Configuration management and automatic control of an augmentor wing aircraft with vectored thrust

An advanced structure for automatic flight control logic for powered-lift aircraft operating in terminal areas is under investigation at Ames Research Center. This structure is based on acceleration control; acceleration commands are constructed as the sum of acceleration on the reference trajectory and a corrective feedback acceleration to regulate path tracking errors. The central element of the structure, termed a Trimmap, uses a model of the aircraft aerodynamic and engine forces to calculate the control settings required to generate the acceleration commands. This report describes the design criteria for the Trimmap and derives a Trimmap for Ames experimental augmentor wing jet STOL research aircraft

Turbojet engine blade damping

The potentials of various sources of nonaerodynamic damping in engine blading are evaluated through a combination of advanced analysis and testing. The sources studied include material hysteresis, dry friction at shroud and root disk interfaces as well as at platform type external dampers. A limited seris of tests was conducted to evaluate damping capacities of composite materials (B/AL, B/AL/Ti) and thermal barrier coatings. Further, basic experiments were performed on titanium specimens to establish the characteristics of sliding friction and to determine material damping constants J and n. All the tests were conducted on single blades. Mathematical models were develthe several mechanisms of damping. Procedures to apply this data to predict damping levels in an assembly of blades are developed and discussed

Varied clinical presentation of Meckel’s diverticulum in pediatric population

Background: Meckel’s diverticulum (MD) is one of the most prevalent congenital abnormalities of the small intestine. Due to its wide-ranging presentations, it often becomes a challenge to diagnose it. Objective: The objective of the study is to analyze varied clinical manifestations of MD in children and their outcomes. Materials and Methods: This was a retrospective study of children diagnosed with MD in the Department of Pediatric Surgery, Medical College of Karnataka from January 2015 to January 2019. A total of 13 patients (10 male and 3 female) aged 1 month–15 years with a diagnosis of MD were included in the study. Their demographic and clinical parameters, investigation, and histopathological findings along with the surgical interventions were collected and analyzed. Results: Patients were presented with varied clinical features such as intestinal obstruction (30.76%), perforated MD (15.38%), diverticulitis (15.38%), gastrointestinal bleed (7.69%), patent vitellointestinal duct (7.69%), and incidental (23.07%). All the cases were investigated and underwent treatment. The most common post-operative complication was wound infection in 2 children which were treated conservatively. Conclusion: A pre-operative diagnosis of complicated MD may be challenging because of the overlapping clinical and imaging features of the other acute surgical and inflammatory conditions of the abdomen. Therefore it is necessary to maintain a high incidence of suspicious in the pediatric age group

Performance of a high T (sub c) superconducting ultra-low loss microwave stripline filter

Discussed here is the successful fabrication of a five-pole interdigital stripline filter made of the 93 K superconductor (Y1Ba2Cu3O sub y) coated on a silver substrate, with center frequency of 8.5 GHz and an extremely high rejection ratio of 80 dB. The lowest injection loss measured was 0.1 dB at 12 K, with a return loss of better than 16 dB, representing a significant improvement over a similar copper filter, and is comparable to low critical temperature filters. The insertion loss appears to be limited by extrinsic factors, such as tuning mismatch and joint losses, and not by superconducting material losses

Kaempferol Treatment after Traumatic Brain Injury during Early Development Mitigates Brain Parenchymal Microstructure and Neural Functional Connectivity Deterioration at Adolescence.

Targeting mitochondrial ion homeostasis using Kaempferol, a mitochondrial Ca2+ uniporter channel activator, improves energy metabolism and behavior soon after a traumatic brain injury (TBI) in developing rats. Because of broad TBI pathophysiology and brain mitochondrial heterogeneity, Kaempferol-mediated early-stage behavioral and brain metabolic benefits may accrue from diverse sources within the brain. We hypothesized that Kaempferol influences TBI outcome by differentially impacting the neural, vascular, and synaptic/axonal compartments. After TBI at early development (P31), functional magnetic resonance imaging and diffusion tensor imaging (DTI) were applied to determine imaging outcomes at adolescence (2 months post-injury). Vehicle and Kaempferol treatments were made at 1, 24, and 48 h post-TBI, and their effects were assessed at adolescence. A significant increase in neural connectivity was observed after Kaempferol treatment as assessed by the spatial extent and strength of the somatosensory cortical and hippocampal resting-state functional connectivity (RSFC) networks. However, no significant RSFC changes were observed in the thalamus. DTI measures of fractional anisotropy (FA) and apparent diffusion coefficient, representing synaptic/axonal and microstructural integrity, showed significant improvements after Kaempferol treatment, with highest changes in the frontal and parietal cortices and hippocampus. Kaempferol treatment also increased corpus callosal FA, indicating measurable improvement in the interhemispheric structural connectivity. TBI prognosis was significantly altered at adolescence by early Kaempferol treatment, with improved neural connectivity, neurovascular coupling, and parenchymal microstructure in select brain regions. However, Kaempferol failed to improve vasomotive function across the whole brain, as measured by cerebrovascular reactivity. The differential effects of Kaempferol treatment on various brain functional compartments support diverse cellular-level mitochondrial functional outcomes in vivo

Experimental studies on combustible fuel block strategy for cooking

This paper presents experimental results of a study on the feasibility of making highly densified fuel block from agro residues that could be used for applications such as domestic cooking and barbecuing. A strategy had been adopted to determine the best suitable raw materials which meet both the criteria of performance and economy. In this regard several experiments were conducted with various raw materials in different proportions and it was found that fuel block composed of 40% biomass, 40% charcoal powder, 15% binder and 5% oxidizer fulfills the requirement of performance as well as economy. The unique geometry of this kind of fuel block (cylindrical one with a number of holes extending from top to bottom unlike traditional biomass briquette with single or no holes) helps in smokeless operation with reasonably steady thermal output. The geometry of the fuel block is so designed that it operates in partially premixed mode of combustion thus leading to better combustion and thereby lower emission. A typical fuel block for cooking weighing about 700-800g provides a thermal output of 1.5 kWth, with a burn time of 1.5 hours. Water boiling tests have indicated a thermal efficiency in the range of 55-58%

Biomass gasification technology - a route to meet energy needs

The paper addresses a distributed power generation system that has evolved at the Indian Institute of Science, Bangalore. The technological and field-related experience pertaining to open top re-burn down draft biomass gasification system coupled with the internal combustion engine or thermal device are brought out. The gasifier reactor design uses dual air entry - air nozzles and open top to help in establishing a thick high temperature zone to remove the contaminants in the product gas; a gas clean-up system to further refine the gas to ultra-pure quality. These elements are integrated with other sub-systems, namely feedstock preparation, ash handling, water treatment, process automation and other accessories to form an Independent Power Producer. Based on this technology there are over 30 units operating in India and abroad, with an accumulated capacity of over 20 MW. Over 80,000 h of operation of these systems have resulted in a saving of about 350 tons of fossil fuel, implying a saving of about 1120 tons of CO2 - a promising candidate for Clean Development Mechanisms (CDMs), other than reduction in toxic gases like NOx and SOx

Biomass derived producer gas as a reciprocating engine fuel-an experimental analysis

This paper uncovers some of the misconceptions associated with the usage of producer gas, a lower calorific gas as a reciprocating engine fuel. This paper particularly addresses the use of producer gas in reciprocating engines at high compression ratio (17 : 1), which hitherto had been restricted to lower compression ratio (up to 12 : 1). This restriction in compression ratio has been mainly attributed to the auto-ignition tendency of the fuel, which appears to be simply a matter of presumption rather than fact. The current work clearly indicates the breakdown of this compression ratio barrier and it is shown that the engine runs smoothly at compression ratio of 17 : 1 without any tendency of auto-ignition. Experiments have been conducted on multi-cylinder spark ignition engine modified from a production diesel engine at varying compression ratios from 11.5 : 1 to 17 : 1 by retaining the combustion chamber design. As expected, working at a higher compression ratio turned out to be more efficient and also yielded higher brake power. A maximum brake power of 17.5 kWe was obtained at an overall efficiency of 21% at the highest compression ratio. The maximum de-rating of power in gas mode was 16% as compared to the normal diesel mode of operation at comparable compression ratio, whereas, the overall efficiency declined by 32.5%. A careful analysis of energy balance revealed excess energy loss to the coolant due to the existing combustion chamber design. Addressing the combustion chamber design for producer gas fuel should form a part of future work in improving the overall efficiency

Simulation of fluid flow in a high compression ratio reciprocating internal combustion engine

This paper discusses the detailed three-dimensional modelling of a reciprocating engine geometry comprising a flat cylinder head and a bowl-in-piston combustion chamber, simulating the motoring or non-firing conditions. The turbulence is modelled using a standard K-ε model and the results are compared against experimental results from the literature. Computed velocity profiles at time steps close to top centre (TC) are presented. The effect of squish and reverse squish becomes significant in a high compression ratio reciprocating engine. This enhanced fluid movement during a reverse squish regime could have an effect on burn rate, particularly in a spark ignition engine fuelled with biomass-derived producer gas, which has optimum ignition timing close to TC

Zero-dimensional modelling of a producer gas-based reciprocating engine

A zero-dimensional modelling study has been conducted using wrinkled flame theory for flame propagation to understand the in-cylinder pressure behaviour with time in a reciprocating internal combustion engine. These are compared with experiments conducted on the engine operated on biomass derived from producer gas and air mixture. The required inputs on the laminar burning velocity and turbulence parameters are obtained from separate studies. The data related to laminar burning velocity for producer gas and air mixture at thermodynamic conditions typical of unburned mixture in an engine cylinder were obtained from one-dimensional flame calculations. The turbulence parameters were obtained by conducting a three-dimensional computational fluid dynamics study on a bowl-in-piston geometry to simulate motored or non-firing conditions. The above mentioned data were used in the zero-dimensional model to make pressure-time (p-θ) computation over the complete engine cycle, for a range of test cases at varying compression ratio (CR) and ignition timing. The computational results matched reasonably well with experimental p-θ curves at advanced ignition timing at all CRs. The error in computed indicated power (IP) at advanced ignition setting (18°-27°CA) is around 3-4 per cent for CR = 17.0 and 11.5, and between 6 and 9 per cent for CR = 13.5. However, at less advanced ignition setting, the error in computed IP is larger and this is attributed to enhanced fluid dynamic effect due to reverse squish effect. And, whenever major part of the combustion occurred during this period, the deviation in the computed result appeared to be larger. This model has also been used to predict output of a commercially available producer gas engine of 60 kW. The optimum ignition timing on this particular engine was experimentally found to be 22°-24° before top centre. The zero-dimensional model has been used in a predictive mode and results compared with brake power under wide throttle open condition