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Modeling and simulation of normal and hemiparetic gait

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Frontiers of Mechanical Engineering 2015年第3期10卷 233-241页

作者： Lely A. LUENGAS esperanza CAMARGO Giovanni SANCHEZ Technological Faculty Universidad Distrital Francisco Jose de CaldasBogota Colombia Engineering Faculty Universidad de San Buenaventura BogotaColombia

Gait is the collective term for the two types of bipedal locomotion, walking and running. This paper is focused on walking. The analysis of human gait is of interest to many different disciplines, including biomecha- nics, human-movement science, rehabilitation and medicine in general. Here we present a new model that is capable of reproducing the properties of walking, normal and pathological. The aim of this paper is to establish the biomechanical principles that underlie human walking by using Lagrange method. The constraint forces of Rayleigh dissipation function, through which to consider the effect on the tissues in the gait, are included. Depending on the value of the factor present in the Rayleigh dissipation function, both normal and pathological gait can be simulated. First of all, we apply it in the normal gait and then in the permanent hemiparetic gait. Anthropometric data of adult person are used by simulation, and it is possible to use anthropometric data for children but is necessary to consider existing table ofanthropometric data. Validation of these models includes simulations of passive dynamic gait that walk on level ground. The dynamic walking approach provides a new perspective of gait analysis, focusing on the kinematics and kinetics of gait. There have been studies and simulations to show normal human gait, but few of them have focused on abnormal, especially hemiparetie gait. Quantitative comparisons of the model predictions with gait measurements show that the model can reproduce the significant characteristics of normal gait.

关键词： bipedal gait biomechanics dynamic walking,gait model human gait hemiparetic human gait

TWO NOVEL GRADIENT METHODS WITH OPTIMAL STEP SIZES

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Journal of Computational Mathematics 2021年第3期39卷 375-391页

作者： Harry Oviedo Oscar Dalmau Rafael herrera Centro de Investigacion en Matematicas CIMAT A.C.GuanajuatoGto.Mexico

In this work we introduce two new Barzilai and Borwein-like steps sizes for the classical gradient method for strictly convex quadratic optimization *** proposed step sizes employ second-order information in order to obtain faster gradient-type *** step sizes are derived from two unconstrained optimization models that involve approximate information of the Hessian of the objective function.A convergence analysis of the proposed algorithm is *** numerical experiments are performed in order to compare the efficiency and effectiveness of the proposed methods with similar methods in the ***,it is observed that our proposals accelerate the gradient method at nearly no extra computational cost,which makes our proposal a good alternative to solve large-scale problems.

关键词： Gradient methods Convex quadratic optimization Hessian spectral properties Steplength selection

Synsepalum dulcificum extracts exhibit cytotoxic activity on human colorectal cancer cells and upregulate c-fos and c-jun early apoptotic gene expression

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Asian Pacific Journal of Tropical Biomedicine 2018年第3期8卷 173-178页

作者： Jichang Seong Glenn G.Oyong esperanza C.Cabrera Biology Department De La Salle University Molecular Science Unit Laboratory Center for Natural Science and Environmental Research De La Salle University

Objective: To explore cytotoxicity of Synsepalum dulcificum(S. dulcificum) Daniell(Sapotaceae) on human colon cancer(HCT-116 and HT-29), human monocytic leukemia(THP-1) and normal(HDFn) cell lines, and its effect on the expression of early apoptotic genes, c-fos and c-jun. Methods: Leaf, stem and berry of S. dulcificum were separately extracted by using 2 solvents, 10% ethanol(EtOH) and 80% methanol(MeOH). PrestoB lue~? cell viability assay and q RT-PCR assay were conducted to examine the above objectives respectively. Results: Stem MeOH, stem EtOH, and berry EtOH extracts of S. dulcificum were cytotoxic to HCT-116 and HT-29 human colon cancer cells. For HCT-116, IC_(50) values of these 3 extracts were not significantly different(P>0.05) from that of the positive control bleomycin(IC_(50) of 33.57 μg/mL), while for HT-29, IC_(50) values of these 3 extracts were significantly lower(P<0.05) than that of bleomycin(IC_(50) of 25.24 μg/mL). None of the extracts were cytotoxic to the THP-1 monocytic leukemia cells and HDFn normal human dermal fibroblasts. For both HCT-116 and HT-29, these extracts significantly up-regulated(P<0.05) the expression of c-fos and c-jun compared to the untreated negative control. Conclusions: The results of this study suggest that cytotoxicity of stem MeOH, stem EtOH, and berry EtOH extracts of S. dulcificum on HCT-116 and HT-29 colon cancer cells is due to the induced apoptosis which is caused by the up-regulation of the expression of early apoptotic genes, c-fos and c-jun.

关键词： Synsepalum dulcificum Colon cancer Monocytic leukemia Apoptosis c-fos c-jun

Identification of boundary surfaces in flows

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Applied Mathematics and Mechanics(English Edition) 2010年第9期31卷 1097-1104页

作者： B.herrera J.PALLARES Department d'Enginyeria Informàtica i Matematiques Universitat Rovira i VirgiliAvinguda Pasos Catalans 26Tarragona 43007Spain Department d'Enginyeria Mecànica Universitat Rovira i VirgiliAvinguda Pasos Catalans 26Tarragona 43007Spain

In this study, boundary surfaces of a flow field are defined as stream surfaces, on which the shear rates vanish, and a procedure is proposed to find them. The method, based on calculations using the velocity vector f... 详细信息

关键词： interracial surfaces structure of flow kinematics

Human Interaction Dynamics for Its Use in Mobile Robotics:Impedance Control for Leader-follower Formation

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IEEE/CAA Journal of Automatica Sinica 2017年第4期4卷 696-703页

作者： Daniel herrera Flavio Roberti Marcos Toibero Ricardo Carelli Instituto de Automatica Universidad Nacional de San Juan-CONICET IEEE

A complete characterization of the behavior in human-robot interactions(HRI) includes both: the behavioral dynamics and the control laws that characterize how the behavior is regulated with the perception data. In this way, this work proposes a leader-follower coordinate control based on an impedance control that allows to establish a dynamic relation between social forces and motion error. For this, a scheme is presented to identify the impedance based on fictitious social forces, which are described by distance-based potential *** part of the validation procedure, we present an experimental comparison to select the better of two different fictitious force structures. The criteria are determined by two qualities: least impedance errors during the validation procedure and least parameter variance during the recursive estimation ***, with the best fictitious force and its identified impedance,an impedance control is designed for a mobile robot Pioneer 3AT,which is programmed to follow a human in a structured *** to results, and under the hypothesis that moving like humans will be acceptable by humans, it is believed that the proposed control improves the social acceptance of the robot for this kind of interaction.

关键词： Human modeling human-machine interaction impedance control robot dynamics social robotics

RANS feasibility study of using roughness to mimic transition strip effect on the crossflowseparation over a 6:1 prolate-spheroid

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Journal of Hydrodynamics 2019年第3期31卷 570-581页

作者： Mojtaba M. Amiri Marcelo A. Vitola Sergio H. Sphaier, Paulo T. esperanza Ocean Technology Laboratory (LabOceano-COPPE) Federal University of Rio de Janeiro Rio de Janeiro RJ 21941-907 Brazil

An axisymmetric body at incidence experiences the three-dimensional crossflow separation. This separation is attributed to the adverse circumferential pressure gradient. However, the separation pattern is also dependent upon the structure of the boundary layer. In this regard, utilization of transition strip devices in experiments on axisymmetric bodies may modify this structure, and consequently the crossflow separation pattern. The main objective of the present research is to mimic numerically the transition strip effect on the crossflow separation over a 6:1 prolate-spheroid up to a = 30° incidence and ReL = 4.2 x 10&. However, to avoid direct modeling of the strip, which would increase the computational cost, an attempt was made to add roughness over the body surface. To estimate the roughness that simulates closely the transition strip effect, three different roughness values were considered. The numerical model is based on RANS and a Reynolds stress turbulence model implemented in STARCCM+. The simulations have been evaluated based on the local and global variables and validated against the available experimental data. The results demonstrate the effectiveness of using a proper roughness value to mimic the transition strip effect. They also show the importance of modeling the transition strip effect, which is normally not taken into account, to capture the crossflow separation pattern.

关键词： Axisymmetric body crossflow separation transition strip device CFD RANS equations

Geomorphic indices and relative tectonic uplift in the Guerrero sector of the Mexican forearc

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Geoscience Frontiers 2017年第4期8卷 885-902页

作者： Krzysztof Gaidzik María Teresa Ramírez-herrera Laboratorio Universitario de Geofísica Ambiental & Instituto de Geografía Universidad Nacional Autónoma de MéxicoCiudad Universitaria Berkeley Seismological Laboratory Department of Earth and Planetary ScienceUniversity of California Berkeley

Tectonically active areas,such as forearc regions,commonly show contrasting relief,differential tectonic uplift,variations in erosion rates,in river incision,and in channel gradient produced by ongoing tectonic ***,information on the tectonic activity of a defined area could be derived via landscape *** study uses topography and geomorphic indices to extract signals of ongoing tectonic deformation along the Mexican subduction forearc within the Guerrero *** this purpose,we use field data,topographical data,knickpoints,the ratio of volume to area（Rva）.the stream-length gradient index（St）,and the normalized channel steepness index（k_（sn））.The results of the applied landscape analysis reveal considerable variations in relief,topography and geomorphic indices values along the Guerrero sector of the Mexican subduction *** argue that the reported differences are indicative of tectonic deformation and of variations in relative tectonic uplift along the studied forearc.A significant drop from central and eastern parts of the study area towards the west in values of R_（VA）（from ~500 to^300）,St（from ~500 to ca.400）,maximum St（from ~1500-2500 to ~ 1000） and k_（sn）（from ~150 to ~100） denotes a decrease in relative tectonic uplift in the same *** suggest that applied geomorphic indices values and forearc topography are independent of climate and *** mechanisms responsible for the observed variations and inferred changes in relative forearc tectonic uplift call for further studies that explain the physical processes that control the forearc along strike uplift variations and that determine the rates of *** proposed methodology and results obtained through this study could prove useful to scientists who study the geomorphology of forearc regions and active subduction zones.

关键词： Relative tectonic uplift Forearc Active tectonics Geomorphic index Drainage network Mexican subduction zone

Comparison between linseed expeller and canola expeller on concentrate intake,and circulating inflammatory mediators in Holstein calves

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Animal Nutrition 2020年第1期6卷 47-53页

作者： Pedro melendez Romina Ramirez Maria P.Marin Mario Duchens Pablo Pinedo College of Veterinary Medicine University of GeorgiaTiftonGA31793USA College of Veterinary Medicine University Santo TomasVina del MarChile College of Veterinary Medicine University of ChileSantiagoChile Department of Animal Sciences Colorado State UniversityFort CollinsCO80523USA College of Veterinary Medicine University of MissouriColumbiaMO 61203USA

The objective of this study was to compare the effect of linseed and canola expeller on average daily weight gain(ADG),concentrate intakes,incidence of diarrhea,serum haptoglobin,interleukin(IL)-1,and resolvin-E1 in female Holstein calves from birth to weaning.A sample size of 20 calves per group was calculated and were randomly allocated at the time of *** group(LIN)was fed a starter with linseed expeller,while canola group(CAN)received a similar concentrate,but with canola *** expellers were included at a rate of 25%dry matter(DM)basis of the *** waste milk was fed twice a day until *** were weighed at birth,30,and 60 d of *** intake was evaluated daily from 5 to 60 d.A blood sample was obtained at birth,14,28,35,and 49 d of age,and bovine serum resolvin-El,haptoglobin,and IL-1 were assayed by commercial enzyme-linked immunosorbent assay(ELISA)*** of diarrhea and the duration of the events were also *** effect of the interaction group by time on body weight(BW)and starter intake was not significant(P>0.05).Average daily gains(ADG)from 0 to 60 d for CAN and LIN groups were 0.680 and 0.675 kg/d(P>0.05),*** of diarrhea were 25%and 45%for CAN and LIN groups,respectively(P=0.18).LIN group had greater concentrations of IL-1 at d 21,haptoglobin at d 7,and resolving-El at d 14 and 49 than CAN group,*** is concluded that BW at weaning,ADG,and concentrate intakes were not different between groups fed starters containing linseed or canola expeller(25%inclusion).The concentrations of cytokines and haptoglobin were the greatest in LIN group.

关键词： Linseed expeller Omega-3 fatty acids Calf Daily gain Diarrhea

Wavelet-based deconvolution of ultrasonic signals in nondestructive evaluation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第10期7卷 1748-1756页

作者： herrera Roberto Henry OROZCO Rubén RODRIGUEZ Manuel Department of Informatics University of Cienfuegos Cienfuegos 59430 Cuba CEETI Central University of Las Villas Santa Clara 54830 Cuba Department of Physics Central University of Las Villas Santa Clara 54830 Cuba

In this paper, the inverse problem of reconstructing reflectivity function of a medium is examined within a blind deconvolution framework. The ultrasound pulse is estimated using higher-order statistics, and Wiener filter is used to obtain the ultrasonic reflectivity function through wavelet-based models. A new approach to the parameter estimation of the inverse filtering step is proposed in the nondestructive evaluation field, which is based on the theory of Fourier-Wavelet regularized deconvolution (ForWaRD). This new approach can be viewed as a solution to the open problem of adaptation of the ForWaRD framework to perform the convolution kernel estimation and deconvolution interdependently. The results indicate stable solutions of the esti- mated pulse and an improvement in the radio-frequency (RF) signal taking into account its signal-to-noise ratio (SNR) and axial resolution. Simulations and experiments showed that the proposed approach can provide robust and optimal estimates of the reflectivity function.

关键词： Blind deconvolution Ultrasonic signals processing Wavelet regularization