Model-based force-driven nonrigid motion recovery from sequences of range images without point correspondences

In this article we propose a new method for accurate nonrigid motion analysis when point correspondence data is not available. Nonlinear finite element models are constructed by integrating range data and prior knowledge about an object's properties. The motion sequence is recovered given an initial alignment of the model with the first frame of the sequence. The main idea of the method is to find the forces that are responsible for the motion or shape deformation of the given object. The task is broken into subtasks of finding the forces for each frame. Both absolute values and directions of these forces are taken into consideration and iteratively varied not only for each frame, but also between the frames. Experimental results demonstrate the success of the proposed algorithm. The method is applied to man-made elastic materials and human hand modeling. It allows for recovery of single and multiple forces using restricted (elastic-articulated) and completely unrestricted (elastic) models. Our work demonstrates the possibility of accurate nonrigid motion analysis and force recovery from range image sequences containing nonrigid objects and large motion without interframe point correspondences.     

Analysis and enhancement of human–machine interfaces using a joystick controller

This article deals with performance evaluation of human operations in point‐to‐point displacement tasks using a joystick. Analysis of operator outputs during an experimental task revealed a pattern of partially overlapping submovements with predictable velocity characteristics and forms. A velocity‐dependent gain control added to the joystick–cursor interface improved performance when compared to a conventional linear transformation. This control algorithm can be recommended for many similar human–machine interfaces. A specific performance evaluation was applied to estimate the characteristics of different remote control designs. This approach can be used for evaluating human–machine systems. © 2000 John Wiley & Sons, Inc.     

SANS analysis of aqueous dispersions of Eu- and Gd-grafted nanodiamond particles

Abstract

The structure of detonation nanodiamond aqueous dispersions grafted by europium or gadolinium atoms was investigated by small-angle neutron scattering over a wide size scale from 1 to 3000?nm. Similar to the previous studies of nanodiamond suspensions, a strong association of the particle into developed aggregates was revealed. While the characteristic aggregate size depends on the modification of the dispersions and varies in a wide interval of 35–1500?nm, the fractal character of clusters of nanodiamond particles (packed in a specialized branched form with a fractal dimension of 2.4) remains unchanged independent of the cluster size. The effect of the aggregate size increase upon grafting is considered as a basis for the stability reduction mechanism at the microstructural level.     

Utilization of Extrinsic Fabry-Perot Interferometers with Spectral Interferometric Interrogation for Microdisplacement Measurement

The paper presents a number of signal processing approaches for the spectral interferometric interrogation of extrinsic Fabry-Perot interferometers (EFPIs). The analysis of attainable microdisplacement resolution is performed and the analytical equations describing the dependence of resolution on parameters of the interrogation setup are derived. The efficiency of the proposed signal processing approaches and the validity of analytical derivations are supported by experiments. The proposed approaches allow the interrogation of up to four multiplexed sensors with attained resolution between 30 pm and 80 pm, up to three times improvement of microdisplacement resolution of a single sensor by means of using the reference interferometer and noise-compensating approach, and ability to register signals with frequencies up to 1 kHz in the case of 1 Hz spectrum acquisition rate. The proposed approaches can be used for various applications, including biomedical, industrial inspection, and others, amongst the microdisplacement measurement.     

Synergistic effect of metal components of the low-loaded Pt-Ni-Cr/C catalyst in the bicyclohexyl dehydrogenation reaction

The problem of hydrogen storage in liquid organic hydrogen carriers is not only the choice of an appropriate organic substrate, but the development of a selective and active catalyst containing as low as possible noble metals. A synergistic effect of increasing conversion and selectivity in bicyclohexyl dehydrogenation to biphenyl on trimetallic Pt-Ni-Cr/C catalysts with an extremely low Pt loading (0.1 wt %), compared with bimetallic Ni-Cr/C and Pt/Ni/C systems, due to the supporting of platinum on nickel-chromium nanoparticles was established for the first time. The TOF values (mmol (H₂)/g_Pt min) for hydrogen evolution under conditions of the reaction of bicyclohexyl dehydrogenation (320 °C, 0.1 MPa) on Pt supported onto a Ni-Cr/С composite exceed by two orders of magnitude the values found for the two-component catalysts. The maximum amount of the evolved hydrogen correlates to the selectivity of the complete dehydrogenation of bicyclohexyl into biphenyl on the Pt-Ni-Cr/C catalyst. The formation of a Ni-Cr solid substitution solution in a Ni-Cr composite deposited on a carbon carrier is shown by magnetometry, XRD, and TEM methods.     

Scouting around 1,2,3,4-Tetrahydrochromeno[3,2-c]pyridin-10-ones for Single- and Multitarget Ligands Directed towards Relevant Alzheimer's Targets

A number of 1,2,3,4-tetrahydrochromeno[3,2-c]pyridin-10-one derivatives have been synthesized and screened against different targets involved in the onset and progression of Alzheimer's disease (AD), such as acetyl- and butyrylcholinesterase (AChE and BChE), monoamine oxidases A and B (MAO A and B), aggregation of β-amyloid (Aβ) and reactive oxygen species (ROS) production. Derivatives 1 c , 3 b , 4 and 5 a showed multifaceted profiles of promising anti-AD features and returned well-balanced multitargeting inhibitory activities. Moreover, compound 1 f , a potent and selective human MAO B inhibitor (IC₅₀=0.89 μM), proved to be a safe neuroprotectant in a human neuroblastoma cell line (SH-SY5Y) by improving viability impaired by Aβ_1–42 and pro-oxidant insult. Furthermore, structure–activity relationships (SARs) and docking models were derived in order to assist further hit-to-lead optimization stage.     

Ferroelectric liquid crystals: development of materials and fast electrooptical elements for non-display applications

A brief overview is presented describing the development of ferroelectric liquid crystal materials revealing the electroclinic and DHF (deformed helix ferroelectric) properties and electrooptical elements utilizing these materials.     

On the characterization of sampled-data controllers in the lifted domain

In this paper, we address sampled-data control problems on which the sampling and hold devices are not fixed before-hand, but are chosen as part of the design process. The idea is to apply the lifting transformation to the plant and then characterize the set of generalized sampled-data controllers, i.e., those that can be implemented as the cascade of a generalized sampler, a discrete-time controller and a generalized hold. We argue that our approach offers significant advantages over previous works, and will illustrate this by considering three applications: the input/output stabilization by generalized sampled-data controllers, the solution of the H_∞ optimal control problem and the combination of analog and digital controllers.     

New method for simultaneous measurement of viscosity,density and surface tension of metallic melts at high temperatures

A new method for determination of the viscosity of metallic melts based on the measurement of the velocity of gas bubbles in the melt, is developed. Gas bubbles are produced at known depth through a capillary tube. The time needed by the bubble to reach the surface of the melt is measured with the help of a laser beam. The method is tested with reference metals (Sn, Pb, Cu). The results show that there is a large dependence of the bubble velocity on the viscosity although the diameter of the bubbles is large. The recorded pressure curve in the capillary tube during the bubble formation allows the measurement of the surface tension and the density of the metallic melt to be determined by using the method of the maximum bubble pressure.     

Physical simulation of meteoroid and space debris particles influence on spacecraft construction elements

Three methods of physical simulation of collision with barriers of meteoroid particles and space debris are given. The direct method is to accelerate a model particle by means of a gun or a cumulative device. The method of collision simulation by the barrier splinters when the barrier is broken through with a high-speed steel particle, accelerated as before. The method of hydrosimulation is to simulate the particle and the barrier by means of liquid substances. Theoretical foundation of hydrosimulation is given and the results of compairing the crater dimensions obtained by the impact of liquid and solid pairs are discussed. The boundaries of hydrosimulation of high-speed impact according to velocities for solid impact pairs are V = 2 – 12 km/sec and the dimensions ratio are r /r < 3.