The Effect of Inlet Angle Structure of Concave and Convex Plate on Internal Flow Characteristics of Alkaline Electrolyzer

The structure of the concave-convex plates has proven to be crucial in optimizing the internal flow characteristics of the electrolyzer for hydrogen production.This paper investigates the impact of the gradual expansion angle of the inlet channel on the internal flow field of alkaline electrolyzers.The flow distribution characteristics of concave-convex plates with different inlet angle structures in the electrolytic cell is discussed.Besides,the system with internal heat source is studied.The results indicate that a moderate gradual expansion angle is beneficial for enhancing fluid uniformity.However,an excessively large gradual expansion angle may lead to adverse reflux phenomena,reducing the overall performance of the electrolytic cell.

An Angle Structure Descriptor for Image Retrieval

This paper presents an efficient image feature representation method, namely angle structure descriptor(ASD), which is built based on the angle structures of images. According to the diversity in directions, angle structures are defined in local blocks. Combining color information in HSV color space, we use angle structures to detect images. The internal correlations between neighboring pixels in angle structures are explored to form a feature vector. With angle structures as bridges, ASD extracts image features by integrating multiple information as a whole, such as color, texture, shape and spatial layout information. In addition, the proposed algorithm is efficient for image retrieval without any clustering implementation or model training. Experimental results demonstrate that ASD outperforms the other related algorithms.

Concurrent multi-scale design optimization of composite frame structures using the Heaviside penalization of discrete material model

This paper deals with the concurrent multi-scale optimization design of frame structure composed of glass or carbon fiber reinforced polymer laminates. In the composite frame structure, the fiber winding angle at the micro-material scale and the geometrical parameter of components of the frame in the macro-structural scale are introduced as the independent variables on the two geometrical scales. Considering manufacturing requirements, discrete fiber winding angles are specified for the micro design variable. The improved Heaviside penalization discrete material optimization interpolation scheme has been applied to achieve the discrete optimization design of the fiber winding angle. An optimization model based on the minimum structural compliance and the specified fiber material volume constraint has been established. The sensitivity information about the two geometrical scales design variables are also deduced considering the characteristics of discrete fiber winding angles. The optimization results of the fiber winding angle or the macro structural topology on the two single geometrical scales, together with the concurrent two-scale optimization, is separately studied and compared in the paper. Numerical examples in the paper show that the concurrent multi-scale optimization can further explore the coupling effect between the macro-structure and micro-material of the composite to achieve an ultralight design of the composite frame structure. The novel two geometrical scales optimization model provides a new opportunity for the design of composite structure in aerospace and other industries.

Crystal Structure of 3-(4-Methoxyphenyl)-2-(4-methylbenzoyl)-6,7-dihydro-5H-furo[3,2-g]chromene

The crystal structure of 3-（4-methoxyphenyl）-2-（4-methylbenzoyl）-6,7-dihydro-5H-furo[3,2-g]chromene was obtained by X-ray single-crystal diffraction. The molecule is in the triclinic crystal system, space group P1 with a = 11.0745（4）, b = 13.0953（7）, c = 15.8773（8） ？, α = 92.811（4）, β = 104.815（4）, γ = 111.797（4）o, Z = 4, the final R = 0.0567 and w R = 0.1540. X-ray crystal structure data revealed that one asymmetric structure unit of the title compound contained two molecules. The existence of methyl group changed the dihedral angle between furan ring and the phenyl ring at the C2 position of the furo[3,2-g]chromene scaffold as well as the conformation, and had a further influence on the bioactivity of the furo[3,2-g]chromene derivatives.

The 20 April 2013 Lushan, Sichuan, mainshock, and its aftershock sequence: tectonic implications

Using the double-difference relocation algo- rithm, we relocated the 20 April 2013 Lushan, Sichuan, earthquake （Ms 7.0）, and its 4,567 aftershocks recorded during the period between 20 April and May 3, 2013. Our results showed that most aftershocks are relocated between 10 and 20 km depths, but some large aftershocks were relocated around 30 krn depth and small events extended upward near the surface. Vertical cross sections illustrate a shovel-shaped fault plane with a variable dip angle from the southwest to northeast along the fault. Furthermore, the dip angle of the fault plane is smaller around the mainshock than that in the surrounding areas along the fault. These results suggest that it may be easy to generate the strong earthquake in the place having a small dip angle of the fault, which is somewhat similar to the genesis of the 2008 Wenchuan earthquake. The Lushan mainshock is underlain by the seismically anomalous layers with low-Vp, low-Vs, and high-Poisson＇s ratio anomalies, possibly suggesting that the fluid-filled fractured rock matrices might signifi- cantly reduce the effective normal stress on the fault plane to bring the brittle failure. The seismic gap between Lushan and Wenchuan aftershocks is suspected to be vulnerable to future seismic risks at greater depths, if any.

Wide angle space laser communication receiver based on asymmetric array structure

In this paper, an asymmetric array structure of space laser communication receiver is proposed. This structure can greatly reduce alignment requirement, and lighten the signal strength jitter caused by atmospheric turbulence. A prototype of the proposed structure is fabricated and a 2.5 Mbit/s on-off keying(OOK) modulated demonstration link over 40 m free space is built. This asymmetric array structure can effectively collect optical signal while rotating in a window angle of ±17°, and the bit error ratio(BER) keeps zero.

Characteristics of reattached boundary layer in shock wave and turbulent boundary layer interaction

The reattached boundary layer in the interaction of an oblique shock wave with a flatplate turbulent boundary layer at Mach number 2.25 is studied by means of Direct Numerical Simulation(DNS).The numerical results are carefully compared with available experimental and DNS data in terms of turbulence statistics,wall pressure and skin friction.The coherent vortex structures are significantly enhanced due to the shock interaction,and the reattached boundary layer is characterized by large-scale structures in the outer region.The space-time correlation of fluctuating wall shear stress and streamwise velocity fluctuation reveals that the structural inclination angle exhibits a gradual decrease during the recovery process.The scale interactions are analyzed by using a twopoint amplitude modulation correlation.A possible mechanism is proposed to account for the strong amplitude modulation in the downstream region.Moreover,the mean skin-friction is decomposed to understand the physically informed contributions.Unlike the upstream Turbulent Boundary Layer(TBL),the contribution associated with the Turbulence Kinetic Energy(TKE)production is greatly amplified,while the spatial growth contribution induced by the pressure gradient largely inhibits skin-friction generation.Based on bidimensional empirical mode decomposition,the turbulence kinetic energy production contribution is further split into different terms with specific spanwise length scales.