自行车涂层耐候性检测方法探析

结合自行车涂层特点,采用自然曝晒、荧光灯人工气候老化UVA和UVB 3种检测方法检测涂层耐候性,通过分析检测方法和检测结果的差异,选择便宜、快捷、直观的UVB作为自行车涂层的耐候性检测方法。     

火工品电阻测量仪器的发展趋势

火工品电阻测量仪器主要是对电雷管、点火具，接插件等电火工品的低电阻进行测量。由于安全性要求极高，测试电流被严格限制在一个较小值，这就对仪器精度的提高带来诸多问题。分析了制约仪器精度提高的主要因素、提出了解决方案，探讨了该种仪器的发展趋势。     

离心机均匀布料洗涤装置的研制

详细介绍一种新型离心机用布料洗涤装置的结构和工作原理,指出利用该布料洗涤装置,可以有效解决传统布料装置引起的布料不均、布料振动以及洗涤液浪费等问题;并列举了该装置布料洗涤时影响布料和洗涤效果的各种因素;举例说明该装置在无基础立式刮刀离心机上的应用;指出应用该装置改造传统离心机需要注意的事项。     

Adaptive digital calibration techniques for narrow band low-IF receivers with on-chip PLL

Digital calibration and control techniques for narrow band integrated low-IF receivers with on-chip frequency synthesizer are presented. The calibration and control system, which is adopted to ensure an achievable signal-to-noise ratio and bit error rate, consists of a digitally controlled, high resolution dB-linear automatic gain control (AGC), an inphase (I) and quadrature (Q) gain and phase mismatch calibration, and an automatic frequency calibration (AFC) of a wideband voltage-controlled oscillator in a PLL based frequency synthesizer. The calibration system has a low design complexity with little power and small die area. Simulation results show that the calibration system can enlarge the dynamic range to 72 dB and minimize the phase and amplitude imbalance between I and Q to 0.08° and 0.024 dB, respectively, which means the image rejection ratio is better than 60 dB. In addition, the calibration time of the AFC is 1.12μs only with a reference clock of 100 MHz.     

基于Pro/E二次开发的注射机双曲肘合模机构的参数化设计

利用机构学的方法对双曲肘合模机构进行了运动分析,并确立了合模行程、各肘杆尺寸及最大启模角等参数间的关联关系。通过使用Pro/E二次开发技术,讨论了应用Pro/toolkit进行菜单开发及零件参数化实现的方法;以MFC对话框设计技术和VC++建立了双曲肘合模机构参数驱动自动生成技术,开发出了与Pro/E 4.0系统集成的合模机构零件参数化设计系统。     

Simple molecular structure design of iridium(III) complexes: Achieving highly efficient non-doped devices with low efficiency roll-off

To construct efficient emitters suitable for non-doped devices and deeply understand the relationship between structures and performances, we designed and synthesized two heteroleptic iridium(III) complexes based on 1,2-diphenyl-1H-benzoimidazole (PBI) ligands whose substituents are varied simply from methyl (complex 2) to tert-butyl groups (complex 3). The parent complex 1 with non-substituent on PBI ligand has also been presented for a better comparison. Their photophysical, electrochemical and electroluminescent (EL) performances are investigated systematically. Despite their structural modification, all complexes exhibit almost identical emission and excited-state characters, which are rationalized by the quantum-chemical calculations. However, the obvious differences on device performances are found. Non-doped device employing 3 as emitting layer displays the highest EL performance with maximum current efficiency (η_{c, max}) of 18.6 cd A⁻¹ and power efficiency (η_{p, max}) of 16.2 lm W⁻¹ accompanied by low efficiency roll-off values, which is much higher than those of complexes 1 and 2. The obtained results herein suggest that introduction of the simple substituent into PBI ligand is an effective and feasible approach to develop highly efficient non-doped phosphors.     

Poly(DL-lactide-co-ε-caprolactone) and poly(DL-lactide-co-glycolide) blends for biomedical application: Physical properties,cell compatibility,and in vitro degradation behavior

Poly(DL-lactide-co-ε-caprolactone) (PLCL) and poly(DL-lactide-co-glycolide) (PLGA) blends of various compositions were prepared. Fractured sections of PLCL/PLGA blends did not evidence phase separation and blend glass transition temperatures suggested some degree of blend compatibility. The elastic modulus showed a negative deviation from the additive law of mixture. Superior biocompatibility in terms of fibroblast NIH 3T3 cell adhesion and proliferation, better mechanical properties, and a more homogeneous phase were obtained with PLCL/PLGA 25/75 blend. Rapid degradation of PLCL phase (4–8 weeks) in PLCL/PLGA 25/75 blend led to a porous structure, which makes it a potential candidate for drug delivery systems.     

Macro-level pedestrian and bicycle crash analysis: Incorporating spatial spillover effects in dual state count models

This study attempts to explore the viability of dual-state models (i.e., zero-inflated and hurdle models) for traffic analysis zones (TAZs) based pedestrian and bicycle crash frequency analysis. Additionally, spatial spillover effects are explored in the models by employing exogenous variables from neighboring zones. The dual-state models such as zero-inflated negative binomial and hurdle negative binomial models (with and without spatial effects) are compared with the conventional single-state model (i.e., negative binomial). The model comparison for pedestrian and bicycle crashes revealed that the models that considered observed spatial effects perform better than the models that did not consider the observed spatial effects. Across the models with spatial spillover effects, the dual-state models especially zero-inflated negative binomial model offered better performance compared to single-state models. Moreover, the model results clearly highlighted the importance of various traffic, roadway, and sociodemographic characteristics of the TAZ as well as neighboring TAZs on pedestrian and bicycle crash frequency.     

Highly-reproducible nonvolatile memristive devices based on polyvinylpyrrolidone: Graphene quantum-dot nanocomposites

The properties of nonvolatile memristive devices (NMD) fabricated utilizing organic/inorganic hybrid nanocomposites were investigated due to their superior advantages such as mechanical flexibility, low cost, low-power consumption, simple technological process in fabrication and high reproducibility. The current-voltage (I-V) curves for the Al/polyvinylpyrrolidone (PVP): graphene quantum-dot (GQD)/indium-tin-oxide (ITO) memristive devices showed current bistability characteristics at 300 K. The window margins corresponding to the high-conductivity (ON) state and the low-conductivity (OFF) state of the devices increased with increasing concentration of the GQDs. The ON/OFF ratio of the optimized device was 1 × 10⁴, which was the largest memory margin among the devices fabricated in this research. The endurance number of ON/OFF switching was above 1 × 10² cycles, and the retention time was relatively constant, maintaining a value above 10⁴ s. The devices showed high reproducibility with the writing voltage being distributed between −0.5 and −1.5 V and the erasing voltage being distributed between 2 and 3 V. The ON state currents remained between 0.02 and 0.03 A, and the OFF state currents stayed between 10⁻⁶ and 10⁻⁴ A. The carrier transport mechanisms are illustrated by using both the results obtained by fitting the I-V curves and the energy band diagrams of the devices.     

英国EE的LTE运营案例分析及启示

本文通过对英国移动运营商 Everything Ev-erywhere 公司（简称“EE”）的案例研究，从网络、终端、市场策略三个维度进行了问题分析，探寻该企业未能在较长的时间窗口内达到市场预期的原因，并在网络覆盖、终端提供、品牌推广、资费与市场定位、业务等方面总结了对中国移动 LTE 发展的启示。