Reduced-Complexity Near-Maximum-Likelihood Detection for Decision Feedback Assisted Space-Time Equalization

A novel decision-feedback (DF) aided reduced complexity maximum likelihood (ML) space-time equalizer (STE) designed for a single-carrier system is introduced. Two different methods of incorporating DF into the recursive tree search based receiver structure are proposed for allowing detection at a moderate computational cost. Additionally, a further complexity reduction scheme is proposed, which exploits the specific characteristics of both the wide-band channel and the proposed DF-STE. In comparison to the DF-STE not benefiting from this complexity reduction, the proposed detector is capable of reducing the complexity by several orders of magnitude. More quantitatively, for the specific rank-deficient system considered, which detected the signal transmitted from four transmit antennas with the aid of two receive antennas, the complexity might be reduced by a factor of 100 at low Signal-to-noise ratios (SNRs) without noticeable performance degradation. By contrast, at higher SNRs a complexity reduction of a factor of 10 might be achieved, depending on the tolerable performance degradation.     

Insights into the In Vitro Formation of Apatite from Mg-Stabilized Amorphous Calcium Carbonate

A protein-free formation of bone-like apatite from amorphous precursors through ball-milling is reported. Mg²⁺ ions are crucial to achieve full amorphization of CaCO₃. Mg²⁺ incorporation generates defects which strongly retard a recrystallization of ball-milled Mg-doped amorphous calcium carbonate (BM-aMCC), which promotes the growth of osteoblastic and endothelial cells in simulated body fluid and has no effect on endothelial cell gene expression. Ex situ snapshots of the processes revealed the reaction mechanisms. For low Mg contents (<30%) a two phase system consisting of Mg-doped amorphous calcium carbonate (ACC) and calcite “impurities” was formed. For high (>40%) Mg²⁺ contents, BM-aMCC follows a different crystallization path via magnesian calcite and monohydrocalcite to aragonite. While pure ACC crystallizes rapidly to calcite in aqueous media, Mg-doped ACC forms in the presence of phosphate ions bone-like hydroxycarbonate apatite (dahllite), a carbonate apatite with carbonate substitution in both type A (OH⁻) and type B (PO₄³⁻) sites, which grows on calcite “impurities” via heterogeneous nucleation. This process produces an endotoxin-free material and makes BM-aMCC an excellent “ion storage buffer” that promotes cell growth by stimulating cell viability and metabolism with promising applications in the treatment of bone defects and bone degenerative diseases.     

UNICORE 6 — Recent and Future Advancements

UNICORE is a European Grid Technology with more than 10 years of history. Originating from the Supercomputing domain, the latest version UNICORE 6 has turned into a general-purpose Grid technology that follows established standards and offers a rich set of features to its users. The paper starts with an architectural insight into UNICORE 6, highlighting the workflow features, standards and the different clients. Next, the current state of advancement is presented by describing recent developments. The paper closes with an outlook on future planned developments.     

环形直线行波超声电机定子的模态分析

针对一类环形封闭式的行波型直线超声电机定子的振动模态进行了有限元与实验研究。该类电机的定子由两个半圆环和两段直梁构成。分析了有限元的单元尺度对固有频率及频率差的影响以及压电陶瓷片的粘贴位置对固有频率及弯曲振型的影响。对自行研制的超声电机进行了实验研究。实验结果表明，固有频率差的数值计算值与相应的共振频率之差吻合。     

The E3 architecture: enabling future cellular networks with cognitive and self‐x capabilities

Future mobile networks are expected to be complex heterogeneous systems. On the one hand this will enable users to take advantage of a number of different access technologies. On the other hand it will seriously affect network management procedures since more extensive operations and decisions will have to be dealt with. To tackle these challenges a number of new dynamic mechanisms need to be designed. It is imperative that certain network management tasks have to be performed without human intervention to reduce the OPEX costs and achieve faster responses in different events. To achieve this goal, the introduction of self‐x functionalities, combined with cognitive mechanisms and the ability to reconfigure network entities and terminals, is required. Moreover, the introduction of a new pilot channel needs to be considered to assist the terminals in selecting the most suitable radio access technology according to their requirements. We present the functional architecture of an evolved network that was designed in the context of the EU‐funded IP project ‘E³: End‐to‐End Efficiency’. This architecture aims to enhance existing procedures usually performed in traditional operation and maintenance systems (e.g. spectrum management, network planning, configuration actions). We explain the rationale of our design and provide specific examples to illustrate the role of the different functional entities and their interfaces. A considerable part of this architecture has recently been approved as a feasibility study by the ETSI Committee Reconfigurable Radio System. Copyright © 2010 John Wiley & Sons, Ltd.     

Hydrogen‐Bonded Organic Semiconductors as Stable Photoelectrocatalysts for Efficient Hydrogen Peroxide Photosynthesis

Research on semiconductor photocatalysts for the conversion of solar energy into chemical fuels has been at the forefront of renewable energy technologies. Water splitting to produce H₂ and CO₂ reduction to hydrocarbons are the two prominent approaches. A lesser‐known process, the conversion of solar energy into the versatile high‐energy product H₂O₂ via reduction of O₂ has been proposed as an alternative concept. Semiconductor photoelectrodes for the direct photosynthesis of H₂O₂ from O₂ have not been applied up to now. Photoelectrocatalytic oxygen reduction to peroxides in aqueous electrolytes by hydrogen‐bonded organic semiconductor is observed photoelectrodes. These materials have been found to be remarkably stable operating in a photoelectrochemical cell converting light into H₂O₂ under constant illumination for at least several days, functioning in a pH range from 1 to 12. This is the first report of a semiconductor photoelectrode for H₂O₂ production, with catalytic performance exceeding prior reports on photocatalysts by one to two orders of magnitude in terms of peroxide yield/catalyst amount/time. The combination of a strongly reducing conduction band energy level with stability in aqueous electrolytes opens new avenues for this widely available materials class in the field of photo(electro) catalysis.     

Free radical fast photo-cured gate dielectric for top-gate polymer field effect transistors

We demonstrated top-gate organic field effect transistors (OFETs) made with free radical photo-cured polymer gate dielectrics and poly(3-hexylthiophene). We introduced a new approach of cross linking dielectric polymers in OFETs by using acrylate monomers cured with UV irradiation directly on the semiconductor. Three different blends were formulated: one self-initiating acrylate oligomer and two epoxy acrylate monomers mixed with 4-phenylbenzophenone as photo initiator and N-methyldiethanolamine as amine synergist. Thin films of these blends were cured in air within one minute. The curing process was monitored with FT-IR spectroscopy and the effect of a wetting agent was studied by measuring the CV characteristics of metal–insulator-semiconductor (MIS) structures made with these formulations. OFETs made with the demonstrated formulations showed high on/off ratios (10⁵–10⁶) and low sub-threshold slopes (0.44–1.42 V/dec).