DILUTION AND SUPPRESSION OF PARTIALLY PREMIXED FLAMES IN NORMAL AND MICROGRAVITY FOR DIFFERENT FUELS

ABSTRACT The suppression of fires and flames is an important area of interest for both terrestrial and space based applications. In this investigation we elucidate the relative efficacy of fuel and air stream inert diluents for suppressing laminar partially premixed flames. A comparison of the effects of fuel and air stream dilution are also made with other fuels. Both counterflow and coflow flames are investigated, with both normal and zerogravity conditions considered for coflow flames. Simulations are conducted for both the counterflow and coflow flames, while experimental observations are made on the coflowing flames. With fuel or air stream dilution, coflow flames are observed to move downstream from the burner after overcoming initial heat transfer coupling. Further increases in diluent result in increases in the flame liftoff height until blow off occurs. The flame liftoff height and the critical volume fraction of extinguishing agent at blow out vary with both equivalence ratio and with the stream in which diluents are introduced. Nonpremixed methane-air flames are more difficult to extinguish than partially premixed flames with fuel stream dilution; whereas, partially premixed methane-air flames are more resistant to extinction than nonpremixed flames with air stream dilution. This difference in efficacy of the fuel and air stream dilution is attributed to the action of the diluent. In leaner partially premixed flames with fuel stream dilution and richer partially premixed flames with air stream dilution the effect of the diluent is to replace the deficient reactant in the system, thus starving the flame. In leaner partially premixed flames with air stream dilution and richer partially premixed flames with fuel stream dilution the effect of the diluent is purely thermal in that it absorbs heat from the flame, until combustion may no longer be sustained. The dilution effect is more effective than the thermal effect. When gravity is eliminated from the 2-D flame the liftoff height decreases and the critical volume fraction of diluent for blow off is also decreased

Taxing cross-border intercompany transactions: are financing activities fungible?

The Organisation for Economic Cooperation and Development (‘OECD’) is currently considering best practice approaches to designing rules to prevent base erosion and profit shifting (‘BEPS’) by multinational enterprises (‘MNEs’). However, the OECD makes a distinction between combating BEPS and reducing distortions between the tax treatment of various methods of financing. Yet, an unequal tax treatment can create distortions, which incentivises tax planning behaviour. Accordingly, this paper aims to improve the tax design of anti-avoidance rules governing MNEs’ cross-border intercompany deductions by introducing the concept of the tax-induced cross-border funding bias. To date, the literature has focussed on the debt bias, which arises from the distortion in the tax treatment between debt and equity financing. On the other hand, the funding bias also includes licensing and leasing activities in addition to debt and equity financing. This presents a novel contribution to the literature. This paper examines the conceptual case for why is might be appropriate and feasible to restrict the tax deductibility of cross-border intercompany interest, dividends, royalties and lease payments given their mobility and fungibility. Specifically, it examines whether it is preferable for MNEs to be subject to economic rent taxation, as is attained through reform proposals such as the Allowance for Corporate Equity (‘ACE’), in this context. This presents a novel proposal for taxing cross-border intercompany economic rents which aligns with the main aim of corporate tax harmonisation; namely: to reduce, if not remove, distortions relating to the taxation of cross-border intercompany activities

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In: abstract book of National Seminar on “Maize for Crop Diversification under Changing Climatic Scenario” jointly organized by MTAI, IIMR and PAU held at Ludhiana, February 9-10, 2020.The post green revolution agriculture is based on generous application of nitrogen (N)-based fertilizers and high-yielding genotypes. Generally, plants cannot utilize more than 40% of the applied nitrogenous fertilizer; hence more than half of the applied fertilizer is lost to the environment and results in environmental pollution via acidification, eutrophication, and depletion of ozone layer by emission of greenhouse gas. Therefore, genetic improvement in nitrogen use efficiency (NUE) in crops is desirable for a sustainable and profitable agriculture. There is a need to identify key regulatory factors playing pivotal role in acquisition, transportation and utilization of N in plants. Among other factors, microRNA (miRNA) mediated gene regulation plays a crucial role in controlling low N stress adaptation and tolerance in plants. In this endeavor, the present study was undertaken to identify N stress responsive miRNAs in maize in tropical maize using high-throughput sequencing. The HKI-163 maize inbred line was grown hydroponically with sufficient nitrogen (2mM) and without nitrogen for 21 days. Observations were recorded on all important shoot and root physiological parameters. The root and shoot samples were deep sequenced for miRNA study. The expression analysis revealed 23 known miRNAs (11 up & 12 down-regulated) in leaf and 3 known miRNAs (1 up & 2 down-regulated) in root, which expressed differentially under N stress. We also identified 53 (20 up & 33 down-regulated) and 26 (9 up & 17 down-regulated) novel miRNAs in leaf and roots respectively. The knowledge gained will help understand the important roles that miRNAs play in maize, while responding to a nitrogen limiting environment.Not Availabl

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In: abstract book of National Seminar on ‘Maize for Crop Diversification under Changing Climatic Scenario’ jointly organized by MTAI, IIMR and PAU at Ludhiana from 09-10 Feb, 2020.The post green revolution agriculture is based on generous application of nitrogen (N)-based fertilizers and high-yielding genotypes. Generally, plants cannot utilize more than 40% of the applied nitrogenous fertilizer; hence more than half of the applied fertilizer is lost to the environment and results in environmental pollution via acidification, eutrophication, and depletion of ozone layer by emission of greenhouse gas. Therefore, genetic improvement in nitrogen use efficiency (NUE) in crops is desirable for a sustainable and profitable agriculture. There is a need to identify key regulatory factors playing pivotal role in acquisition, transportation and utilization of N in plants. Among other factors, microRNA (miRNA) mediated gene regulation plays a crucial role in controlling low N stress adaptation and tolerance in plants. In this endeavor, the present study was undertaken to identify N stress responsive miRNAs in maize in tropical maize using high-throughput sequencing. The HKI-163 maize inbred line was grown hydroponically with sufficient nitrogen (2mM) and without nitrogen for 21 days. Observations were recorded on all important shoot and root physiological parameters. The root and shoot samples were deep sequenced for miRNA study. The expression analysis revealed 23 known miRNAs (11 up & 12 down-regulated) in leaf and 3 known miRNAs (1 up & 2 down-regulated) in root, which expressed differentially under N stress. We also identified 53 (20 up & 33 down-regulated) and 26 (9 up & 17 down-regulated) novel miRNAs in leaf and roots respectively. The knowledge gained will help understand the important roles that miRNAs play in maize, while responding to a nitrogen limiting environment.Not Availabl

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Not AvailableStudying plant response and adaptation under low nitrogen stress condition is pre-requisite to enhance nitrogen use efficiency in crops. The present study investigated the physiological and molecular responses of maize (Zea mays L.) to nitrogen stress during early vegetative stage. Maize seedlings were grown hydroponically under controlled environmental conditions in phytotron. One set of plants were nutritionally stressed by eliminating nitrogen source in hydroponic culture while the other set was provided with nitrogen (2 mM KNO3). Under nitrogen-starvation condition, plant growth and physiological parameters changed dramatically. Significant reduction in chlorophyll content, total soluble proteins and nitrate reductase activity was observed. Further, nitrogen-starvation resulted into differential expression of genes related to nitrogen-assimilation and metabolism. The present study might be useful to improve our understanding towards plants adaptive response under nitrogen-starvation conditions.Not Availabl

The Behavior of Methane-Air Partially Premixed Flames Under Normal- and Zero-G Conditions

Partially premixed flames (PPFs) represent a class of hybrid flames containing multiple reaction zones. These flames are established when less than stoichiometric quantity of oxidizer is molecularly mixed with the fuel stream before entering the reaction zone where additional oxidizer is available for complete combustion. This mode of combustion can be used to exploit the advantages of both nonpremixed and premixed flames regarding operational safety, lower pollutant emissions and flame stabilization. A double flame containing a fuel-rich premixed reaction zone, which is anchored by a nonpremixed reaction zone, is one example of a partially premixed flame. A triple flame is also a PPF that contains three reaction zones, namely, a fuel-rich premixed zone, a fuel-lean premixed zone, and a nonpremixed reaction zone. Herein we focus on two aspects of our investigation, one involving the development of optical diagnostics that can be used on a microgravity rig, which has been recently fabricated, and the other on the numerically predicted differences between normal- and zero-gravity PPFs. Both the measurements and simulations examine the detailed structure of methane-air PPFs stabilized on a Wolfhard-Parker slot burner

Lifted Partially Premixed Flames in Microgravity

Lifted Double and Triple flames are established in the UIC-NASA Partially Premixed microgravity rig. The flames examined in this paper are established above a coannular burner because its axisymmetric geometry allows for future implementation of other non-intrusive optical diagnostic techniques easily. Both burner-attached stable flames and lifted flames are established at normal and microgravity conditions in the drop tower facility

Gravity Effects Observed In Partially Premixed Flames

Partially premixed flames (PPFs) contain a rich premixed fuel air mixture in a pocket or stream, and, for complete combustion to occur, they require the transport of oxidizer from an appropriately oxidizer-rich (or fuel-lean) mixture that is present in another pocket or stream. Partial oxidation reactions occur in fuel-rich portions of the mixture and any remaining unburned fuel and/or intermediate species are consumed in the oxidizer-rich portions. Partial premixing, therefore, represents that condition when the equivalence ratio (phi) in one portion of the flowfield is greater than unity, and in another section its value is less than unity. In general, for combustion to occur efficiently, the global equivalence ratio is in the range fuel-lean to stoichiometric. These flames can be established by design by placing a fuel-rich mixture in contact with a fuel-lean mixture, but they also occur otherwise in many practical systems, which include nonpremixed lifted flames, turbulent nonpremixed combustion, spray flames, and unwanted fires. Other practical applications of PPFs are reported elsewhere. Although extensive experimental studies have been conducted on premixed and nonpremixed flames under microgravity, there is a absence of previous experimental work on burner stabilized PPFs in this regard. Previous numerical studies by our group employing a detailed numerical model showed gravity effects to be significant on the PPF structure. We report on the results of microgravity experiments conducted on two-dimensional (established on a Wolfhard-Parker slot burner) and axisymmetric flames (on a coannular burner) that were investigated in a self-contained multipurpose rig. Thermocouple and radiometer data were also used to characterize the thermal transport in the flame