Image Reconstruction Validation for CMOS Linear Image Sensor Based Tomography System

Nowadays, the fast-moving industries need a low cost, accurate, low power consumption, non-invasive and safe method for monitoring and tracking of the conveying and manufacturing process. There is many tomography based systems available in the industry, however, with limitations. This project aims to solve industrial problems of monitoring objects inside a transparent conveying pipe and determine the characteristic of the objects such as size, quantity and position. This is done through the image reconstruction of data acquired from Complementary metal-oxide-semiconductor (CMOS) linear image sensor based on optical tomography system. Data from four projections of laser are used to avoid the aliasing problem that may occur due to fewer projections. The image can be reconstructed by using linear back projection technique. The image will undergo image processing to enhance the image for better visualization of the object. Theoretical and experimental image are compared to validate the image reconstruction. As a result, the position, size and number of a symmetrical and solid object can be determined accurately from the reconstructed image. For further improvement, the number of projection may be increased

Textile Diamond Dipole and Artificial Magnetic Conductor Performance under Bending, Wetness and Specific Absorption Rate Measurements

Textile diamond dipole and Artificial Magnetic Conductor (AMC) have been proposed and tested under wearable and body centric measurements. The proposed antenna and AMC sheet are entirely made of textiles for both the substrate and conducting parts, thus making it suitable for wearable communications. Directive radiation patterns with high gain are obtained with the proposed AMC sheet, hence minimizing the radiation towards the human body. In this study, wearable and body centric measurements are investigated which include bending, wetness and Specific Absorption Rate (SAR). Bending is found not to give significant effect to the antenna and AMC performance, as opposed to wetness that yields severe performance distortion. However, the original performance is retrieved once the antenna and AMC dried. Moreover, notable SAR reduction is achieved with the introduction of the AMC sheet, which is appropriate to reduce the radiation that penetrates into human flesh

FCS-MPC-Based Current Control of a Five-Phase Induction Motor and its Comparison with PI-PWM Control

This paper presents an investigation of the finite-control-set model predictive control (FCS-MPC) of a five-phase induction motor drive. Specifically, performance with regard to different selections of inverter switching states is investigated. The motor is operated under rotor flux orientation, and both flux/torque producing (d-q) and nonflux/torque producing (x-y) currents are included into the quadratic cost function. The performance is evaluated on the basis of the primary plane, secondary plane, and phase (average) current ripples, across the full inverter's linear operating region under constant flux-torque operation. A secondary plane current ripple weighting factor is added in the cost function, and its impact on all the studied schemes is evaluated. Guidelines for the best switching state set and weighting factor selections are thus established. All the considerations are accompanied with both simulation and experimental results, which are further compared with the steady-state and transient performance of a proportional-integral pulsewidth modulation (PI-PWM)-based current control scheme. While a better transient performance is obtained with FCS-MPC, steady-state performance is always superior with PI-PWM control. It is argued that this is inevitable in multiphase drives in general, due to the existence of nonflux/torque producing current components. © 1982-2012 IEEE

Effect of cement additive and curing period on some engineering properties of treated peat soil

Peat soil is characterized by its high content of decomposed organic matter. Majority of areas occupied by peatland have been developed for agriculture sectors such as pineapple cultivation and oil palm. Due to its geotechnical drawback characteristics such as highly compressibility and low shear strength, peat soil is classified as problematic soils and unstable for engineering structures. Lack of suitable and expensive price of lands, peatland will be an alternative option for future development. Prior to construction works, stabilization of peat soil should be performed to enhance its engineering characteristics. This paper presents the effect of cement and curing period on engineering properties of the cement-treated peat soil. Some engineering variables were examined including the compaction behaviour, permeability and unconfined compressive strength (UCS). The Atterberg limit test was also carried out to examine the influence of cement addition on peat soil. The cement-treated peat soils were prepared by adding varying amount of ordinary Portland cement (OPC) ranging between 0% and 40% of dry weight of peat soil. In order to examine the effect of curing, the treated samples were dried at room temperature for three and seven days while for UCS tests samples were extended to 28 days prior to testings. The results showed that the liquid limit of treated soil decreased with the increase of cement content. Maximum dry density (MDD) increased while optimum moisture content (OMC) dropped with the increase in cement content. Permeability of treated soil decreased from 6.2×10-4 to 2.4×10-4 ms-1 as cement content increase from 0% to 40%. In contrast, the UCS tests indicated an increase in uncompressive strength with the increase in cement contents and curing period. The liquid limit and permeability were also altered as curing periods were extended from three to seven days. This study concluded that geotechnical properties of peat soil can be stabilized using ordinary cement and by modification of the curing periods

A Fault-Tolerant Two-Motor Drive With FCS-MP-Based Flux and Torque Control

Independently controlled multi-motor drives are typically realized by using a common dc link and independent sets of three-phase inverters and motors. In the case of an open-circuit fault in an inverter leg, one motor becomes single-phase. To enable continued controllable operation by eliminating single-phasing, the supply for the motor phase with the faulted inverter leg can be paralleled to a healthy leg of another inverter, using hardware reconfiguration. Hence, the two motors are now supplied from a five-leg inverter, which has inherent voltage and current limitations. Theoretically, violating the voltage limit leads to inverter over-modulation and large torque oscillations. It is shown here that the finite-control-set model predictive control (FCS-MPC), designed to control the machines’ stator flux and torque, can consider the inherent voltage limit dynamically in the control loop. Apart from preserving the independent control of the two machines, the additional constraint consideration significantly widens the operating speed ranges of the machines. In particular, it is shown that whenever the voltage limit is entered, the controller reduces the stator flux level automatically, without requiring external flux reference change. The obtained performance is illustrated using experimental results and is also compared to the conventional two-motor field-oriented control scheme. The control concept is thus fully experimentally verified

Development of a semi-active car suspension control system using magneto-rheological damper model

In this paper, the development of a semi- active suspension control of quarter car model using fuzzy-based controller has been done. The quarter car model to be used here can be described as a nonlinear two degrees of freedom system which is subject to excitation from different road profile. The semi-active control is designed as the fuzzy control inferred by using two single input rule fuzzy modules, and the road model is used as the control force is released by actuating an electromagnetic shaker. To implement semi-active suspension system experimentally, the MR damper is used here as the adjustable damper. The MR damper is a control device that consists of a hydraulic cylinder filled with magnetically polarizable particles suspended in a liquid. MR dampers dissipate vibration by absorbing energy. Magnetorheological (MR) fluids dampers are very effective to control vibration, which use MR fluids to produce controllable damping force and provide both the reliability of passive systems and the facility of active control systems with small power supply. Due to their mechanical simplicity, high dynamic range, low power requirements, large force capacity, and robustness, offer an attractive means of vibration protection. The objectives of this are modeling of semi-active suspension system, developing controller and understanding the characteristics of the MR damper to provide effective damping for the purpose of suspension isolation or suppression car model. In this work pid, fuzzy logic and fuzzy-hybrid controller are used to control semi-active car suspension system

Current Control Methods for an Asymmetrical Six-Phase Induction Motor Drive

Using the vector space decomposition approach, the currents in a multiphase machine with distributed winding can be decoupled into the flux and torque producing α-β components, and the loss-producing x-y and zero-sequence components. While the control of α-β currents is crucial for flux and torque regulation, control of x-y currents is important for machine/converter asymmetry and dead-time effect compensation. In this paper, an attempt is made to provide a physically meaningful insight into current control of a six-phase machine, by showing that the fictitious x-y currents can be physically interpreted as the circulating currents between the two three-phase windings. Using this interpretation, the characteristics of x-y currents due to the machine/converter asymmetry can be analyzed. The use of different types of x-y current controllers for asymmetry compensation and suppression of dead-time-induced harmonics is then discussed. Experimental results are provided throughout the paper, to underpin the theoretical considerations, using tests on a prototype asymmetrical six-phase induction machine. © 1986-2012 IEEE

Miniaturize size of dual band branch-line coupler by implementing reduced series arm of coupler with stub loaded

An extremely reduced size branch-line coupler operating at dual frequencies of WLAN band 2.45 GHz and 5.8 GHz is presented which is 58% smaller compared to the conventional design. The technique presented introduces the combination method in which the length of series lines is half than the length of shunt branch lines and the loading of stub tapped to the center of the series branch line that forms the couplers arms. Furthermore, the coupler accurately divides the input signal by two parts with the same power and 90° phase difference. Also, the reflection coefficient and the isolation are as good as conventional one. The agreement of the measurement and simulated confirms the theory and validates the proposed coupler design. The measurement shows 33.83% and 9.22% bandwidth for the lower and upper frequency, respectively

Concentrated photovoltaic thermal systems:A component-by-component view on the developments in the design, heat transfer medium and applications

The need of the hour in present world scenario is to reduce the emission of greenhouse gases and environmental pollution whilst satisfying the world energy demands. The most promising and readily available source of energy over the whole world is solar energy. One of the ways of taping this energy into useful energy is using Concentrated Photovoltaic Thermal systems. The paper presents the advanced comprehensive review on the design components of Concentrated Photovoltaic Thermal, heat transfer medium, recent application area such as Tissue Dyeing, domestic hot water, Organic Rankine Cycle, and the economic aspect of the Concentrated Photovoltaic Thermal system. Furthermore, the review paper simplifies the classification into two systems namely thermally coupled and thermally decoupled systems. Concentrated Photovoltaic Thermal shows potential to deliver better gains compared to Concentrated Photovoltaic, Photovoltaic and Photovoltaic Thermal. But matching the different components like the heat transfer component and the medium for specific use is an area that requires research. Therefore, this review concentrates more on the advantages and limitations of using different heat transfer components and heat transfer medium. The benefits of this paper would be the understanding of the components of the heat transport system like fins, microchannel, storage tank and underground heat exchangers and the fluid used in the Concentrated Photovoltaic Thermal integrated system like water, air, nanofluids, Phase Change Materials. It is found that the heat transfer device performance is limited due to its large area, thermal losses, mirror effect on the thermal and electrical efficiencies, and the temperature difference between the sink and device. Likewise, the performance of the heat transfer fluid is dependent on the mass flow rate, thermal mass, viscosity, density, time and the required temperature. Finally, for economic feasibility of the Concentrated Photovoltaic Thermal system requires the need for a grid connected system with properly sized system with feed-in-tariff and carbon incentives. Furthermore, the recommendation for heat transfer device, medium and economic aspect is also presented. However, more experimental research is required to further understand the compatibility of each components with Concentrating Photovoltaic Thermal System as presented in way forward

Design of a Low Voltage Class AB Variable Gain Amplifier (VGA)

A variable gain amplifier (VGA) is one of the most significant component in many applications such as analog to digital converter (ADC). In communication receiver, VGA is typically employed in a feedback loop to realize an automatic gain control (AGC), to provide constant signal power to baseband analog-to-digital converter (ADC) for unpredictable received signal strengths. Gain range, power consumption and bandwidth of ADC are strongly influenced by the performance of operational amplifier. VGA is the key element for amplifying process in ADC. However, current class AB VGA is experiencing the limit of bandwidth, which is not suitable for high speed automatic gain control AGC. In order to overcome these limitations a high linearity and wide bandwidth of VGA is indispensable. The aim of this research is to get higher gain and larger bandwidth for VGA. In this research, a low cost, low power voltage and wide bandwidth class AB VGA is designed to mitigate this constraint. Superiority of the proposed VGA has been confirmed by circuit simulation using CEDEC 0.18-μm CMOS process with the help of tools from Mentor Graphics in designing a 100-MHz VGA under 1V supply voltage draining total static power consumption less than 125uW. The results show that the circuit is able to work with high linearity and wide bandwidth by varying Rf and Rs. Therefore, the frequency response (Gain) and the wide bandwidth of this class AB VGA is better than previously reported class AB VGA. Consequently, this modified class AB VGA is appropriate for high speed applications