Applications of adjoint theory to problems in aerospace and defence science

The adjoint simulation method is an efficient, computerised method for the performance analysis of linear time varying systems excited by deterministic and/or stochastic inputs. It is based on the impulse response function (or weighting function) of the so-called adjoint system---an associated linear system derived from the original system by clever utilisation of the mathematical principle of duality. We demonstrate the power of adjoint simulation in the context of guided missile homing loop studies and present a Matlab tool for its speedy implementation and execution. As an example, the tool analyses the miss distance performance of a generic guided missile against an evading target in two dimensional space. References Statistical performance analysis of nonlinear stochastic systems by the Monte Carlo method volume 23-1 of Mathematics and Computers in Simulation J., pages 21--23, 1981. doi:10.1016/0378-4754(81)90004-5 Zarchan, P. Tactical and Strategic Missile Guidance, 5th Edition, AIAA Progress in Astronautics and Aeronautics, 2007. Weiss, M. Adjoint Method for Missile Performance Analysis on State-Space Models, volume 28-2 of Guidance, Control and Dynamics J., pages 236--248, AIAA,2005. Laning, J. H. and Battin, R. H. Random Processes in Automatic Control, McGraw-Hill Book Company, New York, NY, 1956. D. Bucco and M. Weiss. Development of a Matlab/Simulink Tool to Facilitate System Analysis and Simulation via the Adjoint and Covariance Methods, AIAA MST Conference, Aug 2007. http://www.aiaa.org/agenda.cfm?lumeetingid=1501&formatview=1&dateget=22-Aug-07 DeRusso, P. M., Roy, R. J., Close, C. M., and Desrochers, A. A. State Variables for Engineers, 2nd Edition, John Wiley and Sons, Inc., New York, NY, 1998. Moretti, G. Best Practices for Adopting Model-Based Design in Electronic System Development, White-paper, Gabe on EDA, 2007. http//www.mathworks.com/products/simulink/technicalliterature.htm

Have U.S. Manufacturing Inventories Really Decreased? An Empirical Study

Numerous normative models have been developed to determine optimal inventory levels, and several articles and case studies have been written about the concerted efforts and practices adopted by manufacturing firms in the United States to reduce inventories. But little is known about whether inventories have indeed decreased in U.S. manufacturing and whether such a decrease has been restricted to a few well-publicized firms or is true at an industry level. Using data published by the U.S. Census Bureau, the authors study trends in materials, work-in-process, and finished-goods inventory ratios during the period 1961 to 1994 in 20 manufacturing industry sectors and the total U.S. manufacturing sector to determine whether a significant decrease was seen in these ratios. Further, since a great deal of momentum for inventory reduction began in the early 1980s, the authors investigate whether greater improvement was seen in the post-1980 period as compared with the pre-1980 period. We find that material and work-in-process inventories did decrease in a majority of the two-digit industry sectors from 1961 to 1994 and showed greater improvement in about half the sectors in the post-1980 period relative to the pre-1980 period. Finished-goods inventories did decrease in some industry sectors and increase in a few others but did not show a significant trend in more than half the sectors. Total manufacturing inventory ratios decreased from 1961 to 1994 at all three stages---material, work-in-process, and finished goods. However, total manufacturing inventory ratios did not improve at a higher rate during the post-1980 period as compared with the pre-1980 period in any of the three stages. Overall, the analysis provides an encouraging but somewhat mixed picture about the results of U.S. manufacturing inventory-reduction efforts.Manufacturing, Inventory, Empirical Study, Time Series

Deprescribing medicines in the acute setting to reduce the risk of falls

BACKGROUND: Falls are a common cause of morbidity and hospitalisation in older people. Inappropriate prescribing and polypharmacy contribute to falls risk in elderly patients. This study's aim was to quantify the problem and find out if medication review in the hospital setting led to deprescribing of medicines associated with falls risk. METHODS: Admissions records for elderly patients were examined to identify those whose presenting complaint included a fall. Inpatient medication charts, pharmaceutical care notes, medical notes and discharge summaries were examined to identify any falls-risk medicines from admission histories and to determine if any medication review took place, and whether or not changes were made as a result. In particular deprescribing and dose reduction details were analysed. RESULTS: 100 patients over 70 years old were admitted following a fall during the 2 months study period. The mean number of medicines on admission was 6.8 per patient with polypharmacy found in 62/100 (62%). One or more falls-risk medicine was found in 65/100 (65%) patients. Medicines review was carried out in 86/100 (86%) of patients, and 59/697 (8.5%) medicines were deprescribed. Pharmacist involvement in medication review led to a significant reduction in the number of falls-risk medicines per patient (p=0.002). CONCLUSIONS: Inappropriate prescribing and polypharmacy are found frequently in elderly patients at admission following a fall. Comprehensive medicines reviews should be carried out in all such patients with the objective of deprescribing or reducing doses to minimise risk of harm. Involvement of a pharmacist improves the rate of reduction of falls-risk medicines

Do adsorbent screening metrics predict process performance? A process optimisation based study for post-combustion capture of CO2

Recent interest in carbon dioxide capture has led to development of hundreds of adsorbents. The selection of the adsorbents and analyzing their performance for a given process is a challenging task. Usually, the expected performances of these adsorbents are evaluated by inspecting the isotherms and using simple adsorbent screening metrics (selectivities, working capacities, figures of merit, etc.). In this work, a process-optimization based approach to screen adsorbents for post-combustion CO2 capture for vacuum swing adsorption (VSA) is presented. Four different adsorbents (Mg-MOF-74, UTSA-16, Zeolite 13X and activated carbon) were chosen as test materials and were subjected to process-optimization studies on a 4-step PSA cycle with light product pressurization (LPP). Two kinds of process optimization studies were performed. The first to maximize purity and recovery and the second to minimize energy consumption and maximize productivity subject to purity/recovery constraints. This study highlights that most commonly used adsorbent metrics do not necessarily rank the performance of the materials at a process scale. It is also shown that the process performance was more sensitive to the affinity of N2 than that of CO2.Fil: Rajagopalan, Ashwin Kumar. University of Alberta; CanadáFil: Avila, Adolfo María. University of Alberta; Canadá. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rajendran, Arvind. University of Alberta; Canad

Game Theory in Defence Applications: A Review

This paper presents a succinct review of attempts in the literature to use game theory to model decision-making scenarios relevant to defence applications. Game theory has been proven as a very effective tool in modelling the decision-making processes of intelligent agents, entities, and players. It has been used to model scenarios from diverse fields such as economics, evolutionary biology, and computer science. In defence applications, there is often a need to model and predict the actions of hostile actors, and players who try to evade or out-smart each other. Modelling how the actions of competitive players shape the decision making of each other is the forte of game theory. In past decades, there have been several studies that applied different branches of game theory to model a range of defence-related scenarios. This paper provides a structured review of such attempts, and classifies existing literature in terms of the kind of warfare modelled, the types of games used, and the players involved. After careful selection, a total of 29 directly relevant papers are discussed and classified. In terms of the warfares modelled, we recognise that most papers that apply game theory in defence settings are concerned with Command and Control Warfare, and can be further classified into papers dealing with (i) Resource Allocation Warfare (ii) Information Warfare (iii) Weapons Control Warfare, and (iv) Adversary Monitoring Warfare. We also observe that most of the reviewed papers are concerned with sensing, tracking, and large sensor networks, and the studied problems have parallels in sensor network analysis in the civilian domain. In terms of the games used, we classify the reviewed papers into papers that use non-cooperative or cooperative games, simultaneous or sequential games, discrete or continuous games, and non-zero-sum or zero-sum games. Similarly, papers are also classified into two-player, three-player or multi-player game based papers. We also explore the nature of players and the construction of payoff functions in each scenario. Finally, we also identify gaps in literature where game theory could be fruitfully applied in scenarios hitherto unexplored using game theory. The presented analysis provides a concise summary of the state-of-the-art with regards to the use of game theory in defence applications and highlights the benefits and limitations of game theory in the considered scenarios

Digital Platforms in the Assessment and Monitoring of Patients with Bipolar Disorder

This paper aims to review the application of digital platforms in the assessment and monitoring of patients with Bipolar Disorder (BPD). We will detail the current clinical criteria for the diagnosis of BPD and the tools available for patient assessment in the clinic setting. We will go on to highlight the difficulties in the assessment and monitoring of BPD patients in the clinical context. Finally, we will elaborate upon the impact that diital platforms have made, and have the potential to make, on healthcare, mental health, and specifically the management of BPD, before going on to evaluate the benefits and drawbacks of the use of such technology

Game Theory in Defence Applications: A Review

This paper presents a succinct review of attempts in the literature to use game theory to model decision-making scenarios relevant to defence applications. Game theory has been proven as a very effective tool in modelling the decision-making processes of intelligent agents, entities, and players. It has been used to model scenarios from diverse fields such as economics, evolutionary biology, and computer science. In defence applications, there is often a need to model and predict the actions of hostile actors, and players who try to evade or out-smart each other. Modelling how the actions of competitive players shape the decision making of each other is the forte of game theory. In past decades, there have been several studies that applied different branches of game theory to model a range of defence-related scenarios. This paper provides a structured review of such attempts, and classifies existing literature in terms of the kind of warfare modelled, the types of games used, and the players involved. After careful selection, a total of 29 directly relevant papers are discussed and classified. In terms of the warfares modelled, we recognise that most papers that apply game theory in defence settings are concerned with Command and Control Warfare, and can be further classified into papers dealing with (i) Resource Allocation Warfare (ii) Information Warfare (iii) Weapons Control Warfare, and (iv) Adversary Monitoring Warfare. We also observe that most of the reviewed papers are concerned with sensing, tracking, and large sensor networks, and the studied problems have parallels in sensor network analysis in the civilian domain. In terms of the games used, we classify the reviewed papers into papers that use non-cooperative or cooperative games, simultaneous or sequential games, discrete or continuous games, and non-zero-sum or zero-sum games. Similarly, papers are also classified into two-player, three-player or multi-player game based papers. We also explore the nature of players and the construction of payoff functions in each scenario. Finally, we also identify gaps in literature where game theory could be fruitfully applied in scenarios hitherto unexplored using game theory. The presented analysis provides a concise summary of the state-of-the-art with regards to the use of game theory in defence applications and highlights the benefits and limitations of game theory in the considered scenarios

Analysis of a Batch Adsorber Analogue for Rapid Screening of Adsorbents for Postcombustion CO2 Capture

A simplified proxy model based on a well-mixed batch adsorber for vacuum swing adsorption (VSA) based CO2 capture from dry post-combustion flue gas is presented. A graphical representation of the model output allows for the rationalization of broad trends of process performance. The results of the simplified model are compared with a detailed VSA model that takes into account mass and heat transfer, column pressure drop and column switching, in order to understand its potential and limitations. A new classification metric to identify whether an adsorbent can produce CO2 purity and recovery that meet current US Department of Energy (US-DOE) for post-combustion CO2 capture and to calculate the corresponding parasitic energy is developed. The model, which can be evaluated within a few seconds, showed a classification Matthew correlation coefficient of 0.76 compared to 0.39, the best offered by any traditional metric. The model was also able to predict the energy consumption within 15% accuracy of the detailed model for 83% of the adsorbents studied. The developed metric and the correlation are then used to screen NIST/ARPA-E database to identify promising adsorbents for CO2 capture applications.Fil: Balashankar, Vishal Subramanian. University of Alberta; CanadáFil: Rajagopalan, Ashwin Kumar. University of Alberta; CanadáFil: De Pauw, R.. Vrije Unviversiteit Brussel; BélgicaFil: Avila, Adolfo María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaFil: Rajendran, Arvind. University of Alberta; Canad

Predictors of cognitive changes in patients with schizophrenia undergoing electroconvulsive therapy

Introduction: Previous studies on the effects of electroconvulsive therapy (ECT) on cognition in schizophrenia have been inconclusive. This study aimed to identify factors that may predict cognitive improvement or deterioration in patients with schizophrenia after-ECT. Materials & methods: Patients with schizophrenia or schizoaffective disorder with predominantly positive psychotic symptoms, who were treated with ECT at the Institute of Mental Health (IMH), Singapore, between January 2016 and January 2018, were assessed. Montreal Cognitive Assessment (MoCA), Brief Psychiatric Rating Scale (BPRS) and Global Assessment of Function (GAF) were performed before and after ECT. Patients with clinically significant improvement, deterioration or no change in MoCA scores were compared on demographics, concurrent clinical treatment and ECT parameters. Results: Of the 125 patients analysed, 57 (45.6%), 36 (28.8%) and 32 (25.6%) showed improvements, deterioration and no change in cognition respectively. Age and voluntary admission predicted MoCA deterioration. Lower pre-ECT MoCA and female sex predicted MoCA improvement. Patients showed improvements in GAF, BPRS and BPRS subscale scores on average, except for the MoCA deterioration group, who did not show statistically significant improvement in negative symptom scores. Sensitivity analysis showed that nearly half the patients (48.3%) who were initially unable to complete MoCA pre-ECT were able to complete MoCA post-ECT. Conclusions: The majority of patients with schizophrenia demonstrate improved cognition with ECT. Patients with poor cognition pre-ECT are more likely to see improvement post-ECT. Advanced age may be a risk factor for cognitive deterioration. Finally, improvements in cognition may be associated with improvements in negative symptoms.Published versio