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&gamma 1

CCK-8 实验 1

GVG农情采样系统 1

Gibbs抽样 1

MCMC模拟 1

MTT 实验 1

PCB缺陷检测 1

Weibull分布 1

mcr 1

人工智能 1

人脸建模 1

作物灾情 1

共享异质性模型 1

几何构造 1

十二烷基硫酸钠&ndash 1

压缩采样 1

压缩采样；单像素成像；光子时间拉伸；成像式流式细胞仪 1

可靠性 1

四元数傅里叶变换；四元数线性正则变换；采样定理；部分和总体四元数希尔伯特变换；部分和总体广义四元数希尔伯特变换；截断误差 1

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A sampling method based on URL clustering for fast web accessibility evaluation

Meng-ni ZHANG,Can WANG,Jia-jun BU,Zhi YU,Yu ZHOU,Chun CHEN

《信息与电子工程前沿（英文）》 2015年第16卷第6期页码 449-456 doi: 10.1631/FITEE.1400377

摘要： When evaluating the accessibility of a large website, we rely on sampling methods to reduce the cost of evaluation. This may lead to a biased evaluation when the distribution of checkpoint violations in a website is skewed and the selected samples do not provide a good representation of the entire website. To improve sampling quality, stratified sampling methods first cluster web pages in a site and then draw samples from each cluster. In existing stratified sampling methods, however, all the pages in a website need to be analyzed for clustering, causing huge I/O and computation costs. To address this issue, we propose a novel page sampling method based on URL clustering for web accessibility evaluation, namely URLSamp. Using only the URL information for stratified page sampling, URLSamp can efficiently scale to large websites. Meanwhile, by exploiting similarities in URL patterns, URLSamp cluster pages by their generating scripts and can thus effectively detect accessibility problems from web page templates. We use a data set of 45 web sites to validate our method. Experimental results show that our URLSamp method is both effective and efficient for web accessibility evaluation.

关键词： Page sampling URL clustering Web accessibility evaluation

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Numerical simulation and experimental research on the wheel brush sampling process of an asteroid sampler

《机械工程前沿（英文）》 2023年第18卷第2期 doi: 10.1007/s11465-022-0732-0

摘要： To examine the environmental characteristics of the microgravity force and the weathered layer on an asteroid surface, a symmetric wheel brush asteroid sampler is proposed for the collection of particles on the asteroid surface. To study the influence of the wheel brush rotation speed on the sampling efficiency and the driving torque required for the wheel brush, the contact dynamics model between particles and sampling wheel brushes is established and a simulation and experimental verification of the sampling process are conducted. The parameter calibration of the sampled particles is studied first, and the calibrated particle parameters are used in the numerical simulation of the sampling process. The sampling results and the particle stream curves are obtained for the working conditions of different rotation speeds, and the effects of different parameter settings on the sampling efficiency are analyzed. In addition, a set of rotating symmetrical sampling wheel brush devices is built for the ground test, and the dynamic torque sensor is used to test the torque change of the wheel brush during the sampling process. The relationship between the speed of the wheel brush and the driving torque of the wheel brush motor is determined by comparing the simulation results with the test results. Results indicate that when the rotating speed of the wheel brush is faster, the sampling efficiency is higher, and the driving torque required for the sampling wheel brush is greater. Moreover, a numerical simulation analysis of the sampling process of the wheel brush sampler in a microgravity environment is conducted to determine the optimal speed condition, and the brushing test of the wheel brush sampler in the microgravity environment is verified with the drop tower method. This research proposes the structural optimization design and motor selection of a wheel brush asteroid sampler, which provides important reference value and engineering significance.

关键词： asteroid sampling wheel brush sampler discrete element method parameter calibration experimental research

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Fifty Years of Water Sensitive Urban Design, Salisbury, South Australia

Radcliffe, Declan Page, Bruce Naumann, Peter Dillon

《环境科学与工程前沿（英文）》 2017年第11卷第4期 doi: 10.1007/s11783-017-0937-3

摘要： Australia has developed extensive policies and guidelines for the management of its water. The City of Salisbury, located within metropolitan Adelaide, South Australia, developed rapidly through urbanisation from the 1970s. Water sensitive urban design principles were adopted to maximise the use of the increased run-off generated by urbanisation and ameliorate flood risk. Managed aquifer recharge was introduced for storing remediated low-salinity stormwater by aquifer storage and recovery (ASR) in a brackish aquifer for subsequent irrigation. This paper outlines how a municipal government has progressively adopted principles of Water Sensitive Urban Design during its development within a framework of evolving national water policies. Salisbury’s success with stormwater harvesting led to the formation of a pioneering water business that includes linking projects from nine sites to provide a non-potable supply of 5 × 10 m ·year . These installations hosted a number of applied research projects addressing well configuration, water quality, reliability and economics and facilitated the evaluation of its system as a potential potable water source. The evaluation showed that while untreated stormwater contained contaminants, subsurface storage and end-use controls were sufficient to make recovered water safe for public open space irrigation, and with chlorination, acceptable for third pipe supplies. Drinking water quality could be achieved by adding microfiltration, disinfection with UV and chlorination. The costs that would need to be expended to achieve drinking water safety standards were found to be considerably less than the cost of establishing dual pipe distribution systems. The full cost of supply was determined to be AUD$1.57 m for non-potable water for public open space irrigation, much cheaper than mains water, AUD$3.45 m at that time. Producing and storing potable water was found to cost AUD$1.96 to $2.24 m .

关键词： Managed Aquifer Recharge (MAR) Stormwater harvesting Water recycling drinking water Low impact development Water sensitive urban design

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Investigation on sampling artifacts of particle associated PAHs using ozone denuder systems

Kai LIU, Fengkui DUAN, Kebin HE, Yongliang MA, Yuan CHENG

《环境科学与工程前沿（英文）》 2014年第8卷第2期页码 284-292 doi: 10.1007/s11783-013-0555-7

摘要： Polycyclic aromatic hydrocarbons (PAHs) are complex organic compounds which are identified as significant carcinogenic to human health. PAHs (mainly in particle phase) are susceptible to atmospheric oxidant gases, especially ozone, nitrogen oxides (NO ), hydroxyl radical (OH), and could be degraded on filters during sampling process, leading to an underestimation of ambient PAH concentrations. The goal of this work was to investigate particle associated PAHs sampling artifacts caused by ozone in summer of Beijing. Comparative sampling systems were operated simultaneously during the whole campaign, one with activated carbon ozone denuder, the other being set as conventional sampling system. Activated carbon denuder was testified to be highly efficient to eliminate ozone from air stream. In general, nine particle-bound PAHs observed from conventional sampler were all lower than those from ozone denuder system. The total PAHs (particle phase) concentration was averagely underestimated by 35.9% in conventional sampling procedure. Benzo[a]pyrene (BaP) had the highest percentage of mass loss. Ambient temperature was founded to have influences on PAHs sampling artifacts. High temperature can increase loss of particle associated PAHs during sampling.

关键词： particle associated polycyclic aromatic hydrocarbons (PAHs) ozone denuder sampling artifacts

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Combustion analysis of a hydrogen-diesel fuel operated DI diesel engine with exhaust gas recirculation

VELMURUGAN, TOM PAGE, E. JAMES GUNASEKARAN, P. TAMILARASAN

《能源前沿（英文）》 2017年第11卷第4期页码 568-574 doi: 10.1007/s11708-017-0461-y

摘要： The rapid depletion of fossil fuel and growing demand necessitates researchers to find alternative fuels which are clean and sustainable. The need for finding renewable, low cost and environmentally friendly fuel resources can never be understated. An efficient method of generation and storage of hydrogen will enable automotive manufacturers to introduce hydrogen fuelled engine in the market. In this paper, a conventional DI diesel engine was modified to operate as gas engine. The intake manifold of the engine was supplied with hydrogen along with recirculated exhaust gas and air. The injection rates of hydrogen were maintained at three levels with 2 L/min, 4 L/min, 6 L/min and 8 L/min and 10 L/min with an injection pressure of 2 bar. Many of the combustion parameters like heat release rate (HRR), ignition delay, combustion duration, rate of pressure rise (ROPR), cumulative heat release rate (CHR), and cyclic pressure fluctuations were measured. The HRR peak pressure decreased with the increase in EGR rate, while combustion duration increased with the EGR rate. The cyclic pressure variation also increased with the increase in EGR rate.

关键词： hydrogen exhaust gas recirculation (EGR) diesel combustion heat release rate (HRR) combustion duration

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Dilution sampling and analysis of particulate matter in biomass-derived syngas

Xiaoliang WANG, Curtis ROBBINS, S. Kent HOEKMAN, Judith C. CHOW, John G. WATSON, Dennis SCHUETZLE

《环境科学与工程前沿（英文）》 2011年第5卷第3期页码 320-330 doi: 10.1007/s11783-011-0347-x

摘要： Thermochemical biomass gasification, followed by conversion of the produced syngas to fuels and electrical power, is a promising energy alternative. Real-world characterization of particulate matter (PM) and other contaminants in the syngas is important to minimize damage and ensure efficient operation of the engines it powers and the fuels created from it. A dilution sampling system is demonstrated to quantify PM in syngas generated from two gasification plants utilizing different biomass feedstocks: a BioMax 15 Biopower System that uses raw and torrefied woodchips as feedstocks, and an integrated biorefinery (IBR) that uses rice hulls and woodchips as feedstocks. PM mass concentrations in syngas from the IBR downstream of the purification system were 12.8–13.7 μg·m , which were significantly lower than the maximum level for catalyst protection (500 μg·m ) and were 2–3 orders of magnitude lower than those in BioMax 15 syngas (2247–4835 μg·m ). Ultrafine particle number concentration and PM chemical constituents were also much lower in the IBR syngas than in the BioMax 15. The dilution sampling system enabled reliable measurements over a wide range of concentrations: the use of high sensitivity instruments allowed measurement at very low concentrations (~1 μg·m ), while the flexibility of dilution minimized sampling problems that are commonly encountered due to high levels of tars in raw syngas (~1 g·m ).

关键词： dilution source sampling syngas characterization biomass gasification ultrafine particles

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Unified methodology for site-characterization and sampling of highway runoff

Jy S. WU, Craig J. ALLAN,

《环境科学与工程前沿（英文）》 2010年第4卷第1期页码 47-58 doi: 10.1007/s11783-010-0003-x

摘要： Hydrology, roadway traffic conditions, and atmospheric deposition are three essential data categories for the planning and implementation of highway-runoff monitoring and characterization programs. Causal variables pertaining to each data category could be site specific but have been shown to correlate with runoff pollutant loads. These data categories were combined to derive statistical relationships for characterization and prioritization of the respective pollutant loads at highway runoff sites. Storm runoff data of total suspended solids (TSS), total dissolved solid (TDS), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN) and total phosphorus (TP) collected from three highway sites in Charlotte, North Carolina, USA, were used to illustrate the development of site-specific highway-runoff pollutant loading models. This unified methodology provides a basis for initial assessment of the pollutant-constituent loads from highway runoff using hydrologic component variables. Improved reliability is achievable when additional traffic and/or atmospheric component variables are incorporated into the basic hydrologic regression model. In addition, operational guidance is suggested for implementing highway-runoff monitoring programs that are subject to sampling and resources constraints.

关键词： highway runoff pollutant loads regression models non-point source pollution storm water permit

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Uncertainty propagation in dynamics of composite plates: A semi-analytical non-sampling-based approach

Mahdi FAKOOR, Hadi PARVIZ

《结构与土木工程前沿（英文）》 2020年第14卷第6期页码 1359-1371 doi: 10.1007/s11709-020-0658-8

摘要： In this study, the influences of spatially varying stochastic properties on free vibration analysis of composite plates were investigated via development of a new approach named the deterministic-stochastic Galerkin-based semi-analytical method. The material properties including tensile modulus, shear modulus, and density of the plate were assumed to be spatially varying and uncertain. Gaussian fields with first-order Markov kernels were utilized to define the aforementioned material properties. The stochastic fields were decomposed via application of the Karhunen-Loeve theorem. A first-order shear deformation theory was assumed, following which the displacement field was defined using admissible trigonometric modes to derive the potential and kinetic energies. The stochastic equations of motion of the plate were obtained using the variational principle. The deterministic-stochastic Galerkin-based method was utilized to find the probability space of natural frequencies, and the corresponding mode shapes of the plate were determined using a polynomial chaos approach. The proposed method significantly reduced the size of the mathematical models of the structure, which is very useful for enhancing the computational efficiency of stochastic simulations. The methodology was verified using a stochastic finite element method and the available results in literature. The sensitivity of natural frequencies and corresponding mode shapes due to the uncertainty of material properties was investigated, and the results indicated that the higher-order modes are more sensitive to uncertainty propagation in spatially varying properties.

关键词： composite plate spatially varying stochastic properties Galerkin method polynomial chaos approach semi-analytical approach

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亚奈奎斯特采样的数据恢复：性能极限与恢复算法

罗茜倩,张朝阳

《信息与电子工程前沿（英文）》 2021年第22卷第2期页码 141-286 doi: 10.1631/FITEE.1900320

摘要：奈奎斯特频率是一般带限信号进行无损采样的采样率下界，然而在某些情景中，亚奈奎斯特频率也足以进行无损采样和信号恢复。以往对亚奈奎斯特采样的研究主要集中在利用信号变换来降低信号维度，但是亚奈奎斯特采样信号的结构并没有得到充分研究。本文针对线性调制基带信号的亚奈奎斯特采样，研究其信号恢复性能极限与算法。该问题中，原信号维度无法降低，因此亚奈奎斯特采样不可避免会带来信息损失，信号恢复也变成一个欠定线性问题。本文采用两种亚奈奎斯特采样方法对线性调制基带信号进行采样，分别研究了两种采样方法下的性能极限和信号恢复算法。首先，针对两种亚奈奎斯特采样方法，分别计算了采样序列之间的最小归一化欧氏距离，以此作为最优性能的指标。然后，在基带信号有限符号集的限制条件下，采用改进的时变维特比算法从亚奈奎斯特采样序列中恢复原信号。将仿真得到的亚奈奎斯特采样的误比特率与其性能的理论极限比较，并与奈奎斯特采样性能对比，验证了时变维特比算法在信号恢复问题中的优良性能。

关键词：奈奎斯特采样定理；亚奈奎斯特采样；最小欧式距离；欠定线性问题；时变维特比算法

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δN-stable isotope analysis of NH: An overview on analytical measurements, source sampling and its source

《环境科学与工程前沿（英文）》 2021年第15卷第6期 doi: 10.1007/s11783-021-1414-6

摘要：

• Challenges in sampling of NH₃ sources for d¹⁵N analysis are highlighted.

关键词： Aerosol ammonium Atmospheric gaseous ammonia Isotope fingerprinting Isotope-based source apportionment Ammonia gas-to-particle conversion

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A case study on sample average approximation method for stochastic supply chain network design problem

Yuan WANG, Ruyan SHOU, Loo Hay LEE, Ek Peng CHEW

《工程管理前沿（英文）》 2017年第4卷第3期页码 338-347 doi: 10.15302/J-FEM-2017032

摘要： This study aims to solve a typical long-term strategic decision problem on supply chain network design with consideration to uncertain demands. Existing methods for these problems are either deterministic or limited in scale. We analyze the impact of uncertainty on demand based on actual large data from industrial companies. Deterministic equivalent model with nonanticipativity constraints, branch-and-fix coordination, sample average approximation (SAA) with Bayesian bootstrap, and Latin hypercube sampling were adopted to analyze stochastic demands. A computational study of supply chain network with front-ends in Europe and back-ends in Asia is presented to highlight the importance of stochastic factors in these problems and the efficiency of our proposed solution approach.

关键词： supply chain network stochastic demand sampling average approximation Bayesian bootstrap Latin hypercube sampling

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基于重要性采样的TOA与FOA无源定位算法 Article

Rui-rui LIU, Yun-long WANG, Jie-xin YIN, Ding WANG, Ying WU

《信息与电子工程前沿（英文）》 2017年第18卷第8期页码 1167-1179 doi: 10.1631/FITEE.1601657

摘要：最大似然类的无源定位方法可以达到较高的定位精度，但其计算量非常大。由于时频参数联合定位模型本身的非线性和非凸性非常大，繁重的计算量在TOA与FOA联合定位系统中表现尤为明显。本文针对这一问题，通过Pincus全局最优理论和蒙特卡洛重要性采样技术降低了最大似然类定位算法的计算复杂度，并且保证算法可以收敛到全局最优解。本文主要的贡献是构建了一个高斯分布的概率密度函数来近似原始的代价函数方便后续的采样，我们称之为重要性函数。该方法所带来性能上的提升是因为选择了最优的重要性函数并且Pincus保证算法收敛到全局最小值。这一处理大大降低了计算量，由于算法进行了泰勒级数展开，需要初始估计值。通过采样处理并且对样本进行加权，本文算法对初始估计值具有良好的鲁棒性。最后，实验证明本文所提算法可以达到克拉美罗限，且性能要优于现有算法。

关键词：无源定位；到达时间；到达频率；蒙特卡洛重要性采样；最大似然估计

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基于异构特征和组合分类器的网页分类 Research Articles

邓立,杜歆,沈继忠

《信息与电子工程前沿（英文）》 2020年第21卷第7期页码 963-1118 doi: 10.1631/FITEE.1900240

摘要：网页特征是网页分类的关键，通过有区分度的特征能有效对网页分类。网页结构特征是对文本特征的有效补充。不同分类器有不同特点，多分类器组合可实现分类器性能互补。提出一种基于异构特征和组合分类器的网页分类算法。与计算HTML标记的频率不同，本文采用树状分布的HTML标签表示网页结构特征，以向量形式将异构文本和结构特征融合。通过计算一组样本的分类准确率，提出将分类结果置信度作为比较不同分类器分类结果的标准。基于置信度采用投票、比较大小和直接输出的决策策略，得到组合分类器的分类结果。实验结果表明，在Amazon数据集、7-web-genres数据集和DMOZ数据集中，准确率分别提高到94.2%、95.4%、95.7%。融合文本和结构特征的分类方法比仅使用文本特征的方法更全面有效。同时多分类器组合能够提高网页分类准确率，高于同类网页组合分类算法。

关键词：网页分类；网页特征；分类器组合

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Mercury source zone identification using soil vapor sampling and analysis

David WATSON,Carrie MILLER,Brian LESTER,Kenneth LOWE,George SOUTHWORTH,Mary Anna BOGLE,Liyuan LIANG,Eric PIERCE

《环境科学与工程前沿（英文）》 2015年第9卷第4期页码 596-604 doi: 10.1007/s11783-014-0709-2

摘要： Development and demonstration of reliable measurement techniques that can detect and help quantify the nature and extent of elemental mercury (Hg(0)) in the subsurface are needed to reduce uncertainties in the decision-making process and increase the effectiveness of remedial actions. We conducted field tests at the Y-12 National Security Complex in Oak Ridge, Tennessee, USA, to determine if sampling and analysis of Hg(0) vapors in the shallow subsurface (<0.3 m depth) can be used to as an indicator of the location and extent of Hg(0) releases in the subsurface. We constructed a rigid polyvinyl chloride push probe assembly, which was driven into the ground. Soil gas samples were collected through a sealed inner tube of the assembly and were analyzed immediately in the field with a Lumex and/or Jerome Hg(0) analyzer. Time-series sampling showed that Hg vapor concentrations were fairly stable over time, suggesting that the vapor phase Hg(0) was not being depleted and that sampling results were not sensitive to the soil gas purge volume. Hg(0) vapor data collected at over 200 push probe locations at 3 different release sites correlated very well to areas of known Hg(0) contamination. Vertical profiling of Hg(0) vapor concentrations conducted at two locations provided information on the vertical distribution of Hg(0) contamination in the subsurface. We conclude from our studies that soil gas sampling and analysis can be conducted rapidly and inexpensively at large scales to help identify areas contaminated with Hg(0).

关键词： push probe spill characterization mapping gas

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Classification of contaminants and treatability evaluation of domestic wastewater

WANG Xiaochang, JIN Pengkang, ZHAO Hongmei, MENG Lingba

《环境科学与工程前沿（英文）》 2007年第1卷第1期页码 57-62 doi: 10.1007/s11783-007-0011-7

摘要： Long-term sampling and analysis were conducted in a domestic wastewater treatment plant for the investigation on the characteristics of the representative contaminants in raw sewage such as SS, COD, BOD5, TP, and TN. All these constituents were classified into dissolved and suspended groups by using a 0.45-µm membrane filter, and the concentration of each constituent in each group was analyzed. As a result, almost 100% of the SS was found to be suspended matter, as well as about 65% of COD, 60% of BOD, 50% of P, and 20% of N. All these could be easily removed by sedimentation or coagulation/sedimentation. A treatability evaluation diagram was proposed for a rational selection of wastewater treatment process in accordance with raw water quality.

关键词： Long-term sampling selection accordance wastewater treatment coagulation/sedimentation