Design, fabrication, and characterization of a single-polarization single-mode flexible hollow waveguide for low loss millimeter wave propagation.

A flexible metallic waveguide with elliptical core that achieves single-polarization single-mode (SPSM) propagation at millimeter wave was designed, fabricated, and characterized. In order to achieve SPSM propagation, optimization of the lengths of major/minor axes of elliptical core was conducted to cut off one of the two orthogonally polarized fundamental modes and all high-order modes. A one-meter long hollow elliptical waveguide (HEW) with major/minor axis length of 1.5/2.7 mm was fabricated. The substrate tube was a flexible elliptical polycarbonate (PC) tube, which was fabricated through glass-draw technique. Silver film was then coated on the inner surface of the tube. Simulation results show that the 1.5/2.7 mm HEW maintains SPSM propagation in the frequency band from 66.5 to 114 GHz. The SPSM operation was experimentally discussed in detail at 100 GHz. The measured loss of 2.58 dB/m and the output polarization ratio of 99.9% was obtained after propagating one meter. Furthermore, the waveguide was robust to bending and twisting. The additional loss was as small as 0.2 dB/m even when the waveguide was coiled into a circle. The potential application of HEWs as polarizers was demonstrated by using a 10 cm long waveguide for polarization detection and extinction ratio of 22.3 dB was achieved at 100 GHz.

Transmission and imaging characteristics of flexible gradually tapered waveguide at 0.3 THz.

Flexible gradually tapered metal waveguides (GTMWs) are fabricated by an inner plating silver film in a polycarbonate (PC) capillary for the transmission and imaging at 0.3 THz. It was demonstrated theoretically and experimentally that GTMWs have lower transmission losses and smaller additional losses of bending, comparing with thin constant bore metal waveguides (CBMWs). Measured losses of 1.95 dB and 2.45 dB were obtained for a 1 m long GTMW with bore size varying from 2.6 mm to 1.6 mm under straight and one circle bending configuration. Measured losses were 4.48 dB/m and 7.78 dB/m for 1.6 mm bore CBMW under the same straight and bend configurations. Owing to higher energy concentration at the output, a larger penetration ability of output wave can be achieved by GTMW, which is beneficial for imaging application. A scanning imaging system was established using fabricated waveguides as the probes. Measured results show that the air slits of the order of wavelength can be clearly distinguished. An imaging system with a GTMW probe also has better performances due to lower bending loss and improved coupling efficiency.

The Impact Imposed by Brand Elements of Enterprises on the Purchase Intention of Consumers-With Experience Value Taken as the Intermediary Variable.

Against the backdrop of China's current dual-circulation paradigm, consumers have experienced the transition of their demands for products from price-driven needs to brand-driven needs. On the one hand, improving the value of consumer experience during brand building can enhance the exchanges and interactions between brands and consumers, facilitating the co-creation of value. On the other hand, the improvement of consumer experience can continuously strengthen the internal power of the construction of enterprise brand elements, and promote consumer-brand identity so as to constantly improve consumer purchase intention. In this study, we have taken consumers from the B2C market as the survey group while innovatively studying the impact imposed by brand elements on the purchase intention of consumers based on the experience value. In addition, we have established the theoretical framework of brand elements-experience value-consumers' purchase intention based on our analysis of the relationship between the aforementioned three factors. Through empirical research, we have elaborated on whether brand elements can improve consumers' purchase intention and whether the experience value can play an intermediary role. The research findings indicate that (1) the three dimensions of brand elements, namely, brand personality, brand value, and brand culture, can impose a significant positive impact on the purchase intention of consumers and experience value; (2) the specific parts of the experience value, namely, functional value, emotional value, social value, and service value, can impose a significant positive impact on the purchase intention of consumers; and (3) experience value can play an intermediary effect to some extent while brand elements influence the purchase intention of consumers.

Learned regularization for image reconstruction in sparse-view photoacoustic tomography.

Constrained data acquisitions, such as sparse view measurements, are sometimes used in photoacoustic computed tomography (PACT) to accelerate data acquisition. However, it is challenging to reconstruct high-quality images under such scenarios. Iterative image reconstruction with regularization is a typical choice to solve this problem but it suffers from image artifacts. In this paper, we present a learned regularization method to suppress image artifacts in model-based iterative reconstruction in sparse view PACT. A lightweight dual-path network is designed to learn regularization features from both the data and the image domains. The network is trained and tested on both simulation and in vivo datasets and compared with other methods such as Tikhonov regularization, total variation regularization, and a U-Net based post-processing approach. Results show that although the learned regularization network possesses a size of only 0.15% of a U-Net, it outperforms other methods and converges after as few as five iterations, which takes less than one-third of the time of conventional methods. Moreover, the proposed reconstruction method incorporates the physical model of photoacoustic imaging and explores structural information from training datasets. The integration of deep learning with a physical model can potentially achieve improved imaging performance in practice.

1ß,10α:4ß,5α-Diep-oxy-7αH-germacran-6ß-ol monohydrate.

In the title compound, C(15)H(26)O(3)·H(2)O, a sesquiterpenoid mol-ecule with a germacrene backbone that contains two epoxide groups and one hydroxyl group. Inter-molecular O-H⋯O hydrogen bonds between the ep-oxy groups and solvent water mol-ecules give rise to an infinite three-dimensional supra-molecular structure.

The configuration of DMD and the maximum intensity projection method for improving contrast in DMD-based confocal microscope.

In this article, an operation strategy of digital micromirror device (DMD) and the maximum intensity projection (MIP) image processing method are proposed to improve the contrast of images in confocal microscopy. First, the configuration of DMD is demonstrated and the effect of scanning unit size on image performance is analyzed. Then, the image processing method MIP is applied. According to the MIP method, only the maximum intensity projection point of the same pixel is chosen from every image, and the maximum intensity projection point exactly corresponds to the positon where mirror is at "on" position during the scanning process in DMD-based confocal microscope system,. Thus, high contrast of images can be achieved by using MIP. Finally, experiments are conducted to verify imaging performance by changing the parameter of scanning unit size and applying a MIP image processing technique. The results show that DMD scanning unit size and MIP image processing techniques play important roles in improving image contrast. Smaller scanning unit size of DMD improves axial contrast but greatly decreases the signal to noise ratio, which thus leads to reduced image contrast. Larger scanning unit size produces a better signal to noise ratio, thus better image contrast. However, a large S will sacrifice the processing time. Therefore, DMD scanning unit size should be smaller on the premise that image contrast can be satisfied. RESEARCH HIGHLIGHTS: Effect of DMD scanning unit size setting on image contrast is analyzed and verified. The maximum intensity projection (MIP) is investigated to improve the image contrast. Experiments are conducted to verify the enhancement of the image contrast.