Microstructural Characterizations and Strength Development of Self-Compacting Concrete Using Rice Husk Ash

The conversion of waste and by-products into green building materials is gaining attention for a sustainable economy. Particularly, rice husk ash (RHA) is used as a precursor in self-compacting concrete due to its high pozzolanic activity. It also minimizes the use of conventional OPC as a primary binder during construction by exploiting its chemical features and characteristics as an alternative binding agent. Developing and mass-producing RHA as a cementitious material would lessen the carbon footprint that harms the environment. This study presents the compressive strength and microstructural characterizations of rice husk ash-based self-compacting concrete (RHA-SCC). The scanning electron microscope was utilized to determine the morphological images of RHA-SCC. The compressive strengths of 7, 28, and 90-day curing periods were also checked to relate how strength is developed from various sets of mixture proportions

Morphology, Conductivity, and Mechanical Properties of Electropolymerized Polypyrrole/Silver-Coated Granular Microsphere Composite Films

We report a facile synthesis of polypyrrole/silver-coated granular microsphere composite films through electropolymerization process in the presence of low- and high-density conductive granular microspheres. The resulting morphologies of composite films were implicitly influenced by the density of microspheres as revealed by scanning electron microscopy (SEM). Energy-dispersive X-ray (EDX) analysis confirmed the existence of elemental composition of the polypyrrole and conductive microspheres, while Fourier transform infrared (FTIR) spectroscopy verified the presence of molecular bonding associated with the dopant anion in all the synthesized films. Resistivity measurements demonstrated enhanced nonlinear conductivity and a strong dependence of current density in composite films with increasing application of electric field. Improvement in nonlinear conductivities is linked to the formation of more effective conductive pathways that boosted intermolecular and inter-particle charge carrier migration. Tensile tests reveal that the conductive granular microspheres have the general tendency to decrease internal forces in composite films

Dynamics of a Rotating Sphere on Free Surface of Vibrated Granular Materials

We investigate the rotational dynamics of a low-density sphere on the free surface of a vertically vibrated granular material (VGM). The dynamical behavior of the sphere is influenced by the external energy input from an electromagnetic shaker which is proportional to ε, where ε is equal to the ratio between the square of the dimensionless acceleration Γ and the square of the vibration frequency f of the container. Empirical results reveal that as the VGM transits from local-to-global convection, an increase in ε generally corresponds to an increase in the magnitudes of the rotational ω RS and translational v CM velocities of the sphere, an increase in the observed tilting angle θ bed of the VGM bed, and a decrease in the time t wall it takes the sphere to roll down the tilted VGM bed and hit the container wall. During unstable convection, an increase in ε results in a sharp decrease in the sphere\u27s peak and mean ω RS, and a slight increase in t wall. For the range of ε values covered in this study, the sphere may execute persistent rotation, wobbling or jamming, depending on the vibration parameters and the resulting convective flow in the system

Time evolution of neighbor-pair mutual information in collectively moving active granular particles

In recent decades, significant progress has been made in the field of active-matter research. Studies on biological active systems, in particular, have begun to adapt information-theoretic approaches in studying collective behavior in various systems. In this present work, we employ a novel information-theoretic framework based on connected mutual information (CMI) to quantify the similarities in the speed and polarization fluctuations among individuals in a system of 10–100 bio-inspired, vibrated active granular particles. By tracking the evolution of the speed and polarization CMI using 20-s time windows, we find that CMI estimates rise and fall over a 3-min observation period depending on the number of particles and the system\u27s overall mobility. Results of nonlinear analyses also reveal that the speed and polarization fluctuations are independent of each other, and that the sharing of speed and polarization information among active particles is maximized when the system is continuously circulating around the container, and minimized when the system is either jammed or is executing frequent directional switches from clockwise to counter-clockwise circulation and vice versa. The information-theoretic methodologies presented in this work can have potential applications in the study of different biological and artificial active systems

Pre‐conceptions of Newton’s Laws of Motion of Students in Introductory Physics

The Force and Motion Conceptual Evaluation (FMCE) developed by R.K. Thornton and D. R. Sokoloff was utilized to evaluate the conceptual understanding of Newton’s Laws of Motion. The test was administered to 100 freshman university students enrolled in introductory physics courses. The aim is to find out the conceptual understanding of the students prior to university level instruction. Results show that the Aristotelian notion prevails despite having taken physics in their senior year in high school. This study emphasizes the importance of training high school physics teachers and the significance of a change in the teaching techniques for university level introductory physics

Wavelength division multiplexing

Abstract not available

Active learning in optics and photonics: experiences in Africa

Widespread physics education research has shown that most introductory physics students have difficulty learning essential optics concepts - even in the best of traditional courses, and that well-designed active learning approaches can remedy this problem. This mini-workshop and the associated poster session will provide direct experience with methods for promoting students' active involvement in the learning process in lecture and laboratory. Participants will have hands-on experience with activities from RealTime Physics labs and Interactive Lecture Demonstrations - a learning strategy for large (and small) lectures, including specially designed Optics Magic Tricks. The poster will provide more details on these highly effective curricula