Comparison between Different Models for Alpha-particle Range Determination and a New Approach to CR-39 Detector

M. El Ghazaly,T. T. Salama,E. I. Khalil,Kh. M. Abd El Raouf 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.3

An extensive study was carried out to compare different models and a new approach for measuring the alpha-particle range in the CR-39 detector. The CR-39 samples were exposed perpendicularly to alpha particles with energies ranging from 2.5 MeV to 5.5 MeV emitted from ²⁴¹Am. The CR-39 samples were etched in 7.25 N NaOH at (70 ± 0.5) ℃ for different durations. Both the track diameters and the track cone lengths were measured under an optical microscope. The new approach is based on measurement of the track etch rate along the particle’s trajectory as a function of the removal thickness (h). A correlation was found to exist between the removal thickness at the maximum track etch rate (<i>V_Tmax</i>) and the range of alpha particles in the CR-39 detector. The track etch rate data were fitted using the function <i>V_T</i> (<i>h</i>) = a₁ + [a₂ - a₃<i>h</i>] exp[a₄<i>h</i>]. The ranges of alpha particles were determined by setting the first order derivative of the fitting function equal to zero, where h is equal to the range of the alpha particles (R) in the CR-39 detector. Furthermore, the range of the alpha particle in the CR-39 detector was measured using the over-etched track diameter and the track cone length. The theoretical predictions of the alpha-particle ranges were calculated using the SRIM software. A well-known function, <i>R</i>(<i>E</i>) = <i>b₁E^b₂</i>, was used to fit the experimental results and the theoretical predictions. Experiments showed that the determination of the alpha-particle range based on the cone length model was in a good agreement with the theoretical calculations, where the discrepancy was less than that for the over-etched track diameter and the maximum track etch rate models.

Characterization of saturation of CR-39 detector at high alpha-particle fluence

M. El Ghazaly,Nabil M. Hassan 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.3

The occurrence of saturation in the CR-39 detector reduces and limits its detection dynamic range;nevertheless, this range could be extended using spectroscopic techniques and by measuring the netbulk rate of the saturated CR-39 detector surface. CR-39 detectors were irradiated by 1.5 MeV high alphaparticlefluence varying from 0.06 108 to 7.36 108 alphas/cm2 from Am-241 source; thereafter, theywere etched in a 6.25N NaOH solution at a temperature of 70 C for different durations. Net bulk etch ratemeasurement of the 1.5 MeV alpha-irradiated CR-39 detector surface revealed that rate increases withincreasing etching time and reaches its maximum value at the end of the alpha-particle range. It is alsocorrelated with the alpha-particle fluence. The measurements of UVeVisible (UVeVis) absorbance at 500and 600 nm reveal that the absorbance is linearly correlated with the fluence of alpha particles at theetching times of 2 and 4 hour. For extended etching times of 6, 10, and 14.5 hour, the absorbance issaturated for fluence values of 4.05 108, 5.30 108, and 7.36 108 alphas/cm2. These new methodspave the way to extend the dynamic range of polymer-based solid state nuclear track detectors (SSNTDs)in measurement of high fluence of heavy ions as well as in radiation dosimetry.

On the Correlation between the Photoluminescence and the Optical Properties of a Thermally-annealed CR-39 Polymer-based Solid-state Nuclear Track Detector

Mahmoud El Ghazaly 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.1

The induced modifications in the photoluminescence spectra and the optical properties, as well as the correlation between them, of CR-39 polymer-based solid-state nuclear track detectors were investigated after thermal annealing. CR-39 samples were thermally annealed for two hours at different temperatures higher than the glass transition temperature. A linear relationship between the relative mass loss of the CR-39 detector and the annealing temperature was found. The photoluminescence intensity of the pristine CR-39 detector was studied at different excitation wavelengths, where an isosbestic point was observed at 350 nm, which was used as an excitation wavelength. The photoluminescence increased with increasing annealing temperature until temperatures of 200 ℃; thereafter, it decreased at temperatures of 220 and 250 ℃. Moreover, the wavelength of the photoluminescence emission band was subjected to a red shift that increased with increasing annealing temperature. The optical band gaps, direct and indirect band gaps, were obtained from the optical absorption spectra by using a UV-visible spectrophotometer. The direct and indirect band gaps were found to decrease with increasing annealing temperature. A correlation between the photoluminescence peak wavelength and the optical band gaps was found. The spectral peaks red shifted as both of the optical band gaps decreased. We concluded that the reduction in the optical band gaps for both the direct and the indirect band gaps caused the red shift in the photoluminescence peak of the CR-39 detector.

Study of the Optical Properties and the Carbonaceous Clusters in Thermally-annealed CR-39 and Makrofol-E Polymer-based Solid-state Nuclear Track Detectors

M. El Ghazaly 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.7

The induced modifications in the optical properties of CR-39 and Makrofol-E polymer-based solidstate nuclear track detectors were investigated after thermal annealing at a temperature of 200 °C for different durations. The optical properties were studied using an UV-visible spectrophotometer. From the UV-visible spectra, the direct and the indirect optical band gaps, Urbach’s energies, and the number of carbon atoms in a cluster were determined. The absorbance of CR-39 plastic detector was found to decrease with increasing annealing time while the absorbance of Makrofol-E decreased with increasing annealing time. The width of the tail of localized states in the band gap ΔE was evaluated with the Urbach method. The optical energy band gaps were obtained from the direct and the indirect allowed transitions in K-space. Both of the direct and the indirect band gaps of the annealed CR-39 detector decrease with increasing annealing time while in Makrofol-E, they decreased after an annealing time of 15 minute and then showed no remarkable changes for a prolonged annealing times. Urbach’s energy decreased significantly for both CR-39 and Makrofol-E with increasing annealing time. The number of carbon atoms in a cluster increased in the CR-39 detector with increasing annealing time while it decreased with increasing annealing time for Makrofol-E. We may conclude that the CR-39 detector undergoes greater modifications than the Makrofol-E detector upon thermal annealing at 200 °C. In conclusion, the induced modifications in the optical properties of CR-39 and Makrofol-E are correlated with the temperature and the duration of annealing.

On the X-Ray Reflectivity by Poly Allyl Diglycol Carbonate (PADC)

M. El Ghazaly 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.1

X-ray reflectivity via the poly allyl diglycol carbonate (CR-39 polymer sheet) was investigated. X-ray reflectivity was measured for a pristine and a chemically etched CR-39 detector in 6.25N NaOH at (70 ± 0.5) ℃ for different durations. Far from the spectral peak, the reflectivity of the CR-39 polymer sheet has a wide peak at 2θ = 20.1˚, and its intensity is decreased by increasing the etching time. Moreover, the integrated counts under the peaks, C(t_e), vary linearly as a function of the etching time t_e. Data are fitted using a linear function C(t_e) = A+B_e, with fitting parameters A = (3271 ± 170) and B = (−960 ± 84). The reflectivity deterioration is attributed to the increase of CR-39 surface’s roughness due to the chemical etching. The rocking curves of X-ray reflectivity were measured for a pristine and an etched CR-39 polymer sheet. Specular reflections are observed, as well as Yoneda wings, which broaden and move away from the specular reflections due to the increase in the CR-39 surface’s roughness.

Simulation Control of an Active Suspension System Using Fuzzy control & H<SUB>∞</SUB> Control Methods

Khalil Ibrahim,Nouby Ghazaly,Ahmed S.Ali 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10

The motor vehicles industry has shown a mechatronic system with intelligent and autonomous properties. The mechatronics system is integration of hardware components, implementation of advance control function characterize and information technology. Vehicle suspensions systems typically rated by its ability to provide good road handling and improve passenger comfort. Active suspension poses the ability to reduce the traditional design as a compromise between handling and comfort by directly controlling the suspensions force actuators. The mathematical model for the passive and active suspensions systems for quarter car model is proposed. This paper describes fuzzy and H∞ techniques for the automobile active suspension system. The design objective is to provide smooth vertical motion so as to achieve the road holding and riding comfort over a wide range of road profiles. The objective of the proposed control schemes is demonstrated via simulations. The simulation results of the different controllers are compared by using MATLAB/SIMULINK toolbox. Results demonstrate the effectiveness and usefulness of the proposed control method. The simulation results indicate that the proposed active suspension of fuzzy logic control is very effective than the other techniques.

An Efcient Tracking of MPP in PV Systems Using a Newly‑Formulated P&O‑MPPT Method Under Varying Irradiation Levels

Mazen Abdel‑Salam,Mohamed Th. El‑Mohandes,Mahmoud El‑Ghazaly 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.1

This paper proposes a newly-formulated Perturb and Observe (P&O) method for Maximum Power Point Tracking (MPPT) in PV systems. The new formulation considers the efect of solar irradiation level on tracking the maximum power point (MPP). The formulated P&O method is tested under standard test condition (STC) to achieve tracking efciency 99.98% against 98.4% for the conventional P&O method, 99.5% for the improved and 99.85 for the adaptive versions of the P&O method irrespective of the location of the initial operating point to the right or left of the MPP. The higher the tracking efciency, the closer is the operation of the PV module to the MPP with a subsequent capture of maximum electric energy available in the incident solar radiation. At constant irradiation level, the tracking efciency reaches 99.98% for the formulated method against 98.4% for the conventional P&O and 83.6–98.5% for the improved and adaptive versions. The amplitude of output power oscillations around the MPP is reduced to 0.05% of its average value for the formulated method against 1.02% for the conventional P&O, 0.5% for the improved and 0.8% for the adaptive versions. Also, the smaller the oscillations’ amplitude, the closer is the operating point to the MPP. The proposed formulation of P&O tracks successfully the MPP under various conditions including the Ropp irradiation profle, step and ramp changes of irradiation level. However, the conventional P&O method fails to track the MPP under Ropp and ramp changes of irradiation level.

Risk Ranking for Tunnelling Construction Projects in Malaysia

Ghazali, F.E. Mohamed,Wong, H.C. Korea Institute of Construction Engineering and Ma 2014 Journal of construction engineering and project ma Vol.4 No.1

Tunnelling has become a preferred method of construction for road and highway projects in countries with a lot of hilly slope geological conditions such as found in Malaysia. However the construction works of a tunnelling project are usually complicated and costly, which consequently impose great risks to the parties involved. This paper identifies the key significant risks and sub-risks for tunnelling construction projects in Malaysia through a case study. Interview has been used as the solitary means to determine the significant risks from contractor's eleven key project personnel who were directly involved in the tunnelling construction such as consultant, construction manager and tunnel engineers. The importance of the risks identified is then prioritised and ranked via the Analytic Hierarchy Process (AHP)'s pairwise comparison approach to determine their criticality towards a successful delivery of project. As a result, three key risks have been identified as significant for the tunnelling case study project, namely health and safety, cost overrun in construction and time overrun in construction. Two sub-risks each of the latter categories, which are cost underestimation and unforeseen events (cost overrun in construction) as well as plant and machinery failure and delay in material delivery (time overrun in construction), have occupied the top five overall risk ranking.

Development of a new correlation for pre-dry out evaporative heat transfer coefficient of R290 in a microchannel

Ghazali Muhammad Aliff Haikal,Mohd-Yunos Yushazaziah,Pamitran Agus Sunjarianto,Jong-Taek Oh,Mohd-Ghazali Normah 대한설비공학회 2022 International Journal of Air-Conditioning and Refr Vol.30 No.1

Although many correlations have and are being developed for two-phase heat transfer coefficient correlation in microchannels, none has the desired accuracy yet. This paper presents prospective improvements in the convective heat transfer coefficient correlation accuracy for the dry-out conditions; when the heat transfer coefficient drops at a certain vapor quality. An accurate heat transfer coefficient forecast is needed to minimize over or under design, conserve energy and material, and maximize the performance. R290 has been reported to be more energy efficient than R22. A new correlation relevant for R290 across 831 sets of experimental data points in a microchannel was generated by optimizing six variables in the nucleate boiling suppression factor, S, and force convective factor, F, of a selected superposition type correlation. The new correlation was optimized for saturation temperature ranging between 5 and 25 °C, diameter ranging between 1.0 and 6.0 mm, heat flux ranging between 2.5 and 60 kW/m 2 , and mass flux ranging between 50 and 500 kg/m 2 s. The MAE was reduced from 21.84 to 17.02% for pre-dry out data. The new correlation may be utilized to estimate the heat transfer coefficient of R290 in heat transfer analysis in a microchannel under the investigated operating conditions. The optimization approach utilized here has the potential of continuously improving the MAE of any heat transfer correlation for any refrigerants considered.

Exploring the Experiential Aspect of Home-Stay in Kampung Lonek Using Diary Method

Ghazali Musa,Kalsom Kayat,Thinaranjeney Thirumoorthi 세계문화관광학회 2008 Conference Proceedings Vol.9 No.0

Home-stay is one of the Malaysian government efforts to diversify its cultural tourism product. Tourists are adopted by their foster families and experience the traditional life in Malay villages. This study explores the experiential aspects of home-stay holidays in Kampung Lonek using diary method. Nineteen diaries were returned and analyzed using NVIVO. The paper proposes a home-stay experiential model which explains the phases of travel experience including the on-site experience. Among the on-site experience dimensions are 'Environmental Experience', 'Activity, Culture and Knowledge Experience' and 'Human Interaction Experience'. The uniqueness of home-stay experience is discussed along with some management implications.