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  • Open Access


    An Adaptive Parallel Feedback-Accelerated Picard Iteration Method for Simulating Orbit Propagation

    Changtao Wang, Honghua Dai*, Wenchuan Yang

    Digital Engineering and Digital Twin, Vol.1, pp. 3-13, 2023, DOI:10.32604/dedt.2023.044210

    Abstract A novel Adaptive Parallel Feedback-Accelerated Picard Iteration (AP-FAPI) method is proposed to meet the requirements of various aerospace missions for fast and accurate orbit propagation. The Parallel Feedback-Accelerated Picard Iteration (P-FAPI) method is an advanced iterative collocation method. With large-step computing and parallel acceleration, the P-FAPI method outperforms the traditional finite-difference-based methods, which require small-step and serial integration to ensure accuracy. Although efficient and accurate, the P-FAPI method suffers extensive trials in tuning method parameters, strongly influencing its performance. To overcome this problem, we propose the AP-FAPI method based on the relationship between the parameters and the convergence speed leveraging… More >

  • Open Access



    Kun Zhang*, Liang Bi Wang

    Frontiers in Heat and Mass Transfer, Vol.7, pp. 1-7, 2016, DOI:10.5098/hmt.7.18

    Abstract Detailed numerical analysis is presented for the effect of spaceship orbital transfer on solution convection during protein crystal growth under microgravity. The results show that the flow and mass transfer during protein crystal growth are unsteady in the process of orbital transfer. For the case of quasi-steady acceleration, the flow is so weak that the effect of flow on concentration field can be negligible. For the case of position adjustment, the convection is enhanced with protein crystal diameter dc > 0.2 mm and slightly alters the purely diffusive concentration distribution under zero gravity condition. For the case of motor working,… More >

  • Open Access


    Collocation-Based Reconstruction Harmonic Balance Method for Solving Periodic Orbits of Aerospace Vehicles

    Zipu Yan1,2, Honghua Dai1,2,*, Xiaokui Yue1,2

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.26, No.3, pp. 1-1, 2023, DOI:10.32604/icces.2023.09138

    Abstract As a significant research interest in orbital mechanics, periodic orbits are fundamental for understanding orbital behaviors and space explorations. Although the harmonic balance (HB) method and its variants have been the most widely-used approaches for periodic dynamical systems, they are seldom applied to celestial dynamics. Here we use the reconstruction harmonic balance (RHB) method for solving periodic orbits. Starting from a presupposed Fourier form and an initial guess at the solution, the algorithm uses timedomain collocation points to optimally reconstruct the high-order HB procedure without complicated symbolic operations and non-physical solutions. Following a description of the method, it is applied… More >

  • Open Access



    Kevin W. Iricka , Sally M. Smithb , Andrew D. Williamsb,* , Derek W. Hengeveldc , Joy M. Steinb

    Frontiers in Heat and Mass Transfer, Vol.12, pp. 1-5, 2019, DOI:10.5098/hmt.12.30

    Abstract This paper provides an analysis of the thermal performance of aerogel insulation used during a long-term International Space Station (ISS) flight experiment aboard Space Test Program – Houston 3 (STP-H3). The Variable emissivity device Aerogel insulation blanket, Dual zone thermal control Experiment suite for Responsive space (VADER) investigation tested a variable emissivity radiator and a new form of multi-layer insulation that used aerogel as the thermal isolator. An effort was made to evaluate the performance of the aerogel insulation over the active flight period. The available flight temperature data shows no evidence of deterioration or change in the aerogel insulation’s… More >

  • Open Access



    Brenton S. Tafta,*, Kevin W. Irickb

    Frontiers in Heat and Mass Transfer, Vol.12, pp. 1-7, 2019, DOI:10.5098/hmt.12.24

    Abstract On September 7th, 2017 the U.S. Air Force Research Laboratory launched the second Advanced Structurally Embedded Thermal Spreader (ASETSII) flight experiment to space on Orbital Test Vehicle 5. The ASETS-II experiment is made of three low-mass, low-cost oscillating heat pipes (OHPs) and an electronics/experiment control box. The three primary science objectives of the experiment are to measure the initial on-orbit thermal performance, to measure long duration thermal performance, and to assess any lifetime degradation. The three OHPs on ASETS-II are of varying configuration (center heating with single- and double-sided cooling) and working fluids (butane and R-134a) in order to isolate… More >

  • Open Access


    Role of Calcination Temperature on Isosorbide Production from Sorbitol Dehydration over the Catalyst Derived from Ce(IV) Sulfate

    Medta Boupan1,2, Kanyapak Prompang1, Achiraya Chompunuch1, Piwat Boonma1, Arthit Neramittagapong1,2,3,4, Somnuk Theerakulpisut5, Sutasinee Neramittagapong1,2,3,*

    Journal of Renewable Materials, Vol.11, No.7, pp. 2985-3000, 2023, DOI:10.32604/jrm.2023.026397

    Abstract Isosorbide is a multi-purpose chemical that can be produced from renewable resources. Specifically, it has been investigated as a replacement for toxic bisphenol A (BPA) in the production of polycarbonate (PC). In this study, the synthesis of isosorbide by sorbitol dehydration using a cerium-based catalyst derived from calcined cerium (IV) sulfate (300°C, 400°C, 450°C, 500°C, and 650°C) was investigated. The reaction occurred in a high-pressure reactor containing nitrogen gas. Advanced instrumental techniques were applied to analyze the characteristics of the calcined catalyst. The results showed that the calcined catalysts demonstrated different crystalline structures and sulfate species at different temperatures. However,… More > Graphic Abstract

    Role of Calcination Temperature on Isosorbide Production from Sorbitol Dehydration over the Catalyst Derived from Ce(IV) Sulfate

  • Open Access


    Low Altitude Satellite Constellation for Futuristic Aerial-Ground Communications

    Saifur Rahman Sabuj1, Mohammad Saadman Alam2, Majumder Haider2, Md Akbar Hossain3, Al-Sakib Khan Pathan4,*

    CMES-Computer Modeling in Engineering & Sciences, Vol.136, No.2, pp. 1053-1089, 2023, DOI:10.32604/cmes.2023.024078

    Abstract This paper discusses the significance and prospects of low altitude small satellite aerial vehicles to ensure smooth aerial-ground communications for next-generation broadband networks. To achieve the generic goals of fifthgeneration and beyond wireless networks, the existing aerial network architecture needs to be revisited. The detailed architecture of low altitude aerial networks and the challenges in resource management have been illustrated in this paper. Moreover, we have studied the coordination between promising communication technologies and low altitude aerial networks to provide robust network coverage. We talk about the techniques that can ensure userfriendly control and monitoring of the low altitude aerial… More > Graphic Abstract

    Low Altitude Satellite Constellation for Futuristic Aerial-Ground Communications

  • Open Access


    Improved Beam Steering Method Using OAM Waves

    Nidal Qasem*, Ahmad Alamayreh

    Computer Systems Science and Engineering, Vol.46, No.1, pp. 417-431, 2023, DOI:10.32604/csse.2023.035603

    Abstract Orbital Angular Momentum (OAM) is an intrinsic feature of electromagnetic waves which has recently found many applications in several areas in radio and optics. In this paper, we use OAM wave characteristics to present a simple method for beam steering over both elevation and azimuth planes. The design overcomes some limitations of traditional steering methods, such as limited dynamic range of steering, the design complexity, bulky size of the steering structure, the limited bandwidth of operation, and low gain. Based on OAM wave characteristics, the proposed steering method avoids design complexities by adopting a simple method for generating the OAM-carrying… More >

  • Open Access


    Multiple Recurrence of Primary Orbital Synovial Sarcoma: Report of Two Cases and Literature Review

    Yi Wu, Yujiao Wang, Weimin He*

    Oncologie, Vol.24, No.4, pp. 927-935, 2022, DOI:10.32604/oncologie.2022.026720

    Abstract Synovial sarcoma (SS) is typically an aggressive malignant soft tissue tumor that mostly affects adolescents and young adults. It is extremely rare in orbit and carries a high risk of recurrence and metastasis, posing a challenge to ophthalmologists in diagnosing and managing. We present two primary orbital synovial sarcoma cases with unilateral exophthalmos and limited motility. Both male patients underwent reoperation in our hospital since tumor recurrence; the pathologic diagnoses were biphasic type and occult type, respectively. Both cases were positive for EMA and CK, and SOX-9 and INI-1 were newly discovered immune markers. Fluorescence in situ hybridization analysis (FISH)… More >

  • Open Access


    Generation of OAM Waves and Analysis of Mode Purity for 5G Sub-6 GHz Applications

    Shehab Khan Noor1, Arif Mawardi Ismail1, Mohd Najib Mohd Yasin1,*, Mohamed Nasrun Osman1, Nurulazlina Ramli2, Ali H. Rambe3, J. Iqbal4,5

    CMC-Computers, Materials & Continua, Vol.74, No.1, pp. 2239-2259, 2023, DOI:10.32604/cmc.2023.031170

    Abstract This article presents the generation of Orbital Angular Momentum (OAM) vortex waves with mode 1 using Uniform Circular Array (UCA) antenna. Two different designs, namely, UCA-1 (4-element array antenna) and UCA-2 (8-element array antenna), were designed and fabricated using FR-4 substrate to generate OAM mode 1 at 3.5 GHz (5G mid-band). The proposed antenna arrays comprised rectangular microstrip patch elements with inset fed technique. The elements were excited by a carefully designed feeding phase shift network to provide similar output energy at output ports with desired phase shift value. The generated OAM waves were confirmed by measuring the null in… More >

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