Analysis of Optical Losses in a Photoelectrochemical Cell: A Tool for Precise Absorptance Estimation

Optical losses in a photoelectrochemical (PEC) cell account for a substantial part of solar‐to‐hydrogen conversion losses, but limited attention is paid to the detailed investigation of optical losses in PEC cells. In this work, an optical model of combined coherent and incoherent light propagation in all layers of the PEC cell based on spectroscopic measurements is presented. Specifically, photoelectrodes using transparent conductive substrates such as F:SnO₂ coated with thin absorber films are focused. The optical model is verified for hematite photoanodes fabricated by atomic layer deposition and successfully used to determine wavelength‐dependent reflection, transmission, layer absorptances, and charge generation rates. Furthermore, the calculated absorptances enable 20–30% more accurate calculations of the absorbed photon‐to‐current efficiency of PEC cells. Our optical model is a powerful tool for the optimization of the optical performance of PEC cells focusing on single absorber or tandem configurations and represents a cornerstone of a complete (optical and electrical) model for PEC water splitting cells.     

基于随钻电阻率成像测井的数据压缩方法

随钻测井作业与钻井作业同步进行,在钻井液滤液还未侵入地层或者侵入井壁很浅时获得测井资料,能准确反映原状地层特征,油气储量评价准确。图像压缩是随钻电阻率测井实时成像的关键技术,通过分析多种图像压缩方法,发现小波编码适合随钻电阻率成像测井,在此基础上,分析嵌入式零树编码和多级树集合分裂编码2种小波变换算法,进行Matlab仿真。多级树集合分裂编码方法在50倍压缩率条件下,能够保持较高的图像质量,可满足随钻电阻率测井实时成像数据压缩需要。     

Segmentation of neuronal nuclei based on clump splitting and a two-step binarization of images

In this paper we present an algorithm to segment the nuclei of neuronal cells in confocal microscopy images, a key technical problem in many experimental studies in the field of neuroscience. We describe the whole procedure, from the original images to the segmented individual nuclei, paying particular attention to the binarization of the images, which is not straightforward due to the technical difficulties related to the visualization of nuclei as individual objects and incomplete and irregular staining. We have focused on the division of clusters of nuclei that appear frequently in these images. Thus we have developed a clump-splitting algorithm to separate touching or overlapping nuclei allowing us to accurate account for both the number and size of the nuclei. The results presented in the paper show that the proposed algorithm performs well on different sets of images from different layers of the cerebral cortex.     

环氧树脂修复混凝土裂缝的断裂试验研究

对6个混凝土试件进行楔入劈拉试验,劈裂后采用环氧树脂注胶技术修复试件,然后再次对试件进行楔入劈拉试验,对比两次试验中试件的破坏界面和断裂参数.结果表明：修复后试件破坏界面未发生在黏结界面;试件起裂韧度平均增幅为4706%,失稳断裂韧度、断裂能也有所提高,这说明注胶修复技术能够有效推迟裂缝的再开展,改善混凝土的断裂性能.建议将起裂韧度作为评定注胶修复效果的断裂参数,研究成果可为注胶修复混凝土结构的工程应用提供依据.     

A RBF based finite difference method for option pricing under regime-switching jump-diffusion model

Abstract

In this article, we presented a method for option pricing problem under regime-switching jump-diffusion models. We have proposed a numerical method for solving a partial integro-differential equation (PIDE) for pricing European option and for solving linear complementarity problem (LCP), to evaluate the price of American options. We use implicit explicit method for time semi discretization, followed by radial basis function based finite difference (RBF-FD) method for spatial discretization to solve PIDE. The proposed method is further extended to solve the LCP by coupling it with operator splitting method. Numerical simulation is done for European and American option to demonstrate efficiency and accuracy of the proposed method.     

Surface engineered active photocatalysts without noble metals: CuS–ZnxCd1−xS nanospheres by one-step synthesis

CuS(y)–Zn_xCd_1−xS (where 0.3 ≤ x ≤ 0.8, 0% ≤ y ≤ 15.8%) nanospheres with a Zn and Cu-rich surface were synthesized via a one-step method in ethylene glycol. Structural, morphological and optical properties of the samples have been investigated by XRD, TEM, XPS, ICP, N₂ physisorption and UV–vis DRS techniques. The cubic phased nanospheres of approximately 20–30 nm in diameter are comprised of nanocrystals of about 5 nm. Due to the reactivity difference among the metal ions in the organic solvent, the surface of the nanospheres was found enriched with Zn and Cu sulfide layers. In the absence of Cu, sample Zn_0.65Cd_0.35S gives a H₂ production rate of 29 μmol/h under the irradiation of a 300 W Xenon lamp with a cut-off filter (λ ≥ 420 nm) in aqueous solutions containing S²⁻ and SO₃²⁻. The activity, which can only be increased by four times by a traditional Pt cocatalyst for the as-prepared Zn_0.65Cd_0.35S sample, can be enhanced by around 20 times to 550 μmol/h and 624 μmol/h after adding 5.9 mol% and 11.1 mol% (metal basis) of Cu during the synthesis to form a Cu-rich surface. It is believed that the surface Cu²⁺ 3d impurity levels can function as the same role of the noble metal cocatalysts as charge accommodation sites for the charge separation, and hence increase the photocatalytic performance for water splitting.     

基于层叠遗传算法的配电网多层级无源光网络优化

对于配用电光通信网中无源光网络多层级、多节点网络规划问题,首次提出采用基本遗传算法实现多层级的循环继承的层叠遗传算法。其采用外层分光网络继承内层网络基因用于本层网络的适应度函数选择,该算法解决了多层级无源光(PON)网络各层级分光优化的问题,并且通过仿真证明了其可行性,实现了四层级网络星形结构拓扑优化。优化后的网络获得了最优的星形网络拓扑和通信建设成本的降低。     

Improvement Properties of Cohesion-Less Soil Using Recycled Bassanite

Solid waste management is a serious problem over the world. Therefore, reduction, re-use and recycling of waste have become major issues in recent days. Gypsum waste plasterboard is considered one example of these waste materials. This study evaluates the use of recycled bassanite, which is derived from gypsum waste plasterboard, to enhance the performance of two types of cohesion-less soil. Recycled bassanite was utilized as a stabilizing agent to improve both compressive and splitting strengths of the tested soil. The effect of bassanite content, soil type, water content and curing time were investigated to explore the behavior of treated soil with recycled bassanite. Test results showed that increase of bassanite content is associated with increase in optimal moisture content, while no significant increase in the dry unit weight was observed. Both compressive and splitting tensile strengths enhanced with the additives of recycled bassanite. The increase of bassanite content had a more significant effect on the compressive strength compared with the effect on tensile strength. The use of recycled bassanite to enhance the strength of sandy soil had a more significant effect compared with silty soil. The effect of curing time on the strength of treated samples was more significant in early curing ages compared with late curing ages. The strength decreased significantly in case of stabilized samples prepared with water content at the wet-side of the compaction curve. However, insignificant decrease in the strength of the stabilized sample was detected with moisture content at the dry-side of compaction curve. This research meets the challenges of our society to reduce the quantities of gypsum wastes, producing useful material from waste materials that will help to a sustainable society.