Testing of Depth-Encoded Hough Voting for Infrastructure Object Detection

The lack of viable methods to map and label existing infrastructure is one of the engineering grand challenges for the 21st century. For instance, over two thirds of the effort needed to geometrically model even simple infrastructure is spent on manually converting a cloud of points to a 3D model. The result is that few facilities today have a complete record of as-built information and that as-built models are not produced for the vast majority of new construction and retrofit projects. This leads to rework and design changes that can cost up to 10% of the installed costs. Automatically detecting building components could address this challenge. However, existing methods for detecting building components are not view and scale-invariant, or have only been validated in restricted scenarios that require a priori knowledge without considering occlusions. This leads to their constrained applicability in complex civil infrastructure scenes. In this paper, we test a pose-invariant method of labeling existing infrastructure. This method simultaneously detects objects and estimates their poses. It takes advantage of a recent novel formulation for object detection and customizes it to generic civil infrastructure scenes. Our preliminary experiments demonstrate that this method achieves convincing recognition results.

Internal representations of temporal statistics and feedback calibrate motor-sensory interval timing.

Humans have been shown to adapt to the temporal statistics of timing tasks so as to optimize the accuracy of their responses, in agreement with the predictions of Bayesian integration. This suggests that they build an internal representation of both the experimentally imposed distribution of time intervals (the prior) and of the error (the loss function). The responses of a Bayesian ideal observer depend crucially on these internal representations, which have only been previously studied for simple distributions. To study the nature of these representations we asked subjects to reproduce time intervals drawn from underlying temporal distributions of varying complexity, from uniform to highly skewed or bimodal while also varying the error mapping that determined the performance feedback. Interval reproduction times were affected by both the distribution and feedback, in good agreement with a performance-optimizing Bayesian observer and actor model. Bayesian model comparison highlighted that subjects were integrating the provided feedback and represented the experimental distribution with a smoothed approximation. A nonparametric reconstruction of the subjective priors from the data shows that they are generally in agreement with the true distributions up to third-order moments, but with systematically heavier tails. In particular, higher-order statistical features (kurtosis, multimodality) seem much harder to acquire. Our findings suggest that humans have only minor constraints on learning lower-order statistical properties of unimodal (including peaked and skewed) distributions of time intervals under the guidance of corrective feedback, and that their behavior is well explained by Bayesian decision theory.

Boundary effects on the vibration statistics of a random plate

This paper considers the estimation of statistics of displacement of a vibrating rectangular plate with random wave scatterers. The influence of uncertainty is investigated using point impedance theory. Coherent boundary effects are seen, which decrease when the number of scatterers increases. The boundary effect is investigated using images and the first side and corner reflections are found to be a minimum requirement to estimate the spatial correlation. Statistics for point driven response are investigated under the assumption that the statistics of the natural frequencies follow those of the Gaussian Orthogonal Ensemble (GOE). The estimates are compared with Monte Carlo simulation results, and they show good agreement. © 2012 Elsevier Ltd. All rights reserved.

Numerical analysis of AC loss reduction in HTS superconducting coils using magnetic materials to divert flux

In this paper, the use of magnetic materials to divert flux in high-temperature superconductor superconducting coils and reduce transport ac loss is investigated. This particular technique is preferred over other techniques, such as striation, Roebel transposition, and twisted wires because it does not require modification to the conductor itself, which can be detrimental to the properties of the superconductor. The technique can also be implemented for existing coils. The analysis is carried out using a coil model based on the H formulation and implemented in comsol multiphysics. Both weakly and strongly magnetic materials are investigated, and it is shown that the use of such materials can divert flux and achieve a reduction in transport ac loss, which, in some cases, is quite significant. This analysis acts to provide a foundation for further optimization and experimental work in the future. © 2011 IEEE.

The experiment to evaluate the AC loss of 2G HTS windings in the application of rotating electric machines

This paper presents the design of an AC loss experiment using nitrogen boil-off method. This experiment is aimed at exploring the AC loss of HTS double race-track coils which will be installed on the rotor of a wind turbine generator. The operating environment is simulated by designing a cryostat with rotating magnetic field windings. Apart from the fact that the alternating magnetic field causes most of AC loss on the HTS coils, we also believe that the DC background field would be another important factor causing AC loss if the HTS coil is experiencing by both alternating magnetic field in the perpendicular direction and DC background field in the parallel direction. In order to perform the boil-off measurement, we present the method to estimate the heat leakage in the cryostat which might cause errors to the measurement. © 2011 IEEE.

Design methodology of HTS bulk machine for direct-driven wind generation

This paper introduces the design methodology of HTS bulk generator for direct-driven wind turbine. The trap field capability of HTS bulks offer the potential of maintaining similar or even higher magnetic loading level without the iron circuit in the generator. This so-called air-cored design can reduce the weight and increase the power outing per volume of the machine. The detailed design method of the air-cored HTS bulk machine is presented; 3D modeling is applied to consider the total trapped field of bulk arrays; a case study is performed to demonstrate the advantages of air-cored HTS bulk machine over conventional permanent magnet machine. Our results show that the air-cored HTS bulk machine has the potential to maintain the same magnetic loading level as that of the conventional permanent magnet machine. More importantly, it can reduce the total machine weight by 30%. © 2002-2011 IEEE.

High-precision digital lock-in measurements of critical current and AC loss in HTS 2G-Tapes

Application of High Temperature Superconducting (HTS) has been increasingly popular since the new superconducting materials were discovered. This paper presents a new high-precision digital lock-in measurement technique which is used for measuring critical current and AC loss of the 2nd Generation HTS tape. Using a lock-in amplifier and nano-voltage meter, we can resolve signals at nano-volt level, while using a specially designed compensation coil we can cancel out inductive by adjusting the coil inductance. Furthermore, a finer correction for the inductive component can be achieved by adjusting the reference phase of the lock-in amplifier. The critical current and AC loss measurement algorithms and hardware layout are described and analyzed, and results for both numerical and experimental data under varieties of frequencies are presented. © 2008 SICE.

Complex study of transport AC loss in various 2G HTS racetrack coils

HTS racetrack coils are becoming important elements of an emerging number of superconducting devices such as generators or motors. In these devices the issue of AC loss is crucial, as performance and cooling power are derived from this quantity. This paper presents a comparative study of transport AC loss in two different types of 2G HTS racetrack coils. In this study, both experimental measurements and computer simulation approaches were employed. All the experiments were performed using classical AC electrical method. The finite-element computer model was used to estimate electromagnetic properties and calculate transport AC loss. The main difference between the characterized coils is covered inside tape architectures. While one coil uses tape based on RABITS magnetic substrate, the second coil uses a non-magnetic tape. Ferromagnetic loss caused by a magnetic substrate is an important issue involved in the total AC loss. As a result, the coil with the magnetic substrate surprised with high AC loss and rather low performance. © 2013 Elsevier B.V. All rights reserved.

AC loss estimation of HTS armature windings for electric machines

This paper studies 2G high-temperature superconducting (HTS) coils for electric machine armature windings, using finite element method (FEM) and H formulation. A FEM model for 2G HTS racetrack coil is built in COMSOL, and is well validated by comparing calculated ac loss with experimental measurements. The FEM model is used to calculate transport loss in HTS armature windings, using air-cored design. We find that distributed winding used in conventional machine design is an effective way to reduce transport loss of HTS armature winding, in terms of air-cored design. Based on our study, we give suggestions on the design of low loss HTS armature winding. © 2002-2011 IEEE.

Complex study of transport AC loss in various 2G HTS racetrack coils

HTS racetrack coils are becoming important elements of an emerging number of superconducting devices such as generators or motors. In these devices the issue of AC loss is crucial, as performance and cooling power are derived from this quantity. This paper presents a comparative study of transport AC loss in two different types of 2G HTS racetrack coils. In this study, both experimental measurements and computer simulation approaches were employed. All the experiments were performed using classical AC electrical method. The finite-element computer model was used to estimate electromagnetic properties and calculate transport AC loss. The main difference between the characterized coils is covered inside tape architectures. While one coil uses tape based on RABITS magnetic substrate, the second coil uses a non-magnetic tape. Ferromagnetic loss caused by a magnetic substrate is an important issue involved in the total AC loss. As a result, the coil with the magnetic substrate surprised with high AC loss and rather low performance. © 2013 Elsevier B.V. All rights reserved.

Study by Hall probe mapping of the trapped flux modification produced by local heating in YBCO HTS bulks for different surface/volume ratios

The aim of this report is to compare the trapped field distribution under a local heating created at the sample edge for different sample morphologies. Hall probe mappings of the magnetic induction trapped in YBCO bulk samples maintained out of thermal equilibrium were performed on YBCO bulk single domains, YBCO single domains with regularly spaced hole arrays, and YBCO superconducting foams. The capability of heat draining was quantified by two criteria: the average induction decay and the size of the thermally affected zone caused by a local heating of the sample. Among the three investigated sample shapes, the drilled single domain displays a trapped induction which is weakly affected by the local heating while displaying a high trapped field. Finally, a simple numerical modelling of the heat flux spreading into a drilled sample is used to suggest some design rules about the hole configuration and their size. © 2005 IOP Publishing Ltd.