Dr. Maher Assaad received a Master degree in electrical engineering/microelectronics IC design from the University of Montreal, Montreal, Canada in 2002, and a Ph.D. in electrical engineering/microelectronics IC design from the University of Glasgow, Glasgow, U.K., in 2009. He has been a senior lecturer in electrical engineering at the University Technology of PETRONAS, Malaysia, and an associate professor in electronic and communication engineering at the American University of Ras Al Khaimah. He is currently an associate professor in electrical engineering at Ajman University, UAE. His research interests include design of analog and digital circuits for sensing and communication systems.
The determination and qualification of sugars in fruits are important for quality control and assurance of horticultural produce. The sugars determine the sweetness levels in fruits. The requirement for a universal technique that is also robust to predict the sweetness of the fruit in a non-destructive fashion is immense. The handheld refractometer, hydrometer, electronic tongues, and high-pressure liquid chromatography (HPLC) in combination with other detectors have long been used to determine the sweetness of horticultural produce. Though these techniques are very accurate and useful, they require extensive sample preparation and are generally time-consuming and expensive. Optical techniques like visible to near-infrared spectroscopy (vis/NIRS) are simple in use and can rapidly predict the sweetness of the fruit in a non-destructive fashion.
The primary role of the oily secretion (meibum) is to ensure tear film stability and retard evaporation. In addition to these is providing ocular surface lubrication, which is necessary for smooth eyelid movements. When a gland is blocked, it is described as a Meibomian gland cyst (MGC), which can be a meibomian cyst, usually referred to as chalazion (eye bump), or in the case of inflammation, it is considered to be a hordeolum (sty or stye). Topical ophthalmic ointments and eyelid heat massages can treat early diagnosed MGC; otherwise, surgical operation is required. The current techniques of diagnosing MGC are usually uncomfortable or invasive, such as examining the tarsal plate after everting the eyelid or by biopsy procedures. The purpose of this work is to propose a non-invasive MGC evaluation and classification technique using hyperspectral imaging and image processing
A rapid and affordable method is desired by the food industry to monitor the quality of the food. A nondestructive and noninvasive testing is desired to determine the optimum harvesting time, monitor changes during storage, and asses the internal quality of the fruits. Time-resolved reflectance spectroscopy (TRS) is used for noninvasive simultaneous measurement of the scattering and the absorption properties of turbid media. In this article, a time-resolved phase reflectance-based nondestructive and noninvasive method is proposed to monitor the internal quality of the fruits. The time-resolved reflectance is determined by the number of internal scatterers based on the mean-free path length of the incident light. The change in the mean-free path due to change in the pigmentation of the internal pulp changes the order of the scatters and, therefore, affects the scattering profile of the reflected light.
Food quality monitoring in the production process is essential. The control of food quality and freshness is of growing interest for both consumer and food industry. Near infrared (NIR) spectroscopy is popular as it does not need any sample preparation. However, NIR spectroscopy is costly and needs reliable calibration. A noncontact, non-destructive optical process is proposed in this work to monitor the quality of the food. It is shown that the reflected phase information can be used to detect the quality of the fruits. The color and the spectral reflectance change with storage. The changes in the spectral feature due to ripening or decay of apples are used to non-destructively monitor the quality of the fruit. A closed relationship between the reflected phase information and degradation is obtained. The developed model is simple, low cost, and does not need extensive calibration as compared to conventional technologies currently used like NIR besides being robust to skin color or appearances of the fruit.
Conventional image steganalysis mainly focus on presence detection rather than the recovery of the original secret messages that were embedded in the host image. To address this issue, we propose an image steganalysis method featured in the compressive sensing (CS) domain, where block CS measurement matrix senses the transform coefficients of stego-image to reflect the statistical differences between the cover and stego- images. With multi-hypothesis prediction in the CS domain, the reconstruction of hidden signals is achieved efficiently. Extensive experiments have been carried out on five diverse image databases and benchmarked with four typical stegographic algorithms.
The control of food quality and freshness is of growing interest for both consumers and the food industry. The optical absorption and scattering properties in fruits, for example, changes with the physiological and biochemical alterations in the tissues during ripening and storage. The absorption and scattering properties are nondestructively monitored using near-infrared (NIR) spectroscopy. NIR has proved to be one of the most efficient and advanced tools for continuous monitoring and controlling of process and product quality in the food processing industry. However, NIR spectroscopy is costly and needs reliable calibration. The basic spectral feature of fruit reflectance in the visible region is considered in this work for the development of algorithms to nondestructively monitor the ripening and decay of apples using phase information of the reflected light.
The paper presents a CMOS interface circuit design for optical pH measurement that can produce an 8-bit digital output representing the color information (i.e., wavelength, l). In this work we are focusing at reducing the component count by design and hence reducing the cost and silicon area. While it could be further optimized for lower power consumption, the proposed design has been implemented using standard cells provided by the foundry (i.e., AMS 0.35 μm CMOS) for proof of concept. The biasing current and power consumption of the fabricated chip are measured at 11 μA and 37 μW respectively using 3.3 V supply voltage. Experimental results have further validated the proposed design concept. The number of detectable colors is eight and can be extended to a higher number without any major change in the architecture.
The paper presents a color sensor system that can process light reflected from a surface and produce a digital output representing the color of the surface. The end-user interface circuit requires only a 3-bit pseudo flash analog-to-digital converter (ADC) in place of the conventional/typical design comprising ADC, digital signal processor and memory. For scalability and compactness, the ADC was designed such that only two comparators were required regardless of the number of color/wavelength to be identified. The complete system design has been implemented in hardware (bread board) and fully characterized. The ADC achieved less than 0.1 LSB for both INL and DNL. The experimental results also demonstrate that the color sensor system is working as intended at 20 kHz while maintaining greater than 2.5 ENOB by the ADC. This work proved the design concept and the system will be realized with integrated circuit technology in future to improve its operating frequency.
A capacitive sensor based measuring system for water content in crude oil is presented. The non intrusive capacitive sensor is made of two semi-cylindrical electrodes which are mounted on outside of the glass tube. The tube is filled with sample under test. The capacitive variation is measured by taking advantage of big dielectric permittivity difference of oil and water. The semi-cylindrical capacitive sensor has ability to detect small capacitance variation (pF) and these variations can be converted into voltage by proposed differential interface circuit. The interface circuit is based on differential sensing technique. Such technique allows the removal of unwanted signals (e.g. temperature, background noise and systematic offset) because they affect both sensors in a similar manner. It however will not auto-compensate for the degradation in sensitivity. Hence, increased accuracy and linearity is achieved by differential sensing technique. Both simulation and actual hardware implementation confirmed the proposed system design. The system is experimentally tested for 0-30% water content in oil and achieved resolution of 0.39%.
An interface circuit design for an optical sensor based on a two-stage cascaded architecture is presented in this paper. The proposed design is a mixed signal solution that provides few advantages in terms of speed, power consumption, higher resolution with smaller number of storage units, and small area for future on-chip integration. Simulation and experimental results for five bits resolution (32 levels) are presented to validate the design. We are aiming for a single-chip integrated solution; however, for a quick proof of concept, the proposed design has been implemented as a PCB using discrete off-the-shelf components. The biasing current and power consumption from the PCB implementation are 192 mA and 1.3 W, respectively, at a 6.75-V supply voltage.
This paper presents a new architecture for a synchronized frequency multiplier circuit. The proposed architecture is an all-digital dual-loop delay- and frequency-locked loops circuit, which has several advantages, namely, it does not have the jitter accumulation issue that is normally encountered in PLL and can be adapted easily for different FPGA families as well as implemented as an integrated circuit. Moreover, it can be used in supplying a clock reference for distributed digital processing systems as well as intra/interchip communication in system-on-chip (SoC). The proposed architecture is designed using the Verilog language and synthesized for the Altera DE2-70 development board. The experimental results validate the expected phase tracking as well as the synthesizing properties. For the measurement and validation purpose, an input reference signal in the range of 1.94–2.62 MHz was injected; the generated clock signal has a higher frequency, and it is in the range of 124.2–167.9 MHz with a frequency step (i.e., resolution) of 0.168 MHz. The synthesized design requires 330 logic elements using the above Altera board.
In this article, an FPGA-based design and implementation of a fully digital wide-range programmable frequency synthesizer based on a finite state machine filter is presented. The advantages of the proposed architecture are that, it simultaneously generates a high frequency signal from a low frequency reference signal (i.e. synthesising), and synchronising the two signals (signals have the same phase, or a constant difference) without jitter accumulation issue. The architecture is portable and can be easily implemented for various platforms, such as FPGAs and integrated circuits. The frequency synthesizer circuit can be used as a part of SERDES devices in intra/inter chip communication in system-on-chip (SoC). The proposed circuit is designed using Verilog language and synthesized for the Altera DE2-70 development board, with the Cyclone II (EP2C35F672C6) device on board.
In this paper, a dual-band impedance transforming power divider is investigated for all types of impedance environments at its ports, irrespective of the locations of the ports. The intuitive design approach utilizes conventional single-band Wilkinson Power Divider (WPD) architecture to provide superior dual-band performance with arbitrary port impedances. The proposed power divider also accords a high degree of design flexibility with high frequency ratios (r) and impedance transformation ratios (k). The presented concept is evaluated and verified by design examples and measurements with a fabricated prototype. The agreement between the simulation and measurement results validates the working of the proposed architecture with arbitrary source and load port impedances at two arbitrary design frequencies.
Iterative learning control (ILC) is well known for producing faster convergence using continuous output tracking based on the given reference plant model. This paper proposes a hybridization of the ILC with the fractional-order predictive PI (FOPPI) for time-delay processes. First, the design of L- and Q-filters for the ILC controller will be obtained using the process model. Then, the obtained filter coefficients are combined and fed to the feed-forward path after the error reduction and control signal conditioning. Finally, the performance of the proposed hybrid ILC-FOPPI controller is evaluated with the conventional PI, fractional-order PI (FOPI), and predictive PI (PPI) controllers over the time-delay processes. Simulation results obtained show the proposed technique’s effective improvement in faster settling and peak overshoot minimization.
This paper proposes a novel hybrid arithmetic–trigonometric optimization algorithm (ATOA) using different trigonometric functions for complex and continuously evolving real-time problems. The proposed algorithm adopts different trigonometric functions, namely sin, cos, and tan, with the conventional sine cosine algorithm (SCA) and arithmetic optimization algorithm (AOA) to improve the convergence rate and optimal search area in the exploration and exploitation phases. The proposed algorithm is simulated with 33 distinct optimization test problems consisting of multiple dimensions to showcase the effectiveness of ATOA. Furthermore, the different variants of the ATOA optimization technique are used to obtain the controller parameters for the real-time pressure process plant to investigate its performance. The obtained results have shown a remarkable performance improvement compared with the existing algorithms.
Background:In the diagnosis and primary health care of an individual, estimation of the pulse rate and blood oxygen saturation (SpO2) is critical. The pulse rate and SpO2 are determined by methods including photoplethysmography (iPPG), light spectroscopy, and pulse oximetry. These devices need to be compact, non-contact, and noninvasive for real-time health monitoring. Reflection-based iPPG is becoming popular as it allows non-contact estimation of the heart rate and SpO2. Most iPPG methods capture temporal data and form complex computations, and thus real-time measurements and spatial visualization are difficult. Method:In this research work, reflective mode polarized imaging-based iPPG is proposed. For polarization imaging, a custom image sensor with wire grid polarizers on each pixel is designed. Each pixel has a wire grid of varying transmission axes, allowing phase detection of the incoming light. The phase information of the backscattered light from the fingertips of 12 healthy volunteers was recorded in both the resting as well as the excited states. These data were then processed using MATLAB 2021b software. Results: The phase information provides quantitative information on the reflection from the superficial and deep layers of skin. The ratio of deep to superficial layer backscattered phase information is shown to be directly correlated and linearly increasing with an increase in the SpO2 and heart rate. Conclusions: The phase-based measurements help to monitor the changes in the resting and excited state heart rate and SpO2 in real time.