Hasil untuk "Fuel"

S. Santra

A. Jacobson

Qingfeng Li, J. Jensen, R. Savinell et al.

Abstract To achieve high temperature operation of proton exchange membrane fuel cells (PEMFC), preferably under ambient pressure, acid–base polymer membranes represent an effective approach. The phosphoric acid-doped polybenzimidazole membrane seems so far the most successful system in the field. It has in recent years motivated extensive research activities with great progress. This treatise is devoted to updating the development, covering polymer synthesis, membrane casting, physicochemical characterizations and fuel cell technologies. To optimize the membrane properties, high molecular weight polymers with synthetically modified or N-substituted structures have been synthesized. Techniques for membrane casting from organic solutions and directly from acid solutions have been developed. Ionic and covalent cross-linking as well as inorganic–organic composites has been explored. Membrane characterizations have been made including spectroscopy, water uptake and acid doping, thermal and oxidative stability, conductivity, electro-osmotic water drag, methanol crossover, solubility and permeability of gases, and oxygen reduction kinetics. Related fuel cell technologies such as electrode and MEA fabrication have been developed and high temperature PEMFC has been successfully demonstrated at temperatures of up to 200 °C under ambient pressure. No gas humidification is mandatory, which enables the elimination of the complicated humidification system, compared with Nafion cells. Other operating features of the PBI cell include easy control of air flow rate, cell temperature and cooling. The PBI cell operating at above 150 °C can tolerate up to 1% CO and 10 ppm SO 2 in the fuel stream, allowing for simplification of the fuel processing system and possible integration of the fuel cell stack with fuel processing units. Long-term durability with a degradation rate of 5 μV h −1 has been achieved under continuous operation with hydrogen and air at 150–160 °C. With load or thermal cycling, a performance loss of 300 μV per cycle or 40 μV h −1 per operating hour was observed. Further improvement should be done by, e.g. optimizing the thermal and chemical stability of the polymer, acid–base interaction and acid management, activity and stability of catalyst and more importantly the catalyst support, as well as the integral interface between electrode and membrane.

S. Bonjour, Heather Adair-Rohani, J. Wolf et al.

Background: Exposure to household air pollution from cooking with solid fuels in simple stoves is a major health risk. Modeling reliable estimates of solid fuel use is needed for monitoring trends and informing policy. Objectives: In order to revise the disease burden attributed to household air pollution for the Global Burden of Disease 2010 project and for international reporting purposes, we estimated annual trends in the world population using solid fuels. Methods: We developed a multilevel model based on national survey data on primary cooking fuel. Results: The proportion of households relying mainly on solid fuels for cooking has decreased from 62% (95% CI: 58, 66%) to 41% (95% CI: 37, 44%) between 1980 and 2010. Yet because of population growth, the actual number of persons exposed has remained stable at around 2.8 billion during three decades. Solid fuel use is most prevalent in Africa and Southeast Asia where > 60% of households cook with solid fuels. In other regions, primary solid fuel use ranges from 46% in the Western Pacific, to 35% in the Eastern Mediterranean and < 20% in the Americas and Europe. Conclusion: Multilevel modeling is a suitable technique for deriving reliable solid-fuel use estimates. Worldwide, the proportion of households cooking mainly with solid fuels is decreasing. The absolute number of persons using solid fuels, however, has remained steady globally and is increasing in some regions. Surveys require enhancement to better capture the health implications of new technologies and multiple fuel use.

D. Brett, A. Atkinson, N. Brandon et al.

O. Hurricane, D. Callahan, D. Casey et al.

A. Appleby, F. R. Foulkes

S. Singhal

A. Atkinson, S. Barnett, R. Gorte et al.

B. Logan, J. Regan

G. Cahill

L. Carrette, K. Friedrich, U. Stimming

C. Yin, Jinyue Yan

F. Perera

Background: Approaches to estimating and addressing the risk to children from fossil fuel combustion have been fragmented, tending to focus either on the toxic air emissions or on climate change. Yet developing children, and especially poor children, now bear a disproportionate burden of disease from both environmental pollution and climate change due to fossil fuel combustion. Objective: This commentary summarizes the robust scientific evidence regarding the multiple current and projected health impacts of fossil fuel combustion on the young to make the case for a holistic, child-centered energy and climate policy that addresses the full array of physical and psychosocial stressors resulting from fossil fuel pollution. Discussion: The data summarized here show that by sharply reducing our dependence on fossil fuels we would achieve highly significant health and economic benefits for our children and their future. These benefits would occur immediately and also play out over the life course and potentially across generations. Conclusion: Going beyond the powerful scientific and economic arguments for urgent action to reduce the burning of fossil fuels is the strong moral imperative to protect our most vulnerable populations. Citation: Perera FP. 2017. Multiple threats to child health from fossil fuel combustion: impacts of air pollution and climate change. Environ Health Perspect 125:141–148; http://dx.doi.org/10.1289/EHP299

Jonathon Hirschi

Fuel moisture content (FMC) is a key predictor for wildfire rate of spread (ROS). Machine learning models of FMC are being used more in recent years, augmenting or replacing traditional physics-based approaches. Wildfire rate of spread (ROS) has a highly nonlinear relationship with FMC, where small differences in dry fuels lead to large differences in ROS. In this study, custom loss functions that place more weight on dry fuels were examined with a variety of machine learning models of FMC. The models were evaluated with a spatiotemporal cross-validation procedure to examine whether the custom loss functions led to more accurate forecasts of ROS. Results show that the custom loss functions improved accuracy for ROS forecasts by a small amount. Further research would be needed to establish whether the improvement in ROS forecasts leads to more accurate real-time wildfire simulations.

MD Zobaer Hossain Bhuiyan, Abir Bin Faruque, Mahtab Newaz et al.

This paper presents the design and development of a low-cost fuel dispensing system prototype based on the STM32 microcontroller and L298N motor driver. The system aims to provide an affordable and scalable solution for fuel delivery in remote or small-scale environments where conventional, high-cost systems are not feasible. The core control unit is built using an STM32 microcontroller, which manages user input through a 4x4 matrix keypad and displays operational data on a 16x4 LCD screen via I2C communication. A 12V DC pump motor is used to simulate the fuel dispensing mechanism, precisely controlled via the dual H-bridge L298N motor driver. The system is powered by a 11.1V battery and is designed for ease of deployment and portability. The keypad allows users to input the desired fuel amount, while the system ensures accurate motor runtime corresponding to the volume to be dispensed. This project demonstrates how embedded systems can be leveraged to build cost-effective, user-friendly, and energy-efficient solutions. The proposed design can be further enhanced with flow sensors, GSM connectivity, RFID cards, and payment integration for real-world applications in fuel stations or agricultural use.

Seyed Mehdi Rakhtala, Roja Eini

In this paper, a nonlinear six order model is proposed for a proton exchange membrane fuel cell (PEMFC) as a control-oriented electrochemical model. Its validation is performed on a specific single cell PEMFC with effective dimension of 5 cm5 cm. This model is described in the nonlinear state space form with 6 state variables. Load current and DC voltage are considered as measurable disturbance and control input respectively. Besides, the model includes fuel cell stack and its auxiliary components as well. In this survey, a nonlinear state space representation is derived by arranging nonlinear equations and combining them with auxiliary components model. The proposed model can be successfully used to design nonlinear controller and nonlinear observer systems. The analyzed PEMFC system consists of air compressor motor dynamic equations, air and fuel supply subsystems, a perfect air humidifier and a fuel cell stack. An experimentally validated nonlinear model that reproduces the most typical features of a laboratory PEMFC system is presented. This model is derived based on physics law in stack, including system gases dynamics. The objective of this paper is to introduce a fully analytical model which has been fully validated on a fuel cell system and its auxiliary components. The proposed method can be used as a general modeling guideline for control-oriented purposes. Moreover, it can be successfully implemented in composing a dynamic subsystem, like hydrogen subsystem, as part of the whole nonlinear model.

Shaoming Han, Cheng Qian, Nawal Abdalla Adam et al.

This study examines the impact of financial inclusion on bank stability across 36 emerging economies, utilizing bank-level data from over 1,500 commercial banks spanning the period 2004 to 2023. Despite the recognized benefits of financial inclusion, its influence on banking stability remains complex and context dependent. The research employs advanced econometric methodologies, including fixed-effects models, Driscoll-Kraay standard errors to address heteroskedasticity and cross-sectional dependence, and system Generalized Method of Moments (GMM) estimation to control for endogeneity and dynamic effects. The findings reveal that financial inclusion generally enhances bank stability and positively influences operational efficiency and funding stability. However, during periods of lax financial regulations or excessive government intervention, banks may engage in riskier behaviors, potentially undermining stability. Key results indicate that (1) robust economic growth and stable policy environments amplify the positive effects of financial inclusion on bank stability, (2) excessive government control may foster risk-taking behaviors, (3) strong financial conditions mitigate adverse impacts, (4) financial inclusion improves risk management and operational efficiency, and (5) effective regulatory frameworks are pivotal in leveraging financial inclusion for sound banking operations. These insights suggest that policymakers in emerging markets should carefully balance the promotion of financial inclusion with safeguards that maintain financial stability.

Kwan‐Soo Lee, J. Spendelow, Y. Choe et al.

Min Zhou, Hui Jin, Wenshuo Wang