Thermal buckling and postbuckling analysis of functionally graded annular plates with temperature-dependent material properties

As a first endeavor, the thermal buckling and postbuckling analysis of functionally graded (FG) annular plates with material properties graded in the radial direction is presented. The formulation is derived based on the first-order shear deformation theory (FSDT) and the geometrical nonlinearity is modeled using Green’s strain in conjunction with von Karman’s assumptions. The material properties are temperature-dependent and graded according to the power law distribution. It is assumed that the temperature varies along the radial direction. Using the virtual work principle, the pre-buckling and postbuckling equilibrium equations and the related boundary conditions are derived. Differential quadrature method (DQM) as an efficient numerical technique is adopted to solve the governing equations. The presented formulation and the method of solution are validated by performing convergence and comparison studies with available results in the literature. Finally, the effects of volume fraction index, geometrical parameters, mechanical/thermal properties of the constituent materials and boundary conditions on the thermal buckling and postbuckling behavior of the radially graded annular plate are evaluated and discussed.     

A Multimedia Information Repository for Cross Cultural Dance Studies

Multimedia technologies provide effective means for studying the evolution of dance across time and space. The study may be at the micro level which analyzes the development of an individual's performance and the movements of the dancer(s) in 3D space and over the length of the dance. However, at the macro level, diffusion of dance throughout the world over a span of time may be investigated in order to trace particular dance repertoires that may have traveled across various cultures and traditions. Although clearly different with respect to the expected objectives, both micro level analysis and macro level analysis require detailed comparison of patterns on the basis of certain characteristics that are deemed significant for a given dance. These characteristics are diverse in nature and may include such parameters as design formations, use of space (including level, direction, etc.), dynamics, paraphernalia (e.g., swords, sticks, etc.), sound, and color.We present the design of a multimedia information system with two complimentary aims. The first is to automate, to the greatest degree possible, the process of comparison and analysis of dance and human movement. Much of the information about dance exists in the form of video, images, audio and written commentaries, all collected into a digital library. As dance related materials are added, a wide variety of routines are needed to extract the necessary low level features from the multimedia objects. These low level features are then interpreted to human understandable features and patterns, which will be used for analysis by specialists. The second aim is to bring artists and technologists closer in a meaningful way.     

The effects of water absorption and surface treatment on mechanical properties of epoxy nanocomposite using response surface methodology

In this study, the dynamic-mechanical properties of fumed silica and silane-treated reinforced epoxy nano-composites were examined; silane-treated specimens demonstrated greater glass transition temperature, modulus, and less moisture absorption. An epoxy composite has been studied under hydrothermal ageing in order to investigate the effect of treatment on dynamical mechanical thermal analysis. The nanocomposites were kept in seawater up to 600 h. The process was then modeled using response surface methodology based on central composite design (CCD). Three models were developed to predict the influence of wet aging parameters on the Tg, modulus, and damping. Accuracy of predicted results was analyzed by the analysis of variance method. The optimum values predicted by the RSM and CCD were 1 % wt treated fumed silica followed by aging at 60 °C. Multiple correlation coefficients (R ²) of 0.96 were obtained from the regression models for Tg, confirming the good accuracy of developed models.     

Digital Textbooks

The traditional publishing industry is seeing the first signs of its own doom while desperately hanging on to the last few dollars of profit from selling pulped forest trees. The demise of paper-based publishing is as certain and as inevitable as the end of the use of stone hieroglyphics. It's likely that Generation X will be the last to support the traditional print-publishing industry. The rationale for this prediction is simple: there is absolutely no reason for high school students to carry around pounds of books in their backpack when almost everything else is now paperless. In the following paragraphs, I will explain why the extinction of paper-based textbook publishing is inevitable and why the strategies of the publishing industry to maintain its grip should be viewed as last-gasp efforts.     

A logical framework for visual information modeling and management

A unified semantic visual data-modeling framework is presented in the paper. In the proposed model, an extended conceptual graph is proposed as an annotation mechanism of a user's perceptual understanding of video objects, activities, and events. A precise definition of the term domain knowledge in visual information processing is presented. A conceptual structure, associated terms, visual feature extraction methods, and a set of constrains in feature extraction are considered as domain information. The proposed visual data model has six different abstraction layers. A higher level is more abstracted and more semantically summarized. A polygon-based bounding volume is used in video object approximation in space and time. We use a bounding volume in motion trajectory representation, rather than motion vectors. This model allows simultaneous access of both temporal and spatial information. The proposed model may be used as a referencing framework for various visual information management systems' developments.     

Improvement of ECAP process by imposing ultrasonic vibrations

The International Journal of Advanced Manufacturing Technology - In a few last decades, equal-channel angular pressing (ECAP) has been one of the most prominent procedures for fabrication of...     

Determination of Pb(II) Ions Using Novel Ion-Imprinted Polymer Magnetic Nanoparticles: Investigation of the Relation Between Pb(II) Ions in Cow’s Milk and Their Nutrition

The application of novel Pb(II) ion-imprinted polymer coated on magnetic mesoporous silica was investigated in preconcentration and determination of low level of Pb(II) ions. The job proposed a new method for preconcentration and determination of Pb(II) ions. This novel sorbent was characterized by scanning electron microscopy, thermal gravimetric/differential thermal analysis, elemental analysis, and low-angle X-ray powder diffraction. Effects of various factors such as the effects of the pH of sample solution, eluent (include type, concentration and volume), adsorption and desorption time which are effective in method efficiency, were appraised through this study. In order to investigate the selectivity of this sorbent toward Pb(II) ion, the effects of variety of foreign ions interfering on preconcentration and recovery of Pb(II) ions were also investigated. The limit of detection (LOD) was found to be 0.7 μg L^?1 and the recovery and relative standard deviation of the method were 96.6–102.4 % and 1.3–3.3 %, respectively. Validation of the outlined method was performed by analyzing several standard reference materials with certified Pb(II) concentrations. Finally, this sorbent was applied for separation and determination of Pb(II) ion in grass and cow’s milk, which showed their lead concentration to be below the detection limit of flame atomic adsorption spectroscopy.     

Cadmium Ions Determination in Sea Food Samples Using Dipyridyl-Functionalized Graphene Nano-sheet

In this work, graphene nano-sheets was modified by dipyridyl amine group and used as a novel sorbent for selective separation and preconcentration of cadmium ions. The sorbent was characterized by infrared spectroscopy, transmission electron microscopy, thermal analysis, and elemental analysis. The application of this sorbent was investigated in determination of cadmium ions in sea food samples by flame atomic absorption spectrometry. The effective parameters on adsorption and desorption of cadmium were optimized. The limit of detection, the relative standard deviation and the recovery of the established method were found to be 0.19 ng mL^?1, 1.6 %, and 99.1 %, respectively. The method was validated using various standard reference materials and was applied for cadmium determination in sea food sample.     

Determination of Sulfonamides in Chicken Meat by Magnetic Molecularly Imprinted Polymer Coupled to HPLC-UV

In this work, Fe₃O₄ magnetic nanoparticles were synthesized and modified by a molecularly imprinted polymer for easy and selective extraction and determination of sulfonamides in chicken meat samples. Imprinted polymer magnetic nanoparticles were characterized by Fourier transform infrared spectroscopy, X-ray diffraction pattern, thermal analysis, and scanning electron microscope micrograph. The template was removed by methanol elution. The effective parameters on extraction and determination of sulfonamides on the sorbent such as eluent type, extraction solvent, and adsorption and desorption times were optimized. Sulfonamide separation and determination were performed by high-performance liquid chromatography–UV. The linear ranges for sulfonamides were 0.5–150 μg/L and the limits of detection were 0.1–0.5 μg/L. Relative standard deviations were within 4.3–5.4 %. The method showed good selectivity for extraction of sulfonamides in real samples.     

Performance analysis of time-hopping spread-spectrum multiple-access systems: uncoded and coded schemes

An ultra-wide bandwidth time-hopping spread-spectrum code division multiple-access system employing a binary PPM signaling has been introduced by Scholtz (1993), and its performance was obtained based on a Gaussian distribution assumption for the multiple-access interference. In this paper, we begin first by proposing to use a practical low-rate error correcting code in the system without any further required bandwidth expansion. We then present a more precise performance analysis of the system for both coded and uncoded schemes. Our analysis shows that the Gaussian assumption is not accurate for predicting bit error rates at high data transmission rates for the uncoded scheme. Furthermore, it indicates that the proposed coded scheme outperforms the uncoded scheme significantly, or more importantly, at a given bit error rate, the coding scheme increases the number of users by a factor which is logarithmic in the number of pulses used in time-hopping spread-spectrum systems.