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Strength design criterion for asymmetrically reinforced RC circular cross-sections in bending
E. Hernández-Montes,L.M. Gil-Martín,P. Alameda-Hernández 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.11 No.6
Asymmetrical reinforcement for circular sections in wall piles is an efficient construction component with reduced embodied energy. It has been proven that asymmetrical reinforced wall piles may save more than 50% of the reinforcement than the traditional symmetrically reinforced circular sections. The use of this new type of structural member increases the number of variables in the design problem, which makes its use by engineers more complicated. In order to facilitate the use of the asymmetrically reinforced piles, this paper presents a criterion for the design of this type of structural member. The chosen criterion has been analyzed with the help of flexural capacity-cost curves. The new criterion is similar to the design procedure traditionally used for RC beams.
Curcumin-loaded Polycaprolactone/Collagen Composite Fibers as Potential Antibacterial Wound Dressing
E. San Martín-Martínez,Casañas-Pimentel,A. Almaguer-Flores,G. Prado-Prone,A. García-García,C. Landa-Solís,A. Hernández-Rangel 한국섬유공학회 2022 Fibers and polymers Vol.23 No.11
The development of wound dressings with therapeutical benefits is of great importance in skin tissue engineeringapplications, adding bioactive molecules into biomaterials is a strategy to achieve a better biological response. In this study,four different concentrations of curcumin (CUR; 5, 10, 15 and 20 by weight in relation to the PCL content) were incorporatedinto solutions composed of polycaprolactone (PCL) and collagen (COL) for the manufacture of electrospun fibers. The PCLCOL-CUR fibers were physicochemically characterized in terms of their morphology, wettability, degradation rate,mechanical behavior, and cumulative curcumin release. The in vitro biological properties of the composite membranes werealso evaluated. The results indicated that the membranes have diameters on average of approximately 200 nm. The wateruptake was adequate for exudates remotion in a wound, and the degradation rate of the fibers was highly appropriate toachieve complete skin tissue regeneration. The addition of CUR to composite membranes produced a significant increase inthe mechanical properties which indicate a satisfactory clinical handling. The incorporation of CUR produced a significantdecrease in the planktonic growth of S. aureus over time, however, the antibacterial effect against E. coli was limited, thepresence of CUR did not cause the inhibition of its growth. Finally, the viability of human dermal fibroblasts seeded on thetop of the membranes indicated the cytotoxic dosage effect of CUR, the two highest CUR concentrations produced asignificant loss of cell viability. Overall, our results suggested that the CUR-loaded PCL-COL composite membranes arepromising candidates for use as antibacterial dressings to enhance clinical wound management.
Ricardo Martínez-Alvarado,Everardo Efrén Granda-Gutiérrez,Alejandra Hernández-Rodríguez,Rolando Javier Praga-Alejo 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.10
A pulse classification technique for monitoring the type of discharges in an electrochemical discharge machining (ECDM) process is presented in this research paper. The performance of an ECDM process is affected by many factors which make it hard for control strategies to be formulated for this process. The pulse classifier plays an important role to develop control strategies and later to improve the process. The proposed system uses the current and voltage waveforms measured through the gap as input signals for the classification system. A fuzzy inference system (FIS) is used to categorize both input signals into one of the four proposed pulse types, according to their specific behavior. For the experimental validation, data samples taken during the machining process were recorded to evaluate the performance of the pulse classifier with raw data. Raw data of the gap signals is properly classified based on the proposed FIS.
Gregorio Iraola,Martín Hernández,Lucía Calleros,Fernando Paolicchi,Silvia Silveyra,Alejandra Velilla,Luis Carretto,Eliana Rodríguez,Ruben Pérez 대한수의학회 2012 JOURNAL OF VETERINARY SCIENCE Vol.13 No.4
Campylobacter (C.) fetus (epsilonproteobacteria) is an important veterinary pathogen. This species is currently divided into C. fetus subspecies (subsp.) fetus (Cff) and C. fetus subsp. venerealis (Cfv). Cfv is the causative agent of bovine genital Campylobacteriosis, an infectious disease that leads to severe reproductive problems in cattle worldwide. Cff is a more general pathogen that causes reproductive problems mainly in sheep although cattle can also be affected. Here we describe a multiplex PCR method to detect C. fetus and differentiate between subspecies in a single step. The assay was standardized using cultured strains and successfully used to analyze the abomasal liquid of aborted bovine fetuses without any pre-enrichment step. Results of our assay were completely consistent with those of traditional bacteriological diagnostic methods. Furthermore, the multiplex PCR technique we developed may be easily adopted by any molecular diagnostic laboratory as a complementary tool for detecting C. fetus subspecies and obtaining epidemiological information about abortion events in cattle.
Fluid-structure interaction of a tensile fabric structure subjected to different wind speeds
Jesús G. Valdés-Vázquez,Adrián D. García-Soto,Alejandro Hernández-Martínez,José L. Nava 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.31 No.6
Despite the current technologic developments, failures in existent tensile fabric structures (TFS) subjected to wind do happen. However, design pressure coefficients are only obtained for large projects. Moreover, studies on TFSs with realistic supporting frames, comparing static and dynamic analyses and discussing the design implications, are lacking. In this study, fluid-Structure analyses of a TFS supported by masts and inclined cables, by subjecting it to different wind speeds, are carried out, to gain more understanding in the above-referred aspects. Wind-induced stresses in the fabric and axial forces in masts and cables are assessed for a hypar by using computational fluid dynamics. Comparisons are carried out versus an equivalent static analysis and also versus loadings deemed representative for design. The procedure includes the so-called form-finding, a finite element formulation for the TFS and the fluid formulation. The selected structure is deemed realistic, since the supporting frame is included and the shape and geometry of the TFS are not uncommon. It is found that by carrying out an equivalent static analysis with the determined pressure coefficients, differences of up to 24% for stresses in the fabric, 5.4% for the compressive force in the masts and 21% for the tensile force in the cables are found with respect to results of the dynamic analysis. If wind loads commonly considered for design are used, significant differences are also found, specially for the reactions at the supporting frame. The results in this study can be used as an aid by designers and researchers.
Jorge Chávez,Omar Jiménez Alemán,Martín Flores Martínez,Héctor J. Vergara‑Hernández,Luis Olmos,Pedro Garnica‑González,Didier Bouvard 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.2
The design and fabrication of a bilayer Ti6Al4V–Ti6Al4V/30Ta component were performed by using the powder metallurgyprocess and solid-state sintering as the consolidation step. Phase change and sintering densifcation of the component werestudied by dilatometry. The addition of 30 vol% of Ta to the Ti6Al4V matrix had a noticeable efect over the microstructuraland mechanical properties of the alloy, which showed decrements of up to 12.2 and 21.5% in nano-hardness and elastic modulus, respectively. The decrement of these properties strongly afected the wear and corrosion performance of the component. Special attention was focused on the intermediate zone between layers denoted by a transition zone, which presented betterwear response because of the properties and microstructure caused by the gradient difusion of Ta. Ti6Al4V/30Ta alloyshowed an improved corrosion behaviour compared to Ti6Al4V alloy, decreasing 2.4 times their susceptibility to corrosionand about two orders of magnitude their corrosion rate. The bilayer component in this study is proposed as an alternative todecrease the consumption of expensive materials with improved properties.
Prediction-observer Scheme for Linear Systems with Input-output Time-delay
Varinia Fragoso-Rubio,Martín Velasco-Villa,Miguel A. Hernández-Pérez,Basilio del Muro-Cuéllar,Juan Francisco Márquez-Rubio 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.8
This work deals with the prediction and control problems associated with a class of linear systems with time-delay at the input-output path. A general prediction observer scheme that estimates the future value of the delayed system from the output is proposed. Later, a full-information predictor-observer is introduced and the convergence of the estimated future values is formally proven for a time-delay τ of any size by increasing the dimension of the proposed predictor-observer. The estimated future state is used to design a feedback law that compensates the delay effects on the original system. The performance of the prediction-observation control strategy is shown by means of numerical simulations. Thus, it is illustrated that the performance of the proposed full-information predictor-observer is improved with respect to the sequential sub-predictors previously presented in the literature.
Romero-Garay Martha Guillermina,Martínez-Montaño Emmanuel,Hernández-Mendoza Adrián,Vallejo-Cordoba Belinda,González-Córdova Aarón Fernando,Montalvo-González Efigenia,García-Magaña María de Lourdes 한국응용생명화학회 2020 Applied Biological Chemistry (Appl Biol Chem) Vol.63 No.4
In the present study, we evaluated new sources of plant proteases from fruits of Bromelia karatas (BK) and Bromelia pinguin (BP) to obtain antioxidant hydrolyzates/bioactive peptides (BPs) derived from chicken by-products (CH) and fish by-products (FH). The profile of the peptides was identified by reverse-phase high-resolution liquid chromatography (RP-HPLC) and the size weight distribution by molecular exclusion chromatography (SEC). The hydrolysates obtained with BK in both sources of by-products showed greater antioxidant capacity compared to those obtained with BP, presenting similar or higher values when compared to a commercial plant enzyme. The use of new sources of plant proteases allowed to obtain hydrolysates of hydrophilic character with a high percentage (> 50%) of peptides with molecular weights < 17.5 kDa from chicken and fish by-products. Therefore, based on the results obtained in antioxidant capacity it is possible to consider the hydrolysates as potential ingredients, food additives, and pharmaceutical products.
The buried arch structural system for underground structures
Mark Aschheim,Luisa María Gil-Martín,Enrique Hernández-Montes 국제구조공학회 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.20 No.1
In many cases, underground structures are built using conventional above-grade structural systems to carry gravity load. This paper proposes the use of underground arches, termed “buried arches”, to support gravity loads, wherein the horizontal thrust of the arch is equilibrated by soil pressure. Because the horizontal soil pressure increases with depth, the depth of the arch may be reduced as the depth below grade increases. Critical to the success of such an approach is a proper accounting of creep and shrinkage for arches made of reinforced concrete. This paper addresses the influence of equilibrium, creep, and shrinkage as they affect the design of the arch from a theoretical perspective. Several examples illustrate the use of buried arches for the design of underground parking structures.