Zihai Geng^1,2,*, Jinsheng Cai¹, Yubiao Jiang^1,2, Weiguo Zhang^1,2

FDMP-Fluid Dynamics & Materials Processing, Vol.17, No.5, pp. 899-915, 2021, DOI:10.32604/fdmp.2021.012108 - 05 July 2021

Abstract Reducing drag during take-off and nominal (cruise) conditions is a problem of fundamental importance in aeronautical engineering. Existing studies have demonstrated that v-shaped symmetrical riblets can effectively be used for turbulence control, with those with dimensionless depth h⁺ = 15 and dimensionless width s⁺ = 15 having the best drag reduction effect. In the present study, experimental tests have been conducted considering two models of the same size, one with smooth surface, the other with v-shaped riblets of the h⁺ = 15 and s⁺ = 15 type. The results show that for an angle of attack in More >

Thanh Thuong Huynh¹, Tien V. T. Nguyen^2,3, Quoc Manh Nguyen⁴, Trieu Khoa Nguyen^2,*

CMC-Computers, Materials & Continua, Vol.68, No.3, pp. 2913-2923, 2021, DOI:10.32604/cmc.2021.016064 - 06 May 2021

Abstract In this study, we investigated warpage and corner lifting minimization for three-dimensional printed parts generated by macro-size fused deposition modeling (FDM). First, the reasons for warpage were theoretically elucidated. This approach revealed that the thermal deformation and differential volumetric shrinkage of the extruded molten plastic resulted in warpage of FDM parts. In addition, low adhesion between the deposited model and the heated or non-heated printing bed may intensify warpage further. As a next step, initial small-size and medium-size models were used to identify parameters to manage and minimize warpage in a way that would reduce… More >

Al Hussien Seddik Saad^1,*, E. H. Hafez², Zubair Ahmad³

CMC-Computers, Materials & Continua, Vol.67, No.1, pp. 659-674, 2021, DOI:10.32604/cmc.2021.014758 - 12 January 2021

Abstract Steganography has been used to prevent unauthorized access to private information during transmission. It is the scheme of securing sensitive information by concealing it within carriers such as digital images, videos, audio, or text. Current steganography methods are working by assigning a cover file then embed the payload within it by making some modifications, creating the stego-file. However, the left traces that are caused by these modifications will make steganalysis algorithms easily detect the hidden payload. Aiming to solve this issue, a novel, highly robust steganography method based on hacking anti-shoplifting systems has proposed to… More >

Shan Jin^1,2,3, Xiaohong Bai⁴, Wei Luo^1,2,3,*, Li Li⁴, Ruiquan Liao^1,2,3

FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.6, pp. 1229-1242, 2020, DOI:10.32604/fdmp.2020.011051 - 17 December 2020

Abstract With the increasing number of horizontal wells with low pressure, low yield, and water production, the phenomenon of water and liquid accumulation in gas wells is becoming progressively more serious. In order to fix these issues, it is necessary to improve existing drainage and gas recovery technologies, increase the fluid carrying capacity of these wells, and ensure that the bottom-hole airflow has enough energy to transport the liquid to the wellhead. Among the many techniques of drainage and gas recovery, the gas lift has recently become a popular method. In the present study, through the… More >

Bo Liu^1,*, Haoran Li¹, Shuya Liu²

Structural Durability & Health Monitoring, Vol.14, No.3, pp. 249-264, 2020, DOI:10.32604/sdhm.2020.06482 - 14 September 2020

Abstract The buoyancy of groundwater can reduce the foundation bearing capacity and cause the metro tunnels to float as a whole, which threatens the safety of structures seriously. Therefore, uplift piles are set up to improve the structural stability. In this paper, FLAC3D software is used to establish the calculation models of pile foundation. The bearing failure process of uplift piles was simulated to study the influencing factors on single pile load bearing capacity as well as the cooperative work laws of pile groups. The load-displacement curves of pile top under different length-diameter ratios, pile-soil interface… More >

Hao Cheng, Guangsheng Du^*, Meng Zhang, Kun Wang, Wenbin Bai

FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.4, pp. 685-698, 2020, DOI:10.32604/fdmp.2020.09673 - 11 August 2020

Abstract The determination of the circulation for wind turbine blades is an important problem in engineering. In the present study, we develop a specific approach to evaluate the integral that represents mathematically the circulation. First the potentialities of the method are assessed using a two-dimensional NACA64_A17 airfoil as a testbed and evaluating the influence of different integration paths and angles of attack on the circulation value. Then the method is applied to blades with different relative heights in order to provide useful reference data to be used for the optimization and reverse design of wind turbine More >

Lihua Wang^{1, *}, Wenjing Ye¹, Yueting Zhou¹

CMES-Computer Modeling in Engineering & Sciences, Vol.122, No.3, pp. 889-906, 2020, DOI:10.32604/cmes.2020.09013 - 01 March 2020

Abstract The lift force was reported not to be high enough to support the dragonfly’s weight during flight in some conventional investigations, and higher lift force is required for its takeoff. In this study, by employing a thin plate model, impact effect is investigated for the wing deformation in dragonfly flapping during takeoff. The static displacement is formulated to compare with the dynamical displacement caused by impact. The governing equation of motion for the impact dynamics of a dragonfly wing is derived based on Newton’s second law. Separation of variables technique and assumed modes method are More >

Yi Luo^1,*, Erxiu Shi², Yin Feng², Boyun Guo², Liehui Zhang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.121, No.1, pp. 105-122, 2019, DOI:10.32604/cmes.2019.06500

Abstract Development of unconventional tight oil and gas reservoirs such as shale pays presents a huge challenge to the petroleum industry due to the naturally low permeability of shale formations and thus low productivity of oil and gas wells. Shale formations are also vulnerable to the contamination of the water in the drilling and completion fluids, which further reduces reservoir permeability. Although gas-drilling (drilling with gas) has been used to address the issue, several problems such as formation water influx, wellbore collapse, excessive gas volume requirement and hole cleaning in horizontal drilling, still hinder its application.… More >

Wang Yang^1,2, Juanjuan Li¹, Jian Yang^1,3, Lin Wei⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.104, No.6, pp. 471-491, 2015, DOI:10.3970/cmes.2015.104.471

Abstract Harvesting is the most difficult and costly operation in cassava production. Currently, most cassava harvest still depends on manual tools. Effective mechanized harvesters are necessary to improve harvesting quality and reduce production cost. Therefore, it is very important to figure out key information for designing an effective tuber lifting system used in bionic “dig-pull” harvesters. A numerical simulation model of human-stem-tuber-soil system was developed to carry out numerical simulation of manually pulling tuber. Coupling algorithm of Lagrange and smoothed particle hydrodynamics (SPH) was used in the model. Lifting mechanism of experienced farmer was studied at… More >

Y.M. Wang^1,2, Q. Wu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.93, No.1, pp. 17-45, 2013, DOI:10.3970/cmes.2013.093.017

Abstract A new kind of operator-orthogonal wavelet-based element is constructed based on the lifting scheme for adaptive analysis of thin plate bending problems. The operators of rectangular and skew thin plate bending problems and the sufficient condition for the operator-orthogonality of multilevel stiffness matrix are derived in the multiresolution finite element space. A new type of operator-orthogonal wavelets for thin plate bending problems is custom designed with high vanishing moments to be orthogonal with the scaling functions with respect to the operators of the problems, which ensures the independent solution of the problems in each scale. More >