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  • Open Access


    Multi-Stage Multidisciplinary Design Optimization Method for Enhancing Complete Artillery Internal Ballistic Firing Performance

    Jipeng Xie1,2, Guolai Yang1,*, Liqun Wang1, Lei Li1

    CMES-Computer Modeling in Engineering & Sciences, Vol.140, No.1, pp. 793-819, 2024, DOI:10.32604/cmes.2024.048174

    Abstract To enhance the comprehensive performance of artillery internal ballistics—encompassing power, accuracy, and service life—this study proposed a multi-stage multidisciplinary design optimization (MS-MDO) method. First, the comprehensive artillery internal ballistic dynamics (AIBD) model, based on propellant combustion, rotation band engraving, projectile axial motion, and rifling wear models, was established and validated. This model was systematically decomposed into subsystems from a system engineering perspective. The study then detailed the MS-MDO methodology, which included Stage I (MDO stage) employing an improved collaborative optimization method for consistent design variables, and Stage II (Performance Optimization) focusing on the independent optimization of local design variables and… More >

  • Open Access


    Thermodynamic Investigation with Synergetic Method on Inner Crack Growth Behavior at very High Cycle Fatigue Regime

    Yujia Liu1,2, Bo Xu1, Sen Tang3, Lang Li1, Chao He1, Qingyuan Wang1,2,3, Chong Wang1,2,*

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.27, No.4, pp. 1-1, 2023, DOI:10.32604/icces.2023.010057

    Abstract This paper presents a thermodynamic characterization method for estimating the internal crack growth rate, which has been a puzzle in very high cycle fatigue research. A theoretical approach of surface temperature is established with crack size, initiation site, and time for thin sheet material. Infrared thermography is used to study the inner crack behavior and the heat dissipation phenomenon under 20 kHz vibration loading on high-strength stainless steel. A numerical simulation reveals the consequent temperature elevation on the surfaces by the heat generation at the crack tip and the heat conduction. Ultimately, the internal crack growth rate and final fatigue… More >

  • Open Access


    Thrust Generation and Flow Structure of a Flapping Foil in a Stratified Flow

    Jiadong Wang1, Prabal Kandel1, Jian Deng1,*

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.27, No.3, pp. 1-1, 2023, DOI:10.32604/icces.2023.09788

    Abstract The flapping foils with appropriate locomotion inspired by the high-aspect-ratio appendages from natural animals promise a new technical solution for the propulsion of both aircrafts and marine vehicles. The artificial devices using such a novel thrust system are possibly placed in a stratified flow due to the fact that the stratification is ubiquitous throughout real-world environment. Based on a series of two-dimensional numerical simulations, the propulsive performance and wake structure of a fully-activated flapping foil in a density stratified fluid are investigated in this work. It is found that the hydrodynamic characteristics of flapping foils in the stratified flow show… More >

  • Open Access



    Vijayakumar Thulasi*, Thundil Karuppa Raj Rajagopal

    Frontiers in Heat and Mass Transfer, Vol.4, No.2, pp. 1-5, 2013, DOI:10.5098/hmt.v4.2.3007

    Abstract Researchers across the world are exploring the potential of using diethyl ether as an alternate fuel to meet the stringent emission norms due to the high oxygen content in the fuel. The spray characteristics of any injected fuel are highly influenced by its physical properties. Due to high injection pressure in CI engines the fuel tends to cavitate inside the nozzle greatly. The change in fuel properties will affect the cavitating behavior of the fuel. In this paper computational technique is used to study and compare the internal flow characteristics of a fuel injector for different blends of diethyl ether… More >

  • Open Access


    Flow Regimes in Bubble Columns with and without Internals: A Review

    Ayat N. Mahmood1, Amer A. Abdulrahman1, Laith S. Sabri1,*, Abbas J. Sultan1, Hasan Shakir Majdi2, Muthanna H. Al-Dahhan3

    FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.2, pp. 239-256, 2024, DOI:10.32604/fdmp.2023.028015

    Abstract Hydrodynamics characterization in terms of flow regime behavior is a crucial task to enhance the design of bubble column reactors and scaling up related methodologies. This review presents recent studies on the typical flow regimes established in bubble columns. Some effort is also provided to introduce relevant definitions pertaining to this field, namely, that of “void fraction” and related (local, chordal, cross-sectional and volumetric) variants. Experimental studies involving different parameters that affect design and operating conditions are also discussed in detail. In the second part of the review, the attention is shifted to cases with internals of various types (perforated… More >

  • Open Access



    Emmanuel Maurice Arthur*, Timothy Ayando, Yakubu Ibrahim Seini

    Frontiers in Heat and Mass Transfer, Vol.6, pp. 1-10, 2015, DOI:10.5098/hmt.6.21

    Abstract The combined effects of chemical reaction and viscous dissipation on hydromagnetic mixed convective flow towards a vertical plate embedded in a highly porous medium with radiation and internal heat generation has been examined. The governing boundary layer equations have been transformed to a two-point boundary value problem using a local similarity approach and solved numerically using the Newton Raphson shooting method alongside the Fourth-order Runge - Kutta algorithm. The effects of various embedded parameters on fluid velocity, temperature and concentration have been presented graphically whilst the skin friction coefficient and the rates of heat and mass transfers have been tabulated… More >

  • Open Access


    Analysis of Profile and Unsteady Flow Performance of Variable Base Circle Radius Scroll Expander

    Junying Wei*, Gang Li, Chenrui Zhang, Wenwen Chang, Jidai Wang

    Frontiers in Heat and Mass Transfer, Vol.21, pp. 199-214, 2023, DOI:10.32604/fhmt.2023.041793

    Abstract To study the complex internal flow field variation and output characteristics of a variable base radius scroll expander, this paper uses dynamic mesh techniques and computational fluid dynamics (CFD) methods to perform transient numerical simulations of a variable base radius scroll expander. Analysis of the flow field in the working cavity of a variable base radius scroll expander at different spindle angles and the effect of different profiles, speeds and pressures on the output characteristics of the scroll expander. The results of the study show that due to the periodic blocking of the inlet by the orbiting scroll, the fluid… More >

  • Open Access


    K-Hyperparameter Tuning in High-Dimensional Space Clustering: Solving Smooth Elbow Challenges Using an Ensemble Based Technique of a Self-Adapting Autoencoder and Internal Validation Indexes

    Rufus Gikera1,*, Jonathan Mwaura2, Elizaphan Muuro3, Shadrack Mambo3

    Journal on Artificial Intelligence, Vol.5, pp. 75-112, 2023, DOI:10.32604/jai.2023.043229

    Abstract k-means is a popular clustering algorithm because of its simplicity and scalability to handle large datasets. However, one of its setbacks is the challenge of identifying the correct k-hyperparameter value. Tuning this value correctly is critical for building effective k-means models. The use of the traditional elbow method to help identify this value has a long-standing literature. However, when using this method with certain datasets, smooth curves may appear, making it challenging to identify the k-value due to its unclear nature. On the other hand, various internal validation indexes, which are proposed as a solution to this issue, may be… More >

  • Open Access


    Effects of I-EGR and Pre-Injection on Performance of Gasoline Compression Ignition (GCI) at Low-Load Condition

    Binbin Yang1,*, Leilei Liu1, Yan Zhang1, Jingyu Gong1, Fan Zhang2, Tiezhu Zhang1

    Energy Engineering, Vol.120, No.10, pp. 2233-2250, 2023, DOI:10.32604/ee.2023.028898

    Abstract Gasoline compression ignition (GCI) has been considered as a promising combustion concept to yield ultra-low NOX and soot emissions while maintaining high thermal efficiency. However, how to improve the low-load performance becomes an urgent issue to be solved. In this paper, a GCI engine model was built to investigate the effects of internal EGR (i-EGR) and pre-injection on in-cylinder temperature, spatial concentration of mixture and OH radical, combustion and emission characteristics, and the control strategy for improving the combustion performance was further explored. The results showed an obvious expansion of the zone with an equivalence ratio between 0.8~1.2 is realized… More >

  • Open Access


    Quantitative Detection of Corrosion State of Concrete Internal Reinforcement Based on Metal Magnetic Memory

    Zhongguo Tang1, Haijin Zhuo1, Beian Li1, Xiaotao Ma2, Siyu Zhao2, Kai Tong2,*

    Structural Durability & Health Monitoring, Vol.17, No.5, pp. 407-431, 2023, DOI:10.32604/sdhm.2023.026033

    Abstract Corrosion can be very harmful to the service life and several properties of reinforced concrete structures. The metal magnetic memory (MMM) method, as a newly developed spontaneous magnetic flux leakage (SMFL) non-destructive testing (NDT) technique, is considered a potentially viable method for detecting corrosion damage in reinforced concrete members. To this end, in this paper, the indoor electrochemical method was employed to accelerate the corrosion of outsourced concrete specimens with different steel bar diameters, and the normal components BBz and its gradient of the SMFL fields on the specimen surfaces were investigated based on the metal magnetic memory (MMM) method.… More >

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