Gravure printed flexible organic photovoltaic modules

In this letter, organic solar cell modules based on poly-3-hexylthiophene (P3HT) and [6.6]-phenyl-C61-butyric acid methyl ester (PCBM) blend films with a module active area of 15.45 cm² prepared by roll-to-roll (R2R) compatible gravure printing method are demonstrated. The gravure printed organic photovoltaic modules consist of eight serially connected solar cells in same substrate. Indium-tin-oxide (ITO) is patterned by screen printable etching paste. Hole injection layer and active layer are prepared by gravure printing method. All processing steps excluding cathode evaporation are performed in air. Electrical measurements are done to modules consisting of 5-8 serially connected solar cells. The photovoltaic modules comprising 5, 7 and 8 serially connected cells exhibit an active area power conversion efficiency of 1.92%, 1.79% and 1.68%, respectively (Oriel Sol3A Class AAA, AM1.5G, 100 mW cm⁻²).     

A Double Sampling 8-Bit, 50 MS/s, 32 mW Pipeline Converter with +6 dB Overdrive Headroom

An 8-bit, 50 MS/s pipeline converter is presented with peak SNR and SFDR of 43.1 dB and 52.5 dB, corresponding to effective number of bits of 6.9. The circuit is implemented in a 0.35 m CMOS process, the core area is 0.36 mm² and its analog and digital current consumptions (including I/O buffers) are 6.2 mA and 4.5 mA from a 3 V supply. The low power consumption is achieved by using two banks of sampling capacitors (double sampling) and a mixed architecture giving 1+1+1+2+3 bits per stage. The mixed architecture means that a full ninth bit cannot be coded, but instead it is a employed as an almost 6 dB overdrive input range. The maximum allowable comparator errors in different architectures are calculated and the benefits of excess redundancy are discussed.     

Large enhancement of fluorescence efficiency from CdSe/ZnS quantum dots induced by resonant coupling to spatially controlled surface plasmons

Nanoengineered fluorescent response is reported from semiconductor core-shell (CdSe/ZnS) quantum dots in proximity to the surface plasmon polariton field of periodic Ag nanoparticle arrays. Tuning the surface plasmon polariton resonance to the quantum dot exciton emission band results in an enhancement of up to approximately 50-fold in the overall fluorescence efficiency, in a design where each Ag nanoparticle is interconnected by a continuous Ag thin film. Propagating modes of surface plasmon resonances have a direct impact on the fluorescence enhancement.     

Chemical composition, mass size distribution and source analysis of long-range transported wildfire smokes in Helsinki

Special episodes of long-range transported particulate (PM) air pollution were investigated in a one-month field campaign at an urban background site in Helsinki, Finland. A total of nine size-segregated PM samplings of 3- or 4-day duration were made between August 23 and September 23, 2002. During this warm and unusually dry period there were two (labelled P2 and P5) sampling periods when the PM2.5 mass concentration increased remarkably. According to the hourly-measured PM data and backward air mass trajectories, P2 (Aug 23-26) represented a single, 64-h episode of long-range transported aerosol, whereas P5 (Sept 5-9) was a mixture of two 16- and 14-h episodes and usual seasonal air quality. The large chemical data set, based on analyses made by ion chromatography, inductively coupled plasma mass spectrometry, X-ray fluorescence analysis and smoke stain reflectometry, demonstrated that the PM2.5 mass concentrations of biomass signatures (i.e. levoglucosan, oxalate and potassium) and of some other compounds associated with biomass combustion (succinate and malonate) increased remarkably in P2. Crustal elements (Fe, Al, Ca and Si) and unidentified matter, presumably consisting to a large extent of organic material, were also increased in P2. The PM2.5 composition in P5 was different from that in P2, as the inorganic secondary aerosols (NO3-, SO4(2-), NH4+) and many metals reached their highest concentration in this period. The water-soluble fraction of potassium, lead and manganese increased in both P2 and P5. Mass size distributions (0.035-10 microm) showed that a large accumulation mode mainly caused the episodically increased PM2.5 concentrations. An interesting observation was that the episodes had no obvious impact on the Aitken mode. Finally, the strongly increased concentrations of biomass signatures in accumulation mode proved that the episode in P2 was due to long-range transported biomass combustion aerosol.     

A Broadband Double-Conversion RF Tuner

A prototype design of upconverter and downconverter units for a double-conversion cable-modem RF tuner are presented. The upconverter upconverts a channel from 47–862 MHz input band to around 1575 MHz intermediate frequency. The image-reject downconverter shifts the channel to 36.125 MHz (EU) or to 43.75 MHz (US). The upconverter includes a variable-gain low-noise amplifier, a double-balanced mixer, a three-stage VCO bank for LO generation and a divide-by-two circuit for driving an external PLL. The downconverter includes a LNA, image-reject mixers in Hartley configuration, a 3-stage polyphase filter, an IF-amplifier and a SAW driver. For the second LO generation the circuit includes a 6-GHz on-chip VCO, a divide-by-four circuit for quadrature LO and a divide-by-16 for feeding an external PLL. Signal reversal switching in the LO buffer can be used for the selection of LSB/USB injection. All building blocks are presented in this paper and experimental results are given from the upconverter, downconverter, and RF tuner demonstrator including SAW filters with center frequencies at 1575 and 44 MHz. The circuits are fabricated in a 0.9- m SiGe bipolar process.Kari Stadius received the M.Sc. degree in electrical engineering in 1994 and the Licentiate of Technology degree in 1997, both from Helsinki University of Technology, where he is currently working as a research scientist. His research interests include the design and analysis of RF transceiver blocks with special emphasis on RF oscillators and modelling of passive components.Arto Malinen was born in Savonlinna, Finland, in 1978. He received the M.Sc. degree in electrical engineering from the Helsinki University of Technology (HUT), Finland, in 2003, where he is currently working towards the Ph.D. degree. He is a research engineer with the Electronic Circuit Design Laboratory, HUT. His main research interests are in RF IC design, including low-noise amplifiers and mixers.Petri S. Järviö was born in Kitee on December 10, 1975. He received the M.Sc (EE) degree in 2001 from the Helsinki University of Technology. From 1999 to 2001 he worked as a research assistant at the Electronic Circuit Design Laboratory in Helsinki University of Technology. Nowadays he works at Finnish Defence Forces Technical Research Centre, Electronics and Information Technology Division where his research area is Radio frequency sensors.Kari A.I. Halonen was born in Helsinki, Finland, in 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. From 1982 to 1984 he was employed as assistant at Helsinki University of Technology and as research assistant at the Technical Research Centre of Finland. From 1984 to 1987 he was research assistant at the E.S.A.T. Laboratory of the Katholieke Universiteit Leuven, enjoying also a temporary grant of the Academy of Finland. Since 1988 he has been with the Electronic Circuit Design Laboratory, Helsinki University of Technology, as senior assistant (1988–1990), and the director of the Integrated Circuit Design Unit of the Microelectronics Centre (1990–1993). He was on leave of absence the academic year 1992/93, acting as R{&}D manager in Fincitec Inc., Finland. From 1993 to 1996 he has been an associate professor, and since 1997 a full professor at the Faculty of the Electrical Engineering and Telecommunications, Helsinki University of Technology. He specializes in CMOS and BiCMOS analog integrated circuits, particularly for telecommunication applications. He is author or co-author of a hundred international and national conference and journal publications on analog integrated circuits.     

On sentential forms of context-free grammars

Summary There is no algorithm for deciding whether two linear context-free grammars generate the same sentential forms. The equivalence problem for propagatingOL-systems is undecidable. The finiteness problem forOL-systems is decidable.SF-languages, i.e., languages which equal the set of sentential forms of a context-free grammar, possess some of the properties of context-free languages but their family is not closed under any of the ordinary operations.     

Experiences in developing mobile applications using the Apricot Agent Platform

The trend of increasing mobile services has set a new challenge for service providers: how to develop more advanced and user-friendly, context-aware and personalized mobile services for the users. Apricot Agent Platform is an agent-based software platform designed for developing context-aware and personalized mobile services. Apricot Agent Platform supports the development of user-friendly mobile services by providing tools for combining various mobile and Internet-based services. Apricot agent architecture consists of an agent platform, agents and agent containers. For the developers of mobile services, it provides built-in functionality and communication mechanism. Furthermore, this paper describes four demonstrators that are built up on the Apricot Agent Platform to evaluate the usability and efficiency of the platform in the processes of building mobile services. The outcome of the evaluation indicates relatively promising results and the further target for development is revealed.     

Air Entrainment During Flame Aerosol Synthesis of Nanoparticles

Enclosed flames typically produce substantially larger particles than open flames under identical reactant flows and composition. The enclosure hinders air entrainment to the flame and reduces heat losses by radiation and convection, facilitating particle coagulation and coalescence. Here the effect of natural air entrainment on flame aerosol synthesis is investigated by lifting off the enclosing tube from the burner surface and utilizing tracer gas (Ne) analysis after calibration with forced air entrainment. That way the effect of air entrainment on product primary particle diameter and mobility size distribution dynamics is investigated by microscopy, scanning mobility particle sizing, and N₂ adsorption, while temperature is measured by Fourier-transform infrared spectroscopy. So air entrainment during flame spray pyrolysis is examined here for its versatility in scalable manufacture of an array of material compositions, while copper oxide (CuO) is used for its electro-chemical applications (e.g., battery electrodes). It is shown that natural air entrainment facilitates rapid gas-to-particle conversion and high process yields by minimizing vortex recirculation and particle deposition on the enclosing tube walls and burner surface. For example, the average primary particle diameter of CuO can be controlled from 42 to 10 nm and the yield from 40 to 90% by gradually lifting off the enclosing tube, resulting in up to 250 L/min natural air entrainment at the present CuO synthesis conditions.

Copyright 2014 American Association for Aerosol Research