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41.
Public sector organizations increasingly form interorganizational networks that rely on technology to achieve what they cannot achieve independently. The governance of these public sector networks is complex due to the nature of interorganizational relationships and technology. This paper aims to increase our understanding of network governance by exploring the evolution of governance over the 40+ year lifespan of a public sector network. The historical case study is based on the technology affordance and organizational actualization concepts applied to three critical incidents in the history of a public safety network. The incidents provide evidence that technology and governance do interact, that timing matters and that future research is needed to understand more fully how and why network governance evolves and the implications of governance evolution on network performance.  相似文献   
42.
Digitale Zertifikate werden bereits in großem Umfang zur Verschlüsselung mit Desktop Clients wie Outlook eingesetzt. Damit ein Benutzer auch an all seinen Mobilgeräten verschlüsselte E-Mails lesen und an beliebige Empfänger verschlüsseln kann, müssen sein privater Schlüssel sowie die Zertifikate der Partner dort verfügbar sein.  相似文献   
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44.
Cold forging is a group of methods effectively used in a number of industrial applications to form aluminium. Tool life and complexity of the possible shapes are mainly restricted by galling; the uneven tool surfaces caused by lumps of transferred material lead to surface damage on successive parts formed and/or problems in successive forming operations, and high stresses occurring when forming complex shapes. Earlier investigations have shown that improved surface roughness of an uncoated steel tool decreases the amount of adhered aluminium on the tool, but does not decrease the friction in the long run. Testing has also shown that when using conventional forming tools it is very important to have sufficient lubrication to avoid galling. Addition of an optimized low-friction PVD-coating decreases the galling tendency and increases the tolerance to insufficient lubrication and lubricant film breakthrough, as long as the coating surface is smooth, whilst other similar coatings have little or no effect. The present article further investigates the mechanism behind the transfer of aluminium to the coatings. All coatings were found to be intact after testing, and so the differences were concluded to lie in the chemical properties of the coating and, if these are favourable, then in surface roughness on the micro scale.  相似文献   
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46.
Oxidation of Metals - Vaporization often accompanies high-temperature oxidation and corrosion. In this review, vaporization under a vacuum as well as static gas and flowing gas conditions is...  相似文献   
47.
Photopolymerizable liquid encapsulants (PLEs) for microelectronic devices may offer important advantages over traditional transfer molding compounds, including reduced in‐mold cure times, lower thermal stresses, and reduced wire sweep. In this contribution, we discuss an encapsulation process based upon a low viscosity resin that cures rapidly upon exposure to UV light. These highly filled PLEs are comprised of an epoxy novolac‐based vinyl ester resin (~25 wt %), fused silica filler (70–74 wt %), photoinitiator, silane coupling agent, and, in some cases, a thermal initiator. We have characterized the material properties (flexural strength and modulus, coefficient of thermal expansion, glass transition temperature, and thermal stress parameter) of PLEs cured with UV illumination times of 60, 90, and 120 s, as well as, the thermal conductivity and adhesive peel strength of PLEs photocured for 90 s. In addition, we investigated the effect of the fused silica loading and the initiation scheme on these properties. The results indicate that the PLEs are very promising for microelectronic encapsulation. These liquid encapsulants cure (to an ejectable hardness) in 1 min for an initiating light intensity of 200 mW/cm2, and exhibit appropriate values for the thermal and mechanical properties listed above. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3449–3461, 2001  相似文献   
48.
Thermodynamic parameters are reported for gaseous hydroxides and oxyhydroxides of Al, Zr, and Y. The structures and vibrational frequencies are calculated using density functional theory with the B3LYP functional. This yields entropies at 298.15 K and heat capacities. The enthalpies are calculated from appropriate reactions and the CCSD(T) (Coupled Cluster, Singles, Doubles, and perturbative Triples) approach. The hydroxide groups are treated as hindered rotors for all species. The results are compared to the limited experimental and theoretical calculations for these species. Finally, the data are put into a database for a free-energy minimizer and the vapor pressures for each species are compared.  相似文献   
49.
The high-temperature stability of alumina (Al2O3) in argon and argon/water-vapor (Ar/H2O) environments has been investigated. Samples were exposed at temperatures of 1300°C–1700°C for 10 h. The microstructure, flexural strength, and volume all showed significant changes in the Ar/H2O environment at 1700°C. Samples also became whiter, because of the oxidation of graphite impurities that had diffused from the hot-processing dies. In the Ar/H2O environment at 1700°C, grain-boundary etching occurred and was much more severe than in the pure-argon environment, which was very likely caused by the enhanced formation of gaseous Al(OH)3 and Al(OH)2 along grain boundaries. In addition, in the Ar/H2O environment, substantial grain growth occurred in the surface vicinity. This grain growth, together with grain-boundary etching, led to a decrease in flexural strength.  相似文献   
50.
Nextel? 610 alumina fibers and alumina‐YAG (yttrium‐aluminum garnet) matrices were used to make oxide‐oxide ceramic matrix composites (CMCs) with and without monazite (LaPO4) fiber‐matrix interfaces. Twelve sequential aluminum oxychloride (AlOCl) infiltrations with 1 hour heat treatments at 1100°C and a final 1 hour heat treatment at 1200°C were used for matrix densification. This matrix processing sequence severely degraded CMC mechanical properties. CMC tensile strengths and interlaminar tensile (ILT) strengths were less than 10 MPa and 1 MPa, respectively. Axial fracture of Nextel? 610 fibers was observed after ILT testing, highlighting the extreme degradation of fiber strength. Extensive characterization was done to attempt to determine the responsible degradation mechanisms. Changes in Nextel? 610 fiber microstructure after CMC processing were characterized by optical microscopy, SEM, and extensively by TEM. In AlOCl degraded fibers, grain boundaries near the fiber surface were wetted with a glass that contained Y2O3/SiO2 or Y2O3/La2O3/P2O5/SiO2, and near‐surface pores were partially filled with Al2O3. This glass must also contain some Al2O3 and initially some chlorine. AlOCl decomposition products were predicted using the FactSage® Thermochemical code, and were characterized by mass spectrometry. Effects of AlOCl precursors on monazite coated and uncoated Nextel? 610 fibers tow and filament strength were evaluated. A mechanism for the severe degradation of the oxide‐oxide CMCs and Nextel? 610 fibers that involves subcritical crack growth promoted by release of chlorine containing species during breakdown of intergranular glasses in an anhydrous environment is proposed.  相似文献   
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