Browsing by Author "Chen, R"

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    ItemOpen Access
    Dark Energy Survey Year 3 Results: Cosmological Constraints from Galaxy Clustering and Weak Lensing
    (arXiv e-prints, 2021-05) Collaboration, DES; Abbott, TMC; Aguena, M; Alarcon, A; Allam, S; Alves, O; Amon, A; Andrade-Oliveira, F; Annis, J; Avila, S; Bacon, D; Baxter, E; Bechtol, K; Becker, MR; Bernstein, GM; Bhargava, S; Birrer, S; Blazek, J; Brandao-Souza, A; Bridle, SL; Brooks, D; Buckley-Geer, E; Burke, DL; Camacho, H; Campos, A; Carnero Rosell, A; Carrasco Kind, M; Carretero, J; Castander, FJ; Cawthon, R; Chang, C; Chen, A; Chen, R; Choi, A; Conselice, C; Cordero, J; Costanzi, M; Crocce, M; da Costa, LN; da Silva Pereira, ME; Davis, C; Davis, TM; De Vicente, J; DeRose, J; Desai, S; Di Valentino, E; Diehl, HT; Dietrich, JP; Dodelson, S; Doel, P; Doux, C; Drlica-Wagner, A; Eckert, K; Eifler, TF; Elsner, F; Elvin-Poole, J; Everett, S; Evrard, AE; Fang, X; Farahi, A; Fernandez, E; Ferrero, I; Ferté, A; Fosalba, P; Friedrich, O; Frieman, J; García-Bellido, J; Gatti, M; Gaztanaga, E; Gerdes, DW; Giannantonio, T; Giannini, G; Gruen, D; Gruendl, RA; Gschwend, J; Gutierrez, G; Harrison, I; Hartley, WG; Herner, K; Hinton, SR; Hollowood, DL; Honscheid, K; Hoyle, B; Huff, EM; Huterer, D; Jain, B; James, DJ; Jarvis, M; Jeffrey, N; Jeltema, T; Kovacs, A; Krause, E; Kron, R; Kuehn, K; Kuropatkin, N; Lahav, O; Leget, P-F; Lemos, P; Liddle, AR; Lidman, C; Lima, M; Lin, H; MacCrann, N; Maia, MAG; Marshall, JL; Martini, P; McCullough, J; Melchior, P; Mena-Fernández, J; Menanteau, F; Miquel, R; Mohr, JJ; Morgan, R; Muir, J; Myles, J; Nadathur, S; Navarro-Alsina, A; Nichol, RC; Ogando, RLC; Omori, Y; Palmese, A; Pandey, S; Park, Y; Paz-Chinchón, F; Petravick, D; Pieres, A; Plazas Malagón, AA; Porredon, A; Prat, J; Raveri, M; Rodriguez-Monroy, M; Rollins, RP; Romer, AK; Roodman, A; Rosenfeld, R; Ross, AJ; Rykoff, ES; Samuroff, S; Sánchez, C; Sanchez, E; Sanchez, J; Sanchez Cid, D; Scarpine, V; Schubnell, M; Scolnic, D; Secco, LF; Serrano, S; Sevilla-Noarbe, I; Sheldon, E; Shin, T; Smith, M; Soares-Santos, M; Suchyta, E; Swanson, MEC; Tabbutt, M; Tarle, G; Thomas, D; To, C; Troja, A; Troxel, MA; Tucker, DL; Tutusaus, I; Varga, TN; Walker, AR; Weaverdyck, N; Weller, J; Yanny, B; Yin, B; Zhang, Y; Zuntz, J
    We present the first cosmology results from large-scale structure in the Dark Energy Survey (DES) spanning 5000 deg$^2$. We perform an analysis combining three two-point correlation functions (3$\times$2pt): (i) cosmic shear using 100 million source galaxies, (ii) galaxy clustering, and (iii) the cross-correlation of source galaxy shear with lens galaxy positions. The analysis was designed to mitigate confirmation or observer bias; we describe specific changes made to the lens galaxy sample following unblinding of the results. We model the data within the flat $\Lambda$CDM and $w$CDM cosmological models. We find consistent cosmological results between the three two-point correlation functions; their combination yields clustering amplitude $S_8=0.776^{+0.017}_{-0.017}$ and matter density $\Omega_{\mathrm{m}} = 0.339^{+0.032}_{-0.031}$ in $\Lambda$CDM, mean with 68% confidence limits; $S_8=0.775^{+0.026}_{-0.024}$, $\Omega_{\mathrm{m}} = 0.352^{+0.035}_{-0.041}$, and dark energy equation-of-state parameter $w=-0.98^{+0.32}_{-0.20}$ in $w$CDM. This combination of DES data is consistent with the prediction of the model favored by the Planck 2018 cosmic microwave background (CMB) primary anisotropy data, which is quantified with a probability-to-exceed $p=0.13$ to $0.48$. When combining DES 3$\times$2pt data with available baryon acoustic oscillation, redshift-space distortion, and type Ia supernovae data, we find $p=0.34$. Combining all of these data sets with Planck CMB lensing yields joint parameter constraints of $S_8 = 0.812^{+0.008}_{-0.008}$, $\Omega_{\mathrm{m}} = 0.306^{+0.004}_{-0.005}$, $h=0.680^{+0.004}_{-0.003}$, and $\sum m_{\nu}<0.13 \;\mathrm{eV\; (95\% \;CL)}$ in $\Lambda$CDM; $S_8 = 0.812^{+0.008}_{-0.008}$, $\Omega_{\mathrm{m}} = 0.302^{+0.006}_{-0.006}$, $h=0.687^{+0.006}_{-0.007}$, and $w=-1.031^{+0.030}_{-0.027}$ in $w$CDM. (abridged)
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    ItemOpen Access
    The evolution of helicopters
    (Journal of Applied Physics, 2016-07-07) Chen, R; Wen, CY; Lorente, S; Bejan, A
    Here, we show that during their half-century history, helicopters have been evolving into geometrically similar architectures with surprisingly sharp correlations between dimensions, performance, and body size. For example, proportionalities emerge between body size, engine size, and the fuel load. Furthermore, the engine efficiency increases with the engine size, and the propeller radius is roughly the same as the length scale of the whole body. These trends are in accord with the constructal law, which accounts for the engine efficiency trend and the proportionality between "motor" size and body size in animals and vehicles. These body-size effects are qualitatively the same as those uncovered earlier for the evolution of aircraft. The present study adds to this theoretical body of research the evolutionary design of all technologies [A. Bejan, The Physics of Life: The Evolution of Everything (St. Martin's Press, New York, 2016)].