Divergent principles in third world rural planning: a case study on impoldering

Third World rural planning involves the transfer of First World technologies to the socially and ecologically vulnerable tropical environment. This transfer is guided by normative, “ideological” views concerning social and environmental issues which often remain implicit. To uncover these views, a content analysis of a series of papers has been carried out, focused on impoldering as a type of project with far reaching social and environmental impacts. Three types of “ideologies” could be distinguished, which have been labelled as sociocratic, eco‐sociocratic and technocratic. They differentiate significantly with regard to (1) values attached to ecological and cultural systems, (2) preferred pace and scale of projects, (3) envisaged project feasibility, (4) the range of feasible alternatives, as well as (5) the institutional background of their adherents. The latter separation, however, is not complete. This may stimulate the growth of insight in the normative background of the seemingly objective rationality of project design.     

Multiprocessor modeling of parallel Particle Swarm Optimization applied to nuclear engineering problems

Particle Swarm Optimization (PSO) is a population-based metaheuristic (PBM), in which solution candidates evolve through simulation of a simplified social adaptation model. Putting together robustness, efficiency and simplicity, PSO has gained great popularity. Many successful applications of PSO are reported, in which PSO demonstrated to have advantages over other well-established PBM. However, computational costs are still a great constraint for PSO, as well as for all other PBMs, especially in optimization problems with time consuming objective functions. To overcome such difficulty, parallel computation has been used. The default advantage of parallel PSO (PPSO) is the reduction of computational time. Master-slave approaches, exploring this characteristic are the most investigated. However, much more should be expected. It is known that PSO may be improved by more elaborated neighborhood topologies. Hence, in this work, we develop several different PPSO algorithms exploring the advantages of enhanced neighborhood topologies implemented by communication strategies in multiprocessor architectures. The proposed PPSOs have been applied to two complex and time consuming nuclear engineering problems: i) reactor core design (CD) and ii) fuel reload (FR) optimization. After exhaustive experiments, it has been concluded that: i) PPSO still improves solutions after many thousands of iterations, making prohibitive the efficient use of serial (non-parallel) PSO in such kind of real-world problems and ii) PPSO with more elaborated communication strategies demonstrated to be more efficient and robust than the master-slave model. Advantages and peculiarities of each model are carefully discussed in this work.     

Einfluss einer gezielt aufgeprägten Mikrogeometriestreuung auf das Anregungsverhalten von Kegelradverzahnungen

In the design process of transmissions, one major criterion is the resulting noise emission of the powertrain due to the gear excitation. Within the past years, a lot of investigations have shown that the noise emission can be correlated to the quasi-static transmission error. Therefore, the transmission error can be used as a characteristic value for quality assurance by experimental inspections as well as for a tooth contact analysis in the design process.The noise behavior of gearboxes is mainly caused by the excitation in the tooth mesh. The standardized design and calculation methods for gears concentrate on the reduction of the excitation level. But often the physical sound characteristics do not fit in with the human noise perception. Thus gear design rules are required that are able to rate the excitation according to the perception.The effect of the targeted topography scatter generally described is the reduction of the gear mesh amplitudes with an increase of the background noise. The objective of the report is to develop an understanding of the influence of different micro geometry scatters on the excitation behavior.Finally, it is the aim to design an aurally-accurate micro geometry scattering for the optimization of ground bevel gears in terms of tonality reduction and increased background noise. By means of a variant calculation and weighted target variables, psychoacoustic optimized micro geometry scattering is designed. At the same time, attention is also focused on a simple production of mixed topographies.     

Fluid-to-fluid modeling of supercritical water loops for stability analysis

The use of supercritical water as coolant/moderator may induce oscillations in the supercritical light water reactor similar to the density wave oscillations observed in boiling water reactors (BWRs). In order to experimentally investigate the stability of supercritical reactors, a fluid-to-fluid downscaled facility is proposed. It is found that with an appropriate mixture of refrigerants R-125 and R-32, the dimensionless enthalpy and density of the supercritical water can be accurately matched for all relevant operational conditions of the reactor. Moreover, the inertia distribution, the friction factor distribution and the heat transfer mechanism are taken into account in the modeling. As a result of the proposed downscaling, the operational pressure, temperature and power are considerably smaller than those of a water-based system, which in turn helps reducing the construction and operational costs of a test facility. Finally, it is found that the often used modeling fluid supercritical CO₂ cannot accurately represent supercritical water at reactor conditions.     

Multidisciplinary Approach to Unravelling the Relative Contribution of Different Oxylipins in Indirect Defense of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

The oxylipin pathway is commonly involved in induced plant defenses, and is the main signal-transduction pathway induced by insect folivory. Herbivory induces the production of several oxylipins, and consequently alters the so-called ‘oxylipin signature’ in the plant. Jasmonic acid (JA), as well as pathway intermediates are known to induce plant defenses. Indirect defense against herbivorous insects comprises the production of herbivore-induced plant volatiles (HIPVs). To unravel the precise oxylipin signal-transduction underlying the production of HIPVs in Arabidopsis thaliana and the resulting attraction of parasitoid wasps, we used a multidisciplinary approach that includes molecular genetics, metabolite analysis, and behavioral analysis. Mutant plants affected in the jasmonate pathway (18:0 and/or 16:0 -oxylipin routes; mutants dde2-2, fad5, opr3) were studied to assess the effects of JA and its oxylipin intermediates 12-oxo-phytodienoate (OPDA) and dinor-OPDA (dnOPDA) on HIPV emission and parasitoid (Diadegma semiclausum) attraction. Interference with the production of the oxylipins JA and OPDA altered the emission of HIPVs, in particular terpenoids and the phenylpropanoid methyl salicylate, which affected parasitoid attraction. Our data show that the herbivore-induced attraction of parasitoid wasps to Arabidopsis plants depends on HIPVs that are induced through the 18:0 oxylipin-derivative JA. Furthermore, our study shows that the 16:0-oxylipin route towards dnOPDA does not play a role in HIPV induction, and that the role of 18:0 derived oxylipin-intermediates, such as OPDA, is either absent or limited.     

Thermal properties of new molybdenum oxyfluoride glasses

New oxyfluoride glasses were prepared in the form MoO₃-BaF₂-xRF where RF is alkali fluoride (LiF, NaF and mixed NaF–LiF) with x = 5, 10, 15, 20, 25, 30 and 35 mol%. The densities of the studied glasses were measured and the molar volumes were calculated. Thermal properties like glass transition temperature T _g, the onset of crystallization temperature T _x , crystallization temperature T _c and melting temperature T _m were determined by using the differential scanning calorimetry (DSC) technique and from which the glass stability S and the glass forming tendency K _g were calculated. Values of thermal expansion coefficient and specific heat C _p of the present glasses were also measured. All the above properties are correlated with composition alkali fluoride RF content and structure of the glass.     

Multimodal Video Indexing: A Review of the State-of-the-art

Efficient and effective handling of video documents depends on the availability of indexes. Manual indexing is unfeasible for large video collections. In this paper we survey several methods aiming at automating this time and resource consuming process. Good reviews on single modality based video indexing have appeared in literature. Effective indexing, however, requires a multimodal approach in which either the most appropriate modality is selected or the different modalities are used in collaborative fashion. Therefore, instead of separately treating the different information sources involved, and their specific algorithms, we focus on the similarities and differences between the modalities. To that end we put forward a unifying and multimodal framework, which views a video document from the perspective of its author. This framework forms the guiding principle for identifying index types, for which automatic methods are found in literature. It furthermore forms the basis for categorizing these different methods.     

Multiresolution Design of Aperture Operators

The design of an aperture operator is based on adequately constraining the spatial domain and the graylevel range in order to diminish the space of operators and, consequently, the estimation error. The design of a resolution constrained operator is based on adequately combining information from two or more different resolutions and has the same motivation, that is, diminish the space of operators to facilitate design. This paper joins these approaches and studies multiresolution design of aperture operators for grayscale images. Spatial resolution constraint, range resolution constraint and the combination of both constraints are characterized, and the error increase by using the constrained filter in place of the optimal unconstrained one is analyzed. Pyramidal multiresolution design involves applying the resolution constraint approach hierarchically, from the higher to the lower resolution space. These approaches are also characterized and their error increase analyzed. The system that has been implemented to design pyramidal multiresolution operators is described and has its complexity (memory and runtime) analyzed. Several simulations and two applications for deblurring are shown and compared to optimal linear filters. The results confirm the usefulness of the approach.     

Nanoparticle detachment: a possible link between macro- and nanotribology?

Although particle detachment is a common phenomenon associated with most tribological processes, it seldom occurs that each piece of elemental debris can be considered as the result of a single event. Such an association has been revealed by the systematic study of a specific system, where a pin of graphite is made to rub against thoroughly polished steel. While the discontinuous nature of the transfer film allows a quantitative assessment of the volume of transfer h _e to be made by 3D optical-profilometry, the linear dependence of the rate of particle detachment dh _e/dn (n=number of rubbing cycles) with the logarithm of sliding speed v strongly suggests the existence of a particular type of stick–slip, where each stick may lead to the detachment of a debris particle. The variations in size of these debris with environment as revealed by AFM, further suggest that the global rate of particle detachment is of the form: dh _e/dn=Nx _i , where N is the number of stick–slip events per rubbing cycle, x the proportion of stick events leading to a cohesive rupture, and _i the mean volume of an elemental particle. While this relation is apparently supported by most experimental results, its actual validation can only be made by experiments at the level of single (nanoscale) asperities, carried out under well-controlled experimental conditions.