bluuebunny/crossref_metadata_2025 huggingface dataset:
On boundary stability of inhomogeneous 2 × 2 1-D hyperbolic systems for the C1 norm
Authors: Hayat Amaury
Published: November 2018

We study the exponential stability for the C1 norm of general 2 × 2 1-D quasilinear hyperbolic systems with source terms and boundary controls. When the propagation speeds of the system have the same sign, any nonuniform steady-state can be stabilized using boundary feedbacks that only depend on measurements at the boundaries and we give explicit conditions on the gain of the feedback. In other cases, we exhibit a simple numerical criterion for the existence of basic C1 Lyapunov function, a natural candidate for a Lyapunov function to ensure exponential stability for the C1 norm. We show that, under a simple condition on the source term, the existence of a basic C1 (or Cp, for any p ≥ 1) Lyapunov function is equivalent to the existence of a basic H2 (or Hq, for any q ≥ 2) Lyapunov function, its analogue for the H2 norm. Finally, we apply these results to the nonlinear Saint-Venant equations. We show in particular that in the subcritical regime, when the slope is larger than the friction, the system can always be stabilized in the C1 norm using static boundary feedbacks depending only on measurements at the boundaries, which has a large practical interest in hydraulic and engineering applications.
Thermal Comfort Assessment of an Office Building in Tropical Climate Condition
Authors: Koh Kelly , Al-Kayiem Hussain H. , Kurnia Jundika C.
Published: November 2018

As a lot of people spend their time indoor, indoor thermal comfort will affect the performance of the occupants in terms of health, comfort and productivity. This paper aims to investigate the thermal comfort of an office building constructed using low cost materials in tropical climate condition. That has been achieved by investigating the PMV using the CBE thermal comfort tool in the post-graduate office building in the solar research site in UTP. The experimental measurements have been conducted at two different cases; without ventilation and with air-conditioned in the office building. The thermal comfort of the office building is assessed by using the ASHRAE thermal sensation scale. Results have demonstrated that the office room without ventilation is hot and not suitable for occupants to work at such thermal environment. Thermal comfort of the room with air-conditioning is warm and is slightly better than the room without ventilation as the PMV has been improved by around 60%. However, the acceptable thermal comfort level in the low-cost material office building is yet to be achieved.
The Influence of Temperature on Stability of Aluminum Foam Cell Wall during Foaming Process
Authors: Puspitasari Dewi , Rabie Fatthie Khairullah Hishyam , Ginta Turnad Lenggo , Kurnia Jundika Candra , Mustapha Mazli
Published: November 2018

This study concerns about the influence of foaming temperature which is applied to foaming process of aluminum foam to improve the stability of aluminum foam cell wall. Powder metallurgical method with four major foaming temperatures of 750°C, 800°C, 850°C and 900°C have been selected. Furthermore, the porosity of the foam was determined by ImageJ Analysis Software. Microhardness testing on the cell wall of aluminium foam was conducted according to ASTM E 92 using microhardness tester LM24AT with 200 grams and 15 s for loading time. The universal testing machine was applied to characterize the effect of foaming temperature on compression strength. The aluminum foam was observed in macroscopic and microscopic level using optical microscope (OM). The result revealed that the foaming temperature of 800°C gave the lowest value of porosity, with the highest hardness and compressive strength of 55.29 HV and 1.41 MPa, respectively. In addition, the highest porosity level was acquired by foaming temperature which was set at 900 °C. The lowest hardness value of 38.50 HV was obtained by foaming temperature of 700°C and the minimum compressive strength value of 0.75 MPa was exhibited when the foaming temperature was set at 900°C.
Thermochemical Characterization of Oil Palm Fronds, Coconut Shells, and Wood as A Fuel For Heat and Power Generation
Authors: Inayat Muddasser , Sulaiman Shaharin A. , Naz Muhammad Yasin
Published: November 2018

This study investigated the thermochemical characterization of oil palm fronds (OPF), coconut shells (CS) and wood for their use as a solid fuel for thermal conversion processes. The ultimate analysis, proximate analysis, calorific values, and elemental contents through energy dispersive X-ray spectroscopy of OPF, CS, and wood samples were measured. The results of OPF and CS were compared with wood considered as benchmark solid fuel. Proximate analysis was performed as per ASTM standard procedure in a muffle furnace and used thermos-gravimetric analysis technique. The ultimate analysis was used to determine the weight percentage of carbon, hydrogen, and nitrogen in CHNS analyzer. Elements analysis was done using energy dispersive X-ray spectroscopy. The ultimate analysis results show carbon content was higher in CS as compared to OPF and wood. The hydrogen content was higher in OPF. Proximate analysis results revealed that volatile matter was higher in wood, whereas fixed carbon and higher heating value were found higher in CS while ash content was lower in CS. From EDX results found that the OPF has Al, Si, Cl, and K, while, in wood and CS these elements are absent. The thermochemical characterization results of OPF and CS were comparable with the wood. Therefore, it concluded that OPF and CS have the potential to be used as renewable energy source by using appropriate energy conversion technologies, such as gasification, pyrolysis, and torrefaction.
Vibration Analysis of the Engine Using Biofuel Blends: A Review
Authors: Erdiwansyah  , Sani M.SM. , Mamat Rizalman. , Khoerunnisa Fitri , Rajkumar AR , Razak N.F.D , Sardjono R.E
Published: November 2018

The vibrations and noise of the internal combustion engine may be affected by several factors such as combustion pressure, movement of the piston-crank mechanism, coolant factor flow, engine body, and fuel inlet of the injector. Various ways have been done to reduce vibration and noise in the engine, including fuel. Alternative biofuels can be used in internal combustion engines without having to modify and change parameters on the machine. Several researchers have studied the effects of vibration and noise in the engine using various fuel mixtures. The results from some literature reported that biodiesel blend fuels proved to reduce vibration and noise in engines as compared to pure diesel. Meanwhile, ethanol fuel mixed with gasoline shows significant vibration changes at engine speeds of 1,500 and 2,500 rpm. The review aims to analyse the effects of vibration and noise on engines fueled by fuel mixtures, as well as fuel properties used as a move for future research. Based on the analysis from several kinds of literature, it shows that the use of biodiesel fuel and ethanol-gasoline can reduce vibration and noise.
Experimental Analysis on the Effect of Area of Surface Cooling for a Water-Cooled Photovoltaic
Authors: Basrawi Firdaus , Leon Yeong C. , Ibrahim Thamir K. , Yusof Mohd Hazwan , Razak A.A. , Sulaiman Shaharin Anuar , Yamada Takanobu
Published: November 2018

Water flow for a water-cooled Photovoltaic (PV) may not cover the whole surface area of PV. Thus, the objective of this paper is to experimentally observe the effect of cooling surface area for a water-cooled PV. A water-cooled PV with 30W output was tested when its surface area was 50% and 100% covered with flowing water. This condition was tested at water flow rate of 120 mL/h, and irradiace of 855 W/m2, respectively. It was found that the panel recorded a maximum temperature of 72.10°C when it is uncooled. When it is cooled temperature decreased 22.05% and 51.04% for half and full surface, respectively, and temperature also remained constant approximately at 32oC for full surface. The current remained constant as expected and effect of temperature could be seen in voltage. Voltage increases when temperate decreases, and decreases when temperature increases. As the results, the power outputs for uncooled, half surface, and full surface were 10.38W, 10.66W and 11.08W, respectively. As compared to uncooled, this shows the increment of 6.10% and 13.50% for half surface and full surface, respectively. Thus, it could be concluded that the cooling surface area has substantial effects on the performance of water-cooled PV.
Effects of Diesel-Biodiesel Blends in Diesel Engine Single Cylinder on the Emission Characteristic
Authors: Erdiwansyah  , Mamat R. , Sani M.S.M. , Khoerunnisa Fitri , Sardjono R.E , Ali OM , Ibrahim TK
Published: November 2018

Biodiesel is an alternative fuel that is used in a diesel engine as a substitute for diesel fuel. However, using biodiesel without a modified engine can cause higher NOx emissions. Therefore, to reduce harmful emissions some strategy must be proposed or or a change in the injection is performed. In this study, injection schemes and engine performance injection time, emissions and firing characteristics of biodiesel mixing results in engines were investigated by using GT-POWER simulation. The simulations in this study were conducted on diesel engines to observe the accuracy in experimental results . The engines were tested at speeds of 1100 rpm, 1300 rpm, and 1500 rpm by using a biodiesel-diesel fuel mixture. The simulation results showed that NOx emissions were found to drop below 100 ppm when biodiesel fuel was used for all performed operations. Meanwhile CO emissions were also decreased by 10%-15% when biodiesel fuel was used, and the thermal efficiency level increased by 2% and 3.5% as compared to pure diesel. The ratio of NOx reduction rates of biodiesel and diesel was 11%-14% as compared to 9.5% with pure diesel. Based on the simulation result, it was shown that the accuracy level of simulation data with experiment was 97%. So this result can be the future testing standard and simulation by using GT-POWER could also be used especially for the automotive industry.
Performance of Inductive Coupled Power Transfer Versus the Coil Shape - Investigation using Finite Element Analysis
Authors: Romlie Mohd Fakhizan , Lau Kevin , Zainol Mohd Zaifulrizal , Abdullah Mohd Faris , Kannan Ramani
Published: November 2018

The objective of this paper is to investigate the impact of the spiral coil shape of inductive coupled power transfer on its performance. The coil shapes evaluated are: circular, square and pentagon spiral shapes. The coils are modelled in Ansoft Maxwell software. Simulations are carried out to determine the mutual inductance, coupling coefficient and magnetic flux density. The performance in term of magnetic flux density, mutual inductance and coupling coefficient of the three coils shapes are compared. Of the three shapes, the pentagon is shown to have the best performance in term of its mutual inductance, coupling coefficient and magnetic flux density.
Thermal and Economic Analysis of Gas Turbine Using Inlet Air Cooling System
Authors: Ibrahim Thamir K. , Mohammed Mohammed K. , Awad Omar I. , Mamat Rizalman , Abdolbaqi M. Kh
Published: November 2018

A basic goal of operation management is to successfully complete the life cycle of power systems, with optimum output against minimal input. This document intends calculating both, the performance and the life cycle cost of a gas turbine fitted with an inlet air cooling mechanism. Correspondingly, both a thermodynamic and an economic model are drawn up, to present options towards computing the cooling loads and the life cycle costs. The primary observations indicate that around 120MWh of power is derived from gas turbine power plants incorporating the cooling mechanism, compared to 96.6 MWh for units without the mechanism, while the life cycle cost is lower for units incorporating the cooling process. This indicates benefits in having the mechanism incorporated in the architecture of a gas turbine.
Computational Study of Coal Particle Distribution in Coal Pulverizer: Effect of Air Flow Rate and Coal Particle Flow Rate
Authors: Why Elaine , Alnaimi Firas , Hasini Hasril , Nasif Mohammad
Published: November 2018

Complete combustion of coal fuel in thermal power plant is often achieved, by ensuring output of fine coal particle (< 75μm) is as high as possible. This is due to the fact that same mass of coal particle in smaller sizes, has higher surface exposed to combustion. Hence, the objective of the study is to determine the effect of air flow rate and coal particle flow rate on coal fineness output. Computational fluid dynamics (CFD) modelling and validation with experimental coal fineness test in real plant are made. The optimum range of air flow rate and coal particle flow rate in pulverizer are selected, by considering relevant air/fuel ratio of 1.5 to 2.0 and turbulence intensity.
Comparative Analysis of Clustering Techniques for Movie Recommendation
Authors: Aditya T.S. , Rajaraman Karthik , Monica Subashini M.
Published: November 2018

Movie recommendation is a subject with immense ambiguity. A person might like a movie but not a very similar movie. The present recommending systems focus more on just few parameters such as Director, cast and genre. A lot of Power intensive methods such as Deep Convolutional Neural Network (CNN) has been used which demands the use of Graphics processors that require more energy. We try to accomplish the same task using lesser Energy consuming algorithms such as clustering techniques. In this paper, we try to create a more generalized list of similar movies in order to provide the user with more variety of movies which he/she might like, using clustering algorithms. We will compare how choosing different parameters and number of features affect the cluster's content. Also, compare how different algorithms such as K-mean, Hierarchical, Birch and mean shift clustering algorithms give a varied result and conclude which method will suit for which scenarios of movie recommendations. We also conclude on which algorithm clusters stray data points more efficiently and how different algorithms provide different advantages and disadvantages.
The Effect of Outdoor Temperature on the Performance of a Split-Unit Type Air Conditioner Using R22 Refrigerant
Authors: Yusof Mohd Hazwan , Muslim Sulaiman Mohd , Suhaimi Muhammad Fadhli , Basrawi Mohamad Firdaus
Published: November 2018

To maintain the temperature setup on an air conditioner, the compressor will use more or less energy based on the outdoor temperature. Therefore, there is a need to understand the performance of the air conditioner if the outdoor temperature is varied. In this research, a used small capacity split-unit air conditioner using R-22 refrigerant is used to study the effect of outdoor temperature on the performance of the air conditioner. From the results, it can be understood that lower outdoor temperature requires less work from the compressor. The cooling capacity and coefficient of performance drop as the outdoor temperature increases.
Development of an Adaptive Controller for Gridconnected Power Electronic Converter
Authors: Yahia Khalid , Kannan Ramani , Yahaya Nor Zaihar , Asirvadam Vijanth Sagayan
Published: November 2018

Power electronics converter (PECs) has become an attractive replacement for the conventional inverter in grid-tied photovoltaic (PV) applications. This is due to improved the transient performance and provided better power quality. In this paper, an improved controller and a novel topology for a PEC is proposed. In this paper, an improved controller and a novel topology for a PEC is proposed. The proposed PEC topology is based on the three-level converter and adaptive PI with a fuzzy logic controller (API-FLC). The PEC with the novel controller is designed to achieve constant DC link voltages and sinusoidal current and voltage with near unity power factor when operating in different conditions. In order to evaluate the validity of the proposed PEC, the model was simulated by MATLAB/Simulink Toolbox. The results obtained with the proposed converter gives a better dynamic performance and improved power quality compared to the conventional converter.
The Effect of Knee Flexion Angle on Contact Stress of Total Knee Arthroplasty
Authors: Azam N.M.A. , Daud Rosdi , Mas Ayu H. , Ramli J. , Hassan M.F.B. , Hassan M.F.B. , Shah A. , Adib M.A.H.M.
Published: November 2018

The effect of flexion angle on contact stress of the knee joint still open to the debate since lack of proof shown that flexion angles does effect the contact stress of Total Knee Arthroplasty (TKA). Thus the aim of this study is to investigate the effect of different flexion angle on contact stress of TKA via finite element method. The TKA is simulated using ANSYS Workbench and the applied loads are 2200 N, 3200 N and 2800 N. The Finite element Analysis (FEA) results for maximum stress of current and proposed designed were then compared. For the new proposed design, the maximum stress for 15° is 12.2 MPa, 45° is 23.6 MPa and 60° is 22.5 MPa which is lower than current design. Thus, it can be concluded that the new proposed design better than current design in term of contact stress. While, the different flexion angle do gives an impact on the performance of the TKA.
Numerical Evaluation of Heat Transfer and Entropy Generation of Helical Tubes with Various Cross-sections under Constant Heat Flux Condition
Authors: Kurnia Jundika Candra , Sasmito Agus Pulung
Published: November 2018

The presence of curvature-induced secondary flow in helical pipe which create complex transport phenomena and higher transfer rate has attracted significant attention from both academic and industry. Flow behavior and transport processes in helical tube have been intensively investigated. Nevertheless, most studies were focused on the performance based on first law of thermodynamics with limited studies concerning the performance based on second law of thermodynamics. The objective of this study is to investigate the heat transfer performance of helical tube according to both first and second law. The heat transfer rate and entropy generation of helical tubes with various cross-sections, i.e. circular, ellipse and square, subjected to constant wall heat flux conditions are numerically evaluated by utilizing computational fluid dynamics (CFD) approach. Their performances are compared to those of straight tube with identical cross-section. The results indicate that helical tube provides higher heat transfer at the cost of higher pressure. Moreover, it was found that entropy generation in helical tubes is considerably lower as compared to that in straight tube. Among the studied cross-sections, square has the highest heat transfer albeit having the highest pressure drop and entropy generation for both straight and helical tubes.
Co-gasification of Corn and Coconut Residues in Downdraft Gasifier
Authors: Tamili Norazilah , Chuan Lee Kean , Sulaiman Shaharin A. , Moni Mohamad Nazmi Z. , Inayat Muddasser , Lo Michael Yin Kai
Published: November 2018

Reliance on a single biomass to generate electrical power can cause disruption due to the inconsistencies in the supply of biomass feedstock. Co-gasification of different biomass can mitigate the problem of inconsistence biomass supply. The aim of this study to investigate thermochemical properties of corn residues (CR) and coconut shells (CS) and syngas performance produced from co-gasification of CR and CS. Biomass materials were characterized in order to understand their physical properties in relation to thermochemical conversion. Co-gasification of CR and CS was carried out in externally heated downdraft gasifier at CR:CS ratio of 50:50, 40:60 and 20: 80. CO composition obtained from blended feedstock is higher as compared to the without blended feedstock. The CO2 and CH4 concentration were increased as CS proportion increased in blend. Biomass with higher moisture content plays important role in the H2 production due to the supercritical water gasification. The blending ratio of CR and CS at 20:80 had a positive synergetic effect as evident by increase in the gas composition for CO, CH4 and H2. It is concluded that co-gasification results of CR and CS is practical and can be considered to complement each other.
Mathematical Modelling of High Voltage Gain Converter Using P and O for PV Based Application
Authors: Thiyagu Arunkumari , Indragandhi V. , Kannan Ramani
Published: November 2018

This manuscript proposes a novel single switch converter which attains high voltage gain using P and O algorithm. The proposed converter is multilevel with voltage tripler technique. Here the output voltage gain attained is 11 times than the input source. The voltage ripple attained is less compared to other models. The main advantage of the converter is high efficiency, reduced switch loss, high gain and reduction in ripple. The converter attains efficiency of 97.3% at full load condition. The proposed converter is analysed by both Simulink MATALAB and Hardware prototype.
Solar Thermal Power: Appraisal of Solar Power Towers
Authors: Shatnawi Hashem , Lim Chin Wai , Ismail Firas Basim
Published: November 2018

This study delves into several engineering procedures related to solar power tower plants. These installations come with central receiver system technologies and high-temperature power cycles. Besides a summary emphasizing on the fundamental components of a solar power tower, this paper also forwards a description of three receiver designs. Namely, these are the tubular receiver, the volumetric receiver and the direct absorber receiver. A variety of heat transfer mediums were assessed, while a comprehensive explanation was provided on the elements of external solar cylindrical receivers. This explanation covers tube material, molten salt, tube diameter and heat flux.
Mathematical Modelling and Transient Thermal Analysis of Coupler-Rocker Bearing
Authors: Jamil Abdullah , Baharom Masri B. , Lemma Tamiru Alemu
Published: November 2018

Friction is the resisting force between two bodies having relative motion. These bodies can be solid surfaces, fluid films or elements sliding against each other. There are many devices used to overcome sliding friction which include wheels and bearings. Ball bearings are used in many high speed and high precision machine tools because of their high productivity. A Crank-Rocker four bar mechanism consists of 4 linkages and 4 nodes. These nodes perform complex motions especially the coupler-rocker joint. In order to reduce the friction between these relatively moving links, ball bearings can be introduced. The coupler-rocker bearing oscillates about some axis as well as the raceways have some relative motion. Heat generation rate is not known for bearings performing this type of complex motion. This paper describes the mathematical modelling and thermal analysis of coupler-rocker bearing. Heat generation in the bearing can be estimated using this model. This can be countered by having proper lubrication and speed of bearing.
Wind Velocity Data Interpolation Using Rational Cubic Spline
Authors: Karim Samsul Ariffin Bin Abdul , Suresh Kumar Raju S.
Published: November 2018

Wind velocity data is always having positive value and the minimum value approximately close to zero. The standard cubic spline interpolation (not-a-knot and natural) as well as cubic Hermite polynomial may be produces interpolating curve with negative values on some subintervals. To cater this problem, a new rational cubic spline with three parameters is constructed. This rational spline will be used to preserve the positivity of the wind velocity data. Numerical results shows that the proposed scheme work very well and give visually pleasing interpolating curve on the given domain.
Preliminary Study on Drying of Stingless Bee Pot Pollen Using Novel Fluidized Bed Dryer with Swirling Distributor
Authors: Halim Luqman Abdul , Basrawi Firdaus , Chong Jia Zheng , Oumer Ahmed Nurye , Yudin Ahmmad Shukrie Md , Yusof Mohd Hazwan bin , Sulaiman Shaharin A
Published: November 2018

High moisture content in raw pot pollen increases the activity of microorganisms, thus promotes fermentation and causes rapid deterioration. Hence, the objective of this study is to dry stingless bees pot pollen by a novel fluidized bed dryer. The experimental analysis was conducted based on flowrate, airflow temperature, power consumption and sample mass. It was found that the mass of pot pollen can be reduced by 6.86 % in 30 minutes of drying operation. The temperature rise is also minimal up to average of 31.5°C. This significantly reduced the impact of drying not only to the nutrients, but also the flavour and aroma. Moreover, the total energy consumed is 212.57 Wh, which is considered low. Hence, this preliminary study showed the feasibility of drying pot pollen using a novel fluidized bed dryer.
CFD Analysis of Hybrid Solar Chimney Power Plant
Authors: Aurybi Mohammed A. , Al-Kayiem Hussain H. , Gilani Syed I.U. , Ismaeel Ali A.
Published: November 2018

In this study, a novel approach has been proposed as a solar chimney integrated with an external heat source to extend the system operation during the absence of solar energy. Flue gas channels have been utilized to exchange heat with the air inside the collector of the solar chimney. The hybrid solar chimney has been investigated numerically by ANSYS-Fluent software, using discrete ordinates radiation model. The hybrid system was simulated in 3D, steady-state by solving Navier-Stokes and energy equations. The numerical results have been validated using experimental measurements of a conventional solar chimney. The influence of flue channels on the system performance was predicted and analyzed in hybrid mode. With 0.002 kg/s of flue gas at 100°C injected in flue channels during the daytime; hybrid mode results demonstrated enhancement of 24% and 9 % for velocity and temperature, respectively. The power generation was enhanced by 56%. It has been proved that the proposed technique is able to resolve the set back of night operation problem of the solar chimney plants.
Suitability of base liquid in a nanofluid-laden solar flat-plate collector with emphasize on bioglycol
Authors: Shamshirgaran Seyed Reza , Al-Kayiem Hussain H. , Assadi Morteza K. , Sharma K.V.
Published: November 2018

Ethylene glycol and propylene glycol are commonly used as thermal liquids in solar flat-plate collectors (FPCs). They are utilized as base liquid as well as for improving the stability of nanofluids in FPCs. The objective of the present paper is to introduce a renewable-derived bio glycol for use as base liquid in FPCs. The effect of base ratio (BR) of different glycol products on the performance of a conventional FPC and a nanofluidladen FPC is investigated in this paper to determine its suitability. MATLAB programming was employed for modeling the performance of the FPC operating with copper and cerium oxide nanomaterials. The results show that 20:80 bio glycol/water mixture is capable of enhancing the FPC’s energetic efficiency up to 72.1% which is higher than with either ethylene glycol and propylene glycol. The energy efficiency of a glycol-based nanofluid-filled FPC decreases with the base ratio of all three glycol products. Since bio glycol is a non-toxic and safe product, it can be utilized as a safe and environmentally-friend antifreeze and base liquid in nanofluid-filled FPCs.
Effects of Shell Encapsulation on the Nonlinear Dynamics of a Microbubble Contrast Agent subjected to Acoustic Energy
Authors: Dzaharudin Fatimah , Ali Najihah Mohd , Alias Erny Afiza , Jamaludin Ummu Kulthum
Published: November 2018

The effects of encapsulating a microbubble on the energy in oscillation and acoustic signature is investigated by solving the governing equations of motion. Numerical data obtained by solving these equations is used to explore the effects of shell on the harmonics of the bubble system. By encapsulating the microbubble with a shell, the bubble will be stiffer resulting in lower amplitude oscillations and an increase in the harmonics of the bubble system upon subjected to acoustic energy. This is desirable in triggering vascular permeability for drug/gene control and release in biomedical applications.
Evaluation on Methods in Estimating the Photovoltaic Performances Affected by Module Operation Temperature in Tropical Region
Authors: Chand M.R.R. , Basrawi Firdaus , Aziz Azizuddin Abd , Azran Zafri , Sulaiman Shaharin Anwar , Zulkepli Afzam
Published: November 2018

This research work is intended to evaluate the reliability of commonly utilized empirical correlations of module operation temperature in estimating the photovoltaic performances in tropical region. The Nominal Operation Cell Temperature (NOCT) model, Tropical Field Operation Cell Temperature (tFOCT) model and the experimental back module temperature were selected for evaluation purposes. The models were evaluated by comparing the performance characteristics of a 250W monocrystalline photovoltaic module installed at University Malaysia Pahang. The monocrystalline back module temperature and power output as well as the environmental data including both solar irradiation and ambient temperature were monitored to assist the analysis. Based on the 5 consecutive day experimental data, results indicated that the module operation temperature estimated by tFOCT model had the closest value to the experimental back module temperature. Whereas, the temperature estimated by NOCT model showed the highest deviation up to 25.8% from the experimental back module temperature. However, in terms of estimating the photovoltaic module power output, the NOCT model had the closest value to the experimentally measured power output. The results also indicated that utilizing the back module temperature often mislead the estimation of photovoltaic module power output. In addition, the deviation of estimated power output from NOCT model, tFOCT model and back module operation temperature as compared to the experimental power output were 15.4%, 18.87% and 21.2%, respectively. Thus, the NOCT model demonstrated better estimation of power output as compared to the experimental result than tFOCT model, and back module temperature. However, better estimation method for tropical regions is still needed because three methods evaluated in this study shows deviation of more than 15.4% from the measured power output.
Neutral Earthing Reactance Design in Mitigating Third Harmonic Current at the Generator Neutral
Authors: Rahman H.A. , Shah Riman N.I. , Abdullah M.F. , Sakidin H. , Romlie M.F. , Nor N.M.
Published: November 2018

Third harmonic (TH) current from salient-pole synchronous generator that return to its neutral via cable capacitance or other neutral grounding points in the network can cause the neutral earthing resistor (NER) to experience high temperature. Generator neutral earthing reactance (NERX) can be used to mitigate the TH current flowing in the neutral under normal condition. This paper aims to study the suitable design of NERX to be implemented in Universiti Teknologi PETRONAS (UTP) distribution system to reduce the TH current at the generator neutral. The model of UTP distribution system is developed using MATLAB Simulink in order to simulate the flow of TH current. NERX is then designed and implemented to the system to mitigate the magnitude of TH current. Various values of NERX are applied to the system as the neutral current and fault current are recorded and graphed. The application of 0.175 H NERX increased the TH neutral current in island mode and normal operation to 33.18 %. However, the NERX causes the TH fault current to reduce to 44.33 % under fault. For parallel mode, 78.27 % of TH neutral current and also 42.91 % of TH fault current are reduced under normal operation and fault respectively.
Experimental Investigation of Performance and Emission Characteristics of IDI Diesel Engine Using Homogenized Water in Bio-Diesel Emulsion
Authors: Karim Zainal Ambri Abdul , Khan Mohammed Yahaya
Published: November 2018

Water in diesel emulsion when used as fuel in diesel engine has shown simultaneous reduction in both nitrogen oxides and particulate matters. However, when water in bio-diesel emulsion is used, the effect of simultaneous reduction of nitrogen oxides and particulate reduction is not achieved. The current study aims at investigating the diesel engine performance and exhaust emissions using water in bio-diesel fuel prepared by a homogenizer that produced micro-water particles in the emulsion. A 1.8L indirect injection diesel engine was operated using bio-diesel fuel which contains 95% diesel and 5% palm oil methyl ester, mixed with 5%, 10% and 20% by volume of water. Engine testing was conducted at full load condition with the engine speeds ranges from 1000 to 4000 rpm. Torque, engine speed and fuel consumption were measured along with emissions of NOx, CO, CO2, HC, O2. The results showed small reduction in brake power, 1.4% and 2.1% for WBDE-5 and WBDE-10 respectively, at maximum torque. While, reduction in exhaust gas temperature, CO2 and smoke opacity for all the tested emulsions were exhibited. On the other hand, NOx was found to increase with increase in water contents due to the higher oxygen content in the bio-diesel fuel. WBDE-20 showed the worst efficacy due to having water content of 20% by volume.
Operating Parameter Optimization using DOE Method to Reduce Unburned Carbon of Fly Ash for Tangential Fired Subcritical Coal Fired Power Plant
Authors: Gurusingam Pogganeswaran , Ismail Firas Basim , Sundaram Taneshwaren
Published: November 2018

As electric demand increasing due to rapid economic growth, most developing country are sourcing for cheap fuel and low maintenance power plant which coal fired power plant become the more preferable plant. The cheap and abundant coal resources have played a major factor for coal power plant selection compare to other type of power plant. Although this plant type has low maintenance and operating cost but its emission of by product has a great effect on daily plant operation and environment. The one of the major emission was unburned carbon which by product of incomplete combustion where remaining of coal that unburned exits the furnaces with ash. Presence of higher percentage of unburned carbon indicates the low efficiency of furnace combustion and this directly affects financial status of the power plant operators. This condition causes severe damages on the boiler tube by formation of slagging and clinkering which reduces heat transfer and efficiency of the furnace. Current method proved to be more time consuming and plant operator facing difficulty to reduce unburned carbon in real time. As a solution for this problem, a best parameter was predicted to achieve low percentage of unburned carbon.
A Parametric Study to Investigate Human Injury and Fatality due to Vapor Cloud Explosion
Authors: Niazi Usama Muhammad , Nasif Mohammad Shakir , Muhammad Masdi Bin , Imran Muhammad
Published: November 2018

The processing area of an offshore platform consists of various equipment for handling, separation and transferring of crude oil and natural gas. Consequently, the chances of an accidental release are quite high as compared to other areas. Among the major hazard posed on an offshore platform, Vapor Cloud Explosion (VCE) is the fatal one. Among the various factors that impact the resulting overpressure developed due to VCE: leak rates, wind speeds, and wind directions are the important ones. The current paper investigates the effect of these factors (leak rates, wind speeds and wind directions) on explosion strength on an offshore platform. The release, dispersion and resulting VCE are modelled by utilizing Computational Fluid Dynamics (CFD) software Flame Acceleration Simulator (FLACS). Furthermore, risk estimation for human injury/fatality (risk of eardrum rupture, head impact, and whole-body displacement) has been done considering these factors using probit models. The results showed that these factors (leak rates, wind speeds, and wind directions) have a major impact on resulting explosion strength and consequently, on the risk of human injury/fatality. Risk of head impact is quite high while risk of eardrum rupture and whole-body displacement is low. The current study can be useful in designing effective safety measures to reduce the impact of such accidents.
Centrifugal Pump Performance Characteristics for Domestic Application
Authors: Jilani Aisyah , Razali Akhtar
Published: November 2018

Water pressure problems at home can be quite frustrating in daily life which is comes in different ways of complication. It may take forever for the faucets to fill a bathtub, or a slow spray shower head and longer time taken for the washing machine to run a cycle. The problem can be fixed by installing a pressure booster pump. This research is embarked to study on a centrifugal pump performance with a view to analyse pressure built-up and flowrate in pipe at fixed speed. A simple and inexpensive test rig is developed to resemble water distribution for domestic use; i.e. house application. The method is then experimentally validated to measured and analysed the pump performance such as water pressure, water flowrate, power of pump and pump speed. Since the centrifugal pump are added, the pump is able to boost the water flowrate. However, since the centrifugal pump work at constant speed, the water pressure in pipe is high when the water demand is low. The maximum pressure inside the pipe was 28.24 psi which quite high and exceed the piping standards. Power consumption also remained constant approximately 0.500 kWh when water demand was low which led to energy wastage.
Fundamental Characteristics of Microbubbles in Water and Diesel Fuel
Authors: Erny Afiza , Fatimah Dzharudin , Muhammad Izhar
Published: November 2018

Recently, the usage of oxygenated fuel has emerged as a reliable way to enhance engine performance. Due to this matter, the potential of microbubbles (MB) mixed fuel in improving engine performance is anticipated. Being small in size, MB are characterized by having unique characteristics such as low rising speed and self-pressurization which can contribute to fuel oxygenation. In this study, the fundamental characteristics of MB in diesel and water medium were investigated. The MB are produced by shearing air into the high pressurized fluid. Then the life span as well as the size distribution of the MB in both mediums were observed. MB in water shrink faster compared to MB in diesel despite the differences in size range. As for size distribution, no significant tendency can be seen between both mediums.
Indoor Air Quality Evaluation of Commercial Buildings In Kuantan
Authors: Yahaya Noor Huwaida , Hagos Ftwi Yohaness , Basrawi Mohamad Firdaus
Published: November 2018

This work focuses on indoor air quality evaluation of commercial buildings in Kuantan. Some buildings have been selected to monitor indoor air quality. The research has been carried out only in Kuantan, which focused on hotels and government buildings. Some sample measurements were taken which include air temperature, relative humidity, and air movement, carbon monoxide (CO), carbon dioxide (CO2), ozone (O3), respirable particulate matter (PM 10), formaldehyde and total volatile organic compound (TVOC). In addition, questionnaires were conducted on a number of workers in each building to determine the level of health and illness caused by air in the building where they work. Hence, this study has analyzed the link between the questioner results and the results of indoor air measurements that were carried out. From surveys, it appears there are four buildings that have low air flow, four buildings have a lot of dust and five buildings have a high temperature. In contrast, four buildings have a good indoor air quality.
Thermal and Fluid Dynamic Analysis of Compact Fin-and-Tube Heat Exchangers for Automotive Applications
Authors: Adam A.Y. , Oumer A.N. , Alias Azri , Ishak M. , Mamat R. , Abdul Adam A.
Published: November 2018

Flat tubes heat exchangers are commonly used in many industrial applications as a consequence of the distinctive geometrical characteristics of the flat tube compared with round tube. This paper aims to investigate the flow and heat transfer characteristics of laminar cross-flow forced convection in compact fin-and-flat tube heat exchangers. The experiment was performed to explore the influence of the tube inclination angle on the thermal hydraulic performance of the flat tube heat exchanger. Four flat tubes arranged in two aligned rows having the same longitudinal and transverse pitches have been examined in the range of Reynolds number between 1768.27 and 2259.46. A constant heat flux of 4169.63 W/m2was applied at the inner surface of each flat tube. On the other hand, the numerical simulation is solved by ANSYS FLUENT for a two dimensional model with unstructured mesh and the results are compared against the experimental results. The numerical simulation results indicate that the average Nusselt number increased by 78.24 % for Reynolds number 1768.27. Besides that, for Reynolds number 1964.75 and 2259.46 the Nusselt numbers were increased by 75.89 % and 54.49%, respectively, compared to experimental results. Moreover, the pressure drop is increased 25 % and 83.38 % for both experimental and numerical simulation with respect to three Reynolds number. It was found that, the tube with 30° degree provides the higher heat transfer with Reynolds number 2259.46. This study could assist engineers in decisions regarding the application of compact fin-and-tube heat exchangers in the automotive field.
Design Approach of Grid Coupled Solar Inverter
Authors: Babu Bandla Pavan , Indragandhi V. , RajaSingh R. , Kannan Ramani
Published: November 2018

In novel times, more demands are gained by grid connected solar inverters along with the upgrading of the solar energy generation. In grid connected solar power generation, if there is increase in placing more number of solar inverters it may result in effecting the power quality issues. Solar Grid Tied Inverter system is a electrical power generating system that is coupled to the functioning power grid. This power generating system unit consists of elements like Photovoltaic array, DC to DC converter, DC to AC converter, single phase/three phase converter, and AC Source. The inverter converts DC power generated by the array of photovoltaic cells into AC power and this generated AC power is fed to the connected AC loads. If the amount power generation is exceeding the power demanded, excess AC power is supplied to the grid. With this novel approach we can minimize the use of the AC power from the power grid and also even make a generation to the power grid and this is measured with help of net metering. In this paper designing of 281.6Kw grid tied solar power generation and technical specifications required for them are proposed.
Prediction for CUI in Piping Systems using Fuzzy Logic with Sensitivity Analysis of Corrosion Producing Factors
Authors: Khan Muhammad Mohsin , Mokhtar Ainul Akmar , Hussin Hilmi , Muhammad Masdi
Published: November 2018

Corrosion under insulation (CUI) is a progressive problem for piping systems in oil and gas industries especially in petrochemical and chemical plants due to its catastrophic disasters and consequently its automatic impact on the environment. To ensure CUI problem should not spark sudden surprise in plants, indeterminate factors that contribute to the deterioration of pipes subject to CUI should be recognized and taken care seriously. Operating temperature, type of environment, insulation type, pipe complexity and insulation condition of the pipes are the key factors that cause significant deterioration of pipes due to CUI. As per its varying nature, CUI is difficult to predict as it remains hidden beneath the insulation and gets growth in an ambiguous and abrupt manner. For such an uncertain and critical situation, fuzzy logic is a good choice to be deal with. Thus, in this study, CUI corrosion rate for insulated carbon steel piping systems has been predicted by fuzzy logic using API 581 data. Predicted CUI corrosion rates obtained by the developed fuzzy logic model are committing quite satisfactory results when comparing with API 581 published CUI corrosion rates. At the end of study, sensitivity analysis (SA) of CUI producing factors has also been performed. SA is showing the role of each CUI producing factor in terms of percentage, having participation for the cause of 1 mm/year CUI in pipes. The predicted CUI corrosion rates and SA will help inspection engineers for setting and delivering the risk-based inspection priority for insulated piping systems at their concerned plants.
Investigate the effect of lift-off on eddy current signal for carbon steel plate
Authors: Faraj Moneer A , Samsuri Fahmi , AbdAlla Ahmed N , Rifai Damhuji , Ali Kharudin , Al-Douri Y.
Published: November 2018

In this study, the effect of various factors like lift-off and depth defect on the eddy current signal was investigated. Investigation methods like response surface methodology (RSM) and composed central design (CCD) were employed to establish the relationship between lift-off distance, depth of a defect and the eddy current signal by the two-factor interaction equation, and would provide a reference in further to accurate the depth defect. The regression analysis suggested that eddy current signal was well fitted by the two-factor interaction equation (R2 = 0.9656). The eddy current signal was investigated by varying the levels of these two independent variables, in which all have significant influences on eddy current signal. There would be a change in the amplitude and when lift-off distance is altered, and lift off distance increased, the increase of the amplitude of output signal decrease gradually.
Drying characteristics of red chili in a swirling fluidized bed dryer: An experimental study
Authors: Zulkarnain Mohd Azlan , Rashid Nor Farhanim Md , Yudin Ahmmad Shukrie Md
Published: November 2018

Red chili is an agricultural product that contains high moisture. In this study, the drying process of red chili was conducted by using two methods which are conventional method of drying under the sun and by using swirling fluidized bed dryer. A fluidized bed column of 108 mm in diameter with slotted distributor of 45° inclination angles was used in the experiment. Result of drying by using conventional method showed that for 1kg of sample the drying time was 13 days with 212g weight reduction and the color of the red chili changed from red to dark red. Meanwhile for swirling fluidized bed dryer the time required was 4 days, 200g weight reduction and the color of red chili maintained. Based on the results obtained, the drying of red chili by using swirling fluidized bed dryer is more efficient as compared to drying by using conventional method.