ABSTRACT The growth in the number of launches of artificial satellites for the most different functions has motivated studies related to control, propagation, and orbit and attitude determination activities. In this paper a study of the Solar Radiation Pressure Torque (SRPT) and Aerodynamic Torque (AT) of the CBERS (China-Brazil Earth Resources Satellite) satellite is done when the models used in the satellite mission are considered. The results showed that for satellites in Low Earth Orbit (LEO), as in the case of CBERS, the AT has more relevant effects on the satellite’s superfıcie than the SRPT. These results could be useful for satellite supervision and control in post-launch, and are vital for attitude and orbit control of the CBERS satellite.

RESUMO O crescimento do número de lançamentos de satélites artificiais para as mais diferentes funções tem motivado estudos relacionados a atividades de controle, propagação e determinação de órbita e atitude. Neste trabalho é feito um estudo do Torque de Pressão de Radiação Solar (TPRS) e do Torque Aerodinâmico (TA) do satélite CBERS (China-Brazil Earth Resources Satellite) quando são considerados os modelos utilizados na missão do satélite. Os resultados mostraram que para satélites em órbitas baixas terrestres (Low Earth Orbit-LEO), como no caso do CBERS, o TA tem efeitos mais relevantes na superfície do satélite do que o TPRS. Estes resultados poderão ser úteis para a supervisão e controle do satélite no pós-lançamento, sendo vital para o controle de atitude e da órbita do satélite CBERS.

Resumen Desde hace algunas décadas, investigadores de varios países se han dedicado a la búsqueda de materiales aglomerados basados en partículas desechadas de la actividad agroindustrial. El objetivo de este trabajo consistió en obtener material aglomerado utilizando cascarillas de arroz y adhesivo comercial poliuretánico de bajo costo, Rubinate 9040 de Huntsman®. Las variables estudiadas en cuatro formulaciones (A, B, C, D) fueron: porcentaje de absorción de humedad, capacidad de hinchamiento, punto de ignición y resistencia a la flexión. Se obtuvieron aglomerados de media y baja densidad. Presentaron valores de absorción de humedad entre 3,5 % - 8,9 % contra 58,5 % - 73 % del testigo comercial utilizado TAC (medidos a 25 y 40 ºC); y capacidad de hinchamiento entre 1 % - 5 % frente al 18 % correspondiente al testigo. Las muestras estudiadas también mostraron punto ignifugo superior al aglomerado testigo. Respecto a la resistencia a la flexión, presentaron valores inferiores al testigo comercial. La formulación más destacada fue B, con valor de 12,22 MPa, frente a 14,72 MPa del aglomerado testigo. Los aglomerados desarrollados son aptos para la construcción en seco donde no se demanden altos esfuerzos de resistencia, soportan bien el sistema de aserrado tradicional, no generan defectos de borde al ser moldurados, y tienen resistencia a la humedad y al fuego.

Abstract Wood-like agglomerates based on agro-industrial waste particles have been studied for decades. The aim of this work is to obtain such kind of materials using rice husks and a low cost commercial polymeric adhesive (polyurethane, Rubinate 9040 from Huntsman®). To carry out the study, medium and low-density agglomerates were obtained. Four samples with different formulations (A, B, C, and D) were made and the following were the parameters studied: percentage of moisture absorption, swelling capacity, ignition point, and flexural strength. The humidity absorption values of the samples varied between 3.5 - 8.9 %, while that of the commercial sample used as control did between 58.5 - 73 % (measured at room temperature, and 40°C). The swelling capacity values of the samples varied between 1 - 5% versus 18% for the commercial control sample. The studied samples also showed ignition point higher than that of the control agglomerate sample. The values of flexural strength of the studied samples were lower than that of the control sample. The sample showing the best mechanical properties was formulation "B" with a flexural strength value of 12.22 MPa (the value of flexural strength for the control sample was 14.72 MPa). The wood-like agglomerates obtained show properties that make them eligible as dry-building materials when high mechanical resistance is not required. However, the samples obtained resist well the cutting mechanical stress of a traditional sawmill, do not generate rough edges when molded, and are moisture- and fire-resistant.

ABSTRACT The edge effect makes forest communities more susceptible to changes and may cause changes in different ecosystem characteristics such as litter production. The objective of this work was to evaluate the edge effect on the contribution of litter and its temporal variation in a Semi-Deciduous Seasonal Forest fragment located in Vitória da Conquista, BA, Brazil. Four sampling ranges were delimited in the forest fragment: edge (0-10 m from the edge), transition 1 (40-50 m from the edge), transition 2 (80-90 m from the edge) and interior (400-410 m from the edge). The produced litter was collected monthly. The main litter components were leaves and branches in all sampling ranges. The contribution of the other fractions obeyed different orders at the edges (bark > reproductive structures) and interior (reproductive structures > bark). The edge effect did not influence the contribution of total litter and its temporal variation, only manifesting in the production of reproductive structures.

Abstract In this paper, an adaptive low density parity check (LDPC). encoder for complete Free Space Optics/Continuous Variable-Quantum Key Distribution (FSO/CV-QKD) system using a Commercially available Off-The-Shelf (COTS) device for emulated dynamical atmospheric turbulence levels is presented. The experimental and emulation results show the maximum and minimal final secret key rates of ≈ 105 Kbps and ≈ 10 Kbps, respectively, for minimal and maximal throughput in a commercial network, 30 Mbps and 90 Mbps, respectively. Our proposal presents an adequate performance for weak and moderate atmospheric turbulence levels and a suitable option for improving the use of Quantum Key Distribution (QKD) systems.

Abstract In this paper, a dynamical and adaptive LDPC coding scheme is proposed in order to improve the performance of the cryptographic key distillation protocol of an FSO/CV-QKD system considering the atmospheric turbulence levels that may be present in the classic channel. In this scheme, the Generator and Parity-check matrices of the encoder are modified according to the Rytov variance values estimated in the classical channel in order to improve the final secret key rate of the QKD system. The simulation results show that the final secret key was incremented 87.5 Kbps (from 52.5 Kbps to 140 Kbps) using the adaptive code rate; meaning that the information encrypted and transmitted is increased. In addition, the use of the dynamical encoder avoids the drastically reduction of the final secret key rate when the conditions of the classical channel are considered. Our proposal might be implemented based on the use of high-speed FPGA’s and DSP’s commercially available.

Esse trabalho descreve um experimento simples e de fácil execução, destinado ao estudo da transferência de calor e massa por meio de uma aula prática. Tal estudo é realizado a partir da fusão de uma placa de gelo, ao ar ambiente, e com base na avaliação quantitativa do calor transferido por radiação, convecção e condensação de vapor d'água sobre a superfície dessa placa. Os valores teóricos, previstos a partir de equações relativas a esses processos de transferência de calor e massa, são comparados com dados experimentais relativos à taxa mássica de fusão dessa placa. A facilidade na execução dos ensaios e a simplicidade do equipamento empregado torna esse experimento uma atividade prática de fácil implementação em disciplinas que tratam da transferência de calor e massa. Além disso, a concordância entre valores teórico e experimental da taxa de transferência de calor e massa, e a metodologia empregada na análise e quantificação dessa taxa, viabilizam o experimento proposto como uma ferramenta pedagógica eficiente para o estudo desse tema.

This work describes a simple and easy-to-perform experiment, destined to the study of the heat and mass transfer by means of a practical class. This study is carried out from the melting of an ice sheet into ambient air and based on the quantitative evaluation of the heat transferred by radiation, convection and condensation of water vapor on the surface of that plate. The theoretical values, predicted from equations related to these processes of heat and mass transfers, are compared with experimental data concerning the melting mass rate of this plate. The ease of running the tests and the simplicity of the equipment employed makes this experiment a practical activity that is easy to implement in disciplines dealing with heat and mass transfer. In addition, the agreement between theoretical and experimental values of the heat and mass transfer rate, and the methodology used in the analysis and quantification of this rate, make feasible the proposed experiment as an efficient pedagogical tool to study this subject.

Nesse trabalho é descrito um experimento quantitativo destinado a avaliar a transferência de calor durante o resfriamento de um cilindro de aço e comparar os resultados experimentais com valores previstos em modelos de convecção e radiação do calor. Além de executar os ensaios, o aluno é requisitado a confeccionar uma planilha eletrônica que detalha os cálculos realizados e avalia a consistência dos resultados. O experimento foi concebido para ser facilmente implementado em aulas práticas de cursos de graduação; e, nesse intuito, buscou-se utilizar materiais e equipamentos que viabilizem a realização de ensaios simples e de fácil execução. Os resultados obtidos são satisfatórios e propiciam uma análise quantitativa sobre os mecanismos envolvidos na transferência de calor num sistema físico real.

This work describes a quantitative experiment to evaluate the heat transfer during the cooling of a steel cylinder and compare the experimental results with predicted values in convection and heat radiation models. In addition to performing the tests, the student is required to prepare a spreadsheet that details the calculations performed and evaluates the consistency of the results. The experiment was designed to be easily implemented in experimental classes of undergraduate courses; and, for this, we tried to use materials and equipment that make feasible the realization of simple and easy execution tests. The results obtained are satisfactory and provide a quantitative analysis on heat transfer mechanisms involved in a real physical system.

RESUMO O processo de decomposição regula o acúmulo de serapilheira e a ciclagem de nutrientes em ecossistemas florestais, sendo fundamental para sua manutenção. O objetivo deste trabalho foi avaliar a dinâmica de decomposição foliar em uma Floresta Estacional Semidecidual Montana e em plantios homogêneos de Pterogyne nitens Tul. e de Eucalyptus urophylla S. T. Blake, localizados no município de Vitória da Conquista, Bahia, Brasil. Para avaliação da decomposição, folhas recém-caídas foram coletadas, secas em estufa a 65oC, pesadas e colocadas em litter bags, que foram distribuídos aleatoriamente na superfície do piso florestal de cada uma das áreas estudadas. Realizaram-se coletas de cinco litter bags de forma aleatória após 30, 60, 90, 120, 150 e 180 dias da instalação. Com base nas massas obtidas, foram estimados o percentual de massa remanescente, as taxas de decomposição (k) e o tempo de meia-vida do folhedo (t1/2 ). Para caracterização química, foram separadas três subamostras do material foliar seco, que foram moídas e analisadas, determinando-se os teores de nitrogênio total, carbono, polifenóis, lignina e celulose. Os dados de decomposição foram relacionados com variáveis ambientais (precipitação, temperatura e umidade do ar) e microambientais (temperatura e umidade do solo) referentes ao mês de coleta. O acúmulo total de serapilheira variou entre as áreas estudadas, o maior valor foi observado no plantio de Eucalyptus urophylla (12,7 Mg ha-1), seguido pela floresta nativa (6,9 Mg ha-1) e plantio de Pterogyne nitens (1,1 Mg ha-1). Ao final dos seis meses de avaliação, o Eucalyptus urophylla apresentou a maior massa remanescente (73,6%), seguido da floresta nativa (67,8%) e Pterogyne nitens (46,3%). A constante de decomposição (k) foi maior para a Pterogyne nitens (0,0054 g g-1dia), com menores valores para floresta nativa (0,0016 g g-1dia) e Eucalyptus urophylla (0,0015 g g-1dia). A taxa de decomposição da serapilheira foliar do povoamento de Pterogyne nitens situa-se em uma posição superior em relação às taxas da floresta nativa e do povoamento de Eucalyptus urophylla, o que proporciona à espécie maior capacidade de reciclar matéria orgânica e nutrientes. O processo de decomposição nos ecossistemas estudados foi influenciado não apenas pela qualidade do folhedo, mas também pela qualidade do seu microambiente.

ABSTRACT The decomposition process regulates the accumulation of litter and nutrient cycling in forest ecosystems, being central to its maintenance. The objective of this study was to evaluate the dynamics of leaf litter decomposition in three forest ecosystems (semideciduous forest Montana and homogeneous stands of Pterogyne nitens Tul. and Eucalyptus urophylla ST Blake), located in Vitória da Conquista, Bahia, Brazil. To evaluate the decomposition, newly fallen leaves on the ground of trees and shrubs in each of the studied toppings were collected. The sheets were dried at 65 °C, and thereafter, 10 g portions were weighed and placed in litter bags, which were randomly distributed on the surface of the forest floor in each of the areas studied. Five litter bags at random were collected after 30, 60, 90, 120, 150 and 180 days of installation. After collection, the material contained in each litter bag was subjected to drying in an oven at 65 °C and weighed. Based on the obtained masses were estimated the percentage of the remaining mass, the rate of decomposition (k) and half-life time of the litter (t1/2 ). For chemical characterization three subsamples were separated from the dried leaf litter, which were ground and analyzed by determination of the total nitrogen, carbon, polyphenols, lignin and cellulose. The decomposition was related to environmental variables (precipitation, temperature and humidity) and the microenvironment (temperature and soil moisture).The total accumulated litter varied significantly between the settlements studied, the highest value was observed in the area of Eucalyptus urophylla (12,7 Mg ha-1), followed by native forest (6,9 Mg ha-1) and Pterogyne nitens (1,1 Mg ha-1). At the end of the six months of the experiment, Eucalyptus urophylla showed the greatest remaining mass (73,6%), followed by native forest (67,8%) and Pterogyne nitens (46,3%). The decomposition constant (k) was higher in litter of Pterogyne nitens (0,0054 g g-1 day), with lower values for native forest (0,0016 g g-1 day) and Eucalyptus urophylla (0,0015 g g-1day). The rate of decomposition of leaf litter of the peopling of Pterogyne nitens is in a superior position in relation to rates of native forest and stand of Eucalyptus urophylla, which provides the largest species ability to recycle organic matter and nutrients. The decomposition process in the studied ecosystems is influenced not only by the quality of the litter but also by the quality of their microenvironment.

We are currently in the process of calibration of a new cosmic ray detector called SciBar Cosmic Ray Telescope (SciCRT) located at the top of the Sierra Negra volcano at 4,600 m.a.s.l., in Eastern Mexico. The SciCRT will work mainly as a Solar Neutron and Muon Telescope, with a high angular resolution (~ 1°), but it will also serve as a gamma ray and hadron shower detector. The mini-SciCR is a prototype of the SciCRT, it uses the same scintillator bars and recording hardware, the size of the mini-SciCR is 1/1568 compared with the SciCRT. In this paper we will report the main results obtained with the mini-SciCR that was operating at the top of the Sierra Negra volcano from October 2010 to July 2012. Our main aims were to show the appropriate performance of all the detector systems and to develop a tecnique to separate the flux of soft and hard secondary cosmic rays with the help of a Monte Carlo simulation, our energy range of interest is from 100 MeV to a few GeV. Aditionally we will report results with a modification of the detector setup that helped to confirm the correct identification of the particle species.

O experimento foi desenvolvido para avaliar os efeitos da inclusão de níveis de farelo de mamona destoxificado sobre a composição químico-bromatológica, as características fermentativas e as perdas de matéria seca da silagem de cana-de-açúcar. Os tratamentos consistiam em quatro níveis (0, 7, 14 e 21% da matéria natural) de inclusão do farelo de mamona. O delineamento foi inteiramente ao acaso, com cinco repetições. Foram usados silos de PVC, com 50cm de altura e 10cm de diâmetro, para a produção das silagens, que foram abertos após 60 dias. A densidade de forragem nos silos foi correspondente a 750kg de matéria natural/m3. Os silos foram pesados no início e ao final do período experimental para quantificar as perdas por gases e efluentes. A inclusão de farelo de mamona elevou os teores de MS e proteína bruta e reduziu os teores de fibra em detergente neutro, N-NH3, etanol e as perdas por gases e efluentes das silagens, não ocasionando efeito nos valores de pH. A fermentação alcoólica durante a ensilagem foi controlada com a inclusão do aditivo.

This experiment was designed to evaluate the effects of the inclusion of detoxified castor bean meal (CM) content on the chemical-bromatological composition, as well as the fermentation characteristics and dry matter losses of sugarcane silage. The treatments consisted of four levels (0, 7, 14 and 21% natural matter) of addition of castor bean meal. The design was completely randomized, with five replicates. The material was ensiled in PVC silos of 50-cm in height and 10-cm in diameter, which were opened after 60 days. The density of fodder maintained in the silos was equal to 750kg of natural matter/m3. In order to quantify the gas and effluent losses, the silos were weighed at the beginning and at the end of the experiment. The addition of castor bean meal has increased the levels of DM and crude protein and reduced the levels of neutral detergent fiber, N-NH3, ethanol, and gas and effluent losses from silages, but did not affect pH values. During ensiling, alcoholic fermentation was controlled with the inclusion of the additive.

Estudiamos la dieta de 15 especies de ranas montanas del género Pristimantis (Craugastoridae) en la Cordillera Occidental de Colombia para determinar su variación, amplitud y traslape de nicho. En los contenidos estomacales e intestinales de 154 especímenes se identificaron 499 presas que fueron organizadas en 74 categorías diferentes. Las 15 categorías de presas más comunes representaron el 65 % de la dieta. Las familias de invertebrados Isotomidae, Chironomidae, Formicidae y Tipulidae fueron las más abundantes, representando el 32 % de la dieta de las ranas. Diez de las 15 especies de ranas presentaron al menos un ítem de Araneae. Coleoptera y Tipulidae fueron otras categorías frecuentemente encontradas en los tractos digestivos de las ranas (nueve especies de ranas presentaron estos ítems), seguidas de Acari y Carabidae (ocho especies). En general, los escarabajos fueron encontrados en los tractos gastrointestinales de todas las especies, excepto en P. quantus, pero este resultado debe tratarse con precaución porque solo un individuo de esta especie fue capturado. Pristimantis hectus mostró una dieta especializada consumiendo principalmente dípteros de la familia Chironomidae, mientras que las especies restantes mostraron una dieta generalista. Pristimantis palmeri presentó superposiciones de nicho con P. erythropleura (Фjk = 0,69), P. myops (Фjk = 0,64), y P. orpacobates (Фjk = 0,64). Nuestros resultados sugieren que la mayoría de las especies estudiadas son generalistas que se alimentan de manera oportunista de dípteros, arácnidos, colémbolos, coleópteros e himenópteros. Aquí, reportamos la dieta de especies montanas de Pristimantis y discutimos los resultados con datos de otros estudios en especies relacionadas de regiones montanas y tierras bajas.

We studied the diet of 15 montane frog species of the genus Pristimantis (Craugastoridae) from the Andes of Western Colombia to determine the diet range, breadth of niche and overlap among species. We identified 499 prey items from stomach and intestinal contents of 154 specimens. Prey items were included in 74 different categories. The most common 15 prey categories accounted for 65 % of all frogs' diet. The invertebrate families Isotomidae, Chironomidae, Formicidae, and Tipulidae were the most abundant categories and accounted for 32 % of the frogs' diet. Ten of the 15 frog species were found with at least one item of Araneae. Coleoptera and Tipulidae were found in nine frog species, and Acari and Carabidae in eight frog species. In general, beetles were found in gastrointestinal tracts of all species examined, except for P. quantus, but interpretation needs caution because only one individual of this species was caught. Pristimantis hectus showed a specialized diet, consuming mainly dipterans of the family Chironomidae, while the remaining species showed a generalist diet. Pristimantis palmeri showed niche overlap with P. erythropleura (Фjk = 0.69), P. myops (Фjk = 0.64), and P. orpacobates (Фjk = 0.64). Our results suggest that most of the frogs species studied are generalist, foraging opportunistically on dipterans, arachnids, collembolans, coleopterans, and hymenopterans. Here, we report the diet of montane Pristimantis species and discuss the results in comparison with data on related species in montane and lowland regions.

The statistics of temporal integration of dynamically scattered light is commonly employed to calculate the correlation time of the light and related physical properties of the object that produce it, i.e. scatterer's speed. Recently, studying the statistics of time-averaged fluorescence intensity, it was reported that a small dead-time (1% of the exposure time) of the photo-detector increases the correlation time by one order of magnitude compared with an ideal photo-detector. Applying the same theory to the speckle contrast calculation for blood flow measurement, we found that the effect of dead-time is negligible compared to an ideal photo-detector for contrast calculation.

This study was conducted to determine the effect of the air temperature variation on the mean surface temperature (MST) of 7- to 35-day-old broiler chickens using infrared thermometry to estimate MST, and to study surface temperature variation of the wings, head, legs, back and comb as affected by air temperature and broiler age. One hundred Cobb® broilers were used in the experiment. Starting on day 7, 10 birds were weekly selected at random, housed in an environmental chamber and reared under three distinct temperatures (18, 25 and 32 ºC) to record their thermal profile using an infrared thermal camera. The recorded images were processed to estimate MST by selecting the whole area of the bird within the picture and comparing it with the values obtained using selected equations in literature, and to record the surface temperatures of the body parts. The MST estimated by infrared images were not statistically different (p > 0.05) from the values obtained by the equations. MST values significantly increased (p < 0.05) when the air temperature increased, but were not affected by bird age. However, age influenced the difference between MST and air temperature, which was highest on day 14. The technique of infrared thermal image analysis was useful to estimate the mean surface temperature of broiler chickens.

Foram avaliadas as populações microbianas, o pH, a relação nitrogênio amoniacal/nitrogênio total (N-NH3), as concentrações de ácidos láctico, acético e butírico e a composição bromatológica de silagens de Brachiaria decumbens cv. Basiliski de cinco idades de rebrotação (30, 40, 50, 60 e 70 dias) utilizando-se silos laboratoriais de 2 kg de capacidade. Utilizou-se um esquema fatorial 5 × 6 (5 idades de rebrotação × 6 períodos de fermentação), em um delineamento inteiramente casualizado, com três repetições. Os períodos de fermentação foram 1, 3, 7, 14, 28 e 56 dias. Na forragem fresca, foram registradas populações de bactérias do ácido láctico variando entre 3,93 (30 dias de rebrotação) e 5,51 (70 dias de rebrotação) log unidades formadoras de colônia (ufc)/g de forragem. Nas silagens, foram registradas populações máximas desses microrganismos no sétimo dia de fermentação (8,69 log ufc/g de silagem). As populações de enterobactérias persistiram até o 28º dia, com os valores máximos observados logo no primeiro dia de fermentação (7,89 log ufc/g de silagem). Os teores de MS, FDN, FDA e NIDA aumentaram linearmente, enquanto os de PB diminuíram linearmente com a idade de rebrotação das plantas. Houve redução linear dos teores de MS, PB e FDN e aumento linear dos teores de NIDA com o avanço do período fermentativo. O teor de N-NH3 decresceu e aumentou linearmente com a idade de rebrotação e com o período de fermentação, respectivamente. O pH decresceu exponencialmente com o período de fermentação. Os teores de ácido láctico aumentaram e os de ácido butírico decresceram linearmente com a idade de rebrotação. A espécie de Lactobacillus predominante em plantas de capim-braquiária é o Lactobacillus plantarum.

Microbial populations, pH, ammonium nitrogen/total nitrogen (N-NH3) ratio, concentrations of lactic acid, acetic acid and butyric acid and the chemical composition of Brachiaria decumbens cv. Basiliski silages at different regrowth ages (30, 40, 50, 60 and 70 days) were evaluated by using 2-kg capacity laboratory silos. It was used a 5 × 6 factorial scheme (5 regrowth ages × 6 fermentation periods) in a complete random design, with three replicates. The fermentation periods were 1, 3, 7, 14, 28 and 56 days. Lactic acid bacteria populations were recorded in fresh forage varying from 3.93 (30 days of regrowth) to 5.51 (70 days of regrowth) log colony-forming units (cfu)/g forage. Maximum populations of these microorganisms were recorded in the silages on the seventh day of fermentation (8.69 log cfu/g silage). Enterobacteria populations persisted until the 28th day, with maximum values found as early as the first day of fermentation (7.89 log cfu/g silage). Levels of DM, NDF, ADF and ADIN increased linearly whereas values of CP decreased linearly with age of regrowth of the plants. There was a linear reduction in the levels of DM, CP and NDF and linear increase in the levels of ADIN over the period of fermentation. N-NH3 level decreased and increased linearly with regrowth age and fermentation period, respectively. The pH decreased exponentially with fermentation period. Lactic acid increased and butyric acid decreased linearly with regrowth age. The predominant Lactobacillus plantarum species in signalgrass plants is Lactobacillus plantarum.