Established Test Methods Research Articles

Machine Learning-Based Prediction Approach for COVID-19 Detection via Chest X-Ray Scans

Objectives: In medical research, the application of AI technologies has become a desirable approach for disease diagnosis due to their ability to increase diagnosis speed and accuracy. One major application of these technologies is in diagnosing diseases using medical imagery data such as X-ray and CT scan images. The objective of this study is to implement a COVID-19 diagnosis approach based on ML and compare it with laboratory testing approaches. Methods: The study utilizes the VGG16 architecture to extract features from X-ray and CT scan images, which are then used to build an ANN classifier to predict images as either COVID-positive or normal. Real-world datasets of varying difficulty were employed to evaluate the system's performance under different stressors, while comparative analysis with other classifiers was conducted to assess the model's improvement in accuracy and time complexity. Findings: The proposed architecture correctly classified 98.41% of the testing images. Among the images from infected patients in the testing set, 97.54% were accurately identified, while 98.72% of the normal cases were correctly classified. The model demonstrated good precision, with 96.49% of predicted COVID cases truly being from COVID-19 patients. Additionally, the F1 score for the model is 98.41%, indicating a good balance in predicting both categories. Showcasing its ability to handle multiple predictions quickly. The model's execution time for classifying a single case was computed as 0.0039 seconds, showcasing its ability to handle multiple predictions quickly. The proposed approach exhibits superior performance on datasets with balanced outcomes, surpassing the accuracy of SVM, DT, Logistic Regression, and Random Forest models. The approach outperforms laboratory-based testing approaches in terms of accuracy cost and assay times. Novelty: This study not only implements a robust ML-based approach for COVID-19 diagnosis but also provides a unique comparative analysis with traditional laboratory-based testing methods, such as Reverse Transcription Polymerase Chain Reaction (RT-PCR), reported in other literature. This dual focus on ML performance and its comparison with established testing methods highlights the practical advantages of ML in terms of diagnosis speed, accuracy, and cost-efficiency, offering a comprehensive perspective not commonly addressed in existing research. Keywords: COVID-19, Machine Learning techniques, F1 score, Classifier, Specificity, Accuracy, Sensitivity, Precision

Investigation and comparison of insulating oil properties using various analytical methods

ABSTRACT In the current scenario, rising energy consumption has put a significant burden on transformers. Simultaneously, power utility companies are reducing their capital investments. As a result, industrial consumers are increasingly focused on maintaining the trouble-free operation of their existing transformers to ensure their reliability remains intact. The reliability of the transformer heavily counts on the health and condition of its insulating oil and the various physicochemical and dielectric properties associated with it. Various national and international organisations, such as ASTM, IEC, and IS (Indian Standard), have established standardised test methods to evaluate the insulating oil properties. These tests help in assessing the oil’s quality and the transformer’s condition. Monitoring the properties of insulating oil using established test methods is vital for assuring transformer reliability. It allows for early detection of potential issues and enables timely maintenance or replacement actions to prevent costly failures. This paper aims to analyse and compare the key properties of mineral insulating oil including breakdown voltage (BDV), water content, IFT, and acidity, utilising ASTM, IEC, and IS standard test methods to assess the accuracy and uniformity of the test method. The results serve as a valuable resource for analysts and professionals.

Biodegradation behavior of wool and other textile fibers in aerobic composting conditions

AbstractPollution of the environment by microscopic fragments of plastic is a growing environmental concern. A category of this pollution is fiber fragments from textiles, a source of which is believed to be fibers released by clothing made of synthetic fibers during laundering. These fragments could enter the environment at the end of the textile’s useful life if it is not re-used or recycled. Disposal of biodegradable fibers could be achieved by industrial composting, but natural fibers are sometimes modified during manufacturing in ways that might influence biodegradation. The composting behavior of fabrics made with unmodified and chemically modified wool fibers (chlorine-Hercosett treated), regenerated cellulose, and several synthetic fibers was compared in industrial composting conditions according to an established standard test method. The fabrics were characterized by Fourier transform infrared spectroscopy, energy dispersive X-ray and electron microscopy. The regenerated cellulose (viscose rayon) biodegraded to the greatest extent in the test, and both types of wool also biodegraded readily. All three synthetic fibers had no biodegradation. The machine-washable wool biodegraded more rapidly than unmodified wool and analysis of residues at the conclusion of the test indicated that it did not generate non-degradable fiber fragments. The epicuticle of unmodified wool is covered with a hydrophobic layer, which may resist microbial attack, but with time this slowly degraded. Conversely, the machine-washable wool is hydrophilic and therefore was easier for microbes to attack. If not re-used, commercial, machine-washable wool textiles can be readily disposed of in industrial composting conditions.

Transient temperature measurement of silicon carbide Schottky barrier diode based on thermal reflection.

In this article, we present a transient temperature detection device for silicon carbide (SiC) Schottky barrier diodes (SBDs) based on thermal reflection theory. We constructed a thermal reflection temperature measurement device based on a 530-nm green laser. This device is more suitable for transient temperature measurement of SiC SBDs than previous thermal reflection equipment. The accuracy of temperature measurement by our device was confirmed by comparison with the results of infrared thermal imaging. The high temporal resolution characteristics of the thermal reflection technology allowed the detection of millisecond-level transient temperature changes in SiC SBDs. In addition, we investigated the complementarity of transient temperature change curves during heating and cooling processes, as well as the reasons for the differences between these curves. Finally, we used the structural function method combined with the Bayesian deconvolution algorithm to obtain the thermal resistance along the heat flow path of the device and validated the results using an established thermal resistance testing method.

Experimental Method to Determine the Draping Behavior of Auxiliary Materials for the Vacuum Bagging of CFRP Parts on Doubled-Curved Surfaces

The production costs of aircraft primary structures made of carbon fibre reinforced polymer (CFRP) are significantly higher than for comparable metal-based structures. Today substantial effort is made to achieve a sufficient reproducibility and parts’ quality in manufacturing processes of CFRP structures. Especially the sub process vacuum bagging for infusion processes is still expensive. One of the reasons is the complex positioning of the flexible auxiliary materials which have to be stacked on the preform. During the positioning on doubled-curved surfaces these materials tend to form wrinkles, which can lead to defects of the composite part. Yet, a defined description of the wrinkling behavior of the auxiliary materials on doubled-curved surfaces does not exist. In this work a characterization of the wrinkling behavior on doubled-curved surfaces is investigated for the auxiliary materials of the Vacuum Assisted infusion Process (VAP®): release film, perforated peel ply, flow media, membrane and vacuum foil. Therefore, an experimental test method is derived similar to established hemisphere deformation test methods. The wrinkling behavior for the specific VAP auxiliary materials is empirically determined on differently curved surface geometries. It is shown that the draping behavior can be characterized by partial wrinkle-free surfaces between the wrinkles. A material specific threshold is derived to determine the appearance of wrinkles. The work shows that a characterization of the draping behavior of auxiliary materials on doubled-curved surfaces is possible. With the gained knowledge the potential for an increase of the vacuum bagging reproducibility is given.

Confirmatory structural validation and refinement of the Recurrent Urinary Tract Infection Symptom Scale.

To confirm the structural validity of the Recurrent Urinary Tract Infection Symptom Scale (RUTISS), determining whether a bifactor model appropriately fits the questionnaire's structure and identifying areas for refinement. Used in conjunction with established clinical testing methods, this patient-reported outcome measure addresses the urgent need to validate the patient perspective. A clinically and demographically diverse sample of 389 people experiencing recurrent UTI across 37 countries (96.9% female biological sex, aged 18-87 years) completed the RUTISS online. A bifactor graded response model was fitted to the data, identifying potential items for deletion if they indicated significant differential item functioning (DIF) based on sociodemographic characteristics, contributed to local item dependence or demonstrated poor fit or discrimination capability. The final RUTISS comprised a 3-item symptom frequency section, a 1-item global rating of change scale and an 11-item general 'rUTI symptom and pain severity' subscale with four sub-factor domains measuring 'urinary symptoms', 'urinary presentation', 'UTI pain and discomfort' and 'bodily sensations'. The bifactor model fit indices were excellent (root mean square error of approximation [RMSEA] =0.041, comparative fit index [CFI] =0.995, standardised root mean square residual [SRMSR] =0.047), and the mean-square fit statistics indicated that all items were productive for measurement (mean square fit indices [MNSQ] =0.64 - 1.29). Eighty-one per cent of the common model variance was accounted for by the general factor and sub-factors collectively, and all factor loadings were greater than 0.30 and communalities greater than 0.60. Items indicated high discrimination capability (slope parameters >1.35). The 15-item RUTISS is a patient-generated, psychometrically robust questionnaire that dynamically assesses the patient experience of recurrent UTI symptoms and pain. This brief tool offers the unique opportunity to enhance patient-centred care by supporting shared decision-making and patient monitoring.

Simulation-Based Testing and Performance Evaluation of Vehicle Safety Functions

<div>The progressive development toward highly automated driving poses major challenges for the release and validation process in the automotive industry, because the immense number of test kilometers that have to be covered with the vehicle cannot be tackled to any extent with established test methods, which are highly focused on the real vehicle. For this reason, new methodologies are required. Simulation-based testing and, in particular, virtual driving tests will play an important role in this context. A basic prerequisite for achieving a significant reduction in the test effort with the real vehicle through these simulations are realistic test scenarios. For this reason, this article presents a novel approach for generating relevant traffic situations based on a traffic flow simulation in SUMO and a vehicle dynamics simulation in CarMaker. The procedure is shown schematically for an emergency braking function. A driving function under test faces the major challenges when the other road users commit driving errors. Therefore, the driving behavior models in this traffic flow simulation are modified in such a way that critical scenarios can arise because of these driving errors. In order to be able to make a statement about the correct behavior of the driving function under test in these traffic situations, objective criteria are necessary to evaluate the triggering behavior and the handling of the traffic situations. Based on the performance evaluation of the driving function under test, characteristic test scenarios are then identified that evenly cover the test space. The comparison of the deviations in covering this test space with full and the reduced dataset is small except in areas where there are no scenarios in both datasets. Finally, these selected scenarios are used to perform an application of the driving function under test. The procedure is exemplified for the triggering time and the maximum deceleration of an emergency braking function. When comparing the distributions, it is shown that the performance in both datasets improves in the same way when parameters are optimized. For example, the mean performance of the driving function increases by more than 0.3 in each case when optimizing the triggering time. Thus, it is no longer necessary to use all scenarios for parameterization in virtual driving tests.</div>

Residual stress measurement system of the general purpose powder diffractometer at CSNS

Neutron diffraction has become a well-established technique for the determination of residual stresses in various structural materials and bulk industrial products because of the unique deep penetration, three-dimensional mapping capability, and volume averaged bulk measurements characteristic of the scattering neutron beam. To conduct experiments in this research area, a residual stress measurement system was established on the general purpose powder diffractometer (GPPD) at the China Spallation Neutron Source (CSNS), which diffractometer now combines both powder diffraction and residual stress measurement conditions. The best d-space resolution of the diffractometer of medium-angle detector bank is Δd/d ≈ 0.33%. The gauge volume is precisely controlled by the four-blade slits, neutron Kirkpatrick–Baez (KB) mirror and radial collimators, and the general gauge volume is φ2*2 mm 3. The intelligent scanning positioning system established by GPPD achieves high-precision sample positioning, with an accuracy of up to 100μm. Until now, it has completed measurements on standard cycle samples of VAMAS shrink fit rings and plugs with known residual stress distributions, the results confirming the diffractometer’s high sensitivity and high accuracy to stress/strain gradients in materials or components. A large number of beam times are dedicated to user researches including residual stress studies of superalloys, high-entropy alloys, engineering steels, welds, and more. This demonstrates that the GPPD’s residual stress test system and the established test methods are feasible and effective.

On the low temperature tribological behaviour of brake block materials for railway applications under dry and icy conditions

Incidents in the Swedish railway have been observed where a significant and sudden loss of brake performance occurs in winter conditions, on trains equipped with composite tread brake blocks (CBB). There is a necessity to establish test methods that can be used for the evaluation of brake materials under well-controlled laboratory conditions, to facilitate an understanding of the friction mechanisms between brake block and steel wheel. This work sought to characterise the tribological behaviour of different CBB materials at room temperature and −15 °C, focusing on understanding the materials response with and without presence of ice in the contact, as well as the effect of temperature on the tribological behaviour. A pearlitic cast iron brake block was used as a reference and four CBB materials were investigated, two organic and two sintered. The sintered CBB showed similar friction coefficient to the reference material and higher than the organic CBB, both at room and at low temperature. This was also seen when ice was formed on the wheel steel counter surface at −15 °C. Higher wear was observed for the sintered CBB compared to the organic CBB. The results suggest that sintered CBB can provide higher friction under winter conditions compared to organic CBB.

Evaluation of fluid leakage at the coverall and glove interface in single and double glove conditions

BackgroundFluid leakage through the glove-protective clothing interface is an area of concern for many health care personnel, including emergency medical service providers, who may wear coveralls to protect themselves from multiple types of hazards. There is currently no established standard test method to specifically evaluate the barrier performance of the glove-protective clothing interface region for any personal protective equipment ensemble. ObjectiveThis study quantifies the fluid leakage at the coverall and glove interface using single and double gloving. MethodsA robotic arm, which can simulate upper extremity movements of health care personnel, was used to test 5 coverall models and an extended examination glove model in single and double glove conditions. ResultsThe results show that there was a significant difference in fluid leakage amounts between some of the coverall models and the number of glove layers studied. Findings also highlight that there is a high correlation between basis weight and stiffness of the coverall fabrics and the fluid leakage amounts. ConclusionsThese results underline that coverall constructed from thin and less stiff fabrics can result in lower fluid leakage levels. Also, there was no significant difference in fluid leakage amounts between single and double gloves when tested with each of the coverall models, with the exception of the coveralls with the highest basis weight and stiffness.

Research on Laboratory Test Method of Wave Energy Converter Wave-Wire Conversion Ratio in Irregular Waves

The laboratory test of the wave energy converter model is an important means to evaluate the performance of the device. At present, there are few performance tests for complete specifications under the irregular wave. Referring to the test methods and standards at home and abroad, combined with the actual test work experience in the laboratory, using the irregular wave power calculation formula with the effective wave height and the spectral peak period as parameters, then the wave-wire conversion ratio test method of the wave energy converter physical model under irregular waves in the laboratory is proposed. The method is applied to the basin test experiment of the physical model of the horn-shaped backward bent duct buoy (BBDB) wave energy converter. The research results show that the established test method and process of wave-wire conversion performance have achieved good application results in the irregular waves laboratory test, and can better reflect the device operating characteristics in real sea conditions. The test results provide data support for the model design of the wave energy converter in the next test stage, the demonstration test of the prototype, and the prediction of power generation in real sea conditions.

Shock absorber friction testing on a MacPherson suspension considering realistic mounting situation

Due to the specific layout of MacPherson suspension systems, the shock absorber is subject to a varying amount of load perpendicular to its own axis of displacement and is therefore generating a certain amount of friction. Especially at the presence of lateral forces at the tire contact patch, for example, in cornering situations, additional friction is generated. In order to accurately consider the actual amount of friction regarding vehicle dynamics and comfort, it is crucial to study shock absorber friction depending on the acting shear force. However, there is a shortage of knowledge considering realistic load situations of the shock absorber as present in the vehicle. Consequently, no commonly established test method exists to take the shear force into account. With the help of a static finite element analysis a test rig set-up is developed to investigate shock absorber friction replicating the suspension mounting situation. In the first step, a full suspension is transferred to a finite element model by a reverse engineering approach. Special attention is given to the spring forces, which show to be strongly multiaxial in terms of shear force reduction. Subsequently, the stress characteristics of the shock absorber tube, piston and the inner housing of the twin-tube shock absorber are investigated. Regarding various possible load cases for shock absorber testing under shear force, it becomes evident that one specific test set-up is able to reproduce the real load situation accurately. This test layout is implemented on a hydropulser test rig and allows the study of load-dependent friction characteristics.

Propidium Monoazide Combined With RT-qPCR Detects Infectivity of Porcine Epidemic Diarrhea Virus.

Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) allows sensitive detection of viral particles and viruses in epidemic samples but it cannot discriminate noninfectious viruses from infectious ones. Propidium monoazide (PMA) coupled with quantitative polymerase chain reaction (qPCR) was assessed to detect infectious viruses. Currently, there is no established test method to detect the infection of the porcine epidemic diarrhea virus (PEDV). In this study, propidium monoazide coupled with qPCR detects infectivity of PEDV. We optimized the method from the selection of primers, the working concentration of PMA, and the inactivation method using heat or ultraviolet (UV). The viruses which were treated with PMA before qPCR were inactivated using heat or UV. However, the addition of PMA alone did not affect the detection of live viruses, which indicates that a viral capsid break may be essential for PMA to bind to the genome. A repetition of the method on naked PEDV RNA suggests that it can be used to detect potentially infectious PEDV. The results indicated that an optimal plan of PMA could be extremely useful for evaluating infectious and noninfectious viruses.

The influence of the vibration test mode on the failure rate of electrical connectors

A new model for the reliability prediction was developed and validated in previous investigations in order to enable the determination of the failure in time (FIT) of electrical connectors from highly accelerated life tests (HALT). The established testing method considers the influence of temperature, thermal cycling and vibration on the failure rates of electrical connectors. Various stress levels, i.e. the combinations of different test parameters, were derived from the ZVEI Technical Guideline TLF 0214 for low voltage automotive connectors. The applied vibrational load was initially defined as a sinusoidal test mode. The aim of this study is to investigate the influence of the vibration test mode on the failure rates. Two commonly used automotive connectors are chosen and subjected to stresses in HALT under two different types of vibrational load. The sinusoidal test mode along with the random vibration test mode are taken into account. The influence of the vibration test modes is subsequently determined by comparing the numbers of failures. Additionally, the principles of determining the coefficient of vibration are discussed and the specific coefficients for the chosen connectors are calculated based on the test results. A guideline, derived from this investigation, to select an appropriate vibration mode and vibration level is provided in order to compare the reliability of different electrical connectors.

Quantifying Background Magnetic Fields at Marine Energy Sites: Challenges and Recommendations

Unknowns around the environmental effects of marine renewable energy have slowed the deployment of this emerging technology worldwide. Established testing methods are necessary to safely permit and develop marine energy devices. Magnetic fields are one potential cause of environmental effects and are created when electricity is generated and transmitted to shore. Further, the existing variation of the background magnetic field at sites that may be developed for marine energy is largely unknown, making it difficult to assess how much additional stress or impact the anthropogenic magnetic field may have. This study investigates two instruments for their ability to characterize the background magnetic fields at a potential marine energy site in Sequim Bay, WA. Based on this evaluation, this study recommends an Overhauser magnetomer for assessing the background magnetic field and demonstrates the use of this sensor at a potential marine energy site.

Determining Dynamic Properties of Elastomer-Dampers by Means of Impact Testing

BackgroundDamping elements made of elastomer materials are used in almost every mechanical system to prevent damage to components caused by impact-like excitations and the resulting high-frequency, large-amplitude oscillations. The dynamics of these operating conditions exceed the performance limits of conventional experimental testing methods, impeding validated predictions of the damper’s transmission behaviour.ObjectiveA method is proposed to directly investigate the influence of impacts on the transmission behaviour of elastomeric dampers by impact testing.MethodsTorsional-loaded elastomer dampers were experimentally investigated using a drop tower. During the experiment, a mass is brought into impact contact with a lever arm connected to the tested coupling. Measurements on resulting torsional oscillations and a comparison of the measurement results with a simple analytical model of the system allow for determining the coupling parameters stiffness and damping ratio.ResultsThe characteristic parameters stiffness and damping ratio of the elastomer damper were mapped as a function of excitation-amplitude and frequency. A comparison of drop-tower test results with servo-hydraulic measurements validated the determined parameters.ConclusionsDetermining the transmission behaviour of elastomeric dampers from highly dynamic and impact-induced oscillation states proved to be a good approach to supplement established testing methods.

Comparative study of electrical test methods on detecting transformer faults

Condition monitoring of distribution and power transformers is of utmost importance to utilities due to cost effectiveness concerns. The common faults that occur in transformers are short circuits and winding deformation. To date, there are many established test methods used to detect these faults. In this study, three test methods (insulation resistance (IR), transformer turn ratio (TTR), and frequency response analysis (FRA)) were compared to assess their effectiveness in detecting short circuit and winding deformation in a three-phase transformer. Based on the results, the three test methods were found to be capable of detecting short circuits. However, only TTR and FRA can detect winding deformation, and FRA can further indicate which phase is faulty. Therefore, it is concluded that FRA is more effective in detecting short circuit and winding deformation of a three-phase transformer.

Redefining feral dogs in biodiversity conservation

Unlike most feral domestic animals, ranging behavior, diet dependence, and human socialization have been used as criteria to define feral dogs. These criteria can obstruct wildlife conservation if decisions depend on identifying ferality in dogs. We argue that diet dependence and human socialization are unnecessary to define ferality in situations where dogs constitute a threat to wildlife. Human-dependent diet and sociability are not exclusive to house dogs; thus, they do not differentiate ferality with certainty, and they have no established testing methods or thresholds. Most notably, they obstruct management by complicating feral dog identification. As a case study, legislation in Chile surrounding dog management does not recognize the existence of feral dogs and bans the application of lethal methods on dogs. This impairs conservation because the current definition makes it impossible to distinguish if a dog is feral at first sight. This is a problem in the small-scale livestock industry, where goat and sheep losses are mainly caused by dogs. Stakeholders could kill attacking dogs to defend their livestock, risking a lawsuit if those dogs were owned, or continue to lose their livelihood. Neither option benefits livestock owners. To not hinder conservation, we propose feral dogs be defined based only on ownership status, ranging behavior, and location in the context of management, and offer a classification based on these criteria. However, we contend that whether a dog is feral is not important for decision-making. Instead, dogs should be controlled if they are found on any public space unaccompanied by humans.

The Evaluation of the Detection of Cr(VI) in Leather

The topic of hexavalent chromium (Cr(VI)) in leather has been debated throughout the whole supply chain for years. However, its significance has recently increased due to proposed changes in European legislation concerned with skin-sensitising substances suggesting that acceptable Cr(VI) concentrations in leather goods should be lowered from 3 mg kg−1 to 1 mg kg−1. The proposition of a stricter limit and current analytical difficulties created the need for a review of current standard test methods. The research presented in this paper investigates both the colorimetric (Part 1) and chromatographic (Part 2) methods under BS EN ISO 17075. The focus of the study was to identify possible sources of interference leading to large statistical variance in results and to define the limit of quantification with respect to the proposed new compliance limit. This study into the colorimetric method has shown that the presence of Cr(III), dyes, and proteins can be significant interferences, becoming critical at low Cr(VI) concentrations. Dilution factors worsen the problem of detecting low concentrations: a reliable quantitative detection of 0.01 mg kg−1 and 0.003 mg kg−1 Cr(VI) in solution are required at the 3 mg kg−1 and 1 mg kg−1 compliance limits in leather, respectively. BS EN ISO 17075 part 1 was shown to be incapable of reliably resolving to 3 mg kg−1 or below in leather. Part 2 shows a marked improvement in detection limits and reliability; however, data suggest that 1 mg kg−1 Cr(VI) is not reliably detectable in leather. Suggested improvements to the established test methods and a possible alternative are discussed.

Seasonal and Spatial Variations of Atmospheric Ammonia in the Urban and Suburban Environments of Seoul, Korea

Atmospheric ammonia is a significant pollutant throughout the year, necessitating standardized measurement and identification of emission factors. We performed a quantized evaluation of ammonia concentrations at various locations in and around Seoul, South Korea. The established testing methods of the Radiello Passive Sampler were used for ammonia sampling, and the method was validated using annular denuder sampling. Urban and suburban areas were studied to gain a deeper understanding of the factors responsible for ammonia pollution. This study aimed to establish the fluctuations in concentration over one year, by analyzing the seasonal and regional variation in ammonia concentration. Livestock and agricultural areas recorded the highest concentration of ammonia among all sites, with the highest concentration recorded in autumn. However, at most of the other studied sites, the highest and lowest ammonia concentrations were recorded during summer and winter, respectively. This study attempted to establish a correlation between ammonia concentration and temperature, as well as ammonia concentration and altitude.