Nanoscale FeS2 (Pyrite) as a Sustainable Thermoelectric Material

We have synthesized undoped, Co-doped (up to 5%), and Se-doped (up to 4%) FeS₂ materials by mechanical alloying in a planetary ball mill and investigated their thermoelectric properties from room temperature (RT) to 600 K. With decreasing particle size, the undoped FeS₂ samples showed higher electrical conductivity, from 0.02 S cm^?1 for particles with 70 nm grain size up to 3.1 S cm^?1 for the sample with grain size of 16 nm. The Seebeck coefficient of the undoped samples showed a decrease with further grinding, from 128 μV K^?1 at RT for the sample with 70-nm grains down to 101 μV K^?1 for the sample with grain size of 16 nm. The thermal conductivity of the 16-nm undoped sample lay within the range from 1.3 W m^?1 K^?1 at RT to a minimal value of 1.2 W m^?1 K^?1 at 600 K. All doped samples showed improved thermoelectric behavior at 600 K compared with the undoped sample with 16 nm particle size. Cobalt doping modified the p-type semiconducting behavior to n-type and increased the thermal conductivity (2.1 W m^?1 K^?1) but improved the electrical conductivity (41 S cm^?1) and Seebeck coefficient (-129 μV K^?1). Isovalent selenium doping led to a slightly higher thermal conductivity (1.7 W m^?1 K^?1) as well as to an improved electrical conductivity (26 S cm^?1) and Seebeck coefficient (110 μV K^?1). The ZT value of FeS₂ was increased by a factor of five by Co doping and by a factor of three by Se doping.     

Dielectric absorber design for wide band–wide oblique incidence angle using genetic algorithm

With an aim to design a V-shape absorber using a global optimization algorithm, the reflectivity value of the absorber is calculated as a cost function by using an equivalent multilayered absorber model, and is minimized by the optimization algorithm. Both normal and oblique incidences of plane wave are analyzed. The optimization parameters are the relative permittivity and the length of the multilayered absorber over a wide frequency band and wide oblique incidence angle of a plane wave. The optimized results for different frequency bands and incidence angles show that the minimized reflection coefficients and corresponding relative permittivity are within an acceptable range for each application considered in this work.     

On decentralized stabilization of interconnected systems

A decentralized control scheme is proposed for stabilization of interconnected systems consisting of arbitrarily connected, linear, time-invariant multivariable subsystems. Sufficient conditions are given for an interconnected system to be stabilized using only local state feedback. The obtained results are illustrated by an example.     

Utilization of waste loquat (Eriobotrya Japonica Lindley) kernels as substrate for scleroglucan production by locally isolated Sclerotium rolfsii

Present study mainly focused on investigating the feasibility of waste loquat kernels as substrate in submerged culture of Sclerotium rolfsii MT-6 for scleroglucan production. Loquat kernel contained high protein (22.5%) and total carbohydrate (71.2%) contents. Dried and powdered kernels were subjected to acid hydrolysis with 2 N HCl. The obtained hydrolysate was used for the preparation of loquat kernel extract (LKE) and detoxified loquat kernel extract (DLKE). S. rolfsii MT-6 was isolated from fermented squash (Cucurbita pepo). Optimal conditions for scleroglucan production were initial pH 5.0, shaking speed 150 rpm, 28°C, and cultivation time of 72 hr. Production media prepared with DLKE or LKE gave maximum biomass concentrations of 17.06 and 16.21 g/L, and maximum scleroglucan concentrations of 12.08 and 10.53 g/L, respectively. DLKE was also favorable substrate for mycelial growth in a uniform pellet form. This is a first report on the application of waste loquat kernels as scleroglucan production substrate and on the use of a local S. rolfsii isolate for this purpose.     

3D Neutronic Analysis in MHD Calculations at ARIES-ST Fusion Reactors Systems

In this study, we developed new models for liquid wall (FW) state at ARIES-ST fusion reactor systems. ARIES-ST is a 1,000 MWe fusion reactor system based on a low aspect ratio ST plasma. In this article, we analyzed the characteristic properties of magnetohydrodynamics (MHD) and heat transfer conditions by using Monte-Carlo simulation methods (ARIES Team et al. in Fusion Eng Des 49–50:689–695, 2000; Tillack et al. in Fusion Eng Des 65:215–261, 2003) . In fusion applications, liquid metals are traditionally considered to be the best working fluids. The working liquid must be a lithium-containing medium in order to provide adequate tritium that the plasma is self-sustained and that the fusion is a renewable energy source. As for Flibe free surface flows, the MHD effects caused by interaction with the mean flow is negligible, while a fairly uniform flow of thick can be maintained throughout the reactor based on 3-D MHD calculations. In this study, neutronic parameters, that is to say, energy multiplication factor radiation, heat flux and fissile fuel breeding were researched for fusion reactor with various thorium and uranium molten salts. Sufficient tritium amount is needed for the reactor to work itself. In the tritium breeding ratio (TBR) >1.05 ARIES-ST fusion model TBR is >1.1 so that tritium self-sufficiency is maintained for DT fusion systems (Starke et al. in Fusion Energ Des 84:1794–1798, 2009; Najmabadi et al. in Fusion Energ Des 80:3–23, 2006).     

The Effect of Hydrothermal Aging on the Low-Velocity Impact Behavior of Multi-Walled Carbon Nanotubes Reinforced Carbon Fiber/Epoxy Composite Pipes

Chemical transmission lines, petroleum and natural gas lines, pressure vessels, and pipes used in thermal facilities are expected to maintain their mechanical properties for many years without being damaged and not to be corroded in working conditions. The composite materials are the right candidate for these harsh conditions due to their superior properties. Reinforcement of nanoadditives to composite materials improves both the mechanical properties and the resistance to environmental conditions, thereby increasing the lifetime. In this study, multi-walled carbon nanotube (MWCNT) reinforced [±?55°] carbon fiber/epoxy composite pipes produced with filament wound method were used. It was hydrothermally aged in 80 °C distilled water for 1, 2, 3 weeks in order to examine the effect of environmental conditions. In order to investigate its resistance against loads that may occur in working conditions, ring tensile tests (ASTM D 2290–16 procedure A), and low-velocity impact tests at 5, 10, 15 J, energy levels were carried out. The effect of hydrothermal aging on neat and MWCNT added epoxy composite had been examined by considering the aging period. Consequently, the impact resistance of neat and MWCNT added samples decreased with the aging process. Besides, tangential tensile strength loss was 17% in MWCNT reinforced sample and 13% in the neat sample.

     

Industrial wireless sensor and actuator networks in industry 4.0: Exploring requirements,protocols, and challenges—A MAC survey

The vision to connect everyday physical objects to the Internet promises to create the Internet of Things (IoT), which is expected to integrate the diverse technologies such as sensors, actuators, radio frequency identification, communication technologies, and Internet protocols. Thus, IoT promises to transfer traditional industry to advance digital industry known as the Industry 4.0. At the core of the Industry 4.0 are the wireless sensor networks (WSNs) and wireless sensor and actuator networks (WSANs) that led to the development of industrial wireless sensor networks (IWSNs) and industrial wireless sensor and actuator networks (IWSANs). These networks play a central role of connecting machines, parts, products, and humans and create a diverse set of new applications to support intelligent and autonomous decision making. The IWSAN is a promising technology for numerous industrial applications because of their several potential benefits such as simple deployment, low cost, less complexity, and mobility support. However, despite such benefits, they impose several unique challenges at different layers of the protocol stack when deploying them for various monitoring and control applications in the Industry 4.0. In this article, we explore IWSAN, its applications, requirements, challenges, and solutions in the context of industrial control applications. Our main focus is on the medium access control (MAC) layer that can be exploited to satisfy such requirements. Our discussion presents extensive background study of the MAC schemes and it reviews the MAC protocols of the existing wireless standards and technologies. A number of application‐specific MAC protocols developed to support industrial applications, which are not part of these standards, are also elaborated. We rationalize to what extent the existing standards and protocols help in solving such requirements as laid down by the Industry 4.0. In the end, we emphasize on existing challenges and present important future directions.     

The effects of tannins on adhesion strength and surface roughness of varnished wood after accelerated weathering

This study evaluated the effect of accelerated weathering on the adhesion strength and surface roughness of beech wood (Fagus orientalis) treated with mimosa and quebracho extracts and coated with polyurethane, water-based, and cellulosic varnishes. Untreated beech wood blocks and beech wood blocks treated with Tanalith-E were used as control samples. Test samples were exposed to accelerated weathering processes of 100 and 300 h. According to the test results, the mean adhesion strength of the wood samples impregnated with mimosa and quebracho tannins decreased by a maximum of 20%, while increases in the mean surface roughness (R _a) were detected. The highest adhesion strength and lowest mean surface roughness were obtained with polyurethane varnish. Moreover, the mean adhesion strength increased with the accelerated weathering up to 100 h and then decreased thereafter. As a result of the weathering process, the mean surface roughness increased and was thus negatively affected.     

Investigation of the soil amplification factor in the Adapazari region

Turkey is located on the highly active Eurasian plate. A very active strike slip fault, the North Anatolian Fault Zone (NAFZ), crosses Turkey from east to west; earthquakes occurred on this fault on August 17, 1999 (Kocaeli) and November 12, 1999 (Düzce). Regional geology and subsoil conditions can significantly change the characteristics of ground motion. For this reason, determining soil amplification during an earthquake, especially for soft soils, is a very important topic for researchers. In this study, one dimensional ground response analyses were performed for selected Adapazari sites using the August 17, 1999 Kocaeli earthquake strong ground motion record with SHAKE2000 software. Soil characteristics and depth to engineering bedrock at the selected sites are different and the observed level of structural damage at these sites during the Kocaeli earthquake was also different. Calculated soil surface response spectrums at these sites were compared with the recommended design spectra of the Turkish Earthquake Code and the Eurocode 8. According to one dimensional ground response analyses, the calculated response spectra of the selected sites exceed the recommended design spectra of the Turkish Earthquake Code and the Eurocode 8. Calculations show that higher amplification ratios occur at higher periods due to soil behaviour. Results of this study indicate that local geological conditions may amplify ground motion at some periods and, due to this amplification, the calculated response spectra may exceed the recommended design spectra. Therefore, it is clear that local site conditions must be considered for earthquake-resistant engineering designs on soft alluvial soil deposits.     

Implementing commercial information exchange: a construction supply chain case study

The concept of electronic trading (e-trading) has transformed supply chain interactions in many industries, yet little research explored its implementation by Architecture, Engineering and Construction (AEC) supply chain firms. E-trading relies on commercial information exchange by supply chain partners which is generally adopted through intermediary technology partners (Hub Providers) to facilitate the accurate and timely communication of transactional data between buyers and supplier. A case study was conducted to explore the challenges and barriers to implementation of cross-firm commercial information exchange. The study primarily involved investigation of the interfaces between software development and organizational functions assisting with the electronic exchange of commercial information (eCIX) implementation. Findings from the case study show that implementation of commercial information exchange is not an easy task with several themes of factors to be considered during delivery of such projects, namely technical, coordination, integration and organizational. The study contributes to the knowledge and deployment of e-trading solutions within the context of AEC firms, and should be of interest to the practitioners contemplating similar projects.