Advanced Materials Research Vols. 488-489

Abstract: Proper heat management is necessary for better optical performance of high power light emitting diodes (LEDs). However, the thermal behavior of the LEDs differs as the chip technology changes. In this study, the InGaAlP and InGaN based amber and green LED were used to investigate the influence of different operating conditions on its thermal and optical performances. The increasing driving current affects the InGaN LED more than the InGaAlP LED. As the driving current increases, the green and amber LEDs loses its wall-plug efficiency (WPE) from 18.1 to 10% and 31.1 to 27.1% respectively. The higher drop in WPE of green LED was contributed by the higher junction temperature which rises more than 11.1°C than the amber LED. The RthJA was reduced around 4 K/W in green LED and only 1.9 K/W in the amber LED. However, the increasing ambient temperature give significant effect to the thermal behavior of the amber LED. As the ambient temperatures increases, the WPE of the amber LED reduces from 29.7 to 20.7% whereas the green LED loses its efficiency by 0.6%. By investigating the thermal and optical behaviors of the different chip LEDs under different operating conditions, the appropriate working condition of the LEDs at the optimum level can be identified.

Abstract: The frozen instant food packaging is the one of disposal product, which produced from petroleum–based plastic and has been accumulated worldwide pressuring on the environment. Therefore, the biodegradable plastics have become key candidates in this application. Poly(lactic acid) (PLA) was regarded as one of the most promising biodegradable polymer due to its good mechanical properties. The aim of this work was to study on the freezability and microwavability of PLA through crosslink reaction. For the improvement of the processibility of PLA, hyperbranched polymer (HBP) and polypropylene glycol (PPG) were used as plasticizer. Then the crosslinking of PLA was introduced by addition of peroxide (Luperox101) and triallyl isocyanurate (TAIC) in an internal mixer. Neat and modified PLA samples were characterized and testing for mechanical properties. From the gel content results, it was showed the increased value with the increased content of TAIC due to the denser crosslinked structure of polymer. This result was confirmed by FT-IR spectra. All modified PLA samples showed the higher %strain at break than neat PLA. In addition, impact resistance in frozen state showed the results of modified PLA with 0.1wt% of peroxide and 0.15 wt% of TAIC, was higher than neat PLA. Moreover, this composition also showed the highest microwave response and heat accumulation was suppressed when the specimen was immersed in the water during the test. From the results obtained in this work, the further investigation is needed to pursue and elucidate the relationship between the polymer structure and heat absorption when materials undergo the microwave radiation.

Abstract: Laser sensor such as laser range finder (LRF) become more and more famous nowadays, many researchers has used, developed and integrate the laser sensor inside their system to achieve their goals. In this paper, we use one of the flagship products of Hokuyo companies, especially their photo sensor/SOKUIKI sensor or known as 2D LRF sensor, a URG-04LX-UG01. Here we review the most recent application on a research work that uses URG-04LX-UG01 since this product launched in 2010. In point of view of interface, sensor combination, environment of use, and functionality of the sensor itself is how we deliver the review. The uniqueness of the application applied is how we assess the research work.

Abstract: This work presents the chitin preparation from waste sources, the chitin powders were successfully extracted from shrimp shell, crab shell and squid pen. To prepare chitin powders, all raw materials were washed and grounded using agate mortar, which the particle size of powder is 212–250 μm. Then, the powdered materials were immersed into solution of chloroform and methanol (with 2:1 ratio) at room temperature for removing fat. The deprotienation and decarbonation, the samples were immersed in 50 wt% of NaOH solution for 24 h and in 4 wt% of HCl for 1 h, respectively. The XRD, FT-IR and TGA techniques were used to indicate the different characteristic between α-chitin and β-chitin prepare.

Abstract: In this work we report the preparation of colloidal silver nanoparticles. In order to prepare the silver nanoparticles laser ablation method has been used.A silver coin as a target (purity 99.9 %) was ablated by a Q-Switched Nd:YAG laser with a fluence of about 91 mJ/cm2 at a repetition rate of 10 Hz at room temperature. In order to evaluate these particles transmission electron microscopy (TEM) and spectrophotometry (from UV to NIR) have been used. The average size of prepared nanoparticles is ~ 20 nm. The importance of morphology of nanoparticles has been investigated. Developed applications of silver nanoparticles have been studied,silver nanoparticles are considered as biocompatible and low in toxicity and have good potential for biological applications. Lately silver nanoparticles have found a novel approach in different fields of medicine, biology and industry.

Abstract: Direct metal laser sintering (DMLS) is one of the methods in layer manufacturing technologies by which metal powder can be directly used to produce both prototype and production tools. The components manufactured by DMLS should have essential hardness for its application in the industry. This study was carried out to determine the optimum process parameters influencing the hardness of the components produced by DMLS. Sintering speed, hatch spacing, post contouring, infiltration and hatch type are the process parameters taken up for study. Statistical design of experiments using Taguchi’s orthogonal array was employed for this study. The experimental data obtained were analyzed using ANOVA. From the results, it is found that one of the process parameters; scan spacing affects the hardness of the parts produced by this technology to a significant extent.

Abstract: This work presents the results of a study carried out to determine the sliding wear behavior and its effect on the process parameters of components manufactured by selective laser sintering (SLS). A standard procedure and specimen had been used in the present study to find the wear behavior. Using Taguchi’s experimental technique, an orthogonal array of L4 had been developed. Sliding wear testing using pin-on-disk machine was carried out and analysis of variance (ANOVA) technique was used to investigate the effect of process parameters and to identify the main process parameter that influences the properties of wear behavior on the SLS components. It has been found that scan spacing had more influence on wear as compared to other selected process parameters, slice thickness and infiltration.

Abstract: This work presents the results of a study carried out to determine the reciprocating wear behavior and its effect on the process parameters of components manufactured by selective laser sintering (SLS). A standard procedure and specimen had been used in the present study to find the wear behavior. Using Taguchi’s experimental technique, an orthogonal array of modified L9 had been developed. Reciprocating wear testing was carried out and analysis of variance (ANOVA) technique was used to investigate the effect of process parameters and to identify the main process parameter that influences the properties of wear behavior on the SLS components. It has been found that laser power had more influence on wear as compared to other selected process parameters. Micro-structural analysis was also carried out using scanning electron microscope on the wear testing sample.

Abstract: In the underground data gathering and processing system, TMS320VC55X acquires signal and send it to display correctly on the LCD. The related hardware and software design of system is introduced in this paper. System adopts MzLH01-12864 display module with serial peripheral interface to realize graphic & text display. On the basis of the hardware interface circuit, SPI working mode of DSP multi-channel buffer serial port, software protocol and sequential flow are recommended. System realizes to display signal on LCD correctly, to demonstrate multiple menu of character and graphics and to implement the human-computer interaction.

Abstract: In this paper, a variational formulation by integral equations for the study of acoustic radiation by thin axisymmetric bodies is developed. This new approach derives from the three-dimensional variational formulation. It is based on the Fourier decomposition with respect to the angle of revolution. The three-dimensional problem is reduced to the resolution of several two-dimensional problems. Thus, by construction, the obtained axisymmetric variational equation is prepared to the numerical calculations because it avoids the regularisation of the double normal derivative of modal Green’s function. As for the Fourier coefficients of the singular part of Green’s function and its normal derivative, they are evaluated precisely by the same recurrence relation expressed in terms of the complete elliptic integrals. In addition, the axisymmetric free term derived from the 3-D solid angle, is given by a new expression. Numerical results clearly demonstrate the accuracy of this approach to predict the acoustic fields particularly on corners.