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Modeling for the strap combined footings Part II: Mathematical model for design
Juan Antonio Yáñez-Palafox,Arnulfo Luévanos-Rojas,Sandra López-Chavarría,Manuel Medina-Elizondo 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.2
This paper presents the second part of the modeling for the strap combined footings, this part shows a mathematical model for design of strap combined footings subject to axial load and moments in two directions to each column considering the soil real pressure acting on the contact surface of the footing for one and/or two property lines of sides opposite restricted, the pressure is presented in terms of an axial load, moment around the axis “X” and moment around the axis “Y” to each column, and the methodology is developed using the principle that the derived of the moment is the shear force. The first part shows the optimal contact surface for the strap combined footings to obtain the most economical dimensioning on the soil (optimal area). The classic model considers an axial load and a moment around the axis “X” (transverse axis) applied to each column, i.e., the resultant force from the applied loads is located on the axis “Y” (longitudinal axis), and its position must match with the geometric center of the footing, and when the axial load and moments in two directions are presented, the maximum pressure and uniform applied throughout the contact surface of the footing is considered the same. A numerical example is presented to obtain the design of strap combined footings subject to an axial load and moments in two directions applied to each column. The mathematical approach suggested in this paper produces results that have a tangible accuracy for all problems and it can also be used for rectangular and T-shaped combined footings.
Development of a 60 Hz Power Standard Using SNS Programmable Josephson Voltage Standards
Burroughs, C.J.,Benz, S.P.,Dresselhaus, P.D.,Waltrip, B.C.,Nelson, T.L.,Yonuk Chong,Williams, J.M.,Henderson, D.,Patel, P.,Palafox, L.,Behr, R. Institute of Electrical and Electronics Engineers 2007 IEEE transactions on instrumentation and measureme Vol.56 No.2
<P>We are implementing a new standard for 60 Hz power measurements based on precision sinusoidal reference voltages from two independent programmable Josephson voltage standards (PJVS): one for voltage and one for current. The National Institute of Standards and Technology PJVS systems use series arrays of Josephson junctions to produce accurate quantum-based DC voltages. Using stepwise-approximation synthesis, the PJVS systems produce sinewaves with precisely calculable RMS voltage and spectral content. We present measurements and calculations that elucidate the sources of error in the RMS voltage that are intrinsic to the digital-synthesis technique and that are due to the finite rise times and transients that occur when switching between the discrete voltages. Our goal is to reduce all error sources and uncertainty contributions from the PJVS synthesized waveforms to a few parts in 10 <SUP>7</SUP> so that the overall uncertainty in the AC-power standard is a few parts in 10<SUP>6</SUP></P>
J. P. Morán-Lázaro,F. López-Urías,E. Muñoz-Sandoval,M. Courel-Piedrahita,A. Carreon-Alvarez,V. M. Rodríguez-Betancourtt,I. Zamudio-Torres,E. S. Guillén-López,A. Palafox-Corona 대한금속·재료학회 2023 ELECTRONIC MATERIALS LETTERS Vol.19 No.1
The acetone contained in human breath is of great interest for the health sector as it is a marker that allows to diagnoseand control diabetes in a non-invasive way. However, its concentration is extremely low. Therefore, high-performanceacetone sensors are still a challenge. With this in mind, MgCo 2 O 4 nanoparticles were synthesized using a microwaveassistedcolloidal route with subsequent calcination. Structural and morphological characterizations were done through varioustechniques. The MgCo 2 O 4 sensor was fabricated with the sample calcined at 500 °C. The sensing results showed that thesensor could detect acetone vapors ranging from 0.5 to 50 ppm at an optimum operating temperature of 250 °C with a highresponse, repeatability, stability, and selectivity. These sensing characteristics revealed that MgCo 2 O 4 could be used as a newsensor material to detect acetone in exhaled human breath.