June 2011
Reducing the peak to average power ratio in OFDM systems
High peak to average power ratio of the transmit signal is a major drawback of OFDM systems. After defining the PAPR and analyzing its statistical properties, some of the most representative PAPR-reduction techniques available in the literature are reviewed in detail. Several methods have been proposed to reduce the peak power of...
June 2011
The idolization of Chien-Ming Wang and social psychological factors in Taiwan
This study aims to explore the relationship between the idolization of Chien-Ming Wang and the social psychological factors in Taiwan. Documentary analysis was applied to analyze the time and political background of baseball development in Taiwan. Also in-depth interviews with sports journalists in Taiwan, the CEO of the World Games 2009 in Kaohsiung, and Wang’s fans were conducted. It was found that Wang’s...
June 2011
Look ahead dynamic threshold voltage control for enhanced write margin of 45 NM 7T-SRAM cell
Instability of SRAM memory cells derived from aggressive technology scaling has recently been one of the most significant issues. Although a 7T–SRAM cell with an area tolerable separated read port improves read margins even at sub-1V, it unfortunately results in degradation of write margins. A new memory cell adopting a look ahead body-bias which dynamically controls the threshold voltage was proposed in...
June 2011
Frequency synthesis techniques for high speed communication system
The phase locked loop (PLL) has been widely used in wireless communication systems due to the high frequency resolution and the short locking time. In particular, it is possible to achieve a very high-frequency resolution together with fast settling and spectral purity. We used DDS and two types of PLLs analog as well as digital in our work. Though we gave a comparative results of PLLs used in our simulation based on...
June 2011
EE-RI-MAC: An energy-efficient receiver-initiated asynchronous duty cycle MAC protocol for dynamic traffic loads in wireless sensor networks
Introducing duty cycling in the MAC protocol used in wireless sensor networks has been proven to be an efficient way of prolonging the battery lifetime of the sensor nodes because idle listening is a high energy consumption factor. This concept has been proven efficient in the existing energy-efficient MAC protocols, including receiver-initiated MAC (RI-MAC). In this paper, we further enhance the RI-MAC protocol by...
June 2011
Power amplifier- memory-less non linear modeling
The power amplifier’s nonlinearity broadens the input signal’s bandwidth. This is known as spectral re-growth which is undesirable since it causes interference with adjacent channels. It also causes distortions within the signal bandwidth, which affects the bit error rate at the receiver. Most recent transmission schemes, such as wideband code division multiple access (WCDMA) or orthogonal frequency division...
June 2011
Extracting of tropospheric scintillation propagation data from Ku-Band satellite beacon
Satellite beacon measurements at 12.255 GHz with an elevation angle of 40.1° during concurrent rain attenuation and tropospheric scintillation are analyzed. The power spectra density of the beacon signal is presented and scintillation are extracted from the raw propagation beacon data using a high pass filter with a cutoff frequency ranging from 2 to 500 mHz. It was observed at low frequency (2 mHz) the presence of...
June 2011
Study on corollary of seismic base isolation system on buildings with soft storey
Soft storey buildings are characterized by having a storey which has a lot of open spaces. This soft storey creates a major weak point in an earthquake. Since soft stories are classically associated with retail spaces and parking garages, they are often on the lower stories of a building, which means that when they collapse, they can take the whole building down with them, causing serious structural damage which may...
June 2011
Seismic risk analysis of Denizli (Southwest Turkey) region using different statistical models
Risk analyses made in an area of seismic activity are of great importance in determining earthquake occurrence intervals and recurrence periods. Several methods, some of which include statistical methods, have been developed for this purpose. Gamma, Weibull distributions and Markov, Poisson, Gumbel are the most frequently used methods in this regard. In this study, instrumental records of 73 earthquakes of...
June 2011
Effect of time elapse after wave hitting on coupled Spar platform
Oil and gas exploration has moved from shallow to much deeper water now-a-days. Offshore compliant floating structure like Spar platforms in this region are competent deep water platform. As water depth increase operational Spar platforms experience more influence of mooring lines suggestively. So the motion analysis of platforms in deep waters requires counting the mooring upshot with spar hull. The most common...
June 2011
Vibration and stability of multi-cracked beams under compressive axial loading
In this study, a novel technique for the vibration and stability analyses of axially loaded beams with multi-cracks was offered. In the model which combines the finite element and component mode synthesis methods, the cracks were modelled as massless springs. Initially, stability analysis was completed and then three numerical cases were given to explore the effects of axial load levels, crack locations and ratios on...
June 2011
A visual inspection system for quality control of optical lenses
This paper proposes a quality inspection system for optical lenses using computer vision techniques. The system is able to inspect LED (Light-Emitting Diode) lenses visually and to validate their quality level automatically based on the defect severity. The optical inspection system applies the block discrete cosine transform (BDCT), Hotelling statistic, and grey clustering technique to detect visual defects...
June 2011
A cross-layer scheme for resource reservation based on multi-protocol label switching over mobile IP version6
The last decades have brought tremendous improvement in wireless internet and its technologies. This has inspired the development of a variety of new services in business and consumer markets. The real time applications such as voice over internet protocol (VOIP) and other multimedia traffic such as Internet Protocol television have driven the demand for increasing and guaranteed bandwidth requirements in the network....
June 2011
An approach for crosscutting concern identification at requirements level using NLP
Poor requirements analysis process results in incomplete software applications. Some requirements appear as scattered and tangled concerns within requirements document. Hence it is difficult to identify such requirements. A number of research approaches such as Theme/Doc, early aspects identification, information retrieval and aspects identification using UML have been developed to identify crosscutting concern at the...
June 2011
Production of polyurethane/nano-hydroxyapatite hybrid materials and microstructural characterization
In the present work, the polyurethane/nanohydroxyapatite hybrid materials were prepared with different content of nHA (0, 10, 20, 30, and 40% weight) as filler. The nanohydroxyapatite powders were synthesized by hydrothermal synthesis and by ultrasound-assisted co-precipitation methods. The synthesis of polyurethane was carried out by a two-step polymerization method using 1,6-diisocyanate hexane, polycaprolactone and...
June 2011
X-ray photoelectron spectroscopy and atomic force microscopy studies on crosslinked chitosan thin film
Crosslinked chitosan solution was synthesized by homogeneous reaction of medium molecular weight chitosan in aqueous acetic acid solution with glutaraldehyde as crosslinking agent. The solution was then deposited on glass cover slip by spin coating to form thin film. The crosslinked chitosan thin film had been studied by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The XPS data was obtained...
June 2011
Intelligent routing information protocol using full triggered update mechanism
The heartbeat of network is the routing services which are available upon the execution of protocols. Many routing protocols emerge over one another to strive for betterment in performing the main function of routing the packets to destination efficiently. Despite the superiority of the new protocols in certain feature, the old routing information protocol (RIP) is still widely used due to its simplicity. RIP updates...
June 2011
Input-to-state stable (ISS) and exponential chaotic lag synchronization
In this paper, the lag synchronization problem is considered for chaotic dynamical systems with external disturbance via input-to-state stability (ISS). A sufficient condition for determining the lag synchronization between the drive and corresponding response systems is derived based on Lyapunov theory. The proposed ISS lag synchronization controller guarantees the exponential lag synchronization and achieves the...
June 2011
Pre-service physics teachers’ comprehension of wave function and operator concepts in quantum mechanics
This qualitative study investigates students’ comprehension of wave function and operator concepts. The data of the study were collected by semi-structured interviews with 34 pre-service physics teachers and analyzed by using the content analysis method. As a result of qualitative analysis, different categories were determined towards the students’ comprehension of wave function and operator concepts. ...
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