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Seismic Performance of High-rise Concrete Buildings in Chile
Lagos, Rene,Kupfer, Marianne,Lindenberg, Jorge,Bonelli, Patricio,Saragoni, Rodolfo,Guendelman, Tomas,Massone, Leonardo,Boroschek, Ruben,Yanez, Fernando Council on Tall Building and Urban Habitat Korea 2012 International journal of high-rise buildings Vol.1 No.3
Chile is characterized by the largest seismicity in the world which produces strong earthquakes every $83{\pm}9years$ in the Central part of Chile, where it is located Santiago, the capital of Chile. The short interval between large earthquakes magnitude 8.5 has conditioned the Chilean seismic design practice to achieve almost operational performance level, despite the fact that the Chilean Code declares a scope of life safe performance level. Several Indexes have been widely used throughout the years in Chile to evaluate the structural characteristics of concrete buildings, with the intent to find a correlation between general structural conception and successful seismic performance. The Indexes presented are related only to global response of buildings under earthquake loads and not to the behavior or design of individual elements. A correlation between displacement demand and seismic structural damage is presented, using the index $H_o/T$ and the concrete compressive strain ${\varepsilon}_c$. Also the Chilean seismic design codes pre and post 2010 Maule earthquake are reviewed and the practice in seismic design vs Performance Based Design is presented. Performance Based Design procedures are not included in the Chilean seismic design code for buildings, nevertheless the earthquake experience has shown that the response of the Chilean buildings has been close to operational. This can be attributed to the fact that the drift of most engineered buildings designed in accordance with the Chilean practice falls below 0.5%. It is also known by experience that for frequent and even occasional earthquakes, buildings responded elastically and thus with "fully operational" performance. Taking the above into account, it can be said that, although the "basic objective" of the Chilean code is similar to the SEAOC VISION2000 criteria, the actual performance for normal buildings is closer to the "Essential/Hazardous objective".
Cellulose-based Composites Prepared by Two-step Extrusion from Miscanthus Grass and Cellulose Esters
Yuanxi Liu,Alexander Feldner,Robert Kupfer,Martin Zahel,Maik Gude,Tiemo Arndt 한국섬유공학회 2022 Fibers and polymers Vol.23 No.11
Natural fibres from regional plants like miscanthus grass have gained a lot attention as a replacement of syntheticfibres due to their eco-friendly nature, abundant local availability, low cost, reducing food versus fuel competition and theirapplications in bio-based composites. Nevertheless, the polar nature of natural fibres usually leads to a weak interfacialcompatibility with hydrophobic thermoplastic matrices, resulting in poor strengths of the composites. In our study a way toprepare cellulose-based composites in a two-step extrusion process is investigated. The cellulosic fibres are first fibrillatedfrom refined miscanthus fibres through (chemo-)thermomechanical pulping by extrusion. The fibre morphology includingthe aspect ratio is measured by field flow fractionation with optical measurement system. Infrared spectroscopy is applied toanalyse the degree of substitution (DS) values quantitatively. In a second extrusion step, the modified cellulosic fibres arecompounded with cellulose acetate (CA) and cellulose acetate butyrate (CAB) to cellulose-based injection-mouldablecomposites. The thermal, rheological, mechanical and morphological properties are characterised to analyse the composites. The properties of the composites prepared by this method are compared with their unmodified grades and with compositesusing drop-in biopolymers bio-based polypropylene (bio-PP) and bio-based polyethylene (bio-PE) as matrices. It shows, thatthe mechanical properties of mechanically fibrillated cellulose fibres reinforced CA are comparable to glass fibre reinforcedpolypropylene with similar fibre weight content. We have also seen, that the influence of mechanical fibrillation exceeds theinfluence of the chemical modification.
이건학,손덕주,김동균,John A. Kupfer,김대현 한국지형학회 2024 한국지형학회지 Vol.31 No.1
Biogeomorphology is an academic discipline that focuses on the feedback processes between organisms and their environment. However, biogeomorphologists have been mainly interested in revealing the one-way influence of ecosystem engineers on their habitat environment. The present paper discusses why the complete biogeomorphological reciprocity has been studied less often. We first propose a conceptual model that integrates the ecosystem engineering and niche construction concepts. We then present five aspects as to why reciprocal interactions between engineer species and their environment are a difficult to study: spatial scale dependency, temporal scale dependency, species dependency, life cycle stage dependency, and habitat context dependency. These specific difficulties are further demonstrated by fluvial biogeomorphological case studies. Although studying fluvial biogeomorphological feedbacks is challenging, developing a clear understanding of the categorical issues will be the first step to resolving such difficulties.
Confirmation of Large Super-fast Rotator (144977) 2005 EC <sub>127</sub>
Chang, Chan-Kao,Lin, Hsing-Wen,Ip, Wing-Huen,Lin, Zhong-Yi,Kupfer, Thomas,Prince, Thomas A.,Ye, Quan-Zhi,Laher, Russ R.,Lee, Hee-Jae,Moon, Hong-Kyu American Astronomical Society 2017 ASTROPHYSICAL JOURNAL LETTERS - Vol.840 No.2
<P>(144977) 2005 EC127 is a V-/A-type inner-main-belt asteroid with a diameter of 0.6 +/- 0.1. km. Asteroids of this size are believed to have rubble-pile structure, and therefore cannot have a rotation period shorter than 2.2 hr. However, our measurements show that asteroid 2005 EC127 completes one rotation in 1.65 +/- 0.01. hr with a peakto-peak light-curve variation of similar to 0.5. mag. Therefore, this asteroid is identified as a large super-fast rotator. Either a rubble-pile asteroid with a bulk density of rho similar to 6 g. cm(-3) or an asteroid with an internal cohesion of 47 +/- 30. Pa can explain 2005 EC127. However, the scenario of high bulk density is very unlikely for asteroids. To date, only six large super-fast rotators, including 2005 EC127, have been reported, and this number is very small when compared with the much more numerous fast rotators. We also note that none of the six reporting large SFRs are classified as C-type asteroids.</P>
Mangoni, Matteo E.,Traboulsie, Achraf,Leoni, Anne-Laure,Couette, Brigitte,Marger, Laurine,Le Quang, Khai,Kupfer, Elodie,Cohen-Solal, Anne,Vilar, José,Shin, Hee-Sup,Escande, Denis,Charpentier, Fl Ovid Technologies Wolters Kluwer -American Heart A 2006 Circulation research Vol.98 No.11
<P>The generation of the mammalian heartbeat is a complex and vital function requiring multiple and coordinated ionic channel activities. The functional role of low-voltage activated (LVA) T-type calcium channels in the pacemaker activity of the sinoatrial node (SAN) is, to date, unresolved. Here we show that disruption of the gene coding for CaV3.1/alpha1G T-type calcium channels (cacna1g) abolishes T-type calcium current (I(Ca,T)) in isolated cells from the SAN and the atrioventricular node without affecting the L-type Ca2+ current (I(Ca,L)). By using telemetric electrocardiograms on unrestrained mice and intracardiac recordings, we find that cacna1g inactivation causes bradycardia and delays atrioventricular conduction without affecting the excitability of the right atrium. Consistently, no I(Ca,T) was detected in right atrium myocytes in both wild-type and CaV3.1(-/-) mice. Furthermore, inactivation of cacna1g significantly slowed the intrinsic in vivo heart rate, prolonged the SAN recovery time, and slowed pacemaker activity of individual SAN cells through a reduction of the slope of the diastolic depolarization. Our results demonstrate that CaV3.1/T-type Ca2+ channels contribute to SAN pacemaker activity and atrioventricular conduction.</P>