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Electrothermal Defect Detection in Powder Metallurgy Compacts

AIP Conference Proceedings 2006年第1期820卷 1201-1208页

作者： Souheil Benzerrouk Reinhold Ludwig Diran Apelian 1Powder Metallurgy Research Center Metal Processing Institute Worcester Polytechnic Institute Worcester MA 01609 2Department of Electrical and Computer Engineering Worcester Polytechnic Institute Worcester MA 01609

Faced with increasing market pressures, metal part manufacturers have turned to new processes and fabrication technologies. One of these processes is powder metallurgy (P/M), which is employed for low‐cost, high‐volume precision part manufacturing. Despite many advantages, the P/M process has created a number of challenges, including the need for high‐speed quality assessment and control, ideally for each compact. Consequently, sophisticated quality assurance is needed to rapidly detect flaws early in the manufacturing cycle and at minimal cost. In this paper we will discuss our progress made in designing and refining an active infrared (IR) detection system for P/M compacts. After discussing the theoretical background in terms of underlying equations and boundary conditions, analytical and numerical solutions are presented that are capable of predicting temperature responses for various defect sizes and orientations of a dynamic IR testing system. Preliminary measurements with controlled and industrial samples have shown that this active IR methodology can successfully be employed to test both green‐state and sintered P/M compacts. The developed system can overcome many limitations observed with a standard IR testing methodology such as emissivity, background calibration, and contact resistance.

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Mixed Semiconductor Alloys for Optical Devices

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Chemical and Biomolecular engineering 1000年第1期4卷 187-209页

作者： Thomas F. Kuech Luke J. Mawst April S. Brown 1Department of Chemical and Biological Engineering 2Department of Electrical and Computer Engineering University of Wisconsin–Madison Madison Wisconsin 53706 email: kuech@engr.wisc.edu mawst@engr.wisc.edu abrown@ee.duke.edu 3Department of Electrical and Computer Engineering Duke University Durham North Carolina 27708

There is an increasing technological need for a wider array of semiconducting materials that will allow greater control over the physical and electronic structure within multilayer heterostructures. This need has led to an expansion in the range of semiconducting alloys explored and used in new applications. These alloy semiconductors are often complicated by a limited range of miscibility. The current research has focused on the properties, stability, and detailed chemistry required to realize these materials. The use of synthetic conditions that permit the growth of these alloys to be dominated by kinetic rather than mass-transport considerations has allowed many of these nominally unstable materials to be grown and used in device structures. These materials have found important applications within optical communications as emitters and detectors and in solid-state lighting.

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Acoustic Backscatter Features Associated with Production of Tissue Homogenate using Pulsed Cavitational Ultrasound Therapy

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AIP Conference Proceedings 2006年第1期829卷 323-327页

作者： Jessica E. Parsons Charles A. Cain J. Brian Fowlkes 1Department of Biomedical Engineering University of Michigan Ann Arbor MI 48109 2Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109 3Department of Radiology University of Michigan Ann Arbor MI 48109

The use of a spatial variability criterion for acoustic backscatter is investigated as a potential method to assess lesion morphology and size in pulsed cavitational ultrasound therapy (PCUT). Backscatter signals were recorded during varied acoustic exposures that produced lesions in which tissue homogenate was either present or absent. Spatial variability was quantified by tracking changes in cross‐correlation sequences of A‐lines received during each exposure. Distributions of mean spatial variability are observed to be significantly higher for mechanically homogenized lesions than for those in which no homogenate is observed. A threshold spatial variability criterion is defined based on these distributions and is shown to be highly correlated (> 95%) with damage morphology. Furthermore, backscatter associated with the formation of homogenized lesions is characteristically observed to migrate away from the transducer during insonation. The magnitude of this backscatter shift is related to the axial dimension of the resultant lesion.

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Scene Representations for Robotic Spatial Perception

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Control, Robotics, and Autonomous Systems 1000年第1期8卷 351-377页

作者： Ruben Mascaro Margarita Chli 1Vision for Robotics Lab ETH Zurich Zurich Switzerland email: rmascaro@ethz.ch chlim@ethz.ch 2Department of Electrical and Computer Engineering University of Cyprus Nicosia Cyprus

The ability of a robot to build a persistent, accurate, and actionable model of its surroundings through sensor data in a timely manner is crucial for autonomous operation. While representing the world as a point cloud might be sufficient for localization, denser scene representations are required for obstacle avoidance. On the other hand, higher-level semantic information is often crucial for breaking down the necessary steps to autonomously complete a complex task, such as cooking. So the looming question is, What is a suitable scene representation for the robotic task at hand? This survey provides a comprehensive review of key approaches and frameworks driving progress in the field of robotic spatial perception, with a particular focus on the historical evolution and current trends in representation. By categorizing scene modeling techniques into three main types—metric, metric–semantic, and metric–semantic–topological—we discuss how spatial perception frameworks are transitioning from building purely geometric models of the world to more advanced data structures incorporating higher-level concepts, such as the notion of object instances and places. Special emphasis is placed on approaches for real-time simultaneous localization and mapping, their integration with deep learning for enhanced robustness and scene understanding, and their ability to handle scene dynamicity as some of the hottest topics of interest driving robotics research today. We conclude with a discussion of ongoing challenges and future research directions in the quest to develop robust and scalable spatial perception systems suitable for long-term autonomy.

关键词： spatial perception simultaneous localization and mapping SLAM semantic SLAM 3D scene graphs scene representations robotics

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Navigating the Complexity: The Sustainability Challenges in Global Value Chains

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Resource Economics 1000年第1期16卷 349-377页

作者： E. Berthet I. Fusacchia 1Department of Environmental and Resource Engineering and the Center for Absolute Sustainability Technical University of Denmark Kongens Lyngby Denmark email: etber@dtu.dk 2Department of Mathematics Computer Science and Economics University of Basilicata Potenza Italy

The global value chain (GVC) framework may provide a systematic approach to depict and advance sustainable path options at the global, national, and local scales. However, a coherent picture of the fragmented body of knowledge on the sustainability implications of GVCs is lacking. In an attempt to delineate the most effective perspective for addressing sustainability challenges within GVCs, this review explores the main academic streams that have emerged in response to the pressing need for detailed insights into GVCs. These academic streams include sociological, economic, and management approaches. We examine the intersections and distinctions among them, evaluating whether they converge or diverge in addressing sustainability within GVCs. By discussing the limitations and potential of these approaches, we suggest a possible integrated and appropriate research agenda to achieve an encompassing and still operative perspective to address current sustainability challenges.

关键词： global value chains literature review governance supply chain management sustainability JEL F6 JEL F18 JEL F23 JEL M14 JEL M21 JEL Q5

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Electromigration modeling for design rule development in microelectronic interconnects

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AIP Conference Proceedings 1999年第1期491卷 51-61页

作者： Robert J. Gleixner William K. Meyer William D. Nix 1Logic Technology Development Intel Corporation Hillsboro Oregon 97124-5503 2Department of Electrical and Computer Engineering Oregon Graduate Institute Portland Oregon 97291 3Department of Materials Science and Engineering Stanford University Stanford California 94305-2205

The use of a physically-based electromigration model as a means of validating design rules in aluminum-based microelectronic interconnects is presented. This model consider the migration of atoms through the line when driven by an applied current and mechanical stress gradients. The model is then applied to a specific interconnect geometry common to CMOS logic circuits. Here the saturation resistance in the interconnect is shown to agree well with experimental observations. The value of the effective charge (Z*) in this material is found to be −8.8. These results demonstrate the usefulness of electromigration modeling as a means of developing interconnect design rules.

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Identifying Regulatory Elements via Deep Learning

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Biomedical Data Science 1000年第1期3卷 315-338页

作者： Mira Barshai Eitamar Tripto Yaron Orenstein 1School of Electrical and Computer Engineering Ben-Gurion University of the Negev Beer-Sheva 8410501 Israel email: yaronore@bgu.ac.il 2Department of Biomedical Engineering Ben-Gurion University of the Negev Beer-Sheva 8410501 Israel

Deep neural networks have been revolutionizing the field of machine learning for the past several years. They have been applied with great success in many domains of the biomedical data sciences and are outperforming extant methods by a large margin. The ability of deep neural networks to pick up local image features and model the interactions between them makes them highly applicable to regulatory genomics. Instead of an image, the networks analyze DNA and RNA sequences and additional epigenomic data. In this review, we survey the successes of deep learning in the field of regulatory genomics. We first describe the fundamental building blocks of deep neural networks, popular architectures used in regulatory genomics, and their training process on molecular sequence data. We then review several key methods in different gene regulation domains. We start with the pioneering method DeepBind and its successors, which were developed to predict protein–DNA binding. We then review methods developed to predict and model epigenetic information, such as histone marks and nucleosome occupancy. Following epigenomics, we review methods to predict protein–RNA binding with its unique challenge of incorporating RNA structure information. Finally, we provide our overall view of the strengths and weaknesses of deep neural networks and prospects for future developments.

关键词： deep learning regulatory genomics gene regulation motif finding

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Privacy in Control and Dynamical Systems

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Control, Robotics, and Autonomous Systems 1000年第1期1卷 309-332页

作者： Shuo Han George J. Pappas 1Department of Electrical and Computer Engineering University of Illinois at Chicago Chicago Illinois 60607 USA email: hanshuo@uic.edu 2Department of Electrical and Systems Engineering University of Pennsylvania Philadelphia Pennsylvania 19104 USA email: pappasg@seas.upenn.edu

Many modern dynamical systems, such as smart grids and traffic networks, rely on user data for efficient operation. These data often contain sensitive information that the participating users do not wish to reveal to the public. One major challenge is to protect the privacy of participating users when utilizing user data. Over the past decade, differential privacy has emerged as a mathematically rigorous approach that provides strong privacy guarantees. In particular, differential privacy has several useful properties, including resistance to both postprocessing and the use of side information by adversaries. Although differential privacy was first proposed for static-database applications, this review focuses on its use in the context of control systems, in which the data under processing often take the form of data streams. Through two major applications—filtering and optimization algorithms—we illustrate the use of mathematical tools from control and optimization to convert a nonprivate algorithm to its private counterpart. These tools also enable us to quantify the trade-offs between privacy and system performance.

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Online Learning Algorithms

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Statistics and Its Application 1000年第1期8卷 165-190页

作者： Nicolò Cesa-Bianchi Francesco Orabona 1Department of Computer Science and Data Science Research Center Università degli Studi di Milano Milano 20133 Italy email: nicolo.cesa-bianchi@unimi.it 2Department of Electrical and Computer Engineering Boston University Boston Massachusetts 02215 USA email: francesco@***

Online learning is a framework for the design and analysis of algorithms that build predictive models by processing data one at the time. Besides being computationally efficient, online algorithms enjoy theoretical performance guarantees that do not rely on statistical assumptions on the data source. In this review, we describe some of the most important algorithmic ideas behind online learning and explain the main mathematical tools for their analysis. Our reference framework is online convex optimization, a sequential version of convex optimization within which most online algorithms are formulated. More specifically, we provide an in-depth description of online mirror descent and follow the regularized leader, two of the most fundamental algorithms in online learning. As the tuning of parameters is a typically difficult task in sequential data analysis, in the last part of the review we focus on coin-betting, an information-theoretic approach to the design of parameter-free online algorithms with good theoretical guarantees.

关键词： regret minimization convex optimization regression classification

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Pulse Laser Ignition of Preheated PETN

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AIP Conference Proceedings 2004年第1期706卷 1005-1008页

作者： K. Nagayama H. Ebisuzaki S. Kubota M. Nakahara 1Department of Aeronautics and Astronautics Faculty of Engineering Kyushu University Fukuoka 812‐8581 Japan 2Department of Earth Resources Engineering Faculty of Engineering Kyushu University Fukuoka 812‐8581 Japan 3Department of Computer and Communication Faculty of Engineering Fukuoka Institute of Technology Fukuoka811‐0295 Japan

Nd:YAG pulse laser was used to ignite powdered and preheated PETN. To enhance efficiency of laser absorption by PETN, it was mixed with a small amount of carbon black powder. In this study, we will propose two‐pulse laser ignition method, the first pulse is a long pulse to heat up PETN up to melting point, then second laser to ignite the heated PETN. By adopting this procedure, second short pulse laser energy can be reduced to ensure that the energy can be transferred by relatively slender plastic optical fiber. To simulate the slow laser heating process by long pulse laser, high‐power cw YAG laser up to 30W was used. While two ns‐YAG laser of about 200 mJ/pulse with 4 ns and 12 ns were used for ignition. Higher peak power with donut‐like profile laser beam of 4 ns duration gives damage to fibers, while lower peak power with relatively flat profile laser beam of 12 ns duration can safely pass through optical fiber of 1 mm diameter. We performed a series of melting experiments of PETN under normal optical microscope. From these experiments, the experimental conditions and time to the onset of PETN melting was determined. Then the ignition experiments were performed by choosing a delay time between two laser irradiation timing as a parameter. Shortest detonation delay was evidenced at the delay time close to the time that the PETN specimen is almost starting to melt.

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