Analysis of a VTOL hover task with predictor displays using an optimal control model of the human operator

The influence of different types of predictor displays in a longitudinal VTOL hover task is analyzed in a theoretical study. It was assumed that pitch angle and position are presented to the pilot in separate displays namely the artificial horizon and position display. The predictive information is calculated by means of a Taylor series. From earlier experimental studies it is well known that predictor displays improve human and system performance and result in reducing human workload. In this study, an optimal control model is used to prove this effect theoretically. Several cases with differing amounts of predictive and rate information are compared

Modeling the human as a controller in a multitask environment

Modeling the human as a controller of slowly responding systems with preview is considered. Along with control tasks, discrete noncontrol tasks occur at irregular intervals. In multitask situations such as these, it has been observed that humans tend to apply piecewise constant controls. It is believed that the magnitude of controls and the durations for which they remain constant are dependent directly on the system bandwidth, preview distance, complexity of the trajectory to be followed, and nature of the noncontrol tasks. A simple heuristic model of human control behavior in this situation is presented. The results of a simulation study, whose purpose was determination of the sensitivity of the model to its parameters, are discussed

Labour Demand and Labour-saving Options: A Case of Groundnut Crop in India

Groundnut is a labour-intensive crop, especially for operations like sowing, weeding, harvesting, and drying. But, of-late, due to timely unavailability of labour, many farmers are not able to exercise timely operations resulting in low yield realization. The present study conducted in two major groundnut-growing states, viz. Gujarat and Andhra Pradesh, has revealed that farmers employ more human labour in weeding and harvesting operations in groundnut than in other operations. The practise of manual decortication and stripping is followed by a larger number of farmers in Andhra Pradesh than in Gujarat, indicating less mechanization in the former. For weeding, though, the human labour-use in weedicide + bullock intercultivation + hand weeding technique is almost half of that of the bullock inter-cultivation + hand weeding, only 13 per cent of the farmers practise this labour-saving technique and hence this method should be disseminated in both the regions to reduce human-labour demand. In Andhra Pradesh, for all the operations in groundnut cultivation except harvesting, the cost as well as labour-use has been reduced substantially due to use of partial/complete mechanization methods. Hence, the necessary infrastructure (labour-saving machineries) should be created at the village or block level to reduce the human-labour demand.Labour demand, Groundnut cultivation, Labour-saving techniques, Agricultural and Food Policy, J23, J21,

The human as a detector of changes in variance and bandwidth

The detection of changes in random process variance and bandwidth was studied. Psychophysical thresholds for these two parameters were determined using an adaptive staircase technique for second order random processes at two nominal periods (1 and 3 seconds) and damping ratios (0.2 and 0.707). Thresholds for bandwidth changes were approximately 9% of nominal except for the (3sec,0.2) process which yielded thresholds of 12%. Variance thresholds averaged 17% of nominal except for the (3sec,0.2) process in which they were 32%. Detection times for suprathreshold changes in the parameters may be roughly described by the changes in RMS velocity of the process. A more complex model is presented which consists of a Kalman filter designed for the nominal process using velocity as the input, and a modified Wald sequential test for changes in the variance of the residual. The model predictions agree moderately well with the experimental data. Models using heuristics, e.g. level crossing counters, were also examined and are found to be descriptive but do not afford the unification of the Kalman filter/sequential test model used for changes in mean

Impact of Grain Legume (Groundnut) on Energy and Nutritional Levels of Tribal Farm Households in Koraput (Orissa)

The introduction of groundnut through the support of IFAD & ICRISAT in the tribal areas of Koraput in Orissa has been able to supplement the nutritional levels of farm households in the area. The protein intake due to groundnut consumption has been found to be around 20 per cent in the IFAD participants and 11 per cent in the non-participants. The study has observed a perceptible contribution of groundnut (grain legume) in meeting the protein and energy needs of the tribal farm households in the study area. Further, groundnut has been found as the cheapest source of protein and energy among different food items like fish, meat, egg, etc., consumed by the tribal households. This low-cost energy-rich grain legume (groundnut) may be popularised to increase the frequency and quantity of intake to achieve nutritionally secured human resource (tribal people). This strategy will also enhance the sustainable crop production due to inherent advantage of legumes in the cropping system like soil health improvement, low external input addition, atmospheric nitrogen fixation by beneficial microorganisms and reduced soil and environmental pollution.Crop Production/Industries, Food Security and Poverty,