Home-made Experimental Setup Research Articles

Effect of Repetitive High-Density Current Pulses on Plastic Deformation of Copper Wires under Stepwise Loading

High-density electric current pulses increase the plasticity and reduce the yield stress of metals with negligible heat generation. This effect has great potential for the development of energy-saving technologies for processing hard-to-deform metallic materials. Despite the long history of the study of electroplasticity, there is still no consensus on the physical nature of this effect. In this paper, the effect of repetitive pulses applied at the same or gradually increasing tensile stress on the plastic deformation of copper wire is investigated using a home-made experimental setup. The electroplasticity of the wire in the delivery state and after annealing is compared. It is shown that for a constant tensile stress, the incremental plastic deformation of the wire decreases with each successive pulse. This effect is stronger for annealed wires because they have a lower dislocation density and therefore a lower plasticity resource. The Joule heat release in the specimen and the heating due to plastic deformation are evaluated. The results obtained will be used to fit the parameters of the atomistic model being developed to describe the interaction of electron flow with dislocations.

Kissing the cheeks of Huygens

How well do the so-called cheeks of Huygens enforce a constant time of oscillation on a pendulum, independent of the amplitude of the pendulum swing? We use a video measurement tool to test it with a homemade experimental setup that can be fruitfully used in classroom and physics laboratory settings. Data fits reveal how well the setup confirms the usefulness of the cheeks of Huygens. Comparisons of computer model results with recorded data have been made for the same purpose. The equation of motion of a pendulum with a string of arbitrary length that winds along two surfaces of cycloidal cheeks is derived, too. Numerical solutions of this equation are used for the error analysis of measurements with the homemade setup.

High nitrogen and argon diffusion in cyclic olefin copolymer foil versus temperature

Measurements of nitrogen and argon diffusion coefficient in cyclic olefin copolymer (COC) have been performed at different temperatures ranging between 21 °C and 101 °C. Optical transparent COC foils have been prepared with 10 μm thickness and total surface of about 25 cm2. The foils have exhibited high purity in composition. The morphology of the COC surface has been investigated by Scanning Electron and Atomic Force Microscopies. The room temperature measured diffusion coefficients, of about 6.56 × 10−3 cm2/s and 6.30 × 10−3 cm2/s for N2 and Ar, respectively, have been obtained with a home-made experimental set-up by measuring the gas pressure gradient reduction applied to the two faces of COC thin foils versus the time. The foils show a significant increase of the N2 and Ar diffusion coefficients with the temperature. The native amorphous nature, the obtained nano-porous structure, the damage suffered by the thin foils of COC under high applied pressure are responsible of the evaluated high diffusion coefficients for nitrogen and argon gases. The experimental apparatus to measure the diffusion coefficients vs. temperature, the obtained results, the COC sheets microstructure, the measurements comparison with the literature data and possible COC applications in biomedicine are presented and discussed.

Numerical investigation of gas-solid heat transfer process and parameter optimization in shaft kiln for high-purity magnesia

As the core equipment for the production of high-purity magnesia, the determination of suitable structure and operating parameters has a significant impact on its efficient production. In present work, a three-dimensional numerical model of the high-purity magnesia shaft kiln is established to study the influence of different operating and structural parameters on outlet clinker temperature and outlet exhaust air temperature. The novelty is adding a convective term to the solid-phase equation of the energy model, as well as embedding the heat transfer coefficient and a modified Ergun’s correlation, obtained by a homemade experimental setup. Production data verify the accuracy and reliability of the model. The results indicate that with all other parameters being constant, the most significant impact on the outlet temperature of clinker and exhaust air is cooling air flow rate, followed by sintering gas flow rate, height below the burners and height above the burners. Finally, a combination of parameters for the 50,000 tons shaft kiln is obtained through orthogonal experiment and optimization, which is 2622 m3/h for sintering gas flow rate, 2422 m3/h for cooling air flow rate, 7.07 m for the height above the burners, and 12.14 m for the height below the burners.

A study of structural, morphological, optical and humidity sensing properties of CaCu3Ti4O12 powders synthesized by combustion method

Calcium Copper Titanate (CCTO) powder was synthesized via a low-cost facile combustion method at various calcination temperatures and times. The structural properties of the prepared CCTO powder were investigated from an X-ray diffraction (XRD) study, which confirmed the formation of the cubic phase with space group Im3. Further, Rietveld refinement of the XRD data was performed for the detailed structural analysis of the samples. The surface morphology of the CCTO powder was studied by Field Emission Scanning Electron Microscopy (FESEM), which showed an increase in particle size with an increase in the calcination temperature. The optical properties of the powders were examined by UV–vis Diffuse Reflectance Spectroscopy (DRS) and Photoluminescence Spectroscopy. The optical bandgap values, estimated from Tauc’s plot, increase with the increase in calcination temperature due to the elimination of structural defects or localized states inside the bandgap. The porous single-phase CCTO ceramic was subjected to a homemade experimental set-up combined with an LCR meter to investigate its room temperature humidity sensing characteristics in capacitive mode at various operating frequencies. At 100 Hz, the obtained humidity response curve for the CCTO-based sensor showed a 560 % increment in capacitance as the Relative Humidity (RH) changed from 40 % to 90 %.

Development of a home-made experimental set-up for in situ coupling under vacuum of conductivity measurements, x-ray absorption and Raman Spectroscopies on bundles of single-walled carbon nanotubes intercalated with alkali metals

Here, we report the development of a homemade experimental setup to perform under vacuum an in situ study of the physical properties of bundles of single-walled carbon nanotubes intercalated with rubidium ions using electrical conductivity, X-ray absorption and Raman measurements. This set-up was successfully used at the SAMBA beamline at the Soleil synchrotron. The electrical resistance displays an important drop with the stoichiometry (intercalation time). The Raman radial breathing modes and the G-band of the nanotubes clearly indicate an important electron transfer. The G-band behaviour features a transition from semiconducting to metallic nanotubes, confirmed by the electrical resistance measurements as a function of the temperature after rubidium intercalation. This set-up can be used for the study of any type of extremely air sensitive materials.

Breakthrough the communication bottleneck between sky and underwater

We report on an experimental demonstration of two-way communication between sky and underwater for the first time. Signal transmission from sky to underwater is realized by the thermoacoustic effect (TE), while from underwater to sky, this is based on the microwave vibration measurement (MVM). With a homemade experimental setup, the two-way transmission of “UESTC” is realized. This study suggests that TE combined with MVM has the potential to be used for two-way wireless communication between sky and underwater.

Thermal and Mechanical Analysis of Plywood Boards Thermally Enhanced with Phase Change Materials

Adding Phase Change Materials (PCM) in construction elements and materials increase their thermal mass, which may reduce temperature variation of indoor environment and improve thermal comfort of occupants. The present paper aims to study the thermal and mechanical impacts of embedding microencapsulated PCM in the adhesive of plywood boards. Mechanical properties of samples are measured using a standardized bending test; thermal mass is estimated with a homemade experimental setup based on a heated bed and two thermocouples. Tests were carried out on three different samples: a reference sample without PCM, a second sample with adhesive containing 25% of PCM, and a third sample with 30% of PCM. The most relevant results from the study showed that the mechanical properties of plywood boards were not significantly affected by the PCM, and the thermal mass was improved up to 19% on a variation of 30°C.

Fractional-Order Modeling and Identification for a Phantom EEG System

This paper is about dynamical modeling of an electroencephalographic (EEG) measurement chain. It is based on a home-made experimental setup consisting of an electrolytic medium, stimulated by external electrodes, the activity of which is measured at different points via other electrodes, connected to an EEG recording device. A novel noninteger-order model structure is then established with a so-called constant phase element, and a Nyquist-based graphical method is derived to identify the noninteger order. The study is completed with a recursive identification method for full parameter estimation in the model, and various applications on experimental data are presented, finally resulting in a fully identified noninteger order high-pass filter.

Tensile Piezoelectric Actuator: Fabrication, Characterization and Application

A multilayer piezoelectric actuator, with dimension of 10 mm×10 mm×60 mm, which can output a tensile displacement directly by exploring the d31 effect of piezoelectrics, was fabricated using soft Lead Zirconate Titanate (PZT) ceramics. The performance of the actuator was characterized by a special home-made experimental setup under electric fields varying from 200 to 1 000 V/mm with the preload varying from -150 to 100 N at room temperature. Results showed that it can output a maximum tensile displacement of 12 μm under unipolar electric field of 1 000 V/mm and preload was independent with generative displacement in the range of testing preload. Additionally, using the actuator, we built a micro loading apparatus, which can be used to test the fracture behavior of brittle materials.

Coupling Raman spectroscopy and drop tensiometry for in situ monitoring of radical polymerization in a single monomer droplet

Two complementary analytical techniques, Raman spectroscopy and drop tensiometry, were coupled in an original homemade experimental setup for in situ monitoring of radical polymerization in a single monomer droplet. Homopolymerizations of styrene and methyl methacrylate initiated by 2,2′-azobisisobutyronitrile in a single droplet surrounded by an aqueous medium containing sodium dodecylsulfate were investigated. Monomer conversion (from Raman spectroscopy) and interfacial properties (interfacial tension and dilational moduli, from drop tensiometry) were simultaneously acquired in situ.

Effect of the substrate temperature on the physical properties of sprayed-CdS films by using an automatized perfume atomizer

Cadmium sulfide (CdS) thin films were deposited onto glass substrates at different temperatures by the spray pyrolysis technique. A home-made experimental setup with an automatized perfume atomizer was implemented for the spray pyrolysis deposition. The temperature of the substrates was varied from 300 °C to 500 °C prior to the CdS deposition. The automatization and precise control of the spraying process produce CdS thin films with stable and controlled physical properties. The CdS stoichiometric ratio [S]/[Cd] and the bandgap energy were independent of the temperature of the substrate while the surface roughness decreased with increased temperature. The optical transmittance of the CdS films increased with increased substrate temperature, reaching values above 70% for wavelengths > 500 nm. A hexagonal crystalline structure was observed for the CdS films for all the substrate temperatures, however, the crystalline orientation of the CdS was dependent on the substrate temperature. Hall Effect measurements in Van der Pauw configuration confirmed low electrical resistivity values (~ 10−1 Ω-cm) and negative Hall coefficients (i.e. n-type) for the semiconducting CdS films. From the presented results, the samples deposited at 500 °C showed most adequate morphological, optical, electrical and structural conditions for potential implementation in photovoltaic applications. A good control and understanding of the physical properties of semiconducting thin films grown by low-cost and scalable techniques, such as the spray pyrolysis, represents an important step towards the development of nanostructures with high functionality.

Theoretical and experimental investigation on vertical tank technology for sinter waste heat recovery

In the present work, the gas flow pressure drop and gas–solid heat transfer characteristics in sinter bed layer of vertical tank were studied experimentally on the basis of the homemade experimental setup. The gas flow pressure drop through the sinter bed layer was measured with different gas velocity and particle diameters, as well as the sinter and air temperatures. The influences of gas superficial velocity and particle diameter on the gas flow pressure drop and gas solid heat transfer in sinter bed layer were analyzed in detail. The revised Ergun’s correlation and gas solid heat transfer correlation were obtained according to the regression analysis of experimental data. It is found that, the pressure drop of unit bed layer height gradually increases as a quadratic relationship with increasing the gas superficial velocity, and decreases as an exponential relationship with the increase of sinter particle diameter. For a given sinter temperature, the heat transfer coefficient in sinter bed layer increases with increasing the gas superficial velocity, and increases with decreasing the sinter particle diameter. In addition, the heat transfer coefficient also gradually increases with increasing the sinter temperature at the same gas superficial velocity and sinter particle diameter. The mean deviations between the experimental data obtained from this work and the values calculated by the revised Ergun’s correlation and the experimental heat transfer correlation are 7.22% and 4.22% respectively, showing good prediction.

Numerical investigation of gas-solid heat transfer process in vertical tank for sinter waste heat recovery

In the present paper, a three-dimensional mathematical model is established on the basis of the porous media theory and the local thermal non-equilibrium model, to investigate the gas solid heat transfer in sinter bed layer of vertical tank. The reliability of mathematical model is verified through the comparison of calculated results with the experimental results according to the homemade experimental setup. Numerical simulations are conducted to examine the influences of different structural and operating parameters on the air and sinter temperatures in sinter bed layer. Furthermore, an optimal combination of each parameter is determined through the orthogonal experiment for improving the outlet exergy of cooling air. The results show that the outlet air and sinter temperatures decrease with the air flow rate increasing. Decreasing the inner diameter and height of cooling section, or increasing the particle diameter, the outlet air temperature decreases and the outlet sinter temperature increases. Based on the sinter annual output of 3,900,000tons for 360m2 sintering machine, the suitable structural and operating parameters of vertical tank are 150kg/s for the air flow rate, 0.015m for the sinter particle diameter, 10m for the inner diameter of cooling section and 8m for the height of cooling section.

The oxidation behavior of A3-3 matrix graphite

The effects of temperature on the oxidation behavior of the A3-3 matrix graphite (MG) in the temperature range 798-973 K in air with a flow rate of 100 ml/min to burn-offs of 10-15 wt%, were investigated by a home-made thermo-gravimetric experimental setup. The oxidation rate (OR) increases significantly with the temperature. The OR at 973 K is over 70 times faster than at 798 K. The oxidation kinetics of A3-3 MG in air at temperatures up to 973 K is in the reaction control regime, where the activation energy is 176 kJ/mol and the Arrhenius equation could be described as: OR=2.9673×108·exp(-21124.8/T) wt%/min. The relatively lower activation energy of MG than that of structural nuclear graphite indicates that MG is more easily oxidized.

Electrothermal explosion under pressure: Ti–C blends in porous electroconducting envelope

Influence of applied pressure P and intensity of Joule heating on electrothermal explosion (ETE) in Ti–C blends placed in a porous electroconducting envelope was studied by using a home-made experimental setup. A distinctive feature of this system is non-linear warm-up prior to initiation of ETE. A non-linear temperature growth during pre-explosion warm-up was associated with gradual decrease in the electrical resistance of the sample caused by intensification of mass transfer processes leading to an increase in current density and hence in heating rate. During the warm-up period, the extent of conversion was found to attain a value of about 15%. In classical theory of gasless combustion, chemical reaction within the warm-up zone is neglected and it is postulated that combustion reaction gets started at temperatures close to the melting point of a low-melting reagent. Our results cast some doubt on the validity of the above adoptions and thus shed new light on the mechanism of SHS reactions in heterogeneous systems.

Experimental study of gas–solid overall heat transfer coefficient in vertical tank for sinter waste heat recovery

This work experimentally investigates the gas–solid heat transfer behavior in vertical tank for sinter waste heat recovery. With the purpose of predicting the heat transfer Nusselt number, a homemade experimental setup is built to obtain the temperatures of cooling air and sinter particles over time. Sinter particles of average diameter d = 18, 27 and 36 mm with a range of sphericity of 0.68 ≤ Φ ≤ 0.89 are used in the experiments. The experiments are performed in the range of gas superficial velocity of 1.04~1.75 m/s and the sinter temperature in bed layer from 100 to 750 °C. The influences of gas superficial velocity and sinter particle diameter on the gas–solid overall heat transfer coefficient are analyzed in detail for the covered test cases. The heat transfer Nusselt number is obtained according to the regression analysis of experimental data, and the reliability of the heat transfer Nusselt number is also verified. It is found that the gas–solid overall heat transfer coefficient increases with the increase of gas superficial velocity, and decreases with increasing sinter particle diameter. A small increase in gas–solid overall heat transfer coefficient with the temperature of sinter particles is also observed in the experiments. Compared with the previous literature correlations, the experimental correlation for gas–solid heat transfer in the form of Nusselt number best fits the experimental data. The mean deviation between the experimental data of Nusselt number obtained from this work and the values calculated by the experimental heat transfer correlation is 4.37%, showing good prediction.

The Study of the Delay Kerr Loops Induced by Femtosecond Laser Pulses in GdFeCo Film

To study the evolution of the coercivity and magnetization induced by femtosecond laser pulses in GdFeCo film at distinct pump–probe delays and reveal the laser-induced magnetization reversal process, the static delay Kerr loops were measured by the traditional time-resolved magneto-optical Kerr effect technique. The results showed that the loops contained memory effect from external field history and could not reflect the real change of coercivity and magnetization after laser pump. To eliminate the memory effect, a home-made experimental setup of photomagnetic synchronized time-resolved magneto-optical Kerr effect technology was used to measure the dynamic delay Kerr loops and reveal the real evolution of the coercivity and magnetization after laser pump, whose results are of great importance in real magneto-optical recording application.

Phase transitions of bulk and nanocrystalline La1−xSrxMnO3 (x = 0.35 and 0.37) perovskite manganite materials using in situ ultrasonic studies

La1−xSrxMnO3 perovskite manganite materials with two compositions, namely x=0.35 and 0.37, both at bulk and nanoscale, were prepared by solid-state reaction and sonochemical reactor methods, respectively. The magnetic phase transition temperature of the prepared bulk and nanosamples was evaluated by in situ ultrasonic velocity and attenuation measurements. A home-made experimental setup was used for in situ measurement of ultrasonic velocities and attenuation over a wide range of temperatures (from 300 to 400K). The observed anomalous lattice-softening behavior in the ultrasonic parameters was used to study the phase transition temperature (Curie temperature, TC), i.e., from paramagnetic to ferromagnetic phase, both in bulk and nanostructured perovskite samples. Further, the ultrasonic measurements confirmed that sharp and broad transitions occur in bulk and nanostructured perovskite manganite materials, respectively. The Curie temperature for nanostructured perovskite samples was lower than that for the corresponding bulk perovskite sample, which was clearly identified by ultrasonic measurements.

Design of Labview Based Equipment for Measuring Thermally Stimulated Current

In this paper, we improved the home-made EL experimental set-up, have increased the function of TSC, enable the joint measurement of EL and TSC to measure the trap of shallow and deep. It is significant to study material properties. through the Labview8.6 software programming, the data of temperature and current could be collected, then we can get the curve that the current changes with temperature, it is the TSC curve. Experiment result proved the reliability of laboratory equipment.