Mobile Formation Coordination and Tracking Control for Multiple Non-holonomic Vehicles

This paper addresses forward motion control for trajectory tracking and mobile formation coordination for a group of non-holonomic vehicles on SE(2). Firstly, by constructing an intermediate attitude variable which involves vehicles' position information and desired attitude, the translational and rotational control inputs are designed in two stages to solve the trajectory tracking problem. Secondly, the coordination relationships of relative positions and headings are explored thoroughly for a group of non-holonomic vehicles to maintain a mobile formation with rigid body motion constraints. We prove that, except for the cases of parallel formation and translational straight line formation, a mobile formation with strict rigid-body motion can be achieved if and only if the ratios of linear speed to angular speed for each individual vehicle are constants. Motion properties for mobile formation with weak rigid-body motion are also demonstrated. Thereafter, based on the proposed trajectory tracking approach, a distributed mobile formation control law is designed under a directed tree graph. The performance of the proposed controllers is validated by both numerical simulations and experiments

Deep learning for extracting protein-protein interactions from biomedical literature

State-of-the-art methods for protein-protein interaction (PPI) extraction are primarily feature-based or kernel-based by leveraging lexical and syntactic information. But how to incorporate such knowledge in the recent deep learning methods remains an open question. In this paper, we propose a multichannel dependency-based convolutional neural network model (McDepCNN). It applies one channel to the embedding vector of each word in the sentence, and another channel to the embedding vector of the head of the corresponding word. Therefore, the model can use richer information obtained from different channels. Experiments on two public benchmarking datasets, AIMed and BioInfer, demonstrate that McDepCNN compares favorably to the state-of-the-art rich-feature and single-kernel based methods. In addition, McDepCNN achieves 24.4% relative improvement in F1-score over the state-of-the-art methods on cross-corpus evaluation and 12% improvement in F1-score over kernel-based methods on "difficult" instances. These results suggest that McDepCNN generalizes more easily over different corpora, and is capable of capturing long distance features in the sentences.Comment: Accepted for publication in Proceedings of the 2017 Workshop on Biomedical Natural Language Processing, 10 pages, 2 figures, 6 table

Single-molecule detection of molecular beacons generated from LDR on thermoplastic microfluidic device for bioanalysis

Current clinical techniques for nucleic acid detection and analysis often involve PCR, lacking adequate specificity or sensitivity to meet the stringent requirements in certain applications. This research aims to develop an innovative molecular assay and the associated hardware to rapidly signal the presence of certain targets using reporter sequence found in their genome without requiring PCR. This assay coupled the sensitivity of single-pair fluorescence resonance energy transfer (spFRET) with the specificity of ligase detection reaction (LDR) to provide near real-time readout of target biomarkers. Heightened concerns on potential bioterrorism threats, such as rapid dissemination of pathogenic bacteria or viruses into water and/or food supplies, demand fast detection strategies. In this work, a pair of strain-specific primers was designed based on the 16S rRNA gene and were end-labeled with a donor (Cy5) and acceptor (Cy5.5) dyes. In the presence of the target bacterium, the primers were joined using LDR to form a reverse molecular beacon (rMB), thus bringing Cy5 and Cy5.5 into close proximity to allow FRET to occur. These rMBs were analyzed using single-molecule detection of the FRET pairs (spFRET). The LDR was performed in a Cyclic Olefin Copolymer (COC) microfluidic device equipped with 2 or 20 thermal cycles in a continuous flow format. Single-molecule photon bursts from the resulting rMBs were detected on-chip and registered using a laser-induced fluorescence (LIF) instrument. The presence of target pathogens could be reported in as little as 2.6 min using spFRET. In another development, a similar assay format was utilized to quantify mRNA expression levels of MMP-7 gene, which is highly relevant to invasion, metastasis and progression of a variety of tumors. HT-29 cells were found to express the highest levels of MMP-7 transcripts among the studied cell lines using LDR primers specific to MMP-7 gene. This observation is consistent with the results obtained with RT-qPCR. The LDR-spFRET assay was also used for stroke subtyping by designing primers specific to AMPH gene and using a microfluidic chip with tapered detection window to improve sampling efficiency. The detection could be completed in 15 min with extended readout time to glean low copy number transcripts

A novel hydrogen and oxygen generation system

This study examined the three phases of the sorption-enhanced SMR process for H2 production: production of low-CO hydrogen using the standard Ni-based reforming catalyst and high purity CaO sorbent precursor, evaluation of combined reforming catalyst-sorbent samples supplied by TDA, and an Aspen simulation study of the process for simultaneous production of H2 and O2. The production of low-CO (\u3c20ppmv) hydrogen was studied using the single-step sorption-enhanced steam methane reforming process. The effects of temperature, volumetric feed rate, and feed gas composition on the purity of H2 and the content of CO were investigated. The feasibility of producing 95+% H2 with CO content of less than 20ppmv was experimentally proven in a test at 480¡ãC and 5 atm using a commercial Ni-based catalyst and the calcium-based CO2 sorbent. The feed gas contained 20% CH4 and 80% H2O, while the product gas contained 97.8% H2 and 17 ppmv CO. With this low CO concentration, the product can be used in a proton exchange membrane (PEM) fuel cell without further purification. The catalyst-sorbent samples from TDA Research Inc. were extensively studied and evaluated with respect to their performance in the steam-reforming reaction using both the fixed-bed reactor system and TGA. The activity of the catalyst samples having different compositions was examined and compared at different temperatures and space velocities using a feed gas containing 11.1% CH4 with a steam-to-carbon (S/C) ratio of 3.0. The sorption activity and durability was also examined in the TGA system. The overall hydrogen and oxygen co-production process was studied and evaluated using the Aspen Plus simulator. Material and energy balance calculations showed that this system can produce 99+% purity hydrogen and oxygen simultaneously with efficient energy integration. This process is balanced on power consumption and generation, so no external power is required

Field-effect mobility enhanced by tuning the Fermi level into the band gap of Bi2Se3

By eliminating normal fabrication processes, we preserve the bulk insulating state of calcium-doped Bi2Se3 single crystals in suspended nanodevices, as indicated by the activated temperature dependence of the resistivity at low temperatures. We perform low-energy electron beam irradiation (<16 keV) and electrostatic gating to control the carrier density and therefore the Fermi level position in the nanodevices. In slightly p-doped Bi2-xCaxSe3 devices, continuous tuning of the Fermi level from the bulk valence band to the band-gap reveals dramatic enhancement (> a factor of 10) in the field-effect mobility, which suggests suppressed backscattering expected for the Dirac fermion surface states in the gap of topological insulators

Arbitrary Configuration Stabilization Control for Nonholonomic Vehicle with Input Saturation:a c-Nonholonomic Trajectory Approach

This paper addresses the saturated stabilization control problem for nonholonomic vehicles with a novel c-nonholonomic trajectory approach on SE(2), with applications to automatic parking. Firstly, by defining the cnonholonomic configuration, a c-nonholonomic trajectory is obtained which provides a novel approach to design stabilization controller to reach an arbitrary configuration. Secondly, a global discontinuous time-invariant feedback controller with input saturation is proposed which does not involve time signal information, and its convergence is illustrated by a Lyapunov function approach. Thereafter, the motion trajectory of the proposed controller is analyzed, and the application scenario in automatic parking with the approximate desired trajectory is demonstrated. Finally, the performance of the proposed controller is validated by both numerical simulations and experiments.</p