Planning accelerated life tests under Exponentiated-Weibull-Arrhenius model

Purpose - The purpose of this paper is to present designs for an accelerated life test (ALT). Design/methodology/approach - Bayesian methods and simulation Monte Carlo Markov Chain (MCMC) methods were used. Findings - In the paper a Bayesian method based on MCMC for ALT under EW distribution (for life time) and Arrhenius models (relating the stress variable and parameters) was proposed. The paper can conclude that it is a reasonable alternative to the classical statistical methods since the implementation of the proposed method is simple, not requiring advanced computational understanding and inferences on the parameters can be made easily. By the predictive density of a future observation, a procedure was developed to plan ALT and also to verify if the conformance fraction of the manufactured process reaches some desired level of quality. This procedure is useful for statistical process control in many industrial applications. Research limitations/implications - The results may be applied in a semiconductor manufacturer. Originality/value - The Exponentiated-Weibull-Arrhenius model has never before been used to plan an ALT. © Emerald Group Publishing Limited.

Classification of lumber of Eucalyptus using non-destructive tests

Classification and standardization of the sawn wood is a usual activity, developed by countries that come as great consumers of this material. Brazil does not practice the classification of sawn wood. This work had the main objective of evaluating the sensibility of most common non-destructive tests in the classification of dimension lumber from fast grown Eucalyptus plantation. Wood was obtained from genetic material cultivated at Minas Gerais State, Brazil. 296 beams of structural dimensions (6 cm × 12 cm × 280 cm) from 10 different clones of Eucalyptus were sampled. Beams were non-destructively (stress wave, ultrasound and transverse vibration) and destructively (static bending and compression parallel to grain) tested. Non-destructive results showed sensibility in the classification of structural dimension lumber, being possible to establish wave velocity intervals that attend to the main strength classes reported by Wooden Structures Brazilian Code.

The use of slot filter in piezocone tests for site characterization of tropical soils

The use of piezocone tests with a slot filter filled with automotive grease for site characterization of tropical soils is assessed. Laboratory tests using the slot filter filled with automotive grease as well as the conventional porous piezo-element saturated with glycerin were carried out to evaluate the pore pressure (u 2) transducer response. CPTu tests using piezo-elements saturated with glycerin and the slot filter filled with grease were pushed side by side in different research sites in Brazil. Estimates of mechanical and hydraulic soil parameters were made based on pore pressure dissipation curves from using both techniques. Laboratory test results indicate that the pore pressure response using the slot filter with grease was delayed when compared to the piezo-element saturated with glycerin, since grease has a higher viscosity. For tropical soils, the records of u2 in piezocone tests using slot filter with grease presented larger peaks than with porous element saturated with glycerin. Records of u2 using the slot filter above the groundwater table suggest the increase of the degree of saturation in unsaturated zone, where porous filter can be desaturated by suction. The slot filter can be used to help the interpretation of the soil profile with deep groundwater level as well as to help detecting its position for some studied soils. The results shown high repeatability for all study sites. This technique is much easier to handle, especially for tropical soils, where the groundwater table is usually deep and pre-drilling is expensive and time consuming. © 2009 IOS Press.

Aerobic fitness evaluation during walking tests identifies the maximal lactate steady state

Objective. The aim of this study was to verify the possibility of lactate minimum (LM) determination during a walking test and the validity of such LM protocol on predicting the maximal lactate steady-state (MLSS) intensity. Design. Eleven healthy subjects (24.2 ± 4.5 yr; 74.3 ± 7.7 kg; 176.9 ± 4.1 cm) performed LM tests on a treadmill, consisting of walking at 5.5 km h -1 and with 20-22% of inclination until voluntary exhaustion to induce metabolic acidosis. After 7 minutes of recovery the participants performed an incremental test starting at 7% incline with increments of 2% at each 3 minutes until exhaustion. A polynomial modeling approach (LMp) and a visual inspection (LMv) were used to identify the LM as the exercise intensity associated to the lowest [bLac] during the test. Participants also underwent to 24 constant intensity tests of 30 minutes to determine the MLSS intensity. Results. There were no differences among LMv (12.6 ± 1.7 %), LMp (13.1 ± 1.5 %), and MLSS (13.6 ± 2.1 %) and the Bland and Altman plots evidenced acceptable agreement between them. Conclusion. It was possible to identify the LM during walking tests with intensity imposed by treadmill inclination, and it seemed to be valid on identifying the exercise intensity associated to the MLSS. Copyright © 2012 Guilherme Morais Puga et al.

Entomopathogens isolated from invasive ants and tests of their pathogenicity

Some ant species cause severe ecological and health impact in urban areas. Many attempts have been tested to control such species, although they do not always succeed. Biological control is an alternative to chemical control and has gained great prominence in research, and fungi and nematodes are among the successful organisms controlling insects. This study aimed to clarify some questions regarding the biological control of ants. Invasive ant species in Brazil had their nests evaluated for the presence of entomopathogens. Isolated entomopathogens were later applied in colonies of Monomorium floricola under laboratory conditions to evaluate their effectiveness and the behavior of the ant colonies after treatment. The entomopathogenic nematodes Heterorhabditis sp. and Steinernema sp. and the fungi Beauveria bassiana, Metarhizium anisopliae, and Paecilomyces sp. were isolated from the invasive ant nests. M. floricola colonies treated with Steinernema sp. and Heterorhabditis sp. showed a higher mortality of workers than control. The fungus Beauveria bassiana caused higher mortality of M. floricola workers. However, no colony reduction or elimination was observed in any treatment. The defensive behaviors of ants, such as grooming behavior and colony budding, must be considered when using fungi and nematodes for biological control of ants. Copyright © 2012 Maria Fernanda Miori de Zarzuela et al.

Biosolid soil application: Toxicity tests under laboratory conditions

A large volume of generated sewage sludge makes its disposal a problem. The usage of sludge in agriculture is highlighted by a number of advantages. However, heavy metals and other toxic compounds may exercise harmful effects to soil organisms. This study evaluated the possible toxic effects of a biosolid sample, under laboratory conditions, for 30 days, using diplopods Rhinocricus padbergi and plants Allium cepa (onion) as test organisms. The data obtained demonstrated that the biosolid raw sample had genotoxic potential for Allium cepa root tip cells. In the diplopods exposed to biosolid sample, epithelium disorganization in the midgut and a reduction of the volume of the hepatic cells were observed after 7 days of exposure. After 30 days, the animals still showed a reduction of the volume of the hepatic cells, but in minor intensity. Allium cepa analysis showed genotoxicity, but this effect was reduced after 30 days of bioprocessing by diplopods. This study was important to know the effects as well as to determine how this waste could be applied concerning the soil living organisms and plants. © 2012 Cintya Ap. Christofoletti et al.

Monitoramento temporal da pluma de contaminação no aterro de resíduos urbanos de Rio Claro (SP) por meio do método geofísico da eletrorresistividade

Several factors have contributed to the increase the world production of urban solid waste, resulting in difficulties to the correct management and the final environmentally appropriate disposal, in addition to causing serious socio-economic, environmental, and public health troubles. The soil and groundwater contamination by leachate in waste disposal sites is almost always present, leveraging the emergence and/or adaptation of methodologies for environmental assessment of these areas. The geophysical methods, especially the electrical resistivity method, are fast, reliable and low-cost alternative for this purpose. This paper reports the methodology adopted for the temporal monitoring of the plume of contamination of controlled landfill in the municipality of Rio Claro (SP). Electrical resistivity data were obtained in 1999 and 2008, by the resistivity method, using the techniques of vertical electrical sounding and electrical profile. In both years, similar tests were carried out in the same locations within the disposal area. The results indicated that the plume of contamination has resistivity values less than or equal to 50 ohm.m and moves guided by 2 flows: the main, to the southeast, and the secondary, to the west. Relatively to the first series of tests in 1999, the plume of contamination was higher and deeper in 2008, contrary to what was expected for a landfill deactivated for at least 10 years.

Effect of seating forces on cement-ceramic adhesion in microtensile bond tests

Objectives: The aim of this study was to evaluate the effect of different seating forces during cementation in cement-ceramic microtensile bond strength (μTBS). Materials and methods: Forty-five blocks (5 × 5 × 4 mm3) of a glass-infiltrated alumina-based ceramic (In-Ceram Alumina) were fabricated according to the manufacturer's instructions and duplicated in resin composite. Ceramic surfaces were polished, cleaned for 10 min in an ultrasonic bath, silica coated using a laboratory type of air abrasion device, and silanized. Each treated ceramic block was then randomly assigned to five groups (n = 9) and cemented to a composite block under five seating forces (10 g, 50 g, 100 g, 500 g, and 750 g) using a dual-cured resin cement (Panavia F). The ceramic-cement-composite assemblies were cut under coolant water to obtain bar specimens (1 mm × 0. 8 mm2). The μTBS tests were performed in a universal testing machine (1 mm/min). The mean bond strengths values were statistically analyzed using one-way ANOVA (α ≤ 0. 05). Results: Different seating forces resulted in no significant difference in the μTBS results ranging between 13. 1 ± 4. 7 and 18. 8 ± 2. 1 MPa (p = 0. 13) and no significant differences among cement thickness. Conclusions: Excessive seating forces during cementation seem not to affect the μTBS results. Clinical relevance: Excessive forces during the seating of single all-ceramic restorations cementation seem to display the same tensile bond strength to the resin cement. © 2012 Springer-Verlag.

The seismic SPT to determine the maximum shear modulus

This paper presents the first results of a system to carry out seismic SPT, which associates the up-hole seismic technique to the currently used SPT test. This hybrid test allows determining the maximum shear modulus (G 0) together with the SPT test. G 0 is the most important dynamic soil parameter and it is calculated based on the shear wave velocity (V S) measurements. The equipment and the method of analysis will be briefly described. The V s values measured using the S-SPT in one experimental research site located inland of Sao Paulo State-Brazil are presented and compared with down-hole and Seismic CPT test data. These preliminary results indicate that the S-SPT was satisfactory and can be used for dynamic site characterization.

The use of CPT to evaluate the effect of helical pile installation in tropical soils

The uplift capacity of helical piles depends on the shear resistance of the soil above the helical plates. During helical pile installation, the soil traversed by the plates are sheared and displaced laterally, and consequently the soil structure is disturbed. Considering this fact, the aim of this paper is presenting the effect of helical piles installation in the soil mass by means of CPT tests carried out close to the soil cylinder above the pile helices. The CPT tests were performed at the CRHEA site from the Sao Carlos School of Engineering, Sao Carlos city, inland of Sao Paulo State, Brazil. In addition, an interpretation of CPT tests data for stratigrafic logging are presented and compared to Standard Penetration Tests (SPT) carried out at this site. This study showed that the CPT sleeve friction fs data were affected by the installation of helical pile in this particular tropical soil site. © 2013 Taylor & Francis Group.

Longitudinal analysis of serological tests officially adopted by the Brazilian Ministry of Health for the diagnosis of canine visceral leishmaniasis in dogs vaccinated with Leishmune®

Development of vaccines against canine visceral leishmaniasis (CVL) may provide a prophylactic barrier, but antibody response detected by standard diagnostic techniques may not separate vaccinated from naturally infected dogs. Moreover, anti-Leishmania antibody levels in vaccinated dogs may be detectable for months. Accordingly, the aim of the present study was to comparatively evaluate an in-house ELISA with three serological tests officially adopted by the Brazilian Ministry of Health for the diagnosis of CVL in dogs vaccinated with Leishmune®. A total of 18 mongrel dogs were submitted to a complete protocol of the vaccine, monitored and evaluated in 5 times (T0-T4) up to 180 days after T0. Twenty-one days after the first dose (T1), 50% of the dogs were seropositive by the in-house ELISA and 5.5% by IFAT, while by the official ELISA and DPP® CVL rapid test all dogs tested negative. At time T2, 42 days after of the first dose, 100%, 83.3%, 11.1%, and 5.5% of the dogs were seropositive by the in-house ELISA, IFAT, official ELISA kit and the DPP® CVL rapid test, respectively. Ninety days after the first dose (T3), 100%, 83.3%, 72.2% and 33.3% of the dogs were seropositive by the in-house ELISA, official ELISA kit, IFAT, and the DPP® CVL rapid test, respectively. Finally, at time T4, 88.8%, 33.3%, 11.1% and 5.5% of the dogs were seropositive by the in-house ELISA, official ELISA kit, DPP® CVL rapid test and IFAT, respectively. In conclusion, dogs vaccinated with Leishmune® cross-react by an in-house ELISA and by the three official Brazilian serological tests for the diagnosis of canine visceral leishmaniasis up to six months after the first vaccine dose, and may be mistakenly diagnosed and removed. © 2013 Elsevier B.V.

Parametric VaR with goodness-of-fit tests based on EDF statistics for extreme returns

Parametric VaR (Value-at-Risk) is widely used due to its simplicity and easy calculation. However, the normality assumption, often used in the estimation of the parametric VaR, does not provide satisfactory estimates for risk exposure. Therefore, this study suggests a method for computing the parametric VaR based on goodness-of-fit tests using the empirical distribution function (EDF) for extreme returns, and compares the feasibility of this method for the banking sector in an emerging market and in a developed one. The paper also discusses possible theoretical contributions in related fields like enterprise risk management (ERM). © 2013 Elsevier Ltd.

Estudo hidrofaciológico do aqüífero Rio Claro no município de Rio Claro - SP

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

DesG: uma nova metodologia para intervenção e coleta de dados magnetotelúricos

Esta tese apresenta duas contribuições para a interpretação geofísica, voltadas ao Método Magnetotelúrico. A primeira trata de uma nova abordagem para a interpretação MT, denominada MÉTODO DESCRITIVO-GEOLÓGICO (DesG), em alusão à incorporação explícita de informação a priori de correlação fácil com a descrição geológica tradicional. O intérprete define por meio de elementos geométricos (pontos e linhas) o arcabouço de feições geológicas bem como fornece valores de resistividade aos corpos geológicos presumidos. O método estima a distribuição de resistividade subsuperficial em termos de fontes anômalas próximas aos elementos geométricos, ajustando as respostas produzidas por estes corpos às medidas de campo. A solução obtida fornece então informações que podem auxiliar na modificação de algumas informações a priori imprecisas, permitindo que sucessivas inversões sejam realizadas até que a solução ajuste os dados e faça sentido geológico. Entre as características relevantes do método destacam-se: (i) os corpos podem apresentar resistividade maior ou menor do que a resistividade do meio encaixante, (ii) vários meios encaixantes contendo ou não corpos anômalos podem ser cortados pelo perfil e (iii) o contraste de resistividade entre corpo e encaixante pode ser abrupto ou gradativo. A aplicação do método a dados sintéticos evidencia, entre outras vantagens, a sua potencialidade para estimar o mergulho de falhas com inclinação variável, que merece especial interesse em Tectônica, e delinear soleiras de diabásio em bacias sedimentares, um sério problema para a prospecção de petróleo. O método permite ainda a interpretação conjunta das causas do efeito estático e das fontes de interesse. A aplicação a dados reais é ilustrada tomando-se como exemplo dados do COPROD2, cuja inversão produziu soluções compatíveis com o conhecimento geológico sobre a área. A segunda contribuição refere-se a desenho de experimento geofísico. Por meio de indicadores diversos, em especial a matriz densidade de informação, é mostrado que a resolução teórica dos dados pode ser estudada, que guia o planejamento da prospecção. A otimização do levantamento permite determinar os períodos e as posições das estações de medida mais adequados ao delineamento mais preciso de corpos cujas localizações são conhecidas aproximadamente.