Low Li ion diffusion barrier on low-crystalline FeOOH nanosheets and high performance of energy storage

Nano Research - To obtain symmetric supercapacitors (SCs) with high energy density, it is critical to fabricate an electrode with wide potential window and excellent capacitive performance. Herein,...     

Epigenetic Regulation of the Hippocampus,with Special Reference to Radiation Exposure

The hippocampus is crucial in learning, memory and emotion processing, and is involved in the development of different neurological and neuropsychological disorders. Several epigenetic factors, including DNA methylation, histone modifications and non-coding RNAs, have been shown to regulate the development and function of the hippocampus, and the alteration of epigenetic regulation may play important roles in the development of neurocognitive and neurodegenerative diseases. This review summarizes the epigenetic modifications of various cell types and processes within the hippocampus and their resulting effects on cognition, memory and overall hippocampal function. In addition, the effects of exposure to radiation that may induce a myriad of epigenetic changes in the hippocampus are reviewed. By assessing and evaluating the current literature, we hope to prompt a more thorough understanding of the molecular mechanisms that underlie radiation-induced epigenetic changes, an area which can be further explored.     

B对FeCoCrNiSiBx高熵合金激光熔覆层组织和硬度的影响

采用激光熔覆制备了FeCoCrNiSiB_x高熵合金熔覆层,利用光学显微镜、扫描电镜、X射线衍射仪和显微硬度计研究微量硼元素(摩尔比x=0、0.02、0.04、0.06、0.08)对FeCoCrNiSiB_x高熵合金熔覆层组织和硬度的影响。结果表明:无B高熵合金涂层组织主要为胞状晶。B的添加会促进枝晶的生成,逐渐形成鱼骨状树枝晶,但过量的B会破坏枝晶完整性,形成蠕虫状晶。此外,高熵合金熔覆层组织为FCC和BCC双相结构,B元素的添加会形成大量0.1~2.6 μm的Cr₂B第二相,有助于提高熔覆层硬度,其中x=0.06时激光熔覆层的硬度最高,约为537 HV0.2。     

Electron beam processed surface textures on titanium alloys for fluid-drag reduction

Ti-6Al-4V and Ti-4Al-1.5Mn alloys were employed for electron beam processing with the aim to produce surface textures efficient for fluid-drag reduction. The as-resulted surface textures were examined by using advanced optical microscopy for surface morphology analysis, optical microscopy and scanning electron microscopy for near-surface microstructure observation. The titanium model with electron beam processed surface textures was tested in wind tunnel to evaluate their fluid-drag reduction efficiency. It showed that the as-resulted non-smooth surface was characterized by parallel ridges and grooves, with height and spacing able to be customized by adjusting processing parametres. The ridges displayed continuous scales while the valley of grooves presented V-shaped ripples. Their dimensions were also related to and could be controlled by processing parametres. Further, the near-surface region was occupied by fusion zone, heat-affected zone and base metal from the outermost surface to the underlying bulk alloy. The microstructure of fusion zone was characterized by martensite phase. A heat-affected zone was sandwiched between fusion zone and the underlying base metal, with different microstructural features compared to both fusion zone and the base metal. With respect to fluid-drag reduction efficiency, titanium model with electron beam processed surface textures exhibits a reducing efficiency over 15% at attack angles of 0° and ±1°, with an air flow velocity at 24 m/s.     

Research on heat dissipation performance and flow characteristics of air‐cooled battery pack

With the depletion of fossil fuels and the aggravation of environmental pollution, the research and development speed of electric vehicles has been accelerating, and the thermal management of battery pack has become increasingly important. This paper selects the electric vehicle battery pack with natural air cooling as the study subject, conducts simulation analysis of the heat dissipation performance of battery packs with and without vents. Then this paper researches on the influence of internal flow field and external flow field. Field synergy principle is used to analyze the effect of velocity field and temperature field amplitude. The results show the following: it is found that the maximum temperature rise and the internal maximum temperature difference of the battery pack with vents are reduced by about 23.1% and 19.9%, raising speed value can improve the heat dissipation performance, and raising temperature value can decrease the heat dissipation performance. Reasonable design of the vents can make the inner and outer flow field work synergistically to achieve the best cooling effect. Then the reference basis for the air cooling heat dissipation performance analysis of electric vehicle, battery pack structure arrangement, and air‐inlet and air‐outlet pattern choosing are offered.     

EGGS: Sparsity-Specific Code Generation

Sparse matrix computations are among the most important computational patterns, commonly used in geometry processing, physical simulation, graph algorithms, and other situations where sparse data arises. In many cases, the structure of a sparse matrix is known a priori, but the values may change or depend on inputs to the algorithm. We propose a new methodology for compile-time specialization of algorithms relying on mixing sparse and dense linear algebra operations, using an extension to the widely-used open source Eigen package. In contrast to library approaches optimizing individual building blocks of a computation (such as sparse matrix product), we generate reusable sparsity-specific implementations for a given algorithm, utilizing vector intrinsics and reducing unnecessary scanning through matrix structures. We demonstrate the effectiveness of our technique on a benchmark of artificial expressions to quantitatively evaluate the benefit of our approach over the state-of-the-art library Intel MKL. To further demonstrate the practical applicability of our technique we show that our technique can improve performance, with minimal code changes, for mesh smoothing, mesh parametrization, volumetric deformation, optical flow, and computation of the Laplace operator.     

Effect of nonsolvent additives on PES ultrafiltration membrane pore structure

Different nonsolvent additives, namely, diethylene glycol, n-butyl alcohol (NBA), and ethylene glycol monomethyl ether, were added into the casting solution (polyethersulfone/dimethylformamide/lithium chloride) to prepare ultrafiltration (UF) membrane via phase inversion. The effects of different additives and their concentration on the pore structure of the prepared UF membrane were studied. The cross-sectional morphology of the membrane was observed via scanning electron microscopy. The addition of nonsolvent additives improved the large-cavity structure of the membrane. When the additive was low-content NBA (1–3 wt %), the membrane pore structure transformed from large-cavity structure to fully sponge-like structure. When the content of additive NBA was 3 wt %, the flux of the prepared UF membrane was 130.45 L (m⁻² h⁻¹), the rejection of PEG20000 was 95.54% and the flux remained high at 4 bar in long-term stability test. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47525.     

Manpower supply planning for aircraft line maintenance under stochastic incidents

We plan the manpower supply for aircraft line maintenance, taking into account two types of stochastic incidents: manpower demands for a flight and the number of aircraft needing to be serviced at one time. The problem is solved to find the shift and maintenance group combinations best suited for the given airline. The optimal aircraft maintenance certification for a crew is also analyzed to improve the entire manpower structure. In addition, the addition of temporary manpower required for actual daily operations is also considered as a part of understanding the total manpower utilized in actual operations. An integrated method including scenario generation and a stochastic model is developed to deal with the problem. Finally, we perform a case study based on operating data obtained from a major airline in Taiwan. The results and findings are compared with the airline’s current manpower plan in the discussion, and suggestions for improvement are made.     

Field‐based robotic phenotyping of sorghum plant architecture using stereo vision

Sorghum (Sorghum bicolor) is known as a major feedstock for biofuel production. To improve its biomass yield through genetic research, manually measuring yield component traits (e.g. plant height, stem diameter, leaf angle, leaf area, leaf number, and panicle size) in the field is the current best practice. However, such laborious and time‐consuming tasks have become a bottleneck limiting experiment scale and data acquisition frequency. This paper presents a high‐throughput field‐based robotic phenotyping system which performed side‐view stereo imaging for dense sorghum plants with a wide range of plant heights throughout the growing season. Our study demonstrated the suitability of stereo vision for field‐based three‐dimensional plant phenotyping when recent advances in stereo matching algorithms were incorporated. A robust data processing pipeline was developed to quantify the variations or morphological traits in plant architecture, which included plot‐based plant height, plot‐based plant width, convex hull volume, plant surface area, and stem diameter (semiautomated). These image‐derived measurements were highly repeatable and showed high correlations with the in‐field manual measurements. Meanwhile, manually collecting the same traits required a large amount of manpower and time compared to the robotic system. The results demonstrated that the proposed system could be a promising tool for large‐scale field‐based high‐throughput plant phenotyping of bioenergy crops.