Showing papers by "Fraunhofer Society published in 1999"

A unified framework for coupling measurement in object-oriented systems

Abstract: The increasing importance being placed on software measurement has led to an increased amount of research developing new software measures. Given the importance of object-oriented development techniques, one specific area where this has occurred is coupling measurement in object-oriented systems. However, despite a very interesting and rich body of work, there is little understanding of the motivation and empirical hypotheses behind many of these new measures. It is often difficult to determine how such measures relate to one another and for which application they can be used. As a consequence, it is very difficult for practitioners and researchers to obtain a clear picture of the state-of-the-art in order to select or define measures for object-oriented systems. This situation is addressed and clarified through several different activities. First, a standardized terminology and formalism for expressing measures is provided which ensures that all measures using it are expressed in a fully consistent and operational manner. Second, to provide a structured synthesis, a review of the existing frameworks and measures for coupling measurement in object-oriented systems takes place. Third, a unified framework, based on the issues discovered in the review, is provided and all existing measures are then classified according to this framework. This paper contributes to an increased understanding of the state-of-the-art: A mechanism is provided for comparing measures and their potential use, integrating existing measures which examine the same concepts in different ways, and facilitating more rigorous decision making regarding the definition of new measures and the selection of existing measures for a specific goal of measurement. In addition, our review of the state-of-the-art highlights that many measures are not defined in a fully operational form, and relatively few of them are based on explicit empirical models, as recommended by measurement theory.

A unified framework for coupling measurement in object-oriented systems

Abstract: The increasing importance being placed on software measurement has led to an increased amount of research developing new software measures. Given the importance of object-oriented development techniques, one specific area where this has occurred is coupling measurement in object-oriented systems. However, despite a very interesting and rich body of work, there is little understanding of the motivation and empirical hypotheses behind many of these new measures. It is often difficult to determine how such measures relate to one another and for which application they can be used. As a consequence, it is very difficult for practitioners and researchers to obtain a clear picture of the state of the art in order to select or define measures for object-oriented systems. This situation is addressed and clarified through several different activities. First, a standardized terminology and formalism for expressing measures is provided which ensures that all measures using it are expressed in a fully consistent and operational manner. Second, to provide a structured synthesis, a review of the existing frameworks and measures for coupling measurement in object-oriented systems takes place. Third, a unified framework, based on the issues discovered in the review, is provided and all existing measures are then classified according to this framework. This paper contributes to an increased understanding of the state-of-the-art.

Optical Bloch Oscillations in Temperature Tuned Waveguide Arrays

Abstract: We report the observation of optical Bloch oscillations in waveguide arrays. The required linear variation of the propagation constant across the thermo-optic polymer array was obtained by applying a temperature gradient. Bloch oscillations manifesting themselves as transverse oscillations of the propagating light beam can be attributed to the existence of localized states (Wannier-Stark states) with equidistant eigenvalue spacing (Wannier-Stark ladder). The period and amplitude of the oscillations can be controlled by varying the temperature gradient.

PuLSE: a methodology to develop software product lines

Abstract: Software product lines have recently been introduced as one of the most promising advances for efficient software development. Yet upon close examination, there are few guidelines or methodologies available to develop and deploy product lines beyond existing domain engineering approaches. The latter have had mixed success within commercial enterprises because of their deployment complexity, lack of customizability, and especially their misplaced focus, that is on domains as opposed to products. To tackle these problems we developed the PuLSETM (Product Line Software Engineering) methodology for the purpose of enabling the conception and deployment of software product lines within a large variety of enterprise contexts. This is achieved via product-centric focus throughout the phases of PuLSETM, customizability of its components, incremental introduction capability, maturity scale for structured evolution, and adaptations to a few main product development situations. PuLSETM is the result of a bottom-up effort: the methodology captures and leverages the results (the lessons learned) from our technology transfer activities with our industrial customers. We present in this paper the main ideas behind PuLSETM and illustrate the methodology with a running example taken from our transfer experience.

Geometry-based watermarking of 3D models

Abstract: This article addresses the fundamentals of geometry-based watermarking. It presents a watermarking algorithm that modifies normal distribution to invisibly store information in the model's geometry.

MP3 and AAC Explained

Abstract: The proliferation of MPEG coded audio material on the Internet has shown an exponential growth since 1995, making ”.mp3” the most searched for term in early 1999 (according to http://www.searchterms.com). ”MP3” has been featured in numerous articles in newspapers and periodicals and on TV, mostly on the business pages because of the potential impact on the recording industry. While everybody is using MP3, not many (including some of the software authors writing MP3 encoders, decoders or associated tools) know the history and the details of MPEG audio coding. This paper explains the basic technology and some of the special features of MPEG1/2 Layer-3 (aka MP3). It also sheds some light on the factors determining the quality of compressed audio and what can be done wrong in MPEG encoding and decoding.

An assessment and comparison of common software cost estimation modeling techniques

Abstract: This paper investigates two essential questions related to data-driven, software cost modeling: (1) What modeling techniques are likely to yield more accurate results when using typical software development cost data? and (2) What are the benefits and drawbacks of using organization-specific data as compared to multi-organization databases? The former question is important in guiding software cost analysts in their choice of the right type of modeling technique, if at all possible. In order to address this issue, we assess and compare a selection of common cost modeling techniques fulfilling a number of important criteria using a large multi-organizational database in the business application domain. Namely, these are: ordinary least squares regression, stepwise ANOVA, CART, and analogy. The latter question is important in order to assess the feasibility of using multi-organization cost databases to build cost models and the benefits gained from local, company-specific data collection and modeling. As a large subset of the data in the multi-company database came from one organization, we were able to investigate this issue by comparing organization-specific models with models based on multi-organization data. Results show that the performances of the modeling techniques considered were not significantly different, with the exception of the analogy-based models which appear to be less accurate. Surprisingly, when using standard cost factors (e.g., COCOMO-like factors, Function Points), organization specific models did not yield better results than generic, multi-organization models.

Investigating quality factors in object-oriented designs: an industrial case study

Abstract: This paper aims at empirically exploring the relationships between most of the existing coupling and cohesion measures for object-oriented (OO) systems, and the fault-proneness of OO system classes. The underlying goal of such a study is to better understand the relationship between existing design measurement in OO systems and the quality of the software developed. The study described here is a replication of an analogous study conducted in an university environment with systems developed by students. In order to draw more general conclusions and to (dis)confirm the results obtained there, we now replicated the study using data collected on an industrial system developed by professionals. Results show that many of our findings are consistent across systems, despite the very disparate nature of the systems under study. Some of the strong dimensions captured by the measures in each data set are visible in both the university and industrial case study. For example, the frequency of method invocations appears to be the main driving factor of fault-proneness in all systems. However, there are also differences across studies which illustrate the fact that quality does not follow universal laws and that quality models must be developed locally, wherever needed.

Using coupling measurement for impact analysis in object-oriented systems

Abstract: Many coupling measures have been proposed in the context of object oriented (OO) systems. In addition, due to the numerous dependencies present in OO systems, several studies have highlighted the complexity of using dependency analysis to perform impact analysis. An alternative is to investigate the construction of probabilistic decision models based on coupling measurement to support impact analysis. In addition to providing an ordering of classes where ripple effects are more likely, such an approach is simple and can be automated. In our investigation, we perform a thorough analysis on a commercial C++ system where change data has been collected over several years. We identify the coupling dimensions that seem to be significantly related to ripple effects and use these dimensions to rank classes according to their probability of containing ripple effects. We then assess the expected effectiveness of such decision models.

A model of isoprene emission based on energetic requirements for isoprene synthesis and leaf photosynthetic properties for Liquidambar and Quercus

Abstract: We present a physiological model of isoprene (2-methyl-1,3-butadiene) emission which considers the cost for isoprene synthesis, and the production of reductive equivalents in reactions of photosynthetic electron transport for Liquidambar styraciflua L. and for North American and European deciduous temperate Quercus species. In the model, we differentiate between leaf morphology (leaf dry mass per area, MA, g m−2) altering the content of enzymes of isoprene synthesis pathway per unit leaf area, and biochemical potentials of average leaf cells determining their capacity for isoprene emission. Isoprene emission rate per unit leaf area (μmol m−2 s−1) is calculated as the product of MA, the fraction of total electron flow used for isoprene synthesis (ɛ, mol mol−1), the rate of photosynthetic electron transport (J) per unit leaf dry mass (Jm, μmol g−1 s−1), and the reciprocal of the electron cost of isoprene synthesis [mol isoprene (mol electrons−1)]. The initial estimate of electron cost of isoprene synthesis is calculated according to the 1-deoxy- D-xylulose-5-phosphate pathway recently discovered in the chloroplasts, and is further modified to account for extra electron requirements because of photorespiration. The rate of photosynthetic electron transport is calculated by a process-based leaf photosynthesis model. A satisfactory fit to the light-dependence of isoprene emission is obtained using the light response curve of J, and a single value of ɛ, that is dependent on the isoprene synthase activity in the leaves. Temperature dependence of isoprene emission is obtained by combining the temperature response curves of photosynthetic electron transport, the shape of which is related to long-term temperature during leaf growth and development, and the specific activity of isoprene synthase, which is considered as essentially constant for all plants. The results of simulations demonstrate that the variety of temperature responses of isoprene emission observed within and among the species in previous studies may be explained by different optimum temperatures of J and/or limited maximum fraction of electrons used for isoprene synthesis. The model provides good fits to diurnal courses of field measurements of isoprene emission, and is also able to describe the changes in isoprene emission under stress conditions, for example, the decline in isoprene emission in water-stressed leaves.

Industrial processing of polymers by low-pressure plasmas: the role of VUV radiation

Abstract: The use of low-pressure plasmas for materials processing, pioneered by the semiconductor industry since the 1960s, is now also a commercial reality in technologies which make extensive use of plastics (automotive, aerospace, packaging, pharmaceutical, textile, and other industries). A large fraction of these processes involve the surface modification of polymers for improved adhesion, and many of these use air or oxygen plasma to incorporate polar functional groups into the polymer surfaces. Interaction mechanisms between a plasma and a polymer surface are very complex, for they include synergistic effects of physical bombardment by energetic particles and by ultraviolet photons, and resulting chemical reactions at and below the surface. In this article we present an overview of plasma surface modification of polymers, in which we identify the main variables for process control, illustrated by examples. We then show, on hand of a series of specially designed experiments, how the effects of ultraviolet photons generated in the plasma can be assessed separately from those of other energetic and reactive species, especially in the case of oxidizing plasmas. Finally, we comment on the merits and drawbacks of industrial plasma processes in comparison with other competing technologies, especially those based on ultraviolet radiation.

Defining and validating measures for object-based high-level design

Abstract: The availability of significant measures in the early phases of the software development life-cycle allows for better management of the later phases, and more effective quality assessment when quality can be more easily affected by preventive or corrective actions. We introduce and compare various high-level design measures for object-based software systems. The measures are derived based on an experimental goal, identifying fault-prone software parts, and several experimental hypotheses arising from the development of Ada systems for Flight Dynamics Software at the NASA Goddard Space Flight Center (NASA/GSFC). Specifically, we define a set of measures for cohesion and coupling, which satisfy a previously published set of mathematical properties that are necessary for any such measures to be valid. We then investigate the measures' relationship to fault-proneness on three large scale projects, to provide empirical support for their practical significance and usefulness.

Augmented reality for construction tasks: doorlock assembly

Abstract: Augmented Reality is a technology that integrates pictures of virtual objects into images of the real world. Besides the technical problems still to be solved, for industry to be interested in this technology the additional amount of work needed to use the technology in relation to the benefit has to be visible. Furthermore the question how this integrates into the information technology infrastructure of the company is important. This paper describes an Augmented Reality demonstrator for the task of doorlock assembly into a car door that was developed trying to create a practical, realistic application that can transport the concepts behind Augmented Reality to a casual observer. To reach that goal a new fast and robust optical tracking algorithm was developed and integrated into a three-dimensional animation and rendering system, creating a real-time fully three-dimensional HMDbased training application showing how to assemble the doorlock into the door. The system was demonstrated to the general public at the Hannover Industrial Fair 1998 and this demonstration of Augmented Reality for one of the first times to a large non-expert audience created a lot of interest into this new area.

III-V compounds for solar cell applications

Abstract: Research activities in the field of III-V solar cells are reviewed. III-V compound semiconductors are used for space solar cells, concentrator solar cells, and in thermophotovoltaic generators. The epitaxial growth of ternary and quaternary material by MOVPE and LPE allows us to realize various band gaps. Multi-junction solar cells with different band gaps are necessary to obtain efficiencies larger than 30%. Recent results of the III-V solar cell research at the Fraunhofer ISE are presented. A mechanically stacked GaAs/GaSb tandem concentrator solar cell achieved an efficiency of 31.1% under 100×AM1.5d. An efficiency of 23% for a two-terminal concentrator module (486 cm2) with Fresnel lenses has been measured under realistic outdoor conditions.

Data intermixing and multi-volume rendering

Abstract: The main difference between multi-volume rendering and mono-volume rendering is data intermixing. In this paper, we present three levels of data intermixing and their rendering pipelines in direct multi-volume rendering, which discriminate image level intensity intermixing, accumulation level opacity intermixing, and illumination model level parameter intermixing. In the context of radiotherapy treatment planning, different data intermixing methods are applied to three volumes, including CT volume, Dose volume, and Segmentation volume, to compare the features of different data intermixing methods.

Transformation of diamond to graphite

Abstract: Despite almost forty years of trying, no one has managed to transform diamond into graphite under pressure1, or find out what the pressure limit for diamond might be2. If diamond were to behave like other group IV elements, such as silicon, germanium or tin, it would transform under compressive indentation to the β-tin structure3, but it does not2,4. Here we use micro-Raman spectroscopy to determine what happens to diamond when it is subjected to high contact compression as a result of pressing a sharp diamond indenter against its surface4. We find that, under this non-hydrostatic compression, diamond at the point of indentation is transformed into disordered graphite. This discovery may eventually lead to the more efficient machining of diamond.

Texturing 3D Models of Real World Objects from Multiple Unregistered Photographic Views

Abstract: As the efficiency of computer graphic rendering methods is increasing, generating realistic models is now becoming a limiting factor In this paper we present a new technique to enhance already existing geometry models of real world objects with textures reconstructed from a sparse set of unregistered still photographs The aim of the proposed technique is the generation of nearly photo-realistic models of arbitrarily shaped objects with minimal effort In our approach, we require neither a prior calibration of the camera nor a high precision of the user's interaction Two main problems have to be addressed of which the first is the recovery of the unknown positions and parameters of the camera An initial estimate of the orientation is calculated from interactively selected point correspondences Subsequently, the unknown parameters are accurately calculated by minimising a blend of objective functions in a 3D-2D projective registration approach The key point of the proposed method of registration is a novel filtering approach which utilises the spatial information provided by the geometry model Second, the individual images have to be combined yielding a set of consistent texture maps We present a robust method to recover the texture from the photographs thereby preserving high spatial frequencies and eliminating artifacts, particularly specular highlights Parts of the object not seen in any of the photographs are interpolated in the textured model Results are shown for three complex example objects with different materials and numerous self-occlusions

Carbon films with an sp 2 network structure

Abstract: Laser-arc evaporation of a graphite target has been used to deposit carbon films that exhibit high hardness (45 GPa) and elastic recovery (85%). High-resolution electron microscopy (HREM) and electron energy loss spectroscopy (EELS) were subsequently used to study the microstructure and bonding of the resultant layers. The structure of the films from HREM is seen to consist of a dense array of parallel curved graphene sheet segments packed in various orientations. EELS reveals that the films are comprised of mainly ${\mathrm{sp}}^{2}$-bonded carbon. The results suggest that a form of carbon thin film with fullerenelike structure can be realized. In order to explain how a predominantly ${\mathrm{sp}}^{2}$-bonded material can exhibit such a high hardness, a simple model is proposed to correlate the excellent mechanical properties with the observed structure.

A systematic approach to derive the scope of software product lines

Abstract: Product line scoping is a critical activity because it elicits the common realms upon which the different products of a product line can be optimally engineered with respect to economies of scope. This, in turn, upper bounds the overall economic benefits that can be accrued from product line based development. Inherently, product line scoping is difficult because of the complexity of the factors that must be taken into account. Many are not known a priori. Traditional scoping approaches (from domain engineering) have focused on the notion of application domains. However, domains proved difficult to optimally scope and engineer from an enterprise standpoint because a domain captures extraneous elements that are of no interest to an enterprise which must focus on particular products, whether existing, under development, or anticipated. Hence, the domain view provides a flawed economic basis for making a scoping decision. We introduce PuLSE-Eco, a technique especially developed to address the aforementioned issues. Its main characteristics are: a complete product-centric orientation done via product maps, the separation of concerns achieved through the definition and operationalization of strategic business objectives, and last, diverse types of analyses performed upon product maps allowing scoping decisions based on these objectives. We illustrate the technique with a running example.

Isoprene synthase activity and its relation to isoprene emission in Quercus robur L. leaves

Abstract: Pedunculate oak (Quercus robur L.) is known as a strong isoprene (2-methyl-1,3-butadiene) emitter. Diurnal changes in isoprene emission were determined by branch enclosure measurements. In contrast to the diurnal cycle in emission rates, specific isoprene synthase activity in the leaves remained unchanged. Based on in vitro enzyme activity and its temperature dependency, an isoprene synthesis capacity at specific leaf temperatures was calculated. The comparison of these 'leaf temperature-dependent enzyme capacities' and the measured emission rates revealed that the enzyme activity of isoprene synthase is comparable to the observed isoprene emission rates. In addition, variation in the isoprene synthase activity of the leaves due to changes in light intensity during leaf development was investigated. A 50% reduction of light intensity by shading of single branches reduced isoprene synthase activity by [almost equal to] 60% compared with full sunlight. The calculation of isoprene synthesis capacities based on enzymatic data obtained under optimum reaction conditions, corrected for actual leaf temperature and related to leaf surface area, provides a sound basis for predicting the isoprene emission potential of plants.