bluuebunny/crossref_metadata_2025 huggingface dataset:
MOCVD Growth of AlN/GaN DBR Structure Under Various Ambient Conditions
Authors: Yao H. H. , Lin C. F. , Wang S. C.
Published: June 2019

High reflectivity AlN/GaN DBR structures were grown by MOCVD under three ambient gas conditions during the AlN layer growth. Highest peak reflectivity of about 94.5% with a stopband width of 18 nm at a center wavelength of 442nm was obtained under pure N2 gas ambient growth condition. The center wavelength of the DBR structures blue-shifted to 418 nm and 371 nm and the peak reflectivity also showed a reduction to 92 % and 79 % under the ambient gas conditions of a N2/H2 mixture and pure H2 respectively. Surface roughness showed slight increase from 8nm to 12nm, and the groove depth shows an increase from 25nm to 60nm with increasing the H2 ambient gas ratio. TEM results showed that AlN grown rate was reduction with the increasing H2 content in the ambient gas. The simulation result indicated that optical loss of AlN layers was increased from 450 cm-1 to 1850 cm-1 with the increasing H2 content in the ambient gas.
Low Ohmic Contact Resistance of GaN by Employing XeCl Excimer Laser
Authors: Lee Seung-Chul , Her Jin-Cherl , Han Sang-Myun , Seo Kwang-Seok , Han Min-Koo
Published: June 2019

We have investigated a new method by which selective high doping concentration of GaN can be obtained using XeCl excimer laser and presented low ohmic contact resistance fabricated by the proposed method. We have irradiated silicon film deposited by sputtering on GaN using XeCl excimer laser and formed ohmic contact on the region irradiated by laser. Ohmic contact resistance by laser doping process was effectively reduced to 0.27 ohm-mm while 0.66 ohm-mm was measured in ohmic contact by conventional method. We have verified that silicon is diffused into GaN by high laser energy during laser irradiation through SIMS analysis and ohmic contact resistance is reduced due to increase of doping concentration under ohmic contact region.
Experimental Evaluation of a-Se Flat-Panel X-ray Detector for Digital Radiography
Authors: Choi Jang-Yong , Park Ji-Koon , Lee Dong-Gil , Kang Sang-Sik , Nam Sang-Hee
Published: June 2019

Nowadays, large area, flat panel solid state detectors are being investigated for digital radiography. In this paper, development and evaluation of a selenium-based flat-panel digital xray detector are described. The prototype detector has a pixel pitch of 139μm and a total active imaging area of 7″×8.5″, giving a total of 1.9 million pixel. This detector include a x-ray imaging layer of amorphous selenium as a photoconductor which is evaporated in vacuum state on a TFT flat panel, to make signals in proportion to incident x-ray. The film thickness was about 500μm. To evaluate the imaging performance of the digital radiography (DR) system developed in our group, sensitivity, linearity of the response of exposure, the modulation transfer function(MTF) and detective quantum efficiency(DQE) of detector was measured. The measured sensitivity was 4.16×106 ehp/pixel mR at the bias field of 10 V/μm: The beam condition was 41.9 KeV. Measured MTF at 2.5 lp/mm was 52%, and the DQE at 1.5 lp/mm was 75%.
Analysis of Leakage Currents in AlGaN/GaN Current Aperture Vertical Electron Transistors (CAVETs)
Authors: Ben-Yaacov Ilan , Seck Yee-Kwang , DenBaars Steven P. , Hu Evelyn L. , Mishra Umesh K.
Published: June 2019

A complete analysis of leakage currents in AlGaN/GaN Current Aperture Vertical Electron Transistors (CAVETs) with regrown aperture and source regions was carried out. The total observed leakage current was found to be a combination of both gate leakage and source leakage. Two paths for source leakage have been identified; electrons passing directly through the insulating layer to the drain region as well as electrons traveling through the aperture but underneath the 2DEG at the AlGaN/GaN interface. Source leakage through the insulating layer resulted from pits formed at the onset of regrowth, as the sample was heated to growth temperature, and was successfully eliminated by optimizing regrowth conditions. Source leakage underneath the 2DEG occurred when the unintentionally doped (UID) GaN layer above the insulating layer was not fully depleted and could be eliminated by reducing the thickness of the UID GaN layer. Gate leakage has been attributed to the enhanced incorporation of n-type impurities inside as well as above the aperture region during regrowth, resulting in a narrowing ofthegateSchottkybarrier.
Modulation of Energy Band Gap of ZnO Thin Films Grown by Pulsed Laser Deposition
Authors: Lee Sang Yeol , Li Yuan , Lee Jang-Sik , Lee J. K. , Nastasi M. , Crooker S.A. , Jia Q.X. , Kang Hong-Seong , Kang Joeng-Seok
Published: June 2019

ZnCdO thin films were deposited on (001) sapphire substrates by pulsed laser deposition. Modulation of the energy band gap of ZnCdO was induced by changing the processing parameters. The optical energy band gap of ZnCdO thin films, measured by photoluminescence and transmittance, changed from 3.289 eV to 3.311 eV due to the variation of annealing temperatures. The change of the optical properties was attributed to the change of the stoichiometry of ZnxCd1-xO as illustrated by Rutherford backscattering spectroscopy.
Femtosecond Pulses as a New Photonic Source for Growing Thin Films by Pulsed-laser Deposition
Authors: Millon Eric , Perrière Jacques , Albert Olivier , Etchepare Jean , Boulmer-Leborgne Chantal
Published: June 2019

The femtosecond (fs) lasers display noticeable specificities compared with the nanosecond (ns) ones operating in the UV domain, and classically used for the pulsed-laser deposition (PLD) technique. The ultra-short laser pulses offer the feature of minimal thermal damage induced in the target material, and the very high intensities (1012-14 W/cm2) available with fs lasers are likely to allow the ablation of any kind of materials, even the wide band gap insulators.

The morphology, structure, composition and properties of the films obtained by fs PLD are studied according to the experimental growth conditions, the nature of the target material, and the dynamic expansion of plasma plume. In the case of ZnO, smooth, dense and nanocrystalline films (10 to 30 nm crystallites) can be epitaxially grown on adequate substrates (i.e. sapphire). On the contrary, BaTiO3 films are formed by the random stacking of aggregates (10 to 200 nm) leading to a non negligible surface roughness,. In addition, the chemical composition of fs PLD thin films of multicomponent compound (i.e. BaTiO3) is not homogeneous, an enrichment in the lighter element being observed in the central part of the film. These properties are related to the phenomena taking place during the various steps of the process (laser-matter interaction, plasma formation, expansion) through time resolved emission spectroscopy and plume optical imaging measurements.
Oxidation of Candutm Fuel by the Products of the Alpha Radiolysis of Groundwater
Authors: Sunder S. , Shoesmith D.W. , Johnson L.H. , Wallace G.J. , Bailey M.G. , Snaglewski A.P.
Published: June 2019

The oxidation of CANDUTM fuel by the products of alpha radiolysis of water is being investigated using X-ray Photoelectron Spectroscopy and electrochemical techniques. Possible mechanisms of oxidation of U02by 02 and H202, two of the oxidants formed during radiolysis of water, are discussed. Oxidation by H202depends upon its concentration and the pH of the solution. The oxidation of U02by the products of alpha radiolysis of water, formed by an alpha flux comparable with that expected at the used- fuel surface at the estimated time of waste container failure, caused very little dissolution of UO2fuel. The presence of reductants in groundwater reaching the fuel surface will diminish the fuel oxidation by the radiolysis products.
Experimental study of the Dissolution of spent fuel at 85°C in Natural Ground Water
Authors: Wilson Charles N. , Shaw Henry F.
Published: June 2019

Semi-static dissolution tests using pressurized water reactor spent fuel rod segments and NNWSI reference J-13 well water in sealed stainless steel vessels at 85°C are being conducted in support of the Waste Package Task of the NNWSI Project. Test specimens include: bare fuel plus the empty cladding hulls, fuel rod segments with artificially induced cladding defects and water-tight end caps, and undefected fuel rod segments with water-tight end caps. The test conditions approximate those expected in the proposed NNWSI Project repository when the waste package has cooled sufficiently to allow water to enter a breached container and contact the fuel rods, some of which may exhibit various degrees of cladding failure. Periodic solution samples (unfiltered and filtered) were analyzed for most radionuclides for which cumulative release limits are listed by the U.S. Environmental Protection Agency. Results from the first six-month cycle of the 85° C tests are presented and are compared with results from the first cycle of a previous test series run at 25° in fused silica test vessels.
A Corrosion Model for Nuclear Waste Containers
Authors: Walton John C. , Sagar B.
Published: June 2019

Theory of a mechanistic model for estimating the maximum rate of uniform corrosion for a steel or copper container in a saturated repository environment is described. Four oxidants that are considered are oxygen, sulfate, radiolysis products, and water. Rates of corrosion from oxygen and sulfate reduction are assumed limited by the rate of inward diffusion of the oxidant through the rock, packing, and corrosion product layers surrounding the container. Reduction of water is limited by kinetic processes as influenced by mass transfer of products and reactants, temperature, and pH. Substantial changes in the system resulting from the corrosion process are predicted to occur over time.
Performance Analysis of a Repository for Low and Intermediate Level Reactor Waste
Authors: Vieno Timo , Nordman Henrik , Vuori Seppo , Peltonen Esko
Published: June 2019

In Finland, utilities producing nuclear energy are responsible for the management of the radioactive waste, including final disposal. As regards low and intermediate level waste, the approach has been adopted to employ the power plant sites for locations of repositories. The repositories will be excavated at the depth of about 50 to 125 m in the bedrock of the two Finnish nuclear power plant sites, Loviisa and Olkiluoto.

The performance analysis presented in this paper has been carried out for the Preliminary Safety Analysis Report (PSAR) of the Olkiluoto reposi- tory. A flexible model has been developed to estimate the release of radio- nuclides from waste packages and their subsequent transport through the engi- neered barriers in the repository. Gradual degradation of the engineered barriers is accounted for by altering parameters at fixed time points. Safety margins of the disposal concept have been evaluated by including disturbed evolution scenarios in the analysis.
Zeolitization of Glassy Topopah Spring Tuff Under Hydrothermal Conditions
Authors: Knauss Kevin G.
Published: June 2019

In support of the Nevada Nuclear Waste Storage Investigations Project experiments were conducted to study the effects of heat generated by a nuclear waste repository in densely welded, devitrified tuff on the underlying, compositionally-equivalent glassy tuff at Yucca Mtn. Solid wafers of glassy tuff were reacted with a dilute ground water for several months at 150°C and 250°C at 100 bars pressure in Dickson-type, gold-bag rocking autoclaves. The in-situ chemistry of the hydrothermal fluids was modeled and the chemical affinities for all possible mineral precipitation reactions (contained within the extensive database) were calculated using the EQ3/6 program.

In the 250°C experiment the calculations suggest that a zeolite mineral would be expected to form. Analyses of the run products showed that not only had the wafer been extensively corroded and the glass shards replaced by clinoptilolite, but pure clinoptilolite had precipitated directly from solution. In the 150°C experiment, although clay minerals were thermodynamically favored to form in the first half of the experiment, by the end of the run a zeolite mineral was predicted to form. Analyses of the run products showed no well-formed secondary minerals (clays or zeolites) had formed. At the lower temperature the effects of precipitation kinetics may preclude the formation of the zeolite within the time span of this experiment. In general the observations are in relatively good agreement with the geochemical model calculations. This type of study demonstrates the interpretive/predictive capabilities of a combined experimental/geochemical modeling approach to studies of nuclear waste isolation. This combined approach will aid in satisfying licensing requirements to assure long-term performance.
Transport of Radionuclides by Conncentrated Brine in a Porous Medium with Micropore-Macropore Structure
Authors: Hassanizadeh S. Majid
Published: June 2019

This work concerns itself with the study of effects of soil aggregation and high salt concentrations on the transport of radionuclides by concentrated brine flowing through an aggregated porous medium. The medium is considered to be composed of porous rock aggregates separated by macropores through which the brine flows and transport of salt and radionuclides takes place. The aggregates contain dead-end pores, cracks, and stationary pockets collectively called micropores. The micropore space does not contribute to the flow, but it serves as a storage for salt and radionuclides. Adsorption of radionuclides takes place at internal surfaces of aggregates where we assume that a linear equilibrium isotherm describes the process.

A one-dimensional numerical model is developed which is based on two sets of equations: one set for the flow and transport of salt and another set for transport of radionuclides. Results of numerical experiments clearly indicate that that. the existence of high salt concentrations markedly reduces the peak of nuclides concentration and slows down their movement. Also, it is found that diffusive mass exchange between macropores and aggregates results in a pronounced lowering of the radionuclides concentration peaks.
Influence of stress on structural and dielectric anomaly of Bi2(Zn1/3Ta2/3)207 thin films
Authors: Noh Jun Hong , Hong Hee Bum , Hong Kug Sun
Published: June 2019

Bi2(Zn1/3Ta2/3)2O7 (BZT) thin films were grown on the (111) oriented Pt/TiOx/SiO2/Si substrates using a pulsed laser deposition (PLD) technique. BZT thin films deposited at an oxygen partial pressure of 400 mTorr have the non-stoichiometric anomalous cubic phase despite the BZT target was the monoclinic phase. Compositions, the lattice mismatch, the interfacial layer and the residual stress in the film were investigated as the factors which may affect the formation of the anomalous cubic phase. Among them, the coherent interfacial layer which formed at high oxygen pressures resulted in the formation of the cubic phase by reducing the internal stress.
Thermal stress relaxation of plasma enhanced chemical vapour deposition silicon nitride
Authors: Morin P. , Martinez E. , Wacquant F. , Regolini J. L.
Published: June 2019

Mechanical and thermal properties of silicon nitride films deposited by different plasma process type have been studied. The initial mechanical stress, thickness and hydrogen content have been evaluated respectively by wafer curvature measurements, ellipsometry and Fourier Transform Infra Red spectrometry. These nitrides presented as-deposited stress values ranging from compressive to tensile. High temperature Rapid Thermal Anneal (RTA) at 1100°C or longer thermal treatments at medium temperature, from 700°C to 850°C were carried out on these materials. The evolution of their properties along the different anneals have been measured and compared to the behaviour of high temperature thermal nitride. One can observe that these stoechiometric plasma nitrides have shifted to an equilibrium tensile stress around 1100-1200 Mpa when submitted to the RTA, independently of their initial stress values. Results are interpreted in terms of H desorption and Si-N bond formation. Chemical reaction Si2-N-H + 2 N-H → 2 Si-N + NH3 appears to be the best candidate to figure out the phenomena.
Correlation Between Elastic Constants and Magnetic Anisotropy in Co/Pt Superlattice Thin Films
Authors: Nakamura Nobutomo , Ogi Hirotsugu , Ono Teruo , Hirao Masahiko , Yasui Takeshi , Matsuda Osamu
Published: June 2019

In this paper, we study contribution of the magnetoelastic anisotropy effect on perpendicular magnetic anisotropy of Co/Pt superlattice thin films. The effective-magnetic anisotropy energy was measured for Co/Pt thin films with a constant Co-layer thickness (4 Å) deposited on silicon substrate by the ultrahigh-vacuum deposition method. As the Pt-layer thickness increases, the effective-magnetic anisotropy energy increases and decreases after showing a maximum at the Pt-layer thickness of 12 Å. This behavior can be explained only by the magnetoelastic anisotropy effect, that is, elastic-strain energy released through the magnetostriction effect with the strain-dependent elastic constants.
Lidar Technology Role in Future Robotic and Manned Missions to Solar System Bodies
Authors: Baize Rosemary R. , Amzajerdian Farzin , Tolson Robert , Davidson John , Powell Richard W. , Peri Frank
Published: June 2019

Future planetary exploration missions will require safe and precision soft-landing to target scientifically interesting sites near hazardous terrain features, such as escarpments, craters, slopes, and rocks. Although the landing accuracy has steadily improved over time to approximately 35 km for the recent Mars Exploration Rovers due to better approach navigation, a drastically different guidance, navigation and control concept is required to meet future mission requirements. For example, future rovers will require better than 6 km landing accuracy for Mars and better than 1 km for the Moon plus 100 m maneuvering capability to avoid hazards. Laser Radar or Lidar technology can be the key to meeting these objectives since it can provide highresolution 3-D maps of the terrain, accurately measure ground proximity and velocity, and determine atmospheric pressure and wind velocity. These lidar capabilities can enable the landers of the future to identify the pre-selected landing zone and hazardous terrain features within it, determine the optimum flight path, having atmospheric pressure and winds data, and accurately navigate using precision ground proximity and velocity data. This paper examines the potential of lidar technology in future human and robotic missions to the Moon, Mars, and other planetary bodies. A guidance and navigation control architecture concept utilizing lidar sensors will be presented and its operation will be described. The performance and physical requirements of the lidar sensors will be also discussed.
Microstructure and Weibull distribution of rupture strength of clay-talc ceramics
Authors: Zerbo L. , Seynou M. , Sorgho B. , Lecomte-Nana G. , Gomina M. , Blanchart P.
Published: June 2019

Abstract The mechanical properties of clay-talc ceramics containing 0 to 10 wt% of talc fired at 1100 °C were obtained by flexural measurements. With the average value of flexural strength of 23.1 MPa, the sample with 5 wt% of talc (G5) was the strongest and it had the lowest value of interconnected pore (64%). The scattering of strength values was described with the Weibull distribution model. For all samples, Weibull plots showed either a typical linear behavior or a multi-stage response and the Weibull modulus varied in a large range of 3 to 14, depending on the ceramic type and on the applied load. Interconnections between pores formed a network of possible failures under the stress field, resulting in a change of Weibull plots. Reducing the grain size range and the pore interconnectivity led to a reduced strength distribution. The flaw size range had a unimodal distribution for sample G5 with homogeneous microstructure and correspondingly a Weibull modulus m=9.79.
Study of ZnAl2O4 spinel nanoparticles synthesized using gelatin as organic precursor
Authors: Macedo H. P. , Medeiros R. L. B. A. , Nascimento R. A. B. , Oliveira A. A. S. , Figueredo G. P. , Braga R. M. , Melo D. M. A.
Published: June 2019

Abstract In this work, zinc aluminate spinel powders were prepared by a fast, simple, eco-friendly and low-cost modified Pechini method using commercial gelatin as the organic precursor. The materials were calcinated at 600, 700 and 800 °C and characterized by thermogravimetric analysis, in situ and ex situ X-ray diffraction (XRD), N2-adsorption/desorption isotherms and scanning electron microscopy. The results showed that single phase ZnAl2O4 particles with spinel structure were successfully obtained resulting in a high purity, nanometric, homogeneous and mesoporous materials. The in situ XRD results showed that the crystalline spinel structure of ZnAl2O4 started forming at a temperature lower than 600 °C, revealing powders with crystallite size smaller than 40 nm, which increased with increasing the temperature (91% of increase between 600 and 800 °C). The effect of calcination time showed that the materials calcinated at 600 °C for 3 h presented the higher percentage of crystallite growth due to the increase of crystallinity. The ZnAl2O4 samples retained their pore size up to 700 °C.
Thermal behavior (TG-DTA-TMA), sintering and properties of a kaolinitic clay from Buenos Aires Province, Argentina
Authors: Conconi M. S. , Morosi M. , Maggi J. , Zalba P. E. , Cravero F. , Rendtorff N. M.
Published: June 2019

Abstract The technological properties of a local kaolin, considered as a potential industrial material, were correlated with the thermal behavior and sintering processes carried out through a series of thermochemical analyses. The chemical and mineralogical characterization of the material was carried out, together with a simple microstructural characterization. The used material corresponded to the kaolinized basement rocks (saprolite zone) mined at La Verónica quarry, Chillar area, Azul County, Argentina. The complete kaolinite-metakaolinite-spinel-mullite thermal series was characterized. Sintering behavior was studied; a viscous phase sintering mechanism was proposed. Apparent density and porosity of fired ceramics were measured. A light-firing color was confirmed by colorimetry. The viscous phase mechanism was possibly described thanks to the multi-technique thermal behavior analysis complemented by XRD analysis. These results permitted to establish formulation and processing strategies of ceramic materials based on the studied clay. The possible applications include: tile manufacturing, sanitary ware, tableware, kaolinitic proppants, chamotte and refractory materials.
Serum proteinogram of the Campeiro horse
Authors: Souza A.F. , Schade J. , Ramos A.F. , Albuquerque M.S.M. , Fonteque G.V. , Costa D. , Muller T.R. , Fonteque J.H.
Published: June 2019

ABSTRACT The aim of this study to measure the fractions of the total serum proteins of the Campeiro horse and identify the influences of biological variants. Blood samples were taken in 138 horses of the breed Campeiro for measuring the concentration of total serum protein by the biuret method. Serum concentrations of protein fractions were measured by electrophoresis using agarose gel. Groups were formed according to age, sex and reproductive condition. The average values of serum fractions: albumin (2.85±0.36g/dl), alpha 1 (0.28±0.11g/dl), alpha 2 (0.26±0.08g/dL) beta 1 (0.57±0.15g/dl), beta 2 (0.89±0.28g/dL), gamaglobulinas (1.86±0.34g/dL), albumin/globulin ratio (0.75±0.18) and 2.5% percentile and 97.5% had slight differences in relation to the reference interval proposed for the species. They observed higher values of alpha 1 and 2 globulins in the group from that had six to eight years old and gammaglobulins in group above 13 years old. Serum protein concentrations were similar in horses and mares and between non-pregnant and pregnant. Sex and pregnancy status did not affect serum proteinogram. Alpha and gammaglobulins have higher values as the age increases. Serum proteinogram of Campeiro horses shows variations that have to be considered in the interpretation of laboratory tests.
Prevalence of bovine tuberculosis in the Aksu Region of Xinjiang, China, between 1985 and 2016
Authors: Liu Y.H. , Kang Q. , Yang B. , Li F. , Li X.Q. , Zhang L. , Zhao L.
Published: June 2019

ABSTRACT Prevalence of bovine tuberculosis infection in cattle in Aksu Prefecture determined by intradermal tuberculin skin test (TST), between 1985 and 2016. Cattle were analyzed according to region, feeding pattern, herds and age. A total of 890,009 cattle were tested, with overall bovine tuberculosis prevalence of 0.13% (1172/890009). Statistically significant difference was found in feeding pattern and herds. Prevalence in cows (0.19%, 615/327022) was higher than that in beeves (P< 0.01, OR= 1.903, 95% CI = 1.696 to 2.134). Significant difference (P< 0.01; OR= 2.238, 95%; CI= 1.937 to 2.585) was evident for rates for bovine tuberculosis in the peasant household (0.12%, 942/802343) and farm groups (0.26%, 230/87666). The overall prevalence of bTB was decreased in the Aksu Prefecture, especially the positive rate was under 0.1% in 2010s. We concluded that the control measures forbovine tuberculosis in the Aksu region cattle herds are effective.
Caracterização de biossólido e potencial de uso na produção de mudas de Schinus terebinthifolia Raddi
Authors: Abreu Alan Henrique Marques de , Alonso Jorge Makhlouta , Melo Lucas Amaral de , Leles Paulo Sérgio dos Santos , Santos Gabriel Rocha dos
Published: June 2019

RESUMO O presente trabalho teve como objetivo caracterizar técnica, química e biologicamente o biossólido proveniente da estação de tratamento de esgoto (ETE) de Alegria, Rio de Janeiro, e inferir sobre sua aptidão como componente do substrato para produção de mudas de Schinus terebinthifolia Raddi (aroeira pimenteira). Foram coletadas amostras significativas do biossólido, submetidas às análises química e biológica em um laboratório especializado, atendendo às especificações da legislação vigente (Resolução CONAMA nº 375/2006). No viveiro, foram testadas quatro diferentes formulações de substrato, compostas de diferentes proporções volumétricas de substrato comercial (SC) e biossólido (BIO), consistindo nos seguintes tratamentos: T1 (100% SC + 0% BIO); T2 (75% SC + 25% BIO); T3 (50% SC + 50% BIO); e T4 (0% SC + 100% BIO). O delineamento experimental foi o inteiramente casualizado, com 4 tratamentos, 4 repetições de 18 mudas. O biossólido atendeu às especificações da legislação quanto à sua composição. Aos 120 dias após a semeadura foram mensuradas a altura da parte aérea e o diâmetro do coleto, observando que o crescimento das mudas foi diretamente proporcional à concentração de biossólido no substrato. O biossólido da ETE Alegria atende à legislação de uso agrícola e mostrou ser viável tecnicamente para a produção de mudas de aroeira pimenteira.
Remoção simultânea de material orgânico, nitrogênio e fósforo em um reator em bateladas sequenciais com biofilme de leito móvel operado pelo processo anaeróbio-anóxico-óxico
Authors: Bueno Rodrigo de Freitas , Campos Fábio , Rivera Marianella Munoz , Lenis Carolina , Piveli Roque Passos
Published: June 2019

RESUMO Neste estudo, foi avaliado o desempenho de um reator em bateladas sequenciais com biofilme de leito móvel operado pelo processo anaeróbio-anóxico-óxico (A2O), aplicado à remoção simultânea de material orgânico, nitrogênio e fósforo de esgoto sanitário. Utilizaram-se dois reatores com volume útil de 36 L cada, sendo que um deles recebeu anéis plásticos móveis do tipo Kaldnes®, com área superficial específica estimada em 310 m2/m3 que ocuparam 50% do volume útil do reator (denominado aqui de MBSBBR). O estudo foi conduzido com tempo de retenção de sólidos (TRS) de 12 dias, tempo de retenção hidráulico (TRH) de 6 horas, taxa de alimento/microrganismo (A/M) de 0,4 a 0,5 gDQO/SSV.d, oxigênio dissolvido (OD) na faixa de 0,3-0,8 mgO2/L e taxas de aplicação de carga orgânica, nitrogênio e fósforo de 47,2 gDQO/L.d, 5,4 gNTK/L.d e 0,4 gP/L.d, respectivamente. Os resultados de eficiência de remoção de demanda química de oxigênio (DQO), N-NH3 e fósforo foram de 91,1, 90,5 e 85,4% para o reator MBSBBR e de 89,5, 91,6 e 84,4% para o reator RBS, respectivamente. Os resultados do teste estatístico de ANOVA foram aplicados às principais variáveis estudadas, e os valores convergiram para valores de f observado < f crítico . Dessa forma, considera-se que houve similaridade de desempenho nos reatores MBSBBR e RBS. Conclui-se que a introdução do meio suporte não trouxe benefícios ao tratamento em termos de remoção de nutrientes. No entanto, o estudo mostrou que é possível de se obter elevada remoção de nitrogênio, em baixas concentrações de OD, o que se torna vantajoso para o tratamento de esgoto com elevada concentração de nitrogênio.
Sustentabilidade do licenciamento ambiental minerário em Minas Gerais: caso aplicado
Authors: Santos Paula Fernandes dos , Borges Luís Antônio Coimbra
Published: June 2019

RESUMO A avaliação de impactos ambientais, introduzida por meio da Política Nacional de Meio Ambiente (PNMA), ganhou espaço primordialmente dentro do licenciamento ambiental, cujo modelo atual é questionado pela sua ineficácia em compensar ao ambiente a perda dos recursos naturais. Este estudo teve como objetivo analisar de forma técnica e legal o licenciamento ambiental minerário na Região do Alto São Francisco, Minas Gerais, por intermédio do histórico e fluxo atual dos processos, do levantamento de dados dos de Estudos de Impacto Ambiental, do cumprimento dos Termos de Referência e da legislação ambiental, analisando estes dados pelo método Analytic Hierarchy Process (AHP). Os resultados demonstraram que o licenciamento ambiental não cumpre a função de compensar os impactos socioambientais causados pela atividade nem os requisitos legais obrigatórios ao processo.
Apoio Pedagógico como proposta de educação para todos
Authors: Donida Lais Oliva , Santana Ana Paula
Published: June 2019

Resumo Na última década, a partir de políticas públicas de acesso à universidade, o perfil dos estudantes modificou-se. Se antes havia um público de elite intelectual, de classe social privilegiada, agora tem-se uma maior heterogeneidade. Para atender esse público, há programas de Apoio Pedagógico. Logo, o presente trabalho buscou analisar as ações do Apoio Pedagógico de uma universidade do sul do Brasil. Como metodologia, foi realizada pesquisa qualitativo-descritiva que envolveu análise documental a respeito das políticas públicas e as ações institucionais do Apoio Pedagógico e entrevista semiestruturada aplicada presencialmente com os integrantes da equipe do Apoio Pedagógico: a tutora, o profissional da CAE e três estudantes com dificuldades de leitura e/ou escrita e um com Transtorno Funcional. Os resultados apontam que, embora a universidade ofereça programas de apoio para os estudantes, ainda não é eficiente, pois as ações não atingem todos os estudantes, a adesão dos cursos aos programas ofertados pelo Apoio Pedagógico é baixa e a divulgação ainda é insuficiente. Os universitários, por sua vez, sentem-se excluídos pelos docentes e demais colegas e referem que suas dificuldades acadêmicas atrapalham sua trajetória com qualidade na instituição e até a permanência de cada um na instituição. Assim, há necessidade de medidas para que se promova a inclusão e seja possível uma universidade para todos, tais como: curso de formação docente, programa de apoio mais direcionado para cada necessidade do estudante, oficinas de letramento, palestras para a comunidade acadêmica, dentre outras.
Seismic bearing capacity of strip footing placed on a reinforced slope
Authors: Halder K. , Chakraborty D.
Published: June 2019

The study estimates the lower bound values of the seismic bearing capacity of a strip footing placed on a reinforced cohesionless soil slope. The influence of slope angle, soil friction angle, horizontal seismic acceleration coefficient, depth of first reinforcement layer from the footing base and vertical spacing between two reinforcement layers was investigated. The effectiveness of using a reinforcement layer is expressed by an efficiency factor, which is the ratio of the bearing capacity factor for reinforced and unreinforced slopes. The bearing capacity increases by approximately 15 times for a few cases with a single layer reinforced slope. With the inclusion of another layer of reinforcement, this improvement is doubled. The influence of setback position of footing with respect to the slope edge is also investigated for a few representative slopes subjected to both static and seismic loading. Beyond a critical distance, the setback effect is negligible. Several design charts are presented. Stress contours are plotted to understand the failure mechanisms of unreinforced and reinforced slopes.
Seismic sliding stability analysis of reinforced soil retaining walls
Authors: Xu P. , Hatami K. , Jiang G.
Published: June 2019

The Coulomb linear slip plane is adopted in most of the current design guidelines for reinforced soils walls based on the assumption that the reinforced zone acts as a rigid body. However, among major shortcomings of the Coulomb linear slip plane assumption is that its geometry is not consistent with the two-part wedge failure geometry that is typically observed in many model tests and numerical simulations, and the influence of reinforcement design on the sliding stability of reinforced mass cannot be included in the analysis. In this paper, a kinematic limit analysis method is developed for sliding stability calculations of reinforced soil retaining walls subjected to ground acceleration, which is based on the more commonly-observed, two-part wedge failure mechanism. The proposed analysis method is validated against the results of two shaking table model tests. It is subsequently used to investigate the influence of reinforcement and backfill properties, as well as those of vertical acceleration and wall height, on the predicted sliding yield acceleration and failure plane inclination angle in the reinforced zone of the reinforced soil retaining wall systems.
Acción colectiva y desarrollo rural: las instituciones de organización de la calidad
Authors: Macías Vázquez Alfredo
Published: June 2019

Propósito:  Desde un enfoque institucional, pretendemos iniciar un debate analizando las instituciones de acción colectiva más representativas de la organización de la calidad a escala territorial, donde se generan procesos de labelización que permiten a las comunidades locales desarrollar un cierto poder de mercado para fijar el valor generado en el mismo territorio.Descripción: En el trabajo, analizamos cómo las carencias a nivel de las relaciones de cooperación entre los actores condicionan la potencialidad de este tipo de instituciones para enfrentar los desafíos para un desarrollo rural sostenible en la globalización.Punto de vista: En la literatura académica, ha existido una escasa atención al análisis de la acción colectiva de los activos inmateriales comunes de las comunidades locales. Conclusiones: la organización colectiva de la calidad representa un actor colectivo importante desde el punto de vista de orientar estratégicamente el proceso de innovación tecnológica, con todas las consecuencias económicas e institucionales que ello conlleva (Macías y Vence, 2013). Si logramos que realmente una organización cooperativa de estas características asuma un rol protagonista en la difusión de innovaciones tecnológicas, seguramente estaremos en mejores condiciones de pensar y proyectar estrategias de desarrollo rural más eficaces y más integrales.
O meio do campo em disputa e as implicações da "nova" Classe Média Rural na ação pública
Authors: Soldera Denis , Niederle Paulo Andre
Published: June 2019

Este artigo discute as implicações que as disputas da classe média rural determinam à ação pública, sobretudo à ressignificação da Agricultura Familiar enquanto categoria sociopolítica. Valendo-se de pesquisa documental e bibliográfica, busca-se resgatar a trajetória histórica das políticas para o meio rural a fim de compreender como foram forjados os atuais referenciais de políticas para o desenvolvimento rural. Ademais, demonstra-se que em termos de embates políticos, as recentes interpretações acerca da classe média rural visam sustentar e legitimar as ações de um ou outro referencial de desenvolvimento rural. Verifica-se que as interpretações têm questionado a capacidade de reprodução social dos agricultores mais pobres por vias de incremento produtivo e evidenciam o aumento da participação de políticas sociais na composição da renda desses indivíduos. Isso tem conduzido à disputa de uma ampla base social e política a fim de legitimar as ações e os recursos destinados a determinadas políticas e também ao questionamento da classe média identificada e abarcada pela categoria Agricultura Familiar.
Topical Issues of Determining a Vehicle Driver's Intoxication in the Investigation of Road Traffic Offences
Authors: Aksenova-Sorokhtei Julia , Baranovskaya Elena , Kuzmina Olga , Makhanek Аnna
Published: June 2019

Alcohol and drug abuse hold a special place among the phenomena accompanying the modern civilization because they have a negative impact on all aspects of society. One of the most dangerous types of crimes committed under the influence is road traffic accidents. The negative trend of this category of crimes necessitates their efficient investigation, the success of which greatly depends on the right measures of legal coercion aimed at determining the condition of the person driving a vehicle. Measures of administrative, administrative procedure and criminal procedure coercion are especially important in this process. The paper presents a systemic analysis of the norms of criminal and administrative law as well as criminal and administrative process that determine the procedure of testing and medical screening for intoxication. The authors also examine the issues of ordering and carrying out forensic examination to determine the condition of intoxication, and the procedure of acquiring biological samples for testing. They analyze court practice in the spheres of both administrative jurisdiction and criminal court procedure. The authors come to the conclusion that the procedure of screening a person driving a vehicle should be improved. Most problems associated with it are caused by the legal ambiguity regarding the choice of the medical institution that should carry out the chemical and toxicological analysis of bodily fluids. Besides, the law does not have any provisions for the double-screening of biological material to identify narcotics and psychoactive substances in the cases when preliminary screenings results are negative, as they often do not distinguish some types of narcotics, such as spices. In order to identify the condition of intoxication it is necessary for the medical screening to follow the procedure set out in the criminal procedure legislation, which should include obtaining of biological samples for testing and further forensic chemical and toxicological expertise.
The Constitutional Rules of Succession to the Institution of Monarch in Lesotho
Authors: 'Nyane Hoolo
Published: June 2019

The rules that govern succession to the office of King in Lesotho are largely customary. The Constitution of Lesotho, 1993 provides that succession to the office of King shall be regulated in terms of customary law; the Constitution itself does not provide for the substantive and procedural rules governing succession. The zenith of customary rules is that succession to kingship in Lesotho is based on the principle of primogeniture. The primogeniture rule has always presented problems of application in Lesotho; more so in the era of equality and democracy. This paper critiques the rules of succession to the office of King. It contends that by leaving the regulation of succession exclusively to customary law without clear articulation in the Constitution, the Constitution is unduly yielding to a system of law (customary law) which is not only subservient to the Constitution but also based on a different set of values. The paper recommends that the rules of succession must be codified in the Constitution and must be realigned with contemporary notions of constitutionalism and equality.
Decision support for evaluating energy demand in vinification processes using fuzzy sets theory
Authors: Musee N , Lorenzen L , Aldrich C
Published: June 2019

The current trend associated with high energy demand, depletion of energy reserves and low potential of renewable energy sources linked with strong industrial growth, is increasingly becoming unsustainable. As a result, production costs have increased considerably in the process industries, mainly owing to skewed energy demand and supply realities. A feasible strategy for meeting these challenges is to reduce energy consumption per unit throughput. However, to obtain a workable solution, decision makers may have to deal with energy management variables that are ambiguous, which makes solving the energy minimization problem with conventional numerical approaches very difficult. In this paper, we consider an alternative approach based on fuzzy logic to qualitatively evaluate the energy demand associated with an industrial cooling process. The model was formulated based on Mamdani fuzzy logic inferencing and implemented in MATLAB 6.5 via the Fuzzy Logic toolbox. The energy demands pertaining to specific variables were independently estimated, followed by an estimate of the overall energy consumption. The procedure is demonstrated via a case study of cooling at the maceration stage of a vinification process in the wine industry.
Technologies that contribute to reducing environmental impacts of electrical production
Authors: Kahn M T E , Fritz W
Published: June 2019

The World Summit on Sustainable Development (WSSD) was attended by approximately 21 000 international delegates in Johannesburg, South Africa in 2002. The aim was to institute ecologically sound environmental management. Research has shown that fossil fuel or coal fired power plants are the major cause of air pollution in electricity generation. This paper seeks to show technologies that can contribute to reducing the environmental impacts of electricity production, via emission control systems, industry energy policy, renewable energy technologies etc. and the promotion of active research and development in alternative energy applications in Africa. Innovative energy technology research and development and applications such as smaller scale distributed generation and solid state lighting (SSL) are seen as capable of adding a positive contribution in this area.
Use of artificial roughness to enhance heat transfer in solar air heaters – a review
Authors: Kumar Thakur Sanjay , Thakur N.S. , Kumar Anoop , Mittal Vijay
Published: June 2019

Improvement in the thermo hydraulic performance of a solar air heater can be done by enhancing the heat transfer. In general, heat transfer enhancement techniques are divided into two groups: active and passive techniques. Providing an artificial roughness on a heat transferring surface is an effective passive heat transfer technique to enhance the rate of heat transfer to fluid flow. In this paper, reviews of various artificial roughness elements used as passive heat transfer techniques, in order to improve thermo hydraulic performance of a solar air heater, is done. The objective of this paper is to review various studies, in which different artificial roughness elements are used to enhance the heat transfer rate with little penalty of friction. Correlations developed by various researchers with the help of experimental results for heat transfer and friction factor for solar air heater ducts by taking different roughened surfaces geometries are given in tabular form. These correlations are used to predict the thermo hydraulic performance of solar air heaters having roughened ducts. The objective is to provide a detailed review on heat transfer enhancement by using an artificial roughness technique. This paper will be very helpful for the researchers who are researching new artificial roughness for solar air heater ducts to enhance the heat transfer rate and comparing with artificial roughness already studied by various researchers.
Crude oil price hikes and issues for energy security for Southern Africa
Authors: Nkomo Jabavu Clifford
Published: June 2019

This paper addresses a number of issues related to crude oil prices, focusing on Southern Africa. It begins by analysing oil price movements from 1970 to 2008, and examines various factors that may have contributed to the sharp rise and fall in prices. A characteristic feature in the oil market is the time lags it takes to react to price changes. A high oil intensity of GDP makes the economy vulnerable to oil price increases, so that countries with a high oil/GDP ratio are harder hit than others. There are two main issues for energy security: first, on whether the potential use of the oil weapon can be taken seriously; and second, how to minimize vulnerability to oil supply shocks by reducing oil dependence and by a developing or enlarging a strategic stockpile of oil.
Measuring the indirect costs associated with the establishment of a wind farm: An application of the contingent valuation method
Authors: Du Preez Mario , Menzies Greig , Sale Michael , Hosking Stephen
Published: June 2019

Although a green energy source, the location of electrical generating wind turbines may cause a disamenity effect (negative externality). The establishment of a wind farm is known as a locally undesirable land use (LULU) and leads to the not in my backyard syndrome (NIMBY). In an application of the contingent valuation method (a survey technique which elicits individuals’ preferences and measures these preferences in monetary terms) a willingness to accept a framework was used to estimate the aggregate annual compensation required to allow the construction of a wind farm near Jeffrey’s Bay, South Africa. This compensation amounted to R490 695. A binary choice Logit analysis found that retirement status, concern about climate change, concern about view shed impacts and the offer amount are important predictors of voting for or against the project.
Energy consumption and real GDP: Panel co-integration and causality tests for sub-Saharan African countries
Authors: Fowowe Babajide
Published: June 2019

This paper investigates the causal relationship between energy consumption and real GDP in 14 Sub-Saharan African countries over the period 1971–2004. The results of panel co-integration tests showed that energy consumption and real GDP do not have a stable long-run equilibrium relationship. We find that for all members of the panel, there is homogenous causality from energy consumption to real GDP and vice versa. This bi-directional causality supports the feedback hypothesis.