Non-linear dynamic analysis of reinforced concrete bridge columns under vehicle impact loadings

A 3D nonlinear impact analysis was performed for reinforced concrete bridge columns under truck impact loadings. Three different boundary conditions were considered to investigate the effect of superstructures on the integral column during impact. Fixed bottom conditions and restraints in the loading direction at the top of the column (Model I) showed the largest damaged area. The dominant failure mode of the column was shear. However, Model II, which is equivalent to Model I with the top released, showed less damage, and the dominant failure modes were flexure rather than shear. In Model III, in which the effect of featured the superstructure was considered, the shear and flexural damage to the column were reduced due to the movement of the superstructures

A Crystal-Less Programmable Clock Generator With RC-LC Hybrid Oscillator for GHz Applications in 14 nm FinFET CMOS

This paper presents a crystal-less programmable clock generator. The programmable clock generator takes advantages of both RC and LC oscillators. The frequency reference is generated by the RC oscillator without using expensive external crystals. The sawtooth signal generated from the RC oscillator is sampled by low phase-noise differential clocks which are divided from the LC oscillator. The timing information is then amplified by the sampler which uses hysteresis. An additional block, gain adjuster (GA), reduces lock time and dithering. After the system gets locked, it achieves 0.01 %/V and 25.5 ppm/degrees C frequency variations for 100 MHz generated clock. The 14 nm FinFET CMOS programmable clock generator draws 28 mA current from a single 1.8 V supply and occupies an active area of 0.12 mm(2)(.) It achieves 163 dBc/Hz FoM for 100 MHz test clock.N

Metal-Organic Frameworks with Metal Catecholates for O2/N2 Separation

Oxygen and nitrogen are widely produced feedstocks with diverse fields of applications, but are primarily obtained via the energy-intensive cryogenic distillation of air. More energy-efficient processes are desirable, and materials such as zeolites and metal-organic frameworks (MOFs) have been studied for air separation. Inspired by recent theoretical work identifying metal-catecholates for enhancement of O2 selectivity MOFs, in this work the computation-ready experimental (CoRE) database of MOF structures was screened to identify promising candidates for incorporation of metal catecholates. Based on structural requirements, preliminary Grand-Canonical Monte Carlo simulations, and further constraints to ensure the computational feasibility, over 5,000 structures were eliminated and four MOFs (UiO-66(Zr), Ce-UiO-66, MOF-5, and IRMOF-14) were treated with periodic density functional theory (DFT). Metal catecholates (Mg, Co, Ni, Zn, and Cd) were selected based on cluster DFT calculations and were added to the shortlisted MOFs. Periodic DFT was used to compute O2 and N2 binding energies near metal catecholates. We find that the binding energies are primarily dependent on the metals in the metal catecholates, all of which bind O2 quite strongly (80-258 kJ/mol) and have weaker binding for N2 (3-148 kJ/mol). Of those studied here, Cd-catecholated MOFs are identified as the most promisin

The JCMT Transient Survey : Single Epoch Transients and Variability of Faint Sources

© 2022. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/Short-duration flares at millimeter wavelengths provide unique insights into the strongest magnetic reconnection events in stellar coronae, and combine with longer-term variability to introduce complications to next-generation cosmology surveys. We analyze 5.5 years of JCMT Transient Survey 850 micron submillimeter monitoring observations toward eight Gould Belt star-forming regions to search for evidence of transient events or long-duration variability from faint sources. The eight regions (30 arcmin diameter fields), including ~1200 infrared-selected YSOs, have been observed on average 47 times with integrations of approximately half an hour, or one day total spread over 5.5 years. Within this large data set, only two robust faint source detections are recovered: JW 566 in OMC 2/3 and MGM12 2864 in NGC 2023. JW 566, a Class II TTauri binary system previously identified as an extraordinary submillimeter flare, remains unique, the only clear single-epoch transient detection in this sample with a flare eight times bright than our ~4.5 sigma detection threshold of 55 mJy/beam. The lack of additional recovered flares intermediate between JW 566 and our detection limit is puzzling, if smaller events are more common than larger events. In contrast, the other submillimeter variable identified in our analysis, Source 2864, is highly variable on all observed timescales. Although Source 2864 is occasionally classified as a YSO, the source is most likely a blazar. The degree of variability across the electromagnetic spectrum may be used to aid source classification.Peer reviewe

Direct 2D-to-3D transformation of pen drawings

Pen drawing is a method that allows simple, inexpensive, and intuitive two-dimensional (2D) fabrication. To integrate such advantages of pen drawing in fabricating 3D objects, we developed a 3D fabrication technology that can directly transform pen-drawn 2D precursors into 3D geometries. 2D-to-3D transformation of pen drawings is facilitated by surface tension-driven capillary peeling and floating of dried ink film when the drawing is dipped into an aqueous monomer solution. Selective control of the floating and anchoring parts of a 2D precursor allowed the 2D drawing to transform into the designed 3D structure. The transformed 3D geometry can then be fixed by structural reinforcement using surface-initiated polymerization. By transforming simple pen-drawn 2D structures into complex 3D structures, our approach enables freestyle rapid prototyping via pen drawing, as well as mass production of 3D objects via roll-to-roll processing

Active Learning Configuration Interaction for Excited States Calculations of Polycyclic Aromatic Hydrocarbons

We present the active learning configuration interaction (ALCI) method for multiconfigurational calculations based on large active spaces. ALCI leverages the use of an active learning procedure to find important electronic configurations among the full configuration space generated within an active space. We tested it for the calculation of singlet-singlet excited states of acenes and pyrene, by using different machine learning algorithms. The ALCI method yields excitation energies within 0.2–0.3 eV from those obtained by traditional complete active space configuration interaction (CASCI) calculations (affordable for active spaces up to 16 electrons in 16 orbitals), by including only a small fraction of the CASCI configuration space in the calculations. For larger active spaces (up to 26 electrons in 26 orbitals), not affordable with traditional CI methods, ALCI captures the trends of experimental excitation energies. Overall ALCI provides satisfactory approximations to large active-space wave functions with up to ten orders of magnitude fewer configurations. These ALCI wave functions are promising and affordable starting points for subsequent second order perturbation theory or pair-density functional theory calculations

Understanding the Mechanisms of CO₂ Adsorption Enhancement in Pure Silica Zeolites under Humid Conditions

Using grand canonical Monte Carlo simulations, computational screening of hundreds of pure silica zeolites were conducted to identify materials that show enhanced CO₂ uptake under humid conditions. Herein, we show that CO₂ adsorption performance can be either enhanced or degraded depending on the CO₂/H₂O binding site separations and characteristics of CO₂–H₂O interaction energies. As expected, CO₂ adsorption capacity is significantly degraded when its binding sites overlap with the H₂O sites. On the other hand, CO₂ adsorption performance is enhanced when CO₂/H₂O binding sites are clearly separated as shown from the molecular simulations. However, we show that there are zeolite structures where CO₂ enhancement is observed despite the close distance between the CO₂ and H₂O binding sites. It is demonstrated that favorable long-range Coulomb interaction between CO₂ and H₂O molecules is responsible for enhanced CO₂ adsorption performance in these materials

Fatigue Behavior of Concrete Beams Prestressed with Partially Bonded CFRP Bars Subjected to Cyclic Loads

The lack of ductility is the greatest concern in the applications of carbon fiber reinforced polymer (CFRP) materials, when used as pre-stressing reinforcements. To improve the ductility, a partially bonded FRP system which is intentionally unbonded in the middle part of the beam and bonded in both end parts of the beam has been developed and applied to prestressed concrete beams. While, many researchers investigated the instantaneous performance of partially bonded CFRP prestressed concrete beams, this study intended to evaluate the fatigue performance, the static load-carrying capacity after fatigue loading and ductility. Based on the fatigue loading tests followed by static loading tests, over-reinforced and web-confined partially bonded CFRP prestressed concrete beams exhibited satisfactory fatigue performance without cracks and stiffness degradation during fatigue loading. In addition, no degradation of load-carrying capacity was observed in static loading tests after the fatigue tests. The ductility index of concrete beams, prestressed with partially bonded CFRP bars, is combined with over-reinforcements and web-confinements, similar to that of beams prestressed with steel bars

Korean Business Groups and Performance of Group-Affiliated Professional Sport Teams: Focusing on the Asian Financial Crisis

This study examines the impact of Korean business groups, chaebols, on the sporting performance of their affiliated professional sports teams using game data from 1983 to 2013. We investigated whether or not chaebol ownership of professional sports teams is more efficient than non-chaebol ownership in achieving athletic success on the field of play. Our empirical evidence found that the chaebol-affiliated teams are more likely to be the league winners or finalists than non-chaebol teams are. We also tested the relationship between the financial crisis in the wider economy that deflates firm resources and athletic outcomes in the affiliated teams. In the tests, which divide the sample period into three 10-year periods, the results of two sub-samples (1983–1993 and 2004–2013) were in line with previous results. We, however, identified an exception when chaebol teams did not play in more final matches of a league between 1994 and 2003, the time interval that includes the period of drastic restructuring of business groups during the 1997 Asian financial crisis