Following the guiding hypothesis in NLP, similar word frequency vectors may have similar implicatures, but some scholars are more inclined conversational implicatures cannot be obtained only through ...lexical features. To judge which view is more reasonable and explore the reasons for the divergence between them, whether conversational implicatures can be obtained only through lexical features is verified empirically. Main work of this paper includes: First, based on 600 corpora in the annotated dataset, the values of 20 lexical features of each corpus are obtained by automatic calculation. Second, meta-transformer of logistic regression for selecting features is adopted for feature selection and ranking. Third, after determining the features, the text is classified by the binomial logistic regression with the type of implicatures as labels. Fourth, results are tested for significance to identify relationships between variables. Experiments show that there is a statistical dependence between lexical features and conversational implicatures, and the text classification of implicatures can be performed only based on lexical features. In addition, the results of text classification will not be different due to the difference in context utterance or the type of implicature, and the text classification of implicatures only based on "response utterance" is more efficient.
This paper presents an energy-efficient visible light communication (VLC) receiver system-on-a-chip (SoC) that employs ambient light rejection (ALR) and post-equalization techniques for emerging ...light fidelity (Li-Fi) applications using ordinary phosphorescent white light-emitting diodes (LEDs). A current-reuse transimpedance amplifier is proposed for energy-efficient applications. An ALR unit is implemented to eliminate the potential DC interference under strong ambient light. A two-stage continuous-time linear equalizer is utilized to compensate for the limited bandwidth of white LEDs, which is below 3 MHz. Implemented in a 0.18 μm CMOS process, the receiver occupies an area of 0.7 × 0.4 mm 2 and consumes 2.2 mW of power at 24 Mb/s from a 1.8 V power supply. An IEEE 802.15.7 PHY-II compliant Li-Fi link that employs the proposed receiver SoC and a custom transmitter SoC is demonstrated based on 1-W phosphorescent white LEDs without using blue filtering, achieving a bit error rate of 1 × 10 -9 for data rates up to 24 Mb/s over 1.6 m distance, and 22 Mb/s over 2.7 m distance, with on-off keying modulation and 2 11 -1 pseudorandom binary sequence (PRBS-11) optical inputs. The receiver SoC achieves a bit efficiency six times better than that of the prior art using off-the-shelf discrete components, and can tolerate an ambient light level of 3500 lx. A figure of merit accommodating the most important system parameters is also proposed for a comprehensive comparison of different VLC systems.
In this Letter, a novel inverter-based trans-impedance amplifier (TIA) with enhanced gain and sensitivity is presented for Gb/s visible light communication (VLC). By employing capacitive feedback ...with a large negative equivalent capacitance to reduce the TIA input capacitance, the proposed TIA achieves a trans-impedance gain of 89.4 dBΩ with 5.7 dB improvement and an input referred noise current of 0.43 µArms with 1.8 dB improvement when compared to a reference TIA without capacitive feedback. Both the proposed TIA and the reference TIA have the same −3 dB bandwidth (BW) of 3 GHz and the same power consumption of 1 mW, and they are designed with a 40 nm CMOS process.
The organic acid crystal modifiers play an important role in the control of the crystal habit of α-hemihydrate gypsum (α-CaSO4·0.5H2O) from phosphogypsum, but the molecular structure characteristics ...of crystal modifiers have not been clarified, which makes it difficult to judge whether an organic acid has the ability to regulate the crystal habit of α-CaSO4·0.5H2O directly. In this work, the effect of organic acids with different molecular structures on the crystal habit of α-CaSO4·0.5H2O and its adsorption differences onto the α-CaSO4·0.5H2O surface were explored. The results show that the molecular structure characteristics of crystal modifiers contain two or more carboxylic groups (COOH) that are separated by two methylene or methine groups. Furthermore, organic acids with the regulation ability can adsorb on the surface of α-CaSO4·0.5H2O and change its growth habit. With the increase in the crystal modifier concentration, the α-CaSO4·0.5H2O crystals are shortened in length and enlarged in width, resulting in the decrease in aspect ratio and the increase in compressive strength. Conversely, when the adsorption of ineffective organic acids on the surface of α-CaSO4·0.5H2O was not detected, the α-CaSO4·0.5H2O crystals remained long hexagonal prisms. These results have guiding significance for the screening of novel organic acid crystal modifiers.
This paper presents an IEEE 802.15.7 Physical Layer I (PHY-I) standard compliant visible light communication (VLC) transmitter system-on-a-chip (SoC), enabling the use of ordinary white LED lights as ...beacons or broadcasters for location-based applications. The mixed-signal SoC integrates a baseband digital signal processing (DSP) unit, a VLC modulator, and a switching boost LED driver with an on-chip power MOSFET. The DSP unit supports various coding schemes as well as both the on-off keying (OOK) modulation and the variable pulse-position modulation specified in the aforementioned standard. The boost LED driver is designed to power a matrix of 4 × 5 LEDs using Li-ion batteries for portable applications. The SoC simultaneously supports VLC and LED illumination with nine dimming levels. Implemented in a 0.35-μm CMOS process with 20-V devices, the SoC achieves a measured VLC data rate of up to 266 kb/s at a package error rate (PER) <; 10% using a 2 11 -1 PRBS (pseudo random binary sequence) input. The communication distance measured is more than 2 m using no optical lens with the link efficiency of 5 nJ/bit. From an input at 3-5 V, the boost converter generates an output at 6-20 V with a 92% peak efficiency and an 8-W rating.
This paper presents the design and characterization of the first active matrix light-emitting diode (AMLED) microdisplay with an embedded visible light communication (VLC) transmitter, enabling LED ...digital signage for location-based applications such as information broadcasters and indoor positioning beacons. The driver system-on-a-chip (SoC) integrates four identical macro-cells, each containing a pixel driver array, a row driver, a column driver, and a first-in first-out memory, to drive a wide quarter-VGA (WQVGA) display featuring 400 × 240 blue micro-LED (μLED) pixels fabricated on a single gallium nitride (GaN) substrate. The size of each μLED pixel is 30 × 30 μm 2 . At the system level, pulse-width modulation (PWM) superimposed with on-off keying modulation is proposed to accomplish grayscale control for display and simultaneously transmit VLC signal by modulating the μLED array. At the circuit level, a pixel driver cell composed of three transistors and one capacitor (3T1C) with a novel VLC function is employed to implement the control scheme. Flip-Chip bonding is adopted to establish connections between the WQVGA microdisplay and the AMLED driver SoC. Implemented in a 0.5-μm 2P3M CMOS process, the driver SoC enables a high-resolution microdisplay module to achieve 4-bit grayscale at a 100-Hz frame rate, while supporting 1.25-Mb/s VLC for a bit error rate <;10 -5 up to 25-cm distance without a lens. When using optical lenses, the VLC distance is extended to >500 cm.
This paper presents, for the first time, a systematic approach to visible light communication (VLC) transceiver design based on an analytical optical wireless link budget study. To obtain the ...signal-to-noise ratio at the receiver, the received signal power is predicted by modeling the transmitted optical power and the channel path loss, while the input-referred noise is estimated by characterizing the noise contribution from each of the receiver building blocks. Based on the targeted bit error rate (BER) and communication distance, a VLC transceiver using discrete components and a fully integrated CMOS VLC transmitter compliant with the IEEE 802.15.7 Standard have been designed and tested. Experimental results show that the measured BER agrees well with the proposed model for both the systems, validating our design approach and the link budget analysis.
Design and synthesis of flexible and self-supporting electrode materials in high-performance lithium storage is significant for applications in the field of smart wearable devices. Herein, flexible ...carbon nanofiber membranes with uniformly distributed molybdenum dioxide (MoO2) nanocrystals are fabricated by a needlefree electrospinning method combined with the subsequent carbonization process, which exhibits outstanding structural stability under abrasion and deformation. The as-fabricated lithium-ion batteries (LIBs) exhibit a high discharge of 450 mAh g−1 after 500 cycles at 2000 mA g−1 by using the MoO2/C nanofiber membrane as the self-supporting anode. Further, the nanofibers structure remains intact after 500 cycles, which reflects the excellent stability of the materials. This study provides a simple and effective method for the preparation of MoO2/C nanofiber materials, which can not only maintain its excellent electrochemical and physical properties, but also easily realize large-scale production. It is undoubtedly beneficial for the development of flexible LIBs and smart wearable devices.
Mineral surface wettability and its regulation by the adsorption of collectors have an important influence on the flotation performance. The adsorption behavior of C18 fatty acid with different ...unsaturation and its effect on rhodochrosite wettability was investigated with surface tension, contact angle, and atomic force microscopy (AFM) measurements. The results indicated that rhodochrosite hydrophobicity increased with the increasing concentration of fatty acid, along with the maximum contact angle (θmax) between hemimicelle concentration (HMC) and critical micelle concentration (CMC). Oleic acid (OA), linoleic acid (LA), and α-linolenic acid (ALA) had a higher θmax than stearic acid (SA), but the value decreased with the increase of C=C bond number. Besides, preferential adsorption of unsaturated fatty acids on the liquid-air interface can be attributed to the molecule’s steric hindrance resulting from C=C double bond, and the θ kept almost invariant with a higher value of ΓLG than ΓSL until HMC. The oriented monolayer and bilayer structure of fatty acids formed gradually on rhodochrosite surface with increasing concentration. However, the θmax may not necessarily correspond to the beginning of bilayer formation. Cylindrical monolayer and bilayer micelles of SA molecules were observed on rhodochrosite surface at HMC and CMC, respectively. While bilayer structures of unsaturated fatty acids formed before complete coverage of monolayer on rhodochrosite surface because of surface heterogeneity. This work provided a good understanding on the adsorption mechanism of fatty acid on rhodochrosite for flotation.
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