Hydrocarbon condensation in heavy-duty diesel exhaust

The semivolatile mass fraction of diesel exhaust particles was studied using size-resolved on-line techniques (DMA-ELPI; TDMA-ELPI). The average density of the semivolatile liquid on the particles was measured to be approximately 0.8 g/cm3. The measured size resolved values of mass transfer imply that condensation, or diffusion-limited mass transfer, plays a major role in driving the volatile matter to the diesel exhaust particles. The measured mass change values correspond to highly size dependent mass fractions for the semivolatile component, ranging from approximately 20-80%. Integrated over particle size distribution, the volatile mass fractions were 25 and 45% for the two load points studied. Calculation, based on the measured particle properties, indicates that only 10% volatile mass fraction could be explained by monolayer adsorption. The size resolved changes in particle effective density, fractal dimension, volatile mass fractions and mass are all in agreement with theoretical considerations of condensation.     

IR-wavelength optical shutter based on ITO/VO2/ITO thin film stack

Two thin film IR-shutter structures based on ITO-VO₂-ITO and ITO-VO₂ thin film stacks were designed. Thin film structures of the shutters were optimized at the wavelength of 1550 nm. The switch operation of the components was based on the metal-insulator transition phenomenon of VO₂. Shutter components were current controlled and the metal-insulator transition was induced by Joule heating effect. All the thin films were deposited by using pulsed laser deposition. Crystal structure, morphology, and optical characteristics of the produced components were studied. Components with three-layer structure were found to suffer from significant internal strain, which was relaxed by post-annealing the components in the furnace. The maximum change of the optical transmittance measured at the wavelength of 1550 nm from the three-layer components during the switch cycle was 26.5%. The corresponding value measured from two-layer component??s structure was 34.2%. The maximum modulation of the transmittance of the three-layer component was reached at the wavelength of 1250 nm, which was 34%.     

Fabrication of optical inverted-rib waveguides using UV-imprinting

In this paper we introduce a fabrication process for polymer rib waveguides that uses UV-imprint lithography. In the structure of an inverted-rib waveguide, the lower cladding of the waveguide is patterned by UV-imprinting and the waveguiding layer is subsequently spin-coated. That makes the thickness of the formed slab layer on the rib waveguide controllable by tuning the spin-coating parameters. The fabrication process utilizes two steps of UV-imprinting. The first one is to form a rigid polymer mold from positive tone photoresist. The second one is to pattern the waveguide lower cladding with the formed polymer mold. Through the two steps of UV-imprinting, rib waveguides can be fabricated without an etching procedure. We demonstrated the proposed fabrication process by fabricating 2-μm-wide waveguides operating in single mode at 1310 nm. With TE-polarized light, the fabricated waveguides show an average transmission of 58.6% in a 30 mm long waveguide, corresponding to a loss of 2.3 dB.     

Effect of oxidation catalysts on diesel soot particles

The effect of a conventional oxidation catalyst and a novel particle oxidation catalyst (POC) on diesel particles is studied using identical methodology. Regulated particulate matter emission measurement is followed by analyzing soluble organic fraction. In addition, size distributions are measured using a partial flow sampling system with a thermodenuder as an option. A parallel ELPI-SMPS method is used to study the particle effective density and, further, the mass. Tests are conducted using a heavy duty diesel engine with a very low sulfur fuel. A decrease in particle mass was observed when using a catalyst. When using a conventional catalyst the decrease was attributed to the decrease of soluble organic fraction, while using POC the nonsoluble fraction was also found to decrease, by 8-38%. This observation is confirmed by particle number measurement, and POC was found to decrease the dry particle number concentration measured downstream of a thermodenuder by 13-28%. Further particle structure analysis indicated lower density values when using conventional catalyst or POC. The physical size of the particles was not changed noticeably over either catalyst--implying the soluble organic fraction was condensed onto the soot, filling the voids in the porous structure of soot agglomerates, when no catalyst is used.     

Incorporating Hydrologic Uncertainty in Industrial Economic Models: Implications of Extreme Rainfall Variability on Metal Mining Investments

Water balance uncertainties have long been known to lead to potential environmental hazards, but their effect on economic profitability of mines is an under-studied field of research. Historical rainfall data are analyzed using the extreme value theory (EVT) and the peak over threshold method (POT). The resulting distributions are used as inputs into a system dynamics techno-economic metal mining investment profitability model, and simulation analysis is performed. The proposed methodology incorporates rainfall extremes and uncertainty into techno-economic modeling of metal mining operations. A case study with real-life historical rainfall data was used to illustrate the relationship between hydrologic uncertainty and the economic value of a metal mining investment.

     

Structure–Activity Relationships of 1-Benzoylazulenes at the OX1 and OX2 Orexin Receptors

We previously demonstrated the potential of di- or trisubstituted azulenes as ligands (potentiators, weak agonists, and antagonists) of the orexin receptors. In this study we investigated 27 1-benzoylazulene derivatives, uncovering seven potentiators of the orexin response on OX₁ and two weak dual orexin receptor agonists. For potentiators, replacement of the azulene scaffold by indole retained the activity of four out of six compounds. The structure–activity relationships for agonism and potentiation can be summarized into a bicyclic aromatic ring system substituted with two hydrogen-bond acceptors (1-position, benzoyl; 6-position, carboxyl/ester) within 7–8 Å of each other; a third acceptor at the 3-position is also well tolerated. The same pharmacophoric signature is found in the preferred conformations of the orexin receptor agonist Nag26 from molecular dynamics simulations. Subtle changes switch the activity between weak agonism and potentiation, suggesting overlapping binding sites.     

An alternative for the implementation of Kruskal's minimal spanning tree algorithm

An application of the bucket sort in Kruskal's minimal spanning tree algorithm is proposed. The modified algorithm is very fast if the edge costs are from a distribution which is close to uniform. This is due to the fact that the sorting phase then takes for an m edge graph an O(m) average time. The O(m log m) worst case occurs when there is a strong peak in the distribution of the edge costs.     

Determination of strawberry volatiles with low resolution gas phase FT–IR analyser

A low-resolution gas phase Fourier transform infrared (FT-IR) analyser, designed for industrial and environmental applications, was applied to the analysis of volatile compounds of strawberry. The frozen fruit was thawed, mashed and transferred into a glass bottle mounted to a sampling system. Volatile compounds were collected by gently heating in a vacuum and then removed into the sample cell of the gas analyser at atmospheric pressure. The quantitative analysis of 14 compounds in all was performed by a built-in microcomputer applying multicomponent analysis. GC-MS applying dynamic headspace sampling was used as a reference method. A spectral library consisting of 24 typical aroma volatiles of strawberry was created before the analyses. The highest proportions were measured for acetone and 2,5-dimethyl-4-hydroxy-3(2H)-furanone. The average coefficient of variation (CV) of the relative amount of all the compounds was 35%, that of acetone being the lowest, 3.3%. Significant differences between strawberry varieties were noticed.     

Optimization of a microphone for photoacoustic spectroscopy

The principles of optimizing a microphone for a photoacoustic detector in the nonresonant mode of operation are presented. Performance of the constructed optical cantilever microphone is compared to the commercial electret microphone by measuring the photoacoustic spectrum of methane with both systems. The sensitivity of the presented photoacoustic detector in the nonresonant mode of operation is 100 times higher with the optical cantilever microphone than with the electret microphone.     

Construction of patient-specific surface models from MR images: application to bioelectromagnetism

Patient-specific geometric models are needed in many engineering problems. This work reports a novel software tool developed to construct individualized triangulated surface models from MR images. The program consists of three main parts: segmentation, triangulation and registration. The software tool was developed under the UNIX operating system. The application area demonstrated in this work is bioelectromagnetism but the program can be used as well in other engineering problems. The tool has been successfully applied in numerous cases, both for the thorax and the head.