Failure mechanism of single-layer saddle-curve reticulated shells subjected to erathquakes

p. 345-354In order to have a good understanding of the failure mechanism of single-layer saddle-curve reticulated shells under earthquake motion, dynamic failure mode of single-layer saddlecurve reticulated shells under earthquake motion is discussed with accumulation of material damage introduced to analyze the failure of these shells under dynamic actions. Based on the comprehension of the mechanical behaviours and structural full-range characteristic responses in an example, dynamic strength failure due to excessive development of plastic deformation is a mainly failure mode for single-layer saddle-curve reticulated shells subjected to earthquakes. Then, a method is proposed for determination of failure state. The relationships between structural responses under ultimate load and different structural parameters are investigated through simulation.Zhi, X.; Fan, F.; Shen, S.; Fan, Q. (2009). Failure mechanism of single-layer saddle-curve reticulated shells subjected to erathquakes. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/652

Tunable Syngas Production from CO2 and H2O in an Aqueous Photoelectrochemical Cell

Syngas, the mixture of CO and H2, is a key feedstock to produce methanol and liquid fuels in industry, yet limited success has been made to develop clean syngas production using renewable solar energy. We demonstrated that syngas with a benchmark turnover number of 1330 and a desirable CO/H2 ratio of 1:2 could be attained from photoelectrochemical CO2 and H2O reduction in an aqueous medium by exploiting the synergistic co‐catalytic effect between Cu and ZnO. The CO/H2 ratio in the syngas products was tuned in a large range between 2:1 and 1:4 with a total unity Faradaic efficiency. Moreover, a high Faradaic efficiency of 70 % for CO was acheived at underpotential of 180 mV, which is the lowest potential ever reported in an aqueous photoelectrochemical cell. It was found that the combination of Cu and ZnO offered complementary chemical properties that lead to special reaction channels not seen in Cu, or ZnO alone.Mixture is better: Syngas (CO+H2) with tunable composition is synthesized from the reduction of CO2 and H2O in an aqueous photoelectrochemcal cell. A turnover number of 1330 and a high Faradaic efficiency of 70 % for CO at underpotential of 180 mV are acheived. The excellent perfomance is attributed to the coupling effects of strong light harvesting of p‐n Si, efficient electron extraction of GaN nanowires, and fast surface reaction kinetics of Cu–ZnO co‐catalysts.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134441/1/anie201606424_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134441/2/anie201606424.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134441/3/anie201606424-sup-0001-misc_information.pd

Multi-band filters on microstrip line

58 p.This study is mainly based on the knowledge of microstrip line, filters and simulation software ADS. The main objective of this project is to design and simulate multi-band filters using Step Impedance Resonator (SIR) and Parallel Coupled Microstrip Line (PCML). The SIR is made of three sections with different impedance between the middle and the two sides, and the PCML is placed at the two sides to control the bandwidth of the multi-band filter. The SIR section and the PCML were extensively studied, and a dual-band filter has been investigated. By following the designed method of the previous study and properly adjusting the dimensions, a compact tri-band filter was designed with good response in all passband and stop band.​Master of Science (Communications Engineering

Modeling of the Snowdrift in Cold Regions: Introduction and Evaluation of a New Approach

Unbalanced, or non-uniform, snow loads caused by snow drifting or sliding in cold regions with heavy snowfalls, can be a serious problem for the building industry. However, the methods for predicting snow distribution still need to be improved. Field observation is the most direct and reliable method to study snow distribution, but because the natural environment is uncontrollable and varies dramatically, sometimes conclusions may be confused under the influence of the many variables in the investigation. This paper proposes a snowing experiment approach using an outdoor snow–wind combined experiment facility for the study of snow distribution. The facility can produce a stable and controllable wind field and snowfall environment. Experiments which focused on snowdrift around a building were conducted during the winter to make an evaluation of the repeatability and reliability of the new approach. Finally, from the analysis of results, it was demonstrated that the experimental facility was stable and that the similarity criterion adopted for the snowing pattern was reliable. Especially, the minimum value of the friction speed ratio was suggested to ensure the test accuracy

A hydraulic model for flow rate ratio of triple cannulation extracorporeal membrane oxygenation

Triple cannulation extracorporeal membrane oxygenation (ECMO) provides advanced life support to patients with respiratory and hemodynamic failure by replacing the function of the heart and lungs. The application of triple cannulation ECMO suffers from the difficulty in predicting the flow rate ratios of the cannulas. We address this difficulty by proposing a hydraulic model, where the effects of the triple cannulation are modeled by head losses in a bifurcated tube. The proposed model correctly predicts the flow rate ratios and quantitatively captures the effects of geometrical parameters. This model can help to configure the cannula pair for clinical practices and interventional therapy.& nbsp;Published under an exclusive license by AIP Publishing

Failure modes for reticulated domes under diverse impact

p. 1813-1822FE models of both the single-layer Kiewitt-8 reticulated domes with a span of 60m and the cylindrical impactor were developed incorporating ANSYS/LS-DYNA. Afterward, fourteen groups impact are simulated by changing the impact position or impacted angle on reticulated dome, and impact velocity and mass of impactor are changed for each group impact. On the basis of large numbers of numerical simulations, characteristics of dynamic response for reticulated dome under impact are shown. And four failure modes (Members slightly damaged, Local collapse of dome, Global collapse of dome, Members shear failed) are presented for single-layer Kiewitt-8 reticulated dome under diverse impact. The distributing of failure modes for the fourteen types impact are different from each other, and the adverse position and angle are summrized.Fan, F.; Wang, D.; Zhi, X.; Tan, S.; Shen, S. (2009). Failure modes for reticulated domes under diverse impact. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/681

Wafer-Level Artificial Photosynthesis for CO₂ Reduction into CH₄ and CO Using GaN Nanowires

We report on the first demonstration of high-conversion-rate photochemical reduction of carbon dioxide (CO₂) on gallium nitride (GaN) nanowire arrays into methane (CH₄) and carbon monoxide (CO). It was observed that the reduction of CO₂ to CO dominates on as-grown GaN nanowires under ultraviolet light irradiation. However, the production of CH₄ is significantly increased by using the Rh/Cr₂O₃ core/shell cocatalyst, with an average rate of ∼3.5 μmol g_cat^–1 h^–1 in 24 h. In this process, the rate of CO₂ to CO conversion is suppressed by nearly an order of magnitude. The rate of photoreduction of CO₂ to CH₄ can be further enhanced and can reach ∼14.8 μmol g_cat^–1 h^–1 by promoting Pt nanoparticles on the lateral <i>m</i>-plane surfaces of GaN nanowires, which is nearly an order of magnitude higher than that measured on as-grown GaN nanowire arrays. This work establishes the potential use of metal-nitride nanowire arrays as a highly efficient photocatalyst for the direct photoreduction of CO₂ into chemical fuels. It also reveals the potential of engineered core/shell cocatalysts in improving the selectivity toward more valuable fuels

Photoinduced Conversion of Methane into Benzene over GaN Nanowires

As a class of key building blocks in the chemical industry, aromatic compounds are mainly derived from the catalytic reforming of petroleum-based long chain hydrocarbons. The dehydroaromatization of methane can also be achieved by using zeolitic catalysts under relatively high temperature. Herein we demonstrate that Si-doped GaN nanowires (NWs) with a 97% rationally constructed <i>m</i>-plane can directly convert methane into benzene and molecular hydrogen under ultraviolet (UV) illumination at rt. Mechanistic studies suggest that the exposed <i>m</i>-plane of GaN exhibited particularly high activity toward methane C–H bond activation and the quantum efficiency increased linearly as a function of light intensity. The incorporation of a Si-donor or Mg-acceptor dopants into GaN also has a large influence on the photocatalytic performance

Photoelectrochemical reduction of carbon dioxide using Ge doped GaN nanowire photoanodes

We report on the direct conversion of carbon dioxide (CO₂) in a photoelectrochemical cell consisting of germanium doped gallium nitride nanowire anode and copper (Cu) cathode. Various products including methane (CH₄), carbon monoxide (CO), and formic acid (HCOOH) were observed under light illumination. A Faradaic efficiency of ∼10% was measured for HCOOH. Furthermore, this photoelectrochemical system showed enhanced stability for 6 h CO₂ reduction reaction on low cost, large area Si substrates