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991.
Janine Glänzel Arnd Meyer Roman Unger Michael Bräunig Volker Wittstock Steffen Ihlenfeldt 《The International Journal of Advanced Manufacturing Technology》2017,88(5-8):1279-1288
A new interdisciplinary approach is discribed to identifying unknown parameters using an extended version of the known interval bisection method. This developed method is based on the use of finite elements for calibrating the simulation calculation. The resulting thermo-elastic deformations which occur in drilling processes with impaired cooling lubrication are to be used as correction values for tool positioning in the NC control. Based on the strong impact on workpiece temperature of machining, a simulation approach is presented for calculating the temperature fields and their thermo-elastic consequences. In addition, methods are presented to correct these effects. This paper particularly deals with the temperature fields of drilling operations. Special attention is paid to the technique employed for iterative numerical determination of the unknown heat flux η w and heat transfer coefficient \(\bar {\gamma }\) values. Finally, the data obtained from experiments are compared with those achieved by numerical simulation in order to verify the efficiency of simulation and determination of parameters. 相似文献
992.
Wirtz T Fleming Y Gerard M Gysin U Glatzel T Meyer E Wegmann U Maier U Odriozola AH Uehli D 《The Review of scientific instruments》2012,83(6):063702
State-of-the-art secondary ion mass spectrometry (SIMS) instruments allow producing 3D chemical mappings with excellent sensitivity and spatial resolution. Several important artifacts however arise from the fact that SIMS 3D mapping does not take into account the surface topography of the sample. In order to correct these artifacts, we have integrated a specially developed scanning probe microscopy (SPM) system into a commercial Cameca NanoSIMS 50 instrument. This new SPM module, which was designed as a DN200CF flange-mounted bolt-on accessory, includes a new high-precision sample stage, a scanner with a range of 100 μm in x and y direction, and a dedicated SPM head which can be operated in the atomic force microscopy (AFM) and Kelvin probe force microscopy modes. Topographical information gained from AFM measurements taken before, during, and after SIMS analysis as well as the SIMS data are automatically compiled into an accurate 3D reconstruction using the software program "SARINA," which was developed for this first combined SIMS-SPM instrument. The achievable lateral resolutions are 6 nm in the SPM mode and 45 nm in the SIMS mode. Elemental 3D images obtained with our integrated SIMS-SPM instrument on Al/Cu and polystyrene/poly(methyl methacrylate) samples demonstrate the advantages of the combined SIMS-SPM approach. 相似文献
993.
MA Dobbs M Lueker KA Aird AN Bender BA Benson LE Bleem JE Carlstrom CL Chang HM Cho J Clarke TM Crawford AT Crites DI Flanigan T de Haan EM George NW Halverson WL Holzapfel JD Hrubes BR Johnson J Joseph R Keisler J Kennedy Z Kermish TM Lanting AT Lee EM Leitch D Luong-Van JJ McMahon J Mehl SS Meyer TE Montroy S Padin T Plagge C Pryke PL Richards JE Ruhl KK Schaffer D Schwan E Shirokoff HG Spieler Z Staniszewski AA Stark K Vanderlinde JD Vieira C Vu B Westbrook R Williamson 《The Review of scientific instruments》2012,83(7):073113
A technological milestone for experiments employing transition edge sensor bolometers operating at sub-Kelvin temperature is the deployment of detector arrays with 100s-1000s of bolometers. One key technology for such arrays is readout multiplexing: the ability to read out many sensors simultaneously on the same set of wires. This paper describes a frequency-domain multiplexed readout system which has been developed for and deployed on the APEX-SZ and South Pole Telescope millimeter wavelength receivers. In this system, the detector array is divided into modules of seven detectors, and each bolometer within the module is biased with a unique ~MHz sinusoidal carrier such that the individual bolometer signals are well separated in frequency space. The currents from all bolometers in a module are summed together and pre-amplified with superconducting quantum interference devices operating at 4 K. Room temperature electronics demodulate the carriers to recover the bolometer signals, which are digitized separately and stored to disk. This readout system contributes little noise relative to the detectors themselves, is remarkably insensitive to unwanted microphonic excitations, and provides a technology pathway to multiplexing larger numbers of sensors. 相似文献
994.
Roland Meyer Jens K?hler Berend Denkena 《The International Journal of Advanced Manufacturing Technology》2012,58(9-12):933-940
Hard turning has become an alternative machining process for grinding processes of hardened steels. One challenge during hard turning is the increasing wear during the operation time of the tool and the hereby influenced workpiece surface and subsurface properties. This causes unfavorable changes of the microstructure and residual stress state or rather damages of the subsurface. Important factors are the contact conditions between the tool and the workpiece. The width of flank wear land influences the size of the passive force significantly. This has a direct impact on the subsurface properties of the workpiece. One solution is to modify the contact conditions and thereby the specific mechanical and thermal loads that are applied to the tool as well as to the workpiece. This article presents an experimental approach of modified corner radius geometry of cutting tools for hard turning processes. Hereby, the size and direction of the contact length of the cutting edge are adjusted as well as the load impact during machining. The aim is to reduce the tool wear performance. The results show the potential of the load-specific tool design concerning the tool wear and the workpiece subsurface properties. Furthermore, a new approach for predicting the process forces during hard turning is presented. 相似文献
995.
The dependence of high-resolution transmission electron microscopy (HRTEM) image contrast of graphene on the adjustable parameters of an aberration-corrected microscope operated at 80 and 20 kV has been calculated and, for 80 kV, compared with measurements. We used density functional theory to determine the projected atom potential and obtained the image intensity by averaging over the energy distribution of the imaging electrons, as derived from the electron energy loss spectroscopy measurements. Optimum image contrast has been determined as a function of energy spread of the imaging electrons and chromatic aberration coefficient, showing that significant improvement of contrast can be achieved at 80 kV with the help of a monochromator, however at 20 kV only with chromatic aberration correction and bright atom contrast conditions. 相似文献
996.
The angular dependence of potassium emission-desorption is studied from a fused iron catalyst of the type used for ammonia synthesis. The excited species (K*, K
n
*
, etc.) and positive ions K+ have strongly different angular distributions. The bilobular distribution measured for ion desorption is concluded to be either due to excited atoms, so-called Rydberg atoms, or excited clusters. Both types of species have to desorb from the edges of the sample and become field ionized and deexcited just outside the sample, as reported in previous studies on an iron oxide catalyst. The peak in the normal direction measured for excited species is due to excited cluster formation outside the catalyst surface. Similarities with previous results for other catalysts are observed. The possibility that the promoter function of potassium in the ammonia synthesis is due to excited species is pointed out.On leave from Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Cracow, Poland. 相似文献
997.
C. Amatore A. Jutand G. Meyer P. Bourhis F. Machetto J. -M. Mallet P. Sinaÿ C. Tabeur Y. -M. Zhang 《Journal of Applied Electrochemistry》1994,24(8):725-729
Summary
O-glycosides were synthesized by electrochemical oxidation of phenylS-glycosides in the presence of primary alcohols in acetonitrile. Similarly, a -linked disaccharide was obtained selectively by oxidation of phenylS-glycoside in the presence of a sugar alcohol. Electrosyntheses were performed under controlled potential or at constant current, in an undivided cell, on a large scale. 1 to 60 g of phenylS-glycosides in 0.5 to 1 dm3 of acetonitrile were converted with chemical yields in the range of 65–75%. 相似文献
998.
Although electron beams with energies of a few keV can excite fluorescent X-ray production from solids, ion beams of comparable energy cannot do so. The reason for this situation is that it is the velocity of the incident particle, rather than its energy, which determines whether an ionization event can be generated. 相似文献
999.
Baller MK Lang HP Fritz J Gerber C Gimzewsk JK Drechsler U Rothuizen H Despont M Vettiger P Battiston FM Ramseyer JP Fornaro P Meyer E Guntherodt HJ 《Ultramicroscopy》2000,82(1-4):1-9
We present quantitative and qualitative detection of analyte vapors using a microfabricated silicon cantilever array. To observe transduction of physical and chemical processes into nanomechanical motion of the cantilever, swelling of a polymer layer on the cantilever is monitored during exposure to the analyte. This motion is tracked by a beam-deflection technique using a time multiplexing scheme. The response pattern of eight cantilevers is analyzed via principal component analysis (PCA) and artificial neural network (ANN) techniques, which facilitates the application of the device as an artificial chemical nose. Analytes tested comprise chemical solvents, a homologous series of primary alcohols, and natural flavors. First differential measurements of surface stress change due to protein adsorption on a cantilever array are shown using a liquid cell. 相似文献
1000.
A new method is presented for the determination of the antisymmetric coefficients of the wave aberration function from a tableau of tilted illumination images. The approach is based on measurements of the apparent defocus and two-fold astigmatism using a phase correlation function and phase contrast index calculated from a short focus series acquired at each tilt. This method is shown to be suitable for a wide range of specimens and is sufficiently accurate for exit plane wave restoration at 0.1 nm resolution. Experimental examples of this approach are provided and the method is compared to results obtained from measurements of conventional power spectra. 相似文献