From Spectrum Pooling to Space Pooling: Opportunistic Interference Alignment in MIMO Cognitive Networks

We describe a non-cooperative interference alignment (IA) technique which allows an opportunistic multiple input multiple output (MIMO) link (secondary) to harmlessly coexist with another MIMO link (primary) in the same frequency band. Assuming perfect channel knowledge at the primary receiver and transmitter, capacity is achieved by transmiting along the spatial directions (SD) associated with the singular values of its channel matrix using a water-filling power allocation (PA) scheme. Often, power limitations lead the primary transmitter to leave some of its SD unused. Here, it is shown that the opportunistic link can transmit its own data if it is possible to align the interference produced on the primary link with such unused SDs. We provide both a processing scheme to perform IA and a PA scheme which maximizes the transmission rate of the opportunistic link. The asymptotes of the achievable transmission rates of the opportunistic link are obtained in the regime of large numbers of antennas. Using this result, it is shown that depending on the signal-to-noise ratio and the number of transmit and receive antennas of the primary and opportunistic links, both systems can achieve transmission rates of the same order.Comment: Submitted to IEEE Trans. in Signal Processing. Revised on 23-11-0

Power Allocation and Cooperative Diversity in Two-Way Non-Regenerative Cognitive Radio Networks

In this paper, we investigate the performance of a dual-hop block fading cognitive radio network with underlay spectrum sharing over independent but not necessarily identically distributed (i.n.i.d.) Nakagami-$m$ fading channels. The primary network consists of a source and a destination. Depending on whether the secondary network which consists of two source nodes have a single relay for cooperation or multiple relays thereby employs opportunistic relay selection for cooperation and whether the two source nodes suffer from the primary users' (PU) interference, two cases are considered in this paper, which are referred to as Scenario (a) and Scenario (b), respectively. For the considered underlay spectrum sharing, the transmit power constraint of the proposed system is adjusted by interference limit on the primary network and the interference imposed by primary user (PU). The developed new analysis obtains new analytical results for the outage capacity (OC) and average symbol error probability (ASEP). In particular, for Scenario (a), tight lower bounds on the OC and ASEP of the secondary network are derived in closed-form. In addition, a closed from expression for the end-to-end OC of Scenario (a) is achieved. With regards to Scenario (b), a tight lower bound on the OC of the secondary network is derived in closed-form. All analytical results are corroborated using Monte Carlo simulation method

Private Decayed Sum Estimation under Continual Observation

In monitoring applications, recent data is more important than distant data. How does this affect privacy of data analysis? We study a general class of data analyses - computing predicate sums - with privacy. Formally, we study the problem of estimating predicate sums {\em privately}, for sliding windows (and other well-known decay models of data, i.e. exponential and polynomial decay). We extend the recently proposed continual privacy model of Dwork et al. We present algorithms for decayed sum which are \eps-differentially private, and are accurate. For window and exponential decay sums, our algorithms are accurate up to additive 1/\eps and polylog terms in the range of the computed function; for polynomial decay sums which are technically more challenging because partial solutions do not compose easily, our algorithms incur additional relative error. Further, we show lower bounds, tight within polylog factors and tight with respect to the dependence on the probability of error

Design and Implementation of Photovoltaic Maximum Power Point Tracking Controller

تعتمد الطاقة التي توفرها أي منظومة شمسية على الظروف البيئية كأحوال الطقس (درجة الحرارة وكثافة الإشعاع) وزاوية السقوط من مصدر الإشعاع. يهدف العمل لدراسة الحد الأقصى للمخططات التي يمكن أن تستخدم لمقارنة أداء النظام بدون ومع المسيطرات المختلفة. الأول المتحكم النسبي التكاملي – التفاضلي النوع والثاني المتحكم الاضطرابي والتلاحظي. نظام التحويل يرتبط بمتحكم دقيق. حيث تم دراسة ومقارنة نتائج نقطة الطاقة القصوى للوحة الطاقة الشمسية تحت الاختبار مع نوعين من المسيطرات المختلفة وتمت مقارنة نتائج الاختبارات التجريبية مع نتائج المحاكاة للتحقق من دقة الأداء . The power supplied by any solar array depends upon the environmental conditions as weather conditions (temperature and radiation intensity) and the incident angle of the radiant source. The work aims to study the maximum power tracking schemes that used to compare the system performance without and with different types of controllers. The maximum power points of the solar panel under test studied and compared with two controller's types.  The first controller is the proportional- integral - derivative controller type and the second is the perturbation and observation algorithm controller. The associated converter system is a microcontroller based type, whereas the results studied and compared of greatest power point of the Photovoltaic panels under the different two controllers. The experimental tests results compared with simulation results to verify accurate performance

A Study of Z-Transform Based Encryption Algorithm

It has become increasingly important to ensure the protection of information, especially data in transit. Therefore, it is the primary goal of any encryption algorithm to safeguard the protection of information against security attacks. It is equally important to design high-performance solutions with affordable cost of implementation. Encryption algorithms are used to transform plain text to the ciphertext in order to protect privacy, prevent data fraud, and prevent unauthorized access of data in daily transactions. There are multiple types of encryption algorithms, each with its niche tactics to enhance security. For instance, different kinds of algorithms include but are not limited to the following: Blowfish, RSA, AES, DES, Triple DES. This paper contributes an efficient and secure encryption algorithm technique for information security based on Z transformation and XOR function known as the Z Transformation Encryption (ZTE) technique. To elaborate, this technique implements concepts of Z transformation and XOR operations at the source. The reverse process is applied at the receiving end of the transaction wherein the inverse of Z transformation and XOR is applied to reveal the original plain text message. The simulation of the proposed algorithm is conducted using the R language. The results show a promising performance comparing to other symmetric algorithms

Effects of ankle angular position and standing surface on postural control of upright stance

The purpose of the study was to investigate the effects of ankle angular position and standing surface type on static upright balance. Ten young adults stood on a force platform or on a firm wedge that induced 15° of either dorsiflexion or plantarflexion. In addition, a piece of foam was placed on top of the force platform and on the wedge. The center of pressure distance and velocity in the anteroposterior and mediolateral directions were calculated. Significantly larger magnitudes in most of the investigated variables were seen while standing with ankles in the dorsiflexion when compared with standing with the ankle joints in a natural position (p \u3c .05). Plantarflexion increased the center of pressure anteroposterior velocity by 87% when compared with a natural stance (p \u3c .05). Standing on the foam surfaces resulted in increases in all of the center of pressure measures by an average of 38% in all of the ankle conditions

Une nouvelle approche pour la gestion de flux temps réels basée sur l'algorithme EDF

Pour répondre aux exigences temporelles de flux temps réels, beaucoup de techniques d'ordonnancement de paquets ont été proposées dans la littérature, pour être utilisées au niveau de routeurs IP. La technique utilisant l'algorithme EDF a attiré une attention particulière, car l'optimalité de cet algorithme a été prouvée pour un nombre important de critères. Cependant la complexité et le surcoût induits par l'algorithme EDF ont constitué toujours un handicap majeur empêchant son implémentation. Dans ce papier, nous proposons une nouvelle approche d'ordonnancement, dite hybride, qui permet de combiner la puissance de EDF et la simplicité de l'algorithme standard FIFO. l'approche proposée a une complexité beaucoup plus réduite que celle de EDF. Les résultats de simulation soulignent l'efficacité de cette approche hybride

Presynaptic action of neurotensin on dopamine release through inhibition of D2 receptor function

<p>Abstract</p> <p>Background</p> <p>Neurotensin (NT) is known to act on dopamine (DA) neurons at the somatodendritic level to regulate cell firing and secondarily enhance DA release. In addition, anatomical and indirect physiological data suggest the presence of NT receptors at the terminal level. However, a clear demonstration of the mechanism of action of NT on dopaminergic axon terminals is lacking. We hypothesize that NT acts to increase DA release by inhibiting the function of terminal D2 autoreceptors. To test this hypothesis, we used fast-scan cyclic voltammetry (FCV) to monitor in real time the axonal release of DA in the nucleus accumbens (NAcc).</p> <p>Results</p> <p>DA release was evoked by single electrical pulses and pulse trains (10 Hz, 30 pulses). Under these two stimulation conditions, we evaluated the characteristics of DA D₂autoreceptors and the presynaptic action of NT in the NAcc shell and shell/core border region. The selective agonist of D₂autoreceptors, quinpirole (1 μM), inhibited DA overflow evoked by both single and train pulses. In sharp contrast, the selective D₂receptor antagonist, sulpiride (5 μM), strongly enhanced DA release triggered by pulse trains, without any effect on DA release elicited by single pulses, thus confirming previous observations. We then determined the effect of NT (8–13) (100 nM) and found that although it failed to increase DA release evoked by single pulses, it strongly enhanced DA release evoked by pulse trains that lead to prolonged DA release and engage D₂autoreceptors. In addition, initial blockade of D₂autoreceptors by sulpiride considerably inhibited further facilitation of DA release generated by NT (8–13).</p> <p>Conclusion</p> <p>Taken together, these data suggest that NT enhances DA release principally by inhibiting the function of terminal D₂autoreceptors and not by more direct mechanisms such as facilitation of terminal calcium influx.</p

Peri-adolescent drinking of ethanol and/or nicotine modulates astroglial glutamate transporters and metabotropic glutamate receptor-1 in female alcohol-preferring rats

Impairment in glutamate neurotransmission mediates the development of dependence upon nicotine (NIC) and ethanol (EtOH). Previous work indicates that continuous access to EtOH or phasic exposure to NIC reduces expression of the glutamate transporter-1 (GLT-1) and cystine/glutamate antiporter (xCT) but not the glutamate/aspartate transporter (GLAST). Additionally, metabotropic glutamate receptors (mGluRs) expression was affected following exposure to EtOH or NIC. However, little is known about the effects of EtOH and NIC co-consumption on GLT-1, xCT, GLAST, and mGluR1 expression. In this study, peri-adolescent female alcohol preferring (P) rats were given binge-like access to water, sucrose (SUC), SUC-NIC, EtOH, or EtOH-NIC for four weeks. The present study determined the effects of these reinforcers on GLT-1, xCT, GLAST, and mGluR1 expression in the nucleus accumbens (NAc), hippocampus (HIP) and prefrontal cortex (PFC). GLT-1 and xCT expression were decreased in the NAc following both SUC-NIC and EtOH-NIC. In addition, only xCT expression was downregulated in the HIP in both of these latter groups. Also, glutathione peroxidase (GPx) activity in the HIP was reduced following SUC, SUC-NIC, EtOH, and EtOH-NIC consumption. Similar to previous work, GLAST expression was not altered in any brain region by any of the reinforcers. However, mGluR1 expression was increased in the NAc in the SUC-NIC, EtOH, and EtOH-NIC groups. These results indicate that peri-adolescent binge-like drinking of EtOH or SUC with or without NIC may exert differential effects on astroglial glutamate transporters and receptors. Our data further parallel some of the previous findings observed in adult rats