Implementation of a Multi-Zone Numerical Blow-by Model and Its Integration with CFD Simulations for Estimating Collateral Mass and Heat Fluxes in Optical Engines

Nowadays reducing green-house gas emissions and pushing the fossil fuel savings in the field of light-duty vehicles is compulsory to slow down climate change. To this aim, the use of new combustion modes and dilution strategies to increase the stability of operations rich in diluent is an effective technique to reduce combustion temperatures and heat losses in throttled operations. Since the combustion behavior in those solutions highly differs from that of typical market systems, fundamental analyses in optical engines are mandatory in order to gain a deep understanding of those and to tune new models for improving the mutual support between experiments and simulations. However, it is known that optical accessible engines suffer from significant blow-by collateral flow due to the installation of the optical measure line. Thus, a reliable custom blow-by model capable of being integrated with both mono-dimensional and three-dimensional simulations was developed and validated against experimental data. The model can work for two different configurations: (a) stand-alone, aiming at providing macroscopic data on the ignitable mixture mass loss/recover through the piston rings; (b) combined, in which it is integrated in CFD engine simulations for the local analysis of likely collateral heat release induced by blow-by. Furthermore, once the model was validated, the effect of the engine speed and charge dilution on the blow-by phenomenon in the optical engine were simulated and discussed in the stand-alone mode.

AEROCOM/AEROSAT: an intercomparison of AAOD & SSA in model and satellite data

<p>Absorbing aerosol has the capacity to warm the climate, but the amount of warming is highly uncertain. AAOD (Absorptive Aeorosl Optical Depth) is an optical measure of the abundance of this absorbing aerosol, comprising mineral dust, black and brown carbon and can be retrieved from satellite measurements providing an almost global view on absorbing aerosol.</p><p>In this study we evaluate AEROCOM models with satellite observations of AAOD and SSA (Single Scattering Albedo) and interpret the discrepancies. Over source regions, diversity in model AAOD is mostly due to emissions even though models employ different assumptions regarding the imaginary refractive index. On the one hand this suggests emissions to be a major error source, on the other hand it suggests that the AEROCOM ensemble as a whole may have a bias with regards to MAC (Mass Absorption Coefficient). We show that in the models AAOD scales almost linearly with emissions (either black carbon or dust) and this allows the use of observations as a constraint.<span>  </span>In contrast, model diversity in AOD is shown to depend in almost equal measure on emissions, lifetimes and MECs (Mass Extinction Coefficient). We also analyse mineral dust and black carbon lifetimes by considering the contrast in AAOD over source regions and over outflow regions, and again provide observations constraints.</p><p>While the older Phase II models generally underestimate AAOD, Phase III models tend to straddle the observations, with some models over-estimating and other models underestimating AAOD. Emissions seem to be the driving factor in this difference. The amount of diversity is larger in the Phase III than Phase II models.</p><p>This study was conducted using four satellite datasets of AAOD and SSA. These datasets were extensively evaluated with AERONET. Dearth of observations prevents global assesment of the satellite retrievals. However, we show that model evaluation is relatively independent of the chosen dataset, even though we identify significant biases between the datasets.</p>

A Design of an Optical System of Liquid Filled Lens which can Adjust the Focus

The configuration of the system combines a liquid-filled lens, a flexible sensor membrane and a self-adjusted optical compensation device. We focus on optical compensation between the liquid-filled lens and the sensor membrane to make the system has good optical characters. For a single lens optical system, the curvy sensor membrane has better performance than flat type sensor in both the image quality of MTF, aberration and angle of view. To prove the idea, an optical measure system is developed and the optical system is also made. The experimental results show that this system do has a better performance in optical character.

An Auto-Focus Algorithm of Fast Search Based on Combining Rough and Fine Adjustment

A coarse and fine combined fast search and auto-focusing algorithm was suggested in this paper. This method can automatically search and find the focal plane by evaluating the image definition. The Krisch operator based edge energy function was used as the big-step coarse focusing, and then the wavelet transform based image definition evaluation function, which is sensitivity to the variation in image definition, was used to realize the small-step fine focusing in a narrow range. The un-uniform sampling function of the focusing area selection used in this method greatly reduces the workload and the required time for the data processing. The experimental results indicate that this algorithm can satisfy the requirement of the optical measure equipment for the image focusing.

Optical Measurement with Synchronous Calibration Standard in Air-Pipe Height Control System and its Optimization

Photogrammetric was widely used in engineering applications. But in a moving scene the standards’ position kept changed and accuracy of measurement would wave synchronously. To get a stable and precise optical measure system, a method using synchronously moving light standard with the camera was presented in this paper. The paper described the principle of measurement, the recognition algorithm and the height calculation. To meet the Real-time requirement a pre-computer method was used to optimize the calculation and to shorten the consume time. Experiments results show that the method has high accuracy and rapid detection speed to guarantee a constant clearance between the air pipe and uneven ground around railway.

Experiment on Thin Structure Behavior of Explosion Flame Flow Field

To prevent and control fire and explosion disasters, the premixed methane-air explosion was performed under restricted condition. In the experiment, the high speed schlieren photography system was used to record the flame characteristics and propagation mechanism. At the same time the ion current probe was used to reveal the inner flame structure characteristics. Based on the images of High Speed Schlieren Photography, the flame acceleration and flame structure were discussed in detail. In addition, the flow field characteristic of explosion flame was disclosed clearly. The microscopic evolving process of laminar-turbulent transition was accomplished in the period of flame structure change. As an alternative observation and detect technique, the high speed schlieren photograph system was used to capture flame front microstructure dynamic process precisely. Based on burning chemical and explosive dynamics, the optical measure method can record flame dynamic behavior visually, which further helps to disclose flame microstructure characteristic and the inner dynamic mechanism.

The multianalytic approach; or yes, you can get there from here! Problem solving in semiconductor manufacturing

Manufacturing, development and failure mode analysis problems, in the semiconductor industry, present unique challenges and opportunities, not only to utilize several analytical techniques, but to process and deprocess samples into an appropriate format for analysis. In today' s' cleanrooms a great deal of development is integrated into the manufacturing line. This, combined with the ever decreasing size and increasing density of components on a single integrated circuit, creates the need for accurate as well as precise measurements. The method of measure must be appropriate to the task, compatible with the manufacturing environment, and useful in a process control system.Current complimentary bipolar technologies, utilizing shallow junction implants, require additional as well as less robust processing in order to maintain the depth and latitude of the junction. Additional processing includes the formation of a contact window spacer. The spacer is formed, following implant and thermal anneal, by growing and subsequently removing a thermal oxide layer. In the manufacturing process, oxide removal is verified by optical measure using visible light.