On the selection of connectivity-based metrics for WSNs using a classification of application behaviour

This paper addresses a subset of Wireless Sensor Network (WSN) applications in which data is produced by a set of resource-constrained source nodes and forwarded to one or more sink nodes. The performance of such applications is affected by the connectivity of the WSN, since nodes must remain connected in order to transfer data from sources to sinks. Designers use metrics to measure and improve the efficacy of WSN applications. We aim to facilitate the choice of connectivity-based metrics by introducing a classification of WSN applications based on their data collection behaviour and indicating the metrics best suited to the evaluation of particular application classes. We argue that no suitable metric currently exists for a significant class of applications with the following characteristics: 1) application data is periodically routed or disseminated from source nodes to one or more sink nodes, and 2) the application can continue to function with the loss of source nodes although its useful network lifetime diminishes as a result. We present a new metric, known as Connectivity Weighted Transfer, which may be used to evaluate WSN applications with these characteristics.Preprin

The Definition and Choice of Environmental Commodities for Nonmarket Valuation

Economic analyses of nature must somehow define the “environmental commodities” to which values are attached. This paper articulates a set of principles to guide the choice and interpretation of nonmarket commodities. We describe how complex natural systems can be decomposed consistent with what can be called “ecological production theory.” Ecological production theory--like conventional production theory--distinguishes between biophysical inputs, process, and outputs. We argue that a systems approach to the decomposition and presentation of natural commodities can inform and possibly improve the validity of nonmarket environmental valuation studies. We raise concerns about the interpretation, usefulness, and accuracy of benefit estimates derived without reference to ecological production theory.nonmarket valuation, stated preference, revealed preference, commodities, endpoints

Intel's XL Permit: A Framework for Evaluation

The paper develops a framework to evaluate permits granted to firms under the Environmental Protection Agency's Project XL � with emphasis on the novel air permit granted to the Intel Corporation. We describe the permit, the process that created it, and the types of costs and benefits likely to arise from this type of "facility-specific" regulatory arrangement. Among other things, the paper describes the permit's impact on environmental quality, production costs, transaction costs, and Intel's strategic market position. The paper also considers how an estimate of the costs and benefits � both to Intel and society � might be estimated. While facility-specific regulation typically conjures images of production cost savings as processes are re-engineered and low-cost abatement strategies pursued, the Intel case highlights perhaps a more important source of benefit: flexibility in the form of streamlined permitting. Flexibility in this form allows for accelerated product introductions, with potentially significant benefits to the firm and possibly to society.

Recording and Analysis of Head Movements, Interaural Level and Time Differences in Rooms and Real-World Listening Scenarios

The science of how we use interaural differences to localise sounds has been studied for over a century and in many ways is well understood. But in many of these psychophysical experiments listeners are required to keep their head still, as head movements cause changes in interaural level and time differences (ILD and ITD respectively). But a fixed head is unrealistic. Here we report an analysis of the actual ILDs and ITDs that occur as people naturally move and relate them to gyroscope measurements of the actual motion. We used recordings of binaural signals in a number of rooms and listening scenarios (home, office, busy street etc). The listener's head movements were also recorded in synchrony with the audio, using a micro-electromechanical gyroscope. We calculated the instantaneous ILD and ITDs and analysed them over time and frequency, comparing them with measurements of head movements. The results showed that instantaneous ITDs were widely distributed across time and frequency in some multi-source environments while ILDs were less widely distributed. The type of listening environment affected head motion. These findings suggest a complex interaction between interaural cues, egocentric head movement and the identification of sound sources in real-world listening situations

NEGLIGENCE-GAS-DUTY TO INSPECT ABANDONED PIPES

Three persons were asphyxiated in a house in which they were sleeping when pressure caused by the settling of the house broke a gas pipe underneath. The house had no foundation but was supported by posts. Gas service had been discontinued eighteen years before, and the meter was removed at that time. The gas, however, had not been shut off at the curb but was allowed by the company to remain in the pipes beneath the house. The defendant gas company had made no inspection since the service had been discontinued. The plaintiffs, representatives of the deceased persons, brought actions, consolidated for trial, alleging that the defendant gas company was negligent in failing to inspect, maintain, remove and shut off the gas pipes. On appeal from a judgment dismissing the complaints, held, affirmed, three judges dissenting. Failure to shut off the gas at the street curb is not negligent per se, and a gas company is not under a duty to inspect premises beneath which pipes are laid unless it knows that there is possible danger. Shaw v. Wisconsin Power & Light Co., 256 Wis. 176, 40 N.W. (2d) 498 (1949)

Problems of Practice in Large Cities

A Symposium on Post War Problems of the Legal Profession

Problems of Practice in Large Cities

A Symposium on Post War Problems of the Legal Profession