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91.
As low-power wide-area network (LPWAN) end devices (EDs) are deployed in massive scale, their economic and environmental costs of operation are becoming too significant to ignore and too difficult to estimate. While LPWAN architectures and protocols are designed to primarily save energy, this study shows that energy saving does not necessarily lead to lower cost or environmental footprint of the network. Accordingly, a theoretical framework is proposed to estimate the operational expenditure (OpEx) and environmental footprint of LPWAN EDs. An extended constrained optimization model is provided for the ED link assignment to gateways (GWs) based on heterogeneous ED configurations and hardware specifications. Based on the models, a simulation framework is developed which demonstrates that OpEx, energy consumption, and environmental footprint can be in conflict with each other as constrained optimization objectives. We demonstrate different ways to achieve compromises in each dimension for overall improved network performance. 相似文献
92.
Maryam Arsalanfar;Azita Nouri;Majid Abdouss;Esmaeil Rezazadeh; 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2024,99(1):133-148
Light olefins production greatly influenced by the process conditions. In the present work Al2O3 supported Co-Ni nanocatalysts were evaluated for production of light olefins. Incipient wetness impregnation procedure was used for catalyst synthesis. Catalysts were characterized for determining the physicochemical properties using various techniques of XRD, SEM, EDS, H2-TPR, TPD, TEM, XPS, TGA, DSC, FT-IR, and BET. The influence of process conditions (Pressure, Temperature and H2/CO inlet feed molar ratio) was investigated on the catalytic performance of Co-Ni/γAl2O3 nanocatalyst toward lower olefins. Temperature, pressure, and feed ratio factors were changed in wide ranges of 250–450 °C, 1–12 bar, and 1–4 respectively. The Response Surface Methodology (RSM) method was employed for modeling and optimization. 相似文献
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Mina Shiran Chaharsoughi Dan Zhao Xavier Crispin Simone Fabiano Magnus P. Jonsson 《Advanced functional materials》2019,29(28)
Sensors for monitoring temperature, heat flux, and thermal radiation are essential for applications such as electronic skin. While pyroelectric and thermoelectric effects are suitable candidates as functional elements in such devices, both concepts show individual drawbacks in terms of zero equilibrium signals for pyroelectric materials and small or slow response of thermoelectric materials. Here, these drawbacks are overcome by introducing the concept of thermodiffusion‐assisted pyroelectrics, which combines and enhances the performance of pyroelectric and ionic thermoelectric materials. The presented integrated concept provides both rapid initial response upon heating and stable synergistically enhanced signals upon prolonged exposure to heat stimuli. Likewise, incorporation of plasmonic metasurfaces enables the concept to provide both rapid and stable signals for radiation‐induced heating. The performance of the concept and its working mechanism can be explained by ion–electron interactions at the interface between the pyroelectric and ionic thermoelectric materials. 相似文献
95.
Motahareh Hosseini Masoud Esfandeh Mohammad Razavi‐Nouri Amir Masoud Rezadoust 《Polymer Composites》2019,40(7):2700-2711
The aim of this work was to study the effect of carboxyl‐terminated acrylonitrile butadiene (CTBN) liquid rubber and alumina nanoparticles (Al2O3) on the fracture toughness of an epoxy resin. Hybrid nanocomposite samples were prepared by the inclusion of the optimum concentration of CTBN (15 phr) and 0–10 phr Al2O3 into the epoxy matrix. Samples were examined using Fourier transform infrared spectroscopy, scanning electron microscopy, and fracture toughness test. Fractal dimension values were also estimated from the edge of the fracture surfaces for the hybrid samples. The maximum value of critical stress intensity factor, K IC , was found for the non‐hybrid sample containing 15 phr CTBN and the G IC values showed an increasing trend as it was expected from the increase in K IC values and decrease in Young's modulus. The maximum K IC for the hybrid samples was obtained for the one containing 7 phr Al2O3 and an almost similar trend was observed for G IC , accompanied with the significant changes in the fracture surface morphology. These were consistent with the fractal dimension results, where the sample containing 7 phr Al2O3 exhibited the maximum roughness. Therefore, the hybrid system of epoxy/CTBN (15 phr)/Al2O3 (7 phr) was found to be the optimum formulation. POLYM. COMPOS., 40:2700–2711, 2019. © 2018 Society of Plastics Engineers 相似文献
96.
The effects of a new latent accelerator and those of two common accelerators of 1-methyl imidazole and 2,4,6-tris(dimethylaminomethyl)phenol (DMP) have been studied in relation to the properties of dicyandiamide (dicy) cured epoxy resin and its prepregs with unidirectional carbon fiber. The new prepared accelerator is an adduct based on DMP (A_DMP). The results showed that the curing behavior of epoxy/dicy did not change when the appropriate amount of new accelerator was used. The amount of 5 phr of new latent accelerator is equal to the amount of 0.6 phr of DMP accelerator and by increasing the amount of new accelerator, the curing reaction of epoxy/dicy increased significantly. Viscosity build-up results and gel time measurements showed the high pot-life of resin system (epoxy/Dicy/A_DMP) and the high shelf-life of their prepreg. The results showed that the lap shear strength of sample containing 5 phr of the new accelerator (A_DMP5) was increased by 127% in comparison to the sample containing 0.6 phr of DMP. Transverse tensile strength and strain-at-break were increased by 27% and 31.7%, respectively. Transverse flexural strength, flexural strain-at-break and flexural modulus increased by 52%, 11% and 60%, respectively. On the other hand, fracture toughness and fracture energy increased significantly by 214% and 700%, respectively. This increase in mechanical properties was due to the bulkiness of the new latent accelerator acting as a toughening agent and also the good adhesion of fiber to the matrix as revealed by scanning electron microscopy.
相似文献97.
Rik Bhnemann Michael Pantic Marija Popovi&#x; Dominik Schindler Marco Tranzatto Mina Kamel Marius Grimm Jakob Widauer Roland Siegwart Juan Nieto 《野外机器人技术杂志》2019,36(1):78-103
This study describes the hardware and software systems of the Micro Aerial Vehicle (MAV) platforms used by the ETH Zurich team in the 2017 Mohamed Bin Zayed International Robotics Challenge (MBZIRC). The aim was to develop robust outdoor platforms with the autonomous capabilities required for the competition, by applying and integrating knowledge from various fields, including computer vision, sensor fusion, optimal control, and probabilistic robotics. This paper presents the major components and structures of the system architectures and reports on experimental findings for the MAV‐based challenges in the competition. Main highlights include securing the second place both in the individual search, pick, and place the task of Challenge 3 and the Grand Challenge, with autonomous landing executed in less than 1 min and a visual servoing success rate of over for object pickups. 相似文献
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100.
Hyun Goo Ji Pablo Solís‐Fernndez Daisuke Yoshimura Mina Maruyama Takahiko Endo Yasumitsu Miyata Susumu Okada Hiroki Ago 《Advanced materials (Deerfield Beach, Fla.)》2019,31(42)
Monolayers of transition metal dichalcogenides (TMDCs) have attracted a great interest for post‐silicon electronics and photonics due to their high carrier mobility, tunable bandgap, and atom‐thick 2D structure. With the analogy to conventional silicon electronics, establishing a method to convert TMDC to p‐ and n‐type semiconductors is essential for various device applications, such as complementary metal‐oxide‐semiconductor (CMOS) circuits and photovoltaics. Here, a successful control of the electrical polarity of monolayer WSe2 is demonstrated by chemical doping. Two different molecules, 4‐nitrobenzenediazonium tetrafluoroborate and diethylenetriamine, are utilized to convert ambipolar WSe2 field‐effect transistors (FETs) to p‐ and n‐type, respectively. Moreover, the chemically doped WSe2 show increased effective carrier mobilities of 82 and 25 cm2 V?1s?1 for holes and electrons, respectively, which are much higher than those of the pristine WSe2. The doping effects are studied by photoluminescence, Raman, X‐ray photoelectron spectroscopy, and density functional theory. Chemically tuned WSe2 FETs are integrated into CMOS inverters, exhibiting extremely low power consumption ( ≈ 0.17 nW). Furthermore, a p‐n junction within single WSe2 grain is realized via spatially controlled chemical doping. The chemical doping method for controlling the transport properties of WSe2 will contribute to the development of TMDC‐based advanced electronics. 相似文献