Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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A Comparison between the Post- and Pre-dispersive Near Infrared Spectroscopy in Non-Destructive Brix Prediction Using Artificial Neural Network
Get PDFEven though near infrared (NIR) spectroscopy have been implemented in determining the Brix of pineapples, no traceable study compares the effects of different acquisition designs. Thus, this study aims to evaluate the prediction performance of both pre- and post-dispersive NIR sensing devices in non-destructive Brix prediction using artificial neural network (ANN). The pre-dispersive device has five narrowband light emitting diodes (LEDs) with different wavelengths and a photodiode detector, whereas the post-dispersive device has a bifurcated fiber optic, a broadband LED, and a spectral sensor. First, the NIR diffuse reflectance was non-destructively collected using both NIR devices. Then, the collected diffuse reflectance was calibrated with the white and dark references, and then pre-processed using normalization and standard normal variate methods. After that, ANNs were built for both devices using the pre-processed data. Results show both devices are suitable for sample screening application with range error ratio (RER) of more than seven. Nevertheless, the ANN that trained using the post-dispersive device outperformed that trained using the pre-dispersive device with an 8.1% improvement of correlation coefficient of prediction (i.e. from 0.6853 to 0.7408), and a 5.7% improvement of root mean square error of prediction (i.e. from 1.3918 to 1.313°Brix)
Antibacterial Effects of Copper Microparticles/Copper Nanoparticles/Copper(II) Oxide Nanoparticles and Copper Microparticles/Copper Nanoparticles/Copper(I) Oxide Nanoparticles from Ultrasono-Electrochemical with Hydrothermal Assisted Synthesis Method
Get PDFCopper is a versatile metal with various properties, including antibacterial effects. There are many methods to produce nano-enhanced copper. In this study, we explore the ultrasono-electrochemical with hydrothermal assisted method to produce copper/copper oxides nanoparticles by using ultrasono-electrochemical process to produce copper micro/nano particles, ultrasonication process to produce copper oxide nanoparticles and hydrothermal process to produce cuprous oxide nanoparticles. Antibacterial properties of the produced particles were tested by conventional bacterial identification test and conventional total viable count test using 4 standard bacteria: Escherichia coli, Salmonella enteritidis, Staphylococcus epidermidis and Staphylococcus aureus. The results show that ultrasono-electrochemical method can produce high purity copper micro and nano particles with zero oxidation with the average size of 575 and 118 nm, ultrasonication process can produce copper oxide nanoparticles on copper microparticle and nanoparticle surfaces with the average size of 56 nm, and hydrothermal process can produce cuprous oxide nanoparticles on copper microparticle and nanoparticle surfaces with the average size of 50 nm. All particles with concentration of 0.5 mmol/ml are highly effective as antibacterial agents against Staphylococcus epidermidis. Copper oxide nanoparticles are effective against Salmonella enteritidis, Staphylococcus epidermidis and Staphylococcus aureus, while cuprous oxide nanoparticles are highly effective against all 4 species of bacteria, at over 99.17%
Propagation of Own Non- Axisymmetric Waves in Viscoelastic Three-Layered Cylindrical Shells
Get PDFThe relevance of the study of the dynamic movements of structures consisting of a thin-walled shell and a viscoelastic cylindrical cavity mounted on it is due to their widespread application in modern technology. The mechanical system under consideration consists of two concentric cylindrical shells with a viscoelastic filler (or cylinder) between the shells. The filler and shell can be firmly attached to the outer and inner shells along the entire cylindrical surface. The basic equations of small oscillations of the shell theory and the three-dimensional viscoelasticity theory are used to describe the oscillations of the “shell-filler-shell” system with the exact satisfaction of the contact boundary. The main purpose of the work is to develop a method and algorithm for calculating the problems of propagation and absorption of natural waves in a mechanical "shell-filler-shell" mechanical system. A calculation method based on Müller, Gauss and orthogonal running methods was developed. The Kirchhoff-Love and Tymoshenko hypotheses are used for the cylindrical shell. For dissipative homogeneous and non-homogeneous mechanical systems, the variation of the real and imaginary parts of the complex phase velocity from different system parameters was studied. For sufficiently long waves, Kirchhoff-Love and Tymoshenko hypothesized that the phase velocities of the first form were found to be well matched. It was also found that it is possible to use shell equations for shortwave, taking into account the compression of the filler. It was found that the increase in filler thickness was particularly significant for the relatively small thickness of the filler
An Efficient Algorithm in Computing Optimal Data Concentrator Unit Location in IEEE 802.15.4g AMI Networks
Get PDFWith a view to achieve several goals in the smart grid (SG) such as making the production and delivery of electricity more cost-effective as well as providing consumers with available information which assists them in controlling their cost, the advanced metering infrastructure (AMI) system has been playing a major role to realize such goals. The AMI network, as an essential infrastructure, typically creates a two-way communication network between electricity consumers and the electric service provider for collecting of the big data generated from consumer’s smart meters (SM). Specifically, there is a crucial element called a data concentrator unit (DCU) employed to collect the boundless data from smart meters before disseminating to meter data management system (MDMS) in the AMI systems. Hence, the location of DCU has significantly impacted the quality of service (QoS) of AMI network, in particular the average throughput and delay. This work aims at developing an efficient algorithm in determining the minimum number of DCUs and computing their optimum locations in which smart meters can communicate through good quality wireless links in the AMI network by employing the IEEE 802.15.4g with unslotted CSMA/CA channel access mechanism. Firstly, the optimization algorithm computes the DCU location based on a minimum hop count metric. Nevertheless, it is possible that multiple positions achieving the minimum hop count may be found; therefore, the additional performance metric, i.e. the average throughput and delay, will be utilized to select the ultimately optimal location. In this paper, the maximum throughput with the acceptable averaged delay constraint is proposed by considering the behavior of the AMI meters, which is almost stationary in the AMI network. In our experiment, the algorithm is demonstrated in different scenarios with different densities of SM, including urban, suburban, and rural areas. The simulation results illustrate that the smart meter density and the environment have substantially impacted on a decision for DCU location, and the proposed methodology is significantly effective. Furthermore, the QoS in urban area, i.e. a highly populated area for SM, of the AMI network is better than those in the suburban and rural areas, where the SM density is quite sparse, because multiple available hops and routes created by neighboring meters in the dense area can help improve the average throughput and delay with the minimum hop count
Correlation between Destructive and Non-destructive Characteristics of Pumice and Scoria Lightweight Concretes
Get PDFThis study presents empirical correlations between destructive and non-destructive characteristics of structural lightweight concrete utilizing Medium-K basaltic andesitic pumice and scoria collected from Kelud Volcano, Indonesia. The non-destructive characteristics comprised the rebound number (N) obtained by Schmidt's Hammer test and the pulse velocity (V) obtained by the Ultrasonic Pulse Velocity test. The destructive characteristics were the compressive strength and modulus of elasticity from compressive test, while the tensile strength included splitting tensile strength as well as modulus of rupture from splitting tensile and bending tests. The correlations were determined using simple regression analysis which included linear, quadratic, power and exponential equations. Furthermore, the SonReb method, i.e. multiple regression analysis with linier and power forms of combination of rebound number and pulse velocity, was proposed for comparison. For pumice and scoria lightweight concrete, the simple regression results showed that all destructive characteristics were expressed by the power equation to the rebound number as well as the pulse velocity. This was indicated by coefficients of determination R2 which were the largest compared to the other three equations. However, the results of SonReb method with power form, indicated that the coefficients of determination R2 were greater than the individual regression results so that their formulas provided more reliable results
Mechanical Enhancement of Biodegradable Poly(Butylene Succinate) by Biobased Polyamide11
Get PDFBiodegradable poly(butylene succinate) (PBS) was melt blended with biobased polyamide11, which an epoxy-based chain extender, Joncryl ADR-4300, was added to improve the blend compatibility. Mechanical properties of the blends were evaluated by tensile and impact testing. The blends were characterized by Fourier transform infrared spectroscopy, Differential scanning calorimetry and Thermogravimetric analysis. Morphology was investigated by Scanning electron microscopy. It was found that morphology of the immiscible blends with polyamide11 less than 50 wt% was a sea-island structure. Adding the chain extender confirmed better chemical compatibility in the blends evident by smaller dispersed domain sizes and less pullout. The blends with higher polyamide11 content increased Young’s modulus following the rule of mixture, however, the rigidity was reduced when adding the chain extender. It was interesting to observe that impact strength of the blends with polyamide11 content higher than 30 wt% was enhanced significantly with the presence of chain extender, although tensile strength and elongation at break were reduced. The crystallization temperature of PBS increased with higher polyamide11 content due to the nucleation effect, although the degree of crystallinity was in the same range. The thermal degradation temperature of the blend was shifted to higher temperature confirming the chain extension reaction occurred
Comparative Study of Tensile Strength Ratio of Asphalt Concrete Mixed with AC 60-70 and Polymer Modified Asphalt
Get PDFIn Thailand, the temperature can reach 44.6 ºC with the lowest temperature of -1.4 ºC recorded in northeastern Thailand. When the air temperature changes, the state temperature of asphalt concrete also changes. To ensure a longer usage life of the surface of asphalt concrete and better durability of the asphalt concrete surface in the range of Thai environmental conditions, this research used the tensile strength ratio method to compare the damage caused by moisture. Samples (5 % and 7 % air voids of the volume of the asphalt concrete) were compared for a control group and a conditioned group, which simulated field behavior occurring in Thailand. It was discovered that the resistance to damage caused by moisture depended on the size of the mixed aggregate material and the amount of asphalt cement present in the mixture. The sample containing mixed sizes according to the lower limit had a higher tensile strength than the mixed sizes according to the upper limit and the air voids of asphalt concrete were inversely proportional to its resistance to moisture damage. As the air void volume increased, the tensile strength ratio decreased
Hybrid Genetic Algorithm for Multi-Period Vehicle Routing Problem with Mixed Pickup and Delivery with Time Window, Heterogeneous Fleet, Duration Time and Rest Area
Get PDFMost logistics industries are improving their technology and innovation in competitive markets in order to serve the various needs of customers more efficiently. However, logistics management costs are one of the factors that entrepreneurs inevitably need to reduce, so that goods and services are distributed to a number of customers in different locations effectively and efficiently. In this research, we consider the multi-period vehicle routing problem with mixed pickup and delivery with time windows, heterogeneous fleet, duration time and rest area (MVRPMPDDR). In the special case that occurs in this research, it is the rest area for resting the vehicle after working long hours of the day during transportation over multiple periods, for which with confidence no research has studied previously. We present a mixed integer linear programming model to give an optimal solution, and a meta-heuristic approach using a hybrid genetic algorithm with variable neighborhood search algorithm (GAVNS) has been developed to solve large-sized problems. The objective is to maximize profits obtained from revenue after deducting fuel cost, the cost of using a vehicle, driver wage cost, penalty cost and overtime cost. We prepared two algorithms, including a genetic algorithm (GA) and variable neighborhood search algorithm (VNS), to compare the performance of our proposed algorithm. The VNS is specially applied instead of the mutation operator in GA, because it can reduce duplicate solutions of the algorithms that increase the difficulty and are time-consuming. The numerical results show the hybrid genetic algorithm with variable neighborhood search algorithm outperforms all other proposed algorithms. This demonstrates that the proposed meta-heuristic is efficient, with reasonable computational time, and is useful not only for increasing profits, but also for efficient management of the outbound transportation logistics system
Fibre-Reinforced Polymer Made from Plastic Straw for Concrete Confinement: An Alternative Method of Managing Plastic Waste from the COVID-19 Pandemic
Get PDFPlastic pollution is one of the most significant environmental issues worldwide. During Covid-19 pandemic, single-use plastic containers have been overused due to a lock-down policy. This led to remarkable increase in municipal plastic wastes. An alternative method to manipulate plastic wastes is to recycle them as construction and building materials. The research introduces an idea of using plastic straw to produce fibre-reinforced polymer composite as a strengthening material to confine concrete. The plastic straw fibre-reinforced polymer composite coupons were tested to obtain their tensile strength, ultimate strain, and elastic modulus. A series of compression tests were conducted on plastic straw fibre-reinforced polymer composite confined concrete to investigate the improved strength and ductility performance. The results show that the mechanical properties of plastic straw fibre-reinforced polymer composite are acceptable for concrete strengthening purpose. More importantly, use of plastic straw fibre-reinforced polymer composite is rewarded by its environmental solution for reduction of plastic wastes in household
Biomechanical Performance between Single and Double Lag Screw Trochanteric Gamma Nail used to Stabilize Femoral Neck Fracture: A Finite Element Study
Get PDFThis study was conducted to compare a biomechanical performance between trochanteric gamma nail with single lag screw and double lag screw in the treatment of femoral neck fracture and femoral neck fracture without lesser trochanter. A 3D model of Thai femur was reconstructed from computed tomography spiral scanner whereas a trochanteric gamma nail was reconstructed with the data obtained from 3D laser scanner. A virtual insertion of the nail and femur was done by computer aided design (CAD) software before imported to finite element analysis. The FE models were analysed in the early stage of fracture. Von Mises stress of implant and elastic strain of fracture were observed for each cases. The results showed that a double lag screw provided a better biomechanical performance in femoral neck fracture, especially in femoral neck fracture without lesser trochanter. According to the results, a double lag screw had a lower von Mises stress value on the implant compared to a single lag screw. The elastic strain showed a low value in all double lag screw cases, indicated that a double lag screw produced higher fracture stability