Design of Close-Fit Liners for the Rehabilitation of Gravity Pipes

2021 ◽  
Author(s):  
Keyword(s):  
Close Fit

Mapping Complex Injectite Bodies With Multiwell Electromagnetic 3D Inversion Data

2021 ◽  
Vol 62 (1) ◽  
pp. 109-121
Author(s):  
Nigel Clegg ◽  
◽  
Endre Eriksen ◽  
Kevin Best ◽  
Ingeborg Tøllefsen ◽  
...  
Keyword(s):  
Three Dimensional ◽  
3D Inversion ◽  
Independent Verification ◽  
Major Increase ◽  
Multiple Frequencies ◽  
Geological Complexity ◽  
Azimuthal Resistivity ◽  
Subsurface Resistivity ◽  
The Vertical Distribution ◽  
Close Fit

Electromagnetic (EM) inversion processing of ultradeep resistivity data has advanced from one dimensional (1D) to three dimensional (3D). These advances have helped improve the geological complexity that can be imaged and provide additional reservoir information. The large depth of investigation (DOI) of ultradeep LWD EM tools means that distant boundaries might not be detected by any other sensor in the tool string, making it difficult to verify the results. As inversion results represent a model of the subsurface resistivity distribution and not a direct measurement, it is important to have high confidence in the results. Directly comparing the component data measured by the tool to the modeled component data from the inversion across multiple frequencies provides confidence in the resultant model where the data have a close fit. However, as measurement sensitivities decrease with distance, there is potential for non-uniqueness, generating a model that is geologically unrealistic. Increased confidence can be achieved with independent verification of the model. This paper details results from a trilateral well in an injectite reservoir wherein the sand distribution was expected to be complex. The 1D inversions showed the vertical distribution of the sand, but the results were sometimes distorted by lateral resistivity variations. The 3D inversion of the data allowed the lateral resistivity variations to be resolved. These results can be corroborated by direct comparison with azimuthal resistivity images. Additionally, the laterals all diverged from the same main bore and remained close together initially in an area containing major sand injectites. The 3D inversions from two of the wells overlap and define similarly shaped structures, providing confidence in the 3D inversion model. In complex geobodies, such as the injectites described, significant lateral variation in the reservoir distribution is expected, which is not captured by 1D inversion. Understanding the shape of these structures and their potential connectivity using 3D inversion provides a major increase in reservoir understanding that is critical to completion design.

Bubble dynamics and oxygen transfer in a hypolimnetic aerator

1998 ◽  
Vol 37 (2) ◽  
pp. 293-300 ◽  
Author(s):  
Vickie L. Burris ◽  
John C. Little
Keyword(s):  
Gas Phase ◽  
Bubble Size ◽  
Oxygen Transfer ◽  
Bubble Dynamics ◽  
Water Flow Rate ◽  
Flow Rates ◽  
Wide Range ◽  
The City ◽  
Close Fit ◽  
Water Supply Reservoirs

A hypolimnetic aerator operating in one of the City of Norfolk's water supply reservoirs was tested. Dissolved oxygen (DO) profiles, water flow rate, and gas-phase holdup were measured over a wide range of applied air flow rates. A model that was developed to predict oxygen transfer in a Speece Cone was modified to conform to the conditions of the hypolimnetic aerator. By varying a single parameter (the initial bubble size) the model was found to provide a close fit to the experimental DO profiles as well as the observed gas-phase holdup. The model was used to show that a doubling in oxygen transfer may be achieved if initial bubble size is reduced from 5 mm to 2.5 mm. Knowing the initial bubble size, it should be possible to predict water velocity by incorporating the effect of momentum. Further work is now underway to test this approach and to examine the possibility of extending this generalized model to cover the range of hypolimnetic aeration and oxygenation devices.

scholarly journals A comparative study of trenchless technologies versus traditional open trenching for the replacement of ageing potable water pipelines

2014 ◽  
Author(s):  
◽  
Shanley Hay
Keyword(s):  
South Africa ◽  
Potable Water ◽  
Survey Questionnaire ◽  
Support Tool ◽  
Total Cost ◽  
The Public ◽  
Pipe Bursting ◽  
Water Pipelines ◽  
Pipeline Networks ◽  
Close Fit

The urgent need to rehabilitate or replace ageing deteriorated buried potable water pipeline networks is one of the many critical service utility provision challenges faced within the municipalities in South Africa. The majority of these unreliable deteriorated pipeline networks consist of un-dipped (not coated with bitumen) AC piping which have long passed their planned economic and technical lifespan. Traditionally, the open trenching method has been utilised for the replacement of aged and deteriorated piping. However, this traditional open trenching method has shown to be expensive and difficult to implement, particularly in congested high traffic use urban areas. The need to rehabilitate or replace the ageing deteriorated buried potable water pipelines in South Africa, taking into account the above mentioned expensive factors has a solution. This solution is termed ‘trenchless technology’ and sometimes also termed ‘no dig’. Recent advancements in trenchless technologies now include innovative methods such as pipe bursting, close-fit lining and sliplining. Close-fit compact pipe manufactured by Wavin Overseas B.V. was newly introduced in South Africa in 2010 for the rehabilitation of deteriorated pipelines. These trenchless methods require further research into their technical application merits, drawbacks and costs in relation to the traditional open trenching method in order to determine which method is more expensive and also least suitable. Traditionally, the ‘total cost’ associated with pipe rehabilitation or replacement projects consisted only of the direct costs. The indirect and socio-economic inconvenience costs were often ignored and resulted in costly expenses to the municipalities. However, this research will show that these indirect and socio-economic inconvenience costs must form part of the total cost of a project as it assists with the successful completion of the project without expensive unforeseen costs to the municipalities. In addition, this research will provide insight as to which indirect and socio-economic inconveniences are dominantly experienced by the public. To achieve this, a quantitative socio-economic survey questionnaire was developed. This questionnaire was aimed at residents and business owners who were affected during a project of this nature. This research study will serve as a support tool to municipalities of South Africa when selecting a pipe rehabilitation or replacement method. This support tool will provide key technical merits and drawbacks of the traditional open trenching method, pipe bursting method, close-fit compact pipe method and sliplining method. In addition, this research study will compare the ‘total cost’ of the traditional open trenching method against the trenchless pipe bursting method. The decision making process lies in the hands of the municipal technical managers. Therefore, their knowledge and experience of up to date information on trenchless methods (as well as the traditional open trenching method) is vitally important. This research provides insight as to the knowledge and experience of technical municipal staff on trenchless methods, its application and use in South Africa. A quantitative survey questionnaire was developed by the researcher. This questionnaire was aimed at technical staff in the water departments of district and local municipalities of South Africa. The results of the above questionnaire surveys formed part of the eThekwini Water and Sanitation (EWS) Feasibility study funded by the Dutch Government. When comparing the costs of the trenchless pipe bursting method against the traditional open trenching method, the results revealed that trenchless methods are undoubtedly cheaper and far less disruptive to the public. The results of the socio-economic survey revealed that trenchless methods were preferred by the public since it was less disturbing and the hindrances experienced were also far less than the traditional open trenching method. The results of the technical municipal survey questionnaire revealed that at least 50% of municipal technical staff of South Africa are not adequately informed about trenchless methods, its application and technical merits and drawbacks respectively. This survey questionnaire revealed that South Africa may be advancing over the years on the use of trenchless methods, however, more educating in the form of training, seminars and other methods of marketing must be undertaken starting at a municipal level.

scholarly journals A model-based method for detecting persistent cultural change using panel data

2020 ◽  
Author(s):  
Stephen Vaisey ◽  
Kevin Kiley
Keyword(s):  
Panel Data ◽  
Cultural Change ◽  
Structural Equation ◽  
Cultural Beliefs ◽  
Local Environment ◽  
Theoretical Models ◽  
The Other ◽  
Equation Modeling ◽  
Survey Responses ◽  
Close Fit

Kiley and Vaisey (2020) recently published a method for assessing whether survey respondents appear to be changing their beliefs between waves or whether they instead appear to be repeating fixed responses with temporary local influences. This question is important because these processes reflect very different theoretical models of the evolution of “personal culture.” That is, if cultural beliefs are primarily public and responsive to external discourse, we should observe more updating as people respond to changes in their local environment. On the other hand, if cultural beliefs are primarily something learned early, then “settled dispositions” should be relatively resilient to change. In this paper, we build on Kiley and Vaisey (2020) and introduce an alternative method for distinguishing between cases where respondents appear be actively updating their responses and situations where respondents’ responses appear to be settled. This method, based on structural equation modeling, provides a close fit to the theoretical models outlined in Kiley and Vaisey (2020) and provides even stronger support for their claim that most survey responses reflect settled dispositions developed prior to adulthood.

A 3D Complexity-Adaptive Approach to Exploit Sparsity in Elastic Wave Propagation

Geophysics ◽  
2021 ◽  
pp. 1-64
Author(s):  
Claudia Haindl ◽  
Kuangdai Leng ◽  
Tarje Nissen-Meyer
Keyword(s):  
Degrees Of Freedom ◽  
Computational Cost ◽  
Parameter Tuning ◽  
Performance Limits ◽  
Absorbing Boundary ◽  
Adaptive Approach ◽  
Order Of Magnitude ◽  
Speed Up ◽  
Complex Settings ◽  
Close Fit

We present an adaptive approach to seismic modeling by which the computational cost of a 3D simulation can be reduced while retaining resolution and accuracy. This Azimuthal Complexity Adaptation (ACA) approach relies upon the inherent smoothness of wavefields around the azimuth of a source-centered cylindrical coordinate system. Azimuthal oversampling is thereby detected and eliminated. The ACA method has recently been introduced as part of AxiSEM3D, an open-source solver for global seismology. We employ a generalization of this solver which can handle local-scale Cartesian models, and which features a combination of an absorbing boundary condition and a sponge boundary with automated parameter tuning. The ACA method is benchmarked against an established 3D method using a model featuring bathymetry and a salt body. We obtain a close fit where the models are implemented equally in both solvers and an expectedly poor fit otherwise, with the ACA method running an order of magnitude faster than the classic 3D method. Further, we present maps of maximum azimuthal wavenumbers that are created to facilitate azimuthal complexity adaptation. We show how these maps can be interpreted in terms of the 3D complexity of the wavefield and in terms of seismic resolution. The expected performance limits of the ACA method for complex 3D structures are tested on the SEG/EAGE salt model. In this case, ACA still reduces the overall degrees of freedom by 92% compared to a complexity-blind AxiSEM3D simulation. In comparison with the reference 3D method, we again find a close fit and a speed-up of a factor 7. We explore how the performance of ACA is affected by model smoothness by subjecting the SEG/EAGE salt model to Gaussian smoothing. This results in a doubling of the speed-up. ACA thus represents a convergent, versatile and efficient method for a variety of complex settings and scales.

scholarly journals Dwarf Galaxies and the Black–Hole Scaling Relations

2020 ◽  
Author(s):  
Andrew King ◽  
Rebecca Nealon
Keyword(s):  
Black Hole ◽  
Dwarf Galaxies ◽  
Initial Distribution ◽  
Scaling Relations ◽  
Massive Galaxies ◽  
Stellar Feedback ◽  
Stellar Masses ◽  
Black Hole Masses ◽  
Close Fit ◽  
Fundamental Physical

Abstract The sample of dwarf galaxies with measured central black hole masses M and velocity dispersions σ has recently doubled, and gives a close fit to the extrapolation of the M∝σ relation for more massive galaxies. We argue that this is difficult to reconcile with suggestions that the scaling relations between galaxies and their central black holes are simply a statistical consequence of assembly through repeated mergers. This predicts black hole masses significantly larger than those observed in dwarf galaxies unless the initial distribution of uncorrelated seed black hole and stellar masses is confined to much smaller masses than earlier assumed. It also predicts a noticeable flattening of the M∝σ relation for dwarfs, to M∝σ2 compared with the observed M∝σ4. In contrast black hole feedback predicts that black hole masses tend towards a universal M∝σ4 relation in all galaxies, and correctly gives the properties of powerful outflows recently observed in dwarf galaxies. These considerations emphasize once again that the fundamental physical black-hole — galaxy scaling relation is between M and σ. The relation of M to the bulge mass Mb is acausal, and depends on the quite independent connection between Mb and σ set by stellar feedback.

Accessory Gear Box Architecture Evaluation Tool

2014 ◽  
Author(s):  
Pankaj Sharma ◽  
Thomas Moniz ◽  
Vinod Chaudhari
Keyword(s):  
Design Space ◽  
Gear Train ◽  
Minimum Size ◽  
High Fidelity ◽  
Preliminary Design ◽  
Evaluation Tool ◽  
Architecture Evaluation ◽  
Short Time ◽  
Structured Approach ◽  
Close Fit

An architectural modeling tool has been developed to support Accessory Gearbox (AGB) design. This is a structured approach which allows the Preliminary Design team to design an AGB with high fidelity in a short time and earlier in the design process. The program can accommodate a large variety of accessories with different attributes to generate a gearbox of minimum size. The final gearbox shape includes curvature which enables a close fit to the engine carcass. By setting the size, shape and location of the gearbox and accessories earlier, the designer can begin the process of locating external configurations around the gearbox more efficiently. The tool systematically explores the design space to optimize geometry based on multiple design criteria. It successfully constructs the intermediate gear train needed within the gearbox. It provides graphical output to the user with primitive models of the gears, accessories and housing. Once located in engine coordinates, these primitives provide the reference for the next level for detailed design.

The Rationale for CAD-CAM Uncemented Custom Hips: An Interim Assessment

1995 ◽  
Vol 5 (2) ◽  
pp. 52-62 ◽  
Author(s):  
J. Hua ◽  
P.S. Walker ◽  
W. Muirhead-Allwood ◽  
G. Bentley ◽  
C.J. McCullough
Keyword(s):  
Stem Length ◽  
Long Term Results ◽  
Ha Coating ◽  
Standard Design ◽  
Cad Cam ◽  
Early Primary ◽  
Torsional Stability ◽  
Lateral Flare ◽  
Close Fit

The purpose of this paper is to examine whether the rationale for CAD-CAM Custom Hips is realised in clinical practice. Previous studies demonstrated that custom uncemented stems, with a close fit proximally and a sliding fit distally, produced stresses closer to normal than for other stem types, which should result in the preservation of proximal bone. Custom stems showed less micromotion, especially in torsional loading, and hence should demonstrate interface osseointegration. The hips are designed and manufactured using specially written software. The standard design includes proximal macro-grooves with HA coating, an anterior flare, a lateral flare, a collar, and a smooth distal stem for a sliding fit. Elective features are added such as proximal stem twist and neck retroversion in CDH, increased stem length to bypass defects, curvatures in AP and ML views, and distal cutting flutes when extra torsional stability is required. From 1989 to 1994, 411 cases were carried out, approximately one-third in each of the categories of OA, JCA/CDH, and revision. Studies were made of the available radiographs at yearly intervals, while DEXA scans were taken of the RNOHT patients pre-operatively, at 6 months and then yearly. There were four failures requiring revision, three of the early primary design without HA coating, and one a revision design. The radiographs in primary hips showed complete proximal bone-implant apposition in 81% of all cases. The DEXA scans showed that the mean bone mass after two years for all seven Gruen zones was greater than 90%. It was concluded that the CAD-CAM HA-coated Custom Hips showed bone and interface stability up to this time. The hip has played a useful role in providing the ideal stem for each particular case, which may result in an improvement of long-term results, compared with the use of off-the-shelf implants.

scholarly journals Model Error in Covariance Structure Models

Methodology ◽  
2008 ◽  
Vol 4 (4) ◽  
pp. 159-167 ◽  
Author(s):  
Donna L. Coffman
Keyword(s):  
Error Rate ◽  
Null Hypothesis ◽  
Type I Error ◽  
Sampling Error ◽  
Model Error ◽  
Type I ◽  
Empirical Power ◽  
Parameter Drift ◽  
Type I Error Rate ◽  
Close Fit

This study investigated the degree to which violation of the parameter drift assumption affects the Type I error rate for the test of close fit and the power analysis procedures proposed by MacCallum et al. (1996) for both the test of close fit and the test of exact fit. The parameter drift assumption states that as sample size increases both sampling error and model error (i.e., the degree to which the model is an approximation in the population) decrease. Model error was introduced using a procedure proposed by Cudeck and Browne (1992). The empirical power for both the test of close fit, in which the null hypothesis specifies that the root mean square error of approximation (RMSEA) ≤ 0.05, and the test of exact fit, in which the null hypothesis specifies that RMSEA = 0, is compared with the theoretical power computed using the MacCallum et al. (1996) procedure. The empirical power and the theoretical power for both the test of close fit and the test of exact fit are nearly identical under violations of the assumption. The results also indicated that the test of close fit maintains the nominal Type I error rate under violations of the assumption.

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