Cyclostationary analysis of analog least mean square loop for self-interference cancellation in in-band full-duplex systems

© 2017 IEEE. Analog least mean square (ALMS) loop is a promising mechanism to suppress self-interference (SI) in an in-band full-duplex (IBFD) system. In this letter, a general solution for the weighting error function is derived to investigate the performance of the ALMS loop employed in any IBFD system. The solution is then applied to IBFD systems with single carrier and multicarrier signaling. Due to the cyclostationary property of the transmitted signal, the weighting error function in the multicarrier system varies more significantly than in the single carrier. Therefore, if the ALMS loop can perfectly mimic the SI channel, SI in the single carrier system can be suppressed to a much smaller level than that in the multi-carrier counterpart

Sculpture as systematic growth

The foundation of my work is built upon the idea that everything is comprised of constituent components in which all of the components serve a function in the creation of the integrated whole. This way of thinking is consistent with the principles of systems, however large or small, complex or simple. Every system has parameters that define and frame the behavior of its set of interacting and interdependent components. What I am interested in is not necessarily the final output of the system, but rather, the process in which the components interact within the parameters of the system and how the relationships of these interactions affect the outcome

Noise and vibration from building-mounted micro wind turbines Part 2: Results of measurements and analysis

Description To research the quantification of vibration from a micro turbine, and to develop a method of prediction of vibration and structure borne noise in a wide variety of installations in the UK. Objective The objectives of the study are as follows: 1) Develop a methodology to quantify the amount of source vibration from a building mounted micro wind turbine installation, and to predict the level of vibration and structure-borne noise impact within such buildings in the UK. 2) Test and validate the hypothesis on a statically robust sample size 3) Report the developed methodology in a form suitable for widespread adoption by industry and regulators, and report back on the suitability of the method on which to base policy decisions for a future inclusion for building mounted turbines in the GPDO

Evaluating the Temporal and the Spatial Heterogeneity of the European Convergence Process, 1980-1999

In this paper, we suggest a general framework that allows testing simultaneously for temporal heterogeneity, spatial heterogeneity and spatial autocorrelation in b-convergence models. Based on a sample of 145 European regions over the 1980-1999 period, we estimate a Seemingly Unrelated Regression Model with spatial regimes and spatial autocorrelation for two sub-periods: 1980-1989 and 1989-1999. The assumption of temporal independence between the two-periods is rejected and the estimation results point to the presence of spatial error autocorrelation in both sub-periods and spatial instability in the second sub-period, indicating the formation of a convergence club between the peripheral regions of the European Union.b-convergence models, spatial autocorrelation, convergence clubs, temporal instability

RATIONALE, MOTIVATION AND EFFECT OF FOREIGN INVESTMENT IN VIETNAMESE COMPANIES

Existing literatures have documented that foreign investors in developed markets hold disproportionately more shares of firms with high turnover rates. In Vietnam, I find evidence that foreign investor ownership percentage is higher in firms with lower turnover rates, firms located in the south of Vietnam, firms listed on the Hochiminh stock exchange, firms that are listed longer on the exchange, large firms, and firms with low past returns. The effect of turnover rate on foreign ownership percentage is weak, while the coefficients of firm size and firm age since IPO are consistently robust. I find that foreign investors hold more in firms with lower government ownership, and firms audited by a prestigious international audit company only holds for firms listed on the Hanoi exchange. I find that the thesis that foreign investor percentage ownership stakes are higher in firms with higher current ratios holds only for the firms listed on the Hochiminh stock exchange. Although average firm size is higher for State-Owned Enterprises (SOEs) and foreign investors strongly prefer investing in large size firms, they strongly show their preference in firms other than SOEs. By excluding the effect of size, I find that foreign ownership percentage stakes in firms listed on the Hanoi exchange are lower than foreign ownership percentage stakes in firms listed on the Hochiminh exchange. Interestingly, since dividend began being taxed, foreigner ownership percentage has been lower in firms with high dividend yields

Analog least mean square loop for self-interference cancellation: A practical perspective

©2020 by the authors. Licensee MDPI, Basel, Switzerland. Self-interference (SI) is the key issue that prevents in-band full-duplex (IBFD) communications from being practical. Analog multi-tap adaptive filter is an efficient structure to cancel SI since it can capture the nonlinear components and noise in the transmitted signal. Analog least mean square (ALMS) loop is a simple adaptive filter that can be implemented by purely analog means to sufficiently mitigate SI. Comprehensive analyses on the behaviors of the ALMS loop have been published in the literature. This paper proposes a practical structure and presents an implementation of the ALMS loop. By employing off-the-shelf components, a prototype of the ALMS loop including two taps is implemented for an IBFD system operating at the carrier frequency of 2.4 GHz. The prototype is firstly evaluated in a single carrier signaling IBFD system with 20 MHz and 50 MHz bandwidths, respectively. Measured results show that the ALMS loop can provide 39 dB and 33 dB of SI cancellation in the radio frequency domain for the two bandwidths, respectively. Furthermore, the impact of the roll-off factor of the pulse shaping filter on the SI cancellation level provided by the prototype is presented. Finally, the experiment with multicarrier signaling shows that the performance of the ALMS loop is the same as that in the single carrier system. These experimental results validate the theoretical analyses presented in our previous publications on the ALMS loop behaviors

Analog Least Mean Square Loop with I/Q Imbalance for Self-Interference Cancellation in Full-Duplex Radios

© 1967-2012 IEEE. Analog least mean square (ALMS) loop is a promising structure for self-interference (SI) mitigation in full-duplex radios due to its simplicity and adaptive capability. However, being constructed from in-phase/quadrature (I/Q) demodulators and modulators to process complex signals, the ALMS loop may face I/Q imbalance problems. Thus, in this paper, the effects of frequency-independent I/Q imbalance in the ALMS loop are investigated. It is revealed that I/Q imbalance affects the loop gain and the level of SI cancellation. The loop gain can be easily compensated by adjusting the gain at other stages of the ALMS loop. Meanwhile, the degradation on cancellation performance is proved to be insignificant even under severe conditions of I/Q imbalance. In addition, an upper bound of the degradation factor is derived to provide an essential reference for the system design. Simulations are conducted to confirm the theoretical analyses

Analog Least Mean Square Loop for Self-Interference Cancellation: Implementation and Measurements

Analog least mean square (ALMS) loop is a simple and efficient adaptive filter to cancel self-interference (SI) in in-band full-duplex (IBFD) radios. This paper proposes a practical structure and presents an implementation of the ALMS loop. By employing off-the-shelf components, a prototype of the ALMS loop including two taps is implemented. The prototype is evaluated in IBFD systems which have 20 MHz and 50 MHz bandwidths, respectively, with the carrier frequency of 2.4 GHz. The performance of the prototype with different roll-off factors of the transmit pulse shaping filter is also examined. Experimental results show that the ALMS loop can provide 39 dB and 33 dB of SI cancellation for the two systems, respectively. Furthermore, when the roll-off factor of the pulse shaping filter changes, different levels of cancellation given by the prototype are also demonstrated accordingly. These experimental results validate the theoretical analyses presented in our previous publications on the ALMS loop behaviors

Dynamique de la teneur en carbone et en azote des sols dans les systèmes d’exploitation du Ferlo : cas du CRZ de Dahra

Objectif : Cette étude, réalisée au Centre de Recherches Zootechniques (CRZ) de Dahra situé en Région sylvopastorale du Sénégal, a pour objectif d’apprécier l’évolution de la teneur en carbone, en azote et le stock de carbone du sol dans ses différents systèmes d’exploitation.Méthodologie et résultats : En 2011, des échantillons de sols (à 0-20 cm et 20 – 40 cm) ont été prélevés au niveau des mêmes sites que ceux qui ont fait l’objet d’analyse de sols en 1962, afin de déterminer la teneur en carbone et azote du sol. Le nombre d’échantillons est fonction de la superficie des différents types de sols rencontrés. L’utilisation de la cartographie nous a permis de déterminer le nombre d’échantillon prélevé sur chaque système d’exploitation. Au niveau du CRZ de Dahra, l’analyse des paramètres pédologiques (teneur en carbone, en azote et rapport C/N) de l’horizon 0-20 cm, n’a pas révélé de différence significative entre 1962 et 2011. Par contre, dans l’horizon 20-40 cm, seule la teneur en azote présente une hausse significative entre ces deux périodes. S’agissant des systèmes d’exploitation du CRZ de Dahra, l’analyse de la teneur en carbone, en azote et du rapport C/N de l’horizon 0-20 cm, n’a pas révélé de différence significative aussi bien pour l’année 1962 que celle de 2011. Au niveau de l’horizon 20-40 cm, parmi les paramètres étudiés, seul la teneur en carbone de 1962 présentait une différence significative (au seuil de 5%) entre les systèmes de cultures et les pâturages. Le stock de carbone du centre est en moyenne de 0,08±0,03 et 0,06±0,02 t/ha respectivement pour les horizons 0-20 et 20-40 cm. Celui-ci est plus important au niveau des gommiers et plus faibles dans les systèmes de culture et les pâturages.Conclusion et application des résultats : Cette étude a permis de montrer qu’au niveau du CRZ de Dahra à vocation essentiellement pastorale, le carbone et l’azote du sol, présente une certaine stabilité dans les différents systèmes d’exploitation. Toutefois, les gommiers présentent les teneurs en carbone et en azote du sol les plus importantes. Ces résultats peuvent servir de données d’entrée aux modèles de prévision de la séquestration du carbone et de l’azote du sol des écosystèmes sahéliens pastoraux, être valorisés en aménagement pastoral et agro-sylvopastoral en vue d’une meilleure préservation de l’environnement et de la gestion de la fertilité du sol.Mots clés : carbone, l'azote, le contenu, les sol

ROI detection in SPR measurements and molecule binding parameter estimation

Since 1983 when Surface Plasmon Resonance (SPR) was first proposed, it has become a widelyusedmethodology for various biosensing applications. In a SPR biosensing system in arrayformat, locating the region of interest (ROI) and estimating themolecule binding parametersfrom the SPR measurements are of great importance. In this thesis, we addressed these twochallenges by detecting the ROIs automatically and estimating the parameters optimally throughthe minimization of the mean square error (MSE).We first pre-processed the SPR video frame images to help enhance the ROI detectionperformance, and then applied the randomized Hough transformto automatically detect theROIs. With hundreds or even thousands of ROIs on a single SPR video frame image, our procedureto automatically detect the ROIs greatly reduced the labor to assign the ROIs.We then extracted the image gray level intensity data fromthe ROIs as a function of time,which were used to estimate the molecule binding parameters, ka (the rate of association) andkd (the rate of dissociation). These binding parameters are vital in biosensing applications. Inthis research we use a Particle SwarmOptimization (PSO) algorithm to estimate the parametersand compared the performance to the commercially used Levenberg-Marquardt (LM) algorithm,a gradient based algorithm. Our PSO algorithm performed better than LM achieving a muchlower MSE for all the active ROIs