Learning-aided Stochastic Network Optimization with Imperfect State Prediction

We investigate the problem of stochastic network optimization in the presence of imperfect state prediction and non-stationarity. Based on a novel distribution-accuracy curve prediction model, we develop the predictive learning-aided control (PLC) algorithm, which jointly utilizes historic and predicted network state information for decision making. PLC is an online algorithm that requires zero a-prior system statistical information, and consists of three key components, namely sequential distribution estimation and change detection, dual learning, and online queue-based control. Specifically, we show that PLC simultaneously achieves good long-term performance, short-term queue size reduction, accurate change detection, and fast algorithm convergence. In particular, for stationary networks, PLC achieves a near-optimal $[O(\epsilon)$, $O(\log(1/\epsilon)^2)]$ utility-delay tradeoff. For non-stationary networks, \plc{} obtains an $[O(\epsilon), O(\log^2(1/\epsilon)$ $+ \min(\epsilon^{c/2-1}, e_w/\epsilon))]$ utility-backlog tradeoff for distributions that last $\Theta(\frac{\max(\epsilon^{-c}, e_w^{-2})}{\epsilon^{1+a}})$ time, where $e_w$ is the prediction accuracy and $a=\Theta(1)>0$ is a constant (the Backpressue algorithm \cite{neelynowbook} requires an $O(\epsilon^{-2})$ length for the same utility performance with a larger backlog). Moreover, PLC detects distribution change $O(w)$ slots faster with high probability ($w$ is the prediction size) and achieves an $O(\min(\epsilon^{-1+c/2}, e_w/\epsilon)+\log^2(1/\epsilon))$ convergence time. Our results demonstrate that state prediction (even imperfect) can help (i) achieve faster detection and convergence, and (ii) obtain better utility-delay tradeoffs

An Automated System to Mitigate Loss of Life at Unmanned Level Crossings

AbstractEvery life is precious and is worth saving. This paper proposes the design and implementation of a system to mitigate the loss of life at unmanned railway level crossings. This system uses the advancements in Communication, Embedded Systems and Internet of Things to develop a real-time, early warning system for unmanned level crossings across India. The outcome of this work is to provide an audio-visual indication to the commuter warning about an approaching train. The need for such systems and its design implementation and feasibility is discussed in this paper

Measurement and modeling of multiuser multiantenna system in aircraft in the presence of electromagnetic noise and interference

ManuscriptThis paper evaluates the accuracy with which the performance of a multi-user multi-antenna system can be predicted with and without considering co-channel interference and noise (Gaussian, α- stable and Cauchy) using a site-specific 3D ray-tracing algorithm as well as with statistical models with Gaussian and Nakagami-m channel models in small to medium sized aircraft. These models expand on previous statistical channel models such as the hyper-Rayleigh model by including the simultaneous effects of co- and adjacent channel interference, antenna matching, efficiency, directivity and polarization as well as (for the 3D model) site-specific multipath effects. Measurements and comparisons are made in a metallic-bodied Beech Baron BE 58P and a composite structure Rockwell T-39 Sabreliner. It was found that the 3D ray tracing model provides a mean capacity within 1 % of those measured in the two aircraft in the presence of interference and noise. This was closely followed by the Nakagami-m distribution (m=1.4) which was within 1-3% of measured capacity in the presence of interference and within 6% for a combination of interference and noise and the Gaussian model which was within 6% of measured capacity in the presence of interference and within 11% for a combination of interference and noise . The Cauchy noise degraded the capacity more than the other types of noise in the aircraft, providing a lower bound for capacity in an aircraft system

Antenna optimization for vehicular environments

Journal ArticleAbstract? This paper presents a multi-antenna optimization for communication in a Rockwell T-39 Sabreliner, a mid-size aircraft with a metallic body. The aircraft channel at 2.45 GHz is modeled using site specific 3D ray-tracing software. Added effects from system details including the antenna radiation patterns, mutual coupling, etc. are incorporated into a network theory based detailed signal model. The paper considers traditional antennas including dipoles, square patches, PIFAs, and polarization agile patches along with some more complex shaped patches and PIFAs. A random search algorithm was used to optimize capacity for arrays with widely divergent element count, element type, matching, directivity, polarization alignment, efficiency, spatial correlation and coupling. The polarization agile patch provides the best capacity for locations near the aircraft ceiling while the PIFAs with more variety in shape (spiral shapes) provide the best capacity for locations near the floor. This is because the signals reaching the roof and sides contain more polarization diversity than those in the center of the body where the nonconductive floor is located

X-ray photoelectron spectroscopic investigation of phenosafranine adsorbed onto micro and mesoporous materials

The phenosafranine adsorbed onto the micro and mesoporous materials prepared by ion exchange method and interaction of the dye with host materials were studied by X-ray photoelectron spectroscopy to elucidate the influence of the host matrix on the binding energy of N 1s orbital. Core level N 1s X-ray photoelectron spectroscopy reveals the interaction between the dye and the solid surface through the hydrogen bonding between the hydrogen atoms of primary amino groups in dye molecule and the oxygen atom of surface hydroxyl groups. The strength of the hydrogen bonding depends on the nature of the solid surface. In the dye adsorbed onto the micro and mesoporous materials the interaction between adsorbed phenosafranine and the surfaces of the porous materials are found to modify the optical spectra and the excited state dynamics of the confined phenosafranine molecules. The change in photophysical properties of phenosafranine adsorbed on to the host materials on dehydration at elevated temperatures is attributed to the modification of host surface during dehydration process

Low latency via redundancy

Low latency is critical for interactive networked applications. But while we know how to scale systems to increase capacity, reducing latency --- especially the tail of the latency distribution --- can be much more difficult. In this paper, we argue that the use of redundancy is an effective way to convert extra capacity into reduced latency. By initiating redundant operations across diverse resources and using the first result which completes, redundancy improves a system's latency even under exceptional conditions. We study the tradeoff with added system utilization, characterizing the situations in which replicating all tasks reduces mean latency. We then demonstrate empirically that replicating all operations can result in significant mean and tail latency reduction in real-world systems including DNS queries, database servers, and packet forwarding within networks

A novel conductometric titration approach for rapid determination of boron

21-30In laboratories dealing with radioactive samples it is important to minimize both the sample size and also the associated waste generated in an analysis. To meet this objective a rapid conductometric titration technique is developed to determine boron in the moderators of Pressurized Heavy Water Reactors (PHWR’s). Using this novel PC interfaced titration facility a minimum tenfold reduction in sample size is achieved compared to conventional conductometric titration. Determination of boron is based on the conversion of extremely weak boric acid to better conducting boron mannitol complex and titrating the complex against NaOH. Various parameters affecting the analysis, when moving from large to small sample size, are analyzed and optimized. The technique is primarily proposed for the assay of boron (≥0.5 ppm) during reactor startup. Each analysis requires less than 10 min. The detection limit is 0.5 ppm and the precision obtained at this level is 4.6% RSD. The technique is a good alternative to less sensitive carminic acid based spectrophotometric method

Tachyon: Reliable, Memory Speed Storage for Cluster Computing Frameworks

Tachyon is a distributed file system enabling reliable data sharing at memory speed across cluster computing frameworks. While caching today improves read workloads, writes are either network or disk bound, as replication is used for fault-tolerance. Tachyon eliminates this bottleneck by pushing lineage, a well-known technique, into the storage layer. The key challenge in making a long-running lineage-based storage system is timely data recovery in case of failures. Tachyon addresses this issue by introducing a checkpointing algorithm that guarantees bounded recovery cost and resource allocation strategies for recomputation under commonly used resource schedulers. Our evaluation shows that Tachyon outperforms in-memory HDFS by 110x for writes. It also improves the end-to-end latency of a realistic workflow by 4x. Tachyon is open source and is deployed at multiple companies.National Science Foundation (U.S.) (CISE Expeditions Award CCF-1139158)Lawrence Berkeley National Laboratory (Award 7076018)United States. Defense Advanced Research Projects Agency (XData Award FA8750-12-2-0331