A fast experimental beam hardening correction method for accurate bone mineral measurements in 3D μCT imaging system

Bone mineral density plays an important role in the determination of bone strength and fracture risks. Consequently, it is very important to obtain accurate bone mineral density measurements. The microcomputerized tomography system provides 3D information about the architectural properties of bone. Quantitative analysis accuracy is decreased by the presence of artefacts in the reconstructed images, mainly due to beam hardening artefacts (such as cupping artefacts). In this paper, we introduced a new beam hardening correction method based on a postreconstruction technique performed with the use of off‐line water and bone linearization curves experimentally calculated aiming to take into account the nonhomogeneity in the scanned animal. In order to evaluate the mass correction rate, calibration line has been carried out to convert the reconstructed linear attenuation coefficient into bone masses. The presented correction method was then applied on a multimaterial cylindrical phantom and on mouse skeleton images. Mass correction rate up to 18% between uncorrected and corrected images were obtained as well as a remarkable improvement of a calculated mouse femur mass has been noticed. Results were also compared to those obtained when using the simple water linearization technique which does not take into account the nonhomogeneity in the object.     

Design as Research

This article explores how design-build programs are moving beyond the goals of hands-on learning and community service to engage in "research-driven" design-build. These programs demonstrate how the design-build studio can serve as a base for the synthesis, integration, and transformation of knowledge through teaching and project execution.     

BEYOND MOBILITY:THE LIMITS OF LIBERAL URBAN POLICY

ABSTRACT: Liberalism remains the dominant philosophical perspective underlying the development of urban public policy in the United States. At the heart of Liberal Urban Policy lies a Mobility Paradigm, which is marked by a strong emphasis on facilitating population movement as a means of addressing urban social problems. In this paper, I explicate the nature of this Mobility Paradigm across four key urban policy goals and then develop a critique of it. In its place, I offer one alternative—a Placemaking Paradigm—and discuss its contrasting conceptual attributes and policy implications. The Placemaking Paradigm points toward the nascent development of a Critical Urban Policy, which stands as an insurgent normative and empirical challenge to hitherto liberal dominance.     

Comments on ‘The phenomenon of homeopathic instability in dynamical systems’

Less restrictive sufficiency conditions on system parameters are developed for the existence of homeopathic instability in the class of dynamical systems considered by Johnson. With these conditions, the results are consistent with the earlier work of Youla el at., in particular in terms of the pole-zero interpretation of the sufficiency conditions. A typographical error in the work by Johnson is also noted.     

OSL—optimal single-loop guide paths for AGVS

This study deals with the Automated Guided Vehicle System guide path design problem. We suggest a single closed loop guide path layout configuration as an alternative to conventional but more complex guide path designs. The benefits of using a simple guide path versus more complicated guide paths are discussed. A procedure for designing an optimal single loop guide path for a given facility layout is presented. Finally, the single loop's throughput performance is tested and compared to that of a more complex guide path.     

DIRECT REDUCTION OF MIXED MAGNETITE AND COAL PELLETS USING INDUCTION HEATING

A low-temperature process for iron-making, using mixed pellets of magnetite and domestic coal with an organic binder was investigated. Reduction tests performed in an induction furnace resulted in a product direct reduced iron (DRI) containing 75–80% metallic iron. The coal energy consumption of 23.71?GJ/ton DRI compares favorably with current DRI processes, although the total energy consumption of 33.65?GJ/ton is relatively high for iron-making. The use of low-grade coal as a reductant may improve the economics of the process as high-grade coking coal supplies dwindle worldwide.     

New class of control laws for robotic manipulators Part 1. Non–adaptive case

A new class of exponentially stabilizing control laws for joint level control of robot arms is introduced. It has recently been recognized that the non-linear dynamics associated with robotic manipulators have certain inherent passivity properties. More specifically, the derivation of the robotic dynamic equations from Hamilton's principle gives rise to natural Lyapunov functions for control design based on total energy considerations. Through a slight modification of the energy Lyapunov function and the use of a convenient lemma to handle third–order terms in the Lyapunov function derivatives, closed–loop exponential stability for both the set point and tracking control problem is demonstrated. In one new design, the nonlinear terms are decoupled from real-time measurements which completely removes the requirement for on–line computation of non–linear terms in the controller implementation. In general, the new class of control laws offers alternatives to the more conventional computed torque method, providing trade–offs between computation and convergence properties. Furthermore, these control laws have the unique feature that they can be adapted in a very simple fashion to achieve asymptotically stable adaptive control.     

INFORMATION THEORETIC APPROACH TO SECURE LSFR CIPHERS

To break a normal LFSR cipher, a cryptanalyst needs only 2n bits of corresponding plain and ciphertext, where n is the number of stages of the shift register.[l] In this paper, a method of substituting completely random characters into the ciphertext and therefore preventing the encipherment of a full 2n-length sequence (under its proper key) will be discussed. Due to the high redundancy of English, a cipher containing several completely random characters will still be readable.     

Retrodiction as a tool for micromaser field measurements

We use retrodictive quantum theory to describe cavity field measurements by successive atomic detections in the micromaser. We calculate the state of the micromaser cavity field prior to detection of sequences of atoms in either the excited or ground state, for atoms that are initially prepared in the excited state. This provides the POM elements, which describe such sequences of measurements.     

Quantifying data for group technology with weighted fuzzy features

The high potential of using group technology in manufacturing has attracted the interest of both practitioners and researchers. Group technology is based on clustering parts which have similar features. Very often it is very hard to quantify successfully data regarding these features. This is because in many real applications features are fuzzy. This paper identifies two types of fuzzy features: qualitative features, and quantitative ones with subjective meaning. The paper presents a methodology for quantifying the data that refer to the fuzzy features. The proposed methodology deals with crisp and fuzzy data in a unified manner. Finally, some clustering approaches which process the quantified features are also discussed