Commissioning and verification of compressed air yield on the hydraulic air compressor demonstrator

The completion of the hydraulic air compressor (HAC) demonstrator at Dynamic Earth in Sudbury, Ontario marks the beginning of a series of research activities to increase the efficiency of compressed air production and build confidence in future commercial applications. Before any proper experiments could be conducted on the HAC Demonstrator a series of commissioning activities and testing was completed to i) calibrate the instruments, ii) check and understand losses, and iii) verify, or otherwise, some of the assumptions made during the system design. The practical work associated with this master’s thesis included the development of a human machine interface (HMI) to allow for automated control of the HAC. Instrumentation and control equipment was installed and routed to a control panel providing conditioned power and routes for signals. Within the control panel, these are digitised and transmitted using TCP/ IP/ MODBUS protocol, operating over a TopServer (Software toolbox, 2009) OPC backbone. The OPC Client toolbox in MATLAB was adopted to interface with the OPC Server, and MATLAB’s App Designer adopted for authoring the HMI. All I/O functionality is thus routed to MATLAB in which a PID control loop was established between the HAC separator water level and the HAC’s compressed air motorized globe valve. Thus, a reliable, flexible, scientific control interface and data storage infrastructure was established for this novel compression plant as part of the master’s work. The HAC Demonstrator can now effectively run a variety of experiments while recording a wide range of data for analysis. To date, a series of 90 benchmark tests for compressor performance have been completed in a systematic manner on the demonstrator to create a database of real HAC operating conditions. This thesis thus represents the first formal publication of the HAC Demonstrator’s complete performance under the baseline operating conditions. Previous predictions of the compressed air yield and efficiency of a HAC of this size have been made by Millar (2014), upgraded to weakly couple solubility loss by Pavese et al. (2016) and refined using Young’s (2017) detailed coupling of solubility and psychrometric phenomena. The predictions made by these models have been tested. The 1D hydrodynamic solubility models also predicted a small beneficial ‘airlift’ effect on compressor performance, due to exsolution of formerly dissolved compressed gas, that has also been reported upon. One unexpectedly important factor that has been found to affect HAC performance that was not anticipated in any of the models included the absolute surface roughness of rubber lined pipe, in comparison to that of bare steel pipe. High precision experiments are reported upon that have produced reliable values for absolute surface roughness for rubber lining materials, that have now been adopted in the HAC models, and may be adopted more widely too. The occurrence of detrainment, water jet-free fall and air re-entrainment is speculated upon as the source of previously unreported loss in the air-water mixing process, based on pressure profiling observations undertaken over the complete performance envelope of the Dynamic Earth HAC Demonstrator.Science (MASc) in Natural Resources Engineerin

Integrin α8β1 regulates adhesion, migration and proliferation of human intestinal crypt cells via a predominant RhoA/ROCK-dependent mechanism

Background. Integrins are transmembrane αβ heterodimer receptors that function as structural and functional bridges between the cytoskeleton and ECM (extracellular matrix) molecules. The RGD (arginine-glycine-aspartate tripeptide motif)-dependent integrin α8β1 has been shown to be involved in various cell functions in neuronal and mesenchymal-derived cell types. Its role in epithelial cells remains unknown

Teacher Excellence: Students' and Teachers' Perceptions and the Influence of Leadership

The extent to which students' and teachers' perceptions agree about excellent teachers has implications for educational philosophy, training, and leadership practices. Teacher excellence depends teachers are rarely sought. Experts write about what should be taught, how it should be taught, but those who are being taught have little voice. Learning what traits and practices exemplify excellent teachers would enable us to capitalize on those traits and train teachers to use those practices. The intent of this study was to learn what teacher excellence was like for students and teachers. From those who have experienced teacher excellence from both sides of the desk, particular characteristics and practices were identified as important or essential. This study employed interviews of high school seniors and teachers. Questions were related to a district's contract appendix, literature about best practices, career interest and personality inventories, and from discussions with students and teachers. Fourteen student interviews and fourteen teacher interviews were transcribed. Ten of each category were distributed to a team of coders, by the researcher. Using the Consensual Qualitative Research method, coders and researcher placed participants' responses in domains, categorized them, and with an auditor's guidance, searched for those that were typical and those that were variant. Discarded interviews were to be replaced by other interviews until stability occurred. The team sought patterns among the participants' responses. Finally, the researcher analyzed the data and drew and reported conclusions. Students described excellent teachers who connected with their students on a social, emotional level. Examples of student's responses were instances of a teacher approaching a student to ask if the student needed assistance, opening classrooms at non-instructional times to provide a welcome setting in which to relax until the next class, visiting the student at his workplace, and attending students' performances. Teachers described the excellent teacher's relationship with students as a teacher who might attend performance events, but might also insist the student come in for extra help or encourage the student to put forth greater effort. The emphasis the teachers placed on rapport building between teacher and student was based more on academic than on emotional support. The role that teachers were described by students as performing was that of nurturer or counselor, whereas the role the teachers' description described was that of facilitator and coach

Stability of Volatile Sulfur Compounds (VSCS) in sampling bags - Impact of temperature

Volatile sulfur compounds (VSCs) are a major component of odorous emissions that can cause annoyance to local populations surrounding wastewater, waste management and agricultural practices. Odour collection and storage using sample bags can result in VSC losses due to sorption and leakage. Stability within 72 hour storage of VSC samples in three sampling bag materials (Tedlar, Mylar, Nalophan) was studied at three temperatures: 5, 20, and 30°C. The VSC samples consisted of hydrogen sulfide (H2S), methanethiol (MeSH), ethanethiol (EtSH), dimethyl sulfide (DMS), tertbutanethiol (t-BuSH), ethylmethyl sulfide (EMS), 1-butanethiol (1-BuSH), dimethyl disulfide (DMDS), diethyl disulfide (DEDS), and dimethyl trisulfide (DMTS). The results for H 2S showed that higher loss trend was clearly observed (46-50% at 24 hours) at 30 W C compared to the loss at 5°C or 20°C (of up to 27% at 24 hours) in all three bag materials. The same phenomenon was obtained for other thiols with the relative recoveries after a 24 hour period of 76-78% at 30°C and 80-93% at 5 and 20°C for MeSH; 77-80% at 30°C and 79-95% at 5 and 20°C for EtSH; 87-89% at 30°C and 82-98% at 5 and 20°C for t-BuSH; 61-73% at 30°C and 76-98% at 5 and 20°C for 1-BuSH. Results for other sulfides and disulfides (DMS, EMS, DMDS, DEDS) indicated stable relative recoveries with little dependency on temperature (83-103% after 24 hours). DMTS had clear loss trends (with relative recoveries of 74-87% in the three bag types after 24 hours) but showed minor differences in relative recoveries at 5, 20, and 30°C. © IWA Publishing 2013

Off-gas Nitrous Oxide monitoring for nitrification aeration control

Effective control of nitrification processes employed at municipal wastewater treatment plants is essential for maintaining process reliability and minimizing environmental impacts and operating costs. While a range of process control strategies are available, they share a dependence on invasive liquid phase monitoring and are based on a periphery understanding of the metabolic status of the processes being controlled. Utilization of off-gas nitrous oxide (N2O) monitoring as a real-time indicator of the process metabolic status is a novel process control concept with the potential to address these concerns. This thesis details the development and evaluation of an off-gas N2O stress response based control technique. Examination of the stress response relationship demonstrated that it met the majority of the criteria of interest for process control. A simple feedback aeration control strategy was developed and evaluated through process simulation to determine the feasibility of implementation, cost effectiveness and associated environmental benefits. The off-gas N2O based control strategy provided better matching between aeration supply and metabolic demand, allowing the process to be maintained at the desired operating setpoints and avert nitrification failure. Performance was demonstrated to be similar to dissolved oxygen based feedback aeration control, although slightly more efficient at reduced dissolved oxygen concentrations. A technical, economic and environmental evaluation indicated that aeration control based on non-invasive off-gas N2O monitoring is technically feasible and has the potential to offer significant environmental and economic benefits including reductions in operating costs and process capital investment, as well as improved effluent compliance and reductions in emissions of gaseous pollutants including greenhouse gases. Overall, while off-gas N2O monitoring based aeration control techniques have the potential to provide significant economic and environmental benefits, a number of research questions remain to be answered. Future work in the form of long-term field trials is required to address these issues and allow quantification of economic and environmental benefits

Factors affecting the adsorption of gaseous environmental odors by activated carbon: A critical review

<p>Activated carbon has a long history of application to abate gaseous environmental odors; however, design and operating decisions are primarily based on empirical relations and pilot testing, with limited use of fundamental mechanistic knowledge. To support improved abatement outcomes, environmental odorant adsorption was reviewed. While influenced by a range of adsorbate and adsorbent properties and process operating conditions, information about their impacts is often limited or unavailable. Current research has focused on volatile sulfur compounds, with lesser focus on volatile organic compounds and volatile nitrogen compounds. Even within volatile sulfur compounds, most work has focused on hydrogen sulfide and the full range of reduced sulfur compounds (important environmental odorants) remain to be studied. The current narrow window of knowledge does not reflect the complexity of environmental odorants and is limiting development and systematic application of this technology. It has been demonstrated that single component adsorbent characterization does not reflect the adsorption of the complex mixture of odorants and non-odorous compounds that make up environmental odor emissions. Studies to explore adsorption competition in multi-compound systems and develop methods/guidance to account for this in abatement system selection and design are required to achieve cost effective and reliable outcomes.</p