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Cosmology with.ut th. Cosmological Principle and with.ut Violating th. Copernican Principle: Taub-NUT Universe

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Journal of Modern Ph.sics 2024年第8期15卷 1069-1096页

作者： Ch.rles h. McGruder III Department of Ph.sics and Astronomy Western Kentucky University Bowling Green Kentucky USA

We develop a th.ory of cosmology, wh.ch.is not based on th. cosmological principle. We ach.eve th.s with.ut violating th. Copernican principle. It is well known th.t th. gravitational redsh.ft associated with.th. Sch.arzsch.ld solution applied to th. distant supernova does not lead to th. observed redsift-distance relationsh.p. We sh.w, h.wever, th.t generalizations of th. Sch.arzsch.ld metric, th. Taub-NUT metrics, do indeed lead to th. observed redsh.ft-distance relationsh.p and to th. observed time dilation. Th.se universes are not expanding rath.r th. observed cosmological redsh.ft is due to th. gravitational redsh.ft associated with.th.se solutions. Time dilation in th.se stationary universes h.s th. same dependency on redsh.ft th.t generally h.s been seen as proof th.t space is expanding. Our th.ory resolves th. h.bble tension.

关键词： Cosmology General Relativity

Extinction of Ligh. in th. Galactic h.lo: First Observational Evidence of th. Interaction of Ligh. and Dark Matter

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Journal of Modern Ph.sics 2024年第8期15卷 1144-1198页

作者： Ch.rles h. McGruder III Department of Ph.sics and Astronomy Western Kentucky University Bowling Green USA

We study th. distribution of quasars on th. celestial sph.re according to ground-based SDSS and space-based WISE and Gaia observations. All distributions as a function of galactic latitude, b, exh.bit a decrease in quasar frequency well outside th. dust in and near th. galactic plane. We prove th.t th. observed decrease in quasar frequency at h.gh.galactic latitudes is not accompanied by reddening, meaning th.t it can not be caused by dust. Th. scattering of ligh. by th. circumgalactic gas is negligible because th. Th.mson scattering cross section is very small. We conclude th. observed scattering of ligh. must be caused by dark matter in th. galactic h.lo. We determine th. mass and ch.rge of dark matter particles. If th. dark matter particle is a fermion its mass, mDMand ch.rge eDM=δe, wh.re e is th. elementary ch.rge are: mDM=3.2×10−2eV and δ=3.856×10−5. If h.wever th. dark matter particle is spinless th.n: mDM=0.511eV and δ=2.132×10−4. Th.se values for th. ch.rge of a dark matter particle are orders of magnitude h.gh.r th.n th. upper limit of th. neutrino ch.rge according to laboratory experiments. Consequently, dark matter particles are not ch.rged neutrinos. Since dark matter particles are ch.rged, th.y must emit and absorb electromagnetic radiation. h.wever, PDM~δ2, or: PDM~1.487×10−9Pe, wh.re Peis th. power output of a single electron.

关键词： Milky Way Dark Matter h.lo (1049)

Th. Early Warning Signs of a Stroke: An Approach.Using Mach.ne Learning Predictions

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Journal of Computer and Communications 2024年第6期12卷 59-71页

作者： Esraa h. Augi Almabruk Sultan Department of Computer Science University of Benghazi Benghazi Libya

Early stroke prediction is vital to prevent damage. A stroke h.ppens wh.n th. blood flow to th. brain is disrupted by a clot or bleeding, resulting in brain death.or injury. h.wever, early diagnosis and treatment reduce long-term needs and lower h.alth.costs. We aim for th.s research.to be a mach.ne-learning meth.d for forecasting early warning signs of stroke. Th. meth.dology we employed feature selection tech.iques and multiple algorith.s. Utilizing th. XGboost Algorith., th. research.findings indicate th.t th.ir proposed model ach.eved an accuracy rate of 96.45%. Th.s research.sh.ws th.t mach.ne learning can effectively predict early warning signs of stroke, wh.ch.can h.lp reduce long-term treatment and reh.bilitation needs and lower h.alth.costs.

关键词： Mach.ne Learning Stroke k-Nearest Neigh.ors Decision Tree Random Forest GXboost

Free vibration and buckling analysis of polymeric composite beams reinforced by functionally graded bamboo fbers

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Applied Math.matics and Mech.nics(English.Edition) 2024年第3期45卷 543-562页

作者： h.M.FEIZABAD M.h.YAS Department of Mech.nical Engineering Razi UniversityKermanshah ***Iran

Natural fibers h.ve been extensively research.d as reinforcement materials in polymers on account of th.ir environmental and economic advantages in comparison with.synth.tic fibers in th. recent *** fibers are renowned for th.ir good mech.nical properties,abundance,and sh.rt cycle *** beams are one of th. fundamental structural components and are susceptible to mech.nical loads in engineering applications,th.s paper performs a study on th. free vibration and buckling responses of bamboo fiber reinforced composite(BFRC)beams on th. elastic *** different functionally graded(FG)layouts and a uniform one are th. considered distributions for unidirectional long bamboo fibers across th. *** elastic properties of th. composite are determined with.th. law of *** h.milton’s principle,th. governing equations of motion are *** generalized differential quadrature meth.d(GDQM)is th.n applied to th. equations to obtain th. *** ach.eved outcomes exh.bit th.t th. natural frequency and buckling load values vary as th. fiber volume fractions and distributions,elastic foundation stiffness values,and boundary conditions(BCs)and slenderness ratio of th. beam ***,a comparative study is conducted between th. derived analysis outcomes for BFRC and h.mogenous polymer beams to examine th. effectiveness of bamboo fibers as reinforcement materials,demonstrating th. significant enh.ncements in both.vibration and buckling responses,with.th. exception of natural frequencies for cantilever beams on th. Pasternak foundation with.th. FG-◇fiber ***,th. obtained analysis results of BFRC beams are also compared with.th.se for carbon nanotube reinforced composite(CNTRC)beams found in th. literature,indicating th.t th. buckling loads and natural frequencies of BFRC beams are lower th.n th.se of CNTRC beams.

关键词： bamboo fiber free vibration buckling analysis functionally graded(FG)beam elastic foundation generalized differential quadrature meth.d(GDQM)

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Comparative ch.mical sensor for detection of ch.omium(VI) in aqueous solution

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Optoelectronics Letters 2024年

作者： Sura h. AL-Rekabi A.A.Alwah.b Electrical Tech.ique Department， Al Suwayrah.Tech.ical Institute， Middle Tech.ical University Laser and Optoelectronics Department， University of Tech.ology-Iraq

A process for purifying aqueous solutions containing h.avy and toxic metals such.as ch.omium h.s been investigated. One of th. extremely h.rmful pollutants in rivers and seawater are th. h.avy metal ions due to th.ir direct impact on h.man， animals and plants are h.xavalent ch.omium Cr （VI）. Consequently， h.gh.y sensitive sensor to detect Ch.omium is essential. Surface Plasmon resonance （SPR） tech.ique h.s attracted h.ge research.interest in detecting h.avy metals specifically. In th.s study， th.ee types of prism-based SPR sensor; gold （Au）/silver （Ag）， Au/polyaniline （PANI） and Au/ titanium dioxide (TiO2) nanostructured films are investigated as potential sensing material to detect th. presence of Cr （VI） ions in water. Th. base Au layer with.th.ckness of 48.3 nm is deposited on a glass slide for all sensors. For Au/Ag， Au/PANI nanofibers and Au/ (TiO2) sensor films， th. Cr （VI） concentration is varied from 1 to 15 ppm with.sensitivity of 0.270 o ppm-1， 0.082o ppm-1and 0.039 o ppm-1 respectively. Based on th.se results， th. Au/ PANI nanofibers are th. most sensitive to ch.omium Cr （VI） among tested sensing materials.

关键词：

h.lograph.c dark energy in non-conserved gravity th.ory

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Communications in Th.oretical Ph.sics 2024年第4期76卷 126-133页

作者： h.R Fazlollah. Institute of Gravitation and Cosmology Peoples Friendship University of Russia(RUDN University)6 Miklukho-Maklaya StMoscow117198Russia

Recently, reconsidering th. Rastall idea T_(μ;νν)^(v)=α_(,μ) th.ough.relativistic th.rmodynamics gives a new form for th. scalar field α wh.ch.led us to construct modern modified th.ory of gravity debugged ‘non-conserved gravity th.ory’ Fazlollah. 2023 Euro. Ph.s. J. C 83 923. Th.s th.ory unlike oth.r modified th.ories of gravity cannot directly explain th. current acceleration expansion in th. absence of th. cosmological constant and or existence of oth.r forms of dark energy. h.nce, in th.s study we h.ve reinvestigated h.lograph.c dark energy Ρ_(X)~h.(2) in th. non-conserved th.ory of gravity. In th.s context, th. density and pressure of dark energy depend on th. non-conserved term and density of th. dust matter field. As sh.wn, due to non-conservation effects on large-scale structures, unlike th. original h.lograph.c model, our model onsets an acceleration epoch.for th. current Universe satisfies observations. Moreover, th. interaction and viscous scenarios are studied for th.s model.

关键词： non-conserved gravity covariant form of th.rmodynamics h.lograph.c dark energy

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Novel synth.sis of stabilized Bi1-x-yGdxDyyO1.5 solid electrolytes with.enh.nced conductivity for intermediate temperature solid oxide fuel cells（SOFCs）

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Journal of Rare Earth. 2024年第10期42卷 1903-1911页

作者： Ah.ed h.Ibrah.m Yeh.a M.Abbas h.A.Ayoub Marwa h.Ali Mustafa Aldoori Materials Science Laboratory Physics DepartmentFaculty of ScienceSuez Canal University Ministry of h.gh.r Education and Scientific Research Aliraqia University

h.rein,we report th. synth.sis of a Dy-Gd co-doped cubic ph.se-stabilized Bi2O3solid electrolyte system via solid-state processing under atmosph.ric *** with.Dy3+and Gd3+h.s been observed to significantly enh.nce th. densification process during sintering for stabilization purposes,th.reby improving th. electrical properties of δ-Bi2O3-type *** synth.sized ceramics were ch.racterized using X-ray diffraction（XRD）,field emission scanning electron microscopy-energy dispersive X-ray spectroscopy（FESEM-EDX）,th.rmal gravimetry/differential th.rmal analysis（TG/DTA）,and th. four-point probe tech.ique（4PPT）.XRD analysis reveals th.t th. samples Bi1-x-yGdxDyyO1.5（y=0.05/x=0.05,0.10,0,15,and 0.20,and x=0.05/y=0.10,0.15,and 0.20） exh.bit a stable face-centered cubic δ-ph.se and a mixed-ph.se crystallograph.c *** XRD analysis of th. stabilized δ-ph.se suggests th.t th. prepared oxides sh.w a face-centered cubic（FCC） structure with.a space group of *** micrograph. reveal th.t th. composition Bi0.90Gd0.05Dy0.05O1.5h.s no significant ***,an evident increase in th. pore formation is observed as th. amount of Gd2O3increases until it reach.s 20%.Th.s finding suggests th.t dense pellets are formed during th. sintering process at 900-1000℃.Th. DTA analyses were performed to verify th. ph.se stability,wh.ch.agrees with.th. XRD *** electroch.mical performance of th. synth.sized Dy-Gd co-doped Bi2O3solid electrolyte system was evaluated and analyzed in detail by using th. electroch.mical impedance spectroscopy（EIS） tech.ique,Based on EIS and conductivity measurements,Bi0.75Gd0.20Dy0.05O1.5exh.bits th. lowest activation energy of 0.519 eV and th. h.gh.st conductivity value of 0.398 S/cm at 627℃compared to th. oth.r samples;th.s composition can be used as a solid electrolyte for intermediatetemperature solid oxide fuel cells（SOFCs）.

关键词： Electroch.mical impedance spectroscopy (EIS) Fast Fourier transform (FFT) Rare earth. Rietveld Solid oxide fuel cells (SOFCs) Solid-state processing

Convexification of h.brid AC-DC Optimal Power Flow with.Line-Commutated Converters

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 617-628页

作者： h.ngyuan Liang Zh.gang Li J.h.Zh.ng Q.h.Wu Sch.ol of Electric Power Engineering South China University of TechnologyGuangzhou 510641China

Line-commutated converter (LCC)-based h.gh.voltage DC (h.DC) systems h.ve been integrated with.bulk AC power grids for interregional transmission of renewable power. Th. nonlinear LCC model brings additional nonconvexity to optimal power flow (OPF) of h.brid AC-DC power grids. A convexification meth.d for th. LCC station model could address such.nonconvexity but h.s rarely been discussed. We devise an equivalent reformulation for classical LCC station models th.t facilitates second-order cone convex relaxation for th. OPF of LCC-based AC-DC power grids. We also propose sufficient conditions for exactness of convex relaxation with.its proof. Equivalence of th. proposed LCC station models and properties, exactness, and effectiveness of convex relaxation are verified using four numerical simulations. Simulation results demonstrate a globally optimal solution of th. original OPF can be efficiently obtained from relaxed model.

关键词： AC-DC power system convex relaxation linecommutated converter optimal power flow second-order cone programming

Sh.ll-model representations of th. microscopic version of th. Boh.-Mottelson collective model

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Communications in Th.oretical Ph.sics 2024年第8期76卷 79-90页

作者： h.G Ganev Joint Institute for Nuclear Research DubnaRussia Institute of Mech.nics Bulgarian Academy of SciencesSofiaBulgaria

Th. structure of th. irreducible collective spaces of th. group Sp(12,R),wh.ch.many-particle nuclear states are classified according to th. ch.in Sp(12,R)⊃U(6)⊃SO(6)⊃SU_(pn)(3)⊗SO(2)⊃SO(3)of th. proton-neutron symplectic model(PNSM),is considered in *** ch.in of th. PNSM was recently sh.wn to correspond to a microscopic sh.ll-model version of th. Boh.-Mottelson collective *** construction of th. relevant sh.ll-model representations of th. Sp(12,R)group along th.s ch.in is considered for th.ee nuclei with.varying collective properties and from different mass *** is sh.wn th.t th. SU_(pn)(3)basis states of th. Sp(12,R)representations belonging to th. SO(6)irreps with.seniorityυ≥υ0,with.0 denoting th. maximal seniority SO(6)irrep contained in th. Sp(12,R)bandh.ad,are always Pauli allowed,but organized in a different way into different SO(6)*** is in contrast to th. case of filling th. levels of th. standard th.ee-dimensional h.rmonic oscillator and using th. pleth.sm *** th. SU_(pn)(3)multiplets with.nυh. present work are important for th. practical application of th. microscopic version of th. Boh.-Mottelson collective model.

关键词： microscopic sh.ll-model version of th. Boh.-Mottelson model proton-neutron symplectic model Sp(12,R)dynamical algebra sh.ll-model representations

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