A comprehensive study on the droplet formation processes and its influencing factors of a tubular piezoelectric print head

Abstract

Various inks with different properties are widely used in the printed electronic industry. In order to obtain high quality inkjet printing, it is necessary to study the droplet formation process and its influencing factors comprehensively. Only in this way, the incentive conditions and liquid physical parameters of droplet ejection can be obtained and optimized. Firstly, the calculation model of the droplet ejection process is established for a tubular print head and the boundary conditions are set according to the driving characteristics. Secondly, the free surface flow is calculated in the simulation software and sequential pictures of the droplet formation processes are captured to validate the availability of the numerical algorithm. Finally, the droplet formation processes of the tubular piezoelectric print head are simulated under different incentive conditions, different viscosities and different surface tensions. Too small a driving energy is insufficient to cause the head to eject droplets. Excessive excitation energy will result in larger or multiple satellite droplets. Additionally, the thinning process of the liquid neck is examined carefully in this paper. Results show that surface tension and viscosity have a significant effect on the thinning speed of the liquid neck, but the effect is not as significant as previous studies.     

基于Windows平行文件系统下的平行I/O

近年来,平行档案系统被广泛的用来解决这个问题,除此之外,由于电脑被使用于平行处理平台的普及率逐步上升,造成使用于电脑上的平行处理软体需求量持续增加,但是,却有可能缺乏平行I/O的系统。因此,文章旨在研究与分析Windows平行文件系统下的平行I/O的特点与实现方式。     

专用丁苯胶乳对混凝土的改性

用自制的专用丁苯胶乳对混凝土进行改性,考察了聚合物与混凝土质量比(简称聚灰比)、水与混凝土质量比(简称水灰比)、消泡剂用量、养护条件和胶乳稳定性对改性混凝土性能的影响。结果表明,当聚灰比为12%、水灰比为35%、消泡剂质量分数为丁苯胶乳的3%时,且在混凝土浇铸后干养28d的条件下,改性混凝土的抗压强度、抗折强度、黏结强度及抗渗性比未改性混凝土分别提高了6%,9%,85%,50%。稳定性越好的胶乳对改性混凝土的性能提高幅度越大。     

塔里木河“二源一干”生态供水潜力研究

为解决塔里木河干流水资源短缺、流域损失水量过大、用水效率低下、农业灌溉用水挤占生态用水等问题,基于“节水优先”的治水方针,以塔里木河二源流(阿克苏河、叶尔羌河)及其干流(“二源一干”)的山区水库群和平原水库群为研究对象,兼顾塔里木河干流的农业灌溉用水、生态用水、工业用水、生活用水等多目标,构建并求解了现状水平年和远景规划年的山区与平原水库群联合调度优化模型,分析了塔里木河干流的生态供水潜力和山区水库群联合调度的贡献。结果表明：仅通过干流平原水库群联合调度,农业灌溉用水和生态用水的供水保证率难以满足设计要求;通过山区与平原水库群优化调度,在远景规划年各行业均满足设计保证率要求,体现了山区水库群显著的调控性能和“节水优先”治水方针的合理性和可靠性;远景规划年塔里木河干流的生态供水潜力为2.84亿m³,可为塔里木河下游生态保护与修复提供了坚实的水量基础。     

A low‐profile antenna with circularly polarized reconfigurable and omnidirectional radiation patterns

A low profile circularly polarized (CP) antenna with reconfigurable polarization is designed and presented, which can radiate omnidirectional patterns that can be switched between left‐hand circularly polarized (LHCP) and right‐hand circularly polarized (RHCP). A pair of arc‐shaped complementary dipoles is acted as reconfigurable elements by bridging four pin diodes at the dipole arced arms. A meander phase shift line is employed to connected the arc dipole arms and plate cavity to adjust the phase relationship of two sources. The proposed antenna exhibits the omnidirectional radiation pattern by combining six identical elements placed in a circular array configuration. 24 p‐i‐n diodes are exploited to six elements, by manipulating the dc bias voltage across the diodes, the polarization state of the antenna can be switched. The patterns of the antenna are similar to that of a dipole, but its size is only about Φ0.87 × 0.029λ₀ at 5.8 GHz. The overlapped bandwidth of measured 3‐dB axial ratio (AR) and 10‐dB return loss is 5.724‐5.87 and 5.738‐5.91 GHz for two polarization states, which are right on the target of ISM band. It can be well adapted to medical diagnosis systems.     

Synthesis of HTPB based PU-PS IPN membrane for pervaporation recovery of butanol

Hydroxyl terminated polybutadiene(HTPB) based polyurethane(PU)-polystyrene(PS) interpenetrating polymer network(IPN) was prepared and characterized by FTIR, TGA, WCA, swelling experiments, and SEM. The IPN was used for pervaporation(PV) recovery of butanol. Both the permeation flux and separation factor increased with feed temperature, and both water and butanol fluxes increased with feed concentration while no obvious effect of concentration on separation factor was found. Through the formation of IPN structure, the total flux of HTPB based PU increased greatly with the decrease of separation factor. At the feed temperature of 60 °C, the IPN membrane obtained a total flux of 613.3 g/m~2 h with a separation factor of 6.15.     

天然气互换性多组分配气计算及软件开发

随着我国天然气行业的发展,城市天然气多气源供气现象将长期存在。在天然气互换性问题基础上,为满足互换性实验的要求,在实验室得不到供应各地方实际气源气的前提下,以北京地区为例,对各气源天然气进行多组分配气计算并编写相关软件,得到不同配气方案下各气源天然气的实验配制气。通过分析不同配气方案下配制气的燃烧特性参数,并结合天然气互换性实验系统的要求甄选出了最佳配气方案。     

Experimental characterization of the bipolar effect on P-hit single-event transients in 65 nm twin-well and triple-well CMOS technologies

Single-event charge collection is controlled by drift, diffusion and the bipolar effect. Previous work has established that the bipolar effect is significant in the p-type metal-oxide-semiconductor field-effect transistor (PMOS) in 90 nm technology and above. However, the consequences of the bipolar effect on P-hit single-event transients have still not completely been characterized in 65 nm technology. In this paper, characterization of the consequences of the bipolar effect on P-hit single-event transients is performed by heavy ion experiments in both 65 nm twin-well and triple-well complementary metal-oxide-semiconductor (CMOS) technologies. Two inverter chains with clever layout structures are explored for the characterization. Ge (linear energy transfer (LET) = 37.4 MeV cm²/mg) and Ti (LET = 22.2 MeV cm²/mg) particles are also employed. The experimental results show that with Ge (Ti) exposure, the average pulse reduction is 49 ps (45 ps) in triple-well CMOS technology and 42 ps (32 ps) in twin-well CMOS technology when the bipolar effect is efficiently mitigated. This characterization will provide an important reference for radiation hardening integrated circuit design.     

Spray-coated PDMS/PVDF composite membrane for enhanced butanol recovery by pervaporation

In this study, spray-coating was used to prepare dihydroxypolydimethylsiloxane (PDMS) composite membranes with high flux and separation factor for biobutanol recovery from aqueous solution. A thin, smooth, and defect-free PDMS layer was prepared by spray-coating on polyvinylidene difluoride ultrafiltration membrane with little PDMS penetration. The effects of process parameters for membrane fabrication and pervaporation on membrane performance were investigated. A membrane with 2 μm active layer was obtained with a high flux of 1306.9 g/m² h. The optimal membrane with the highest pervaporation separation index (PSI) (19.15 kg/m² h) showed a total flux of 530.6 g/m² h and a separation factor of 36.1 at 37°C, and a PSI of 65.61 kg/m² h and a flux of 1927.0 g/m² h at 70°C. Membrane performance was affected by feed composition and temperature. Acetone-butanol-ethanol solution and fermentation broth gave lower butanol fluxes and separation factors compared to butanol model solution.     

基于响应面法的双边长初级永磁直线同步电机多目标优化设计

永磁直线同步电机由于存在边端效应以及齿槽效应,在运行中不可避免地产生推力波动。针对高速大推力密度应用场景,对一种双边长初级PMLSM开展了优化设计。将有限元法与解析法结合,首先独立分析了轴向长度、极弧系数和初级轭部高度等单个参数对电机水平推力和推力波动的影响,并进一步采用Taguchi法筛选显著性较高的结构参数。在此基础上,以提高电磁推力、减小推力波动为优化目标对电机进行响应面分析,得到最终的电机尺寸优化参数。最后制作样机并搭建实验平台,验证了所提优化方法的有效性。