973 research outputs found

    Design of an Exhaust System For The UTP Formula SAE Race Car

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    The society of Automotive Engineers holds an annual formula car competition for college across the world. To maximise the performance of the Universiti Tekbologi Petronas 's FSAE team car,an avenue of optimizing the air flow out of the engine is needed to enable the combustion process to take place efficiently and effectively. To determine the possible methods of increasing airflow ,theoretical calculations ,software analysis and validation testing will be used.This report includes the basic concepts of the exhausts system of common vehicles and its theories affecting the engine performance. Aside from complying with FSAE rules ,the design criterions should be considered to enable integration of the engine,intake system and other components

    Synthesis of Interface-Driven Tunable Bandgap Metal Oxides

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    Mixed bandgap and bandgap tunability in semiconductors is critical in expanding their use. Composition alterations through single-crystal epitaxial growth and the formation of multilayer tandem structures are often employed to achieve mixed bandgaps, albeit with limited tunability. Herein, self-assembled one-dimensional coordination polymers provide facile synthons and templates for graphitic C-doped mesoporous oxides, gC-β-Ga2O3 or gC-In2O3 via controlled oxidative ligand ablation. These materials have mixed bandgaps and colors, depending on amount of gC present. The carbon/oxide interface leads to induced gap states, hence, a stoichiometrically tunable band structure. Structurally, a multiscale porous network percolating throughout the material is realized. The nature of the heat treatment and the top-down process allows for facile tunability and the formation of mixed bandgap metal oxides through controlled carbon deposition. As a proof of concept, gC-β-Ga2O3 was utilized as a photocatalyst for CO2 reduction, which demonstrated excellent conversion rates into CH4 and CO

    Effect of Casting and Mould Cooling Temperatures on the Warping Phenomenon of Aluminium at High Pressure Die- Casting

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    Abstract. The effect of molten aluminium pouring temperature and hot oiltemperature for mould heating and cooling on the warping phenomenon ofthick-thin section aluminium high-pressure die-casting process was investigatedon a four cavities hard disk drive mould. Nine combinations of moltenaluminium A380 pouring temperature of 660ºC, 690ºC and 720ºC and hot oiltemperature of 150ºC, 200ºC and 250ºC were being studied. Magmasoftsimulation software was used to simulate the molten aluminium flow in themould and distortion to understand the die-casting cooling pattern in responseto different molten aluminium temperature and mould cooling parameterssettings. Actual casting was carried out to produce the parts according tosimulation settings. Warping data was collected and analysed using Minitab 17.It was found that each mould cavity had different cooling pattern resulting indifferent warping magnitude. Pouring temperature at 660ºC and 720ºC both hadhigher warping distortion then 690ºC. Hot oil temperature at 150ºC had higherwarping distortion than 200ºC and 250ºC. The lowest warping distortion wasestablish at molten aluminium pouring and hot oil temperature of 690ºC and200ºC respectively

    A metal-organic framework with ultrahigh glass-forming ability

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    Glass-forming ability (GFA) is the ability of a liquid to avoid crystallization during cooling. Metal-organic frameworks (MOFs) are a new class of glass formers (1?3), with hitherto unknown dynamic and thermodynamic properties. We report the discovery of a new series of tetrahedral glass systems, zeolitic imidazolate framework?62 (ZIF-62) [Zn(Im2?xbImx)], which have ultrahigh GFA, superior to any other known glass formers. This ultrahigh GFA is evidenced by a high viscosity ? (105 Pa?s) at the melting temperature Tm, a large crystal-glass network density deficit (??/?g)network, no crystallization in supercooled region on laboratory time scales, a low fragility (m = 23), an extremely high Poisson?s ratio (? = 0.45), and the highest Tg/Tm ratio (0.84) ever reported. Tm and Tg both increase with benzimidazolate (bIm) content but retain the same ultrahigh Tg/Tm ratio, owing to high steric hindrance and frustrated network dynamics and also to the unusually low enthalpy and entropy typical of the soft and flexible nature of MOFs. On the basis of these versatile properties, we explain the exceptional GFA of the ZIF-62 systempublishersversionPeer reviewe

    Down but not out in posterior cingulate cortex : Deactivation yet functional coupling with prefrontal cortex during demanding semantic cognition

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    The posterior cingulate cortex (pCC) often deactivates during complex tasks, and at rest is often only weakly correlated with regions that play a general role in the control of cognition. These observations led to the hypothesis that pCC contributes to automatic aspects of memory retrieval and cognition. Recent work, however, has suggested that the pCC may support both automatic and controlled forms of memory processing and may do so by changing its communication with regions that are important in the control of cognition across multiple domains. The current study examined these alternative views by characterising the functional coupling of the pCC in easy semantic decisions (based on strong global associations) and in harder semantic tasks (matching words on the basis of specific non-dominant features). Increasingly difficult semantic decisions led to the expected pattern of deactivation in the pCC; however, psychophysiological interaction analysis revealed that, under these conditions, the pCC exhibited greater connectivity with dorsolateral prefrontal cortex (PFC), relative to both easier semantic decisions and to a period of rest. In a second experiment using different participants, we found that functional coupling at rest between the pCC and the same region of dorsolateral PFC was stronger for participants who were more efficient at semantic tasks when assessed in a subsequent laboratory session. Thus, although overall levels of activity in the pCC are reduced during external tasks, this region may show greater coupling with executive control regions when information is retrieved from memory in a goal-directed manner

    Clear Genetic Distinctiveness between Human- and Pig-Derived Trichuris Based on Analyses of Mitochondrial Datasets

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    The whipworm, Trichuris trichiura, causes trichuriasis in ∼600 million people worldwide, mainly in developing countries. Whipworms also infect other animal hosts, including pigs (T. suis), dogs (T. vulpis) and non-human primates, and cause disease in these hosts, which is similar to trichuriasis of humans. Although Trichuris species are considered to be host specific, there has been considerable controversy, over the years, as to whether T. trichiura and T. suis are the same or distinct species. Here, we characterised the entire mitochondrial genomes of human-derived Trichuris and pig-derived Trichuris, compared them and then tested the hypothesis that the parasites from these two host species are genetically distinct in a phylogenetic analysis of the sequence data. Taken together, the findings support the proposal that T. trichiura and T. suis are separate species, consistent with previous data for nuclear ribosomal DNA. Using molecular analytical tools, employing genetic markers defined herein, future work should conduct large-scale studies to establish whether T. trichiura is found in pigs and T. suis in humans in endemic regions
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