Passwörter — fünf Mythen und fünf Versäumnisse

Bis heute wird der Zugriff auf Daten und Anwendungen überwiegend durch einen Passwortschutz kontrolliert. Oft ist dieser Passwortschutz jedoch unzureichend, weil sich für die Gestaltung von und den Umgang mit Passworten hartn?ckig unrichtige überzeugungen halten und die falschen Priorit?ten gesetzt werden.     

Stable and metastable phase equilibria in the Al-Mn system

The aim of the present investigation was resolution of certain obscure features of the Al-Mn phase diagram. The experimental approach was guided by assessment of the previous literature and modeling of the thermodynamics of the system. It has been shown that two phases of approximate stoichiometry “Al₄Mn” (λ and μ) are present in stable equilibrium, λ forming by a peritectoid reaction at 693 ± 2 °C. The liquidus and stable equilibrium invariant reactions as proposed by Goedecke and Koester have been verified. A map has been made of the successive nonequilibrium phase transformations of as-splat-quenched alloys. Finally, the thermodynamic calculation of the phase diagram allows interpretation of complex reaction sequences during cooling in terms of a catalogue of all the metastable invariant reactions involving (Al), Al₆Mn, λ, μ, ϕ, and Al₁₁Mn₄ phases.     

High-fidelity lightwave transmission of multiple AM-VSB NTSCsignals

The progress towards developing AM lightwave links for the transmission of multiple TV signals is reported. While the signal-quality objectives and transmission distances are appropriate for CATV trunking, the technology is expected to have applicability to the distribution of video signals in the subscriber loop. Highly linear 1.3-μm distributed feedback (DFB) lasers designed expressly for analog requirements are used to transmit 42 continuous wave carriers according to the standard US CATV frequency plan. For the best lasers, when evaluated over 12 km of fiber, carrier to noise was >52 dB, composite second-order distortion was >70 dBc, and composite triple beat was >70 dBc. The relationship between measurements with continuous wave carriers and actual video signals is discussed. System design rules are offered. Properties that lead to superior analog performance are discussed. Data from 700 links indicate that composite third-order distortion generally scales with product count but that composite second-order distortion has a significant frequency-dependent component     

Ab initio molecular dynamics simulation for structural transition of Zr during rapid quenching processes

We report the results of ab initio molecular dynamics simulation for the structural transition of Zr during two distinct quenching processes (Q1: 4.3 × 10¹³ K/s, Q2: 2.0 × 10¹⁴ K/s). In both the quenching processes, structural transition details have been analyzed by pair correlation functions g(r) and bond pair analysis technique. It is shown that the liquid Zr transforms to a metastable bcc phase (β-Zr) at the temperature about 1000 K as quenched at the rate of 4.3 × 10¹³ K/s. When quenched at 2.0 × 10¹⁴ K/s, however, the crystallization is suppressed and the liquid Zr is frozen into a glass state. The bond pair analysis reveals that the dominant bond pairs in the liquid and glass states are the 1551, 1541, 1431, 1661 and 1441, indicating that the short range order in both states mostly consists of icosahedral, tetrahedral and bcc clusters.     

嵌入式系统专家部落格(ind River Blog) BMW寻求迈向开放之路

Eclipse Foundation行销总监lan Skerrett在MotorAuthority,com表示,BMW正在探寻市场,看看主流制造商是否有兴趣为车用娱乐信息系统开发一个开放来源堆栈.     

Neutralization of acid in the rumen by magnesium oxide and magnesium carbonate

Two reagent and two feed grade magnesium oxides and reagent grade magnesium carbonate, sodium bicarbonate, and calcium carbonate were evaluated to ascertain their ability to neutralize acid in the rumen. Rumen fluid pH was increased in vitro, compared to the control, by antacid compounds, and their increased ranked: calcium carbonate less than feed grade magnesium oxide A less than light magnesium oxide and feed grade magnesium oxide B less than heavy magnesium oxide less than magnesium carbonate less than sodium bicarbonate. Titrations at constant pH's ranging from 3.0 to 7.5 indicated that these magnesium compounds were reactive at pH's normally in the rumen although reactivity decreased with increasing pH. Intraruminal doses of feed grade magnesium oxide A and calcium carbonate did not change rumen fluid pH for other compounds ranked: feed grade magnesium oxide B less than magnesium carbonate less than heavy magnesium oxide. Feeding of heavy magnesium oxide or magnesium carbonate increased rumen fluid pH as compared to the control diet. Feeding feed grade magnesium oxide B in three quantities to cattle resulted in proportional increased in fecal pH and fluidity of feces. Two feed grade magnesium oxides differed in their ability to neutralize acid in the rumen.     

Atomic Force Microscope Techniques for Adhesion Measurements

The Atomic Force Microscope (AFM) has become a powerful apparatus for performing real-time, quantitative force measurements between materials. Recently the AFM has been used to measure adhesive interactions between probes placed on the AFM cantilever and sample surfaces. This article reviews progress in this area of adhesion measurement, and describes a new technique (Jump Mode) for obtaining adhesion maps of surfaces. Jump mode has the advantage of producing fast, quantitative adhesion maps with minimal memory usage.