Measurement, modeling and perception of painted surfaces : A Multi-scale analysis of the touch-up problem

Real-world surfaces typically have geometric features at a range of spatial scales. At the microscale, opaque surfaces are often characterized by bidirectional reflectance distribution functions (BRDF), which describes how a surface scatters incident light. At the mesoscale, surfaces often exhibit visible texture - stochastic or patterned arrangements of geometric features that provide visual information about surface properties such as roughness, smoothness, softness, etc. These textures also affect how light is scattered by the surface, but the effects are at a different spatial scale than those captured by the BRDF. Through this research, we investigate how microscale and mesoscale surface properties interact to contribute to overall surface appearance. This behavior is also the cause of the well-known touch-up problem in the paint industry, where two regions coated with exactly the same paint, look different in color, gloss and/or texture because of differences in application methods. At first, samples were created by applying latex paint to standard wallboard surfaces. Two application methods- spraying and rolling were used. The BRDF and texture properties of the samples were measured, which revealed differences at both the microscale and mesoscale. This data was then used as input for a physically-based image synthesis algorithm, to generate realistic images of the surfaces under different viewing conditions. In order to understand the factors that govern touch-up visibility, psychophysical tests were conducted using calibrated, digital photographs of the samples as stimuli. Images were presented in pairs and a two alternative forced choice design was used for the experiments. These judgments were then used as data for a Thurstonian scaling analysis to produce psychophysical scales of visibility, which helped determine the effect of paint formulation, application methods, and viewing and illumination conditions on the touch-up problem. The results can be used as base data towards development of a psychophysical model that relates physical differences in paint formulation and application methods to visual differences in surface appearance

Large Eddy Simulation and Analysis of Shear Flows in Complex Geometries

In the present work, large eddy simulation is used to numerically investigate two types of shear flows in complex geometries, (i) a novel momentum driven countercurrent shear flow in dump geometry and (ii) a film cooling flow (inclined jet in crossflow). Verification of subgrid scale model is done through comparisons with measurements for a turbulent flow over back step, present cases of counter current shear and film cooling flow. In the first part, a three dimensional stability analysis is conducted for countercurrent shear flow using Dynamic mode decomposition and spectral analysis. Kelvin-Helmholtz is identified as primary instability mechanism and observed as global mode at a specific parameter. Mechanism of global mode synchronization over distinct spatial location is studied. In the second part, the flow physics of film cooling flows is analysed. The origin, evolution of various coherent flow structures and their role in film cooling heat transfer is studied based on detailed flow visualization. Further, the contribution of coherent structures in film cooling heat transfer and mixing is studied through modal analysis. Low frequency modes are found to have large contribution in cooling surface adiabatic temperature fluctuation while high frequency modes play larger role in bulk mixing. Finally, a new contoured crater shape is developed and shown to have improved performance at shallow depth compared to earlier designs

Enhanced Photorefractivity in a Polymeric Composite Photosensitized with Carbon Nanotubes Grafted to a Photoconductive Polymer

We report on the photosensitization of photorefractive (PR) polymeric composites through the inclusion of multiwalled and singlewalled carbon nanotubes (CNTs), respectively, having poly(N -vinyl carbazole) (PVK) grafted to their surfaces. The PR nature of the holographic gratings was confirmed via the asymmetric exchange of energy in a two-beam-coupling (TBC) geometry, yielding TBC gain coefficients approaching 80 cm-1. In addition, in degenerate-four-wave- mixing experiments the prepared composites exhibited diffraction efficiencies as high as 60% and overmodulation voltages as low as ∼40 V/μm. These notable figures of merit indicate that the grafting of the PVK polymer to the various CNTs results in enhanced PR performance. The mechanism responsible for this enhancement in PR performance is investigated using a variety of experimental techniques

Deflagrative, Auto-ignitive, and Detonative Propagation Regimes in Engines

The paper presents a novel overall quantitative description of the major regimes of engine combustion, covering the influences of both turbulence and auto-ignition parameters on burn rates and flame extinctions. It involves two separate, yet interconnected, correlation diagrams. The first involves the normalized turbulent burning velocity, the Karlovitz stretch factor the strain rate Markstein number, and also includes possible relative auto-ignitive burn rates. The second is a complementary correlating ξ/ɛ diagram, involving the auto-ignitive parameters of ignition delay and excitation times. The ξ parameter is the acoustic speed normalized by the auto-ignition velocity, while ɛ is the acoustic wave residence time in a hot spot, normalized by the excitation, or heat release, time. It also includes an indication of the regime of normal flame propagation. The different auto-ignitive regimes, in which a variety of contrasting fuel/air mixtures might operate, are indicated on the ξ/ɛ diagram, particularly in relation to its peninsula of developing detonation at a hot spot. Operational points, measured on a variety of engines, are also shown on the two diagrams, in terms of the different regimes, including those of mild and “super-knock”, turbulent flame extinctions, and controlled auto-ignition

Mechanisms of interaction of non-thermal plasma with living cells

Thermal plasmas and lasers have been widely used in medicine to cut, ablate and cauterize tissues through heating; in contrast, non-thermal plasma produces various highly active molecules and atoms without heat. As a result, its effects on living cells and tissues could be selective and tunable. This makes non-thermal plasma very attractive for medical applications. However, despite several interesting demonstrations of non-thermal plasma in blood coagulation and tissue sterilization, the biological and physical mechanisms of its interaction with living cells are still poorly understood impeding further development of non-thermal plasma as a clinical tool. Although several possible mechanisms of interaction have been suggested, no systematic experimental work has been performed to verify these hypotheses.Using cells in culture, it is shown in this work that non-thermal plasma created by dielectric barrier discharge (DBD) has dose-dependent effects ranging from increasing cell proliferation to inducing apoptosis which are consistent with the effects of oxidative stress. DNA damage is chosen as a marker to assess the effects of oxidative stress in a quantitative manner. It is demonstrated here that plasma induced DNA damage as well as other effects ranging from cell proliferation to apoptosis are indeed due to production of intracellular reactive oxygen species (ROS). We found that DNA damage is initiated primarily by plasma generated active neutral species which cannot be attributed to ozone alone. Moreover, it is found that extracellular media and its components play a critical role in the transfer of the non-thermal plasma initiated oxidative stress into cells. Specifically, it is found that the peroxidation efficiency of amino acids is the sole predictor of the ability of the medium to transfer the oxidative stress induced by non-thermal plasma.Phosphorylation of H2AX, a DNA damage marker, following plasma treatment is found to be ATR dependent and ATM independent, suggesting that non-thermal plasma may induce formation of bulky lesions unlike ionizing radiation (IR) or H2O2 which primarily produce DNA double strand breaks. Moreover, it is found that the pathway by which plasma generated oxidative stress is transferred across cellular membranes does not involve lipid peroxidation by-products, although lipid peroxidation does occur.Ph.D., Electrical Engineering -- Drexel University, 201

The mealybug chromosome system I: unusual methylated bases and dinucleotides in DNA of a Planococcus species

The methylation status of the nuclear DNA from a mealybug, a Planococcus species, has been studied. Analysis of this DNA by High Performance Liquid Chromatography and Thin Layer Chromatography revealed the presence of significant amounts of 5--methylcytosine. Since analysis of DNA methylation using the Msp I/Hpa II system showed only minor differences in susceptibility of the DNA to the two enzymes, it seemed possible that 5-methylcytosine (5mC) occurred adjacent to other nucleotides in addition to its usual position, next to guanosine. This was verified by dinucleotide analysis of DNA labelledin vitro by nick translation. These data show that the total amount of 5-methylcytosine in this DNA is slightly over 2.3 mol %, of which 0.61% occurs as the dinucleotide 5mCpG, 0.68% as 5mCpA, 0.59% as 5mCpT and 0.45% as 5mCpC. 5mCpG represents approximately 3.3% of all CpG dinucleotides. The experimental procedure would not have permitted the detection of 5mCp5mC, if it occurs in this system. Unusually high amounts of 6-methyladenine (approximately 4 mol %) and 7-methylguanine (approximately 2 mol %) were also detected, 6-methyladenine and 7-methylguanine occurred adjacent to all four nucleotides. The total G+C content was 33.7% as calculated from dinucleotide data and 32.9% as determined from melting profiles

Analysis of a series hybrid vehicle concept that combines low temperature combustion and biofuels as power source

[EN] This work evaluates the potential of a series hybrid vehicle concept that combines low temperature combustion (LTC) and biofuels as power source. To do this, experimental data from a previous work obtained in a singlecylinder engine running under ethanol-diesel dual-fuel combustion is used. Then, vehicle systems simulations are used to estimate performance and emissions of the LTC hybrid vehicle and compare them versus conventional diesel combustion (CDC). The vehicle selected to perform the simulations is the Opel Vectra, which equips the compression ignition engine used in the experimental tests. The results from the simulations used for the analysis are firstly optimized by combining design of experiments and the Kriging fitting method. The multi-objective optimization allows to determine some characteristics and controls of the hybrid vehicle. The comparison of the estimated performance and emissions of the LTC-hybrid concept versus CDC over the worldwide harmonized light vehicles test cycle (WLTC) and real driving cycle (RDE) revealed clear benefits in terms of energy consumption, CO2 and NOx and soot emissions. In this sense, the hybrid concept enabled a reduction of the final energy consumed of 3% in the RDE cycle and 6.5% in the WLTC as compared to CDC. In terms of engine-out emissions, the CO2 was reduced around 16% versus CDC, and engine-out NOx and soot were reduced below the levels imposed by the Euro 6 regulation. As a penalty, the engine-out HC and CO emissions increased to more than double than CDC. However, based on previous experimental results, it is expected that a conventional diesel oxidation catalyst can reduce the tail-pipe HC and CO levels below the Euro 6 limits.The authors gratefully acknowledge General Motors Global Research & Development for providing the engine used to acquire the experimental data shown in this investigation. The authors also acknowledge FEDER and Spanish Ministerio de Economía y Competitividad for partially supporting this research through TRANCO project (TRA2017- 87694-R).García Martínez, A.; Monsalve-Serrano, J. (2019). Analysis of a series hybrid vehicle concept that combines low temperature combustion and biofuels as power source. Results in Engineering. 1:1-12. https://doi.org/10.1016/j.rineng.2019.01.001S1121Kalghatgi, G. (2018). Is it really the end of internal combustion engines and petroleum in transport? Applied Energy, 225, 965-974. doi:10.1016/j.apenergy.2018.05.076Singh, S., & Kennedy, C. (2015). Estimating future energy use and CO2 emissions of the world’s cities. Environmental Pollution, 203, 271-278. doi:10.1016/j.envpol.2015.03.039Engel, M. S., Paas, B., Schneider, C., Pfaffenbach, C., & Fels, J. (2018). Perceptual studies on air quality and sound through urban walks. Cities, 83, 173-185. doi:10.1016/j.cities.2018.06.020Guanetti, J., Formentin, S., Corno, M., & Savaresi, S. M. (2017). Optimal energy management in series hybrid electric bicycles. Automatica, 81, 96-106. doi:10.1016/j.automatica.2017.03.021He, H., & Guo, X. (2018). Multi-objective optimization research on the start condition for a parallel hybrid electric vehicle. Applied Energy, 227, 294-303. doi:10.1016/j.apenergy.2017.07.082García Valladolid, P., Tunestål, P., Monsalve-Serrano, J., García, A., & Hyvönen, J. (2017). Impact of diesel pilot distribution on the ignition process of a dual fuel medium speed marine engine. Energy Conversion and Management, 149, 192-205. doi:10.1016/j.enconman.2017.07.023Wu, H.-W., Wang, R.-H., Ou, D.-J., Chen, Y.-C., & Chen, T. (2011). Reduction of smoke and nitrogen oxides of a partial HCCI engine using premixed gasoline and ethanol with air. Applied Energy, 88(11), 3882-3890. doi:10.1016/j.apenergy.2011.03.027Olmeda, P., García, A., Monsalve-Serrano, J., & Lago Sari, R. (2018). Experimental investigation on RCCI heat transfer in a light-duty diesel engine with different fuels: Comparison versus conventional diesel combustion. Applied Thermal Engineering, 144, 424-436. doi:10.1016/j.applthermaleng.2018.08.082Yao, M., Zheng, Z., & Liu, H. (2009). Progress and recent trends in homogeneous charge compression ignition (HCCI) engines. Progress in Energy and Combustion Science, 35(5), 398-437. doi:10.1016/j.pecs.2009.05.001Maurya, R. K., & Agarwal, A. K. (2011). Experimental investigation on the effect of intake air temperature and air–fuel ratio on cycle-to-cycle variations of HCCI combustion and performance parameters. Applied Energy, 88(4), 1153-1163. doi:10.1016/j.apenergy.2010.09.027Singh, A. P., & Agarwal, A. K. (2012). Combustion characteristics of diesel HCCI engine: An experimental investigation using external mixture formation technique. Applied Energy, 99, 116-125. doi:10.1016/j.apenergy.2012.03.060Yang, Y., Dec, J. E., Dronniou, N., & Sjöberg, M. (2011). Tailoring HCCI heat-release rates with partial fuel stratification: Comparison of two-stage and single-stage-ignition fuels. Proceedings of the Combustion Institute, 33(2), 3047-3055. doi:10.1016/j.proci.2010.06.114Benajes, J., García, A., Monsalve-Serrano, J., Balloul, I., & Pradel, G. (2017). Evaluating the reactivity controlled compression ignition operating range limits in a high-compression ratio medium-duty diesel engine fueled with biodiesel and ethanol. International Journal of Engine Research, 18(1-2), 66-80. doi:10.1177/1468087416678500García, A., Monsalve-Serrano, J., Rückert Roso, V., & Santos Martins, M. E. (2017). Evaluating the emissions and performance of two dual-mode RCCI combustion strategies under the World Harmonized Vehicle Cycle (WHVC). Energy Conversion and Management, 149, 263-274. doi:10.1016/j.enconman.2017.07.034Benajes, J., García, A., Monsalve-Serrano, J., & Villalta, D. (2018). Exploring the limits of the reactivity controlled compression ignition combustion concept in a light-duty diesel engine and the influence of the direct-injected fuel properties. Energy Conversion and Management, 157, 277-287. doi:10.1016/j.enconman.2017.12.028Benajes, J., García, A., Monsalve-Serrano, J., Balloul, I., & Pradel, G. (2016). An assessment of the dual-mode reactivity controlled compression ignition/conventional diesel combustion capabilities in a EURO VI medium-duty diesel engine fueled with an intermediate ethanol-gasoline blend and biodiesel. Energy Conversion and Management, 123, 381-391. doi:10.1016/j.enconman.2016.06.059Benajes, J., García, A., Monsalve-Serrano, J., & Boronat, V. (2016). Dual-Fuel Combustion for Future Clean and Efficient Compression Ignition Engines. Applied Sciences, 7(1), 36. doi:10.3390/app7010036Benajes, J., García, A., Monsalve-Serrano, J., & Boronat, V. (2017). An investigation on the particulate number and size distributions over the whole engine map from an optimized combustion strategy combining RCCI and dual-fuel diesel-gasoline. Energy Conversion and Management, 140, 98-108. doi:10.1016/j.enconman.2017.02.073Benajes, J., García, A., Monsalve-Serrano, J., & Boronat, V. (2017). Gaseous emissions and particle size distribution of dual-mode dual-fuel diesel-gasoline concept from low to full load. Applied Thermal Engineering, 120, 138-149. doi:10.1016/j.applthermaleng.2017.04.005Curran S, Hanson R, Wagner R. Reactivity controlled compression ignition combustion on a multi-cylinder light-duty diesel engine. Int. J. Engine Res. 13 (3), 216-225.Reitz, R. D., & Duraisamy, G. (2015). Review of high efficiency and clean reactivity controlled compression ignition (RCCI) combustion in internal combustion engines. Progress in Energy and Combustion Science, 46, 12-71. doi:10.1016/j.pecs.2014.05.003Olmeda, P., Martin, J., Garcia, A., Villalta, D., Warey, A., & Domenech, V. (2017). A Combination of Swirl Ratio and Injection Strategy to Increase Engine Efficiency. SAE International Journal of Engines, 10(3), 1204-1216. doi:10.4271/2017-01-0722Luján, J. M., Bermúdez, V., Dolz, V., & Monsalve-Serrano, J. (2018). An assessment of the real-world driving gaseous emissions from a Euro 6 light-duty diesel vehicle using a portable emissions measurement system (PEMS). Atmospheric Environment, 174, 112-121. doi:10.1016/j.atmosenv.2017.11.056OLIVER, M. A., & WEBSTER, R. (1990). Kriging: a method of interpolation for geographical information systems. International journal of geographical information systems, 4(3), 313-332. doi:10.1080/02693799008941549Benajes, J., García, A., Monsalve-Serrano, J., & Villalta, D. (2018). Benefits of E85 versus gasoline as low reactivity fuel for an automotive diesel engine operating in reactivity controlled compression ignition combustion mode. Energy Conversion and Management, 159, 85-95. doi:10.1016/j.enconman.2018.01.015García, A., Piqueras, P., Monsalve-Serrano, J., & Lago Sari, R. (2018). Sizing a conventional diesel oxidation catalyst to be used for RCCI combustion under real driving conditions. Applied Thermal Engineering, 140, 62-72. doi:10.1016/j.applthermaleng.2018.05.04

Effects of low reactivity fuel characteristics and blending ratio on low load RCCI (reactivity controlled compression ignition) performance and emissions in a heavy-duty diesel engine

This work investigates the effect of low reactivity fuel characteristics and blending ratio on low load RCCI (reactivity controlled compression ignition) performance and emissions using four different low reactivity fuels: E10-95, E10-98, E20-95 and E85 (port fuel injected) while keeping constant the same high reactivity fuel: diesel B7 (direct injected). The experiments were conducted using a heavy-duty single-cylinder research diesel engine adapted for dual fuel operation. All tests were carried out at 1200 rev/min and constant CA50 of 5 CAD ATDC. For this purpose, the premixed energy was equal for the different blends and the EGR (exhaust gas recirculation) rate was modified as required, keeping constant the rest of engine settings. In addition, a detailed analysis of air/fuel mixing process has been developed by means of a 1-D spray model. Results suggest that in-cylinder fuel reactivity gradients strongly affect the engine efficiency at low load. Specifically, a reduced reactivity gradient allows an improvement of 4.5% in terms of gross indicated efficiency when the proper blending ratio is used. In addition, EURO VI NOx and soot emission levels are fulfilled with a strong reduction in CO and HC compared with the case of the higher reactivity gradient among the low and high reactivity fuel.The authors acknowledge VOLVO Group Trucks Technology and TOTAL for supporting this research.Benajes Calvo, JV.; Molina, S.; García Martínez, A.; Monsalve Serrano, J. (2015). Effects of low reactivity fuel characteristics and blending ratio on low load RCCI (reactivity controlled compression ignition) performance and emissions in a heavy-duty diesel engine. Energy. 90:1261-1271. doi:10.1016/j.energy.2015.06.088S126112719

Transport and infrared photoresponse properties of InN nanorods/Si heterojunction

The present work explores the electrical transport and infrared (IR) photoresponse properties of InN nanorods (NRs)/n-Si heterojunction grown by plasma-assisted molecular beam epitaxy. Single-crystalline wurtzite structure of InN NRs is verified by the X-ray diffraction and transmission electron microscopy. Raman measurements show that these wurtzite InN NRs have sharp peaks E2(high) at 490.2 cm-1 and A1(LO) at 591 cm-1. The current transport mechanism of the NRs is limited by three types of mechanisms depending on applied bias voltages. The electrical transport properties of the device were studied in the range of 80 to 450 K. The faster rise and decay time indicate that the InN NRs/n-Si heterojunction is highly sensitive to IR light