Sodium silicate mediated response of antioxidative defense system in Lycopersicon esculentum mill. under water stress

The present study was designed to study the effect of water stress on Lycopersicon esculentum Mill. and role of sodium silicate in the protection of tomato plants under water deficit condition.Different biochemical parameters such as photosynthetic pigments, protein, sugar, MDA content, proline, nitrate reductase activity and activities of antioxidant enzymes (SOD, CAT, APX and POX) were examined in tomato leaves at 40 and 60 DAS by the standard methods. The lycopene and β-carotene contentsin tomato fruits were also analyzed at 60, 65 and 70 DAS.Water stress significantly decreased relative water content (RWC), pigment content, sugar and protein contents in tomato leaves at 60 DAS but the accumulation of proline was stimulated in tomato leaves under water deficit condition. The activities of antioxidant enzymes such as SOD, CAT, APX and POX were significantly increased under (3d and 6d) water stress condition at 60 DAS.This study offers first hand information on the water stress-induced oxidative stress in Lycopersicon esculentumand development of antioxidative defense system against drought.The results obtained clearly indicated the positive impact of sodium silicate in protection of tomato plants under water deficit condition

Performance assessment of a boundary layer ingesting distributed propulsion system at off-design

As research on boundary layer ingesting aircraft concepts progresses, it becomes important to develop methods that may be used to model such propulsion systems not only at design point, but also over the full ight envelope. This research presents a methodology and framework for simulating the performance of boundary layer ingesting propulsion systems at o -design conditions. The method is intended for use as a preliminary design tool that may be used to explore the design space and identify design challenges or potential optimum con gurations. The method presented in this research enables the rapid analysis of novel BLI con gurations at a preliminary design stage. The method was applied to a case study of NASA's N3-X aircraft, a blended wing body concept with a distributed propulsor array ingesting the airframe boundary layer. The performance of two propulsor in the array was compare, one at the airframe centreline and one at the extreme edge of the array. Due to di erence in ow conditions, the centreline propulsor was shown to be more e cient at o -design than the end propulsor. However, this di erence in e ciency disappeared at sea level static where the boundary layer thickness is negligible and mass ow ratio is high. Di erence in thrust produce by the two propulsors was instead due their di erent sizes. Performance of the propulsor array as a whole was also presented both independently and including a link to a pair of turbogenerators to provide power. At o design, it was found that there was a discrepancy between the maximum power available from the turbogenerators at o -design operating points and that demanded by the propulsor array operating at 100% fan rotational speed. This discrepancy means that the propulsor array's performance is limited by the turbogenerators at o -design, particularly for low speed, low altitude operation

Theoretical optimal trajectories for reducing the environmental impact of commercial aircraft operations

This work describes initial results obtained from an ongoing research involving the development of optimization algorithms which are capable of performing multi-disciplinary aircraft trajectory optimization processes. A short description of both the rationale behind the initial selection of a suitable optimization technique and the status of the optimization algorithms is firstly presented. The optimization algorithms developed are subsequently utilized to analyze different case studies involving one or more flight phases present in actual aircraft flight profiles. Several optimization processes focusing on the minimization of total flight time, fuel burned and oxides of nitrogen (NOx) emissions are carried out and their results are presented and discussed. When compared with others obtained using commercially available optimizers, results of these optimization processes show atisfactory level of accuracy (average discrepancies ~2%). It is expected that these optimization algorithms can be utilized in future to efficiently compute realistic, optimal and ‘greener’ aircraft trajectories, thereby minimizing the environmental impact of commercial aircraft operations

Assessment of an energy-efficient aircraft concept from a techno-economic perspective

An increase in environmental awareness in both the aviation industry and the wider global setting has led to large bodies of research dedicated to developing more sustainable technology with a lower environmental impact and lower energy usage. The goal of reducing environmental impact has necessitated research into revolutionary new technologies that have the potential to be significantly more energy efficient than their predecessors. However, for innovative technologies in any industry, there is a risk that adoption will be prohibitively expensive for commercial application. It is therefore important to model the economic factors of the new technology or policy at an early stage of development. This research demonstrates the application of a Techno-economic Environmental Risk Assessment framework that may be used to identify the economic impact of an energy-efficient aircraft concept and the impact that environmental policy would have on the viability of the concept. The framework has been applied to a case study aircraft designed to achieve an energy saving of 60% in comparison to a baseline 2005 entry-into-service aircraft. The model compares the green aircraft concept to a baseline conventional aircraft using a sensitivity analysis of the aircraft direct operating cost to changes in acquisition and maintenance cost. The research illustrates an economically viable region for the technology. Cost margins are identified where the increase in operating cost due to expensive novel technology is counterbalanced by the reduction in cost resulting from low energy consumption. Viability was found to be closely linked to fuel price, with a low fuel price limiting the viability of energy-efficient aviation technology. In contrast, a change in environmental taxation policy was found to be beneficial, with the introduction of carbon taxation incentivising the use of an environmentally optimised aircraft

Water injection on aircraft engines: a performance, emissions and economic study

Although aviation based emissions are not the major sources of atmospheric pollution, their impact around the airport vicinity and the increase in air transport makes it a concern. Water injection on aircraft engines can reduce NOx emissions around the airports significantly. This has been demonstrated in research study by NASA Glenn Research Center in collaboration with Boeing Company. The aim of this study is to investigate the performance, emissions and economic aspects of water ingestion for medium and high bypass ratio jet engines using Cranfield University in-house gas turbine simulation software. British Airways was chosen as a representative airline to be used as case study in order to examine the effects of this technology. Performance and emissions models were developed for the most popular aircraft of the fleet, along with their engines. The simulations were focused on the take-off phase of the aircraft, injecting water in the low pressure compressor (LPC) and the combustor, for different water-toair ratios. The results were optimized in terms of fuel burn and verified against the respective results from the NASA study [1]. Finally, an economic model was developed in order to evaluate the monetary impact of these systems, from the point of view of an airliner with a specific number of aircraft in their fleet. The main outcomes of this study show that LPC water injection can provide more than 10% take-off thrust augmentation in a standard day when in hot days it can exceed 25%. Alternatively, the specific fuel consumption at take-off can reach a 10% reduction, for a fixed take-off thrust level. On the other hand, combustor water injection penalizes the engine performance in all cases. Additionally, depending on the point of injection and the water to air ratio, NOx emissions reduction ranges between 25%-85%. Finally, for the case study examined here, the value for the annual monetary benefit due to water injection can reach 599,654£, without taking into account the airport emission based fees. An investment of such sort could present a dynamic payback period of 7.5 years, assuming constant market interest of 8% and 10 years operational life of the equipment

Considerations on the Numerical Modeling and Performance of Axial Swirlers Under Relight Conditions

Numerical modeling of aero engine combustors under relight conditions is a matter of continuously increasing importance due to the demanding engine certification regulations. In order to reduce the complexity and the cost of the numerical modeling, common practice is to replace the atomizer's swirlers with velocity profiles boundary conditions, very often scaled down from nominal operating conditions assuming similarity of the swirler flowfield. The current numerical study focuses on the flowfield characteristics of an axially swirled atomizer operating within a windmilling engine environment. The scalability of the velocity profile from higher power settings is examined. Observations on the performance of the axial swirler under relight conditions are also made. Experimental data was used as a validation platform for the numerical solver, after a grid sensitivity study and a turbulence model selection process. Boundary conditions for simulating the windmilling environment were extracted from experimental work. The swirler axial and tangential velocity profiles were normalized using the swirler inlet velocity. Results showed that both profiles are only scalable for windmilling conditions of high flight Mach number (! 0.5). At low flight Mach numbers, the actual profile had a lower velocity than that predicted through scaling. The swirl number was found to deteriorate significantly with the flight velocity following a linear trend, reducing significantly the expected flame quality. As a consequence the burner is forced to operate at the edge of its stability loop with low certainty regarding its successful relight

Search for heavy neutral leptons in final states with electrons, muons, and hadronically decaying tau leptons in proton-proton collisions at s \sqrt{s} = 13 TeV

A search for heavy neutral leptons (HNLs) of Majorana or Dirac type using proton-proton collision data at = 13 TeV is presented. The data were collected by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 138 fb−1. Events with three charged leptons (electrons, muons, and hadronically decaying tau leptons) are selected, corresponding to HNL production in association with a charged lepton and decay of the HNL to two charged leptons and a standard model (SM) neutrino. The search is performed for HNL masses between 10 GeV and 1.5 TeV. No evidence for an HNL signal is observed in data. Upper limits at 95% confidence level are found for the squared coupling strength of the HNL to SM neutrinos, considering exclusive coupling of the HNL to a single SM neutrino generation, for both Majorana and Dirac HNLs. The limits exceed previously achieved experimental constraints for a wide range of HNL masses, and the limits on tau neutrino coupling scenarios with HNL masses above the W boson mass are presented for the first time

Measurement of inclusive and differential cross sections for single top quark production in association with a W boson in proton-proton collisions at s \sqrt{s} = 13 TeV

Measurements of the inclusive and normalised differential cross sections are presented for the production of single top quarks in association with a W boson in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data used were recorded with the CMS detector at the LHC during 2016-2018, and correspond to an integrated luminosity of 138 fb$^{−1}$. Events containing one electron and one muon in the final state are analysed. For the inclusive measurement, a multivariate discriminant, exploiting the kinematic properties of the events is used to separate the signal from the dominant $t\bar{t}$ background. A cross section of 79.2 ± 0.9 (stat) $^{+7.7}_{−8.0}$ (syst) ± 1.2 (lumi) pb is obtained, consistent with the predictions of the standard model. For the differential measurements, a fiducial region is defined according to the detector acceptance, and the requirement of exactly one jet coming from the fragmentation of a bottom quark. The resulting distributions are unfolded to particle level and agree with the predictions at next-to-leading order in perturbative quantum chromodynamics