Compressive nano-FTIR chemical mapping

Nano-Fourier-transform infrared spectroscopy (nano-FTIR) combines infrared spectroscopy with scanning probe microscopy (SPM) techniques and enables spectroscopic imaging of molecular and electronic properties of matter at nanometer spatial resolution. The spectroscopic imaging can be used to derive chemical mappings, i.e., the spatial distribution of concentrations of the species contained in a given sample. However, due to the sequential scanning principle underlying SPM, recording the complete spectrum over a large spatial area leads to long measurement times. Furthermore, the acquired spectrum often contains additional signals from species and lineshape effects that are not explicitly accounted for. A compressive chemical mapping approach is proposed for undersampled nano-FTIR data that utilizes sparsity of these additional signals in the spectral domain. The approach combines a projection technique with standard compressed sensing, followed by a spatially regularized regression. Using real nano-FTIR measurements superimposed by simulated interferograms representing the chemical mapping of the contained species, it is demonstrated that the proposed procedure performs well even in cases in which the simulated interferograms and the sparse additional signals exhibit a strong spectral overlap.

Perception Measurement of City Brand Archetype in Xiamen, Zhangzhou, and Quanzhou-Based on Projection Method Analysis

City branding is the most concentrated embodiment of city image and the most valuable intangible asset of a city. City branding can attract investors, talents, tourists, and the public’s attention to the city, as well as enhance the competitiveness of the city and bring greater economic benefits and growth potential to the city. Past studies in the context of city branding systematically focus on the development, shaping and communication. Little is known on the combination of city branding and brand archetypes. The projection technique is applied for this research. The objective of this research is to explore the archetypes of city brand based on the Twelve Chinese Cultural Archetypes theory, and takes Xiamen, Zhangzhou, and Quanzhou as the examples. The research reveals that Xiamen belongs to the archetype of “Beauty”, Zhangzhou is close to the archetype of “Neighborhood”, and Quanzhou belongs to the archetype of “Benevolent”.

A CHEBYSHEV PROJECTION METHOD FOR SOLVING SHALLOW-WATER EQUATIONS

The aims of this paper is to propose a numerical approach to simulate water flows in a 2D shallow medium. We consider the 2D Shallow water equations following the velocity-denivelation formulation. We solve these equations by a projection technique using a $\mathbb{P}_{N,M}$-type Chebyshev spectral approach which uses the Chebyshev-Gauss-Lobatto collocation points.

Radiographic optimization of the lateral position of the knee joint aided by CT images and the maximum intensity projection technique

Background Standard lateral knee-joint X-ray images are crucial for the accurate diagnosis and treatment of many knee-joint-related conditions. However, it is difficult to obtain standard lateral knee-joint X-ray images in the current knee-joint lateral radiography position. Purpose To optimize the lateral position of knee joint for radiography aided by computed tomography (CT) images and the maximum intensity projection technique. Materials and methods One hundred cases of anteroposterior and lateral radiographs of knee joints were included. Of these, 50 cases were for lateral radiography in conventional position, and the other 50 cases were for lateral radiography in optimized position. The optimized position was acquired by a retrospective analysis of one hundred cases of knee-joint CT images. The quality of the X-ray images in optimized group was compared with those in conventional group. The data were statistically analyzed using the Mann–Whitney U test. Results There were differences in the optimized position between males and females. The posterior condyles of the femoral epiphysis in optimized group were in perfect superimposition for most patients. However, the ones in conventional group were not. The average quality score of the lateral knee-joint X-ray images in optimized position was 3.76 ± 0.98, which is much higher than the 1.84 ± 1.15 score in conventional position. Moreover, the difference in the average quality score was statistically significant (P < 0.05). Conclusion Optimization of the lateral position of knee joint for radiography is possible with the aid of CT images and the maximum intensity projection technique.

Impact of Wave-Vortical Interactions on Oceanic Submesoscale Lateral Dispersion

Submesoscale lateral transport of Lagrangian particles in pycnocline conditions is investigated by means of idealized numerical simulations with reduced-interaction models. Using a projection technique, the models are formulated in terms of wave-mode and vortical-mode nonlinear interactions, and they range in complexity from full Boussinesq to waves-only and vortical-modes-only (QG) models. We find that, on these scales, most of the dispersion is done by vortical motions, but waves cannot be discounted because they play an important, albeit indirect, role. In particular, we show that waves are instrumental in filling out the spectra of vortical-mode energy at smaller scales through non-resonant vortex-wave-wave triad interactions. We demonstrate that a richer spectrum of vortical modes in the presence of waves enhances the effective lateral diffusivity, compared to QG. Waves also transfer energy upscale to vertically sheared horizontal flows which are a key ingredient for internal-wave shear dispersion. In the waves-only model, the dispersion rate is an order of magnitude smaller and is attributed entirely to internal-wave shear dispersion.

Limited-angle weighted ultrasonic back-projection imaging with ART algorithm imaging

Ultrasonic through-transmission data processed using the back-projection algorithm offers depth and lateral information about a defect beyond the capabilities of current through-transmission techniques. This technique was trialled on a carbon steel block containing side-drilled holes. Imaging artefacts can arise from the use of the backprojection algorithm, due to applying a weighting of one to each pixel, irrespective of how much of the pixel is intersected by the beam. Noise can also occur within the image where there are few intersections of the pixels made. This is seen at the edges of the image. In this paper, a novel back-projection technique utilises the weighting of pixels, dependent on the normalised weight of the beam that intersects them, to reduce any artefacts that occurred previously due to the backprojection algorithm. This paper also explores the use of the algebraic reconstruction technique (ART) algorithm for noise removal, thus increasing the sharpness of the defect.