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A Novel Two-Layer Model for Overall Quality Assessment of Multichannel Audio
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作者 Jiyue Liu Jing Wang +2 位作者 Min Liu Xiang Xie Jingming Kuang 《China Communications》 SCIE CSCD 2017年第9期42-51,共10页
With the development of multichannel audio systems, corresponding audio quality assessment techniques, especially the objective prediction models, have received increasing attention. Existing methods, such as PEAQ(Per... With the development of multichannel audio systems, corresponding audio quality assessment techniques, especially the objective prediction models, have received increasing attention. Existing methods, such as PEAQ(Perceptual Evaluation of Audio Quality) recommended by ITU, usually lead to poor results when assessing multichannel audio, which have little correlation with subjective scores. In this paper, a novel two-layer model based on Multiple Linear Regression(MLR) and Neural Network(NN) is proposed. Through the first layer, two indicators of multichannel audio, Audio Quality Score(AQS) and Spatial Perception Score(SPS) are derived, and through the second layer the overall score is output. The final results show that this model can not only improve the correlation with the subjective test score by 30.7% and decrease the Root Mean Square Error(RMSE) by 44.6%, but also add two new indicators: AQS and SPS, which can help reflect the multichannel audio quality more clearly. 展开更多
关键词 MULTICHANNEL AUDIO two-layermodel AUDIO QUALITY assessment multiple lin-ear regression NEURAL network
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Similarities and differences in inherent mechanism and characteristic frequency between the one-dimensional poroelastic model and the layered White model
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作者 Li-Ming Zhao Cai-Ping Lu +1 位作者 Yang Liu Chao-Chao Li 《Petroleum Science》 SCIE EI CAS CSCD 2024年第4期2383-2392,共10页
The similarities and differences in inherent mechanism and characteristic frequency between the onedimensional(1D)poroelastic model and the layered White model were investigated.This investigation was conducted under ... The similarities and differences in inherent mechanism and characteristic frequency between the onedimensional(1D)poroelastic model and the layered White model were investigated.This investigation was conducted under the assumption that the rock was homogenous and isotropic at the mesoscopic scale.For the inherent mechanism,both models resulted from quasi-static flow in a slow P-wave diffusion mode,and the differences between them originated from saturated fluids and boundary conditions.On the other hand,for the characteristic frequencies of the models,the characteristic frequency of the 1D poroelastic model was first modified because the elastic constant and formula for calculating it were misused and then compared to that of the layered White model.Both of them moved towards higher frequencies with increasing permeability and decreasing viscosity and diffusion length.The differences between them were due to the diffusion length.The diffusion length for the 1D poroelastic model was determined by the sample length,whereas that for the layered White model was determined by the length of the representative elementary volume(REV).Subsequently,a numerical example was presented to demonstrate the similarities and differences between the models.Finally,published experimental data were interpreted using the 1D poroelastic model combined with the Cole-Cole model.The prediction of the combined model was in good agreement with the experimental data,thereby validating the effectiveness of the 1D poroelastic model.Furthermore,the modified characteristic frequency in our study was much closer to the experimental data than the previous prediction,validating the effectiveness of our modification of the characteristic frequency of the 1D poroelastic model.The investigation provided insight into the internal relationship between wave-induced fluid flow(WIFF)models at macroscopic and mesoscopic scales and can aid in a better understanding of the elastic modulus dispersion and attenuation caused by the WIFF at different scales. 展开更多
关键词 1D poroelastic model layered White model Quasi-static flow Slow P-wave diffusion Characteristic frequency Diffusion length
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Three-Dimensional Simulations of RESET Operation in Phase-Change Random Access Memory with Blade-Type Like Phase Change Layer by Finite Element Modeling 被引量:2
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作者 金秋雪 刘波 +8 位作者 刘燕 王维维 汪恒 许震 高丹 王青 夏洋洋 宋志棠 封松林 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第9期128-131,共4页
An optimized device structure for reducing the RESET current of phase-change random access memory (PCRAM) with blade-type like (BTL) phase change layer is proposed. The electrical thermal analysis of the BTL cell ... An optimized device structure for reducing the RESET current of phase-change random access memory (PCRAM) with blade-type like (BTL) phase change layer is proposed. The electrical thermal analysis of the BTL cell and the blade heater contactor structure by three-dimensional finite element modeling are compared with each other during RESET operation. The simulation results show that the programming region of the phase change layer in the BTL cell is much smaller, and thermal electrical distributions of the BTL cell are more concentrated on the TiN/GST interface. The results indicate that the BTL cell has the superiorities of increasing the heating efficiency, decreasing the power consumption and reducing the RESET current from 0.67mA to 0.32mA. Therefore, the BTL cell will be appropriate for high performance PCRAM device with lower power consumption and lower RESET current. 展开更多
关键词 PCRAM cell RESET Three-Dimensional Simulations of RESET Operation in Phase-Change Random Access Memory with Blade-Type Like Phase Change layer by Finite Element modeling of by in with
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Asymptotic solution of a weak nonlinear model for the mid-latitude stationary wind field of a two-layer barotropic ocean 被引量:8
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作者 林万涛 张宇 莫嘉琪 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第3期72-78,共7页
A weak nonlinear model of a two-layer barotropic ocean with Rayleigh dissipation is built.The analytic asymptotic solution is derived in the mid-latitude stationary wind field,and the physical meaning of the correspon... A weak nonlinear model of a two-layer barotropic ocean with Rayleigh dissipation is built.The analytic asymptotic solution is derived in the mid-latitude stationary wind field,and the physical meaning of the corresponding problem is discussed. 展开更多
关键词 two-layer barotropic ocean ocean model asymptotic solution
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Critical properties of XY model dimensional layered magnetic on two- films
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作者 王漪 刘晓彦 +2 位作者 孙雷 张兴 韩汝琦 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第5期1081-1085,共5页
Using Monte Carlo simulations, we have investigated the classical XY model on triangular lattices of ultra-thin film structures with middle ferromagnetic layers sandwiched between two antiferromagnetic layers. The int... Using Monte Carlo simulations, we have investigated the classical XY model on triangular lattices of ultra-thin film structures with middle ferromagnetic layers sandwiched between two antiferromagnetic layers. The internal energy, the specifc heat, the chirality and the chiral susceptibility are calculated in order to clarify phase transitions and critical phenomena. Prom the finite-size scaling analyses, the values of critical exponents are determined. In a range of interaction parameters, we find that the chirality steeply goes up as temperature increases in a temperature range; correspondingly the value of a critical exponent for this change is estimated. 展开更多
关键词 layered XY model critical phenomena ultra-thin magnetic film
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Breakdown voltage model and structure realization of a thin silicon layer with linear variable doping on a silicon on insulator high voltage device with multiple step field plates 被引量:2
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作者 乔明 庄翔 +4 位作者 吴丽娟 章文通 温恒娟 张波 李肇基 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第10期504-511,共8页
Based on the theoretical and experimental investigation of a thin silicon layer(TSL) with linear variable doping(LVD) and further research on the TSL LVD with a multiple step field plate(MSFP),a breakdown voltag... Based on the theoretical and experimental investigation of a thin silicon layer(TSL) with linear variable doping(LVD) and further research on the TSL LVD with a multiple step field plate(MSFP),a breakdown voltage(BV) model is proposed and experimentally verified in this paper.With the two-dimensional Poisson equation of the silicon on insulator(SOI) device,the lateral electric field in drift region of the thin silicon layer is assumed to be constant.For the SOI device with LVD in the thin silicon layer,the dependence of the BV on impurity concentration under the drain is investigated by an enhanced dielectric layer field(ENDIF),from which the reduced surface field(RESURF) condition is deduced.The drain in the centre of the device has a good self-isolation effect,but the problem of the high voltage interconnection(HVI) line will become serious.The two step field plates including the source field plate and gate field plate can be adopted to shield the HVI adverse effect on the device.Based on this model,the TSL LVD SOI n-channel lateral double-diffused MOSFET(nLDMOS) with MSFP is realized.The experimental breakdown voltage(BV) and specific on-resistance(R on,sp) of the TSL LVD SOI device are 694 V and 21.3 ·mm 2 with a drift region length of 60 μm,buried oxide layer of 3 μm,and silicon layer of 0.15 μm,respectively. 展开更多
关键词 breakdown voltage model enhanced dielectric layer field thin silicon layer linear variable doping multiple step field plates
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Modeling TCP Incast Issue in Data Center Networks and an Adaptive Application-Layer Solution
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作者 Jin-Tang Luo Jie Xu Jian Sun 《Journal of Electronic Science and Technology》 CAS CSCD 2018年第1期84-91,共8页
In data centers, the transmission control protocol(TCP) incast causes catastrophic goodput degradation to applications with a many-to-one traffic pattern. In this paper, we intend to tame incast at the receiver-side a... In data centers, the transmission control protocol(TCP) incast causes catastrophic goodput degradation to applications with a many-to-one traffic pattern. In this paper, we intend to tame incast at the receiver-side application. Towards this goal, we first develop an analytical model that formulates the incast probability as a function of connection variables and network environment settings. We combine the model with the optimization theory and derive some insights into minimizing the incast probability through tuning connection variables related to applications. Then,enlightened by the analytical results, we propose an adaptive application-layer solution to the TCP incast.The solution equally allocates advertised windows to concurrent connections, and dynamically adapts the number of concurrent connections to the varying conditions. Simulation results show that our solution consistently eludes incast and achieves high goodput in various scenarios including the ones with multiple bottleneck links and background TCP traffic. 展开更多
关键词 Application-layer solution data center networks modelING transmission control protocol(TCP) incast
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Dynamic Visual Image Modeling Based on Mobile RobotSelf- Organizing Network in Internetof Things Perception Layer 被引量:1
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作者 高立 任旭鹏 李晓博 《China Communications》 SCIE CSCD 2011年第8期49-55,共7页
The dynamic multichannel binocular visual image modeling is studied based on Internet of Things (IoT) Perception Layer, using mobile robot self-organizing network. By employing multigroup mobile robots with binocular ... The dynamic multichannel binocular visual image modeling is studied based on Internet of Things (IoT) Perception Layer, using mobile robot self-organizing network. By employing multigroup mobile robots with binocular visual system, the real visual images of the object will be obtained. Then through the mobile self-organizing network, a three-dimensional model is rebuilt by synthesizing the returned images. On this basis, we formalize a novel algorithm for multichannel binocular visual three-dimensional images based on fast three-dimensional modeling. Compared with the method based on single binocular visual system, the new algorithm can improve the Integrity and accuracy of the dynamic three-dimensional object modeling. The simulation results show that the new method can effectively accelerate the modeling speed, improve the similarity and not increase the data size. 展开更多
关键词 IoT perception layer multigroup binocular visual dynamic visual image modeling fast three-dimensional modeling rebuild
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改进YOLOv7和SeaFormer的桥梁裂缝识别与测量
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作者 杨国俊 齐亚辉 +1 位作者 杜永峰 石秀名 《铁道科学与工程学报》 北大核心 2025年第1期429-442,共14页
为解决以往桥梁裂缝检测模型参数量大、检测效率低、延迟高,无人机采集图像质量不佳等问题,引入图像质量评价模型和SeaFormer轻量化语义分割算法,通过改进YOLOv7目标检测算法,训练并建立基于改进的YOLOv7和SeaFormer的桥梁裂缝识别与分... 为解决以往桥梁裂缝检测模型参数量大、检测效率低、延迟高,无人机采集图像质量不佳等问题,引入图像质量评价模型和SeaFormer轻量化语义分割算法,通过改进YOLOv7目标检测算法,训练并建立基于改进的YOLOv7和SeaFormer的桥梁裂缝识别与分割一体化模型,提出基于内切圆的裂缝长度与宽度像素级计算方法。同时,采用先识别,然后将裂缝识别目标框图像作为分割模型的输入图像进行分割,再将分割图像进行处理并按照目标框位置信息映射回原图的方案,大大提高了裂缝的检测效率;利用本文质量评估模型筛选并标注公开混凝土桥梁裂缝图像,作为本文模型数据集。通过在此数据集上与主流模型进行训练测试对比,证明了本文算法在精度、轻量化等方面的优势。然后利用大疆精灵4pro-v2.0无人机在距离待测面3m处采集结构裂缝图像进行精度验证,裂缝宽度检测相对误差在18%以内,裂缝长度检测相对误差在10%以内。另外,在加入兰州市中山桥桥墩裂缝图像的混合测试集中,裂缝识别定位精准度达91.38%,F1分数88.94%,召回率86.62%;裂缝分割准确度为93.66%,交并比90.17%。研究结果表明:基于改进YOLOv7和SeaFormer的一体化桥梁裂缝检测方法在兼顾检测速度与精度的情况下,模型更小、检测效率更高,更适用于搭载在无人机等移动设备进行桥梁、高塔等结构的裂缝检测。 展开更多
关键词 桥梁工程 裂缝检测 无人机 深度学习 轻型多层感知模块 YOLOv7模型 SeaFormer模型
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基于多核数据合成的离线小数据驱动的进化算法
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作者 李二超 刘昀 《浙江大学学报(工学版)》 北大核心 2025年第2期278-288,共11页
为了增强离线数据驱动的进化算法在小数据情景中的表现,削弱代理模型对数据集规模的依赖,提出基于多核数据合成的离线小数据驱动的进化算法(DDEA-MKDS).考虑到代理模型易因小数据陷入过拟合,通过经验公式与遍历法找出针对离线数据集的... 为了增强离线数据驱动的进化算法在小数据情景中的表现,削弱代理模型对数据集规模的依赖,提出基于多核数据合成的离线小数据驱动的进化算法(DDEA-MKDS).考虑到代理模型易因小数据陷入过拟合,通过经验公式与遍历法找出针对离线数据集的最优隐含层节点数,以简化模型结构.为了弥补数据量的不足,训练了3个不同核函数的径向基网络生成合成数据,通过轮盘赌法选择其中的部分数据与原数据集合并,使用新数据集训练代理模型.将DDEA-MKDS与其他5种流行的离线数据驱动的进化算法在6个单目标基准测试问题上进行对比,实验结果表明,所提算法在数据量极小的条件下能够取得良好的效果,寻优效率显著优于其他算法. 展开更多
关键词 离线数据驱动 进化算法 小数据 代理模型 隐含层节点 合成数据
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基于连续导电通道计算的低对比度油层评价方法
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作者 张美玲 赵佳慧 +1 位作者 熊葵 王双全 《测井技术》 2025年第1期10-16,30,共8页
低对比度油层解释一直是测井评价难题,而福山凹陷涠洲组高产油层电阻率与水层电阻率相近的情况严重影响了油藏储量计算。黏土阳离子交换模型是一种有效的低电阻率油层评价模型,但难以解释涠洲组黏土类型及其含量均存在较大差别的低电阻... 低对比度油层解释一直是测井评价难题,而福山凹陷涠洲组高产油层电阻率与水层电阻率相近的情况严重影响了油藏储量计算。黏土阳离子交换模型是一种有效的低电阻率油层评价模型,但难以解释涠洲组黏土类型及其含量均存在较大差别的低电阻率油层。基于电场等效电路原理,构建束缚水连通导电模型,并采用有限元数值技术及欧姆定律计算模型等效电阻率。优选涠洲组物性条件相当、黏土类型差别大的低对比度油层,分别采用阳离子交换模型和束缚水连通导电模型进行计算,发现由束缚水连通导电模型计算的电阻率与实际井测量值吻合更好,能够更有效地解释涠洲组低对比度油层,为涠洲组油藏储量评估提供了可靠依据。束缚水连通导电模型从电场基本理论出发,不受岩层中黏土类型及其分布等复杂微观因素限制,该方法具有普适性和推广价值。 展开更多
关键词 测井 涠洲组 低对比度油层 电阻率 连续导电模型
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考虑过渡层多层空间变异性的边坡降雨入渗模型及稳定性分析应用
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作者 蒋水华 元志镕 +2 位作者 刘贤 黄劲松 周创兵 《岩土工程学报》 北大核心 2025年第2期255-264,共10页
建立合理的降雨入渗模型是揭示降雨诱发边坡失稳机制及灾害防控的重要前提。传统的Green-Ampt模型未考虑土壤分层及雨水入渗形成的过渡层分布,导致计算的入渗率存在较大偏差,难以适用于空间变异性边坡。提出土层入渗率的分层求解方法,... 建立合理的降雨入渗模型是揭示降雨诱发边坡失稳机制及灾害防控的重要前提。传统的Green-Ampt模型未考虑土壤分层及雨水入渗形成的过渡层分布,导致计算的入渗率存在较大偏差,难以适用于空间变异性边坡。提出土层入渗率的分层求解方法,可由不同土层间入渗率大小关系确定过渡层厚度,据此提出考虑土体饱和渗透系数空间变异性边坡降雨入渗分析的改进Green-Ampt模型。进而应用改进模型进行降雨入渗下均质和非均质无限长边坡渗流及稳定性分析,并与传统Green-Ampt模型计算结果和Richards方程数值解加以对比。分析结果表明:相比于传统的Green-Ampt模型,利用改进模型计算的边坡体积含水量分布和稳定性系数与Richards方程数值解更为吻合,可以更好地为非均质边坡降雨入渗分析及降雨型滑坡灾害防控提供理论依据。此外,发现过渡层厚度与土体饱和渗透系数、过渡层顶部入渗率和体积含水量之间存在依赖关系,而与雨水入渗的总深度无直接关系。 展开更多
关键词 边坡稳定性分析 空间变异性 降雨入渗 改进Green-Ampt模型 过渡层
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考虑接触刚度的航空发动机模拟整机模型降维及修正
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作者 高程明 何俊增 +4 位作者 刘家璇 姜东 卢愈 张大海 费庆国 《推进技术》 北大核心 2025年第1期264-274,共11页
针对航空发动机建模过程中普遍存在的精确度和计算效率难以同时满足的问题,提出了一种考虑接触刚度的航空发动机模拟整机模型降维及修正方法。分别建立航空发动机转子和机匣的三维有限元模型,并运用薄层单元来模拟转子轮盘间的端齿接触... 针对航空发动机建模过程中普遍存在的精确度和计算效率难以同时满足的问题,提出了一种考虑接触刚度的航空发动机模拟整机模型降维及修正方法。分别建立航空发动机转子和机匣的三维有限元模型,并运用薄层单元来模拟转子轮盘间的端齿接触以及机匣间的螺栓接触界面;基于固定界面模态综合法,对模型进行降维处理,保留接触界面和支承位置处的关键主节点,分别得到转子和机匣的降维模型;运用灵敏度方法,结合转子模态试验和机匣模态试验的结果,对转子和机匣降维模型中的接触刚度进行修正;将修正后的转子降维模型和机匣降维模型进行组装,得到航空发动机模拟整机模型。开展模拟整机模态试验,将修正后的模拟整机模型的计算结果与试验数据进行对比。结果表明,修正后的模型前两阶弯曲模态频率误差控制在1.22%以内,且以Matlab软件为计算平台,进行了五次迭代修正计算,平均每次计算时长仅为2.1 s,验证了所提方法的准确性和高效性。研究结果为航空发动机建模及修正提供了一种新的有效手段,在满足了航空发动机模拟整机修正精度的同时,显著提高了模型修正的计算效率。 展开更多
关键词 航空发动机模拟整机 模型修正 薄层单元 降维 接触刚度
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基于数据挖掘的光传送网路由波长优化研究
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作者 刘全智 武爽 《激光杂志》 北大核心 2025年第2期193-197,共5页
为解决当前光传送网面临的日益增长的数据传输需求与有限的网络资源之间的矛盾,设计基于数据挖掘的光传送网路由波长优化方法。构建分层图模型,将物理链路中的波长资源映射为图形结构中的连接线,在同一框架内解决路由和波长分配问题,利... 为解决当前光传送网面临的日益增长的数据传输需求与有限的网络资源之间的矛盾,设计基于数据挖掘的光传送网路由波长优化方法。构建分层图模型,将物理链路中的波长资源映射为图形结构中的连接线,在同一框架内解决路由和波长分配问题,利用遗传算法设计网络负载动态适应算法,实现光传送网网络负载动态适应优化,从而实现路由、波长的共同优化。实验测试结果表明,该方法在整个测试过程中都保持较低的阻塞指数,随着业务数的增加,阻塞指数上升速度慢,资源利用指数在业务数初期增长快,随后逐渐平稳,最终达到接近0.7的资源利用指数。 展开更多
关键词 数据挖掘 用户识别 光传送网 分层图模型 路由波长优化
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A Model for the Sounding Rocket Measurement on an Ionospheric E-F Valley at the Hainan Low Latitude Station
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作者 王铮 史建魁 +4 位作者 关燚炳 刘超 朱光武 Klaus TORKAR Martin FREDRICH 《Plasma Science and Technology》 SCIE EI CAS CSCD 2014年第4期316-319,共4页
To understand the physics of an ionospheric E-F valley, a new overlapping three- Chapman-layer model is developed to interpret the sounding rocket measurement in the morn- ing (sunrise) on May 7, 2011 at the Hainan ... To understand the physics of an ionospheric E-F valley, a new overlapping three- Chapman-layer model is developed to interpret the sounding rocket measurement in the morn- ing (sunrise) on May 7, 2011 at the Hainan low latitude ionospheric observation station (19.5°N, 109.1°E). From our model, the valley width, depth and height are 43.0 km, 62.9% and 121.0 km, re- spectively. From the sounding rocket observation, the valley width, depth and height are 42.2 km, 47.0% and 123.5 km, respectively. The model results are well consistent with the sounding rocket observation. The observed E-F valley at Hainan station is very wide and deep, and rapid deel- opment of the photochemical process in the ionosphere should be the underlying reason. 展开更多
关键词 Chapman theory overlapping three-layer model ionospheric E-F valley
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薄层罩面及泡沫温拌沥青养护工艺碳排放对比分析
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作者 赵跃 李明亮 +1 位作者 李俊 李韧菲 《交通节能与环保》 2025年第1期171-175,共5页
论文研究了薄层罩面及泡沫温拌沥青养护过程的碳排放影响因素,建立了薄层罩面及泡沫温拌沥青养护工艺碳排放计算模型;并基于实际养护工程,对比分析了薄层罩面及泡沫温拌沥青不同施工阶段的碳排放量。结果表明,在薄层罩面养护工艺中,采... 论文研究了薄层罩面及泡沫温拌沥青养护过程的碳排放影响因素,建立了薄层罩面及泡沫温拌沥青养护工艺碳排放计算模型;并基于实际养护工程,对比分析了薄层罩面及泡沫温拌沥青不同施工阶段的碳排放量。结果表明,在薄层罩面养护工艺中,采用干法SBS及泡沫温拌技术均可减少养护过程中产生的碳排放。 展开更多
关键词 道路工程 养护 碳排放计算模型 薄层罩面 泡沫温拌沥青
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考虑需求响应的分布式光伏储能系统双层优化配置
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作者 周强 姚朴 《能源与环保》 2025年第1期155-160,共6页
分布式光伏渗透率的不断提高和储能技术的日益成熟对配电网的规划运行提出了更高要求。在分布式光伏储能系统的规划运行过程中为了充分挖掘负荷的需求响应潜力,提出了考虑需求响应的规划—运行双层优化配置方法。上层考虑储能荷电状态... 分布式光伏渗透率的不断提高和储能技术的日益成熟对配电网的规划运行提出了更高要求。在分布式光伏储能系统的规划运行过程中为了充分挖掘负荷的需求响应潜力,提出了考虑需求响应的规划—运行双层优化配置方法。上层考虑储能荷电状态、需求响应等约束条件并以投资成本为目标来确定光伏和储能的选址定容方案;下层以运行成本和电压偏移为目标,采用改进多目标粒子群算法得到Pareto前沿解集,并将最佳结果带入到上层模型进行求解。最后,采用IEEE 33节点系统验证了所提优化配置方法的有效性。 展开更多
关键词 分布式光伏 分布式储能 需求响应 双层模型 多目标粒子群算法 选址定容
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层状介质半航空瞬变电磁正反演研究及应用
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作者 姚辉 李论 +4 位作者 闻海坡 吴向斌 郭伟 李盼盼 蔚波 《科技创新与应用》 2025年第3期8-13,共6页
半航空瞬变电磁具有信噪比高、探测深度大,可以实现高效和适应复杂地形条件下对目标体探测等优点。目前该方法的正反演研究和应用都得到较快的发展。该文以电性源半航空瞬变电磁为例,利用数值模拟方法得到层状介质中瞬变电磁响应。建立... 半航空瞬变电磁具有信噪比高、探测深度大,可以实现高效和适应复杂地形条件下对目标体探测等优点。目前该方法的正反演研究和应用都得到较快的发展。该文以电性源半航空瞬变电磁为例,利用数值模拟方法得到层状介质中瞬变电磁响应。建立K型地电模型和H型地电模型分析地层参数对瞬变电磁响应的影响。分析结果表明,埋深较浅的低阻层不利于半航空瞬变电磁对异常体的探测,高阻层厚越大或埋深较浅越容易被探测,而且当中间层与围岩电阻率差异越大,对瞬变电磁响应影响越大。然后根据某井工矿水文地质资料,建立充水采空区模型和砂岩裂隙含水层模型,基于自适应正则化反演方法对理论模型进行试算,发现该反演方法能够反映出砂岩裂隙含水层,能够较为准确地反映出异常体的位置,但对目的层厚度较薄的积水采空区模型反演效果较差。最后,为了验证电性源半航空瞬变电磁系统实际应用效果,对某煤矿进行探测。结果表明,该系统可有效地揭示探测区域的视电阻率差异性分布。因此,电性源半航空瞬变电磁是一种高效、适应复杂探测环境、分辨率较高的探测方法。 展开更多
关键词 电性源半航空瞬变电磁 层状模型响应特征 自适应正则化反演 富水性探测 瞬变电磁响应
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引射工质对高温高超声速层/湍流边界流动的影响
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作者 吴心怡 张伦 +3 位作者 张雨秋 江中正 吴昌聚 陈伟芳 《上海航天(中英文)》 2025年第1期169-179,共11页
高超声速飞行器面临剧烈气动热问题,对飞行器热防护构成威胁,通过质量引射的主动热防护技术能够有效地降低壁面的摩擦阻力和热流,成为热防护研究的热点。然而,不同工质引射对高温高超声速层/湍流边界层流动的影响规律及区别仍不十分明确... 高超声速飞行器面临剧烈气动热问题,对飞行器热防护构成威胁,通过质量引射的主动热防护技术能够有效地降低壁面的摩擦阻力和热流,成为热防护研究的热点。然而,不同工质引射对高温高超声速层/湍流边界层流动的影响规律及区别仍不十分明确,是主动热防护设计亟须解决的气动问题。因此,本文拟选取二维平板模型,采用剪切应力输运(SST)湍流模型,开展考虑质量引射的降热减阻数值模拟研究,分析了3种不同引射工质(水蒸汽、二氧化碳、热解气体)对高温高超声速层/湍流流动的影响。计算结果说明:热解气体引射条件下,层/湍流激波层速度和温度分布差异明显。与无引射相比,3种不同工质引射气体均有效降低了湍流边界层处的速度与温度梯度,进而降低了壁面的摩擦阻力和热流,并且相较于其他2种工质,热解气体引射降热减阻效果最为显著。研究结果还表明:3种引射工质均使得雷诺应力大幅度提升,加剧了湍流的脉动。 展开更多
关键词 壁面质量引射 剪切应力输运(SST)模型 边界层 降热减阻 化学反应
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MPEG Audio I Layer Ⅲ的几个问题
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作者 亓中瑞 高振明 《山东电子》 2003年第4期40-42,共3页
本文主要介绍了MPEGAudioILayerIII的一些基本原理 ,包括为什么要用MP3格式进行声音文件的传输、音频文件可以被压缩的原因。
关键词 MPEG-Audio-I-layerⅢ的几个问题 MP3格式 声音文件 心理声学模型 滤波器组
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