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We designed a calibration system to characterize the performance of microwave devices at low temperatures. This system comprises an in-situ calibration circuit and an adapted thru-reflect-line calibration algorithm, with which we can transfer the reference ports from room temperature to cryogenic temperature with high precision. We validated the circuit and the algorithm at room temperature with better than 0.9 dB accuracy. In addition, we demonstrated how we can extract the actual S 21 of a 20 dB attenuator and a high pass filter at 20 mK using this calibration system. The calibration bandwidth of this system covers from 4.1 GHz to 18 GHz. The requirement that the phase difference between line and thru be greater than 20°determines the lower frequency limit, and the maximum operational frequency of the microwave switch determines the upper frequency limit. This system can be used for fast and accurate analysis of various cryogenic devices such as filters and amplifiers.

The ultra-supercritical power generation technology with high energy efficiency and low emissions is one of the important ways to solve the current increasingly prominent energy problems in the context of international development requirements for carbon neutrality and the increasingly prominent energy shortage. Because of its excellent resistance to high temperature corrosion and organizational stability, S31042 is commonly employed in the most severe working environment of ultra-supercritical units. Due to its great resistance to high-temperature corrosion and organizational stability, S31042 is commonly employed in the most demanding components of ultra-supercritical units such as high-temperature reheaters and high-temperature superheaters. Various characterisation approaches were employed in this research to reflect the microstructure of S31042 heat-resistant steel in service under various time length conditions, and the hardness of S31042 heat-resistant steel was assessed under the corresponding service conditions. The results showed that the hardness of S31042 increased significantly with increasing service time, from around 160 Hv at the time of non-service to nearly 220 Hv after 75360 hours of service. The continuous distribution of uniformly sized M23C6 phase on the grain boundaries of S31042 developed toward grain coarsening after service, but the precipitation strengthening effect produced by the nanoscale secondary NbCrN phase appearing in the grains was the main reason for the increase of the hardness value of S31042, according to the microstructure of the material.

Ultra-supercritical power generation technology is one of the main solutions to the many contradictory problems of carbon emissions and environmental protection in coal-fired power plants. S31042 austenitic heat-resistant steel has become a typical material for high-temperature components used in ultra-supercritical units because of its good high-temperature creep properties and high-temperature corrosion resistance. In this study, typical characterization techniques such as SEM (Scanning Electron Microscopy), TEM (transmission electron microscopy), and EBSD (Electron Backscattered Diffraction) were used to observe the microstructure of S31042 austenitic heat-resistant steel, while the room-temperature tensile and high-temperature tensile properties of the material were tested under the corresponding conditions. The results show that the grain of S31042 heat-resistant steel after service is the same as that of the non-service samples, which is still twinned austenite. The room-temperature tensile properties and high-temperature tensile properties of S31042 after long service were almost unchanged.

The rapid progress towards scalable quantum processors demands amplifiers with large bandwidths and high saturation powers. For this purpose, we present a broadband flux-pumped Josephson parametric amplifier integrated with an on-chip coplanar waveguide impedance transformer. Our device can be fabricated with simple and straightforward photo-lithography. This device experimentally achieves an operational bandwidth over 600 MHz with a gain above 15 dB, and a high saturation power with quantum-limited noise performance. In addition, the center frequency of this device can be tuned over several hundred megahertz, which in turn broadens the effective operational bandwidth to around 1 GHz.

In recent years, bridge disasters caused by scour have occurred frequently; hence, scour has become one of the most important factors that threatens the safety of wading bridges. Although the research on the local scour around bridge pier has been carried out for many years, there are few research results on the evaluation of scour hazard of built bridge piers and that of unbuilt bridge piers. On the basis of previous research results at home and abroad, this paper systematically analyzes the research results related to the evaluation of local scour of bridge piers in recent decades, including the prediction of scour pit depth, the risk assessment of local scour failure and the prediction of scour depth based on risk theory. In this paper, the trend of local scour evaluation of bridge piers is also discussed.

This paper presents a novel uniaxial microscopic 3D profilometry method using a structured light system with dual-telecentric lenses in micro-scale devices. Specifically, a telecentric lens can produce an orthographic view of an object and provide the exact size of objects in x and y-direction. An electronically focus-tunable lens attached to the projector rapidly and precisely changes the focal plane of the projected structured patterns, a camera captures the structured patterns from the same perspective, and a computational framework analyzes the relationship between captured structure images and the drive current of the electronically focus-tunable lens to obtain depth information for each pixel. By replacing the normal lens with telecentric lenses, the proposed method dodges perspective error and is easier for precision measurement. We developed a shadow-free coaxial 3D shape measurement system with dual telecentric lenses that achieved approximately 5.86 μm spatial resolution and 4.08 μm root-mean-square (RMS) error with a depth range of 1200 μm.

N–B co-doped SiC, as an excellent candidate for white LEDs, were prepared by the physical vapor transport growth method. Doping type and concentrations of fluorescent SiC crystals were examined by Raman spectroscopy and secondary ion mass spectroscopy measurements. The band-to-band excitation mechanism of donor and acceptor pairs (DAPs) luminescence in f-SiC has been clarified based on excitation spectroscopic measurements. The luminescence intensity of DAPs decreases with the increase of excitation source energy due to the absorption when excitation source energy is greater than 3.7 eV. Moreover, the threshold energy and the optimal excitation wavelength did not change with the carrier concentration, while the photoluminescence emission intensity increased with the decrease of carrier concentration. When the excitation power increased from 2 to 44 mW, the luminescence intensity can be well fitted by the power dependence I = aP γ , the higher the B doping concentration, that is, the lower the carrier concentration, the intensity is more sensitive to the excitation power change. At same time, the luminescence peaks of high doping concentration samples shift to the high energy with high excitation power. The shifts and the underlying mechanism have been discussed.