Search results for: optical strain measurement

Authors: Bouwer Kleynhans

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The built environment is responsible for about 40% of the world’s energy consumption and generates one third of global carbon dioxide emissions. The Green Building Council of South Africa’s (GBCSA) current rating tools are all for new buildings. By far the largest portion of buildings exist stock and therefore the need to develop a certification tool for existing buildings. Direct energy measurement comprises 27% of the total available points in this tool. The aim of this paper is to describe the development process of a green star certification tool for existing buildings in South Africa with specific emphasis on the energy measurement criteria. Successful implementation of this tool within the property market will ensure a reduced carbon footprint of buildings.

Keywords: certification tool, development process, energy consumption, green buildings

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Authors: Jen-Yuan Wang, Min-Chuan Wang, Der-Jun Jan

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Polymer electrolytes can be classified into four major categories, solid polymer electrolytes (SPEs), gel polymer electrolytes (GPEs), polyelectrolytes and composite polymer electrolytes. SPEs suffer from low ionic conductivity at room temperature. The main problems for GPEs are the poor thermal stability and mechanical properties. In this study, a GPE containing PMMA and succinonitrile is prepared to solve the problems mentioned above, and applied to the assembly of a quasi-solid-state electrochromic device (ECD). In the polymer electrolyte, poly(methyl methacrylate) (PMMA) is the polymer matrix and propylene carbonate (PC) is used as the plasticizer. To enhance the mechanical properties of this GPE, succinonitrile (SN) is introduced as the additive. For the electrochromic materials, tungsten oxide (WO3) is used as the cathodic coloring film, which is fabricated by pulsed dc magnetron reactive sputtering. For the anodic coloring material, Prussian blue nanoparticles (PBNPs) are synthesized and coated on the transparent Sn-doped indium oxide (ITO) glass. The thickness of ITO, WO3 and PB film is 110, 170 and 200 nm, respectively. The size of the ECD is 5×5 cm2. The effect of the introduction of SN into the GPEs is discussed by observing the electrochromic behaviors of the WO3-PB ECD. Besides, the composition ratio of PC to SN is also investigated by measuring the ionic conductivity. The optimized ratio of PC to SN is 4:1, and the ionic conductivity under this condition is 6.34x10-5 S∙cm-1, which is higher than that of PMMA/PC (1.35x10-6 S∙cm-1) and PMMA/EC/PC (4.52x10-6 S∙cm-1). This quasi-solid-state ECD fabricated with the PMMA/SN based GPE shows an optical contrast of ca. 53% at 690 nm. The optical transmittance of the ECD can be reversibly modulated from 72% (bleached) to 19% (darkened), by applying potentials of 1.5 and -2.2 V, respectively. During the durability test, the optical contrast of this ECD remains 44.5% after 2400 cycles, which is 83% of the original one.

Keywords: electrochromism, tungsten oxide, prussian blue, poly(methyl methacrylate), succinonitrile

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Authors: Delele Worku Ayele, Bing-Joe Hwang

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A method that does not employ hot injection techniques has been developed for the size-tunable synthesis of high-quality CdSe quantum dots (QDs) with a zinc blende structure. In this environmentally benign synthetic route, which uses relatively less toxic precursors, solvents, and capping ligands, CdSe QDs that absorb visible light are obtained. The size of the as-prepared CdSe QDs and, thus, their optical properties can be manipulated by changing the microwave reaction conditions. The QDs are characterized by XRD, TEM, UV-vis, FTIR, time-resolved fluorescence spectroscopy, and fluorescence spectrophotometry. In this approach, the reaction is conducted in open air and at a much lower temperature than in hot injection techniques. The use of microwaves in this process allows for a highly reproducible and effective synthesis protocol that is fully adaptable for mass production and can be easily employed to synthesize a variety of semiconductor QDs with the desired properties. The possible application of the as-prepared CdSe QDs has been also assessed using deposition on TiO2 films.

Keywords: CdSe QDs, Na2SeSO3, microwave (MW), oleic acid, mass production, average life time

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Authors: Farzana Majid, Mahwish Bashir, Ammara, Attia Falak

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Zirconia nanoparticles have gained significant attention due to their excellent mechanical strength, thermal properties, biocompatibility, and catalytic activity. Tetragonal zirconia holds the greatest efficacy for surgical implants and coatings when it comes to the three zirconia phases (monoclinic, tetragonal, and cubic). However, its stability at higher temperatures and transformation to the monoclinic phase upon cooling are challenging. In this research, zirconia nanoparticles were prepared using microwave-assisted sol-gel method with varying microwave powers (100 W, 300 W, 500 W, 700 W, & 900 W). Organic stabilizing agent, i.e., eggshell powder, was used to stabilize the tetragonal phase. Fourier transform infrared spectroscopy (FTIR) confirmed the phase-pure tetragonal zirconia, corroborating the XRD data. Optical properties, including the optical bandgap, were studied using UV/Visible and PL spectroscopies. The synthesized ZrO2 nanoparticles exhibited excellent photocatalytic degradation efficiency in the degradation of methylene blue (MB) dye under UV irradiation. The findings demonstrate the potential of these ZrO2 nanoparticles as a viable alternative photocatalyst for the efficient degradation of various dyes in contaminated water.

Keywords: zirconia nanoparticles, sol-gel, photocataylsis, wter purification

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Authors: T. M. Aminu, A. Salisu, B. Abdu, H. U. Alhassan, T. H. Dharma

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Thin films of CuAlO2 were deposited on clean glass substrate using the chemical solution deposition (sol-gel) method of deposition with CuCl and AlCl3 taken as the starting materials. CuCl was dissolved in HCl while AlCl₃ in distilled water, pH value of the mixture was controlled by addition of NaOH. The samples were annealed at different temperatures in order to determine the effect of annealing temperatures on the morphological and optical properties of the deposited CuAlO₂ thin film. The surface morphology reveals an improved crystalline as annealing temperature increases. The results of the UV-vis and FT-IR spectrophotometry indicate that the absorbance for all the samples decreases sharply from a common value of about 89% at about 329 nm to a range of values of 56.2%-35.2% and the absorption / extinction coefficients of the films decrease with increase in annealing temperature from 1.58 x 10⁻⁶ to1.08 x 10⁻⁶ at about 1.14eV in the infrared region to about 1.93 x 10⁻⁶ to 1.29 x 10⁻⁶ at about 3.62eV in the visible region, the transmittance, reflectance and band gaps vary directly with annealing temperature, the deposited films were found to be suitable in optoelectronic applications.

Keywords: copper aluminium-oxide (CuAlO2), absorbance, transmittance, reflectance, band gaps

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Authors: M. Miriam Hernández-Arroyo, Ivonne Caro-Gonzales, Miguel Ángel Plascencia-Espinosa, Sergio R. Trejo-Estrada

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A large biodiversity of Lactobacillus strains has been detected in traditional foods and beverages from Mexico. A selected strain of Lactobacillus sp - PODI-20, used for the obtained from an artisanal fermented beverage was cultivated in different carbon sources in a complex medium, in order to define which carbon sourced induced more effectively the isomerization of arabinose by cell fractions obtained by fermentation. Four different carbon sources were tested in a medium containing peptone and yeast extract and mineral salts. Glucose, galactose, arabinose, and lactose were tested individually at three different concentrations: 3.5, 6, and 10% w/v. The biomass yield ranged from 1.72 to 17.6 g/L. The cell pellet was processed by mechanical homogenization. Both fractions, the cellular debris, and the lysis supernatant were tested for their ability to isomerize arabinose into ribulose. The highest yield of isomer was 12 % of isomerization in the supernatant fractions; whereas up to 9.3% was obtained by the use of cell debris. The isomerization of arabinose has great significance in the production of lactic acid by fermentation of complex carbohydrate hydrolysates.

Keywords: isomerase, tagatose, aguamiel, isomerization

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Authors: Touka Nassim, Tabli Dalila

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In this study, CuO thin films synthesized via simple sol-gel method, have been deposited on glass substrates by the spin coating technique and annealed at various temperatures. Samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier-transform infrared (FT-IR) and Raman spectroscopy, and UV-visible spectroscopy. The structural characterization by XRD reveals that the as prepared films were tenorite phase and have a high level of purity and crystallinity. The crystallite size of the CuO films was affected by the annealing temperature and was estimated in the range 20-31.5 nm. SEM images show a homogeneous distribution of spherical nanoparticles over the surface of the annealed films at 350 and 450 °C. Vibrational Spectroscopy revealed vibration modes specific to CuO with monolithic structure on the Raman spectra at 289 cm−1 and on FT-IR spectra around 430-580 cm−1. Electronic investigation performed by UV–Visible spectroscopy showed that the films have high absorbance in the visible region and their optical band gap increases from 2.40 to 2.66 eV (blue shift) with increasing annealing temperature from 350 to 550 °C.

Keywords: Sol-gel, Spin coating method, Copper oxide, Thin films

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Authors: Tejeet Singh, Ishavneet Singh

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The present study focused on carrying out the creep analysis in an isotropic thick-walled composite cylindrical pressure vessel composed of aluminum matrix reinforced with silicon-carbide in particulate form. The creep behavior of the composite material has been described by the threshold stress based creep law. The values of stress exponent appearing in the creep law were selected as 3, 5 and 8. The constitutive equations were developed using well known von-Mises yield criteria. Models were developed to find out the distributions of creep stress and strain rate in thick-walled composite cylindrical pressure vessels under internal pressure. In order to obtain the stress distributions in the cylinder, the equilibrium equation of the continuum mechanics and the constitutive equations are solved together. It was observed that the radial stress, tangential stress and axial stress increases along with the radial distance. The cross-over was also obtained almost at the middle region of cylindrical vessel for tangential and axial stress for different values of stress exponent. The strain rates were also decreasing in nature along the entire radius.

Keywords: steady state creep, composite, cylinder, pressure

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Authors: Edvard Kokanyan, Narine Babajanyan, Ninel Kokanyan, Marco Bazzan

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Lithium niobate (LN) crystals, renowned for their exceptional nonlinear optical, electro-optical, piezoelectric, and photorefractive properties, stand as foundational materials in diverse fields of study and application. While they have long been utilized in frequency converters of laser radiation, electro-optical modulators, and holographic information recording media, LN crystals doped with rare earth ions represent a compelling frontier for modern compact devices. These materials exhibit immense potential as key components in infrared lasers, optical sensors, self-cooling systems, and radiation balanced laser setups. In this study, we present the successful synthesis of Ho-doped lithium niobate (LN:Ho) thin films on sapphire substrates employing the Sol-Gel technique. The films exhibit a strong crystallographic orientation along the perpendicular direction to the substrate surface, with X-ray diffraction analysis confirming the predominant alignment of the film's "c" axis, notably evidenced by the intense (006) reflection peak. Further characterization through Raman spectroscopy, employing a confocal Raman microscope (LabRAM HR Evolution) with exciting wavelengths of 532 nm and 785 nm, unraveled intriguing insights. Under excitation with a 785 nm laser, Raman scattering obeyed selection rules, while employing a 532 nm laser unveiled additional forbidden lines reminiscent of behaviors observed in bulk LN:Ho crystals. These supplementary lines were attributed to luminescence induced by excitation at 532 nm. Leveraging data from anti-Stokes Raman lines facilitated the disentanglement of luminescence spectra from the investigated samples. Surface scanning affirmed the uniformity of both structure and luminescence across the thin films. Notably, despite the robust orientation of the "c" axis perpendicular to the substrate surface, Raman signals indicated a stochastic distribution of "a" and "b" axes, validating the mosaic structure of the films along the mentioned axis. This study offers valuable insights into the structural properties of Ho-doped lithium niobate thin films, with the observed luminescence behavior holding significant promise for potential applications in optoelectronic devices.

Keywords: lithium niobate, Sol-Gel, luminescence, Raman spectroscopy

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Authors: Javad Sadoghi Yazdi, Robb Eric S. Moss

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This paper utilizes a probabilistic liquefaction triggering method for modeling post-liquefaction ground deformation. This cone penetration test CPT-based liquefaction triggering is employed to estimate the factor of safety against liquefaction (FSL) and compute the maximum cyclic shear strain (γmax). The study identifies a maximum PL value of 90% across various relative densities, which challenges the decrease from 90% to 70% as relative density decreases. It reveals that PL ranges from 5% to 50% for volumetric strain (εvol) less than 1%, while for εvol values between 1% and 3.2%, PL spans from 50% to 90%. The application of the CPT-based simplified liquefaction triggering procedures has been employed in previous researches to estimate liquefaction ground-failure indices, such as the Liquefaction Potential Index (LPI) and Liquefaction Severity Number (LSN). However, several studies have been conducted to highlight the variability in liquefaction probability calculations, suggesting a more accurate depiction of liquefaction likelihood. Consequently, the utilization of these simplified methods may not offer practical efficiency. This paper further investigates the efficacy of various established liquefaction vulnerability parameters, including LPI and LSN, in explaining the observed liquefaction-induced damage within residential zones of Christchurch, New Zealand using results from CPT database.

Keywords: cone penetration test (CPT), liquefaction, postliquefaction, ground failure

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Authors: Bo Liu, Qingshan Kong, Weiqing Huang

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With the rapid development of modern communication, diagnosing the fiber-optic quality and faults in real-time is widely focused. In this paper, a Labview-based system is proposed for fiber-optic faults detection. The wavelet threshold denoising method combined with Empirical Mode Decomposition (EMD) is applied to denoise the optical time domain reflectometer (OTDR) signal. Then the method based on Gabor representation is used to detect events. Experimental measurements show that signal to noise ratio (SNR) of the OTDR signal is improved by 1.34dB on average, compared with using the wavelet threshold denosing method. The proposed system has a high score in event detection capability and accuracy. The maximum detectable fiber length of the proposed Labview-based system can be 65km.

Keywords: empirical mode decomposition, events detection, Gabor transform, optical time domain reflectometer, wavelet threshold denoising

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Authors: Maria Do Carmo Baracho De Alencar, Marciene Campos Fialho, Maria Do Carmo Vitório Ramos

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The subjects affected by Repetitive Strain Injury/Work Related Musculoskeletal Disorder (RSI/WRMSD) face an everyday life marked by pain, feelings of worthlessness and incapacity caused by the disease, and aggravated often because of discrimination society. Aim: To investigate the experiences and feelings of workers affected by RSI/WRMSD in removal from work situations and to understand the repercussions on mental health. Methods: Clinical records of workers were consulted, opened from July 1, 2014, to July 1, 2015, at the Reference Center for Worker's Health, in Santos city-SP. Selection of workers affected by RSI /WRMSD and who had experienced the removal from work situation due to the disease, and invitation to participate in the study. Semi-structured and individual interviews were carried out based on a pre-elaborated script, and for thematic content analysis. Results: Of a total of 502 medical records, 157 were selected, and of these, 18 workers participated in the interviews, both gender, most of them with low education level, aged between 35 and 56 years, and from different professions. Diseases affected several physical body regions and some workers had more than one body region affected by chronic pain. In the testimonies emerged the psychic suffering by the process of illness at work, fear of dismissal, invisibility of pain, in medical expertise attendance, by the incapacity to perform tasks that were easily achievable, with feelings of uselessness, revolt, and injustice, among others. Conclusion: The workers need to be readapted to new life situations, and the study promotes reflections on the need for more interdisciplinary actions and of the Psychology to the workers affected by RSI/ WRMSD.

Keywords: repetitive strain injury, cumulative trauma disorder, absence from work, mental health, occupational health

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Authors: Shimayali Kaushal, Nitesh Priyadarshi, Nitin Kumar Singhal

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Food borne bacterial species have been identified as major pathogens in most of the severe pathogen-related diseases among humans which result in great loss to human health and food industry. Conventional methods like plating and enzyme-linked immune sorbent assay (ELISA) are time-consuming, laborious and require specialized instruments. Nanotechnology has emerged as a great field in case of rapid detection of pathogens in recent years. The AuNRs material has good electro-optical properties due to its larger light absorption band and scattering in surface plasmon resonance wavelength regions. By exploiting the sugar-based adhesion properties of microorganism, we can use the glycoconjugates capped gold nanorods as a potential nanobiosensor to detect the foodborne pathogen. In the present study, polyethylene glycol (PEG) coated gold nanorods (AuNRs) were prepared and functionalized with different types of carbohydrates and further characterized by UV-Visible spectrophotometry, dynamic light scattering (DLS), transmission electron microscopy (TEM). The reactivity of above said nano-biosensor was probed by lectin binding assay and also by different strains of foodborne bacteria by using spectrophotometric and microscopic techniques. Due to the specific interaction of probe with foodborne bacteria (Escherichia coli, Pseudomonas aeruginosa), our nanoprobe has shown significant and selective ablation of targeted bacteria. Our findings suggest that our nanoprobe can be an ideal candidate for selective optical detection of food pathogens and can reduce loss to the food industry.

Keywords: glyco-conjugates, gold nanorods, nanobiosensor, nanoprobe

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Authors: L. Chetibi, D. Hamana, T. O. Busko, M. P. Kulish, S. Achour

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TiO2 nanostructures have attracted much attention due to their optical, dielectric and photocatalytic properties as well as applications including optical coating, photocatalysis and photoelectrochemical solar cells. This work aims to prepare TiO2 nanofibers (NFs) on titanium substrate (Ti) by in situ oxidation of Ti foils in a mixture solution of concentrated H2O2 and NaOH followed by proton exchange and calcinations. Scanning Electron microscopy (SEM) revealed an obvious network of TiO2 nanofibers. The photoluminescence (PL) spectra of these nanostructures revealed a broad intense band in the visible light range with a reduced near edge band emission. The PL bands in the visible region, mainly, results from surface oxygen vacancies and others defects. After irradiation with Ti+ ions (the irradiation energy was E = 140 keV with doses of 1013 ions/cm2), the intensity of the PL spectrum decreased as a consequence of the radiation treatment. The irradiation with Ti+ leads to a reduction of defects and generation of non irradiative defects near to the level of the conduction band as evidenced by the PL results. On the other hand, reducing the surface defects on TiO2 nanostructures may improve photocatalytic and optoelectronic properties of this nanostructure.

Keywords: TiO2, nanofibers, photoluminescence, irradiation

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Authors: Tae An Kim, Hyo Lim Kang, Hye Won Han, Seung Ho Han

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The drive shaft of passenger vehicle has its own function such as transmitting the engine torque from the gearbox and differential gears to the wheels. It must also compensate for all variations in angle or length resulting from manoeuvring and deflection for perfect synchronization between joints. Torsional fatigue failures occur frequently at the connection parts of the spline joints in the end of the drive shaft. In this study, the fatigue life of a drive shaft of passenger vehicle was estimated by using the finite element analysis. A commercial software of n-Code was applied under twisting load conditions, i.e. 0~134kgf•m and 0~188kgf•m, in which the shear strain range-fatigue life relationship considering Signed Shear method, Smith-Watson-Topper equation, Neuber-Hoffman Seeger method, size sensitivity factor and surface roughness effect was taken into account. The estimated fatigue life was verified by a twisting load test of the real drive shaft in a test rig. (Human Resource Training Project for Industry Matched R & D, KIAT, N036200004).

Keywords: drive shaft, fatigue life estimation, passenger vehicle, shear strain range-fatigue life relationship, torsional fatigue failure

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Authors: Amit Kumar, Himanshu Singal, Arnav Bhavsar

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In this modern era of automation, most of the academic exams and competitive exams are Multiple Choice Questions (MCQ). The responses of these MCQ based exams are recorded in the Optical Mark Reader (OMR) sheet. Evaluation of the OMR sheet requires separate specialized machines for scanning and marking. The sheets used by these machines are special and costs more than a normal sheet. Available process is non-economical and dependent on paper thickness, scanning quality, paper orientation, special hardware and customized software. This study tries to tackle the problem of evaluating the OMR sheet without any special hardware and making the whole process economical. We propose an image processing based algorithm which can be used to read and evaluate the scanned OMR sheets with no special hardware required. It will eliminate the use of special OMR sheet. Responses recorded in normal sheet is enough for evaluation. The proposed system takes care of color, brightness, rotation, little imperfections in the OMR sheet images.

Keywords: OMR, image processing, hough circle trans-form, interpolation, detection, binary thresholding

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Authors: Hongda Guo, Wenxia Sima

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Transformer oil is widely used in power systems because of its excellent insulation properties. The accurate measurement of electric field and space charge distribution in transformer oil under high voltage impulse has important theoretical and practical significance, but still remains challenging to date because of its low Kerr constant. In this study, the continuous electric field and space charge distribution over time between parallel-plate electrodes in high-voltage pulsed transformer oil based on the Kerr effect is directly measured using a linear array photoelectrical detector. Experimental results demonstrate the applicability and reliability of this method. This study provides a feasible approach to further study the space charge effects and breakdown mechanisms in transformer oil.

Keywords: electric field, Kerr, space charge, transformer oil

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Authors: Esteban Morales Murillo, Ephraim Mokgothu

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This paper presents the findings of a study conducted to investigate the wall thinning in a piping system carrying a mix of hydrocarbons in a petrochemical plant. A detailed investigation including optical inspection and several characterisation techniques such as optical microscopy, SEM/EDX, and XRF/C-S analyses was conducted. The examinations revealed that the wall thinning in the piping system was a result of high-temperature H2/H2S corrosion caused by a susceptible material for this mechanism and operating parameters and effluent concentrations beyond the prescribed limits. The sulfide layers found to testify to the large amounts of H2S that led to material degradation. Deposit analysis revealed that it consisted primarily of carbon, oxygen, iron, chromium and sulfur. Metallographic examinations revealed that the attack initiated from the internal surface and that spheroidization of carbides did occur. The article discusses in detail the contribution failure factors on the Couper-Gorman H2/H2S curves to draw conclusions. Recommendations based on the above findings are also discussed.

Keywords: corrosion, Couper-Gorman, high-temperature corrosion, sulfidation, wall thinning, piping system

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Authors: Wilaiwan Sornpoon, Sébastien Bonnet, Savitri Garivait

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Continuous measurements of greenhouse gases (GHGs) emitted from soils are required to understand diurnal and seasonal variations in soil emissions and related mechanism. This understanding plays an important role in appropriate quantification and assessment of the overall change in soil carbon flow and budget. This study proposes to monitor GHGs emissions from soil under sugarcane cultivation in Thailand. The measurements were conducted over 379 days. The results showed that the total net amount of GHGs emitted from sugarcane plantation soil amounts to 36 Mg CO2eq ha-1. Carbon dioxide (CO2) and nitrous oxide (N2O) were found to be the main contributors to the emissions. For methane (CH4), the net emission was found to be almost zero. The measurement results also confirmed that soil moisture content and GHGs emissions are positively correlated.

Keywords: soil, GHG emission, sugarcane, agriculture, Thailand

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Authors: Hamdy M. Youssef

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In this work, the usual Euler–Bernoulli nanobeam has been modeled in the context of Lord-Shulman thermoelastic theorem, which contains non-Fourier heat conduction law. The nanobeam has been subjected to a constant magnetic field and ramp-type thermal loading. The Laplace transform definition has been applied to the governing equations, and the solutions have been obtained by using a direct approach. The inversions of the Laplace transform have been calculated numerically by using Tzou approximation method. The solutions have been applied to a nanobeam made of silicon nitride. The distributions of the temperature increment, lateral deflection, strain, stress, and strain-energy density have been represented in figures with different values of the magnetic field intensity and ramp-time heat parameter. The value of the magnetic field intensity and ramp-time heat parameter have significant effects on all the studied functions, and they could be used as tuners to control the energy which has been generated through the nanobeam.

Keywords: nanobeam, vibration, constant magnetic field, ramp-type thermal loading, non-Fourier heat conduction law

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Authors: Vikas Kumar, V. H. Saran, Arpit Mathur, Avik Kathuria

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The evaluation of biodynamic responses of the human body to whole body vibration exposure is necessary to quantify the exposure effects. A force plate model has been designed with the help of CAD software, which was investigated by performing the modal, stress and strain analysis using finite element approach in the software. The results of the modal, stress and strain analysis were under the limits for measurements of biodynamic responses to whole body vibration. The physical model of the force plate was manufactured and fixed to the vibration simulator and further used in the experimentation for the evaluation of apparent mass responses of the ten recruited subjects standing in an erect posture exposed to vertical whole body vibration. The platform was excited with sinusoidal vibration at vibration magnitude: 1.0 and 1.5 m/s2 rms at different frequency of 2, 3, 4, 5, 6, 8, 10, 12.5, 16 and 20 Hz. The results of magnitude of normalised apparent mass have shown the trend observed in the many past studies. The peak in the normalised apparent mass has been observed at 4 & 5 Hz frequency of vertical whole body vibration. The nonlinearity with respect to vibration magnitude has been also observed in the normalised apparent mass responses.

Keywords: whole body vibration, apparent mass, modeling, force plate

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Authors: Swapnil Kumar Singh

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Gamma-ray bursts (GRB's), short and intense pulses of low-energy γ rays, have fascinated astronomers and astrophysicists since their unexpected discovery in the late sixties. GRB'sare accompanied by long-lasting afterglows, and they are associated with core-collapse supernovae. The detection of delayed emission in X-ray, optical, and radio wavelength, or "afterglow," following a γ-ray burst can be described as the emission of a relativistic shell decelerating upon collision with the interstellar medium. While it is fair to say that there is strong diversity amongst the afterglow population, probably reflecting diversity in the energy, luminosity, shock efficiency, baryon loading, progenitor properties, circumstellar medium, and more, the afterglows of GRBs do appear more similar than the bursts themselves, and it is possible to identify common features within afterglows that lead to some canonical expectations. After an initial flash of gamma rays, a longer-lived "afterglow" is usually emitted at longer wavelengths (X-ray, ultraviolet, optical, infrared, microwave, and radio). It is a slowly fading emission at longer wavelengths created by collisions between the burst ejecta and interstellar gas. In X-ray wavelengths, the GRB afterglow fades quickly at first, then transitions to a less-steep drop-off (it does other stuff after that, but we'll ignore that for now). During these early phases, the X-ray afterglow has a spectrum that looks like a power law: flux F∝ E^β, where E is energy and beta is some number called the spectral index. This kind of spectrum is characteristic of synchrotron emission, which is produced when charged particles spiral around magnetic field lines at close to the speed of light. In addition to the outgoing forward shock that ploughs into the interstellar medium, there is also a so-called reverse shock, which propagates backward through the ejecta. In many ways," reverse" shock can be misleading; this shock is still moving outward from the restframe of the star at relativistic velocity but is ploughing backward through the ejecta in their frame and is slowing the expansion. This reverse shock can be dynamically important, as it can carry comparable energy to the forward shock. The early phases of the GRB afterglow still provide a good description even if the GRB is highly collimated since the individual emitting regions of the outflow are not in causal contact at large angles and so behave as though they are expanding isotropically. The majority of afterglows, at times typically observed, fall in the slow cooling regime, and the cooling break lies between the optical and the X-ray. Numerous observations support this broad picture for afterglows in the spectral energy distribution of the afterglow of the very bright GRB. The bluer light (optical and X-ray) appears to follow a typical synchrotron forward shock expectation (note that the apparent features in the X-ray and optical spectrum are due to the presence of dust within the host galaxy). We need more research in GRB and Particle Physics in order to unfold the mysteries of afterglow.

Keywords: GRB, synchrotron, X-ray, isotropic energy

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Authors: Mayandi Ramanathan

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Gas turbine blades see the most aggressive thermal stress conditions within the engine, due to high Turbine Entry Temperatures in the range of 1500 to 1600°C. The blades rotate at very high rotation rates and remove a significant amount of thermal power from the gas stream. At high temperatures, the major component failure mechanism is a creep. During its service over time under high thermal loads, the blade will deform, lengthen and rupture. High strength and stiffness in the longitudinal direction up to elevated service temperatures are certainly the most needed properties of turbine blades and gas turbine components. The proposed advanced Ti alloy material needs a process that provides a strategic orientation of metallic ordering, uniformity in composition and high metallic strength. The chemical composition of the proposed Ti alloy material (25% Ta/(Al+Ta) ratio), unlike Ti-47Al-2Cr-2Nb, has less excess Al that could limit the service life of turbine blades. Properties and performance of Ti-47Al-2Cr-2Nb and Ti-6Al-4V materials will be compared with that of the proposed Ti alloy material to generalize the performance metrics of various gas turbine components. This paper will involve the summary of the effects of additive manufacturing and heat treatment process conditions on the changes in the phase composition, grain structure, lattice structure of the material, tensile strength, creep strain rate, thermal expansion coefficient and fracture toughness at different temperatures. Based on these results, additive manufacturing and heat treatment process conditions will be optimized to fabricate turbine blade with Ti-43Al matrix alloyed with an optimized amount of refractory Ta metal. Improvement in service temperature of the turbine blades and corrosion resistance dependence on the coercivity of the alloy material will be reported. A correlation of phase composition and creep strain rate will also be discussed.

Keywords: high temperature materials, aerospace, specific strength, creep strain, phase composition

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Authors: Hao Wang, Shengchun Wang, Weidong Wang

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On the influence of train vibration and environmental noise on the measurement of track wear, we proposed a method for automatic extraction of circular arc on the inner or outer side of the rail waist and achieved the high-precision registration of rail profile. Firstly, a polynomial fitting method based on truncated residual histogram was proposed to find the optimal fitting curve of the profile and reduce the influence of noise on profile curve fitting. Then, based on the curvature distribution characteristics of the fitting curve, the interval search algorithm based on dynamic window’s maximum curvature entropy was proposed to realize the automatic segmentation of small circular arc. At last, we fit two circle centers as matching reference points based on small circular arcs on both sides and realized the alignment from the measured profile to the standard designed profile. The static experimental results show that the mean and standard deviation of the method are controlled within 0.01mm with small measurement errors and high repeatability. The dynamic test also verified the repeatability of the method in the train-running environment, and the dynamic measurement deviation of rail wear is within 0.2mm with high repeatability.

Keywords: curvature entropy, profile registration, rail wear, structured light, train-running

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Authors: Zhao Weijie, Lin Xinjian, Liu Xiaojuan, Li Lihua

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The Howland current pump is widely used in bio-impedance measurement. Much attention has been focused on the output impedance of the Howland circuit. Here we focus on the maximum load of the Howland source and discuss the relationship between the circuit parameters at maximum load. We conclude that the signal input terminal of the feedback resistor should be as large as possible, but that the current-limiting resistor should be smaller. The op-amp saturation voltage should also be high. The bandwidth of the circuit is proportional to the bandwidth of the op-amp. The Howland current pump was simulated using multisim12. When the AD8066AR was selected as the op-amp, the maximum load was 11.5 kΩ, and the Howland current pump had a stable output ipp to 2mAp up to 200 kHz. However, with an OPA847 op-amp and a load of 6.3 kΩ, the output current was also stable, and the frequency was as high as 3 MHz.

Keywords: bio-impedance, improved Howland current pump, load characteristics, bioengineering

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Authors: Risti Suryantari, Flaviana

Abstract:

The aim of this research is to design calibration method of Thermochromic Liquid Crystal for temperature distribution measurement based on mathematical morphology of hue image A glass of water is placed on the surface of sample TLC R25C5W at certain temperature. We use scanner for image acquisition. The true images in RGB format is converted to HSV (hue, saturation, value) by taking of hue without saturation and value. Then the hue images is processed based on mathematical morphology using Matlab2013a software to get better images. There are differences on the final images after processing at each temperature variation based on visualization observation and the statistic value. The value of maximum and mean increase with rising temperature. It could be parameter to identify the temperature of the human body surface like hand or foot surface.

Keywords: thermochromic liquid crystal, TLC, mathematical morphology, hue image

Procedia PDF Downloads 473

Authors: Zainab Mohammed Shukur, Najlaa Ali Alboshmina, Ali Safa Alsaegh

Abstract:

The project was investigated tribological behavior of polyether ether ketone (PEEK1000) against PEEK1000 rolling sliding (non-conformal) configuration with slip ratio 83.3%, were tested applications using a TE77 wear mechanisms and friction coefficient test rig. Under marginal lubrication conditions and the absence of film thick conditions, load 100 N was used to simulate the torque in gears 7 N.m. The friction coefficient and wear mechanisms of PEEK were studied under reciprocating roll/slide conditions with water, ethylene glycol, silicone, and base oil. Tribological tests were conducted on a TE77 high-frequency tribometer, with a disc-on-plate slide/roll (the energy pulse criterion) configuration. An Alicona G5 optical 3D micro-coordinate measurement microscope was used to investigate the surface topography and wear mechanisms. The surface roughness had been a significant effect on the friction coefficient for the PEEK/PEEK the rolling sliding contact test ethylene glycol and on the wear mechanisms. When silicone, ethylene glycol, and oil were used as a lubricant, the steady state of friction coefficient was reached faster than the other lubricant. Results describe the effect of the film thick with slip ratio of 83.3% on the tribological performance.

Keywords: polymer, rolling- sliding, energy pulse, gear contact

Procedia PDF Downloads 142

Authors: Shib Shankar Banerjeea, Andreas Ferya, Gert Heinricha, Amit Das

Abstract:

Recently, the growing need for the development of soft robots consisting of highly deformable and compliance materials emerge from the serious limitations of conventional service robots. However, one of the main challenges of soft robotics is to develop such compliance materials, which facilitates the design of soft robotic structures and, simultaneously, controls the soft-body systems, like soft artificial muscles. Generally, silicone or acrylic-based elastomer composites are used for soft robotics. However, mechanical performance and long-term reliabilities of the functional parts (sensors, actuators, main body) of the robot made from these composite materials are inferior. This work will present the development and characterization of robust super-soft programmable elastomeric materials from crosslinked natural rubber that can serve as touch and strain sensors for soft robotic arms with very high elastic properties and strain, while the modulus is altered in the kilopascal range. Our results suggest that such soft natural programmable elastomers can be promising materials and can replace conventional silicone-based elastomer for soft robotics applications.

Keywords: elastomers, soft materials, natural rubber, sensors

Procedia PDF Downloads 155

Authors: Oke Oktavianty, Tadayuki Kyoutani, Shigeyuki Haruyama, Ken Kaminishi

Abstract:

For advancing the experiment system standard of Inkjet printer that is being developed, the actual natural period, fire limitation number in droplet weight measurement and observation distance in droplet velocity measurement was investigated. In another side, the study to control the droplet volume in inkjet printer with negative actuating waveform method is still limited. Therefore, the effect of negative waveform with preliminary and suppressing vibration addition on the droplet formation process, droplet shape, volume and velocity were evaluated. The different voltage and print-head temperature were exerted to obtain the optimum preliminary and suppressing vibration. The mechanism of different phenomenon from each waveform was also discussed.

Keywords: inkjet printer, DoD, waveform, preliminary and suppressing vibration

Procedia PDF Downloads 239

Authors: B. A. Mir, A. Juneja

Abstract:

In this paper, shear behavior of reconstituted clay reinforced with varying diameter of sand compaction piles with area replacement-ratio (a_s) of 6.25, 10.24, 16, 20.25 and 64% in 100mm diameter and 200mm long clay specimens is modeled using consolidated drained and undrained triaxial tests under different confining pressures ranging from 50kPa to 575kPa. The test results show that the stress-strain behavior of the clay was highly influenced by the presence of SCP. The insertion of SCPs into soft clay has shown to have a positive effect on the load carrying capacity of the clay, resulting in a composite soil mass that has greater shear strength and improved stiffness compared to the unreinforced clay due to increased reinforcement area ratio. In addition, SCP also acts as vertical drain in the clay thus accelerating the dissipation of excess pore water pressures that are generated during loading by shortening the drainage path and activating radial drainage, thereby reducing post-construction settlement. Thus, sand compaction piles currently stand as one of the most viable and practical techniques for improving the mechanical properties of soft clays.

Keywords: reconstituted clay, SCP, shear strength, stress-strain response, triaxial tests

Procedia PDF Downloads 409