Time filter

Source Type

East Los Angeles, United States

Gallegos H.A.,East Los Angeles College | Schubert J.E.,University of California at Irvine | Sanders B.F.,University of California at Irvine
Journal of Engineering Mechanics | Year: 2012

Dam safety and flood risk management programs are dependent on damage predictions that are difficult to validate and subject toconsiderable uncertainty. The 1963 Baldwin Hills dam-break flood caused high-velocity flows exceeding 5 m/s and structural failure of 41 wood-framed residences built in the mid-1940s, 16 of which were completely washed out. The flood is revisited here to examine the predictive skill and variability of established structural damage models when coupled with a hydraulic flood model that predicts parcel-scale depths and velocities. Two-way coupling is introduced so that predictions of structural failure affect localized flood predictions, which in turn affects damage predictions, in contrast to one-way coupling where structural failure has no impact on flood predictions. Two damage states defined by structural failure (Level 2) and washout (Level 3) are considered, along with 10 different structural damage models. One damage model considers flood depth alone, while the remaining nine consider a combination of depthand velocity defined by a constant discharge, energy, or force. Two-way coupling is shown to yield predictions with ~30% higher skill and 10% higher false alarms than one-way coupled models. Hence, there is a tradeoff between skill and false alarms that favors two-way coupling. Predictive skill is also shown to be sensitive to the structural damage classification and the damage model. Depth-based damage predictions yield low predictive skill as expected; however, across the nine velocity-based damage models, skill varies from 50 to 78% for structural failure and from 79 to 95% for washout. These results reveal a similar level of predictive uncertainty from the hydraulic model implementation, damage model, and damage classification. Results also point to flow force as a good predictor of both moderate (Level 2) and severe (Level 3) levels of damage. Through calibration, force thresholds of 0.75 and 9.5 m3/s2 arefound to maximize model skill at 85 and 95% for Level 2 and 3 damage, respectively, and these values compare well with previously published thresholds for similar building types. Finally, the results reveal a model bias toward a relatively wide damage zone compared with the observations; therefore, the high skill predictions are accompanied by a high rate of false alarms. © 2012 American Society of Civil Engineers. Source

Conrad S.,California State Polytechnic University, Pomona | Alvarez N.,East Los Angeles College
Journal of Web Librarianship | Year: 2016

User feedback on Web site design can be vital to understanding what issues library users may encounter when visiting a Web site, but obtaining this feedback can be time consuming, difficult to structure, and expensive. In past years, staff working on the Cal Poly Pomona University Library Web site collected user feedback from surveys and usability testing. This team was interested in acquiring a more basic understanding of how users interact with the Web in general, whether for research or other purposes, and how such experiences could inform design decisions. This article will discuss what focus groups are, why libraries should consider conducting focus groups for Web site testing and development, how focus groups can complement usability testing, and if focus groups are worth the time and effort. Results from focus group sessions will also be shared and discussed including information that fueled design decisions and benefits that participants gained from the experience. © 2016 Suzanna Conrad and Nathasha Alvarez Source

Schumpert B.,University of Washington | Schumpert B.,Valencia College | Garcia M.G.,University of Washington | Garcia M.G.,East Los Angeles College | And 3 more authors.
Mechanisms of Development | Year: 2013

Is focal adhesion kinase (FAK) needed for embryonic cleavage? We find that FAK is expressed during early cleavage divisions of sea urchin embryos as determined by polyclonal antibodies to the Lytechinus variegatus protein. FAK is absent in eggs and zygotes and then cycles in abundance during the first cleavages after fertilization. It is maximal at anaphase, similar to the destruction and synthesis of cyclin proteins. To investigate whether FAK is needed during early cleavage, we interfered with its function by microinjecting eggs with anti-FAK antibodies or with FAK antisense morpholino oligonucleotides. Both treatments led to regression of the cleavage furrow. FAK knockdown with antibodies or morpholino oligonucleotides also resulted in an over-accumulation of endocytic vesicles. Thus, FAK could be restricting endocytosis or increasing exocytosis in localized areas important for abscission. FAK appears to be necessary for successful cleavage. These results are the first to document a functional role for FAK during embryonic cleavage. © 2013 Elsevier Ireland Ltd. Source

Tall I.A.,East Los Angeles College
Automatica | Year: 2014

We address the problem of static state linearization of multi-input nonlinear control systems via coordinate transformation. Necessary and sufficient geometric conditions, in terms of certain set of vector fields associated with the system, were obtained in the early eighties stating the fact that such set of vector fields should be commutative and of constant rank. The state linearization problem, i.e., the finding of linearizing coordinates, was thus reduced to solving a set of partial differential equations. The objective of this paper is to provide an algorithm allowing to compute explicitly the linearizing state coordinates. The algorithm is performed using a maximum of n-1 steps (n being the dimension of the system) and is made possible by extending the explicit solvability of the Flow-Box Theorem to a commutative set of vector fields. Examples are provided to illustrate the results. An extension of the method to dynamic feedback linearization is also outlined. © 2014 Elsevier Ltd. All rights reserved. Source

Lopez J.J.,East Los Angeles College | Greer F.,Jet Propulsion Laboratory | Greer J.R.,California Institute of Technology
Journal of Applied Physics | Year: 2010

We report that single-layer graphene on a SiO2 /Si substrate withstands ion bombardment up to ∼7 times longer than expected when exposed to focused Ga+ ion beam. The exposure is performed in a dual beam scanning electron microscope/focused ion beam system at 30 kV accelerating voltage and 41 pA current. Ga+ ion flux is determined by sputtering a known volume of hydrogenated amorphous carbon film deposited via plasma-enhanced chemical vapor deposition. © 2010 American Institute of Physics. Source

Discover hidden collaborations