船舶与海洋平台结构冰载荷的高性能扩展多面体离散元方法

船舶与海洋平台结构的冰载荷是寒区海洋工程结构物设计中的关键参数,而离散元方法是有效计算结构冰载荷的重要手段. 本文采用基于闵可夫斯基和原理的扩展多面体离散元方法模拟船舶与海洋平台结构的相互作用过程. 其中,构造扩展多面体的近似包络函数并建立了基于优化模型的快速接触搜索算法;考虑单元间粘结作用的刚度软化过程建标识码元间的粘结-破碎模型. 同时,发展了 CPU-GPU 协同异构环境下的高性能并行算法. 为分析海冰与海洋结构作用中的冰载荷,采用ISO标准验证了扩展多面体离散元分析结构冰载荷的准确性. 采用离散元方法计算了船舶结构的冰载荷,研究了船舶结构表明的线载荷分布特点,并采用船舶结构冰阻力经验公式验证了计算结果的合理性. 采用离散元方法计算了平整冰区与多桩腿平台结构的相互作用,分析各桩腿上的冰载荷特点. 针对碎冰区的海冰管理过程,采用离散元方法分析了船舶结构绕行过程中的船舶和海洋平台结构冰载荷. 本文方法可有效应用于海洋结构冰载荷分析,能为极地船舶与海洋平台结构的设计和安全运行提供科学的分析手段.      

Miniaturized surface engineered technologies for multiplex biosensing devices

The demand for quick, accurate, and affordable point-of-care (POC) devices increases with the advancement in the dimensions of nanotechnology and digital interfaces (Internet of Things). The future of diagnostic requires the platform which can provide us the following benefits i. e., on-site detection, qualitative as well as quantitative analysis, easy to use, portable, low sample requirement, cost-effective, and have multiplexing proficiency. Multiplex biosensing platforms (MBPs) have the above following advantages so are going to be mostly used in various healthcare applications in near future. MBPs have the potential to fulfill the ‘ASSURED’ criteria specified by the World Health Organization (WHO) for remote-limited settings. This review paper focuses on miniaturized platforms that have multiplexing benefits for the bioanalysis of different clinical samples related to various healthcare applications. In addition to this, screening of pesticides, antibiotics, and hazardous metal ions with these surface-engineered devices has also been accounted in food and environmental samples. Some of the advanced techniques including microfluidics (Lab-on-a-chip), wearable smart devices, and CRISPR/Cas system for multiplexing applications are briefly described here. Furthermore, various needs, challenges, and prospects in commercializing these multiplexed surface-engineered devices have been discussed in this review.     

Azimuthal Dipolar Rotor Arrays on Surfaces

A set of dipolar molecular rotor compounds was designed, synthesized and adsorbed as self-assembled 2D arrays on Ag(111) surfaces. The title molecules are constructed from three building blocks: (a) 4,8,12-trioxatriangulene (TOTA) platforms that are known to physisorb on metal surfaces such as Au(111) and Ag(111), (b) phenyl groups attached to the central carbon atom that function as pivot joints to reduce the barrier to rotation, (c) pyridine and pyridazine units as small dipolar units on top. Theoretical calculations and scanning tunneling microscopy (STM) investigations hint at the fact that the dipoles of neighboring rotors interact through space through pairs of energetically favorable head-to-tail arrangements.     

考虑设计规范的海洋平台结构选型优化

针对具体海洋环境条件和生产要求，对导管架平台结构进行选型优化——拓扑布局与构件尺寸的联合优化，充分考虑设计规范的要求，建立多设计准则、多约束条件和多荷载工况的设计模型，其中环境荷载包括：风、浪、流、海冰从不同方向对平台的作用。通过结构选型优化获得最佳的结构拓扑布局形式，在降低平台造价的同时，设计出满足结构的稳定特性、安全寿命等多种设计准则的新型平台结构。     

基于Voronoi切割算法的碎冰区构造及离散元分析

离散元方法广泛应用于海冰，特别是碎冰区的动力过程及其对海洋结构作用过程的数值模拟。为构造碎冰区中的冰块几何特性，基于二维Voronoi图方法对计算域进行随机切割以生成碎冰区中冰块的几何形态，并采用球体单元对每个碎冰块单元进行填充，从而确定碎冰区的初始分布场。在采用Voronoi图进行碎冰区构造时，可对冰块尺寸、几何形态和密集度等海冰参数进行设定。为确定冰块的不同几何规则度，综合采用排斥法和扰动法以定量地控制碎冰块几何形态从完全随机分布到规则分布的连续变换。为分析不同几何规则度下碎冰块的几何特性概率分布规律，对计算域内冰块的面积和边数等参数进行统计分析，从而可更合理地参数化控制初始冰场中碎冰块的几何特性。在此基础上，本文基于粘接-破碎的球体离散元方法对不同冰况下锥体结构的冰荷载进行了数值计算，讨论分析了碎冰区的海冰密集度、冰块面积和几何规则度对冰载荷的影响。     

Artificial intelligence-based microfluidic platforms for the sensitive detection of environmental pollutants: Recent advances and prospects

Environmental pollution and its drastic effects on human and animal health have urged governments to implement strict policies to minimize damage. The first step in applying such policies is to find reliable methods to detect pollution in various media, including water, food, soil, and air. In this regard, various approaches such as spectrophotometric, chromatographic, and electrochemical techniques have been proposed. To overcome the limitations associated with conventional analytical methods, microfluidic devices have emerged as sensitive technologies capable of generating high content information during the past few years. The passage of contaminant samples through the microfluidic channels provides essential details about the whole environment after detection by the detector. In the meantime, artificial intelligence is an ideal means to identify, classify, characterize, and even predict the data obtained from microfluidic systems. The development of microfluidic devices with integrated machine learning and artificial intelligence is promising for the development of next-generation monitoring systems. Combination of the two systems ensures time efficient setups with easy operation. This review article is dedicated to the recent developments in microfluidic chips coupled with artificial intelligence technology for the evolution of more convenient pollution monitoring systems.     

Second order wave loads on large monolithic offshore structures

This paper considers the wave loads on large monolithic offshore structures. The second order wave force formulae developed by Rahman and Heaps, applicable to large circular cylinders in waves, are extended to evaluate the overturning moments on large circular cylinders. The theory is then applied to square section caissons in waves, to predict the wave loads on these structures. These calculations are performed using the exact form of the second order velocity potential, φ₂, with arbitrary wave number, k₂, and the approximate form of φ₂, with twice the value of the wave number of the first order velocity potential. The second order analytical predictions are compared with available experimental data for various ranges of wave parameters for both circular and square caissons in large amplitude waves.     

Underwater CCD cameras for PIV flow mapping

Accurate estimation of the forces imposed on offshore structures due to wave and current loading has become more critical due to the introduction of floating production platforms. Work being carried at both Edinburgh and Glasgow Universities aims to measure these effects by force transducer measurements and Particle Image Velocimetry (PIV). A multiple CCD array system is presented which can directly measure accelerations and hence forces acting on offshore structures.     

π‐Plasmon absorbance films of carboxylic functionalized CNTs coupled with renewable PGP platforms

π‐Plasmon absorbance films of carboxylic functionalized multiwall carbon nanotubes (CNTs) coupled with renewable and recycled polycaprolactone grafted pectin (PGP) platforms as successful alternative for ordinary nondegradable platforms were investigated. Characterization of the synthesized carboxylic functionalized CNTs was performed using ¹H NMR and attenuated total reflectance Fourier transform infrared for structural identification, thermogravimetric analysis and derivative thermogravimetric analysis for thermal stability, and X‐ray powder diffraction for crystal structure, whereas the characterization of prepared PGP was done by means of attenuated total reflectance Fourier transform infrared for chemical structure, differential scanning calorimetry for melting endotherms of polycaprolactone and high crystalline structure of PGP, and thermogravimetric analysis and derivative thermogravimetric analysis for thermal stability of PGP. Fabrication of water‐dispersed carboxylic functionalized CNTs coupled with PGP films was performed by casting technique in the presence of Ca²⁺ as cross‐linker. The thin films were tested for π‐plasmon absorbance using UV‐Vis spectrometry. Different fractions of carboxylic functionalized CNTs and PGP films demonstrated π‐plasmon absorbance broad peaks at λ_max = 232 nm, which corresponded to 5.36 eV. The fabrication of novel films from renewable recycled PGP platform and advanced carboxylic functionalized CNTs properties will be the key features for many of next forthcoming technologies. The PGP considered as environment‐friendly and easily degradable platforms will be a successful alternative for conventional nondegradable electronic platforms, and water‐dispersed carboxylic functionalized CNTs with advanced properties will be finding accelerating executive applications.     

Parameterized approximations for the two-sided assortment optimization

We consider the problem faced by an online service platform that matches suppliers with consumers. Unlike traditional matching models, which treat them as passive participants, we allow both sides of the market to exercise their choices. To model this setting, we introduce a two-sided assortment optimization model wherein each participant's choice is modeled using a multinomial logit choice function, and the platform's objective is to maximize its expected revenue. We first show that the problem is NP-hard even when the number of suppliers is limited to two and provide a mixed-integer linear programming formulation. Next, we discuss two simple greedy heuristics and argue that these can lead to arbitrarily bad solutions. We then develop relaxations that provide upper and lower bounds and investigate the tightness of these relaxations by obtaining parametric approximation guarantees. Finally, we present numerical results on synthetic data demonstrating the practical utility of these relaxations.