PENGARUH MODEL PEMBELAJARAN POE TERHADAP KEMAMPUAN PEMAHAMAN KONSEP IPA SISWA SD

ABSTRAKPenelitian ini bertujuan untuk mengetahui pengaruh penggunaan model pembelajaran POE (Predict, Observe, Explain) terhadap kemampuan pemahaman konsep IPA siswa pada materi panas dan perpindahannya. Penelitian ini dilaksanakan di MIS Ushuluddin Singkawang. Jenis penelitian yang digunakan yaitu penelitian kuantitatif dengan metode quasi experimental design, dengan bentuk desain post-test only control design. Populasi dalam penelitian ini adalah seluruh siswa kelas V MIS Ushuluddin Singkawang. Sampel diambil menggunakan teknik purposive sampling. Setelah pengambilan sampel, yang terpilih menjadi kelas eksperimen adalah kelas VA dengan menggunakan model pembelajaran POE dan VB sebagai kelas kontrol yang menggunakan model pembelajaran langsung. Hasil penelitian menunjukkan bahwa: (1) Terdapat pengaruh kemampuan pemahaman konsep IPA siswa antara kelas yang diberikan model pembelajaran POE dengan kelas yang diberikan pembelajaran langsung pada materi panas dan perpindahannya di kelas V MIS Ushuluddin Singkawang; (2) Terdapat perbedaan kemampuan pemahaman konsep IPA siswa antara kelas yang diberikan model pembelajaran POE dengan kelas yang di berikan model pembelajaran langsung pada materi panas dan perpindahannya di kelas V MIS Ushuluddin Singkawang. Kata kunci: model pembelajaran POE; kemampuan pemahaman konsep. ABSTRACTThis study is aimed at learning the influence of the use of the POE learning model (Predict, Observe, Explain) on a student's ability to understand science concepts on hot matter and transmigration. The study is carried out at MIS Ushuluddin Singkawang. The kind of research used was quantitative research with experimental quasi design. With a design post-test only design control. The population in the study are all the students in the V MIS Ushuluddin Singkawang class. The sample was taken using an additive sampling, after taking the selected sample into a VA class experiment which was an experimental class using the POE and VB control class that use a direct learning model. Research concluded that: (1) there is an influence on a student's ability to understand natural science between a class given by the POE learning model and a class given direct learning on hot matter and transfer to V MIS Ushuluddin Singkawang class; (2) there is a difference in the ability to understand a student science concept between the class given by the POE learning model and the class provided the direct learning model for hot matter and transfer to V MIS Ushuluddin Singkawang class. Keywords: POE learning models; the ability to understand concepts.

Modeling the Dynamics of Heavy-Ion Collisions with a Hydrodynamic Model Using a Graphics Processor

Dense bulk matter is formed during heavy-ion collision and expands towards a vacuum. It behaves as a perfect fluid, described by relativistic hydrodynamics. In order to study initial condition fluctuation and properties of jet propagation in dense hot matter, we assume a Cartesian laboratory frame with several million cells in a stencil with high-accuracy data volume grids. Employing numerical algorithms to solve hydrodynamic equations in such an assumption requires a lot of computing power. Hydrodynamic simulations of nucleus + nucleus interactions in the range of energies of the Large Hadron Collider (LHC) are carried out using our program, which uses Graphics Processing Units (GPUs) and Compute Unified Device Architecture (CUDA). In this work, we focused on transforming hydrodynamic quantities into kinetic descriptions. We implemented the hypersurface freeze-out conditions using marching cubes techniques. We developed freeze-out procedures to obtain the momentum distributions of particles on the hypersurface. The final particle distributions, elliptic flow, and higher harmonics are comparable to the experimental LHC data.

Is breaking through matter a hot matter? How to predict material failure by monitoring creep

<p>In any domain involving some stressed solids, that is, from seismology to rock physics or general engineering, the strength of matter is a paramount feature to understand.  The global failure of a mechanically loaded solid is usually dictated by the growth of its internal micro-cracks and dislocations. When this growth is rather smooth and distributed, the solid is considered to be in ductile condition. Alternatively, an abrupt propagation of localized defects leads to a brittle rupture of the full matrix.<br>It is then critical to understand what the physics and dynamics of isolated cracks are, when their tips are loaded at a given stress level. While the general elasticity theory predicts such stress to diverge, it is  acknowledged that some area around the crack fronts is rather plastic. In other words, some dissipation of mechanical energy, in a so-called process zone around a crack tip, prevents the - unphysical - stress divergence and shields the fronts from excessive load levels.</p><p>In this work, we focus on the local Joule heating, that significantly contributes to the energy dissipation. Analysing experimental data of the rupture of many materials, we indeed show that the scale for the thermal release around crack tips explains why the toughness of different media spans over orders of magnitude (we analysed materials spanning over 5 decades of energy release rate), whereas the covalent energy to separate two atoms does not.</p><p>We here discuss the ability of this simple thermally activated sub-critical model, which includes the auto-induced thermal evolution of crack stips [1], to predict the catastrophic failure of a vast range of materials [2]. It is in particular shown that the intrinsic surface energy barrier, for breaking the atomic bonds of many solids, can be easily deduced from the slow creeping dynamics of a crack. This intrinsic barrier is however higher than the macroscopic load threshold at which brittle matter brutally fails, possibly as a result of thermal activation and of a thermal weakening mechanism. We propose a novel method to compute the macroscopic critical energy release rate of rupture, Gc macroscopic, solely from monitoring slow creep, and show that this reproduces the experimental values within 50% accuracy over twenty different materials (such as glass, rocks, polymers, metals), and over more than four decades of fracture energy. We also infer the characteristic energy of rupturing bonds, and the size of an intense heat source zone around crack tips, and show that it scales as the classic process zone size, but is significantly (10<sup>5</sup> to 10<sup>7</sup> times) smaller.</p><p>References:</p><div><span>[1] Vincent-Dospital, T.</span>,<span> Toussaint, R.</span>,<span> Santucci, S.</span>, <span>Vanel, L.</span>,<span> Bonamy, D.</span>,<span> Hattali, L.</span>, Cochard, <span> A</span>, <span>Flekkøy, E.G.</span><span> and </span><span>Måløy, K.J. (2020). How heat controls fracture: the thermodynamics of creeping and avalanching cracks. Soft Matter, 2020, 16, 9590-9602. DOI: 10.1039/D0SM01062F<br></span></div><div> </div><p>[2] Vincent-Dospital, T., Toussaint, R., Cochard, A., Flekkøy, E. G., & Måløy, K. J. (2020). Is breaking through matter a hot matter? A material failure prediction by monitoring creep. <em>arXiv preprint arXiv:2007.04866</em>.  https://arxiv.org/abs/2007.04866</p>

Heavy ion collisions and neutron stars : dynamics and thermodynamics of QCD matter

This thesis deals with the phenomenology of QCD matter, its aspects in heavy ion collisions and in neutron stars. The first half of the work focuses on the hadronic phase of QCD matter. One focus is on how the hadronic phase shows itself in heavy ion collisions and how its dynamics can be simulated. The role of hadronic interactions is considered in the context of the lattice QCD data. The second part of this thesis presents a unified approach to QCD matter, the CMF model. The CMF model incorporates many aspects of QCD phenomenology which allows for a consistent description of the hadron-quark transition, making it applicable to the entire QCD phase diagram, i.e., to the cold nuclear matter and to the hot QCD matter. It is shown that a description of both the hot matter created in heavy ion collisions and the cold dense matter in neutron star interiors is possible within one single approach, the CMF model.

Neutrino Cooling of Primordial Hot Regions

The effect of neutrino cooling of possible primary regions filled by hot matter is discussed. Such regions could be obtained from the primordial density inhomogeneities and survive up to the modern epoch. The inhomogeneities could be caused by a symmetry breaking during the inflationary stage. We show that the final temperature of such region should be ∼10 keV provided that the initial temperature is within the interval 10 keV ÷ 100 MeV. The cooling is realized due to the weak nuclear reactions containing n−p transition. The lower limit 10keV is accounted for by suppression of the reactions rates because of the threshold effect and particle concentration decrease.