The coupled theory of micropolar thermoelastic diffusion

The general equations of motion and constitutive equations are derived for a general homogeneous anisotropic medium with a microstructure, taking into account the effects of heat and diffusion. We establish a reciprocal relation, which involves two thermoelastic diffusion processes at different instants. We show that this relation can be used to obtain reciprocity, uniqueness and continuous dependence theorems. The reciprocity theorem avoids both the use of the Laplace transform and the incorporation of initial conditions into the equations of motion. The uniqueness theorem is derived without the positive definiteness assumption on the elastic, conductivity and diffusion tensors. We prove also that the reciprocal relation leads to a continuous dependence theorem studied on external body loads. Finally we prove the existence of a generalized solution by means of the semigroup of linear operators theory.     

Exploratory investigation on mechanical anchors for connecting SMA bars to steel or FRP bars

Using superelastic shape memory alloys (SMAs) as reinforcing bars in concrete structures proved to have a great potential in seismic areas because of its recentering capability. However, using them in an entire structure is generally not economically feasible due to their high cost. Therefore, it is more practical to limit their use to the plastic hinge zones, while regular steel can be used in the other regions of the structure. Connections between SMA and steel are critical, and need to be strong enough to transfer the full force from SMA bars to steel bars. Various mechanical couplers are available in the market to splice bars in reinforced concrete (RC) structures, each of which has several advantages and disadvantages. The efficiency of these couplers for connecting steel bars is tested and reported in this paper. Since these couplers are intended for connecting steel bars only, another experimental investigation has been performed to determine the suitability of these couplers for connecting SMA with steel bars. Commercially available screw-lock couplers are found to be unsuitable for connecting SMA to steel bars. An existing coupler has been modified for SMA–steel splicing to allow SMA bars to achieve their full superelastic strain. Additional tests have also been performed for connecting FRP bars to SMA bars. A new generation mechanical-adhesive type coupler has been developed for splicing FRP to SMA bars.     

Analysis of impact of daylight time savings on energy use of buildings in Kuwait

In this paper, a detailed simulation-based analysis is conducted to assess the impact of adopting Daylight Saving Time (DST) on the electrical energy use and peak demand in Kuwait. The analysis focused on the impact of DST in the building sector since it represents 90% of electrical energy usage of Kuwait.     

Power transformer fault diagnosis based on dissolved gas analysis by support vector machine

This paper presents an intelligent fault classification approach to power transformer dissolved gas analysis (DGA). Support vector machine (SVM) is powerful for the problem with small sampling (small amounts of training data), nonlinear and high dimension (large amounts of input data). The standard IEC 60599 proposes two DGA methods which are the ratios and graphical representation. According the experimental data, for the same input data, these two methods give two different faults diagnosis results, what brings us to a problem. This paper investigates a novel extension method which consists in elaborating an input vector establishes by the combination of ratios and graphical representation to resolve this problem. SVM is applied to establish the power transformers faults classification and to choose the most appropriate gas signature between the DGA traditional methods and a novel extension method. The experimental data from Tunisian Company of Electricity and Gas (STEG) is used to illustrate the performance of proposed SVM models. Then, the multi-layer SVM classifier is trained with the training samples. Finally, the normal state and the six fault types of transformers are identified by the trained classifier. In comparison to the results obtained from the SVM, the proposed DGA method has been shown to possess superior performance in identifying the transformer fault type. The SVM approach is compared with other AI techniques (fuzzy logic, MLP and RBF neural network); the proposed method gives a good performance for transformers fault diagnosis. The test results indicate that the novel extension method and the SVM approach can significantly improve the diagnosis accuracies for power transformer fault classification.     

Qualitative Aspects in the Coupled Theory of Thermoelastic Diffusion

In this paper we derive some qualitative results of the coupled theory of thermoelastic diffusion for anisotropic media. We establish a reciprocity relation, which involves two thermoelastic diffusion processes at different instants. We show that this relation can be used to obtain reciprocity, uniqueness and continuous dependence theorems. The reciprocity theorem avoids both the use of the Laplace transform and the incorporation of initial conditions into the equations of motion. The uniqueness theorem is derived without the positive definiteness assumption on the elastic, conductivity and diffusion tensors. We prove also that the reciprocal relation leads to a continuous dependence theorem studied on external body loads. Finally, we prove the existence of a generalized solution by means of the semigroup of linear operators theory.     

Theory of Generalized Micropolar Thermoelastic Diffusion Under Lord–Shulman Model

The general equations of motion and constitutive equations, based on the theory of Lord–Shulman with one relaxation time, are derived for a general homogeneous anisotropic medium with a microstructure, taking into account the effects of heat and diffusion. A variational principle for the governing equations is obtained. Then we show that the variational principle can be used to obtain a uniqueness theorem under suitable conditions. A reciprocity theorem for these equations is given. The obtained results are valid for some special cases which can be deduced from our generalized model.     

Time modeling in high-speed machining of mold pocket

Numerical control milling (NCM) at high speed is the most used machining process in the manufacture of molds because it offers high productivity and workpiece surface quality. The aim of this work is to establish a methodology to evaluate the rough machining time, during high speed milling. In pocket machining, a 2.5D milling has been considered. The proposed approach considers the roughing cutting time as the ratio of the pocket volume by the removed material rate. The pocket is divided into volumes distributed according to the real radial depth. Since the radial depth varies during machining, the removed material rate is not constant. In this paper, an experimental study is carried out to validate models of machining time calculation. The obtained results show that the proposed method offers fast and easy calculation of the machining time of pocket roughing.     

Nutritional composition of Zizyphus lotus L. seeds

BACKGROUND: Zizyphus lotus seeds are an unutilized source of vegetable oil and protein and nothing has been reported on their physicochemical characteristics which would indicate the potential uses of these seeds. RESULTS: The percentage composition of the Zizyphus lotus seeds is (on a dry‐weight basis): ash 1.05%, oil 32.92%, protein 19.11%, total carbohydrate 40.87% and moisture 6.05%. Calcium, potassium and magnesium constitute the major minerals of Zizyphus lotus seeds. The seed proteins are rich in threonine, glutamic acid, leucine, arginine and aspartic acid (26.73%, 17.28%, 13.11%, 9.47% and 7.76%, respectively). The main fatty acids of the oil are oleic (61.93%), linoleic (18.31%) and palmitic (9.14%) acids. Glycerol trioleate (OOO; O: oleic acid) was the most abundant triacylglycerol, representing 26.48% of the total triacyglycerols. β‐Tocopherol was the major tocopherol (130.47 mg 100 g^?1). This oil was rich in Δ7‐campestrol and β‐sitosterol (147.82 and 82.10 mg 100 g^?1 oil), respectively. CONCLUSION: Zizyphus lotus seeds are rich in fat and protein which are of potential industrial significance. In addition, Zizyphus lotus L. seed oil contained many bioactive compounds. This fact is of great economic interest owing to several applications of Zizyphus lotus L. seeds in the food, cosmetics and medicinal industries. Copyright © 2011 Society of Chemical Industry     

Phototransformation of the insecticide fipronil: identification of novel photoproducts and evidence for an alternative pathway of photodegradation

Fipronil is a recently discovered insecticide of the phenylpyrazole series. It has a highly selective biochemical mode of action, which has led to its use in a large number of important agronomical, household, and veterinary applications. Previous studies have shown that, during exposure to light, fipronil is converted into a desulfurated derivative (desulfinyl-fipronil), which has slightly reduced insecticidal activity. In this study, the photodegradation of fipronil was studied in solution at low light intensities (sunlight or UV lamp). In addition to desulfinyl-fipronil, a large number of minor photoproducts were observed, including diversely substituted phenylpyrazole derivatives and aniline derivatives that had lost the pyrazole ring. Desulfinylfipronil itself was shown to be relatively stable under both UV light and sunlight, with only limited changes occurring in the substitution of the aromatic ring. Since this compound accumulated to levels corresponding to only 30-55% of the amount of fipronil degraded, it was concluded that one or more alternative pathways of photodegradation must be operating. On the basis of the structurally identified photoproducts, it is proposed that fipronil photodegradation occurs via at least two distinct pathways, one of which involves desulfuration at the 4-position of the pyrazole ring giving the desulfinyl derivative and the other of which involves a different modification of the 4-substituent, leading to cleavage of the pyrazole ring and the formation of aniline derivatives. The latter compounds do not accumulate to high levels and may, therefore, be degraded further. The ecological significance of these results is discussed, particularly with regard to the insecticidal activity of the photoproducts.