A spin-1/2 gapped compound CdCu2(SeO3)2Cl2 with ladder structure

The exploration of two-leg spin-ladder materials is a great challenge to chemical community since it is one of the most ideal models for the study of low-dimensional magnetism and high-Tc...

A study of rock ladder structure used in buffer storage of iron ore pellets: DEM simulation and analytical model

Purpose This paper aims to analyze the abrasive damage of iron ore pellets (IOP) during charge inside day-bins in iron making plants. The rock-ladder structure of day-bin is the spotlight of this study. A numerical-analytical method is used to investigate the main geometrical features of the mentioned structure. Practical results of this study are expected to result in optimization of rock-ladder structure to reduce fine generation and lump formation during pellets downfall on the floors of rock-ladder. Design/methodology/approach One effective stage of pellets downfall on the floor of rock-ladder was simulated using discrete element method. A special post-process code is used to calculate parameters of pellets collisions for an analytical model which estimates fine generation during collisions. The main damaging mechanism during pellets storage inside day-bin is determined based on the comparison of the numerical-analytical results and industrial reports. Different rock-ladder designs are simulated to find optimal geometry of the rock-ladder structure. Findings According to the results, 85.4% of fines generation takes place during downfall of IOPs on the floors of rock ladder, and the rest of the fine debris is expected to be generated due to flow down under compressive load and vibratory discharge. The present study suggests an increase in the rock ladder floors distance from 1.63 to 2 m, but this suggestion should be confirmed by another study focusing on the breakage damage of IOPs. The idea of chamfering the floors corners not only removes lump-formation zones but also results in an approximately 5.7% reduction in the fines generation rate. Originality/value According to the results, introduced modification ideas for rock-ladder structure can result in lower fine generation, lower lump removal cost and lower manufacturing cost of rock-ladder structure.

SYNTHESIS OF QUASI BAND LADDER TRANSFORMING HIGH ORDER FILTERS

The purpose of the work, the results of which are presented in the article, was to develop a computerized mathematical model of the ladder filter to study the features of the synthesis of matching chains of any order on its basis. To achieve this goal, all the synthesis tasks were solved, including the choice of the prototype, frequency transposition, calculation of the poles of the transfer function of the prototype, calculation of the poles of the transfer function of the filter, calculation of the reflection coefficient of the filter, the calculation of the input resistance of the filter, the implementation of the ladder chain by the Cauer method and denormalization of the values of the elements of the ladder chain. Modeling of characteristics of ladder filters of any high order with frequency characteristic of Chebyshev on the computer with 32-bit operating system is carried out. It is shown that the use of standard mathematics leads to a significant increase in the error of matching of loads at increasing the order of the chain. To increase the accuracy of calculations it is proposed to use software that allows implementing mathematical operations on variables with any length of the mantissa. There are computer libraries where numbers are presented in the form of string type variables and arithmetic operations are carried out on them according to school rules “ in a column ” . Once the calculations are completed, the strings are converted back to normal numbers. The article considers the application of the variant of BigNumber library for high level JavaScript language. To estimate the accuracy of the calculation it is proposed to apply the property of antimetric ladder structure. From the presented results of the calculation it follows that in order to obtain not less than 15 reliable digits after the decimal point for the parameters of the n-th order filter it is necessary to increase the length of the variable mantissa to the value 2n.