雷达吸波结构机理分析及电磁设计方法研究

系统地进行了单向和多向碳纤维层板，多向有耗SiC铺层板，加入吸收剂的纺织纤维雷达反射特性，电磁参数预测方法的研究，完成了预测软件，理论计算结果与实验验证吻合较好；独立开发出了浸渍吸收剂蜂窝板的反射系数和等效电磁参数预测的关键技术，包括研究加入有耗介质的蜂窝结构散射电场的计算和电磁参数预测，完成了预测软件，将遗传算法用于宽频带多层吸波材料的优化设计和电路模拟吸波材料的设计方案探索，进行了吸波结构异波板的机理分析和电磁设计，吸收表面波涂层材料的研究，提出了涂层中表面波的吸波机理分析和设计方法。     

紫外吸收剂对硅橡胶力学和表面性能的影响研究

硅橡胶在使用过程中易受紫外辐照作用发生老化,从而影响表面结构和性能。在硅橡胶中加入3种紫外线吸收剂UV-327、UV-531及UVP-788,研究了不同种类及不同用量的紫外吸收剂对硅橡胶及其老化过程的力学性能及表面自由能的影响。结果表明:加入紫外吸收剂对硅橡胶样品的拉伸强度、断裂伸长率及邵氏硬度具有较大的影响,其中加入1份紫外吸收剂的硅橡胶的综合力学性能较好;在紫外辐照720h后,未添加紫外吸收剂的硅橡胶表面自由能由原来的20.7mJ/m~2激增到67.0mJ/m~2,其中酸性分量γ+s和碱性分量γ-s均大幅度增加,而加入1份紫外吸收剂的硅橡胶的表面自由能只有小幅度增加,其中加入UV-327和UV-531具有较好的效果。     

蜂窝式构件长细比的计算方法

为了进一步研究蜂窝构件稳定承载性能,以现有长细比计算理论为基础,结合蜂窝构件的受力机理和界面特性,提出了蜂窝构件长细比计算中相关参数的计算方法．同时,结合理论推导和数值分析结果,提出了蜂窝构件换算长细比建议计算公式．     

蜂窝板传热元件的数值模拟

应用CFD软件FLUENT对蜂窝板传热元件板间空气的三维流动进行了数值模拟,对中心间距为19mm的蜂窝板传热元件在不同质量流量情况下的换热和阻力特性进行了计算分析,给出了在300〈Re〈5000范围内Re与Nu和Re与阻力系数．厂关系的拟合公式,采用同样的方法,对平板以及蜂窝中心间距为19mm、25mm和38mm的蜂窝板进行了对比数值模拟,对4种传热元件换热性能和阻力性能进行了比较．结果表明,在研究的参数范围内,蜂窝板的换热性能比平板的好,而平板的阻力性能较好：3种蜂窝板中,中心间距为38mm的蜂窝板换热性能和阻力性能都较好．     

热防护用轻质烧蚀材料现状与发展

针对我国航天器对热防护系统轻量化的需求,系统总结了国内外轻质热防护烧蚀材料的研究进展及实际应用现状,主要包括蜂窝填充橡胶或树脂、树脂浸渍纤维化多孔基体两类材料,重点介绍了玻璃纤维/酚醛或碳纤维/酚醛蜂窝填充硅橡胶、硅树脂或酚醛树脂和硅树脂浸渍可重复使用陶瓷基体烧蚀材料和酚醛浸渍碳基体烧蚀材料,总结了轻质烧蚀材料的发展趋势和对我国在该领域发展的借鉴意义。     

蜂窝型催化剂的流体阻力和入口效应

蜂窝型催化剂是一种新型载体催化剂。它流体阻力小,几何外表面大,特别适宜于空间速度高、处于传质控制的过程。但是有关蜂窝型催化剂流体阻力的测定和计算的报导很少。有的计算方法,对不同结构和不同排     

二维蜂窝多孔金属夹层圆柱壳的传热性能数值模拟研究

文章以脉冲爆震发动机的爆震燃烧室为原型,分析二维蜂窝多孔金属夹层圆柱壳的传热问题.文中将二维蜂窝孔在管壁径向按放射状布置,将内表面设置成高温边界条件来模拟实际燃烧室工作情况,空气从蜂窝孔一侧流经材料与圆柱壳内表面充分换热后流出起到冷却作用;通过数值模拟分析了六边形孔、矩形孔和三角形孔按照不同的连结排布在夹层圆管中的传热性能与相对密度的关系;同时还研究了夹层层数对传热性能的影响.结果表明六边形孔排布的传热性能要优于其它拓扑构型;传热性能随单胞层数增加而增大,当层数达到一定值后,传热性能基本上保持不变.     

负载型V_2O_5-WO_3/TiO_2/堇青石脱硝催化剂的研制及性能

以TiO2/堇青石蜂窝陶瓷为载体,V2O5-WO3为活性组分,采用静态浸渍的方法制备了用于氨法选择性催化还原烟气中NO的SCR催化剂,通过XRD和BET对催化剂进行了表征,并考察了该催化剂的应用性能。考察了制备方法、温度、NO浓度、空速和NH3/NO对SCR反应的影响。结果表明,活性组分浸渍溶液中添加助溶剂对制备的催化剂活性有一定的影响,主要影响催化剂表面V2O5的聚集形态,导致脱硝活性下降;活性组分浸渍溶液中添加助溶剂时,可显著提高催化剂的脱硝活性,在反应温度为375℃、NH3/NO=1、空速为10 000h-1的条件下,所制备的催化剂的NO脱除率最高,可达99%。     

金属蜂窝结构有效热导率的预报与实验研究

建立了蜂窝夹芯结构有效热导率的数值计算模型,算例表明预报结果与实际值吻合很好.设计并制造了有效热导率的测试设备,对A l蜂窝样件进行了稳态热传导实验测试,结果表明,在平均温度高于150℃时与数值结果的相对误差不超过7%,所建立的分析和实验方法能够实现对蜂窝结构热性能的评价分析.     

相转移法合成UV-214

间苯二酚水溶液与三氯甲苯反应可制备紫外线吸收剂UV—214。通过向反应体系加入少量可溶性溶剂可以改善产品质量,考察了不同溶剂的用量对合成UV—214的影响,溶剂包括甲醇、DMF、二甲基亚砜和冰醋酸,实验结果表明,冰醋酸的效果较好。同时还考察了不同的阳离子表面活性剂、阴离子表面活性剂、聚乙二醇系列和乳化剂用量对合成UV—214的影响。实验结果发现十六烷基三甲基溴化铵的用量为0.4g时,UV-214的纯度可达99.4％,产品的分离产率为95.7％,外观为淡黄色,无需精制就可以作为紫外线吸收剂使用或合成其它二苯甲酮类紫外线吸收剂的原料,因此十六烷基三甲基溴化铵是比较理想的相转移剂。     

金属蜂窝夹芯板辐射导热耦合问题

针对金属蜂窝夹芯板,研究了其在气动加热条件下的非稳态传热行为.基于高温传热学原理,通过传热机制分析,建立了蜂窝夹芯板的导热-辐射一维瞬态耦合传热数学物理模型.在此基础上,采用控制容积法,结合蒙特卡罗法,发展形成了求解该类辐射导热耦合传热问题的数值方法,并给出了蜂窝夹芯板当量热导率和典型边界条件下金属蜂窝夹芯板瞬态温度场、非加热面热响应的计算方法,进行了典型算例计算和实验验证.结果表明,所建立的数值计算模型在预报蜂窝结构热响应方面是有效的,而且较之Swann-Pittman半经验关系式,提高了计算精度.     

高活性吸附剂的制备及性能研究

以粉煤灰/氧化钙为原料,制备高活性吸附剂,分析了水固比、水合时间、水合温度、添加剂对生成的吸附剂性能的影响.通过测试各试验条件下制备的吸附剂比表面积,表明水和反应制备的吸附剂最佳水固比为20、最优水和反应时间为10～15h,随着温度的升高或在水和过程中增加适量的添加剂,制备的吸附剂比表面积增大,有利于改善吸附剂的吸附性能.     

New advances in fiber-reinforced composite honeycomb materials

In sandwich structures, lightweight cellular materials as the core hold the face sheets far away from the neutral axis to maximize the bending performance of the structure. Honeycomb materials as a major type of lightweight cellular materials have been widely applied in various fields, including aerospace, vehicle, marine, architecture and mechanical engineering, due to reliable mechanical properties and excellent designability. Using fiber-reinforced composites is an efficient method to develop ultralight honeycomb materials with superior mechanical behaviors. In recent years, fiber-reinforced composite honeycomb materials possessing lightweight and excellent mechanical performances have attracted noticeable attention to replacing traditional aluminum honeycombs and Nomex honeycombs. Compared to metal, polymer and Nomex paper, fiber-reinforced composites possess various merits, such as high specific stiffness and specific strength, excellent fatigue property, corrosion resistance and high-temperature resistance. Thus, the applications of fiber-reinforced honeycomb material for sandwich core have unlimited potential in hypersonic vehicles, long-range rockets, cargo vessels and protective systems. Although the fact that attention has been rapidly increasing, there is a lack of comprehensive reviews of new advances in the field of fiber-reinforced composite honeycomb materials. In this review, new advances reported by different scientists in the field of fiber-reinforced honeycomb materials have been reviewed and analyzed to provide an in-depth overview and knowledge for beginners in the field of ultralightweight and high-performance composite sandwich architectures. The challenges and prospects for the development of fiberreinforced honeycomb materials have also been presented.     

催化臭氧化降解水中硝基苯的机制

为揭示蜂窝陶瓷催化臭氧化降解水中硝基苯的反应机理,从臭氧与非均相表面的作用方式上推测催化氧化过程中HO.的引发历程.采用XRD、FT-IR和SEM等手段对催化剂进行表征,结果表明,催化剂主晶相为2MgO.2Al2O3.5SiO2,是标准的α-堇青石;催化剂表面存在表面羟基,其含量为9.13×10-6mol/m2,催化剂表面的pHzpc=6.60,本实验条件下(pH=6.87),表面羟基是以游离羟基或氧负离子形式存在.催化剂含有碱性氧化物MgO及酸性氧化物Al2O3和SiO2,其表面存在金属离子Lewis酸位和表面羟基.当催化剂在水溶液中进行催化臭氧化反应时,Lewis酸优先与水配位而使水离解形成表面羟基,而臭氧与金属离子Lewis酸配位作用就会大大降低.臭氧会进一步与表面羟基形成配位键和氢键,而后经由—HO2-、O3·-和HO3·等活性物质生成HO·.     

TiO_2 preparation by improved homogeneous precipitation and application in SCR catalyst

Ultrasonic treatment and hydrothermal method were applied in the traditional homogeneous precipitation for nano-TiO_2 preparation, which was used as carrier material for the production of honeycomb selective catalytic reduction(SCR) catalyst. The influence rules of the two improved methods on characterization of TiO_2 samples, denitration activity and mechanical strength of honeycomb SCR catalyst samples were mainly focused on. The results indicate that the specific surface area, particle size and uniformity of TiO_2 samples are significantly improved by both of the ultrasonic and hydrothermal treatments compared with the traditional homogeneous precipitation. Also, the denitration activities of catalyst samples are enhanced by the two improved methods(the NO_x reduction ratio increases from 88.89% to 95.45% by ultrasonic homogeneous precipitation process, and to 94.12% by hydrothermal homogeneous precipitation process). On the other hand, because of good spherical shape and high particle distribution of TiO_2 sample from hydrothermal homogeneous precipitation process, the corresponding honeycomb catalyst samples get the best mechanical strength, which is even higher than that of the reference sample from commercial nano-TiO_2. So, it is concluded that the hydrothermal homogeneous precipitation can be a feasible and effective preparation method of TiO_2 carrier for the honeycomb SCR catalyst production.     

纸基蜂窝零件夹持方法研究

为了解决当前纸基蜂窝零件高速铣削加工夹持方法的可靠性和稳定性较差以及加工精度低的缺点,提出一种基于磁场和摩擦吸附原理的夹持方法.该方法利用灌入蜂窝芯中铁粉的自重以及外加磁场对铁粉的吸引力,在铁粉与蜂窝侧壁之间以及蜂窝芯与夹具平台之间产生可以控制的摩擦力,利用摩擦力的作用达到在高速加工过程中对纸基蜂窝芯零件的夹持.通过实验证明,该方法简单易行,适合于大批量生产.     

吸水性模板影响混凝土抗裂性能的试验研究

近年来,随着高性能混凝土和高强混凝土的应用,混凝土的水灰比不断降低,从而致使混凝土的干燥收缩变形和早期自收缩变形不断增大,在内外约束作用条件下就会在混凝土内产生很大的拉应力,而混凝土抗拉强度很低,特别是早期强度更低,当拉应力达到混凝土的抗拉强度时,就会使混凝土发生开裂,因此,混凝土的裂缝问题愈加严重,越来越引起工程建设人员的关注.通过表面粘贴吸水性模板抗裂试验,分析了吸水性模板对混凝土表面硬度、外观质量、强度和抗裂能力的影响,研究了吸水性模板对混凝土裂缝的控制机理,提出了粘贴吸水性模板控制混凝土表面裂缝的方法,可以从外在因素上提高混凝土的抗裂能力.     

Preparation and Characterization of Super Absorbent Resin from Natural Cellulose

The grafting polyacrylamide onto wood pulp cellulose (cell-g-PAM) was performed with cerous ammo-nium nitrate as the initiator and hydrolyzed to produce the super absorbent resin. The FTIR shows that the poly-acrylamide is grafted on the cellulose. After hydrolyzation, part of acrylamino groups are transformed into car-boxyl groups. The XRD analysis shows that the graft polymerization occurred at the amorphous section and the surface of the crystal section of cellulose. The SEM graph reveals that there is a layer of polymer on the surface of cellulose fiber and the fibril structure of the cellulose surface is covered. After hydrolyzation, the surface of the product is different from that of cell-g-PAM‘s and the surface is scraggy. The technical conditions to prepare high water absorbent resin were confirmed. Through the radical graft copolymerization, the high water absorbent resin can be produced from wood pulp cellulose.     

Thermal performance of solar air collector with transparent honeycomb made of glass tube

Transparent honeycomb structure with thin-walled glass tube as the honeycomb unit is designed and applied to a flat-plate solar air collector. Experiments are performed for solar collectors with six different honeycomb sizes. The emphasis is to study the effects of diameter and aspect ratio of the honeycomb unit on the transmittance and efficiency of the solar collector. It is shown that for the same diameter but different aspect ratios, there are large temperature differences between the collector’s exits;...     

吸附变压器中的酸性组分新法初探

以粉煤灰为原料经过适当的物理化处理,制成改性粉煤灰,进上步增加其表面积,可作为一种新型高效吸附剂,用于吸附变压器油中酸性组分,取得了较理想的结果。