[en] This work reports on experimental studies that examine the subcooled boiling on the enhanced heat transfer surface of the hypervapotron structure. The experiment was conducted for steady state, subcooled boiling with different heat fluxes (from 50 to 800 kW/m²). Working with a high speed (12,000 frames per second), high fidelity digital camera with variable magnifications (from 1x -25x), subcooled boiling in a single cavity was observed in detail. This research uses the simulant fluid Freon (R134A) instead of prototypic water to model the system performance. A major conclusion of this work is the existence of highly localized vapor production and motion characteristics. The process of bubble coalescence and vapor patch stagnation in the slot is believed to have crucial impact on local critical heat flux (CHF) performance. By approaching CHF conditions, the three wall sides of cavity show visible differences in the thermal behavior. The process of vapor bubble rotation in the cavity is believed to be helpful to enhance energy transfer, as evidenced by an improved wetting condition on the heating surfaces., However, this facilitation of rewetting appears to behave differently on the walls in a single cavity. (authors)

[en] In order to expand the nuclear power in energy and desalination, increase competitiveness in global nuclear power market, many developed countries with strong nuclear energy technology have realized the importance of Small Modular Reactor (SMR) and initiated heavy R and D programs in SMR. The Advanced Small Pressurized Water Reactor (ASPWR) is characterized by great advantages in safety and economy and can be used in remote power grid and replace mid/small size fossil plant economically. This paper reviews the history and current status of SMR and ASPWR, and also discusses the design concept, safety features and other advantages of ASPWR. The purpose of this paper is to provide an overall review of ASPWR technology in western countries, and to promote the R and D in ASPWR in China. (authors)

[en] The fabrication of anodes and active layers by dip-coating in indium tin oxide (ITO)-free polymer solar cells (PSCs) is investigated. A highly conductive poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) layer was used as an anode while a blend film of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) was employed as an active layer. The transmittance and sheet resistance of dip-coated PEDOT:PSS layers prepared with different thickness were studied. These layers were integrated into PSCs. The PSCs with the dip-coated PEDOT:PSS and P3HT:PCBM films exhibited power conversion efficiencies of 3.21% and 3.03% on glass and polyethylene terephthalate substrates, respectively, comparable to those of conventional ITO-based cells. Our research results suggest the feasibility of fabricating PSCs without a traditional spin-coating process and the possibility to substitute the ITO electrodes for conducting polymer films using the facile dip-coating method. - Highlights: • ITO-free polymer solar cells (PSCs) were fabricated by dip coating method. • Highly conductive PEDOT:PSS films used as anode were prepared. • The ITO-free PSCs performance was comparable with that of the spin coated devices. • Our results suggest the possibility of replacing ITO with dip coated PEDOT:PSS

[en] Objective: To investigate the predictive value of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) enhanced MRI for microvascular invasion (MVI) in hepatocellular carcinoma (HCC). Methods: Retrospective analysis of 70 patients confirmed by pathology as HCC who underwent Gd-EOB-DTPA-enhanced MRI within 2 weeks prior to liver partial resection or liver transplantation surgery from January 2015 to May 2018 in Nantong Third People's Hospital. According to the pathological results of the postoperative pathology, MVI was divided into MVI positive group and MVI negative group, and alpha fetoprotein (AFP) was recorded. In Gd-EOB-DTPA-enhanced MRI, qualitative indicators including whether the tumor signal was uniform, peritumoral enhancement, tumor capsule, tumor margin, peritumor hypointensity and presence of fat in the tumor were assessed. Quantitative indicators including tumor diameter and the increase rate of liver-to-muscle ratio (ΔLMR) of post-enhancement arterial phase, portal vein phase, transitional phase and hepatobiliary phase were assessed and recorded. The x² test was used to compare the qualitative parameters of the MVI-negative group and the MVI-positive group, and the Mann-Whitney U test was used to compare the non-normal quantitative parameters. In both inclusion and non-inclusion of peritumor hypointensity cases in the hepatobiliary phase. The multivariate logistic regression analysis was performed to indicate independent variables after univariate analysis. The prediction probability 1 (pre-1) and the prediction probability 2 (pre-2) were obtained, and the two as independent variables. with MVI as the gold standard, using ROC to analyze the diagnostic efficacy of both for HCC MVI, and using Z test to compare the area under the ROC of pre-1 and pre-2. Results: There were 27 lesions in 26 cases of MVI-positive group and 50 lesions in 44 cases of MVI-negative group. There was a statistically significant difference between the MVI-negative group and the MVI-positive group in peritumoral enhancement, tumor capsule, tumor margin and peritumor hypointensity in the hepatobiliary phase (P < 0.05), and there was no statistically significant difference in gender distribution, tumor signal uniformity and intratumoral fat (P > 0.05). There was significant difference in lesion diameter between MVI-negative group and MVI-positive group (P < 0.05) while no significant difference in age, AFP value and ΔLMR between the two groups (P > 0.05). Multivariate logistic regression analysis showed that tumor diameter, non-smooth tumor margin and peritumor hypointensity were independent risks of MVI when peritumor hypointensity was included, the sensitivity and specificity of the combined diagnosis of MVI were 77.8% and 94.0%; Multivariate logistic regression analysis showed that tumor diameter and non-smooth tumor margin were independent risks of MVI when peritumor hypointensity was not included, the sensitivity and specificity of the combined diagnosis of MVI were 59.3% and 92.0%. The the area under the ROC of pre-1 and pre-2 were 0.900 and 0.816, their difference was statistically significant (P < 0.05). Conclusion: Gd-EOB-DTPA enhanced MRI can be used to predict HCC MVI preoperatively, especially peritumor hypointensity in hepatobiliary phase is important for the prediction of MVI. (authors)

[en] This paper summarizes the history and features of Advanced Small Water Reactor (ASWR), and provides recommendations and strategies on ASWR research and development in China. The ASWR can be used in remote power grid and replaces mid/small size fossil plant economically, and thus can be an important part of energy saving and emission reduction policy. The safety and economy characteristics of ASWR are able to effectively expand nuclear energy market in emerging countries and developing countries. Therefore, ASWR should be considered as a critical part of China's nuclear technology and equipment export strategy. (authors)

[en] High static power limits the application of conventional current-mode logic(CML). This paper presents a power-efficient switchable CML driver, which achieves a significant current saving by 75% compared with conventional ones. Implemented in the 130 nm CMOS technology process, the proposed CML driver just occupies an area about 0.003 mm"2 and provides a robust differential signal of 1600 mV for 10 Gbps optical line terminal (OLT) with a total current of 10 mA. The peak-to-peak jitter is about 4 ps (0.04T_U_I) and the offset voltage is 347.2 mV @ 1600 mV_P_P. (paper)

[en] Highlights: ► We report on an experimental study and photographic investigation of subcooled flow boiling. ► Data representing bubble growth, departure size, and distribution are presented. ► High nucleation density results in liquid supply shortage and initiates CHF. ► Visualization data did not show significant difference in hypervapotron structure. ► Hypervapotron delivers 40% higher CHF under identical conditions than flat surface. -- Abstract: This paper reports an experimental study and photographic investigation of the subcooled flow boiling on plain and augmented (hypervapotron) surfaces. The test sections are single-side heated and have a projected heating surface of 12.25 × 100 mm. Subcooled flow boiling heat transfer results were obtained from onset of nucleate boiling to critical heat flux and film boiling under conditions of inlet subcooling range from 10 °C to 30 °C, outlet pressure range from 0.4 to 0.8 MPa and mass flow rate range from 124 to 372 kg/m² s. The data of bubble growth, bubble departure size, nucleation distribution are measured. Nucleation distribution has an exponential relationship with uniform heat flux under moderate and high heat flux in subcooled flow boiling. The high nucleation density results in liquid supply shortage for nucleation and local dryout, which possibly initiates CHF. The visualization data did not show significant difference in hypervapotron structure with respect to bubble growth, departure and nucleation distribution, although hypervapotron delivers 40–50% higher CHF under same thermohydraulic conditions.

[en] This research examines bubble departure and bubble lift-off phenomena under subcooled nucleate boiling condition, using a high fidelity digital imaging apparatus. Refrigerant R- 134a is chosen as a simulant fluid due to its merits of having smaller surface tension, reduced latent heat, and lower boiling temperature than water. Images at frame rates up to 4000 frames/s were obtained with varying experimental parameters e.g. pressure, inlet sub-cooled level, and flow rate, etc., showing characteristics of bubble behavior under different conditions. Bubble size and position information was calculated via Canny's algorithm for edge detection and Fitzgibbon's algorithm for ellipse fitting. Bubble departure and lift-off radiuses were obtained and compared with existing bubble forces and detachment models proposed by Thorncroft et al., with good agreement observed. (authors)

[en] Due to their heat/cool storage characteristics, thermostatically controlled loads (TCLs) play an important role in demand response programmers. However, modeling of the heat/cool storage characteristic of large numbers of TCLs is not simple. In this paper, the heat exchange power is adopted to calculate the power instead of the average power, and the relationship between the heat exchange power and energy storage is considered to develop an equivalent storage model, based on which the time-varying power constraints and the energy storage constraints are developed, to establish the overall day-ahead scheduling model. Finally, the proposed scheduling method is verified using the simulation results of a six-bus system.

[en] In order to study the entrainment phenomenon of the fourth stage automatic depressurization system (ADS-4) under real conditions, the full scale test facility for liquid entrainment (FATE) was designed and constructed in accordance with CAP1400 with the ratio of 1:1. Boric acid solution was used as the working fluid to simulate the actual flow conditions in the reactor core. The entrainment process was recorded by a data acquisition device and a high-speed camera, and the acquired data were compared with those of the deionized water condition and the existing models. The results show that the experimental results of the boric acid and deionized water conditions are different from previous models for the entrainment onset and steady entrainment rate. The condition of boric acid is similar to that of deionized water, and the Froude number decreases with the increase of entrainment initial level. Entrainment onset is more likely to occur from top to down condition, and both have a hysteresis effect. There are also differences between the boric acid condition and the deionized water condition, which is mainly due to the different physical characteristics, especially the influence of density and viscosity. (authors)