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selected semi-volatile organic compounds in water using automated online solid-phase extraction with large-volumeinjection/gas chromatography/mass spectrometry

Yongtao LI, Christina L. MCCARTY, Ed J. GEORGE

《环境科学与工程前沿（英文）》 2011年第5卷第3期页码 417-425 doi: 10.1007/s11783-011-0310-x

摘要： A rapid, sensitive, and cost-effective analytical method was developed for the analysis of selected semi-volatile organic compounds in water. The method used an automated online solid-phase extraction technique coupled with programmed-temperature vaporization large-volume injection gas chromatography/mass spectrometry. The water samples were extracted by using a fully automated mobile rack system based on x-y-z robotic techniques using syringes and disposable 96-well extraction plates. The method was validated for the analysis of 30 semi-volatile analytes in drinking water, groundwater, and surface water. For a sample volume of 10 mL, the linear calibrations ranged from 0.01 or 0.05 to 2.5μg·L , and the method detection limits were less than 0.1μg·L . For the reagent water samples fortified at 1.0μg·L and 2.0?μg·L , the obtained mean absolute recoveries were 70%–130% with relative standard deviations of less than 20% for most analytes. For the drinking water, groundwater, and surface water samples fortified at 1.0μg·L , the obtained mean absolute recoveries were 50%–130% with relative standard deviations of less than 20% for most analytes. The new method demonstrated three advantages: 1) no manipulation except the fortification of surrogate standards prior to extraction; 2) significant cost reduction associated with sample collection, shipping, storage, and preparation; and 3) reduced exposure to hazardous solvents and other chemicals. As a result, this new automated method can be used as an effective approach for screening and/or compliance monitoring of selected semi-volatile organic compounds in water.

关键词： automated solid-phase extraction programmed-temperature vaporization large-volume injection gas chromatography/mass spectrometry semi-volatile organic compounds water analysis

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Trend prediction technology of condition maintenance for large water injection units

Xiaoli XU, Sanpeng DENG

《机械工程前沿（英文）》 2010年第5卷第2期页码 171-175 doi: 10.1007/s11465-009-0091-0

摘要： Trend prediction technology is the key technology to achieve condition-based maintenance of mechanical equipment. Large-sized water injection units are key equipment in oilfields. The traditional preventive maintenance is not economical and cannot completely avoid vicious accidents. To ensure the normal operation of units and save maintenance costs, trend prediction technology is studied to achieve condition-based maintenance for water injection units. The main methods of the technology are given, the trend prediction method based on neural network is put forward, and the expert system based on the knowledge is developed. The industrial site verification shows that the proposed trend prediction technology can reflect the operating condition trend change of the water injection units and provide technical means to achieve condition-based predictive maintenance.

关键词： water injection units condition-based maintenance trend prediction

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Hélène Mainaud Durand：Advances in Large Volume Metrology in Particles Accelerators（2019年10月10日）

2021年04月23日

关键词：高性能制造

Shanghai Tower

Jian GONG

《工程管理前沿（英文）》 2017年第4卷第1期页码 106-109 doi: 10.15302/J-FEM-2017001

摘要： Ru-jiang Zhao,Wung Hee Moh. [J]. Front. Eng, 2016, 3(2): 147-157.

关键词： super-high-rise building green building integral steel platform formwork system large volume concrete concrete pumped for super-high building deep and large foundation pit combined anterograde and retrograde methods digitalized construction technology

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Molecular dynamics study of water diffusion in an amphiphilic block copolymer with large difference in

Yang Zhou, Phillip Choi

《化学科学与工程前沿（英文）》 2017年第11卷第3期页码 440-447 doi: 10.1007/s11705-017-1626-2

摘要： Isothermal-isobaric molecular dynamics simulation was used to study the diffusion mechanism of water in polyurethane- -poly( -isopropyl acrylamide) (PU- -PNIPAm) with a hydrophobic PU/hydrophilic PNIPAm mass ratio of 1.4 to 1 at 298 K and 450 K. Here, the experimental glass transition temperature ( ) of PU is 243 K while that of PNIPAm is 383 K. Different amounts of water up to 15 wt-% were added to PU- -PNIPAm. We were able to reproduce the specific volumes and glass transition temperatures (250 K and 390 K) of PU- -PNIPAm. The computed self-diffusion coefficient of water increased exponentially with increasing water concentration at both temperatures (i.e., following the free volume model of Fujita). It suggested that water diffusion in PU- -PNIPAm depends only on its fractional free volume despite the free volume inhomogeneity. It is noted that at 298 K, PU is rubbery while PNIPAm is glassy. Regardless of temperature, radial distribution functions showed that water formed clusters with sizes in the range of 0.2–0.4 nm in PU- -PNIPAm. At low water concentrations, more clusters were found in the PU domain but at high water concentrations, more in the PNIPAm domain. It is believed that water molecules diffuse as clusters rather than as individual molecules.

关键词： molecular dynamics simulation amphiphilic block copolymer free volume water diffusivity fujita model

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Pre-chamber turbulent jet ignition of methane/air mixtures with multiple orifices in a large bore constantvolume chamber: effect of air-fuel equivalence ratio and pre-mixed pressure

Xiang LI, Wenzheng ZHANG, Zhong HUANG, Dehao JU, Li HUANG, Mingzhi FENG, Xingcai LU, Zhen HUANG

《能源前沿（英文）》 2019年第13卷第3期页码 483-493 doi: 10.1007/s11708-019-0631-1

摘要： Liquefied natural gas (LNG), mainly composed of methane, is in progress to substitute diesel fuel in heavy-duty marine engine for practical, economic, and environmental considerations. However, natural gas is relatively difficult to be ignited in a large bore combustion chamber. A combustion enhancement technique called pre-chamber turbulent jet ignition (TJI) can permit combustion and flame propagation in a large-bore volume. To investigate the effect of air-fuel equivalence ratio and pre-mixed pressure on pre-chamber TJI of methane/air mixtures with multiple orifices in a large bore volume, experimental tests and computational simulations were implemented to study the discharge of hot turbulent jets from six orifices of the pre-chamber. Different initial pressures and air-fuel equivalence ratios were considered to analyze the characteristics of TJI. The asymmetry of the turbulent jet actuated from six different orifices were found due to the asymmetric orientation of the spark plug, resulting in the inhomogeneous distribution of combustion in the constant volume chamber, which should be considered seriously in the marine engine design. Besides, as the premixed pressure increases, it has more effect on the flame propagation and plays a more important role, as it further increases.

关键词： marine engine natural gas methane turbulent jet ignition (TJI) pre-chamber

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Assessment of liver volume variation to evaluate liver function

null

《医学前沿（英文）》 2012年第6卷第4期页码 421-427 doi: 10.1007/s11684-012-0223-5

摘要：

In order to assess the value of liver volumetry in cirrhosis and acute liver failure (ALF) patients, we explored the correlation between hepatic volume and severity of the hepatic diseases. The clinical data of 48 cirrhosis patients with 60 normal controls and 39 ALF patients were collected. Computed tomography-derived liver volume (CTLV) and body surface area (BSA) of normal controls were calculated to get a regression formula for standard liver volume (SLV) and BSA. Then CTLV and SLV of all patients were calculated and grouped by Child-Turcotte-Pugh classification for cirrhosis patients and assigned according to prognosis of ALF patients for further comparison. It turned out that the mean liver volume of the control group was 1 058±337 cm³. SLV was correlated with BSA according to the regression formula. The hepatic volume of cirrhosis patients in Child A, B level was not reduced, but in Child C level it was significantly reduced with the lowest liver volume index (CTLV/SLV). Likewise, in the death group of ALF patients, the volume index was significantly lower than that of the survival group. Based on volumetric study, we proposed an ROC (receiver operating characteristic) analysis to predict the prognosis of ALF patients that CTLV/SLV<83.9% indicates a poor prognosis. In conclusion, the CTLV/SLV ratio, which reflects liver volume variations, correlates well with the liver function and progression of cirrhosis and ALF. It is also a very useful marker for predicting the prognosis of ALF.

关键词： liver volume variation cirrhosis acute liver failure (ALF)

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我国低孔渗储层天然气资源大型化成藏特征与分布规律

赵文智,王红军,卞从胜,汪泽成,柳广弟

《中国工程科学》 2012年第14卷第6期页码 31-39

摘要：

低孔渗储层天然气资源是目前和未来一段时间我国天然气勘探和开发的主体，具有大型化成藏的特点。集中讨论了这类天然气资源大型化成藏的特征和分布规律，认识到成藏要素具有大型化发育与规模变化的特征，是天然气大型化成藏的基础；薄饼式、集群式成藏是天然气大型化成藏的主要样式；气源灶埋藏期规模“蓄能”和抬升期规模排气是大型化成藏重要气源输入；体积流和扩散流充注是天然气大型化成藏的主要运聚方式。低孔渗储层天然气藏的成藏分布具有近源性，成藏组合以大面积和大范围两种类型为主，成藏类型以地层—岩性圈闭为主，主要分布在海相克拉通盆地古隆起围斜区、陆内坳陷盆地广大斜坡区和向斜区以及前陆盆地缓翼斜坡等地区。低孔渗储层天然气资源大型化成藏认识的提出，提升了我国天然气资源发现潜力，扩展了勘探范围，为客观评价我国天然气主体资源总量和分布、推动有效发现大气田提供了理论基础。

关键词：低孔渗储层大型化成藏体积流扩散流薄饼式集群式

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Destructive and non-destructive evaluation of concrete for optimum sand to aggregate volume ratio

《结构与土木工程前沿（英文）》 2021年第15卷第6期页码 1400-1414 doi: 10.1007/s11709-021-0779-8

摘要： Aggregates are the biggest contributor to concrete volume and are a crucial parameter in dictating its mechanical properties. As such, a detailed experimental investigation was carried out to evaluate the effect of sand-to-aggregate volume ratio (s/a) on the mechanical properties of concrete utilizing both destructive and non-destructive testing (employing UPV (ultrasonic pulse velocity) measurements). For investigation, standard cylindrical concrete samples were made with different s/a (0.36, 0.40, 0.44, 0.48, 0.52, and 0.56), cement content (340 and 450 kg/m³), water-to-cement ratio (0.45 and 0.50), and maximum aggregate size (12 and 19 mm). The effect of these design parameters on the 7, 14, and 28 d compressive strength, tensile strength, elastic modulus, and UPV of concrete were assessed. The careful analysis demonstrates that aggregate proportions and size need to be optimized for formulating mix designs; optimum ratios of s/a were found to be 0.40 and 0.44 for the maximum aggregate size of 12 and 19 mm, respectively, irrespective of the W/C (water-to-cement) and cement content.

关键词： aggregates non-destructive testing sand-to-aggregate volume ratio (s/a) maximum aggregate size (MAS)

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Three-dimensional numerical simulation for plastic injection-compression molding

Yun ZHANG, Wenjie YU, Junjie LIANG, Jianlin LANG, Dequn LI

《机械工程前沿（英文）》 2018年第13卷第1期页码 74-84 doi: 10.1007/s11465-018-0490-1

摘要：

Compared with conventional injection molding, injection-compression molding can mold optical parts with higher precision and lower flow residual stress. However, the melt flow process in a closed cavity becomes more complex because of the moving cavity boundary during compression and the nonlinear problems caused by non-Newtonian polymer melt. In this study, a 3D simulation method was developed for injection-compression molding. In this method, arbitrary Lagrangian-Eulerian was introduced to model the moving-boundary flow problem in the compression stage. The non-Newtonian characteristics and compressibility of the polymer melt were considered. The melt flow and pressure distribution in the cavity were investigated by using the proposed simulation method and compared with those of injection molding. Results reveal that the fountain flow effect becomes significant when the cavity thickness increases during compression. The back flow also plays an important role in the flow pattern and redistribution of cavity pressure. The discrepancy in pressures at different points along the flow path is complicated rather than monotonically decreased in injection molding.

关键词： injection-compression molding simulation injection molding melt flow cavity pressure

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density measurement for plastic injection molding via ultrasonic technology

《机械工程前沿（英文）》 2022年第17卷第4期 doi: 10.1007/s11465-022-0714-2

摘要： Density variation during the injection molding process directly reflects the state of plastic melt and contains valuable information for process monitoring and optimization. Therefore, in-situ density measurement is of great interest and has significant application value. The existing methods, such as pressure−volume−temperature (PVT) method, have the shortages of time-delay and high cost of sensors. This study is the first to propose an in-situ density measurement method using ultrasonic technology. The analyses of the time-domain and frequency-domain signals are combined in the proposed method. The ultrasonic velocity is obtained from the time-domain signals, and the acoustic impedance is computed through a full-spectral analysis of the frequency-domain signals. Experiments with different process conditions are conducted, including different melt temperature, injection speed, material, and mold structure. Results show that the proposed method has good agreement with the PVT method. The proposed method has the advantages of in-situ measurement, non-destructive, high accuracy, low cost, and is of great application value for the injection molding industry.

关键词： ultrasonic measurement melt density in-situ measurement injection molding

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凝析气藏的经济开采模式

刘廷元

《中国工程科学》 2001年第3卷第3期页码 85-91

摘要：

液态凝析油是凝析气藏的重要产品，它的开采应该是有效而经济的。介绍了国外近20 a来在凝析气藏开采技术领域的各种经济模式，包括回注φ_d=75%干气、自流回注、注N₂、注水、水气交替注和注CO₂等开采模式。研究结果表明，这些开采模式同传统的降压开采方法相比，能够有效地适应地面-地下的各种复杂情况。

关键词：凝析气藏开采模式注气注氮注水注二氧化碳经济

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Intelligent methods for the process parameter determination of plastic injection molding

Huang GAO, Yun ZHANG, Xundao ZHOU, Dequn LI

《机械工程前沿（英文）》 2018年第13卷第1期页码 85-95 doi: 10.1007/s11465-018-0491-0

摘要：

Injection molding is one of the most widely used material processing methods in producing plastic products with complex geometries and high precision. The determination of process parameters is important in obtaining qualified products and maintaining product quality. This article reviews the recent studies and developments of the intelligent methods applied in the process parameter determination of injection molding. These intelligent methods are classified into three categories: Case-based reasoning methods, expert system-based methods, and data fitting and optimization methods. A framework of process parameter determination is proposed after comprehensive discussions. Finally, the conclusions and future research topics are discussed.

关键词： injection molding intelligent methods process parameters optimization

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Integration of molecular dynamic simulation and free volume theory for modeling membrane VOC/gas separation

Bo Chen, Yan Dai, Xuehua Ruan, Yuan Xi, Gaohong He

《化学科学与工程前沿（英文）》 2018年第12卷第2期页码 296-305 doi: 10.1007/s11705-018-1701-3

摘要： Gas membrane separation process is highly unpredictable due to interacting non-ideal factors, such as composition/pressure-dependent permeabilities and real gas behavior. Although molecular dynamic (MD) simulation can mimic those complex effects, it cannot precisely predict bulk properties due to scale limitations of calculation algorithm. This work proposes a method for modeling a membrane separation process for volatile organic compounds by combining the MD simulation with the free volume theory. This method can avoid the scale-up problems of the MD method and accurately simulate the performance of membranes. Small scale MD simulation and pure gas permeation data are employed to correlate pressure-irrelevant parameters for the free volume theory; by this approach, the microscopic effects can be directly linked to bulk properties (non-ideal permeability), instead of being fitted by a statistical approach. A lab-scale hollow fiber membrane module was prepared for the model validation and evaluation. The comparison of model predictions with experimental results shows that the deviations of product purity are reduced from 10% to less than 1%, and the deviations of the permeate and residue flow rates are significantly reduced from 40% to 4%, indicating the reliability of the model. The proposed method provides an efficient tool for process engineering to simulate the membrane recovery process.

关键词： membrane vapor separation membrane process modeling process engineering free volume theory volatile organic compound

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methodology for regulating fuel stratification and improving fuel economy of GCI mode via double main-injection

《能源前沿（英文）》 2023年第17卷第5期页码 678-691 doi: 10.1007/s11708-022-0859-z

摘要： Gasoline compression ignition (GCI) combustion faces problems such as high maximum pressure rise rate (MPRR) and combustion deterioration at high loads. This paper aims to improve the engine performance of the GCI mode by regulating concentration stratification and promoting fuel-gas mixing by utilizing the double main-injection (DMI) strategy. Two direct injectors simultaneously injected gasoline with an octane number of 82.7 to investigate the energy ratio between the two main-injection and exhaust gas recirculation (EGR) on combustion and emissions. High-load experiments were conducted using the DMI strategy and compared with the single main-injection (SMI) strategy and conventional diesel combustion. The results indicate that the DMI strategy have a great potential to reduce the MPRR and improve the fuel economy of the GCI mode. At a 10 bar indicated mean effective pressure, increasing the main-injection-2 ratio (R_m-2) shortens the injection duration and increases the mean mixing time. Optimized R_m-2 could moderate the trade-off between the MPRR and the indicated specific fuel consumption with both reductions. An appropriate EGR should be adopted considering combustion and emissions. The DMI strategy achieves a highly efficient and stable combustion at high loads, with an indicated thermal efficiency (ITE) greater than 48%, CO and THC emissions at low levels, and MPRR within a reasonable range. Compared with the SMI strategy, the maximum improvement of the ITE is 1.5%, and the maximum reduction of MPRR is 1.5 bar/°CA.

关键词： gasoline compression ignition injection strategy fuel stratification high efficiency high load

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标题作者时间类型操作

selected semi-volatile organic compounds in water using automated online solid-phase extraction with large-volumeinjection/gas chromatography/mass spectrometry

Yongtao LI, Christina L. MCCARTY, Ed J. GEORGE

期刊论文

Trend prediction technology of condition maintenance for large water injection units

Xiaoli XU, Sanpeng DENG

期刊论文

Hélène Mainaud Durand：Advances in Large Volume Metrology in Particles Accelerators（2019年10月10日）

2021年04月23日

会议视频

Shanghai Tower

Jian GONG

期刊论文

Molecular dynamics study of water diffusion in an amphiphilic block copolymer with large difference in

Yang Zhou, Phillip Choi

期刊论文

Pre-chamber turbulent jet ignition of methane/air mixtures with multiple orifices in a large bore constantvolume chamber: effect of air-fuel equivalence ratio and pre-mixed pressure

Xiang LI, Wenzheng ZHANG, Zhong HUANG, Dehao JU, Li HUANG, Mingzhi FENG, Xingcai LU, Zhen HUANG

期刊论文

Assessment of liver volume variation to evaluate liver function

null

期刊论文

我国低孔渗储层天然气资源大型化成藏特征与分布规律

赵文智,王红军,卞从胜,汪泽成,柳广弟

期刊论文

Destructive and non-destructive evaluation of concrete for optimum sand to aggregate volume ratio

期刊论文

Three-dimensional numerical simulation for plastic injection-compression molding

Yun ZHANG, Wenjie YU, Junjie LIANG, Jianlin LANG, Dequn LI