System Extremity Research Articles

A simulative approach to obtain higher temperatures during spark plasma sintering of ZrB2 ceramics by geometry optimization

This study provides a detailed analysis of the Spark Plasma Sintering (SPS) process for Zirconium Diboride (ZrB2) ceramics, utilizing the finite element method in COMSOL Multiphysics. The focus is on understanding the temperature distribution during the SPS of a ZrB2 sample in a graphite die. Heat diffusion equations, augmented with Joule heating considerations, are utilized to simulate temperature variations within the system over time. Critical boundary conditions at the system's extremities are modeled as convection cooling. The Analysis of Variance (ANOVA) reveals that the diameter of the sample is the most significant factor influencing the peak temperature at the center of the ZrB2 sample. It is found that the sample diameter's variance accounts for a predominant impact on temperature, markedly more than other factors such as the die's outer diameter and sample thickness. Notably, the standard deviation of the temperature in the axial direction across all samples is less than 4 °C, a value that is statistically minor in comparison to the sintering temperatures, which are around 2000 °C. These findings are instrumental in providing an in-depth understanding of the SPS process, which is essential for the optimization of sintering parameters for ZrB2 ceramics.

A mobile application to calculate optimum drip irrigation laterals

The parameters to be taken into account when installing a drip irrigation system include the diameters of piping to be used in the irrigation installation. Certain applications developed for PC permit an approximate calculation of these diameters outside the installation environment, which makes on-site optimization of the system difficult. This paper presents a software application developed for Android mobile devices by which the user can immediately evaluate the responsiveness of all of the available optimum commercial diameters to operational changes, such as changing water demands (e.g., cultivation, water needs, and spacing), types of emitters used in the installation, or lateral feeding (from an extreme or from an intermediate point). The input data mainly required by the application are: emitter flow rates, the number of emitters, the space between emitters, the average pressure in the lateral, and the pressure tolerance. As a result, the application indicates if each irrigation lateral is valid or not for the situation provided by the user, and displays some graphics of the pressures in the lateral that indicate the pressures at the system's extremities, which permits identification of the critical points of the irrigation lateral.

Seasonal variations of trihalomethanes (THMs) in water distribution networks of Istanbul City

Seasonal variations of trihalomethane (THM) concentrations were investigated within distribution systems of the Buyukcekmece water treatment plant in Istanbul City (Turkey). The investigation was based on an intensive 30-week sampling program, undertaken during the spring, summer and fall of the year 2003. THMs and other water quality and operational parameters were monitored at points along the distribution system between the treatment plant and the system's extremity. The results showed that THM concentrations vary significantly between finished waters and water at the distribution network. When water temperature exceeds 24°C in summer, the THM levels are 1.2–1.8 times higher than finished water, while when water temperature is below 15°C in the spring and fall, the measured THM concentrations at the system's extremity were very rarely higher than 100 μg/L. Finally, THM levels were measured at sampling points representing progressively greater travel times from the plant to the extremity of the distribution system. Multiple regression analysis was also conducted in order to estimate THMs from total organic carbon, temperature, and chlorine dose parameters. The regression model resulted in a R 2 value of 0.827.