48080 research outputs found
Sort by
Large scale grouting in mining
No full textThis paper presents the concept of grouting using oilfield scale hydrofracture pumping systems to treat faulted and permeable rock masses to seal them against water movement and to consolidate them. The reasoning behind this is that such systems are readily available in many locations and offer much higher flow at high pressures over the small scale grouting systems that are typically used in mining. The potential exists to grout faulted rock masses so that mine de-watering pumping needs are minimised when the mine is developed. Filling pore spaces to displace water from the body of the rock mass will be more difficult but may be possible in some very porous formations.</p
Path optimisation for drill rigs: a step toward full automation in mining
No full textThe mining industry is advancing toward full automation, with drill and blast operations identified as critical bottlenecks in achieving this goal. Although some drilling tasks have been automated, key aspects, such as drilling rigs' programming and tramming (i.e., path planning), still rely on human input. This paper proposes an exact optimisation methodology to optimise drill rig paths by identifying the most efficient routes. The model evaluates multiple path planning scenarios to select the optimal path, showing a notable 64% reduction in total travelled distance compared to manual tramming in an application of a case study. Furthermore, the generated paths in this study align more closely with the physical constraints of drill rigs during tramming, enhancing operational feasibility and efficiency.</p
Impact of vanadium (V) content on in-situ oxidation, high temperature mechanical strength and tribological properties of Al<sub>0.5</sub>CrFeNiV<sub>x</sub> high entropy alloys
No full textIn this study, four vanadium (V) containing high entropy alloys (HEAs) Al0.5CrFeNiVx (x = 0.25, 0.5, 0.75, 1.0) were developed and investigated, in terms of examining the influence of V content on their microstructure, in-situ oxidation behavior, high temperature mechanical strength, and high temperature tribological performances. An increase in the V content causes precipitation of the Laves phase (VAl2) in the body-centered cubic (BCC) matrix. This structural transition increases the alloy hardness and compressive strength through solid solution strengthening, precipitation strengthening and grain refinement strengthening. When x is increased from 0.25 to 1, the maximum compressive strength increases from about 2476 to 3241 MPa at room temperature and from about 521 to 797 MPa at 700 °C, respectively. In-situ oxidation investigation reveals that a higher V content accelerates the oxidation and provides a direct evidence of vanadium oxides melting at 700 °C and thus forming the liquid oxide phases on the surface of HEAs. During high temperature tribological contact, the liquid oxide phases minimize the friction, allowing thicker and more complex oxide layers to form on the worn surface to improve the HEAs’ wear resistance. The findings in this work contribute to the development of novel HEAs with superior properties for potential applications that need outstanding mechanical strength, wear resistance, and thermal stability.</p
Understanding Patients' Perceptions of Social Support Features on Social Media and its Effects on Behaviour Change
No full textThe abstract for this item has not been populated.</p
How Accurate Are QM/MM Models?
No full textDespite the success and widespread use of QM/MM methods in modeling (bio)chemically important processes, their accuracy is still not well understood. A key reason is because these methods are ultimately approximations to direct QM calculations of very large systems, which are impractical to perform in most cases. We highlight recent progress toward the development of realistic model systems where it is possible to obtain full QM reference data to directly and systematically evaluate the effectiveness of different QM/MM generation schemes. These model systems are highly flexible and can be tailored to probe the sensitivity of a QM/MM model to different reaction types and simulation parameters such as pairing of QM and MM potentials, QM region size, and composition. It is envisaged that this strategy could be used to directly validate different QM/MM generation schemes and spur the development of more robust models in the future.</p
How many is enough? Justifying sample size in descriptive quantitative research
No full textBackgroundDescriptive quantitative researchers often use surveys to collect data about a group or phenomenon. Determining the required sample size in descriptive surveys can pose a challenge as there is no simple 'formula' by which to calculate an appropriate sample. However, when a sample is too small the study may fail to answer the research question and too many responses can create resource implications.AimTo explore considerations regarding the justification of adequate sample size in descriptive quantitative research.DiscussionSeveral considerations may assist quantitative descriptive researchers in examining the appropriateness and justification of sample size. Response rates can guide decision-making around the proportion of the target population who respond. Additionally, consideration of any validated tools, the spread or responses and types of analysis can guide sampling decisions.ConclusionThe strategies in this article provide a considered approach to justifying sample size in descriptive quantitative research. Factors such as response rates and analytical considerations provide a transparent means of justifying an adequate sample.Implications for practiceProviding clear justification for the sample size within descriptive quantitative research demonstrates a robust research approach and optimises resource use.</p
Effectiveness of case-based learning in comparison to alternate learning methods on learning competencies and student satisfaction among healthcare professional students: A systematic review
No full textTo evaluate the effectiveness of case-based learning (CBL) versus alternate learning methods on learning competencies and student satisfaction among healthcare students. A systematic search of the PubMed, SCOPUS, CINAHL, and Cochrane CENTRAL databases was conducted from database inception to December 31, 2021. The grey literature, Google Scholar, and hand searching were also conducted. The keywords used were "case-based learning,""case learning,""traditional learning,""problem-based learning,""simulation-based learning,""learning competenc∗,""competenc∗,""student satisfaction,""satisfaction,""medic∗,""dent∗,""nursing""pharmac∗,""students,""undergraduate,""postgraduate,"and "clerkship."Only studies comparing CBL methods with a control group or with an alternate learning method conducted on healthcare students were considered. The risk of bias was assessed independently by two reviewers. Data analysis was undertaken using RevMan 5.4. Twenty-two studies were included in the final review, of which 20 studies compared CBL with lecture-based learning (LBL) and two compared CBL with simulation-based learning. Pooled data demonstrated that critical thinking scores were significantly higher among those receiving CBL than those receiving LBL (standardized mean difference (SMD): 0.75, 95% confidence interval (95%CI): 0.21-1.29). Similarly, significantly greater scores for teamwork and communication were identified in the CBL group than in the LBL groups (SMD: 0.24; 95%CI: -0.19-0.66). However, no significant difference in knowledge and comprehension scores (SMD: 0.41; 95%CI: 0.20-0.62) and self-directed learning (SMD: 0.30; 95%CI: 0.10-0.49) was identified among those who received CBL compared to those who received LBL. Based on the results of this review, CBL has been identified as a superior teaching method as it significantly improves critical thinking, problem-solving, teamwork, and communication skills and enhances clinical skills development and student satisfaction. However, more rigorous RCTs are needed to underpin the available evidence.</p
Perceptions and Utilization of Registered Dietitian Nutritionists in Multiple Sclerosis Care: A Pilot Survey of Multidisciplinary Providers
No full textBackground/Objectives: Registered dietitian nutritionists (RDNs) are allied healthcare professionals who can help people with multiple sclerosis (MS) incorporate healthy eating, but little is known about their involvement in MS care. Thus, the objective of this survey was to investigate the perceptions and utilization of RDNs in MS care among multidisciplinary MS providers in the United States and Canada. Methods: An online survey was disseminated via the Consortium of MS Centers email listserv and MS-specific scientific conferences. The survey queried practitioner type, RDN referrals, the perceived benefits of RDNs in MS care, and the proportion of their patients who follow ‘MS diets’ or have nutrition-related issues. Reasons for or against RDN referral and beneficial resources were also queried. Results: Of the 60 completed surveys, respondents were primarily neurologists (n = 27, 45.0%). Most (n = 43, 71.7%) indicated that half or more of their patients inquire about diet, but n = 32 (53.3%) indicated that very few follow an ‘MS diet’ and n = 47 (78.3%) indicated that very few decline disease-modifying therapies to follow an ‘MS diet’. Most (n = 45, 77.6%) respondents indicated referring their patients to a RDN with lack of nutrition knowledge/general healthy eating advice (n = 34, 73.9%) and overweight/obesity (n = 31, 67.4%) as being the most common reasons for referral. RDNs were reported as being helpful or extremely helpful by n = 38 (84.4%) of respondents who reported referring to RDNs. Most (n = 46, 79.3%) indicated that their patients would benefit from having an RDN with MS-specialized training as a member of staff. Conclusions: MS care providers support the need for RDNs with specialized training in MS care.</p
Wearable Devices for Gait Retraining in Older Adults to Modify Performance in Locomotion
No full textAging reduces gait performance in older adults, decreasing their mobility and independence as well as increasing their mortality. For instance, they present shorter stride length, greater gait variability, increased instability, and greater cadence with reduced velocity. Such changes are observed in flat and inclined surfaces and could be reduced by physical activity. However, while walking is the most common and effective type of activity among older adults, some avoid it because they feel unsafe, unstable, or are unable to walk long distances.Previous studies have explored strategies to improve gait performance, including laboratory interventions with gait retraining programs. These interventions used equipment that continuously monitored movements. However, reproducing these conditions in outdoor environments and real-world scenarios is challenging and at times impractical.Wearable devices with biofeedback systems are emerging as an effective alternative solution that has proven to improve the gait in multiple populations. These devices use sensors on the body, such as force-sensitive resistors (FSR) and accelerometers, to collect gait data. These sensors are integrated with microcontrollers that interpret the data and provide immediate feedback to the user about how to modify gait, using multimodal sensory cues such as haptic biofeedback with vibrating buzzers.Wearable technologies improving gait in healthy older adults are limited. Current wearable devices designed to track gait mechanics in healthy older adults lack the ability to simultaneously provide personalized biofeedback. This thesis contains a series of studies investigating how wearable devices with biofeedback systems and smart wearable technology modified locomotion and improved gait performance in this population.A conceptual framework was initially developed to identify the biomechanics needs of healthy older adults during walking, as well as the available designs, technologies, applications, and protocols of wearable biofeedback devices used in healthy older adults, adults with musculoskeletal problems, and runners. Based on this conceptual framework two device prototypes were developed, and experimentally tested with GaitRite and Xsens MVN BIOMECH 3D motion capture systems, to assess the gait changes produced in healthy older adults in outdoor settings.The first device, a wireless smart insole system, measured the swing time using FSR sensors. We demonstrated that seven participants improved their gait after using this smart insole. The system provided biofeedback to encourage longer swing time during a 10-minute gait retraining session on a flat surface. The participants increased the stride length, hip flexion, and functional mobility while reducing the cadence without modifying the speed. These changes suggest positive increments in gait performance.Similar to many other biofeedback systems, the smart insole system provided feedback on one gait parameter only, attempting to modify a complex gait cycle. This led us to study whether a gait retraining session with the smart insole system could produce multiple response strategies in different individuals. After applying the same protocol to 13 healthy older adults with similar baseline gait characteristics, we demonstrated that a wearable biofeedback device that measured and fed back on swing time, produced two types of gait patterns, improving gait performance on a portion of the group only. The key difference between participants was that those who improved their gait presented a greater range of motion in the hip, especially during hip extension. They increased the stride length, reduced cadence, and maintained the same velocity. In contrast, the remaining participants walked slower, with increased knee flexion and increased gait variability in stance and step time. The results suggested that wearable devices in improving gait might need to be customized to individuals.The second device prototyped was an accelerometer-based device that monitored and fed back the landing acceleration at heel strike during downhill walking. In a pilot study, we reported some initial positive changes in the walk of a healthy older adult who used the device during a 15-minute gait retraining session. The stability improved by reducing the load and impulse at the rearfoot with an initial low increment in the displacement and velocity of the center of pressure but an important reduction of these variables later in the step.This thesis developed a framework regarding wearable biofeedback technology used in healthy older adults, adults with musculoskeletal disorders, and runners, which is essential to improve future prototype iterations. It contributes to the knowledge of strategies to improve gait in healthy older adults through gait retraining sessions with wearable biofeedback devices, inspiring future research that promotes walking. Additionally, this thesis explores practical technologies that offer immediate biofeedback and gait changes, allowing instant interventions in outdoor environments and informing future research protocols.</p
Fabrication of Ultrathin Metallic Sheets by Accumulative Pack Rolling
No full textUltrathin metal foils with thicknesses down to a few microns are used for a wide range of applications, including batteries, cable and component shielding and packaging. These foils are difficult to be produced using conventional rolling method because the minimum achievable thickness of conventional rolling is generally larger than the required thickness. More complex rolling techniques such as use of Sendzimir mills or use double rolling method. However, the Sendzimir mills are expensive to set up, the double rolling method still has a thickness limit. Severe plastic deformation (SPD) methods such as accumulative roll bonding (ARB) has also been investigated to produce ultrathin metal foils. The method could reduce the metal layers to ultrathin level but it often requires additional separation process to extract useful metal layers. It makes the process complex and limiting the manufacturability of some reactive metal materials.In our study, we proposed a novel accumulative pack rolling (APR) process, which has successfully been applied to fabricate ultrathin metal foils. By repetitively rolling sandwich sheet and replacing the pack sheet, extreme high reductions could be achieved. This work investigated the minimum achievable thickness, surface morphology, microstructure, texture, and defects that develops in the APR process.The APR method demonstrated remarkable capability in reducing the minimum achievable thickness of metal foils. For pure Al, Cu, Zn and Ni, the minimum achievable thickness could reach 1-3 μm. Study of the surface profiles showed that during the APR process, material surfaces underwent a noticeable roughness increase as a result of plastic deformation. This phenomenon was typically more pronounced in the early stages of deformation. The surfaces could exhibit peak-valley type patterns or particle like forms. The former could evolve to defects such as pinholes and cracks, leading to early failure and affecting the minimum achievable thickness. The peak-valley type of surface patterns could be supressed by replacing pack sheets after certain reduction, usually between 60% to 80%. Then the pinhole formation could be hindered and the thickness reduction could continue.To explain the surface roughening observed in the APR process, we drew insights from research on surface roughening during deformation of single layer metal sheets, as well as interface roughening or thickness irregularity in multilayer sheet deformation. It has been found that plastic instability is the primary reason for interface roughening or irregularity in the stacked metal sheets. At the macro scale, this is mainly attributed to differences in material flow properties between layers. At the micro scale, through Electron Backscatter Diffraction (EBSD) analysis of cross-sections of APR copper foils, we found that differences in grain flow properties resulting from variations in grain orientations can also lead to interface roughening. Numerical simulation techniques were also employed to validate this conclusion. We constructed polycrystalline models to simulate the deformation process of multilayer sheets and the results verified that differences in mechanical properties between grains or differences in the soft and hard orientations significantly influenced the surface roughening behaviour at the interface.Using the developed APR method and the theory of surface/interface roughening, we successfully produced AA1050/Ni and AA7075/Ni multilayered composite sheets with good layer continuity. Multilayered metal composites are usually fabricated by ARB. The method has some drawbacks such as the harder layer usually experiences necking and fracturing during the process so the layer continuity is poor. This could severely influence the application of materials such as Al/Ni composites as they discontinued layers could reduce the amount of heat released during exothermal reaction. Two strategies were adopted in our work: one is to use AA7075, whose mechanical properties are close to Ni, and the other is to use AA1050, but the AA1050 and Ni sheets were first reduced to thicknesses of 5-10 μm and then subjected to roll bonding to prepare AA1050/Ni multilayers. The Al/Ni multilayers maintained excellent layer continuity in both material combinations, with AA7075/Ni outperformed the AA1050/Ni sheets. The heat release of AA7075/Ni sheets in the differential scanning calorimetry (DSC) experiments also showed values close to the calculated theoretical values. This combined process of APR and roll bonding helps to control thickness irregularity during multilayer sheet deformation processes.</p