Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Mixing-Performance Evaluation of a Multiple Dilution Microfluidic Chip for a Human Serum Dilution Process
Get PDFThis paper is aimed to propose a numerically designed multiple dilution microfluidic chip that can simultaneously deliver several serum dilutions in parallel. The passive mixing scheme is selected for dilution and achieved by the serpentine mixing channel in which Dean vortices are induced to increase the contact area and time for better diffusion. The mixing performance at the exit of this dilution chip is numerically evaluated using five commonly-used mixing indices with the goal that the homogeneity of the mixture over the exit cross-sectional area of the mixing channel must be greater than 93.319% to fulfill the six-sigma quality control
A Solution of Traffic Congestion for Ko Chang Piers through Applying Access Fee
Get PDFKo Chang, one of the main island attractions of Thailand, is suffering from congestion at its ferry piers due to the great flocks of tourists. Due to the low vehicle-carrying capacity of the ferry, the bottlenecks are observed especially over long weekends. Over volume of private cars that are cause of negative impact to tourist destination is overtourism phenomenon. The problem could be alleviated if the tourists could be encouraged to park their cars at the main land piers and walk on to the ferry. This study aims to find out the Thai tourist mode choice preference and develops a binary logit model with its objective to alleviate the congestion via the demand management strategies. The results show that the monetary cost and wait time in the queue are the primary and secondary factors affecting the tourist’s decision. It is also shown that almost half of the tourists would leave their cars on the mainland if 500-baht charge is applied with the 3 hour wait
Optimization for Biodiesel Production by Transesterification with Electric Fields
Get PDFThe objective of this research is to study optimization for biodiesel production from transesterification with electric fields. The catalyst in this reaction is potassium hydroxide (KOH) at 1% weight (wt). The molar ratio is 6:1. Two factors at three levels are considered using the response surface method. The first factor, the intensity of the electric field, is set at 85 volts/centimeter (V/cm), 170 V/cm, and 255 V/cm. The second factor, the retention time of the electric fields, is set at 2 minutes (min), 6 min, and 10 min. In the experiments, the best yields are produced from an electric fields intensity of 85 V/cm, with the electric field’s retention time of 2 min. The calculated and experimental results are 98.26% and 98.41%, respectively
Nano-Zinc Oxide-Doped Activated Carbon from Popped Rice and Its Application for Feed Additive
Get PDFThis study synthesized nano-zinc oxide (ZnO)-doped activated carbon based on popped rice. The rice was prepared by heating unmilled rice using hot air to create a porous structure. The popped rice was chemically activated using zinc chloride (ZnCl2) solution at impregnation ratios of ZnCl2 to popped rice (1:1 and 1:2). Pyrolysis was conducted under constant nitrogen flow by raising the temperature at a heating rate of 10°C/min to 800°C and maintaining this temperature for 1 h. The adsorption properties of the activated carbon were investigated using methylene blue (MB). The results of ultraviolet-visible spectroscopy (UV-Vis) showed the prepared activated carbon had a high adsorption capacity of MB that could be compared to that of commercial activated carbon. The structure and morphology of the activated carbon containing ZnO nanoparticles were characterized using raman spectroscopy, field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM)/energy-dispersive spectroscopy (EDS). The specific surface area and porosity were analyzed using the Brunauer-Emmett-Teller (BET) method. The ability to bind 3 different types of mycotoxins was evaluated. The outcome indicates that high surface-area-activated carbon with ZnO nanoparticles exhibited the potential to bind aflatoxin B1, zearalenone, and fumonisin B1, which could be used as an animal feed additive
In-situ Observation of h-BN Formation on the Surface of Weld Dissimilar Joint Steels
Get PDFIn-situ observation of h-BN formation by surface precipitation on the surface of joined dissimilar steels is presented. Because the substrate consists of two different types of steels, different growth behaviors can be seen on different sides and also in the middle of the weld interface. This observation demonstrates that formations of 2D materials can occur on surfaces of steels under suitable conditions e.g. temperature, microstructures and concentrations of impurities. Characterizations by electron microscopy and synchrotron spectroscopy technics confirm that h-BN crystals that appear on the surface after annealing are of similar quality to those prepared by other methods such as chemical vapor deposition. Moreover, real-time observation during sample temperature swing above and below the phase transition temperature of Fe shows that h-BN islands reversibly form and dissociate on the surface. The results show that the formation of h-BN on steels is reversible and the analysis suggests that the process is likely affected by structural change of the steels near the phase transition temperature, which in-turn drives the diffusions of B and N atoms back and forth between surface and bulk
Vermicompost from Chula Zero Waste Cup and Rain Tree (Samanea Saman) Leaves
Get PDFTo recycle waste including paper-cup waste and rain tree leaves, the objective of this study was to determine the appropriate ratio of paper-cup waste (Chula Zero Waste Cup) and rain tree leaves in a vermicomposting process that uses the earthworm species Eudrillus eageniae and combines cow dung and coffee grounds as bulking agents. The vermicomposting in this study was conducted for 60 days. From the analysis of physical and chemical properties, it was found that all treatments (T1 to T5) on the final vermicomposting had the values of pH, EC and C/N ratio in the range of 8.16–8.41, 1.24–1.55 dS/m and 2.36–2.71 respectively. The total organic carbon content and total organic matter content had the highest value in treatment: 4 (T4) was 33.47 ± 0.56% and 57.56 ± 0.96%, respectively, while the lowest value in treatment 3 (T3) was 32.09 ± 0.61% and 55.20 ± 1.06%, respectively. For the primary macronutrients, including total Kjeldahl nitrogen content available, phosphorus and exchangeable potassium content, the study found that the total Kjeldahl nitrogen content had the highest in treatment 4 (T4) and the lowest in treatment 1 (T1), with the value of 14.17 ± 0.46% and 12.24 ± 0.48%, respectively. Available phosphorus content had the highest in treatment 1 (T1) and the lowest in treatment 5 (T5), with the value of 1,418.08 ± 305.45 ppm and 472.69 ± 57.98 ppm, respectively. Exchangeable potassium content had the highest in treatment 1 (T1) and the lowest in treatment 3 (T3), with the value of 8,146.81 ± 739.40 ppm and 3,861.98 ± 1,024.56 ppm, respectively. In addition, the seed germination test found that the highest value in treatment 1 (T1) was 45.00 ± 10.00%, while the lowest value in treatment 2 (T2) was 31.67 ± 23.63%. In comparing these results to the compost quality standards of the Department of Agriculture (2005), we conclude that T1 to T5 can help improve the physical properties of the soil as an alternative method for waste utilization by vermicomposting
Improved Development Cycle for 8-bit FPGA-Based Soft-Macros Targeting Complex Algorithms
Get PDFDeveloping complex algorithms on 8-bit processors without proper development tools is challenging. This paper integrates a series of novel techniques to improve the development cycle for 8-bit soft-macros such as Xilinx PicoBlaze. The improvements proposed in this paper reduce development time significantly by eliminating the required resynthesis of the whole design upon HDL source code changes. Additionally, a technique is proposed to increase the maximum supported data memory size for PicoBlaze which facilitates development of complex algorithms. Also, a general verification technique is proposed based on a series of testbenches that perform code verification using comparison method. The proposed testbench scenario integrates “Inter-Processor Communication (IPC), shared memory, and interrupt” concepts that lays out a guideline for FPGA developers to verify their own designs using the proposed method. The proposed development cycle relies on a chip that has Programmable Logic (PL) fabric (to hold the soft processor) alongside of a hardened processor (to be used as algorithm verifier), therefore, a Xilinx Zynq Ultrascale+ MPSoC is chosen which has a hardened ARM processor. The development cycle proposed in this paper targets the PicoBlaze, but it can be easily ported to other FPGA macros such as Lattice Mico8, or any non-Xilinx FPGA macros
Microbial Reduction of Bitter Melon (Momordica charantia L.) and Chan Khao (Tarenna hoaensis Pitard) Herb Powder by Dielectric Barrier Discharge Plasma for Food Sanitary
Get PDFThe influence of air plasma treatment on microbial inactivation contaminants in bitter melon (Momordica charantia L.) and Chan Khao (Tarenna hoaensis Pitard) powders, obtained from the local retail market in Nakhonnayok, has been investigated. The dielectric barrier discharge (DBD) air plasma model has been designed for in-package treatment by using a neon transformer. From the microbial analysis, there were high amounts of total aerobic plate count (TPC) as well as total yeast and mold counts (TYM) contaminants in both samples. It could be confirmed that the DBD air plasma treatment has a positive effect on microorganism reduction. Moreover, the color of air plasma-treated powders has still been chiefly preserved after the treatment process. The kinetics microbial inactivation process in this study has been found to be a single-slope survivor curve since the reduction rate is linear and increased with treatment time. The TPC and TYM concentration in the plasma-treated samples could be decreased to microbiologically qualify for the acceptance criteria of herbal drug preparations as indicated in the Thai Pharmacopoeia Volume I and II Supplement 2005 standard (TP Supplement 2005)
Design of 2D-Lattice Plates by Weight Efficiency
Get PDFIn this study, a method to design 2D-lattice plates, based on their weight efficiency, is proposed. The 2D-lattice plates considered in this study are made up of Euler-Bernoulli beams and can be modeled as homogeneous orthotropic Kirchhoff plates, derived by the strain-energy-based homogenization method. The weight efficiency of 2D-lattice plates is evaluated using relationships between their effective rigidities and area weight densities. The proposed design method is developed with these relationships. The closed-form effective rigidities of 2D-lattice plates, derived by the strain-energy-based homogenization method, are utilized as convenient design formulas for the proposed design method. A generic symbolic finite element program, written in MATLAB, is used to determine the closed-form solutions of effective properties that include the effective elastic constants, the effective rigidities, and the relationships between the effective rigidities and the area weight densities of 2D-lattice plates. Example design graphs, created by the obtained closed-form solutions, for 2D-lattice plates with different unit cells are presented and discussed. In addition, the usefulness of the obtained weight efficiency is also demonstrated via analysis of 2D-lattice plates with different unit-cell patterns
Distributed Model Reference Adaptive Control for Vehicle Platoons with Uncertain Dynamics
Get PDFThis paper proposes a distributed model reference adaptive controller (DMRAC) for vehicle platoons with constant spacing policy, subjected to uncertainty in control effectiveness and inertial time lag. It formulates the uncertain vehicle dynamics as a matched uncertainty, and is applicable for both directed and undirected topologies. The directed topology must contain at least one spanning tree with the leader as a root node, while the undirected topology must be static and connected with at least one follower receiving information from the leader. The proposed control structure consists of a reference model and a main control system. The reference model is a closed-loop system constructed from the nominal model of each follower vehicle and a reference control signal. The main control system consists of a nominal control signal based on cooperative state feedback and an adaptive term. The nominal control signal allows the followers cooperatively track the leader, while the adaptive term suppresses the effects of uncertainties. Stability analysis shows that global tracking errors with respect to the reference model and with respect to the leader are asymptotically stable. The states of all followers synchronize to both the reference and leader states. Moreover, with the existence of unknown external disturbances, the global tracking errors remain uniformly ultimately bounded. The performance of the controlled system is verified through the simulations and validates the efficacy of the proposed controller