FUZZY-GENETIC ALGORITHMS AND TIME-OPTIMAL OBSTACLE-FREE PATH GENERATION FOR MOBILE ROBOTS

This paper, describes a new yet efficient technique based on fuzzy logic and genetic algorithms (Gas) to solve the find-path problems of a mobile robot, which is formulated as a nonlinear programming problem. In the proposed algorithm, a fuzzy logic controller is used to find obstracle-free directions locally and GAs are used as optimizer to find optimal/near-optimal locations along the obstracle-free directions. This algorithm is found to be more efficient than a steepest gradient descent method. Although the fuzzy-GA method is shown to find slightly inferior or similar solutions to those found using the best-known tangent-graph and A* algorithms, it is computationally faster than them. Moreover, the fuzzy-GA approach is practically more viable than the tangent-graph method, because of former's lesser sensitivity to the number and type of obstacles. The efficiency of the proposed method demonstrated in this paper suggests that it can be extended to solve motion planning problems having moving obstacles.     

Physiological cost of work under hot dry climates in Indian industries An analysis

The possibility of using pulse rate during work as a measure of the energy coat of that work, in lieu of the more cumbersome gas analysis techniques, has been examined in actual industrial environments for varied work and thermal loads. Three sets of data from some hot dry industries situated in different parts of India were analysed : (a) extreme levels ; (b) moderate levelB ; and (c) comparatively low levels of work and heat loads. Pulse rate (PR) measurements, in conjunction with body surface area (BSA) and corrected effective temperature (CET) were found to be significantly correlated with energy expenditure (EE) at both high and moderate levels (τ = 0-889 and 0-902, respectively); the predictive ability of the corresponding regression coefficients was also high (SE of estimate—± 10%).

PR was also found to bear a linear relationship with work load at various levels of heat stress. Further, it was evident that at all levels (a), (b) and (c), the effect of work effort on observed pulse rate was more significant than that of heat exposure during work in hot environments.

From the observed relationships between PR, CET and BSA, on the one hand, and EE, on the other, it could be suggested that it is possible to predict the physiological cost of work from easily measurable parameters on the shop floor.     

Project Indravati: Phase I. An appraisal of the natural resources of the Indravati basin,Orissa, Madhya Pradesh and Maharashtra,India

Project Indravati has been taken up to demonstrate the capabilities of remote-sensing data for the exploration of natural resources and also the structural linkages necessary to evolve a National Natural Resources Management System (NNRMS). The Geological Survey of India, the National Atlas and Thematic Mapping Organization and the Forest Survey of India are the collaborating agencies under this project. The National Bureau of Soil Survey and Land-use Planning has supplied data on soils of the area. This densely forested, undercultivated region with a relatively virgin status in mineral exploration offers ample scope for using remote-sensing techniques in evaluating its natural resource potential.

Data on geology, structure and lineaments, geomorphology, drainage, soil and vegetation were compiled and collated, based on visual interpretation of LANDSAT imagery. The area has a complex physiographic and geological history and varied soil types. Vegetation is mostly mixed deciduous types.

Two test areas, which are relatively remote and difficult to approach, have been selected for detailed aerial and multispectral scanner survey for the assessment of natural resources.     

Study of PBL dynamics over northern plains in fixing stack height of a super thermal power station

The Planetary Boundary Layer plays an important role in air pollution meteorology and in fixing the Stack height of major air-polluting industries, including the super thermal power plants. In India a super thermal power plant is being set up at Yamunanagar (30·1° N, 77·33 ° E) and it has been studied using an acoustic sounder with a stack height of 220?m which would be the optimum height to keep the physical stack above surface based inversions for 80 per cent of the time and the elevated inversions for 50 per cent of time above. However, the hot plume rise would inject any pollutants above the surface based inversions for 95 per cent of the time     

Numerical simulation and experiment of error field measurement using luminous trace of electron beam in SST-1

In contrast to the earlier experiments conducted in other machines,here,in SST-1 the error field measurement experiment is performed with a filled gas pressure ～8×10~(-4) mbar which helped to create a luminescent toroidal beam of electron path originated due to impact excitation and guided by the toroidal magnetic field.Beam path deviations are observed and recorded from radial and top ports using visible range cameras.Such creation and detection of the electron beam path differs from the earlier works where the gun emitted electron beam deviation in ultrahigh vacuum was detected on a collector-grid/fluorescent screen.In the present experiment,large beam deviations were observed.Later investigation of the experimental set-up reveals existence of a possible source of radial electric field in between the source and the vacuum vessel which are separately grounded.Thus,to understand the observed phenomena,experiments are numerically modeled with deviated TF coil set,PF coil set and the electron source location.A particle tracing code is used to follow the electron path in the magnetic field generated by the coil set of interest.Simulation results suggest that the large deviation corresponds to the E×B drifts and not due to the large field errors.Toroidally averaged field errors of the SST-1 TF coils at toroidal field of B_0=15 kG are negligibly small～B_0×10~(-6) or less,which should not adversely affect the plasma performance.     

INFLUENCE OF DIFFERENT FACTORS ON ACTIVITY AND STABILITY OF ß-GALACTOSIDASE FROM LACTOBACILLUS ACIDOPHILUS1

Eight Lactobacillus acidophilus strains were tested for β-galactosidase activity. The results show that β-galactosidase is an inducible enzyme in this organism. Wide variations in enzyme properties of the strains were observed. The temperature and pH optima of the enzymes were 40–45C and 6.5–7.0, respectively. At 0.1 mM concentration, the enzyme activity in strain 4495 was slightly stimulated by 2-mercaptoethanol, partially inhibited by EDTA but remained more or less unaffected with thiomersal and ascorbic acid. In contrast, all the modulators completely inhibited the enzyme activity in strain 301. The enzyme in strain 301 was stable for 80 min at 50C, whereas the activity in strain 4495 was completely lost in 40 min. However, the enzyme was stable over a pH range of 5.8–8.0 and up to 60 days at 4 ± 1C in both strains. The K_m values for β-galactosidase from both the strains were same, whereas V_max for the enzyme from strain 301 was about 2-fold higher than that of strain 4495.     

Assessing compressive strengths of mortar and concrete from digital images by machine learning techniques

Compressive strength is the most important metric of concrete quality. Various nondestructive and semi-destructive tests can be used to evaluate the compressive strength of concrete. In the present study, a new image-based machine learning method is used to predict concrete compressive strength, including evaluation of six different models. These include support-vector machine model and various deep convolutional neural network models, namely AlexNet, GoogleNet, VGG19, ResNet, and Inception-ResNet-V2. In the present investigation, cement mortar samples were prepared using each of the cement:sand ratios of 1:3, 1:4, and 1:5, and using the water:cement ratios of 0.35 and 0.55. Cement concrete was prepared using the cement:sand:coarse aggregate ratios of 1:5:10, 1:3:6, 1:2:4, 1:1.5:3 and 1:1:2, using the water:cement ratio of 0.5 for all samples. The samples were cut, and several images of the cut surfaces were captured at various zoom levels using a digital microscope. All samples were then tested destructively for compressive strength. The images and corresponding compressive strength were then used to train machine learning models to allow them to predict compressive strength based upon the image data. The Inception-ResNet-V2 models exhibited the best predictions of compressive strength among the models tested. Overall, the present findings validated the use of machine learning models as an efficient means of estimating cement mortar and concrete compressive strengths based on digital microscopic images, as an alternative nondestructive/semi-destructive test method that could be applied at relatively less expense.     

Transferability of specimen J–R curve to straight pipe with circumferential surface flaw

Specimen J–R curve is extensively used for structural integrity of large components. It is well known that J–R curve heavily depends on constraint level ahead of crack tip in remaining ligament. In earlier work, it was demonstrated that J–R curve from Three Point Bending (TPB) specimen is transferable to straight pipe with circumferential through wall crack. In this paper, the transferability of J–R curve is investigated from TPB specimen to pipe with circumferential surface crack. A 16 in. diameter pipe with circumferential surface crack and TPB specimen machined from same piping material (SA333Gr6 Steel) are tested. Consequently, 3D finite element analysis (FEA) has been performed on surface cracked pipe and TPB specimen. Crack‐initiation load is also predicted for surface cracked pipe by FEA and compared with experimental result. J–R curve is calculated for the pipe using experimental data, that is, load, load line displacement and crack growth. J–R curve of pipe is compared with TPB specimen and it is found that the pipe is predicting much higher J–R curve than TPB. This difference of J–R curve is investigated by evaluating stress triaxiality in remaining ligament for both cases. Stress triaxiality is quantified using triaxiality factor (h) ahead of crack tip for pipe and TPB specimen. It is found that the TPB specimen has considerably higher constraint level than pipe with surface crack, which is well supported by trend of J–R curves for specimen and pipe. A study has also been carried out to investigate the effect of internal pressure on the stress triaxiality. It is found that there is negligible difference in stress triaxiality because of internal pressure. The stress triaxiality is re‐established as a qualitative parameter to assess the transferability of J–R curve from specimen to component.     

Studies on Thermal Stratification Phenomenon in LH2 Storage Vessel

A study of convective heat transfer in a cryogenic storage vessel is carried out numerically and experimentally. A scaled down model study is performed using water as the model fluid in a rectangular glass tank heated from the sides. The convective flow and the resulting thermal stratification phenomenon in the rectangular tank are studied through flow visualization, temperature measurement, and corresponding numerical simulations. It is found that a vortex-like flow near the top surface leads to a well-mixed region there, below which the fluid is thermally stratified. In addition, in an attempt to simulate the actual conditions, a numerical study is performed on a cylindrical cavity filled with liquid hydrogen (LH₂) and heated from the sides. The results are compared with our model study with water, and the qualitative agreement is found to be good.     

SOME MULTI-OBJECTIVE APPROACHES TO DIAMOND DRESSING OPTIMIZATION

Five relatively recent multi-objective optimization techniques, namely, the minimum deviation; the min-max; the weighted min-max; the fuzzy linear programming and the compromise constraint methods are used to determine optimal dressing conditions in the case of diamond dressing. The two objectives considered are to minimize surface roughness and specific grinding energy which are in conflict with each other. A comparative study of the results obtained by using different multi-objective optimization techniques is made.