Les P. Pook 《Fatigue & Fracture of Engineering Materials & Structures》2019,42(9):1889-1911

Following the discovery of oil and gas, fixed welded tubular steel platforms were first installed in the North Sea in 1966. They are subjected to significant fatigue loads due to wave action. A report on proposed standard load histories was published in 1976. These were based on theoretical calculations. In 1979, increasing interest led to the formation of the Wave Action Standards History (WASH) Working Group. Strain gauge data for platforms in the North Sea were made available to the Working Group so later standard load histories were based on service data rather than theoretical calculations. Mathematical techniques used are reviewed, and some load histories are described as case studies. A framework was developed that could be used to formulate a particular standard load history but left open the option of incorporating alternative features, with relatively little additional work.  相似文献   

    

Kyriakos G. Vamvoudakis  Farshad R. Pour Safaei  Joo P. Hespanha 《国际强度与非线性控制杂志
》2019,29(11):3502-3517

We consider the output feedback event‐triggered control of an off‐grid voltage source inverter (VSI) with unknown inductance‐capacitance (L ? C) filter dynamics and connected load in the presence of an input disturbance acting at the inverter. Due to uncertain dynamics and unmodeled parameters in the L ? C filter connected to the VSI, we use an adaptive observer to reconstruct the system's states by measuring only the voltage at the output. The control mechanism is constructed based on an impulsive actor/critic framework that approximates the cost, the event‐triggered controller, and the worst case disturbance and generates the desired AC output with the least energy dissipation. We provide rigorous stability proofs and illustrate the applicability of our results through a simulation example.  相似文献   

    

《Applied Soft Computing》2019

This paper proposes a robust optimization approach for multiple damage identification of plate-like structures. Different from traditional particle swarm optimizations (PSOs), a combined PSO and niche technique (NPSO) is proposed to solve multimodal optimization problems, with the full consideration of subswarm creation, merging and absorbing mechanism. As a hypersensitive parameter to damage, the curvature mode shape is adopted to construct the objective function. Case studies are conducted to investigate the effectiveness and robustness of the algorithm on multi-damage identification. Simulation results show that the proposed algorithm exhibits robust search performance on identifying damage locations accurately with good convergence behavior. It is hoped that this study can provide guidance on robust damage detection, especially when the structure is subject to multiple damages and external disturbances.  相似文献   

    

Soroush Kamrava  Ranajay Ghosh  Zhihao Wang  Ashkan Vaziri 《Advanced Engineering Materials》2019,21(2)

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Primo Koelj  Stanislav Vrtnik  Andreja Jelen  Mitja Krnel  Darja Ga nik  Goran Drai&#x;  Anton Meden  Magdalena Wencka  David Jezer&#x;ek  Janez Leskovec  Suomyadipta Maiti  Walter Steurer  Janez Dolin&#x;ek 《Advanced Engineering Materials》2019,21(5)

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Muhammad Iqbal  Yusuf Valentino Kaneti  Jeonghun Kim  Brian Yuliarto  Yong‐Mook Kang  Yoshio Bando  Yoshiyuki Sugahara  Yusuke Yamauchi 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(6)

Palladium (Pd) plays an important role in numerous catalytic reactions, such as methanol and ethanol oxidation, oxygen reduction, hydrogenation, coupling reactions, and carbon monoxide oxidation. Creating Pd‐based nanoarchitectures with increased active surface sites, higher density of low‐coordinated atoms, and maximized surface coverage for the reactants is important. To address the limitations of pure Pd, various Pd‐based nanoarchitectures, including alloys, intermetallics, and supported Pd nanomaterials, have been fabricated by combining Pd with other elements with similar or higher catalytic activity for many catalytic reactions. Herein, recent advances in the preparation of Pd‐based nanoarchitectures through solution‐phase chemical reduction and electrochemical deposition methods are summarized. Finally, the trend and future outlook in the development of Pd nanocatalysts toward practical catalytic applications are discussed.  相似文献   

    

Guofen Song  Jinghan Li  Yang Yuan  Lulu Yao  Jiajun Gu  Qinglei Liu  Wang Zhang  Yishi Su  Di Zhang 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(18)

Assembling nanosized building blocks into macroscopic 3D complex structures is challenging. Here, nanosized metal and semiconductor building blocks with a variety of sizes and shapes (spheres, stars, and rods) are successfully assembled into a broad range of hierarchical (nanometer to micrometer) assemblies of functional materials in centimeter size using butterfly wings as templates. This is achieved by the introduction of steric hindrance to the assembly process, which compensates for attraction from the environmentally sensitive hydrogen bonds and prevents the aggregation of nanosized building blocks. Of these materials, Au nanostar assemblies show a superior enhancement in surface‐enhanced Raman scattering (SERS) performance (rhodamine 6G, 1506 cm^?1) under 532, 633, and 780 nm excitation—this is 3.1–4.4, 3.6–3.9, and 2.9–47.3 folds surpassing Au nanosphere assemblies and commercial SERS substrates (Q‐SERS), respectively. This method provides a versatile route for the assembly of various nanosized building blocks into different 3D superstructures and for the construction of hybrid nanomaterials and nanocomposites.  相似文献   

    

Goli Nagaraju  S. Chandra Sekhar  Bhimanaboina Ramulu  Jae Su Yu 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(16)

Self‐powered charging systems in conjunction with renewable energy conversion and storage devices have attracted promising attention in recent years. In this work, a prolific approach to design a wind/solar‐powered rechargeable high‐energy density pouch‐type hybrid supercapacitor (HSC) is proposed. The pouch‐type HSC is fabricated by engineering nature‐inspired nanosliver (nano‐Ag) decorated Ni_0.67Co_0.33S forest‐like nanostructures on Ni foam (nano‐Ag@NCS FNs/Ni foam) as a battery‐type electrode and porous activated carbon as a capacitive‐type electrode. Initially, the core–shell‐like NCS FNs/Ni foam is prepared via a single‐step wet‐chemical method, followed by a light‐induced growth of nano‐Ag onto it for enhancing the conductivity of the composite. Utilizing the synergistic effects of forest‐like nano‐Ag@NCS FNs/Ni foam as a composite electrode, the fabricated device shows a maximum capacitance of 1104.14 mF cm^?2 at a current density of 5 mA cm^?2 and it stores superior energy and power densities of 0.36 mWh cm^?2 and 27.22 mW cm^?2, respectively along with good cycling stability, which are higher than most of previous reports. The high‐energy storage capability of HSCs is further connected to wind fans and solar cells to harvest renewable energy. The wind/solar charged HSCs can effectively operate various electronic devices for a long time, enlightening its potency for the development of sustainable energy systems.  相似文献   

    

Xiaojiang Liu  Hongcheng Gu  Haibo Ding  Xin Du  Zhenzhu He  Liangdong Sun  Junlong Liao  Pengfeng Xiao  Zhongze Gu 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(35)

Surfaces combining antispreading and high adhesion can find wide applications in the manipulation of liquid droplets, generation of micropatterns and liquid enrichment. To fabricate such surfaces, almost all the traditional methods demand multi‐step processes and chemical modification. And even so, most of them cannot be applied for some liquids with extremely low surface energy. In the past decade, multiply re‐entrant structures have aroused much attention because of their universal and modification‐independent antiadhesion or antipenetration ability. Unfortunately, theories and applications about their liquid adhesion behavior are still rare. In this work, inspired by the springtail skin and gecko feet in the adhered state, it is demonstrated that programmable liquid adhesion is realized on the 3D‐printed micro doubly re‐entrant arrays. By arranging the arrays reasonably, three different Cassie adhesion behaviors can be obtained: I) no residue adhesion, II) tunable adhesion, and III) absolute adhesion. Furthermore, various arrays are designed to tune macro/micro liquid droplet manipulation, which can find applications in the transportation of liquid droplets, liquid enrichment, generation of tiny droplets, and micropatterns.  相似文献   

    

Xin Deng  Lanlan Yang  Hanlin Huang  Yuying Yang  Shiqiang Feng  Min Zeng  Qi Li  Dongsheng Xu 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(35)

In recent years, metal–organic frameworks (MOFs) have received extensive interest because of the diversity of their composition, structure, and function. To promote the MOFs' function and performance, the construction of hollow structural metal–organic frameworks and nanoparticle–MOF composites is significantly effective but remains a considerable challenge. In this article, a transformation strategy is developed to synthesize hollow structural Co‐MOF‐74 by solvothermal transformation of ZIF‐67. These Co‐MOF‐74 particles exhibit a double‐layer hollow shell structure without remarkable shape change compared to original ZIF‐67 particles. The formation of hollow structure stemmed from the density difference of Co between ZIF‐67 and Co‐MOF‐74. By this strategy, hollow structural Co‐MOF‐74 with different sizes and shapes are obtained from corresponding ZIF‐67, and metal nanoparticles@Co‐MOF‐74 is synthesized by corresponding nanoparticles@Co‐ZIF‐67. To verify the structural advantages of hollow structural Co‐MOF‐74 and Ag nanoparticles@Co‐MOF‐74, photocatalytic CO₂ reduction is used as a model reaction. Conventionally synthesized Co‐MOF‐74 (MOF‐74‐C), hollow structural Co‐MOF‐74 synthesized by transformation method (MOF‐74‐T) and Ag nanoparticles@Co‐MOF‐74 (AgNPs@MOF‐74) are used as cocatalysts in this reaction. As a result, the cocatalytic activity of MOF‐74‐T and AgNPs@MOF‐74 is 1.8 times and 3.8 times that of MOF‐74‐C, respectively.  相似文献