Hydropower impact on the river flow of a humid regional climate

Land use and water management have considerable impacts on regional climates. This paper proposes that in humid regions with low wind patterns the construction of hydropower storage reservoirs contributes to the increases in the probability of precipitation in the regional climate. This observation has been tested with a methodology that calculates the cumulative influence of reservoir construction in the basins surrounding with a proposed index named Cumulative Impact of Existing Reservoirs, and compares this index with the historical flow of the rivers. It was found that the construction of reservoirs in Brazil had a considerable impact on its river flows

Challenges and opportunities for a South America Waterway System

South America has been developed from its coast to its hinterlands since the beginning of its Western colonization. However, to this point, no significant effort has been made to integrate its interior. Waterways transportation can be considered the most sustainable inland mode of transportation due to its low CO2 emissions per ton of cargo transport. With this in mind, this paper investigates the history, challenges and opportunities of the past proposals for the construction of the South America Waterway System (SAWS) connecting the La Plata, Amazon, and Orinoco river basins. It focuses on particular challenges of the proposed waterway. (i) a comparison between the deforestation surrounding existing road and waterway infrastructure in the Amazon, (ii) the large water level variation in the Amazon basin, (iii) and the alternatives for storing water to reduce the impacts of floods and droughts in the proposed waterway. We conclude that deforestation surrounding existing waterways is practically zero and that groundwater storage has an important role in storing water for the basin and reservoirs, a limited one. The SAWS can significantly foster South American integration, encourage sustainable extraction of natural resources in the region and help the conservation of the Amazon forest

Cooling down the world oceans and the earth by enhancing the North Atlantic Ocean current

The world is going through intensive changes due to global warming. It is well known that the reduction in ice cover in the Arctic Ocean further contributes to increasing the atmospheric Arctic temperature due to the reduction of the albedo effect and increase in heat absorbed by the ocean’s surface. The Arctic ice cover also works like an insulation sheet, keeping the heat in the ocean from dissipating into the cold Arctic atmosphere. Increasing the salinity of the Arctic Ocean surface would allow the warmer and less salty North Atlantic Ocean current to flow on the surface of the Arctic Ocean considerably increasing the temperature of the Arctic atmosphere and release the ocean heat trapped under the ice. This paper argues that if the North Atlantic Ocean current could maintain the Arctic Ocean ice-free during the winter, the longwave radiation heat loss into space would be larger than the increase in heat absorption due to the albedo effect. This paper presents details of the fundamentals of the Arctic Ocean circulation and presents three possible approaches for increasing the salinity of the surface water of the Arctic Ocean. It then discusses that increasing the salinity of the Arctic Ocean would warm the atmosphere of the Arctic region, but cool down the oceans and possibly the Earth. However, it might take thousands of years for the effects of cooling the oceans to cool the global average atmospheric temperature

Identification Of Mixed Operational Modes In Rotating Machinery Using The Tvdft Order Tracking Technique

In this paper, the TVDFT Order Tracking technique (Time Variant Discrete Fourier Transform) is used to process complex non-stationary signals, generated by real measured signals. The method is applied in an experimental set-up for several run-ups, in order to identify the forward and backward precession movement in the directional order map. In this map, the negative orders are related to the backward and the positive ones to the forward orbit movement. The directional order maps are obtained for several rotor stations in order to identify the mixed operational modes, i.e., when some stations of the rotor describe their precessional movement in the forward direction while others move in the backward direction simultaneously. The experimental results showed the influence of the spatial distribution of the imbalance in the occurrence of the mixed operational modes. Copyright © 2004 Society of Automotive Engineers, Inc.Southwick, D., Using Full Spectrum Plots (1993) ORBIT, 14. , December, Bently Nevada CorporationHan, Y.S., Lee, C.W., Directional Wigner Distribution for Order Analysis in Rotating/Reciprocating Machines (1999) Mechanical System and Signal Processing, 13 (5), pp. 723-737Blough, J.R., Brown, D.L., Vold, H., Order Tracking with Time Variant Discrete Fourier Transform (1996) Proceedings of the 21st International Seminar of Modal Analysis - Noise and Vibration Engineering, pp. 1515-1525. , Leuven, BelgiumBlough, J.R., (1998) Improving the Analysis of Operating Data on Rotating Automotive Components, , Department of Mechanical, Industrial, and Nuclear Engineering of the College of Engineering, University of Cincinnati, CincinnatiPotter, R., A New Order Tracking Method for Rotating Machinery (1990) Sound and Vibration Magazine, 24 (9), pp. 30-34Vold, H., Leuridan, J., High Resolution Order Tracking at Extreme Slew Rates, Using Kalman Tracking Filters (1993) Proceedings of the Noise and Vibration Conference, SAE Technical Paper 931288, , Tranverse City, MI, USAVold, H., Mains, M., Blough, J.R., Theoretical Foundations for High Performance Order Tracking with the Vold-Kalman Filter (1997) Proceedings of the Noise and Vibration Conference, SAE Technical Paper 972007, , Traverse City, MI, USADias, Jr.M., Allemang, R.J., Some Insights into the Simultaneous Forward and Backward Whirling of Rotors (2000) Proceedings of the 20th IMACDias, Jr.M., Idehara, S.J., Mesquita, A.L.A., Miranda, U.A., On the Simultaneous Forward and Backward Whirling of Flexible Rotors: Numerical Analysis and Experimental Verification (2002) 6th International Conference on Rotor Dynamics, pp. 496-503. , IFToMM, Sydney, Australi

Instantaneous Rotational Speed Identification Using The Directional Wigner Distribution And Its Application To Order Analysis

The quality of the results of any order analysis depends on the accuracy of the tachometer signal used to estimate the instantaneous rotational speed. There are several techniques used to process the tachometer signal. However, in some cases, there are difficulties in measuring this signal due to physical limitations of the equipment under analysis. This paper investigates a methodology to estimate the instantaneous frequency of a nonstationary signal using the Directional Wigner Distribution. Therefore, the variation of the rotational speed of a rotating equipment can be obtained using only the accelerometer signal, eliminating the need of acquiring the tachometer signal. Copyright © 2003 Society of Automotive Engineers, Inc.Lee, C.W., Han, Y.-S., The directional Wigner distribution and its applications (1998) Journal of Sound and Vibration, 216 (4), pp. 585-600Han, Y.S., Lee, C.W., Directional Wigner Distribution for Order Analysis in Rotating/Reciprocating Machines (1999) Mechanical System and Signal Processing, 13 (5), pp. 723-737Fyfe, K., Munck, D., Analysis of Computed Order Tracking (1997) Mechanical System and Signal Processing, 11 (2), pp. 187-205Potter, R., Gribler, M., Computed Order Tracking Obsoletes Older Methods (1989) Proc. of the SAE, pp. 63-67. , http://www.sae.org/technical/papers/891131, SAE paper 891131Potter, R., A New Order Tracking Method for Rotating Machinery (1990) Sound and Vibration Magazine, 24 (9), pp. 30-34Packard, H., Appendice A - Computed Synchronous Resampling and Order Tracking Effective Measurements Using Dynamic Signal Analyzers, Application Note, 243 (1), pp. 64-69Vold, H., Leuridan, J., High Resolution Order Tracking at Extreme Slew Rates Using Kalman Tracking Filters (1993) Proc. of the SAE, Noise and Vibration Conference, pp. 219-226. , http://www.sae.org/technical/papers/931288, SAE Paper 931288Vold, H., Herlufsen, H., Mains, M., Corwin-Renner, D., Multi axle order tracking with the Vold-Kalman tracking filter (1997) S V Sound and Vibration, 31 (5), pp. 30-34Blough, J., Brown, D., Vold, H., Order Tracking with the Time Variant Discrete Fourier Transform (1996) Proc. Int. Sem. of Modal Analysis, pp. 1515-1525. , BelgiumBlough, J., (1998) Improving the Analysis of Operating Data on Rotating Automotive Components, , Ph.D. Dissertation, University of CincinnatiLembregts, F., Top J, J., Neyrinck, F., Adaptive Resampling for Off-Line Signal Processing (1996) ISMA21Crochiere, R., Rabiner, L., (1983) Multirate Digital Signal Processing, , Prentice Hall, New JerseyCohen, L., (1995) Time-Frequency Analysis, , Prentice Hall, New Yor