Parameter Selection and Pre-Conditioning for a Graph Form Solver

In a recent paper, Parikh and Boyd describe a method for solving a convex optimization problem, where each iteration involves evaluating a proximal operator and projection onto a subspace. In this paper we address the critical practical issues of how to select the proximal parameter in each iteration, and how to scale the original problem variables, so as the achieve reliable practical performance. The resulting method has been implemented as an open-source software package called POGS (Proximal Graph Solver), that targets multi-core and GPU-based systems, and has been tested on a wide variety of practical problems. Numerical results show that POGS can solve very large problems (with, say, more than a billion coefficients in the data), to modest accuracy in a few tens of seconds. As just one example, a radiation treatment planning problem with around 100 million coefficients in the data can be solved in a few seconds, as compared to around one hour with an interior-point method.Comment: 28 pages, 1 figure, 1 open source implementatio

Distinguished Preduals of Spaces of Holomorphic Functions

Sin resume

Non-Orthogonal Contention-Based Access for URLLC Devices with Frequency Diversity

We study coded multichannel random access schemes for ultra-reliable low-latency uplink transmissions. We concentrate on non-orthogonal access in the frequency domain, where users transmit over multiple orthogonal subchannels and inter-user collisions limit the available diversity. Two different models for contention-based random access over Rayleigh fading resources are investigated. First, a collision model is considered, in which the packet is replicated onto $K$ available resources, $K' \leq K$ of which are received without collision, and treated as diversity branches by a maximum-ratio combining (MRC) receiver. The resulting diversity degree $K'$ depends on the arrival process and coding strategy. In the second model, the slots subject to collisions are also used for MRC, such that the number of diversity branches $K$ is constant, but the resulting combined signal is affected by multiple access interference. In both models, the performance of random and deterministic repetition coding is compared. The results show that the deterministic coding approach can lead to a significantly superior performance when the arrival rate of the intermittent URLLC transmissions is low.Comment: 2019 IEEE 20th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC) - Special Session on Signal Processing for NOMA Communication System

Assessment, Optimization, And Enhancement Of Ultrafiltration (uf) Membrane Processes In Potable Water Treatment

This dissertation reports on research related to ultrafiltration (UF) membranes in drinking water applications. A pilot-scale investigation identified seasonal surface water quality impacts on UF performance and resulted in the development of a dynamic chemically enhanced backwash protocol for fouling management. Subsequent analysis of UF process data revealed limitations with the use of specific flux, transmembrane pressure (TMP), and other normalization techniques for assessing UF process fouling. A new TMP balance approach is presented that identifies the pressure contribution of membrane fouling and structural changes, enables direct process performance comparisons at different operating fluxes, and distinguishes between physically and chemically unresolved fouling. In addition to the TMP balance, a five component optimization approach is presented for the systematic improvement of UF processes on the basis of TMP variations. Terms are defined for assessing process event performance, a new process utilization term is presented to benchmark UF productivity, and new measures for evaluating maintenance procedures are discussed. Using these tools, a correlation between process utilization and operating pressures was established and a sustainable process utilization of 93.5% was achieved. UF process capabilities may be further enhanced by pre-coating media onto the membrane surface. Silicon dioxide (SiO2) and powdered activated carbon (PAC) are evaluated as precoating materials, and the applicability of the TMP balance for assessing pre-coated membrane performance is demonstrated. The first use of SiO2 as a support layer for PAC in a membrane pre-coating application is presented at the laboratory-scale. SiO2-PAC pre-coatings successfully reduced physically unresolved fouling and enhanced UF membrane organics removal capabilities

Characterisation of NanoDot optically stimulated luminescent dosimeters for in vivo radiotherapy dosimetry

Al2O3:C has increasingly been used for optically stimulated luminescence (OSL) dosimetry, initially for personal dosimeters and more recently through the Landauer commercial OSL system for dosimetry. The system couples the InLight® microStar reader with NanoDot® dosimeters that were then paired with a GammaSonics® manual annealing lightbox to perform robust, simple and reliable dosimetry

Examining (international) law: towards a systematic, coherent and radical theory

This thesis examines accounts of law – and more particularly public international law – provided by Marxian scholarship. It does so with the aim of revealing and analysing those aspects which can help build the conceptual framework necessary for the creation of a systematic, coherent and radical theory of the contemporary world order. In order to be intellectually satisfying and practically useful, such a theory must be capable of addressing the relationships amongst law, state and economy at the global level, and accounting for the form, content, function and structure of the global legal order. Throughout, this thesis draws on a number of different traditions of legal, political and economic thought from American Legal Realism and French Structuralism to World Polity Theory and Pashukanite and Gramscian Marxism. However, it seeks to highlight, in particular, those insights available from theorists whose works have hitherto failed to receive the attention they deserve within critical international legal scholarship because of their primary association with domestic legal or political criticism. The intention in doing so is to demonstrate the benefits of rejecting the a priori distinction between the domestic and international legal fields so common within orthodox legal scholarship on both sides of the divide. What is hoped will be provided by such a rejection is the conceptual space for generating a theory relevant not simply to public international law but to every legal field and, thus, ‘the Law’ as a whole

Holomorphic Basis for Families of Subspaces of a Banach Space

In this article we investigate the connection between a family of com-plemented subspaces of a Banach space having a holomorphic basis, and being holomorphically complemented