浅析水利工程中水闸加固施工技术

高压喷射灌浆技术在地下和基础工程防渗加固工程中的应用十分广泛。由于高压喷射灌浆施工技术的优越性,在实际水利工程施工中常采用此技术进行防渗漏处理,文章对高压喷射灌浆施工技术的特点、流程及施工工艺要求进行了探讨。     

水利工程基础灌浆施工技术研究

在水利工程中,灌浆技术是进行地基处理中比较常用以及十分重要的工程措施,广泛地应用于大坝坝体的加固处理与防渗工程中。水利工程的特殊要求使得它们的地基必须经过严格处理,才能达到水利工程必须有的防渗与稳定的各项性能要求,本文在此对基础灌浆施工技术做了详细的研究。     

工民建防渗堵漏中化学灌浆法的应用措施

化学灌浆法是修补和补强混凝土结构缺陷或裂缝的常用方法之一，它是通过专用设备，向裂缝中注入高分子化浆利料。经聚合、交联等化学反应生成高聚物，在处理过的部位胶结、增强与加固并形成整体，达到防渗、堵漏和加固的目的。近几年，化学灌浆法已广泛应用于大坝坝基基础加固和防渗、混凝土缺陷修复等诸多工程领域。     

浅谈帷幕灌浆

帷幕灌浆是处理地基与防渗的一种重要技术,现已被广泛采用。本文以梁家坪水库除险加固工程为背景,详细地介绍了帷幕灌浆技术的特点及施工过程,对充分发挥帷幕灌浆在水库除险加固工程中的应用有积极意义。     

中小型水库除险加固中灌浆技术的施工应用分析

灌浆技术在水库除险加固工程中应用较多,通过灌浆技术,可以消除坝体、坝基渗流隐患,提高防渗能力和稳定性。本文通过重庆市下涧口水库土坝除险加固工程,为防止土坝渗透变形失稳,对坝体采用了劈裂灌浆,坝体基岩与左坝肩山体岩层采用帷幕灌浆处理,论述了二种灌浆方法采用的施工工艺各有特点,效果显著,都达到了预期目的。     

水利工程基础施工灌浆技术分析

灌浆技术是水利工程建筑物建设过程中一项基础施工技术。施工灌浆技术被广泛的运用到大坝坝基防渗和加固处理中,是提高大坝稳固性与安全性的重要技术措施。大坝与水库的地基是否稳固直接关系到水利工程的整体质量,一般情况下,需要进行进一步的处理后才能达到稳定与防渗的要求。在施工过程中多采用基础施工灌浆技术对大坝和水库进行加固防渗处理,所以本文选取基础施工灌浆技术加以介绍。     

论水库除险加固工程中的充填灌浆技术

本文阐述了某水库除险加固工程中对输水洞顶、库区左岸台地充填灌浆处理技术要点,并对整个过程进行了控制、观测、记录。     

闹德海水库帷幕灌浆施工与质量控制

水工建筑物尤其是坝基工程,其渗漏和基础的完整性是影响工程运行和安全的重要因素。在水利工程中,灌浆是解决水文地质问题和确保基础完整的关键技术措施之一。本文介绍了闹德海水库除险加固帷幕灌浆的施工与质量控制。     

水利工程高压喷射灌浆技术探讨

高压灌浆技术作为水工建筑物地基处理中常用和重要的工程措施，在大坝坝基防渗和加固处理中得到广泛的应用。文章针对水利工程高压喷射灌浆技术进行了分析与探讨。     

水利工程中灌浆施工技术探讨

在水利水电工程中,灌浆技术是处理地基时常见的施工措施,也是大坝坝基进行防渗与加固施工处理中的常用措施。现主要针对在水利水电工程中,灌浆施工的控制措施进行分析,旨在与同行交流,从而确保水利水电工程的质量。     

Improvement of magnetic induction-wire sawing process using a magnetic system

Magnetic induction-free abrasive wire sawing is a hybrid process that applies a homogeneous magnetic field to transport more abrasives into the sawing channel. This causes the performance of wire sawing significantly improved. Magnetic field strength is a key factor in determining the magnetic force acting on the magnetic abrasives, then affecting the quantity of abrasives adsorbed on the saw wire surface. However, the background magnetic induction strength produced by two permanent magnets is limited in this process. To further investigate the influence of magnetic field strength on the wire sawing performance, a magnetic system, which is based on the magnetic circuit design principle and the structure of single-wire sawing machine, is designed and fabricated. The magnetic field characteristics of the designed magnetic system are investigated both by numerical simulations and experiments. An experimental setup that installs the fabricated magnetic system on the single-wire sawing machine is built to conduct the magnetic induction-wire sawing experiments. The results show that the optimal magnetic induction strength is about B₀?=?135?mT. In this case, the kerf loss is decreased by 10% compared to the free abrasive wire sawing technology without a magnetic field.     

大型冷锯机锯切噪声特性

采用非稳态噪声测试和时频细化分析方法进行大型冷锯锯切过程噪声特性研究。对锯切过程不同时段噪声进行测试及对噪声信号剔除背景声后做时频细化分析。分析得出：锯切噪声声压级高、辐射频率时变性强、声能量聚焦于锯切横向且高频突出。该研究结果对复杂机械（风机、压缩机等）运动状态下噪声场的测试、声场特性分析及其噪声治理具有重要理论指导和技术支撑。     

多层工业厂房的振动测试及裂缝病害分析

针对多层织造厂房的振动及裂缝病害问题,采用有限元建模分析结构的振动特性,并进行了现场振动测试和裂缝病害调查。根据实测数据的时域和频域分析结果,研究了厂房及机器的振动频率和能量分布特点;结合振动幅值的对比分析,探究厂房结构裂缝病害的原因,提出了改进措施,为厂房的减振设计和裂缝预防提供建议。     

Targeting the stem cell niche with regenerative biomaterials

Regenerative medicine aims to restore form and function to aged, injured, and diseased tissues. One strategy that is gaining traction is in vivo regenerative medicine. Many adult tissues possess stem and progenitor cells that are enlisted to repair minor tissue damage after insult. However, in the setting of disease, aging, or criticalsized injuries, the microenvironment may lack structural elements, physical, and/or chemical cues required to drive repair to completion. Natural and synthetic materials offer an opportunity to facilitate the repair process by restoring the natural reparative capacity of adult tissues. Using design criteria selected based upon an understanding of the inductive niche cues that naturally instruct stem and progenitor cell behavior and fate, it is possible to elicit tissue repair by implementing a cell-free approach. This review highlights recent studies that assess biomaterials for in vivo regenerative medicine applications and demonstrate a capacity for controlling stem and progenitor cell behavior to restore tissue form and function.     

火力发电厂锅炉受热面管泄漏原因分析

一直以来,高温过热器爆管事故都是影响电厂安全运行的主要因素之一,且造成的损失最大。该文结合现场工作的实际对某电厂1号锅炉末级过热器泄漏原因进行了讨论。通过宏观检验、化学成分分析、力学性能试验及显微组织观察等多种试验手段,对该受热面管进行了较为全面的分析,以期对改善锅炉受热面管失效提供帮助。分析得出该末级过热器的泄漏为长时过热所致,泄漏处的显微组织为铁素体加碳化物,珠光体球化达5级,并存在大量蠕变裂纹。     

Cracks,microcracks and fracture in polymer structures: Formation,detection, autonomic repair

Polymers and polymer composites are susceptible to premature failure due to the formation of cracks and microcracks during their service time. Evolution of cracks and microcracks could induce catastrophic material failure. Therefore, the detection/diagnostics and effective repair of cracks and microcracks are vital for ensuring the performance reliability, cost effectiveness and safety for polymer structures. Cracks and microcracks, however, are difficult to detect and often repair processes are complex. Biologically inspired self-healing polymer systems with inherent ability to repair damage have the potential to autonomically repair cracks and microcracks. This article is a review on the latest developments on the topics of cracks and microcracks initiation and propagation in polymer structures and it discusses the current techniques for detection and observation. Furthermore, cracks and microcrack repair through bio-mimetic self-healing techniques is discussed along with surface active protection. A separate section is dedicated to fracture analysis and discusses in details fracture mechanics and formation.     

Fracture Strength of Photovoltaic Silicon Wafers Evaluated Using a Controlled Flaw Method

Propagation of pre‐existing micro cracks and their associated residual contact stresses, generated from the wafer sawing process, is the leading cause for photovoltaic (PV) silicon wafer/cell breakage during handling and processing. In the current work, the impact of a single micro crack on the fracture strength of PV silicon wafer is investigated based on a controlled flaw method. Radial/median cracks with controllable scales are introduced through microindentation at the center of a PV silicon sample to simulate micro cracks resulting from wafer sawing, handling, or thermal processing. Results indicate that the fracture strength of PV silicon wafer decreases linearly with the increasing of the microindentation load (radial crack scale). In addition, it is found that the impurity carbon plays an important role in the contact cracking‐fracture process. The fracture strength increased ≈21% when the substitutional carbon concentration is increased from 1.2 × 10¹⁸ to 6.4 × 10¹⁸ cm^?3.     

Comparison of the effectiveness of boron/epoxy and graphite/epoxy patches for repaired cracks emanating from a semicircular notch edge

The adhesively bonded composite patch repair technique has been used to restore or extend the service life of the cracked aluminium structural components because of its efficiency. In this study, the finite element method is used to analyse the performance of the different bonded composite patches at a semicircular lateral notch and the repair of cracks emanating from this kind of notch. The knowledge of the stress distribution in the neighbourhood of the cracks is important for the analysis of their repair according to the geometry of the patch. The effects of the mechanical and geometrical properties on the variation of the stress intensity factor in the crack tip were highlighted. The effects of the adhesive properties and of the patch size on the stress intensity factor variation at the crack tip in mode I were also highlighted. The comparison between the double and single patch repairs is also given in this study. The results obtained show that the stress intensity factor of the crack tip repaired by two composite patches, is reduced to a half compared to the one that is repaired only by one patch. The orientation of fibres possessing a higher rigidity perpendicularly to the crack propagation considerably influences the reduction of the stress intensity factor. The adhesive properties must be optimised in order to increase the performance of the patch repair or the reinforcement.     

Cracking analysis of bolster cover plate in C70 freight wagons

After two year service, cracks are frequently found at the under surface of the bolster cover plate which seriously affect the reliability of the freight wagon. The stress state of bolster cover plate should be analyzed on the basis of preliminary analysis, residual stress test, static stress test and dynamic stress test. The scope of this paper is to study the causes and characteristics of the cracks, which performed by fracture mechanics analysis and FEM analysis as well as stress tests. The research results have then been used for predicting the crack initiation life and propagation life.     

Investigate the causes of cracks in welded 310 stainless steel used in the Flare tip

The present study examines the causes of the cracks in welded 310 stainless steel that has been used in the Flare tip. According to the tests, including metallographic examination, macroscopic hardness test and scanning electron microscopic analysis, the reasons for the nucleation and growth of the cracks in the weld zone have been discussed. The results show that, because of the service temperature of Flare tip between 500 and 900 °C, and hydrocarbon gases such as methane, ethane, sour gas and carbon dioxide that are the combustion products, the component surface has been oxidized and carburized. Thus, the surface carburized oxide layer and also the subsurface damage can be fertile field for the nucleation of cracks. Likewise, the presence of sigma phases, austenite dendrites and interdendritic delta ferrite can cause a drop in toughness in the weld zone and provide fields for the crack growth in the weld zone.