Search | Engineering

订阅投稿

首页工程期刊工程焦点工程成就工程前沿关于我们 English

资源类型

期刊论文 5

年份

2022 1

2021 1

2011 1

2010 1

2007 1

关键词

地质预报 1

岩石工程 1

支护技术 1

水电工程 1

爆破技术 1

锚固技术 1

展开︾

检索范围：

排序：展示方式：

Novel precision piezoelectric step rotary actuator

LIU Jianfang, YANG Zhigang, ZHAO Hongwei, CHENG Guangming

《机械工程前沿（英文）》 2007年第2卷第3期页码 356-360 doi: 10.1007/s11465-007-0062-2

摘要： A novel piezoelectric (PZT) precision step rotary actuator was developed on the basis of PZT technology. It adopts the principle of bionics and works with an inside anchoring/loosening of the stator and a distortion structure of the uniformly distributed thin flexible hinge to solve problems such as ineffective anchoring/loosening, low step rotary frequency, small travel, poor resolution, low speed and unsteady output. The developed actuator is characterized by high frequency (30 Hz), high speed (380 μrad/s), large travel (>270º), high resolution (1 μrad/step), and work stability. It greatly improves the ability to drive the existing PZT step rotary actuator. The new actuator can be applied in the field of micromanipulation and precision engineering, including precision driving and positioning and optics engineering.

关键词： developed stability ineffective anchoring/loosening technology piezoelectric

HTML PDF 收藏

Unravelling the bottleneck of phosphonic acid anchoring groups aiming toward enhancing the stability

《化学科学与工程前沿（英文）》 2022年第16卷第7期页码 1060-1078 doi: 10.1007/s11705-021-2117-z

摘要： Novel near-infrared sensitizers with different anchoring groups aiming toward improved stability and efficiency of dye-sensitized solar cells were synthesized. Adsorption of these dyes on the mesoporous TiO₂ surface revealed the dye adsorption rate of –CH=CH–COOH (SQ-139)>–CH=C(CN)COOH (SQ-140)>–PO₃H₂ (SQ-143)>–CH=C(CN)PO₃H₂ (SQ-148)>–CH=C(CN)PO₃H–C₂H₅ (SQ-157)>–PO₃H–C₂H₅ (SQ-151)>–CH=CH–COOH(–PO₃H₂) (SQ-162). The binding strength of these dyes on mesoporous TiO₂ as investigated by dye desorption studies follows SQ-162>SQ-143>SQ-148>SQ-139>SQ-157~SQ-151>SQ-140 order. The acrylic acid anchoring group was demonstrated to be an optimum functional group owing to its fast dye adsorption rate and better binding strength on TiO₂ along with good photoconversion efficiency. Results of dye binding on TiO₂ surface demonstrated that SQ-162 bearing double anchoring groups of phosphonic and acrylic acid exhibited>550 times stronger binding as compared to dye SQ-140 having cyanoacrylic acid anchoring group. SQ-140 exhibited the best photovoltaic performance with photon harvesting mainly in the far-red to near-infrared wavelength region having short circuit current density, open-circuit voltage and fill factor of 14.28 mA·cm^–2, 0.64 V and 0.65, respectively, giving the power conversion efficiency of 5.95%. Thus, dye SQ-162 not only solved the problem of very poor efficiency of dye bearing only phosphonic acid while maintaining the extremely high binding strength opening the path for the design and development of novel near-infrared dyes with improved efficiency and stability by further increasing the π-conjugation.

关键词： anchoring groups adsorption behaviour dye-binding strength squaraine dyes dye-sensitized solar cells

HTML PDF 收藏

Acupuncture is ineffective for chronic low back pain? A critical analysis and rethinking

Xuqiang Wei, Baoyan Liu

《医学前沿（英文）》 2021年第15卷第5期页码 767-775 doi: 10.1007/s11684-020-0785-6

摘要： Acupuncture is a promising treatment for relieving pain and improving lower back function in clinical practice. However, evidence from randomized clinical trials (RCTs) remains controversial. Most RCTs conclude that acupuncture procedures for chronic low back pain (CLBP) had no significant difference in efficacy and belonged to placebo. We carefully reviewed and analyzed the methodology and implementation of sham acupuncture in RCTs. Controversial evidence of acupuncture for CLBP is only a microcosm of the evaluation methodological limitation of acupuncture. Inappropriate selection of sham acupuncture controls, rigorous RCT research models, and incorrect interpretation of results may contribute to negative evidence. Evaluating and disregarding the holistic efficacy of acupuncture with an explanatory RCT model based on evaluation drugs may be unwise. Moreover, sham acupuncture is often proven to be non-inert, unreasonable, and with low fidelity. Pitfalls of the explanatory RCT model and sham acupuncture design should be avoided. Establishing a new evaluation system that is in line with the clinical characteristics of acupuncture and obtaining high-quality evidence are difficult but promising tasks.

关键词： chronic low back pain sham acupuncture acupuncture methodology therapeutic evaluation

HTML PDF 收藏

Experimental study on the progressive failure and its anchoring effect of weak-broken rock vertical slope

Hehua ZHU, Qianwei XU, Wenqi DING, Feng HUANG

《结构与土木工程前沿（英文）》 2011年第5卷第2期页码 208-224 doi: 10.1007/s11709-011-0111-0

摘要： To improve the understanding on the failure behavior and its anchoring effect of weak-broken rock slope, the rock of grade IV according to China is taken as reference prototype, and a series of model tests were carried out in laboratory. These tests can be divided into two categories, that is, with bolt reinforcement and without bolt reinforcement. In which, the stability of slope reinforced with different bolt diameter, different anchor length and different space are studied. The test results show that the collapse of slope is the combination of tension failure at the top and the compression-shearing failure at the bottom of the slope, and its failure process presents progressive characteristics. The contributions of bolt reinforcement are mainly reflected by the aspects of shear resistance, crack resistance and anti-extension. The reinforcement of blot not only can improve the vertical bearing capacity before failure, but also can reduce the vertical settlement and allow greater lateral rock wall deformation; what is more, the stress concentration degree in rock mass can be dispersed, which do help to improve the stability of slope rock mass.

关键词： progressive failure weak-broken rock slope model test bolt

HTML PDF 收藏

中国岩石工程技术的新进展

钱七虎

《中国工程科学》 2010年第12卷第8期页码 37-48

摘要：

在水电建设的岩石工程技术方面，介绍了三峡船闸高边坡稳定性及监控施工技术；深切河谷水电工程高边坡稳定性和支护技术；大跨度高边墙地下洞室群围岩稳定技术。在公路、铁路建设中的岩石工程技术方面，介绍了青藏铁路——穿越长年冻土层的施工技术；公路、铁路隧道中乌鞘岭隧道挤压大变形支护技术，高寒高海拔的风火山隧道、二郎山隧道施工技术；岩溶地区隧道超前地质预报技术。在矿业工程的岩石工程技术方面，介绍了煤矿巷道支护成套技术创新体系；低透气性煤层群无煤柱煤与瓦斯共采技术；深凹露天矿安全高效开采技术。另外，还介绍了岩石工程锚固新技术和精细爆破技术。

关键词：岩石工程水电工程支护技术地质预报锚固技术爆破技术