Combined monitoring, decision and control model for the human operator in a command and control desk

A report is given on the ongoing efforts to mode the human operator in the context of the task during the enroute/return phases in the ground based control of multiple flights of remotely piloted vehicles (RPV). The approach employed here uses models that have their analytical bases in control theory and in statistical estimation and decision theory. In particular, it draws heavily on the modes and the concepts of the optimal control model (OCM) of the human operator. The OCM is being extended into a combined monitoring, decision, and control model (DEMON) of the human operator by infusing decision theoretic notions that make it suitable for application to problems in which human control actions are infrequent and in which monitoring and decision-making are the operator's main activities. Some results obtained with a specialized version of DEMON for the RPV control problem are included

Closed loop models for analyzing the effects of simulator characteristics

The optimal control model of the human operator is used to develop closed loop models for analyzing the effects of (digital) simulator characteristics on predicted performance and/or workload. Two approaches are considered: the first utilizes a continuous approximation to the discrete simulation in conjunction with the standard optimal control model; the second involves a more exact discrete description of the simulator in a closed loop multirate simulation in which the optimal control model simulates the pilot. Both models predict that simulator characteristics can have significant effects on performance and workload

Closed loop models for analyzing engineering requirements for simulators

A closed loop analytic model, incorporating a model for the human pilot, (namely, the optimal control model) that would allow certain simulation design tradeoffs to be evaluated quantitatively was developed. This model was applied to a realistic flight control problem. The resulting model is used to analyze both overall simulation effects and the effects of individual elements. The results show that, as compared to an ideal continuous simulation, the discrete simulation can result in significant performance and/or workload penalties

Tensile and Compressive Constitutive Response of 316 Stainless Steel at Elevated Temperatures

Creep rate in compression is lower by factors of 2 to 10 than in tension if the microstructure of the two specimens is the same and are tested at equal temperatures and equal but opposite stresses. Such behavior is characteristic for monotonic creep and conditions involving cyclic creep. In the latter case creep rate in both tension and compression progressively increases from cycle to cycle, rendering questionable the possibility of expressing a time stabilized constitutive relationship. The difference in creep rates in tension and compression is considerably reduced if the tension specimen is first subjected to cycles of tensile creep (reversed by compressive plasticity), while the compression specimen is first subjected to cycles of compressive creep (reversed by tensile plasticity). In both cases, the test temperature is the same and the stresses are equal and opposite. Such reduction is a reflection of differences in microstructure of the specimens resulting from different prior mechanical history

Custom-Designed HI-V Semiconductor Mimstmctures Wed to the Ultimate Physical Limit : U I ~ - L a y e r GaAs/AUs ~uperhtticesa nd Delta- (Monolayer) Doping in GaAs/Al,Ga,-As Structures

Two prototype artificially-layered semiconductor structures are presented in which the concept of microscopical structuring of solids is scaled to its ultimate physical limit normal to the crystal surface. In both the(G~AS),/(AIASm)~o no layer superlattice and in the delta- (or monolayer)doped G~AS/AI~G~,-s~truAcStu res, which have been grown by molecular beam epitaxy, the characteristic material lengths have reached a spatialextent nornlal to the surface of less than the lattice constant. The (GaAs),/(AIAs), ultrathin-layer superlattices exhibit novel optical properties due tothe indirect-gap nature ofthe constituent AlAs layers. The minority-carrier lifetimes can be tailored over four orders of magnitude by appropriately designing the superlattice configuration. This feature opens up new fieldsof application in lasers and in nonlinear photonic and optoelectronic devices. The narrow buried doping channel in delta-doped GaAslayers andin GaAs/AI,Gal-xAs structures leads to a significant improvement of the electrical properties. Based on this concept, non alloyed ohmic contacts,field-effect transistors with ;cry high transconductance, unpinned GaAs surfaces for MOS devices, and electron mobilities as high as 10' cm2v-'s-Ihave been fabricated

Detecting mutations in mixed sample sequencing data using empirical Bayes

We develop statistically based methods to detect single nucleotide DNA mutations in next generation sequencing data. Sequencing generates counts of the number of times each base was observed at hundreds of thousands to billions of genome positions in each sample. Using these counts to detect mutations is challenging because mutations may have very low prevalence and sequencing error rates vary dramatically by genome position. The discreteness of sequencing data also creates a difficult multiple testing problem: current false discovery rate methods are designed for continuous data, and work poorly, if at all, on discrete data. We show that a simple randomization technique lets us use continuous false discovery rate methods on discrete data. Our approach is a useful way to estimate false discovery rates for any collection of discrete test statistics, and is hence not limited to sequencing data. We then use an empirical Bayes model to capture different sources of variation in sequencing error rates. The resulting method outperforms existing detection approaches on example data sets.Comment: Published in at http://dx.doi.org/10.1214/12-AOAS538 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Simulation of an Armoured Vehicle for Blast Loading

Occupant safety in an armoured vehicle is of paramount importance. Most serious threat to armoured vehicles comes in the form of explosion of buried charge or an improvised explosive device. The use of numerical methods in the validation process of light armoured vehicles reduces the number of prototypes required and decreases the design time. This paper elucidates the process by which one such validation using numerical methods was done. The process of finite element method used for simulation of blast is a prominent method of numerical method of simulation. The finite element model (FEM) process starts with discretisation. By discretisation or meshing, Shell (Quad/Tria) and solid (Tetra/Hexa) elements are generated. The FEM thus created is provided with relevant material model / properties and loading and boundary conditions. The loading conditions are adopted from STANAG 4569 Level II standards. Local deformation, global displacement, stresses and time history of displacement of particular areas of interest are obtained as results. Comparison results include the effect of with and without thermal softening under blast. Based on the results and comparison, suggestions regarding re-engineering the vehicle are presented

Plants used for topical application from Gingee hills, Tamil Nadu, India.

This study is a documentation of medicinal plants used for topical applications by villagers around Gingee hills of Villupuram District, Tamil Nadu, India. A total of 23 Dicot plants belong to 18 families are used as topical applications to treat various skin diseases such as sore, psoriasis, itching, scabies, eczema and other skin infections. Herbs (8 species) are the dominant life form category equal number of shrubs and trees (6 species) followed by 3 species of climbers. Generally fresh plant parts are used in the form of powder, extract and paste. Leaves are the mostly used part in the preparation of medicine. The present study concluded that the abundance of medicinally important plants is an excellent potential for discovery of novel drugs to cure various ailments

Investigation of the Performance and Emission Characteristics of Ceiba Pentandra Biodiesel Blends in a Variable Compression Ratio Engine

In the current scenario, the production of biodiesel from non-edible oil is a promising way to overcome the problems associated with the energy crisis and environmental issues. In this research, non-edible biodiesel blends of B10, B20, B30, B40, and B100 methyl esters of Ceiba pentandra oil with standard diesel fuel are used to investigate the performance, combustion and emission characteristics of a variable compression ratio engine at different load conditions compared to diesel. The compression ratios 16.5:1, 17.5:1, 18.5:1 are employed in a 1500 rpm constant speed, single-cylinder with a variable compression ratio, direct injection, four-stroke diesel engine for experimental investigation. Performance and combustion characteristics such as brake specific energy consumption, brake thermal efficiency, net heat release rate and emission characteristics such as carbon monoxide, carbon dioxide, hydrocarbons and oxides of nitrogen are investigated. The biodiesel blend B10 and B20 showed optimal performance with fewer emissions