bluuebunny/crossref_metadata_2025 huggingface dataset:
Surfactant-Steam Process: An Innovative Enhanced Heavy Oil Recovery Method for Thermal Applications
Authors: Zeidani K. , Gupta S. C.
Published: June 2013

Surfactant-steam process (SSP) is a novel and potentially cost-effective process that utilizes a small amount of surfactant co- injected with steam to enhance the oil recovery of steam assisted gravity drainage (SAGD) well pairs. The mechanism of this process involves interfacial tension (IFT) reduction, reservoir rock wettability alteration, oil relative permeability enhancement, and in-situ emulsification.

SSP is expected to result in oil rate acceleration, steam-to-oil ratio (SOR) reduction and enhanced ultimate oil recovery factor. Analogous enhancement is expected if the SSP is combined with other steam-based or steam-solvent processes. This paper provides an introduction to this concept and presents a unique protocol that has been developed for screening surfactants for co-injection with steam in SAGD process. In particular, the paper presents a scientific approach to surfactant selection for SSP applications, describes the conditions in which the surfactants needs to be deployed within the reservoir, and also predicts the potential synergies if use of different classes of surfactants is made. Novel experimental design on different aspects of surfactant-steam phase behavior indicates the optimum surfactant concentrations for field trial

applications. Lab testing of selected surfactants on typical Canadian oilsands sand packs shows an improved incremental oil recovery factor (RF) in the range of 6 to 16% (for different tested surfactants) compared to a SAGD base case.

SSP simulations were conducted for one of the surfactants that were tested in the lab. The simulation results indicate that this particular surfactant on average accelerated the oil rate by 15% in the first 30 months of SSP operation, increased the ultimate oil RF by 10%, and reduced the cumulative steam-to-oil ratio (CSOR) by almost 11% relative to a SAGD base case. In addition, a sensitivity analysis was conducted to investigate the effect of surfactant concentration co-injected with steam. The simulation results suggest that there is an optimum concentration for a given surfactant that needs to be explored through lab investigations and field trials.

It is evident that once the SSP is successfully developed, the use of surfactant promises to improve environmental performance and project economics of the in-situ oilsands recovery.
A Performance Comparison Study of Electromagnetic Heating and SAGD Process
Authors: Liu Manyang , Zhao Gang
Published: June 2013

Downhole electrical heating has proven as an attractive alternative of lowering the oil viscosity by raising the temperature in the formation. Because reservoirs with characteristics such as extremely low permeability, very thin pay-zone, and extra-heavy oil are generally not feasible for steam injection based Enhanced Oil Recovery (EOR) techniques, and the application of low- frequency Electrical Resistance Heating (ERH) has been demonstrated to limit the heating rate as well as the production rate. Hence, high frequency Electromagnetic Heating (EMH) has been chosen as a potential candidate to a reservoir for which other thermal recovery techniques are not suitable. This study presents both an oil single phase radial flow and oil-gas two-phase linear flow EMH model with COMSOL. Result shows that EM heating is practicable and cost effective under certain constraints in the real field. Parametric study indicates that the cumulative oil production achieved by EMH can be enhanced by a similar EOR approach called Single Well Steam Assisted Gravity Drainage (SW-SAGD) simulated in STARS for reservoirs with the above mentioned characteristics.
Specifics and Challenges of Heavy oil Production in Northen Siberia Illustration Based on Biggest Heavy Oil Project in Russia
Authors: Aksenov M. , Lachugin D. , Nukhaev M. , Rymarenko K. , Telkov V. , Gaidukov L. , Vologodskiy K. , Khramov D.
Published: June 2013

Russkoye heavy oil field is located in the northern part of Siberia. The field was discovered in 1968. It is characterized by the huge reserves: more than 1.3 billion tonn of oil in place and remote location (the field is located to the north from the polar circle). Main challenges for the field development are: unconsolidated formation, gas cap, high heterogeneity of formation, permafrost zone and heavy oil.

This paper covers latest experience (2007-2012) obtained during field development pilot project implementation at the representative part of the Russkoye field. Pilot stage results will be used for the further field development strategy building. Effectiveness of different approaches has to be estimated, considering specifics of the field. Traditional field instrumentation did not provided reliable data for the analysis. New technologies (such as fiber optic distributed temperature sensors, specifically adopted multiphase metering etc.) were implemented for the building of the proper data acquisition system. During the pilot stage specific injection schedules, cold and hot water injection, various well completion applications were implemented. Depletion rate estimation based on real production data, determination of critical drawdown and numerous well testing activities including conventional buildup/drawdown pressure transient analysis and interference testing were made. Special attention is paid to the comparison of the cold and hot water injection and to the methods of control/monitoring of the well production. Monitoring and effectiveness estimation of the tested technology should be based on flow rate measurements data (MPFM), distributed pressure and temperature sensors (DP/TS) in horizontal production wells. Numerous new technologies were used for the pilot project. Paper describes approaches for integrated data acquisition implementation; development techniques comparison and new technologies adaptation workflow to the specific field conditions. New technologies application allowed to see specific field behavior and to estimate effect of various field development and management approaches tested.

The results obtained during the pilot project will be used for the Russkoye field development planning, technical solutions will be implemented for the field monitoring and managing. Successful development of the first biggest heavy oil field should lead to initiation of development of other numerous challenging heavy oil fields in Russia.
Data-Driven Modeling Approach for Recovery Performance Prediction in SAGD Operations
Authors: Amirian Ehsan , Leung Juliana Y. , Zanon Stefan , Dzurman Peter
Published: June 2013

Quantitative ranking of different operating areas and assessment of uncertainty due to reservoir heterogeneities are crucial elements in optimization of production and development strategies in oil sands operations. Although detailed compositional simulators are available for recovery performance evaluation for SAGD, the simulation process is usually deterministic, cumbersome, expensive (manpower and time consuming), and not quite suitable for real-time decision making and forecasting.

In this paper, Artificial Neural Network (ANN) is employed as a data-driven modeling alternative to predict SAGD recovery performance in heterogeneous reservoirs, an important application that is lacking in existing literature. In this study, numerical flow simulations are performed to construct a training data set consists of various attributes describing characteristics associated with reservoir heterogeneities and relevant production/injection parameters with the corresponding recovery factor as output. The network is trained using the data set to identify all significant patterns and relationships that exist between these attributes and the output parameters. The model is then tested using a verification data set (cases that have not been used at the training stage). Sensitivity studies on network configurations are also investigated. In addition, new modifications are proposed to identify and reduce extrapolations in predictions, which are often considered as major drawbacks in most data-driven modeling approaches.

The approach described in this paper can be integrated directly into most existing reservoir management routines. In addition, the technique can be used as a viable tool for analyzing large amount of competitor data efficiently. Given that robust forecasting and optimization of heavy oil recovery processes is a major challenge faced by the industry, the proposed research has great potential to be applied in other recovery projects such as solvent-additive steam injection.
Experimental Measurement of CO2 Solubility in heavy Oil and Its Diffusion Coefficient calculation at both Static and Dynamic Conditions
Authors: Kavousi Ali , Torabi Farshid , Chan Christine
Published: June 2013

With population growth, increasing world energy demand and depletion of conventional oil resources, exploiting heavy and extra-heavy oil reservoirs seems one of the promising options in supplying world oil request. However, there are several barriers to the rapid growth of production from such reservoirs.

CO2-based enhanced oil recovery (CO2-EOR) techniques are among processes utilized to enhance heavy oil and bitumen production. The design and modeling of CO2-EOR require extensive knowledge about the solubility and diffusivity of CO2 in heavy oil. Hence the primary objective of this research was to identify the main mechanisms involved in the static and dynamic mass transfer of CO2 into the heavy oil systems.

This experimental study commenced by allowing CO2 to be in contact at static condition with two different types of heavy oil having viscosities of 5000 and 20000 cP at 298 K. Experiments were conducted at three different initial pressures (1.73, 3.10, 4.49 mPa) and pressure decay concept was used to determine the CO2 solubility for each individual case. The experiments then were extended using a Mini-bench top reactor (PARR-4560) from Parr Instrument Company to repeat similar tests in dynamic condition. Using the reactor's stirrer, the oil was agitated at the velocity of 30 rpm; thereby a semi-flowing condition was generated leading a convection effect in the oil bulk phase. For both dynamic and static conditions, the proper mathematical model were proposed and solved numerically to determine the diffusion coefficient value at each specific operating condition.

Results showed that the solubility of CO2 at initial pressure of 1.73 mPa for 5000cP oil is 0.04015, and 0.04195 g/100cc for static and dynamic conditions, respectively. The diffusion coefficient value at static and dynamic condition for the same experimental condition is 4.531×10-10 m/s2 and 4.852×10-10 m/s2. Experimental and mathematical interpretations of other cases showed similar behaviour. From the results at both conditions it can be obtained that the initial pressure has significant effect on reaching the stability condition and longer time is required for higher pressures. Moreover, diffusion coefficient is more sensitive to oil viscosity rather than ultimate solubility value.
History Matching Grosmont C Carbonate Thermal Production Performance
Authors: Qi Jinxiu , Yuan Jian-Yang
Published: June 2013

The Devonian Grosmont Formation is a bitumen saturated carbonate unit located in northern Alberta. It is considered to be Canada's second largest unconventional oil resource after the McMurray Formation oil sands. Production from the Grosmont Formation has been tested by a consortium of Unocal, Canadian Superior, AOSTRA, Chevron and other companies between 1970's to 1980's with some success and significant learning. Since 2010, Laricina Energy Ltd. and Osum Oil Sands Corp. have started a new wave of testing thermal recovery processes for the Grosmont Formation using horizontal wells. The Grosmont C carbonate reservoir contains vugs and fractures at multiple scales, and thus has a different porosity and permeability network than the clastic oil sands. This paper describes a numerical simulation approach to history matching the performance of one of the pilot wells in order to better characterize reservoir properties such as fractures and vugs at multiple scales and their interactions with the rock matrix. CMG's STARS dual porosity dual permeability module was used to simulate this complex system. The results of the simulation suggest that small-scale vugs should be combined with the matrix in order to obtain a better history match of the reservoir and production performance. Parameters describing fracture properties have become critical not only in matching the well behavior, but also in matching reservoir thermal responses. Advantages, limitations, and recommendations for using a dual porosity and dual permeability model for understanding a multiple-scale porous and permeability system are also discussed.
A New Method to Extract In-situ Bitumen From Core Samples
Authors: Zhao Hongying , Gao Jinglin , Jia Na , Memon Afzal , Ringen Jon Knut , Yang Tao , Larsen Jarle , Tollefsen Svein
Published: June 2013

A common challenge in fluid studies involving heavy oil, and bitumen in particular, is obtaining an in-situ bitumen sample from the highly viscous reservoirs that is water and solid free. In this paper, a salt-water assisted centrifugation (SWAC) method that was developed to effectively extract in-situ bitumen suitable for fluid studies from core samples is presented.

The method involved mixing salt water with core sample pieces at a defined ratio. The mixture was then centrifuged at 50°C to separate the bitumen from the water and sand. The result was a clean bitumen sample containing less than 1 wt% of water and 0.1 wt% of sediment and a recovery rate of approximately 90 wt%.

The properties of the recovered bitumen were characterized and compared with the properties of another bitumen sample that had been extracted by the mechanical squeeze (MS) method in order to understand how the salt and water used during the process may have impacted the chemical and physical properties of the bitumen sample. The experimental data showed that most of the properties of the two bitumen samples were similar with the exception of a slight variation in measured viscosities at various temperatures. The reasons for these measured viscosity differences are discussed.

When compared to commercialized methodologies for removing bitumen samples from cores, such as solvent extraction, MS and hot water/steam flooding methods, the presented solvent free method is characterized for its high bitumen recovery rate and high bitumen sample quality. The SWAC method offers an efficient alternative for extracting in-situ bitumen samples in quantities sufficient for fluid related studies.
Design and Field Evaluation of Tubing Deployed Passive Outflow Control Devices in SAGD Injection Wells
Authors: Medina Max
Published: June 2013

The integration of horizontal wells and thermal oil recovery methods, such as Steam Assisted Gravity Drainage (SAGD), has enabled the economic exploitation of extra-heavy oil resources, mainly in Canada. The use of passive outflow control devices (OCDs) in SAGD wells adds steam injection points along the horizontal wellbore influencing steam placement and chamber growth; thus, potentially reducing the steam-to-oil ratio (SOR), productivity uncertainty and accelerating production.

For designing OCD installations in SAGD, we need to address two main aspects. Firstly, the interface between horizontal wellbore hydraulics and reservoir injectivity that allows determining the optimum number and location of the steam injection points. Secondly, the design of the OCD itself, which involves selecting and configuring the device with a hydraulic performance that is fit for purpose. For this study we will focus specifically on straight-orifice choke passive OCDs.

This paper presents a comprehensive design methodology for tubing deployed passive OCDs in SAGD. The completion design is carried out with a steady-state model of the injection well using a commercial thermal wellbore simulator.

The field performance evaluation of tubing deployed passive OCDs is critical for verifying the effectiveness of the design methodology and the hydraulic performance of the devices under real field conditions. The field evaluation is done by history matching the injection pressure vs. steam rate data with a model developed in the thermal wellbore simulator. A dynamic pressure gradient (under flowing conditions) in the injection string carrying the OCDs is obtained with a temperature log, taken with fiber optic technology, where the temperature data is converted to pressure by virtue of the properties of saturated steam. This approach is new for the SAGD industry.

The OCDs hydraulic field performance was successfully matched with the simulated model, which indicates the effectiveness of the design methodology, the field performance evaluation techniques and the effectiveness of the OCDs in delivering the desired amount of steam at each location.
Improve Economy of Oil Sands Reservoir Development by Integrating Reservoir Simulation with Economic Evaluation
Authors: Gu Fagang , LaPlante Hannah , Bergen David , Tachet Eric , Ferrarella Francesco
Published: June 2013

The development of oil sands reservoirs with Steam Assist Gravity Drainage (SAGD) is a capital intensive investment. It is crucial to improve the economic value through all aspects of the value chain, from reservoir, facility to end selling points. There are many studies focusing on optimizing the performance of single SAGD well pairs. However, few are looking into optimizing the overall economy of the development of large scale oil sands reservoirs.

This paper presents a case study of the value improvement process of an Athabasca oil sands reservoir to be developed with the SAGD process. The reservoir has various quality and a size of accommodating about 200 well pairs with 100m well spacing and 800m well length. The purpose of this paper is not to cover all value improvement aspects but from a subsurface engineering point of view to optimize reservoir development and production operation parameters to improve the overall reservoir development value. The investigated parameters include well spacing, steam injection pressure, artificial lift method, wind-down and blow-down criteria, and minimum oil rate of edge wells. In the process, reservoir simulation is fully integrated with economic evaluation. The optimization and decision are made based on economic assessment results, operation requirements and environmental benefits. In the value improvement process, both type well and full field reservoir simulation were used to forecast full field production for economic evaluation. Since the pad sequence also plays an important role in the reservoir development economy, to improve Net Present Value (NPV), a simple SAGD economic index is proposed and applied for pad ranking. The ranking results are compared with the pad-by-pad economic evaluation that included all economic elements but taxes. Through all these efforts, the NPV of the project was significantly improved.
Effect of No‐Till and Extended Rotation on Nutrient Losses in Surface Runoff
Authors: Shipitalo Martin J. , Owens Lloyd B. , Bonta James V. , Edwards William M.
Published: June 2013

No‐till crop production can reduce soil erosion compared to conventional tillage, but there is concern that lack of fertilizer incorporation will increase loss of dissolved nutrients in surface runoff. Therefore, we compared nutrient and sediment loss from two no‐till and two chisel‐till small (0.45–0.79 ha) watersheds managed in a 2‐yr corn (Zea maysL.)/soybean [Glycine max(L.) Merr]–rye (Secale cerealeL.) cover crop rotation for 16 crop years. We also investigated the effect of replacing some of the mineral N with manure and red clover by monitoring runoff from three watersheds in a 3‐yr corn/soybean/wheat–red clover (Triticum aestivumL.–Trifolium pratenseL.) extended rotation. The reduced‐input watersheds were disked in corn and soybean years. For all tillage treatments, NO3–N losses were greatest with corn and averaged from 3.7 (no‐till) to 5.5 kg ha−1yr−1(chisel) for all crop years. Average dissolved P losses were 0.21 kg ha−1yr−1(chisel), 0.32 kg ha−1yr−1(no‐till), and 0.84 kg ha−1yr−1(reduced‐input). Total P losses were least from no‐till (0.79 kg ha−1yr−1), intermediate for chisel (0.84 kg ha−1yr−1), and greatest for reduced‐input watersheds (1.68 kg ha−1yr−1). Soil loss was least from no‐till (807 kg ha−1yr−1), intermediate from chisel (1073 kg ha−1yr−1), and greatest from reduced‐input watersheds (1177 kg ha−1yr−1). Thus, no‐till had only slightly greater dissolved P losses compared to chisel, but had smaller soil, NO3–N, and total P losses. The greater dissolved and total P losses, as well as greater soil loss, compared to chisel and no‐till watersheds, indicated that there was no surface water quality benefit to the reduced‐input extended rotation.
Inhibition effect of phosphorus-based chemicals on corrosion of carbon steel in secondary-treated municipal wastewater
Authors: Shen Zhanhui , Ren Hongqiang , Xu Ke , Geng Jinju , Ding Lili
Published: June 2013

Secondary-treated municipal wastewater (MWW) could supply a viable alternative water resource for cooling water systems. Inorganic salts in the concentrated cooling water pose a great challenge to corrosion control chemicals. In this study, the inhibition effect of 1-hydroxy ethylidene-1,1-diphosphonic acid (HEDP), trimethylene phosphonic acid (ATMP) and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA) on corrosion of carbon steel in secondary-treated MWW was investigated by the means of potentiodynamic polarization and electrochemical impedance spectroscopy. The inhibition effect increased with increasing concentration of inhibitors. The corrosion rates of carbon steel were 1.5, 0.8, 0.2 and 0.5 mm a–1 for blank, HEDP, ATMP and PBTCA samples at 50 mg L–1, respectively. The phosphorus-based chemicals could adsorb onto the surface of the carbon steel electrode, form a coat of protective film and then protect the carbon steel from corrosion in the test solution.
Saturated and unsaturated flow through sloped compost filter beds of different particle sizes
Authors: Petrell R. J. , Gumulia Anastasia
Published: June 2013

Little is known about the hydraulics of sloped compost beds having active free and non-flowing zones, and used for runoff erosion and volume control, and heavy metal removal. Water sorption tests on yard waste compost indicated that water transfer between the two zones would be slow (6 hr for a 0.04 m rise). The free flowing zone in ≈1 m long sloped (15°) beds increased in depth (0.01–0.08 m) with decreasing particle size and increasing flow. Particle size and flow (0.08–0.3 L/s/m) affected bed stability. Drainage volume increased with flow while drainage time remained fairly constant. Saturated flow occurred depending on the particle size above 0.02–0.165 L/s/m. Data indicate that sheet runoff from low intensity storms would most likely create unsaturated but stable bed conditions. Concentrated flows as from downspouts would likely create saturated conditions and have to be managed to prevent washout. A model based on porous media theory indicated that flow regime under saturated flow is turbulent. Results can be used to design compost beds for various runoff rates and to develop a heavy metal sorption model.
The interaction between natural organic matter in raw waters and pesticide residues: a three dimensional excitation–emission matrix (3DEEM) fluorescence investigation
Authors: Beale David J. , Porter Nichola A. , Roddick Felicity A.
Published: June 2013

This paper examines the interaction between dissolved natural organic matter and pesticide residues, both of which are found in raw water sources, using three dimensional excitation–emission matrix (3DEEM) fluorescence spectroscopy. It was observed that pesticide residue at 0.1 mg L−1 formed a complex with humic-like fluorophores that are commonly found in raw water samples. Applying 3DEEM fluorescence to investigate the humic fractions, it was found that identification of changes in water sources was possible, and, importantly, the presence of a number of pesticides was able to be determined. In addition, the formation of this complex, and the influence of soluble cations and anions upon it, was shown to impact the efficiency of analytical extraction procedures for pesticides; however, 3DEEM fluorescence could be an approach to account for such losses.
Comparison of core sampling and visual inspection for assessment of concrete sewer pipe condition
Authors: Stanić N. , de Haan C. , Tirion M. , Langeveld J. G. , Clemens F. H. L. R.
Published: June 2013

Sewer systems are costly to construct and even more costly to replace, requiring proper asset management. Sewer asset management relies to a large extent on available information. In sewer systems where pipe corrosion is the dominant failure mechanism, visual inspection by closed circuit television (CCTV) and core sampling are among the methods mostly applied to assess sewer pipe condition. This paper compares visual inspection and drill core analysis in order to enhance further understanding of the limitations and potentials of both methods. Both methods have been applied on a selected sewer reach in the city of The Hague, which was reportedly subject to pipe corrosion. Results show that both methods, visual inspection and core sampling, are associated with large uncertainties and that there is no obvious correlation between results of visual inspection and results of drill core analysis.
Preparation of cationic waste paper and its application in poisonous dye removal
Authors: Yang Fan , Song Xiaojie , Yan Lifeng
Published: June 2013

Cationic paper was prepared by reaction of paper with 2,3-epoxypropyltrimethylammonium chloride in aqueous suspension, and tested as low-cost adsorbent for wastewater treatment. The experimental results revealed that anionic dyes (Acid Orange 7, Acid Red 18, and Acid Blue 92) were adsorbed on the cationic paper nicely. The maximum amount of dye Acid Orange 7 adsorbed on cationic paper was 337.2 mg/g in experimental conditions. The effects of initial dye concentration, temperature, and initial pH of dye solution on adsorption capacity of cationic paper were studied. The pseudo-first-order and pseudo-second-order kinetic models were applied to describe the kinetic data. The Freundlich and Langmuir adsorption models were used to describe adsorption equilibrium. The thermodynamic data indicated that the adsorption process of dye on cationic paper occurred spontaneously.
Sewage sludge solubilization by high-pressure homogenization
Authors: Zhang Yuxuan , Zhang Panyue , Guo Jianbin , Ma Weifang , Fang Wei , Ma Boqiang , Xu Xiangzhe
Published: June 2013

The behavior of sludge solubilization using high-pressure homogenization (HPH) treatment was examined by investigating the sludge solid reduction and organics solubilization. The sludge volatile suspended solids (VSS) decreased from 10.58 to 6.67 g/L for the sludge sample with a total solids content (TS) of 1.49% after HPH treatment at a homogenization pressure of 80 MPa with four homogenization cycles; total suspended solids (TSS) correspondingly decreased from 14.26 to 9.91 g/L. About 86.15% of the TSS reduction was attributed to the VSS reduction. The increase of homogenization pressure from 20 to 80 MPa or homogenization cycle number from 1 to 4 was favorable to the sludge organics solubilization, and the protein and polysaccharide solubilization linearly increased with the soluble chemical oxygen demand (SCOD) solubilization. More proteins were solubilized than polysaccharides. The linear relationship between SCOD solubilization and VSS reduction had no significant change under different homogenization pressures, homogenization cycles and sludge solid contents. The SCOD of 1.65 g/L was solubilized for the VSS reduction of 1.00 g/L for the three experimental sludge samples with a TS of 1.00, 1.49 and 2.48% under all HPH operating conditions. The energy efficiency results showed that the HPH treatment at a homogenization pressure of 30 MPa with a single homogenization cycle for the sludge sample with a TS of 2.48% was the most energy efficient.
Nitrous oxide formation during nitritation and nitrification of high-strength wastewater
Authors: Schneider Yvonne , Beier Maike , Rosenwinkel Karl-Heinz
Published: June 2013

The purpose of this study was to investigate the formation of nitrous oxide (N2O) in nitritation and nitrification under stable, comparable and not limiting conditions typical for treatment of high-strength wastewater. A laboratory-scale aerated chemostat was operated with reject water at different sludge retention times, achieving suppression of nitrate formation by wash-out of nitrite-oxidizing bacteria for nitritation. The N2O formation factor during stable nitritation was higher (2.90% N2O-N /NH4−-Nox) than during nitrification (0.74%). The positive correlation of N2O formation rates and ammonium oxidation rates was linear and thus did not contribute to changes of the N2O formation factor. The dominant factor for N2O formation during stable operation was high nitrite concentration, which was positively correlated with N2O formation rates. The highest formation factors were observed during a transition phase from nitrification to nitritation with unstable process conditions (4.81%) and during a short-term experiment with increased pH of 7 (10.28%). The results indicate that even with operational conditions that are regarded favourable for the process of nitritation N2O formation can be limited but not avoided.
Rethinking wastewater characterisation methods for activated sludge systems – a position paper
Authors: Choubert Jean-Marc , Rieger Leiv , Shaw Andrew , Copp John , Spérandio Mathieu , Sørensen Kim , Rönner-Holm Sabine , Morgenroth Eberhard , Melcer Henryk , Gillot Sylvie
Published: June 2013

Increasingly stringent effluent limits and an expanding scope of model system boundaries beyond activated sludge has led to new modelling objectives and consequently to new and often more detailed modelling concepts. Nearly three decades after the publication of Activated Sludge Model No1 (ASM1), the authors believe it is time to re-evaluate wastewater characterisation procedures and targets. The present position paper gives a brief overview of state-of-the-art methods and discusses newly developed measurement techniques on a conceptual level. Potential future paths are presented including on-line instrumentation, promising measuring techniques, and mathematical solutions to fractionation problems. This is accompanied by a discussion on standardisation needs to increase modelling efficiency in our industry.
Factors affecting microbial fuel cell acclimation and operation in temperate climates
Authors: Michie I. S. , Kim J. R. , Dinsdale R. M. , Guwy A. J. , Premier G. C.
Published: June 2013

For the successful scale-up of microbial fuel cell (MFC) systems, enrichment strategies are required that not only maximise reactor performance but also allow anodic biofilms to be robust to environmental change. Cluster analysis of Denaturing Gradient Gel Electrophoresis community fingerprints showed that anodic biofilms were enriched according to substrate type and temperature. Acetate produced the highest power density of 7.2 W m−3 and butyrate the lowest at 0.29 W m−3, but it was also found that the trophic conditions used to acclimate the electrogenic biofilms also determined the MFC response to different substrate types, with both acetate and butyrate substrates recording power densities of 1.07 and 1.0 W m−3 respectively in a sucrose enriched reactor. When temperature perturbations were introduced to investigate the stability of the different substrate acclimated electrogenic biofilms, the 20 °C acclimated acetate reactor was unaffected by 10 °C operation but all reactors acclimated at 35 °C were adversely affected. When the operating temperature was raised back to 35 °C both the acetate and butyrate reactors recovered electrogenic activity but the sucrose reactor did not. It is thought that this was due to the more complex syntropic interactions that are required to occur when metabolising more complex substrate types.
Lumped Element Electrical Model based on Three Resistors for Electrical Impedance in Radiofrequency Cardiac Ablation: Estimations from Analytical Calculations and Clinical Data
Authors: Berjano Enrique , d'Avila Andre
Published: June 2013

The electrical impedance measured during radiofrequency cardiac ablation (RFCA) is widely used in clinical studies to predict the heating evolution and hence the success of the procedure. We hypothesized that a model based on three resistors in series can mimic the total electrical impedance measured during RFCA. The three resistors or impedances are given by: impedance associated with the tissue around the active electrode (myocardium and circulating blood) (Z-A), that associated with the tissue around the dispersive electrode (Z-DE) and that associated with the rest of the body (Z-B). Our objective was to quantify the values associated with these three impedance types by an analytical method, after which the values obtained would be compared to those estimated from clinical data from previous studies. The results suggest that an RFCA using a 7 Fr 4-mm electrode would give a Z-A of around 75 ohms, a Z-DE around 20 ohms, and Z-B would be 15±10 ohms (for body surface area variations between 1.5 and 2.5 m^2). Finally, adaptations of the proposed model were used to explain the results of previous clinical studies using a different electrode arrangement, such as in bipolar ablation of the ventricular septum.
Combined Heart Rate– and Accelerometer-Assessed Physical Activity Energy Expenditure and Associations With Glucose Homeostasis Markers in a Population at High Risk of Developing Diabetes
Authors: Hansen Anne-Louise S. , Carstensen Bendix , Helge Jørn W. , Johansen Nanna B. , Gram Bibi , Christiansen Jens S. , Brage Søren , Lauritzen Torsten , Jørgensen Marit E. , Aadahl Mette , Witte Daniel R. ,   ADDITION-Denmark Steering Committee
Published: June 2013

OBJECTIVE

Regular physical activity (PA) reduces the risk of developing type 2 diabetes, and different subtypes of dysglycemia have shown different associations with PA. To better understand the associations of PA and glucose homeostasis, we examined the association of objectively measured PA energy expenditure (PAEE) with detailed measures of glucose homeostasis.

RESEARCH DESIGN AND METHODS

In 1,531 men and women, with low to high risk of developing type 2 diabetes, we measured 7 days of PAEE using a combined accelerometry and heart rate monitor (ActiHeart). Measures and indices of glucose homeostasis were derived from a 3-point oral glucose tolerance test in addition to measures of long-term glycemia (glycated hemoglobin A1c and advanced glycation end products). Associations of PAEE with glucose homeostasis markers were examined using linear regression models.

RESULTS

Median age (IQR) was 66.6 years (62.1–71.6) (54% men) with a median ActiHeart wear time of 6.9 days (6.0–7.1) and PAEE level of 33.0 kJ/kg/day (23.5–46.1). In fully adjusted models, we found higher levels of PAEE to be positively associated with insulin sensitivity and negatively with insulin 2 h after glucose load (P < 0.05).

CONCLUSIONS

Even in an elderly population with low levels of PA, we found higher objectively measured PAEE levels to be associated with a more beneficial glucose metabolic profile. Although our findings are cross-sectional, they indicate that even without high-intensity exercise, increasing the overall level of PAEE slightly in an entire population at risk for developing type 2 diabetes may be a realistic and worthwhile goal to reach in order to achieve beneficial effect in terms of glucose metabolism.
Effect of Intensive Lifestyle Intervention on Sexual Dysfunction in Women With Type 2 Diabetes
Authors: Wing Rena R. , Bond Dale S. , Gendrano Isaias Noel , Wadden Thomas , Bahnson Judy , Lewis Cora E. , Brancati Frederick , Schneider Stephen , Kitabchi Abbas E. , Van Dorsten Brent , Rosen Raymond C. ,   the Sexual Dysfunction Subgroup of the Look AHEAD Research Group
Published: June 2013

OBJECTIVE

Sexual dysfunction is a prevalent problem in obese women with type 2 diabetes. This study examined the effects of intensive lifestyle intervention (ILI) in these women.

RESEARCH DESIGN AND METHODS

Look AHEAD is a 16-center, randomized, controlled trial evaluating the health effects of ILI compared with a control group (diabetes support and education [DSE]). The Look AHEAD Sexual Function Ancillary study included 375 female participants at five Look AHEAD sites. Participants completed the Female Sexual Function Inventory (FSFI) and Beck Depression Inventory (BDI), and assessments of weight and cardiovascular risk factors at baseline and 1 year were made.

RESULTS

At baseline, 50% of the 229 participants who reported being sexually active met criteria for female sexual dysfunction (FSD); only BDI score was related to FSD. One-year weight losses were greater in the ILI group than in the DSE group (7.6 vs. 0.45 kg; P < 0.001). Among women with FSD at baseline, those in the ILI group (N = 60) compared with those in the DSE group (N = 53) were significantly more likely to remain sexually active (83 vs. 64%; P < 0.008), reported greater improvement in total FSFI scores and in most FSFI domains (P < 0.05), and were more likely to experience remission of FSD (28 vs. 11%; P < 0.04) at 1 year. No significant differences between ILI and DSE were seen in women who did not have FSD at baseline.

CONCLUSIONS

Participation in ILI appeared to have beneficial effects on sexual functioning among obese women with diabetes, particularly in those who had FSD at baseline.
On Asymmetric Distances
Authors: Mennucci Andrea C.G.
Published: June 2013

In this paper we discuss asymmetric length structures and
asymmetric metric spaces.
A length structure induces a (semi)distance function; by using
the total variation formula, a (semi)distance function induces a
length. In the first part we identify a topology in the set of paths
that best describes when the above operations are idempotent.
As a typical application, we consider the length of paths
defined by a Finslerian functional in Calculus of Variations.
In the second part we generalize the setting of General metric spaces
of Busemann, and discuss the newly found aspects of
the theory: we identify three interesting classes of paths, and
compare them; we note that a geodesic segment (as defined
by Busemann) is not necessarily continuous in our setting;
hence we present three different notions of intrinsic metric
space.
Association Between Foot Type and Lower Extremity Injuries: Systematic Literature Review With Meta-analysis
Authors: Tong Jasper W.K. , Kong Pui W.
Published: June 2013

Study Design

Systematic literature review with meta-analysis.

Objectives

To investigate the association between nonneutral foot types (high arch and flatfoot) and lower extremity and low back injuries, and to identify the most appropriate methods to use for foot classification.

Methods

A search of 5 electronic databases (PubMed, Embase, CINAHL, SPORTDiscus, and ProQuest Dissertations and Theses), Google Scholar, and the reference lists of included studies was conducted to identify relevant articles. The review included comparative cross-sectional, case-control, and prospective studies that reported qualitative/quantitative associations between foot types and lower extremity and back injuries. Quality of the selected studies was evaluated, and data synthesis for the level of association between foot types and injuries was conducted. A random-effects model was used to pool odds ratio (OR) and standardized mean difference (SMD) results for meta-analysis.

Results

Twenty-nine studies were included for meta-analysis. A significant association between nonneutral foot types and lower extremity injuries was determined (OR = 1.23; 95% confidence interval [CI]: 1.11, 1.37; P<.001). Foot posture index (OR = 2.58; 95% CI: 1.33, 5.02; P<.01) and visual/physical examination (OR = 1.17; 95% CI: 1.06, 1.28; P<.01) were 2 assessment methods using distinct foot-type categories that showed a significant association with lower extremity injuries. For foot-assessment methods using a continuous scale, measurements of lateral calcaneal pitch angle (SMD, 1.92; 95% CI: 1.44, 2.39; P<.00001), lateral talocalcaneal angle (SMD, 1.36; 95% CI: 0.93, 1.80; P<.00001), and navicular height (SMD, 0.34; 95% CI: 0.16, 0.52; P<.001) showed significant effect sizes in identifying high-arch foot, whereas the navicular drop test (SMD, 0.45; 95% CI: 0.03, 0.87; P<.05) and relaxed calcaneal stance position (SMD, 0.49; 95% CI: 0.01, 0.97; P<.05) displayed significant effect sizes in identifying flatfoot. Subgroup analyses revealed no significant associations for children with flatfoot, cross-sectional studies, or prospective studies on high arch.

Conclusions

High-arch and flatfoot foot types are associated with lower extremity injuries, but the strength of this relationship is low. Although the foot posture index and visual/physical examination showed significance, they are qualitative measures. Radiographic and navicular height measurements can delineate high-arch foot effectively, with only anthropometric measures accurately classifying flatfoot.

Level of Evidence

Prognosis, level 2a. J Orthop Sports Phys Ther 2013;43(10):700–714. Epub 11 June 2013. doi:10.2519/jospt.2013.4225
The Effectiveness of Postoperative Physical Therapy Treatment in Patients Who Have Undergone Arthroscopic Partial Meniscectomy: Systematic Review With Meta-analysis
Authors: Dias Josilainne Marcelino , Mazuquin Bruno Fles , Mostagi Fernanda Queiroz Ribeiro Cerci , Lima Tarcísio Brandão , Silva Mônica Angélica Cardoso , Resende Bruna Nogueira , da Silva Rodrigo Matsuoka Borges , Lavado Edson Lopes , Cardoso Jefferson Rosa
Published: June 2013

Study Design

Systematic review with meta-analysis.

Objectives

To evaluate the effectiveness of postoperative physical therapy treatment for patients who have undergone arthroscopic partial meniscectomy.

Background

There is no consensus on which treatment is best for patients post meniscectomy.

Methods

A search for articles published from 1950 to March 2013 was conducted in the MEDLINE, Embase, CINAHL, LILACS, SciELO, IBECS, Scopus, Web of Science, PEDro, Academic Search Premier, and Cochrane Central Register of Controlled Trials databases. The key words were physiotherapy, physical therapy modalities, exercise therapy, rehabilitation, knee, placebo, groups, tibial meniscus, meniscus, arthroscopy, meniscectomy, partial meniscectomy, randomized controlled trial, controlled clinical trial, randomized, systematic review, and meta-analysis.

Results

Eighteen randomized controlled trials were included in the review, 6 of which were included in the meta-analysis. Outpatient physical therapy plus a home exercise program, compared to a home program alone, improved function compared to a home program alone (mean difference, 10.3; 95% confidence interval: 1.3, 19.3; P = .02) and knee flexion range of motion (mean difference, 9.1; 95% confidence interval: 3.7, 14.5; P = .0009). Inpatient physical therapy alone compared to inpatient plus outpatient physical therapy reduced the likelihood of effusion (odds ratio = 0.25; 95% confidence interval: 0.10, 0.61; P = .003).

Conclusion

Physical therapy associated with home exercises seems to be effective in improving patient-reported knee function and range of motion in patients post-arthroscopic meniscectomy, although the included randomized controlled trials were classified from moderate to high risk of bias and should be interpreted with caution.

Level of Evidence

Therapy, level 1a-. J Orthop Sports Phys Ther 2013;43(8):560–576. Epub 11 June 2013. doi:10.2519/jospt.2013.4255
Are Joint Injury, Sport Activity, Physical Activity, Obesity, or Occupational Activities Predictors for Osteoarthritis? A Systematic Review
Authors: Richmond Sarah A. , Fukuchi Reginaldo K. , Ezzat Allison , Schneider Kathryn , Schneider Geoff , Emery Carolyn A.
Published: June 2013

Study Design

Systematic review with meta-analysis.

Objectives

To identify risk factors for osteoarthritis (OA) of the knee, hip, and ankle, including joint injury, sport, physical activity, overweight/obesity, and occupational activity, in all age groups.

Background

OA is a significant health problem worldwide, affecting up to 10% of men and 18% of women over 60 years of age. There has not been a comprehensive review examining modifiable physical risk factors associated with the onset of OA. This evidence is important to inform the physiotherapy management of individuals following onset of OA.

Methods

Twelve electronic databases were systematically reviewed. The studies selected met the following criteria: (1) original data; (2) joint injury, sport activity, physical activity, overweight/obesity, and/or occupational activity investigated as risk factors; (3) outcomes included OA (hip, knee, and/or ankle); and (4) analytic component of study design. The data extracted included study design, years of follow-up, study population, OA definition, risk factors, and results (effect estimates reported or calculated where available). The quality of evidence was assessed based on a modified version of the Downs and Black checklist.

Results

Joint injury, obesity, and occupational activity were associated with an increased risk of OA of the knee and hip. Sport and physical activity produced inconsistent findings. Joint injury was identified as a significant risk factor for knee OA (combined odds ratio = 3.8; 95% confidence interval: 2.0, 7.2) and hip OA (combined odds ratio = 5.0; 95% confidence interval: 1.4, 18.2), as was previous meniscectomy with or without anterior cruciate ligament injury for knee OA (combined odds ratio = 7.4; 95% confidence interval: 4.0, 13.7). There is a paucity of research examining risk factors associated with ankle OA; this review identified only 2 studies with this outcome.

Conclusion

Joint injury, obesity, and occupational activity are associated with an increased risk of knee and hip OA. Some findings remain inconclusive, including levels of physical activity and sport specificity in individuals who do not suffer an injury. Early identification of individuals at risk for OA provides an opportunity for physiotherapy management or other interventions to modify risk-related behavior. There is a need in the literature for additional high-quality studies, such as prospective cohort studies, that minimize potential bias in examining the relationship between physical risk factors and OA.

Level of Evidence

Prognosis, level 2a-. J Orthop Sports Phys Ther 2013;43(8):515–524. Epub 11 June 2013. doi:10.2519/jospt.2013.4796
Teleanalysis
Authors: Bennington Geoffrey
Published: June 2013

The telephone is taken as a privileged figure for discussing the relationship between Cixous and Derrida, particularly as it figures in some of Cixous's late work, and especially Hyperdream. It is suggested that the telephonic relation essentially involves interruption as well connection, and that this structure leads to reformulations of issues such as possibility and impossibility, life and death.