73 research outputs found

    A combined method for gas-bearing layer identification in a complex sandstone reservoir

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    Langgu Depression is a mature oil and gas exploration area with complicated lithological and physical properties. The varying formation fluid, low-resistivity hydrocarbon-bearing reservoirs, and non-uniform logging series greatly increase the difficulty of gas reservoir identification. The Monte Carlo method is employed to simulate the neutron–gamma logging responses to gas saturation and the influential factors. According to the result, a new gas identification chart eliminating the influence of porosity and formation water salinity is proposed to identify gas reservoirs in the old wells. At the same time, a fluid factor extracted from array acoustic logging and core measurement data is sensitive to the development of gas-bearing layers and useful for the identification of gas reservoirs in the new wells with array acoustic logging. The field examples show that the new combined method greatly improves the ability to identify gas-bearing layers and works well in old well reexamination and new well interpretation

    Practical Quantum Simulation of Non-Hermitian Dynamics

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    Non-Hermitian quantum systems have recently attracted considerable attentions due to their exotic properties. Though many experimental realizations of non-Hermitian systems have been reported, the non-Hermiticity usually resorts to the hard-to-control environments. An alternative approach is to use quantum simulation with the closed system, whereas how to simulate general non-Hermitian Hamiltonian dynamics remains a great challenge. To tackle this problem, we propose a protocol by combining a dilation method with the variational quantum algorithm. The dilation method is used to transform a non-Hermitian Hamiltonian into a Hermitian one through an exquisite quantum circuit, while the variational quantum algorithm is for efficiently approximating the complex entangled gates in this circuit. As a demonstration, we apply our protocol to simulate the dynamics of an Ising chain with nonlocal non-Hermitian perturbations, which is an important model to study quantum phase transition at nonzero temperatures. The numerical simulation results are highly consistent with the theoretical predictions, revealing the effectiveness of our protocol. The presented protocol paves the way for practically simulating general non-Hermitian dynamics in the multi-qubit case.Comment: 9 pages, 5 figure

    The deubiquitinase USP6 affects memory and synaptic plasticity through modulating NMDA receptor stability

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    人类与其他动物相比的重要区别在于人类拥有高等认知能力,这种能力集中体现在学习记忆和语言表达方面。厦门大学医学院神经科学研究所王鑫教授团队发现人科动物特异性基因USP6作为一个新的NMDA受体调控因子,可通过去泛素化途径调节NMDA型谷氨酸受体的降解和稳定性,进而调控突触可塑性和学习记忆能力。 本研究工作由王鑫教授指导完成,博士生曾凡伟、马学海与硕士生朱琳为共同第一作者,王鑫教授为通讯作者。Ubiquitin-specific protease (USP) 6 is a hominoid deubiquitinating enzyme previously implicated in intellectual disability and autism spectrum disorder. Although these findings link USP6 to higher brain function, potential roles for USP6 in cognition have not been investigated. Here, we report that USP6 is highly expressed in induced human neurons and that neuron-specific expression of USP6 enhances learning and memory in a transgenic mouse model. Similarly, USP6 expression regulates N-methyl-D-aspartate-type glutamate receptor (NMDAR)-dependent long-term potentiation and long-term depression in USP6 transgenic mouse hippocampi. Proteomic characterization of transgenic USP6 mouse cortex reveals attenuated NMDAR ubiquitination, with concomitant elevation in NMDAR expression, stability, and cell surface distribution with USP6 overexpression. USP6 positively modulates GluN1 expression in transfected cells, and USP6 down-regulation impedes focal GluN1 distribution at postsynaptic densities and impairs synaptic function in neurons derived from human embryonic stem cells. Together, these results indicate that USP6 enhances NMDAR stability to promote synaptic function and cognition.This work was partially supported by the National Natural Science Foundation of China (31871077, 81822014, 81571176 to XW; 81701349 to Hongfeng Z.; 81701130 to QZ; and 81471160 to HS), the National Key R&D Program of China (2016YFC1305900 to XW and HS), the Natural Science Foundation of Fujian Province of China (2017J06021 to XW), the Fundamental Research Funds for the Chinese Central Universities (20720150061 to XW and 20720180040 to ZS), Open Research Fund of State Key Laboratory of Cellular Stress Biology, Xiamen University (SKLCSB2019KF012 to QZ), and China Postdoctoral Science Foundation (2017M612130 to QZ).该研究得到了国家自然科学基金面上项目和优秀青年基金项目的支持

    Calculation for Hard Measured Loads on the Travelling Mechanism of Bridge Inspection Vehicle

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    In allusion to the recently problem of some loads to be calculated and hard measured of travel mechanism of bridge inspection vehicle, based on the principle of superposition in the elastic mechanics, the FEA simulation and test methods have been used to research the hard-measured loads on the travel mechanism of bridge inspection vehicle. The calculation case of the driving force in the driving case and the side load in the turning case of traveling mechanism of bridge inspection vehicle have been solved with this method, the results are used to be applied reference for the property optimization and model selection of mechanical bearing inside of travel mechanism of the bridge inspection vehicle. The research method is of well-reference value for the calculation of the unknown loads of whole machine and parts of construction machinery

    Hydrate dissociation induced by gas diffusion from pore water to drilling fluid in a cold wellbore

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    It is a common view that the high temperature of the drilling fluid can lead to the dissociation of gas hydrate during drilling through hydrate-bearing sediments. This study indicates that the hydrate dissociation in wellbore can also be induced by gas diffusion from pore water to drilling fluid even if the temperature (and the pressure if necessary) of the drilling fluid is well controlled to keep the conditions of hydrate-bearing sediments along the hydrate equilibrium boundary. The dissociation of gas hydrate was modelled based on Fick's first law. It was found that the dissociation rate mainly depended on the temperature of the sediments. The locations of dissociation front of CH4 hydrate and CO2 hydrate in wellbore were calculated as a function of time. The impacts of the hydrate dissociation on the wellbore stability and the resistivity well logging in sediments were evaluated

    Effect of carbon carrier pretreatment on oxygen reduction performance of Co-N/C non-platinum catalyst for fuel cell

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    Cobalt (Co) based oxygen reduction catalysts have become one of the important choices to replace platinum based oxygen reduction catalysts because of their low price, high reserves and easy availability. ECP600 JD was pretreated with nitric acid, mixed with cobalt acetate tetrahydrate, and then pyrolyzed at 800 ℃ in ammonia atmosphere to prepare Co-N/C oxygen reduction catalyst. The infrared spectrum test, alkali neutralization titration and specific surface area measurement show that the number of oxygen-containing functional groups on the surface of ECP600 JD increases, the pore size of ECP600 JD remains unchanged, but the proportion of mesopores increases after nitric acid acidification pretreatment. XRD and TEM tests show that Co5.47N is formed from ECP600 JD and cobalt acetate tetrahydrate after ammonia heat treatment, the Co-N/C catalyst is dispersed evenly without agglomeration. Electrochemical tests show that after pretreatment, the electrocatalytic performance of the prepared Co-N/C catalyst for oxygen reduction reaction (ORR) is better. Under alkaline conditions, the current density reaches 4.2 times that before pretreatment, and belongs to four electron transfer in catalytic kinetics