Análise de causas de trincas em carro de translação de empilhadeira/recuperadora

The present work aims to study the possible causes of cracks founded and recovered in translation cars of ore Forklift / ore Reclaimer. To identify the possible causes of cracks observed on the equipment it was used a static approach analysis, using a finite element method as an analysis tool, using a specific structural analysis program. After making the model, a strain gage measurement was necessary because there may be significant amounts of masses of non-structural components that were not modeled and were not available in the drawings, as well as fouling ore. With the calibrated model it was processed analyses with the load cases of dead load, product, wind and excavation. After the processing, it was observed that none of these load cases resulted in values that caused the crack, so another three hypotheses were tested: depression and misalignment, jacking and translation of only three cars. Of these three hypotheses it was observed that the jacking coud be the cause of the cracks, because the distribution of stress. Due to the miss of parameters, like the height utilized in this process, it was not possible to affirm the real stress level

Sistema de adquisición de datos compacto para medidas de extensiometría y posición

En este proyecto se trata el diseño y construcción de un sistema de adquisición de datos compacto y de bajo coste para medidas de extensiometría y posición. Dicho sistema irá embarcado en una bicicleta de montaña con el fin de medir determinados parámetros. Estos parámetros son a) Elongación de las suspensiones, b) Deformación en el cuadro. Para la medida de elongación de las suspensiones se diseña y construye un sensor casero de bajo coste basado en una transparencia y un par de diodos fotoemisor y fotorreceptor infrarrojos. Se imprime un gradiente y se emplean dos tubos coaxiales de PVC. La medida de extensiometría se realiza con galgas extensiométricas, puentes de Wheatstone y amplificador de instrumentación. Las muestras se digitalizan con el ADC del microcontrolador C8051F020 de la casa Silabs, que se usa en una placa de desarrollo, y se almacenan en una memoria flash serie. Se desarrolla un software para PC con LabView para poder recibir, procesar y visualizar las muestras obtenidas de los distintos canales con el fin de analizarlas. Se obtienen conclusiones de los resultados de pruebas básicas. ABSTRACT On this project, the design and construction of a compact, low cost, data adquisition system for strain and position measurements is dealt with. Such system will be embedded on a bicycle in order to measure certain parameters. These are a) Suspension elongation, b) Frame deformation. For suspension elongation measurements, a homemade, low cost sensor based on a photoemitter-photoreceiver diode couple and a transparent sheet is designed and built. A gradient is printed in the transparent sheet, and two coaxial PVC pipes are used. Strain measurements are carried out by means of a strain gage, Wheatstone bridges and an instrumentation amplifier. Samples are digitized with Silabs’ C8051F020’s ADC, which is used in a development board, and are stored in a serial flash memory. Software for PC on LabView is developed in order to receive, process and visualize the obtained samples from each channel in order to analyze them. Results are obtained from basic tests.

Análise numérica e experimental de juntas aeronáuticas rebitadas sob solicitação estática.

Uniões por prendedores são elementos amplamente utilizados na indústria aeronáutica para a união de partes constituintes da aeronave. Contudo, devido à sua geometria e aos carregamentos sofridos, estes elementos estão frequentemente sujeitos a falhas por fadiga. Assim, para um projeto e dimensionamento bem executado dessas juntas, é necessário conhecer seu comportamento mecânico e o campo de tensões ao qual estão sujeitas. O método dos elementos finitos certamente atende a estas necessidades; porém, o uso de elementos sólidos tridimensionais para a representação destas uniões pode levar a análises demasiadamente demoradas e custosas, sendo desejável o uso de modelos mais simplificados. Nesse trabalho, juntas de topo assimétricas são modeladas pelo método dos elementos finitos, utilizando tanto elementos sólidos tridimensionais quanto elementos de casca, com o objetivo de encontrar um modelo relativamente simples que apresente resultados satisfatórios e requeira um menor tempo de solução. Os resultados numéricos obtidos são comparados com resultados experimentais, que utilizam extensômetros e fotoelasticidade.

Study of carbon nanotube film and shape memory alloys treatment for sensing and structural vibration control

Structural vibration control is of great importance. Current active and passive vibration control strategies usually employ individual elements to fulfill this task, such as viscoelastic patches for providing damping, transducers for picking up signals and actuators for inputting actuating forces. The goal of this dissertation work is to design, manufacture, investigate and apply a new type of multifunctional composite material for structural vibration control. This new composite, which is based on multi-walled carbon nanotube (MWCNT) film, is potentially to function as free layer damping treatment and strain sensor simultaneously. That is, the new material integrates the transducer and the damping patch into one element. The multifunctional composite was prepared by sandwiching the MWCNT film between two adhesive layers. Static sensing test indicated that the MWCNT film sensor resistance changes almost linearly with the applied load. Sensor sensitivity factors were comparable to those of the foil strain gauges. Dynamic test indicated that the MWCNT film sensor can outperform the foil strain gage in high frequency ranges. Temperature test indicated the MWCNT sensor had good temperature stability over the range of 237 K-363 K. The Young’s modulus and shear modulus of the MWCNT film composite were acquired by nanoindentation test and direct shear test, respectively. A free vibration damping test indicated that the MWCNT composite sensor can also provide good damping without adding excessive weight to the base structure. A new model for sandwich structural vibration control was then proposed. In this new configuration, a cantilever beam covered with MWCNT composite on top and one layer of shape memory alloy (SMA) on the bottom was used to illustrate this concept. The MWCNT composite simultaneously serves as free layer damping and strain sensor, and the SMA acts as actuator. Simple on-off controller was designed for controlling the temperature of the SMA so as to control the SMA recovery stress as input and the system stiffness. Both free and forced vibrations were analyzed. Simulation work showed that this new configuration for sandwich structural vibration control was successful especially for low frequency system.

Non-contact test set-up for aeroelasticity in a rotating turbomachine combining a novel acoustic excitation system with tip-timing

Due to trends in aero-design, aeroelasticity becomes increasingly important in modern turbomachines. Design requirements of turbomachines lead to the development of high aspect ratio blades and blade integral disc designs (blisks), which are especially prone to complex modes of vibration. Therefore, experimental investigations yielding high quality data are required for improving the understanding of aeroelastic effects in turbomachines. One possibility to achieve high quality data is to excite and measure blade vibrations in turbomachines. The major requirement for blade excitation and blade vibration measurements is to minimize interference with the aeroelastic effects to be investigated. Thus in this paper, a non-contact-and thus low interference-experimental set-up for exciting and measuring blade vibrations is proposed and shown to work. A novel acoustic system excites rotor blade vibrations, which are measured with an optical tip-timing system. By performing measurements in an axial compressor, the potential of the acoustic excitation method for investigating aeroelastic effects is explored. The basic principle of this method is described and proven through the analysis of blade responses at different acoustic excitation frequencies and at different rotational speeds. To verify the accuracy of the tip-timing system, amplitudes measured by tip-timing are compared with strain gage measurements. They are found to agree well. Two approaches to vary the nodal diameter (ND) of the excited vibration mode by controlling the acoustic excitation are presented. By combining the different excitable acoustic modes with a phase-lag control, each ND of the investigated 30 blade rotor can be excited individually. This feature of the present acoustic excitation system is of great benefit to aeroelastic investigations and represents one of the main advantages over other excitation methods proposed in the past. In future studies, the acoustic excitation method will be used to investigate aeroelastic effects in high-speed turbomachines in detail. The results of these investigations are to be used to improve the aeroelastic design of modern turbomachines.

Multifunctional cement composites strain and damage sensors applied on reinforced concrete (RC) structural elements

In this research, strain-sensing and damage-sensing functional properties of cement composites have been studied on a conventional reinforced concrete (RC) beam. Carbon nanofiber (CNFCC) and fiber (CFCC) cement composites were used as sensors on a 4 m long RC beam. Different casting conditions (in situ or attached), service location (under tension or compression) and electrical contacts (embedded or superficial) were compared. Both CNFCC and CFCC were suitable as strain sensors in reversible (elastic) sensing condition testing. CNFCC showed higher sensitivities (gage factor up to 191.8), while CFCC only reached gage factors values of 178.9 (tension) or 49.5 (compression). Furthermore, damage-sensing tests were run, increasing the applied load progressively up to the RC beam failure. In these conditions, CNFCC sensors were also strain sensitive, but no damage sensing mechanism was detected for the strain levels achieved during the tests. Hence, these cement composites could act as strain sensors, even for severe damaged structures near to their collapse.

Strain and damage sensing properties on multifunctional cement composites with CNF admixture

Both strain and damage sensing properties on carbon nanofiber cement composites (CNFCC) are reported in the present paper. Strain sensing tests were first made on the material’s elastic range. The applied loading levels have been previously calculated from mechanical strength tests. The effect of several variables on the strain-sensing function was studied, e.g. cement pastes curing age, current density, loading rate or maximum stress applied. All these parameters were discussed using the gage factor as reference. After this first set of elastic experiments, the same specimens were gradually loaded until material’s failure. At the same time both strain and resistivity were measured. The former was controlled using strain gages, and the latter using a multimeter on a four probe setup. The aim of these tests was to prove the sensitivity of these CNF composites to sense their own damage, i.e. check the possibility of fabricating structural damage sensors with CNFCC’s. All samples with different CNF dosages showed good strain-sensing capacities for curing periods of 28 days. Furthermore, a 2%CNF reinforced cement paste has been sensitive to its own structural damage.

Genome Sequence Of Streptomyces Wadayamensis Strain A23, An Endophytic Actinobacterium From Citrus Reticulata.

The actinobacterium Streptomyces wadayamensis A23 is an endophyte of Citrus reticulata that produces the antimycin and mannopeptimycin antibiotics, among others. The strain has the capability to inhibit Xylella fastidiosa growth. The draft genome of S. wadayamensis A23 has ~7.0 Mb and 6,006 protein-coding sequences, with a 73.5% G+C content.

Draft Genome Sequence Of Ft9, A Novel Bacillus Cereus Strain Isolated From A Brazilian Thermal Spring.

A Bacillus cereus strain, FT9, isolated from a hot spring in the midwest region of Brazil, had its entire genome sequenced.

Strain Gauges's Analysis On Implant-retained Prosthesis' Cast Accuracy.

A proper cast is essential for a successful rehabilitation with implant prostheses, in order to produce better structures and induce less strain on the implants. The aim of this study was to evaluate the precision of four different mold filling techniques and verify an accurate methodology to evaluate these techniques. A total of 40 casts were obtained from a metallic matrix simulating three unit implant-retained prostheses. The molds were filled using four different techniques in four groups (n = 10): Group 1 - Single-portion filling technique; Group 2 - Two-step filling technique; Group 3 - Latex cylinder technique; Group 4 - Joining the implant analogs previously to the mold filling. A titanium framework was obtained and used as a reference to evaluate the marginal misfit and tension forces in each cast. Vertical misfit was measured with an optical microscope with an increase of 120 times following the single-screw test protocol. Strain was quantified using strain gauges. Data were analyzed using one-way ANOVA (Tukey's test) (α =0.05). The correlation between strain and vertical misfit was evaluated by Pearson test. The misfit values did not present statistical difference (P = 0.979), while the strain results showed statistical difference between Groups 3 and 4 (P = 0.027). The splinting technique was considered to be as efficient as the conventional technique. The strain gauge methodology was accurate for strain measurements and cast distortion evaluation. There was no correlation between strain and marginal misfit.

Genomic And Chemical Insights Into Biosurfactant Production By The Mangrove-derived Strain Bacillus Safensis Ccma-560.

Many Bacillus species can produce biosurfactant, although most of the studies on lipopeptide production by this genus have been focused on Bacillus subtilis. Surfactants are broadly used in pharmaceutical, food and petroleum industry, and biological surfactant shows some advantages over the chemical surfactants, such as less toxicity, production from renewable, cheaper feedstocks and development of novel recombinant hyperproducer strains. This study is aimed to unveil the biosurfactant metabolic pathway and chemical composition in Bacillus safensis strain CCMA-560. The whole genome of the CCMA-560 strain was previously sequenced, and with the aid of bioinformatics tools, its biosurfactant metabolic pathway was compared to other pathways of closely related species. Fourier transform infrared (FTIR) and high-resolution TOF mass spectrometry (MS) were used to characterize the biosurfactant molecule. B. safensis CCMA-560 metabolic pathway is similar to other Bacillus species; however, some differences in amino acid incorporation were observed, and chemical analyses corroborated the genetic results. The strain CCMA-560 harbours two genes flanked by srfAC and srfAD not present in other Bacillus spp., which can be involved in the production of the analogue gramicidin. FTIR and MS showed that B. safensis CCMA-560 produces a mixture of at least four lipopeptides with seven amino acids incorporated and a fatty acid chain with 14 carbons, which makes this molecule similar to the biosurfactant of Bacillus pumilus, namely, pumilacidin. This is the first report on the biosurfactant production by B. safensis, encompassing the investigation of the metabolic pathway and chemical characterization of the biosurfactant molecule.

Influence Of The Major Nitrite Transporter Nirc On The Virulence Of A Swollen Head Syndrome Avian Pathogenic E. Coli (apec) Strain.

Avian Pathogenic Escherichia coli (APEC) strains are extra-intestinal E. coli that infect poultry and cause diseases. Nitrite is a central branch-point in bacterial nitrogen metabolism and is used as a cytotoxin by macrophages. Unlike nitric oxide (NO), nitrite cannot diffuse across bacterial membrane cells. The NirC protein acts as a specific channel to facilitate the transport of nitrite into Salmonella and E. coli cells for nitrogen metabolism and cytoplasmic detoxification. NirC is also required for the pathogenicity of Salmonella by downregulating the production of NO by the host macrophages. Based on an in vitro microarray that revealed the overexpression of the nirC gene in APEC strain SCI-07, we constructed a nirC-deficient SCI-07 strain (ΔnirC) and evaluated its virulence potential using in vivo and in vitro assays. The final cumulative mortalities caused by mutant and wild-type (WT) were similar; while the ΔnirC caused a gradual increase in the mortality rate during the seven days recorded, the WT caused mortality up to 24h post-infection (hpi). Counts of the ΔnirC cells in the spleen, lung and liver were higher than those of the WT after 48 hpi but similar at 24 hpi. Although similar number of ΔnirC and WT cells was observed in macrophages at 3 hpi, there was higher number of ΔnirC cells at 16 hpi. The cell adhesion ability of the ΔnirC strain was about half the WT level in the presence and absence of alpha-D-mannopyranoside. These results indicate that the nirC gene influences the pathogenicity of SCI-07 strain.

Evaluation of DNA extraction protocols for Brucella abortus pcr detection in aborted fetuses or calves born from cows experimentally infected with strain 2308

The objective of the present study was to improve the detection of B. abortus by PCR in organs of aborted fetuses from infected cows, an important mechanism to find infected herds on the eradication phase of the program. So, different DNA extraction protocols were compared, focusing the PCR detection of B. abortus in clinical samples collected from aborted fetuses or calves born from cows challenged with the 2308 B. abortus strain. Therefore, two gold standard groups were built based on classical bacteriology, formed from: 32 lungs (17 positives), 26 spleens (11 positives), 23 livers (8 positives) and 22 bronchial lymph nodes (7 positives). All samples were submitted to three DNA extraction protocols, followed by the same amplification process with the primers B4 and B5. From the accumulated results for organ, the proportion of positives for the lungs was higher than the livers (p=0.04) or bronchial lymph nodes (p=0.004) and equal to the spleens (p=0.18). From the accumulated results for DNA extraction protocol, the proportion of positives for the Boom protocol was bigger than the PK (p<0.0001) and GT (p=0.0004). There was no difference between the PK and GT protocols (p=0.5). Some positive samples from the classical bacteriology were negative to the PCR and viceversa. Therefore, the best strategy for B. abortus detection in the organs of aborted fetuses or calves born from infected cows is the use, in parallel, of isolation by classical bacteriology and the PCR, with the DNA extraction performed by the Boom protocol.

Experimental infection of dogs with a Brazilian strain of Rickettsia rickettsii: clinical and laboratory findings

The bacterium Rickettsia rickettsii is the etiological agent of an acute, severe disease called Rocky Mountain spotted fever in the United States or Brazilian spotted fever (BSF) in Brazil. In addition to these two countries, the disease has also been reported to affect humans in Mexico, Costa Rica, Panama, Colombia and Argentina. Like humans, dogs are also susceptible to R. rickettsii infection. However, despite the wide distribution of R. rickettsii in the Western Hemisphere, reports of R. rickettsii-induced illness in dogs has been restricted to the United States. The present study evaluated the pathogenicity for dogs of a South American strain of R. rickettsii. Three groups of dogs were evaluated: group 1 (G1) was inoculated ip with R. rickettsii; group 2 (G2) was infested by R. rickettsii-infected ticks; and the control group (G3) was infested by uninfected ticks. During the study, no clinical abnormalities, Rickettsia DNA or R. rickettsii-reactive antibodies were detected in G3. In contrast, all G1 and G2 dogs developed signs of rickettsial infection, i.e., fever, lethargy, anorexia, ocular lesions, thrombocytopenia, anemia and detectable levels of Rickettsia DNA and R. rickettsii-reactive antibodies in their blood. Rickettsemia started 3-8 days after inoculation or tick infestation and lasted for 3-13 days. Our results indicate that a Brazilian strain of R. rickettsii is pathogenic for dogs, suggesting that canine clinical illness due to R. rickettsii has been unreported in Brazil and possibly in the other South American countries where BSF has been reported among humans.