear configuration on the lower ***,we reported two sisters with *** presentation:We identified two Thai sisters with mild to moderate form of EBP,which resulted from a shared glycine substitution(Gly2287Val)in COL7A1 identified by genomic ***:The histology and molecular findings of both cases supported a diagnosis of dystrophic EBP,however,the clinical manifestations differ between both ***:Molecular testing is the key for the diagnosis of EBP due to nonspecific clinical manifestation and histologic findings,however,there is no clear genotype-phenotype correlation in EBP.

关键词： COL7A1 dystrophic epidermolysis bullosa epidermolysis bullosa pruriginosa Gly2287Val

Bridging element-free Galerkin and pluri-Gaussian simulation for geological uncertainty estimation in an ensemble smoother data assimilation framework

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Petroleum Science 2024年第3期21卷 1683-1698页

作者： Bogdan Sebacher Remus Hanea department of Applied Informatics Military Technical Academy“Ferdinand I”Bucharest 050141Romania Equinor Sandslivegen 905254 SandsliBergenNorway

The facies distribution of a reservoir is one of the biggest concerns for geologists,geophysicists,reservoir modelers,and reservoir engineers due to its high importance in the setting of any reliable decisionmaking/optimization of field development *** approach for parameterizing the facies distribution as a random variable comes naturally through using the probability *** the prior probability fields of facies come either from a seismic inversion or from other sources of geologic information,they are not conditioned to the data observed from the cores extracted from the *** paper presents a regularized element-free Galerkin(R-EFG)method for conditioning facies probability fields to facies *** conditioned probability fields respect all the conditions of the probability theory(*** the values are between 0 and 1,and the sum of all fields is a uniform field of 1).This property achieves by an optimization procedure under equality and inequality constraints with the gradient projection *** conditioned probability fields are further used as the input in the adaptive pluri-Gaussian simulation(APS)methodology and coupled with the ensemble smoother with multiple data assimilation(ES-MDA)for estimation and uncertainty quantification of the facies *** history-matching of the facies models shows a good estimation and uncertainty quantification of facies distribution,a good data match and prediction capabilities.

关键词： Element free Galerkin(EFG) Adaptive pluri-Gaussian simulation(APS) Facies distribution estimation Ensemble smoother with multipledata assimilation(ESMDA)