Numerical Validation Methods

In the last years, numerical simulation has seen a great development thanks to costs reduction and speed increases of the computational systems. With these improvements, the mathematical algorithms are able to work properly with more realistic problems. Nowadays, the solution of a problem using numerical simulation is not just finding a result, but also to ensure the quality. However, can we say that the model results are correct regarding the behaviour of the system? In other words, how could we quantify the similarity between reality and simulations? To answer these questions, it is necessary to establish a validation criterion that allows an objective quantification of the difference between the results and the reality. Another way to say this is, how “true” our results are. In the case of numerical methods, the main objective is to replicate as closely as possible the behaviour of the "real" world through numbers. Normally, the results of the numerical methods are expressed in terms of graphics, pictures, etc. These results represent the view of reality that the chosen method provides. In order to affirm that the result of a numerical solution is fully consistent with the reality, it must be satisfied that: a. The mathematical model must incorporate all aspects of the real world. b. The numerical method has to solve exactly the equations of the mathematical modelling. The problem starts with these two conditions that guarantee the "truth" of the results, since none of them are fully accomplished and it must be admitted that the numerical prediction never completely matches the "real" world behaviour. Then you can only be sure that the numerical solution is a good approximation of the reality. Now, new questions arise: How much does the result obtained by a numerical method resemble the reality? How can we objectively quantify this similarity? The answers to these questions are those that give rise to the validation methods.Peer ReviewedPostprint (published version

La Compatibilidad electromagnética, un problema en la sociedad actual

Peer Reviewe

La Compatibilidad electromagnética, un problema en la sociedad actual

Peer Reviewe

Conducted Emissions Verification Setup Improvement for Space Applications

Just-before-test verification is needed to ensure that electromagnetic interference measurements are correctly performed. Some standards cover such specific requirements regarding test verification, this is the case of the ECSS-E-ST-20-07c for space applications. However, some drawbacks in the standard procedure have been identified, and in this work, we provide advice for improving the conducted emissions verification. For instance, we argue that the complete frequency range of the test should be evaluated during the verification of the test equipment, not just two single frequencies. Likewise, it is demonstrated how the standard verification setup introduces a significant mismatch that can compromise the accuracy of the result. Moreover, this work highlights the capabilities of novel instrumentation like high-end oscilloscopes that effectively provide convenient alternatives to improve further and simplify the measurement methodology while achieving even more accurate results if applied correctly.This work was supported in part by the European Union's Horizon 2020 research and innovation programme under Marie Skłodowska-Curie grant agreement No. 801342 (TecniospringINDUSTRY) and the Government of Catalonia's Agency for Business Competitiveness (ACCIÓ) and in part by the Spanish "Ministerio de Ciencia e Innovación" under project PID2019- 106120RBC31/AEI/10.13039/501100011033. EMC Barcelona's project under grant number SNEO-20211223 has received funding from CDTI, which is supported by "Ministerio de Ciencia e Innovación" and financed by the European Union – NextGenerationEU – through the guidelines included in the "Plan de Recuperación, Transformación y Resiliencia." Dr. Azpúrua has received funding from the StandICT.eu 2023 project, financed by the European Union's Horizon Europe - Research and Innovation Programme - under grant agreement no. 951972

Strategies Using Time-Domain Measurements for Radiated Emissions Testing in Harsh Environments

Performing in-situ radiated emissions measurements, that is, in locations different from a standard test site, can be a challenging task because of the high electromagnetic noise levels in the ambient. A harsh electromagnetic environment characterizes such sites, and it usually results in difficulties when discerning between emissions from the equipment under test (EUT) and electromagnetic fields generated by surrounding devices. Moreover, communication signals from broadcasting services are generally significantly higher than the standard emission limits, making it even harder to determine compliance. In this article, we present different techniques leveraging the advantages of time-domain measurement systems to provide effective and practical solutions to mitigate ambient noise’s effect on radiated electromagnetic interference measurements. First, the test method used is described, and pragmatic considerations are given to ensure reliable and repeatable measurements. Multichannel time-domain measurement systems are introduced as the fundamental tool for the proposed strategies. Subsequently, different study cases are evaluated with real test examples, highlighting several criteria intended to reduce the impact of ambient noise on the actual emissions measures produced by the EUT. Finally, a real application of those strategies for measuring a photovoltaic system is described. Overall, the methods employed and the main advantages of using full-time-domain FFT-based receivers are reviewed. In addition, the possibility of incorporating this article’s outcomes into forthcoming electromagnetic standards about in-situ radiated emission measurements is also debated.This work was supported in part by the European Partnership on Metrology, co-financed by the European Union's Horizon Europe Research and Innovation Programme and by the Participating States under Project 21NRM06 EMC-STD, and in part by the "Ministerio de Ciencia e Innovación" through the Project DIN2021-012003 under Grant MCIN/AEI/10.13039/501100011033 and Grant PID2019-106120RBC31/AEI/10.13039/501100011033. EMC Barcelona was supported by the "Ministerio de Ciencia e Innovación" and financed by the European Union—NextGenerationEU, which has received funding from CDTI through the guidelines included in the "Plan de Recuperación, Transformación y Resiliencia" under Grant SNEO-20211223. Dr. Azpúrua works as a standardization expert of the StandICT.eu 2023 Project, which was financed by the European Union's Horizon Europe—Research and Innovation Programme—under Agreement 951972

Measuring Receiver Benchmark for Conducted and Radiated Emissions Testing in Space Applications

This paper compares the measurement results obtained from three different implementations of measuring receivers regarding spectral level accuracy. The objective is to validate the suitability of direct sampling electromagnetic emissions measurements with respect to those delivered by a high-end EMI receiver in frequency swept and FFT modes. The experimental setups follow the verification methods described in the ECSS-E-ST-20-07C Rev.2 standard to set realistic and reproducible conditions. Between 50 kHz and 100 MHz, common mode and differential mode currents are measured when multisine excitation signals with controlled amplitude profiles are used as references. Subsequently, conducted and radiated emissions tests are run to investigate the correlation between measurements with the different receivers. The instruments used are a low-cost USB digitiser Picoscope PS5444D, a high-performance benchtop oscilloscope R&S RTO6 and the R&S ESW44 full-compliant EMI test receiver. The analysis concludes that the emissions measurements performed with the direct sampling approach are excellent for the intended application, exhibiting an accuracy comparable to the dedicated EMI test receiver and a well adequate dynamic range and noise level.The project (21NRM06 EMC-STD) has received funding from the European Partnership on Metrology, co-financed by the European Union's Horizon Europe Research and Innovation Programme and by the Participating States. EMC Barcelona's project under grant number SNEO-20211223 has received funding from CDTI, which is supported by "Ministerio de Ciencia e Innovación" and financed by the European Union - NextGenerationEU - through the guidelines included in the `Plan de Recuperación, Transformación y Resiliencia". Dr. Azpúrua has received funding from the StandICT.eu 2023 project, financed by the European Union's Horizon Europe - Research and Innovation Programme - under grant agreement No. 951972. Dr. Pous' work was supported in part by the European Union's Horizon 2020 research and innovation programme under Marie Skłodowska-Curie grant agreement No. 801342 (TecniospringINDUSTRY) and the Government of Catalonia's Agency for Business Competitiveness (ACCIÓ) and in part by the Spanish "Ministerio de Ciencia e Innovaci´on" under project PID2019-106120RBC31/AEI/10.13039/501100011033

Efficient In situ Assessment of Radiated Emissions using Time-Domain Measurements

This paper presents three different case studies where the electromagnetic emissions of atypical equipment (a photovoltaic system, a passenger boarding bridge and a pallet washing machine) have been assessed in situ using time-domain measurement systems. The magnetic field (150 kHz-30 MHz) and electric field (30 MHz-1 GHz) emissions are considered. The technical challenges encountered and the solutions adopted for each scenario will be highlighted by describing the methodology employed. The goal is to relate the empirical knowledge and know-how gained through those study cases with the specific requirements and procedures defined in the standards. In that sense, multi-channel time-domain emissions measurements have been essential to carry out those measurement campaigns efficiently. The results are summarised as lessons learned during the experiences reported in this article. This work is relevant to support the revision or development of standards about in situ EMC testing as it provides helpful evidence to validate alternative radiated emissions measurement methods under realistic conditions.The project (21NRM06 EMC-STD) has received funding from the European Partnership on Metrology, co-financed by the European Union's Horizon Europe Research and Innovation Programme and by the Participating States. EMC Barcelona's project under grant number SNEO-20211223 has received funding from CDTI, which is supported by ''Ministerio de Ciencia e Innovación'' and financed by the European Union – NextGenerationEU – through the guidelines included in the "Plan de Recuperación, Transformación y Resiliencia." Dr. Azpúrua has received funding from the StandICT.eu 2023 project, financed by the European Union's Horizon Europe - Research and Innovation Programme - under grant agreement no. 951972

Time-Domain Electromagnetic Characterization of Reaction Wheel for Space Applications

The electromagnetic characterization of reaction wheels is crucial to comply with the demanding ac magnetic field cleanliness requirements of space science missions, thus, preventing interference on sensitive onboard instrumentation. Therefore, a complete assessment, including the measurement of the magnetic flux vector at different operational modes and under dynamic conditions, is proposed as a contribution beyond conventional testing methodologies. This article investigates the worst-case magnetic field emissions experimentally, using a test setup based on a multichannel acquisition and multidomain postprocessing system. The focus of the measurement campaign was on the low-frequency range (10 Hz–2 kHz). Moreover, capturing the B-field in the time-domain enabled further analysis, that is, complementary outputs for understanding the electromagnetic performance of the reaction wheel. As a result, we can relate the wheel rotation with the current and the magnetic fields, compute the field orientation, and evaluate in-band interference for the magnetic field.This work was supported in part by European Union's Horizon 2020 research and innovation programme under Marie Skłodowska-Curie under Grant Agreement 801342 (TecniospringINDUSTRY) and the Government of Catalonia's Agency for Business Competitiveness (ACCIÓ) and in part by the Spanish "Ministerio de Ciencia e Innovación" under Project PID2019-106120RBC31/AEI/10.13039/501100011033. EMC Barcelona's project under grant number SNEO-20211223 has received funding from CDTI, which is supported by "Ministerio de Ciencia e Innovación" and financed by the European Union – NextGenerationEU – through the guidelines included in the "Plan de Recuperación, Transformación y Resiliencia.

A20 deficiency causes spontaneous neuroinflammation in mice

Background: A20 (TNFAIP3) is a pleiotropic NFκB-dependent gene that terminates NFκB activation in response to inflammatory stimuli. The potent anti-inflammatory properties of A20 are well characterized in several organs. However, little is known about its role in the brain. In this study, we investigated the brain phenotype of A20 heterozygous (HT) and knockout (KO) mice. Methods: The inflammatory status of A20 wild type (WT), HT and KO brain was determined by immunostaining, quantitative PCR, and Western blot analysis. Cytokines secretion was evaluated by ELISA. Quantitative results were statistically analyzed by ANOVA followed by a post-hoc test. Results: Total loss of A20 caused remarkable reactive microgliosis and astrogliosis, as determined by F4/80 and GFAP immunostaining. Glial activation correlated with significantly higher mRNA and protein levels of the pro-inflammatory molecules TNF, IL-6, and MCP-1 in cerebral cortex and hippocampus of A20 KO, as compared to WT. Basal and TNF/LPS-induced cytokine production was significantly higher in A20 deficient mouse primary astrocytes and in a mouse microglia cell line. Brain endothelium of A20 KO mice demonstrated baseline activation as shown by increased vascular immunostaining for ICAM-1 and VCAM-1, and mRNA levels of E-selectin. In addition, total loss of A20 increased basal brain oxidative/nitrosative stress, as indicated by higher iNOS and NADPH oxidase subunit gp91phox levels, correlating with increased protein nitration, gauged by nitrotyrosine immunostaining. Notably, we also observed lower neurofilaments immunostaining in A20 KO brains, suggesting higher susceptibility to axonal injury. Importantly, A20 HT brains showed an intermediate phenotype, exhibiting considerable, albeit not statistically significant, increase in markers of basal inflammation when compared to WT. Conclusions: This is the first characterization of spontaneous neuroinflammation caused by total or partial loss of A20, suggesting its key role in maintenance of nervous tissue homeostasis, particularly control of inflammation. Remarkably, mere partial loss of A20 was sufficient to cause chronic, spontaneous low-grade cerebral inflammation, which could sensitize these animals to neurodegenerative diseases. These findings carry strong clinical relevance in that they question implication of identified A20 SNPs that lower A20 expression/function (phenocopying A20 HT mice) in the pathophysiology of neuroinflammatory diseases