1,081 research outputs found

    A normalized difference vegetation index (NDVI) time-series of idle agriculture lands: A preliminary study

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    In this paper, the NDVI time-series collected from the study area between year 2003 and 2005 of all land cover types are plotted and compared. The study area is the agricultural zones in Banphai District, Khonkean, Thailand. The LANDSAT satellite images of different dates were first transformed into a time series of Normalized Difference Vegetation Index (NDVI) images before the investigation. It can be visually observed that the NDVI time series of the Idle Agriculture Land (IAL) has the NDVI values closed to zero. In other words, the trend of the NDVI values remains, approximately, unchanged about the zero level for the whole period of the study time. In contrast, the non-idle areas hold a higher level of the NDVI variation. The NDVI values above 0.5 can be found in these non-idle areas during the growing seasons. Thus, it can be hypothesized that the NDVI time-series of the different land cover types can be used for IAL classification. This outcome is a prerequisite to the follow-up study of the NDVI pattern classification that will be done in the near future

    Using Czech TCT to Assess Safety Impact of Deceleration Lane at Thai U-turns

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    Purpose of this study is to evaluate safety impact of the deceleration lane at the Upstream Zone of at-grade U-turns on 4-lane divided Thai highways. A substantial speed reduction is required by vehicles for diverging and making U-turn, and the deceleration lanes are provided for this purpose. These lanes are also providing a storage space for the U-turning vehicles to avoid unnecessary blockage of through lanes and reduce the potential of rear-end collisions. The safety at the U-turn is greatly influenced by the proper or improper use of the deceleration lanes. Subject to their length, full or partial speed adjustment can occur within the deceleration lane also the road users’ behavior is influenced. To assess the safety impact, the four groups of U-turns with the varying length of deceleration lanes were identified. Owing to limitation of availability and reliability of road crash data in Thailand, widely accepted Traffic Conflict Technique (TCT) was used as an alternative and proactive methodology. The U-turns’ geometric data, traffic conflicts and volume data were recorded in the field at 8 locations, 8 hours per location. Severity Conflict Rate (SCR) was assessed by applying a weighing factor (based on the severity grades according to the Czech TCT) to the observed conflicts related to the conflicting traffic volumes. A comparative higher value of SCR represents a lower level of safety. According to the results, increase in the functional length of the deceleration lane yields a lower value of SCR and a higher level of the road safety

    Fatigue behavior of kenaf fibre reinforced epoxy composites

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    Towards green material, fatigue life of epoxy and its unidirectional kenaf fibre reinforced epoxy composites were investigated. These specimens were hand lay-out made. The specimens were cycled to tension-tension fatigue loading at stress ratio of 0.5 and 5 Hz of frequency to determine the fatigue life and its life characteristic at given 5 stress levels. Fibre content ratios were found to affect fatigue life strongly on the low cycle fatigue regime as illustrated with stress level versus cycles to failure. It is found that kenaf fibre reinforced epoxy composites with higher fibre content posses higher load carrying capacity and degradation rates. The existing models developed by Mandell, Manson-Coffin and Hai-Tang were adopted to predict the fatigue life. Some of the models show minor similarities with the experimental data, but not universally applicable to predict the fatigue life when it comes with various amount of fibre volume

    Flexural Response of CFRP-Strengthened Steel Beams with Initial Bond Defects

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    This paper presents the flexural behavior of steel beams strengthened with partial-length adhesive-bonded carbon fiber-reinforced polymer (CFRP) plates under static four-point bending. An initial bond defect was intentionally introduced in the constant moment region of the CFRP-strengthened steel beams. In the experimental program, the test variables included the size of the initial bond defect, FRP modulus, FRP plate length, and condition of the steel beam before installation of the FRP plate (undamaged and pre-yielded conditions). Based on the test results, the presence of the initial bond defect changed the failure mode of FRP-strengthened steel beam from the fiber rupture to intermediate plate debonding. With the initial bond defect, the effectiveness of the FRP strengthening scheme decreased as FRP modulus increased. The stiffness, strength, and ductility index of the CFRP-strengthened beam with the initial bond defect decreased as the defect size increased. However, the initial bond defect had no detrimental effect on the maximum load capacity and ductility index of the strengthened beams. The strengthening effectiveness in terms of stiffness, strength, and ductility enhancement was more pronounced in the case of the pre-damaged steel beam, of which the bottom flange had already yielded before installation of the CFRP plate, than the undamaged steel beam

    Enhancement of light absorption using Nanoparticles Embedded Double layer Anti-Reflection Coating

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    The formation of nanoparticles embedded composite materials is a means for engineering the electrical and optical properties of thin films. This paper proposes the use of gold and silver nano-particles(NPs) to fine tune the effective index of two dielectric layers towards anti-reflection coating applications. Here, the upper layer is MgF2 (magnesium fluoride) and the lower layer is PMMA (Polymethylmethacrylate). The effect of embedding the nano-particles in the PMMA layer on the transmission spectrum is studied while tuning the concentration (volume fraction) and size of particles. With the increase in the size of the nano-particles there is a red shift in the transmission dip. On varying the nano-particle size the peak absorption can be shifted to the desired wavelength. Considering 50 nm silver nano-particle with the volume fraction ranging from 0.001 to 0.05, maximum transmission of light is observed under lower wavelength range of visible spectrum across the novel structur

    Chemical Modification of Cotton Fabric Using Chitosan and Hydrolyzed Silk Fibroin

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    A cotton fabric modified with chitosan (CS) and hydrolyzed fibroin (HF) was prepared by using glyoxal as crosslinker. Fixation of CS and HF on cotton fabric was confirmed by Scanning electron microscopy (SEM) and Fourier transform infrared spectrometer (FTIR) and color depth (K/S) of finished fabrics which was dyed with acid dye. %Water absorption, tensile strength as well as %elongation and crease recovery angle were evaluated. Results of SEM micrograph and FTIR spectra clearly confirmed fixation of CS and HF on cotton fabric surface by using glyoxal as crosslinker. %Water absorption and %elongation of the finished fabrics increased with increased concentration of HF in finishing solution. However, decreases in tensile strength and % crease recovery were observed when increased concentration of HF was used. This work demonstrated that the surface properties of cotton fabrics was changed by HF modification, fixation of CS and HF placed onto cotton fabric changed the fabric surface properties, which facilitated more uptake of chemicals such as water and anionic acid dye. The cotton fabrics finished with hydrolyzed fibroin exhibited antibacterial activity against the growth of S.aureus and E.coli which facilitated the finished cotton fabric as  a functional materials, for example in a medical application

    Design of Visible Light Communication Receiver for On-Off Keying Modulation by Adaptive Minimum-Voltage Cancelation

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    In this paper, a new design of visible light communication (VLC) receiver for on-off keying (OOK) modulation is proposed. The design is based on the cancelation of minimum offset voltage of the received OOK signal, using a novel minimum-voltage detection circuit. This circuit is capable of tracking the minimum voltage of an input signal even if its value increases with time. Experimental results show that the proposed receiver is immune to the interference from sunlight and indoor fluorescent lights

    Utilization of Agricultural By-Products for Alpha-Amylase Production under Solid State Fermentation by Bacillus Subtilis

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    The production of alpha-amylase by Bacillus subtilis was investigated under different cultivation conditions on two different solid substrates as the support, i.e. oil palm empty fruit bunch (OPEFB) and rice straw fibers using solid state fermentation (SSF) process. Both solid substrates were first pre-treated using NaOH to remove lignin and silica and to break down the hemicellulose structures. The influences of incubation time, incubation temperature and the additional carbon and nitrogen sources on the production of alpha-amylase by B. subtilis were investigated. After 48 h of incubation, the highest enzyme activities were obtained at 39.9 U/g and 23.5 U/g for rice straw and OPEFB fibers, respectively. The optimum temperature for alpha-amylase production was observed at 45°C for the OPEFB fibers and 55°C for the rice straw fibers. Among the defined carbohydrates, the addition of glucose (0.02 g/g dry substrate) has significantly improved the production of alpha-amylase. Similar effect was observed when yeast extract (0.01 g/g dry substrate) was supplemented as the additional nitrogen source. Rice straw fibers appeared to be the best solid substrate in producing alpha-amylase (276 U/g) in SSF under these optimum cultivation conditions

    Kinetic Study of Palm Fatty Acid Distillate Esterification with Glycerol over Strong Acidic Cation Exchanger Tulsion 42SM

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    Palm Fatty Acid Distillate (PFAD) is a byproduct of CPO production. PFAD conversion into monoglyceride would give significant economic added value to it. With free fatty acid as the major component which composes the PFAD, then the esterification process was the right choice. Utilization of strong acidic cation resin as a catalyst is interesting. The catalyst could be easily separated physically. Natural esterification reaction would run reversibly so that the reflux system would be created to remove water. Reflux system used xylene as the solvent. To find the optimum condition for reaction parameters, reaction temperature, mole ratio of PFAD-glycerol, and catalyst loading were varied. Two heterogeneous reaction mechanisms, Langmuir - Hinshelwood and Eley - Rideal model, were tried to fit with the experimental data which resulted in the first model fitted the experimental data better than the second model. The reaction mechanism would involve the side reaction of diglyceride and triglyceride formation

    Analysis of Advanced Process Control Technology and Economic Assessment Improvement

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    Advanced Process Control (APC) is considered for investment after the Distributed Control System (DCS) and Historian System of Industrial Automation and Control Systems (IACS) had been implemented. The benefits of APC application can be observed by economic assessment (EA), however the EA technique is still behind the development of APC technology. We review the literature on APC and EA and highlight the potential future development
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