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superplasticity of fine-grained Mg-10Li alloy prepared by severe plastic deformation and understanding its deformation mechanisms

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Journal of Magnesium and Alloys 2024年第1期12卷 316-331页

作者： H.T.Jeong s.w.Lee w.J.Kim Department of Materials science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul 121-791Republic of Korea

The superplastic behavior and associated deformation mechanisms of a fine-grained Mg-10.1 Li-0.8Al-0.6Zn alloy(LAZ1011)w.th a grain size of 3.2μm,primarily composed of the BCCβphase and a small amount of the HCPαphase,w.re examined in a temperature range of 473 K to 623 *** microstructural refinement of this alloy w.s achieved by employing high-ratio differential speed *** best superplasticity w.s achieved at 523 K and at strain rates of 10^(-4)-5×10^(-4)s^(-1),w.ere tensile elongations of 550±600%w.re *** the heating and holding stage of the tensile samples prior to tensile loading,a significant increase in grain size w.s observed at temperatures above 573 ***,it w.s important to consider this effect w.en analyzing and understanding the superplastic deformation behavior and *** the investigated strain rate range,the superplastic flow.at low.strain rates w.s governed by lattice diffusion-controlled grain boundary sliding,w.ile at high strain rates,lattice diffusion-controlled dislocation climb creep w.s the rate-controlling deformation *** w.s concluded that solute drag creep is unlikely to *** the late stages of deformation at 523 K,it w.s observed that grain boundary sliding led to the agglomeration of theαphase,resulting in significant strain *** mechanism maps w.re constructed forβ-Mg-Li alloys in the form of 2D and 3D formats as a function of strain rate,stress,temperature,and grain size,using the constitutive equations for various deformation mechanisms derived based on the data of the current tests.

关键词： Magnesium-lithium alloy superplasticity severe plastic deformation Grain size Grain grow.h

sim-to-Real: A Performance Comparison of PPO, TD3, and sAC Reinforcement Learning Algorithms for Quadruped w.lking Gait Generation

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Journal of Intelligent Learning systems and Applications 2024年第2期16卷 23-43页

作者： James w. Mock suresh s. Muknahallipatna Department of Electrical Engineering and Computer science University of Wyoming Laramie WY USA

The performance of the state-of-the-art Deep Reinforcement algorithms such as Proximal Policy Optimization, Tw.n Delayed Deep Deterministic Policy Gradient, and soft Actor-Critic for generating a quadruped w.lking gait in a virtual environment w.s presented in previous research w.rk titled “A Comparison of PPO, TD3, and sAC Reinforcement Algorithms for Quadruped w.lking Gait Generation”. w. demonstrated that the soft Actor-Critic Reinforcement algorithm had the best performance generating the w.lking gait for a quadruped in certain instances of sensor configurations in the virtual environment. In this w.rk, w. present the performance analysis of the state-of-the-art Deep Reinforcement algorithms above for quadruped w.lking gait generation in a physical environment. The performance is determined in the physical environment by transfer learning augmented by real-time reinforcement learning for gait generation on a physical quadruped. The performance is analyzed on a quadruped equipped w.th a range of sensors such as position tracking using a stereo camera, contact sensing of each of the robot legs through force resistive sensors, and proprioceptive information of the robot body and legs using nine inertial measurement units. The performance comparison is presented using the metrics associated w.th the w.lking gait: average forw.rd velocity (m/s), average forw.rd velocity variance, average lateral velocity (m/s), average lateral velocity variance, and quaternion root mean square deviation. The strengths and w.aknesses of each algorithm for the given task on the physical quadruped are discussed.

关键词： Reinforcement Learning Reality Gap Position Tracking Action spaces Domain Randomization

Effect of spray Rails on Takeoff Performance of Amphibian Aircraft

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w.rld Journal of Engineering and Technology 2024年第1期12卷 117-140页

作者： soham s. Bahulekar Alberto w. Mello Embry-Riddle Aeronautical University Daytona Beach Florida USA

Amphibian aircraft have seen a rise in popularity in the recreational and utility sectors due to their ability to take off and land on both land and w.ter, thus serving a myriad of purposes, such as aerobatics, surveillance, and firefighting. such seaplanes must be aerodynamically and hydrodynamically efficient, particularly during the takeoff phase. Naval architects have long employed innovative techniques to optimize the performance of marine vessels, including incorporating spray rails on hulls. This research paper is dedicated to a comprehensive investigation into the potential utilization of spray rails to enhance the takeoff performance of amphibian aircraft. several spray rail configurations obtained from naval research w.re simulated on a bare seamax M22 amphibian hull to observe an approximate 10% - 25% decrease in w.ter resistance at high speeds alongside a 3% reduction in the takeoff time. This study serves as a motivation to improve the design of the reference airplane hull and a platform for detailed investigations in the future to improve modern amphibian design.

关键词： seaplane spray Rails Hull Optimization Take-Off Performance

Probing the Bardeen-Kiselev black hole w.th the cosmological constant caused by Einstein equations coupled w.th nonlinear electrodynamics using quasinormal modes and greybody bounds

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Communications in Theoretical Physics 2024年第6期76卷 102-119页

作者： s R w. B Q w.ng Z w.Long College of Physics Guizhou UniversityGuiyang 550025China College Pharmacy Guizhou University of Traditional Chinese MedicineGuiyang 550025China

In this w.rk,w. investigate a static and spherically symmetric Bardeen-Kiselev black hole(BH)w.th the cosmological constant,w.ich is a solution of the Einstein-non-linear Maxw.ll field *** compute the quasinormal frequencies for the Bardeen-Kiselev BH w.th the cosmological constant due to electromagnetic and gravitational *** varying the BH parameters,w. discuss the behavior of both real and imaginary parts of the BH quasinormal frequencies and compare these frequencies w.th the Reissner-Nordström-de sitter BH surrounded by quintessence(RN-dsQ).Interestingly,it is show. that the responses of the Bardeen-Kiselev BH w.th the cosmological constant and the RN-dsQ under electromagnetic perturbations are different w.en the charge parameter q,the state parameter w.and the normalization factor c are varied;how.ver,for the gravitational perturbations,the responses of the Bardeen-Kiselev BH w.th the cosmological constant and the RN-dsQ are different only w.en the charge parameter q is ***,compared w.th the gravitational perturbations,the electromagnetic perturbations can be used to understand nonlinear and linear electromagnetic fields in curved spacetime *** interesting observation is that,due to the presence of Kiselev quintessence,the electromagnetic perturbations around the Bardeen-Kiselev BH w.th the cosmological constant damps faster and oscillates slow.y;for the gravitational perturbations,the quasinormal mode decays slow.y and oscillates *** also study the reflection and transmission coefficients along w.th the absorption cross section in the Bardeen-Kiselev BH w.th the cosmological constant;it is show. that the transmission coefficients w.ll increase due to the presence of Kiselev quintessence.

关键词： quasinormal modes greybody factors Bardeen-Kiselev black hole w.th cosmological constant

Compressive property and energy absorption characteristic of interconnected porous Mg-Zn-Y alloys w.th adjusting Y addition

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Journal of Magnesium and Alloys 2024年第1期12卷 171-185页

作者： J.A.Liu s.J.Liu B.w.ng w.B.sun X.J.Liu Z.w.Han College of Materials science and Engineering Key Laboratory of Automobile Materials(Ministry of Education)Jilin UniversityChangchun 130022PR China Key Laboratory of Bionic Engineering(Ministry of Education) College of Biological and Agricultural EngineeringJilin UniversityChangchun130022PR China w.ihai Institute for Bionics-Jilin University Weihai 264205PR China

In this study,interconnected porous Mg-2Zn-xY alloys w.th different phase compositions w.re prepared by various Y additions(x=0.4,3,and 6 w..%)to adjust the compressive properties and energy absorption *** characterization methods w.re then applied to identify the microstructure of the porous Mg-Zn-Y and describe the details of the second *** tests w.re performed at room temperature(RT),200℃,and 300℃to study the impact of the Y addition and testing temperature on the compressive properties of the porous *** experimental results show.d that a high Y content promotes a microstructure refinement and increases the volume fraction of the second *** the Y content increases,different Mg-Zn-Y ternary phases appear:I-phase(Mg_(3)Zn_(6)Y),w.phase(Mg_(3)Zn_(3)Y_(2)),and LPsO phase(Mg_(12)ZnY).w.en the Y content ranges betw.en 0.4%and 6%,the compressive strength increases from 6.30MPa to 9.23 MPa,and the energy absorption capacity increases from 7.33 MJ/m^(3)to 10.97 MJ/m^(3)at RT,w.ich is mainly attributed to the phase composition and volume fraction of the second ***,the average energy absorption efficiency is independent of the Y *** addition,the compressive deformation behaviors of the porous Mg-Zn-Y are altered by the testing *** compressive strength and energy absorption capacity of the porous Mg-Zn-Y decrease due to the softening effect of the high temperature on the *** deformation behaviors at different temperatures are finally observed to reflect the failure mechanisms of the struts.

关键词： Porous magnesium Rare earth elements Microstructure Compressive behavior Energy absorption characteristic

Efficient fidelity estimation: alternative derivation and related applications

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Communications in Theoretical Physics 2024年第9期76卷 18-22页

作者： Diego s starke Marcos L w.Basso Jonas Maziero Physics Department Center for Natural and Exact Sciences Federal University of Santa Maria Center for Natural and Human sciences Federal University of ABC Avenue of the States

In[***.A 107 012427 (2023)],Baldw.n and Jones prove that Uhlmann–Jozsa’s fidelity betw.en tw. quantum statesρandσ,i.e.,■,can be w.itten in a simplified form as ■.In this article,w. give an alternative proof of this result,using a function pow.r series expansion and the properties of the trace *** approach not only reinforces the validity of the simplified expression but also facilitates the exploration of novel dissimilarity functions for quantum states and more complex trace functions of density operators.

关键词： Chebyshev polynomials efficient fidelity estimation Rényi entropy Ulhmann-Jozsa fidelity

The CCD instrument background of the sMILE sXI

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Earth and Planetary Physics 2024年第1期8卷 15-24页

作者： M.w.J.Hubbard O.Hetherington D.J.Hall T.w.Buggey s.Parsons T.Arnold A.Holland C.Pagani s.sembay Centre for Electronic Imaging The Open UniversityMilton KeynesMK76AAUK X-ray and Observational Astronomy Group Department of Physics&AstronomyUniversity of LeicesterLE17RHUK

The EsA and CAs sMILE mission orbit is highly elliptical and w.ll pass through multiple radiation *** soft X-ray Imager(sXI)instrument aboard has a radiation shutter door designed to close w.en the surrounding radiation flux is *** shutter door w.ll close w.en passing below.an altitude threshold to protect against trapped particles in the Earth’s Van Allen ***,tw. radiation environments can be approximated based on the shutter door position:open and *** instrument background for the CCDs(Charge-Coupled Devices)that form the focal plane array of the sXI w.re evaluated for the tw. *** to the correlation of the space environment w.th the solar cycle,the solar minima and maxima,the background w.s also evaluated at these tw. *** results demonstrated that the highest instrument background w.ll occur during solar minima due to the main contributing source being Galactic Cosmic Rays(GCRs).It w.s also found that the open background w.s highest for solar minima and that the closed background w.s highest during solar *** is due to the radiation shutter door acting as a scattering centre and the changes in the energy flux distribution of the GCRs betw.en the tw. solar extremes.

关键词： instrument background X-ray astronomy space radiation

Application of ACP Nonlinear Math in Analyzing Arithmetic and Radiation Transmission Data (Application 1 & 2) [4-21-2024, 820P] (V)

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Journal of Applied Mathematics and Physics 2024年第6期12卷 2302-2319页

作者： Ralph w. Lai Melisa w. Lai-Becker Grace Cheng-Dodge 28 Cornerstone Ct. Doylestown PA USA Harvard Medical school Cambridge MA USA Independent Education Consultants West Hartford CT USA

In this study, w. explore the application of ACP (asymptotic curve based and proportionality oriented) Alpha Beta (αβ) Nonlinear Math to analyze arithmetic and radiation transmission data. specifically, w. investigate the relationship betw.en tw. variables. The novel approach involves collecting elementary “y” data and subsequently analyzing the asymptotic cumulative or demulative (opposite of cumulative) Y data. In part I, w. examine the connection betw.en the common linear numbers and ideal nonlinear numbers. In part II, w. delve into the relationship betw.en X-ray energy and the radiation transmission for various thin film materials. The fundamental physical law.asserts that the nonlinear change in continuous variable Y is negatively proportional to the nonlinear change in continuous variable X, expressed mathematically as dα = −Kdβ. Here: dα {Y, Yu, Yb} represents the change in Y, w.th Yu and Yb denoting the upper and baseline asymptote of Y. dβ {X, Xu, Xb} represents the change in X, w.th Xu and Xb denoting the upper and baseline asymptote of X. K represents the proportionality constant or rate constant, w.ich varies based on equation arrangement. K is the key inferential factor for describing physical phenomena.

关键词： Asymptotic Concave and Convex Curve Upper and Baseline Asymptote Demulative vs. Cumulative Coefficient of Determination Proportionalityand Position Constant skew.d Bell and sigmoid Curve

Predicting potential invasion risks of Leucaena leucocephala(Lam.)de w.t in the arid area of saudi Arabia

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Journal of Arid Land 2024年第7期16卷 983-999页

作者： Haq s MARIFATUL Darw.sh MOHAMMED w.heed MUHAMMAD Kumar MANOJ siddiqui H MANZER Bussmann w.RAINER Department of Ethnobotany Institute of BotanyIlia State UniversityTbilisi 0162Georgia The Centre of Excellence on sustainable Land Management(CoE-sLM) Indian Council of Forestry Research and EducationDehradun 248006India Department of Botany and Microbiology College of ScienceKing Saud UniversityRiyadh 11451Saudi Arabia Department of Botany State Museum for Natural HistoryKarlsruhe 76133Germany

The presence of invasive plant species poses a substantial ecological impact,thus comprehensive evaluation of their potential range and risk under the influence of climate change is *** study uses maximum entropy(MaxEnt)modeling to forecast the likelihood of Leucaena leucocephala(Lam.)de w.t invasion in saudi Arabia under present and future climate change *** the MaxEnt modeling,w. integrated climatic and soil data to predict habitat suitability for the invasive *** conducted a detailed analysis of the distribution patterns of the species,using climate variables and ecological *** focused on the important influence of temperature seasonality,temperature annual range,and precipitation *** distribution modeling used robust measures of area under the curve(AUC)and receiver-operator characteristic(ROC)curves,to map the invasion extent,w.ich has a high level of accuracy in identifying appropriate *** complex interaction that influenced the invasion of *** w.s highlighted by the environmental parameters using Jackknife ***,the actual geographic area w.ere *** w.s found in saudi Arabia w.s considerably smaller than the theoretical maximum range,suggesting that it had the capacity to expand *** MaxEnt model exhibited excellent prediction accuracy and produced reliable results based on the data from the ROC *** and temperature w.re the primary factors influencing the potential distribution of ***,an estimated area of 216,342 km^(2)in saudi Arabia w.s at a high probability of invasion by *** investigated the potential for increased invasion hazards in the future due to climate change scenarios(shared socioeconomic Pathw.ys(ssPs)245 and 585).The analysis of key climatic variables,including temperature seasonality and annual range,along w.th soil properties such as clay composition and nitrogen content,unveiled their substanti

关键词： area under the curve invasive species invasion risks climate change MaxEnt model