Numerical and experimental investigation of a semi-active vibration control system by means of vibration energy conversion

A vibration control concept based on vibration energy conversion and storage with respect to a serial-stiffness-switch system (4S) has previously been proposed. Here, we first present a rotational electromagnetic serial-stiffness-switch system as a novel practical vibration control system for experimental validation of the concept and, furthermore, an improved control strategy for higher vibration suppression performance is also proposed. The system consists of two spring-switch elements in series, where a parallel switch can block a spring. As an alternating mechanical switch, the experimental system uses two electromagnets with a shared armature. By connecting the armature to the rotating load or the base, the electromagnets decide which of the two spiral springs is blocked, while the other is active. A switching law based on the rotation velocity of the payload is used. Modelling and building of the experimental system were carried out. The corresponding experiment and simulation were executed and they matched well. These results prove that our serial-stiffness-switch system is capable of converting vibration energy and realizing vibration reduction under a forced harmonic disturbance. The effects of disturbance frequency, disturbance amplitude and sampling frequency on the system performance are shown as well. A position feedback control-based switching law is further put forward and experimentally verified to improve the repositioning accuracy of the disturbed system

Schwingungsreduktion und Reluktanzmaschinen

Die vorliegende Dissertation ist eine theoretische Arbeit mit mehreren Schwerpunkten. Einleitend ist gezeigt, wie aus der mechanischen Leistung die Konzepte von Schwingungsisolation und Schwingungstilgung folgen und welchen Einfluss die Systemgrenzen haben. Das Grundlagenkapitel befasst sich mit der Leistungswandlung und Energiespeicherung in Reluktanzmaschinen. Dabei ist auch die magnetische Energie in polarisierten Systemen betrachtet und in der Fluss-Durchflutung-Ebene dargestellt. Die Funktion der Reluktanzmaschine ist anhand von Kraftkennlinien erklärt, die aus den integralen Kraftkennfeldern folgen. Das Entwicklungskapitel beschreibt eine iterative Methode um Steuersignale zu berechnen, mit denen die Lautstärke von Reluktanzmaschinen geringer ist. Dafür wird der Verlauf des magnetischen Flusses über der Position des Rotors nach diversen Kriterien schrittweise verändert. Als Ergebnis liegen Kommutierungstabellen vor, die auf minimale Akustik, minimale Drehmomentwelligkeit oder maximale Energieeffizienz optimiert sind. Das Forschungskapitel beginnt mit der Frage, wie viele Phasen eine Reluktanzmaschine haben muss. Ein inverser Entwurf zeigt, dass zwei Phasen genügen, um an jeder Position des Rotors in beide Richtungen der Bewegung eine Kraft erzeugen zu können. Dabei wird gezielt auch die Gegeninduktivität genutzt und mit bipolarem Strom gearbeitet. Eine Analyse der erhöhten Blindleistung und die Bauform als Transversalflussmaschine schließen dieses Kapitel ab. Der Ausblick enthält neben dem kurzen Fazit auch allgemeine Empfehlungen zur weiteren Forschung für Reluktanzmaschinen. Ein großes Potenzial liegt in der Optimierung von Forschung allgemein und den daran beteiligten Prozessen, vor allem der Software.This dissertation is a theoretical work on multiple subjects. Starting with the mechanical power, the concepts of vibration isolation and vibration absorption are derived and the influence of the systems boundary choice is indicated. The basics chapter deals with power conversion and energy storage in reluctance machines. Visualization of magnetic energy is done in the flux-mmf-plane, also detailed for polarized magnetic systems. The operation of reluctance machines is explained using force characteristics of individual phases. The development chapter describes an iterative method to calculate a control signal which reduces the noise of reluctance machines. Therefore, the magnetic flux as a function of the rotor position is iteratively adjusted through various criteria. The results are commutation tables, which are optimized for minimal acoustic emissions, minimal torque ripple, or high efficiency. The research chapter builds on the question, how many phases a reluctance machine requires. An inverse design reveals that two phases are sufficient to produce a force in both directions of movement and at any position of the rotor. Therefore, a bipolar current utilizes the mutual inductance too. An analysis of increased reactive power and a construction as transversal flux machine conclude this chapter. At the end a short summary and recommendations for future research on reluctance machines are given. A large potential lies in the optimization of research overall and the involved processes, especially the software

Factors determining airlines' costs for climate protecting market-based measures

This paper investigates the factors influencing airline’s costs for climate protecting market-based measures. It is based on selected results of the interdisciplinary research project AviClim (Including Aviation in International Protocols for Climate Protection). AviClim has investigated how to limit aviation’s full climate impact best from an environmental and economic point of view. In this research project, both long-lived CO2 and short-lived non-CO2 effects of aviation have been addressed simultaneously and climate protecting scenarios for aviation in the timeframe 2010-2030 have been developed. On this basis, the factors determining aviation’s costs for climate protecting measures have been analysed. Results indicate that the choice of the market-based measure, it’s regional scope, the metric chosen for the translation of the non-CO2 impacts into equivalent CO2 and the prices for equivalent CO2 are important factors for airline’s costs. An analysis for single flights reveals remarkable differences in specific emissions (tons CO2 equivalent/flight kilometre). An investigation for groups of airlines differentiated by business model and country of origin indicates that the world regions served by the airlines, the business model, the length and the emission characteristics of the flights are further important factors for the costs of the regulating measure

Climate-Optimised Intermediate Stop Operations: Mitigation Potential and Differences from Fuel-Optimised Configuration

Saving fuel by splitting a flight mission with an intermediate stop for refuelling is described by the concept of intermediate stop operations. This can also be beneficial to the climate impact of aviation, if the flight level and intermediate stop airport are selected accordingly. This study aims to estimate the mitigation potential of an implementation of climate-optimised intermediate stop operations for European long-haul flights and compare it to fuel-optimal operations. For this purpose, fuel consumption and emissions are simulated along four-dimensional trajectories for the selected annual flight plan, and their average temperature response is calculated. A comparison between the reference case and climate-optimised as well as fuel-optimised scenarios shows a significant climate mitigation potential and reveals a shift of trajectories to lower latitudes and altitudes. However, increased flight times and fuel consumption limit implementation from stakeholders’ perspectives

Migration background and juvenile mental health: a descriptive retrospective analysis of diagnostic rates of psychiatric disorders in young people

Introduction: This article presents diagnostic rates for specific mental disorders in a German pediatric inpatient population over a period of 20 years with respect to migration background and socioeconomic status (SES).Methods: Diagnostic data were obtained over a period of 20 years from 8,904 patients who visited a child and adolescent psychiatry mental health service in Germany. Data from 5,985 diagnosed patients (ICD-9 and ICD-10 criteria) were included with respect to gender, migration background, and SES.Results: Migration- and gender-specific effects were found for both periods of assessment. The group of boys with a migration background showed significantly higher rates of reactions to severe stress, adjustment disorders, and posttraumatic stress disorder compared to their male, non-migrant counterparts. Conversely, boys without a migration background showed a significantly higher percentage rate of hyperkinetic disorders than male migrants. Similar results were found for female migrants in the latter assessment period (ICD-10). In addition, female migrants showed lower rates of emotional disorders whose onset occurs in childhood compared to their non-migrant counterparts.Conclusions: Data from this investigation provide preliminary evidence that the prevalence of various psychiatric disorders in children and adolescents is influenced by migration background and SES

Электрооборудование тепловой насосной станции

В данной работе выполнен расчет электроснабжения тепловой насосной станции №2 города Саяногорска. В работе так же рассмотрен механизм управления сетевым насосом при помощи преобразователя частоты с целью снижения потребляемой электрической энергии.In this paper, the power supply to the heat pump station No. 2 in Sayanogorsk has been calculated. In work the mechanism of management of the network pump by means of the frequency converter with the purpose of decrease in consumed electric energy is also considered

Murine and human pluripotent stem cell-derived cardiac bodies form contractile myocardial tissue in vitro

AimsWe explored the use of highly purified murine and human pluripotent stem cell (PSC)-derived cardiomyocytes (CMs) to generate functional bioartificial cardiac tissue (BCT) and investigated the role of fibroblasts, ascorbic acid (AA), and mechanical stimuli on tissue formation, maturation, and functionality.Methods and resultsMurine and human embryonic/induced PSC-derived CMs were genetically enriched to generate three-dimensional CM aggregates, termed cardiac bodies (CBs). Addressing the critical limitation of major CM loss after single-cell dissociation, non-dissociated CBs were used for BCT generation, which resulted in a structurally and functionally homogenous syncytium. Continuous in situ characterization of BCTs, for 21 days, revealed that three critical factors cooperatively improve BCT formation and function: both (i) addition of fibroblasts and (ii) ascorbic acid supplementation support extracellular matrix remodelling and CB fusion, and (iii) increasing static stretch supports sarcomere alignment and CM coupling. All factors together considerably enhanced the contractility of murine and human BCTs, leading to a so far unparalleled active tension of 4.4 mN/mm2 in human BCTs using optimized conditions. Finally, advanced protocols were implemented for the generation of human PSC-derived cardiac tissue using a defined animal-free matrix composition.ConclusionBCT with contractile forces comparable with native myocardium can be generated from enriched, PSC-derived CMs, based on a novel concept of tissue formation from non-dissociated cardiac cell aggregates. In combination with the successful generation of tissue using a defined animal-free matrix, this represents a major step towards clinical applicability of stem cell-based heart tissue for myocardial repair. © 2013 The Author

Decision parameters of an MRV scheme for integrating non-CO2 aviation effects into EU ETS

Although about two-thirds of aviation's climate impacts are caused by non-CO2 effects, such as ozone production or contrail cirrus formation, these effects are not yet considered in existing and currently planned policy instruments (e.g. EU ETS or CORSIA). Due to their climatological relevance, however, various economic concepts have been proposed recently to internalise nonCO2 effects. Most of these approaches are based on the principle of equivalent CO2 emissions (CO2e), a way of unitizing the impact of all climate agents. Several calculation methods for CO2 equivalents are in principle available, which differ in the degree of detail and are subject to uncertainties related to atmospheric science. There are a quite a few key decision parameters for policy makers for setting up a monitoring, reporting, and verification (MRV) scheme for non-CO2 effects. The aim of this study is therefore to analyze and discuss the most important decision parameters for the integration of non-CO2 aviation effects into EU ETS