Conceptual design study of advanced acoustic composite nacelle

Conceptual nacelle designs for wide-bodied and for advanced-technology transports were studied with the objective of achieving significant reductions in community noise with minimum penalties in airplane weight, cost, and in operating expense by the application of advanced composite materials to nacelle structure and sound suppression elements. Nacelle concepts using advanced liners, annular splitters, radial splitters, translating centerbody inlets, and mixed-flow nozzles were evaluated and a preferred concept selected. A preliminary design study of the selected concept, a mixed flow nacelle with extended inlet and no splitters, was conducted and the effects on noise, direct operating cost, and return on investment determined

Identification of unknowns within a probabilistic system: The diagnostic value of attributes

Using a data base underpinned by probability considerations in which a variety of attributes, some of which may be quantitative, are recorded for a number of “operational taxonomic units” (OTUs), a key system is described by which an unnamed specimen may quickly be identified. The concept of “diagnostic power” is introduced, by which each attribute is evaluated in terms of its potential contribution to identifying the unnamed specimen. Besides coverage of different types of attributes and the introduction of “diagnostic power”, the system has the advantages of incorporating multiple values of an attribute for each OTU and offering short-cuts to identification

Study of Leishmaniasis as it occurs in India

Descriptions of 10 cases of Kala azar, 1 case of cutaneous Leishmaniasis, and 64 cases of Oriental Sore are given. These are all cases which have been for some time under my personal care or observation. During my service at Chittagong, however, I had almost daily opportunity of seeing several fresh cases as out -patients or as patients in. the Civil Hospital or Assam -Bengal Railway Hospital and this experience has influenced my conclusions. `I. KALA AZAR. (1) Kala azar has a wider distribution than is generally believed. I have seen cases in Dehra Dun in the Western United Provinces which is a semi hill station. Judging from the number of cases occurring in Gurkhas on return from furlough it seems more than probable that this disease occurs in Nepal. (2) Certain symptoms and signs appear to be overrated and others not given sufficient prominence. The 'double remittent' type of fever is more often than not absent. In my series of cases only two demonstrate this feature, and I have seen it present in other diseases e.g. tuberculosis. The Chief Medical Officer of the Assam-Bengal Railway and the Civil Surgeon Chittagong who both treat very large numbers of Kala azar patients put very little reliance on this symptom. Pigmentation is another sign which is not reliable. It is hard to make it out in a dark-skinned individual and is very often present in malarial cachexia. A clean tongue was almost invariably present in all the cases which I examined. A feature which is seldom mentioned is the brittle state of most Kala azar patients' hair. In many cases it tends to fall out, especially in women. (3) The importance of full examination of the blood cannot be emphasised too much. The principal points to note are the marked leucopenia, the reduction in proportion of polymorphs and relative increase in mononuolears and lymphocytes. The proportion of whites to reds should always be estimated. The .r proportion as generally quoted is 1 white to 1500 reds. In my experience it is even less. Eosinophils are often absent but associated worm infections cause them to appear in quite considerable numbers. (4) Present day treatment of Kala azar in India is not as thorough as it should be. The majority of large hospitals favour the rapid method of injections. The patient, too, is not admitted to hospital as a rule unless complications are present. The result is that the patient ceases to attend and only received a sufficient number of injections to improve but not to cure his condition. This leads to relapses and I believe to increased incidence of dermal leishmaniasis. Whenever possible the patient should be kept in bed and given intravenous injections of neostibosan or urea stibamine every second or third day until at least fifteen injections have been administered. Nourishing diets rich in vitamins should be given. This prolongs the period of treatment but produces a cure rather than a temporary improvement. (5) Judging from the number of admissions nowadays as compared with ten years ago the disease appears to be decreasing.II. KALA AZAR WITH CAPTCRUM ORIS . (1) This is a common and serious complication of Kala azar. Although quite often seen in adults it is four times as common in children in whom it is present in about 12 per cent of cases. (2) Canerum oris is not due to the presence of Leishmania donovani in Kala azar patients. In spite of careful examination no Leishmania were seen in scrapings taken from the lesions though mixed infections were common. It is due to the same causes which produce this condition in other diseases e.g. diphtheria, measles, typhoid etc. Probably lowered resistance due to prolonged fever allows the bacteria normally present in the mouth to erode and invade the tissues of the mouth and face. (3) Blood counts show certain constant features. The white blood corpuscles are increased in number to between 7,000 and 16,000 per c.mm. The increase in leucocytes is due to the increase in polymorphonuclea:rs. The haemoglobin is reduced. (4) The prognosis in C ancrum oris is bad. The majority of cases die in a few weeks from toxaemia or intercurrent infection. Those in hospital often show a marked improvement under treatment but do not remain long enough to reap the full benefit. (5) The most effective treatment consists in intramuscular injections of neostibosan in children, and intravenous injections of urea stibomine in adults. Extensive erosions should be treated with skin grafts once the ulceration has become as nearly as possible aseptic.III. DERMAL LEISHMANIASIS. (1) This is a much commoner disease than the number of hospital admissions would lead one to believe. Now that the disease is better known more patients are coming for treatment. (2) The disease can easily be mistaken for leprosy and unless scrapings are examined from the lesions many patients will be wrongly diagnosed. Owing to the much more favourable prognosis in dermal leishmaniasis this mistake should be carefully guarded against. (3) The chronic nature of the disease and the large number of injections which are often required to effect a cure should be carefully noted. Treatment will always be successful even in the most stubborn cases if persisted in. (4) There is always the danger of spread of Kala azar by means of sandflies feeding on these lesions. It is a danger to the public therefore to allow those patients to go about untreated.IV. ORIENTAL SORE. (1) Oriental sore is caused by a leishmania closely allied to Leishmania donovani but less virulent and only capable of producing skin lesions. It is transmitted by a sandfly which is distinct from the sandfly transmitting Kala azar, and this sandfly is only capable of transmitting Leishmania tropics,. (2) Each bite of an infected sandfly produces a sore at the area bitten. It is not a systemic disease whereas Kala azar is a systemic disease. (3) Antimony in either its trivalent or pentavalent form is the most effective and cheapest drug in the treatment of Oriental sores. The dose of potassium antimony tartrate should be regulated according to the weight of the patient and in any case should never exceed gr.2 at one time. It must be carefully injected to the sloughing it causes if allowed to escape into the tissues. If an accident of this kind does occur then iodex is a useful application and gives some relief. Neostibosan is expensive but is not so liable to cause sore arms or sloughing. (4) In chronic cases emetine hydrochloride gr.0.5 to gr.1 injected into the margins of the sores hastens the healing process produced by the antimony. This treatment is however rather painful. (5) Orisol (berberine sulphate) was not so successful as one might expect from the results claimed for. it. For single sores or small lesions before they have broken down, this drug gives good results. This latter conclusion was also arrived at by Napier (Knowles (68)) some years ago. Results with large or multiple sores are almost always disappointing. (6) Local dressings play a very important part in the rapidity of cure. There were many examples of patients who kept their dressings and sores clean and healing occurred in from three to six weeks. There were many examples of others who were careless or ignorant and allowed their sores to become secondarily infected. They then took even as long as four months to cure. Normal saline is a very satisfactory dressing - followed by iodine once healing has started. (7) Early treatment is most essential. The old-standing case is hard to cure: the recently developed case is comparatively easy to cure. (8) The total dosage of antimony required to effect a cure can be reduced by the use of supplementary emetine or orisol and rigid local treatment

Approximate Shielding of Atari Agents for Safe Exploration

Balancing exploration and conservatism in the constrained setting is an important problem if we are to use reinforcement learning for meaningful tasks in the real world. In this paper, we propose a principled algorithm for safe exploration based on the concept of shielding. Previous approaches to shielding assume access to a safety-relevant abstraction of the environment or a high-fidelity simulator. Instead, our work is based on latent shielding - another approach that leverages world models to verify policy roll-outs in the latent space of a learned dynamics model. Our novel algorithm builds on this previous work, using safety critics and other additional features to improve the stability and farsightedness of the algorithm. We demonstrate the effectiveness of our approach by running experiments on a small set of Atari games with state dependent safety labels. We present preliminary results that show our approximate shielding algorithm effectively reduces the rate of safety violations, and in some cases improves the speed of convergence and quality of the final agent.Comment: Accepted for presentation at the ALA workshop as part of AAMAS 202

Approximate Model-Based Shielding for Safe Reinforcement Learning

Reinforcement learning (RL) has shown great potential for solving complex tasks in a variety of domains. However, applying RL to safety-critical systems in the real-world is not easy as many algorithms are sample-inefficient and maximising the standard RL objective comes with no guarantees on worst-case performance. In this paper we propose approximate model-based shielding (AMBS), a principled look-ahead shielding algorithm for verifying the performance of learned RL policies w.r.t. a set of given safety constraints. Our algorithm differs from other shielding approaches in that it does not require prior knowledge of the safety-relevant dynamics of the system. We provide a strong theoretical justification for AMBS and demonstrate superior performance to other safety-aware approaches on a set of Atari games with state-dependent safety-labels.Comment: Accepted at ECAI 2023 (main technical track

Methods of social assessment in Marine Protected Area planning: Is public participation enough?

Addressing social and economic considerations is crucial to the success of Marine Protected Area (MPA) planning and management. Ineffective social assessment can alienate local communities and undermine the success of existing and future MPAs. It is rare to critique the success of methods used currently to incorporate social and economic considerations into MPA planning. Three Australian MPA planning processes covering three states and incorporating federal and state jurisdictions are reviewed in order to determine how potential social impacts were assessed and considered. These case studies indicate that Social Impact Assessment (SIA) is under-developed in Australian MPA planning. Assessments rely heavily on public participation and economic modelling as surrogates for dedicated SIA and are followed commonly by attitudinal surveys to gauge public opinion on the MPA after its establishment. The emergence of issues around public perception of the value of MPAs indicates the failure of some of these proposals to adequately consider social factors in planning and management. This perception may have potential implications for the long term success of individual MPAs. It may also compromise Australia's ability to meet international commitments for MPA targets to gazette at least 10% of all its marine habitats as MPAs. Indeed, this is demonstrated in two of the three case studies where social and economic arguments against MPAs have been used to delay or block the future expansion of the MPA network. © 2011 Elsevier Ltd