Requirements Analysis for Design Optimization of Aerobatic Aircraft

Aerobatic aircraft design and simulation is challenging as these aircraft need to fly at any angle of attack and sideslip angle (full-envelope aerodynamics). They fly at velocities close to stall speed, all the way up to the never exceed velocity. These aircraft are also routinely stressed to 6-12 g's in both upright and inverted flight. Presently, most aerobatic aircraft are designed using heuristic knowledge. There is a need for a systematic approach to design aerobatic aircraft in a multi-disciplinary design framework. Towards this goal, this paper presents an extensive study of requirements, metrics and design variables to define a good aerobatic aircraft. First a historical perspective is given to know the current state-of-the-art. Information obtained from regulations, aircraft performance, subject matter experts and analysis of existing aircraft is used to obtain metrics to evaluate. The possible design configurations is given as a morphological matrix. Finally, possible analysis approaches to evaluate the metrics are discussed

Antistress and antimicrobial studies of biphenyl chalcone derivatives

This work reports the synthesis, characterization of new (2E)-1-(biphenyl-4-yl)-3-aryl)-prop-2-en-1-one derivatives (C1-C10). The chalcone derivatives were evaluated for in vitro antibacterial, antifungal, antioxidant activities. The compounds exhibited moderate to good antimicrobial activity at MIC 10-40 μg/mL. The compounds were docked at the active site of the methionyl-tRNA synthetase (metRS) (PDB ID: 1A8H) to predict their putative interactions. The compounds further screened for antioxidant property, amid C5, C7 and C8 exhibited good DPPH radical scavenging activity. Compound C5 was selected for antistress studies against gamma radiation induced oxidative stress markers in E .coli K 12. The C5 pretreatment and irradiated bacteria sample showed modulatory action of stress enzymes SOD and CAT to near basal level and significant demulating effect on the level of TBARS.Keywords: Biphenyl chalcone derivatives, radioprotection, antioxidant activity, antimicrobial activity, molecular dockin

Protective effect of bischalcone derivative in Drosophila melanogaster against electron beam radiation

In this paper the protective effect of (2E, 5E) – 2,5-bis (3-methoxy-4-hydroxybenzylidene) cyclopentanone bischalcone derivative (Curcumin analogue, CA), on electron beam radiation induced oxidative stress in Drosophila melanogaster adult flies. Curcumin (CU) was taken as standard. The CA pre treated and irradiated flies were screened for wing shape abnormalities in F1 and F2 generations. There was considerable decrease in the wing shape abnormality frequency in the case of CA fed irradiated flies compared to control

Structural Analysis and Optimization of Aircraft Wings Through Dimensional Reduction

Federal Aviation Regulations (FARs) are key drivers of aircraft design. Early-stage aircraft design involves a tight coupling between structural dynamics, aerodynamics, and flight mechanics, with time-dependent loads arising from the considerations of the FARs. The current state-of-the-art decouples the time-domain simulation from the stress/strain computation. Further, simplifying assumptions do not account for the intricate features of the internal structure present in an aircraft wing. Beam theory for structural analysis has been successfully applied to the design of other slender structures subjected to time-dependent loads, like rotorcraft blades. While aircraft wings can be considered slender structures, aperiodicity and inhomogeneity along the span render beam theory ineffective. The present work aims to bridge this gap by proposing a method for analyzing 3-D structures through dimensional reduction. 1-D models are computationally efficient and can be used in the time-domain to obtain the loads. The Variational Asymptotic Method (VAM) allows for the systematic reduction of 3-D structures to 1-D models and further recover 3-D stresses and strains after solving the 1-D problem. A structural optimization framework was developed for the unique analysis method presented, allowing for sizing the structure under strength considerations. Findings show that: 1) the use of VAM allows for the systematic extraction of beam properties for aircraft wings, 2) the displacement and stress response of the aircraft using beam models match reasonably well against those produced by shell-based models, 3) for dynamic simulations the derived adjoint method computes accurate gradients efficiently to be used in structural optimization, 4) sizing of aircraft wings for 14 CFR specified maneuvers using the proposed approach produces a 6\% error compared to shell-based method, but with a 7.8x speed-up. The proposed approach provides improvements on the existing literature methods- it is computationally efficient, provides reasonable accuracy for early-stage structural sizing and weight prediction, and includes dynamic effects. The computational efficiency makes it well-suited for many-query applications like optimization, uncertainty quantification, and generating data for surrogate modeling.Ph.D

Manifold Alignment-Based Multi-Fidelity Reduced-Order Modeling Applied to Structural Analysis

This work presents the application of a recently developed parametric, non-intrusive, and multi-fidelity reduced-order modeling method on high-dimensional displacement and stress fields arising from the structural analysis of geometries that differ in the size of discretization and structural topology.The proposed approach leverages manifold alignment to fuse inconsistent field outputs from high- and low-fidelity simulations by individually projecting their solution onto a common subspace. The effectiveness of the method is demonstrated on two multi-fidelity scenarios involving the structural analysis of a benchmark wing geometry. Results show that outputs from structural simulations using incompatible grids, or related yet different topologies, are easily combined into a single predictive model, thus eliminating the need for additional pre-processing of the data. The new multi-fidelity reduced-order model achieves a relatively higher predictive accuracy at a lower computational cost when compared to a single-fidelity model.Comment: The peer-reviewed and corrected version of this article has been accepted for publication in the Structural and Multidisciplinary Optimization Journa

ANTIBACTERIAL AND IN VITRO ANTIOXIDANT ACTIVITIES OF SOME 4-AMINO-1,2,4-TRIAZOLE-5(4H)-THIONE DERIVATIVES

This work represents the synthesis and characterization some new versatile intermediates namely4-amino-1,2,4-triazole-5(4<em>H</em>)-thionederivatives in a one-step  fusion method. The method works to be superior compared to the existing method by Reed and Handel which consists of four steps. The antibacterial activity of compounds is tested against <em>Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Staphilococcusaureus</em>. The compounds exhibited species specific activity. Among the tested compounds,<strong>1a</strong> and <strong>1b</strong> exhibited good activity at moderately low concentration (31.25µg/mL)against tested strains of bacteria.DPPH (1,1-diphenyl-2-picryl-hydrazyl), FRAP (ferric reducing antioxidant power) and Lipid peroxidation assays are performed to determine the<em>in vitro</em> antioxidant activities. The compound <strong>1e</strong> exhibited good antioxidant activity among the tested compounds

Evaluation of Off-Nominal Performance and Reliability of a Distributed Electric Propulsion Aircraft during Early Design

AIAA Scitech 2021 Forum (AIAA 2021-1723).General Aviation (GA) is likely to be at the forefront of a paradigm change in aviation, where the introduction of novel concepts such as Urban Air Mobility (UAM), architectures like e-VTOL, and technologies like Distributed Electric Propulsion (DEP) are expected to make aircraft more efficient and reduce their environmental footprint. However, these architectures carry with them an uncertainty related to the off-nominal operational risk they pose. The limitations and off-nominal operational considerations generally postulated during traditional safety analysis may not be complete or correct for new technologies. While a lot of the literature surveyed focuses on improving traditional methods of safety analysis, it still does not completely address the limitations caused due to insufficient knowledge and experience with transformative technologies. The research objective of the present work is to integrate the Bayesian safety assessment framework developed previously by the authors with conceptual and 6-DoF performance models for DEP aircraft to evaluate off-nominal performance and reliability using information that is typically available in conceptual or preliminary design phases. A case study on the electric power architecture of the the NASA Maxwell X-57 Mod. IV is provided. A maximum potential flight path angle metric, as well as trimmability considerations using a 6-DoF model constructed using available literature help determine hazard severity of power degradation scenarios. Bayesian failure rate posteriors are constructed for the different components in the traction power system, which are used in a Bayesian decision framework. The results indicate that while most of the components in the traction power architecture of the X-57 Mod. IV are compliant with failure rate requirements generated, the batteries, cruise motors, and cruise motor-inverters do not meet those requirements

Synthesis of novel spiropiperidine derivatives and their antimicrobial and antioxidant activities

1391-1408A series of novel spiro-piperidinyl pyrazolones are synthesized by the reaction of N-Boc protected ethyl nipecotate with heteroaryl and alkyl aldehydes in presence of lithium diisopropyl amide (LDA) to yield corresponding β-hydroxy ester, followed by MnO2 oxidation to give β-keto ester. Further reaction of β-keto ester with hydrazine hydrate results in the formation of spiro-piperidinyl pyrazolone scaffold 5a-d which upon N-benzylation followed by deprotection yields compounds 7a-s. The pyrazolone-NH group has been alkylated in compound 5a with ethyl chloroacetate followed by hydrolysis and amide coupling to afford compounds 9a-d. The furan ring in compound 5a is oxidized to carboxylic acid with KMnO4 and coupled with amines to prepare amide derivatives 11a-c. All the synthesized compounds are evaluated for their in vitro antibacterial and antioxidant activity. Compounds 7a-d and 7g-s are found to possess high antibacterial activity and compounds 7a,7b, 9a, 9b, 11a and 11c are found to be potent antioxidants

Effects of Epistemic Uncertainty on Empennage Loads During Dynamic Maneuvers

The Federal Aviation Regulations contain descriptions of a number of dynamic maneuvers that may lead to the development of critical loads for aircraft structural components. The structural members must be sized and designed to withstand such loads, and this must be demonstrated as part of the certification process. Given the high costs of aircraft certification and the programmatic risk associated with design modifications necessitated during later design stages, there is currently a trend towards certification by analysis. Towards this end, from the structural loads perspective, there is a need for a framework that can simulate maneuvers and evaluate the structural loads thus developed. However, in the earlier phases of design, significant epistemic uncertainty may exist with regard to the aircraft mass properties and aerodynamic characteristics, which in turn lead to uncertainty in the maneuver loads. This work demonstrates a methodology that employs sensitivity and Monte Carlo analyses to assess how maneuvering structural loads are affected by uncertainty factors. These analyses are applied to a dynamic simulation model created to simulate a representative business jet performing a checked pitch maneuver. The resultant variability of critical structural loads provides insight into the areas where epistemic uncertainty should be reduced