Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

This work describes the optical and electrical characterization of an integrated optoelectronic receiver. The receiver iscomposed of a photodiode and a transimpedance amplifier, both fabricated in silicon technology using a 0.8 μmBiCMOS process. The total area occupied by the photodiode is of 10,000 μm2. In a first step, the generatedphotocurrent of the photodiode is measured for the wavelengths of 780 nm and 830 nm at different levels of opticalpower. In a second step, the responsivity and quantum efficiency parameters of the photodiode are computed. Finally,an electrical measurement including the transimpedance amplifier is achieved. A potential application for thisoptoelectronic receiver is on the first optical communications window.

In this paper we deal with the experimental synchronization of the Colpitts oscillator in a real-time implementation. Ourapproach is based on observer design theory in a master-slave configuration thus, a chaos synchronization problemcan be posed as an observer design procedure, where the coupling signal is viewed as a measurable output and aslave system is regarded as an observer. A polynomial observer is used for synchronizing the Colpitts oscillatoremploying linear matrix inequalities. Finally, a comparison with a reduced order observer and a high gain observer isgiven to assess the performance of the proposed observer.

Retailing plays an important part in modern economic development, and supply chain coordination is the researchfocus in retail operations management. This paper reviews the collaborative forecasting process within the frameworkof the collaborative planning, forecasting and replenishment of retail supply chain. A Bayesian combination forecastingmodel is proposed to integrate multiple forecasting resources and coordinate forecasting processes among partners inthe retail supply chain. Based on simulation results for retail sales, the effectiveness of this combination forecastingmodel is demonstrated for coordinating the collaborative forecasting processes, resulting in an improvement ofdemand forecasting accuracy in the retail supply chain.

This paper proposes a combinatorial evaluation method for the effectiveness of supplies assessed on the basis ofoptimal route connections between warehouses and receivers (customers) with usage of rough sets theory inmultidimensional approach. Effectiveness is evaluated as the difference between the value of orders and theirimplementation costs resulting from transportation. The uncertainty concerns the assortment and the level of orders.Among various order alternatives using the proposed methodology one can observe the most and least effectiveconfiguration. One can use it to support trade policy, create service areas adapting them to the location structure ofsupply, and receive nodes.

A prefeasibility study of a solar power plant project was carried out in order to study and search the best location toinstall a concentrated solar power plant according to a tender with the Algerian electricity company “SPE” following aspecific criteria and methodology in order to obtain a site with a maximum possible irradiation along with othereconomic constraints. Normally, eleven years of solar irradiation data from an on-ground weather station is needed forsite assessment, such data are not available, hence the typical meteorological year irradiation based on satelliteimagery results is needed in order to have the accurate value, therefore we can give the right evaluation for the sitecandidate. Additionally, an analysis of a weather measurement station was carried out to ensure the properfunctioning of the weather data reception and analysis processes, and thus to optimize the algorithm of a data loggerin order to get the right measurement with a minimum error. The correction algorithm was developed by weatherscientists and was added to the data logger main program.

There is a general interest in the study of schemes for the measurement of the efficiency of universities, whichgenerates demand but at the same time is controversial because of the complexity of the problem. This problem isassociated with the highly combinatorial characteristics that occur when facing the selection of the proper combinationof the attributes, namely inputs and outputs. This investigation proposes an approach to measure the institutionalefficiency in higher educational institutions combining Analytic Hierarchy Process (AHP) with Data EnvelopmentAnalysis (DEA). Both methods are frequently used independently, on a global level in areas such as government,business, industry, health care and education. The use of the two methodologies as an evaluation tool is novel andvery useful in institutional efficiency studies where results already exist, in order to obtain and confirm importantequivalences. The use of the proposed approach is demonstrated using the Queretaro State University - UniversidadAutónoma de Querétaro (UAQ) - as a case study.

Contemporary patterns of plant biodiversity result from the ecological and evolutionary processes generated by species interactions. Understanding these interactions is key for effective biodiversity conservation at the species and the ecosystem level. Orchid species often have highly specialised pollinator interactions, and the preservation of these is critical for in situ orchid conservation. The majority of orchid species occur in tropical regions, and information regarding their interactions is limited. We present data on pollinator identities, pollination mechanisms and flowering phenology of the Colombian endemic orchid, Pleurothallis marthae. We evaluated the mechanisms of attraction, the presence of osmophores, and the reproductive system of the species. Pleurothallis marthae is self-compatible with nocturnal anthesis pollinated by Mycetophila sp. (Mycetophilidae), probably attracted by a string fungus like smell liberated by the flower and Bradysia sp. (Sciaridae) that feed on nectar in the labellum. Osmophores and nectaries were detected in the epidermis of the sepals and petals. We present new evidence that the genus Pleurothallis is adapted to Diptera pollination. Our study indicates that the pollination mechanism of P. marthae is based on the nocturnal attraction of two species of fungus gnats, probably combining food attraction and brood place deception

We determined the population structure and some habitat conditions of a Ionopsis utricularioides (Orchidaceae) population in an orange orchard (citrus sinensis, Rutaceae), located in the “La Juanita” farm, Pinar del Río, Cuba. We took into account all the orange trees of the orchard, and located all the individuals of I. utricularioides. The following variables were analyzed: height and diameter of branches in growing orchids, orchid distribution on phorophytes (trunk, branches or twigs), life stage of the orchids (immature or adults), orientation of orchids in the phorophyte, if the plants were solitary or aggregated, and kind of neighbours in the case of the aggregate. Of the 10 trees of c. sinensis, eight trees had orchids of I. utricularioides, with 217 plants. Almost all orchids were observed on the twigs (98.61 %) and none were observed on the trunk of the tree. The number of plants is relatively high in the two stage of life. Most plants of I. utricularioides were found growing aggregate with individuals of the same species, or with other species of vascular epiphytes. This is a stable and mature population. Growing up in aggregation can give competitive advantages to I. utricularioides.

As a result of Hon Ba nature reserve survey, Hetaeria finlaysoniana, previously recorded from Thailand, Myanmar and southern China, is newly recorded from Vietnam. Description of studied plants is presented together with notes on ecology and photographic documentation. These plants were collected in southern Vietnam (Hon Ba Nature Reserve, Khanh Hoa), which is located quite far from other known localities and thus a larger distribution of this possibly overlooked species could be expected. Additionally, H. youngsayei is newly recorded from the same reserve, 540 km from the nearest previously known locality. Distribution of both species is discussed and an updated identification key for all Vietnamese members of the genus Hetaeria is presented.

Malaxis nana C. Schweinf. is known from two herbarium specimens collected in 1925 in San Ramón, Alajuela province, and three additional specimens without detailed locality data collected in the late 1800’s, all of them in Costa Rica. This species had not been registered since. Malaxis nana is hereby first reported for Las Cruces Biological Station, Puntarenas province, in southern Costa Rica. An updated description, illustration, photographs and distribution map for this taxon are provided.