Top PDF Precise temperature calibration for laser heat treatment

Precise temperature calibration for laser heat treatment

Precise temperature calibration for laser heat treatment

A radial symmetrical FDM model was developed to inves- tigate the influence of the distribution of the induction heat sources and the resulting temperature fields on the melting process of the metal alloy. Up to about 8000 single finite el- ements were used to achieve a good spatial resolution and to minimize errors caused by the size of the finite elements itself. The induction heating was not simulated directly. The absorbed heat portion of each element was defined manually taking the FEM results into account. The physical effects of heat transfer by conduction, heat losses by radiation at the free crucible surfaces and melting of the metal alloy were implemented; all other physical effects neglected. To simu- late the effect of melting, the following special variant was chosen: if the temperature of the finite element exceeds the melting temperature, the incoming heat portions during each time step are summed up without increasing the temperature of the element until the melting enthalpy of the material is reached. Then the element is marked as fully molten, the ma- terial parameters are changed and the further increase of the temperature is unblocked.
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EFFECT OF THE HEAT AND SURFACE LASER TREATMENT ON THE CORROSION DEGRADATION OF THE Mg-Al ALLOYS

EFFECT OF THE HEAT AND SURFACE LASER TREATMENT ON THE CORROSION DEGRADATION OF THE Mg-Al ALLOYS

The corrosive agent was a 3% NaCl solution. Resistance to electrochemical corrosion was determined on the ground of registered anodic polarisation curves. For potentiodynamic tests system VoltaLab®PGP201 by Radiometer was used. The measurements were carried out in a three-electrode two- chamber glass electrolyser with a volume of 150 cm 3 , equipped with a water jacket connected to the thermostat of the UH-4 type ensuring a regulation with accuracy of ±0,1°C. The samples as well the investigated electrodes were made from the cast magnesium alloys. Radiometer was used. Saturated calomel electrode (NEK) of KP-113 type served as reference electrode, whereas platinum electrode of PtP−201 type was used as auxiliary electrode. The measurements were performed at the room temperature after 20 minutes from the first contact of the investigated material with the electrolyte, by a potential change rate of 120 mV/min. The surface area of the tested samples of the cast magnesium alloys was equal 0,5 cm 2 . The investigations have been carried out on test pieces of AZ12, AZ91, AZ61, AZ31 magnesium alloys in as-cast and after heat and laser treatment states (Table 2). The chemical composition of the investigated materials is
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Effect of Cu addition and heat treatment self-propagating high temperature synthesis reaction in Al-Ti-C system

Effect of Cu addition and heat treatment self-propagating high temperature synthesis reaction in Al-Ti-C system

The characteristics of the powders used in the present study are listed in tab. I. The green compacts were made from commercial powders of 30 wt. % aluminum, 0, 6wt. % Cu, and titanium and graphite powders at a ratio corresponding to that of stoichiometric of TiC. First, the powders were mixed by dry milling with steel balls for 2h and the blends were pressed into compacted samples. The length of the compact was 65 mm, the width was 10 mm and the thickness was 10 mm. The compacts were pressed at pressures of 100 MPa to give densities of (65 ± 5) % theoretical density, and a small hole was drilled against outside of the compact, and one end of the thermocouple (W-5% Re/W-26Re) of 0.005 inches in diameter (welded under flowing argon atmosphere) was inserted into the hole and the other end was linked to the temperature recorder equipment. The compacts were ignited at one end by laser irradiation using 5 kW CO 2 laser (HJ-4) with a fixed wavelength of 10.6 μm, then
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Effect of heat treatment parameters on the properties of low-alloy cast steel with microadditions of vanadium

Effect of heat treatment parameters on the properties of low-alloy cast steel with microadditions of vanadium

Table 2 gives the results of mechanical tests carried out on the low-alloy cast steel with additions of vanadium and compares them with the results of previous studies made on this cast steel (designated as P1 in Tables 1 and 2) subjected to heat treatment recommended by the respective standard [9].

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HYBRID ONLINE MOBILE LASER SCANNER CALIBRATION THROUGH IMAGE  ALIGNMENT BY MUTUAL INFORMATION

HYBRID ONLINE MOBILE LASER SCANNER CALIBRATION THROUGH IMAGE ALIGNMENT BY MUTUAL INFORMATION

This paper proposes an hybrid online calibration method for a laser scanner mounted on a mobile platform also equipped with an imaging system. The method relies on finding the calibration parameters that best align the acquired points cloud to the images. The quality of this intermodal alignment is measured by Mutual information between image luminance and points reflectance. The main advantage and motivation is ensuring pixel accurate alignment of images and point clouds acquired simultaneously, but it is also much more flexible than traditional laser calibration methods.
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Efeito do tratamento térmico nas modificações térmicas e quimicas das madeiras de carvalho e de castanheiro utilizadas no envelhecimento de aguardentes

Efeito do tratamento térmico nas modificações térmicas e quimicas das madeiras de carvalho e de castanheiro utilizadas no envelhecimento de aguardentes

No presente trabalho são estudados os efeitos da temperatura de vergatura e da frequência do humedecimento durante a primeira fase do tratamento térmico (fase de vergatura) na resposta simultânea, do ponto de vista térmico e químico, de diferentes madeiras (castanheiro português, carvalho americano e carvalho romeno) usadas no envelhecimento de aguardentes vínicas Para a determinação da temperatura da madeira recorreu-se a termopares do tipo K. Os compostos extraíveis da madeira (ácidos fenólicos, aldeídos fenólicos, cumarinas e aldeídos furânicos) foram analisados por HPLC. Os resultados evidenciam que a distribuição da temperatura ao longo da espessura da aduela e a composição química da madeira são influenciadas pela temperatura de vergatura e pela frequência do humedecimento, bem como pela espécie botânica da madeira. É demonstrado que a fase de vergatura é de extrema importância para a qualidade da vasilha não apenas pelo seu impacto nas propriedades físicas e mecânicas da madeira, mas por constituir também uma etapa determinante da composição química da mesma. Keywords: oak; chestnut; cooperage; heat treatment; thermal and chemical modifications
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RADIATION CHEMICAL CONVERSION OF OIL DERIVED FROM OIL-BITUMEN ROCK

RADIATION CHEMICAL CONVERSION OF OIL DERIVED FROM OIL-BITUMEN ROCK

The relatively high radiation resistance of the synthetic oil, recovered from the OBR, in vacuum and air below 50°C is associated with the presence of paraffi ns, polynuclear aromatic hydrocarbons, and resin asphaltene substances in its composition. This makes it possible to use the synthetic oil as a feedstock for manufacturing a waterproof material applicable in radiation fi elds, including the disposal of radioactive waste. The organic matter of the OBR may serve as a promising source material for manufacturing various fuels, lubricating oils, coke, and asphalt. Hydrogen, hydrocarbon gases, and olefi n hydrocarbons can be produced from the synthetic oil by the joint ionizing radiation and heat treatment at consistent values of the temperature and the dose rate.
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Regulation of Heat Exchange across the Hornbill Beak: Functional Similarities with Toucans?

Regulation of Heat Exchange across the Hornbill Beak: Functional Similarities with Toucans?

Our data add to a growing body of literature revealing the importance of the avian beak in ther- moregulation [1–4,6,7,26]. The capacity for non-evaporative heat exchange via the beak appears to be most efficient at air temperatures within ~10°C below body temperature. Beak size in birds is correlated with latitude and air temperature [1]. However, in addition to these we argue that water vapour pressure (and hence the humidity gradient available for evaporative heat loss) in the bird’s habitat, likely gives rise to selection pressure acting on beak size, maxi- mising capacity for radiative and convective heat loss in situations where evaporative cooling is likely to be inefficient. Therefore, we speculate that Allen’s rule [38] may apply to humidity gra- dients and temperature gradients: large appendages should be particularly advantageous to birds as well as mammals inhabiting hot, but also humid climates. Additionally, beak size may be limited in extreme hot environments due to the risk of heat uptake via the highly vascu- larised beak when T a exceeds T b . We argue that the ability of birds to vasoconstrict the beak at
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CREST-Snow Field Experiment: analysis of snowpack properties using multi-frequency microwave remote sensing data

CREST-Snow Field Experiment: analysis of snowpack properties using multi-frequency microwave remote sensing data

sence of their daily field measurements. Meteorological data including solar radiation, air temperature, humidity, wind speed, and precipitation obtained from neighboring Na- tional Weather Service Office were used as an input to SNTHERM to simulate snow grain size, density and snowpack temperature. The simulated snowpack temperature from SNTHERM was compared with observed in-situ snowpack temperature. Simu-

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J. Bras. Patol. Med. Lab.  vol.50 número1

J. Bras. Patol. Med. Lab. vol.50 número1

Introduction: The therapeutic monitoring of lithium, through concentration measurements, is important for individual dose adjustment, as a marker of treatment adherence and to prevent poisoning and side effects. Objectives: Validate and compare two methods – atomic emission and atomic absorption – for the determination of lithium in serum samples. Methodology: Parameters such as speciicity, precision, accuracy, limit of detection (LOD) and linearity were considered. The atomic absorption spectrometer was used, operating in either emission or absorption mode. For the quantitative comparison of 30 serum samples from patients with mood disorder treated with lithium, the results were submitted to Student’s t-test, F-test and Pearson’s correlation. Results: The limit of quantiication (LOQ) was established as 0.05 mEq/l of lithium, and calibration curves were constructed in the range of 0.05-2 mEq/l of lithium, using aqueous standards. Sample preparation time was reduced, what is important in medical laboratory. Conclusion: Both methods were considered satisfactory, precise and accurate and can be adopted for lithium quantiication. In the comparison of quantitative results in lithium-treated patients through statistical tests, no signiicant differences were observed. Therefore the methods for lithium quantiication by lame atomic absorption spectrometry (FAAS) and lame atomic emission spectrometry (FAES) may be considered similar.
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Braz. J. Phys.  vol.33 número2

Braz. J. Phys. vol.33 número2

Ref. [1] discusses how to include both the standard data and the barely known data in the calibration and in the interpolation procedure. New and more precise values of physical quantities used as input data are determined using the information contained in the calibration curve. How- ever, in Ref. [1], the procedure was developed in a two steps process and the difficulty with a singular covariance matrix was solved by using some special algorithms.

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Highly porous geopolymers: effect of the processing route on the reached properties

Highly porous geopolymers: effect of the processing route on the reached properties

The first step in the preparation the geopolymer foams was the preparation of a 15 M KOH solution, which should be used after 24 hours [41]. Then, a solution of potassium-based activators and distilled water was prepared in a mixer (500 rpm, 30 minutes, Ika-Werke Ost Basic, Staufen, Germany), following the oxide molar ratios presented in Table A.5. To this solution, Dolapix CE-64 was added (0.32 wt% on the total weight). Then, MSMK and FA were added at room temperature to the activator solution, stirring at 1000 rpm for 30 minutes, producing suspensions with a solid content ranging from 61 to 71 wt%. The geopolymer precursor suspension was placed in an oven at 80ºC for 20 minutes to initiate the geopolymerization reaction, which is the key to enabling the retention of porous morphology of the wet foam subsequently produced. Thereafter, the suspension was removed from the oven and stirred again while adding dropwise one of the surfactants.
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Effects of heat treatment and storage temperature on the use of açaí drink by nutraceutical and beverage industries

Effects of heat treatment and storage temperature on the use of açaí drink by nutraceutical and beverage industries

This study assesses the storage temperature effect on the anthocyanins of pasteurized and unpasteurized açaí pulp. The data was obtained using a pasteurized and lyophilized pulp (PLP) to evaluate the temperature effect (0, 25, and 40 °C). Part of non-pasteurized frozen pulp (NPP) was pasteurized (NPP-P) at 90 °C for 30 seconds; both pulps were stored at 40 °C. The anthocyanin content reduction in the drink was evaluated from the half-life time (t 1/2 ), activation energy (Ea), temperature quotient (Q10), and the reaction rate constant (k). The t 1/2 of the PLP anthocyanins stored at 40 °C was 1.8 times less than that stored at 25 °C and 15 times less than that stored at 0 °C; therefore, the higher temperatures decreased the stability of anthocyanins. The pasteurization increased the t 1/2 by 6.6 times (10.14 hours for NPP and 67.28 hours for NPP-P). The anthocyanin degradation on NPP-P followed a first order kinetic, while NPP followed a second order kinetic; thus it can be said that the pasteurization process can improve the preservation of anthocyanins in the pulp.
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Differential scanning calorimetry, x-ray diffraction and F-19 nuclear magnetic resonance investigations of the crystallization of InF3-based glasses

Differential scanning calorimetry, x-ray diffraction and F-19 nuclear magnetic resonance investigations of the crystallization of InF3-based glasses

height of the corresponding peak increases. This peak ap- pears as a shoulder for sample ~a! and becomes distinct in curve ~b!. However, some crystal growth takes place during annealing. When the annealing temperature increases, a part of the A crystals are already formed, and the enthalpy re- leased on reheating is lower. This is consistent with the ob- servation ~see Fig. 1! that this first crystallization peak in ~c! is located at a lower temperature, and also less pronounced. In a second step, liquid L 1 which is unstable, also crys- tallizes. There are two possible mechanisms: either only re- maining liquid is involved, according to the equation
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Solutions for Energy Efficient and Sustainable Heating of Ventilation Air: A Review

Solutions for Energy Efficient and Sustainable Heating of Ventilation Air: A Review

A passive ventilation air heating configuration, other than the ones located in a building’s exterior walls, can be situated in a ventilated double window. This technology can be implemented in new, as well as existing buildings [82]. The air intake takes place through the cavity between the window glazings (see Fig. 6 a). On the one hand, the heat lost from the inside through the window returns back to the room by the incoming air flow, the double window serves as a recovery system; on the other hand, solar radiation warms the window components and the incoming air [83]. An experimental study, modeling, and simulation analysis [82- 84] has been carried out by Carlos et al. The effect of solar collection and recuperation functions was analyzed. The authors concluded that a ventilated double window is the most advantageous in a system facing south; however it is suitable for any other facade orientation because heat recovery is the dominant function of a ventilated double window. By changing the window orientation from south to north, the heat gain decreases by 22% in mild Portuguese winter conditions, while decreasing 6% in the case of Munich. The double window application can reduce heat loss due to ventilation by 22% in Portugal and 24% in Munich when facing north, while by 28% and 26% respectively when facing south [83].
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Passive solar system applied in trombe walls Débora Ferreira

Passive solar system applied in trombe walls Débora Ferreira

The second part or current work was devoted to the study of six test models built using cement mortar and an appropriate geometry. One of the models served as a reference, another sample model was tested considering that the main facade will simulate a window, while the remaining models were executed as a main facade using the trombe wall building system. Trombe walls were built with four different materials: cement mortar, cement mortar with octadecane, cement mortar with paraffin. All models have been developed with the ability of the wall to be ventilated. All models were monitored and tested in terms of thermal behaviour. Three of the walls testing samples were tested simultaneously under the same conditions, during four days. The differences between the test ’s layouts are related to the granite wall colour and the ventilation surrounding the models. During the monitoring of the models it was possible to obtain temperature records and thermal conductivity of the main facade elements in 10 to 10 minutes intervals. Also, a direct comparison between the tested models was established.
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COMPUTATIONAL FLUID DYNAMICS (CFD) SIMULATING HEATED AIR FROM WOOD BURNING INSIDE A POULTRIES BARN

COMPUTATIONAL FLUID DYNAMICS (CFD) SIMULATING HEATED AIR FROM WOOD BURNING INSIDE A POULTRIES BARN

Among the environmental and thermal variables, air temperature, relative humidity, thermal radiation and air circulation are the ones that directly affect bird performance, since they are homeothermic animals. Environmental variables can have positive or negative effects on poultry production. For instance, high temperature and high relative humidity inside poultry facilities may restrain productivity (VIGODERIS, 2006; YANAGI JUNIOR et al., 2011; OLIVEIRA et al., 2014). Thus, the need to keep the thermal environment within an optimal production range is evident; however, there are few studies using CFD for mass balance in poultry houses. TINÔCO et al. (2010) made simulations of a poultry facility with mechanical ventilation associated to an evaporative cooling system. The authors developed a CFD model to understand the distribution of air temperature and speed. The results of such study showed a good statistical correlation with experimental data, which allowed the authors associating its use to future structural changes, likewise the results of our study.
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C Metal Matrix Composites using Laser Treatment

C Metal Matrix Composites using Laser Treatment

Wear ridges and ploughs are initiated on the worn surface as a result of the abrasive wear. Wear debris were rooted to the side of the scar thereby creating the particles of both powders. The width and depth of the wear scar are different for each sample and with respect to the laser power. The unmelted B 4 C in the deposit has also affected to the depth of wear thereby improving on the wear properties of the primary alloy. Some unmelted TiC was also observed in the crushed zone and allows the clustering of the Ti6Al4V alloy to be embedded and create a martensitic phase within the scar region. Some cracks of the Ti6Al4V alloy were also found on the scar which was initiated as a result of the unmelted B 4 C during the back and forth of the crusher (tungsten carbide ball).
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Recovery Mechanisms in a Compressed Ni-Ti Superelastic Alloy

Recovery Mechanisms in a Compressed Ni-Ti Superelastic Alloy

These alloys have an interface between a martensitic monoclinic phase (B19') and a high-temperature austenitic phase (B2), positioned in such a way that the shear stress is smaller than the value required to promote slip. These variants have an invariant plane and lead to the B19' → B2 transformation along a fixed path. The existence of a transformation path with negligible plastic deformation makes the phenomenon reversible until dislocation slip occurs 2,3 .

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J. Braz. Soc. Mech. Sci. & Eng.  vol.31 número3

J. Braz. Soc. Mech. Sci. & Eng. vol.31 número3

Turbulent natural convection of air that happens into inner square cavity with localized heating from horizontal bottom surface has been numerically investigated. Localized heating is simulated by a centrally located heat source on the bottom wall, and two values of the dimensionless heat source length ∈ are considered in the present work. Solutions are obtained for several Rayleigh numbers with Prandtl number Pr = 0.70. The horizontal top surface is thermally insulated and the vertical surfaces are assumed to be the cold isothermal surfaces whereas the heat source on the bottom wall is isothermally heated. In this study, the Navier-Stokes equations are used considering a two-dimensional and turbulent flow in unsteady state. The Finite Element Method (FEM) with a Galerkin scheme is utilized for solving the conservation equations. The formulation of conservation equations is carried out for turbulent flow and the implementation of turbulent model is made by Large-Eddy Simulation (LES). The distributions of the stream function and of the temperature are determined as functions of thermal and geometrical parameters. The average Nusselt number Num is shown to increase with an increase in the Rayleigh number Ra as well as in the dimensionless heat source length ∈ . The results of this work can be applied to the design of electronic components.
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