Evaluation of Compatibilizers for Improving Compatibility between Waste Vegetable Oil and Aged Asphalt

Modifying agents 2,2-Bis(4-glycidyloxyphenyl)propane(2BPE)and dibutyl phthalate(DBP)were selected to enhance the compatibility.By using molecular simulation software(Materials Studio,MS),nine systems were constructed,including molecular models of aged asphalt and WVO monomers with 2BPE and/or DBP.The solubility parameters,Flory-Huggins parameters,and interaction energies of these systems were calculated to determine the impact of 2BPE and DBP on the compatibility of WVO and aged asphalt.Results showed that the addition of 2BPE and DBP reduced the difference in the solubility parameters between WVO and aged asphalt,thus improving the compatibility between WVO and aged asphalt.Additionally,using a combination of 2BPE and DBP in both aged asphalt and rejuvenator was found to be more effective than using either 2BPE or DBP alone.Finally,it was determined that evaluating the compatibility of WVO and aged asphalt using Van der Waals potential and non-bonding energy as evaluation indicators was more accurate than using electrostatic potential energy.

OPTIMIZATION OF ACOUSTIC IMPEDANCE，GEOMETRIC STRUCTURE AND OPERATING CONDITION OF LINERS MOUNTED IN ENGINE DUCT

Acoustically absorptive treatment in aircraft engine nacelle is an essential part of the overall aircraft noise reduction effort. The investigation on the optimization of multi-liners plays an important role in noise reduction. Based upon the mode analysis method of sound propagation in a circular duct with multiple liners, a flexible tolerance method is used to optimize the acoustic parameters(impedance), geometric structure parameters(such as open area ratio, cavity depth and hole diameter) and operating condition parameters(such as blade passing frequency). The mathematical models for these kinds of optimization are presented here. The optimum values of the design variables are determined when the in-duct sound suppression approaches a maximum. It can be derived from the optimum results that the emphasis of the engineering optimization design of the perforated plate honey-comb structure should be placed on the optimum choice of the open area ratio and cavity depth. Some reference criteria for the engineering design of the multi-linings are also provided.

Progress of Expert Systems in Electromagnetic Engineering

It is urgent to solve various problems in electromagnetic （EM） engineering under the increasingly complicated environment. Some expert systems （ES） come into being just to keep up with the demand for solving these problems. Combined with the analysis of development orES technology and the development trend of EM engineering software in recent years, the application orES technology in EM engineering is discussed, and especially the progress of complete ES in electromagnetic compatible （EMC） is introduced.

Analysis and Calibration of Internal Flow Force of EjectorPowered Engine Simulator System in Wind Tunnels

The ejector-powered engine simulator(EPES)system is an important piece of equipment in conducting an influence test of the intake and jet flow in low-speed wind tunnels.In this work,through the analysis of the structure and principle of EPES,three parts of the internal flow force were obtained,namely,the additional resistance before the inlet,the internal flow force in the inlet and the thrust produced by the ejector.On the assumption of one-dimensional isentropic adiabatic flow,the theoretical formulae for calculating the forces were derived according to the measured total pressure,static pressure and total temperature of the internal flow section.Subsequently,a calibration tank was used to calibrate the EPES system.On the basis of the characteristics of the EPES system,the process and method of its calibration were designed in detail,and the model installation interface of the calibration tank was reformed.By applying this method,the repeatability accuracy of the inlet flow rate calibration coefficient was less than0.05%,whereas that of the exhaust flow rate and velocity was less than 0.1%.Upon the application of the calibration coefficients to the correction of the wind tunnel experiment data,the results showed good agreement with the numerical simulation results in terms of regularity and magnitude before stall,which validates the reasonableness and feasibility of the calibration method.Analysis of the calibration data also demonstrated the consistency in the variation law and trend between the theoretical calculation and actual measurement of internal flow force,further reflecting the rationality and feasibility of the theoretical calculation.Nevertheless,the numerical difference was large and further widened with a higher ejection flow rate mainly because of the accuracy of flow measurement and the inhomogeneity of internal flow.The thrust deflection angle of EPES is an important factor in correcting this issue.In particular,the thrust deflection angle becomes larger with small ejection flow and becomes smaller with an increase in flow rate,essentially exhibiting a general change of less than 10°.

Performance Characteristics of Single Cylinder Diesel Engine under Different Operating Conditions

Recently, it is predicted that the fossil fuels will be sufficient for a few decades at the present extraction rates. So, the performance studies of the internal combustion engines play an important role to achieve the best operating point at different weather temperatures. In the present study, the effects of the inlet air temperatures on the engine performance characteristics were studied at different cooling loads. Several experiments were carried out on a single cylinder diesel engine （SCDI）. The performance characteristics of SCDI included： brake power, specific fuel consumption, brake thermal efficiency and exhaust emissions （carbon dioxide, CO2, carbon monoxide CO, and hydrocarbon HC）. The findings show that the inlet air temperature and cooling conditions have appreciable effect on the performance characteristics of the SCDI especially at low cooling rate. It can be concluded that the high cooling rate leads to the enhancement in the brake thermal efficiency, the b.s.f.c, and the emitted COz, CO, and HC. On the other hand the high cooling rate leads to the decrease in the volumetric efficiency. So, a compromising between the inlet air temperature and the cooling rate should be recommended for the engine best performance.

Free-Interface Dual-Compatibility Modal Synthesis Substructure Method in Large-Scale Structures

Free-interface dual-compatibility modal synthesis method(compatibility of both force and displacement on interfaces)is introduced to large-scale civil engineering structure to enhance computation efficiency. The basic equations of the method are first set up, and then the mode cut-off principle and the dividing principle are proposed. MATLAB is used for simulation in different frame structures. The simulation results demonstrate the applicability of this substructure method to civil engineering structures and the correctness of the proposed mode cut-off principle. Studies are also conducted on how to divide the whole structure for better computation efficiency while maintaining better precision. It is observed that the geometry and material properties should be considered, and the synthesis results would be more precise when the inflection points of the mode shapes are taken into consideration. Furthermore, the simulation performed on a large-scale high-rise connected structure further proves the feasibility and efficiency of this modal synthesis method compared with the traditional global method. It is also concluded from the simulation results that the fewer number of DOFs in each substructure will result in better computation efficiency, but too many substructures will be time-consuming due to the tedious synthesis procedures. Moreover, the substructures with free interface will introduce errors and reduce the precision dramatically, which should be avoided.

中药有效成分结合骨组织工程材料用于骨修复

背景:如何修复骨缺损一直以来是临床难题,中药有效成分在骨修复方面具有良好的生物活性与治疗效果,将中药有效成分与组织工程材料相结合在骨修复领域具有广阔的前景。不同中药有效成分与支架的组合在作用关系方面具有相似之处。目的:搜集常见的中药有效成分与支架材料组合的案例,基于七情配伍的启发将组织工程支架与中药有效成分类比为产生配伍关系的两类中药,以二者的作用关系为纲进行归纳总结。方法:检索1998年1月至2024年1月Pub Med和中国知网数据库中发表的相关文献,英文检索词:“traditional Chinese medicine,Chinese medicine,traditional Chinese medicine monomers,bone defect,bone repair,bone tissue engineering,tissue engineering,scaffold”,中文检索词:“中药,中药有效成分,中药单体,骨组织工程,骨组织工程支架,支架,组织工程,骨缺损,骨修复”,最终纳入88篇文献进行综述分析。结果与结论:(1)组织工程支架材料与中药有效成分各自均在骨修复领域有广泛的运用,二者在成骨方面优势明显但仍有许多缺陷,许多研究致力于将二者制备成复合材料,希望通过二者间的相互作用发挥减毒增效作用。(2)一些药物与材料在成骨、抗菌、促血管生成方面能互相促进,增强原有的效果,受到传统方剂配伍观念的启发,文章将其归纳为“相须”关系,并举实例佐证。(3)一些药物能提高材料的强度,而某些材料能对负载于其上的药物实现缓释控释效果、增加载药量与稳定性,或是进行靶向递送,文章将这种单方面的提升效果归纳为“相使”关系。(4)一些中药与材料搭配使用能减少对方的毒副反应,文章将这种减毒关系归纳为“相畏相杀”。(5)文章得出了一个由七情配伍关系启发、基于作用关系分类的关于中药复合支架的全新视角,将中药传统观念引入组织工程领域,为后续复合支架的研究者提供新的研究思路,并在选材搭配方面提供一定的便利。

Mechanical Behavior of Bistable Bump Surface for Morphing Inlet

There exists inlet-engine match conflict between high and low speeds for a non-adjustable bump inlet.A scheme of using a bistable bump surface at the throat region of the inlet is proposed to adjust the throat area.The FEM model of the bistable surface is established with hinged constraint,and the bistability condition and structural transition process are investigated in detail.Moreover,the effects of loading method,loading position and structural parameters on critical driving force,input energy and structural strain are studied.Finally,the influences of an elastic boundary condition on the structural bistability are discussed.The results show that the bistability of the adjustable bump surface requires a certain boundary constraint and geometric parameter combination,and that there are local and overall snap-through phenomena during transition which are related to the loading position and structural parameters.Therefore,suitable loading position and structural material could reduce input energy and meet the demand of structural strain.

变弯度导叶铰接位置对风扇振动特性的影响

针对变弯度导叶尾迹激励引起的转子叶片共振,基于谐响应模态叠加法对风扇转子进行强迫振动分析,研究了不同铰接位置的变弯度导叶对风扇气动性能及其振动特性的影响。结果表明,随着铰接位置向尾缘移动,风扇转子流量、压比和效率增加,稳定裕度降低,主要影响下游转子叶根部位的进气角度。在气动激励方面,随着铰接位置后移,转子叶片表面的压力幅值增大,相位变化剧烈,通过将非定常气动力转换到模态空间中,可以看到叶片所受模态气动力在铰接位置为35%C (C为轴向弦长)的情况下达到最大值,后呈现先减小后增加的规律,这与振动响应的变化规律一致。铰接位置对所关注的高阶局部模态的气动阻尼影响较小,最大差异为0.046%。在振动响应方面,转子叶片的振动应力随铰接位置剧烈改变,且为非单调变化。在设计位置处叶片的振动应力最小,在35%C处振动应力达到设计位置的15倍。对于本文所研究的模型及工况,最优铰接位置为45%C,与仅考虑气动性能的25%C不同。因此在变弯度导叶设计时,需要考虑其对叶片振动特性的影响。

泵入口参数对全流量补燃循环发动机动态特性影响研究

全流量补燃循环发动机性能高,并具备便于重复使用的优势,是未来重复使用运载器的最佳选择之一。在液体火箭发动机启动过程中,泵入口推进剂的压力和温度变化会对全流量补燃循环发动机动力系统的启动特性造成一定的影响。为分析其影响规律,建立了涡轮泵、预燃室、推力室、两相流和混合气体组件等动力学模型并进行求解。结果表明,随着燃料泵入口压力升高或氧化剂泵入口压力降低,涡轮泵系统参数的波动将会逐渐增大,甲烷温度和液氧温度所产生的影响要强于甲烷压力和液氧压力,而液氧的影响则强于甲烷。为动力系统中泵入口推进剂状态参数控制提供了一定的指导。

静电纺丝聚偏氟乙烯压电仿生骨膜的细胞相容性

背景:聚偏氟乙烯具有压电性能、良好的生物相容性和无毒性,使其成为骨膜修复合适的候选材料。目的:评价掺锌镁离子静电纺丝聚偏氟乙烯压电仿生骨膜的体外细胞毒性。方法:采用静电纺丝技术分别制备纯聚偏氟乙烯、掺锌离子聚偏氟乙烯、掺镁离子聚偏氟乙烯、掺锌镁离子聚偏氟乙烯压电仿生骨膜,依次命名为PVDF、PVDF-Zn、PVDF-Mg和PVDF-Zn-Mg,其中锌、镁离子的质量分数均为1%。将成骨细胞、血管内皮细胞分别与4组仿生骨膜共培养,通过碱性磷酸酶染色、CD31免疫荧光染色、扫描电镜观察与CCK-8法检测仿生骨膜的细胞相容性。结果与结论:①成骨细胞:培养7 d的碱性磷酸酶染色显示,PVDF-Zn组碱性磷酸酶分泌多于其他3组。扫描电镜下可见,培养1 d时,细胞在PVDF-Mg和PVDF-Zn-Mg仿生骨膜表面得到了一定的铺展,伪足向四周伸展;到3 d时,各组细胞边缘向材料伸出伪足;到第5,7天时,细胞铺展充分、生长形态良好且牢牢地覆盖在纤维表面,细胞伪足向四周及纤维空隙中伸展。CCK-8检测显示,随着时间的推移,各组仿生骨膜上的细胞增殖呈上升趋势,培养1,3,5,7 d的细胞相对增殖率均≥75%,细胞毒性≤1级。②血管内皮细胞:培养3 d的CD31免疫荧光染色显示,细胞在各组仿生骨膜上良好地黏附和铺展,彼此连接,其中PVDF-Zn-Mg组细胞数量多于其他3组。扫描电镜下可见,培养1,3 d时,细胞开始黏附在各组纤维表面;到5 d时,细胞在纤维表面均铺展良好并伸出明显的伪足;到7 d时,PVDF-Mg、PVDF-Zn-Mg仿生骨膜上的细胞呈复层生长,并伸展伪足至纤维空隙内。CCK-8检测显示,随着时间推移,各组仿生骨膜上的细胞增殖呈下降趋势,培养1,3,5,7 d的细胞相对增殖率均≥125%,细胞毒性为0级。③结果表明:掺锌镁离子静电纺丝聚偏氟乙烯压电仿生骨膜具有良好的细胞相容性。

二元超声速混压式进气道亚临界稳定裕度研究

为了研究内收缩比和来流马赫数对二元超声速混压式进气道亚临界稳定裕度的影响规律及失稳机制,采用二维非定常仿真方法研究了内收缩比(ICR)为1.04~1.25的进气道在来流马赫数Ma0为2.4的条件下,以及内收缩比为1.08的进气道在来流马赫数为2.2~2.8条件下,其由稳态向失稳状态转变的过程。研究结果表明:(1)当Ma0=2.4时,在1.04≤ICR≤1.12内,随着ICR增加,亚临界稳定裕度ζ减小;1.16≤ICR≤1.25内,随着ICR增加,亚临界稳定裕度增大。(2)在内收缩比为1.08的条件下,马赫数变化引起的分离激波角和分离包再附压升两个关键因素变化共同主宰着进气道亚临界稳定裕度的变化趋势。(3)总体上,根据稳定亚临界初始状态的三相点无量纲高度?b是否大于1可将进气道的亚临界稳定裕度变化情形分为两类,当?b<1时,ζ随着?b的增加而减小;当?b> 1时,ζ随着?b的增加而增加。

摩托车散热器护罩结构对其进风量的影响分析

为保护散热器不被泥土污染,需在散热器进风端添加散热器护罩。散热器护罩添加后对散热器进风量有明显的影响。为获取较优的散热器护罩结构设计,采用CFD分析方法搭建摩托车整车外流场计算域模型,结合不同散热器护罩结构方案,分析散热器护罩结构对其进风量的影响,选取合适的散热器护罩方案开展整车实验验证。结果表明:散热器护罩上导流板角度130°且散热器护罩与芯体间的间隙为1 mm时,散热器进风量为281.7 g/s,与无护罩状态的进风量相当。护罩与芯体间存在间隙可提升散热器进风量,建议间隙控制在1~2.5 mm;散热器护罩网孔倾斜和导流板开孔不利于风量提升。经对比测试,怠速工况、最高车速工况及最大扭矩工况下,散热器添加护罩后的发动机出水温度与无护罩状态的发动机出水温度基本一致。适当减小风扇罩挡风面积可进一步提升散热器进风量,散热器添加护罩后,人体大腿两侧不会出现明显热风。研究结果可为摩托车散热器护罩结构设计及优化提供理论参考。

多聚磷酸对不同基质沥青性能的影响研究

在沥青路面的长期服役过程中,车辆荷载、气候侵蚀和环境劣化作用会造成沥青性能的降低,进而导致路面病害的产生。为提高沥青路面性能,改性沥青被广泛应用于道路建设中。针对传统聚合物改性沥青价格高、储存稳定性差,采用多聚磷酸(PPA)对沥青进行改性。相较于传统聚合物改性沥青,PPA改性沥青具有储存稳定性好、价格便宜及高温性能好等优点,但其对于不同基质沥青改性效果的差异较大,因此遴选6种国内常用基质沥青,通过软化点、延度及针入度试验、弯曲梁蠕变试验、动态剪切流变试验及Pull-off试验,研究了不同PPA改性沥青高低温性能及黏附性能。结果表明:PPA的掺入可显著提高沥青的软化点,随着PPA掺量的增加,沥青的延度及针入度逐渐降低,―18℃下劲度模量显著提高,表明PPA对沥青的低温性能存在显著的负面影响。温度扫描试验结果表明:PPA对不同基质沥青流变特性的影响有着较大的差异,PPA+70#沥青的流变性能总体高于PPA+90#沥青,但其温度敏感性较大。Pull-off试验表明:PPA的加入可显著提高沥青的拉拔强度,表明PPA改性沥青有着优异的黏附性能。红外光谱试验结果表明:PPA与不同基质沥青间的反应有着较大的差异。

Experimental Investigation of Nozzle Effects on Thrust and Inlet Pressure of an Air-breathing Pulse Detonation Engine

Nozzle effects on thrust and inlet pressure of a multi-cycle air-breathing pulse detonation engine （APDE） are investigated experimentally. An APDE with 68 mm in diameter and 2 050 mm in length is operated using gasoline/air mixture. Straight nozzle, converging nozzle, converging-diverging nozzle and diverging nozzle are tested. The results show that thrust augmentation of converging-diverging nozzle, diverging nozzle or straight nozzle is better than that of converging nozzle on the whole. Thrust augmentation of straight nozzle is worse than those of converging-diverging nozzle and diverging nozzle. Thrust augmentations of diverging nozzle with larger expansion ratio and converging-diverging nozzle with larger throat area range from 20% to 40% on tested frequencies and are better than those of congeneric other nozzles respectively. Nozzle effects on inlet pressure are also researched. At each frequency it is indicated that filling pressures and average peak pressures of inlet with diverging nozzle and converging-diverging nozzle with large throat cross section area are higher than those with straight nozzle and converging nozzle Pressures near thrust wall increase in an increase order from without nozzle, with diverging nozzle, straight nozzle and converging-diverging nozzle to converging nozzle.

基于樽海鞘群极限学习机的进/发一体化性能寻优控制模型研究

为充分发挥航空推进系统的性能,提高性能寻优控制的实时性,将樽海鞘群算法(SSA)与极限学习机(ELM)相结合,基于进/发一体化部件级模型建立数据集,提出一种基于SSA-ELM的数据驱动模型。将该建模方法与广义回归神经网络(GRNN)、BP神经网络(BPNN)和极限学习机(ELM)比较,结果表明,相比于BPNN,ELM,GRNN,SSA-ELM用于预测可以使安装推力的均方根误差(RMSE)分别降低7.41%,17.01%,72.57%,安装油耗的RMSE分别降低4.32%,19.41%,66.77%,具有更高的预测精度。将基于SSA-ELM的数据驱动模型作为机载模型应用到性能寻优控制,结果表明,该机载模型能够维持理想的寻优效果。针对最大安装推力模式开展实时性分析,该机载模型相比于进/发一体化部件级模型,平均计算时间由184.05 ms缩短至1.357 ms,实时性得到显著改善,大大提高了寻优效率。

基于Zukauskas关系式的预冷发动机进气道流动特性研究

为了研究预冷发动机进气道流动特性,以二维变几何轴对称进气道为研究对象,利用Zukauskas横掠管束绕流关系式,对进气道流场展开了数值仿真研究,探究预冷器的冷却效应及换热管直径对进气道流场、性能的影响。结果表明:Zukauskas关系式能较好地预测气流在预冷器管束间的流动损失;经过预冷后,涡轮通道总温大幅下降,但总温分布不均匀,温度梯度明显,对流换热对上游流体总温产生的影响很小;在Ma_(∞)=2~5飞行工况下,换热功率随着飞行马赫数的增加而增大,涡轮通道的出口总温较预冷前降低了22%~60%,出口马赫数降低了17%~51%,反压比增加了10%~26%,总压恢复系数增加了3%~8%;当预冷器的管径从1 mm增大至2.5 mm时,涡轮通道出口速度降低了16.5%,反压比降低了1%,总压恢复系数呈现先下降后上升的趋势。将虚拟预冷器管束排布方式改为顺排,预冷器的换热功率下降,出口总温上升,涡轮通道的出口速度上升了11%~30%。

基于Actran软件的进气道二维模型声学仿真

针对经典JT15D航空发动机模型,利用Actran软件中的Actran/TM模块和Actran/DMG模块分别对该发动机进气道声传播特性进行仿真计算。仿真基于二维模型展开,通过TM模块研究了不同网格类型、网格尺寸等参数对仿真结果的影响。此外,建立了基于Actran/DMG模块的二维模型仿真,并与Actran/TM模块二维仿真数据进行了对比研究,以确立该软件中2种仿真模块在航空发动机进气道声传播仿真方面的特点。

燃料电池发动机电磁兼容设计技术研究

随着新能源行业的迅速发展,燃料电池发动机作为未来新能源系统的动力核心,越来越受到重视,而相较于传统的燃油、燃气发动机,燃料电池发动机在能源的来源及尾气排放等方面都具有明显的优势,但是由于燃料电池发动机匹配有高压、大功率的电气设备,如:DC/DC变换器、鼓风机、循环泵等,在运行的过程中极易产生严重的电磁干扰,严重影响整机的运行及可靠性,因此从电磁兼容的的原理及影响因素等方面进行了分析,提出了解决此类干扰的一些措施,并结合相关故障案例,进行了分析,希望对电磁兼容问题解决提供帮助。

发动机进气总温的无监督修正算法

在发动机进气总温测量过程中,受气流速度、辐射、对流、传导等因素影响,测量值常常偏离实际值。国内目前已有机构通过吹风设备获取总温恢复系数以修正气流速度引起的误差,但这种方法只是对气流速度误差进行修正,而未考虑自加热误差、防冰误差、热对流误差、热辐射误差、热传导误差等对进气总温的影响,获取的修正结果具有局限性。提出一种基于模型的总温修正方法,通过无监督的方法搜索到总温标签值并基于专家经验进行修正,再通过对历史数据的训练建立模型,以提高修正的性能。在特定进气条件和受感部下,该方法能够更全面地考虑各类误差因素,从而提供更准确的进气总温修正结果。