Cascaded Kalman and particle filters for photogrammetry based gyroscope drift and robot attitude estimation

Based on a cascaded Kalman–Particle Filtering, gyroscope drift and robot attitude estimation method is proposed in this paper. Due to noisy and erroneous measurements of MEMS gyroscope, it is combined with Photogrammetry based vision navigation scenario. Quaternions kinematics and robot angular velocity dynamics with augmented drift dynamics of gyroscope are employed as system state space model. Nonlinear attitude kinematics, drift and robot angular movement dynamics each in 3 dimensions result in a nonlinear high dimensional system. To reduce the complexity, we propose a decomposition of system to cascaded subsystems and then design separate cascaded observers. This design leads to an easier tuning and more precise debugging from the perspective of programming and such a setting is well suited for a cooperative modular system with noticeably reduced computation time. Kalman Filtering (KF) is employed for the linear and Gaussian subsystem consisting of angular velocity and drift dynamics together with gyroscope measurement. The estimated angular velocity is utilized as input of the second Particle Filtering (PF) based observer in two scenarios of stochastic and deterministic inputs. Simulation results are provided to show the efficiency of the proposed method. Moreover, the experimental results based on data from a 3D MEMS IMU and a 3D camera system are used to demonstrate the efficiency of the method.     

Effect of gadolinium ions on the structure and magnetic properties of zinc-borate glasses and glass ceramics

X-ray diffraction (XRD), electron paramagnetic resonance (EPR), and magnetic susceptibility measurements have been employed to investigate the samples from the (Gd₂O₃) _x ·(B₂O₃)_(60−x)·(ZnO)₄₀ (0 ≤ x ≤ 20 mol%) system. The XRD pattern for the prepared samples shows that the vitreous phase is present only for x ≤ 15 mol%. For the samples containing 20 mol% Gd₂O₃ the presence of a unique crystalline phase, GdBO₃, embedded in a vitreous matrix was evidenced. In this case the XRD patterns show the presence of nanometer sized crystals (64 nm) in a glassy matrix. The EPR spectra of the studied samples exhibit three important features with effective g-values of ≈6, 2.8, 2.0 and a weaker feature at g ≈ 4.8. For low Gd₂O₃ contents (x < 3 mol%), the EPR spectra have the typical ‘‘U’’-type shape. For higher contents of Gd₂O₃ (x ≥ 3 mol%), the spectral features are broadened and finally are dominated by a single broad absorption line located at g ≈ 2.0. This broad EPR line is associated to the Gd³⁺ ions present predominantly as clustered species. Magnetic susceptibility data show that for x > 1 mol% the Gd³⁺ ions are present not only as isolated species but also as species coupled through antiferromagnetic exchange interactions.     

Tensile fatigue behaviour of ultra-high performance fibre reinforced concrete (UHPFRC)

The tensile fatigue behaviour of ultra-high performance fibre reinforced concrete (UHPFRC) under constant amplitude fatigue cycles is presented. Three series of uniaxial tensile fatigue tests up to a maximum of 10 million cycles were conducted with the objective to determine the endurance limit of UHPFRC that was supposed to exist for this material. The fatigue tests reveal that an endurance limit exists in all three domains of UHPFRC tensile behaviour at S-ratios ranging from 0.70 to 0.45 with S being the ratio of the maximum fatigue stress to the elastic limit strength of UHPFRC. Rather large variation in local specimen deformations indicates significant stress and deformation redistribution capacity of the UHPFRC bulk material enhancing the fatigue behaviour. The fatigue fracture surface of UHPFRC shows features of the fatigue fracture surfaces of steel, i.e. fatigue crack propagation is identified by a smooth surface while final fracture leads to rather rough surface. Various fatigue damaging mechanisms due to fretting and grinding as well as tribocorrosion are identified.     

��Note on ��Flows induced by a plate moving normal to stagnation-point flow�� by P. D. Weidman and M. A. Sprague (Acta Mech. 219, 219�C229, 2011)��

In a recent paper of Weidman and Sprague (Acta Mech., 2011), the unsteady flows generated by an impermeable infinite flat plate advancing with constant velocity V toward, or receding from an orthogonal (plane or axisymmetric) stagnation-point flow, have been investigated by an exact similarity reduction of the Navier?CStokes equations. It has been shown that in the co-moving reference frame of the plate, the induced flow appears as a steady flow, with an additional term R f??? in the governing equation of the similar stream function f (??). The Reynolds number R involved in this additional term is proportional to the plate velocity V. The present paper shows, however, that with the aid of a simple transformation, the additional term R f??? can be removed from the governing equation, its effect being transferred in the boundary condition for f (??). As a consequence, the unsteady flow problems of Weidman and Sprague reduce to the classical steady stagnation-point flow problems for permeable surfaces with a uniform lateral suction or injection of the fluid, so that the transpiration parameter f (0) coincides with R for the plane and with R/2 for the axisymmetric flow, respectively. The main benefit of this approach is that all the results of the latter well-investigated problems can simply be transcribed for the problems formulated by Weidman and Sprague (Acta Mech, 2011).     

Time dependent behavior of elements combining ultra-high performance fiber reinforced concretes (UHPFRC) and reinforced concrete

Structural elements combining Ultra-High Performance Fiber Reinforced Concretes (UHPFRC) and concrete offer a high potential in view of rehabilitation and modification of existing structures. The investigation of the time-dependent behavior of composite “UHPFRC-concrete” elements is a fundamental step in the determination of durability and serviceability. For this, an experimental program was conducted on large composite “UHPFRC-concrete” beams and a numerical model was validated with the test results. The experimental results and a parametric study performed with the numerical model showed that UHPFRC and normal strength reinforced concrete are compatible in the long-term and that the critical period of composite “UHPFRC-concrete” elements are the first 90 days after the casting of the UHPFRC layer. Thus, the high potential of such composite elements can be exploited also in the long term.     

Localized Synthesis of Iron Oxide Nanowires and Fabrication of High Performance Nanosensors Based on a Single Fe2O3 Nanowire

A composed morphology of iron oxide microstructures covered with very thin nanowires (NWs) with diameter of 15–50 nm has been presented. By oxidizing metallic Fe microparticles at 255 °C for 12 and 24 h, dense iron oxide NW networks bridging prepatterned Au/Cr pads are obtained. X‐ray photoelectron spectroscopy studies reveal formation of α‐Fe₂O₃ and Fe₃O₄ on the surface and it is confirmed by detailed high‐resolution transmission electron microscopy and selected area electron diffraction (SAED) investigations that NWs are single phase α‐Fe₂O₃ and some domains of single phase Fe₃O₄. Localized synthesis of such nano‐ and microparticles directly on sensor platform/structure at 255 °C for 24 h and reoxidation at 650 °C for 0.2–2 h, yield in highly performance and reliable detection of acetone vapor with fast response and recovery times. First nanosensors on a single α‐Fe₂O₃ nanowire are fabricated and studied showing excellent performances and an increase in acetone response by decrease of their diameter was developed. The facile technological approach enables this nanomaterial as candidate for a range of applications in the field of nanoelectronics such as nanosensors and biomedicine devices, especially for breath analysis in the treatment of diabetes patients.     

Automated imaging, identification, and counting of similar cells from digital hologram reconstructions

This paper presents our method, which simultaneously combines automatic imaging, identification, and counting with the acquisition of morphological information for at least 1000 blood cells from several three-dimensional images of the same sample. We started with seeking parameters to differentiate between red blood cells that are similar but different with respect to their development stage, i.e., mature or immature. We highlight that these cells have different diffractive patterns with complementary central intensity distribution in a given plane along the propagation axis. We use the Fresnel approximation to simulate propagation through cells modeled as spheroid-shaped phase objects and to find the cell property that has the dominant influence on this behavior. Starting with images obtained in the reconstruction step of the digital holographic microscopy technique, we developed a code for automated simultaneous individual cell image separation, identification, and counting, even when the cells are partially overlapped on a slide, and accurate measuring of their morphological features. To find the centroids of each cell, we propose a method based on analytical functions applied at threshold intervals. Our procedure separates the mature from the immature red blood cells and from the white blood cells through a decision based on gradient and radius values.     

Determination of phosphorus-, copper-, and zinc-containing human brain proteins by LA-ICPMS and MALDI-FTICR-MS

Human brain proteins containing phosphorus, copper, and zinc were detected directly in protein spots in gels of a human brain sample after separation by two-dimensional gel electrophoresis using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). A powerful laser ablation system with cooled laser ablation chamber was coupled to a double-focusing sector field ICPMS. The separated protein spots in 2D gels were fast screened using the optimized microanalytical LA-ICPMS technique measured at medium mass resolution with a focused laser beam (wavelength, 213 nm; diameter of laser crater, 50 mum; and laser power density, 3 x 10(9) W cm(-2)) with respect to selected three essential elements. Of 176 protein spots in 2D gel from a human brain sample, phosphorus, copper, and zinc were detected in 31, 43, and 49 protein spots, respectively. For the first time, uranium as a naturally occurring radioactive element was found in 20 selected protein spots. The detection limits for P, S, Cu, Zn and U were determined in singular protein spots with 0.0013, 1.29, 0.029, 0.063, and 0.000 01 mg g(-1), respectively. A combination of LA-ICPMS with matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR-MS) was applied for the identification of selected protein spots from human brain protein separated by 2D gel electrophoresis. Combining MALDI-FTICR-MS for the structure analysis of metal- and phosphorus-containing human brain proteins with LA-ICPMS, the direct analysis of heteroelements on separated proteins in 2D gels can be performed. For quantification of analytical LA-ICPMS data, the number of sulfur atoms per protein (and following the sulfur concentration) determined by MALDI-FTICR-MS was used for internal standardization. From the known sulfur concentration in protein, the concentration of other heteroelements was calculated. In addition, the number of phosphorylation and the phosphorylation sites of phosphorylated proteins in the human brain sample detected by LA-ICPMS were determined by MALDI-FTICR-MS. This technique allows the study of posttranslational modifications in human brain proteins.