2,054 research outputs found

    Perencanaan Alat Angkat Kendaraan Niaga Kapasitas 2 Ton

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    Equipment design start from component design. In order to meet the requirements, it is designed base on the material used. The purpose of this study is to design a manually operated lifting equipment of 2 ton capacity used in a commercial vehicles in the form of engineering drawing. Comparison data used in this study is a triple lift floor jack. From the calculations, it is found that the largest load happened a lifting position

    Gambaran Makroskopik Dan Mikroskopik Pankreas Pada Hewan Coba Postmortem

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    : Medicolegal examination is beneficial in police investigation inter alia to determine the time of death and causes as well as mechanisms of death. Postmortem macroscopic and microscopic changes could be alternatives to estimate the time of death. This study was aimed to obtain the microscopic and macroscopic postmortem changes in pancreas based on the variation of time up to 48 hours. This was a descriptive observational study using two domestic pigs as animal model. Pancreas samples were obtained at time intervals as follows: 0 hour, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, 30 hours, 33 hours, 36 hours, 39 hours, 42 hours, and 48 hours postmortem. The macroscopic examination showed changes in its consistency at 8 hours postmortem, followed by changes in color, consistency, and length during 39 hours postmortem. Microscopic changes of pancreas occurred at 2 hours postmortem as congestion of the acini. At 5 hours postmortem, the acinar cells were difficult to be identified; most of their nuclei were distributed out of the cells. At 8 hours postmortem the structures of acini could not be identified and the cells had undergone karyolysis. At 10 hours postmortem the structures of all acini could not be identified. Conclusion: Postmortem macroscopic changes of pancreas began at 8 hours postmortem meanwhile microscopic changes began at 2 hours postmortem as acinar congestion. At 8 hours postmortem most acini's structures could not be identified and their cells' nuclei underwent karyolysis

    Lattice dynamics and vibrational spectra of the orthorhombic, tetragonal and cubic phases of methylammonium lead iodide

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    The hybrid halide perovskite CH3NH3PbI3 exhibits a complex structural behaviour, with successive transitions between orthorhombic, tetragonal and cubic polymorphs at ca. 165 K and 327 K. Herein we report first-principles lattice dynamics (phonon spectrum) for each phase of CH3NH3PbI3. The equilibrium structures compare well to solutions of temperature-dependent powder neutron diffraction. By following the normal modes we calculate infrared and Raman intensities of the vibrations, and compare them to the measurement of a single crystal where the Raman laser is controlled to avoid degradation of the sample. Despite a clear separation in energy between low frequency modes associated with the inorganic PbI3 network and high-frequency modes of the organic CH3NH3+ cation, significant coupling between them is found, which emphasises the interplay between molecular orientation and the corner-sharing octahedral networks in the structural transformations. Soft modes are found at the boundary of the Brillouin zone of the cubic phase, consistent with displacive instabilities and anharmonicity involving tilting of the PbI6 octahedra around room temperature.Comment: 9 pages, 4 figure

    Studi Mengenai Kapasitas Friksi Tiang Pada Tanah Lempung Ekspansif Yang Ditinjau Dari Kadar Air Tanah, Waktu, Dan Material

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    Tanah lempung ekspansif memiliki sifat swelling, yaitu mengembang saat kadar air tinggi dan menyusut saat kadar air rendah. Sifat swelling ini ditentukan oleh mineral yang terkandung di dalam tanah. Penelitian ini membahas seberapa besar Perubahan daya dukung friksi tiang pada saatmengalami Perubahan kadar air, pengistirahatan setelah pemancangan, serta jenis material tiang. Tanah yang diambil merupakan tanah lempung ekspansif di daerah Ciputra pada kedalaman 1 meter. Tanah dikondisikan dalam keadaan undisturb dengan variabel drying 10%, 20%, 30%, 40%, 50%,wetting 2,5%, 5%, 7,5% sebagai penentu kadar air, pengistirahatan selama 1, 2, 5, 10, dan 30 hari digunakan sebagai penentu waktu, sedangkan permodelan tiang baja dan tiang beton digunakan sebagai variabel jenis material. Hasil yang didapat dari percobaan adalah kadar air mempengaruhi kuat geser tanah sampel. Nilai kapasitas friksi tiang mengalami peningkatan seiring dengan penurunan kadar air, karena adanya suction saat kadar air rendah. Selain itu terjadi peningkatan kapasitas friksi tiang seiring dengan lamanya pengistirahatan. Pada kadar air tinggi, peningkatan kapasitas friksi tidak terlalu berarti. Tiang baja memiliki nilai kapasitas friksi yang lebih besar daripada tiang beton. Selain akibat dari permukaan beton berongga, yang menyebabkan luas permukaannya lebih kecil, hisapan pada baja lebih tinggi daripada pada beton

    Density Profiles of Collapsed Rotating Massive Stars Favor Long Gamma-Ray Bursts

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    Long-duration gamma-ray bursts (lGRBs) originate in relativistic collimated outflows -- jets -- that drill their way out of collapsing massive stars. Accurately modeling this process requires realistic stellar profiles for the jets to propagate through and break out of. Most previous studies have used simple power laws or pre-collapse models for massive stars. However, the relevant stellar profile for lGRB models is in fact that of a star after its core has collapsed to form a compact object. To self-consistently compute such a stellar profile, we use the open-source code GR1D to simulate the core-collapse process for a suite of low-metallicity, rotating, massive stellar progenitors that have undergone chemically homogeneous evolution. Our models span a range of zero-age main sequence (ZAMS) masses: MZAMS=13,18,21,25,35,40M_\mathrm{ZAMS} = 13, 18, 21, 25, 35, 40, and 45M45 M_\odot. All of these models, at the onset of core-collapse, feature steep density profiles, ρrα\rho \propto r^{-\alpha} with α2.5\alpha\approx 2.5, which would result in jets that are inconsistent with lGRB observables. We follow the collapse of four out of our seven models until they form BHs and the other three proto-neutron stars (PNSs). We find, across all models, that the density profile outside of the newly-formed BH or PNS is well-represented by a flatter power law with α1.351.55\alpha \approx 1.35{-}1.55. Such flat density profiles are conducive to successful formation and breakout of BH-powered jets and, in fact, required to reproduce observable properties of lGRBs. Future models of lGRBs should be initialized with shallower \textit{post-collapse} stellar profiles like those presented here instead of the much steeper pre-collapse profiles that are typically used.Comment: 9 pages, 4 figures+1 table, submitted to ApJL, comments welcom
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