Waveguide Panel Display Using Electromechanical Spatial Modulators

A novel micro‐electro‐mechanical system (MEMS) approach in waveguide panel displays (WPD) is described. High efficiency electromechanical spatial modulators, based on the use of frustrated total internal reflection, were demonstrated. Potential applications of the new display in HDTV using solid‐state light emitting diode (LED) as a light source are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92009/1/1.1833659.pd

Co-interest Person Detection from Multiple Wearable Camera Videos

Wearable cameras, such as Google Glass and Go Pro, enable video data collection over larger areas and from different views. In this paper, we tackle a new problem of locating the co-interest person (CIP), i.e., the one who draws attention from most camera wearers, from temporally synchronized videos taken by multiple wearable cameras. Our basic idea is to exploit the motion patterns of people and use them to correlate the persons across different videos, instead of performing appearance-based matching as in traditional video co-segmentation/localization. This way, we can identify CIP even if a group of people with similar appearance are present in the view. More specifically, we detect a set of persons on each frame as the candidates of the CIP and then build a Conditional Random Field (CRF) model to select the one with consistent motion patterns in different videos and high spacial-temporal consistency in each video. We collect three sets of wearable-camera videos for testing the proposed algorithm. All the involved people have similar appearances in the collected videos and the experiments demonstrate the effectiveness of the proposed algorithm.Comment: ICCV 201

Carbon monoxide oxidation under transient conditions: A fourier-transform infrared transmission spectroscopy study

In contrast to the apparent simplicity of the overall reaction, oxidation of CO over Pt/A2O3 is known to present complex behavior. Self-sustained oscillations, hysteresis loops in conversion, and enormous rate enhancements under forced feed concentration cycling have been observed. In this study the dynamic behavior of the IR-active surface CO species was followed with a fast-scan Fourier-Transform Infrared (FTIR) during transient response and periodic operation. Depending on the conditions, up to four linearly adsorbed CO bands at 2123, 2092, 2073, and 2061 cm-1, and a bridge-bonded CO band at 1850 cm- were observed. The time-averaged and transient intensities of the bands were found to be significantly different during periodic operation as compared to steady state. Linearly adsorbed CO on metallic platinum (2073 cm-) was found to have the fastest response to changes in the gas-phase concentration. It was also observed that CO adsorbed on platinum oxide is very stable and does not take part in the reaction to any appreciable extent. CO2 production rates during periodic operation were found to correlate extremely well with the integrated total absorbance of the 2092-cm- band, assigned to CO linearly adsorbed on a platinum atom sharing an oxygen with a neighbor. Based on the experimental observations a detailed mechanism of CO oxidation on platinum is proposed. The model can successfully explain the enormous rate enhancements observed during periodic operation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25628/1/0000178.pd

AACC: Asymmetric Actor-Critic in Contextual Reinforcement Learning

Reinforcement Learning (RL) techniques have drawn great attention in many challenging tasks, but their performance deteriorates dramatically when applied to real-world problems. Various methods, such as domain randomization, have been proposed to deal with such situations by training agents under different environmental setups, and therefore they can be generalized to different environments during deployment. However, they usually do not incorporate the underlying environmental factor information that the agents interact with properly and thus can be overly conservative when facing changes in the surroundings. In this paper, we first formalize the task of adapting to changing environmental dynamics in RL as a generalization problem using Contextual Markov Decision Processes (CMDPs). We then propose the Asymmetric Actor-Critic in Contextual RL (AACC) as an end-to-end actor-critic method to deal with such generalization tasks. We demonstrate the essential improvements in the performance of AACC over existing baselines experimentally in a range of simulated environments

Long Term Stability of Nanowire Nanoelectronics in Physiological Environments

Nanowire nanoelectronic devices have been exploited as highly sensitive subcellular resolution detectors for recording extracellular and intracellular signals from cells, as well as from natural and engineered/cyborg tissues, and in this capacity open many opportunities for fundamental biological research and biomedical applications. Here we demonstrate the capability to take full advantage of the attractive capabilities of nanowire nanoelectronic devices for long term physiological studies by passivating the nanowire elements with ultrathin metal oxide shells. Studies of Si and Si/aluminum oxide (Al2O3) core/shell nanowires in physiological solutions at 37 °C demonstrate long-term stability extending for at least 100 days in samples coated with 10 nm thick Al2O3 shells. In addition, investigations of nanowires configured as field-effect transistors (FETs) demonstrate that the Si/Al2O3 core/shell nanowire FETs exhibit good device performance for at least 4 months in physiological model solutions at 37 °C. The generality of this approach was also tested with in studies of Ge/Si and InAs nanowires, where Ge/Si/Al2O3 and InAs/Al2O3 core/shell materials exhibited stability for at least 100 days in physiological model solutions at 37 °C. In addition, investigations of hafnium oxide-Al2O3 nanolaminated shells indicate the potential to extend nanowire stability well beyond 1 year time scale in vivo. These studies demonstrate that straightforward core/shell nanowire nanoelectronic devices can exhibit the long term stability needed for a range of chronic in vivo studies in animals as well as powerful biomedical implants that could improve monitoring and treatment of disease

Multifunctional three-dimensional macroporous nanoelectronic networks for smart materials

Seamless and minimally-invasive integration of three-dimensional (3D) electronic circuitry within host materials could enable the development of materials systems that are self- monitoring and allow for communication with external environments. Here, we report a general strategy for preparing ordered 3D interconnected and addressable macroporous nanoelectronic networks from ordered two-dimensional (2D) nanowire nanoelectronic “precursors”, which are fabricated by conventional lithography. The 3D networks have porosities larger than 99%, contain ca. 100’s of addressable nanowire devices, and have feature sizes from the 10 micron scale (for electrical and structural interconnections) to the 10 nanometer scale (for device elements). The macroporous nanoelectronic networks were merged with organic gels and polymers to form hybrid materials in which the basic physical and chemical properties of the host were not substantially altered, and electrical measurements further show a > 90% yield of active devices in the hybrid materials. The positions of the nanowire devices were located within 3D hybrid materials with ca. 14 nm resolution through simultaneous nanowire device photocurrent/confocal microscopy imaging measurements. In addition, we explored functional properties of these hybrid materials, including (i) mapping time-dependent pH changes throughout a nanowire network/agarose gel sample during external solution pH changes, and (ii) characterizing the strain field in a hybrid nanoelectronic elastomer structures subject to uniaxial and bending forces. The seamless incorporation of active nanoelectronic networks within 3D materials opens up a powerful approach to smart materials in which the capabilities of multi- functional nanoelectronics allow for active monitoring and control of host systems.Chemistry and Chemical BiologyEngineering and Applied Science

Implementation of Active Damping Control Methodology on Modular Multilevel Converter(MMC)-Based Arbitrary Wave Shape Generator Used for High Voltage Testing

In order to damp the resonance in the MMC-based Arbitrary Wave shape Generator (AWG) used for high voltage testing, an active damping control methodology is proposed in this paper instead of the passive damping with an arm resistor. It is vital to ensure the system’s stability when such an active damping closed loop control is implemented. Consequently, optimal parameters of a PI controller are designed by analyzing the stability margins of the involved transfer function using Bode-Plots. The performance of the designed active damping control methodology and the PI controller have been demonstrated with a 50 Hz sinusoidal waveform and arbitrary waveforms such as triangular, trapezoidal, and complex waveforms in MATLAB-Simulink. These results proves that the output voltage can track the reference without any reasonable error and does not contain any resonant frequency. Additionally, the Total Harmonic Distortion (THD) of the sinusoidal waveform and other arbitrary waveforms is less than 1% with the Phase Shift Carrier (PSC) modulation technique

Exploratory analysis of the position of Chinese cities as international tourism hubs: product destination versus business environment internationalization

This paper measures the level of tourism internationalization of 50 major cities in Mainland China by analyzing their connectivity as international tourism hubs. A typology of cities is presented based on a comparison of their ‘product destination internationalization’ and ‘business environment internationalization’ in the tourism sector. Results are interpreted in the context of three dimensions of the internationalization of the Chinese economy: the imbalanced development of the space-economy; the uneven impact of policy plans and mechanisms; and the imprint of spatio-political hierarchies. We discuss how this study can be complemented with research using other spatial imageries, and used as the starting point for further comparative studies on tourism internationalization in other geographical contexts