bluuebunny/crossref_metadata_2025 huggingface dataset:
Urotensin II, from fish to human
Authors: Vaudry Hubert , Do Rego Jean‐Claude , Le Mevel Jean‐Claude , Chatenet David , Tostivint Hervé , Fournier Alain , Tonon Marie‐Christine , Pelletier Georges , Michael Conlon J. , Leprince Jérôme
Published: July 2010

The cyclic peptide urotensin II (UII) was originally isolated from the urophysis of teleost fish on the basis of its ability to contract intestinal smooth muscle. The UII peptide has subsequently been isolated from frog brain and, later on, the pre‐proUII cDNA has been characterized in mammals, including humans. A UII paralog called urotensin II‐related peptide (URP) has been identified in the rat brain. The UII and URP genes originate from the same ancestral gene as the somatostatin and cortistatin genes. In the central nervous system (CNS) of tetrapods, UII is expressed primarily in motoneurons of the brainstem and spinal cord. The biological actions of UII and URP are mediated through a G protein–coupled receptor, termed UT, that exhibits high sequence similarity with the somatostatin receptors. The UT gene is widely expressed in the CNS and in peripheral organs. Consistent with the broad distribution of UT, UII and URP exert a large array of behavioral effects and regulate endocrine, cardiovascular, renal, and immune functions.
Evolution of the opioid/ORL‐1 receptor gene family
Authors: McClendon Jazalle , Lecaude Stephanie , Dores Anthony R. , Dores Robert M.
Published: July 2010

In gnathostomes the kappa, mu, delta, ORL‐1 receptor genes constitute the opioid/ORL‐1 receptor gene family. These genes are most likely the result of two (2R) genome duplication events that occurred during the radiation of the chordates.In stilicoanalysis of the genome of the lamprey,Petromyzon marius, revealed the partial sequences of four genes that may be the result of a lineage specific genome duplication event in the lamprey lineage. The sequencing of cDNAs from the lamprey CNS supports the assumption that these putative lamprey opioid‐like receptor genes are expressed by lamprey neurons. Analysis of gnathostome ORL‐1 receptor sequences support the hypothesis that the ORL‐1 gene has undergone a transition from an opioid receptor that could bind several types of opioid ligands to a receptor in mammals that can only be activated by the FGGF form of the orphanin ligand.
Neuropeptide W: a key player in the homeostatic regulation of feeding and energy metabolism?
Authors: Takenoya Fumiko , Kageyama Haruaki , Shiba Kanako , Date Yukari , Nakazato Masamitsu , Shioda Seiji
Published: July 2010

Neuropeptide W (NPW), recently isolated from porcine hypothalamus, has been identified as the endogenous ligand for both NPBWR1 (GPR7) and NPBWR2 (GPR8), which belong to the orphan G protein–coupled receptor family. NPW is thought to play an important role in the regulation of feeding and drinking behavior, and to be related to the stress response. NPW‐containing neurons are localized in several regions of the brain, including the hypothalamus, hippocampus, limbic system, midbrain, and brain stem. Accumulated evidence suggests that hypothalamic neuropeptides, such as neuropeptide Y (NPY), orexin, melanin‐concentrating hormone (MCH), and proopiomelanocortin (POMC), are involved in the regulation of feeding behavior and energy homeostasis via neuronal circuits in the hypothalamus. NPW also forms part of the feeding‐regulating neuronal circuitry in conjunction with other feeding‐regulating peptide‐containing neurons within the hypothalamus. We summarize our current understanding of the distribution of NPW and of the neuronal interactions between NPW and the different feeding‐regulating peptide‐containing neurons. This review also discusses evidence for the dichotomous actions of NPW on energy balance and the potential mechanisms involved.
Reply to Discussion1 ‐ by George Ice, George Brown, John Gravelle, C. Rhett Jackson, Jeff Light, Timothy Link, Douglas Martin, Dale McGreer, and Arne Skaugset2 “Stream Temperature Relationships to Forest Harvest in Western Washington”3
Authors: Pollock Michael M. , Beechie Timothy J.
Published: July 2010

Pollock, Michael M. and Timothy J. Beechie, 2010. Reply to Discussion –“Stream Temperature Relationships to Forest Harvest in Western Washington” by George Ice, George Brown, John Gravelle, C. Rhett Jackson, Jeff Light, Timothy Link, Douglas Martin, Dale McGreer, and Arne Skaugset. Journal of the American Water Resources Association (JAWRA) 46(4): 843‐847. DOI: 10.1111/j.1752‐1688.2010.00456.x
Local origin of two vegetative compatibility groups ofFusarium oxysporumf. sp.vasinfectumin Australia
Authors: Wang Bo , Brubaker Curt L. , Summerell Brett A. , Thrall Peter H. , Burdon Jeremy J.
Published: July 2010

Pathogenicity and genetic diversity ofFusarium oxysporumfrom geographically widespread nativeGossypiumpopulations, including a cotton growing area believed to be the center of origin of VCG 01111 and VCG 01112 ofF. oxysporumf. sp.vasinfectum(Fov) in Australia, was determined using glasshouse bioassays and AFLPs. Five lineages (A–E) were identified among 856 isolates. Of these, 12% were strongly pathogenic on cotton, 10% were weakly pathogenic and designated wildFov, while 78% were nonpathogenic. In contrast to the occurrence of pathogenic isolates in all five lineages in soils associated with wildGossypium, in cotton growing areas only three lineages (A, B, E) occurred and all pathogenic isolates belonged to two subgroups in lineage A. One of these contained VCG 01111 isolates while the other contained VCG 01112 isolates. Sequence analyses of translation elongation factor‐1α, mitochondrial small subunit rDNA, nitrate reductase and phosphate permease confirmed that AustralianFovisolates were more closely related to lineage A isolates of nativeF. oxysporumthan toFovraces 1–8 found overseas. These results strongly support a local evolutionary origin forFovin Australian cotton growing regions.
Exploring the evolutionary ecology of fungal endophytes in agricultural systems: using functional traits to reveal mechanisms in community processes
Authors: Saunders Megan , Glenn Anthony E. , Kohn Linda M.
Published: July 2010

All plants, including crop species, harbor a community of fungal endophyte species, yet we know little about the biotic factors that are important in endophyte community assembly. We suggest that the most direct route to understanding the mechanisms underlying community assembly is through the study of functional trait variation in the host and its fungal consortium. We review studies on crop endophytes that investigate plant and fungal traits likely to be important in endophyte community processes. We focus on approaches that could speed detection of general trends in endophyte community assembly: (i) use of the ‘assembly rules’ concept to identify specific mechanisms that influence endophyte community dynamics, (ii) measurement of functional trait variation in plants and fungi to better understand endophyte community processes and plant–fungal interactions, and (iii) investigation of microbe–microbe interactions, and fungal traits that mediate them. This approach is well suited for research in agricultural systems, where pair‐wise host–fungus interactions and mechanisms of fungal–fungal competition have frequently been described. Areas for consideration include the possibility that human manipulation of crop phenotype and deployment of fungal biocontrol species can significantly influence endophyte community assembly. Evaluation of endophyte assembly rules may help to fine‐tune crop management strategies.
Richness‐environment relationships in epigaeic ants across the Subantarctic‐Patagonian transition zone
Authors: FERGNANI PAULA NILDA , SACKMANN PAULA , RUGGIERO ADRIANA
Published: July 2010

Abstract. 1. We analysed ant species richness‐environment relationships across the Subantartic‐Patagonian transition, in southern South America. We tested the predictions of the (i) thermal limitation hypothesis: temperature limits ant species richness, (ii) the productivity hypothesis: ant richness is driven by the indirect effect of climate (temperature and precipitation) mediated by changes in plant environment (plant cover and litter accumulation). We also evaluated the effects of (iii) plant species richness, and (iv) habitat use by cattle on richness.

2. We collected ants using 450 pitfall traps within a ∼150 × 150 km area. We used path analysis to evaluate the associations of ant richness with environmental predictors. We evaluated the influence of local abundance variation on richness‐environment relationships; we applied principal co‐ordinates of neighbour matrices to model the spatial autocorrelation in the data and combined spatial and ecological descriptors of ant richness into partial regression.

3. Ant richness responded positively to indirect effects of precipitation mediated by shrub cover and tree cover, towards the west, and by litter accumulation, towards the east of the transition. Direct climatic effects on richness were negative or weak throughout. The local increase in plant species richness and habitat disturbance by cattle promoted an increase in ant richness, mostly towards the east of the transition. These results were not seriously affected by variation in local abundance and the spatial autocorrelation in the data.

4. We suggest that climate, either directly or indirectly, through its biological effect on plant environment interacts with micro‐spatial variation in habitat heterogeneity and disturbance to account for ant species diversity across this transition.
Association of complement factor H Y402H polymorphism and age‐related macular degeneration in Brazilian patients
Authors: Teixeira Anderson G. , Silva Aldacilene S. , Lin Fabio L.H. , Velletri Roberta , Bavia Lorena , Belfort Jr Rubens , Isaac Lourdes
Published: July 2010

Purpose:  The aim of this study was investigate the association between complement Factor H polymorphism (Y402H) and age‐related macular degeneration (AMD) in Brazilian patients.

Methods:  Patients with AMD aged 50 or more and age‐matched healthy controls were enrolled in the study. Genomic DNA was isolated from leucocytes of patients and controls; the Y402H polymorphism of complement Factor H gene (CFH) was determined by polymerase chain reaction directed sequencing.

Results:  The frequency of 1277C allele of Factor H was 56.30% in patients with AMD compared with 36.51% in controls (p‐value = 0.001). The genotypic distribution differed significantly between the two groups (1277CC 36.98%, 1277CT 38.65% and 1277TT 24.37% for AMD group; 1277CC 13.16%, 1277CT 46.71% and 1277TT 40.13% for controls, p‐value = 0.001). The odds ratio for patients with AMD carrying only one 1277C allele was 1.36 and for those carrying two 1277C alleles was 4.63, when compared to the control group.

Conclusions:  These results suggest the Y402H polymorphism of CFH is a risk factor to the development of AMD in Brazilian patients. This is in accordance with findings from the majority of previous study population in Europe and North American.
Nutraceuticals and Atherosclerosis: Human Trials
Authors: Badimon Lina , Vilahur Gemma , Padro Teresa
Published: July 2010

The high prevalence of obesity, atherosclerosis, and cardiovascular disease (CVD) is largely attributable to the contemporary lifestyle that is often sedentary and includes a diet high in saturated fats and sugars and low ingestion polyunsaturated fatty acids (PUFAs), fruit, vegetables, and fiber. Epidemiological studies have confirmed a strong association between fat intake, especially saturated‐ and transfatty acids, plasma cholesterol levels, and rate of coronary heart disease (CHD) mortality. In counterpart, beneficial cardiovascular effects have been reported in populations consuming the “healthy” Mediterranean‐type diet. Indeed, many nutrients and phytochemicals in fruits, vegetables, and wine, including fiber, vitamins, minerals, antioxidants, have shown to be independently or jointly responsible for the apparent reduction in CVD risk. Therefore, in patients with overt CVD, efforts have focused on combining both drug treatments and nutrition interventions. Undoubtedly, the advances in the knowledge of both the disease processes and healthy dietary components have provided new avenues to develop pharmaceutical and/or dietary strategies to halt the development of vascular disease. In this regard, within the last years, pioneering nutritional strategies, such as nutraceuticals, have been developed aimed at reducing the main atherosclerotic risk factors and promoting cardiovascular health. Furthermore, a growing body of clinical evidence has demonstrated positive cardiovascular effects associated with dietary fibers, cholesterol‐lowering natural agents, olive oil, ω‐3 PUFAs, antioxidants, and polyphenols intake. Moreover, monounsaturated fatty acids intake has shown to modulate the expression of key atherosclerotic‐related genes. Yet, in the case of antioxidants, some large clinical trials have failed to confirm such atheroprotective effects. Furthermore, there might be interactions between these natural food supplements and cardiovascular medications that cannot be overlooked. Hence, there is a need for a better understanding and more scientific evidence of the relative contribution of major nutraceutical constituents to the inhibition of the progression of atherosclerosis and its clinical consequences.
Safety of Herbal Supplements: A Guide for Cardiologists
Authors: Cohen Pieter A. , Ernst E.
Published: July 2010

Many patients use herbal supplements to treat chronic cardiovascular conditions and often combine herbal ingredients with cardiovascular medications. However, physicians do not reliably elicit a history of herbal use from their patients and may overlook herbal supplements' adverse effects. Although often considered harmless by patients, herbal supplements may cause adverse cardiovascular effects from an herbal ingredient, a contaminant, or an herb–drug interaction. Herbal stimulants, including bitter orange, ephedra, caffeine, guarana, maté, kola, areca, lobelia, khat, and others are the most common category of herbal therapies to cause cardiovascular effects. However, dozens of other herbal ingredients have also been linked to adverse cardiovascular events. In addition to listed ingredients, herbal supplements may become contaminated at a number of stages during production. Pesticides, heavy metals, bacteria, and pharmaceutical agents have been detected in herbal supplements. Supposedly “herbal” products that are adulterated with prescription anorectics, antidepressants, diuretics, phosphodiesterase‐5 inhibitors along with other medications have been identified throughout Europe, North America, and Asia. All of these adulterants have potential cardiovascular effects. Herbal interactions with a variety of cardiovascular medications may also lead to adverse events. Herbal ingredients may cause pharmacokinetic as well as pharmacodynamic herb–drug interactions. We review clinically relevant patterns of adverse cardiovascular reactions to herbal supplements, and we provide resources and recommendations for practicing cardiologists evaluating patients with suspected herbal adverse effects.
Cardiovascular Ion Channels as a Molecular Target of Flavonoids
Authors: Scholz Eberhard P. , Zitron Edgar , Katus Hugo A. , Karle Christoph A.
Published: July 2010

Flavonoids are a class of naturally occurring polyphenols abundant in edibles and beverages of plant origin. Epidemiological studies consistently associate high flavonoid intake with a reduced risk for the development of cardiovascular diseases. So far these beneficial effects have been mainly attributed to nonspecific antioxidant and antiinflammatory properties. However, there is an increasing body of evidence that flavonoids specifically target molecular structures including cardiovascular ion channels. Playing a pivotal role in the regulation of vascular tone and cardiac electric activity, ion channels represent a major target for the induction of antihypertensive and cardioprotective effects. Thus, pharmacological properties of flavonoids on cardiovascular ion channels, ion currents and tissue preparations are being increasingly addressed in experimental studies. Whereas it has become clear that cardiovascular ion channels represent an important molecular target of flavonoids, the published data have not yet been systematically reviewed.
Scaphochlamys krauensis and S. pusilla spp. nov. (Zingiberaceae) from Krau Wildlife Reserve, Pahang, Peninsular Malaysia
Authors: Sam Y. Y. , Ibrahim H. , Saw L. G.
Published: July 2010

Two new species of Scaphochlamys, S. krauensis Y. Y. Sam and S. pusilla Y. Y. Sam, from the Krau Wildlife Reserve, Pahang are described and illustrated. Another two Scaphochlamys species, S. pennipicta and S. oculata are also reported from Krau Wildlife Reserve, considerably extending their known distribution. An identification key for all four Scaphochlamys species found in the Krau Wildlife Reserve is provided.
The elliptic Hall algebra, Cherednik Hecke algebras and Macdonald polynomials
Authors: Schiffmann O. , Vasserot E.
Published: July 2010

We exhibit a strong link between the Hall algebraHXof an elliptic curveXdefined over a finite field 𝔽l(or, more precisely, its spherical subalgebraU+X) and Cherednik’s double affine Hecke algebras$\ddot {\mathbf {H}}_n$of type GLn, for alln. This allows us to obtain a geometric construction of the Macdonald polynomialsPλ(q,t−1) in terms of certain functions (Eisenstein series) on the moduli space of semistable vector bundles on the elliptic curveX.
Evaluating End-of-Life Recovery Profit by a Simultaneous Consideration of Product Design and Recovery Network Design
Authors: Kwak Minjung , Kim Harrison M.
Published: July 2010

Product recovery has become a field of rapidly growing interest for product manufacturers as a promising solution for product stewardship as well as for economic viability. Because product recovery is highly dependent on the way a product is designed, it should be considered in the design stage so that the product is designed to have high recovery potential. To make a product easy to recover, manufacturers first need to understand the links between product design and recovery profit and be able to evaluate which design is better than others and why. This study proposes a framework for analyzing how design differences affect product recovery and what architectural characteristics are desirable from the end-of-life perspective. For better design evaluation, an optimization-based model is developed, which considers product design and recovery network design simultaneously. For illustration, a comparative study with cell phone examples is presented. Three cell phone handset designs that share the same design concept but have different architectural characteristics are created, and the recovery potential of each design variant is evaluated under three different recovery scenarios. The results show that the framework can highlight preferred design alternatives and their design implications for the economic viability of end-of-life recovery.
Enumeration of Feasible Clutching Sequences of Epicyclic Gear Mechanisms
Authors: Hassan Shaker S.
Published: July 2010

A new methodology for enumeration of feasible clutching sequences of epicyclic gear mechanism (EGM) composed of two or more fundamental gear entities is presented. The method relies on previous work on algorithmic technique. It improves on existing techniques used for automatic transmission mechanisms in its ability to accurately solve the kinematics of geared mechanisms and estimating their velocity ratios and arranging them in a descending order in a simpler manner without depending on certain gear sizes. Twelve velocity-ratio-relations are derived for any four coaxial links of an epicyclic gear train. These velocity-ratio-relations are three more than the nine relations given in literature. In addition, the velocity ratios can be arranged in a descending sequence without using complicated artificial intelligence technique or complicated computer algorithm. The present methodology is judged to be more efficient for enumeration of all feasible clutching sequences of an EGM.
An Ease-Off Based Method for Loaded Tooth Contact Analysis of Hypoid Gears Having Local and Global Surface Deviations
Authors: Kolivand M. , Kahraman A.
Published: July 2010

Actual hypoid gear tooth surfaces do deviate from the theoretical ones either globally due to manufacturing errors or locally due to reasons such as tooth surface wear. A practical methodology based on ease-off topography is proposed here for loaded tooth contact analysis of hypoid gears having both local and global deviations. This methodology defines the theoretical pinion and gear tooth surfaces from the machine settings and cutter parameters, and constructs the surfaces of the theoretical ease-off and roll angle to compute for the unloaded contact analysis. This theoretical ease-off topography is modified based on tooth surface deviations and is used to perform a loaded tooth contact analysis according to a semi-analytical method proposed earlier. At the end, two examples, a face-milled hypoid gear set having local deviations and a face-hobbed one having global deviations, are analyzed to demonstrate the effectiveness of the proposed methodology in quantifying the effect of such deviations on the load distribution and the loaded motion transmission error.
Reliability Sensitivity Analysis for Rack-and-Pinion Steering Linkages
Authors: Huang Xianzhen , Zhang Yimin
Published: July 2010

In this paper, a reliability sensitivity analysis methodology for the kinematic accuracy of rack-and-pinion steering linkages (RPSLs) is developed. The direct linearization method is applied to obtain the kinematic accuracy errors of planar linkages due to link-length variations. The RPSL widely used in many types of vehicles is chosen as an example to propose an analytical model for reliability analysis of the kinematic accuracy of planar linkages. Furthermore, reliability sensitivity analysis of planar linkages, which is the main focus of this paper, is used to compute the reliability sensitivity of the kinematic accuracy of steering linkages with respect to the statistical parameters (e.g., mean, standard deviation, or higher moments) of the basic errors of random variables. Finally, the practicality and efficiency of the proposed method are demonstrated by a numerical example.
Analyzing Field Failures of Engine Valve Springs in Presence of Non Metallic Inclusions by Applying Statistical and Fracture Mechanics Models
Authors: Choucair Hassan , Jawad Badih
Published: July 2010

An Engine valve spring, which is made of high strength, clean steel, is a very important component in an engine for controlling the movement of exhaust and the intake valve. It is designed to survive an infinite life under high cyclic stress. Hence, the reliability of engine valve spring is a very important issue from the warranty point of view. The relationship between the stresses applied on the valve spring during operation of an engine and the number of cycles (S-N) curve, is strongly influenced by the presence of inclusions which are microscopic particles of extraneous material within the metal matrix. This implies that the fatigue strength of the material will experience a drop and shift in the endurance and consequently a decrease in the Reliability level of the valve spring. Field and experimental data of engine valve springs failed due to inclusions will be utilized for predicting the fatigue strength of valve spring material by applying extreme value statistics and fracture mechanics models.
The Machining of the Spherical Gear With Concave Cone Teeth and Its Cutting Tool
Authors: Huran Liu
Published: July 2010

The spherical gear, or globular gear is a ball, on the ball there are a series of holes. The spherical gear is the key component of the robot’s wrist. As shown in fig.1, by using the spherical crowns of two different spherical centers as a joint curve surface, and their spherical center as a rotational center, the spherical gearing can be formed on two spherical surfaces with convex teeth and concave teeth engaging each other. The robot’s wrist differs from the wrist of human kind in that, it can transmit rotational movement from the upper arm to the lower arm continuously, while the angle between the upper arm and the lower arm is changing. In the formal papers, the protruding teeth have the shape of a cone, while the concave teeth are the conjugate surface of them. The protruding teeth with straight surface are of cause easy to be machined. But the concave teeth are very hard to be machined. The special machining method such as the electric spark machining has to be employed to deal with this kind of work. Theoretical analysis show [1] that the concave tooth profile of spherical gear can be rotate involutes surface. The curved surface of convex tooth profiles are formed according to concave tooth profiles through the envelopes of dual parameters. It is approximately a rotate involutes surface. The processing technique of convex and concave tooth profiles is quite complex. Reference [2] gives a new tooth profile. That is, to use cone instead of convex tooth profile with a rotate involutes surface. The rough manufacturing and grinding of convex tooth cylinder can thus become much easy. But the manufacturing of concave tooth surface remains complex. This paper proposes that concave teeth profiles take the place of cone. In that case we can use cone milling. In order to underline the originality of my work, I should say: In the former approach the convex teeth are the cones, while the profile of the concave teeth are the conjugate tooth surfaces of the cone. In my approach the concave teeth are the cones, while the profile of the convex teeth are the conjugate tooth surfaces of the cone. Just small change, the machining properties improved dramatically.
The Effects of Perfluoroalkyl Carboxylic Acid Coating of Al Particles to Flame Propagation
Authors: Dikici B. , Pantoya M. L. , Jouet R. J.
Published: July 2010

In this study, two types of nano-Al/metal oxide composites are examined. The first Al sample is passivated with Al2O3 and treated with perfluoroalkyl carboxylic acid (C13F27COOH). The second Al sample is devoid of an alumina shell and instead passivated with perfluoroalkyl carboxylic acid (C13F27COOH). The goal of this study is to understand the role of the passivation shell and associated reaction mechanism on flame propagation. Results show that when there is no alumina passivation shell encasing the Al core the flame propagation rates are reduced by two orders of magnitude. All flame propagation experiments were performed in a confined flame tube apparatus which may not be ideal for characterizing materials with significantly different ignition sensitivities. Results indicate that flame speeds measured with this apparatus are dependent on the ignition sensitivity of the mixture. Acid treated Al particles are shown to be roughly five times less ignition sensitive than the Al particles with no acid treatment; however, both particles produce roughly the same heat of combustion in thermal equilibrium measurements.
A Bi-Directional Ultrasonic Elliptical Vibration Actuator (BUEVA) for Micro Machining
Authors: Ammouri Ali H. , Hamade Ramsey F.
Published: July 2010

Presented is the detailed design and implementation of a bi-directional ultrasonic elliptical vibration actuator (BUEVA) for micro machining. Removal of material occurs via a generated elliptical tool motion resembling a natural ‘spoon feeding’ action in contrast to in-plane, horizontal motion utilized by most existing setups. The motion is generated by two stacked ceramic multilayer actuator ring (SCMAR) piezo elements vibrating out of phase in the tool’s axial and transverse directions. The amplitude of vibration of the tool is controlled in order to vary the cutting depth according to the desired cutting parameters. To ensure precise tool positioning, the BUEVA actuator is fitted to a 3-axis precision machining center that provides the necessary tool path. The cutting forces and the resulting surface finish are both numerically modeled and then experimentally measured by a 3-axis mini dynamometer and a surface profilometer, respectively. Preliminary cutting results show good dimensional definition and surface integrity.
Effects of Nozzle Hole Arrangement on Diesel Engine Emissions
Authors: Karra Prashanth K. , Kong Song-Charng
Published: July 2010

Various diesel injectors and injection pressures were tested along with exhaust gas recirculation to achieve low NOx and soot emissions. The injectors used in the study included a 6-hole nozzle, a 10-hole nozzle, and a 6-hole convergent nozzle with a K-factor of 3. All three injectors had the same flow numbers and they were effective in reducing NOx and soot emissions at appropriate conditions. It was found that low temperature combustion can be achieved by using high levels of exhaust gas recirculation with late injection timings. High injection pressures significantly reduced soot emissions at conventional injection timings. The effect of injection pressure was not significant at retarded injection timings, i.e., 5 ATDC. The convergent nozzle was found to produce higher soot emissions and its effects on NOx emissions and fuel consumption were not significant. The small nozzle size in the 10-hole injector can generate smaller fuel drops and lead to better atomization. The 10-hole injector appeared to have better air utilization and resulted in significant reductions in NOx and soot emissions over a wide range of operating conditions.
Structural Design of a Silicon Six-Wafer Micro-Combustor Under the Effect of Hydrogen/Air Ratio
Authors: Zhu Lin , Jen Tien-Chien , Yin Chen-Long , Zhu Mei , Yen Yi-Hsin , Zhang Jianhua
Published: July 2010

This paper studied the structural design issues associated with a silicon six–wafer micro-combustor under the effect of hydrogen/air ratio. The objective of this study is to establish a methodology for designing highly stressed micro-fabricated structures. Due to the facts that there are differences in sizes between a micro-combustor and a conventional combustor, the fracture strength of silicon in room temperature is extremely sensitive to its surface processing methods. It is worth noting that the silicon has relatively poor high temperature strength and creep resistance when the temperature is above the brittle to ductile transition temperature (BDTT), e.g. 900K [1]. Some experimental and numerical simulation results [1,2] have shown that the flame front in the micro-combustor propagates in the upstream of the mixture flow, burns in the recirculation jacket, where the flame temperature could reach 1700∼1800K, and then travels to the outer wall 1000 ∼ 1200K when the equivalence ratio of hydrogen/air is increased to a certain value. This will shorten the fatigue life of the micro-combustor. In order to explore the structural design of the micro-combustor under the effect of different mixture equivalence ratio, combustion characteristics of the combustor were first analyzed using 2D computational Fluid Dynamics (CFD) simulation when the mixture flow rate was constant, and then the 3D Finite Element Method based on Finite Element Software COSMOS\works was employed for thermo-mechanical analysis. The results show that the critical failure occurs around the burning area in the recirculation jacket, which is in agreement with the experimental results in the published literature. The results of this study can be used for the design and improvement of the micro-combustors.
Numerical Predictions of Hydrogen-Air Rectangular Channel Flows Augmented by Catalytic Surface Reactions
Authors: Amano Ryoichi S. , Abou-Ellail Mohsen M. , Kaseb S.
Published: July 2010

Catalytic combustion of hydrogen-air boundary layers involves the adsorption of hydrogen and oxygen into a platinum coated surface, chemical reactions of the adsorbed species and the desorption of the resulting products. Readsorption of some produced gases is also possible. The catalytic reactions can be beneficial in porous burners and catalytic reactors that use low equivalence ratios. In this case the porous burner flame can be stabilized at low temperatures to prevent any substantial gas emissions, such as nitrogen oxides. The present paper is concerned with the numerical computations of momentum transfer, heat transfer and chemical reactions in rectangular channel flows of hydrogen-air mixtures. Chemical reactions are included in the gas phase as well as on the solid platinum surfaces. In the gas phase, eight species are involved in 26 elementary reactions. On the platinum hot surfaces, additional surface species are included that are involved in 16 additional surface chemical reactions. The platinum surface temperature distribution is pre-specified, while the properties of the reacting flow are computed. The flow configuration investigated in the present paper is that of a rectangular channel burner. Finite-volume equations are obtained by formal integration over control volumes surrounding each grid node. Hybrid differencing is used to ensure that the finite-difference coefficients are always positive or equal to zero to reflect the real effect of neighboring nodes on a typical central node. The finite-volume equations of the reacting gas flow properties are solved by a combined iterative-marching algorithm. On the platinum surfaces, surface species balance equations, under steady-state conditions, are solved numerically. A non-uniform computational grid is used, concentrating most of the nodes in the boundary sub-layer adjoining the catalytic surfaces. The channel flow computational results are compared with recent detailed experimental data for similar geometry. In this case, the catalytic surface temperature profile along the x-axis was measured accurately and is used in the present work as the boundary condition for the gas phase energy equation. The present numerical results for the gas temperature, water vapor mole fraction and hydrogen mole fraction are compared with the corresponding experimental data. In general, the agreement is very good especially in the first 105 millimeters. However, some differences are observed in the vicinity of the exit section of the rectangular channel. The numerical results show that the production of water vapor is very fast near the entrance section flowed by a much slower reaction rate. Gas phase ignition is noticed near the catalytic surface at a streamwise distance of about 120 mm. This gas-phase ignition manifests itself as a sudden increase in the mole fractions of OH, H and O.
The Innovation of Rapid Reconfigurable Position Fixture Based on Eccentric-Cams
Authors: Wang Mingdi , Zhong Kangmin , Cui Jinling
Published: July 2010

For the conventional fixture, it is usually less able to adapt to the changes of the size and the shape of the workpiece, but the modern mechanical products requires the update speed must be very fast, so the claming devices in machine tool have to have the increasing rapid-reaction capability. In order to meet this need in an economical way, the innovation idea of the rapid reconfigurable fixtures based on eccentric-cams have been introduced; the working principles and the calculating formulas of the devices are then given out. Through the analysis of the limit locations, the merit of strong adaptability to the size of the workpiece is found out. Furthermore, the components in these fixtures can be reused in different occasions conveniently, so this idea provides one economical method for the short delivery time in big production. Compared with the combined fixes, the rapid reconfigurable fixtures are more flexible and more economical.
Status of Biomass Combustion Technologies in China
Authors: Li Bin , Ma Shenghong
Published: July 2010

With the developing and increasing of the economy, China is faced with the pressure from economy increasing and shortage of energy. Chinese power and energy structure inclines to be diversified. With consideration of the environmental, economical and social benefit of renewable energy utilization, evidently, biomass will play great roles in the future alternative energies; in China, biomass power generation has developed rapidly in the past few years for its promising prospect. In this paper, the status, trend, and the potential of biomass firing power in China are discussed; the feasibility and the significance of the large-scaled biomass power generation technologies are investigated; a series of measurement to reach the goals are proposed herein.
Three-Dimensional Finite Element Analyses for Pyramidal Three-Roll Bending Process
Authors: Feng Zhengkun , Champliaud Henri , Dao Thien-My
Published: July 2010

Many applications of conical roll bending can be found in manufacturing industry, such as rolling a conical segment of a wind turbine tower or an alternative process of molding a large crown for a Francis turbine. This molding process could be achieved by assembling several conical segments. For the purpose of using cylindrical rolls or reusing the existing conical rolls of the kinematical conical roll bending process for non-kinematical conical roll bending process, attachments were proposed in order to reduce the velocity at the top edge of the plate. In contrast with a kinematical conical roll bending machine where no sliding exists between the plate and the rolls, the contact surface near the top edge of the plate of the three driving rolls of a non-kinematical conical roll bending machine slides on the plate due to the friction between the attachments and the plate. Therefore, the appropriate velocity at the top edge of the plate corresponding to that of the kinematical conical roll bending process can be obtained. This paper deals with the simulation analyses of the non-kinematical multi-pass conical roll bending process based on the finite element method, for example, the analyses of the applied force on the pressing roll. The components of the roll bending machine, such as the rolls and the attachments, etc. were assumed to be rigid bodies and the 4-node shell elements were used in the modeling. Bilinear material properties were used for the elasto-plasticity of the plate. Automatic node-surface contacts were chosen on the interfaces between the plate and the rigid bodies. The nonlinear equations which represent the structural dynamics with large displacement were resolved using explicit time integration. The simulations were performed under the well-known ANSYS/LS-DYNA environment. A well bent cone was obtained and compared very well with the ideal cone. The numerical simulation results show that the bent cone depends on the static and dynamic friction coefficients for a geometrical configuration with an appropriate span of the outer rolls.
Reducing Combustion Irreversibility Through Extreme Compression: Analyzing Device Performance
Authors: Miller Shannon L. , Svrcek Matthew N. , Wilson Joseph N. , LaCroix Olivier , Edwards Christopher F.
Published: July 2010

One promising technique for increasing the efficiency of combustion engines is to perform the reaction at extremely high compression ratios. To manage significantly higher temperatures and pressures, a new engine architecture is required. In addition, critical questions must be answered to address feasibility of operating at these extreme states. To investigate these questions, a single-shot, free-piston laboratory device was built, capable of achieving combustion at compression ratios of 100:1 and greater. This paper quantifies the combined heat- and mass-transfer losses present during air-compression experiments. Since these air-compression losses are also present during combustion experiments, quantifying these baseline operating losses, independent from additional losses during combustion, will help in assessing feasibility of the overall strategy as well as in identifying specific strategies for achieving higher efficiencies.
Effect of DLC Coating on Limiting Drawing Ratio of AZ31 Magnesium Alloy Sheet
Authors: Tsuji Y. , Yoshihara S. , Tsuda S. , Iriyama Y. , Nakano Y.
Published: July 2010

Magnesium alloys have several advantages that make them attractive for use in structural applications such as a superlight weight, high specific strength, ease of recycling and electromagnetic shielding capability. On the other hand, several disadvantages are associated with manufacturing using magnesium alloys such as the fact that it is practically impossible to apply conventional metal-forming techniques at room temperature without producing defects. Much effort, therefore, has recently been applied to improving the formability of magnesium-based alloys in order that they may realize their full potential. In this study, the methodology of coating the surface of a magnesium alloy with a diamond-like carbon (DLC) coating to increase the surface lubrication performance and for achieve deep drawability is discussed. The DLC acts as a lubricant during the forming process, thus reducing the deformation of the workpieces. Friction tests and deep-drawing tests were carried out to estimate the effect of the DLC coating by the formability of the magnesium alloy. We have compared the properties of non-lubricated blanks with those lubricated a DLC coating and the lubricants and MoS2. The coefficient of friction of the DLC-coated blank was approximately 0.16. Those of the non-lubricated blank and the blanks coated with GM100 and MoS2 were 0.41, 0.26, and 0.17 respectively. Thus, the DLC coating provides a similar or superior level of lubrication when compared with a conventional lubricant. The deep-drawing test was performed to obtain the limiting drawing ratio (LDR). For the DLC-coated blank, deep-drawing was possible at drawing ratio (DR) 2.2. On the other hand, the non-lubricated blank fractured at DR2.0. In the case of GM100 and MoS2, deep-drawing was successful at DR2.2 and DR2.3, respectively. In both friction and deep-drawing tests, the performance of DLC-coated workpieces was compared with that of workpieces coated with the conventional lubricants. The deep-drawing tests were carried out at 200 °C, and the formability of each blank was measured. It was concluded that the use of DLC-coated blanks produces an improvement in the formability of magnesium alloys compared with the use of conventional lubrication techniques.
Formability of AZ31 Magnesium Alloy Sheet in Dry Press Forming Using Diamond-Coated Dies
Authors: Tsuda S. , Yoshihara S. , Kataoka S.
Published: July 2010

Dry press forming which hasn’t used lubricants in the process is the attractive forming technique of zero emission for the lubricants. As one of the dry press forming techniques, the usage of dies coated with a chemical vapor deposition (CVD) diamond film, which are expected to be applied to forming tools owing to their high tribological properties, abrasion resistance and heat resistance, has been proposed. Magnesium alloys have attracted attention owing to their advantages over what such as, high specific strength and ease of recycling. However, they have intractable characteristics, and it is necessary to perform the forming technique at high temperature and to consider lubrication condition. In this study, diamond-coated dies were used in the deformation of magnesium alloy sheets without lubricants in press forming, and the formability of magnesium alloy and its effect on the surface texture of a formed-cup were investigated. Dry deep-drawing tests and dry ironing tests were carried out to estimate the effect of the diamond-coated dies on the formability of magnesium alloy sheets. Furthermore, the formability obtained using the above-mentioned tests was compared with that obtained in tests using non-lubricant dies with traditional lubricant. AZ31 magnesium alloy sheets (thickness: t0 = 0.5 mm) were deformed at 200 °C in dry deep-drawing tests. From the results, it was found that what can be deformed using diamond-coated dies. Moreover, a 20% reduction in drawing force was confirmed compared with the usage of the traditional lubricant (MoS2). Meanwhile, dry ironing tests were performed under conditions of 10% ironing ratio by a method similar to the dry deep-drawing tests. In general, the ironing process, which is the most difficult step in lubrication in sheet forming, has been enabled by the diamond coating technique. Furthermore, it was observed that the surface roughness of the formed-cup walls using the diamond-coated dies was 0.4 μmRz, and, 1.3 μmRz in case of MoS2. It was confirmed that the application of diamond-coated dies improved the surface roughness of the formed-cup. It produced an improvement in the formability of magnesium alloys compared with the traditional lubrication technique (use of MoS2). It was concluded that the validity of the use of diamond-coated dies became clear.
Response Surface Modeling and Optimization of Electro-Discharge Machining of Al/Al2O3p
Authors: Brahmankar P. K. , Patil N. G. , Navale L. G.
Published: July 2010

In this study, wire electrical discharge machining of aluminium matrix composites has been experimentally investigated. A metal matrix composite Al/Al2O3p/10% has been machined at various combinations of machining parameters such as pulse on-time, off-time, wire speed and wire tension. Empirical models have been developed to predict the cutting rate, surface roughness and kerf width of the machined composite material. The models were developed by using the technique of response surface methodology. The experiments were conducted by using carefully planned response surface design matrix (central composite design). The model predictions are in good agreement with the experimental results. The R2 values of the proposed cutting rate, and kerf width models are above 0.99 and 0.98 respectively, where as it is 0.95 for the surface roughness model. The pulse on-time was found to influence cutting rate and surface finish significantly. Kerf width was significantly affected by pulse on-time, off-time, wire speed, and wire tension. In addition, a model was developed to correlate the multiple performance characteristic called as grey relational grade and the process parameters. Thus, a new combination of response surface method and grey relational analysis is proposed. The grey relational grade was significantly affected by pulse on-time and off-time time. The R2 value for the grey relational grade model was 0.94. Optimal parameter setting was determined for the multiple performance characteristic. The improvement in cutting rate was more than 100% compared to the ‘0’ level experiments, with reasonably smooth surfaces and narrow kerf width.