bluuebunny/crossref_metadata_2025 huggingface dataset:
Control of Porosity and Pore Size of Metal Reinforced Carbon Nanotube Membranes
Authors: Dumee Ludovic , Velleman Leonora , Sears Kallista , Hill Matthew , Schutz Jurg , Finn Niall , Duke Mikel , Gray Stephen
Published: December 2010

Membranes are crucial in modern industry and both new technologies and materials need to be designed to achieve higher selectivity and performance. Exotic materials such as nanoparticles offer promising perspectives, and combining both their very high specific surface area and the possibility to incorporate them into macrostructures have already shown to substantially increase the membrane performance. In this paper we report on the fabrication and engineering of metal-reinforced carbon nanotube (CNT) Bucky-Paper (BP) composites with tuneable porosity and surface pore size. A BP is an entangled mesh non-woven like structure of nanotubes. Pure CNT BPs present both very high porosity (>90%) and specific surface area (>400 m2/g). Furthermore, their pore size is generally between 20–50 nm making them promising candidates for various membrane and separation applications. Both electro-plating and electroless plating techniques were used to plate different series of BPs and offered various degrees of success. Here we will report mainly on electroless plated gold/CNT composites. The benefit of this method resides in the versatility of the plating and the opportunity to tune both average pore size and porosity of the structure with a high degree of reproducibility. The CNT BPs were first oxidized by short UV/O3 treatment, followed by successive immersion in different plating solutions. The morphology and properties of these samples has been investigated and their performance in air permeation and gas adsorption will be reported.
Exploratory Spatial Analysis of in vitro Respiratory Syncytial Virus Co-infections
Authors: Simeonov Ivan , Gong Xiaoyan , Kim Oekyung , Poss Mary , Chiaromonte Francesca , Fricks John
Published: December 2010

The cell response to virus infection and virus perturbation of that response is dynamic and is reflected by changes in cell susceptibility to infection. In this study, we evaluated the response of human epithelial cells to sequential infections with human respiratory syncytial virus strains A2 and B to determine if a primary infection with one strain will impact the ability of cells to be infected with the second as a function of virus strain and time elapsed between the two exposures. Infected cells were visualized with fluorescent markers, and location of all cells in the tissue culture well were identified using imaging software. We employed tools from spatial statistics to investigate the likelihood of a cell being infected given its proximity to a cell infected with either the homologous or heterologous virus. We used point processes, K-functions, and simulation procedures designed to account for specific features of our data when assessing spatial associations. Our results suggest that intrinsic cell properties increase susceptibility of cells to infection, more so for RSV-B than for RSV-A. Further, we provide evidence that the primary infection can decrease susceptibility of cells to the heterologous challenge virus but only at the 16 h time point evaluated in this study. Our research effort highlights the merits of integrating empirical and statistical approaches to gain greater insight on in vitro dynamics of virus-host interactions.
Effects of Quantum Dot Labeling on Endothelial Progenitor Cell Function and Viability
Authors: Molnar Matyas , Friberg Peter , Fu Ying , Brisslert Mikeal , Adams Michael , Chen Yun
Published: December 2010

Endothelial progenitor cells (EPC) play an important role in repairing damaged endothelium. An effective imaging method for in vivo tracking of EPCs is essential for understanding EPC-based cell therapy. Fluorescent quantum dots (QDs) have attractive optical characteristics such as extreme brightness and photostability. QDs are currently being investigated as probes for stem cell labeling; however, there is concern about whether QDs can be used safely. We investigated whether quantum dot (QD) labeling would influence EPC viability and function. Rat bone marrow-derived EPCs were cultured and characterized. The cells were labeled with near-infrared-emitting, carboxyl-coated QDs (8 nM) for 24 h. QD labeling efficiency was higher than 97%. Using WST-1 assay, we showed that the viability of the QD-labeled EPCs was not different from that of the control EPCs. Moreover, QD labeling did not influence the ability of EPCs to form capillary tubes on Matrigel and to migrate. The percentage of QD-positive cells decreased with time, probably due to the rapid division of EPCs. These data suggest that the carboxyl-coated QD705 can be useful for labeling EPCs without interrupting their viability and functions.
EXPERIMENTAL ANALYSIS OF IRON IMPACT ON HEAVY METAL (COPPER) MIGRATION IN THE SOIL
Authors: Vaišis Vaidotas , Šuksta Lidija
Published: December 2010

The paper focusses on analysis of the impact of iron particles on heavy metals migration in the soil within the northern area of Klaipeda city. The city has been chosen due to its function as a transit harbour locating 19 big companies related to the sea business and cargo services. Like every ecosystem, the soil is characterized by accumulating different substances with no exclusion of contaminants. For the analysis of iron impact on heavy metals migration, an experimental stand with six fixed columns was constructed. Copper salt solution was passed through the columns on quartz sand with iron filings (1.5 and 10%) in it and without (the control column). Quartz sand was chosen due to its inert properties. The analysis proves that iron forms a geochemical barrier and it has significant impact on the mode of the heavy metal (Cu) migration in the soil. Santrauka Straipsnyje analizuojama geležies daleliu itaka sunkiuju metalu migravimui šiaurineje Klaipedos uosto dalyje. Klaipeda pasirinkta, nes tai tranzitinis uostas, kuriame vyksta kroviniu krovimas, laivu statyba, rekonstravimas ir visos kitos funkcijos, susijusios su jūrine veikla ir krovininiu laivu paslaugomis. Kaip ir kiekvienoje ekosistemoje dirvožemiams būdingos akumuliacines savybes, juose kaupiasi ivairios medžiagos, kartu – ir teršalai. Geležies itakai sunkiuju metalu migravimui tirti buvo sukonstruotas specialus eksperimentinis stendas su šešiomis kolonomis, pro kurias per tiriama terpe – kvarcini smeli (nes jis yra inertiškas) buvo leidžiamas vario druskos tirpalas. Eksperimente naudotas kvarcinis smelis su geležies drožlemis (1, 5 ir 10 %) ir be ju (kontrolinis). Iš analizes rezultatu akivaizdu, kad geležis turi reikšminga itaka sunkiojo metalo (Cu) migracijos pobūdžiui dirvožemyje bei sukuria geochemini barjera. Резюме Клайпеда – крупный транзитный порт, в котором погрузкой грузов, строительством кораблей и их реконструкцией, а также всеми остальными функциями, касающимися морской деятельности и услуг грузоподъемных кораблей, занимаются 19 больших компаний. Как и каждая экосистема, почва функционирует как накопитель и резервуар материалов, включая и загрязняющие вещества. В статье главное внимание уделено исследованию частиц железа, оказывающих влияние на миграцию тяжелых металлов в северной части города Клайпеды около Клайпедского порта. С этой целью была сконструирована специальная доска с шестью колоннами, через которые в анализируемую среду – кварцевый песок (инертный материал) – пропускался раствор. Для эксперимента был выбран кварцевый песок со стружками железа (1, 5 и 10%) и без него. Результаты анализа показали, что железо оказывает значительное влияние на формы миграции тяжелого металла (меди), а также создает геохимический барьер.
Inhibition of Lytic Reactivation of Kaposi'S Sarcoma-Associated Herpesvirus by Alloferon
Authors: Lee Naeun , Bae Seyeon , Kim Hyemin , Kong Joo Myung , Kim Hang-Rae , Cho Byung Joo , Kim Sung Joon , Seok Seung Hyeok , Hwang Young-il , Kim Sooin , Kang Jae Seung , Lee Wang Jae
Published: December 2010

Background

Alloferon, an immunomodulatory peptide, has antiviral capability against herpesvirus. In this research, we aimed to investigate the effect of alloferon on the regulation of the life cycle of Kaposi's sarcoma-associated herpesvirus (KSHV), and its mechanisms. We also assessed the antiviral activity of alloferon on natural killer (NK) cells as an early antiviral immune responder.

Methods

We first examined the change in cell proliferation and the expression of the viral genes in a KSHV- infected cell line, body-cavity-based B lymphoma (BCBL)-1, under the lytic cycle by 12- O-tetradecanoyl-phorbol-13-acetate (TPA) treatment. To elucidate the antiviral mechanism of alloferon, we tested calcium influx and the activation of the extracellular signal-regulated kinase (ERK) pathway. Furthermore, we evaluated the cytotoxicity of NK cells against BCBL-1 by alloferon.

Results

Alloferon effectively recovered the suppressed proliferation of BCBL-1 by TPA, which was achieved by the down-regulation of lytic-cycle-related viral genes, RTA, K8 and vIRF2. To clarify the signal transduction pathways related to the regulation of the viral genes by alloferon, we confirmed that the calcium influx into BCBL-1 was apparently inhibited by alloferon, which preceded the suppression of the phosphorylation of ERK and the activation of AP-1 by TPA. Moreover, when NK cells were exposed to alloferon, their cytolytic activity was improved, and this was mediated by the enhancement of perforin/granzyme secretion.

Conclusions

The results of this study suggest that alloferon can be used as an effective antiviral agent for the regulation of the KSHV life cycle by the down-regulation of AP-1 activity and for the the enhancement of antiviral immunity by up-regulation of NK cell cytotoxicity.
Macular Hole in a Newborn Associated With Forceps Delivery
Authors: Casillas Malicia , Bazard Marie-Christine , Hubert Isabelle , Berrod Jean-Paul
Published: December 2010

A newborn who had familial high myopia presented with bilateral dense vitreous hemorrhage after forceps delivery. Vitrectomy in the right eye revealed a macular hole surrounded by pigmented cells. After subsequent surgery, the macular hole healed and remained closed during 10 years of follow-up, but profound amblyopia persisted. Macular hole is a possible complication of forceps delivery. Vitrectomy associated with inner limiting membrane peeling and gas tamponade was effective in closing macular hole in a newborn but was unable to prevent amblyopia.
[J Pediatr Ophthalmol Strabismus 2010;47:e1–e3.]
Retinal Detachment Despite Aggressive Management of Aggressive Posterior Retinopathy of Prematurity
Authors: Suk Kevin K. , Berrocal Audina M. , Murray Timothy G. , Rich Ryan , Major James C. , Hess Ditte , Johnson Rose A.
Published: December 2010

Posterior retinopathy of prematurity (ROP) is unusual in its atypical features and its aggressive, rapidly progressive course. It is more difficult to recognize and to treat, with many of these eyes progressing to retinal detachment despite multiple treatments with laser or cryotherapy. The authors present a case of aggressive posterior ROP refractory to multiple laser treatment. This patient was successfully treated with intravitreal bevacizumab, but required repeat treatment 4 months later. The second injection with bevacizumab was followed by progression to retinal detachment requiring surgery. The patient remains stable after surgery.
[J Pediatr Ophthalmol Strabismus 2010;47:e1–e4.]
Transforming the Culture of Caring
Authors: Allen Diane E. , de Nesnera Alexander , Cummings Kathleen , Darling Frank E.
Published: December 2010

Direct care staff struggle with the decision of when to physically intervene with patients. There is a widely held belief that they are expected to place themselves in danger of harm to prevent patients from hurting themselves or others. In this acute mental health care setting, an educational program was developed, using principles of adult and transformational learning, to dispel the idea that getting hurt is part of the job. The Staying Safe program strongly discourages staff from physically intervening alone and promotes staff getting enough help and having a plan. Staff are encouraged to interact with patients in helpful ways and to respond to patient requests in ways that do not increase frustration or evoke anger. There has been a positive response to the training program, evidenced by changes in the way staff think about their jobs and a reduction in the number of assaults and injuries to staff.
Substance P Is a Key Mediator of Stress-Induced Protection from Allergic Sensitization via Modified Antigen Presentation
Authors: Pavlovic Sanja , Liezmann Christiane , Blois Sandra M. , Joachim Ricarda , Kruse Johannes , Romani Nikolaus , Klapp Burghard F. , Peters Eva M. J.
Published: December 2010

Interaction between the nervous and immune systems greatly contributes to inflammatory disease. In organs at the interface between our body and the environment, the sensory neuropeptide substance P (SP) is one key mediator of an acute local stress response through neurogenic inflammation but may also alter cytokine balance and dendritic cell (DC) function. Using a combined murine allergic inflammation/noise stress model with C57BL/6 mice, we show in this paper that SP—released during repeated stress exposure—has the capacity to markedly attenuate inflammation. In particular, repeated stress exposure prior to allergen sensitization increases DC-nerve fiber contacts, enhances DC migration and maturation, alters cytokine balance, and increases levels of IL-2 and T regulatory cell numbers in local lymph nodes and inflamed tissue in a neurokinin 1-SP-receptor (neurokinin-1 receptor)-dependent manner. Concordantly, allergic inflammation is significantly reduced after repeated stress exposure. We conclude that SP/repeated stress prior to immune activation acts protolerogenically and thereby beneficially in inflammation.
Constipation, IBs and the 5-HT4Receptor: What Role for Prucalopride?
Authors: Sanger Gareth J. , Quigley Eamonn M.M.
Published: December 2010

After the problems associated with the non-selective 5-HT4receptor agonists cisapride and tegaserod, the 5-HT4receptor is now beginning to come in from the cold. Thus, prucalopride is now the first of a new class of drug defined by selectivity and high intrinsic activity at the 5-HT4receptor. Prucalopride has been developed for treatment of chronic constipation rather than constipation-predominant irritable bowel syndrome (IBS). This follows the trend of first evaluating new gastrointestinal (GI) prokinetic drugs in disorders where disrupted GI motility is known to exist, rather than in a functional bowel disorder where changes in motility are uncertain. If prucalopride is not progressed towards the IBS indication, it has at least shown the way for other selective 5-HT4receptor agonists. Most notable among these is TD-5108 (velusetrag), also characterized by good selectivity at the 5-HT4receptor, high intrinsic activity and efficacy in patients with chronic constipation.
Comparison of the Response of the Right Ventricle with Endovascular Occlusion and Surgical Closure in Adults with Atrial Septal Defect One Year after Intervention
Authors: Samiei Niloufar , Bayat Fariba , Moradi Masoud , Parsaei Mozhgan , Haghighi Seyedeh Zahra Ojaghi , Mohebbi Ahmad , Hamzepour Negar , Noohi Fereidoon
Published: December 2010

Background

Use of the Amplatzer septal occluder (ASO) for the closure of secundum atrial septal defect (ASD) has recently become the procedure of choice, while earlier the only treatment for ASD was surgical closure. This study compares the right ventricular indices of the ASO group with the surgical closure group one year after intervention in adults.

Methods

From January 2008 to February 2010, 38 patients with isolated atrial septal defect of the secundum type one year after surgical (n = 20, age = 27 ± 4 years, 13 females, 7 males) or Amplatzer septal occluder closure (n = 18, age = 25 ± 4 years, 12 females, 6 males) were studied. At the same time, thirty-one age-matched normal subjects (age = 26 ± 6 years, 23 females, 9 males) were included as the control group. Strain and strain rate of the right ventricle were measured.

Results

The mean values of strain of the midportion were −26% ± 11.7%, −8.9% ± 4.2%, and 24.5% ± 7.4% ( P < 0.001). Strain rates of the midportion were −2.19 ± 0.6 s−1, −1.2 ± 0.4 s−1, −1.9 ± 0.6 s−1 ( P < 0.001) in ASO, surgery, and control groups, respectively.

Conclusion

This study showed that the right ventricle might show better performance in the ASO than the surgery group in adults with ASD in midterm follow-up.
Comparison of two different sea-salt aerosol schemes as implemented in air quality models applied to the Mediterranean Basin
Authors: Jimenez-Guerrero P. , Jorba O. , Pay M. T. , Montavez J. P. , Jerez S. , Gomez-Navarro J. J. , Baldasano J. M.
Published: December 2010

Abstract. A number of attempts have been made to incorporate sea-salt aerosols (SSA) source functions in chemistry transport models with varying results according to the complexity of the scheme considered. This contribution compares the inclusion of two different SSA algorithms in two chemistry transport models: CMAQ and CHIMERE. The main goal is to examine the differences in average SSA mass and composition and to study the seasonality of the prediction of SSA when applied to the Mediterranean area with high resolution in a reference year. Dry and wet deposition schemes are also analyzed to better understand the differences observed between both models in the target area. The applied emission algorithm in CHIMERE uses a semi-empirical formulation which obtains the surface emission rate of SSA as a function of the surface wind speed cubed and particle size. The emission parameterization included within CMAQ is somehow more sophisticated, since fluxes of SSA are corrected with relative humidity. In order to evaluate their strengths and weaknesses, the participating algorithms as implemented in the chemistry transport models were evaluated against AOD measurements from Aeronet and available surface measurements in Southern Europe and the Mediterranean area, showing biases around −0.003 and −1.2 μg m−3, respectively. The results indicate that both models represent accurately the patterns and dynamics of SSA and its non-uniform behavior in the Mediterranean basin, showing a strong seasonality. The levels of SSA vary strongly across the Western and the Eastern Mediterranean, reproducing CHIMERE higher annual levels in the Aegean Sea (12 μg m−3) and CMAQ in the Gulf of Lion (9 μg m−3). The large difference found for the ratio PM2.5/total SSA in CMAQ and CHIMERE is also investigated. The dry and wet removal rates are very similar for both models despite the different schemes implemented. Dry deposition essentially follows the surface drag stress patterns, meanwhile wet deposition is more scattered over the continent. CMAQ tends to provide larger amounts of SSA dry deposition over the Northern Mediterranean (0.7–1.0 g m−2 yr−1), meanwhile the Southeastern Mediterranean accounts for the maximum annual dry deposition in the CHIMERE model (0.9–1.5 g m−2 yr−1). The wet deposition is dominated by the accumulation mode and is strongly correlated to the precipitation patterns, showing CMAQ a higher wet deposition/total deposition ratio over coastal mountain chains. The results of both models constitute a step towards increasing the understanding of the SSA dynamics in a complex area as the Mediterranean.
Sparse matrix-vector multiplication on network-on-chip
Authors: Sun C.-C. , Götze J. , Jheng H.-Y. , Ruan S.-J.
Published: December 2010

Abstract. In this paper, we present an idea for performing matrix-vector multiplication by using Network-on-Chip (NoC) architecture. In traditional IC design on-chip communications have been designed with dedicated point-to-point interconnections. Therefore, regular local data transfer is the major concept of many parallel implementations. However, when dealing with the parallel implementation of sparse matrix-vector multiplication (SMVM), which is the main step of all iterative algorithms for solving systems of linear equation, the required data transfers depend on the sparsity structure of the matrix and can be extremely irregular. Using the NoC architecture makes it possible to deal with arbitrary structure of the data transfers; i.e. with the irregular structure of the sparse matrices. So far, we have already implemented the proposed SMVM-NoC architecture with the size 4×4 and 5×5 in IEEE 754 single float point precision using FPGA.
Convex programming for detection in structured communication problems
Authors: Morsy T. , Götze J. , Nassar H.
Published: December 2010

Abstract. The generalized Minimum Mean Squared Error (GMMSE) detector has a bit error rate performance, which is similar to the MMSE detector. The advantage of the GMMSE detector is that it does not require the knowledge of the noise power. However, the computational complexity of the GMMSE detector is significantly higher than the computational complexity of the MMSE detector. In this paper, the complexity of the GMMSE detector is reduced by taking into account the structure of the system matrix (Toeplitz). Furthermore, by using circular approximation of the structured system matrix an approximate GMMSE detector is presented, whose computational complexity is only slightly higher than MMSE, i.e.~only an iterative gradient descent algorithm based on the inversion of diagonal matrices is additionally required.
Quantifying sea surface temperature ranges of the Arabian Sea for the past 20 000 years
Authors: Ganssen G. , Peeters F. , Metcalfe B. , Anand P. , Jung S. , Kroon D. , Brummer G.-J.
Published: December 2010

Abstract. The oxygen isotopic composition of planktonic foraminifera tests is one of the widest used geochemical tools to reconstruct past changes of physical parameters of the upper ocean. It is common practice to analyze multiple individuals from a mono-specific population and assume that the outcome reflects a mean value of the environmental conditions during calcification of the analyzed individuals. Here we present the oxygen isotope composition of individual specimens of the surface dwelling species Globigerinoides ruber and Globigerina bulloides from sediment cores in the Western Arabian Sea off Somalia inferred as indicators of past seasonal ranges in temperature. Combining the δ18O measurements of individual specimens to obtain temperature ranges with Mg/Ca based mean calcification temperatures allows us to reconstruct temperature extrema. Our results indicate that over the past 20 kyrs the seasonal temperature range has fluctuated from its present value of 16 °C (14 to 30 °C), to 11 °C (15 to 26 °C) during the LGM. The range during the LGM suggests that the maximum temperature was lower, whilst minimum temperature remained approximately constant.
Application of the HBV hydrological model in a flash flood case in Slovenia
Authors: Grillakis M. G. , Tsanis I. K. , Koutroulis A. G.
Published: December 2010

Abstract. An atmospheric depression passed over northwest Slovenia on 18 September 2007 producing precipitation that exceeded 300 mm/d and a 100-year return period runoff in Zelezniki tributary. The resultant flash flood in the study area, which consisted of five basins, was simulated with the conceptual distributed hydrological model HBV (Hydrologiska Byråns Vattenbalansavdelning). The model was calibrated and validated with past rainfall – runoff events with satisfactory results producing values of Nash – Sutcliffe coefficient between 0.82 and 0.96. The validated model was applied to the flash flood case with stream gauge failure, driven by spatiotemporal precipitation produced by a set of rain gauges and radar data. The model delivered satisfactory results on three out of five basin outlets while the other two had stream gauge failure during the event. The internal basin dynamics of the most affected area in Zelezniki, was successfully tested in eight of its sub-basins by comparing the peak discharges with the ones evaluated by the slope-conveyance method during a detailed intensive post event campaign. The added value of this method is in the reduced uncertainty in peak discharge estimation and event interpretation and in an effective flash flood warning system for the study area when it is combined with radar nowcasts and operational high resolution short range weather forecast models.
Experimental spatial rogue patterns in an optical feedback system
Authors: Odent V. , Taki M. , Louvergneaux E.
Published: December 2010

Abstract. We study pattern formation in an optical system composed of a Kerr medium subjected to optical feedback but in a regime very far from the modulational instability threshold. In this highly nonlinear regime, the dynamics is turbulent and the associated one-dimensional patterns depict rare and intense localized optical peaks. We analyse numerically and experimentally the statistics and features of these intense optical peaks and show that their probability density functions (PDF) have a long tail indicating the occurrence of rogue events.
Governing Equations for Fundamental Aerodynamics
Authors: Anderson John D.
Published: December 2010

The fundamental physical principles that underlie all fluid flow are: (1) mass is conserved; (2) Newton's 2nd Law, F=ma; and (3) energy is conserved. The general equations that mathematically express these principles are; (1) continuity equation; (2) momentum equation; and (3) energy equation. Fluid dynamics can be subdivided into various types of flow; inviscid flows (the transport phenomena of friction, thermal conduction, and diffusion are neglected) for which the flow equations become the Euler equations, and viscous flows (including the transport phenomena) for which the flow equations become the Navier‐Stokes equations. Flows can be further classified as either incompressible or compressible, and rotational or irrotational. A special type of flow, potential flow, is both inviscid and irrotational. Incompressible potential flows are governed by Laplace's equation, and can be synthesized by superposing various elementary flows to obtain more complicated flows. Some elementary flows are uniform flow, source flow and vortex flow. Combinations of these to obtain flow over a circular cylinder are shown. The concept of circulation is given, along with its role in the famous and historic circulation theory of lift. Finally, various flows can be classified under different Mach number regimes – subsonic, transonic, supersonic and hypersonic.
Incompressible Flow Over Finite Wings
Authors: Katz Joseph
Published: December 2010

In this chapter, the aerodynamics of finite wings is analyzed using the classical lifting line model. This simple model allows a closed‐form solution that captures most of the physical effects applicable to finite wings. The model is based on the horseshoe‐shaped vortex that introduces the concept of a vortex wake and wing tip vortices. The downwash induced by the wake creates an induced drag that did not exist in the two‐dimensional analysis. Furthermore, as wingspan is reduced, the wing lift slope decreases, and the induced drag increases, reducing overall efficiency. To complement the high aspect ratio wing case, a slender wing model is formulated so that the lift and drag can be estimated for this limiting case as well. Finally, a brief survey of panel methods is presented. These methods are capable of solving the potential flow over complex (and thick) lifting configurations. The solution, however, can be obtained by using numerical methods only.
ImplicitCFDMethods and Unstructured Grids
Authors: Mavriplis Dimitri J.
Published: December 2010

This chapter provides an overview of the various implicit solution strategies developed for use with unstructured mesh CFD calculations. For time‐dependent simulations, implicit methods are appealing because they enable the use of arbitrarily large time steps, while for steady‐state problems implicit methods are imperative for enabling the practical solution of large problems. The key aspect of implicit solvers on unstructured meshes is the requirement to form and invert a large sparse matrix either directly or approximately. This chapter examines the structure of the implicit matrix and covers various approaches for approximating and inverting the matrix either directly or iteratively. The combination of these basic techniques with other convergence acceleration strategies such as multigrid and Krylov methods is also discussed. The performance of these methods is illustrated through a series of sample calculations.
Thermodynamics
Authors: Borgnakke Claus
Published: December 2010

The basic general laws of thermal science are presented and discussed for the application to finite control volume analyses. These are conservation laws for mass, momentum, and energy and a balance law for entropy. Applications to fixed mass systems and to steady flow devices are shown together with the additional special laws governing the behavior of pure substances as equations of state. Further auxiliary laws are indicated as necessary information from the fields of fluid mechanics and heat transfer. Reversible and irreversible processes are discussed, and limitations imposed by the general laws on processes and device behavior are shown. Special attention is given to the possible work that can be extracted from a proposed system or process as the theoretical limit used as a reference for actual systems. The general theory is used to present an ideal heat engine exemplified by a Carnot cycle and relate that to actual heat engines and their efficiencies.
Gas Turbine Engines: Inlets
Authors: Benson Thomas J. , Seidel Jonathan A.
Published: December 2010

The inlet is the part of the aircraft that brings air into the propulsion system. The inlet design affects the performance of the propulsion system. In turn, the varying airflow demands of the engine affect the performance of the inlet and the flight envelope of the aircraft. A “good” inlet design allows the engine to produce high thrust and low fuel usage over a wide range of flight conditions and throttle conditions. A “poor” inlet design limits the operating range of the engine and aircraft. The chapter discusses the fundamental parameters of performance, compatibility, and integration that characterize an inlet, and then presents some of the recent trends and future directions in inlet design.
Gas Turbine Engines: Nozzles
Authors: DeBonis James R.
Published: December 2010

This chapter describes the exhaust nozzle and its application to aircraft gas turbine engines. The nozzle's two primary functions are to generate thrust and to act as a control valve for the engine. Nozzle performance parameters, discharge coefficient, and thrust coefficient are defined. The basic fluid dynamics and performance of convergent and convergent‐divergent nozzles are discussed. Types of nozzles for subsonic, supersonic, and hypersonic vehicles are described. Secondary nozzle functions thrust reversing, thrust vectoring, noise suppression, and infrared signature suppression are described. Finally nozzle design, analysis, and testing methods are described.
Liquid Propulsion: Engine Production and Operation
Authors: Leahy Joseph C. , Hanna Stephen G. , Malchi Jonathan Y. , Kim Eun S.
Published: December 2010

Launch success involves detailed multi‐disciplined engineering during all phases of a liquid rocket engine – development, production, and operation. The development phase starts with system requirements and involves extensive testing and evaluation to characterize and qualify engine design and operation. Upon completion of development, an engine goes into full‐scale production. Each production engine must meet its requirements within allowable engine‐to‐engine variations, typically during acceptance testing. Every risk must be understood, accepted or mitigated. Numerous reviews, tests and inspections are performed to verify compliance with requirements throughout the entire production process, from component fabrication to vehicle integration. The overall operation of a liquid rocket engine is divided into four distinct stages: (i) start‐up transient, (ii) steady state, (iii) throttling (if throttleable), and (iv) shutdown transient. Start and shutdown transients expose engine components to extreme gradients in operating conditions, while steady‐state and throttling operations occur for a majority of flight and involve fairly moderate changes in operating conditions. This chapter will provide a general overview of the production and operation of liquid rocket engines. Manufacturing and acceptance testing will be discussed as well as vehicle integration and flight operation. Examples of three actual operational engines will also be provided.
Resistojets and Arcjets
Authors: Hoskins Andrew
Published: December 2010

The simplest forms of electrically augmented propulsion for spacecraft are resistance‐heated and arc‐heated thrusters, generally called resistojets and arcjets, respectively. As with all forms of electric propulsion, electric energy added from the spacecraft increases the specific impulse over that achievable with a chemical reaction and expansion through a nozzle. With electrothermal devices, the added energy is imparted to the propellant as thermal energy. In the specific case of the resistojet, energy is added to the propellant with a resistance heater. In the case of an arcjet, an arc is drawn directly through the propellant between a cathode and an anode. The augmented specific impulse is limited by the maximum temperature tolerable by key components over the necessary life of the thruster. The maximum thrust as a function of input electrical power is limited by the efficiency with which the electrical energy is coupled into and contained within the flow and by the efficiency with which the flow enthalpy is converted to axial kinetic energy in the expansion. Resistojets and arcjets have been in development since the late 1950s and have been used on well over 200 spacecraft. This chapter describes the basic construction of these devices, illustrates relationships governing their performance, and surveys the performance demonstrated by a range of laboratory and flight qualified models.
Turbomachinery Aeroelasticity
Authors: Bendiksen Oddvar , Kielb Robert E. , Hall Kenneth C.
Published: December 2010

In this chapter, we describe the range of aeroelastic problems found in modern turbomachinery, and briefly describe the nondimensional parameters that govern these phenomena and the analytical methods used to model them. We classify types of flutter and forced respsone in compressors and fans by location on the compressor map and on the so‐called Campbell diagram. We also present the fundamental equations of motion that govern the aeromechanical behavior of turbomachinery, describe the effect of mistuning on forced response, and give an overview of the computational methods currently used to compute the unsteady aerodynamics associated with the aeroelasticity of turbomachinery.
Thermal Protection Systems (TPSs
Authors: Hurwitz Frances I.
Published: December 2010

Thermal protection systems (TPSs) for space and hypersonic vehicles encompass a wide range of materials and design designs. In any particular vehicle, a variety of materials may be used. The choice of materials and thermal protection concepts is based upon thermal environment and exposure times, as well as whether the application requires single use or multiuse. This chapter provides an overview of materials and concepts, including tile, blankets, metallic systems, structurally integrated concepts, ceramic matrix composites (CMCs), used primarily in hot structures, ultra‐high temperature ceremics (UHTCs), and ablators. It is based upon a review of publicly available literature and includes a historical perspective, as well as some newer developments as of 2009.
Nickel‐Based Superalloys for Blade Application: Production, Performance and Application
Authors: Tin Sammy , Pollock Tresa M.
Published: December 2010

The continuing drive for improvements in the performance, operating temperatures, and emissions in advanced aircraft engines has driven the development of nickel‐based superalloys for decades. Nickel base superalloys are an unusual class of metallic materials with an exceptional combination of high temperature strength, toughness, and resistance to degradation in corrosive or oxidizing environments. Their performance in severe combustion and chemical environments materials has led to their widespread use in aircraft and power generation turbines, rocket engines, nuclear power plant components, marine engines, and a variety of chemical processing operations. Intensive alloy and process development activities over the past few decades have resulted in single crystal Ni‐based superalloys that can tolerate average temperatures of 1050°C with occasional excursions (or local hot spots near airfoil tips) to temperatures as high as 1200°C which is ∼90% of the melting point of the material. The fundamental aspects of the composition and structure that result in these exceptional properties are briefly reviewed. Single crystal Ni‐superalloys that are utilized in gas turbine engines and the advanced manufacturing processes used for their production are outlined along with characteristic mechanical and physical properties.
Active Materials in Aerospace Applications
Authors: Martin Christopher A. , Sater Janet M. , Crowe C. Robert , Obal Michael W.
Published: December 2010

The demonstration and integration of active materials such as electroactive ceramics, shape memory alloys, electroactive polymers, magnetostrictive materials, and electro and magnetorheological fluids into aerospace vehicles has experienced rapid growth in the last two decades. The application and demonstration of active materials and structures has focused on spacecraft, aircraft, and rotorcraft to solve vibration suppression problems and fixed geometry limitations. Illustrative examples of and references for this dynamic and rich area of technology applications are provided.
Corrosion in Space
Authors: de Rooij Antonius
Published: December 2010

The corrosion in space is described by the effect of atomic oxygen on several materials. The metal which was most affected is silver. Silver oxidizes according to a linear‐parabolic law and due to the thermal stresses the oxide layer continuously breaks up, resulting in a linear degradation. Atomic oxygen not only attacks materials in the line of sight of the ram flux, but also by reflected atomic oxygen. Many materials form an adherent oxide layer, such as Cu, Al, and stainless steel and are as such protected once this oxide layer is formed. Some materials have a volatile oxide such as Osmium and many polymers materials. They show a linear behavior.
Takeoff and Landing of Fixed‐Wing Aircraft
Authors: Poole Richard J.
Published: December 2010

This section describes aircraft takeoff and landing maneuvers and the effects of factors such as ambient wind strength and direction involved their execution. Formal requirements of the Western airworthiness authorities for commercial aircraft operations and the necessary safety margins demanded by them are introduced and their interaction with performance scheduling is also addressed. This includes the consideration of the specification of takeoff, landing, acceleration and stopping distances, the accommodation of engine failures, and the specific speeds scheduled when flight planning for these operations. The differing requirements for the operation of naval aircraft from aircraft carriers are presented and the innovative ski‐jump take‐off technique and its performance advantages are described. Special features that allow some aircraft to achieve short take‐off and landing performance are also briefly considered. Finally, simple equations that can be used for trade studies of the various parameters that contribute to take‐off and landing performance are developed and presented.These should not be used for operational flight planning purposes for any particular aircraft.
Fixed‐Wing Lateral and Directional Dynamic Stability
Authors: Lowenberg Mark
Published: December 2010

Stability and control are fundamental properties of an aircraft's dynamic characteristics, influencing flying qualities and hence pilot workload and safety. They are closely linked to other fundamental aspects of aircraft design, including aerodynamics, performance, systems, structure, and operating cost factors. This chapter discusses the governing equations of motion for a rigid‐body aircraft and their linearized form, the latter facilitating the decoupling of lateral–directional stability and control from its longitudinal counterparts for conventional aircraft. The consideration of flight responses in terms of their constituent modes of motion is introduced, using the linear state‐space form of the equations and a stability‐and‐control‐derivative representation of the aerodynamic loads. Thereafter, the stability and response associated with each lateral–directional mode is described in some detail for standard aircraft configurations, with reference to the aerodynamic parameters governing the behavior. The chapter concludes with a brief comment on nonlinearity and how it may modify the linear system stability and control characteristics.
Fly‐by‐Wire Flight Control Systems
Authors: Fielding Chris
Published: December 2010

The early generation of flight control systems were entirely mechanical and used rods and levers, or cables and pulleys, to provide direct mechanical linkages between the pilot's cockpit controls and the control surfaces that maneuver the aircraft. As technologies developed and aircraft evolved in size and speed, the mechanical systems were developed to include fully power‐operated controls. The desire for improved aircraft handling and the need to automate some phases of flight, made it necessary to add signals from the stability augmentation systems and autopilot, to the basic manual control circuits. Eventually, the direct mechanical linkages between the cockpit controls and the actuators were replaced with electrical signalling and computers, leading to the term “fly‐by‐wire”. This arrangement allows the pilot to directly command the aircraft's motion, rather than by commanding the control surface angles needed to achieve the motion. This chapter provides an overview of some of the technologies and processes used for the design and qualification of fly‐by‐wire systems, including aerodynamics and flight control, system hardware and implementation, flight control laws, piloted simulation and aircraft handling, ground and flight testing, the benefits of fly‐by‐wire and future system developments.
Adaptive Control Design Technique for Nonlinear Flight Systems
Authors: Unnikrishnan Nishant , Balakrishnan Sivasubramanya. N.
Published: December 2010

This chapter proposes a new model‐following adaptive control design technique for nonlinear systems that are nonaffine in control. This adaptive controller uses online neural networks that guarantee stability in the presence of unmodeled dynamics (neglected nonlinear terms in the mathematical model) and/or parameter uncertainties present in the system model. In order to ensure stable behavior, an online control adaptation procedure is proposed. The controller design is carried out in two steps:

synthesis of a set of neural networks that capture the unmodeled (neglected) dynamics or model uncertainties due to parametric variations and

synthesis of a controller that drives the state of the actual plant to that of a reference model.

The neural network weight update rule is derived using Lyapunov theory, which guarantees both stability of the error dynamics and boundedness of the weights of the neural networks. This method is tested using a three‐degree‐of‐freedom model of a unmanned aerial vehicle (UAV). Numerical results that demonstrate these features and clearly bring out the potential of the proposed approach are presented in this chapter.
Reconfigurable Flight Control
Authors: Kim Youdan , Kim Sungwan
Published: December 2010

A reconfigurable
flight control system
(
FCS
) is a flight control system that can accommodate the effects of faults by modifying the control system when faults occur during flight. The reconfigurable flight control system provides a significant enhancement to flight safety and performance in the event of a system fault. In this chapter, various approaches for fault tolerant flight control are introduced: passive approaches utilizing robust control schemes and active approaches (control reconfiguration) utilizing
fault detection and diagnosis
(
FDD
), system identification, and adaptive control schemes. The active approach is classified into two methods: a fault detection and diagnosis‐based approach, and an adaptive control‐based approach. In the FDD‐based approach, an efficient and accurate FDD algorithm is required. An appropriate controller is pre‐designed for each fault model, and a switching mechanism is used in selecting the corresponding controller when a particular fault mode is declared by the FDD process. In the adaptive control‐based approach, the FDD process is eliminated to make the fault tolerant control algorithm simple and allow it to adapt quickly to unknown faults. To compensate for the effects of faults in the adaptive control‐based approach,

the changed system parameters due to the faults are estimated or identified online and the controller is adjusted based on the estimated system, or

the changed system model is parameterized in terms of the controller parameters that are directly updated without calculating the plant parameters.
Electro‐optic Sensor Principles
Authors: Richardson Mark A. , James David B.
Published: December 2010

In this chapter the origins and physics of electromagnetic infrared radiation emitted from objects will be presented and discussed; both in terms of the theoretical ideal blackbody, and as applied to more realistic emitters. The wavelength of the emitted radiation is dependent upon the temperature of the object. The suitability of detector systems and configurations will be presented as applied to the detection of objects at different temperatures, and so emitting different wavelengths. Finally, laser action will be explained; covering the origins of laser light, and it's properties which differentiate it from conventional light sources.
Target Tracking
Authors: Ralph Jason F.
Published: December 2010

Radar and electro‐optical systems are used to detect aircraft, missiles, and other vehicles. They measure aspects of the positions and velocities of the objects (targets) that they detect. However, it is only when these measurements are combined to form consistent trajectories or tracks that the sensor can present an intelligible picture of the world around it. Modern target tracking algorithms allow sequences of noisy, erratic measurements to be combined to form reliable tracks. Tracking consists of several stages: measurement‐track association, state estimation, and track creation/deletion. State estimation lies at the heart of all tracking algorithms. It provides accurate estimates of the position and motion of multiple targets and allows their subsequent motion to be predicted, but ancillary track management functions are essential to ensure that the tracks produced are robust and computationally efficient. This section gives an overview of tracking systems and describes how a simple approach (based on linear Kalman and steady‐state filters) can be expanded to deal with more complicated environments and to include advanced algorithms, including nonlinear filters and multiple hypothesis trackers.