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Critical quality indicators of high-performance polyetherimide(ULTEM)over the MEX 3D printing key generic control parameters:Prospects for personalized equipment in the defense industry

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Defence technology(防务技术) 2025年第1期43卷 150-167页

作者： Nectarios Vidakis Markos Petousis Constantine David Nektarios K.Nasikas Dimitrios Sagris Nikolaos Mountakis Mariza Spiridaki Amalia Moutsopoulou Emmanuel Stratakis dept.of Mechanical Engineering Hellenic Mediterranean UniversityHeraklion 71410Greece dept.of Mechanical Engineering International Hellenic UniversitySerres Campus 62124Greece Division of Mathematics and Engineering Sciences Department of Military SciencesHellenic Army AcademyGR 16673VariAtticaGreece Institute of Electronic Structure and Laser(IESL) Foundation for Research and Technology(FORTH)N.Plastira 100Vassilika Vouton 70013HeraklionCreteGreece Qingdao Innovation and Development Center Harbin Engineering UniversityQingdao 266000China

Additive Manufacturing(AM)can provide customized parts that conventional techniques fail to *** important parameter in AM is the quality of the parts,as a result of the material extrusion 3D printing(3D-P)*** can be very important in defense-related applications,where optimum performance needs to be *** quality of the Polyetherimide 3D-P specimens was examined by considering six control parameters,namely,infill percentage,layer height,deposition angle,travel speed,nozzle,and bed *** quality indicators were the root mean square(Rq)and average(Ra)roughness,porosity,and the actual to nominal dimensional *** examination was performed with optical profilometry,optical microscopy,and micro-computed tomography *** Taguchi design of experiments was applied,with twenty-five runs,five levels for each control parameter,on five *** additional confirmation runs were conducted,to ensure *** equations were constructed to express the quality indicators in terms of the control *** modeling approaches were applied to the experimental data,to compare their efficiency,i.e.,Linear Regression Model(LRM),Reduced Quadratic Regression Model,and Quadratic Regression Model(QRM).QRM was the most accurate one,still the differences were not high even considering the simpler LRM model.

关键词： Polyetherimide(PEI) Material extrusion(MEX) Three-dimensional printing(3D-P) Critical quality indicators(CQIs) Quadratic regression model(QRM) Taguchi

3D tomographic analysis of equatorial plasma bubble using GNSS-TEC data from Indonesian GNSS Network

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Earth and Planetary Physics 2025年第1期9卷 127-136页

作者： Ihsan Naufal Muafiry Prayitno Abadi Teguh N.Pratama Dyah R.Martiningrum Sri Ekawati Yuandhika GWismaya Febrylian FChabibi Gatot HPramono Research Center for Climate and Atmosphere Indonesian National Research and Innovation Agency(BRIN)BandungIndonesia Indonesian Geospatial Information Agency(BIG) JakartaIndonesia dept.of Physics Faculty of ScienceUniversiti Teknologi MalaysiaJohor BahruMalaysia dept.Earth Planet Sci. Hokkaido UniversitySapporoJapan School of Electrical Engineering Telkom UniversityBandungIndonesia

Equatorial Plasma Bubbles(EPBs)are ionospheric irregularities that take place near the magnetic *** most commonly occur after sunset during the equinox months,although they can also be observed during other *** phenomenon significantly disrupts radio wave signals essential to communication and navigation *** national network of Global Navigation Satellite System(GNSS)receivers in Indonesia(>30°longitudinal range)provides an opportunity for detailed EPB *** explore this,we conducted preliminary 3D tomography of total electron content(TEC)data captured by GNSS receivers following a geomagnetic storm on December 3,2023,when at least four EPB clusters occurred in the Southeast Asian *** and extracted TEC depletion with a 120-minute running average were then used as inputs for a 3D tomography *** 2D spatial distribution consistently captured the four EPB clusters over *** tomography results were validated through a classical checkerboard test and comparisons with other ionospheric data sources,such as the Global Ionospheric Map(GIM)and International Reference Ionosphere(IRI)*** of the results demonstrates the capability of the Indonesian GNSS network to measure peak ionospheric *** findings highlight the potential for future three-dimensional research of plasma bubbles in low-latitude regions using existing GNSS networks,with extensive longitudinal coverage.

关键词： EPB Indonesian GNSS Network 3D tomography

A METHOD FOR REDUCING YARN HAIRINESS AT RING SPINNING

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Journal of China textile University(English Edition) 1993年第1期10卷 40-43页

作者：曲丽君周启澄 dept.of text.techn. Shandong Textile Engieering College dept.of text.Eng. China Textile University

In order to improve the quality of yarn,a research was carried out at ring spinning.A modifiedtraveller has been used to reduce the yarn hairiness *** to the statistical analysis ofthe data,it was found that the geome... 详细信息

关键词： balloon balloon controllers hairiness ring spun yarns ring spinning frames traveller

Slip-model Performance for Underexpanded Micro-scale Rocket Nozzle Flows

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Journal of Thermal Science 2007年第3期16卷 223-230页

作者： JoséA.Morí■igo JoséHermidaQuesada Francisco Caballero Requena dept.of Space Programmes dept.of

In aerospace Micro-Electro Mechanical Systems （MEMS）, the characteristic length scale of the flow approaches the molecular mean free path, thus invalidating the continuum description and enforcing the use of particle methods, like the Direct Simulation Monte Carlo （DSMC）, to deal with the non-equilibrium regions. Within the slip-regime （0.01〈Kn〈-0.1） both approaches, continuum and particle-based, seem to behave well in terms of accuracy. The present study summarizes the implementation and results obtained with a 2nO-order slip boundary condition in a Navier-Stokes solver to address the rarefaction near the nozzle walls. Its assessment and application to a cold-gas micro-scale conical nozzle of 300μm throat diameter, discharging into the low-pressure freestream, constitutes the major aim of the work. The slip-model incorporates the velocity slip with thermal creep and temperature jump, thus permitting to deal with non-isothermal flows as well. Results show that the gas experiences an intense rarefaction in the lip vicinity, pointing to the limits of model validity. Furthermore, a strong Mach deceleration is observed, attributed to the rather thick subsonic boundary layer and supersonic bulk heating caused by the viscous dissipation, in contrast with the expansion to occur in large rocket nozzles during underexpanded operation.

关键词： Slip flow MEMS micronozzles

Pressure Wave and Fluid Velocity in a Bend-Mode Inkjet Nozzle with Double PZT Actuators

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Journal of Thermal Science 2013年第1期22卷 29-35页

作者： Sungu Kim Jaeyong Sung Myeong Ho Lee Graduate School Dept.of Mechanical EngineeringSeoulTech dept.of Mechanical and Automotive Engineering SeoulTech

A new concept of bend-mode inkjet nozzle with double PZT (lead zirconate titanate) actuators has been designed and fabricated in the present study. Then the pressure wave and fluid velocity at the nozzle exit have been investigated. The complex pressure behavior inside the channel was solved numerically based on the narrow channel acoustic theory. The two PZTs attached to a rectangular channel were actuated sequentially by setting the waveforms of each PZT to be center-aligned with various pulse widths. As a result, the double PZT actuation is superior to the single PZT actuation in view of strong momentum force and fast dissipation of residual pressure. The maximum fluid velocity at the nozzle exit is observed when the respective pulse widths equal to their optimum pulse widths. The numerical results are supported by the experimental results with the fabricated inkjet device by measuring the speed of meniscus just out of the nozzle.

关键词： double PZT actuators inkjet nozzle narrow channel theory pressure wave sequential actuation

Persisting challenges for performance-based building assessment

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Earthquake Engineering and Engineering Vibration 2014年第S1期13卷 79-94页

作者： B.Bayhan I.Kazaz P.Gulkan dept.of Civil Engineering Bursa Technical University Assistant Professor dept.of Civil Engineering Erzurum Technical University Associate Professor dept.of Civil Engineering Cankaya University Professor

Intense research and refinement of the tools used in performance-based seismic engineering have been made,but the maturity and accuracy of these methods have not been adequately confirmed with actual data from the field. The gap between the assumed characteristics of actual building systems and their idealized counterparts used for analysis is wide. When the randomly distributed flaws in buildings as they exist in urban areas and the extreme variability of ground motion patterns combine,the conventional procedures used for pushover or dynamic response history analyses seem to fall short of reconciling the differences between calculated and observed damage. For emergency planning and loss modeling purposes,such discrepancies are factors that must be borne in mind. Two relevant examples are provided herein. These examples demonstrate that consensus-based analytical guidelines also require well-idealized building models that do not lend themselves to reasonably manageable representations from field data. As a corollary,loss modeling techniques,e.g.,used for insurance purposes,must undergo further development and improvement.

关键词： reinforced concrete building nonlinear analysis performance-based seismic assessment performance limits damage

Paederia foetida- a promising ethno-medicinal tribal plant of northeastern India

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Journal of Forestry Research 2013年第4期24卷 801-808页

作者： Silpi Chandadept.of Pharmacy Jaypee University of Information technology Indira P Sarethy Biplab De Kuldeep Singh dept.of Biotechnology Jaypee Institute of Information Technology dept.of Pharmaceutical Science Assam University dept.of Pharmacy Jaypee University of Information Technology

The northeastern region of India constitutes one of the biodi- versity hotspots of the world. The ethnic groups inhabiting this region practice their distinctive traditional knowledge systems using biodiver- sity for food, shelter and healthcare. Among the less-studied plants, Paederia foetida has been used by various ethnic tribes as food and medicine. Many of its therapeutic properties relate to the gastrointestinal system and suggest its potential utility for gastrointestinal ailments. This is a review of the ethnobotanical uses, phytochemistry and therapeutic properties of P. foetida compiled from various reports. P. foetida is promising as a remedy for life-style related conditions, especially treat- ment of ulcers. Its utility highlights the need for proper evaluation of tribal plants as medicines and the species could be considered for devel- opment of new drugs.

关键词： Paederia foetida Tribal medicine ethnobotany phyto-chemistry therapeutic ulcer

Brillouin expanded time-domain analysis based on dual optical frequency combs

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Light(Science & Applications) 2024年第8期13卷 1534-1544页

作者： Jae Hyeong Youn Kwang Yong Song Sonia Martin-Lopez Miguel Gonzalez-Herraez María R.Fernández-Ruiz dept.of Physics Chung-Ang UniversitySeoulKorea dept.of Electronics Universidad de AlcaláMadridSpain

Brillouin Optical Time-Domain Analysis(BOTDA)is a widely-used distributed optical fiber sensing technology employing pulse-modulated pump waves for local information retrieval of the Brillouin gain or loss *** spatial resolution of BOTDA systems is intrinsically linked to pulse duration,so high-resolution measurements demand high electronic bandwidths inversely proportional to the *** paper introduces Brillouin Expanded Time-Domain Analysis(BETDA)as a modified BOTDA system,simultaneously achieving high spatial resolution and low detection *** two optical frequency combs(OFCs)with different frequency intervals as pump and probe,local Brillouin gain spectra are recorded by their spectral beating traces in an expanded time domain.A 2-cm-long hotspot located in a 230m single-mode fiber is successfully measured in the time domain with a detection bandwidth of less than 100 kHz using dual OFCs with tailored spectral phase,line spacing,and bandwidth.

关键词： pump optical fiber

Analysis of Viscous Heating in a Micro-Rocket Flow and Performance

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Journal of Thermal Science 2008年第2期17卷 116-124页

作者： José A.Moríigo José Hermida Quesada dept.of Space Programmes National Institute for Aerospace Technology dept.of Aerodynamics and Propulsion National Institute for Aerospace technology

Micro-rockets for propulsion of small spacecrafts exhibit significant differences with regard to their macroscale counterparts,mainly caused by the role of the viscous dissipation and heat transfer processes in the micron-sized *** goal of this work is to simulate the transient operation of a micro-rocket to investigate the effects of viscous heating on the flow and performance for four configurations of the expanding gas and wafer *** modelling follows a multiphysics approach that solves the fluid and solid regions fully coupled.A contin- uum-based description that incorporates the effects of gas rarefaction through the micro-nozzle,viscous dissipa- tion and heat transfer at the solid-gas interface is ***-equilibrium is addressed with the implementa- tion of a 2nd-order slip-model for the velocity and temperature at the *** results stress that solid-fluid cou- pling exerts a strong influence on the flowfield and performance as well as the effect of the wafer during the first instants of the transient in micro-rockets made of low and high thermal conductivity materials.

关键词： Micronozzles propulsion MEMS slip flow viscous heating