This paper shows the study carried out in a doctoral thesis about windmills in south-east Spain, in the area of Campo de Níjar in the province of Almeria. It intends to pay homage to Spanish windmills as a way of commemorating the fourth centenary of the masterwork of Spanish Literature, ‘Don Quixote’ in which the silhouette of the windmill is a pervading symbol.Wheat milling has been an important factor in the socio-economic development of rural Spain for centuries. The type of mill used depended on the energy resources available, wind or water. In the Campo de Níjar (Almeria, Andalusia, Spain), wind is the principal energy source, and therefore, windmills were widely used, as in other areas of Spain. In this paper, we study the technological conditions of these old windmills, we carry out a wind evaluation of the area, and we calculate the power and momentum of these windmills with a discussion of the results found. 相似文献
The cone photoreceptor mosaic of the living human eye has in a limited number of cases been imaged without the use of wavefront-correction techniques. To accomplish this, the directionality of the photoreceptors, as manifested by their waveguiding properties, may be used to advantage. In the present paper we provide a model of our recently proposed directional light scanning laser ophthalmoscope [Opt. Lett. 29, 968 (2004)] together with a detailed numerical analysis of the device. The outcome is compared with experimental results. 相似文献
Summary: Poly(sulfone of Bisphenol A) (PSU) based blends were obtained by melt blending PSU with up to 15 wt.‐% poly(ethylene‐octene) either modified with maleic anhydride (mPEO) or not (PEO). The dispersed particle size was small and similar in blends with PEO or mPEO. These facts indicated respectively that the interfacial tension was low and the lack of compatibilizing effect of mPEO. Some preferential presence of PEO in the outer surface of the specimens was observed, and was attributed to the large viscosity difference between the two components of the blends. This had no effect on the modulus of elasticity, but speeded up both the yield stress and ductility decreases at rubber contents above 3.25 wt.‐%. However, despite the immiscibility of the components, and thanks to the small particle size of the blends, super‐toughness was attained in the unmodified PSU/PEO blends. This was at PEO contents (3.25 wt.‐%) at which the modulus, yield stress and ductility of the blends were almost as good as those of pure PSU. It appeared that a change of the chemical nature of the rubber did not influence by itself super‐toughness, unless it was accompanied by either a morphological or adhesion change.
Impact strength of PSU‐based blends vs. PEO (○) or mPEO (?) content. 相似文献
A new multipurpose genetic algorithm, based on Pareto optimality, is proposed to design logical topologies for wavelength-routed
optical networks with the aim of minimizing both the congestion and the end-to-end delay. Simulation results show its efficiency
when compared with other previously proposed algorithms, achieving in most cases optimal or near-optimal solutions, and in
less time than other methods. Moreover, since the algorithm relies on Pareto optimality, not only does it obtain a single
logical topology but a set of them, so that the network designer can easily select the most appropriate one according to the
current network requirements. 相似文献
A new method to design logical topologies based on genetic algorithms is presented. Not only does the algorithm determine
which nodes should be connected by means of lightpaths with the aim of minimizing congestion, but it also solves the routing
and wavelength assignment problem. In this way, the algorithm guarantees that the logical topology obtained can be embedded
in the optical network subject to the available set of resources. The algorithm is effective in terms of both congestion and
fairness. For instance, when compared with other work, the congestion is significantly reduced (from 20% to 75% depending
on the matrix of traffic considered), and the fairness, when evaluated in terms of the Jain index, is generally higher than
0.94. Moreover, the algorithm brings advantages when employed in dynamic scenarios where the logical topology is frequently
reconfigured, as it is fast and, in contrast to other algorithms previously proposed, the calculation process can be stopped
at any time (if required) in order to give the best virtual topology found up to the moment.
An end-to-end system to automate the well-known Tanner--Whitehouse (TW3) clinical procedure to estimate the skeletal age in childhood is proposed. The system comprises the detailed analysis of the two most important bones in TW3: the radius and ulna wrist bones. First, a modified version of an adaptive clustering segmentation algorithm is presented to properly semi-automatically segment the contour of the bones. Second, up to 89 features are defined and extracted from bone contours and gray scale information inside the contour, followed by some well-founded feature selection mathematical criteria, based on the ideas of maximizing the classes' separability. Third, bone age is estimated with the help of a Generalized Softmax Perceptron (GSP) neural network (NN) that, after supervised learning and optimal complexity estimation via the application of the recently developed Posterior Probability Model Selection (PPMS) algorithm, is able to accurately predict the different development stages in both radius and ulna from which and with the help of the TW3 methodology, we are able to conveniently score and estimate the bone age of a patient in years, in what can be understood as a multiple-class (multiple stages) pattern recognition approach with posterior probability estimation. Finally, numerical results are presented to evaluate the system performance in predicting the bone stages and the final patient bone age over a private hand image database, with the help of the pediatricians and the radiologists expert diagnoses. 相似文献
BACKGROUND: In Equatorial Guinea, as a result of the recent growth of the oil industry, there is an opportunity to address important public health problems through public and private initiatives. To propose effective nutrition and public health strategies, it is important first to have reliable information on the nutritional status of the population and the underlying factors affecting it. OBJECTIVE: To assess the nutritional status and the prevalence of anemia among Equatoguinean children in a nationally representative sample and to identify the risk factors associated with the nutritional problems detected. METHODS: The study was a cross-sectional survey using a multistaged, stratified, cluster-selected sample. The survey included a sociodemographic, health, and dietary questionnaire and measurement of hematocrit and anthropometric features, from which nutritional indicators based on the National Center for Health Statistics (NCHS) reference and the World Health Organization (WHO) standards were calculated. Logistic regression models were used for the multivariate analysis. A total of 552 children aged 0 to 60 months were surveyed. RESULTS: The overall prevalence of stunting (< -2 height-for-age z-scores [HAZ]) was 29.7% based on the NCHS reference and 35.2% based on WHO standards; the risk factors associated with stunting were age (p < .0001), low socioeconomic status (p = .01), and fishing by a member of the household (p = .003) The prevalence of mild anemia (hemoglobin < 110 g/L) was 69.3%, and that of moderate or severe anemia (hemoglobin < 80 g/L) was 8.3%. The only significant risk factor associated with moderate to severe anemia was low household socioeducational level (p = .01). CONCLUSIONS: Stunting and anemia are public health problems in Equatorial Guinea. Integrated strategies, including fighting poverty and improving maternal education, should be undertaken. 相似文献