MEMBANGUN MODEL DINAMIS PENANGKARAN POPULASI MALEO (Macrochepalon Maleo) YANG MEMPERTAHANKAN EKSISTENSINYA DARI PREDATOR

Maleo (Macrocephalon maleo) is one of the endangered endemic species of Sulawesi due to diminishing spawning habitat, community exploitation and predators. The dynamic model of maleo population captivity to conserve its existence from predators is a mathematical model that describes the dynamics of maleo population growth cycle (M) with the threat of predators (P). In this study, the population of eggs maleo divided into two groups that are eggs in the free zone (Tb) and eggs in breeding (Tp). The eggs are in the captive breeding will be transfered to the exposure group (E). The model represents the interaction between the predators and populations reflecting maleo in each growth phase. The model has two critical points, namely the critical point 𝑇1 = ( 0,0,0,0, 𝜑 µ2 ) describing maleo extinction condition and critical point 𝑇2 = (𝑀∗ , 𝑇𝑝∗ ,𝐸 ∗ , 𝑇𝑏∗ , 𝑃 ∗ ) which describes the endemic conditions of maleo growth dynamics. The stability analysis shows that the system is unstable at both critical points. It is because the values of the first column in the Routh Hurwitz table changes in sign. Simulations of the endemic conditions showed that the maleo and egg populations in the free zone are decreasing with respect to time even though the exposed maleo still exist. The unstable endemic indicates that the existence of maleo breeding program in conservation areas still need another efforts support.

The Effect of Water Droplet Size on the Extinguished Concentric Jet Premixed and Diffusion Flame

The present research experimentally investigated the effect of different water droplet size on the burning behavior and extinction condition of concentric jet premixed and diffusion flame. Water droplet stream in line with flowing air from lower duct. The burning behavior of concentric jet flame was observed and the extinction of flame was gained by decreasing the flow rate of fuel until the flame exthinguised. The results showed that the burning behavior of concentric jet diffusion and premixed flame had the same tendency. Different water droplet size influenced the burning behavior of flame. Decreasing the water droplet size, luminosity of the flame became thin as well as reducing the flame height. However, the inhibition effect of water droplet was stronger for diffusion flame compared to premixed flame. For smaller water droplet size, water droplet was four times more effective for suppressing the diffusion flame than premixed flame

Hafnium-Silicon Precipitate Structure Determination in a New Heat-Resistant Ferritic Alloy by Precession Electron Diffraction Techniques

The structure determination of an HfSi4 precipitate has been carried out by a combination of two precession electron diffraction techniques: high precession angle, 2.2°, single pattern collection at eight different zone axes and low precession angle, 0.5°, serial collection of patterns obtained by increasing tilts of 1°. A three-dimensional reconstruction of the associated reciprocal space shows an orthorhombic unit cell with parameters a = 11.4 Å, b = 11.8 Å, c = 14.6 Å, and an extinction condition of (hkl) h + k odd. The merged intensities from the high angle precession patterns have been symmetry tested for possible space groups (SG) fulfilling this condition and a best symmetrization residual found at 18% for SG 65 Cmmm. Use of the SIR2011 direct methods program allowed solving the structure with a structure residual of 18%. The precipitate objects of this study were reproducibly found in a newly implemented alloy, designed according to molecular orbital theory.

Local Quenching Recovery Processes of Premixed and Diffusion Interacting Flames in a Turbulent Opposite Flow

A lean premixed CH4 air flame (LPF) impinges with a CH4 diluted with N2 diffusion flame (DF) having different turbulence conditions to create a lean heterogeneous combustion model such as a stratified combustion. The local quenching recovery processes of LPF and DF interacting with the turbulence in an opposed flow have been investigated experimentally using a Particle Image Velocimetry movie. The local quenching phenomena can be observed frequently with approaching the global extinction condition. The local quenching may trigger to global extinction. However, in many cases, the flame can recover from the local quenching phenomena and create the stable flame. There are three distinct local quenching recovery mechanisms namely a passive mode, an active mode, and an eddy transportation mode. These three modes depend on the local flame propagation mechanism, the bulk flow motion, and the eddy motion by turbulence. In the passive mode, the bulk flow plays an important role on the recovery process. The local quenching area is drifting outward from the stabilization point by the bulk flow and then, it is displaced by the stable flamelets. In the active mode, the local quenching area is recovered by the self-propagating wrinkled LPF from somewhere in the active zone. The active mode is observed only when the turbulence is added to the premixed flame side. In the eddy motion mode, the local quenching area is recovered by the eddy transportation. That is, the flamelet is transport by the eddy motion and the local quenching area is replaced. The wrinkled flamelet having self-propagation plays a very important role for the local quenching recovery mechanism. The turbulence on the premixed flame not only induces high possibility for the local quenching but also helps to recover from the local quenching.

Flame Spread Along PE-Insulated Wire in Sub-Atmospheric Pressure Enclosure

Flame spread over polymer-insulated wire in reduced (sub-atmospheric) pressure has been studied experimentally in order to evaluate the fire safety of electric circuit in the aircraft as well as the space habitats. Polyethylene (PE) insulated NiCr wire is used as the burning sample. Ambient gas is the mixture of nitrogen and oxygen, and the composition is fixed as air (79 vol.% of N2 and 21 vol.% of O2) throughout the study. Total pressure is reduced from atmospheric (101 kPa) to sub-atmospheric (20 kPa) in order to investigate the role of the reduced pressure on the flame spread along the wire. Spread event followed by the forced ignition is recorded by digital video camera to obtain any time-dependent flame behavior. Experimental results show that the flame shape is changed from typical “teardrop” to “round” (and even oval) with the decrease in total pressure. Flame spread rate increases in the reduced pressure although the partial pressure of oxygen is “reduced” with the total pressure. Such “pronounced” spread behavior is continuously observed until just before the extinction condition (∼25 kPa in the present study). The change in flame shape could enhance thermal input to the unburned PE through gas-phase conduction as well as conduction along the wire, and these should be responsible for the faster flame spread in sub-atmospheric pressure. Heat balance is roughly estimated with measured temperature and relative contribution of above two thermal input pathways is understood almost comparable. Importance of the presence of conductive material, such as metal wire, on flame spread is addressed in the current spread behavior.