Volume 8 No. 1September 2012
Evaluation of Sonic Fidelity of Full and Approximated HRTFs With Reverberation From the Sonic Fidelity of Loud Speakers
pp 19-31 (Vol 8 No. 1 2013)
Elson Chiu, Archie Cullano, Garyl Gordiel, Edward Kung and Clement Ong*
Computer Technology Department, College of Computer Studies, De La Salle University 2401 Taft Avenue, Manila, Philippines
The goal of a music playback system is to reproduce as closely as possible the sound experience of live music. Despite the excellent frequency response afforded by smaller, lighter transducers, headphones produce an unnatural “in the head” sound experience that many acute listeners find distracting. Head-related transfer functions (HRTFs) are an individualized summarization of the direction-dependent acoustic filtering a free-field sound undergoes due to a person’s head, torso, and pinna varying as a function of source position and having large intersubject variation. The common acoustical pole and zero (CAPZ) model requires far fewer variable parameters to represent HRTFs. In this study, different approximations of the CAPZ model are processed and evaluated in their ability to emulate the external sound field of loudspeakers while headphones are worn. The subjective results show that there was no audible drop in quality when HRTFs were incorporated to the sound and that no approximation was singled out as having the best sound quality, but it was observed that the amount of balance between the poles and zeros had an
pp 14-18 (Vol 8 No. 1 2013)
Han Ung Lee, Hayan Lee and Wilfredo Credo Chung*
Department of Chemistry, De La Salle University – Manila, 2401 Taft Avenue, Manila, 1004 Philippines
FIESTA—the Filipino Initiative on Electronic Structure Theory and Applications—a new computational chemistry software is developed. The new software is capable of doing ground-state self-consistent field (SCF) single-point restricted Hartree-Fock (RHF) calculation of polyelectronic and polyatomic systems using the Slater-type orbital basis set STO-3G. The new program implements well-known quantum mechanical theories for practical calculations. FIESTA is written using two programming languages, namely C and FORTRAN. It is accurate and user-friendly. It runs efficiently under the Linux operating system and is able to reproduce the energies calculated using well-established standard quantum chemical software products Gaussian, Firefly and Molpro. To our knowledge, FIESTA is the first and only molecular modeling software developed in the Philippines to date. The software will be extended to calculate the properties of systems such as atoms, molecules, ions and formula units using more sophisticated basis sets and quantum mechanical techniques.
Monte Carlo N-Particle Method Dose Calculations Using Gold Nanoparticles in Cobalt-60 Radiation Therapy
pp 8-13 (Vol 8 No. 1 2013)
J.T.P. Cruz 1, A.L. Rodriguez 2, J.D. Trono 3 *
1 St Luke’s College of Medicine – WHQM, Cathedral Heights, Sta. Ignaciana St., Quezon City , Philippines;
2 De La Salle Health Sciences Institute, Congressional Ave., Pasong Lawin, Dasmarinas, Cavite, Philippines; and
3 Physics Department, De La Salle University, 2401 Taft Avenue, Manila, Philippines
In this paper, amplification in dose due to the presence of gold nanoparticles was quantified using Monte Carlo N-Particle (MCNP) simulation. Simulation models included the irradiation of a 30 cm × 30 cm × 15 cm pure-water—volume phantom with a beam of 1.17 MeV and 1.33 MeV Cobalt spectral emissions as source. Planar and concentric water panel detectors placed at a distance of intervals of 0.1 cm from the center and the surface were used to obtain radial and depth doses within. To verify the accuracy of the program codes and the phantom specifications used, baseline data using water phantom were compared to calibration data. Amplification in irradiation of a water phantom with spherical tumor and irradiation of a water phantom with varying concentrations GNP-embedded tumor was also determined. Statistical comparisons were done using analysis of variance (ANOVA) and T-test to determine the relationships among the data parameters garnered. As expected, GNPs amplified radiation dose through photoelectric effect showing an increase of 0.407% for 1 mg/g and 8.54% for 7 mg/g GNP concentrations. 1 mg/g and 7 mg/g GNP concentrations recorded 68.68% and 104.81% difference, respectively, in comparison with planar doses achieved in model B. A percent of difference of 128.51%, on the other hand, was obtained when planar doses of 1 mg/g and 7 mg/g GNP-concentrations were compared.
The Spectra of the Cartesian Product of Some Special Classes of Assymetric, Circulant and r-Regular Digraphs
pp 1-7 (Vol 8 No. 1 2013)
Isagani B. Jos
Department of Mathematics, De La Salle University
Taft Avenue, Manila, Philippines
Two classes of asymmetric, circulant, and r-regular digraphs were deﬁned in . These digraphs are denoted by C r and dCn. The former is an orientation of the rth power of the cycle Cn. Another pair of asymmetric, circulant, and r-regular digraphs were introduced in . One belongs to the class of tournaments, and the other is an orientation of a class of complete bipartite graphs. The former is denoted by Tn, and the latter is denoted by m,m. In  and , the singularity and nonsingularity of these classes of digraphs were investigated. In , the spectra of the aforementioned special classes of digraphs and their complements were determined. A binary operation on digraphs is the cartesian product of digraphs. This paper gives the spectra and establishes some properties of the resulting digraph when the cartesian product of the digraphs given above are obtained.