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复合固体推进剂的综合点火模型

固体火箭技术 1985年第1期11卷 13-21页

作者： a.k.kulkarni 周苏云

本文提出了固体推进剂点火的一种综合理论模型。这种模型可真实地描述非均质推进剂的点火,其中包括环境气体中压力增量(dp/dt)的影响,它还详细地考虑了AP/PBAA推进剂的反应动力学,而且并没有预先做出关于点火部位的假设。其物理模型假... 详细信息

本文提出了固体推进剂点火的一种综合理论模型。这种模型可真实地描述非均质推进剂的点火,其中包括环境气体中压力增量(dp/dt)的影响,它还详细地考虑了AP/PBAA推进剂的反应动力学,而且并没有预先做出关于点火部位的假设。其物理模型假设为嵌入燃料粘结剂模型中的是圆球形氧化剂粒子。数学模型的组成是:(a)氧化剂和燃料粘结剂在固相时的能量方程;(b)质量、能量和物质处在气相时的守恒方程。由试验测得的靠近推进剂试样表面的压力——时间曲线作为模型的输入参数。反应机理需要考虑处在气相中的五种物质。本文研究了表面下的反应和气相反应。它提出的模型能够作为阐述在大范围工作条件下不同推进剂的点火模型的基准。

关键词：推进剂药柱氧化剂固相气相固体推进剂固体火箭推进剂复合推进剂数学物理方程能量方程点火模型

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固体推进剂点火研究评述

固体火箭技术 1987年第2期 36-38页

作者： a.k.kulkarni M.kumar k.k.kuo 王慧

为了确定最新的固体推进剂点火工艺,对有关点火方面的文献作了广泛的评述,严格地检查了各种点火理论、实验方法和点火准则,并以简明的表格形式进行了总结,便于对各种不同的研究作比较。讨论了各种重要参数对点火过程的影响,指出了技术... 详细信息

为了确定最新的固体推进剂点火工艺,对有关点火方面的文献作了广泛的评述,严格地检查了各种点火理论、实验方法和点火准则,并以简明的表格形式进行了总结,便于对各种不同的研究作比较。讨论了各种重要参数对点火过程的影响,指出了技术上的主要不足之处,以及今后的研究方向。

关键词：固体推进剂点火点火延迟化学点火器

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固体推进剂点火研究评论

固体火箭技术 1981年第4期 27-60页

作者： a.k.kulkarni M.kumar k.k.kuo 陈汉君美宾夕法尼亚大学机械工程系美宾夕法尼亚大学机械工程系美宾夕法尼亚大学机械工程系

为了确定固体推进剂点火的现有技术水平,本文对该领域的有关文献作了广泛评论,对各种点火理论、实验测量和点火准则作了详细评定研究。为易于进行比较,本文用易懂的表格形式概括了各项研究工作的情况,也讨论了各种重要参数对点火过程的... 详细信息

为了确定固体推进剂点火的现有技术水平,本文对该领域的有关文献作了广泛评论,对各种点火理论、实验测量和点火准则作了详细评定研究。为易于进行比较,本文用易懂的表格形式概括了各项研究工作的情况,也讨论了各种重要参数对点火过程的影响。指出了主要技术难点,同时提出了进一步研究的建议。

关键词：点火准则表面温度固相推进剂点火点火延迟点火理论燃烧理论环境氧化剂复合推进剂

一个包括气相和亚表面反应的过氯酸铵复合推进剂的点火模型

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固体火箭技术 1983年第2期 78-90页

作者： M.kumar J.E.Willis a.k.kulkarni k.k.kuo 蹇泽群 The Pennsylvania State Univ

本文提出了 Ap 基复合推进剂点火的一个综合模型及其数值解。这一分析模拟位于滞止区的推进剂试样在快速加压条件下的点火过程。本模型的特点包括:a)考虑了 Ap 基复合推进剂点火的详细的化学动力学资料;b)推进剂几何形状是二维(轴对称)... 详细信息

本文提出了 Ap 基复合推进剂点火的一个综合模型及其数值解。这一分析模拟位于滞止区的推进剂试样在快速加压条件下的点火过程。本模型的特点包括:a)考虑了 Ap 基复合推进剂点火的详细的化学动力学资料;b)推进剂几何形状是二维(轴对称)的;c)考虑了气相中压力迅速增加对点燃过程的影响。使用隐式有限差分格式求解瞬态二阶联立、非齐次、非线性偏微分控制方程组。数值解揭示在点火阶段顺序发生的一系列重要事件,包括:点火器气体流入接近样品表面的区域;压缩波到达处未燃成份的燃烧;向推进剂传热;氧化剂和燃烧剂的高温分解;气相反应导致点燃。这个模型正确地预测了实验观察到的现象:随着增压速率提高,点火延迟时间缩短。采用文中考虑的不同点火准则都得到和试验一样的趋势。

关键词：复合推进剂氧化剂点火模型点火延迟推进剂点火点火准则燃烧剂气相表面反应

Study of the Diffusion Behavior of Seawater Absorption in Multi-Walled Carbon Nanotubes/Halloysite Nanotubes Hybrid Nanofillers Modified Epoxy-Based Glass/Carbon Fiber Composites

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Modern Mechanical Engineering 2024年第2期14卷 25-38页

作者： Praful Choudhari Vivek kulkarni Sanjeevakumar khandal Department of Mechanical Engineering Sanjay Ghodawat University Atigre Kolhapur Maharashtra India

In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in harsh seawater conditions is a concern. Researchers address this by exploring three approaches: coating fiber surfaces, hybridizing fibers and matrices with or without nanofillers, and interply rearrangement. This study focuses on evaluating the synergistic effects of interply rearrangement of glass/carbon fibers and hybrid nanofillers, specifically Multi-walled carbon nanotubes (MWCNT) and Halloysite nanotubes (HNT). The aim is to enhance impact properties by minimizing moisture absorption. Hybrid nanocomposites with equal-weight proportions of two nanofillers: 0 wt.%, 1 wt.%, and 2 wt.% were exposed to seawater for 90 days. Experimental data was subjected to modelling through the application of Predictive Fick’s Law. The study found that the hybrid composite containing 2 wt.% hybrid nanofillers exhibited a 22.10% increase in impact performance compared to non-modified counterparts. After 90 days of seawater aging, the material exhibited enhanced resistance to moisture absorption (15.74%) and minimal reduction in impact strength (8.52%) compared to its dry strength, with lower diffusion coefficients.

关键词： Glass/Carbon Fiber Hybrid Composites Multiwall Carbon Nanotubes (MWCNTs) Halloysite Nanotubes (HNTs) Diffusion Behaviour Impact Properties Seawater Aging

Effect of kiwiBiotic on functional constipation and related symptoms:A prospective,single-center,randomized,comparative,crossover study

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World Journal of Gastrointestinal Pharmacology and Therapeutics 2024年第5期15卷 40-49页

作者： Ashwin D Porwal Paresh M Gandhi Deepak k kulkarni Gajanan B Bhagwat Pravin P kamble Department of Proctology Healing Hands ClinicMahārāshtraPune 411001India R&D Center Healing Hands and Herbs Pvt.Ltd.MahārāshtraPune 411002India

BACkGROUND Functional constipation(FC)is a common gastrointestinal disorder characterized by abdominal pain and bloating,which can greatly affect the quality of life of *** treatments often yield suboptimal results,leading to the exploration of alternative therapeutic *** To evaluate the efficacy of kiwiBiotic in the management of FC and related *** This prospective,interventional,single-center,crossover study compared the safety and effectiveness of kiwiBiotic®vs psyllium husk in managing FC,abdominal pain,and *** diagnosed with FC were randomly assigned to receive kiwiBiotic or psyllium husk during the two treatment periods,with a 14-day washout period between *** Seventy participants were enrolled,32 of whom received kiwiBiotic followed by psyllium husk,and 33 received *** showed superiority over psyllium husk in alleviating abdominal pain and bloating,as evidenced by significantly lower mean ***,kiwiBiotic resulted in more than 90.0%of patients experiencing relief from various constipation symptoms,while psyllium husk showed comparatively lower *** kiwiBiotic is an effective treatment option for FC,abdominal pain,and bloating,highlighting its potential as a promising alternative therapy for patients with FC and its associated symptoms.

关键词： kiwiBiotic Psyllium husk Constipation Abdominal pain Bloating

Aqueous-phase reforming of hydroxyacetone solution to bio-based H_(2)over supported Pt catalysts

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Green Energy & Environment 2024年第4期9卷 777-788页

作者： A.k.k.Vikla k.koichumanova Songbo He k.Seshan Joint International Research Laboratory of Circular Carbon Nanjing Tech UniversityNanjing211816China Faculty of Science and Technology University of Twente7500 AE EnschedeThe Netherlands CoRe Pro 9723 BL GroningenThe Netherlands

Aqueous-phase reforming(APR)is an attractive process to produce bio-based hydrogen from waste biomass streams,during which the catalyst stability is often challenged due to the harsh reaction *** this work,three Pt-based catalysts supported on C,AlO(OH),and ZrO_(2)were investigated for the APR of hydroxyacetone solution in afixed bed reactor at 225℃and 35 *** them,the Pt/C catalyst showed the highest turnover frequency for H_(2)production(TOF of 8.9 molH_(2)molPt^(-1)min^(-1))and the longest catalyst *** the AlO(OH)and ZrO_(2)supported Pt catalysts,the side reactions consuming H_(2),formation of coke,and Pt sintering result in a low H_(2)production and the fast catalyst *** proposed reaction pathways suggest that a promising APR catalyst should reform all oxygenates in the aqueous phase,minimize the hydrogenation of the oxygenates,maximize the WGS reaction,and inhibit the condensation and coking reactions for maximizing the hydrogen yield and a stable catalytic performance.

关键词： APR Hydroxyacetone TOF Bio-based H_(2) Support effect

Direct scaling of residual displacements for bilinear and pinching oscillators

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 129-149页

作者： Mohammad Saifullah Vinay k.Gupta Department of Civil Engineering Indian Institute of Technology KanpurKanpur 208016India

The estimation of residual displacements in a structure due to an anticipated earthquake event has increasingly become an important component of performance-based earthquake engineering because controlling these displacements plays an important role in ensuring cost-feasible or cost-effective repairs in a damaged structure after the *** attempt is made in this study to obtain statistical estimates of constant-ductility residual displacement spectra for bilinear and pinching oscillators with 5%initial damping,directly in terms of easily available seismological,site,and model *** of the available models for the bilinear and pinching oscillators are useful when design spectra for a seismic hazard at a site are not *** statistical estimates of a residual displacement spectrum are proposed in terms of earthquake magnitude,epicentral distance,site geology parameter,and three model parameters for a given set of ductility demand and a hysteretic energy capacity coefficient in the case of bilinear and pinching models,as well as for a given set of pinching parameters for displacement and strength at the breakpoint in the case of pinching model *** proposed scaling model is applicable to horizontal ground motions in the western *** earthquake magnitudes less than 7 or epicentral distances greater than 20 km.

关键词： residual displacement spectrum bilinear hysteresis model pinching hysteresis model nonlinear analysis scaling model

Analysis of the Oscillatory Flows of Multiple Shock Waves in a Constant Area Duct

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Journal of Thermal Science 2024年第3期33卷 794-806页

作者： k JAMES Jintu kIM Heuy Dong Department of Mechanical Engineering Andong National UniversityAndong36729Republic of Korea CAD-IT korea Co. Ltd.Seoul08591Republic of Korea

The oscillatory response of multiple shock waves to downstream perturbations in a supersonic flow is studied numerically in a rectangular *** shock waves are formed inside the duct at a shock Mach number of *** duct has an exit height of H,and the effect of duct resonance on multiple shock oscillations is investigated by attaching exit ducts of lengths 0H,50H,and *** downstream disturbance frequency varied from 10 Hz to 200 Hz to explore the oscillation characteristics of the multiple shock *** oscillatory response of shock waves under self-excited and forced oscillation conditions are analyzed in terms of wall static pressure,shock train leading-edge location,shock train length,and the size of the separation *** extent of the initial shock location increases with an increase in exit duct length for the self-excited oscillation *** analysis of the shock train leading edge and the spectral analysis of wall static pressure variations are *** variation in the shock train length is analyzed using the pressure ratio method for self-excited as well as forced *** RMS amplitude of the normalized shock train length(ζ_(ST))increases with an increase in the exit duct length for the self-excited oscillation *** the downstream perturbation frequency is increased,ζ_(ST)is decreased for exit duct *** all exit duct designs and downstream forcing frequencies,the size of the separation bubble grows and shrinks during the shock oscillations,demonstrating the dependence on duct resonance and forced oscillations.

关键词： shock train downstream disturbance supersonic flow shock wave boundary layer interaction duct resonance flow separation