56 research outputs found

    Gender Difference of Unconscious Attentional Bias in High Trait Anxiety Individuals

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    By combining binocular suppression technique and a probe detection paradigm, we investigated attentional bias to invisible stimuli and its gender difference in both high trait anxiety (HTA) and low trait anxiety (LTA) individuals. As an attentional cue, happy or fearful face pictures were presented to HTAs and LTAs for 800 ms either consciously or unconsciously (through binocular suppression). Participants were asked to judge the orientation of a gabor patch following the face pictures. Their performance was used to measure attentional effect induced by the cue. We found gender differences of attentional effect only in the unconscious condition with HTAs. Female HTAs exhibited difficulty in disengaging attention from the location where fearful faces were presented, while male HTAs showed attentional avoidance of it. Our results suggested that the failure to find attentional avoidance of threatening stimuli in many previous studies might be attributed to consciously presented stimuli and data analysis regardless of participants' gender. These findings also contributed to our understanding of gender difference in anxiety disorder

    Study on Photon Transport Problem Based on the Platform of Molecular Optical Simulation Environment

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    As an important molecular imaging modality, optical imaging has attracted increasing attention in the recent years. Since the physical experiment is usually complicated and expensive, research methods based on simulation platforms have obtained extensive attention. We developed a simulation platform named Molecular Optical Simulation Environment (MOSE) to simulate photon transport in both biological tissues and free space for optical imaging based on noncontact measurement. In this platform, Monte Carlo (MC) method and the hybrid radiosity-radiance theorem are used to simulate photon transport in biological tissues and free space, respectively, so both contact and noncontact measurement modes of optical imaging can be simulated properly. In addition, a parallelization strategy for MC method is employed to improve the computational efficiency. In this paper, we study the photon transport problems in both biological tissues and free space using MOSE. The results are compared with Tracepro, simplified spherical harmonics method (SPn), and physical measurement to verify the performance of our study method on both accuracy and efficiency

    Qualitative Simulation of Photon Transport in Free Space Based on Monte Carlo Method and Its Parallel Implementation

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    During the past decade, Monte Carlo method has obtained wide applications in optical imaging to simulate photon transport process inside tissues. However, this method has not been effectively extended to the simulation of free-space photon transport at present. In this paper, a uniform framework for noncontact optical imaging is proposed based on Monte Carlo method, which consists of the simulation of photon transport both in tissues and in free space. Specifically, the simplification theory of lens system is utilized to model the camera lens equipped in the optical imaging system, and Monte Carlo method is employed to describe the energy transformation from the tissue surface to the CCD camera. Also, the focusing effect of camera lens is considered to establish the relationship of corresponding points between tissue surface and CCD camera. Furthermore, a parallel version of the framework is realized, making the simulation much more convenient and effective. The feasibility of the uniform framework and the effectiveness of the parallel version are demonstrated with a cylindrical phantom based on real experimental results

    Current Status and Prospect of Recycling Technology of Wind Turbine Blades

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    [Introduction] The growth of wind power industry is accelerating faster than ever worldwide, at the same time, the waste generation from end-of-life wind turbine blades is expected to peak in recent years. Efficient recycling of end-of-life wind turbine blades has become a key issue affecting the sustainable development of the wind power industry and its low-carbon-footprint target. [Method] Traditionally, majority of the end-of-life blades were either buried or incinerated after being dismantled, causing resources wasting and severe environmental problems. In this context, this paper reviewed the mainstream domestic and international recycling processes of end-of-life wind turbine blades such as mechanical recycling, pyrolysis, chemical recycling and comprehensive recycling, and analyzed their corresponding advantages and disadvantages. [Result] By summarizing the industrial recycling application scenarios, this paper provides suggestions and prospects for the prospective recycling market of the end-of-life wind turbine blades. [Conclusion] Wind power industry plays an important role in realizing the "carbon-peaking and carbon-neutrality" goals through assisting in implementation of the energy-conservation and emission-reduction strategy. However, the wind turbine blade recycling market is currently in the exploratory stage with medium and small-size, there is an urgent need for policies, standards and technology development to help with its large scale industrialization. This paper illustrates current status and development trend of domestic and international recycling technology and application scenarios of end-of-life wind turbine blades, and aims to provide the scientific references for the sustainable and low-carbon development of the wind power industry

    The Solenoidal Large Intensity Device (SoLID) for JLab 12 GeV

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    The Solenoidal Large Intensity Device (SoLID) is a new experimental apparatus planned for Hall A at the Thomas Jefferson National Accelerator Facility (JLab). SoLID will combine large angular and momentum acceptance with the capability to handle very high data rates at high luminosity. With a slate of approved high-impact physics experiments, SoLID will push JLab to a new limit at the QCD intensity frontier that will exploit the full potential of its 12 GeV electron beam. In this paper, we present an overview of the rich physics program that can be realized with SoLID, which encompasses the tomography of the nucleon in 3-D momentum space from Semi-Inclusive Deep Inelastic Scattering (SIDIS), expanding the phase space in the search for new physics and novel hadronic effects in parity-violating DIS (PVDIS), a precision measurement of J/ψJ/\psi production at threshold that probes the gluon field and its contribution to the proton mass, tomography of the nucleon in combined coordinate and momentum space with deep exclusive reactions, and more. To meet the challenging requirements, the design of SoLID described here takes full advantage of recent progress in detector, data acquisition and computing technologies. In addition, we outline potential experiments beyond the currently approved program and discuss the physics that could be explored should upgrades of CEBAF become a reality in the future.Comment: This white paper for the SoLID program at Jefferson Lab was prepared in part as an input to the 2023 NSAC Long Range Planning exercise. To be submitted to J. Phys.

    Precision measurements of A1N in the deep inelastic regime

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    We have performed precision measurements of the double-spin virtual-photon asymmetry A1A1 on the neutron in the deep inelastic scattering regime, using an open-geometry, large-acceptance spectrometer and a longitudinally and transversely polarized 3He target. Our data cover a wide kinematic range 0.277≤x≤0.5480.277≤x≤0.548 at an average Q2Q2 value of 3.078 (GeV/c)2, doubling the available high-precision neutron data in this x range. We have combined our results with world data on proton targets to make a leading-order extraction of the ratio of polarized-to-unpolarized parton distribution functions for up quarks and for down quarks in the same kinematic range. Our data are consistent with a previous observation of anA1n zero crossing near x=0.5x=0.5. We find no evidence of a transition to a positive slope in(Δd+Δd¯)/(d+d¯) up to x=0.548x=0.548

    Multidimensional Control of Repeating Unit/Sequence/Topology for One-Step Synthesis of Block Polymers from Monomer Mixtures

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    Synchronously and thoroughly adjusting the chemical structure difference between two blocks of the diblock copolymer is very useful for designing materials but difficult to achieve via self-switchable alternating copolymerization. Here, we report self-switchable alternating copolymerization from a mixture of two different cyclic anhydrides, epoxides, and oxetanes, where a simple alkali metal carboxylate catalyst switches between ring-opening alternating copolymerization (ROCOP) of cyclic anhydrides/epoxides and ROCOP of cyclic anhydrides/oxetanes, resulting in the formation of a perfect block tetrapolymer. By investigating the reactivity ratio of these comonomers, a reactivity gradient was established, enabling the precise synthesis of block copolymers with synchronous adjustment of each unit's chemical structure/sequence/topology. Consequently, a diblock tetrapolymer with two glass transition temperatures (T-g) can be easily produced by adjusting the difference in chemical structures between the two blocks

    Polyether/Polythioether Synthesis via Ring-Opening Polymerization of Epoxides and Episulfides Catalyzed by Alkali Metal Carboxylates

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    Alkali metal carboxylates were evaluated as simple and green catalysts for the ring-opening polymerization (ROP) of various epoxides (e.g., alkyl-substituted epoxides and glycidyl ethers) and episulfides (alkyl-substituted episulfides and thioglycidyl ethers). The thus-produced functional polyethers (end-functionalized polyethers, block copolyethers, polyether- polyester block copolymers, topologically unique polyethers, and isotactic-enriched polyethers) and polythioethers featured well-defined structures and controlled molecular weights (Mn,SEC = 1.0-32 kg mol-1). The most effective catalyst was identified as cesium pivalate, and the variation of carboxylate moieties and alkali metal cations enabled the tuning of acid/base character-istics and thus allowed one to control polymerization behavior and expand the scope of functional monomers and initiators. Kinetic analysis confirmed the controlled/living nature of the polymerization process, while mechanistic studies revealed that carboxylate moieties did not directly initiate the ring-opening of epoxide monomers via nucleophilic attack but rather activated the alcohol initiators/chain ends via H-bonding and thus rendered the corresponding OH groups sufficiently nucleophilic to attack the alkali metal cation-activated epoxides

    Synthesis of hyperbranched polyesters via the ring-opening alternating copolymerisation of epoxides with a cyclic anhydride having a carboxyl group

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    Hyperbranched polyesters (HBPEs) are well-known interesting materials used in many fields. However, the known synthetic approaches for HBPEs lack versatility. Herein, we report a novel synthetic approach for an HBPE via ring-opening alternating copolymerisation (ROAC) using epoxides and trimellitic anhydride (TA) as the latent difunctional and trifunctional monomers, respectively. Caesium pivalate-catalysed ROACs of TA and excess epoxides were performed in the presence of an alcohol initiator at 80 degrees C in bulk. The obtained products, together with their linear counterparts (i.e., poly(phthalic anhydride-alt-epoxide) s), were characterised by NMR, viscometry, and light scattering. The results supported the successful synthesis of hyperbranched poly(TA-alt-epoxide)s. The versatility of the present HBPE synthesis was demonstrated by applying a range of alcohol initiators, such as typical diol and functional alcohols (e.g., poly (ethylene glycol) as a mono-alcohol or diol, and azido-/alkene-functionalised alcohols as another mono-alcohol), leading to HBPE-based block copolymers and functional HBPEs. Various epoxides, such as mono- and disubstituted alkylene oxides, glycidyl ether, and glycidyl amine, were found to be applicable in the present polymerisation system, which successfully produced HBPEs with different properties depending on the resulting backbone structure of the polymer

    Experimental Research on the Rotating Stall of a Pump Turbine in Pump Mode

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    The rotating stall is an unstable flow phenomenon of pump turbines in pump mode, which is of increasing concern to scientists and engineers working on pump turbines. However, at present, various studies are carried out based on CFD (computational fluid dynamics) simulation, while directly measured data and experimental research on flow fields are seldom reported. By utilizing PIV (particle image velocimetry) measuring equipment, the flow field within the guide vane zone of a low specific speed pump turbine in pump mode was measured. By measuring and analyzing the transient flow field, the evolutionary process of the rotating stall within the guide vane passages was determined. We found that for all three tested guide vane openings, regardless of whether the positive slope appeared or not, a pre-stall operating point was found for each opening in the process of decreasing the flow rate. The analysis of the loss within the flow field indicated that the dissipation-induced loss increased greatly after the rotating stall appeared. The pump performance curves at the three guide vane openings showed an inflection at the pre-stall point. When the flow rate is larger than that of the pre-stall point, the head of the pump turbine dramatically increases as the flow rate decreases. However, when the flow rate is smaller than the pre-stall point, such increases noticeably slows down. The research results showed that whether the positive slope on the pump performance curve occurred or not, instability caused by the rotating stall should be of great concern
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