title: A calibrated dual-port acoustic Vector Network Analyser

authors: MacDonell, Marcus Scott Glengarry

subjects: VNA

abstract: The Vector Network Analyzer (VNA) is a workhorse in electrical engineering, and has been refined over the last fifty years to offer many advantages. This technology is continually expanding and branching into other fields including optics. This thesis presents the design and calibration of an Acoustic Vector Network Analyzer (AVNA), which represents further adaptation of this technology into other engineering fields. This goal requires several developments; a repeatable acoustic waveguide flange/joint, a calibration method(s), calibration standards, and calibration verification.

The hardware that has been developed is used as an accessory to an existing commercial VNA mainframe (Agilent-4395A) and a retrofitted test-set (HP87511A) that now hosts connectivity for our ``measurement heads'' containing the acoustic directional couplers. Directional couplers are the fundamental technology that allows for Vector Network Analysis, the acoustic variant has an operational range of a little more than an octave and sufficient directionality for calibration. The coupler is a branch waveguide coupler and to enable reliable and repeatable connection has been equipped with a flange system. This flange system has alignment pins and O-rings to ensure proper sealing and repeatability. Several materials were used with additive manufacturing techniques to create couplers and waveguide sections, each with its own advantages. Titanium (Ti64) offered the best usability and reliability, while plastic offered better repeatability.

Calibration was a major advance in the VNA and one that popularized the instrument. The calibration's performance is limited by the repeatability of flanged joints. This is because several measurements are required to produce a linear system of equations, therefore this system contains within it the variation of the flange joints. 

Developing a calibration method is the crux in realizing the aim of an Acoustic VNA. This thesis presents a set of five measurements and two competing algorithms that can be used to implement calibration. The analytical and numerical methods presented both have distinct advantages and disadvantages. The five measurements are performed with proposed calibration standards. A ``Thru'', ``Reflect'' and ``Match'' standard are required. The ``Match'' standard is provided by a sliding load, the sliding load has been previously used as part of an acoustic calibration. To verify the operation of the calibrated instrument verification measurement was performed using a passive, asymmetrical, reciprocal device (PARD).

text: A calibrated dual-port acoustic Vector Network Analyser The Vector Network Analyzer (VNA) is a workhorse in electrical engineering, and has been refined over the last fifty years to offer many advantages. This technology is continually expanding and branching into other fields including optics. This thesis presents the design and calibration of an Acoustic Vector Network Analyzer (AVNA), which represents further adaptation of this technology into other engineering fields. This goal requires several developments; a repeatable acoustic waveguide flange/joint, a calibration method(s), calibration standards, and calibration verification.

The hardware that has been developed is used as an accessory to an existing commercial VNA mainframe (Agilent-4395A) and a retrofitted test-set (HP87511A) that now hosts connectivity for our ``measurement heads'' containing the acoustic directional couplers. Directional couplers are the fundamental technology that allows for Vector Network Analysis, the acoustic variant has an operational range of a little more than an octave and sufficient directionality for calibration. The coupler is a branch waveguide coupler and to enable reliable and repeatable connection has been equipped with a flange system. This flange system has alignment pins and O-rings to ensure proper sealing and repeatability. Several materials were used with additive manufacturing techniques to create couplers and waveguide sections, each with its own advantages. Titanium (Ti64) offered the best usability and reliability, while plastic offered better repeatability.

Calibration was a major advance in the VNA and one that popularized the instrument. The calibration's performance is limited by the repeatability of flanged joints. This is because several measurements are required to produce a linear system of equations, therefore this system contains within it the variation of the flange joints. 

Developing a calibration method is the crux in realizing the aim of an Acoustic VNA. This thesis presents a set of five measurements and two competing algorithms that can be used to implement calibration. The analytical and numerical methods presented both have distinct advantages and disadvantages. The five measurements are performed with proposed calibration standards. A ``Thru'', ``Reflect'' and ``Match'' standard are required. The ``Match'' standard is provided by a sliding load, the sliding load has been previously used as part of an acoustic calibration. To verify the operation of the calibrated instrument verification measurement was performed using a passive, asymmetrical, reciprocal device (PARD).

year: 2022

title: OpinionZoom, a modular tool to explore tourism opinions on the Web

authors: Marrese-Taylor, Edison

abstract: In this paper, we propose OpinionZoom, a modular software that helps users in an easy manner to understand the vast amount of tourism opinions disposed all over the Web. We also successfully implemented and tested OpinionZoom, encompassing the situation of the tourism industry in Los Lagos, also known as the Lake District, in Chile. Results showed the effectiveness of the designed proposal when applied to solving this specific industry's issues.

text: OpinionZoom, a modular tool to explore tourism opinions on the Web In this paper, we propose OpinionZoom, a modular software that helps users in an easy manner to understand the vast amount of tourism opinions disposed all over the Web. We also successfully implemented and tested OpinionZoom, encompassing the situation of the tourism industry in Los Lagos, also known as the Lake District, in Chile. Results showed the effectiveness of the designed proposal when applied to solving this specific industry's issues.

year: 2013-12-01

title: The Indigenous Exchange Forum: transitions in mine closure

authors: Holcombe, Sarah

abstract: “The Indigenous Exchange Forum: transitions in mine closure” was held on 2–3 November 2021 over Zoom, hosted by the Centre for Social Responsibility in Mining (CSRM) in the Sustainable Minerals Institute (SMI), at The University of Queensland.
The Forum aimed to affirm, connect, and elevate the voices of First Nations leaders and interested community members impacted by mining and mine closure. In doing so, we hoped to begin to build an international network across these Indigenous communities, to enable the sharing of experiences, struggles, and sentiments in relation to mine site transition and mine-related impacts on their lands.
The intent was to recognise each other’s unique cultural position and the impact of mining and mine closure through lessons learned: first with each other and then with industry.
The Forum had a strong foundation of reciprocity. The objective was:
•To provide an independent and culturally safe space to facilitate the connectionbetween First Nations peoples, whose customary lands have been impacted bymining.
•To position First Nations voices individually and collectively in a shared learningjourney full of experiences and lessons learned through online network exchange.
•To facilitate knowledge exchange and elevate the connectivity between Canadian,Australian, and Aotearoa (New Zealand) First Nations regarding impacts, issues, andinnovative ideas and practices in response to mine site transitions and mine closure.

text: The Indigenous Exchange Forum: transitions in mine closure “The Indigenous Exchange Forum: transitions in mine closure” was held on 2–3 November 2021 over Zoom, hosted by the Centre for Social Responsibility in Mining (CSRM) in the Sustainable Minerals Institute (SMI), at The University of Queensland.
The Forum aimed to affirm, connect, and elevate the voices of First Nations leaders and interested community members impacted by mining and mine closure. In doing so, we hoped to begin to build an international network across these Indigenous communities, to enable the sharing of experiences, struggles, and sentiments in relation to mine site transition and mine-related impacts on their lands.
The intent was to recognise each other’s unique cultural position and the impact of mining and mine closure through lessons learned: first with each other and then with industry.
The Forum had a strong foundation of reciprocity. The objective was:
•To provide an independent and culturally safe space to facilitate the connectionbetween First Nations peoples, whose customary lands have been impacted bymining.
•To position First Nations voices individually and collectively in a shared learningjourney full of experiences and lessons learned through online network exchange.
•To facilitate knowledge exchange and elevate the connectivity between Canadian,Australian, and Aotearoa (New Zealand) First Nations regarding impacts, issues, andinnovative ideas and practices in response to mine site transitions and mine closure.

year: 2022