Weighted thin-plate spline image denoising

This note aims to present new denoising method based on thin-plate splines (TPS). The proposed approach is based on the general TPS denoising Berman [2], however, its unfavorable smoothing of edges and details is suppressed by introduction of a weighting approach applied locally. The performance of the method is shown and compared to the original TPS denoising.     

Stress dependence of sensitivity of fluxgate sensor

This paper presents results of investigation of the stress sensitivity of the fluxgate sensor with amorphous alloy (CoFe)₈₉(MnMoSiB)₁₁ (Vitrovac 6150F) ring core. Stress was applied in two directions: perpendicularly to the flux density in the ring core or in the direction of diameter of the ring. The influence of mechanical stress from the external forces on magnetic properties of this ring core was measured. Then results of this testing were used in computer simulation of the influence of the stress on the output signal of the fluxgate sensor.     

Anomalous Excess Heat Capacities of Ethanol + Alkane Mixtures

A thermodynamic study at atmospheric pressure on the ethanol + n-dodecane and ethanol + n-tridecane binary systems near their liquid-liquid critical points has been carried out. To this end, densities and speeds of sound were determined in the temperature range from 288.15 to 308.15 K, whereas differential scanning calorimetry was used to obtain isobaric heat capacities per unit volume from 288.15 to 303.15 K as well as liquid-liquid equilibrium curves. All these results for the mentioned properties were obtained over the complete composition range. They were used to obtain molar volumes, isentropic compressibilities, isobaric thermal expansivities, isothermal compressibilities, isochoric heat capacities, and the excess quantities of all these properties. An untypical behavior of the excess heat capacities at the lowest measuring temperatures resulting from the critical behavior of the isobaric heat capacity is observed. No clear anomalies for the excess volumetric properties are detected.     

Quantitative non-destructive characterization of damage in graphite-epoxy composites

We investigated the effect of controlled damage on the residual strength, failure mechanism and acoustic emission (AE) activity of graphite epoxy composites. The controlled damage was introduced by indenting unidirectional tensile specimens using a hardness machine with a diamond indentor. The specimens were loaded parallel to the fiber direction. The damage progression mechanisms operating upon subsequent loading and the failure modes were found to be different for sound and indented specimens. The difference in mechanical behavior affected also the AE, as displayed by the statistical moments of the peak amplitude distribution. Specifically, the variation of moment values with stress level were found to be different for the two groups. This difference can be used to sort sound from defective material during loading. In addition, this approach can in future be used as a means to ratify the soundness of structures, if a reliable database can be generated.     

Structural Insights into Iron Ions Accumulation in Dps Nanocage

Dps (DNA-binding protein from starved cells) is well known for the structural protection of bacterial DNA by the formation of highly ordered intracellular assemblies under stress conditions. Moreover, this ferritin-like protein can perform fast oxidation of ferrous ions and subsequently accumulate clusters of ferric ions in its nanocages, thus providing the bacterium with physical and chemical protection. Here, cryo-electron microscopy was used to study the accumulation of iron ions in the nanocage of a Dps protein from Escherichia coli. We demonstrate that Fe²⁺ concentration in the solution and incubation time have an insignificant effect on the volume and the morphology of iron minerals formed in Dps nanocages. However, an increase in the Fe²⁺ level leads to an increase in the proportion of larger clusters and the clusters themselves are composed of discrete ~1–1.5 nm subunits.     

On‐Chip Magnetic Platform for Single‐Particle Manipulation with Integrated Electrical Feedback

Methods for the manipulation of single magnetic particles have become very interesting, in particular for in vitro biological studies. Most of these studies require an external microscope to provide the operator with feedback for controlling the particle motion, thus preventing the use of magnetic particles in high‐throughput experiments. In this paper, a simple and compact system with integrated electrical feedback is presented, implementing in the very same device both the manipulation and detection of the transit of single particles. The proposed platform is based on zig‐zag shaped magnetic nanostructures, where transverse magnetic domain walls are pinned at the corners and attract magnetic particles in suspension. By applying suitable external magnetic fields, the domain walls move to the nearest corner, thus causing the step by step displacement of the particles along the nanostructure. The very same structure is also employed for detecting the bead transit. Indeed, the presence of the magnetic particle in suspension over the domain wall affects the depinning field required for its displacement. This characteristic field can be monitored through anisotropic magnetoresistance measurements, thus implementing an integrated electrical feedback of the bead transit. In particular, the individual manipulation and detection of single 1‐μm sized beads is demonstrated.     

Frequency-based underwater terrain segmentation

A method for segmenting three-dimensional data of underwater unstructured terrains is presented. The three-dimensional point clouds are converted to two-dimensional elevation maps and analyzed for segmentation in the frequency domain. The lower frequency components represent the slower varying undulations of the underlying ground. The cut-off frequency, below which the frequency components form the ground surface, is determined automatically using peak detection. The user can also specify a maximum admissible size of objects to drive the automatic detection of the cut-off frequency. The points above the estimated ground surface are clustered via standard proximity clustering to form object segments. The precision of the segmentation is compared against ground truth hand labelled data acquired by a stereo camera pair and a structured light sensor. It is also evaluated for registration error when the extracted segments are used for sub-map alignment. The proposed approach is compared to three point cloud based and two image based segmentation algorithms. The results show that the approach is applicable to a range of different terrains and is able to generate features useful for navigation.     

Design and fabrication of ridge waveguide folded-cavity in-planesurface-emitting lasers

A 45° angled reactive ion etching combined with an in situ monitoring technique was used to fabricate ridge waveguide folded-cavity in-plane surface-emitting lasers. This laser structure, with two 45°C angle-etched internal total-reflection mirrors and an epitaxially grown distributed Bragg reflector, is very promising for OEIC applications. Laser-structure design and laser fabrication are addressed. A continuous-wave threshold current of 8 mA, the lowest reported in the literature, was achieved on 3-μm-wide, 350-μm long devices     

Thermoelectric Effect Spectroscopy and Photoluminescence of High-Resistivity CdTe:In

Thermoelectric effect spectroscopy and photoluminescence techniques were used to study the defect levels in samples from three crystals of CdTe:In grown by the vertical gradient freeze method. The main goal of the investigation was to study defects, which strongly trap charge carriers or act as recombination centers in order to eliminate them from the technological process. The main difference among detecting and non-detecting samples was the absence of electron traps with a very high capture cross-section and energy 0.6 eV to 0.7 eV, which act as lifetime killers even at low concentrations. Recently published ab initio calculations show a complex of Te antisite and Cd vacancy within this energy range.     

全封闭式压缩机腔体声场的数值分析

全封闭式压缩机腔内强烈的声场反映了主要的壳体激发源以及因之产生的噪声辐射。吸气消音器的振动以及机体和电动机表面的辐射激发了这个声场。在对机体、电机表面、数值解法和与机壳的耦合等做不同几何简化的情况下,本文对腔内声场进行了数值分析。模拟结果得到了实验证实,具有良好的一致性。本模型适用于声能向机壳的传播以及向外部环境辐射时分析各参数的影响。