Comparison of NASTRAN analysis with ground vibration results of UH-60A NASA/AEFA test configuration

Preceding program flight tests, a ground vibration test and modal test analysis of a UH-60A Black Hawk helicopter was conducted by Sikorsky Aircraft to complement the UH-60A test plan and NASA/ARMY Modern Technology Rotor Airloads Program. The 'NASA/AEFA' shake test configuration was tested for modal frequencies and shapes and compared with its NASTRAN finite element model counterpart to give correlative results. Based upon previous findings, significant differences in modal data existed and were attributed to assumptions regarding the influence of secondary structure contributions in the preliminary NASTRAN modeling. An analysis of an updated finite element model including several secondary structural additions has confirmed that the inclusion of specific secondary components produces a significant effect on modal frequency and free-response shapes and improves correlations at lower frequencies with shake test data

NASTRAN Modeling of Flight Test Components for UH-60A Airloads Program Test Configuration

Based upon the recommendations of the UH-60A Airloads Program Review Committee, work towards a NASTRAN remodeling effort has been conducted. This effort modeled and added the necessary structural/mass components to the existing UH-60A baseline NASTRAN model to reflect the addition of flight test components currently in place on the UH-60A Airloads Program Test Configuration used in NASA-Ames Research Center's Modern Technology Rotor Airloads Program. These components include necessary flight hardware such as instrument booms, movable ballast cart, equipment mounting racks, etc. Recent modeling revisions have also been included in the analyses to reflect the inclusion of new and updated primary and secondary structural components (i.e., tail rotor shaft service cover, tail rotor pylon) and improvements to the existing finite element mesh (i.e., revisions of material property estimates). Mode frequency and shape results have shown that components such as the Trimmable Ballast System baseplate and its respective payload ballast have caused a significant frequency change in a limited number of modes while only small percent changes in mode frequency are brought about with the addition of the other MTRAP flight components. With the addition of the MTRAP flight components, update of the primary and secondary structural model, and imposition of the final MTRAP weight distribution, modal results are computed representative of the 'best' model presently available

A Response to Submitting to the Disciplines of Liberation

When Bill Koch quoted Mark Van Doren at the beginning of his article, he situated me within a familiar context as a teacher and a lifelong learner: “There is no more perfect situation…than teachers teaching teachers.” My first thoughts in relation to this were of my time as part of the Illinois State Writing Project, a site within the National Writing Project, located in Normal, Illinois. “Teachers teaching teachers” provides the foundation within which the National Writing Project operates, and it is a motto that has been ingrained in me as both a teacher and a mentor of other teachers. With his reference to an already-familiar concept, Dr. Koch drew me into his conversation about teaching, inviting me to listen and giving me permission to join. It is this sense of familiarity and belonging which becomes integral to our teaching that I wish to discuss in regards to Koch’s comments upon education in his reflection on Van Doren’s Liberal Education. In particular, I wish to discuss how it applies to students in the developmental writing classroom

Experimental Performance of Concrete Columns with Composite Jackets under Blast Loading

Measures to prevent progressive collapse of structures include protection of critical elements such as columns. In support of this goal, nine tests were conducted to assess the as-built performance of typical columns and the effectiveness of carbon fiber jackets in improving their performance. A quasi-static load protocol was developed to replicate in the laboratory the damage patterns observed in blast testing in the field. Load-deflection curves (resistance functions) and jacket strain were measured. Jackets were observed to change the failure mode from brittle shear to ductile flexure and to increase the load and displacement capacities of the column. Variations in jacket strain are discussed and experimental results are used to assess predictive models for shear capacity and resistance functions. The data support the use of these models for design but identify some limitations in the resistance functions.Keywords: Fiber Reinforced Plastics, Blast Loads, Full-Scale Tests, Concrete Columns, Rehabilitatio

A Consensus Definitive Classification of Scavenger Receptors and Their Roles in Health and Disease

Scavenger receptors constitute a large family of proteins that are structurally diverse and participate in a wide range of biological functions. These receptors are expressed predominantly by myeloid cells and recognize a diverse variety of ligands including endogenous and modified host-derived molecules and microbial pathogens. There are currently eight classes of scavenger receptors, many of which have multiple names, leading to inconsistencies and confusion in the literature. To address this problem, a workshop was organized by theUnited StatesNational Institute of Allergy and Infectious Diseases, National Institutes of Health, to help develop a clear definition of scavenger receptors and a standardized nomenclature based on that definition. Fifteen experts in the scavenger receptor field attended the workshop and, after extensive discussion, reached a consensus regarding the definition of scavenger receptors and a proposed scavenger receptor nomenclature. Scavenger receptors were defined as cell surface receptors that typically bind multiple ligands and promote the removal of nonself or altered-self targets. They often function by mechanisms that include endocytosis, phagocytosis, adhesion, and signaling that ultimately lead to the elimination of degraded or harmful substances. Based on this definition, nomenclature and classification of these receptors into 10 classes were proposed. This classification was discussed at three national meetings and input from participants at these meetings was requested. The following manuscript is a consensus statement that combines the recommendations of the initial workshop and incorporates the input received from the participants at the three national meetings

Seismic retrofit schemes for RC structures and local-global consequences

A review of repair schemes for reinforced concrete frame buildings is presented in this paper, within the context of global objectives of the intervention process. Local as well as global intervention measures are discussed and their technological application details outlined. The effect of the reviewed repair schemes on the member, sub‐assemblage and system performance are qualitatively assessed. The important role of the foundation system in the rehabilitation process is outlined and measures that are consistent with the super‐structure intervention methods are given. The paper concludes with a global assessment of the effect of repair methods on stiffness, strength and ductility, the three most important seismic response parameters, to assist researchers and practitioners in decision‐making to satisfy their respective intervention objectives. The framework for the paper complies with the requirements of consequence‐based Engineering, where the expected damage is addressed only when consequences are higher than acceptable consequences, and a cyclical process of assessment and re‐assessment is undertaken until the community objectives are deemed to be satisfied

Preassembled shear units for flat slabs

Bibliography: p. 176-178