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Yatim Hanim Mohd,Mohd-Ghazali Normah,Mohamad Maziah,Pamitran Agus Sunjarianto,Novianto Sentot 대한설비공학회 2023 International Journal of Air-Conditioning and Refr Vol.31 No.1
The complex behavior of two-phase flow particularly in microchannels can be unpredictable. Experimental measurements are near impossible because of the unavailable compatible assessment equipment. Meanwhile, repeated experiments for reliability of outcomes are costly and involved much time and effort. Environmentally friendly propane is currently being considered as a replacement for hazardous coolants in available refrigeration and air-conditioning systems. This paper reports a system identification (SI) analysis of the collected experimental data of two-phase flow of refrigerant R290 in a microchannel test rig. An ARX model was chosen as the dynamic model, and the modeling of the input–output data was done using a new methodology based on particle swarm optimization (PSO) technique. Measured temperature difference across the microchannel test section and the mass flow rate were the input and output, respectively. The performance of the particle swarm optimization with discoverer (PSOd) was investigated and compared to the original PSO technique. The model was then validated by mean-squared error ( MSE ). Results demonstrate the advantages of discoverer in PSOd over its standard counterpart with a smaller MSE of 6.2629 × 10 −11 and a faster convergence. The SI allows a better prediction of the mass flow rate before any further experiments to obtain the heat transfer coefficient are done. The model provides better management of design of experiments that involve the complex two-phase flow in a microchannel, consequently saving experimental time and cost.
Comparative Assessment for Two Wheels Inverted Pendulum Mobile Robot Using Robust Control
N. M. Abdul Ghani,N. I. Mat Yatim,N. A. Azmi 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10
Over the last decade, numbers of researcher has been increased in the two-wheeled inverted pendulum mobile robots or commonly known as balancing robot. This paper presents the linear modeling of two wheels inverted pendulum mobile robot and the robustness of sliding mode control. Linear modeling plant was obtained from the simplified nonlinear plant that was based on state-space approach. The dynamic model of the system has been established to design and analyze the control system, dynamic of the motors, chassis and wheels of balancing robot. Simulation on MATLAB/SIMULINK application is performed and to determine the performance and reliability of the Sliding Mode Controller.
Jidin, Auzani,Idris, Nik Rumzi Nik,Yatim, Abdul Halim Mohd,Sutikno, Tole,Elbuluk, Malik E. The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.2
Direct torque control(DTC) of induction machines is known to offer fast instantaneous torque and flux control with a simple control structure. However, this scheme has two major disadvantageous, namely, a variable inverter switching frequency and a high torque ripple. These problems occur due to the use of hysteresis comparators in conventional DTC schemes, particularly in controlling the output torque. This paper reviews the utilization of constant frequency torque controllers (CFTC) in DTC to solve these problems while retaining the simple control structure of DTC. Some extensions of the work in utilizing a CFTC will be carried out in this paper which can further reduce the torque ripple. This is particularly useful for a system which has a limited/low sampling frequency. The feasibility of a CFTC with an extended carrier frequency in minimizing the torque ripple is verified through experimental results.
A Hybrid DTC-DSC Drive for High Performance Induction Motor Control
Jidin, Auzani,Idris, Nik Rumzi Nik,Yatim, Abdul Halim Mohamed,Sutikno, Tole,Elbuluk, Malik E. The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.5
This paper describes a hybrid induction motor drive system incorporating DTC-hysteresis and Direct Self Control (DSC) schemes to achieve excellent dynamic performance. The control scheme is switched from a circular to a hexagonal flux locus whenever a dynamic condition is encountered. On the other hand, when the motor operates under steady state conditions, a circular flux locus is used. Without major modifications to the simple structure of a basic DTC, hexagonal flux locus operation is established by modifying the flux error status, before it is fed to the look-up table. The feasibility of the proposed hybrid scheme to achieve excellent control performance is verified by experimental results.
Hysteretic characteristics of steel plate shear walls: Effects of openings
Mustafa M. Ali,S.A. Osman,M.Y.M. Yatim,Al Zand A.W. 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.76 No.6
Openings in steel plate shear walls (SPSWs) are usually used for decorative designs, crossing locations of multiple utilities and/or structural objectives. However, earlier studies showed that generating an opening in an SPSW has a negative effect on the cyclic performance of the SPSW. Therefore, this study proposes tripling or doubling the steel-sheet-plate (SSP) layer and stiffening the opening of the SPSW to provide a solution to undesirable opening effects, improve the SPSW performance and provide the infill option of potential strengthening measures after the construction stage. The study aims to investigate the impact of SSP doubling with a stiffened opening on the cyclic behaviour, expand the essential data required by structural designers and quantify the SPSW performance factors. Validated numerical models were adopted to identify the influence of the chosen parameters on the cyclic capacity, energy dissipation, ductility, seismic performance factors (SPF) and stiffness of the suggested method. A finite Element (FE) analysis was performed via Abaqus/CAE software on half-scale single-story models of SPSWs exposed to cyclic loading. The key parameters included the number of SSP layers, the opening size ratios corresponding to the net width of the SSP, and the opening shape. The findings showed that the proposed assembly method found a negligible influence in the shear capacity with opening sizes of 10, 15, 20%. However, a deterioration in the wall strength was observed for openings with sizes of 25% and 30%. The circular opening is preferable compared with the square opening. Moreover, for all the models, the average value of the obtained ductility did not show substantial changes and the ultimate shear resistance was achieved after reaching a drift ratio of 4.36%. Additionally, the equivalent sectional area of the SSP in the twin and triple configuration of the SPSWs demonstrated approximately similar results. Compared with the single SSP layer, the proposed configuration of the twin SSP layer with a stiffened opening suggest to more sufficiency create SSP openings in the SPSW compared to that of other configurations. Finally, a tabular SPF quantification is exhibited for SPSWs with openings.
Auzani Jidin,Nik Rumzi Nik Idris,Abdul Halim Mohd Yatim,Tole Sutikno,Malik E. Elbuluk 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.2
Direct torque control (DTC) of induction machines is known to offer fast instantaneous torque and flux control with a simple control structure. However, this scheme has two major disadvantageous, namely, a variable inverter switching frequency and a high torque ripple. These problems occur due to the use of hysteresis comparators in conventional DTC schemes, particularly in controlling the output torque. This paper reviews the utilization of constant frequency torque controllers (CFTC) in DTC to solve these problems while retaining the simple control structure of DTC. Some extensions of the work in utilizing a CFTC will be carried out in this paper which can further reduce the torque ripple. This is particularly useful for a system which has a limited/low sampling frequency. The feasibility of a CFTC with an extended carrier frequency in minimizing the torque ripple is verified through experimental results.
( Abdul-latif Hamdan ),( Georges Ziade ),( Georges Tabet ),( Rachel Btaiche ),( Ghina Fakhri ),( Firas Yatim ),( Doja Sarieddine ),( Muhieddine Seoud ) 대한폐경학회 2017 대한폐경학회지 Vol.23 No.2
Objectives: To compare the prevalence of phonatory symptoms in menopausal women compared to pre-menopause women with body mass index (BMI) as a confounding variable. Methods: A total of 69 women, 34 menopausal and 35 pre-menopausal were invited to participate in this study. Demographic variables included age, smoking, and BMI. All subjects were asked about the presence hoarseness, loss of high or low frequencies, pitch breaks, throat clearing, dryness in the throat and vocal fatigue. Acoustic analysis was performed and the Voice Handicap Index (VHI)-10 was filled by all the subjects. Results: There was a significantly higher prevalence of throat clearing and dryness in the menopausal group compared to the pre-menopause group with a P value of 0.035 and 0.032 respectively. When BMI was taken into account, there was no statistically significant difference in the prevalence of any of the phonatory symptoms in menopausal women with high BMI and pre-menopause. There was no statistically significant difference in the means of any of the acoustic parameters between the menopausal group and pre-menopausal group. There was no significant difference in the mean VHI-10 between the menopause group and the pre-menopause (P = 0.652). Conclusions: The results of this investigation substantiate the importance of fat as an alternative source of estrogen which can mask some of the phonatory symptoms. (J Menopausal Med 2017;23:117-123)
A Hybrid DTC-DSC Drive for High Performance Induction Motor Control
Auzani Jidin,Nik Rumzi Nik Idris,Abdul Halim Mohamed Yatim,Tole Sutikno,Malik E. Elbuluk 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.5
This paper describes a hybrid induction motor drive system incorporating DTC-hysteresis and Direct Self Control (DSC) schemes to achieve excellent dynamic performance. The control scheme is switched from a circular to a hexagonal flux locus whenever a dynamic condition is encountered. On the other hand, when the motor operates under steady state conditions, a circular flux locus is used. Without major modifications to the simple structure of a basic DTC, hexagonal flux locus operation is established by modifying the flux error status, before it is fed to the look-up table. The feasibility of the proposed hybrid scheme to achieve excellent control performance is verified by experimental results.