135 research outputs found
Encyonema chebalingense sp. nov., a new freshwater diatom species (Cymbellales, Bacillariophyceae) from Guangdong Province, China
No full textHuang, Ruohan, Ma, Jin, Wang, Xianyun, Blanco, Saúl, Kociolek, John Patrick, Zhang, Wei (2021): Encyonema chebalingense sp. nov., a new freshwater diatom species (Cymbellales, Bacillariophyceae) from Guangdong Province, China. Phytotaxa 508 (1): 77-84, DOI: 10.11646/phytotaxa.508.1.7, URL: http://dx.doi.org/10.11646/phytotaxa.508.1.
Phase-rotation-aided relay selection in two-way decode-and-forward relay networks
No full textThis paper proposes a relay selection scheme that aims to improve the end-to-end symbol error rate (SER) performance of a two-way relay network (TWRN). The TWRN consists of two single-antenna sources and multiple relays employing decode-and-forward (DF) protocol. It is shown that the SER performance is determined by the minimum decision distance (DD) observed in the TWRN. However, the minimum DD is likely to be made arbitrarily small by channel fading. To tackle this problem, a phase rotation (PR) aided relay selection (RS) scheme is proposed to enlarge the minium DD, which in turn improves the SER performance. The proposed PR based scheme rotates the phases of the transmitted symbols of one source and of the selected relay according to the channel state information, aiming for increasing all DDs to be above a desired bound. The lower bound is further optimized by using a MaxMin-RS criterion associated with the channel gains. It is demonstrated that the PR aided MaxMin-RS approach achieves full diversity gain and an improved array gain. Furthermore, compared with the existing DF based schemes, the proposed scheme allows more flexible relay antenna configurations
FIGURES 16–21 in Encyonema chebalingense sp. nov., a new freshwater diatom species (Cymbellales, Bacillariophyceae) from Guangdong Province, China
No full textFIGURES 16–21. Encyonema chebalingense sp. nov. SEM images from type material, internal views. 16. Entire valve view. 17–21. Apex of valve with distal raphe ending terminating as a helictoglossa. Fig. 18. Valve center showing central nodule with proximal ends of the raphe hidden by siliceous covering. Figs 19–21. Distal raphe end showing helictoglossa. Scale bars = 1 μm (19–21), 2 μm (Fig.17–21): 2.5 μm (16).Published as part of Huang, Ruohan, Ma, Jin, Wang, Xianyun, Blanco, Saúl, Kociolek, John Patrick & Zhang, Wei, 2021, Encyonema chebalingense sp. nov., a new freshwater diatom species (Cymbellales, Bacillariophyceae) from Guangdong Province, China, pp. 77-84 in Phytotaxa 508 (1) on page 82, DOI: 10.11646/phytotaxa.508.1.7, http://zenodo.org/record/542579
Achieving full diversity in multi-antenna two-way relay networks via symbol-based physical-layer network coding
No full textThis paper considers physical-layer network coding (PNC) with M-ary phase-shift keying (MPSK) modulation in two-way relay channel (TWRC). A low complexity detection technique, termed symbol-based PNC (SPNC), is proposed for the relay. In particular, attributing to the outer product operation imposed on the superposed MPSK signals at the relay, SPNC obtains the network-coded symbol (NCS) straightforwardly without having to detect individual symbols separately. Unlike the optimal multi-user detector (MUD) which searches over the combinations of all users’ modulation constellations, SPNC searches over only one modulation constellation, thus simplifies the NCS detection. Despite the reduced complexity, SPNC achieves full diversity in multi-antenna relay as the optimal MUD does. Specifically, antenna selection based SPNC (AS-SPNC) scheme and signal combining based SPNC (SC-SPNC) scheme are proposed. Our analysis of these two schemes not only confirms their full diversity performance, but also implies when SPNC is applied in multi-antenna relay, TWRC can be viewed as an effective single-input multiple-output (SIMO) system, in which AS-PNC and SC-PNC are equivalent to the general AS scheme and the maximal-ratio combining (MRC) scheme. Moreover, an asymptotic analysis of symbol error rate (SER) is provided for SC-PNC considering the case that the number of relay antennas is sufficiently large
Task modulation of disyllabic spoken word recognition in Mandarin Chinese: a unimodal ERP study
No full textUsing unimodal auditory tasks of word-matching and meaning-matching, this study investigated how the phonological and semantic processes in Chinese disyllabic spoken word recognition are modulated by top-down mechanism induced by experimental tasks. Both semantic similarity and word-initial phonological similarity between the primes and targets were manipulated. Results showed that at early stage of recognition (similar to 150-250 ms), an enhanced P2 was elicited by the word-initial phonological mismatch in both tasks. In similar to 300-500 ms, a fronto-central negative component was elicited by word-initial phonological similarities in the word-matching task, while a parietal negativity was elicited by semantically unrelated primes in the meaning-matching task, indicating that both the semantic and phonological processes can be involved in this time window, depending on the task requirements. In the late stage (similar to 500-700 ms), a centro-parietal Late N400 was elicited in both tasks, but with a larger effect in the meaning-matching task than in the word-matching task. This finding suggests that the semantic representation of the spoken words can be activated automatically in the late stage of recognition, even when semantic processing is not required. However, the magnitude of the semantic activation is modulated by task requirements
Molecular beam optical zeeman spectroscopy of vanadium monoxide, VOa
No full textLike almost all astronomical studies, exoplanet investigations are observational endeavors that rely primarily on remote spectroscopic sensing to infer the physical properties of planets. Most exoplanet related information is inferred from to temporal variation of luminosity of the parent star. An effective method of monitoring this variation is via Magnetic Doppler Imaging (MDI)\footnote{O. Kochukhov, N. Rusomarov, J. A. Valenti, H. C. Stempels, F. Snik, M. Rodenhuis, N. Piskunov, V. Makaganiuk, C. U. Keller and C. M. Johns-Krull, Astron. Astrophys. 574 (Pt. 2), A79/71-A79/12 (2015).}, which uses optical polarimetry\footnote{S. V. Berdyugina, Astron. Soc. Pac. Conf. Ser. 437 (Solar Polarization 6), 219-235 (2011).} of paramagnetic molecules or atoms. One promising paramagnetic stellar absorption is the near infrared spectrum of VO\footnote{S. V. Berdyugina, P. A. Braun, D. M. Fluri and S. K. Solanki, Astron. Astrophys. 444 (3), 947-960 (2005).}. With this in mind, we have begun a project to record and analyze the field-free and Zeeman spectrum of the band. A cold (approx. 20 K) beam of VO was probed with a single frequency laser and detected using laser induced fluorescence. The determined spectral parameters will be discussed and compared to those extracted from the analysis of a hot spectrum\footnote{A. S. C. Cheung, P. G. Hajigeorgiou, G. Huang, S. Z. Huang and A. J. Merer, J. Mol. Spectrosc. 163 (2), 443-458 (1994).}.Made available in DSpace on 2017-01-26T21:40:15Z (GMT). No. of bitstreams: 3
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Previous issue date: 2016-06-2
Encyonema chebalingense W. Zhang & S. Blanco 2021, sp. nov.
No full textEncyonema chebalingense W.Zhang & S.Blanco sp. nov. Figs 1–21 Description:—LM: Valves distinctly asymmetrical and dorsiventral, semielliptical or semielliptical-lanceolate, dorsal margin clearly arched, ventral margin nearly straight or slightly concave. Both ends gradually narrowed, apices not or only slightly protracted, broadly to obtusely rounded (Figs 1–9). Length of the observed specimens 17.8–26.0 μm, width 5.2–6.7 μm, length/width ratio 3.4–3.9 (n=17). Raphe slightly inclined to the ventral margin, nearly straight and linear. The proximal raphe end is slightly curved to the dorsal margin, the end slit of the distal end is close to the valve edge and conspicuously curved to the ventral margin. Axial area narrow, conspicuously inclined to the ventral side, and one stria (sometimes two) on the middle ventral side is shorter. Striae radiate with areolae indistinguishable under LM. Terminal striae density 10–11 in 10 μm, becoming 8–10 in 10 μm toward the central area. SEM: Externally, the valve of E. chebalingense is flat and the transition from the valve face to the mantle is gradual (Figs 10, 11). No stigmoids are present in the central area (Figs 12, 13). The proximal ends of the raphe are clearly enlarged and inclined to the dorsal side, while terminal fissures are hooked to the ventral side of the valve at an angle of almost 90°. The axial area is narrow and linear (Figs 10, 11, 14, 15). Most of the striae are composed by single areolae of different sizes and shapes, mostly short lineolae or slit-like. The middle part of the ventral side has significantly shortened striae (Figs 10–13). Internally, the proximal raphe endings are hidden by an overgrowth of silica (Fig.18), distal raphe ends terminate in small helictoglossae (Figs 16, 17, 19–21). The uniseriate areolae of each stria are arranged between the interstria, and short tectullae project within the striae (Figs 16–20). Areolae 40–45 in 10 μm within ventral and dorsal striae. Type:— CHINA. Guangdong Province: Shixing County, Shaoguan City, upper reaches of Mojiang River, 24°43’21” N, 114°15’24” E. 357 m asl, Date: X.L. Lin August 23 2020. Etymology:—The specific epithet “ chebalingense ” refers to the place from which this new species was collected.Published as part of Huang, Ruohan, Ma, Jin, Wang, Xianyun, Blanco, Saúl, Kociolek, John Patrick & Zhang, Wei, 2021, Encyonema chebalingense sp. nov., a new freshwater diatom species (Cymbellales, Bacillariophyceae) from Guangdong Province, China, pp. 77-84 in Phytotaxa 508 (1) on pages 78-79, DOI: 10.11646/phytotaxa.508.1.7, http://zenodo.org/record/542579
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Look and listen : from semantic to spatial audio-visual perception
No full textUnderstanding scenes and events is inherently a multi-modal experience. We perceive the world by both looking and listening (and touching, smelling, and tasting). In particular, the sounds made by objects, whether actively generated or incidentally emitted, offer valuable signals about their physical properties and spatial locations—the cymbals crash on stage, the bird tweets up in the tree, the truck revs down the block, the silverware clinks in the drawer.
However, while recognition has made significant progress by "looking"—detecting objects, actions, or people based on their appearance—it often does not listen. In this thesis, I show that audio that accompanies visual scenes and events can be used as a rich source of training signal for learning (audio-)visual models. Particularly, I have developed computational models that leverage both the semantic and spatial signals in audio to understand people, places, and things from continuous multi-modal observations. Below, I summarize my key contributions along these two themes:
Audio as a semantic signal: First, I develop methods that learn how different objects sound by both looking at and listening to unlabeled video containing multiple sounding objects. I propose an unsupervised approach to separate mixed audio into its component sound sources by disentangling the audio frequency bases for detected visual objects. Next, I further propose a new approach that trains audio-visual source separation models on pairs of training videos. This co-separation framework permits both end-to-end training and learning object-level sounds from unlabeled videos of multiple sound sources. As an extension of the co-separation approach, then I study the classic cocktail party problem to separate voices from the speech mixture by leveraging the consistency between the speaker's facial appearance and their voice. The two modalities, vision and audition, are mutually beneficial. While visual objects are indicative of the sounds they make to enhance audio source separation, audio can also be informative of the visual events in videos. Finally, I propose a framework that uses audio as a semantic signal to help visual events classification. I design a preview mechanism to eliminate both short-term and long-term visual redundancies using audio for efficient action recognition in untrimmed video.
Audio as a spatial signal: Both audio and visual data also convey significant spatial information. The two senses naturally work in concert to interpret spatial signals. Particularly, the human auditory system uses two ears to extract individual sound sources from a complex mixture. Leveraging the spatial signal in videos, I devise an approach to lift a flat monaural audio signal to binaural audio by injecting the spatial cues embedded in the accompanying visual frames. When listening to the predicted binaural audio—the 2.5D visual sound—listeners can then feel the locations of the sound sources as they are displayed in the video. Beyond learning from passively captured video, I next explore the spatial signal in audio by deploying an agent to actively interact with the environment using audio. I propose a novel representation learning framework that learns useful visual features via echolocation by capturing echo responses in photo-realistic 3D indoor scene environments. Experimental results demonstrate that the image features learned from echoes are comparable or even outperform heavily supervised pre-training methods for multiple fundamental spatial tasks—monocular depth prediction, surface normal estimation, and visual navigation.
Our results serve as an exciting prompt for future work leveraging both the visual and audio modalities. Motivated by how we humans perceive and act in the world by making use of all our senses, the long-term goal of my research is to build systems that can perceive as well as we do by combining all the multisensory inputs. In the last chapter of my thesis, I outline the potential future research directions that I want to pursue beyond my Ph.D. dissertation.Computer Scienc
Functionalisation of Liquid Metal Droplets by Surface and Interface Engineering and Electrification
No full textLiquid metals, particularly gallium-based alloys, have attracted increasing attention as a class of functional materials due to their excellent electrical conductivity, fluidity, and tunable surface chemistry. This thesis explores strategies to engineer tunable interfaces in liquid metals through alloy composition modulation and particle functionalisation, ultimately enabling the development of reconfigurable electroluminescent display systems.
In Chapters 1 and 2, the background and fundamental principles of gallium-based liquid metals, surface modulation, and electric discharge-induced electroluminescence are introduced through a critical review of relevant literature.
In Chapter 3, the author investigates the influence of minor alloying elements (Sn, Bi, Zn) on the electrocapillarity and electrochemical surface behaviour of gallium (Ga). By systematically analysing how trace elements affect surface tension, wetting dynamics, and oxidation-induced structures, this study reveals the underlying mechanisms that govern surface reactivity and electric field responses in Ga-based liquid metals.
In Chapter 4, the author demonstrates a particle-functionalized liquid metal platform by embedding electroluminescent phosphor particles (e.g., ZnS:Cu) into the oxide shell of EGaIn droplets, forming liquid metal marbles. These marbles enable dynamic visualisation of electric discharge paths under applied voltage, offering a novel approach to spatially map and manipulate discharge trajectories.
In Chapter 5, building upon the discharge-path visualisation strategy established in Chapter 4, the author further develops a reconfigurable multi-colour display platform using phosphor-coated liquid metal marbles. This chapter extends the concept from single-colour discharge visualisation to full-spectrum, programmable colour display. By incorporating red, green, and blue phosphors in controlled ratios, additive colour mixing is achieved without the need for physically separated subpixels.
In Chapter 6, the thesis concludes by summarizing the major findings and outlining future research directions. The results collectively establish a unified interface engineering framework for gallium-based liquid metals, with potential applications ranging from fundamental electrochemical modulation to advanced soft optoelectronic systems
Robust Lane Detection through Self Pre-training with Masked Sequential Autoencoders and Fine-tuning with Customized PolyLoss
No full textLane detection is crucial for vehicle localization which makes it the foundation for automated driving and many intelligent and advanced driving assistant systems. Available vision-based lane detection methods do not make full use of the valuable features and aggregate contextual information, especially the interrelationships between lane lines and other regions of the images in continuous frames. To fill this research gap and upgrade lane detection performance, this paper proposes a pipeline consisting of self pre-training with masked sequential autoencoders and fine-tuning with customized PolyLoss for the end-to-end neural network models using multi-continuous image frames. The masked sequential autoencoders are adopted to pretrain the neural network models with reconstructing the missing pixels from a random masked image as the objective. Then, in the fine-tuning segmentation phase where lane detection segmentation is performed, the continuous image frames are served as the inputs, and the pre-trained model weights are transferred and further updated using the backpropagation mechanism with customized PolyLoss calculating the weighted errors between the output lane detection results and the labeled ground truth. Extensive experiment results demonstrate that, with the proposed pipeline, the lane detection model performance on both normal and challenging scenes can be advanced beyond the state-of-the art results, while the training time can be substantially shortened
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