Joint compensation of multiple RF impairments in MIMO STBC systems

In this paper, we propose a compensation method for the joint effect of high-power amplifier (HPA) nonlinearity, in-phase/quadrature-phase (I/Q) imbalance and crosstalk in multiple-input multiple-output (MIMO) orthogonal space-time block coding (OSTBC) systems. The performance of the MIMO OSTBC equipped with the proposed compensation mechanism is evaluated in terms of average symbol error probability and system capacity, in Rayleigh fading channels. Numerical results are provided and show the effects on performance of several system parameters, namely, the HPA parameters, image-leakage ratio, crosstalk, numbers of antennas, and phase-shift keying modulation order.

Influence of Atmospheric Conditions on mmWave CATR Facilities: Formulation and Compensation Scheme

The performance of a CATR relies on the planarity of the synthesized test wave, which is generated within a bounded volume for which specifications are drawn. Millimetre-wave facilities deal with the classical limitations of this frequency band, among which two become critical in our analysis: time-extensive acquisition campaigns and impact of environmental variables. Both features become more evident when increasing the frequency of operation. The variation in atmospheric variables, such as humidity, temperature and pressure has an influence over the performance of all the elements of the facility. The instrumentation behavior is influenced both by the warming up process, and the ambience conditions that surround the equipment. On the changes of the atmosphere itself, they affect the electromagnetic wave propagation, given the physical link between the conditions of the atmosphere and its electric properties as an electromagnetic waves propagation medium

Joint Compensation of I/Q Impairments and PA Nonlinearity for Concurrent Dual-Band Transmitters using Two-Box Model

A novel two-box model for joint compensation of nonlinear distortion introduced from both in-phase/quadrature modulator and power amplifier is proposed for concurrent dual-band wireless transmitters. Compensation of nonlinear distortion is accomplished in two phases, where phases are identified separately. It is shown that complexity of the digital predistortion is reduced. The performance of the proposed model is evaluated in terms of ACPR, EVM and NMSE improvements using 1.4 MHz LTE and WCDMA signals.

Analysis and compensation for the joint effects of HPA nonlinearity, I/Q imbalance and crosstalk in MIMO beamforming systems

In this paper, we investigate the joint effects of high-power amplifier (HPA) nonlinearity, in-phase/quadrature-phase (I/Q) imbalance and crosstalk, on the performance of multiple-input multiple-output (MIMO) transmit beamforming (TB) systems, and propose a compensation method for the three impairments together. The performance of the MIMO TB system equipped with the proposed compensation scheme is evaluated in terms of average symbol error probability and capacity when transmissions are performed over uncorrelated Rayleigh fading channels. Numerical results are provided and show the effects on performance of several system parameters, namely, the HPA parameters, image-leakage ratio, crosstalk, numbers of antennas, length of pilot symbols and phase-shift keying modulation order.

Experimental study applied to an industrial robot by using variable structure controllers and friction compensation

Control of an industrial robot is mainly a problem of dynamics. It includes non-linearities, uncertainties and external perturbations that should be considered in the design of control laws. In this work, two control strategies based on variable structure controllers (VSC) and a PD control algorithm are compared in relation to the tracking errors considering friction. The controller's performances are evaluated by adding an static friction model. Simulations and experimental results show it is possible to diminish tracking errors by using a model based friction compensation scheme. A SCARA robot is used to illustrate the conclusions of this paper.

Wildlife damage, insurance/compensation for farmers and conservation: Sri Lankan elephants as a case

The interference with agriculture has been recognised as the main cause for the current conflict between farmers and wild elephants in Sri Lanka, as elsewhere in the Asian elephant range. Thus compensating farmers for the damages caused by elephants is essential, if this endangered species is to survive in the long run. This paper explores the practicality of establishing an improved publicly funded insurance/compensation scheme to recompense farmers for the elephant damages. It does so by analysing results from two contingent valuation surveys undertaken in Sri Lanka. We find that possible public support of farmers plus urban dwellers significantly exceeds the financial requirement of the insurance scheme proposed in this study for perpetuity. The article also shows that it is often inappropriate from an economic viewpoint to analyse crop insurance as if it only involves the insurance of a private good because important positive externalities can arise from ‘crop’ damages by wildlife, e.g. elephants. The use of agricultural land by some species is essential for their long-term survival and this is often positively valued by the community as a whole.

Automatic motion compensation of free breathing acquired myocardial perfusion data by using independent component analysis

Images acquired during free breathing using first-pass gadolinium-enhanced myocardial perfusion magnetic resonance imaging (MRI) exhibit a quasiperiodic motion pattern that needs to be compensated for if a further automatic analysis of the perfusion is to be executed. In this work, we present a method to compensate this movement by combining independent component analysis (ICA) and image registration: First, we use ICA and a time?frequency analysis to identify the motion and separate it from the intensity change induced by the contrast agent. Then, synthetic reference images are created by recombining all the independent components but the one related to the motion. Therefore, the resulting image series does not exhibit motion and its images have intensities similar to those of their original counterparts. Motion compensation is then achieved by using a multi-pass image registration procedure. We tested our method on 39 image series acquired from 13 patients, covering the basal, mid and apical areas of the left heart ventricle and consisting of 58 perfusion images each. We validated our method by comparing manually tracked intensity profiles of the myocardial sections to automatically generated ones before and after registration of 13 patient data sets (39 distinct slices). We compared linear, non-linear, and combined ICA based registration approaches and previously published motion compensation schemes. Considering run-time and accuracy, a two-step ICA based motion compensation scheme that first optimizes a translation and then for non-linear transformation performed best and achieves registration of the whole series in 32 ± 12 s on a recent workstation. The proposed scheme improves the Pearsons correlation coefficient between manually and automatically obtained time?intensity curves from .84 ± .19 before registration to .96 ± .06 after registration

Massive MIMO with I/Q imbalance: Performance analysis and compensation

In this paper, we consider the uplink of a single-cell massive multiple-input multiple-output (MIMO) system with inphase and quadrature-phase imbalance (IQI). This scenario is of particular importance in massive MIMO systems, where the deployment of lower-cost, lower-quality components is desirable to make massive MIMO a viable technology. Particularly, we investigate the effect of IQI on the performance of massive MIMO employing maximum-ratio combining (MRC) receivers. In order to study how IQI affects channel estimation, we derive a new channel estimator for the IQI-impaired model and show that IQI can substantially downgrade the performance of MRC receivers. Moreover, a low-complexity IQI compensation scheme, suitable for massive MIMO, is proposed which is based on the IQI coefficients' estimation and it is independent of the channel gain. The performance of the proposed compensation scheme is analytically evaluated by deriving a tractable approximation of the ergodic achievable rate and providing the asymptotic power scaling laws assuming transmission over Rayleigh fading channels with log-normal large-scale fading. Finally, we show that massive MIMO effectively suppresses the residual IQI effects, as long as, the compensation scheme is applied.

L'adoption d'un régime d'indemnisation sans égard à la faute en faveur des victimes d'infections nosocomiales, et pourquoi pas?

Phénomène à haute prévalence dans le monde entier, les infections acquises au cours de la prestation de soins de santé constituent une menace importante pour la santé publique. Il s’agit d’une réalité inéluctable du système de santé qui touche de nombreuses victimes en les affectant de dommages variés. Fruit d’une interaction complexe entre divers facteurs, ces infections représentent un lourd fardeau pour les victimes comme pour la société, tant au plan physique, mental et financier. Bien que les infections nosocomiales semblent être au cœur des préoccupations des autorités sanitaires québécoises, l’indemnisation des victimes demeure problématique. Actuellement, l’indemnisation se fait via le régime traditionnel de responsabilité civile mais nombreux sont les obstacles auxquels font face les patients désirant obtenir compensation. Les règles classiques s’avèrent difficiles d’application dans un contexte où la source de l’infection est souvent inconnue et les facteurs ayant pu contribuer à son développement sont multiples. Face à cette problématique et à l’insatisfaction ressentie, certaines juridictions étrangères ont reconnu le caractère inadapté du régime traditionnel et ont implanté un régime d’indemnisation sans égard à la faute dans l’espoir d’améliorer le sort des victimes. Le Québec a opté pour la même solution dans divers domaines, tels que les accidents automobiles et la vaccination. Ce mémoire propose une étude approfondie de l’opportunité d’adopter, en droit québécois, un régime d’indemnisation sans égard à la faute bénéficiant aux victimes d’infections nosocomiales. L’objectif de ce projet est de faire une esquisse des caractéristiques assurant l’efficacité et la viabilité d’un tel régime.

A copyright exception for private copying in the United Kingdom

This paper discusses the proposed copyright exception for private copying in the UK in the aftermath of the Hargreaves Review. It explores the options by which the exception shall retain a realistic scope without significantly impacting on the interests of the rightholders and addresses the concept of possible harm that may arise due to private copying. It concludes that an exception for copying of content legally owned by an individual to another medium or device for private use corresponds to consumers’ reasonable expectations without causing more than minimal harm to the rightholders’ interests and without requiring an accompanying introduction of a fair compensation scheme.

Paying for long-term performance: restructuring bankers’ pay for risk regulation

The purpose of this paper is to propose hybrid capital securities as a new approach to compensation for senior bank executives and risk-takers instead of cash or equity-based compensation currently adopted by the industry. The global financial turmoil indicated that misaligned pay-for-performance compensation arrangements encouraged management short-termism and rewarded excessive risk-taking behaviour in Anglo-Saxon system. Rather than regulating specific instruments and processes, we believe that it is much more efficient to overhaul the compensation scheme to align it with risk management and governance. This empirical paper investigates the European hybrid market by employing data from the Merrill Lynch Global Index System from 2000 to 2010. Our paper contributes to both literature and practices by designing a structured scheme to tie the executive’s interests to long-term performance of the bank, the goal of regulators and the economy at large which consequently reduce the probability of future bank failures.

Utilização da lógica difusa no controle inteligente de sistemas eletro-hidráulicos

Electro-hydraulic servo-systems are widely employed in industrial applications such as robotic manipulators, active suspensions, precision machine tools and aerospace systems. They provide many advantages over electric motors, including high force to weight ratio, fast response time and compact size. However, precise control of electro-hydraulic systems, due to their inherent nonlinear characteristics, cannot be easily obtained with conventional linear controllers. Most flow control valves can also exhibit some hard nonlinearities such as deadzone due to valve spool overlap on the passage´s orifice of the fluid. This work describes the development of a nonlinear controller based on the feedback linearization method and including a fuzzy compensation scheme for an electro-hydraulic actuated system with unknown dead-band. Numerical results are presented in order to demonstrate the control system performance