Sanjiv Sharma

Imperial College · Department of Aeronautics

In this study, we utilize the emerging Physics Informed Neural Networks (PINNs) approach for the first time to predict the flow field of a compressor cascade. Different from conventional training methods, a new adaptive learning strategy that mitigates gradient imbalance through incorporating adaptive weights in conjunction with dynamically adjusti...

In this study, we utilize the emerging Physics Informed Neural Networks (PINNs) approach for the first time to predict the flow field of a compressor cascade. The approach is demonstrated on a two-dimensional problem, incorporating Navier-Stokes equations in both the forward and inverse problems. In the forward problem, PINNs effectively predict th...

A novel algorithm is presented to aid designers during the conceptual design phase of a new engineering product by rapidly assessing new areas of the design space. The algorithm presented here develops a Polynomial Chaos based meta-model that allows the designer to estimate the probability distribution for a candidate design's performance without r...

We introduce a framework for statistical inference of the closure coefficients using machine learning methods. The objective of this framework is to quantify the epistemic uncertainty associated with the closure model by using experimental data via Bayesian statistics. The framework is tailored towards cases for which a limited amount of experiment...

This work presents a machine learning based method for bi-fidelity modelling. The method, a Knowledge Based Neural Network (KBaNN), performs a local, additive correction to the outputs of a coarse computational model and can be used to emulate either experimental data or the output of a more accurate, but expensive, computational model. An advantag...

This work presents a framework for predicting the unknown probability distributions of input parameters, starting from scarce experimental measurements of other input parameters and the Quantity of Interest (QoI), as well as a computational model of the system. This problem is relevant to aeronautics, an example being the calculation of the materia...

This work presents a framework for updating an estimate of a probability distribution, arising from an uncertainty propagation using Non-intrusive Polynomial Chaos (NIPC), with scarce experimental measurements of a Quantity of Interest (QoI). In recent years much work has been directed towards developing methods of combining models of different acc...

This work presents a framework for predicting unknown input distributions for turbomachinery applications starting from scarce experimental measurements. The problem is relevant to turbomachinery where important parameters are obtained using indirect measurements. In this paper a scroll compressor is used as example but the suggested framework is c...

Engineers account for uncertainties by using Design Margins, typically by introducing them implicitly. Although methods for quantifying uncertainty are well established at discipline level, they are not applied systematically. A hierarchy of assumed independent design margins makes it difficult to deduce architect level margins. Further, the implic...

This work presents a framework for upscaling uncertainty in multiscale models. The problem is relevant to aerospace applications where it is necessary to estimate the reliability of a complete part such as an aeroplane wing from experimental data on coupons. A particular aspect relevant to aerospace is the scarcity of data available. The framework...

During the early stages of any system design, a thorough exploration of the design space can prove to be challenging and computationally expensive. The challenges are further exacerbated when dealing with complex systems, such as an aircraft, due to the high dimensionality of their design space. Arising from the Toyota Product Development System, s...

Presented is a strategy for early stage multidisciplinary design of high-lift devices with systems and manufacturing constraints. High-lift devices require a great deal of information which is very often provided only after some of the major design decisions concerning the airframe have already been made. As a consequence, the further in the develo...

Presented are interface specifications and implementations aimed at enabling interactive early stage systems architecting through tighter integration between architecture definition and assessment. Specifically, two approaches for interfacing the logical and computational domains are proposed. The first one employs graph theoretic principles to con...

In this article, justification diagrams are introduced for structuring evidence to support conclusions that are reached from results of simulation studies. An industrial application is used to illustrate the use of the justification diagrams. Adapted from the Toulmin schema, the aim of justification diagram is to define a comprehensive, auditable a...

During product development changes in the initial design are ubiquitous. The ability to predict such changes, along with the expected costs, is a challenge on its own. This challenge increases exponentially when a single design change on one element of the system propagates to other components. As change propagates, so does the cost associated with...

Evaluating the ground-based manoeuvrability of large aircraft is time consuming and costly if explored though simulations with industry-developed complex models of ground dynamics. We argue here that this type of dynamics can be investigated efficiently and with considerable precision by applying dynamical systems techniques. As an example, we cons...

Bifurcation analysis is a powerful method for studying the steady-state nonlinear dynamics of systems. Software tools exist for the numerical continuation of steady-state solutions as parameters of the system are varied. These tools make it possible to generate 'maps of solutions' in an efficient way that provide valuable insight into the overall d...

The Configuration Optimisation of Next-Generation Aircraft (CONGA) is a proposed framework in a response to industrial need to enhance the aerospace capability in the UK. In order to successfully address this challenge, a need to develop a true multi-disciplinary Set-Based Design (SBD) capability that could deploy new technologies on novel configur...

A method, apparatus and software is disclosed for controlling the heading of an aircraft travelling on the ground in which veering is detected and compensatory steering commands generated so as to automatically maintain a reference heading.

Simulation models of plant or actuator dynamics are utilized throughout the development cycle of new control systems. They can be used to validate the performance of a single controller in the presence of parameter variation, or to investigate the behavior when the control loop is embedded within a larger system model. The models may be for desktop...

Under certain conditions during take-off and landing, pilots may sometimes experience quite violent vibrations in the cockpit. Since it is located right above the nose landing gear { which is known to experience self-excited vibrations on the runway { an explanation for those oscillations might be the interaction between the fuselage and the oscill...

This paper describes experiences gained by applying System Engineering (SE) management practices within a particular EU research project (CRESCENDO). Additionally, we attempt to answer the underlying question: to what extent is it practical to apply SE management practices within the context of large-scale, collaborative research projects? A common...

The work presented in this paper describes a new low parameter mathematical model representing the force and moment components generated in an aircraft tyre for use in the computer simulation of takeoff, landing and taxiing manoeuvres of an aircraft. As such the problems addressed fall in the area of ground vehicle dynamics and the modelling of the...

This paper extends previous work on a coupled optimization method for air-port taxiway routing and runway scheduling. An iterative method is used to reduce the computational demand of the required separation constraints whilst introducing no loss in performance. A Receding Horizon (RH) approach is added to further reduce the solution times. As well...