QUANTIFICATION OF STRUCTURAL PROBABILITY OF FAILURE DUE TO EXTREME EVENTS

ABSTRACT: This paper tries to probe the composition of probability of failure (POF) in reliability-based structural design. The focus is on extreme event (EE) related risk of structural failure. Extreme events that may cause structural failure are often described by a severity-based threshold which can be a hazard intensity measure or return period. Such definition of EE is not directly connected to the POF. In order to quantify its portion of risk in the overall POF, a different definition is formulated. It is shown that this new definition of EE delineates a subset of failure events which not only coincides with the severity-based definition in terms of probability value but also represents the tail properties of the demand and capacity distribution models. Examples are given to illustrate the use of this approach to evaluate EE in hazard load comparison for structural design. It is hoped that this effort will help to put some EE related structural design issues (e.g. uncertainty of hazard loading, different demand and capacity models, the influence of tail property of probabilistic distribution models, extreme event limit states, and load combinations etc.) in proper perspective.

Investigation of the Performance of Donor–Acceptor Conjugated Polymers in Electrolyte‐Gated Organic Field‐Effect Transistors

From Wiley via Jisc Publications RouterHistory: received 2021-01-21, rev-recd 2021-04-23, pub-electronic 2021-06-24Article version: VoRPublication status: PublishedFunder: Cambridge Display Technology (“CDT”) Limited; Grant(s): 2672530Funder: Engineering and Physical Sciences Research Council; Id: http://dx.doi.org/10.13039/501100000266; Grant(s): EP/K03099X/1Abstract: Electrolyte‐gated organic field‐effect transistors (EGOFETs) are gaining interest for application in bioelectronic devices. However, robust performance in terms of charge‐carrier mobility, on‐to‐off drain current ratio (Ion/Ioff), and turn‐on speed are required for real application. Here, donor‐acceptor (D‐A) conjugated polymers, namely poly[2,5‐(2‐octyldodecyl)‐3,6‐diketopyrrolopyrrole‐alt‐5,5‐(2,5‐di(thien‐2‐yl)thieno[3,2‐b]thiophene)] (PDPPDTT) and indacenodithiophene‐co‐benzothiadiazole (PIDTBT), are evaluated in EGOFETs. The operational performance of these materials is compared to that of the well‐established conjugated polymer, poly[2,5‐bis(3‐hexadecylthiophen‐2‐yl)thieno[3,2‐b]thiophene] (PBTTT). The effective mobility extracted for the PDPPDTT (0.18 cm2 V−1 s−1), and PIDTBT (0.16 cm2 V−1 s−1) devices is almost double that of the PBTTT (0.10 cm2 V−1 s−1) based device and the Ion/Ioff is one ((PDPPDTT): 3 × 103) or two ((PIDTBT): 2 × 104) orders of magnitude higher than that of PBTTT (2 × 102) devices. The extracted values compare favorably to those of the highest performing EGOFETs and EGOFETs based on the D‐A polymers turn from off to on state two to ten times faster than the analogous PBTTT device with an improved subthreshold swing. These results show that D‐A polymers with a planar conjugated backbone enable the development of robust EGOFETs that are well appropriate for applications in bioelectronic devices

Implications for Cation Selectivity and Evolution by a Novel Cation Diffusion Facilitator Family Member From the Moderate Halophile Planococcus dechangensis

In the cation diffusion facilitator (CDF) family, the transported substrates are confined to divalent metal ions, such as Zn2+, Fe2+, and Mn2+. However, this study identifies a novel CDF member designated MceT from the moderate halophile Planococcus dechangensis. MceT functions as a Na+(Li+, K+)/H+ antiporter, together with its capability of facilitated Zn2+ diffusion into cells, which have not been reported in any identified CDF transporters as yet. MceT is proposed to represent a novel CDF group, Na-CDF, which shares significantly distant phylogenetic relationship with three known CDF groups including Mn-CDF, Fe/Zn-CDF, and Zn-CDF. Variation of key function-related residues to “Y44-S48-Q150” in two structural motifs explains a significant discrimination in cation selectivity between Na-CDF group and three major known CDF groups. Functional analysis via site-directed mutagenesis confirms that MceT employs Q150, S158, and D184 for the function of MceT as a Na+(Li+, K+)/H+ antiporter, and retains D41, D154, and D184 for its facilitated Zn2+ diffusion into cells. These presented findings imply that MceT has evolved from its native CDF family function to a Na+/H+ antiporter in an evolutionary strategy of the substitution of key conserved residues to “Q150-S158-D184” motif. More importantly, the discovery of MceT contributes to a typical transporter model of CDF family with the unique structural motifs, which will be utilized to explore the cation-selective mechanisms of secondary transporters

2021 roadmap for sodium-ion batteries

Abstract: Increasing concerns regarding the sustainability of lithium sources, due to their limited availability and consequent expected price increase, have raised awareness of the importance of developing alternative energy-storage candidates that can sustain the ever-growing energy demand. Furthermore, limitations on the availability of the transition metals used in the manufacturing of cathode materials, together with questionable mining practices, are driving development towards more sustainable elements. Given the uniformly high abundance and cost-effectiveness of sodium, as well as its very suitable redox potential (close to that of lithium), sodium-ion battery technology offers tremendous potential to be a counterpart to lithium-ion batteries (LIBs) in different application scenarios, such as stationary energy storage and low-cost vehicles. This potential is reflected by the major investments that are being made by industry in a wide variety of markets and in diverse material combinations. Despite the associated advantages of being a drop-in replacement for LIBs, there are remarkable differences in the physicochemical properties between sodium and lithium that give rise to different behaviours, for example, different coordination preferences in compounds, desolvation energies, or solubility of the solid–electrolyte interphase inorganic salt components. This demands a more detailed study of the underlying physical and chemical processes occurring in sodium-ion batteries and allows great scope for groundbreaking advances in the field, from lab-scale to scale-up. This roadmap provides an extensive review by experts in academia and industry of the current state of the art in 2021 and the different research directions and strategies currently underway to improve the performance of sodium-ion batteries. The aim is to provide an opinion with respect to the current challenges and opportunities, from the fundamental properties to the practical applications of this technology

Essays On Asset Pricing And Firm Dynamics

University of Minnesota Ph.D. dissertation.March 2020. Major: Business Administration. Advisor: Hengjie Ai. 1 computer file (PDF); vii, 121 pages.My dissertation studies the implications of agency frictions for asset prices and firm dynamics. The first chapter embed an optimal contracting framework into an otherwise standard asset pricing paradigm to resolve some of the challenges in investment and asset pricing literature. The second chapter investigates the effect of agency frictions on CEO compensation, firm size and investment dynamics. In Chapter one "A Dynamic Agency Based Asset Pricing Model with Production", we develop a general equilibrium model based on dynamic agency theory to study investment and asset prices. In our environment, neither firms nor workers can commit to compensation contracts that provide continuation values below their outside options. At the aggregate level, the presence of agency frictions amplifies the market price of risks and allows our model to generate a sizable equity premium with a low level of risk aversion. History dependent labor contracts generate a form of operating leverage and allow our model to match the key features of the aggregate and cross-section of investment and equity returns in the data. A variance decomposition of investment into discount rate news and cash flow news supports the mechanism of our model. In Chapter two, "Firm Dynamics under Limited Commitment", we present a general equilibrium model with twosided limited commitment that helps account for the observed heterogeneity in firms’ investment, payout and CEO-compensation policies. In the model, shareholders cannot commit to holding negative net present value projects, and managers cannot commit to compensation plans that yield life-time utility lower than their outside options. Firms operate identical constant return to scale technologies with i.i.d. productivity growth. Our model endogenously generates power laws in firm size and CEO compensation and explains the differences in their empirical distributions. We also show that the model is able to quantitatively account for the salient features of firms’ growth dynamics, the observed negative relationship between firms’ investment rate and size, and the positive relationship between firms’ size and their dividend and CEO payout

Performance analysis of multi-rate signal processing digital filters on FPGA

Abstract Multi-rate signal processing, an important part of the design of a digital frequency converter, is realized mainly based on interpolation and decimation, which match the sampling rate between the baseband and high-frequency processing side, especially in down conversion. However, the design of a digital filter is important for realizing multi-rate interpolation and decimation, which is highlighted in this paper. To analyze the digital filter performance in multi-rate signal processing, the ordinary finite impulse response (FIR) filter and more efficient digital filter are discussed respectively. The ordinary FIR filters use a Hamming window to design, while a more efficient digital filter includes a cascaded integrate comb (CIC) and half-band filter. Sampling rate transformation factor is 12 in this design, which is cascaded by three stages. Each stage corresponding to the conversion factor is 3, 2, and 2. Both of these design methods are implemented on the FPGA development board. The hardware resource occupancy and the error rate of the signal amplitude in decimation show that the efficient digital filter is superior to the digital filter designed by the Hamming window in the real-time processing

Finite-Time Bounded Synchronization of the Growing Complex Network with Nondelayed and Delayed Coupling

The objective of this paper is to discuss finite-time bounded synchronization for a class of the growing complex network with nondelayed and delayed coupling. In order to realize finite-time synchronization of complex networks, a new finite-time stable theory is proposed; effective criteria are developed to realize synchronization of the growing complex dynamical network in finite time. Moreover, the error of two growing networks is bounded simultaneously in the process of finite-time synchronization. Finally, some numerical examples are provided to verify the theoretical results established in this paper