艾叶精油化学成分研究

本文用水蒸气蒸馏法提取了不同产地艾叶精油,采用GC-MS技术分析了艾叶精油的化学成分。结果不同产地艾叶精油的质量收率为0.29%～0.56%,都含有特征成分:α-蒎烯、β-蒎烯、α-松油烯、γ-松油烯、桉叶素、蒿酮、蒿醇、2-环己烯-1-醇、樟脑、龙脑、4-松油醇、反式-石竹烯、丁子香酚。其中具有药效作用的成分有桉叶素(14.32%～26.12%,质量百分数,下同),樟脑(3.66%～14.97%)、龙脑(0.51%～10.53%)、甘菊环(0.00%～23.95%)等,有毒成分侧柏酮含量为0.32%～3.62%。     

Closing the ultrafine particle number concentration budget at road-to-ambient scale: Implications for particle dynamics

Freshly emitted vehicle exhaust particles are diluted quickly as they mix into ambient air, but the contribution of evaporation, coagulation, and/or nucleation of new particles to the number concentration has been the subject of some debate. We analyzed one-second time resolution size distribution data from an early morning field campaign, data collected at a time at which dilution has a smaller (but still dominant; ～70?80%) impact on particle concentrations. Because the plume is diluted over an hour, and a distance of 1500 m, we can constrain the processes with higher accuracy. We find that concentrations in the smaller size bins (5.6–23.7 nm) peak further downwind than the reference particles (42.1–562 nm), and decay significantly faster than larger particles particularly in the area 100?400 m downwind. Comparisons of the cumulative contributions of van der Waals enhanced coagulation, dry deposition, and dilution and the observed decay curves, imply that for up to the first 50–100 m there is nucleation and/or growth of particles smaller than 5.6 nm. In contrast, in the ～100–400 m region, some of the smaller particles evaporate. In the further downwind areas (>400 m) the particles all appear to decay at rates consistent with the sum of dilution, coagulation, and deposition. We also find that a dry deposition parameterization at the low end of those available in the literature is most consistent with the observational data.

© 2016 American Association for Aerosol Research     

Development of an evaluation method for quantitative driveability in heavy-duty vehicles

Subjective evaluations by experienced test drivers are primarily used to assess the driveability of vehicles in automotive companies. However, these evaluations are limited in terms of repeatability, incur costs, and require much time. Therefore, this study introduces a method of quantitatively evaluating the driveability of heavy-duty vehicles to circumvent these limitations. A vehicle experiment is conducted to measure data from an electronic control unit and an accelerometer to assess the driveability of heavy-duty vehicles. The evaluation indices for driveability are selected from previous studies on the objective and subjective methods of evaluating driveability according to various driving conditions. The indices include engine start, idle, acceleration, deceleration, constant speed, and start-up driving conditions. This research presents a quantitative evaluation method using the calculated values of each index and the correlated weighting factors of indices obtained from the regression analysis of the subjective evaluations. The driveability of heavy-duty vehicles is quantitatively evaluated under various driving conditions based on the proposed method. Results of the quantitative evaluation are similar to those of the subjective evaluations, and the proposed method is determined applicable in evaluating the driveability of heavy-duty vehicles.     

Multipoint scanning dual‐detection confocal microscopy for fast 3D volumetric measurement

We propose a multipoint scanning dual‐detection confocal microscopy (MS‐DDCM) system for fast 3D volumetric measurements. Unlike conventional confocal microscopy, MS‐DDCM can accomplish surface profiling without axial scanning. Also, to rapidly obtain 2D images, the MS‐DDCM employs a multipoint scanning technique, with a digital micromirror device used to produce arrays of effective pinholes, which are then scanned. The MS‐DDCM is composed of two CCDs: one collects the conjugate images and the other collects nonconjugate images. The ratio of the axial response curves, measured by the two detectors, provides a linear relationship between the height of the sample surface and the ratio of the intensity signals. Furthermore, the difference between the two images results in enhanced contrast. The normalising effect of the MS‐DDCM provides accurate sample heights, even when the reflectance distribution of the surface varies. Experimental results confirmed that the MS‐DDCM achieved high‐speed surface profiling with improved image contrast capability.     

Relation between etching profile and voltage–current shape of sintered SiC etching by atmospheric pressure plasma

Sintered silicon carbide (SiC) was etched by a dielectric barrier discharge source. A high voltage bipolar pulse was used with helium gas for the plasma generation. One stable filament plasma was generated and could be used for SiC etching. As the processing gas (NF₃) mixing rate increased, the width and depth of the etching profile became narrower and deeper. The differentiated V–Q Lissajous method was used for measuring the capacitances (C_eq) of the electrode after the plasma turned on. The width of the etching profile was proportional to C_eq. As the current peak value I_smx of the substrate current increased, the volume removal rate of SiC increased. The etch depth was proportional to the ratio of I_smx to C_eq. Additionally, because of the different characteristics of the plasma disks on SiC substrate by the voltage polarity, the etching profile was unstable. However, in high NF₃ mixing process, the etching profile became stable and deeper.     

Analysis of a clutch damper using a discrete model

It is important to have a precise model for the clutch damper in order to simulate the entire powertrain of a vehicle and predict the responses of the system. In this research, we developed a new model in which the spring used in the clutch damper is divided into a finite number of elements. The model takes many unique properties of arc-shaped springs into consideration and is anticipated to be more precise than conventional simple models. With the model, two meaningful results were presented which can be utilized afterwards. One is a simulation concerning the peak torque transmitted via the clutch damper. The other is a simulation that shows the hysteretic characteristics of the clutch damper.     

Numerical Modeling of a Spar Platform Tethered by a Mooring Cable

Virtual simulation is an economical and efficient method in mechanical system design. Numerical modeling of a spar platform, tethered by a mooring cable with a spherical joint is developed for the dyna...     

Antibacterial Effect of Glucose Oxidase on Growth of Pseudomonas fragi as Related to pH

The effect of glucose oxidase (GOX) catalyzed reaction with glucose on Pseudomonas fragi was analyzed in nutrient broth and fish extract media. Growth of P. fiugi in nutrient broth was clearly suppressed by 1.0, 2.0 and 4.0 mg/mL glucose when combined with 0.5–2.0 U/mL GOX. The same GOX/glucose combinations inhibited P. frasi growth in fish extract media. Viable cell numbers in fish media showed clear growth inhibition with combinations of l.0–2.0 U/mL GOX and 8.0–16.0 mg/mL glucose. Higher GOX and glucose rapidly produced 2.0–2.5 unit decreases in pH, but produced enough gluconic acid to precipitate fish proteins. Use of 0.5 U/mL GOX in fish extract media resulted in slow, sustained activity with potential for inhibition of microbial growth in foods without excessive acidity.     

Fault-Tolerant UAV Data Acquisition Schemes

Wireless Personal Communications - Through the use of UAV, the functional lifetime of WSN can be elongated in exchange for higher data delivery latency as the UAV replaces the multi-hop...