bluuebunny/crossref_metadata_2025 huggingface dataset:
Ways to Obtain Optimum Power Efficiency of Artificial Lift Installations
Authors: Takacs Gabor
Published: January 2010

Worldwide more than two thirds of the oil wells are placed on some kind of artificial lift, mostly on sucker-rod pumping, ESP, or gas lift. Because of the great number of installations it is extremely important that they operate under optimum conditions. Even small changes in operational efficiencies can significantly increase operational expenditures, so optimization of the energy efficiency has a great impact on profitability of oil production. The presentation deals with establishing the most energy-efficient operation of artificial lift installations. The aim of the optimization is finding the minimum operational costs while producing a prescribed liquid rate from the well, i.e. attaining the maximum power efficiency. Three forms of artificial lifting are studied: sucker-rod pumping, ESP, and gas lifting.

The power efficiency of any artificial lift system is defined by the relation of the useful power used for fluid lifting and the total input power. The useful hydraulic power is defined by the change of potential energy of the produced fluid, while the total input power can be calculated. Analysis of the power flow in rod pumped wells shows that maximum efficiency is reached with the proper combination of pump size, polished rod stroke length, and pumping speed. The installation's power efficiency is primarily determined by the choice of the pumping mode. The power efficiency of ESP installations is shown to reach a maximum when using a motor and a pump with the maximum efficiency while minimizing the power losses in the electric cable. Optimum design of continuous flow gas lift installations involves NODAL analyses and finds the combination of tubing size, injection and wellhead pressures, and flowline size that ensures the minimum compressor power requirements.
Getting the Most Out of Reservoir Surveillance: A Field Case Study
Authors: Ismadi D. , Suthichoti P. , Kabir C. S.
Published: January 2010

This study presents an inception-to-maturity data acquisition philosophy and deriving value from such surveillance. We show that wellhead pressures can be translated to bottomhole condition for many reservoir-engineering calculations during the flow period. While conversion of WHP to BHP is feasible during a flow test, measurements showed that shut-in tests do not lend themselves for such treatment because of rapid heat dissipation of a low-heat-capacity fluid, such as gas. Therefore, we relied upon flow-after-flow tests that were embedded in monthly variable-rate production measurements to obtain average-reservoir pressure and absolute open-flow potential. These average pressures enriched those that were obtained with downhole gauges from shut-in tests for the material-balance analysis. The resultant time-dependent inflow-performance relationship (IPR) and absolute-open-flow potential helped understand well performance. Indeed, evolution of declining IPR slope led to the identification of gradual wellbore blockage in one of the wells completed openhole. Downhole video recording confirmed mechanical issues in two openhole completions.

Production logging showed preferential flow from the upper section of the thick carbonate interval in two wells. However, residual doubts remained about possible flow up the annulus in the openhole/slotted-liner completions. Analytic modeling confirmed that the notion of preferential flow up the annulus is untenable.
Managing Sulphate Reducing Bacteria (SRB) Problem Associated With Produced Water in One of the Oil Fields of Oil India Limited - A Case Study
Authors: Nihalani M.C. , Verma S. , Kumar J. , Dubey H. , Bharali N.K. , Mandal A.K. , Lal B.
Published: January 2010

In OIL, produced water is normally disposed into Alluvium sand reservoirs at shallow depths. While the disposal depths were in the ranges of 500 – 800 m till recent times, current statutory regulations require disposal to be carried out at depths below 1,200 m to ensure minimal risk of upward migration of such disposed water. In most of these disposal wells, injectivity had been found to be comparatively lower and rapid decline in injectivity is observed even after acid / solvent stimulation.

The presence of SRB was confirmed through API RP 38 standard procedure. SRB related corrosion was also observed in formation water handling and processing infrastructure. Solids generated due to high SRB activity along with high oil content and other suspended solids present was the primary cause of rapid decline in injectivity in these deep disposal wells. The entire problem was taken up for detailed study and identification of remedial measures jointly with a reputed microbial laboratory, M/s The Energy and Resources Institute (TERI), New Delhi, India.

Laboratory investigations included identification, characterization and isolation of various strains of SRB using 16S rDNA gene sequencing and designing different media compositions for inoculation and culturing of SRB strains. Microbial diversity of hyper thermophilic SRB in various produced water samples collected from different points were studied in details.

Through this study, suitable bactericides were identified and Minimum Inhibitory Concentration (MIC) optimized using Time Kill Test (TKT) method. The identified biocides were successfully field tested. The entire produced water from the said field is now being safely managed and disposed underground with sustained injectivity of disposal wells. The present paper discusses the results of laboratory findings and detailed field implementation data, for SRB control in the produced water disposal system.
Cement-Sheath Wellbore Integrity for CO2 Injection and Storage Wells
Authors: Takase Koji , Barhate Yogesh , Hashimoto Hiroyuki , Lunkad Siddhartha F.
Published: January 2010

It is critical that CO2 injection and storage wells have wellbore integrity to help prevent leakage of CO2 during the injection period, as well as long-term zonal isolation to sustain the loading conditions of pressure testing, completions, injection, shut-in, and stimulation treatment. This paper highlights the salient engineering design features of planning a successful cementing-job operation for extended-reach drilled (ERD), carbon capture and storage (CCS) wells.

Corrosion in Portland cement caused by carbonic acid is a well-documented phenomenon. CO2 injected into geologic formations for underground storage purposes can be converted into various concentrations of carbonic acid with different levels of pH in the formation water surrounding the well, depending on conditions such as temperature, pressure, and the formation rock chemical components. The use of non-Portland cement is often recommended in harsh environments (pH<4) to help avoid any negative impact on long-term well integrity. In addition, the cement should have long-term mechanical resiliency against the anticipated future loading conditions of pressure testing, completions, injection, shut-in, and stimulation treatment.

A detailed transient wellbore-temperature analysis was carried out for estimating the wellbore and tubular fluid-temperature profiles during the planned well operations. Based on the estimated temperature profiles, wellbore-pressure conditions, and fluid properties, a rigorous cement-sheath mechanical-integrity analysis was performed following a finite-element analysis (FEA) approach. It was found that the use of non-Portland cement alone might not be sufficient for long-term wellbore integrity. Customized non-Portland cement systems were developed with modified mechanical properties to help ensure appropriate mechanically resilient properties for the long life of a CCS well. Comparative FEA with non-Portland cement and mechanically modified non-Portland cement at the top of tail cement and casing shoe for ERD CCS wells is detailed.
Reconciliation—An Inevitable Challenge in Upstream Oil Industry
Authors: Chebiyyam Chandrasekhar
Published: January 2010

Crude oil is measured at different stages of its flow – i.e.., out of the wells, to Crude oil collection, processing, storage and dispatch installations (GGS - Group Gathering Stations, CTF - Central Tank Farms, CTP - Custody Transfer Points), into tanks & pipe lines, either for flow rate or for inventory positions.

It is a common observation in oil industry that no two meters match exactly. In cases such as crude oil transfer from one location to the other, invariably, the dispatching and receipt meters do have a discrepancy, and sometimes by big margins. This is the point where reconciliation steps in. As long as the differences are within a preset limit, normally caused due to known factors like temperature fluctuations, the difference can be acknowledged as an acceptable reconciliation loss but if the difference is large, this could be due to an abnormal cause such as pipeline leakage or pilferage that needs to be attended immediately. Reconciliation between every two nodes of a crude oil flow provides vital information, not only as a daily tally of crude oil but also as a monitoring tool for the overall chain of flow.

Apart from using elaborate Excel worksheets, previous work in this area has been on the development of stand-alone oil accounting systems specific to Refinery boundaries for monitoring reconciliations and mass balance of oil products, and involves considerable costs. This paper analyses the reconciliation aspects specific to upstream oil industry and suggests a mechanism to monitor these differences between any & every two locations of the crude oil flow, using an ERP package as a backbone, at practically no additional cost.
Systematic Surveillance Techniques for a Large Miscible WAG Flood
Authors: Panda Manmath , Nottingham Derek , Lenig David
Published: January 2010

Miscible water-alternating-gas (WAG) flooding has proven to be an attractive enhanced oil recovery (EOR) method the world over. Successful WAG floods can yield 5-20% additional oil recovery over waterflood because of improved microscopic displacement efficiency by the solvent coupled with improving areal and vertical sweep efficiency through the managed-mobility nature of the WAG displacement process.

WAG floods are complex in nature since reduction of residual oil in the pore spaces depends on mass transfer. Maintaining miscibility between the injected gas and the reservoir oil over a large rock volume is challenging. This challenge is more manageable in a small-scale pilot flood or a core flood than a large field implementation. Numerical simulation efforts can provide guidance to designing an optimal flood. However, the field application will often reveal challenges that are not discovered in the pilot stage or by the full field simulation model because the geologic properties and heterogeneity of the reservoir rock is not accurately represented. Sometimes the incomplete understanding of the PVT characteristics, such as fluid interaction and miscibility, or rock properties, such as wettability and capillary pressures, can exacerbate the challenges.

Integrated surveillance of a WAG flood is the only means to determine whether the flood is working efficiently and the planned additional recovery will be delivered. A well implemented surveillance plan allows timely intervention to improve the efficiency of an underperforming WAG flood.

This paper presents a systematic approach for applying EOR surveillance tools and methods in large miscible WAG floods in the Ivishak reservoirs at the Prudhoe Bay and Eileen West End of the North Slope, Alaska. Highlights of these surveillance methods are (1) designed and implemented by a multi- disciplinary team, (2) based on proven theory and corroborated with field data, (3) requires easily obtainable and relatively inexpensive field data and analysis, and (4) applied from fault block down to zone levels. Implementation of these tools has helped to identify efficient flood patterns and areas of poor performance, which then can be modified through infill drilling, well recompletion, or WAG ratio modification to maximize EOR recovery.
Impact of Increasing Anthropogenic CO2 and CH4 Gases Emission on Cooling of the Earth's Climate
Authors: Sorokhtin O. G. , Chilingar G. V. , Khilyuk L. F. , Haroun M. R.
Published: January 2010

The global climate change issue has the highest priority on the current agenda of the World community because of the global warming trend during the 20th Century. Conventional theory of global warming states that heating of atmosphere occurs as a result of accumulation of anthropogenic CO2 and CH4 in the atmosphere. The writers show that rising concentration of CO2 should result in the cooling of climate instead. The methane accumulation has no essential effect on the Earth's climate. Even significant releases of the anthropogenic carbon dioxide into the atmosphere do not change average parameters of the Earth's heat regime and the atmospheric greenhouse effect. Thus, accumulation of small additional amounts of carbon dioxide and methane in the atmosphere as a result of anthropogenic activities has practically no effect on the Earth's climate.
LNG Smart Air Vaporization Technology Applied to Floating Regasification
Authors: Walther Susan
Published: January 2010

Onshore LNG import and regasification terminals face potential environmental, permitting, cost and schedule issues that can be avoided by use of offshore floating LNG regasification units, FSRUs. The regas technology typically used in a FSRU depends on burning gas or utilizing open loop sea water for the source of heat of vaporization. Burning gas has an environmental impact to the air and the cost of consuming gas that could be sold. Using sea water imposes thermal and chemical impact on marine life. LNG Smart® Air Vaporization (SAV) is an alternative technology that transfers heat from ambient air to the LNG which reduces gas usage and air emissions dramatically, uses no sea water and creates no water pollution.

SAV offers the following advantages: Reduced energy consumption – The proprietary air exchange process offers significant reductions in fuel gas use, from 40-100%, depending on ambient conditions, which results in less shrinkage of the LNG needed for vaporization which is potentially an enormous savings for operators.Lower air emissions - With reductions in fuel gas use, SAV reduces emissions levels on the same order of magnitude as the lower fuel gas consumption.Reduced OPEX - Substantial savings can be demonstrated using SAV. With an onshore Gulf of Mexico 1 bcf/day sendout rate facility, using SAV, with natural gas prices at $6 mmbtu, cost savings with a 90% fuel gas reduction is approximately $25,000,000/year over gas fired technology.Easier permitting – The proven air emissions reduction facilitates permitting.Standard components – While SAV and its configuration are proprietary, virtually all operating components are readily available, shortening construction schedules.Industry-Proven: SAV has been installed onshore and the components have been proven offshore in similar service.Applicable to floating units: SAV can be used on new build or converted reinforced membrane, SPB tanks, or Moss spherical LNG carriers. DNV has given Approval in Principle for utilization of SAV on a FSRU.

This paper explains the LNG Smart® Air Vaporization process and its advantages and gives examples of studies done to utilize SAV on various FSRU hull types.
Management of Change, Key Component of an Effective HSE Management System
Authors: Ershaghi Iraj , Gunasekaran D. Chinnappaaraja
Published: January 2010

Optimum placement of in-fill wells in mature fields requires reliable information about reservoir properties, fluid property distribution and the pressure support of aquifer. In this paper the use of production data is examined as a means of identifying sweet spots for infill directional or extended reach wells. In particular, our focus is the use of production data for fractured reservoirs producing from the Monterey Formation. The emphasis has been mapping of reservoir compartments. Using more than 35 years of historical data on the performance of a number of fields, we have completed a study on the sensitivity of well performance to the size and permeability of compartments, support of aquifer and the matrix or microfractures. This approach can help in identifying cluster of wells with similar compartmental features leading to identification of sub-seismic faults and high productivity compartments and can help in designing the incidence angle of the trajectories of new extended reach and directional wells to intersect compartments with high density fracture swarms.
Innovative Kill and Salvage Operation Successfully Completed in Bay of Bengal with No Hse Incidents
Authors: Curtis Bud , Nutt Joe , Elkins Dave , Ahuja Sunil Kumar , Bhatt Sanjay
Published: January 2010

This paper describes the decision-making process and on-the-fly design strategy that paved the way for the successful and incident-free execution of a uniquely engineered kill and salvage operation in the Bay of Bengal. The seven-month project employed a 150 HP Remotely Operated Vehicle (ROV) to successfully secure a storm-damaged well and recover a 217-ton BOP stack from more than 800 ft of water.

The kill and salvage operation was initiated after a late-summer depression that generated surface and subsurface currents as high as 4.5 knots, eventually severed the riser near the BOP stack on the operator’s Sagar Bhushan drillship, which was completing the ONGC G-1-DB well. The unparalleled project overcame numerous technical challenges to unconventionally kill the well via stinger and retrieve the BOP, subsea tree and wellhead, while averting any potentially catastrophic HSE incidents.

The complexity of the operation was underscored with the on-location designing of an unprecedented procedure and specialized tools to kill the well where all post-storm subsurface components, including the BOP stack and drill pipe, were buried and resting horizontally. Practically all of the tools required had to be customized and fabricated on-board either the ROV-deployment vessel or drillship. These included everything from the customized stinger used to kill the well, to the cutters and heavyweight slings needed to raise the BOP stack.

The authors will systematically review the operation and the close communication between the operator and service provider that resulted in the decision to employ the unique kill and salvage procedure.
Use of KCl-Polymer Clouding Out Polyol Drilling Fluid in Combating High Pressure in Deep Exploratory Wells of Assam Field: A Case Study
Authors: Kumar Shyam , Kachari Jnan
Published: January 2010

Use of Low Solids Potassium chloride - Polymer Inhibitive drilling fluids emerged as an answer to minimize drilling related problems arising from sensitive clays and shale such as borehole instability, torque, drag, build up of low gravity solids, bottom hole fill, stuck pipe attributed to clay/shale hydration. Further improvisement of this drilling fluid system has been done by incorporating clouding out Polyol (equivalent to Clouding out Glycol) for enhanced inhibition and borehole stability. In ONGC it is extensively used successfully to drill high tech wells such as high angle /high drift / horizontal wells in development fields. Exploratory wells are mostly being drilled using dispersed drilling fluids to exploit the convenience of achieving higher drilling fluid specific gravity but wash outs have been problematic in Assam Fields especially in deep shale-coal- sand stone alterations.

Penetrating through troublesome shale coal sequence poses formidable challenge in smooth well completion. ONGC Assam Asset after careful selection used KCl-Polymer Clouding Out Polyol drilling fluid in deep exploratory wells in Assam field. Performance of this drilling fluid in providing borehole stability and more importantly attaining and sustaining higher fluid specific gravity in drilling and in combating well activity has been eventually established. More than five deep exploratory wells have been successfully drilled and two are being drilled in critical interval. Out of these activity in three wells have been successfully subdued using this system with high specific gravity up to 1.9 at the time of writing this paper. Further Pilot test has favourably indicated that given opportunity the above fluid will hold satisfactorily to specific gravity 2.0 without pumpability and Barite sagging problem.

Performance of KCl-Polymer Clouding Out Polyol drilling fluid in drilling especially shale coal-sand/shale-sand sequence of deep exploratory wells in Assam field and the benefits derived out of it have been discussed in this paper.
Successful Hydrofracturing Campaign Leads To Commercial Development of Tarapur Field in Gujarat
Authors: Ramanathan V. , Pankaj P. , Susanta P. H. , Dubey S. , Farooqui M. Y. , Chauhan S. P. , Singh P.
Published: January 2010

In today’s challenging world of exploration, Hydro Fracturing (HF) is an important tool in the oilfield arsenal that enables operators to understand the formation potential deliverability. More and more companies today are adopting hydrofracturing as part of the exploration strategy for better quantification of hydrocarbon production. GSPC decided to precisely do this in their Tarapur asset due to very low rates of production post drilling phase.

GSPC has drilled quite a few wells in the Tarapur field which is located near the Ahmedabad city. In order to verify the ultimate producability of these formations, hydraulic fracturing is the most suitable strategy. 6 wells, which showed presence of oil, were chosen as the stimulation candidates for the production enhancement and production potential identification from this field. This project primarily focused on the exploration and development of the Kalol Sand of the Tarapur field.

The entire HF operation consisted of two parts known as the Datafrac and the Main Fracturing Treatment. Datafrac was done to estimate critical formation and fluid parameters such as like fracture closure pressure, Fluid Efficiency and Leakoff Coefficients which all are determined to design the most optimum job for maximizing ultimate recovery. Reservoir transmissibility validation was also performed via the injection test that is done as a part of the Datafrac injection test.

This paper discusses the planning and design processes leading to the successful execution of the hydro frac treatments and the post-stimulation results. The experience and lessons learned during the stimulation treatment design, execution and post-stimulation results will be discussed. Lessons learned from this successful experience are discussed as a way to enhance the benefits from this promising technology that will lead to more successful developments of the exploration wells in India.
Understanding the Distribution Pattern of Prospective Reservoir Facies: A Sequence Stratigraphic Approach for Integrated Characterization of the Tarapur Field; Cambay Basin, India
Authors: Farooqui M. Y. , Ghosh Ujjwal , Shrivastva Chandramani , Shasmal Sudipan , Bora Deepender , Dubey Sharad , Bhadra Sutapa
Published: January 2010

The Cambay Basin in western onshore India has been on production for a long time and most of the easy-to-find reservoir facies are being exploited by different operators. However, the complex setting of the basin provides opportunity for exploration of many other reservoir facies distributed throughout the basin. Tarapur field is located in a relatively lesser understood part of the basin and understanding the distribution pattern of prospective reservoir facies in this field has been a challenge for optimal exploitation of this area.

An integrated approach has been developed to understand the complexity of the reservoir in a sequence stratigraphic framework integrating the geosciences data from different domains. Borehole images, conventional openhole log data, mud log, nuclear magnetic resonance and background geological information have been incorporated and integrated with seismic backdrop to understand the signatures of geological agencies on the formation across different scales which govern the distribution and geometries of the facies.

Different lithofacies were identified with the help of master log and conventional open hole logs, incorporating the finer textural details from borehole images. The artificial neural network methodology helped in properly differentiating the sub-facies and provided a firm basis for extrapolating the facies associations across different wells of the field. The association of these lithofacies and their orientation derived from the dip data revealed the possible assemblages of depositional sub-environments encountered in a single well. Facies assemblages are mainly comprised of silt, shale and coal lithofacies. These are vertically distributed with a specific fining and coarsening upward trends which are in turn inferred in terms of depositional sub-environments. The study reveals different stages of sediment build up and their vertical facies stacking pattern leads to the identification of two parasequences. By extrapolating the interpreted facies model honoring the petrophysical properties in nearby wells, a good control on the conceptual geological model is achieved. Based on facies association analysis, marginal marine sedimentary environment is envisaged. The stacking pattern of facies associations is interpreted in terms of prograding parasequences which are also identified in seismic line validating the conceived depositional model. This sequence stratigraphic framework provides the predictive value to the model for reservoir facies distribution.

Being the first of its kind in the field, this study provides a methodology that aids in the optimization of exploration strategy. The high resolution seismic attribute analysis coupled with the conceptual model would help in locating the new exploration leads.
Flow Pattern Identification Of Gas-Liquid Flow Through Horizontal Annular Geometries
Authors: Osgouei Reza Ettehadi , Ozbayoglu Evren M. , Ozbayoglu Murat A. , Yuksel Ertan
Published: January 2010

Drilling with aerated muds is becoming more often and essentially used while drilling depleted, low pressured and highly fractured formations. One of the major challenges that have to be faced in such operations is the selection of the proper flow rates for gas and liquid phases. Also, estimation of the physical behavior of aerated fluids inside the annulus is another task that needs to be considered. Although flow of two-phase fluids is studied in detailed for pipes, not much is known for annular geometries. This study aims to identify the flow schemes of gasified fluids flowing inside a horizontal annulus. Experiments have been conducted at METU Multiphase Flow Loop using air-water mixtures with various in-situ air and water flow velocities of 0-120 ft/s and 0-10 ft/s, respectively. A digital high speed camera is used for recording each test dynamically for identification of the liquid holdup and flow patterns. A flow pattern map is developed as a function of superficial flow velocities of liquid and gas phases, and the developed map is compared with existing flow pattern maps, such as Beggs & Brill and Taitel & Dukler. Then, a new classification of two-phase flow patterns by using discriminant analysis is proposed. Observed two-phase flow patterns are: Smooth Stratified (SS), Wavy Stratified (WS), Plug (PL), Slug (SL), Churn (CH), Wavy Annular (WA), Dispersed Annular (DA) and Dispersed Bubbles (DB). When developed flow pattern map is compared with existing flow pattern maps used for pipes, it is observed that existing flow patterns are not accurate for horizontal annular geometries.
Effects of Technology Immersion on Teachers' Growth in Technology Competency, Ideology, and Practices
Authors: Shapley Kelly , Sheehan Daniel , Maloney Catherine , Caranikas-Walker Fanny
Published: January 2010

In the study of the Technology Immersion model, high-need middle schools were “immersed” in technology by providing laptops for each teacher and student, instructional and learning resources, professional development, and technical and pedagogical support. This article reports third-year findings for the teacher component of the theory-driven evaluation. Using hierarchical linear modeling (HLM) to analyze longitudinal survey data, we found that Technology Immersion has a statistically significant effect on teachers' growth rate for technology knowledge and skills, ideological affiliations with technology integration and learner-centered instruction, and the frequency of class activities involving technology. Treatment teachers' technical proficiency and their school's innovative culture, ongoing professional development, and parent/community support predicted teachers' higher classroom immersion. The authors discuss the viability of the Technology Immersion model and implications for technology integration in classrooms.
Factors Influencing Pupils' Acceptance of an E-Learning System for Secondary Schools
Authors: Friedrich Helmut Felix , Hron Aemilian
Published: January 2010

The present study aims at investigating which factors are significant for pupils' acceptance of an E-Learning system introduced into secondary schools. The E-Learning system consisted of interactive learning modules for several school subjects and a Learning Management System (LMS). Research on IT acceptance and attitudes guided the specification of independent variables as predictors of acceptance. Survey data were collected from 125 pupils from 8 German high schools in January and July 2005. Results from a three-step hierarchical regression reveal that perceived usefulness was a significant positive predictor of pupils' acceptance, with perceived usefulness of the LMS having the greatest weight. Computer related attitude, self-efficacy, and gender had negligible or no influence on acceptance. The final regression model accounted for approximately 51% of the variance in the outcome measure. The findings indicate the critical importance of perceived usefulness in predicting pupils' acceptance of the E-Learning system, as is likewise known from acceptance research on IT at the work place.
Tablet Personal Computer Integration in Higher Education: Applying the Unified Theory of Acceptance and use Technology Model to Understand Supporting Factors
Authors: Moran Mark , Hawkes Mark , Gayar Omar El
Published: January 2010

Many educational institutions have implemented ubiquitous or required laptop, notebook, or tablet personal computing programs for their students. Yet, limited evidence exists to validate integration and acceptance of the technology among student populations. This research examines student acceptance of mobile computing devices using a modification of the “Unified Theory of Acceptance and Use of Technology” (UTAUT) recently developed by leading researchers in the technology acceptance field. The objective of the study is to identify the variance of selected acceptance elements that contribute to the overall behavioral intent to use Tablet PCs (TPC). These outcomes are then used as a means to forecast, explain, and improve integration of the technology in the higher education context. The research also contributes to UTAUT's theoretical validity and empirical applicability and to the management of information technology (IT) based initiatives in education.
Differential Effects of Web-Based and Paper-Based Administration of Questionnaire Research Instruments in Authentic Contexts-of-Use
Authors: Hardré Patricia L. , Crowson H. Michael , Xie Kui
Published: January 2010

Questionnaire instruments are routinely translated to digital administration systems; however, few studies have compared the differential effects of these administrative methods, and fewer yet in authentic contexts-of-use. In this study, 326 university students were randomly assigned to one of two administration conditions, paper-based (PBA) or web-based (WBA), and given a set of questionnaires. Instructions were to complete the instruments in an environment of their choice, and data included reporting context characteristics. Outcomes of interest included data quality and participant affect—WBA showing a slightly higher percent of data loss and lower overall time to complete; PBA producing higher overall mean scores across measures, greater variability in responses, and higher positive affect for responding. Administration methods showed no difference on internal consistency of subscales, positive-response bias, or strength of interscale correlations. Contexts-of-use included involvement in television viewing, conversation, and other activities, raising questions about the accuracy and independence of survey responses completed in independently-chosen, uncontrolled contexts. The qualitative data demonstrated longer responses in WBA than PBA, but little difference in type and clarity of responses.
Influence of Particle Size, Reactor Temperature and Gas Phase Reactions on Fast Pyrolysis of Beech Wood
Authors: Chen Li , Dupont Capucine , Salvador Sylvain , Boissonnet Guillaume , Schweich Daniel
Published: January 2010

In the present work, a drop tube reactor (DTR) and a horizontal tubular reactor (HTR) were used to study the pyrolysis behaviour of beech wood particles of different sizes under the conditions encountered in industrial fluidized bed gasifiers, namely high external heat flux (105  106 W.m-2) and high temperature (800  1000°C). The influence of the reactor temperature (800 and 950°C), of particle size (from 350 µm to 6 mm), and of gas residence time (from 1 to 10 s) were examined. Under the explored conditions, when pyrolysis is finished, more than 80 wt.% of virgin wood is converted into gas and less than 13 wt.% remains in solid. In the gas phase, CO is the main gaseous product (50 wt.% of virgin wood), followed by H2 (molar ratios of H2/CO are between 0.35 to 0.55), H2O, CO2 and CH4. Species C2H2, C2H4, C2H6 and C6H6 are present in much lower amounts. The increase of temperature increases the rate of solid devolatilization and favours the cracking reactions of hydrocarbons. The increase of particle size increases the required time for completing pyrolysis. Meanwhile, the results obtained at 950°C show that the final products distribution at the end of pyrolysis is almost the same for the particles between 350 and 800 µm. The increase of the particle size from 800 µm to 6 mm seems to have some influence on the final products distribution. The gas phase reactions mainly change the yields of light hydrocarbons and H2: the increase of gas residence time favours the cracking reactions of hydrocarbons and thus leads to a higher H2 yield.
Gas Hold-Up and Mass Transfer in Three Geometrically Similar Internal Loop Airlift Reactors Using Newtonian Fluids
Authors: Cerri Marcel Otavio , Policarpo Lucas Makrakis , Badino Alberto Colli
Published: January 2010

Global gas hold-up and volumetric oxygen transfer coefficient (kLa) were evaluated in three internal-loop airlift reactors (ALR) with different working volumes (2, 5, and 10 dm3) and similar geometric configuration utilizing eight Newtonian fluids. Superficial gas velocity in the riser (UGR) was ranged from 0 to 0.112 ms-1. The effects of the superficial gas velocity (UGR) and liquid viscosity had contrary effects on kLa. However, they presented the same order of magnitude showing that the viscosity effect on the oxygen mass transfer cannot be neglected. Two correlations based on dimensional analysis relating global gas hold-up and kLa to the geometric parameters, physical properties of the fluids, and operational conditions were proposed. Very good fittings between calculated and experimental data of and kLa were obtained. The influence of the internal diameter of the reactor on kLa was considered positive showing that in large-scale reactors an appropriate oxygen transfer can be reached under smaller aeration conditions, due to higher internal diameter.
Association between Local External Gamma Rays and Frequency of Cancer in Babol-Iran
Authors: Monfared Ali Shabestani , Hajian Karimollah , Hosseini Reza , Nasir Akbar
Published: January 2010

Introduction

The effect of natural background radiation on Cancer is still challenging. The investigation of association between external gamma rays and Cancer was the main goal of study.

Materials & Methods

External Gamma rays were measured using a radiation survey meter in 184 urban and rural health centers to estimate the exposure to the population in residential areas of Babol. The dose distribution map was compared to the 5 years radiation induced cancer incidence data from cancer registry center in north part of Iran.

Results

Results showed that although the external gamma ray level in Babol is nearly equal to the average natural background radiation in the world, there is a relatively weak inverse association between local external gamma ray and incidence of Cancer [Correlation coefficient = −0.43, (p<0.01)].

Conclusion

This finding might be due to the inhibition of cancer induction following exposure to the low doses of ionizing radiation and probably can be a confirmation of radiation hormesis. However, due to some uncertainties, the conclusion should be interpreted with caution. Further national and international studies are suggested.
Renoprotective effect of calcium channel blockers
Authors: Dimkovic Nada , Dimkovic Sinisa
Published: January 2010

The advancing chronic renal failure is at most the consequence of secondary haemodynamic and metabolic factors as intraglomerular hypertension and glomerular hypertrophy. Although tight blood pressure control is the major preventive mechanism for progressive renal failure, ACE inhibitors and angiotensin receptor blockers have some other renoprotective mechanisms beyond the blood pressure control. That is why these two groups of antihypertensive drugs traditionally have advantages in treating renal patients especially those with proteinuria over 400-1000 mg/day. Even if earlier experimental studies have shown renoprotective effect of calcium channel blockers, later clinical studies did not prove that calcium channel blockers have any advantages in renal protection over ACE inhibitors given as monotherapy or in combination with ACE inhibitors. It was explained by action of calcium channel blockers on afferent but not on efferent glomerular arterioles; a well known mechanism that leads to intraglomerular hypertension. New generations of dihydropiridine calcium channel blockers can dilate even efferent arterioles not causing unfavorable haemodynamic disturbances. This finding was confirmed in clinical studies which showed that renoprotection established by calcium channel blockers was not inferior to that of ACE inhibitors and that calcium channel blockers and ACE inhibitors have additive effect on renoprotection. Newer generation of dihydropiridine calcium channel blockers seem to offer more therapeutic possibilities in renoprotection by their dual action on afferent and efferent glomerular arterioles and, possibly by other effects beyond the blood pressure control.
Analysis of the performance of the ship steam boiler using simulation
Authors: Dvornik Josko , Tireli Enco , Dvornik Srdjan
Published: January 2010

The aim of this paper is to demonstrate the successful application of system dynamics simulation modelling at investigating performance dynamics of the ship steam boiler. Ship steam boiler is a complex non-linear system which needs to be systematically investigated as a unit consisting of a number of subsystems and elements, which are linked by cause-effect feedback loops, both within the system and with the relevant surrounding. In this paper the authors will present the efficient application of scientific methods for the research of complex dynamic systems called qualitative and quantitative simulation system dynamics methodology, which will allow for production and use of higher number and kinds of simulation models of the observed elements, and finally allow for the continuous computer simulation, which will contribute to acquisition of new information about the non-linear character of performance dynamics of ship steam boilers in the process of designing and education. Ship steam boiler will be presented in POWERSIM simulation language in mental-verbal, structural, and mathematical computer models.
Optimal temperatures and maximum power output of a complex system with linear phenomenological heat transfer law
Authors: Chen Lingen , Li Jun , Sun Fengrui
Published: January 2010

A complex system including several heat reservoirs, finite thermal capacity subsystems with different temperatures and a transformer (heat engine or refrigerator) with linear phenomenological heat transfer law [q ? ?(T -1)] is studied by using finite time thermodynamics. The optimal temperatures of the subsystems and the transformer and the maximum power output (or the minimum power needed) of the system are obtained.
Analysis of photothermal response of thin solid films by analogy with passive linear electric networks
Authors: Galovic Slobodanka , Soskic Zlatan , Popovic Marica
Published: January 2010

The paper presents conditions that should be met in order to make the photothermal induced temperature variations of a solid sample analogous to the voltage variations of the electric network with passive linear elements. Further analysis shows that such analogy enhances experimental determination of the thermal properties of thin solid layers by photothermal frequency method.
Natural convection heat transfer in a partially divided trapezoidal enclosure
Authors: Arici Mehmet , Şahin Birol
Published: January 2010

Natural convection heat transfer in a partially divided trapezoidal enclosure is studied numerically using the control volume method. Summer and winter conditions are separately examined by imposing regarding thermal boundary conditions. A horizontal divider included and its two different placements are considered. It is shown that heat transfer results are not significantly altered by the presence of the divider for summer condition. For winter condition, on the other hand, decrement in heat loss and effect on the flow and the temperature fields by the presence and the placement of the divider are observed, respectively. As a horizontal divider is placed to oppose buoyancy, the flow strength becomes weaker and formation of two separate levels of temperature uniformity occurs. As the divider is placed to assist buoyancy, the flow gets stronger and tends to form relatively uniform temperature field within whole enclosure.
Pedagogisation as a conceptual framework for understanding modern education
Authors: Vujisic-Zivkovic Natasa
Published: January 2010

Pedagogisation is a theoretical construct, an interpretative category, means used by researchers in order to explain certain forms and trends in educational practice. This concept proved to be fruitful in identifying the omnipresent orientation to search for solutions for broader social and economic problems in education. The goal of this paper is critical reconsideration of different meanings of pedagogisation as a possible conceptual framework for understanding modern education, and shedding light on the phenomenon of pedagogisation in the historical and contemporary context. From the perspective of pedagogical historiography, pedagogisation is observed as a kind of dark shadow of modernisation processes in the society and education and the paper discusses two of its poles: 'pedagogisation of childhood world', which assumes observing children's world thorough pedagogical prism, and 'towards school' oriented concept of pedagogisation, manifested through tendency to translate broader social issues in teaching units of formal education. On the other hand, we presented the implications of pedagogisation in contemporary education from the viewpoint of critical pedagogical theory, in which pedagogisation obtained the position of a conceptual framework, which was used to answer the question of what remains behind education when it is relieved of the burden of solving social issues, that is, the always current question of the role of education in society development.
Students' assessment of family functionality and attendance of religious instruction in school
Authors: Zukovic Sladjana
Published: January 2010

The goal of the research presented in this paper was to study the relations between students' estimation of the real and desired state of family functionality and attendance of religious instruction in school. The results obtained on the sample of 421 secondary school students of the third grade, who opted for attending religious instruction at the beginning of this level of schooling (263 students) or for attending the alternative elective subject - civic education (158 students). For assessing relevant dimensions of the real and desired state of family system functionality, the standardized instruments were used - FACES III (cohesion and flexibility of the family) and F-COPES (strategies of family's overcoming of problems). For collecting data on sociodemographic characteristics of respondents and their families, as well as the assessment of effects of attending religious instruction on the family, we used the Student Questionnaire, constructed for the purposes of this research. Based on the analysis of the obtained results, we reached the conclusion that in certain aspects there are differences in students' assessment of the real and desired state of family functionality, depending on the elective subject they attend, as well as that it can be stated with great probability that some of the measured family characteristics are significantly correlated with the effects of religious instruction on students and their family as a whole.
Short-Term Administrations of a Combination of Anti–LFA-1 and Anti-CD154 Monoclonal Antibodies Induce Tolerance to Neonatal Porcine Islet Xenografts in Mice
Authors: Arefanian Hossein , Tredget Eric B. , Rajotte Ray V. , Gill Ron G. , Korbutt Gregory S. , Rayat Gina R.
Published: January 2010

OBJECTIVE

The objective of this study was to determine whether tolerance to neonatal porcine islet (NPI) xenografts could be achieved by short-term administrations of anti–LFA-1 and anti-CD154 monoclonal antibodies (mAbs).

RESEARCH DESIGN AND METHODS

Diabetic B6 mice received NPI transplants and short-term injections of combined anti–LFA-1 and anti-CD154 mAbs. Mice with long-term islet graft function were treated with depleting anti-CD25 mAb or re-transplanted with a second-party NPI. At the end of the study, grafts from mice with long-term islet function were examined. Their spleen cells were characterized and used for in vitro proliferation and adoptive transfer studies.

RESULTS

All mAb-treated NPI recipients maintained normoglycemia for >100 days post-transplantation. Only 5 of 50 mice rejected their grafts before 300 days post-transplantation. Intact islets, foxp3+ immune cells, as well as interleukin (IL)-10 and transforming growth factor (TGF)-β regulatory cytokine transcripts were detected in the NPI xenografts from tolerant mice. A higher percentage of CD4+ T-cell population from these mice expressed regulatory markers, suggesting that tolerance to NPI xenografts may be mediated by T regulatory cells. This was confirmed when tolerant mice treated with depleting anti-CD25 mAb became diabetic. Lymphocytes from tolerant mice inhibited the proliferation of lymphocytes from B6 mice immunized with porcine cells and they displayed limited proliferation when adoptively transferred. All protected B6 mice transplanted with a second-party NPI xenograft maintained long-term normoglycemia even after removal of the first NPI graft-bearing kidney.

CONCLUSIONS

These results demonstrate that tolerance to NPI xenografts can be achieved by transient administrations of combined anti–LFA-1 and anti-CD154 mAb therapy.