Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Input/Output Linearization for a Real-Time pH Control: Application on Basic Wastewater Neutralization by Carbon Dioxide in a Fed-Batch Bubble Column Reactor
Get PDFA model-based application for pH regulation in a pilot unit of wastewater treatment by carbon dioxide gas is presented. A reactor pH is an important factor to enhance the gas absorption of carbon dioxide bubbles in an alkaline wastewater, and it needs to operate within a tight pH range. Under a fed-batch operation mode, the reactor behavior has unstable dynamics resulting in a difficulty to achieve the pH target by manipulating the basic influent feed rate. To solve the problem, an input/output (I/O) linearization is applied because it provides excellent the setpoint trackability with a few numbers of tuning parameters required. The first principles approach is employed for reactor modeling. The model is then used in the I/O feedback formulation. Control performance is evaluated through a real-time implementation to track the desired pH target in comparison with a two-degree-of-freedom control scheme used as a compared case. The developed control system proficiently forces the output to the pH target and also improves the control performances
A New Landscape Classification Approach for Quantifying Spatial Pattern of Bac Kan Province, Vietnam
Get PDFLandscape theory and its application have played an important role in natural resources exploitation and environmental protection. Various classification approaches had been employed worldwide in landscape ecology studies. This paper had developed a new hierarchical landscape classification framework for quantifying spatial pattern of Bac Kan province. A landscape formation equation was applied with three natural factors (geology, topography, and soil) and cultural factor (land use). A multi-level segmentation technique with multiresolution segmentation algorithm was chosen to segment landscape units (patches) and to categorize landscape types at different levels. The results revealed that the landscape classification of Bac Kan province has 4 hierarchical levels. Level 4, which provided full details of spatial pattern based on geologic period, elevation, soil depth, and land use, had 315 landscape types. At this level, there are 8,427 landscape units mapped with a minimum and maximum areas of 0.02 km2 and 116.63 km2, respectively. A new Bac Kan landscape map at a scale of 1:100,000 along with 16 different attributes for each landscape unit was also produced. In conclusion, the framework of research methodology presented in this paper can be used as a guideline for landscape classification at provincial and national levels
Estimation of Groundwater Use Pattern and Distribution in the Coastal Mekong Delta, Vietnam via Socio-Economical Survey and Groundwater Modelling
Get PDFIn many provinces of Mekong delta, excessive groundwater extraction has resulted in many serious groundwater-related problems. To solve problems relevant to increasing water demand as well as other negative influence of groundwater depletion, an exigent question was raised whether at what time in future is the limits to local groundwater use reached? Hence, there is a need to know groundwater use (GWU) pattern and distribution in the study area for future groundwater management. In this study, firstly, the study used socio-economic data of Tra Vinh Province to classify groups of revenue, potential of water resources and population distributed in each district in order to design and conduct the socio-economic survey and to explore information relevant to GWU for each purpose. Secondly, the data set of 419 survey questionnaires per 9 surveyed communes were analysed by SPSS tool to estimate ratio of household using groundwater (RHHUG) for each purpose as well as average pumping rate (APR) per household for domestic use and per ha for agriculture use, respectively. Thirdly, the APRs were extended to propose the total GWU pattern and distribution during 2007-2016 by using socio-economic data of the province and expand to spatial distribution by using correlation with land surface temperature (LST) which was estimated from Landsat 8 images. Besides, the groundwater flow model of the study area was developed to verify the estimated amount of groundwater pumping (pattern and distribution) in the period. The study found that the annual GWU of Tra Vinh Province in 2016 was 347,793 m3/d in which two coastal districts occupied more than 50 percentages, i.e., about 188,551 m3/d. RHHUG increased from 2 to 3 times during the period of 2007 to 2016 in this area. LST distribution performed a good correlation (adj-R2 = 0.646) with GWU distribution in Tra Cu district. Results of groundwater modelling also showed that the discharge from aquifer (mainly pumping) was always higher than the recharge to aquifer
Chest Expansion Measurement in 3-Dimension by Using Accelerometers
Get PDFThe chest expansion measurement is a part of physical therapy to track the progress of rehabilitation for checking the performance of lungs. The chest expansion mechanism moves like pump handle and bucket handle. These two movements cause the chest move many directions. For tracking the chest movement in each direction, the MEMS accelerometers are used to measure acceleration in each axis. Consequently, acceleration is converted to displacement by double integration. The acceleration from accelerometer in each axis is affected from the earth gravity force. Thus, rotation matrix is used for compensating the earth gravity force. It can track the acceleration vectors while rotating. The known movement from robot is simulated similar the chest expansion. 60 sets of accelerometer data were collected from robot demonstration and were analyzed for testing the accuracy of sensor and algorithm. For the highest expansion, the chest expansion measurement must be performed while doing deep breathe inhale and exhale. The deep breath signal is a low frequency and there is high frequency noise. Therefore, a low-pass filter was used for eliminating high frequency noise. The accelerometers and VICON’s markers were placed together on the body. The displacement results from accelerometers were compared with the displacement of VICON motion analysis system to find the accuracy of our purposed device. The average error of 20 sets of acceleration data from accelerometers which referred with VICON motion analysis is 7.195±4.361 mm. Accelerometer result trend follows VICON motion analysis and corresponds to each other
Optimal Storage Locations for Warehouse Efficiency Improvement in a Haircare Manufacturer
Get PDFThis study aimed to enhance efficiency of raw materials warehouse in a case study haircare manufacturer in Thailand though identifying the optimal storage locations for materials locating at this raw materials warehouse. At the same time, it was our goal to increase capacity and improve utilization at internal raw materials warehouse in order to store some finished products at this internal warehouse instead of storing all of them at external public warehouse. As a result, the case study company can save storage cost of finished products at the external public warehouse. The key methodologies used to improve current raw materials warehouse were removing obsolete materials from warehouse, regrouping materials according to types, sizes, and turnover rate, reallocating space for each group of materials, considering beam height adjustment, and reassigning locations for each group of materials using optimization model. The results showed that capacity of raw materials warehouse was enhanced by 12.65%, picking distance was reduced by 51.9% compared to current situation, utilization was more balanced throughout warehouse and annual cost saving of 874,800 THB was obtained from locating some finished products at the internal raw materials warehouse. In addition, robustness of the proposed model was analyzed and contingency plan was developed for handling with over flow materials if over utilization occurs
Characteristics of Gridded Rainfall Data for Thailand from 1981–2017
Get PDFWe used a spatially interpolated gridded dataset produced by the Thai Meteorological Department (TMD) to explore long-term rainfall trends. We placed data from 1981–2017 into a 0.5° grid using the Kriging method. Long-term trends in maximum daily and monthly rainfall, and total annual rainfall, were analyzed using the nonparametric Mann–Kendall trend test. Chumphon, Lamphun, Nakhon, Sawan, and Buriram provinces exhibited significant positive trends in the annual maximum daily rainfall (p<0.05, p<0.01). The coastal area of Chachoengsao Province exhibited a significant negative trend (p<0.05). January rainfall showed a negative trend throughout Thailand. Annual rainfall showed a positive trend in many regions, especially in northern, northeastern, and southern areas. The eastern region exhibited a negative trend but statistical significance was not attained. The 10-, 30-, 50-, and 100-year daily rainfall probabilities were estimated using the Generalized Extreme Value method. The eastern side of the southern region exhibited remarkably high rainfall
Efficacy of a GPGPU-Acceleration to Inundation Flow Simulation in Tonle Sap Lake in Cambodia
Get PDFA new 2D numerical model is developed for a rapid computation of the seasonal inundation phenomena in Tonle Sap Lake in Cambodia. In order to overcome a huge computational cost for a prolonged analysis over an extensive area, the General-Purpose computing on Graphics Processing Units (GPGPU) technology is applied to the model. The developed model is applied to a solution of seasonal inundation process for the 154 days in 2002. Calculated result is compared with observational data and satellite remote sensing. It is found that the developed model seems to successfully reproduce reasonable progress/regress of inundation. A breakdown of the total elapsed time for the numerical analysis is considered in a detail. It is found that the GPGPU technology can accelerate the solution more than one hundred times faster by employing a simple rectangular mesh and coding to reduce a memory access overhead
Carbon Dioxide Capture in a Fixed Bed of Coconut Shell Activated Carbon Impregnated With Sodium Hydroxide: Effects of Carbon Pore Texture and Alkali Loading
Get PDFPerformance of CO2 adsorption was investigated in a fixed bed of coconut shell activated carbon impregnated with sodium hydroxide with emphasis on the effect of alkali loading and carbon pore texture. CO2 adsorption capacity increased with the increase of NaOH loading and passed through a maximum value at the optimum loading of 180 g NaOH/g carbon. This optimum loading appeared to be the same, independent of the surface area of activated carbon in the range of 766-1052 m2/g. A pore blocking phenomenon was proposed to account for the effect of alkali loading on the CO2 adsorption behavior. Empirical equations were also developed to correlate the breakthrough time, the adsorption capacity at breakthrough time and the equilibrium adsorption capacity with alkali loading and surface area of activated carbon. The breakthrough equation based on the LDF model was found to describe the experimental breakthrough data reasonably well. The transport of CO2 molecules in the pore structure of activated carbon to the adsorption sites is governed by the mechanism of surface diffusion and the surface diffusivity is about two orders of magnitude larger than the pore diffusivity
Comparative Structural Design for Pressure- and Temperature- Resistant Buildings with Loads Affecting Externally on Structures of Different Heights
Get PDFLoads from explosions can be classified as internal blast load and external blast load and these loads have great severity, continuity and rapidity. That is, explosions cause massive structural damage by exposing surrounding structures to extremely high pressure and temperature. Thus, structures at risk of explosive damage must be stronger than typical buildings in withstanding both ordinary loads and the additional pressure and temperature loads caused. Explosion-resistant structures are required in the petrochemical industry, explosive armories, power stations, and gas storage facilities, among others. This study aims to examine and compare the structural performance of two building of different heights, which are 5-floor and 2-floor, subject to three types of loads: (1) the pressure of 300 bars, (2) the temperature of 300 °C, and (3) the pressure of 300 bars combined with the temperature of 300 °C. The research analyzes three primary reinforced structures, namely columns, beams, and slabs, in terms of the parameters resulting from each scenario to determine a set of criteria for designing the structural components of the buildings to resist the external blasts
Enabling Technology and Proof-of-Concept Evaluation for RAN Architectural Migration toward 5G and Beyond Mobile Systems
Get PDFIn this paper, we address two major issues regarding architectural migration of radio access network (RAN). Firstly, an overview and explicit interpretation of how different enabling technologies over generations are brought up and coordinated for migration from a distributed, to a centralized, and then to a virtualized RAN for 5G and beyond cellular; and secondly, the proof-of-concept (PoC) evaluation to understand the feasibility of these enabling technologies, are addressed. In doing so, we first give an overview of major enabling technologies and discuss their impact on RAN migration. We then evaluate the PoC of major enabling technologies proposed mainly for 5G CRAN, namely functional split options, TDM-PON systems, and virtualization techniques using a mobile CORD based prototype in LTE systems with ideal fronthauls. PoC experimental results with split options 2 and 5 are presented and compared using TCP and UDP traffic. Experimentally, it is shown that the throughput improvement is significant for TCP as compared to UDP with virtualized BBUs, which are about 30%-40% and 40%-45% higher in mean throughputs respectively in downlink and uplink with split 5 than that with split 2. Finally, we point out the major experimental limitations of PoC and future research directions