Analisis Pengaruh Suhu Mesin terhadap Emisi Gas Buang pada Kondisi Torsi dan Daya Maksimum Studi Kasus: Sepeda Motor Yamaha Vega Zr

Reaksi pembakaran bahan bakar bensin (C8H18) dengan oksigen (O2) dalam keadaan sempurna akan menghasilkan karbondioksida (CO2) dan uap air (H2O) murni. Tetapi karena bensin merupakan campuran senyawa hidrokarbon yang diikuti oleh unsur-unsur lainnya sedemikian rupa dalam proses pembakaran yang begitu singkat akan terjadi hasil unsur dan senyawa lainnya. Pada pengujian emisi gas buang biasanya yang dideteksi adalah senyawa dari unsur C, H dan N. Unsur Nitrogen perlu diamati karena merupakan kandungan udara terbesar yang melebihi Oksigen. Pada penelitian ini akan dilakukan pengamatan terhadap emisi gas buang pada kondisi torsi maksimum dan daya maksimum dengan memvariasikan suhu (temperatur) mesin. Senyawa yang diamati konsentrasinya adalah CO, CO2, HC dan O2. Torsi maksimum terjadi pada putaran rendah sedang daya masimum terjadi pada putaran yang lebih tinggi. Hasil percobaan memperlihatkan konsentrasi gas buang naik dengan naiknya temperatur, kecuali konsentrasi CO2. Konsentrasi CO dan HC lebih tinggi pada kondisi Torsi maksimum, sebaliknya untuk konsentrasi CO2 dan O2

Submilliamp threshold InGaAs-GaAs strained layer quantum-well laser

Strained-layer InGaAs-GaAs single-quantum-well buried-heterostructure lasers were fabricated by a hybrid beam epitaxy and liquid-phase epitaxy technique. Very low threshold currents, 2.4 mA for an uncoated laser (L=425 μm) and 0.75 mA for a coated laser (R~0.9, L=198 μm), were obtained. A 3-dB modulation bandwidth of 7.6 GHz was demonstrated at low bias current (14 mA). Procedures for material preparation and device fabrication are introduced

Parametric study of cavity length and mirror reflectivity in ultralow threshold quantum well InGaAs/AlGaAs lasers

Record low CW threshold currents of 16 μA at-room temperature and 21 μA at cryogenic temperature have been demonstrated in buried heterostructure strained layer, single quantum well InGaAs/AlGaAs lasers with a short cavity length and high reflectivity coatings

Experimental Models for Analysis of Oligodendrocyte Pathophysiology in Stroke

White matter damage is a clinically important part of stroke. However, compared to the mechanisms of neuronal injury in gray matter, white matter pathophysiology remains relatively understudied and poorly understood. This mini-review aims at summarizing current knowledge on experimental systems for analyzing the role of white matter injury relevant to stroke. In vitro platforms comprise primary cultures of both mature oligodendrocytes (OLGs) as well as oligodendrocyte precursor cells (OPCs). Tissue platforms involve preparations of optic nerve systems. Whole-animal platforms comprise in vivo models of cerebral ischemia that attempt to target white matter brain areas. While there is no single perfect model system, the collection of these experimental approaches have recently allowed a better understanding of the molecular and cellular pathways underlying OLG/OPC damage and demyelination. A systematic utilization of these cell, tissue and whole-animal platforms may eventually lead us to discover new targets for treating white matter injury in stroke and other CNS disorders

Very High Modulation Efficiency of Ultralow Threshold Current Single Quantum Well InGaAs Lasers

A record high current modulation efficiency of 5 GHz/[sqrt](mA) has been demonstrated in an ultralow threshold strained layer single quantum well InGaAs laser

Integer quantum Hall effect on a six valley hydrogen-passivated silicon (111) surface

We report magneto-transport studies of a two-dimensional electron system formed in an inversion layer at the interface between a hydrogen-passivated Si(111) surface and vacuum. Measurements in the integer quantum Hall regime demonstrate the expected sixfold valley degeneracy for these surfaces is broken, resulting in an unequal occupation of the six valleys and anisotropy in the resistance. We hypothesize the misorientation of Si surface breaks the valley states into three unequally spaced pairs, but the observation of odd filling factors, is difficult to reconcile with non-interacting electron theory.Comment: 4 pages, 4 figures, to appear in Physical Review Letter

A novel technique for the direct determination of carrier diffusion lengths in GaAs/AlGaAs heterostructures using cathodoluminescence

A new technique for determining carrier diffusion lengths in direct gap semiconductors by cathodoluminescence measurement is presented. Ambipolar diffusion lengths are determined for GaAs quantum well material, bulk GaAs, and Al_xGa_(1-x)As with x up to 0.38. A large increase in the diffusion length is found as x approaches 0.38 and is attributed to an order of magnitude increase in lifetime