资源类型

期刊论文 240

年份

2023 22

2022 16

2021 18

2020 17

2019 11

2018 14

2017 12

2016 8

2015 6

2014 9

2013 10

2012 12

2011 7

2010 13

2009 15

2008 17

2007 10

2006 4

2005 1

2004 1

展开 ︾

关键词

悬索桥 3

渤海海峡 3

COVID-19 2

压力容器技术 2

压裂 2

惰性粒子 2

无损检测 2

跨海工程 2

ACE格式 1

ANSYS/LS-DYNA 1

AT89S52芯片 1

BOT 1

CRD法 1

DS1642芯片 1

ENDF/B VII.0评价库 1

LMS 1

MCNP 1

NJOY 1

PCR核酸检测 1

展开 ︾

检索范围：

排序： 展示方式：

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    

HTML PDF 收藏

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    

HTML PDF 收藏

硐室加深孔预裂爆破振动测试分析

申振宇,汪旭光,于亚伦,刘宏刚

《中国工程科学》 2006年 第8卷 第3期   页码 70-74

摘要：

硐室加深孔预裂爆破能够显著地降低硐室爆破所带来的地震效应，有效地解决爆破振动所造成的边坡稳定性、边坡质量和爆区附近建（构）筑物的安全问题，适用范围比较大。太原—长治高速公路硐室加深孔预裂爆破的振动测试获得明显的降震效果，对同类工程具有参考价值。

关键词： 硐室爆破     深孔预裂爆破     爆破振动     振动测试分析    

HTML PDF 收藏

A review of nondestructive examination technology for polyethylene pipe in nuclear power plant

Jinyang ZHENG, Yue ZHANG, Dongsheng HOU, Yinkang QIN, Weican GUO, Chuck ZHANG, Jianfeng SHI

《机械工程前沿（英文）》 2018年 第13卷 第4期   页码 535-545 doi: 10.1007/s11465-018-0515-9

摘要：

Polyethylene (PE) pipe, particularly high-density polyethylene (HDPE) pipe, has been successfully utilized to transport cooling water for both non-safety- and safety-related applications in nuclear power plant (NPP). Though ASME Code Case N755, which is the first code case related to NPP HDPE pipe, requires a thorough nondestructive examination (NDE) of HDPE joints. However, no executable regulations presently exist because of the lack of a feasible NDE technique for HDPE pipe in NPP. This work presents a review of current developments in NDE technology for both HDPE pipe in NPP with a diameter of less than 400 mm and that of a larger size. For the former category, phased array ultrasonic technique is proven effective for inspecting typical defects in HDPE pipe, and is thus used in Chinese national standards GB/T 29460 and GB/T 29461. A defect-recognition technique is developed based on pattern recognition, and a safety assessment principle is summa-rized from the database of destructive testing. On the other hand, recent research and practical studies reveal that in current ultrasonic-inspection technology, the absence of effective ultrasonic inspection for large size was lack of consideration of the viscoelasticity effect of PE on acoustic wave propagation in current ultrasonic inspection techno-logy. Furthermore, main technical problems were analyzed in the paper to achieve an effective ultrasonic test method in accordance to the safety and efficiency requirements of related regulations and standards. Finally, the development trend and challenges of NDE test technology for HDPE in NPP are discussed.

关键词： polyethylene pipe     nuclear power plant     ultrasonic inspection     nondestructive testing     safety assessment    

HTML PDF 收藏

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    

HTML PDF 收藏

Progress in terahertz nondestructive testing: A review

Shuncong ZHONG

《机械工程前沿（英文）》 2019年 第14卷 第3期   页码 273-281 doi: 10.1007/s11465-018-0495-9

摘要： Terahertz (THz) waves, whose frequencies range between microwave and infrared, are part of the electromagnetic spectrum. A gap exists in THz literature because investigating THz waves is difficult due to the weak characteristics of the waves and the lack of suitable THz sources and detectors. Recently, THz nondestructive testing (NDT) technology has become an interesting topic. This review outlines several typical THz devices and systems and engineering applications of THz NDT techniques in composite materials, thermal barrier coatings, car paint films, marine protective coatings, and pharmaceutical tablet coatings. THz imaging has higher resolution but lower penetration than ultrasound imaging. This review presents the significance and advantages provided by the emerging THz NDT technique.

关键词： terahertz pulsed imaging (TPI)     nondestructive testing (NDT)     composite material     thermal barrier coating    

HTML PDF 收藏

Testing of tuberculosis infection among Chinese adolescents born after terminating the Bacillus Calmette--Guérin booster vaccination: subgroup analysis of a population-based cross-sectional study

null

《医学前沿（英文）》 2017年 第11卷 第4期   页码 528-535 doi: 10.1007/s11684-017-0573-0

摘要：

The prevalence of tuberculosis infection among adolescents born after terminating the Bacillus Calmette–Guérin (BCG) booster vaccination in China was estimated using tuberculin skin testing (TST) and QuantiFERON-TB Gold assay (QFT) to investigate the influence of neonatal BCG vaccination on the performance of TST. Data analysis was conducted for 2831 eligible participants aged 5–15 years from the baseline survey of a population-based multi-center prospective study. The prevalence rates of TST (induration≥10 mm) and QFT positivity were 9.3% (264/2827) and 2.5% (71/2831), respectively. The rate of QFT indeterminate result was 2.2% (62/2831). The overall agreement between TST and QFT was low (concordance= 88.0%; κ coefficient= 0.125). Only TST was positively associated with BCG vaccination with an adjusted odds ratio of 1.71 [95% confidence interval, 1.26–2.31]. A history of close contact with patients of active TB was significantly associated with positivity for TST and QFT. Our results suggested that BCG neonatal vaccination still affects TST performance, and a two-step approach might be considered for TB infection testing among adolescents in China.

关键词： tuberculin skin test     interferon-γ release assays     adolescent     agreement    

HTML PDF 收藏

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    

HTML PDF 收藏

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    

HTML PDF 收藏

Linear ultrasonic motor using quadrate plate transducer

Jiamei JIN, Chunsheng ZHAO

《机械工程前沿（英文）》 2009年 第4卷 第1期   页码 88-91 doi: 10.1007/s11465-009-0016-y

摘要： A linear ultrasonic motor using a quadrate plate transducer was developed for precision positioning. This motor consists of two pairs of Pb(Zr,Ti)O piezoelectric ceramic elements, which are piezoelectrically excited into the second-bending mode of the motor stator’s neutral surface in two orthogonal directions, on which the tops of four projections move along an elliptical trajectory, which in turn drives a contacted slider into linear motion via frictional forces. The coincident frequency of the stator is easily obtained for its coincident characteristic dimension in two orthogonal directions. The performance characteristics achieved by the motor are: 1) a maximum linear speed of more than 60 mm/s; 2) a stroke of more than150 mm; 3) a driving force of more than 5.0 N; and 4) a response time of about 2 ms.

关键词： ultrasonic motor     quadrate plate     coincident frequency     alternant contact    

HTML PDF 收藏

Postprocessor development for ultrasonic cutting of honeycomb core curved surface with a straight blade

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0729-8

摘要： When ultrasonically cutting honeycomb core curved parts, the tool face of the straight blade must be along the curved surface’s tangent direction at all times to ensure high-quality machining of the curved surface. However, given that the straight blade is a nonstandard tool, the existing computer-aided manufacturing technology cannot directly realize the above action requirement. To solve this problem, this paper proposed an algorithm for extracting a straight blade real-time tool face vector from a 5-axis milling automatically programmed tool location file, which can realize the tool location point and tool axis vector conversion from the flat end mill to the straight blade. At the same time, for the multi-solution problem of the rotation axis, the dependent axis rotation minimization algorithm was introduced, and the spindle rotation algorithm was proposed for the tool edge orientation problem when the straight blade is used to machine the curved part. Finally, on the basis of the MATLAB platform, the dependent axis rotation minimization algorithm and spindle rotation algorithm were integrated and compiled, and the straight blade ultrasonic cutting honeycomb core postprocessor was then developed. The model of the machine tool and the definition of the straight blade were conducted in the VERICUT simulation software, and the simulation machining of the equivalent entity of the honeycomb core can then be realized. The correctness of the numerical control program generated by the postprocessor was verified by machining and accuracy testing of the two designed features. Observation and analysis of the simulation and experiment indicate that the tool pose is the same under each working condition, and the workpieces obtained by machining also meet the corresponding accuracy requirements. Therefore, the postprocessor developed in this paper can be well adapted to the honeycomb core ultrasonic cutting machine tool and realize high-quality and high-efficient machining of honeycomb core composites.

关键词： honeycomb core     straight blade     ultrasonic cutting     tool pose     postprocessor    

HTML PDF 收藏

Vibration characteristics and machining performance of a novel perforated ultrasonic vibration platform

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0730-2

摘要： Ultrasonic vibration-assisted grinding (UVAG) is an advanced hybrid process for the precision machining of difficult-to-cut materials. The resonator is a critical part of the UVAG system. Its performance considerably influences the vibration amplitude and resonant frequency. In this work, a novel perforated ultrasonic vibration platform resonator was developed for UVAG. The holes were evenly arranged at the top and side surfaces of the vibration platform to improve the vibration characteristics. A modified apparent elasticity method (AEM) was proposed to reveal the influence of holes on the vibration mode. The performance of the vibration platform was evaluated by the vibration tests and UVAG experiments of particulate-reinforced titanium matrix composites. Results indicate that the reasonable distribution of holes helps improve the resonant frequency and vibration mode. The modified AEM, the finite element method, and the vibration tests show a high degree of consistency for developing the perforated ultrasonic vibration platform with a maximum frequency error of 3%. The employment of ultrasonic vibration reduces the grinding force by 36% at most, thereby decreasing the machined surface defects, such as voids, cracks, and burnout.

关键词： ultrasonic vibration-assisted grinding     perforated ultrasonic vibration platform     vibration characteristics     apparent elasticity method     grinding force     surface integrity    

HTML PDF 收藏

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    

HTML PDF 收藏

声学综合无损检测技术

陈积懋

《中国工程科学》 2000年 第2卷 第4期   页码 64-69

摘要：

论述了检测复合材料和胶接结构不连续（缺陷）的新型多模综合无损检测技术。该技术以声与超声检测技术为基础，包含五种不同检测模式，用以检测复合材料与胶接结构的失粘、脱粘、分层、疏松、夹芯压皱及其他缺陷。它适用于复合材料与构件的制造、维修和使用现场。它的适用对象范围广泛，几乎覆盖了现有常用的复合材料和胶接结构。它的检测可靠性高，重复精度好。文章还讨论了组成多膜声学综合胶接检测仪的五种不同检测模式的原理，并从我们和国内外同行的大量实践经验出发，说明了综合无损检测技术的巨大发展前景。

关键词： 声学综合检测     综合无损检测     复合材料无损检测     机械阻抗分析     振动分析     共振检测    

HTML PDF 收藏

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    

HTML PDF 收藏

标题 作者 时间 类型 操作

Probabilistic analysis of secant piles with random geometric imperfections

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

硐室加深孔预裂爆破振动测试分析

申振宇,汪旭光,于亚伦,刘宏刚

期刊论文

A review of nondestructive examination technology for polyethylene pipe in nuclear power plant

Jinyang ZHENG, Yue ZHANG, Dongsheng HOU, Yinkang QIN, Weican GUO, Chuck ZHANG, Jianfeng SHI

期刊论文

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

期刊论文

Progress in terahertz nondestructive testing: A review

Shuncong ZHONG

期刊论文

Testing of tuberculosis infection among Chinese adolescents born after terminating the Bacillus Calmette--Guérin booster vaccination: subgroup analysis of a population-based cross-sectional study

null

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

density measurement for plastic injection molding via ultrasonic technology

期刊论文

Linear ultrasonic motor using quadrate plate transducer

Jiamei JIN, Chunsheng ZHAO

期刊论文

Postprocessor development for ultrasonic cutting of honeycomb core curved surface with a straight blade

期刊论文

Vibration characteristics and machining performance of a novel perforated ultrasonic vibration platform

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

声学综合无损检测技术

陈积懋

期刊论文

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

期刊论文