Letter from Andrew Carnegie to John Muir, 1913 Nov 6.

To my fellow ScotJohn Muirwith admirationAndrew CarnegieNov 6 1913Nov 61913After reading your charming story of Boyhood & Youth05603 ANDREWCARNEGIEHOW I SERVED MY APPRENTICESHIP AS A BUSINESS MA

Assessment and classification of a modified urban stream: Schneider Creek, Kitchener, Ontario

This study has produced an assessment framework and classification designed specifically for urban modified streams. While many stream assessment frameworks do exist, most are designed for natural streams and as such have no provision for characteristics of urban streams such as concrete channelization, storm drains, and urban debris. Building upon previous assessment and classification schemes, both urban and natural, this framework satisfies this need. It strengths lie in its user-friendly, visual-based approach to assessment by employing representative photographs and qualitative information to aid the user. A total of ten variables were employed that are scaled on a spectrum of categories, each differentiated by the number of points assigned. Once the assessment is completed, the scores are summed and the result is placed in one of five classification categories, ranging from Extreme Modification to Near Natural. This framework was tested on a heavily modified watershed, Schneider Creek, located in Kitchener, a fast urbanizing Census Metropolitan Area (CMA) approximately 100 km Southwest of Ontario’s capital of Toronto. This framework was tested in two different capacities on fifty-seven 100 metre segments throughout the watershed: 1) in the laboratory using aerial photographs and GIS layers, and 2) in the field. A major objective of the study was to determine if urban characteristics of streams could be accurately detected from a remotely sensed image and GIS data. It was discovered that only three variables, Channel Alteration, Riparian Width, and Type of Riparian Vegetation could be accurately detected from a geomatics database, with 75-87% average accuracy across all categories. It is thought that these variables were most accurate because they were ‘macro’ variables that could be seen clearly from above and were relatively static (did not change rapidly over time). Variables that were most difficult to detect were Bank Stability and Sediment Deposition. Variables such as these were thought to be ‘micro’ variables that were difficult to see from above and were constantly changing and therefore required fieldwork to detect accurately. It is suggested that for stream assessments, a combination of laboratory and fieldwork is best. Another major objective was to map the various channel types from the classification throughout the watershed. The purpose of this exercise was to generate an overview of creek modification and reveal any areas of concern. As expect, the most extremely modified sections were clustered around the heart of downtown Kitchener where industrial, commercial, and residential landuse is well established. This is an area of concern because it appears that concrete channelized sections are causing erosion in the southern sections of Schneider Creek via increased water velocity. Other areas of concern include various point sources of pollution and the rapidly urbanizing southwestern portion of the watershed. Various best management practices (BMPs) were suggested for these areas, but these are only short-term fixes. This study calls for greater public awareness of Schneider Creek and all watersheds, and it is suggested that the most effective way to accomplish this is through the power of maps, spatial thinking, and importance of viewing watersheds as dynamic systems

The Formation and Properties of Diphenyl Sulphide and Some of Its Derivatives

The therapeutic value of the diaryl sulphides has been a subject of much recent investigation. The halogen derivatives, especially iodine, or diphenyl-sulphide, have been carefully studied. The purpose of this work is not to study the therapeutic value of the diaryl sulphides, but to study some of the methods of preparation, and to determine the physical constants of a few of the compounds. Further, to study the relationship that exists between the diphenyl sulphides and the diphenyl ethers will be a part of this task

Maximizing precision over extended unambiguous range for TOF range imaging systems

The maximum unambiguous range for time-of-flight range imaging systems is inversely proportional to the chosen modulation frequency. However, increasing the unambiguous range by decreasing the modulation frequency will generally also degrade the range measurement precision. We describe a technique that significantly extends the range of a time-of-flight imaging system without compromising range precision. This is achieved by employing two modulation frequencies simultaneously. The chosen frequencies can be a combination of high and low frequency, or two similarly high frequencies. In this paper we present experimental results comparing single frequency; dual high and low frequency; and dual high frequency operation and demonstrate that range precision need not be appreciably compromised to achieve an extended unambiguous range

Characterization of modulated time-of-flight range image sensors

A number of full field image sensors have been developed that are capable of simultaneously measuring intensity and distance (range) for every pixel in a given scene using an indirect time-of-flight measurement technique. A light source is intensity modulated at a frequency between 10–100 MHz, and an image sensor is modulated at the same frequency, synchronously sampling light reflected from objects in the scene (homodyne detection). The time of flight is manifested as a phase shift in the illumination modulation envelope, which can be determined from the sampled data simultaneously for each pixel in the scene. This paper presents a method of characterizing the high frequency modulation response of these image sensors, using a pico-second laser pulser. The characterization results allow the optimal operating parameters, such as the modulation frequency, to be identified in order to maximize the range measurement precision for a given sensor. A number of potential sources of error exist when using these sensors, including deficiencies in the modulation waveform shape, duty cycle, or phase, resulting in contamination of the resultant range data. From the characterization data these parameters can be identified and compensated for by modifying the sensor hardware or through post processing of the acquired range measurements

Characterizing an image intensifier in an full-field range image system

We are developing a high precision full-field range imaging system. An integral component in this system is an image intensifier, which is modulated at frequencies up to 100 MHz. The range measurement precision is dictated by the image intensifier performance, in particular, the achievable modulation frequency, modulation depth, and waveform shape. By characterizing the image intensifier response, undesirable effects can be observed and quantified with regards to the consequence on the resulting range measurements, and the optimal operating conditions can be selected to minimize these disturbances. The characterization process utilizes a pulsed laser source to temporally probe the gain of the image intensifier. The laser is pulsed at a repetition rate slightly different to the image intensifier modulation frequency, producing a continuous phase shift between the two signals. A charge coupled device samples the image intensifier output, capturing the response over a complete modulation period. Deficiencies in our measured response are clearly identifiable and simple modifications to the configuration of our electrical driver circuit improve the modulation performance

Full field image ranger hardware

We describe the hardware designed to implement a full field heterodyning imaging system. Comprising three key components - a light source, high speed shutter and a signal generator - the system is expected to be capable of simultaneous range measurements to millimetre precision over the entire field of view. Current modulated laser diodes provide the required illumination, with a bandwidth of 100 MHz and peak output power exceeding 600 mW. The high speed shutter action is performed by gating the cathode of an image intensifier, driven by a 50 Vpp waveform with 3.5 ns rise and fall times. A direct digital synthesiser, with multiple synchronised channels, provides high stability between its outputs, 160 MHz bandwidth and tuning of 0.1 Hz

Development and characterisation of an easily configurable range imaging system

Range imaging is becoming a popular tool for many applications, with several commercial variants now available. These systems find numerous real world applications such as interactive gaming and the automotive industry. This paper describes the development of a range imaging system employing the PMD-19 k sensor from PMD technologies. One specific advantage of our system is that it is extremely customisable in terms of modulation patterns to act as a platform for further research into time-of-flight range imaging. Experimental results are presented giving an indication of the precision and accuracy of the system, and how modifying certain operating parameters can improve system performance

Image intensifier characterization

An image intensifier forms an integral part of a full-field image range finder under development at the University of Waikato. Operating as a high speed shutter with repetition rates up to 100 MHz, a method is described to characterise the response, both temporally and spatially, of the intensifier in order to correct for variations in the field of view and to optimise the operating conditions. A short pulse of visible light is emitted by a laser diode, uniformly illuminating the image intensifier, while a CCD camera captures the output from the intensifier. The phase of the laser pulse is continuously varied using a heterodyne configuration, automatically producing a set of samples covering the modulation cycle. The results show some anomalies in the response of our system and some simple solutions are proposed to correct for these

Characterizing an image intensifier in an full-field range image system

We are developing a high precision full-field range imaging system. An integral component in this system is an image intensifier, which is modulated at frequencies up to 100 MHz. The range measurement precision is dictated by the image intensifier performance, in particular, the achievable modulation frequency, modulation depth, and waveform shape. By characterizing the image intensifier response, undesirable effects can be observed and quantified with regards to the consequence on the resulting range measurements, and the optimal operating conditions can be selected to minimize these disturbances. The characterization process utilizes a pulsed laser source to temporally probe the gain of the image intensifier. The laser is pulsed at a repetition rate slightly different to the image intensifier modulation frequency, producing a continuous phase shift between the two signals. A charge coupled device samples the image intensifier output, capturing the response over a complete modulation period. Deficiencies in our measured response are clearly identifiable and simple modifications to the configuration of our electrical driver circuit improve the modulation performance