The current fire protection measures in buildings do not account for all contemporary fire hazard issues, which has made fire safety a growing concern. Therefore, this paper aims to present a critical review of current fire protection measures and their applicability to address current challenges relating to fire hazards in buildings.,To overcome fire hazards in buildings, impact of fire hazards is also reviewed to set the context for fire protection measures. Based on the review, an integrated framework for mitigation of fire hazards is proposed. The proposed framework involves enhancement of fire safety in four key areas: fire protection features in buildings, regulation and enforcement, consumer awareness and technology and resources advancement. Detailed strategies on improving fire safety in buildings in these four key areas are presented, and future research and training needs are identified.,Current fire protection measures lead to an unquantified level of fire safety in buildings, provide minimal strategies to mitigate fire hazard and do not account for contemporary fire hazard issues. Implementing key measures that include reliable fire protection systems, proper regulation and enforcement of building code provisions, enhancement of public awareness and proper use of technology and resources is key to mitigating fire hazard in buildings. Major research and training required to improve fire safety in buildings include developing cost-effective fire suppression systems and rational fire design approaches, characterizing new materials and developing performance-based codes.,The proposed framework encompasses both prevention and management of fire hazard. To demonstrate the applicability of this framework in improving fire safety in buildings, major limitations of current fire protection measures are identified, and detailed strategies are provided to address these limitations using proposed fire safety framework.,Fire represents a severe hazard in both developing and developed countries and poses significant threat to life, structure, property and environment. The proposed framework has social implications as it addresses some of the current challenges relating to fire hazard in buildings and will enhance overall fire safety.,The novelty of proposed framework lies in encompassing both prevention and management of fire hazard. This is unlike current fire safety improvement strategies, which focus only on improving fire protection features in buildings (i.e. managing impact of fire hazard) using performance-based codes. To demonstrate the applicability of this framework in improving fire safety in buildings, major limitations of current fire protection measures are identified and detailed strategies are provided to address these limitations using proposed fire safety framework. Special emphasis is given to cost-effectiveness of proposed strategies, and research and training needs for further enhancing building fire safety are identified.

Fire hazard in buildings: review, assessment and strategies for improving fire safety

Over the last few years, interference has been a major hurdle for successfully implementing various end-user applications in the fifth-generation (5G) of wireless networks. During this era, several communication protocols and standards have been developed and used by the community. However, interference persists, keeping given quality of service (QoS) provision to end-users for different 5G applications. To mitigate the issues mentioned above, in this paper, we present an in-depth survey of state-of-the-art non-orthogonal multiple access (NOMA) variants having power and code domains as the backbone for interference mitigation, resource allocations, and QoS management in the 5G environment. These are future smart communication and supported by device-to-device (D2D), cooperative communication (CC), multiple-input and multiple-output (MIMO), and heterogeneous networks (HetNets). From the existing literature, it has been observed that NOMA can resolve most of the issues in the existing proposals to provide contention-based grant-free transmissions between different devices. The key differences between the orthogonal multiple access (OMA) and NOMA in 5G are also discussed in detail. Moreover, several open issues and research challenges of NOMA-based applications are analyzed. Finally, a comparative analysis of different existing proposals is also discussed to provide deep insights to the readers.

/pdf/a-systematic-review-on-noma-variants-for-5g-and-beyond-55xdyacniv.pdf

A Systematic Review on NOMA Variants for 5G and Beyond

Functionally graded materials (FGM), whose structural properties are varied along their volume to perform an intended function, have a full application in the marine industry Under the corrosive marine environment, a corrosion-resistant alloy of duplex stainless steel, functionally graded with carbon-manganese steel along with the inner layer, is proposed here for the risers The interface strength of FGM, fabricated using Cold Metal Transfer – gas metal arc welding, based on Wire Arc Additive Manufacturing (WAAM) in the lab-scale, is compared with an X-52 Carbon Manganese steel to highlight the superiority of the proposed FGM The role of metal transfer characteristics on the microstructure formation at the layers adjacent to the interface is analyzed and correlated with the voltage-current waveform those obtained during the deposition process Based on the experimental studies carried out, it is seen that the yield strength of the FGM interface is very close to that of X52 steel, with a marginal increase of about 6% in the ultimate strength Based on the energy dispersive X-ray analysis, it is observed that there is no enrichment of chromium across the interface towards the carbon-manganese steel side It is vital for the corrosion-resistance of duplex stainless steel Proposed FGM shows advantages both in strength and durability and hence seen as a promising candidate for marine riser applications

Wire arc additive manufacturing of functionally graded material for marine risers

This work presents a comprehensive analysis of the effects of strain and strain rate on the adiabatic heating and the mechanical behavior of a CoCrFeMnNi high-entropy alloy (HEA). In this investigation, compression tests were carried out at quasi-static and dynamic strain rates. The temperature of the specimens was measured using high speed infrared thermography. The high strain rate tests were conducted with a Split Hopkinson Pressure Bar, and the tests at lower strain rates were performed using a universal testing machine. The material exhibited a positive strain rate sensitivity, as true stress–strain plots were shifted upwards with the increase in strain rate. With exception of the isothermal tests, temperature rise and the Taylor–Quinney coefficient (β) were noticeably similar for the investigated strain rates. This study shows that the common assumption that β can be considered 0.9 and constant is possibly not very accurate for the CoCrFeMnNi alloy. The β is influenced by at least strain and strain rate.

/pdf/effects-of-adiabatic-heating-and-strain-rate-on-the-dynamic-53eotm38j8.pdf

Effects of Adiabatic Heating and Strain Rate on the Dynamic Response of a CoCrFeMnNi High-Entropy Alloy

System-level integration of a midinfrared carbon dioxide (CO2) sensor system based on tunable laser absorption spectroscopy (TLAS) was realized for the analysis of dissolved CO2 in seawater, employing an interband cascade laser (ICL) centered at 4319 nm and a multipass cell (MPC) with an optical path length of 29.8 m. At a low measurement pressure of 30 Torr, three absorption lines of 12CO2 were selected to realize different measurement ranges and a 13CO2 absorption line was targeted for simultaneous isotopic abundance analysis of δ13CO2. The sensor system was compactly integrated into a standalone system with automatic operation for underwater field deployment, and the working process was controlled by a specially designed electrical system. A gas-liquid separator system was developed for CO2 extraction from water, and a pressure-control mechanism with two operation modes (i.e., static and dynamic modes) was proposed to make the sensor system applicable under a deep-sea environment. A series of experiments were carried out in the laboratory for performance assessment of the developed sensor system employed for the analysis of dissolved CO2 in water. The sensor was deployed for a field test for natural gas hydrates exploration at an underwater depth of 0-2000 m in the South China Sea, with the sensor operating normally during the deployment.

Midinfrared Sensor System Based on Tunable Laser Absorption Spectroscopy for Dissolved Carbon Dioxide Analysis in the South China Sea: System-Level Integration and Deployment.

Design Aids of Offshore Structures Under Special Environmental Loads including Fire Resistance

Combustible facade systems used in modern buildings envelops have received much attention in recent times due to their involvement in propagation of accidental fires in such buildings. This study presents findings from four full-scale real fire experiments performed on a three-story structure (each room being of plan dimensions $$10'\times 20'$$
 and story height $$10'$$
 ) with combustible facade systems involving firestops, aluminum composite panels and glass. Two experiments simulated external fire-spread mechanism through the leap-frog effect (one with external fire source and one with internal fire source). The other two experiments were designed to study internal fire spread mechanism due to failure of firestops, a crucial design component of facade systems which is overlooked by most standardized facade fire tests. The experiments indicated that a facade fire can reach from one story to the next in about 3 min and hence, can severely limit the response and egress time for higher floors of a building. Further, the experiments showed that the facade system was exposed to heat flux levels in excess of $$100\,\mathrm{kW}/\mathrm{m}^{2}$$
 with maximum temperatures reaching $$1000^{\circ }\mathrm{C}$$
 . The existing testing standards consider lower incident flux levels and the gas burners used in most existing test methods can reach maximum temperatures of around $$700^{\circ }\mathrm{C}$$
 only. These findings indicate a significant gap between current testing standards and real fire performance of facade systems. A study of failure mechanisms of individual components during the experiments showed the need of considering the system in its entirety rather than performing component level testing. The importance of firestops also became evident through these experiments. Properly designed firestop system ensured good compartmentation and prevented spread of fire to the upper floors, whereas improper firestop allowed fire to spread easily to upper floors. It is expected that the insights presented in this study will be useful to improve facade designs as well as to develop more robust testing procedures.

https://link.springer.com/content/pdf/10.1007/s10694-019-00943-4.pdf

Performance of Combustible Facade Systems with Glass, ACP and Firestops in Full-Scale, Real Fire Experiments

Purpose




Reinforced concrete structural frames with masonry infills (infill-frames) are commonly used for construction worldwide. While the behavior of such frames has been studied extensively in the context of earthquake loading, studies related to their fire performance are limited. Therefore, this study aims to characterize the behavior of infill-frames under fire exposure by presenting a state-of-the-art literature review of the same.




Design/methodology/approach




Both experimental and computational studies have been included with a special emphasis on numerical modeling (simplified as well as advanced). The cold behavior of the infill-frame and its design requirements in case of fire exposure are first reviewed to set the context. Subsequently, the applicability of numerical modeling strategies developed for modeling cold infill-frames to simulate their behavior under fire is critically examined.




Findings




The major hurdles in developing generic numerical models for analyzing thermo-mechanical behavior of infill-frames are identified as: lack of temperature-dependent material properties, scarcity of experimental studies for validation and idealizations in coupling between thermal and structural analysis.




Originality value




This study presents one of the most popular research problems connected with practical and reliable utilization of numerical models, as a good alternative to expensive traditional furnace testing, in assessing fire resistance of infill-frames. It highlights major challenges in thermo-mechanical modeling of infill-frames and critically reviews the available approaches for modeling infill-frames subjected to fire.

Numerical modeling of structural frames with infills subjected to thermal exposure: State-of-the-art review

This article presents a framework based on the direct stiffness method for nonlinear thermo-mechanical analysis of reinforced concrete plane frames subjected to fire. It accounts for geometric nonl...

Nonlinear analysis of reinforced concrete plane frames exposed to fire using direct stiffness method

Device-to-Device (D2D) communications underlaying Unmanned aerial vehicle (UAV) with its mobility extend the coverage and improve the data rate. In this paper, we propose an energy management scheme for wireless powered D2D users with NOMA underlaying full-duplex (FD) UAV. Here, the cellular transmitters (CTs) and D2D transmitters (DDTs) first harvest energy from the radio frequency (RF) signals of the UAV. Then, the CT communicates with the cellular receivers (CRs) using the FD-UAV as a relay. On the other hand, DDT communicates with its two D2D receivers (DDRs) using the NOMA. We formulate the problem as a mixed-integer non-linear programming (MINLP) form and then divide it into two sub-problems. In the first sub-problem, an optimal value of time allocation for energy harvesting (EH) for DMG is estimated, whereas, in the second subproblem, the power of DDT in each DMG is optimized using the variable changing technique. Finally, the joint time allocation and power control scheme is proposed to achieve the maximum energy-efficiency (EE). Numerical results demonstrated that the proposed scheme achieves better results as compared to the existing conventional NOMA and orthogonal multiple access (OMA) schemes.

Gaurav Srivastava

Papers

Design Aids of Offshore Structures Under Special Environmental Loads including Fire Resistance

Performance of Combustible Facade Systems with Glass, ACP and Firestops in Full-Scale, Real Fire Experiments

Numerical modeling of structural frames with infills subjected to thermal exposure: State-of-the-art review

Nonlinear analysis of reinforced concrete plane frames exposed to fire using direct stiffness method

Energy management scheme for wireless powered D2D users with NOMA underlaying full duplex UAV