Toward a formal research framework for ontological analyses

Ontological analyses have been used in numerous publications to compare existing modelling grammars with an ontology. However, a sound theoretical research framework is still missing. Consequently, working with the results of such ontological analyses is theoretically questionable. Therefore, the aim of this paper is threefold. Firstly, we want to contribute to such a theoretical research framework by formalising the ontological analyses approach as sets of mathematical functions between ontological and modelling grammar constructs. Secondly, on this basis, we derive four formal requirements each ontological analyses must comply with. Thirdly, we analyse whether current state of the art ontological analyses comply with our findings. While the formalisation demonstrates the strengths of the ontological analysis approach we conclude that current analyses have theoretical deficiencies, which lead to serious limitations in their application. Lastly, we demonstrate the usefulness of our formal framework by describing a new application. This application uses two different ontological analyses as input and produces mappings between the modelling grammars used in these analyses as output.     

Histochemical analysis of bandage contact lens precipitates.

Contact lens deposits have been reported previously with extended wear of soft contact lenses, with proteins, lipids, mucous, and various salts such as chloride, potassium and calcium being deposited on the lens surface [1]. We report an unusual case of precipitates on the surface of a bandage contact lens (BCL) following intensive treatment with topical preservative free artificial tears. Evaluation included microscopic and histochemical analysis of the BCL. We have also reviewed the literature for previous reports of contact lens precipitates.     

Alkaline Injection of Concentrated Sodium Hydroxide Solution into an Acidic Surface Mine Spoil Aquifer

A series of NaOH solution injection experiments were performed as trials for in situ remediation of an acid-producing surface-mine spoil. Both 20 and 50% (w/w) concentrated NaOH solutions were employed. While the spoil immediately down-gradient of the injection wells was neutralized, only about 23% of the introduced Na was recovered at the spring discharge in 3 years of post-injection monitoring. This rate of transport was far slower than the estimated advection rates in the aquifer, indicating that substantial retardation of both Na and the associated alkalinity occurred. This retardation is ascribed to: precipitation of alkaline-earth carbonate hydroxide minerals, as well as metal hydroxide precipitates, consuming injected alkalinity; and reduction of hydraulic conductivity in the peralkaline (pH > 13) “plume” region due to plugging by reaction products. It is likely that Na and alkalinity will continue to leak from this plume region for many years, but at too slow a rate to neutralize AMD at current concentrations. Future injection efforts of this type may be feasible but should use lower concentrations and should be focused further down-gradient, in closer proximity to the springs, where ground water velocities are higher.     

Enhanced electrical properties of nominally undoped Si/SiGe heterostructure nanowires grown by molecular beam epitaxy

Electrical properties of epitaxial single-crystalline Si/SiGe axial heterostructure nanowires (NWs) on Si〈1 1 1〉 substrate were measured by contacting individual NWs with a micro-manipulator inside an scanning electron microscope. The NWs were grown by incorporating compositionally graded Si_1−xGe_x segments of a few nm thicknesses in the Si NWs by molecular beam epitaxy. The I-V characteristics of the Si/SiGe heterostructure NWs showed Ohmic behavior. However, the resistivity of a typical heterostructure NW was found to be significantly low for the carrier concentration extracted from the simulated band diagram. Similarly grown pure Si and Ge NWs showed the same behavior as well, although the I-V curve of a typical Si NW was rectifying in nature instead of Ohmic. It was argued that this enhanced electrical conductivities of the NWs come from the current conduction through their surface states and the Ge or Si/SiGe NWs are more strongly influenced by the surface than the Si ones.     

Requantization for transcoding of MPEG-2 intraframes

An investigation on requantization for transcoding of video signals is carried out. Specifically, MPEG-2 compatible discrete cosine transform (DCT) intraframe coding is addressed. The aim of this work is twofold: first, to provide a theoretical analysis of the transcoding problem, and second, to derive quantization methods for efficient transcoding based on the results of the analysis. The mean squared error (MSE) cost function is proposed for designing a quantizer with minimum distortion resulting in up to 1.3 dB gain compared with the quantizer used in the MPEG-2 reference coder TM5. However, the MSE quantizer leads in general to a larger bit rate and may therefore only be applied locally to blocks of sensitive image content. A better rate-distortion performance can be provided by the maximum a posteriori (MAP) cost function. In critical cases, the MAP quantizer gives a 0.4 dB larger signal-to-noise-ratio (SNR) at the same bit rate compared with the TM5 quantizer. The results are not limited to MPEG-2 and can be adapted to other coding schemes such as H.263 or JPEG.     

Employing industrial standards in software engineering for W7X

The stellarator W7X is a large complex experiment designed for continuous operation and planned to be operated for about 20 years. Software support is highly demanded for experiment preparation, operation and data analysis which in turn induces serious non-functional requirements on the software quality like, e.g.:

• high availability, stability, maintainability vs.

• high flexibility concerning change of functionality, technology, personnel

• high versatility concerning the scale of system size and performance

These challenges are best met by exploiting industrial experience in quality management and assurance (QM/QA), e.g. focusing on top-down development methods, developing an integral functional system model, using UML as a diagramming standard, building vertical prototypes, support for distributed development, etc., which have been used for W7X, however on an ‘as necessary’ basis. Proceeding in this manner gave significant results for control, data acquisition, corresponding database-structures and user applications over many years.As soon as production systems started using the software in the labs or on a prototype the development activity demanded to be organized in a more rigorous process mainly to provide stable operation conditions. Thus a process improvement activity was started for stepwise introduction of quality assuring processes with tool support taking standards like CMMI, ISO-15504 (SPICE) as a guideline. Experiences obtained so far will be reported.We conclude software engineering and quality assurance has to be an integral part of systems engineering right from the beginning of projects and be organized according to industrial standards to be prepared for the challenges of nuclear fusion research.