bluuebunny/crossref_metadata_2025 huggingface dataset:
A Thermodynamic Analysis of Tubular SOFC Based Hybrid Systems
Authors: Rao A. D. , Samuelsen G. S.
Published: July 2014

The goals of a research program recently completed at the University of California, Irvine were to develop analysis strategy for Solid Oxide Fuel Cell (SOFC) based systems, to apply the analysis strategy to tubular SOFC hybrid systems and to identify promising hybrid configurations.

A pressurized tubular SOFC combined with an intercooled-reheat gas turbine (SureCell™ cycle) is chosen as the Base Cycle over which improvements are sought. The humid air turbine (HAT) cycle features are incorporated to the Base Cycle resulting in the SOFC-HAT hybrid cycle which shows an efficiency of 69.05% while the Base Cycle has an efficiency of 66.23%.

Exergy analysis identified the superior efficiency performance of the SOFC component. Therefore, an additional cycle variation added a second SOFC component followed by a low pressure combustor in place of the reheat combustor of the gas turbine of the SOFC-HAT hybrid. The resulting Dual SOFC-HAT hybrid has a thermal efficiency of 75.98%.

The Single SOFC-HAT hybrid gives the lowest cost of electricity (3.54¢/kW-hr) while the Dual SOFC-HAT hybrid has the highest cost of electricity (4.02¢/kW-hr) among the three cycles with natural gas priced at $3/GJ. The Dual SOFC-HAT hybrid plant cost is calculated to be significantly higher because the fraction of power produced by the SOFC(s) is significantly higher than that in the other cases on the basis of $1100/kw initial cost for the SOFC. The Dual SOFC-HAT hybrid can only be justified in favor of the Single SOFC-HAT hybrid when price of natural gas is greater than $14/GJ or if a severe carbon tax on the order of $180/ton of CO2 is imposed while natural gas price remains at $3/GJ.
A Turbogenerator for Fuel Cell/Gas Turbine Hybrid Power Plant
Authors: Ali Sy A. , Moritz Robert R.
Published: July 2014

The Department of Energy has encouraged the development of high temperature fuel cells in partnership with industry. These fuel cells are primarily designed for stationary power. Integrating a fuel cell with a gas turbine produces a “hybrid” system, which enhances power output and efficiency, while reducing overall system cost. Recent DOE studies on Solid Oxide and Molten Carbonate fuel cells have confirmed that the fuel cell hybrids can generate 70+% plant electrical efficiency. The studies were focused on >20 MW hybrids. The first commercial hybrids using currently available stacks are expected to exceed 60% efficiency and are likely to be of the 1-3 MW class.

Existing gas turbines are not compatible with performance or life requirements of a “hybrid.” In order to achieve these goals, a purpose-designed gas turbine was deemed necessary, which would:

• Drive oxidant flow (normally air) through the stack and cycle

• Pressurize the stack to raise its power output and efficiency

• Minimize internal gas velocities and associated parasitic losses

• Reduce system cost through a simpler overall balance of plant configuration

• Enhance and simplify balance of plant and system integration process

• Provide a means for converting fuel cell exhaust heat to as bonus electricity

The benefits of a purpose-designed gas turbine are:

• Total power improvement from 20 to 50%

• Fuel efficiency improvement of 20-30% from a given stack system

• System capital cost reduction ($/kW) of up to 40%

• Life target of approximately 100,000 hours

Fuel cells are expected to be used extensively for distributed generation application in base load mode, running predominantly steady state. The design stack life in this operating mode is 100,000 hours. The design of a fuel cell compatible gas turbine has been initiated. Results of this project will be presented at the conference. Turbogenerator configuration studies are continuing, under contract number DE-FC26-00NT40914, for the US Department of Energy.
Qualification Testing the WR21 Intercooled and Recuperated Gas Turbine
Authors: English C. R. , McCarthy S. J.
Published: July 2014

The WR21 Intercooled and Recuperated (ICR) gas turbine has been developed to meet the future military needs for a fuel efficient, low cost of ownership, high power marine gas turbine. The engine is rated at 25.6MW (ISO) and has an outstanding pedigree derived from its two parent engines, the Rolls-Royce aero RB211 and Trent.

Having completed development in February 2000, a 3000 hour endurance test is now underway and a shock test is planned to qualify the engine for entry into service in the Royal Navy, United States Navy and French Navy. The 3000 hour endurance test commenced at DCN Indret, France in January 2001 and is planned to complete April 2002. Shock testing, conducted on the unrefurbished endurance engine, will complete in late 2002.

The three Navies have invested considerable time and effort in developing comprehensive running profiles that will thoroughly test the engine to the satisfaction of all parties. The first 1500 - 2000 hours will be conducted with the engine operating in the mechanical drive configuration, with the remaining running simulating the engine driving a conventional constant speed alternator.
Integration of the WR-21 Intercooled Recuperated Gas Turbine Into the Royal Navy Type 45 Destroyer
Authors: McCarthy Steven J. , Scott Ian
Published: July 2014

The WR-21 gas turbine engine will be employed by the Royal Navy and potentially by the United States and French Navies in their future Integrated Full Electric Powered Surface Combatants. The WR-21 is an advanced cycle gas turbine that will not only meet the high power generator prime mover requirements of these ships but also offer an efficient cruise generator engine in one power dense package. The engine gives ship designers the freedom to procure, install and maintain one engine to power the vessel over its entire operating profile in place of the traditional two engine ‘cruise’ and ‘boost’ fit. Warship operators will also have a new freedom to configure the warship propulsion plant to return unprecedented Platform Life Cycle Cost reductions in peacetime while retaining operational capability in time of conflict.

The Royal Navy is the first user of the WR-21 Intercooled and Recuperated (ICR) gas turbine engine in its Type 45 Area Defense destroyer. The vessel is a 6000 tonne monohull, fitted with an integrated electric propulsion plant comprising two WR-21 Gas Turbine Alternators (GTAs), the prime mover side of which are capable of delivering 25 MW (ISO) and the Alternator side of which is rated at 21.6 MWe (0.9 pf lagging), 4.16KVA. These GTAs in combination with a pair of diesel generators rated at around 2 MWe (0.9 pf lagging) will provide electrical power to two 20 MWe (0.9 pf lagging) 4.16 KVA electric propulsion motors and to the ship’s non propulsion consumer electrical distribution system. Any combination of generator set can provide any consumer with electrical power.

This flexibility of propulsion plant configuration will demand a step change in operating culture if its ultimate benefits are to be truly harnessed. Every part of warship propulsion and gas turbine engine operating philosophy must be examined to check its relevance in the modern machinery outfit. The engines themselves must be scrutinized to ensure that they can fulfill the requirements of true ship generation machinery and are not regarded as ‘propulsion generators’. In a Warship that has only four sources of electrical power the principles of survivability and prime mover independence are fundamental.
Selecting and Developing Advanced Alloys for Creep-Resistance for Microturbine Recuperator Applications
Authors: Maziasz Philip J. , Swindeman Robert W.
Published: July 2014

Recuperators are considered essential hardware to achieve the efficiencies desired for advanced microturbines. Compact recuperator technologies, including primary surface, plate and fin, and spiral, all require thin section materials that have high-temperature strength and corrosion resistance up to 750°C or above, and yet remain as low-cost as possible. The effects of processing and microstructure on creep-rupture resistance at 750°C and 100 MPa were determined for a range of austenitic stainless alloys made into 0.1 mm foils. Two groups of alloys were identified with regard to improved creep-resistance relative to type 347 stainless steel. Alloys with better creep-rupture resistance included alloys 120, 230, modified 803 and thermie-alloy, while alloy 214 and 625 exhibited much better creep strength. Alloys 120 and modified 803 appeared to have the most cost-effective improvements in creep-strength relative to type 347 stainless steel, and should be attractive for advanced microturbine recuperator applications.
Instrumenting and Acquiring Data for the WR21 Gas Turbine Development Programme
Authors: Bridgeman Grant , Uawithya Chai , Crance Côme
Published: July 2014

The development of the WR-21 Intercooled / Recuperated gas turbine started in 1991 and is now well advanced, having successfully completed ten engine tests at the Admiralty Test House (ATH) DERA Pyestock, NSWC Philadelphia and now having commenced endurance running at DCN, Indret.

The WR21 is the next generation of gas turbine prime mover, providing a significant annual fuel saving over the current marine propulsion gas turbines. Based on the RB211 family of commercial aero engines, the components are modified to incorporate an intercooler and recuperator into the simple cycle engine arrangement, improving the engine power and specific fuel consumption respectively.

The paper briefly outlines the engine tests of the WR21 development programme, and describes the instrumentation, data acquisition and processing systems that have been developed by Rolls Royce and the three difference test facilities to meet the varying demands of such gas turbine testing. The paper discusses the high levels of instrumentation used, its reliability and accuracy, the DAS architecture and the methods used to handle and process the data.
The Operating Experience of the Next Generation M501G/M701G Gas Turbine
Authors: Tsukuda Y. , Akita E. , Arimura H. , Tomita Y. , Kuwabara M. , Koga T.
Published: July 2014

The combined cycle power plant is recognized as one of the best thermal power plant for its high efficiency and cleanliness. As the main component of the combined cycle power plant, the gas turbine is the key for improvement of the combined cycle power plant.

The next generation G class gas turbine, with turbine inlet gas temperature in 1,500°C range has been developed by Mitsubishi Heavy Industries, Ltd. (MHI). Many advanced technologies; a high efficiency compressor, a steam cooled low NOx combustor, a high temperature and high efficiency turbine, etc., are employed to achieve high combined cycle performance. Actually, MHI has been accumulating the operating experiences of M501G (60Hz machine) a combined cycle verification plant in MHI Takasago, Japan, and achieving the high performance and reliability. Also, M701G (50Hz machine) has been accumulating the operating experience in Higashi Niigata Thermal Power Station of Tohoku Electric Power Co., Inc. in Japan.

This paper describes the technical features of M501G/M701G, and up-to-date operating status of the combined cycle power plant in MHI Takasago, Japan.
501F/M701F Gas Turbine Uprating
Authors: Akita E. , Arimura H. , Tomita Y. , Kuwabara M. , Tsukagoshi K.
Published: July 2014

The share of the gas turbine combined cycle plants tends to increase rapidly in the world of power generation. Under the circumstances, MHI is developing the several kinds of gas turbine to meet each customer’s needs.

The ‘F’ series’ engine, which has a firing temperature of 1350–1400 degree C, is predominant in the current market, and the reliability improvement is constantly performed. As a result, the operational hours of 50,000, and the combined cycle efficiency of 55–57% (LHV) is achieved for F-series combined cycle.

During the operating experience, any events occurred in field operation is solved. Also, countermeasure was implemented on every machine. Furthermore, robust design improvement is introduced, and commercial operation of the design achieved higher reliability and availability.

In this paper, the operating experiences, design improvements and the F series gas turbine uprating program are introduced.
A Comparison of Different Gas Turbine Concepts Using Biomass Fuel
Authors: Ferreira Sandro B. , Pilidis Pericles , Nascimento Marco A. R.
Published: July 2014

This paper aims to assess the performance of the Externally Fired Gas Turbine cycle (EFGT) and a variant, ICEFGT (InterCooled Externally Fired Gas Turbine), and Biomass Integrated Gasification Intercooled Recuperated cycle (BIG/ICR), all using biomass as fuel – solid in the EFGT cases and gasified in the BIG/ICR cycle. The results are compared with the performance of a Biomass Integrated Gasification Gas Turbine (BIG/GT), as a representative of the most common use of biomass in gas turbine cycles.

The energy and exergy analysis detailed here shows that if the challenges of the design and construction of the heat exchanger can be met, the externally fired cycles show great promise.
Model Identification of a Rotor With Magnetic Bearings
Authors: Vázquez José A. , Maslen Eric H. , Ahn Hyeong-Joon , Han Dong-Chul
Published: July 2014

The experimental identification of a long flexible rotor with three magnetic bearing journals is presented. Frequency response functions (FRFs) are measured between the magnetic bearing journals and the sensor locations while the rotor is suspended horizontally with piano wire. These FRFs are compared with the responses of a rotor model and a reconciliation process is used to reduce the discrepancies between the model and the measured data. In this identification, the wire and the fit of the magnetic bearing journals are identified as the sources of model error. As a result of the reconciliation process, equivalent dynamic stiffness are calculated for the piano wire and the fit of the magnetic bearing journals. Several significant numeral issues that were encountered during the process are discussed and solutions to some of these problems are presented.
Development and Implementation of Repair Processes for Refurbishment of W501F, Row 1 Turbine Blades
Authors: Curtis Richard , Miglietti Warren , Pelle Michael
Published: July 2014

In recent years, orders for new land-based gas turbines have skyrocketed, as the planning, construction and commissioning of new power plants based on combined-cycle technology advances at an unprecedented pace. It is estimated that 65–70% of these new equipment orders is for high-efficiency, advanced “F”, “G” or “H” class machines. The W501F/FC/FD gas turbine, an “F” class machine currently rated at 186.5 MW (simple cycle basis), has entered service in significant numbers. It is therefore of prime interest to owners/operators of this gas turbine to have sound component refurbishment capabilities available to support maintenance requirements. Processes to refurbish the Row 1 turbine blade, arguably the highest “frequency of replacement” component in the combustion and hot sections of the turbine, were recently developed. Procedures developed include removal of brazed tip plates, coating removal, rejuvenation heat treatment, full tip replacement utilizing electron beam (EB) and automated micro-plasma transferred arc (PTA), joining methods, proprietary platform crack repair and re-coating.

This paper describes repair procedure development and implementation for each stage of the process, and documents the metallurgical and mechanical characteristics of the repaired regions of the component.
Experimental Evaluation of a High-Gain Control for Compressor Surge Suppression
Authors: Blanchini Franco , Giannattasio Pietro , Micheli Diego , Pinamonti Piero
Published: July 2014

The present paper considers the suppression of surge instability in compression systems by means of active control strategies based on a high-gain approach. A proper sensor-actuator pair and a proportional controller are selected which, in theory, guarantee system stabilization in any operating condition for a sufficiently high value of the gain. Furthermore, an adaptive control strategy is introduced which allows the system to automatically detect a suitable value of the gain needed for stabilization, without requiring any knowledge of the compressor and plant characteristics. The control device is employed to suppress surge in an industrial compression system based on a four-stage centrifugal blower. An extensive experimental investigation has been performed in order to test the control effectiveness in various operating points on the stalled branch of the compressor characteristic and at different compressor speeds. On one hand the experimental results confirm the good performance of the proposed control strategy, on the other they show some inherent difficulties in stabilizing the system at high compressor speeds due to the measurement disturbances and to the limited operation speed of the actuator.
Evaluation and Comparison of Different Blade Cooling Solutions to Improve Cooling Efficiency and Gas Turbine Performances
Authors: Facchini Bruno , Innocenti Luca , Carnevale Ennio
Published: July 2014

The performance increase for Heavy Duty (HD) gas turbines requires very high R&D efforts to improve life and reliability of the hot components. In fact the maximum temperature increase is the most important factor for the HD gas turbines development. Blade cooling of hottest and most loaded turbine stages becomes a fundamental key for R&D process in gas turbine design. Several innovations have been realised in last years about blade cooling and many industrial manufacturers have recently proposed new coolants, like steam or water. In this paper a detailed comparison among different cooling systems and coolants is proposed. Therefore performances of the most important HD gas turbine models are predicted and applications of the various cooling solutions are evaluated. An advanced cooling scheme based on air cooling closed loop is also studied. The simulations have been made from the point of view of blade cooling design and of global plant performances prediction. Interesting results have been obtained to confirm the present trend of R&D of HD gas turbines. Finally a wide comparison between different cooling solutions for several gas turbine models is presented.
Assessment of Ceramic and Metal Media Filters in Advanced Power Systems
Authors: Alvin M. A.
Published: July 2014

Advanced, coal- and biomass-based gas turbine power generation technologies (IGCC, PFBC, PCFBC, HIPPS) are currently under development and demonstration. Efforts at the Siemens Westinghouse Power Corporation (SWPC) have been focused on the development and commercialization of hot gas filter systems as an enabling technology for power generation. As part of the commercialization effort, SWPC has been actively involved in the development of advanced filter materials and component configuration, has participated in numerous surveillance programs characterizing the material properties and microstructure of field tested filter elements, and has undertaken an extended accelerated filter life testing program. This paper reviews SWPC’s material and component assessment efforts, identifying the performance, stability, and life of porous oxide- and nonoxide-based ceramic, as well as metal and intermetallic filters used in advanced, high temperature, coal combustion systems.
Equivalent Availability Measurement for Combined-Cycle Power Plants: A New Approach
Authors: Lampert Dieter , Steele Robert F. , Rosenfelder Markus , DellaVilla Salvatore
Published: July 2014

The Equivalent Availability Factor (EAF) is the most important RAM characteristic in statistics for benchmarks and guarantees for power plants. It represents an energy ratio of the amount available in a period and the theoretical maximum. Representing the impact of scheduled and forced outages of components along with any deratings, a large number of parameters are involved from design, operation to the environment.

In 1993, ABB and SPS commenced a cooperation on the fields of data procurement and recording.

ABB brought large experience as a power plant supplier, SPS its competence as the leading firm specialized on RAM data service for the power industry worldwide.

In May 2000 ALSTOM affiliated the whole power generation division of ABB.

ALSTOM and SPS agreed to complete their periodic reports on time based reliability and availability data with EAF data. As the available energy must be calculated from the attributes of its components — in contrast to the effective produced energy that can be measured — the question of accuracy arises. Starting from the definition formula set as standard by ISO 3977/9 (former ANSI/IEEE 762), different methods have been considered to find the most suitable approach. The accuracy of comparisons of plants of different designs and operation modes and the ability to interpret the results is a measure for the suitability of the model chosen. Finally, some recommendations to handle and apply the EAF in the power plant business are given.
A Review of Purge Air Designs for Aeroengine Based Optical Pyrometers
Authors: Kerr Clive I. , Ivey Paul C.
Published: July 2014

With the advent of “power by the hour” type agreements within the civil aeroengine market, the application of engine monitoring system data has reached the level of strategic use for informed decision making in not only the aftermarket but increasingly in the contract negotiation stage. One of the key cost drivers in these dollar-per-hour contracts for the OEMs to analyze is the life and maintenance requirements of the turbine blades leading ultimately to blade life management. Such life management of key components is of critical importance to ensure that the economic and technical risks to both service provider and customer are minimized.

The optical pyrometer, through providing a direct temperature measurement of the turbine blades, is a primary input for providing a more realistic assessment of the component’s operating history associated with the use of life usage/remaining algorithms. However, the greatest concern with the in-service use of pyrometry is the issue of fouling since the pyrometer’s lens is exposed to the turbine environment. The level of optical contamination is usually minimized by introducing purge air, bled from the compressor, down the sight tube to prevent both the build-up of contaminants on the exposed system optics and particles in the gas stream from coming in contact with the lens. This paper provides a review of purge air designs and the key methodologies for engine designers to be acquainted with when seeking to integrate the use of optical pyrometry systems in new engine concepts.
U.S. Navy Gas Turbine Electric Start System
Authors: McAndrews Glenn , Worth Rick , Smith Robert
Published: July 2014

Today’s marine gas turbines are started using pneumatic or hydraulic systems. The weight, space, and reliability drawbacks of these systems is well known to ship systems designers who increasingly look to new technology for better solutions. It is not surprising then that the push towards an all-electric ship platform would eventually prompt the development of a suitable electric motor to replace fluid based systems. Lately, research efforts sponsored by the U.S. Navy have intensified to do exactly that. This paper will discuss the background and current efforts to introduce an electric start system for future marine gas turbines.
Gas Turbine Intake Systems-High Velocity Filtration for Marine Gas Turbine Installations
Authors: Mudge R. K. , Hiner S. D.
Published: July 2014

The Royal Navy (RN) has operated marinised industrial and aero-derivative propulsion gas turbines since the late 1940’s. In order to safeguard the gas turbines (principally from foreign object damage (FOD) and salt ingestion) the RN places a high degree of importance on the gas turbine intake system, a principal element within which is the intake filtration equipment.

Since the introduction of marine gas turbines the RN have witnessed and participated in the development of intake filtration systems from knitmesh filters to highly efficient 3 stage (vane- coalescer-vane) separators (spray eliminators).

The requirements for RN gas turbine intake systems are described in Naval Engineering Standard (NES 312), and have been brought about by long standing operational experience of these systems and commercial best practice.

This paper will briefly outline the RN design criteria for gas turbine intake systems and how this has been modified by field experience. It will then go on to look at intake separators, giving their design criteria and describe from inception, a study into the possible adoption of next generation high velocity spray eliminators describing initial specification, the product design process and development testing. The potential benefits afforded by such a high velocity system will also be discussed.

In addition the paper will describe the initial fit of a trial unit onto HMS Coventry, for back to back testing with a unit of conventional design.

It is intended to present Part 2 of this paper at ASME 2002 Amsterdam, which will contain a précis of the design, presentation of the data from the sea trial and the results and conclusions from the engine inspections, including an assessment by Rolls Royce the engine Design Authority.

At this time the sutability of the equipment for the intakes of the WR21 will be considered.
On the Prediction of Secondary Flows in a U-Bend
Authors: Song B. , Amano R. S.
Published: July 2014

The secondary flows inside a sharp U-bend are numerically studied by using non-linear low Reynolds number (low-Re) k – ω model in which the cubic terms are included to represent the effects of extra strain-rates such as streamline curvature and three-dimensionality on both turbulence normal and turbulence shear stresses. The finite volume difference method incorporated with the higher-order bounded interpolation scheme has been employed in the present study. For the purpose of comparison, the predictions with the Launder-Sharma model (the linear low-Re k – ε model) are also given. The present results reveal that non-linear low-Re k – ω model and linear model produce the quite different secondary flow patterns. It is shown that the present non-linear model produces satisfactory predictions of the flow development inside the sharp U-bend comparing with linear Launder-Sharma model.
Economic and Technical Challenges Facing Large-Scale Gas Turbine Projects due to Environmental Requirements for Extremely Low Emissions
Authors: Zachary Justin
Published: July 2014

Since 1998, the United States has experienced a tremendous increase in power generation projects using gas turbine technology. By burning natural gas as the primary fuel and low sulfur oil as a back-up fuel, gas turbines are the cleanest form of fossil power generation.
Rig and Gas Turbine Engine Testing of MI-CMC Combustor and Shroud Components
Authors: Corman Gregory , Dean Anthony , Brabetz Stephen , McManus Keith , Brun Milivoj , Meschter Peter , Luthra Krishan , Wang HongYu , Orenstein Robert , Schroder Mark , Martin Devin , De Stefano Roberta , Tognarelli Leonardo
Published: July 2014

GE is continuing work on the development of Melt-Infiltrated Ceramic Matrix Composites (MI-CMC) for use in industrial gas turbine engine components. Long-term environmental degradation of test samples under realistic engine conditions is being determined using a unique high-pressure combustion rig apparatus. Rig testing is also being used to evaluate an F-class 1st stage shroud system incorporating an MI-CMC inner shroud component. While large, advanced engines, such as the F and H classes, offer the greatest benefits for using MI-CMC components, initial engine tests have been done using a GE-2 (2MW) machine to reduce costs and risk. Long term (1000 hours) engine testing results for single piece GE-2 shrouds are also described.
The Dynamics of a Cracked Rotor With an Active Magnetic Bearing
Authors: Zhu Changsheng , Robb David A. , Ewins David J.
Published: July 2014

The dynamic characteristics of a cracked rotor with an active magnetic bearing (AMB) are theoretically analyzed in this paper. The effects of using optimal controller parameters on the dynamic characteristics of the cracked rotor and the effect of the crack on the stability of the active control system are discussed. It is shown that the dynamic characteristics of the cracked rotor with AMBs are clearly more complex than that of the traditional cracked rotor system. Adaptive control with AMBs may hide the fault characteristics of the cracked rotor, rather than helping to diagnose a crack; this will depend on the controller strategy used. It is very difficult to detect a crack in the AMB-rotor system when the vibration of the rotor system is fully controlled. Only the super-harmonic components of 2X and 3X revolution in the sub-critical speed region can be used as a index to detect a crack in the rotor–AMB system. If the effect of the crack is not considered in designing the controller, then the AMB-rotor system will lose its stability in some cases when cracks appear.
Three-Dimensional Unsteady Flow Field due to Rotor-Stator Interaction in the Tip Region of an Axial Compressor Stator Passage
Authors: Ma Hongwei , Jiang Haokang , Zhang Qingguo
Published: July 2014

This paper reports an experimental study of the three-dimensional unsteady flow field due to rotor-stator interaction in the tip region of an axial compressor stator passage. The measurements were conducted on a low-speed large-scale axial compressor using a 3-component Laser Doppler Velocimetry. Both experimental method and measurement techniques are presented in details. The measurement results indicate that the rotor tip leakage vortex and the rotor wake periodically pass through the tip region of a stator passage, resulting in periodical flow blockages and fluctuations in the stator passage. In the meantime, the wake is catching up with the last rotor leakage vortex. The interaction and the flow mixing between the vortex and the wake occur in a stator passage, leading to more substantial fluctuations in the flow field. The rotor lip leakage vortex has a stronger influence on the downstream endwall flow than the rotor wake. The low-energy fluids from the upstream tend to accumulate toward the pressure surface of a stator blade. The separation flow near the suction surface is found in the rear of a stator passage. The interaction and the flow mixing are observed among the low-energy fluids from the upstream and the separation flow.
Autophagy Protects the Tired, the Poor, the Huddled (β Cell) Masses
Authors: Beaven Simon W.
Published: July 2014

Autophagy is needed to clear the toxic amyloid deposits that destroy pancreatic β cells and lead to diabetes.
A Pillar of Hope for New Multiple Sclerosis Therapeutics
Authors: Tesar Paul J.
Published: July 2014

Engineered micropillar arrays enable high-throughput screening for drugs that promote remyelination in disorders such as multiple sclerosis.
Antigen Export during Liver Infection of the Malaria Parasite Augments Protective Immunity
Authors: Montagna Georgina N. , Beigier-Bompadre Macarena , Becker Martina , Kroczek Richard A. , Kaufmann Stefan H. E. , Matuschewski Kai
Published: July 2014

Protective immunity against preerythrocytic malaria parasite infection is difficult to achieve. IntracellularPlasmodiumparasites likely minimize antigen presentation by surface-expressed major histocompatibility complex class I (MHC-I) molecules on infected cells, yet they actively remodel their host cells by export of parasite factors. Whether exported liver-stage proteins constitute better candidates for MHC-I antigen presentation to CD8+T lymphocytes remains unknown. Here, we systematically characterized the contribution of protein export to the magnitude of antigen-specific T-cell responses againstPlasmodium bergheiliver-stage parasites in C57BL/6 mice. We generated transgenic sporozoites that secrete a truncated ovalbumin (OVA) surrogate antigen only in the presence of an amino-terminal protein export element. Immunization with live attenuated transgenic sporozoites revealed that antigen export was not critical for CD8+T-cell priming but enhanced CD8+T-cell proliferation in the liver. Upon transfer of antigen-specific CD8+T cells, liver-stage parasites secreting the target protein were eliminated more efficiently. We conclude thatPlasmodiumparasites strictly control protein export during liver infection to minimize immune recognition. Strategies that enhance the discharge of parasite proteins into infected hepatocytes could improve the efficacy of candidate preerythrocytic malaria vaccines.

IMPORTANCEVaccine development againstPlasmodiumparasites remains a priority in malaria research. The most advanced malaria subunit vaccine candidates containPlasmodiumsurface proteins with important roles for parasite vital functions. A fundamental question is whether recognition by effector CD8+T cells is restricted to sporozoite surface antigens or extends to parasite proteins that are synthesized during the extensive parasite expansion phase in the liver. Using a surrogate model antigen, we found that a cytoplasmic antigen is able to induce robust protective CD8+T-cell responses, but protein export further enhances immunogenicity and protection. Our results show that a cytoplasmic localization does not exclude a protein’s candidacy for malaria subunit vaccines and that protein secretion can enhance protective immunity.
Temporal and other factors that influence the time doctors take to prescribe using an electronic prescribing system
Authors: Coleman Jamie J , Hodson James , Thomas Sarah K , Brooks Hannah L , Ferner Robin E
Published: July 2014

Background A computerized physician order entry (CPOE) system with embedded clinical decision support can reduce medication errors in hospitals, but might increase the time taken to generate orders.

Aims We aimed to quantify the effects of temporal (month, day of week, hour of shift) and other factors (grade of doctor, prior experience with the system, alert characteristics, and shift type) on the time taken to generate a prescription order.

Setting A large university teaching hospital using a locally developed CPOE system with an extensive audit database.

Design We retrospectively analyzed prescription orders from the audit database between August 2011 and July 2012.

Results The geometric mean time taken to generate a prescription order within the CPOE system was 11.75 s (95% CI 11.72 to 11.78). Time to prescribe was most affected by the display of high-level (24.59 s (24.43 to 24.76); p<0.001) or previously unseen (18.87 s (18.78 to 18.96); p<0.001) alerts. Prescribers took significantly less time at weekends (11.29 s (11.23 to 11.35)) than on weekdays (11.88 s (11.84 to 11.91); p<0.001), in the first (11.25 s (11.16 to 11.34); p<0.001) and final (11.56 s (11.47 to 11.66); p<0.001) hour of their shifts, and after the first month of using the system.

Conclusions The display of alerts, prescribing experience, system familiarity, and environment all affect the time taken to generate a prescription order. Our study reinforces the need for appropriate alerts to be presented to individuals at an appropriate place in the workflow, in order to improve prescribing efficiency.
Solitary bone cyst of the mandible: a case report and brief review of literature
Authors: Madiraju GunaShekhar , Yallamraju SuryanarayanaRaju , Rajendran Vijayakumar , SrinivasaRao Kolasani
Published: July 2014

A solitary bone cyst is a non-neoplastic osseous lesion comprising 1% of all the cysts affecting the jaws. They are generally asymptomatic, usually detected incidentally during routine radiological assessment and are less common in the mandibular anterior region. This article presents a well-documented case involving a solitary bone cyst affecting the mandibular symphysis in a 12-year-old boy with no history of previous trauma. Simple curettage of the bone cavity resulted in the resolution of the lesion with progressive osseous regeneration. No evidence of recurrence was noted 2 years after the treatment.
De Garengeot's hernia: our experience of three cases and literature review
Authors: Akbari Khalid , Wood Claire , Hammad Ahmed , Middleton Simon
Published: July 2014

Groin hernia is a common surgical presentation and nearly half of the femoral hernias present acutely with strangulation. The hernia sac usually contains omentum or small bowel. Rarely, the appendix can herniate into the femoral canal. De Garengeot's hernia is the term used to describe the presence of appendicitis in the femoral hernia. Hernia explorations are performed by surgical trainees and encountering a De Garengeot's hernia can be challenging to manage. We report our experience of three cases of this rare entity and a literature review to improve our understanding for optimum management.
Cerebral venous thrombosis presenting with subdural haematoma as first presentation for systemic lupus erythematosus with negative antiphospholipid antibodies
Authors: Alboudi Ayman , Sarathchandran Pournamy , Alrukn Suhail , Al Madani Abubaker
Published: July 2014

We report the case of a 30-year-old woman, without any previous comorbidities presenting with acute onset headache, altered sensorium and unsteadiness of gait. Neurological evaluation revealed a drowsy patient with papilloedema, bilateral lateral rectus palsy, generalised hyper-reflexia and up going plantar responses. Urgent imaging performed showed extensive cortical venous sinus thrombosis. Workup for secondary causes of cortical venous sinus thrombosis revealed very high titres of antinuclear antibody and anti-dsDNA, but negative antiphospholipid antibodies (APLA). In hospital she started developing other complications of systemic lupus erythematosus (SLE). Urine evaluation revealed proteinuria and granular casts suggestive of glomerulonephritis. Cardiac evaluation revealed moderate pericardial effusion. We have discussed neurolupus as initial presentation of SLE and the rare occurrence of major neurovascular complications without secondary APLA syndrome.
The relationship between labour market categories and alcohol use trajectories in midlife
Authors: Colell Esther , Bell Steven , Britton Annie
Published: July 2014

Background and aims

Studies on the role of labour market position and change in alcohol use during midlife are scarce and their results are inconclusive mainly due to their failure to define comprehensive and distinct labour market groups and the short periods of time studied. In this study we used different activity categories for men and women to examine alcohol use trajectories in midlife covering a period of 17 years.

Methods

Using data from four sweeps of the National Child Development Study covering ages 33–50 (N=9960), we used multilevel growth models to study the association between labour market categories and longitudinal changes in weekly units of alcohol consumed.

Results

In the reference group of full-time employed men alcohol trajectory decreased over the follow-up period (β=−0.14; 95% CI −0.18 to −0.11) while in the reference group of employed women it increased (β=0.06; 95% CI 0.04 to 0.08). Men and women who were ‘mainly sick’ had significantly steeper declines in their alcohol consumption trajectory. Women who became employed after being homemakers had the steepest increase in alcohol use (β=0.05; 95% CI 0.01 to 0.09).

Conclusions

Being employed is a strong determinant of alcohol use for men and women in midlife, making the workplace a good target for health promotion programmes and policies aimed at reducing alcohol use. Caution is needed when interpreting the health effects of alcohol consumption as low alcohol users may have previously been heavy drinkers.
Remote sensing of the environment with small unmanned aircraft systems (UASs), part 1: a review of progress and challenges
Authors: Whitehead Ken , Hugenholtz Chris H.
Published: July 2014

The recent development and proliferation of unmanned aircraft systems (UASs) has made it possible to examine environmental processes and changes occurring at spatial and temporal scales that would be difficult or impossible to detect using conventional remote sensing platforms. This review article highlights new developments in UAS-based remote sensing, focusing mainly on small UASs (<25 kg). Because this class is generally less expensive and more versatile than larger systems the use of small UASs for civil, commercial, and scientific applications is expected to expand considerably in the future. To highlight different environmental applications, we provide an overview of recent progress in remote sensing with small UASs, including photogrammetry, multispectral and hyperspectral imaging, thermal, and synthetic aperture radar and LiDAR. We also draw on the literature and our own research experience to identify some key research challenges, including limitations of the current generation of platforms and sensors, and the development of optimal methodologies for processing and analysis. While much of the potential of small UASs for remote sensing remains to be realised, it is likely that the next few years will see such systems being used to provide data for an ever-increasing range of environmental applications.
Chaotic Oscillations of Solutions of the Klein–Gordon Equation Due to Imbalance of Distributed and Boundary Energy Flows
Authors: Chen Goong , Sun Bo , Huang Tingwen
Published: July 2014

Chaos in physical systems governed by nonlinear PDEs have been amply observed and reported. However, rigorous proofs for their occurrences are challenging. In particular, for a second order PDE of hyperbolic type with a van der Pol cubic nonlinearity in one of the boundary conditions and a spatially distributed antidamping term in a linear governing equation, no proof for the onset of chaos was available even though chaos was expected to occur when the antidamping term becomes sufficiently strong. In this paper, we use an operator-factoring technique together with the analogy with the one-dimensional wave equation to prove that for the Klein–Gordon equation chaos occurs for a class of equations and boundary conditions when system parameters enter a certain regime. Chaotic and nonchaotic profiles of solutions are illustrated by computer graphics.
Low-Dimensional Discrete Kuramoto Model: Hierarchy of Multifrequency Quasiperiodicity Regimes
Authors: Kuznetsov Alexander P. , Sedova Yuliya V.
Published: July 2014

The dynamics of a low-dimensional ensemble consisting of a network of five discrete phase oscillators is considered. A two-parameter synchronization picture, which appears instead of the Arnol'd tongues with an increase of the system dimension, is discussed. An appearance of the Arnol'd resonance web is detected on the "frequency–coupling" parameter plane. The cases of attractive and repulsive interactions are discussed.
Normal Forms for Codimension One Planar Piecewise Smooth Vector Fields
Authors: de Carvalho Tiago , Tonon Durval José
Published: July 2014

In this paper, we are dealing with piecewise smooth vector fields in a 2D-manifold. In such a scenario, the main goal of this paper is to exhibit the homeomorphism that gives the topological equivalence between a codimension one piecewise smooth vector field and the respective C0-normal form.
Global Regularization of a Restricted Four-Body Problem
Authors: Alvarez-Ramírez Martha , Delgado Joaquín , Vidal Claudio
Published: July 2014

In the n-body problem, a collision singularity occurs when the position of two or more bodies coincide. By understanding the dynamics of collision motion in the regularized setting, a better understanding of the dynamics of near-collision motion is achieved. In this paper, we show that any double collision of the planar equilateral restricted four-body problem can be regularized by using a Birkhoff-type transformation. This transformation has the important property to provide a simultaneous regularization of three singularities due to binary collision.

We present some ejection–collision orbits after the regularization of the restricted four-body problem (RFBP) with equal masses, which were obtained by numerical integration.
Extended Kalman Filter-Based Codec for Chaotic Communication Systems
Authors: Lin Jia-Hong , Lin Wei-Song
Published: July 2014

Two methods are presented to encode and decode messages accurately with an expanded matrix representation of linear multivariable systems in which parameters are used to describe three-port chaotic secure communication networks. The matrix representation includes an optimal extended Kalman filter (EKF)-based observer, which is linear with time. The optimal linearization technique is used to find the exact linear models of the chaotic system at operating states of interest. Subsequently, the EKF algorithm is used to estimate the parameters and states in which a message is embedded. Using the EKF with the optimal linear model, the message can be adequately recovered at the receiver. However, the bit error rate is insufficiently small; therefore, presynchronizations and the carrier-digitalized sources are used to reduce the error rate to obtain robust communications. Numerical examples and simulation results demonstrate the effectiveness of the proposed methodology.
Periodic Solutions for a Predator–Prey Model with Periodic Harvesting Rate
Authors: Tang Yilei , Xiao Dongmei
Published: July 2014

In the paper, we study the existence of periodic solutions in an invariant manifold for a predator–prey model with periodic harvesting rate. Without harvesting, the predator–prey system has a positive equilibrium of center type, which undergoes Hopf bifurcation. Under the periodic harvesting, we first reduce this predator–prey system to a complex normal form. Then, we define the Poincaré mapping of this system by using the polar coordinates, and prove that there exists an integral manifold and periodic solution with the period of the harvesting rate. An example is provided to illustrate the result.
Delayed Bifurcations to Repetitive Spiking and Classification of Delay-Induced Bursting
Authors: Han Xiujing , Bi Qinsheng , Zhang Chun , Yu Yue
Published: July 2014

Three new routes to repetitive spiking, i.e. the delayed transcritical bifurcation, the delayed supercritical pitchfork bifurcation and the delayed subcritical pitchfork bifurcation, are revealed in this paper. We use bifurcation theory to classify bursting patterns related to three such delayed bifurcations. Then many new bursting patterns are obtained, including 24 new bursting patterns of point-point type, 27 new bursting patterns of point-cycle type and three new bursting patterns of point-torus type. Our study suggests that the classification of bursting remains to be further explored, since many new bursting patterns may be obtained based on new routes to repetitive spiking, even though we just consider codimension-1 bifurcations.
Design and Topological Analysis of Complex Networks with Optimal Controllability
Authors: Yang Cuili , Tang Wallace K. S.
Published: July 2014

In this paper, we aim to identify a directed complex network with optimal controllability, for which pinning control is to be applied. Since the controllability of a network can be reflected by the smallest nonzero eigenvalue of a matrix related to its topology, an optimal network design problem is formulated based on the maximization of this eigenvalue. To better consider the practical reality, constraints on node degree sequence are specified. Based on the derived bounds of the eigenvalue, an effective rewiring scheme is designed and solutions close to or equal to the upper bound are obtained. Finally, the relationship between network characteristics and controllability is studied. Through complexity analysis, it is concluded that the network with high controllability should possess two properties, i.e. nodes with high out-degree for pinning and other nodes with uniform degree distribution.