Estimating waste transfer station delays using GPS

This paper examines the use of on-board global positioning system (GPS) data recorders as a method to collect field data on the movements of solid waste collection vehicles at transfer stations. The movements of five waste collection vehicles using four different transfer facilities were compared over a period of 1 year. The spatial data were analyzed using geofences to determine the amount of time each truck spent on each of four activities: queuing for access to the weigh scale, sitting on the weigh scale, queuing for access to the tipping floor, and unloading waste. The study found that queuing delays can be identified and measured using GPS data. The average time at a facility for all trucks was 16.4min per visit, with a standard deviation of 14.3min. Time at the facility ranged between 2 and 111min per visit and the distribution of time at the facility was positively skewed. Multi-compartment vehicles (co-collection and recycling trucks) spent significantly more time at unloading facilities. There were also significant differences in the length and the location of the queues at different facilities. At one facility, the longest delays were encountered while waiting for the weigh scale, at two facilities trucks experienced delays in obtaining access to the tipping floor, while at the fourth facility no significant delays developed.     

Use of inert C&D materials for seawall foundation: quality control measures

The technical viability of using inert construction and demolition (C&D) materials for the construction of seawall and breakwater foundations has been established by laboratory testing of the materials, numerical analysis of foundation stability, and a pilot field-scale engineering performance evaluation. However, quality control measures are still required so that only suitable materials are used for seawall and breakwater foundation construction. The development of different quality control measures for different site conditions is presented in this paper. The rationale, practicality, and implementation of these quality control measures are also discussed.     

Compatible Blends of Zein and Polyvinylpyrrolidone

Blends of zein and polyvinylpyrrolidone (PVP) were compared based on their tensile properties, thermal properties and morphology. Zein was blended with polyvinylpyrrolidone of varying molecular weights (10, 55, and 1,300 kDa) and films were cast from ethanol solutions. Films cast using the higher molecular weight polymers showed an improvement in tensile strength, up to a 24% increase, compared to control. Differential scanning calorimetry data for the blends showed single T_m and T_g values of an intermediate value between those of zein and PVP control samples. Field emission scanning electron microscopy images show no obvious inhomogeneities, and confocal fluorescence microscopy showed no decreased uniformity in the PVP/zein films compared to control. Electrospun fibers of the zein/PVP blends were also obtained. These findings suggest that zein and polyvinylpyrrolidone combine to form a compatible blend, the first such blend of zein with a synthetic polymer.     

Simulated management effects on ammonia emissions from field applied manure

A need exists to improve the utilization of manure nutrients by minimizing NH₃ emissions from land application of manure. Management strategies to reduce NH₃ emissions are available; however, few have been validated under Canadian conditions. A well tested and accurate simulation model, however, can help overcome this challenge by determining appropriate management strategies for a given set of field conditions.     

Risk perception by offshore workers on UK oil and gas platforms

This paper reports the first investigation of risk perception by workers on offshore oil and gas installations on the UK Continental Shelf, following changes in offshore safety legislation in the wake of the Piper Alpha disaster in 1988. The Offshore Safety Case regulations (Health and Safety Executive, 1992, A Guide to the Offshore Installations (Safety Case) Regulations) put the onus on the operator to identify the major hazards and to reduce the risks to As Low As is Reasonably Practicable (ALARP). The regulations specifically state that Quantitative Risk Assessments (QRA) must be used when preparing the Safety Case. However, people do not use QRA when making everyday judgements about risk; they make subjective judgements known as risk perceptions, which are influenced by a number of different factors. This study was designed to complement the extensive QRA calculations that have already been carried out in the development of Safety Cases. The aim was to measure subjective risk perception in offshore personnel and examine how this relates to the more objective risk data available, namely accident records and QRA calculations. This paper describes the Offshore Risk Perception Questionnaire developed to collect the data and reports on UK offshore workers' perceptions of the risks associated with major and minor hazards, work tasks and other activities aboard production platforms.     

Simulation experiments comparing alternative process formulations using a factorial design

This paper reviews methods for exploring the differences between alternative equations in complex ecosystem models. A factorial design is proposed as a method for exposing possible interactions between equation forms in their effect on model output as well as to clarify differences between the main candidate equations. A number of display methods arising from statistical analysis are used including normal Q-Q plots, linear rank plots and interaction diagrams. The methods were illustrated using a complex ecosystem model of Lake Ontario. We found the methods effective at illustrating major differences between equations although several difficulties arose due to the complexity of the models and the diffuse nature of the data supporting model validation. Questions of the method for standardization of equation forms so that the compared equations are in some way analogous, are important. These methods are probably most useful in cases where the data are of sufficient quality to indicate not only how different equation forms affect model output but also which are to be preferred.     

Effects of water motion on propagule release from algae with complex life histories

Reproductive marine algae with complex life histories may respond differently to water motion depending upon whether the spore-producing or gamete-producing phase is considered. Two such species, the kelp Alaria esculenta (L.) Greville (Phaeophyceae) and Ulva lactuca L. (Chlorophyta), were examined experimentally in the laboratory. The kelp was collected in April–June 2000 and U. lactuca was collected in July–August 2000, from four intertidal habitats at Schoodic Point, Maine, USA. Orbital shakers were used to generate water motion. Sporophylls of A. esculenta released more zoospores under shaken versus calm conditions, whereas fewer antheridia on the microscopic male gametophytes released sperm under shaken versus calm conditions when male and female gametophytes were placed together. However, antheridial sperm release was equivalent when male gametophytes were exposed to undiluted media from dense cultures of mature female gametophytes under shaken versus calm conditions. These data suggest that water motion inhibited sperm release by diluting the sperm-releasing pheromone produced by ripe eggs below a threshold required to cause sperm release. Water motion stimulated both gamete and zoospore release from U. lactuca. This is the first report in an alga of stimulation of gamete release by increased water motion, but it is notable that parthenogenesis occurs in Ulva spp.; thus, gametes may develop into gametophytes (1 N) or parthenosporophytes (2 N). This study demonstrates that water motion has strong effects upon algal reproduction, but that the effects may vary between species, possibly due to their different life histories.Communicated by J.P. Grassle, New Brunswick