Guidance and Control strategies for aerospace vehicles

A neighboring optimal guidance scheme was devised for a nonlinear dynamic system with stochastic inputs and perfect measurements as applicable to fuel optimal control of an aeroassisted orbital transfer vehicle. For the deterministic nonlinear dynamic system describing the atmospheric maneuver, a nominal trajectory was determined. Then, a neighboring, optimal guidance scheme was obtained for open loop and closed loop control configurations. Taking modelling uncertainties into account, a linear, stochastic, neighboring optimal guidance scheme was devised. Finally, the optimal trajectory was approximated as the sum of the deterministic nominal trajectory and the stochastic neighboring optimal solution. Numerical results are presented for a typical vehicle. A fuel-optimal control problem in aeroassisted noncoplanar orbital transfer is also addressed. The equations of motion for the atmospheric maneuver are nonlinear and the optimal (nominal) trajectory and control are obtained. In order to follow the nominal trajectory under actual conditions, a neighboring optimum guidance scheme is designed using linear quadratic regulator theory for onboard real-time implementation. One of the state variables is used as the independent variable in reference to the time. The weighting matrices in the performance index are chosen by a combination of a heuristic method and an optimal modal approach. The necessary feedback control law is obtained in order to minimize the deviations from the nominal conditions

Evaluating the rural health placements of the Rural Support Network at the Faculty of Health Sciences University of Cape

Objectives: The Rural Support Network (RSN) is an undergraduate student society that aims to raise awareness among the student body of the plight of rural health in South Africa, and organises individual and group placements in rural hospitals during vacations. This research aimed to evaluate these placements from the students' perspectives. Design: In-depth, face-to-face interviews were conducted with 10 students and nine placement-reflective reports were reviewed. The data were analysed and coded for key themes using a constant, comparative grounded theory approach. Setting: Faculty of Health Sciences (FHS) at the University of Cape Town. Subjects: Students who had been on RSN placements in 2010. Results: Students reported that the experience exceeded their expectations of learning new skills and observing and performing procedures. They gained significant insights into rural health care and were inspired to contribute to rural health in future. Their experiences helped them to gain confidence and an appreciation of the psycho-social aspects of patient care. The importance of community empowerment and of connecting and building relationships with communities was also emphasised. Challenges pertained to conflict within groups, incidents of unprofessional health care and being unable to help as much as they would have liked. Conclusion: The study highlights the impact that positive experiences of rural health may have on health science students' interest in, passion for, and commitment to practising in underserved rural areas. Students' key recommendations for the FHS included the development of a rural programme within the undergraduate curriculum. Better group composition and improved planning and co-ordination of placements by the RSN were also recommended

Do electronic patient information systems improve efficiency and quality of care? An evaluation of utilisation of the Discovery HealthID application

Background. Electronic health records (EHRs) appear to offer a number of potential benefits, but practitioners are often hesitant to make the transition to using them.Objectives. To determine whether the use of one such system, designed and offered by a health insurer (HealthID; Discovery Health), makes a difference to the efficiency and quality of doctor-patient consultations.Methods. A descriptive study using mixed methods was designed. A qualitative phase of individual interviews of purposefully sampled respondents was followed by a quantitative survey of a random sample of general practitioners and specialists who were registered users of the system.Results. In the qualitative findings, 18 respondents reported their perceptions of the ease of use of the application, their motivation for using it, its functions and benefits, the impact on efficiency and quality of care, and the challenges they experienced. In addition, they reported on the details of the challenges of using the system, and made suggestions for improvements, particularly with regard to the need for training and IT support. The quantitative results from the majority of 93 respondents confirmed that while the use of the app improved patient care through positive effects on specific functions such as access to accurate patient records and easier Chronic Illness Benefit applications, they felt that it had an equivocal impact in other areas, such as maintaining patient confidentiality and enhancing teamwork and efficiency. The financial incentives offered by Discovery Health, as well as possibly the training and support provided, appear to be more influential for high-frequency than for low-frequency users. The majority said that it did not help with referrals or script writing, or with access to International Statistical Classification of Diseases and Related Health Problems, 10th revision (ICD-10) codes.Conclusions. EHR systems like Discovery Health’s HealthID could improve the efficiency of medical consultations by increasing access to stored health information without requiring data entry by clinicians, and thereby have the potential to indirectly improve the quality of care, provided that certain conditions are met.

Case studies to enhance online student evaluation: Bond University – Surveying students online to improve learning and teaching

One of the most sensible ways of improving learning and teaching is to ask the students for feedback. At the end of each teaching period (i.e. semester or term) all universities and many schools survey their students. Usually these surveys are managed online. Questions ask for student perceptions about teaching, assessment and workload. The survey administrators report four common problems

FORMULATION AND EVALUATION OF SIMVASTATIN GASTRORETENTIVE DRUG DELIVERY SYSTEM

Objective: The aim of this study was to formulate and evaluate gastro retentive drug delivery system (GRRDS) using an effervescent approach for simvastatin.Methods: Floating tablets were prepared using directly compressible polymers hydroxypropyl methylcellulose (HPMC) K100M, HPMC K4M and carboxymethylcellulose sodium (NaCMC). The prepared tablets were subjected to pre-formulation studies like Compressibility index, Hausner ratio and post compression parameters like buoyancy/floating test and In vitro dissolution study.Results: Drug-excipient compatibility studies performed with the help of FTIR instrument indicated that there were no interactions. The DSC thermogram of the formulations revealed that crystalline form of simvastatin existed in the formulation which was confirmed by X-ray powder diffraction. Dissolution studies indicated that there was a decrease in the drug release with an increase in the polymer viscosity. The tablets prepared with low-viscosity grade HPMC K4M exhibited short Buoyancy Lag Time and floated for a longer duration as compared with formulations containing high viscosity grade HPMC K100M. The ‘n' value for dissolution studies for all the formulations was found to be in the range of 0.647 to 0.975 indicating non-Fickian or anomalous drug transport. Conclusion: The drug release rate and floating duration of tablets depended on the nature of the polymer and other added excipients. The release rate of the drug can be optimized by using different ratios of polymers and other excipients. The formulation F8 achieved the optimized batch and complied with all the properties of the tablets

Postmastectomy chest wall radiation of left-sided carcinoma breast - a dosimetric comparison between electrons and photons

Background: For carcinoma breast patients requiring post mastectomy radiation therapy (PMRT), tangential photon beam (PB) is commonly used technique. The physical nature of electrons results in sharp dose fall off and reduces organs at risk (OAR) doses. Aim of the present study is to compare the coverage of chest wall and doses received by OARs – heart and lung between electron and photon beam plans in left sided breast cancer patients requiring PMRT.Methods: This study was done in 22 left sided carcinoma breast patients treated at GSL Medical College between May to December 2017. Both tangential PB plans and electron beam (EB) plans were generated on simulation computed tomography (CT) for each patient and both plans were compared. A dose of 50 Gy was prescribed to planning target volume (PTV) in 25 fractions.Results: The PB plans provided superior homogeneity index (HI) and conformity index CI compared to the EB plans (p<0.05). There was significant difference in favour of electron-beam plans for mean heart dose (p=0.0312), V25 Gy (p=0.029), V45 Gy (p=0.001) and V20 Gy of left lung (p=0.042). There was no significant difference in mean lung dose.Conclusions: Dosimetric data from this study suggests that PMRT with the electron beam can reduce doses to the heart and left lung with acceptable target coverage. It needs further research in the clinical setting

Early warning system for shallow landslides using rainfall threshold and slope stability analysis

A combined cluster and regression analysis were performed for the first time to identify rainfall threshold that triggers landslide events in Amboori, Kerala, India. Amboori is a tropical area that is highly vulnerable to landslides. The 2, 3, and 5-day antecedent rainfall data versus daily rainfall was clustered to identify a cluster of critical events that could potentially trigger landslides. Further, the cluster of critical events was utilized for regression analysis to develop the threshold equations. The 5-day antecedent (x-variable) vs. daily rainfall (y-variable) provided the best fit to the data with a threshold equation of y = 80.7–0.1981x. The intercept of the equation indicates that if the 5-day antecedent rainfall is zero, the minimum daily rainfall needed to trigger the landslide in the Amboori region would be 80.7 mm. The negative coefficient of the antecedent rainfall indicates that when the cumulative antecedent rainfall increases, the amount of daily rainfall required to trigger monsoon landslide decreases. The coefficient value indicates that the contribution of the 5-day antecedent rainfall is ∼20% to the landslide trigger threshold. The slope stability analysis carried out for the area, using Probabilistic Infinite Slope Analysis Model (PISA-m), was utilized to identify the areas vulnerable to landslide in the region. The locations in the area where past landslides have occurred demonstrate lower Factors of Safety (FS) in the slope stability analysis. Thus, rainfall threshold analysis together with the FS values from slope stability can be suitable for developing a simple, cost-effective, and comprehensive early-warning system for shallow landslides in Amboori and similar regions

Lagrangian subcategories and braided tensor equivalences of twisted quantum doubles of finite groups

We classify Lagrangian subcategories of the representation category of a twisted quantum double of a finite group. In view of results of 0704.0195v2 this gives a complete description of all braided tensor equivalent pairs of twisted quantum doubles of finite groups. We also establish a canonical bijection between Lagrangian subcategories of the representation category of a twisted quantum double of a finite group G and module categories over the category of twisted G-graded vector spaces such that the dual tensor category is pointed. This can be viewed as a quantum version of V. Drinfeld's characterization of homogeneous spaces of a Poisson-Lie group in terms of Lagrangian subalgebras of the double of its Lie bialgebra. As a consequence, we obtain that two group-theoretical fusion categories are weakly Morita equivalent if and only if their centers are equivalent as braided tensor categories.Comment: 26 pages; several comments and references adde

Clonazepam induced maculopapular rash: a case report

Clonazepam is a benzodiazepine with prominent anticonvulsant action than other members of the group at equisedating doses. It especially blocks pentylenetetrazole-induced seizures. Other important actions include anxiolysis. Common adverse effects to Clonazepam include drowsiness and lethargy. In this submission we report a case of Clonazepam induced maculopapular rash in a 30 year old female treated for panic disorder

Creep stability of the proposed AIDA mission target 65803 Didymos: I. Discrete cohesionless granular physics model

As the target of the proposed Asteroid Impact & Deflection Assessment (AIDA) mission, the near-Earth binary asteroid 65803 Didymos represents a special class of binary asteroids, those whose primaries are at risk of rotational disruption. To gain a better understanding of these binary systems and to support the AIDA mission, this paper investigates the creep stability of the Didymos primary by representing it as a cohesionless self-gravitating granular aggregate subject to rotational acceleration. To achieve this goal, a soft-sphere discrete element model (SSDEM) capable of simulating granular systems in quasi-static states is implemented and a quasi-static spin-up procedure is carried out. We devise three critical spin limits for the simulated aggregates to indicate their critical states triggered by reshaping and surface shedding, internal structural deformation, and shear failure, respectively. The failure condition and mode, and shear strength of an aggregate can all be inferred from the three critical spin limits. The effects of arrangement and size distribution of constituent particles, bulk density, spin-up path, and interparticle friction are numerically explored. The results show that the shear strength of a spinning self-gravitating aggregate depends strongly on both its internal configuration and material parameters, while its failure mode and mechanism are mainly affected by its internal configuration. Additionally, this study provides some constraints on the possible physical properties of the Didymos primary based on observational data and proposes a plausible formation mechanism for this binary system. With a bulk density consistent with observational uncertainty and close to the maximum density allowed for the asteroid, the Didymos primary in certain configurations can remain geo-statically stable without including cohesion.Comment: 66 pages, 24 figures, submitted to Icarus on 25/Aug/201