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

Doppler-free approach to optical pumping dynamics in the 6S1/2−5D5/26S_{1/2}- 5D_{5/2} electric quadrupole transition of Cesium vapor

The $6S_{1/2}-5D_{5/2}$ electric quadrupole transition is investigated in Cesium vapor at room temperature via nonlinear Doppler-free 6P-6S-5D three-level spectroscopy. Frequency-resolved studies of individual E2 hyperfine lines allow one to analyze optical pumping dynamics, polarization selection rules and line intensities. It opens the way to studies of transfer of light orbital angular momentum to atoms, and the influence of metamaterials on E2 line spectra.Comment: 4 pages, 5 figures, minor updates from previous versio

Coupling of atomic quadrupole transitions with resonant surface plasmons

We report on the coupling of an electric quadrupole transition in atom with plasmonic excitation in a nanostructured metallic metamaterial. The quadrupole transition at 685 nm in the gas of Cesium atoms is optically pumped, while the induced ground state population depletion is probed with light tuned on the strong electric dipole transition at 852 nm. We use selective reflection to resolve the Doppler-free hyperfine structure of Cesium atoms. We observed a strong modification of the reflection spectra at the presence of metamaterial and discuss the role of the spatial variation of the surface plasmon polariton on the quadrupole coupling.Comment: 6 pages, 5 figure

Out of equilibrium electronic transport properties of a misfit cobaltite thin film

We report on transport measurements in a thin film of the 2D misfit Cobaltite $Ca_{3}Co_{4}O_{9}$. Dc magnetoresistance measurements obey the modified variable range hopping law expected for a soft Coulomb gap. When the sample is cooled down, we observe large telegraphic-like fluctuations. At low temperature, these slow fluctuations have non Gaussian statistics, and are stable under a large magnetic field. These results suggest that the low temperature state is a glassy electronic state. Resistance relaxation and memory effects of pure magnetic origin are also observed, but without aging phenomena. This indicates that these magnetic effects are not glassy-like and are not directly coupled to the electronic part.Comment: accepted in Phys Rev B, Brief report

Strongly enhanced effective mass in dilute two-dimensional electron systems: System-independent origin

We measure the effective mass in a dilute two-dimensional electron system in (111)-silicon by analyzing temperature dependence of the Shubnikov-de Haas oscillations in the low-temperature limit. A strong enhancement of the effective mass with decreasing electron density is observed. The mass renormalization as a function of the interaction parameter r_s is in good agreement with that reported for (100)-silicon, which shows that the relative mass enhancement is system- and disorder-independent being determined by electron-electron interactions only.Comment: As publishe

Effect of aggregates with high gypsum content on the performance of concrete

Sulfates in fine aggregate are a major problem when it exists in excessive amount especially in the Middle East and Iraq. Most of sulfate salts in fine aggregate are composed of calcium, magnesium, potassium and sodium sulfates. Calcium sulfates is the most common salt present in fine aggregate. It is usually finding as gypsum. It is difficult to obtain the specific sulfates content in fine aggregate within standard specifications. This research was conducted to investigate the effect of adding different contents of gypsum to fine aggregate as a replacement by weight on some properties of two types of concrete {self-compacted concrete (SCC) and high strength concrete (HSC)}. In these work three bases mixes of each type of concrete are used: mixes with different contents of metakaolin, mixes with different contents of gypsum and mixes incorporating different contents of metakaolin and gypsum. This study is devoted to determine the allowable content of sulfates in fine aggregate. Three levels of gypsum were tested (0.5, 1, 1.5) % by weight of fine aggregate and three levels of metakaolin were tested (5, 10, 15) % by the weight of cement. The experimental program is devoted to produce concrete with different levels of metakaolin and gypsum and determine its mechanical properties such as compressive strength and splitting tensile strength. The results arrived from this work show that the optimum gypsum content was 1.5% by weight of fine aggregates for mixes of SCC which gives increases in compressive strength and tensile strength, and 1% gypsum for mixes of HSC, results showed also that the metakaolin improved the properties of the two types of concrete and increased the loss which caused by sulfates. The best mix ever in SCC is 1% gypsum with 5% metakaolin, and 1% gypsum with 10% metakaolin for HSC