Research on bioorganic fuels as power sources

This paper deals with the kind of the bioorganic fuel cells that are equipped with or without ion exchange membranes. The bioorganic materials of interest are alcohols (methanol, ethanol) and glucose, which are obtained from renewable energy sources such as biomass. The operation temperatures of the direct fuel cells cover from room temperature up to 150 °C. The direct bioorganic fuel cells belong to the subject area of ‘Advanced fuel cells’ of the Working group 4 in the EU COST Action 543 among the collaborating Universities and Institutes. Bioorganic fuel cells are suitable for application in small portable power sources, such as backups, battery chargers and in electronic devices. A number of current and earlier works are summarised and advances are highlighted in this area with special emphasis on glucose as a fuel.     

Heat and Mass Transfer Analogy Studies of Binary Liquid Mixture in Comparison with Eteanol-n-Heptane Evaporating to Air

ABSTRACT

An expenmental and theoretical study of heat and mass transfer analogy and a comparison of that to a binary liquid mixture evaporation is presented. Common organic solvents, ethanol and n-heptane, were used to form an alcohol - hydrocarbon mixture. Studies were carried out in a horizontal rectangular channel having air flow velocities of 0.2 – 0.9 m/s. Heat transfer coefficients were measured with a copper plate resistor and mass transfer coefficients with a square pool. The heat and mass transfer analogy is presented for a system having two evaporating compounds with a fixed value of air flow and verified by measuring and comparing mass transfer coefficients for distilled water with air flow velocities of 0.2 - 0.9 mls. An illustrative example of the use of the theory for industrial ventilation is presented.     

What makes segmentation good? A case study in boreal forest habitat mapping

Segmentation goodness evaluation is a set of approaches meant for deciding which segmentation is good. In this study, we tested different supervised segmentation evaluation measures and visual interpretation in the case of boreal forest habitat mapping in Southern Finland. The data used were WorldView-2 satellite imagery, a lidar digital elevation model (DEM), and a canopy height model (CHM) in 2 m resolution. The segmentation methods tested were the fractal net evolution approach (FNEA) and IDRISI watershed segmentation. Overall, 252 different segmentation methods, layers, and parameter combinations were tested. We also used eight different habitat delineations as reference polygons against which 252 different segmentations were tested. The ranking order of segmentations depended on the chosen supervised evaluation measure; hence, no single segmentation could be ranked as the best. In visual interpretation among the several different segmentations that we found rather good, we selected only one as the best. In the literature, it has been noted that better segmentation leads to higher classification accuracy. We tested this argument by classifying 12 of our segmentations with the random forest classifier. It was found out that there is no straightforward answer to the argument, since the definition of good segmentation is inconsistent. The highest classification accuracy (0.72) was obtained with segmentation that was regarded as one of the best in visual interpretation. However, almost similarly high classification accuracies were obtained with other segmentations. We conclude that one has to decide what one wants from segmentation and use segmentation evaluation measures with care.     

Techniques for biased data distributions and variable classification with neural networks applied to otoneurological data

It is frequently useful and advantageous to investigate not only the classification efficacy of neural networks, but also the reasons for misclassification and relations between input variables and output classes. We have developed novel techniques to disentangle these dilemmas: a network structure and learning strategy for biased output class distributions, a method to measure the classification information incorporated in variables and variable groups, and methods to express properties learned by a network from its structure. We tested these techniques with otoneurological data from the conjunction with vertiginous diseases that we have explored in our previous neural network studies.     

Distinct Fatty Acid Compositions of HDL Phospholipids Are Characteristic of Metabolic Syndrome and Premature Coronary Heart Disease—Family Study

HDL particles can be structurally modified in atherosclerotic disorders associated with low HDL cholesterol level (HDL-C). We studied whether the lipidome of the main phosphatidylcholine (PC), lysophosphatidylcholine (LPC) and sphingomyelin (SM) species of HDL2 and HDL3 subfractions is associated with premature coronary heart disease (CHD) or metabolic syndrome (MetS) in families where common low HDL-C predisposes to premature CHD. The lipidome was analyzed by LC-MS. Lysophosphatidylcholines were depleted of linoleic acid relative to more saturated and shorter-chained acids containing species in MetS compared with non-affected subjects: the ratio of palmitic to linoleic acid was elevated by more than 30%. A minor PC (16:0/16:1) was elevated (28–40%) in MetS. The contents of oleic acid containing PCs were elevated relative to linoleic acid containing PCs in MetS; the ratio of PC (16:0/18:1) to PC (16:0/18:2) was elevated by 11–16%. Certain PC and SM ratios, e.g., PC (18:0/20:3) to PC (16:0/18:2) and a minor SM 36:2 to an abundant SM 34:1, were higher (11–36%) in MetS and CHD. The fatty acid composition of certain LPCs and PCs displayed a characteristic pattern in MetS, enriched with palmitic, palmitoleic or oleic acids relative to linoleic acid. Certain PC and SM ratios related consistently to CHD and MetS.     

Entropy analysis of wet-surface cooling system for air flow

A wet-surface heat-exchanger, where the effluent air is moistened, is analysed according to a thermodynamic theory and data of experimental tests. An entropy generation function, which takes into account the changes of temperature and humidity of air, is derived. The analyses show that it is thermodynamically possible, without any cooling machine, to achieve extremely large temperature drops. With certain parameters the system results in a maximum rate of entropy generation which is used to analyse differences between two different methods of spraying the moistening water. Approximal limits for the efficient working fluid mass flow value are also given. © 1998 John Wiley & Sons, Ltd.     

Effect of sodium citrate, carboxymethyl cellulose and carrageenan levels on quality characteristics of low-salt and low-fat bologna type sausages

Quality characteristics of low-salt bologna-type sausage manufactured with sodium citrate (NAC), carboxymethyl cellulose (CMC) and carrageenan (CAR) were examined. Three levels of salt, NAC, CMC and CAR, and two levels of fat were used. Batter and sausage pH values were measured and the frying loss of sausages was analysed by frying slices in an electric grill. Firmness, juiciness, saltiness and flavour intensity of the sausages were sensorically evaluated. Altogether 20 separate sausage batches were prepared. In low-salt sausages containing less than 1.4% NaCl, the use of NAC, CAR and CMC decreased frying loss and increased saltiness. NAC and CAR also increased flavour intensity, but CMC did not. Furthermore, NAC, CAR and CMC increased the firmness of the low-salt sausage, while only NAC increased juiciness when the NaCl content was below 1.4%. NAC increases, however, the sodium content of the product. Therefore, it can be concluded that in low-salt sausages no additive alone is suitable. A mixture of NAC and CAR appears to be the best combination.     

Characterization of etching procedure in preparation of CdTe solar cells

An etching procedure for forming a low resistance contact to polycrystalline CdTe thin films in CdS/CdTe solar cells was studied. The etching solution used was a mixture of HNO₃, H₃PO₄ and H₂O. X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS) and electric measurements revealed that the etching results in a formation of crystalline tellurium on the film surface, thereby increasing substantially the conductivity of the surface layer. The total process was found to consist of three steps: (i) immediately after an immersion into the etching solution there was a certain induction period with no discernible changes, (ii) a subsequent reaction step during which poorly crystallized elemental tellurium was formed, gaseous byproducts liberated and the surface changed its colour, and (iii) after taking out of the etching solution the tellurium crystallized causing a strong decrease in the sheet resistance. In situ XRD and electric measurements were carried out to follow the third step. The chemical aspects of the three steps as well as their contributions to the reproducibility and control of the overall etching procedure have been considered.     

Improvement of UV-moulding accuracy by heat and solvent assisted process

A micro-optics replication process with UV-curable liquid pre-polymers is considered. Filling of the master structure is improved by controlling the viscosity of the pre-polymer by heat during the process. A novel process step, solvent-assisted filling, is introduced to avoid the harmful effect of the residual trapped air; a pyramidal retro-reflector structure with the face width of 400 μm is used as an example. Complete filling can be achieved without vacuum assisted replication or without application of compression force in the mould. Material studies showed no signs of chemical changes, solvent inclusion in the replicated structure, or a change of the optical properties of the material during the process. The replication fidelity is compared with conventional UV-moulding and commercial UV-NIL replication. The new heat and solvent assisted replication technique allows the use of high-viscosity pre-polymers with suitable material properties if the process temperature window is optimized.     

A DLL clock generator for a high speed A/D-converter with 1 ps jitter and skew calibrator with 1 ps precision in 0.35 μm CMOS

This paper presents a clock generator circuit for a high-speed analog-to-digital converter (ADC). A time-interleaved ADC requires accurate clocking for the converter fingers. The target ADC has 12 interleaved fingers each running at a speed of 166 MS/s, which corresponds to an equivalent sampling frequency of 2 GS/s. A delay-locked loop (DLL) based clock generator has been proposed to provide multiple clock signals for the converter. The DLL clock generator has been implemented with a 0.35 μm SiGe BiCMOS process (only MOS-transistor were used in DLL) by Austria Micro Systems and it occupies a 0.6 mm² silicon area. The measured jitter of the DLL is around 1 ps and the delay between phases can be adjusted using 1 ps precision.