bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Temperature on the Galvanic Corrosion in Multi-Material System in Seawater
Authors: Wang Chun Li , Wu Jian Hua
Published: April 2015

The galvanic corrosion behavior of titanium (TA2)/Cu-Ni alloy (B10)/low alloy steel (921A) multi-material system has been studied using a zero-resistance ammeter (ZRA) in seawater at different temperatures. After the tests, the surface morphologies of the samples were detected by SEM. Results showed galvanic corrosion behavior of TA2/B10/921A fulfill the mixed potential theory, 921A acts as the anode and both TA2 and B10 act as the cathodes. The effect of temperature on the galvanic corrosion is important, the corrosion rate increases with increasing temperature.
The Impact of Generalized Stacking Fault Energy on the Mechanical Properties of Shuffle Dislocation in Zigzag Single-Walled Carbon Nanotubes
Authors: Zhang Hui Li , Tong Lu Mei
Published: April 2015

The calculation of generalized stacking fault energy for covalent materials exists several relaxation methods. And the modification factor of the restoring force should be different for different relaxation. In order to study the impact of generalized stacking fault energy on the mechanical properties of dislocations, the dislocation energy, Peierls barrier and Peierls stress of shuffle dislocation in zigzag single-walled carbon nanotube (SWCNT) under different modification factors are studied by the improved Peierls-Nabarro (P-N) theory. It is found that the misfit energies decreased, and the strain and total energies increased with increasing of the modification factor Δ. With the modification factor Δ of the restoring force changes from -0.2 to 0.5, the dislocation energy changes from 17.4eV to 19.3eV. The Peierls barriers Ep and σp Peierls stresses increased first and then decreased and the results are not as same as we thought. The impact of generalized stacking fault energy on mechanical properties of dislocations is not so simple as we thought and need to be further studied.
The Influences of Annealing Temperatures on the Properties of HfO2 Thin Film and the Fabrication of SiO2/HfO2 Distributed Bragg Reflector
Authors: Tzou Wen Cheng , Kuan Hon , Chuang Kai Yang
Published: April 2015

In this study, HfO2 thin films were deposited onto the Si substrates by RF magnetron sputtering system. After deposition, the HfO2 thin films were then heated by a furnace thermal annealing process in air and at 400-700oC. The surface morphologies and crystalline characteristics of the HfO2 thin films were investigated by using SEM and XRD patterns. The grain sizes and crystalline phases increased with rising annealing temperature. In addition, the SiO2/HfO2 distributed bragg reflector (DBR) was used for improving the external quantum efficiency of the GaN-based LEDs. The output power of LEDs with 9-pair SiO2/HfO2 DBR and with Ag mirror+6-pair SiO2/HfO2 DBR were increased by approximately 10.6% and 7%, respectively, as compared with the LEDs without SiO2/HfO2 DBR.
The Multiband Fractal Antenna on Polymer Substrate Prepared by Using Inkjet Print Technology Based on Silver Nanoparticles
Authors: Matyas Jiri , Olejnik Robert , Vlcek Karel , Slobodian Petr , Urbanek Pavel , Krcmar Petr , Munster Lukas
Published: April 2015

This paper described the use of inkjet printing to design multiband fractal antenna based on Sierpinski arrowhead curve architecture. The antenna is printed using silver nanoparticles on a plastic substrate PET (Polyethylene terephthalate). Using a combination of printing technology and fractal geometry to achieve very advanced parameters in three frequency bands 650 MHz, 1,57 GHz and 2,5 GHz. Multiband antenna may find application in specific portable devices, where it would be possible to implement the antenna housing facilities in the form of printing.
Extraction of Astaxnathin from Portunus trituberculatus Using Ionic Liquids as Additives of Extraction Solvents
Authors: Lee Yu Ri , Woo Seung Buhm , Row Kyung Ho
Published: April 2015

Astaxanthin is a carotenoid red pigment in yeast, microalgae, shrimp and crab, and has strong antioxidant activity. In this work, an effective and accurate method was developed for the extraction of astaxanthin from Portunustrituberculatus with ionic liquids as extraction additives. 47.30 mg/g of astaxanthin in extracts was detected by C18 column with a mobile phase consisting of acetonitrile-chloroform-methanol-water (71:22:4:3, v/v).
Sonochemical Co-Precipitation Synthesis of Gallic Acid-Modified Magnetite
Authors: Rahmayanti Maya , Santosa Sri Juari , Sutarno Sutarno
Published: April 2015

Gallic acid-modified magnetites were synthesized by one and two-step reactions via the newly developed sonochemical co-precipitation method. The two-step reaction included the formation of magnetite powder and mixing the magnetite powder with gallic acid solution, while the one-step reaction did not go through the formation magnetite powder. The obtained gallic acid-modified magnetites were characterized by the Fourier Transform Infrared (FTIR) spectroscopy, the X-Ray Diffraction (XRD) and the Scanning Electron Microscopy (SEM). More over, the magnetic properties were studied by using a Vibrating Sample Magnetometer (VSM). The characterization results showed that there were differences in crystalinity, surface morphology and magnetic properties of products that were formed by one and two-step reactions.
Kinetics of Enzymatic Hydrolysis of Cellulose Using Aspergillus niger
Authors: Mulyaningtyas Akida , Ningsih Ratna , Syamsiah Siti , Sarto Sarto , Sediawan Wahyudi Budi
Published: April 2015

This study aimed to analyze the kinetics of enzymatic hydrolysis of cellulose. Cellulase enzyme was obtained from Aspergillusniger grown on filter paper and the hydrolysis process was carried out in solid state. The kinetic reviewed here was the relationship between glucose production and cellulose mass reduction to optimize the parameters of Monod equation at various moisture levels.
Enhanced the Negative Charges of Antheraea pernyi Silk Fibroin by Methylglyoxal Modification
Authors: Li Jing , Zhang Ceng , Zhang Yi , Yu Yan Ni , Luo Jing Wan , Li Ming Zhong
Published: April 2015

Antheraea pernyi silk fibroin has favorable biocompatibility, good bioactivity and controllable biodegradability, meeting the basic requirements of controlled drug release carriers. Enhancing the negative charge of silk fibroin could further increase the encapsulation and loading efficiency of positively charged drugs. In this study, Antheraea pernyi silk fibroin was chemically modified by methylglyoxal in aqueous solution. The electric charge properties of Antheraea pernyi silk fibroin were examined to characterize the modification, the results indicated that the isoelectric point of Antheraea pernyi silk fibroin decreased from 4.5 to 3.9, and the zeta potential reduced from-11.7 mV to-12.8 mV. Amino acid analysis and 1H-NMR spectra showed that arginine residue of Antheraea pernyi silk fibroin side chain was modified by methylglyoxal for enhancing negative charge of silk fibroin. These results suggested that methylglyoxal-modified Antheraea pernyi silk fibroin could be considered as a potential starting material in loading positively charged drugs.
Steam Reforming of Glycerol for Hydrogen Production over Ni Catalysts Supported by CeO2-Al2O3 Xerogel
Authors: Kamonsuangkasem Krongthong , Therdthianwong Supaporn , Therdthianwong Apichai
Published: April 2015

The Ni catalysts supported by CeO2-Al2O3 xerogel were prepared by sol-gel method. The effect of hydrolysis ratio (R at 16.5 and 165) on CeO2-Al2O3 textural properties and phase formation were investigated. The results revealed that the porous texture and the Ni crystalline phase can be controlled by adjusting the hydrolysis ratio. A high surface area and small Ni crystallite size were obtained by using the hydrolysis ratio of 16.5. For hydrogen production via glycerol steam reforming, the Ni catalyst supported on CeO2-Al2O3 xerogel showed a better catalytic performance than that supported on commercial alumina. The promoted Ni catalyst supported on commercial alumina suddenly deactivated after first 12 h, whereas that on Al2O3 xerogel performed the catalytic stability more than 20 h. This demonstrated that the catalyst prepared by sol-gel method is an interesting catalyst for using in the glycerol steam reforming because of the catalytic stability enhancement.
Preparation, Surface Activity and Application of Fluoro-Spreading Agent
Authors: Shi Hong Xin , Fu Yu Teng , Shen Hai Min , Wu Hong Ke
Published: April 2015

Ammonium perfluoro-2,5-bis (trifluoromethyl)-3,6-dioxopelargonate (FY1) was synthesized from perfluoro-2,5-bis (trifluoromethyl)-3,6-dioxopelargonic acid and ammonia in ether, and was characterized by IR and 1H NMR. Its surface activity and spreading performance on gasoline were investigated in detail. The critical micelle concentration (CMC) of FY1 in aqueous solution was 0.25 g / L, and the surface tension at CMC (ڃcmc) was 17.25 mN / m. The aqueous solution of FY1 could spread on the surface of gasoline, but the aqueous solution of FY1 mixed with sodium dodecyl benzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), n-octanol, 2-ethyl hexanol or VF respectively could not spread on gasoline. However, the aqueous solution of two or three components of FY1 with anion fluoro-surfactant Intechem-1 and SDS or n-octanol could spread on gasoline, and the biggest covering degree on gasoline reached 80.2% in 10min. It can decrease the volatilization of gasoline and can be employed to develop a new aqueous film-forming foam for oil-fire fighting.
Saccharose as a New Space Holder Material for Porous Titanium Implant Formation
Authors: Adamek G. , Koper J.K. , Jakubowicz J.
Published: April 2015

This paper investigates the properties of Ti scaffolds with a porosity of 73%. In the processing route, a new space holder material was applied - saccharose, commonly known as table sugar. Porous Ti was made by the dissolution of sugar crystals from the Ti-sugar green compact and final sintering of the remaining Ti scaffold. The sintered scaffolds showed uniform pore distribution. The pores had polyhedral shape and their dimensions reached 1 mm. The scaffolds were made and investigated with respect to possible medical applications. After all processing stages, the surface was oxidized and showed average wettability with the lowest wetting angle of 81.5o, which was strongly correlated with the condition of the surface. The chemical etching in an HF solution resulted in a strong wettability improvement. Due to very high porosity, the compression strength (1.48 MPa) and Young’s modulus (33.7 MPa) of the scaffolds were relatively low.
Characterization of Thermal Conductivity and Viscosity of Nanofluids with Aqueous Base Fluids
Authors: Nah Kim Soon , Hung Yew Mun
Published: April 2015

Two different nanofluids (SiO2 – EG/DW and SiO2 – DW) with various volume fractions are prepared by dispersing SiO2 nanoparticles (< 20 nm) into two different types of base fluid: distilled water and ethylene glycol/distilled water mixture. The effective thermal conductivity and viscosity of nanofluids are characterized and compared over a temperature range of 25oC - 50oC. It is found that the effective thermal conductivity and viscosity of nanofluid are influenced by the nanoparticle volume fraction and the operating temperature. The thermal conductivity of the SiO2 nanofluids with different volume concentrations increases as temperature increases while the viscosity decreases with the increasing temperature. The base fluid alters the characteristics of both the thermal conductivity and viscosity of nanofluid. Over the same range of operating temperature, the effective thermal conductivity and viscosity of SiO2 – EG/DW nanofluid manifest stronger dependency on the nanoparticle concentration compared to those of water-base-fluid nanofluid.
Potentiodynamic Polarization Studies of Glycerin in Platinum Electrodes
Authors: Beltrán-Prieto Juan Carlos , Slavík Roman , Kolomazník Karel
Published: April 2015

A three electrode system was used for the analysis of potentiodynamic polarization studies of glycerin in platinum electrodes. Particular attention was devoted to the estimation of diffusion coefficient of glycerin in platinum electrodes by the use of electrochemical techniques such as the sweep of the potential. Cyclic voltammograms were recorded at different sweep rates (0.01 and 0.07 V·s-1). Randles-Sevcik equation was taken into consideration and a linear relationship was found between the peak current and the square root of the voltage sweep rate from where the value of diffusion coefficient could be determined. The values of Tafel constants, useful in the understanding of electrochemical reaction kinetics are also reported in the present paper.
Mechanical Behavior of Multi-Pylon Steel Cable-Stayed Bridge
Authors: Zeng Ming Gen , Dai Chang Yuan , Su Qing Tian
Published: April 2015

The structure form of the multi-pylon cable-stayed bridge is greatly different from that of conventional cable-stayed bridge with twin-pylon or single-pylon, which induces the mechanical behavior of multi-pylon cable-stayed bridge is also much different from that of cable-stayed bridge with twin-pylon or single-pylon. Combined with the Fanli Bridge in Yixing city of Jiangsu province, the load carrying performance of this type bridge is analyzed. The analytical results show that the internal force distribution pattern of main girder in this type cable-stayed bridge is different from that of in conventional cable-stayed bridge, also the internal force distribution pattern of both the different steel pylons in same bridge and the steel columns in same pylon are distinctive.
Artificial Weathering Analysis and Mechanical Behavior of Geotextiles Used for Coast Erosion Control and Beach Restoration
Authors: Ríos-Soberanis Carlos Rolando , Rodriguez-Laviada R. , Perez-Pacheco E.
Published: April 2015

Nowadays geotextiles play a significant part in coastal protection and erosion prevention design and maintenance techniques. The growth in their use worldwide as geotubes for recovering damaged coastal due to its easiness of manipulation and excellent mechanical properties has been extraordinary. Considering that applications of geosynthetics are usually outdoors, the degradation of polymers must be taken in account when selecting polymeric textiles. There are many environmental factors, which influence aging mechanisms of geotextiles such as UV radiation, temperature, humidity, etc. However, a multiple exposures, such as a combination of moisture and heat or oxygen and light, can result in accelerated deterioration. This paper is related to mechanical behavior and durability consideration that geotextiles must withstand in order to be applied as geotubes for coast erosion and beach regaining. The paper provides an overview of the current erosion in the Yucatan coast and the solutions for shoreline protection as well as the effect of geotextile architecture on mechanical properties.
Design Proposal for Concrete Cover Separation in Beams Strengthened by Externally Bonded Tension Reinforcement
Authors: Wang Sai Sai
Published: April 2015

Existing experimental observations have shown that the application of externally bonded reinforcement (steel plate, FRP laminate, overlay, etc.) to strengthen RC structures can lead to brittle failures involving debonding of the external reinforcement before the design load is reached with classical failure modes. The design approach to determine the strengthening material and its area should avoid these premature failures. In this study, an analytical model developed for the overlay strengthening by the authors is firstly proved to be applicable for the steel plate or FRP laminate strengthening by comparing the analytical and experimental failure load as well as the failure mode of the strengthened beams reported in the literature. Then the main parameters involved in the process of concrete cover separation are identified and a simple criterion is proposed for prediction of premature failure.
Surface Roughness Optimization in Turning Operation Using Hybrid Algorithm of Artificial Bee Colony with RSM
Authors: Ahsan Habib Mohammad , Patwari Md. Anayet U. , Khan Koushik Alam , Amanullah Tomal A.N.M.
Published: April 2015

For cost reduction and quality improvement of machining products, optimum output machining parameters such as material removal rate, tool wear ratio and surface roughness is very essential. Moreover, these output parameters are strongly depends on the precision of the machine tool as well as the input machining parameters. In this paper, a hybrid model of Artificial Bee Colony (ABC), which is motivated by the intelligent behavior of honey bees with Response Surface Methodology (RSM), has been developed for optimizing the surface roughness of stainless steel during turning operation. The predicted optimal value of surface roughness of stainless steel is further confirmed by conducting supplementary experiments. Finally, the performance of this algorithm is evaluated in comparison with desirability analysis. The performance of ABC is at par with that of desirability analysis for different parametric conditions.
Identification of Friction Characteristics and Flow Stress of 0.45% Carbon Steel during Cutting Process
Authors: Wahab Norfariza , Sasahara Hiroyuki
Published: April 2015

Nowadays, numerical simulation technique is used to predict machining states such as cutting forces, stresses and temperature distribution. However, it is difficult to simultaneously estimate the stress-strain relationship of the workpiece and friction characteristics between tool-chips during cutting process. The aim of this study is to propose a new method to identify friction characteristics and flow stress of 0.45% carbon steel for FEM simulation during cutting process. Shear friction equation had been applied to estimate the friction characteristics and the Johnson-Cook (JC) constitutive equation work flow stress model was considered as a function of strain, strain rate and temperature to determine characteristics of workpiece flow stress. As a result, friction characteristics and flow stress of 0.45% carbon steel during cutting process had been estimated applying this proposed method.
Effect of Heat Treatment on the Microstructure of Plasma Spray SUS316L Stainless Steel Coating
Authors: Wang Jin , Shinozaki Nobuya , Zeng Zhen Su , Sakoda Nobuaki
Published: April 2015

A study of the effects of heat treatments of plasma sprayed SUS316L stainless steel coatings was performed. The stainless steel coatings were treated at the conditions of 1273 K and 1373 K for 45 minutes in flowing argon. The effectiveness of the heat treatment was determined using an electron probe microanalyzer (EPMA). The results indicated that the heat treatments were able to significantly affect the composition and the microstructure. After the heat treatment, the interconnected micro-pores were found to appear in the large-scale rod-like oxide in the coating and the content of chromium and manganese in the oxides became higher than that in the as-sprayed coating. The heat-treatment became more effective with increasing temperature.
Effect of Na2SO4-V2O5 Mixture on Y2O3 Stabilized ZrO2 Thermal Barrier Coatings Exposed at High Temperature
Authors: Qureshi Imran Nazir , Shahid Muhammad , Khan Aamir Nusair
Published: April 2015

Yttria stabilized zirconia thermal barrier coating (TBC) along with CoNiCrAlY bondcoat was deposited using air plasma spray on Inconel-X750 superalloy. The coated samples were exposed at 9500C in a mixture of Na2SO4 and V2O5. The exposed specimens were investigated using XRD and SEM. The formation of spinel and perovskite structures was revealed at the interface of topcoat and the bondcoat. XRD analyses of the samples confirmed phase transformation of the tetragonal zirconia into monoclinic zirconia and yttrium vanadate.
Mathematical Formulation of the Global Coefficients of Transmission and Reflection of Ultrasonic Waves in Bi-Phase Porous Medium
Authors: Freiha Georges , Othman Hiba , Owayjan Michel
Published: April 2015

The study of signals propagation inside porous media is an important field especially in the biomedical research related to compact bones. The purpose of this paper is to determine a mathematical formulation of the global coefficients of transmission and reflection of nondestructive ultrasonic waves in any bi-phase porous medium. Local coefficients of transmission and reflection on the interface of the porous medium will be determined based on a study of boundary conditions. The behavior of different waves inside the porous medium will be developed so that we can derive a new formulation of global coefficients that takes interior phenomena into consideration. Results are found independently of the geometrical and physical characteristics of the medium. Note that this study is based on normal incident ultrasonic wave propagation.
Vacuum Brazing Incoloy 800 Using the Copper Foil
Authors: Wang Cheng Yen , Shiue R.K.
Published: April 2015

The purpose of this research is focused on vacuum furnace brazing Incoloy 800 (IN-800) using the copper filler foil. Microstructural evolution and shear strength of brazed joints for various brazing conditions has been evaluated in the experiment. The Cu-rich matrix dominates entire brazed joint. The width of Cu-rich matrix is decreased with increasing the brazing temperature and/or time. Average shear strength of the joint is approximately 215 MPa. Dimple dominated fracture is widely observed for the specimen brazed below 1160 oC. However, cleavage dominated fracture is found for the specimen brazed at 1200 oC. It is advised that copper brazing IN-800 alloy should be confined below 1160 oC.
Nanotechnology for Photovoltaic Cells and Energy Efficiency
Authors: Di Salvo Santina
Published: April 2015

Abstract. The intent of this paper is to connect science and technology in order to demonstrate how, in the field of on photovoltaic technologies, thin film solar cells have been the focus of many research facilities in recent years that are working to decrease manufacturing costs and increase cell efficiency. New research suggests that it might be possible to add a nanoscopic relief pattern to the surface of solar cells that makes them non-reflective significantly boosting efficiency and at the same time making them highly non-stick and self-cleaning. The paper presents the challenges and approaches to engineer the active layer of the cell, in order to obtain cells made up of components assembled with precision on the nanometer scale and with such properties as to increase the yield of conversion of solar radiation into electricity.
Performance Analysis of a WCDMA System Model in a Low Mobility and Indoor Environment with Channel Coding over Additive White Gaussian Noise Channel
Authors: Ombongi Filbert O. , Kibet Philip L. , Musyoki Stephen
Published: April 2015

This paper has analyzed the performance a Wireless Division Multiple Access (WCDMA) system model at a data rate of 384kbps and 2Mbps over an Additive White Gaussian Noise (AWGN) channel. The signal was modulated by Quadrature Phase Shift Keying (QPSK) and Quadrature Amplitude Modulation (QAM) with modulation order, M=16. The performance of the system was enhanced by implementing convolution coding scheme. This study was important as it formed a basis through which the performance analysis can be extended to Long Term Evolution (LTE) networks which have data rates starting from 1Mbps to as high as 100Mbps.The performance of the WCDMA at these data rates was seen to improve when convolutional coding scheme was implemented. Since the Shannon capacity formula depends on the BER of a system then this improvement means an additional capacity in the channel and this can accommodate more users in the channel. The results have further shown that the choice of a modulation technique depending on the throughput required affects the BER performance of the system. Therefore, there must be a trade-off between the throughput required, the modulation format to be used and the pulse shaping filter parameters.
Perspectives of Digital Broadcasting in Nigeria - Discussion of Challenges and Solutions
Authors: Enwere Chinotu Micah , Nnebedum Vincent I.
Published: April 2015

Nigeria with a population of over 140 million, with 187 radio stations, and 143 television stations, the largest in the African continent, quickly accepted the technology switchover system in broadcast as it will seriously affect the people and Government of the country if not managed. Nigeria joined the global digitalization train, with specific switchover date fixed at June 17, 2012, three years ahead of the International Telecommunication Union, ITU, global deadline set date for 2015 for the entire broadcasting stations in the world to go digital. The truth is, Nigeria never went digital with respect to the June 17, 2012 switchover date. A new switch over date of 2015 was set, but there is doubt if the new target date could be met. The strengthening of public awareness and education on what digitalized broadcasting involves and what is needed to be put in place by the government, stakeholders and consumers for a successful transition to digital broadcasting is still low. This article focuses on Digital Broadcasting in Nigeria: What is it and what is needed to be put in place for a successful takeoff.
Relationship between the Geometric Properties and the Shear Modulus of an Adhesive, and Optimization of Mechanical Behavior of Bonded Assemblies
Authors: Abdelkader Ghazi
Published: April 2015

The bonding is a method of maintaining solidly and permanently attaching two surfaces, similar or different of materials by adhesive.It is known that several parameters influence the bounding quality such as the size and the intrinsic properties of the adhesive and the plate. The experimental design methodology is used to investigate the effects of lap length, thickness of the adhesive, the shear modulus of the adhesive and lap width in order to achieve an optimization of the bonding operation. This optimization allows us to identify the most influencing parameters on the bounding performances.In order to ensure the minimal stress; an interaction study has found different combinations of factors.
Wind Turbine Wake-Redirection Control at the Fishermen's Atlantic City Windfarm
Authors: Churchfield Matthew J. , Fleming Paul , Bulder Bernard , White Stanley M.
Published: April 2015

In this paper, we will present our work towards designing a control strategy to mitigate wind turbine wake effects by redirecting the wakes, specifically applied to the Fishermen's Atlantic City Windfarm, proposed for deployment within the next few years off the shore of Atlantic City, New Jersey. As wind turbines extract energy from the air, they create low-speed wakes that extend behind them. Full wake recovery to the undisturbed wind speed takes a significant distance. In a wind energy plant the wakes of upstream turbines may travel downstream to the next row of turbines, effectively subjecting them to lower wind speeds, meaning these waked turbines will produce less power.

Wakes can be redirected laterally to some degree, though, by applying yaw misalignment to the wake-generating turbine (i.e., not pointing the turbine directly into the wind). Yaw misalignment causes part of the rotor thrust vector to be pointed in the cross-stream direction, deflecting the flow and the wake in that direction. Yaw misalignment reduces power production, but the global increase in wind plant power caused by decreased wake effects creates a net increase in power production. With the increase in power can come an increase in fatigue loads, though, caused by yaw misalignment. However, if misalignment is applied properly, and it is layered with individual blade pitch control, the load increase can be mitigated. To explore the idea of wake redirection, we used high-fidelity computational fluid dynamics.

Our computational fluid dynamics simulations predict that when winds are aligned with the row, which is one of two predominant wind directions, wake-redirection control can create a 10% increase in energy capture efficiency. This means that, for a given wind energy plant's electrical generating capacity, if wake-redirection control were employed, turbines could be more closely spaced, thereby reducing the watersheet area of the wind plant. Likewise, for a given watersheet area, the total electrical generating capacity can be increased.

In this paper, we discuss the concept of wake redirection through wind turbine yaw misalignment and present our computational fluid dynamics results of the Fishermen's Atlantic City Windfarm project. We also discuss the implications of wake-redirection control on annual energy production and fatigue loads, as well as plans to implement wake-redirection control at Fishermen's Atlantic City Windfarm when it is operational something not done before at a commercial wind plant.
Manifa Oil Field Development Program – Onshore And Offshore Shallow Water Development
Authors: Aldossary Ghassan
Published: April 2015

The Manifa Oil Field is located approximately 200 km northwest of Dhahran and lies mainly offshore in shallow waters. The field was discovered in 1957, and was brought on-stream in 1964. Due to low crude oil demand, the production from the Manifa Oil Field was stopped in 1984, and the facilities were mothballed in 1985. In 1995, the existing GOSP facilities were dismantled.

In 2006, Saudi Aramco embarked on the development of a mega-project at the Manifa shallow water offshore oil field to develop the field and construct the required infrastructure and facilities for a production capacity of 900,000 barrels per day of Arab Heavy crude oil. This new development at Manifa can be classified as being a true grassroots venture, as it converts an offshore field into an onshore project, which is the largest extended reach project of its kind in the world.

During the project execution, the team navigated through many challenges considering the extremely large magnitude of the program. Such challenges include oil field development options, the integration of the drill sites with the pipeline system, the causeway design and options, the crude transportation pipelines configuration, compatible facilities metallurgy, the electrical power system architecture and the collection, transportation, integration, analysis and reporting of data collected from the drill sites through the massive RTU and SCADA systems.

Once the conceptual development design for the program was complete and agreed by all stakeholders, the sequence of facilities completion had to be planned in a manner to support the project completion schedule. The integrated activities schedule had to interlink with the well's drilling activities, flow lines installation and the onshore plant readiness simultaneously, overcome the limited space in the man-made island, work through simultaneous operations between drilling and the construction agency, while also monitoring the environmental marine life in the shallow waters of the Manifa bay and enforcing high levels of safety standards by performing periodic safety drills.

This paper covers mainly the design of the offshore facilities and the Manifa Causeway and does not discuss in detail the onshore facilities and infrastructure, which is another large aspect of the overall Manifa Program.
Adaptation of Coiled Tubing for Deep and Ultra-Deep Water Commissioning: Focus on Fatigue and Ancillary Equipment
Authors: LIROLA François , PIONETTI François-Régis
Published: April 2015

The installation of flowlines in ever deeper and remote areas requires the usage of specific technologies in order to carry out pre-commissioning operations. As the water depth increases, the weight of the conventional equipment to be deployed to perform the required operations becomes a major issue and alternate solutions are thus required. An option lies in using Coiled Tubing. Coiled Tubing consists of continuous pipe that has been coiled around a reel and can be deployed and recovered according to operational needs.

So far, offshore operation of coiled tubing has been limited to small diameters and to short operational duration. The pre-commissioning operations can require the Coiled Tubing to be deployed several times for durations sometimes exceeding a month, and also requires larger diameters (typically 3.5"). As the duration of operations increases, a suitable way of assessing the fatigue of Coiled Tubing and of mitigating is required.

In order to address these challenges, SAIPEM has initiated an extensive fatigue campaign aiming at characterizing the fatigue behavior of Coiled Tubing under combined Plastic and Elastic fatigue. This testing campaign is being performed on actual coiled tubing samples made of CT-80 steel. The paper will present an overview of the testing matrix as well as an insight on the results obtained during this fatigue testing campaign.

In addition, in order to mitigate fatigue during offshore operations, SAIPEM has also developed an innovative bend stiffener design in order to control the stress levels in the Coiled Tubing at the hang-off location on the ship. This bend stiffener design allows for safe and easy operation of Coiled Tubing offshore while allowing the deployment of all required equipment and doesn't interfere with the deployment and recovery of the coiled tubing. A feedback on the utilization and performance of such equipment offshore will be provided.
Low-Heave Semi-Submersible Enabling Dry-Tree Field Development
Authors: Muehlner Edmund , Banumurthy Surya
Published: April 2015

The objective of this paper is to present the new Offset-Pontoon Semi-submersible (OPS) for use as a drilling and production platform. The new semi-submersible features pontoons that are offset to the outside of the columns which lends the vessel a low heave response and enables the use of top tension risers with dry trees. Other advantages of the OPS are a shallow quayside draft, a large payload capacity and the ability to operate in ultra-deepwater.

The primary design challenge for dry-tree semi-submersibles is to make their heave motions compatible with the stroke range of existing riser tensioners. Increasing the vessel draft to reduce the heave motions is constrained by installation requirements and stability limits. However, vessel heave motions can be reduced by modifying the hull shape.

The OPS has a longer heave natural period and a smaller heave response than a conventional deep-draft semi-submersible. The heave performance of the OPS was compared with a conventional semi-submersible using frequency- and time-domain analyses.

In this paper we also present a design study of the OPS for dry-tree field development offshore Brazil. The vessel was sized to support thirteen top-tension risers and a 30,000 ton topside. The paper describes design of the vessel and its global performance. Focus of the study was the wellbay loayout and the tensioner stroke requirements. For the selected design case we found ram-style riser tensioners with a stroke range of 30 ft sufficient. Integration of the hull and topside by float-over is also described.
Intelligent Wired Near Bit Underreamer Connects Measurement While Drilling Tools to Rotary Steerable System While Eliminating the Under Gauge Rathole at TD
Authors: Valverde Eduardo , Goodwin Alex
Published: April 2015

Simultaneous drilling and hole enlargement is a common practice in deepwater Gulf of Mexico projects where tighter casing tolerances are required. Hole enlargement via underreaming is the most common practice, because it provides a larger diameter hole to ensure that casing reaches its required total depth (TD). Hole enlargement creates sufficient annular space to allow casing to be delivered to planned depth as well as for a properly executed cement job. The most accepted bottom hole assembly (BHA) design for hole enlargement while drilling (HEWD) places an underreamer above both the measurement while drilling / logging while drilling (MWD/LWD) and rotary steerable system (RSS) packages. This placement ensures proper installation of the activation ball in the underreamer and connectivity of the RSS and MWD/LWD so that directional work can be executed. However, this placement also leaves up to 200 feet (61 m) of under gauge rat hole to total depth (TD), forcing the operator in many cases to make a second dedicated run to underream the remaining under gauge rat hole.

An alternative underreamer technology that is gaining interest is designed to run directly above the RSS, but below the MWD/LWD package. Known as the intelligent wired underreamer, this design allows for a much shorter under gauge rathole to TD, while circumventing several common deployment challenges with conventional underreamers. Historically, placing an underreamer below the MWD/LWD prevented the operator from pumping an activation ball through the restricted internal diameter of the MWD/LWD tools. Another challenge of placing the underreamer near the bit is the fact that connectivity is severed between the MWD/LWD and RSS, which makes it impossible to use certain RSS in the BHA.

A deepwater operator drilled a development well in the Gulf of Mexico which required such a solution to simultaneously drill and enlarge the 18 1/8" and 16 ½" sections of the wellbore to 22" and 20", respectively. The intelligent wired underreamer, with its radio frequency identification (RFID) and pump-cycle activation capabilities, allowed the operator to run the underreamer directly above the RSS and below the MWD/LWD package and successfully activate and deactivate the underreamer, without ball drop. A wire through the underreamer connected the MWD/LWD and the RSS, providing full connectivity and directional control. And the use of an intelligent wired reamer in this application eliminated a potential round trip to ream the rathole and allowed the operator to successfully drill and ream both sections to planned TD.
Future Changes in Gulf of Mexico Hurricane Impacts
Authors: Done J. M. , Bruyère C. L. , Holland G. J.
Published: April 2015

Meeting industry demand for assessments of future changes in Gulf of Mexico hurricane impacts is a challenge that extends beyond simply improving hurricane science. There remains a need to translate the latest hurricane science to industry impact assessments. The National Center for Atmospheric Research is actively engaged in a collaborative project with the Research Partnership to Secure Energy for America, the CASE-EJIP JIP, and Willis Re to align the latest hurricane science with the requirements of industry.

Loading on structures in the Gulf of Mexico is a complex function of wind, wave, and current. Simple empirical relationships miss some of the essential physics, particularly under extreme conditions, resulting in errors in design criteria such as the 100-year load. To account for these important processes, a modeling approach is designed that reconstructs historical hurricane wind fields that are then used to drive dynamical wave and current models. Using this approach, historical hurricanes is simulated under current and future climate conditions, and potential future changes to wind, wave and current are assessed.

An alternative and complementary approach to assessing hurricane damage is developed. This approach uses empirical relationships between the large-scale environment and hurricane parameters that are known to cause damage (intensity, size and forward speed) to assess future hurricane damage. This approach projects a future decrease in mean tropical cyclone damage potential of 15 percent by the 2070s with a range of +2 percent to -57 percent. This combination of approaches is anticipated to lead to better planning guidelines that will enable improved design of structures and operating procedures, which in turn will provide more efficient future oil and gas production and aid in the minimization of environmental and safety risks.
Methodologies for In Situ Detection of Subsea Meter Fouling
Authors: Zanker Klaus
Published: April 2015

The increasing global importance of subsea production drives the need for better accuracy in subsea measurements to allow precise reservoir management while ensuring accurate royalty assessment and production allocation. The work described here resulted from the previous RPSEA Project 1301, which showed that flow measurement errors of 10 to 20 percent were possible when meters were subject to scale or erosion. The objective of this work under RPSEA Project 4304 is to identify ways of detecting fouling in multiphase and wet gas meters, so that corrective measures can be taken before large errors occur.

The effort consisted of two major parts:

An examination of the state of the art in sensor and meter technology was conducted for the purposes of detecting and/or quantifying meter fouling. A number of ideas were considered.

An evaluation of these and other technologies was performed to ultimately select the three most promising methods from the technology review. The criteria for choosing the most promising methods are discussed. The chosen methods were:

The results of these developments show promise, can be used in parallel and are discussed in the paper.
Offshore Production Units for Pre-Salt Projects
Authors: de Andrade Ana Maria Teixeira , Vaz Célio Eduardo Martins , Ribeiro Jônatas , Lopreato Luiz Guilherme Roquette , do Nascimento Rafael Fernando Soares
Published: April 2015

Petrobras and partners have been developing Brazilian Santos Basin Pre-Salt ultra-deepwater areas through the use of Floating Production Storage and Offloading Units (FPSOs), equipped with topside facilities designed to receive produced fluids and process them to generate end streams to export and injection.

The large hydrocarbon volumes in Santos Basin Pre-Salt areas, which have been successively confirmed by the results of exploratory and productions wells, have encouraged Petrobras and partners to choose an aggressive development strategy over a more conventional one. Based on this decision, FPSOs were chosen, mainly due to crude oil storage capability thus not requiring the construction of long-length oil pipelines, and also because of other characteristics that allow a short term completion with economic advantages. Therefore, the topside process plant conceptual design had to deal with uncertainties in the reservoir fluid compositions and production profiles. This means a wide range of CO2 and H2S contents, oil API gravity, flow rates and arriving fluid pressures and temperatures, in order to guarantee an adequate nominal capacity and turndown, and also the proper performance within the established design cases.

The main purpose of the topside facilities is to gather and treat the produced fluids to be sent ashore. The treated oil is routed to cargo tanks, the produced water is treated and discharged overboard, an dthe bulk treated gas stream is exported through a gas pipeline network, which allows to send the stream to three different gas processing sites onshore. The separated CO2-rich stream is injected back to the reservoir.

Besides the production units specially designed for Santos Basin Pre-Salt features, some Pre-Salt reservoirs from Campos Basin have been also being produced, by connecting new wells to existing production units. The main approaches regarding these units and its production in Campos Basin Pre-Salt are also part of the scope of this paper.

As a result of these different strategies and due to the daily efforts to overcome the forementioned challenges, more than six hundred thousand barrels per day of crude oil, as a monthly average, have been produced in Brazilian Pre-Salt areas, after only eight years since the early developments of the area.
The Contribution from an Operator's Global Subsea Hardware Standardization Program to 10K Subsea Hardware on Parque das Conchas (BC-10)
Authors: de Carvalho Thiago Palmeira Freire , Olijnik Luiz , Labes Alan
Published: April 2015

The Parque das Conchas field in Campos basin offshore Brasil is a phased ultra-deepwater heavy oil development tied to the Esp rito Santos floating, production, storage and offload (FPSO) vessel, moored at a water depth of 1,780-meters. The subsea system utilizes a subsea boosting and separation technology, enhanced recovery through water and gas injection, subsea sampling, enhanced vertical deepwater trees (EVDT), steel lazy wave catenary risers, and high voltage multiplexed electro-hydraulic steel tube umbilicals. During its nine year development since sanctioning, the professionals, installation contractors, commercial and contractual conditions have changed and played their role on the successful deployment of the subsea systems architecture. The project's successful track history to date is largely attributed to the development and consistent application of standardized subsea hardware throughout its three distinct and independently developed phases.

This paper addresses the standardized features applied to the 10,000-psi (10K) rated subsea system components at BC-10: EVDT systems and tooling, including the upper completion tools which allowed deployment through either a subsea or surface blow-out preventer; completion and intervention riser systems on the lower riser package; retrievable flow modules and flow meters; production and injection jumper kits; manifolds; subsea boosting and separation; subsea control modules; umbilicals and subsea distribution hardware. This paper also addresses how these features fit within the operator's global subsea hardware standardization program, and provides examples on how continuous improvement, lessons learned and innovations are implemented in that program.
Water Hammer in Upstream Production
Authors: Danielson Thomas J. , Gokcal Bahadir
Published: April 2015

Water hammer, or more properly ‘liquid hammer’ simulations are commonly performed with transient simulation software. However, care must be taken in the setup of such simulations to assure good fidelity with the field operation being simulated. Of critical importance is the realization that a sudden pipeline shutdown has a symmetry where a pressure reduction (which can easily result in the creation of a vacuum strong enough to pull gas out of solution, followed by explosive recompression of that resultant gas phase) occurs at the inlet of the pipe equal in magnitude to the pressure surge at the outlet. Much can be done with ‘pencil-and-paper’ calculations, including a worst-case estimate of surge pressures using the Joukowsky Equation. This equation can be further modified to account for elasticity, as would occur, for example, in a tanker loading hose – in fact, this modification is essential to obtain the correct behavior from the simulation models. This paper presents transient simulations, along with comparisons to pencil-and-paper equations and theory, to come up with a best-practices approach to water hammer modeling.