期刊文献+
共找到493篇文章
< 1 2 25 >
每页显示 20 50 100
Comparative Study on the Phenolic Compound Extraction in the Biorefinery Upgrading Process of Multi-Feedstock Biomass Waste Based Bio-Oil
1
作者 Haniif Prasetiawan Dewi Selvia Fardhyanti +1 位作者 Hadiyanto Widya Fatriasari 《Journal of Renewable Materials》 2025年第7期1347-1366,共20页
Bio-oil is a renewable fuel that can be obtained from biomass waste,such as empty palm fruit bunches,sugarcane bagasse,and rice husks.Within a biorefinery framework,bio-oil had not met the standards as a fuel due to t... Bio-oil is a renewable fuel that can be obtained from biomass waste,such as empty palm fruit bunches,sugarcane bagasse,and rice husks.Within a biorefinery framework,bio-oil had not met the standards as a fuel due to the presence of impurities like corrosive phenol.Therefore,the separation of phenol from bio-oil is essential and can be achieved using the extraction method.In this study,biomass wastes(empty fruit bunches of oil palm,sugarcane bagasse,and rice husk)were pyrolyzed in a biorefinery framework to produce bio-oil,which was then refined through liquid-liquid extraction with a methanol-chloroform and ethyl acetate solvents to remove its phenolic compound.The extraction with methanol-chloroform solvent was carried out for 1 h at 50℃.Meanwhile,extraction with ethyl acetate solvent was carried out for 3 h at 70℃.Both extractions used the same variations,i.e.,bio-oil:solvent ratio at 1:1,1:2,1:3,and 1:4,and stirring speeds of 150 rpm,200 rpm,250 rpm,and 300 rpm.The bio-oil obtained from this study contained complex chemical compounds and had characteristics such as a pH of 5,a density of 1.116 g/mL,and a viscosity of 29.57 cSt.Theoptimization results using response surface methodology(RSM)showed that the best yield formethanolchloroform was 72.98%at a stirring speed of 250 rpm and a ratio of 1:3.As for ethyl acetate solvent,the highest yield obtained was 71.78%at a stirring speed of 237.145 rpm and a ratio of 1:2. 展开更多
关键词 BIO-OIL liquid-liquid extraction PHENOL methanol-chloroform ethyl acetate
在线阅读 下载PDF
Pharmacokinetics and Safety of Chiglitazar in Patients with Renal Impairment: A Multicenter, Open-label, Parallel-controlled Phase I Clinical Trial
2
作者 Jinjie Yuan Jia Yu +9 位作者 Jiwen Sun Huan Wang Guoyuan Lu Wengang Sha Xiaodong Yang Haixiang Cao Yu Chen Desi Pan Xinhao Wang Hua Zhang 《Journal of Clinical and Nursing Research》 2025年第5期252-263,共12页
Background:Chiglitazar is a novel pan-agonist that can activate all three subtypes of peroxisome proliferator-activated receptor.It was approved for the treatment of type 2 diabetes mellitus as monotherapy on October ... Background:Chiglitazar is a novel pan-agonist that can activate all three subtypes of peroxisome proliferator-activated receptor.It was approved for the treatment of type 2 diabetes mellitus as monotherapy on October 19,2021,and as combination therapy with metformin when using metformin alone failed in blood glucose control on July 16,2024,by the National Medical Products Administration(NMPA)in China.However,pharmacokinetic(PK)study of this product in patients with renal impairment have not yet been conducted.The purpose of this study is to evaluate the effects of renal impairment on the PK and safety after a single oral dose of Chiglitazar.Methods:This multicenter,open-label,parallel-controlled,single-dose Phase I clinical trial(NCT 05515458)enrolled 24 participants(12/group)with severe renal impairment(SRI)or normal renal function(NRF).All participants received a single oral dose of 48 mg chiglitazar after breakfast and the PK and safety was evaluated.Results:The median Tmax was similar in both SRI and NRF groups(5.01 vs.5.02 hours).The geometric mean ratios(GMR)for Cmax,AUC0-t,and AUC0-∞were 0.807(90%confidence interval[CI]:0.697–0.935),0.853(90%CI:0.713–1.02),and 0.855(90%CI:0.716–1.02),respectively,indicating that SRI did not significantly affect the exposure of chiglitazar.The Cmax was weakly positively correlated with eGFR(r=0.4798,P=0.0177)and creatinine clearance rate(r=0.4667,P=0.0215).Urinary excretion of chiglitazar was negligible in the SRI group,with average values of Ae0-t=2,900 ng,Fe0-t=0.0060%,and CLR=0.323 mL/h within 0–72 hours post-dose.The treatment-emergent adverse event(TEAE)incidence in the SRI group(16.7%,2/12)was comparable to that in the NRF group(25%,3/12).All TEAEs were of mild severity and were adjudicated by the investigators to be unrelated to chiglitazar.No serious AE were reported.Chiglitazar exhibits a favorable safety profile.Conclusion:Severe renal impairment does not significantly affect the PK and safety of chiglitazar,and no dose adjustment for mild,moderate,and severe renal impairments is required. 展开更多
关键词 Chiglitazar PHARMACOKINETICS Renal impairment SAFETY
暂未订购
Rate-distortion optimized frame dropping and scheduling for multi-user conversational and streaming video 被引量:1
3
作者 CHAKARESKI Jacob STEINBACH Eckehard 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2006年第5期864-872,共9页
We propose a Rate-Distortion (RD) optimized strategy for frame-dropping and scheduling of multi-user conversa- tional and streaming videos. We consider a scenario where conversational and streaming videos share the fo... We propose a Rate-Distortion (RD) optimized strategy for frame-dropping and scheduling of multi-user conversa- tional and streaming videos. We consider a scenario where conversational and streaming videos share the forwarding resources at a network node. Two buffers are setup on the node to temporarily store the packets for these two types of video applications. For streaming video, a big buffer is used as the associated delay constraint of the application is moderate and a very small buffer is used for conversational video to ensure that the forwarding delay of every packet is limited. A scheduler is located behind these two buffers that dynamically assigns transmission slots on the outgoing link to the two buffers. Rate-distortion side information is used to perform RD-optimized frame dropping in case of node overload. Sharing the data rate on the outgoing link between the con- versational and the streaming videos is done either based on the fullness of the two associated buffers or on the mean incoming rates of the respective videos. Simulation results showed that our proposed RD-optimized frame dropping and scheduling ap- proach provides significant improvements in performance over the popular priority-based random dropping (PRD) technique. 展开更多
关键词 RATE-DISTORTION optimization VIDEO FRAME dropping CONVERSATIONAL video Streaming video Distortion matrix Hinttracks Scheduling Resource assignment
在线阅读 下载PDF
Eco-geological environment quality assessment based on multi-source data of the mining city in red soil hilly region, China 被引量:4
4
作者 ZHAO Fei-fei HE Man-chao +2 位作者 WANG Yun-tao TAO Zhi-gang LI Chun 《Journal of Mountain Science》 SCIE CSCD 2022年第1期253-275,共23页
High-intensity and large-scale resource development seriously threatens the fragile ecological environment in the red soil hilly region in southern China. This paper analyzes the eco-geological environmental problems ... High-intensity and large-scale resource development seriously threatens the fragile ecological environment in the red soil hilly region in southern China. This paper analyzes the eco-geological environmental problems and factors affecting Ganzhou, a mining city in the red soil hilly region,based on field survey and literature. The ecogeological environment quality(EGEQ) assessment system, which covered 11 indicators in physical geography, mining development, geological hazards,as well as water and soil pollution, was established through multi-source data utilization such as remote sensing images, DEM(Digital Elevation Model), field survey and on-site monitoring data. The comprehensive weight of each indicator was calculated through the Analytic Hierarchy Process(AHP) and entropy method. The eco-geological environment assessment map was developed by calculating the EGEQ value through the linear weighted method. The assessment results show that the EGEQ was classified into I-V grades from excellent to worse, among which, EGEQ of I-II accounted for 29.88%, EGEQ of III accounted for 32.35% and EGEQ of IV-V accounted for 37.77%;the overall EGEQ of Ganzhou was moderate. The assessment system utilized in this research provides scientific and accurate results, which in turn enable the proposal of some tangible protection suggestions. 展开更多
关键词 Eco-geological environment assessment Mining city Red soil hilly region AHP Entropy method
原文传递
Markov Model of Multi-Class, Multi-Server Queuing System with Priorities
5
作者 Mindaugas Snipas Eimutis Valakevicius 《通讯和计算机(中英文版)》 2010年第1期1-3,共3页
关键词 排队系统 多服务器 马尔可夫模型 多级 服务时间 性能特点 指数分布 到达过程
在线阅读 下载PDF
Realization of Unbiased Ferrite Cobalt Nano-Composite for Non-Reciprocal Microwave Components
6
作者 Ardaches Tchangoulian Elie Abou Diwan +5 位作者 Didier Vincent Sophie Neveu Francois Royer Jean Pierre Chatelon Chadi Nader Roland Habchy 《材料科学与工程(中英文A版)》 2013年第11期751-756,共6页
关键词 纳米复合材料 微波器件 钴铁氧体 钴纳米粒子 法拉第旋转 互惠 无偏 多孔氧化铝膜
在线阅读 下载PDF
Multi-wavelength fibril dynamics and oscillations above sunspot– I. morphological signature
7
作者 Emanuel Sungging Mumpuni Dhani Herdiwijaya +1 位作者 Mitra Djamal Thomas Djamaluddin 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第11期1843-1856,共14页
In this work we selected one particular fibril from a high resolution observation of the solar chromosphere with the Dutch Open Telescope, and tried to obtain a broad picture of the intricate mechanism that might be o... In this work we selected one particular fibril from a high resolution observation of the solar chromosphere with the Dutch Open Telescope, and tried to obtain a broad picture of the intricate mechanism that might be operating in the multiple layers of the solar atmosphere visible in high cadence multi-wavelength observations. We analyzed the changing fibril pattern using multi-wavelength tomography, which consists of both the Hα line center and the blue wing, Doppler signal, Ca II H, and the G-band. We have found that the intermittent ejected material through the fibril from Doppler images has clearly shown an oscillation mode, as seen in the Hα blue wing.The oscillations in the umbrae and penumbrae magnetic field lines that are above the sunspot cause a broadening and the area forms a ring shape from 3 to 15 minute oscillations as a function of height. These made a distinct boundary between the umbrae and penumbrae which suggests a comb structure, and indicates that the oscillations could propagate along the inclined magnetic flux tubes from below. The 3 minute oscillations strongly appeared in the broadly inclined penumbrae magnetic field lines and showed a clear light bridge. The well known 5 minute oscillations were dominant in the umbrae-penumbrae region boundary. The long 7 minute oscillations were transparent in the Hα blue wing, as well as the 10 and 15 minute oscillations. They were concentrated in the inner-penumbrae, as seen in the Hα line center. From these findings we propose that the fibril acts as a fabric for interaction between the layers,as well as related activities around the active region under investigation. 展开更多
关键词 minute morphological signature picture propagate fabric Figure sector visible concentrated
在线阅读 下载PDF
Role of water chemistry on estrone removal by nanofiltration with the presence of hydrophobic acids 被引量:1
8
作者 Xue JIN Jiangyong HU 《Frontiers of Environmental Science & Engineering》 SCIE EI CAS CSCD 2015年第1期164-170,共7页
Hydrophobic acid organic matter (HpoA) extracted from treated effluent has been known to improve the rejection of steroid hormone estrone by reverse osmosis (RO) and nanofiltration (NF) membranes. In this study,... Hydrophobic acid organic matter (HpoA) extracted from treated effluent has been known to improve the rejection of steroid hormone estrone by reverse osmosis (RO) and nanofiltration (NF) membranes. In this study, the effects of solution chemistry (solution pH and ionic strength) on the estrone rejection by NF membrane with the presence of HpoA were systematically investigated. Crossflow nanofiltration experiments show that the presence of HpoA significantly improved estrone rejection at all pH and ionic strength levels investigated. It is consistently shown that the "enhancement effect" of HpoA on estrone rejection at neutral and alkaline pH is attributed to the binding of estrone by HpoA macromolecules via hydrogen bonding between phenolic functional groups in feed solutions, which leads to an increase in molecular weight and appearance of negative charge. The membrane exhibited the best performance in terms ofestrone rejection at pH 10.4 (compared to pH 4 and pH 7) as a result of strengthening the electrostatic repulsion between estrone and membrane with the presence of HpoA. At neutral pH level, the ability of HpoA macromolecules to promote estrone rejection became stronger with increasing ionic strength due to their more extended conformation, which created more chances for the association between estrone and HpoA. The important conclusion of this study is that increasing solution pH and salinity can greatly intensify the "enhancement effect" of HpoA. These results can be important for NF application in direct/indirect potable water reuse. 展开更多
关键词 steroid hormone nanofiltration(NF) REJECTION water chemistry hydrophobic acids indirect potable water reuse
原文传递
Direct fiber vector eigenmode multiplexing transmission seeded by integrated optical vortex emitters 被引量:5
9
作者 Jun Liu Shi-Mao Li +9 位作者 Long Zhu An-Dong Wang Shi Chen Charalambos Klitis Cheng Du Qi Mo Marc Sorel Si-Yuan Yu Xin-Lun Cai Jian Wang 《Light: Science & Applications》 SCIE EI CAS CSCD 2017年第1期175-180,共6页
Spatial modes have received substantial attention over the last decades and are used in optical communication applications.In fiber-optic communications,the employed linearly polarized modes and phase vortex modes car... Spatial modes have received substantial attention over the last decades and are used in optical communication applications.In fiber-optic communications,the employed linearly polarized modes and phase vortex modes carrying orbital angular momentum can be synthesized by fiber vector eigenmodes.To improve the transmission capacity and miniaturize the communication system,straightforward fiber vector eigenmode multiplexing and generation of fiber-eigenmode-like polarization vortices(vector vortex modes)using photonic integrated devices are of substantial interest.Here,we propose and demonstrate direct fiber vector eigenmode multiplexing transmission seeded by integrated optical vortex emitters.By exploiting vector vortex modes(radially and azimuthally polarized beams)generated from silicon microring resonators etched with angular gratings,we report data-carrying fiber vector eigenmode multiplexing transmission through a 2-km large-core fiber,showing low-level mode crosstalk and favorable link performance.These demonstrations may open up added capacity scaling opportunities by directly accessing multiple vector eigenmodes in the fiber and provide compact solutions to replace bulky diffractive optical elements for generating various optical vector beams. 展开更多
关键词 fiber-optic communications fiber vector eigenmode MULTIPLEXING optical vortex photonic integrated devices
原文传递
DIFFUSIVE LIMITS OF THE BOLTZMANN EQUATION IN BOUNDED DOMAIN
10
作者 Raffaele Esposito Yan Guo +1 位作者 Chanwoo Kim Rossana Marra 《Annals of Applied Mathematics》 2020年第2期111-185,共75页
The goal of this paper is to study the important diffusive expansion via an alternative mathematical approach other than that in [21].
关键词 steady and unsteady Boltzmann equation hydrodynamics limits boundary effects
原文传递
Branched hybridization chain reaction-using highly dimensional DNA nanostructures for label-free,reagent-less,multiplexed molecular diagnostics
11
作者 Gaolian Xu Mingliang Lai +3 位作者 Rab Wilson Andrew Glidle Julien Reboud Jonathan M.Cooper 《Microsystems & Nanoengineering》 EI CSCD 2019年第1期316-322,共7页
The specific and multiplexed detection of DNA underpins many analytical methods,including the detection of microorganisms that are important in the medical,veterinary,and environmental sciences.To achieve such measure... The specific and multiplexed detection of DNA underpins many analytical methods,including the detection of microorganisms that are important in the medical,veterinary,and environmental sciences.To achieve such measurements generally requires enzyme-mediated amplification of the low concentrations of the target nucleic acid sequences present,together with the precise control of temperature,as well as the use of enzyme-compatible reagents.This inevitably leads to compromises between analytical performance and the complexity of the assay.The hybridization chain reaction(HCR)provides an attractive alternative,as a route to enzyme-free DNA amplification.To date,the linear nucleic acid products,produced during amplification,have not enabled the development of efficient multiplexing strategies,nor the use of label-free analysis.Here,we show that by designing new DNA nanoconstructs,we are able,for the first time,to increase the molecular dimensionality of HCR products,creating highly branched amplification products,which can be readily detected on label-free sensors.To show that this new,branching HCR system offers a route for enzyme-free,label-free DNA detection,we demonstrate the multiplexed detection of a target sequence(as the initiator)in whole blood.In the future,this technology will enable rapid point-of-care multiplexed clinical analysis or in-the-field environmental monitoring. 展开更多
关键词 REAGENT ATTRACTIVE branching
原文传递
Ion compaction effect in hollow FePt nanochains with ultrathin shell under low energy ion irradiation
12
作者 Jialong Liu Jianguo Wu +6 位作者 Long Cheng Suyun Niu Zhiqiang Wang Mengyuan Zhu Jingyan Zhang Shouguo Wang Wei Wang 《Nano Research》 SCIE EI CSCD 2022年第10期9309-9318,共10页
The morphology manipulation of nanomaterials by ion irradiation builds a way to precisely control physicochemical properties.Under the continuous irradiation of low energy Ga+,Ne+,and He+ions,an ion compaction effect ... The morphology manipulation of nanomaterials by ion irradiation builds a way to precisely control physicochemical properties.Under the continuous irradiation of low energy Ga+,Ne+,and He+ions,an ion compaction effect has been found in hollow FePt nanochains with ultrathin shell that the volumes of the nanochains are gradually compacted by ions.The deep learning algorithm has been successfully applied to automatically and precisely measure average sizes of spheres in hollow FePt nanochains.The compaction under ion irradiation is very fast in the very early period and then proceeds to a slow region.The compaction rates in both regions are linearly fitted and all the values are in the order of 10^(–17) to 10^(–14) cm^(2)/ion.Ion species and ion current have effect on the compaction rate.For example,the compaction rate of Ga+ions is larger than those of Ne+and He+ions under an identical current,while irradiation with larger current can compact nanochains faster.The ion compaction effect originates from the local shear deformation caused by the interaction between incident ions and the electrons of Fe and Pt atoms in the ultrathin shell.With continuous irradiation,the crystalline clusters of FePt nanchains firstly grow larger and then become amorphous.The ion compaction effect can be applied to tune the size and crystal structure of hollow structures with a precise rate by choosing appropriate ion species and current. 展开更多
关键词 ion compaction effect hollow structure ion irradiation FEPT
原文传递
醇解度和纺丝液含量对聚乙烯醇静电纺纳米纤维隔膜性能的影响 被引量:1
13
作者 毕谷帅 张锦中 +1 位作者 唐晓峰 查刘生 《化工新型材料》 北大核心 2025年第3期141-145,共5页
以聚乙烯醇(PVA)为成纤聚合物,以水为溶剂,通过静电纺丝技术制备了锂离子电池用纳米纤维隔膜,研究了PVA醇解度和纺丝液含量对隔膜孔隙率、吸液率、热尺寸稳定性、力学性能和电化学性能的影响。结果表明:在纺丝液含量相同的条件下,PVA的... 以聚乙烯醇(PVA)为成纤聚合物,以水为溶剂,通过静电纺丝技术制备了锂离子电池用纳米纤维隔膜,研究了PVA醇解度和纺丝液含量对隔膜孔隙率、吸液率、热尺寸稳定性、力学性能和电化学性能的影响。结果表明:在纺丝液含量相同的条件下,PVA的醇解度越高,隔膜的孔隙率、吸液率、抗拉强度、热尺寸稳定性和离子电导率呈逐渐增大的趋势;在PVA醇解度相同的条件下,随着纺丝液含量的增加,隔膜的孔隙率和离子电导率逐渐升高,抗拉强度呈下降趋势;PVA的醇解度和纺丝液含量对隔膜的电化学稳定性影响很小。 展开更多
关键词 锂离子电池 纳米纤维隔膜 聚乙烯醇 静电纺丝 醇解度 纺丝液含量
原文传递
从MTPE到HACT:大语言模型驱动的翻译流程创新研究 被引量:2
14
作者 刘世界 张滟 《外语教育研究》 2025年第1期18-26,共9页
大语言模型(LLMs)在翻译领域的广泛应用正推动机器翻译译后编辑(MTPE)流程的技术性变革。文章通过系统考察译前编辑、MTPE、自动译后编辑及“人工智能+译后编辑”的理论内涵与技术发展轨迹,结合当前LLMs在翻译领域中的实践应用,提出并... 大语言模型(LLMs)在翻译领域的广泛应用正推动机器翻译译后编辑(MTPE)流程的技术性变革。文章通过系统考察译前编辑、MTPE、自动译后编辑及“人工智能+译后编辑”的理论内涵与技术发展轨迹,结合当前LLMs在翻译领域中的实践应用,提出并明确界定了人智协同翻译(HACT)的概念内涵与核心特征。研究深入探讨了LLMs在HACT流程中的应用场景与实现策略,分析了HACT对译者角色定位、翻译项目管理、行业质量管理体系等维度的影响,并从技术研发、人才培养和行业协会三个层面提出了推动HACT在语言服务行业中应用的对策和建议。旨在为智能技术赋能场景下的翻译流程创新与变革提供理论依据和实践路径。 展开更多
关键词 大语言模型(LLMs) 翻译流程 翻译实践 机器翻译译后编辑(MTPE) 人智协同翻译(HACT)
在线阅读 下载PDF
数字普惠金融、高管财务背景与企业财务风险 被引量:2
15
作者 曾婉晴 杨永忠 《财会通讯》 北大核心 2025年第8期39-42,56,共5页
文章选取2013—2022年我国沪深A股上市公司为研究对象,从企业财务风险角度出发,深入考察数字普惠金融对企业财务风险的影响,并进一步探究数字普惠金融与高管财务背景的相互作用关系。研究发现,数字普惠金融能够显著降低企业的财务风险,... 文章选取2013—2022年我国沪深A股上市公司为研究对象,从企业财务风险角度出发,深入考察数字普惠金融对企业财务风险的影响,并进一步探究数字普惠金融与高管财务背景的相互作用关系。研究发现,数字普惠金融能够显著降低企业的财务风险,结合高管财务背景分析发现,数字普惠金融与高管财务背景存在替代作用,即高管财务背景会削弱数字普惠金融对企业财务风险的抑制作用。最后,结合行业竞争程度差异进行分析,相比于行业竞争程度低,在行业竞争程度高时,数字普惠金融对企业财务风险的抑制作用更显著。 展开更多
关键词 数字普惠金融 高管财务背景 企业财务风险 行业竞争程度
在线阅读 下载PDF
桑白皮中异戊烯基黄酮抗痤疮丙酸杆菌活性及其作用机制
16
作者 彭华勇 武子琦 +3 位作者 王建超 黄宏辉 徐新军 杨得坡 《林产化学与工业》 北大核心 2025年第6期115-123,共9页
为研究桑白皮中异戊烯基黄酮化合物对痤疮丙酸杆菌(Cutibacterium acnes)的抗菌活性及其作用机制,通过体外抗菌活性测定确认桑辛素的抗菌活性最佳,其最低抑菌质量浓度(MIC)为1.2 mg/L。利用扫描电子显微镜、一体化细胞成像及流式细胞术... 为研究桑白皮中异戊烯基黄酮化合物对痤疮丙酸杆菌(Cutibacterium acnes)的抗菌活性及其作用机制,通过体外抗菌活性测定确认桑辛素的抗菌活性最佳,其最低抑菌质量浓度(MIC)为1.2 mg/L。利用扫描电子显微镜、一体化细胞成像及流式细胞术、Nano LC-ESI MS/MS等技术,以及细胞生物学实验分析桑辛素对C.acnes的抗菌表型与潜在的作用机制。研究结果表明:桑辛素能够破坏C.acnes的细胞膜结构,导致大分子蛋白质、DNA和RNA泄露,在1.2 mg/L桑辛素处理时,泄漏量分别为50.9、148.4和97.1 mg/L。桑辛素处理使C.acnes质膜蛋白的表达上调,能量代谢相关的脱氢酶下调,影响氧化还原稳态及三磷酸腺苷(ATP)生成,从而介导细菌死亡。桑辛素处理抑制了C.acnes感染人永生化角质形成细胞(HaCaT)的能力。 展开更多
关键词 桑白皮 桑辛素 痤疮丙酸杆菌 皮肤感染 烟酰胺腺嘌呤二核苷酸 氧化还原
在线阅读 下载PDF
车辆荷载作用下大位移梳齿板式伸缩缝动力特性分析
17
作者 付晓瑗 郝向炜 +1 位作者 秦培雷 邵兴伟 《贵州大学学报(自然科学版)》 2025年第6期115-124,共10页
为了研究伸缩缝在车辆平稳过桥条件下的动力性能,本文以某多跨连续刚构桥梳齿板式伸缩缝为研究对象,采用ANSYS建立梳齿板式伸缩缝有限元模型,选用单车荷载模型,研究不同车速车辆荷载作用下的动力特性,同时研究不同超重比例和螺栓预紧力... 为了研究伸缩缝在车辆平稳过桥条件下的动力性能,本文以某多跨连续刚构桥梳齿板式伸缩缝为研究对象,采用ANSYS建立梳齿板式伸缩缝有限元模型,选用单车荷载模型,研究不同车速车辆荷载作用下的动力特性,同时研究不同超重比例和螺栓预紧力对伸缩缝动力特性的影响效果。计算分析结果表明:伸缩缝在动力作用下最不利位置为跨缝板桥缝中心位置;关键位置竖向位移随着缝宽的增加而明显增大;伸缩缝应力随着车辆速度的增加并非线性递增;跨缝板C位置和D位置在车速100 km/h时应力最大,缝宽从0增加到640 mm,跨缝板C位置应力增大53%,跨缝板D位置应力增大11%;单车移动荷载作用下,缝宽、超重比例与伸缩缝两关键位置应力值呈正相关关系;考虑安全性与性能提升,建议预紧力取45~55 kN。本研究聚焦伸缩缝最不利位置动力特性,为同类型梳齿板式伸缩缝性能评估提供依据。 展开更多
关键词 桥梁工程 连续刚构桥 大位移梳齿板式伸缩缝 车辆荷载 动力放大系数 动力响应
在线阅读 下载PDF
铜质换热器失效形式与成分显微分析
18
作者 刘兵 向雄志 +2 位作者 刘家荣 杨启欣 毛衍钦 《环境技术》 2025年第5期79-84,共6页
综合运用金相显微和电子显微技术,针对我国北方地区无氧铜换热器出现的漏水失效现象,开展了铜管腐蚀孔洞及管内外表面腐蚀产物的微观形貌表征与成分分析。结果表明:恶劣水质下,换热器失效的主要诱因为典型缝隙腐蚀、氧浓差电池效应与应... 综合运用金相显微和电子显微技术,针对我国北方地区无氧铜换热器出现的漏水失效现象,开展了铜管腐蚀孔洞及管内外表面腐蚀产物的微观形貌表征与成分分析。结果表明:恶劣水质下,换热器失效的主要诱因为典型缝隙腐蚀、氧浓差电池效应与应力腐蚀开裂。另外,当腐蚀产物层无法完整覆盖铜管内壁时,会加剧局部腐蚀进程并诱发点蚀;而连续致密的腐蚀产物层则可有效抑制均匀腐蚀的发展。本研究阐明了恶劣水质下无氧铜的腐蚀机理,为提升换热器材料的可靠性提供了参考。 展开更多
关键词 失效 可靠性 腐蚀行为 换热器
在线阅读 下载PDF
骨架材料增强污泥固化效果比较及其固化机理分析
19
作者 黄飞来 徐卫鑫 杨期勇 《九江学院学报(自然科学版)》 2025年第1期20-29,41,共11页
文章利用骨架构建来增强污泥固化效果,提出以水泥基固化剂为基础,高铁酸钾协同骨架材料的污泥固化工艺,探讨骨架材料增强固化污泥的固化机理。结果表明,秸秆纤维骨架材料增强污泥固化性能优于贝壳粉、粉煤灰和矿渣,最优配比为水泥20%、... 文章利用骨架构建来增强污泥固化效果,提出以水泥基固化剂为基础,高铁酸钾协同骨架材料的污泥固化工艺,探讨骨架材料增强固化污泥的固化机理。结果表明,秸秆纤维骨架材料增强污泥固化性能优于贝壳粉、粉煤灰和矿渣,最优配比为水泥20%、高铁酸钾10%、秸秆纤维5%,固化污泥无侧限抗压强度为126.87kPa,含水率为56%,满足污泥填埋要求(强度>50kPa,含水率<60%),制备成本为550元/吨。 展开更多
关键词 脱水污泥 污泥固化 骨架材料 无侧限抗压强度
在线阅读 下载PDF
基于YOLOv5的安全帽佩戴检测网络研究
20
作者 聂科恒 文娅 +2 位作者 范崇高 朱江 聂振东 《智能建筑电气技术》 2025年第4期103-111,129,共10页
针对复杂施工环境中小目标安全帽佩戴检测精度低、实时性差的问题,本文提出一种改进的基于YOLOv5的安全帽佩戴检测网络。首先,在主干特征提取网络中引入稠密连接模块Dense_C3,提升特征表达能力和细节捕获能力;其次,设计多尺度语义辅助... 针对复杂施工环境中小目标安全帽佩戴检测精度低、实时性差的问题,本文提出一种改进的基于YOLOv5的安全帽佩戴检测网络。首先,在主干特征提取网络中引入稠密连接模块Dense_C3,提升特征表达能力和细节捕获能力;其次,设计多尺度语义辅助特征池化模块(MSAFPNet),增强网络对小目标的定位与识别能力;最后,构建回归加权解耦检测头(RWDHead),通过分类与回归任务的解耦与协同,提升网络收敛速度并减少漏检。实验在SHWD安全帽佩戴检测公开数据集上进行,结果表明,所提网络在不显著增加模型参数和计算量的前提下,mAP50达到97.5%,推理速度达95.2FPS,优于当前主流目标检测算法,兼顾检测精度与实时性,具备良好的工程应用前景。研究成果可为智慧工地中施工人员安全监测提供技术支撑。 展开更多
关键词 智慧工地 小目标检测 深度学习 YOLOv5 解耦检测头
原文传递
上一页 1 2 25 下一页 到第
使用帮助 返回顶部