Possibilities and limitations of active battery management systems for lithium-ion batteries

(English) Lithium-Ion Batteries (LIBs) are being used in more and more areas of application. At the same time, their chemical composition and their designs are constantly evolving. Major developments are also taking place in the field of Battery Management Systems (BMSs), which are essential for the safe operation of LIBs. The focus is on intelligent charge redistribution between individual cells, called Active Balancing (AB). This thesis deals with the possibilities and limitations of AB. An empirical long-term experiment provides new insights into the ageing behaviour of batteries that are actively balanced during their entire service life. The main objective of this work is to to demonstrate influences on the ageing behaviour of batteries that are still unknown at present. A literature study shows that previous work in this area is often based on theoretical approaches and rarely has a functional proof through measurement results. Most significant statements from literature are examined. These include the increase in discharge capacity, energy efficiency and service life associated with AB, as well as lower parameter variation of the individual cells installed in the battery. Before starting the empirical experiment, the current state of the art is captured and a universal AB topology is selected from a large number of known systems. The operating behaviour as well as the balancing algorithms are explained in detail in order to be able to understand the influences occurring during the ageing of the batteries. The ageing experiment itself is a comparison test between commercial Passive Balancing (PB) and the novel AB. Two identical battery packs are aged under uniform conditions, but with the two different BMSs mentioned above. At the end of the ageing process, the battery packs are disassembled and the parameters of all individual cells are determined for further investigation. The main contribution of this work is the proof of effects through AB, especially with large battery loads. Both the increase in discharge capacity and the service life are demonstrated. The work shows how parameter variation of individual cells can be made visible during operation. It also presents diagnosis and calculation methods. The energetic efficiency of the batteries cannot be increased, since the self-consumption of the power electronics of the AB system is always higher than with PB. However, the overall efficiency of the battery increases due to an increase in capacity and an extension of the service life. The thesis also shows that with lower battery loads, the use of AB is not beneficial any more or may lead to negative effects. In such applications conventional PB is sufficient. The results obtained during pack ageing are additionally substantiated and extended by the measurement results of the individual cells. At the end of the thesis, all results and contributions are summarised. Suggestions for optimisation as well as further research ideas are presented as a possible starting point for further scientific studies.(Català) Les bateries d’ions de liti (Lithium Ion Batteries, en anglès) s’usen en més aplicacions. Al mateix temps, la seva composició química i dissenys estan en evolució constant. Els sistemes de gestió del bateries (Battery Management Systems, en anglès), que són essencials per l’operació de les LIB, també estan en constant evolució. El focus principal està en la distribució intel·ligent de càrrega elèctrica entre cel·les individuals, l’anomenat balanceig actiu (Active Balancing, en anglès). Un assaig empíric, de llarga durada, com el dut a terme en aquest treball, dona molt informació en el procés d’envelliment de les cel·les durant tota la seva vida. El principal objectiu d’aquest treball és demostrar les influències encara desconegudes en el procés d’envelliment de les cel·les. L’estudi de la literatura mostra que el treball previ en aquesta àrea està sovint basat en aproximacions teòriques i estranyament ensenya resultats empírics que ho corroborin. En aquest treball s’examinen la majoria de presumpcions que es poden trobar a la literatura. Aquestes inclouen l’increment en la capacitat, l’eficiència energètica i la vida útil associada a un balanceig actiu de les cel·les, així com la reducció de la variació dels paràmetres de cada cel·la en una bateria. Abans de procedir amb l’experiment empíric, es revisa l’estat de l’art en els aspectes fonamentals per aquest estudi. També se selecciona una tipologia de sistema de balanceig actiu per tal de realitzar l’experiment. El treball detalla el procediment d’operació així com l’algoritme de balanceig actiu implementat per tal d’entendre els fenòmens que influencien la degradació de les cel·les durant la seva vida. L’experiment d’envelliment és una comparació entre un sistema de balanceig passiu (Passive Balancing, en anglès) i un de balanceig actiu. Per això s’escullen dues bateries idèntiques, però gestionades diferentment per dos sistemes de gestió diferents. Al final de l’assaig, les bateries es desmunten i s’analitza cada cel·la de forma individual per tal de determinar-ne els seus paràmetres i el seu envelliment. La principal contribució d’aquest treball es el demostrar els efectes del balanceig actiu , sobretot en bateries amb una càrrega elevada. El treball demostra que el balanceig actiu millor gla capacitat de la bateria i la vida útil. El treball també mostra com la variació dels paràmetres de les cel·les es pot fer visible durant la seva operació. També presenta nous mètodes de diagnosi i càlcul d’aquests paràmetres. L’eficiència energètica de les bateries no es pot augmentar degut al consum propi i les pèrdues del sistema de balanceig actiu basat en electrònica de potencia. Si que augmenta l’eficiència global de la bateria, ja que augmenta la seva capacitat i la vida útil. El treball també mostra que en bateries sotmeses a baixa càrrega, el balanceig actiu no aporta cap avantatge respecte el balanceig passiu. Fins i tot en algunes situacions, els efectes del balanceig actiu són negatius. En aquestes aplicacions, es recomana l’ús d’un sistema de balanceig passiu. Els resultats obtinguts durant l’assaig de la bateria queden reforçats quan es fa l’anàlisi de cada cel·la de forma individual. Al final del treball, es resumeixen tots els resultats a més de proporcionar suggereixes per la optimització així com possibles línies de futures investigacionsPostprint (published version

Das Wie und Warum mathematischer Wirkung

Mathematik scheint den natürlichen Formalismus zur Beschreibung und Berechnung physikalischer Prozesse und Gesetzmäßigkeiten zu liefern. Umgekehrt haben physikalische Fragestellungen die Entwicklung der Mathematik angeregt und teilweise ihre Richtung bestimmt, und eigentlich gibt es keine scharfe Grenze zwischen Mathematik und Physik. Eine sinnvolle Einteilung bezieht sich eher auf die Motivation als auf die Untersuchungsgegenstände der Mathematik: Forschung wird betrieben, um mathematische Strukturen zu verstehen oder ist durch naturwissenschaftliche oder technisch‐industrielle Anwendungen motiviert

Feasibility of radiomic feature harmonization for pooling of [18F]FET or [18F]GE-180 PET images of gliomas

Introduction: Large datasets are required to ensure reliable non-invasive glioma assessment with radiomics-based machine learning methods. This can often only be achieved by pooling images from different centers. Moreover, trained models should perform with high accuracy when applied to data from different centers. In this study, the impact of reconstruction settings and segmentation methods on radiomic features derived from amino acid and TSPO PET images of glioma patients was examined. Additionally, the ability to model and thus reduce feature differences was investigated.Methods: [(18)FJFET and [(18)FJGE-180 PET data were acquired from 19 glioma patients. For each acquisition, 10 reconstruction settings and 9 segmentation methods were included to emulate multicentric data. Statistical robustness measures were calculated before and after ComBat harmonization. Differences between features due to setting variations were assessed using Friedman test, coefficient of variation (CV) and inter-rater reliability measures, including intraclass and Spearman's rank correlation coefficients and Fleiss' Kappa.Results: According to Friedman analyses, most features (>60%) showed significant differences. Yet, CV and interrater reliability measures indicated higher robustness. ComBat resulted in almost complete harmonization (>87%) according to Friedman test and little to no improvement according to CV and inter-rater reliability measures. [(18)FJGE-180 features were more sensitive to reconstruction settings than [(18)FJFET features.Conclusions: According to Friedman test, feature distributions could be successfully aligned using ComBat. However, depending on settings, changes in patient ranks were observed for some features and could not be eliminated by harmo-nization. Thus, for clinical utilization it is recommended to exclude affected features

Extensive alterations of the whole-blood transcriptome are associated with body mass index: results of an mRNA profiling study involving two large population-based cohorts

Background: Obesity, defined as pathologically increased body mass index (BMI),is strongly related to an increased risk for numerous common cardiovascular and metabolic diseases. It is particularly associated with insulin resistance, hyperglycemia, and systemic oxidative stress and represents the most important risk factor for type 2 diabetes (T2D). However, the pathophysiological mechanisms underlying these associations are still not completely understood. Therefore, in order to identify potentially disease-relevant BMI-associated gene expression signatures, a transcriptome-wide association study (TWAS) on BMI was performed. Methods: Whole-blood mRNA levels determined by array-based transcriptional profiling were correlated with BMI in two large independent population-based cohort studies (KORA F4 and SHIP-TREND) comprising a total of 1977 individuals. Results: Extensive alterations of the whole-blood transcriptome were associated with BMI: More than 3500 transcripts exhibited significant positive or negative BMI-correlation. Three major whole-blood gene expression signatures associated with increased BMI were identified. The three signatures suggested: i) a ratio shift from mature erythrocytes towards reticulocytes, ii) decreased expression of several genes essentially involved in the transmission and amplification of the insulin signal, and iii) reduced expression of several key genes involved in the defence against reactive oxygen species (ROS). Conclusions: Whereas the first signature confirms published results, the other two provide possible mechanistic explanations for well-known epidemiological findings under conditions of increased BMI, namely attenuated insulin signaling and increased oxidative stress. The putatively causative BMI-dependent down-regulation of the expression of numerous genes on the mRNA level represents a novel finding. BMI-associated negative transcriptional regulation of insulin signaling and oxidative stress management provide new insights into the pathogenesis of metabolic syndrome and T2D

Comparing the MRI-based Goutallier Classification to an experimental quantitative MR spectroscopic fat measurement of the supraspinatus muscle

Background The Goutallier Classification is a semi quantitative classification system to determine the amount of fatty degeneration in rotator cuff muscles. Although initially proposed for axial computer tomography scans it is currently applied to magnet-resonance-imaging-scans. The role for its clinical use is controversial, as the reliability of the classification has been shown to be inconsistent. The purpose of this study was to compare the semi quantitative MRI-based Goutallier Classification applied by 5 different raters to experimental MR spectroscopic quantitative fat measurement in order to determine the correlation between this classification system and the true extent of fatty degeneration shown by spectroscopy. Methods MRI-scans of 42 patients with rotator cuff tears were examined by 5 shoulder surgeons and were graduated according to the MRI-based Goutallier Classification proposed by Fuchs et al. Additionally the fat/water ratio was measured with MR spectroscopy using the experimental SPLASH technique. The semi quantitative grading according to the Goutallier Classification was statistically correlated with the quantitative measured fat/water ratio using Spearman’s rank correlation. Results Statistical analysis of the data revealed only fair correlation of the Goutallier Classification system and the quantitative fat/water ratio with R = 0.35 (p < 0.05). By dichotomizing the scale the correlation was 0.72. The interobserver and intraobserver reliabilities were substantial with R = 0.62 and R = 0.74 (p < 0.01). Conclusion The correlation between the semi quantitative MRI based Goutallier Classification system and MR spectroscopic fat measurement is weak. As an adequate estimation of fatty degeneration based on standard MRI may not be possible, quantitative methods need to be considered in order to increase diagnostic safety and thus provide patients with ideal care in regard to the amount of fatty degeneration. Spectroscopic MR measurement may increase the accuracy of the Goutallier classification and thus improve the prediction of clinical results after rotator cuff repair. However, these techniques are currently only available in an experimental setting

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Abdominal aortic aneurysm is associated with a variant in low-density lipoprotein receptor-related protein 1

Abdominal aortic aneurysm (AAA) is a common cause of morbidity and mortality and has a significant heritability. We carried out a genome-wide association discovery study of 1866 patients with AAA and 5435 controls and replication of promising signals (lead SNP with a p value &lt; 1 × 10-5) in 2871 additional cases and 32,687 controls and performed further follow-up in 1491 AAA and 11,060 controls. In the discovery study, nine loci demonstrated association with AAA (p &lt; 1 × 10-5). In the replication sample, the lead SNP at one of these loci, rs1466535, located within intron 1 of low-density-lipoprotein receptor-related protein 1 (LRP1) demonstrated significant association (p = 0.0042). We confirmed the association of rs1466535 and AAA in our follow-up study (p = 0.035). In a combined analysis (6228 AAA and 49182 controls), rs1466535 had a consistent effect size and direction in all sample sets (combined p = 4.52 × 10-10, odds ratio 1.15 [1.10-1.21]). No associations were seen for either rs1466535 or the 12q13.3 locus in independent association studies of coronary artery disease, blood pressure, diabetes, or hyperlipidaemia, suggesting that this locus is specific to AAA. Gene-expression studies demonstrated a trend toward increased LRP1 expression for the rs1466535 CC genotype in arterial tissues; there was a significant (p = 0.029) 1.19-fold (1.04-1.36) increase in LRP1 expression in CC homozygotes compared to TT homozygotes in aortic adventitia. Functional studies demonstrated that rs1466535 might alter a SREBP-1 binding site and influence enhancer activity at the locus. In conclusion, this study has identified a biologically plausible genetic variant associated specifically with AAA, and we suggest that this variant has a possible functional role in LRP1 expression

Causal effect of plasminogen activator inhibitor type 1 on coronary heart disease

Background--Plasminogen activator inhibitor type 1 (PAI-1) plays an essential role in the fibrinolysis system and thrombosis. Population studies have reported that blood PAI-1 levels are associated with increased risk of coronary heart disease (CHD). However, it is unclear whether the association reflects a causal influence of PAI-1 on CHD risk. Methods and Results--To evaluate the association between PAI-1 and CHD, we applied a 3-step strategy. First, we investigated the observational association between PAI-1 and CHD incidence using a systematic review based on a literature search for PAI-1 and CHD studies. Second, we explored the causal association between PAI-1 and CHD using a Mendelian randomization approach using summary statistics from large genome-wide association studies. Finally, we explored the causal effect of PAI-1 on cardiovascular risk factors including metabolic and subclinical atherosclerosis measures. In the systematic meta-analysis, the highest quantile of blood PAI-1 level was associated with higher CHD risk comparing with the lowest quantile (odds ratio=2.17; 95% CI: 1.53, 3.07) in an age- and sex-adjusted model. The effect size was reduced in studies using a multivariable-adjusted model (odds ratio=1.46; 95% CI: 1.13, 1.88). The Mendelian randomization analyses suggested a causal effect of increased PAI-1 level on CHD risk (odds ratio=1.22 per unit increase of log-transformed PAI-1; 95% CI: 1.01, 1.47). In addition, we also detected a causal effect of PAI-1 on elevating blood glucose and high-density lipoprotein cholesterol. Conclusions--Our study indicates a causal effect of elevated PAI-1 level on CHD risk, which may be mediated by glucose dysfunction

Genetic associations at 53 loci highlight cell types and biological pathways relevant for kidney function.

Reduced glomerular filtration rate defines chronic kidney disease and is associated with cardiovascular and all-cause mortality. We conducted a meta-analysis of genome-wide association studies for estimated glomerular filtration rate (eGFR), combining data across 133,413 individuals with replication in up to 42,166 individuals. We identify 24 new and confirm 29 previously identified loci. Of these 53 loci, 19 associate with eGFR among individuals with diabetes. Using bioinformatics, we show that identified genes at eGFR loci are enriched for expression in kidney tissues and in pathways relevant for kidney development and transmembrane transporter activity, kidney structure, and regulation of glucose metabolism. Chromatin state mapping and DNase I hypersensitivity analyses across adult tissues demonstrate preferential mapping of associated variants to regulatory regions in kidney but not extra-renal tissues. These findings suggest that genetic determinants of eGFR are mediated largely through direct effects within the kidney and highlight important cell types and biological pathways