bluuebunny/crossref_metadata_2025 huggingface dataset:
Engine Cycle Selection and Propulsion System Integration for Future High Performance Fighter Aircraft
Authors: Lind G. W. , Protopapas J.
Published: April 2015

The selection and optimization of propulsion systems can be a costly and time-consuming process, especially when there are diverse performance requirements placed on the overall weapon system. Computerized procedures have been developed within the Grumman Propulsion Department to mechanize this capability and yet maintain the man-m-the-loop for full visibility during the evaluation of a candidate design concept. The system permits low cost, rapid, multidiscipline. interactive engine cycle selection and propulsion system integration to be effectively performed early in the preliminary design process of a high performance fighter aircraft. For example, the computer running time required to select a point design within a matrix of design variables and performance constraints has been reduced by 85 percent over previous techniques. This paper describes these propulsion evaluation procedures and cites a specific example of their application to the analysis of an advanced interceptor requirement.
Status Report of the Turbofan Engine Development Program in Japan
Authors: Matsuki M. , Torisaki T. , Miyazawa K. , Itoh M.
Published: April 2015

A National Research and Development Program of high bypass ratio turbofan engines has been in process in Japan since 1971. Target performance characteristics of the first-phase 5-ton thrust class engines have been attained, and development of the second-phase engines has been started in 1976. This paper reviews the status of the program, discusses some engineering progress attained, and presents an outline of the second-phase program and engines.
Small Regenerative Gas Turbine Design and Development at MTU
Authors: Heilmann W. , Hagemeister K.
Published: April 2015

This paper is a report on the design and development of a small regenerative gas turbine and on the component technology involved in this development. It is shown — on the basis of test results — that the gas turbine is a potential competitor of the Diesel engine for powering trucks, if the economy of the gas turbine can be improved. Future development work must therefore be aimed at improving the efficiency of the individual components and at applying ceramic materials in the hot parts of the engine.
The Design of Turbomachinery for the Gas Turbine (Direct Cycle) High Temperature Gas Cooled Reactor Power Plant
Authors: Adams R. G. , Boenig F. H.
Published: April 2015

The Gas Turbine HTGR, or “Direct Cycle” High-Temperature Gas-Cooled, Reactor power plant, uses a closed-cycle gas turbine directly in the primary coolant circuit of a helium-cooled high-temperature nuclear reactor. Previous papers have described configuration studies leading to the selection of reactor and power conversion loop layout, and the considerations affecting the design of the components of the power conversion loop. This paper discusses briefly the effects of the helium working fluid and the reactor cooling loop environment on the design requirements of the direct-cycle turbomachinery and describes the mechanical arrangement of a typical turbomachine for this application. The aerodynamic design is outlined, and the mechanical design is described in some detail, with particular emphasis on the bearings and seals for the turbomachine.
A New 10,000-Hp Gas Turbine Engine for Industrial Service
Authors: Pichel P. W.
Published: April 2015

This paper summarizes the scope and results to date of a program initiated in 1974 to develop a high-performance, simple-cycle, 10,000-hp engine for application in gas compressor, mechanical drive, and generator set packages. Design philosophy, a detailed description, and component and engine development testing are covered. Future plans for the development program up to the point of production availability in 1978 are also outlined.
A Study of an Advanced Automotive Radial Turbine: A Design Procedure Considering Rotor Loss Distributions and Exit Flow Patterns
Authors: Takizawa Masaaki , Sasaki Shoji , Mizumachi Nagao
Published: April 2015

This paper describes analytical and experimental investigations to develop advanced radial turbines for automotive use. The performance of turbines was estimated considering radial distributions of the rotor velocity coefficient. The results of this estimation suggested that an about 5 percent improvement in turbine efficiency could be expected by optimizing the rotor exit flow patterns. To confirm these concepts, two turbines were designed and investigated experimentally. The both turbines indicated the satisfactory performance resulting from the improved rotor velocity coefficients.
Static and Flyover Noise Measurements of an Inverted Profile Exhaust Jet
Authors: Burcham F. W. , Lasagna P. L. , Kurtenbach F. J.
Published: April 2015

Tests using a TF30 mixed flow afterburning turbofan engine in an F-111 airplane were conducted to study the noise characteristics of an inverted velocity profile jet. Full-authority digital engine control allowed the inverted profile jet to be compared to a uniform jet of equal thrust statically and in flight. An exhaust velocity survey showed that the ratio of the outer to inner stream velocities was 1.37; therefore, only small noise reductions were expected. At static conditions, the inverted profile jet was approximately 3 decibels quieter than the uniform jet at peak noise angles. During a flyover it was approximately 1 decibel quieter.
Life Cycle Cost as a Propulsion System Design Consideration
Authors: Curry C. E.
Published: April 2015

This paper deals with applying Life Cycle Cost (LCC) and Design To Cost (DTC) principles to aircraft engine programs. The dynamic driving elements of LCC are identified with an example of direct application to a deterministic computer model. This model was used as the principal tool to project operating and support costs for the XT701 turboshaft engine in conjunction with the U.S. Army Heavy Lift Helicopter Development that featured a specific DTC-related award fee in the contract. The overall methodology of LCC and DTC supported by the math model earned a Superior evaluation with an unprecedented 100 percent award fee for this kind of application. The customer audit, in support of the performance award, supports the conclusion that computer models can be used to enhance the LCC aspects of propulsion system development programs.
Investigating Combustion Turbine Burner Performance With Coal Derived Liquids Having High Fuel Bound Nitrogen
Authors: Pillsbury P. W. , Cohn A. , Mulik P. R. , Stein T. R.
Published: April 2015

The Electric Power Research Institute is conducting a program to develop combustion turbine burners for high-bound nitrogen, highly aromatic, low hydrogen/carbon ratio coal derived liquids. The problems of fueling standard units with these liquids are being determined, with special emphasis on environmental aspects. Small-scale and full-scale laboratory combustor tests are described. Results from earlier tests are surveyed, especially with regard to smoke production NOx emissions and flame radiation. A unique feature of the present program is the stress on developing surrogate petroleum-derived fuel to “stand-in” for scarce coal liquids during early development of the advanced burners needed to handle a broad range of coal liquids.
The Prospects for Lightweight Ship Propulsion Systems
Authors: Kuo S. C. , Horton T. L. O. , Shu H. T. , Seng W. R.
Published: April 2015

A comprehensive systems study was made to evaluate the technological and economic feasibility of utilizing open- and closed-cycle gas turbines for providing advanced lightweight propulsion power for future Navy ship applications. Extensive parametric analyses were made of the performance and weight characteristics for the propulsion engine cycles selected, and applicable turbomachinery technologies were reviewed to estimate their future advances expected. The payload capabilities and endurance limitations resulting from utilization of different propulsion systems in the 40,000 -to 300,000-shp range for selected ship types were identified.
The Use of Gas Turbine Laboratories in Teaching Engineering and Non-Engineering Students
Authors: Richard C. C. , Latham R. F.
Published: April 2015

The United States Navy has committed itself to gas turbine power systems for a number of its present-day ships. Although gas turbine theory and practice have long been a part of the curriculum at the U. S. Naval Academy, it recently has become essential to expand classroom and laboratory programs. The graduating naval officer, regardless of educational major, must have a background that familiarizes him not only with the theory of gas turbines, but with the actual running of such machinery. Special problems associated with applying gas turbines to shipboard conditions must be understood and appreciated. This paper traces the history of the use of gas turbine laboratories in supporting classroom work at the U. S. Naval Academy. Two levels of educational effort are addressed: (a) gas turbine theory and laboratory exercises for the engineering major, and (b) gas turbine theory and laboratory exercises for the non-engineering major. Programs for both classes of students are explained including sample laboratory exercises and typical results.
Design and Development of a Power Turbine for the Spey Gas Generator
Authors: Reed N. G. , Wilson J. M.
Published: April 2015

The engineering aspects of a new high efficiency 16,200-hp (12,080-MW) gas turbine using the Spey gas generator are presented. The history of the Spey and its evolution as an industrial gas generator are given. The design philosophy, aerodynamic features, and mechanical aspects of the new power turbine are discussed. Full-load laboratory test results of the new unit are reviewed. The first field installation, including the conversion of an existing natural gas pipeline unit from an Avon gas generator, is described. The first year of field operating experience is also summarized.
Dynamic Stall of an Airfoil With Leading Edge Bubble Separation Involving Time Dependent Re-Attachment
Authors: Tokel H. , Sisto F.
Published: April 2015

The dynamic stall of an airfoil with leading edge bubble separation is analyzed. The stall flutter of turbomachine blading may involve periodic growth and collapse of such a bubble. The mathematical model representing the physical problem is presented. A flat plate undergoing harmonic oscillations with time-dependent point of re-attachment is studied for the perturbed aerodynamic reactions and applications to the stall flutter problem.
Operating Experience With the Gas Turbine Powered LNG/Ethylene Carrier “LUCIAN”
Authors: Naesheim K. , Rowen W. I.
Published: April 2015

The GTV LUCIAN is a 29,000-cu m liquefied gas carrier designed, utilizing the Kvaerner-Moss tank system, as a world trader. The vessel is powered by a 20,000-hp heavy-duty marine gas turbine, equipped to burn a wide range of heavy residual fuels in combination with LNG cargo boil-off. Since entering commmercial service in June 1975, the LUCIAN has traveled almost 150,000 n.m., and accumulated approximately 9000 fired hours on the propulsion machinery. Virtually all of this service occurred using heavy residua fuels, with some operation in a dual-fuel mode with cargo boil-off, when LNG cargo was being carried. This paper briefly describes the vessel and her propulsion machinery, with particular emphasis on those features which are unique to this application. The operating experiences acquired during the last two years are then reviewed. Operating problems encountered with the propulsion machinery are discussed in depth, as are the solutions developed to resolve them.
Design of a Family of Packages for a 7500-kW Industrial Gas Turbine
Authors: Williamson D. , Fistere J.
Published: April 2015

When a new large gas turbine engine is developed for use in economically sensitive environments, it is necessary to make careful trade-off decisions on such potentially conflicting requirements as: ruggedness versus weight, high aerodynamic efficiency versus low first cost, efficient high firing temperatures versus air quality standards and long life, etc. Similarly, the equipment to be driven by the gas turbine must also be carefully selected and developed for optimum application. In addition to the above, it is the task of the package to integrate the primary machinery and all of its supporting systems into a single cohesive, product. Therefore, similar sound technical, functional, and economic evaluations must be made for fuel, lubricating, gas sealing, control systems, and the physical arrangement of the package itself. Sound application of the fundamental concepts of reliability, redundancy, and safety are essential to the successful operation of these systems, which must meet life criteria of 30,000 hr or more of continuous operation without major maintenance. All turbine systems are automatic and are frequently called upon to operate remotely in marine, desert, and arctic environments. The ability of such systems to respond to a variety of electronic load and speed signals predictably and accurately is essential to the acceptance of the gas turbine in industrial application. Efficient, effective, and reliable monitoring systems, which will sense essential operating parameters and act to protect the major equipment from catastrophic failure, must themselves be selected for reliability, accuracy, and endurance. The combination of all of the above forms the essence of design criteria for gas turbine packages.
Test Procedures for Establishing the Altitude Performance of Turbofan Engines to Validate Contractual Guarantees
Authors: Dean G. W.
Published: April 2015

The facilities at The National Gas Turbine Establishment for direct-connect tests on turbofans and turbojets at conditions simulating flight at altitude are briefly described. The measurements that have to be made to establish performance within the prescribed limits required for contractual guarantees are derived. Techniques are discussed for eliminating the effect of small, but significant, time-variant changes which occur in the quantities being measured due to unsteadiness in instrumentation, engine and test conditions. Methods evolved for ensuring continuing operation of the instrumentation and data gathering system at the required high level of accuracy are outlined. A standardized test procedure (Test Code) for establishing contract guarantee performance at NGTE is discussed with illustrative examples.
Nonlinear Digital Simulation and Minimum Fuel Control of a Jet Type Gas Turbine Power Generating Unit
Authors: Weiner D. , Aschner F. S. , Dayan J.
Published: April 2015

This paper discusses the digital nonlinear simulation of a twin-spool gas generator-free turbine power generating unit. The mathematical model derived is flexible and can be easily converted to suit any other gas turbine. Simulation results were verified by comparison to measured data. The model was applied to optimize a fuel control schedule by methods of Mathematical Programming, taking into account the constraints imposed by the protective control of the system.
A Study of Thermal Fatigue Life Prediction of Air-Cooled Turbine Blades
Authors: Maya T. , Katsumata I. , Itoh M.
Published: April 2015

One of the techniques for estimation of thermal fatigue life of air-cooled turbine blades is assured through coincidence between the results of experimental and analytical works. The actual turbine blades were tested on the test rig utilizing alternating hot and cold jet method under simulated operating conditions of the high-bypass ratio turbofan engine. Acoustic emission method is applied to detect the crack initiation of tested blades. The experimental data were analyzed statistically and the result was well close to the analytical value which was calculated using structural analysis program NASTRAN and universal slope relation.
The Effects of Smoke Suppressant and Corrosion Inhibiting Fuel Additives on the Particulate and Gaseous Emissions From a Utility Gas Turbine
Authors: Hersh S. , Hurley J. F. , Carr R. C.
Published: April 2015

The effects that three metallic-based smoke-suppressant additives and one corrosion-inhibiting additive have on the particulate and gas phase emissions (including polycyclic organic matter) from an electric utility gas turbine were examined using state-of-the-art sampling techniques and laboratory methods. Test results support the conclusion that the decrease in utility turbine exhaust plume opacity with additive injection rate is primarily due to a reduction in carbonaceous emission. Exhaust particle size distributions were found not to shift significantly with additive use for base load operation. No significant effects were seen in overall turbine output performance or gaseous emissions, including POM, with additive use. A slight trend of particulate sulfate increase and conversion of SO2 to SO3 with additive increase was indicated.
Requirements for Educational Gas Turbines
Authors: Saravanamuttoo H. I. H. , Skinner A.
Published: April 2015

Many university and college laboratories operate gas turbines which were installed about 15 years ago, and some thought must be given to eventual replacement. This paper reviews the requirements of gas turbines suitable for this market and compares the relative merits of single-shaft and free turbine units. It is suggested that a single-shaft unit with a load compressor has considerable merit with regard to operating flexibility, versatility, and performance, and design aspects of a suitable unit are discussed.
Status of the DOE/NASA Critical Gas Turbine R & T Project
Authors: Clark J. S.
Published: April 2015

The purpose of the DOE/NASA CRT (Critical Research and Technology) Project at the Lewis Research Center is to provide an R&T data base for utility gas turbine systems burning coal-derived fuels. Coal-derived fuels present difficult problems in combustion (because of the high organically-bound nitrogen in the fuel), and materials (because of the trace metal contaminant levels in the fuels, leading to corrosion and deposition in the turbine hot section). The combustion task includes (1) an effort to model the rich-lean combustion process, to predict NOx emissions; (2) a two-stage flame tube experiment to study the effects of combustion operating conditions and fuel properties on NOx conversion; and, (3) scaled combustor tests to evaluate the NOx-reduction potential of several staged-combustion concepts. The materials-corrosion resistance effort attacks the problem on three sides.
Survey of Integrated Gasification Combined Cycle Power Plant Performance Estimates
Authors: Larson J. W.
Published: April 2015

The idea of a combined cycle power plant integrated with a coal gasification process has attracted broad interest in recent years. This interest is based on unique attributes of this concept which include potentially low pollutant emissions, low heat rate and competitive economics as compared to conventional steam plants with stack gas scrubbing. Results from a survey of technical literature containing performance and economic predictions have been compiled for comparison and evaluation of this new technique. These performance and economic results indicate good promise for near-term commercialization of an integrated gasification combined cycle power plant using current gas turbine firing temperatures. Also, these data show that advancements in turbine firing temperature are expected to provide sufficiently favorable economics for the concept to penetrate the market now held by conventional steam power plants.
Software for Flight Critical Digital Engine Controls
Authors: Eccles E. S.
Published: April 2015

Certain types of failure in aircraft gas turbines can have effects which prejudice the safety of flight of the aircraft in which they are installed. The failures can be directly caused by software deficiencies in a digital engine control. The paper reviews the basic issues in achieving software safety of a level required for certification and discusses the effects of these issues. The discussion addresses particularly choice of language; specification, design validation and test procedures throughout the life of a given set of control software.
The Hybrid Diffuser
Authors: Adkins R. C. , Matharu D. S. , Yost J. O.
Published: April 2015

A vortex controlled diffuser has recently been reported (1), which attained high levels of pressure recovery within a short length. This diffuser has, however, achieved only a limited application because of its bleed-off requirements. The present work indicates a means by which this disadvantage can be overcome by using a hybrid arrangement of conventional and vortex controlled diffusers. The outcome was an efficient diffuser, half the length of the equivalent conical diffuser, and which would operate satisfactorily without either bleed-off or vanes projecting into the flow.
Design and Operation of Low-NOx Combustors With Medium Heating Value, Coal-Derived Gas
Authors: Grant J. R. , Holladay T. E. , Boenig F. H. , Duncan R. L.
Published: April 2015

Industrial turbines fired on medium heating value (MHV) gas (nominally 300 Btu/scf) synthesized from coal offer an attractive alternative means of producing electrical power in the future. Peak flame temperatures resulting from combustion of this MHV gas in conventional diffusion flame combustors may be comparable to those of natural gas, yielding undesirably high concentrations of NOx. This paper describes an EPRI-sponsored program conducted to demonstrate a MHV gas turbine combustor capable of meeting EPA NOx requirements without water injection. Program objectives were to design, fabricate, and test three MHV combustor configurations and to demonstrate NOx emissions concentrations of 15 ppmv (dry basis) or less at a burner inlet pressure of 1.27 atm: Design of the combustors was based on a lean-premix fuel metering concept. Tests were conducted in a single-can combustor rig at simulated engine conditions ranging from 40 to 125 percent of engine baseload (74 MW).
Design Study for a Fuel Efficient Turbofan Engine
Authors: Kingcombe R. C. , Dunning S. W.
Published: April 2015

An engine design study is presented in which the target is a 15 percent reduction in installed specific fuel consumption over the large engines currently in service while still meeting anticipated noise and emissions regulations. The fuel saving is achieved with a low specific thrust (bypass ratio 10) and a high overall cycle pressure ratio (42 at cruise). A three-shaft design is proposed, employing highly loaded components in order to reduce the number of turbomachinery stages and hence keep down cost and weight. It is argued that this approach is the one most compatible with projected technological advances. The engine configuration is given and the key features explained, highlighting areas where further research would be of particular advantage. Finally, the predicted engine performance is given, together with an estimate of the savings in direct operating cost.
The Energy Efficient Engine (E3): Advancing the State of the Art
Authors: Gardner W. B. , Gray D. E.
Published: April 2015

The NASA sponsored E3 Program, being conducted by Pratt & Witney Aircraft, is described, including program objectives and goals. The evolution of the Flight Propulsion System design and the related work of the aircraft manufacturers is discussed. The status of the component technology substantiation program is summarized.
Balancing of a Power-Transmission Shaft With the Application of Axial Torque
Authors: Zorzi E. S. , Flemming D.
Published: April 2015

Evaluation of power transmission shafting for high-speed balancing has shown that when axial torque is applied, the imbalance response is altered. An increase in synchronous excitation always occurs if the axial torque level is altered from the value used during balancing; this was the case even when the shaft was balanced with torque applied. The twisting of the long slender shaft produces a change in the imbalance distribution sufficient to disrupt the balanced state. This paper presents a review of the analytic development of a weighted least squares approach to influence coefficient balancing and a review of experimental results. The analytic approach takes advantage of the fact that the past testing has shown that the influence coefficients are not significantly affected by the application of axial torque. The 3.60-m (12-ft) long aluminum shaft, 7.62 cm (3 in.) in diameter was run through the first flexural critical speed at torque levels ranging from zero-torque to 903.8 N-M (8000 lb-in.) in 112.9 N-M (1000 lb-in.) increments. Good comparison was achieved between predicted and experimental results.
Effect of Sodium, Potassium, Magnesium, Calcium, and Chlorine on the High Temperature Corrosion of IN-100, U-700, IN-792, and MAR M-509
Authors: Lowell C. E. , Sidik S. M. , Deadmore D. L.
Published: April 2015

The effects of potential impurities, such as Na, K, Mg, Ca, and Cl, in coal-derived liquid fuels on accelerated corrosion of IN-100, U-700, IN-792, and Mar M-509 were investigated using a Mach 0.3 burner rig for times to 200 hours in one hour cycles. These impurities were injected in combination as aqueous solutions into the combustor. Other variables were time, temperature, and fuel-to-air ratio. The experimental matrix was a central composite fractional factorial design divided into blocks to allow modification of the design as data was gathered. The extent of corrosion was determined by metal consumption, τ.
Turbopropulsion Combustion Research Needs
Authors: Mellor A. M. , Leonard P. A. , Henderson R. E.
Published: April 2015

The research needs in turbopropulsion combustion are itemized, based on a broad survey of the U.S. aircraft engine manufacturers conducted by a joint Air Force – Navy – Army technology assessment team during the Fall of 1978. Much of this research is basic in nature, involving fluid and solid mechanics, heat transfer, and combustion. This brief review of the findings is directed to members of the fundamental research community as a way of further aligning their interests with industry needs.
Light Weight Gas Turbine Drivers: Newest Trend in LNG Plant Design
Authors: Hauck R. L. , Grin W. , DiNapoli R. N.
Published: April 2015

During recent years, the use of gas turbine driven compressors for natural gas liquefaction has been getting increased attention. This paper will describe the application of lightweight Modular Industrial Turbines to conventional liquefaction processes.
Erosion Characteristics of Transpiration Cooled Materials
Authors: Raj R. , Moskowitz S.
Published: April 2015

The paper presents results of an experimental study of the erosion of transpiration air cooled blade materials. Five samples of porous wire meshes for gas turbine blade airfoil applications were subjected to erosion test with alumina. Three of the configurations of meshes were of woven structure, the other two of a wound structure. The erosion was evaluated at various angles of impact from 20 to 90 deg. The critical angle of impact was established for all five samples. The results are compared to that for a solid material sample. The paper also presents an overall plan for erosion testing of transpiration cooled materials and provides information on erosion related work.
Gas Turbine Ferries: An Update
Authors: Lauriat T. B.
Published: April 2015

The use of gas turbines in propulsion systems of ferryboats represents the highest rate of operating time buildup of any marine propulsion application. This paper will review the history of three such ferry operations which have accrued significant time at sea. Particular attention will be given the problems encountered, their solution and status at the time of this paper’s writing. Earlier papers have discussed the details of installation and sea trials of the San Francisco Ferries, the Sedam ferries and the Westamarin ferries. Sufficient time has passed so that an update seems appropriate covering problems that high usage marine installations have brought to light. The three vessels, although all ferries, ply trade routes which impose significantly different engine operation scenarios. Further, the craft themselves, to a certain extent, require control features which impose different engine operating characteristics.
Low NOx Heavy Fuel Combustor Program
Authors: Lister E. , Niedzwiecki R. W. , Nichols Lester
Published: April 2015

The “Low NOx Heavy Fuel Combustor Program” is a part of the DOE/LeRC “Advanced Conversion Technology Project” (ACT). The program is a multiple contract effort with funding provided by the Department of Energy, and technical program management provided by NASA LeRC. Main program objectives are to generate and demonstrate the technology required to develop durable gas turbine combustors for utility and industrial applications, which are capable of sustained, environmentally acceptable operation with minimally processed petroleum residual fuels. The program will focus on “dry” reductions of oxides of nitrogen (NOx), improved combustor durability and satisfactory combustion of minimally processed petroleum residual fuels. Other technology advancements sought include: fuel flexibility for operation with petroleum distillates, blends of petroleum distillates and residual fuels, and synfuels (fuel oils derived from coal or shale); acceptable exhaust emissions of carbon monoxide, unburned hydrocarbons, sulfur oxides and smoke; and retrofit capability to existing engines.
Operation and Test of a New 37 MW Gas Turbine Package Power Plant
Authors: Jermanok J. , Keith R. E. , Backhaus E. F.
Published: April 2015

A new 37-MW, single-shaft gas turbine power plant has been designed for electric power generation, for use in either simple-cycle or combined-cycle applications. This paper describes the design features, instrumentation, installation, test, and initial operation.
Failure mode and effects analysis and fault tree analysis of surface image guided cranial radiosurgery
Authors: Manger Ryan P. , Paxton Adam B. , Pawlicki Todd , Kim Gwe‐Ya
Published: April 2015

Purpose:

Surface image guided, Linac‐based radiosurgery (SIG‐RS) is a modern approach for delivering radiosurgery that utilizes optical stereoscopic imaging to monitor the surface of the patient during treatment in lieu of using a head frame for patient immobilization. Considering the novelty of the SIG‐RS approach and the severity of errors associated with delivery of large doses per fraction, a risk assessment should be conducted to identify potential hazards, determine their causes, and formulate mitigation strategies. The purpose of this work is to investigate SIG‐RS using the combined application of failure modes and effects analysis (FMEA) and fault tree analysis (FTA), report on the effort required to complete the analysis, and evaluate the use of FTA in conjunction with FMEA.

Methods:

A multidisciplinary team was assembled to conduct the FMEA on the SIG‐RS process. A process map detailing the steps of the SIG‐RS was created to guide the FMEA. Failure modes were determined for each step in the SIG‐RS process, and risk priority numbers (RPNs) were estimated for each failure mode to facilitate risk stratification. The failure modes were ranked by RPN, and FTA was used to determine the root factors contributing to the riskiest failure modes. Using the FTA, mitigation strategies were formulated to address the root factors and reduce the risk of the process. The RPNs were re‐estimated based on the mitigation strategies to determine the margin of risk reduction.

Results:

The FMEA and FTAs for the top two failure modes required an effort of 36 person‐hours (30 person‐hours for the FMEA and 6 person‐hours for two FTAs). The SIG‐RS process consisted of 13 major subprocesses and 91 steps, which amounted to 167 failure modes. Of the 91 steps, 16 were directly related to surface imaging. Twenty‐five failure modes resulted in a RPN of 100 or greater. Only one of these top 25 failure modes was specific to surface imaging. The riskiest surface imaging failure mode had an overall RPN‐rank of eighth. Mitigation strategies for the top failure mode decreased the RPN from 288 to 72.

Conclusions:

Based on the FMEA performed in this work, the use of surface imaging for monitoring intrafraction position in Linac‐based stereotactic radiosurgery (SRS) did not greatly increase the risk of the Linac‐based SRS process. In some cases, SIG helped to reduce the risk of Linac‐based RS. The FMEA was augmented by the use of FTA since it divided the failure modes into their fundamental components, which simplified the task of developing mitigation strategies.
Impact of future climate change on a genetic plantation of hybrid pine
Authors: Chhin Sophan
Published: April 2015

European black pine (Pinus nigra Arnold) and Japanese red pine (Pinus densiflora Siebold & Zucc.) are nonnative conifers that have been introduced into the United States and have the ability to hybridize with each other and can potentially become an invasive threat. Interspecific hybridization is an important component of applied genetic tree improvement programs. This study retrospectively examined the influence of climate on interannual growth patterns of 12 full-sib families of hybrid pine that were derived from the hybridization of European black pine and Japanese red pine. The hybrids (Pinus nigra × Pinus densiflora) were initially planted in 1982 in southern mid-Michigan at Michigan State University (MSU) Sandhill Research Area. Tree-ring analysis methods (dendrochronology) were used to quantify the influence of climate (i.e., mean temperature and moisture index) on interannual basal area growth rates of the hybrid pine over an 18 year period (1991–2008). The productivity of the 12 full-sib families of hybrid pine were also projected under future climate change in the 21st century based on the IPCC A1B emission scenario. Climatic sensitivities that were identified in the hybrid pine families included high temperature stress in the summer and fall, moisture stress in the summer, winter harshness, and the timing of the start of the growing season. According to projections, by the end of the 21st century, 8 out of the 12 pine families will show significant decreases in growth outside of the historical norm under the temperature-based dendrochronology models, while 4 families will show significant declines under the moisture index models. The results indicate that the hybrid pine families appear to be generally resilient to future changes in moisture, but will likely be extremely vulnerable to future climatic warming, and thus do not appear to be a future invasive threat. This study represents the first dendrochronological examination of hybrid pine in North America.
Wegner estimate and localization for alloy-type models with sign-changing exponentially decaying single-site potentials
Authors: Leonhardt Karsten , Peyerimhoff Norbert , Tautenhahn Martin , Veselić Ivan
Published: April 2015

We study Schrödinger operators on L2(ℝd) and ℓ2(ℤd) with a random potential of alloy-type. The single-site potential is assumed to be exponentially decaying but not necessarily of fixed sign. In the continuum setting, we require a generalized step-function shape. Wegner estimates are bounds on the average number of eigenvalues in an energy interval of finite box restrictions of these types of operators. In the described situation, a Wegner estimate, which is polynomial in the volume of the box and linear in the size of the energy interval, holds. We apply the established Wegner estimate as an ingredient for a localization proof via multiscale analysis.
Reconstruction of images from Gabor graphs with applications in facial image processing
Authors: Günther Manuel , Böhringer Stefan , Wieczorek Dagmar , Würtz Rolf P.
Published: April 2015

Graphs labeled with complex-valued Gabor jets are one of the important data formats for face recognition and the classification of facial images into medically relevant classes like genetic syndromes. We here present an interpolation rule and an iterative algorithm for the reconstruction of images from these graphs. This is especially important if graphs have been manipulated for information processing. One such manipulation is averaging the graphs of a single syndrome, another one building a composite face from the features of various individuals. In reconstructions of averaged graphs of genetic syndromes, the patients' identities are suppressed, while the properties of the syndromes are emphasized. These reconstructions from average graphs have a much better quality than averaged images.
Transversality versus ellipticity on pseudo-Riemannian manifolds
Authors: Abdelmalek Mohammed , Benalili Mohammed
Published: April 2015

In this paper, we establish sufficient conditions for transversality of two hypersurfaces of a given pseudo-Riemannian manifold. These conditions are the ellipticity of some operators obtained by means of Newton transformations.
Logarithmic means and double series of Bessel functions
Authors: Berndt Bruce C. , Kim Sun
Published: April 2015

In his lost notebook, Ramanujan recorded two identities involving double series of Bessel functions that are closely connected with the classical, unsolved circle and divisor problems. In a series of papers with Zaharescu, the authors proved these identities under various interpretations, as well as Riesz mean analogues. In this paper, logarithmic mean analogues, also involving double series of Bessel functions, are established. Weighted divisor sums involving characters play a central role.
A novel yellowish white Dy3+ activated α-Al2O3 phosphor: Photoluminescence and optical studies
Authors: Kumar Sandeep , Prakash Ram , Kumar Vinay
Published: April 2015

Trivalent Dy doped α- Al 2 O 3 phosphor was synthesized by low temperature solution combustion method using urea as fuel. The phosphor was well characterized by X-ray diffraction (XRD), photoluminescence (PL) spectroscopy and diffused reflectance spectroscopy (DRS). XRD study confirmed the hexagonal structure of Dy 3+ doped α- Al 2 O 3 as prepared phosphor. Under various ultraviolet (UV) excitations (353 nm, 367 nm and 325 nm), α- Al 2 O 3: Dy 3+ phosphor exhibits the characteristic emission bands centered at 490 nm, 589 nm and 670 nm, resulting from the 4 F 9/2–6 H J /2 ( J = 15, 13, 11) transitions of Dy 3+, respectively. The observed CIE coordinates (x, y) as (0.373, 0.379) corresponds to the shade of yellowish white in color gamut. The bandgap was calculated using diffused reflectance (DR) spectrum and it was estimated around 5.9 eV.
Verification of a Cryptographic Primitive
Authors: Appel Andrew W.
Published: April 2015

This article presents a full formal machine-checked verification of a C program: the OpenSSL implementation of SHA-256. This is an interactive proof of functional correctness in the Coq proof assistant, using the Verifiable C program logic. Verifiable C is a separation logic for the C language, proved sound with respect to the operational semantics for C, connected to the CompCert verified optimizing C compiler.
A Novel Artificial Bee Colony Algorithm for Function Optimization
Authors: Zhang Song , Liu Sanyang
Published: April 2015

It is known that both exploration and exploitation are important in the search equations of ABC algorithms. How to well balance the two abilities in the search process is still a challenging problem in ABC algorithms. In this paper, we propose a novel artificial bee algorithm named as “NABC,” by incorporating the information of the global best solution into the solution search equation of the onlookers stage to improve the exploitation. At the same time, we improve the search equation of the employed bees to keep the exploration. The experimental results of NABC tested on a set of 11 numerical benchmark functions show good performance and fast convergence in solving function optimization problems, compared with variant ABC, DE, and PSO algorithms. The application of NABC on solving five standard knapsack problems shows its effectiveness and practicability.
The Physical and Chemical Properties of Fine Carbon Particles-Pinewood Resin Blends and Their Possible Utilization
Authors: Melapi Aviwe , Mamphweli Sampson N. , Katwire David M. , Meyer Edson L.
Published: April 2015

The application of biomass gasification technology is very important in the sense that it helps to relieve the dwindling supply of natural gas from fossil fuels, and the desired product of its gasification process is syngas. This syngas is a mixture of CO and H2; however, by-products such as char, tar, soot, ash, and condensates are also produced. This study, therefore, investigated selected by-products recovered from the gasification process of pinewood chips with specific reference to their potential application in other areas when used as blends. Three samples of the gasification by-products were obtained from a downdraft biomass gasifier system and were characterized in terms of chemical and physical properties. FTIR analysis confirmed similar spectra in all char-resin blends. For fine carbon particles- (soot-) resin blends, almost the same functional groups as observed in char-resin blends appeared. In bomb calorimeter measurements, 70% resin/30% char blends gave highest calorific value, followed by 50% resin/50% soot blends with values of 35.23 MJ/kg and 34.75 MJ/kg consecutively. Provided these by-products meet certain criteria, they could be used in other areas such as varnishes, water purification, and wind turbine blades.
Selection of Reference Genes for Quantitative Gene Expression in Porcine Mesenchymal Stem Cells Derived from Various Sources along with Differentiation into Multilineages
Authors: Lee Won-Jae , Jeon Ryoung-Hoon , Jang Si-Jung , Park Ji-Sung , Lee Seung-Chan , Baregundi Subbarao Raghavendra , Lee Sung-Lim , Park Bong-Wook , King William Allan , Rho Gyu-Jin
Published: April 2015

The identification of stable reference genes is a prerequisite for ensuring accurate validation of gene expression, yet too little is known about stable reference genes of porcine MSCs. The present study was, therefore, conducted to assess the stability of reference genes in porcine MSCs derived from bone marrow (BMSCs), adipose (AMSCs), and skin (SMSCs) with their in vitro differentiated cells into mesenchymal lineages such as adipocytes, osteocytes, and chondrocytes. Twelve commonly used reference genes were investigated for their threshold cycle (Ct) values by qRT-PCR. The Ct values of candidate reference genes were analyzed by geNorm software to clarify stable expression regardless of experimental conditions. Thus, Pearson’s correlation was applied to determine correlation between the three most stable reference genes (NF3) and optimal number of reference genes (NFopt). In assessment of stability of reference gene across experimental conditions by geNorm analysis, undifferentiated MSCs and each differentiated status into mesenchymal lineages showed slightly different results but similar patterns about more or less stable rankings. Furthermore, Pearson’s correlation revealed high correlation (r>0.9) between NF3and NFopt. Overall, the present study showed thatHMBS,YWHAZ,SDHA, andTBPare suitable reference genes for qRT-PCR in porcine MSCs.
Impact of Inflammatory Cytokine Gene Polymorphisms on Developing Acute Graft-versus-Host Disease in Children Undergoing Allogeneic Hematopoietic Stem Cell Transplantation
Authors: Masetti Riccardo , Zama Daniele , Urbini Milena , Astolfi Annalisa , Libri Virginia , Vendemini Francesca , Morello William , Rondelli Roberto , Prete Arcangelo , Pession Andrea
Published: April 2015

Single nucleotide polymorphisms (SNPs) in gene encoding pro- and anti-inflammatory factors have been associated with the occurrence of aGvHD. We retrospectively tested a wide panel of 38 polymorphisms in 19 immunoregulatory genes, aiming to first establish, in a pediatric HSCT setting, which SNPs were significantly associated with the development of aGvHD. A significant association was found between aGvHD grades II–IV and SNPs of donor IL10-1082GG, and Fas-670CC + CT and recipient IL18-607 TT + TG genotype. aGvHD grades III-IV resulted associated with donor IL10-1082GG, Fas-670CC + CT, and TLR4-3612TT as well as the use of peripheral CD34+ cells as stem cell source. The multivariate analysis confirmed the association between donor IL10-1082GG and Fas-670CC + CT and aGvHD grades II–IV and between donor IL10-1082GG and TLR4-3612TT and aGvHD grades III-IV. In conclusion we found an association between IL10, FAS, and TLR4 in the donor and IL18 in the recipient and an increased risk of developing aGvHD in transplanted children. Knowledge of the SNPs of cytokine genes associated with aGvHD represents a useful tool for an integrated pretransplantation risk assessment and could guide the physicians to an optimal and more accurate HSCT planning.
Vitamin D and Atopic Dermatitis in Childhood
Authors: Vestita Michelangelo , Filoni Angela , Congedo Maurizio , Foti Caterina , Bonamonte Domenico
Published: April 2015

Vitamin D features immunomodulatory effects on both the innate and adaptive immune systems, which may explain the growing evidence connecting vitamin D to allergic diseases. A wealth of studies describing a beneficial effect of vitamin D on atopic dermatitis (AD) prevalence and severity are known. However, observations linking high vitamin D levels to an increased risk of developing AD have also been published, effectively creating a controversy. In this paper, we review the existing literature on the association between AD and vitamin D levels, focusing on childhood. As of today, the role of vitamin D in AD is far from clear; additional studies are particularly needed in order to confirm the promising therapeutic role of vitamin D supplementation in childhood AD.
A Convex-Risk-Measure Based Model and Genetic Algorithm for Portfolio Selection
Authors: Wang Weijia , Hu Jie , Dong Ning
Published: April 2015

A convex risk measure called weighted expected shortfall (briefly denoted as WES (Chen and Yang, 2011)) is adopted as the risk measure. This measure can reflect the reasonable risk in the stock markets. Then a portfolio optimization model based on this risk measure is set up. Furthermore, a genetic algorithm is proposed for this portfolio optimization model. At last, simulations are made on randomly chosen ten stocks for 60 days (during January 2, 2014 to April 2, 2014) from Wind database (CFD) in Shenzhen Stock Exchange, and the results indicate that the proposed model is reasonable and the proposed algorithm is effective.
Multicriteria Decision Model to Support the Assignment of Storage Location of Products in a Warehouse
Authors: da Silva Denilson Dimas , de Vasconcelos Natália Veloso Caldas , Cavalcante Cristiano Alexandre Virginio
Published: April 2015

The storage of products has a strategic role in the supply chain: an efficient organization of products in appropriate locations enables these products to be moved faster inside the warehouse and logistics channel, which increases the speed of delivery and the competitiveness of enterprises. The aim of this paper is to propose a multicriteria decision support model for ranking products and assigning them to warehouse storage locations. During the structuring of the model, the nature of the problem was defined as multicriteria; therefore, the SMARTER and lexicographic methods were applied. The results showed an ordering of products that allowed their strategic location in a hypothetical nonautomated warehouse.