A Linear Approach for Sizing Optimization of Isostatic Trussed Structures Subjected to External and Self-Weight Loads

Flavio Avila Correia Martins,Juan Pablo Julca Avila,Marcelo Araujo da Silva 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.4

The implementation of a new linear method to optimum weight design of trussed structures subjected to external and selfweight loads is proposed. Design variables are the cross-section areas of the members. Inequality constraints are written based on the force-method for isostatic structures considering maximum and minimum axial stress criteria. The novelty of the proposed approach is the benefi t created from the combination of a linear inequality-constrained formulation with interior-point methods to tunnel the solution rapidly and monotonically towards the minimum value through feasible space, also eliminating the need to directly explore the fi nite-element model. To evaluate the performance of the algorithm, trusses are subject to optimization processes based on diff erent techniques: (i) the proposed method, called by “indirect-method”; (ii) a design problem with constraint evaluated directly from the fi nite-element model; (iii) optimization based on Genetic Algorithms. The three methods are compared using trusses with 10, 37 and 1240 bar-elements. The results showed that the indirect-method was able to provide great performance for complex topologies, returning weight designs up to 70 times lighter in 1% of the time required by a Genetic Algorithm.

Diffusion and competitive relationship of mobile telephone service in Guatemala: An empirical analysis

Avila, Luz Angelica Pirir,Lee, Deok-Joo,Kim, Taegu Elsevier 2018 TelecommunicationsPolicy Vol.42 No.2

<P><B>Abstract</B></P> <P>The purpose of this paper is to analyze the characteristics of diffusion process of mobile telephone service and the competitive relationships between mobile and fixed-line services in Guatemalan telecommunications market. We investigated the best-suited model to explain the diffusion process of mobile telephone in Guatemala by estimating diffusion curves using empirical data. Moreover, we explored affecting factors which characterize the diffusion pattern of mobile telephony in Guatemala through statistical analysis. Finally, in order to understand the effects of competition in the diffusion process of Guatemalan mobile phone service, we attempted to clarify the competitive relationship between mobile and fixed-line services using the Lotka-Volterra model. As a result, the logistic model was found to be the best model for describing the diffusion pattern. Moreover, investment in telecommunications, the subscribers of fixed-line services, and the number of operators in mobile market were found as significant determinants of mobile diffusion process. Results from the Lotka-Volterra model showed that the relationship between mobile and fixed-line services has changed from pure competition to amensalism.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The characteristics of diffusion process of mobile telephone service and the competitive relationships between mobile and fixed-line services in Guatemalan telecommunications market are analyzed. </LI> <LI> The logistic model is the best model for describing the diffusion pattern of mobile phone in Guatemala. </LI> <LI> Investment, fixed-line subscribers, and the number of operators are significant determinants of the diffusion rate of mobile phone in Guatemala. </LI> <LI> The relationship between mobile and fixed-line services has changed from pure competition to amensalism in Guatemala. </LI> </UL> </P>

A new record of Feldmannia chitonicola from Korea based on laboratory culture and molecular data

Avila-Peltroche, Jose,Oteng'o, Antony Otinga,Jeong, So Young,Won, Boo Yeon,Cho, Tae Oh Korean Society of Environmental Biology 2019 환경생물 : 환경생물학회지 Vol.37 No.3

Feldmannia chitonicola is reported as a new record from Korea based on morphological studies in laboratory-cultured materials and molecular analyses. F. chitonicola is mainly characterized by a small size (1-2 mm), erect filaments mostly unbranched, plurilocular sporangia produced on both prostrate and laterally on the basal part of erect filaments, and 2 types (lanceolate and ovate) of sporangia. In our cultures, sporangia production was slower at 10℃ than in 16℃ and 20℃. Our molecular analyses of rbcL and cox1 genes supported its independence from other congeners reported for Korea. This is the first report of F. chitonicola for western Pacific.

Interaction between quinclorac and imidazolinones in the control of resistant Cyperus iria to ALS inhibitors

Avila Neto Roberto Costa,de Souza Pablo Mazzuco,Rubert Jaine,Seibt Tiago André,Thomasi Rosana Marzari,Melo Adriano Arrué,Alves Marcelo Plada,da Rosa Ulguim André 한국작물학회 2023 Journal of crop science and biotechnology Vol.26 No.2

Herbicides belonging to the chemical group imidazolinones and the quinclorac herbicide are important to control weeds in fooded rice. The objective of this research was to evaluate the interaction of imidazolinones with quinclorac to control Cyperus iria resistant to acetolactate synthase inhibitors (ALS). It was conducted two experiments in a greenhouse in a completely randomized design with four replications. Colby’s methodology was used for experiment 1, through the application of quinclorac isolated and in mixture with herbicides imazethapyr, imazapyr e imazapic. The experiment 2, using dose–response curves, tested the herbicides quinclorac isolated and in diferent mixtures with the herbicide imazethapyr. For experiment 1, the expected and observed averages were compared. For experiment 2, the results were analyzed using the sigmoidal logistic model. Additive is the main interaction of mixtures of quinclorac with diferent herbicides from the chemical group of imidazolinones to control resistant C. iria. Mixing with imazethapyr at diferent proportions can cause an additive efect with quinclorac at higher doses.

Effects of light-emitting diodes on protoplast regeneration from gametophytic cells of the commercial kelp Undaria pinnatifida (Laminariales, Phaeophyceae)

Avila-Peltroche, Jose,Won, Boo Yeon,Cho, Tae Oh The Korean Society of Phycology 2022 ALGAE Vol.37 No.2

Light-emitting-diodes (LEDs) are a lighting source useful for the precise evaluation of light quality effect on biological systems. Despite the importance of light spectra on the regeneration of land plant protoplasts ("naked cells"), this factor has not been tested yet on protoplasts from multicellular algae. This study reports on the effects of pure primary colors (red, blue, and green), dichromatic (red plus blue, RB, 1 : 2) and white LEDs on protoplast regeneration from male and female Undaria pinnatifida gametophytes. We also evaluated the effect of different light spectra on pigment composition (chlorophyll a, chlorophyll c, and fucoxanthine), and the light intensities under the best condition on the regeneration process. In the early stages, blue or RB LEDs increased the percentage of dividing female protoplasts, whereas red, blue, and RB LEDs enhanced that of dividing male protoplasts. In the later stages, RB LEDs showed a positive effect only on the percentage of multiple rhizoid-like protrusions (male gametophyte). They also increased the final area of both regenerated gametophytes. The LEDs did not affect pigment composition in female gametophytes. In male gametophytes, in contrast, they reduced chlorophyll c, while blue, RB, and green LEDs decreased fucoxanthin. Under RB LEDs, the optimal light intensity was 80 µmol photons m^-2 s^-1 for female gametophytes and 40 to 60 µmol photons m^-2 s^-1 for male gametophytes. Our results suggest that dichromatic LED illumination (red-blue) improves regeneration of U. pinnatifida gametophyte-isolated protoplasts. Thus, dichromatic LEDs might a suitable light source for enhancing protoplast regeneration in brown seaweeds.

Spanish, English, Minority Languages & mass media

( Raul Avila ) 한국스페인어문학회 2005 스페인어문학 Vol.0 No.37

Digital Marketing of Cotton to Generation Y College Students

Brenda Avila,Jay-Sang Ryu 한국유통과학회 2015 유통과학연구 Vol.13 No.7

Purpose – Gen Y college students have emerged as a profitable consumer segment because of their growing purchasing power and influence on others’ buying decisions. Digital marketing is deemed effective in increasing Gen Y college students’ knowledge of and interest in products and services. This research examined the effect of digital marketing on Gen Y college students’perceptions, attitudes and purchase intentions toward cotton clothing compared to that of conventional print marketing and no marketing. Research design, Date and Methodology -Data were collected from three different groups of college students from a large university in the U.S.: the group with no cotton marketing, those with print media marketing, and those with digital marketing. Result - The findings confirmed that college students who were exposed to cotton digital marketing displayed the highest level of agreement on the benefits of cotton clothing. They also exhibited the most favorable attitudes and strongest purchase intentions toward cotton clothing. Conclusions – To target Gen Y consumers effectively, marketers should consider a digital marketing strategy to promote their products and services.

Corporate Social Responsibility Impact on Business Performance through Green Supply Chain Management: Evidence from Guatemala

Rubén Avila García,박병주,장병윤 한국인터넷방송통신학회 2019 International Journal of Internet, Broadcasting an Vol.11 No.4

The purpose of this research is to examine the relationship between corporate social responsibility (CSR), green supply chain management (GSCM) practices, and business performances. After reviewing the extensive literature, we developed a research model including five constructs: CSR, GSCM practices, environmental, economic and operational performances. We conducted the statistical analyses based on the primary data collected from a survey questionnaire, responded by 93 different company managers in the Republic of Guatemala. Furthermore, we utilized structural equation modeling to analyze the data and to test the hypotheses. The results of the analyses showed that there is a significant influence of CSR on the adoption of GSCM practices. It was also found that GSCM practices have a significant influence on environmental, economic and operational performances. In addition, environmental performance has a significant impact on economic and operational performance. Finally, GSCM has a mediating role on the relationship between CSR and environmental and economic performance, but not with operational performance.

Electronic structure and chemical imaging of smart low dimensional materials

Jose AVILA,Chaoyu CHEN,Stephane LORCY,Maria ASENSIO 한국진공학회 2016 한국진공학회 학술발표회초록집 Vol.2016 No.8

A new record of Feldmannia chitonicola from Korea based on laboratory culture and molecular data

Jose Avila-Peltroche,Antony Otinga Oteng'o,정소영,원부연,조태오 한국환경생물학회 2019 환경생물 : 환경생물학회지 Vol.37 No.3

Feldmannia chitonicola is reported as a new record from Korea based on morphological studies in laboratory-cultured materials and molecular analyses. F. chitonicola is mainly characterized by a small size (1-2 mm), erect filaments mostly unbranched, plurilocular sporangia produced on both prostrate and laterally on the basal part of erect filaments, and 2 types (lanceolate and ovate) of sporangia. In our cultures, sporangia production was slower at 10°C than in 16°C and 20°C. Our molecular analyses of rbcL and cox1 genes supported its independence from other congeners reported for Korea. This is the first report of F. chitonicola for western Pacific.