2,739 research outputs found
Comparison of material properties of SCC concrete with steel fibres related to ingress of chlorides
The paper focuses on the evaluation of chloride ion diffusion coefficient of self-compacting concrete with steel fibre reinforcement. The reference concrete from Ordinary Portland Cement (OPC) and Self-Compacting Concrete (SCC) with several values of added steel fibres-0%, 1% and 2% of weight-were cast in order to investigate the effect of fibres. The three procedures of diffusion coefficient calculation are presented-rapid chloride penetration test, accelerated penetration tests with chloride as well as the surface measurement of electrical resistivity using Wenner probe. The resulting diffusion coefficients obtained by all methods are compared and evaluated regarding the basic mechanical properties of concrete mixtures.Web of Science103art. no. 22
RATE COMPATIBLE PUNCTURED TURBO-CODED HYBRID ARQ FOR OFDM SYSTEM
Now a day’s orthogonal frequency division multiplexing (OFDM) is under intense research for broadband wireless transmission because of its robustness against multipath fading. A major concern in data communication such as OFDM is to control transmission errors caused by the channel noise so that error free data can be delivered to the user. Rate compatible punctured turbo (RCPT) coded hybrid ARQ (RCPT HARQ) has been found to give improved throughput performance in a OFDM system. However the extent to which the RCPT HARQ improves the throughput performance of the OFDM system has not been fully understood. HARQ has been suggested as a means of providing high data rate and high throughput communication in next generation systems through diversity combining transmit attempts at the receiver. The combination of RCPT HARQ with OFDM provides significant bandwidth at close to capacity rates of channel. In this paper, we evaluate by computer simulations the throughput performance of RCPT code HARQ for OFDM system as compared to that of conventional OFDM
AC Josephson effect and resonant Cooper pair tunneling emission of a Cooper Pair Transistor
We measure the high-frequency emission of a single Cooper pair
transistor(SCPT) in the regime where transport is only due to tunneling of
Cooper pairs. This is achieved by coupling on-chip the SCPT to a
superconductor-insulator-superconductor junction and by measuring the photon
assisted tunneling current of quasiparticles across the junction. This
technique allows a direct detection of the AC Josephson effect of the SCPT and
provides evidence of Landau-Zener transitions for proper gate voltage. The
emission in the regime of resonant Cooper pair tunneling is also investigated.
It is interpreted in terms of transitions between charge states coupled by the
Josephson effect.Comment: Revtex4, 5 pages, 4 figures, final versio
Robust And Optimal Opportunistic Scheduling For Downlink 2-Flow Network Coding With Varying Channel Quality and Rate Adaptation
This paper considers the downlink traffic from a base station to two
different clients. When assuming infinite backlog, it is known that
inter-session network coding (INC) can significantly increase the throughput of
each flow. However, the corresponding scheduling solution (when assuming
dynamic arrivals instead and requiring bounded delay) is still nascent.
For the 2-flow downlink scenario, we propose the first opportunistic INC +
scheduling solution that is provably optimal for time-varying channels, i.e.,
the corresponding stability region matches the optimal Shannon capacity.
Specifically, we first introduce a new binary INC operation, which is
distinctly different from the traditional wisdom of XORing two overheard
packets. We then develop a queue-length-based scheduling scheme, which, with
the help of the new INC operation, can robustly and optimally adapt to
time-varying channel quality. We then show that the proposed algorithm can be
easily extended for rate adaptation and it again robustly achieves the optimal
throughput. A byproduct of our results is a scheduling scheme for stochastic
processing networks (SPNs) with random departure, which relaxes the assumption
of deterministic departure in the existing results. The new SPN scheduler could
thus further broaden the applications of SPN scheduling to other real-world
scenarios
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