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1
Golinski, W. Z., i R. Gentle. "The influence of seat back rake on ligament loadings in rear-end impact". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 219, nr 2 (1.02.2005): 197–205. http://dx.doi.org/10.1243/095440705x6541.
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A biomechanical finite element (FE) model of the 50th percentile male human cervical spine, capable of predicting ligament loadings in whiplash scenarios, has been developed and previously reported. The study reported here analyses the influence of seat back rake on ligament injury in two scenarios: firstly, the in position, where the car occupant is looking forward and the head remains in the sagittal plane, and, secondly, the out of position, where the car occupant is initially looking slightly to one side. In both cases the results show an increase in ligament loading with a decrease of seat back rotational stiffness, substantiating the need for dynamic seat testing. Moreover, comparing individual ligament loading data shows that the initial head rotation scenario is more damaging to the cervical spine than the sagittal plane scenario, confirming a published hypothesis.
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Bagheri, Rasool, Ismail Ebrahimi Takamjani, Mohammad R. Pourahmadi, Elham Jannati, Sayyed H. Fazeli, Rozita Hedayati i Mahmood Akbari. "Trunk–Pelvis Kinematics Variability During Gait and Its Association With Trunk Muscle Endurance in Patients With Chronic Low Back Pain". Journal of Applied Biomechanics 36, nr 2 (1.04.2020): 76–84. http://dx.doi.org/10.1123/jab.2019-0322.
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The first purpose was to investigate the trunk muscle endurance, the second aim was to evaluate the trunk–pelvis kinematics during gait, and the third was to evaluate the relationship between trunk–pelvis kinematics and the trunk muscle endurance. Thirty participants (15 nonspecific chronic low back pain [NCLBP] and 15 healthy) were included. The authors first assessed trunk muscle endurance on endurance testing protocols. The authors next measured the trunk–pelvis kinematics during gait using a 3-dimensional motion capture system. Angular displacement, waveform pattern (CVp), and offset variability (CVo) were also examined. Statistical analysis revealed a significant difference in (1) the trunk muscle endurance and (2) sagittal, frontal, and transverse planes CVp between groups (P < .05). A significant moderate correlation was found between supine double straight-leg raise and frontal CVp (r = .521, P = .03) and transverse planes CVp (r = .442, P = .05). However, a significant moderate correlation was observed between prone double straight-leg raise and sagittal plane CVp (r = .528, P = .03) and transverse plane CVp (r = .678, P = .001). The relationship between (1) lower trunk extensor endurance with transverse and sagittal planes CVp and (2) lower abdominal muscle endurance with transverse and frontal planes CVp suggests that gait variability in these planes may result because of trunk muscle deconditioning accompanying NCLBP.
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Ferguson, Sue A., William S. Marras i Robert R. Crowell. "Three-Dimensional Functional Capacity of Normals and Low Back Pain Patients". Proceedings of the Human Factors and Ergonomics Society Annual Meeting 40, nr 14 (październik 1996): 737–41. http://dx.doi.org/10.1177/154193129604001404.
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Most current functional capacity evaluations focus on sagittal range of motion, strength testing as well as simulation of daily activities and job tasks as measures of wellness. The goal of this study was to evaluate the dynamic functional motion capacity of normals and low back pain patients in the three cardinal planes of the body. The hypothesis was that injury would not only affect sagittal motion but also lateral and twisting motions that would load the spine in a different manner. Trunk motion parameters of range of motion (ROM), velocity and acceleration were measured in all three planes of the body as subjects performed three separate experimental tasks, eliciting motion in each plane of the body. The MANOVA results showed a significant difference between the patients and normals. The final discriminant function model predicting membership for the two groups contained ROM, velocity, and acceleration parameters with two measures from each experimental task. The cross-validation error rate for the model was 4%. These results provide insight into new methods for functional capacity evaluation of low back pain patients which may influence return to work decisions.
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Fahr, Payam, Murat Yazici i Arun Shukla. "Shock response of filled corrugated sandwich structures under extreme temperatures". Journal of Sandwich Structures & Materials 20, nr 1 (2.06.2016): 130–49. http://dx.doi.org/10.1177/1099636216650987.
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Shock tube experiments were performed to investigate the blast response of corrugated steel cellular core sandwich panels filled with a silicone based syntactic foam at room and high temperatures. The syntactic foam filler was prepared by mixing a two-part silicone mixture with glass microspheres; its microstructure, and mechanical properties were also characterized. The syntactic foam-filled sandwich panels were loaded via air shock pressure by using the shock tube with a fixture capable of testing materials at temperatures up to 900℃. High-speed photo-optical methods, digital image correlation techniques, were used in tandem with optical band-pass filters and high intensity light sources for providing sufficient contrast at elevated temperatures. Back-face deformation images were captured using two synchronized high-speed cameras while a third camera captured the side view deformation images. The shock pressure profiles and digital image correlation analysis were used to obtain the impulse imparted to the specimen, transient deflection, in-plane strain and out-of-plane velocity of the back-face sheet. It was observed that using the syntactic foam as a filler material decreased the front face and back face deflections by 42% and 27%, respectively, as compared to the empty sandwich panel. At high temperatures, the silicone-based syntactic foam decomposes into silica, a stable and non-hazardous byproduct. The highest impulse was imparted to the specimen at room temperature and subsequently lower impulses with increasing temperatures were observed. Due to the increased ductility of steel at high temperatures, the specimens demonstrated an increase in back face deflection, in-plane strain and out-of-plane velocity with increased temperatures, with weld failure being the primary form of core damage.
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Chen, Wen Chin, Pen Hsi Liou i Bo Jui Chen. "Optimization Design for the Longitudinal Structure of LED Light Guide Plate Using Soft Computing". Advanced Materials Research 690-693 (maj 2013): 2994–3000. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.2994.
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The study proposes an optical optimal design system of light guide plate (LGP). The optimization design is conducted in the longitudinal structure of the LGP incidence plane with 3-piece LED light source. Taguchi method is also used in carrying out the design of experiment through the TracePro, optical analysis software, and the experiment data were employedd as the back-propagation neural network (BPNN) training and testing samples, and then created an optical quality predictor of the longitudinal structure; BPNN can predict the impact of incidence plane luminance versus the different constructed parameters. Finally, the optical quality predictor can effectively generate the optimal parameters settings combined with genetic algorithm (GA). The simulation results show that the proposed system improves the non-uniformity problem of the incidence plane but also makes it easier to design the longitudinal structure of the incidence plane.
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Sugeta, Atsushi, i Yoshihiko Uematsu. "In-Situ Atomic Force Microscopy and Crystallo Graphic Orientation Analysis of Small Fatigue Crack Deflection Behavior". Key Engineering Materials 345-346 (sierpień 2007): 227–30. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.227.
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Successive observation of transgranular small fatigue crack growth behavior of alpha-brass was performed by means of an atomic force microscope (AFM) equipped with small in-plane bending fatigue testing machine. The fatigue crack deflection behavior, which was observed frequently in the low growth rate region, was investigated by the crystallographic orientation analysis based on the Electron Back Scatter Diffraction (EBSD) technique. The slip factor considering the slip system and singular stress field at the crack tip was introduced in order to evaluate the easiness of slip deformation instead of Schmid factor. The direction of crack deflection was found to be explained well by the slip factor and the geometric relative location between the preferential slip plane and crack front.
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Giongo, Ivan, Dmytro Dizhur, Roberto Tomasi i Jason M. Ingham. "In-Plane Assessment of Existing Timber Diaphragms in URM Buildings via Quasi-Static and Dynamic In Situ Tests". Advanced Materials Research 778 (wrzesień 2013): 495–502. http://dx.doi.org/10.4028/www.scientific.net/amr.778.495.
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Mechanical and dynamic in-plane properties of timber diaphragms are known to be key parameters when determining both the local and global seismic response of unreinforced masonry (URM) buildings. However, few data pertaining to experimental campaigns on this issue are available in the literature, especially regarding existing floors. In this work, the outcomes of a field testing campaign on full-scale old timber diaphragms are presented. Two specimens, whose size was 5.6 x 9.6 m2 and 4.7 x 9.6 m2 were obtained from a 17 x 9.6 m2 floor and were subjected to a series of both cyclic and snap back tests in the direction orthogonal to the joists. Since the original anchoring system was deficient, new epoxy-grouted anchors were installed before starting the testing procedure. So as to reproduce the inertial load distribution, an ad hoc loading system was developed by means of wire ropes and steel pulleys. After testing the diaphragms in the as-built condition, the effect of different refurbishment techniques was also investigated. From the results, it seems that even simple and cost-effective solutions such as the re-nailing of the flooring are sufficient to achieve a significant increase in the equivalent shear stiffness.
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Korakakis, Vasileios, Kieran O’Sullivan, Argyro Kotsifaki, Yiannis Sotiralis i Giannis Giakas. "Lumbo-pelvic proprioception in sitting is impaired in subgroups of low back pain–But the clinical utility of the differences is unclear. A systematic review and meta-analysis". PLOS ONE 16, nr 4 (26.04.2021): e0250673. http://dx.doi.org/10.1371/journal.pone.0250673.
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Background Altered spinal postures and altered motor control observed among people with non-specific low back pain have been associated with abnormal processing of sensory inputs. Evidence indicates that patients with non-specific low back pain have impaired lumbo-pelvic proprioceptive acuity compared to asymptomatic individuals. Objective To systematically review seated lumbo-pelvic proprioception among people with non-specific low back pain. Methods Five electronic databases were searched to identify studies comparing lumbo-pelvic proprioception using active repositioning accuracy in sitting posture in individuals with and without non-specific low back pain. Study quality was assessed by using a modified Downs and Black’s checklist. Risk of bias was assessed using an adapted tool for cross-sectional design and case–control studies. We performed meta-analysis using a random effects model. Meta-analyses included subgroup analyses according to disability level, directional subgrouping pattern, and availability of vision during testing. We rated the quality of evidence using the GRADE approach. Results 16 studies met the eligibility criteria. Pooled meta-analyses were possible for absolute error, variable error, and constant error, measured in sagittal and transverse planes. There is very low and low certainty evidence of greater absolute and variable repositioning error in seated tasks among non-specific low back pain patients overall compared to asymptomatic individuals (sagittal plane). Subgroup analyses indicate moderate certainty evidence of greater absolute and variable error in seated tasks among directional subgroups of adults with non-specific low back pain, along with weaker evidence (low-very low certainty) of greater constant error. Discussion Lumbo-pelvic proprioception is impaired among people with non-specific low back pain. However, the low certainty of evidence, the small magnitude of error observed and the calculated “noise” of proprioception measures, suggest that any observed differences in lumbo-pelvic proprioception may be of limited clinical utility. PROSPERO-ID CRD42018107671
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Sugeta, Atsushi, Yoshihiko Uematsu i M. Jono. "A Study on the Mechanism of Small Fatigue Crack Deflection Behavior in Alpha-Brass by Means of In Situ Atomic Force Microscopy and Crystallo-Graphic Orientation Analysis". Key Engineering Materials 353-358 (wrzesień 2007): 1225–28. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.1225.
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Successive observation of transgranular small fatigue crack growth behavior of alpha-brass was performed by means of an atomic force microscope (AFM) equipped with small in-plane bending fatigue testing machine. In the low growth rate region after crack initiation, the fatigue crack grew in a zig-zag manner as a result of successive crack branching and deflection. The fatigue crack deflection behavior was investigated by the crystallographic orientation analysis based on the Electron Back Scatter Diffraction (EBSD) technique. The slip factor considering the slip system and singular stress field at the crack tip was introduced in order to evaluate the easiness of slip deformation instead of Schmid factor. The direction of crack deflection was found to be explained well by the slip factor and the geometric relative location between the preferential slip plane and crack front.
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Fu, Jian, Jun Wei Zhang i Ren Bo Tan. "A Straight-Line Trajectory Tomography Method Based on Multiple Tilted X-Ray Cone-Beams". Applied Mechanics and Materials 239-240 (grudzień 2012): 238–42. http://dx.doi.org/10.4028/www.scientific.net/amm.239-240.238.
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A straight-line trajectory tomography method, based on multiple tilted X-ray cone-beams formed by multiple sources and detectors, is investigated. In this method, multiple cone-beams are fixed and tilted at different positions and only the object translates along a straight-line trajectory. This kind of imaging method may have potential applications in industry testing and security inspections. As is known, projection data from a straight-line trajectory based on single cone-beam are incomplete and their reconstruction suffers from a limited-angle problem. The proposed straight-line trajectory tomography method based on multiple tilted X-ray cone-beams can be used to compensate these deficiencies. To reconstruct images, the filtered back-projection (FBP) reconstruction algorithm for the middle plane is first derived from the Fourier slice theorem. It is then extended to non-middle planes with the Feldkamp-Davis-Kress (FDK) approximation. Numerical simulations validate our method.
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Callaghan, Jack P., Samuel J. Howarth i Tyson A. C. Beach. "Validation of occupational estimates of cumulative low-back load". Occupational Ergonomics 10, nr 3 (5.07.2012): 113–24. http://dx.doi.org/10.3233/oer-2012-0196.
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In most genuine industrial settings, it is not yet feasible to directly measure in vivo tissue loads, nor is it practical to estimate dynamic load-time histories using biomechanical models. Thus, data extrapolation techniques are often used for obtaining occupational estimates of shift or daily cumulative low-back load exposures. These techniques are reliant on the assumption that the observed duty cycle of apparently stereotypical work is consistent over long working durations. This investigation evaluated the validity of this assumption using a controlled laboratory-based repetitive lifting task. Nine men performed 30-minutes of sagittal plane repetitive lifting tasks. Upper body kinematics were captured during the tasks, and a two-dimensional dynamic biomechanical model was used to generate peak and cumulative estimates of low-back loads. Over the course of the 30-minute testing sessions, kinematic adaptations at the elbow were responsible for an 8% reduction in duty cycle duration while peak low-back load magnitudes remained consistent. Combining reductions in duty cycle duration with negligible changes in peak loading contributed to a small decrease (⩽ 10%) in cumulative low-back load over the final 20-minutes of lifting. However, when data extrapolation was incorporated to estimate a shift exposure it was found that these changes could overestimate occupational cumulative low-back loading exposures by 10–27% inferences made regarding the risk of low-back pain or injury reporting associated with exposure.
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Chen, Wen-Chin, Pen-Hsi Liou i Bo-Jui Chen. "An Optimization System Applied in Optical Design of LED Light Guide Plate". Open Mechanical Engineering Journal 7, nr 1 (29.11.2013): 108–15. http://dx.doi.org/10.2174/1874155x01307010108.
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Most of the small and medium-sized backlight modules are applied to a small amount of various products. Since the time to design a product is rigid and the light guide plate (LGP) is the key component that affects the quality of backlight modules, photovoltaic industries can enhance the core competence if they are able to develop high standard light guide plates with fast and efficient methods. The study proposes an optical optimal design system of light guide plate (LGP). The optimization design is conducted in the longitudinal structure of the LGP incidence plane with three LED light sources. Taguchi method is also used in carrying out the design of experiment through the TracePro, optical analysis software, and the experiment data which are employed as the back-propagation neural network (BPNN) training and testing samples and, then, created an optical quality predictor of the longitudinal structure. BPNN can predict the impact of incidence plane luminance versus the different constructed parameters. Finally, the optical quality predictor can effectively generate the optimal parameters settings combined with genetic algorithm (GA). The simulation results show that the proposed system can improve the non-uniformity problem of the incidence plane but also make it easier to design the longitudinal structure of the incidence plane.
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Xin, Ke, Wei Zuo i Jing Feng Zhi. "Automatic Testing Equipment and Experiments Based on the Quantitative Shadow Method for Measuring Sub-Nanometer Deformations on Aspheric Surface". Key Engineering Materials 375-376 (marzec 2008): 608–13. http://dx.doi.org/10.4028/www.scientific.net/kem.375-376.608.
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A novel quantitative shadow testing equipment is presented based on the digital imageprocessing technique for characterizing local surface deformations on optical surface. Two magnetic stepping motors control the positions of the knife-edge for cutting the wave-front reflected back from the aspheric surface separately. At each position of the knife-edge blocking the image on the focal plane, it is recorded and analyzed by an image-processing set-up behind the knife-edge under computer control. Based on a group of images recorded, the analysis of local slopes is performed by picking up characteristics of illumination levels. Further the relationship between the changes of illumination level and deformations on surface is built on the principle of Fourier Optics. The results of tests approve that the method is effective on determining the characteristics of two parabolic surfaces using magnetorheological finishing.
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Niimi, Ryosuke, i Kazuhiko Yokosawa. "Viewpoint Dependence in the Recognition of Non-Elongated Familiar Objects: Testing the Effects of Symmetry, Front-Back Axis, and Familiarity". Perception 38, nr 4 (1.01.2009): 533–51. http://dx.doi.org/10.1068/p6161.
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Visual recognition of three-dimensional (3-D) objects is relatively impaired for some particular views, called accidental views. For most familiar objects, the front and top views are considered to be accidental views. Previous studies have shown that foreshortening of the axes of elongation of objects in these views impairs recognition, but the influence of other possible factors is largely unknown. Using familiar objects without a salient axis of elongation, we found that a foreshortened symmetry plane of the object and low familiarity of the viewpoint accounted for the relatively worse recognition for front views and top views, independently of the effect of a foreshortened axis of elongation. We found no evidence that foreshortened front–back axes impaired recognition in front views. These results suggest that the viewpoint dependence of familiar object recognition is not a unitary phenomenon. The possible role of symmetry (either 2-D or 3-D) in familiar object recognition is also discussed.
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Kumar, V. Ram, i M. L. Munjal. "Plane wave frequency domain analysis of resonance free pipes with moving medium". Noise Control Engineering Journal 67, nr 6 (1.11.2019): 467–82. http://dx.doi.org/10.3397/1/376743.
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Mufflers are inevitably a significant part of the exhaust systems of automobiles for bringing down the tail-pipe noise levels. Nevertheless, howsoever well-optimized a reasonably large muffler volume be (with respect to insertion loss, back pressure, breakout noise, flow noise, etc.), there are inevitably acoustic modes present, which lead to peaks in the noise levels and corresponding troughs in the insertion loss (IL) of an exhaust baseline. These acoustic modes are: (i) muffler internal modes, (ii) axial pipe modes and (iii) system modes. Of these, the axial pipe mode is the most detrimental one. Usage of microperforated (MPA) patches along long pipes at locations of sound pressure anti-nodality to dampen their resonances has proved to be an efficient acoustic solution. All the works reported so far on these resonance free pipes with such patches have been using 3D FEM or vehicle testing. This article discusses their acoustic performance employing linear plane wave theory. The predicted acoustic behavior comes in-line with those of published resources. Also, the flow leakage through the open patches and the corresponding attenuation impact have been demonstrated. It has been shown that the seemingly inconsequential leakage deteriorates the patch acoustics considerably. This result is verified with the published claims, thereby further validating the 1D analysis presented here. Also, the 1D approach has a scope for valuable benchmarking of resonance free pipes (RFPâ,,¢) in industry since it does not suffer any intrinsic modeling deficiency unlike some commercial simulation solvers. The article, thus, presents, validates and illustrates the potential of linear acoustic analysis toward the acoustic assessment and optimization of RFPs.
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Jeon, Gwang-Hun, Philip Ayiku Dzagbletey i Jae-Young Chung. "A Cross-Joint Vivaldi Antenna Pair for Dual-Pol and Broadband Testing Capabilities". Journal of Electromagnetic Engineering and Science 21, nr 3 (31.07.2021): 201–9. http://dx.doi.org/10.26866/jees.2021.3.r.27.
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The non-standalone 5G antenna wireless communication standard and devices operating under Wi-Fi 5, 6, and 6E operate at the 3 GHz frequency bands and above. With the increasing demand for these devices and technologies, it is crucial to test them rapidly and economically for commercial usage. This paper presents a dual-polarized Vivaldi antenna for the over-the-air (OTA) measurement of wireless communication devices used in the 3–7 GHz band. The dual-polarization performance is realized by vertically intersecting two planar Vivaldi antennas and soldering them at the back end. A three-step 1/4 wavelength balun is applied to the input for the wideband impedance matching of the antenna, which is attached to a Teflon holder for easy mounting. It has excellent performance and is designed to be manufactured at low cost. The fabricated antenna was tested in an anechoic chamber and showed S11 less than -10 dB from 2.63–7.15 GH, and a realized gain of more than 5 dBi from 3 GHz and above. A measured half-power beam width of more than 60° was realized with symmetric E/H-plane. Much of the required symmetry was achieved with the designed Teflon holder. The antenna has a measured cross-polarization discrimination of better than 15 dB across the entire operating bandwidth.
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Rawlings, G. E. "Active slide in Tertiary bentonitic claystones, Upper Hat Creek, British Columbia". Canadian Geotechnical Journal 23, nr 2 (1.05.1986): 164–73. http://dx.doi.org/10.1139/t86-026.
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Potential exploitation of the 500 m thick coal deposit at Upper Hat Creek, British Columbia, required detailed investigation of the sequence of Tertiary tuffaceous rocks surrounding the coal and the overlying surficial materials. Studies have shown that extensive bentonitic slide deposits partially cover the coal body on the west side of Hat Creek valley; part of this area is currently active. A translational debris slide of approximately 17 × 106 m3 volume and 2 km length is moving across the northwest boundary of the proposed pit into the valley bottom.Detailed field investigations complemented by laboratory testing have defined the basal plane of sliding and permitted a back-analysis to be made. From measured piezometric pressures, the mobilized shear strength on the failure plane is calculated to be [Formula: see text], cr′ = 0, which is largely in accord with laboratory test results.Slope stability in thick montmorillonite-rich claystones/siltstones is known to present difficulties, as evidenced by the Panama Canal excavations. Consideration is given to the engineering significance of bentonitic slides and preventive measures that might be adopted in their control. Key words: active slide, Tertiary, claystone, montmorillonite, open pit, coal, monitoring, residual strength, piezometric pressures.
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Kelly, M. A., N. Morelli, H. L. Clayton, A. M. Parks, N. R. Heebner i M. C. Hoch. "A-25 The Effect of Cognitive Dual-Tasks on Dynamic Postural Sway During Sub-Maximal Gait on a Treadmill". Archives of Clinical Neuropsychology 35, nr 5 (18.06.2020): 621. http://dx.doi.org/10.1093/arclin/acaa036.25.
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Abstract Objective To investigate the effect of a cognitive task on postural control during treadmill walking. We hypothesized that postural sway acceleration would decrease during dual-task compared to single-task gait. Method Ten (5 females, 5 males) physically active, healthy young adults (Age: 22.50 ± 3.01) with no history of cognitive deficits or head injury were recruited from a University campus for this cross-sectional study. Participants reported to a biomechanics laboratory for a single testing session and completed two, 5-minute walking trials on a treadmill at 90% of maximal gait-speed under single and dual-task conditions while instrumented with a single inertial measurement unit (IMU) on the lower-back. During dual-task gait, participants concurrently performed a Stroop Test displayed on a mounted screen in front of the treadmill during the entire trial. Root mean square (RMS) of acceleration was analyzed in the medial-lateral, anterior-posterior, superior-inferior, and resultant planes during the dual-task trial. Paired t-tests and effect sizes (ES) were calculated for each sway plane between single and dual-tasks. Results No differences were identified between single and dual-task RMS acceleration in the medial-lateral (p = 0.98, ES = 0.01), anterior-posterior (p = 0.49, ES = 0.23) or superior-inferior (p = 0.98, ES = 0.01) planes. However, the RMS acceleration in the resultant plane was lower in the dual-task condition (Mean Difference: 0.031 ± 0.037; p = 0.02, ES = 0.85). Conclusions This novel dual-task gait paradigm utilized constant sub-maximal gait speed to investigate the influence of a sustained cognitive dual-task on postural sway using a single IMU. These preliminary results indicate that this dual-task gait paradigm may affect gross postural sway in healthy adults.
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Gill, John D., Vincent R. Capece i Ronald B. Fost. "Experimental Methods Applied in a Study of Stall Flutter in an Axial Flow Fan". Shock and Vibration 11, nr 5-6 (2004): 597–613. http://dx.doi.org/10.1155/2004/596706.
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Flutter testing is an integral part of aircraft gas turbine engine development. In typical flutter testing blade mounted sensors in the form of strain gages and casing mounted sensors in the form of light probes (NSMS) are used. Casing mounted sensors have the advantage of being non-intrusive and can detect the vibratory response of each rotating blade. Other types of casing mounted sensors can also be used to detect flutter of rotating blades. In this investigation casing mounted high frequency response pressure transducers are used to characterize the part-speed stall flutter response of a single stage unshrouded axial-flow fan. These dynamic pressure transducers are evenly spaced around the circumference at a constant axial location upstream of the fan blade leading edge plane. The pre-recorded experimental data at 70% corrected speed is analyzed for the case where the fan is back-pressured into the stall flutter zone. The experimental data is analyzed using two probe and multi-probe techniques. The analysis techniques for each method are presented. Results from these two analysis methods indicate that flutter occurred at a frequency of 411 Hz with a dominant nodal diameter of 2. The multi-probe analysis technique is a valuable method that can be used to investigate the initiation of flutter in turbomachines.
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Guihard, Vincent, Frédéric Taillade, Jean-Paul Balayssac, Barthélémy Steck i Julien Sanahuja. "Permittivity measurement of cementitious materials and constituents with an open-ended coaxial probe: combination of experimental data, numerical modelling and a capacitive model". RILEM Technical Letters 4 (10.07.2019): 39–48. http://dx.doi.org/10.21809/rilemtechlett.2019.77.
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The study presents the development of a new two-dimensional FEM numerical model describing the operation of two large open-ended coaxial probes designed to investigate the permittivity of concrete, and its constituents. This numerical simulation, combined with a capacitive approach describing the behaviour of the probes, enabled to prove the suitability of such device to determine the permittivity of dispersive dielectrics. Finding back the permittivity of a specified material by calculation of the S parameters, change of the reference plane and use of the capacitive model is the key to the proof. Measurements performed onto different materials show good similarities with the numerical simulations. Special considerations are mentioned concerning the size of the probe and its ability to measure the permittivity of heterogeneous materials made of large inclusions. Combination of such numerical tool and measuring device can be used as a non-destructive testing technique to assess the near surface permittivity of concrete structures or as a calibration technique for GPR measurements.
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Karim, M. R., G. Manivannan, C. T. Gnanendran i S.-C. R. Lo. "Predicting the long-term performance of a geogrid-reinforced embankment on soft soil using two-dimensional finite element analysis". Canadian Geotechnical Journal 48, nr 5 (maj 2011): 741–53. http://dx.doi.org/10.1139/t10-104.
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The consolidation of the soft foundation soil of a geogrid-reinforced embankment, improved with prefabricated vertical drains (PVDs), is modelled in this paper using two-dimensional (2D) plane strain coupled finite element (FE) analysis to predict long-term multiple behaviour characteristics (e.g., settlement, lateral displacement, excess pore-water pressure response, geosynthetic strain) of the embankment. Two sets of analyses were carried out with the foundation soil being modelled using relatively simple elastic–viscoplastic (EVP) models. A nonlinear creep function was used in association with them. The input material parameters were determined from extensive laboratory testing or were taken from reliable sources except for the horizontal permeability, which was systematically back-estimated using oedometer test data and the first year of field settlement data. The results from both analyses were compared with the long-term (up to 6 years) field-monitoring data and were found to be in good agreement with the field measurements.
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Al Zoubi, Fadi M., i Richard A. Preuss. "Reliability of a Measure of Total Lumbar Spine Range of Motion in Individuals with Low Back Pain". Journal of Applied Biomechanics 29, nr 6 (grudzień 2013): 670–77. http://dx.doi.org/10.1123/jab.29.6.670.
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Measuring lumbar spine range of motion (ROM) using multiple movements is impractical for clinical research, because finding statistically significant effects requires a large proportion of subjects to present with the same impairment. The purpose of this study was to develop a single measure representing the total available lumbar ROM. Twenty participants with low back pain performed three series of eight lumbar spine movements, in each of two sessions. For each series, an ellipse and a cubic spline were fit to the end-range positions, measured based on the position of the twelfth thoracic vertebra in the transverse plane of the sacrum. The area of each shape provides a measure of the total available ROM, whereas their center reflects the movements’ symmetry. Using generalizability theory, the index of dependability for the area and anterior-posterior center position was found to be 0.90, but was slightly lower for the mediolateral center position. Slightly better values were achieved using the spline-fitting approach. Further analysis also indicated that excellent reliability, and acceptable minimal detectable change values, would be achieved with a single testing session. These data indicate that the proposed measure provides a reliable and easily interpretable measure of total lumbar spine ROM.
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Simon, Jorge, Hugo Perez-Guerrero, Jorge Sosa-Pedroza, Fabiola Martínez-Zúñiga, Juvenal Villanueva-Maldonado, Jorge Flores-Troncoso i Marco Cardenas-Juarez. "Design of an Ultrawideband Circularly Polarized Printed Crossed-Dipole Antenna Based on Genetic Algorithms for S-Band CubeSat Applications". International Journal of Antennas and Propagation 2021 (10.09.2021): 1–13. http://dx.doi.org/10.1155/2021/8733427.
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As in any satellite, onboard antennas for CubeSats are crucial to establish communication with ground stations or other satellites. According to its application, antennas must comply with standardized requirements related to size, bandwidth, operating frequency, polarization, and gain. This paper presents an ultrawideband circularly polarized two-layer crossed-dipole microstrip antenna for S-band CubeSat applications using genetic algorithms optimization tools included in the 3D electromagnetic simulation software Ansys HFSS. The antenna is constructed on a 10 × 10 cm Cuclad-250 substrate with a back copper flat plane, located at λ/4 at 2.25 GHz operating frequency. The backplane with the exact substrate dimensions improves gain and reduces inside satellite radiation. Measured bandwidth defined by S11 at a −10 dB was higher than 1835 MHz with S11 = −24.68 dB at the central frequency of 2.25 GHz, while measured VSWR at the same frequency was 1.124. At 2.25 GHz, the maximum measured gain and the minimum measured axial ratio in the broadside direction were found to be 6 dBi and 0.22 dB, respectively. There are antenna simulations and measurements, as long as its fabrication guarantees application requirements that make it ready for prespace testing.
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Recatala, Maria Arce, Soledad Garcia Morales i Nathan van den Bossche. "Experimental assessment of rainwater management of a ventilated façade". Journal of Building Physics 42, nr 1 (20.07.2017): 38–67. http://dx.doi.org/10.1177/1744259117719077.
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Façades are not watertight systems in which the exterior surface of the cladding plays the role of the water shedding surface; the air space is the drainage plane; the exterior surface of the thermal insulation layer acts as water-resistive barrier, and the interior layer of the inner leaf is supposed to be the air barrier. The degree of watertightness of ventilated façades relies on the characteristics of the materials used, the geometry of the external cladding element, and edge profile of the joints. Hence, in this article, we extrapolate the laboratory testing to develop a holistic approach on the water management of ventilated façades. The laboratory test showed that 50% of the water deposited to the surface of the wall splashes back, 22% creates a runoff film along the exterior surface of the cladding, 27% infiltrates into the cavity behind the cladding, and <1% reaches the inner layer of the wall. Given these results, the moisture load has been determined for a range of wind-driven rain loads and vertical joint configurations. Such information can be used as input to hygrothermal simulations.
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., Sutrisno, Firdaus RS, Zainuri A, Sigit Iswahyudi i Setyawan Bekti Wibowo. "Performance Analysis and Visualization of Canard and Fuselage Effects on Flow Patterns around a Straight-Body-Type-Fuselage (SBTF) Fighter Models with Experimental Method in Water Tunnel". Modern Applied Science 12, nr 10 (29.09.2018): 195. http://dx.doi.org/10.5539/mas.v12n10p195.
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Performance analysis and visualization of canard and fuselage effects on flow patterns around an SBTF fighter model have been conducted. An SBTF fighter model with an experimental method in a water tunnel would easily reveal visually the vortex dynamics phenomenon that occurred. Testing has been done, with some form of non-canard and canard aircraft in a water tunnel, on vortex dynamics and aerodynamic power on the aircraft model. The stream demonstration used a fluid speed of 0.1 m/s and Reynolds number 6.577x103 on a 1:110 scale model and measured using dye injection method with a print ink type with a mixture ratio of 1:8. The result of the research using GAMA water tunnel showed the aerodynamic force and vortex dynamics phenomenon that happened on the model aircraft. The research on the benefits of the canard is also done by examining the performance and the flow visualization of an SBTF fighter without fuselage, with the symmetrical plane and with the regular fuselage in a water tunnel. The results showed that the use of canard affected the lift, drag, and flow pattern around the wings. The use of canard can enhance the lift of the plane and function to delay the stall by restoring the flow above the wing which should have experienced turbulence back into laminar so that the fighter can maneuver to a higher angle of attack (AoA) without stalling. It is identified that canard and fuselage play significant roles on the design of a fighter. The design choice of the fuselage and the employment of canard are fundamental to support the ability of maneuver and agility of the fighter.
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Hua, Ming Guo, Zhen Jiang Yu i Bo Wei Lei. "Research and Application of Mobile Gas-Extraction Technology on the Upper Corner of Working Face". Advanced Materials Research 726-731 (sierpień 2013): 789–97. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.789.
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Aiming at solving the existing problems of gas treatments on the upper corner presently,poor drainage effect and the high cost of engineering quantity included , gas drag pipe drainage technology and processes on the upper corner is designed.It can make the drainage point matching working face advance speed, realize continuous drainage points in space.And research on the drainage parameters is the foundation of the successful implementation of drag drainage pipe technology.It introduced Brinkman equation, Fick's law of diffusion and gas diffusion translational equations to describe the behavior of gas flow diffusion ,established the migration and diffusion gas flow model at working face ,and the two models are combined in a unified flow field., establishing a coupling model of multi-physics gas flow at the working face.And the model is solved by fluent to determine the optimal parameters of towing pipe drainage.Finally,it makes a practical application and testing results in Changcun coal mine working face N3-8. The results show that gas drag pipe drainage technology is conducing to governing on the accumulation of corner gas,and the gas concentration on the upper corner down to 1%,determining the best the drainage location for distance back plane 2.4m, an inclined direction distance back to the wind tunnel 1.6m, along strike depth to goaf 15m .Taking measures to block the upper corner,which can improve the drainage concentration,and make the concentration of gas on the upper corner down to 0.6%.The application of field basically agrees with the simulation results,so pipe drainage technology has feasibility and good applicability of top corner gas drag
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Wang, Jing, Naike Du, Tiantian Yin, Rencheng Song, Kuiwen Xu, Sheng Sun i Xiuzhu Ye. "A Machine Learning-Assisted Inversion Method for Solving Biomedical Imaging Based on Semi-Experimental Data". Electronics 12, nr 12 (10.06.2023): 2623. http://dx.doi.org/10.3390/electronics12122623.
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Machine learning approaches have been extensively utilized in the field of inverse scattering problems. Typically, the training dataset is generated synthetically using ideal radiation sources such as plane waves or cylindrical waves. However, the testing data often consist of experimental data that take into account the antenna port couplings and waveform distortions within the system. While noise can be artificially added to synthetic data, it may not accurately represent the real experimental noise. Consequently, the application of machine learning-assisted inversion techniques may encounter challenges when the training dataset differs significantly from the experimental data. In this paper, we propose an experimental system specifically designed for human body imaging. A semi-experimental training dataset is constructed using full-wave simulation software, incorporating the relative permittivities of common human tissues. Furthermore, the system noise is meticulously considered through full-wave simulation, enhancing the authenticity of the dataset. A back-propagation scheme is firstly employed to obtain the rough reconstructed images. Then, the U-net convolutional neural network (CNN) is employed to map these rough images to high-resolution ones. Numerical results demonstrate that, in comparison to networks trained solely on synthetic data, the network trained using semi-experimental data achieves superior reconstruction results with lower errors and improved image quality.
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Baus, Juan, John R. Harry i James Yang. "Optimization-based subject-specific planar human vertical jumping prediction: Model development and validation". Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 235, nr 7 (16.04.2021): 805–18. http://dx.doi.org/10.1177/09544119211010924.
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Jumping biomechanics may differ between individuals participating in various sports. Jumping motion can be divided into different phases for research purposes when seeking to understand performance, injury risk, or both. Experimental-based methods are used to study different jumping situations for their capabilities of testing other conditions intended to improve performance or further prevent injuries. External loading training is commonly used to simulate jumping performance improvement. This paper presents the optimization-based subject-specific planar human vertical jumping to develop the prediction model with and without a weighted vest and validate it through experiments. The skeletal model replicates the human motion for jumping (weighting, unweighting, breaking, propulsion) in the sagittal plane considering four different loading conditions (0% and 10% body mass): unloaded, split-loaded, front-loaded, and back-loaded. The multi-objective optimization problem is solved using MATLAB® with 35 design variables and 197 nonlinear constraints. Results show that the model is computationally efficient, and the predicted jumping motion matches the experimental data trend. The simulation model can predict vertical jumping motion and can test the effect of different loading conditions with weighted vests and arm-swing strategy on the ground reaction forces. This work is novel in the sense that it can predict ground reaction forces, joints angles, and center of mass position without any experimental data.
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Wang, Shuangbu, Nan Xiang, Yu Xia, Lihua You i Jianjun Zhang. "Real-time surface manipulation with $$C^{1}$$ continuity through simple and efficient physics-based deformations". Visual Computer 37, nr 9-11 (17.06.2021): 2741–53. http://dx.doi.org/10.1007/s00371-021-02169-4.
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AbstractWe present a novel but simple physics-based method to interactively manipulate surface shapes of 3D models with $$ C^1 $$ C 1 continuity in real time. A fourth-order partial differential equation involving a sculpting force originating from elastic bending of thin plates is proposed to define physics-based deformations and achieve $$ C^1 $$ C 1 continuity at the boundary of deformation regions. In order to obtain real-time physics-based surface manipulation, we construct a mapping relationship between a deformation region in a 3D coordinate space and a unit circle on a 2D parametric plane, formulate corresponding $$ C^1 $$ C 1 continuous boundary conditions for the unit circle, and obtain a simple analytical solution to describe the physics-based deformation in the unit circle caused by a sculpting force. After that, the obtained physics-based deformation is mapped back to the 3D coordinate space, and added to the original surface to create a new surface shape with $$ C^1 $$ C 1 continuity at the boundary of the deformation region. We also develop an interactive user interface as a plug-in of the 3D modelling software package Maya to achieve real-time surface manipulation. The effectiveness, easiness, real-time performance, and better realism of our proposed method is demonstrated by testing surface deformations on several 3D models and comparing with other methods and ground-truth deformations.
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Omumbo, Nicholas J., Titus M. Muhambe i Cyprian M. Ratemo. "Evaluation of Routing Performance using OSPF and Multi-Controller Based Network Architecture". International Journal of Computer Network and Information Security 13, nr 4 (8.08.2021): 45–61. http://dx.doi.org/10.5815/ijcnis.2021.04.05.
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Newer mobile applications are increasingly being defined using Internet Protocol, resulting in increased use of Internet Protocol and subsequent upsurge of smartphones. However, many communication service provider core networks continue to use classical routing protocols and single controller-based networks if deployed. Controller-based networks built on the foundation of software-defined networks include centralization and separation of control plane and data plane, which can address the challenges experienced with the classical routing protocols. When single controllers are used, they tend to get overloaded with traffic. The ability to use multi-controller-based network architecture to improve quality of service in the mobile IP core network is still an open issue. This paper presents a performance evaluation of multi-controller-based network architecture, running OpenFlow and Open Shortest Path First protocol. The long-term evolution simulated network architecture is created using well-known network simulator Objective Modular Network Testbed running OpenFlow and simuLTE add-on. We test and analyze data traffic for Packet data ratio and Jitter and their associated effects on a multi-controller-based network running OpenFlow versus OSPF on a mobile core network. The experiment created two topologies; multi controller-based and Open Shortest path first network. Video and ping traffic is tested by the generation of traffic from User Equipment to the network-based server in the data center and back, and traffic metrics recorded on an inbuilt integrated development environment. The simulation setup consisted of an OpenFlow controller, HyperFlow algorithm, OpenFlow switches, and Open Shortest Path First routers. The multi-controller-based network improved Jitter by 10 ms. The Open Shortest Path first showed packet data ratio values of 89% gain while the controller-based network registered a value of 86%. A standard deviation test revealed 0.7%, which shows that the difference is not significant when testing for Packet data ratio. We provided insight into the performance of multi-controller-based architecture and Open Shortest Path First protocol in the communication service provider's core network.
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Ma, Xinhui, Catherine Martin, Grant McIntyre, Ping Lin i Peter Mossey. "Digital Three-Dimensional Automation of the Modified Huddart and Bodenham Scoring System for Patients with Cleft Lip and Palate". Cleft Palate-Craniofacial Journal 54, nr 4 (lipiec 2017): 481–86. http://dx.doi.org/10.1597/15-340.
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Objective The modified Huddart and Bodenham scoring system assesses maxillary arch constriction and surgical outcomes in cleft lip and palate. This project automates modified Huddart and Bodenham scoring using three-dimensional digital models. Design Development of a novel software tool. Setting The design, construction, development, and testing of the system was carried out at Dundee Dental Hospital. Patients, Participants Subjects with cleft lip and palate. Interventions A plug-in has been developed using an open three-dimensional development platform: Rhinoceros, version 5 ( http://www.rhino3d.co.uk ). Users select cusps on mandibular and maxillary teeth on three-dimensional digital models. A three-dimensional cubic spline generates a mandibular curve, and a best-fit horizontal mandibular reference plane is produced using a least-squares method. Horizontal distances projected from the shortest three-dimensional distances were subsequently calculated between the maxillary cusps and the mandibular curve to calculate the modified Huddart and Bodenham score. Main Outcome Measures Automatic scoring of digital models using the modified Huddart and Bodenham system produces similar results to manual scoring. Results By standardizing outcome assessment in cleft care, multicenter comparisons for audit and research can be simplified, allowing centers throughout the world to upload three-dimensional digital models or intraoral scans of the dental arches for remote scoring. Thereafter, these data can feed back into the global database on orofacial clefting as part of the World Health Organization's international collaborative “Global Burden of Disease” research project for craniofacial anomalies. Conclusions The automated system facilitates quicker and more reliable outcome assessments by minimizing human errors.
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Jamieson, Marissa D., Alex W. Brady, Kira Tanghe, Thomas O. Clanton i Ingrid Stake. "Anterior-Inferior Tibiofibular Ligament Suture-Tape Augmentation for Isolated Syndesmotic Injuries". Foot & Ankle Orthopaedics 7, nr 1 (styczeń 2022): 2473011421S0026. http://dx.doi.org/10.1177/2473011421s00263.
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Category: Sports; Ankle Introduction/Purpose: Aggressive surgical treatment of isolated syndesmotic injuries has recently gained some traction in the media and sports world. New developments in syndesmotic fixation aim to restore native syndesmotic stability and ankle motion with a goal of returning athletes to sport quickly. However, the best surgical technique is debated. Dynamic repair with a suture- button (SB) can provide an accurate reduction of the syndesmotic space but may alter the rotational kinematics of the fibula. Previous studies have suggested that repair or reconstruction of the anterior-inferior tibiofibular ligament (AITFL) may restore the dynamics of the syndesmosis better than other devices. The purpose of this study was to biomechanically compare SB fixation and augmented repair of the AITLF using suture and suture-tape (ST) in isolated syndesmotic injuries. Methods: Twelve unpaired lower leg specimens underwent biomechanical testing in 6 states: 1) intact, 2) AITFL suture repair alone, 3) AITFL suture repair + ST augmentation, 4) AITFL suture repair + ST augmentation + SB fixation, 5) AITFL suture repair + SB fixation, and 6) complete syndesmotic injury. The testing consisted of subjecting the ankle joint to 6 cycles of 5 Nm internal and external rotation torque under a constant 750 N axial compression load in a dynamic tensile testing machine. A lower level of torque was chosen than in previous studies in order to replicate physiologic motion of everyday activities instead of injury level forces. The spatial relationship between the tibia and fibula and tibia and talus was continuously recorded using a 5-camera motion capture system. Results: AITLF suture repair and suture repair + ST augmentation repair constructs showed no statistically significant change in fibula kinematics during testing compared to the intact state. The suture repair + SB construct showed increased external rotation of the fibula (p<0.001, mean 2.32 degrees) and medial translation (mean 0.72 mm, p= 0.007) or overtightening compared to the intact state. The suture repair + SB + ST augmentation state also showed increased external rotation of the fibula compared to the intact state (p<0.001). Sagittal plane motion of the fibula was not significantly different in the repair states compared to the intact state. None of the repair states restored talus rotation back to the intact state; however, the repairs that utilized suture tape reduced the talus external rotation laxity compared to the complete syndesmotic injury. Conclusion: For isolated syndesmotic injuries without significant fibular displacement, augmentation of the AITFL with suture- tape best restored the rotational profile of the fibula and ankle joint. Suture-button constructs had a tendency to over-tighten and externally rotate the fibula when compared to the intact state. Suture-tape AITFL augmentation may be a good surgical option and alternative to suture-button fixation for isolated syndesmotic disruptions. Further clinical trials are needed to determine the role for suture-tape augmentation of the AITLF in syndesmotic injuries.
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Cai, Laisi, Ye Ma, Shuping Xiong i Yanxin Zhang. "Validity and Reliability of Upper Limb Functional Assessment Using the Microsoft Kinect V2 Sensor". Applied Bionics and Biomechanics 2019 (11.02.2019): 1–14. http://dx.doi.org/10.1155/2019/7175240.
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Objective. To quantify the concurrent accuracy and the test-retest reliability of a Kinect V2-based upper limb functional assessment system. Approach. Ten healthy males performed a series of upper limb movements, which were measured concurrently with Kinect V2 and the Vicon motion capture system (gold standard). Each participant attended two testing sessions, seven days apart. Four tasks were performed including hand to contralateral shoulder, hand to mouth, combing hair, and hand to back pocket. Upper limb kinematics were calculated using our developed kinematic model and the UWA model for Kinect V2 and Vicon. The interdevice coefficient of multiple correlation (CMC) and the root mean squared error (RMSE) were used to evaluate the validity of the kinematic waveforms. Mean absolute bias and Pearson’s r correlation were used to evaluate the validity of the angles at the points of target achieved (PTA) and the range of motion (ROM). The intersession CMC and RMSE and the intraclass correlation coefficient (ICC) were used to assess the test-retest reliability of Kinect V2. Main Results. Both validity and reliability are found to be task-dependent and plane-dependent. Kinect V2 had good accuracy in measuring shoulder and elbow flexion/extension angular waveforms (CMC>0.87), moderate accuracy of measuring shoulder adduction/abduction angular waveforms (CMC=0.69-0.82), and poor accuracy of measuring shoulder internal/external angles (CMC<0.6). We also found high test-retest reliability of Kinect V2 in most of the upper limb angular waveforms (CMC=0.75-0.99), angles at the PTA (ICC=0.65-0.91), and the ROM (ICC=0.68-0.96). Significance. Kinect V2 has great potential as a low-cost, easy implemented device for assessing upper limb angular waveforms when performing functional tasks. The system is suitable for assessing relative within-person change in upper limb motions over time, such as disease progression or improvement due to intervention.
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Blackwell, Corey J., Julia Sarah Wasas, Sean Patrick Flanagan, Bryan A. Norman i Joel Michael Haight. "Grocery shelf stocking tool: analysis of productivity and human factors". International Journal of Productivity and Performance Management 65, nr 4 (11.04.2016): 554–70. http://dx.doi.org/10.1108/ijppm-02-2015-0026.
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Purpose – Grocery store tasks provide many opportunities for efficiency and ergonomic improvements. Shelf stocking is one task that has received considerable attention in recent years as grocery stores seek to remain competitive by stocking shelves in an efficient manner in order to satisfy customers. The purpose of this paper is to detail an analysis performed to evaluate the effectiveness of a grocery store shelf stocking tool. This shelf stocking aid is a device designed to improve the accuracy and efficiency of stocking and fronting shelves in a supermarket or a similar retail environment. Design/methodology/approach – To test the claims that the device actually does improve stocking accuracy, efficiency, and ergonomic soundness, an experiment was conducted to compare the processes of stocking shelves and fronting items on shelves with and without the stocking tool. In creating the realistic conditions of a real-world store environment, extensive inquiry about item stocking and fronting procedures was made by visiting stores and discussing the stocking and fronting tasks with industry experts. Tests were performed at varying combinations of shelf heights, shelf fullness, with and without First-In First-Out processing, and with various merchandise sizes and shapes. Findings – The results indicate that the shelf stocking tool significantly reduces shelf stocking and fronting time. The ergonomic merits of the tool were also analyzed. A Rapid Upper Limb Assessment (RULA) was performed to evaluate biomechanical and postural stresses experienced by a shelf stocker as they stock and front store shelves. It appears that the largest contributor to higher-than-expected RULA scores is extensive upper torso bending in the sagittal plane at the L5 S1 disc position. This is exacerbated as the stocker reaches lower shelves and bends forward to reach under the shelf directly above the item being stocked or fronted. Research limitations/implications – Only three tall and five short items were used in testing. More testing is needed to draw conclusions about stacking items. Cumulative fatigue effects were not tested nor were the locations of specific physical discomfort. Testing was not done to examine simultaneously fronting two rows with the shelf stocking tool. Testing was not done to simulate the use of a step stool, including moving and repositioning the step stool for manual restocking and fronting on high shelves. The step stool handling would improve relative performance of the shelf stocking tool because the tool eliminates the need for a step stool. Practical implications – Grocery store shelf stocking associates are at risk of developing cumulative trauma type injuries from awkward posture that they have to use when stocking shelves. With many small items on a shelf that are continually becoming disheveled as customers purchase the items, there are significant inefficiencies in continually arranging and rearranging the items as well as adding new. The analysis of a tool of the type tested here has shown that the use of a simple tool such as the one tested can go a long way to improving both of these elements of the stocking and fronting task. Originality/value – While the shelf stocking tool is not necessarily a remedy for bending, it appears to reduce more pronounced bending than what is required without it. For stocking or fronting upper shelves, it also appears to reduce the extensive reaches (the second most stressful contributor to the high RULA scores). This approach to stocking and fronting shelves has helped to verify the idea that a tool such as this can help to improve not only the speed and efficiency at which the task is accomplished it can also reduce the stress on the back and shoulders during this tedious task.
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Wassink, Casper, Marc Grenier, Michael Sirois, Anne-Marie Allard i Jonathan Berthier. "Eddy Current Testing Basics and Innovation". Materials Evaluation 79, nr 4 (1.04.2021): 360–67. http://dx.doi.org/10.32548/2021.me-04218.
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Eddy current testing is considered a theoretically challenging technique. Out of all the different nondestructive testing (NDT) methods, the electromagnetic testing (ET) method (of which eddy current testing is a technique) is probably the most difficult for understanding theory. This is perhaps why the last Materials Evaluation Back to Basics paper on eddy current testing is from 2006, which is a long time ago given the amount of innovation in the technique that has taken place since then (Hansen and Peoples 2006). In this paper we will show what has changed due to recent innovations. We first will present the physics, and then explain how modern equipment assists the user in distinguishing between different physical phenomena. Although this paper is on conventional eddy current testing, we will also mention some other ET techniques along with their advantages and disadvantages.
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Mironov, S. P., G. M. Burmakova i A. I. Krupatkin. "Lumbar pain in athletes and ballet dancers: pathology of the lumboiliac ligament". N.N. Priorov Journal of Traumatology and Orthopedics 8, nr 4 (4.03.2022): 14–21. http://dx.doi.org/10.17816/vto100357.
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The experience in examination and treatment of 21 patients with low back pain resulted in ligamentum iliolumbale pathology is presented. Clinical neurologic examination takes significant place in diagnosis of ligamentopathy. Correct interpretation of provocated testing data and pseudoradicular syndrome allows to avoid the diagnostic mistakes and inadequate treatment.
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Hungerford, John C., i Baron P. Johnson. "Exploratory Biomechanical Studies to Determine Worker Fitness for Manual Material Handling Tasks". Proceedings of the Human Factors Society Annual Meeting 31, nr 4 (wrzesień 1987): 452–56. http://dx.doi.org/10.1177/154193128703100415.
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This paper presents the results from two biomechanical studies that examined the effects of loading on the L5/S1 area of the lower spine. The objective of these exploratory studies was to determine whether subject, cardiovascular, and isometric and isotonic strength variables could be used to determine a worker's risk potential for back injury. The first study examined trunk velocity and torque developed in movement against a 30 lb. resistive load for two groups of people: (1) normals (no back pathology), and (2) abnormals (people with physician-diagnosed back pathology). Significant differences were found between these two groups for back torque and velocity measures. People with back pathology developed less torque and were slower in their movements. Discriminant analysis provided an 82% correct classification for normals and abnormals using velocity and torque measurements. The second investigation studied only people with back pathology and its objective was to explore the sensitivity of the testing procedure to distinguish between different degrees of back pathology. The purpose of these studies was to develop measures that could be used to screen and place people in jobs so they would not be at risk for back injury. Further work will aim at: (1) improving the discriminant function used in the first study, (2) searching for additional measures predictive of back injury risk potential, (3) reducing the resistive loads used in testing, and (4) studying non-symmetrical loading effects on the spine.
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McCallum, Lee, i Christine Coombe. "An Interview with Glenn Fulcher: Looking Back and Moving Forward". Language Teaching Research Quarterly 29 (lipiec 2022): 6–19. http://dx.doi.org/10.32038/ltrq.2022.29.02.
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The interview took place on 16th February 2022 at 11:00am (GMT) via Zoom. The interview focused on three central themes of Professor Fulcher’s work in language assessment: (i) Reflecting on his career as an educator and scholar, (ii) Experiences and lessons learned when working with industry testing companies, and (iii) Future opportunities and challenges for the language assessment community. The interview was transcribed by Dr. Lee McCallum
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KANG, SEONG-HOON, YOUNG-SEON LEE i JUNG-HWAN LEE. "SPRING-BACK CHARACTERISTICS OF GRAIN-REFINED MAGNESIUM ALLOY ZK60 SHEET". International Journal of Modern Physics B 22, nr 31n32 (30.12.2008): 6076–81. http://dx.doi.org/10.1142/s0217979208051601.
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In this work, the effect of grain size on the spring-back characteristic was investigated by carrying out air-bending test using magnesium alloy ZK60 sheet with thickness of 0.5 mm at the various temperatures from room temperature to 300 °C. The angles of the bent specimen before and after unloading were measured in order to quantify spring-back amount. It was found out from the bending tests that when the specimens with grain sizes of 14.66 and 60.71 µm were bent by 90°, the amount of spring-back was relatively small at the testing temperature range and was in the range between -2.5° and 2.5°. On the other hand, the spring-back amount dramatically increased at room temperature and phenomenon of spring-go was observed at high temperature when the specimen with submicro grain size of 0.98 µm was bent by 90°. From this finding, it was confirmed that the different spring-back characteristics according to the grain size takes place and thus the grain size of material is one of the important factors which have an effect on the spring-back.
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Lane, Becca, i Tom Kazmierowski. "Implementation of Cold In-Place Recycling with Expanded Asphalt Technology in Canada". Transportation Research Record: Journal of the Transportation Research Board 1905, nr 1 (styczeń 2005): 17–24. http://dx.doi.org/10.1177/0361198105190500102.
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Cold in-place recycling (CIR) is a pavement rehabilitation method that processes an existing hot-mix pavement, sizes it, mixes in additional asphalt cement, and lays it back down without off-site hauling and processing. The added asphalt cement is typically emulsified asphalt. A recent development in CIR technology is the use of expanded (foamed) asphalt rather than emulsified asphalt to bind the mix. This combination of CIR and expanded asphalt technologies is termed cold in-place recycled expanded asphalt mix (CIREAM). The Ministry of Transportation Ontario (MTO) constructed a CIREAM trial section on Highway 7 in July 2003. The 5-km CIREAM trial section was constructed adjacent to an 8-km section on which conventional CIR was performed. CIREAM placement resulted in a smooth, hard, uniform surface that provided an excellent platform for paving operations. The CIREAM placement progressed in a continuous and efficient manner, with 5 km placed over a 3-day period. Indirect tensile strength testing was carried out on both materials during construction. Falling weight deflectometer (FWD) testing and evaluation of pavement roughness and rutting by the use of MTO's automatic road analyzer (ARAN) were carried out. Resilient modulus testing of core samples of the CIR material and CIREAM was also carried out. The results of the FWD, ARAN, and resilient modulus tests indicated that the CIR and CIREAM pavements were performing similarly. A field review 1 year after construction showed no discernible distortion, rutting, or cracking. On the basis of short-term results, CIREAM appears to be an acceptable in-place recycling and rehabilitation strategy that provides an economical alternative to conventional CIR, reduces curing time, and extends the construction season.
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Stegner, Heather, i Nikki Fotheringham. "Research and Testing Lead to Historic Code Change". Forest Products Journal 72, nr 4 (1.10.2022): 226–34. http://dx.doi.org/10.13073/2376-9637-72.4.226.
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Abstract Simply substituting wood for conventional building materials could provide almost a tenth of the global carbon emission reductions needed to meet 2030 goals. However, while structural light-frame wood products are the go-to building material in the United States for low-rise residential construction, capturing over 90 percent of the market, any kind of wood-frame construction at the time under examination was limited to 5 stories and 85 feet in height. These story and height limitations dated back decades and prevented the design and construction of larger and taller buildings. In 2014, the American Wood Council (AWC) began developing a plan to expand these limits, but recognized it would require the International Building Code, the predominant model code adopted in most local and state jurisdictions in the United States, to embrace a new type of construction: fire-resistance-rated tall mass timber.
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Balmforth, D. J., J. R. Blanksby, C. Brown i C. Rogerson. "Development and testing of a new design procedure for the control of aesthetic pollutants at combined sewer overflows". Water Science and Technology 39, nr 2 (1.01.1999): 53–60. http://dx.doi.org/10.2166/wst.1999.0083.
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Two research projects identified the need for a new design guide and software to facilitate the design of combined sewer overflows. The purpose of the design guide and software is to enable the selection of the most cost effective arrangement of overflow and screens according to local circumstances. Strategies were developed to minimise the risk of those testing the design guide and software. Tests took place on a number of projects, one of which is the subject of an ongoing pre and post construction appraisal. The experience gained from the test projects is being fed back into the software development.
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Diewald, Axel, Clemens Kurz, Prasanna Venkatesan Kannan, Martin Gießler, Mario Pauli, Benjamin Göttel, Thorsten Kayser, Frank Gauterin i Thomas Zwick. "Radar Target Simulation for Vehicle-in-the-Loop Testing". Vehicles 3, nr 2 (19.05.2021): 257–71. http://dx.doi.org/10.3390/vehicles3020016.
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Automotive radar sensors play a vital role in the current development of autonomous driving. Their ability to detect objects even under adverse conditions makes them indispensable for environment-sensing tasks in autonomous vehicles. As their functional operation must be validated in-place, a fully integrated test system is required. Radar Target Simulators (RTS) are capable of executing end-of-line, over-the-air validation tests by looping back a received and afterward modified radar signal and have been incorporated into existing Vehicle-in-the-Loop (ViL) test beds before. However, the currently available ViL test beds and the RTS systems that they consist of lack the ability to generate authentic radar echoes with respect to their complexity. The paper at hand reviews the current development stage of the research as well as commercial ViL and RTS systems. Furthermore, the concept and implementation of a new test setup for the rapid prototyping and validation of ADAS functions is presented. This represents the first-ever integrated radar validation test system to comprise multiple angle-resolved radar target channels, each capable of generating multiple radar echoes. A measurement campaign that supports this claim has been conducted.
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Stubbs, Spencer, i Jonathan Colton. "The Design of a Mechanized Onion Transplanter for Bangladesh with Functional Testing". Agriculture 12, nr 11 (28.10.2022): 1790. http://dx.doi.org/10.3390/agriculture12111790.
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Rising labor costs and the inefficient manual methods of cultivating red onions in Bangladesh contribute to the country’s failure to meet is own demand. Mechanizing the process of transplanting red onion seedlings will reduce the manual labor required while increasing crop yields. This paper provides an initial study of a proposed mechanized onion transplanter designed to attach to the back side of a two-wheel tractor with power tiller operated-seeder, commonly used in Bangladesh. Testing of a prototype made from these designs proves that the design is functional but requires further development for commercial/widespread use.
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Sarian, Antranig Arek. ""No Going Back": The Telltale Model as Thought Experiment". Eludamos: Journal for Computer Game Culture 9, nr 1 (19.09.2018): 17–32. http://dx.doi.org/10.7557/23.6163.
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Since the release of The Walking Dead in 2012, the "Telltale Model" of interactive narrative has attracted a lot of criticism for providing choices that 'don't matter'. This paper is a response to this discussion taking place both in academia and popular games culture. While Telltale's choices indeed 'don't matter' this overlooks the ways in which they actually function. The Telltale Model works in a way that is analogous to the philosophical thought experiment. It presents a sequential series of moral dilemmas that all communicate a common theme. The penultimate choice in The Walking Dead Season 2 Episode 5: No Going Back (2013) performs as a final lesson - testing the player to see if they have properly internalised the themes of the series. It then responds not to the accumulated memory of their choices, but to how they respond to the final 'test' that bookends the series’ many ethical dilemmas. Telltale's choices may not have any long-term consequences, but they do serve an informative pedagogical function - just don't expect Kenny to ever "remember that".
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Muminov, R. A., M. N. Tursunov, Kh Sabirov, Sh N. Abilfayziyev, B. A. Yuldoshov i S. F. Toshpulatov. "Testing of crystalline silicon-based photoelectric and photothermal batteries in real climate conditions and comparison of parameter changes". Journal of Physics: Conference Series 2388, nr 1 (1.12.2022): 012128. http://dx.doi.org/10.1088/1742-6596/2388/1/012128.
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Abstract The article examines the changes in electrical parameters of three types of photovoltaic batteries (PV) and photothermal batteries (PVT) based on them, installed on a portable device with the increased intensity of solar radiation using reflective planes. In this case, without changing the position of the PV and PVT in the device, like the “network” stations, it was set so that the solar radiation falls vertically, as in the time of the rising of the sun, directed to the south. This natural experiment served two purposes. The first is to determine the optimal type for the climate when the various types of PVs available in the local commercial market are used in hot climates. Second, the results of determining and comparing the changes in parameters and energy efficiency of PV and PVT with the same base and capacity at the same time under the same conditions are presented. From the results of the experimental tests, it was clear that the best indicators in terms of short-circuit current, open circuit voltage and power in hot climates are monocrystalline PV and its base PVT. Among the PVs, the lowest values were observed in front and black back coating photoelectric battery. Among the PVTs, it was observed in the polycrystalline silicon photothermal battery. When all types of PVTs were cooled by passing water with a temperature of 18-20°C, sharp electrical changes were observed in monocrystalline silicon with a black back coating. The conclusion from the results of this change is that the use of black back coating photoelectric battery in cold climate regions leads to higher efficiency. Compared to conventional PV, PVT has been observed to generate 1.3-1.4 times more electricity depending on the type of material.
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Iltaf, Asim, Massab Junaid, Fahd N. khan i Azhar Hussain. "Microstructure, mechanical properties, residual stresses and texture analysis of Ti-5Al-2.5Sn alloy weldments obtained using electron beam of different oscillation patterns". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, nr 17 (6.04.2020): 3484–96. http://dx.doi.org/10.1177/0954406220916550.
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Electron beam welding was used for welding of Ti-5Al-2.5Sn alloy using three types of beam oscillation patterns, i.e. elliptical, concentric circles and arrow shape waveform. The influence of these patterns on microstructure, mechanical properties and residual stresses was investigated using optical microscopy, electron back scattered diffraction, scanning electron microscopy, microhardness measurement, residual stress measurement, impact testing, smooth and notch tensile testing. A partial martensitic transformation was observed in the fusion zone of all the three welding patterns. The fusion zone of arrow pattern weldment exhibited approximately 16% and 1.2% higher hardness than elliptical and concentric circles patterns, respectively. Owing to an improved texture of the basal and prismatic planes in the cross-weld direction, the arrow pattern showed improved strength, reduced tensile residual stresses than elliptical and concentric circles pattern. Elliptical pattern showed superior elongation characteristics as well as increased impact strength as compared to the arrow and concentric circle patterns.
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Dovgal, A. H., L. B. Pryimak i V. V. Varijukhno. "Wear Resistance Research and Its 2-factor Modeling of Nanoscaled Silicon Carbide Detonation Coatings". Problems of Tribology 28, nr 2/108 (22.06.2023): 6–14. http://dx.doi.org/10.31891/2079-1372-2023-108-2-6-14.
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This research is related to the spheres of wearproof coating testing. The SiC coating has been deposited on the medium carbon steel using detonation deposition using the magnet coil flux of back direction. It has been established that only nanoscaled particles are deposited on the surface which had been accumulated in aggregates of different shape. The structure of the obtained coating has been thoroughly researched on the electronic microscope in previous publication. The obtained coating has been developed for testing on the friction bench modeling the friction process that is taking place in the couple of main and rod journals of internal combustion engines. The coating has also the corrosion protection properties. The nanoscaled coating on mild carbon steel had been tested under specified conditions and their friction surfaces had been researched on electronic microscope with the view of determination of wear mechanism. The two-factor modeling of the wear rate and friction factor has been done and three-dimensional diagrams have been plotted and analyzed.
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de Zwart, Melissa, i Dale Stephens. "Non-Military Space Testing in the Woomera Prohibited Area: Opportunities for the Australian Space Industry?" Federal Law Review 45, nr 1 (marzec 2017): 39–64. http://dx.doi.org/10.1177/0067205x1704500103.
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The Australian Civil Space Industry is poised at a crucial moment in its history. Careful strategic decisions need to be made regarding whether Australia will continue to take a back seat in the space race or whether it will join the growing space technology industry, providing major opportunities for Australian innovators. This cannot occur if the current legal and regulatory frameworks do not facilitate research activities and investment. The Australian Government is currently reviewing the Space Activities Act 1998 (Cth) and the Space Activities Regulations 2001 (Cth). This article will consider the unique role played by the Woomera Prohibited Area in the development and testing of launch technology and undertake an assessment of whether the Woomera Range (and by extension Australia) may once again play an important role in the research, development and testing of space technology. The article will place the legal restrictions regarding access to and use of the Woomera Range within the context of the proposed revision of the Australian legislation regulating civil space activities.
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Goh, Jia Quan, Abdul Rashid Mohamed Shariff i Nazmi Mat Nawi. "Application of Optical Spectrometer to Determine Maturity Level of Oil Palm Fresh Fruit Bunches Based on Analysis of the Front Equatorial, Front Basil, Back Equatorial, Back Basil and Apical Parts of the Oil Palm Bunches". Agriculture 11, nr 12 (23.11.2021): 1179. http://dx.doi.org/10.3390/agriculture11121179.
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The quality of palm oil depends on the maturity level of the oil palm fresh fruit bunch (FFB). This research applied an optical spectrometer to collect the reflectance data of 96 FFB from unripe, ripe, and overripe classes for the maturity level classification. The spectrometer scanned the FFB from different parts, including apical, front equatorial, front basil, back equatorial, and back basil. Principal component analysis was carried out to extract principal components from the reflectance data of each of the parts. The extracted principal components were used in an ANOVA test, which found that the reflectance data of the front equatorial showed statistically significant differences between the three maturity groups. Then, the collected reflectance data was subjected to machine learning training and testing by using the K-Nearest Neighbor (KNN) and Support Vector Machine (SVM). The front equatorial achieved the highest accuracy, of 90.6%, by using SVM as classifiers; thus, it was proven to be the most optimal part of FFB that can be utilized for maturity classification. Next, the front equatorial dataset was divided into UV (180–400 nm), blue (450–490 nm), green (500–570 nm), red (630–700 nm), and NIR (800–1100 nm) regions for classification testing. The UV bands showed a 91.7% accuracy. After this, representative bands of 365, 460, 523, 590, 623, 660, 735, and 850 nm were extracted from the front equatorial dataset for further classification testing. The 660 nm band achieved an 89.6% accuracy using KNN as a classifier. Composite models were built from the representative bands. The combination of 365, 460, 735, and 850 nm had the highest accuracy in this research, which was 93.8% with the use of SVM. In conclusion, these research findings showed that the front equatorial has the better ability for maturity classification, whereas the composite model with only four bands has the best accuracy. These findings are useful to the industry for future oil palm FFB classification research.