基于PCI-1711数据采集卡的拉力试验机实时控制系统

分析了液压拉力试验机系统组成和控制特性,使用VisualC++程序设计语言开发了拉力试验机计算机实时控制系统。通过PCI-1711高速数据采集卡实现信号的实时采集和输出控制,该控制系统能够严格控制系统的超调量,明显减小了液压组件载荷的波动与液压冲击,设备运行更平稳,提高了设备的使用寿命和控制精度。     

气阀对往复压缩机主要性能的影响分析

可靠性、容积流量、能耗是评价往复压缩机性能的重要指标,都与压缩机气阀有着密切关系。阐述了气阀影响往复压缩机可靠性、容积流量、能耗的主要因素或机理,对气阀的设计、制造、使用、维修等具有较大参考价值。     

Zr和Ce对Ti-11Si亚共晶合金组织及压缩性能的影响

采用显微组织观察(OM)、X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)以及压缩性能测试等手段,研究了元素Zr和Ce对Ti-11 at%Si铸态亚共晶合金组织和室温压缩性能的影响。结果表明,在Ti-Si亚共晶合金中添加8.0 at%的Zr可降低Si在α-Ti中的固溶度,促进硅化物细小、弥散析出,可改善合金的压缩强度和塑性。而添加0.5 at%的Ce可以明显细化α-Ti枝晶和共晶团组织,也可提高合金的压缩强度和塑性。且Ce对Ti-Si亚共晶合金的细晶强化效果比Zr要好。物相分析和EDS结果表明,Zr和Ce都主要存在于Ti5Si3相中,Zr则取代了部分Ti原子,形成了(Ti,Zr)5Si3相,Ce取代了部分Si原子,形成了三元硅化物Ti5(Si,Ce)3相。     

Liquidus Projection and Reaction Scheme of the Co-Al-Nb System

By metallographic observation of the as-cast microstructures, determination of the liquidus temperatures and the temperatures of invariant reactions by differential thermal analysis, and measurement of the compositions of the primary phases and the eutectic residuals by electron probe miroanalysis, a liquidus projection for the Co-Al-Nb system has been established for the first time. The binary Co-Nb intermetallic phases have a large solid solubility for Al and their melting temperatures increase markedly by the addition of Al. The only ternary compound, the Heusler phase NbCo₂Al, melts incongruently at about 1485?°C. By CALPHAD modelling the consistency of the experimental data has been checked. Calculated and experimentally determined temperatures of the invariant reactions are in good agreement and are summarised within a reaction scheme.     

固定化脂肪酶在离子液体中催化合成生物柴油

通过硅胶载体涂布法对细菌Burkholderia cepacia GX-35所产的脂肪酶进行固定化。比较了自制固定化脂肪酶在4种离子液体中催化合成生物柴油的效果,其中文章研究新设计并合成的一种离子液体溴代1-乙基-2-甲基咪唑[EMIM]Br对催化反应起促进作用。通过对转酯率的测定,研究了固定化脂肪酶在[EMIM]Br中的最适反应条件:最适反应温度为35℃,[EMIM]Br加入量为花生油质量分数的60%,最佳醇类为乙醇,加水量为花生油质量分数的5%,乙醇与花生油之比为9∶1,固定化脂肪酶加入量为花生油的20%,反应时间为6 h。固定化脂肪酶在[EMIM]Br中稳定性好,使用6次之后转酯率下降不明显。试验结果表明,与不加[EMIM]Br相比,加[EMIM]Br能有效提高生物柴油的转化率。     

降低小型柴油机排放的试验研究

从生物混合燃料成分、燃烧室结构和排气再循环等方面探索降低柴油机排放的方法。通过对柴油机排放性能的大量试验研究,结果表明:对于直喷式柴油机,生物混合燃料的NOx排放与柴油的排放基本相当,碳烟排放则比柴油有较大幅度的降低,而涡流室柴油机,NOx的排放量却有大幅度的降低,碳烟排放则比直喷式柴油机有更大幅度的降低,生物燃料的添加比例对NOx的排放影响不大。柴油机采用排气再循环技术后,混合燃料的碳烟排放仍比柴油少,混合燃料可以承载一定的EGR率而不增加碳烟排放。排气再循环可以大幅度地降低NOx排放且与EGR率有关,与燃料的性质关系不大。涡流室柴油机采用生物燃料和排气再循环,可以同时降低NOx和碳烟的排放,排放效果非常优良。     

甘薯吸附剂固定床吸附脱水制燃料乙醇及技术思考

在自行设计的固定吸附床上,研究了甘薯吸附剂对体积分数为95%的乙醇吸附脱水制燃料乙醇;重点考察了吸附过程中床层温度变化以及进床气速、床层高度、甘薯颗粒粒度等因素对透过曲线的影响,并结合床层温度变化给出了吸附波移动速度、传质区长度的计算方法,提出了甘薯固定吸附床对体积分数为95%的乙醇吸附脱水制燃料乙醇的工艺流程。     

响应面法优化海带酸水解预处理工艺

采用响应面法优化酸水解海带预处理的工艺条件。在对硫酸浓度、水解时间、底物浓度、水解温度4个因素进行单因素试验基础上,以还原糖得率为响应值,以Box-Behnken中心组合设计方法,建立预处理工艺参数的回归模型,利用软件Design-Expert 7.1.6作响应曲面分析,得出海带预处理理论最佳工艺参数;对理论参数进行了平行试验验证及校正,得到最优工艺参数:酸浓度为0.48 mol/L,底物浓度为8%,水解时间为43 min,水解温度为120℃,在此条件下还原糖得率为25.47%。通过验证可知,建立的数学模型能够较好地预测试验结果。     

Microstructure and mechanical properties of graphitic a-C:H:Si films

A series of graphitic a-C:H:Si films with different Si content were prepared by altering the sputtering current in a hybrid RF-PECVD and magnetron sputtering system. Microstructures and mechanical properties of them were characterized by IR, Raman, XPS, nanoindentation and scratch tests. Results show that although the sp³/sp² ratio increases with increasing Si content and as high as 8.2 at.% of silicon was doped, the a-C:H:Si films remain graphitic in nature and the I_D/I_G ratio is nearly constant for all. The coupling effects of sputtering-induced heating and strong ion bombarding due to negatively biasing were considered to be responsible for the film graphitization. The graphitic nature also accounts for the lower nanohardness of prepared a-C:H:Si films than the diamond-like a-C:H and a-C:H:Si films.     

Electrical properties of niobium doped barium bismuth-titanate ceramics

BaBi₄Ti_4–5/4xNb_xO₁₅ (BBNTx, x = 0, 0.05, 0.15, 0.30) ceramics have been prepared by solid state method. XRD data indicate the formation of single-phase-layered perovskites for all compositions. SEM micrographs suggest that the grain size decreases with Nb doping. The effect of niobium doping on the dielectric and relaxor behavior of BaBi₄Ti₄O₁₅ ceramics was investigated in a wide range of temperatures (20–777 °C) and frequencies (1.21 kHz to 1 MHz). Nb doping influences T_c decrease as well as the decrease of dielectric permittivity at Curie temperature. At room temperature, undoped BaBi₄Ti₄O₁₅ exhibits dielectric constant of ～204 at 100 kHz, that slightly increases with Nb doping. The conductivity of BBNT5 ceramics is found to be lower than that of other investigated compositions. The value of activation energy of σ_DC was found to be 0.89 eV, 1.01 eV, 0.93 eV and 0.71 eV for BBT, BBNT5, BBNT15 and BBNT30, respectively.