To build a secure wireless networking system, it is essential that the cryptographic key is known only to the two (or more) communicating parties. Existing key extraction schemes put the devices into physical proximity and utilize the common inherent randomness between the devices to agree on a secret key, but they often rely on specialized hardware (e.g., the specific wireless NIC model) and have low bit rates. In this article, we seek a key extraction approach that only leverages off-the-shelf mobile devices, while achieving significantly higher key generation efficiency. The core idea of our approach is to exploit the fast varying inaudible acoustic channel as the common random source for key generation and wireless parallel communication for exchanging reconciliation information to improve the key generation rate. We have carefully studied and validated the feasibility of our approach through both theoretical analysis and a variety of measurements. We implement our approach on different mobile devices and conduct extensive experiments in different real scenarios. The experiment results show that our approach achieves high efficiency and satisfactory robustness. Compared with state-of-the-art methods, our approach improves the key generation rate by 38.46% and reduces the bit mismatch ratio by 42.34%.
Firebrand spotting is a potential threat to people and infrastructure, which is difficult to predict and becomes more significant when the size of a fire and intensity increases. To conduct realistic physics-based modeling with firebrand transport, the firebrand generation data such as numbers, size, and shape of the firebrands are needed. Broadly, the firebrand generation depends on atmospheric conditions, wind velocity and vegetation species. However, there is no experimental study that has considered all these factors although they are available separately in some experimental studies. Moreover, the experimental studies have firebrand collection data, not generation data. In this study, we have conducted a series of physics-based simulations on a trial-and-error basis to reproduce the experimental collection data, which is called an inverse analysis. Once the generation data was determined from the simulation, we applied the interpolation technique to calibrate the effects of wind velocity, relative humidity, and vegetation species. First, we simulated Douglas-fir (Pseudotsuga menziesii) tree-burning and quantified firebrand generation against the tree burning experiment conducted at the National Institute of Standards and Technology (NIST). Then, we applied the same technique to a prescribed forest fire experiment conducted in the Pinelands National Reserve (PNR) of New Jersey, the USA. The simulations were conducted with the experimental data of fuel load, humidity, temperature, and wind velocity to ensure that the field conditions are replicated in the experiments. The firebrand generation rate was found to be 3.22 pcs/MW/s (pcs-number of firebrands pieces) from the single tree burning and 4.18 pcs/MW/s in the forest fire model. This finding was complemented with the effects of wind, vegetation type, and fuel moisture content to quantify the firebrand generation rate.
An attempt has been taken in this work to effectively implement the combination of GSA and PSO (hGSA-PSO) technique towards AGC in two-area inter-connected power systems with generation rate constraint (GRC) is considered. For the design and analysis, a initial attempt has been taken to optimize parameters of proportional-integral-derivative (PID) controller in two area non-reheat thermal power system employing GSA and hGSA-PSO algorithm with ITAE objective function. A sensitivity studies carried out for the robustness of the system by changing the operating condition and variation of the parameter and generation rate constant (GRC= ±0.05 and ±0.025) is considered. The performances of the proposed controller has been evaluated with those of some previously published optimization techniques such as GA and BOFA based optimized controller parameters for the same power system. This study of the present work is extended to two area multi sources power system to test the robustness analysis of the system by comparing the hGSA-PSO optimized to PI controller with same structure of system by selecting with and without GRC for showing the dynamic performance analysis of the system in term of settling time and overshoot.
A hydrophobic core–shell architecture was constructed to control local H2O availability on the surface of the copper-based materials, which could provide a maximum generation rate of −434 mA cm−2 towards CH4.
The hot electrons produced by surface plasmon resonance (SPR) effect of plasmonic metal offer an efficient and sustainable strategy for traditional catalysis. However, the low generation rate and easy recombination...
The studies on the solid waste generation and characterization with their relationships with different determinants are limited in Nepal which helps in the implementation of the solid waste management approach. This study is focused on the quantification of the municipal solid waste (MSW) generation rate and its characterization in the Baglung Municipality, Nepal. Factors affecting MSW generation with perceptions towards the MSW management were also evaluated through household survey. The study was carried out in the month of January 2021 in four wards of urban zone in the municipality. The average waste generation rate in 188 households (HHs), 20 institutions, and 20 commercial sites were 0.43 kg/c/d, 0.83 kg/institute/day and 2.75 kg/commercial site/day, respectively. The largest component, which accounted for about 74% household waste, 75% institutional waste and 52% commercial waste composed of organic waste. The analysis of variance (ANOVA) indicates a significant variation in between MSW generation rate with respect to household size and type of days. Regarding affordability of MSW management, most of the households can be able to afford service fee ranged from US$ 0.5 to 1.0 (55.38%). Most of the households dispose of solid waste in the municipal vehicle. From this study, the residents of the municipality are suggested to prepare compost manure at the source for the minimization of waste volume to be transported and disposed of. Higher production of recyclable MSW depicts there is a possibility of revenue generation and importance of MSW management in community mobilization in the municipality.
The exothermic reactor for ammonia synthesis is a primary device determining the performance of the energy storage system. The Braun-type ammonia synthesis reactor is used as the exothermic reactor to improve the heat release rate. Due to the entirely different usage scenarios and design objectives, its parameters need to be redesigned and optimized. Based on finite-time thermodynamics, a one-dimensional model is established to analyze the effects of inlet gas molar flow rate, hydrogen–nitrogen ratio, reactor length and inlet temperature on the total entropy generation rate and the total exothermic rate of the reactor. It’s found that the total exothermic rate mainly depends on the inlet molar flow rate. Furthermore, considering the minimum total entropy generation rate and maximum total exothermic rate, the NSGA-II algorithm is applied to optimize seven reactor parameters including the inlet molar flow rate, lengths and temperatures of the three reactors. Lastly, the optimized reactor is obtained from the Pareto front using three fuzzy decision methods and deviation index. Compared with the reference reactor, the total exothermic rate of the optimized reactor is improved by 12.6% while the total entropy generation rate is reduced by 3.4%. The results in this paper can provide some guidance for the optimal design and application of exothermic reactors in practical engineering.