Shanthi Prince

A novel methodology for brain tumor detection based on two stage segmentation of MRI images

Medical imaging modalities like Magnetic Resonance Imaging, Computed Tomography, Positron emission tomography are complex modalities. It contains different objects like soft tissues and bony structures along with the noise included during the process of image acquisition. Segmentation of these images is a challenging task, as we need to separate the different objects and noise to get better diagnostic results. This paper presents a novel methodology of two stage segmentation. In the first stage, we apply Gabor filter banks generated using different frequencies and orientations. In the filtered image Region Of Interest (ROI) is identified and iterative contour detection method is applied to the filtered image, which detects different objects in the image. Segmentation is achieved using discrete gray level sets. Tumor region is extracted using threshold segmentation and it is analyzed for shape and size. The simulation results obtained are very promising for the detection and analysis of the brain tumor.

Performance analysis and optimization of radio over fiber link

This paper is an attempt for a thorough appraisal of Radio over Fiber (RoF) systems. RoF system is divided into three main subsystems: Central Station (CS), Optical Fiber Network (OFN) and Base Station (BS). Each subsystem has its own functions, such as signal generation and modulation techniques at the central station, optical fiber characteristics and the detection at the base station. In this paper the merits of RoF systems have acknowledged. The radio frequency and optical modulation techniques, fiber characteristics and detection techniques are studied. The impact of technology choice is reviewed and comparison of optical modulation techniques, optical fiber and receiver are presented. There has been a significant efforts dedicated to the merging of radio frequency and optical fiber technologies targeting the distribution of radio wave signals, in the recent years. The domain of Radio over Fiber (RoF) technologies and systems took birth from these endeavors. This kind of systems promises a secure, cost-effective, and high-capacity mobile and wireless access for the prospect facilitation of broadband, interactive, and multimedia wireless services.

System analysis for optimizing various parameters to mitigate the effects of satellite vibration on inter-satellite optical wireless communication

Inter-satellite links are necessary between satellites in orbits around the earth for data transmission between satellites and also for efficient data relay from one satellite to other and then to ground stations. Inter-satellite Optical Wireless Communication deals with the use of wireless optical communication using lasers instead of conventional radio and microwave systems. Optical communication using lasers provide many advantages over conventional radio frequency systems. A major problem existing in this wireless optical communication for inter-satellite links is the effects of satellite vibration, which results in serious pointing errors that degrade the performance. Performance of this system also depends on various parameters like transmitted power, data rate and antenna aperture which are analyzed using OptiSystem simulation software. This paper suggests ways to tackle effects of satellite vibration by optimizing the parameters of system design. The results of this study could be used further to design a feedback loop to correct effects of satellite vibrations in the system.

Design of full adder and subtractor based on MZI — SOA

A systematic model for all-optical full adder as well as full subtractor is proposed based on principle of Mach Zehnder Interferometer and using Semiconductor Optical Amplifier (MZI-SOA) configuration. MZI plays a role for ultra fast all-optical signal processing, here the non-linear property of SOA are properly utilized for designing the full adder as well as full subtractor. In this model the full adder as well as full subtractor can be effectively designed by properly selecting output terminals of MZI-SOA component. The design is implemented with the help of OptiSystem software which is one of the powerful software for analyzing Optical components. The proposed mode shows design performance of full adder as well as full subtractor in optical domain and it seems to be future wireless technology.

Designing issues in design of underwater wireless optical communication system

In designing the underwater optical wireless system, there are many issues that are to be considered. Since water channel is highly attenuating for Ultrasound and RF, optical signal is a suitable candidate. However, the choice of wavelength depends on the water characteristics. Moreover in designing the optical transmitter system the modulation scheme that can perform better is to be studied. This paper presents the performance of optical wireless communication system based on the water type, wavelength choice, photon detector sensitivity and modulation technique and enable one to design an optimum underwater wireless optical communication system. In particular, we contrast the performances of On-Off keying, Pulse Position Modulation and Differential PPM, when a PIN and avalanche photodiode is used at the receiver for different water types.

Underwater communication system for deep sea divers using visible light

This paper discusses a novel idea for transmission of voices in real time, underwater so that the system can be used by the deep sea divers for both lightning and data transfer applications simultaneously. Experiments were performed using white light, green and blue light respectively to transfer voice in real time in a water tank and the graphs were obtained. Based on the comparison study, we make recommendations for the selection of the right colour of light for communication efficiency in specified underwater environments.

Analysis of diffuse reflectance spectra of various skin conditions by principal component method

Different skin and sub-surface tissues have distinct or unique reflectance pattern which help us differentiate normal and cancerous tissues. Optical means of characterizing tissues have gained importance due to its noninvasive nature. Spectral characteristics of the components provide useful information to identify the components, because different chromophores have different spectroscopic responses to electromagnetic waves of a certain energy band.

Functional Optical Imaging of a tissue based on Diffuse Reflectance with Fibre Spectrometer

The functional state of tissue can influence its optical properties. Functional optical imaging capitalizes on the changing optical properties of tissue by using light to measure physiological changes. Optical Imaging i.e., medical imaging with light radiation is gaining importance especially for early detection of cancer.

An automated system for optical imaging to characterize tissue based on diffuse reflectance spectroscopy

More interest is shown towards optical technologies that have the capability of performing in situ tissue diagnosis without the need for tissue biopsy. The ability to non-invasively detect early disease is a boon to the patients as well as the medical professionals. In actuality, detection at the fully formed but not spreading stage is acceptable. We must see lesions as they are transforming from a pre-cancerous state to a cancerous state, to be successful at very early detection. Early diagnosis is of paramount importance to manage precancerous and malignant lesions. Discrimination between normal-tissue and new tissue formation relies on morphological and functional pattern recognition. The functional state of tissue can influence its optical properties. Functional optical imaging capitalizes on the changing optical properties of tissue by using light to measure physiological changes. The basis for this imaging method arise from the differences in the spectra obtained from the normal and diseased tissue owing to the multiple physiological changes associated with increased vasculature, cellularity, oxygen consumption and edema in tumour. An optical fiber spectrometer is set up for this purpose, which is safe, portable and very affordable relative to other imaging modalities. The method involves exposure of skin surface to white light produced by an incandescent source. The back scattered photons emerging from various layers of tissue are detected by spectrometer resulting in tissue surface emission profile. Initially, the study is conducted on tissue equivalent phantoms The spectral data from the scan is processed using a suitable algorithm to form an image which can directly assist us in differentiating the part which is affected by disease visually. The unique information obtained from the diffuse optical spectroscopy makes it suitable for a variety of clinical applications, such as therapeutic monitoring, lesion characterization and risk assessment.

Implementation of a reversible all optical multiplexer using Mach-Zehnder interferometer

With the advancements in technology, the main factor which plays a crucial role in designing any circuit is power. Low power design has been the term being used by most of the researchers. Reversible logic is one of the solution which can be used to make the designs consume less power. Reversible logic circuits are also the basic building blocks of a quantum computer which will be a reality in the coming years. In recent years all optical computing has seen an increasing trend among researchers and will be useful in next generation computing. Reversible logic circuits in optical domain will play a major role in designing a power efficient optical network. Implementation of reversible logic circuits in optical domain can be carried out by using Semiconductor optical amplifier (SOA) based Mach-Zehnder Interferometer (MZI) because of its features like high speed, fast switching time and ease of fabrication. In this paper the implementation of a reversible 2 × 1 multiplexer in all optical domain is described with its analysis in terms of optical cost and delay.