Through Process Modelling of Surface Densified PM Gears

Through process modelling of surface densified gears produced by powder metallurgy (PM) was established by coupling the modelling of the manufacturing processes surface densification, carburization, and heat treatment. The complete model allows the prediction of the local microstructure and hardness in the gear as well as the appearance and direction of residual stresses in the final part. The structural integrity of the part is governed, on the one hand, by the local material properties and residual stresses and, on the other hand, by the load stresses calculated for typical operating conditions. A simplified hardness dependent Haigh diagram was used to calculate the maximum allowable cyclic stresses for the gear tooth and to derive a local utilization ratio as target entity for optimization of the individual steps of the production chain.     

Prozessmodell zum Einbringen von Eigenspannungen durch Festwalzen

Defects in axles lead to a significant reduction of lifetime. Deep rolling provides a simple way to prevent crack growth emanating from defects or at least to slow down the crack growth rate, provided the flaw size does not exceed the size of the zone affected by the compressive residual stresses. In this work, a simple process model is presented for estimating the penetration depth of compressive residual stresses from deep rolling.     

Simulation of tribological functionality of heterogeneous tribomaterials

We simulated the tribological functionality of two heterogeneous tribomaterials used in conformal contacts by means of a FEM-based approach: journal bearing material AlSn20 and polymeric sealing material PTFE with bronze filler particles. For AlSn20, the emergency running capability, which is based on the activation (melting) of the soft phase tin, was simulated taking into account thermo-elasto-plastic behaviour of the material. For the PTFE bronze compound, we analysed the load bearing capacity of the particle-structured surface with varying volumetric fraction of particles, temperature, load and creep behaviour of the PTFE Matrix. The results show benefit of heterogeneous designs over homogeneous materials.     

Neuroproteomics in stem cell differentiation

The term "proteome" is used to describe the entire complement of proteins in a given organism or in a system at a given time. Proteome analysis in neuroscience, also called "neuroproteomics" or "neuromics" is in its initial stage, and shows a deficit of studies in the context of brain development. It is the main objective of this review to illustrate the potential of neuroproteomics as a tool to unravel the differentiation of neural stem or progenitor cells to terminally differentiated neurons. Experimental results regarding the rat striatal progenitor model cell line ST14A are presented to illustrate the large rearrangements of the proteome during the differentiation process of neural progenitor cells and their modification by neurotrophic factors like the glial cell line-derived neurotrophic factor (GDNF). Thereby native stem cells and cells transfected with GDNF gene were investigated at the proliferative state and at seven time points up to 72?h after induction of differentiation. In addition, the immortalized human fetal midbrain stem cell line ReNcell VM was analyzed in order to detect stem cell differentiation associated changes of the protein profile. This review gives also an outlook on technical improvements and perspectives of application of neural stem cell proteomics.     

Error Analysis for Finite Element Simulation of Orthogonal Cutting and its Validation Via Quick Stop Experiments

This work focuses on the chip formation during gun drilling of a 50CrMo₄ (DIN 1.7228, AISI 4150) steel grade with a fixed set of cutting parameters and a fresh coated tool. Chip roots were investigated by means of quick stop experiments providing a measured chip width d at the chip root. Furthermore, the tool-chip contact length, L, was measured with high accuracy. Rastegaev compression tests were performed at different temperatures and strain rates for material characterization. The measured data was fit with the Johnson–Cook material model. A 2D finite element (FE) model of the orthogonal cutting process was set up starting with modelling data from literature. A parameter study was performed to determine the sensitivity of the prediction of d and L to the input parameters, i.e., the discretization, the modelling of friction and the material model. The presented error analysis of both the experimental and the numerical investigations shall serve as error estimation for similar FE simulations of the cutting process aiming at the prediction of the tool loading and/or the chip formation and breaking. Authors who have to rely on literature data may use the results presented in this work to estimate the resulting error.     

Treatment of advanced colorectal cancer with folinic acid and 5-fluorouracil in combination with cisplatinum

51 patients with metastatic colorectal cancer (stage Dukes D) were treated with intravenous (i.v.) infusion on days 1, 3, 5, 8 and 16 with folinic acid (200 mg/m2) and 5-fluorouracil (600 mg/m2), and on days 1, 8 and 16 with cisplatinum (25 mg/m2 i.v.); cycles were repeated every 4 weeks. All 51 patients were evaluable for toxicity and response criteria. 26 patients had objective responses (3 complete responses, 5.9%; 23 partial responses, 45.1%), relative risk 51% (95% confidence intervals 36.7-65.0%). Response duration ranged from 4 to 28.0 months (median 16.8). Overall median survival of all patients included was 14.7 months (range 3.0-33.0). Toxicity of WHO grade III, requiring dose reduction, occurred in 9 (18%) patients. The regimen described here appears to be active, safe and well tolerated for treatment of patients with advanced colorectal cancer.     

Effiziente 3‐D numerische Simulation im Tunnel und Kavernenbau

Efficient 3‐D numerical Simulation in Underground Construction Due to several reasons 3‐D analyses of tunnels or caverns are rarely performed in practical applications. The reasons are the high effort of mesh generation and the long computing times. The simulation of a powerhouse cavern reported here it is definitely a 3‐D problem that can not be reduced to a two‐dimensional model. The aim of the numerical simulation reported here was to determine the reasons for the occurrence of cracks in the concrete wall of the powerhouse cavern and to determine the likelihood that these cracks will propagate further. It will be shown that by using a coupled Finite Element/Boundary Element approach the effort in simulation can be reduced considerably.     

Detecting Intention Through Motor-Imagery-Triggered Pupil Dilations

Human–computer interaction systems that bypass manual control can be beneficial for many use cases, including users with severe motor disability. We investigated pupillometry (inferring mental activity via dilations of the pupil) as an interaction method because it is noninvasive, easy to analyse, and increasingly available for practical development. In 3 experiments we investigated the efficacy of using pupillometry to detect imaginary motor movements of the hand. In Experiment 1 we demonstrated that, on average, the pupillary response is greater when the participant is imagining a hand-grasping motion, as compared with the control condition. In Experiment 2 we investigated how imaginary hand-grasping affects the pupillary response over time. In Experiment 3 we employed a simple classifier to demonstrate single-trial detection of imagined motor events using pupillometry. Using the mean pupil diameter of a single trial, accuracy rates as high as 71.25%, were achieved. Implications for the development of a pupillometry-based switch and future directions are discussed.