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Jani Heikkinen Jussi Rantala Thomas Olsson Roope Raisamo Jani Lylykangas Jukka Raisamo Veikko Surakka Teemu Ahmaniemi 《Journal of Visual Languages and Computing》2009,20(5):287-304
Haptic gestures and sensations through the sense of touch are currently unavailable in remote communication. There are two main reasons for this: good quality haptic technology has not been widely available and knowledge on the use of this technology is limited. To address these challenges, we studied how users would like to, and managed to create spatial haptic information by gesturing. Two separate scenario-based experiments were carried out: an observation study without technological limitations, and a study on gesturing with a functional prototype with haptic actuators. The first study found three different use strategies for the device. The most common gestures were shaking, smoothing and tapping. Multimodality was requested to create the context for the communication and to aid the interpretation of haptic stimuli. The second study showed that users were able to utilize spatiality in haptic messages (e.g., forward–backward gesture for agreement). However, challenges remain in presenting more complex information via remote haptic communication. The results give guidance for communication activities that are usable in spatial haptic communication, and how to make it possible to enable this form of communication in reality. 相似文献
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S. Ahmaniemi J. Tuominen P. Vuoristo T. Mäntylä 《Journal of Thermal Spray Technology》2002,11(3):320-332
Zirconia-based 8Y2O3-ZrO2 and 22MgO-ZrO2 thick thermal barrier coatings (TTBC, 1000 μm), were studied with different sealing methods for diesel engine applications.
The aim of the sealing procedure was to improve hot corrosion resistance and mechanical properties of porous TBC coatings.
The surface of TTBCs was sealed with three different methods: (1) impregnation with phosphate-based sealant, (2) surface melting
by laser glazing, and (3) spraying of dense top coating with a detonation gun. The thicknesses of the densified top layers
were 50–400 μm, depending on the sealing procedure. X-ray diffraction (XRD) analysis showed some minor phase changes and reaction
products caused by phosphate-based sealing treatment and some crystal orientation changes and phase changes in laser-glazed
coatings. The porosity of the outer layer of the sealed coating decreased in all cases, which led to increased microhardness
values. The hot corrosion resistance of TTBCs against 60Na2SO4-40V2O5 deposit was determined in isothermal exposure at 650 °C for 200 h. Corrosion products and phase changes were studied with
XRD after the test. A short-term engine test was performed for the reference coatings (8Y2O3-ZrO2 and 22MgO-ZrO2) and for the phosphate-sealed coatings. Engine tests, duration of 3 h, were performed at the maximum load of the engine and
were intended to evaluate the thermal cycling resistance of the sealed coatings. All of the coatings passed the engine test,
but some vertical cracks were detected in the phosphate-sealed coatings. 相似文献
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J. Tuominen P. Vuoristo T. Mäntylä S. Ahmaniemi J. Vihinen P. H. Andersson 《Journal of Thermal Spray Technology》2002,11(2):233-243
Thermal spray processes are widely used to deposit high-chromium, nickel-chromium coatings to improve high temperature oxidation
and corrosion behavior. However, despite the efforts made to improve the present spraying techniques, such as high-velocity
oxyfuel (HVOF) and plasma spraying, these coatings may still exhibit certain defects, such as unmelted particles, oxide layers
at splat boundaries, porosity, and cracks, which are detrimental to corrosion performance in severe operating conditions.
Because of the process temperature, only mechanical bonding is obtained between the coating and substrate. Laser remelting
of the sprayed coatings was studied in order to overcome the drawbacks of sprayed structures and to markedly improve the coating
properties. The coating material was high-chromium, nickel-chromium alloy, which contains small amounts of molybdenum and
boron (53.3% Cr, 42.5% Ni, 2.5% Mo, 0.5% B). The coatings were prepared by HVOF spraying onto mild steel substrates. A high-power,
fiber-coupled, continuous-wave Nd:YAG laser equipped with large beam optics was used to remelt the HVOF-sprayed coating using
different levels of scanning speed and beam width (10 or 20 mm). Coating that was remelted with the highest traverse speed
suffered from cracking because of the rapid solidification inherent to laser processing. However, after the appropriate laser
parameters were chosen, nonporous, crack-free coatings with minimal dilution between coating and substrate were produced.
Laser remelting resulted in the formation of a dense oxide layer on top of the coatings and full homogenization of the sprayed
structure. The coatings as sprayed and after laser remelting were characterized by optical and electron microscopy (OM, SEM,
respectively). Dilution between coating and substrate was studied with energy dispersive spectrometry (EDS). The properties
of the laser-remelted coatings were directly compared with properties of as-sprayed HVOF coatings. 相似文献
4.
Minnamari Vippola Samppa Ahmaniemi Petri Vuoristo Toivo Lepistö Tapio Mäntylä Eva Olsson 《Journal of Thermal Spray Technology》2002,11(2):253-260
Microstructural characterization of aluminum phosphate-sealed, plasma-sprayed chromium oxide coating was carried out in order
to study the strengthening mechanisms of the aluminum phosphate sealant in the coating. Characterization was performed using
x-ray diffractometry, scanning electron microscopy, and analytical transmission electron microscopy. The structure of the
sealed coating was lamellar with columnar α-Cr2O3 grains extending through the lamella thickness. Amorphous aluminum phosphate sealant had penetrated into the structural defects
of the coating such as cracks, gaps, and pores between the lamellae. The relative composition was 25 at.% aluminum and 75
at.% phosphorus for the sealant in the coating, giving the molar ratio P/Al of 3, which corresponds to that of metaphosphates
Al(PO3)3. There is no indication of reaction products from the chemical reactions between the sealant and the coating. Thus, the aluminum
phosphate sealing in the chromium oxide coatings can be explained mainly by adhesive binding resulting from the formation
of the condensed phosphates with the appropriate adhesive properties to the coating, and not by chemical bonding resulting
from the chemical reactions between the sealant and the coating. 相似文献
5.
Characterization of modified thick thermal barrier coatings 总被引:1,自引:0,他引:1
Ahmaniemi S. Tuominen J. Vippola M. Vuoristo P. Mäntylä T. Cernuschi F. Gualco C. Bonadei A. Di Maggio R. Ahmaniemi S. 《Journal of Thermal Spray Technology》2004,13(3):361-369
In gas turbines and diesel engines, there is a demand for thick thermal barrier coatings (TTBCs) due to the increased process
combustion temperatures. Unfortunately, the increased thickness of plasma-sprayed thermal barrier coatings (TBCs) normally
leads to a reduced coating lifetime. For that reason, the coating structures have to be modified. When modifying the structure
of TTBCs, the focus is normally on elastic modulus reduction of the thick coating to improve the coating strain tolerance.
On the other hand, coating structural modification procedures, such as sealing treatments, can be performed when increased
hot-corrosion resistance or better mechanical properties are needed. In this article, several modified zirconia-based TTBC
structures with specific microstructural properties are discussed. Coating surface sealing procedures such as phosphate sealing,
laser glazing, and sol-gel impregnation were studied as potential methods for increasing the hot-corrosion and erosion resistance
of TTBCs. Some microstructural modifications also were made by introducing segmentation cracks into the coating structures
by laser glazing and by using special spraying parameters. These last two methods were studied to increase the strain tolerance
of TTBCs. The coating microstructures were characterized by optical microscopy, a scanning electron microscopy (SEM), transmission
electron microscopy (TEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD). The effect of sealing procedures
on the basic thermal and mechanical properties of the coatings was studied. In addition, some correlations between the coating
properties and microstructures are also presented, and the advantages and drawbacks of each modification procedure are discussed. 相似文献
6.
S. Ahmaniemi P. Vuoristo T. Mntyl C. Gualco A. Bonadei R. Di Maggio 《Surface & coatings technology》2005,190(2-3):378-387
The thermal cycling properties of several modified thick thermal barrier coatings (TTBC) were studied in three test series in which the maximum coating temperature was fixed to 1000, 1150 and 1300 °C. The modified coating structures were all segmentation-cracked coatings and some of these coatings were surface-sealed. The segmentation-cracked coatings were produced by laser glazing or by using appropriate plasma spray parameters. The sealing treatments were made by using aluminium phosphate or sol–gel-based sealant. In this paper, it was demonstrated that regardless of whether the segmentation-cracked TTBCs were made by using specific plasma spray parameters or by laser glazing, the strain tolerance of the coating improved significantly. Instead, both sealing treatments reduced the thermal cycling resistance of the TTBCs to some degree, especially in the case of aluminium phosphate sealing. Coating microstructures, their mechanical and elastic properties and residual stresses were taken into consideration when estimating the thermal cycling properties and failure modes of the coatings. 相似文献
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