The functionality of products increases when more sensors are used. This trend also affects future automobiles and becomes even more relevant in connected and autonomous applications. Concerning ...automotive lightweight design, carbon fibre-reinforced polymers (CFRP) are suitable materials. However, their drawbacks include the relatively high manufacturing costs of CFRP components in addition to the difficulty of recycling. To compensate for the increased expenditure, the integration of automotive sensors in CFRP vehicle structures provides added value. As a new approach, established sensors are integrated into fibre-reinforced polymer (FRP) structures. The sensors are usually mounted to the vehicle. The integration of sensors into the structure saves weight and space. Many other approaches specifically develop new sensors for integration into FRP structures. With the new approach, there is no need for elaborate development of new sensors since established sensors are used. The present research also showed that the range of applications of the sensors can be extended by the integration. The present paper outlines the functional behaviour of the integrated sensor utilized for crashing sensing. First of all, the integration quality of the sensor is relevant. Different requirements apply to the usual mounting of the sensor. The self-sensing structure must fulfil those requirements. Moreover, unfamiliar characteristics of the new surrounding structure might affect the sensing behaviour. Thus, the sensing behaviour of the self-sensing composite was analyzed in detail. The overarching objective is the general integration of sensors in products with reasonable effort.
The appearance of fretting fatigue cracks in bolted sheets limits their lifetime. Furthermore, repairing these failures requires much effort due to needing to replace the components instead of ...replacing just the bolt. To prevent such failures, the purpose of this study is to understand the failure mechanism and to identify the major influencing parameters. Therefore, a representative joint of a bolt of size M22 and sheet material were investigated by experiments and a finite element analysis. The experiments were conducted over a wide range of preloads from zero to maximum preload. It turned out that the failure mode changes at 50 kN. For this preload, the influence of the surface and the use of a lubricant was observed. A grinded surface as well as the use of lubricant showed a change in the failure mode. The accompanying simulation showed that an analysis of the stresses delivers no proper explanation for the observed effects in the experiment. Therefore, the contact status was analyzed for various preloads and friction coefficients. The results correlate with the change in the failure mode. The conclusion is that both the stress state and the tribological behavior influence the failure mode and have to be considered in a numerical analysis.
Ground Vehicle Dynamics offers a common approach to sophisticated mathematical modelling and dynamical analysis of ground vehicle systems composed of the vehicle body, the propulsion, guidance and ...suspension devices and the corresponding guideway.
Ropeways are one of the most effective way to transport passengers or goods within minimum space requirements and with high transportation capacities in conjunction with a high safety level. Hence, ...ropeways are preferably used in mountainous regions as well as for urban transport. However, due to their functional principle, ropeways dissipate plenty of energy based on damping and friction effects. This paper focuses on the analysis of the energy consumption of ropeways and presents possible improvements, which may reduce the total energy consumption up to 20%. In terms of climate change and green marketing this could be one key point to implement sustainable tourism in ski regions. First, an analytical model is described, which enables the analysis of monocable ropeway systems in a stationary state. The model delivers physical values like the forces at the towers and the power consumption, which is separated into parts for transportation, the power loss of the drive, the power consumption of the stations and the power loss of the sheaves. As an improvement to the ropeway standard DIN EN 12930, the rolling resistance coefficient will be considered as velocity-dependent. The model is parametrized by measurement data of a representative ropeway. Second, the main parameters of the mechanical system such as the velocity or the number of vehicles are analyzed concerning their influence on the energy consumption. Finally, three possible energy-saving strategies are described, which provide a significant reduction of the energy consumption without any modifications in the mechanical system or by reducing the transport capacity.
Background:
Therapeutic treatment options for chronic autoimmune disorders such as multiple sclerosis (MS) rely largely on the use of non-specific immunosuppressive drugs, which are not able to cure ...the disease. Presently, approaches to induce antigen-specific tolerance as a therapeutic approach; for example, by peptide-based tolerogenic ‘inverse’ vaccines have regained great interest. We have previously shown that coupling of peptides to carriers can enhance their capacity to induce regulatory T cells in vivo.
Method:
In this present study, we investigated whether the tolerogenic potential of immunodominant myelin T-cell epitopes can be improved by conjugation to the synthetic carrier polyethylene glycol (PEG) in an experimental autoimmune encephalomyelitis (EAE) mouse model for chronic MS (MOG C57BL/6).
Results:
Preventive administration of the PEGylated antigenic peptide could strongly suppress the development of EAE, accompanied by reduced immune cell infiltration in the central nervous system (CNS). Depletion of regulatory T cells (Tregs) abrogated the protective effect indicating that Tregs play a crucial role in induction of antigen-specific tolerance in EAE. Treatment during the acute phase of disease was safe and did not induce immune activation. However, treatment at the peak of disease did not affect the disease course, suggesting that either induction of Tregs does not occur in the highly inflamed situation, or that the immune system is refractory to regulation in this condition.
Conclusion:
PEGylation of antigenic peptides is an effective and feasible strategy to improve tolerogenic (Treg-inducing) peptide-based vaccines, but application for immunotherapy of overt disease might require modifications or combination therapies that simultaneously suppress effector mechanisms.
Magnetorheological elastomers (MREs) are smart materials whose mechanical properties, like their modulus and elasticity, can be controlled by an external magnetic field. This feature has resulted in ...a number of novel applications, such as adaptive tuned dynamic vibration absorbers for suppressing unwanted vibrations over a wide frequency range. MRE-based devices operate in different modes, such as shear mode and squeeze mode; however, the study of mechanical performances of MREs under squeeze mode is very rare. This article aims to investigate MRE performances under both shear and squeeze modes. Experimental studies and simulations were conducted to analyze the MR effect in both modes. These studies indicate a different working frequency ranges for both modes. In a case study, a MRE-based vibration absorber was built up in a simulation and its mechanical performances were analyzed, which demonstrated good capabilities in reducing vibrations.
Experimental investigation on the avoidance of self-excited vibrations Kröger, Matthias; Neubauer, Marcus; Popp, Karl
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
03/2008, Letnik:
366, Številka:
1866
Journal Article
Recenzirano
Self-excited vibrations are observed in many technical applications. Frictional contacts are often involved in the mechanism which generates vibrations. Reasons for the excitation mechanisms are ...decreasing friction characteristics depending on the sliding velocity, fluctuating normal loads or different geometrical effects. First, the mechanisms are explained using simple examples. The practical relevance of self-excited, friction-induced vibrations is exemplified with three technical systems: a system with an axial seal; a tread block of a tyre; and a disc brake. The knowledge of the excitation mechanism is necessary to introduce successfully design countermeasures. These measures to avoid self-excited vibrations are important to solve practical problems. They are the main focus of this work. Further, additional passive and active subsystems are described and validated experimentally. Therefore, a large range of design, active and passive solutions are given.
In recent years, Non-small cell lung cancer (NSCLC) has evolved into a prime example for precision oncology with multiple FDA-approved “precision” drugs. For the majority of NSCLC lacking targetable ...genetic alterations, immune checkpoint inhibition (ICI) has become standard of care in first-line treatment or beyond. PD-L1 tumor expression represents the only approved predictive biomarker for PD-L1/PD-1 checkpoint inhibition by therapeutic antibodies. Since PD-L1-negative or low-expressing tumors may also respond to ICI, additional factors are likely to contribute in addition to PD-L1 expression. Tumor mutation burden (TMB) has emerged as a potential candidate; however, it is the most complex biomarker so far and might represent a challenge for routine diagnostics. We therefore established a hybrid capture (HC) next-generation sequencing (NGS) assay that covers all oncogenic driver alterations as well as TMB and validated TMB values by correlation with the assay (F1CDx) used for the CheckMate 227 study. Results of the first consecutive 417 patients analyzed in a routine clinical setting are presented. Data show that fast reliable comprehensive diagnostics including TMB and targetable alterations are obtained with a short turn-around time. Thus, even complex biomarkers can easily be implemented in routine practice to optimize treatment decisions for advanced NSCLC.
Myeloma cells express basic fibroblast growth factor (bFGF), an angiogenic cytokine triggering marrow neovascularization in multiple myeloma (MM). In solid tumors and some lymphohematopoietic ...malignancies, angiogenic cytokines have also been shown to stimulate tumor growth via paracrine pathways. Since interleukin-6 (IL-6) is a potent growth and survival factor for myeloma cells, we have studied the effects of bFGF on IL-6 secretion by bone marrow stromal cells (BMSCs) and its potential reverse regulation in myeloma cells. Both myeloma-derived cell lines and myeloma cells isolated from the marrow of MM patients were shown to express and secrete bFGF. Cell-sorting studies identified myeloma cells as the predominant source of bFGF in MM marrow. BMSCs from MM patients and control subjects expressed high-affinity FGF receptors R1 through R4. Stimulation of BMSCs with bFGF induced a time- and dose-dependent increase in IL-6 secretion (median, 2-fold;P< .001), which was completely abrogated by anti-bFGF antibodies. Conversely, stimulation with IL-6 enhanced bFGF expression and secretion by myeloma cell lines (2-fold;P= .02) as well as MM patient cells (up to 3.6-fold; median, 1.5-fold;P= .002). This effect was inhibited by anti–IL-6 antibody. When myeloma cells were cocultured with BMSCs in a noncontact transwell system, both IL-6 and bFGF concentrations in coculture supernatants increased 2- to 3-fold over the sum of basal concentrations in the monoculture controls. The IL-6 increase was again partially, but significantly, inhibited by anti-bFGF. The data demonstrate a paracrine interaction between myeloma and marrow stromal cells triggered by mutual stimulation of bFGF and IL-6.
The influence of a friction hysteresis on the self-exciting in a particle-solid-system will be investigated by experiments and a numerical model. For this, a test rig will be presented. This test rig ...allows to measure the actual acting friction force. Furthermore, a numerical model will be presented which has a differentiation between a time-dependent friction behavior in sliding and sticking. Bigger differences can be observed in the system behavior – even with a quality similar curve of the measured friction hysteresis. For example, in a system with PVC-W particles exists a sharp boundary between an area of stable stick-slip oscillation and an area of subsiding oscillation. In comparison to this, a system with PMMA particles has a smooth transition region between these two areas. The followed simulation studies shown, that the selfexciting mechanism is a complex interaction between the time-dependent behavior during the sliding and sticking and the external average system velocity.
PDF
