bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of Skin Factor and Pseudo-steady State Horizontal Wells Productivity for Various Drainage Areas
Authors: Bahadori A.
Published: June 2012

In the present work, an attempt has been made to develop a simple-to-use method to estimate shape-related skin factor for horizontal wells centrally located within square and rectangular drainage areas. The results can be used in follow-up calculations for rapid estimating the pseudo-steady state horizontal wells productivity. Estimations are found to be in excellent agreement with the reliable data in the literature with average absolute deviation being less than 1%. The tool developed in this study can be of immense practical value for petroleum engineers to have a quick check of shape-related skin factors, for horizontal wells at various conditions without opting for any field trials. In particular, reservoir and production engineers would find the approach to be user-friendly with transparent calculations involving no complex expressions.
Performance Analysis in Coal Seam Gas
Authors: Gaurav Kumar , Husen Anwar , Saada Tamer , Kumar Sunil
Published: June 2012

Exploration and Production companies operating in Coal Seam Gas (CSG) consistently face challenges in regards to efficient well monitoring and operations. CSG wells are completed with artificial lift and have fluid flow in both tubing and annulus. The water is being produced with the help of artificial lift through tubing and gas is produced through annulus. Well production depends on artificial lift performance and flow profile within the tubing and fluid level in annulus. The well modelling technique requires a common nodal solution from tubing and annulus which requires an iterative procedure to suggest optimum operating parameters and predicts rates for various scenarios.

CSG wells have low gas rates which induce slugging in the annulus and hence adversely affect the well performance. The unwanted down hole pressure variation leads to reduction in lift efficiency both in tubing and annulus. The operating condition of artificial lift requires optimisation to operate the well at maximum production potential. The fluctuation in liquid rates from wells needs to be minimised for process stabilisation and hence reduction in back pressure effects on other wells in surface network.

The main objective of the exercise presented in this paper is to model the flow path inside tubing and annulus for an artificially lifted CSG well. There is currently a gap in the industry on how such wells should be modelled since the water & gas are separated down hole and they follow different flow paths. A flowing well has a common down hole pressure at different surface flowing tubing head pressure and flowing casing pressure. This project involves development of a software tool on the basis of industry research which can execute performance analysis in CSG wells. In addition, the scope of the project includes identifying basic guidelines for operating a CSG well.

To achieve this objective all issues related with CSG well operation were collectively analysed and scope of work was drawn. The requirement of performance analysis tool for unconventional wells was acknowledged and the workflow for optimum well operation was proposed with available software applications. An Excel based application running on visual basic code was created which can communicate with a multiphase pressure calculator and perform system analysis for CSG wells. The proposed tool was developed and validated on real field data from BG Group.

This paper covers the operating issues, proposed workflow for performance analysis for CSG wells, development stages of the tool, its application on real field data, validation with field measurements and limitation associated with developed workflow. This thesis also covers the main aspects considered to monitor performance of CSG wells; the effect of surface and downhole parameters on well performance and how these concepts and diagnosis can help to achieve production targets in CSG field.
"Volumetric" Reservoir Waters Out: Enhanced Aquifer Characterization Using PTA Derived Boundary Tracking
Authors: Khan Z. , Roopa I. , Baksh K. , Partap R , Mohammed S
Published: June 2012

The Mahogany field was discovered in 1968 and appraisal was completed in 1996. The field is located 50 miles offshore eastern Trinidad (Fig. 1) with the platforms situated in water depths of 230 feet and contains more than 30 stacked sands (17 of which are gas bearing) with a development footprint area of c. 10000 acres. Initially the field’s resources were booked assuming volumetric depletion was the dominant drive mechanism (Nandalal and Gunter 2003), however the updated understanding showed that water drive was the prevailing mechanism with near volumetric depletion being exhibited by only two reservoirs within the field, the TQ51 FB4 and TQ51 FB5.

There were two development wells in the TQ51 FB4, MA04 and MB13. MA04 became liquid loaded and stopped producing in March 2004 after fourteen months of concurrent production with MB13. MA04 showed volumetric behaviour until late life. Due to the volumetric response exhibited by the reservoir, the MB13 well was assigned low pressure access resources and was also used as a swing well to compensate for gas market demand fluctuations.

Conventional material balance techniques (P/Z, Havlena Odeh, van Everdingen Hurst aquifer match) led to the belief that the drive mechanism was volumetric to very weak aquifer support. Pressure Transient Analysis (PTA) and pore volume material balance estimates showed the presence of an edge drive aquifer. This was corroborated by geological studies which showed that although the two reservoirs had the same initial gas water contact (GWC), with production they became two separate compartments exhibiting different properties, the aquifer acting via an edge drive mechanism.
Artificial-Lift Operation Technologies of Low-Pressure Flooded Gas and Gas-Condensate Wells
Authors: Drozdov A. N. , Bulatov G. G. , Lapoukhov A. N. , Mamedov E. A. , Malyavko E. A. , Alekseev Y. L.
Published: June 2012

One of the main reasons, leading to the production decline of gas and gas-condensate wells is the accumulation of liquid fluid on the bottom of the well and formation of liquid blockage. Under certain conditions, bottom hole pressure drops, flow rate declines and gas velocity reduction becomes insufficient for the liquid lifting. Periodic gas purging of low-pressure wells practiced in Russia for water extraction, leads to the unproductive losses of hydrocarbons and forbids achieving stable operation. It leads to the retirement of wells out of the producing well stock, formation of dead zones with entrapped gas and, as the final result, to the waterflood hydrocarbon recovery drawdown. This problem can be solved by putting low-pressure flooded wells on pump, as international experience being indicative of its benefits.

Various engineering solutions based on the field tests of the techniques, mentioned above, were examined. The most suitable and viable technologies, for one of the Russian fields to be at the latest stage of reservoir development, were electric submersible centrifugal pumps (ESP) and electric progressive cavity pumps (ESPCP): with the removing of water to the surface and the subsequent injection of water into injection wells, and also with the injection of water into the underlying aquifer in the existing producing well.

We developed a rational method of hydraulic calculation and selection ESP and ESPCP for different operating conditions. Preliminary bench experiments of ESP’s, centrifugal gas separators and separator of mechanical impurities were carried out. The equipment has proven its efficiency.

The proposed solution will ensure the efficient functioning of the system of artificial-lift gas and gas-condensate well operation without using the unique expensive equipment. Also in a short period of time it could allow adapting the quantity produced submersible pumps for the conditions of gas industry.
Memory-Based Depth Control Technique -- Practical Application for Precise Deployment of Explosives on Slickline, Coiled Tubing And Drillpipe
Authors: Friedli J. , Charles N.
Published: June 2012

With the advent of intelligent memory based controllers for initiation of pyrotechnic passenger loads, there has been an expansion of the range of services available to operators via non-traditional conveyance. The primary concerns for non-real time initiation of pyrotechnics are safety and depth control. Modern memory based trigger devices include multiple fail safe routines within the fire command sequence and these are well documented in technical and commercial literature. This paper deals with the concepts and challenges of achieving reliable depth control.

The technique employed here applies to all non-conductive deployment systems, (slickline, conventional coiled tubing, and jointed pipe) and does not require specialized surface equipment other than standard depth encoders and memory correlation logging tools (typically Gamma Ray and or CCL). The technique relies on understanding the limitations and observing a few simple conventions. A reasonable analogy of the technique would be aviation under IFR (Instrument Flight Rules) versus VFR (Visual Flight Rules). Both methods are valid when the accepted methodology is respected.

This is an important development in the industry because it affords flexibility to operators where there are fiscal or logistical barriers to conventional, real time correlation. Some benefits:Reduce critical path rig operations by multi-tasking standard completion stepsMinimize rig up / rig down time by concentrating more tasks into a single deployment mediumPermit access to previously unrecoverable shut in reserves. Many platforms will accept no more than a small slickline unit. Wells that previously would require prohibitively expensive rig intervention can be re-completed using slickline.Taking advantage of these options, offshore facility designers can realize significant savings in fabrication.

The paper demonstrates that, when proper conventions are observed, the technique reliably deploys payloads with precision compatible to the full range of pyrotechnic completion and intervention services in the modern energy services market.
Re-Innovating Old Technology Improves Efficiency of Proven Coiled-Tubing Stimulation
Authors: Lindsay S. , Ables C. , Holden D.
Published: June 2012

Worldwide demand for energy has forced the energy services industry to increase process efficiency and create innovative new methods of fracture stimulation optimization. Pinpoint fracturing methods represent a divergence from conventional fracture stimulation methods, which provide minimal optimization to reservoir volume. Pinpoint fracturing methods allow multiple interval completions to be performed efficiently, helping ensure that all intervals receive the optimum fracture intensity.

To increase process efficiency, coiled tubing (CT) is used to hydra-jet perforate intervals for individual fracturing treatments at predetermined depths. The process uses a unique bottomhole assembly (BHA), which was recently redesigned to increase the efficiency of the hydra-jetting tool and isolate the fracture stimulation from previous intervals. This pinpoint fracturing method does not require removing the CT from the well between treatments. Risks of non-productive time (NPT) are mitigated because contingencies for early screenout avoidance can be initiated immediately during the fracture stimulation with minimal impact on overall completion costs. Treating intervals individually substantially helps reduce the amount of hydraulic horsepower required onsite, further reducing completion costs and the risk of NPT caused by down horsepower.

Re-innovating fracture stimulation technology is often a challenge. The new technology must add value and efficiency to the process, while remaining reliable and commercially viable. In this case, these requirements were met by reducing the complexity of the BHA while increasing hydra-jetting efficiency. The elimination of moving parts increased the process reliability and simplified operational procedures.

This paper examines the re-innovation of this older technology.
Unraveling the Performance Characteristics of the Most Mature Shallow Gas Reservoir in the Trinidad Acreage in the Columbus Basin
Authors: Roopa I. , Benjamin K.
Published: June 2012

The BP Trinidad gas fields are located in the Columbus basin, 35-40 miles off the southeast coast of Trinidad in water depths of between 200 to 300 feet. The fields are comprised of highly faulted stacked sandstone reservoir units of varying ages between Quaternary to Pleistocene. Most reservoir units contain original gas in place of less than 0.5 tcf and are usually produced by one or two wells. The shallow gas reservoirs (< 4500 ft TVDSS) constitute a significant percentage of the non-producing BP Trinidad gas portfolio. Reservoir data, such as rock compressibility, and performance data such as recovery factors are lacking in both the local and global database for analogous reservoirs at these depths.

Initially these shallow gas reservoirs were considered as drilling hazards for deeper reservoirs therefore well paths and platform locations avoided them as recovery from them were initially expected to be very poor. The shallowest producing reservoir unit to date is from the TP95 reservoir in the Greater Cassia Field Complex and it has one producer. This reservoir depth is 4200ft TVDSS and it has been on production since 2003, exceeding expectations with its recovery. This paper investigates the key uncertainties associated with this reservoir including depth conversion (since it is overlain by other shallow gas reservoirs), rock compressibility and aquifer support. It also shows the well and reservoir performance data, key surveillance data collected as well as types of analysis and modeling performed to help understand and predict the reservoir performance given the aforementioned subsurface uncertainties.
Effect of Gas Cap and Aquifer Strength on Optimal Well Location for Thin-Oil Rim Reservoirs
Authors: Iyare U. C. , Marcelle-De Silva J.
Published: June 2012

Many hydrocarbon reservoirs have an oil bearing zone, sandwiched between gas and water bearing zones. For these reservoirs, considerable studies are conducted to optimize the location of wells in the oil rim so as to maximize oil recovery. Few studies however have investigated the conditions under which wells could be located in either the gas cap or the water leg so as to also maximize oil recovery.

This study investigates the effect of gas cap and aquifer sizes on oil recovery from a reservoir with a thin oil rim using a single well numerical reservoir simulator model. Sensitivity studies were conducted by varying gas cap size, aquifer size and well location, and analyzing their effect on oil recovery.

The results indicated that for a reservoir with a large gas cap, it may be more favorable to place the horizontal well below the water-oil contact; for a reservoir with a small gas cap and large aquifer, it may be advantageous to place the horizontal well above the gas-oil contact.

This study is significant since thin oil rims are especially prominent in the prolific gas province offshore the east coast of Trinidad, and maximizing oil recovery, the more valuable resource, has positive financial implications.
Elimination of arsenic (III) by adsorption on coal resulting from date pits and activated thermally and chemically
Authors: Ziati Mounir , Hazourli Sabir , Nouacer Sana , Khelaifia Fatma Zohra
Published: June 2012

The objective of this study is the valorisation of a lignocellulosic natural residue, date pits, and its application in the removal by adsorption of the arsenic (III) contained in water. The chronological stages in obtaining coal were: cleaning, drying, crushing and finally either a thermal treatment by pyrolysis at 900 °C (CAP1) or a chemical pretreatment with iron oxide of the natural residue followed by carbonisation at 600 °C (CAP2). The choice of iron oxide is based on the fact that arsenic (III) has strong affinities for the hydroxide and oxide of this metal. The characterisation of the carbonaceous matter showed properties comparable with those of many industrially produced coals. Retention tests of arsenic (III) on the two adsorption materials studied gave a maximum capacity of adsorption (at 20 °C and 24 h of contact time) of about 25 mg/g for the chemically activated carbon and 21 mg/g for the thermally activated one. The study of the influence of pH and temperature showed that at neutral pH and ambient temperature (T = 20 °C), the optimal adsorption of arsenic (III) follows quite closely the Langmuir and Freundlich models. The kinetics of adsorption is slow and is of pseudo-second order type.
A knowledge management methodology for the integrated assessment of WWTP configurations during conceptual design
Authors: Garrido-Baserba M. , Reif R. , Rodriguez-Roda I. , Poch M.
Published: June 2012

The current complexity involved in wastewater management projects is arising as the XXI century sets new challenges leading towards a more integrated plant design. In this context, the growing number of innovative technologies, stricter legislation and the development of new methodological approaches make it difficult to design appropriate flow schemes for new wastewater projects. Thus, new tools are needed for the wastewater treatment plant (WWTP) conceptual design using integrated assessment methods in order to include different types of objectives at the same time i.e. environmental, economical, technical, and legal. Previous experiences used the decision support system (DSS) methodology to handle the specific issues related to wastewater management, for example, the design of treatment facilities for small communities. However, tools developed for addressing the whole treatment process independently of the plant size, capable of integrating knowledge from many different areas, including both conventional and innovative technologies are not available. Therefore, the aim of this paper is to present and describe an innovative knowledge-based methodology that handles the conceptual design of WWTP process flow-diagrams (PFDs), satisfying a vast number of different criteria. This global approach is based on a hierarchy of decisions that uses the information contained in knowledge bases (KBs) with the aim of automating the generation of suitable WWTP configurations for a specific scenario. Expert interviews, legislation, specialized literature and engineering experience have been integrated within the different KBs, which indeed constitute one of the main highlights of this work. Therefore, the methodology is presented as a valuable tool which provides customized PFD for each specific case, taking into account process unit interactions and the user specified requirements and objectives.
A comparison of different activated carbon performances on catalytic ozonation of a model azo reactive dye
Authors: Gül Ş. , Eren O. , Kır Ş. , Önal Y.
Published: June 2012

The objective of this study is to compare the performances of catalytic ozonation processes of two activated carbons prepared from olive stone (ACOS) and apricot stone (ACAS) with commercial ones (granular activated carbon-GAC and powder activated carbon-PAC) in degradation of reactive azo dye (Reactive Red 195). The optimum conditions (solution pH and amount of catalyst) were investigated by using absorbencies at 532, 220 and 280 nm wavelengths. Pore properties of the activated carbon (AC) such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by N2 adsorption. The highest BET surface area carbon (1,275 m2/g) was obtained from ACOS with a particle size of 2.29 nm. After 2 min of catalytic ozonation, decolorization performances of ACOS and ACAS (90.4 and 91.3%, respectively) were better than that of GAC and PAC (84.6 and 81.2%, respectively). Experimental results showed that production of porous ACs with high surface area from olive and apricot stones is feasible in Turkey.
Improving design factors of air diffuser systems based on field conditions of dam reservoirs: CFD simulation approach
Authors: Shin Sangmin , Lee Seungjae , Lee Sangeun , Yum Kyungtaek , Park Heekyung
Published: June 2012

This study aims to improve the design factors of air diffuser systems that have been analyzed in laboratory experiments, with consideration of the field conditions of dam reservoirs. In this study, the destratification number (DN), destratification radius, and efficiency are considered as design factors. The computational fluid dynamics (CFD) simulation experiment is performed in diverse field conditions in order to analyze these factors. The results illustrate the wider range of DN values in field conditions and the relationship of the destratification radius and efficiency to DN. The results can lead to better performance of air diffuser systems and water quality management in dam reservoir sites.
Evaluation of water security: an integrated approach applied in Wuhan urban agglomeration, China
Authors: Shao Dongguo , Yang Fengshun , Xiao Chun , Tan Xuezhi
Published: June 2012

To evaluate water security, the Water Resources Sustainability Evaluation Model has been developed. The model employs four criteria (economic development, flood control security, water supply security, and water environment security) and has 22 indicators, integrating them using their relative weights. The model is applied to evaluate the water security of Wuhan urban agglomeration, China. The values of the indicators are normalized using the exponential efficacy functions based on the law of diminishing marginal utility. The evaluation results show that, overall, the state of water security in Wuhan urban agglomeration is good, which is in good agreement with the true situation. The comparison between the results of the model and other three evaluation methods by the Spearman coefficient of rank correlation verifies the science and reliability of the developed model. Consequently, it is concluded that the model can be an effective tool for evaluating the states of water security and provide a basis on which to create policies for improving inadequacies in water security.
Influence of groundwater composition on subsurface iron and arsenic removal
Authors: Moed D. H. , van Halem D. , Verberk J. Q. J. C. , Amy G. L. , van Dijk J. C.
Published: June 2012

Subsurface arsenic and iron removal (SAR/SIR) is a novel technology to remove arsenic, iron and other groundwater components by using the subsoil. This research project investigated the influence of the groundwater composition on subsurface treatment. In anoxic sand column experiments, with synthetic groundwater and virgin sand, it was found that several dissolved substances in groundwater compete for adsorption sites with arsenic and iron. The presence of 0.01 mmol L−1 phosphate, 0.2 mmol L−1 silicate, and 1 mmol L−1 nitrate greatly reduced the efficiency of SAR, illustrating the vulnerability of this technology in diverse geochemical settings. SIR was not as sensitive to other inorganic groundwater compounds, though iron retardation was limited by 1.2 mmol L−1 calcium and 0.06 mmol L−1 manganese.
Monitoring the performance of a storm water separating manifold with distributed temperature sensing
Authors: Langeveld J. G. , de Haan C. , Klootwijk M. , Schilperoort R. P. S.
Published: June 2012

Storm water separating manifolds in house connections have been introduced as a cost effective solution to disconnect impervious areas from combined sewers. Such manifolds have been applied by the municipality of Breda, the Netherlands. In order to investigate the performance of the manifolds, a monitoring technique (distributed temperature sensing or DTS) using fiber optic cables has been applied in the sewer system of Breda. This paper describes the application of DTS as a research tool in sewer systems. DTS proves to be a powerful tool to monitor the performance of (parts of) a sewer system in time and space. The research project showed that DTS is capable of monitoring the performance of house connections and identifying locations of inflow of both sewage and storm runoff. The research results show that the performance of storm water separating manifolds varies over time, thus making them unreliable.
Influence of physico-chemical treatment on the subsequent biological process treating paper industry wastewater
Authors: el khames Saad Mouhamed , Moussaoui Younes , Zaghbani Asma , Mosrati Imen , Elaloui Elimame , Ben Salem Ridha
Published: June 2012

The present paper presents the main results of the biodegradation study of paper industry wastewater through physico-chemical treatment. Indeed, around 60% of chemical oxygen demand (COD) removal can be achieved by electroflocculation treatment. Furthermore, a removal efficiency of the COD of almost 91% has been obtained by biological treatment, with activated amount of sludge for 24 h of culture. Concerning the physico-chemical pre-treatment of the untreated, filtered and electroflocculated rejection effluents, it has been investigated through the degradation curve of COD studies.
Characterization of runoff from various urban catchments at different spatial scales in Beijing, China
Authors: Zhang W. , Che W. , Liu D. K. , Gan Y. P. , Lv F. F.
Published: June 2012

In order to investigate the characterization of runoff in storm sewer from various urban catchments, three monitoring systems at different spatial scales have been installed separately. They have been held since July 2010 in urban area of Beijing (China). The monitoring data revealed that chemical oxygen demand (COD), total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP), and NH3-N values significantly exceed the Class V surface water quality standard developed by Ministry of Environmental Protection of the People's Republic of China (MEP). A surface solids buildup and wash off model for small watershed was adopted to analyze and discuss the process of a runoff pollutant discharge. More than a half of pollutant parameters presented a good fit to the model. However, a slightly worse-fit to the wash off model appeared in less than half of the data. Due to the influence of sewer sediments, sewer system characteristics, catchment characteristics, and other reasons, first flush was seldom observed in storm sewer runoff from these three survey areas. Meanwhile, the correlation between TSS and any other pollutant was analyzed according to cumulative load of pollutants in runoff events. An event mean concentrations (EMCs) approach was adopted to quantify the pollution of runoff. EMCs of various pollutants in storm sewer runoff between different rainfall events were slightly higher than the typical values observed in similar areas at home and abroad, according to other studies reported in literature. Based on quantitative analysis, it can be concluded that urban non-point source pollution is recognized as the major causes of quality deterioration in the receiving water bodies. This is after the point source pollution has been controlled substantially in Beijing. An integrated strategy, which combines centralized and decentralized control, along with the conditions of meteorology, hydrology, urban planning, existing drainage system, etc., will be an effective and economic approach to urban runoff pollution control.
Performance of a non-phosphorus antiscalant on inhibition of calcium-sulfate precipitation
Authors: Xue Xiaoxu , Fu Change , Li Na , Zheng Fangfang , Yang Weiben , Yang Xiaodi
Published: June 2012

The aim of this study is to report on the performance of a novel non-phosphorus antiscalant, acrylic acid (AA)-allylpolyethoxy carboxylate (APEC), being developed for calcium-sulfate scale inhibition in industrial water systems. The performance of AA-APEC on calcium-sulfate scale inhibition was compared with that of the two commercial inhibitors, polyamino polyether methylene phosphonates (PAPEMP) and polyacrylic acid (PAA), containing the same polyethylene glycol segments or carboxyl functional groups as AA-APEC. The study indicated that AA-APEC could act as a highly effective calcium sulfate inhibitor, having strong ability to inhibit the precipitation of calcium sulfate at a dosage of 2 mg L−1, showing approximately 83.6% inhibition. The results also showed that AA-APEC dosage, the solution pH, inhibiting temperature, concentration of Ca2+, and SO42− all play important roles in inhibiting calcium-sulfate precipitation. The precipitation thermodynamics and kinetics at different temperatures were also discussed. X-ray diffractometer (XRD) and scanning electron microscope (SEM) analysis showed that AA-APEC strongly affected the texture and the morphology of the deposited calcium sulfate. Calcium sulfate has been inhibited through stabilization by adsorption onto crystal growth sites of nascent crystals altering their morphology.
Spatial and seasonal distribution of synthetic musks in sewage treatment plants of Shanghai, China
Authors: Sang Wenjing , Zhang Yalei , Zhou Xuefei , Zhang T. C.
Published: June 2012

As one kind of emerging contaminant, synthetic musks (SMs) are commonly used in varying amounts in many personal care products and have been detected in different environmental systems. Occurrence and fate of four common SMs [galaxolide (HHCB), tonalide (AHTN), musk xylene (MX) and musk ketone (MK)] were studied in different sewage treatment plants (STPs) of Shanghai, China among different seasons. Results showed that total dissolved concentrations of the four SMs were 536–3,173 ng/L in influent, 351–2,595 ng/L in effluent and 147–6,839 μg/kg dry weights in sludge. The SM concentrations varied with input sources, STP treatment processes, usage patterns, and different seasons or surveyed years of consumption. There was no significant removal of SMs in most of the sewage samples of the four STPs. Significant positive correlations were observed between concentrations of HHCB and AHTN (R2 = 0.9062, n = 12, p< 0.05), HHCB and MK (R2 = 0.7471, n = 8, p< 0.05), as well as AHTN and MK (R2 = 0.9321, n = 8, p< 0.05) in sludge samples.
Model-based quality management of groundwater resources – catchment area Liedern, Germany
Authors: Kübeck Christine , Hansen Carsten , König Christoph , Denzig Dorothea , van Berk Wolfgang
Published: June 2012

Strategies of groundwater protection in agricultural dominated areas are mainly based on a general reduction of the input of nutrients like nitrate. However, preventive measures in different parts of the catchment may provide very different effects on raw water quality. Exemplified on the case study ‘Liedern’ (BEW GmbH Bocholt, Germany) it is shown that hydrogeochemical processes along the flow path and in the well strongly affect the results of agricultural measures in terms of modality and efficiency. Thus, a reduction of fertilization in the vicinity of the well gallery leads to a decrease of nitrate concentration in the raw water. Whereas agricultural measures in the eastern part of the catchment do not influence nitrate, but cause a reduction of the iron concentration and rate of incrustation in the wells after 18 years. In this study we present a management tool that enables assessment of future trends in raw water quality. The tool is based on a reactive transport model which considers land use dynamics as an instrument to influence groundwater/raw water quality. A thermodynamic equilibrium approach is applied for modelling hydrogeochemical processes between aqueous, solid and gaseous phases. Kinetically controlled reactions like the microbial degradation of organic carbon are expressed by multiplicative Michaelis–Menten equations.
Fundamental nonlinearities of the reactor-settler interaction in the activated sludge process
Authors: Diehl Stefan , Farås Sebastian
Published: June 2012

The activated sludge process can be modelled by ordinary and partial differential equations for the biological reactors and secondary settlers, respectively. Because of the complexity of such a system, simulation models are most often used to investigate them. However, simulation models cannot give general rules on how to control a complex nonlinear process. For a reduced-order model with only two components, soluble substrate and particulate biomass, general results on steady-state solutions have recently been obtained, such as existence, uniqueness and stability of solutions. The aim of the present paper is to utilize those results to formulate some implications of practical importance. In particular, strategies are described for the manual control of the effluent substrate concentration subject to the constraint that the settler is maintained in normal operation (with a sludge blanket in the thickening zone) in steady state. Such strategies contain how the two control parameters, the recycle and waste volumetric flow ratios, should be chosen for any (steady-state) values of the input variables.
Energy losses at three-way circular drop manholes under surcharged conditions
Authors: Arao Shinji , Kusuda Tetsuya , Moriyama Katsumi , Hiratsuka Shunsuke , Asada Jyunsaku , Hirose Nozomu
Published: June 2012

Energy loss at manholes is of importance in the design of storm sewer networks and in flood-analysis. Some researchers have already investigated the energy loss at three-way manholes under surcharged conditions. However, formulation to calculate the energy loss at manholes, including all variables of structural elements of the pipes and of the manhole has not yet been accomplished. Therefore, more study to formulate the energy loss at three-way drop manholes is needed. In this study, the ratio of the diameter between inflow pipes and an outflow pipe, the ratio of flow rates between those pipes, water depth in a manhole and the drop gaps between those pipes are considered and the energy loss at three-way circular drop manholes is examined. Finally, a modified formula, more accurate than that in the U.S. Federal Highway Administration's 2001 Urban Drainage Design Manual is proposed. The proposed formula takes the influence of the ratio of the diameter between inflow pipes and outflow pipe and drop gaps between those pipes into consideration. The calculated energy loss coefficients in both straight-through and lateral pipes successfully reproduce the measured values.
Regional scale analysis for the design of storage tanks for domestic rainwater harvesting systems
Authors: Campisano A. , Modica C.
Published: June 2012

A regional scale analysis for the design of storage tanks for domestic rain water harvesting systems is presented. The analysis is based on the daily water balance simulation of the storage tank by the yield-after-spillage algorithm as tank release rule. Water balances are applied to 17 rainfall gauging stations in Sicily (Italy). Compared with literature existing methods, a novel dimensionless parameter is proposed to better describe the intra-annual character of the rainfall patterns. As a result, easy-to-use regional regressive models to evaluate the water saving performance and the overflow discharges from the tank are provided along with a stepwise procedure for practical application. The regional models demonstrate good fits between model predictions and simulated values of both water savings and overflows from the tank.
New Metrics for Assessing Diagnostic Potential of Candidate Biomarkers
Authors: Pickering John W. , Endre Zoltan H.
Published: June 2012

New tests should improve the diagnostic performance of available tests. The area under the receiver operator characteristic curve has been the “metric of choice” to quantify new biomarker performance. Two new metrics, the integrated discrimination improvement (IDI) and net reclassification improvement (NRI), have been rapidly adopted to quantify the added value of a biomarker to an existing test. These metrics require the development of risk prediction models that calculate the probability of an event for each individual. This study demonstrates the application of these metrics in 528 critically ill patients with risk models of AKI, sepsis, and 30-day mortality to which the biomarker urinary cystatin C was added. Analogous to the receiver operator characteristic curve, we present a new risk assessment plot for visualizing these metrics. The results showed that the NRI was sensitive to the choice of risk threshold. The risk assessment plot identified that the addition of urinary cystatin C to the model decreased the calculated risk for some who did not have sepsis but increased it for others. The category-free NRI for each outcome indicated that most of those without the event had reduced calculated risk. This was driven by very small changes in calculated risk in the AKI and death models. The IDI reflected those small changes. Of the new metrics, the IDI, reported separately for those with and without the events, best represents the value of a new test. The risk assessment plot identified differences in the models not apparent in any of the metrics.
Role of genetic resources from different geographic and climatic regions in simultaneous breeding for high quality protein maize (HQPM) and stress tolerance
Authors: Denic Miloje , Ignjatovic-Micic Dragana , Stankovic Goran , Markovic Ksenija , Zilic Sladjana , Lazic-Jancic Vesna , Chauque Pedro , Fato Pedro , Senete Constantino , Mariote David , Haag Wayne
Published: June 2012

Due to the low biological value of proteins of common maize, it was
reinitiated breeding for high protein quality maize (HQPM) using three
genetic systems, namely: opaque-2 gene, endosperm modifier genes and enhancer
genes, which are increasing lysine and tryptophan content in opaque-2
background In order to alleviate effect of abiotic and biotic stress factors,
the genotypes with tolerance to those factors were included. Genetic
resources originating from North, Central and South America, then West,
Central and Southern Africa and gene bank of Maize Research Institute ?Zemun
Polje? were used. Combining breeding approaches in selection of genetic
resources, field plot techniques and laboratory analysis, it was created
large number of early QPM varieties, inbred lines and hybrids with modified
endosperm and high yield potential under poor and good growing conditions.
Created lines exhibited high combining ability in conventional and
non-conventional hybrids. Yield trials showed that QPM hybrids are competing
with commercial hybrids of common maize.
Epidemiological characteristics of suicidal patients admitted to the psychiatric clinic in Kragujevac: A ten-year retrospective study
Authors: Ignjatovic-Ristic Dragana , Radevic Svetlana , Djokovic Danijela , Petrovic Dusan , Kocic Sanja , Ristic Branko , Zecevic-Lukovic Tanja
Published: June 2012

Introduction. Suicide attempts are a significant public health problem. They
are associated with significant morbidity and result in significant use of
health care resources. Objective. The aim of our study was to analyze
epidemiological characteristics attempts of suicide for persons in the period
2001-2010 who were hospitalized at the Psychiatric Clinic in Kragujevac after
the attempt of suicide. Methods. We analysed 286 clinical records of patients
who had attempted suicide (133 males, 153 females). We used the illness
history of patients, who were treated at the Psychiatric Clinic in Kragujevac
after their suicide attempts. We made the analysis of socio-demographic
characteristics of the sample and characteristics of the suicide act itself.
Results. Our results showed a higher rate of female population, except for
the period 2003-2005: 2003 - 14 males (58.3%), 2004 - 15 (62.5%) and 2005 -
60%. The largest number of attempts was in the population aged between 25 and
34 years (23.8%). The percentage of persons from urban areas was higher
(66.4%). Depressive disorder was a common pre-existing disorder before a
suicide attempt (42.3%). Most attempts of suicide were performed by
overdosing on medications (57.7%). Conclusion. In the last three years we
observed a decrease of suicide attempts. We noticed that middle aged persons
are the most frequent ones to attempt suicide. Depressive disorder is the
most frequent pre-existing condition of suicide attempt. In order to prevent
suicide attempts we must improve early detection of depressive disorder, as
well as initial treatment.
Quality of life of schizophrenic patients treated with haloperidol depot and injection preparation of long-lasting risperidone
Authors: Mihajlovic Goran , Jovanovic-Mihajlovic Natalija , Radmanovic Branimir , Radonjic Katarina , Djukic-Dejanovic Slavica , Jankovic Slobodan , Janjic Vladimir , Milovanovic Nebojsa , Petrovic Dusan , Tomic Katarina
Published: June 2012

Introduction. In the last decades psychiatric patients? quality of life
attracts great attention of researchers. Improving the quality of life of
schizophrenic patients is increasingly becoming an imperative in
pharmacological therapy. Objective. Analysis of certain aspects of quality of
life in patients with schizophrenia treated with depot formulations of a
typical antipsychotic (haloperidol) and injection preparation of a
long-acting atypical antipsychotic (risperidone). Methods. Research was
conducted as a cross-sectional study that included 60 patients of both
genders. Examinees diagnosed with schizophrenia (ICD-10, F20.0-F20.9) were
divided into two groups: the group of patients that received haloperidol
depot (n=30) and the group of patients that received injection preparation of
long-acting risperidone (n=30). In order to assess the quality of life,
social functioning scale (SFS), satisfaction with life scale (SWLS), and
short version of World Health Organization quality of life scale
(WHO-QoL-Brief) were applied. Results. Results showed statistically
significant differences when it comes to social activity and satisfaction
with life in favour of patients treated with injection preparation of
long-acting risperidone. Examinees from this group were much more satisfied
with themselves, their health and sleep compared to those on haloperidol
depot. There was no statistically significant difference found on the quality
of life scale. Conclusions. Applying the scales for the assessment of the
quality of life of schizophrenic patients in terms of psychosocial
functioning, statistically significant difference between groups was found.
Results showed higher scores in the group of patients treated with injection
preparation of long-acting risperidone concerning social activities and life
satisfaction.
Forensic psychiatric expertise: Posttraumatic stress disorder
Authors: Stojakovic Milan
Published: June 2012

Introduction. This article presents our experiences in the field of forensic
post-traumatic stress disorder (PTSD). Objective. The study examined
parameters of 30 patients with PTSD who were the subject of forensic
expertise (PTSDF) and in 30 patients with PTSD who were not (PTSDN). Methods.
Clinical research and the battery of tests (Impact of Event Scale - IES,
Mississippi Scale, and list of symptoms of PCL-M) covered a total of 60 male
subjects with a verified diagnosis of PTSD. The study involved
socio-demographic variables, catastrophic experience, enduring personality
change after catastrophic experience (EPCACE), comorbidity disorders and
non-material damage. Results. In terms of respondents? average age, years of
education, marital status, time of military engagement, there were no
statistically significant differences between PTSDF and PTSDN groups. In
terms of EPCACE statistically significant differences were found in both
PTSDF and PTSDN groups. Among PTSDF respondents (N=30) EPCACE was verified in
83.33% (N=25), and among PTSDN in 23.33% (N=7) (p<0.05). In terms of
comorbidity disorders and the parameter of non-material damage no
statistically significant differences were found either in PTSDF or PTSDN
group. Conclusion. In terms of EPCACE there were statistically significant
differences both in PTSDF and PTSDN group. Forensic and psychiatric meaning
of PTSD encompasses a number of complex elements on which forensic expert
opinion depends, while the existence of PTSD diagnosis itself does not affect
creation of opinions. The study should serve to identify methodological and
conceptual problems in the field of forensic aspects of PTSD.
Hetero-aggressive outbursts in patients’ behaviour in emergency psychiatry
Authors: Djokic-Pjescic Katarina , Ristic-Dimitrijevic Radmila , Nenadovic Milutin , Jovicic Slobodan , Nesic Sonja , Rajcic Tatjana , Vlaskovic Tatjana , Klidonas Nikolaos
Published: June 2012

Introduction. Hetero-aggressive behaviour in patients with mental disorders
is frequent and requires special skills of doctors and other medical staff in
order to urgently protect the patient and indicate hospitalization.
Objective. The objective of this paper was to examine the frequency of the
most common diagnostic categories in psychiatric patients with
hetero-aggressive behaviour. The secondary objective was to examine aspects
of realized hospitalization (voluntary, involuntary) and socio-demographic
characteristics of these patients. Methods. The sample was formed of 100
patients who expressed hetero-aggressive behaviour just before and during
admission for hospital treatment. The data was collected from auto-anamnesis
and hetero-anamnesis, and they were based on general somatic, neurological
and psychiatric examination. The statistical analysis used descriptive
analysis and Pearson?s ?2-test. Results. The frequency of the most common
diagnostic categories was: F20-F29 73%; F10-F19 19%; F60- F69 11%; F00-F09
8%; F30-F39 and F70-F79 6%. Involuntary hospitalization was implemented in
56%. Socio-demographic characteristics of examinees revealed that the most
common were: male gender (63%) and younger age, dominant secondary school
qualification (74%), unmarried (76%), unemployed (76%), frequently repeated
hospitalizations (66%). Conclusion. The most common diagnostic categories to
which the patients with hetero-aggressive behavioural outbursts belonged were
from the schizophrenic circuit, followed by substance abuse, personality
disorders, etc. Involuntary hospitalization was the most common form of
hospitalization in patients with violent behaviour. Socio-demographic
characteristics of examinees revealed this profile as the most common: male
gender, younger age, secondary education, unmarried and unemployed,
repeatedly hospitalized.