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Experimental Study on the Performance of ORC System Based on Ultra-Low Temperature Heat Sources

Energy Engineering 2024年第1期121卷 145-168页

作者： Tianyu Zhou Liang Hao Xin xu Meng si Lian Zhang College of Mechanical Engineering Tianjin University of Science&TechnologyTianjin300222China School of Energy Engineering Tianjin Sino-German University of Applied SciencesTianjin300350China Tianjin“The Belt and Road”Joint Laboratory Tianjin Sino-German University of Applied SciencesTianjin300350China

This paper discussed the experimental results of the performance of an organic Rankine cycle(ORC)system with an ultra-low temperature heat *** low boiling point working medium R134a was adopted in the *** simulated heat source temperature(SHST)in this work was set from 39.51°C to 48.60°C by the simulated heat source *** influence of load percentage of simulated heat source(LPSHS)between 50%and 70%,the rotary valve opening(RVO)between 20%and 100%,the resistive load between 36Ωand 180Ωor the no-load of the generator,as well as the autumn and winter ambient temperature on the system performance were *** results showed that the stability of the system was promoted when the generator had a resistive *** power generation(PG)and generator speed(GS)of the system in autumn were better than in winter,but the expander pressure ratio(EPR)was lower than in *** RVO unchanged,the SHST,the mass flow rate(MFR)of the working medium,GS,and the PG of the system increased with the increasing of LPSHS for different generator resistance load *** the RVO was 60%,LPSHS was 70%,the SHST was 44.15°C and the resistive load was 72Ω,the highest PG reached 15.11 ***,a simulation formula was obtained for LPSHS,resistance load,and PG,and its correlation coefficient was between 0.9818 and *** formula can accurately predict the *** experimental results showed that the standard deviation between the experimental and simulated values was below 0.0792,and the relative error was within±5%.

关键词： ORC load percentage of simulated heat source resistive load rotary valve opening power generation

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Variable projection algorithms with sparse constraint for separable nonlinear models

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Control Theory and Technology 2024年第1期22卷 135-146页

作者： Hui-Lang xu Guang-Yong Chen si-Qing Cheng Min Gan Jing Chen College of Computer and Data Science Fuzhou UniversityFuzhou350116FujianChina Fujian Key Laboratory of Network Computing and Intelligent Information Processing Fuzhou UniversityFuzhou350116FujianChina Key Laboratory of Intelligent Metro of Universities in Fujian Fuzhou UniversityFuzhou350116FujianChina Engineering Research Center of Big Data Intelligence Ministry of EducationFuzhou UniversityFuzhou350116FujianChina School of Science Jiangnan UniversityWuxi214122JiangsuChina

Separable nonlinear models are widely used in various fields such as time series analysis, system modeling, and machine learning, due to their flexible structures and ability to capture nonlinear behavior of data. However, identifying the parameters of these models is challenging, especially when sparse models with better interpretability are desired by practitioners. Previous theoretical and practical studies have shown that variable projection (VP) is an efficient method for identifying separable nonlinear models, but these are based on \(L_2\) penalty of model parameters, which cannot be directly extended to deal with sparse constraint. Based on the exploration of the structural characteristics of separable models, this paper proposes gradient-based and trust-region-based variable projection algorithms, which mainly solve two key problems: how to eliminate linear parameters under sparse constraint;and how to deal with the coupling relationship between linear and nonlinear parameters in the model. Finally, numerical experiments on synthetic data and real time series data are conducted to verify the effectiveness of the proposed algorithms.

关键词： Variable projection(VP) Non-smooth constraint Separable nonlinear models

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Superatom-assembled boranes,carboranes,and low-dimensional boron nanomaterials based on aromatic icosahedral B_(12)and C_(2)B_(10)

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Nano Research 2024年第7期17卷 6734-6740页

作者： Qiao-Qiao Yan Yan-Fang wei Qiang Chen Yue-Wen Mu si-Dian Li Institute of Molecular Science Shanxi UniversityTaiyuan 030006China

Using the experimentally known aromatic icosahedral superatoms I_(h)B_(12)H_(12)2−and D_(5d)1,12-C_(2)B_(10)H_(12)as building blocks and based on extensive density functional theory calculations,we predict herein a series of core–shell superpolyhedral boranes and carboranes in a bottom-up approach,including the high-symmetry Th B_(12)@B_(152)H_(72)2−(2),C2h C_(2)B_(10)@B_(152)H_(72)(3),D_(3d)B_(12)@B_(144)H_(66)(4),I_(h)B_(12)@C_(24)B_(12)0H_(72)2−(6),and D_(5d)C_(2)B_(10)@C_(24)B_(12)0H_(72)(7).More interestingly,the superatom-assembled linear D2h B_(36)H_(32)^(2−)(8),close-packed planar D_(3d)B_(84)H_(60)^(2−)(10),and nearly close-packed core−shell D_(3d)B_(12)@B144H_(6)6(4)can be extended periodically to form the one-dimensional(1D)α-rhombohedral borane nanowire B_(12)H_(10)(Pmmm)(9),two-dimensional(2D)α-rhombohedral monolayer borophane B_(12)H_(6)(P m1)(11),and the experimentally known three-dimensional(3D)α-rhombohedral boron(R m)(12)which can be viewed as an assembly of the monolayer B_(12)H_(6)(11)staggered in vertical direction,setting up a bottom-up strategy to form low-dimensional boron-based nanomaterials from their borane“seeds”via partial or complete *** bonding analyses indicate that the high stability of these nanostructures originates from the spherical aromaticity of their icosahedral B_(12)or C_(2)B_(10)structural units which possess the universal skeleton electronic configuration of 1S21P61D101F8 following the Wade’s n+1 *** infrared(IR)and Raman spectra of the most-concerned neutral B_(12)@B144H_(6)6(4)and C_(2)B_(10)@C_(24)B_(12)0H_(72)(7)are computationally simulated to facilitate their experimental characterizations.

关键词： superatom-assembling bottom-up approach density functional theory superpolyhedral boranes superpolyhedral carboranes borophanes

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Observations on Durability of a Pyrolytic Carbon Bileaflet Mechanical Heart Valve

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Chinese Journal of Biomedical Engineering(English Edition) 2010年第3期19卷 109-113页

作者： LOU Hai-fang CHEN Ru-kun xu si-wei DONG Ai-qiang The 2nd Affiliated Hospital of Medical College of Zhejiang University Hangzhou 310009 China

This study aims to observe the durability of a pyrolytic carbon bileaflet mechanical valve prosthesis. The mechanical valves prosthesis was tested in vitro by the durability test instrument of valve prosthesis. Then in vivo, the durability of the implanted valves was observed with animal experiments and elinieal application. In the impact test for 5 min and durability test of 380 million eyeles in vitro, there was no the phenomenon of flyer, perforation and fracture observed, as well as no wear or pit found on the surface of valve leaflets. The valve leaflets could normally be turned on or off. The weight of the valve was（1.0031 ± 0.0004） g for 23 mm and（1.6003 ± 0.0002） g for 27 mm. The hydrodynamies test demonstrated that the valve prosthesis had still exeellent hemodynamic performance after the durability test. The animal autopsy showed that the valve leaflets could normally be turned on or off, and no wear was found. By follow-up of 62 patients implanted the valves, all patients had long-terms survival, no complication caused by valve was found. The age of the longest survival was more than 10 years. This study demonstrates that the new meehanieal valve prosthesis have excellent durable performance.

关键词： mechanical heart valve pyrolytic carbon durability hemodynamics

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Clinical observation on warm needling moxibustion for erectile dysfunction

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Journal of Acupuncture and Tuina Science 2017年第1期15卷 59-62页

作者： Liu Peng Liu Su-jun xu si-wei Yang Yang Shou Yin Zhang Kai-yong Jiang Hui-ru Zhang Bi-meng Shanghai University of Traditional Chinese Medicine Shanghai 201203 China Shanghai First People＇s Hospital Shanghai Jiao Tong University School of Medicine Shanghai 200080 China

Objective： To observe the therapeutic effect of warm needling moxibustion for erectile dysfunction （ED）. Methods： A total of 46 eligible ED patients were randomized into a treatment group （n=24） and a control group （n=22）. The treatment group was intervened by warm needling moxibustion while the control group by conventional acupuncture treatment, for a total of 4 courses. The therapeutic effect was evaluated by the international index of erectile function 5 （IIEF-5）. Results： After 4 courses of treatment, the overall effective rate was 91.3% in the treatment group （23 completed）, versus 75.0% in the control group （20 completed）, with a significant difference （P〈0.05）. After the treatment, the change of IIEF-5 score in the treatment group was significantly different from that in the control group （P〈0.05）. Conclusion： Warm needling moxibustion can produce a more significant efficacy than conventional acupuncture in the treatment of ED.

关键词： Acupuncture Therapy Moxibustion Therapy Acupuncture-moxibustion Therapy Warm Needling Therapy Erectile Dvsfunction: Male

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Crystal facet-dependent CO_(2) cycloaddition to epoxides over ZnO catalysts

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Frontiers of Chemical Science and Engineering 2024年第5期18卷 49-59页

作者： Yongjian wei Ying Li Yunfei xu Yinghui Sun Tong xu Haiou Liang Jie Bai Inner Mongolia Key Laboratory of Industrial Catalysis Hohhot 010051China College of Chemical Engineering Inner Mongolia University of TechnologyHohhot 010051China

With regard to green chemistry and sustainable development,the fixation of CO_(2) into epoxides to form cyclic carbonates is an attractive and promising pathway for CO_(2) *** oxides,renowned as promising eco-friendly catalysts for industrial production,are often undervalued in terms of their impact on the CO_(2)addition *** this work,we successfully developed ZnO nanoplates with(002)surfaces and ZnO nanorods with(100)surfaces via morphology-oriented regulation to explore the effect of crystal faces on CO_(2) *** quantitative data obtained from electron paramagnetic resonance spectroscopy indicated that the concentration of oxygen vacancies on the ZnO nanoplate surfaces was more than twice that on the ZnO nanorod *** functional theory calculations suggested that the(002)surfaces have lower adsorption energies for CO_(2) and epichlorohydrin than the(100)*** a result,the yield of cyclochloropropene carbonate on the ZnO nanoplates(64.7%)was much greater than that on the ZnO nanorods(42.3%).Further evaluation of the reused catalysts revealed that the decrease in the oxygen vacancy concentration was the primary factor contributing to the decrease in catalytic *** on these findings,a possible catalytic mechanism for CO_(2) cycloaddition with epichlorohydrin was *** work provides a new idea for the controllable preparation of high-performance ZnO catalysts for the synthesis of cyclic carbonates from CO_(2) and epoxides.

关键词： carbon dioxide cycloaddition zinc oxide crystal face oxygen vacancy

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Optical coherence tomography angiography metrics in different stages of diabetic macular edema

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Eye and Vision 2024年第3期10卷 13-20页

作者： Ruyi Han Ruowen Gong wei Liu Gezhi xu Eye Institute and Department of Ophthalmology Eye and ENT Hospital of Fudan University83 Fenyang RoadShanghai200031People’s Republic of China Key Laboratory of Visual Impairment and Restoration Fudan UniversityShanghaiPeople’s Republic of China Key Laboratory of Myopia(Fudan University) Chinese Academy of Medical SciencesNational Health CommissionShanghaiPeople’s Republic of China

Background To investigate the optical coherence tomography angiography(OCTA)characteristics of diabetic macular edema(DME)at different *** This study was a cross-sectional *** diagnosed with DME were *** was classified into early,advanced,and severe *** vessel density(VD)in the superficial vascular plexus(SVP),deep vascular plexus(DVP)and foveal avascular zone(FAZ)parameters,including FAZ area,FAZ perimeter,acircularity index and foveal VD in a 300-μm-wide region around the FAZ(FD-300),were calculated by the AngioVue software.A multivariate generalized estimating equation was used to evaluate the associations between visual acuity and OCTA *** Ninety-two eyes from 74 patients with DME were included in this *** to early(P=0.006)and advanced DME(P=0.003),the acircularity index was higher in severe *** whole and parafoveal VD in the DVP decreased in eyes with severe DME compared to early DME(P=0.018,P=0.005,respectively)and advanced DME(P=0.035,P=0.012,respectively).In the multivariate generalized estimating equation,DME severity,FAZ area and foveal thickness were positively associated with worse visual acuity(P=0.001,P=0.007 and P=0.001,respectively).Conclusion Compared to early and advanced DME,severe DME showed increased irregularity in the FAZ and more extensive vessel damage in the *** severity level of DME,larger FAZ area,and increased foveal thickness could be risk factors for poor visual *** registration The protocol was published in the Chinese Clinical Trial Registry(ChiCTR2000033082).

关键词： Optical coherence tomography angiography Diabetic macular edema Vessel density Acircularity index

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Does Green Food Certification promote agri-food export quality?Evidence from China

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Journal of Integrative Agriculture 2024年第3期23卷 1061-1074页

作者： Ping wei Hongman Liu Chaokai xu Shibin Wen College of Economics and Management China Agricultural UniversityBeijing 100083China School of Public Affairs Zhejiang UniversityHangzhou 310058China

The construction of a food certification system plays a vital role in upgrading export quality, which previous studies have largely overlooked. We match China's industry-level data of Green Food Certification with its HS6-digit export data of agri-food products to quantify the impact of Green Food Certification on export quality. We identify the significant and positive effect of Green Food Certification on export quality. The 2SLS estimation based on instrumental variables and a range of robustness checks confirm the validity and robustness of the benchmark conclusions. Further analysis discloses that Green Food Certification improves export quality by raising agricultural production efficiency and brand premiums. Heterogeneity analysis shows that the effect of Green Food Certification varies across regions, notably improving the quality of agri-food products exported to developed regions and regions with high levels of import supervision. Furthermore, among various product types, Green Food Certification significantly improves the export quality of primary products and products vulnerable to non-tariff measures. The above findings could guide the future development of agri-food quality certification systems, potentially leading to a transformation and promotion of the agri-food trade.

关键词： Green Food Certification agri-food products green transformation export quality food labeling

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A novel dandelion-based bionic proppant and its transportation mechanism in different types of fractures

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Petroleum Science 2024年第4期21卷 2583-2599页

作者： Jun Li Ming-Yi Wu xu Han si-Yuan He Ze-Yu Lin State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum University sichuan Particles Energy and Technology Co. Ltd Chongqing Industry Polytechnic College Petroleum Systems Engineering Faculty of Engineering and Applied Science University of Regina

Low-permeability reservoirs are generally characterized by low porosity and low permeability. Obtaining high production using the traditional method is technologically challenging because it yields a low reservoir recovery factor. In recent years, hydraulic fracturing technology is widely applied for efficiently exploiting and developing low-permeability reservoirs using a low-viscosity fluid as a fracturing ***, the transportation of the proppant is inefficient in the low-viscosity fluid, and the proppant has a low piling-up height in fracture channels. These key challenges restrict the fluid(natural gas or oil) flow in fracture channels and their functional flow areas, reducing the profits of hydrocarbon *** study aimed to explore and develop a novel dandelion-bionic proppant by modifying the surface of the proppant and the fiber. Its structure was similar to that of dandelion seeds, and it had high transport and stacking efficiency in low-viscosity liquids compared with the traditional ***, the transportation efficiency of this newly developed proppant was investigated experimentally using six different types of fracture models(tortuous fracture model, rough fracture model,narrow fracture model, complex fracture model, large-scale single fracture model, and small-scale single fracture model). Experimental results indicated that, compared with the traditional proppant, the transportation efficiency and the packing area of the dandelion-based bionic proppant significantly improved in tap water or low-viscosity fluid. Compared with the traditional proppant, the dandelionbased bionic proppant had 0.1-4 times longer transportation length, 0.3-5 times higher piling-up height, and 2-10 times larger placement area. The newly developed proppant also had some other extraordinary features. The tortuosity of the fracture did not influence the transportation of the novel proppant. This proppant could easily enter the branch fracture and n

关键词： Dandelion-based bionic proppant Low-viscosity fracturing fluid Unconventional reservoir Volumetric fracturing stimulation

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Colloid-facilitated release of polybrominated diphenyl ethers at an e-waste recycling site: evidence from undisturbed soil core leaching experiments

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Frontiers of Environmental Science & Engineering 2024年第2期18卷 91-101页

作者： Zebin Huo Mengjun Xi Lianrui xu Chuanjia Jiang wei Chen College of Environmental Science and Engineering Ministry of Education Key Laboratory of Pollution Processes and Environmental CriteriaTianjin Key Laboratory of Environmental Remediation and Pollution ControlNankai UniversityTianjin 300350China

Polybrominated diphenyl ethers (PBDEs), a class of persistent organic pollutants, have been frequently detected in soil at e-waste recycling sites. However, the key factors controlling the transport of PBDEs from surface soil to the vadose zone and groundwater are unclear. Here, colloid-enhanced leaching of PBDEs from undisturbed soil cores collected at an e-waste recycling site in Tianjin, China, is reported. Spatially heterogeneous release of colloids and PBDEs was observed in all the tested soil cores under chemical and hydrodynamic perturbations, indicating the presence of preferential flow paths. Colloid concentration in the effluent significantly increased as ionic strength decreased (from 10 to 0.01 mmol/L), probably due to the stronger electrostatic repulsion between colloidal particles and the soil matrix at lower ionic strength. In contrast, colloid mobilization was not significantly affected by the changes in pH of the influent (from 4.0 to 10.0) and flow rate (from a Darcy velocity of 1.5 to 6.0 cm/h). The concentrations of 2,2′,3,3′,4,4′,5,5′,6,6′-decabromodiphenyl ether (BDE-209), the predominant PBDE congener at the site, detected in the leachate (ranging from 1.09 to 3.43 ng/L) were much lower than previously reported results from packed column leaching tests, and were positively correlated with colloid concentrations. This indicates that remobilization of colloids at e-waste recycling sites can promote the leaching and downward migration of PBDEs from surface soil. The findings highlight the potential risk of surface soil PBDE contamination to groundwater quality and call for further understanding of colloid-facilitated transport for predicting the fate of PBDEs at e-waste recycling sites.

关键词： Polybrominated diphenyl ether Colloid-facilitated transport E-waste recycling site Undisturbed soil core Groundwater quality

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