bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using the Breeder genetic algorithm to optimize a multiple regression analysis model used in prediction of the mesiodistal width of unerupted teeth
Authors: Stoica Florin , Boitor Cornel 
Published: September 2014

For the prediction of the unerupted canine and premolars mesiodistal size, have been proposed different variants of multiple linear regression equations (MLRE). These are based on the amount of the upper and lower permanent incisors with a tooth of the lateral support. Aim of present study was to develop a method for optimization of MLRE, using a genetic algorithm for determining a set of coefficients that minimizes the prediction error for the sum of permanent premolars and canines dimensions from a group of young people in an area Romania's central city represented by Sibiu. To test the proposed method, we used a multiple linear regression equation derived from the estimation method proposed by Mojers to which we adjusted regression coefficients using Breeder genetic algorithm proposed by Muhlenbein and Schlierkamp. A total of 92 children were selected with complete permanent teeth which had not clinically visible dental caries, proximal restorations or orthodontic treatment that requires the decrease of the mesiodistal size of teeth. For each of these models was made a hard dental stone which was then measured with a digital calliper, the instrument having an accuracy of 0.01 mm. To improve prediction equations, we divided data into training and validation sets. The Breeder algorithm, using the training set, will provide new values for regression coefficients and error term. The validation set was used to test the accuracy of the new proposed equations.
The Parallel One-way Hash Function Based on Chebyshev-Halley Methods with Variable Parameter
Authors: Nouri Mahdi , Safarinia Mahyar , Pourmahdi Payam , Garshasebi Mohammad Hossein 
Published: September 2014

In this paper a parallel Hash algorithm construction based on the Chebyshev Halley methods with variable parameters is proposed and analyzed. The two core characteristics of the recommended algorithm are parallel processing mode and chaotic behaviors. Moreover in this paper, an algorithm for one way hash function construction based on chaos theory is introduced. The proposed algorithm contains variable parameters dynamically obtained from the position index of the corresponding message blocks. Theoretical analysis and computer simulation indicate that the algorithm can assure all performance requirements of hash function in an efficient and flexible style and secure against birthday attacks or meet-in-the-middle attacks, which is good choice for data integrity or authentication.
Escherichia coli with virulence factors and multidrug resistance in the Plankenburg River
Authors: Lamprecht Corne , Romanis Marco , Huisamen Nicola , Carinus Anneri , Schoeman Nika , Sigge Gunnar O. , Britz Trevor J. 
Published: September 2014

Escherichia coli is a natural inhabitant of the gut and E. coli levels in water are considered internationally to be an indication of faecal contamination. Although not usually pathogenic, E. coli has been linked to numerous foodborne disease outbreaks, especially those associated with fresh produce. One of the most common ways through which E. coli can be transferred onto fresh produce is if contaminated water is used for irrigation. In this study, a total of 81 confirmed E. coli strains were isolated from the Plankenburg River as part of three separate studies over 3 years. During sampling, E. coli levels in the river were above the accepted levels set by the World Health Organization and the South African Department of Water Affairs and Forestry for safe irrigation of fresh produce, which indicates that transfer of E. coli during irrigation is highly probable. Multiplex polymerase chain reaction screening for pathogenic gene sequences revealed one enteroaggregative positive strain and four enteropathogenic positive strains. The four enteropathogenic strains were also found to be resistant to three or more critically and highly important antibiotics and were therefore classified as multidrug resistant strains. These results show that E. coli with enteropathogenic potential and multiple antimicrobial resistance properties has persisted over time in the Plankenburg River.
Structural Interactions with Fracture Treatments in the Horn River Basin of NE BC
Authors: Hards Eric , Marechal Francois , Welsh Jennifer , Verkhovtseva Natalia 
Published: September 2014

Abstract
This paper presents a case history describing the use of three-dimensional (3D) surface seismic and downhole microseismic data to understand and optimize a fracturing stimulation completion project performed in the Horn River basin (HRB) shale.
The behavior of the hydraulic fractures is interpreted from the data, and a geological theory is then used to further explain the observed data. The theory and observations are then used for completion and stimulation designs on the subsequent well pad.
The target intervals are in the HRB of northeastern British Columbia. They consist of Devonian age clastic sedimentary rocks of the Muskwa and Klua formation that overlie the carbonates of the Keg River formation. Fig. 1 illustrates the HRB geological schematic in the general area.
Rotary Steerable System With Optimized Functionally Integrated System-Specific Drill Bits Reduces Drilling Days and Extends Laterals in Northeastern US Horizontal Shale Plays
Authors: Hakam Carmel El , Davis Eric , Serdy Andrew , Spencer Reed 
Published: September 2014

Abstract
In the Marcellus and Utica shale plays in the northeastern United States, operators are continually seeking to optimize drilling performance and reduce overall drilling days of horizontal shale wells. This paper describes how several operators have maximized drilling performance and reduced drilling time per well by an average of two days in the Marcellus and Utica shales by adopting a new technology and employing drill bits that are specifically designed for the specific technology and application. The latest fleet of system-specific bit designs has enabled operators to repeatedly achieve more than 4,000 ft of footage drilled in a 24-hr period (well above the average footage per day achieved with conventional BHAs).
Most horizontal wells drilled in the Marcellus utilize conventional bent motor BHAs to drill the curve and lateral sections. However, the adoption of a new "pus-the-bit" rotary steerable system (RSS) by some operators has enabled them to reduce overall days per well and extend the length of the lateral sections. The unique aspect of the RSS is the customized complimentary fleet of drill bits designed in conjunction with the RSS, thereby, functionally integrating the bit into the tool. The new custom drill bits used with the RSS incorporate system-specific features to compliment the tool's drilling dynamics and optimize its drilling performance. Bit features such as cutter profile, gage cutter count configuration, polished cutters, cutter exposure and gage pad geometry were developed to improve build-up rates (BURs), rate of penetration (ROP), steerability and durability as well as to mitigate vibrations and any shale-balling tendencies specific to the RSS tool. Through successive bit design iterations, drilling performance with the RSS has steadily advanced with every horizontal job by reducing days spent drilling the curve and lateral sections.
This paper will present increased efficiency and monetary savings from the development of drill bits carried out in parallel with improving the RSS drilling system. The paper will show the improvements in comparison to offset wells and highlighting the money saved and reduced non-productive time (NPT).
Determining Interwell Connectivity and Reservoir Complexity through Frac Pressure Hits and Production Interference Analysis
Authors: Sardinha Christopher , Petr Christopher , Lehmann Jurgen , Pyecroft James 
Published: September 2014

Abstract
This paper presents a process for analyzing production interference and interwell hydraulic fracturing pressure hits for multi-well horizontal pads in unconventional reservoirs. Ten wells with varied spacing in separate formations are evaluated. The analysis determines the degree of connectivity between the wells to help assess the extent and complexity of the stimulated network. Many of these connections persist through flowback and early production. The results of the study impact decisions regarding well spacing, injection rate, perforation design and frac order.
A prescriptive completions program enabled observation of pressure interactions between wells during multi-stage hydraulic fracturing. Wellhead pressures are continuously recorded during all completions and flowback operations. The rate of pressure buildup plus the magnitude and frequency of the inter-well hits are studied. Pressure hits are then compared with production interactions between wells. Connections are mapped to form a comprehensive image of the fracture network.
In the pad studied, all wells had multiple hits with varying degrees of communication across the fracture network. Observations confirm that fractures had significant vertical and lateral growth establishing a highly complex network. Interference analysis indicates the connections between wells often diminish over time. As a final validation, the high degree of interaction and fracture overlap are shown to be consistent with high-resolution microseismic observations.
Establishing the extent of the effective fracture network is fundamental to deciding design variables. Multi-variable pad designs and production results can only be deciphered when viewed in conjunction with fracture interactions. The process discussed provides a simple way to observe and understand these interactions.
Does a Multi-Entry, Multi-Stage Fracturing Sleeve System Improve Production in Bakken Shale Wells Over Other Completion Methods?
Authors: Wellhoefer Ben , Eis Andy , Gullickson Geoffrey 
Published: September 2014

Abstract
Shale and unconventional reservoir wells require multiple completion options be available so that the best one can be selected to maximize the stimulation influence potential, enable efficient operations, and increase production potential. Shale and unconventional reservoir continuous resource wells are typically drilled horizontally with the completion system run in the lateral section of the wellbore. The completion design must enable the hydraulic fracturing of multiple discreet treatment zones in the target interval to help ensure economical production. Traditionally, unconventional reservoir wells have been completed using a plug and perforate methodology. This completion uses wireline intervention to set composite fracturing plugs for stage isolation and to perforate individual stages. Due to inefficiencies with this type of completion design, single entry fracturing sleeve systems (SE FSS) completions have gained acceptance. SE FSS offer a single entry point per stage and remove the need for wireline intervention thereby increasing completion efficiency. Recently, multi-entry fracturing sleeve systems (ME FSS) completions have been deployed in unconventional reservoir stimulation operations. ME FSS completions also do not require wireline intervention, and allow for multiple entry points per stage to be simultaneously stimulated. Even though it is optimal for unconventional reservoir development to have several completion alternatives, evaluation of the best method can be challenging.
This paper will evaluate the three dominant and currently applied completion methods by comparing wells in the Middle Bakken continuous resource play which have utilized all identified systems. The paper will discuss each of the three completion methods (Plug-and-Perforate, SE FSS, ME FSS), the completion design, and fracturing operations that are executed. The paper will then illustrate production results from using all three of the completion methods. This data will be drawn from similar well designs for comparison purposes.
Assessment of viability and production efficiency of ME FSS completions against other completion methods is the primary focus. Results will be presented based on production outputs obtained after a qualified 180 day period. Conclusions will also highlight the potential efficiency gains of a ME FSS completion versus traditional methods.
Effects of Pore Confinement on Rate-Transient Analysis of Shale Gas Reservoirs
Authors: Qanbari F. , Haghshenas B. , Clarkson C. R. 
Published: September 2014

Abstract
It is common practice to use PVT data measured in laboratories (i.e. bulk fluid properties) for reservoir modeling and production data analysis purposes. However, theoretical studies have shown that fluid properties (including critical properties, phase behavior, viscosity, density, etc.) change under nano-scale confinement in shale reservoirs due to the abundance of interactions between the fluid molecules and the pore walls (pore proximity effects). In addition to these effects, in nanopores, an adsorbed layer can form which could cause changes in the apparent permeability to the free gas phase. The purpose of this study therefore is to incorporate the effects of pore proximity and adsorbed layer thickness changes into rate-transient analysis. The transient linear flow period in particular is studied for this purpose as it is often the dominant flow period in shale gas wells.
An iterative integral method is used to solve the nonlinear partial differential equation (PDE) for fluid flow in the presence of pore proximity effects and changing adsorbed layer thickness. Fluid properties (i.e. viscosity and density) under confinement are simulated using critical property adjustments and conventional fluid property correlations. The simplified local density model is used to estimate the thickness of the adsorbed layer, and this is coupled with an apparent permeability equation, which accounts for diffusion and slippage phenomena, to quantify permeability alteration in the presence of an adsorbed layer. Stress-sensitivity of permeability is also accounted for.
The results of our analysis using simulated data show that neglecting proximity effects in linear flow analysis leads to overestimation of the linear flow parameter ( i.e. xfki) in nanoporous shale reservoirs. This in turn could cause errors in the derivation of fracture half-length, if permeability is known, or vice-versa.
The new modified analytical rate-transient analysis tools and procedures provided in this work will lead to improved linear flow analysis, should pore proximity and confinement effects be important. In general, this method can be used for inclusion of different pressure-dependent fluid and rock properties and processes in the analysis of shale gas reservoirs.
Entering a Liquid-Rich Shale Play Near the Top of the Learning Curve: Early Quantification and Application of Development Best Practices
Authors: Braun D. , Powell B. , Guo R. , Morad K. , Flint D. , Dixon R. K. 
Published: September 2014

Abstract
Exploitation of unconventional resources is evolving rapidly. Case in point: liquid-rich shale (LRS) plays, once impermeable source rock, are now a prime target for unconventional exploration and development, with economic plays, such as the Eagle Ford, proving the potential. However, given complex and expensive completion, drilling and production operations combined with relatively low production rates and commodity prices, slim economic margins will likely prevail for the foreseeable future. Hence, the difference between economic success and failure could be the pace at which an economically robust development plan can be conceived, tested and implemented.
With this in mind, entry into new plays must rapidly and intelligently build on all unconventional best practices to-date – of which there is no shortage. Unfortunately, most are presented as rules-of-thumb, intuitive-but-unquantifiable or come with a long caveat list. Thus, the authors of this paper chose to quantify the credible ranges of several selected best practices based on the belief that there are only a handful of key engineering and geological levers that have step-change influence on production and cost (as opposed to optimizations). We have built an unconventional development workflow that identifies them, quantifies them, risks them and constructs full field development scenarios, which are economically evaluated and ranked, using only initial exploration data. Thus, even early appraisal wells can be planned to mitigate development risks and ensure the highest value geological and engineering data is collected early and used to steer timely development decisions.
The workflow is not novel, but at its core it accepts the inherent uncertainty of unconventional reservoirs and seeks to test end-member cases to drive decision making. This workflow was applied by Shell while planning the development of the Duvernay LRS play in Canada and will be described in that context. It consists of: Identifying the key, play specific development leversGathering and analyzing analogue play data on these leversConstructing individual well production profiles and economicsBuilding field development "end game" scenariosEvaluating full development economics to understand total project value and robustness
Sequenced Fracture Treatment Diversion Enhances Horizontal Well Completions in the Eagle Ford Shale
Authors: Viswanathan Anup , Watkins Hunter , Reese Jennifer , Corman Andrew , Sinosic Brian 
Published: September 2014

Abstract
With the boom of the oil and gas activities in south Texas, our understanding of completions and completion optimization of multistage horizontal wells has been greatly enhanced. Various multiple-stage isolation techniques are currently being utilized. The success of any horizontal shale well depends on contacting maximum reservoir rock, causing operators to reduce interval length which, in turn, increases drilling and completions cost.
To enable extending the interval length and increasing effectively stimulated rock volume, a new sequenced fracturing technique was developed and successfully tested. The technique relies on a novel fracturing fluid diversion blend delivered downhole at high concentration levels, which are achieved by using degradable fibers to stabilize fluid fronts and prevent slug dispersion when displaced. Thus, only a minor amount of material is used, and the pill is seamlessly integrated into a fracturing design and execution to divert stimulation fluids to under-stimulated regions of the wellbore. The material degrades completely after the fracturing treatment has been completed, leaving no residual formation or fracture conductivity damage.
The technique was first applied on several wells without extending stage spacing. The consistent results and diversion performance led to introducing the technique to wells with increased stage spacing, with the objective of achieving higher productivity and higher operations efficiency.
The early diagnostic data from wells completed with this technology demonstrate that diversion was achieved and reservoir contact improved. On wells with restricted internal diameter and long stage spacing, this technique was the only viable option to complete a section of the wellbore. Surveillance measurements indicate that the fracture treatment covered the interval as planned.
Cost-effectiveness of membrane bioreactors treatment system for low-level phosphorus reduction from municipal wastewater
Authors: Young Thor , Smoot Sebastian , Peeters Jeff , Côté Pierre 
Published: September 2014

Phosphorus removal from municipal wastewater is primarily accomplished through a combination of biological uptake and chemical precipitation. This study examines the capital and operating costs of four strategies for phosphorus removal: conventional activated sludge (CAS), CAS followed by sand filtration, CAS followed by membrane filtration, and membrane bioreactors (MBR).
The cost-effectiveness of these four strategies to achieve three target levels of effluent total phosphorus is contrasted: 2.0, 0.3, and 0.1 mg/L. The impact of simultaneously achieving biological nitrogen removal in the system to achieve 10 mg/L total nitrogen is also considered. This study, which is balanced carefully to try to ensure a ‘level playing field’, reveals that MBR facilities are cost-competitive with CAS facilities when tertiary media filtration or tertiary membrane filtration is required for achieving moderate to high levels of phosphorus removal, particularly when simultaneous nitrogen removal is required.
Investor Heterogeneity, Auditor Choice, and Information Signaling
Authors: Wei Xu , Xiao Xiao , Zhou Yi 
Published: September 2014

SUMMARY
We develop a model of firms' auditor choices when presented with a heterogeneous group of investors. We show that firms' auditor choices in equilibrium depend on the composition of investors in the market. The signaling effect of choosing a high-quality auditor exists only when there is at least a certain proportion of sophisticated investors. If there is a sufficiently high proportion of sophisticated investors, then all firms will choose high-quality auditors. We also show that the overall audit quality in the market increases with an increasing proportion of sophisticated investors. When the audit market is differentiated and investors are heterogeneous, an increase in the penalty for firms that receive a qualified opinion will lead to a decrease in the overall audit quality in the market. Our conclusions remain valid even after taking audit fees, auditor quality change, and firm heterogeneity into consideration.
Use of contrast-enhanced ultrasonography to characterize adrenal gland tumors in dogs
Authors: Pey Pascaline , Rossi Federica , Vignoli Massimo , Duchateau Luc , Marescaux Laurent , Saunders Jimmy H. 
Published: September 2014

Abstract
Objective—To describe the contrast-enhanced ultrasonographic characteristics and vascular patterns of adrenal gland tumors in dogs and determine whether those features are indicative of malignancy or histologic type of tumor.
Animals—14 dogs with 16 adrenal gland lesions (10 carcinomas [8 dogs], 3 adenomas [3 dogs], and 3 pheochromocytomas [3 dogs]).
Procedures—Unsedated dogs with adrenal gland lesions underwent B-mode ultrasonography and contrast-enhanced ultrasonography ≤ 48 hours before adrenalectomy; contrast-enhanced ultrasonographic examinations were video-recorded. Macroscopic evaluation of the adrenal gland lesions and histologic examination of removed adrenal gland tissues were subsequently performed. Surgical and histopathologic findings and the ultrasonographic and contrast-enhanced ultrasonographic characteristics were recorded for the various tumor types. Time-intensity curves were generated from the contrast-enhanced ultrasonographic recordings and used to calculate regional blood volume (value proportional to area under the curve) and mean transit time (time the lesion began to enhance to the half-peak intensity).
Results—In adrenal gland carcinomas, tortuous feeding vessels were noticeable during the arterial and venous phases of contrast enhancement. Heterogeneity of contrast enhancement was evident only in malignant tumors. Compared with adenomas, adrenal gland carcinomas and pheochromocytomas had significantly less regional blood volume. Mean transit times were significantly shorter in adrenal gland carcinomas and pheochromocytomas than in adenomas.
Conclusions and Clinical Relevance—For dogs, evaluation of the vascular pattern and contrast-enhancement characteristics of adrenal gland tumors by means of contrast-enhanced ultrasonography may be useful in assessment of malignancy and tumor type.