bluuebunny/crossref_metadata_2025 huggingface dataset:
Relational autonomy or undue pressure? Family’s role in medical decision‐making
Authors: Ho Anita
Published: February 2008

The intertwining ideas of self‐determination and well‐being have received tremendous support in western bioethics. They have been used to reject medical paternalism and to justify patients’ rights to give informed consent (or refusal) and execute advanced directives. It is frequently argued that everyone is thoroughly unique, and as patients are most knowledgeable of and invested in their own interests, they should be the ones to make voluntary decisions regarding their care. Two results of the strong focus on autonomy are the rejection of the image of patients as passive care recipients and the suspicion against paternalistic influence anyone may have on patients’ decision‐making process. Although the initial focus in western bioethics was on minimizing professional coercion, there has been a steady concern of family’s involvement in adult patients’ medical decision‐making. Many worry that family members may have divergent values and priorities from those of the patients, such that their involvement could counter patients’ autonomy. Those who are heavily involved in competent patients’ decision‐making are often met with suspicion. Patients who defer to their families are sometimes presumed to be acting out of undue pressure. This essay argues for a re‐examination of the notions of autonomy and undue pressure in the contexts of patienthood and relational identity. In particular, it examines the characteristics of families and their role in adult patients’ decision‐making. Building on the feminist conception of the relational self and examining the context of contemporary institutional medicine, this paper argues that family involvement and consideration of family interests can be integral in promoting patients’ overall agency. It argues that, in the absence of abuse and neglect, respect for autonomy and agency requires clinicians to abide by patients’ expressed wishes.
Adjusting to being a father to an infant born prematurely: experiences from Swedish fathers
Authors: Lindberg Birgitta , Axelsson Karin , Öhrling Kerstin
Published: February 2008

The aim of this study was to describe the experiences of being a father to a prematurely born infant. Eight fathers of prematurely born children were interviewed using a narrative approach, and a thematic content analysis was used to analyse the interviews. The fathers described that the preterm birth gave them the chance to get to know their infant as they had to spend time at the intensive care unit. They also felt better educated by professionals who helped them take care of their infant. Their feelings and attachment for their infant increased over time and the fathers felt that they had a stronger bond with their child compared with friends who had babies born at term. As time passed, they became more confident as a father. In spite of the strain, the experience made them change as a person and they expressed having different values. The relationship with their partner was strengthened as they handled this situation together as a couple. However, the fathers felt fortunate despite everything and described having managed a prematurely born infant rather well. Although there are similarities between being a father to a child born at term and to one born preterm, it is significant to gain further knowledge about the specific experiences of fathers of prematurely born infants. The results of this study have implications for nurses working with families who have children born prematurely.
Experiences of the first year as father
Authors: Premberg Åsa , Hellström Anna‐Lena , Berg Marie
Published: February 2008

Background and aims:  The importance of fathers’ participation for development of the child and the well‐being of the family is recognized from earlier research. In Sweden, legislation allows fathers to share the parental leave equally with the mother even so fathers only use a small of their paid leave. The aim of the study was to explore experiences of the first year as a father.

Method:  A phenomenological life world approach was used. Ethical approval was obtained. Ten men, recruited by a purposive sample, were interviewed 12–14 months after the delivery of their first child. The data collection was performed during June and August 2004 in the south‐west area of Sweden.

Findings:  The essence of the experiences of the first year as father was to place the baby in the centre without giving up one’s own person. The child provided warmth and happiness in the family and men experienced a deeper relationship to their partner. The contact between father and child was facilitated by engagement and time spent alone with the child. The major constituents identified from the findings were ‘To be overwhelmed’, ‘To master the new situation’ and ‘To get a new completeness in life’.

Discussion and conclusion:  To master fatherhood maintenance of integrity and possibility to develop an independent relationship with the child is important. Fathers are invited to participate in postnatal childbirth education but the activities address women’s needs and it is doubtful if the fathers benefit from participation. Though fathers entered the delivery room some decades ago, as a support to the woman, health personnel of today must be aware of fathers’ own needs and the impact gender aspects have on their professional support.
A change in life as experienced by first‐time fathers
Authors: Fägerskiöld Astrid
Published: February 2008

Research suggests that the attitude of men towards pregnancy, childbirth and child‐caring is different from that of women. Up to now, research has focused mainly on motherhood. The aim of this study was to explore first‐time fathers’ experiences during early infancy of their children. Grounded theory and constant comparative method were used and 20 fathers aged 20–48 participated. Interviews were carried out in 2002–2003. ‘Changing life’ emerged as the core category consisting of the categories: becoming a father, alternating between work and home, changing relationship towards partner and developing relationship with their child. Changing life implied that they have left bachelor life and become responsible for a child. Becoming a father was much more fantastic than they could have imagined and they suggested that they performed childcare to the same extent as the mother when both parents were at home. Still fathers viewed the mother as the main parent, partly because of their alternating between work and home and because the mothers breast‐feed the infants. Fathers’ attitude towards breast‐feeding seemed to be ambiguous; it was a matter of necessity, but made them feel insignificant. Changing relationship towards partner was common but it was not necessarily for the worst and often resulted in a more closely united relationship. However, tiredness because of lack of sleep could result in increased irritability towards problems. Developing relationship with their child implied increasing possibilities to learn to know the infant’s signals. Fathers are one of two parents, and hence are important for their child’s growth and development, emotional health and cognitive development. Knowledge about first‐time fathers’ experiences during the early infancy of their children may bring about increased support from midwives and child health nurses.
Genes encoding longevity: from model organisms to humans
Authors: Kuningas Maris , Mooijaart Simon P. , Van Heemst Diana , Zwaan Bas J. , Slagboom P. Eline , Westendorp Rudi G. J.
Published: February 2008

Ample evidence from model organisms has indicated that subtle variation in genes can dramatically influence lifespan. The key genes and molecular pathways that have been identified so far encode for metabolism, maintenance and repair mechanisms that minimize age‐related accumulation of permanent damage. Here, we describe the evolutionary conserved genes that are involved in lifespan regulation of model organisms and humans, and explore the reasons of discrepancies that exist between the results found in the various species. In general, the accumulated data have revealed that when moving up the evolutionary ladder, together with an increase of genome complexity, the impact of candidate genes on lifespan becomes smaller. The presence of genetic networks makes it more likely to expect impact of variation in several interacting genes to affect lifespan in humans. Extrapolation of findings from experimental models to humans is further complicated as phenotypes are critically dependent on the setting in which genes are expressed, while laboratory conditions and modern environments are markedly dissimilar. Finally, currently used methodologies may have only little power and validity to reveal genetic variation in the population. In conclusion, although the study of model organisms has revealed potential candidate genetic mechanisms determining aging and lifespan, to what extent they explain variation in human populations is still uncertain.
Acquired temperature‐sensitive paralysis as a biomarker of declining neuronal function in aging Drosophila
Authors: Reenan Robert A. , Rogina Blanka
Published: February 2008

General locomotor activity decreases with normal aging in animals and could be partially explained by decreases in neuronal function. Voltage‐gated Na+ channels are essential in initiating and propagating rapid electrical impulses underlying normal locomotor activity and behavior in animals. Isolation of mutations conferring temperature‐sensitive (ts) paralysis has been an extremely powerful paradigm for identifying genes involved in neuronal functions, such as membrane excitability and synaptic transmission. For instance, decreased expression of wild‐type Na+ channels in flies harboring the no‐action‐potential (nap) mutant allele (mlenapts) confers rapid and reversible ts paralysis, because of failure of action potential propagation. Here, we report that aging wild‐type Drosophila gradually develops an acquired susceptibility to ts paralysis that is indistinguishable from that seen in young ts paralytic mlenapts mutants. Moreover, we show that this general age‐dependent susceptibility is also present in mlenapts flies, although the effects are shifted to lower temperature regimes. The mlenapts flies also exhibit decreased lifespan and increased frailty. Paralysis and decreased lifespan of mlenapts flies were partially rescued by increasing the dosage of para, the structural gene for the major action potential Na+ channel in central nervous system of Drosophila. Lastly, we show a dramatic scaling of ts paralysis susceptibility with chronological age in short‐lived and long‐lived mutant flies, further demonstrating that this age‐dependent risk is independent of genetic background. Thus, decreased neural transmission, a hallmark of which is ts paralysis, is a biomarker of aging.
Discrimination of parasitized aphids by a hoverfly predator: effects on larval performance, foraging, and oviposition behavior
Authors: Almohamad Raki , Verheggen François J. , Francis Frédéric , Hance Thierry , Haubruge Eric
Published: February 2008

The choice of oviposition site by female aphidophagous predators is crucial for offspring performance, especially in hoverflies whose newly hatched larvae are unable to move over large distance. Predator and parasitoid interactions within the aphidophagous guild are likely to be very important in influencing the choices made by predatory hoverfly females. In the present study, the foraging and oviposition behavior of the aphidophagous hoverfly Episyrphus balteatus DeGeer (Diptera: Syrphidae) was investigated with respect to the parasitized state of its aphid prey, Acyrthosiphon pisum Harris (Homoptera: Aphididae), that were parasitized by Aphidius ervi Haliday (Hymenoptera: Aphidiidae). We also recorded the number of eggs laid by hoverfly females when subjected to parasitized aphids. Furthermore, we studied the influence of being fed with parasitized aphids on hoverfly larval performance. Hoverfly females did not exhibit any preference for plants infested with unparasitized or aphids parasitized for 7 days. On the other hand, plants infested with mummies or exuvia were less attractive for E. balteatus. These results were correlated with (i) the number of eggs laid by E. balteatus females and (ii) larval performance. Thus, our results demonstrate that E. balteatus behavior is affected by parasitoid presence through their exploitation of aphid colonies. Indeed, hoverfly predators select their prey according to the developmental state of the parasitoid larvae.
CD20 positive mycosis fungoides: a case report
Authors: Şen Filiz , Kang Steven , Cangiarella Joan , Kamino Hideko , Hymes Kenneth
Published: February 2008

CD20 positive T‐cell lymphoma is extremely rare. Most reported cases are nodal peripheral T‐cell lymphomas (PTCLs) or rarely lymphoma involving extranodal sites. Only two cases of CD20 positive T‐cell lymphomas involving the skin have been previously reported and were classified as PTCL – not otherwise specified. We present a case report of a 53‐year‐old man with CD20 positive mycosis fungoides (MF) involving the skin and an inguinal lymph node. The patient presented with erythematous patches and plaques of the right lower extremity and was found to have an enlarged inguinal lymph node 2 years later. Flow cytometric immunophenotyping of the lymph node aspirate showed a CD2+/CD3+/CD4+/CD5+/CD7−/CD8− T‐cell population with CD20 co‐expression. Molecular studies by polymerase chain reaction demonstrated clonal T‐cell receptor γ chain gene rearrangement. Immunoglobulin heavy and light chain gene rearrangements were not identified. To our knowledge, this is the first case of CD20 positive MF involving a lymph node to be reported in the literature.
Cutaneous and lymphadenopathic Kaposi’s sarcoma: a case report and review of literature
Authors: Hussein Mahmoud R.
Published: February 2008

Kaposi’s sarcoma (KS) of childhood is an extremely rare and unexplained disease. It is usually associated with immunosuppression and human herpes virus 8 (HHV‐8) infection. It can involve skin, mucous membranes, lymph nodes and viscera. This investigation describes a case of a 3‐year‐old boy with cutaneous and lymphangiopathic KS. Initially, the patient presented with cutaneous lesions of KS behind the right ear. Two months later, the disease disseminated not only cutaneously but also to the cervical, axillary and inguinal lymph nodes. Immunological evaluation showed severe lymphocytopenia but without evidence of human immunodeficiency virus infection. The vascular nature of the lesion was supported by positive staining for CD31 and CD34. This study examines the clinicopathologic features of KS in children and summarizes the relevant literature.
Widespread cutaneous metastases from acinic cell carcinoma 20 years after primary presentation
Authors: Varsegi Mary F. , Ravis Scott M. , Hattab Eyas M. , Henley John D. , Billings Steven D.
Published: February 2008

Acinic cell carcinoma is a rare, low‐grade malignant salivary gland neoplasm. Approximately, 20% of patients experience local recurrence and 10% distant metastasis, often many years after initial presentation. We present a case of widespread cutaneous metastasis from acinic cell carcinoma arising in a 59‐year‐old woman with a history of acinic cell carcinoma of the parotid gland 20 years prior to her cutaneous disease. To our knowledge, is the first report of widespread cutaneous metastasis from acinic cell carcinoma.
HPLC COUPLED WITH ION TRAP MS/MS FOR ANALYSIS OF TERTIARY BUTYLHYDROQUINONE IN EDIBLE OIL SAMPLES
Authors: HUANG WEN , NIU HAI , SHI BI , YANG MINLI , JIANG JIXIN
Published: February 2008

A rapid, sensitive, precise and accurate quantitative liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the measurement of tertiary butylhydroquinone (TBHQ) in commercial edible oil was developed and validated. After extraction, samples without prior concentration were analyzed by ion trap MS/MS in MS and MS/MS negative ion detection modes using electrospray ionization. The method showed satisfactory recovery (81.9 ± 1.9–109.6 ± 4.6%), sensitivity (lower limit of quantitation of 48 µg/L for TBHQ) and precision (≤5.2%), as well as excellent linearity (R2 ≥ 0.99), with a run time of only 5 min. The method was successfully applied to the determination of TBHQ in commercial samples of edible oils containing various natural antioxidants, providing a promising and convenient entry to monitor the use of TBHQ.

PRACTICAL APPLICATIONS

HPLC coupled with the ion trap tandem mass spectrometry method with high selectivity, sensitivity, precision and accuracy is suitable for routine quality control analysis of tertiary butylhydroquinone (TBHQ) in edible oils. Analyzing each oil sample by this method takes only 5 min. Moreover, the evaluation of TBHQ in commercial edible oil by this method does not suffer from interference of some coexisting potential peculiar chemical components.
RELATION BETWEEN SENSORY ASTRINGENCY OF EXTRACTS FROM SELECTED TANNIN‐RICH FOODS AND THEIR ANTIOXIDANT ACTIVITY
Authors: AMAROWICZ RYSZARD , TROSZYŃSKA AGNIESZKA , KOSIŃSKA AGNIESZKA , LAMPARSKI GRZEGORZ , SHAHIDI FEREIDOON
Published: February 2008

Extracts obtained from hazelnuts, walnuts, almonds, vetch seeds, buckwheat and buckwheat grits were examined for their sensory astringency and antioxidant properties. The sensory astringency was evaluated using the sensory scaling method and was expressed as sensation of astringency index (SAI). The antioxidant activity of extracts was analyzed using (1) total antioxidant activity (TAA), (2) the ability to scavenge the 2,2‐diphenyl‐1‐picrylhydrazyl radical, (3) bleaching of β‐carotene and (4) reducing power. Human salivary protein (HSP) precipitation capacity of the extracts was assayed by spectrophotometric techniques. Statistically significant correlations (P ≤ 0.05) existed between SAI values and TAA, SAI value and reducing power, and SAI values and HSP precipitation. The presence of condensed tannins in the extracts was confirmed by UV spectral and high‐performance liquid chromatography data.

PRACTICAL APPLICATIONS

The sensory astringency of the tannin‐rich extracts is correlated with their antioxidant activity. This information and the regression equations reported in this study could help to prepare functional foods characterized by the high antioxidant properties that could meet consumer's acceptance. However, studies should continue to explain whether the masking of astringency of plant extract with hydrocolloids may render any undesirable effect on their antioxidant properties.
COMPOSITION, ANTIOXIDATIVE AND OXIDATIVE STABILITY OF MUNGOONG, A SHRIMP EXTRACT PASTE, FROM THE CEPHALOTHORAX OF WHITE SHRIMP
Authors: BINSAN WANWISA , BENJAKUL SOOTTAWAT , VISESSANGUAN WONNOP , ROYTRAKUL SITTIRUK , FAITHONG NANDHSHA , TANAKA MUNEHIKO , KISHIMURA HIDEKI
Published: February 2008

The chemical composition and antioxidative activity of mungoong, a shrimp extract paste from the cephalothorax of white shrimp (Litopenaeus vannamei), were studied. Mungoong contained 42.3% polyunsaturated and 29.59% saturated fatty acid. It was rich in C20:5 n‐3 (eicosapentaenoic acid) (4.31 g/100 g) and C22:6 n‐3 (docosahexaenoic acid) (7.07 g/100 g). Mungoong consisted of Na (15.3 g/kg) and Ca (8.07 g/kg) as the major minerals. Fe and Cu were found at very low content. Glutamine was the most abundant amino acid, while lysine, alanine and asparagine were predominant in mungoong. Mungoong water extract at a level of 1,000 ppm exhibited antioxidative activity in a β‐carotene–linoleic acid, lecithin liposome and comminuted fish model system. Antioxidative potential determined by 2,2‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) and 2,2‐diphenyl‐1‐picrylhydrazyl radical‐scavenging activities and ferric‐reducing antioxidant power was quite stable during 8 weeks of storage at 4C and room temperature (28–30C). Antioxidative activities determined by all assays remained constant within the first week (P > 0.05). Thereafter, only slight decreases in activities were noticeable. During storage at both temperatures, mungoong's 2‐thiobarbituric acid (TBA) values increased during the first 2 weeks of storage (P < 0.05), followed by the gradual decrease of 8 weeks. Nevertheless, no marked changes in TBA values were observed between samples kept at both storage temperatures. Thus, antioxidative peptides might contribute to the retardation of lipid oxidation of mungoong during the extended storage.

PRACTICAL APPLICATIONS

Mungoong, which is an extract paste from the cephalothorax of white shrimp, was demonstrated to be a good source of protein, n‐3 fatty acids as well as minerals. Additionally, mungoong could serve as a novel natural antioxidant with high stability. Therefore, mungoong produced from shrimp‐processing by‐products can be used as a neutraceutical product. This will lead to the full utilization of shrimp‐processing waste and would reduce environmental problems associated with improper disposal of such wastes.
On Nonlinear Forced Vibration of Shrouded Turbine
Blades
Authors: Szwedowicz J. , Visser R. , Sextro W. , Masserey P. A.
Published: February 2008

Numerical predictions of the forced vibration of a disk assembly including frictional effects between the shrouds are presented concerning engineering needs for the blade design process. Assuming a tuned disk assembly, numerical static, free, and then forced vibration analyses of a shrouded turbine blade measured in the spin pit are performed systematically. For the excitation forces of an air jet evaluated from the fairly linear behavior of the experimental blade resonance peaks, the reliability of the proposed approach is validated through the very close agreement of the computed and measured resonant peaks. These resonant peaks demonstrate either a fairly linear behavior or a nonlinear one like the jump effect of blade resonance amplitudes, or elastic impacts between the shrouds. Also, the damping performance for different contact configurations between the shrouds is numerically analyzed. These numerical results indicate that the shrouds generate higher frictional damping for small angles (0–30deg) between the circumferential direction and the normal vector to the contact surface.
Heat Transfer and Pressure Investigation of Dimple Impingement
Authors: Kanokjaruvijit K. , Martinez-Botas R. F.
Published: February 2008

Heat transfer and pressure results of an inline array of round jets impinging on a staggered array of dimples are reported with the consideration of various geometric and parametric effects; results are normalized against flat plate data. The heat transfer was measured by using transient wideband liquid crystal method. The geometrical configurations considered were crossflow (or spent-air exit) scheme, dimple geometries, and impinging positions. Three crossflow schemes were tested such as one-way, two-way, and free exits. These led to the idea of the coupling effects of impingement and channel flow depending on which one dominated. Hemispherical and cusped elliptical dimple shapes with the same wetted area were considered and found that both dimples showed the similarity in heat transfer results. Impinging positions on dimples and on flat portions adjacent to dimples were examined. Throughout the study, the pitch of the nozzle holes was kept constant at four jet diameters. The investigated parameters were Reynolds number (ReDj) ranged from 5000 to 11,500, jet-to-plate spacing (H∕Dj) varied from 1 to 12 jet diameters, dimple depths (d∕Dd) of 0.15, 0.25, and 0.29, and dimple curvature (Dj∕Dd) of 0.25, 0.50, and 1.15. The shallow dimples (d∕Dd=0.15) improved heat transfer significantly by 70% at H∕Dj=2 compared to that of the flat surface, while this value was 30% for the deep ones (d∕Dd=0.25). The improvement also occurred to the moderate and high Dj∕Dd. The total pressure was a function of ReDj and H∕Dj when H∕Dj<2, but it was independent of the target plate geometry. The levels of the total pressure loss of the dimpled plates werenot different from those of the flat surface under the same setup conditions. Wall static pressure was measured by using static taps located across each plate. ReDj and H∕Dj affected the level of the static pressure while the dimple depth influenced the stagnation peaks, and the crossflow scheme affected the shape of the peaks.
Acoustic Response Synthesis Using Multiple Induced-Strain Actuators
Authors: Lin C. C. , Cheng C. C.
Published: February 2008

A methodology to synthesize a predesignated acoustic response using a structure driven by multiple induced-strain actuators, e.g., piezoelectric (PZT) patches, is presented. The proposed approach of solving the inverse problem of structural acoustics, e.g., how to produce a known acoustic response from a given PZT-driven baffled plate, is accomplished using the impedance method. A dynamic model that assembles the PZT patch impedance, the host structure impedance, and the acoustic impedance is developed and then is utilized to synthesize a predesignated acoustic response. The proposed model includes the mass and stiffness of the actuator and thus provides a more accurate prediction when a structure is bonded with multiple actuators.
Implementation of Single and Multiple Adaptive Step-Size Algorithm to ANC
Authors: Sabah Yesim , Okuma Masaaki , Okubo Minoru
Published: February 2008

The purpose of this paper is to investigate a modified adaptive step-size algorithm and implement an active noise control (ANC) system. It is well known that there is a tradeoff between steady state error and convergence rate depending on the step size. This study shows that the new algorithm can track changes in the dynamic characteristics of the ANC system as well as produce a low steady state error. Simulation results are presented to compare the performance of the new algorithm to the basic least mean square (LMS) algorithm. Although there have been several studies of adaptive step-size algorithms, no quantitative analysis has yet been reported for real time active noise control application as far as the authors know. Experimental results are presented for a duct system. The results indicate that the new algorithm provides better performance than the fixed step-size filtered-X least mean square (FXLMS) algorithm.
Three-Component LDV Measurements in the Wake of a Compressor Cascade With Flow Separation
Authors: Hobson G. V. , Caruso T. M. , Carlson J. R.
Published: February 2008

Measurements were taken of the vortex system and turbulent flow that resulted from the interaction between a stator blade and the approaching endwall boundary layer in a linear cascade of compressor blades. Data were taken at a Reynolds number based on blade chord of 640,000. Five-hole pressure measurements were conducted upstream and downstream of the blade row. The approaching boundary layer was also characterized with the laser-Doppler velocimeter. Downstream three-component laser-Doppler velocimetry surveys were conducted at three streamwise stations to map the location and velocity characteristics of the wake and vortex system. Results clearly showed the extent of the vortex emanating from the separation of the boundary layer on the suction side of the blade. Finally, all components of mean flow velocity and turbulence are documented for the last survey station. These data will form a challenging test case for numerical code validation.
Vaneless Diffuser Advanced Model
Authors: Dubitsky Oleg , Japikse David
Published: February 2008

A new vaneless diffuser model is presented. Upon thorough examination of the change in average total pressure, the average static pressure and the average flow angle through a vaneless diffuser, it was discovered that existing models fail to provide useful integrity. Consequently, a new model was built. It was learned that it was necessary to use a two-zone model of the flow entering the vaneless diffuser and to carefully model the two-zone degradation as the flow passes through the vaneless diffuser. The new model is presented with detailed testing. The impact upon future design is outlined, and the expectation is established that various future designs will require the integrity of the new model; old models can be used in limited cases with care.
Dynamic Behavior of Three-Fluid Crossflow Heat Exchangers
Authors: Mishra Manish , Das P. K. , Sarangi Sunil
Published: February 2008

A transient temperature response of three-fluid heat exchangers with finite and large capacitance of the separating sheets is investigated numerically for step, ramp, exponential, and sinusoidal perturbations provided in the central (hot) fluid inlet temperature. The effect of two-dimensional longitudinal conduction in the separating sheet and of axial dispersion in the fluids on the transient response has been investigated. A comparison of the dynamic behavior of four possible arrangements of three-fluid crossflow heat exchangers has also been presented.
Time-Resolved Heat Transfer Measurements on the Tip Wall of a Ribbed Channel Using a Novel Heat Flux Sensor—Part II: Heat Transfer Results
Authors: Jenkins Sean , von Wolfersdorf Jens , Weigand Bernhard , Roediger Tim , Knauss Helmut , Kraemer Ewald
Published: February 2008

Measurements using a novel heat flux sensor were performed in an internal ribbed channel representing the internal cooling passages of a gas turbine blade. These measurements allowed for the characterization of heat transfer turbulence levels and unsteadiness not previously available for internal cooling channels. In the study of heat transfer, often the fluctuations can be equally as important as the mean values for understanding the heat loads in a system. In this study, comparisons are made between the time-averaged values obtained using this sensor and detailed surface measurements using the transient thermal liquid crystal technique. The time-averaged heat flux sensor and transient TLC results showed very good agreement, validating both methods. Time-resolved measurements were also corroborated with hot film measurements at the wall at the location of the sensor to better clarify the influence of unsteadiness in the velocity field at the wall on fluctuations in the heat flux. These measurements resulted in turbulence intensities of the velocity and heat flux of 20%. The velocity and heat flux integral length scales were about 60% and 35% of the channel width, respectively, resulting in a turbulent Prandtl number of 1.7 at the wall.
Experimental Validation of Quasisteady Assumption in Modeling of Unsteady Film-Cooling
Authors: Bernsdorf Stefan , Rose Martin G. , Abhari Reza S.
Published: February 2008

This paper reports on the validation of the assumption of quasisteady behavior of pulsating cooling injection in the near hole flow region. The respective experimental data are taken in a flat plate wind tunnel at ETH Zürich. The facility simulates the film cooling row flow field on the pressure side of a turbine blade. Engine representative nondimensionals are achieved, providing a faithful model at a larger scale. Heating the free stream air and strongly cooling the coolant gives the required density ratio between coolant and free-stream. The coolant is injected with different frequency and amplitude. The three-dimensional velocities are recorded using nonintrusive PIV, and seeding is provided for both air streams. Two different cylindrical hole geometries are studied, with different angles. Blowing ratio is varied over a range to simulate pressure side film cooling. The general flow field, the jet trajectory, and the streamwise circulation are utilized in the validation of the quasisteady assumption.
Response of Viscoelastic Plate to Impact
Authors: Ingman D. , Suzdalnitsky J.
Published: February 2008

Organization of product tests in the microelectronic and optical-electronic industries by the impact method is considered. Two mathematical models: a circular plate under dynamic loading with predetermined initial conditions, and contact interaction of a falling mass and a barrier, are examined. The deflection function, curvature, and acceleration are determined. As the series for these characteristics may prove divergent, the problem is to secure sufficiently reliable results. The method of impact mechanics permits determination of the duration and force of the impact, estimation of the total energy of each mode in the expansion of the deflection function and preclusion of divergent series when determining the plate acceleration and curvature during the vibration process. In parallel, viscoelasticity is simulated with the aid of a fractional-differentiation operator, certain features of which are discussed. Representation of this operator with time-dependent order by ones with constant orders is considered. Three alternative approaches for determination of the eigenfrequency and damping decrement of a vibration process are examined. In particular, a method for calculating these characteristics under conditions of time-dependence and servo control of the order function is proposed.
Active Wave Control of String Near Fixed Boundary
Authors: Saigo Muneharu , Takagi Kiyoshi , Tanaka Nobuo
Published: February 2008

We studied a wave control of a string near a fixed end. The equation of motion of a string is approximated as a lumped-parameter spring-and-mass system using the finite difference method. Finite difference equations (FDEs) for interior node points have the same set of coefficients, whereas the FDEs for boundary node points have a different set of coefficients. By using the control, the latter equation is modified to be as the same equation as the former one. The propagating wave is absorbed through a control actuator as if no boundary existed, and virtually, an infinite system is thus realized. Control is at the string position of the finite difference mesh spacing inside the fixed boundary that is free from supporting loads. We confirmed the effectiveness of the controller by numerical simulation for the traveling string and also did that by numerical simulation and by an experiment for the nontraveling string.
Numerical and Experimental Studies of Gas Pulsations in the Suction Manifold of a Multicylinder Automotive Compressor
Authors: Park Jeong-Il , Bilal Nasir , Adams Douglas E. , Ichikawa Yoshinobu , Bayyouk Jacob
Published: February 2008

This study predicts gas pulsations in the suction manifold of a multicylinder automotive air-conditioning compressor using a comprehensive simulation model of a reciprocating compressor. On the basis of the first law of thermodynamics and a simplified fourth-order Bernoulli-Euler linear differential beam equation for suction valves, the pressure in a cylinder and resultant pressure pulsation in the suction manifold are predicted. The mass flow rate through the valve is estimated assuming one-dimensional compressible flow through an orifice. All of the equations are then solved together in a sequence to obtain the pressure in the cylinder, valve response, and the mass flow rate. A complicated suction manifold geometry is modeled as a simplified cylindrical annular cavity to study gas pulsations in a multicylinder compressor, but the discharge process has not been considered in this study. Using the calculated mass flow rate, pressure pulsations in a simplified cylindrical annular cavity with an area change to consider “mode splitting” are predicted based on the characteristic cylinder method. It is shown that the simulation code can be a useful tool for predicting gas pulsations in the suction manifold of a multicylinder automotive compressor.
Minimizing Maximum Modal Force in Mistuned Bladed Disk Forced Response
Authors: Jones Keith W.
Published: February 2008

Amplitude magnification is defined as the maximum forced response amplitude of any blade on a mistuned bladed disk divided by the maximum response amplitude of any blade on a tuned bladed disk over a range of engine order excitation frequencies. This paper shows that amplitude magnification can be approximated as the maximum ratio of modal force divided by modal vector magnitude in an isolated family of turbine engine bladed disk modes. An infinite linear mistuning pattern, defined by a constant interblade stiffness increment between an infinite number of blades, is found to minimize the maximum modal force when subjected to engine order N/4 excitation. Linear mistuning, an approximation of the infinite linear mistuning pattern, approximately minimizes the maximum modal force for bladed disks with a finite number of blades when subjected to engine order N/4 excitation. From this theory, 2/N is proposed to be a lower boundary for amplitude magnification. The linear mistuning method is demonstrated to produce very low amplitude magnifications numerically and experimentally. The numerical examples suggest that linear mistuning may produce amplitude magnifications near the absolute minimum possible.
Vibratory Parameters of Blades From Coordinate Measurement Machine
Data
Authors: Sinha Alok , Hall Benjamin , Cassenti Brice , Hilbert Gary
Published: February 2008

This paper deals with the development of a procedure to model geometric variations of blades. Specifically, vibratory parameters of blades are extracted from coordinate measurement machine (CMM) data on an integrally bladed rotor (IBR). The method is based on a proper orthogonal decomposition of CMM data, solid modeling, and finite element techniques. In addition to obtaining natural frequencies and mode shapes of each blade on an IBR, statistics of these modal parameters are also computed and characterized. Numerical results are validated by comparison with experimental results.
Improved Diffuser/Volute Combinations for Centrifugal Compressors
Authors: Steglich T. , Kitzinger J. , Seume J. R. , Van den Braembussche R. A. , Prinsier J.
Published: February 2008

Internal volutes have a constant outer radius, slightly larger than the diffuser exit radius, and the circumferential increase of the cross section is accommodated by a decrease of the inner radius. They allow the design of compact radial compressors and hence are very attractive for turbochargers and high-pressure pipeline compressors, where small housing diameters have a favorable impact on weight and cost. Internal volutes, however, have higher losses and lower pressure rise than external ones, in which the center of the cross sections is located at a larger radius than the diffuser exit. This paper focuses on the improvement of the internal volute performance by taking into account the interaction between the diffuser and the volute. Two alternative configurations with enhanced aerodynamic performance are presented. The first one features a novel, nonaxisymmetric diffuser̸internal volute combination. It demonstrates an increased pressure ratio and lower loss over most of the operating range at all rotational speeds compared with a symmetric diffuser̸internal volute combination. The circumferential pressure distortion at off design operation is slightly larger than in the original configuration with a concentric vaneless diffuser. Alternatively, a parallel-walled diffuser with low-solidity vanes and an internal volute allows a reduction of the unsteady load on the impeller and an improved performance, approaching that of a vaneless concentric diffuser with a large external volute.
Numerical Investigation of End Wall Boundary Layer Removal on Highly Loaded Axial Compressor Blade Rows
Authors: Gümmer V. , Goller M. , Swoboda M.
Published: February 2008

This paper presents results of numerical investigations carried out to explore the benefit of end wall boundary layer removal from critical regions of highly loaded axial compressor blade rows. At the loading level of modern aero engine compressors, the performance is primarily determined by three-dimensional (3D) flow phenomena occurring in the end wall regions. Three-dimensional Navier–Stokes simulations were conducted on both a rotor and a stator test case in order to evaluate the basic effects and the practical value of bleeding air from specific locations at the casing end wall. The results of the numerical survey demonstrated substantial benefits of relatively small bleed rates to the local flow field and to the performance of the two blade rows. On the rotor, the boundary layer fluid was removed from the main flow path through an axisymmetric slot in the casing over the rotor tip. This proved to give some control over the tip leakage vortex flow and the associated loss generation. On the stator, the boundary layer fluid was taken from the flow path through a single bleed hole within the passage. Two alternative off-take configurations were evaluated, revealing a large impact of the bleed hole shape and the location on the cross-passage flow and the suction side corner separation. On both blade rows investigated, rotor and stator, the boundary layer removal resulted in a reduction of the local reverse flow, blockage, and losses in the respective near-casing region. This paper gives insight into changes occurring in the 3D passage flow field near the casing and summarizes the effects on the radial matching and pitchwise-averaged performance parameters, namely loss and deviation of the rotor and stator when suction is active. Primary focus is put on the aerodynamics in the blade rows in the main flow path; details of the internal flow structure within the bleed off-take cavities/ports are not discussed here.
Passive Shroud Cooling Concepts for HP Turbines: Experimental Investigations
Authors: Kanjirakkad Vasudevan , Thomas Richard , Hodson Howard , Janke Erik , Haselbach Frank , Whitney Chris
Published: February 2008

The cooling of rotor shrouds in the first stage of a high-pressure turbine requires special attention as flatter turbine inlet temperature profiles and more highly loaded blades result in increased thermal and mechanical stresses. The use of film cooling and/or internal convective cooling makes the rotor shroud heavier and oversized, restricting the maximum rotational speed. Alternative methods are, therefore, sought to achieve improved cooling of the shroud. This paper discusses the low-speed experimental investigation of two “passive” cooling concepts known as “rail cooling” and “platform cooling.” It has been shown experimentally that the modified cooling method, namely, the platform cooling, substantially improves the rotor shroud coolant distribution in the critical areas while employing significantly lower amounts of coolant.
Discussion: “Criteria for Spike Initiated Rotating Stall” (Vo, H. D., Tan, C. S., Greitzer, E. M., 2008, ASME J. Turbomach., 130, p. 011023)
Authors: Deppe A. , Saathoff H. , Stark U.
Published: February 2008

The paper “Criteria for Spike Initiated Rotating Stall” by Vo et al. (2008, ASME J. Turbomach., 130, p. 011023) provides a very important contribution to the understanding of spike-type stall inception in axial-flow compressors by demonstrating that spike-type disturbances are directly linked to the tip leakage flow of the rotor. The computational study of Vo et al. leads to the conclusion that two conditions have to be fulfilled simultaneously for the formation of spike-type stall: (i) axial backflow at the leading edge plane and (ii) axial backflow at the trailing edge plane. The objective of the present technical brief is to support these findings by corresponding experimental results.
Time-Resolved Heat Transfer Measurements on the Tip Wall of a Ribbed Channel Using a Novel Heat Flux Sensor—Part I: Sensor and Benchmarks
Authors: Roediger Tim , Knauss Helmut , Gaisbauer Uwe , Kraemer Ewald , Jenkins Sean , von Wolfersdorf Jens
Published: February 2008

A novel heat flux sensor was tested that allows for time-resolved heat flux measurements in internal ribbed channels related to the study of passages in gas turbine blades. The working principle of the atomic layer thermopile (ALTP) sensor is based on a thermoelectric field created by a temperature gradient over an yttrium-barium-copper-oxide (YBCO) crystal (the transverse Seebeck effect). The sensors very fast frequency response allows for highly time-resolved heat flux measurements up to the 1MHz range. This paper explains the design and working principle of the sensor, as well as the benchmarking of the sensor for several flow conditions. For internal cooling passages, this novel sensor allows for highly accurate, time-resolved measurements of heat transfer coefficients, leading to a greater understanding of the influence of fluctuations in temperature fields.
Numerical Investigation of a Transonic Centrifugal Compressor
Authors: Marconcini Michele , Rubechini Filippo , Arnone Andrea , Ibaraki Seiichi
Published: February 2008

A three-dimensional Navier-Stokes solver is used to investigate the flow field of a high-pressure ratio centrifugal compressor for turbocharger applications. Such a compressor consists of a double-splitter impeller followed by a vaned diffuser. The inlet flow to the open shrouded impeller is transonic, thus giving rise to interactions between shock waves and boundary layers and between shock waves and tip leakage vortices. These interactions generate complex flow structures which are convected and distorted through the impeller blades. Detailed laser Doppler velocimetry flow measurements are available at various cross sections inside the impeller blades highlighting the presence of low-velocity flow regions near the shroud. Particular attention is focused on understanding the physical mechanisms which govern the flow phenomena in the near shroud region. To this end numerical investigations are performed using different tip clearance modelizations and various turbulence models, and their impact on the computed flow field is discussed.
The Influence of Compressor Blade Row Interaction Modeling on Performance Estimates From Time-Accurate, Multistage, Navier–Stokes Simulations
Authors: Van Zante Dale , Chen Jenping , Hathaway Michael , Chriss Randall
Published: February 2008

The time-accurate, multistage, Navier–Stokes, turbomachinery solver TURBO was used to calculate the aeroperformance of a 2 1∕2 stage, highly loaded, high-speed, axial compressor. The goals of the research project were to demonstrate completion times for multistage, time-accurate simulations that are consistent with inclusion in the design process and to assess the influence of differing approaches to modeling the effects of blade row interactions on aeroperformance estimates. Three different simulation setups were used to model blade row interactions: (1) single-passage per blade row with phase lag boundaries, (2) multiple passages per blade row with phase lag boundaries, and (3) a periodic sector (1∕2 annulus sector). The simulations used identical inlet and exit boundary conditions and identical meshes. To add more blade passages to the domain, the single-passage meshes were copied and rotated. This removed any issues of differing mesh topology or mesh density from the following results. The 1∕2 annulus simulation utilizing periodic boundary conditions required an order of magnitude fewer iterations to converge when all three simulations were converged to the same level as assessed by monitoring changes in overall adiabatic efficiency. When using phase lag boundary conditions, the necessity to converge the time history information requires more iterations to obtain the same convergence level. In addition to convergence differences, the three simulations gave different overall performance estimates where the 1∕2 annulus case was 1.0 point lower in adiabatic efficiency than the single-passage phase lag case. The interaction between blade rows in the same frame of reference sets up spatial variations of properties in the circumferential direction, which are stationary in that reference frame. The phase lag boundary condition formulation will not capture this effect because the blade rows are not moving relative to each other. Thus, for simulations of more than two blade rows and strong interactions, a periodic simulation is necessary to estimate the correct aeroperformance.