Zamir Zulkefli - Academia.edu (original) (raw)
Papers by Zamir Zulkefli
pertanika journal of science and technology, Mar 3, 2022
Evaluating Coal-Fired Power Plant (CFPP) performance is a complex process involving the determina... more Evaluating Coal-Fired Power Plant (CFPP) performance is a complex process involving the determination of the turbine cycle Heat Rate (TCHR). This study focuses on determining the TCHR by developing a mathematical model. The model, which incorporates economic analysis of the plant, is developed using energy and mass balance relationships of the turbine cycle, validated using plant commissioning data from a 700MWn CFPP located in Perak, Malaysia. Actual plant data from a 700MWn CFPP is utilized to improve the accuracy and increase the confidence of the results of this study. It was found that at the nominal operating load of 729MWg, there is a Heat Rate (HR) deviation of-1,135 kJ/kWh, leading to daily losses of RM240,447 or USD 60,112. Furthermore, it is possible to utilize the developed model at lower loads as the plant is now being used to operate on "cyclic" loads. The daily losses at a lower load of 431MWg are RM125,767 or USD31,442. Thus, the model is able to compare the plant HR at various loads against commissioning data, and economic analysis is able to be carried out effectively. Valuable information for plant operations and performance engineers could be obtained using this model to determine plant HR.
The paper evaluates the hydrostatic bearing circular recess design selection criteria for an expe... more The paper evaluates the hydrostatic bearing circular recess design selection criteria for an experiment analysis for dynamic response characteristic of rotor-bearing system, incorporated with single pocket recess hydrostatic bearing and orifice compensation. Evaluation of the circular recess hydrostatic bearing design parameter was conducted with comparing experimental values, pressure variation externally pressurized fluid in recess for 0.7 bar and 1 bar, magnification factor, frequency ratio, damping ratio and damped vibration criteria. Numerical values of the bearing design parameter for damping coefficient (Cb) were compared with the experiment damping coefficient (Cc). The hydrostatic bearing of circular recess damping coefficient prediction gives expectable argument less than 5 % variation accuracy with experiment damping coefficient (Cc)
This is a collection of selected, peer reviewed papers from the International Conference on Advan... more This is a collection of selected, peer reviewed papers from the International Conference on Advances in Mechanical and Manufacturing Engineering (ICAM2E 2013), November 25-28, 2013, Kuala Lumpur, Malaysia. The 131 papers are grouped as follows: Chapter 1: Vehicles Engineering, Chapter 2: Sound and Vibration, Chapter 3: Structural Health Monitoring and Detection, Chapter 4: Applied Thermodynamics and Fluid Engineering, Chapter 5: Applied Materials Science, Chapter 6: Technologies of Materials Processing, Chapter 7: Intelligent Manufacturing, and, Chapter 8: Industrial Engineering.
Many measurement schemes have been developed to study the resonant characteristics of a bubble ne... more Many measurement schemes have been developed to study the resonant characteristics of a bubble near a surface. The desire is to be able to measure the free field characteristics of such a bubble. For experimental investigations, a trade off must be made between the size of the apparatus and the free field measurement. Thus there is a need to study the effect of surface interference on the resonant characteristics of a bubble. Additionally, recent works have shown that Xanthan gel is a suitable alternative to sea water when studying linear bubble dynamics. The use of Xanthan gel allows for a bubble to be freely suspended, doing away with the need to mechanically hold the bubble in place. An experiment to study the resonance frequency of an acoustically driven, freely suspended bubble near a surface in Xanthan gel is described. The resonance frequency of the bubble was generally found to not be effected by surface interference for a bubble placed more than 25 bubble radii away from a ...
This paper presents an experimental investigation of an acoustic barrier composed out of an acous... more This paper presents an experimental investigation of an acoustic barrier composed out of an acousticmetamaterial unit cell. The design of the unit cell consists of a square prism, acting as a resonator,within a hexagonal recess manufactured out of a single material. Two materials were used tomanufacture the unit cell: PolyMide Polycarbonate and Polylite Polylactic Acid. The acousticperformance of the unit cell was quantified for both materials using the acoustic absorptioncoefficient and acoustic transmission loss values for frequencies between 100 Hz and 5,000Hz. Theexperimental results indicate that the design reduced the peak absorption coefficient for bothmaterials while also introducing two additional peaks at around 1,500 Hz and at 4,000 Hz. Changesto the absorption coefficient values were observed for frequencies above 1,000 Hz while minimalchanges were observed for frequencies below 1,000 Hz. These results indicate that the proposeddesign, is able to widen the effective freq...
Jurnal Teknologi
Assessing a glove for its ability to reduce vibration transmitted to the hand can be improved if ... more Assessing a glove for its ability to reduce vibration transmitted to the hand can be improved if the transmissibility of the glove to the hand can be predicted. This study proposes a simple lumped parameter model of the hand and the glove for predicting the transmissibility of a glove to the hand. The model of the hand consists of three main body segments: the palm, the fingers, and the palm tissues, connected via translational and rotational springs and dampers. The glove material was represented by translational spring and damper. The results showed that the glove transmissibility predicted using the model overestimated the glove transmissibility measured experimentally at frequencies greater than 62 Hz, implying that a simple three degree-of-freedom model of the hand and the glove may not be able to provide a reasonable prediction of glove transmissibility.
Defence Science Journal, Mar 25, 2010
The paper discusses the computation of finite element modelling (FEM) of a thick welded joint as ... more The paper discusses the computation of finite element modelling (FEM) of a thick welded joint as a high load transfer joint. The FEM utilises MSC PATRAN/NASTRAN software programs to predict and simulate the critical area of a welded joint. The elasticity limit for the specimen was determined and stress distribution was achieved in the joint to indicate critical parts of a welded T-joint and predict the critical locations for crack initiation in this kind of joint. Simulation and experimental results show good in agreement and the ...
Engineering Solid Mechanics
International Journal of Advanced Mechatronic Systems
49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, 2013
Journal of Vibration and Acoustics, 2015
A proposed solution to reducing gear mesh-frequency vibrations in a gear-set involves the utiliza... more A proposed solution to reducing gear mesh-frequency vibrations in a gear-set involves the utilization of hydrostatic bearings placed in series, load wise, with the main support bearing. The hydrostatic bearings are expected to utilize its low pass filtering effect of the vibrational energies to prevent its transmission from the shaft to the gear housing where it would be emitted as noise. The present investigation examines the frequency response of a single-recess circular hydrostatic bearing under applied sinusoidal loads. The results show that as the driving frequency increases, the filtering effect of the hydrostatic bearing increases. The exhibited behavior is similar to the behavior of a low pass filter: negligible filtering effect at low frequencies, the filtering effect increasing from 0% to 90% over the midfrequencies range and the filtering effect remaining at the maximum value as the frequencies of the applied signals continue to increase. This observed behavior is expecte...
SAE Technical Paper Series, 2014
Applied Mechanics and Materials, 2014
Vibration based technique have so far been focused on the identification of structural damage. Ho... more Vibration based technique have so far been focused on the identification of structural damage. However, not many studies have been conducted on the corrosion identification on pipes. The objective of this paper is to identify corrosion on pipes from vibration measurements. A hollow pipe, 500 mm in length with 63.5 mm in diameter was subjected to impact loading using an impact hammer to identify the natural frequency of the tube in two conditions i) without any corrosion and ii) with an induced localized 40 mm by 40 mm corrosion at the middle of the pipe. The shift of natural frequencies of the structures under free boundary conditions was examined for each node of excitation. The results showed that there is a shift in natural frequency of the pipe, between 3 and 4 Hz near to the corrosion area. It can suggested that that the impact vibration is capable of identifying of localized corrosion on a hollow tube.
Applied Mechanics and Materials, 2014
This study presents the assessment of the quality of speech intelligibility of two Malaysian mosq... more This study presents the assessment of the quality of speech intelligibility of two Malaysian mosques and the results are used to develop a set of general acoustical guidelines to be used in the design of a mosque. Two mosques were selected for the research: Masjid UPM and the Masjid Jamek. The objective of the research is to enable the comparison of the acoustics and speech intelligibility between the mosques as function of the size, volume, occupancy and other parameters of the main prayer hall on the acoustic and speech intelligibility of the respective mosques. The reverberation time (RT60), speech level (SL), background noise (BN), signal-to-noise ratio (S/N ratio) were determined and are used to develop the speech transmission index (STI) and rapid transmission index (RASTI) prediction models for both mosques. It was observed from the results that the RT60, STI and RASTI values shows better performance over number of occupancy for both mosques. Furthermore, the BN and SL result...
49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, 2013
pertanika journal of science and technology, Mar 3, 2022
Evaluating Coal-Fired Power Plant (CFPP) performance is a complex process involving the determina... more Evaluating Coal-Fired Power Plant (CFPP) performance is a complex process involving the determination of the turbine cycle Heat Rate (TCHR). This study focuses on determining the TCHR by developing a mathematical model. The model, which incorporates economic analysis of the plant, is developed using energy and mass balance relationships of the turbine cycle, validated using plant commissioning data from a 700MWn CFPP located in Perak, Malaysia. Actual plant data from a 700MWn CFPP is utilized to improve the accuracy and increase the confidence of the results of this study. It was found that at the nominal operating load of 729MWg, there is a Heat Rate (HR) deviation of-1,135 kJ/kWh, leading to daily losses of RM240,447 or USD 60,112. Furthermore, it is possible to utilize the developed model at lower loads as the plant is now being used to operate on "cyclic" loads. The daily losses at a lower load of 431MWg are RM125,767 or USD31,442. Thus, the model is able to compare the plant HR at various loads against commissioning data, and economic analysis is able to be carried out effectively. Valuable information for plant operations and performance engineers could be obtained using this model to determine plant HR.
The paper evaluates the hydrostatic bearing circular recess design selection criteria for an expe... more The paper evaluates the hydrostatic bearing circular recess design selection criteria for an experiment analysis for dynamic response characteristic of rotor-bearing system, incorporated with single pocket recess hydrostatic bearing and orifice compensation. Evaluation of the circular recess hydrostatic bearing design parameter was conducted with comparing experimental values, pressure variation externally pressurized fluid in recess for 0.7 bar and 1 bar, magnification factor, frequency ratio, damping ratio and damped vibration criteria. Numerical values of the bearing design parameter for damping coefficient (Cb) were compared with the experiment damping coefficient (Cc). The hydrostatic bearing of circular recess damping coefficient prediction gives expectable argument less than 5 % variation accuracy with experiment damping coefficient (Cc)
This is a collection of selected, peer reviewed papers from the International Conference on Advan... more This is a collection of selected, peer reviewed papers from the International Conference on Advances in Mechanical and Manufacturing Engineering (ICAM2E 2013), November 25-28, 2013, Kuala Lumpur, Malaysia. The 131 papers are grouped as follows: Chapter 1: Vehicles Engineering, Chapter 2: Sound and Vibration, Chapter 3: Structural Health Monitoring and Detection, Chapter 4: Applied Thermodynamics and Fluid Engineering, Chapter 5: Applied Materials Science, Chapter 6: Technologies of Materials Processing, Chapter 7: Intelligent Manufacturing, and, Chapter 8: Industrial Engineering.
Many measurement schemes have been developed to study the resonant characteristics of a bubble ne... more Many measurement schemes have been developed to study the resonant characteristics of a bubble near a surface. The desire is to be able to measure the free field characteristics of such a bubble. For experimental investigations, a trade off must be made between the size of the apparatus and the free field measurement. Thus there is a need to study the effect of surface interference on the resonant characteristics of a bubble. Additionally, recent works have shown that Xanthan gel is a suitable alternative to sea water when studying linear bubble dynamics. The use of Xanthan gel allows for a bubble to be freely suspended, doing away with the need to mechanically hold the bubble in place. An experiment to study the resonance frequency of an acoustically driven, freely suspended bubble near a surface in Xanthan gel is described. The resonance frequency of the bubble was generally found to not be effected by surface interference for a bubble placed more than 25 bubble radii away from a ...
This paper presents an experimental investigation of an acoustic barrier composed out of an acous... more This paper presents an experimental investigation of an acoustic barrier composed out of an acousticmetamaterial unit cell. The design of the unit cell consists of a square prism, acting as a resonator,within a hexagonal recess manufactured out of a single material. Two materials were used tomanufacture the unit cell: PolyMide Polycarbonate and Polylite Polylactic Acid. The acousticperformance of the unit cell was quantified for both materials using the acoustic absorptioncoefficient and acoustic transmission loss values for frequencies between 100 Hz and 5,000Hz. Theexperimental results indicate that the design reduced the peak absorption coefficient for bothmaterials while also introducing two additional peaks at around 1,500 Hz and at 4,000 Hz. Changesto the absorption coefficient values were observed for frequencies above 1,000 Hz while minimalchanges were observed for frequencies below 1,000 Hz. These results indicate that the proposeddesign, is able to widen the effective freq...
Jurnal Teknologi
Assessing a glove for its ability to reduce vibration transmitted to the hand can be improved if ... more Assessing a glove for its ability to reduce vibration transmitted to the hand can be improved if the transmissibility of the glove to the hand can be predicted. This study proposes a simple lumped parameter model of the hand and the glove for predicting the transmissibility of a glove to the hand. The model of the hand consists of three main body segments: the palm, the fingers, and the palm tissues, connected via translational and rotational springs and dampers. The glove material was represented by translational spring and damper. The results showed that the glove transmissibility predicted using the model overestimated the glove transmissibility measured experimentally at frequencies greater than 62 Hz, implying that a simple three degree-of-freedom model of the hand and the glove may not be able to provide a reasonable prediction of glove transmissibility.
Defence Science Journal, Mar 25, 2010
The paper discusses the computation of finite element modelling (FEM) of a thick welded joint as ... more The paper discusses the computation of finite element modelling (FEM) of a thick welded joint as a high load transfer joint. The FEM utilises MSC PATRAN/NASTRAN software programs to predict and simulate the critical area of a welded joint. The elasticity limit for the specimen was determined and stress distribution was achieved in the joint to indicate critical parts of a welded T-joint and predict the critical locations for crack initiation in this kind of joint. Simulation and experimental results show good in agreement and the ...
Engineering Solid Mechanics
International Journal of Advanced Mechatronic Systems
49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, 2013
Journal of Vibration and Acoustics, 2015
A proposed solution to reducing gear mesh-frequency vibrations in a gear-set involves the utiliza... more A proposed solution to reducing gear mesh-frequency vibrations in a gear-set involves the utilization of hydrostatic bearings placed in series, load wise, with the main support bearing. The hydrostatic bearings are expected to utilize its low pass filtering effect of the vibrational energies to prevent its transmission from the shaft to the gear housing where it would be emitted as noise. The present investigation examines the frequency response of a single-recess circular hydrostatic bearing under applied sinusoidal loads. The results show that as the driving frequency increases, the filtering effect of the hydrostatic bearing increases. The exhibited behavior is similar to the behavior of a low pass filter: negligible filtering effect at low frequencies, the filtering effect increasing from 0% to 90% over the midfrequencies range and the filtering effect remaining at the maximum value as the frequencies of the applied signals continue to increase. This observed behavior is expecte...
SAE Technical Paper Series, 2014
Applied Mechanics and Materials, 2014
Vibration based technique have so far been focused on the identification of structural damage. Ho... more Vibration based technique have so far been focused on the identification of structural damage. However, not many studies have been conducted on the corrosion identification on pipes. The objective of this paper is to identify corrosion on pipes from vibration measurements. A hollow pipe, 500 mm in length with 63.5 mm in diameter was subjected to impact loading using an impact hammer to identify the natural frequency of the tube in two conditions i) without any corrosion and ii) with an induced localized 40 mm by 40 mm corrosion at the middle of the pipe. The shift of natural frequencies of the structures under free boundary conditions was examined for each node of excitation. The results showed that there is a shift in natural frequency of the pipe, between 3 and 4 Hz near to the corrosion area. It can suggested that that the impact vibration is capable of identifying of localized corrosion on a hollow tube.
Applied Mechanics and Materials, 2014
This study presents the assessment of the quality of speech intelligibility of two Malaysian mosq... more This study presents the assessment of the quality of speech intelligibility of two Malaysian mosques and the results are used to develop a set of general acoustical guidelines to be used in the design of a mosque. Two mosques were selected for the research: Masjid UPM and the Masjid Jamek. The objective of the research is to enable the comparison of the acoustics and speech intelligibility between the mosques as function of the size, volume, occupancy and other parameters of the main prayer hall on the acoustic and speech intelligibility of the respective mosques. The reverberation time (RT60), speech level (SL), background noise (BN), signal-to-noise ratio (S/N ratio) were determined and are used to develop the speech transmission index (STI) and rapid transmission index (RASTI) prediction models for both mosques. It was observed from the results that the RT60, STI and RASTI values shows better performance over number of occupancy for both mosques. Furthermore, the BN and SL result...
49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, 2013