Calculation of Nearly Singular Boundary Element Integrals in Thin Structures Using an Improved Exponential Transformation

In this work, an improved exponential transformation is presented for nearly singular boundary element integrals in problems of thin structures. Accurate evaluation of nearly singular integrals is an important issue in the implementation of boundary element method (BEM) for thin structures. In this paper, the exponential transformation, which was firstly developed to evaluate nearly singular integrals arising in 2D BEM, is extended into 3D BEM to deal with nearly singular integrals. Firstly, a novel (α,β) coordinate system is introduced. Then, the conventional distance function is modified into a new form in (α,β) coordinate system. Based on the refined distance function, finally, an improved exponential transformation is employed in the new coordinate system. Furthermore, to perform integrations on irregular elements, an adaptive integration scheme considering both the shape of element and the projection point associated with the improved transformation is proposed. Numerical examples are presented to verify the proposed method. Results demonstrate the accuracy and efficiency of our method. Moreover, the accuracy of our method is less sensitive to the position of the projection point than that of the traditional methods

POSS-based meso-/macroporous covalent networks: supporting and stabilizing Pd for Suzuki–Miyaura reaction at room temperature

Porous covalent organic networks synthesized by Schiff base chemistry reaction of POSS and terephthalic aldehyde could serve as both supports and stabilizers for Pd catalyst, which exhibited excellent performances for Suzuki-Miyaura reactions.</p

A spherical element subdivision method for the numerical evaluation of nearly singular integrals in 3D BEM

Purpose The purpose of this paper is to preset a spherical element subdivision method for the numerical evaluation of nearly singular integrals in three-dimensional (3D) boundary element method (BEM). Design/methodology/approach In this method, the source point is first projected to the tangent plane of the element. Then two cases are considered: the projection point is either inside or outside the element. In both cases, the element is subdivided into a number of patches using a sequence of spheres with decreasing radius. Findings With the proposed method, the patches obtained are automatically refined as they approach the projection point and each patch of the integration element is “good” in shape and size for standard Gaussian quadrature. Therefore, all kinds of nearly singular boundary integrals on elements of any shape and size with arbitrary source point location related to the element can be evaluated accurately and efficiently. Originality/value Numerical examples for planar and slender elements with various relative location of the source point are presented. The results demonstrate that our method has much better accuracy, efficiency and stability than conventional methods. </jats:sec

Zn-Doped SnO2 Compact Layer for Enhancing Performance of Perovskite Solar Cells

Perovskite solar cells (PSCs) have been developing rapidly since they were discovered, and their excellent photoelectric properties have attracted wide attention from researchers. The compact layer is an important part of PSCs, which can transport electrons and block holes. SnO2 is an excellent and commonly used electron transport layer (ETL) material, and doping modification is an effective way to improve performance. Here, Zn with a similar radius to Sn has been introduced to the doping of the SnO2 compact layer to achieve the purposes of conductivity enhancement of the compact layer and followed photoelectric performance improvement of the device. Zn-SnO2 compact layers with different doping concentrations were prepared and applied to mesoporous architecture PSCs. When the doping content was 5%, the power conversion efficiency (PCE) of the device based on the Zn-SnO2 compact layer has increased from 9.08% to 10.21%, with an increase of 12.44%. The doping of SnO2 promotes its application in low-cost PSCs

Zn-Doped SnO2 Compact Layer for Enhancing Performance of Perovskite Solar Cells

Perovskite solar cells (PSCs) have been developing rapidly since they were discovered, and their excellent photoelectric properties have attracted wide attention from researchers. The compact layer is an important part of PSCs, which can transport electrons and block holes. SnO2 is an excellent and commonly used electron transport layer (ETL) material, and doping modification is an effective way to improve performance. Here, Zn with a similar radius to Sn has been introduced to the doping of the SnO2 compact layer to achieve the purposes of conductivity enhancement of the compact layer and followed photoelectric performance improvement of the device. Zn-SnO2 compact layers with different doping concentrations were prepared and applied to mesoporous architecture PSCs. When the doping content was 5%, the power conversion efficiency (PCE) of the device based on the Zn-SnO2 compact layer has increased from 9.08% to 10.21%, with an increase of 12.44%. The doping of SnO2 promotes its application in low-cost PSCs.</jats:p