Power Flattening in ARIES-RS Fusion Breeder Reactor Using Mixed Fuels

This study presents the possibility of the power flattening in the ARIES-RS breeder reactor using mixed (Th,U)C or (Th,U)N fuels. Two different types of mixing, namely, homogeneous mixing (HM) and linear mixing (LM) were used to investigate the uniformity of fission power distribution through the fuel zone. In HM, fraction of uranium content were kept constant in all rows of the fuel zone whereas, in LM the fraction of the uranium were linearly increased from the first to last fuel row in the fuel zone. Neutron transport calculations were performed with the aid of the SCALE4.3 system by solving the Boltzmann transport equation with the XSDRNPM code in 238 neutron groups and a S₈–P₃ approximation. Flat fission power distribution was maintained successfully for the blanket using linearly mixed fuels. However, the fission density profile was not uniform in the blanket with homogeneously mixed fuels. It decreased exponentially form the 1st to 10th fuel row.     

Biosorption of Acid Red P-2BX by lichens as low-cost biosorbents

The aim of this study is to examine the dye biosorption properties of lichen species called Cladonia convoluta and Evernia prunastri. Since lichens are extensively found in the environment, their suitability as a cheap adsorbent has been investigated in this study. The optimal parameters for textile dye biosorption were also determined. The dried lichen biomass showed better dye biosorption capacity than ash lichen biomass. C. convoluta had better dye biosorption capacity than E. prunastri. Dye biosorption rate was found as 71.41% at optimal conditions. This study concluded that C. convoluta was a successful and cheap biosorbent for treatment of water contaminated by Acid Red P-2BX dye.     

Alone or together: examples from history research

Individualistic nature of research in the humanities is a common fact, as well as the notion that boundaries in humanities are poorly defined. Using citation analysis we have to take into account differences in citation practices not only between humanities and sciences but also within narrower fields of humanities. In the current study we observe differences between publication behaviour of historians and archaeologists, examine some aspects of citation practices in those fields, and show their effect on visibility.     

The Popov criterion and the inverse Nyquist method†

Kosonbrock's inverse Nyquist array (I.N.A.) theory for linear multivariable control Bystema with constant feedback elements is extended, to include systems lip to m nonlinear feedback elements, where the system has m inputs and m outputs. This extension is achieved by considering the Popov criterion for the most general case and through two further theorems. It shows that, as in the ease of Rosenbrock's I.N.A. theory, when certain auxiliary conditions are met with the help of suitable controllers, the design of multivariable controllers containing many non-linear feedbacks, can be based on the m frequency response loci corresponding to the diagonal entries of the open-loop inverse transfer function matrix. This leads to a simple design technique identical to the I.N.A. design method, suitable for use with a computer-aided design facility which permits a designer to use his intuitive understanding of transfer functions based on classical theory. The I.N.A. theory has been extended by Rosenbrock to cover systems having non-linear, time-varying feedback elements very recently.     

Investigation of factors affecting the dispersibility of clays and estimation of dispersivity

Dispersive soils have caused failure of many slopes and earth fills due to external and internal erosion. This study aims to investigate various factors used for identification of dispersivity and to develop some new approaches for the prediction of dispersivity of clays. To achieve this purpose, physical and index properties, as well as degree of dispersivity of 29 clay samples taken from five different locations in and around the city of Ankara were determined. Various statistical prediction models were used for prediction of new dispersivity classes obtained by weighting ranking method. It was determined that dispersivity classes obtained from physical and chemical dispersivity tests performed on the same clay samples using distilled water were different from each other. In addition, crumb and pinhole tests were performed by using test waters with varying TDS values on five selected samples to find the impact of water chemistry on dispersivity. It is concluded from all dispersivity tests that total dissolved salts (TDS) values and sodium percentage (SP) remarkably affect the degree of dispersivity, and the use of these two parameters give more reliable results for the determination of dispersivity. By considering all these facts and to predict the most reliable dispersivity class, all dispersivity classes obtained from physical and chemical dispersivity tests were reevaluated by a weighted ranking system, and new dispersivity classes were assigned. In order to estimate these new dispersivity classes, various statistical models were established by using results of chemical analysis of pore water of clay samples. For this purpose, prediction models including soft computing methods such as decision tree and logistic regression are used and most reliable prediction models having the highest prediction performance are suggested.     

SOME OBSERVATIONS ON AIR MOVEMENTS IN CLEAN ROOMS WITH UNIDIRECTIONAL AIR FLOW

ABSTRACT

To avoid particle contamination in clean process production, unidirectional air flow with HEPA-filtered air is used, either in the entire room or partly in the critical process region (clean air zones), the purpose of this presentation is to describe a number of observations in unidirectional air flow and to discuss the interaction between air movements and the dispersion of airborne contaminants, it has been shown, by using smoke photography technique, that wake regions and vortex streets can easily be formed behind the working operator and objects. If a contaminant is emitted in the region of a vortex an accumulation can occur. It is important for the user to investigate that such vortices do not occur in the clean working zone.     

Environmental fatigue behavior of non‐crimp,E‐glass fiber reinforced polyester composites for marine applications

This study is aimed to find the fatigue behavior of Glass Reinforced Plastics, a material which is a widely preferred material for small marine crafts, as well as several other applications. The type of composite tested is hand‐laid E‐glass non‐crimp reinforcements with an polyester resin matrix. The specimens were produced in two standard thicknesses and with these material directions and were tested both under atmospheric and simulated seawater environments for fatigue. It was seen that the results of fatigue lifetime obtained by testing the material in seawater is much lower than the results obtained from testing similar specimens under atmospheric conditions. However, the stress curves indicate the same slope, suggesting that the fatigue failure mechanism of both testing conditions is the same and the fiber‐related factors dominate. It was found that the thickness and material direction did not have a significant effect on the fatigue behavior of the material.     

ARTIFICIAL INTELLIGENCE GOES MOBILE

New mobile computing technologies require new paradigms for infrastructure and interaction with mobile and networked devices. For building smart mobile companions for new intelligent services, a number of challenges have to be addressed. We argue that artificial intelligence is a key to a new generation of mobile systems. In this introduction to AI in mobile systems, we present some of the challenges and solutions in this exciting field of research.     

Diagonal stabilization of linear multivariable systems

A new procedure is presented for the synthesis of diagonal compensators for N × N linear multivariable systems that are free of fixed modes with respect to constant diagonal output feedbacks. The synthesis procedure employs simple polynomial algebra and it is in the form of an N-step algorithm. The geometric configurations 2N- and 2^N-cells in N-space are shown to be especially suitable for visualizing diagonal feedback and aiding the application of the synthesis algorithm.