bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preventive dental health care experiences of preschool‐age children with special health care needs
Authors: Huebner Colleen E. , Chi Donald L. , Masterson Erin , Milgrom Peter 
Published: August 2014

ABSTRACTPurposeThis study examined the preventive dental health care experiences of young children with special needs and determined the feasibility of conducting clinical dental examinations at a community‐based early intervention services center.MethodsStudy methods included 90 parent interviews and dental examinations of their preschool‐age children.ResultsThirteen percent of the children received optimal preventive care, defined as twice daily tooth brushing with fluoridated toothpaste and two preventive dental visits in the prior 12 months; 37% experienced care that fell short in both areas. Optimal care was more common among children of parents who reported tooth brushing was not a struggle and those with a personal dentist. Parents’ opinion of the study experience was generally positive.ConclusionsFew children with special needs receive effective preventive care early, when primary prevention could be achieved. Barriers to optimal care could be readily addressed by the dental community in coordination with early intervention providers.
The health implications of low hemoglobin deferral in infrequent blood donors
Authors: Annen Kyle , Delaney Meghan , Leitch Dave , Mast Alan E. 
Published: August 2014

BackgroundThe causes of anemia in infrequent blood donors deferred for low hemoglobin (Hb) are not well known. We sought to assess this via surveys of infrequent, nonmenstruating deferred blood donors at two institutions, BloodCenter of Wisconsin and Puget Sound Blood Center.Study Design and MethodsMen at least 18 years of age and women at least 50 years of age who were deferred for low Hb (≤12.5 g/dL), had not more than one donation in the year prior to deferral, and did not successfully donate in the 3 months after their deferral were surveyed.ResultsThe total response rate was 380 donors or 34% of those contacted. Of the respondents, 141 had sought medical advice about their low Hb. Of these, 90 were confirmed to have anemia and 13 reported serious disease requiring medical intervention, including mantle cell lymphoma, multiple myeloma, and gastrointestinal bleeding.ConclusionsA small but concerning number of infrequent blood donors deferred for low Hb have an underlying illness that is severe and would benefit from medical attention. Donors deferred for low Hb who have a high risk for serious underlying illness should be provided targeted educational information advising them to seek additional medical care.
The Use of Variable Fidelity Models in the Optimization Problems for Aircraft Engines Parameters and Control Laws
Authors: Egorov I. N. , Kretinin G. V. , Leshchenko I. A. , Babiy Y. I. 
Published: August 2014

The typical situation when solving a problem of an aircraft engine optimization is that a researcher has several tools for effectiveness indices analysis, distinguished according to the levels of complexity and accuracy. The high-fidelity tools can be the detailed nonlinear mathematical models or even the experimental samples of the engine or its components. However the implementation of optimization researches using such a tools is associated with the significant time expenditures. The low-fidelity models also allow us to carry out optimization search, but the validity of the obtained results can be rather low. Therefore the methods based on a combination of various levels of the analysis tools are going to be used in the field of optimization of the aircraft engines parameters and control laws.
The given paper introduces the multicriteria optimization procedure for aircraft power plants and their components. The procedure is based upon the adaptive use of different levels analysis tools. The proposed approach is intended to minimize the complicated analysis tools application. It uses the method of indirect optimization on the base of self-organization, which permits to find numerically the Pareto-optimal set of solutions, uniformly distributed in the criteria space.
The effectiveness of the proposed optimization procedure is demonstrated by two examples. The first one is a problem to find the optimal control laws for the power plant of short take-off and vertical landing aircraft for its take-off (50 variables, 2 criteria). The second one is the problem of multistage axial compressor optimization aimed at its efficiency maximization (42 variables, 2 criteria).
A New Compressor Map Scaling Procedure for Preliminary Conceptional Design of Gas Turbines
Authors: Kurzke Joachim , Riegler Claus 
Published: August 2014

In the preliminary conceptional design phase of any new gas turbine project the design and off-design performance of many alternative configurations and cycles must be studied. The simulation results for the off-design cases depend very much on the component maps employed in the model. Especially important are the compressor maps, and when the pre-design study covers a wide range in pressure ratio, then the use of a consistent set of maps is essential for high quality simulation results.
A statistical analysis of many compressor maps — taken from open literature and from the MTU in house data bank — was performed. In each map a reference point was defined which was employed to normalize it. Then, the topology of the normalized map was captured with three characteristic numbers that describe 1) the region where efficiency is highest, 2) the mass flow – speed relationship and 3) the shape of the speed lines.
The characteristic numbers show in the statistic evaluation clear trends with reference pressure ratio. From these trends a new map scaling procedure was derived which describes the systematic change of the compressor map topology with design pressure ratio much better than the conventional map scaling method, which applies constant factors on pressure ratio or on specific work.
Steady Performance Measurements of a Turbofan Engine With Inlet Distortions Containing Co- and Counter-Rotating Swirl From an Intake Diffuser for Hypersonic Flight
Authors: Schmid Norbert R. , Leinhos Dirk C. , Fottner Leonhard 
Published: August 2014

The influence of distorted inlet flow on the steady and unsteady performance of a turbofan engine which is a component of an airbreathing combined propulsion system for a hypersonic transport aircraft is reported in this paper. The performance and stability of this propulsion system depends on the behavior of the turbofan engine. The complex shape of the intake duct causes inhomogeneous flow at the engine inlet plane, where total pressure and swirl distortions are present. The S-bend intakes are installed axisymmetrically left and right into the hypersonic aircraft hence generating axisymmetrical mirror inverted flow patterns. Since all turbo engines of the propulsion system have the same direction of rotation, one distortion corresponds to a co-rotating swirl at the low pressure compressor (LPC) inlet while the mirror inverted image counterpart represents a counter-rotating swirl. Therefore the influence of the distortions on the performance and stability of the ‘CO’ and ‘COUNTER’ rotating turbo engine are differing, respectively. Both distortions were generated separately by an appropriate simulator at the inlet plane of a LARZAC 04 engine. The results of low frequency measurements at different engine planes yield the relative variations of thrust and specific fuel consumption and hence the steady engine performance.
High frequency measurements were used to investigate the different influence of CO and COUNTER inlet distortions on the development of LPC instabilities.
The Potential Impact of Utilizing Advanced Engine Technology for a Combat Capable Unmanned Air Vehicle (UAV)
Authors: Bruening Greg B. , Snyder James R. , Fredette Raymond E. 
Published: August 2014

This paper evaluates the potential impact of utilizing advanced engine technology for a limited life, combat capable, unmanned air vehicle (UAV) application. A study was conducted to define payoffs in terms of mission capability and system level life cycle costs (LCC) associated with implementing three different engine development approaches into a combat capable UAV design. The three different approaches considered were: a new, advanced technology engine; an existing (off-the-shelf) engine; and a derivative of an existing engine with limited technology insertion. A detailed vehicle configuration design was developed to conduct this assessment, including a low observable (LO), highly integrated engine/airframe layout for survivability and mission adaptable considerations. The vehicle is designed with multi-role mission capability such as suppression of enemy air defense (SEAD), close air support (CAS), and battlefield air interdiction (BAI). A system level performance comparison is assessed with the three different engine approaches, specifically for the SEAD-type mission. For the cost analysis, the multi-role mission capability is reflected in the overall assumptions such as in the number of aircraft needed to meet the mission requirements.
A system level assessment such as in this study is essential in determining whether the additional costs associated with the development of a new, advanced engine is worth the investment. The results of this study suggest that advanced engine technology insertion can provide significant benefits in terms of mission range capability, vehicle weight/size, and overall life cycle costs versus an existing engine.
Concepts for the Production of Biomass Derived Fuel Gases for Gas Turbine Applications
Authors: Schmitz W. , Hein D. 
Published: August 2014

Amongst the available alternatives of regenerative energy sources, biomass may play an important role in the future. Biomass represents stored solar energy, accessible whenever there is demand. But so far, its large potential has only been used to a small extent. This is partly due to the fact that solid biomass is a common fuel for the production of heat, but is hardly used in combined heat and power (CHP) plants.
For the conversion of solid fuels, combustion in combination with a Rankine cycle is the only well established technology available today, thus acceptable net efficiencies (> 25% LHV) are only possible in complex, rather large scale plants.
However, since the occurrence of biomass differs depending on region and season, and because of its low energy density and thus reduced transportability, biomass is particularly suited for decentralized applications, i.e. for the generation of heat and power (1) in the small power range.
This paper discusses strategies for the integration of biomass gasification / pyrolysis and gas cleaning processes into different gas turbine schemes. Rather than reviewing all possible aspects of and concepts for the usage of biomass in gas turbine applications, this paper evaluates some key aspects (pressurization, tar removal, gas cleaning, choice of gas turbine cycle) of directly fired gas turbine concepts with regard to small scale applications.
The paper shows that tar is a key problem. Especially for small scale applications solutions based on the combustion of tars, like pressurized biomass conversion in combination with hot gas cleaning, prove to be simple and efficient.
This paper also compares the characteristics of integrated gasification cycles, e.g. by demonstrating difficulties connected with the integration of steam blown allothermal gasification (reforming). Furthermore, it is shown that recuperated gas turbines are well suited for highly efficient, yet simple small scale applications.
Test results indicate that “mild” pyrolysis is an alternative technology for the production of comparatively clean medium heating value gases. Integrating the use of pyrolysis gas and charcoal into a simple gas turbine plant, however, can not easily be achieved.
Designing Diagnostic Expert Systems for Long-Term Supportability
Authors: Forsyth Graham , Delaney John 
Published: August 2014

In the late 1980s, the Royal Australian Air Force (RAAF) investigated the use of computer-based technology to improve diagnostic troubleshooting methods. One such technology was demonstrated in an Interactive Fault Diagnosis and Isolation System (IFDIS) that was produced by Competitive Advantage Technology Pty Ltd under direction from the Defence Science and Technology Organisation (DSTO).
This paper describes a new design which aims to improve the long-term supportability of such diagnostic systems by making the maximum use of commercial software, producing clear separation of technical information from any software elements, writing all non-standard software using defined standards and generally making the most possible use of the advances in computing over the last ten years.
The system is now in field trial with the aim of developing procedures and specifications for production.
An Investigation of Artificial Neural Network (ANN) in Quantitative Fault Diagnosis for Turbofan Engine
Authors: Bin Sun , Jin Zhang , Shaoji Zhang 
Published: August 2014

This paper is aimed at investigating two kinds of Artificial Neural Network (ANN) applied to quantitative fault diagnosis of turbofan engine gas path components. Among them, one is Back Propagation neural Network (BPN) and the other is Adaptive Probabilistic Neural Network (APNN).
Using BPN in order to achieve quantitative fault diagnosis, number of training samples will increase greatly which may lead to the difficulty of iteration convergence. A new learning rule named hybrid rule is introduced to avoid the algorithm falling into static areas and expedite convergence.
Recently, a new method to improve the adaptability of multi-layer feed-forward neural network has been developed by the application of Radial Basis Function (RBF). In this paper, the APNN is put forward based on the theory of radial basis function, Bayesian estimation and normal distribution hypothesis of information. It is proposed that the adaptability of APNN can be obtained by applying maximum-likelihood estimation of the output of test case based on a posteriori probability of its input.
The investigation shows that BPN and APNN have their own advantages and disadvantages. BPN has faster diagnostic speed and fits the requirement of quantitative diagnosis for single fault. APNN is more adaptive and fit better to quantitative diagnosis for multiple faults.
Neural Networks Based Diagnostics for Mistuned Bladed Disk
Authors: Peng Pei-Yuan , Yang M. T. 
Published: August 2014

Neural networks based diagnostics is studied in this paper for the fault/alert assessment of the mistuned bladed disk. By randomly varying the blades frequencies (± 2% of the nominal frequencies), we experimentally collected 1000 sets of data. Each set of data is composed of blade frequencies, maximal vibrating magnitude for each blade with the corresponding frequency. The goal is to investigate the mapping relationship from the blade property (blade frequency) to maximal vibrating displacement and the corresponding frequency.
Assuming the system is forced by a traveling excitation, the vibration/frequency signature is derived. The challenging part stems from mistuned bladed disk system, where every blade performs differently for the same input excitement. The neural networks based diagnostics system demonstrate its capability to identify the mapping relation for this complex system.
The simulation is based on a finite element model of bladed disk system and the results exhibit the effectiveness of the proposed algorithm.
Performance of Gas Turbine Power Plants Controlled by One Step Ahead Adaptive Technique
Authors: Dambrosio L. , Camporeale S. M. , Fortunato B. 
Published: August 2014

The One Step Ahead Controllers represent a branch of the Minimum Prediction Error Adaptive Controllers. They combine the parameter estimation of the controlled system model with a particular control scheme; therefore, they are especially suitable for non-linear and time-varying systems. Since the estimated parameters are updated at each time step (by using the sampled data), these methods can be adopted for real-time applications. Consequently, the One Step Ahead Controllers do not require the knowledge of the dynamic characteristics of the controlled system (e.g. state space systems or transfer functions).
The One Step Ahead Adaptive (OSAA) algorithm combines the Least Square Algorithm (LSA) parameter estimator with a Deterministic Auto-Regressive Moving Average (DARMA) control scheme. The DARMA model can be characterized with a different number of time steps in the past (order of the estimated model) in relation to the dynamic feature of the controlled system.
Sometimes, an excessive control effort could arise, caused by sudden variations of the electric load. In order to reduce this control action, the OSAA control technique has been applied also in Weighted fashion. The Weighted One Step Ahead Adaptive (WOSAA) control algorithm considers a penalty associated with the control effort by use an appropriate cost function. In this way, the control variable does not assume too large values, even when the Gas Turbine undergoes sudden changes in the external load. As a consequence, the robustness and the stability features of the WOSAA control system are increased with respect to the OSAA algorithm.
The proposed techniques have been applied to a single shaft heavy-duty gas turbine (WOSAA) and to a double-shaft aero-derivative gas turbine (OSAA). They have been tested in Single-Input Single Output (SISO) mode. In the simulation tests, the plant is assumed to undergo sudden variations of the electric load. Second order schemes of the OSAA estimated model have been derived and applied to the double-shaft aero-derivative gas turbine.
The results show that the OSAA control technique, applied to the double-shaft aero-derivative gas turbine, effectively counteracts the load reduction with limited overshoot in the controlled variables and, introducing an integral correction, with a negligible static error. On the other hand, the WOSAA control algorithm is able to efficiently regulate the single shaft heavy-duty gas turbine, and to counteract the sudden variations of the electric load, with reduced control effort.
Advanced Fuel Metering for Aero Engines
Authors: Schwamm Friedrich 
Published: August 2014

Traditionally the fuel system of most modern day aero engines consist of two basic functional blocks;
- pumping system
- fuel metering system.
The pumping system basically consists of a first stage centrifugal pump followed by a second stage gear pump. The function of the pumping system is to provide sufficient fuel at the required pressure to ensure engine operation (steady state and transient) over the complete operating envelope and under the consideration of worst case fuel inlet properties.
The fuel metering system basically consists of a fuel metering valve, an emergency valve and a shut off valve. The fuel metering valve itself is usually realised as controllable main metering valve, the pressure drop across which is hydro-mechanically controlled via a pressure drop regulator. The pressure drop regulator spills the excess fuel delivery back to the pump inlet in order to maintain the constant pressure drop. Whilst this approach to fuel system design has gained world wide industry acceptance, there still remains potential for further simplification and improved system reliability. This paper examines two alternative concepts for future fuel system designs namely,
- Electrically controlled variable speed fuel pump
- Reduced complexity fuel metering unit.
For both systems this paper examines and discusses, the technologies involved and the relative merits of each system in terms of:
• system performance
• fault detection / accommodation
• failure reaction and
• production costs.
Design and Test of a Semi-Passive Flow Control Device for Inlet Distortion Suppression
Authors: Jaw Link C. , Cousins William T. , Wu Dong N. , Bryg David J. 
Published: August 2014

Advanced turbine engines often operate with reduced stability margin to increase performance. Aircraft engine temperature and pressure inlet distortion has a major effect upon the stability of the compression system. Suppression of inlet distortion can provide greater stability margin for the engine, thereby reducing operability restrictions on the engine by allowing closer operation to the stability limit.
SMI has designed and tested a semi-passive distortion suppression system. The system uses flow injection to modify temperature and pressure inlet distortion. The prototype system was tested on a Honeywell T55 compressor rig.
This paper presents both the design of the system and the test results. The test results show that this semi-passive distortion suppression system was able to reduce the surge margin degradation caused by the presence of pressure or temperature distortion. Special design considerations for this type of system are discussed, based upon the results of the prototype test. It is shown that distortion control can be a viable addition to the design of an aircraft engine.
Experimental Investigation of the Blade-to-Blade Flow in a Compressor Rotor by Digital Particle Image Velocimetry
Authors: Balzani N. , Scarano F. , Riethmuller M. L. , Breugelmans F. A. E. 
Published: August 2014

The purpose of this study is to investigate the blade to blade flow in an axial compressor, providing a detailed description of the entire flow-field on multiple layers through the use of Particle Image Velocimetry (PIV).
Typical problems that relate to flow seeding, light-sheet generation and camera-laser timing control are successfully dealt with bringing additional knowledge in the domain.
An extensive data set is analysed to obtain statistical flow information (mean and fluctuating quantities). Spatial data reconstruction procedures allow the complete planar flow distributions to be determined. The multi-planar mean velocity field constitutes the final result of a 3D reconstruction of the domain geometry and the proper introduction of the available planar measurements.