Destructive Analysis Research Articles

The gender gap and the COVID-19 pandemic: An analysis of net Brazilian formal job destruction

This paper sets out to analyze gender behavior in the Brazilian labor market as a result of the economic effects of the COVID-19 pandemic. It focuses on job destruction and creation during the lockdown and implementation of social distancing throughout 2020. To do so, it uses the New General Register of Employed and Unemployed (NCAGED) and applies the Oaxaca-Blinder decomposition to net male and female job destruction at municipal level, in the 18 to 40 age group. In addition, inequality for every month of 2020, in terms of the pre- and post-pandemic context was verified. It was found that the initial months affected all formal workers but had an even greater effect on women. Another relevant contribution of this study is its inequality decomposition, where the findings show that it is largely due to structural effects.

Ancient basketry on the inside: X-ray computed microtomography for the non-destructive assessment of small archaeological monocotyledonous fragments: examples from Southeast Europe

This study proposes non-destructive assessment instrumentation, the X-ray MicroCT scanning, to evaluate archaeological basketry remains prior to any destructive analysis. Three case studies are originating from two archaeological sites in Southeast Europe, with three different stages of preservation (poor, sufficient and very good). In addition, there are two preservation modes—charring and desiccation—along with two conservation situations: treated and untreated with conservation agent fragments. The three different scenarios were chosen to explore the potential range of X-ray MicroCT scanning technology when applied to monocotyledonous small-sized archaeological remains. It was proved that this non-invasive X-ray method is particularly suitable for the often-disadvantaged ancient basketry remains.

Determining patterns in reducing the level of bio-destruction of thermally modified timber after applying protective coatings

This paper reports the analysis of the biological destruction of timber and the use of protective materials, which established that the scarcity of data to explain and describe the process of bioprotection, neglect of environmentally friendly agents lead to the biodegradation of timber structures under the action of microorganisms. Devising reliable methods for studying the conditions of timber protection leads to designing new types of protective materials and application technologies. Therefore, it becomes necessary to determine the conditions for the formation of a barrier for bacteria permeability and to establish a mechanism for inhibiting material biodegradation. Given this, the dependence has been derived to determine the proportion of destroyed material under the effect of microorganisms when using an antiseptic-hydrophobicizer, which makes it possible to evaluate biopenetration. Based on the experimental data and theoretical dependences, the share of destroyed timber was determined under the effect of microorganisms, which is equal to 1 for natural timber. At the same time, this value for thermally modified timber is 0.033, and, when it is protected with oil ‒ 0.009, respectively, exposed to the action of microorganisms for 60 days. It should be noted that the presence of oil, wax, and azure leads to blocking the timber surface from penetration. Such a mechanism underlying the effect of protective coating is likely the factor in the process adjustment, due to which the integrity of the object is preserved. Thus, a polymer shell was created on the surface of the sample, significantly reducing the penetration of microorganisms inside the timber, while the loss of timber mass during biodestruction did not exceed 2.5 %. Therefore, there are grounds to assert the possibility of targeted control over the processes of timber bio-penetration by using coatings capable of forming a protective film on the surface of the material

Mechanical and Microstructural Assessment of Inhomogeneities in Oxide Ceramic Matrix Composites Detected by Air-Coupled Ultrasound Inspection

Ceramic Matrix Composites (CMC) are promising materials for high-temperature applications where damage tolerant failure behavior is required. Non-destructive testing is essential for process development, monitoring, and quality assessment of CMC parts. Air-coupled ultrasound (ACU) is a fast and cost-efficient tool for non-destructive inspections of large components with respect to the detection of material inhomogeneities. Even though ACU inspection is usually used for visual inspection, the interpretation of C-scan images is often ambiguous with regard to critical defects and their impact on local material properties. This paper reports on a new approach to link the local acoustic damping of an oxide CMC plate obtained from ACU analysis with subsequent destructive mechanical testing and microstructural analyses. Local damping values of bending bars are extracted from ACU maps and compared with the results of subsequent resonant frequency damping analysis and 3-point bending tests. To support data interpretation, the homogeneous and inhomogeneous CMC areas detected in the ACU map are further analyzed by X-ray computed tomography and scanning electron microscopy. The results provide strong evidence that specific material properties such as Young’s modulus are not predictable from ACU damping maps. However, ACU shows a high, beneficial sensitivity for narrow but large area matrix cracks or delaminations, i.e., local damping is significantly correlated with specific properties such as shear moduli and bending strengths.

Cell Supply Chain Management with Approval and Surveillance Program

Although many battery safety standards and certifications are in place to minimize hazards or prevent safety-related incidents in the field, many publicized field incidents have increased public concerns about LiB safety. Most battery field incidents reported that the cell internal short circuit initiated the causes, and many experts blamed battery industries do not have the test system that can predict the field incident nor reflect how the incidents occur. The certification is required when a cell model is developed and just before that goes into the market.Some intended or unintended modifications are in the cell model after the model is certified, and some failure analysis reports blame unknown and unproven changes on the cell model were the root causes of the incidents.To eliminate and prevent the root causes of battery field incidents by unknown and unproven changes on the cell model, we developed a verification process named cell supply chain management with approval and surveillance program. The verification process makes a technical database of all the analysis and test results of each step of a cell model as its fingerprint. The database enables the process can identify and prevent any unknown and unproven changes in the cell model through its life span.The verification process has: 1) Cell electrical properties, 2) X-ray investigation and Destructive Physical Analysis with -electrode alignment check with overhang gap, - electrode assembly (Jelly roll) function and dimension measurement, - insulation mechanism check and measurement, 3) Electrode dimension measurement and composition and materials analysis, and 4) Electrolyte composition analysis.This paper explains and proposes the concept and analysis method of each verification process and validates the cell model verification process by comparing the analysis results of each step of a cell model manufacturing. Figure 1

Inspection of Carbon Fibre Reinforced Polymers: 3D identification and quantification of components by X-ray CT

In this reported research activity, a quantitatively 3D characterization at microscale of a CFRP reference composite with controlled porosity was performed by micro X-ray CT (µXCT); the results were compared with the destructive acid digestion analyses, following the procedure reported in the standard test method (ASTM D 3171 15) used to determine the composites’ porosity in General Aviation (GA). The μXCT analyses revealed a pore content of 4.37%v and identified the components, respectively, in 66%w of carbon fibres and 34%w of matrix; all obtained results demonstrated a high correspondence to the theoretical values of porosity (5.0%v) and components (67%w of carbon fibre and 33%w of polymer matrix). Instead, a not complete correspondence of the measures obtained by acid digestion was reported: 4.36%v of porosity, but 57%w of carbon fibre and 43%w of matrix. Therefore, the conformity of the μXCT results to the theoretical values demonstrated the feasibility and distinctiveness of the proposed NDT method for a rapid and reliable inspection of CRFP components used in GA in substitution of the standard DT and time-consuming digestion procedure. The proposed NDT inspection technique permitted not only the individuation and visualization in the reconstruction of the 3D analysed material of different components (e.g. pores, carbon fibres and polymer matrix) but also the 3D evaluation of the material composition with the identification and quantification of each constituent element.Graphical abstractE. Dilonardo*, M. Nacucchi, F. De Pascalis, M. Zarrelli, and C. GianniniInspection of Carbon Fibre Reinforced Polymers: 3D identification and quantification of components by X-ray CT

SP600125 Restored TNF-α-Induced Impaired Chondrogenesis in Bone Mesenchymal Stem Cells and Its Antiosteoarthritis Effect in Mice.

Inflammation, the main factor in the progression of osteoarthritis (OA), impairs the chondrogenesis of bone mesenchymal stem cells (BMSCs), which is an appealing process to target to regenerate impaired articular cartilage. This article aimed to investigate whether SP600125, a competitive ATP-specific inhibitor of the JNK pathway, could promote the chondrogenesis of BMSCs by enhancing their anti-inflammatory capacity. Chondrogenic differentiation was assessed by Alcian blue staining, immunofluorescence staining, and Western blot. The inflammation level was associated with the expression of matrix metalloproteinases (Mmp), evaluated by Western blot. Intra-articular injection of BMSCs pretreated with or without SP600125 was carried out on C57BL/6 mice after inducing OA by surgical destabilization of the medial meniscus. Safranin O-fast green (SO) and hematoxylin-eosin staining were employed to evaluate the cartilage destruction and immunohistochemical analysis was adopted to detect the expression of Col2 and Mmp-13 proteins in the mouse knee joint. We showed that SP600125 could inhibit inflammation induced by tumor necrosis factor-α (TNF-α) and promote the chondrogenesis of BMSCs. In the presence of TNF-α, the expression of aggrecan (Agc) and collagen type II alpha 1 (Col2) was significantly decreased compared with that in the control group and increased with the addition of SP600125. Moreover, the expression of Mmp-1, Mmp-3, and Mmp-13 was increased in BMSCs treated only with TNF-α and downregulated in SP600125-treated BMSCs. In vivo study showed that SP600125 could enhance protective effects of BMSCs on OA mice. Our results indicated that SP600125 rescued the chondrogenesis of BMSCs by inhibiting inflammation induced by TNF-α, which provides a theoretical basis for solving the problem of cartilage repair under inflammatory conditions.

Combining Signal Features of Ground-Penetrating Radar to Classify Moisture Damage in Layered Building Floors

To date, the destructive extraction and analysis of drilling cores is the main possibility to obtain depth information about damaging water ingress in building floors. The time- and cost-intensive procedure constitutes an additional burden for building insurances that already list piped water damage as their largest item. With its high sensitivity for water, a ground-penetrating radar (GPR) could provide important support to approach this problem in a non-destructive way. In this research, we study the influence of moisture damage on GPR signals at different floor constructions. For this purpose, a modular specimen with interchangeable layers is developed to vary the screed and insulation material, as well as the respective layer thickness. The obtained data set is then used to investigate suitable signal features to classify three scenarios: dry, damaged insulation, and damaged screed. It was found that analyzing statistical distributions of A-scan features inside one B-scan allows for accurate classification on unknown floor constructions. Combining the features with multivariate data analysis and machine learning was the key to achieve satisfying results. The developed method provides a basis for upcoming validations on real damage cases.

Damage Function of a Quasi-Brittle Material, Damage Rate, Acceleration and Jerk during Uniaxial Compression: Model and Application to Analysis of Trabecular Bone Tissue Destruction

A diversity of quasi-brittle materials can be observed in various engineering structures and natural objects (rocks, frozen soil, concrete, ceramics, bones, etc.). In order to predict the condition and safety of these objects, a large number of studies aimed at analyzing the strength of quasi-brittle materials has been conducted and presented in publications. However, at the modeling level, the problem of estimating the rate and acceleration of destruction of a quasi-brittle material under loading remains relevant. The purpose of the study was to substantiate the function of damage to a quasi-brittle material under uniaxial compression, determine the rate, acceleration and jerk of the damage process, and also to apply the results obtained to predicting the destruction of trabecular bone tissue. In accordance with the purpose of the study, the basic concepts of fracture mechanics and standard methods of mathematical modeling were used. The proposed model is based on the application of the previously obtained differentiable damage function without parameters. The results of the study are presented in the form of plots and analytical relations for computing the rate, acceleration and jerk of the damage process. Examples are given. The predicted peak of the combined effect of rate, acceleration and jerk of the damage process are found to be of practical interest as an additional criterion for destruction. The simulation results agree with the experimental data known from the available literature.

Micro Destructive Analysis for the Characterization of Ancient Mortars: A Case Study from the Little Roman Bath of Nora (Sardinia, Italy)

In this work, a protocol of a partially invasive sampling for the archaeometric characterization of ancient mortars from the little Roman Bath of Nora (Sardinia, Italy) is presented. Optical microscopy and different analytical techniques such as X-ray diffraction, X-ray fluorescence, thermo-gravimetric analysis, and physical/mechanical tests have been carried out on the mortars. These analyses were performed to investigate the chemical composition, alteration products, and binder pozzolanic activity. An innovative method of image analysis has been tested to obtain information about the size and shape of both the mortar aggregates and the binder/aggregate ratio. This new particle-size analysis has two different advantages: (i) it saves a huge volume of material compared to a classic granulometric classification through its use of a sieve and (ii) is eco-friendly in respect to the environment by saving a large volume of liquid waste derived from the acid attack for the separation of the insoluble aggregate from the soluble binder, as would be done for a common sieving. Results show a local provenance of the aggregates. The use of two different limestones for the mortars’ binder production was detected and probably this raw material belongs to the nearby Roman town of Karales (current day Cagliari).

Sorghum Grains Grading for Food, Feed, and Fuel Using NIR Spectroscopy.

Near-infrared spectroscopy (NIR) is a non-destructive, fast, and low-cost method to measure the grain quality of different cereals. However, the feasibility for determining the critical biochemicals, related to the classifications for food, feed, and fuel products are not adequately investigated. Fourier-transform (FT) NIR was applied in this study to determine the eight biochemicals in four types of sorghum samples: hulled grain flours, hull-less grain flours, whole grains, and grain flours. A total of 20 hybrids of sorghum grains were selected from the two locations in China. Followed by FT-NIR spectral and wet-chemically measured biochemical data, partial least squares regression (PLSR) was used to construct the prediction models. The results showed that sorghum grain morphology and sample format affected the prediction of biochemicals. Using NIR data of grain flours generally improved the prediction compared with the use of NIR data of whole grains. In addition, using the spectra of whole grains enabled comparable predictions, which are recommended when a non-destructive and rapid analysis is required. Compared with the hulled grain flours, hull-less grain flours allowed for improved predictions for tannin, cellulose, and hemicellulose using NIR data. This study aimed to provide a reference for the evaluation of sorghum grain biochemicals for food, feed, and fuel without destruction and complex chemical analysis.

Valorization of waste cabbage leaves by postharvest photochemical treatments monitored with a non-destructive fluorescence-based sensor.

The biosynthesis of polyphenolic compounds in cabbage waste, outer green leaves of white head cabbage (Brassica oleracea L. var. capitata subvar. alba), was stimulated by postharvest irradiation with UVB lamps or sunlight. Both treatments boosted the content of kaempferol and quercetin glycosides, especially in the basal leaf zone, as determined by the HPLC analysis of leaf extracts and by a non-destructive optical sensor. The destructive analysis of samples irradiated by the sun for 6days at the end of October 2015 in Skierniewice (Poland) showed an increase of leaf flavonols by 82% with respect to controls. The treatment by a broadband UVB fluorescent lamp, with irradiance of 0.38Wm-2 in the 290-315nm range (and 0.59Wm-2 in the UVA region) for 12h per day at 17°C along with a white light of about 20μmolm-2s-1, produced a flavonols increase of 58% with respect to controls. The kinetics of flavonols accumulation in response to the photochemical treatments was monitored with the FLAV non-destructive index. The initial FLAV rate under the sun was proportional to the daily radiation doses with a better correlation for the sun global irradiance (R2=0.973), followed by the UVA (R2=0.965) and UVB (R2=0.899) irradiance. The sunlight turned out to be more efficient than the UVB lamp in increasing the flavonols level of waste leaves, because of a significant role played by UVA and visible solar radiation in the regulation of the flavonoid accumulation in cabbage. The FLAV index increase induced on the adaxial leaf side was accompanied by a lower but still significant FLAV increase on the unirradiated abaxial side, likely due to a systemic signaling by mean of the long-distance movement of macromolecules. Our present investigation provides useful data for the optimization of postharvest photochemical protocols of cabbage waste valorization. It can represent a novel and alternative tool of vegetable waste management for the recovery of beneficial phytochemicals.

Exergy Analysis of an Ejector Cooling System by Modified Gouy–Stodola Equation

In this paper, exergy destruction analysis of a heat-assisted ejector cooling system has been carried out using a modified Gouy–Stodola equation. The modified Gouy–Stodola equation provides a more accurate and realistic irreversibility analysis of the system than the conventional Gouy–Stodola formulation. The coefficient of structural bond (CSB) analysis has also been executed to find the component whose operating variables affect the system’s total irreversibility at the most. Exergy analysis revealed that the maximum exergy loss happens in the ejector followed by the generator and condenser. The model predicted 40.84% of total irreversibility in the ejector at the designed conditions. However, total exergy destruction is found to be the most sensitive to the evaporator temperature. The CSB value of 12.97 is obtained in the evaporator using the modified exergy method. The generator appears to be the second sensitive component with the CSB value of 2.42, followed by the condenser with the CSB value of 1.628. The coefficient of performance of the system is found to be 0.18 at the designed conditions. The refrigerant R1234yf is considered in the system.

Energy and Exergy Analysis of a Lithium Bromide – Water (LiBr – H2O) Solar Absorption Refrigeration System

Energy and environmental analysis establishes an important role in industrial performance due to the ease at which improvement processes are developed to increase production targets while minimizing the level of pollution and operating costs. Additionally, the exergy destruction analysis defines a clearly structured understanding related to the performance of the thermodynamic cycle. Exergy and energy analysis of the thermodynamic process is investigated based on advanced theories of thermal sciences in order to improve their energy efficiency and to evaluate the exergy destruction developed during their operation. Consequently, thermodynamic efficiency and total exergy destruction studies are used to define the thermodynamic interactions between mechanical devices and to establish the optimal behavior of refrigeration systems under specific operating conditions. This paper performs an energy and exergy analysis of a single effect absorption refrigeration system using a LiBr - H2O solution as working fluid and cooling water for the cycle, considering flat plate solar collectors as heat sources for the absorption refrigeration system. The solar field has been modeled by using a proposed model based on meteorological data, and the cycle is modeled in Aspen Plus® simulation environment, obtaining the thermodynamic properties necessary for the subsequent calculations. Afterwards, some indicators are calculated, such as the Coefficient of Performance (COP), exergy yield and exergy destruction, using Engineering Equation Solver (EES). Consequently, by using MATLAB®, it has been possible to determine the set of parametric variables and operating conditions where a better energy performance of the system can be obtained through optimization algorithms improving the COP from 0.7374 to 0.8097 according to the meteorological conditions of Colombia.

Measurement of Environmentally Influenced Variations in Anthocyanin Accumulations in Brassica rapa subsp. Chinensis (Bok Choy) Using Hyperspectral Imaging

Dietary supplements of anthocyanin-rich vegetables have been known to increase potential health benefits for humans. The optimization of environmental conditions to increase the level of anthocyanin accumulations in vegetables during the cultivation periods is particularly important in terms of the improvement of agricultural values in the indoor farm using artificial light and climate controlling systems. This study reports on the measurement of variations in anthocyanin accumulations in leaf tissues of four different cultivars in Brassica rapa var. chinensis (bok choy) grown under the different environmental conditions of the indoor farm using hyperspectral imaging. Anthocyanin accumulations estimated by hyperspectral imaging were compared with the measured anthocyanin accumulation obtained by destructive analysis. Between hyperspectral imaging and destructive analysis values, no significant differences in anthocyanin accumulation were observed across four bok choy cultivars grown under the anthocyanin stimulation environmental condition, whereas the estimated anthocyanin accumulations displayed cultivar-dependent significant differences, suggesting that hyperspectral imaging can be employed to measure variations in anthocyanin accumulations of different bok choy cultivars. Increased accumulation of anthocyanin under the stimulation condition for anthocyanin accumulation was observed in “purple magic” and “red stem” by both hyperspectral imaging and destructive analysis. In the different growth stages, no significant differences in anthocyanin accumulation were found in each cultivar by both hyperspectral imaging and destructive analysis. These results suggest that hyperspectral imaging can provide comparable analytic capability with destructive analysis to measure variations in anthocyanin accumulation that occurred under the different light and temperature conditions of the indoor farm. Leaf image analysis measuring the percentage of purple color area in the total leaf area displayed successful classification of anthocyanin accumulation in four bok choy cultivars in comparison to hyperspectral imaging and destructive analysis, but it also showed limitation to reflect the level of color saturation caused by anthocyanin accumulation under different environmental conditions in “red stem,” “white stem,” and “green stem.” Finally, our hyperspectral imaging system was modified to be applied onto the high-throughput plant phenotyping system, and its test to analyze the variation of anthocyanin accumulation in four cultivars showed comparable results with the result of the destructive analysis.

Nondestructive recognition and differentiation of quasi‐spherical structures of biologic interest

AbstractBackgroundBiological findings in archaeological and paleontological contexts are not limited to bones. In particular, biological concretions can present valuable information regarding the health of the organisms under examination. However, these structures are often difficult to recognize and identify. Chemical analyses (e.g., Raman spectroscopy) can allow their identification but they are time‐consuming and destructive techniques, even if minimally so. In this research, the potential of nondestructive high magnification surface microscopy is investigated for the distinction of uroliths from other biological and nonbiological concretions, specifically gallstones, bezoars, gastric pellets, coprolites, eggs, gastroliths and geological concretions.MethodsThe external surfaces of uroliths, bezoars, gastric pellets, gallstones, coprolites, gastroliths, eggs and geologic concretions were examined microscopically at ×20, ×50 and ×200 magnification.ResultsMorphological surface appearance of uroliths was independent of producer phylogeny and chemical composition and presented as smooth surfaces with level, faceted or lobulated configurations. Gallstones also presented a large array of shapes with smooth or porous external surfaces. Gastric pellets, bezoars and coprolites could be distinguished from other biological stones by the common presence of hair, sand grains, bone fragments or hair. Presence of uniform pores permitted the recognition of egg shells. Distinguishing gastroliths and geologic concretions requires additional diagnostic criteria.ConclusionHigh magnification surface microscopy of biological concretions from reference collections permits a better understanding of biological concretions and their normal variation. In addition, it allowed the distinction of uroliths from most biological concretions. Nonetheless, gallstones constitute the major differential diagnosis of uroliths, and destructive chemical analyses may be ultimately required for their distinction.

Non-contact monitoring and evaluation of subsurface white etching area (WEA) formation in bearing steel using Rayleigh surface waves

The extreme dynamic loading on bearings during transient operating conditions in wind turbine gearbox instigates white etching area (WEA) formation and abrupt premature cracking. Thus there is much interest in developing an appropriate condition monitoring system to predict premature bearing failures instead of destructive microstructure analysis. Recently, guided ultrasonic waves have been extensively used for health monitoring of engineering components. This feasibility study aims to detect subsurface WEA formation using ultrasonic surface (Rayleigh) waves. WEA is replicated from impact loading experiments at 2 GPa contact pressure, with loading frequency 4.5 Hz on AISI 52100 bearing steel balls by varying test durations. Rayleigh wave signatures of the ball were analysed before and after experiments to recognize microstructural changes and confirmed using destructive microstructural analyses.

Structure-from-motion, multi-view stereo photogrammetry applied to line-scan sediment core images

Images of sediment cores are often acquired to preserve primary color information, before such profiles are altered by subsequent sampling and destructive analyses. In many cases, however, no post-processing of these images is undertaken to extract information, despite the fact that image processing can be used to describe and measure structures within the sample. Improvements of RGB (Red/Green/Blue) cameras and image processing algorithms now enable acquisition of high-resolution, metrically calibrated pictures called ortho-images, which have great potential. The way to obtain such ortho-images is by processing several raw images. We propose a semi-automated method that uses metrically calibrated targets to create the ortho-image, using Agisoft Photoscan software and a Python script. The method was tested on sediment cores up to 1.5 m long. It was compared to an approach without markers, one that uses only image matching. The proposed method showed better resolution and less distortion (GSD: 59 µm, RMSE: 7–18 µm). Images acquired without calibrated targets can still be used, by manually positioning points that can then be metrically calibrated. This approach is very useful for smartphone images taken in the field. There are many potential applications for such images of sediment cores, for instance as metric stratigraphic logs to facilitate description of the profile by unit, to study and measure structures (e.g. laminae, instantaneous deposits), or use of image registration or data fusion to create spatial landmarks for non-destructive sensors or destructive laboratory analyses. High-resolution metrically calibrated RGB images of sediment cores are simple to acquire and can play an important role in paleoclimate and paleoenvironmental studies.

Advantages in predicting conjugate freezing of meat in a domestic freezer by CFD with turbulence k-ɛ 3D model and a local exergy destruction analysis

The prediction of food freezing time has been one of the most relevant parameters for the design of freezing systems and the estimation of frozen food quality. However, the growing demand of frozen food and new energy efficiency standards in recent years, have generated interest in methodologies that describe precisely the evolution and distribution of temperatures and energy inefficiencies, such as conjugate food-air heat transfer models and exergy destruction analysis. In this work, the freezing time of meat inside a domestic freezer is determined using a conjugate three-dimensional (3D) model with the turbulent k-ɛ model for the airflow and the apparent enthalpy methodology for the phase change of water in the food. Additionally, a local exergy destruction analysis is performed to quantify the irreversibilities produced by viscous dissipation and heat transfer during the freezing process. The results obtained shows that the turbulent model describes properly the airflow velocity, obtaining a non-dimensional heat transfer (Nu¯) 64% higher than laminar model. Also, the 3D model describes precisely the physical domain, obtaining a Nu¯ 28% higher than the 2D model. Consequently, the turbulent 3D model obtains the best correlation with experimental results from literature. The exergy analysis determined a total exergy destroyed of 187 (W), mainly during the first hour of the freezing process. Two considerations were proposed to reduce the internal inefficiencies: controlling the airflow efficiently with baffles around the food and increasing the heat transfer rate by faster mechanisms, such as radiative or forced convective heat transfer.

Development of Cell Selection and Screening Method and Its Validation Process for the Multi-Combination Battery System

A commercial-off-the-shelf (COTS) cylindrical 18650 Li-Ion cells have been proven to be extremely reliable power sources from many electronic applications for long periods and adopted to the EV applications. The cylindrical cells have been considered a reliable power source for the aerospace battery system, thanks to their high energy and power density. However, some electronic applications' field failure histories and some test programs have indicated that batteries built with cylindrical 18650 cells in multi-cell configurations (series and parallel) have experienced safety issues under various test conditions. Another requirement of the aerospace battery is a long-life cycle under harsh operating conditions. A tiny potential risky outlier cell, which cannot be identified and detected during the cell manufacturing process, can severely affect the multi-combination battery system's safety and reliability, like the EV, ESS, and Aerospace battery system. This paper studied a cell selection and screening method and developed a validation process to evaluate the efficiency and reliability of the cell selection and screening process. A cell selection method includes visual inspection, mass and dimension check, some electrical tests (OCV, CCV, AC Impedance), capacity measurement, and cell level safety test according to widely accepted cell safety standards and battery industrial best practices of the lithium-ion battery. The cell screening method and procedure followed the process and criteria on the NASA technical document (Specification for Acceptance Testing Commercial Lithium-Ion Cells). This program adopted the 6-sigma concept on the data analysis of the cell selection and screening process, which rejects the outlier cells of the 3-sigma level of each test item. The validation process was designed with two test conditions: 1) cycle test on the regular operation of the Human-spaceflight's mission operating conditions and 2) accelerate test condition of the maximum (most severe) cycle condition of the cell makers specification document. The regular operation cycle test was designed to evaluate the screening process's efficiency, whether the 3-sigma level screening is acceptable to the performance of the battery system using all passed cell samples from the screening. The regular cycle test selects four types of 4S string battery groups from different combinations of the cell samples. And it was performed according to the Human-spaceflight's mission operating conditions to validate the 4S can meet the required cycle condition. On the other hand, the accelerated cycle test was designed to identify the difference of cell degradation and capacity decay between the two types of cell combinations by the cycle test. One group use cells randomly selected samples from the non-screen cell, and the other group used selected cells from passed group cell as a control sample. Both 4S strings were cycled at the accelerate test condition, the maximum (most severe) cycle condition of the cell makers specification document. The battery capacity decay and the cell's internal resistance changes by DC pulse technics were checked regularly every 100 cycles during the cycle test.The performance of both 4S was almost similar until 200 cycles. However, the non-screen 4S string's capacity decay speed was much faster and reach death after the 500 cycles, while the screened 4S runs without any severe capacity decline until 800 cycles. EIS (Electrochemical Impedance Spectroscopy) technique was applied to each cell of the 4S string. The DPA (destructive Physical Analysis) and electron microscope analysis were used to identify the electrode's degradation degree and study the cell failure mechanism during the accelerated cycle tests. The DPA and electron microscope analysis (SEM-EDS) identified that gradual damage of the cathode electrode material of the non-screened 4S string during the accelerated cycle test was the leading cause of the cell capacity decay. This research discusses that non-screened 4S string may have different characteristic cell among the four cells in the 4 S string compare to the screened 4S string. That can initiate the stress to the cell and then increase the cell internal resistance, following enhanced cell heat generation and eventually getting the cell imbalance. The cell imbalance and heat generation get the cell getting worse after 200 cycles and eventually kill the cell and 4S sting. This research concludes that the used cell screening process is effective and beneficial as a cell screening process for the multi-cell battery system, especially for the long-term cycle-life battery system, like EV, ESS, and aerospace applications. Figure 1