Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Portable Fog Gateways for Resilient Sensors Data Aggregation in Internet-less Environment
Get PDFFog computing is gaining attention due to the potential of aggregating and processing time-sensitive data at the nearby intelligent gateways. It reduces the latency of sensors data aggregation and response time therefore, improve real-time action which is beneficial in environmental monitoring and early warning systems. However, deploying edge computing in Internet-less environment seems unpractical and the mobility of gateways is less focused in current literature. In this paper, we present a practical design of a portable gateways scheme for sensors data aggregation and processing in Internet-less environment. The proposed gateways can locate their geographical locations which can be automatically converted into location names at the central gateway. The proposed portable Fog Gateways are developed by using open-source hardware and integrated with Cloud database for data storage. Data processing techniques such as data parsing and Reverse Geocoding are conducted for reliable data transmission by using GSM/GPRS technology and geographical location name detection respectively. Finally, a case study has been conducted to evaluate the feasibility of our proposed Fog Gateways scheme in real-time application
Dependence of Catalyst Surface in Photocatalytic Degradation of Phenyl Urea Herbicides
Get PDFPhotocatalytic degradations of various contaminants using in-house synthesized catalysts have been generally reported, but the degradation intermediates formed are normally inconsistent. This issue is particularly important for the degradation of toxic compounds which may form intermediates with increased toxicity. This work resolves this issue by systematically investigating adsorption and photocatalytic degradation of diuron, linuron, and 3,4-dichloroaniline (DCA) on two forms of zinc oxide (ZnO), i.e., conventional particles with zinc- and oxygen-terminated polar surfaces, and nanorods with mixed-terminated non-polar surfaces. Experimental results indicate that both rate of degradation and degradation pathway depend upon the adsorption configuration of the compound undergoing the degradation onto the surface of the catalyst. The adsorption configuration is surface dependent. On polar surfaces, both aliphatic and aromatic sides of diuron and linuron molecules adsorb on the surface, allowing the attack of hydroxyl radicals on both ends. On the other hand, on non-polar surface, only the aliphatic chain adsorbs onto the surface, resulting in the hydroxyl radicals attack only on the aliphatic side. The structure of the catalyst is therefore a crucial factor determining the dominant degradation pathway
Influence of Soft Magnetic Materials Application to Squirrel Cage Induction Motor Design and Performance
Get PDFMost of the electrical machines design studies found in literature lie on the concept that the design under investigation (and optimization) focuses mainly on the geometrical aspects of the machine and thus takes into account only a certain ferromagnetic material (i.e. iron) for its parts. These studies, give little or no information about the influence of material alternatives on the same (and optimized) design. From a manufacturer's point of view though, this information is crucial especially nowadays that there are a lot of commercially available materials in the market. In this context, this paper presents the results of a research project in the design stage of an energy efficient three phase squirrel cage induction motor (SCIM), by investigating the effects of several soft magnetic materials (adopted for its stator and/or its rotor parts) on multiple quantities of primary concern such as: efficiency, power factor, output torque, losses, weight and cost. After a brief proposed design procedure, a total of twenty-two different materials from recent manufacturers' data were examined. Also, the main electromagnetic analysis was performed through commercial analysis software. Simple ranking methods are also proposed here and the results obtained are then thoroughly discussed and commented
Investigating Lateritic Soil Properties and Impacts from Quarrying Activity on Communities in Southern Thailand: A Case Study
Get PDFThis paper details the impact arising from the lateritic soil quarrying activity in many communities within Songkhla province of Southern Thailand. The affected communities of Ban Khuan Chong, Ban Huay Oan and Ban Thung Don were selected as target areas for the study based on the suitability of their active quarry sizes and locations which are conspicuous on the aerial photographs of Google Maps, and where permission to collect data was forthcoming from the quarry operators. Assessments were made to determine the extent of impact on the communities in terms of the environment, people's health, and effects on transport infrastructure. Findings from the study are shown on the website: http://techno.nstru .ac.th/piti/project in order to help promote responsible quarrying and use of lateritic soil in the construction business. In addition to details of the likely impacts from various types of soil excavation, the website features a database of quarry sites in the province as well as engineering properties of the soils therefrom
A Comparative Analysis of Weed Images Classification Approaches in Vegetables Crops
Get PDFThis paper exposes a comparative analysis of three weed classification strategies based on area and texture features over images of vegetable crops, focus on provide a technological tool to support farmers in their maintenance tasks. The classification alternatives embrace a basic approach which defines an umbral according to scene features, indeed, a detection with a certain degree of uncertainty on the decision region is purposed and a rigid boundary decision arrangement are exposed. A first mode carry out an unsupervised learning, it uses area and color features with a practical thresholding classifier to differentiate between weed and vegetable classes, the following two, extracts statistical measures of autocorrelation, contrast, correlation and others, from grey level co-occurrence matrices to calculate texture features, next, a principal component analysis is made for dimensionality reduction. These patterns serve as basis for training K-Nearest Neighbor and Support Vector Machine classifiers. The algorithms performance is measured calculating sensitivity (SN), specificity (SP), positive and negative predicted values (PPV and NPV), also, the execution time is stored and tabulated in order to evaluate the proposed methods. Finally, the results show a similar performance of correct classification over 90 and 80% on SN and SP indices respectively, however, approaches present a clear difference in execution time respect of train an evaluation stages.This paper exposes a comparative analysis of three weed classification strategies based on area and texture features over images of vegetable crops, focus on provide a technological tool to support farmers in their maintenance tasks. The classification alternatives embrace a basic approach which defines an umbral according to scene features, indeed, a detection with a certain degree of uncertainty on the decision region is purposed and a rigid boundary decision arrangement are exposed. A first mode carry out an unsupervised learning, it uses area and color features with a practical thresholding classifier to differentiate between weed and vegetable classes, the following two, extracts statistical measures of autocorrelation, contrast, correlation and others, from grey level co-occurrence matrices to calculate texture features, next, a principal component analysis is made for dimensionality reduction. These patterns serve as basis for training K-Nearest Neighbor and Support Vector Machine classifiers. The algorithms performance is measured calculating sensitivity (SN), specificity (SP), positive and negative predicted values (PPV and NPV), also, the execution time is stored and tabulated in order to evaluate the proposed methods. Finally, the results show a similar performance of correct classification over 90 and 80% on SN and SP indices respectively, however, approaches present a clear difference in execution time respect of train an evaluation stages
Mixed Zero-Inflation Method and Probability Distribution in Fitting Daily Rainfall Data
Get PDFIn hydrological processes, rainfall is one of the important components of water supply for human life. We considered how well the statistical distribution simulates rainfall intensity. We propose an asymmetric statistical probability distribution joined by zero-inflated to fit the daily continuous record of rainfall data in Thailand. The candidate statistical probabilities are General Pareto, Exponential, Beta, Gamma, Generalize extreme value, Extreme Value, Normal, Lognormal, Weibull and Rayleigh distribution. The daily data from 123 rain gauges in Thailand collected and removed in a given year, using the null value. The statistical distributions estimated on the statistical coefficient, using the maximum likelihood estimation (MLE) method and resulted in a cumulative density function (CDF). The CDF compared to the CDF of observed data that estimated, using Kaplan-Meier algorithm. The comparisons were evaluated by Goodness of fit (GOF) in 3 null hypothesis tests (Kolmogorov-Smirnov, Anderson-Darling and Chi-Square test). The best fit distribution was identified by minimum residual (R) index and maximum correlation (Cor) index based on difference value between the estimated and observed data. The Weibull distribution matched to the 118 rain gauges while 5 rain gauges were best fitted by the Gamma distribution.In hydrological processes, rainfall is one of the important components of water supply for human life. We considered how well the statistical distribution simulates rainfall intensity. We propose an asymmetric statistical probability distribution joined by zero-inflated to fit the daily continuous record of rainfall data in Thailand. The candidate statistical probabilities are General Pareto, Exponential, Beta, Gamma, Generalize extreme value, Extreme Value, Normal, Lognormal, Weibull and Rayleigh distribution. The daily data from 123 rain gauges in Thailand collected and removed in a given year, using the null value. The statistical distributions estimated on the statistical coefficient, using the maximum likelihood estimation (MLE) method and resulted in a cumulative density function (CDF). The CDF compared to the CDF of observed data that estimated, using Kaplan-Meier algorithm. The comparisons were evaluated by Goodness of fit (GOF) in 3 null hypothesis tests (Kolmogorov-Smirnov, Anderson-Darling and Chi-Square test). The best fit distribution was identified by minimum residual (R) index and maximum correlation (Cor) index based on difference value between the estimated and observed data. The Weibull distribution matched to the 118 rain gauges while 5 rain gauges were best fitted by the Gamma distribution
Two-Dimensional CFD Simulation of Reducing Operating Pressure Effect on the System Hydrodynamics in a Downer Reactor
Get PDFThe effect of the system hydrodynamics in a circulating fluidized bed downer (CFBD) reactor with a reducing operating pressure and solid mass flux on the hydrodynamics in a downer reactor were evaluated using a two-dimensional computational fluid dynamics simulation. Five low operating pressure conditions (0.90 to 0.99 atm) and four different solid mass fluxes (250 to 1,000 kg/m2 s) were explored. The simulation results demonstrated that the CFBD reactor had a higher mean free path when operated with a low solid mass flux than with a high solid mass flux. Moreover, a large difference between the operating and atmospheric pressures induced a high system turbulence or oscillation. The CFBD reactor with hydrodynamic fluctuation showed a good solid circulation between the gas and solid particles, as reflected by the solid volume fraction and velocities and granular temperature. These phenomena will be suitable for the chemical reaction systems. Therefore, a suitable solid mass flux was in the range of 500 to 750 kg/m2 s for all operating pressuresThe effect of the system hydrodynamics in a circulating fluidized bed downer (CFBD) reactor with a reducing operating pressure and solid mass flux on the hydrodynamics in a downer reactor were evaluated using a two-dimensional computational fluid dynamics simulation. Five low operating pressure conditions (0.90 to 0.99 atm) and four different solid mass fluxes (250 to 1,000 kg/m2 s) were explored. The simulation results demonstrated that the CFBD reactor had a higher mean free path when operated with a low solid mass flux than with a high solid mass flux. Moreover, a large difference between the operating and atmospheric pressures induced a high system turbulence or oscillation. The CFBD reactor with hydrodynamic fluctuation showed a good solid circulation between the gas and solid particles, as reflected by the solid volume fraction and velocities and granular temperature. These phenomena will be suitable for the chemical reaction systems. Therefore, a suitable solid mass flux was in the range of 500 to 750 kg/m2 s for all operating pressure
Preliminary Study for Design Core of Nuclear Research Reactor of TRIGA Bandung Using Fuel Element Plate MTR
Get PDFThe nuclear reactor has two types of power reactors based on the function that is used as electrical energy and research reactors and radioisotope used as a producer of nuclear science and technology research. Indonesia has three research reactors are two types of TRIGA research reactor in Bandung with a power of 2 MW and in Yogyakarta with a power of 100 kW and a research reactor in PUSPIPTEK Serpong with nominal power of 30 MW. For the second fuel elements TRIGA type reactor that is currently using elements of cylindrical material, while the fuel elements RSG-GAS reactor in Serpong-shaped plate. Reactor TRIGA Bandung is a reactor that can be used to predict the buffer reactor. However, this reactor has a problem because of the limited number of existing fuel element. Meanwhile, production of TRIGA fuel elements abroad already closed. Given that Indonesia has the ability to produce nuclear fuel elements for research reactors fueled plate it is proposed to modify the reactor core of TRIGA Bandung of the terrace patio made from a cylinder into fuel plates. In this research will be studied more deeply about aspects thermal-hydraulics TRIGA research reactor using fuel elements plate replacement to cylinder fuel element. The method used is the modeling and simulation of the fuel element plate using porous media and non-porous media with the program of CFD Code. Results of the simulation show that the phenomenon of flow and temperature distribution closer to the comparison of the design elements used fuel plate. So later this plate fuel elements can be used in a nuclear reactor core TRIGA research Bandung, Indonesia.The nuclear reactor has two types of power reactors based on the function that is used as electrical energy and research reactors and radioisotope used as a producer of nuclear science and technology research. Indonesia has three research reactors are two types of TRIGA research reactor in Bandung with a power of 2 MW and in Yogyakarta with a power of 100 kW and a research reactor in PUSPIPTEK Serpong with nominal power of 30 MW. For the second fuel elements TRIGA type reactor that is currently using elements of cylindrical material, while the fuel elements RSG-GAS reactor in Serpong-shaped plate. Reactor TRIGA Bandung is a reactor that can be used to predict the buffer reactor. However, this reactor has a problem because of the limited number of existing fuel element. Meanwhile, production of TRIGA fuel elements abroad already closed. Given that Indonesia has the ability to produce nuclear fuel elements for research reactors fueled plate it is proposed to modify the reactor core of TRIGA Bandung of the terrace patio made from a cylinder into fuel plates. In this research will be studied more deeply about aspects thermal-hydraulics TRIGA research reactor using fuel elements plate replacement to cylinder fuel element. The method used is the modeling and simulation of the fuel element plate using porous media and non-porous media with the program of CFD Code. Results of the simulation show that the phenomenon of flow and temperature distribution closer to the comparison of the design elements used fuel plate. So later this plate fuel elements can be used in a nuclear reactor core TRIGA research Bandung, Indonesia
Transient Modeling of Tubular-Designed IIR-SOFC Fueled by Methane, Methanol, and Ethanol
Get PDFIt is known that the heating rate during starting-up of Solid Oxide Fuel Cell (SOFC) plays an important role of system performance and lifetime. In the present work, an axial 2-D tubular Indirect Internal Reforming SOFC (IIR-SOFC) model fueled by methane, methanol, and ethanol was developed with the aim of predicting the system temperature gradient during the starting-up period. All predicted results was calculated by using COMSOL®. The system was also compared with typical SOFC fueled by hydrogen. It was found that hydrogen heating gas required the lowest time to achieve the steady state (around 2 minutes) with the highest heating rate 0.93 K/s, which is not compatible for the thermal stress of SOFC material. The uses of methane, methanol, and ethanol as primary fuel can enhance compatible heating rate with the cell material, from which IIR-SOFC fueled by methanol is the best option in terms of its slow heating rate and high system efficiency. It is noted that the effects of inlet steam/carbon (S/C) ratio and gas flow pattern were also studied. It was observed that changing in S/C ratio is not significantly influence to temperature behaviors of the system. Meanwhile, IIR-SOFC with co-flow pattern provided smoother temperature gradient along cell and higher power density at steady state condition than that with counter-flow pattern.It is known that the heating rate during starting-up of Solid Oxide Fuel Cell (SOFC) plays an important role of system performance and lifetime. In the present work, an axial 2-D tubular Indirect Internal Reforming SOFC (IIR-SOFC) model fueled by methane, methanol, and ethanol was developed with the aim of predicting the system temperature gradient during the starting-up period. All predicted results was calculated by using COMSOL®. The system was also compared with typical SOFC fueled by hydrogen. It was found that hydrogen heating gas required the lowest time to achieve the steady state (around 2 minutes) with the highest heating rate 0.93 K/s, which is not compatible for the thermal stress of SOFC material. The uses of methane, methanol, and ethanol as primary fuel can enhance compatible heating rate with the cell material, from which IIR-SOFC fueled by methanol is the best option in terms of its slow heating rate and high system efficiency. It is noted that the effects of inlet steam/carbon (S/C) ratio and gas flow pattern were also studied. It was observed that changing in S/C ratio is not significantly influence to temperature behaviors of the system. Meanwhile, IIR-SOFC with co-flow pattern provided smoother temperature gradient along cell and higher power density at steady state condition than that with counter-flow pattern
Modeling and Simulation of UWB Wave Propagation for Early Detection of Breast Tumors in Cancer Dielectric Imaging Systems
Get PDFIn this paper we have proposed an analytical body (breast-tissue) propagation model in terms of scattering parameters towards the design goal of a suitable ultra-wide band, (UWB) transceiver for early breast tumor detection. The scattering parameters are reflection (Γ) and transmission coefficients (Τ). We considered a heterogeneous breast model consisting of skin, adipose and glandular tissues as body (breast) channel and planar wave to propagate through it for UWB frequency range. A tumor layer was also considered as an inner layer to investigate tumorous tissue effects. Effective dielectric properties and scattering parameters (through reflected/ scattered or forward transmitted signals) for the whole breast were determined. Due to dispersive nature of heterogeneous breast, Γ and T vary with frequency; showing their decisive nature for a particular center frequency of the UWB transceiver systems. For 4.5 GHz center frequency UWB system, the back propagated (reflected/ scattered) signals showed approximately 63.3% higher amplitude than forward propagated signals for the breast channel with tumor.In this paper, we have proposed an analytical body (breast-tissue) propagation model in terms of scattering parameters towards the design goal of a suitable ultra-wide band, (UWB) transceiver for early breast tumor detection. The scattering parameters are reflection (and transmission coefficients (Τ). We considered a heterogeneous breast model consisting of skin, adipose and glandular tissues as body (breast) channel and planar wave to propagate through it for UWB frequency range. A tumor layer was also considered as an inner layer to investigate tumorous tissue effects. Effective dielectric properties and scattering parameters (through reflected/ scattered or forward transmitted signals) for the whole breast were determined. Due to dispersive nature of heterogeneous breast, Γ and T vary with frequency; showing their decisive nature for a particular center frequency of the UWB transceiver systems. In case of 2.0 GHZ and 4.5 GHz center frequency UWB system, the back propagated (reflected/ scattered) signals showed approximately 45.45% and 63.3% respectively higher amplitude than forward propagated signals for the breast channel with tumor, indicating high value of dispersion present in human breast tissues