Abstract

This case study focuses on the electrical resistivity of soil from two barangays of San Jose del Monte, Bulacan (SJDMB) using the Wenner four-pin method. The Wenner Method makes use of four electrodes or pins buried on the soil that are equidistant to each other. These electrodes are connected to the measuring device where the outer pins indicate the induced current and the inner two represents the potential difference across the soil. From the data gathered, the value of soil resistivity was then determined and analyzed using the formula gathered from the literature. Comparison to the soil resistivity of two areas was made. Results show that the soil sample from barangay Sto. Cristo has a low resistivity than the sample from Towerville, Minuyan Proper.

Index Terms

soil properties, soil resistivity, conductivity, resistivity

Abstract

A fuzzy logic-based controller has been designed to assist in manual control of a UAV. Manual flight control of UAV via joystick basically requires some level of mastery, i.e. hours of UAV flight training. Mastery means that an operator is able to control the attitude and heading of the UAV indirectly by maneuvering through the control surfaces, as well as maintain control and smooth cruising given the fact that aerial vehicles are always subjected to noise and disturbances. Hence, there is a need for an assisting control algorithm that will receive commands from the operator (via joystick) and execute the attitude and heading of the UAV as desired. Motivated by the difficulty and drawback of full manual control of a UAV in the present, a fuzzy logic-based system is preferred to design an assisting algorithm that will implement a fly-by-wire control.

Index Terms

fuzzy logic, fly-by-wire, fixed-wing, UAV control

Abstract

When a single streak of light passes through an aperture or a lens, a diffraction pattern containing a central disk or Airy disk having a finite diameter and encircled by a fading series of concentric rings called Airy pattern is produced as its image. In this experiment, we measure the diameter of a few guitar strings by utilizing the diffraction pattern produced. Here, a small aperture made by impaling a guitar string on a paper was exposed to a beam of light thus, creating a diffraction pattern. We found that the smallest aperture created that has a diameter of 3143 m, has an error of 3% from the indicated diameter. This implies that our method is capable of measuring thin strings or small apertures accurately. This technique, nonetheless, has a specific restriction of about 600 m in width having an error of 5%.

Index Terms

Circular aperture, Fraunhofer diffraction, Airy disk, Bessel function, guitar string measurement

Abstract

The effects of formulation factors on the swelling property of a bio-based coating in different solvents were investigated. Film coating from Talisay (Terminalia catappa) seed oil extract was prepared via a rapid and simple method in crosslinking triglyceride 2-mercaptoethanol and diphenylmethane diisocyante (MDI) via photopolymerization. Swelling measurements of the film coating was performed using water and dichloromethane as solvents. Results show that increasing the Oil/Thiol and Oil/MDI ratios increase the swelling of the film coating in dichloromethane.

Index Terms

Bio-based, coating, photopolymerization, swelling

Abstract

Musical instruments specifically, a guitar and ukulele have their own unique and distinct sound qualities despite being similar in so many ways. This is true as to how the sound of both instruments, even while producing the same note, could be clearly distinguished from one another simply by listening. This difference in sound quality was investigated by looking into the harmonics and obtaining the power spectrum of both instruments producing an E4 note. The fundamental frequency of an E4 note was obtained from the graphs and has the same value of 326.34 ± 4.41 Hz which has a deviation of 1% from the theoretical value for both instruments. With the guitar showing the most number of harmonics, up to the 7th than the ukulele, up to the 4th only. The spectral envelopes and radar charts were also plotted. Results showed that the difference in the amplitude values for every harmonic in the power spectrum, the difference in the form of the spectral envelope and its radar chart are what explains why the two instruments sound unique from each other.

Index Terms

harmonics, power spectrum, sound, spectral envelope

Abstract

This study investigated the effects of varying the channel geometry of a microfluidic chamber to the flow of particles in a fluid. The channel geometry used consisted of a wide straight channel connected to a narrow straight channel by a trapezoidal-shaped junction. Computer simulations were done using a channel design consisting of a trapezoidal-shaped channel connected to a straight channel. Using a CFD program, the effect of the trapezoidal-shaped channel serving as inlet or outlet to the fluid motion was investigated. The simulations were confined to varying which of the two channels served as the inlet. Therefore, only two sets of simulations were done. The first set of simulations was that of the trapezoidal-shaped channel serving as the inlet connected to the straight channel which served as the outlet. The second set of simulations was done by making the straight channel serve as the inlet and the trapezoidal-shaped channel was connected to it, therefore serving as the outlet. A linear trend was observed on the values of the maximum velocity and maximum shear stress with respect to the change in the width of the straight channel and the half-angle of the trapezoidal channel. As both the width and the half-angles were increased, the maximum values of both the velocity and shear stress also increased. Experiments were done to demonstrate the results obtained using the simulations. Another microfluidic chamber design was used for the fabricated chamber. The design consisted of a narrow straight channel connected to a trapezoidal channel which widens to another straight channel. Since two designs were made for the computer simulations, the chamber design was just inverted to serve as the second channel design for experimentation. This makes the channel design have a wide straight channel connected to a trapezoidal channel narrowing to another straight channel. The number of particles before and after the junction was recorded. The ratio between the number of particles after and before the junction was then obtained. The results for the first design proved the computer simulations to be correct due to the decrease in the ratio of the number of particles in the middle part of the channel. The results for the second design proved the laminar chaos phenomena due to the random values for the ratios of the number of particles obtained.

Index Terms

channel structure, computational fluid dynamics, junction, laminar flow, microfluidics, particle transport

Abstract

The assessment of the water quality and mercury determination in Talabaan river in Naawan, Misamis Oriental, Philippines was conducted to evaluate the post-mining condition of the water resource. Four sampling points were established including a control area to have a reference value for the portion of the river that is not affected by the tributary from the mine site. The parameters that were assessed include Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS), Chloride, water pH, water temperature, Total Dissolved Solids (TDS) and Dissolved Oxygen (DO). Results of the study showed that mercury on the water resource left no trace from the extraction of gold using amalgamation. Other parameters are in conformity with the standards set by the Department of Environment and Natural Resources (DENR) for Class A water resource or water bodies suitable as water supply which requires conventional treatment. WhilebBOD has exceeded the accepted value under the Philippine National Standard, the values obtained are still considered suitable for water consumption under the standards set by the World Health Organization (WHO). The results strongly suggest that the once active mine operation in the area no longer affected the water quality of Talabaan river.

Index Terms

mercury, Talabaan River, physicochemical, water quality, water assessment

Abstract

The postmodernist leverage of science has motivated many scientists to unravel prevalent technologies that could stipulate our demands. The advancement of two-dimensional materials has unleashed a new era for nanoelectronic devices. Silicene is a very fascinating 2D material that is expected to infill the obstacles encountered in Graphene. Due to its remarkable properties, there has been an intensive immersion of researches to synthesize more on its capabilities. Silicene has been tested to be firm with many elements but none has tested N2. Thus, the interaction of N2 molecule to Silicene Nanoribbon (SiNR) has been investigated using Molecular Dynamics Simulation in LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator). The Si-Si bond is modeled using the Tersoff Potential while the Si-N bond is modeled through the Lennard Jones Potential. In this study, the N2 molecule is placed on the H, B and T sites of the nanoribbon and the energy barriers for the diffusion and formation of N2 on SiNR have been calculated. Also, by employing the Langmuir – Hinshelwood mechanism, the interaction has confirmed the stability of N2 in molecular form.

Index Terms

Graphene, Langmuir – Hinshelwood mechanism, Molecular Dynamics Silicene, Tersoff Potential

Abstract

Disposal of both mine tailings and coal fly ash are continually challenging mining and metal industries to lessen its adverse environmental impacts. Geopolymerization as a co-disposal technique of mining and industrial waste has been used as construction material and to stabilize heavy metals. This study intends to evaluate the durability and leaching behavior of fly ash modified mine tailings-based geopolymer by measuring compression strength and concentration of heavy metals such as Cd, Cr, Pb, Mn and Hg after dissolution simulated in landfill conditions. The effect of Si/Al ratio and NaOH concentration on the mechanical properties of geopolymer was also investigated. Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) imaging was conducted to investigate microstructure and X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses to study the phase compositions of the geopolymer. Heavy metal concentrations were determined using Atomic Absorption Spectroscopy (AAS). Results showed that the Si/Al ratio and NaOH concentration have significant effects on the compressive strength of the fly ash modified mine tailings-based geopolymer. The geopolymer also showed a high efficiency of heavy metals immobilization.

Index Terms

Coal fly ash, mine tailings, geopolymer, immobilization