Qualitative Properties of alpha-Weighted Scheduling Policies

We consider a switched network, a fairly general constrained queueing network model that has been used successfully to model the detailed packet-level dynamics in communication networks, such as input-queued switches and wireless networks. The main operational issue in this model is that of deciding which queues to serve, subject to certain constraints. In this paper, we study qualitative performance properties of the well known $\alpha$-weighted scheduling policies. The stability, in the sense of positive recurrence, of these policies has been well understood. We establish exponential upper bounds on the tail of the steady-state distribution of the backlog. Along the way, we prove finiteness of the expected steady-state backlog when $\alpha<1$, a property that was known only for $\alpha\geq 1$. Finally, we analyze the excursions of the maximum backlog over a finite time horizon for $\alpha \geq 1$. As a consequence, for $\alpha \geq 1$, we establish the full state space collapse property.Comment: 13 page

Research communication for immediate impact: climate adaptation in Australia

Abstract Research into climate change adaptation is challenged by funding organisations to demonstrate immediate research impact through near term reference in sector- specific communication and policy documents. Critically, research funded to inform decision makers and current policy about adapting to climate change must engage with end users and implement communication initiatives that lead to research adoption. Moreover, researchers need to better understand the components that contribute to effective engagement and communication to plan successful strategies to engage with the range of vulnerable sectors affected by climate change. Given the importance of research application, Primary Investigators for National Climate Change Adaptation Research Facility (NCCARF) funded projects had to consider end user engagement and communication. This paper identifies some common factors in three NCCARF cases which successfully demonstrated swift access to climate adaptation research in three sectors; human health, emergency management, and settlements and infrastructure. Early and ongoing engagement between researchers and the intended knowledge users shaped both the research focus and output formats. Stakeholders involved in coordinated and sustained communication programs disseminated and promoted the research through multiple channels. These agents of dissemination included; funders (NCCARF, universities and industry bodies); information users (government agencies and professional bodies), and both mass media and social media

Indium substitution effect on the topological crystalline insulator family (Pb1−x_{1-x}Snx_{x})1−y_{1-y}Iny_{y}Te: Topological and superconducting properties

Topological crystalline insulators (TCIs) have been of great interest in the area of condensed matter physics. We investigated the effect of indium substitution on the crystal structure and transport properties in the TCI system (Pb$_{1-x}$Sn$_{x}$)$_{1-y}$In$_{y}$Te. For samples with a tin concentration $x\le50\%$, the low-temperature resisitivities show a dramatic variation as a function of indium concentration: with up to ~2% indium doping the samples show weak-metallic behavior, similar to their parent compounds; with ~6% indium doping, samples have true bulk-insulating resistivity and present evidence for nontrivial topological surface states; with higher indium doping levels, superconductivity was observed, with a transition temperature, Tc, positively correlated to the indium concentration and reaching as high as 4.7 K. We address this issue from the view of bulk electronic structure modified by the indium-induced impurity level that pins the Fermi level. The current work summarizes the indium substitution effect on (Pb,Sn)Te, and discusses the topological and superconducting aspects, which can be provide guidance for future studies on this and related systems.Comment: 16 pages, 8 figure

Higgs Inflation, Reheating and Gravitino Production in No-Scale Supersymmetric GUTs

We extend our previous study of supersymmetric Higgs inflation in the context of no-scale supergravity and grand unification, to include models based on the flipped SU(5) and the Pati-Salam group. Like the previous SU(5) GUT model, these yield a class of inflation models whose inflation predictions interpolate between those of the quadratic chaotic inflation and Starobinsky-like inflation, while avoiding tension with proton decay limits. We further analyse the reheating process in these models, and derive the number of e-folds, which is independent of the reheating temperature. We derive the corresponding predictions for the scalar tilt and the tensor-to-scalar ratio in cosmic microwave background perturbations, as well as discussing the gravitino production following inflation.Comment: JCAP Final Version. 23pp, 3 Figs. Only minor refinements, references adde

Deep Long Short-Term Memory Adaptive Beamforming Networks For Multichannel Robust Speech Recognition

Far-field speech recognition in noisy and reverberant conditions remains a challenging problem despite recent deep learning breakthroughs. This problem is commonly addressed by acquiring a speech signal from multiple microphones and performing beamforming over them. In this paper, we propose to use a recurrent neural network with long short-term memory (LSTM) architecture to adaptively estimate real-time beamforming filter coefficients to cope with non-stationary environmental noise and dynamic nature of source and microphones positions which results in a set of timevarying room impulse responses. The LSTM adaptive beamformer is jointly trained with a deep LSTM acoustic model to predict senone labels. Further, we use hidden units in the deep LSTM acoustic model to assist in predicting the beamforming filter coefficients. The proposed system achieves 7.97% absolute gain over baseline systems with no beamforming on CHiME-3 real evaluation set.Comment: in 2017 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP

Experiments with double microwave apertures

One of the significant characterizations of microwave imaging is the spatial resolution. The relative long wavelength of microwaves as compared to ultrasonic waves and x-rays necessarily means that aperture arrays (real-time or synthetic) are required for high-resolution microwave imaging. Certain limitations on resolution apply regardless of how the array is realized. Types of antenna arrays fall into two broad categories: Phased arrays which are usually operated in real time by scanning a beam past an object, and aperture synthesis in which data are collected with one or more antennas and later processed to produce an image. In NDE we are concerned with the linear resolution which we define as the product of the angular resolution and the range from the array phase center to the object of interest. For objects imaged in the far field of the array, the angular resolution is inversely proportional to the largest size of the array. We have conducted a series of experiments to study the practical and mathematical aspects of resolution when the object of interest is physically near the microwave apertures