bluuebunny/crossref_metadata_2025 huggingface dataset:
Model-Based Control in Managed Pressure Drilling
Authors: Stakvik Jon Åge , Berg Christian , Kaasa Glenn-Ole , Graham Robert , Torrealba Antonio
Published: March 2017

Increased use of Managed Pressure Drilling (MPD) has enabled a significant improvement in drilling operations through the ability to accurately control pressure within a narrow window and by actively managing the annular pressure profile. However, the technology has not yet reached its full potential; well control events involving a gas influx causes two-phase flow in the well and can lead to severe deterioration of pressure control performance. In this study, a robust model-based MPD control system is presented and results from drilling a well in the Umm al-Quwain region in the UAE demonstrate invaluable benefits for both normal operations and during well control events.

Due to its transient nature, drilling has always been a complicated operation and requires highly skilled personnel to achieve the desired pressure control accuracy. The introduction of automated MPD systems tries to implement more robust and safer control over well control operations that were previously manual tasks, however, this is still a challenge since wellbore conditions are constantly changing. This has prompted the need for proactive and model-based control techniques that act in advance to optimize the performance based on measurements and knowledge of the system. The development of this state-of-the-art MPD control system involved detailed validation in a high-fidelity simulator and thorough tests of robustness and performance in a full-scale flow loop with continuous gas injection capabilities, with focus on two-phase flow and gas influx handling.

Results from field operations show that the model-based MPD control system maintains robust performance during planned operations such as connections and drilling ahead. Based on pump flow measurements surface back-pressure or bottom hole pressure are maintained constant during fast pump ramp-down and ramp-up without the use of a back-pressure pump. Usually, MPD control systems require strict procedures on pump ramp speed to maintain constant pressure during transient operation. In this paper, the model-based control system implemented is shown to handle irregular pump flow changes and still maintain constant surface back-pressure or bottom hole pressure. In particular, a simulated pump emergency shutdown is shown where the pumps are stopped in less than 20 seconds. The MPD control system still managed to maintain constant bottom hole pressure by closing the chokes in a controlled manner.

In summary, this paper presents a field implementation of a fully model-based MPD control system that demonstrates its ability to compensate for irregular pump flow changes. Throughout these irregular pump flow changes, the control system maintains constant bottom hole pressure or surface back-pressure. Furthermore, the system demonstrates the ability to maintain the desired pressure control precision in all normal operations and during all unplanned events experienced during the operation.
Improved Through-Christmas-Tree P&A Plug Placement with New Innovative Cementing Methodology
Authors: Olsen M. , Sætre T. , Hanssen R. , Waagen M. , Sirevaag B. , Lindanger C. , Gustafsson J. R.
Published: March 2017

When the production of a platform well is no longer profitable, two options are available—either perform permanent plug and abandonment (P&A) or reuse the slot by plugging the original well and sidetracking. P&A requires setting barrier elements in the wellbore to prevent hydrocarbon migration between potential flow zones and to the surface. In most cases, it is financially beneficial to perform as much of this work as possible during an intervention phase before rig operations begin, thus saving rig operating expenses.

Most conventional barriers are balanced cement plugs, and setting a cement plug requires a drilling rig to handle the workstring through which the cement is placed, crew, and associated equipment [e.g., blowout preventer (BOP)]. However, the rig time spent performing P&A could be used more productively, such as drilling and completing new wellbores. An operating and a service company developed a method for setting the primary P&A cement plug toward the reservoir without a drilling rig. The cement is set through the Christmas tree using a specialized wireline-set packer as a base and wiper plugs installed on a specialized spool piece to isolate the cement and indicate completion of the job. This paper explains the method and equipment and presents three case studies from the Norwegian sector of the North Sea.
CFD Modelling of Observed Cuttings Transport in Oil-Based and Water-Based Drilling Fluids
Authors: Sayindla Sneha , Lund Bjørnar , Ytrehus Jan David , Saasen Arild
Published: March 2017

Cuttings transport has been a topic of research for many years. It has been observed that drilling fluids with similar properties according to the API standard can have significantly different behaviour with respect to the efficiency of cuttings transport. Oil based drilling fluids have been considered to be superior to water based drilling fluids when it comes to the hole cleaning, even if the fluid properties are equal as measured in accordance with API specifications. Despite this well-known fact, very limited studies are available in the literature to address this issue. Experimental studies with various oil-based drilling fluids and water-based drilling fluids were conducted in a 10m long flow loop under identical and controlled conditions. Further to understand the physics behind the observed differences in the cuttings transport efficiency, we have developed an Eulerian-Eulerian multiphase computational fluid dynamics (CFD) model using commercial software ANSYS FLUENT. Experimental values from the flow loop experiments are compared with the CFD model results. CFD model helps to fill the gap in the results, which could not be obtained using experiments. The experimental results confirm that the annular frictional pressure loss in a fully eccentric annulus are significantly lesser than the values predicted by using models available in the literature for concentric annulus. CFD model includes realistic conditions like eccentric annulus and flow velocities. CFD model is used to conduct simulations for a wide range of parameters and the obtained results will be used to develop improved correlations for the prediction of cuttings transport.
Improving the Structural Integrity and Sealability of Float Valves With Optimized Float Bore Design
Authors: Holcomb Spenser R. , Gokhale Samit , Lee Kang
Published: March 2017

In many instances subs and stabilizers are bored to be used with a float valve in a box connection facing up-hole rather than down-hole. Sometimes the requirements for float bore depth, which are derived for a "box-down" float bore, are not sufficient to ensure the proper sealing of the float valve within the float bore in this "box-up" configuration. Additionally, regardless of float bore orientation, there is a chance that the float bore depth requirement can be long enough that the float bore runs into the pin connection of the sub on which it is machined. This can result in high stress in the float bore which could lead to fatigue cracks and a reduced load capacity of the tool due to a decrease in cross sectional area.

This paper details the design methodology used to ensure the proper sealing of float valves used in box-up float bores. Finite element analysis (FEA) was conducted to determine the distance from the back of the float bore to the shoulder of the pin connection necessary to substantially reduce the stress experienced as a result of connection make-up forces.

The new design methodology ensures proper sealability of float valves and structural integrity of the tool. New requirements based on this methodology have been implemented by various manufacturers and vendors with successful results.

A case study is provided which describes how a gap in current industry accepted inspection practices led to a sub with a float bore that was machined long enough to reach the shoulder of the pin connection to be overlooked. This led to the failure of the sub downhole. The paper provides a reasoned approach to new criteria needed for float bore design and makes the case for the standardization of float valves.
Development of New Pitting Acceptance Criteria Using Axi-Assymetric Thread Models to Improve Service Life and Reduce Repair Costs of Rotary Shouldered Connections
Authors: Gokhale Samit , Oak Sushil , Lee Kang
Published: March 2017

Rotary Shouldered Connections (RSCs) are subjected to harsh downhole environments and aggressive fluids that can cause pitting damage. Pitting, especially in the thread roots, increases the likelihood of fatigue crack initiation and propagation. Currently, no industry standard provides quantitative analysis of the effects of pitting on the fatigue life of RSCs. This often leads to deployment of a conservative acceptance criterion of disallowing pitting in any thread roots; resulting in frequent repair and recuts of RSCs, and at times reducing the service life of the components.

This paper details the analysis performed and methods adopted to assess the effects of pitting on fatigue life of RSCs. Six API connections commonly used on small, medium, and large size drill pipe and bottom hole assembly (BHA) components were modeled. Finite Element Analysis (FEA) was used to examine stresses in different thread roots of these connections. Connections with and without stress relief features were analyzed. A methodology was developed to integrate the effects of stress concentration caused by a pit into the stresses obtained from FEA analysis.

It was found that the stresses in many thread roots, even with a pit, were lower than the stresses in the last engaged threads. This result was used to establish new pitting acceptance criteria allowing pitting in some thread roots as long as the stresses were lower than the maximum stress found in the last engaged threads.

This study provides a scientific approach towards assessment of pitting damage. The study shows that a significant number of threads could be allowed to have pitting without compromising the overall fatigue life. Based on these results, universal inspection criteria were developed covering all API connections to provide well-defined, consistent and user-friendly method of inspection. These new acceptance criteria will reduce the cost of frequent machining, repair and replacement of components.
A New Analytical Model for Jarring Analysis
Authors: Zhang Yuan , Samuel Robello
Published: March 2017

Extensive jar models currently exist. When a hammer hits an anvil in a jar, a strong stress wave is generated in the drillstring. Such jar models have significant limitations because most do not account for the stress wave in the lower collar. However, when the hammer hits the anvil, both the upper and the lower collars deform to resist impact from the hit. Thus, there are two stress waves generated in both the upper and lower collars at the same time. The stress wave in the lower collar is the key reason for such impact force at the stuck point.

This paper discusses a new analytical model for jarring analysis based on two directional propaganda stress wave theories. It assumes that the energy from the hammer divides into two parts; one part travels upward to ground and the other moves downward to the stuck point. An equation is proposed to calculate the maximum impact force that can be determined, despite whether the jar can move the stuck pipe. New equations are proposed to calculate the jarring period and impact force. This can help achieve the most effective jar placement in horizontal wells.

Additionally, this paper reveals that increasing the energy ratio in lower collar can enhance jarring effectiveness significantly. The stress in the lower collar can be enhanced by increasing its section area. Impact force at the stuck point differs from the impact force at the anvil. A stronger stress wave in the lower collar generates a larger stuck force at the stuck point.
A Simple Method for Identifying Fracture Initiation Pressure
Authors: Naidu R. N. , Rylance M.
Published: March 2017

A reliable interpretation of Fracture Initiation Pressure (FIP) provides key information for both efficient well planning and construction. With the trend towards drilling ever deeper offshore wells, depleted zones and more complex well paths, the available mud weight window continues to tighten, so an improved knowledge of the FIP becomes essential in enabling robust designs and risk reduction strategies that together promote safe and efficient operations.

A number of methods are currently used across the Industry to estimate FIP values for drilling and completion applications. These methods involve the direct interpretation of data from injection tests, such as Diagnostic Fracture Injection Tests (DFIT), Formation Pressure Integrity Tests (FPIT) or even Wireline Formation Tests (WFT). In this paper, the authors propose and present a simplistic yet effective approach to derive values for the FIP from such typical pumping test data. The method is based on long established principles linking the pressure, volume and in-situ rock properties of the system being tested.

This paper provides a number of examples to demonstrate the application and validity of the approach, including the consideration of scaled laboratory block tests, through to actual field data. The relationship between FIP, FBP and closure pressure is presented and discussed for all of these cases. The method is based on early-time wellbore stiffness considerations and as such complements and augments the more conventional fracture closure analysis approach from decline data. Using this technique, additional valuable information may be extracted even from only partially completed tests, where formation breakdown analysis by conventional means may either be impossible to perform or at best is somewhat inconclusive.

In summary, while there are many and varied techniques that have been widely developed in support of obtaining FIP, the quality, the repeatability and assurance of these approaches is often incomplete and can sometimes be misleading. The simplistic methodology that is outlined and presented here provides a complementary approach, with the potential to offer a more consistent estimation of this key pressure control parameter. The method also provides the possibility of identifying the FIP in those situations where the currently available data (quantity and/or quality) would suggest that conventional methods might well fail to deliver an unbiased interpretation.
Gas Influx into Drilling Fluids During Flow Check Operations as Affected by Gas Absorption Characteristics of the Drilling Fluid
Authors: Linga Harald , Bjørkevoll Knut Steinar , Skogestad Jan Ole , Saasen Arild
Published: March 2017

The paper addresses the gas loading characteristics of the drilling fluid and its influence of the gas influx rate during the flow check operation. In particular, the resulting fluid expansion in the wellbore annulus and the capability to detect gas kick at HPHT process conditions will be discussed for selected drilling fluids.

For the evaluation of the applicability of flow check operations for the detection of gas influx, the time response to the drilling fluid expansion during natural gas influx is addressed in terms of drilling fluid gas loading properties, influx severity and influx area.

The physical gas loading rate of natural gas into the drilling fluid is described as a first order kinetic mass transfer process including the gas loading capability for the multicomponent system of drilling fluid and natural gas, in addition to the gas influx characteristics at the wellbore–formation boundary.

When operating the fluid system of natural gas–drilling fluid in the liquid phase region, a continuous gas influx will at some point give more distinct expansion of the fluid mixture in the wellbore. This occurs for the maximum gas loading of the drilling fluid. Such distinct change in sensitivity in the volume expansion response is not encountered when operating the system of drilling fluid–natural gas in dense phase. For selected cases relevant for HPHT drilling, the volume expansion response during flow check operation is compared for drilling fluid with gas loading characteristics either representing single liquid phase or dense phase gas loading. With the methodology described it is readily shown that the interpretation and design of the flow check operation should be carefully selected when approaching dense phase conditions or if the gas loading capability of the drilling fluid is considerable. This is particularly important for oil-based drilling fluids featuring high gas loading capability.
Maximizing Tubular Capacity and Well Integrity Under Near-Yield Loading
Authors: Nowinka J. , Meijer G. , Miller S.
Published: March 2017

Achieving well integrity demands knowing how much loading your tubulars can withstand, but what happens when near-yield loading causes unexpected deformations that are not predicted by code design and conventional elastic design theory? It begs the question, are harsh operating conditions and narrowing design safety margins increasing the potential for well failures? Alternatively, can tubulars be safely pushed even harder without compromising well integrity?

This paper raises industry awareness, demonstrates material test results, and proposes steps to account for possible near-yield load effects so that well designs can fully use the available tubular material capacity and be cost effective without compromising the long-term integrity of the well. Examples of near-yield load scenarios leading to substantial plastic deformation observed in laboratory testing are presented, and ways to determine when those effects need to be considered in elastic design methods are proposed.

The paper illustrates the effects of near-yield loading on tubular deformations using results of mechanical testing on a P110 material sample under cyclic uniaxial and multiaxial load. Uniaxial load cycles with stress amplitude below the rated yield strength showed substantial growth of plastic strain in only a few cycles. Combined-load tests on small-scale tubular P110 specimens loaded with axial force and internal pressure cycles also demonstrated pronounced near-yield load effects.

We discuss the significance of material behaviors that trigger plasticity at stresses below the measured yield strength and contribute to severity of near-yield load effects; such as changes in the stress-strain response due to elevated temperature exposure, directional dependence of material properties, and cyclic softening. We draw conclusions on how tubular material properties and operational loading extremes need to be assessed and balanced to maintain structural integrity of wells in anticipated operational scenarios.

To maximize capacity of completion tubulars, the complexity of near-yield load effects needs to be characterized with technically rigorous yet practical means. This paper points to relatively simple material tests for determining the propensity for near-yield loading effects of common OCTG materials, and suggests initial considerations for incorporating near-yield load considerations in tubular design.
Improving Casing Integrity by Induction Brazing of Casing Connections
Authors: Ernens D. , Hariharan H. , van Haaften W M. , Pasaribu H. R. , Jabs M. , McKim R.
Published: March 2017

Brazing technology allows metallurgical joining of dissimilar materials using a filler material. In this paper brazing technology applied to casing connections is presented. The initial application was triggered by challenges with mechanical and pressure integrity after expansion of casing connections. Creating a strong bond between the pin and the box could resolve this. Brazing was selected because of the combination of ductility and high bond strength and the relatively fast process to create the bond. The brazing process or temperature-torque-time process (TTT) is performed using regular casing connections, a filler material deposited by flame spray and a flux. Two processes were developed, one for expandable (VM50) grade material and one for quenched and tempered grade material. For this a rig ready (CLASS 1 DIV 1) prototype brazing system was developed consisting of an induction coil as the heat source, an environmental chamber to shield the hot work, and a modified power tong to provide torque. The results of a series of brazing trials on 8-5/8″ and 9-5/8″ casing connections are presented. The brazed connections were subsequently capped end pressure tested, expanded (when applicable) and load cycled. It is concluded that both processes produced leak tight casing connectors before and after expansion (when applicable) as shown by full scale tests
New Optical Sensor System for Improved Fluid Identification and Fluid Typing During LWD Sampling Operations
Authors: Cartellieri Ansgar , Kischkat Tobias , Sroka Stefan , Meister Matthias
Published: March 2017

In recent years different new services for formation sampling while drilling operations were introduced. The provided and implemented technology is primarily focused on the delivery of representative single-phase fluid samples. The formation sampling while drilling tools are equipped with various unique fluid identification sensors. These sensor modules deliver multiple physical properties and are commonly used for clean-up monitoring. Due to the extended downhole time during long drilling runs and the tough drilling condition ruggedized sensor elements have to be implemented. In addition, the same challenges regarding pressure, temperature and size as with wireline tools have to be considered.

The described logging-while-drilling (LWD) fluid analysis and sampling service is now extended by delivering optical absorbance spectroscopy and fluorescence measurements under in-situ conditions. This sensor system is added to the already existing sensor elements like pressure and temperature as well as measurement cells for density, viscosity, sound speed and optical refractive index. In addition, the lately introduced compressibility value derived from the electro-mechanical pump offers a bulk measurement, where localized sensors observe scattered data. As while drilling applications are often limited by the reduced bandwidth between the downhole tool and the surface acquisition system readings from the new optical sensor modules will be added to the fluid-typing algorithm, previously based on density, compressibility, refractive index and sound speed measurements, for improved predictions during sampling operations.

This technology should expand the application of fluid analysis in the downhole environment, gaining a deeper understanding of the reservoir fluid as well as improving the reservoir characterization and classification. With the new optical sensor system which provides distinct wavelength measurements in the visible, near infrared as well as ultraviolet range, a more detailed analytics of the formation fluid is possible. It will enhance the differentiation between water based mud, formation water and injection water as well as oil based mud and oil. It improves contamination monitoring and delivers a more detailed chemical composition while sampling. This new sensors will increase the success of fluid analysis only jobs.

Field examples will demonstrate the new sensor capabilities and will evaluate the data accuracy. The data interpretation allows for a broad comparison between different environments and the according sensor behavior. The review includes results from different reservoirs in various regions around the world.
An Industry-First 7-5/8 in. Drill Pipe Like Tubular Facilitates Deep Offshore Completions and Interventions by Saving Time and Reducing Cost.
Authors: Corbin Kevin , Begnaud Taylor , Elliott Greg , Sanclemente Leianne , Babineaux Joshua , Brock Jim , Plessis Guillaume , Muradov Andrei
Published: March 2017

Tubulars with gas-tight, rotary-shouldered connections are used as the conduit between the surface vessel (rig) and subsea wellheads in deepwater operations. Requiring no specialized tools and using standard rig equipment, they provide a fast, safe, and cost effective way to run completion landing strings and intervention pipe. Tubulars for these operations must provide a large internal drift diameter to allow for clearance of the wellhead crown plug and installation of completion components. These strings have been limited to 6-5/8 in. pipe allowing for a maximum drift diameter of 5-1/2 in., which is insufficient to run and retrieve the wellhead crown plugs of many large ID subsea trees. Trees with larger crown plugs require operators to use casing tubulars increasing deployment time, requiring casing running crews, incurring higher repair costs and time, thereby increasing overall costs.

A completion landing string (CLS) was developed using a 7-5/8 in. pipe and a built-for-purpose, large drift, gas-tight, pressure-rated, rotary-shouldered connection (7-5/8 CLS). This new connection technology optimized the outside diameter and make-up torque to be compatible with the iron roughnecks and pipe handling equipment of the current Gulf of Mexico rigs.

Product development and performance validation is detailed with a special emphasis on the enabling connection technology. The paper expands on manufacturing challenges and design choices made to assure ease of rig operations, including modifications to slips and elevators. Finite element analysis (FEA) and physical testing to validate performance are described. Steps taken before the initial deployment to assure compatibility with the rig equipment are explained. Finally, the paper will show data from the offshore field trials and initial deployments. Lessons learned are shared.

This industry-first, purpose–built, gas-tight completion and intervention tubular provides 6-1/8 in. internal drift diameter and can be safely deployed using conventional pipe make-up and handling equipment reducing overall cost.
Well Collision Avoidance Management and Principles
Authors: Sawaryn S. J.
Published: March 2017

The well collision avoidance management and principles presented in this paper are a culmination of the work and consensus of industry experts from both operators and service companies in the SPE Wellbore Positioning Technical Section (WPTS). This is not a new subject, but current guidance is disparate, company specific and occasionally contradictory. As a result, the guidance can be difficult to understand and implement. A further aim was to drive standardization of the well collision avoidance rules, process and nomenclature throughout the industry. Standardisation improves efficiency and reduces implementation errors.

The consequences of an unplanned intersection with an existing well can range from financial loss to a catastrophic blow-out and loss of life. The process of well collision avoidance involves rules that determine the allowable well separation, the management of the associated directional planning and surveying activities and assurance and verification. The adoption of a particular minimum allowable separation rule, no matter how conservative, does not ensure an acceptably low probability of collision. Many other factors contribute, such as the level of compliance by office and rig personnel with collision avoidance procedures, and the completeness and correctness of the directional database. These factors are all connected.

The material is split into eight sections, each dealing with a critical element in the collision avoidance process. Examples are presented to highlight good implementation practice. This aligned approach will dispel some of the current confusion in the industry over well collision avoidance; improve efficiency when planning and executing wells and build industry focus on the associated collision risks when drilling. The Technical Section is also supporting the current development of API RP78.

This is the first of two papers. The second paper will cover the minimum allowable separation rule and its application, assurance and verification.
Developing Remote Operations Capabilities in the US Land Market
Authors: Huckeby Joshua
Published: March 2017

The development of remote operations work in the US land market has occurred more slowly than in other markets because of resistance to change at the rig site, continually evolving approaches to drilling programs, and significant increases in penetration rates over the past several years. Because the barriers to entry in the US land directional and measurement-while-drilling (MWD) market are low and the accessibility to the wellsite is high, typical risk mitigation and personnel retention aspects of remote operations play a smaller role in the acceptance of remote operations. The decrease in oil prices from late 2014 to 2016 renewed interest in remote operations to reduce cost.

Successful remote operations in the US land market required revising the traditional remote operations model. Several factors remained similar to the established practices, such as efficient communication networks and intelligent backups of these systems, reducing on-site personnel, and establishing dedicated remote operations center (ROC) workstations. Other factors, however, have changed, including staging a single operator at the wellsite to troubleshoot and maintain interpersonal communication, and developing software solutions to enable the remote operator to operate up to four jobs simultaneously at instantaneous penetration rates of more than 1,000 ft/hr (300 m/hr).

A large service company successfully performed more than 140 MWD remote-operations wells in the Midwest/Rocky Mountain area during the first year of remote operation. During implementation, it was discovered that remote operations are less a technical challenge, and more a value challenge requiring buy-in from all stakeholders. In terms of drilling efficiency, the results seen during this project were significant, with one-third fewer trips for MWD failure, as well as significant reductions in MWD downtime while drilling.

This paper discusses the implementation of remote operations, resulting lessons learned, and optimization opportunities. These lessons learned and optimization opportunities include the challenges of integrating remote operations into a ROC and why personnel selection is crucial to the long-term success of remote operations. The paper also describes how the integration of specialists from several disciplines enhances both remote-operations efficiency and customer experience. Finally, it provides a long-term outlook on US land remote-operations development.
Future Workforce Education through Big Data Analysis for Drilling Optimization
Authors: Zhou Y. , Baumgartner T. , Saini G. , Ashok P. , Oort E. van , Isbell M. R. , Trichel D. K.
Published: March 2017

On their continuous quest to improve drilling efficiency, operators are reaching more and more towards the sensor and data-streaming technologies and their powerful data analytics capabilities. For this project, an operator partnered with the drilling automation research group at the University of Texas at Austin to develop a workflow for big data analysis and visualization. The objectives were to maximize the value derived from data, establish an analysis toolkit, and train students on data analytics—a necessary job function of any future drilling engineer. The operator provided data sets, business and technical objectives, and guidance for the project, while a multi-disciplinary group of undergraduate and graduate students piloted an analysis workflow. The students developed methods to: 1) understand and clean the data; 2) structure, combine, and condense information; 3) visualize, benchmark, and interpret the data, as well as derive key performance indicators (KPIs); and 4) automate these processes.

The operator provided data collected from drilling 16 wells in an US unconventional play. The large data sets comprised of un-organized time and depth based information from surface and downhole sensors, daily drilling reports, geological information, etc. Students were trained on specialized software and subsequently curated data into smaller sizes and standard formats.

Students investigated bottom hole assembly (BHA) and directional drilling performance using a combination of auto-generated conventional visuals (e.g., BHA designs, annotated time vs depth curves) and newly developed tools (e.g., tortuosity, 3D well trajectory plots combined with operational data). Methods for ‘push a button' investigations of mechanic specific energy (MSE), vibration, torque and drag were also developed by calculating specific KPIs from the raw measurement data. The analysis work itself coupled with the attempt to improve the workflow processes served as a meaningful and highly effective way to educate students and prepare them to be the "drilling engineers of the future" with proficiency in data analytics.
A real burnout: death due to 2, 4‐Dinitrophenol poisoning
Authors: Bhagwat Milind
Published: March 2017

Deaths after intentional 2,4‐dinitrophenol (DNP) use have been rising over the last decade. Hyperthermia, tachycardia, tachypnoea and diaphoresis are pathognomonic features of DNP overdose. Fatalities are usually seen within 8 h to a few days after ingestion of DNP. However, symptoms such as rapidly increasing body temperature with cardiac arrest can occur earlier. Aggressive fluid resuscitation and controlling hyperthermia is the mainstay of treatment.
Management of Recurrent Carotid Blowout
Authors: Campbell Rebecca , Roberts Daniel , Mazumder Asif , Devanahalli Roopa
Published: March 2017

Carotid blowout is the term used to describe the rupture of extracranial carotid arteries. It is a potentially life threatening complication of head and neck malignancy or its treatment. Here we describe the successful management of a patient with recurrent carotid blowout syndrome.
A cost model with several hydraulic constraints for optimizing in practice a trapezoidal cross section
Authors: Roushangar Kiyoumars , Alami Mohammad Taghi , Nourani Vahid , Nouri Aida
Published: March 2017

Open channel structures are essential to infrastructure networks and expensive to manufacture. Optimizing the design of channel structures can reduce the total cost of a channel's length, including costs of lining, earthwork, and water lost through seepage and evaporation. The present research aims to present various optimization models towards the design of trapezoidal channel cross section. First, a general resistance equation was applied as a constraint. Next, a genetic algorithm (GA) was used to determine the optimal geometry of a trapezoidal channel section based on several parameters, i.e., depth, bottom width, and side slope. Eight different models were proposed and evaluated with no other constraint besides financial cost as well as with a normal depth, flow velocity, Froude number, top width, and by ignoring the cost of seepage. Numerical outcomes obtained by the GA are compared to previous studies in order to determine the most efficient model. Results from a single application indicate that the restriction of depth, velocity, and Froude number can increase the total cost, while restriction of the top width can decrease the cost of the construction. Also, the solution for various example problems incorporating different discharge values and bed slopes caused increase and decrease in cost, respectively.
Two different purification systems at Istanbul-Tuzla and Adana-Kozan, their characterizations
Authors: Yinanç Abdullah
Published: March 2017

In most developed countries, wastewater treatment plants are presently utilizing efficient purification technology meeting the sufficiency requirements of quality and quantity. However, in developing countries, the number of wastewater treatment plants is limited. As a result, the establishment of a connection between the wastewater collection system and wastewater purification plants is increasingly becoming a top priority for researchers. The aim of this article is to analyze wastewater collection and purification systems and establish the links between these two processes. In the present study, the efficiency of the present purification system at the Istanbul-Tuzla and Adana-Kozan plants was investigated with the aim of enhancing their performance. The findings pertaining to the model sewage system revealed a decrease in NH3-N by 20–70%, total nitrogen (T-N) by 25–75%, biological oxygen demand (BOD5) by 50–60%, chemical oxygen demand (COD) by 35–55% and suspended solids (SS) by 55–85%. As a result of studies performed in the Tuzla sewage treatment system, we can confirm that T-N decreased by 50–75%, suspended solid particles by 24–57%, and BOD5 by 34–57%, while 35–55% of COD was removed. Similarly, in the canal exit at Kоzan, BOD5 decreased by 40–55%, COD by 30–50%, SS by 25–45% and T-N by 5–40%.
Comparison of culture-based, vital stain and PMA-qPCR methods for the quantitative detection of viable hookworm ova
Authors: Gyawali P. , Sidhu J. P. S. , Ahmed W. , Jagals P. , Toze S.
Published: March 2017

Accurate quantitative measurement of viable hookworm ova from environmental samples is the key to controlling hookworm re-infections in the endemic regions. In this study, the accuracy of three quantitative detection methods [culture-based, vital stain and propidium monoazide-quantitative polymerase chain reaction (PMA-qPCR)] was evaluated by enumerating 1,000 ± 50 Ancylostoma caninum ova in the laboratory. The culture-based method was able to quantify an average of 397 ± 59 viable hookworm ova. Similarly, vital stain and PMA-qPCR methods quantified 644 ± 87 and 587 ± 91 viable ova, respectively. The numbers of viable ova estimated by the culture-based method were significantly (P < 0.05) lower than vital stain and PMA-qPCR methods. Therefore, both PMA-qPCR and vital stain methods appear to be suitable for the quantitative detection of viable hookworm ova. However, PMA-qPCR would be preferable over the vital stain method in scenarios where ova speciation is needed.
Ethical leadership and followers' taking charge: Trust in, and identification with, leader as mediators
Authors: Lee Kihyun
Published: March 2017

In previous studies researchers have identified several antecedents of followers' taking charge from their leader, but the ethical nature of taking charge has rarely been considered. Drawing on both social exchange theory and social identity theory, I examined the influence of ethical
leadership on followers taking charge through the mediation of trust in leader and identification with leader. Using data obtained from 236 petty officers and their immediate supervisors in the South Korean Navy, I found that both trust in leader and identification with leader fully mediated
the relationship between ethical leadership and followers taking charge. These findings highlight the importance of commitment to the leader (i.e., trust in leader and identification with leader) as a mechanism through which ethical leadership influences positive work outcomes for the organization.
Implications for theory and practice are discussed.
Competing with visible and invisible competitors in flanker tasks
Authors: Zhu Yingying , Zhou Qiang , Dong Ye Xin
Published: March 2017

We conducted 2 studies to investigate whether or not individuals consider a task to be competitive even when their competitors are imagined. We used a 2-choice reaction time task with compatible and incompatible flankers, which was completed by 64 university undergraduates (Mage
= 21.4 years; range: 19–23 years). In Study 1, participants completed their task in both individual and competitive conditions. In Study 2, participants took turns to compete with the experimenter side by side and then in a different room. Results indicated that the joint flanker effect
occurred, whether or not the competitor was visible or invisible. These findings confirm earlier results that interdependency affects people's behavior even in a competitive context, and promote understanding of the basic mechanism underlying competitive action.
Impression management tactics of protégés and mentors' knowledge-sharing behavior
Authors: Wang Zhenyuan , Zhang Huiping , Chen Xi , Duan Yongjia
Published: March 2017

Given its contribution to organizational knowledge management, a mentoring program is considered to be beneficial for knowledge sharing within organizations. However, little is known about how this benefit occurs. Therefore we conducted an empirical study of protégés'
impression management tactics and mentors' knowledge sharing with 209 people employed by organizations in China and obtained the following findings: (a) Protégés' mentor-focused and self-focused tactics were positively related to mentorship quality, whereas their job-focused
tactics were unrelated to mentorship quality; (b) mentorship quality was positively related to the mentors' knowledge-sharing behavior, and (c) the relationship between the protégés' mentor-focused tactics and mentors' knowledge-sharing behavior was mediated by mentorship quality,
as was the relationship between the protégés' self-focused tactics and mentors' behavior. The implications and limitations of the study are discussed, and directions for future research are suggested.
The Middle and Lower Xingu: the response to the crystallization of different temporalities in the production of regional space
Authors: Siqueira Juliana Mota de , Dal’Asta Ana Paula , Amaral Silvana , Escada Maria Isabel Sobral , Monteiro Antônio Miguel V.
Published: March 2017

While the region of the Middle and Lower Xingu has been a protagonist during many episodes of Brazilian history, it remains unknown to a large cross-section of society. Within this perspective, we have revealed some of the different elements responsible for the production of regional space by joining theoretical exercise with empirical, which signifies combining some of the knowledge that has been produced on the region with the discourse of some of the different agents involved in its transformation. Accordingly, the following processes were adopted as markers: colonization, the opening of the Trans-Amazonian, land conflicts and the construction of the Belo Monte Hydroelectric Power Plant. As part of this collective effort, based on interviews with the central institutions (from the First, Second and Third sectors), and with communities from different locations within the region, this article gathers together arguments that contribute to the debate regarding the accumulated processes in the Brazilian Amazon, and particularly in the Middle and Lower Xingu.
LTR-MDTS structure - a structure for multiple dependent time series prediction
Authors: Pecev Predrag , Rackovic Milos
Published: March 2017

The subject of research presented in this paper is to model a neural network structure and appropriate training algorithm that is most suited for multiple dependent time series prediction / deduction. The basic idea is to take advantage of neural networks in solving the problem of prediction of synchronized basketball referees? movement during a basketball action. Presentation of time series stemming from the aforementioned problem, by using traditional Multilayered Perceptron neural networks (MLP), leads to a sort of paradox of backward time lapse effect that certain input and hidden layers nodes have on output nodes that correspond to previous moments in time. This paper describes conducted research and analysis of different methods of overcoming the presented problem. Presented paper is essentially split into two parts. First part gives insight on efforts that are put into training set configuration on standard Multi Layered Perceptron back propagation neural networks, in order to decrease backwards time lapse effects that certain input and hidden layers nodes have on output nodes. Second part of paper focuses on the results that a new neural network structure called LTR - MDTS provides. Foundation of LTR - MDTS design relies on a foundation on standard MLP neural networks with certain, left-to-right synapse removal to eliminate aforementioned backwards time lapse effect on the output nodes.
Modeling the delivery of security advisories and CVEs
Authors: Ruohonen Jukka , Hyrynsalmi Sami , Leppänen Ville
Published: March 2017

This empirical paper models three structural factors that are hypothesized to affect the turnaround times between the publication of security advisories and Common Vulnerabilities and Exposures (CVEs). The three structural factors are: (i) software product age at the time of advisory release; (ii) severity of vulnerabilities coordinated; and (iii) amounts of CVEs referenced in advisories. Although all three factors are observed to provide only limited information for statistically predicting the turnaround times in a dataset comprised of Microsoft, openSUSE, and Ubuntu operating system products, the paper outlines new research directions for better understanding the current problems related to vulnerability coordination.
REST API example generation using Javadoc
Authors: Rantanen Petri
Published: March 2017

Formatting and editing documentation can be a tedious process regardless of how well your documentation templates are made. Especially, keeping the code examples up-to-date can be time-consuming and error-prone. The research presented in this article describes a Javadoc extension that can be used to produce example data in combination with automatically generated API method call examples, and explains how the APIs in our implementation are organized to further ease the automatic documentation process. The primary goal is to make generating method call examples for (RESTful) web services easier. The method has been used in the implementation of a media content analysis service, and the experiences, advantages of using the described approach are discussed in this article. The method allows easier validation and maintenance for the documentation of method usage examples with a downside of an increased workload in the implementation of software components required for the automatic documentation process.
Classification of totally umbilical slant submanifolds of a Kenmotsu manifold
Authors: Uddin Siraj , Ahsan Zafar , Hadi Yaakub
Published: March 2017

The purpose of this paper is to classify totally umbilical slant submanifolds
of a Kenmotsu manifold. We prove that a totally umbilical slant submanifold
M of a Kenmotsu manifold ?M is either invariant or anti-invariant or dimM =
1 or the mean curvature vector H of M lies in the invariant normal
subbundle. Moreover, we find with an example that every totally umbilical
proper slant submanifold is totally geodesic.
Hybrid functions approach for the fractional Riccati differential equation
Authors: Maleknejad Khosrow , Torkzadeh Leila
Published: March 2017

In this paper, we state an efficient method for solving the fractional Riccati
differential equation. This equation plays an important role in modeling the
various phenomena in physics and engineering. Our approach is based on
operational matrices of fractional differential equations with hybrid of
block-pulse functions and Chebyshev polynomials. Convergence of hybrid
functions and error bound of approximation by this basis are discussed.
Implementation of this method is without ambiguity with better accuracy than
its counterpart other approaches. The reliability and efficiency of the
proposed scheme are demonstrated by some numerical experiments.