Improving the operating efficiency of the more electric aircraft concept through optimised flight procedures

The increasing awareness of the environmental risks and costs due to the growing demand in aviation has prompted both academic and industrial research into short-term and long-term technologies which could help address the challenges. Among these, the more electric aircraft has been identified as a key design concept which would make aircraft more environmentally friendly and cost effective in the long run. Moreover, the notion of free-flight and optimised trajectories has been identified as a key operational concept which would help curb the environmental effects of aircraft as well as reduce overall costs. The research in this paper presents a methodology in which these two concepts can be coupled to study the benefits of more electric aircraft (MEA) flying optimised trajectories. A wide range of issues from aircraft performance, engine performance, airframe systems operation, power off-take penalties, emission modelling, optimisation algorithms and optimisation frameworks has been addressed throughout the study. The case study is based on a popular short haul flight between London Heathrow and Amsterdam Schiphol. The culmination of the study establishes the advantage of the MEA over conventional aircraft and also addresses the enhanced approach to the classical aircraft trajectory optimisation problem. The study shows that the operation procedures to achieve a minimum fuel burn are significantly different for a conventional aircraft and MEA. Trajectory optimisation reduced the fuel burn by 17.4% for the conventional aircraft and 12.2% for the more electric compared to the respective baseline cases. Within the constraints of the study, the minimum fuel burn trajectory for the MEA consumed 9.9% less fuel than the minimum fuel burn trajectory for the conventional aircraft

Environmental Impact Assessment, on the Operation of Conventional and More Electric Large Commercial Aircraft

Global aviation is growing exponentially and there is a great emphasis on trajectory optimization to reduce the overall environmental impact caused by aircraft. Many optimization techniques exist and are being studied for this purpose. The CLEAN SKY Joint Technology Initiative for aeronautics and Air transport, a European research activity run under the Seventh Framework program, is a collaborative initiative involving industry, research organizations and academia to introduce novel technologies to improve the environmental impact of aviation. As part of the overall research activities, "green" aircraft trajectories are addressed in the Systems for Green Operations (SGO) Integrated Technology Demonstrator. This paper studies the impact of large commercial aircraft trajectories optimized for different objectives applied to the on board systems. It establishes integrated systems models for both conventional and more electric secondary power systems and studies the impact of fuel, noise, time and emissions optimized trajectories on each configuration. It shows the significant change in the fuel burn due to systems operation and builds up the case as to why a detailed aircraft systems model is required within the optimization loop. Typically, the objective in trajectory optimization is to improve the mission performance of an aircraft or reduce the environmental impact. Hence parameters such as time, fuel burn, emissions and noise are key optimization objectives. In most instances, trajectory optimization is achieved by using models that represent such parameters. For example aircraft dynamics models to describe the flight performance, engine models to calculate the fuel burn, emissions and noise impact, etc. Such techniques have proved to achieve the necessary level of accuracy in trajectory optimization. This research enhances previous techniques by adding in the effect of systems power in the optimization process. A comparison is also made between conventional power systems and more electric architectures. In the conventional architecture, the environmental control system and the ice protection system are powered by engine bleed air while actuators and electrics are powered by engine shaft power off-takes. In the more electric architecture, bleed off take is eliminated and the environmental control system and ice protection system are also powered electrically through engine shaft power off takes

Effects of Fibrolytic Enzymes on \u3cem\u3ein Vitro\u3c/em\u3e Ruminal Fermentation and Methane Production from \u3cem\u3ePanicum maximum\u3c/em\u3e (Wild Guinea Grass--Ecotype A) and Rice Straw (\u3cem\u3eOryza sativa\u3c/em\u3e)

The wide gap between an animal’s energy requirement and the nutrients available from feeds is a major constraint in animal productivity and should urgently be addressed with novel methods to improve feed utilization and efficiency (Murad and Azzaz 2010). Forages such as Guinea grass (Panicum maximum) and agricultural by products such as rice (Oryza sativa) straw play a vital role as animal feeds in the tropics. However, the total energy requirement of animal cannot be met due to the high fiber content and low digestibility of these feeds. The low digestibility of these feeds not only limits the available energy to the animal, it also accelerates enteric methane (CH4) production a potent greenhouse gas. Supplementation of ruminant diets with exogenous enzymes has recently gained considerable attention as a promising area with potential to improve animal productivity through enhanced digestibility and environment impact. As a starting point in the screening and selection of suitable enzymes and/or enzyme additives to use as feed additives, this study aimed to determine the effects of fibrolytic enzymes on in vitro ruminal fermentation and methane production of two fibrous feeds in artificial ruminal conditions

IMPROVEMENT OF SOIL CHARACTERISTICS UNDER CROP-STOCK INTEGRATION

Soil characteristics and vegetation properties of Diggassawela farm belong to Diddenipothaplantation Limited (approximately 10 km from Kamburupitiya) was studied in view ofevaluating the impact of crop > stock long term integration. Crop - stock integration hasbeen practiced in this farm for more than a decade. Compost and farmyard waste wereintensively used for tea replanting purposes and pasture cultivation respectively. Soilsamples were collected randomly from (3 replicate/location) cattle courtyard, pasture landand compared with an abandoned tea land soil in the same area.The soil pH ranged from 806 for pasture land and 4.53 for an abandoned tea land (P <0.(5). Moisture content of the soil was highest in pastureland (19.7%) while the lowestvalue was observed in the abandoned tea land (8.63'Yo). Pasture land soil had the highestporosity (52.63%) with the lowest bulk density (Ll Jg/crrr'). In contrast the abandoned tealand soil had the lowest porosity (42.04%) 'with the highest bulk density (l.54g!cm3) due toit's high clay percentage. True density of pasture land soil, cattle court yard soil and erodedtea land soil were 2.20 g/crrr', 2.25 g/cnr' and 2.48 g/cnr' respectively (P>0.05). The soilcharacteristics of pastureland compared with other two sites shows improvement due tonutrient recycling via dairy washings and litter accumulation.The observations also revealed that the grass yield and longevity of the pastures andfodder were improved significantly with a pplication of farmyard waste. Application ofcompost also improved the soil properties and increased the rate of survival of tea plants(replanting).The results suggest that the waste materials such as excreta, residues of feeding materials,bedding and dairy washings thus produced various benefits with passage of time anddemonstrated potential for the sustainability of a crop - livestock integration system. It issuggested that crop - livestock integration could be successfully used for the rehabilitationof tea lands on a long-term basis

Impact of aircraft systems within aircraft operation: A MEA trajectory optimisation study

Air transport has been a key component of the socio-economic globalisation. The ever increasing demand for air travel and air transport is a testament to the success of the aircraft. But this growing demand presents many challenges. One of which is the environmental impact due to aviation. The scope of the environmental impact of aircraft can be discussed from many viewpoints. This research focuses on the environmental impact due to aircraft operation. Aircraft operation causes many environmental penalties. The most obvious is the fossil fuel based fuel burn and the consequent greenhouse gas emissions. Aircraft operations directly contribute to the CO2 and NOX emissions among others. The dependency on a limited natural resource such as fossil fuel presents the case for fuel optimised operation. The by-products of burning fossil fuel some of which are considered pollutants and greenhouse gases, presents the case for emissions optimised operations. Moreover, when considering the local impact of aircraft operation, aircraft noise is recognised as a pollutant. Hence noise optimised aircraft operation needs to be considered with regards to local impacts. It is clear whichever the objective is, optimised operation is key to improving the efficiency of the aircraft. The operational penalties have many different contributors. The most obvious of which is the way an aircraft is flown. This covers the scope of aircraft trajectory and trajectory optimisation. However, the design of the aircraft contributes to the operational penalties as well. For example the more-electric aircraft is an improvement over the conventional aircraft in terms of overall efficiency. It has been proven by many studies that the more-electric concept is more fuel efficient than a comparable conventional aircraft. The classical approach to aircraft trajectory optimisation does not account for the fuel penalties caused due to airframe systems operation. Hence the classical approach cannot define a conventional aircraft from a more-electric aircraft. With the more-electric aircraft expected to be more fuel efficient it was clear that optimal operation for the two concepts would be different. This research presents a methodology that can be used to study optimised trajectories for more-electric aircraft. The study present preliminary evidence of the environmental impact due to airframe systems operation and establishes the basis for an enhanced approach to aircraft trajectory optimisation which include airframe system penalties within the optimisation loop. It then presents a suite of models, the individual modelling approaches and the validation to conduct the study. Finally the research presents analysis and comparisons between the classical approach where the aircraft has no penalty due to systems, the conventional aircraft and the more-electric aircraft. When the case studies were optimised for the minimum fuel burn operation, the conventional airframe systems accounted for a 16.6% increase in fuel burn for a short haul flight and 6.24% increase in fuel burn for a long haul flight. Compared to the conventional aircraft, the more electric aircraft had a 9.9% lower fuel burn in the short haul flight and 5.35% lower fuel burn in the long haul flight. However, the key result was that the optimised operation for the moreelectric aircraft was significantly different than the conventional aircraft. Hence this research contributes by presenting a methodology to bridge the gap between theoretical and real aircraft-applicable trajectory optimisation

Effects of Tropical High Tannin Non Legume and Low Tannin Legume Browse Mixtures on Fermentation Parameters and Methanogenesis Using Gas Production Technique

In vitro experiments were conducted to evaluate the suitability of several mixtures of high tanniniferous non legumes with low tanniniferous legumes on in vitro gas production (IVGP), dry matter degradation, Ammonia-N, methane production and microbial population. Eight treatments were examined in a randomized complete block design using four non-legumes and two legumes (Carallia integerrima×Leucaena leucocephala (LL) (Trt 1), C. integerrima×Gliricidia sepium (GS) (Trt 2), Aporosa lindeliyana×LL (Trt 3), A. lindeliyana×GS (Trt 4), Ceiba perntandra×LL (Trt 5), C. perntandra×GS (Trt 6), Artocarpus heterophyllus×LL (Trt 7), A. heterophyllus×GS (Trt 8). The condensed tannin (CT) content of non legumes ranged from 6.2% (Carallia integerrima) to 4.9% (Ceiba perntandra) while the CT of legumes were 1.58% (Leucaena leucocephala) and 0.78% (Gliricidia sepium). Forage mixtures contained more than 14% of crude protein (CP) while the CT content ranged from 2.8% to 4.0% respectively. Differences (p0.05) NH3-N (ml/200 mg DM) production was observed with the A. heterophyllus×G. sepium (Trt 8) mixture which may be attributed with it’s highest CP content. The correlation between IVGP and CT was 0.675 while IVGP and CP was 0.610. In vitro dry matter degradation (IVDMD) was highest in Trt 8 as well. Methane production ranged from 2.57 to 4.79 (ml/200 mg DM) to be synonimous with IVGP. A higher bacteria population (p<0.05) was found in C. perntandra×G. sepium (Trt 6) followed by Artocarpus heterophyllus+G. sepium (Trt 8) and the same trend was observed with the protozoa population as well. The results show that supplementing high tannin non leguminous forages by incremental substitution of legume forage increased gas production parameters, NH3-N, IVDMD and microbial population in the fermentation liquid. Methane production was not significantly affected by the presence of CT or different levels of CP in forage mixtures. Among non legumes, Ceiba perntandra and Artocarpus heterophyllus performed better in mixture with L. leucocephala and G. sepium

Effects of Tropical High Tannin Non Legume and Low Tannin Legume Browse Mixtures on Fermentation Parameters and Methanogenesis Using Gas Production Technique

In vitro experiments were conducted to evaluate the suitability of several mixtures of high tanniniferous non legumes with low tanniniferous legumes on in vitro gas production (IVGP), dry matter degradation, Ammonia-N, methane production and microbial population. Eight treatments were examined in a randomized complete block design using four non-legumes and two legumes (Carallia integerrima×Leucaena leucocephala (LL) (Trt 1), C. integerrima×Gliricidia sepium (GS) (Trt 2), Aporosa lindeliyana×LL (Trt 3), A. lindeliyana×GS (Trt 4), Ceiba perntandra×LL (Trt 5), C. perntandra×GS (Trt 6), Artocarpus heterophyllus×LL (Trt 7), A. heterophyllus×GS (Trt 8). The condensed tannin (CT) content of non legumes ranged from 6.2% (Carallia integerrima) to 4.9% (Ceiba perntandra) while the CT of legumes were 1.58% (Leucaena leucocephala) and 0.78% (Gliricidia sepium). Forage mixtures contained more than 14% of crude protein (CP) while the CT content ranged from 2.8% to 4.0% respectively. Differences (p<0.05) were observed in in vitro gas production (IGVP) within treatments over a 48 h period dominated by C. perntandra×G. sepium (Trt 6). The net gas production (p<0.05) was also high with Trt6 followed by A. heterophyllus×L. leucocephala (Trt 7) and A. heterophyllus×G. sepium (Trt 8). Highest (p>0.05) NH3-N (ml/200 mg DM) production was observed with the A. heterophyllus×G. sepium (Trt 8) mixture which may be attributed with it’s highest CP content. The correlation between IVGP and CT was 0.675 while IVGP and CP was 0.610. In vitro dry matter degradation (IVDMD) was highest in Trt 8 as well. Methane production ranged from 2.57 to 4.79 (ml/200 mg DM) to be synonimous with IVGP. A higher bacteria population (p<0.05) was found in C. perntandra×G. sepium (Trt 6) followed by Artocarpus heterophyllus+G. sepium (Trt 8) and the same trend was observed with the protozoa population as well. The results show that supplementing high tannin non leguminous forages by incremental substitution of legume forage increased gas production parameters, NH3-N, IVDMD and microbial population in the fermentation liquid. Methane production was not significantly affected by the presence of CT or different levels of CP in forage mixtures. Among non legumes, Ceiba perntandra and Artocarpus heterophyllus performed better in mixture with L. leucocephala and G. sepium

COMPARISON OF SOIL QUALITY PARAMETERS UNDER DIFFERENT VEGETATIONS

A short-term field experiment was conducted to study the effects of differentvegetation covers on the soil fertility status. Soil samples were taken fromseveral fields from Mapalana farm. The treatments were grass x legumemixed sward (T1), grass monoculture (T2), legume monoculture (T3),vegetable (T4), coconut field with natural vegetation (T5), forest land (T6),bare land (T7) and cover crop grown with rubber (T8).Each field was divided in to 20 x 20 m four blocks and four random samplesfrom each block were taken at 0-10 em depth. Soil samples were passedthrough 0.2 mm sieve and finely ground for subsequent analysis. Sampleswere analysed to determine the pH and organic matter content. Soil nitrogenpercentage was analysed by the Kjeldhal method. Bulk density wasdetermined using the soil core method and oven drying at 105° C until aconstant weight was obtained.Soil organic matter content ranged from 3.622 % ± 0.819 (grass x legumemixed sward) to 1.433 % ± 0.833 (vegetable). Grass, legume, forest andcoconut land had medium organic matter contents. Vegetable land had theleast organic matter content may be due to chemical fertilizer application.Soil nitrogen percentage was also highest in mixed culture (0.1812 % ±0.0016) followed by the legume crop (0.162 % ± 0.0089) showing thebenefits of nitrogen fixation and transfer in increasing soil organic matter andnitrogen. The nitrogen content of coconut land was also higher (0.1384 % ±0.0157) due to nitrogen recycling via buffalo manure. Similarly nitrogenpercentage of the soil was lowest in vegetable cultivation (0.0571 % ±0.0088).In contrast, soil bulk density was higher (p&lt;0.05) in coconut land (1.491g/cm ' ± 0.1037). This may be due to the soil compactions occurred by longtermbuffalo grazing. Undisturbed lands such as forest cover, cover crop withrubber plantation etc. had lower bulk densities (1.257 g/crrr' ± 0.369 and1.255 g/crrr' ± 0.033 respectively). Highest value (P&lt;0.05) of pH wasobserved in grass monoculture (6.3933 ± 0.311). Mild acidic conditions of soils were shown in mix culture (4.84 ± 0.29), vegetable (4.59 ± 0.22), bareland (4.89 ± 0.20) with cover crop grown with rubber (5.12 ± 0.25)The study concluded that the grass x legume mix culture showed benefits ofnitrogen fixation and transfer associated with higher total nitrogen andorganic matter content in soil. Positive impact on soil nitrogen status onbuffalo grazing showed negative impact on soil bulk density. Humanintervention such as chemical fertilizer application etc also affect on soilcharacteristics.