2019-01
Smoothed particle hydrodynamics (SPH) for complex fluid flows: Recent developments in methodology and applications
Ting Ye, Dingyi Pan, Can Huang, and Moubin Liu
Abstract:
Computer modeling of complex fluid flows usually presents great challenges for conventional grid-based numerical methods. Smoothed particle hydrodynamics (SPH) is a meshfree Lagrangian particle method and has special advantages in modeling complex fluid flows, especially those with large fluid deformations, fluid-structure interactions, and multi-scale physics. In this paper, we review the recent developments of SPH in methodology and applications for modeling complex fluid flows. Specifically, in methodology, some important issues including modified SPH particle approximation schemes for improving discretization accuracy, different particle regularization techniques, and various boundary treatment algorithms for solid boundary, free surface, or multiphase interface are described. More importantly, the SPH method with ideas from the dissipative particle dynamics for complex fluids in macro-or meso-scales is discussed. In applications, different complex fluid flows, including biological flows, microfluidics and droplet dynamics, non-Newtonian fluid flows, free surface flows, multiphase flows, and flows with fluid-structure interaction, are reviewed. Some concluding remarks in SPH modeling of complex fluid flows are provided.
Reference:
T. Ye, D.Y. Pan, C. Huang, M.B. Liu, Smoothed particle hydrodynamics (SPH) for complex fluid flows: Recent developments in methodology and applications, Physics of Fluids, 2019, 31: 011301.
2019-01
事件驱动的强化学习多智能体编队控制
Abstract:
针对经典强化学习的多智能体编队存在通信和计算资源消耗大的问题,本文引入事件驱动控制机制,智能体的动作决策无须按固定周期进行,而依赖于事件驱动条件更新智能体动作。在设计事件驱动条件时,不仅考虑智能体的累积奖赏值,还引入智能体与邻居奖赏值的偏差,智能体间通过交互来寻求最优联合策略实现编队。数值仿真结果表明,基于事件驱动的强化学习多智能体编队控制算法,在保证系统性能的情况下,能有效降低多智能体的动作决策频率和资源消耗。
Reference：
徐鹏,谢广明,文家燕,高远.事件驱动的强化学习多智能体编队控制[J].智能系统学报,2019,14(01):93-98.
2019-01-15
High-accuracy transient response fiber optic seismic accelerometer using a shock-absorbing ring as a mechanical antiresonator
Yi, Duo; Liu, Fei; Zhang, Min; Tao, Qingchang
Abstract:
This study proposes a high-accuracy transient response fiber optic seismic accelerometer based on the resonance suppression mechanism. A shock-absorbing ring is embedded in the accelerometer structure, which acts as a mechanical antiresonator. The experimental results show that the sensitivity at the resonance frequency is suppressed by 21.79 dB, and the 3 dB operating bandwidth is extended without reducing the average sensitivity. Under this condition, the high-accuracy transient response is obtained during the vibration-event test. This study provides a practical seismic acquisition technique solution for vertical seismic profiling monitoring in the smart oilfield. (C) 2019 Optical Society of America
Reference:
Duo, Yi, et al. "High-accuracy transient response fiber optic seismic accelerometer using a shock-absorbing ring as a mechanical antiresonator."Optics letters 44.2 (2019): 183-186.
2019-01
An integrated finite particle method with perfectly matched layer for modeling wave-structure interaction
X. Weng, C. Huang, T. Long, S. M. Li and M. B. Liu
Abstract:
Numerical simulation of wave-structure interaction is an important but challenging topic due to the movement, deformation and even breakup of free surface, and strong fluid-structure interaction. The implementation of far-field boundary condition is crucial for numerical simulations of wave-structure interaction to avoid the disturbance of reflected waves. In this paper, an integrated finite particle method (FPM) with perfectly matched layer (PML) is developed for modeling wave-structure interaction problems. The PML uses a fictitious layer based on the concept of physical damping to control the wave reflection in a wave tank. The FPM with PML is first used to model the regular wave propagation and it is found that the obtained numerical results are in good agreement with analytical solutions or existing reference results. It is further proved that PML with a properly selected length of wave tank can effectively remove the traveling waves and reproduce the far-field effects. The FPM with PML is then used to model the oscillating wave surge converter (OWSC). The results show that the time-averaged power of OWSC strongly depends on the PTO damping coefficients, the wave periods and the distance between the OWSCs.
Reference:
X. Weng, C. Huang, T. Long, S. M. Li & M. B. Liu (2019) An integrated finite particle method with perfectly matched layer for modeling wave-structure interaction, Coastal Engineering Journal, 61:1, 78-95.
2019-02
High-resolution reconstruction of sedimentary organic matter variability during the Holocene in the mud area of the Yellow Sea using multiple organic geochemical proxies
Wu, Xiuning，Xing, Le，Jiang, Yiqing，Zhang, Xiaodong，Xiang, Rong and Zhou, Liping
Abstract:
As a result of terrestrial input and local circulation, an area containing continuously deposited mud with abundant organic matter (OM) has formed in the Yellow Sea (YS) off the Shandong Peninsula, China, during the Holocene. The understanding of temporal variations in sedimentary organic matter (SOM) from this mud area helps to evaluate the influences of Yellow River discharge and marine productivity on the burial of organic matter in the YS. In this study, multiple organic geochemical proxies were used to reconstruct Holocene changes in SOM in a sediment core (A02C) recovered from the mud area of the YS. Higher total organic carbon (TOC) and biomarker contents during the early Holocene relative to the middle and late Holocene are attributed to sea-level fluctuations. The delta C-13 values of TOC (delta C-13(TOC)) range from -21.8 parts per thousand to -23.5 parts per thousand, becoming more positive from the bottom to the top of the core. TMBR' (terrestrial and marine biomarker ratio) values vary from 0.43 to 0.80, with a decreasing trend during the Holocene. The decrease in TOM contribution was related to elevated sea-level, shifting of the mouth of the Yellow River, and weakening of the East Asian Winter Monsoon (EAWM) during the Holocene. A mixing model with three end-members, based on delta C-13(TOC) and TMBR', reveals that the contribution of soil OM (average 42%) is higher than that of plant OM (average 17%). Simultaneous decreases in the plant OM fraction and the marine OM fraction occurred around 10.3, 8.2, 5.9, 4.2, and 2.8 kyr BP, corresponding to drift-ice events in the North Atlantic. Spectral analyses also reveal that all three OM fractions exhibit 1015-year periodicity and that the soil and plant OM fractions display 1420-year periodicity, consistent with the 1000-year cycle of solar activity and the 1500-year cycle of the Kuroshio Current (KC), respectively.
Reference:
Wu X, Xing L, Jiang Y, et al. High-resolution reconstruction of sedimentary organic matter variability during the Holocene in the mud area of the Yellow Sea using multiple organic geochemical proxies[J]. Quaternary International, 2018.
2019-03
超疏水小球低速入水空泡研究
黄超, 翁翕, 刘谋斌
Abstract:
物体入水问题是一类复杂的流固耦合问题,具有广泛的工程应用背景.物体在跨越自由液面入水的过程中,在一定的条件下,会向水中卷入空气形成空泡,空泡的运动还可能形成指向物体的射流,从而对物体的受力及其运动过程产生影响.超疏水表面能够在物体入水过程中形成多尺度流固耦合作用,进而影响物体的运动和宏观流动现象.而对于小尺度的小球低速入水问题,表面和界面力往往起主导作用.为了在更广的参数空间获得超疏水小球入水空泡类型和小球的运动特性,采用高速摄影实验方法,研究了半径0.17510 mm的超疏水小球低速入水及空泡动力学行为,获得了小球漂浮振荡、准静态空泡、浅闭合空泡、深闭合空泡和表面闭合空泡5种类型的动力学行为,探讨了这些运动行为与韦伯数We和邦德数Bo之间的关系,并推导了小球漂浮振荡与下沉现象的无量纲关系.研究结果表明:超疏水小球的入水及空泡动力学行为主要与韦伯数We和邦德数Bo有关.在邦德数Bo < O(10-1)范围内,表面张力对流动的影响显著,随着韦伯数We的增大,小球入水及空泡动力学行为依次经历漂浮振荡、准静态闭合、浅闭合、深闭合和表面闭合;在邦德数O(10-1) < Bo < O(1)范围内,漂浮振荡现象不再发生;当邦德数Bo >O(1)后,浅闭合现象也不再发生;小球漂浮振荡与下沉现象的临界关系可以用相似律关系描述.
Reference:
黄超, 翁翕, 刘谋斌. 超疏水小球低速入水空泡研究[J]. 力学学报, 2019, 51(1).
2019-03
Smoothed particle hydrodynamics (SPH) for complex fluid flows: Recent developments in methodology and applications
Ting Ye, Dingyi Pan, Can Huang, and Moubin Liu
Abstract:
Computer modeling of complex fluid flows usually presents great challenges for conventional grid-based numerical methods. Smoothed particle hydrodynamics (SPH) is a meshfree Lagrangian particle method and has special advantages in modeling complex fluid flows, especially those with large fluid deformations, fluid-structure interactions, and multi-scale physics. In this paper, we review the recent developments of SPH in methodology and applications for modeling complex fluid flows. Specifically, in methodology, some important issues including modified SPH particle approximation schemes for improving discretization accuracy, different particle regularization techniques, and various boundary treatment algorithms for solid boundary, free surface, or multiphase interface are described. More importantly, the SPH method with ideas from the dissipative particle dynamics for complex fluids in macro-or meso-scales is discussed. In applications, different complex fluid flows, including biological flows, microfluidics and droplet dynamics, non-Newtonian fluid flows, free surface flows, multiphase flows, and flows with fluid-structure interaction, are reviewed. Some concluding remarks in SPH modeling of complex fluid flows are provided.
Reference:
T. Ye, D.Y. Pan, C. Huang, M.B. Liu, Smoothed particle hydrodynamics (SPH) for complex fluid flows: Recent developments in methodology and applications, Physics of Fluids, 2019, 31: 011301.
2019-04
Radiocarbon in the Maritime Air and Sea Surface Water of the South China Sea
Gao, Pan，Zhou, Liping，Liu, Kexin and Xu, Xiaomei
Abstract:
Radiocarbon (C-14) generated by the thermonuclear tests in the late 1950s to early 1960s has been used as a tracer to study atmospheric and oceanic circulations, carbon exchange between different reservoirs, and fossil fuel emissions. Here we report the first measurements of C-14 in atmospheric CO2 of maritime air collected over the South China Sea (SCS) during July 2014. We also present C-14 of the dissolved inorganic carbon (DIC) in the sea surface water in the same region. Most of the Delta C-14 values of the atmospheric CO2 vary in the range of 15.6 +/- 1.6 parts per thousand-22.0 +/- 1.6 parts per thousand, indicating that the central SCS maritime air is well-mixed and consistent with the clean background air in the Northern Hemisphere. The C-14 values of the DIC ((DIC)-C-14) in the surface seawater vary between 28.3 +/- 2.5 parts per thousand and 40.6 +/- 2.7 parts per thousand, mainly due to the lateral mixing between the SCS and western Pacific. The average surface seawater (DIC)-C-14 is 15.4 +/- 5.1 parts per thousand higher than that of the maritime air (CO2)-C-14. The reversal of the sea-air Delta C-14 gradient occurred at similar to 2000, marking the start of the upper ocean transferring bomb C-14 back to the atmosphere in the SCS.
Reference:
Gao P, Zhou L, Liu K, et al. Radiocarbon in the Maritime Air and Sea Surface Water of the South China Sea[J]. Radiocarbon, 2019, 61(2): 461-472.
2019-04
DMOA-based meroterpenoids with diverse scaffolds from the sponge-associated fungus Penicillium brasilianum
Zhang, Jianping，Wu, Yifan，Yuan, Bochuan，Liu, Dong，Zhu, Kui，Huang, Jian，Proksch, Peter and Lin, Wenhan
Abstract:
Bioinformatics analysis of the synthetic gene clusters in association with the qRT-PCR detection led to speculate a marine derived fungus, Penicillium brasilianum WZXY-m122-9, to be potential to produce meroterpenoids. Chromatographic separation of the EtOAc extract of this fungal strain on a large-scale fermentation resulted in the isolation of six new DMOA-related meroterpenoids, namely brasilianoids G-L (1-6), together with nine known meroterpenes. Their structures were determined by extensive analyses of spectroscopic data, including the X-ray diffraction and the ECD data for configurational assignment. Brasilianoid G is characterized by the presence of an unprecedented scaffold bearing a 6/6/5/5/5 pentacyclic nucleus, while brasilianoid K possessing a 7/6/6/6/5 pentacyclic system is uncommonly found from nature. The biogenetic relationship among the isolated compounds was postulated based on the comparative analyses of gene clusters. Brasilianoid L (6), austinol (12), and dehydroaustin (14) exhibited significant inhibition against bacteria invasion into host cells, that was suggested to be mediated by preventing the polymerization of actin in the host cells. (C) 2019 Elsevier Ltd. All rights reserved.
Reference:
Zhang J, Wu Y, Yuan B, et al. DMOA-based meroterpenoids with diverse scaffolds from the sponge-associated fungus Penicillium brasilianum[J]. Tetrahedron, 2019, 75(14): 2193-2205.
2019-04
面向水下机器人的水下电场通信协议设计
张晗, 王伟, 谢广明
Abstract:
作为一种新型的水下通信方法,电场通信具有能耗低,不易受外界环境干扰,实时性、全向性好等优点,可在小型水下机器人水下通信、组网中发挥良好作用。在前期的研究中,已将电场通信系统集成在一款仿箱鲀机器鱼上。但由于使用的是共享信道,当多机器鱼(节点)通信时,难免出现通信碰撞问题。文中基于无线通信网络载波侦听多路访问/冲突避免(CSMA/CA)协议提出了电场通信协议。介绍了协议的运行机制以及信道状态的检测方法。为验证设计协议的有效性,进行了MATLAB仿真及3条机器鱼电场通信实验。结果表明,该协议能有效减少通信碰撞的发生。
Reference:
张晗,王伟,谢广明.面向水下机器人的水下电场通信协议设计[J].水下无人系统学报,2019,27(02):134-141.
2019-05
Bottom-level motion control for robotic fish to swim in groups: Modeling and experiments
Li, Liang; Liu, Anquan; Wang, Wei; Ravi, Sridhar ; Fu, Rubin; Yu, Junzhi ; Xie, Guangming
Abstract:
Moving in groups is an amazing spectacle of collective behaviour in fish and has attracted considerable interest from many fields, including biology, physics and engineering. Although robotic fish have been well studied, including algorithms to simulate group swimming, experiments that demonstrate multiple robotic fish as a stable group are yet to be achieved. One of the challenges is the lack of a robust bottom-level motion control system for robotic fish platforms. Here we seek to overcome this challenge by focusing on the design and implementation of a motion controller for robotic fish that allows multiple individuals to swim in groups. As direction control is essential in motion control, we first propose a high-accuracy controller which can control a sub-carangiform robotic fish from one arbitrary position/pose (position and direction) to another. We then develop a hydrodynamic-model-based simulation platform to expedite the process of the parameter tuning of the controller. The accuracy of the simulation platform was assessed by comparing the results from experiments on a robotic fish using speeding and turning tests. Subsequently, extensive simulations and experiments with robotic fish were used to verify the accuracy and robustness of the bottom-level motion control. Finally, we demonstrate the efficacy of our controller by implementing group swimming using three robotic fish swimming freely in prescribed trajectories. Although the fluid environment can be complex during group swimming, our bottom-level motion control remained nominally accurate and robust. This motion control strategy lays a solid foundation for further studies of group swimming with multiple robotic fish.
Reference:
Li, Liang; Liu, Anquan; Wang, Wei; Ravi, Sridhar ; Fu, Rubin; Yu, Junzhi ; Xie, Guangming.Bottom-level motion control for robotic fish to swim in groups: Modeling and experiments[J].Bioinspiration and Biomimetics, v 14, n 4, May 2, 2019; ISSN: 17483182, E-ISSN: 17483190; DOI: 10.1088/1748-3190/ab1052.
2019-06
Operational-matrix-based algorithm for differential equations of fractional order with Dirichlet boundary conditions
Usman, M; Hamid, M ; Zubair, T ; Ul Haq, R ; Wang, W
Abstract:
.The fractional differential equations (FDEs) are ground-breaking tools to demonstrate the complex-nature scientific systems in the form of non-linear behavior endorsed by the scientific community to develop some new and accurate mathematical methods. The main objective of this paper is the development of an extended mathematical algorithm based on the Gegenbauer wavelet method for the fractional-order problem. The Gegenbauer wavelet operational matrix with their derivative is proposed in our study. Some new operational matrices for the derivative of fractional order with Dirichlet boundary condition is purposed by introducing the piecewise function. Furthermore, a successful use to analyze the solution for the set of algebraic equations governed through the extended Gegenbauer wavelets technique is performed. Analytical solutions of the mentioned problem are effectively obtained, and a comparative study is presented. The outcomes are obtained via the modified Gegenbauer wavelet method by endorsing the accuracy and effectiveness of the mentioned technique. The convergence and error bound analysis are enclosed in our investigation. It is further verified that the algorithm is quite accurate, and an efficient mathematical tool is used to tackle the nonlinear fractional-order complex-nature problems.
Reference:
Usman, M; Hamid, M ; Zubair, T ; Ul Haq, R ; Wang, W.Operational-matrix-based algorithm for differential equations of fractional order with Dirichlet boundary conditions[J].EUROPEAN PHYSICAL JOURNAL PLUS 卷: 134 期: 6 文献号: 279 出版年: JUN 2019.
2019-07
Three new cyclopiane-type diterpenes from a deep-sea derived fungus Penicillium sp. YPGA11 and their effects against human esophageal carcinoma cells.
Cheng, Zhongbin; Li, Yuanli; Xu, Wei; Liu, Wan; Liu, Lijun; Zhu, Daigui; Kang, Ying; Luo, Zhuhua; Li, Qin
Abstract:
Cyclopianes, featuring a highly rigid 6/5/5/5-fused tetracyclic framework, are structurally unique and biologically significant and belong to a rarely reported diterpenoid family. Chemical investigation of an EtOAc extract of a deep-sea-derived Penicillium sp. led to the isolation of three new cyclopiane diterpenes, namely, conidiogenols C-D (1-2) and conidiogenone L (3). The structures were determined by extensive analyses of the spectroscopic data in association with ECD calculations and chemical conversion for configurational assignments. Compound 1 represents the second example of cyclopianes bearing a hydroxyl group at C-13. Compound 2, the third example of conidiogenols, possesses a distinct alpha-oriented 1-hydroxy group relative to other analogues. The bioassay study demonstrated that compounds 2 and 4-6 exhibited moderate inhibitory effects against five esophageal cancer cell lines with IC50 values ranging from 25 to 55 muM. The cytotoxicities of all compounds toward esophageal cancer cell lines were evaluated for the first time.
Reference:
Cheng, Zhongbin; Li, Yuanli; Xu, Wei; Liu, Wan; Liu, Lijun; Zhu, Daigui; Kang, Ying; Luo, Zhuhua; Li, Qin.Three new cyclopiane-type diterpenes from a deep-sea derived fungus Penicillium sp. YPGA11 and their effects against human esophageal carcinoma cells.[J]Bioorganic chemistry 卷:91 页:103129 出版年: 2019-Jul-20 (Epub 2019 Jul 20).
2019-07
Dual solutions and stability analysis of flow and heat transfer of Casson fluid over a stretching sheet
Hamid, M ; Usman, M ; Khan, ZH ; Ahmad, R ； Wang, W .
Abstract:
The aim of the current study is to find out the dual solutions of the two-dimensional magnetohydrodynamic (MHD) flow of Casson fluid and heat transfer over the stretching sheet. The focus of the study is to examine the linear thermal radiation effects on dual solutions for both the steady and unsteady flow of Casson fluid over the stretching sheet under the influence of uniform magnetic field. The governing equations are formed as system of partial differential equations (PDEs). Using suitable transformations, the system of PDEs are converted into favorable nonlinear system of ordinary differential equations (ODEs). Simulations are performed in Maple 2015 to form the dual solutions in order to achieve the velocity, temperature, skin friction and heat transfer profiles of the Casson fluid over the stretching sheet. It is concluded that the dual solutions for the corresponding model are numerically stable. Furthermore, the upper branch solutions of the Casson fluid profiles are numerically stable as compared to the lower branch solutions. Results indicate that positive Eigen values of the MHD flow of Casson fluid provide stable profiles as compared to the negative Eigen values. It is believed that the current study would provide a base for the dual solution of the other types of the non-Newtonian fluid flows over various categories of surfaces. (C) 2019 Elsevier B.V. All rights reserved.
Reference:
Hamid, M ; Usman, M ; Khan, ZH ; Ahmad, R ； Wang, W .Dual solutions and stability analysis of flow and heat transfer of Casson fluid over a stretching sheet.[J]PHYSICS LETTERS A 卷: 383 期: 20 页: 2400-2408 出版年: JUL 18 2019.
2019-08
Smoothed particle hydrodynamics (SPH) for modeling fluid-structure interactions
Liu, Moubin and Zhang, Zhilang
Abstract:
Fluid-structure interaction (FSI) is a class of mechanics-related problems with mutual dependence between the fluid and structure parts and it is observable nearly everywhere, in natural phenomena to many engineering systems. The primary challenges in developing numerical models with conventional grid-based methods are the inherent nonlinearity and time-dependent nature of FSI, together with possible large deformations and moving interfaces. Smoothed particle hydrodynamics (SPH) method is a truly Lagrangian and meshfree particle method that conveniently treats large deformations and naturally captures rapidly moving interfaces and free surfaces. Since its invention, the SPH method has been widely applied to study different problems in engineering and sciences, including FSI problems. This article presents a review of the recent developments in SPH based modeling techniques for solving FSI-related problems. The basic concepts of SPH along with conventional and higher order particle approximation schemes are first introduced. Then, the implementation of FSI in a pure SPH framework and the hybrid approaches of SPH with other grid-based or particle-based methods are discussed. The SPH models of FSI problems with rigid, elastic and flexible structures, with granular materials, and with extremely intensive loadings are demonstrated. Some discussions on several key techniques in SPH including the balance of accuracy, stability and efficiency, the treatment of material interface, the coupling of SPH with other methods, and the particle regularization and adaptive particle resolution are provided as concluding marks.
Reference:
Moubin L, Zhang Z. Smoothed particle hydrodynamics (SPH) for modeling fluid-structure interactions [J]. Science China: Physics, Mechanics and Astronomy, 2019.
2019-08
Coupling finite difference method with finite particle method for modeling viscous incompressible flows
Huang, C ; Long, T ; Liu, MB
Abstract:
A hybrid approach to couple finite difference method (FDM) with finite particle method (FPM) (ie, FDM-FPM) is developed to simulate viscous incompressible flows. FDM is a grid-based method that is convenient for implementing multiple or adaptive resolutions and is computationally efficient. FPM is an improved smoothed particle hydrodynamics (SPH), which is widely used in modeling fluid flows with free surfaces and complex boundaries. The proposed FDM-FPM leverages their advantages and is appealing in modeling viscous incompressible flows to balance accuracy and efficiency. In order to exchange the interface information between FDM and FPM for achieving consistency, stability, and convergence, a transition region is created in the particle region to maintain the stability of the interface between two methods. The mass flux algorithm is defined to control the particle creation and deletion. The mass is updated by N-S equations instead of the interpolation. In order to allow information exchange, an overlapping zone is defined near the interface. The information of overlapping zone is obtained by an FPM-type interpolation. Taylor-Green vortices and lid-driven shear cavity flows are simulated to test the accuracy and the conservation of the FDM-FPM hybrid approach. The standing waves and flows around NACA airfoils are further simulated to test the ability to deal with free surfaces and complex boundaries. The results show that FDM-FPM retains not only the high efficiency of FDM with multiple resolutions but also the ability of FPM in modeling free surfaces and complex boundaries.
Reference:
Huang, C ; Long, T ; Liu, MB. Coupling finite difference method with finite particle method for modeling viscous incompressible flows[J]. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS 卷: 90 期: 11 页: 564-583 出版年: AUG 20 2019
2019-08
An efficient analysis for N-soliton, Lump and lump-kink solutions of time-fractional (2+1)-Kadomtsev-Petviashvili equationincompressible flows
Hamid, M; Usman, M; Zubair, T ; Ul Haq, R; Shafee, A
Abstract:
Solutions of the nonlinear physical problems are significant and a vital topic in real life while the soliton based algorithms are promising techniques to analyze the solutions of various nonlinear real-world problems. Herein, we are reporting some new soliton solutions including N-soliton, lump and lump-kink for (2+1)-Kadomtsev-Petviashvili of fractional-order a arising in mathematical physics. Multiple exp-function approach and bilinear form has been used to investigate the N-soliton and lump, lump-kink solutions of the discussed fractional-order problem. These methods convert the nonlinear partial differential equations into nonlinear algebraic equation having exponential functions. Furthermore, the method is oriented to the comfort of use and fitness of computer algebra systems and provides a direct and systematical solution procedure which generalizes Hirota's perturbation scheme. Graphical representations (2D and 3D) of few specific presented multiple, lump and lump-kink solutions has been made to show the characteristics of multiple, lumps and lump-kinks as well as significant effects of a are plotted for each solution. Moreover, the amplitude of the waves is examined for various values of space variables in x and y direction as well as particular values of a as time varies. It is noticed that as alpha -> 1the solution turn into three wave and lump-kink solutions which is asserted via set of graphs. The higher values of space variable y are causing a decrease in the amplitude of the wave whereas the higher values of a are providing a higher amplitude of the wave. Hence, the attained results for nonlinear time fractional (2+1)-Kadomtsev-Petviashvili equation are endorsing the efficiency and appropriateness of multiple exp-function to analyze the N-soliton solutions. It is important to highlight that said method could be extended to diversify problem of physical nature. (C) 2019 Elsevier B.V. All rights reserved.
Reference:
Hamid, M; Usman, M; Zubair, T ; Ul Haq, R; Shafee, A.An efficient analysis for N-soliton, Lump and lump-kink solutions of time-fractional (2+1)-Kadomtsev-Petviashvili equationincompressible flows[J]. PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS 卷: 528,文献号: 121320 出版年: AUG 15 2019
2019-08
Thermal management of MHD nanofluid within the porous medium enclosed in a wavy shaped cavity with square obstacle in the presence of radiation heat source
Alkanhal, TA; Sheikholeslami, M ; Usman, M; Rizwan-ul Haq; Shafee, A ; Al-Ahmadi, AS; Tlili, I.
Abstract:
In this manuscript, we present nanofluid thermal management inside a porous media including magnetic force and radiation heat sources. The systems of PDEs were changed into the non-dimensional form by means of the suitable transform. To gain the outputs, control volume finite element method (CVFEM) was utilized. Radiative source term was involved in final PDEs. Isotherms and streamlines are plotted to demonstrate the variation of Hartmann number, radiation factor, buoyancy and nanoparticles' shape on nanofluid behavior. Outputs demonstrate that convective mode becomes stronger with augment of shape factor. By involving source terms of magnetic field, conduction becomes more effective. Average Nusselt number grows as enhancing the shape effect parameters "m", Radiation effect and Raleigh number. As increasing Radiation and Raleigh parameters average temperature deceases gradually. The comparative study is also presented, which shows the reliability and efficiency of the CVFEM. Graphical study also shows strengthen of suggested technique. (C) 2019 Elsevier Ltd. All rights reserved.
Reference:
Alkanhal, TA; Sheikholeslami, M ; Usman, M; Rizwan-ul Haq; Shafee, A ; Al-Ahmadi, AS; Tlili, I.Thermal management of MHD nanofluid within the porous medium enclosed in a wavy shaped cavity with square obstacle in the presence of radiation heat source[J].INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 卷: 139 页: 87-94 出版年: AUG 2019
2019-09
A kernel gradient-free SPH method with iterative particle shifting technology for modeling low-Reynolds flows around airfoils
Huang, C. ; Long, T. ; Li, S.M. ; Liu, M.B.
Abstract:
The conventional SPH method does not perform well for simulating flows around rigid bodies. Especially, it is difficult to get convergent and accurate results when simulating flows around a thin airfoil. The reason is its low accuracy especially for highly irregular particle distributions in the process of SPH simulation of flow around slender structures. In this paper, a kernel gradient-free (KGF) SPH method with iterative particle shifting technology (PST) is proposed for the simulation of flow around the airfoil. KGF-SPH can maintain high accuracy without using kernel gradients. Iterative PST can maintain uniform particle distribution even if the smoothing length is less than the average particle spacing. Lid-driven shear cavity flows, Taylor–Green flow, the stretching of a free-surface circular fluid patch and flows around a cylinder are simulated to test the numerical method. Numerical results are almost in consistent with the analytical or reference results. Finally, flows past an airfoil are simulated by using the proposed SPH method. The results show that the present SPH method effectively improves numerical stability and accuracy for simulating flows around an airfoil.
Reference:
Huang, C. ; Long, T. ; Li, S.M. ; Liu, M.B. A kernel gradient-free SPH method with iterative particle shifting technology for modeling low-Reynolds flows around airfoils[J].Engineering Analysis with Boundary Elements, v 106, p 571-587, September 2019; ISSN: 09557997; DOI: 10.1016/j.enganabound.2019.06.010
2019-09
Obstacle effects on electrocommunication with applications to object detection of underwater robots
Chen, YT ; Wang, W ; Li, L ; Kelly, R; Xie, GM
Abstract:
Some fish species communicate electrically (termed electrocommunication) in turbid waters where other communication modalities fail. Inspired by this biological phenomenon, we have developed an artificial electrocommunication system for underwater robots (Wang et al 2017 Bioinspir. Biomimetics 12 036002). Due to the complex terrain of the ocean, electrocommunication could be affected by potential obstacles. In this paper, we investigate the obstacleeffects on electrocommunication in a quasi-two-dimensional water environment. We first employ Fresnel zone theory to theoretically analyze the obstacleeffects on electrocommunication. We then simplify the ocean terrain into 32 types of obstacles according to their material, relative location, geometry, and size, and use ANSYS Maxwell to simulate the effect of these obstacles on electrocommunication. We fabricate the same types of obstacles as in the simulation, and further conduct electrocommunication experiments with these obstacles in a swimming pool. Both the simulations and experiments show that the material, relative location, geometry, and size of the obstacles all affect the electrocommunication to varying degrees. Finally, we demonstrate that it is possible to identify and detect underwater objects based on the obtained obstacle effects, indicating that electrocommunication could be a new viable method for underwater object detection.
Reference:
Chen, YT ; Wang, W ; Li, L ; Kelly, R; Xie, GM；BIOINSPIRATION & BIOMIMETICS,卷: 14 期: 5,文献号: 056011,DOI: 10.1088/1748-3190/ab336c
2019-10
Three new cyclopiane-type diterpenes from a deep-sea derived fungus Penicillium sp. YPGA11 and their effects against human esophageal carcinoma cells
Cheng, ZB; Li, YL; Xu, W; Liu, W; Liu, LJ; Zhu, DG; Kang, Y; Luo, ZH; Li, Q；
Abstract:
Cyclopianes, featuring a highly rigid 6/5/5/5-fused tetracyclic framework, are structurally unique and biologically significant and belong to a rarely reported diterpenoid family. Chemical investigation of an EtOAc extract of a deep-sea-derived Penicillium sp. led to the isolation of three new cyclopiane diterpenes, namely, conidiogenols C-D (1-2) and conidiogenone L (3). The structures were determined by extensive analyses of the spectroscopic data in association with ECD calculations and chemical conversion for configurational assignments. Compound 1 represents the second example of cyclopianes bearing a hydroxyl group at C-13. Compound 2, the third example of conidiogenols, possesses a distinct alpha-oriented 1-hydroxy group relative to other analogues. The bioassay study demonstrated that compounds 2 and 4-6 exhibited moderate inhibitory effects against five esophageal cancer cell lines with IC50 values ranging from 25 to 55 mu M. The cytotoxicities of all compounds toward esophageal cancer cell lines were evaluated for the first time.
Reference:
Cheng, Zhongbin; Li, Yuanli; Xu, Wei; Liu, Wan; Liu, Lijun; Zhu, Daigui; Kang, Ying; Luo, Zhuhua; Li, Qin. Bioorganic chemistry 卷:91 页:103129 出版年: 2019-Jul-20 (Epub 2019 Jul 20)
2019-10
Innovative operational matrices based computational scheme for fractional diffusion problems with the Riesz derivative
Hamid, M. ; Usman, M. ; Zubair, T.; Haq, R. U. ; Wang, W.
Abstract:
The computational methods based on operational matrices are promising tools to tackle the fractional order differential equations and they have gained increasing interest among the mathematical community. Herein, an efficient and precise computational algorithm based on a new kind of polynomials together with the collocation technique is presented for time-space fractional partial differential equations with the Riesz derivative. The method is proposed with the aid of a new operational matrix of the derivative using Chelyshkov polynomials (CPs) in the Caputo sense. The operational matrices of thederivative, exact and approximate, are derived via two different ways for integer and non-integer orders. The fractional problems under study have been converted into the corresponding nonlinear algebraic system of equations and solved by means of the collocation technique. The convergence and error bound are analyzed for the suggested computational method while a comparative study is included in our work to show the accuracy and efficiency of said method. The attained results confirm that the suggested technique is very accurate, efficient and reliable. As a suitable tool, it could be adopted to obtain thesolutions for a class of the fractional order partial differential (linear and nonlinear) equations arising in engineering and applied sciences.
Reference:
Hamid, M. ; Usman, M. ; Zubair, T.; Haq, R. U. ; Wang, W.EUROPEAN PHYSICAL JOURNAL PLUS,卷: 134 期: 10,文献号: 484,DOI: 10.1140/epjp/i2019-12871-y
2019-11
A smoothed particle element method (SPEM) for modeling fluid-structure interaction problems withlarge fluid deformations
Zhang, ZL (Zhang, Z. L.) ; Long, T (Long, T.); Chang, JZ (Chang, J. Z; Liu, MB (Liu, M. B.)
Abstract:
Fluid-structure interaction (FSI) problems with large fluid deformations can be a great challenge for numerical simulations using conventional methods. In this paper, we propose a novel hybrid approach of an improved Smoothed Particle hydrodynamics and smoothed finite Element Method (SPEM) formodeling FSI problems. In SPEM, the edge-based smoothed finite element method (S-FEM) is developed in Lagrangian frame and is used for the first time to model both elastic structures and incompressible flows. For fluid regions with large deformations, the associated finite elements are adaptively converted into particles and the corresponding regions are subsequently modeled using the decoupled finite particle method (DFPM), which is an improved smoothedparticle hydrodynamics (SPH) method suitable for modeling incompressible flows with free surfaces. A ghost particle-based interface algorithm to couple existing S-FEM elements and DFPM particles is developed in SPEM to implement the modeling of FSI problems. As the smoothed FEM and decoupled FPM are enhanced FEM and SPH respectively and DFPM is only used for local fluid regions with large deformations, it is expected that SPEM is more accurate and more efficient than the existing coupling approaches of conventional FEM and SPH. Five numerical examples are tested using the proposed SPEM and the comparative studies with results from other sources reveal that SPEM is an effective approach for modeling FSI problems with large fluid deformations. (C) 2019 Elsevier B.V. All rights reserved.
Reference:
Zhang, Z. L.; Long, T. ; Chang, J. Z.; Liu, M. B.COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING,卷: 356 页: 261-293,DOI: 10.1016/j.cma.2019.07.024
2019-11
Wavelet investigation of Soret and Dufour effects on stagnation point fluid flow in two dimensionswith variable thermal conductivity and diffusivity
Zhang, Hamid, M (Hamid, Muhammad); Usman, M (Usman, Muhammad); Haq, RU (Haq, Rizwan Ul)
Abstract:
The current analysis is devoted to observing the influence of Soret and Dufour effects on stagnation point fluid flow in two dimensions. The buoyancy effects, variable thermal conductivity and diffusivity are also considered in our study. The governing equations of flow are reduced to a nonlinear ordinary differential equation system via a suitable transformation technique. The numerical simulation is performed by means of a new algorithm based on the Chebyshev wavelet method (MCWM). A detailed assessment of outcomes obtained by MCWM with fourth-order Runge-Kutta technique is available to support our wavelet-based solution. The significant properties and effects of various physical parameters are presented graphically. It is noted that an increase in the values of magnetic parameters cause a decrease in the velocity profile for the assisting case while the behavior of velocity is the opposite for the opposing case. The effects of Soret and Dufour enhanced the temperature and concentration, respectively. The comparison and convergence analysis indicate that the proposed algorithm is an efficient tool and could be extended for other complex nature models in engineering and physics.
Reference:
Hamid, Muhammad; Usman, Muhammad; Haq, Rizwan Ul.PHYSICA SCRIPTA 卷: 94 期: 11,文献号: 115219,DOI: 10.1088/1402-4896/ab2650
2019-12
MHD natural convection and thermal control inside a cavity with obstacles under the radiation effects
M. Usman;Z.H. Khan; M.B. Liu;
Abstract:
Understanding of flow nature inside a close geometry as well as analysis of heat augmentation through fluids has been gaining a vital interest among research community due to industrial and engineering applications. Herein, a model study is conduced to investigate the heat and mass transfer of Magnetohydrodynamic (MHD) flow enclosed a square cavity with top wall is heated. Two heated and two clod square obstacles are placed inside the square cavity. Feasible nondimensional variables are introduced to transform the continuity, momentum and energy equations into nondimensional form. A finite element model is developed and applied to investigate the numerical solutions of nondimensional set of partial differential equations. In order to scrutinize the significant influence of dimensionless parameters on streamlines, isotherms and isoconcentrations simulations are executed when the bottom squares are heated. It is detected that Nusselt numbers increases as enhancing the thermal radiation parameter. Comparison of the achieved results for local and average Nusselt numbers with published results are presented, which are evident that the suggested method is well-matched to examine the solutions of such types of problems and it can be extended for solving diversified problem of physical nature having complex geometry.
Reference:
M. Usman;Z.H. Khan; M.B. Liu.Physica A: Statistical Mechanics and its Applications,卷: 535,DOI: 10.1016/j.physa.2019.122443.
2019-12
Evidence for provenance change in deep sea sediments of the Bengal Fan: A 7 million year recordfrom IODP U1444A
Chang, ZH; Zhou, LP;
Abstract:
Previously published geochemical and mineralogical data have revealed conflicting views on the provenance of the deep-sea sediments in the Bengal Fan. Here we report results of a study for a 330-m sequence consisting of both turbitide and semi-pelagic sediments recovered at the Site U1444A during the IODP 353 Expedition. A novel technique using the optically and thermally stimulated luminescence (OSL and TL) signatures from quartz and K-feldspar has been employed to characterise the mineral compositions of the sediments. We show that the quartz luminescence sensitivity clearly differentiates the four sedimentary units. There is a distinct increase of quartz luminescence sensitivity in Unit 2 during the time interval of similar to 3.5-0.5 Ma. Analyses of the luminescence signal components in quartz and the ratio of the K-feldspar and quartz also point to a change in Unit 2 relative to the other three units. We interpret such changes in the mineralogical compositions through the sequence as reflecting a change in the provenance over the last 7 million years in the western Bengal Fan. We attribute the quartz with enhanced luminescence sensitivity in Unit 2 to the contribution from the sources associated with Indian rivers. We infer that the delivery of the sediments from Indian peninsula to IODP Site U1444A is facilitated by a weakening in the turbidite deposition which is dominated by weathering products from the Himalayas. We speculate that the relatively high elevation of the 85 degrees E Ridge may act against the flow through and the associated deposition of turbidity current originated from the Himalayas.
Reference:
Chang, ZH; Zhou, LP. Evidence for provenance change in deep sea sediments of the Bengal Fan: A 7 million year recordfrom IODP U1444A, JOURNAL OF ASIAN EARTH SCIENCES, 卷：186，DOI:
