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81.
82.
Calcium oxide and calcium hafnium oxide thin films were grown by atomic layer deposition on borosilicate glass and silicon substrates in the temperature range of 205–300 °C. The calcium oxide films were grown from novel calcium cyclopentadienyl precursor and water. Calcium oxide films possessed refractive index 1.75–1.80. Calcium oxide films grown without Al2O3 capping layer occurred hygroscopic and converted to Ca(OH)2 after exposure to air. As-deposited CaO films were (200)-oriented. CaO covered with Al2O3 capping layers contained relatively low amounts of hydrogen and re-oriented into (111) direction upon annealing at 900 °C. In order to examine the application of CaO in high-permittivity dielectric layers, mixtures of Ca and Hf oxides were grown by alternate CaO and HfO2 growth cycles at 230 and 300 °C. HfCl4 was used as a hafnium precursor. When grown at 230 °C, the films were amorphous with equal amounts of Ca and Hf constituents (15 at.%). These films crystallized upon annealing at 750 °C, showing X-ray diffraction peaks characteristic of hafnium-rich phases such as Ca2Hf7O16 or Ca6Hf19O44. At 300 °C, the relative Ca content remained below 8 at.%. The crystallized phase well matched with rhombohedral Ca2Hf7O16. The dielectric films grown on Si(100) substrates possessed effective permittivity values in the range of 12.8–14.2.  相似文献   
83.
84.
Two integrated direct I/Q modulators suitable for directupconversion with an output frequency of 950 MHz and baseband frequencies of60 to 500 kHz are fabricated in a 1.2 µm and 0.8 µm BiCMOSprocess, respectively, and their performance under various operatingconditions is discussed. The modulators use different phase shiftertopologies, one of which is based on digital CML latches and the other ondifferential pairs with resistive and capacitive emitter degeneration. Bothcircuits are operated using a single 5 V supply and they consume 50 mA or115 mA depending on the topology. The main properties of the CML modulatorare, for example, an output power of –11 ± 0.5 dBm at 100 MHzand –15 ± 2.25 dBm at 950 MHz over the temperature range of–10 to +85°C, LO suppression of 38 dBc and image rejection of41 dBc.  相似文献   
85.
A comprehensive experimental study was carried out to replicate sub‐micron features using the injection molding technique. For the experiments, five different plastic materials were selected according to their flow properties. The materials were polycarbonate (PC), styrene‐butadiene block copolymer (SBS), impact modified poly(methyl methacrylate), methyl methacrylate‐acrylonitrile‐butadiene‐styrene polymer (MABS), and cyclic olefin copolymer (COC). Nanofeatures down to 200‐nm line width and with aspect ratios (aspect ratio = depth/width) of 1:1 could be replicated. In all selected materials, the greatest differences between the materials emerged when the aspect ratio increased to 2:1. The most favorable results were obtained with the use of high flow polycarbonate as the molding material. The best replication results were achieved when melt and mold temperatures were higher than normal values.  相似文献   
86.
ZrO2 films of thicknesses varied in the range of 3–30 nm were atomic layer deposited from ZrI4 and H2O–H2O2 on p-Si(100) substrates. The effects of film thickness and deposition temperature on the structure and dielectric properties of ZrO2 were investigated. At 272 and 325 °C, the growth of ZrO2 started with the formation of the cubic polymorph and continued with the formation of the tetragonal polymorph. The ratio between the lattice parameters increased with the film thickness and growth temperature. The effective permittivity, determined from the accumulation capacitance of Hg/ZrO2/Si capacitors, increased with the film thickness, reaching 15–17 in 25-nm-thick films. The permittivity decreased with the increasing growth temperature. The hysteresis of the capacitance–voltage curves was the narrowest for the films deposited at 325 °C, and increased towards both lower and higher deposition temperatures.  相似文献   
87.
The need for higher data rates is ever rising as wireless communications standards move from the third to the fourth generation. Turbo-Codes are the prevalent channel codes for wireless systems due to their excellent forward error correction capability. So far research has mainly focused on components of high throughput Turbo-Decoders. In this paper we explore the Turbo-Decoder design space anew, both under system design and deep-submicron implementation aspects. Our approach incorporates all levels of design, from I/O behavior down to floorplaning taking deep-submicron effects into account. Its scalability allows to derive optimized architectures tailored to the given throughput and target technology. We present results for 3GPP compliant Turbo-Decoders beyond 100 Mbit/s synthesized on a 0.18 μm standard cell library.  相似文献   
88.
This work presents a new multiscale technique to investigate advancing cracks in three dimensional space. This fully adaptive multiscale technique is designed to take into account cracks of different length scales efficiently, by enabling fine scale domains locally in regions of interest, i.e. where stress concentrations and high stress gradients occur. Due to crack propagation, these regions change during the simulation process. Cracks are modeled using the extended finite element method, such that an accurate and powerful numerical tool is achieved. Restricting ourselves to linear elastic fracture mechanics, the $J$ -integral yields an accurate solution of the stress intensity factors, and with the criterion of maximum hoop stress, a precise direction of growth. If necessary, the on the finest scale computed crack surface is finally transferred to the corresponding scale. In a final step, the model is applied to a quadrature point of a gas turbine blade, to compute crack growth on the microscale of a real structure.  相似文献   
89.
A program system for fracture assessment of nuclear power plant structures has been developed. The system consists of an easy-to-use program for engineering analysis and an automated finite element (FE) program system for more accurate analysis with solid three-dimensional (3D) models. The VTTSIF (SIF stress intensity factor) program for engineering fracture assessment applies either the weight function method or superposition method in calculating the stress intensity factor, and the fatigue crack growth analysis is based on the Paris equation. The structural geometry cases of the VTTSIF program are organized in an extendable subroutine database. The generation of a 3D FE model of a cracked structure is automated by the ACR program (automatic finite element model generation for part through cracks). The FE analyses are created with generally accepted commercial programs, and the virtual crack extension method (VCE) is used for fracture parameter evaluation by the VTTVIRT postprocessor program (program for J-integral evaluation using virtual crack extension method). The several test cases have demonstrated that the accuracy of the present system is satisfactory for practical applications.  相似文献   
90.
Although Finland's forest resources have been utilized intensively, the size of the total volume of the growing stock has increased since the mid-1960s, and hence increasing amounts of carbon have been sequestered by forests. The net sequestration by forests has also been substantial when compared with the CO2 emissions resulting from energy generation and consumption based on fossil fuels and peat. It is also important, from the point of view of mitigating the effects of climate change, to assess how the sequestration capacity of forests may change under changing climatic conditions. This paper presents the results of a study assessing the development of the forest and wood-product carbon budget for Finland, based on regionally measured data, detailed dynamic models, and recent predictions concerning the changing climate. At the starting point for the simulation (1990), nearly 90% of the forest sector's carbon storage was found in the forest. Regular management transferred carbon from forests to wood products. Under the current climatic conditions, the simulated forest carbon storage increased 45% by the year 2100, and the wood-product storage by 320%, as a consequence of continuous production. Under changing climate conditions, the forest carbon storage increased, but started to decline when the temperature increase exceeded 2.5°C within 40 years.  相似文献   
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