Application of response surface methodology for weld strength prediction in laser welding of polypropylene/clay nanocomposite

Welding as a fabrication process can be used to join materials, including composite and nanocomposites and laser welding process due to its advantages has found wide applications in this field. Its process parameters can play a significant role in determining the weld strength of laser-welded joints in polypropylene/clay nanocomposites. In this study, the effect of laser welding parameters, such as laser power, welding speed and focal position along with the clay content in a polypropylene/clay nanocomposite on weld strength were determined using response surface methodology. This methodology was applied for developing a mathematical model which can predict the main effects of the above parameters and their impacts on tensile strength of butt-welded laser joints in 2-mm thick polypropylene/clay nanocomposite sheets. The analysis of variance was performed to check the adequacy of the developed model. A comparison was also made between the predicted and actual results. The results showed that weld strength decreased when clay content was increased from 0 to 6 %, but welding speed increased from 30 to 60 mm/s. The above parameters were also optimized to achieve a high strength welded joint.     

纳米微气泡存在下浮选机和浮选柱回收细粒磷酸盐矿物的比较

细粒浮选一直是许多矿物加工厂面临的主要问题之一.由于细颗粒的气泡粒子碰撞概率很低,因此降低了浮选效率.细粒的存在通常不利于浮选过程,影响了浮选精矿的选择性和质量,而且增加了试剂的消耗量.因此,在大多数加工厂中,会将部分颗粒输送到尾矿池中,以减少这些问题的影响,并提高浮选过程的选择性.由于d80小于30μm的颗粒的存在,...     

High-temperature performance of gilsonite-modified asphalt binder and asphalt concrete

This article investigates the effect of addition of gilsonite (natural bitumen) to asphalt binder on its rheological behavior at high temperatures through construction of complex modulus (G*) master curve using dynamic shear rheometer (DSR) test. This impact is further investigated by evaluation of performance of asphalt concrete modified with gilsonite at elevated temperatures using repeated dynamic creep test. The results showed that introduction of gilsonite to asphalt binder increases its stiffness and elasticity. Also, the results indicated that the modification of asphalt concrete with gilsonite improved rutting resistance significantly.     

An investigation on the performance of a FTS fixed-bed reactor using CFD methods

In the present work, a numerical model was developed and validated in order to simulate and improve the conversion of synthesis gas (CO + H₂) to higher hydrocarbons in a Fischer–Tropsch Synthesis (FTS) fixed-bed reactor. The reactor was a 3.1 cm diameter and 2.75 m length steel tube in which saturated water was employed to control the peak temperature within the catalyst bed. A 2-D CFD model with an optimized mesh of 22,016 square cells was developed to model hydrodynamics, chemical reaction, non-ideality of the mixture, heat and mass transfer in the reactor. Good agreement was achieved between pilot experimental data and the model. The result showed that adjusting the boiling water flow rate in the range of 25–250 g.min^{– 1} allows maintaining the FTS temperature at suitable values. An optimum value of 573 K was obtained for feed temperature.     

Structural Effects of HZSM-5 Zeolite on Methanol-to-Propylene Reaction

ZSM-5 zeolite was synthesized using n-butylamine as a template under hydrothermal conditions. The morphology of the prepared zeolites was changed with the initial gel composition. The influences of OH⁻/template and H₂O/template ratios on the morphology, mesoporosity, acid properties, and crystal size of the synthesized zeolites were evaluated, also the structural effects of the prepared zeolites on the catalytic performances of the methanol-to-propylene process. Increasing the external surface area and mesopore volume of the catalysts improved the propylene selectivity. A direct relationship between the deactivation of catalysts and their acidic properties was found. The results were derived from laboratory data and need to be re-examined on a larger scale to ensure their accuracy on an industrial scale.     

A Comparative Analysis of Data-Driven Models (SVR,ANFIS, and ANNs) for Daily Karst Spring Discharge Prediction

Water Resources Management - Spring discharge always illustrates the groundwater-flux and aquifer storage oscillations. Because of inherent heterogeneity in karst environments, it is essential to...