A. Ishak

Process controllability for flow control system using Ziegler-Nichols (ZN), Cohen-Coon (CC) and Chien-Hrones-Reswick (CHR) tuning methods

The controllability of the process depends on the values need to be chosen for the proportional, integral and derivative constants. The value of proportional, integral and derivative can be estimated using various tuning method. The purpose of this study is to compare the performance of various proportional, integral and derivative controller tuning methods for flow control system. A Tangent Method and Reformulation Tangent Method were compared in this paper to perform the open-loop test. From the open-loop test, the value of response rate, dead time and time constant were obtained. The controller parameters from open-loop test were used in tuning rule to get the optimum value of proportional, integral and derivative gains. The tuning methods used in this paper were Ziegler-Nichols, Cohen-Coon and Chien-Hrones-Reswick. Performance comparison and analysis of the three proportional, integral and derivative tuning were based on percent overshoot, settling time, rise time and integral absolute error. The fine tuning technique has used to improve the result which the value of proportional and integral gains were tuned. The result showed that Ziegler-Nichols and Chien-Hrones-Reswick tuning methods provided better performance compared to CC tuning method.

Surface Morphology and Compositional Analysis of Undoped Amorphous Carbon Thin Films via Bias Assisted Pyrolysis-CVD

Amorphous carbon (a:C) were successfully deposited on the silicon surfaces via bias assisted pyrolysis-CVD in the range between 350oC to 500oC with constant of negative bias -50V in 1 hour deposition. The heated of palm oil at about 150oC was vaporized then used for deposited onto p-type silicon substrates. The deposited thin films were characterized by using field emission scanning electron microscopic (FESEM), energy dispersive analyser x-ray (EDAX). We have found carbon element at about 0.15 keV from EDAX with surface morphology formed a nano-ball like structure at 450oC of palm oil precursor. These results indicated deformation of physical and structural thin films caused by applied negative bias and the temperature.

Deposition of Amorphous Carbon Thin Films via Bias Assisted Pyrolysis-CVD

The as deposited amorphous carbon (a-C) thin films were successfully deposited by using ethanol and palm oil precursors via a novel bias assisted pyrolysis-CVD ranging from 300oC to 550oC with constant of negative bias -40V and -50V in 3h and 1h deposition. The thin films were characterized by atomic force microscopic (AFM), field emission scanning electron microscopic (FESEM), and I-V measurement. The resistivity of as deposited a-C thin films using ethanol precursor at 300oC, 350oC, 400oC and 500oC were 9.57 x106Ω/cm, 9.44 x106Ω/cm, 9.81 x105Ω/cm and 337738.124 Ω/cm respectively and conductivity were 1.00445 x10-7 cm/Ω, 1.0593 x10-7,cm/Ω, 1.01963x10-6 cm/Ω, and 2.67825 x10-6 cm/Ω. For palm oil precursor (400oC-550oC), the resistivity were calculated, 3.83x104Ω/cm, 1.32x104Ω/cm, 3.77x104Ω/cm, and 4.19x105Ω/cm respectively while conductivity were 2.61 x 10- 5 cm/Ω, 7.60 x 10- 5 cm/Ω, 2.65 x 10- 5 cm/Ω, and 2.39 x 10- 6 cm/Ω. The samples showed all the resistivity values were in the range of semiconductor. The results showed that increasing temperature decreased resistivity of thin films for ethanol precursor. The resistivity thin films obtained from palm oil precursor were smaller as compared with ethanol precursor.

Reformulated tangent method of various PID controller tuning for air pressure control

The optimum proportional(P), integral(I) and derivative(D) constants can be estimated using tangent method and proper tuning rule for process stability. The purpose of this paper is to compare the performance of various controller tuning methods for controlling the process of air pressure control trainer model SOLTEQ SEl2l. The simplest open loop test on actual plant has been performed using a new Reformulated Tangent Method (RTM). The optimum PID value is set to the real plant based on Ziegler-Nichols (ZN), Chien-Hrones-Reswick (CHR) and Chien et. al. (Chien) tuning rules. The PID Tuner software is used to simulate the response to be compared with the real plant response. The plant is connected to a Yokogawa Centum CS 3000 R3 Distributed Control System (DCS). The performance of each method is analyzed in term of percent overshoot(%OS) settling time(Ts), rise time(Tr) and integral absolute error(IAE).

Application of numerical technique in tangent analysis of a discrete step response data

Tangent analysis is the conventional method used to analyze an open-loop step response curve. It is done by drawing a tangent line at the steepest point of the step response curve. The process dynamics such as dead time and response rate can be obtained from the analysis. Later, this information is applied to the open-loop tuning rule for optimum PID calculation. With current developments in paperless recorders and digital computer control, the step response curve is available in discretized form. Accordingly, the process dynamics of the discrete step response can be analyzed numerically. It is, therefore, the intention of this paper to present the application of numerical analysis in extracting the process dynamics from discrete step response data.

P-type properties of micro and nano-structured carbon films from hydrocarbon palm oil in photovoltaic heterojunction solar cell applications

The micro and nano-structured amorphous carbon as p-type films prepared from natural palm oil precursor for heterojunction solar cell were presented. Field-emission scanning electron microscopy (FESEM) revealed the micro and nano structured films had particle size in the range of 382 nm to 689 nm and 28 to 34 nm, respectively. The energy-dispersive spectroscopy (EDS) showed the existing of carbon in micro-structured amorphous carbon film and carbon together with boron in nano-structured amorphous carbon film. Solar simulator analysis results showed an open circuit voltage (VOC), current density (JSC), fill-factor(FF) and conversion efficiency (η) of Au/a-C/n-Si/Au were 264.62 mV, 1.50434 mA/cm2, 0.32632, and 0.130154 %, respectively. Meanwhile, the VOC, JSC, FF and η of Au/a-C:B/n-Si/Au solar cell were 271.25 mV, 14.91723 mA/cm2, 0.33582, and 1.542622 %, respectively. The conversion efficiency was increased as the p-type film was in nanostructure form.

Structural and electrical properties of nanostructured TiO 2 thin film at low molarity

Titanium dioxide, TiO2 is a semiconductor material which has many useful properties. This paper is to clarify the use of sol-gel method in the production of nanostructured TiO2. Since sol-gel method is quite simple to compare with sputtering or pyrogenic process. The solution concentration will be varied in low molarity of 0.06M, 0.04M and 0.02M. Spin coating was used to deposit the nanostructured TiO2 on to the glass substrate and the surface morphology was observed using the Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FESEM). The electrical properties were investigated by using two probe current-voltage (I-V) measurements to study the electrical resistivity behavior hence the conductivity of the film. Based on the result, higher the molarity of TiO2, the surface become more uniform and the IV becomes much better. The best thin film characteristic by low molarity parameter from 0.06M, 0.04M, 0.02M and 0.01M is the one with lowest molarity of 0.01M thin film.

Process controllability for air temperature oven system using open-loop Reformulated Tangent Method

This paper presents the effect of various control tuning methods to the controllability of air temperature oven system. The simplest open loop test on actual plant has been performed using a Reformulated Tangent Method (RTM). Three PID tuning rules namely Ziegler Nichols (Z-N), Cohen Coon (C-C), and Chien, Hrones & Reswick (CHR) are used in this work. The plant is connected to Distributed Control System (DCS). The performance of these control tuning rules are evaluated in term of their closed loop characteristics such as percent overshoot (% OS), settling time (Ts), rise time (Tr) and integral absolute error (IAE). The results of this study showed that Cohen-Coon tuning method give best performance to the controllability of air temperature oven system as compared to the other rules.

Electrical and structural properties of nanotetrapod zinc oxide thin films prepared with different deposition temperature

Nanotetrapod zinc oxide (ZnO) thin films have been deposited by thermal chemical vapor deposition (TCVD) technique. The films were deposited at 700°C and 800°C to study the temperature effect of physical properties of the nanotetrapod ZnO thin films. From XRD result shows the highest peak can observed from sample 700°C at (002) orientation. It was found that the size of nanotetrapod increased with increased of deposition temperature. The energy dispersive X-ray spectrometer (EDX) spectrum shows that the grown product contains zinc and oxygen only. At 800°C show the minimum of resistivity for the thin film which is 1.10 ohm. cm. Photoluminescence measurement shows a sharp peak ultraviolet emission at 380 nm and high intensity visible peak at 700°C because of defect due to oxygen vacancy and crystallization of ZnO nanotetrapod.

Various PID controller tuning for air temperature oven system

Temperature controllers are needed in any situation requiring a given temperature be kept stable. This can be in a situation where an object is required to be heated, cooled or both and to remain at the desired temperature, regardless of the changing environment around it. The purpose of this study is to compare the performance of three controller tuning methods for an air oven temperature control system. The controller parameters, response rate and dead time are determined by using Reformulated Tangent Method in open-loop test. Then, the optimum Proportional-Integral-Derivative value are determined by using Ziegler-Nichols, Chien et al. and Takahashi tuning methods. The performance of each tuning rule is analyzed in the closed-loop characteristics such as percent overshoot, setting time, rise time and integral absolute error. The fine tuning technique was implemented to improve the result which the value of Proportional-Integral-Derivative gains were tuned. The result presented that the Ziegler-Nichols tuning method give better performance compared to Chien et al. and Takahashi tuning methods.