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- OPEN ACCESS
- R. Gunabalan,
- P. Sanjeevikumar,
- Frede Blaabjerg,
- Patrick W. Wheeler,
- Olorunfemi Ojo, and
- Ahmet H. Ertas
This paper presents the characteristic behavior of direct vector control of two induction motors with sensorless speed feedback having the same rating parameters, paralleled combination, and supplied from a single current-controlled pulse-width-modulated voltage-source inverter drive. Natural observer design technique is known for its simple construction, which estimates the speed and rotor fluxes. Load torque is estimated by load torque adaptation and the average rotor flux was maintained constant by rotor flux feedback control. The technique’s convergence rate is very fast and is robust to noise and parameter uncertainty. The gain matrix is absent in the natural observer. The rotor speed is estimated from the load torque, stator current, and rotor flux. Under symmetrical load conditions, the difference in speed between two induction motors is reduced by considering the motor parameters as average and difference. Rotor flux is maintained constant by the rotor flux control scheme with feedback, and the estimation of rotor angle is carried out by the direct vector control technique. Both balanced and unbalanced load conditions are investigated for the proposed AC motor drive system. Experimental results presented in this paper show good agreement with the theoretical formulations. - OPEN ACCESSThis short communication focuses on exploiting the inherent advantages of discrete wavelet transformation (DWT) as a diagnostic tool for post-processing and for identifying the faults that occur in the standard high-voltage direct-current (HVDC) transmission network. In particular, a set of investigations are developed and examined for single-line-to-ground fault on the generation and on the load side converter, and DC-link fault. For this purpose, a standard 12-pulse line-commutated converter (LCC)-HVDC transmission network along with the DWT algorithm is numerically modeled in the MATLAB/PLECS simulation software. Furthermore, in this paper, a set of designed faulty conditions are predicted using the output of DWT and the results of numerical simulation are presented. Results are in good agreement with expectations to prove that DWT is an effective tool for fault diagnostics.
- OPEN ACCESSMicro-trenching is an innovative and discreet utility installation method that includes the creation of a narrow trench to lay cable or conduit in the ground. To investigate the functionality and durability of micro-trenching in cold regions, two micro-trenching technologies were employed and monitored over the course of two winters in a parking lot in Edmonton, Alberta, Canada. During construction, productivity rate and generated waste material were studied. The installation’s physical integrity and optical performance were also evaluated during the monitoring period. Physical integrity was assessed by monitoring the conduit location using ground-penetrating radar (GPR), and an optical time-domain reflectometer (OTDR) test was conducted to determine attenuation in performance. Results indicated that the installation experienced undesirable upward and downward movements in sections with high traffic load, which may be prevented with a more effective reinstatement method. However, the fiber’s optical performance was not affected.
- OPEN ACCESSA distributed optical strain-sensing technique is presented as a solution for measuring the strain distribution along ground support members used in tunnelling and mining works. The technique employs a Rayleigh optical frequency domain reflectometry technology, which measures strain at a spatial resolution of 0.65 mm along the length of a standard optical fiber. A rationale for selecting this technology as a potential monitoring technique for ground support elements over alternative commercially available technologies is discussed. The development of a technique to couple optical fiber sensors with rock bolt, umbrella arch, and cable bolt support members is also demonstrated. A robust laboratory investigation of such optically instrumented support members demonstrated the capability of the technique to capture the expected in situ support behaviour in the form of coaxial, lateral, and shear loading arrangements as would be anticipated in the field. Moreover, the micro-scale data obtained by this optical sensing technique are shown to provide unprecedented insight into the local/micro-scale geomechanistic complexities associated with the bearing capacity of ground support members, especially when compared with data obtained by discrete strain-sensing technologies.
- OPEN ACCESSThe Canadian Environmental Protection Act (CEPA) enables the Minister of Environment and Climate Change to develop policy to curtail international air pollution. However, regional air pollution generated during the manufacturing of products outside of Canada is not addressed in CEPA. Using cement manufacturing in China as a case study, three policy options were devised to manage export-based regional air pollution. The options investigated included Policy 1—an open border with direct support for domestic cement manufacturers, Policy 2—a restricted border with no support for domestic cement manufacturers, and Policy 3—a selective border with partial support for domestic cement manufacturers. An analytic hierarchy process, in conjunction with the three actionable solidarities of cultural theory, was applied to the policy options and their supporting mechanisms. Results indicated that Policy 3 was strongly favoured (52.5%), followed by Policy 2 (33.4%), with Policy 1 being the least favoured (14.2%). Regarding policy mechanisms, a verification process was preferred by all three solidarities. From the standpoint of a universal approach to trade it is recommended that an air quality agreement between China and Canada under CEPA be established with a framework to eventually incorporate environmental production declarations. With respect to cement exports, it is recommended that manufacturers in China provide emissions intensities and winter smog assessments.
- OPEN ACCESS
- Lori E.A. Bradford,
- Tim Vogel,
- Karl-Erich Lindenschmidt,
- Kerry McPhedran,
- Graham E.H. Strickert,
- Terrence A. Fonstad, and
- Lalita A. Bharadwaj
There is movement in engineering fields and in Indigenous communities for enhancement of local participation in the design of community infrastructure. Inclusion of community priorities and unique cultural, spiritual, and traditional values harmonize the appearance, location, and functionality of developments with the social and cultural context in which they are built and contribute to holistic wellness. However, co-design processes that align community values and the technical needs of water facilities are difficult to find. A scoping review was conducted to explore the state of knowledge on co-design of water infrastructure in Indigenous Canada to build a knowledge base from which practices and processes could emerge. The scoping results revealed that articles and reports emerged only in recent years, contained case studies and meta-reviews with primary (qualitative) data, and involved community members in various capacities. Overall, 13 articles were reviewed that contributed to understanding co-design for water infrastructure in Indigenous Canada. Barriers to co-design included funding models for Indigenous community infrastructure, difficulties in engineers and designers understanding Indigenous worldviews and paradigms, and a lack of cooperation among stakeholders that contribute to ongoing design failures. A working definition of co-design for Indigenous water infrastructure is presented. - OPEN ACCESSThis paper outlines the testing and monitoring procedure of a scale model Warren truss constructed of 2 inch × 4 inch (38 mm × 89 mm) members and bolted connections within a laboratory environment. Several forms of deflection monitoring and strain monitoring instrumentation were utilized throughout this laboratory testing phase of a longer-term research program. Instruments included: an automatic total station, linear variable differential transducers, light detection and ranging, electric strain gauges, and distributed optical fibre sensors. The distributed point load-testing regime included two configurations: (i) the original truss configuration and (ii) the installation of intermediate columns beneath the truss. Objectives of this phase included identifying instrument capabilities, limitations, and overall reliability/effectiveness with respect to representing the behaviour of the truss system. In addition, members of interest and critical monitoring locations along the Warren truss were determined. The purpose of this laboratory endeavour was to determine an optimized structural-health monitoring program prior to implementation in a heritage timber Warren truss structure within the infrastructure inventory of the Department of National Defence (DND). An options analysis of monitoring techniques was conducted whereby the effectiveness of each instrumentation type was evaluated according to relevant metrics/factors to determine an effective monitoring technique for this heritage building and other similar DND truss structures.
- OPEN ACCESSBased on the Mindlin solution, this paper considers the influence of factors such as the non-uniform distribution of additional thrust of the cutter head influenced by lateral earth pressure in shield excavation, the non-uniform distribution of friction of shield shell influenced by soil softening and slurry spreading, and the non-uniform distribution of grouting pressure influenced by slurry spreading on the horizontal displacement of soil. The existing prediction formula is revised and verified by engineering examples. It is found that: affected by the shield construction disturbance force, the horizontal displacement behind the excavation surface is larger than that in front of the excavation surface, and the peak value of the horizontal displacement appears around the tunnel axis; through the verification of engineering case, when calculating the horizontal displacement in front of the excavation surface, the calculation results of both the modified formula and the original formula are in good agreement with the measured values, which can reflect the change trend of the measured horizontal displacement; when calculating the horizontal displacement behind the excavation surface, the calculation result of the existing formula has a great error due to the assumption of uniform distribution of disturbance force, which is different from the law of the measured result; the calculation result of the modified prediction formula is obviously in better agreement with the measured deformation value, and the error is smaller, which is more in line with the engineering reality.
- OPEN ACCESSMalaria is a life-threatening parasitic disease transmitted to humans by infected female Anopheles mosquitoes. Early and accurate diagnosis is crucial to reduce the high mortality rate of the disease, especially in eastern Indonesia, where limited health facilities and resources contribute to the effortless spread of the disease. In rural areas, the lack of trained parasitologists presents a significant challenge. To address this issue, a computer-aided detection (CAD) system for malaria is needed to support parasitologists in evaluating hundreds of blood smear slides every month. This study proposes a hybrid automated malaria parasite detection and segmentation method using image processing and deep learning techniques. First, an optimized double-Otsu method is proposed to generate malaria parasite patch candidates. Then, deep learning approaches are applied to recognize and segment the parasites. The proposed method is evaluated on the PlasmoID dataset, which consists of 468 malaria-infected microscopic images containing 691 malaria parasites from Indonesia. The results demonstrate that our proposed approach achieved an F1-score of 0.91 in parasite detection. Additionally, it achieved better performance in terms of sensitivity, specificity, and F1-score for parasite segmentation compared to original semantic segmentation methods. These findings highlight the potential of this study to be implemented in CAD malaria detection, which could significantly improve malaria diagnosis in resource-limited areas.
- OPEN ACCESSA boil water advisory (BWA) informs the public that there is an increased level of risk associated with their water and that they should boil it before consuming. Studies show that small communities in Canada are particularly likely to experience repeat and long-term BWAs. Climate change has led to changes in precipitation and temperature patterns, leading to region-specific impacts such as increased frequency, severity, or variance in floods, forest fires, droughts, freezing rain, and sea water intrusion. Academic and non-academic “grey” literature was reviewed to establish the most likely impacts of climate change on water treatment and infrastructure. Anonymized data from public drinking water systems in Canada was analyzed to determine the most common causes of BWAs between 2005 and 2020. Most BWAs reported were related to breakdowns/malfunctions along the distribution, though inadequate disinfection residual and turbidity or coliforms in the treated water were also common. Furthermore, statistical analysis of the data showed seasonal trends in some of these parameters. The results of this study suggest that increased precipitation, flooding, permafrost degradation, and forest fires are likely to have significant impacts on water safety in Canada.Highlights:Climate change effects are expected to worsen many current water challenges.Climate change will disproportionately impact small, rural, and remote water utilities.Water distribution systems are the main source of water safety risk in Canada.Groundwater-supplied systems experience a disproportionate number of BWAs.Seasonal trends in BWA reasons provide opportunities for targeted mitigation.
- OPEN ACCESS
A simulation-based optimization method for emergency evacuation induced by gas pipeline leakage risk
Long-distance gas pipelines with large diameter and high pressure, on which a leakage induces gas diffusion or fire explosion, may result in major influence to nearby buildings and residents. Safety and rapid evacuation of potentially affected people is a top priority. To analyze the affected areas by disasters and improve evacuation efficiency of the affected areas, this study presents a simulation-based optimization method for emergency evacuation induced by gas leakage risk. First, the influence radii of different leakage accidents were calculated based on damage criteria and the evacuation radii around the accidents were determined considering the panic psychology. The number of evacuees and their spatial distribution were calculated. Secondly, an evacuation simulation model for affected communities based on the multi-agent system was established to analyze the evacuation process of residents. Finally, the optimal design method and strategies for community evacuation were proposed. Responsibility areas of organized evacuation service for community exits were determined. The results showed that the evacuation times of the two communities A and C were reduced by 10% and 24%, which indicates organized evacuation is more efficient than unorganized evacuation. The selection of community exits is more balanced. Its rationality of the proposed method was verified by the comparison of evacuation simulation. - OPEN ACCESSUniversity campus networks need wired (ethernet) and dense wireless fidelity networks that have devices like access points, switches, and routers that are always turned on. Consequently, they generate two important problems: the energy bill and the influence of carbon dioxide into the atmosphere. Energy savings are the solution to those problems. There are several proposals to augment the energy savings separately in ethernet and wireless fidelity, but there is no integrated method to simultaneously reduce them in both parts of the networks. Our novel method combines idle cycling and machine learning techniques to efficiently obtain energy savings in both parts of the network simultaneously. We categorize network devices into two groups: (a) those that are always turned on and (b) those that can be dynamically turned on or off based on network performance. We formulated two algorithms that decide when to turn on and off access points. We use Ward's machine learning hierarchical clustering technique to optimize the energy savings of our model in the network of the Unidades Tecnológicas de Santander (Bucaramanga, Colombia). We showed that energy savings of 21.5 kWh per day are possible. The success of the model in this context highlights its potential to achieve substantial energy savings.