Modal decomposition for the analysis of the rotor-stator interactions in multistage compressors

A modal analysis method of the rotor-stator interactions in multistage compressors has been developed by LMFA.This method,based on a double modal decomposition of the flow over space and time,has been applied to nu-merical and experimental results of the high-speed 3?-stage compressor CREATE based at LMFA,Lyon-France.It reveals the presence of a very strong rotor-stator interaction which completely drives the flow at casing behind all the rotors.This modal analysis method applied to an unsteady RANS simulation permits to calculate the en-ergy of the rotor-stator interactions and to plot energetic meridian maps to explain experimental results and to analyze the interaction in the whole machine.     

Actual heating energy savings in thermally renovated Dutch dwellings

The register of the Dutch social housing stock was analysed, containing 300.000 dwellings, renovated between 2010 and 2013. The main objective was twofold: to evaluate the performance gap in these dwellings before and after the renovation and to establish what renovation measures achieve the highest reduction of consumption, particularly in practice (actual savings). The results showed large performance gaps in dwellings with low R and high U values, local heating systems, changes from a non-condensing into a condensing boiler and upgrades to a natural ventilation system. Regarding the actual effectiveness of renovation measures, replacement of old gas boilers with more efficient ones yields the highest energy reduction, followed by deep improvements of windows. Installing mechanical ventilation yields a small reduction compared to other measures, but still much larger than theoretically expected. The paper shows once more that the calculation method currently in use cannot be considered accurate if compared to actual consumption. The study demonstrated that unrealistic theoretical efficiencies of heating systems and insulation values are causing a part of the performance gap. Nowadays, large datasets of buildings thermal performance and actual consumption offer an opportunity to improve these misconceptions.     

A theoretical study on the charge transport properties of DNA

The charge transport properties of DNA are studied by the first-principle simulation to discuss the possibility of applying DNA to molecular wire. Both the hopping model and band-like model are introduced. By using hopping model, the theoretical hole mobilities calculated by Marcus theory between the same bases in DNA are 5.6 × 10⁻³, 4.1 × 10⁻², 2.0 × 10⁻² and 1.2 × 10⁻⁴ cm²V⁻¹s⁻¹ for T-T, A-A, C-C and G-G; and the calculated electron mobilities are 5.3 × 10⁻⁸, 1.5 × 10⁻⁴, 8.1 × 10⁻⁷ and 7.5 × 10⁻¹⁰ cm²V⁻¹s⁻¹ for T-T, A-A, C-C and G-G, respectively. And the charge transport for both holes and electrons between different bases exhibits directivity. By using band-like model, we calculated the band width of DNA with double helix structure and bilinear structure to investigate which structure will facilitate to the charge transport. We found that the band width of DNA increased when DNA transforming from the double helix structure to the bilinear structure, which means DNA with the bilinear structure possesses better charge transport properties. This research sheds a light on the molecular design for the molecule serving as the molecular wire.     

A Model Coupling Method for Shape Prediction

 The shape of strip is calculated by iterative method which combines strip plastic deformation model with rolls elastic deformation model through their calculation results, which can be called results coupling method. Because the shape and rolling force distribution are very sensitive to strip thickness transverse distribution′s variation, the iterative course is rather unstable and sometimes convergence cannot be achieved. In addition, the calculating speed of results coupling method is low, which restricts its usable range. To solve the problem, a new model coupling method is developed, which takes the force distribution between rolls, rolling force distribution and strip′s exit transverse displacement distribution as basic unknowns, and integrates strip plastic deformation model and rolls elastic deformation model as a unified linear equations through their internal relation, so the iterative calculation between the strip plastic deformation model and rolls elastic deformation model can be avoided. To prove the effectiveness of the model coupling method, two examples are calculated by results coupling method and model coupling method respectively. The results of front tension stress, back tension stress, strip′s exit gauge, the force between rolls and rolling force distribution calculated by model coupling method coincide very well with results coupling method. However the calculation course of model coupling method is more steady than results coupling method, and its calculating speed is about ten times as much as the maximal speed of results coupling method, which validates its practicability and reliability.     

Evaluation of pedestrian safety at intersections: A theoretical framework based on pedestrian-vehicle interaction patterns

Pedestrians are the most vulnerable road users, and pedestrian safety has become a major research focus in recent years. Regarding the quality and quantity issues with collision data, conflict analysis using surrogate safety measures has become a useful method to study pedestrian safety. However, given the inequality between pedestrians and vehicles in encounters and the multiple interactions between pedestrians and vehicles, it is insufficient to simply use the same indicator(s) or the same way to aggregate indicators for all conditions. In addition, behavioral factors cannot be neglected.To better use information extracted from trajectories for safety evaluation and pay more attention on effects of behavioral factors, this paper develops a more sophisticated framework for pedestrian conflict analysis that takes pedestrian-vehicle interactions into consideration. A concept of three interaction patterns has been proposed for the first time, namely ⿿hard interaction,⿿ ⿿no interaction,⿿ and ⿿soft-interaction.⿿ Interactions have been categorized under one of these patterns by analyzing profiles of speed and conflict indicators during the whole interactive processes. In this paper, a support vector machine (SVM) approach has been adopted to classify severity levels for a dataset including 1144 events extracted from three intersections in Shanghai, China, followed by an analysis of variable importance. The results revealed that different conflict indicators have different contributions to indicating the severity level under various interaction patterns. Therefore, it is recommended either to use specific conflict indicators or to use weighted indicator aggregation for each interaction pattern when evaluating pedestrian safety.The implementation has been carried out at the fourth crosswalk, and the results indicate that the proposed method can achieve a higher accuracy and better robustness than conventional methods. Furthermore, the method is helpful for better understanding underlying levels of safety from the behavioral perspective, which can also provide evidence for targeted traffic education on proper behaviors.     

Online social networks for health behaviour change: Designing to increase socialization

Positive health behaviour by eating nutritious foods and performing physical activity has been shown to have significant benefit. Furthermore, theoretical models show that social factors contribute to health behaviour. However, social technology for health behaviour has provided limited social interaction. This paper presents an online social network for health behaviour change called VivoSpace that was designed from a theoretical foundation. The results from a field study (n = 35) are presented that include participants from both clinical and non-clinical settings. The results show that there was a significant change in some of the individual determinants for health behaviour change; however, social determinants did not change. Furthermore, the social features such as commenting were under utilized. Two follow-up focus groups (n = 7 and 8) were conducted to determine how the design should be iterated to increase socialization on VivoSpace. The results suggest that the posts need to add interest through system intelligence and allowing the user to add photos and other information to the post.     

Long term results of Epi-LASIK and LASEK for myopia

PurposeTo evaluate the long term clinical and confocal results of mechanical (Epi-LASIK) versus alcohol-assisted laser epithelial keratomileusis (LASEK) for correction of myopia.SettingGazi University Medical School, Department of Ophthalmology, Ankara, Turkey.DesignRetrospective study.MethodsTwenty-two eyes treated with LASEK and twenty eyes treated with Epi-LASIK were evaluated with a mean follow-up duration of 45 months. Mechanical separation of the epithelium was performed with Lasitome epithelial separator, and alcohol-assisted separation with 25 s application of 18% alcohol. Laser ablation was performed with the ESIRIS laser. All patients were examined daily until epithelial closure; at 1, 3, 6, and 12 months; and every year subsequently. Main outcome measures were uncorrected visual acuity (UCVA), manifest refraction, haze, and gray scale value in confocal microscopy, efficacy and safety indexes.ResultsPreoperative myopic spherical equivalent refraction was −4.65 ± 1.74 D in the LASEK and −3.87 ± 1.30 D in the Epi-LASIK-treated eyes (p = 0.36). Of both LASEK and Epi-LASIK-treated eyes, 95% achieved 20/25 or better final UCVA. The grade of haze and mean gray scale value in confocal microscopy were similar in LASEK and Epi-LASIK-treated eyes at all postoperative periods. The efficacy index was 0.94 in LASEK group and 0.96 in Epi-LASIK group (p = 0.44). The safety index was 1.01 in LASEK group and 1.02 in Epi-LASIK group (p = 0.42).ConclusionsBoth LASEK and Epi-LASIK offer safe and effective correction of myopia in the long term.     

Memristor emulator with tunable characteristic and its experimental results

In this study, operational transconductance amplifier (OTA) based simple and practical TiO₂ memristor emulator is presented. The proposed memristor emulator employs a multi-outputs OTA, an analog multiplier and a resistor and a capacitor. The parameters of the proposed memristor emulator can be tuned electronically by changing the biasing current of the OTA. Change of the transconductance gain of the OTA provides an advantage: “externally controllable memristor”. Non-volatile resistive switching characteristics and an application of this proposed memristor are given. Also, the memristor emulator is implemented using the commonly available OPA860. The effectiveness of the proposed memristor emulator is verified by the experimental results, which show good agreement with the theoretical and simulation results.     

Cu熔体中氧化夹杂在超重力场下的运动规律

对超重力场条件下Cu熔体中的氧化夹杂进行受力分析,建立夹杂颗粒沿超重力方向上的运动速度与运动距离方程,并通过理论计算分析重力系数、夹杂物特性(尺寸、种类、含量)以及熔体温度对夹杂物在超重力场中运动行为的影响。计算结果表明,超重力场能强化Cu熔体中氧化夹杂的定向分离过程,其中重力系数、夹杂物尺寸、夹杂与熔体之间密度差(固液密度差)对夹杂颗粒运动行为影响较大。较大的重力系数、夹杂物尺寸以及固液密度差均有利于夹杂物的上浮去除。     

微污染原水处理工艺设计及运行效果分析

针对原水有机微污染,桐乡运河水厂采用了生物预处理/强化常规处理/臭氧活性炭深度处理工艺,出水各项水质指标达标。介绍了该工程的设计参数,并详细分析了不同处理阶段对各污染指标的去除效果,可供相关工程参考。