bluuebunny/crossref_metadata_2025 huggingface dataset:
Pore Pressure Prediction Using Seismic Velocities for Deepwater High Temperature- High Pressure Well in Offshore Krishna Godavari Basin, India
Authors: Chatterjee Avirup , Mondal Samit , Basu Pramit , Patel B. K.
Published: March 2012

Velocities derived from the seismic data provide indirect estimation of the formation pressure prior to drilling. The uncertainties in velocity estimation increase with the geological complexity and depth which in turn amplify the margin of error in the pore pressure prediction. Such uncertainties can be reduced by adopting suitable velocity to carry out predrill pore pressure prediction. Several advanced techniques for velocity analysis have been used in this study with varying degree of confidence for pore pressure estimation in a deep water HTHP well. The well was designed to drill to a depth of 5000 m with an overpressured Cretaceous clastic sediment column of 2000 m before reaching the reservoir (water depth 600m, maximum prognosed pressure ~11,000 psi and temperature ~190°C).

In deepwater Krishna Godavari basin, the conventional seismic velocity (Handpicked and stacking velocities) based pore pressure prediction resulted in considerable uncertainties in the older Cretaceous sediments as seen in the earlier drilled wells. This called for an advanced velocity analysis (AVO based and Inversion velocities) to reduce the margin of uncertainties for this study well. Such analysis added values to our understanding of the impedance contrast, temporal and spatial variations of velocity in terms of reservoir and non reservoir inter-relationship. A definitive predrill pore pressure curve, taking into account these geological and geophysical factors was the best estimate for well planning. HTHP well drilling challenges can be constrained by depth of top of overpressure, narrow pore-frac window and large ESD-ECD variations due to high temperature gradient. The definitive pore pressure curve catered to limiting all the three critical parameters as comparison with the post drill pore pressure analysis showed a variation of ±0.5ppg. Future deepwater HTHP prospects can be planned by the similar work flow as the drilling experience of this prospect was satisfactory.
Experimental Study of Sea Line Pigging in Unsteady State Two-Phase Flow
Authors: Davoudi M. , Khorrami Z. , Khoramdel I.
Published: March 2012

The main objective of this study is to thoroughly investigate and comparing empirical and simulation results for two-phase flow during the pigging in hilly-terrain pipelines to calculate the amount of slug versus pig velocity. The high slug volume was received in slug catcher after pigging operation of sea lines related to phases 4 and 5 gas plant located in south pars gas field, south of Iran, caused liquid carry over to down stream units and total plant shut down. Beside of liquid level in slug catcher, some parameters such as liquid bottle level, and slug catcher pressure were measured during pigging time process. The results showed that during pigging process, the liquid slug volume was increased from 2100 (m3) to 4100 (m3) by decreasing the gas flow rate from 700 (ton/hr) down to 400 (ton/hr) during pigging operation. The experimental data were compared with the results of mathematical modeling of process by using SPS dynamic simulation software. The relative errors between experimental data and mathematical modeling of the process were 23.8% and 9.1% for gas flow rates of 700 (ton/hr) and 400 (ton/hr), respectively.
Dynamic Simulation for Optimising Pigging Frequency for Dewaxing
Authors: Bansal Rajeev , Ravishankar B , Sharma S S , Afzal Kamran
Published: March 2012

The presence of paraffin in crude oil often leads to wax deposition in pipelines when temperatures reach below Wax appearance temperatures. It is possible to simulate the wax build up using thermodynamic and kinetic/deposition models for estimating wax deposition with varied degree of accuracy. The most popular remediation technique for wax removal is direct mechanical cleaning using pigs as these are generally cheaper than chemical inhibitors. The pigging frequency is mostly determined using thumb rules and operating experience. Correct pigging frequency is essential to avoid significant wax build-up in pipeline that may lead to plugging or stuck pig. This becomes more acute in subsea lines where insufficient well head pressures driving the pig may not scrap out the wax plug ahead of pig. This can increase to downtime and can lead to expensive pipeline repair.

In Mumbai offshore pigging is most common method of wax removal in well fluid lines. In this paper a simulation model using dynamic simulator for predicting daily wax build-up and pigging shall be discussed. The model is based on the actual pipeline condition, fluid parameters and pigging data. Extensive lab studies on actual comingled well fluid samples from platform have been carried out for capturing the Fluid & Wax properties.

The model has been used to run what if scenarios by varying the pigging frequency for the pipelines. The impact of ambient temperature or increase in gas (lift gas) in well fluid on pigging has been studied. Sensitivity studies have been carried out for various parameters like wax plug friction, bypass opening, change in well fluid parameters, etc.
HPHT Gas Well Cementing Complications and its Effect on Casing Collapse Resistance
Authors: Yuan Zhaoguang , Schubert Jerome , Teodoriu Catalin , Gardoni Paolo
Published: March 2012

The failure probability of casing collapse is high in HPHT gas wells because of the cementing complications and the operational environment. In the life of a well, the cement sheath not only provides zonal isolation but also supports casing and increases casing collapse resistance. Due to the high temperature high pressure conditions, the cement sheath plays a more important role in maintaining wellbore integrity. During the production process in HPHT gas wells, the pressure differential inside the casing and the surrounding formation is larger than the conventional wells, this presents a greater challenge to the casing integrity.

Casing eccentricity, cement voids and cement channels usually are cementing complications in HPHT gas wells. Pore-pressure was also considered in this study. In the analysis, the finite element method was used and 2D simulation model was built to study the effect of cementing complications on casing collapse resistance. In the study, two cement systems, brittle cement system and elastic cement system, were used to analyze the effect of the cement property on the casing collapse resistance. In the sensitivity analysis, void location, void size and shape, casing eccentricity, pore pressure, casing internal pressure, horizontal stress, cement Young’s Modulus, cement Poisson ratio, hole diameter, and formation temperature were considered to study their effect on casing collapse resistance.

The results showed that an improvement of collapse resistance of 12% is observed in various conditions in elastic cement system. Casing collapse resistance is very sensitive to void location, cement Poisson’s Ratio, cement Young’s Modulus, and pore-pressure. Casing eccentricity and voids shape have minor effect on the casing collapse resistance. Simultaneous cement channeling and casing eccentricity is the worst case scenario in casing collapse resistance.

This study gives a better understanding of casing collapse failure in HPHT gas wells and helps improve cement and casing design to maintain wellbore integrity that can be expected to last for the life of the well.
Application of Self-Diverting Acid System for Stimulation of Multilayered Wells in Carbonate Reservoir: A Case Study
Authors: Sarma Dilip Kumar , Rao Y R , Mandal B , Bhargava P K
Published: March 2012

During acidization of multilayered wells, major portion of the acids preferably enter into high permeable layers bypassing the low permeable layers. To combat the challenge a self-diverting acid (SDA) was developed with conventional chemicals for effective stimulation of all the layers. The technique involves a stable retarded acid system, a plain acid, a viscous diversion system and a chemical formulation for taking care of wettability issue of the formation rock. Descaling and formation preconditioning were also included for effective treatment and flow back. Two polymers were evaluated in the laboratory for customization of diversion system. The concentration of polymer was optimized to achieve the optimum viscosity required to divert the acid based on the reservoir properties and the flow back after the treatment.

The technique has been implemented in 31 multilayered wells of Mumbai High, a major offshore oil field in India, consists of multilayered carbonate reservoirs, with substantial heterogeneities among the layers. All the candidates were selected with MDT approach. Well specific treatment designs were carried out considering the damage mechanism, reservoir properties and well completions. The treatments were designed in multiple stages of preflush, acids, diversion systems and postflush. The chemical formulation for wettability alteration was used in selected wells.

The placement was carried out by bull-heading and real time treatment plots were recorded in each job. The treatment plots indicate effective acid exposure and uniform stimulation among the layers. Post treatment analysis indicated significant oil gain. This paper will cover the critical areas of stimulation in multilayered wells, details of the SDA technique, treatment methodology, design and post treatment evaluation.
Continuous Improvement in Drilling with Rotary Steerable System in Mumbai High Field
Authors: Soni S. C , Bhargava Ajay , Desai Amit B , Kumar Rakesh , Suryadi Hendrik
Published: March 2012

Application of Rotary Steerable System(RSS) drilling in one of the biggest Indian offshore field, Mumbai High was driven by the increasing difficulties associated with directional drilling by mud motor technology, especially in Extended Reach wells. ONGC has focused largely on finding economic and competitive ways of exploiting the mature and depleted field. Rotary Steerable System provides the opportunity to reach farthest unexploited subsurface targets without adding new platforms with significant improvement in drilling performance and challenging subsurface objectives.

Since first application in the year 2004, RSS has successfully overcome the drilling challenges & problems, especially in 12¼"section, deliver improvement in drilling time. The paper will discuss in detail, each step of continuous improvement in RSS applications & operations, field specific bit design, drill string, fluid system modifications and real time drilling optimization during the last seven years. The actual result on overall directional drilling efficiency enhancement after implementation of each optimization methodology is also discussed.

The discussion covers some unique RSS applications in Mumbai High Fields such as:, drilling top hole 17-1/2" section to complete the well in required hole size, drilling 8-1/2" multilateral section including open hole sidetrack, drilling 6" with RSS & pro-active geo-steering technologies keeping the well in good reservoir with high penetration rate and long horizontal drift. Based on the field results and performance analysis it is concluded that continuous up gradation of mud system, bit design, string design and real time monitoring with proven technology of RSS lead to successful completion of high drift wells.
Fracture Assisted Sandstone Acidizing, Alternative Approach To Increase Production in Tight Sandstone Reservoir
Authors: Gunawan Haris , Susanto Hermawan , Widyantoro Barkah , Noguera Jose
Published: March 2012

The proven and most suitable stimulation technology to increase production in a tight sandstone formation is hydraulic fracturing. The hydraulic fracturing treatment will create a fracture and then keep it open by proppant, hence a conductive path allowing more oil and gas to be produced. Hydraulic fracturing operations in an offshore environment are sometimes considered as a costly solution and non-economic. An alternative economic solution, Fracture Assisted Sandstone Acidizing (FASSA), was evaluated. Sandstone acidizing is a method to increase oil production, by injection of compatible acid system at matrix rate, below the formation fracture gradient. This stimulation method is most suitable to remove near wellbore damage in medium-high formation permeability. To improve the effectiveness of the acid treatment in tight sandstone reservoir, a hydraulic fracture was created prior to the sandstone acidizing. Besides removing the near wellbore damage, the acid is expected to react with fracture face in sandstone and create a conductive path for oil to flow. Four successful jobs have been performed to date. This paper will describe planning, process, acid treatment selection, operation summary, and evaluation of success or failure of the treatment. In the future we also propose to perform similar treatments for a tight reservoir without having to pull out the existing completion.
Decision Making in Upstream Oil and Gas Industry - An Integrated Approach
Authors: Deore Prakash
Published: March 2012

The research presented in this paper is based on existing decision theory and literature used in the oil and gas industry. The outcomes of the study would provides an evidence that in oil and gas industry there is a strong linkage between the use of integrated decision making approach, informed decisions and hence good process performance. The existing state of decision making in industry is being limited, in terms of both user and its functionality per se.

Also it is commonly acknowledged that organizations have not really used as it was predicted at its conception. Allthough, there are initiatives under smart oilfield programs, where organizations are considering integrated approaches of decision making, and that would be the way forward to optimize process time, efforts and cost.

The bottleneck for lower attention to integrated approach is that there is no study or experience captured on improved performance metrics or parameters. Some of the recent surveys indicated from different industries, that making use of integrated approach, efficient tools and standard methodologies in decision making process can help individuals and organizations to meet their objectives.

Initial part of this study introduces decision making and its standard process flow componants. Subsequent part of the study elaborates existing state of decision making in the industry, and integrated decision making approach to new investment analysis in upstream. Lastly, it ascertains the importance of process, method, tool selection for making an informed decision and further optimization.
Well Placement Optimization in a Mature Carbonate Waterflood using Streamline-based Quality Maps
Authors: Taware Satyajit , Park Han-Young , Datta-Gupta Akhil , Bhattacharya Shyamal , Tomar A. K. , Kumar M. , Rao H. S.
Published: March 2012

The placement of infill producers and injectors is an important aspect in the overall development strategy of any field and is particularly challenging for mature fields with high levels of water-cut. Previous screening approaches based upon static reservoir quality maps have limited applicability as these do not account for the drainage and swept volumes from existing wells. In contrast, direct application of formal optimization methods such as evolutionary algorithms and adjoint-based methods to high resolution geologic models may better represent reservoir dynamics but can be complex to implement or computationally prohibitive.

We propose a novel method for well placement optimization that relies on streamlines which represents the flow paths in the reservoir and the time of flight which represents the travel time of fluids along streamlines. Specifically, the streamline time of flight from the injectors provides swept volumes for injectors whereas streamline time of flight from producers gives drainage volumes for producers. These quantities can be effectively combined to a ‘total time of flight’ to locate the potential regions of unswept and undrained oil in the reservoir. Our approach utilizes a dynamic measure based on the total streamline time of flight combined with static parameters to identify potential locations for infill drilling. Areas having high value of the dynamic measure (sweet spots) are both poorly drained and poorly swept, making them attractive for drilling infill wells.

We show the power and utility of our proposed method on a mature offshore carbonate field in western India. The simulation model was history matched using a hierarchical history matching approach that follows a sequence of calibrations from global to local parameters in coarsened and fine scales. Using our proposed method on the history matched model we obtained a dynamic measure map highlighting areas suitable for drilling infill wells. Finally, we compared the performance of infill wells located using the dynamic measure map with wells located using traditional well placement techniques, for example, oil saturation map from simulation. Our proposed method consistently outperforms the traditional approaches. Subsequent field infill drilling in the field has validated our approach.
Introduction of FPSO Technology in ONGC: Strategy & Lessons Being Learnt
Authors: Malik Naresh , Das P. , Sengupta T. K.
Published: March 2012

ONGC’s offshore operations - Application of Floating production systems

ONGC’s major share of oil & gas production comes from its offshore fields in water depths ranging upto 100m with facilities mainly confined to fixed wellhead platforms with dry trees, fixed processing platforms and subsea pipelines. This approach is economically viable only for fields having high production potential and long field life, being high capital intensive. ONGC has discovered few offshore marginal fields located at considerable distance from existing processing facilities with peak production potential of the order of 25000-50,000 BOPD and short production plateau period. Development of these fields with fixed platform and pipeline architecture will not be cost effective. Further Fixed platforms have limitations in terms of water depth and are not suitable for the discovered fields in the deeper waters. Therefore, ONGC started examining the development with alternative technologies like FPSO, MOPU, FSO/FPU combination, etc. for last couple of years.

Each of the alternative solution has its own advantages over the other. Decision to select a particular development option depends on many aspects besides technology and economic viability. The decision has to be weighed on considerations like company’s strategy to own asset/facility or to take asset/facility on hire, operational philosophy (by company itself or hire from contractor), company’s experience / position on learning curve for the selected technology. The decision process is necessarily iterative and involves tradeoffs.

The first technology considered for development of a marginal offshore field is by deploying a hired FPSO for processing and export of hydrocarbons. All possible options were examined and weighed against each other wherein hired FPSO approach was found to be most attractive. The exercise carried out for one field (X) has established that FPSO as a viable alternative for consideration for development of marginal fields offshore. While the contract for hiring FPSO for X field has been awarded and FPSO is expected to be mobilized in Dec 2012, ONGC requires another FPSO for Y field development.

The paper will discuss the Technological & Contractual issues, the acquisition strategy and the lessons learnt in hiring a FPSO for development of marginal fields in western offshore and to master the technologies to regain confidence to operate in deep water in east coast in future.
ONGC’s C-Series Trunk Pipeline Commissioning
Authors: Kumar P. V. , Charyulu S. K.
Published: March 2012

The C-Series marginal gas field in Tapti is located approx. 60 KM West of Daman. Under Phase-I implementation, four unmanned well platforms namely C-22P, C-24P, C-39-P1 & C-39-PA have been installed. C-39-PA is the farthest platform and connected to C-24P via 60 kms of 22" and C-24P to NQG process platform via 115 kms of 28" sub-sea pipelines. Gas from NQG is transported to Uran after processing.

Pipeline is very long sub-sea pipeline bearing a very typical profile with un-favorable contour having multiple sources, having a reverse profile with C-series platforms at a shallow depth of 19-23m and the receiving process platform NQG at a depth of about 64 m. The gas, condensate and liquid production profile makes this pipeline more critical during regular production and having severe surging problems.

Dewatering and commissioning of the pipeline with a conventional approach to launch the pig train from the launcher at C-24 well platform and receiving the pig train at NQG receiver was considered initially. The pipeline filled with 60 thousand cubic meters of treated water. If pigging is done conventionally huge surges are anticipated at NQG, may cause process upset and may lead to shutdown of the process complex. Because of this a different way of launching the pig from receiver end i.e., (NQG), deeper pipeline profile and receiving the pig at C-24 platform, a shallower pipeline to ensure safe and practicable operation. The pigging was done successfully with nitrogen in between the 4 pig train followed by gas. After pigging of NQO-C-24 section, gas from C-24 platform was used to propel the pigs in 22" pipeline segment. Finally, dewatering of both segments was carried out successfully and this is first time in ONGC, the operations carried out in a large scale
Polymer Injectivity Test in Mangala Field - A Significant Step towards Field Wide Implementation
Authors: Kumar M Suresh , Pandey Amitabh , Jha Manish Kumar
Published: March 2012

The Mangala Field is the largest discovered oil field in Barmer Basin, Rajasthan, India. The field contains medium gravity viscous crude (10-20 cp) in high permeability sands. The field is being developed under pattern and peripheral water injection. Due to the adverse mobility ratio, waterflooding is expected to result in lesser sweep and ultimately affect oil recovery. The potential for chemical enhanced oil recovery (EOR) has been recognized from an early stage in the field development, with polymer flooding identified for early implementation, followed by staged-wise implementation of Alkaline-Surfactant-Polymer (ASP) injection. To understand and evaluate the efficiency of chemical flooding, a closely spaced normal five spot EOR pilot is being conducted in the fluvial FM1 reservoir units of the Mangala Field.

Polymer injection in the pilot commenced in August 2011, with a series of short term polymer injectivity tests including multi rate test in one of the injectors. These tests provided useful insight about polymer rheological characteristics under reservoir conditions. Non-Newtonian behaviour of the polymer helped in injecting the ~30 cp solution within the designed surface pressure. Radial well modeling confirmed the shear thinning characteristics of the polymer which were in agreement with laboratory data, and that there has been no significant mechanical degradation of the polymer inside the well. Production logging conducted before, during and after the injectivity tests also show no significant change in injection profile as a result of the polymer injection. The injectivity test establishes that polymer injection is viable in Mangala reservoirs. The pilot results are important for an early implementation of fieldwide EOR in the Mangala Field.

This paper presents details of the polymer injectivity tests including bottom-hole pressure measurements and production logging conducted during the tests. Details of the single well fine scale modeling to match the injectivity test pressure behaviour are then described.
Geomechanical Evaluation of Mud Losses and Wellbore Instability in Mumbai High North Field – Implications to Infill Drilling and Reservoir Development
Authors: Kumar Rajesh , Perumalla Satya , Verma S. K.
Published: March 2012

Mumbai High North (MHN), an Indian Offshore oil field is a multilayered carbonate reservoir. This field has been producing for the last 35 years and there exists differential pressure depletion across the field. Mud losses while drilling the carbonate reservoirs in this field is a known serious problem and there is a direct impact on non productive time (NPT) and well cost adversely. Loss circulation during drilling appears to have become more severe with increased directional drilling activity and reservoir depletion in this field. There are also number of wellbore instability incidents like stuckpipe, tight hole and cavings evidenced at shale intervals especially when there was a drop in hydrostatic head of wellbore annulus due to mud losses in carbonate reservoirs.

At present, a comprehensive in-fill drilling campaign is under implementation with significant capital investment to enhance oil production from this field. This campaign covers mostly the Northern area of the field. A variety of drilling and completion problems have been encountered in the recent wells in this area which are attributed mainly due to mud losses while drilling.

In order to study the underlying mechanisms behind mud losses and wellbore instability, a geomechanical study was initiated using representative offset well data around one of planned in-fill drilling areas. The study includes constraining in-situ stresses, pore pressure and rock mechanical properties from available limited data set and reconciliation of results with relevant drilling experiences from offset wells.

This paper mainly discusses how the mud loss experience was analyzed and related with possible mechanisms with help of geomechanics. Based on this study, a risk matrix was generated to drill in-fill wells with appropriate mud weights and drilling practices. The study results also provided insights on possibilities of optimizing reservoir development strategy for future production.
Improvement of Vertical Conformance in Injectors - A Must for Fluvial Channel Reservoirs
Authors: Kothiyal Manish Dutt , Kumar Vikash , Kumar Pankaj , Parasher Arunabh , Singh Manjit Kumar , Murphy Robert
Published: March 2012

Mangala Field in Rajasthan, India was discovered in January 2004 and began production in August 2009. The main reservoir unit is Fatehgarh Formation, consisting of interbedded sands and shales. Upper Fatehgarh sand (FM-1) has almost 50 % of field STOIIP. It is a fluvial channel sand with excellent reservoir characteristics (average porosity ~ 25% and average permeability of more than 3000 md). Crude is waxy and wax dropout temperature is close to reservoir temperature. This reservoir is being developed by an inverted 9-spot hot waterflood, but a subsequent chemical flood EOR (polymer + ASP) is planned.

Currently, an inverted 5-spot pilot program is being carried out to assess the effectiveness of a chemical flood. Initial injection profiling data suggested that vertical conformance was poor, possibly due to poor injection water quality and wax dropout, but it was envisaged that selective chemical treatment of the channel sands would help in improving it. Initially, chemical assisted diversion techniques were applied in two wells which resulted in substantial reduction in ITHP with negligible improvement in conformance. Thereafter, a coiled tubing and straddle packer system was used to ensure correct placement of a series of chemicals targeting different damage mechanisms i.e. wax deposition and scaling issues.

Stimulation techniques included increasing the injection temperature of the water for wellbore heatup and wax dissolution, spotting and soaking of surfactants for dissolution of residual wax, followed by pin point injection of 15% HCL for dissolution of scales. Post stimulation injection logs showed an excellent achievement of conformance. An improved surface setup in the EOR pad (water heater, improved filter design) has helped in maintaining the injectivity over a longer time period. The lessons learned from this stimulation technique would prove to be critical for the FM1 sand, where improvement in vertical conformance would result in significantly higher recovery.
Pipeline Design and Maintenance with Special Reference to the High Paraffinic and High Pour Point Assam Crude Oil
Authors: BujarBaruah Prankush M
Published: March 2012

OIL INDIA LTD operates a number of oil and gas pipelines in the fields of Upper Assam. The total volume of oil handled annually is around 4 MMT. The crude oil produced is generally of waxy nature with a specific gravity of 0.87, having a high pour point of 25 deg.C and viscosity from 3.5cp till 6cp.

Over the period of years a number of methods have been developed with field and laboratory data to design, construct and maintain the pipelines including the flow lines from the well pads to the oil collection centers. At present an effective method to handle the highly paraffinic crude is the use of water bath type heaters with a heating range till 80 degree centigrade. Indirect heaters together or at times alone are used with pour point depressants, commercial name being Maxdip 1500 which is a vinyl acetate co-polymer.

During our design of new pipelines over and above to the codes of API 31.4/31.8 for pipeline design we have incorporated certain additions and deletions’ as per our requirement of handling the Assam oil. Certain redesign has also been done in certain pipelines to handle very high paraffinic crude. The 8" Duliajan Digboi refinery crude oil delivery line is an example. Design modifications were done on the existing pipeline without effecting the refinery operations. For the Salmari field heavy oil, in-house design and maintenance efforts with combination of Merus rings and heating through bath type indirect heaters has enabled a trouble free operation. To overcome the problem of congealing in well flow lines a number of methods like steam injection, heating of the crude oil and gas and use of high pressure hot oil pumps have been developed to redesign, re-modify the existing flow lines. Recently we had undertaken a pilot project to introduce a scrapper tool inside the closed circuit loop of the well flow line.

With the above endeavors developed in-house we have been able to maintain modify design and construct (lay) pipelines in our operational area with almost 100% flow assurance
PVC mixtures’ mechanical properties with the addition of modified calcite as filler
Authors: Mihajlovic Slavica , Sekulic Zivko , Vucinic Dusica , Jovanovic Vladimir , Kolonja Bozo
Published: March 2012

In this study mechanical properties of PVC mixtures (PVC, stabilizer,
lubricant, filler) such as tensile strength, tensile elongation, breaking
strength, and breaking elongation were investigated. Unmodified calcite, as
well as calcite modified by stearic acid, were used as fillers in wet and dry
processes. The PVC mixtures containing the calcite modified by wet procedure
have better mechanical properties compared to those with the calcite modified
by the dry process. Tensile and breaking strength of the PVC mixture
containing the calcite modified with 1.5% stearic acid using wet process, are
higher for 2.8% and 5.2%, respectively, compared to the PVC mixture
containing the calcite modified with the same amount of acid used in the dry
process. The tensile strength difference between the mixtures increases with
the increase of the concentration of used stearic acid up to 3%. The strength
of PVC mixture with the calcite modified by wet process is 3.1% higher
compared to the mixture containing calcite modified by dry process. The
results showed that the bonding strength between calcite and the adsorbed
organic component affected tensile strength, tensile elongation and breaking
strength of the PVC mixtures. The best filler was obtained by wet
modification using 1.5% stearic acid solution that provided the formation of
a stearate monolayer chemisorbed on calcite. The PVC mixtures containing the
calcite modified by wet process using 1.5% stearic acid solution exhibited
the best mechanical properties. This calcite was completely hydrophobic with
dominant chemically adsorbed surfactant, which means that stearate
chemisorbed on calcite provided stronger interaction in the calcite-stearic
acid-PVC system.
Influence of acid rain components on radiocesium-137 desorption from Cetraria islandica (L.) Ach. lichen
Authors: Cuculovic Ana , Veselinovic Dragan , Miljanic Scepan
Published: March 2012

Desorption of 137Cs from Cetraria islandica (L.) Ach. lichen was performed by
five consecutive desorptions with five identical solution volumes. Solutions
of H2SO4, HNO3 and their mixtures, with pH 4.61, 5.15 and 5.75 were used for
desorption. The desorbed amount of 137Cs (average value, all solutions used)
from lichen, for a given pH value was 49.2% for pH 4.61; 47.0% for pH 5.15
and 47.6% for pH 5.75. The obtained values of the desorbed amount of 137Cs
from lichen are in accordance with the data obtained in earlier work, when
46.2 % 137Cs was desorbed from lichen for pH 3.75, and 47.2% was desorbed for
pH 2.87. A higher percentage of 59.8%, obtained for pH 2.00 indicates
increased activity of H+ ions. The amount of desorbed 137Cs from lichen using
solutions corresponding to acid rain cannot be lower than the stated values
as they contain other substances besides the acid solutions used in this
work.
Surface plasmon resonance of Ag organosols: Experimental and theoretical investigations
Authors: Vukoje Ivana , Bozanic Dusan , Dzunuzovic Jasna , Bogdanovic Una , Vodnik Vesna
Published: March 2012

The aim of this paper is to investigate and compare the changes in surface
plasmon resonance (SPR) of silver (Ag) hydrosol and organosols obtained by
experimental and theoretical approaches. Silver nanoparticles (Ag NPs) of 5 ?
1.5 nm in diameter were prepared in water by reduction of silver nitrate with
sodium borohydride. Nanoparticles were subsequently transferred into
different organic solvents (chloroform, hexane, toluene, 1,2-dichlorobenzene)
using oleylamine as a transfer agent. These solvents were chosen because of
the differences in their refractive indices. Using UV-Vis absorption
spectrophotometry and transmission electron microscopy (TEM), we confirmed
that there were no shape and size changes of the nanoparticles upon the
transfer to the organic phase. The absorption spectra of the obtained Ag
organosols showed only changes in the position of SPR band depending on
dielectric property of the used solvent. To analyze these changes, absorption
spectra were modelled using Mie theory for small spherical particles. The
experimental and theoretical resonance values were compared with those
predicted by Drude model and its limitations in the analysis of absorption
behavior of Ag NPs in organic solvents were briefly discussed.
Co(salen) catalysed oxidation of synthetic lignin-like polymer: Co(salen) effects
Authors: Zhou Xue-Fei , Liu Jing
Published: March 2012

In this paper, Co(salen) [salen = N, N?-bis(salicylidene)ethylenediamine]
complex was studied as oxygen activators for the catalytic oxidation of a
lignin model polymer using water as the solvent, with molecular oxygen and
hydrogen peroxide as the oxidants. The effect of Co(salen) on oxidation was
tested by spectroscopic methods (FTIR, 13C-NMR and GC-MS). The reactions
catalysed by Co(salen) included C?-alcohol oxidation, C?-C? side chain
cleavage, demethoxylation, aromatic ring cleavage, and ?-O-4 cleavage. In
addition to the mechanistic information obtained, the effect of Co(salen)
suggests that Co(salen) can be important for the catalytic oxidation, as they
affect the oxidation of lignin model polymer. The reaction performed in the
presence of Co(salen) was more efficient than without it. The formation of
aldehyde in the catalytic oxidation, as shown by GC-MS, could be identified
as the mechanism of oxidative cleavage of the ?-O-4 bonds.
The stress tensor of an atomistic system
Authors: Morante Silvia , Rossi Giancarlo , Testa Massimo
Published: March 2012

We prove that the stress tensor conservation equation expressing the local equilibrium condition of a body results from the invariance of its partition function under canonical point transformations. From this result the expression of the stress tensor of a general atomistic system (with short range interactions) in terms of its microscopic degrees of freedom can be obtained. The derivation, which can be extended to encompass the quantum mechanical case, works in the canonical as well as the micro-canonical ensemble and is valid for systems endowed with arbitrary boundary conditions. As an interesting by-product of our general approach, we are able to positively answer the old question concerning the uniqueness of the stress tensor expression.
Microstructure and Properties of Plasma Sprayed Lead Zirconate Titanate (PZT) Ceramics
Authors: Ctibor Pavel , Pala Zdenek , Boldyryeva Hanna , Sedláček Josef , Kmetík Viliam
Published: March 2012

Lead zirconate titanate (PZT) was plasma sprayed onto various substrates of different character. Additionally, a free-standing body made by plasma spraying was investigated. X-ray diffraction analyses of a decomposition of the as-sprayed coating products detected components of the PT-PZ system as well as binary oxides—PbO and ZrO2. Due to the comparatively complex phase character, the Curie temperature monitored by DTA, had a smeared appearance without pronounced maxima. The corresponding electrical properties are comparable with those typically observed for CaTiO3, but are worse than the normal values of bulk PZT due to defective stoichiometry.
Association of Finite-Time Thermodynamics and a Bond-Graph Approach for Modeling an Endoreversible Heat Engine
Authors: Dong Yuxiang , El-Bakkali Amin , Descombes Georges , Feidt Michel , Périlhon Christelle
Published: March 2012

In recent decades, the approach known as Finite-Time Thermodynamics has provided a fruitful theoretical framework for the optimization of heat engines operating between a heat source (at temperature ) and a heat sink (at temperature ). The aim of this paper is to propose a more complete approach based on the association of Finite-Time Thermodynamics and the Bond-Graph approach for modeling endoreversible heat engines. This approach makes it possible for example to find in a simple way the characteristics of the optimal operating point at which the maximum mechanical power of the endoreversible heat engine is obtained with entropy flow rate as control variable. Furthermore it provides the analytical expressions of the optimal operating point of an irreversible heat engine where the energy conversion is accompanied by irreversibilities related to internal heat transfer and heat dissipation phenomena. This original approach, applied to an analysis of the performance of a thermoelectric generator, will be the object of a future publication.
Suicide Methods in Asia: Implications in Suicide Prevention
Authors: Wu Kevin Chien-Chang , Chen Ying-Yeh , Yip Paul S. F.
Published: March 2012

As the largest continent in the World, Asia accounts for about 60% of World suicides. Preventing suicide by restricting access to suicide methods is one of the few evidence-based suicide prevention strategies. However, there has been a lack of systematic exploration of suicide methods in Asian countries. To amend this shortage, the current review examines the leading suicide methods in different Asian countries, their trend, their age- and sex- specific characteristics, and their implications for suicide prevention. In total, 42 articles with leading suicide methods data in 17 Asian countries/regions were retrieved. The epidemiologic characteristics and recent trends of common suicide methods reflect specific socio-cultural, economic, and religious situations in the region. Common suicide methods shift with the introduction of technologies and constructions, and have specific age- or sex-characteristics that may render the restriction of suicide methods not equally effective for all sex and age sub-groups. Charcoal burning, pesticide poisoning, native plant poisoning, self-immolation, and jumping are all prominent examples. In the information society, suicide prevention that focuses on suicide methods must monitor and control the innovation and spread of knowledge and practices of suicide “technologies”. It may be more cost-effective to design safety into technologies as a way of suicide prevention while there is no rash of suicides yet by the new technologies. Further research on suicide methods is important for public health approaches to suicide prevention with sensitivity to socio-cultural, economic, and religious factors in different countries.
Aminodi(hetero)arylamines in the Thieno[3,2-b]pyridine Series: Synthesis, Effects in Human Tumor Cells Growth, Cell Cycle Analysis, Apoptosis and Evaluation of Toxicity Using Non-Tumor Cells
Authors: Calhelha Ricardo C. , Ferreira Isabel C. F. R. , Peixoto Daniela , Abreu Rui M. V. , Vale-Silva Luís A. , Pinto Eugénia , Lima Raquel T. , Alvelos M. Inês , Vasconcelos M. Helena , Queiroz Maria-João R. P.
Published: March 2012

Three aminodi(hetero)arylamines were prepared via a palladium-catalyzed C-N Buchwald-Hartwig coupling of methyl 3-aminothieno[3,2-b]pyridine-2-carboxylate with different bromonitrobenzenes, followed by reduction of the nitro groups of the coupling products to the corresponding amino compounds. The aminodi(hetero)arylamines thus obtained were evaluated for their growth inhibitory effect on four human tumor cell lines MCF-7 (breast adenocarcinoma), A375-C5 (melanoma), NCI-H460 (non-small cell lung cancer) and HepG2 (hepatocellular carcinoma). The toxicity to non-tumor cells was also evaluated using a porcine liver primary cell culture (PLP1), established by us. The aminodi(hetero)arylamine with the NH2 group in the ortho position and an OMe group in the para position to the NH of the di(hetero)arylamine, is the most promising compound giving the lowest GI50 values (1.30–1.63 µM) in all the tested human tumor cell lines, presenting no toxicity to PLP1 at those concentrations. The effect of this compound on the cell cycle and induction of apoptosis was analyzed in the NCI-H460 cell line. It was observed that it altered the cell cycle profile causing a decrease in the percentage of cells in the G0/G1 phase and an increase of the apoptosis levels.
A High Sensitivity Three-Dimensional-Shape Sensing Patch Prepared by Lithography and Inkjet Printing
Authors: Huang Yi-Ren , Kuo Sheng-An , Stach Michal , Liu Chia-Hsing , Liao Kuan-Hsun , Lo Cheng-Yao
Published: March 2012

A process combining conventional photolithography and a novel inkjet printing method for the manufacture of high sensitivity three-dimensional-shape (3DS) sensing patches was proposed and demonstrated. The supporting curvature ranges from 1.41 to 6.24 ´ 10−2 mm−1 and the sensing patch has a thickness of less than 130 μm and 20 ´ 20 mm2 dimensions. A complete finite element method (FEM) model with simulation results was calculated and performed based on the buckling of columns and the deflection equation. The results show high compatibility of the drop-on-demand (DOD) inkjet printing with photolithography and the interferometer design also supports bi-directional detection of deformation. The 3DS sensing patch can be operated remotely without any power consumption. It provides a novel and alternative option compared with other optical curvature sensors.
Reducing False Negative Reads in RFID Data Streams Using an Adaptive Sliding-Window Approach
Authors: Massawe Libe Valentine , Kinyua Johnson D. M. , Vermaak Herman
Published: March 2012

Unreliability of the data streams generated by RFID readers is among the primary factors which limit the widespread adoption of the RFID technology. RFID data cleaning is, therefore, an essential task in the RFID middleware systems in order to reduce reading errors, and to allow these data streams to be used to make a correct interpretation and analysis of the physical world they are representing. In this paper we propose an adaptive sliding-window based approach called WSTD which is capable of efficiently coping with both environmental variation and tag dynamics. Our experimental results demonstrate the efficacy of the proposed approach.
Measuring hoof slip of the leading limb on jump landing over two different equine arena surfaces
Authors: Orlande O. , Hobbs S.J. , Martin J.H. , Owen A.G. , Northrop A.J.
Published: March 2012

The amount of hoof slip at the moment of impact can cause musculoskeletal injuries to the horse. Risk of injury is influenced by surface properties, however there is limited understanding of the effect on hoof slip during jump landing. The objectives of this study were to compare hoof slip on two different surfaces and investigate relationships between hoof slip and surface properties. A contact mat and hoof reference marker were designed and validated, the former to indicate the moment of impact and the latter to provide a visible reference marker on the lateral hoof wall. The leading right forelimb of six horses was recorded during jump landing on two different surfaces. Five trials, plus one where the forelimb landed on a contact mat were recorded at 500 Hz using a calibrated high speed camera positioned perpendicular to landing. Surface hardness, penetrability and traction were measured between horses. Horizontal displacement of the hoof reference marker was plotted and smoothed with a Butterworth filter at 25 Hz cut-off. Hoof slip was measured from impact to mid-stance. Data were analysed using ANOVA and Pearson correlations. A significant difference in hoof slip (10% wax = 4.9�2.1 cm and 3% wax = 7.4±3.6 cm) was found between the two surfaces (P<0.01). In addition, hoof slip was correlated with all surface measurements (hardness, penetrability and traction) on the 10% wax surface, but none on the 3% wax surface. Wax content appears to influence hoof slip during jump landing as greater hoof slip was measured on a 3% wax surface and variability on this surface was greater for the group. The results suggest that wax content had an effect on surface properties and greater variability in hardness and traction on the 3% wax surface influenced the consistency with which the horses jumped upon it.