In the paper, we report our research on the improvement of thermal efficiency of refrigerated trailers by modification of their wall structure by placing a layer of phase change material inside them. ...The research was carried out in the field of transport, meeting the requirements of all classes provided for in the ATP agreement for refrigerated trailers. As part of the research, we formulated a numerical model of the proposed design of the refrigerator walls, which was subsequently validated by comparing the modeling results with the results of experimental tests carried out on a test bench designed specifically for this purpose. Based on the validated simulation conditions, we formulated the numerical model of a full-scale refrigerated semi-trailer, which was numerically tested under the conditions specified in the ATP Agreement. The results proved that adding a 6 mm layer of the SP-24 phase change material in each of the walls of the cold store allows the temperature inside the trailer to be kept below −20 °C for a period of 24 h without the need to supply cold from the outside during operation. The passive refrigerated semi-trailer system implemented in this manner with 6 mm PCM layer allows for a reduction in primary energy consumption by up to 86% in a period of 22 h. The mentioned percentage did not take into account the efficiency of the cooling system of the phase change material.
The following paper describes investigations on the impact of harsh environment on shear and tensile strength of multi-material adhesive joints. The samples were made from carbon fiber – epoxy ...composites, aluminum and two types of advanced steels: abrasion resistant and high-strength. In order to assess the suitability of structural bonding for this sort of applications, it was decided to test two different epoxy-based adhesives, designed for moderate and elevated operating temperatures. The harmful conditions were simulated by means of humidity-temperature cycling tests, according to the SAE standard. The obtained results revealed that even moderately harsh humidity-temperature loads can cause debonding of the joints, even if no external forces are applied. In order to gain insight into this phenomenon, a series of finite element analyses was performed, simulating the exposure of the samples to the chosen environmental conditions. Based on these studies, the temperature expansion coefficient was identified as the crucial factor for the performance of the joints made from dissimilar materials. The results of the described experiments, confirmed by numerical calculations, constitute a guideline for multi-material structural design, supporting this constantly growing branch of modern engineering with a relevant input.
Climate change is forcing action to reduce energy consumption and greenhouse gas emissions. An extremely important area of high-polluting energy consumption is material transport and, within this, ...the transport of chilled goods, including deep-frozen goods, is an important contributor. Phase change materials (PCMs) can have an important role in reducing energy consumption for the transport of chilled goods, but the current state of knowledge is not sufficient to bring the solution into popular use. This article includes a study of the effect of implementing microencapsulated PCM (mPCM) in polyurethane foam (PU) on the insulation performance of refrigerated trailer walls in low-temperature transport. In this research, mPCM was used, characterised by a phase-change heat in the range of 170–195 kJkg and a phase change temperature in the range from −10 °C to −9 °C. The studies performed show the potential of using mPCMs to improve the insulation performance of the walls of refrigerated trailers. Containing mPCM in the amount of 5.0% wt. placed throughout the entire volume of the wall can improve thermal conductivity of the wall for up to 15% in peak and 4.5% (0.2792 Wm2K without mPCM and 0.2665 Wm2K with mPCM) in the phase change temperature range. Out of the range of phase change temperatures, the thermal conductivity of the wall with mPCM is worse for 2.72% than in walls without PCM. Problems that need to be tackled were also identified, before the solution can be put into everyday use, i.e., finding the technology to increase the proportion of mPCMs relative to PU.
•NIR-HSI models predicted more accurately Corg contents than FT-NIR models.•Accuracy of predicting Nt content using NIR-HSI and FT-NIR data was similar.•The ANN models had better accuracy than PLSR ...models.
The aim of this study was to compare the performance of FT-NIR spectroscopy and near-infrared hyperspectral imaging (NIR-HSI) in predicting the Corg and Nt contents in mine soils. The mine soil samples were measured for the Corg and Nt contents and their NIR spectra were recorded (1000–2500 nm). Predictive models were developed using 126 samples with partial least square regression (PLSR) or artificial neural networks (ANN) and validated with 58 independent samples. The NIR-HSI based models had distinctly higher accuracy of Corg content prediction than those based on FT-NIR data in both PLSR and ANN methods, as indicated by lower of standard errors of prediction. The prediction accuracy for the Nt content was similar for the two spectral methods and both chemometric approaches tested. The study showed that despite lower spectral resolution the NIR-HSI spectra retained all the information needed for accurate prediction of Corg and Nt contents.
The aim of this special collection is to bring together the expertise of scientists and engineers from universities and industry who work in the fields of Structural Health Monitoring, ...Non-Destructive Evaluation and Condition Monitoring. Networking between diagnostic systems designers and system users is crucial to the successful operation of many SHM systems. The study of damage detection, localization and assessment are important to the rapidly growing area of SHM.
Hyperspectral imaging (HSI) is a remote sensing technique that has been successfully applied for the task of damage detection in glass fibre-reinforced plastic (GFRP) materials. Similarly to other ...vision-based detection methods, one of the drawbacks of HSI is its susceptibility to the lighting conditions during the imaging, which is a serious issue for gathering hyperspectral data in real-life scenarios. In this study, a data conditioning procedure is proposed for improving the results of damage detection with various classifiers. The developed procedure is based on the concept of signal stationarity and cointegration analysis, and achieves its goal by performing the detection and removal of the non-stationary trends in hyperspectral images caused by imperfect lighting. To evaluate the effectiveness of the proposed method, two damage detection tests have been performed on a damaged GFRP specimen: one using the proposed method, and one using an established damage detection workflow, based on the works of other authors. Application of the proposed procedure in the processing of a hyperspectral image of a damaged GFRP specimen resulted in significantly improved accuracy, sensitivity, and F-score, independently of the type of classifier used.
In this paper slant stack (SL) transform is presented and its application for processing of multi-modal dispersive Lamb waves snapshots is proposed. The SL transform can facilitate the evaluation of ...dispersion curves based on a set of signals captured at the structure׳s surface. The presented technique leads explicitly to the frequency-phase-velocity representation of the processed signals. Theory behind the technique is presented and the SL results are compared to those obtained using the 2D discrete Fourier transform. The SL is used to process data acquired from an aluminum plate and to investigate anisotropic properties of a composite plate.
•We propose application of slant stack transform for processing Lamb wave signals.•The technique leads to the frequency-phase-velocity representation of the signals.•We compare results of the slant stack and the 2D discrete Fourier transform.•We apply the slant stack for simulated and measured data from an isotropic plate.•We apply the slant stack to investigate anisotropic properties of a composite plate.
In this work, the deformation behavior of MXene-based polymer composites with bioinspired brick and mortar structures is analyzed. MXene/Polymer nanocomposites are modeled at microscale for ...bioinspired configurations of nacre-mimetic brick-and-mortar assembly structure. MXenes (brick) with polymer matrix (mortar) are modeled using classical analytical methods and numerical methods based on finite elements (FE). The analytical methods provide less accurate estimation of elastic properties compared to the numerical one. MXene nanocomposite models analyzed with the FE method provide estimates of elastic constants in the same order of magnitude as literature-reported experimental results. Bioinspired design of MXene nanocomposites results in an effective increase of Young's modulus of the nanocomposite by 25.1% and strength (maximum stress capacity within elastic limits) enhanced by 42.3%. The brick and mortar structure of the nanocomposites leads to an interlocking mechanism between MXene fillers in the polymer matrix, resulting in effective load transfer, good strength, and damage resistance. This is demonstrated in this paper by numerical analysis of MXene nanocomposites subjected to quasi-static loads.
The paper contains a survey of mobile scanning systems for measuring the railway clearance gauge. The research was completed as part of the project carried out for the PKP (PKP Polish Railway Lines ...S.A., Warsaw, Poland) in 2011-2013. The authors conducted experiments, including a search for the latest solutions relating to mobile measurement systems that meet the basic requirement. At the very least, these solutions needed to be accurate and have the ability for quick retrieval of data. In the paper, specifications and the characteristics of the component devices of the scanning systems are described. Based on experiments, the authors did some examination of the selected mobile systems to be applied for measuring the clearance gauge. The Riegl (VMX-250) and Z+F (Zoller + Fröhlich) Solution were tested. Additional test measurements were carried out within a 30-kilometer section of the Warsaw-Kraków route. These measurements were designed so as to provide various elements of the railway infrastructure, the track geometry and the installed geodetic control network. This ultimately made it possible to reduce the time for the preparation of geodetic reference measurements for the testing of the accuracy of the selected systems. Reference measurements included the use of the polar method to select profiles perpendicular to the axis of the track. In addition, the coordinates selected were well defined as measuring points of the objects of the infrastructure of the clearance gauge. All of the tested systems meet the accuracy requirements initially established (within the range of 2 cm as required by the PKP). The tested systems have shown their advantages and disadvantages.
The paper deals with analysis of recognition of surface quality with reflective structures. Such surfaces are common in metallic materials cut using a saw or polished. There are no easy methods to ...identify such elements after machining. This issue is crucial in the industry for quality control as recognition of the elements, for instance after failure, allows for a detailed study of their manufacturing process. Firstly, six cuboid steel elements were obtained from a larger beam with a circular saw. Then, the bidirectional reflection distribution function (BRDF) was obtained for each element 3 times. The BRDF profiles were used in custom recognition software based on the K-nearest neighbors algorithm. In total, 140 variants of the classifier were tested and analyzed. Additionally, each variant was solved 200 times with different splits of the dataset. The results showed a high multiclass accuracy in all considered variants of the algorithm, with multiple variants achieving 100% accuracy. This level of performance was attained with only 1 to 2 training samples per class. Its low numerical complexity, easy experimental procedure, and “one-shot” nature allow for fast recognition, which is crucial in industrial applications.
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