Juliana Zaini

Investigating the impact of tool inertia on machinability of a β-titanium alloy using tool deflection and acoustic emission

Finding sustainable ways of machining exotic materials is gaining more and more importance in the manufacturing industry. Application of advanced measuring instruments for quantifying performance measures is a crucial requirement for making machining processes viable. The presented work aims to ameliorate machining of a high-strength β-titanium alloy using information from measurements of key responses, such as cutting energy consumption, tool deflection, and tool damage. Acoustic emission data and tool’s acceleration data are utilized to work out the magnitudes of energy consumed and deflection undergone by the tool, respectively. The article focuses on quantifying the effects of tool’s inertia, strength of work material, and two cutting parameters on the aforementioned responses. A total of 54 continuous cutting experiments are performed in which a fixed volume of material per experimental run is removed. Tool deflection method helped to determine the significant effects of varying tool inertia, work material strength, and cutting speed on the machining process. Likewise, acoustic emission method highlighted the strong effects of material strength and cutting speed caused on the cutting energy consumption. The effect of feed rate is found to be significant regarding tool wear only. Finally, the tool wear data are tested for correlation against the corresponding data sets of the other two responses. It is found that both tool deflection and cutting energy possess strong uphill relationships with tool wear.

High Power Highly Nonlinear Holey Fiber with Low Confinement Loss for Supercontinuum Light Sources

The high power holey fiber is an efficient supercontinuum light source by using picosecond pulse, which is a less expensive laser source compared with low power and expensive femtosecond laser sources. In this paper, a high power highly nonlinear holey fiber (HN-HF) with a low confinement loss is proposed for supercontinuum light sources. The finite difference method is used to calculate the different properties of the proposed HN-HF. High nonlinear coefficients are obtained at 1.06 μm, 1.31 μm, and 1.55 μm wavelengths with flattened chromatic dispersion and low confinement losses simultaneously. Moreover, numerical simulation results show that high power broad supercontinuum spectra with very short length of the proposed photonic crystal fiber are achieved.

Experimental investigation of energy properties for Stigonematales sp. microalgae as potential biofuel feedstock

ABSTRACT Microalgae has been considered potential biofuel source from the last decade owing to its versatile perspectives such as excellent capability of CO2 capture and sequestration, water treatment, prolific growth rate and enormous energy content. Thus, energy research on microalgae is being harnessed to mitigate CO2 and meet future energy demands. This study investigated the bioenergy potential of native blue-green microalgae consortium as initial energy research on microalgae in Brunei Darussalam. The local species of microalgae were assembled from rainwater drains, the species were identified as Stigonematales sp. and physical properties were characterised. Sundried biomass with moisture content ranging from 6.5% to 7.37% was measured to be used to determine the net and gross calorific value and they were 7.98 MJ/kg-8.57 MJ/kg and 8.70 MJ/kg-9.45 MJ/kg, respectively. Besides that, the hydrogen content, ash content, volatile matter, and bulk density were also experimented and they were 2.56%-3.15%, 43.6%-36.71%, 57–38%-63.29% and 661.2 kg/m3-673.07 kg/m3, respectively. Apart from experimental values, other physical bioenergy parameters were simulated and they were biomass characteristic index 61,822.29 kg/m3-62,341.3 kg/m3, energy density 5.27 GJ/m3-5.76G J/m3 and fuel value index 86.19–88.54. With these experimental results, microalgae manifested itself a potential source of biofuel feedstock for heat and electricity generation, a key tool to bring down the escalated atmospheric greenhouse gases and an alternation for fossil fuel.

YSr2Fe3-xCoxO8 as a Potential Cathode Materials for SOFCs

The composition YSr2Fe3-xCoxO8 (for x = 0.5, 3.0) has been investigated as an alternative cathode material for Solid Oxide Fuel Cells (SOFCs). X-ray diffraction (XRD) pattern shows that the composition YSr2Fe2.5Co0.5O8 crystallizes with cubic symmetry in the space group Pm-3m and YSr2Co3O8 crystallizes with tetragonal symmetry in the space group P4/mmm. Rietveld refinement of XRD data shows the cell parameter of the cubic YSr2Fe2.5Co0.5O8 is a = b = c = 4.1964(2) (Å) and tetragonal YSr2Co3O8 is a = b = 9.8998(9) (Å) and c = 8.9617(6) (Å). Scanning electron microscropy (SEM) images show porous structure for both the samples, which is favourable as a cathode for Solid Oxide Fuel Cells.

Effects of Wetting on the Soil Fabric of Compacted Clay

Saturation-unsaturation process of compacted clay fill may lead to loss of shear strength and collapse compression or heave of the fill. These are the two main engineering problems associated with compacted clay fills and naturally before, granular based compacted fills are often employed at construction sites. Use of granular material for compaction may not be economical and sustainable. Therefore, a laboratory-based study was carried out to examine the structure of the compacted clay when used as backfill material. Several kaolin clay specimens prepared under similar condition were subjected to wetting with and without K0 control.