An integrated estimation/guidance approach for seeker-less interceptors

This paper addresses the problem of intercepting highly maneuverable threats using seeker-less interceptors that operate in the command guidance mode. These systems are more prone to estimation errors than standard seeker-based systems. In this paper, an integrated estimation/guidance (IEG) algorithm, which combines interactive multiple model (IMM) estimator with differential game guidance law (DGL), is proposed for seeker-less interception. In this interception scenario, the target performs an evasive bang-bang maneuver, while the sensor has noisy measurements and the interceptor is subject to acceleration bound. The IMM serves as a basis for the synthesis of efficient filters for tracking maneuvering targets and reducing estimation errors. The proposed game-based guidance law for two-dimensional interception, later extended to three-dimensional interception scenarios, is used to improve the endgame performance of the command-guided seeker-less interceptor. The IMM scheme and an optimal selection of filters, to cater to various maneuvers that are expected during the endgame, are also described. Furthermore, a chatter removal algorithm is introduced, thus modifying the differential game guidance law (modified DGL). A comparison between modified DGL guidance law and conventional proportional navigation guidance law demonstrates significant improvement in miss distance in a pursuer-evader scenario. Simulation results are also presented for varying flight path angle errors. A numerical study is provided which demonstrates the performance of the combined interactive multiple model with game-based guidance law (IMM/DGL). Simulation study is also carried out for combined IMM and modified DGL (IMM/modified DGL) which exhibits the superior performance and viability of the algorithm reducing the chattering phenomenon. The results are illustrated by an extensive Monte Carlo simulation study in the presence of estimation errors

Did globalisation aid industrial development in colonial India? A study of knowledge transfer in the iron industry

The article explores the link between international economic integration and technological capability in colonial India. The example of the iron industry shows that many new ideas and skills flowed into India from Europe, but not all met with commercial success. The essay suggests a reason why. In those fields in which the costs of complementary factors were relatively low, the chance of success was higher. This condition was present in the craft of the blacksmith, in which the main complementary input was abundant craftsmanship. The condition was slow to develop in iron-smelting, where the costs of fuel, labour, capital and carriage of ore were initially high

Tigers in the Terai: Strong evidence for meta-population dynamics contributing to tiger recovery and conservation in the Terai Arc Landscape - Fig 2

<p>Minimum Convex Polygon (MCP) from multiyear camera trap surveys carried out in a) core area of Suklaphanta National Park; b) Babai valley within Bardia National Park.</p

Fitted polynomial growth curve based on 3%, 10%, 21% growth rates regressed on minimum population size (M_t+1) of camera trap tiger population surveyed in between 2009 and 2014 in core area of Suklaphanta National Park.

<p>Fitted polynomial growth curve based on 3%, 10%, 21% growth rates regressed on minimum population size (M_t+1) of camera trap tiger population surveyed in between 2009 and 2014 in core area of Suklaphanta National Park.</p

Trend in minimum population size (M_t+1) of the tiger population based on adhoc camera trap tiger population surveyed in between 2006 and 2016 in the core area of Babai Valley within Bardia National Park.

<p>Trend in minimum population size (M_t+1) of the tiger population based on adhoc camera trap tiger population surveyed in between 2006 and 2016 in the core area of Babai Valley within Bardia National Park.</p