Installation Techniques Research Articles

A Fractographic Investigation of a Failed Precombustion Chamber Nozzle from a Large Marine Diesel Engine

From 1998 until 2001 a series of engine failures occurred in a fleet of large marine diesel engines due to the failure of precombustion nozzles. The nozzles are screwed into the head of the engines and are held in place by a tightening torque and a high temperature ceramic adhesive. The preliminary findings of an engineering investigation after one such failure concluded that cracking occurred in the nozzle at the time of the installation, due to poor installation technique, and that this cracking resulted in the loss of tightening torque causing the nozzle to become loose. However, the investigation also recommended that fractography be undertaken to verify the cause of failure since this would influence the engineering solution. The current paper focuses on the fractography that was conducted on the failed nozzle to determine its mode of failure and provides a reminder of the importance of fractography in failure analysis.

The Construction Technique of Steel-Wood Composite Core Formwork in a Large Span Prestressed Hollow Box Guider

Based on the comparison of several types of core formwork for large span hollow box girder, their structural characters, and assemble and disassemble in application is analysed to find that steel-wood core formwork is a better choice. Then the installation technique of steel-wood core formwork is discussed, including assemble, disassemble and anti-floating counter measures. The practice in some large span prestressed hollow box girder construction prove that steel-wood core formwork is a simple but effective core formwork construction technique with technological economic advantages because of its low cost, high working efficiency and better accuracy..

Dynamic simulation on collision between ship and offshore wind turbine

By using ABAQUS/Explicit, the dynamic process of an offshore wind turbine(OWT) stricken by a ship of 5000DWT in the front direction is simulated. The OWT is located on a large-scale prestressing bucket foundation constructed by an integrated installation technique. According to the simulation results, under the ship collision, a certain range of plastic zone appears within a local area of arc transition structure of the bucket foundation, and the concrete plastic zone is seriously damaged. As the stress level of OWT tower is relatively low, the OWT tower is less affected. A great inertial force is generated at the top of the OWT tower as the mass of nacelle and blades is up to 400 t. The displacement of the tower is in the opposite direction of the ship collision at the end of 1 s under the action of inertial force. There is only a minor damage in the ship bow. Most of the kinetic energy is transformed into the plastic dissipation and absorbed by the arc transition structure of bucket foundation.

One-Year Prospective Study of 7-mm-Long Implants in the Mandible: Installation Technique and Crown/Implant Ratio of 1.5 or Less

This study prospectively evaluated the clinical prognoses of short implants (7-mm long) in the mandible. We investigated the clinical prognosis of short implants in 20 patients (46 implants) according to the installation technique (submerged or nonsubmerged), installation depth (5.5-mm depth, 7-mm depth), and crown/implant ratio. We investigated the marginal bone loss and peri-implant soft-tissue index 12 months after the final prosthetic delivery. Twelve months after prosthetic delivery, no statistically significant differences were observed in bone loss in relation to the type of installation technique, installation depth, or crown/implant ratio. The plaque index and pocket depth indexes were not influenced by the installation technique, installation depth, or crown/implant ratio. We observed marginal bone loss of 3.3 mm in 1 implant from the nonsubmerged group. The total 1-year success rate was 97.83%. Based on this 1-year success rate, short implants had a good clinical prognosis, regardless of the installation technique, installation depth, or crown/implant ratio.

Review: optical fiber sensors for civil engineering applications

Optical fiber sensor (OFS) technologies have developed rapidly over the last few decades, and various types of OFS have found practical applications in the field of civil engineering. In this paper, which is resulting from the work of the RILEM technical committee “Optical fiber sensors for civil engineering applications”, different kinds of sensing techniques, including change of light intensity, interferometry, fiber Bragg grating, adsorption measurement and distributed sensing, are briefly reviewed to introduce the basic sensing principles. Then, the applications of OFS in highway structures, building structures, geotechnical structures, pipelines as well as cables monitoring are described, with focus on sensor design, installation technique and sensor performance. It is believed that the State-of-the-Art review is helpful to engineers considering the use of OFS in their projects, and can facilitate the wider application of OFS technologies in construction industry.

Motion analysis on integrated transportation technique for offshore wind turbines

With the current state of offshore wind turbine construction technology, a major marine spread is necessary for the installation of the foundation, tower, and turbine. It is advantageous for offshore installation to be integrated into a single operation. The large-scale composite bucket foundation is the basis for a one-step integrated transportation and installation technique using a specialized transport vessel. The proposed transportation and installation technique will minimize the offshore operation and maximize the proportion of work carried out onshore with consequent benefits in terms of cost, quality, and safety. The self-floating composite bucket foundation is towed into the semicircle groove of the vessel and connected to the wire ropes of a stationary crane. Then the tower and turbine are attached to the foundation at the shore and the entire unit consisting of the foundation, tower, and turbine is loaded out from the quayside, transported to the site and set down on the seabed. During transport, half of the unit's weight is taken by the hoisting system of the vessel, and the remaining half of the weight is supported by air cushions inside the composite bucket foundation. A detailed model is studied to determine the motions of the vessel with two units to confirm the viability and feasibility of such a method of integrated transportation. The draft and air cushion are two effect parameters used to determine the dynamical characteristics of the transportation structure system. The results show that a smaller draft and a greater air cushion positively contribute to a safe transportation process. The viability and feasibility of this method of integrated transportation are confirmed by determining the motions of the various elements proposed by the detailed model.

Marginal Bone Preservation in Single‐Tooth Replacement: A 5‐Year Prospective Clinical Multicenter Study

Few long-term studies are available comparing immediate and conventional loading protocols of implant-supported single-tooth replacement. The aim of the present randomized controlled clinical trial was to evaluate prospectively the 5-year clinical and radiological outcome of immediate functional loading implants used in single-tooth replacement. One hundred fifty-one subjects, who required single-tooth rehabilitation in the area from position 15 to 25 and from 35 to 45, were enrolled in eight private clinics in Italy. A randomization protocol was applied to allocate the implants in three treatment groups: one control group and two test groups. In the control group, implant placement was performed according to a conventional drilling procedure, and the implants were submerged for 3 months before abutment connection and loading. Implants allocated in the test group 1 and 2 followed an immediate functional loading protocol. While in test group 1, implant placement was performed according to conventional drilling procedure, in test group 2, a modified implant installation procedure (osteotome technique) was applied. Clinical and radiographic examinations were performed during the 5-year follow-up, and technical and biological complications were registered. Although four implants (three in the test group 2 and one in the test group 1) were lost in the immediate functional loading groups in the first year of follow-up, no further implant loss occurred in any of the treatment groups in the following monitoring period up to 5 years. No significant differences on marginal bone level changes were observed between the treatment groups. About 52% of all implants showed bone gain in the period from 1-year to 5-year follow-up. The percentage of all implants that in the same interval of time showed bone loss was about 28%. Although few technical complications were recorded in the period of time up to 5 years, implants showing biological complication were 5.7%. It is suggested that implants installed with a conventional installation technique together with an immediate functional loading protocol may be considered as a valid treatment alternative in a long-term perspective when used in a single-tooth replacement in an esthetic area.

Development of the Damage Detection Method for CFRP Structures Using Distributed BOCDA Optical Fiber Sensor

The Brillouin optical correlation domain analysis (BOCDA) technology is one of the distributed optical sensing technologies utilizing the Brillouin scattering phenomena. The authors are developing, verifying and validating this technology. They are also developing the installation technique of optical fiber sensors, evaluating the durability of the BOCDA system and manufacturing the new device compatible to avionics bays for size. Furthermore, the authors are also improving the monitoring ability for composite damages. This paper reports the developmental status of the BOCDA monitoring ability for composite damages such as debonding at adhesive joints and micro-damages at bolted joints. First, debonding detection tests were conducted using carbon fiber reinforced plastics (CFRP) stiffened or repaired panels. In this test, test plates with a sheet stringer or a repair patch were applied tension load, and expanding of debonding areas was monitored by measuring strain distribution changes near these areas. Second, bearing damage detection tests were conducted using CFRP bolted joint specimens. In this test, multi-fastener single-lap CFRP specimens were applied tension load, and occurrences of micro-damages near bolt holes was detected. Micro-damages were detected by monitoring shapes changes of the Brillouin Gain Spectrum, which is one of the BOCDA measurement results.

Sensing System Provides Synchronized Acoustic Measurements

Young Technology Showcase Silixa’s iDAS (intelligent Distributed Acoustic Sensor) offers a solution for permanent and continuous downhole production monitoring and reservoir monitoring by overcoming the cost and technology challenges encountered with traditional point sensors. The iDAS enables wide-aperture acoustic array observation even in harsh environments, like high-pressure, high-temperature wells, and negates the need for irreversible pre-completion sensor placement. The iDAS measures the full acoustic field along the unmodified optical fiber up to tens of kilometres in length with a spatial resolution down to 1 m, capturing the full amplitude and phase of the incident wave on the sensing optical fiber up to frequencies >100 kHz with a wide dynamic range (>120 dB). The system enables high-quality synchronized coherent digital recording of acoustic waves with no crosstalk at every location along the fiber. These unique attributes make the iDAS technology particularly well-suited to the demanding applications encountered in oil and gas exploration and production. Principle of Measurement The iDAS functions by using a method based on optical time-domain reflectometry. When light is emitted into a fiber, the signal is reflected throughout the fiber length. These reflections are the result of a variety of mechanisms, including Rayleigh, Brillouin, and Raman scattering. By monitoring this scatter as a function of time following the emission of each sensing pulse, it is possible to build a map of the time variance of light-scattering properties throughout the fiber. This information can be analyzed to give a measure of the acoustic signal at each sensing zone along the fiber. Silixa’s iDAS uses a new digital optoelectronics architecture to rapidly and accurately measure this backscattered signal with a precision and speed that allows acoustic measurements from very low frequencies (<10 mHz) to high frequencies (>100 kHz). This sensing system can be retrofitted on existing standard optical-fiber cable installations, although superior performance can be achieved by using Silixa’s proprietary cables for logging operations and new permanent installations. Applications Silixa’s iDAS technology provides benefits through every stage of the life of a well. Since iDAS makes it possible to map acoustic propagation along the entire length of a borehole, the system creates the opportunity to perform real-time, continuous production and well-integrity monitoring. Further, distributed acoustics can facilitate seismic profiling in harsh, high-temperature downhole environments. Silixa has also developed a number of installation techniques for permanent as well as logging applications.

Field Measurement of P- and S-Wave Velocities for Wyoming Trona Deposit

A detailed field investigation of P- and S-wave velocities was carried out for the Wyoming trona deposit. The velocity measurement was performed at two field sites and included 11 transmission surveys. A total of 97 independent ray paths were generated from these surveys and utilized for the velocity calculation. The test sites consisted of two large pillars. The average travel distance of the signals utilized for the survey was 100 m. A high resolution data acquisition system was used with the sampling rate set at 50 kHz. The sensors were high sensitive accelerometers, with a flat response range of 50–5,000 Hz. These sensors were installed in the boreholes to avoid the attenuation problem caused by the fractured pillar surface. A special sensor installation technique was employed for reliable sensor installation in boreholes which could be oriented in any directions. The signals acquired from the transmission surveys were of very high quality. The frequencies of these signals were very high, ranged from 2,500 to 5,000 Hz, with 5,000 Hz being most typical. The P- and S-waves were well defined and separated. The timing error was estimated within 0.05 ms. The velocities calculated for all 97 survey lines were very consistent. The average P- and S-wave velocities were 5,108 and 2,640 m/s, respectively. The mean standard deviations were small, only 2.4 and 1.9 % for the P- and S-wave velocities. The 95 % two-sided confidence interval for the true P-wave velocity was 5,108 ± 24 m/s and for the S-wave velocity was 2,640 ± 10 m/s. With the consideration of the test conditions associated with this investigation, including multiple test sites, large pillars, excellent signal quality, a very large database, and extremely consistent results, we believe that the P- and S-wave velocities determined from this investigation are accurate, reliable and representative for the Wyoming trona deposit.

Mitigation Of Scattering Polarization In F.O. Regarding The Method Of Installation

Today there are value added services such as ADSL, or the use of technologies such as GSM, which cause the transfer of large volumes of information on their transport networks. In turn, these networks are formed by optical fiber links, which are limited by several factors such as PMD. This phenomenon of light reduces the efficiency of transmission systems and the bandwidth. It has been found that the PMD can be seriously affected during transport and installation. This paper to compare the different installation techniques based on the value of PMD associated with the use of them. The results show that the use of an appropriate method of installation as the installation of fiber optic in tritubo by blow, would mitigate the PMD value associated with the link respect other installation methods, and demonstrate the importance of reducing efforts lateral traction and torsion of the installation process in the optical fiber during installation.

Land-Art, Ecologie, Politică şi Societate

Abstract The Land-Art was integrated to Postmodernism by the most art historians, having as arguments the important affinities presented by the two artistic phenomena, both at the expressing modalities level but, especially, at the level of principles and, of the ideological sphere. The Postmodernism intended, as it is well-known, to parody or to interpret, in a proper way, a cultural tradition whose authority had become disturbing the Land-Art also started an innovating programme in the 60s -70s of the 20th century, through which the millenary art of the landscape was questionable, trying this way, a new and radical art-like approach of nature. The Art-Land was given various other names, syntagms which points out the work modalities or the materials used in the creation art: “Sociological Art”, “Earth Art”, “Works Art”, “Environmental Art”, “Earthworks”, “The Art of Landscape”, “The Sculpture of Landscape”, “The Walking Art”. The Land Art borrowed, in a great measure, the own means of expression of other tendencies which were performing on the artistic stage in the same time, such as the technique of installation, some of the principles experienced by Process-Art, by the Environmental Art or by Happening. The most representative land artists knew to integrate all the borrowings to a new vision, an original one, which, for the first time, was turning the nature into the support of the artistic creation. Apart from the point of view through which the Land Art is understood as an integral part of Postmodernism, there are also opinions, supported by well-known specialists, through which the Modernism of the 60s from the past century is seen as a possible origin of the Land-Art, especially if we have in mind the works of some great modern artists, such as Henry Moore, Robert Morris, Anthony Caro, Yves Klein and Tony Smith. Land Art presents two different ways of demonstration, hostile from the point of view of attitude towards nature and public: on the one hand some of the land artists look for the privacy of the act of artistic creation in the natural environment (one example this way is Richard Long), others, on the contrary, are guided by an art with clear social implications (e.g. the typical case of Christo). The ecological position of the tendency is underlined by the artists ' spokesman, Robert Smithson, who thinks that it should be adopted a committed, fighting attitude, pragmatically sheltered itself towards future.

Comparison of rapid load pile testing of driven and CFA piles installed in high OCR clay

The current analysis of rapid load tests (RLT) such as Statnamic is normally based upon empirical correlations with static pile tests in similar soils. In certain soil types, such as clays, the number of case studies used to develop analysis and allow selection of appropriate rate effect correction are limited. Due to these limitations, no distinction is made in the selection of correction factors between pile type and pile installation techniques. In clay soils it is well known that driven piles may have a significantly enhanced capacity over cast in situ piles of similar cross-section. To test the effect of pile installation techniques on RLT analysis, RLT testing and static testing were undertaken on precast driven concrete piles and cast in situ CFA piles installed in high plasticity London Clay. The results show that the installation technique does not appear to affect the magnitude of the rate effects, provided modifications are made to the analysis to account for the previously reported differences in static capacity between different installation techniques. Based upon the findings, it is suggested that a distinction should be made in RLT analysis between pile type and installation techniques, and for existing analysis techniques, further case studies based on rate correction parameters are required, especially in clay soils.

Measured and Predicted Response of a New Jetted and Grouted Precast Pile with Membranes in Cohesionless Soils

AbstractWith increased urbanization, deep foundation (bridges, signage, walls, etc.) selection is moving toward the minimization of disturbance and installation time, as well as addressing quality control and assurance issues. Unfortunately, many types of deep foundations involve noise and vibration during installation (e.g., driven piles) or integrity and reduced resistance issues (e.g., drilled shafts, both conventional and post grouted tip, continuous flight auger piles). This paper presents a new foundation type, a jetted and grouted precast pile, which uses the advantages of several proven deep foundation installation techniques. The installation of the new pile is comprised of three distinct phases: (1) pressurized water-jetting of a precast pile into the ground; (2) side grouting of the pile; and (3) tip grouting. The pile has two separate side grouting zones, each with its own grout delivery system. Each grout zone is covered with a semirigid membrane, which results in radial expansion of the soil...

Applicability Analysis and Installation Techniques of Driver Feedback Sign on Freeway in China

The Driver Feedback Sign (DFS) has been widely used abroad to reduce the vehicle speed to improve traffic safety level, but it only be used on a few of freeways and urban expressways in China, and there have no research on its application effect. In order to popularization and application the DFS in China, the paper analyzed the DFS application situation at home and broad by document retrieval, comparatively analyzed implement effect before and after installing DFS on Badaling freeway by vehicle speed survey and questionnaires survey. At last, the paper comprehensively analyzed the applicability of DFS on freeway in China and proposed the installing requirement and technical requirement.

Offshore wind—an overview

In this article, the state of the art technology developments and challenges that need to be overcome as the emerging offshore wind industry matures over the coming decade to become a significant source of electricity generation are discussed. A brief summary of the history and drivers of the offshore wind industry is provided followed by more detailed analysis of the current market, focusing on the major developments in Northwest Europe. The offshore wind industry is in the process of shifting from shallow water, near shore projects, to deeper water projects, much farther from shore. This has necessitated the development of larger turbines, a range of substructures, and more advanced installation techniques. The primary components constituting an offshore windfarm—turbines, foundations, substructures, electrical and transmission infrastructure, installation, and operations and maintenance—are analyzed and the opportunities for improvements in both technology and productivity within each component are presented. Technical advances in turbines, substructures, vessels, and the electrical infrastructure will allow larger turbines to be constructed and deployed. These, combined with productivity improvements gained through serial production in manufacturing and construction, represent the most significant ways in which the industry will advance in the future.This article is categorized under: Wind Power > Systems and Infrastructure

Validating and Improving Models for Vibratory Installation of Steel Sheet Piles with Field Observations

Vibratory driving is the most common installation technique for steel sheet pile walls. In practice, the assessment of the feasibility of this installation process is mainly based on rules of thumb, on numerical and empirical models or on experts opinions. In order to improve these prediction methods and formulas, 252 observations from the Dutch engineering practice have been compared with six different types of models. This comparison has been carried out applying the receiver operating characteristic (ROC) curve technique, which is new in geotechnical engineering. This paper introduces the ROC-curve technique to estimate mainly the quality of a model and to be able to optimize parameters and variables in the model. 252 field observations were used to re-examine prediction methods for the minimum required vibration force and to prove the ROC method works. The paper shows this technique is suitable for three purposes: (1) determining the quality of a model, (2) objectively comparing several models to each other, given certain assumptions and (3) for optimizing thresholds within a model. The model with added professionals’ experience proves to perform equally well as the numerical model Hypervib-I.

A retrievable sensor installation technique for acquiring high frequency signals

The use of in-seam waves for void detection in mines requires the capability of capturing high frequency signals over large distances. For instance, the Airy phase of Love waves which are used for void detection in coal mines ranges from several hundred to over one thousand Hertz and the expected travel distance of these signals is at least 90m (equivalent to a detection distance of 45m) for the technique to be considered practical. In order to obtain high quality and broadband signals, sensors are conventionally grouted at the bottom of boreholes so that the attenuation due to the fractured surface is minimized and the coupling effect is improved. However, to be economically feasible, the expensive and high sensitive sensors must be retrievable so that they can be used repeatedly at the same or other locations. Because of these concerns, a retrievable sensor installation technique was developed. This paper provides a detailed review of the technique as well as a brief discussion of its applications. The technique is simple and reliable for both installation and retrieval operations and can be used for boreholes oriented in any directions. The technique has been demonstrated in over 200 sensor installation/retrieval operations under various borehole conditions, including bituminous coal, anthracite coal, shale, sandstone and trona. With this technique, we were able to detect the high frequency signals required for our projects. For instance, the signals used at a trona mine for void detection have a typical frequency of 5kHz with the travel distance of 150–200m. The results of these operations have shown that sensors installed in the prescribed manner exhibit predictable, consistent, and repeatable performance. The technique also provides an economical and reliable means for many other field seismic monitoring applications where high quality and broadband signals are essential, such as microseismic monitoring and geotomography studies.

Study on Installation Technique for Steel Structure Dome

The large-scale steel dome construction method is studied in the paper. Combined with Shandong province museum of steel construction dome, the piecewise processing methods are determined. According to the type of weight component chose lifting equipment types and model, aiming at the actual situation of construction formulated the steel structure installation overall process, the stress of the bed-jig to install a performance is calculated, and the steel frame column installation method is studied. The engineering experience and research content in the paper can provide a reference for the similar engineering.

Offshore wind in China

China has made slower progress than planned in the installation of offshore wind capacity since the commissioning of its first turbine in 2007. The majority of projects reside within the nearshore intertidal zone and little experience outside this zone has been gained. The rate of progress is now increasing and the Government has specified that new projects should be further offshore in deeper waters. Much of the East coast of China has good to excellent wind energy resource and shallow waters extend for tens of kilometres from the shore. Soft ground conditions and the occurrence of typhoons complicate the otherwise favourable conditions for offshore wind development. To overcome these local challenges, Chinese developers have tested a range of different foundation types including unique approaches such as high-rise pile cap foundations. Installation techniques, vessels, and wind turbines have been developed to suit the local conditions and these have been supplemented by methodologies and equipment from the European offshore wind industry.