Research on the Application of GIS Technology Combined with RBFNN-GA Algorithm in the Delineation of Geological Hazard Prone Areas

With the rapid development of the economy and society, geological disasters such as landslides, collapses, and mudslides have shown an intensifying trend, seriously endangering the safety of people’s lives and property, and affecting the sustainable development of the economy and society. Aiming at the problems of merging different data layers and determining the weighting of data stacking in the statistical analysis model based on GIS technology in the evaluation of the risk of geological disasters, this study proposes a logistic regression model combined with the RBFNN-GA algorithm, that is, the determination of the occurrence of geological disasters. The fusion coefficient (CF value) with the RBFNN-GA algorithm model, and with the help of SPSS statistical analysis software, solves the problem of factor selection, heterogeneous data merging, and weighting of each data layer in the risk assessment. In the experimental stage, this study adopts the method of geological hazard certainty coefficients to carry out the sensitivity analysis of the geological hazards in the study area. Using homogeneous grid division, the spatial quantitative evaluation of the risk of geological disasters is realized, and at the same time, the results of the spatial quantitative evaluation of the risk of geological disasters are tested according to the latest landslide points in the region. The existing classification mainly depends on the acquisition of land use/cover information or the processing method of the acquired information, but the existing information acquisition will be limited by time, space, and spectral resolution. The results show that the number of landslide points per unit area in the extremely unstable zone and the unstable zone is 0.0395 points/km2 and 0.0251 points/km2, respectively, which is much higher than 0.0038 points/km2 in the stable zone, indicating the evaluation results and actual landslide conditions.

Drilling Across a Highly Unstable Zone in an Exploratory Well in South Mexico

The Comalcalco Fault is a regional discontinuity that can present highly unstable zones when crossing it or its influence zone. This instability can lead to notorious increase in drag forces, cavings, stuck pipe events and ultimately loss of sections or the well. In the 12 ¼" hole of this exploratory well, this fault was present and despite some of the wells in the field managed to cross it without consequences, the influence was more notorious, and the problems lead to catastrophic results. While drilling the 12 ¼" section, the team was able to drill up to 4368 m without any relevant problems. The fault was intersected and drilled pass to section TD with the previous casing shoe at 2966 m. However, when a trip to surface was necessary, abnormal drag forces that avoided further movement of the string were experienced. This event led to the loss of the section and the need to perform a sidetrack, right across the influence zone of the fault at 3200 m. The risk was reassessed, and numerous preventive and mitigation measures were put in place, including drilling the section with a 12 ¼" pilot bit, enlarging the pilot hole to 13 ½" to cover the influence zone and having a contingency plan to run the 11 ¾" liner. Additionally, the formations were reinforced through drilling fluids design, and drilling and tripping strategies were optimized to minimize zonal invasion and influence zone disturbances that could lead to additional cavings. After the successful sidetrack, the section was drilled to 3600 m, 200 m below the fault’s influence zone. Good ROPs and low levels of stick and slip were observed despite several reaming runs while drilling. The contingency liner was run to TD, achieving the objective of isolating the influence zone of the Comalcalco Fault. With the problematic zone placed behind pipes, drilling the remaining of the original 12 ¼" sections with a 10 5/8" × 12 ¼" reamer resulted in the longest and fastest enlarged section to be realized in the field. With all the preventive measures put in place, the original 9 5/8" casing was set at its planned depth, avoiding an additional casing string and a change of the design of the completion.

Causes and remedial measures for rockfall and landslides in Naini lake basin: Uttarakhand, India

The history of Naini Lake Basin reveals that this beautiful scenic natural surrounding has been a victim of landslides, mass erosion, rock-fall and slumping. Its location in highest rainfall zone, weak lithology and topography are the obvious reasons for these activities. Moreover the rising anthropogenic interferences like construction activities and deforestation on this geo-dynamically unstable zone has added more to the problem. The manuscript accounts of incidences of landslide and erosion activities, their causes and effects afterwards. An effort to stratify and to mark the comparatively lesser stable zones and patches in and around the lake basin has been made to demarcate the risk prone belt. Adequate measures for environmental planning and proper implementation of such plans are the utmost need of the hour to safeguard not only the beautiful basin but also the olives and property of population living under the continuous threat of disaster.

Validation and Analysis of Nonlinear System of Centrifugal Compressor using Hot Wire Flow Measurement and Jacobian Matrix

ABSTRACTA mathematical method is developed to predict surge and instability inception in a centrifugal compressor map based on Greitzer and Moore model. The method uses phase plane and Jacobian matrix to determine stable and unstable zone of centrifugal compressor and to extract limit cycle in unstable zone. In order to evaluate accuracy of analytical method, a compressor test rig facility is designed and tested in order to be compared with theoretical results. Accurate Honeywell piezoelectric pressure transducers are used to measure time averaged pressure at inlet and outlet ducts of the compressor. In order to record the flow fluctuation precisely, hot wire sensors are installed in entrance and exit of impeller. The results represent instability inception near true stall point but different from measured data. The discrepancy mostly originates from inlet and outlet ducts which causes measure stall point of compressor deviates from true one. An analytical method which is able to predict surge and instability in a compressor is highly significant for instrumentation and controlling of system.

Unsteady Flow Process in Mixed Waterjet Propulsion Pumps with Nozzle Based on Computational Fluid Dynamics

The unsteady flow process of waterjet pumps is related to the comprehensive performance and phenomenon of rotating stall and cavitation. To analyze the unsteady flow process on the unsteady condition, a computational domain containing nozzle, impeller, outlet guide vane (OGV), and shaft is established. The surface vortex of the blade is unstable at the valley point of the hydraulic unstable zone. The vortex core and morphological characteristics of the vortex will change in a small range with time. The flow of the best efficiency point and the start point of the hydraulic unstable zone on each turbo surface is relatively stable. At the valley point of the hydraulic unstable zone, the flow and pressure fields are unstable, which causes the flow on each turbo surface to change with time. The hydraulic performance parameters are measured by establishing the double cycle test loop of a waterjet propulsion device compared with numerical simulated data. The verification results show that the numerical simulation method is credible. In this paper, the outcome is helpful to comprehend the unsteady flow mechanism in the pump of waterjet propulsion devices, and improve and benefit their design and comprehensive performance.

Computational Analysis of a Compressor Rotor With Enhanced Airfoil

In this article, a compressor rotor blade is numerically modeled and solved by a CFD code. A stepped blade with higher aerodynamic characteristics is used to investigate unstable zone and improve operational limit and compressor stall. To validate numerical data original test case compared with experimental measurements. In this study, several locations of step on suction side of blades are tried, finally the results are compared with the case with no step on blades. It is shown that, by moving the step towards the leading edge, surge is delayed due to the reattachment of flow after the step. Efficiency is also decreased but lower than previous case.