Parametric study of the convergence of deep tunnels with long term effects: Abacuses

Quevedo, Felipe P.M.,Bernaud, Denise Techno-Press 2018 Geomechanics & engineering Vol.15 No.4

The objective of this paper is to present abacuses obtained from a parametric study of deep-lined tunnels using a numerical finite element model. This numerical model was implemented in software GEOMEC91, which is a two-dimensional axisymmetric model that considers the progress of excavation and the placing of the lining through the activation and deactivation of elements. It is adopted a step of excavation constant (1/3 of radius), constant velocity and circular cross section along the tunnel axis. It is used for rock mass a viscoplastic constitutive law with von-Mises criterion of viscoplasticity without hardening whose deformation rate over time is given by the Bingham model. The lining uses a linear elastic constitutive law. In total are 1716 analysis presented in 60 abacuses that show the value of ultimate convergence ($U_{eq}$) due to tunneling speed. In addition, it is shown an example of the use of the abacuses to determine the ultimate convergence ($U_{eq}$) of the tunnel and pressure ($P_{eq}$) on the lining.

Curvature as a Measure of the Thermodynamic Interaction

Hernando Quevedo,Safia Taj,Alejandro V´azquez,Alberto S´anchez 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.31

We present a systematic and consistent construction of geometrothermodynamics by using Riemannian contact geometry for the phase manifold and harmonic maps for the equilibrium manifold. We present several metrics for the phase manifold that are invariant with respect to Legendre transformations and induce thermodynamic metrics on the equilibrium manifold. We review all the known examples in which the curvature of the thermodynamic metrics can be used as a measure of the thermodynamic interaction.

Degradation of Chrysanthemum (Dendranthema grandiflora) Wastes by Pleurotus ostreatus for the Production of Reducing Sugars

Balkys Quevedo-Hidalgo,Paulo César Narvaéz-Rincón,Aura Marina Pedroza-Rodríguez,Mario Enrique Velásquez-Lozano 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.5

In Colombia, a great amount of waste is generated during the cut-off and harvest stages in flowers culture. This study examines the possibility of degrading Chrysanthemum wastes by using Pleurotus ostreatus,Trametes versicolor, and Phanerochaete chrysosporium cultures; this has not been studied previously. The initial effect of fungi on the degradation of Chrysanthemum wastes were studied individually and in co-cultures. The highest degradation was by P. ostreatus. After that, the influence of pH and waste, copper, and manganese concentrations on reducing sugars concentration were determined in a submerged culture in 100 mL Erlenmeyer flasks. There was a significant effect of manganese and waste concentrations on sugar concentration, while the effect of copper concentration and pH were not significant. Following, the process was carried out in a 1.5 L reactor at the optimal values of the variables studied in Erlenmeyer flask but varying air injection from 0 to 2 vvm. The highest concentration of sugars was 21.2 g/L with 78% of glucose content at 6.3% w/v of waste, 7.5 mM of Mn and Cu and 2 vvm of air injection. Finally, laccase, Manganese peroxidase, endo-1,4-β-glucanase, exo-1,4-β-glucanase and 1,4-β-glucosidase were detected in the extract obtained under these conditions. The highest activities were obtained for laccase (4,694 U/L) and 1,4-β-glucosidase (9,513 U/L).

Arm-like Mechanism User Interface for 3D Animation

Alvaro Uribe-Quevedo,Hernando Leon,Byron Perez-Gutierrez 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10

Character animation is traditionally accomplished using traditional input devices such as keyboards, mouse, joysticks, programming pads or motion capture systems with elevated costs making them unavailable to common users. However, 3D User Interfaces such as electromechanical sensors, depth maps and vision tracking have been changing how we interact with information in several applications and common use devices. Animation using 3D user interfaces allows more natural, fluent and precise queues of motion, which is why this work presents the implementation of an anthropomorphic mechanism for motion capture through flexion/extension and abduction/adduction with an arm mechanism of four Degrees of Freedom. The goal is to present the feasibility of assembling a low cost device that allows tracking suitable motion for performing an animation on a virtual character.

Finite element modeling of manufacturing irregularities of porous materials

Gonzalez, Fernando J. Quevedo,Nuno, Natalia Techno-Press 2016 Biomaterials and Biomechanics in Bioengineering Vol.3 No.1

Well-ordered porous materials are very promising in orthopedics since they allow tailoring the mechanical properties. Finite element (FE) analysis is commonly used to evaluate the mechanical behavior of well-ordered porous materials. However, FE results generally differ importantly from experimental data. In the present article, three types of manufacturing irregularities were characterized on an additive manufactured porous titanium sample having a simple cubic unit-cell: strut diameter variation, strut inclination and fractured struts. These were included in a beam FE model. Results were compared with experimental data in terms of the apparent elastic modulus (Eap) and apparent yield strength (SY,ap). The combination of manufacturing irregularities that yielded the closest results to experimental data was determined. The idealized FE model resulted in an Eap one order of magnitude larger than experimental data and a SY,ap almost twice the experimental values. The strut inclination and fractured struts showed the strongest effects on Eap and SY,ap, respectively. Combining the three manufacturing irregularities produced the closest results to experimental data. The model also performed well when applied to samples having different structural dimensions. We recommend including the three proposed manufacturing irregularities in the FE models to predict the mechanical behavior of such porous structures.

Finite element modeling of manufacturing irregularities of porous materials

Gonzalez, Fernando J. Quevedo,Nuno, Natalia Techno-Press 2016 Biomaterials and biomedical engineering Vol.3 No.1

Well-ordered porous materials are very promising in orthopedics since they allow tailoring the mechanical properties. Finite element (FE) analysis is commonly used to evaluate the mechanical behavior of well-ordered porous materials. However, FE results generally differ importantly from experimental data. In the present article, three types of manufacturing irregularities were characterized on an additive manufactured porous titanium sample having a simple cubic unit-cell: strut diameter variation, strut inclination and fractured struts. These were included in a beam FE model. Results were compared with experimental data in terms of the apparent elastic modulus (Eap) and apparent yield strength (SY,ap). The combination of manufacturing irregularities that yielded the closest results to experimental data was determined. The idealized FE model resulted in an Eap one order of magnitude larger than experimental data and a SY,ap almost twice the experimental values. The strut inclination and fractured struts showed the strongest effects on Eap and SY,ap, respectively. Combining the three manufacturing irregularities produced the closest results to experimental data. The model also performed well when applied to samples having different structural dimensions. We recommend including the three proposed manufacturing irregularities in the FE models to predict the mechanical behavior of such porous structures.

Beneficial Effects of Fructooligosaccharides Esterified with Lauric Acid in a Metabolic Syndrome Model Induced by a High-Fat and High-Carbohydrate Diet in Wistar Rats

Susana Herna´ndez-Pe´rez,Rosa Marı´a Oliart-Ros,Leticia Casas-Godoy,Georgina Sandoval,Veronica Guarner Lans,Vicente Castrejo´n-Te´llez,Lucı´a Quevedo-Corona,Lucı´a Quevedo-Corona,Carolina Pen˜a-Montes 한국식품영양과학회 2022 Journal of medicinal food Vol.25 No.8

Metabolic syndrome (MS) is a group of abnormalities in which obesity, insulin resistance (IR), oxidative stress, and dyslipidemia stand out. This pathology predisposes to the development of cardiovascular diseases and diabetes. The ingestion of linear fructooligosaccharides (FOS) such as inulin reduces conditions such as hyperinsulinemia, increased body fat, and triglyceridemia. When FOS are esterified with fatty acids, they present emulsifying and surfactant properties; however, there are no reports of their function at the biological level. The purpose of this investigation was to evaluate the effect of Agave tequilana Weber's FOS (AtW-FOS) and FOS esterified with lauric acid (FOS-LA) in MS markers in a rat model induced by a HFHC diet. Supplementation with AtW-FOS and FOS-LA decreased IR, improved glucose tolerance, reduced liver weight (19%), plasma triglycerides (24%), and blood pressure (16%) when compared with the untreated MS group. In conclusion, the ingestion of AtW-FOS and FOS-LA has beneficial effects in the prevention of MS alterations, showing a high potential for their application in functional foods.

Cascade random-quasi-phase-matched harmonic generation in polycrystalline ZnSe

Kupfer, R.,Quevedo, H. J.,Smith, H. L.,Lisi, L. A.,Tiwari, G.,Richmond, C. G.,Bowers, B. B.,Fang, L.,Hegelich, B. M. American Institute of Physics 2018 JOURNAL OF APPLIED PHYSICS - Vol.124 No.24

Effect of processing route on mechanical and thermal properties of few-layered graphene (FLG)-reinforced copper matrix composites

Jang, Haneul,Yoo, Seonghyeon,Quevedo, Manuel,Choi, Hyunjoo Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.754 No.-

<P><B>Abstract</B></P> <P>In this study, copper/few-layered graphene (Cu/FLG) composite powder is prepared using two different approaches, chemical synthesis and mechanical milling, and the effect of the processing routes on the mechanical and thermal behaviors of hot-pressed pallets is examined. With both processing routes, the strength of the matrix is increased ∼3.90 and ∼2.82 times by grain refinement, and is further increased 1.14 times by incorporating 0.5 vol.% FLG. In addition, for both processing routes, the coefficient of thermal expansion is reduced from ∼17.07 to ∼15.15 (ppm/K) by incorporating 0.5 vol.% of FLG in both composites. Considering its cost-effectiveness, simplicity, and potential for mass-production, the mechanical process demonstrates the ability to produce Cu/FLG composites with a high mechanical and thermal performance that is comparable to solution-based chemical synthesis routes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Copper/few-layered graphene (FLG) composite is prepared by two methods of chemical synthesis and mechanical milling. </LI> <LI> The effect of processing routes on the mechanical and thermal behaviors of composites is examined. </LI> <LI> FLG is found to be effective to increase mechanical and thermal properties of composites regardless of processing routes. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Stable temperature coefficient of resistance in TiSiON thin film resistors deposited by magnetron co-sputtering

Marcela Mireles,,M.A. Quevedo Lopez 한국물리학회 2016 Current Applied Physics Vol.16 No.11

Thin films of titanium/silicon (Ti:Si) are widely employed in the electronics industry because of their metal-like characteristics. The use of films as thin film resistor (TFR) based on Ti:Si has not yet been reported. In this paper, the TFR characteristics of TiSiON with different compositions and deposited in Argon atmosphere with either 1% Oxygen or 1% Oxygen/3% Nitrogen are studied. The film composition was varied through a co-sputtering approach from titanium and silicon targets and the sheet resistance (Rsh) and temperature coefficient of resistance (TCR) were evaluated. The film composition was evaluated by X-ray photoelectron spectroscopy (XPS); carrier mobility, type and concentration by Hall effect methods and film microstructure by X-Ray diffraction. Nitrogen addition during the deposition reduces oxidized species in the TFR and increases film stability. The addition of nitrogen results in TFR films with partially oxidized titanium and silicon and TFR values closer to zero TCR without impacting film resistance. Films deposited without nitrogen result in more unstable films and larger TCR. A near-zero TCR film was found for a Ti:Si ratio of 1.6, exhibiting a Rsh at 25 C of 0.7 kOhms with a TCR value of 171 ppm/C after annealing at 450 C in forming gas.