A Hybrid Demon Algorithm for the Two-Dimensional Orthogonal Strip Packing Problem

This paper develops a hybrid demon algorithm for a two-dimensional orthogonal strip packing problem. This algorithm combines a placement procedure based on an improved heuristic, local search, and demon algorithm involved in setting one parameter. The hybrid algorithm is tested on a wide set of benchmark instances taken from the literature and compared with other well-known algorithms. The computation results validate the quality of the solutions and the effectiveness of the proposed algorithm

The Keck Baryonic Structure Survey: using foreground/background galaxy pairs to trace the structure and kinematics of circumgalactic neutral hydrogen at z ∼ 2

We present new measurements of the spatial distribution and kinematics of neutral hydrogen in the circumgalactic and intergalactic medium surrounding star-forming galaxies at z ∼ 2. Using the spectra of ≃3000 galaxies with redshifts 〈z〉 = 2.3 ± 0.4 from the Keck Baryonic Structure Survey, we assemble a sample of more than 200 000 distinct foreground-background pairs with projected angular separations of 3–500 arcsec and spectroscopic redshifts, with 〈z_(fg)〉 = 2.23 and 〈zbg〉 = 2.57 (foreground, background redshifts, respectively.) The ensemble of sightlines and foreground galaxies is used to construct a 2D map of the mean excess HI Lyα optical depth relative to the intergalactic mean as a function of projected galactocentric distance (20 ≲ D_(tran)/pkpc ≲ 4000) and line-of-sight velocity. We obtain accurate galaxy systemic redshifts, providing significant information on the line-of-sight kinematics of HI gas as a function of projected distance D_(tran). We compare the map with cosmological zoom-in simulation, finding qualitative agreement between them. A simple two-component (accretion, outflow) analytical model generally reproduces the observed line-of-sight kinematics and projected spatial distribution of HI. The best-fitting model suggests that galaxy-scale outflows with initial velocity v_(out) ≃ 600 km s⁻¹ dominate the kinematics of circumgalactic HI out to D_(tran) ≃ 50 kpc, while HI at D_(tran) ≳ 100 kpc is dominated by infall with characteristic v_(in) ≲ circular velocity. Over the impact parameter range 80 ≲ D_(tran)/pkpc ≲ 200, the HI line-of-sight velocity range reaches a minimum, with a corresponding flattening in the rest-frame Lyα equivalent width. These observations can be naturally explained as the transition between outflow-dominated and accretion-dominated flows. Beyond D_(tran) ≃ 300 pkpc (∼1 cMpc), the line-of-sight kinematics are dominated by Hubble expansion

The Keck Baryonic Structure Survey: Using foreground/background galaxy pairs to trace the structure and kinematics of circumgalactic neutral hydrogen at z∼2z \sim 2

We present new measurements of the spatial distribution and kinematics of neutral hydrogen in the circumgalactic and intergalactic medium surrounding star-forming galaxies at z ~ 2. Using the spectra of ~ 3000 galaxies with redshifts +/- 0.4 from the Keck Baryonic Structure Survey (KBSS), we assemble a sample of more than 200,000 distinct foreground-background pairs with projected angular separations of 3 - 500 arcsec and spectroscopic redshifts, with = 2.23 and = 2.57. The ensemble of sightlines and foreground galaxies is used to construct a 2D map of the mean excess Ly$\alpha$ optical depth relative to the intergalactic mean as a function of projected galactocentric distance (20 < $D_{tran}$/pkpc < 4000) and line-of-sight velocity. We provide information on the line-of-sight kinematics of H I gas as a function of projected distance $D_{tran}$. We compare the map with cosmological zoom-in simulation, finding qualitative agreement between them. A simple two-component (accretion, outflow) analytical model generally reproduces the observed line-of-sight kinematics and projected spatial distribution of H I. The best-fitting model suggests that galaxy-scale outflows with initial velocity $v_{out}$ ~ 600 km/s dominate the kinematics of circumgalactic H I out to $D_{tran}$ ~ 50 kpc, while H I at $D_{tran}$ > 100 kpc is dominated by infall with characteristic $v_{in}$ < $v_c$, where $v_c$ is the circular velocity of the host halo ($M_h$ ~ $10^{12} M_\odot$). Over the impact parameter range 80 < $D_{tran}$/pkpc < 200, the H I line-of-sight velocity range reaches a minimum, with a corresponding flattening in the rest-frame Ly$\alpha$ equivalent width. These observations can be naturally explained as the transition between outflow-dominated and accretion-dominated flows. Beyond $D_{tran}$ ~ 300 kpc, the line of sight kinematics are dominated by Hubble expansion.Comment: 27 pages, 24 figures, 3 tables, accepted by MNRAS. Additional data at http://ramekin.caltech.edu/KBSS

An Enhanced Differential Evolution Based Algorithm with Simulated Annealing for Solving Multiobjective Optimization Problems

National Science Foundation of China [60672018, 40774065]An enhanced differential evolution based algorithm, named multi-objective differential evolution with simulated annealing algorithm (MODESA), is presented for solving multiobjective optimization problems (MOPs). The proposed algorithm utilizes the advantage of simulated annealing for guiding the algorithm to explore more regions of the search space for a better convergence to the true Pareto-optimal front. In the proposed simulated annealing approach, a new acceptance probability computation function based on domination is proposed and some potential solutions are assigned a life cycle to have a priority to be selected entering the next generation. Moreover, it incorporates an efficient diversity maintenance approach, which is used to prune the obtained nondominated solutions for a good distributed Pareto front. The feasibility of the proposed algorithm is investigated on a set of five biobjective and two triobjective optimization problems and the results are compared with three other algorithms. The experimental results illustrate the effectiveness of the proposed algorithm

Characterization of catalysts with techniques of XRD, TG, etc.

The crystal structure of a certain sample was evaluated by powder X-ray diffraction (XRD, D8 Advance, Germany) using Cu Kα radiation (λ= 0.15418 nm) at 40 kV, 30 mA, with a scan step of 0.02° and a 2θ ranging from 5 to 75 °. The 77K-N2 adsorption-desorption isotherm of a certain sample was measured by using a Micromeritcs ASAP2010 instrument. Then the specific surface area and pore-size distribution of this catalyst was calculated using the Brunauer–Emmett–Teller (BET) method for the adsorption branch and the Barret–Joyner–Halenda (BJH) method for a desorption branch, respectively. The thermogravimetric (TG) analysis of a certain catalyst was carried out in an air flow of 50 ml/min by using a HCT-1 thermal analytical instrument. The sample weight was ~10 mg and the typical heating rate was 10 K/min

Data from: UiO-66 supported Fe catalyst: a vapor deposition preparation method and its superior catalytic performance for removal of organic pollutants in water

A vapor deposition (VD) method was established for preparation of UiO-66 supported Fe (Fe/UiO-66) catalyst, which provided the first case of metal-organic framework (MOF) -supported Fe catalyst prepared by using vapor-based method. The Fe loading was around 7.0 ~8.5 wt% under present preparation conditions. The crystal structure of UiO-66 was not obviously influenced by the Fe loading, while the surface area significantly decreased, implicating most of the Fe components resided within the pores on UiO-66. The results for the methyl orange (MO) removal tests showed that MO in aqueous solution can be removed by UiO-66 by adsorption, and in contrast, it can be oxidized by H2O2 with the catalysis of Fe/UiO-66. Further catalytic tests showed that Fe/UiO-66 was rather effective to catalyze the oxidation of benzene derivatives like aniline in water in terms of chemical oxygen demand (COD) removal efficiency. The catalytic tests results for Fe/UiO-66 were compared to that of Fe/Al2O3 with a same Fe loading, as well as compared to the catalysts reported in the literature. This paper provides a general strategy for VD preparation of MOF-supported Fe catalyst on one hand, and new catalysts for removing organic pollutants from water on the other hand

Conformal Imidazolium 1D Perovskite Capping Layer Stabilized 3D Perovskite Films for Efficient Solar Modules

Abstract Although the perovskite solar cells have been developed rapidly, the industrialization of perovskite photovoltaics is still facing challenges, especially considering their stability issues. Here, the new type of benzimidazolium salt, N,N′‐dialkylbenzimidazolium iodide, is proposed and functionalized to convert the three‐dimensional (3D) FACs‐perovskite films into one‐dimensional (1D) capping layer topped 1D/3D structure either in individual device or module levels. This conformal interface modulation demonstrates that not only can effectively stabilize FACs‐based perovskite films by inhibiting the lateral and vertical iodide diffusions in devices or modules, ensuring an excellent operation and environmental stability, but also provides an excellent charge transporting channel through the well‐designed 1D crystal structure. Consequently, efficient device performance with power conversion efficiency up to 24.3% is readily achieved. And the large‐area perovskite solar modules with high efficiency (19.6% for the active areas of 18 cm2) and long‐term stability (about 500 h in AM 1.5G illumination or about 1000 h under double‐85 conditions) are also successfully verified