Bidirectional Charging (Vehicle-to-Home) in Home Energy Management Systems: Exploring Potentials with a Simulation Tool

The home will become the most important link between heat, electricity and mobility. For instance, the concept of Vehicle-to-Home (V2H) allows to use the average long parking times of electric vehicles for energy management applications in the household. In this study, we focus on developing a simulation model in the Home Energy Management System (HEMS) to explore the impact of bidirectional charging on household energy supply. Bidirectional charging allows electric vehicles not only to take energy but also to feed energy back to supply other consumers. The study addresses the following research question: What is the potential for increasing self-sufficiency through bidirectional charging in a modern single-family house with HEMS assets? First of all, bidirectional charging was researched in initial pilot projects, and the findings were used to validate the results. Furthermore, load profiles for household loads, heat loads (heat pumps) and production profiles (photovoltaics) were collected. Based on the findings from the literature, a simulation model was developed that considers the dynamic interactions between the electric vehicle and the system components in the household. Different scenarios of bidirectional charging could be simulated and compared e.g. with a unidirectional system. In addition, different parameters could be adapted and analyzed through a sensitivity analysis. Parameters of photovoltaic power, orientation of the photovoltaic system, capacity of vehicle battery and home storage, as well as daily consumption by kilometers driven were varied. The results of the simulations show that bidirectional charging has the potential to increase the self-sufficiency of renewable energy (in this case photovoltaics) in the household, to reduce electricity costs and indirectly to reduce the load from the energy grid. It is important to say that the potential strongly depends on individual user behavior, photovoltaic power and the presence of the vehicle on site. This study contributes to the scientific literature by presenting a simulation model for bidirectional charging in HEMS. The results provide important insights for households and the simulation model can be a decision support tool for the choice and sizing of system components in the HEMS. In addition, the study provides input for further research and development in the field of electromobility and home energy management systems

Influence of an acetate- and a lactate-based balanced infusion solution on acid base physiology and hemodynamics: an observational pilot study

Background: The current pilot study compares the impact of an intravenous infusion of Ringer's lactate to an acetate-based solution with regard to acid-base balance. The study design included the variables of the Stewart approach and focused on the effective strong ion difference. Because adverse hemodynamic effects have been reported when using acetate buffered solutions in hemodialysis, hemodynamics were also evaluated. Methods: Twenty-four women who had undergone abdominal gynecologic surgery and who had received either Ringer's lactate (Strong Ion Difference 28 mmol/L; n = 12) or an acetate-based solution (Strong Ion Difference 36.8 mmol/L; n = 12) according to an established clinical protocol and its precursor were included in the investigation. After induction of general anesthesia, a set of acid-base variables, hemodynamic values and serum electrolytes was measured three times during the next 120 minutes. Results: Patients received a mean dose of 4,054 +/- 450 ml of either one or the other of the solutions. In terms of mean arterial blood pressure and norepinephrine requirements there were no differences to observe between the study groups. pH and serum HCO3- concentration decreased slightly but significantly only with Ringer's lactate. In addition, the acetate-based solution kept the plasma effective strong ion difference more stable than Ringer's lactate. Conclusions: Both of the solutions provided hemodynamic stability. Concerning consistency of acid base parameters none of the solutions seemed to be inferior, either. Whether the slight advantages observed for the acetate-buffered solution in terms of stability of pH and plasma HCO3- are clinically relevant, needs to be investigated in a larger randomized controlled trial

Vignettes in research and teaching: Review of research activities and potential applications

Verschiedene Einsatzmöglichkeiten von fachdidaktischen Unterrichtsvignetten in der empirischen Bildungsforschung sowie in der Lehrerinnen- und Lehrerbildung werden vorgestellt. Dabei wird auf die Verwendung von Unterrichtsvignetten als Testaufgaben sowie als Materialien zur Ausbildung professioneller Kompetenzen von (angehenden) Lehrkräften fokussiert. Nach der Darstellung der Konstruktionsprinzipien sowie der Präsentationsformate für Unterrichtsvignetten werden methodische Implikationen zur statistischen Auswertung von vignettenbasierten Testverfahren diskutiert. (DIPF/Orig.)The article summarizes potential applications of vignettes in educational research and teacher education. It focuses on both the use of vignettes for assessing professional skills like pedagogical content knowledge and vignettes as a teaching material. After the presentation of approaches to generating vignettes, methodical implications for statistical analyses of vignettebased tests are discussed

Fachdidaktische Unterrichtsvignetten in Forschung und Lehre: Überblick über Forschungsarbeiten und Einsatzmöglichkeiten

Verschiedene Einsatzmöglichkeiten von fachdidaktischen Unterrichtsvignetten in der empirischen Bildungsforschung sowie in der Lehrerinnen- und Lehrerbildung werden vorgestellt. Dabei wird auf die Verwendung von Unterrichtsvignetten als Testaufgaben sowie als Materialien zur Ausbildung professioneller Kompetenzen von (angehenden) Lehrkräften fokussiert. Nach der Darstellung der Konstruktionsprinzipien sowie der Präsentationsformate für Unterrichtsvignetten werden methodische Implikationen zur statistischen Auswertung von vignettenbasierten Testverfahren diskutiert.&nbsp

Comparison of 6 % hydroxyethyl starch and 5 % albumin for volume replacement therapy in patients undergoing cystectomy (CHART): study protocol for a randomized controlled trial

Background The use of artificial colloids is currently controversial, especially in Central Europe Several studies demonstrated a worse outcome in intensive care unit patients with the use of hydroxyethyl starch. This recently even led to a drug warning about use of hydroxyethyl starch products in patients admitted to the intensive care unit. The data on hydroxyethyl starch in non–critically ill patients are insufficient to support perioperative use. Methods/Design We are conducting a single-center, open-label, randomized, comparative trial with two parallel patient groups to compare human albumin 5 % (test drug) with hydroxyethyl starch 6 % 130/0.4 (comparator). The primary endpoint is cystatin C ratio, calculated as the ratio of the cystatin value at day 90 after surgery relative to the preoperative value. Secondary objectives are inter alia the evaluation of the influence of human albumin and hydroxyethyl starch on further laboratory chemical and clinical parameters, glycocalyx shedding, intensive care unit and hospital stay and acute kidney injury as defined by RIFLE criteria (risk of renal dysfunction, injury to the kidney, failure of kidney function, loss of kidney function, and end-stage kidney disease) criteria. Discussion There is a general lack of evidence on the relative safety and effects of hydroxyethyl starch compared with human albumin for volume replacement in a perioperative setting. Previously conducted studies of surgical patients in which researchers have compared different hydroxyethyl starch products included too few patients to properly evaluate clinical important outcomes such as renal function. In the present study in a high-risk patient population undergoing a major surgical intervention, we will determine if perioperative fluid replacement with human albumin 5 % will have a long-term advantage over a third-generation hydroxyethyl starch 130/0.4 on the progression of renal dysfunction until 90 days after surgery

Relationierung von Theorie und Praxis im Zusammenhang mit unterrichtlichem Handeln: Befunde aus der zweiten Phase der Lehrerinnen und Lehrerbildung

Das Theorie-Praxis-Verhältnis spielt eine zentrale Rolle in der Lehrerinnen und Lehrerbildung. Ausgehend davon, dass angehende Lehrkräfte wissenschaftliche Erkenntnisse und schulpraktische Erfahrungen in Beziehung setzen sollen, untersucht die vorliegende Studie, inwiefern diese Relationierung Inhalt von Seminaren im Vorbereitungsdienst ist und mit dem Unterricht der angehenden Lehrkräfte korreliert. Die Daten von 541 Befragten zeigen Unterschiede in der wahrgenommenen Relationierung von Theorie und Praxis. Personen, die eine stärkere Relationierung in Seminaren berichteten, weisen höhere Ausprägungen in Qualitätsmerkmalen des Unterrichts auf. Die Befunde untermauern die Relevanz, im Vorbereitungsdienst schulpraktische Erfahrungen mit wissenschaftlichen Perspektiven zu verbinden.&nbsp

The intravascular volume effect of Ringer's lactate is below 20%: a prospective study in humans

Introduction: Isotonic crystalloids play a central role in perioperative fluid management. Isooncotic preparations of colloids (for example, human albumin or hydroxyethyl starch) remain nearly completely intravascular when infused to compensate for acute blood losses. Recent data were interpreted to indicate a comparable intravascular volume effect for crystalloids, challenging the occasionally suggested advantage of using colloids to treat hypovolemia. General physiological knowledge and clinical experience, however, suggest otherwise. Methods: In a prospective study, double-tracer blood volume measurements were performed before and after intended normovolemic hemodilution in ten female adults, simultaneously substituting the three-fold amount of withdrawn blood with Ringer's lactate. Any originated deficits were substituted with half the volume of 20% human albumin, followed by a further assessment of blood volume. To assess significance between the measurements, repeated measures analysis of variance (ANOVA) according to Fisher were performed. If significant results were shown, paired t tests (according to Student) for the singular measurements were taken. P < 0.05 was considered to be significant. Results: A total of 1,097 +/- 285 ml of whole blood were withdrawn (641 +/- 155 ml/m2 body surface area) and simultaneously replaced by 3,430 +/- 806 ml of Ringer's lactate. All patients showed a significant decrease in blood volume after hemodilution (-459 +/- 185 ml; P < 0.05) that did not involve relevant hemodynamical changes, and a significant increase in interstitial water content (+ 2,157 +/- 606 ml; P < 0.05). The volume effect of Ringer's lactate was 17 +/- 10%. The infusion of 245 +/- 64 ml of 20% human albumin in this situation restored blood volume back to baseline values, the volume effect being 184 +/- 63%. Conclusions: Substitution of isolated intravascular deficits in cardiopulmonary healthy adults with the three-fold amount of Ringer's lactate impedes maintenance of intravascular normovolemia. The main side effect was an impressive interstitial fluid accumulation, which was partly restored by the intravenous infusion of 20% human albumin. We recommend to substitute the five-fold amount of crystalloids or to use an isooncotic preparation in the face of acute bleeding in patients where edema prevention might be advantageous

Relationship building between theory and practice in the context of first teaching experiences: Findings from the induction phase of teacher preparation

Das Theorie-Praxis-Verhältnis spielt eine zentrale Rolle in der Lehrerinnen und Lehrerbildung. Ausgehend davon, dass angehende Lehrkräfte wissenschaftliche Erkenntnisse und schulpraktische Erfahrungen in Beziehung setzen sollen, untersucht die vorliegende Studie, inwiefern diese Relationierung Inhalt von Seminaren im Vorbereitungsdienst ist und mit dem Unterricht der angehenden Lehrkräfte korreliert. Die Daten von 541 Befragten zeigen Unterschiede in der wahrgenommenen Relationierung von Theorie und Praxis. Personen, die eine stärkere Relationierung in Seminaren berichteten, weisen höhere Ausprägungen in Qualitätsmerkmalen des Unterrichts auf. Die Befunde untermauern die Relevanz, im Vorbereitungsdienst schulpraktische Erfahrungen mit wissenschaftlichen Perspektiven zu verbinden. (DIPF/Orig.)The relationship between theory and practice is considered central in teacher education. Based on the assumption that teacher candidates should relate scientific knowledge and field-based experiences, this study investigates in which way such relationship building is addressed in courses that accompany practical induction and to what extent it correlates with the self-perceived quality of instruction. Data from 541 teacher candidates indicate substantial differences concerning relationship building that are statistically and positively related to differences in the quality of instruction. The results underline the importance of connecting field experiences with scientific perspectives during the phase of practical induction

Hydroxyethyl starch 130/0.4 and its impact on perioperative outcome: a propensity score matched controlled observation study

BACKGROUND Adverse effects of hydroxyethyl starches (HESs) have been verified in patients suffering from sepsis or kidney disease, but not in surgical patients at large. The investigation aimed to determine whether the use of HES 130/0.4 was associated with the incidence of acute postinterventional adverse events compared to Ringer's acetate alone in a perioperative setting. METHODS This propensity score matched, controlled observational study was performed in a single-centre university hospital. The perioperative data of 9085 patients were analyzed. Group matching was based on 13 categories including demographic data, type of procedure, and 5 preexisting comorbidities. Duration of procedure and intraoperative transfusion requirements were integrated in the matching process to reduce selection and indication bias. The primary outcome was incidence of postoperative kidney failure. Secondary outcomes were in-hospital mortality, fluid requirements, blood loss, hemodynamic stability, and the need for postoperative intensive care unit (ICU) treatment. RESULTS The administration of HES 130/0.4 was not associated with an increased frequency of postoperative kidney failure. In-hospital mortality (Ringer's acetate: 2.58%; HES 130/0.4: 2.68%) and the need for ICU care (Ringer's acetate: 30.5%; HES 130/0.4: 34.3%) did not differ significantly between groups. Significant intergroup differences were observed for mean blood loss (Ringer's acetate: 406 ± 821 mL; HES 130/0.4: 867 ± 1275 mL; P < .001) and median length of hospital stay (Ringer's acetate: 10.5 (5/17) days; HES 130/0.4: 12.0 (8/19) days; P < .001). CONCLUSIONS An association between intraoperative HES therapy and postoperative kidney failure was not observed in a mixed cohort of elective surgical patients. In addition, HES 130/0.4 was not associated with an increased morbidity or the need for ICU therapy in this propensity score matched study