Analysis of a convenient information bound for general quantum channels

Open questions from Sarovar and Milburn (2006 J.Phys. A: Math. Gen. 39 8487) are answered. Sarovar and Milburn derived a convenient upper bound for the Fisher information of a one-parameter quantum channel. They showed that for quasi-classical models their bound is achievable and they gave a necessary and sufficient condition for positive operator-valued measures (POVMs) attaining this bound. They asked (i) whether their bound is attainable more generally, (ii) whether explicit expressions for optimal POVMs can be derived from the attainability condition. We show that the symmetric logarithmic derivative (SLD) quantum information is less than or equal to the SM bound, i.e.\ $H(\theta) \leq C_{\Upsilon}(\theta)$ and we find conditions for equality. As the Fisher information is less than or equal to the SLD quantum information, i.e. $F_M(\theta) \leq H(\theta)$, we can deduce when equality holds in $F_M(\theta) \leq C_{\Upsilon}(\theta)$. Equality does not hold for all channels. As a consequence, the attainability condition cannot be used to test for optimal POVMs for all channels. These results are extended to multi-parameter channels.Comment: 16 pages. Published version. Some of the lemmas have been corrected. New resuts have been added. Proofs are more rigorou

Optimal estimation of one parameter quantum channels

We explore the task of optimal quantum channel identification, and in particular the estimation of a general one parameter quantum process. We derive new characterizations of optimality and apply the results to several examples including the qubit depolarizing channel and the harmonic oscillator damping channel. We also discuss the geometry of the problem and illustrate the usefulness of using entanglement in process estimation.Comment: 23 pages, 4 figures. Published versio

Robust H∞ control for a class of nonlinear discrete time-delay stochastic systems with missing measurements

This is the post print version of the article. The official published version can be obtained from the link - Copyright 2009 Elsevier LtdThis paper is concerned with the problem of robust H∞ output feedback control for a class of uncertain discrete-time delayed nonlinear stochastic systems with missing measurements. The parameter uncertainties enter into all the system matrices, the time-varying delay is unknown with given low and upper bounds, the nonlinearities satisfy the sector conditions, and the missing measurements are described by a binary switching sequence that obeys a conditional probability distribution. The problem addressed is the design of an output feedback controller such that, for all admissible uncertainties, the resulting closed-loop system is exponentially stable in the mean square for the zero disturbance input and also achieves a prescribed H∞ performance level. By using the Lyapunov method and stochastic analysis techniques, sufficient conditions are first derived to guarantee the existence of the desired controllers, and then the controller parameters are characterized in terms of linear matrix inequalities (LMIs). A numerical example is exploited to show the usefulness of the results obtained.This paper was not presented at any IFAC meeting. This paper was recommended for publication in revised form by Associate Editor Dragan Nešic under the direction of Editor Hassan K. Khalil. This work was supported in part by the Engineering and Physical Sciences Research Council (EPSRC) of the U.K. under Grant GR/S27658/01, the City University of Hong Kong under Grant 7001992, the Royal Society of the U.K. under an International Joint Project, the Natural Science Foundation of Jiangsu Province of China under Grant BK2007075, the National Natural Science Foundation of China under Grant 60774073, and the Alexander von Humboldt Foundation of Germany

Robust filtering with stochastic nonlinearities and multiple missing measurements

This is the post print version of the article. The official published version can be obtained from the link - Copyright 2009 Elsevier LtdThis paper is concerned with the filtering problem for a class of discrete-time uncertain stochastic nonlinear time-delay systems with both the probabilistic missing measurements and external stochastic disturbances. The measurement missing phenomenon is assumed to occur in a random way, and the missing probability for each sensor is governed by an individual random variable satisfying a certain probabilistic distribution over the interval . Such a probabilistic distribution could be any commonly used discrete distribution over the interval . The multiplicative stochastic disturbances are in the form of a scalar Gaussian white noise with unit variance. The purpose of the addressed filtering problem is to design a filter such that, for the admissible random measurement missing, stochastic disturbances, norm-bounded uncertainties as well as stochastic nonlinearities, the error dynamics of the filtering process is exponentially mean-square stable. By using the linear matrix inequality (LMI) method, sufficient conditions are established that ensure the exponential mean-square stability of the filtering error, and then the filter parameters are characterized by the solution to a set of LMIs. Illustrative examples are exploited to show the effectiveness of the proposed design procedures.This work was supported in part by the Shanghai Natural Science Foundation under Grant 07ZR14002, the Engineering and Physical Sciences Research Council (EPSRC) of the UK under Grant GR/S27658/01, an International Joint Project sponsored by the Royal Society of the UK, the Nuffield Foundation of the UK under Grant NAL/00630/G and the Alexander von Humboldt Foundation of Germany

Observer-based networked control for continuous-time systems with random sensor delays

This is the post print version of the article. The official published version can be obtained from the link - Copyright 2009 Elsevier LtdThis paper is concerned with the networked control system design for continuous-time systems with random measurement, where the measurement channel is assumed to subject to random sensor delay. A design scheme for the observer-based output feedback controller is proposed to render the closed-loop networked system exponentially mean-square stable with H∞ performance requirement. The technique employed is based on appropriate delay systems approach combined with a matrix variable decoupling technique. The design method is fulfilled through solving linear matrix inequalities. A numerical example is used to verify the effectiveness and the merits of the present results.This paper was not presented at any IFAC meeting. This paper was recommended for publication in revised form by Associate Editor George Yin under the direction of Editor Ian R. Petersen. This work was supported in part by the Royal Society of the UK, the National Natural Science Foundation of China (60774047, 60674055) and the Taishan Scholar Programs Foundation of Shandong Province, China

Décentralisation des politiques éducatives en Côte d’Ivoire : Les effets structurants des motivations politiques sur les résultats de l’action publique locale

La décentralisation est apparue vers les années 80 en Côte d’Ivoire au moment de la diminution des ressources de l’État et des restrictions budgétaires imposées par le FMI. Au nombre des solutions envisagées pour juguler la conjoncture économique, il a été envisagé le transfert d’importantes prérogatives de l’Etat central vers les collectivités territoriales parmi lesquelles figurent le service public de l’enseignement. Si la décentralisation des politiques éducatives a été conçue à l’origine pour contribuer à l’efficacité de l’action publique en la rapprochant du citoyen, ses résultats semblent de plus en plus mitigés. Pour rendre compte de l’inefficacité du processus, la crise économique a été majoritairement mobilisée comme principal facteur explicatif. Bien que n’éludant pas la pertinence et la valeur heuristique de cet argument, ce travail s’intéresse quant à lui aux logiques propres des acteurs, piste qui semble n’avoir pas été suffisamment explorée. En d’autres termes, l’étude soutient que les politiques éducatives locales sont inefficaces parce qu’elles sont structurées par les intérêts matériels et positionnels des décideurs liés aux enjeux électoraux. The decentralization emerged in the 1980s in Côte d’Ivoire at a time of declining state resources and budgetary restrictions imposed by the IMF. Among the solutions envisaged to curb the economic situation, the transfer of important prerogatives from the central state to local authorities, including the public education service, was envisaged. Although the decentralisation of education policies was originally designed to contribute to the effectiveness of public action by bringing it closer to the citizen, its results seem increasingly mixed. To account for the inefficiency of the process, the economic crisis has been mobilized as the main explanatory factor. While not evading the relevance and the heuristic value of this argument, this work focuses on the actors' own logics, an avenue that seems to have been insufficiently explored. In other words, the study argues that local education policies are ineffective because they are structured by the material and positional interests of decisionmakers linked to electoral issues

Land-Use in African Rangelands: A Study of Change in Bay Region, Somalia

Rangelands In Bay region are used for three main economic activities: livestock grazing, dry-farming and wood collection. Livestock grazing is practised by about 99 per cent of households in the area, and this percentage not only shows that grazing practices are common among the local inhabitants, but that they are controlled by individual households. This implies that herd management techniques (for example, herd size and structure, and livestock movements and sales) are directly related to grazing methods, herd composition and the socio-economic obligations of the pastoral society, rather than to the environmental maintenance of pasturelands. The reason is that pasturelands are communally owned, whilst animals are individually owned. Thus, rangeland resources have come under increasing grazing pressure, owing to the increase in the numbers of livestock, as well as to the changes in herd structure from a reliance on camels and smallstock to a reliance on cattle. Dry-farming is another form of land-use in Bay region. This land-use activity is common too, as about 93 per cent of the pastoral households are agro-pastoralists. Nevertheless, dry-farming lands occupy only about 11% of the region's land. This is not only due to the amount of rainfall, and its distribution, but also to the distribution of Vertisols, the most fertile soils in the region. However, there has been an increase in the area of dry-farming lands in recent years, although this farming is still largely unaffected by modern farming techniques, and weeds infestation. insect and bird damage and other crop problems are common in the region. Wood collection is the third land-use type, being in those range areas covered with woody plants. There is no clear division between those rangelands used for grazing and those used for wood collection purposes. This is because range plants provide both a substantial supply of forage for livestock, as well as fuelwood and timber for people. Wood collection for household needs is carried out freely by pastoral groups, most of it being collected from the nearest woodlands, whilst timber for household building and fences is often gathered from woodlots further afield. Charcoal production is another form of wood collection in Bay region. In fact, the region is one of the major suppliers of charcoal to the consumer centre in Mogadishu. There has been an increase in recent years in the amount of charcoal produced and exported from Bay region and surrounding areas to Mogadishu. A total of 41 selected ecological and socio-economic factors, relating to land-use changes, have been perceived to have changed over the past 20 years in Bay region. It would seem that these land-use changes are more likely to be as a result of increasing human pressures on the rangeland resources in terms of overgrazing, overcultivation and overcutting of woody vegetation, rather than of changing environmental factors such as rainfall. Such pressures have resulted from various factors, such as the communal use of pasturelands and woodlands: the growth of commercial pastoralism; the scale of pastoral development; and the growth of unplanned pastoral settlements. As such. an optimal interplay, between the rangeland potentials and land-use activities. plays a prominent role in the sound management of unreliable range resources

Strategic and implementation issues regarding ECB Monetary Policy

This paper identifies the impact of the most important ECB’s non-standard monetary policy measures in the euro area. The global recession has been reflected in the slowdown of the U.S. economy and the largest economies of Europe and Asia. The 2008 and 2014 financial crisis hit the European financial system, whereas during 2010 and early 2011 Eurozone faced the hardest time in the so-called debt crisis coupled with a drop in market confidence. Financial markets faced some problems of solvency of countries with higher debt and fiscal deficits, such as the sovereign debt crisis bubbles in Spain and Italy. The European Central Bank reacted by imposing strategic and technical measures to fuel the banks' liquidity needs, to fight a risky credit crisis and to restore investor’s confidence within a heterogeneous Eurozone countries environment. The ECB implemented the unconventional measures, which aimed at lowering and flattening the yield curve by reducing the interest rate level and shrinking the gap between long- and short-term interest rates. The study can be applied to improve the monetary policy measures and reduce risks in the financial sector. The questions, which need to be addressed, relate to whether unconventional monetary policy works and what are the challenges in the long run

Upcycling of Cereal Byproducts: A Sustainable Opportunity to Valorize Wasted Nutrients and Derive Bioactive Compounds for Humans and Animals Nutrition and Health

With the global population projected to reach close to 10 billion by 2050, the escalating demand for cereals such as wheat, rice, corn, oat, and barley places significant pressure on production systems. These systems are increasingly vulnerable to the adverse impacts of climate change, threatening global food security. This article emphasizes the critical need to address these challenges and explores strategies for sustainable foodproduction, focusing on the opportunities that the upcycling of cereal byproducts offers for human and animal nutrition and health

Robust H-infinity filtering for 2-D systems with intermittent measurements

This paper is concerned with the problem of robust H∞ filtering for uncertain two-dimensional (2-D) systems with intermittent measurements. The parameter uncertainty is assumed to be of polytopic type, and the measurements transmission is assumed to be imperfect, which is modeled by a stochastic variable satisfying the Bernoulli random binary distribution. Our attention is focused on the design of an H∞ filter such that the filtering error system is stochastically stable and preserves a guaranteed H∞ performance. This problem is solved in the parameter-dependent framework, which is much less conservative than the quadratic approach. By introducing some slack matrix variables, the coupling between the positive definite matrices and the system matrices is eliminated, which greatly facilitates the filter design procedure. The corresponding results are established in terms of linear matrix inequalities, which can be easily tested by using standard numerical software. An example is provided to show the effectiveness of the proposed approac