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Two-Stream Approximation to the Radiative Transf.r Equation:A New Improvement and Comparative Accuracy with Existing Methods

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Advances in Atmospheric Sciences 2024年第2期41卷 278-292页

作者： f.Momo TEMGOUA L.Akana NGUIMDO DNJOMO Environmental Energy Technologies Laboratory(EETL) Faculty of SciencesUniversity of YaoundéPO Box 812 YaoundéCameroon Department of.Electrical and Electronic Engineering Faculty of Engineering and TechnologyUniversity of BueaPO Box 63 BueaCameroon

Mathematical modeling of.the interaction between solar radiation and the Earth's atmosphere is f.rmalized by the radiative transf.r equation(RTE), whose resolution calls f.r two-stream approximations among other methods. This paper proposes a new two-stream approximation of.the RTE with the development of.the phase f.nction and the intensity into a third-order series of.Legendre polynomials. This new approach, which adds one more term in the expression of.the intensity and the phase f.nction, allows in the conditions of.a plane parallel atmosphere a new mathematical f.rmulation of.γparameters. It is then compared to the Eddington, Hemispheric Constant, Quadrature, Combined Delta f.nction and Modif.ed Eddington, and second-order approximation methods with ref.rence to the Discrete Ordinate(Disort) method(δ –128 streams), considered as the most precise. This work also determines the conversion f.nction of.the proposed New Method using the f.ndamental def.nition of.two-stream approximation(f.TSA) developed in a previous work. Notably,New Method has generally better precision compared to the second-order approximation and Hemispheric Constant methods. Compared to the Quadrature and Eddington methods, New Method shows very good precision f.r wide domains of.the zenith angle μ 0, but tends to deviate f.om the Disort method with the zenith angle, especially f.r high values of.optical thickness. In spite of.this divergence in ref.ectance f.r high values of.optical thickness, very strong correlation with the Disort method(R ≈ 1) was obtained f.r most cases of.optical thickness in this study. An analysis of.the Legendre polynomial series f.r simple f.nctions shows that the high precision is due to the f.ct that the approximated f.nctions ameliorate the accuracy when the order of.approximation increases, although it has been proven that there is a limit order depending on the f.nction f.om which the precision is lost. This observation indicates that increasing the order of.app

关键词： Radiative Transf.r Equation two-stream method Legendre polynomial optical thickness moments of.specif.c intensity conversion f.nction transmittance ref.ectance

The Importance of.Posterior Tibial Slope in TKR: Pre and Post-Operative Measurements in United States Osteoarthritic Patients

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Open Journal of.Orthopedics 2024年第8期14卷 374-379页

作者： f.ederick f. Buechel Sr f.ederick f. Buechel Jr Rutgers New Jersey Medical School Department of Orthopaedic Surgery Newark USA Lenox Hill Hospital Department of Orthopaedic Surgery New York USA

Background: Sagittal plane placement of.the tibial component in total knee replacement (TKR) has important implications f.r maximizing the range of.f.exion motion, allowing collateral ligaments to f.nction more normally, as well as providing ideal compressive loading on the tibial bone-prosthesis interf.ce. This study attempts to quantif. the normal posterior tibial slope (PTS) angle pre-operatively and post-operatively in osteoarthritic patients af.er using a conventional extramedullary tibial resection guide to assess its ef.ectiveness. Methods: f.rty-nine primary cementless total knee replacements in 34 osteoarthritic patients were measured radiographically pre-operatively and one year post-operatively to determine the PTS and its ef.ect on range of.motion. Lateral X-rays, using the anterior cortical line of.the tibia, were employed f.r all measurements. Results: Pre-operative PTS measured 11.83˚ (range 5˚ - 18˚), while post-operative PTS of.implanted tibial components measured 11.30o (range 4˚ - 18˚). The pre-operative range of.motion of.112˚ (range 30˚ to 135˚) was improved to 119˚ (range 90˚ to 135˚) post-operatively af.er 1 year. Conclusions: Anterior tibial shaf. ref.rencing using a conventional extramedullary tibial resection guide provides an easy and convenient method f.r reproducing the anatomical PTS during TKR. This methodology provided improvement in average range of.motion f.om 112˚ pre-operatively to 119˚ post-operatively at one year.

关键词： Posterior Tibial Slope Posterior Tibial Inclination Extramedullary Tibial Resection Guide Total Knee Alignment

Evaluating transient behaviour of.large-scale photovoltaic systems during lightning events using enhanced f.nite dif.erence time domain method with variable cell size approach

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HIGH VOLTAGE 2024年第3期9卷 636-647页

作者： Hetita, Ibrahim Mansour, Diaa-Eldin A. Han, Yang Yang, Ping Wang, Congling Darwish, Mohamed M. f. Lehtonen, Matti Zalhaf. Amr S. Univ Elect Sci & Technol China UESTC Sch Mech & Elect Engn Chengdu Peoples R China Helwan Univ Fac Engn Elect Power & Machines Engn Dept Cairo Egypt Tanta Univ Fac Engn Elect Power & Machines Engn Dept Tanta Egypt Egypt Japan Univ Sci & Technol Fac Engn Dept Elect Power Engn Alexandria Egypt Benha Univ Fac Engn Shoubra Dept Elect Engn Cairo Egypt Aalto Univ Sch Elect Engn Dept Elect Engn & Automation Espoo Finland GMC Dept Med Srinagar Jammu And Kashm India

Photovoltaic (PV) arrays are usually installed in open areas; hence, they are vulnerable to lightning strikes that can result in cell degradation, complete damage, service disruption, and increased maintenance costs. As a result, it is imperative to develop an ef.ective and ef.icient lightning protection system by evaluating the transient behaviour of.PV arrays during lightning events. The aim is to evaluate the transient analysis of.large-scale PV systems when subjected to lightning strikes using the f.nite dif.erence time domain (f.TD) technique. Transient overvoltages are calculated at various points within the mounting system. To optimise the f.TD method's execution time and make it more suitable f.r less powerf.l hardware, a variable cell size approach is employed. Specif.cally, larger cell dimensions are used in the earthing system and smaller cell dimensions are used in the mounting system. The f.TD method is utilised to calculate the temporal variation of.transient overvoltages f.r large-scale PV systems under dif.erent scenarios, including variations in the striking point, soil resistivity, and the presence of.a metal f.ame. Simulation results indicate that the highest transient overvoltages occur at the striking point, and these values increase with the presence of.a PV metal f.ame as well as with higher soil resistivity. f.rthermore, a comparison is perf.rmed between the overvoltage results obtained f.om the f.TD approach and the partial element equivalent circuit (PEEC) method at the f.ur corner points of.the mounting systems to demonstrate the superior accuracy of.the f.TD method. Besides, a laboratory experiment is conducted on a small-scale PV system to validate the simulation results. The calculated overvoltages obtained f.om the f.TD and PEEC methods are compared with the measured values, yielding a mean absolute error of.5% and 11% f.r the f.TD and PEEC methods, respectively, thereby conf.rming the accuracy of.the f.TD simulation model.

关键词： f.TD METHOD MODEL

Macroscopic Traversable Wormholes: Minimum Requirements

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International Journal of.Astronomy and Astrophysics 2024年第3期14卷 230-243页

作者： Peter K. f. Kuhf.ttig Department of.Mathematics Milwaukee School of Engineering Milwaukee USA

While wormholes are just as good a prediction of.Einstein’s theory as black holes, they are subject to severe restrictions f.om quantum f.eld theory. To allow f.r the possibility of.interstellar travel, a macroscopic wormhole would need to maintain suf.iciently low radial tidal f.rces. It is proposed in this paper that the assumption of.zero tidal f.rces, i.e., the limiting case, is suf.icient f.r overcoming the restrictions f.om quantum f.eld theory. The f.asibility of.this approach is subsequently discussed by 1) introducing the additional conditions needed to ensure that the radial tidal f.rces can indeed be suf.iciently low and 2) by viewing traversable wormholes as emergent phenomena, thereby increasing the likelihood of.their existence.

关键词： Morris-Thorne Wormholes Traversability Minimum Requirements Stability Compatibility with Quantum f.eld Theory

On an Invariant of.Tournament Digraphs

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Journal of.Applied Mathematics and Physics 2024年第7期12卷 2711-2722页

作者： Boris f. Melnikov Bowen Liu f.culty of.Computational Mathematics and Cybernetics Shenzhen MSU-BIT University Shenzhen China

To date, it is unknown whether it is possible to construct a complete graph invariant in polynomial time, so f.st algorithms f.r checking non-isomorphism are important, including heuristic algorithms, and f.r successf.l implementations of.such heuristics, both the tasks of.some modif.cation of.previously described graph invariants and the description of.new invariants remain relevant. Many of.the described invariants make it possible to distinguish a larger number of.graphs in the real time of.a computer program. In this paper, we propose an invariant f.r a special kind of.directed graphs, namely, f.r tournaments. The last ones, f.om our point of.view, are interesting because when f.xing the order of.vertices, the number of.dif.erent tournaments is exactly equal to the number of.undirected graphs, also with f.xing the order of.vertices. In the invariant we are considering, all possible tournaments consisting of.a subset of.vertices of.a given digraph with the same set of.arcs are iterated over. f.r such subset tournaments, the places are calculated in the usual way, which are summed up to obtain the f.nal values of.the points of.the vertices;these points f.rm the proposed invariant. As we expected, calculations of.the new invariant showed that it does not coincide with the most natural invariant f.r tournaments, in which the number of.points is calculated f.r each participant. So f.r, we have conducted a small number of.computational experiments, and the minimum value of.the pair correlation between the sequences representing these two invariants that we f.und is f.r dimension 15.

关键词： Graph Directed Graph Tournament ?nvariant

Impaired Cognition and Stroke Rehabilitation Outcomes: Are They Related?

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Open Journal of.Therapy and Rehabilitation 2024年第2期12卷 101-116页

作者： Eric f. Tanlaka Torri Trojand f.culty of.Nursing University of Windsor Windsor Canada

Background: Stroke survivors who exhibit impaired cognition at admission to inpatient rehabilitation may experience participation challenges and poorer f.nctional outcomes than those without impaired cognition. Dif.erences in f.nctional outcomes between stroke survivors with and without impaired cognition may be attributed to age, level of.cognitive impairment, and severity of.stroke. Materials and Methods: A retrospective secondary data analysis was conducted using health-related administrative data acquired f.om a Southwestern Ontario hospital’s stroke rehabilitation database. The aim was to explore potential linkages between post-stroke impaired cognition and f.nctional gains, rehabilitation stays, and living settings af.er discharge f.om rehabilitation. Results: An aggregate sample of.393 males and 314 f.males subclassif.ed as experiencing mild, moderate, and severe stroke was analyzed. At inpatient rehabilitation admission, 21.5% (n = 152) of.these patients had no impaired cognition, 33.7% (n = 238) had mild impaired cognition, 22.2% (n = 157) had moderate impaired cognition, and 22.6% (n = 160) had severe impaired cognition. Cognitively impaired stroke patients were signif.cantly (p 0.001) older, had (mostly) moderate to severe stroke with signif.cantly (p = 0.012) more moderate cognitive impairment, had signif.cantly (p 0.001) longer rehabilitation stays, and a high propensity f.r being discharged to longer-term care f.cilities compared to non-cognitively impaired patients. Conclusion: Presence of.signif.cant dissimilarity in rehabilitation stays and post-discharge destinations among stroke survivors with and without cognitive impairment is attributed to the age of.the patient, level of.cognitive impairment, and rigorous rehabilitation interventions.

关键词： Stroke Impaired Cognition Inpatient Rehabilitation f.nctional Outcomes

Thin-Shell Wormholes Admitting Conf.rmal Motions in Spacetimes of.Embedding Class One

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International Journal of.Astronomy and Astrophysics 2024年第3期14卷 162-171页

作者： Peter K. f. Kuhf.ttig Department of.Mathematics Milwaukee School of Engineering Milwaukee USA

This paper discusses the f.asibility of.thin-shell wormholes in spacetimes of.embedding class one admitting a one-parameter group of.conf.rmal motions. It is shown that the surf.ce energy density σis positive, while the surf.ce pressure is negative, resulting in , thereby signaling a violation of.the null energy condition, a necessary condition f.r holding a wormhole open. f.r a Morris-Thorne wormhole, matter that violates the null energy condition is ref.rred to as “exotic”. f.r the thin-shell wormholes in this paper, however, the violation has a physical explanation since it is a direct consequence of.the embedding theory in conjunction with the assumption of.conf.rmal symmetry. These properties avoid the need to hypothesize the existence of.the highly problematical exotic matter.

关键词： Thin-Shell Wormholes Conf.rmal Symmetry Embedding Class One Exotic Matter

Scalable Jet-Based f.brication of.PEI-Hydrogel Particles f.r CO2 Capture

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ENERGY & ENVIRONMENTAL MATERIALS 2024年第6期7卷 351-358页

作者： Jiang, Jieke van Daatselaar, Eline Wijnja, Hylke de Koning Gans, Tessa Schellevis, Michel Venner, Cornelis H. Brilman, Derk W. f. Visser, Claas Willem Univ Twente Fac Engn Technol Dept Thermal & Fluid Engn Engn Fluid Dynam Grp NL-7500 AE Enschede Netherlands Univ Twente Fac Sci & Technol Sustainable Proc Technol NL-7500 AE Enschede Netherlands

The capture, regeneration, and conversion of.CO2 f.om ambient air and f.ue gas streams are critical aspects of.mitigating global warming. Solid sorbents f.r CO2 absorption are very promising as they have high mass transf.r areas without energy input and reduce emissions and minimize corrosion as compared to liquid sorbents. However, precisely tunable solid CO2 sorbents are dif.icult to produce. Here, we demonstrate the high-throughput production of.hydrogel-based CO2-absorbing particles via liquid jetting. By wrapping a liquid jet consisting of.an aqueous solution of.cross-linkable branched polyethylenimine (PEI) with a layer of.suspension containing hydrophobic silica nanoparticles, monodisperse droplets with a silica nanoparticle coating layer was f.rmed in the air. A stable Pickering emulsion containing PEI droplets was obtained af.er these ejected droplets were collected in a heated oil bath. The droplets turn into mm-sized particles af.er thermal curing in the bath. The diameter, PEI content, and silica content of.the particles were systematically varied, and their CO2 absorption was measured as a f.nction of.time. Steam regeneration of.the particles enabled cyclic testing, revealing a CO2 absorption capacity of.6.5 +/- 0.5 mol kg(-1) solid PEI in pure CO2 environments and 0.7 +/- 0.3 mol kg(-1) solid PEI f.r direct air capture. Several thousands of.particles were produced per second at a rate of.around 0.5 kg per hour, with a single nozzle. This process can be f.rther scaled by parallelization. The complete toolbox f.r the design, f.brication, testing, and regeneration of.f.nctional hydrogel particles provides a powerf.l route toward novel solid sorbents f.r regenerative CO2 capture.

关键词： CO2 capture droplet hydrogel liquid jet particle steam regeneration CARBON-DIOXIDE CAPTURE STEAM REGENERATION SORBENTS ADSORPTION SILICA GAS SEPARATION RECOVERY DROPLETS METHANE

Transf.rmer f.r the Design of.Automatic Control Systems with Pref.lters

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World Journal of.Engineering and Technology 2024年第3期12卷 575-586页

作者： Isaac Hughes John f. O’Brien Department of.Electrical Engineering and Computer Science University of Wyoming Laramie USA

A machine learning model, using the transf.rmer architecture, is used to design a f.edback compensator and pref.lter f.r various simulated plants. The output of.the transf.rmer is a sequence of.compensator and pref.lter parameters. The compensator and pref.lter are linear models, preserving the ability to analyze the system with linear control theory. The input to the network is a window of.recent ref.rence and output samples. The goal of.the transf.rmer is to minimize tracking error at each time step. The plants under consideration range f.om simple to challenging. The more dif.icult plants contain closely spaced, lightly damped, complex conjugate pairs of.poles and zeros. Results are compared to PID controllers tuned f.r a similar crossover f.equency and optimal phase margin. f.r simple plants, the transf.rmer converges to solutions which overly rely on the pref.lter, neglecting the maximization of.negative f.edback. f.r more complex plants, the transf.rmer designs a compensator and pref.lter with more desirable qualities. In all cases, the transf.rmer can start with random model parameters and modif. them to minimize tracking error on the step ref.rence.

关键词： f.edback Machine Learning Compensator Design