bluuebunny/crossref_metadata_2025 huggingface dataset:
New Advances in Physical Metallurgy
Authors: Hibbard WR
Published: March 2009

The use of metals and alloys depends upon a unique set of properties which best satisfy specific conditions of end-use. The critical properties involved are usually a combination of several independent ones such as cost, availability, ease of fabrication, and last, but most important, physical or chemical properties such as strength, electrical conductivity, magnetic characteristics, or corrosion resistance. These latter properties are often structure-sensitive; that is, the physical or chemical properties are controllable by changing the atomic or the micrographic structure of the material. By atomic structure is meant the arrangement of the atoms, and by micrographic structures is meant the arrangement of the crystals, the phases, and the components.
Trials and Tribulations of Large-Development Oil Heating
Authors: Edmands NM
Published: March 2009

In the original Levittown development on Long Island there are about 18,000 homes within a confined radius of approximately 6 miles. These homes are equipped with three variations of oil-burning equipment—rotary, high-pressure gun, and a low-pressure-type furnace, with oil rates ranging from 1/2 to 1 gal per hr. The furnace is located in the kitchen, so obviously proper and clean combustion is a must, and this, of course, ties in with clean fuel oil. In our case, we probably should discuss customer stability rather than oil stability. When you have a concentration of customers in such close proximity, they become very folksy and discuss the daily happenings. Very often we may receive calls from neighbors on the same day for the same cause, although only one has a legitimate complaint.
Do We Need a Stability Specification for No. 2 Heating Oil?
Authors: Gray R
Published: March 2009

It would be desirable to have included in the specifications for No. 2 heating oil some measure of the stability characteristics of the fuel. This is the opinion of a substantial group of fuel oil marketers in eight states who cooperated with the author in a questionnaire sampling of opinion in May of 1958.
Incompatibility of Distillate Fuels
Authors: Ward CC , Schwartz FG
Published: March 2009

The current practice of blending straight-run and cracked fuels to supply the expanding market for burner fuels has shown that some blends of fuels are incompatible, which results in troublesome gum deposits. However, few laboratory data were available to show the types of fuel that were incompatible and the degree of incompatibility. A program conducted by the Bureau of Mines, in cooperation with the Western Petroleum Refiners Assn., included several hundred blends of distillate fuels for study of several variables involved in storing blended fuels. Storage of these blends and determination of the amounts of gum formed showed that: 1. Blends may be compatible, incompatible, or supercompatible, 2. The blend of maximum incompatibility depends upon the components of the blend, 3. Blends of straight-run and catalytically cracked fuels show the highest frequency of incompatibility, 4. Solubility is a minor factor in the incompatibility of fuels, and 5. The storage stability of a blend cannot be predicted from the storage stability of its components.
How Accurate is Hand Gaging?
Authors: Peterson CL , Wagner EF
Published: March 2009

Everyone associated with quantity measurement has, at one time or another, asked himself the question, “Just how accurate is hand gaging?” Standard procedures and methods require reading the gage tape to the nearest ⅛ in. and the temperature to the nearest 1 F, but do not mention limits of accuracy. Accuracy is here defined as “freedom from mistake or error” and includes precision. Where do errors occur, what is their magnitude and probable occurrence, and what are the limitations of hand gaging as a standard? To answer these questions, some of the basic considerations in gaging will be reviewed and the results of some test programs the authors have conducted will be examined to determine the accuracy of gaging. Discussion will be limited to the determination of shore tank volumes. Measurement of quantities in marine carriers, tank cars, and tank trucks includes special considerations not involved here. Discussion is further limited to liquid level and temperature associated with bulk volume. Concern will not be given to the problems associated with the determination of gravity or water and sediment, although the calculated net volume of material may also depend on these tests. The results of gaging are influenced by the equipment and methods used and the environment under which the operations are carried out. A quick review of these factors might be helpful.
Suggested Standard Procedures for Use of Positive Displacement Meters in Custody Transfer Measurements
Authors: Wrightsman LS
Published: March 2009

A positive displacement meter is defined as a device installed in a piping system in which flowing liquid is continuously isolated mechanically into segments of known volume. These segments of liquid are counted as they are displaced and their accumulated total is indicated instantaneously in units of liquid quantity by the meter register. These fixed-quantity liquid segments are united as they emerge from the measuring element, along with the portion of liquid that “slips” through the clearances between the moving parts of the measuring element. This slip, which is an inherent characteristic of a positive displacement meter, must be determined and properly accounted for. Positive displacement meters are generally differentiated by the type of mechanism employed to isolate the liquid segments—in other words, by the nature of their measuring elements.
Light Scattering Instrumentation for Particle size Distribution Measurements
Authors: O'Konski CT , Bitron MD , Higuchi WI
Published: March 2009

An improved instrument is described for the characterization of particles suspended in gases by means of light scattering. It consists of (1) a sensitive right-angle optical system with a photomultiplier detector, (2) a coaxial flow system which facilitates variation of the particle concentration range, (3) a photometer which continuously records the average light scattering signal, and (4) a pulse analyzer for size discrimination of individual particles. The particle analyzer was calibrated with uniform polystyrene spheres from a 0.33 to 1.17 μ in diameter, employing air as a scattering standard. The scattering intensity was found to be approximately proportional to the square of the diameter. Resolving power was determined as a function of particle size, and the instrument was critically evaluated. A brief review of particle detectors is given. A versatile pulse height selector system is described. Some variations of the instrument are proposed.
Relative Merits of Gas Chromatography, Colorimetry, and Spectrometry for Air Pollution Studies
Authors: Rogers LH
Published: March 2009

Five instruments useful in air pollution studies have been compared. The two recording colorimeters for oxidant and nitrogen oxides have longer response times than the two spectrometric instruments. The gas Chromatograph is specific for many components, however, it requires a preliminary concentration of the sample. All of the instruments are expensive and some, such as the long-path infrared and gas Chromatograph, require personnel with special training. Nevertheless, these units have proved extremely valuable in understanding the complex chemistry of photochemical smog.
The Operation, Control and Application of the California Design Infrared Weathering Machine
Authors: Skog JB
Published: March 2009

The problem of accelerated weathering of various construction materials is a subject equally important to consumers and producers. Research work has been handicapped by the lack of suitable laboratory equipment to simulate weathering.

The Materials and Research Dept. of the California Division of High-ways has developed a special unit, which employs infrared lamps as the principal agent for inducing change in the test material. This weathering unit is being used in a study of the durability of various types of asphaltic materials, especially the paving grade asphalts.

A description of the equipment and test procedure now in use is given, together with methods for operation. Test data are presented to show the ability of the apparatus to induce identical changes in specimens placed in any position in the machine. A description of the present research program involving the calibration of the unit in terms of field service time for paving grade asphalts is presented, together with a discussion of the difficulties encountered in such a calibration study.
Correlation Between Laboratories on Results of ASTM Tests for Asphalts
Authors: Zube E , Skog JB
Published: March 2009

The accuracy of tests, performed for the purpose of determining compliance with specification requirements, is of primary concern to consumers and producers alike.

The California Division of Highways is the user of approximately 200,000 tons of various asphaltic products per year in the construction and maintenance of its state highways. These products are obtained from about twenty different oil refineries.

During the past ten years the Materials and Research Dept. has conducted, in cooperation with the producer laboratories, four rather extensive test series for the purpose of obtaining information on the precision and reproducibility of the various test methods. Different grades of asphaltic material have been used in the cooperative tests, and all normal specification tests have been included. A statistical analysis of each of the test series is presented, and a comparison is made between values obtained in these studies and ASTM accuracy requirements between laboratories. The Control Chart Method indicates that many laboratories are not within control limits in terms of reproducibility.

A complete study of penetration test results, obtained by sampling the transport truck at the producers loading rack and again at the job site, is also presented. During the past ten years, some 7 to 13 per cent of the job site samples have been found to be “off grade” and out of specification limits when tested for penetration at the Materials and Research Laboratory. The deviation determined from the normal routine testing procedure is considerably greater than that obtained in a carefully controlled cooperative test series.
Factors Affecting the Reproducibility of Oven Heat Tests for Paving Asphalts
Authors: Winniford RS
Published: March 2009

This paper shows how oven design and procedural variations alter the severity of oven heat tests for paving asphalts and thus cause disagreement between laboratories. The tests studied are the ASTM Method D 62 and the thin film oven test.

The paper shows that the reproducibility of the tests can be improved by standardizing such oven design factors as the levelness of the rotating shelves and the rate of air circulation and air transfer in the ovens. Better standardization of procedures also improves reproducibility. The placement of the oven thermometer, the sample size, and the manner of oven operation are shown to affect the severity of the tests. A well-defined procedure for insuring sample uniformity and avoiding penetration changes, except in the actual oven test, may be expected to improve the repeatability of the tests and also the agreement between laboratories. The procedure for obtaining the penetration of test residues can also be profitably standardized.

The thin film oven test is shown to be a more sensitive measure of the changes in weight and penetration occurring in the ovens than is the ASTM Method D 6 for paving asphalts.
Effect of Shape, Size, and Surface Roughness of Aggregate Particles on the Strength of Granular Materials
Authors: Vallerga BA , Seed HB , Monismith CL , Cooper RS
Published: March 2009

The influence of particle shape, size, and surface roughness on the strength of granular materials has been the subject of much discussion in the fields of soil mechanics and asphalt paving technology. A number of investigations have been conducted to determine the effect of variations in particle size and shape, but the results of these investigations have been somewhat varied and have led to conflicting conclusions; and although the effect of surface roughness has been the subject of much discussion, very few data are available to demonstrate its influence.

This paper presents the results of a laboratory investigation to provide further evidence of the influence of these factors in the hope that the results might serve to clarify some of the controversial aspects of their effects.
Cell cycle regulatory control for uterine stromal cell decidualization in implantation
Authors: Das Sanjoy K
Published: March 2009

Uterine stromal cell decidualization is integral to successful embryo implantation, which is a gateway to pregnancy establishment. This process is characterized by stromal cell proliferation and differentiation into decidual cells with polyploidy. The molecular mechanisms that are involved in these events remain poorly understood. The current concept is that locally induced factors with the onset of implantation influence uterine stromal cell proliferation and/or differentiation through modulation of core cell cycle regulators. This review will aim to address the currently available knowledge on interaction between growth factor/homeobox and cell cycle regulatory signaling in the progression of various aspects of decidualization.
Identification of EMS-Induced Mutations inDrosophila melanogasterby Whole-Genome Sequencing
Authors: Blumenstiel Justin P , Noll Aaron C , Griffiths Jennifer A , Perera Anoja G , Walton Kendra N , Gilliland William D , Hawley R Scott , Staehling-Hampton Karen
Published: March 2009

Next-generation methods for rapid whole-genome sequencing enable the identification of single-base-pair mutations in Drosophila by comparing a chromosome bearing a new mutation to the unmutagenized sequence. To validate this approach, we sought to identify the molecular lesion responsible for a recessive EMS-induced mutation affecting egg shell morphology by using Illumina next-generation sequencing. After obtaining sufficient sequence from larvae that were homozygous for either wild-type or mutant chromosomes, we obtained high-quality reads for base pairs composing ∼70% of the third chromosome of both DNA samples. We verified 103 single-base-pair changes between the two chromosomes. Nine changes were nonsynonymous mutations and two were nonsense mutations. One nonsense mutation was in a gene, encore, whose mutations produce an egg shell phenotype also observed in progeny of homozygous mutant mothers. Complementation analysis revealed that the chromosome carried a new functional allele of encore, demonstrating that one round of next-generation sequencing can identify the causative lesion for a phenotype of interest. This new method of whole-genome sequencing represents great promise for mutant mapping in flies, potentially replacing conventional methods.
Detecção do risco para internação hospitalar em população idosa: um estudo a partir da porta de entrada no sistema de saúde suplementar
Authors: Estrella Kylza , Oliveira Claudia E. F. , Sant'Anna Anne A. , Caldas Célia Pereira
Published: March 2009

O envelhecimento populacional impõe a necessidade de criar estratégias de avaliação e acompanhamento para os diferentes grupos da população idosa. O objetivo do artigo é apresentar uma proposta de hierarquização da demanda de idosos em sistema de saúde complementar, com base no uso de instrumento de detecção do risco de internação hospitalar. Esse instrumento foi aplicado por meio telefônico em 2.637 usuários do plano de saúde. A seguir, realizou-se o cálculo do coeficiente de risco de cada idoso, segundo aplicação de regressão logística. A partir dessas respostas calculou-se o índice de probabilidade de admissão hospitalar: 3,23% encontravam-se nos grupos de alto risco; 7,23% de médio-alto, e 13,4% apresentaram médio risco. O modelo permitiu a hierarquização da demanda da população de idosos, de acordo com o risco de internação hospitalar, o que proporcionou melhorar o planejamento e gestão do serviço, pois passou a ser possível dimensionar o quantitativo de indivíduos para intervenção e planejar a assistência. Portanto, estudos que apontem critérios para a distribuição de recursos são cada vez mais imprescindíveis para sustentar políticas de gestão realistas e consistentes.
Condutas de saúde entre universitários: diferenças entre gêneros
Authors: Colares Viviane , Franca Carolina da , Gonzalez Emília
Published: March 2009

Este estudo investigou diferenças entre os gêneros nas condutas de saúde de universitários em final de curso. A amostra foi composta de 382 estudantes de universidades públicas do Estado de Pernambuco, Brasil, com idade entre 20 e 29 anos. Os dados foram coletados mediante a aplicação do questionário National College Health Risk Behavior Survey, validado previamente para o português. Foram utilizadas técnicas de estatística descritiva e inferencial. Para análise de associação foram utilizados teste qui-quadrado ou exato de Fisher. Os resultados foram considerados significantes para p < 0,05. Verificou-se que, de modo geral, os estudantes do gênero feminino apresentaram freqüências menores de condutas de risco para a saúde como: consumo de álcool (p = 0,005), tabagismo (p = 0,002), experimentação de maconha (p = 0,002), consumo de inalantes (p < 0,001), uso de esteróides (p = 0,003), porte de arma (p = 0,001) e envolvimento em briga física (p = 0,014). Os estudantes, no entanto, relataram maior preocupação em perder ou manter o peso, apesar de a prática de atividade física ter sido menos freqüente neste grupo. Pode-se concluir que há diferenças significativas com relação às condutas de saúde entre os gêneros, devendo haver abordagens diferenciadas para os dois grupos.
A population based study on health conditions associated with the use of benzodiazepines among older adults (The Bambuí Health and Aging Study)
Authors: Alvarenga Jussara Mendonça , Loyola Filho Antônio Ignácio de , Firmo Josélia Oliveira Araújo , Lima-Costa Maria Fernanda , Uchoa Elizabeth
Published: March 2009

The aim of this study was to assess the health conditions and use of health services among elderly users of benzodiazepines. The study was carried out in the city of Bambuí in Minas Gerais State, Brazil. Of 1,742 inhabitants aged over 60, 1,419 participated in the study. Information about benzodiazepine and the use of other medications was obtained by means of interviews and checking medication packaging. After adjustments for confounding variables, benzodiazepine remained significantly associated with poorer self reported health (prevalence ratio = 1.94 and 2.04 for reasonable and bad/very bad health, respectively), common mental disorders (1.33), myocardial infarction (1.42), number of doctor visits in the previous 12 months (1.90 and 2.24 for 2-3 and 4+ visits, respectively) and concomitant use of other medications (1.84 and 1.83 for 2-4 and 5+ medications). The results showed that the factors associated with the use of benzodiazepine were similar to those observed in the elderly in higher income countries. The concomitant use of benzodiazepines and two or more medications was highly prevalent (59.5%), characterizing a situation of risk, which deserves attention as a public health problem.
Conhecimento objetivo e percebido sobre contraceptivos hormonais orais entre adolescentes com antecedentes gestacionais
Authors: Sousa Michelle Chintia Rodrigues de , Gomes Keila Rejane Oliveira
Published: March 2009

A elevada freqüência de gestação precoce no Brasil e, particularmente, em Teresina (21,5%), Piauí, motivou o presente estudo, cuja meta foi identificar os níveis de conhecimento objetivo e percebido sobre contraceptivos hormonais orais, bem como variáveis reprodutivas e sócio-demográficas preditoras de elevado conhecimento. Realizou-se estudo transversal com 278 adolescentes com idade de 15 a 19 anos de idade, com antecedentes reprodutivos, internadas em quatro maternidades de Teresina, em 2006. Regressão logística foi a base da análise estatística. Quase 98% das adolescentes apresentaram baixo conhecimento tanto objetivo quanto percebido. Apenas o maior número de gestações foi preditor de elevado conhecimento objetivo para anticoncepcionais orais. Os baixos níveis de conhecimento objetivo e percebido das adolescentes sobre o uso de anticoncepcionais orais revelam a suscetibilidade das jovens ao comportamento sexual de risco. Sugere-se a utilização de abordagem mais interativa com os adolescentes para elevar o nível de conhecimento tanto objetivo quanto percebido deles, e assim reduzir a incidência e reincidência da gravidez indesejada na adolescência e suas conseqüências negativas na vida destas jovens e de sua prole.
Fatores associados a hábitos de saúde bucal e utilização de serviços odontológicos entre adolescentes
Authors: Davoglio Rosane Silvia , Aerts Denise Rangel Ganzo de Castro , Abegg Claídes , Freddo Silvia Letícia , Monteiro Lisiane
Published: March 2009

Estudo transversal com 1.170 adolescentes da sétima série da rede pública municipal de Gravataí, Rio Grande do Sul, Brasil, investigando a associação de fatores sócio-demográficos, psicossociais e relacionados ao estilo de vida com hábitos de saúde bucal e utilização de serviços odontológicos. Os dados foram analisados por regressão de Cox modificada para estudos transversais. As meninas tiveram maior freqüência de escovação dentária assim como aqueles que relataram não se sentirem discriminados ou sozinhos. O uso diário de fio dental associou-se à melhor inserção sócio-econômica, à busca por serviços privados, à compreensão dos pais e à ausência de sentimento de solidão. A freqüência anual de utilização de serviços odontológicos foi maior entre os de inserção sócio-econômica mais alta. Houve maior busca de serviços por motivo preventivo entre aqueles com melhor inserção sócio-econômica, os que se sentiram compreendidos pelos pais e os que não costumavam consumir doces. Os hábitos de saúde bucal apresentaram associação com inserção sócio-econômica familiar e com fatores psicossociais, exceção à utilização anual de serviços. Quanto ao estilo de vida, o baixo consumo de doces repercutiu positivamente sobre o motivo da visita ao serviço.
Prevalence and risk factors for HIV, syphilis, hepatitis B, hepatitis C, and HTLV-I/II infection in low-income postpartum and pregnant women in Greater Metropolitan Vitória, Espírito Santo State, Brazil
Authors: Lima Lucia Helena Mello de , Viana Maria Carmen
Published: March 2009

Sexually transmitted infections during pregnancy pose a major risk to the fetus due to vertical transmission. The study's objective was to determine the prevalence of HIV, syphilis, hepatitis B and C, and HTLV-I/II infection among low-income postpartum and pregnant women treated in Greater Metropolitan Vitória, Espírito Santo State, Brazil, and the risk factors associated with these infections. A cross-sectional study was conducted from February to October 1999 assessing postpartum and pregnant women from the maternity ward of the Vitória Mercy Hospital and the Carapina Outpatient Referral Unit in the Municipality of Serra, respectively. Patients were systematically interviewed and had blood samples drawn for serological tests (HIV 1&2, VDRL, HbsAg, anti-HCV, and HTLV-I/II). A total of 534 patients (332 postpartum and 202 pregnant women) were assessed. Seroprevalence rates for the target infections in postpartum and pregnant women and the overall sample were as follows, respectively: HIV 0.9%, 0%, and 0.6%; syphilis 2.1%, 3.6%, and 2.7%; HBV 1.2%, 1%, and 1.1%; HCV 1.8%, 0.6%, and 1.4%; and HTLV-I/II 1.7%, 0.6%, and 1.3%. Factors associated with the various infections are presented and analyzed in light of other research findings from the literature.
Eventos estressores em crianças e adolescentes em situação de vulnerabilidade social de Porto Alegre
Authors: Poletto Michele , Koller Sílvia Helena , Dell'Aglio Débora Dalbosco
Published: March 2009

O presente artigo investigou a ocorrência e o impacto de eventos estressores para 297 crianças/adolescentes em situação de vulnerabilidade social de Porto Alegre (ambos os sexos; 7-16 anos, M = 11,22; SD = 2,13). O grupo 1 (G1) consistiu em 142 participantes, que viviam com suas famílias e o grupo 2 (G2), em 155 institucionalizados. Todos foram entrevistados e responderam individualmente ao Inventário de Eventos Estressores na Infância/Adolescência. Os eventos estressores mais freqüentes para amostra total foram: cumprir ordens dos pais (85,2%); discussão com amigos (72,9%); morte de familiares (71,8%); reprovação escolar (69,2%); e brigas com irmãos (68%). Um teste t de Student revelou diferença significativa entre G1 e G2 (p< 0,001) na variável ocorrência de eventos estressores, sendo que G2 apresentou médias mais altas (M = 26,79; SD = 8,67) que G1 (M = 19,16; SD = 9,37). Os eventos que tiveram maior impacto na amostra estudada foram: morte dos pais e amigos, estupro, rejeição de familiares e sofrer violência. Não houve diferença significativa entre meninos e meninas (p>0,05). A alta ocorrência e impacto de eventos estressores expõem a situação de vulnerabilidade social e familiar, presença de violência e privação de recursos em ambos os grupos.
Crianças e adolescentes em situação de rua: contribuições para a compreensão dos processos de vulnerabilidade e desfiliação social
Authors: Gontijo Daniela Tavares , Medeiros Marcelo
Published: March 2009

O conceito de vulnerabilidade vem sendo discutido no campo da saúde coletiva como um potencial instrumento para transformação nas práticas de saúde, uma vez que possibilita uma articulação entre indivíduo-coletivo. Entendendo a saúde como um processo de subjetivação determinada por contextos sociais, culturais e históricos, o presente artigo pretende abordar o tema crianças e adolescentes em situação de rua, a partir do conceito de vulnerabilidade, com base nas lentes teóricas apresentadas por Robert Castel. Castel entende a situação de marginalidade vivenciada por diferentes indivíduos e grupos sociais de forma dinâmica, através dos eixos do trabalho e da inserção relacional. No que se refere às crianças e adolescentes em situação de rua, acreditamos que elas refletem um processo de intensificação da vulnerabilidade (que culmina na desfiliação) a que estão submetidas milhares de famílias brasileiras, em virtude do quadro de extrema desigualdade social vivenciado em nosso país. Esperamos que nossas reflexões contribuam para a construção de um referencial teórico em saúde coletiva que forneça subsídios para o planejamento e implementação de ações de saúde direcionadas a esta população.
UK microgeneration. Part I: policy and behavioural aspects
Authors: Bergman N. , Hawkes A. , Brett D. J. L. , Baker P. , Barton J. , Blanchard R. , Brandon N. P. , Infield D. , Jardine C. , Kelly N. , Leach M. , Matian M. , Peacock A. D. , Staffell I. , Sudtharalingam S. , Woodman B.
Published: March 2009

A critical review of the literature relating to government policy and behavioural aspects relevant to the uptake and application of microgeneration in the UK is presented. Given the current policy context aspiring to zero-carbon new homes by 2016 and a variety of minimum standards and financial policy instruments supporting microgeneration in existing dwellings, it appears that this class of technologies could make a significant contribution to UK energy supply and low-carbon buildings in the future. Indeed, achievement of a reduction in greenhouse gas emissions by 80% (the UK government’s 2050 target) for the residential sector may entail substantial deployment of microgeneration. Realisation of the large potential market for microgeneration relies on a variety of interrelated factors such as microeconomics, behavioural aspects, the structure of supporting policy instruments and well-informed technology development. This paper explores these issues in terms of current and proposed policy instruments in the UK. Behavioural aspects associated with both initial uptake of the technology and after purchase are also considered.
Predicted temperatures and service lives of secondary geomembrane landfill liners
Authors: Rowe R. K. , Hoor A.
Published: March 2009

The heat flow through double composite landfill liner systems is modelled for different liner configurations and different modes of landfill operation. The estimated temperature is used to estimate the likely service life (SL) of the secondary geomembrane (SGM) and to compare this with the SL of the primary geomembrane (PGM). The results show that the temperature in SGM is high enough to impact on its SL, and this should be considered in the design of landfill liners. The SL of the SGM was a minimum for an all-geosynthetic system, ranging between 310 years if the PGM temperature is at or below 30°C and 50 years when the PGM is at 50°C. This SL could be improved to between 390 years at 30°C and 75 years at 50°C by the use of a primary composite liner involving a GM and either a GCL and a 1 m thick foundation layer or a 1 m thick CCL. These predictions assume that the temperature of the primary liner remains constant over the period of time being considered. Consideration of a temperature–time history will give longer estimates of service life for a given peak liner temperature. Nevertheless, this study suggests that the temperature of the secondary liner requires consideration in the design of MSW landfills to ensure that the SL of the system is likely to exceed the contaminating lifespan for a particular design.
Effect of polymer conditioning on dewatering characteristics of fine sediment slurry using geotextiles
Authors: Satyamurthy R. , Bhatia S. K.
Published: March 2009

Results from laboratory investigations for evaluation and enhancement of the dewatering performance of fine silt slurry are presented. These experiments were conducted with and without polymer conditioning of the slurry. One type of soil and five types of geotextile were used. The optimal dewatering conditions were investigated using one woven geotextile. An innovative methodology is proposed for determining optimal dewatering considerations using a combination of simple bench-scale tests (jar sedimentation test, jar test, and pressure filtration test). The current state of practice utilises a trial-and-error approach heavily dependent on operator judgement, and ignores the role of the geotextile and the simulation of field mixing conditions. The proposed methodology provides a rational method to determine the optimal dewatering conditions in terms of dewatering time and amount of piping under anticipated field conditions. This novel approach guides the selection and evaluation of candidate polymers, which can be further evaluated in greater detail using pilot-scale tests. It is demonstrated that considerable enhancement can be achieved in the dewatering performance through polymer conditioning. Based on the results of this investigation, it is demonstrated that optimal dewatering conditions (maximum filtration efficiency and minimum dewatering time) can be arrived at with the methods proposed here.
Ten-year PVC geomembrane durability
Authors: Newman E. J. , Stark T. D.
Published: March 2009

The 10-year results of an ongoing study on the long-term performance of a PVC geomembrane in northern Minnesota are presented. Samples of PVC geomembrane and seams are exhumed periodically over a 30-year period and tested to measure the certified, index, and seam properties of the exhumed geomembrane and seams. Results are compared with the material specification existing at the time of installation as well as with the current PVC geomembrane specification prepared by the PVC Geomembrane Institute. All material properties except for thickness meet both specifications. Material properties measured at the laboratory and field moisture conditions are compared, and indicate that testing at the field moisture condition is more representative of the field performance than after laboratory desiccation. Data measured over a ten-year period suggest that the in situ moisture condition may counteract some, if not all, of the plasticizer migration that occurs in this application, and plasticizer migration slows as the geomembrane becomes acclimated to the field environment.
Is Reverse Osmosis Effective for Produced Water Purification: Viability and Economic Analysis
Authors: Muraleedaaran Shanker , Li Xinhua , Li Liangxiong , Lee Robert
Published: March 2009

The ultimate goal of produced water management is to remove dissolved components and use the desalinated water for beneficial uses that can effectively alleviate environmental impact and water shortage. Presently, many of the efforts have been focused on membrane technologies including reverse osmosis and electrodialysis. Unfortunately, no large scale implication of produced water desalination by membranes has been reported. The main obstacle against the deployment of desalination technologies for produced water purification has always been the complicated chemical composition and associated high operating cost. Membrane technologies are generally believed to be energy efficient due to single-phase operation comparing to thermal-based desalinations. However, the presence of dissolved organics and scale deposition on membrane surfaces require sophisticated pretreatment and frequent membrane replacement, adding to the water treatment costs.

Reverse osmosis membranes including polymeric membranes and molecular sieve zeolite membranes were investigated for ion removal from produced water by a cross-flow RO process. Considerable flux decline with elapsed operation time was observed from 11.5 to 6.8 L/m2.h at a transmembrane pressure of 3.5 Mpa. Pretreatments including nanofiltration and adsorption by active carbon were studied for their influence on the RO performance and impact on the overall desalination cost. Both polymeric membranes and molecular sieve zeolite membranes have been tested for actual produced water from oilfield and coalbed methane site. The study has revealed that (1) most of permeation tests lasted less than 3 months due to serious fouling and drastic flux decline (>30%), (2) scale precipitation and organic sorption are the major fouling mechanisms of membranes, (2) multistage pretreatment is crucial to extend membrane lifetime, and (3) nanofiltration is the only effective process tested that can extend the life of a RO membrane to over 6 months. But periodic chemical cleaning, typically twice a week, is necessary to maintain the desired water flux. The economical efficiency of these processes was discussed from the aspects of produced water chemistry, energy consumption, and water treatment capacity. Considering small to mid-sized water treatment capacity (50 m3/day), the cost of produced water desalination by RO membranes is around $3.7/m3 including nanofiltration pretreatment. Pretreatment and membrane replacement are the major factors that increases the operation cost and limits the economic efficiency of membrane technology for produced water desalination.
Optimum Tertiary Steam-Injection Strategies for Oil-Wet Fractured Carbonates
Authors: Akin Serhat , Celebioglu Demet , Kalfa Ulker
Published: March 2009

Steam injection in naturally fractured formations has drawn considerable interest recently. It is believed that the steam or water heats the rock, which then undergoes a thermally induced wettability reversal. Hot water can then spontaneously imbibe into the water wet rock matrix, resulting in favorable oil recoveries. In this study, the applicability of steam injection in an oil wet fractured carbonate previously flooded with carbon dioxide (CO2) through multi-component thermal simulations is discussed. A numerical sector model calibrated with 47 years of historical data and data from vintage pre 1970's steam pilot carried out in south east Turkey was used to study optimum operating conditions such as continuous steam injection, cyclic steam injection, steam alternating CO2 injection (SAC) and steam injection with additives such as naphta and CO2. It was observed that for both operating strategies key oil production mechanism is heat transport through the fractures and the matrix suggesting that the success of the process is directly related with fracture spacing and fracture-matrix transfer. Sensitivity studies carried out for differing fracture densities indicated a threshold fracture spacing (7 ft matrix blocks) below which process efficiency significantly decreased. It was further observed that addition of limited amounts of naphta to steam may improve the process; however, CO2 presence adversely affects the heat transport such that too much CO2 limits the heat transfer along the fractures.
Well Placement in a Mature California Field
Authors: Okafor Z. M. , Moore E. E.
Published: March 2009

In mature fields, accurate well placement is critical in avoiding collisions with existing wells. This paper reviews the procedures developed to help avoid well collisions in the Wilmington Townlot Unit in Long Beach, California.

The field has over 2,500 existing wells. The spacing of the wells is managed to avoid well collisions and prevent making future slots unusable. These considerations lead to complexities in well design and execution. To limit the risk of incidents that can lead to personal injury, environmental damage, and significant financial loss, specific procedures were developed for well planning and execution. This paper presents the results from multiple wells managed by this process. The risk assessment approach and the team work between the operator and the directional drilling services company produces consistently good results in managing the well collision risks associated with drilling these difficult wells.
Thaw Front Dynamics and Super Insulated Well for Thermal Recovery in Cold Environments
Authors: Marques C. , Castanier L. M. , Kovscek A. R.
Published: March 2009

Thermal recovery methods such as steam injection or in-situ combustion are preferred for heavy oil. In cold environments, wellbore heat losses are significant and limit the applicability of thermal recovery. Therefore, it is essential to insulate the well effectively and economically.

Our study focuses primarily on the problem of wells penetrating thick layers of frozen earth (i.e., permafrost). The experimental component determines thermal conductivity versus temperature of nanomaterials fashioned into insulation (socalled black and white silica aerogels that are 90-99.8% air), fiberglass, thermolastic insulation, and carbon fibers. A comparator thermal conductivity apparatus as well as direct measurements using heat flux sensors were developed. A simplistic experimental simulation explored the role of mechanical stress due to thermal cycling.

Semianalytical and numerical models were also developed to design a superinsulated well. The models incorporate various composite insulations. Computations include wellbore heat losses, wellbore temperature and the permafrost temperature. Different processes were simulated including an injector well with constant fluid temperature. Well failure/stability is inferred from the rate of thaw front propagation. A key parameter is the insulation thermal conductivity versus temperature that is measured directly.

Results show agreement of conductivity with literature values at ambient temperature. Aerogels (0.012-0.025 W/m K) are half as conductive as fiberglass (0.03-0.045 W/m K) and three to four times less conductive than thermolastic insulation and carbon fibers (0.04-0.067 W/m K) for temperatures between 40 and 140 °C. Moreover, aerogels and carbon fibers have good mechanical resistance in comparison to fiberglass. The wellbore heat loss and thaw front propagation model indicates that aerogels alone or aerogels in a composite with more conductive insulation may meet the requirements to avoid well failure, even for very high temperature fluids and over long periods.

Thus, alone or in combination with active subcooling of the permafrost, aerogel insulations appear to provide effective thermal isolation to insure well integrity. Although aerogel insulations alone are not as effective as active refrigeration, their moderate cost and their ease of use encourage further investigation.
An Improved Approach for Ensemble-Based Production Optimization
Authors: Chaudhri Masroor M. , Phale Hemant A. , Liu Ning , Oliver Dean S.
Published: March 2009

For oil reservoirs under water and/or gas drive, it is challenging and rewarding to effectively manage the water/gas fronts to maximize the sweep efficiency. In the past, a wide variety of approaches were developed and implemented for optimizing the reservoir performance by smartly adjusting operational controls. With recent developments in monitoring and control, the opportunity to optimize reservoir production through frequent adjustment of well controls has substantially increased. In this paper, we propose an improved ensemble-based approach for production optimization using Conjugate Gradient method (CGEnOpt). The proposed method results in faster convergence rate as a result of using the conjugate gradient directions instead of steepest ascent search directions. The net present value (NPV) of a single reservoir is optimized by obtaining the gradient of the NPV from an ensemble of control variables.

The effectiveness of the proposed method is demonstrated on a 3-D synthetic reservoir problem with 8 producers and 3 injectors. The production and injection rates are used as control variables to maximize NPV of the reservoir.

The results indicate that the control settings from the proposed method result in a significantly higher NPV of the reservoir as compared to the reference case. The number of iterations needed for the proposed method is significantly reduced compared to the standard ensemble-based optimization. The proposed method is able to allocate the production and injection rates effectively which results in a substantial decrease in the amount of water produced.

The proposed method is completely adjoint-free and is independent of the reservoir simulator used for the prediction simulation run which makes it fairly robust. Thus, it can be used with any existing simulator with minimal code development. The CGEnOpt technique is innovative for not requiring explicit computation of the gradient which makes it easy to implement.
Development and Application of a Fully-Coupled Thermal Compositional Wellbore Flow Model
Authors: Livescu S. , Aziz K. , Durlofsky L. J.
Published: March 2009

Thermal recovery processes are widely used for heavy oil production and are under investigation for other unconventional resources. The management and optimization of these processes require accurate representations of relevant physical phenomena in simulation models. An important aspect of the simulation capability is the modeling of flow in the wellbore and the coupling of wellbore and reservoir flows. In previous work, we developed and applied a black-oil thermal multiphase wellbore model and linked it to Stanford's General Purpose Research Simulator (GPRS). In this paper, we extend this formulation to treat thermal compositional systems. GPRS already contains a thermal compositional capability for reservoir flow; here we develop and test a thermal compositional wellbore model. This wellbore model includes an energy conservation equation, mass conservation equations for each component, and a general pressure drop relationship. The multiphase wellbore flow is represented using a drift-flux model, which includes slip between the three phases. The model determines the temperature, pressure, mixture flow velocity and component fractions as functions of time and axial position along the well. We apply the coupled thermal compositional wellbore-reservoir model to the simulation of several cases involving thermal effects. These include a verification example, in which we compare results from the compositional formulation to those of a black-oil model, and an example with seven components. Different well geometries (e.g., dual-lateral and deviated with varying inclination angle) are considered in these applications.
A Novel Method for Mapping Fractures and High Permeability Channels in Waterfloods Using Injection and Production Rates
Authors: Lee Kun-Han , Ortega Antonio , Nejad Amir Mohammad , Jafroodi Nelia , Ershaghi Iraj
Published: March 2009

This paper extends the work reported in SPE114222 for managing waterfloods using estimation of flow characteristics from only injection and production rates. The method first estimates the finite impulse response (FIR) curve corresponding to the fluid-flow between all injector-producer pairs. This FIR curve is analogous to the pressure curves obtained from pulse testing. Reservoir parameters, such as connectivity between wells, can be estimated from this curve, which can also be used to characterize variations of relative flow as a function of storage capacity (F-C plots), thus making it possible to quantify the heterogeneity of flow paths between wells.

Our proposed method is capable of identifying the flow channel relationships between all injector-producer well pairs. This helps in reservoir characterization, where information provided by the proposed procedure can describe the characteristics of flow-path between injector-producer pairs. It can also help in waterflood optimization by tracking sweep efficiency and balancing voidage-replacement. The method has been successfully tested and calibrated for simulated line drive patterns with various fracture geometry conditions. It successfully quantifies the interwell connectivity and the heterogeneous properties in the numerical simulations.

Our procedure has several advantages over pulse testing and tracer tests. In comparison to pulse testing, pressure data is not required and the only data needed are injection/production rates, which are often routinely available with high temporal resolution for many reservoirs. The quality of measured production rates affects the estimated properties. Because the proposed procedure can be routinely performed and implemented, the proposed procedure leads to a dynamic approach for reservoir and fluid flow mapping, where the results can be refined over time. Additionally, our procedure could also be used for better designs of pulse or tracer tests. Finally, once the flow channels are mapped, one can balance the flood and make diagnostic predictions about future response under any given injector scenarios.
Implementation of Efficient Plant Designs in a Time Constrained Market
Authors: Hoyer D. , Gray T.
Published: March 2009

This paper compares different energy conversion rates for some geothermal power plant cycles. These are being implemented at two high temperature, liquid dominated reservoirs; Kawerau and Rotokawa.

The power plant cycle selected for the first development is a dual flash, condensing steam turbine; however, optimisation with higher pressures and enthalpies resulted in a triple flash, condensing steam turbine for the second development. This will be the largest single cylinder geothermal steam turbine in the world. The project is currently under construction with commercial operation scheduled for the first half of 2010.

The environmental consent process in New Zealand provides a fixed average fluid extraction rate and an instantaneous maximum. Geothermal fluid conditions, (including; enthalpy, non-condensable gas content and chemistry) were defined from well test results and reservoir modelling. The owners’ financial model has been used to provide key metrics for selection of the plant cycle giving the maximum revenue from the consented geothermal fluid flow, considering life cycle costs. In one example, a triple flash cycle developed 6MW more than the comparable dual flash cycle, for which the economic benefit exceeded the additional capital and life cycle cost. Alternatives using multiple turbines were considered and interesting options developed. A risk review was completed to evaluate operating experience of similar equipment and design features.