Deionized Water Electrochemical Machining Hybridized with Alumina Powder Polishing for Microcavity of M-333 Mold Steel

An electrochemical machining (ECM) process for microcavity fabrication with deionized water (DI-water) and an ECM polishing hybrid with alumina powder of 1.0 μm grains on a single micro-EDM machine are proposed. The process adopts tungsten carbide as tool electrode and M-333 tool steel as the mold material. It reveals that employing the 30 μm/min feed rate with 50 mA and 0.2 ms of pulse-width is suitable for DI-water electrochemical machining. The DI-water ECM process can achieve an excellent surface roughness at Ra 0.169 µm on a semispherical round cavity. Combining the ECM with hybrid polishing with the alumina powder can achieve a better profile for a much deeper cavity than pure electrolytic discharge machining. The hybrid ECM polishing can efficiently finish a micro square insert of 0.6 mm length at 64 μm depth. Such ECM milling can achieve an S-shaped microchannel of radius 1.0 mm and a slot of 1.0 × 0.5 mm2 with 110 μm depth, demonstrating its feasibility and the surface integrity with accurate profile and roughness of Ra 0.227 μm. This study provides a cost-effective scheme for micro mold fabrication with a conventional micro-EDM machine tool and an intuitive and convenient optional process. However, some micro-electrical discharges occurred due to the breakdown of insulation, which creates micro craters on the surface of the parts.

Characterization and Analysis of Malaysian Macroalgae Biomass as Potential Feedstock for Bio-Oil Production

The potential of Caulerpa lentillifera, Gracilaria coronopifolia and Chaetomorpha linum, as biomass feedstock was investigated in this study. It was concluded that seaweed is more suitable for bio-based products synthesis, i.e., bioplastic and bio-lubricants, instead of biofuels due to its relatively low calorific value (~12 MJ/kg). Since seaweed has high moisture content (~80%), hydrothermal liquefaction is recommended, and its efficiency can be further enhanced through microwave technology. Besides, it is found that the thermal degradation of seaweed was best described with the reaction order of 1. The kinetic results also indicated that seaweed consists of lower activation energy (<30 kJ/mol) in comparison with terrestrial biomass (50–170 kJ/mol). Hence, seaweed has a high potential to be used as biomass feedstock, particularly Chaetomorpha linum, as it has no conflict with other interests. Lastly, acetic-acid pre-treatment was suggested to be an optional process in order to increase the algal conversion efficiency as it can reduce up to 25% of ash content.

A note on Modern Hebrew voicing assimilation

In Hebrew, consecutive obstruents that differ in voicing can be produced with the same voicing. This process is regressive as the first obstruent assimilates to the obstruent following it. It is also an optional process as it is dependent on the rate of speech and the formality of the utterance (Bolozky 1978, 1997). Using elicited data, an acoustic study on intervocalic obstruent sequences in Hebrew (Mizrachi 2016) has recently shown that assimilation-to-voiceless is more frequent than assimilation-to-voiced. Moreover, not only does devoicing assimilation occur more often, but it also occurs progressively—at least in terms of vocal fold vibration—in more cases than suggested in previous work.

Local optionality with partial orders

In local optionality, an optional process may apply at some loci in a form but not at others. Some theories of optionality, such as Partial Orders Theory, produce optionality by making multiple strict constraint rankings available, and have been claimed to be incompatible with local optionality: if the process-triggering constraint outranks faithfulness, the process applies exhaustively; under the opposite ranking, it applies nowhere. On this view, candidates in which the process applies at some loci but not others are harmonically bounded. This paper argues against that position by showing that for a variety of locally optional processes each locus can be independently manipulated if the theory makes use of constraints that target particular prosodic or morphosyntactic units – constraints that are motivated independently of their utility in local optionality. The result is that, contrary to the harmonic-bounding argument, Partial Orders Theory can provide plausible accounts of local optionality.