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Kinematic analysis of flexible bipedal robotic systems

Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 795-818页

作者： r.FAZEL A.M.SHAFEI S.r.NEKOO Department of Mechanical Engineering Shahid Bahonar University of KermanKerman ***Iran Departamento de Ingenieria de Sistemas y Automatica Escuela Técnica Superior de IngenieriaUniversidad de SevillaSeville 41092Spain

In spite of its intrinsic complexities,the passive gait of bipedal robots on a sloping ramp is a subject of interest for numerous *** distinguishes the present research from similar works is the consideration of flexibility in the constituent links of this type of robotic *** is not a far-fetched assumption because in the transient(impact)phase,due to the impulsive forces which are applied to the system,the likelihood of exciting the vibration modes increases ***,the human leg bones that are involved in walking are supported by viscoelastic muscles and ***,for achieving more exact results,it is essential to model the robot links with viscoelastic *** this end,the Gibbs-Appell formulation and Newton's kinematic impact law are used to derive the most general form of the system's dynamic equations in the swing and transient phases of *** most important issue in the passive walking motion of bipedal robots is the determination of the initial robot configuration with which the system could accomplish a periodic and stable gait solely under the effect of gravitational *** extremely unstable nature of the system studied in this paper and the vibrations caused by the impulsive forces induced by the impact of robot feet with the inclined surface are some of the very serious challenges encountered for achieving the above-mentioned *** overcome such challenges,an innovative method that uses a combination of the linearized equations of motion in the swing phase and the algebraic motion equations in the transition phase is presented in this paper to obtain an eigenvalue *** solving this problem,the suitable initial conditions that are necessary for the passive gait of this bipedal robot on a sloping surface are *** effects of the characteristic parameters of elastic links including the modulus of elasticity and the Kelvin-Voigt coefficient on the walking stability of this type of

关键词： bipedal robot flexible link swing phase transient phase eigenvalue problem Kelvin-Voigt coefficient

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The effects of data aggregation on long-term projections of forest stands development

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Forest Ecosystems 2024年第3期11卷 381-389页

作者： Kobra Maleki rasmus Astrup Nicolas Cattaneo Wilson Lara Henao Clara anton-Fernandez Norwegian Institute of Bioeconomy research Division of Forestry and Forest ResourcesP.O.Box 115ÅsNO-1431Norway

Forest management planning often relies on Airborne Laser Scanning(ALS)-based Forest Management Inventories(FMIs)for sustainable and efficient *** the area-based(ABA)approach,these inventories estimate forest characteristics for grid cell areas(pixels),which are then usually summarized at the stand *** the ALS-based high-resolution Norwegian Forest resource Maps(16 m×16 m pixel resolution)alongside with stand-level growth and yield models,this study explores the impact of three levels of pixel aggregation(standlevel,stand-level with species strata,and pixel-level)on projected stand *** results indicate significant differences in the projected outputs based on the aggregation ***,the most substantial difference in estimated volume occurred between stand-level and pixel-level aggregation,ranging from-301 to+253 m^(3)·ha^(-1)for single *** differences were,on average,higher for broadleaves than for spruce and pine dominated stands,and for mixed stands and stands with higher variability than for pure and homogenous *** conclusion,this research underscores the critical role of input data resolution in forest planning and management,emphasizing the need for improved data collection practices to ensure sustainable forest management.

关键词： Growth and yield models Dominant species Norway spruce Scots pine Broadleaves Forest resource map Stand variability

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Holographic dark energy in non-conserved gravity theory

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Communications in Theoretical Physics 2024年第4期76卷 126-133页

作者： H r Fazlollahi Institute of Gravitation and Cosmology Peoples Friendship University of Russia(RUDN University)6 Miklukho-Maklaya StMoscow117198Russia

recently, reconsidering the rastall idea T_(μ;νν)^(v)=α_(,μ) through relativistic thermodynamics gives a new form for the scalar field α which led us to construct modern modified theory of gravity debugged ‘non-conserved gravity theory’ Fazlollahi 2023 Euro. Phys. J. C 83 923. This theory unlike other modified theories of gravity cannot directly explain the current acceleration expansion in the absence of the cosmological constant and or existence of other forms of dark energy. Hence, in this study we have reinvestigated holographic dark energy Ρ_(X)~H^(2) in the non-conserved theory of gravity. In this context, the density and pressure of dark energy depend on the non-conserved term and density of the dust matter field. As shown, due to non-conservation effects on large-scale structures, unlike the original holographic model, our model onsets an acceleration epoch for the current Universe satisfies observations. Moreover, the interaction and viscous scenarios are studied for this model.

关键词： non-conserved gravity covariant form of thermodynamics holographic dark energy

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CFD predictions for hazardous area classification

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Chinese Journal of Chemical Engineering 2019年第1期27卷 21-31页

作者： Andrey Oliveira de Souza Aurélio Moreira Luiz ant?nio Tavernard Pereira Neto ant?nio Carlos Brandao de Araujo Heleno Bispo da Silva Sidinei Kebler da Silva Jose Jailson Nicacio Alves Federal Institute of Education Science and Technology of Paraiba Petrobras-Petróleo Brasileiro S.A. Federal University of Campina Grande

This study aimed to describe a Computational Fluid Dynamics(CFD) procedure using the ANSYS CFX software 16.1 and Design of Experiments for the determination of volume and extension of explosive atmospheres due to fugitive emissions of flammable *** multidimensional statistical sampling technique Latin Hypercube was used, which defined 100 simulations of random methane gas leak *** CFD model proved to be robust in predicting the extension and volume of the explosive atmosphere for orifice diameters from 0.1 to2.5 mm, pressure from 0.1 MPa to 12 MPa and temperatures from 0 ℃ to 400 ℃.It was found that the calculation domain must be parameterized 8 m in length for each millimeter of the diameter of the source of release to ensure the *** order not to lose precision for very small diameters, the mesh was parameterized with 50 elements along the orifice *** was proved that gravity does not influence the extension and volume of the explosive atmosphere at sonic *** deviation from the ideal gas behavior in the reservoir,achieved by applying the Soave–redlich–Kwong equation of state, also has not significantly influenced the extension and volume of the explosive *** results showed that the size of the explosive atmosphere varies directly with the diameter of the source emission and reservoir pressure, and inversely with the temperature of the *** diameter of the source is the parameter that has the major effect on the extension of the explosive atmosphere, followed by the pressure and lastly the temperature of the reservoir.

关键词： Computational Fluid Dynamics Computer simulation Safety Fugitive emissions Classified area Flammable gas cloud

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Cell-based therapeutic strategies for treatment of spinocerebellar ataxias:an update

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Neural regeneration research 2023年第6期18卷 1203-1212页

作者： Joana Sofia Correia Sara Duarte-Silva antónio JoséSalgado Patrícia Maciel Life and Health Sciences research Institute(ICVS) School of MedicineUniversity of MinhoBragaPortugal ICVS/3B’s–PT Government Associate Laboratory BragaGuimarãesPortugal

Spinocerebellar ataxias are heritable neurodegenerative diseases caused by a cytosine-adenine-guanine expansion,which encodes a long glutamine tract(polyglutamine)in the respective wild-type protein causing misfolding and protein *** features of polyglutamine spinocerebellar ataxias include neuronal aggregation,mitochondrial dysfunction,decreased proteasomal activity,and autophagy *** polyglutamine protein aggregates accumulate within neurons and cause neural dysfunction and death in specific regions of the central nervous *** ataxias are mostly characterized by progressive ataxia,speech and swallowing problems,loss of coordination and gait *** the past decade,efforts have been made to ameliorate disease symptoms in patients,yet no cure is *** studies have been proposing the use of stem cells as promising tools for central nervous system tissue *** far,pre-clinical trials have shown improvement in various models of neurodegenerative diseases following stem cell transplantation,including animal models of spinocerebellar ataxia types 1,2,and ***,contrasting results can be found in the literature,depending on the animal model,cell type,and route of administration ***,clinical trials using cellular implants into degenerated brain regions have already been applied,with the expectation that these cells would be able to differentiate into the specific neuronal subtypes and re-populate these regions,reconstructing the affected neural ***,the question of how feasible it is to continue such treatments remains unanswered,with long-lasting effects being still *** establish the value of these advanced therapeutic tools,it is important to predict the actions of the transplanted cells as well as to understand which cell type can induce the best outcomes for each *** studies are needed to determine the best route of administration,without neglec

关键词： cell transplantation engraftment induced pluripotent stem cells mesenchymal stem cells neural progenitor cells neuroprotection polyglutamine spinocerebellar ataxias secretome spinocerebellar ataxia stem cell therapy

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Investigating the impact of the universal function of the nuclear proximity potential in heavy-ion fusion cross sections

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Communications in Theoretical Physics 2024年第5期76卷 86-93页

作者： r Gharaei E Sarvari Department of Physics Sciences FacultyHakim Sabzevari UniversityPO Box 397SabzevarIran Department of Physics Faculty of ScienceFerdowsi University of MashhadPO Box 91775-1436MashhadIran Science Faculty Department of PhysicsTarbiat Modares UniversityTehranIran

The fusion barriers and cross sections of 15 colliding systems with 320≤Z_(1)Z_(2)≤1512 are investigated in detail to understand the influence of the universal function of proximity potential formalism in the heavy-ion fusion *** realize this goal,we select three versions of the phenomenological proximity potentials,including Prox.77,Zhang 2013,and Guo 2013,to calculate the nucleus-nucleus *** experimental fusion cross sections for the selected reactions are analyzed using the standard coupled-channel calculations,including couplings to the low-lying 2^(+)and 3^(-)states in the target and *** calculated results show that the universal functions of the Guo 2013 and Prox.77 models provide the lowest and highest fusion barriers,*** addition,it is found that the height of the fusion barriers is enhanced by increasing the mass number of the projectile from light to heavy *** highest sensitivity to the mass number of the projectile belongs to the results of Prox.77.A discussion is also presented on the influence of the universal function on the radial behavior of the interaction potential in the allowed region for overlapping *** results reveal that the best fit to the experimental data of the fusion cross sections for the reactions involving light and medium nuclei is obtained using the universal function of the Zhang 2013 *** the heavier systems,the results of the Guo 2013 model at sub-barrier energies provide a good description of the available data.

关键词： fusion reactions proximity-type potentials universal function coupled-channel calculations

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Mapping of quantitative trait loci using the skew-normal distribution

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2007年第11期8卷 792-801页

作者： FErNANDES Elisabete PACHECO antónio PENHA-GONALVES Carlos Centre for Mathematics and Its Applications IST-Technical University of Lisbon1049-001 LisboaPortugal Department of Statistics and Operational ResearchFaculty of SciencesUniversity of Lisbon1749-016 LisboaPortugal Gulbenkian Institute of ScienceP-2781-901 OeirasPortugal Department of Mathematics and Centre for Mathematics and Its Applications IST-Technical University of Lisbon1049-001 LisboaPortugal Gulbenkian Institute of Science P-2781-901 OeirasPortugal

In standard interval mapping (IM) of quantitative trait loci (QTL), the QTL effect is described by a normal mixture model. When this assumption of normality is violated, the most commonly adopted strategy is to use the previous model after data transformation. However, an appropriate transformation may not exist or may be difficult to find. Also this approach can raise interpretation issues. An interesting alternative is to consider a skew-normal mixture model in standard IM, and the resulting method is here denoted as skew-normal IM. This flexible model that includes the usual symmetric normal distribution as a special case is important, allowing continuous variation from normality to non-normality. In this paper we briefly introduce the main peculiarities of the skew-normal distribution. The maximum likelihood estimates of parameters of the skew-normal distribution are obtained by the expectation-maximization (EM) algorithm. The proposed model is illustrated with real data from an intercross experiment that shows a significant departure from the normality assumption. The performance of the skew-normal IM is assessed via stochastic simulation. The results indicate that the skew-normal IM has higher power for QTL detection and better precision of QTL location as compared to standard IM and nonparametric IM.

关键词： Interval mapping (IM) Quantitative trait loci (QTL) Skew-normal distribution Expectation-maximization (EM)algorithm

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Peripheral refraction of myopic eyes with spectacle lenses correction and lens free emmetropes during accommodation

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Eye and Vision 2021年第1期8卷 454-461页

作者： antónio Queirós Alejandro Cerviño JoséManuel González‑Méijome Clinical&Experimental Optometry research Lab(CEOrLab) Center of Physics(Optometry)University of MinhoCampus de Gualtar4710‑057 BragaPortugal Optometry research Group Department of Optics and Optometry and Vision SciencesUniversity of ValenciaValenciaSpain

Purpose:To measure axial and off-axis refraction patterns in myopic eyes with spectacle lenses correction and lens free emmetropes in young healthy subjects at different target distances from 2.00 m(0.50 D)to 0.20 m(5.00 D)in terms of sphere,astigmatism,and spherical equivalent ***:refraction was measured at the center,20 and 40 degrees from the line of sight both nasally and temporally in 15 emmetropic and 25 myopic young healthy subjects with an open field,binocular,infrared autorefractor(Grand Seiko WAM-5500,Hiroshima,Japan).Fixation target was a Maltese cross set at 2.00,0.50,0.33 and 0.20 m from the corneal *** in off-axis refraction with accommodation level were normalized with respect to distance axial values and compared between myopic eyes with spectacle lenses correction and lens free ***:Off-axis refraction in myopic eyes with spectacle lenses correction was significantly more myopic in the temporal retina compared to lens free emmetropes except for the closest target *** off-axis refractive error changed significantly with accommodation when compared to axial refraction particularly in the myopic *** change in the negative direction was due to changes in the spherical component of refraction that became more myopic relative to the center at the 0.20 m distance as the J0 component of astigmatism was significantly reduced in both emmetropes and myopes for the closest ***:Accommodation to very near targets(up to 0.20 m)makes the off-axis refraction of myopes wearing their spectacle correction similar to that of lens free emmetropes.A significant reduction in off-axis astigmatism was also observed for the 0.20 m distance.

关键词： Off-axis refraction refractive error Accommodation Myopia progression

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Combinatorial therapies for spinal cord injury: strategies to induce regeneration

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Neural regeneration research 2019年第1期14卷 69-71页

作者： Eduardo D.Gomes Nuno A.Silva antónio J. Salgado Life and Health Sciences research Institute (ICVS) School of Medicine University of Minho Campus de Gualtar ICVS/3B’s–PT Government Associate Laboratory

Spinal cord injury(SCI)is a condition without treatment,mainly characterized by the loss of motor and sensory function below the level of *** is accompanied by several complications such as cardiac and respiratory compromise,and often patients present psychological ailments associated with the drastic alteration of their normal *** pathophysiology derives from a massive damage to the spinal cord tissue,which is propagated

关键词：损害绳索新生治疗感觉功能生活方式星形细胞并发症

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Pile foundation in alternate layered liquefiable and non-liquefiable soil deposits subjected to earthquake loading

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 359-376页

作者： Praveen Huded M Suresh r Dash LEA Associates South East Asia Pvt.Ltd. New Delhi 110044India Indian Institute of Technology Bhubaneswar Khurda 752050India

Pile foundations are still the preferred foundation system for high-rise structures in earthquake-prone *** foundations have experienced failures in past earthquakes due to *** on pile foundations in liquefiable soils has primarily focused on the pile foundation behavior in two or three-layered soil ***,in natural occurrence,it may occur in alternative layers of liquefiable and non-liquefiable ***,the experimental and/or numerical studies on the layered effect on pile foundations have not been widely addressed in the *** of the design codes across the world do not explicitly mention the effect of sandwiched non-liquefiable soil layers on the pile *** the present study,the behavior of an end-bearing pile in layered liquefiable and non-liquefiable soil deposit is studied *** study found that the kinematic bending moment is higher and governs the design when the effect of the sandwiched non-liquefied layer is considered in the analysis as opposed to when its effect is ***,ignoring the effect of the sandwiched non-liquefied layer in a liquefiable soil deposit might be a nonconservative design approach.

关键词： pile foundation liquefaction alternately layered soil fixity effect layered effect

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