Crystallization, microstructure and expansivity of spodumeneorthoclase glasses

The crystallization behaviour was investigated for some glasses, within the system spodumene-orthoclase, during different heat treatments by DTA, XRD and SEM. Kaolin and quartz sand were used as starting materials for the glass preparation and melting. The base glasses were stable through the heat treatments and did not show any crystallization propensity, whereas TiO2 additions catalyze the crystallization tendency in the glasses. The crystallization process involved the formation of β-spodumene and leceite in addition to the metastable high quartz, which disappeared at higher temperatures (>900 °C). Translucent glass-ceramies, containing uniform and nonuniform microstructures, were obtained in the ease of domination of high quartz and β-spodumene, respectively. Little difference in the coefficient of thermal expansion (CTE) was noted in the base glasses (64 to 66 ∙ 10^-7 at 20 to 500 °C) and the TiOs doped glasses (60 to 69 ∙ 10^-7 K^-1 at 20 to 500 °C). Change in CTE in the TiOs doped glass ceramie samples from 37 to 69 ∙ 10^-7 at 20 to 300 °C depends mainly on the content of crystallized β-spodumene in addition to the residual glass. However, an increase in β-spodumene content in the crystallized glass-ceramies lowers the value of CTE and vice versa

Passive Components for Ultra-Wide Band (UWB) Applications

UWB technology brings the convenience and mobility of wireless communications to very high-speed interconnects in the home and office due to the precision capabilities combined with the low power. This makes it ideal for certain radio frequency sensitive environments such as hospitals and healthcare as well as radars. UWB intrusion-detection radar is used for detecting through the wall and also used for security with fuse avoidance radar, precision locating and tracking (using distance measurements between radios), and precision time-of-arrival-based localization approaches. The FCC issued a ruling in 2002 that allowed intentional UWB emissions in the frequency range between 3.1 and 10.6 GHz, subject to certain restrictions for the emission power spectrum. Other definitions for ultra-wideband range of frequency are also used such as any device that has 500 MHz bandwidth or fractional bandwidth greater than 25% is considered an UWB enable high data rate to be transferred with a very low power that does not exceed −41.3 dBm

Non-Invasive Electromagnetic Biological Microwave Testing

Blood glucose monitoring is a primary tool for the care of diabetic patients. At present, there is no noninvasive monitoring technique of blood glucose concentration that is widely accepted in the medical industry. New noninvasive measurement techniques are being investigated. This work focuses on the possibility of a monitor that noninvasively measures blood glucose levels using electromagnetic waves. The technique is based on relating a monitoring antenna’s resonant frequency to the permittivity, and conductivity of skin, which in turn, is related to the glucose levels. This becomes a hot researched field in recent years. Different types of antennas (wideband and narrowband) have been designed, constructed, and tested in free space. An analytical model for the antenna has been developed, which has been validated with simulations. Microstrip antenna is one of the most common planar antenna structures used. Extensive research development aimed at exploiting its advantages such as lightweight, low cost, conformal configurations, and compatibility with integrated circuits have been carried out. Rectangular and circular patches are the basic shapes that are the most commonly used in microstrip antennas. Ideally, the dielectric constant εr, however, and other performance requirements may dictate the use of substrate whose dielectric constant can be greater. As in our prototype blood sensor, the miniaturized size is one of the main challenges

Efecto de antioxidantes naturales en la estabilidad de carne de ostra durante su almacenamiento

Meat from the ostrich is becoming increasingly popular throughout the world. The aim of the current study was to evaluate the effects of different antioxidants such as ascorbic acid (AA), α-tocopherol (Toc) and rosemary herb (Ros) on the stability of ostrich meat during storage. The chemical composition of ostrich meat showed low fat content (1.5 %) combined with high protein content (22.4 %). The combination of AA + Ros, Toc + Ros and AA + Toc was more effective in reducing the thiobarbituric acid (TBA) and peroxide values. The antioxidant showed insignificant effects on acidity as oleic acid. The addition of the efficient role of AA, Toc and Ros showed an improvement in the color stability of ostrich steaks and the combined treatment was more effective in color stability. In conclusion, the addition of AA, Toc and Ros had a positive effect on aroma quality, rancidity and discoloration of refrigerated ostrich meat.La carne de ostra es cada vez más popular en todo el mundo. El objetivo de este estudio fue evaluar el efecto de diferentes antioxidantes tales como el ácido ascóbico (AA), el α-tocoferol (Toc) y hierbas de romero (ROS) en la estabilidad de la carne de ostra durante el almacenamiento. La composición química de la carne de ostra mostro un contenido bajo en grasa (1.5%) en combinación con un alto contenido de proteínas (22.4%). Las combinaciones de AA + Ros, Toc + Ros y AA + Toc fueron las más efectiva en la reducción de los valores de ácido tiobarbitúrico (TBA) y de peróxidos. Los antioxidantes muestran un insignificante efecto en la acidez como ácido oleico. La adicción de AA, Toc y Ros mostro una mejora de la estabilidad del color de los filetes de ostra, es más, el tratamiento combinado fue más efectivo en la estabilidad del color. En conclusión, la adicción de AA, Toc y Ros tuvo un efecto positivo en el aroma, rancidez y decoloración de la carne refrigerada de ostra

Determinants of technical efficiency of freshwater prawn farming in southwestern Bangladesh

This paper estimates a translog stochastic production function to examine the determinants of technical efficiency of freshwater prawn farming in Bangladesh. Primary data has been collected using random sampling from 90 farmers of three villages in southwestern Bangladesh. Prawn farming displayed much variability in technical efficiency ranging from 9.50 to 99.94% with mean technical efficiency of 65%, which suggested a substantial 35% of potential output can be recovered by removing inefficiency. For a land scarce country like Bangladesh this gain could help increase income and ensure better livelihood for the farmers. Based on the translog production function specification, farmers could be made scale efficient by providing more input to produce more output. The results suggest that farmers’ education and non-farm income significantly improve efficiency whilst farmers’ training, farm distance from the water canal and involvement in fish farm associations reduces efficiency. Hence, the study proposes strategies such as less involvement in farming-related associations and raising the effective training facilities of the farmers as beneficial adjustments for reducing inefficiency. Moreover, the key policy implication of the analysis is that investment in primary education would greatly improve technical efficiency

An Extension of Estimation of Domain of Attraction for Fractional Order Linear System Subject to Saturation Control

This paper employs the Lyapunov direct method for the stability analysis of fractional order linear systems subject to input saturation. A new stability condition based on saturation function is adopted for estimating the domain of attraction via ellipsoid approach. To further improve this estimation, the auxiliary feedback is also supported by the concept of stability region. The advantages of the proposed method are twofold: (1) it is straightforward to handle the problem both in analysis and design because of using Lyapunov method, (2) the estimation leads to less conservative results. A numerical example illustrates the feasibility of the proposed method

Comparison between the calculated and measured dose distributions for four beams of 6 MeV linac in a human-equivalent phantom

Radiation dose distributions in various parts of the body are of importance in radiotherapy. Also, the percent depth dose at different body depths is an important parameter in radiation therapy applications. Monte Carlo simulation techniques are the most accurate methods for such purposes. Monte Carlo computer calculations of photon spectra and the dose ratios at surfaces and in some internal organs of a human equivalent phantom were performed. In the present paper, dose distributions in different organs during bladder radiotherapy by 6 MeV X-rays were measured using thermoluminescence dosimetry placed at different points in the human-phantom. The phantom was irradiated in exactly the same manner as in actual bladder radiotherapy. Four treatment fields were considered to maximize the dose at the center of the target and minimize it at non-target healthy organs. All experimental setup information was fed to the MCNP-4b code to calculate dose distributions at selected points inside the proposed phantom. Percent depth dose distribution was performed. Also, the absorbed dose as ratios relative to the original beam in the surrounding organs was calculated by MCNP-4b and measured by thermoluminescence dosimetry. Both measured and calculated data were compared. Results indicate good agreement between calculated and measured data inside the phantom. Comparison between MCNP-4b calculations and measurements of depth dose distribution indicated good agreement between both