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Cavity Structure (cavity + structure)
Selected AbstractsSelf-Assembled Silica Photonic Crystal as a Liquid-Crystal Alignment Layer and its Electro-optic Applications in Fabry,Perot Cavity Structures,ADVANCED MATERIALS, Issue 19 2004Y. Ha Microgrooves on self-assembled photonic-crystal (PC) films align liquid crystals (LCs) without any additional rubbing or surface treatment. Nematic (see Figure and inside cover) or twisted-nematic LCs can be formed, depending on the relative orientation of the microgrooved films. A LC Fabry,Perot (FP) cavity was fabricated using these PC films, and electro-optic tuning of FP cavity modes is demonstrated. [source] Controllable Synthesis of Cu2O Microcrystals via a Complexant-Assisted Synthetic RouteEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2010Wanqun Zhang Abstract A novel method using Cu(AC)2·H2O and dimethylglyoxime as reagents has been successfully developed for the controllable synthesis of Cu2O microcrystals with distinctive morphologies, including porous hollow microspheres, octahedral microcages, and microcrystals with truncated corners and edges and octahedral microcrystals. These structures can be fine-tuned by varying reaction temperature, reaction time, and concentration. The products were characterized by X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectra, and UV/Vis diffuse reflectance spectra. This is the first report of the preparation of the novel microcage structure of Cu2O through a simple solution-based route. By investigating the intermediate products which resemble the final crystal structures, a possible growth mechanism is proposed. Moreover, the investigations showed that the various 3D architectures of the as-made products exhibit different abilities to catalytically degrade rhodamine-B. Our work shows that octahedral Cu2O crystals with entirely {111} faces are photocatalytically more active than octahedral microcrystals with truncated corners and edges, suggesting the {111} faces of Cu2O nanostructures are catalytically more active than the {100} and {110} faces. Due to dual effect of the cavity structure and the {111} surfaces, the octahedral microcages with truncated corners and edges exhibit a higher extent of the photodecomposition reaction. As a result of very slow photocorrosion rate of the Cu2O microcrystal, it is expected that these microcrystals with different surfaces may find more applications in photocatalysis. [source] Optimization of metamaterial based subwavelength cavities for ultracompact directive antennasMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2006A. Ourir Abstract Artificial magnetic conductors (AMC) are proposed for the fabrication of subwavelength cavities in the microstrip technology. These metamaterials can simultaneously present a low phase value at reflection and a high impedance for normal incident waves over a wide frequency band. Planar cavities using AMC-based reflectors are applicable to the design of ultracompact directive antennas. An optimized cavity structure is presently shown to provide a significant enhancement of the gain and directivity of a microstrip antenna near 10 GHz. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2573,2577, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21996 [source] Untersuchung der thermisch-hygrischen Eigenschaften von Ziegeln mit Hohlraumfüllung aus RecyclingmaterialBAUPHYSIK, Issue 1 2004Azra Korjenic Dipl.-Ing. In dem Forschungsprojekt wurde untersucht, ob Ziegel mit einfacher Hohlraumstruktur durch Verwendung einer wärmedämmenden Hohlraumfüllung einen höheren Wärmedurchlaßwiderstand haben. Als Dämmstoff wurde ein Recyclingdämmaterial aus Reststoffen aus der Produktion von Polystyrolplatten sowie Holzbauteilen, die mittels Zementleim zu einem Gemisch verarbeitet wurden, verwendet. Es wurde der Einfluß von Anordnung und Stärke der Dämmschicht sowie von Lage und Geometrie der Hohlräume des Ziegelbausteines auf die thermisch-hygrischen Zustände untersucht. Für die Untersuchung der thermischen Eigenschaften und der Ermittlung der Wärmedurchgangskoeffizienten wurde das Programm THERM verwendet, das den Wärmetransport durch Wärmeleitung im Ziegelscherben und die Transportmechanismen Wärmeleitung, Konvektion und Strahlung in den luftgefüllten Hohlräumen berücksichtigt. Zur Untersuchung des Feuchtigkeitstransports in den Ziegelsteinen wurde das Programmpaket WUFI 2D verwendet. Die Untersuchungen haben gezeigt, daß die so strukturierten Ziegel-Verbundsteine einen etwa doppelt so hohen Dämmwert haben, wie der ursprüngliche Ziegelstein. Die hygrischen Zustände können im Ziegel teilweise über 80 % Luftfeuchtigkeit betragen. Diese Belastung wird als unkritisch eingeschätzt, weil die Holzpartikel mit Zementschlämme umhüllt sind. Investigation on the thermal-hygral behaniour of bricks with canity filling by recycling meterials. In the investigation project was examined whether bricks with simple cavity structure have a higher heat resistance by use of a heat insulation material filling in the cavities. The insulation material is a recycled product made of polystyrene and wood covered and bonded with cement. The influence of the configuration and thickness of the perforated bricks with vertical perforations and the geometry of the cavities of the brick on the thermal moisture states was evaluated. For investigation of the thermal resistance and the heat transmission coefficients were used the simulation program THERM, that considered the heat transportation through conduction in the brick fragments and the transport mechanisms conduction, convection and radiation in the airfilled cavities. The software package WUFI 2D was employed for the investigation of moisture transfer in the bricks. The investigations showed that the composite brick insulation stone has a thermal resistance twice as high as the initial brick. The moisture states can be partially in the brick more than 80 % humidity. This load is estimated as uncritical because the wooden particles are covered with cement slime. [source] Fabrication of Precise Fluidic Structures in LTCCINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 1 2009Fred Barlow A number of emerging applications of low-temperature co-fired ceramic (LTCC) require embedded fluidic structure within the co-fired ceramic and or precise external dimensional tolerances. These structures enable the control of fluids for cooling, sensing, and biomedical applications, and variations in their geometry from the design can have a significant impact on the overall performance of the devices. One example of this type of application is a multilayer cooler developed recently by the authors for cooling laser diode bars. In many laser systems, laser diodes are the primary emitters, or assemblies of these diode bars are used to pump traditional laser crystals such as Nd:YLF. Assemblies of these diodes require large amounts of electrical current for proper operation, and the device operating temperature must be carefully controlled in order to avoid a shift in the output wavelength. These diodes are packaged into water-cooled assemblies and by their nature dissipate enormous amounts of heat, with waste heat fluxes on the order of 2000 W/cm2. The traditional solution to this problem has been the development of copper multilayer coolers. Assemblies of laser diodes are then formed by stacking these diode bars and coolers. Several problems exist with this approach including the erosion of the copper coolers by the coolant, a requirement for the use of deionized water within the system, and a significant CTE mismatch between the diode bar and the metal cooler. Diodes are bonded to these metal structures and liquid coolant is circulated through the metal layers in order to cool the diode bar. In contrast, the coolers developed by the authors utilize fluid channels and jets formed within LTCC as well as embedded cavity structures to control the flow of a high-velocity liquid and actively cool the laser diode bars mounted on the surface of the LTCC., The dimensional tolerances of these cooler assemblies and complex shapes that are used to control the fluid can have a significant impact on the overall performance of the laser system. This paper describes the fabrication process used to create the precise channel and jet structures used in these LTCC-based coolers, as well as some of the challenges associated with these processes. [source] 60 GHz SoC/SoP radio system for high data-rate transmissionMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2010K. C. Eun Abstract We present the 60 GHz CMOS and system-on-package (SoP) research activities in Korea Advanced Institute of Science and Technology for high data-rate and short-range wireless communication. A low-power single-chip resonant frequency CMOS receiver for 60 GHz mobile terminals consists of four-stage current reuse LNA, resistive mixer, Ka-band low-phase noise VCO, high-suppression frequency doubler, and two-stage current reuse drive amplifiers. The receiver conversion gain and input P1dB are ,9.5 dB and ,12.5 dBm, respectively, with a size of 2.67 × 0.75 mm2 and power consumption of 21.9 mW. The integration and communication tests of a transmitter/receiver (Tx/Rx) radio have been demonstrated at a data rate of 3 Gbps for short-range transmission and with a communication distance of over 3.5 m at 650 Mbps data rate. The design and fabrication of mmW subcircuits, such as low-loss transmission lines and transitions with noble air cavity structures, a high-Q resonator using zigzagged dual-row via posts and a ,/4 short stub, and the monolithic integration of band-pass filter and antennas, have been performed for low-temperature cofired ceramic SoP integration with a size of 37 × 11 mm2 for the whole Tx or Rx radio. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 667,673, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25024 [source] Distribution of olfactory epithelium in the primate nasal cavity: Are microsmia and macrosmia valid morphological concepts?THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2004Timothy D. Smith Abstract The terms "microsmatic" and "macrosmatic" are used to compare species with greater versus lesser olfactory capabilities, such as carnivores compared to certain primates. These categories have been morphologically defined based on the size of olfactory bulb and surface area of olfactory epithelium in the nasal fossa. The present study examines assumptions regarding the morphological relationship of bony elements to the olfactory mucosa, the utility of olfactory epithelial surface area as a comparative measurement, and the utility of the microsmatic concept. We examined the distribution of olfactory neuroepithelium (OE) across the anteroposterior length of the nasal fossa (from the first completely enclosed cross-section of the nasal fossa to the choanae) in the microsmatic marmoset (Callithrix jacchus) compared to four species of nocturnal strepsirrhines (Otolemur crassicaudatus, O. garnetti, Microcebus murinus, and Cheirogaleus medius). Adults of all species were examined and infant C. jacchus, O. crassicaudatus, M. murinus, and C. medius were also examined. All specimens were serially sectioned in the coronal plane and prepared for light microscopic study. Distribution of OE across all the turbinals, nasal septal surfaces, and accessory spaces of the nasal chamber was recorded for each specimen. The right nasal fossae of one adult C. jacchus and one neonatal M. murinus were also three-dimensionally reconstructed using Scion Image software to reveal OE distribution. Findings showed OE to be distributed relatively more anteriorly in adult C. jacchus compared to strepsirrhines. It was also distributed more anteriorly along the nasal septal walls and recesses in neonates than adults. Our findings also showed that OE surface area was not a reliable proxy for receptor neuron numbers due to differing OE thickness among species. Such results indicate that nasal cavity morphology must be carefully reconsidered regarding traditional functional roles (olfaction versus air conditioning) assigned to various nasal cavity structures. At present, the microsmatic concept itself lacks a basis in nasal chamber morphology, since OE may have varying patterns of distribution among different primates. © 2004 Wiley-Liss, Inc. [source] | |||||||||||||