Energy consistent discontinuous Galerkin methods for a quasi-incompressible diffuse two phase flow model

We design consistent discontinuous Galerkin finite element schemes for the approximation of a quasi-incompressible two phase flow model of Allen–Cahn/Cahn–Hilliard/Navier–Stokes–Korteweg type which allows for phase transitions. We show that the scheme is mass conservative and monotonically energy dissipative. In this case the dissipation is isolated to discrete equivalents of those effects already causing dissipation on the continuous level, that is, there is no artificial numerical dissipation added into the scheme. In this sense the methods are consistent with the energy dissipation of the continuous PDE system.

Recent progress in understanding and projecting regional and global mean sea-level change

Considerable progress has been made in understanding the present and future regional and global sea level in the 2 years since the publication of the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change. Here, we evaluate how the new results affect the AR5’s assessment of (i) historical sea level rise, including attribution of that rise and implications for the sea level budget, (ii) projections of the components and of total global mean sea level (GMSL), and (iii) projections of regional variability and emergence of the anthropogenic signal. In each of these cases, new work largely provides additional evidence in support of the AR5 assessment, providing greater confidence in those findings. Recent analyses confirm the twentieth century sea level rise, with some analyses showing a slightly smaller rate before 1990 and some a slightly larger value than reported in the AR5. There is now more evidence of an acceleration in the rate of rise. Ongoing ocean heat uptake and associated thermal expansion have continued since 2000, and are consistent with ocean thermal expansion reported in the AR5. A significant amount of heat is being stored deeper in the water column, with a larger rate of heat uptake since 2000 compared to the previous decades and with the largest storage in the Southern Ocean. The first formal detection studies for ocean thermal expansion and glacier mass loss since the AR5 have confirmed the AR5 finding of a significant anthropogenic contribution to sea level rise over the last 50 years. New projections of glacier loss from two regions suggest smaller contributions to GMSL rise from these regions than in studies assessed by the AR5; additional regional studies are required to further assess whether there are broader implications of these results. Mass loss from the Greenland Ice Sheet, primarily as a result of increased surface melting, and from the Antarctic Ice Sheet, primarily as a result of increased ice discharge, has accelerated. The largest estimates of acceleration in mass loss from the two ice sheets for 2003–2013 equal or exceed the acceleration of GMSL rise calculated from the satellite altimeter sea level record over the longer period of 1993–2014. However, when increased mass gain in land water storage and parts of East Antarctica, and decreased mass loss from glaciers in Alaska and some other regions are taken into account, the net acceleration in the ocean mass gain is consistent with the satellite altimeter record. New studies suggest that a marine ice sheet instability (MISI) may have been initiated in parts of the West Antarctic Ice Sheet (WAIS), but that it will affect only a limited number of ice streams in the twenty-first century. New projections of mass loss from the Greenland and Antarctic Ice Sheets by 2100, including a contribution from parts of WAIS undergoing unstable retreat, suggest a contribution that falls largely within the likely range (i.e., two thirds probability) of the AR5. These new results increase confidence in the AR5 likely range, indicating that there is a greater probability that sea level rise by 2100 will lie in this range with a corresponding decrease in the likelihood of an additional contribution of several tens of centimeters above the likely range. In view of the comparatively limited state of knowledge and understanding of rapid ice sheet dynamics, we continue to think that it is not yet possible to make reliable quantitative estimates of future GMSL rise outside the likely range. Projections of twenty-first century GMSL rise published since the AR5 depend on results from expert elicitation, but we have low confidence in conclusions based on these approaches. New work on regional projections and emergence of the anthropogenic signal suggests that the two commonly predicted features of future regional sea level change (the increasing tilt across the Antarctic Circumpolar Current and the dipole in the North Atlantic) are related to regional changes in wind stress and surface heat flux. Moreover, it is expected that sea level change in response to anthropogenic forcing, particularly in regions of relatively low unforced variability such as the low-latitude Atlantic, will be detectable over most of the ocean by 2040. The east-west contrast of sea level trends in the Pacific observed since the early 1990s cannot be satisfactorily accounted for by climate models, nor yet definitively attributed either to unforced variability or forced climate change.

Underreporting of Energy Intake in Brazilian Women Varies According to Dietary Assessment: A Cross-Sectional Study Using Doubly Labeled Water

Objective Underreporting of energy intake is prevalent in food surveys, but there is controversy about which dietary assessment method provides greater underreporting rates. Our objective is to compare validity of self-reported energy intake obtained by three dietary assessment methods with total energy expenditure (TEE) obtained by doubly labeled water (DLW) among Brazilian women. Design We used a cross-sectional study. Subjects/setting Sixty-five females aged 18 to 57 years (28 normal-weight, 10 over-weight, and 27 obese) were recruited from two universities to participate. Main outcome measures TEE determined by DLW, energy intake estimated by three 24-hour recalls, 3-day food record, and a food frequency questionnaire (FFQ). Statistical analyses performed Regression and analysis of variance with repeated measures compared TEE and energy intake values, and energy intake-to-TEE ratios and energy intake-TEE values between dietary assessment methods. Bland and Altman plots were provided for each method. chi(2) test compared proportion of underreporters between the methods. Results Mean TEE was 2,622 kcal (standard deviation [SD] =490 kcal), while mean energy intake was 2,078 kcal (SD=430 kcal) for the diet recalls; 2,044 kcal (SD=479 kcal) for the food record and 1,984 kcal (SD=832 kcal) for the FFQ (all energy intake values significantly differed from TEE; P<0.0001). Bland and Altman plots indicated great dispersion, negative mean differences between measurements, and wide limits of agreement. Obese subjects underreported more than normal-weight subjects in the diet recalls and in the food records, but not in the FFQ. Years of education, income and ethnicity were associated with reporting accuracy. Conclusions The FFQ produced greater under- and overestimation of energy intake. Underreporting of energy intake is a serious and prevalent error in dietary self-reports provided by Brazilian women, as has been described in studies conducted in developed countries.

Effects of N supply on the accumulation of photosynthetic pigments and photoprotectors in Gracilaria tenuistipitata (Rhodophyta) cultured under UV radiation

We have studied the effects of nitrate supply under photosynthetic active radiation (PAR) plus ultraviolet radiation (UVR) exposure on photosynthetic pigments (chlorophyll a and carotenoids), photoprotective UV screen mycosporine-like amino acids (MAAs), and photosynthetic parameters, including the maximum quantum yield (F(v)/F(m)) and electron transport rate (ETR) on the red agarophyte Gracilaria tenuistipitata. Apical tips of G. tenuistipitata were cultivated under ten different concentrations of NO(3)(-) for 7 days. It has been shown that G. tenuistipitata cultured under laboratory conditions has the ability to accumulate high amounts of MAAs following a nitrate concentration-dependent manner under PAR+UVR. Two MAAs were identified, shinorine and porphyra-334. The relative concentration of the first increased under high concentrations of nitrate, while the second one decreased. The presence of antheraxanthin is reported for the first time in this macro-algae, which also contains zeaxanthin, lutein, and beta-carotene. The accumulation of pigments, photoprotective compounds, and photosynthetic parameters of G. tenuistipitata is directly related to N availability. All variables decreased under low N supplies and reached constant maximum values with supplements higher than 0.5 mM NO(3)(-). Our results suggest a high potential to acclimation and photoprotection against stress factors (including high PAR and UVR) directly related to N availability for G. tenuistipitata.

Leptin and the Immune Response An Active Player or an Innocent Bystander?

Leptin is involved in the control of energy storage by the body. Low serum leptin levels, as seen in starvation, are associated with impaired inflammatory T cell responses that can be reversed by exogenous leptin. Common variable immunodeficiency (CVID) is characterized by hypogammaglobulinemia and recurrent infections. Several defects in T cell function have also been described, and allergy, autoimmune disease, and lymphomas or other malignancies can be present. Previous studies in Brazilian CVID patients have shown that, in contrast with mononuclear cells from healthy controls, CVID cells cultured with phytohemagglutinin and added leptin increased the proliferative response and decreased activation-induced apoptosis. Interleukin (IL)-2 and especially IL-4 production also increased significantly, although the effects of exposure to leptin were not observed uniformly in CVID patients. The majority, however, responded in some degree, and some exhibited completely restored values of the four parameters. These remarkable results indicate leptin could be used to improve immune function in these patients. On the other hand, we found no specific correlation between serum leptin levels and the number of infectious events over a 24-month period, presence of autoimmunity, allergies, or cancer in these patients. The results suggest that the absolute value of serum leptin does not determine the clinical behavior of patients or responses to leptin in vitro. Of note is the divergence between serum leptin, response to leptin in vitro, and the presence of autoimmunity, indicating the need to identify the cellular and molecular players involved in the regulation of the immune response by leptin in CVID.

Renewable energy education : Report from a field trip to Melbourne, Australia, and short visits to India and New Zealand During Nov/Dec 1992

During November and December 1992 I visited several groups involved with renewable energy, most of them dealing with education. These groups and their work are described briefly in this report. The groups in Melbourne, Australia have come a long way with education in this field and we have a lot to learn from them. Government funding is needed for large scale work, but useful work can still be done at the community level with much smaller budgets.

Solcellsdrivet FTX-system för miljonprogramshus : Tjärna Ängar, Borlänge

Projektet omfattade undersökning och framtagande av ett solcellssystem med förmåga att försörja ett FTX-system i ett flerbostadshus från miljonprogrammet med el. För att kunna bedöma storlek och utformning av komponenter har information tagits genom: Informationssökning via databaser, kurslitteratur och intervjuer Simuleringar av solceller i datorprogrammet PVSYST Modulering av ventilationskanaler i datorprogrammet MagiCAD Syftet var främst att undersöka om det gick att få fram ett teoretiskt fungerande system med avseende på både solceller och ventilation. Beroende på vad resultatet blev skulle även ekonomin i projektet undersökas. Undersökningen visade att det teoretiskt ska gå att installera solceller för elframställning som klarar av att täcka FTX-systemets elbehov på årsbasis. Solcellerna bedöms även producera tillräckligt med el för viss övrig elkrävande utrustning under stora delar av året. Det visade sig även att det skulle gå att få solcellerna ekonomiskt lönsamma om en kalkyltid på 14 år används. Metoden som använts för dessa resultat är noga beskriven och är med små förändringar tillämpbar för ett stort antal byggnader i det svenska byggnadsbeståndet. En viktig slutsats är att om fastighetsägarna kan se 15 år fram i tiden för en investering i solenergi, skulle det innebära inte bara miljömässiga utan även ekonomiska vinster. Det finns redan idag kunnande, teknik och produkter för att utvinna en stor del av fastigheternas elbehov genom solens energi.

Buried screen-printed contacts for silicon solar cells

A Simple way to improve solar cell efficiency is to enhance the absorption of light and reduce the shading losses. One of the main objectives for the photovoltaic roadmap is the reduction of metalized area on the front side of solar cell by fin lines. Industrial solar cell production uses screen-printing of metal pastes with a limit in line width of 70-80 μm. This paper will show a combination of the technique of laser grooved buried contact (LGBC) and Screen-printing is able to improve in fine lines and higher aspect ratio. Laser grooving is a technique to bury the contact into the surface of silicon wafer. Metallization is normally done with electroless or electrolytic plating method, which a high cost. To decrease the relative cost, more complex manufacturing process was needed, therefore in this project the standard process of buried contact solar cells has been optimized in order to gain a laser grooved buried contact solar cell concept with less processing steps. The laser scribing process is set at the first step on raw mono-crystalline silicon wafer. And then the texturing etch; phosphorus diffusion and SiNx passivation process was needed once. While simultaneously optimizing the laser scribing process did to get better results on screen-printing process with fewer difficulties to fill the laser groove. This project has been done to make the whole production of buried contact solar cell with fewer steps and could present a cost effective opportunity to solar cell industries.

Recuperação do cromo contido nas cinzas provenientes da incineração de resíduos sólidos das indústrias coureira e calçadista visando a obtenção de cromato de sódio (VI)

O processo de transformação da pele em couro envolve uma seqüência complexa de reações químicas e processos mecânicos, no qual o curtimento representa fundamental estágio, por propiciar à pele características como qualidade, estabilidade hidrotérmica e excelentes propriedades para uso. O sulfato básico de cromo trivalente é o agente curtente predominantemente empregado no curtimento de peles em todo o mundo. É produzido a partir do cromato de sódio, industrialmente obtido do minério de cromo. Consideráveis quantidades de resíduos sólidos contendo cromo são geradas pelas indústrias coureira e calçadista. Estes resíduos tem sido motivo de preocupação constante, uma vez que são considerados perigosos devido a presença do cromo. O processo de incineração destes resíduos é uma importante alternativa a ser considerada, em decorrência de suas características de redução de massa, volume e possibilidade de aproveitamento da energia térmica dos gases de combustão. O processo de incineração dos resíduos das indústrias coureira e calçadista dá origem a cinzas contendo cerca de 40% de cromo que pode ser submetida a um processo de recuperação. Este trabalho apresenta os resultados da pesquisa sobre a utilização das cinzas, provenientes da incineração dos resíduos sólidos da indústria coureira e da indústria calçadista, para a produção de cromato de sódio(VI). No processo de planejamento e de condução dos experimentos foram utilizadas as técnicas de Planejamento Fatorial 2k, Metodologia de Superfície de Resposta e Análise de Variância na avaliação da produção de cromato de sódio(VI). Os fatores investigados foram: temperatura, taxa de aquecimento, tempo de reação, vazão de ar e quantidade de dolomita. A partir das variáveis selecionadas identificaram-se como parâmetros importantes a temperatura e a taxa de aquecimento. As superfícies de resposta tridimensionais obtidas a partir dos modelos de segunda ordem ajustados aos dados experimentais, apresentaram o comportamento do efeito conjugado dos fatores temperatura e taxa de aquecimento sobre a variável resposta grau de oxidação, desde a temperatura de inicio da reação química até a temperatura limite utilizada industrialmente. As condições de operação do processo de produção de cromato de sódio(VI) foram otimizadas. Os níveis ótimos dos fatores de controle aplicados as cinzas dos resíduos da indústria calçadista, geradas em uma planta piloto com incinerador de leito fixo, com tecnologia de gaseificação e combustão combinadas, apresentaram um grau de oxidação superior a 96% para as cinzas coletadas no ciclone e de 99,5% para as cinzas coletas no reator de gaseificação. Os resíduos sólidos, as cinzas e o produto de reação foram caracterizados por análises químicas, fluorescência de raio-X, microscopia eletrônica de varredura e difração de raio-X.

An improved and fast UHPLC-PDA methodology for determination of L-ascorbic and dehydroascorbic acids in fruits and vegetables: evaluation of degradation rate during storage

This study provides a versatile validated method to determine the total vitamin C content, as the sum of the contents of L-ascorbic acid (L-AA) and dehydroascorbic acid (DHAA), in several fruits and vegetables and its degradability with storage time. Seven horticultural crops from two different origins were analyzed using an ultrahigh-performance liquid chromatographic–photodiode array (UHPLC-PDA) system, equipped with a new trifunctional high strength silica (100% silica particle) analytical column (100 mm×2.1 mm, 1.7 μm particle size) using 0.1% (v/v) formic acid as mobile phase, in isocratic mode. This new stationary phase, specially designed for polar compounds, overcomes the problems normally encountered in HPLC and is suitable for the analysis of large batches of samples without L-AA degradation. In addition, it proves to be an excellent alternative to conventional C18 columns for the determination of L-AA in fruits and vegetables. The method was fully validated in terms of linearity, detection (LOD) and quantification (LOQ) limits, accuracy, and inter/intraday precision. Validation experiments revealed very good recovery rate of 96.6±4.4% for L-AA and 103.1±4.8 % for total vitamin C, good linearity with r2-values >0.999 within the established concentration range, excellent repeatability (0.5%), and reproducibility (1.6%) values. The LOD of the method was 22 ng/mL whereas the LOQ was 67 ng/mL. It was possible to demonstrate that L-AA and DHAA concentrations in the different horticulture products varied oppositely with time of storage not always affecting the total amount of vitamin C during shelf-life. Locally produced fruits have higher concentrations of vitamin C, compared with imported ones, but vegetables showed the opposite trend. Moreover, this UHPLC-PDA methodology proves to be an improved, simple, and fast approach for determining the total content of vitamin C in various food commodities, with high sensitivity, selectivity, and resolving power within 3 min of run analysis.

Parallel Cyclostationarity-Exploiting Algorithm for Energy-Efficient Spectrum Sensing

The evolution of wireless communication systems leads to Dynamic Spectrum Allocation for Cognitive Radio, which requires reliable spectrum sensing techniques. Among the spectrum sensing methods proposed in the literature, those that exploit cyclostationary characteristics of radio signals are particularly suitable for communication environments with low signal-to-noise ratios, or with non-stationary noise. However, such methods have high computational complexity that directly raises the power consumption of devices which often have very stringent low-power requirements. We propose a strategy for cyclostationary spectrum sensing with reduced energy consumption. This strategy is based on the principle that p processors working at slower frequencies consume less power than a single processor for the same execution time. We devise a strict relation between the energy savings and common parallel system metrics. The results of simulations show that our strategy promises very significant savings in actual devices.

Análise do custo-benefício de sistemas de cobertas em edificações comerciais para o clima de Natal/RN visando eficiência energética

This research consists in studying the influence of the various type of construction systems of roofs with their energy efficiency as well as on the cost benefit for the commercial buildings on the temperatures condition of the city of Natal/RN. The main goal of this research is to analyze the cost benefit of the construction systems of roofs available on the market, taking into consideration the energy efficiency of the commercial buildings artificially air conditioned in order to be used by the projectors and to be adequated to the temperatures condition of the city of Natal/RN. The method of valuation of the cost benefit of roof systems consists in six steps: Features and simulation of the reference building; Analyze of sensitivity; Analyzes, features and simulation of alternatives of roof construction systems; Analyze of the cost of implementation; Analyze of the benefits of the alternatives comparing to the base case; And finally the analyze of the cost benefit. The model type chosen as reference was stores with pre molded buildings and system of roof with fiber ciment and ceiling . The thermal results showed the influence of the roof system on the energy efficiency of the building. The Final results of the simulations of the alternatives comes to a conclusion that the absortance is the variable that presents the best cost benefit relation and the reduction on the thermal transmittance still has limitations because of the high cost

Síntese e caracterização de NiO-CGO para anodo e eletrólitos sólidos e base de Céria para SOFC

The direct use of natural gas makes the Solid Oxide Fuel Cell (SOFC) potentially more competitive with the current energy conversions technologies. The Intermediate Temperature SOFC (IT-SOFC) offer several advantages over the High Temperature SOFC (HT-SOFC), which includes better thermal compatibility among components, fast start with lower energy consumption, manufacture and operation cost reduction. The CeO2 based materials are alternatives to the Yttria Stabilized Zirconia (YSZ) to application in SOFC, as they have higher ionic conductivity and less ohmic losses comparing to YSZ, and they can operate at lower temperatures (500-800°C). Ceria has been doped with a variety of cations, although, the Gd3+ has the ionic radius closest to the ideal one to form solid solution. These electrolytes based in ceria require special electrodes with a higher performance and chemical and termomechanical compatibility. In this work compounds of gadolinia-doped ceria, Ce1-xGdxO2-δ (x = 0,1; 0,2 and 0,3), used as electrolytes, were synthesized by polymeric precursors method, Pechini, as well as the composite material NiO - Ce0,9Gd0,1O1,95, used as anode, also attained by oxide mixture method, mixturing the powders of the both phases calcinated already. The materials were characterized by X ray diffraction, dilatometry and scanning electronic microscopy. The refinement of the diffraction data indicated that all the Ce1-xGdxO2-δ powders were crystallized in a unique cubic phase with fluorite structure, and the composite synthesized by Pechini method produced smaller crystallite size in comparison with the same material attained by oxide mixture method. All the produced powders had nanometric characteristics. The composite produced by Pechini method has microstructural characteristics that can increase the triple phase boundaries (TPB) in the anode, improving the cell efficiency, as well as reducing the mass transport mechanism effect that provokes anode degradation

Estudo de massa cerâmica triaxial visando à otimização do ciclo de queima da indústria de cerâmica estrutural

Over recent years the structural ceramics industry in Brazil has found a very favorable market for growth. However, difficulties related to productivity and product quality are partially inhibiting this possible growth. An alternative for trying to solve these problems and, thus, provide the pottery industry the feasibility of full development, is the substitution of firewood used in the burning process by natural gas. In order to contribute to this process of technological innovation, this paper studies the effect of co-use of ceramic phyllite and kaolin waste on the properties of a clay matrix, verifying the possible benefits that these raw materials can give to the final product, as well as the possibility of such materials to reduce the heat load necessary to obtain products with equal or superior quality. The study was divided into two steps: characterization of materials and study of formulations. Two clays, a phyllite and a residue of kaolin were characterized by the following techniques: laser granulometry, plasticity index by Atterberg limits, X-ray fluorescence, X-ray diffraction, mineralogical composition by Rietveld, thermogravimetric and differential thermal analysis. To study the formulations, specifically for evaluation of technological properties of the parts, was performed an experimental model that combined planning involving a mixture of three components (standard mass x phyllite x kaolin waste) and a 23 factorial design with central point associated with thermal processing parameters. The experiment was performed with restricted strip-plot randomization. In total, 13 compositional points were investigated within the following constraints: phyllite ≤ 20% by weight, kaolin waste ≤ 40% by weight, and standard mass ≥ 60% by weight. The thermal parameters were used at the following levels: 750 and 950 °C to the firing temperature, 5 and 15 °C/min at the heating rate, 15 and 45min to the baseline. The results showed that the introduction of phyllite and/or kaolin waste in ceramic body produced a number of benefits in properties of the final product, such as: decreased absorption of water, apparent porosity and linear retraction at burn; besides the increase in apparent specific mass and mechanical properties of parts. The best results were obtained in the compositional points where the sum of the levels of kaolin waste and phyllite was maximal (40% by weight), as well as conditions which were used in firing temperatures of 950 °C. Regarding the prospect of savings in heat energy required to form the desired microstructure, the phyllite and the residue of kaolin, for having small particle sizes and constitutions mineralogical phases with the presence of fluxes, contributed to the optimization of the firing cycle.