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Die vorliegende Arbeit untersucht die Frage, wie bei Architekten und Ingenieuren Unternehmensstrategien entstehen. Dabei geht es nicht um die Identifikation einer guten oder schlechten, einer erfolgreichen, oder einer weniger erfolgreichen Art der Strategiegenese, sondern um die Frage, ob bei Architekten und Ingenieuren überhaupt in dem gleichen Maß wie in industriellen oder großen Unternehmen von Strategien und ihrer Entstehung gesprochen werden kann und ob sich gängige Theorien hierzu – freilich mit gewissen Modifikationen – auf Architektur- und Ingenieurbüros übertragen lassen. Die Arbeit ist in zwei Teile gegliedert. Der erste, theoretische Teil leitet aus existierenden Theoriesträngen der Strategieforschung, der Architekturforschung, der Forschung zur Freien Berufen, der Organisationssoziologie und der Kreativitätsforschung einen geeigneten Untersuchungsbezugsrahmen ab. Dieser setzt sich im Wesentlichen aus einer Referenzmatrix zur Einordnung von Strategiegenesetypen und einem Bezugsrahmen zur Identifikation von Unternehmenszielen zusammen. Im zweiten, empirischen Teil der Arbeit werden vier Fallbeispiele großer Architektur- und Ingenieurbüros eingehend auf die Variablen des Untersuchungsbezugsrahmens hin untersucht. In den Architektur- und Ingenieurbüros wurden strukturierte Interviews mit Mitarbeitern aller Hierarchieebenen geführt, die einen detaillierten Einblick in die Arbeitsweise und die Form der Strategiegenese der Büros geben. Die empirischen Untersuchungen bestätigen weitgehend die Anwendbarkeit des theoretisch deduzierten Bezugsrahmens. Leichte Anpassungen einzelner Variablen sind für eine Weiterführung des Forschungsansatzes notwendig. Mögliche Erweiterungen des Forschungsansatzes liegen in großzahlig-quantitativen Untersuchungen, Langzeituntersuchungen einzelner Architektur- und Ingenieurbüros oder der Übertragung des Ansatzes auf andere kreative Dienstleistungsbranchen.
Adhesive bonding is the preferred bonding method for a lot of different application because of is particularities. As an example, adhesive bonding does not require to drill holes like for riveting or screwing. Thin and fragile material as well as of different arts can be successfully joined using adhesives. Moreover, adhesive bonding provides a uniform load distribution within the bonding joint during mechanical load. For these reasons, adhesive bonding should be used systemically for joining fiber reinforced polymers, since the fibers would be damaged by drilled holes. The mechanical properties of the parts given by the fibers would then remain. The problem is that it is very difficult to separate adhesively bonded structures. The first layer of fibers is often damaged by rough mechanical separation, or the resin matrix is damaged because of high temperatures applied. For these reasons, fibers reinforced polymers are up to now still very often screwed or riveted. New adhesive systems that allow debonding of structural bonding joints are developed and investigated in this work. For this purpose, epoxide and polyurethane adhesive are modified with foaming agents that weaken the adhesive above their expansion temperature. These modified adhesive should keep properties as close as possible to the properties of the unmodified adhesives. The expansion temperature should be above the upper service temperature of the adhesive as far as possible but also below the limit of the thermal stability of the substrates. This is contradictory and the window of temperature at which the expansion should take place is very narrow. In a second method, a commercial electrically disbonding adhesive is used in combination with fiber reinforced polymer substrates. This adhesive can be electrically disbonded by applying a voltage at the terminals of the adhesive. Therefore, electrically conductive substrates are necessary and the metallization of the fiber reinforced polymer substrates is investigated.
Im Rahmen dieser Untersuchung wurden insbesondere die Wechselbeziehungen zwischen dem Konzept des Universellen Designs im Wohnungsbau und der Gebäudeflexibilität analysiert, mit der Absicht festzustellen, was ein Gebäude grundsätzlich ausmachen muss, das einerseits auf die Veränderungen in den Lebens- und Wohngewohnheiten der Menschen reagieren sollte und andererseits die Prinzipien des Universellen Designs berücksichtigen muss. Darüber hinaus wurde mit der vorliegenden Forschungsarbeit versucht, die Informationslücken zum Thema des Universellen Designs im Wohnungsbau zu schließen und kritisch zu hinterfragen. Die gewonnenen Erkenntnisse dieser Arbeit sowie die Auswertung der Ergebnisse bei der Auswahl der untersuchten Fallbeispiele erlauben Rückschlüsse auf die Bedürfnisse der Menschen im Zusammenhang mit ihrer Wohnung bzw. ihrem Haus und werden dazu beitragen, Wohnungen zu schaffen, die den Wünschen ihrer Bewohner immer mehr entsprechen. Das vornehmliche Ziel dieser Untersuchung ist die Erarbeitung eines methodischen Standards zur Optimierung des Konzeptes des Universellen Designs. Ein wesentlicher Bestandteil stellt dabei die Entwicklung einer Evaluierungsmethode dar, die bisher als einzige Methode dieser Art die Prinzipien des Universellen Designs als Richtlinien zur Bewertung erhebt und somit das Konzept des Universellen Designs und seine Umsetzung im Wohnungsbau wesentlich bereichern kann. Die Forschungsarbeit ist in zwei Teile gegliedert: einen ersten theoretischen Teil, in dem der Fokus auf das vielschichtige Konzept des Universellen Designs und auf die damit verbundenen Begriffe gerichtet ist. Dort wird auch der gesellschaftliche Struktur- und architektonische Wohnwandel einer Analyse unterzogen. Und einen zweiten Teil, in dem Projektbeispiele untersucht wurden, die beispielhafte Lösungen im Bereich der Gebäudeflexibilität aufzeigen, die in der Lage sind, das Konzept des Universellen Designs im Wohnungsbau zu unterstützen.
Flüchtlingssozialarbeitende stehen in der Arbeit mit Menschen, die ihre Heimat verlassen mussten, nicht nur vor der Aufgabe, die formellen Voraussetzungen (Asylanträge, rechtliche Voraussetzungen für Duldungen und/oder Aufenthaltsbestimmungen etc.) innerhalb kürzester Zeit erfüllen zu müssen. Sie müssen parallel dazu den informellen Teil (Sprache, traumatische Fluchterfahrungen, Trauer und/oder Angst über zurückgebliebene Familienangehörige, mitgebrachte Traditionen etc.) integrieren. Bei dieser hohen Komplexität ist es wichtig in einem professionellen Netzwerk agieren zu können, um der Multikomplexität gerecht zu werden. Besonders in einem Flächenland wie Brandenburg stellt diese Form der Parallelität formeller und informeller Aufgaben eine besondere Herausforderung dar. Neben den professionell-organisierten Netzwerken, treffen wir in Brandenburg auf selbstorganisierte Netzwerke, kleine private Netzwerke und dem Netzwerk des Ehrensamtes. Im Rahmen einer Studie über Netzwerkarbeit in Brandenburg fand eine kurze Evaluation über vorhandene Netzwerke und deren Wirksamkeit statt, in deren Ergebnis die Idee einer Triangulation für eine höhere Effektivität zur Diskussion gestellt wird.
The oxy-fuel combustion process with subsequent CO2 storage has received attention as a promising technology for capturing CO2 from fossil fuel power plants. Recent progress in understanding pulverized coal combustion under oxy-fired conditions is attributable in part to studies performed at laboratory bench-scale. Previous investigations have underlined some significant differences between conventional air-fired and oxy-fired combustion with regard to temperature, heat flux distribution, and pollutant emissions. While most studies provide information on the impacts of O2 concentration in the feed gas, the impact of burner configuration and operating settings on oxy-coal combustion have been investigated by only a handful of studies. The present study addresses the impact of oxy-fired conditions on the chemistry and dynamics of pulverized coal flames generated by a staged feed-gas burner operating with pre-dried lignite. Investigations were carried out in a newly constructed test facility where the combustion takes place in a horizontal up-fired furnace with a rated capacity of 0.40 MWth. Since the focus of this work is on adapting oxy-fuel combustion techniques to existing furnaces, great emphasis is placed on maintaining flame temperatures and heat transfer similar to that of conventional air combustion. The strategy adopted to investigate the impacts of burner settings is divided into theoretical and experimental investigations. In the theoretical study, the combustion-related parameters are calculated based on thermodynamic balances and act as a background for the definition of some important operating settings. Non-reacting flow simulations which include the burner and part of the furnace are performed using a CFD commercial code aimed at a qualitative evaluation of feed gas distribution and swirl strength on the flow pattern formed in the near burner region. These predictions assist in the interpretation of the experimental data and in the calculation of the swirl number at the exit of the burner. During the experimental investigations, the characteristics of diffusion flames were first investigated in a parametric study to evaluate the impact of secondary swirl numbers at three levels and secondary/tertiary flow ratios on the overall combustion performance. The second part of the test program involved detailed in-flame measurements for selected flames. Measurements of local gas temperature, gas species concentrations, and radiative heat flux were performed with standard water-cooled probes with special focus on the near burner region. Theoretical and experimental studies are also carried out under air-fired conditions and used as a benchmark throughout this study. The overall O2 fraction upstream of the burner was kept at 31 vol% and was defined with basis on a similar adiabatic flame temperature as air-firing. Flame stabilization was shown to be strongly dependent on the O2 fraction of the primary stream, feed gas distribution between the secondary and tertiary registers, and strength of the secondary swirl. Type-1 flames operating at a stoichiometric ratio of 1.17 were generated under air-fired and oxy-fired conditions and investigated in detail. Detailed flow pattern and flame structure studies show evidence of radial flame stratification consistent with gradual O2 admixing to the central fuel jet. Increasing the swirl number and the secondary/tertiary flow ratio enhances the mixing of coal particles and increases the temperatures close to burner. Much lower temperatures on the flame axis are observed under oxy-fired conditions. In the same region, higher CO concentrations were also observed, possibly as a result of CO2 dissociation and/or gasification reactions by water vapor and CO2 which contribute to lower temperatures. Very low CO concentration at the furnace exit and high particle burnout indicate that oxy-fired conditions are not an obstacle to achieving a high combustion efficiency for type-1 flames. Although SO2 concentrations were higher under oxy-fired conditions, the emission rates were very similar, indicating that SO2 emissions are exclusively dependent on the sulfur content of the coal. Experimental data obtained from the parametric study and in-flame measurements suggest great potential for NO abatement through flame aerodynamics for oxy-coal combustion. The experiments demonstrate that feed gas staging in a burner is an effective technique for improving the flame stratification in fuel-rich and fuel-lean zones. In particular, a combination of high swirl and high secondary/tertiary flow ratio results in significant NO reduction.
This thesis addresses fundamental physical processes which take place at the surface region of a target during and after the interaction with ultra-short laser pulses. The general goal is to bring together different phenomena and discuss the non-equilibrium nature of the interaction of femtosecond laser pulses (tp < 100 fs) with various materials, in particular dielectrics and semiconductors. Different experiments, using various techniques, are designed to explore the basic mechanisms of laser ionization, defect creation, electron-lattice energetic transfer, charged particles desorption, optical breakdown, phase transformations and surface morphological changes. Such processes are shown to depend strongly on the laser intensity. Thus, they are analyzed for intensities over four orders of magnitude (10^11-10^14 W/cm2), around the surface optical breakdown (damage) threshold intensity. First, experimental studies using time-of-flight mass spectrometry indicate that non-resonant intense ultra-short laser pulses can efficiently ionize a dielectric (semiconducting) material leading to emission of electrons as well as charged particles, i.e. atomic ions and large clusters, and neutral particles. Under these irradiation conditions, the ionization processes can be at best described by multiphoton ionization and ionization at defects sites. The structural defects provide the means for an increased positive ion desorption rate. A multiple pulse incubation effect in the ion yield can be well related with the reduction of the multi-pulse damage threshold with increasing intensity. Following the initial electron excitation and emission, positive ions are released from the surface in a substantial amount with high ion velocities indicative of a localized microscopic electrostatic expulsion. With increasing intensity, the amount of ions gets larger and larger and their velocity distribution exhibits a bimodal structure. Also, in these conditions, negative ions are detected. The ion desorption can arise from a combination of a localized electrostatic repulsion (macroscopic Coulomb explosion) and a thermal ‘explosive’ mechanism. The later becomes more important with increasing intensity. The very fast energy input and particle emission result in a transient perturbation and deformation of the target lattice. Using pump-probe experiments the temporal evolution of lattice dynamics can be analyzed upon single-pulse excitation for many different target materials. This deformation is indicated to be a material characteristic. It is associated with the generation of transient defects in dielectrics or fast phase transitions in semiconductors and metals. Therefore, it could well give estimates of lifetime of transient defect states or electron-phonon relaxation times.At last the surface morphology after ablation is analyzed, with emphasis on the laser-induced surface periodic patterns (ripples). The patterns observed appear to be very different from the ‘classical’ ripples formed after long pulse ablation. They can have periods much smaller than the incident wavelength and are rather insensitive to the variation of the laser wavelength and angle of incidence. We show that control factors are laser beam polarization and the irradiation dose. Additionally, the patterns exhibit features pointing toward a chaotic origin. Their possible formation mechanism is likely linked with the non-equilibrium nature of the interaction.
Implementation of End-of-Life Vehicle’s Recycling for Developing Countries: Case Study, Mexico
(2008)
Currently, the Directive 2000/53/EC regulates the ELV management in 27 countries in Europe, and for the forthcoming years, more accession countries are foreseen. Since, the international nature of automotive industry, the Directive has affected industries beyond the EU. Hence, countries with important national-based automotive industry are moving towards the accomplishment of this legislation, in order to keep their competitiveness in European markets. The ELV chain in the EU is a complex system, which involves several commercial relationships between different sectors. The generation of ELV in the EU-15 was around 11.4 million units in 2005. The total number of ELV generated, considering the accessing countries, is still unknown. The number of treated ELV in the EU-15 was 7.7 million units. There are some obstacles to be overcome by ELV management already in implementation in the EU. The main difficulties are related to the reluctance of car-manufacture industry to implement Directive’s provisions related to: ban of use of specific substances in automotive applications, and about recycling quotas. Another obstacle is the export of ELV from the EU, which represents a loss in input material for the system. The case of the USA, regarding the ELV management, has very different connotations than the implemented system in the EU. The current ELV management in the USA does not have specific regulations regarding the collection and recycling of ELV. The structure of the ELV chain in the USA is similar to its counterpart in the EU. The main difference lies in dismantling and post-shredder sectors. The 80% of dismantling industry is composed of salvage/scrap yards performing no-standardized operations, and the remaining 20% is represented by high value parts dismantlers. One special feature of the system is the classification of ASR as no-hazardous waste which generates almost no incentives for further treatment. The current system of ELV management in the USA works with relative efficiency. However, there are still items to be improved, e.g. poor dismantling practices in a big number of dismantling facilities (scrap yards), use of hazardous materials in car-manufacture, disposal of ASR as non-hazardous waste, scrap tyres, etc. The ELV problem has different connotation in developing countries like Mexico, than in industrialized countries. Problems, like illegal introduction of used cars from the USA to Mexico and poor practices in the management of ELV, affect the Mexican economy, environment and society. In Mexico, there exists no specific legislation to regulate the Management of ELV. This kind of product, at its End-of-Life stage and wastes generated by its treatment, has been ruled by general laws before the year 2004. More recently a semi-specific law has been addressed to solid wastes, the LGPGIR. The structure of ELV chain in Mexico is similar to its counterpart in the USA and the EU, except for an additional stage. The present work depicts the available information about the number of Mexican operators, at every stage of ELV management. The described evidence presents a deficient management of ELV in Mexico. The current management allows a maximum recycling rate of 75%, which mainly corresponds to the ferrous fraction content in vehicles which enters to the management system. The present work develops a proposal for a suitable system to manage End-of-Life Vehicles (ELV) in a developing country, case study Mexico. This, is divided in three main parts. As a first step, the proposal estimates the future numbers of ELV generated in Mexico, which are estimated in a current ELV generation of around 687,000 vehicles by 2007, and by 2020 in the range of 1.1 to 1.3 million units per year. The second step is to propose a structure for the ELV chain in Mexico. The proposed structure describes the recommended operations, equipment and facilities’ configuration at every stage of the management. The third step of the proposal is the configuration of strategic facility network at every stage of ELV management in Mexico. The system is configured under assumption of three different scenarios, i.e. 100%, 90% and 75% of covered demand for ELV management. The algorithm is identified for this specific problem as a Fixed Charge Facility Location Problem. The algorithm is solved through Facility Location Software SITATION©. The results show the optimal number of facilities at every stage of the management, to cover the demand for ELV management considered in the different scenarios. The fourth part is to propose a model to finance the ELV management in Mexico. The main features of this scheme are explained, as well as its advantages, disadvantages and incentives thought to be triggered into the Mexican ELV chain.
Der Missbrauchsskandal der Jahre 2010/11 rückte das Thema des Schutzes von Kindern und Jugendlichen vor sexualisierter Gewalt in pädagogischen Kontexten erstmals mit nachhaltiger Empörung in den öffentlichen wie fachlichen Fokus. Die gesellschaftliche Empörung war groß, pädagogische Fachkräfte fühlten sich fortan nicht selten unter Generalverdacht gestellt und zahlreiche Organisationen waren nun innerhalb kürzester Zeit bereit, in Orientierung an den Leitlinien des Runden Tisches Sexueller Kindesmissbrauch, Konzepte für den Schutz vor sexualisierter Gewalt in ihren pädagogischen Einrichtungen zu implementieren. Ein Bestandteil dieser Schutzkonzepte soll die freiwillige Selbstverpflichtungserklärung (Ehrenkodex, Verhaltenskodex etc.) sein. In der Folge legten zahlreiche Organisationen ihren Fachkräften und Mitarbeitenden (individuelle) Selbstverpflichtungen vor, um diese auf den Schutz von Kindern und Jugendlichen vor sexualisierter Gewalt in ihrer pädagogischen Arbeit zu verpflichten. Auch die Organisationen verpflichteten sich mit einer (institutionellen) Selbstverpflichtung auf den Schutz vor sexualisierter Gewalt in ihren pädagogischen Einrichtungen und unterzeichneten eine Kooperationsvereinbarung mit dem/der Unabhängigen Beauftragten für Fragen des sexuellen Kindesmissbrauchs. Die Frage nach der Wirkung dieser individuellen und institutionellen Selbstverpflichtung für den Schutz vor sexualisierter Gewalt an Kindern und Jugendlichen in pädagogischen Kontexten wurde in der vorliegenden Arbeit wissenschaftlich untersucht und beantwortet. Um die Gesamtforschungsfrage (differenziert in zehn Forschungs- und 32 Interviewfragen) beantworten zu können, wurden Expert*innen-Interviews mit pädagogischen Fachkräften und Mitarbeitenden geführt und die generierten Antworten inhaltlich-strukturanalytisch sowie verstehend-interpretativ bearbeitet. So ging es in der Ausdifferenzierung der Gesamtforschungsfrage unter anderem um Fragen nach der gemeinsamen Erarbeitung von Werten und Normen für den Schutz vor sexualisierter Gewalt in pädagogischen Kontexten oder auch den Einfluss und die Bedeutung der Selbstverpflichtung im Sinne von (sozialer) Kontrolle. Dabei bezieht die Autorin die individuelle Selbstverpflichtung zum einen auf die Perspektive sozial professionell Handelnder und zum anderen auf die Perspektive potentieller Täter*innen in pädagogischen Handlungsfeldern. Im Ergebnis und mit Bezug auf letztere Perspektive entwickelt die Autorin das System partizipativer Kontrolle und beschreibt neben der Wirkung auch die Voraussetzungen, unter denen eine individuelle Selbstverpflichtung in der pädagogischen Praxis den Schutz von Kindern und Jugendlichen vor sexualisierter Gewalt bewirken und wie diese damit auf potentielle Täter*innen wirken kann. Die Wirkung und das Wirksamwerden der Selbstverpflichtung bezogen auf die Perspektive sozial professionell und ehrenamtlich Handelnder entwickelt die Autorin entlang der Professionalisierung pädagogischen Handelns.
Approaches to restore post-mining areas should provide sustainable solutions for recovering biodiversity and ecosystem services in regions experiencing massive deforestation. Key components that are impacted by surface mining activities and that restoration intervention should therefore target are biodiversity attributes and ecosystem service provisioning. The consequences of restoration decisions in post-mining areas in the Afrotropical region (here Ghana) remain understudied. To this end, l assessed levels of soil properties, biodiversity and ecosystem service in a post-mining area after two decades of active forest restoration by comparing them to attributes of the surrounding dominant land-use types. l hypothesized that (i) the interventions applied to restore and manage a post-mining area improve ecosystem attributes beyond conditions observed in the alternative dominant land-use types and even reaching levels comparable to reference forest (Chapter III), (ii) soil conditions and the functional structure of tree communities drive ecosystem functions and multifunctionality, with highest multifunctionality levels in the restored and natural forests (Chapter IV), (iii) the structure of tree communities coupled with pronounced climatic seasonality support a higher number of arthropods and arthropod functional groups particularly in the wet season and in structurally heterogeneous land-use types (Chapter V), and (iv) active forest restoration enhances the levels of ecosystem service provision similar to the reference forest with possible trade-offs or synergies among individual ecosystem services across forest types (Chapter VI). Chapter I provides an introduction to deforestation, and further highlights global and national initiatives, including active forest restoration, to reverse or minimize the impacts of tropical deforestation. Chapter II details the methodological approaches applied for sampling. Chapter III focussed on soil properties in addition to below and above-ground biomass of trees. The characteristic soil attributes for the restored forest were not significantly different from those in the reference forest, except for bulk density and base saturation, but differed significantly from attributes in all other land-use types. Chapter IV focussed on how the functional structure of tree communities affects the provision of ecosystem services. For functional composition, both the leaf economic spectrum and the seed mass dimensions separated different land-use types. Chapter V addresses the research question on how post-mining restoration affects arthropod communities. Communities of ground-active arthropods differed significantly between land-use types depending on the season. By quantifying the various ecosystem attributes in the field and transforming them into ecosystem service proxies, l could primarily identify synergies with no apparent trade-off between ecosystem services across the forest land-use types (Chapter VI).
This thesis focuses on the deposition of thin TiO₂ films on p-type Si using atomic layer deposition (ALD) technique, on the study of the electronic proprieties of the grown films and on the electrochemical characterization of TiO₂/Si photoelectrodes. The deposition parameters, electronic properties and electrochemical performance and stability of the TiO₂/Si samples are correlated.
The ALD technique is used to deposit TiO₂ with two different precursors namely Titanium isopropoxide and Titanium methoxide onto Si substrates. Laboratory as well as synchrotron based X-ray spectroscopy techniques are used to characterize these films. The growth quality of the TiO₂ ALD films is determined by analyzing X-Ray photoelectron spectroscopy (XPS) data in terms of stoichiometry, defect states and Ti³⁺:Ti⁴⁺ ratios. The ALD technique was modified with different heating arrangements to obtain various polymorphs of TiO₂.
The ALD and anatase TiO₂ films are characterized using synchrotron radiation to study their electronic properties and these films are compared with single crystal rutile TiO₂. X-ray absorption spectroscopy (XAS) and resonant photoelectron spectroscopy (res-PES) measurements are performed with synchrotron radiation. XAS measurements are used to determine the polymorphs as well as the electronic structure of TiO₂ Res-PES measurements are conducted at the O1s and Ti2p edges to study multiple hole Auger decay processes and polaronic and charge transfer states as well as to determine the electronic band gap of the TiO₂ layers. One of the main findings of this thesis is the determination of the partial density of states (pDOS) of O and Ti in the conduction and valence band. The combination of the pDOS and the band edge positions obtained from res-PES measurements are used to calculate the charge neutrality level of the TiO₂ polymorphs.
The photoelectrochemical measurements are conducted on bare-Si and TiO₂/Si photoelectrodes. The electrochemical performance of these photoelectrodes is studied in electrolytes having pH values ranging from 1 to 13. The deposition of TiO₂ on Si enhances the photoelectrochemical performance of the Si photoelectrode. The TiO₂ increases the stability of the photoelectrode in all electrochemical media over 12 hours of experimental condition. Moreover, it is also observed that the TiO₂/Si photoelectrode is less responsive to the pH value of the electrolyte. The electrochemical findings are explained on the basis of the electronic properties of the TiO₂ layer. The electronic band gap obtained from spectroscopic measurement and the photoelectrochemical measurements are used to explain the performance and stability of the TiO₂/Si photoelectrodes. The thesis also addresses the stability of Si microstructured photoelectrodes (SiMPs) prepared by an electrochemical method. The stability of the SiMPs deteriorates more rapidly than that one of the planar Si photoelectrode. However, using a protective ALD TiO₂ layer on these SiMPs the overall performance is even more enhanced than on the TiO₂/planar Si system.