Relativistic Coulomb wave functions in momentum space

Thirty-six 3-month-old female Wistar rats were labelled with a single intraperitoneal tetracycline injection. Twenty-four animals were subsequently ovariectomized, while the control group of 12 animals underwent sham operations. All animals received the basal Ewos R3 diet and half of the ovariectomized animals (n = 12) were given an additional 5% dietary xylitol supplementation. Three months later, following the collection of blood and urine, the animals were killed by decapitation. The tibiae were detached and prepared for chemical and other studies. The weight and density of the tibiae were measured. The right tibiae were dried and pulverized for chemical analysis of calcium, phosphorus and citric acid. The total inorganic fraction was determined by ashing the powdered bone. The left tibiae were cross-sectioned at the tibio-fibular junctions for the measurement of the width of periosteally formed bone, which was identified by tetracycline fluorescence. The examination of mineral content of bone was performed by scanning electron microscopy, using an electron probe microanalytic technique. The results indicate that the supplementation of the diet with 5% xylitol had a protective effect against the loss of bone mineral after ovariectomy in the rat. This was clearly seen in tibial density and in the inorganic fraction of the bone, and in the concentrations of bone Ca and phosphorus. Ovariectomy caused a doubling in periosteal bone formation relative to the controls, whereas the growth of the periosteally formed bone was somewhat reduced following xylitol supplementation as compared with ovariectomy alone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Investigation on thermal performance of glazed solar chimney walls

This paper reports investigation on the thermal performance of glazed solar chimney walls (GSCW) under the tropical climatic conditions of Thailand. The GSCW consisted of double glass panes with an air layer and openings located at the bottom (room side glass pane) and at the top (ambient side glass pane). A prototype of GSCW was integrated into the southern wall of a small room of 2.8 m³ volume. Its dimensions were as follows: 0.74 m height, 0.50 m width and 0.10 m air gap. The size of openings was 0.05 × 0.5 m². With a clear glass of 6 mm thickness, velocity field measurement indicated that the induced airflow rate was about 0.13–0.28 m³/s. The temperature difference between room and ambient was less than that with a single layer clear glass window. The reduction of daylight due to the double glass layer is negligible. Comparison between simulated and experimental results showed a reasonable agreement, therefore, the developed numerical model is valid and could be used as a tool for the design of GSCW.     

Investigation on generated power of thermoelectric roof solar collector

The aim of this paper was to conduct lab-scale investigation of a new roof design concept termed “the thermoelectric roof solar collector (TE-RSC)” for power generation using solar energy. The TE-RSC was composed of a transparent acrylic sheet, air gap, a copper plate, thermoelectric modules and a rectangular fin heat sink. The incident solar radiation heats up the copper plate so that a temperature difference is created between the TE module that generates a direct current. This current generated was used to run a fan for cooling the TE modules. The TE-RSC surface area was 0.0525 m² and 10 thermoelectric cooling modules (Tianjin Lantian model TEC1-12708) were used. Investigations were done by varying solar radiation, simulated by using a halogen lamp, between 400 and 1000 W/m².It was found that this new roof design can generate about 1.2 W under solar radiation intensity of about 800 W/m² at ambient temperature varying between 30 and 35 °C. The corresponding air velocity generated by the ventilation fan was about 1.7 m/s. Therefore, the proposed TE-RSC concept seems to be an interesting new alternative for various purposes such as power generation in remote areas, roof heat gain reduction and indoor ventilation of spaces.     

Theoretical and finite element studies of interfacial stresses in reinforced concrete beams strengthened by externally FRP laminates plate

The paper presents the results of an analytical and numerical solution for interfacial stresses in carbon fiber reinforced plastic (CFRP)–reinforced concrete (RC) hybrid beams studied by the finite element method. The analytical analysis is based on the deformation compatibility approach where both the shear and normal stresses are assumed to be invariant across the adhesive layer thickness. The adherend shear deformations are taken into account by assuming a parabolic shear stress through the thickness of both the concrete beam and the bonded plate. In numerical analysis, the mesh sensitivity test shows that the finite element results for interfacial stresses are not sensitive to the finite element mesh. The finite element analysis then is used to calculate the interfacial stress distribution and evaluate the effect of the structural parameters on the interfacial behavior. It is shown that both the normal and shear stresses at the interface are influenced by the material and geometry parameters of the composite beam. Numerical results from the present analysis are presented both to demonstrate the advantages of the present solution over existing ones and to illustrate the main characteristics of interfacial stress distributions. We can conclude that this research is helpful for the understanding the mechanical behavior of the interface and design of the FRP–RC hybrid structures.     

Investigation on the application of solar chimney for multi-storey buildings

This paper presents investigation on the use of solar chimney (SC) in high-rise building. To this end, two small scale models of a three storey building were built. The floor dimensions of each storey are 1.2 × 2 × 1 m. Solar chimneys were integrated into the south-faced walls of one unit whereas the other unit served as a reference. Two design configurations were considered including connected and non-connected solar chimney: The first is a tall SC with an inlet opening at each floor and one outlet opening at the third floor. While for the second, an inlet and outlet openings were installed at each floor. Data recorded included room temperature, air gap temperature and velocity of the induced air flow in the solar chimney.First, a comparison between the SC building models and a common model without openings (SC) demonstrated that multi-storey solar chimney is a good alternative. Room temperature of the solar chimney model was lower than the room temperature of the common model, depending on the floor level by up to 5 °C. Next comparison between the two SC configurations showed that the best configuration is that with an inlet opening at each floor and one outlet opening at the third floor as temperature difference between room and ambient was the lowest. Reasonable agreement between the experimental data and those derived from our mathematical model developed using electric analogies validated our model. Therefore multi-storey solar chimney is an interesting option and could be applied for hot climate like in Thailand to save energy and environment.     

The joint use of sequence features combination and modified weighted SVM for improving daily activity recognition

Two serious problems affecting the implementation of human activity recognition algorithms have been acknowledged. The first one corresponds to non-informative sequence features. The second is the class imbalance in the training data due to the fact that people do not spend the same amount of time on the different activities. To address these issues, we propose a new scheme based on a combination of principal component analysis, linear discriminant analysis (LDA) and the modified weighted support vector machines. First we added the most significant principal components to the set of features extracted using LDA. This work shows that a suitable sequence feature set combined with the modified WSVM based on our criterion classifier achieves good improvement and efficiency over the traditional used methods.     

Sizing of solar supplemented liquid and air heating systems for the treatment of vanilla

We study three different configurations of solar supplemented systems for simultaneous production of hot air and hot water needed during the processing of vanilla. Correlations for the monthly solar fraction versus two dimensionless factors defined in terms of physical characteristics of the system have been developed. Not only have the various solar systems been evaluated against each other from a techno-economic point of view, but we have also proposed correlations for the optimal system which directly relate the mass of the product to be dried with the area of the solar collector.     

Dynamic and multiphysic PEM electrolysis system modelling: A bond graph approach

Proton exchange membrane (PEM) electrolysis technology appears as a key technology in the development of hydrogen-energy market applications such as energy storage or fuel for mobility. Its coupling with renewable electrical sources involves some issues related to the intermittent operation of PEM electrolysis systems. Within this framework, modelling is an essential tool to understand these issues, provide a thorough analysis and suggest some design optimization. A bibliographic analysis was carried out to identify existing models. State of the art highlighted that, although it is critical for the conception of such systems, only a few models take into account the dynamic of the whole system including balance of plant. Therefore, in this paper a new dynamic and multiphysic model of a proton exchange membrane electrolysis system is presented. It was first developed under a graphical modelling formalism: the bond graphs (BG). Regarding dynamic and multiphysic modelling of complex systems, the BG have many advantages: it involves four levels of modelling using only one tool; it is a unified multiphysic approach; the parameters used have a physical meaning; the BG model can be refined very easily by adding new elements without having to start again the modelling process. Finally, because of its causal and structural properties, BG is suitable for modelling but also for control, sizing and diagnosis analysis. The model was then transcribed systematically into block diagrams in modular fashion for reutilisability of model libraries components. After a validation process, the model was proved to describe accurately the dynamic behaviour of a semi-industrial PEM electrolysis system (25 kW). The dynamic model can now be used to achieve some analyses through BG structural properties and simulations. Thus, it is a powerful tool to improve the design of PEM electrolysis systems powered by intermittent electrical sources.