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Energy Dissipation Capacity of Structural Components
No full textInput energy has long been recognized as a better demand parameter for expressing the effects of ground motions on structures as compared to accelerations (forces) or displacements (deformations) induced by ground motions. Previous research has clearly revealed the weak dependence of spectral input energy on viscous damping ratio and inelastic response, which is a clear advantage for expressing the demand of ground motions on structural systems in performing analysis and design. Moreover, the duration of the earthquake excitation, hence the magnitude of the causative earthquake is well represented by the input energy spectrum, which is a function of the initial structural period and ground motion intensity only. The main missing point in energy-based approaches however is the energy dissipation capacity of structural components. A method is proposed in this study for estimating the energy dissipation capacity of structural components, particularly the plastic hinges of flexural members in structural frames. The energy dissipation capacity of a plastic hinge is expressed in terms of a capacity curve, which gives the number of equivalent full cycles at the maximum deformation (i.e. the maximum rotation or curvature) at which the cyclic energy dissipation capacity falls below a limiting performance target. The proposed procedure is tested on a full-scale reinforced concrete column, tested under both constant amplitude and variable amplitude loading protocols
COMPREHENSIVE INVESTIGATION OF AUXILIARY TIMBER ELEMENTS IN THE 15TH-16TH CENTURY STONE MASONRY OTTOMAN STRUCTURES
No full textA stochastic phase-field approach for the failure of rubberlike materials
No full textAlthough in the classical phase-field approach the assumption is a homogenized distribution of the critical energy release rate over the material, leading to catastrophic failure and hence brittle fracture; the experimental evidence regarding the fracture behaviour of rubber-like materials implies ductile-like progressive failure. To characterize and model the functioning of rubber-like materials, the phenomena is extremely vital as fatigue failure crack growth is holds substantial importance in engineering design processes. In this work, the critical entropic energy distribution is taken as a spatially varying material parameter to represent the stochasticity. Conducting a series of fracture experiments using die-cut v-shaped double edge notched specimens of unfilled styrene-butadiene rubber (SBR), stochastic properties of the rubbers were able to be shown over loaddisplacement curves. Results demonstrated ductile-like fracture in contrast with laser-cut specimens where the data obtained indicated the exhibition of a pronounced tendency towards sharp brittle fracture. Analyzing the results of the work, It is observed that ductile-like fracture propagates intermittently and follows intricate irregular paths even on homogeneous specimens. This complex behaviour challenges the conventional notions of fracture mechanics in rubber-like materials and provides significant insight for engineering design and materials science, leading the research to pave the way for more reliable engineering applications
HELP4DNS: Leveraging the programmable data plane for effective and robust defense against DDoS attacks on DNS
No full textDNS is a critical component of the Internet infrastructure, and securing it has been an active research domain, with a particular emphasis on countering DDoS attacks. With the rise of programmable data planes, novel defensive strategies taking advantage of their flexibility and line-rate packet processing capabilities have been developed to counter a range of DDoS attacks. This study proposes two novel methodologies against DNS flood and DNS amplification attacks within programmable data planes using P4. The first approach involves constraining the concurrent active queries per client to mitigate DNS query flood attacks, thereby ensuring that clients generating a high volume of requests adhere to predetermined limits. The proposed method uses concurrent query limits per client by employing a modified token bucket algorithm within an updatable Bloom filter data structure to track and limit DNS queries. This approach effectively rate limits malicious client requests, preventing server overload and safeguarding benign users from any resulting disruptions. The second method is a DNS firewall implemented on the P4 switch situated on the victim's side to prevent DNS amplification attacks. The proposed firewall utilizes an updatable Bloom filter on a P4 switch, enabling stateful processing of DNS queries at the application layer. Additionally, it supports stateful tracking of fragmented DNS responses resulting from the Extension Mechanisms for DNS. While IP fragmentation occurs at the IP layer, the proposed approach achieves stateful tracking of fragmented DNS responses at the application layer. In this manner, only the responses corresponding to legitimate requests are forwarded among the received DNS responses by the victim, while responses stemming from DNS amplification attacks are blocked. Evaluation results have demonstrated that the proposed approach effectively blocks high-volume DNS amplification attack packets with minimal memory space requirements
Drivers and challenges of solar photovoltaics (PV) adoption by Turkish manufacturers
No full textThis study addresses the critical gap in literature caused by previous qualitative studies on PV adoption focusing primarily on households, which have limited access to specific industry sectors across different countries. As far as we know, no other research has investigated the manufacturing and industrial firms' perspective on Renewable energy and, specifically, PV adaptation in T & uuml;rkiye. We use a qualitative semi-structured survey approach accommodated in Turkish Organized Industrial Zones. According to the interviews carried out within the scope of this study, an increase in electricity prices and a decrease in the payback period by PV installment are seen as the most critical drivers of PV adoption in the manufacturing sector. Energy security concerns and climate change policies also help increase the pace of PV adaptation. One of the biggest challenges in PV adoption seems to be technical challenges due to the limited capacity of the transformer, bureaucratic problems due to PV applications, supply side problems due to long wait times by the suppliers, knowledge and information problems, architectural and space problem that are also linked to the legal constraints and financial difficulties due to the lack of access to credit due to the macroeconomic situation of the country
Effect of EDOT contribution on the electrochromic and capacitive properties of edot-carbazole based electrochromic polymer: Electrochromic and supercapacitor device applications
No full text3,4-ethylenedioxythiophene (EDOT) based donor-acceptor-donor (DAD) type conjugated polymers generally have extraordinary electrochromic properties due to the excellent nature of the EDOT unit. This work investigates the electrochromic properties of such a system; EDOT-Carbazole-EDOT (ECE) based DAD type of conjugated polymer. Electrochemically synthesized homopolymer film (PECE) showed multichromic behavior with excellent optical properties such as 34 % of optical contrast, subsecond switching response (0.96 s at 478 nm), high coloration efficiency (519 cm2/C at 478 nm) and remarkable specific capacitance (3.04 F/cm2). Inserting more EDOT units into the polymer matrix of PECE via electrochemical synthesis altered the spectral and capacitive behaviors of the resulting copolymers. 2:1 (ECE:EDOT) feeded copolymer exhibited better electrochromic performance than equal feeded copolymer. On the other hand, the capacitive range and capacitance stability were significantly enhanced as the EDOT unit increased in the copolymer matrix. PECE and its copolymers were used to construct dual-type electrochromic devices with poly(3, 4-ethylenedioxythiophene) (PEDOT). ECDs of PECE and copolymers exhibited superior stability upon many switchings, with subsecond switching responses. Furthermore, ECDs can be switched effectively even at the scan rate of 500 mV/s without any loss in charge/discharge amounts. Finally, electrochromic supercapacitor device applications were performed, and a 1.5 V-LED was lighted for up to 25 s with the copolymer supercapacitor device
Ten new insights in climate science 2024
No full textThe years 2023 and 2024 were characterized by unprecedented warming across the globe, underscoring the urgency of climate action. Robust science advice for decision makers on subjects as complex as climate change requires deep cross- and interdisciplinary understanding. However, navigating the ever-expanding and diverse peer-reviewed literature on climate change is enormously challenging for individual researchers. We elicited expert input through an online questionnaire (188 respondents from 45 countries) and prioritized 10 key advances in climate-change research with high policy relevance. The insights span a wide range of areas, from changes in methane and aerosol emissions to the factors shaping citizens’ acceptance of climate policies. This synthesis and communications effort forms the basis for a science-policy report distributed to party delegations ahead of the 29th session of the Conference of the Parties (COP29) to inform their positions and arguments on critical issues, including heat-adaptation planning, comprehensive mitigation strategies, and strengthened governance in energy-transition minerals value chains
Preface for the special issue on February 6, 2023, Kahramanmaraş-Türkiye earthquakes (Mw=7.8 and 7.5): reconnaissance missions and first observations
No full textTemporal grating of semiconductor nanoantennas for high-density solar energy harvesting
No full textAchieving ultra-compact, high-efficiency solar harvesting remains a central challenge in nanophotonics. Here, we demonstrate an active semiconductor nanoantenna design that dramatically enhances solar energy density through synchronized temporal modulation of its optical susceptibility. Unlike conventional passive nanoantennas, our approach uses an intensity-modulated pump laser to dynamically vary the free-electron density, creating a ‘plasmonic chirp’ that matches the round-trip travel time of incident photons within the nanoantenna. This time-synchronized gating leads to a form of temporal trapping, which substantially increases photon confinement and absorption. Experimentally verified numerical simulations predict solar energy densities exceeding 10 GJ m−3—over an order of magnitude higher than standard passive designs. In addition to a comprehensive but compact numerical model, we also propose an expanded experimental platform to realize the core mechanism at scale. This work introduces a novel method for high-density solar energy harvesting at the nanoscale, with potential to significantly advance next-generation photovoltaics and optoelectronic devices
Effects of High Hydrostatic Pressure (HHP) on the Extraction and Functional Characteristics of Chickpea Proteins and Saponins
No full textThis study investigated the influence of High Hydrostatic Pressure (HHP) on the extraction of proteins and saponins from chickpeas, as well as its effects on their functional properties. HHP was applied at two pressure levels (200 and 400 MPa) at 40 degrees C for 5 min and compared with conventional heating (90 degrees C for 5 min, no pressure). The results showed that HHP significantly improved the extraction of soluble proteins and saponins, especially at 200 MPa. At higher pressure (400 MPa), there was a slight decrease in extraction due to the possible formation of protein aggregates. The study also found that HHP-treated samples had better foaming and emulsifying abilities, which are important for food applications. Emulsions produced under HHP were more stable than those from the control treatment. Overall, HHP proved to be an effective method for improving both the extraction and functionality of chickpea bioactives, with potential applications in food