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Abstract This study presents a simple metric to quantitatively evaluate the compensation of phase distortions in digital holographic microscopy. The metric calculates the difference between the minimum and maximum values in an unwrapped phase image. A phase compensation method based on the metric is proposed. Both the tilt and curvature distortions can be automatically compensated using this method, and specimen-free zones are unnecessary. It is also suitable for thick objects located in wide areas. The method using this evaluation metric has been tested and validated on several samples. With strong robustness and low computational complexity, this approach can result in accurate and effective quantitative phase imaging in holographic microscopy. [ABSTRACT FROM AUTHOR]

In this paper, a novel non-smooth observer is proposed to handle the soft measurement of the states of the sandwich system with dead zone. The convergence theorem of the non-smooth observer and its proof are given, respectively. After that, the experimental results are presented. The comparison between the proposed non-smooth scheme and the conventional method is illustrated. Finally, the robust observer is proposed for the sandwich system with dead zone and the states’ estimation results of the experimental equipment by the robust observer and the conventional non-robust observer have been compared in order to illustrate the necessity of proposing the robust one. [ABSTRACT FROM AUTHOR]

Abstract: Globalization is creating an interdependent space-faring world and new opportunities for international partnerships that strengthen space knowledge development and transfer. These opportunities have been codified in the Global Exploration Strategy, which endorses the “inspirational and educational value of space exploration” . Also, during the 2010 Heads of Space Agencies Summit celebrating the International Academy of Astronautics’ (IAA) 50th Anniversary, space-faring nations from across the globe issued a collective call in support of robust international partnerships to expand the frontiers of space exploration and generate knowledge for improving life on Earth . Educators play a unique role in this mission, developing strategic partnerships and sharing best educational practices to (1) further global understanding of the benefits of space exploration for life on Earth and (2) prepare the next generation of scientists required for the 21st Century space workforce. Educational Outreach (EO) programs use evidence-based, measurable outcomes strategies and cutting edge information technologies to transfer space-based science, technology, engineering and mathematics (STEM) knowledge to new audiences; create indigenous materials with cultural resonance for emerging space societies; support teacher professional development; and contribute to workforce development initiatives that inspire and prepare new cohorts of students for space exploration careers. The National Space Biomedical Research Institute (NSBRI), the National Aeronautics and Space Administration (NASA) and Morehouse School of Medicine (MSM) have sustained a 13-year space science education partnership dedicated to these objectives. This paper briefly describes the design and achievements of NSBRI''s educational programs, with special emphasis on those initiatives'' involvement with IAA and the International Astronautical Congress (IAC). The IAA Commission 2 Draft Report, Space for Africa, is discussed as a model for developing sustainable partnerships and indigenous programs that support Africa''s steady emergence as a global space-faring force. The IAC will provide timely: 2011 South Africa will provide timely feedback to refine that report''s strategies for space life sciences education and public engagement in Africa and around the globe. [Copyright &y& Elsevier]

Abstract: We analyze the robustness of a knowledge gradient (KG) policy for the multi-armed bandit problem. The KG policy is based on a one-period look-ahead, which is known to underperform in other learning problems when the marginal value of information is non-concave. We present an adjustment that corrects for non-concavity and approximates a multi-step look-ahead, and compare its performance to the unadjusted KG policy and other heuristics. We provide guidance for determining when adjustment will improve performance, and when it is unnecessary. We present evidence suggesting that KG is generally robust in the multi-armed bandit setting, which argues in favour of KG as an alternative to index policies. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a linear photometer circuit based on robust feedback compensation is presented. Here, the photodiode was modelled as a dynamic system and its mathematical model was obtained from the well-known equivalent circuit for a photodiode reported in scientific literature. Next, in order to make the output of the system robust against uncertainties and the inevitable disturbances that corrupt the response of the photometer circuit, a robust feedback controller was designed. Finally, the robust photometer circuit presented in this paper was compared against a conventional photometer circuit based on a transimpedance amplifier. The results of comparing the aforementioned photometers showed that the photometer based on robust control techniques is superior to the one based on the conventional design. The linear robust photometer circuit presented in this paper was used for making measurements of light at 670nm, its temperature coefficient was very low, and very high sensitivity and linearity characteristics were achieved. [Copyright &y& Elsevier]

Abstract: This paper addresses the problem of computing the delay intervals for stability of time-delay systems. Time-delays are frequently a source of instability and quite often difficult to estimate. The major features of the method are: (1) the delay uncertainty is represented by a relative error, i.e., h = h 0(1+ δ); (2) the time-delay system is recast by a representation that is compatible with robust control analysis, which requires a norm-bounded modeling uncertainty and stable transfer function; and (3) a new tool, i.e., singular phase value, is proposed to find the exact bounds on the delay that sufficiently stabilize the time-delay system. The method can be used to find the first delay interval for stability but it can also be extended to find other delay intervals using standard robust control tools; therefore, the proposed method is suitable for computer implementation. With a simple modification, the proposed method can also be used to test the robust stability of various controller schemes under closed-loop conditions. [Copyright &y& Elsevier]

Abstract: Most control algorithms for rigid robots are given in joint coordinates. However, since the task to be accomplished is expressed in Cartesian coordinates, inverse kinematics has to be computed in order to implement the control law. Alternatively, one can develop the necessary theory directly in workspace coordinates. This has the disadvantage of a more complex robot model. In this paper, a control-observer scheme is given to achieve exact Cartesian tracking without the knowledge of the manipulator dynamics nor computing inverse kinematics. Also, only joint measurements are used. [Copyright &y& Elsevier]

Abstract: Computational geometry has produced an impressive wealth of efficient algorithms. The robust implementation of these algorithms remains a major issue. Among the many proposed approaches for solving numerical non-robustness, Exact Geometric Computation (EGC) has emerged as one of the most successful. This survey describes recent progress in EGC research in three key areas: constructive zero bounds, approximate expression evaluation and numerical filters. [Copyright &y& Elsevier]

This paper deals with feedback controller synthesis for timed event graphs, where the number of initial tokens and time delays are only known to belong to intervals. We discuss here the existence and the computation of a robust controller set for uncertain systems that can be described by parametric models, the unknown parameters of which are assumed to vary between known bounds. Each controller is computed in order to guarantee that the closed-loop system behavior is greater than the lower bound of a reference model set and is lower than the upper bound of this set. The synthesis presented here is mainly based on dioid, interval analysis and residuation theory. [Copyright &y& Elsevier]

This paper presents an indirect pole-placement based adaptive control scheme for discrete linear time-invariant non-necessarily inversely stable and stabilizable systems. The scheme is a pole-placement type without requiring the plant inverse stability assumption. The control objective is that the plant output should asymptotically track in the absence of unmodeled dynamics and bounded disturbances a reference signal, given by an arbitrary stable filter, under a bounded tracking error while ensuring robust closed-loop stability. The adaptive stabilizability and the robustness of this system under the presence of unmodeled dynamics and, possibly, bounded disturbances, are proved without assuming the controllability of the modeled plant. A normalized least-squares algorithm with a relative adaptation dead-zone and ‘a posteriori’ modification of the parameter estimates is used to ensure the controllability of the modified estimation plant model at all sampling instants and at the limit. Such a property is crucial to solve the stable pole-placement problem. On the other hand, the relative adaptation dead-zone is included for robustness purposes under unmodeled dynamics and, possibly, bounded disturbances. [Copyright &y& Elsevier]

We consider a robust supervisory control problem to synthesize a supervisor for the nominal plant model which maximizes robustness. Cury and Krogh have first addressed this problem by unnecessarily restricting the upper bound of the legal behavior. In our previous work, we have solved the problem without restricting the upper bound of the legal behavior when the specification is described by prefix-closed languages. In this paper, we extend our previous work to the partial (event) observation case. First, we synthesize a supervisor that maximizes robustness. This result shows that robustness can be optimized under partial observation, while permissiveness cannot be optimized in general. We next consider a special case where all the controllable events are observable. In this special case, we synthesize a maximally permissive supervisor for the nominal plant model which maximizes not only the robustness but also permissiveness for the maximal set of admissible plant variations. [Copyright &y& Elsevier]

This paper addresses the existence and design methods of reduced-order controllers for the H∞ control problem with unstable invariant zeros in the state-space realization of the transfer function matrix from the control input to the controlled error or from the exogenous input to the observation output, where the realization is induced from a stabilizable and detectable realization of the generalized plant. This paper presents a new controller degree bound for the H∞ control problem in terms of the minimal rank of the system matrix pencils of these two transfer function matrices in the unstable region. When the unstable invariant zero exists, this paper shows that reduced-order controllers with orders strictly less than that of the generalized plant exist if the H∞ control problem is solvable. Moreover, this paper shows that the computational problem of finding the controllers with the new degree bound is convex by providing two linear matrix inequality-based design methods (algorithms) for constructing the reduced-order controllers. The results developed in this paper are valid both for the continuous- and discrete-time H∞ control problems. [Copyright &y& Elsevier]

This paper considers the simultaneous fault detection and control (SFDC) problem. This problem is formulated as a mixed H2/H∞ optimization problem and its solution is presented in terms of two coupled Riccati equations. This solution yields controller/detector systems of modest complexity. An easily implementable design algorithm summarizes the methodology presented in the paper. [Copyright &y& Elsevier]

• The association between the math gender gap and gender equality is not robust • Country-level confounding factors are relevant • The relationship is non-existent in OECD and non-OECD countries • Gender equality is associated with a narrowing of the math gender gap in poorer countries In their seminal article, Guiso et al. (2008) uncover a positive relationship between several measures of gender equality and the math gender gap (which tends to favor boys) by exploiting cross-sectional variation in PISA test scores from 39 countries - the majority of which belong to the OECD - at a given year (2003). Using five waves of PISA data spanning the period 2003-2015 and exploiting variation both across- and within-countries, we find that the positive association between the female-male gender gap in math test scores and several measures of gender equality vanishes in OECD countries once we account for country fixed effects. Interestingly, our analysis also uncovers a positive and statistically significant association between the math gender gap and several gender equality indicators for countries in the bottom quartile of per capita GDP. This association is robust to controlling for country-level time-invariant unobserved heterogeneity. [ABSTRACT FROM AUTHOR]