Towards Faster Spectrum Sensing Techniques in Cognitive Radio Architectures

AbstractIn the recent years, the subject of spectrum sensing techniques has been well studied in research community, highly motivated by the emergence of cognitive radio architectures. But in practice, given the complexity of proposed spectrum sensing techniques, the implementation of cognitive radio has become a tedious task. Unlike many papers in the literature, this paper focuses on implementation aspects of spectrum sensing. Especially, we attempt to reduce the time taken for spectrum sensing based on adaptive FFT approach employing statistical analysis. The first step of the many spectrum techniques is to obtain the FFT of input samples. Most of the existing spectrum analyzers like Tektronix RSA6000, Rohde & Schwarz FSVR etc employ detection and estimations algorithms based on the FFTs of the acquired samples. In this paper, we propose an algorithm to vary the FFT-size to obtain the spectrum information at a faster rate, applicable to cognitive radio environment. FFT size would be varied in accordance with statistical information obtained from the prediction engines. The proposed Adaptive FFT algorithm is studied as applied to the well known energy detection technique. Finally an implementation is carried out on USRP based on GNU Radio platform

Capsaicin and TRPV1 Channels in the Cardiovascular System: The Role of Inflammation

Capsaicin is a potent agonist of the Transient Receptor Potential Vanilloid type 1 (TRPV1) channel and is a common component found in the fruits of the genus Capsicum plants, which have been known to humanity and consumed in food for approximately 7000–9000 years. The fruits of Capsicum plants, such as chili pepper, have been long recognized for their high nutritional value. Additionally, capsaicin itself has been proposed to exhibit vasodilatory, antimicrobial, anti-cancer, and antinociceptive properties. However, a growing body of evidence reveals a vasoconstrictory potential of capsaicin acting via the vascular TRPV1 channel and suggests that unnecessary high consumption of capsaicin may cause severe consequences, including vasospasm and myocardial infarction in people with underlying inflammatory conditions. This review focuses on vascular TRPV1 channels that are endogenously expressed in both vascular smooth muscle and endothelial cells and emphasizes the role of inflammation in sensitizing the TRPV1 channel to capsaicin activation. Tilting the balance between the beneficial vasodilatory action of capsaicin and its unwanted vasoconstrictive effects may precipitate adverse outcomes such as vasospasm and myocardial infarction, especially in the presence of proinflammatory mediators

Process Modeling, Monitoring and Control of Laser Metal Forming 235

Laser Metal Forming (LMF) process is one of the prominent Rapid Prototyping (RP) process that can be used to develop functional and fully dense metal parts. This paper addresses process modeling, monitoring and control of a laser metal forming system currently under development at Laser Aided Manufacturing Processes (LAMP) laboratory at University of Missouri–Rolla. This LMF system is based on a 2.5kW Nd:YAG laser as energy source and integrates five axis metal deposition and five axis machining. The current paper is aimed at characterization of effects of operating parameters such as traverse speed, mass flow-rate and laser power on the LMF process. A low cost monitoring system is being developed using off the shelf sensors like infrared temperature sensor, near infrared CCD camera and laser displacement sensor to measure the process index parameters. A closed loop control structure has been simulated for online control of the LMF process.This research was supported by the National Science Foundation Grant Number DMI-9871185, Missouri Research Board, and a grant from the Missouri Department of Economic Development through the MRTC grantMechanical Engineerin

Postpartum eclampsia of late onset

Pre-eclampsia and eclampsia occur in 6% to 8% of all pregnancies.1 The British eclampsia study confirmed 383 cases of eclampsia during 1992 and warned of the severe consequences of the condition.2 In 1997 Leitch and colleagues showed that over a 60 year period the incidence of eclampsia had fallen from 74/10 000 to 7.4/10 000, although the incidence of postpartum eclampsia had increased.3 A US study identified 229 cases of postpartum preeclampsia or eclampsia between 1992 and 20024; 151 of these cases were diagnosed after readmission to hospital with new symptoms and signs after delivery, and 16% (24/151) of these had eclampsia. Other work from the United States identified 89 cases of eclampsia during 1996 to 20015; 29 cases (33%) presented in the postpartum period. In both these US studies most cases developed symptoms more than 48 hours post partum