Borsa Istanbul’da piyasa etkinliginin analizi : Harvey gogrusallik testi

Market efficiency is the most important factor affecting the situation as to whether to obtain excessive profits of the investors. Working in BIST-100 Index and sub-indices with the Industrial, Technology, and Financial Services Index of returns, whether it is a linear structure is examined via Harvey linearity test. Used Harvey linearity test, beside other tests analysis linearity without any pre-condition. This increases the power of the test. The data set used in this study is the period between 07.03.2000 and 09.22.2015 consists of 3723 observation. The results of the study say that the analyzed variables are nonlinear. The excess returns are concerned. Therefore, according to efficient market hypothesis, by using previous information excessive profits can be obtained in the markets.peer-reviewe

turboTDDFT - A code for the simulation of molecular spectra using the Liouville-Lanczos approach to time-dependent density-functional perturbation theory

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Characteristics of Strong Ground Motions in the 30 October 2020, MW6.9 Aegean Sea Earthquake

The eastern parts of the Aegean Sea were struck by a destructive MW 6.9 earthquake on 30 October 2020 at 11:51:27 UTC. The earthquake ruptured an East-West trending normal fault in the Aegean Sea between the northern coast of Samos Island and the southern coast of İzmir and also triggered a medium level tsunami and thousands of aftershocks across the region. 119 fatalities, 1,051 injuries, and many collapsed buildings were reported due to the earthquake in the affected region. The most catastrophic consequences of the earthquake were registered in the Bayraklı and Bornova districts, which are built on a deep alluvial Basin approximately 60–70 km away from the epicentre of the mainshock. This paper explains the damage with an extensive dataset of ground motion records of the mainshock and aftershocks, which are provided by both Greek and Turkish networks. A set of ground motion parameters such as peak ordinates, spectral quantities, intensity measures and duration parameters are calculated and analysed. The closest softer soil station in Samos Island produces the highest peak ground acceleration and velocity. The ground motion models employed commonly for the region overestimate the observed data beyond 60–70 km of Joyner-Boore distance except for the recently published local ground motion model, which utilises local earthquakes in the derivation of the model. Contrary to expectations, stiff soil recordings exhibit considerable spectral accelerations in the long period region, similar to those in soft soils. The calculated ground motion parameters are correlated with the results of the hybrid reconnaissance mission, organized by the Earthquake Engineering Field Investigation Team (EEFIT). Although the peak values and regarded intensity measures clearly highlight the variability in soil conditions in the most damaged area (Bayraklı and Bornova), velocity-based ground motion parameters seem to be the more responsive damage indicators. The spectral shapes of the normalised response spectra in the İzmir Basin are not compatible with the 2018 Turkish seismic code spectrum whereas their response spectra are below the 475-years return period design spectra provided in outdated and current Turkish seismic codes

Hybrid EEFIT mission to february 2023 Kahramanmaraş earthquake sequence

The southwestern part of Türkiye was hit on 6 February 2023 by an Mw 7.8 (epicentre:Pazarcık) and then an Mw 7.5 earthquake (epicentre: Elbistan). The event was followed by tensof thousands of aftershocks including the Mw 6.3 event on 20 February (epicentre: Uzunbağ).This paper reports on the preliminary findings of the mission organised by the UK’s EarthquakeEngineering Field Investigation Team (EEFIT) to the Kahramanmaraş Earthquake sequence ofFebruary 2023. This mission followed a hybrid model, combining field and remote investigationtechniques, to investigate the characteristics of the earthquake sequence, its impact on buildingsand infrastructure, as well as the efficacy of relief, response and recovery operations. The keymessages include that the building stock is hard to categorise which brings along difficulties withdamage assessment, that the recovery and reconstruction require multi-sectoral engagement ofkey stakeholders, and that the auditing and quality control mechanisms within the constructionindustry need revisiting in the way forward for better disaster resilience in Türkiye

Hybrid reconnaissance mission to the 30 October 2020 Aegean sea earthquake and tsunami (Izmir, Turkey & Samos, Greece): description of data collection methods and damage

On 30 October 2020, an earthquake of Mw 6.9 hit the Aegean coasts of Turkey and Greece. The epicentre was some 14 km northeast of Avlakia on Samos Island, and 25 km southwest of Seferihisar, Turkey, triggering also a tsunami. The event has been followed by >4,000 aftershocks up to Mw 5.2 The Earthquake Engineering Field Investigation Team (EEFIT) has immediately gathered a team to conduct a hybrid reconnaissance study,bringing together remote and field investigation techniques. The mission took place between 16 November and 17 December, inclusive of three sets of field study carried out by the field crews for building damage assessment in the affected areas in Turkey and Greece under the coordination of the remote team. The mission also aimed to assess the viability of alternative data sources for an appraisal of the future viability of hybrid missions. This paper summarises the mission setup and findings, and discusses the benefits of and difficulties encountered during this hybrid reconnaissance activity

Structure et dynamique de Te et GeTe liquides et amorphes : simulation par dynamique moléculaire ab initio

Contrairement à la plupart des éléments, les phases liquide et amorphe du tellure se sont avérées être assez mal reproduites par la méthode, pourtant éprouvée, de la dynamique moléculaire ab initio . Les calculs ‘standart’ utilisant la théorie de la fonctionnelle de la densité (DFT) produisent en effet des structures en relatif désaccord avec les expériences de diffraction, en particulier pour ce qui concerne le nombre de premiers voisins et les distances interatomiques, quantités qui apparaissent fortement surestimées dans les simulations. Le tellure étant composant essentiel de la plupart des matériaux à changement de phase (PCMs), cette mauvaise description de ses phases désordonnées soulève d’importantes questions au sujet de la capacité de la dynamique moléculaire ab initio à générer des structures d’amorphe réalistes pour les PCMs. Dans ce travail, nous utilisons la dynamique moléculaire ab initio réalisée à volume constant (valeurs expérimentales) pour simuler la structure et la dynamique du tellure liquide le long de l’anomalie de densité. Nous testons différentes approximations afin de démontrer leur importance sur la structure du liquide et de l’amorphe. En particulier, si l’interaction spin-orbite apparaît au final avoir un effet neutre, le traitement des forces de dispersion fournit une nette amélioration vis-à-vis de calculs récents utilisant des fonctionnelles hybrides, l’ordre atomique local étant fortement modifié dans les deux phases [1]. L’évolution de la structure avec l’anomalie de densité est clairement reliée à la création de nombreuses interconnections entre chaines de tellure, ces chaines étant de plus en plus longues avec l’abaissement de la température. Dans la phase amorphe, les chaines sont pratiquement intactes et présentent des distributions d’angle dièdre originales. Ces modifications sont reflétées dans les propriétés dynamiques, telles que le coefficient de diffusion et la densité d’états vibrationnels. [1] J. Akola, R. O. Jones, S. Kohara, T. Usuki, and E. Bychkov, Phys. Rev. B 81, 094202 (2010).A.R.C. Themoter

Structural properties of diamond nanorods: molecular-dynamics simulations

The structural properties of carbon nanorods obtained from diamond crystal have been investigated by performing molecular-dynamics computer simulations. Calculations have been realized by using an empirical many-body potential energy function for carbon. Diamond nanorods have been generated from three low-index planes of diamond crystal. It has been found that the average coordination number, cross-section geometry, and surface orientation from which the nanorod is generated play a role in the stability of diamond nanorods under heat treatment. The most stable diamond nanorod has been obtained from the (111) surface

Ab Initio Molecular Dynamics Simulation of Liquid and Amorphous Te

Contrary to almost all other elements, liquid and amorphous phases of pure tellurium have proven difficult to simulate using ab initio molecular dynamics. Standard density functional theory calculations yield structures in relatively poor agreement with available diffraction experiments at low temperature, especially regarding first neighbor distance and coordination number, which are strongly overestimated in the simulations. Tellurium being a key component of many phase change materials, this poor structural description of its disordered phases raises important issues about the ability of ab initio molecular dynamics to generate accurate structural models of amorphous phases. In this work, we use ab initio molecular dynamics performed under constant volume (experimental values) conditions to simulate liquid Tellurium structure and dynamics along its density anomaly. We test different exchange correlation functionals and approximations, and show their influence on liquid and amorphous structures. In particular, we show that the treatment of dispersion forces is yielding a clear improvement over recent hybrid functional calculations [1], with significant local order modifications in both phases. Especially, the structure evolution along the density anomaly is shown to be related to the creation of many interconnections between Te chains, these chains having increasing lengths upon temperature reduction. In the amorphous phase, Te chains are almost perfectly isolated with specific dihedral angle distributions. These structural changes are reflected on dynamical properties, such as atomic diffusion coefficient and vibrational density of states. We then apply the same method to revisit the structure of some Te based alloys. [1] J. Akola, R. O. Jones, S. Kohara, T. Usuki, and E. Bychkov, Phys. Rev. B 81, 094202 (2010)

Effects of Casting Speed on Thin Gauge Foil Surface Quality of 8079 Aluminum Alloy Produced by Twin Roll Casting Method

In twin roll casting method, casted strips exhibit centerline segregation due to solidification kinetics. Casting parameters have an essential impact on aluminum’s microstructural properties as segregations. Therefore, these parameters have unfavorable effects on strip and foil products. Moreover, in foil products, pinhole surface defects do exist and reveal themselves as undesirable quality problems. In the present study, 8079 aluminum alloys were produced by twin roll casting method at different casting speeds. Diversified homogenization annealing processes were applied in laboratories for indicating optimum temperature leading to microstructural alterations. In order to analyze the influence of casting speed on foil products, microstructural investigations were accomplished on as-cast specimens and homogenized samples with optical microscope and scanning electron microscope. EDS and XRD analysis were conducted to analyze intermetallic structure inside 8079 alloy. In addition, mechanical tests were carried out for indicating the required temper designation for foil product. Scanning electron microscope analysis was performed on the final product surfaces of thin gauge foil in order to characterize the pinhole surface defect. © 2019, The Indian Institute of Metals - IIM