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Journal articles on the topic 'Load testing purposes'
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1
Huang, Yu Yang, Laszlo Horvath, and Péter Böröcz. "Measurement and Analysis of Industrial Forklifts Vibration Levels for Unit Load Testing Purposes." Applied Sciences 11, no. 7 (March 24, 2021): 2901. http://dx.doi.org/10.3390/app11072901.
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Forklifts are one of the most common types of material handling equipment used in warehouses and distribution centers. Vibration generated by forklifts may have an effect on the performance of unit loads and product damage rates. Historical research projects have focused predominantly on the measurement of vibration for over-the-road transportation. Thus, there is still a lack of understanding of the level of vibration caused by forklifts. The goal of this study was to understand how the vibration that is experienced by unit loads while being transported by forklifts is affected by factors such as speed, road condition, unit load weight, type of forklift, and sensor location. For this study, power spectral density (PSD) measurements were collected using a Lansmont Saver 9X30 data logger. Vibration levels were measured for three different industrial forklifts on two different surface types. The forklifts were driven at two different speeds while carrying two different unit load weights. For all of these conditions, the vibration levels were measured at the forklift carriage, at the back of the fork tine heel, and at the fork tine tips. The results obtained show that the highest vibrational intensity occurred at 3–4 Hz, while the highest overall Grms value observed was 0.145 G2/Hz (between 1–200 Hz). An increase in the forklift speed caused an increase in vibration intensity. In contrast, an increase in the unit load weight carried by the forklift caused a decrease in vibration intensity. Among the three forklifts studied, the gas-powered forklift had the highest vibration intensity, and all forklifts, when driven on asphalt, experienced more vibration.
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Permana, E., and Yayat. "Design and Development of Impact Load Sensor for Dynamic Testing Purposes." IOP Conference Series: Materials Science and Engineering 288 (January 2018): 012060. http://dx.doi.org/10.1088/1757-899x/288/1/012060.
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Sekuła, Krzysztof, and Andrzej Świercz. "Weigh-in-Motion System Testing." Key Engineering Materials 518 (July 2012): 428–36. http://dx.doi.org/10.4028/www.scientific.net/kem.518.428.
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The paper presents some results of research on the Weight-in-motion (WIM) system. The device is used for identification of loads on the road surface generated by traveling vehicles. The proposed approach utilizes the piezoelectric measurement techniques to monitor strain development in a deformable body and eventually these measurements are used for tire-pavement load identification. An advantage of the proposed concept is that no additional limitation for a vehicle velocity and direction is required in order to make the measurement feasible. The device allow to identify many parameters which can be stored for statistical and planning purposes. When an overload or an exceed in speed limit is detected the data can be sent for penalization purposes. The research includes a computer simulation of the bending plate detector using the Finite Element Method (FEM). Its objective is to validate the concept as well as to test some factors which are important with respect to the proposed load identification methodology. An experimental research involved field tests on the WIM system using a bending plate detector and inductive loops to detect a vehicle.
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Jin, Sheng Li, Harald Harmuth, and Dietmar Gruber. "Creep Testing of Refractories at Service Related Load Levels and Application for Material Simulation." Advances in Science and Technology 92 (October 2014): 221–25. http://dx.doi.org/10.4028/www.scientific.net/ast.92.221.
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During the operation of industrial vessels at high temperatures both elastic and inelastic behaviour of refractories may occur under intense thermomechanical loads. The latter one brings about an irreversible strain, which may cause mechanical failure of refractories and be responsible for the opening of joints. Besides material failure under tensile or shear loads, creep of refractories also may contribute to the occurrence of the irreversible strains. For quantitative assessment of the thermomechanical behaviour of an industrial vessel lining by the simulations, the accurate determination and description of creep behaviour of refractories at service related load levels is of importance. In this paper, a newly developed high temperature compressive creep testing equipment is introduced. Compared with conventional creep testing machines it enables the application of higher load levels as they occur under service conditions. A general testing procedure and displacement/time curves for various temperatures and loads are shown. For simulation purposes a Norton Bailey type creep law representing strain hardening is identified from the test results. An inverse evaluation procedure is performed for this purpose which exhibits high efficiency and robustness.
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Sike, Wang, Guo Yu, Li Jun, Xia Tian, and Lei Ming. "Gateway Electric Energy Meter Measurement System Based on Independent Load Control." MATEC Web of Conferences 175 (2018): 03030. http://dx.doi.org/10.1051/matecconf/201817503030.
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In order to meet the efficiency and timeliness measurement requirements for electric energy meters with different specifications in gateway energy meter testing laboratory, a new testing system based on multithreading technique is proposed here. Through identifying the different wiring modes of electric meters, integrating with newly designed CT based on zero-flux compensation principle and applying creative multi-channel load control for different tap positions, the system can provide differentiated testing loads for different meters at the same time. Meanwhile, electric energy pulses required by different electric energy meters can be worked out by one standard meter. Consequently, completely independent measurement for different meters will be achieved with improved timeliness substantially. Through simulation tests for different electric energy meters, and comparison for calculated testing time, the initial design purposes are tested and verified.
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Gola, M. M., and A. Gugliotta. "Some Experimental Results concerning the Mechanical Coupling in Endoprosthetics." Engineering in Medicine 16, no. 1 (January 1987): 23–27. http://dx.doi.org/10.1243/emed_jour_1987_016_007_02.
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The work continues and completes an earlier work (Gola and Gugliotta, 1982). The refined model of a special transducer-stem is here used, after implantation in a dry bone, for two purposes. First, to confirm a recent numerical finding which states a stress equivalence between physiological loads on a prosthesis-femur system and a simplified load condition, more desirable for testing purposes. Second, the separate effects of throchanteric muscle forces and of femural head forces on the stresses in the prosthetic stem are shown at various angles; superposition of effects compares well with the physiological loading case.
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Nsengiyumva, Gabriel, and Yong-Rak Kim. "Effect of Testing Configuration in Semi-Circular Bending Fracture of Asphalt Mixtures: Experiments and Statistical Analyses." Transportation Research Record: Journal of the Transportation Research Board 2673, no. 5 (April 7, 2019): 320–28. http://dx.doi.org/10.1177/0361198119839343.
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The semi-circular bending (SCB) test is a simple, efficient, and easily applicable method in the pavement community to characterize fracture behavior. This makes it widely used as a quality control (QC) and quality assurance (QA) approach at several transportation agencies. However, public–private testing laboratories have implemented SCB test methods using different load-support fixture conditions with an insufficient understanding of how the conditions affect the results and testing variability. This could be particularly problematic when using SCB test results obtained from different load-support fixtures as QC–QA (or pass/fail) purposes. This study investigated the effect of SCB testing configurations on test results and their variability by conducting tests using six different load-support fixtures. Several fracture-related indicators such as fracture energy, flexibility index, peak load, and the coefficient of the cracking index resulting from the six different load-support fixtures were compared. Test results and statistical analyses showed that SCB tests generally showed repeatable results, whereas load-support fixtures can affect test results and their repeatability, thus care should be taken when choosing a testing fixture. The addition of roller springs generally increased the variability of the test results. It appears that the mid-span jig was detrimental to testing repeatability, and friction at the support should be avoided because it can erroneously increase fracture resistance with a higher variability.
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Moens, N., R. Runciman, D. Holmberg, and T. Gibson. "Evaluation of a short glass fibre-reinforced tube as a model for cat femur for biomechanical testing of orthopaedic implants." Veterinary and Comparative Orthopaedics and Traumatology 21, no. 03 (2008): 195–201. http://dx.doi.org/10.1055/s-0037-1617361.
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SummaryThe biomechanical testing of tubes made of third generation short glass fibre-reinforced (SGFR) material approximating cat femurs was performed in order to determine their suitability as cat femur surrogates for the biomechanical testing of orthopaedic implants. The tubes were tested in compression, three-point bending, notch testing, and screw pullout. Thin walled (B1-tubes) had a 13% lower maximum load to failure, a 19% higher maximum strength and a 13% lower elastic modulus compared to cat femurs tested in compression. B1-tubes maximum load to failure in threepoint bending and screw pullout strength were considerably lower compared to cat femurs (29% and 63%, respectively). Notch testing was not performed on B1-tubes due to low bending strength. Thicker walled (B2-tubes) had a 23% higher maximum load to failure, a 10% higher maximum strength and a 21% lower elastic modulus compared to cat femurs tested in compression. The comparison of B2-tubes and cat femurs in three-point bending revealed a 7% increase in maximum load to failure for the B2-tubes. Drilled B2-tubes (notch testing) were weaker with a 30% lower load to failure compared to cat femurs. A screw pullout comparison of B2-tubes and cat femurs revealed a 2% increase in maximum load to failure for the B2-tubes. These tubes were intended to provide a model as a suitable surrogate for cat femurs for testing the bending strength of various orthopaedic constructs involving plates and screws. Testing revealed that third generation SGFR tubes were not suitable for these purposes and emphasizes the need to carefully evaluate the suitability of any model.
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Fleming, P. R., E. Faragher, and C. D. F. Rogers. "Laboratory and Field Testing of Large-Diameter Plastic Pipe." Transportation Research Record: Journal of the Transportation Research Board 1594, no. 1 (January 1997): 208–16. http://dx.doi.org/10.3141/1594-24.
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Flexible plastic pipe is increasingly being used in the United Kingdom for drainage and ducting (conduit) purposes. This increase in use is leading to the introduction of larger-diameter pipes. The U.K. Department of Transport (DoT) uses a recently developed, theoretical method to specify installation conditions in place of traditional techniques (e.g., Spangler’s Iowa method). The DoT design method is outlined. The extensive program of laboratory and field testing carried out at Lough-borough University to determine the performance of plastic pipes under a range of loading conditions that may be expected in practice is then described. Laboratory test results compared well with the results obtained in the field once the different boundary conditions were accounted for, thereby validating the laboratory test methods by suggesting how allowance for field conditions can be made. Some reference is made to the shapes of deformation (determined from circumferential strain data) and the effect of installation conditions upon them. Pipe deformations were found to be well within acceptable, conservative limits under all load regimens, and near equilibrium of the pipe-soil system was established relatively quickly following application of a static or a dynamic load sequence to it.
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Rehman, Attique Ur, Tek Tjing Lie, Brice Vallès, and Shafiqur Rahman Tito. "Non-Intrusive Load Monitoring of Residential Water-Heating Circuit Using Ensemble Machine Learning Techniques." Inventions 5, no. 4 (November 23, 2020): 57. http://dx.doi.org/10.3390/inventions5040057.
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The recent advancement in computational capabilities and deployment of smart meters have caused non-intrusive load monitoring to revive itself as one of the promising techniques of energy monitoring. Toward effective energy monitoring, this paper presents a non-invasive load inference approach assisted by feature selection and ensemble machine learning techniques. For evaluation and validation purposes of the proposed approach, one of the major residential load elements having solid potential toward energy efficiency applications, i.e., water heating, is considered. Moreover, to realize the real-life deployment, digital simulations are carried out on low-sampling real-world load measurements: New Zealand GREEN Grid Database. For said purposes, MATLAB and Python (Scikit-Learn) are used as simulation tools. The employed learning models, i.e., standalone and ensemble, are trained on a single household’s load data and later tested rigorously on a set of diverse households’ load data, to validate the generalization capability of the employed models. This paper presents a comprehensive performance evaluation of the presented approach in the context of event detection, feature selection, and learning models. Based on the presented study and corresponding analysis of the results, it is concluded that the proposed approach generalizes well to the unseen testing data and yields promising results in terms of non-invasive load inference.
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Li, Gu, Zi Ming Fu, Jie Feng Yan, Bing Wen Li, and Zhi Rong Cen. "Research the Test Method of the Voltage Transformer Secondary Load in the Three-Phase Three-Wire Electric Energy Metering Device." Applied Mechanics and Materials 687-691 (November 2014): 3110–15. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.3110.
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This paper analyzes and studies the definition of the voltage transformer secondary load, examines the practical purposes of the measured values of the voltage transformer secondary load, and presents a variety of testing methods to analyze and compare the differences. This paper gives the test methods of the voltage transformer secondary load when the connection of the voltage transformer is the Y / Y in a three-phase three-wire power supply system, filling the blank of this type of test method in the industry. When other units within the industry carry out such work, the conclusions of this paper are available for reference, and the conclusions of this paper can be referred when drafting relevant regulations in the future.
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Pegg, Jane E., Jennifer E. Rawlinson, Jennifer L. Kelley, and Eric Monnet. "Cadaveric Evaluation of Load to Failure in Canine Gingiva Apposed With Varied Suture Patterns Using Poliglecaprone 25." Journal of Veterinary Dentistry 38, no. 1 (March 2021): 8–17. http://dx.doi.org/10.1177/08987564211010940.
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The purpose of the study was to determine the effect of suture pattern and repair length on the load to failure in an ex vivo canine gingival model. Healthy mandibular gingiva and mucosa were harvested from fresh cadavers euthanized for purposes unrelated to the study. Samples were randomly assigned by length and pattern. Lingual and buccal free gingival margins were apposed using a simple interrupted (SI), cruciate (XT), simple continuous (SC), or unidirectional knotless continuous barbed suture (SF) closure technique with USP 4-0 poliglecaprone 25i, ii applied over 2 lengths (3 cm and 6 cm). A custom template was used to ensure uniform suture bite application. Surgical time was recorded. Using a soft tissue mechanical testing frame, samples were tensioned to failure. Testing was video recorded and reviewed in conjunction with the tension trace data for tension at initial failure (Tfail) and maximum tension sustained (Tmax). Two factor ANOVA by length and pattern was performed followed by individual one way T-tests. Statistically significant findings were XT-SC-SF patterns were quicker to perform than SI. SF was more likely to fail by suture breakage than tissue tearing, and SF withstood less tension at the 3 cm length than SI-XT-SC. No significant difference was detected in Tmax or Tfail between SI and SC or XT. The study demonstrates that SC and XT are comparable to SI in tension resistance and faster to perform suggesting that SC and XT could replace SI for extraction site closure although further in vivo testing is required.
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Boivin, Guy. "Recent Developments in Viral Load Measurements in Human Herpesviruses." Canadian Journal of Infectious Diseases 10, suppl c (1999): 33C—40C. http://dx.doi.org/10.1155/1999/965245.
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Recent developments in molecular biology have allowed precise quantitative analysis of herpesvirus DNA in many biological fluids. Th is paper reviews the clinical utility of performing quantitative polymerase chain reaction testing for herpesviruses. In particular, the assessment of the cytomegalovirus (CMV) DNA load in blood with regard to the development of CMV disease in immunocompromised patients is discussed in greater detail. Relevant information exists to support measuring the CMV burden in the blood of AIDS and transplant patients for diagnostic and treatment monitoring purposes, and, to a lesser extent, to envision the monitoring of the circulating Epstein-Barr virus load for the prevention of pose-transplant lymphoproliferative disorders. On the ocher hand, there are controversial data on the clinical utility of measuring the herpes simplex virus (HSV) load in cerebrospinal fluid of patients with HSV encephalitis and on the relationship between the human herpesvirus 8 DNA load in diverse biological fluids and the presence of Kaposi's sarcoma. There is a paucity of information about the clinical impact of quantifying the other human herpesviruses (varicella-zoster virus, and human herpesviruses 6 and 7).
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Alnuaim, A. M., M. H. El Naggar, and H. El Naggar. "Performance of micropiled raft in clay subjected to vertical concentrated load: centrifuge modeling." Canadian Geotechnical Journal 52, no. 12 (December 2015): 2017–29. http://dx.doi.org/10.1139/cgj-2014-0448.
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The overall behavior of a micropiled raft foundation (MPR) system is similar to a piled raft foundation where the load is transferred by both the raft and micropiles. However, there is no guidance available regarding the design of MPRs or indication of their performance. In this study, geotechnical centrifuge testing was conducted to investigate the behavior of MPR foundations in clay and evaluate their performance characteristics. The study evaluated the performance of MPRs compared to the isolated raft in terms of raft total and differential settlements; raft contact pressure; raft bending moment; and load sharing between the raft and the micropiles. The results showed that for the MPR configuration considered in the study, the raft carried 48% of the applied load. It was found that the Poulos–Davis–Randolph (PDR) method can be used to evaluate the performance of MPR for preliminarily design purposes with approximately 17% error.
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Bujnowski, Grzegorz, and Jakub Smołka. "Java and Kotlin code performance in selected web frameworks." Journal of Computer Sciences Institute 16 (September 30, 2020): 219–26. http://dx.doi.org/10.35784/jcsi.2025.
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This paper discusses the issue of comparing Java and Kotlin technologies based on the web application framework. The criteria taken into account for testing purposes are: execution time, memory usage, CPU load, database response in set time. A series of tests and their in-depth comparative analysis are carried out. For this case, tests and code analysis were carried out to draw comparative conclusions. The performance in terms of web frameworks, database response speed and tests implementation in different languages - in all these Kotlin proved to be less efficient. There is no significant difference between CPU load between individual easurements, the difference does not exceed 2%. Implementation in the Kotlin language has never achieved the best result in any group of measurements.
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Marsalek, Pavel, Martin Sotola, David Rybansky, Vojtech Repa, Radim Halama, Martin Fusek, and Jiri Prokop. "Modeling and Testing of Flexible Structures with Selected Planar Patterns Used in Biomedical Applications." Materials 14, no. 1 (December 30, 2020): 140. http://dx.doi.org/10.3390/ma14010140.
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Flexible structures (FS) are thin shells with a pattern of holes. The stiffness of the structure in the normal direction is reduced by the shape of gaps rather than by the choice of the material based on mechanical properties such as Young’s modulus. This paper presents virtual prototyping of 3D printed flexible structures with selected planar patterns using laboratory testing and computer modeling. The objective of this work is to develop a non-linear computational model evaluating the structure’s stiffness and its experimental verification; in addition, we aimed to identify the best of the proposed patterns with respect to its stiffness: load-bearing capacity ratio. Following validation, the validated computational model is used for a parametric study of selected patterns. Nylon—Polyamide 12—was chosen for the purposes of this study as an appropriate flexible material suitable for 3D printing. At the end of the work, a computational model of the selected structure with modeling of load-bearing capacity is presented. The obtained results can be used in the design of external biomedical applications such as orthoses, prostheses, cranial remoulding helmets padding, or a new type of adaptive cushions. This paper is an extension of the conference paper: “Modeling and Testing of 3D Printed Flexible Structures with Three-pointed Star Pattern Used in Biomedical Applications” by authors Repa et al.
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Wu, T. W. "Microscratch and load relaxation tests for ultra-thin films." Journal of Materials Research 6, no. 2 (February 1991): 407–26. http://dx.doi.org/10.1557/jmr.1991.0407.
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The microindenter has proven to be a powerful device in the characterization of the mechanical properties of thin films. The machine has both high resolution in the applied load and penetration depth measurements, as well as the versatility to perform different types of testing. The former provides the capability to deal with extremely thin films, while the latter allows for other mechanical properties, in addition to hardness, to be acquired. Four types of tests, namely indentation, scratch, load relaxation, and indentation fatigue tests can currently be conducted using the microindenter via different operating procedures. Only the scratch and load relaxation techniques will be covered in this paper. In a microscratch test, the normal load, tangential load, scratch length, and acoustic emission are monitored simultaneously during an entire scratch process for the purposes of measuring the critical load and studying the failure mechanisms of the deposited films. The adhesion strength, scratch hardness, fracture toughness, and friction are the mechanical properties which are possible to obtain by using this technique. Results from aluminum, carbon, and zirconia coatings will be discussed. The load relaxation test provides information on the creep properties of the films and results in an empirical constitutive relation between the applied stress and plastic strain rate. The creep properties of DC sputtered Al films will be used as an illustration of this.
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Krasichkov, A. S., E. Mbazumutima, F. Shikama, and E. M. Nifontov. "A Method for Predicting the Main Indicators of Cardiopulmonary Stress Testing for Patients with Chronic Heart Failure." Journal of the Russian Universities. Radioelectronics 23, no. 1 (February 28, 2020): 96–104. http://dx.doi.org/10.32603/1993-8985-2020-23-1-96-104.
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Introduction. Cardiopulmonary stress test provides significant diagnostic and prognostic information of the condition of patients with cardiovascular and pulmonary diseases. There is a serious problem, that final phase of stress testing is a physically difficult exercise for a person. There is a significant risk of occurrence and development of pathological conditions of the patient's cardiovascular system. One of the solutions is the development of methods for assessing the biological parameters of the patients at the end of a load protocol based on data from the initial stages of the test.Aim. Development of a method for finding an estimate of the maximum heart rate (HR) and of the peak oxygen consumption (OC) for the patients with chronic heart failure at the end of a cardiorespiratory exercise stress test, based on the results of the study obtained at the first initial stages of the test.Materials and methods. For the study, 149 anonymized records of rhythmograms and data of changes in the oxygen consumption of the patients with chronic heart failure were used. The patients underwent a cardiopulmonary stress test by a bicycle ergometer using step-by-step load protocol (the load power increase at each stage was 10 W, the duration of the load stage was 1 min)Results. Based on the analysis of the data obtained, a method for assessing the peak values of HR and of PC of the patients with chronic heart failure was developed.Conclusion. The relative error of the proposed estimate of the HR peak in most cases was no more than 10 %, which allows it to be used for practical purposes. It was established that when performing 70 % of the stress protocol, the error of the proposed estimate of the OC peak in most cases did not exceed 20 %. More research is needed to improve the accuracy of the assessment for using in medical applications aimed to the modernization of methods and equipment for stress testing of the patients.
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Huang, Ledeng, Ruishi Wang, Zhenhua Yang, and Longhan Xie. "Energy Harvesting Backpacks for Human Load Carriage: Modelling and Performance Evaluation." Electronics 9, no. 7 (June 28, 2020): 1061. http://dx.doi.org/10.3390/electronics9071061.
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In recent years, there has been an increasing demand for portable power sources as people are required to carry more equipment for occupational, military, or recreational purposes. The energy harvesting backpack that moves relative to the human body, could capture kinetic energy from human walking and convert vertical oscillation into the rotational motion of the generators to generate electricity. In our previous work, a light-weight tube-like energy harvester (TL harvester) and a traditional frequency-tuneable backpack-based energy harvester (FT harvester) were proposed. In this paper, we discuss the power generation performance of the two types of energy harvesters and the energy performance of human loaded walking, while carrying energy harvesting backpacks, based on two different spring-mass-damper models. Testing revealed that the electrical power in the experiments showed similar trends to the simulation results, but the calculated electrical power and the net metabolic power were higher than that of the experiments. Moreover, the total cost of harvesting (TCOH), defined as additional metabolic power in watt required to generate 1 W of electrical power, could be negative, which indicated that there is a chance to generate 6.11 W of electricity without increasing the metabolic cost while carrying energy harvesting backpacks.
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Shrih, Ali, Adeeb Rahman, and Mustafa Mahamid. "Finite element analysis of tension-loaded ASTM A325 bolts under simulated fire loading." Journal of Structural Fire Engineering 9, no. 1 (March 12, 2018): 2–18. http://dx.doi.org/10.1108/jsfe-06-2016-0006.
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Purpose Nuts and bolts have been used as fasteners of steel structures for many years. However, these structures remain susceptible to fire damage. While conducting fire experiments on steel structures is sometimes necessary, to better understand their behavior, such experiments remain costly and require specialized equipment and testing facilities. This paper aims to present a highly accurate three-dimensional (3D) finite element (FE) model of ASTM A325 bolt subjected to tension loading under simulated fire conditions. The FE model is compared to the results of experimental testing for verification purposes and is proven to predict the response of similar bolts up to certain temperatures without the need for repeated testing. Design/methodology/approach A parametric 3D FE model simulating tested specimens was constructed in the ANSYS Workbench environment. The model included the intricate details of the bolt and nut threads, as well as all the other components of the specimens. A pretension load, a tension force and a heat profile were applied to the model, and a nonlinear analysis was performed to simulate the experiments. Findings The results of the FE model were in good agreement with the experimental results, deviations of results between experimental and FE results were within acceptable range. This should allow studying the behavior of structural bolts without the need for expensive testing. Originality/value Detailed 3D FE models have been created by the authors have been created to study the behavior of structural bolts and compared with experiments conducted by the authors.
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McLoughlin, P., P. Popham, R. A. Linton, R. C. Bruce, and D. M. Band. "Use of arterialized venous blood sampling during incremental exercise tests." Journal of Applied Physiology 73, no. 3 (September 1, 1992): 937–40. http://dx.doi.org/10.1152/jappl.1992.73.3.937.
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Close agreement between arterialized venous and arterial pH, PCO2, and lactate has previously been demonstrated during steady-state exercise. The purpose of the present study was to compare arterialized venous and arterial pH, PCO2, K+, lactate, pyruvate, and epinephrine during the constantly changing circumstances of an incremental exercise test. Eight normal subjects undertook an incremental exercise test (increasing by 20 W/min) to exhaustion on a cycle ergometer during which simultaneous arterial and arterialized venous samples were drawn over the last 20 s of each work load. Linear regression of arterialized venous on arterial values showed that r varied from 0.97 to 0.99 for the variables examined and, therefore, showed that accurate estimates of arterial values could be made from the arterialized venous results during incremental testing. For many purposes it could be assumed that arterialized venous values equaled arterial values without serious error.
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Fedorovsky, Oleksandr, Anna Khizhnyak, Olha Tomchenko, Anatolii Porushkevych, and Ludmyla Pidgorodetska. "Methods for evaluating the ecological condition of freshwater objects based on space geomonitoring and statistical criteria with virtual standards (rationale and testing)." Ukrainian journal of remote sensing, no. 27 (December 10, 2020): 18–25. http://dx.doi.org/10.36023/ujrs.2020.27.174.
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В статье обосновывается предложений способ оценки экологического состояния пресноводных водоемов на основе космического геомониторинга и статистического критерия одновременно по нескольким эталонам, каждый из которых представляет соответствующий уровень техногенного или антропогенной нагрузки. Для этого по каждому изучаемому объекту (водоему) вычисляют вероятности соответствия их информативных признаков информативным признакам каждого эталона. В результате получают количественную оценку влияния нагрузки в относительных единицах или баллах. Приведены примеры апробации предложенного метода для исследования изменения экологического состояния водоемов на примере Киевского водохранилища и озера Свитязь.Для обоснования предложенного способа было определено соответствие полученных результатов на основе статистического критерия оценкам реальной рекреационной нагрузки и оценкам влияния нагрузок полученных методами МКО и МАИ. Для этого были подсчитаны коэффициенты корреляции между этими результатами за соответствующие годы, который в среднем был ровен 0,8, что вполне приемлемо для практических оценок результатов нагрузки на экосистему водоемов. Установлено, что водные объекты представляют собой сложные системы, анализ которых происходит на разных уровнях абстрактного описания с учетом взаимосвязи их составляющих: ландшафтных комплексов (ПТК или биотопов), гидрологических, гидробиологических и гидрохимических характеристик. В ходе исследования выяснено что рекреационная нагрузка на озеро Свитязь постоянно растет и соответственно негативно влияет на его экологическое состояние. Также выявлено, что зарастание акватории верховья Киевского водохранилища высшей водной растительностью также увеличивается, что в свою очередь ослабляет эффективность водохранилища для нужд водопотребления.
The article substantiates the method of assessing the ecological status of freshwater reservoirs using space geomonitoring and statistical criteria with several standards simultaneously, each of which represents the level of technogenic or anthropogenic load. To achieve this, the probabilities of the affiliation of their informative features to the informative features of each standard are calculated for each studied object (reservoir). The result is a quantitative estimation of the load, which is given in relative units or points. The approbation of the offered method for research of the changes in ecological conditions of reservoirs is done over the Kyiv Reservoir and lake Svityaz.During the study of the method, the correspondence of the obtained results using the statistical criterion to the real estimates of recreational load made by the method of multi-criteria optimization (MCO) and method of analysis of hierarchies (MAH) was determined. For this purpose, the correlation coefficient between the obtained result and recreational load, as well as the results of assessments based on MKO and MAH for the respective years was calculated, which averaged 0.8, which is quite acceptable for practical assessments of water ecosystem load. It was determined that water bodies are complex systems and their analysis takes place at different levels of abstractions, taking into account the relationship of their components: landscape complexes (LC), hydrological, hydrobiological and hydrochemical characteristics. The study found that the recreational load on Lake Svityaz is constantly increasing and has negative impact on its ecological condition. It was also found that the overgrowing of the upper springhead of the Kyiv Reservoir with higher aquatic vegetation is also currently increasing, which weakens the efficiency of the reservoir for purposes of water consumption.
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GIS, Wojciech, Jacek PIELECHA, Jerzy MERKISZ, Stanisław KRUCZYŃSKI, and Maciej GIS. "Determining the route for the purpose light vehicles testing in Real Driving Emissions (RDE) test." Combustion Engines 178, no. 3 (July 1, 2019): 61–66. http://dx.doi.org/10.19206/ce-2019-311.
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In the regulations concerning approval of light vehicles starting from September 2019 it will be necessary to conduct exhaust emis-sions tests both on a chassis dynamometer and for real driving emissions. It is a legislative requirement set forth in EU regulations for the purpose of the RDE (Real Driving Emissions) procedure. To decide on the RDE route for the purpose of the LV exhaust emissions tests many requirements must be fulfilled, regarding for ex-ample external temperature and the topographic height of the tests, driving style (driving dynamic parameters), trip duration, length of respective test sections (urban, rural, motorway, etc.). The works on outlining RDE routes are continued across the country in various research centres. Specifying the RDE route for test purposes, i.e. works in which the authors of this article are actively involved, has become a major challenge for future approval surveys concerning the assessment of hazardous emissions from light vehicles and for development studies focusing on – for example – the consumption of energy in electric and hybrid vehicles. The vehicle load was consistent with the requirements of the standard and included the aforesaid measurement device, the driver and the operator of PEMS. The tests were carried out on working days. The streets and roads used for the tests were hard-surfaced. Meas-urements were performed in accordance with the requirements of RDE packages (Package 1–4), i.e. taking into account – among others the engine cold start. The article discusses the method of outlining the test route fulfilling the specific requirements for RDE testing. Chosen results of ex-haust emissions from a passenger car with a spark-ignition engine along the defined RDE test route have been provided. The tests discussed in the article are introductory in the area of RDE tests and provide an introduction into further studies of exhaust emissions and energy consumption in real driving conditions in conventional vehicles and vehicles with alternative engines, e.g. hybrid and electric vehicles.
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Drdlová, Martina, Oldřich Sviták, and Vladan Prachař. "Slurry Infiltrated Fibre Concrete with Waste Steel Fibres from Tires - The Behaviour under Static and Dynamic Load." Materials Science Forum 908 (October 2017): 76–82. http://dx.doi.org/10.4028/www.scientific.net/msf.908.76.
Full textAbstract:
Waste fibres coming from the recycling process of the old tires were incorporated in slurry infiltrated fibre concrete (SIFCON), which is a special type of high performance fibre reinforced concrete with high fibre content. The technological feasibility (i.e. suitability of the waste fibres for SIFCON technology) was assessed using infiltration test and homogeneity test. Test specimens were prepared with three volume fractions (5; 7.5 and 10% by vol.) of waste unclassified fibres. SIFCON with industrial steel fibres (10% by vol.) and high performance fibre concrete with industrial fibres were also cast and tested for comparison purposes. Quasi-static mechanical properties were determined. The impact test was carried out by using an in-house manufactured impact testing machine based on drop test principle. Realized tests confirmed the possibility of using the waste fibres for SIFCON technology. The obtained results indicate, that the usage of waste fibres does not significantly reduce the values of SIFCON flexural and compressive strength at quasi-static load and energy absorption at dynamic load, the values were comparable to the specimens with industrially produced fibres. With increasing fibre content, the mechanical parameters and energy-absorption characteristics at dynamic load are increasing as well.
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Al-Suleiman, Turki I., Mohammed Taleb Obaidat, Ghassan T. Abdul-Jabbar, and Taisir S. Khedaywi. "Field inspection and laboratory testing of highway pavement rutting." Canadian Journal of Civil Engineering 27, no. 6 (December 1, 2000): 1109–19. http://dx.doi.org/10.1139/l00-037.
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The main objective of this research was to investigate the contribution of pavement characteristics, traffic, and physical and mechanical properties of asphaltic mixtures to highway pavement rutting. A total of 51 pavement sections from the rural highway network in Jordan were selected for a case study. The average rut depths for these sections were measured and three cores were drilled for comprehensive laboratory testing. The investigation was performed using four approaches. The first approach considered pavement characteristics represented by surface thickness, last overlay thickness, pavement age, and subgrade California bearing ratio. The average annual equivalent single axle load was also included in this approach. The second approach included Marshall test parameters such as stability, flow, stiffness, and Marshall modulus. The third approach dealt with the effect of mixture air voids on rutting. The variables examined in this approach include air void content within the ruts, voids between ruts, voids near the pavement centerline, and the difference between centerline and rut voids. The fourth approach considered the dynamic permanent deformation characteristics of the pavement surface layer represented by the dynamic modulus. Regression analysis techniques were employed to develop statistical relationships between average rut depths and the parameters examined in each individual approach. The combined effect of these significant parameters on pavement rutting was also examined for prediction purposes. Rutting formation was found to be most dependent on the traffic loading, dynamic modulus of the bituminous mixture and its susceptibility to further compaction, and foundation soil strength.Key words: pavement rutting and characteristics, Marshall test, traffic loading, air voids, static creep, dynamic permanent deformation.
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Wei, Li, Han, Han, Wang, Zhang, and Chen. "Experimental Research on Deformation Characteristics of Using Silty Clay Modified Oil Shale Ash and Fly Ash as the Subgrade Material after Freeze-Thaw Cycles." Sustainability 11, no. 18 (September 19, 2019): 5141. http://dx.doi.org/10.3390/su11185141.
Full textAbstract:
To achieve the purposes of disposing industry solid wastes and enhancing the sustainability of subgrade life-cycle service performance in seasonally frozen regions compared to previous research of modified silty clay (MSC) composed of oil shale ash (OSA), fly ash (FA), and silty clay (SC), we identified for the first time the axial deformation characteristics of MSC with different levels of cycle load number, dynamic stress ratio, confining pressure, loading frequency, and F-T cycles; and corresponding to the above conditions, the normalized and logarithmic models on the plastic cumulative strain prediction of MSC are established. For the effect of cycle load number, results show that the cumulative plastic strain of MSC after 1, 10, and 100 cycle loads occupies for 28.72%~35.31%, 49.86%~55.59%, and 70.87%~78.39% of those after 8000 cycle loads, indicating that MSC possesses remarkable plastic stability after 100 cycles of cycle loads. For the effect of dynamic stress ratio, confining pressure, loading frequency, and F-T cycles, results show that dynamic stress ratio and F-T cycles are important factors affecting the axial deformation of MSC after repeated cycle loads; and under the low dynamic stress ratio, increasing confining pressure and loading frequency have insignificant effect on the axial strain of MSC after 8000 loads. In term of the normalized and logarithmic models on the plastic cumulative strain prediction of MSC, they have a high correlation coefficient with testing data, and according to the above models, the predicted result shows that the cumulative plastic strain of MSC ranges from 0.38 cm to 2.71 cm, and these predicted values are within the requirements in the related standards of highway subgrades and railway, indicating that the cumulative plastic strain of MSC is small and MSC is suitable to be used as the subgrade materials.
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Williams, Tyler D., Michael R. Esco, Michael V. Fedewa, and Phillip A. Bishop. "Inter- and Intra-Day Comparisons of Smartphone-Derived Heart Rate Variability across Resistance Training Overload and Taper Microcycles." International Journal of Environmental Research and Public Health 18, no. 1 (December 29, 2020): 177. http://dx.doi.org/10.3390/ijerph18010177.
Full textAbstract:
The purposes of this study were: (1) to determine if smartphone-derived heart rate variability (HRV) could detect changes in training load during an overload microcycle and taper, and (2) to determine the reliability of HRV measured in the morning and measured immediately prior to the testing session. Twelve powerlifters (male = 10, female = 2) completed a 3-week resistance training program consisting of an introduction microcycle, overload microcycle, and taper. Using a validated smartphone application, daily measures of resting, ultra-short natural logarithm of root mean square of successive differences were recorded in the morning (LnRMSSDM) and immediately before the test session (LnRMSSDT) following baseline, post-overload, and post-taper testing. LnRMSSDM decreased from baseline (82.9 ± 13.0) to post-overload (75.0 ± 9.9, p = 0.019), while post-taper LnRMSSDM (81.9 ± 7.1) was not different from post-overload (p = 0.056) or baseline (p = 0.998). No differences in LnRMSSDT (p < 0.05) were observed between baseline (78.3 ± 9.0), post-overload (74.4 ± 10.2), and post-taper (78.3 ± 8.0). LnRMSSDM and LnRMSSDT were strongly correlated at baseline (ICC = 0.71, p < 0.001) and post-overload (ICC = 0.65, p = 0.010), whereas there was no relationship at post-taper (ICC = 0.44, p = 0.054). Bland–Altman analyses suggest extremely wide limits of agreement (Bias ± 1.96 SD) between LnRMSSDM and LnRMSSDT at baseline (4.7 ± 15.2), post-overload (0.5 ± 16.9), and post-taper (3.7 ± 15.3). Smartphone-derived HRV, recorded upon waking, was sensitive to resistance training loads across an overload and taper microcycles in competitive strength athletes, whereas the HRV was taken immediately prior to the testing session was not.
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Jeppesen, Tina D., Karen L. Madsen, Nanna S. Poulsen, Nicoline Løkken, and John Vissing. "Exercise Testing, Physical Training and Fatigue in Patients with Mitochondrial Myopathy Related to mtDNA Mutations." Journal of Clinical Medicine 10, no. 8 (April 20, 2021): 1796. http://dx.doi.org/10.3390/jcm10081796.
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Mutations in mitochondrial DNA (mtDNA) cause disruption of the oxidative phosphorylation chain and impair energy production in cells throughout the human body. Primary mitochondrial disorders due to mtDNA mutations can present with symptoms from adult-onset mono-organ affection to death in infancy due to multi-organ involvement. The heterogeneous phenotypes that patients with a mutation of mtDNA can present with are thought, at least to some extent, to be a result of differences in mtDNA mutation load among patients and even among tissues in the individual. The most common symptom in patients with mitochondrial myopathy (MM) is exercise intolerance. Since mitochondrial function can be assessed directly in skeletal muscle, exercise studies can be used to elucidate the physiological consequences of defective mitochondria due to mtDNA mutations. Moreover, exercise tests have been developed for diagnostic purposes for mitochondrial myopathy. In this review, we present the rationale for exercise testing of patients with MM due to mutations in mtDNA, evaluate the diagnostic yield of exercise tests for MM and touch upon how exercise tests can be used as tools for follow-up to assess disease course or effects of treatment interventions.
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Bangun, Rahmat Tampune, and Hasanul Fahmi. "Perancangan Sistem Perangkap Hama Tanaman Petani Otomatis Menggunakan Modul Mikrokontroler Arduino." Jurnal Nasional Komputasi dan Teknologi Informasi (JNKTI) 4, no. 1 (February 14, 2021): 26–31. http://dx.doi.org/10.32672/jnkti.v4i1.2663.
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An animal can also be called a pest if it causes damage to natural ecosystems or acts as an agent for spreading disease in human habitats. The pest in question is a mouse-like animal that aims to make a trap using a load cell weight sensor with an Arduino microcontroller module. The scope of the problem in this research is the cultivation of maize and paddy fields in Mardingding District, Karo Regency. For testing purposes, 3 trials are used, respectively, corn and rice fields. The variable is limited to animals the size of a mouse. The purpose of this research is to build a plant pest trapping device using the Arduino uno micro controller module which can make it easier to catch pests efficiently. Farmers no longer need to control within a certain period of time. so it can save time and energy to do other jobs. The application is built using the programming language used is the C language and the Arduino IDE with notification to farmers only via short messages via cellphones.
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Rokonuzzaman, Md, Mohammad Shakeri, Fazrena Azlee Hamid, Mahmuda Khatun Mishu, Jagadeesh Pasupuleti, Kazi Sajedur Rahman, Sieh Kiong Tiong, and Nowshad Amin. "IoT-Enabled High Efficiency Smart Solar Charge Controller with Maximum Power Point Tracking—Design, Hardware Implementation and Performance Testing." Electronics 9, no. 8 (August 7, 2020): 1267. http://dx.doi.org/10.3390/electronics9081267.
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Amid growing demand for solar photovoltaic (PV) energy, the output from PV panels/cells fails to deliver maximum power to the load, due to the intermittency of ambient conditions. Therefore, utilizing maximum power point tracking (MPPT) becomes essential for PV systems. In this paper, a novel internet of things (IoT)-equipped MPPT solar charge controller (SCC) is designed and implemented. The proposed circuit system utilizes IoT-based sensors to send vital data to the cloud for remote monitoring and controlling purposes. The IoT platform helps the system to be monitored remotely. The PIC16F877A is used as a main controller of the proposed MPPT-SCC besides implementing the perturb and observe (P&O) technique and a customized buck–boost converter. To validate the proposed system, both simulation and hardware implementation are carried out by the MATLAB/SIMULINK environment and laboratory set up, respectively. The proposed MPPT-SCC can handle the maximum current of 10 A at 12 V voltage. Results show that the efficiency of the proposed system reaches up to 99.74% during a month of performance testing duration.
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Keipert, N., D. Weaver, R. Summers, M. Clarke, and S. Neville. "Guiding BMP adoption to improve water quality in various estuarine ecosystems in Western Australia." Water Science and Technology 57, no. 11 (June 1, 2008): 1749–56. http://dx.doi.org/10.2166/wst.2008.276.
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The Australian Government's Coastal Catchment Initiative (CCI) seeks to achieve targeted reductions in nutrient pollution to key coastal water quality hotspots, reducing algal blooms and fish kills. Under the CCI a Water Quality Improvement Plan (WQIP) is being prepared for targeted estuaries (Swan–Canning, near Perth, and the Vasse–Geographe, 140 km south of Perth) to address nutrient pollution issues. A range of projects are developing, testing and implementing agricultural Best Management Practices (BMPs) to reduce excessive loads of nutrients reaching the receiving waters. This work builds on progress-to-date achieved in a similar project in the Peel–Harvey Catchment (70 km south of Perth). It deals with the necessary steps of identifying the applicability of BMPs for nutrient attenuation, developing and promoting BMPs in the context of nutrient use and attenuation on farm and through catchments and estimating the degree to which BMP implementation can protect receiving waters. With a range of BMPs available with varying costs and effectiveness, a Decision Support System (DSS) to guide development of the WQIP and implementation of BMPs to protect receiving waters, is under development. As new information becomes available the DSS will be updated to ensure relevance and accuracy for decision-making and planning purposes. The DSS, calibrated for application in the catchments, will play a critical role in adaptive implementation of the WQIP by assessing the effect of land use change and management interventions on pollutant load generation and by providing a tool to guide priority setting and investment planning to achieve agreed WQIP load targets.
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Dudley-Javoroski, Shauna, Andrew E. Littmann, Masaki Iguchi, and Richard K. Shields. "Doublet stimulation protocol to minimize musculoskeletal stress during paralyzed quadriceps muscle testing." Journal of Applied Physiology 104, no. 6 (June 2008): 1574–82. http://dx.doi.org/10.1152/japplphysiol.00892.2007.
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With long-term electrical stimulation training, paralyzed muscle can serve as an effective load delivery agent for the skeletal system. Muscle adaptations to training, however, will almost certainly outstrip bone adaptations, exposing participants in training protocols to an elevated risk for fracture. Assessing the physiological properties of the chronically paralyzed quadriceps may transmit unacceptably high shear forces to the osteoporotic distal femur. We devised a two-pulse doublet strategy to measure quadriceps physiological properties while minimizing the peak muscle force. The purposes of the study were 1) to determine the repeatability of the doublet stimulation protocol, and 2) to compare this protocol among individuals with and without spinal cord injury (SCI). Eight individuals with SCI and four individuals without SCI underwent testing. The doublet force-frequency relationship shifted to the left after SCI, likely reflecting enhancements in the twitch-to-tetanus ratio known to exist in paralyzed muscle. Posttetanic potentiation occurred to a greater degree in subjects with SCI (20%) than in non-SCI subjects (7%). Potentiation of contractile rate occurred in both subject groups (14% and 23% for SCI and non-SCI, respectively). Normalized contractile speed (rate of force rise, rate of force fall) reflected well-known adaptations of paralyzed muscle toward a fast fatigable muscle. The doublet stimulation strategy provided repeatable and sensitive measurements of muscle force and speed properties that revealed meaningful differences between subjects with and without SCI. Doublet stimulation may offer a unique way to test muscle physiological parameters of the quadriceps in subjects with uncertain musculoskeletal integrity.
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Mironov, Vladimir I., Olga A. Lukashuk, and Ivan S. Kamantsev. "Experimental Study of Strain-Softening Stage in Materials." Materials Science Forum 946 (February 2019): 276–81. http://dx.doi.org/10.4028/www.scientific.net/msf.946.276.
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Physical theory of reliability is based on research into degradation processes of various origins which take place in a material of a stressed construction. Experimental evaluation of parameters carried out for such processes is a practically important problem by itself. One of the approaches to solving this problem is related to the studies into the stage of material softening due to deformation. This paper analyzes the issues of experimental validation of material softening properties in terms of a phenomenological approach to the problem of structural fracture. Results of deformation analysis for the “machine – model specimen” system, using catastrophe theory are used to form requirements for carrying out experiments which investigate the softening stage of materials. The success of such experiments – which should include recording a branch descending to zero on a computer diagram – is possible when small specimen, made from structurally heterogeneous materials, are strained in a sufficiently rigid testing machine. Thus, the conditions for manifestation of the softening stage connect properties of the material with properties of the load-applying system. Therefore, the material's limiting state – preceding the fractured – also depends on the conditions of loading, and the criteria of that fracture would be nonlocal. In consideration of the results of diagrams plotted from various bases for deformation measurement, a necessity of utilizing local material characteristics for calculation purposes is discussed. As an example of using the complete diagrams for determining kinetics of material degradation from external load, the results of specimen testing, which follows a cyclic training, are cited.
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Keser, Reyhan Kevser, Esra Ergün, and Behçet Uğur Töreyin. "Vehicle Logo Recognition with Reduced-Dimension SIFT Vectors Using Autoencoders." Proceedings 2, no. 2 (January 9, 2018): 92. http://dx.doi.org/10.3390/proceedings2020092.
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Vehicle logo recognition has become an important part of object recognition in recent years because of its usage in surveillance applications. In order to achieve a higher recognition rates, several methods are proposed, such as Scale Invariant Feature Transform (SIFT), convolutional neural networks, bag-of-words and their variations. A fast logo recognition method based on reduced-dimension SIFT vectors using autoencoders is proposed in this paper. Computational load is decreased by applying dimensionality reduction to SIFT feature vectors. Feature vectors of size 128 are reduced to 64 and 32 by employing two layer neural nets called vanilla autoencoders. Publicly available vehicle logo images are used for testing purposes. Results suggest that the proposed method needs half of the original SIFT based method’s memory requirement with decreased processing time per image in return of a decrease in the accuracy less than 20%.
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Khaleghian, Seyedmeysam, Omid Ghasemalizadeh, and Saied Taheri. "Estimation of the Tire Contact Patch Length and Normal Load Using Intelligent Tires and Its Application in Small Ground Robot to Estimate the Tire-Road Friction." Tire Science and Technology 44, no. 4 (October 1, 2016): 248–61. http://dx.doi.org/10.2346/tire.16.440402.
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ABSTRACT Tire-road friction estimation is one of the most popular problems for the tire and vehicle industry. Accurate estimation of the tire-road friction leads to better performance of the traction and antilock braking system controllers, which reduces the number of accidents. Several researchers have worked in the field of friction estimation, and many tire models have been developed to predict the tire-road friction. In this article, an intelligent tire, which has an embedded accelerometer placed on the inner liner of the tire, is used to estimate the tire contact patch length parameter and normal load. To accomplish this, first, an existing tire testing trailer equipped with a force hub to measure tire forces and moments, a high-accuracy encoder to measure the angular velocity of the wheel, and VBOX, which is a global positioning system–based device, to estimate the longitudinal speed of the trailer was used. As a practical application for the normal load algorithm, a wheeled ground robot, which is equipped with several sensors, including an accelerometer and a flexible strain sensor inside the tire (used for terrain identification purposes), was designed and built. A set of algorithms was developed and used with the test data that were collected with both the trailer and the robot, and the contact patch length and the normal load were estimated. Also, the friction potential between the tire and the road was evaluated using a small ground robot.
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Suhir, E. "Could Shock Tests Adequately Mimic Drop Test Conditions?" Journal of Electronic Packaging 124, no. 3 (July 26, 2002): 170–77. http://dx.doi.org/10.1115/1.1487356.
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Drop tests are often substituted in qualification or life testing of microelectronic and optoelectronic products by shock tests. The existing (e.g., Telcordia) qualification specifications require that a short term load of the given magnitude and duration (say, an “external” acceleration with the maximum value of 500 g, acting for 0.001 s) is applied to the support structure of the product under test. The natural frequencies of vibration are not taken into account. The objective of our study is to develop simple analytical (“mathematical”) predictive models for the evaluation of the dynamic response of a structural element in a microelectronic or an optoelectronic product/package to an impact load occurring as a result of drop or shock tests. We use the developed models to find out if a shock tester could be “tuned” in such a way that the shock tests adequately mimic drop test conditions. We suggest that the maximum induced curvature and the maximum induced acceleration be used as suitable characteristics of the dynamic response of a structural element to an impact load. Indeed, the maximum curvatures determine the level of the bending stresses, and the maximum accelerations are supposedly responsible for the functional (electronic or photonic) performance of the product. We use the case of an elongated rectangular simply supported plate as an illustration of the suggested concept. We show that in order to adequately mimic drop test conditions, the shock test loading should be as close as possible to an instantaneous impulse, and that the duration of the shock load should be established based on the lowest (fundamental) natural frequency of vibrations. We show also that, for practical purposes, it is sufficient to consider the fundamental mode of vibrations only, and that the shock load does not have to be shorter than, say, half the quarter of the fundamental period. We demonstrate that, if the loading is not short enough, the induced curvatures and accelerations can exceed significantly the curvatures and accelerations in drop test conditions. Certainly, the results of such shock tests will be misleading. After the appropriate duration of the shock impulse is established, the time dependence and the maximum value of the imposed (“external”) acceleration in shock tests should be determined, depending on the most likely drop height, in order to adequately mimic drop test conditions. We demonstrate that the application of a probabilistic approach can be helpful in understanding the mechanical behavior and to ensure high short- and long-term reliability of an electronic or photonic device that might be or will be subjected to an accidental or expected impact loading. We conclude that although it is possible to “tune” the shock tester, so that the drop test conditions are adequately reproduced, actual drop tests should be conducted, whenever possible. The results of the analysis can be helpful in physical design and qualification testing of microelectronic and photonic products, experiencing dynamic loads of short duration.
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Lee, Kwang-Myong, Young-Cheol Choi, Byoungsun Park, Jinkyo Choo, and Sung-Won Yoo. "Effect of Clinker Binder and Aggregates on Autogenous Healing in Post-Crack Flexural Behavior of Concrete Members." Materials 13, no. 20 (October 12, 2020): 4516. http://dx.doi.org/10.3390/ma13204516.
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Crack healing has been studied extensively to protect reinforced concrete structures from the ingress of harmful ions. Research examining the regain in the mechanical properties of self-healing composites has focused mostly on the computation of the healing ratio based on the measurement of the tensile and compressive strengths but with poor regard for the flexural performance. However, the regain in the flexural performance should also be investigated for design purposes. The present study performs flexural testing on reinforced concrete members using crushed clinker binder and aggregates as well as crystalline admixtures as healing agents. Healing ratios of 100% for crack widths smaller than 200 μm and 85% to 90% for crack widths of 250 μm were observed according to the admixing of clinker binder and aggregates. Water flow test showed that the members replacing binder by 100% of clinker achieved the best crack healing performance. The crack healing property of concrete improved to some extent the rebar yield load, the members’ ultimate load and energy absorption capacity and ductility index. The crack distribution density from the observed crack patterns confirmed the crack healing effect provided by clinker powder. The fine grain size of clinker made it possible to replace fine aggregates and longer healing time increased the crack healing effect.
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Camporeale, S. M., B. Fortunato, and M. Mastrovito. "A Modular Code for Real Time Dynamic Simulation of Gas Turbines in Simulink." Journal of Engineering for Gas Turbines and Power 128, no. 3 (March 1, 2002): 506–17. http://dx.doi.org/10.1115/1.2132383.
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A high-fidelity real-time simulation code based on a lumped, nonlinear representation of gas turbine components is presented. The code is a general-purpose simulation software environment useful for setting up and testing control equipments. The mathematical model and the numerical procedure are specially developed in order to efficiently solve the set of algebraic and ordinary differential equations that describe the dynamic behavior of gas turbine engines. For high-fidelity purposes, the mathematical model takes into account the actual composition of the working gases and the variation of the specific heats with the temperature, including a stage-by-stage model of the air-cooled expansion. The paper presents the model and the adopted solver procedure. The code, developed in Matlab-Simulink using an object-oriented approach, is flexible and can be easily adapted to any kind of plant configuration. Simulation tests of the transients after load rejection have been carried out for a single-shaft heavy-duty gas turbine and a double-shaft aero-derivative industrial engine. Time plots of the main variables that describe the gas turbine dynamic behavior are shown and the results regarding the computational time per time step are discussed.
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Bucur, Florina, Adrian Rotariu, Liviu Matache, Florin Baciu, Gabriel Jiga, and Eugen Trana. "Experimental and Numerical Study on the Behavior of Dyneema� HB26 Composite in Compression." Materiale Plastice 57, no. 2 (July 1, 2019): 113–22. http://dx.doi.org/10.37358/mp.20.2.5357.
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In the last decades as the need for high economical and technical efficiency items/applications became acute, lightweight, high strength and low-cost materials development and investigation emerged as a logical and promising course of action. With high potential for both military and civil sector, the ultra-high molecular weight polyethylene (UHMWPE) is considered a new class of material. Among this class, the Dyneema� HB26 composite is of most interest for the present study. The present paper focuses on the static and dynamic investigation of the HB26 mechanical behavior experiencing an out of plane compressive load. For experimental purposes, using a 15 mm thickness panel two types of samples (cylindrical and cubic samples) were processed. For compression test Instron Testing Machine and the Split Hopkinson Pressure Bar (SHPB) were used. The experimental tests were then compared against the numerical findings highlighting a good consistency.
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Amoabeng, Lee, and Choi. "Modeling and Simulation Performance Evaluation of a Proposed Calorimeter for Testing a Heat Pump System." Energies 12, no. 23 (December 2, 2019): 4589. http://dx.doi.org/10.3390/en12234589.
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The energy consumption for heating and cooling in the building sector accounts for more than one-third of total energy used worldwide. In view of that, it is important to develop energy efficient cooling and heating systems in order to conserve energy in buildings as well as reduce greenhouse gas emissions. In both commercial and residential buildings, the heat pump has been adopted as an energy efficient technology for space heating and cooling purposes as compared to conventional air conditioning systems. However, heat pumps undergo standard testing, rating, and certification procedures to ascertain their system performance. Essentially, the calorimeter for testing heat pumps has two test chambers to serve as a heat source and heat sink to control and maintain the test conditions required to simulate the heat pump indoor and outdoor units, simultaneously. In air-to-air heat pump units, the conventional calorimeter controls the air temperature and humidity conditions in each test chamber with separate air handling units consisting of a refrigerator, heater, humidifier, and supply fan, which results in high energy consumption. In this study, using dynamic modeling and simulation, a new calorimeter for controlling air conditions in each test chamber is proposed. The performance analysis based on simulation results showed that the newly proposed calorimeter predicted at least 43% energy savings with the use of a heat recovery unit and small refrigerator capacity as compared to the conventional calorimeter that utilized a large refrigerator capacity for all the weather conditions and load capacities that we investigated.
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Drdlová, Martina, Radek Řídký, and René Čechmánek. "Influence of Fibre Type and Fibre Volume Fraction on Dynamic Properties of Slurry Infiltrated Fibre Concrete." Materials Science Forum 865 (August 2016): 135–40. http://dx.doi.org/10.4028/www.scientific.net/msf.865.135.
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The effect of fibre type and fibre amount on physico-mechanical properties of slurry infiltrated fibre concrete (SIFCON) at both quasi-static and dynamic load was evaluated experimentally. SIFCON is a special type of cement-based composite with high fibre volume fraction, extremely strong and ductile. Test specimens were prepared with 7 types of steel fibres (with different shape and mechanical parameters) in four volume fractions (7.5-15 vol. %). High performance fibre-reinforced concrete (HPFRC) has also been cast and tested for comparison purposes. The impact test has been carried out by using an in-house manufactured impact testing machine based on drop test principle. The test results revealed that SIFCON slab with 15 vol. % fibre content exhibits superior energy-absorption characteristics when compared to other slab specimens. Diameter of the fibres plays an important role for both strength and energy absorption capacity of SIFCON - using of low-diameter fibres with higher aspect ratio leads to the best results.
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Zenunović, Damir, and Danijel Ružić. "Comparative analysis of behaviour of reinforced concrete beams using bars and textil: Experimental research." Gradjevinski materijali i konstrukcije 63, no. 4 (2020): 87–98. http://dx.doi.org/10.5937/grmk2004087z.
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This paper presents an experimental program of initial testing of reinforced concrete beams using bars and textiles carried out with an aim of comparative analysis of the behaviour of reinforced concrete beams using textiles in relation to conventional reinforced beams. Alkalineresistant glass fibre textile meshes were used for the purposes of the experiment. An experiment setting is described and obtained test results are presented in this paper. An analysis of the obtained results is presented at the end of the paper. The experimental program demonstrated that adding textile mesh, besides improvement of the durability of the protective layer of concrete, can improve the load-bearing capacity and ductility of reinforced concrete beams. There is still an issue related to workability of concrete in textile reinforced beams and achievement of full adhesion between textile mesh and concrete. At the end of the paper, a suggestion was given about semi-prefabricated reinforced concrete beams using reinforced bars and textiles.
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Kamarposhti, Mehrdad Ahmadi, and Ashkan Abyar Hosseini. "Modified approach for harmonic reduction in three-phase to seven-phase using transformer winding connections." International Journal of Electrical and Computer Engineering (IJECE) 9, no. 3 (June 1, 2019): 1496. http://dx.doi.org/10.11591/ijece.v9i3.pp1496-1505.
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Three phase supply is available in the generating station or grid, were as seven phase supply is required for many industrial applications such as, aerospace, railway and automobile applications. There are different methods in which we can convert 3 to 7 phase using 24-Pulse Converter, Carrier Based PWM Technique, multilevel converter and Multiphase Transformer. The above said methods which are more complicated to design for higher ratings or a pure sine wave will not be obtained or harmonics will be more. For Multiphase power transmission system multiphase transformers are needed. In the multiphase power transmission and multiphase rectifier systems, the number of phase can be designed and developed in multiples of three. Therefore, the variable speed multiphase drive system considered in the literature are mostly of five, seven, nine, eleven, twelve, and fifteen phase. So, there is a need to design and develop special transformer which converts from 3 to 7 phase for different arrangement of input and output. Thus, with the proposed technique, a pure seven-phase sine-wave of fixed voltage/current and frequency is obtained, which can be used for RL load and motor testing purposes. Complete design and simulation of the proposed solution is presented. Analytical calculation and simulation results for RL load is presented in the paper. This model can be simulated by using Orcad simulation software and “SimPowerSystem” block sets of MATLAB/SIMULINK software.
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Rostami, Javad, Peter W. Tse, and Maodan Yuan. "Detection of broken wires in elevator wire ropes with ultrasonic guided waves and tone-burst wavelet." Structural Health Monitoring 19, no. 2 (June 12, 2019): 481–94. http://dx.doi.org/10.1177/1475921719855915.
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Elevator wire ropes with polymer cores hold and hoist heavy fluctuating loads in a corrosive environment. Such working condition causes metal fatigue, which together with abrasion around pulleys leads to progressive loss of the metallic cross section. This can be seen in the forms of a roughened and pitted surface of the ropes, reduction in diameter, and broken wires. Therefore, their deterioration must be monitored so that any unexpected damage or corrosion can be detected before it causes a fatal accident. Ultrasonic-guided wave-based inspection, which has proved its capability in nondestructive testing of platelike structures such as tubes and pipes, can monitor the cross section of wire ropes in their entire length from a single point. However, guided waves have drawn less attention for defect detection purposes in wire ropes. This article reports the condition monitoring of a steel wire rope from a hoisting elevator with broken wires as a result of corrosive environment and fatigue. Finite element analysis was conducted as a baseline to study guided wave propagation in wire ropes and plot dispersion curves. Guided wave propagation in wire ropes was experimentally investigated on a newly built cable stretching machine equipped with a load sensor under different amount of tensile loading. To expose the indication of broken wires, the recorded signals were analyzed by tailor-made continuous wavelet transform called tone burst wavelet.
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Applegate, Brooks. "Construction of Geometric Analogy Problems by Young Children in a Computer-Based Test." Journal of Educational Computing Research 9, no. 1 (February 1993): 61–77. http://dx.doi.org/10.2190/f77b-ppya-v1ex-lwdy.
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The two purposes of this study were a) to explore how young children structure and solve geometric analogy problems in a computer-based test, and b) to compare this performance to the same item stems in a paper-and-pencil form. Twenty-four kindergarten and twenty-four second-grade children were required to construct solutions to analogy problems that were presented on a microcomputer. Half of the sample was academically gifted. These kindergartners were also tested with a paper-and-pencil version of the test to examine for possible differences between the two testing methods. Second graders were only tested with the computer version. Statistical analysis for the computer-based test focused on how these young children constructed responses to geometric analogy problems, and the error patterns committed by each age group. Analyses showed a strong linear decrease in performance as the item information load increased, but this effect was more pronounced for the kindergartners than for the second graders. Analyses also provided some evidence that changing the items from a paper-and-pencil response selection format to a constructed response format alters which component of the item carries the greatest weight in determining overall item performance. This study also investigated the crossover effects of computer-based testing on paper-and-pencil testing and vice versa in the kindergarten subjects. It was found that there was a positive effect on the post-test computer-based performance when pretested with the paper-form, but a negative effect on paper-form post-test performance when pretested with the computer form.
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Adriansyah, Yan, Guruh Krisnantara, and Kurniawan Setiadi. "Korelasi Point Load Index dan Uniaxial Compressive Strength pada Satuan Batupasir dan Batulempung Formasi Latih untuk Penentuan Koefisien Kekuatan Batuan di Pit X Tambang Batubara PT Berau Coal, Kalimantan Timur." Jurnal Geomine 9, no. 1 (August 20, 2021): 9–16. http://dx.doi.org/10.33536/jg.v9i1.822.
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Physical and mechanical properties of rock for engineering purposes are indispensable for any civil/construction, mining and other engineering requirment. The results of the uniaxial compressive strength (UCS) test are very much needed in various geotechnical analyzes or engineering, in particular in the mining industry in relation to the calculation of the pit slope design and other mining infrastructure. Rock samples used in this study were obtained from the results of geotechnical drilling (full core drilling). The rock engineering properties test to obtain UCS and PLI values was carried out in the laboratory. Testing the rock hardness index using the point load index (PLI) can be done more quickly, cheaply, practically and can use rock samples with a variety of sample shapes. The focus and object of the research are mudstone and sandstone units as part of the Lati Formation. These two types of layers are the most dominant rock types as a constituent of the pit slopes in the research area. To ensure that the correlation results are in accordance with the rules of scientific research, the distribution of UCS and PLI data from laboratory test results is verified using a statistical approach / testing. Correlation and analysis between the two rock engineering properties test results are very useful for geotechnical analysis data input. The coefficient or constant values obtained can be used to determine the rock strength values used in various geotechnical analyzes so that the analysis can be carried out more efficiently, effectively and quickly and can support geotechnical engineering work.
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Fiedler, Goeran, and Krista Kutina. "Feasibility of a mobile feedback system for gait retraining in people with lower limb loss—A technical note." Journal of Rehabilitation and Assistive Technologies Engineering 6 (January 2019): 205566831881368. http://dx.doi.org/10.1177/2055668318813682.
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Gait retraining in people with musculoskeletal and/or neurological impairments requires sustained dedicated efforts by the patient and the rehabilitation therapist. Various technical approaches have been proposed and utilized to improve the effectiveness of training interventions. Among the most promising approaches is the provision of real-time feedback information to the patient, which has been used with success on treadmill-based interventions in the past. We are describing a mobile visual feedback system that is intended to work in the user’s everyday-life environment. The data are captured by a small mobile load cell, processed in a wearable computer, and displayed to the user via smart-glasses. Preliminary testing of the initially selected feedback variable stance/step ratio (i.e., the duration of a step’s stance phase in relation to the overall step’s duration) confirmed that data quality is sufficient for purposes of generating feedback information and that the chosen variable is responsive to changes in gait symmetry. The presented work may inform future studies and developments on the topic of mobile visual feedback for gait rehabilitation.
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Campagnolo, Alberto, Manuele Dabalà, and Giovanni Meneghetti. "Effect of Salt Bath Nitrocarburizing and Post-Oxidation on Static and Fatigue Behaviours of a Construction Steel." Metals 9, no. 12 (December 4, 2019): 1306. http://dx.doi.org/10.3390/met9121306.
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Several surface modification technologies are typically applied to improve the mechanical properties of the material surface of structural components subjected to severe conditions of load, wear and chemical erosion of the surface. The nitrocarburizing and post-oxidation heat treatment, also known as quench-polish-quench (QPQ), improves the fatigue, wear and corrosion resistance properties of the material, since it increases the surface hardness and generates surface compressive residual stresses. In the present contribution, the effects of the salt bath nitrocarburizing and post-oxidation heat treatment on the static and fatigue behaviours of 39NiCrMo3 construction steel have been investigated by experimentally testing plain as well as notched specimens. For comparison purposes, 39NiCrMo3 construction steel, both untreated and treated, and X5CrNiCuNb 16-4 stainless steel have been tested. First, the microstructure of the untreated and treated steel has been identified by metallographic analysis; micro-hardness measurements have been collected and residual stresses profiles have been obtained by using the X-ray diffraction technique. Then, experimental static and fatigue tests have been performed. Finally, the fracture surfaces have been analysed to locate fatigue crack nucleation sites.
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Godin, Jonathan A., Jorge Chahla, Gilbert Moatshe, Bradley M. Kruckeberg, Kyle J. Muckenhirn, Alexander R. Vap, Andrew G. Geeslin, and Robert F. LaPrade. "A Comprehensive Reanalysis of the Distal Iliotibial Band: Quantitative Anatomy, Radiographic Markers, and Biomechanical Properties." American Journal of Sports Medicine 45, no. 11 (June 13, 2017): 2595–603. http://dx.doi.org/10.1177/0363546517707961.
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Background: The qualitative anatomy of the distal iliotibial band (ITB) has previously been described. However, a comprehensive characterization of the quantitative anatomic, radiographic, and biomechanical properties of the Kaplan fibers of the deep distal ITB has not yet been established. It is paramount to delineate these characteristics to fully understand the distal ITB’s contribution to rotational knee stability. Purpose/Hypothesis: There were 2 distinct purposes for this study: (1) to perform a quantitative anatomic and radiographic evaluation of the distal ITB’s attachment sites and their relationships to pertinent osseous and soft tissue landmarks, and (2) to quantify the biomechanical properties of the deep (Kaplan) fibers of the distal ITB. It was hypothesized that the distal ITB has definable parameters concerning its anatomic attachments and consistent relationships to surgically pertinent landmarks with correlating plain radiographic findings. In addition, it was hypothesized that the biomechanical properties of the Kaplan fibers would support their role as important restraints against internal rotation. Study Design: Descriptive laboratory study. Methods: Ten nonpaired, fresh-frozen human cadaveric knees (mean age, 61.1 years; range, 54-65 years) were dissected for anatomic and radiographic purposes. A coordinate measuring device quantified the attachment areas of the distal ITB to the distal femur, patella, and proximal tibia and their relationships to pertinent bony landmarks. A radiographic analysis was performed by inserting pins into the attachment sites of relevant anatomic structures to assess their location relative to pertinent bony landmarks with fluoroscopic guidance. A further biomechanical assessment of 10 cadaveric knees quantified the load to failure and stiffness of the Kaplan fibers’ insertion on the distal femur after a preconditioning protocol. Results: Two separate deep (Kaplan) fiber bundles were identified with attachments to 2 newly identified femoral bony prominences (ridges). The proximal and distal bundles inserted on the distal femur 53.6 mm (95% CI, 50.7-56.6 mm) and 31.4 mm (95% CI, 27.3-35.5 mm) proximal to the lateral epicondyle, respectively. The centers of the bundle insertions were 22.5 mm (95% CI, 19.1-25.9 mm) apart. The total insertion area of the distal ITB on the proximal tibia was 429.1 mm2 (95% CI, 349.2-509.1 mm2). A distinct capsulo-osseous layer of the distal ITB was also identified that was intimately related to the lateral knee capsule. Its origin was in close proximity to the lateral gastrocnemius tubercle, and it inserted on the proximal tibia at the lateral tibial tubercle between the fibular head and the Gerdy tubercle. Radiographic analysis supported the quantitative anatomic findings. The mean maximum load during pull-to-failure testing was 71.3 N (95% CI, 41.2-101.4 N) and 170.2 N (95% CI, 123.6-216.8 N) for the proximal and distal Kaplan bundles, respectively. Conclusion: The most important finding of this study was that 2 distinct deep bundles (Kaplan fibers) of the distal ITB were identified. Each bundle of the deep layer of the ITB was associated with a newly identified distinct bony ridge. Radiographic analysis confirmed the measurements previously recorded and established reproducible landmarks for the newly described structures. Biomechanical testing revealed that the Kaplan fibers had a strong attachment to the distal femur, thereby supporting a role in rotational knee stability. Clinical Relevance: The identification of 2 distinct deep fiber (Kaplan) attachments clarifies the function of the ITB more definitively. The results also support the role of the ITB in rotatory knee stability because of the fibers’ vectors and their identified maximum loads. These findings provide the anatomic and biomechanical foundation needed for the development of reconstruction or repair techniques to anatomically address these deficiencies in knee ligament injuries.
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Arts, J. J. C., B. W. Schreurs, P. Buma, and N. Verdonschot. "Cemented Cup Stability during Lever-Out Testing after Acetabular Bone Impaction Grafting with Bone Graft Substitutes Mixes Containing Morselized Cancellous Bone and Tricalcium Phosphate-Hydroxyapatite Granules." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 219, no. 4 (April 1, 2005): 257–63. http://dx.doi.org/10.1243/095441105x34266.
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Bone defects after failed total hip arthroplasty can be reconstructed with impacted morselized bone grafts and a cemented cup. In the near future the amount of bone grafts available for surgical purposes will be insufficient. Ceramic calcium phosphates [tricalcium phosphate (TCP) and hydroxyapatite (HA)] have been widely considered as potential bone graft substitutes or bone graft extenders. In the past, mechanical experiments have been performed to determine implant stability of bone grafts and ceramic TCP-HA granules mixes under a compressive load. However, in-vivo migration studies suggest that shear loading may be equally important. This in-vitro study investigated the initial stability of cups reconstructed with various mixes of bone grafts and ceramic TCP-HA granules in a lever-out situation, where shearing is the predominant loading mode. It was found that the cups reconstructed with mixes of bone graft and TCP-HA granules exhibited greater mechanical stability than the cups reconstructed with bone grafts only. It is concluded that from a mechanical standpoint, when considering shear force resistance, 50–50 per cent volume mix and 25–75 per cent volume mix of morselized cancellous bone graft and TCP-HA granules both provide adequate initial cup stability and can be used for acetabular reconstructions with the bone impaction grafting technique.