Test Material Research Articles

The performance analysis of hyper-heuristics algorithms over examination timetabling problems

In general, uncapacitated exam timetabling is conducted manually, which can be time-consuming. Many studies aim to automate and optimize uncapacitated exam timetabling. However, pinpointing the most efficient algorithm is challenging since most studies assert that their algorithms surpass previous ones. To identify the optimal algorithm, this research evaluates the performance of four algorithms: Hill climbing (HC), simulated annealing (SA), great deluge (GD), and tabu search (TS) in addressing the exam timetabling problem. The Kempe chain operator’s influence on optimization solutions is also examined. A simple random method is employed to select the low-level heuristic (LLH). The Carter (Toronto) dataset served as the test material, with each algorithm undergoing 200,000 iterations for comparison. The results indicate that the TS algorithm is superior, providing the best solution in 13 instances. The use of a tabu list enhanced the search process’s efficiency by preventing redundant modifications. The Kempe chain LLH exhibited a tendency towards achieving better solutions.

Advanced Excitation Symmetry Analysis Method (ESAM) for improved automated ultrasonic testing of polished materials

One of the strategic plans of the international NDT community is to define standards for developing advanced and digitalized non-destructive testing for automated set-up in mass production [1,2]. Excitation Symmetry Analysis Method (ESAM) are new coded signal processing tools exploring symmetry properties [3]. ESAM method aims to extract the nonlinearity from an ultrasound output by studying the property of symmetry of the transfer function. More precisely, the extraction of nonlinearity is done using basis function associated to a group which is associated to an a priori transfer function. As soon as the linear tomography uses the invariant properties of amplitude dependence, nonlinear tomography should exploit the invariance properties (or symmetry properties) of the complex system. Consequently, the invariance of the stationary properties of a complex medium would be supposed to be associated to a signature of the degradation, that will be extracted with advanced signal processing tools. The idea remains the same: studying the symmetry and more precisely the time reversal one and the inversion. A signal processing is used to measure discrepancies in the autocorrelation function (output signal called chirp coda) for two inputs: a signal and its inversion (pulse inversion). The experiments were done on different sample with and without cracks. It has been shown that when the nonlinearities are extracted from the chirp coda amplitude are non- negligible in crack area and nonlinearities are out of phase. Then, mixing symmetries like time reversal and pulse inversion enable the detection of defect that are difficult to detect with conventional ultrasound method. Indeed, for such crack a destructive mechanical analysis called Jomini is done where the material is polished and examined with microscope. The sensitivity improvement of chirp-coded signal processing has been validated in various domains. Coded excitation techniques, used in communication systems such as radar and sonar provide improved SNR without increasing the amplitude of excitation. The typical test equipment consists of a preamplifier Juvitek TRA-02 (0.02 - 5 MHz) connected to a computer, an amplifier ENI model A150 (55 dB at 0.3-35 MHz), a shear wave transducer Technisonic (2.25 MHz), and a longitudinal wave transducer Panametrics V155 (5 MHz). The experimental device was tested with the V3 calibration block, improved, and specially scaled in order to access to a wide range of multivalued parameters: mechanical properties, ultrasonic parameters (celerity and attenuation) and local geometric data.

Magnetic characterisation of ferromagnetic material

In magnetic and electromagnetic non-destructive testing, the physical properties of the material are often not well known or completely unknown. The design of the non-destructive testing systems that provide the magnetisation is often oversized in order to get enough magnetic saturation (e.g. in magnetic flux leakage method or in magnetoscopy method). An improvement of the device performances, expressed usually by the signal to noise ratio, can be obtained only when the designer of the device well knows the material characteristic in terms of magnetic curve, the curve that links the magnetic field strengths to the magnetic flux density. A good device must be able to saturate the material sample under test but not to overcame determinate values. In fact, when the magnetisation is low, the leakage of the flux is negligible, while when the magnetisation is too strong the material tends to be like air and the leakage flux is negligible too. The experimental characterisation is derived from the technique adopted for the testing of soft magnetic material adopted in electrical machines or electromechanical actuators. In the present paper will be presented some material characterisation useful for the non-destructive testing of railway track, metallic ropes or reinforcement iron.

Adaptive Critic Design for Event-Triggered Tracking Control in Discrete-Time on Linear Systems with Observers

This research pioneers an innovative methodology for the bespoke manufacturing of SquidSkin safety products, meticulously tailored to the distinct requisites of diverse industries encompassing medical, military, and defense sectors. The triple DES algorithm is a three instance of DES on same plain text in blocks of 64 bits and converts them to cipher text using keys of 168 bits. The triple DES encryption process creates cipher text, which is an unreadable, effectively indecipherable conversion of plaintext data, the version of information that humans can read and understand. The output of the encryption process, the triple DES cipher text, cannot be read until a secret triple DES key is used to decrypt it. The delineation of industry- specific manufacturing parameters mandates a nuanced approach to material composition and production processes, culminating in a paradigmatic advancement in safety product customization. Integral to this methodology is a rigorous analysis of industry-specific requirements, guiding the selection of optimal material compositions. This selection is underpinned by a meticulously designed material testing phase, ensuring adherence to exacting industry standards and performance benchmarks. Augmenting this paradigm is an imperative emphasis on fortifying the security framework underpinning the handling of proprietary manufacturing data. The proposal introduces an advanced cryptographic architecture, featuring encryption and decryption protocols. Approach assures heightened efficiency, unwavering reliability, and the preservation of proprietary information across varied industry sectors.

Effects of UVA on Flavonol Accumulation in Ginkgo biloba

Ginkgo is an economic tree species with high medicinal value, and flavonols are its main medicinal components. This research was conducted to investigate the molecular mechanism underlying the influence of Ultraviolet A (UVA) treatment on the synthesis of ginkgo flavonols with the aim of increasing their content. Ginkgo full-sib hybrid offspring were used as test materials. The phenylalanine ammonialyase (PAL), cinnamate 4-hydroxylase (C4H), and 4-coumarate: CoA ligase (4CL) enzyme activities, as well as flavonol contents, were measured under the same intensity of white light (300 μmol·m−2·s−1) with the addition of 20, 40, and 60 μmol·m−2·s−1 UVA separately after 20 days of treatment. The control check (CK) and treatment with the highest flavonol content were chosen for transcriptome sequencing analysis. The results showed that the PAL, C4H, and 4CL enzyme activities, as well as the flavonol and totalflavonol glycoside contents, of ginkgo hybrid progeny differed significantly under different UVA treatments. They showed a tendency to increase and then decrease, reaching a maximum value under UVA-4 (40 μmol·m−2·s−1 ultraviolet UVA light intensity) treatment. Ribonucleic acid (RNA) sequencing revealed the presence of 4165 genes with differential expression, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that the metabolic pathways commonly enriched across all four comparison groups included ‘phenylpropanoid biosynthesis’, while the pathways commonly enriched in green-leaf ginkgo UVA-4 treatment (TL), yellow-leaf ginkgo mutant CK treatment (CKY), and green-leaf ginkgo CK treatment (CKL) were related to ‘flavonoid biosynthesis’. Treatment with UVA light led to the increased expression of PAL and 4CL enzymes in the phenylpropanoid biosynthesis pathway, as well as increased expression of chalcone synthase (CHS), Flavanone 3-hydroxylase (F3H), and flavonol synthase (FLS) enzymes in the flavonoid biosynthesis pathway, thereby promoting the synthesis of ginkgo flavonols. In summary, the use of 40 μmol·m−2·s−1 UVA treatment for 20 days significantly increased the flavonol content and the expression of related enzyme genes in ginkgo hybrid offspring, enhancing ginkgo flavonoids and increasing the medicinal value of ginkgo.

Structural Complexity in Adapted Reading Materials: A Study Based on the Amount of Information

AbstractMost of the previous studies focused on lexical and syntactic features in adapted texts while little attention has been paid to the structural complexity from the perspective of the amount of information. In this study, we intend to examine the differences in structural complexity in adapted texts from the perspective of the amount of information at the lexical and grammatical levels. We also aim to identify the lexical and grammatical features that contribute most to such differences. The data used in this study were reading texts from Newsela, that is, reading materials for English learners under the educational system of K‐12 in the United States. This study yields several findings of interest. First, the adapted texts differ in the structural complexity at both lexical and grammatical levels in terms of their amount of information. Second, the differences display a decreasing trend. That is, the differences become smaller when the level of the text increases. Third, function words and part‐of‐speech trigrams with a preposition(s) and/or a noun(s) contribute most to the differences. The findings provide significant implications for the adaptation of language materials such as reading texts and test materials.

Investigating electromagnetic acoustic emission signals denoising for alloy materials non-destructive detecting: a CRQA method

Aiming at the problem that signals collected from local electromagnetic loading operations are usually mixed with background noises (especially white noise), this paper proposed an electromagnetic acoustic emission signal denoising technology based on cross recurrence quantification analysis (CRQA). Firstly, the decomposition layer and penalty factor of variational mode decomposition (VMD) are set by experience or optimization algorithm, and then the original signal is decomposed. Secondly, the main components are selected by the CRQA algorithm, and the electromagnetic acoustic emission signal after denoising is obtained by superposition reconstruction. The simulation and experimental results show that when 5dB noise is added, CRQA can effectively remove the background noises in electromagnetic acoustic emission signals compared to the correlation coefficient algorithm, and it can assist in realizing the high-precision non-destructive testing of alloy materials.

A Technique for In-Situ Displacement and Strain Measurement with Laboratory-Scale X-Ray Computed Tomography

Abstract Purpose: Establish a technique for simultaneous interrupted volumetric imaging of internal structure and time-resolved full-field surface strain measurements during in-situ X-ray micro-computed tomography (XCT) experiments. This enables in-situ testing of stiff materials with large forces relative to the compliance of the in-situ load frame, which might exhibit localization (e.g., necking, compaction banding) and other inhomogeneous behaviors.Methods: The system utilizes a combination of in-situ XCT, 2D X-ray imaging, and particle tracking to conduct volumetric imaging of the internal structure of a specimen with interrupted loading and surface strain mapping during loading. Critically, prior to the laboratory-scale XCT experiments, specimens are speckled with a high-X-ray-contrast powder that is bonded the surface. During in-situ loading, the XCT system is programmed to capture sequential 2D X-ray images orthogonal to the speckled specimen surface. A single particle tracking (SPT) or digital image correlation (DIC) algorithm is used to measure full-field surface strain evolution throughout the time-sequence of images. At specified crosshead displacements, the motion and 2D image sequence is paused for volumetric XCT image collection. Results: We show example results on a micro-tensile demonstration specimen additive manufactured from Inconel 718 nickel-chrome alloy. Results include XCT volume reconstructions, crosshead-based engineering stress, and full-field strain maps. Conclusion: We demonstrate an in-situ technique to obtain surface strain evolution during laboratory-scale XCT testing and interrupted volumetric imaging. This allows closer investigation of, for example, the effect of micro-pores on the strain localization behavior of additive manufactured metal alloys. In addition to describing the method using a representative test piece, the dataset and code are published as open-source resources for the community. Graphical abstract

Analysis and NDT applications of a gas discharge electroacoustic transducer

In this study, a gas discharge electroacoustic transducer (GDEAT) based on a pulsed electric discharge in the air under atmospheric pressure has been investigated. By evaluating acoustic pressure and recording amplitude-frequency characteristics of membranes, the acoustic characteristic of GDEATs have been obtained in the frequency range from 40 Hz to 4 MHz. The electro-thermo-acoustic processes have been studied in gas discharge systems of an open type where the electrode space is in a direct contact with the ambient. Some features of using the above-mentioned GDEATs in nondestructive testing (NDT) of materials have been demonstrated. It has been shown that, on one hand, the wear of both electrodes and insulation limits a work life of a transducer electrode system, but, from the other hand, this may lead to deposition of micro-particles on the surface of an object under test. The wear of electrode systems was evaluated quantitatively, and the results of the chemical analysis of deposited micro-particles have been presented. The use of a GDEATs for non-contact stimulation of local resonant vibrations in subsurface defects and visualizing vibrations by means of laser dopler vibrometry has been shown in the case of NDT of a glass fiber composite.

Masks and respirators for prevention of respiratory infections: a state of the science review.

SUMMARYThis narrative review and meta-analysis summarizes a broad evidence base on the benefits-and also the practicalities, disbenefits, harms and personal, sociocultural and environmental impacts-of masks and masking. Our synthesis of evidence from over 100 published reviews and selected primary studies, including re-analyzing contested meta-analyses of key clinical trials, produced seven key findings. First, there is strong and consistent evidence for airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other respiratory pathogens. Second, masks are, if correctly and consistently worn, effective in reducing transmission of respiratory diseases and show a dose-response effect. Third, respirators are significantly more effective than medical or cloth masks. Fourth, mask mandates are, overall, effective in reducing community transmission of respiratory pathogens. Fifth, masks are important sociocultural symbols; non-adherence to masking is sometimes linked to political and ideological beliefs and to widely circulated mis- or disinformation. Sixth, while there is much evidence that masks are not generally harmful to the general population, masking may be relatively contraindicated in individuals with certain medical conditions, who may require exemption. Furthermore, certain groups (notably D/deaf people) are disadvantaged when others are masked. Finally, there are risks to the environment from single-use masks and respirators. We propose an agenda for future research, including improved characterization of the situations in which masking should be recommended or mandated; attention to comfort and acceptability; generalized and disability-focused communication support in settings where masks are worn; and development and testing of novel materials and designs for improved filtration, breathability, and environmental impact.

Is Acceptable Noise Level Affected by the Number of Competitive Talkers? An Implication of Informational Masking and Listening in Dips for Acceptable Noise Level Mechanism

Background and Aim: The Acceptable Noise Level (ANL), which is an effective clinical tool for quantitative assessment of noise tolerance, is affected by some known variables related to both subject and testing materials. The present study examined how the characteristics of different babble noises may affect the ANL results in normal adult listeners. Methods: Forty Persian listeners with normal hearing participated. In addition to typical ANL testing with 12-talker noise, the ANL was obtained in 8 different conditions varying in number of talkers from 2 to 10 in the babble noises presenting forward and backward. Results: There was a significantly lower ANL for 2-talker babble compared to 4, 8, 10, and 12-talker babble in both forward and backward noise conditions. With the increase in talkers in noise, the ANL becomes worse but reaches almost a plateau with more than 4 talkers in babble noise. There was a statistically significant difference between 2-talker forward and 2-talker backward noises, with no difference for the other conditions. Conclusion: This finding that the ANL is affected by the number of talkers in babble noise and by the forward and backward background noise suggests that informational masking and listening in dip mechanisms are involved in ANL for normal hearing people at least. Keywords: Acceptable noise level; speech babble noise; listening in dips; informational masking; energetic masking

Selected properties of X120Mn12 steel welded joints by means of the plasma-MAG hybrid method

The article describes properties of welds made of high wear resistance X120Mn12 steel obtained by the hybrid PTA-MAG (plasma transferred arc – metal active gas) method. The specimens were 8 mm thick rectangular (200 mm × 350 mm) sheets metal. The analyzed butt welds were made with the parameters selected according to the criterion of smallest cross-sectional area of welds and the narrowest HAZ (heat affected zone). The outcome of metallographic tests of weld, HAZ and parent material, hardness distribution and XRD (X-ray diffraction) patterns of selected areas are presented. The IIT (Instrumented Indentation Test) method was used to describe the distribution of mechanical properties shaped by thermal cycle annealing of the welding process. The investigation shows that the application of the PTA-MAG hybrid heat source for welding manganese steel enables the use of the filler material ER307 (AWS-A5.9). The hybrid PTA-MAG welding system has the relatively high potential to be an efficient alternative to welding standard processes for X120Mn12 steel due to the HAZ overheating limitation. The zone of high-risk weld cracking is the part of the HAZ close to the fusion area that has been reheated during weldment formation. Heat input about 0.6 kJ/mm is needed to provide full deep penetration butt weld without defects and with a vapor capillary of wide enough to cover the weld gap. The increase of hardness in the welded joint is smooth distributed and going up to 10% compared to the base material. The width of HAZ was <1 mm. Intensive carbides precipitation in HAZ has been avoided successfully.

Experimental Testing of Filter Materials for Two-Stage Inlet Air Systems of Internal Combustion Engines

Experimental Testing of Filter Materials for Two-Stage Inlet Air Systems of Internal Combustion Engines

Exogenous Methyl Jasmonate (MeJA) Improves ‘Ruixue’ Apple Fruit Quality by Regulating Cell Wall Metabolism

‘Ruixue’ apples were used as the test material to study the effect of 10 μM methyl jasmonate (MeJA) on the quality and cell wall metabolism of apples after 18 d of storage. The results showed that MeJA significantly decreased the respiratory rate, reduced the titratable acid content and maintained a high soluble solids content. MeJA has been shown to suppress the activities and gene expressions of WSP, CSP, ISP, and cellulose in contrast to the control group, thereby maintaining a lower cell permeability and higher exocarp firmness. MeJA significantly decreased the expression of MdACS, MdACO, MdPL, Mdgal, and MdPG genes in the apple exocarp when compared to the control group. In addition, the overexpression of MdPL18 increased the content of cell wall polysaccharides such as WSP and CSP, enhanced cell wall-degrading enzyme activities, and accelerated fruit ripening and softening, whereas silencing MdPL18 did the opposite. Together, these results demonstrate that exogenous MeJA maintains the Ruixue apple fruit quality by regulating the metabolism of cell wall substances.

ENTEROCOCCUS FAECALIS AS AN ETIOLOGICAL FACTOR OF PURULENT PROCESSES IN SURGICAL PATIENTS: ANALYSIS OF BACTERIOLOGICAL RESEARCH RESULTS

Introduction. Opportunistic infections are often caused by microorganisms that are part of the normal human body microflora. Studying the role of microbiota in infectious pathology and the mechanisms of interaction between opportunistic microorganisms in microbial associations is crucial. Enterococcus faecalis is one such microorganism found in bacterial associations. The purpose of this study was to investigate the frequency of detecting E. faecalis in monoculture and as part of associations, the qualitative and quantitative composition of these associations, and the analysis of the variability in the pathogen’s susceptibility to antibiotics. Results and discussion. Out of 123 samples studied, Enterococcus bacteria were cultured in 38 cases, accounting for 30.9%. E. faecalis was isolated in monoculture in only 24.2% of all cultures of this species. Moreover, it was isolated in clinically significant concentrations (≥105 bacterial cells per 1 ml of the studied material) in only four out of eight cases. There is a difference in the susceptibility of cultures for groups of isolates where the concentration of microorganisms in the test material is <105 and ≥105 microbial cells per 1 ml. Conclusion. E. faecalis was present in 26.8% of isolates obtained from patients in the surgical department with purulent-inflammatory diseases. E. faecalis is mainly found in microbial associations. The susceptibility of E. faecalis to most of the antibiotics used in the study is higher in the group of isolates where this species of microorganism was present in concentrations equal to or higher than 105 microbial cells per 1 ml of the test material.

Effect of Protein (Bovine Serum Albumin) Content on the Frictional Behaviour of Soft Contact Lenses Using a Dynamic Oscillating Tribometer

Proteins can adsorb on the surface of materials, such as soft contact lenses (SCLs), and can affect the hydrophobicity, roughness, and surface properties of the contact lenses (CLs), which, in turn, can influence the friction between the lenses and the ocular surface. Excessive friction between contact lenses and the ocular surface can lead to discomfort for the wearer and may cause irritation or inflammation of the cornea, better known as corneal ulcers (keratitis). Bovine Serum Albumin (BSA) is often used as a standard protein in biocompatibility testing of materials, including contact lenses. One standard commercial contact lens was tested under lubricated conditions to access the coefficient of friction (CoF). The contact was lubricated with a tear-like fluid (TLF) solution containing six different concentrations of BSA. In all cases, good linearity of the results of the friction force was verified, suggesting that the first friction law can be applied to determine the value of the coefficient of friction. It was found that friction increases with the increase in protein concentration.

Statement of Retraction: Image processing algorithm for mechanical properties testing of high temperature materials based on time‐frequency analysis

Statement of Retraction: Image processing algorithm for mechanical properties testing of high temperature materials based on time‐frequency analysis

European union reference laboratory for feed additives: experience from 11 years organising proficiency testing

Feed additives are individually authorised within the European Union (EU) specifying the conditions of their use under real-world conditions. These criteria often include minimum or maximum level of their content in compound feed. In addition, feed business operators are obliged to indicate on the feed the level of the added content of the feed additive. While it is the task of the EU Member States official laboratories to perform control analyses to establish compliance with these provisions, the European Union Reference Laboratory for Feed Additives (EURL-FA) is organising since 2012 annual proficiency tests (PTs) for Member States’ National Reference Laboratories (NRLs). PTs organised by the EURL-FA are based on the principles that compound feed samples are prepared containing a known content of the target feed additive. These PT samples are then sent to the NRLs for analysis and the results reported back to the EURL-FA are subjected to statistical assessment to establish the laboratory specific proficiency to correctly analyse compound feed samples for the respective feed additive. In the current study, we looked at the outcome of this assessment across different PTs. The topics addressed were (1) the evaluation of the overall measurement capability of NRLs in respect to coccidiostats, trace elements and vitamin D3, (2) the challenge related to the preparation of homogenous test materials with particle-based feed additives, (3) a possible connection between the modified composition of preparations containing vitamin A and analytical results and (4) the impact of a training course on the proficiency of laboratories regarding carotenoid analysis.

Mechanical Properties of Oil Palm Trunk Lumber Using Parallel Strand Lumber (PSL)

This research is to study and investigates how the mechanical strength of oil palm trunk can be improved for parallel strand lumber (PSL) in the timber industry. Various methods are implemented by the wood industry for this purpose. The research uses an Instron Universal Testing Machine to perform mechanical testing on the oil palm trunk after undergoing PSL. Samples used for tensile testing adhere to the size guidelines outlined by the American Society of Testing Materials (ASTM). The results of the experiment indicate that the 1-inch strand has the highest mechanical strength compared to the 0.5 inch and 0.3-inch strand, as it has a higher fibre content that enables it to withstand applied loads or forces. However, the average sample of the 0.3-inch strand also exhibits similar mechanical strength as the 1-inch strand, due to the small size of the strand which allows for better absorption of the glue and stronger bonding with the surface.

Evaluating benefits of remote microphone technology for adults with hearing loss using behavioural and predictive metrics

Objective To investigate the benefit of remote-microphone (RM) systems for adults with sensory hearing loss. Design Speech recognition in quiet and in background noise was assessed. Participants with hearing loss underwent testing in two device conditions: hearing aids (HAs) alone and HAs with a RM. Normal hearing participants completed testing in the unaided condition. Predictive speech intelligibility modelling using the Hearing-Aid Speech Perception Index (HASPI) was also performed on recordings of HA processed test material. Study Sample Twenty adults with sensory hearing loss and 10 adults with normal hearing participated. Results Speech recognition for participants with hearing loss improved significantly when using the RM compared to HAs alone fit to Phonak’s proprietary prescription. Largest benefits were observed in the most challenging conditions. At the lowest signal-to-noise ratio, participants with hearing loss using a RM outperformed normal hearing listeners. Predicted intelligibility scores produced by HASPI were strongly correlated to behavioural results. Conclusions Adults using HAs who have significant difficulties understanding speech in noise will experience considerable benefits with the addition of a RM. Improvements in speech recognition were observed for all participants using RM systems, including those with relatively mild hearing loss. HASPI modelling reliably predicted the speech perception difficulties experienced.