Search results for: optical fiber glass

Authors: Selami Şahin

Abstract:

In this paper, in order to achieve sufficient bit error rate (BER) according to zenith angle of the satellite to ground station, SNR requirement is investigated utilizing pulse position modulation (PPM). To realize explicit results, all parameters such as link distance, Rytov variance, scintillation index, wavelength, aperture diameter of the receiver, Fried's parameter and zenith angle have been taken into account. Results indicate that after some parameters are determined since the constraints of the system, to achieve desired BER, required SNR values are in wide range while zenith angle changes from small to large values. Therefore, in order not to utilize high link margin, either SNR should adjust according to zenith angle or link should establish with predetermined intervals of the zenith angle.

Keywords: Free-space optical communication, optical downlink channel, atmospheric turbulence, wireless optical communication

Procedia PDF Downloads 402

Authors: Smita Pallavi, Raj Ratn Pranesh, Sumit Kumar

Abstract:

Information representation as tables is compact and concise method that eases searching, indexing, and storage requirements. Extracting and cloning tables from parsable documents is easier and widely used; however, industry still faces challenges in detecting and extracting tables from OCR (Optical Character Recognition) documents or images. This paper proposes an algorithm that detects and extracts multiple tables from OCR document. The algorithm uses a combination of image processing techniques, text recognition, and procedural coding to identify distinct tables in the same image and map the text to appropriate the corresponding cell in dataframe, which can be stored as comma-separated values, database, excel, and multiple other usable formats.

Keywords: table extraction, optical character recognition, image processing, text extraction, morphological transformation

Procedia PDF Downloads 145

Authors: Walid Tawfik

Abstract:

The interaction of high intensity ultrashort laser pulses with plasma generates many significant applications, including soft x-ray lasers, time-resolved laser induced plasma spectroscopy LIPS, and laser-driven accelerators. The development in producing of femtosecond down to ten femtosecond optical pulses has facilitates scientists with a vital tool in a variety of ultrashort phenomena, such as high field physics, femtochemistry and high harmonic generation HHG. In this research, we generate a two-octave-wide ultrashort supercontinuum pulses with an optical spectrum extending from 3.5 eV (ultraviolet) to 1.3 eV (near-infrared) using a capillary fiber filled with neon gas. These pulses are formed according to nonlinear self-phase modulation in the neon gas as a nonlinear medium. The investigations of the created pulses were made using spectral phase interferometry for direct electric-field reconstruction (SPIDER). A complete description of the output pulses was considered. The observed characterization of the produced pulses includes the beam profile, the pulse width, and the spectral bandwidth. After reaching optimization conditions, the intensity of the reconstructed pulse autocorrelation function was applied for the shorts pulse duration to achieve transform limited ultrashort pulses with durations below 6-fs energies up to 600μJ. Moreover, the effect of neon pressure variation on the pulse width was examined. The nonlinear self-phase modulation realized to be increased with the pressure of the neon gas. The observed results may lead to an advanced method to control and monitor ultrashort transit interaction in femtochemistry.

Keywords: supercontinuum, ultrafast, SPIDER, ultra-broadband

Procedia PDF Downloads 224

Authors: Sh. Sohrabnezhad, A. Jafarzadeh

Abstract:

In this paper, MCM-41 mesoporous material nanofibers were synthesized by an electrospinning technique. The nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), and nitrogen adsorption–desorption measurement. Tetraethyl orthosilicate (TEOS) and polyvinyl alcohol (PVA) were used as a silica source and fiber forming source, respectively. TEM and SEM images showed synthesis of MCM-41 nanofibers with a diameter of 200 nm. The pore diameter and surface area of calcined MCM-41 nanofibers was 2.2 nm and 970 m²/g, respectively. The morphology of the MCM-41 nanofibers depended on spinning voltages.

Keywords: electrospinning, electron microscopy, fiber technology, porous materials, X-ray techniques

Procedia PDF Downloads 250

Authors: M. Kheirandish, S. Borhani

Abstract:

In this experiment Polystyrene/Zinc-oxide (PS/ZnO) nanocomposite fibers were produced by electrospinning technique using limonene as a green solvent. First, the morphology of electrospun pure polystyrene (PS) and PS/ZnO nanocomposite fibers investigated by SEM. Results showed the PS fiber diameter decreased by increasing concentration of Zinc Oxide nanoparticles (ZnO NPs). Thermo Gravimetric Analysis (TGA) results showed thermal stability of nanocomposites increased by increasing ZnO NPs in PS electrospun fibers. Considering Differential Scanning Calorimeter (DSC) thermograms for electrospun PS fibers indicated that introduction of ZnO NPs into fibers affects the glass transition temperature (Tg) by reducing it. Also, UV protection properties of nanocomposite fibers were increased by increasing ZnO concentration. Evaluating the effect of metal oxide NPs amount on mechanical properties of electrospun layer showed that tensile strength and elasticity modulus of the electrospun layer of PS increased by addition of ZnO NPs. X-ray diffraction (XRD) pattern of nanopcomposite fibers confirmed the presence of NPs in the samples.

Keywords: electrospininng, nanoparticle, polystyrene, ZnO

Procedia PDF Downloads 241

Authors: Ratchada Sopakayang, Gerhard A. Holzapfel

Abstract:

In this study, a new constitutive model is developed to describe the hyperelastic behavior of collagenous tissues with a parallel arrangement of collagen fibers such as ligaments and tendons. The model is formulated using a continuum approach incorporating the structural changes of the main tissue components: collagen fibers, proteoglycan-rich matrix and fiber-matrix interaction. The mechanical contribution of the interaction between the fibers and the matrix is simply expressed by a coupling term. The structural change of the collagen fibers is incorporated in the constitutive model to describe the activation of the fibers under tissue straining. Finally, the constitutive model can easily describe the stress-stretch nonlinearity which occurs when a ligament/tendon is axially stretched. This study shows that the interaction between the fibers and the matrix contributes to the mechanical tissue response. Therefore, the model may lead to a better understanding of the physiological mechanisms of ligaments and tendons under axial loading.

Keywords: constitutive model, fiber-matrix, hyperelasticity, interaction, ligament, tendon

Procedia PDF Downloads 301

Authors: A. Attaf A., I. Bouhaf Kharkhachi

Abstract:

Spray ultrasonic deposition technique of tin disulfide (SnS2) thin films know wide application due to their adequate physicochemical properties for microelectronic applications and especially for solar cells. SnS2 film was deposited by spray ultrasonic technique, on pretreated glass substrates at well-determined conditions.The effect of SnS2 concentration on different optical properties of SnS2 Thin films, such us MEB, XRD, and UV spectroscopy visible spectrum was investigated. MEB characterization technique shows that the morphology of this films is uniform, compact and granular. x-ray diffraction study detects the best growth crystallinity in hexagonal structure with preferential plan (001). The results of UV spectroscopy visible spectrum show that films deposited at 0.1 mol/l is large transmittance greater than 25% in the visible region.The band gap energy is 2.54 Ev for molarity 0.1 mol/l.

Keywords: MEB, thin disulfide, thin films, ultrasonic spray, X-Ray diffraction, UV spectroscopy visible

Procedia PDF Downloads 606

Authors: Jessica Chorostecki, Aashka Shah, Fen Bao, Ginny Bao, Edwin George, Navid Seraji-Bozorgzad, Veronica Gorden, Christina Caon, Elliot Frohman

Abstract:

Background: Parkinson’s Disease (PD) is a neuro degenerative disorder associated with the loss of dopaminergic cells and the presence α-synuclein (AS) aggregation in of Lewy bodies. Both dopaminergic cells and AS are found in the retina. Optical coherence tomography (OCT) allows high-resolution in-vivo examination of retinal structure injury in neuro degenerative disorders including PD. Methods: We performed a cross-section OCT study in patients with definite PD and healthy controls (HC) using Spectral Domain SD-OCT platform to measure the peripapillary retinal nerve fiber layer (pRNFL) thickness and total macular volume (TMV). We performed intra-retinal segmentation with fully automated segmentation software to measure the volume of the RNFL, ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), and the outer nuclear layer (ONL). Segmentation was performed blinded to the clinical status of the study participants. Results: 101 eyes from 52 PD patients (mean age 65.8 years) and 46 eyes from 24 HC subjects (mean age 64.1 years) were included in the study. The mean pRNFL thickness was not significantly different (96.95 μm vs 94.42 μm, p=0.07) but the TMV was significantly lower in PD compared to HC (8.33 mm3 vs 8.58 mm3 p=0.0002). Intra-retinal segmentation showed no significant difference in the RNFL volume between the PD and HC groups (0.95 mm3 vs 0.92 mm3 p=0.454). However, GCL, IPL, INL, and ONL volumes were significantly reduced in PD compared to HC. In contrast, the volume of OPL was significantly increased in PD compared to HC. Conclusions: Our finding of the enlarged OPL corresponds with mRNA expression studies showing localization of AS in the OPL across vertebrate species and autopsy studies demonstrating AS aggregation in the deeper layers of retina in PD. We propose that the enlargement of the OPL may represent a potential biomarker of AS aggregation in PD. Longitudinal studies in larger cohorts are warranted to confirm our observations that may have significant implications in disease monitoring and therapeutic development.

Keywords: Optical Coherence Tomography, biomarker, Parkinson's disease, alpha-synuclein, retina

Procedia PDF Downloads 438

Authors: H. Scholz, P. Kuehne, G. Heckenberger

Abstract:

Problems during the calving period (December until May) often are results in a high body condition score (BCS) at this time. At the end of the grazing period (frequently after early weaning), however, an increase of BCS can often be observed under German conditions. In the last eight weeks before calving, the body condition should be reduced or at least not increased. Rations with a higher amount of crude fiber can be used (rations with straw or late mowed grass silage). Fermentative digestion of fiber is slow and incomplete; that’s why the fermentative process in the rumen can be reduced over a long feeding time. Viewed in this context, feed intake of suckler cows (8 weeks before calving) in different rations and fermentation in the rumen should be checked by taking rumen fluid. Eight suckler cows (Charolais) were feeding a Total Mixed Ration (TMR) in the last eight weeks before calving and grass silage after calving. By the addition of straw (30 % [TMR1] vs. 60 % [TMR2] of dry matter) was varied the amount of crude fiber in the TMR (grass silage, straw, mineral) before calving. After calving of the cow's grass, silage [GS] was fed ad libitum, and the last measurement of rumen fluid took place on the pasture [PS]. Rumen fluid, plasma, body weight, and backfat thickness were collected. Rumen fluid pH was assessed using an electronic pH meter. Volatile fatty acids (VFA), sedimentation, methylene-blue, and amount of infusorians were measured. From these 4 parameters, an “index of rumen fermentation” [IRF] in the rumen was formed. Fixed effects of treatment (TMR1, TMR2, GS, and PS) and a number of lactations (3-7 lactations) were analyzed by ANOVA using SPSS Version 25.0 (significant by p ≤ 5 %). Rumen fluid pH was significantly influenced by variants (TMR 1 by 6.6; TMR 2 by 6.9; GS by 6.6 and PS by 6.9) but was not affected by other effects. The IRF showed disturbed fermentation in the rumen by feeding the TMR 1+2 with a high amount of crude fiber (Score: > 10.0 points) and a very good environment for fermentation during grazing the pasture (Score: 6.9 points). Furthermore, significant differences were found for VFA, methylene blue, and the number of infusorians. The use of rations with a high amount of crude fiber from weaning to calving may cause deviations from undisturbed fermentation in the rumen and adversely affect the utilization of the feed in the rumen.

Keywords: rumen fermentation, suckler cow, digestibility organic matter, crude fiber

Procedia PDF Downloads 144

Authors: Sawsan Domi

Abstract:

Khartoum is considering as one of the hottest cities all over the world, the mean monthly outdoor temperature remains above 30 ºC. Solar Radiation on Building Surfaces considered within the world highest values. Buildings in Khartoum is receiving huge amounts of watts/m2. Northern, eastern and western facades always receive a greater amount than the south ones. Therefore, these facades of the building must be better protected than the others. One of the most important design limits affecting indoor thermal comfort and energy conservation are building envelope design, self-efficiency in building materials and optical and thermo-physical properties of the building envelope. A small sun-facing glazing area is very important to provide thermal comfort in hot dry climates because of the intensive sunshine. This study aims to propose a work plan to help minimize the negative environmental effect of the climate on buildings taking the intensive use of glazing. In the last 15 years, there was a rapid growth in building sector in Khartoum followed by many of wrong strategies getting away of being environmental friendly. The intensive use of glazing on facades increased to commercial, industrial and design aspects, while the glass envelope led to quick increase in temperature by the reflection affects the sun on faces, cars and bodies. Logically, being transparent by using glass give a sense of open spaces, allowing natural lighting and sometimes natural ventilation keeping dust and insects away. In the other hand, it costs more and give more overheated. And this is unsuitable for a hot dry climate city like Khartoum. Many huge projects permitted every year from the Ministry of Planning in Khartoum state, with a design based on the intensive use of glazing on facades. There are no Laws or Regulations to control using materials in construction, the last building code -building code 2008- Khartoum state- only focused in using sustainable materials with no consider to any environmental aspects. Results of the study will help increase the awareness for architects, engineers and public about this environmentally problem. Objectives vary between Improve energy performance in buildings and Provide high levels of thermal comfort in the inner environment. As a future project, what are the changes that can happen in building permits codes and regulations. There could be recommendations for the governmental sector such as Obliging the responsible authorities to version environmental friendly laws in building construction fields and Support Renewable energy sector in buildings.

Keywords: building envelope, building regulations, glazed facades, solar radiation

Procedia PDF Downloads 220

Authors: Yonas Lamore, Abebe Beyene, Samuel Fekadu, Moa Megersa

Abstract:

Unaffordable construction cost of conventional water treatment plant and distribution system in most developing countries makes difficult to provide safe and adequate water for all households, especially for the rural setup. Water treatment at the source can be the best alternative. Solar disinfection is one alternative among point of use treatments. In this study, aqua lens, photovoltaic box and glass bottle were used subsequent to plant coagulants to evaluate microbial reduction potentials. Laboratory- and field-based experiments were conducted from May to August 2016. The Escherichia coli, total coliforms and heterotrophic plate counts were used as indicator organisms. The result indicated that aqua lens (AL), photovoltaic box (PV) and glass bottle (GB) have high inactivation rate subsequently almost for all indicator organisms in short solar exposure time. Total coliforms were inactivated in AL (SD = 15.8 °C, R2 = 0.92) followed by PV inactivation temperature associa- tion (SD = 11.6 C, R2 = 0.90), and the GB concentrator was inactivated (SD = 10.9 °C, R2 = 0.70) at turbidity level of 3.41 NTU. As the study indicated, aqua lens coupled with Moringa oleifera coagulant can be an effective with minimum cost for household water treatment system. The study also concludes heterotrophic bacteria were more resistant than other types of bacteria in SODIS with similar exposure time.

Keywords: acrylic glass, aqua lens, moringa olifera, photovoltaic box, solar disinfection, water treatment

Procedia PDF Downloads 24

Authors: Manasa Perikala, Asha Bhardwaj

Abstract:

Fluorescent carbon dots (CDs), a young member of Carbon nanomaterial family, has gained a lot of research attention across the globe due to its highly luminescent emission properties, non-toxic behavior, stable emission properties, and zero re-absorption lose. These dots have the potential to replace the use of traditional semiconductor quantum dots in light-emitting devices (LED’s, fiber lasers) and other photonic devices (temperature sensor, UV detector). However, One major drawback of Carbon dots is that, till date, the actual mechanism of photoluminescence (PL) in carbon dots is still an open topic of discussion among various researchers across the globe. PL mechanism of CDs based on wide particle size distribution, the effect of surface groups, hybridization in carbon, and charge transfer mechanisms have been proposed. Although these mechanisms explain PL of CDs to an extent, no universally accepted mechanism to explain complete PL behavior of these dots is put forth. In our work, we report parameters affecting the size and surface of CDs, such as time of the reaction, synthesis temperature and concentration of precursors and their effects on the optical properties of the carbon dots. The effect of auxochromes on the emission properties and re-modification of carbon surface using an external surface functionalizing agent is discussed in detail. All the explanations have been supported by UV-Visible absorption, emission spectroscopies, Fourier transform infrared spectroscopy and Transmission electron microscopy and X-Ray diffraction techniques. Once the origin of PL in CDs is understood, parameters affecting PL centers can be modified to tailor the optical properties of these dots, which can enhance their applications in the fabrication of LED’s and other photonic devices out of these carbon dots.

Keywords: carbon dots, photoluminescence, size effects on emission in CDs, surface modification of carbon dots

Procedia PDF Downloads 136

Authors: F. Stake

Abstract:

This work is a parametric study combining simple and well known optical theories. These simple theories are arranged to form part of one answer to the question: “Can a semi-transparent Thermo-Photo-Voltaic (TPV) emitter have an optical extinction spectrum so much greater than its optical absorption spectrum that it becomes its own band-pass pre-filter, and if so, how well might it be expected to suppress light of undesired wavelengths?” In the report, hypothetical materials and operating temperatures will be used for comparative analyses only. Thermal emission properties of these hypothetical materials were created using two openly available FORTRAN programs. Results indicate that if using highly transparent materials it may be possible to create a thermal emitter that is its own band-pass pre-filter.

Keywords: Christensen effect, DISORT, index of refraction, scattering

Procedia PDF Downloads 119

Authors: Keundong Lee, Dongha Yoo, Youngbin Tchoe, Gyu-Chul Yi

Abstract:

Light emitting diode (LED) array is an ideal optical stimulation tool for optogenetics, which controls inhibition and excitation of specific neurons with light-sensitive ion channels or pumps. Although a fiber-optic cable with an external light source, either a laser or LED mechanically connected to the end of the fiber-optic cable has widely been used for illumination on neural tissue, a new approach to use micro LEDs (µLEDs) has recently been demonstrated. The LEDs can be placed directly either on the cortical surface or within the deep brain using a penetrating depth probe. Accordingly, this method would not need a permanent opening in the skull if the LEDs are integrated with miniature electrical power source and wireless communication. In addition, multiple color generation from single µLED cell would enable to excite and/or inhibit neurons in localized regions. Here, we demonstrate flexible and color tunable µLEDs for the optogenetic device applications. The flexible and color tunable LEDs was fabricated using multifaceted gallium nitride (GaN) nanorod arrays with GaN nanorods grown on InxGa1−xN/GaN single quantum well structures (SQW) anisotropically formed on the nanorod tips and sidewalls. For various electroluminescence (EL) colors, current injection paths were controlled through a continuous p-GaN layer depending on the applied bias voltage. The electric current was injected through different thickness and composition, thus changing the color of light from red to blue that the LED emits. We believe that the flexible and color tunable µLEDs enable us to control activities of the neuron by emitting various colors from the single µLED cell.

Keywords: light emitting diode, optogenetics, graphene, flexible optoelectronics

Procedia PDF Downloads 211

Authors: Giuseppe Spampinato, Salvatore Curti, Ivana Guarneri, Arcangelo Bruna

Abstract:

This document describes an advanced system and methodology for Cross Traffic Alert (CTA), able to detect vehicles that move into the vehicle driving path from the left or right side. The camera is supposed to be not only on a vehicle still, e.g. at a traffic light or at an intersection, but also moving slowly, e.g. in a car park. In all of the aforementioned conditions, a driver’s short loss of concentration or distraction can easily lead to a serious accident. A valid support to avoid these kinds of car crashes is represented by the proposed system. It is an extension of our previous work, related to a clustering system, which only works on fixed cameras. Just a vanish point calculation and simple optical flow filtering, to eliminate motion vectors due to the car relative movement, is performed to let the system achieve high performances with different scenarios, cameras and resolutions. The proposed system just uses as input the optical flow, which is hardware implemented in the proposed platform and since the elaboration of the whole system is really speed and power consumption, it is inserted directly in the camera framework, allowing to execute all the processing in real-time.

Keywords: clustering, cross traffic alert, optical flow, real time, vanishing point

Procedia PDF Downloads 203

Authors: Hamad Al-Turaif, Usman Saeed

Abstract:

The development of nanofibers with the help of electrospinning is being prioritized as a method of choice because of the simplicity and efficiency of the process. The parameters of the electrospinning process effectively convert the polymer solution into an electrospun final product made of the desired diameter of nanofiber. The aim of the study presented is to recognize and analyze the effect of proposed parameters on biodegradable and biocompatible polylactic acid (PLA)/polybutylene succinate (PBS) nanofiber developed by the electrospinning process. The morphology of the fiber is characterized by implementing Scanning Electron Microscope. Studies were conducted to characterize the result of using different electrospinning parameters on the final diameter and orientation of fiber. It was determined that varying polymer solution concentration, feed rate, and applied voltage show different outcomes. The best results were obtained at 6% polymer solution concentration, 20 kV, and 0.5 ml/h, which can be applicable for biomedical applications. Finally, protein adsorption and mechanical testing were conducted on the PLA/PBS fiber.

Keywords: electrospinning, polylactic acid, polybutylene succinate, morphology

Procedia PDF Downloads 133

Authors: Talebi Aliasghar, Ebrahimpour Komeleh Hooman, Maghsoudi Ali Akbar

Abstract:

In reinforced concrete (RC) structures, beam-column connection region has a considerable effect on the behavior of structures. Using fiber reinforcement polymer (FRP) for the strengthening of connections in RC structures can be one of the solutions to retrofitting this zone which result in the enhanced behavior of structure. In this paper, these changes in behavior by using FRP for high strength concrete beam-column connection have been studied by finite element modeling. The concrete damage plasticity (CDP) model has been used to analyze the RC. The results illustrated a considerable development in load-bearing capacity but also a noticeable reduction in ductility. The study also assesses these qualities for several modes of strengthening and suggests the most effective mode of strengthening. Using FRP in flexural zone and FRP with 45-degree oriented fibers in shear zone of joint showed the most significant change in behavior.

Keywords: HSC, beam-column connection, Fiber Reinforcement Polymer, FRP, Finite Element Modeling, FEM

Procedia PDF Downloads 159

Authors: Z. Abdollahnejad, M. Mastali, F. Pacheco-Torgal

Abstract:

Waste reuse is crucial in a context of circular economy and zero waste sustainable needs. Some wastes deserve further studies by the scientific community not only because they are generated in high amount but also because they have a low reuse rate. This paper reports results of 32 hybrid cement mortars based on fly ash and waste glass. They allow to explore the influence of mix design on the cost and on the embodied carbon of the hybrid cement mortars. The embodied carbon data for all constituents were taken from the database Ecoinvent. This study led to the development of a mixture with just 70 kg CO2e.

Keywords: waste reuse, fly ash, waste glass, hybrid cements, cost, embodied carbon

Procedia PDF Downloads 331

Authors: Olga V. Kharchenko

Abstract:

Applicability of a KTA crystal-based laser system with optical parametric oscillators (OPO) generation to lidar sounding of the atmosphere in the spectral range 3–4 µm is studied in this work. A technique based on differential absorption lidar (DIAL) method and differential optical absorption spectroscopy (DOAS) is developed for lidar sounding of trace atmospheric gases (TAG). The DIAL-DOAS technique is tested to estimate its efficiency for lidar sounding of atmospheric trace gases.

Keywords: atmosphere, lidar sounding, DIAL, DOAS, trace gases, nonlinear crystal

Procedia PDF Downloads 403

Authors: Lan Nguyen, Lam Cao Van

Abstract:

Thuan Phuoc is a suspension bridge built in Danang city, Vietnam. Because this bridge locates near the estuary, its structure has degraded rapidly. Many cracks have currently occurred on most of the concrete piers of the curved approach spans. This paper aims to present the results of diagnostic analysis of causes for cracks as well as some calculations for strengthening piers by carbon fiber reinforced polymer (CFRP). Besides, it describes how to use concrete nonlinear analysis software ATENA to diagnostically analyze cracks, strengthening designs. Basing on the results of studying the map of distributing crack on Thuan Phuoc bridge’s concrete piers is analyzed by the software ATENA is suitable for the real conditions and CFRP would be the best solution to strengthen piers in a sound and fast way.

Keywords: ATENA, bridge pier strengthening, carbon fiber reinforced polymer (CFRP), crack prediction analysis

Procedia PDF Downloads 242

Authors: Pasquale Porcu, Mireille Vonlanthen, Gerardo Zaragoza-Galán, Ernesto Rivera

Abstract:

In this work, we report the synthesis of a novel series of dendritic molecules bearing donor-acceptor groups (pyrene-bodipy) with potential applications in energy transfer. Initially, first and second generation Fréchet type dendrons (Py2-G1OH and Py4-G2OH) were prepared from 1-pyrenylbutanol and 3,5-dihydroxybenzylic alcohol. These compounds were further linked to a bodipy unit via an esterification reaction in order to obtain the desired products (Bodipy-G1Py2) and Bodipy-G2Py4). These compounds were fully characterized by FTIR and 1H and 13C NMR spectroscopy and their molecular weights were determined by MALDITOF. The optical and photophysical properties of these molecules were evaluated by absorbance and fluorescence spectroscopy, in order to compare their behaviour with other analogue molecules.

Keywords: bodipy, dendritic molecules, optical properties, pyrene

Procedia PDF Downloads 284

Authors: Karkour Selma

Abstract:

We conducted first principles full potential calculations using the Wien2k code to explore the structural, electronic, magnetic, and optical properties of SiNi₂O₄, a cubic normal spinel oxide. Our calculations, based on the GGA-PBEsol of the generalized gradient approximation, revealed several key findings. The spinel oxides exhibited a stable cubic structure in the ferromagnetic phase and showed 100% spin polarization. We determined the equilibrium lattice constant and internal parameter values. In terms of the electronic properties, we observed a direct bandgap of 2.68 eV for the spin-up configuration, while the spin-down configuration exhibited an indirect bandgap of 0.82 eV. Additionally, we calculated the total density of states and partial densities for each atom, finding a magnetic moment spin density of states of 8.0 μB per formula unit. The optical properties have been calculated. The real, Ԑ₁(ω) and the imaginary, Ԑ₂(ω) parts of the complex dielectric constants, refractivity, reflection and energy loss when light scattered from the material. The absorption region spanned from 1.5 eV to 14 eV, with significant intensity. The calculated results confirm the suitability of this material for optical and spintronic devices application.

Keywords: DFT, spintronic, GGA, spinel

Procedia PDF Downloads 76

Authors: Shaher Bano, Samia Fida, Asif Israr

Abstract:

The synergistic effect of properties of metals and fibers reinforced laminates has diverted attention of the world towards use of robust composite materials known as fiber-metal laminates in many high performance applications. In this study, modification of an adhesively bonded joint as a single lap joint of carbon fibers based CARALL FML has done to increase interlaminar shear strength of the joint. The effect of different configurations of joint designs such as spews, stepped and modification in adhesive by addition of nano-fillers was studied. Both experimental and simulation results showed that modified joint design have superior properties as maximum force experienced stepped joint was 1.5 times more than the simple lap joint. Addition of carbon nano-tubes as nano-fillers in the adhesive joint increased the maximum force due to crack deflection mechanism.

Keywords: adhesive joint, Carbon Reinforced Aluminium Laminate (CARALL), fiber metal laminates, spews

Procedia PDF Downloads 237

Authors: Tigist Girma Kedane

Abstract:

The purpose of this paper is to evaluate the properties of Ethiopian bamboo fiber polymer composites for headliner materials in the automobile industry. Accurate evaluation of its mechanical properties is thus critical for predicting its behavior during a vehicle's interior impact assessment. Conventional headliner materials are higher in weight, nonbiodegradable, expensive in cost, and unecofriendly during processing compared to the current researched materials. Three representatives of bamboo plants are harvested in three regions of bamboo species, three groups of ages, and two harvesting months. The statistical analysis was performed to validate the significant difference between the mean strength of bamboo ages, harvesting seasons, and bamboo species. Two-year-old bamboo fibers have the highest mechanical properties in all ages and November has higher mechanical properties compared to February. Injibara and Kombolcha have the highest and the lowest mechanical properties of bamboo fibers, respectively. Bamboo fiber epoxy composites have higher mechanical properties compared to bamboo fiber polypropylene composites. The flexural strength of bamboo fibre polymer composites has higher properties compared to tensile strength. Ethiopian bamboo fibers and their polymer composites have the best mechanical properties for the composite industry, which is used for headliner materials in the automobile industry compared to conventional headliner materials.

Keywords: bampoo species, culm age, harvesting seasons, mechanical properties, polymer composite

Procedia PDF Downloads 63

Authors: Mohamed Ouazene

Abstract:

The insulating properties of the polymers are widely used in electrical engineering for the production of insulators and various supports, as well as for the insulation of electric cables for medium and high voltage, etc. These polymeric materials have significant advantages both technically and economically. However, although the insulation with polymeric materials has advantages, there are also certain disadvantages such as the influence of the heat which can have a detrimental effect on these materials. Polyvinyl chloride (PVC) is one of the polymers used in a plasticized state in the cable insulation to medium and high voltage. The studied material is polyvinyl chloride (PVC 4000 M) from the Algerian national oil company whose formula is: Industrial PVC 4000 M is in the form of white powder. The test sample is a pastille of 1 mm thick and 1 cm in diameter. The consequences of increasing the temperature of a polymer are modifications; some of them are reversible and others irreversible [1]. The reversible changes do not affect the chemical composition of the polymer, or its structure. They are characterized by transitions and relaxations. The glass transition temperature is an important feature of a polymer. Physical aging of PVC is to maintain the material for a longer or shorter time to its glass transition temperature. The aim of this paper is to study this phenomenon by the method of thermally stimulated depolarization currents. Relaxations within the polymer have been recorded in the form of current peaks. We have found that the intensity decreases for more residence time in the polymer along its glass transition temperature. Furthermore, it is inferred from this work that the phenomenon of physical aging can have important consequences on the properties of the polymer. It leads to a more compact rearrangement of the material and a reconstruction or reinforcement of structural connections.

Keywords: depolarization currents, glass transition temperature, physical aging, polyvinyl chloride (PVC)

Procedia PDF Downloads 389

Authors: S. Palaniyappan, P. K. Chennam, M. Trautmann, H. Ahmad, T. Mehner, T. Lampke, G. Wagner

Abstract:

In structural-health monitoring of fiber reinforced plastics (FRPs), every single inorganic fiber sensor that are integrated into the bulk material requires an electrical insulation around itself, when the surrounding reinforcing fibers are electrically conductive. This results in a more accurate data acquisition only from the sensor fiber without any electrical interventions. For this purpose, thin nano-films of aluminium oxide (Al₂O₃)-based electrical-insulation coatings have been fabricated around the Silicon Carbide (SiC) single fiber sensors through reactive DC magnetron sputtering technique. The sputtered coatings were amorphous in nature and the thickness of the coatings increased with an increase in the sputter time. Microstructural characterization of the coated fibers performed using scanning electron microscopy (SEM) confirmed a homogeneous circumferential coating with no detectable defects or cracks on the surface. X-ray diffraction (XRD) analyses of the as-sputtered and 2 hours annealed coatings (825 & 1125 ˚C) revealed the amorphous and crystalline phases of Al₂O₃ respectively. Raman spectroscopic analyses produced no characteristic bands of Al₂O₃, as the thickness of the films was in the nanometer (nm) range, which is too small to overcome the actual penetration depth of the laser used. In addition, the influence of the insulation coatings on the mechanical properties of the SiC sensor fibers has been analyzed.

Keywords: Al₂O₃ thin film, electrical insulation coating, PVD process, SiC fibre, single fibre tensile test

Procedia PDF Downloads 124

Authors: Mardiati Zain, W. S. N. Rusmana, Erpomen, Malik Makmur, Ezi Masdia Putri

Abstract:

Background and Aim: The leaves of the Leucaenaleucocephala tree have potential as a nitrogen source for ruminants. Leucaena leaf meal as protein supplement has been shown to improve the feed quality of ruminants. The effects of different levels of Leucaena leucocephala supplementation as substitute of concentrate on fiber digestibility and in vitro rumen fermentation characteristics were investigated. This research was conducted in vitro. The study used a randomized block design consisting of 3 treatments and 5 replications. The treatments were A. 40% rice straw ammoniated + 60% concentrate, B. 40% rice straw ammoniated + 50% concentrate + 10% Leucaena leuchephala, C. 40% rice straw ammoniated + 40% concentrate + 20% Leucaena leuchephala, Result: The results showed that the addition of Leucaena leucocephala increased the digestibility of Neutral detergent Fiber NDF and Acid Detergent Fiber (ADF) (p < 0.05). In this study, rumen NH3, propionate, amount of escape protein and total Volatyl Fatty Acid (VFA) were found increased significantly at treatment B. No significant difference was observed in acetate and butyrate production. The populations of total protozoa and methane production had significantly decreased (P < .05) in supplemented group. Conclusion: Supplementation of leuchaena leucochepala on completed feed based on ammoniated rice straw in vitro can increase fiber digestibility, VFA production and decreased protozoa pupulataion and methane production. Supplementation of 10% and 20% L. leucochepala were suitable to be used for further studies, therefore in vivo experiment is required to study the effects on animal production.

Keywords: digestibility, Leucaena leucocephala, complete feed, rice straw ammoniated

Procedia PDF Downloads 156

Authors: K. Khadidja

Abstract:

Solitons are stable solution of nonlinear Schrodinger equation. Their stability is due to the exact combination between nonlinearity and dispersion which causes pulse broadening. Higher order solitons are born when nonlinear length is N multiple of dispersive length. Soliton order is determined by the number N itself. In this paper, evolution of higher order solitons is illustrated by simulation using Matlab. Results show that higher order solitons change their shape periodically, the reason why they are bad for transmission comparing to fundamental solitons which are constant. Partial analysis of a soliton of higher order explains that the periodic shape is due to the interplay between nonlinearity and dispersion which are not equal during a period. This class of solitons has many applications such as generation of supercontinuum and the impulse compression on the Femtosecond scale. As a conclusion, the periodicity which is harmful to transmission can be beneficial in other applications.

Keywords: dispersion, nonlinearity, optical fiber, soliton

Procedia PDF Downloads 168

Authors: Himanshu Pavagadhi, Maunik Jani, S. M. Vyas, Jaymin Ray, Vimal Patel, Piyush Patel, Jignesh P. Raval

Abstract:

The preparation of pure and Sn-doped cadmium sulfide (CdS) pellets was carried out using a compression technique with a pelletizer. The energy dispersive X-ray (EDX) analysis is used to confirm the purity and stoichiometric ratio of Cd, S, and Sn in the prepared pellets. The surface morphology of the pellets was examined using a scanning electron microscope. Both XRD and Raman scattering spectrum analysis confirmed the doping effect in the CdS pellets. The X-ray diffraction (XRD) analysis confirmed the hexagonal structure and revealed that the grain size decreases with increasing Sn dopant concentration in the parent CdS pellet. The optical properties of the pellets were evaluated by measuring diffuse reflectance using a UV-vis spectrophotometer. The analysis indicated that as the Sn concentration increases in the parent CdS pellet, the optical band gap decreases. This implies that the optical properties of the CdS material are also affected by the Sn dopant.

Keywords: CdS, Sn dopant, UV-Spetrophotometer, XRD

Procedia PDF Downloads 33

Authors: Syed A. Bukhari, Ankur Goswmai, Dale Hume, Thomas Thundat

Abstract:

Here we demonstrate mechanical detection of photo-induced Insulator to metal transition (MIT) in ultra-thin vanadium dioxide (VO₂) micro strings by using < 100 µW of optical power. Highly focused laser beam heated the string locally resulting in through plane and along axial heat diffusion. Localized temperature increase can cause temperature rise > 60 ºC. The heated region of VO₂ can transform from insulating (monoclinic) to conducting (rutile) phase leading to lattice compressions and stiffness increase in the resonator. The mechanical frequency of the resonator can be tuned by changing optical power and wavelength. The first mode resonance frequency was tuned in three different ways. A decrease in frequency below a critical optical power, a large increase between 50-120 µW followed by a large decrease in frequency for optical powers greater than 120 µW. The dynamic mechanical response was studied as a function of incident optical power and gas pressure. The resonance frequency and amplitude of vibration were found to be decreased with increasing laser power from 25-38 µW and increased by1-2 % when the laser power was further increased to 52 µW. The transition in films was induced and detected by a single pump and probe source and by employing external optical sources of different wavelengths. This trend in dynamic parameters of the strings can be co-related with reversible Insulator to metal transition in VO₂ films which creates change in density of the material and hence the overall stiffness of the strings leading to changes in string dynamics. The increase in frequency at a particular optical power manifests a transition to a more ordered metallic phase which tensile stress onto the string. The decrease in frequency at higher optical powers can be correlated with poor phonon thermal conductivity of VO₂ in conducting phase. Poor thermal conductivity of VO₂ can force in-plane penetration of heat causing the underneath SiN supporting VO₂ which can result as a decrease in resonance frequency. This noninvasive, non-contact laser-based excitation and detection of Insulator to metal transition using micro strings resonators at room temperature and with laser power in few µWs is important for low power electronics, and optical switching applications.

Keywords: thermal conductivity, vanadium dioxide, MEMS, frequency tuning

Procedia PDF Downloads 120