Configuration Flatness of Lagrangian Systems Underactuated by One Control

Lagrangian control systems that are differentially flat with flat outputs that only depend on configuration variables are said to be configuration flat. We provide a complete characterisation of configuration flatness for systems with n degrees of freedom and n - 1 controls whose range of control forces only depends on configuration and whose Lagrangian has the form of kinetic energy minus potential. The method presented allows us to determine if such a system is configuration flat and, if so provides a constructive method for finding all possible configuration flat outputs. Our characterisation relates configuration flatness to Riemannian geometry. We illustrate the method by two examples

A Test for Differential Flatness by Reduction to Single Input Systems

For nonlinear control systems (p inputs), we present a test for flatness. The method consists of making an initial guess for p-1 of the flat outputs, which may involve parameters still to be determined. A choice of functions of time for the p-1 outputs reduce the system to one with a single input. For single input systems the problem of flatness has been solved and thus leads to the identification of the last flat output, or to obstructions to flatness under the hypotheses. We demonstrate the method for a coupled rigid body in ℝ2 and for a single rigid body in ℝ3

MANAGEMENT INNOVATION CAPABILITIES: CASE STUDY OF A RAIL ORGANISATION

Management innovation is a research area which can contribute at the policy and strategic levels to innovate management models and principles. To initiate and implement a management innovation requires multiple capabilities. Entrepreneurship and leadership theories discuss various capabilities for innovation, however capabilities for management innovation are not defined, moreover capabilities discussed in these theories overlap. Understanding the capabilities can enable managers to implement a management innovation. The purpose of this article is to show capabilities to initiate and implement a management innovation using driving, developing and deploying framework, with empirical evidence from a large rail organisation in Australia

Differential flatness and absolute equivalence

In this paper we give a formulation of differential flatness-a concept originally introduced by Fliess, Levine, Martin, and Rouchon (1992)-in terms of absolute equivalence between exterior differential systems. Systems which are differentially flat have several useful properties which can be exploited to generate effective control strategies for nonlinear systems. The original definition of flatness was given in the context of differential algebra, and required that all mappings be meromorphic functions. Our formulation of flatness does not require any algebraic structure and allows one to use tools from exterior differential systems to help characterize differentially flat systems. In particular, we show that in the case of single input control systems (i.e., codimension 2 Pfaffian systems), a system is differentially flat if and only if it is feedback linearizable via static state feedback. However, in higher codimensions feedback linearizability and flatness are not equivalent: one must be careful with the role of time as well the use of prolongations which may not be realizable as dynamic feedbacks in a control setting. Applications of differential flatness to nonlinear control systems and open questions are also discussed

Differential Flatness and Absolute Equivalence

In this paper we give a formulation of differential flatness---a concept originally introduced by Fleiss, Levine, Martin, and Rouchon---in terms of absolute equivalence between exterior differential systems. Systems which are differentially flat have several useful properties which can be exploited to generate effective control strategies for nonlinear systems. The original definition of flatness was given in the context of differentiable algebra, and required that all mappings be meromorphic functions. Our formulation of flatness does not require any algebraic structure and allows one to use tools from exterior differential systems to help characterize differentially flat systems. In particular, we shown that in the case of single input control systems (i.e., codimension 2 Pfaffian systems), a system is differentially flat if and only if it is feedback linearizable via static state feedback. However, in higher codimensions feedback linearizability and flatness are *not* equivalent: one must be careful with the role of time as well the use of prolongations which may not be realizable as dynamic feedbacks in a control setting. Applications of differential flatness to nonlinear control systems and open questions will be discussed. Revised 14 Aug 9

A Comparative Study on Accuracy of Cockcroft-Gault and MDRD Formulae with 24 Hour Urine Creatinine Clearance in Estimating Glomerular Filtration Rate

Estimation of the glomerular filtration rate (GFR) is important in clinical practice that too in intensive care setting. Most of the antibiotics and drugs that are used in ICU setting are excreted via the kidney. The MDRD formula and Cockcroft Gault equation are most commonly used to calculate GFR. Usefulness of these formulas in clinical setting is dependent on precision and bias. So this study is designed to evaluate these formulas with 24 hour urine creatinine clearance in critically ill patients by calculating correlation coefficient. MATERIALS AND METHODS: This study was conducted in 100 adult patients of Govt, Rajaji, hospital, Madurai. We estimated Creatinine Clearance by CG and MDRD formula and measured GFR by 24 hrs urine creatinine clearance. Bland Altman plot was used to find the difference between the paired observations. RESULTS: The mean GFR measured by 24 hours urine creatinine clearance was 44.75ml/min/1.73m2 (95% CI: 41.13 to 48.37). The mean glomerular filtration rate calculated by Cockcroft-Gault formula was 56.48ml/min/1.73m2 (95%CI: 52.45 to 60.51) and by MDRD formula was 48.71ml/min/m2 (95% CI: 44.80 to 52.62). Correlation coefficient for comparison of CG formula/24 hour urine creatinine clearance and MDRD/24 hour urine clearance were 0.90956 with p value of <0.0001 and 0.9303 with p value of <0.0001 respectively. Bias is defined as the mean difference between calculated and measured GFR. In our study bias was 11.73ml/min for Cockcroft-Gault equation and 3.961ml/min for MDRD equation. This indicates overestimation of glomerular filtration rate by these two formulas. CONCLUSION: C-G and MDRD equations can be an alternative to the CrCl test for assessing GFR, thus avoiding the need for the cumbersome and expensive GFR test. The MDRD formula had greater validity than the C-G equation

Seasonal hand line fishery for yellowfin tuna at Colachel

In Tamil Nadu, the oceanic tunas like skipjack and yellowfin tuna are exploited mainly by multiday drift gill netters. However, in Colachel, Kanyakumari, there is a seasonal fishery targeting yellowfin tuna of medium size weighing around 30 kg, with hand lines that are operated from multiday trawlers. This is an additional income for both the fishermen and the trawl boat owners

A pilot study on the isolation and biochemical characterization of Pseudomonas from chemical intensive rice ecosystem

In recent times, there has been a renewed interest in the search of plant growth promoting rhizobacteria (PGPR) for sustainable crop production. Rice is an economically important food crop, which is subjected to infection by a host of fungal, viral and bacterial pathogens. In this study, an attempt was made to isolate Pseudomonas spp., a potent PGPR in the rhizosphere. Through appropriate microbiological and biochemical methods, the study demonstrated the presence of fluorescent and nonfluorescent Pseudomonads in the rhizosphere of chemical intensive rice growing environments. Augmentation of such PGPR including, Pseudomonads in the rice ecosystems will ensure a healthy micro climate for rice.Key words: Pseudomonas, rice, plant growth promoting rhizobacteria (PGPR)

Tuna drift gillnet fishery at Chennai, Tamil Nadu- an update

The present study describes the status of multiday drift gillnet fishery for tuna from Chennai fishing harbour based on data for the years 2016 – 2017. The data is also compared with that during 1999- 2006. Both the craft and gear increased in size with consequent extension of fishing grounds and increase in the number of days/ fishing trip. The size of the boats increased to 20-23 m OAL from 11-12 m OAL and weight of the gear from 1 to more than 6 t. Annual average catch increased to 8523 t during 2016-2017 from 595 t during 1999-2006. Average catch per unit effort was 8310 kg as against 730 kg during 1999-2006. Yellowfin tuna, Thunnus albacares and Skipjack tuna, Katsuwonus pelamis were the dominant species. The stock position of skipjack tuna and yellowfin tuna vis-àvis the three indicators indicated that the percentage of mature yellowfin tuna in the catch in 2017 was 68%, fish in optimum length 35% and mega-spawners 33% whereas in skipjack tuna the respective percentages were 99.5, 21.1 and 79.1. Problems and prospects of multiday tuna drift gillnet fishery are also discussed

The effects of intrinsic noise on the behaviour of bistable cell regulatory systems under quasi-steady state conditions

We analyse the effect of intrinsic fluctuations on the properties of bistable stochastic systems with time scale separation operating under1 quasi-steady state conditions. We first formulate a stochastic generalisation of the quasi-steady state approximation based on the semi-classical approximation of the partial differential equation for the generating function associated with the Chemical Master Equation. Such approximation proceeds by optimising an action functional whose associated set of Euler-Lagrange (Hamilton) equations provide the most likely fluctuation path. We show that, under appropriate conditions granting time scale separation, the Hamiltonian can be re-scaled so that the set of Hamilton equations splits up into slow and fast variables, whereby the quasi-steady state approximation can be applied. We analyse two particular examples of systems whose mean-field limit has been shown to exhibit bi-stability: an enzyme-catalysed system of two mutually-inhibitory proteins and a gene regulatory circuit with self-activation. Our theory establishes that the number of molecules of the conserved species are order parameters whose variation regulates bistable behaviour in the associated systems beyond the predictions of the mean-field theory. This prediction is fully confirmed by direct numerical simulations using the stochastic simulation algorithm. This result allows us to propose strategies whereby, by varying the number of molecules of the three conserved chemical species, cell properties associated to bistable behaviour (phenotype, cell-cycle status, etc.) can be controlled.Comment: 33 pages, 9 figures, accepted for publication in the Journal of Chemical Physic