Vibration Response Models of a Stiffened Aluminum Plate Excited by a Shaker

Numerical models of structural-acoustic interactions are of interest to aircraft designers and the space program. This paper describes a comparison between two energy finite element codes, a statistical energy analysis code, a structural finite element code, and the experimentally measured response of a stiffened aluminum plate excited by a shaker. Different methods for modeling the stiffeners and the power input from the shaker are discussed. The results show that the energy codes (energy finite element and statistical energy analysis) accurately predicted the measured mean square velocity of the plate. In addition, predictions from an energy finite element code had the best spatial correlation with measured velocities. However, predictions from a considerably simpler, single subsystem, statistical energy analysis model also correlated well with the spatial velocity distribution. The results highlight a need for further work to understand the relationship between modeling assumptions and the prediction results

Evaluating School District 428\u27s Curriculum Media Development Center\u27s Clientele

The Curriculum Media Development Center was conceptualized by the Illinois Office of Education and Vocational Services and the Illinois Depaartment of Corrections to meet the need for specially developed instructional materials in reading and math for Title I students being served by School District 428. The project began in 1974 and was located at the Illinois Youth Center, St. Charles. However, during 1979, it became apparent that because of its location in Kane County, the Curriculum Media Development Center was providing services primarily to those institutions in the northeast quadrant of Illinois. In January of 1980 the decision was made to relocate this project to the Department of Corrections headquarters in Springfield, Illinois in an effort to make it more accessible to all institutions within the state. This study represents an attempt by this researcher to determine if the Curriculum Media Development Center is in fact more responsive to the requests for materials from all institutions, both adult and juvenile, since its relocation to Springfield; and from which group of educators, Title I or Core Curriculum, those requests originated. Data for this study was gathered from an analysis of the production request forms for Fiscal Year 1980 and Fiscal Year 1982, the years immediately preceding and following the year in which the Curriculum Media Development Center was moved to Springfield. In Fiscal Year 1980, forty-three percent of all requests originated in the Juvenile Division. In Fiscal Year 1982 only twenty-two percent of all requests originated in the Juvenile Division, and seventy-eight percent from the Adult Division. Coincidentally, this is the same percentage of students served by School District 428 in each division. The data does indicate that relocating the Curriculum Media Development Center to Springfield generated more requests from those institutions located in the southern portion of the state (six adult, two juvenile). However, the data does not support the contention that the juvenile division has suffered because of the move but rather that the adult division has simply submitted more requests during the period of this study

CREATIVE STRATEGIES FOR DEALING WITH DISINFORMATION

On November 13, 2023, Randolph H. Pherson presented on Creative Strategies for Dealing with Disinformation for this year’s West Coast Security Conference. The key points discussed were the analytical vulnerabilities that cause readers to fall victim to disinformation, strategies for countering disinformation, and the importance of reframing public perceptions of intelligence analysis.   Received: 01-10-2024 Revised: 01-30-202

Enrichment Procedures for Soft Clusters: A Statistical Test and its Applications

Clusters, typically mined by modeling locality of attribute spaces, are often evaluated for their ability to demonstrate ‘enrichment’ of categorical features. A cluster enrichment procedure evaluates the membership of a cluster for significant representation in pre-defined categories of interest. While classical enrichment procedures assume a hard clustering definition, in this paper we introduce a new statistical test that computes enrichments for soft clusters. We demonstrate an application of this test in refining and evaluating soft clusters for classification of remotely sensed images

An SMP Soft Classification Algorithm for Remote Sensing

This work introduces a symmetric multiprocessing (SMP) version of the continuous iterative guided spectral class rejection (CIGSCR) algorithm, a semiautomated classification algorithm for remote sensing (multispectral) images. The algorithm uses soft data clusters to produce a soft classification containing inherently more information than a comparable hard classification at an increased computational cost. Previous work suggests that similar algorithms achieve good parallel scalability, motivating the parallel algorithm development work here. Experimental results of applying parallel CIGSCR to an image with approximately 10^8 pixels and six bands demonstrate superlinear speedup. A soft two class classification is generated in just over four minutes using 32 processors

Dual-Use Transducer for Use with a Boundary-Stiffened Panel and Method of Using the Same

A transducer for use with a boundary-stiffened panel has an inter-digitated electrode (IDE) and a piezoelectric wafer portion positioned therebetween. The IDE and/or the wafer portion are triangular, with one edge or side aligned with a boundary edge of the panel. The transducer generates and transmits an output force to the panel in response to an input voltage signal from a sensor, which can be another transducer as described above or an accelerometer. A controller can generate an output force signal in response to the input voltage signal to help cancel the input voltage signal. A method of using the transducer minimizes vibration in the panel by connecting multiple transducers around a perimeter thereof. Motion is measured at different portions of the panel, and a voltage signal determined from the motion is transmitted to the transducers to generate an output force at least partially cancelling or damping the motion