Neural Generalized Predictive Control: A Newton-Raphson Implementation

An efficient implementation of Generalized Predictive Control using a multi-layer feedforward neural network as the plant's nonlinear model is presented. In using Newton-Raphson as the optimization algorithm, the number of iterations needed for convergence is significantly reduced from other techniques. The main cost of the Newton-Raphson algorithm is in the calculation of the Hessian, but even with this overhead the low iteration numbers make Newton-Raphson faster than other techniques and a viable algorithm for real-time control. This paper presents a detailed derivation of the Neural Generalized Predictive Control algorithm with Newton-Raphson as the minimization algorithm. Simulation results show convergence to a good solution within two iterations and timing data show that real-time control is possible. Comments about the algorithm's implementation are also included

Artificial intelligence and learning environments: Preface

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28724/1/0000545.pd

Control-Relevant Modeling, Analysis, and Design for Scramjet-Powered Hypersonic Vehicles

Within this paper, control-relevant vehicle design concepts are examined using a widely used 3 DOF (plus flexibility) nonlinear model for the longitudinal dynamics of a generic carrot-shaped scramjet powered hypersonic vehicle. Trade studies associated with vehicle/engine parameters are examined. The impact of parameters on control-relevant static properties (e.g. level-flight trimmable region, trim controls, AOA, thrust margin) and dynamic properties (e.g. instability and right half plane zero associated with flight path angle) are examined. Specific parameters considered include: inlet height, diffuser area ratio, lower forebody compression ramp inclination angle, engine location, center of gravity, and mass. Vehicle optimizations is also examined. Both static and dynamic considerations are addressed. The gap-metric optimized vehicle is obtained to illustrate how this control-centric concept can be used to "reduce" scheduling requirements for the final control system. A classic inner-outer loop control architecture and methodology is used to shed light on how specific vehicle/engine design parameter selections impact control system design. In short, the work represents an important first step toward revealing fundamental tradeoffs and systematically treating control-relevant vehicle design

Secondary Students' Dynamic Modeling Processes: Analyzing, Reasoning About, Synthesizing, and Testing Models of Stream Ecosystems

In this paper, we explore dynamic modeling as an opportunity for students to think about the science content they are learning. We examined the “Cognitive Strategies for Modeling” (CSMs) in which students engaged as they created dynamic models. We audio- and videotape-recorded eight pairs of ninth grade science students and analyzed their conversations and actions. In analyzing appropriate objects and factors for their model, some students merely enumerated potential factors whereas others engaged in rich, substantial, mindful analysis. In reasoning about their models, students discussed relationships in depth, concentrated only on the most important key relationships, or encountered difficulty distinguishing between causal and correlational relationships. In synthesizing working models, students mapped their model to aid visualization, focused on their goal, or talked about their model's appearance or form. Students attempted to articulate explanations for their relationships, but sometimes their explanations were shallow. In testing their models, some students tested thoroughly but only a few persisted in debugging their model's behavior so that it matched their expectations. In our conclusion we suggest that creating dynamic models has great potential for use in classrooms to engage students in thought about science content, particularly in those thinking strategies best fostered by dynamic modeling: analysis, relational reasoning, synthesis, testing and debugging, and making explanations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45184/1/10956_2004_Article_412477.pd

Standardized test outcomes for students engaged in inquiry-based science curricula in the context of urban reform

Considerable effort has been made over the past decade to address the needs of learners in large urban districts through scaleable reform initiatives. We examine the effects of a multifaceted scaling reform that focuses on supporting standards based science teaching in urban middle schools. The effort was one component of a systemic reform effort in the Detroit Public Schools, and was centered on highly specified and developed project-based inquiry science units supported by aligned professional development and learning technologies. Two cohorts of 7th and 8th graders that participated in the project units are compared with the remainder of the district population, using results from the high-stakes state standardized test in science. Both the initial and scaled up cohorts show increases in science content understanding and process skills over their peers, and significantly higher pass rates on the statewide test. The relative gains occur up to a year and a half after participation in the curriculum, and show little attenuation with in the second cohort when scaling occurred and the number of teachers involved increased. The effect of participation in units at different grade levels is independent and cumulative, with higher levels of participation associated with similarly higher achievement scores. Examination of results by gender reveals that the curriculum effort succeeds in reducing the gender gap in achievement experienced by urban African-American boys. These findings demonstrate that standards-based, inquiry science curriculum can lead to standardized achievement test gains in historically underserved urban students, when the curriculum is highly specified, developed, and aligned with professional development and administrative support. © 2008 Wiley Periodicals, Inc. J Res Sci Teach 45: 922–939, 2008Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/61206/1/20248_ftp.pd

Site-specific inductive and inhibitory activities of MMP-2 and MMP-3 orchestrate mammary gland branching morphogenesis

During puberty, mouse mammary epithelial ducts invade the stromal mammary fat pad in a wave of branching morphogenesis to form a complex ductal tree. Using pharmacologic and genetic approaches, we find that mammary gland branching morphogenesis requires transient matrix metalloproteinase (MMP) activity for invasion and branch point selection. MMP-2, but not MMP-9, facilitates terminal end bud invasion by inhibiting epithelial cell apoptosis at the start of puberty. Unexpectedly, MMP-2 also represses precocious lateral branching during mid-puberty. In contrast, MMP-3 induces secondary and tertiary lateral branching of ducts during mid-puberty and early pregnancy. Nevertheless, the mammary gland is able to develop lactational competence in MMP mutant mice. Thus, specific MMPs refine the mammary branching pattern by distinct mechanisms during mammary gland branching morphogenesis

BlackOPs: Increasing confidence in variant detection through mappability filtering

Identifying variants using high-throughput sequen-cing data is currently a challenge because true biological variants can be indistinguishable from technical artifacts. One source of technical arti-fact results from incorrectly aligning experimen-tally observed sequences to their true genomic origin (‘mismapping’) and inferring differences in mismapped sequences to be true variants. We de-veloped BlackOPs, an open-source tool that simu-lates experimental RNA-seq and DNA whole exome sequences derived from the reference genome, aligns these sequences by custom parameters, detects variants and outputs a blacklist of positions and alleles caused by mismapping. Blacklist

Tumor cell traffic through the extracellular matrix is controlled by the membrane-anchored collagenase MT1-MMP

As cancer cells traverse collagen-rich extracellular matrix (ECM) barriers and intravasate, they adopt a fibroblast-like phenotype and engage undefined proteolytic cascades that mediate invasive activity. Herein, we find that fibroblasts and cancer cells express an indistinguishable pericellular collagenolytic activity that allows them to traverse the ECM. Using fibroblasts isolated from gene-targeted mice, a matrix metalloproteinase (MMP)–dependent activity is identified that drives invasion independently of plasminogen, the gelatinase A/TIMP-2 axis, gelatinase B, collagenase-3, collagenase-2, or stromelysin-1. In contrast, deleting or suppressing expression of the membrane-tethered MMP, MT1-MMP, in fibroblasts or tumor cells results in a loss of collagenolytic and invasive activity in vitro or in vivo. Thus, MT1-MMP serves as the major cell-associated proteinase necessary to confer normal or neoplastic cells with invasive activity