Construction of the Jordan basis for the Baker map

The Jordan canonical form basis states for an invertible chaotic map, the Baker map, are constructed. A straightforwardly obtained recursion formula is presented for construction of the Jordan states and of the spectral decomposition of the Frobenius-Perron evolution operator. Comparison of this method with earlier, subdynamics techniques demonstrates that it is much more direct and simpler. The physical significance of the Jordan states is approached from the point of view of an entropy evolution equation. The method is also applied to the Bernoulli map, yielding its eigenstates more straightforwardly than done previously. (c) 1997 American Institute of Physics.     

Comparison of AlGaN/GaN MSM Varactor Diodes Based on HFET and MOSHFET Layer Structures

In this letter, the performance of AlGaN/GaN-based metal-semiconductor-metal (MSM) varactor diodes based on HFET and MOSHFET layer systems is investigated. Passivated HFET MSM devices are coated with a 10-nm-thick SiO₂ layer between the electrodes; in MOSHFET-based diodes, this layer is also used as an insulator underneath the gate. Device fabrication uses standard HFET fabrication technology, allowing easy integration in monolithic microwave integrated circuits. Devices with different electrode geometry are characterized by direct current and by S-parameter measurements up to 50 GHz. The HFET-based varactors show capacitance ratios up to 14 and cutoff frequencies up to 74 GHz. The MOSHFET-based devices, on the other hand, show lower capacitance ratios and poorer stability because of the insulation layer between electrodes and semiconductor     

Common black coatings – reflectance and ageing characteristics in the 0.32–14.3 μm wavelength range

The diffuse and regular reflectances of five optically absorbing coatings frequently used in optical systems, were measured over the 0.32–14.3 μm wavelength range, before and after exposure to heat and intense optical radiation. The measured coatings included Nextel Velvet Black, an anodised coating and NPL Super Black. The anodised coating exhibited substantial variations in its diffuse and regular reflectance values after thermal and simulated solar ageing. Solar and thermal ageing of the Nextel Velvet Black resulted in increases of its reflectance. However, thermal ageing tended to decrease the reflectance of the other paint samples examined. Thermal and solar ageing of the NPL Super Black resulted in only minor changes in its reflectance characteristics. All measurements are traceable to the UK National Standards.     

An Ontology for Quality Management — Enabling Quality Problem Identification and Tracing

The TOVE Quality Ontology-VB is the formal representation (using First-order Logic) of terms, relationships, attributes, and axioms about quality which are generic beyond any specific quality domain. The assumption that quality is 'conformance to requirements' is used to decompose the quality domain into domains of measurement, identification, and traceability for further exploration; the TOVE Quality Ontology-VB is comprised of ontologies of these domains. An ontological engineering methodology comprised of motivating scenario, scope, and competency question statements, data model and axiom construction, and competency question/answer visualisation is demonstrated. The methodology is applied to develop the TOVE Traceability Ontology-VB. This ontology's representations are used to construct quality control applications enabling quality problem identification and tracing. They also enforce the properties of an entity that make it traceable — a novel and useful feature for quality control applications.     

Surface analysis of particulates from laboratory hood exhaust manifold

Particulate samples collected from a laboratory ventilation manifold during routine maintenance were analyzed to determine if particulate composition had changed as a result of changes in the laboratory's atmosphere. This ventilation manifold exhausts more than 100 fume hoods. The particulate samples were analyzed using static secondary ion mass spectrometry (SIMS). The negative SIMS spectra showed abundant Cl^?, NO₃^?, and HSO₄^?, consistent with the use of mineral acids in the laboratory. Cluster anions containing primarily Zn (but also other transition metals) were detected, which signaled corrosion of the manifold's galvanized steel by the volatilized acids. The most abundant ions in the cation SIMS spectra were derived from cyclohexylamine (CHA), which had been used as an antiscaling agent in the facility's boiler. Steam from the boiler, which contained CHA, was used to humidify the building air; this practice stopped in 1997. The abundances of the CHA‐derived ions were significantly lower in the samples collected in 2004 and 2006 than in the 1992 samples, indicating that the CHA is being slowly depleted. Changes in the relative abundances suggest exponential depletion from the manifold with rate constants that are on the order of 0.01 to 0.04 month^?1. Published in 2007 John Wiley & Sons, Ltd.     

Cost-effective integration of an FN-programmed embedded flash memory into a 0.25 μm SiGe:C RF-BiCMOS technology

 This paper presents a process technology for cost-effective integration of low-power flash memories into a 0.25 μm, high performance SiGe:C RF-BiCMOS process. Only four additional lithographic steps are used on top of the baseline BiCMOS process, leading to in total 23 mask levels for the BiCMOS/embedded flash process. Uniform-channel Fowler-Nordheim programmable and erasable stacked-gate cells, suitable for medium density (∼Mbit) memories, are demonstrated. Peripheral high-voltage transistors, with >10 V breakdown voltage, are integrated without additional mask steps on top of the flash cell integration. The flash memory integration is modular and has negligible impact on the original CMOS and HBT device parameters.