Search results for: free space optical

Authors: M. Chen, H. Lee, D. M. Weary

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China is the world’s largest egg producer, with more than 90% of production occurring in conventional cages. Cage-free housing systems offer the potential for improving hen welfare, but the growth of this system requires consumer demand, making it is important to understand consumers’ willingness to engage with cage-free eggs. Previous survey research indicates that the majority of Chinese consumers have a basic understanding of cage-free eggs and that some are willing to pay a price premium for these eggs. The aim of this research is to understand consumer behaviour, experience, and motivations when purchasing cage-free eggs in China. Purposive sampling will be used to select 20 participants from each of 2 groups: 1) consumers of cage-free eggs and 2) sales representatives who promote these eggs directly to consumers in supermarkets. This 4-month study will use methods of virtual ethnography to interact with participants repeatedly. Consumers will be asked to share their egg shopping, cooking, and eating experiences, and sales representatives will be asked to share their experiences promoting the eggs to consumers. Data collection will involve audio-recorded interviews, informal conversations (casual texts and calls), participant observation (video calling during shopping, cooking, and eating), and informant diaries (written reflections, photos, videos). All data (field notes, transcripts, diaries, photos, and videos) will be analyzed using Thematic Analysis. We expect that these will result in a nuanced understanding of consumer purchasing behaviour and motivation and will thus help identify strategies to promote higher animal welfare and cage-free egg products in China.

Keywords: animal welfare, cage-free eggs, China, consumer behaviour, ethnography

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Authors: T. H. Young, Y. J. Tsai

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A method for determining the stress distribution of a rectangular plate subjected to two pairs of arbitrarily distributed in-plane edge shear loads is proposed, and the free vibration and buckling of such a rectangular plate are investigated in this work.  The method utilizes two stress functions to synthesize the stress-resultant field of the plate with each of the stress functions satisfying the biharmonic compatibility equation. The sum of stress-resultant fields due to these two stress functions satisfies the boundary conditions at the edges of the plate, from which these two stress functions are determined. Then, the free vibration and buckling of the rectangular plate are investigated by the Galerkin method. Numerical results obtained by this work are compared with those appeared in the literature, and good agreements are observed.

Keywords: stress analysis, free vibration, plate buckling, nonuniform in-plane edge shear

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Authors: Sonia Ben Hamza, Sabra Habli, Nejla Mahjoub Said, Hervé Bournot, Georges Le Palec

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In this work, we determine the turbulent dynamic structure of pollutant dispersion in two-phase free surface flow. The numerical simulation was performed using ANSYS Fluent. The flow study is three-dimensional, unsteady and isothermal. The study area has been endowed with a rectangular obstacle to analyze its influence on the hydrodynamic variables and progression of the pollutant. The numerical results show that the hydrodynamic model provides prediction of the dispersion of a pollutant in an open channel flow and reproduces the recirculation and trapping the pollutant downstream near the obstacle.

Keywords: CFD, free surface, polluant dispersion, turbulent flows

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Authors: Seyedeh Mozhgan Seyed-Talebi, Weng-Kent Chan, Hsin-Yi Tiffany Chen

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Lead-free perovskite photovoltaic (PV) technology employing non-toxic tin halide perovskite absorbers is pivotal for advancing perovskite solar cell (PSC) commercialization. Despite challenges posed by perovskite sensitivity to oxygen and humidity, our study utilizes DFT calculations using VASP and NanoDCAL software and SCAPS-1D simulations to elucidate the charge transport mechanism at the interface of CsSnI₃-FASnI₃ heterojunction. Results reveal how inherent electric fields facilitate efficient carrier transport, reducing recombination losses. We predict optimized power conversion efficiencies (PCEs) and highlight the potential of CsSnI3-FASnI3 heterojunctions for cost-effective and efficient charge transport layer-free (CTLF) photovoltaic devices. Our study provides insights into the future direction of recognizing more efficient, nontoxic heterojunction perovskite devices.

Keywords: charge transport layer free, CsSnI₃-FASnI₃ heterojunction, lead-free perovskite solar cell, tin halide perovskite., Charge transport layer free

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Authors: Angel Pérez Sánchez

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In 1929, a light redshift was discovered in distant galaxies and was interpreted as produced by galaxies moving away from each other at high speed. This interpretation led to the consideration of a new source of energy, which was called Dark Energy. Redshift is a loss of light wave frequency produced by galaxies moving away at high speed, but the loss of frequency can also be produced by the friction of light waves on their way to Earth. This friction is impossible because outer space is empty, but if it were not empty and a medium existed in this empty space, it would be possible. The consequences would be extraordinary because Universe acceleration and Dark Energy would be in doubt. This article presents evidence that empty space is actually a medium occupied by different particles, among them the most significant would-be Graviton or Higgs Boson, because let's not forget that gravity also affects empty space.

Keywords: Big Bang, dark energy, doppler effect, redshift, starlight frequency reduction, universe acceleration

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Authors: O. Hinrichs, H. Franz, G. Reiter

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Electron guns have a key function in a series of thermal processes, like EB (electron beam) melting, evaporation or welding. These techniques need a high-intensity continuous electron beam that defocuses itself due to high space charge forces. A proper beam transport throughout the magnetic focusing system can be ensured by a space charge compensation via residual gas ions. The different pressure stages in the EB gun cause various degrees of compensation. A numerical model was installed to simulate realistic charge distributions within the beam by using CST-Particle Studio code. We will present current status of beam dynamic simulations. This contribution will focus on the creation of space charge ions and their influence on beam and gun components. Furthermore, the beam transport in the gun will be shown for different beam parameters. The electron source allows to produce beams with currents of 3 A to 15 A and energies of 40 keV to 45 keV.

Keywords: beam dynamic simulation, space charge compensation, thermionic electron source, EB melting, EB thermal processing

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Authors: Dumont Maxime, Correia Carlos, Sauvage Jean-François, Schwartz Noah, Gray Morgan

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Context: The concept of the segmented telescope is unavoidable to build extremely large telescopes (ELT) in the quest for spatial resolution, but it also allows one to fit a large telescope within a reduced volume of space (JWST) or into an even smaller volume (Standard Cubesat). Cubesats have tight constraints on the computational burden available and the small payload volume allowed. At the same time, they undergo thermal gradients leading to large and evolving optical aberrations. The pupil segmentation comes nevertheless with an obvious difficulty: to co-phase the different segments. The CubeSat constraints prevent the use of a dedicated wavefront sensor (WFS), making the focal-plane images acquired by the science detector the most practical alternative. Yet, one of the challenges for the wavefront sensing is the non-linearity between the image intensity and the phase aberrations. Plus, for Earth observation, the object is unknown and unrepeatable. Recently, several studies have suggested Neural Networks (NN) for wavefront sensing; especially convolutional NN, which are well known for being non-linear and image-friendly problem solvers. Aims: We study in this paper the prospect of using NN to measure the phasing aberrations of a segmented pupil from the focal-plane image directly without a dedicated wavefront sensing. Methods: In our application, we take the case of a deployable telescope fitting in a CubeSat for Earth observations which triples the aperture size (compared to the 10cm CubeSat standard) and therefore triples the angular resolution capacity. In order to reach the diffraction-limited regime in the visible wavelength, typically, a wavefront error below lambda/50 is required. The telescope focal-plane detector, used for imaging, will be used as a wavefront-sensor. In this work, we study a point source, i.e. the Point Spread Function [PSF] of the optical system as an input of a VGG-net neural network, an architecture designed for image regression/classification. Results: This approach shows some promising results (about 2nm RMS, which is sub lambda/50 of residual WFE with 40-100nm RMS of input WFE) using a relatively fast computational time less than 30 ms which translates a small computation burder. These results allow one further study for higher aberrations and noise.

Keywords: wavefront sensing, deep learning, deployable telescope, space telescope

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Authors: A. V. Shelke, P. S. More

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This research aimed to study the kinetic reaction of reused cooking oil and to find the optimum condition of its process. The feedstock was collected from the street sellers and also prepared at laboratory. From this research, it is found that the kinetic reaction of reused sunflower oil (auto-oxidation) is obtained in terms of variation of the absorption coefficient of unexposed sunflower oil as 0.05 which is very close to that of exposed sunflower oil 0.075. At room temperature, the optimum intensity obtained from optical absorption spectroscopy study is 0.267 for unexposed sunflower oil and 0.194 for exposed sunflower oil. However, results indicated that FTIR spectroscopy is accurate and precise enough for such determination. Free Fatty Acid (FFA% = 026), acid ~53% and safonication ~%192 get reduce in exposed oil was investigated.

Keywords: friction, oxidation, sunflower oil, vegetable oils

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Authors: S. M. AL-Shomar, N. B. Ibrahim, Sahrim Hj. Ahmad

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ZnO thin films with various Gd doping concentration (0, 0.01, 0.03 and 0.05 mol/L) have been synthesized by sol–gel method on quartz substrates at annealing temperature of 600 ºC. X-ray analysis reveals that ZnO(Gd) films have hexagonal wurtzite structure. No peaks that correspond to Gd metal clusters or gadolinium acetylacetonate are detected in the patterns. The position of the main peak (101) shifts to higher angles after doping. The surface morphologies studied using a field emission scanning electron microscope (FESEM) showed that the grain size and the films thickness reduced gradually with the increment of Gd concentration. The roughness of ZnO film investigated by an atomic force microscopy (AFM) showed that the films are smooth and high dense grain. The roughness of doped films decreased from 6.05 to 4.84 rms with the increment of dopant concentration.The optical measurements using a UV-Vis-NIR spectroscopy showed that the Gd doped ZnO thin films have high transmittance (above 80%) in the visible range and the optical band gap increase with doping concentration from 3.13 to 3.39 eV. The doped films show low electrical resistivity 2.6 × 10-3Ω.cm.at high doping concentration.

Keywords: Gd doped ZnO, electric, optics, microstructure

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Authors: Shivani Singla, Om Prakash Pandey, Gopi Sharma

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Metallic nanoparticle doped glasses has lead to rapid development in the field of optics. Large third order non-linearity, ultrafast time response, and a wide range of resonant absorption frequencies make these metallic nanoparticles more important in comparison to their bulk material. All these properties are highly dependent upon the size, shape, and surrounding environment of the nanoparticles. In a quest to find a suitable material for optical applications, several efforts have been devoted to improve the properties of such glasses in the past. In the present study, bismuth borate glass doped with different size gold nanoparticles (AuNPs) has been prepared using the conventional melt-quench technique. Synthesized glasses are characterized by X-ray diffraction (XRD) and Fourier Transformation Infrared spectroscopy (FTIR) to observe the structural modification in the glassy matrix with the variation in the size of the AuNPs. Glasses remain purely amorphous in nature even after the addition of AuNPs, whereas FTIR proposes that the main structure contains BO₃ and BO₄ units. Field emission scanning electron microscopy (FESEM) confirms the existence and variation in the size of AuNPs. Differential thermal analysis (DTA) depicts that prepared glasses are thermally stable and are highly suitable for the fabrication of optical fibers. The nonlinear optical parameters (nonlinear absorption coefficient and nonlinear refractive index) are calculated out by using the Z-scan technique with a Ti: sapphire laser at 800 nm. It has been concluded that the size of the nanoparticles highly influences the structural thermal and optical properties system.

Keywords: bismuth borate glass, different size, gold nanoparticles, nonlinearity

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Authors: Imen Debbabi, Hédi BelHadjSalah

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The Improved Element Free Galerkin (IEFG) method is presented to treat the steady states and the transient heat transfer problems. As a result of a combination between the Improved Moving Least Square (IMLS) approximation and the Element Free Galerkin (EFG) method, the IEFG's shape functions don't have the Kronecker delta property and the penalty method is used to impose the Dirichlet boundary conditions. In this paper, two heat transfer problems, transient and steady states, are studied to improve the efficiency of this meshfree method for 2D heat transfer problems. The performance of the IEFG method is shown using the comparison between numerical and analytic results.

Keywords: meshfree methods, the Improved Moving Least Square approximation (IMLS), the Improved Element Free Galerkin method (IEFG), heat transfer problems

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Authors: Parvathy Anitha, Nilesh J. Vasa, M. S. Ramachandra Rao

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ZnO is a semiconducting material with a direct wide band gap of 3.37 eV and a large exciton binding energy of 60 meV at room temperature. Microspheres with high sphericity and symmetry exhibit unique functionalities which makes them excellent omnidirectional optical resonators. Hence there is an advent interest in fabrication of single crystalline semiconductor microspheres especially magnetic ZnO microspheres, as ZnO is a promising material for semiconductor device applications. Also, ZnO is non-toxic and biocompatible, implying it is a potential material for biomedical applications. Room temperature Photoluminescence (PL) spectra of the fabricated ZnO microspheres were measured, at an excitation wavelength of 325 nm. The ultraviolet (UV) luminescence observed is attributed to the room-temperature free exciton related near-band-edge (NBE) emission in ZnO. Besides the NBE luminescence, weak and broad visible luminescence (~560nm) was also observed. This broad emission band in the visible range is associated with oxygen vacancies related to structural defects. In transition metal (TM) ion-doped ZnO, 3d levels emissions of TM ions will modify the inherent characteristic emissions of ZnO. A micron-sized ZnO crystal has generally a wurtzite structure with a natural hexagonal cross section, which will serve as a WGM (whispering gallery mode) lasing micro cavity due to its high refractive index (~2.2). But hexagonal cavities suffers more optical loss at their corners in comparison to spherical structures; hence spheres may be a better candidate to achieve effective light confinement. In our study, highly smooth spherical shaped micro particles with different diameters ranging from ~4 to 6 μm were grown on different substrates. SEM (Scanning Electron Microscopy) and AFM (Atomic Force Microscopy) images show the presence of uniform smooth surfaced spheres. Raman scattering measurements from the fabricated samples at 488 nm light excitation provide convincing supports for the wurtzite structure of the prepared ZnO microspheres. WGM lasing studies from TM-doped ZnO microparticles are in progress.

Keywords: laser ablation, microcavity, photoluminescence, ZnO microsphere

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Authors: Tayebeh Sahraeibelverdi, Ahmad Shirazi Hadi Veladi, Mazdak Radmalekshah

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Optical sensors became attractive due to preciseness, low power consumption, and intrinsic electromagnetic interference-free characteristic. Among the waveguide optical sensors, cavity-based ones attended for the high Q-factor. Micro ring resonators as a potential platform have been investigated for various applications as biosensors to pressure sensors thanks to their sensitive ring structure responding to any small change in the refractive index. Furthermore, these small micron size structures can come in an array, bringing the opportunity to have any of the resonance in a specific wavelength and be addressed in this way. Another exciting application is applying a strain to the ring and making them an optical strain gauge where the traditional ones are based on the piezoelectric material. Making them in arrays needs electrical wiring and about fifty times bigger in size. Any physical element that impacts the waveguide cross-section, Waveguide elastic-optic property change, or ring circumference can play a role. In comparison, ring size change has a larger effect than others. Here an engineered ring structure is investigated to study the strain effect on the ring resonance wavelength shift and its potential for more sensitive strain devices. At the same time, these devices can measure any strain by mounting on the surface of interest. The idea is to change the" O" shape ring to a "C" shape ring with a small opening starting from 2π/360 or one degree. We used the Mode solution of Lumbrical software to investigate the effect of changing the ring's opening and the shift induced by applied strain. The designed ring radius is a three Micron silicon on isolator ring which can be fabricated by standard complementary metal-oxide-semiconductor (CMOS) micromachining. The measured wavelength shifts from1-degree opening of the ring to a 6-degree opening have been investigated. Opening the ring for 1-degree affects the ring's quality factor from 3000 to 300, showing an order of magnitude Q-factor reduction. Assuming a strain making the ring-opening from 1 degree to 6 degrees, our simulation results showing negligible Q-factor reduction from 300 to 280. A ring resonator quality factor can reach up to 108 where an order of magnitude reduction is negligible. The resonance wavelength shift showed a blue shift and was obtained to be 1581, 1579,1578,1575nm for 1-, 2-, 4- and 6-degree ring-opening, respectively. This design can find the direction of the strain-induced by applying the opening on different parts of the ring. Moreover, by addressing the specified wavelength, we can precisely find the direction. We can open a significant opportunity to find cracks and any surface mechanical property very specifically and precisely. This idea can be implemented on polymer ring resonators while they can come with a flexible substrate and can be very sensitive to any strain making the two ends of the ring in the slit part come closer or further.

Keywords: optical ring resonator, strain gauge, strain sensor, surface mechanical property analysis

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Authors: Hoang Van Ngoc, Nguyen Vu Nhan, Nguyen Quang Bau

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The light-effect in cylindrical quantum wire with an infinite potential for the case of electrons, optical phonon scattering, is studied based on the quantum kinetic equation. The density of the direct current in a cylindrical quantum wire by a linearly polarized electromagnetic wave, a DC electric field, and an intense laser field is calculated. Analytic expressions for the density of the direct current are studied as a function of the frequency of the laser radiation field, the frequency of the linearly polarized electromagnetic wave, the temperature of system, and the size of quantum wire. The density of the direct current in cylindrical quantum wire with an infinite potential for the case of electrons – optical phonon scattering is nonlinearly dependent on the frequency of the linearly polarized electromagnetic wave. The analytic expressions are numerically evaluated and plotted for a specific quantum wire, GaAs/GaAsAl.

Keywords: the light–effect, cylindrical quantum wire with an infinite potential, the density of the direct current, electrons-optical phonon scattering

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Authors: Juanee Cilliers

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Urban citizens have come to expect more from their cities, demanding optimal conditions for business creativity and professional development, along with efficient, sustainable transportation and energy systems that feed robust economic development and healthy job markets. Urban public spaces are an important part of the urban environment, creating the framework for public life and quality thereof. The transformation of space into successful public places are crucial in this regard as planning must safeguard flexibility towards future changes, whilst simultaneously be capable of acting on short-term demands in order to address the complexity of public spaces within urban areas. This research evaluated two case studies of different cities in Belgium which successfully transformed spaces into lively public places. The transformation was illustrated and evaluated by means of visual analyses and space usage analyses of the original and redesigned space, along with the experience and value that the redesign brought to the area. Selected design elements were identified and evaluated based on the role in the transformation process, in an attempt to draw conclusions with regards to theory-practice relevance and to guide the transformation of space to place of (similar) public spaces.

Keywords: space, place, transformation, case studies

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Authors: Yu-Hsi Huang, Ying-Der Tsai

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Piezoelectric circular plates can provide out-of-plane vibrational displacements on low frequency and in-plane vibrational displacements on high frequency. Piezoelectric semi-spherical shell, which is double-curvature structure, can induce three-dimensional vibrational displacements over a large frequency range. In this study, three-dimensional vibrational characteristics of piezoelectric semi-spherical shells with free boundary conditions are investigated using three experimental methods and finite element numerical modeling. For the experimental measurements, amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) is used to obtain resonant frequencies and radial and azimuthal mode shapes. This optical technique utilizes a full-field and non-contact optical system that measures both the natural frequency and corresponding vibration mode shape simultaneously in real time. The second experimental technique used, laser displacement meter is a point-wise displacement measurement method that determines the resonant frequencies of the piezoelectric shell. An impedance analyzer is used to determine the in-plane resonant frequencies of the piezoelectric semi-spherical shell. The experimental results of the resonant frequencies and mode shapes for the piezoelectric shell are verified with the result from finite element analysis. Excellent agreement between the experimental measurements and numerical calculation is presented on the three-dimensional vibrational characteristics of the piezoelectric semi-spherical shell.

Keywords: piezoelectric semi-spherical shell, mode shape, resonant frequency, electronic speckle pattern interferometry, radial vibration, azimuthal vibration

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Authors: Tibor Ajtai, Noémi Utry, Máté Pintér, Tomi Smausz, Zoltán Kónya, Béla Hopp, Gábor Szabó, Zoltán Bozóki

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Characterization of spectral responses of light absorbing carbonaceous particulate matter (LAC) is of great importance in both modelling its climate effect and interpreting remote sensing measurement data. The residential or domestic combustion of coal is one of the dominant LAC constituent. According to some related assessments the residential coal burning account for roughly half of anthropogenic BC emitted from fossil fuel burning. Despite of its significance in climate the comprehensive investigation of optical properties of residential coal aerosol is really limited in the literature. There are many reason of that starting from the difficulties associated with the controlled burning conditions of the fuel, through the lack of detailed supplementary proximate and ultimate chemical analysis enforced, the interpretation of the measured optical data, ending with many analytical and methodological difficulties regarding the in-situ measurement of coal aerosol spectral responses. Since the gas matrix of ambient can significantly mask the physicochemical characteristics of the generated coal aerosol the accurate and controlled generation of residential coal particulates is one of the most actual issues in this research area. Most of the laboratory imitation of residential coal combustion is simply based on coal burning in stove with ambient air support allowing one to measure only the apparent spectral feature of the particulates. However, the recently introduced methodology based on a laser ablation of solid coal target opens up novel possibilities to model the real combustion procedure under well controlled laboratory conditions and makes the investigation of the inherent optical properties also possible. Most of the methodology for spectral characterization of LAC is based on transmission measurement made of filter accumulated aerosol or deduced indirectly from parallel measurements of scattering and extinction coefficient using free floating sampling. In the former one the accuracy while in the latter one the sensitivity are liming the applicability of this approaches. Although the scientific community are at the common platform that aerosol-phase PhotoAcoustic Spectroscopy (PAS) is the only method for precise and accurate determination of light absorption by LAC, the PAS based instrumentation for spectral characterization of absorption has only been recently introduced. In this study, the investigation of the inherent, spectral features of laser generated and chemically characterized residential coal aerosols are demonstrated. The experimental set-up and its characteristic for residential coal aerosol generation are introduced here. The optical absorption and the scattering coefficients as well as their wavelength dependency are determined by our state-of-the-art multi wavelength PAS instrument (4λ-PAS) and multi wavelength cosinus sensor (Aurora 3000). The quantified wavelength dependency (AAE and SAE) are deduced from the measured data. Finally, some correlation between the proximate and ultimate chemical as well as the measured or deduced optical parameters are also revealed.

Keywords: absorption, scattering, residential coal, aerosol generation by laser ablation

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Authors: J. Prathap Kumar, G. Vaitheeswaran

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The present study investigates the role of ammonium and potassium ion in the electronic, bonding and optical properties of dinitramide salts due to their stability and non-toxic nature. A detailed analysis of bonding between NH₄ and K with dinitramide, optical transitions from the valence band to the conduction band, absorption spectra, refractive indices, reflectivity, loss function are reported. These materials are well known as oxidizers in solid rocket propellants. In the present work, we use full potential linear augmented plane wave (FP-LAPW) method which is implemented in the Wien2k package within the framework of density functional theory. The standard DFT functional local density approximation (LDA) and generalized gradient approximation (GGA) always underestimate the band gap by 30-40% due to the lack of derivative discontinuities of the exchange-correlation potential with respect to an occupation number. In order to get reliable results, one must use hybrid functional (HSE-PBE), GW calculations and Tran-Blaha modified Becke-Johnson (TB-mBJ) potential. It is very well known that hybrid functionals GW calculations are very expensive, the later methods are computationally cheap. The new developed TB-mBJ functionals use information kinetic energy density along with the charge density employed in DFT. The TB-mBJ functionals cannot be used for total energy calculations but instead yield very much improved band gap. The obtained electronic band gap at gamma point for both the ammonium dinitramide and potassium dinitramide are found to be 2.78 eV and 3.014 eV with GGA functional, respectively. After the inclusion of TB-mBJ, the band gap improved by 4.162 eV for potassium dinitramide and 4.378 eV for ammonium dinitramide. The nature of the band gap is direct in ADN and indirect in KDN. The optical constants such as dielectric constant, absorption, and refractive indices, birefringence values are presented. Overall as there are no experimental studies we present the improved band gap with TB-mBJ functional following with optical properties.

Keywords: ammonium dinitramide, potassium dinitramide, DFT, propellants

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Authors: Tao Lin, Shanghong Zhao, Yufu Yin, Zihang Zhu, Wei Jiang, Xuan Li, Qiurong Zheng

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A simple operated, stable and compact multi-band frequency conversion and multi-phase shift is proposed to satisfy the demands of multi-band communication and radar phase array system. The dual polarization quadrature phase shift keying (DP-QPSK) modulator is employed to support the LO sideband and the optical frequency comb simultaneously. Meanwhile, the fiber is also used to introduce different phase shifts to different sidebands. The simulation result shows that by controlling the DC bias voltages and a C band microwave signal with frequency of 4.5 GHz can be simultaneously converted into other signals that cover from C band to K band with multiple phases. It also verifies that the multi-band and multi-phase frequency conversion system can be stably performed based on current manufacturing art and can well cope with the DC drifting. It should be noted that the phase shift of the converted signal also partly depends of the length of the optical fiber.

Keywords: microwave photonics, multi-band frequency conversion, multi-phase shift, conversion efficiency

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Authors: R. Chanajaree, D. Luanwiset, K. Pongpratea

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Dye removal is an environmental concern because the textile industries have been increasing by world population and industrialization. Adsorption is the technique to find adsorbents to remove dyes from wastewater. This method is low-cost and effective for dye removal. This work tries to develop effective adsorbents using the computational approach because it will be able to predict the possibility of the adsorbents for specific dyes in terms of binding free energies. The computational approach is faster and cheaper than the experimental approach in case of finding the best adsorbents. All starting structures of dyes and adsorbents are optimized by quantum calculation. The complexes between dyes and adsorbents are generated by the docking method. The obtained binding free energies from docking are compared to binding free energies from the experimental data. The calculated energies can be ranked as same as the experimental results. In addition, this work also shows the possible orientation of the complexes. This work used two experimental groups of the complexes of the dyes and adsorbents. In the first group, there are chitosan (adsorbent) and two dyes (reactive red (RR) and direct sun yellow (DY)). In the second group, there are poly(1,2-epoxy-3-phenoxy) propane (PEPP), which is the adsorbent, and 2 dyes of bromocresol green (BCG) and alizarin yellow (AY).

Keywords: dyes removal, binding free energies, quantum calculation, docking

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Authors: Anika Zafiah M. Rus, Nur Munirah Abdullah, M. F. L. Abdullah

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The fabrication and characterization of composite films of graphite- bioepoxy is described. Free-standing thin films of ~0.1 mm thick are prepared using a simple solution mixing with mass proportion of 7/3 (bioepoxy/graphite) and drop casting at room temperature. Fourier transform infra-red spectroscopy (FTIR) and Ultraviolet-visible (UV-vis) spectrophotometer are performed to evaluate the changes in chemical structure and adsorption spectra arising with the increasing of graphite weight loading (wt.%) into the biopolymer matrix. The morphologic study shows a homogeneously dispersed and strong particle bonding between the graphite and the bioepoxy, with conductivity of the film 103 S/m, confirming the efficiency of the processes.

Keywords: absorbance peak, biopolymer, graphite- bioepoxy composites, particle bonding

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Authors: Mclee Kerolle

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For more than 50 years, the state of Hawaii has had the beginnings of a burgeoning commercial aerospace presence statewide. While Hawaii provides the aerospace industry with unique assets concerning geographic location, lack of range safety issues and other factors critical to aerospace development, Hawaii’s strategy and commitment for aerospace have been unclear. For this reason, this paper presents a comparative analysis of Hawaii’s space sector with two of the world’s leading space sectors, Colorado and the Netherlands, in order to provide a strategic plan that establishes a firm position going forward to support Hawaii’s aerospace development statewide. This plan will include financial and other economic incentives legislatively supported by the State to help grow and diversify Hawaii’s aerospace sector. The first part of this paper will examine the business model adopted by the Colorado Space Coalition (CSC), a group of industry stakeholders working to make Colorado a center of excellence for aerospace, as blueprint for growth in Hawaii’s space sector. The second section of this paper will examine the business model adopted by the Netherlands Space Business Incubation Centre (NSBIC), a European Space Agency (ESA) affiliated program that offers business support for entrepreneurs to turn space-connected business ideas into commercial companies. This will serve as blueprint to incentivize space businesses to launch and develop in Hawaii. The third section of this paper will analyze the current policies both CSC, and NSBIC implores to promote industry expansion and legislative advocacy. The final section takes the findings from both space sectors and applies their most adaptable features to a Hawaii specific space business model that takes into consideration the unique advantage and disadvantages found in developing Hawaii’s space sector. The findings of this analysis will show that the development of a strategic plan based on a comparative analysis that creates high technology jobs and new pathways for a trained workforce in the space sector, as well as elicit state support and direction, will achieve the goal of establishing Hawaii as a center of space excellence. This analysis will also serve as a signal to the federal, private sector and international community that Hawaii is indeed serious about developing its’ aerospace industry. Ultimately this analysis and subsequent aerospace development plan will serve as a blueprint for the benefit of all space-faring nations seeking to develop their space sectors.

Keywords: Colorado, Hawaii, Netherlands, space policy

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Authors: Hamid Merzouk, D. T. Talantikite, H. Haddad, Amel Tounsi

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ZnS is an important II-VI binary compound with large band-gap energy at room temperature. We present in this work preparation and characterization of ZnS and Cu doped ZnS thin films. The depositions are performed by a simple chemical bath deposition route. Structural properties are carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Optical transmittance is investigated by the UV-visible spectroscopy at room temperature.

Keywords: chemical, bath, method, Cu, doped, ZnS, thin, films

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Authors: Qusay Alghazali, Tibor Cinkler, Abdulhalim Fayad

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In modern optical networks, the flex grid spectrum usage is most widespread, where higher bit rate streams get larger spectrum slices while lower bit rate traffic streams get smaller spectrum slices. To our practice, under the ITU-T recommendation, G.694.1, spectrum slices of 50, 75, and 100 GHz are being used with central frequency at 193.1 THz. However, when these spectrum slices are not sufficient, multiple spectrum slices can use either one next to another or anywhere in the optical wavelength. In this paper, we propose the analysis of the wavelength assignment problem. We compare different algorithms for this spectrum assignment with and without protection. As a reference for comparisons, we concluded that the Integer Linear Programming (ILP) provides the global optimum for all cases. The most scalable algorithm is the greedy one, which yields results in subsequent ranges even for more significant network instances. The algorithms’ benchmark implemented using the LEMON C++ optimization library and simulation runs based on a minimum number of spectrum slices assigned to lightpaths and their execution time.

Keywords: spectrum assignment, integer linear programming, greedy algorithm, international telecommunication union, library for efficient modeling and optimization in networks

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Authors: Anurag Sharma, Manoj Kumar, Ashima, Sooraj Parkash

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The work in this paper presents simulative comparison for different modulation formats such as NRZ, Manchester and CRZ in a 100 subscribers at 5 Gbps bit rate Gigabit Ethernet Passive Optical Network (GEPON) FTTH network. It is observed from the simulation results that the CRZ modulation format is best suited for the designed system. A link design for 1:100 splitter is used as Passive Optical Network (PON) element which creates communication between central offices to different users. The Bit Error Rate (BER) is found to be 2.8535e-10 at 5 Gbit/s systems for CRZ modulation format.

Keywords: PON , FTTH, OLT, ONU, CO, GEPON

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Authors: C. Busuioc, S. I. Jinga, E. Pavel

Abstract:

The continuous need of more non-volatile memories with a higher storage capacity, smaller dimensions and weight, as well as lower costs, has led to the exploration of optical lithography on active media, as well as patterned magnetic composites. In this context, optical lithography is a technique that can provide a significant decrease of the information bit size to the nanometric scale. However, there are some restrictions that arise from the need of breaking the optical diffraction limit. Major achievements have been obtained by employing a vitoceramic material as active medium and a laser beam operated at low power for the direct writing procedure. Thus, optical discs with ultra-high density were fabricated by a conventional melt-quenching method starting from analytical purity reagents. They were subsequently used for 3D recording based on their photosensitive features. Naturally, the next step consists in the elucidation of the composition and structure of the active centers, in correlation with the use of silver and rare-earth compounds for the synthesis of the optical supports. This has been accomplished by modern characterization methods, namely transmission electron microscopy coupled with selected area electron diffraction, scanning transmission electron microscopy and electron energy loss spectroscopy. The influence of laser diode parameters, silver concentration and fluorescent compounds formation on the writing process and final material properties was investigated. The results indicate performances in terms of capacity with two order of magnitude higher than other reported information storage systems. Moreover, the fluorescent photosensitive vitroceramics may be integrated in other applications which appeal to nanofabrication as the driving force in electronics and photonics fields.

Keywords: data storage, fluorescent compounds, laser writing, vitroceramics

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Authors: Han Xiao, Zhang Lei, Huang Hai, Lv Shizeng

Abstract:

Space environment simulator is a device for spacecraft test. KM8 large space environment simulator built in Tianjing Space City is the largest as well as the most advanced space environment simulator in China. Large deviation of spacecraft level will lead to abnormally work of the thermal control device in spacecraft during the thermal vacuum test. In order to avoid thermal vacuum test failure, level adjusting mechanism system is developed in the KM8 large space environment simulator as one of the most important subsystems. According to the level adjusting requirements of spacecraft’s thermal vacuum tests, the four fulcrums adjusting model is established. By means of collecting level instruments and displacement sensors data, stepping motors controlled by PLC drive four supporting legs simultaneous movement. In addition, a PID algorithm is used to control the temperature of supporting legs and level instruments which long time work under the vacuum cold and black environment in KM8 large space environment simulator during thermal vacuum tests. Based on the above methods, the data acquisition and processing, the analysis and calculation, real time adjustment and fault alarming of the level adjusting mechanism system are implemented. The level adjusting accuracy reaches 1mm/m, and carrying capacity is 20 tons. Debugging showed that the level adjusting mechanism system of KM8 large space environment simulator can meet the thermal vacuum test requirement of the new generation spacecraft. The performance and technical indicators of the level adjusting mechanism system which provides important support for the development of spacecraft in China have been ahead of similar equipment in the world.

Keywords: space environment simulator, thermal vacuum test, level adjusting, spacecraft, parallel mechanism

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Authors: Mildred Moreno Villanueva

Abstract:

Public space is essential to strengthen the social and urban fabric and the social cohesion; there lies the importance of its study. Hence, the aim of this paper is to analyze the quality of public space in the XXI century in both quantitative and qualitative terms. In this article, the concept of public space includes open spaces such as parks, public squares and walking areas. To make this analysis we take Mexico City as the case study. It has a population of nearly 9 million inhabitants and it is composed of sixteen boroughs. For this analysis, we consider both, existing public spaces and the government intervention for building and improvement of new and existent public spaces. Results show that on the one hand, quantitatively there is not an equitable distribution of public spaces because of both, the growth of the city itself, as well as for the absence of political will to create public spaces. Another factor is the evolution of this city, which has been growing merely in a 'patched pattern', where public space has played no role at all with a total absence of urban design. On the other hand, qualitatively, even the boroughs with the most public spaces have not shown interest in making these spaces qualitatively inclusive and open to the general population aiming for integration. Therefore, urban projects that privatize public space seem to be the rule, rather than a rehabilitation effort of the existent public spaces. Hence, state intervention should reinforce its role as an agent of social change acting in the benefit of the majority of the inhabitants with the promotion of more inclusive public spaces.

Keywords: exclusion, inclusion, Mexico City, public space

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Authors: C. Babu Rao, Pandian Chelliah

Abstract:

Owing to their reliability, a number of fluorescent spectra based fiber optic sensors have been developed for detection and identification of hazardous chemicals such as explosives, narcotics etc. In High security regions, such as airports, it is important to monitor simultaneously multiple locations. This calls for deployment of a portable sensor at each location. However, the selectivity and sensitivity of these techniques depends on the spectral resolution of the spectral analyzer. The better the resolution the larger the repertoire of chemicals that can be detected. A portable unit will have limitations in meeting these requirements. Optical fibers can be employed for collecting and transmitting spectral signal from the portable sensor head to a sensitive central spectral analyzer (CSA). For multipoint sensing, optical multiplexing of multiple sensor heads with CSA has to be adopted. However with multiplexing, when one sensor head is connected to CSA, the rest may remain unconnected for the turn-around period. The larger the number of sensor heads the larger this turn-around time will be. To circumvent this imitation, we propose in this paper, an optical encoding methodology to use multiple portable sensor heads connected to a single CSA. Each portable sensor head is assigned an unique address. Spectra of every chemical detected through this sensor head, are encoded by its unique address and can be identified at the CSA end. The methodology proposed is demonstrated through a simulation using Matlab SIMULINK.

Keywords: optical encoding, fluorescence, multipoint sensing

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Authors: Halima Albalushi, Mohadese Boroojerdi, Murtadha Alkhabori

Abstract:

Introduction: Maintenance of stem cell properties during culture necessitates the recreation of the natural cell niche. Studies reported the promising outcome of mesenchymal stem cells (MSC) properties maintenance after using extracellular matrix such as CELLstart™, which is the recommended coating material for stem cells cultured in serum-free and xeno-free conditions. Laminin-521 is known as a crucial adhesion protein, which is found in natural stem cell niche, and plays an important role in facilitating the maintenance of self-renewal, pluripotency, standard morphology, and karyotype of human pluripotent stem cells (PSCs). The aim of this study is to investigate the effects of Laminin-521 on human umbilical cord-derived mesenchymal stem cells (UC-MSC) characteristics as a step toward clinical application. Methods: Human MSC were isolated from the umbilical cord via the explant method. Umbilical cord-derived-MSC were cultured in serum-free and xeno-free conditions in the presence of Laminin-521 for six passages. Cultured cells were evaluated by morphology and expansion index for each passage. Phenotypic characterization of UC-MSCs cultured on Laminin-521 was evaluated by assessment of cell surface markers. Results: Umbilical cord derived-MSCs formed small colonies and expanded as a homogeneous monolayer when cultured on Laminin-521. Umbilical cord derived-MSCs reached confluence after 4 days in culture. No statistically significant difference was detected in all passages when comparing the expansion index of UC-MSCs cultured on LN-521 and CELLstart™. Phenotypic characterization of UC-MSCs cultured on LN-521 using flow cytometry revealed positive expression of CD73, CD90, CD105 and negative expression of CD34, CD45, CD19, CD14 and HLA-DR.Conclusion: Laminin-521 is comparable to CELLstart™ in supporting UC-MSCs expansion and maintaining their characteristics during culture in xeno-free and serum-free culture conditions.

Keywords: mesenchymal stem cells, culture, laminin-521, xeno-free serum-free

Procedia PDF Downloads 52