33,308 research outputs found
Identification of Critical Water Levels in Flooded Rice Fields
A mathematical model was developed to simulate the transient hydrology of a flooded rice field. With the model, users can determine the critical interlevee areas in which to monitor the water levels so that the irrigation well can be turned on at the critical low water level, and turned off at the critical high water level, in order to maximize water application efficiency. Sensitivity analysis performed with the model showed that it will be necessary to calibrate the model for each specific field. A calibration procedure has been developed
High temperature solder device for flat cables
A high temperature solder device for flat cables includes a microwelder, an anvil which acts as a heat sink and supports a flexible flat ribbon cable that is to be connected to a multiple pin connector. The microwelder is made from a modified commercially available resistance welding machine such as the Split Tip Electrode microwelder by Weltek, which consists of two separate electrode halves with a removable dielectric spacer in between. The microwelder is not used to weld the items together, but to provide a controlled compressive force on, and energy pulse to, a solder preform placed between a pin of the connector and a conductor of the flexible flat ribbon cable. When the microwelder is operated, an electric pulse will flow down one electrode, through the solder preform and back up the other electrode. This pulse of electrical energy will cause the solder preform to heat up and melt, joining the pin and conductor
Dynamical Formation of the GW150914 Binary Black Hole
We explore the possibility that GW150914, the binary black hole merger
recently detected by Advanced LIGO, was formed by gravitational interactions in
the core of a dense star cluster. Using models of globular clusters with
detailed -body dynamics and stellar evolution, we show that a typical
cluster with a mass of to is
optimal for forming GW150914-like binary black holes that will merge in the
local universe. We identify the most likely dynamical processes for forming
GW150914 in such a cluster, and we show that the detection of GW150914 is
consistent with the masses and merger rates expected for binary black hole
mergers from globular clusters. Our results show that dynamical processes
provide a significant and well-understood pathway for forming binary black hole
mergers in the local universe. Understanding the contribution of dynamics to
the binary black hole merger problem is a critical step in unlocking the full
potential of gravitational-wave astronomy.Comment: Accepted by ApJ Letter
Overview of rocket engine control
The issues of Chemical Rocket Engine Control are broadly covered. The basic feedback information and control variables used in expendable and reusable rocket engines, such as Space Shuttle Main Engine, are discussed. The deficiencies of current approaches are considered and a brief introduction to Intelligent Control Systems for rocket engines (and vehicles) is presented
Image gathering, coding, and processing: End-to-end optimization for efficient and robust acquisition of visual information
Researchers are concerned with the end-to-end performance of image gathering, coding, and processing. The applications range from high-resolution television to vision-based robotics, wherever the resolution, efficiency and robustness of visual information acquisition and processing are critical. For the presentation at this workshop, it is convenient to divide research activities into the following two overlapping areas: The first is the development of focal-plane processing techniques and technology to effectively combine image gathering with coding, with an emphasis on low-level vision processing akin to the retinal processing in human vision. The approach includes the familiar Laplacian pyramid, the new intensity-dependent spatial summation, and parallel sensing/processing networks. Three-dimensional image gathering is attained by combining laser ranging with sensor-array imaging. The second is the rigorous extension of information theory and optimal filtering to visual information acquisition and processing. The goal is to provide a comprehensive methodology for quantitatively assessing the end-to-end performance of image gathering, coding, and processing
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