低温供热堆——助力冬季供暖蓝天保卫战

2023年11月25日,我国首个跨地级市核能供热工程-国家电投“暖核一号”三期核能供热项目正式投运,位于黄海之滨的山东海阳核电站在给烟台海阳市供暖的同时,供暖区域直达威海乳山市,实现了零碳热源的跨区域互通共享。核能供热,并非一项新技术,在世界范围内有着广泛、成熟的应用。目前,全世界400余台在运核反应堆中有超过1/10的机组已实现热电联供,且已累计安全运行约1000堆/年。目前我国已投运的核能商用供热项目均采用抽汽供暖技术,就是从核电厂汽轮机抽取部分发过电的蒸汽作为热源,将热量送给热力公司再经市政供热网络传递给终端用户。

A Phase Shift Demodulation Technique： Verification and Application in Fluorescence Phase Based Oxygen Sensors

A phase shift demodulation technique based on subtraction capable of measuring 0.03 phase degree limit between sinusoidal signals is presented in this paper. A self-gain module and a practical subtracter act the kernel parts of the phase shift demodulation system. Electric signals in different phases are used to verify the performance of the system. In addition, a new designed optical source, laser fiber differential source （LFDS）, capable of generating mini phase is used to further verify the system reliability. R-square of 0.99997 in electric signals and R-square of 0.99877 in LFDS are achieved, and 0.03 degree measurement limit is realized in experiments. Furthermore, the phase shift demodulation system is applied to the fluorescence phase based oxygen sensors to realize the fundamental function. The experimental results reveal that a good repetition and better than 0.02% oxygen concentration measurement accuracy are realized. In addition, the phase shift demodulation system can be easily integrated to other applications.

SNR Improvement of QEPAS System by Preamplifier Circuit Optimization and Frequency Locked Technique

Preamplifier circuit noise is of great importance in quartz enhanced photoacoustic spectroscopy （QEPAS） system. In this paper, several noise sources are evaluated and discussed in detail. Based on the noise characteristics, the corresponding noise reduction method is proposed. In addition, a frequency locked technique is introduced to further optimize the QEPAS system noise and improve signal, which achieves a better performance than the conventional frequency scan method. As a result, the signal-to-noise ratio （SNR） could be increased 14 times by utilizing frequency locked technique and numerical averaging technique in the QEPAS system for water vapor detection.

A Portable Analog Lock-In Amplifier for Accurate Phase Measurement and Application in High-Precision Optical Oxygen Concentration Detection

A portable analog lock-in amplifier capable of accurate phase detection is proposed in this paper. The proposed lock-in amplifier, which uses the dual-channel orthometric signals as the references to build the xy coordinate system, can detect the relative phase between the input and x-axis based on trigonometric function. The sensitivity of the phase measurement reaches 0.014degree, and a detection precision of 0.1 degree is achieved. At the same time, the performance of the lock-in amplifier is verified in the high precision optical oxygen concentration detection. Experimental results reveal that the portable analog lock-in amplifier is accurate for phase detection applications. In the oxygen sensing experiments, 0.058% oxygen concentration resulted in 0.1 degree phase shift detected by the lock-in amplifier precisely. In addition, the lock-in amplifier is small and economical compared with the commercial lock-in equipments, so it can be easily integrated in many portable devices for industrial applications.

Comparing imaging capabilities of spectral domain and swept source optical coherence tomography angiography in healthy subjects and central serous retinopathy

Background:There are two forms of system implementation of optical coherence tomography angiography(OCTA)in ophthalmic imaging,i.e.,spectral domain(SD-)and swept source OCTA(SS-OCTA).The purpose of this paper is to compare the SD-OCTA and SS-OCTA for elucidating structural and vascular features associated with central serous retinopathy(CSR),and to evaluate the effects of CSR on SD-and SS-OCTA’s imaging capabilities.Methods:Normal subjects and CSR patients were imaged by SD-and SS-OCTA using 3×3 mm and 6×6 mm scan patterns.OCT signal strengths at the superficial retina,deep retina,Sattler’s layer and Haller’s layer were used to compare the ability of SD-and SS-OCTA to image structural features.In addition,the ability to acquire angiograms were discussed by evaluating retinal vessel density.Central serous volume(CSV)was measured and it was correlated with difference in signal strengths(ΔS)between two OCTA devices.Results:Seven normal eyes and seven diseased eyes were recruited.Results showed no significant differences between SD-and SS-OCT in detecting structural features of the retinal layer according to the paired t-test.However,when imaging the Sattler’s layer for normal eyes,a significant difference is found between SD-and SS-OCT(p<0.0001 for 3×3 mm scan,and p=0.0002 for 6×6 mm);while for CSR eyes,the corresponding values were p<0.0001 and p=0.0003,respectively.At Haller’s layer for normal eyes,the corresponding values were p=0.0004 and p=0.0014;and for CSR eyes,p=0.0004 and p<0.0001,respectively.A strong correlation betweenΔS and CSV was observed in the Sattler’s layer(3×3 mm–p=0.0031 and R^(2)=0.951;6×6 mm–p=0.0075 and R^(2)=0.911)and Haller’s layer(3×3 mm–p=0.0026 and R^(2)=0.955;6×6 mm–p=0.0013 and R^(2)=0.972).Conclusions:The results suggest no differences between SD-and SS-OCTA for imaging the retinal layers however,when imaging beyond retinal layers,SS-OCTA appears advantageous in detecting returning signals.In CSR cases,the CSV may have an impact on sub-CSR tissue imaging and appears to have more impact on SD-than SS-OCTA.