Typhoon‐induced, highly nonlinear internal solitary waves off the east coast of Korea

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94585/1/grl22467.pd

Effects of Nonuniform Fiber Geometries on the Microstructural Fracture Behavior of Ceramic Matrix Composites

Microstructural fracture behavior of a ceramic matrix composite (CMC) with nonuniformly distributed fibers is studied in the presentation. A comprehensive numerical analysis package to study the effect of nonuniform fiber dimensions and locations on the microstructural fracture behavior is developed. The package starts with an optimization algorithm for generating representative volume element (RVE) models that are statistically equivalent to experimental measurements. Experimentally measured statistical data are used as constraints while the optimization algorithm is running. Virtual springs are utilized between any adjacent fibers to nonuniformly distribute the coated fibers in the RVE model. The virtual spring with the optimization algorithm can efficiently generate multiple RVEs that are statistically identical to each other. Smeared crack approach (SCA) is implemented to consider the fracture behavior of the CMC material in a mesh-objective manner. The RVEs are subjected to tension as well as the shear loading conditions. SCA is capable of predicting different fracture patterns, uniquely defined by not only the fiber arrangement but also the specific loading type. In addition, global stress-strain curves show that the microstructural fracture behavior of the RVEs is highly dependent on the fiber distributions

Potassium ions as a kinetic controller in ionic double layers for hysteresis-free perovskite solar cells

Since ion migration and interaction with external contacts has been regarded as one of the origins for photocurrent density (J)–voltage (V) hysteresis and phase segregation in perovskite solar cells (PSCs) under operational condition, control of ionic movement in organic–inorganic halide perovskites presents a big challenge for achieving hysteresis-free and stable PSCs. As a universal method, potassium doping into bulk perovskite films to minimize or eliminate the hysteresis was proposed. Here, we report direct observation of moderately retarded ion migration in K+-doped (FAPbI3)0.875(CsPbBr3)0.125 perovskite by in situ photoluminescence (PL) imaging. However, more impressive is the effect on the kinetics for generation of the ionic double layer in the vicinity of the contacts as it is reduced by two orders of magnitude on the time scale when devices are doped with K+ as detected by impedance spectroscopy. A significantly reduced hysteresis in the K+-doped perovskite is responsible for more prolonged stability exhibiting ∼96% of initial power conversion efficiency (PCE) after 22 days than relatively short-lived perovskites undoped with K+ ions. This work highlights the clear correlation of ion migration and a fast generation of the double layer close to the contacts with severe hysteresis and long-term instability in PSCs and the importance of K+ ions in reducing the kinetics affecting the ionic attachment to the contact surface

E-beam-enhanced solid-state mechanical amorphization of alpha-quartz: Reducing deformation barrier via localized excess electrons as mobile anions

Under hydrostatic pressure, alpha-quartz undergoes solid-state mechanical amorphization wherein the interpenetration of SiO4 tetrahedra occurs and the material loses crystallinity. This phase transformation requires a high hydrostatic pressure of 14 GPa because the repulsive forces resulting from the ionic nature of the Si-O bonds prevent the severe distortion of the atomic configuration. Herein, we experimentally and computationally demonstrate that e-beam irradiation changes the nature of the interatomic bonds in alpha-quartz and enhances the solid-state mechanical amorphization at nanoscale. Specifically, during in situ uniaxial compression, a larger permanent deformation occurs in alpha-quartz micropillars compressed during e-beam irradiation than in those without e-beam irradiation. Microstructural analysis reveals that the large permanent deformation under e-beam irradiation originates from the enhanced mechanical amorphization of alpha-quartz and the subsequent viscoplastic deformation of the amorphized region. Further, atomic-scale simulations suggest that the delocalized excess electrons introduced by e-beam irradiation move to highly distorted atomic configurations and alleviate the repulsive force, thus reducing the barrier to the solid-state mechanical amorphization. These findings deepen our understanding of electron-matter interactions and can be extended to new glass forming and processing technologies at nano- and microscale.Comment: 24 pages, 6 figure

A Grid Web Portal for Aerospace

A wind tunnel simulation requires high-performance computing power like supercomputers and deep knowledge of this subject. Those requirements make win tunnel simulation difficult. Grid technology will make these difficulties simpler by providing easy to use grid web portal. By using grid web portal, scientist can execute simulation and access to highperformance computing power without any serious difficulties. In this paper will present a grid web portal for a wind tunnel simulation that is used in Aerospace area.OAIID:oai:osos.snu.ac.kr:snu2006-01/104/0000004648/27SEQ:27PERF_CD:SNU2006-01EVAL_ITEM_CD:104USER_ID:0000004648ADJUST_YN:NEMP_ID:A001138DEPT_CD:446CITE_RATE:0FILENAME:A Grid Web Portal for Aerospace.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]:

The Differential Effects of Acute Right- vs. Left-Sided Vestibular Deafferentation on Spatial Cognition in Unilateral Labyrinthectomized Mice

This study aimed to investigate the disparity in locomotor and spatial memory deficits caused by left- or right-sided unilateral vestibular deafferentation (UVD) using a mouse model of unilateral labyrinthectomy (UL) and to examine the effects of galvanic vestibular stimulation (GVS) on the deficits over 14 days. Five experimental groups were established: the left-sided and right-sided UL (Lt.-UL and Rt.-UL) groups, left-sided and right-sided UL with bipolar GVS with the cathode on the lesion side (Lt.-GVS and Rt.-GVS) groups, and a control group with sham surgery. We assessed the locomotor and cognitive-behavioral functions using the open field (OF), Y maze, and Morris water maze (MWM) tests before (baseline) and 3, 7, and 14 days after surgical UL in each group. On postoperative day (POD) 3, locomotion and spatial working memory were more impaired in the Lt.-UL group compared with the Rt.-UL group (p < 0.01, Tamhane test). On POD 7, there was a substantial difference between the groups; the locomotion and spatial navigation of the Lt.-UL group recovered significantly more slowly compared with those of the Rt.-UL group. Although the differences in the short-term spatial cognition and motor coordination were resolved by POD 14, the long-term spatial navigation deficits assessed by the MWM were significantly worse in the Lt.-UL group compared with the Rt.-UL group. GVS intervention accelerated the vestibular compensation in both the Lt.-GVS and Rt.-GVS groups in terms of improvement of locomotion and spatial cognition. The current data imply that right- and left-sided UVD impair spatial cognition and locomotion differently and result in different compensatory patterns. Sequential bipolar GVS when the cathode (stimulating) was assigned to the lesion side accelerated recovery for UVD-induced spatial cognition, which may have implications for managing the patients with spatial cognitive impairment, especially that induced by unilateral peripheral vestibular damage on the dominant side

Hyeonggaeyeongyo-Tang for Treatment of Allergic and Nonallergic Rhinitis: A Prospective, Nonrandomized, Pre-Post Study

Hyeonggaeyeongyo-tang (HYT) is an ancient formula of oriental medicine traditionally used to treat rhinitis; however, clinical evidence has not yet been established. The aim of this study was to investigate the short-term and long-term efficacy and safety of HYT for chronic rhinitis. Adult subjects with chronic rhinitis symptoms were recruited. The subjects received HYT for 4 weeks and had follow-up period of 8 weeks. Any medicines used to treat nasal symptoms were not permitted during the study. The skin prick test was performed to distinguish the subjects with allergic rhinitis from those with nonallergic rhinitis. After treatment, the total nasal symptoms score and the Rhinoconjunctivitis Quality of Life Questionnaire score significantly improved in the whole subject group, in the allergic rhinitis group, and in the nonallergic rhinitis group, with no adverse events. This improvement lasted during a follow-up period of 8 weeks. Total IgE and eosinophil levels showed no significant difference after treatment in the allergic rhinitis group. HYT improved nasal symptoms and quality of life in patients with allergic rhinitis and nonallergic rhinitis. This is the first clinical study to evaluate the use of HYT to treat patients with rhinitis. This trial has been registered with the ClinicalTrials.gov Identifier NCT02477293

Funding structures for Build-to-Suit developments in Brazil: advantages and risks

Empreendimentos build-to-suit são aqueles em que o locador desenvolve um imóvel sob medida para o locatário, que o ocupará pelo prazo previsto em contrato. Dadas as peculiaridades desse tipo de contrato no contexto do real estate, o objetivo deste artigo é analisar as diferentes origens de recursos (fontes de funding) e a forma como eles são empregados (estruturas de funding) para desenvolver os empreendimentos, e discutir as vantagens e riscos dessas estruturas de funding do ponto de vista do empreendedor, que também é o locador. De forma a desenvolver este estudo e formatar as estruturas de funding apresentadas, parte-se de uma revisão das\ud práticas atuais do mercado imobiliário brasileiro (através de notícias veiculadas\ud na mídia e de prospectos de negócios realizados), da literatura brasileira sobre o tema e do conhecimento gerado no Grupo de Real Estate da Escola Politécnica da USP. De maneira a verificar a validade legal das soluções, é realizada uma checagem com\ud base na legislação brasileira e nas normas da Comissão de Valores Mobiliários.\ud Considera-se fontes de funding aquelas tratadas (1) como equity: capital próprio do empreendedor, capital de parceiros (e sócios) no empreendimento na forma de dinheiro ou imóveis (notadamente, o terreno onde será construído o empreendimento), ou investimento de Fundo de Investimento Imobiliário (FII); e (2) como dívida: financiamento bancário, securitização dos recebíveis de aluguéis com CRI ou debêntures. As estruturas de funding apresentadas serão combinações dessas fontes. A análise evidencia que estruturas com financiamento por securitização e emissão de CRI são as mais adequadas de forma geral para os negócios, assim como o investimento completo por FII para negócios de maior porte e nos quais o FII é proprietário direto do empreendimento. \ud Palavras-chave: real estate, build-to-suit, locação, funding, project financeBuild-to-suit real estate assets are tailor made developments for the tenant purposes, who occupies and operates the property for the duration agreed. Given the peculiarities of these contracts and the specificities of the property, this article aims at analyzing the sources of capital and how these funds are mixed and structured for the developments. The article discusses the risks and benefits of each of these funding\ud structures assuming the role of developer. In order to do this study and establish the funding structures shown, the research starts with a review of the current practices in Brazilian real estate market (based on press releases and prospects of deals), of local research papers, and will use the knowledge created at the Real Estate Research Group at Escola Politécnica at Universidade de São Paulo. Since it’s necessary to validate\ud the solutions proposed, Brazilian laws and Comissão de Valores Mobiliários (CVM) norms\ud are reviewed. Funding sources considered will be treated as (1) equity: developers own funds, partnership (via capital or real state – mainly land – investment), or Fundo de Investimento Imobiliário (Brazilian investment structure comparable to REITs); or as (2) debt: banks traditional credit lines, securitization of receivables with CRI emissions\ud , and debt bond emissions. The funding structures presented are mixes of these sources. The analysis shows that the structures best suited for this purpose are those with debt by securitization with CRI emissions, along with the complete investment by a FII but only with large emissions and having the FII as the sole owner of the real estate. \ud Keywords: real estate, build-to-suit, rent, funding, project financ