Hilmi Sanusi

Modeling of electrical resistivity and maximum dry density in soil compaction measurement

This paper presents the mathematical relationship of electrical resistivity and dry density in compacted soil through electrical signal for geotechnical investigations. Monitoring of the compacted soil through electrical conductivity plays an important role in the construction of highway embankments, earth dams and many other engineering structures. Conventionally, soil compaction is measured through the estimation of maximum dry density at optimum moisture contents in laboratory tests. This conventional testing method is very tedious and costly especially when a lot of samples are involved. In this work, a mathematical model is developed to estimate the soil compaction on-site through electrical resistivity corresponding to the percentage of moisture contents in the compacted soil. The practical usage of the derived mathematical model is demonstrated using several soil samples for various types of soil.

A high speed and low power voltage controlled ring oscillator for phase locked loop circuits

This paper presents the design of a high speed and low power voltage controlled ring oscillator. The proposed design is suitable for phase locked loop circuits. The ring oscillator operates at 5GHz and designed by 0.13 μm CMOS technology. Seven stages of inverters are built to construct the oscillator, forming 126 bit vectors. The frequency is controlled by a tri-state gate inverter, and the first inverter is exchanged by a NAND-gate to drive the oscillator to idle mode. The optimization design and layout are done using L-EDIT® software to make the oscillator as small as possible. In addition, H-spice and L-EDIT tools are used in the analysis and simulation to verify the predicted performance. The optimized ring oscillator is then compared with the previous design done by other researchers. It reveals that the ring oscillator is able to operate with 2V supply, occupying an area of about 0.42 × 1.29 mm2 and consuming around 50.85 mW.

Simple phase angle measurement of two periodic signals

In this paper, a simple algorithm to measure the phase angle between two periodic signals is presented. It uses the digitized samples of the two signals and works on simple data sorting and interpolation techniques. The algorithm sorts for the location at which the changing of the signals from negative to positive takes place in the given data sequences. It localizes the exact zero crossing by interpolating the signals of the sorted locations and deduces the phase angle based on the localized zero crossing of the two sequences of the sampled signals. The algorithm has been implemented in the 16-bit microcontroller and the performance of the developed algorithm based on simulation and practical results is presented. The novelty of the proposed algorithm is in the simplicity of the technique to determine the phase angle which makes it possible to be implemented in real time and reduces the overall cost of the system.

Model with artificial neural network to predict the relationship between the soil resistivity and dry density of compacted soil

This paper presents a technique to obtain the outcomes of soil dry density and optimum moisture contents with artificial neural network ANN for compacted soil monitoring through soil resistivity measurement in geotechnical engineering. The compacted soil monitoring through soil electrical resistivity shows the important role in the construction of highway embankments, earth dams and many other engineering structure. Generally, soil compaction is estimated through the determination of maximum dry density at optimum moisture contents in laboratory test. To estimate the soil compaction in conventional soil monitoring technique is time consuming and costly for the laboratory testing with a lot of samples of compacted soil. In this work, an ANN model is developed for predicting the relationship between dry density of compacted soil and soil electrical resistivity based on experimental data in soil profile. The regression analysis between the output and target values shows that the R2 values are 0.99 and 0.93 for the training and testing sets respectively for the implementation of ANN in soil profile. The significance of our research is to obtain an intelligent model for getting faster, cost-effective and consistent outcomes in soil compaction monitoring through electrical resistivity for a wide range of applications in geotechnical investigation.

Proportional Derivative Controller Using Discrete Kalman Filter Estimation Method for Spacecraft Attitude Control

This paper deals with the objective of controlling a satellite by driving a six-state discrete Kalman Filter to estimate angular rates of satellite base on control sensor noisy data. A typical satellite is assumed in a special orbit and orbital angular velocity and orbital angular acceleration are established. For completion of simulation linear dynamics model of satellites and environment disturbances model such as solar pressure and gravity gradient torque is derived as well. The simulation is progressed at discrete ten second which assumed as data updating rate from sensor. The noisy measurements are produced by sensor and these data is sent to the discrete Kalman Filter part to estimate the attitude and attitude rate. A right balance for Plant noise covariance matrix is determined and also results show that the rate estimates are appropriate for space missions.

PD controller for three-axis satellite attitude control using discrete Kalman Filter

This paper explains driving a six-state discrete Kalman Filter to estimate angular rates of satellite base on control sensor noisy data. A typical satellite is assumed in a special orbit and orbital angular velocity and orbital angular acceleration are established. For completion of simulation linear dynamics model of satellites and environment disturbances model such as solar pressure and gravity gradient torque are derived. The simulation is progressed at discrete ten seconds, which assumed as the data updating rate from sensor. Noisy measurements are produced by sensor and these data are sent to the discrete Kalman Filter part to estimate the attitude and attitude rate. Final results indicate that these rate estimates are appropriate for space missions.

Open Platform Orbit Determination Systems Using a Mixture of Orbit Estimator and Orbit Propagator

This paper describes a flexible orbit determination method that uses a mixture of orbit estimator and orbit propagator with the ability to perform corrections if the ephemeris from GPS, ground track or other method is obtainable. The satellite uses various sensors including Global Positioning Systems (GPS) or trusted orbit propagator in order to obtain the orbital information with the minimum delay and error at the lowest cost. Orbit propagator uses an orbital dynamic model where the analytic form needs to be constantly updated in order to maintain its accuracy and the integrator needs heavy computation but both constitute the error propagation in which the accuracy depends on the complexity and selection of orbital elements. Orbit estimator uses set of sensors data to produce an estimate where the accuracy depends on measurement noise characteristic and the model used. To avoid divergence, a sensible process and measurement noise model are selected. The orbit estimate is derived from an Extended Kalman Filter (EKF) while the Variation of Parameters (VOP) is used to propagate from one state to the other. Any obtainable ephemeris will be used as an initial state. The EKF uses the Position and Velocity elements as they possess dynamics that are beneficial to the estimator. The propagator uses the Keplerian elements as it consists of slow varying elements [a, e, i] and fast varying elements [ω, Ω, υ]. The EKF will be more difficult to diverge towards any abrupt disturbance if the slow varying elements from the orbit propagator are blended with the orbital elements produced by the orbit estimator and prevent the estimator from diverging.

Faster 2-D representation of geotechnical characteristics using MASW method

This paper presents how faster two dimensional (2-D) tomography of soil layers is obtained in geotechnical characteristics through multi-channel analysis of surface wave (MASW) method. MASW is developed as a new technique incorporating multiple receivers and 2-D wave-field transformations to obtain better performance in surface wave analysis. Incorporating 2-D tomography technique with multi-channel analysis offers an efficient and cost effective technique in soil site investigations. In the previous research, the Geo-SW@T software was designed and developed with collecting a lot of records including programming array technique to show the 2-D tomography in near surface soil profiling. To make a 2-D tomography of soil profile based on the past planned MASW technique is time consuming for collecting large database through 2-D array of programming language. In this paper, a new idea is established to obtain faster performance in soil tomography profile using array and sub-array technique in MASW. The performance of newly developed tomography technique with MASW method is estimated as faster and important tomography system for using one single record in soil characterizations rather than arranging of multiple records.

Comparison of solar UVA and UVB radiation measured in Selangor, Malaysia

The solar ultraviolet A (UVA) radiation data was measured at Physics Building, Universiti Kebangsaan Malaysia (2°55’ N, 101°46’ E, 50m asl) by the Xplorer GLX Pasco that connected to UVA Light sensor. The measured solar UVA data were compared with the total daily solar ultraviolet B (UVB) radiation data recorded by the Malaysian Metrological Department at Petaling Jaya, Malaysia (3° 06’ N, 101° 39’ E, 50m asl) for 18 days in year 2007. The daily total average of UVA radiation received is (298±105) kJm−2 while the total daily maximum is (600±56) kJm−2. From the analysis, it shows that the values of UVA radiation data were higher than UVB radiation data with the average ratio of 6.41% between 3–14%. A weak positive correlation was found (the correlation coefficient, r, is 0.22). The amount of UVA radiation that reached the earth surface is less dependence on UVB radiation and the factors were discussed.

Zenith angle dependence of muon rate at ground level in Bangi

The zenith angle distribution of the ground level muon rate has been measured in Bangi by using muon telescope. The experiments have been done in Muon Laboratory and at the rooftop of the Physics Building, Faculty of Science and Technology, UKM Bangi. The method used to carry out the experiments are by using simultaneous muon strikes on two Geiger-Muller (GM) radiation monitors that are arranged in telescopic mode then counts will accumulate in the counter. These commercially-available GM tubes provide simpler, cheaper and convenient alternatives to muon telescope for the detection of muons at ground level. The counts were manually and automatically monitored and data from January 2007 to March 2007 and January 2009 to March 2009 were recorded. The zenith angle distribution of the muon rate has been measured between 0° and 90° in steps of 15°. The muon zenith angle distributions vary with the zenith angle, θ, with roughly a cos2θ shape were described.