[en] Highlights: • A performance metric is proposed with the consideration of price, environment effect, and service quality. • Models of a microgrid and a microgrid network are designed with distribute energy resources and storage. • Different cases in MG operation are discussed. - Abstract: A smart grid power system with renewable energy resources and distributed energy storage shows significant improvement in the power system’s emission reduction, reliability, efficiency, and security. A microgrid is a smart grid in a small scale which can be stand-alone or grid-tied. Multi microgrids form a network with energy management and operational planning through two-way power flow and communication. To comprehensively evaluate the performance of a microgrid, a performance metric is proposed with consideration of the electricity price, emission, and service quality, each of them is given a weighting factor. Thus, the performance metric is flexible according to the consumers’ preference. With the weighting factors set in this paper, this performance metric is further applied on microgrids operated as stand-alone, grid-tied, and networked. Each microgrid consists of a solar panel, a hydrogen fuel cell stack, an electrolyzer, a hydrogen storage tank, and a load. For a stand-alone system, the load prediction lowers down the daily electricity consumption about 5.7%, the quantity of H₂ stored fluctuates in a wide range, and overall performance indexes increase with the solar panel size. In a grid-tied MG, the load prediction has a significant effect on the daily consumed electricity which drops 25% in 4 days, some day-time loads are shifted to the night time, and the capacity of hydrogen tank is lower than that in a stand-alone MG. In a network with multiple MGs, the control of the power distribution strongly affects the MG’s performance. However, the overall performance index instead of any specific index increases with the MG’s power generated from renewable energy resources

[en] The first experiment of ring image Cherenkov detector (RICH) used aerogel in the world was reported in this paper. We built RICH using aerogel as illuminant for HERMES. The refractive index and size of all aerogel tiles were measured in order to select them for construction of RICH. The select conditions of tile were 113.1 < x,y < 115.1 mm, 10.25 < z < 12.25 mm and 1.0290 < n < 1.0313. Then, 1040 tiles were selected. They were selected again under the conditions 1.0290 < n < 1.0302 and 1.0303 < n < 1.0313 for each two RICH. These conditions were determined to match with σ < 3.0 · 10^-4, the dispersion of refractive index of aerogel tile, which condition was fitted to the accuracy of Cherenkov light emission angle of RICH. The mean thickness, transmission and reflection of tile, the thickness of corner of tile (thickness of surface), the refractive index dependence on position and temperature were measured. The effect of thickness of tile on the shift of Cherenkov emission angle was 6.1% the maximum value per one tile and 0.18% mean value of center. The effect of position dependence of refractive index on the Cherenkov light emission angle was agreed with the effect of dispersion of thickness of tile. The transmission and reflection of tile were almost same as the theoretical value. (S.Y.)

[en] Highlights: • Two microgrids with different structure are simulated. • Their performance are comprehensively evaluated and compared. • The one with DES and a FC stack has high environmental and quality indexes. - Abstract: In a heat-power system, the use of distributed energy generation and storage not only improves system’s efficiency and reliability but also reduce the emission. This paper is focused on the comprehensive performance evaluation of a grid-tied microgrid, which consists of a PV system, a hydrogen fuel cell stack, a PEM electrolyzer, and a hydrogen tank. Electricity and heat are generated in this system, to meet the local electric and heat demands. The surplus electricity can be stored as hydrogen, which is supplied to the fuel cell stack to generate heat and power as needed. The performance of the microgrid is comprehensively evaluated and is compared with another microgrid without a fuel cell stack. As a result, the emission and the service quality in the first system are higher than those in the second one. But they both have the same overall performance

[en] Highlights: • The B and BC type borehole geometry were systematically compared. • A heat transfer model was developed for the BC type borehole geometry. • The proposed model for BC type geometry was validated using the Sandbox experiment. • 15.63% of investment can be saved when the BC type borehole geometry is adopted. • A large relative thermal conductivity and U-pipe shank spacing are recommended. -- Abstract: The geometry of borehole heat exchangers (BHEs) is important for their sizing. In practice, a U-pipe can be located anywhere inside a borehole. To simplify the BHE modeling, ASHRAE has two standardized borehole geometries (the B type and BC type borehole geometry). In general, the B type is hard to achieve, although it is widely used in current BHE sizing. The BC type is the one that most likely occurs in practice, but there is a lack of detailed studies. This study presents a comparative analysis of the effects of U-pipe locations on BHE sizing. As current models are only feasible for the B type, a model for the BC type is first developed and verified using the well-known Sandbox experiment developed by Beier. Then, a comparative study of the B and BC types is conducted using the borehole depth and investment costs of a real office building. Finally, the factors influencing the borehole depth differences of the B or BC types are discussed, and guidelines for future BHE sizing are suggested.

[en] Compressive ghost imaging (CSGI) combines structured illumination and a bucket detector for obtaining the light intensity signal from an unknown object. Light fluctuations are generated by few measurements and then an image is reconstructed using optimization algorithms such as compressive sensing (CS) by finding its sparse representation. The measured light fluctuations are not sensitive to scattering degradation. Consequently, an absorbing object completely embedded in a scattering media can be imaged. To speed up the sequential loading of illumination patterns on a digital micromirror device and achieve data compression, the sampling number should be reduced because more than 90% of the time in CS reconstruction is usually spent in getting a frame of image. In this study, we propose a novel strategy to realize a speedy and reliable reconstruction procedure for obtaining a high image quality by using prior knowledge during the acquisition of light intensity signal in CSGI. The prior knowledge is established by extracting the features of a local target area, which is designed by descattering of images with extra noise using fast Fourier single-pixel imaging. The proposed method facilitates a reliable image quality even under the reduction in the compression ratio, thereby overcoming the limitation of the dependence of sampling ratio on the image quality in CSGI. (paper)

[en] Highlights: • A thermoelectric cooling (TEC) system coupled with a heat pipe is proposed. • A mathematical model of the heat transfer, based on the energy conservation, is established. • The cooling capacity is improved by 64.8% and the electricity consumption was reduced by 39.3%. - Abstract: Heat generated by electronic devices in small spaces is significant and continues to increase as more of these devices are brought into the work place as software and internet technologies are developed. Therefore, thermal management of electronic devices is crucial to avoid malfunction and failure of critical hardware as a result of overheating. To regulate heat buildup within electronic devices, a thermoelectric cooling (TEC) system coupled with a gravity-assisted heat pipe is proposed in this paper. A mathematical model of the heat transfer, based on energy conservation equations, was developed to analyze the system. A prototype system was designed, built, and tested as part of this work. The testing took place in a climatic chamber where various ambient conditions were simulated. The cooling capacity of the proposed system when several working fluid filling masses were used was monitored for different cooling demands. The results showed that the cooling capacity was improved by 64.8% and the electricity consumption was reduced by 39.3% for similar conditions when the proposed system was compared to a TEC system with an air cooling heat sink.

[en] Highlights: • Interaction of volatile organic compounds (VOCs) with pulmonary surfactant (PS) was probed. • VOCs obviously altered the surface tension and compression isotherm of PS. • PS displayed notable solubilization effect on VOCs. • Protein components of PS exhibited inhibitive effect on the solubilization of lipids. • Mixed phospholipids were responsible for the solubilization of PS for VOCs. -- Abstract: Exposure of volatile organic compounds (VOCs) towards lung leads to pulmonary dysfunctions and various lung diseases. However, the interaction of VOCs with pulmonary surfactant (PS) that directly comes into contact with inhaled VOCs is unknown. Here, simulated PS extracted from porcine lungs (EPS) was used to study the interaction with BTEX (i.e., benzene, toluene, ethylbenzene, and p-xylene) as representatives of VOCs. Surface pressure-area (π-A) isotherms showed that in the presence of individual BTEX, EPS monolayer’s phase conversion from gas to liquid expanded phase was dramatically influenced and its collapse pressure decreased greatly compared to those of EPS alone, which was attributed to the alteration of EPS monolayer’s microstructure characterized by atomic force microscopy and Brewster angle microscopy. Solubilization experiments manifested that EPS and its major components (dipalmitoyl phosphatidylcholine, DPPC; bovine serum albumin, BSA) exhibited obvious solubilization effects on individual BTEX. The solubilization capacity followed an order: EPS > DPPC > BSA, which was positively correlated with hydrophobicity of individual BTEX. Synergistic solubilization test unveiled that the mixed phospholipid components were largely responsible for the solubilization capacity of EPS. These findings indicate that VOCs exposure may induce potential pulmonary health risk due to the alteration of gas-liquid interfacial properties of PS.

[en] The α-decay energies(Q_α) are systematically investigated with the nuclear masses for 10 ≤ Z ≤ 120 isotopes obtained by the relativistic continuum Hartree-Bogoliubov (RCHB) theory with the covariant density functional PC-PK1, and compared with available experimental values. It is found that the α-decay energies deduced from the RCHB results present a similar pattern to those from available experiments. Owing to the large predicted Q_α values(4 MeV), many undiscovered heavy nuclei in the proton-rich side and super-heavy nuclei may have large possibilities for α-decay. The influence of nuclear shell structure on α-decay energies is also analysed. (authors)

[en] Highlights: • Pure Sn₄P₃ nanosheets are fabricated via a facile two-step method. • Progressive lithiation process of Sn₄P₃ is validated by calculations and CV. • Calculations verify that the formation of a-Li₃P is earlier than c-Li_4.4Sn. • Pure Sn₄P₃ exhibits a high specific capacity of 567 mAh g⁻¹ after 500 cycles. As the anodes for Li-ion batteries, the metal phosphides exhibit lower voltage range than those of sulfides and oxides, thus leading to a higher power/energy density for the full cells. Among the metal phosphides, Sn₄P₃ is a promising choice due to its relatively high specific capacity. However, the lithiation process of Sn₄P₃ has not been well understood by the existing literature. To verify this issue, experimental program and calculational analysis are conducted in this study. Firstly, the Sn₄P₃ nanosheets are produced with a facile two-step method of direct current arc plasma and phosphating. The test results confirm the excellent cycling stability of the prepared Sn₄P₃. Moreover, cyclic voltammetry analysis and first-principles calculations reveal that Sn₄P₃ experiences a progressive lithiation process, i.e., Li⁺ is firstly inserted into Sn₄P₃ to form the main intermediate products of amorphous Li_xSn₄P₃, followed by a conversion to the amorphous Li₃P (a-Li₃P) and the crystalline Li_4.4Sn (c-Li_4.4Sn). The formation of a-Li₃P is earlier than c-Li_4.4Sn, which is verified by the radial distribution functions of Sn and P, the numbers of Sn_n and P_n clusters, and the Bader populations of Sn and P in a-Li_xSn₄P₃.

[en] Combining first-principles accuracy and empirical-potential efficiency for the description of the potential energy surface (PES) is the philosopher’s stone for unraveling the nature of matter via atomistic simulation. This has been particularly challenging for multi-component alloy systems due to the complex and non-linear nature of the associated PES. In this work, we develop an accurate PES model for the Al–Cu–Mg system by employing deep potential (DP), a neural network based representation of the PES, and DP generator (DP-GEN), a concurrent-learning scheme that generates a compact set of ab initio data for training. The resulting DP model gives predictions consistent with first-principles calculations for various binary and ternary systems on their fundamental energetic and mechanical properties, including formation energy, equilibrium volume, equation of state, interstitial energy, vacancy and surface formation energy, as well as elastic moduli. Extensive benchmark shows that the DP model is ready and will be useful for atomistic modeling of the Al–Cu–Mg system within the full range of concentration. (special topic)