冲击干燥提高效率和产能

对美卓造纸机械的冲击干燥装置进行了简述。将冲击干燥与传统干燥的蒸发效率进行了比较,对比结果表明了冲击干燥装置的优越性。     

Simplifying the role of signals in tile self-assembly

Natural Computing - Sending signals through DNA-based structures is one of the methods used to enhance the capabilities of DNA self-assembly systems. Signal Tile Assembly Models at temperature one,...     

Quantitative analysis of sperm rheotaxis using a microfluidic device

Quite puzzling issue in biology is how sperm cells are selected naturally where human sperm has to maintain a correct swimming behavior during the various stages of reproduction process. In nature, sperm has to compete a long journey from cervix to oocyte to stand a chance for fertilization. Although various guidance mechanisms such as chemical and thermal gradients are proposed previously, these mechanisms may only be relevant as sperm reaches very close to the oocyte. Rheotaxis, a phenomenon where sperm cells swim against the flow direction, is possibly the long-range sperm guidance mechanism for successful fertilization. A little is known quantitatively about how flow shear effects may help guide human sperm cells over long distances. Here, we have developed microfluidic devices to quantitatively investigate sperm rheotaxis at various physiological flow conditions. We observed that at certain flow rates sperm actively orient and swim against the flow. Sperm that exhibit positive rheotaxis show better motility and velocity than the control (no-flow condition), however, rheotaxis does not select sperm based on hyaluronic acid (HA) binding potential and morphology. Morphology and HA binding potential may not be a significant factor in sperm transport in natural sperm selection.     

Characterization of wear surfaces in dry sliding of steel and alumina on hydrogenated and hydrogen-free carbon films

Hydrogenated amorphous carbon coatings were deposited by r.f. plasma and hydrogen-free carbon films in pulsed arc discharge on stainless steel substrates. The coatings were characterized and evaluated in tribological tests. Pin-on-disc tests were used over a wide range of test parameters: normal load, 5–40 N; sliding velocity, 0.1–3.0 m s⁻¹. The wear of both coatings was of the same order of magnitude (0.7 × 10⁻³−5.1 × 10⁻³ mm³). However, the wear of the counterface was one order of magnitude higher for the hydrogenfree carbon coatings. Increasing the normal load generally caused an increase in coating wear and in most cases also an increase in counterface wear. When the steel pin was sliding against the hydrogenated carbon coating with a high sliding velocity and load, a rather thick tribofilm was formed on the pin wear surface, lowering the coefficient of friction and reducing the pin wear. The tribofilm formed on the alumina pin sliding against the hydrogenated carbon film also seemed to reduce the friction coefficient but could not prevent the pin wear. A tribofilm was also formed on the pin wear surface when the hydrogen-free carbon coating was sliding against the steel and alumina pins, but the layer was not able to protect the pins. The tribofilm did, however, lower the coefficient of friction, which was rather insensitive to the different test parameters used. According to secondary ion mass spectroscopy analyses, material transfer of the pin was detected on the disc (coated) wear surfaces. The tribofilms formed on the pin wear surfaces consisted of pin material, hydrogen, oxygen, and carbon.     

A 0.18$$\upmu$$m CMOS voltage multiplier arrangement for RF energy harvesting

This work presents a two-stage voltage multiplier (VM) useful in RF energy harvesting based applications. The proposed circuit is based on the conventional differential drive rectifier, in which the input RF signal has been level shifted using a simple arrangement. This signal is then used to drive the next stage, which has been formed by using gate cross-coupled transistors. As a result, the load driving capability of the proposed architecture increases. The load in this work has been emulated in terms of a parallel RC circuit. The architecture has been implemented using standard 0.18 \(\mu\)m CMOS technology. The measurements of the two-stage conventional VM (CVM) and proposed VM circuits were performed at ISM frequencies 13.56, 433, 915 MHz and 2.4 GHz for R\(_L\) of values 1, 5, 10, 3 and 100 K\(\Omega\) with a fixed value of C\(_L\) equal to 20 pF. The performance evaluation has been done in terms of the power conversion efficiency (PCE) and average output DC voltage. The measured results show an improvement in PCE of 5% (minimum) for 13.56, 433 and 915 MHz frequencies, and up to 2% improvement for a frequency value of 2.4 GHz at the targeted load condition of 5 K\(\Omega ||\)20 pF, when compared with the measured results of the CVM circuit.     

Underground space in land-use planning

In 1988, the Finnish Ministry of the Environment appointed a committee to review existing planning systems for underground construction. In its report in spring 1990, the committee concluded that current legislation and planning procedures were unsatisfactory. In response, a study on “Underground Space in the Planning and Land Use” was launched in June 1994, and was completed in summer 1996. The study formed part of Finland's Rock Engineering 2000 programme. The study reviewed the present situation in underground planning; examined current uses of underground facilities; created a basic method for the classifying the building potential of rock areas, identified the various methods currently available for assessing the environmental impacts of underground construction on the basis of the legislation in force (EIA); to developed methods for assessing the costs to the urban community of underground space, particularly in comparison with equivalent costs of space aboveground; and drafted a proposal concerning planning of different level and permit procedures for underground space. This paper discusses each aspect of the study.     

Up-conversion mixers in a complementary 0.4 μm SiGe process

In this paper a 0.4 μm complementary SiGe process is used to fabricate up-conversion mixers for base-station applications. A current feedback mixer, and a mixer with a folded input, were designed in order to test benefits obtainable from the use of equally fast PNP- and NPN-transistors. The target was to improve linearity and to increase output compression point ( ) of the mixers. A +5 dBm output compression point @2 GHz was measured while drawing 43 mA from 5 V voltage supply. Harri Pellikka was born in Espoo, Finland, in 1980. He received the M.Sc. degree in electronics and electrical engineering from Helsinki University of Technology in 2005. He has been with Helsinki University of Technology Electronic Circuit Design Laboratory since 2003, where he works as research engineer. His research interests include the design of integrated circuits for telecommunication applications. Esa Tiiliharju was born in Rovaniemi, Finland, in 1966. He received the M.Sc. degree in information technology in 1995, and the Lic.Tech degree in electrical engineering in 1998, both from Helsinki University of Technology, Finland. He has joined the Microelectronics Laboratory in University of Turku in 2006. His research interests include the design of integrated circuits for telecommunication applications. Kari A. I. Halonen was born in Helsinki, Finland, on May 23, 1958. He received the M.Sc. degree in electrical engineering from Helsinki University of Technology, Finland, in 1982, and the Ph.D. degree in electrical engineering from the Katholieke Universiteit Leuven, in Heverlee, Belgium, in 1987. Since 1988 he has been with the Electronic Circuit Design Laboratory, Helsinki University of Technology. From 1993 he has been an associate professor, and since 1997 a full professor at the Faculty of Electrical Engineering and Telecommunications. He became the Head of Electronic Circuit Design Laboratory year 1998. From 1997 to 1999 he was an associate editor of IEEE Transactions on Circuits and Systems I. He has been a guest editor for IEEE Journal of Solid-State Circuits and the Technical Program Committee Chairman for European Solid-State Circuits Conference year 2000. He has been awarded the Beatrice Winner Award in ISSCC’02 Conference year 2002. He specializes in CMOS and BiCMOS analog integrated circuits, particularly for telecommunication applications. He is author or co-author over a hundred and fifty international and national conference and journal publications on analog integrated circuits. He has several patents on analog integrated circuits.     

Degradation of EDTA and novel complexing agents in pulp and paper mill process and waste waters by Fenton's reagent

Fenton's process was used in oxidative degradation of ethylediaminetetraacetic acid (EDTA) and novel complexing agents, namely BCA5 and BCA6, in distilled water and spiked samples of integrated pulp and paper mill waste water and ECF-pulp bleaching effluent. In waste water, over 90% of EDTA was degraded within 3 min when temperature was 60 degrees C, pH 4, and molecular ratio of H2O2:Fe2+:EDTA was 70:2:1 (0.26 mM EDTA) or higher. In spiked ECF bleaching effluent up to 42% of EDTA was degraded in similar reaction conditions, still higher than published results indicate biological waste water treatment of pulp and paper mill waste water being capable of. In pH 3, EDTA proved readily degradable by Fenton's process in otherwise similar conditions. According to these results, Fenton's process could be used as a pre-treatment method for EDTA-containing bleaching effluents prior to the biological waste water treatment. In addition, BCA5 and BCA6 proved their superiority in terms of degradability also by Fenton's process in both pH 3 and 4.