bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of 12 weeks of block periodization on performance and performance indices in well‐trained cyclists
Authors: Rønnestad B. R. , Ellefsen S. , Nygaard H. , Zacharoff E. E. , Vikmoen O. , Hansen J. , Hallén J.
Published: November 2012

The purpose of this study was to compare the effects of two different methods of organizing endurance training in trained cyclists during a 12‐week preparation period. One group of cyclists performed block periodization (BP; n = 8), wherein every fourth week constituted five sessions of high‐intensity aerobic training (HIT), followed by 3 weeks of one HIT session. Another group performed a more traditional organization (TRAD; n = 7), with 12 weeks of two weekly HIT sessions. The HIT was interspersed with low‐intensity training (LIT) so that similar total volumes of both HIT and LIT were performed in the two groups. BP achieved a larger relative improvement in VO2max than TRAD (8.8 ± 5.9% vs 3.7 ± 2.9%, respectively, P < 0.05) and a tendency toward larger increase in power output at 2 mmol/L [la−] (22 ± 14% vs 10 ± 7%, respectively, P = 0.054). Mean effect size (ES) of the relative improvement in VO2max, power output at 2 mmol/L [la−], hemoglobin mass, and mean power output during 40‐min all‐out trial revealed moderate superior effects of BP compared with TRAD training (ES range was 0.62–1.12). The present study suggests that BP of endurance training has superior effects on several endurance and performance indices compared with TRAD.
Studying the Mechanical Behaviour of Asphalt Mixture with the Grid Method
Authors: Grédiac M. , Toussaint E.
Published: November 2012

Abstract:  The aim of this work is to analyse the strain fields that take place in several asphalt mixture specimens subjected to compression tests. The grid technique is used for this purpose. The main features of this strain measurement technique are first described. The obtained results are then discussed. They show that very strong heterogeneities take place in the strain fields. They are due to the very different mechanical properties of the constituents. Various testing conditions are also investigated because they directly influence the quality of the measurements and the ability of the grid technique to detect small strain amplitudes with a good spatial resolution, this last feature being crucial here because of the very nature of the material under test.
A Promotion Analysis of Wolof Clefts
Authors: Torrence Harold
Published: November 2012

Abstract. This article investigates the syntax of cleft clauses in Wolof. I argue that Wolof clefts are derived by the movement of the clefted constituent to the cleft position. Evidence for the movement anlaysis comes from several general and language‐specific reconstruction tests: island sensitivity, idiom chunk reconstruction, reconstruction for Principle A and Principle C, quantifier binding, negative polarity item reconstruction, and the properties of Wolof subjunctive clauses and clitics. I compare Wolof clefts to English clefts throughout and, following work going back toSchachter 1973, suggest that English clefts are also derived by overt movement of the clefted item. Using quantifier float, clausal pied piping and awh‐copy construction, I argue that movement of the clefted item in Wolof is successive cyclic. Finally, I examine the relation between movement, Superiority, and (Strong and Weak) Crossover by comparing Wolof, English, and Yoruba.
Extensive polymorphism and evidence of selection pressure on major histocompatibility complex DLA‐DRB1, DQA1 and DQB1 class II genes in Croatian grey wolves
Authors: Arbanasić H. , Huber Đ. , Kusak J. , Gomerčić T. , Hrenović J. , Galov A.
Published: November 2012

The genes of the major histocompatibility complex (MHC) are a key component of the mammalian immune system and have become important molecular markers for measuring fitness‐related genetic variation in wildlife populations. Because of human persecution and habitat fragmentation, the grey wolf has become extinct from a large part of Western and Central Europe, and remaining populations have become isolated. In Croatia, the grey wolf population, part of the Dinaric–Balkan population, shrank nearly to extinction during the 20th century, and is now legally protected. Using the cloning–sequencing method, we investigated the genetic diversity and evolutionary history of exon 2 of MHC class II DLA‐DRB1, DQA1 and DQB1 genes in 77 individuals. We identified 13 DRB1, 7 DQA1 and 11 DQB1 highly divergent alleles, and 13 DLA‐DRB1/DQA1/DQB1 haplotypes. Selection analysis comparing the relative rates of non‐synonymous to synonymous mutations (dN/dS) showed evidence of positive selection pressure acting on all three loci. Trans‐species polymorphism was found, suggesting the existence of balancing selection. Evolutionary codon models detected considerable difference between alpha and beta chain gene selection patterns: DRB1 and DQB1 appeared to be under stronger selection pressure, while DQA1 showed signs of moderate selection. Our results suggest that, despite the recent contraction of the Croatian wolf population, genetic variability in selectively maintained immune genes has been preserved.
Oryza sativa actin‐interacting protein 1 is required for rice growth by promoting actin turnover
Authors: Shi Meng , Xie Yurong , Zheng Yiyan , Wang Junmin , Su Yi , Yang Qiuying , Huang Shanjin
Published: November 2012

Rapid actin turnover is essential for numerous actin‐based processes. However, how it is precisely regulated remains poorly understood. Actin‐interacting protein 1 (AIP1) has been shown to be an important factor by acting coordinately with actin‐depolymerizing factor (ADF)/cofilin in promoting actin depolymerization, the rate‐limiting factor in actin turnover. However, the molecular mechanism by which AIP1 promotes actin turnover remains largely unknown in plants. Here, we provide a demonstration that AIP1 promotes actin turnover, which is required for optimal growth of rice plants. Specific down‐regulation of OsAIP1 increased the level of filamentous actin and reduced actin turnover, whereas over‐expression of OsAIP1 induced fragmentation and depolymerization of actin filaments and enhanced actin turnover. In vitro biochemical characterization showed that, although OsAIP1 alone does not affect actin dynamics, it enhances ADF‐mediated actin depolymerization. It also caps the filament barbed end in the presence of ADF, but the capping activity is not required for their coordinated action. Real‐time visualization of single filament dynamics showed that OsAIP1 enhanced ADF‐mediated severing and dissociation of pointed end subunits. Consistent with this, the filament severing frequency and subunit off‐rate were enhanced in OsAIP1 over‐expressors but decreased in RNAi protoplasts. Importantly, OsAIP1 acts coordinately with ADF and profilin to induce massive net actin depolymerization, indicating that AIP1 plays a major role in the turnover of actin, which is required to optimize F‐actin levels in plants.
Nuclear gene targeting in Chlamydomonas using engineered zinc‐finger nucleases
Authors: Sizova Irina , Greiner Andre , Awasthi Mayanka , Kateriya Suneel , Hegemann Peter
Published: November 2012

The unicellular green alga Chlamydomonas reinhardtii is a versatile model for fundamental and biotechnological research. A wide range of tools for genetic manipulation have been developed for this alga, but specific modification of nuclear genes is still not routinely possible. Here, we present a nuclear gene targeting strategy for Chlamydomonas that is based on the application of zinc‐finger nucleases (ZFNs). Our approach includes (i) design of gene‐specific ZFNs using available online tools, (ii) evaluation of the designed ZFNs in a Chlamydomonas in situ model system, (iii) optimization of ZFN activity by modification of the nuclease domain, and (iv) application of the most suitable enzymes for mutagenesis of an endogenous gene. Initially, we designed a set of ZFNs to target the COP3 gene that encodes the light‐activated ion channel channelrhodopsin‐1. To evaluate the designed ZFNs, we constructed a model strain by inserting a non‐functional aminoglycoside 3′‐phosphotransferase VIII (aphVIII) selection marker interspaced with a short COP3 target sequence into the nuclear genome. Upon co‐transformation of this recipient strain with the engineered ZFNs and an aphVIII DNA template, we were able to restore marker activity and select paromomycin‐resistant (Pm‐R) clones with expressing nucleases. Of these Pm‐R clones, 1% also contained a modified COP3 locus. In cases where cells were co‐transformed with a modified COP3 template, the COP3 locus was specifically modified by homologous recombination between COP3 and the supplied template DNA. We anticipate that this ZFN technology will be useful for studying the functions of individual genes in Chlamydomonas.
Genetic and biochemical basis for alternative routes of tocotrienol biosynthesis for enhanced vitaminEantioxidant production
Authors: Zhang Chunyu , Cahoon Rebecca E. , Hunter Sarah C. , Chen Ming , Han Jixiang , Cahoon Edgar B.
Published: November 2012

Vitamin E tocotrienol synthesis in monocots requires homogentisate geranylgeranyl transferase (HGGT), which catalyzes the condensation of homogentisate and the unsaturated C20 isoprenoid geranylgeranyl diphosphate (GGDP). By contrast, vitamin E tocopherol synthesis is mediated by homogentisate phytyltransferase (HPT), which condenses homogentisate and the saturated C20 isoprenoid phytyl diphosphate (PDP). AnHGGT‐independent pathway for tocotrienol synthesis has also been shown to occur by de‐regulation of homogentisate synthesis. In this paper, the basis for this pathway and its impact on vitamin E production when combined withHGGTare explored. An Arabidopsis line was initially developed that accumulates tocotrienols and homogentisate by co‐expression of Arabidopsis hydroxyphenylpyruvate dioxygenase (HPPD) andEscherichia colibi‐functional chorismate mutase/prephenate dehydrogenase (TyrA). When crossed into thevte2–1HPTnull mutant, tocotrienol production was lost, indicating thatHPTcatalyzes tocotrienol synthesis inHPPD/TyrA‐expressing plants by atypical use ofGGDPas a substrate. Consistent with this, recombinant ArabidopsisHPTpreferentially catalyzedin vitroproduction of the tocotrienol precursor geranylgeranyl benzoquinol only when presented with high molar ratios ofGGDP:PDP. In addition, tocotrienol levels were highest in early growth stages inHPPD/TyrA lines, but decreased strongly relative to tocopherols during later growth stages whenPDPis known to accumulate. Collectively, these results indicate thatHPPD/TyrA‐induced tocotrienol production requiresHPTand occurs upon enrichment ofGGDPrelative toPDPin prenyl diphosphate pools. Finally, combined expression ofHPPD/TyrA andHGGTin Arabidopsis leaves and seeds resulted in large additive increases in vitamin E production, indicating that homogentisate concentrations limitHGGT‐catalyzed tocotrienol synthesis.
An unusual case of ocular melanosis and limbal melanocytoma with benign intraorbital extension in a dog
Authors: Dees D. Dustin , MacLaren Nicole E. , Teixeira Leandro , Dubielzig Richard R.
Published: November 2012

This case report describes concurrent ocular melanosis and limbal melanocytoma in a 6‐year‐old Golden Retriever dog. Three years prior, the pet was examined for progressive corneal pigmentation and started on topical Tacrolimus but was subsequently lost to followup. Current ophthalmic examination revealed a large pigmented limbal mass and severe corneal pigmentation of the left eye as well as a small focal raised pigmented mass of the right third eyelid. Due to extent and rapidity of tumor growth, the left eye was removed via transconjunctival enucleation and submitted for histopathologic examination. At the time of surgery, numerous orbital structures including intraorbital fat, extraocular muscles, and portions of the proximal nasolacrimal drainage apparatus contained multifocal areas of black pigmentation. These tissues were subsequently removed and submitted for microscopic analysis. The pigmented mass of the right third eyelid was also excised. Histopathology of the left eye and orbital contents revealed a limbal melanocytoma extending to the bulbar conjunctiva and orbital space forming a large, markedly necrotic mass. Diffuse, severe ocular melanosis, abnormal stromal pigmentation of the sclera and orbital tissues, and corneal stromal pigmentation were noted. The mass of the right third eyelid was confirmed to be a conjunctival melanocytoma. To the authors' knowledge, this is the first report of concurrent ocular melanosis and limbal melanocytoma with orbital infiltration. The peculiar multifocal distribution of melanocytes throughout ocular connective tissues may explain the development of multiple melanocytic lesions in this patient.
Determination of CANDU End Fitting Jacking Limits Using Elastic–Plastic Finite Element Analysis1
Authors: Li Bing , McNeish David , Eom Seyun , Vijay Dk , Lin Si-tsai , Li Jian
Published: November 2012

In one CANDU reactor unit in Ontario, the west end fitting is designed to connect to the end shield via a stop collar. The outboard end of the stop collar is welded to an attachment ring, which shrink-fits on the end fitting body. The east side end fitting is supported by inboard and outboard journal rings resting on their respective bearing sleeves, which allow the “free” axial movement of the channel. In support of some maintenance activities, the west end fitting is required to be jacked to get certain clearance for accommodating the operating tools. The previous elastic calculation got the jacking limit of 8.89 mm, which did not provide enough clearance for tooling. In this paper, an elastic–plastic finite element analysis following ASME B&PV code Section III, Division 1, Subsection NB is performed to increase the jacking limit. The finite element analysis is carried out using ANSYS and validated by an ABAQUS model. In the elastic–plastic finite element analysis, the following effects are considered: strain hardening of stop collar material, stress concentration in stop collar weld, notch effect on stress concentration, and fatigue in stop collar. Cyclic jacking loads as displacement controlled loading are applied in the analysis. Considering the time to the end of unit life, the maximum anticipated end fitting jacking cycles are eight. The higher jacking limit is achieved with an acceptable plastic deformation and fatigue damage at the stop collar, which is the weakest part during the end fitting jacking. The results show that the end fitting can be jacked at west side end-face with 29.7 mm for 1–3 cycles, 29.2 mm for 4 cycles, 26.2 mm for 5 cycles, 24.1 mm for 6 cycles, 21.6 mm for 7 cycles, and 20.3 mm for 8 cycles. The jacking limits achieved in this paper provide enough clearance for the required maintenance operations.
Effects of Pin Detached Space on Heat Transfer in a Rib Roughened Channel
Authors: Siw Sin Chien , Chyu Minking K. , Alvin Mary Anne
Published: November 2012

An experimental study is performed to investigate the heat transfer characteristics and frictional losses in a rib roughened channel combined with detached pin-fins. The overall channel geometry (W = 76.2 mm, E = 25.4 mm) simulates an internal cooling passage of wide aspect ratio (3:1) in a gas turbine airfoil. With a given pin diameter, D = 6.35 mm = [1/4]E, three different pin-fin height-to-diameter ratios, H/D = 4, 3, and 2, were examined. Each of these three cases corresponds to a specific pin array geometry of detachment spacing (C) between the pin-tip and one of the endwalls, i.e., C/D = 0, 1, 2, respectively. The rib height-to-channel height ratio is 0.0625. Two newly proposed cross ribs, namely the broken rib and full rib are evaluated in this effort. The broken ribs are positioned in between two consecutive rows of pin-fins, while the full ribs are fully extended adjacent to the pin-fins. The Reynolds number, based on the hydraulic diameter of the unobstructed cross section and the mean bulk velocity, ranges from 10,000 to 25,000. The experiment employs a hybrid technique based on transient liquid crystal imaging to obtain distributions of the local heat transfer coefficient over all of the participating surfaces, including the endwalls and all pin elements. The presence of ribs enhances local heat transfer coefficient on the endwall substantially by approximately 20% to 50% as compared to the neighboring endwall. In addition, affected by the rib geometry, which is a relatively low profile as compared to the overall height of the channel, the pressure loss seems to be insensitive to the presence of the ribs. However, from the overall heat transfer enhancement standpoint, the baseline cases (without ribs) outperform cases with broken ribs or full ribs.
Numerical and Experimental Investigations of a Compressor Cascade Flow With Secondary Air Removal
Authors: Pönick Sascha , Kožulović Dragan , Radespiel Rolf , Becker Bernd , Gümmer Volker
Published: November 2012

The paper presents numerical and experimental results for a low speed compressor cascade with bleed air removal at the endwall. The aerofoil design is representative for a stator blade in a modern high pressure compressor near the casing wall. Secondary air is commonly supplied by simple bleed geometries downstream of stator rows. The focus of the present investigation was the systematic development of a passage integrated bleed configuration. With the assumption of an invariable bleed mass flow rate it should be designed to provide an advantageous effect on the main flow. Furthermore, a high pressure recovery in the bleed flow was aspired. Steady 3D RANS simulations were performed using the Spalart-Allmaras turbulence model. In both numerical simulations and experiments, an improved performance was found. Beside reduced losses and increased pressure rise, the wake flow downstream of the customized bleed geometry was found to be more homogeneous with decreased deviations due to a favorable influence on the secondary flow.
Coal Ash Deposition on Nozzle Guide Vanes—Part I: Experimental Characteristics of Four Coal Ash Types
Authors: Webb J. , Casaday B. , Barker B. , Bons J. P. , Gledhill A. D. , Padture N. P.
Published: November 2012

An accelerated deposition test facility was operated with four different coal ash species to study the effect of ash composition on deposition rate and spatial distribution. The facility seeds a combusting (natural gas) flow with 10–20 micron mass mean diameter coal ash particulate. The particulate-laden combustor exhaust is accelerated through a rectangular-to-annular transition duct and expands to ambient pressure through a nozzle guide vane annular sector. For the present study, the annular cascade consisted of two CFM56 aero-engine vane doublets, comprising three full passages and two half passages of flow. The inlet Mach number (0.1) and gas temperature (1100 °C) are representative of operating turbines. Ash samples were tested from the three major coal ranks: lignite, subbituminous, and bituminous. Investigations over a range of inlet gas temperatures from 900 °C to 1120 °C showed that deposition increased with temperature, though the threshold for deposition varied with ash type. Deposition levels varied with coal rank, with lignite producing the largest deposits at the lowest temperature. Regions of heightened deposition were noted; the leading edge and pressure surface being particularly implicated. Scanning electron microscopy was used to identify deposit structure. For a limited subset of tests, film cooling was employed at nominal design operating conditions but provided minimal protection in cases of severe deposition.
A Method to Estimate the Performance Map of a Centrifugal Compressor Stage
Authors: Casey Michael , Robinson Chris
Published: November 2012

A novel approach to calculate the performance map of a centrifugal compressor stage is presented. At the design point four nondimensional parameters (the flow coefficient φ, the work coefficient λ, the tip-speed Mach number M, and the efficiency η) characterize the performance. In the new method the performance of the whole map is also based on these four parameters through physically based algebraic equations which require little prior knowledge of the detailed geometry. The variable empirical coefficients in the parameterized equations can be calibrated to match the performance maps of a wide range of stage types, including turbocharger and process compressor impellers with vaned and vaneless diffusers. The examples provided show that the efficiency and the pressure ratio performance maps of turbochargers with vaneless diffusers can be predicted to within ±2% in this way. More uncertainty is present in the prediction of the surge line, as this is very variable from stage to stage. During the preliminary design the method provides a useful reference performance map based on earlier experience for comparison with objectives at different speeds and flows.
Effects of Vortex Generator Application on the Performance of a Compressor Cascade
Authors: Hergt Alexander , Meyer Robert , Engel Karl
Published: November 2012

The performance of a compressor cascade is considerably influenced by secondary flow effects, like the cross flow on the end wall as well as the corner separation between the wall and the vane. An extensive experimental study of vortex generator application in a highly loaded compressor cascade was performed in order to control these effects and enhance the aerodynamic performance. The results of the study will be used in future projects as a basis for parameterization in the design and optimization process for compressors in order to develop novel nonaxisymmetric endwalls as well as for blade modifications. The study includes the investigation of two vortex generator types with different geometrical forms and their application on several positions in the compressor cascade. The investigation includes a detailed description of the secondary flow effects in the compressor cascade, which is based on numerical and experimental results. This gives the basis for a specific approach of influencing the cascade flow by means of vortex generators. Depending on the vortex generator type and position, there is an impact on the end wall cross flow, the development of the horse shoe vortex at the leading edge of the vane, and the extent of the corner separation achieved by improved mixing within the boundary layer. The experiments were carried out on a compressor cascade at a high-speed test facility at DLR in Berlin at minimum loss (design point) and off-design of the cascade at Reynolds numbers up to Re = 0.6 × 106 (based on 40-mm chord) and Mach numbers up to M = 0.7. At the cascade design point, the total pressure losses could be reduced by up to 9% with the vortex generator configuration, whereas the static pressure rise was nearly unaffected. Furthermore, the cascade deflection could be influenced considerably by vortex generators and also an enhancement of the cascade stall range could be achieved. All these results will be presented and discussed with respect to secondary flow mechanisms. Finally, the general application of vortex generators in axial compressors will be discussed.
Experimental Measurements of Ingestion Through Turbine Rim Seals—Part I: Externally Induced Ingress
Authors: Sangan Carl M. , Pountney Oliver J. , Zhou Kunyuan , Wilson Mike , Michael Owen J. , Lock Gary D.
Published: November 2012

This paper describes a new research facility which experimentally models hot gas ingestion into the wheel-space of an axial turbine stage. Measurements of the CO2 gas concentration in the rim-seal region and inside the cavity are used to assess the performance of two generic (though engine-representative) rim-seal geometries in terms of the variation of concentration effectiveness with sealing flow rate. The variation of pressure in the turbine annulus, which governs this externally-induced (EI) ingestion, was obtained from steady pressure measurements downstream of the vanes and near the rim seal upstream of the rotating blades. Although the ingestion through the rim seal is a consequence of an unsteady, three-dimensional flow field and the cause-effect relationship between the pressure and the sealing effectiveness is complex, the experimental data is shown to be successfully calculated by simple effectiveness equations developed from a previously published orifice model. The data illustrate that, for similar turbine-stage velocity triangles, the effectiveness can be correlated using a nondimensional sealing parameter, Φo. In principle, and within the limits of dimensional similitude, these correlations should apply to a geometrically-similar engine at the same operating conditions. Part II of this paper describes an experimental investigation of rotationally-induced (RI) ingress, where there is no mainstream flow and consequently no circumferential variation of external pressure.
Heat Transfer in Turbine Hub Cavities Adjacent to the Main Gas Path
Authors: Dixon Jeffrey A. , Guijarro Valencia Antonio , Bauknecht Andreas , Coren Daniel , Atkins Nick
Published: November 2012

Reliable means of predicting heat transfer in cavities adjacent to the main gas path are increasingly being sought by engineers involved in the design of gas turbines. In this paper, an interim summary of the results of a five-year research program sponsored by the European Union (EU) and several leading gas turbine manufacturers and universities will be presented. Extensive use is made of computational fluid dynamics (CFD) and finite element (FE) modeling techniques to understand the thermo-mechanical behavior of a turbine stator well cavity, including the interaction of cooling air supply with the main annulus gas. The objective of the study has been to provide a means of optimizing the design of such cavities for maintaining a safe environment for critical parts, such as disc rims and blade fixings, while maximizing the turbine efficiency and minimizing the fuel burn and emissions penalties associated with the secondary airflow system. The modeling methods employed have been validated against data gathered from a dedicated two-stage turbine rig running at engine representative conditions. Extensive measurements are available for a range of flow conditions and alternative cooling arrangements. The analysis method has been used to inform a design change, which is also to be tested. Comparisons are provided between the predictions and measurements of the turbine stator well component temperature.
Dimensionless Study on Output Flow Characteristics of Expansion Energy Used Pneumatic Pressure Booster
Authors: Shi Yan , Cai Maolin
Published: November 2012

To obtain high-pressure gas, air-driven boosters are widely used. In this paper, a new pneumatic pressure booster (named expansion energy used booster, short for EEU booster), which makes use of the expansion power of compressed air in driving chambers is proposed. To set a foundation for the study on optimization of the booster, the basic mathematical model of working processes is set up. By selecting the appropriate reference values, the basic mathematical model is transformed to a dimensionless expression for modeling simulation. In this way, the dimensionless output flow characteristics of the booster can also be found. Through analysis, it can be seen that, first, the dimensionless output flow of the booster is mainly determined by the dimensionless Piston Stroke-set (the piston stroke, when the driving chambers stopped to charge air, is defined to be Piston Stroke-set), the dimensionless output pressure of the booster and the dimensionless area of the piston in the driving chambers, the study on optimization of the booster can be done based on the analysis of the influence of the three dimensionless parameters on the dimensionless average output flow and the efficiency. Lastly, the mathematical model is verified experimentally. This research can be referred to in the design of EEU boosters and the study on optimization of the EEU booster.
Iterative Learning in Ballistic Control: Formulation of Spatial Learning Processes for Endpoint Control
Authors: Xu Jian-Xin , Huang Deqing
Published: November 2012

In this paper, we formulate and explore the characteristics of iterative learning in ballistic control problems, where the projectile experiences a constant gravitational force and a fluid drag force that is quadratic in speed. Three scenarios are considered in the spatial learning process, where the shooting speed, shooting angle, or their combination, are, respectively, the manipulated variables. The viewed endpoint displacement is the controlled variable. Under the framework of iterative learning control, ballistic learning convergence is derived in the presence of process uncertainties. In the end, an illustrative example is provided to verify the validity of the proposed ballistic learning control schemes.
Real-Time Implementation and Hardware Testing of a Hybrid Vehicle Energy Management Controller Based on Stochastic Dynamic Programming
Authors: Opila Daniel F. , Wang Xiaoyong , McGee Ryan , Grizzle J. W.
Published: November 2012

An energy management controller based on shortest path stochastic dynamic programming (SP-SDP) is implemented and tested in a prototype vehicle. The controller simultaneously optimizes fuel economy and powertrain activity, namely gear shifts and engine on–off events. Previous work reported on the controller's design and its extensive simulation-based evaluation. This paper focuses on implementation of the controller algorithm in hardware. Practical issues concerning real-time computability, driver perception, and command timing are highlighted and addressed. The SP-SDP controllers are shown to run in real-time, gracefully handle variations in engine start and gear-shift-completion times, and operate in a manner that is transparent to the driver. A hardware problem with the test vehicle restricted its maximum engine torque, which prevented a reliable fuel economy assessment of the SP-SDP controller. The data that were collected indicated that SP-SDP controllers could be straightforwardly designed to operate at different points of the fuel economy tradeoff curve and that their fuel economy may equal or exceed that of a baseline industrial controller designed for the vehicle.
State Estimate-Based Robust Adaptive Control of a Linked Mass-Spring System With Nonlinear Friction
Authors: Wang Yong Fu , Wang Dian Hui , Chai Tian You
Published: November 2012

This paper aims to develop a state estimate-based friction fuzzy modeling and robust adaptive control techniques for controlling a class of multiple degrees of freedom (MDOF) mechanical systems. A fuzzy state estimator is proposed to estimate the state variables for friction modeling. Under some conditions, it is shown that such a state estimator guarantees the uniformly ultimate boundedness (UUB) of the estimate error. Based on system input–output data and our proposed state estimator, a robust adaptive fuzzy output-feedback control scheme is presented to control multiple degrees of freedom system with friction. The adaptive fuzzy output-feedback controller can guarantee the uniformly ultimate boundedness of the tracking error of the closed-loop system. A typical mass-spring system is employed in our simulation studies. The results demonstrate that our proposed techniques in this paper have good potential in controlling nonlinear systems with uncertain friction.
Classification of Two-Phase Flow Patterns by Ultrasonic Sensing
Authors: Jha Devesh K. , Ray Asok , Mukherjee Kushal , Chakraborty Subhadeep
Published: November 2012

This paper presents a methodology for classification of two-phase flow patterns in fluid systems, which takes the measurements of an in situ ultrasonic sensor as inputs. In contrast to the common practice of having an array of ultrasonic detectors, the underlying algorithm requires only a single sensor hardware in combination with an integrated software of signal conditioning, feature extraction, and pattern classification. The proposed method is noninvasive and can be implemented in a variety of industrial applications (e.g., petrochemical processes and nuclear power plants). This concept of flow pattern classification is experimentally validated on a laboratory test apparatus.
A Higher-Order Method for Dynamic Optimization of Controllable Linear Time-Invariant Systems
Authors: Zanotto Damiano , Rosati Giulio , Agrawal Sunil K.
Published: November 2012

This work describes a new procedure for dynamic optimization of controllable linear time-invariant (LTI) systems. Unlike the traditional approach, which results in 2 n first-order differential equations, the method proposed here yields a set of m differential equations, whose highest order is twice the controllability index of the system p. This paper generalizes the approach presented in a previous work to any controllable LTI system.
Evaluating Al2O3 gas diffusion barriers grown directly on Ca films using atomic layer deposition techniques
Authors: Bertrand Jacob A. , George Steven M.
Published: November 2012

Al2O3 gas diffusion barriers grown directly on Ca films using atomic layer deposition (ALD) techniques were evaluated using several methods based on Ca oxidation. The Al2O3 ALD films were grown on Ca films at 120 °C using trimethylaluminum and H2O as the reactants. The oxidation of the Ca films was then monitored versus time at 70 °C and ∼28% relative humidity either by measuring the electrical conductance of the Ca film or by recording the photographic image of the Ca film. In the photographic images, the Ca films revealed that the Al2O3 ALD films have a small number of pinhole defects that lead to Ca film oxidation areas that grow radially around the pinhole defect versus time. A burst of new oxidation areas also appeared suddenly at later times and grew radially versus time. This rapid “blooming” may be related to another type of defect caused by water corrosion of the Al2O3 ALD films. In the electrical conductance measurements, the conductance of the Ca film initially showed little change versus time. The conductance then dropped rapidly when the oxidation area in the photographic image was a noticeable fraction of the Ca film area. The conductance measurements yielded a water vapor transmission rate (WVTR) value of ∼2 × 10−2 g/(m2 day) prior to the rapid reduction of the conductance. The photographic images of the Ca film were also analyzed to obtain a WVTR value assuming radial oxidation of the Ca film around defects. The WVTR values obtained from the electrical conductance and the photographic images were in approximate agreement and increased versus Ca film oxidation until the rapid blooming of new circular oxidation areas. The WVTR values are larger than previous measurements and may indicate that Al2O3 ALD films grown directly on Ca are less stable and degraded by Ca film oxidation. This study reveals that a range of WVTR values can be obtained from different variations of the Ca test depending on the extent of Ca film oxidation.
A modal-based reduction method for sound absorbing porous materials in poro-acoustic finite element models
Authors: Rumpler Romain , Deü Jean-François , Göransson Peter
Published: November 2012

Structural-acoustic finite element models including three-dimensional (3D) modeling of porous media are generally computationally costly. While being the most commonly used predictive tool in the context of noise reduction applications, efficient solution strategies are required. In this work, an original modal reduction technique, involving real-valued modes computed from a classical eigenvalue solver is proposed to reduce the size of the problem associated with the porous media. In the form presented in this contribution, the method is suited for homogeneous porous layers. It is validated on a 1D poro-acoustic academic problem and tested for its performance on a 3D application, using a subdomain decomposition strategy. The performance of the proposed method is estimated in terms of degrees of freedom downsizing, computational time enhancement, as well as matrix sparsity of the reduced system.
Measuring decision weights in recognition experiments with multiple response alternatives: Comparing the correlation and multinomial-logistic-regression methods
Authors: Dai Huanping , Micheyl Christophe
Published: November 2012

Psychophysical “reverse-correlation” methods allow researchers to gain insight into the perceptual representations and decision weighting strategies of individual subjects in perceptual tasks. Although these methods have gained momentum, until recently their development was limited to experiments involving only two response categories. Recently, two approaches for estimating decision weights in m-alternative experiments have been put forward. One approach extends the two-category correlation method to m > 2 alternatives; the second uses multinomial logistic regression (MLR). In this article, the relative merits of the two methods are discussed, and the issues of convergence and statistical efficiency of the methods are evaluated quantitatively using Monte Carlo simulations. The results indicate that, for a range of values of the number of trials, the estimated weighting patterns are closer to their asymptotic values for the correlation method than for the MLR method. Moreover, for the MLR method, weight estimates for different stimulus components can exhibit strong correlations, making the analysis and interpretation of measured weighting patterns less straightforward than for the correlation method. These and other advantages of the correlation method, which include computational simplicity and a close relationship to other well-established psychophysical reverse-correlation methods, make it an attractive tool to uncover decision strategies in m-alternative experiments.
Growth of suppression using distortion-product otoacoustic emission measurements in hearing-impaired humans
Authors: Birkholz Cori , Gruhlke Alyson , Neely Stephen T. , Kopun Judy , Tan Hongyang , Jesteadt Walt , Schmid Kendra K. , Gorga Michael P.
Published: November 2012

Growth of distortion-product otoacoustic emission suppression was measured in 65 subjects with mild-to-moderate sensorineural hearing loss (HI). Measurements were made at four probe frequencies (f2) and up to five L2 levels. Eleven suppressor frequencies (f3) were used for each f2, L2 combination. These data were compared to data from normal-hearing (NH) subjects (Gorga et al., 2011a). In both NH and HI subjects, growth of suppression depended on the relation between f2 and f3, such that the slope was close to one when f3 ≈ f2, steeper than one when f3 < f2, and shallower than one when f3 > f2. Differences in growth of suppression between NH and HI subjects were not observed for fixed f2, L2 combinations, however large differences were observed in suppressor “threshold” when compared at the same probe sensation level (dB SL). Smaller group differences were observed when compared at the same probe sound-pressure level (dB SPL). Therefore, the extent of these differences depended on how probe level (L2) was specified. When the results from NH and HI subjects are compared with each other and with psychophysical studies of masking, differences are observed that have implications for the remediation of mild-to-moderate hearing loss.
Investigating the auditory enhancement phenomenon using behavioral temporal masking patterns
Authors: Shen Yi , Richards Virginia M.
Published: November 2012

A narrowband signal is subjected to less masking from a simultaneously presented notched masker if it is preceded by a precursor that occupies the same spectral region as the masker, a phenomenon referred to as enhancement. The present study investigated (i) the amount of enhancement for the detection of a narrowband noise added to a notched masker, and (ii) masking patterns associated with the detection of tone pips added to the narrowband signal. The resulting psychophysical data were compared to predictions generated using a model similar to the neural adaptation-of-inhibition model proposed by Nelson and Young [(2010b). J. Neurosci. 30, 6577–6587]. The amount of enhancement was measured as a function of the temporal separation between the precursor and masker in Experiment I, and as a function of precursor level in Experiment II. The model captured the temporal dynamics of psychophysical enhancement reasonably well for both the long-duration noise signals and the masking patterns. However, in contrast to psychophysical data which indicated reliable enhancement only when the precursor and masker shared the same levels, the model predicated enhancement at all precursor levels.
Bayesian space-frequency separation of wide-band sound sources by a hierarchical approach
Authors: Zhang Erliang , Antoni Jérôme , Dong Bin , Snoussi Hichem
Published: November 2012

This paper proposes an efficient solution to the separation of uncorrelated wide-band sound sources which overlap each other in both space and frequency domains. The space-frequency separation is solved in a hierarchical way by (1) expanding the sound sources onto a set of spatial basis functions whose coefficients become the unknowns of the problem (backpropagation step) and (2) blindly demixing the coefficients of the spatial basis into uncorrelated components relating to sources of distinct physical origins (separation step). The backpropagation and separation steps are both investigated from a Bayesian perspective. In particular, Markov Chain Monte Carlo sampling is advocated to obtain Bayesian estimates of the separated sources. Separation is guaranteed for sound sources having different power spectra and sufficiently smooth spatial modes with respect to frequency. The validity and efficiency of the proposed separation procedure are demonstrated on laboratory experiments.
Vibratory responses of synthetic, self-oscillating vocal fold models
Authors: Murray Preston R. , Thomson Scott L.
Published: November 2012

The flow-induced responses of four self-oscillating synthetic vocal fold models are compared. All models were life-sized and fabricated using flexible silicone compounds with material properties comparable to those of human vocal fold tissue. Three of the models had two layers of different stiffness to represent the body–cover grouping of vocal fold tissue. Two of the two-layer models were based on the “M5” geometry [Scherer et al., J. Acoust. Soc. Am. 109, 1616–1630 (2001)], while the third was based on magnetic resonance imaging data. The fourth model included several layers, including a thin epithelial layer, an exceedingly flexible superficial lamina propria layer, a ligament layer that included an anteriorly–posteriorly oriented fiber to restrict vertical motion, and a body layer. Measurements were performed with these models in full larynx and hemilarynx configurations. Data included onset pressure, vibration frequency, glottal flow rate, maximum glottal width, and medial surface motion, the latter two of which were acquired using high-speed imaging techniques. The fourth, multi-layer model exhibited onset pressure, frequency, and medial surface motion traits that are comparable to published human vocal fold data. Importantly, the model featured an alternating convergent–divergent glottal profile and mucosal wave-like motion, characteristics which are important markers of human vocal fold vibration.
Implementation of diffraction in a ray-tracing model for the prediction of noise in open-plan offices
Authors: Chevret P. , Chatillon J.
Published: November 2012

Sound prediction in open-plan offices is a real challenge because of the complexity of the layout of such offices, and therefore because of the multitude of acoustic phenomena involved. One such phenomenon, of primary importance, and not the least challenging of them, is the diffraction by screens and low dividers that usually partition the workspace. This paper describes implementing the equations of the Uniform Theory of Diffraction [McNamara et al. (1990). Introduction to the Uniform Theory of Diffraction (Artech House, Boston)] in an existing ray-tracing model initially dedicated to sound prediction in industrial premises. For the purposes of validation, a series of measurements was conducted in a semi-anechoic chamber in the same manner as Wang and Bradley [(2002). Appl. Acoust. 63, 849–866] but including real desktops instead of single screens. A first phase was dedicated to controlling the quality of the installation by making comparisons with McNamara's solution for a single screen on a rigid floor. Then, the validation itself was conducted with measurements on real desktops, first without a ceiling, and then with a rigid ceiling suspended above the double desk. The results of the comparisons between calculations and measurements in this configuration have demonstrated that the model is an effective tool for predicting sound levels in an open-plan office.
Cross-correlations of diffuse noise in an ocean environment using eigenvalue based statistical inference
Authors: Menon Ravishankar , Gerstoft Peter , Hodgkiss William S.
Published: November 2012

Cross-correlations of diffuse noise fields can be used to extract environmental information. The influence of directional sources (usually ships) often results in a bias of the travel time estimates obtained from the cross-correlations. Using an array of sensors, insights from random matrix theory on the behavior of the eigenvalues of the sample covariance matrix (SCM) in an isotropic noise field are used to isolate the diffuse noise component from the directional sources. A sequential hypothesis testing of the eigenvalues of the SCM reveals eigenvalues dominated by loud sources that are statistical outliers for the assumed diffuse noise model. Travel times obtained from cross-correlations using only the diffuse noise component (i.e., by discarding or attenuating the outliers) converge to the predicted travel times based on the known array sensor spacing and measured sound speed at the site and are stable temporally (i.e., unbiased estimates). Data from the Shallow Water 2006 experiment demonstrates the effectiveness of this approach and that the signal-to-noise ratio builds up as the square root of time, as predicted by theory.
Acoustics of fish shelters: Frequency response and gain properties
Authors: Lugli Marco
Published: November 2012

Many teleosts emit sounds from cavities beneath stones and other types of submerged objects, yet the acoustical properties of fish shelters are virtually unexplored. This study examines the gain properties of shelters commonly used by Mediterranean gobies as hiding places and/or nest sites in the field (flat stones, shells belonging to five bivalve species), or within aquarium tanks (tunnel-shaped plastic covers, concrete blocks, concrete cylinder pipe, halves of terracotta flower pots). All shelters were acoustically stimulated using a small underwater buzzer, placed inside or around the shelter to mimic a fish calling from the nest site, and different types of driving stimuli (white noise, pure tones, and artificial pulse trains). Results showed the presence of significant amplitude gain (3–18 dB) at frequencies in the range 100–150 Hz in all types of natural shelters but one (Mytilus), terracotta flower pots, and concrete blocks. Gain was higher for stones and artificial shelters than for shells. Gain peak amplitude increased with the weight of stones and shells. Conclusions were verified by performing analogous acoustical tests on flat stones in the stream. Results draw attention to the use of suitable shelters for proper recording of sounds produced by fishes kept within laboratory aquaria.