bluuebunny/crossref_metadata_2025 huggingface dataset:
Is a first acute symptomatic seizure epilepsy? Mortality and risk for recurrent seizure
Authors: Hesdorffer Dale C. , Benn Emma K. T. , Cascino Gregory D. , Hauser W. Allen
Published: January 2009

Purpose:  To compare mortality and subsequent unprovoked seizure risk in a population‐based study of acute symptomatic seizure and first unprovoked seizure due to static brain lesions.

Methods:  We ascertained all first episodes of acute symptomatic seizure and unprovoked seizure due to central nervous system (CNS) infection, stroke, and traumatic brain injury (TBI). Subjects were residents of Rochester, Minnesota, identified through the Rochester Epidemiology Project’s records‐linkage system between 1/1/55 and 12/31/84. Information was collected on age, gender, seizure type, etiology, status epilepticus (SE), 30‐day and 10‐year mortality, and subsequent episodes of unprovoked seizure.

Results:  Two hundred sixty‐two individuals experienced a first acute symptomatic seizure and 148 individuals experienced a first unprovoked seizure, all due to static brain lesions. Individuals with a first acute symptomatic seizure were 8.9 times more likely to die within 30 days compared to those with a first unprovoked seizure [95% confidence intervals (CI) = 3.5–22.5] after adjustment for age, gender, and SE. Among 30‐day survivors, the risk of 10‐year mortality did not differ. Over the 10‐year period, individuals with a first acute symptomatic seizure were 80% less likely to experience a subsequent unprovoked seizure compared with individuals with a first unprovoked seizure [adjusted rate ratio (RR) = 0.2, 95% CI = 0.2–0.4].

Discussion:  The prognosis of first acute symptomatic seizures differs from that of first unprovoked seizure when the etiology is stroke, TBI, and CNS infection. Acute symptomatic seizures have a higher early mortality and a lower risk for subsequent unprovoked seizure. These differences argue against the inclusion of acute symptomatic seizures as epilepsy.
Preventing and treating posttraumatic seizures: The human experience
Authors: Temkin Nancy R.
Published: January 2009

Posttraumatic epilepsy presents an ideal target for prevention efforts. Traumatic brain injury (TBI) is common, characteristics that put people at high risk such as penetrating injury or subdural hematoma or provoked seizures are easily identified, and the latency between the injury and the onset of epileptic seizures is frequently short. Several drugs have been tested for their ability to prevent provoked seizures and epilepsy after TBI. We describe the design of those studies and their results. Phenytoin and carbamazepine significantly reduce the incidence of provoked seizures. Phenobarbital and the combination of phenobarbital and phenytoin also look promising for reducing provoked seizures, but small sample sizes in the studies evaluating these drugs do not allow definitive conclusions. None of the drugs studied (phenytoin, phenobarbital, their combination, carbamazepine, valproate, or magnesium) have shown reliable evidence that they prevent, or even suppress, epileptic seizures after TBI. For most of the regimens tested (the phenytoin/phenobarbital combination being the exception), the best estimate of effect is under a 25% reduction in posttraumatic seizures, well less than the 50% reduction most studies were designed to detect. The evaluation of the tested drugs has serious limitations, however, and antiepileptic drugs (AEDs) developed since 1980 and other compounds have barely been tested at all. Better understanding the process of epileptogenesis, testing treatments that demonstrate antiepileptogenic effects in the laboratory, and performing thorough preclinical and phase II evaluations before attempting definitive trials should greatly improve the chance of identifying ways to prevent posttraumatic epilepsy, providing the ultimate cure for this condition.
Posttraumatic epilepsy: The endophenotypes of a human model of epileptogenesis
Authors: Diaz‐Arrastia Ramon , Agostini Mark A. , Madden Christopher J. , Van Ness Paul C.
Published: January 2009

Posttraumatic epilepsy is a common complication of traumatic brain injury (TBI), occurring in up to 15–20% of patients with severe brain trauma. Trauma accounts for approximately 5% of chronic epilepsy in the community. Because it is a common condition, and because of the relatively short latency period between injury and onset of chronic seizures, posttraumatic epilepsy represents a good model to test antiepileptogenic therapies. However, several well‐conducted clinical trials have failed to demonstrate antiepileptogenic efficacy for several common anticonvulsants. Posttraumatic epilepsy can arise through a number of mechanisms, which often coexist within a single patient. Penetrating brain injury produces a cicatrix in the cortex and is associated with a risk of posttraumatic epilepsy of approximately 50%, whereas nonpenetrating head injury may produce focal contusions and intracranial hemorrhages, and is associated with a risk of posttraumatic epilepsy of up to 30%. Furthermore, closed head injury often produces diffuse concussive injury, with shearing of axons and selective damage to vulnerable brain regions, such as the hippocampus. The clinical, neurophysiologic, imaging, and neuropathologic features or epileptogenicity differ between these alternate mechanisms. It is likely that better understanding of the subtypes of epilepsy resulting from brain trauma will be required to successfully identify antiepileptogenic therapies.
Epilepsy following cortical injury: Cellular and molecular mechanisms as targets for potential prophylaxis
Authors: Prince David A. , Parada Isabel , Scalise Karina , Graber Kevin , Jin Xiaoming , Shen Fran
Published: January 2009

The sequelae of traumatic brain injury, including posttraumatic epilepsy, represent a major societal problem. Significant resources are required to develop a better understanding of the underlying pathophysiologic mechanisms as targets for potential prophylactic therapies. Posttraumatic epilepsy undoubtedly involves numerous pathogenic factors that develop more or less in parallel. We have highlighted two potential “prime movers”: disinhibition and development of new functional excitatory connectivity, which occur in a number of animal models and some forms of epilepsy in humans. Previous experiments have shown that tetrodotoxin (TTX) applied to injured cortex during a critical period early after lesion placement can prevent epileptogenesis in the partial cortical (“undercut”) model of posttraumatic epilepsy. Here we show that such treatment markedly attenuates histologic indices of axonal and terminal sprouting and presumably associated aberrant excitatory connectivity. A second finding in the undercut model is a decrease in spontaneous inhibitory events. Current experiments show that this is accompanied by regressive alterations in fast‐spiking γ‐aminobutyric acid (GABA)ergic interneurons, including shrinkage of dendrites, marked decreases in axonal length, structural changes in inhibitory boutons, and loss of inhibitory synapses on pyramidal cells. Other data support the hypothesis that these anatomic abnormalities may result from loss of trophic support normally provided to interneurons by brain‐derived neurotrophic factor (BDNF).

Approaches that prevent these two pathophysiologic mechanisms may offer avenues for prophylaxis for posttraumatic epilepsy. However, major issues such as the role of these processes in functional recovery from injury and the timing of the critical period(s) for application of potential therapies in humans need to be resolved.
Voices from the Field: How Exceptional Electronic Industrial Innovators Innovate
Authors: Griffin Abbie , Price Raymond L. , Maloney Matthew M. , Vojak Bruce A. , Sim Edward W.
Published: January 2009

This exploratory research uses in‐depth qualitative interviews to investigate how 11 exceptional innovators in the electronics industry initiated, created, and commercialized radical innovations in their firms. From the data, two initial frameworks emerged for how radical innovations were created by these individuals. Four themes emerged associated with what these innovators bring to the organization as an underpinning for being able to radically innovate. Additional themes emerged as to the process by which they innovate. Across the literatures of innovation, psychology, and management, creativity is discussed in terms of person, product, or process. This research samples on highly creative innovations (products) and finds that it appears that both person and process need to be considered in attaining radical innovation. One may not be able to consider separately the person who achieves radical innovation from the process he or she uses to achieve it. These exceptional innovators have specific personality characteristics that support radically creative behavior, supplemented by a perspective or worldview that focuses on having a business orientation yet also a somewhat idealistic attitude. They have prepared for innovation by studying deeply, within not just one primary technology topic but also a secondary or peripheral technology topic. In addition, they have prepared broadly, across technology, business, and markets. They are both extrinsically and intrinsically motivated to innovate. People communicating what problems are urgently important to them to be solved produce external motivation for the innovator, who is then intrinsically motivated to solve these people's problems by creating new products. In terms of how they innovate, these exceptional innovators are organizationally savvy and both understand and participate in the politics necessary to gain acceptance of and resources for their project. They use an innovation process that emphasizes the up‐front aspects of finding interesting problems, planning first before executing, and understanding customer needs in great detail. This allows them to generate insights into how to solve those problems profitably for the firm. Once they have obtained and validated their insights for solving the problem, they participate in the actual implementation of the concept to a commercialized product. However, this development aspect of innovating is not much spoken of, as if it is taken for granted. Finally, they actively disseminate knowledge and acceptance of the innovation postinvention.
Grp94 acts as a mediator of curcumin‐induced antioxidant defence in myogenic cells
Authors: Pizzo Paola , Scapin Cristina , Vitadello Maurizio , Florean Cristina , Gorza Luisa
Published: January 2009

Curcumin is a non‐toxic polyphenol with pleiotropic activities and limited bioavailability. We investigated whether a brief exposure to low doses of curcumin would induce in the myogenic C2C12 cell line an endoplasmic reticulum (ER) stress response and protect against oxidative stress. A 3‐hr curcumin administration (5–10 μM) increased protein levels of the ER chaperone Grp94, without affecting those of Grp78, calreticulin and haeme‐oxygenase‐1 (HO‐1). Exposure of cells to hydrogen peroxide 24 hrs after the curcumin treatment decreased caspase‐12 activation, total protein oxidation and translocation of NF‐κB to the nucleus, compared with untreated cells. Grp94 overexpression, achieved by means of either stable or transient trasfection, induced comparable cytoprotective effects to hydrogen peroxide. The delayed cytoprotection induced by curcumin acted through Grp94, because the curcumin‐induced increase in Grp94 expression was hampered by either stable or transient transfection with antisense cDNA; in these latter cells, the extent of total protein oxidation, as well as the translocation of NF‐κB to the nucleus, and the percentage of apoptotic cells were comparable to those observed in both curcumin‐untreated wild‐type and empty vector transfected cells. Defining the mechanism(s) by which Grp94 exerts its antioxidant defence, the determination of cytosolic calcium levels in C2C12 cells by fura‐2 showed a significantly reduced amount of releasable calcium from intracellular stores, both in conditions of Grp94 overexpression and after curcumin pre‐treatment. Therefore, a brief exposure to curcumin induces a delayed cytoprotection against oxidative stress in myogenic cells by increasing Grp94 protein level, which acts as a regulator of calcium homeostasis.
Impact of oral disease on quality of life in the US and Australian populations
Authors: Sanders Anne E. , Slade Gary D. , Lim Sungwoo , Reisine Susan T
Published: January 2009

Abstract –  The US National Health and Nutrition Examination Survey (NHANES 2003–2004) evaluated oral health quality of life for the first time using a previously untested subset of seven Oral Health Impact Profile (OHIP) questions, i.e. the NHANES‐OHIP.

Objectives:  (i) To describe the impact of dental conditions on quality of life in the US adult population; (ii) to evaluate construct validity and adequacy of the NHANES‐OHIP in NHANES 2003–2004 and a comparable Australian survey.

Methods:  In the cross‐sectional NHANES 2003–2004 survey of a nationally representative sample of US adults (n = 4907), prevalence was quantified as the proportion of adults who reported experiencing one or more impacts fairly often or very often within the past year. Construct validity was tested by comparing prevalence estimates across categories of sociodemographic, dental health and utilization characteristics known to vary in oral health. In 2002, Australian cross‐sectional survey of a nationally representative sample of adults (n = 2644), adequacy of the NHANES‐OHIP questions were tested with reference to a slightly modified version of the OHIP‐14 questions.

Results:  NHANES‐OHIP prevalence estimates were markedly similar in the United States (15.3%) and Australia (15.7%). In the US construct, validity was evidenced by higher NHANES‐OHIP scores among groups with greater levels of tooth loss, perceived treatment need and problem‐oriented visiting and with lack of private dental insurance and low income. In Australia, prevalence for the NHANES‐OHIP closely resembled prevalence estimates of the modified OHIP‐14. Both varied to a similar degree across levels of tooth loss, perceived treatment need, problem‐oriented visiting, and private dental insurance and income, demonstrating adequacy of the NHANES‐OHIP as a brief independent instrument.

Conclusions:  There was acceptable construct validity and adequacy of the NHANES‐OHIP questionnaire. In the United States, the impact of oral disease disproportionately affected disadvantaged groups, a finding that supports application of the US Healthy People 2010 major goals of improved quality of life and reduced health disparities.
Modulation of anger control in suicide attempters by TPH‐1
Authors: Baud P. , Perroud N. , Courtet P. , Jaussent I. , Relecom C. , Jollant F. , Malafosse A.
Published: January 2009

A genetic association between the tryptophan hydroxylase gene (TPH)‐1 A218C polymorphism and suicidal behaviour is supported by numerous case–control studies as well as recent meta‐analyses. Some data suggest that this polymorphism could also influence individual differences in anger‐related personality traits, a phenotype partially under genetic control and known to increase the risk of suicide ideation and attempt. The aim of the present study was to investigate whether the TPH‐1 A218C polymorphism affected anger‐related personality traits in suicide attempters (n = 544). We hypothesized that suicide attempters carrying the AA genotype would display different scores on a scale measuring anger‐related traits compared with suicide attempters carrying the CC genotype. Indeed, the dimension of Anger Control was significantly affected by the TPH‐1 A218C polymorphism: suicide attempters carrying the AA genotype scored significantly lower on the Anger Control subscale than suicide attempters carrying the AC and CC genotypes. This polymorphism did not display any influence on the other State‐Trait Anger Expression Inventory subscales. This result confirms our working hypothesis and suggests that the TPH‐1 genotype could confer a vulnerability to suicidal behaviour through a reduced capacity to control anger, which in turn may represent a common psychopathological and behavioural pathway to suicidal behaviour in an important subgroup of clinical subjects.
Do IRBs Pass the Minimal Harm Test?
Authors: Ceci Stephen J. , Bruck Maggie
Published: January 2009

We describe examples of institutional review board (IRB) actions that have delayed or thwarted research that could not conceivably be considered to pose more than minimal risk to participants. We propose three changes to improve the IRB process and reduce both human and financial costs.
What (and Where) Is the Ethical Code Concerning Researcher Conflict of Interest?
Authors: Greenwald Anthony G.
Published: January 2009

Decision makers are expected to identify and perhaps recuse themselves from actions that affect entities (such as relatives or corporations) to which their relationships create an appearance of conflict of interest. This article illustrates relationships that can create conflicts of interest for editors, grant decision makers, journal and grant reviewers, expert witnesses, and also for many researchers with method or theory commitments. The author urges psychology's professional associations to do what they now do either minimally or not at all: provide ethical guidelines that identify these conflicts and offer reasoned advice on managing them.
Minimally Sufficient Research
Authors: Peterson Christopher
Published: January 2009

Psychology would be improved if researchers stopped using complicated designs, procedures, and statistical analyses for the sole reason that they are able to do so. The present article reviews some of the classic studies in psychology, all of which are breathtakingly simple. The notion of minimally sufficient research is suggested as an ideal worth following. More generally, questions should dictate research methods and statistical analyses, not vice versa.
Two Is Better Than One
Authors: Kagan Jerome
Published: January 2009

Psychologists too often rely on only one source of evidence to affirm the validity of a construct. However, they usually do not know all the conditions that can produce the evidence they gather. Hence, the inference is often limited to the data gathered and does not generalize to other categories of information. Examples of this habit are presented along with the suggestion that all social scientists should affirm the utility of their concepts with more than one class of information.
Using New Interactive Media to Enhance the Teaching of Psychology (and Other Disciplines) in Developing Countries
Authors: Myers David G.
Published: January 2009

My idea for improving psychology responds to the challenge of teaching psychology in lower income, developing countries. With new Web-based e-books on the horizon, I suggest harnessing the Internet to deliver state-of-the-art, interactive, low-cost, locally adapted content to students who cannot afford books.
The Psychology of Referencing in Psychology Journal Articles
Authors: Safer Martin A. , Tang Rong
Published: January 2009

Citation statistics can affect major professional decisions, but little is known about how important a particular reference is to the citing document. We asked 49 psychologists to rate the importance of every reference in their own empirical paper and to indicate the primary citation reason. References cited for conceptual ideas or to justify methods and data analyses were regarded as more important than references cited for general background, limitations, or future research. The location, frequency, and length of a citation predicted its importance, but such relationships were weaker for self-citations. We make suggestions about referencing for authors, editors, and bibliographic database designers.
Are Social Scientists Harder on Their Colleagues Than Physical Scientists Were on Theirs in the Past? Commentary on Trafimow & Rice (2009)
Authors: Nickerson Raymond S.
Published: January 2009

Trafimow and Rice (2009; this issue) have written a thought-provoking article that addresses an important issue in a creative, informative, and engaging way. In a series of vignettes, the authors imagine how several of the better known developments of science might have fared if the manuscripts in which they were first described had been assessed according to the standards and predilections of current reviewers of manuscripts in the social sciences. In this commentary, I note points made by Trafimow and Rice with which I agree, mention some questions that the article raises that are important in my view, challenge the authors' assumption that contemporary social scientists generally treat the ideas of their colleagues more harshly than past physical scientists treated those of theirs, and express an opinion about the merits of the peer-review system as it currently functions in the social sciences. Although I acknowledge that the current system is far from perfect, I argue that it does a passably good job and question whether the reviews it produces are generally too harsh.
Loop Diuretics Can Cause Clinical Natriuretic Failure: A Prescription for Volume Expansion
Authors: Ali Syed S. , Olinger Chad C. , Sobotka Paul A. , Dahle Thom G.A. , Bunte Matthew C. , Blake Donnevan , Boyle Andrew J.
Published: January 2009

Ultrafiltration enhances volume removal and weight reduction vs diuretics. However, their differential impact on total body sodium, potassium, and magnesium has not been described. Fifteen patients with congestion despite diuretic therapy had urine electrolytes measured after a diuretic dose. Ultrafiltration was initiated and ultrafiltrate electrolytes were measured. The urine sodium after diuretics (60±47 mmol/L) was less than in the ultrafiltrate (134±8.0 mmol/L) (P=.000025). The urine potassium level after diuretics (41±23 mmol/L) was greater than in the ultrafiltrate (3.7±0.6 mmol/L) (P=.000017). The urine magnesium level after diuretics (5.2±3.1 mg/dL) was greater than in the ultrafiltrate (2.9±0.7 mg/dL) (P=.017). In acute decompensated heart failure patients with congestion despite diuretic therapy, diuretics are poor natriuretics and cause significant potassium and magnesium loss. Ultrafiltration extracts more sodium while sparing potassium and magnesium. The sustained clinical benefits of ultrafiltration compared with diuretics may be partly related to their disparate effects on total body sodium, potassium, and magnesium, in addition to their differential efficacy of volume removal.
Characterisation of Two New Reference Materials: STL‐1, the Stewart Lepidolite and ZA‐1, the Zapot Amazonite
Authors: Logan M. Amelia V. , Wise Michael A.
Published: January 2009

The analysis of granitic pegmatites still remains a challenge because suitable natural reference materials are scarce or not available. Two new reference materials were prepared at the Smithsonian Institution, to provide an avenue to pursue the geochemical analysis of micas and feldspars in granitic pegmatites: STL‐1, the Stewart lepidolite (NMNH 174041) and ZA‐1, the Zapot amazonite (NMNH 174042). STL‐1 was prepared from lepidolite collected from the lithium‐rich Stewart pegmatite, San Diego County, California (33°22′52′’N, 117°03′41′’W). ZA‐1 was prepared from an amazonite from the topaz‐bearing Zapot pegmatite, Mineral County, Nevada, (38° 41’N, 118 °33’W). The results of this study indicated that STL‐1 and ZA‐1 are homogeneous and could be used as reference materials that would allow the expansion of calibration curves in XRF analysis up to 16000 μg g−1 for Rb, 2000 μg g−1 for Cs and 100 μg g−1 for Tl. STL‐1 and ZA‐1 also contain unusually high concentrations of Ga and Tl, and STL‐1 of Nb.
A Synthetic Germanium‐Bismuth Glass for the Coarse Mass Calibration of SIMS Instruments
Authors: Wiedenbeck Michael , Schulze Dina , Veksler Ilya
Published: January 2009

This short technical note describes a simple technique for synthesising an optimised binary glass for performing coarse mass table calibrations of secondary ion mass spectrometers. A Ge‐Bi glass doped with five selected trace elements was used to anchor the entire mass table up to m/z ≥ 209 at an accuracy of < 0.5 dalton. Using this material it has been possible to calibrate coarsely the mass table of a Cameca ims 6f instrument in less than five minutes, thereby greatly simplifying the switch from low mass range to high mass range measurements. Although not suitable for the quantification of geological materials, the ease of synthesis and its utility for rapidly performing what is an otherwise time consuming process makes this material a useful tool for SIMS instruments which offer a multiple mass range capability.
Proposed New Fatigue Design Curves for Carbon and Low-Alloy Steels in
High Temperature Water
Authors: O’Donnell William J. , O’Donnell William John , O’Donnell Thomas P.
Published: January 2009

High temperature (>300°F, 149°C) water has been found to greatly accelerate fatigue crack growth rates in carbon and low-alloy steels. Current ASME Code fatigue design curves are based entirely on data obtained in air. While a factor of 2 on life was applied to the air data to account for environmental effects, the actual effects have been found to be an order of magnitude greater in the low-cycle regime. A great deal of work has been carried out on these environmental effects by talented investigators worldwide. The ASME Code Subgroup on Fatigue Strength has been working for 20years on the development of new fatigue design methods and curves to account for high temperature water environmental effects. This paper presents an overview of the data and analyses used to formulate proposed new environmental fatigue design curves, which maintain the same safety margins as existing Code fatigue design curves for air environments, and a historical summary of ASME Code Work in this field.
Leakage Predictions for Static Gasket Based on the Porous Media Theory
Authors: Jolly Pascal , Marchand Luc
Published: January 2009

In the present work, the annular static gaskets are considered as porous media and Darcy’s law is written for a steady radial flow of a compressible gas with a first order slip boundary conditions. From this, a simple equation is obtained that includes Klinkenberg’s intrinsic permeability factor kv of the gasket and the Knudsen number Kn′o defined with a characteristic length ℓ. The parameters kv and ℓ of the porous gasket are calculated from experimental results obtained with a reference gas at several gasket stress levels. Then, with kv and ℓ, the inverse procedure is performed to predict the leakage rate for three different gases. It is shown that the porous media model predicts leak rates with the same accuracy as the laminar-molecular flow (LMF) model of Marchand et al. However, the new model has the advantage of furnishing phenomenological information on the evolution of the intrinsic permeability and the gas flow regimes with the gasket compressive stress. It also enables quick identification of the part of leakage that occurs at the flange-gasket interface at low gasket stresses. At low gas pressure, the behavior of the apparent permeability diverges from that of Klinkenberg’s, indicating that the rarefaction effect becomes preponderant on the leak.
Adaptive NC Path Generation From Massive Point Data With Bounded Error
Authors: Zhang Dongdong , Yang Pinghai , Qian Xiaoping
Published: January 2009

This paper presents an approach for generating curvature-adaptive finishing tool paths with bounded error directly from massive point data in three-axis computer numerical control (CNC) milling. This approach uses the moving least-squares (MLS) surface as the underlying surface representation. A closed-form formula for normal curvature computation is derived from the implicit form of MLS surfaces. It enables the generation of curvature-adaptive tool paths from massive point data that is critical for balancing the trade-off between machining accuracy and speed. To ensure the path accuracy and robustness for arbitrary surfaces where there might be an abrupt curvature change, a novel guidance field algorithm is introduced. It overcomes potential excessive locality of curvature-adaptive paths by examining the neighboring points’ curvature within a self-updating search bound. Our results affirm that the combination of curvature-adaptive path generation and the guidance field algorithm produces high-quality numerical control (NC) paths from a variety of point cloud data with bounded error.
Mechanical Analysis and Optimal Design for Carbon Fiber Resin Composite Wound Hydrogen Storage Vessel With Aluminum Alloy Liner
Authors: Zheng Chuanxiang , Lei Shaohui
Published: January 2009

The carbon fiber resin composite (CFRC) wound high-pressure vessel is the key equipment of high-pressure hydrogen storage technology. High pressure includes high energy in operation, so it is important to analyze the mechanics of this type of vessel. The constitutive performance of CFRC wound layer is anisotropic, and the layer arrangement is complexity, so it is difficult for mechanics analysis on a cylinder. Considering that the internal pressure in a cylinder is loaded by the aluminum alloy liner and the CFRC wound layers together, two models are built: The first model is the cylinder loaded by internal pressure in the hoop direction only. In this model, total hoop direction load is distributed into every layer under internal pressure. The second model is the cylinder loaded with the internal pressure on axial direction only. In this model, total axial load is distributed into all cylinders under internal pressure. Taking the boundary condition of continuous displacement between layers into account, a group of equations is built. From the equations, we can obtain the solutions of the internal pressures in hoop direction and axial direction loaded by every layer. After stresses are obtained, the optimal design can be done through this method. An example is given.
Force Modeling in Laser-Assisted Microgrooving Including the Effect of Machine Deflection
Authors: Singh Ramesh , Melkote Shreyes N.
Published: January 2009

Laser assisted mechanical micromachining is a process that utilizes highly localized thermal softening of the material by continuous wave laser irradiation applied simultaneously and directly in front of a miniature cutting tool in order to produce micron scale three-dimensional features in difficult-to-machine materials. The hybrid process is characterized by lower cutting forces and deflections, fewer tool failures, and potentially higher material removal rates. The desktop-sized machine used to implement this process has a finite stiffness and deflects under the influence of the cutting forces. The deflections can be of the same order of magnitude as the depth of cut in some cases, thereby having a negative effect on the dimensional accuracy of the micromachined feature. As a result, selection of the laser and cutting parameters that yield the desired reduction in cutting forces and deflection, and consequently an improvement in dimensional accuracy, requires a reliable cutting force model. This paper describes a cutting force model for the laser-assisted microgrooving process. The model accounts for the effect of elastic deflection of the machine X-Y stages on the forces and accuracy of the micromachined feature. The model combines an existing slip-line field based force model with a finite element based thermal model of laser heating and a constitutive material flow stress model to account for thermal softening. Experiments are carried out on H-13 steel (42 HRC (hardness measured on the Rockwell ‘C’ scale)) to validate the force model. The effects of process parameters, such as laser power and cutting speed, on the forces are also analyzed. The model captures the effect of thermal softening and indicates a 66% reduction in the shear flow stress at 35 W laser power. The cutting force and depth of cut prediction errors are less than 20% and 10%, respectively, for most of the cases examined.
Pressure Drop During Two-Phase Flow of R134a and R32 in a Single Minichannel
Authors: Cavallini Alberto , Del Col Davide , Matkovic Marko , Rossetto Luisa
Published: January 2009

Condensation in minichannels is widely used in air-cooled condensers for the automotive and air-conditioning industry, heat pipes, and compact heat exchangers. The knowledge of pressure drops in such small channels is important in order to optimize heat transfer surfaces. Most of the available experimental work refers to measurements obtained within multiport smooth extruded tubes and deal with the average values over the number of parallel channels. In this context, the present authors have set up a new test apparatus for heat transfer and fluid flow studies in single minichannels. This paper presents new experimental frictional pressure gradient data, relative to single-phase flow and adiabatic two-phase flow of R134a and R32 inside a single horizontal minitube, with a 0.96 mm inner diameter and with not-negligible surface roughness. The new all-liquid and all-vapor data are successfully compared against predictions of single-phase flow models. Also the two-phase flow data are compared against a model previously developed by the present authors for adiabatic flow or flow during condensation of halogenated refrigerants inside smooth minichannels. Surface roughness effects on the liquid-vapor flow are discussed. In this respect, the friction factor in the proposed model is modified, in order to take into consideration also effects due to wall roughness.
Multicomponent Energy Conserving Dissipative Particle Dynamics: A General Framework for Mesoscopic Heat Transfer Applications
Authors: Chaudhri Anuj , Lukes Jennifer R.
Published: January 2009

A multicomponent framework for energy conserving dissipative particle dynamics (DPD) is presented for the first time in both dimensional and dimensionless forms. Explicit definitions for unknown scaling factors that are consistent with DPD convention are found by comparing the present, general dimensionless governing equations to the standard DPD expressions in the literature. When the scaling factors are chosen based on the solvent in a multicomponent system, the system of equations reduces to a set that is easy to handle computationally. A computer code based on this multicomponent framework was validated, under the special case of identical components, for one-dimensional transient and one- and two-dimensional steady-state heat conduction in a random DPD solid. The results, which compare well with existing DPD works and with analytical solutions in one and two dimensions, show the promise of energy conserving DPD for modeling heat transfer at mesoscopic length scales.
Image Fusion for Infrared Thermography and Inspection of Pressure Vessel
Authors: Tian Yu-Peng , Zhou Ke-Yin , Feng Xiaowei , Yu Sheng-Lin , Liang Hua , Liang Bing
Published: January 2009

Infrared thermography is a nondestructive evaluation method with an increasing span of applications. In this paper the pixel-level image fusion of infrared light and visible light image for infrared thermography and its application in nondestructive testing (NDT) of pressure vessel are studied. First in the image fusion, different mode image registration has been done based on feature corners. The corners and curves relative to each corner are extracted using the curvature scale space method. A new shape context descriptor for each corner is computed as the criterion to match the corners. Marks can then be added to pick up the corners, especially if there are no distinct matching feature corners between the different mode images. Two fusion methods, contrast modulation and transparent fusion, are introduced to fuse the visual and infrared light images. The experimental results show that the methods are good for pixel-level image fusion. Finally the method is applied to inspection of pressure vessel. The research indicates that image fusion for infrared thermography can facilitate defect location and interpretation of inspection results.
An Efficient Computing Explicit Method for Structural Dynamics
Authors: Chang Shuenn-Yih
Published: January 2009

An integration algorithm, which integrates the most important advantage of explicit methods of the explicitness of each time step and that of implicit methods of the possibility of unconditional stability, is presented herein. This algorithm is analytically shown to be unconditionally stable for any linear elastic and nonlinear systems except for the instantaneous stiffness hardening systems with the instantaneous degree of nonlinearity larger than 43 based on a linearized stability analysis. Hence, its stability property is better than the previously published algorithm (Chang, 2007, “Improved Explicit Method for Structural Dynamics,” J. Eng. Mech., 133(7), pp. 748–760), which is only conditionally stable for instantaneous stiffness hardening systems although it also possesses unconditional stability for linear elastic and any instantaneous stiffness softening systems. Due to the explicitness of each time step, the possibility of unconditional stability, and comparable accuracy, the proposed algorithm is very promising for a general structural dynamic problem, where only the low frequency responses are of interest since it consumes much less computational efforts when compared with explicit methods, such as the Newmark explicit method, and implicit methods, such as the constant average acceleration method.
Development of Maximum Secondary Creep Strain Method for Lifetime of HDPE Pipes
Authors: Cheng Cunjiang , Widera G. E. Otto
Published: January 2009

Considering only the primary and secondary creep stages of high-density polyethylene (HDPE) material, a maximum secondary creep strain method (MSCS) and formula to calculate the maximum secondary creep strain has been developed based on existing test data and the creep law. Since the tertiary creep stage has a very short lifetime compared with the primary and secondary stages, it is reasonable to assume that rupture will occur once the creep strain reaches the maximum secondary creep strain. The implicit method of the finite element analysis software, LS-DYNA (1998, LS-DYNA Theoretical Manual, Livermore Software Technology Corporation), is employed to determine the HDPE pipe primary creep process using an effective numeric algorithm (Whirley and Henshall, 1992, “Creep Deformation Structural Analysis Using an Efficient Numerical Algorithm,” Int. J. Numer. Methods Eng., 35, pp. 1427–1442) followed by a formula to determine the secondary creep process. The expression for the overall lifetime of the HDPE pipes is then derived. Based on the agreement between the numerical and test results, it is concluded that the MSCS method can accurately predict the long-term hydrostatic strength of a HDPE pipe.
Simplified Limit Load Determination Using the mα-Tangent Method
Authors: Seshadri R. , Hossain M. M.
Published: January 2009

Limit load determination of mechanical components and structures by the mα-tangent method is proposed herein. The proposed technique is a simplified method that enables rapid determination of limit loads for a general class of mechanical components and structures. The method makes use of statically admissible stress field based on a linear elastic finite element analysis to estimate the limit loads. The method is applied to a number of mechanical component configurations and the results compare well with those obtained by the corresponding elastic-plastic finite element analyses results.
Applying Thermodynamics in Search of Superior Engine Efficiency
Authors: Amann Charles A.
Published: January 2009

Historically, a succession of thermodynamic processes has been used to idealize the operating cycles of internal combustion engines. In this study, the 256 possible combinations of four reversible processes – isentropic, isothermal, isochoric, and isobaric – are surveyed in search of cycles promising superior thermal efficiency. Regenerative cycles are excluded. The established concept of the air-standard cycle, which mimics the internal combustion engine as a closed-cycle heat engine, is used to narrow the field systematically. The approach relies primarily on graphical interpretation of approximate temperature-entropy diagrams and is qualitative only. In addition to identifying the cycles offering the greatest efficiency potential, the compromise between thermal efficiency and mean effective pressure is addressed.
Application of Over-Expansion Cycle to a Larger Gasoline Engine With Late-Closing of Intake Valves
Authors: Shiga Seiichi , Nishida Kenji , Yagi Shizuo , Miyashita Youichi , Yuzawa Yoshiharu , Nakamura Hisao , Ishima Tsuneaki , Obokata Tomio , Araki Mikiya
Published: January 2009

This paper presents further investigation into the effect of over-expansion cycle with late-closing of intake valves on the engine performance in gasoline engines. A larger single-cylinder test engine with the stroke volume of 650 cc was used with four kinds of expansion ratio (geometrical compression ratio) from 10 to 25 and four sets of intake valve closure (I.V.C.) timings from 0 to 110 deg C.A. ABDC. Late-closing has an effect of decreasing the pumping work due to the reduction of intake vacuum, althogh higher expansion ratio increases the friction work due to the average cylinder pressure level. Combining the higher expansion ratio with the late-closing determines the mechanical efficiency on the basis of these two contrastive effects. The indicated thermal efficiency is mostly determined by the expansion ratio and little affected by the nominal compression ratio. The value of the indicated thermal efficiency reaches to 48% at most which is almost comparable with the value of diesel engines. The improvement of both indicated and brake thermal efficiency reaches to 16% which is much higher than ever reported by the authors. A simple thermodynamic calculation could successfully explain the behavior of the indicated thermal efficiency. The brake thermal efficiency could also be improved due to the increase in both mechanical and indicated efficiencies.
Detailed Results for Nitric Oxide Emissions as Determined From a Multiple-Zone Cycle Simulation for a Spark-Ignition Engine
Authors: Caton Jerald A.
Published: January 2009

A thermodynamic cycle simulation was developed for spark-ignition engines which included a formulation using multiple zones for the combustion process and the capability to compute the net nitric oxide (NO) change due to the “thermal” formation mechanism. This simulation was used to complete analyses for a commercial, 5.7 l spark-ignition V-8 engine operating at a part load operating condition at 1400 rpm with an equivalence ratio of 1.0. The engine possessed a compression ratio of 8.1:1, and had a bore and stroke of 101.6 and 88.4 mm, respectively. At the base case conditions, the nitric oxide emissions were 15.7 g/bhp-hr (2903 ppm). The effects of equivalence ratio, combustion duration, spark timing, exhaust gas recirculation, compression ratio, speed and load on nitric oxide changes were examined. Results for instantaneous nitric oxide as a function of crank angle are presented. The use of an adiabatic zone was shown to dramatically increase the nitric oxide levels relative to using the burned gas temperature. For the base case, almost 50% more nitric oxide was computed using the adiabatic temperature relative to the burned gas temperature. The importance of gas temperature, cylinder gas pressure, and composition is illustrated.
ME´RIME´E: A Simulation Software to Study Diesel Engines Used for Military Propulsion
Authors: Tauzia Xavier , Chesse Pascal , Hetet Jean-Franc¸ois , Bonin Arnaud
Published: January 2009

The design and development of internal combustion engines, and by extension of complete powertrains for ground vehicles, constitute a particularly complex, costly and time consuming task. As a result, numerical simulation is now commonly used by engine manufacturers and vehicle designers in addition to test bench experiments. Engine simulation codes can be divided into three main categories, with very different objectives and levels of complexity: CFD codes, thermodynamic codes and real time codes. This paper presents the MERIMEE simulation code, which belongs to the second category (MERIMEE is the French acronym for Computer Research and Study Model for Engines and their Equipment). Jointly developed by Ecole Centrale de Nantes (for the models) and the CS-SI Company (for the software development) it is used by ETAS (French Army) for the development and study of complete powertrains designed for military ground propulsion. The main models used to simulate the engine behavior are first briefly described. Then, the software architecture, the interface as well as the programming and numerical aspects are described. Finally, some significant results are shown and compared with experimental data. They deal with steady state and transient engine behavior in addition to the evaluation of pollutant emissions.
Intake Turbulence Generated by a Steady Valve-Cylinder Flow
Authors: Bailey Gearle , Kuhlman John
Published: January 2009

Axial and swirl velocities have been measured for steady axisymmetric flow in a cylinder past a fixed intake valve located on the cylinder centerline, for two different intake port geometries and two valve lifts, in order to study the effects of swirl and valve lift on turbulence generation. Both Laser Doppler Anemometry (LDA) and Constant Temperature Anemometry (CTA) velocity measurements were obtained. The cylinder diameter was 82.6 mm, cylinder height was 114.3 mm, and the centrally located valve had a diameter of 41.9 mm. The LDA mean axial velocity data indicated a conical jet issuing from the valve, and a recirculating toroidal vortex above the valve for each case. Also, for the swirl intake cases, the swirl mean velocity in the toroidal vortex increased linearly with radius. Axial fluctuation velocities were about 1 m/sec away from the conical jet, for both valve lifts and both inlet flow geometries. In the conical jet, axial fluctuation velocities of 2–2.5 m/sec were observed. The swirl fluctuation was consistently lower than the axial fluctuation. The swirl inlet increased the magnitude of the swirl fluctuation in the conical jet.
An Analysis of the Simplified Two-Mass System of the Connecting Rod in Spark Ignition Engines
Authors: Stanley Richard
Published: January 2009

Replacing the connecting rod with a lumped two-mass system causes an error, which influences the inertia rolling moment, the thrust force between the piston and the cylinder liner, and the loading on the main bearings. Dimensionless relationships have been found that relate the inertia error due to the connecting rod simplification (the inertia error) to the errors of the forces and moments that are created by it. Additionally, the results of a statistical study of 19 SI connecting rods indicate that the mass moment of inertia of the two mass system is −2.65% to 22% higher than that the experimentally measured moment of inertia of the connecting rod, with an average error value of 9.65%.
Cranktrain Simulation of a Natural Gas Engine/Compressor
Authors: Thomassy Fernand A.
Published: January 2009

Advancing simulation technologies are making it possible for engineers to construct models of increasing complexity and fidelity. Southwest Research Institute (SwRI®) has investigated integrated analysis techniques that account for the dynamic interaction of cylinder load, hydrodynamic bearing orbits and flexible structural components in a time-based multi-body structural simulation. Misalignment of the main bearing bore is also simulated to investigate a condition that affects this type of mechanical system. This paper describes general modeling techniques implemented in ADAMS/Engine and how the component models influence the prediction of crankshaft stress through simulation of an HBA-6 engine/compressor. The HBA-6 is one of a class of reciprocating compressors used in the gas pipeline and process industries. It has a unique layout of power and compressor cylinders that helps to highlight the robustness of the simulation technique.