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The output voltage of a Multilevel Inverter (MLI) can be controlled using various low and high frequency modulation strategy. Apart from meeting the load voltage demand, the modulation strategy also tries to reduce the harmonics present in the output voltage waveform. In this paper, a novel modulation strategy, a Variable Structure Nearest Level Modulation (VSNLM) has been proposed with the objective to reduce the Total Harmonic Distortion (THD) thus giving better output voltage quality and smoother control. The development of the mathematical model and subsequent analysis has been carried out. Moreover, the proposed modulation scheme has been implemented on 7, 9, 11, and 13 level Cascaded H Bridge inverter and a generalized mathematical model of the proposed scheme has been developed. A comparison of the proposed strategy with the conventional NLC is presented in the paper. The results confirm the superior performance of proposed strategy in terms of THD. Experimental results have also been presented for validation.

A numerical simulation-based study is undertaken in order to assess the performance of plane wave imaging in the concrete medium for damage detection. The random scattering of ultrasonic field by the aggregates in the concrete medium incorporates higher background noise in the reconstructed subsurface images using conventional imaging algorithms. This noise can at times mask the imaged defects either partially or completely and hence reducing the capability of damage detection of subsurface images. Also defects located closer to the top surface fail to appear in the reconstructed images. Plane wave imaging technique proposed in this study, on the other hand is able to significantly reduce the incoherent noise as well as other undesired imaging artefacts. This improves the damage detection capability since the image contrast gets improved significantly. The proposed technique is able to image the cracks located at the shallow depth of the medium and at the same time mapping the aperture facing geometry of the defects present in the simulated concrete medium. The reconstruction of subsurface images using plane wave imaging is done by post-processing the full matrix data and hence does not require the phased arrays which can be practically difficult to use on concrete structures.

In this paper a modified H-Bridge based multilevel inverter topology has been implemented using genetic algorithm to reduce the total harmonic distortion present in the multilevel inverter output. Using GA based optimization technique, the switching angles at which the THD is minimum have been calculated and the THD obtained with the proposed technique is reduced drastically. Detailed mathematical formulation is presented in the paper, and computer simulation is performed in MATLABo/Simulink. The results are obtained at different loads and presented and discussed in the paper.

Partially shaded condition (PSC) is one of the major problems in large photovoltaic generation systems. It causes losses in output power and hot spot effects. Under PSC, PV characteristic curve exhibits multiple peaks having one global maximum power point and multiple local maximum power points. Tracking the global maximum power point is one of the main challenges the design engineers have to face. The paper presents the recent work done on the development of Global Maximum Power Point Tracking (GMPPT) algorithms under partial shading condition and their comparative analysis. To have focus on GMPPT techniques used in PSC, traditional MPPT techniques that cannot distinguish GMPP from local maximum power points have not been discussed.

CCTV cameras are extensively used for surveillance in areas that may need monitoring. CCTV footages serves an important key for investigation, as evidence in court. Nowadays, the CCTV manufacturers uses proprietary file system instead of the industry standard file system such as FAT16, FAT32, NTFS, HFS, Ext2 etc. The forensic analysis of proprietary DVR is a challenging task, as it uses a proprietary file system and not a standard one. The aim of this project is to analyze the File System of a proprietary DVR Hard Disk Drive of HIKVISION CCTV camera, a popular brand in market. This method involves reverse engineering the File System by reading and extracting CCTV videos and its metadata from the proprietary DVR Hard Disk Drive for the digital forensic investigation.

Heterodyne and direct detection radiometer receivers at 94 GHz have been realized in a 130 nm Si/SiGe BiCMOS process. They have been assembled into fully self-contained metal housings with a waveguide flange for the antenna connection. The receivers, which employ a SiGe LNA with below 4 dB noise figure, show overall responsivities of 620 µV/K and 380 µV/K respectively.

Traditional PC based operating systems load most of its components during the boot process along with the kernel. This mechanism though effective for a broader objective, is seldom utilized fully by a majority of users as they usually perform a specific job which does not require every component of OS. It has been observed that operating systems which are designed keeping in mind the nature of job, achieve better performance than standard systems even on an inferior hardware. Sony's PlayStation 4 gives better performance per watt when compared to a PC having similar graphics configuration. The prime cause of this weak performance is wasting of resources due to generic purpose OS design. This paper proposes a novel technique which will enable more efficient utilization of the hardware. Many choices are available to the user and each choice corresponds to a different mode of operation. This is achieved using modular shell design wherein the resource deployment is done according to the requirements of module. There is an uniform base module to allow easy and fast access to user allowing him to perform most basic tasks. Each module of the operating system shall be loaded to perform a specific task and will provide user with an enhanced access to perform a job. The user can switch among the modules according his requirements. This will also allow specific components in a kernel to allocate resources only according to the needs of the program. This mechanism will provide the benefits of real time OS in a time shared environment and will allow coordinated control of resources not possible in a traditional UNIX based operating system.

This thesis presents solutions and studies related to the design of reconfigurable and wideband receiver circuits for system-on-chip (SoC) radiometer front-ends within the millimetre-wave (mm-wave) range. Whereas many of today’s mm-wave front-ends are bulky and costly due to having discrete RF components, single-chip receiver modules could potentially result in a wider use for emerging applications such as wireless communication, short range radar and passive imaging security sensors if realised with adequate performances and at a lower cost. Three main topics are considered in this thesis, monolithic integration of low-loss RF-MEMS (Dicke) switch networks and switched LNAs in MMIC/RFIC foundry processes, designs of SiGe wideband (IF) amplifier and broadband power detectors up to W-band (75-110 GHz).Low-loss and high isolation GaAs and SiGe RF-MEMS switch networks were designed and characterised for the 30-110 GHz range. A GaAs MEMS Dicke switch network has a measured minimum loss of 1 dB and maximum isolation of 19 dB at 70-96 GHz, respectively, making it a potential candidate in Dicke switched radiometer receivers. Furthermore, single-chip 30 GHz and W-band MEMS Dicke switched LNA designs have been realised for the first time in SiGe BiCMOS and GaAs mHEMT processes, respectively.For a targeted 94 GHz passive imaging application two different receiver topologies have been investigated based on direct-detection and direct-conversion (heterodyne) architectures. An optimised detector design fabricated in a 0.13 μm SiGe process achieves a more wideband input matching than earlier silicon W-band detectors and is competitive with reported III-V W-band detectors in terms of a higher responsivity and similar NEP.A SiGe 2-37 GHz high-gain differential (IF) amplifier design achieves a more wideband matching and an order of magnitude higher linearity than a recent single-ended SiGe LNA. The SiGe IF amplifier was integrated on-chip with a power detector in a 5-35 GHz IF section. Their broadband properties compared with other IF amplifier/detector RFICs, make them suitable for W-band down-conversion receivers with a larger pre-detection bandwidth and improved sensitivity. The experimental results successfully demonstrate the feasibility of the SiGe 5-35 GHz IF section for high performance SoC W-band radiometers using a more wideband heterodyne receiver architecture.

This paper presents the results of some W-band power detector and wideband (IF) amplifier circuit designs made in 0.25 μm and 0.13 μm SiGe BiCMOS processes. Two 0.25 μm SiGe wideband power detector and amplifier RFICs present an NEP =1-2 pW/Hz1/2 at 85-101 GHz and s21=10-19 dB at 2-32 GHz, respectively. To the authors' knowledge, the proposed SiGe detector design reports the widest Sn bandwidth (s11≤ -10 dB 84-104 GHz) among SiGe based W-band detectors. Two 0.13 μm SiGe detector/amplifier circuits show a simulated NEP=0.2-0.9 pW/Hz1/2 at 75-100 GHz and S21= 19-21 dB at 5-30 GHz. The presented SiGe power detectors and (IF) amplifiers are targeting broadband applications such as passive imaging.

This paper presents the circuit designs and results of a wideband power detector and an on-chip slot antenna fabricated in a 0.25 μm SiGe BiCMOS process. The W-band SiGe detector has close to 20 GHz of operational bandwidth (s11≤−10 dB at 75–92 GHz) and a responsivity of 3–5kV/W (NEP = 10–16 pW/Hz1/2) at 83–94 GHz. The SiGe on-chip slot antenna design covers a wide bandwidth (70–110 GHz) with 2 dBi of simulated gain at 94 GHz. The realised wideband SiGe BiCMOS power detector and on-chip antenna are targeting highly integrated single-chip RF front-ends for broadband sensing applications up to 110GHz.

This paper presents mm-wave capacitive RF-MEMS based Single-Pole-Double-Throw (SPDT) switches fabricated in a SiGe BiCMOS process technology. Three different SiGe RF-MEMS based SPDTs (targeting the 40–80 GHz range) present 3–4 dB of in-band losses and up to 20–25 dB of isolation, respectively. The measured in-band attenuation of the characterized SiGe MEMS SPDTs corresponds to a loss of 2–3 dB when close to 1 dB of combined losses within the RF pads has been removed. The experimental s-parameter data was obtained from RF-tests of more than 300 characterized SPDT switch networks indicating a high fabrication yield and process repeatability of the fabricated SiGe MEMS circuits. The validated SiGe MEMS switch circuits can enable single-chip reconfigurable ICs for wireless communication and sensing applications up to 100 GHz.

We present an experimental study of some GaAs MMIC based RF-MEMS switch networks used here as limiter test circuits and that were tested also within a standard low-frequency package. The small and large signal results for such discrete as well as packaged GaAs MEMS limiter MMICs shows possibilities for obtaining a very wideband RF power limiter functionality within small circuit dimensions. Self switch actuation tests made on a packaged GaAs MEMS limiter circuit showed a power limiting effect of 11 dB for an RF input power of 16 dBm at 4 GHz.

This paper reports the design of an input--triggered polymorphic ASIC for H.264 baseline decoder.Hardware polymorphism is achieved by selectively reusing hardware resources at system and module level. Complete design is done using ESL design tools following a methodology that maintains consistency in testing and verification throughout the design flow. The proposed design can support frame sizes from QCIF to 1080p.

Support vector machines (SVM) have shown strong generalization ability in a number of application areas, including protein structure prediction. In this paper a new tertiary classifier is introduced that makes use of support vector machines as neurons in a neural network architecture. This network is optimized using genetic algorithms. The novel tertiary classifier is better than most available techniques.

This paper investigates the performance of different spreading factors for uplink WCDMA in frequency selective channels. Comparison of perfect channel knowledge with estimated channel is performed and analysed. The performance is also analyzed for different Doppler frequencies corresponding to different speeds. A conventional Rake receiver was developed whose performance improved with an increase in diversity and when the paths that arrived were separated by one chip duration. To estimate the channel parameters, that are needed to correct the phase rotations and attenuations caused by the fading channel, a Wiener filter was employed which produced estimates in agreement with the actual channel parameters. The performance of various spreading codes were analysed which showed that codes with higher spreading gain performed better than those with lower gains due to the high cross correlation between shorter code lengths. High intersymbol interference (ISI) was experienced by signals with high data rates (low spreading factors) than signals with low data rates. Performance of BER of signals experiencing higher Doppler frequencies were high than those with low Doppler frequencies