Agile Spectrum Imaging: Programmable Wavelength Modulation for Cameras and Projectors

We advocate the use of quickly‐adjustable, computer‐controlled color spectra in photography, lighting and displays. We present an optical relay system that allows mechanical or electronic color spectrum control and use it to modify a conventional camera and projector. We use a diffraction grating to disperse the rays into different colors, and introduce a mask (or LCD/DMD) in the optical path to modulate the spectrum. We analyze the trade‐offs and limitations of this design, and demonstrate its use in a camera, projector and light source. We propose applications such as adaptive color primaries, metamer detection, scene contrast enhancement, photographing fluorescent objects, and high dynamic range photography using spectrum modulation.     

Maximal versus strong solution to algebraic Riccati equations arising in infinite Markov jump linear systems

We deal with a perturbed algebraic Riccati equation in an infinite dimensional Banach space which appears, for instance, in the optimal control problem for infinite Markov jump linear systems (from now on iMJLS). Infinite or finite here has to do with the state space of the Markov chain being infinite countable or finite (see, e.g., [M.D. Fragoso, J. Baczynski, Optimal control for continuous time LQ—problems with infinite Markov jump parameters, SIAM J. Control Optim. 40(1) (2001) 270–297]). By using a certain concept of stochastic stability (a sort of L₂-stability), we have proved in [J. Baczynski, M.D. Fragoso, Maximal solution to algebraic Riccati equations linked to infinite Markov jump linear systems, Internal Report LNCC, no. 6, 2006] existence (and uniqueness) of maximal solution for this class of equations. As it is noticed in this paper, unlike the finite case (including the linear case), we cannot guarantee anymore that maximal solution is a strong solution in this setting. Via a discussion on the main mathematical hindrance behind this issue, we devise some mild conditions for this implication to hold. Specifically, our main result here is that, under stochastic stability, along with a condition related with convergence in the infinite dimensional scenario, and another one related to spectrum—weaker than spectral continuity—we ensure the maximal solution to be also a strong solution. These conditions hold trivially in the finite case, allowing us to recover the result of strong solution of [C.E. de Souza, M.D. Fragoso, On the existence of maximal solution for generalized algebraic Riccati equations arising in stochastic control, Systems Control Lett. 14 (1990) 233–239] set for MJLS. The issue of whether the convergence condition is restrictive or not is brought to light and, together with some counterexamples, unveil further differences between the finite and the infinite countable case.     

Delineating Boundaries for Imprecise Regions

In geographic information retrieval, queries often name geographic regions that do not have a well-defined boundary, such as “Southern France.” We provide two algorithmic approaches to the problem of computing reasonable boundaries of such regions based on data points that have evidence indicating that they lie either inside or outside the region. Our problem formulation leads to a number of subproblems related to red-blue point separation and minimum-perimeter polygons, many of which we solve algorithmically. We give experimental results from our implementation and a comparison of the two approaches. This research is supported by the EU-IST Project No. IST-2001-35047 (SPIRIT) and by grant WO 758/4-2 of the German Research Foundation (DFG).     

Observed finger behaviour during computer mouse use

Two-button computer mouse users may exhibit sustained, static finger lifting behaviours to prevent inadvertent activations by avoiding finger pressure on the buttons, which leads to prolonged, static finger extensor muscle loading. One hundred graduate students were observed during normal computer work in a university computer facility to qualify and quantify the prevalence of lifted finger behaviours and extended finger postures, as well as wrist/forearm and grip behaviour, during specific mouse activities. The highest prevalences observed were 48% of the students lifted their middle finger during mouse drag activities, and 23% extended their middle finger while moving the mouse. In addition, 98% of the students rested their wrist and forearm (77%) or wrist only (21%) on the workstation surface, and 97% had an extended wrist posture (15 degrees -30 degrees ) when using the mouse. Potential applications of these findings include future computer input device designs to reduce finger lifting behaviour and exposures to risk factors of hand/forearm musculoskeletal pain.     

远大前程——阿尔派“水”与争锋

每年1月,汽车音响行业都会翘首以盼阿尔派音响改装样板车问世。一般,在拉斯维加斯的国际消费类电子产品展览会(CES)上,阿尔派设计人员都会向人们展示其样板车。在过     

碳纤维低音箱制作

时下,石油的价格飚升,经济持续低迷。也许,我们(包括汽车音响发烧友)都需要采取一些砍掉成本的措施。多年来,我决定采取升级改装的汽车。汽车的其余部位拥有大量的碳纤维,我打算使用碳纤维制作低音箱,使之符合配合主题元素。同时,箱体的重量越轻越好。我拿来另一改装车用剩下来的一块12英寸的聚氯乙烯(PVC),用它来包裹箱体。箱体是由6061铝、碳纤维及少许环氧混合制作而成。     

Air damping of high performance resonating micro-mirrors with angular vertical comb-drive actuators

Microsystem Technologies - The maximum scan angle amplitude of resonating micro-mirrors, intended for micro-projection display applications is limited by air damping. Three-dimensional transient...     

Statistical reconstruction and Karhunen–Loève expansion for multiphase random media

Termed as random media, rocks, composites, alloys and many other heterogeneous materials consist of multiple material phases that are randomly distributed through the medium. This paper presents a robust and efficient algorithm for reconstructing random media, which can then be fed into stochastic finite element solvers for statistical response analysis. The new method is based on nonlinear transformation of Gaussian random fields, and the reconstructed media can meet the discrete‐valued marginal probability distribution function and the two‐point correlation function of the reference medium. The new method, which avoids iterative root‐finding computation, is highly efficient and particularly suitable for reconstructing large‐size random media or a large number of samples. Also, benefiting from the high efficiency of the proposed reconstruction scheme, a Karhunen–Loève (KL) representation of the target random medium can be efficiently estimated by projecting the reconstructed samples onto the KL basis. The resulting uncorrelated KL coefficients can be further expressed as functions of independent Gaussian random variables to obtain an approximate Gaussian representation, which is often required in stochastic finite element analysis. Copyright © 2015 John Wiley & Sons, Ltd.     

The SCD – Stem Cell Differentiation ESA Project: Preparatory Work for the Spaceflight Mission

Due to spaceflight, astronauts experience serious, weightlessness-induced bone loss because of an unbalanced process of bone remodeling that involves bone marrow mesenchymal stem cells (BMSCs), as well as osteoblasts, osteocytes, and osteoclasts. The effects of microgravity on osteo-cells have been extensively studied, but it is only recently that consideration has been given to the role of BMSCs. Previous researches indicated that human BMSCs cultured in simulated microgravity (sim-μg) alter their proliferation and differentiation. The spaceflight opportunities for biomedical experiments are rare and suffer from a number of operative constraints that could bias the validity of the experiment itself, but remain a unique opportunity to confirm and explain the effects due to microgravity, that are only partially activated/detectable in simulated conditions. For this reason, we carefully prepared the SCD – STEM CELLS DIFFERENTIATION experiment, selected by the European Space Agency (ESA) and now on the International Space Station (ISS). Here we present the preparatory studies performed on ground to adapt the project to the spaceflight constraints in terms of culture conditions, fixation and storage of human BMSCs in space aiming at satisfying the biological requirements mandatory to retrieve suitable samples for post-flight analyses. We expect to understand better the molecular mechanisms governing human BMSC growth and differentiation hoping to outline new countermeasures against astronaut bone loss.