bluuebunny/crossref_metadata_2025 huggingface dataset:
Pure Hypertriglyceridemia Might be Associated with Erectile Dysfunction: A Pilot Study
Authors: Heruti Rafi , Arbel Yaron , Steinvil Arie , Zarka Salman , Saar Nili , Kinori Michael , Brenner Galit , Justo Dan
Published: February 2008

Introduction

Unlike the association between erectile dysfunction (ED) and high levels of low-density lipoprotein (LDL) cholesterol, the association between ED and hypertriglyceridemia is still debatable.

Aim

To study prevalence and severity of ED in young men with very high levels of triglycerides.

Main Outcome Measures

Prevalence of ED, ED severity, total cholesterol levels, LDL cholesterol levels, and triglycerides levels.

Methods

Men who were enrolled went through routine health checks including full lipid profiling and completion of the Sexual Health Inventory for Men (SHIM) questionnaire. Very high levels of triglycerides were defined as ≥500 mg/dL. Very high levels of LDL cholesterol were defined as ≥190 mg/dL. Men with diabetes, ischemic heart disease, high-density lipoprotein (HDL) cholesterol ≥60 mg/dL, and mixed hyperlipidemias were excluded.

Results

Included were 88 men, aged 35.9 ± 7.1 years (range: 25–51 years): 21 men with “pure” severe hypertriglyceridemia (triglyceride levels ≥500 mg/dL and non-HDL cholesterol ≤189 mg/dL), 34 men with “pure” severe hyperlipidemia (LDL cholesterol levels ≥190 mg/dL and triglycerides ≤199 mg/dL), and 33 men with normal cholesterol levels. No significant differences were found between these groups in terms of mean age and mean SHIM score. Prevalence of ED (i.e., SHIM score < 22) was higher among men with “pure” severe hypertriglyceridemia than among men with “pure” severe hyperlipidemia (42.9% vs. 29.4%) and men with normal cholesterol levels (42.9% vs. 24.2%), although these results were not statistically significant (P = 0.2 and 0.4, respectively).

Conclusions

Conclusions. Prevalence of ED might be increased in young men with “pure” severe hypertriglyceridemia, though a larger cohort with a longitudinal follow-up is needed to prove that hypertriglyceridemia is an independent risk factor for ED.
Penile Fracture: Surgical Repair and Late Effects on Erectile Function
Authors: Ateyah Ahmed , Mostafa Taymour , Nasser Taha Abdel , Shaeer Osama , Hadi Ahmed Abdel , Al-Gabbar Mohammed Abd
Published: February 2008

Introduction

Penile fracture is described as a traumatic rupture of the tunica albuginea because of blunt injury of an erect penis.

Aim

To assess the etiology, treatment maneuvers, and late effects of penile fractures treated by surgical repair.

Methods

Thirty-three patients diagnosed provisionally as having fractured penises. Thirty patients were managed by immediate surgical repair and three by delayed repair.

Main Outcome Measures

International Index of Erectile Function-5 for married cases and Single-question Self-report of Erectile Dysfunction questionnaires and recording complications after 2, 3, and 6 months.

Results

The most common cause of fracture penis is self-inflicted acute bending (54.5%). The tear was visualized by ultrasound in 20/30 patients (66.7%) mostly on the right proximal third of the penis. All tears were unilateral with mean length 2.0 ± 0.9 cm (range 0.5–4 cm). All patients who completed their follow-up after 6 months (N=24) were able to achieve an adequate erection except two married cases who felt mild erectile dysfunction. Penile nodules were the most common postoperative complication (41.7%) after 6 months' follow-up. Patients treated with immediate or delayed repair had comparable complications.

Conclusions

Fracture penis is not uncommon as an emergency that must be repaired either immediately or delayed. Clinical diagnosis is more predictive than ultrasound in diagnosis and determining the site of the tear. Ultrasound may be of value in patients where there is clinical doubt.
Helium stratification in HD145792: a new helium strong star
Authors: Catanzaro G.
Published: February 2008

In this Letter, we report on the real nature of the star HD 145792, classified as He weak in ‘The General Catalogue of Ap and Am stars’. By means of FEROS@ESO 1.52m high-resolution spectroscopic data, we refined the atmospheric parameters of the star, obtaining: Teff= 14 400 ± 400 K, log g= 4.06 ± 0.08 and ξ= 0+0.6 km s−1. These values resulted always lower than those derived by different authors with pure photometric approaches.

Using our values, we undertook an abundance analysis with the aim to derive, for the first time, the chemical pattern of the star's atmosphere. For metals, a pure local thermodynamic equilibrium synthesis (atlas9 and synthe) has been used, while for helium a hybrid approach has been preferred (atlas9 and synspec). The principal result of our study is that HD 145792 belongs to He-strong class contrary to the previous classification. Moreover, helium seems to be vertically stratified in the atmosphere, decreasing towards deepest layers.

For what that concerns metal abundances, we found the following: overabundance of oxygen, neon, silicon, phosphorus, sulphur and calcium; carbon, nitrogen, magnesium, aluminum, titanium, chromium and nickel are normal, being the discrepancies from the solar values within the experimental errors; iron resulted to be slightly underabundant.
PHYSICOCHEMICAL PROPERTIES OF CUCUMIS MELO VAR. INODORUS (HONEYDEW MELON) SEED AND SEED OIL
Authors: YANTY N.A.M. , LAI O.M. , OSMAN A. , LONG K. , GHAZALI H.M.
Published: February 2008

Cucumis melo var. inodorus seeds were found to contain 4.5% moisture, 25.0% crude fat, 25.0% crude protein, 23.3% crude fiber, 2.4% ash and 19.8% carbohydrate. The iodine and saponification values, and unsaponifiable matter and free fatty acid contents of freshly extracted honeydew melon seed oil were 153.4 g I2/100 g oil, 210.2 mg KOH/g oil, 0.9 and 2.5%, respectively. The oil had a color index of 1.6Y + 0.4R, and had 10 fatty acids, of which 86.1% were unsaturated. Linoleic acid predominated with 69.0% followed by oleic acid (16.8%) and palmitic acid (8.4%). LLL (24.9%), OLL (21.5%), PLL (15.9%) and POL (12.4%) (where L, O, P and S denote linoleic, oleic, palmitic and stearic acids, respectively) were the major triacylglycerols present. The melting and crystallization temperatures were −5.12 and −59.01C, respectively. Electronic nose analysis showed the presence of more volatile compounds compared to refined sunflower oil, an oil rich also in linoleic acid.

PRACTICAL APPLICATIONS

In Malaysia, honeydew melon (Cucumis melo var. inodorus) seeds are normally treated as waste products. In this study, honeydew melon seed oil was found to have a potential to become a new edible oil source as it contained a level high in polyunsaturated fatty acids.
LIPID CLASS COMPOSITIONS, TOCOPHEROLS AND STEROLS OF TREE NUT OILS EXTRACTED WITH DIFFERENT SOLVENTS
Authors: MIRALIAKBARI HOMAN , SHAHIDI FEREIDOON
Published: February 2008

The chemical compositions of tree nut oils were examined. The oils of almonds, Brazil nuts, hazelnuts, pecans, pine nuts, pistachios and walnuts were extracted using hexane and chloroform/methanol. The chloroform/methanol system afforded a higher oil yield for each tree nut type examined (pine nuts had the highest oil content while almonds had the lowest). The lipid class compositions of the tree nut oils were analyzed using the thin‐layer chromatography‐flame ionization detector and showed that triacylglycerols were the predominant lipid class present. Smaller amounts of sterols, sterol esters, phospholipids and sphingolipids were also present. The fatty acid compositions of the tree nut oils were analyzed using gas chromatography, showing that oleic acid was the predominant fatty acid in all samples except pine nut and walnut oils, which contained high amounts of linoleic acid. The sterol and stanol content and compositions were analyzed using gas chromatography; β‐sitosterol was the predominant sterol present in all samples, with lower amounts of campesterol, stigmasterol, Δ5‐avenasterol, 22‐nordehydrocholesterol, 24‐methylenecholesterol, cholesterol, cholestanol and β‐sitostanol also present. The tocopherol compositions were analyzed using high‐performance liquid chromatography, showing that α‐ and γ‐tocopherols were the predominant tocopherol homologs present; however, δ‐ and β‐tocopherols were also detected in some samples.

PRACTICAL APPLICATIONS

Tree nut oils contain health‐promoting unsaturated fatty acids and minor components that may render beneficial effects. The lipid class compositions of the oils are reported as these affect the stability of the tested oils. Results may have significance in terms of practical applications for food and use in nutraceutical and/or cosmoceuticals products.
ANTIOXIDANT ACTIVITY OF EXTRACT OF ADZUKI BEAN AND ITS FRACTIONS
Authors: AMAROWICZ RYSZARD , ESTRELLA ISABEL , HERNÁNDEZ TERESA , TROSZYŃSKA AGNIESZKA
Published: February 2008

Phenolic compounds were extracted from adzuki bean using 80% (v/v) aqueous acetone. Crude extract was applied onto a Sephadex LH‐20 column. Fraction I, consisting of low‐molecular‐weight phenolics, was eluted from the column using ethanol. Fraction II, consisting of tannins, was obtained using water/acetone (1:1; v/v) as the mobile phase. Phenolic compounds present in the crude extract and its fractions showed antioxidant and radical scavenging properties as revealed using a β‐carotene‐linoleate model system, the total antioxidant activity (TAA) method, the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging activity and reducing power evaluation. Results of these assays showed highest values when tannins (fraction II) were tested. For example, the TAA of the tannin fraction was 4.17 µmol Trolox/mg, whereas extract and fraction I showed 1.76 and 1.40 µmol Trolox/mg, respectively. The content of total phenolics in fraction II was the highest (189 mg/g). The content of tannins in this fraction determined using the vanillin method and expressed as absorbance units at 500 nm/1 g was 213. There were 29 compounds (hydroxycinnamics, procyanidins, gallates, flavonols, dihydroflavonols, dihydrochalcones) identified in the crude extract using a high‐performance liquid chromatography with photodiode array and mass spectrometry detectors (HPLC‐PAD‐MS) method. Catechin and epicatechin glucosides, procyanidin dimers, myricetin and protocatechuic acid were the dominant phenolics in the extract.

PRACTICAL APPLICATIONS

Results showing the antioxidant activity of adzuki bean extract and its fraction can be useful for producers of healthy foods. The tannin fraction separated from adzuki can be applied for production of natural antioxidant preparations. The results of chemical analysis are valuable for databases of food phenolic compounds.
Natural activity: an explorative study of the interplay between cage‐birds and older people in a Swedish hospital setting
Authors: Falk Hanna , Wijk Helle
Published: February 2008

Aim.  The aim of this study was to describe the interaction between cage‐birds and older people as it arises in spontaneous situations in a Swedish hospital ward setting.

Background.  Older people are at risk of being affected by mental fatigue because of various age‐related reductions and disease. Mental fatigue manifests itself through a reduced ability to concentrate. The method of alleviating mental fatigue with the use of stimulating natural settings or animal‐assisted activities is so far unexplored in Sweden and subsequently it is important to study the method in a Swedish context to implement it as a recognized nursing intervention in the care of older people.

Design.  The study had an explorative observational design, and was conducted at a geriatric ward with a consecutive selection of participants.

Method.  The observations were analysed using a constant comparative method influenced by Grounded Theory. ‘Attention restorative theory’ was used as the theoretical framework to guide the study.

Result.  Our findings indicate that animal‐assisted therapy has a positive effect on involuntary attention and mental restoration, as well as on enhanced social behaviour among older people.

Relevance to clinical practice.  The result strengthens the assumption that animal companionship should be considered a beneficial nursing intervention for older people to prevent mental fatigue.
Unmet expectations: why nursing home staff leave care work
Authors: Fläckman Birgitta , Sørlie Venke , Kihlgren Mona
Published: February 2008

Background. The shortages of healthcare professionals have been a common topic in care of older people.

Aim and objectives. The aim of the present study was to illuminate what caused the nursing home caregivers to decide to leave their employment.

Design. A two‐year intervention study was performed in three nursing homes in Sweden.

Method. This qualitative interview study was conducted with 18 caregivers who decided to leave their employment during the first year. Content analysis was the method used to analyse the interviews.

Result. The caregivers' decisions to leave their work in care of older people could be encompassed in one main category: ‘Unmet Expectations’. Their experiences were lack of encouragement and trust and professional development. Feelings of insecurity, different opinions on the care delivered, being disregarded and betrayed followed as did thoughts of leaving work and pursing other opportunities.

Conclusion. The main findings indicated that organizational work pressure with information about pending financial cutbacks caused the caregivers to leave the nursing homes.

Relevance to clinical practice. The study's results show the value of meeting the needs of caregivers, as caregivers consider that they meet the needs of the older people. Optimal use of caregivers' skills, experiences, competence and respect for their aspirations is also likely to result in cost‐efficient care.
Shielding or caging? Healthcare staffs’ views on fall risk and protection in Stockholm
Authors: Fonad Edit , Burnard Philip , Emami Azita
Published: February 2008

Aim.  To describe Registered Nurses’ and enrolled nurses’ views and reasoning on falls, fall risk, use of physical restraints and patients’ safety and security in nursing homes.

Background.  Nursing home patients frequently suffer from diseases which require medication. Both Registered Nurses and enrolled nurses must make decisions about how to protect patients from falls and fall‐related injuries. Physical restraints are frequently used. When patients are unable to understand or do not wish to limit their freedom of movement, staff must consider each decision carefully.

Method.  A qualitative approach was used. Data were analysed using a thematic content analysis method.

Findings.  Staff have sufficient knowledge about which pathologically related conditions lead to fall risk. An insufficient number of staff on duty jeopardizes patient safety. Wheelchairs with safety belts, and bed rails, are sometimes used. For Registered Nurses it was not an easy decision to use restraints. Enrolled nurses’ actions were based on standard procedure, to protect and supervise patients.

Conclusion.  Staff often use restraints to protect their patients, even though this may mean compromising the patient’s integrity.

Relevance to clinical practice.  Nurses, occupational therapists, physiotherapists and physicians should plan the care together. Restrictive measures should be adapted to each individual patient.
Prognostic irrelevance of HLA‐G in B‐cell chronic lymphocytic leukemia
Authors: PEREZ‐CHACON G. , ROSADO S. , REBOLLEDA N. , LOSADA‐FERNANDEZ I. , VARGAS J. A. , MORADO M. , JORDA J. , PEREZ‐ACIEGO P.
Published: February 2008

In the last few years, it has been suggested that the involvement of human leukocyte antigen‐G (HLA‐G) in several tumoral processes and its likely participation as a factor of immune tolerance in malignant cells. Recently, positive HLA‐G surface expression has been associated with a poor prognosis in a small group of patients with B‐cell chronic lymphocytic leukemia (B‐CLL), a lymphoproliferative disorder characterized by a heterogeneous clinical course. In the present work, 169 patients suffering from B‐CLL were analyzed for the expression of HLA‐G by flow cytometry in order to verify its prognostic value in a larger cohort. We observed a low expression of this molecule on leukemic B cells and no significant relation to clinical data or progression‐free survival time, indicating that this molecule is not as good immunologic prognostic marker for B‐CLL as suggested.
Using Conversation Analysis in Feminist and Critical Research
Authors: Wilkinson Sue , Kitzinger Celia
Published: February 2008

Conversation analysis – the study of talk‐in‐interaction – is proving a valuable tool for politically engaged inquiry and social critique. This article illustrates the use of conversation analysis in feminist and critical research, drawing on a range of empirical studies. After introducing conversation analysis – its theoretical assumptions, methodological practices and empirical findings – it highlights projects based on two key conversation analytic domains: turn‐taking and turn design, and sequence organization and preference structure. The final section examines the key contributions of conversation analysis to feminist and critical work in the areas of categories and gender; lesbian, gay, bisexual and transgender issues; women's labour; and the politics, ethics and design of the research process.
Exploring arboreal ant community composition and co‐occurrence patterns in plantations of oil palm Elaeis guineensis in Borneo and Peninsular Malaysia
Authors: Pfeiffer Martin , Cheng Tuck Ho , Chong Lay Teh
Published: February 2008

The oil palm, Elaeis guineensis, is a native of West Africa and is now extensively grown in south‐east Asia. In 2005, the crop covered four million ha of Malaysia. We examined the arboreal ant fauna in two oil palm plantations that had been farmed with integrated pest management practices for at least 10 yr. Having cut and examined palm fronds from 595 and 503 palms in Borneo and Peninsular Malaysia respectively, we studied diversity in ant assemblages, analysed composition of ant mosaics by stepwise use of null‐models, and explored the influence of exotic vs native species on community structure. Altogether we sampled 52 species of canopy ants, of which 23 species were shared between Borneo and Peninsular Malaysia. Seventeen species in Borneo and 24 species in Peninsular Malaysia accounted for 95% of all species occurrences (SOCs). Fortysix percent of all SOCs belonged to 12 tramp ant species with pan‐tropical distributions. Forty percent of all SOCs were exotic ants. Six dominant species were found in Borneo, five in the Peninsula. The three most abundant species, Anoplolepis gracilipes, Oecophylla smaragdina and Technomyrmex albipes were dominant in both sites. Three dominants were invasive species that were found on more palms than the native group. Dominant tramp species coexisted with non‐dominants more often and tolerated more species of non‐dominant ants than native dominants. Null model analyses indicated that species were arranged in mosaics at both the Peninsular Malaysia and Borneo sites. Dominant species showed much less co‐occurrence than expected by chance, pointing towards species segregation (even in presence of introduced, invasive species). Similar results were obtained for all species. Non‐dominant ants were either positively associated with their dominants, or co‐occurred randomly in the presence of dominant species. In contrast, ant assemblages on palms without dominants showed species segregation.
Predicting local colonization and extinction dynamics from coarser‐scale surveys
Authors: Moody‐Weis Jennifer , Antonovics Janis , Alexander Helen M. , Pilson Diana
Published: February 2008

The demand for methods to translate information between spatial scales (i.e. size of observational units and the total area of study) has intensified given increased recognition that empirical data collection and practical applications occur at scales ranging from individual organisms to landscapes. For example, there has been considerable interest in “scaling‐down” methods that have been successful at predicting fine‐scale species’ distributions from coarse‐scale distributional maps. Here, we describe the application of scaling‐down methods to the estimation of colonization and extinction rates in metapopulations using long‐term, large‐scale data sets of two roadside plant species,Helianthus annuusandSilene latifolia. Fine‐scale data collected from roadside populations were aggregated to generate data at several increasingly coarse scales. The relationships between occupancy, colonization, or extinction and the scale of measurement (scale‐curves) were determined using the standard “fully‐nested” method and the “stratified random sampling” method. Both methods were successful at predicting not only occupancy, but also the dynamic metapopulation processes of extinction and colonization (R2values, averaged across species and methods, were 88.5, 69.3, and 88.8%, respectively, for occupancy, extinction, and colonization). Scaling‐down generated more accurate predictions inHelianthus(average R2=88.4) compared toSilene(average R2=63.4), and in both species, scaling‐down generated more accurate predictions for occupancy and colonizations compared to extinctions. This is one of the first demonstrations that dynamic processes are scalable, and provides a useful methodology for dealing with the logistical challenges of collecting fine‐scale data over large geographic areas when studying metapopulation processes or range limits.
RangeModel: tools for exploring and assessing geometric constraints on species richness (the mid‐domain effect) along transects
Authors: Colwell Robert K.
Published: February 2008

RangeModel is a computer application that offers animated demonstrations of the mechanism behind the mid‐domain effect. The program also provides analytical tools for the assessment of geometric constraints in empirical datasets for one‐dimensional domains (transects). The mid‐domain effect (MDE) is the increasing overlap of species ranges towards the center of a shared, bounded domain due to geometric boundary constraints in relation to the distribution of range sizes, producing a peak or plateau of species richness towards the center of the domain. Domains may be spatial, temporal, or functional. RangeModel is a stand‐alone, graphical‐interface, freeware application for PC and Mac OS platforms.
k‐symmetric AKS systems and flat immersions into spheres
Authors: Brander David
Published: February 2008

We define a large class of integrable nonlinear PDEs, k‐symmetric AKS systems, with solutions that evolve on finite‐dimensional subalgebras of loop algebras and linearize on an associated algebraic curve. We prove that periodicity of the associated algebraic data implies a type of quasiperiodicity for the solution, and show that the problem of isometrically immersing n dimensional Euclidean space into a sphere of dimension 2n – 1 can be addressed via this scheme, producing infinitely many real analytic solutions.
Stability Increase of Aerodynamically Unstable Rotors Using Intentional Mistuning
Authors: Martel Carlos , Corral Roque , Llorens José Miguel
Published: February 2008

A new simple asymptotic mistuning model, which constitutes an extension of the well known fundamental mistuning model for groups of modes belonging to a modal family exhibiting a large variation of the tuned vibration characteristics, is used to analyze the effect of mistuning on the stability properties of aerodynamically unstable rotors. The model assumes that both the aerodynamics and the structural dynamics of the assembly are linear, and retains the first-order terms of a fully consistent asymptotic expansion of the tuned system where the small parameter is the blade mistuning. The simplicity of the model allows the optimization of the blade mistuning pattern to achieve maximum rotor stability. The results of the application of this technique to realistic welded-in-pair and interlock low-pressure-turbine rotors are also presented.
Investigation of Three-Dimensional Unsteady Flows in a Two-Stage Shrouded Axial Turbine Using Stereoscopic PIV—Kinematics of Shroud Cavity Flow
Authors: Il Yun Yong , Porreca Luca , Kalfas Anestis I. , Jin Song Seung , Abhari Reza S.
Published: February 2008

This paper presents an experimental study of the behavior of leakage flow across shrouded turbine blades. Stereoscopic particle image velocimetry and fast response aerodynamic probe measurements have been conducted in a low-speed two-stage axial turbine with a partial shroud. The dominant flow feature within the exit cavity is the radially outward motion of the main flow into the shroud cavity. The radial migration of the main flow is induced by flow separation at the trailing edge of the shroud due to a sudden area expansion. The radially outward motion is the strongest at midpitch as a result of interactions between vortices formed within the cavity. The main flow entering the exit cavity divides into two streams. One stream moves upstream toward the adjacent seal knife and reenters the main flow stream. The other stream moves downstream due to the interaction with the thin seal leakage flow layer. Closer to the casing wall, the flow interacts with the underturned seal leakage flow and gains swirl. Eventually, axial vorticity is generated due to these complex flow interactions. This vorticity is generated by a vortex tilting mechanism and gives rise to additional secondary flow. Because of these fluid motions combined with a contoured casing wall, three layers (the seal leakage layer, cavity flow layer, and main flow) are formed downstream of the shroud cavity. This result is different from the two-layer structure, which is found downstream of conventional shroud cavities. The seal leakage jet formed through the seal clearance still exists at 25.6% axial chord downstream of the second rotor. This delay of complete dissipation of the seal leakage jet and its mixing with the cavity flow layer is due to the contoured casing wall. Time-averaged flow downstream of the shroud cavity shows the upstream stator’s influence on the cavity flow. The time-averaged main flow can be viewed as a wake flow induced by the upstream stator whose separation at the shroud trailing edge induces pitchwise non-uniformity of the cavity flow.
Combustion Instability and Emission Control by Pulsating Fuel Injection
Authors: Paschereit Christian Oliver , Gutmark Ephraim
Published: February 2008

Open-loop control methodologies were used to suppress symmetric and helical thermoacoustic instabilities in an experimental low-emission swirl-stabilized gas-turbine combustor. The controllers were based on fuel (or equivalence ratio) modulations in the main premixed combustion (premixed fuel injection (PMI)) or, alternatively, in the secondary pilot fuel. PMI included symmetric and asymmetric fuel injection. The symmetric instability mode responded to symmetric excitation only when the two frequencies matched. The helical fuel injection affected the symmetric mode only at frequencies that were much higher than that of the instability mode. The asymmetric excitation required more power to obtain the same amount of reduction as that required by symmetric excitation. Unlike the symmetric excitation, which destabilized the combustion when the modulation amplitude was excessive, the asymmetric excitation yielded additional suppression as the modulation level increased. The NOx emissions were reduced to a greater extent by the asymmetric modulation. The second part of the investigation dealt with the control of low frequency symmetric instability and high frequency helical instability by the secondary fuel injection in a pilot flame. Adding a continuous flow of fuel into the pilot flame controlled both instabilities. However, modulating the fuel injection significantly decreased the amount of necessary fuel. The reduced secondary fuel resulted in a reduced heat generation by the pilot diffusion flame and therefore yielded lower NOx emissions. The secondary fuel pulsation frequency was chosen to match the time scales typical to the central flow recirculation zone, which stabilizes the flame in the burner. Suppression of the symmetric mode pressure oscillations by up to 20dB was recorded. High frequency instabilities were suppressed by 38dB, and CO emissions reduced by using low frequency modulations with 10% duty cycle.
Generalized Eigenvalue Decomposition in Time Domain Modal Parameter Identification
Authors: Zhou Wenliang , Chelidze David
Published: February 2008

This paper is intended to point out the relationship among current time domain modal analysis methods by employing generalized eigenvalue decomposition. Ibrahim time domain (ITD), least-squares complex exponential (LSCE) and eigensystem realization algorithm (ERA) methods are reviewed and chosen to do the comparison. Reformulation to their original forms shows these three methods can all be attributed to a generalized eigenvalue problem with different matrix pairs. With this general format, we can see that single-input multioutput (SIMO) methods can easily be extended to multi-input multioutput (MIMO) cases by taking advantage of a generalized Hankel matrix or a generalized Toeplitz matrix.
Finite Element Model for Hysteretic Friction Damping of Traveling Wave Vibration in Axisymmetric Structures
Authors: Tangpong X. W. , Wickert J. A. , Akay A.
Published: February 2008

A finite element method is developed to treat the steady-state vibration of two axisymmetric structures—a base substructure and an attached damper substructure—that are driven by traveling wave excitation and that couple through a spatially distributed hysteretic friction interface. The base substructure is representative of a rotating brake rotor or gear, and the damper is a ring affixed to the base under preload and intended to control vibration through friction along the interface. In the axisymmetric approximation, the equation of motion of each substructure is reduced in order to the number of nodal degrees of freedom through the use of a propagation constant phase shift. Despite nonlinearity and with contact occurring at an arbitrarily large number of nodal points, the response during sticking, or during a combination of sticking and slipping motions, can be determined from a low-order set of computationally tractable nonlinear algebraic equations. The method is applicable to element types for longitudinal and bending vibration, and to an arbitrary number of nodal degrees of freedom in each substructure. In two examples, friction damping of the coupled base and damper is examined in the context of in-plane circumferential vibration (in which case the system is modeled as two unwrapped rods), and of out-of-plane vibration (alternatively, two unwrapped beams). The damper performs most effectively when its natural frequency is well below the base’s natural frequency (in the absence of contact), and also when its natural frequency is well separated from the excitation frequency.
Optimization of Boundary Supports for Sound Radiation Reduction of Vibrating Structures
Authors: Denli H. , Sun J. Q.
Published: February 2008

The purpose of this research is to design optimal boundary supports for minimum structural sound radiation. The influence of the boundary conditions on the structural dynamics of a cantilever beam is first examined to motivate the research. The boundary supports constraining both the in- and out-of-plane degrees of freedom of the plate are considered as the design parameters. The fixed and free boundary degrees of freedom are represented by a continuous function with the help of homogenization. Analytical expressions of sensitivity functions are employed in the optimization, leading to more efficient and accurate numerical solutions. The sensitivity expressions are based on the linear equation system obtained with the finite element method. Numerical examples of single frequency and broadband optimizations are presented. The sensitivity of the optimal design parameters with respect to small random perturbations is also studied. The examples demonstrate that an encouraging reduction of sound radiation as measured by the mean square normal velocity can be achieved with the optimal boundary conditions as compared with the base line structure.
Numerical Investigation of Thermofluid Flow Characteristics With Phase Change Against High Heat Flux in Porous Media
Authors: Yuki Kazuhisa , Abei Jun , Hashizume Hidetoshi , Toda Saburo
Published: February 2008

This study numerically evaluates thermofluid flow characteristics in porous medium by a newly developed “modified two-phase mixture model” applying Ergun’s law and a two-energy model instead of a one-energy model. In a single-phase flow case, thermal nonequilibrium between a solid phase and a fluid phase is observed in the area where imposed heat conducts from a heating wall and further convective heat transfer is more active. The degree of thermal nonequilibrium has a positive correlation with the increase in flow velocity and heat flux input. In the case of two-phase flow, the thermal nonequilibrium is remarkable in the two-phase region because the solid-phase temperature in this region is far beyond saturation temperature. A difference between these two models is obvious especially in the two-phase flow case, so that the numerical simulation with the modified two-phase mixture model is indispensable under the high heat flux conditions of over 1MW∕m2.
Heat Transfer in the Flow of a Cold, Axisymmetric Vertical Liquid Jet Against a Hot, Horizontal Plate
Authors: Shu Jian-Jun , Wilks Graham
Published: February 2008

The paper considers heat transfer characteristics of thin film flow over a hot horizontal flat plate resulting from a cold vertical jet of liquid falling onto the surface. A numerical solution of high accuracy is obtained for large Reynolds numbers using the modified Keller box method. For the flat plate, solutions for axisymmetric jets are obtained. In a parallel approximation theory, an advanced polynomial approximation for the velocity and temperature distribution is employed and results are in good agreement with those obtained using a simple Pohlhausen polynomial and the numerical solutions.
Numerical Analysis of Wooden Porous Media Effects on Heat Transfer From a Staggered Tube Bundle
Authors: Layeghi Mohammad
Published: February 2008

A numerical analysis of forced convective heat transfer from a staggered tube bundle with various low conductivity wooden porous media inserts at maximum Reynolds numbers 100 and 300, Prandtl number 0.7, and Darcy number 0.25 is presented. The tubes are at constant temperature. The extended Darcy–Brinkman–Forchheimer equations and corresponding energy equation are solved numerically using finite volume approach. Parametric studies are done for the analysis of porous medium thermal conductivity and Reynolds number on the local Nusselt number distribution. Three different porous media with various solid to fluid thermal conductivity ratios 2.5, 5, and 7.5 are used in the numerical analysis. The results are compared with the numerical data for tube bundles without porous media insert and show that the presence of wooden porous media can increase the heat transfer from a tube bundle significantly (more than 50% in some cases). It is shown that high conductivity porous media are more effective than the others for the heat transfer enhancement from a staggered tube bundle. However, the presence of a porous medium increases the pressure drop. Therefore, careful attention is needed for the selection of a porous material with good heat transfer characteristics and acceptable pressure drop.
Mode Pursuing Sampling Method for Discrete Variable Optimization on Expensive Black-Box Functions
Authors: Sharif Behnam , Wang G. Gary , ElMekkawy Tarek Y.
Published: February 2008

Based on previously developed Mode Pursuing Sampling (MPS) approach for continuous variables, a variation of MPS for discrete variable global optimization problems on expensive black-box functions is developed in this paper. The proposed method, namely, the discrete variable MPS (D-MPS) method, differs from its continuous variable version not only on sampling in a discrete space, but moreover, on a novel double-sphere strategy. The double-sphere strategy features two hyperspheres whose radii are dynamically enlarged or shrunk in control of, respectively, the degree of “exploration” and “exploitation” in the search of the optimum. Through testing and application to design problems, the proposed D-MPS method demonstrates excellent efficiency and accuracy as compared to the best results in literature on the test problems. The proposed method is believed a promising global optimization strategy for expensive black-box functions with discrete variables. The double-sphere strategy provides an original search control mechanism and has potential to be used in other search algorithms.
A Design-Driven Validation Approach Using Bayesian Prediction Models
Authors: Chen Wei , Xiong Ying , Tsui Kwok-Leung , Wang Shuchun
Published: February 2008

In most of the existing work, model validation is viewed as verifying the model accuracy, measured by the agreement between computational and experimental results. Due to the lack of resource, accuracy can only be assessed at very limited test points. However, from the design perspective, a good model should be considered the one that can provide the discrimination (with good resolution) between competing design candidates under uncertainty. In this work, a design-driven validation approach is presented. By combining data from both physical experiments and the computer model, a Bayesian approach is employed to develop a prediction model as the replacement of the original computer model for the purpose of design. Based on the uncertainty quantification with the Bayesian prediction and, subsequently, that of a design objective, some decision validation metrics are further developed to assess the confidence of using the Bayesian prediction model in making a specific design choice. We demonstrate that the Bayesian approach provides a flexible framework for drawing inferences for predictions in the intended, but maybe untested, design domain. The applicability of the proposed decision validation metrics is examined for designs with either a discrete or continuous set of design alternatives. The approach is demonstrated through an illustrative example of a robust engine piston design.
Synthesizing Single DOF Linkages Via Transition Linkage Identification
Authors: Murray Andrew P. , Turner Michael L. , Martin David T.
Published: February 2008

A linkage is partially classified by identifying those links capable of unceasing and drivable rotation and those that are not. In this paper, we examine several planar single degree-of-freedom linkages to identify all changes to the physical parameters that may alter this classification. The limits on the physical parameters that result in no change in the classification are defined by transition linkages. More rigorously, a transition linkage possesses a configuration at which the matrix defined by the derivative of the loop closure equations with respect to the joint variables loses rank. Transition linkages divide the set of all linkages into different classifications. In the simplest cases studied, transition linkage identification produces a comprehensive classification scheme. In all cases, this identification is used to alter a linkage’s physical parameters without changing its classification and produces insight into the selection of these parameters to produce a desired classification.
Design Optimization With System-Level Reliability Constraints
Authors: McDonald M. , Mahadevan S.
Published: February 2008

Reliability-based design optimization (RBDO) of mechanical systems is computationally intensive due to the presence of two types of iterative procedures—design optimization and reliability estimation. Single-loop RBDO algorithms offer tremendous savings in computational effort, but they have so far only been able to consider individual component reliability constraints. This paper presents a single-loop RBDO formulation and an equivalent formulation that can also include system-level reliability constraints. The formulations allow the allocation of optimal reliability levels to individual component limit states in order to satisfy both system-level and component-level reliability requirements. Four solution algorithms to implement the second, more efficient formulation are developed. A key feature of these algorithms is to remove the most probable points from the decision space, thus avoiding the need to calculate Hessians or gradients of limit state gradients. It is shown that with the proposed methods, system-level RBDO can be accomplished with computational expense equivalent to several cycles of computationally inexpensive single-loop RBDO based on second-moment methods. Examples of this new approach applied to series, parallel, and combined systems are provided.
Dexterous Manipulation of Origami Cartons With Robotic Fingers Based on the Interactive Configuration Space
Authors: Yao Wei , Dai Jian S.
Published: February 2008

This paper investigates the equivalent mechanism structure of origami cartons and for the first time proposes a quantitative model of cartons and the interactive configuration space for folding origami cartons. With an analysis of the equivalent mechanism, gusset vertexes of cartons are investigated based on their equivalent spherical linkages and identified as guiding linkages that determine folding. Having established a kinematics model, a configuration control vector is characterized to control carton manipulation. The information of this configuration control vector is passed to the tip of a robotic finger, and the finger configuration space is hence identified. The paper further introduces configuration transformation and creates a carton interactive configuration space, leading to generating trajectories of all four configuration control vectors and, subsequently, to finger operation trajectories. This results in making use of four robotic fingers for folding origami cartons. The interactive technique is further used for final tucking carton flaps. A novel rig with robotic fingers is then presented to demonstrate the principle and concept.
Disturbed Configuration Bifurcation Characteristics of Gough–Stewart Parallel Manipulators at Singular Points
Authors: Wang Yu-Xin , Li Yu-Tong
Published: February 2008

In this paper, the disturbed configuration bifurcation characteristics of Gough–Stewart parallel manipulators at singular points are investigated. At first, the expended equation corresponding with the kinematics equation of the manipulator is introduced for eliminating the rank reduction and obtaining all of the theoretical singular points. Then, the assembly configurations at the singular points and the configuration bifurcation characteristics near them have been studied. It is found that the configuration bifurcation characteristics at the singular points belong to the turning point type through the Golubitsky–Schaeffer normal form identification. Next, utilizing the universal unfolding approach, the configuration bifurcation characteristics under the perturbation parameters applied to the extendable legs are analyzed. The investigation reveals that all configuration branches converged in the same singular point in the unperturbed system will be separated in the disturbed system. Based on this discovery, a novel approach for the parallel manipulator to pass through the singular points with a desired configuration is presented. The method presented in this paper can be utilized as the singularity avoidance approach for the parallel manipulators with strict trace and exact orientation control requirements, such as virtual parallel machine tools.
Stiffness Characteristics of Carton Folds for
Packaging
Authors: Dai Jian S. , Cannella Ferdinando
Published: February 2008

Recent studies for packaging using cartons have modeled carton folds as equivalent mechanisms by considering creases as revolute joints and panels as links. This raises the interest in the study of stiffness characteristics of creases, which have a variable stiffness in contrast to a constant stiffness of a revolute joint and subsequently that of a whole carton fold. This paper investigates the stiffness characteristics of creases and reveals for the first time the folding motion and moment diagram in carton manipulation. Three characteristic stages were provided to characterize the crease stiffness, which has a variable value during carton manipulation. The paper further investigates the integrated stiffness of a combination joint and develops the integrated stiffness of a complete carton fold. The study is then extended to the integrated stiffness of a type of carton folds.
Experimental Validation of Input Torque Balancing Applied to Weaving Machinery
Authors: Demeulenaere Bram , Spaepen Pieter , Masselis Stephan , Cornelissen Philip , Pinte Gregory , Hemelsoen Jan , Boonen René , Roelstraete Kristof , Desmet Wim , Swevers Jan , Schutter Joris De
Published: February 2008

This paper considers a class of high-speed airjet weaving machines that is characterized by excessive harness frame vibration, resulting in premature failure. This problem is tackled through addition of an auxiliary, input torque balancing mechanism: A centrifugal pendulum, of which the pendulum motion is imposed by an internal cam. While earlier work by the same authors focused on the design, optimization, and robustness analysis of this mechanism, the current paper presents experimental results. The considered setup is an industrial weaving machine à blanc equipped with a centrifugal pendulum prototype. Below a critical speed, the prototype functions as predicted and significantly improves the machine dynamics: The drive speed fluctuation is reduced by a factor of 2.5 and the vibration level of the harness frames is halved. Above the critical speed, however, torsional resonance dominates the machine dynamics. This phenomenon is verified on simulation by extending the rigid-body setup model, on which the centrifugal pendulum design is based, with a torsional degree of freedom.
Torque-Angle Formulation of Threaded Fastener Tightening
Authors: Nassar Sayed A. , Yang Xianjie
Published: February 2008

In this paper, the evolution equations of the bearing and thread friction coefficients are proposed based on mechanical behavior of the bolted joint assembly. The study shows excellent correlation between the proposed model and the experimental results for the breakaway torque values in both the tightening and loosening directions. Evaluation of the torque-angle control of the tightening process is made, and a modified torque-angle control approach is proposed. The effect of friction coefficients on the error in the clamping force prediction is analyzed.
A Note on the Shear Influence on Belt Drive Mechanics
Authors: Sorge F.
Published: February 2008

Belt drives work often with short center distances and very different wrap arcs so that high adherence characteristics are required at the belt-pulley contact. In addition, the belt flexural stiffness reduces the contact width, but this decrease may be compensated in part by the belt softening due to the shear compliance.