Effect of some nucleating agents on thermal expansion behaviour of Li2O-BaO-Al2O3-SiO2 glasses and glass-ceramics

The thermal expansion behaviour of some glasses and glass-ceramics within the system spodumence (LiAlSi2O6)-celsian (BaAl2Si2O8) containing LiF, TiO2 and Cr2O3 as nucleation catalysts was described. LiF and TiO2 were found to increase the thermal expansion of the glasses investigated, whereas Cr2O3 slightly lowered the expansion coefficient. The dilatometric transition and softening points of the glasses showed the reverse behaviour. The thermal expansion of the glass-ceramics was a function of type and amount of nucleating agent and heat treatment which greatly affected the mineralogical constitution of the materials

Predicting and Controlling Fertility Using Family Planning Methods

Without a real reduction in population fertility rates, developing societies will push for more spending on their infrastructure and more demand for basic services for new-born, and more dependency and crowding, and the attendant ills and various social, economic and cultural problems, which will push these countries towards Directing a large part (if not most) of development revenues to meet the growing population. In general, the importance of this study lies in how to predict fertility rates using the rates of family planning methods (practice rates, years of protection) and to identify the method of neural networks and its accuracy in dealing with fertility data in particular. The study concluded that the prevalence of family planning methods (PR) and protection rate (CYP) are used to estimate and predict the total fertility rate (TFR) very efficiently, and artificial neu6ral networks have reached a high rate and high accuracy in estimating and predicting the total fertility rate (TFR) is highly and reliable (99.6%)

Development of High Thermal Stability Geopolymer Composites Enhanced by Nano Metakaolin

This paper deals with study of thermal stability of geopolymer composites enhanced by nano metakaolin materials (NMK) and exposed to high firing temperature up to 1000 °C. The main geopolymer made up of water cooled slag having various kaolin ratios.  The activators used are Na2SiO3 and NaOH in the ratio of 3:3. The thermo-physical, micro-structural and mechanical properties of the geopolymers before and after the exposure to elevated temperatures of 300, 500, 600 800 and 1000 °C have been investigated. The fire shrinkage of the geopolymer specimens increased by increasing temperature up to 1000 oC. Also, the fire shrinkage increased slowly up to 500 °C. The mechanical strength of geopolymer specimens increased with temperature up to 500 oC. The good thermo-physical and mechanical properties for these geopolymer composites increase the possibility of vast application of these eco-friendly materials in construction sectors

Alkali Activated Eco-friendly Metakaolin/Slag Geopolymer Building Bricks

Alkali activation of alumino-silicate materials is a complex chemical process evolving dissolution of raw materials, transportation or orientation and polycondensation of the reaction products. This study explores the physico-mechanical characteristics of geopolymer bricks using eco-friendly slag/metakaolin binder. Alkaline activation of slag – metakaolin binder of geopolymer brick results in formation of C-A-S-H as well as N-A-S-H gel, which adopts different structures depending on the nature of the alkaline activator. Activators used are 10% NaOH solution in addition to 5% liquid sodium silicate both used from the total binder weight), Geopolymer bricks prepared by partial binder substitution of metakaolin (fired kaolin) by water cooled slag in the ratio from 0 up to 100 %, while the used fine sand(passing 1 mm) in the ratio of 15% from the total weight. The properties of the produced geopolymer bricks have been studied through measurement of compressive strength, water absorption, FTIR, XRD and SEM imaging. Results demonstrate the possibility of substitution of metakaolin by water cooled amorphous slag materials in producing geopolymer bricks with superior properties where an increase in mechanical strength with water cooled slag increase up to 40 %  was noticed giving compressive strength values exceed 70 MPa which can be used for production of  heavy duty  bricks which can be applied in a severe weathering condition as well as special purposes building applications, however further increase results in lowering strength values as a  but still exceed 30 MPa after 28 days of hydration. Keywords: slag, metakaolin, bricks, eco-friendly, sustainability

On the stationary vibrations of a rectangular plate subjected to stress prescribed partially at the circumference

The stationary periodical problem of a vibrating rectangular plate, stressed at a segment while fixed elsewhere at one of its edges, is considered. Using the finite Fourier transformation, the problem is converted to a singular integral equation that in turn can be reduced to an infinite system of algebraic equations. The truncation of the algebraic system is justified

The Performance of Cold-Formed Steel Members with Stiffened Perforations

CFS sections are usually supplied with openings to adapt construction services. Nevertheless, the area lowering in the web influences their strengths. If stiffeners are provided near the web openings, the reduction in flexural capacity could be recovered. Therefore, this paper introduces a study on the CFS section with stiffened perforations. A finite element (FE) analysis was accomplished. The numerical model was verified versus experimental and numerical tests from prior research and then utilized in performing parametric studies. The influence of circular openings with various sizes and various stiffener lengths on the flexural capacity was examined in the nonlinear analysis. Depending on the findings of the study, it has been determined that the introduction of stiffened openings into the CFS members will result in the restoration of the original flexural capacity

Parametrically controlling solitary wave dynamics in modified Kortweg-de Vries equation

We demonstrate the control of solitary wave dynamics of modified Kortweg-de Vries (MKdV) equation through the temporal variations of the distributed coefficients. This is explicated through exact cnoidal wave and localized soliton solutions of the MKdV equation with variable coefficients. The solitons can be accelerated and their propagation can be manipulated by suitable variations of the above parameters. In sharp contrast with nonlinear Schr\"{o}dinger equation, the soliton amplitude and widths are time independent.Comment: 4 pages, 5 eps figure

Activation of Air and Utilities in the National Ignition Facility

Detailed 3-D modeling of the NIF facility is developed to accurately simulate the radiation environment within the NIF. Neutrons streaming outside the NIF Target Chamber will activate the air present inside the Target Bay and the Ar gas inside the laser tubes. Smaller levels of activity are also generated in the Switchyard air and in the Ar portion of the SY laser beam path. The impact of neutron activation of utilities located inside the Target Bay is analyzed for variety of shot types. The impact of activating TB utilities on dose received by maintenance personnel post-shot is analyzed. The current NIF facility model includes all important features of the Target Chamber, shielding system, and building configuration. Flow of activated air from the Target Bay is controlled by the HVAC system. The amount of activated Target Bay air released through the stack is very small and does not pose significant hazard to personnel or the environment. Activation of Switchyard air is negligible. Activation of Target Bay utilities result in a manageable dose rate environment post high yield (20 MJ) shots. The levels of activation generated in air and utilities during D-D and THD shots are small and do not impact work planning post shots