ALBERT

Description: Despite many studies reporting hemispheric asymmetry in the representation and processing of emotions, the essence of the asymmetry remains controversial. Brain network analysis based on electroencephalography (EEG) is a useful biological method to study brain function. Here, EEG data were recorded while participants watched different emotional videos. According to the videos’ emotional categories, the data were divided into four categories: high arousal high valence (HAHV), low arousal high valence (LAHV), low arousal low valence (LALV) and high arousal low valence (HALV). The phase lag index as a connectivity index was calculated in theta (4–7 Hz), alpha (8–13 Hz), beta (14–30 Hz) and gamma (31–45 Hz) bands. Hemispheric networks were constructed for each trial, and graph theory was applied to quantify the hemispheric networks’ topological properties. Statistical analyses showed significant topological differences in the gamma band. The left hemispheric network showed significantly higher clustering coefficient (Cp), global efficiency (Eg) and local efficiency (Eloc) and lower characteristic path length (Lp) under HAHV emotion. The right hemispheric network showed significantly higher Cp and Eloc and lower Lp under HALV emotion. The results showed that the left hemisphere was dominant for HAHV emotion, while the right hemisphere was dominant for HALV emotion. The research revealed the relationship between emotion and hemispheric asymmetry from the perspective of brain networks.

Description: The demand for heat-resistant steel has increased owing to its utility in numerous devices that must withstand high steam pressures and high temperatures, such as turbine rotors and blades in ultra-supercritical power plants. It is inevitable to join heat-resistance steel part by welding method, so it is important to maintain the toughness of the weld metals. In this study, the microstructure, low-temperature impact toughness, and fracture surface of as-welded and post-weld heat treatment (PWHT) of 2.25Cr-1Mo-0.25V weld metal were investigated. The microstructures of the as-welded and PWHT specimens are granular bainite and ferrite, respectively. This work revealed the relationship between effective microstructure nearby crack initiation origin and low temperature impact toughness for both the as-welded and PWHT specimens. The evolution of the microstructure and prior austenite was then investigated using confocal laser scanning microscopy (CLSM) to observe the formation of coarse ferrite grain structures. A suggestion for enhancing the low-temperature toughness was provided based on the effect of adjusting Mn content and forming acicular ferrite.

Description: Non-destructive tests working at lower microwave frequencies have large advantages of dielectric material penetrability, lower equipment cost, and lower implementation complexity. However, the resolution will become worse as the work frequencies become lower. Relying on designing the structure of high field confinement, this study realizes a simple complementary spiral resonators (CSRs)-based near-field probe for microwave non-destructive testing (NDT) and imaging around 390 MHz (λ = 769 mm) whereby very high resolution (λ/308, 2.5 mm) is achieved. By applying an ingenious structure where a short microstrip is connected to a microstrip ring to feed the CSR, the probe, that is a single-port microwave planar circuit, does not need any extra matching circuits, which has more application potential in sensor arraying compared with other microwave probes. The variation of the electric field distribution with the standoff distance (SOD) between the material under test and the probe are analyzed to reveal the operation mechanisms behind the improved sensitivity and resolution of the proposed probe. Besides, the detection abilities of the tiny defects in metal and non-metal materials are demonstrated by the related experiments. The smallest detectable crack and via in the non-metal materials and the metal materials are of a λ/1538 (0.5 mm) width, a λ/513 (1.5 mm) diameter, a λ/3846 (0.2 mm) width and a λ/513 (1.5 mm) diameter, respectively. Moreover, to further evaluate the performance of the proposed probe, the defects under skin layer in the multilayer composite materials and the defects under corrosion in the carbon steel are inspected and imaged. Due to lower work frequency, high resolution, outstanding detection abilities of tiny defects, and large potentials in sensor arraying, the proposed probe would be a good candidate for microwave NDT and imaging.

Description: Density functional theory calculations of the layer (L)-dependent electronic band structure, work function and optical properties of β-InSe have been reported. Owing to the quantum size effects (QSEs) in β-InSe, the band structures exhibit direct-to-indirect transitions from bulk β-InSe to few-layer β-InSe. The work functions decrease monotonically from 5.22 eV (1 L) to 5.0 eV (6 L) and then remain constant at 4.99 eV for 7 L and 8 L and drop down to 4.77 eV (bulk β-InSe). For optical properties, the imaginary part of the dielectric function has a strong dependence on the thickness variation. Layer control in two-dimensional layered materials provides an effective strategy to modulate the layer-dependent properties which have potential applications in the next-generation high performance electronic and optoelectronic devices.

Description: Fritillariae Bulbus is a precious Chinese herbal medicine that is grown at high elevation and used to relieve coughs, remove phlegm, and nourish the lungs. Historically, Fritillariae Bulbus has been divided into two odourless crude drugs: Fritillariae Cirrhosae Bulbus and Fritillariae Thunbergii Bulbus. However, now the Chinese Pharmacopoeia has described five Fritillariae Bulbus—the new additions include Fritillariae Pallidiflorae Bulbus, Fritillariae Ussuriensis Bulbus, and Fritillariae Hupehensis Bulbus. Because the morphology of dried Fritillariae Bulbus is similar, it is difficult to accurately identify the different types of Fritillariae Bulbus. In the current study, we develop a method combining DNA barcoding and high-performance liquid chromatography (HPLC) to help distinguish Fritillariae Cirrhosae Bulbus from other Fritillariae Bulbus and guarantee species traceability of the five types of Fritillariae Bulbus. We report on the validation of an integrated analysis method for plant species identification using DNA barcoding that is based on genetic distance, identification efficiency, inter- and intra-specific variation, calculated nearest distance, neighbour-joining tree and barcoding gap. Our results show that the DNA barcoding data successfully identified the five Fritillariae Bulbus by internal transcribed spacer region (ITS) and ITS2, with the ability to distinguish the species origin of these Fritillariae Bulbus. ITS2 can serve as a potentially useful DNA barcode for the Fritillaria species. Additionally, the effective chemical constituents are identified by HPLC combined with a chemical identification method to classify Fritillaria. The HPLC fingerprint data and HCA (hierarchical clustering analysis) show that Fritillariae Cirrhosae Bulbus is clearly different from Fritillariae Thunbergii Bulbus and Fritillariae Hupehensis Bulbus, but there is no difference between Fritillariae Cirrhosae Bulbus, Fritillariae Ussuriensis Bulbus, and Fritillariae Pallidiflorae Bulbus. These results show that DNA barcoding and HPLC fingerprinting can discriminate between the five Fritillariae Bulbus types and trace species to identify related species that are genetically similar.

Description: The increasing peak-to-valley load difference in China pose a challenge to long-distance and large-capacity hydropower transmission via high-voltage direct current (HVDC) lines. Considering the peak shaving demands of load centers, an optimization model that maximizes the expected power generation revenue is proposed here for the long-term operation of an interprovincial hydropower plant. A simulation-based method was utilized to explore the relationships between long-term power generation and short-term peak shaving revenue in the model. This method generated representative daily load scenarios via cluster analysis and approximated the real-time electricity price of each load profile with the time-of-use price strategy. A mixed-integer linear programming model with HVDC transmission constraints was then established to obtain moving average (MA) price curves that bridged two time-coupled operations. The MA price curves were finally incorporated into the long-term optimization model to determine monthly generation schedules, and the inflow uncertainty was addressed by discretized inflow scenarios. The proposed model was evaluated based on the operation of the Xiluodu hydropower system in China during the drawdown season. The results revealed a trade-off between long-term energy production and short-term peak shaving revenue, and they demonstrated the revenue potential of interprovincial hydropower transmission while meeting peak shaving demands. A comparison with other long-term optimization methods demonstrated the effectiveness and reliability of the proposed model in maximizing power generation revenue.

Description: Selective laser surface melting, which brings together the bionic theory and the laser process, is an effective way to enhance the thermal fatigue behavior of materials. In this study, in order to examine the relationship between the mechanical properties and thermal fatigue behavior of materials processed by selective laser surface melting, the tensile properties at room temperature and elevated temperature of treated specimens and untreated specimens after different numbers of thermal fatigue cycles were investigated and compared. Moreover, the microstructure evolution and the microhardness of the laser-affected zone were investigated after different numbers of thermal fatigue cycles. The results show that microhardness of the laser-melted zone gradually decreases with an increasing number of thermal fatigue cycles; the number of thermal fatigue cycles has little effect on the grain size in the laser-melted zone, and the percentage of low-angle grain boundaries decreases with an increasing number of thermal fatigue cycles. The strength of specimens gradually decreases, whereas the fracture elongation gradually increases with an increasing number of thermal fatigue cycles at room temperature and elevated temperature. In addition, the stress distribution on the specimen surface during tensile test was investigated using the finite element method, and the results indicate that the stress transfer exists between the laser-affected zone and the untreated zone.

Description: Miniature drainage pumps with a radial blade are widely used in situations with critical constant head and low noise requests, but the stable operation state is often broken up by the entraining gas. In order to explore the internal flow characteristics under gas–liquid two phase flow, pump performance and emitted noise measurements were processed under different working conditions. Three-dimensional numerical calculations based on the Euler inhomogeneous model and obtained experimental boundaries were carried out under different inlet air void fractions (IAVFs). A hybrid numerical method was proposed to obtain the flow-induced emitted noise characteristics. The results show there is little influence on pump characteristics when the IAVF is less than 1%. The pump head slope degradation was found to increase with air content. The bubbles adhere to the impeller hub on the blade’s suction side and spread to the periphery with a big IAVF, leading to unstable operation. It is obvious that vortices appear inside the impeller flow passage as IAVF reaches 6.5%. The two-phase flow pattern has a small effect on the characteristic frequency distribution of pressure fluctuation and emitted noise, but the corresponding pulsation intensity and noise level will increase. The study could provide some reference for low noise design of the drainage pump.

Description: Cold metal transfer process is applied to join titanium and Q235 steel with copper filler metal. Scanning electron microscope (SEM), energy dispersive spectrometer (EDS) analysis, micro-hardness tests, and tensile strength test were performed to investigate the joining mechanism and strength of joints. The results show that the stacking order of two base metals affected the joining modes and strength. For top Q235 steel to bottom Ti-TA2 lapped joint, there was no distinct interface reaction layer between the steel base metal and the weld metal; dispersed TiFe2 intermetalics (IMCs) IMCs between the steel base metal and the Ti base metal greatly improved the strength of joint; the tensile force of the joint could reach up to 93% that of steel-steel joint using the same welding parameters. Additionally, the joints were fractured in dimple mode at the steel base metal. For top Ti-TA2 to bottom Q235 steel lapped joint, the increasing volume fraction of Ti-Cu IMCs at the Ti-Cu weld metal interface contributed to the strength of joint degradation. The joints under tensile loading are initiated at the Ti-Cu weld metal interface between the weld metal and Ti base metal, then propagated to weld metal, finally fractured with brittle mode.