Reliability of timber bridges using nailed plywood box beams

The Nailed Box Beam structural efficiency is directly dependent of the flange-web joint behavior, which determines the partial composition of the section, as the displacement between elements reduces the effective rigidity of the section and changes the stress distribution and the total displacement of the section. This work discusses the use of Nailed Plywood Box Beams in small span timber bridges, focusing on the reliability of the beam element. It is presented the results of tests carried out in 21 full scale Nailed Plywood Box Beams. The analysis of maximum load tests results shows that it presents a normal distribution, permitting the characteristic values calculation as the normal distribution theory specifies. The reliability of those elements was analyzed focusing on a timber bridge design, to estimate the failure probability in function of the load level.

Desenvolvimento das técnicas de produção de blocos de concreto para alvenaria estrutural na escala (1:4)

Pós-graduação em Engenharia Civil - FEIS

Avaliação da auto-suficiência energética de reatores anaeróbios no tratamento de esgoto sanitário e de água preta

The purpose of this project is to verify whether anaerobic reactors applied to sewage treatment are energetically self-sufficient. This evaluation can be made by balancing the methane produced through the anaerobic transformation stages (hydrolysis, acidogenesis, acetogenesis and methanogenesis) and the reactor energy consumption requirements. The original project included methanogenic activity tests, which could not be performed due to setbacks in the installation of an analytical instrument. Scientific articles about bench- and full-scale anaerobic reactors were investigated instead. An average substrate-to-methane conversion efficiency of 58,2±18,6% was found for the bench-scale reactors and higher efficiencies (89,2%) were found for the cases which had higher Organic Loading Rates (OLRs) values. The average energy output was 0,013 kWh/Lsewage, value unable to meet the energy needs for the reactor operation, considering equipments normally used such as temperature controller. This balance can become positive if few hypotheses are made, for example (i) to eliminate the use of temperature controller (ii) to alter the operation pattern from continuous to intermittent. Based on energy balance assessment of eight bench-scale reactors, it was observed that the implementation of a system for biogas utilization is not energetically feasible. However, interesting results were found for a full-scale sewage treatment plant, ETE Ouro Verde – Foz do Iguaçu, PR, Brazil. Even though its substrate-tomethane conversion efficiency was about 10% only, the energy balance was quite positive, with energy consumption of 68 kWh/month and energy production of 660 kWh/month. This analysis leads us to conclude that energy recovery from full-scale sewage treatment plants should be practiced by other plants

Estudo de dormentes de aço sob solicitações verticais, longitudinais e transversais em via permanente ferroviária

This article presents the results of research conducted on full-scale models, studying the behavior of steel sleepers under the action of static loads, in vertical, longitudinal and transverse directions. For the research models were run with rails TR-68, fixed with elastic system on seven sleepers each type, separately, embedded in standard ballast with 35 cm height and on the basis of compacted soil with 30 cm thick. For the load tests were constructed using reaction systems of vertical and horizontal forces with the objective of applying the requests. The system of readings and data acquisition was fully computerized, obtaining in real time the values of forces and displacements. The results were compared with those installed in the same way with sleepers of wood, mono-block and bi-block prestressed concrete. The analyzed results provided unprecedented parameters in Brazil and of great importance for the design of modern railway permanent way, using steel sleepers.

A low-voltage low-power analog memory cell with built-in 4-quadrant multiplication

An accurate switched-current (SI) memory cell and suitable for low-voltage low-power (LVLP) applications is proposed. Information is memorized as the gate-voltage of the input transistor, in a tunable gain-boosting triode-transconductor. Additionally, four-quadrant multiplication between the input voltage to the transconductor regulation-amplifier (X-operand) and the stored voltage (Y-operand) is provided. A simplified 2 x 2-memory array was prototyped according to a standard 0.8 mum n-well CMOS process and 1.8-V supply. Measured current-reproduction error is less than 0.26% for 0.25 muA less than or equal to I-SAMPLE less than or equal to 0.75 muA. Standby consumption is 6.75 muW per cell @I-SAMPLE = 0.75 muA. At room temperature, leakage-rate is 1.56 nA/ms. Four-quadrant multiplier (4QM) full-scale operands are 2x(max) = 320 mV(pp) and 2y(max). = 448 mV(pp), yielding a maximum output swing of 0.9 muA(pp). 4QM worst-case nonlinearity is 7.9%.

An accurate low-voltage analog memory-cell with built-in multiplication

A CMOS memory-cell for dynamic storage of analog data and suitable for LVLP applications is proposed. Information is memorized as the gate-voltage of input-transistor of a gain-boosting triode-transconductor. The enhanced output-resistance improves accuracy on reading out the sampled currents. Additionally, a four-quadrant multiplication between the input to regulation-amplifier of the transconductor and the stored voltage is provided. Designing complies with a low-voltage 1.2μm N-well CMOS fabrication process. For a 1.3V-supply, CCELL=3.6pF and sampling interval is 0.25μA≤ ISAMPLE ≤ 0.75μA. The specified retention time is 1.28ms and corresponds to a charge-variation of 1% due to junction leakage @75°C. A range of MR simulations confirm circuit performance. Absolute read-out error is below O.40% while the four-quadrant multiplier nonlinearity, at full-scale is 8.2%. Maximum stand-by consumption is 3.6μW/cell.

A low-voltage triode-MOSFET four-quadrant multiplier with optimized current-efficiency

A low-voltage, low-power four-quadrant analog multiplier with optimized current-efficiency is presented. Its core corresponds to a pseudodifferential cascode, gain-boosting triode-transconductor. According to a low-voltage 1.2μm CMOS n-well process, operand differential-amplitudes are 1.0Vpp and 0.32Vpp for a 1.3V-supply. Common-mode voltages are properly chosen to maximize current-efficiency to 58%. Total quiescent dissipation is 260μW. A range of PSPICE simulation supports theoretical analysis. Excellent linearity is observed on dc characteristic. Assuming a ±0.5% mismatch on (W/L) and VTH THD at full-scale is 0.93% and 1.42%, for output frequencies of 1MHz and 10MHz, respectively.

Fatores operacionais e cinética do processo fermentativo para otimização da produção de etanol em escala industrial

Pós-graduação em Microbiologia Agropecuária - FCAV

Protótipo de sistema automotor para cadeira de rodas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação em escala real da formação de THMs em águas de abastecimento

Pós-graduação em Engenharia Civil - FEIS

Avaliação da qualidade de águas pluviais armazenadas e estudos de tratabilidade empregando filtro de pressão com diferentes meios filtrantes visando ao aproveitamento para fins não potáveis

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Alignment of the CMS tracker with LHC and cosmic ray data

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação da auto-suficiência energética de reatores anaeróbios no tratamento de esgoto sanitário e água cinza

The anaerobic treatment of sewage is widely employed in Brazil and it is an appreciated way for the treatment of effluents, helping to reduce the environmental impact in rivers. The methane gas obtained from the process can be applied to improve the energetic efficiency of the system, reducing the amount of waste and the cost of the treatment process. This work presents the net energy balance of anaerobic reactors applied to the treatment of sewage. The analysis was performed considering full-scale and laboratory-scale treatment systems. In laboratory scale, the results from three kinds of systems were compared regarding the biological treatment of greywater. Two of them (UASB7 and UASB12) were anaerobic and the other one was a combined anaerobic-aerobic system (UASB7/SBR6). Greywater methanization (compared to theoretical maximum) was calculated considering 100% removal (g BOD/day), the literature percentage removal and the anionic surfactant presence in the effluentt. For each of these three cases, the efficiencies were, respectively, 16.9%, 43.6% and 51.3% in UASB7 reactor, 25.6%, 50.3% and 59.2% in UASB12 reactor and 30.6%, 61.2% and 71.9% in UASB7/SBR6 reactor. The energetic potential was found to be 4.66x10-4, 7.77x10-4 and 5.12x10-4 kWh/L for the UASB7, UASB12 and UASB7/SBR6 reactors, respectively. The pumping system, the aeration (in the anaerobic-aerobic system) and the temperature controlled heating system were considered to calculate the energetic consumption. However, the third one was not employed since tropical regions like Brazil do not need heating systems and also because of its high energetic consumption. The calculated net energy balance in the reactors was negative in the case of greywater, respectively -0.16, -0.28 and -0.18 kWh/L for the reactors UASB7, UASB12 and UASB7/SRB6. In full scale (ETE Jardim das Flores - Rio Claro, SP), the average energy... (Complete abstract click electronic access below)

Analysis of a microbial community associated with polychlorinated biphenyl degradation in anaerobic batch reactors

The degradation of polychlorinated biphenyls (PCBs) was investigated under fermentativemethanogenic conditions for up to 60 days in the presence of anaerobic biomass from a full-scale UASB reactor. The low methane yields in the PCBs-spiked batch reactors suggested that the biomass had an inhibitory effect on the methanogenic community. Reactors containing PCBs and co-substrates (ethanol/ sodium formate) exhibited substantial PCB reductions from 0.7 to 0.2 mg mL-1 . For the Bacteria domain, the PCBs-spiked reactors were grouped with the PCB-free reactors with a similarity of 55 %, which suggested the selection of a specific population in the presence of PCBs. Three genera of bacteria were found exclusively in the PCB-spiked reactors and were identified using pyrosequencing analysis, Sedimentibacter, Tissierela and Fusibacter. Interestingly, the Sedimentibacter, which was previously correlated with the reductive dechlorination of PCBs, had the highest relative abundance in the RCS-PCB (7.4 %) and RCS-PCB-PF (12.4 %) reactors. Thus, the anaerobic sludge from the UASB reactor contains bacteria from the Firmicutes phylum that are capable of degrading PCBs.

Avaliação da construção e operação de técnicas compensatórias de drenagem urbana: o transporte de finos, a capacidade de infiltração, a taxa de infiltração real do solo e a permeabilidade da manta geotêxtil

This work aimed to evaluate some aspects of construction and operation of full-scale best management practices and their effects on infiltration loading rate. Two systems were studied: i) filter-swale-trench (FST) and ii) infiltration well (IW). In these units, field essays and full-scale measurements were made in order to assess the soil permeability. Further, the fine particles transportation and the geotextile blanket permeability were determined before and after operation. The results pointed out that there were soil transportation to inside the FST and IW systems, despite of the installed protections, and that these material were responsible for diminishing the geotextile (reduction from 30 to 90% for FST and 40 to 70% for IW) and the full-scale infiltration loading rates (varying from 4,7 x 10-6 to 10-5 m.s-1).