bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rotor Current Control of DFIG for Improving Fault Ride – Through Using a Novel Sliding Mode Control Approach
Authors: Cai Guowei , Liu Cheng , Yang Deyou 
Published: November 2013

AbstractThe doubly fed induction generators (DFIG) have been recognized as the dominant technology used in wind power generation systems with the rapid development of wind power. However, continuous operation of DFIG may cause a serious wind turbine generators tripping accident, due to destructive over-current in the rotor winding which is caused by the power system fault or inefficient fault ride-through (FRT) strategy. A new rotor current control scheme in the rotor-side converter (RSC) ispresented to enhance FRT capacities of grid-connected DFIG. Due to the strongly nonlinear nature of DFIG and insensitive to DFIG parameter’s variations, a novel sliding mode controller was designed. The controller combines extended state observer (ESO) with sliding model variable structure control theory. The simulation is carried out to verify the effectiveness of the proposed control approach under various types of grid disturbances. It is shown that the proposed controller provides enhanced transient features than the classic proportional-integral control. The proposed control method can effectively reduce over-current in the RSC, and the transient pulse value of electromagnetic torque is too large under power grid fault.
Evaluation of the role of first-trimester obstetric ultrasound in the detection of major anomalies: a systematic review
Authors: Farraposo Sílvia , Montenegro Nuno , Matias Alexandra 
Published: November 2013

Abstract

Aim: To perform a systematic review to assess the accuracy of first-trimester ultrasound (US) in the diagnoses of major structural malformations in chromosomally normal fetuses.

Methods: References were obtained from the MEDLINE database, without time range limitations. For each, the risk of bias was evaluated and the important data were extracted. Only studies that used first-trimester US to diagnose major structural malformations were included. We evaluated the sensitivity of US over a low-risk unselected population of pregnant women carrying euploid fetuses.

Results: A total of 19 studies were included, contributing to 126,937 fetuses and 1399 major malformations. The prevalence of lethal and severe malformations obtained was 1.2% [95% confidence interval (CI), 1.0–1.4]. Both averaged and pooled sensitivity, 50.0% (95% CI 44.1–55.9) and 45.2%, respectively, presented a moderate value for first-trimester US in the detection of structural malformations.

Conclusion: Based on our analysis of the data, the average sensitivity of first-trimester US to detect structural malformations was 50%. It is our conviction that US has the potential to evolve in this role by exploiting the natural history of malformations and the development of US techniques.
Educating Culturally Diverse Students with Challenging Behaviors: A Review of Literature
Authors: Carrero Kelly M. , Lusk Mandy E. 
Published: November 2013

Abstract
Changing demographics in American school systems necessitate educators to better prepare themselves to work with students from diverse backgrounds. Moreover, culturally diverse (CD) students are disproportionately represented in special education, indicating a need to investigate assessment for identification purposes. We, the authors, believe that examining current research in higher education will highlight the need for effective special education teachers prepared to teach CD learners with challenging behaviors. This article is a review of existing literature related to educating CD students with challenging behaviors and preparing special education teacher candidates for this population.
Macro-Scale Direct Shear Test Device for Assessing Soil-Solid Interface Friction Under Low Effective Normal Stresses
Authors: Wijewickreme Dharma , Amarasinghe Ruslan , Eid Hisham 
Published: November 2013

Abstract
The paper describes a new macro-scale direct shear test device for assessing the large-displacement soil/solid interface drained shear strength at low effective normal stresses. The testing method arises from a need to obtain the interface friction between soils and pipelines under low effective normal stress levels, which is an important consideration in the design of pipelines laid on the sea bed. The test device is fundamentally similar to the conventional small-scale direct shear box device except for its large footprint that provides a plan interface shear area of 3 m2 (1.72 m by 1.75 m). The device is designed to impart displacement-controlled interface-shearing at displacement rates ranging from 0.0001 mm/s to 1 mm/s and with the ability to reach a maximum interface shear displacement of 1.2 m. The desired normal stress at the soil/solid interface is obtained using surcharge loads externally applied by means of bulk sand or water masses, or both in certain cases. The device is instrumented with transducers mounted flush with the top of the solid surface for the measurement of pore-water pressure at the shear interface. As a result, the device allows for accurate determination of the effective normal stress at the soil/solid interface during interface shear testing. The key features of this device are described, and the device capabilities are demonstrated using tests conducted on Fraser-River-sand/mild-steel, plastic-silt/epoxy-coated-mild-steel, non-plastic-silt/epoxy-coated-mild-steel, and kaolinite/epoxy-coated-mild-steel interfaces at effective normal stresses between 3 and 7 kPa. The results can be also used as benchmarks to justify possible modifications of the currently available small-scale apparatus to reliably measure interface shear strength at such low effective normal stresses.
The Use of SNP Markers for Linkage Mapping in Diploid and Tetraploid Peanuts
Authors: Bertioli David J , Ozias-Akins Peggy , Chu Ye , Dantas Karinne M , Santos Silvio P , Gouvea Ediene , Guimarães Patricia M , Leal-Bertioli Soraya C M , Knapp Steven J , Moretzsohn Marcio C 
Published: November 2013

AbstractSingle nucleotide polymorphic markers (SNPs) are attractive for use in genetic mapping and marker-assisted breeding because they can be scored in parallel assays at favorable costs. However, scoring SNP markers in polyploid plants like the peanut is problematic because of interfering signal generated from the DNA bases that are homeologous to those being assayed. The present study used a previously constructed 1536 GoldenGate SNP assay developed using SNPs identified between two A. duranensis accessions. In this study, the performance of this assay was tested on two RIL mapping populations, one diploid (A. duranensis × A. stenosperma) and one tetraploid [A. hypogaea cv. Runner IAC 886 × synthetic tetraploid (A. ipaënsis × A. duranensis)4×]. The scoring was performed using the software GenomeStudio version 2011.1. For the diploid, polymorphic markers provided excellent genotyping scores with default software parameters. In the tetraploid, as expected, most of the polymorphic markers provided signal intensity plots that were distorted compared to diploid patterns and that were incorrectly scored using default parameters. However, these scorings were easily corrected using the GenomeStudio software. The degree of distortion was highly variable. Of the polymorphic markers, approximately 10% showed no distortion at all behaving as expected for single-dose markers, and another 30% showed low distortion and could be considered high-quality. The genotyped markers were incorporated into diploid and tetraploid genetic maps of Arachis and, in the latter case, were located almost entirely on A genome linkage groups.
Dimensional Changes During Early Healing After a Subepithelial Connective Tissue Graft Procedure
Authors: Rotenberg Shaun A. , Tatakis Dimitris N. 
Published: November 2013

Background: The subepithelial connective tissue graft (CTG) is a popular means to treat gingival recession and augment keratinized tissue. Studies exist that examine long‐term outcomes of this procedure; however, changes in tissue dimensions during early healing (0 to 21 days postoperatively) are unknown. The aim of this study is to examine bucco‐lingual tissue dimension (gingival tissue thickness [GT]) changes during early CTG healing using a non‐invasive technique.Methods: Thirteen patients who had treatment planned for CTG on a single tooth were recruited for the study. Using a customized acrylic stent, GT was measured preoperatively, at surgery completion, and at 3, 7, 14, and 21 days postoperatively. CTG was performed using an envelope technique. GT changes were analyzed by repeated‐measures analysis of variance.Results: All CTG procedures were considered successful with no postoperative complications. GT increased 1.5 mm immediately after surgery (baseline) compared to the preoperative measurement. GT increased on average 96%, 47%, and 2% compared to baseline at days 3, 7, and 14, respectively. Day 3 and day 7 measurements were significantly different from baseline (P <0.001). At day 21, GT decreased 15% compared to baseline, with an average increase of 1.29 mm from preoperative measurements.Conclusions: The early postoperative healing of CTGs used for root coverage exhibits a significant but transient increase in bucco‐lingual tissue dimension. The observed increase in bucco‐lingual tissue dimension subsides by the end of the second postoperative week.
Novel Steam-Resilient Cement System for Long-Term Steam Injection Well Integrity: Case Study of a Steamflooded Field in Indonesia
Authors: Salehpour A. G. , Pershikova E.. , Chougnet-Sirapian A.. , Taoutaou S.. , Adiningtyas D. A. 
Published: November 2013

Abstract
A major challenge of a steamflooded field in Indonesia, one of the world's largest thermal recovery projects, is the short life of the well from the well integrity aspect. The outcome of a joint study group between the operator and the cementing service provider reveals that 77% of the injector wells drilled in a recent period of 5 years required remedial squeeze cementing operations. The operating expenditure of workover operations and the costs of the deferred production to the operator are significant; hence, a cementing solution is needed to improve the efficiency in managing the mature heavy oil reserve.
The current cementing practice calls for placing the API class G cement and silica flour blended system across unconsolidated sand bodies and exposing it to large temperature changes. Results of the stress modeling predict the conventional cement system failure under the anticipated conditions of injection and workover operations. An innovative steam-resilient cement system with tailored thermal and mechanical properties up to a temperature of at least 350° C [650° F], beyond the maximum steam injection temperature of the field, is maintaining the integrity.
Field trials in Indonesia confirm that this new system can be easily integrated into standard cementing operations using conventional equipment. Cement evaluation logs after cement operations prove that proper zonal isolation is achieved. All the candidate wells, first one since January 2011, are currently under the steam injection with no sign of wellbore integrity failure.
This novel cement system, by keeping adequate level of flexibility and optimum thermal properties, provides a long term well integrity solution for any well exposed to similar conditions, such as in fields exposed to steam injection. Operators can rely on cement sheath integrity exposed to thermal processes to produce heavy oils.
Fiscal Regimes: It's not just costs that drive LNG prices
Authors: Gurney David 
Published: November 2013

Abstract
There is much talk and speculation around the impact of the next wave of LNG due to come onto the market from the US driven by the shale oil/gas revolution over the last few years.
This paper examines the competitive position of several alternative sources of LNG relative to the US LNG exports into the North Asian market. Specifically the Area 1 and Area 4 Mozambique LNG scheme and three generic Australian schemes: a conventional deepwater gas source, a coal seam gas source and a prospective shale/tight gas supply. The paper also looks at the fiscal position of each of these non-US projects to examine the impact on the delivered price of LNG.
End buyers argue that US sourced LNG delivered ex-ship to North Asia will be less than $11/MMBtu. If these prices are realised, the integrated projects making up the non-US suppliers will struggle to compete for the current round of LNG contracts. However, the volume of US LNG is expected to be limited to 40–50 MMtpa of supply (including currently approved projects). Once this US LNG is contracted, pressure for lower prices or alternative pricing mechanisms should ease as new demand is sourced from higher cost locations. For projects looking to be competitive marketing LNG into North Asia for initial delivery this decade, it seems that the US ‘benchmark’ may prevail.
The $11/MMBtu delivered price is predicated on a sub $4/MMBtu feedstock gas price. If and when US gas prices rise above $5/MMBtu and provided LNG carrier rates do not collapse, the longer-term delivered price for US gas will not be materially below the equivalent price for ‘conventionally priced’ oil-indexed LNG from integrated non-US supplies into North Asia. Also, existing oil indexation formulae will be competitive to US supplies if the oil price slips to around $80/bbl.
The paper demonstrates that Australian deepwater conventional gas to LNG supply will be competitive to Mozambique's deepwater supplies. This is partly attributable to the higher liquids content in much Australian gas than in the Mozambique gas and to the harsher fiscal terms that apply to the Mozambique upstream investment; the Government take is over fifty percent higher than for a similar Australian project. Australian LNG from unconventional gas sources is predicted to struggle against the low unit cost Mozambique supplies even with a total tax burden of only one third of the Mozambique levels.
Fracture Design Optimization of Horizontal Wells Targeting the Chang 6 Formation in the Huaqing Oilfield
Authors: Qi Yin , Wu Zongfu , Bai Xiaohu , Li Chuan , Chang Du , Ji Zhenning , Lu Ling , Wang Jianhui , Duan Penghui 
Published: November 2013

Abstract
Huge oil reserves are located in ultra-low permeability reservoirs in the Ordos basin in China. There are three key characteristics associated with these reservoirs: low reservoir quality (10 to 13% in porosity), low reservoir permeability (0.3 to 2.0 mD), and low reservoir pressures (pressure gradients of 0.0075 to 0.009 MPa/m). The Chang 6 formation in the Huaqing field is classified as ultra-low permeability reservoirs. Water injection to maintain reservoir pressure is important to develop the Chang 6 formation in horizontal wells. Fracturing design optimization is the key to improving well production and reservoir development effectiveness. Reservoir simulation studies were performed to determine optimal well pattern and well spacing. Fracture modeling studies were also conducted to determine the optimal number of fracture stages in each horizontal well and to optimize fracture design for each stage in order to take into consideration the relative location between each individual stage and nearby injection wells, with the objective of postponing water breakthrough and reducing water production. Completion, stimulation and cumulative production data from 24 horizontal wells were compiled and compared with 121 vertical wells under similar reservoir conditions. Oil production from horizontal wells was increased by four folds on average in comparison with vertical well completion.
How Farmers, Graziers, Miners, and Gas Industry Personnel See their Potential for Co-existence in Rural Queensland
Authors: Everingham J.. , Collins N.. , Rifkin W.. , Rodriguez D.. , Baumgartl T.. , Cavaye J.. , Vink S.. 
Published: November 2013

Abstract
Rapid expansion of the coal seam gas (CSG) sector in Queensland has fuelled debate on the sector's contributions to community sustainability in a rural economy dominated by farming of food and cotton, cattle grazing, coal mining, and a modest level of tourism. For example, will the impacts of CSG extraction on surface and groundwater have sustained negative impacts on the growing of grain, and if so, what should be expected of the CSG industry today?
The intensity of debate has been accompanied by an array of operating conditions placed on CSG projects by the state government, extensive media coverage, and a focus on what it takes to maintain a ‘social license to operate’. Such a context is a challenge for resource companies committed to sustainability principles and to contributing to the social, economic and institutional development of the communities in which they operate as well as to the conservation of biodiversity and integrated approaches to land use planning.
In this context, our research has explored perceptions of the social and environmental impacts in two local government areas of rural Queensland. We surveyed and interviewed stakeholders affected by – and/or influential in – decision making and management of mining, CSG extraction, and agriculture in these areas. We asked their views on the state of the environment, the economy, social fabric, human capital, and local infrastructure, comparing today to five years ago. Their responses reveal how this contested arena harbours ‘wicked’ problems: issues that are hard to formulate in simple terms and where every potential solution has irreversible consequences. Our findings suggest further that successful co-existence of multiple industries and a social license to operate for CSG companies depend on effective management by resource companies, and by regulators, of operating practices, off-site impacts, and the distribution of benefits.
Chemostratigraphy and Sequence Stratigraphic Investigation of the Lower Silurian - Upper Ordovician Hot Shale, Southeastern of the Sichuan Basin
Authors: Wright Milly , Mu Guoyan , Wang Shiqian , Liu Bao , Davies Emma , Singh Navpreet 
Published: November 2013

Abstract
The southeastern Sichuan Basin is potentially one of the most prolific Shale Gas play in China. There is an obvious and pervasive stratigraphic correlation (high Gamma reading) at the lower Longmaxi Formation, which has been defined as the Hot Shale interval. However, it is difficult to make a meaningful detailed geological correlation within the Hot Shale interval due to relative poor data coverage of seismic and petrophysical log signatures.
Chemostratigraphy under the right geological setting is a proven tool that uses changes in bulk elemental composition to understand controls on reservoir quality, such as sediment provenance (proximal or distal) and paleo-environment in order to establish a chemostsratigraphic correlation for a given interval. For this study, a total of 377 cuttings and 20 core samples from the Upper Longmaxi, Lower Longmaxi to Wufeng (Hot Shale) and Linxiang/Baota formations of 4 exploration wells have been analyzed using ICP-OES and ICP-MS. Final integrated analyses have been made by combining with petrophysical logs, TOC, X-Ray Diffraction (XRD), petrography and Scanning Electron Microscope (SEM) data.
Prior to any interpretation, cutting sample quality was checked by comparison between chemical gamma (using U, K and Th data from the sample) and downhole gamma which suggested the cutting samples were largely representative of the formation drilled. Elements and element ratios can be directly linked to the XRD data which reflects the influence of sediment lithology/ mineralogy variation, it also demonstrates the elemental data is qualified to be used.
The enrichment factor of vanadium (EFV), which is sensitive to changing paleo-environments, suggests the lower Hot Shale was deposited in an overall more anoxic environment compared to the overlying and underlying formations. Within the Hot Shale interval, there is a positive relationship between TOC and EFV, indicating that TOC preservation is predominantly controlled by changes in paleo-environmental settings in the southeastern Sichuan basin. It further implies that EFV can also be used as a proxy for modeling TOC to assist in predicting lateral changes of paleo-environment between widely spaced data points.
Changes in the relative amount of terrigenous input (TiO2 + Al2O3 + K2O + Na2O) and biogenetic silica (SiO2/Zr) are also modeled, the former being related to changes in sediment provenance and the latter to depositional conditions. Terrigenous input increases upward with the lower Hot Shale having lower terrigenous content indicating a period of sediment starvation in relatively deep water. The high biogenic silica contents in the lower Hot Shale interval are consistent with the pervasive presence of sponge spicules in the microscope view of thin sections. The high biogenetic silica contents results in the sediments being more brittle, thus favorable for Hydraulic Frac Stimulation.
Post-Shutdown Recovery Behavior of Horizontal Coalbed Methane Wells in the Bowen Basin
Authors: Gilbert Tonna , Ali Ehtesham , Mazumder Saikat 
Published: November 2013

Abstract
A number of coalbed methane (CBM) to liquefied natural gas (LNG) projects are currently advancing in Australia, among which is the Arrow LNG project. To ensure reliable supply to an LNG plant, production availability of the integrated CBM system consisting of a large amount of wells and production facilities needs to be understood, including the behavior of CBM wells after planned and unplanned shutdowns. This paper provides an analysis of post-shutdown recovery behavior of horizontal CBM wells based on a large volume of field data. There is no known published work on shutdown recovery for CBM wells to date, so there are no comparison data.
Arrow Energy has produced CBM for domestic consumption since 2004 and currently supplies about 20 per cent of Queensland's gas from fields in the Bowen and Surat basins. A shutdown recovery analysis is conducted on Arrow's Moranbah Gas Project (MGP) in the Bowen Basin. Field data for 6,436 shutdown periods are used, including: gas rates, water rates and bottomhole pressures (BHP). The following effects on recovery times are analyzed: shutdown duration, pre-shutdown water rate, pre-shutdown gas-water ratio, and pre-shutdown producing days.
The results indicate that approximately 70% of wells, shutdown for one day, return to 90% of their previous gas rates within one day. Approximately 20% wells recover in a week and the remaining 10% wells come back to 90% of original rates within 2 months. Furthermore, shutdown periods longer than five days have significantly higher recovery times. Wells with a lower water rate and higher gas-water ratio before the shutdown return to their pre-shutdown gas rate faster than wells with a higher water rate and lower gas-water ratio. Also, late life wells recover faster than wells in early production life.
These findings are critical for planning well shutdown and ramp-up strategies (well classifications and priority lists) to manage required gas supply during the operational phase of integrated CBM-LNG projects.