Using refined kano model and decision trees to discover learners’ needs for teaching videos

Multimedia Tools and Applications - With the advancement of technology and the spread of the COVID19 epidemic, learning can no longer only be done through face-to-face teaching. Numerous digital...     

Torque Transfer to a Conducting Particle Using the Lorentz Force

Semiconductors - In this work, we discuss for the first time the principle of rotation in the constant electric field of a conducting particle with participation of the Lorentz force, which ensures...     

Use of Nuclear Energy in Outer-Space Systems

Atomic Energy - The history and direction of further development of space nuclear energetics are examined. The functional diagram and principle of operation of a promising, powerful,...     

Modulation of electrical transport in calcium cobaltite ceramics and thick films through microstructure control and doping

Ca₃Co₄O₉ is a promising p-type thermoelectric oxide material having intrinsically low thermal conductivity. With low cost and opportunities for automatic large scale production, thick film technologies offer considerable potential for a new generation of micro-sized thermoelectric coolers or generators. Here, based on the chemical composition optimized by traditional solid state reaction for bulk samples, we present a viable approach to modulating the electrical transport properties of screen-printed calcium cobaltite thick films through control of the microstructural evolution by optimized heat-treatment. XRD and TEM analysis confirmed the formation of high-quality calcium cobaltite grains. By creating 2.0 at% cobalt deficiency in Ca_2.7Bi_0.3Co₄O_9+δ, the pressureless sintered ceramics reached the highest power factor of 98.0 μWm^?1 K^-2 at 823 K, through enhancement of electrical conductivity by reduction of poorly conducting secondary phases. Subsequently, textured thick films of Ca_2.7Bi_0.3Co_3.92O_9+δ were efficiently tailored by controlling the sintering temperature and holding time. Optimized Ca_2.7Bi_0.3Co_3.92O_9+δ thick films sintered at 1203 K for 8 h exhibited the maximum power factor of 55.5 μWm^?1 K^-2 at 673 K through microstructure control.     

The Central Lyapunov Limit Theorem and the Property of the Asymptotic Normality of the Sequence of Stable Polynomial Coefficients

Journal of Computer and Systems Sciences International - It is shown that the Lyapunov theorem on the distribution properties of the sum of random variables with different distribution densities...     

Technological Aspects of Synthesizing Ceramic Coatings by Flow-Through Micro-Arc Oxidation

Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized...     

Influence of Titanium Excess in a Ti–Si Reaction Mixture on the Synthesis of a Composite in a Combustion Wave

Theoretical Foundations of Chemical Engineering - On the basis of the classic concepts of the theory of solid-phase combustion, for the first time, a model with a detailed scheme of chemical...