Lachlan L. H. Andrew
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View article: Optimal bounds on a tree inference algorithm
Optimal bounds on a tree inference algorithm Open
This paper tightens the best known analysis of Hein's 1989 algorithm to infer the topology of a weighted tree based on the lengths of paths between its leaves. It shows that the number of length queries required for a degree-$k$ tree of $n…
View article: A Benchmark for Math Misconceptions: Bridging Gaps in Middle School Algebra with AI-Supported Instruction
A Benchmark for Math Misconceptions: Bridging Gaps in Middle School Algebra with AI-Supported Instruction Open
This study introduces an evaluation benchmark for middle school algebra to be used in artificial intelligence(AI) based educational platforms. The goal is to support the design of AI systems that can enhance learner conceptual understandin…
View article: Three-phase voltage sensitivity estimation and its application to topology identification in low-voltage distribution networks
Three-phase voltage sensitivity estimation and its application to topology identification in low-voltage distribution networks Open
This paper aims to estimate the three-phase voltage sensitivity matrix and the network topology of a low-voltage distribution network from smart meter data, which measures voltage magnitude, current magnitude, and power factor with a lead/…
View article: Debugging the Linux Madwifi driver
Debugging the Linux Madwifi driver Open
This report describes a bug in the fragmentation code of the Madwifi driver for the Atheros chipset under the Linux kernel. The bug is due to incorrect locking of a data structure. Techniques for Linux kernel debugging are described, and a…
View article: Does header length affect performance in optical burst switched networks?
Does header length affect performance in optical burst switched networks? Open
We investigate the effect of nonnegligible header length (HL) in optical burst switching on blocking probability. The HL is the total delay of a control packet at the controller. We first develop a model that explicitly presents the distri…
View article: MaxNet: an efficient Max-Mi fair allocation scheme
MaxNet: an efficient Max-Mi fair allocation scheme Open
It has been analytically proved that both MaxNet and SumNet can achieve max-min fair allocation in static networks. In SumNet networks, such as the TCP algorithm of the current Internet, the source rate is controlled by congestion signal w…
View article: Robust control of an M/G/1 processor sharing queue with applications to energy management
Robust control of an M/G/1 processor sharing queue with applications to energy management Open
The Internet contains many devices that must process multiple jobs at the same time. For many purposes, such devices can be modelled as M/G/1-PS queues. This report investigates such a queue. We consider single-pass, lossless, queueing sys…
View article: User-optimal storage with rising energy prices
User-optimal storage with rising energy prices Open
When energy prices fluctuate, small scale storage, such as provided by electric vehicles or uninterruptible power supplies, allows users to reduce their overall costs by buying in price troughs. However, if future prices are rising, a user…
View article: Experimental evaluation of delay/loss-based TCP congestion control algorithms
Experimental evaluation of delay/loss-based TCP congestion control algorithms Open
We present initial experimental results for TCP Illinois and Compound TCP. These tests are for relatively simple scenarios yet they are sufficient to highlight several interesting issues. We observe that both TCP Illinois and Compound TCP …
View article: New adaptive image sequence coding scheme using Kohonen's SOFM
New adaptive image sequence coding scheme using Kohonen's SOFM Open
This paper presents a novel adaptive vector quantization scheme based on the SOFM neural network. All adaptation is performed directly from the quantized image with no explicit adaptation information transmitted or stored. Thus the network…
View article: Two bits are enough
Two bits are enough Open
We design a congestion control protocol that uses the existing IP ECN bits to achieve efficient and fair bandwidth allocations on high Bandwidth-Delay Product (BDP) paths while maintaining low persistent queue length and negligible packet …
View article: Algorithms for dynamic capacity provisioning
Algorithms for dynamic capacity provisioning Open
Data centre power consumption can be reduced by switching off servers during low load. However, excess switching is wasteful. This paper reviews online algorithms for optimizing this tradeoff, including the benefits of shifting load betwee…
View article: CLAMP: Maximizing the performance of TCP over low bandwidth variable rate access links
CLAMP: Maximizing the performance of TCP over low bandwidth variable rate access links Open
This paper presents CLAMP, a distributed algorithm to enhance the performance of TCP connections that terminate in a wireless access network. CLMAP works at a receiver to control a TCP sender by setting the TCP receiver's advertised window…
View article: Filtered Gibbs sampler for estimating blocking probabilities in WDM optical networks
Filtered Gibbs sampler for estimating blocking probabilities in WDM optical networks Open
Blocking probabilities in Wavelength Division Multiplex optical networks are hard to compute for realistic sized systems, even though analytical formulas for the distribution exist (under maximal packing of wavelengths) . This computationa…
View article: A tale of two metrics: simultaneous bounds on competitiveness and regret
A tale of two metrics: simultaneous bounds on competitiveness and regret Open
We consider algorithms for 'smoothed online convex optimization' (SOCO) problems, which are a hybrid between online convex optimization (OCO) and metrical task system (MTS) problems. Historically, the performance metric for OCO was regret …
View article: Neural networks for image coding: a review
Neural networks for image coding: a review Open
Images are forming an increasingly large part of modern communications, bringing the need for efficient and effective compression. This survey aims to give the reader a feel for the wide range of ways in which neural network technology has…
View article: Fairness comparison of FAST TCP and TCP Vegas
Fairness comparison of FAST TCP and TCP Vegas Open
This paper compares the equilibrium properties of FAST TCP and TCP Vegas. Although the two have the same equilibrium point when all sources know their true propagation delays, FAST is fairer when there are estimation errors. The performanc…
View article: Towards a common TCP evaluation suite
Towards a common TCP evaluation suite Open
This document presents an evaluation test suite for the initial evaluation of proposed TCP modifications. The goal of the test suite is to allow researchers quickly and easily to evaluate their proposed TCP extensions in simulators and tes…
View article: Improving the robustness of fuzzy logic ATM ABR rate control for large round trip times
Improving the robustness of fuzzy logic ATM ABR rate control for large round trip times Open
For ABR to be a practical part of ATM, its rate must be able to be controlled effectively even in the presence of a large round trip time (RTT). A simple fuzzy logic controller was recently shown to perform poorly in networks with large RT…
View article: Incremental deployment of new ECN-compatible congestion control
Incremental deployment of new ECN-compatible congestion control Open
Congestion control can be improved by using more accurate congestion feedback from the network. However, when new protocols either do not obtain information from all congested network elements, or share resources with existing congestion c…
View article: Dual queue approach to improving network performance during transient congestion episodes
Dual queue approach to improving network performance during transient congestion episodes Open
Despite extensive work on the network congestion[Jain, 1990], network congestion remains a real problem. The solution is not one answer, but many. Call admission controls try to limit the number of sessions according to the network's traff…
View article: Filtered Gibbs sampler for estimating blocking in product form networks
Filtered Gibbs sampler for estimating blocking in product form networks Open
The filtered Gibbs sampler (FGS) is a very simple yet efficient method of performance evaluation for a class of communication networks. This paper confirms that the FGS is considerably more efficient than the standard Gibbs sampler. It als…
View article: Wavelength-continuous WDM networks with non-uniform service rates
Wavelength-continuous WDM networks with non-uniform service rates Open
Many circuit switched networks have stationary state probabilities which depend on the arrival and service rates only through their ratio. This paper shows that this is not the case for WDM networks without wavelength conversion, and for c…
View article: WAN-in-Lab: motivation, deployment and experiments
WAN-in-Lab: motivation, deployment and experiments Open
WAN-in-Lab is a hardware testbed for the design, development, testing and evaluation of high speed network protocols. It uses real carrier-class networking hardware to avoid the artifacts introduced by network simulation and emulation, whi…
View article: Optimization of Shared Autonomous Electric Vehicles Operations
Optimization of Shared Autonomous Electric Vehicles Operations Open
View article: A Method to Control Distributed Energy Resources in Distribution Networks Using Smart Meter Data
A Method to Control Distributed Energy Resources in Distribution Networks Using Smart Meter Data Open
View article: Identifying Flexible Pool Pumps Suitable for Distributed Demand Response Schemes
Identifying Flexible Pool Pumps Suitable for Distributed Demand Response Schemes Open
Demand response will be an important tool as non-dispatchable generation is added to the grid. Swimming pool filtration pumps are a promising appliance for the grid operator to control because, unlike air conditioners, their time of operat…
View article: Online Convex Optimization Using Predictions
Online Convex Optimization Using Predictions Open
Making use of predictions is a crucial, but under-explored, area of online algorithms. This paper studies a class of online optimization problems where we have external noisy predictions available. We propose a stochastic prediction error …