Bhanu Shrestha

An Energy-Efficient Cluster-Based Routing in Wireless Sensor Networks

In Wireless Sensor Networks (WSNs), sensor nodes depend on batteries for energy source. The ability to use limited energy efficiently is the key to determining the lifetime of networks and the amount of information transmitted. Low Energy Adaptive Clustering Hierarchy (LEACH) is a representative cluster-based routing protocol designed to ensure energy use efficiency. In this paper, a protocol scheme was proposed wherein member nodes (lower-level nodes) are designed to compare the currently sensed data with the previously sensed one and to switch to sleep mode when a match is achieved. The design is to help improve the transmission energy efficiency. The proposed scheme was tested via simulations and was compared with two existing cluster-based algorithms, i.e., LEACH and Threshold Sensitive Energy Efficient Sensor Network Protocol (TEEN). Performance evaluation was conducted based on the number of surviving nodes in each of the three networks (i.e., LEACH, TEEN, and proposed scheme) over time. The results indicated that the scheme contributed to greater energy efficiency by helping to increase the lifetime of the LEACH network by a maximum of 27%.

High performance integrated passive technology by SI-GaAs-based fabrication for RF and microwave applications

Conclusions IPD technology is paramount in furthering the performance and integration of functionality as well as shrinking in size in RF front-end systems. The proposed fabrication process enables a high performance integration of passive technology; the reliable NiCr TFR, spiral inductor with high Q factor, and MIM capacitor of compact size with high yield are realized by the IPD technology, and Wilkinson power divider is fabricated with excellent RF performances.

Energy Efficient Routing in Wireless Sensor Networks

Sensor nodes depend on batteries for energy source in Wireless Sensor Networks (WSNs). Low Energy Adaptive Clustering Hierarchy (LEACH) is a representative cluster-based routing protocol designed to ensure energy use efficiency whereas the virtual cluster exchange routing (VCR) information only with its closest node to build a network. In this paper, a protocol scheme was proposed wherein member nodes are designed to compare the currently sensed data with the previously sensed one and to switch to sleep mode when a match is achieved. The design is to help improve the transmission energy efficiency too.

English course E-learning system based on relative item difficulty using web component composition

Many researches about e-learning system have been applied item difficulty to increase learning effectiveness. And development environment was changed the internet based learning media contents into the more various technology such as component, web 2.0, service oriented development and so on. Especially, service-oriented development is one of new trend in web based system and has become mainstream in software development. In the development, web components aims at providing support to service-oriented technique by enabling automatic discovery, composition, invocation and interoperation of the services. In this paper, we aimed the implementation of English e-learning system including the item guessing parameter and considering the relative correction of item difficulty. In the system, a learner was given to choose the learning step by the relative difficulty. In order to process and combine, all the learning contents are based on Sharable Content Object Reference Model (SCORM) with Learning Management System (LMS). Also, each learning contents are belong to Sharable Content Objects (SCOs).

Double Cross Coupled Colpitts VCO with Low Phase Noise using InGaP/GaAs HBT Technology

The proposed double cross-coupled differential Colpitts voltage controlled oscillator (VCO) is designed using InGaP/GaAs HBT technology for an adaptive feedback interference cancellation system (AF-ICS). In this paper, two switching transistors were used to steer the bias current and voltage in the VCO core, thereby saving power. The VCO achieves excellent phase noise characteristics of -135 dBc/Hz at 1 MHz offset from carrier frequency (1.630 GHz) when supplied with a control voltage of 0 V Also, its tuning range is around 218 MHz with an output power of -3.91 dBm (including cable loss). It shows the figure of merit (FoM) of -180.5 dBc/Hz. Two pairs of base-collector (BC) diodes are integrated in the tank circuit to increase the VCO tuning range. The optimized chip size is 0.9 mm x 0.9 mm.

A Novel Harmonic Noise Frequency Filtering VCO for Optimizing Phase Noise

InGaP/GaAs HBT LC-VCOs designed with and without the proposed harmonic noise frequency filtering (HNFF) technique are presented here. To optimize phase noise, the HNFF technique is compared using noise frequency filtering capacitors. The HNFF-VCO produced ultra low phase noise performance. The tuning range of this VCO is 261 MHz with an output power of -10.25 dBm at 1.721 GHz carrier. Furthermore, the phase noise of this VCO -133.96 dBc/Hz at 1 MHz offset. The HNFF-VCO is designed with a total chip area of 0.9 - 0.9 mm2. Its phase noise performance is enhanced by 8.9 dBc at 1 MHz offset by comparison with a N-VCO without the HNFF technique

Study of Generating Animated Character Using the Face Pattern Recognition

The similar character of input video image can be generated by combining each components points after extracting the position of each component points using the ratio of face. By selecting the face area, in case of the upper half image, the neck and stained hair become change and accuracy of recognition of selected area becomes low, so in order to compensate the area of inaccuracy, we can find the shape of face, eyes and mouth applying the golden ratio and the character is reflected in the results. Using color informations of the image of the face, the TSL color can be analysed and shown the face recognition ratio of 1.7%. The components in each five input images (left and right eyes, eyebrows and mouth) by selecting the test results showed the performance of 88.3%. By analyzing the characteristics of the elements found in those features automatically generate the appropriate characters, and the rabbit character can be automatically generated from the animation story of ‘Rabbit and Tortoise’ made by flash tool. Using the TSL color model, the face shape and the eyes, eyebrow, nose, mouth, and ears are visualised in a 2D. In the digital cultural content, the character is automatically generated by video input image and oneself can be staged as a hero in the animation which is the development of a new digital cultural contents.

A high-power Ka-band power amplifier design based on GaAs P-HEMT technology for VSAT ODU applications

In this paper, a Ka-band GaAs pseudomorphic high electron mobility transistor (P-HEMT) monolithic microwave integrated circuit (MMIC) power amplifier for very small aperture terminal (VSAT) outdoor unit (ODU) transmitter applications in demonstrated. This three-stage power amplifier is designed to fully match the 50 Ω input and output impedances. With 6 V and −0.75 V DC bias, a small signal gain of 11 dB, a 1 dB compression power (P1dB) of 29.5 dBm, a power added efficiency (PAE) of 31%, and a better than −15 dB input return loss are achieved from 28.5 to 31.5 GHz. The proposed Ka-band power amplifier is designed within a die size of about 3.344 × 1.964 mm2 on GaAS substrate.

Analysis of Two Filtering Techniques in Differential LC VCO Design using Asymmetric Tank Structure

Abstract This paper presents two InGaP/GaAs HBT (heterojunction bipolar transistor) differential cross-coupled voltage controlled oscillators (VCO) designed with low phase noise for adaptive feedback–interference cancellation systems (AF-ICS). The main idea is to use low pass and band pass Altering technique for noise frequency. With this, the designed VCO, the first one achieved a phase noise of −130.40 dBc/Hz at 1 MHz offsets from the carrier frequency of 1.619 GHz and the second one achieved −127.93 dBc/Hz at 1 MHz offsets from the carrier frequency of 1.604 GHz. Each VCO dissipates an output power of −6.68 dBm and −10 dBm respectively by supplying 5 V. Two pairs of base-collector (BC) junction diode are used as varactor to get a broad band tuning range for both VCOs.

Design of Diodes Feedback Differential Colpitts Voltage Controlled Oscillator with Low Phase Noise Based on InGaP/GaAs HBT Technology

Abstract The proposed differential Colpitts VCO (voltage controlled oscillator) is based on on-chip base collector (BC) diodes feedback in InGaP/GaAs HBT for interference cancellation system (AF-ICS) application. The VCO achieved significant low phase noise characteristics of −131.04 dBc/Hz at 1 MHz offset from the carrier frequency of 1.540 GHz, at a bias current of 15 mA and voltage of 5 V. It dissipates output power of −11.26 dBm when supplying the control voltage of 1.9 V. A tuning range of 141 MHz is achieved using integrated tuning BC diodes. This VCO shows a figure of merits (FoM) of −183 dBc/Hz, at the desired frequency. A chip size is optimized to 0.816 × 0.871 mm2.