Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Enhancement of Efficiency and Thermal Comfort in a Passenger Car Cabin Using Spanwise Inlet Vents
Get PDFEnsuring thermal comfort in car passenger cabins has been a sustained area of interest, both for automobile manufacturers and HVAC engineers alike. Towards this end, the four-channel inlet system appears to be the most common design among a majority of commercial vehicles. However, some recent studies indicate a lack of homogeneity due to flow transition with consequent effects on thermal distribution, leading to passenger dissatisfaction and discomfort. Thus, the current paper presents an alternative design for inlet vents of automobile passenger cabins for ensuring proper airflow and thermal distributions. The modified inlet design ensures a homogeneous circulation of air inside the car cabin, leading to reduced sensitization due to the localized cooling effect. The proposed ventilation design constitutes a high aspect ratio spanwise inlet vent that extends along the entire span of the dashboard. The computational simulations have been conducted using Fluent software package from ANSYS for the transient case and the resulting flow and thermal distributions are compared for ensuring thermal homogeneity as per ASHRAE standards for twelve pre-defined crucial locations in the passenger cabin. Our study indicates that the modified inlet vent design results in a faster temperature pull down, better flow homogeneity, and a greater heat recovery efficiency over the baseline design
Spatial Interpolation of SPT with Artificial Neural Network
Get PDFIn large infrastructure projects, initial geotechnical investigation is conducted at large spacing (~ 100m to 250m), in which SPT is the common test performed while dynamic tests are limited in number. The preliminary planning and design of the buildings are performed based on this information. Hence, estimate of dynamic properties of soil (say, shear wave velocity) at building locations becomes necessary. This can be performed by estimation of SPT at building locations, by interpolation from borehole locations, and thereafter using correlation expressions for estimating shear wave velocity at building location. Interpolation of SPT has been handled earlier in literature with statistical and geospatial techniques. In this article, an artificial intelligence technique, namely, artificial neural network (ANN) is explored for addressing this problem. ANN allows multiple degrees of freedom to data and optimizes weights and biases of the network to yield the best possible estimates of the desired output, in this case, the SPT at intermediate locations. ANN is known to be robust in handling data with noise and thus would be suitable for this application. Five neighbouring points were found suitable for efficient and accurate spatial interpolation of SPT using ANN with two to three neurons in one hidden layer. The performance was very good (correlation higher than 0.9 and errors lower than 2) and better than the geo-statistical approaches reported in literature (correlation lower than 0.9 and errors higher than 6). Within the limits of the study, the number of degrees of freedom (varying from 9 to 37) of the ANN did not affect its generalization capability
Non-Linear Site Response Analysis of Bangkok Subsoils Due to Earthquakes Triggered by Three Pagodas Fault
Get PDFSome responses to the remote earthquakes can be possibly felt by people in Bangkok. It indicates that there is seismic wave amplification during the earthquakes. The geological condition and the vibration intensity of the ground are the main factors of the amplification. In this study, the site-specific investigation was conducted in Bangkok including the boring log and shear wave velocity measurement. Analysis of non-linear seismic wave propagation were performed for each studied site. Model of Next Generation Attenuation (NGA) is used to ground motion from the earthquake under the activity of Three Pagodas Fault on the eastern Thailand bordered with Myanmar. The input motions were obtained from the database of Pacific Earthquake Engineering Research (PEER). The key results of ground motion characteristic are reported in this study. In general, the results show the effect of the motion due to earthquake to Bangkok subsoil. The investigated sites could undergo amplification during the earthquake under the scenario of Three Pagodas Fault. The results also suggest the people to consider the earthquake impact which is possibly triggered by the activity of Three Pagodas Fault
Development of Lightweight Concrete Interlocking Block Panel with Water Treatment Sludge and Expanded Metal Ferrocement
Get PDFAn innovative lightweight concrete interlocking block panel was developed to improve the lateral resistance of the infilled frame with green construction material. The water treatment sludge obtained from Bang Khen water treatment plants was employed to replace the fine aggregate. The lightweight concrete interlocking block panel was strengthened with ferrocement technique and expanded metal sheet. Three sets of the strengthened block panels with various sizes of expanded mental were investigated: concrete block panel, interlocking block panel with thin bed adhesive mortar, interlocking block panel with thick bed cement mortar. The concrete with mixed proportion of cement, sand, water, foaming agent, and sludge of 1:0.70:0.60:0.006:0.30 by weight was suitable for producing the lightweight concrete block according to the Thai Industrial Standard. The compressive strength test of masonry prisms and the diagonal tension (shear) test were conducted for the three sets of the strengthened block panels. The test results reveal that the interlocking block was superior to the conventional concrete block in terms of strength and ductility capacity due to the effect of interlocking between the block. The shear key with thick bed cement mortar is more effective than the thin bed adhesive mortar typically used in the construction of lightweight concrete
The Visual and Thermal Impact of Skylight Design on the Interior Space of an Educational Building in a Hot Climate
Get PDFSkylights have been among the important devices in architecture for providing sufficient daylight in an interior space. The design of a skylight, in terms of shape, orientation, and glazing specification has a great visual and thermal impact on any internal space, and thus on the choice for its optimum design. This study evaluates the daylight factor, glare and cooling loads for different designs of skylight and compares them with one another to select the best design among them. In addition to the base skylight-free case, twelve cases, categorized into three groups, were analyzed and compared. The groups, named A, B, and C, have sets of fixed parameters that differ from one group to another. The cases in Group A showed a sharp increment in cooling loads, which became significantly higher than the other two groups had, although the lighting levels were not necessarily so. Groups B and C showed varying increments in lighting levels, while the cooling loads were relatively close. Case B-4 was considered the best among the twelve studied cases
Public Planner's Perception of the Community Participation in Planning and Operational Decision-Making in Iskandar Malaysia
Get PDFRhetorically, effective community participation in urban planning helps the local planning authority in making a better decision, hence provided a sustainable and quality living environment to the community. The allocation for the community to participate in urban planning in Peninsular Malaysia is highlighted in the Town and Country Planning Act 1976 (Act 172). This study attempts to examine the effectiveness of community participation in planning and operational decision-making in Iskandar Malaysia. Iskandar Malaysia comprises of four local planning authorities that are responsible for governing the spatial planning in the region. Thus, it leads to the questions; what constitutes the effectiveness of community participation in the planning process? To what extent does the current participatory process offer a genuine opportunity to the community to incorporate their interest in the planning and operational decisions? This phenomenological study used thematic analysis to evaluate the insight claimed by selected public planners as the key-informants using the in-depth interview as the method for data collection. Following the 12 interviews conducted; a total of 37 themes and 68 sub-themes are transpired. A table is used to presents the factors that influence the effectiveness of community participation in Iskandar Malaysia. The findings suggested that public planners in Iskandar Malaysia believed the effectiveness of community participation in the region is significantly associated with the operational compared to structural and cultural dimensions of the process, hence hinder the capability of the community to access to genuine participation avenue
Sensitivity Analysis by the 2k Factorial Experimental Design of CO2 Capture with Amine Gas Treating Process Using Aspen Plus
Get PDFIt is well-known that CO2 capture with amine treating process has been used and developed in industry to purify the off-gas from the process. Nowadays, the simulation via computer software is one of the most effective tools to improve and optimize the existing process because there is no environmental effect and uses lower cost compared to the experiments. Generally, for sensitivity analysis, the parameters are studied individually without considering the interaction effects between parameters. In this study, the equilibrium model of CO2 capture by monoethanolamine (MEA) pilot plant was modelled using Aspen Plus by ENRTL-RK thermodynamics property model. A sensitivity analysis with the 2k factorial experimental design was performed. The main and interaction effects of five parameters (which are liquid-gas mass ratio (L/G), sour gas temperature, lean MEA temperature, lean MEA concentration and CO2 concentration in sour gas) were then investigated. From the sensitivity analysis with the 2k factorial experimental design, liquid-gas mass ratio contributed 75.82% to CO2 removal efficiency; while CO2 concentration in sour gas and liquid-gas mass ratio (L/G) occupied 29.14% and 17.36% to CO2 removal efficiency and specific heat duty at the reboiler, respectively
Convex Optimization Approach to Multi-Objective Design of Two-Stage Compensators for Linear Systems
Get PDFThe previous design of two-stage compensators of linear systems was focused on the stabilization and low sensitivity. However, it has not considered the time-domain performance of the closed-loop system, especially, reference tracking. This paper aims to propose the design method of the two-stage compensators that additionally achieves good transient response. Applying Q-parameterization to the standard control system can formulate the two-stage compensator design as a convex optimization problem. The infinite dimensional problem is transformed into a finite dimensional problem by Ritz approximation. Finally, the convex optimization is efficiently solved to give the optimal controller. The numerical results show that the proposed design method on the second order benchmark problem and the first order plus time delay system improves the time-domain performance while the closed-loop system is stable and the influence of disturbance to output is attenuated
Determining Bus Stop Locations using Deep Learning and Time Filtering
Get PDFThis paper presents an intelligent bus stop determination from bus Global Positioning System (GPS) trajectories. A mixture of deep neural networks and a time filtering algorithm is used in the proposed algorithm. A deep neural network uses the speed histogram and azimuth angle at each location as input features. A deep neural networks consists of the convolutional neural networks (CNN), fully connected networks, and bidirectional Long-Short Term Memory (LSTM) networks. It predicts the soft decisions of bus stops at all locations along the route. The time filtering technique was adopted to refine the results obtained from the LSTM network. The time histograms of all locations was built where the high potential timestamps are extracted. Then, a linear regression is used to produce an approximate reliable timestamp. Each time distribution can be derived using data updated at that time slot and compared to a reference distribution. Locations are predicted as bus stop locations when timestamp distributions close to the reference distributions. Our technique was tested on real bus service GPS data from National Science and Technology Development Agency (NATDA, Thailand). The proposed method can outperform other existing bus stop detection systems
Fuzzy Analytical Hierarchy Process for Supplier Selection: A Case Study in An Electronic Component Manufacturer
Get PDFSupplier selection has become one of the essential effects on the entire electronic supply chain network to gain competitiveness. In the upstream supply chain, companies are able to achieve a high quality and value of products to reduce the potential risks from both internal and external stakeholders by selecting the right suppliers. The case study company produces a nano sim-card connector in which four different types of raw materials are processed into different parts. Currently, the case study company selects each raw material supplier based on its appraisal record. Nevertheless, the appraisal record is measured by the department of procurement. When candidate suppliers are categorized at the same level, the cost becomes the priority criteria to select the supplier, which increases the potential risks of, for example, the components defect rate, a penalty from clients, and a reduction in orders. This paper proposed a Fuzzy analytic hierarchy process (FAHP) model for the selection of raw material suppliers by collecting data from two of the company’s departments (procurement and engineering) and the clients to address qualitative and quantitative elements, uncertainty, and linguistic vagueness based on the company’s scenario in two parts. First, the main and sub-criteria can be weighted using a decision-maker (DM) to identify the level of importance. Second, the FAHP model also dealt with personal preferences and judgement so that the right supplier(s) for each raw material could be selected by collecting and computing the data from the respondents. Then, the sensitivity analysis is applied to observe how the decisions change when the model parameters in the top five sub-criteria change. The proposed model can offer better information and solutions for the DM in the case study company to differentiate the crucial main and sub-criteria and select the suitable raw material suppliers effectively