Comparison of Two Integrated BiCMOS 950 MHz Direct I/Q Modulators

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.     

Replication of sub‐micron features using amorphous thermoplastics

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.     

Influence of thickness and growth temperature on the properties of zirconium oxide films grown by atomic layer deposition on silicon

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.     

A Scalable System Architecture for High-Throughput Turbo-Decoders

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.     

Hostility,driving anger,and dangerous driving: The emerging role of hemispheric preference

Background

Various studies have implicated psychosocial variables (e.g., hostility) in risk of dangerous driving and traffic accidents. However, whether these variables are related to more basic neurobiological factors, and whether such associations have implications for the modification of psychosocial risk factors in the context of driving, have not been examined in depth. This study examined the relationship between hemispheric preference (HP), hostility and self-reported dangerous driving, and the ability to affect driving anger via hemisphere activating cognitive exercises (HACE).

Methods

In Study 1, 254 Turkish students completed questionnaires of hostility, HP and driving behavior. In Study 2, we conducted a “proof of concept” experimental study, and tested effects of left, right and neutral HACE on driving anger, by exposing N = 650 Turkish students to written scenarios including either logical (left hemisphere), visuo-spatial (right hemisphere) or “mild doses” of both types of contents (control).

Results

In Study 1, left-HP was associated with higher hostility and with more dangerous driving, and hostility mediated the relationship between L-HP and reported driving behavior. In Study 2, only right-HACE led to immediate significant reductions in self-reported driving anger.

Conclusions

Left-HP is related to hostility and to dangerous driving, and it may be possible to partly reduce driving anger by right-HACE. Future studies must replicate these findings with objective measures, more enduring interventions and longer follow-ups.     

3D multiscale crack propagation using the XFEM applied to a gas turbine blade

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.     

Development of an automated fracture assessment system for nuclear structures

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.     

Potential contribution of the forest sector to carbon sequestration in Finland

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.     

Au@Hg Nanoalloy Formation Through Direct Amalgamation: Structural,Spectroscopic, and Computational Evidence for Slow Nanoscale Diffusion

Dynamic core–shell nanoparticles have received increasing attention in recent years. This paper presents a detailed study of Au–Hg nanoalloys, whose composing elements show a large difference in cohesive energy. A simple method to prepare Au@Hg particles with precise control over the composition up to 15 atom% mercury is introduced, based on reacting a citrate stabilized gold sol with elemental mercury. Transmission electron microscopy shows an increase of particle size with increasing mercury content and, together with X‐ray powder diffraction, points towards the presence of a core–shell structure with a gold core surrounded by an Au–Hg solid solution layer. The amalgamation process is described by pseudo‐zero‐order reaction kinetics, which indicates slow dissolution of mercury in water as the rate determining step, followed by fast scavenging by nanoparticles in solution. Once adsorbed at the surface, slow diffusion of Hg into the particle lattice occurs, to a depth of ca. 3 nm, independent of Hg concentration. Discrete dipole approximation calculations relate the UV–vis spectra to the microscopic details of the nanoalloy structure. Segregation energies and metal distribution in the nanoalloys were modeled by density functional theory calculations. The results indicate slow metal interdiffusion at the nanoscale, which has important implications for synthetic methods aimed at core–shell particles.     

Low-temperature atomic layer deposition of ZnO thin films: Control of crystallinity and orientation

Low-temperature atomic layer deposition (ALD) processes are intensely looked for to extend the usability of the technique to applications where sensitive substrates such as polymers or biological materials need to be coated by high-quality thin films. A preferred film orientation, on the other hand, is often required to enhance the desired film properties. Here we demonstrate that smooth, crystalline ZnO thin films can be deposited from diethylzinc and water by ALD even at room temperature. The depositions were carried out on Si(100) substrates in the temperature range from 23 to 140 °C. Highly c-axis-oriented films were realized at temperatures below ~ 80 °C. The film crystallinity could be further enhanced by post-deposition annealing under O₂ or N₂ atmosphere at 400-600 °C while keeping the original film orientation intact.