Seismic Performance of Concrete-Filled FRP Tube Columns for Bridge Substructure

A set of column-footing subassemblies were prepared to investigate construction feasibility and seismic performance of structural joints for concrete-filled fiber reinforced polymer (FRP) tubes (CFFT) as bridge substructure. Based on the common practices of the precast industry and previous research on CFFT, the test matrix included a control reinforced concrete (RC) column and three CFFT columns, all with similar RC footings. The three CFFT columns included a cast-in-place CFFT column with starter bars, a precast CFFT column with grouted starter bars, and a precast CFFT column with unbonded posttensioned rods. The columns were subjected to a constant axial load and a pseudostatic lateral load. All proposed joints proved feasible in construction and robust under extreme load conditions. FRP tube, when secured properly in the footing, showed great influence on the seismic performance of the column by providing both longitudinal reinforcement and hoop confinement to the core concrete. The CFFT columns exhibited significant improvement over traditional RC columns in both ultimate strength and ductility. The study also showed that practices of the precast concrete industry can be easily and effectively implemented for the CFFT column construction.     

Structural Fault Modeling and Fault Detection Through Neyman–Pearson Decision Criteria for Analog Integrated Circuits

A new approach for analog fault modeling and simulation is presented. The proposed approach utilizes the sensitivity of the circuit’s DC node voltages to the process variations and consequently the current deviance so as to differentiate the faulty behavior. A systematic method is proposed for the fault discrimination to minimize the probability that the circuit is accepted as a fault-free when it is faulty. Tests are generated and evaluated taking into account the potential fault masking effects of process spread on the faulty circuit responses. The introduced fault model is validated on a time-interleaved sample-and-hold circuit. Simulation results demonstrate the effectiveness of the model.     

Monitoring Interfaces for Faults

We consider the problem of a module interacting with an external interface (environment) where the interaction is expected to satisfy some system specification Φ. While we have the full implementation details of the module, we are only given a partial external specification for the interface. The interface specification being partial (incomplete) means that the interface displays only a strict subset of the behaviors allowed by the interface specification.Based on the assumption that interface specifications are typically incomplete, we address the question of whether we can tighten the interface specification into a strategy, consistent with the given partial specification, that will guarantee that all possible interactions resulting from possible behaviors of the module will satisfy the system specification Φ. We refer to such a tighter specification as Φ-guaranteeing specification. Rather than verifying whether the interface, which is often an off-the-shelf component, satisfies the tighter specification, the paper proposes a construction of a run-time monitor which continuously checks the existence of a Φ-guaranteeing interface.We view the module and the external interface as players in a 2-player game. The interface has a winning strategy if it can guarantee that no matter what the module does, the overall specification Φ is met. The problem of incomplete specifications is resolved by allowing the interface to follow any strategy consistent with the interface specification. Our approach essentially combines traditional run-time monitoring and static analysis. This allows going beyond the focus of traditional run-time monitoring tools – error detection in the execution trace, towards the focus of the static analysis – bug detection in the programs.     

Transient detection in COTS processors using software approach

This paper presents a software-based error detection scheme called enhanced committed instructions counting (ECIC) for embedded and real-time systems using commercial off-the-shelf (COTS) processors. The scheme uses the internal performance monitoring features of a processor, which provides the ability to count the number of committed instructions in a program. To evaluate the ECIC scheme, 6000 software induced faults are injected into a 32-bit Pentium® processor. The results show that the error detection coverage varies between 90.52% and 98.18%, for different workloads.     

In vivo quantitative three-dimensional localization of tumor labeled with exogenous specific fluorescence markers

We introduce a diffused optical detection system based on the administration of a fluorophore-antibody conjugate to diseased tissue. The conjugate interacts with the antigens expressed by the diseased tissue, resulting in fluorescent labeling of the antigen. By combining an optical detection system with a reconstruction algorithm developed on the basis of the random-walk model, we were able to determine the position of the fluorophore (and, thus, of the diseased cells) in the tissue. We present three-dimensional reconstructions of the location of a fluorophore (FITC-fluorescein isothiocyanate) in the tongues of mice. Measurements were performed with the fluorophore embedded at various simulated depths. The simulations were performed with agarose-based gel slabs applied to the tongue as tissuelike phantoms. Reconstructed fluorophore locations agree well with the actual values.     

Sensitivity analysis of narrowband photonic crystal filters and waveguides to structure variations and inaccuracy

Photonic crystal microcavities, formed by local defects within an otherwise perfectly periodic structure, can be used as narrowband optical resonators and filters. The coupled-cavity waveguide (CCW) is a linear array of equally spaced identical microcavities. Tunneling of light between microcavities forms a guiding effect, with a central frequency and bandwidth controlled by the local defects' parameters and spacing, respectively. We employ cavity perturbation theory to investigate the sensitivity of microcavities and CCWs to random structure inaccuracies. For the microcavity, we predict a frequency shift that is due to random changes in the lattice structure and show an approximate linear dependence between the standard deviation of the structure inaccuracy and that of the resonant frequency. The effect of structural inaccuracy on the CCW devices, however, is different; it has practically no effect on the CCW performance if it is below a certain threshold but may destroy the CCW if this threshold is exceeded.     

The hardness of the Expected Decision Depth problem

Given a function f over n binary variables, and an ordering of the n variables, we consider the Expected Decision Depth problem. Namely, what is the expected number of bits that need to be observed until the value of the function is determined, when bits of the input are observed according to the given order. Our main finding is that this problem is (essentially) #P-complete. Moreover, the hardness holds even when the function f is represented as a decision tree.     

Georeferenced Registration of Construction Graphics in Mobile Outdoor Augmented Reality

This paper describes research that investigated the application of the global positioning system and 3 degree-of-freedom (3-DOF) angular tracking to address the registration problem during interactive visualization of construction graphics in outdoor augmented reality (AR) environments. The global position and the three-dimensional (3D) orientation of a user’s viewpoint are tracked, and this information is reconciled with the known global position and orientation of superimposed computer-aided design (CAD) objects. Based on this computation, the relative translation and axial rotations between the user’s viewpoint and the CAD objects are continually calculated. The relative geometric transformations are then applied to the CAD objects inside a virtual viewing frustum that is coincided with the real world space that is in the user’s view. The result is an augmented outdoor environment where superimposed graphical objects stay fixed to their real world locations as the user navigates. The algorithms are implemented in a software tool called UM-AR-GPS-ROVER that is capable of interactively placing static and dynamic 3D models at any location in outdoor augmented space. The concept and prototype are demonstrated with an example in which scheduled construction activities for the erection of a structural steel frame are graphically simulated in outdoor AR.     

Hydrothermally Oxidized Single‐Walled Carbon Nanotube Networks for High Volumetric Electrochemical Energy Storage

Improving volumetric energy density is one of the major challenges in nanostructured carbon electrodes for electrochemical energy storage device applications. Herein, a simple hydrothermal oxidation process of single‐walled carbon nanotube (SWNT) networks in dilute nitric acid is reported, enabling simultaneous physical densification and chemical functionalization of the as‐assembled randomly‐packed SWNT films. After the hydrothermal oxidation process, the density of the SWNT films increases from 0.63 to 1.02 g cm^?3 and a considerable amount of redox‐active oxygen functional groups are introduced on the surface of the SWNTs. The functionalized SWNT films are used as positive electrodes against Li metal negative electrodes for potential Li‐ion capacitors or Li‐ion battery applications. The functionalized SWNT electrodes deliver high volumetric as well as gravimetric capacities, 154 Ah L^?1 and 152 mAh g^?1, respectively, owing to the surface redox reactions between the introduced oxygen functional groups and Li ions. In addition, these electrodes exhibit a remarkable rate‐capability by retaining its high capacity of 94 Ah L^?1 (92 mAh g^?1) at a high discharge rate of 10 A g^?1. These results demonstrate the simple hydrothermal oxidation process as an attractive strategy for improving the volumetric performance of nanostructured carbon electrodes.