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Synthesis of novel magneto-hybrid polyoxometalate composite membrane with simultaneous photocatalytic self-cleaning

《化学科学与工程前沿(英文)》 2023年 第17卷 第10期   页码 1450-1459 doi: 10.1007/s11705-023-2310-3

摘要: Membrane technology is ideal for removing aqueous humic acid, but humic acid deposits cause membrane fouling, a significant challenge that limits its application. Herein, this work proposed an alternative approach to the controllably magnetically induced magneto-hybrid polyoxometalate (magneto-HPOM) nanocomposite migration toward the polyethersulfone (PES) membrane surface under a magnetic field to enhance the self-cleaning and antifouling functionalities of the membrane. Before incorporating magneto-HPOM nanocomposite into the PES casting solution, functionalized magnetite nanoparticles (F-MNP) were first coated with HPOM photocatalyst to fabricate a magneto-HPOM-PES membrane. It was shown that the apparent impacts of this novel magneto-HPOM-PES membrane on the hydrophilic behavior and photocatalytic properties of the magneto-HPOM nanocomposite improve the hydrophilicity, separation performance, antifouling and self-cleaning properties of the membrane compared with neat PES membrane. Furthermore, after exposure to ultraviolet light, the magneto-HPOM-PES membrane can be recovered after three cycles with a flux recovery ratio of 107.95%, 100.06%, and 95.56%, which is attributed to the temporal super hydrophilicity effect. Meanwhile, the magneto-HPOM-PES membrane could efficiently maintain 100% humic acid rejection for the first and second cycles and 99.81% for the third cycle. This study revealed a novel approach to fabricating membranes with high antifouling and self-cleaning properties for water treatment.

关键词: magneto-hybrid polyoxometalate nanocomposite     composite membrane     antifouling     self-cleaning     magnetic and photocatalytic responsiveness    

Experimental investigation of multiphase flow behavior in drilling annuli using high speed visualization technique

Alap Ali ZAHID, Syed Raza ur REHMAN, Anwarul HASAN, S. RUSHD, Mohammad Azizur RAHMAN

《能源前沿(英文)》 2020年 第14卷 第3期   页码 635-643 doi: 10.1007/s11708-018-0582-y

摘要: Imaging with high definition video camera is an important technique to visualize the drilling conditions and to study the physics of complex multiphase flow associated with the hole cleaning process. The main advantage of visualizing multiphase flow in a drilling annulus is that the viewer can easily distinguish fluid phases, flow patterns and thicknesses of cutting beds. In this paper the hole cleaning process which involves the transportation of cuttings through a horizontal annulus was studied. The two-phase (solid-liquid) and the three-phase (solid-liquid-gas) flow conditions involved in this kind of annular transportation were experimentally simulated and images were taken using a high definition camera. Analyzing the captured images, a number of important parameters like velocities of different phases, heights of solid beds and sizes of gas bubbles were determined. Two different techniques based on an image analysis software and MATLAB coding were used for the determinations. The results were compared to validate the image analyzing methodology. The visualization technique developed in this paper has a direct application in investigating the critical conditions required for efficient hole cleaning as well as in optimizing the mud program during both planning and operational phases of drilling. Particularly, it would be useful in predicting the cuttings transport performance, estimating solid bed height, gas bubble size, and mean velocities of bubbles/particles.

关键词: visualization     horizontal annulus     hole cleaning     multiphase flow     image analysis     flow regime    

Improving hole transfer of boron nitride quantum dots modified PDI for efficient photodegradation

《化学科学与工程前沿(英文)》 2023年 第17卷 第11期   页码 1718-1727 doi: 10.1007/s11705-023-2319-7

摘要: In recent years, organic photocatalyst under visible-light absorption has shown significant potential for solving environmental problems. However, it is still a great challenge for constructing a highly active organic photocatalyst due to the low separation efficiency of photogenerated carriers. Herein, an effective and robust photocatalyst perylene-3,4,9,10-tetracarboxylic diamide/boron nitride quantum dots (PDI/BNQDs), consisting of self-assemble PDI with π–π stacking structure and BNQDs, has been constructed and researched under visible light irradiation. The PDI/BNQDs composite gradually increases organic pollutant photodegradation with the loading amount of BNQDs. With 10 mL of BNQDs solution added (PDI/BNQDs-10), the organic pollutant photodegradation performance reaches a maximum, about 6.16 times higher with methylene blue and 1.68 times higher with ciprofloxacin than that of pure PDI supramolecular. The enhancement is attributed to improved separation of photogenerated carriers from self-assembled PDI by BNQDs due to their preeminent ability to extract holes. This work is significant for the supplement of PDI supramolecular composite materials. We believe that this photocatalytic design is capable of expanding organic semiconductors’ potential for their applications in photocatalysis.

关键词: PDI     boron nitride     quantum dots     photocatalysis     hole transfer    

Formation of disinfection by-products during sodium hypochlorite cleaning of fouled membranes from membrane

《环境科学与工程前沿(英文)》 2021年 第15卷 第5期 doi: 10.1007/s11783-021-1389-3

摘要:

•HAAs was dominant among the DBPs of interest.

关键词: MBR     Biofouling     EPS     Chemical cleaning     DBPs     CLSM    

Fracture behavior of two non-symmetrical collinear cracks emanating from an elliptical hole in a piezoelectric

Junhong GUO, Zixing LU

《机械工程前沿(英文)》 2011年 第6卷 第3期   页码 296-300 doi: 10.1007/s11465-011-0236-9

摘要:

Based on the Stroh-type formalism and the technique of conformal mapping, the problem of two non-symmetrical collinear cracks emanating from an elliptical hole in a piezoelectric solid is investigated under remotely uniform in-plane electric loading and anti-plane mechanical loading, which allowed us to take the electric field inside the hole and cracks into account. The analytical solutions of the field intensity factors and the energy release rate are presented in closed-form, which includes the extreme cases for an impermeable crack and a permeable crack. Numerical results are then presented to reveal the effects of geometrical parameters, crack permeability and combined mechanical and electric loadings on the energy release rate.

关键词: piezoelectric materials     elliptical hole     semi-permeable crack     energy release rate     analytic solution    

The influence of hand hole on the ultimate strength and crack pattern of shield tunnel segment joints

Shaochun WANG, Xi JIANG, Yun BAI

《结构与土木工程前沿(英文)》 2019年 第13卷 第5期   页码 1200-1213 doi: 10.1007/s11709-019-0546-2

摘要: With the shield tunnel going deeper and deeper, the circumferential axial force becomes the governing factor rather than the bending moment. The hand hole acts as a weak point and initial damage in the segment joint especially when the circumferential axial force is extremely high. Despite the wide application of steel fiber or synthetic fiber in the tunneling, limited researches focus on the structural responses of segment joint with macro structural synthetic fiber (MSSF). In this paper, a 1:2 reduced-scale experiment was conducted to study the structural performance of the segment joint with different types of hand holes under ultra-high axial force. Special attention is paid to failure mode and structural performance (bearing capacity, deformation, cracking, and toughness). Moreover, segment joints with MSSF are also tested to evaluate the effects of MSSF on the failure mode and structural performance of the segment joints. The experiment results show that the hand hole becomes the weakest point of the segment joint under ultra-high axial force. A \ /-type crack pattern is always observed before the final failure of the segment joints. Different types and sizes of the hand hole have different degree of influences on the structural behavior of segment joints. The segment joint with MSSF shows higher ultimate bearing capacity and toughness compared to segment joint with common concrete. Besides, the MSSF improves the initial cracking load and anti-spallling resistance of the segment joint.

关键词: shield tunneling     structural synthetic fiber concrete     hand hole     segment joint     ultimate bearing capacity     crack pattern    

characteristic evaluation and interpolation reconstruction for surface topography of drilled composite hole

《机械工程前沿(英文)》 2021年 第16卷 第4期   页码 840-854 doi: 10.1007/s11465-021-0643-5

摘要: In this paper, an improved fractal interpolation model is proposed to reconstruct the surface topography of composite hole wall. This model adopts the maximum positive deviations and maximum negative deviations between the measured values and trend values to determine the contraction factors. Hole profiles in 24 directions are measured. Fractal parameters are calculated to evaluate the measured surface profiles. The maximum and minimum fractal dimension of the hole wall are 1.36 and 1.07, whereas the maximum and minimum fractal roughness are 4.05 × 10 −5 and 4.36 × 10 −10 m, respectively. Based on the two-dimensional evaluation results, three-dimensional surface topographies in five typical angles (0°, 45°, 90°, 135°, and 165°) are reconstructed using the improved model. Fractal parameter D s and statistical parameters Sa, Sq, and Sz are used to evaluate the reconstructed surfaces. Average error of D s, Sa, Sq, and Sz between the measured surfaces and the reconstructed surfaces are 1.53%, 3.60%, 5.60%, and 9.47%, respectively. Compared with the model in published literature, the proposed model has equal reconstruction effect in relatively smooth surface and is more advanced in relatively rough surface. Comparative results prove that the proposed model for calculating contraction factors is more reasonable.

关键词: surface topography     fractal evaluation     fractal interpolation     reconstruction     composite    

气体分布板开孔结构对流化干燥滞留率的影响

刘巍,汤文成

《中国工程科学》 2006年 第8卷 第6期   页码 41-43

摘要:

滞留率是确定流化干燥死床点的重要参数。针对气体分布板开直孔和开斜孔的惰性粒子流化床干燥器,以洗衣粉悬浮液为对象,考查了进料量、惰性粒子直径、进风温度、静床高、进风速度以及物料初始浓度对干燥器滞留率的影响,分析了气体分布板开直孔和开斜孔时干燥器滞留率的大小,并以气体分布板开斜孔为例,测定了干燥器的生产能力与板开孔率之间的关系曲线。结果表明,滞留率随进料量和物料初始浓度的提高而增大,随惰性粒子直径、进风温度、静床高和进风速度的提高而减小;若将气体分布板的孔道由直孔改为斜孔,并在此基础上适当增加板的开孔率,可有效降低干燥器的滞留率,提高干燥器的生产能力。

关键词: 惰性粒子     流化干燥     气体分布板     开孔形状     开孔率     滞留率    

一种新型的多功能油——清洁润滑防护武器三用油

冯薇荪,汪孟言

《中国工程科学》 2000年 第2卷 第4期   页码 53-58

摘要:

武器三用油是一种不同于传统润滑油的油品。它不仅功能多,而且性能优异,可供陆、海、空三军在各种不同气候条件下使用;也可以广泛用于车辆、船舶、工厂、建筑物等民用设施。由于一种油品同时要具备多种功能,因此必需精心设计配方,考虑不同基础油及各种添加剂的配伍性,扬长避短,发挥增效作用,避免不利因素。在三用油研制过程中,考察了各种影响因素,将矛盾的各个方面很好地统一在一个油品中,获得了能满足各项要求的清洁、润滑、防护武器三用油。

关键词: 武器三用油     基础油     添加剂     清洁     润滑     防护    

A thermodynamic study of the removal of HCl and H

Joseph LEE, Bo FENG

《化学科学与工程前沿(英文)》 2012年 第6卷 第1期   页码 67-83 doi: 10.1007/s11705-011-1162-4

摘要: Advanced integrated-gasification combined-cycle (IGCC) and integrated-gasification fuel cell (IFGC) systems require high-temperature sorbents that are capable of removing hydrogen chloride and hydrogen sulfide from coal derived gases to very low levels. HCl and H S are highly reactive, corrosive, and toxic gases that must be removed to meet stringent environmental regulations, to protect power generation equipment and to control the emissions of contaminants. The thermodynamic behavior of 13 sorbents for the removal of HCl and H S under various conditions including: initial toxic gas concentration (1–10000 ppm), operating pressure (0.1–11 Mpa), temperature (300 K–1500 K), and the presence of H O were investigated. The correlation between HCl and H S was also examined. Thermodynamic calculations were carried out for the reactions of the 13 sorbents using a FactSage 5.2 software package based on free energy minimization. The sorbents, Na CO , NaHCO , K CO , and CaO are capable of completely removing chlorine at high temperatures (up to ~1240 K) and at high pressures. Water vapor did not have any significant effects on the dechlorination capability of the sorbents. Nine of the sorbents namely; Cu O, Na CO , NaHCO , K CO , CaO, ZnO, MnO, FeO, and PbO, were determined to have great potential as desulfurization sorbents. Cu O and ZnO had the best performance in terms of the optimum operating temperature. The addition of water vapor to the reactant gas produces a slightly detrimental effect on most of the sorbents, but FeO exhibited the worst performance with a reduction in the maximum operating temperature of about 428 K. The dechlorination performance of the alkali sorbents was not affected by the presence of H S in the reactions. However, the desulfurization capability of some sorbents was greatly affected by the presence of HCl. Particularly, the performance of Cu O was significantly reduced when HCl was present, but the performance of FeO improved remarkably. The thermodynamic results gathered are valuable for the developments of better sorbents.

关键词: syngas cleaning     sorbent     desulfurization     dechlorination    

Hole quality in longitudinal–torsional coupled ultrasonic vibration assisted drilling of carbon fiber

Guofeng MA, Renke KANG, Zhigang DONG, Sen YIN, Yan BAO, Dongming GUO

《机械工程前沿(英文)》 2020年 第15卷 第4期   页码 538-546 doi: 10.1007/s11465-020-0598-y

摘要: Carbon fiber reinforced plastic (CFRP) composites are extremely attractive in the manufacturing of structural and functional components in the aircraft manufacturing field due to their outstanding properties, such as good fatigue resistance, high specific stiffness/strength, and good shock absorption. However, because of their inherent anisotropy, low interlamination strength, and abrasive characteristics, CFRP composites are considered difficult-to-cut materials and are prone to generating serious hole defects, such as delamination, tearing, and burrs. The advanced longitudinal–torsional coupled ultrasonic vibration assisted drilling (LTC-UAD) method has a potential application for drilling CFRP composites. At present, LTC-UAD is mainly adopted for drilling metal materials and rarely for CFRP. Therefore, this study analyzes the kinematic characteristics and the influence of feed rate on the drilling performance of LTC-UAD. Experimental results indicate that LTC-UAD can reduce the thrust force by 39% compared to conventional drilling. Furthermore, LTC-UAD can decrease the delamination and burr factors and improve the surface quality of the hole wall. Thus, LTC-UAD is an applicable process method for drilling components made with CFRP composites.

关键词: longitudinal–torsional coupled     ultrasonically drilling     CFRP     thrust force     hole quality    

Using loose nanofiltration membrane for lake water treatment: A pilot study

《环境科学与工程前沿(英文)》 2021年 第15卷 第4期 doi: 10.1007/s11783-020-1362-6

摘要:

• A pilot study was conducted for drinking water treatment using loose NF membranes.

关键词: Nanofiltration     Drinking water     Membrane fouling     Aluminum carryover     Chemical cleaning    

地铁隧道爆破施工下穿地表建筑物的减振技术研究

方俊波

《中国工程科学》 2014年 第16卷 第11期   页码 58-64

摘要:

城市地铁区间隧道爆破施工中面临的一个重要问题就是降低爆破振动对临近地表建筑物的影 响。青岛地铁一期工程03号线03标段下穿建筑物时,为了确保距隧道拱顶5~8 m的地表建筑物安全,采 用了大中空孔直眼掏槽技术、一次起爆分部延时爆破、浅孔多眼等技术,将地表建筑物最大垂直振速控制 在国标允许范围之内,隧道通过后地表建筑物完好无损。并在施工中解决了大断面隧道爆破施工导爆管 雷管段数不能满足施工要求、分断面施工不能同时实施爆破作业,施工效率低下的问题,既保证了工程施 工安全又满足了进度要求。

关键词: 爆破设计     直眼掏槽     大直径中空孔     分部延时起爆     浅孔爆破    

气体分布板开孔结构对流化床干燥性能的影响

刘巍,汤文成

《中国工程科学》 2006年 第8卷 第2期   页码 47-50

摘要:

针对惰性粒子流化床干燥器,以洗衣粉悬浮液为对象,先后进行了气体分布板开直孔和开斜孔的流化干燥实验。通过测定干燥器的流体力学特性曲线,以及在相同进料量、进风温度、进风速度或惰性粒子直径条件下的体积传热系数曲线和热效率曲线,考察和分析了气体分布板两种不同的开孔结构对干燥器流体力学和传热性能的影响。结果表明,气体分布板开斜孔的床内气流阻力要高于开直孔的气流阻力,但其体积传热系数和热效率相对较高,即斜孔较直孔更加有利于床内传热。在此基础上,对惰性粒子流化床干燥器的生产调节措施进行了初步探讨。

关键词: 气体分布板     开孔结构     惰性粒子     流化床     干燥性能    

Probabilistic analysis of secant piles with random geometric imperfections

《结构与土木工程前沿(英文)》 2021年 第15卷 第3期   页码 682-695 doi: 10.1007/s11709-021-0703-2

摘要: The failure to achieve minimum design overlap between secant piles compromises the ability of a structure to perform as designed, resulting in water leakage or even ground collapse. To establish a more realistic simulation and provide guidelines for designing a safe and cost-effective secant-pile wall, a three-dimensional model of a secant pile, considering the geometric imperfections of the diameter and direction of the borehole, is introduced. An ultrasonic cross-hole test was performed during the construction of secant piles in a launching shaft in Beijing, China. Based on the test results, the statistical characteristics of the pile diameters and orientation parameters were obtained. By taking the pile diameter D, inclination angle β, and azimuth angle α as random variables, Monte Carlo simulations were performed to discuss the influence of different design parameters on the probability density functions of the overlap of secant piles. The obtained results show that the randomness of the inclination angle and pile diameter can be well described by a normal distribution, whereas the azimuth angle is more consistent with a uniform distribution. The integrity of the secant-pile wall can be overestimated without considering the uncertainty of geometric imperfections. The failure of the secant-pile wall increases substantially with increasing spatial variability in drilling inclination and diameter. A design flowchart for pile spacing under the target safety level is proposed to help engineers design a safe and economical pile wall.

关键词: secant piles     ultrasonic cross-hole testing     probabilistic analysis     reliability-based design     random imperfections    

标题 作者 时间 类型 操作

Synthesis of novel magneto-hybrid polyoxometalate composite membrane with simultaneous photocatalytic self-cleaning

期刊论文

Experimental investigation of multiphase flow behavior in drilling annuli using high speed visualization technique

Alap Ali ZAHID, Syed Raza ur REHMAN, Anwarul HASAN, S. RUSHD, Mohammad Azizur RAHMAN

期刊论文

Improving hole transfer of boron nitride quantum dots modified PDI for efficient photodegradation

期刊论文

Formation of disinfection by-products during sodium hypochlorite cleaning of fouled membranes from membrane

期刊论文

Fracture behavior of two non-symmetrical collinear cracks emanating from an elliptical hole in a piezoelectric

Junhong GUO, Zixing LU

期刊论文

The influence of hand hole on the ultimate strength and crack pattern of shield tunnel segment joints

Shaochun WANG, Xi JIANG, Yun BAI

期刊论文

characteristic evaluation and interpolation reconstruction for surface topography of drilled composite hole

期刊论文

气体分布板开孔结构对流化干燥滞留率的影响

刘巍,汤文成

期刊论文

一种新型的多功能油——清洁润滑防护武器三用油

冯薇荪,汪孟言

期刊论文

A thermodynamic study of the removal of HCl and H

Joseph LEE, Bo FENG

期刊论文

Hole quality in longitudinal–torsional coupled ultrasonic vibration assisted drilling of carbon fiber

Guofeng MA, Renke KANG, Zhigang DONG, Sen YIN, Yan BAO, Dongming GUO

期刊论文

Using loose nanofiltration membrane for lake water treatment: A pilot study

期刊论文

地铁隧道爆破施工下穿地表建筑物的减振技术研究

方俊波

期刊论文

气体分布板开孔结构对流化床干燥性能的影响

刘巍,汤文成

期刊论文

Probabilistic analysis of secant piles with random geometric imperfections

期刊论文