New semi-active vibration control with Serial-Stiffness-Switch-System based on vibration energy harvesting

Diese Dissertation untersucht eine neuartige semi-aktive Schwingungsteuerung mit einem seriellen-Steifigkeit-Schalter-System (4S) basierend auf der Speicherung von Schwingungsenergie. Auf Basis der Schwingungsreduktionsanalyse für ein passives und ein semi-aktives Schaltsystem werden Probleme vorhandener Schwingungsteuerungssystemen aufgezeigt und durch das 4S Konzept gelöst. Um seine Leistungsfähigkeit zu untersuchen, wird zunächst 4S im offenen Regelkreis analysiert und die äquivalente Steifigkeit und Eigenfrequenz des Schaltsystems abgeleitet. Es folgt die Analyse für 4S im geschlossenen Regelkreis. Zur Schwingungsreduzierung wird ein Geschwindigkeits-Nulldurchgangs Schaltgesetz verwendet, das auf der Speicherung von Schwingungsenergie basiert. Dies wird unter einer harmonischen Störung numerisch validiert. Anschließend werden Grenzen der Energiespeicherung analysiert. Es folgt eine experimentelle Validierung dieser neuartigen Strategie zur Schwingungssteuerung vorgestellt und ein drehender Prüfstand entwickelt. Der Prüfstand verwendet zwei ringförmig angeordnete Elektromagnetplatten zusammen mit einer Ankerwelle als zwei mechanische Schalter, um die Verbindung oder Trennung von zwei Spiralfedern mit einem Lastträgheitsmoment zu erreichen. Die Speicherung von Schwingungsenergie und die Schwingungsreduktion werden auf diesem Versuchssystem getestet. Neben einer harmonischen Störung wird auch eine Anfangsgeschwindigkeit ungleich Null berücksichtigt. Um in diesem Fall die Schwingungsreduktion zu verbessern, wird ein neues Schaltgesetz vorgeschlagen. Mit Hilfe der Phasenebene wird das transiente und stationäre Ratterverhalten von 4S analysiert. Das Schaltgesetz ermöglicht eine schnelle Umwandlung der anfänglichen kinetischen Energie, die in beiden Federn zu gleichen Teilen gespeichert wird. Dies ist numerisch und experimentell validiert. Zusätzlich wird einer harmonischen Störung an dem neuen Schaltgesetz getestet, das ein besseres Positionierverhalten als das Geschwindigkeits-Nulldurchgangs Schaltgesetz aufweist. Schließlich wird 4S zur Schockisolierung eingesetzt. Die maximale Reduzierung des Überschwingens des Wegs beim Schock und die Reduktion der Restschwingungen nach dem Schock werden numerisch validiert. Darüber hinaus wird auch der Einfluss verschiedener Designparameter von 4S auf das Isolationsverhalten untersucht.This dissertation investigates a novel semi-active vibration control with Serial-Stiffness-Switch-System (4S) based on vibration energy harvesting. On the basis of the vibration reduction performance analysis for a passive and a semi-active switching system, the problem in the present vibration control systems is stated and 4S concept is consequently put forward. In order to examine its performance, 4S in open loop control is analyzed firstly and the equivalent stiffness and natural frequency of the switching system are derived. Following is the analysis for 4S in closed loop control. A velocity zero-crossing switching law based on vibration energy harvesting is used for vibration reduction. This is numerically validated under a harmonic disturbance. Afterwards, vibration energy harvesting limit is analyzed. An experimental validation on this novel vibration control strategy is then presented and a rotational test rig is developed. The test rig uses two ring-arranged electromagnet-plates together with an armature-shaft as two mechanical switches to achieve the connection or disconnection of two spiral springs to or from a primary plate. The vibration energy harvesting and vibration reduction performance of 4S are tested on this experimental system. Apart from a harmonic disturbance, a nonzero initial velocity vibration is also considered. To improve vibration reduction performance in this case, a new switching law is proposed. By means of phase plane, the transient and steady chattering response of 4S are analyzed. The switching law enables a fast transformation of initial vibration energy into potential energy equally stored in two springs. This is numerically and experimentally validated. Additionally, a harmonic disturbance is also exerted on the new switching law. The results show that 4S has a better positioning performance than that for the velocity zero-crossing switching law. Finally, 4S is further applied for shock isolation. The maximum displacement response reduction during shock and the residual vibration suppression after shock are numerically validated. Moreover, the effect of several design parameters of 4S on the shock isolation performance is investigated as well

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

Design and baseline characteristics of the finerenone in reducing cardiovascular mortality and morbidity in diabetic kidney disease trial

Background: Among people with diabetes, those with kidney disease have exceptionally high rates of cardiovascular (CV) morbidity and mortality and progression of their underlying kidney disease. Finerenone is a novel, nonsteroidal, selective mineralocorticoid receptor antagonist that has shown to reduce albuminuria in type 2 diabetes (T2D) patients with chronic kidney disease (CKD) while revealing only a low risk of hyperkalemia. However, the effect of finerenone on CV and renal outcomes has not yet been investigated in long-term trials. Patients and Methods: The Finerenone in Reducing CV Mortality and Morbidity in Diabetic Kidney Disease (FIGARO-DKD) trial aims to assess the efficacy and safety of finerenone compared to placebo at reducing clinically important CV and renal outcomes in T2D patients with CKD. FIGARO-DKD is a randomized, double-blind, placebo-controlled, parallel-group, event-driven trial running in 47 countries with an expected duration of approximately 6 years. FIGARO-DKD randomized 7,437 patients with an estimated glomerular filtration rate >= 25 mL/min/1.73 m(2) and albuminuria (urinary albumin-to-creatinine ratio >= 30 to <= 5,000 mg/g). The study has at least 90% power to detect a 20% reduction in the risk of the primary outcome (overall two-sided significance level alpha = 0.05), the composite of time to first occurrence of CV death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for heart failure. Conclusions: FIGARO-DKD will determine whether an optimally treated cohort of T2D patients with CKD at high risk of CV and renal events will experience cardiorenal benefits with the addition of finerenone to their treatment regimen. Trial Registration: EudraCT number: 2015-000950-39; ClinicalTrials.gov identifier: NCT02545049

Comparative Genomics Analysis of Plasmid pPV989-94 from a Clinical Isolate of Pantoea vagans PV989

Pantoea vagans, a gram-negative bacterium from the genus Pantoea and family Enterobacteriaceae, is present in various natural environments and considered to be plant endophytes. We isolated the Pantoea vagans PV989 strain from the clinic and sequenced its whole genome. Besides a chromosome DNA molecule, it also harboured three large plasmids. A comparative genomics analysis was performed for the smallest plasmid, pPV989-94. It can be divided into four regions, including three conservative regions related to replication (R1), transfer conjugation (R2), and transfer leading (R3), and one variable region (R4). Further analysis showed that pPV989-94 is most similar to plasmids LA637P2 and pEA68 of Erwinia amylovora strains isolated from fruit trees. These three plasmids share three conservative regions (R1, R2, and R3). Interestingly, a fragment (R4′) in R4, mediated by phage integrase and phage integrase family site-specific recombinase and encoding 9 genes related to glycometabolism, resistance, and DNA repair, was unique in pPV989-94. Homologues of R4′ were found in other plasmids or chromosomes, suggesting that horizontal gene transfer (HGT) occurred among different bacteria of various species or genera. The acquired functional genes may play important roles in the adaptation of bacteria to different hosts or environmental conditions