Advanced Materials Research Vols. 403-408

Abstract: The development of satellite communication technology has brought the Vehicle tracking systems to the day-to-day life of the common man. Today GPS fitted cars, ambulances, fleets and police vehicles are common on the roads. All the existing technology can support only tracking the vehicle place and status. No such systems have implemented emergency alert during accidents, using smart phone. Real time vehicular tracking system incorporates a hardware device installed in the vehicle and a remote Tracking server. The information is transmitted to Tracking server using GSM/GPRS modem on GSM network by using SMS or using direct TCP/IP connection with Tracking server through GPRS. Tracking server also has GSM/GPRS modem that receives vehicle location information via GSM network and stores all this information in computer database. This information is available to authorized users of the system via website over the internet.The embedded device fitted with “sensors”. The sensors used are to provide Automated Emergency Alert in case of accident (Inform nearby Police, Hospital and Owner through SMS), Identification of Halts and Duration, Emergency Message Display in Centralized computer, Automatic update of Emergency number, Fuel Tank Pilferage Monitoring and Distance and Speed computation. The data from the sensors are transferred to centralized server through GSM enabled device. GPS device is used to track the vehicle locations in latitude and longitude. The GPS device is received raw satellites data in this data is not understandable first we convert raw data to digital form and transmitted to centralize computer. Each licence vehicle owner can access the data using web service and can retrieve all the real time data and stored previous data in database. Because whole Proposed system control in a single chip so proposed system allows for the stability, equilibrium, less resource use and sustainability of a tracking system and save of the people life.

Abstract: Leakage Current is found to be gradually increasing in CMOS VLSI circuits with advance of technologies, specially in nanometer range. Though area of a transistor is becoming less and lesser, but precious control over the operations of a transistor is not possible in such a small structure. Reductions of threshold voltage, channel length, and gate oxide thickness are responsible for generation of leakage current. In this paper we have reviewed eight types of leakage current present in CMOS VLSI circuits, namely 1. Reverse Bias pn Junction Current, 2. Sub-threshold Leakage, 3. Drain Induced Barrier Lowering Effect, 4. Gate Induced Drain Leakage current, 5. Punch Through, 6. Narrow Channel Effects, 7. Gate Oxide Tunneling leakage current and 8. Hot-Carrier Injection. After that, we have reviewed 6-T SRAM read and write operation. Next to that, we have reviewed three techniques of leakage reduction namely 1. Transistor Stacking Effect, 2. Data Retention Gated-Ground Cache and 3. Drowsy Cache. We have reproduced the simulation result of these leakage minimization techniques. Finally we have shown comparison of 1. Conventional 6-T SRAM leakage current, 2. leakage current using Data Retention Gated-Ground Cache techniques and 3. leakage current using Drowsy Cache techniques. To obtain these three results we have used Cadence Virtuso & SoC Encounter tools. All these three results has been simulated with IBM 90 nanometer technology file.

Abstract: We present a detailed fabrication process of silicon optical waveguide with a depth of 4μm via simulation and experiment. An anisotropic wet etching using Potassium Hydroxide (KOH) solutions was selected to study the influence of major fabrication parameters such as etch rate, oxidation time and development time to the fabrication performance. The fabrication of the silicon waveguide with the orientation of was modeled using ATHENA from 2D Silvaco software and was later compared with the actual fabricated device. Etching time of 4 minutes was required to etch the Si to the depth of 4μm to obtain a perfectly trapeizoidal optical waveguide structure. Our results show that the simulation model is trustworthy to predict the performance of the practical anisotropic wet etching fabrication process. The silicon-based waveguide components are targeted to be employed in realizing future photonic devices such as optical modulators.

Abstract: We proposed the formation of well potential of bright solitary wave in fiber Bragg grating. The study has been successfully performed out under Bragg resonance condition where the initial frequency of the light has the same value with the Bragg frequency. The Stokes parameter provides important information on the total energy and energy differences between the forward and backward propagating modes. The nonlinear parameter in this study was initially set to α = 1.0 and -1.0, β = 0.7 and γ = 0.1.

Abstract: In bulk heterojunction solar cells, the donor and acceptor materials are intimately blended throughout the bulk, so that the excitons generated will reach the interface within their lifetime. In this work, Rosebengal (RB) is used as the donor material and nanocrystalline Titanium dioxide (nc TiO₂) as the acceptor material. Devices with device structure ITO/RB:TiO₂/Ag are prepared and their optical and electrical properties are compared at different temperatures. Optical absorption spectroscopic analysis shows that the absorption of Rose bengal ranges from 650-800 nm corresponding to a band gap of 1.98 eV. Cyclic voltametric analysis, and photo voltaic properties are analysed. Using simulation, the dark current parameters such as ideality factor (n), mobility (µ) potential barrier (φ_b) and carrier concentration are extracted and tabulated.

Abstract: This paper proposed an efficient spatial Access method, called MDR-Tree (Mbr compression and Delayed write operation based R-Tree), that uses the node compression technique and the delayed write operation technique for flash memory embedded systems. The node compression technique of MDR-Tree increased the utilization of flash memory space by compressing the MBR of spatial data using relative coordinates and MBR size. Moreover, the delayed write operation technique reduced the number of write operations in flash memory by temporarily storing spatial data in the buffer and by reflecting them in flash memory at once instead of reflecting the insert, update and delete of spatial data in flash memory for each operation. Especially, the utilization of buffer space was enhanced by preventing the redundant storage of the same spatial data in the buffer.

Abstract: Removed at authors request.

Abstract: Atomic vapor cell is the most important component for atomic clock. A few vapor cells were fabricated based on multi-stack anodic bonding with four fabrication methods. By comparing with three traditional cavity fabrication methods and the first failed method by the laser drilling, it was found that the surface contamination induced in laser drilling and the roughness blocked the successful bonding. The surface roughness has to be less than 8 nm and in this case the method of laser drilling can be used successfully and with high efficiency, resulting in a novel process for atomic vapor cell fabrication with cavity.

Abstract: The optical properties is essential to the process of identification in Laser Identification Friend or Foe (Laser-IFF) system. The corner cube reflector (CCR), composed of three mutually orthogonal reflective micromirrors, is extensively used in Laser-IFF system for it can reflect incident light at any angle to its incoming direction. So the micromachined CCR array is set to be the most important component of the responder. And assuming the Laser-IFF system is used in missiles, we present an analysis of the optical properties about the responder sectional area, the signal power of the responder and the echo power from the responder to the inquirer, considering at different effect distances between the inquirer and responder, divergence half-angle, CCR arrays reflectivity and other factors. Further field testing about the system can reference obtained experimental results and conclusions.

Abstract: Optical microcavities confine light to small model volumes and have ultrahigh quality factor (Q), especially microtoroid cavities, having very broad application prospects. In this paper, we use MEMS (Microelectromechanical System) skills, such as lithography, dry etching to fabricated silica optical microdisks. And after that, a novel processing method based on CO₂ laser reflow technology is introduced to create microtoroid cavities. The processing details are discussed including light path, laser power and other important parameters. The quality factor of the planar microtoroid cavity was measured by taper-fiber coupling and the average value reach 4.8×10⁵.