scholarly journals NOx Reduction Pathways during LNT Operation over Ceria Containing Catalysts: Effect of Copper Presence and Barium Content

2021 ◽  
Vol 11 (12) ◽  
pp. 5700
Author(s):  
Juan Carlos Martínez-Munuera ◽  
Javier A. Giménez-Mañogil ◽  
Roberto Matarrese ◽  
Lidia Castoldi ◽  
Avelina García-García
Keyword(s):  
Noble Metals ◽  
Chemical Engineering ◽  
Materials Science ◽  
Control Strategies ◽  
Nox Reduction ◽  
Product Formation ◽  
Reduction Step ◽  
The Rich ◽  
Effect Of Copper ◽  
The Impact

Ceria-based catalysts, with Cu in substitution of noble metals, were studied in a vertical microreactor system under isothermal conditions, where NOx was previously stored, followed by the reduction step conducted under H2. The possible remaining ad-NOx species after the reduction stage, were investigated by Temperature Programmed Desorption in He. In situ DRIFTS was used as a complementary technique for the analysis of the surface species formation/transformation on the catalysts’ surface. Catalysts containing both Ba and Cu were found to be selective in the NOx reduction, producing N2 and minor amounts of NH3 during the reduction step, as well as NO. The different ceria-based formulations (containing copper and/or barium) were prepared and tested at two different temperatures in the NOx reduction (NSR) processes. Their catalytic activities were analyzed in terms of their compositions and have been useful in the elucidation of the possible origin and relevant pathways for NOx reduction product formation, which seems to involve the oxygen vacancies of the ceria-based materials (whose generation seems to be promoted by copper) during the rich step. The scope of this work involves an interdisciplinary study of the impact that catalysts’ formulations (noble metal-free) have on their LNT performance under simulated conditions, thus covering aspects of Materials Science and Chemical Engineering in a highly applied context, related to the development of control strategies for hybrid powertrains and/or the reduction of the impact of cold-start emissions.

Modeling of a Partial-Flow, Diesel, Lean NOx Trap Systems

2005 ◽  
Author(s):  
Shawn Midlam-Mohler ◽  
Yann Guezennec
Keyword(s):  
Diesel Fuel ◽  
Control Strategies ◽  
Nox Reduction ◽  
Lean Nox Trap ◽  
Component Level ◽  
Lean Nox ◽  
Catalyst Temperature ◽  
The Rich ◽  
And Control ◽  
Regeneration Systems

Lean NOx Traps (LNTs) have shown promise for Diesel applications; however, production implementation in vehicles poses a number of challenges. Much of the literature reports on LNT systems in which the catalyst always receives the full flow of exhaust from the engine, referred here as full-flow regeneration systems. Another implementation of the LNT is one in which the exhaust can be partially or fully diverted from the catalyst to allow local introduction of the necessary reductants for regeneration. The physical aspects of one such system, as well as a control-oriented model are presented with experimental validation. In the system described here, the exhaust flow is diverted around the catalyst during regenerations. In the low exhaust flow through the catalyst, reductant is added (Diesel fuel typically) which provides the rich conditions for regenerating the trap. This allows the engine to continue to run in normal lean mode, which overcomes one of the major challenges for full-flow regeneration systems. Successful regeneration with liquid Diesel fuel is strongly dependent on catalyst temperature, which is addressed by proper thermal management of the system through the addition of fuel prior to regeneration. In this paper, both component level and vehicle level simulations are presented in terms of fuel economy versus NOx reduction. Several different system configurations and control strategies are compared.

The Consequences of Excessive Chemicalization on Fruits Quality

2018 ◽  
Vol 69 (6) ◽  
pp. 1303-1308 ◽  
Author(s):  
Manuel Alexandru Gitea ◽  
Simona Bungau ◽  
Daniela Gitea ◽  
Lavinia Purza ◽  
Sebastian Nemeth ◽  
...  
Keyword(s):  
Environmental Protection ◽  
Pesticide Residues ◽  
Chemical Engineering ◽  
Agricultural Productivity ◽  
Fruit Trees ◽  
Pesticide Treatment ◽  
Intensive Intervention ◽  
Optimal Efficiency ◽  
The Impact ◽  
Intensive System

Chemistry in agriculture has been considered for several decades a formula synonymous with progress and development, as chemical engineering, mechanization, irrigation, modern agro-technical processes have contributed to a substantial increase in production. At present, the use of pesticides to increase agricultural productivity is considered to be a global hazard to the environment. This study examines changes in tree tolerance for major diseases and pests, disease and pest behavior, and the changes that occur in the recommended pesticide treatment. The researches were carried out on different species of fruit trees (apple, plum, and almond), cultivated in an intensive system, in five orchards located in Bihor county. The behavior of each species, as well as the behavior of different varieties with respect to tolerance to major diseases and pests, have been observed over the last 5 years (2013-2017). In addition, pesticide residues were monitored from all crops of apple, plum and almond. During 2015-2017, from March to May, the diseases were more virulent, requiring intensive intervention with systemic and contact fungicide combinations to achieve optimal efficiency; this fact has been correlated with the increase in the number of samples containing pesticide residues. This perspective allows an ecological remodeling of current progress in orchard development, including all aspects of environmental protection and the impact on population2 s health.

scholarly journals Power Hardware-in-the-Loop-Based Performance Analysis of Different Converter Controllers for Fast Active Power Regulation in Low-Inertia Power Systems

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3274
Author(s):  
Jose Rueda Torres ◽  
Zameer Ahmad ◽  
Nidarshan Veera Kumar ◽  
Elyas Rakhshani ◽  
Ebrahim Adabi ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Power Systems ◽  
Real Time ◽  
Control Strategies ◽  
Active Power ◽  
Power Electronic ◽  
Hardware In The Loop ◽  
Digital Controllers ◽  
Power Regulation ◽  
The Impact

Future electrical power systems will be dominated by power electronic converters, which are deployed for the integration of renewable power plants, responsive demand, and different types of storage systems. The stability of such systems will strongly depend on the control strategies attached to the converters. In this context, laboratory-scale setups are becoming the key tools for prototyping and evaluating the performance and robustness of different converter technologies and control strategies. The performance evaluation of control strategies for dynamic frequency support using fast active power regulation (FAPR) requires the urgent development of a suitable power hardware-in-the-loop (PHIL) setup. In this paper, the most prominent emerging types of FAPR are selected and studied: droop-based FAPR, droop derivative-based FAPR, and virtual synchronous power (VSP)-based FAPR. A novel setup for PHIL-based performance evaluation of these strategies is proposed. The setup combines the advanced modeling and simulation functions of a real-time digital simulation platform (RTDS), an external programmable unit to implement the studied FAPR control strategies as digital controllers, and actual hardware. The hardware setup consists of a grid emulator to recreate the dynamic response as seen from the interface bus of the grid side converter of a power electronic-interfaced device (e.g., type-IV wind turbines), and a mockup voltage source converter (VSC, i.e., a device under test (DUT)). The DUT is virtually interfaced to one high-voltage bus of the electromagnetic transient (EMT) representation of a variant of the IEEE 9 bus test system, which has been modified to consider an operating condition with 52% of the total supply provided by wind power generation. The selected and programmed FAPR strategies are applied to the DUT, with the ultimate goal of ascertaining its feasibility and effectiveness with respect to the pure software-based EMT representation performed in real time. Particularly, the time-varying response of the active power injection by each FAPR control strategy and the impact on the instantaneous frequency excursions occurring in the frequency containment periods are analyzed. The performed tests show the degree of improvements on both the rate-of-change-of-frequency (RoCoF) and the maximum frequency excursion (e.g., nadir).

scholarly journals Estimating asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan: a mathematical modeling study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xi Huo ◽  
Jing Chen ◽  
Shigui Ruan
Keyword(s):  
Disease Transmission ◽  
Large Scale ◽  
Transmission Rate ◽  
Control Strategies ◽  
Herd Immunity ◽  
Antibody Prevalence ◽  
Screening Process ◽  
Vaccination Programs ◽  
Prevalence Level ◽  
The Impact

Abstract Background The COVID-19 outbreak in Wuhan started in December 2019 and was under control by the end of March 2020 with a total of 50,006 confirmed cases by the implementation of a series of nonpharmaceutical interventions (NPIs) including unprecedented lockdown of the city. This study analyzes the complete outbreak data from Wuhan, assesses the impact of these public health interventions, and estimates the asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan. Methods By taking different stages of the outbreak into account, we developed a time-dependent compartmental model to describe the dynamics of disease transmission and case detection and reporting. Model coefficients were parameterized by using the reported cases and following key events and escalated control strategies. Then the model was used to calibrate the complete outbreak data by using the Monte Carlo Markov Chain (MCMC) method. Finally we used the model to estimate asymptomatic and undetected cases and approximate the overall antibody prevalence level. Results We found that the transmission rate between Jan 24 and Feb 1, 2020, was twice as large as that before the lockdown on Jan 23 and 67.6% (95% CI [0.584,0.759]) of detectable infections occurred during this period. Based on the reported estimates that around 20% of infections were asymptomatic and their transmission ability was about 70% of symptomatic ones, we estimated that there were about 14,448 asymptomatic and undetected cases (95% CI [12,364,23,254]), which yields an estimate of a total of 64,454 infected cases (95% CI [62,370,73,260]), and the overall antibody prevalence level in the population of Wuhan was 0.745% (95% CI [0.693%,0.814%]) by March 31, 2020. Conclusions We conclude that the control of the COVID-19 outbreak in Wuhan was achieved via the enforcement of a combination of multiple NPIs: the lockdown on Jan 23, the stay-at-home order on Feb 2, the massive isolation of all symptomatic individuals via newly constructed special shelter hospitals on Feb 6, and the large scale screening process on Feb 18. Our results indicate that the population in Wuhan is far away from establishing herd immunity and provide insights for other affected countries and regions in designing control strategies and planing vaccination programs.

The effects of debt restructurings on income inequality in the developing world

2021 ◽  
pp. 135406612110014
Author(s):  
Glen Biglaiser ◽  
Ronald J. McGauvran
Keyword(s):  
Developing Countries ◽  
Panel Data ◽  
Income Inequality ◽  
Income Distribution ◽  
Government Spending ◽  
Tax Reform ◽  
Social Spending ◽  
The Poor ◽  
The Rich ◽  
The Impact

Developing countries, saddled with debts, often prefer investors absorb losses through debt restructurings. By not making full repayments, debtor governments could increase social spending, serving poorer constituents, and, in turn, lowering income inequality. Alternatively, debtor governments could reduce taxes and cut government spending, bolstering the assets of the rich at the expense of the poor. Using panel data for 71 developing countries from 1986 to 2016, we assess the effects of debt restructurings on societal income distribution. Specifically, we study the impact of debt restructurings on social spending, tax reform, and income inequality. We find that countries receiving debt restructurings tend to use their newly acquired economic flexibility to reduce taxes and lower social spending, worsening income inequality. The results are also robust to different model specifications. Our study contributes to the globalization and the poor debate, suggesting the economic harm caused to the less well-off following debt restructurings.

The impact of preozonation and biodegradation on disinfection by-product formation

1992 ◽  
Vol 26 (9) ◽  
pp. 1217-1227 ◽  
Author(s):  
H SHUKAIRY ◽  
R SCOTTSUMMERS
Keyword(s):  
Product Formation ◽  
The Impact

scholarly journals Prevalence of mastitis in Nigerian livestock: a Review

2020 ◽  
Vol 1 (1) ◽  
pp. 20-29
Author(s):  
Hussaini Ojagefu Adamu ◽  
Rahimat Oshuwa Hussaini ◽  
Cedric Obasuyi ◽  
Linus Irefo Anagha ◽  
Gabriel Oscy Okoduwa
Keyword(s):  
Control Strategies ◽  
Dairy Farms ◽  
Livestock Production ◽  
Sub Saharan Africa ◽  
Economic Losses ◽  
Ecological Development ◽  
Management Plans ◽  
Sub Saharan ◽  
Control And Management ◽  
The Impact

AbstractMastitis is a disease of livestock that directly impede livestock production and thus hindering the socio-ecological development of sub-Saharan Africa. Studies have estimated the prevalence of this disease in 30% of Africa countries, with Ethiopia having the highest prevalence. The coverage is low, despite the wide livestock and dairy farms distribution in Africa. Furthermore, estimated economic losses due to the impact of mastitis are lacking in Nigeria. The disease is endemic in Nigeria as indicated by the available data and there are no proposed management plans or control strategies. This review is thus presented to serve as a wakeup call to all parties involved to intensify efforts towards the diagnosis, control, and management of the disease in Nigeria.

scholarly journals Rethinking success, integrity, and culture in research (part 2) — a multi-actor qualitative study on problems of science

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Noémie Aubert Bonn ◽  
Wim Pinxten
Keyword(s):  
Research Misconduct ◽  
Research Integrity ◽  
Research Culture ◽  
Structured Interviews ◽  
Community Members ◽  
Questionable Research Practices ◽  
Research Problems ◽  
The Rich ◽  
Research Students ◽  
The Impact

Abstract Background Research misconduct and questionable research practices have been the subject of increasing attention in the past few years. But despite the rich body of research available, few empirical works also include the perspectives of non-researcher stakeholders. Methods We conducted semi-structured interviews and focus groups with policy makers, funders, institution leaders, editors or publishers, research integrity office members, research integrity community members, laboratory technicians, researchers, research students, and former-researchers who changed career to inquire on the topics of success, integrity, and responsibilities in science. We used the Flemish biomedical landscape as a baseline to be able to grasp the views of interacting and complementary actors in a system setting. Results Given the breadth of our results, we divided our findings in a two-paper series with the current paper focusing on the problems that affect the integrity and research culture. We first found that different actors have different perspectives on the problems that affect the integrity and culture of research. Problems were either linked to personalities and attitudes, or to the climates in which researchers operate. Elements that were described as essential for success (in the associate paper) were often thought to accentuate the problems of research climates by disrupting research culture and research integrity. Even though all participants agreed that current research climates need to be addressed, participants generally did not feel responsible nor capable of initiating change. Instead, respondents revealed a circle of blame and mistrust between actor groups. Conclusions Our findings resonate with recent debates, and extrapolate a few action points which might help advance the discussion. First, the research integrity debate must revisit and tackle the way in which researchers are assessed. Second, approaches to promote better science need to address the impact that research climates have on research integrity and research culture rather than to capitalize on individual researchers’ compliance. Finally, inter-actor dialogues and shared decision making must be given priority to ensure that the perspectives of the full research system are captured. Understanding the relations and interdependency between these perspectives is key to be able to address the problems of science. Study registration https://osf.io/33v3m

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