bluuebunny/crossref_metadata_2025 huggingface dataset:
Severe dental fluorosis and jowar consumption in Karnataka, India
Authors: Chandrashekar Janakiram , Thankappan K. R. , Sundaram K. R.
Published: July 2010

Chandrashekar J, Thankappan KR, Sundaram KR. Severe dental fluorosis and jowar consumption in Karnataka, India. Community Dent Oral Epidemiol 2010; 38: 559–567. © 2010 John Wiley & Sons A/S

Abstract – Introduction:  Dental fluorosis is a major public health problem in 17 states of India. Earlier studies have reported that Jowar (a type of millet) consumption interacts with fluoride (F) in the body and enhances fluorosis. We conducted this study to determine the association between jowar consumption and severity of dental fluorosis.

Methods:  A community based case control study was carried out in villages having different F levels (low, medium, and high) in drinking water in North Karnataka, India. 352 school Children (12–15 years, male 58%) with severe dental fluorosis classified by Thylstrup & Fejerskov Index (1988) were selected as cases. 428 school children (12–15 years, male 48.8%) with no dental fluorosis were selected randomly from the same area as controls. Exposure ascertainment of jowar consumption was done by 24‐h diet recall and food frequency questionnaire. Ion selective electrode method was used to estimate the F level in spot urine samples of subjects and in drinking water. Multiple logistic regression analysis was done using SPSS V. 11.01

Results:  Children who consumed jowar had 2.67 times more chance of getting severe dental fluorosis compared to those who did not [Odds Ratio (OR) 2.67, CI 1.98–3.62]. Children from high F level villages (OR 1.91, CI 1.27–2.85) had higher odds of severe dental fluorosis compared to children from medium and low F level villages. Daily jowar consumers (OR 2.14, CI 1.64–3.09) and weekly consumers (OR 1.68, CI 1.31–3.45) had higher risk for dental fluorosis compared to non jowar consumers. Children who started consuming jowar before 8 years of age had significantly higher proportion of severe dental fluorosis compared to their counterparts. Urinary F excretion among jowar consumers was significantly lower than non‐jowar consumers.

Conclusions:  Jowar consumption was positively associated with severity of dental fluorosis in this population.
Expression Analysis of miRNAs and Highly‐expressed Small RNAs in Two Rice Subspecies and their Reciprocal Hybrids
Authors: Chen Fangfang , He Guangming , He Hang , Chen Wei , Zhu Xiaopeng , Liang Manzhong , Chen Liangbi , Deng Xing Wang
Published: July 2010

Heterosis, or hybrid vigor, is the phenomenon whereby progeny of two inbred lines exhibit superior agronomic performance compared with either parent. We analyzed the expression of miRNAs and highly expressed small RNAs (defined according to Solexa sequencing results) in two rice (Oryza sativa) subspecies (japonicacv. Nipponbare andindicacv. 93‐11) and their reciprocal hybrids using microarrays. We found that of all the 1141 small RNAs tested, 140 (12%, 140 of 1141) and 157 (13%, 157 of 1141) were identified being significantly differentially expressed in two reciprocal hybrids, respectively. All possible modes of action, including additive, high‐ and low‐ parent, above high‐ and below low‐parent modes were exhibited. Both F1 hybrids showed non‐additive expression patterns, with downregulation predominating. Interestingly, 15 miRNAs displayed stark opposite expression trends relative to mid‐parent in reciprocal hybrids. Computational prediction of targets of differentially expressed miRNAs showed that they participated in multifaceted developmental pathways, and were not distinguishable from the targets of non‐differentially expressed miRNAs. Together, our findings reveal that small RNAs play roles in heterosis and add a new layer in the understanding and exploitation of molecular mechanisms of heterosis.
Batch and Column Experiments to Support Heavy Metals (Cu, Zn, and Mn) Transport Modeling in Alluvial Sediments Between the Mogan Lake and the Eymir Lake, Gölbaşı, Ankara
Authors: Dişli E.
Published: July 2010

This article describes laboratory batch sorption and column transport experiments that were conducted using heterogeneous alluvial sediments with a wide physical characteristic from wells, located between Lake Mogan and Lake Eymir, Gölbaşı, Ankara. The batch sorption experiment was conducted in two separate systems, that is, single and multicomponents. Single batch experiment was performed to determine equilibrium condition between the heavy metal ions and the soil adsorption sites. The sorption isotherms data from multibatch experiments were used to calculate the sorption parameters. Single batch experiment indicated that equilibrium was attained within 9 days from the start of the sorption test. As a result of multicomponents batch experiments, for Zn and Mn, the sorption process was well described by the Freundlich or Langmuir isotherm model, whereas sorption of Cu was better described by the linear isotherm model. The Kd of Cu were found to be highest in soil 1 (32550.350 L kg−1) and lowest in soil 5 (18170.76 L kg−1). The maximum and minimum sorption capacity values for Zn were found to be in soil 1 (10985.148 mg kg−1) and in soil 2 (8597.14 mg kg−1) units, respectively. [Correction added after online publication 15 July, 2010: In the preceding sentence, the words “minimum” and “maximum” were initially switched.] Similarly, soil 1 (7587.391 mg kg−1) and soil 5 (4908.695 mg kg−1) units provided the maximum and minimum values for Mn. In the column experiments, flow and tracer transport was studied under saturated conditions using conservative tracer to determine the transport parameters. Transport parameter values were obtained by curve‐fitting using the nonlinear least‐squares optimization code CXTFIT. Results of the column experiments indicated that the dispersivity values obtained for soil samples were in the range of 0.024 to 1.13 cm.
Assessment of flipper tag site healing in gray seal pups using thermography
Authors: Paterson W. , Pomeroy P. P. , Sparling C. E. , Moss S. , Thompson D. , Currie J. I. , McCafferty D. J.
Published: July 2010

Abstract

Infrared thermography was used to monitor the healing process at flipper tag sites in gray seal (Halichoerus grypus) pups. We tested the hypothesis that tagging would result in a rise in surface temperature associated with tag site healing processes compared with adjacent untagged areas of the flipper. Prior to tagging thermal images were recorded of the dorsal side of hind flippers of pups tagged in early lactation (n= 20) and at weaning (n= 19) on the Isle of May, Scotland (56°11′N, 02°33′W) from October to December 2008. Pups tagged in early lactation were sampled again at late lactation, at weaning and then every 3 d for an average of 29 d post‐tagging while pups tagged at weaning were sampled every 3 d for an average of 17 d post‐tagging. Tag sites were also scored for signs of infection or swelling at each sampling. Results showed that (1) small temperature increases associated with wound healing processes around the tag site returned to pre‐tagging levels before animals leave the island and (2) there was little evidence of tagging‐related infections or tag loss irrespective of age at tagging.
Phytase Activity from Lactobacillus spp. in Calcium‐Fortified Soymilk
Authors: Tang Anne Lise , Wilcox Gisela , Walker Karen Z. , Shah Nagandra P. , Ashton John F. , Stojanovska Lily
Published: July 2010

Abstract:  The presence of phytate in calcium‐fortified soymilk may interfere with mineral absorption. Certain lactic acid bacteria (LAB) produce the enzyme phytase that degrades phytates and therefore may potentially improve mineral bioavailability and absorption. This study investigates the phytase activity and phytate degradation potential of 7 strains of LAB including: Lactobacillus acidophilus ATCC4962, ATCC33200, ATCC4356, ATCC4161, L. casei ASCC290, L. plantarum ASCC276, and L. fermentum VRI‐003. Activity of these bacteria was examined both in screening media and in calcium‐fortified soymilk supplemented with potassium phytate. Most strains produced phytase under both conditions with L. acidophilus ATCC4161 showing the highest activity. Phytase activity in fortified soymilk fermented with L. acidophilus ATCC4962 and L. acidophilus ATCC4161 increased by 85% and 91%, respectively, between 12 h and 24 h of fermentation. All strains expressed peak phytase activity at approximately pH 5. However, no phytate degradation could be observed.
Inhibition of Citrus Fungal Pathogens by Using Lactic Acid Bacteria
Authors: Gerez C.L. , Carbajo M.S. , Rollán G. , Torres Leal G. , Font de Valdez G.
Published: July 2010

Abstract:  The effect of lactic acid bacteria (LAB) on pathogenic fungi was evaluated and the metabolites involved in the antifungal effect were characterized. Penicillium digitatum (INTA 1 to INTA 7) and Geotrichum citri‐aurantii (INTA 8) isolated from decayed lemon from commercial packinghouses were treated with imazalil and guazatine to obtain strains resistant to these fungicides. The most resistant strains (4 fungal strains) were selected for evaluating the antifungal activity of 33 LAB strains, among which only 8 strains gave positive results. The antifungal activity of these LAB strains was related to the production of lactic acid, acetic acid, and phenyllactic acid (PLA). A central composite design and the response surface methodology were used to evaluate the inhibitory effect of the organic acids produced by the LAB cultures. The antifungal activity of lactic acid was directly related to its concentration; however, acetic acid and PLA showed a peak of activity at 52.5 and 0.8 mM, respectively, with inhibition rates similar to those obtained with Serenade® (3.0 ppm) imazalil (50 ppm) and guazatine (50 ppm). Beyond the peak of activity, a reduction in effectiveness of both acetic acid and PLA was observed. Comparing the inhibition rate of the organic acids, PLA was about 66‐ and 600‐fold more effective than acetic acid and lactic acid, respectively. This study presents evidences on the antifungal effect of selected LAB strains and their end products. Studies are currently being undertaken to evaluate the effectiveness in preventing postharvest diseases on citrus fruits.
Characterization by Volatile Compounds of Microbial Deep Spoilage in Iberian Dry‐Cured Ham
Authors: Martín Alberto , Benito María J. , Aranda Emilio , Ruiz‐Moyano Santiago , Córdoba Juan J. , Córdoba María G.
Published: July 2010

Abstract:  In the present study, volatile compounds of spoiled dry‐cured Iberian ham with deep spoilage or “bone taint” were analyzed and correlated with level of spoilage and the microorganisms detected. Volatile compounds extracted by a solid phase micro‐extraction technique were assayed by gas chromatography/mass spectrometry. The spoiled hams were evaluated sensorially, and the correlations among volatile compounds, spoilage level, and microbial counts were studied. The spoiled hams had higher concentrations of hydrocarbons, alcohols, acids, esters, pyrazines, sulfur compounds, and other minor volatile compounds than unspoiled hams. The sensorial analysis showed that the spoilage level of hams correlated with several volatile compounds, most of them associated with Gram‐positive catalase positive cocci and Enterobacteriaceae counts. Cyclic compounds such as cyclohexanone, some ethers, and pyrazines should be considered as indicators to monitor incipient microbial deep spoilage in the elaboration of this meat product.
Social Context Influences on Children’s Rejection by Their Peers
Authors: Mikami Amori Yee , Lerner Matthew D. , Lun Janetta
Published: July 2010

Abstract—Peer rejection has gained much attention in recent years, due to repeated findings that negative peer experiences in childhood predict adjustment difficulties in adolescence and adulthood. The dominant conceptualization within developmental psychology has overwhelmingly focused on deficits within rejected children that contribute to their difficulties and has neglected contextual factors in the peer group setting that may also influence peer rejection. This article reviews growing evidence that the social context in which peer interactions occur does affect children’s liking or disliking of peers and argues that a complete model of peer rejection will be obtained only through understanding influences of social contexts. Implications for improving existing peer‐rejection interventions and for public policy are discussed.
From Racial Discrimination to Substance Use: The Buffering Effects of Racial Socialization
Authors: Neblett Jr. Enrique W. , Terzian Mary , Harriott Valencia
Published: July 2010

Abstract— The experience of race‐based discrimination may place African American youth at risk for substance use initiation and substance use disorders. This article examines the potential of parental racial socialization—a process by which parents convey messages to their children about race—to protect against the impact of racial discrimination on substance use outcomes. Focusing on stress as a major precipitating factor in substance use, the article postulates several possible mechanisms by which racial socialization might reduce stress and the subsequent risk for substance use. It discusses future research directions with the goal of realizing the promise of racial socialization as a resilience factor in African American and ethnic minority youth mental health.
A Dialogue on the Role of Computational Modeling in Developmental Science
Authors: Simmering Vanessa R. , Triesch Jochen , Deák Gedeon O. , Spencer John P.
Published: July 2010

Abstract—All sciences use models of some variety to understand complex phenomena. In developmental science, however, modeling is mostly limited to linear, algebraic descriptions of behavioral data. Some researchers have suggested that complex mathematical models of developmental phenomena are a viable (even necessary) tool that provide fertile ground for developing and testing theory as well as for generating new hypotheses and predictions. This article explores the concerns, attitudes, and historical trends that underlie the tension between two cultures: one in which computational simulations of behavior are an important complement to observation and experimentation and another that emphasizes evidence from behavioral experiments and linear models enhanced by verbal descriptions. This tension is explored as a dialogue among three characters: Ed (Experimental Developmentalist), Mira (Modeling Inclusive Research Advocate), and Phil (Philosopher of Science).
Performance of OCT segmentation procedures to assess morphology and extension in geographic atrophy
Authors: Schütze Christopher , Ahlers Christian , Sacu Stefan , Mylonas Georgios , Sayegh Ramzi , Golbaz Isabelle , Matt Gerlinde , Stock Géraldine , Schmidt‐Erfurth Ursula
Published: July 2010

Purpose:  Investigating segmentation procedures and morphological findings in time domain (TD) and current spectral domain (SD) optical coherence tomography (OCT) devices in patients with geographic atrophy (GA).

Methods:  Fifty eyes of 46 patients with GA secondary to AMD and 15 control eyes were examined in this prospective noninterventional comparative case series. All patients underwent Stratus (model 3000), Cirrus (Carl Zeiss Meditec), Spectralis (Spectralis HRA+OCT; Heidelberg Engineering) and 3D‐OCT‐1000 (Topcon). Automated segmentation analyses were compared. An overlay of scanning laser ophthalmoscope (SLO) and three‐dimensional retinal thickness (RT) maps were used to investigate whether areas of retinal thinning correspond to areas of retinal pigment epithelium (RPE) atrophy.

Results:  Geographic atrophy areas identified in SLO scans were significantly larger than areas of retinal thinning in RT maps. No convincing topographic correlation could be found between areas of retinal thinning and actual GA size as identified in SLO and fundus photography. Spectralis OCT showed significantly more mild and severe segmentation errors than 3D and Cirrus OCT.

Conclusion:  This study showed substantial limitations in identifying zones of GA reliably when using automatic segmentation procedures in current SD‐OCT devices. This limitation should be addressed to visualize and document RPE loss realistically in a frequent disease like GA.
Combination therapy in diabetic macular oedema and retinal vein occlusion – past and present
Authors: Koss Michael J. , Naser Helal , Sener Aysun , Ackermann Hanns , Al‐Sarireh Fawaz , Singh Pankaj , Koch Frank H.
Published: July 2010

This paper summarizes the recent evidence for combined therapies in the intravitreal medical treatment of diabetic macular oedema or macular oedema, secondary to retinal vein occlusion. Since the introduction of anti‐inflammatory or anti‐VEGF drugs combined with or used alternatively to laser, visual acuity can be stabilized or improved in a significant number of patients. However, there is an ongoing debate regarding the safety, efficiency and economic concerns related to these intravitreal monotherapies because they warrant frequent repetition to maintain the clinical effect. In the literature, the combination of photolasercoagulation, intravitreal steroids or VEGF‐inhibitors, or both, shows early compelling evidence that some patients may benefit from less retreatment compared to monotherapy. To provide a conceptual and perspective approach for a first‐line combined therapy, this paper also summarizes own results of pilot interventional case series of a 1.5 cc core pars plana vitrectomy and intravitreal substitution with balanced salt solution (BSS), 1.25 mg bevacizumab and 8 mg triamcinolone.
Management of hepatocellular carcinoma: Report of Consensus Meeting in the 45th Annual Meeting of the Japan Society of Hepatology (2009)
Authors: Arii Shigeki , Sata Michio , Sakamoto Michiie , Shimada Mitsuo , Kumada Takashi , Shiina Shuichiro , Yamashita Tatsuya , Kokudo Norihiro , Tanaka Masatoshi , Takayama Tadatoshi , Kudo Masatoshi
Published: July 2010

Hepatocellular carcinoma (HCC) is responsible for approximately 600 000–700 000 deaths worldwide. It is highly prevalent in the Asia–Pacific region and Africa, and is increasing in Western countries. The evidence‐based guideline for HCC in Japan was published in 2005 and revised in 2009. Apart from this guideline, a consensus‐based practice manual proposed by the HCC expert panel of the Japan Society of Hepatology (JSH), which reflects widely accepted daily practice in Japan, was published in 2007. At the occasion of the 45th Annual meeting of the JSH in Kobe 4–5 June 2009, a consensus meeting of HCC was held. Consensus statements were createdbased on 67% agreement of 200 expert members.This article describes the up‐to‐date consensus statements which largely reflect the real world HCC practice in Japan. We believe readers of this article will gain the newest knowledge and deep insight on the management of HCC proposed by consensus of the HCC expert members of JSH.
Response Evaluation Criteria in Cancer of the Liver (RECICL) proposed by the Liver Cancer Study Group of Japan (2009 Revised Version)
Authors: Kudo Masatoshi , Kubo Shouji , Takayasu Kenichi , Sakamoto Michiie , Tanaka Masatoshi , Ikai Iwao , Furuse Junji , Nakamura Kenji , Makuuchi Masatoshi ,   for The Liver Cancer Study Group of Japan (Committee for Response Evaluation Criteria in Cancer of the Liver, Liver Cancer Study Group of Japan)
Published: July 2010

The World Health Organization (WHO) criteria and Response Evaluation Criteria in Solid Tumors (RECIST) are inappropriate to assess the direct effects of treatment on the hepatocellular carcinoma (HCC) by locoreginal therapies such as radiofrequency ablation (RFA) and transcatheter arterial chemoembolization (TACE). Therefore, establishment of response evaluation criteria solely devoted for HCC is needed urgently in the clinical practice as well as in the clinical trials of HCC treatment, such as molecular targeted therapies, which cause necrosis of the tumor. Response Evaluation Criteria in Cancer of the Liver (RECICL) was revised in 2009 by Liver Cancer Study Group of Japan based on the 2004 version of RECICL, which was commonly used in Japan. Major revised points of the RECICL 2009 is to provide TE4a (Complete response with enough ablative margin) and TE4b (complete response without enough ablative margin) for local ablation therapy. Second revised point is that setting the timing at which the overall treatment effects are assessed. Third point is that emergence of new lesion in the liver is regarded as progressive disease, different from 2004 version. Finally, 3 tumor markers including alpha‐fetoprotein (AFP) and AFP‐L3 and des‐gamma‐carboxy protein (DCP) were also added for the overall treatment response. We hope this new treatment response criteria, RECICL, proposed by Liver Cancer Study Group of Japan will benefit the HCC treatment response evaluation in the setting of the daily clinical practice and clinical trials as well not only in Japan, but also internationally.
Application of the Kusuoka approximation with a tree-based branching algorithm to the pricing of interest-rate derivatives under the HJM model
Authors: Ninomiya Mariko
Published: July 2010

This paper demonstrates the application of a new higher-order weak approximation, called the Kusuoka approximation, with discrete random variables to non-commutative multi-factor models. Our experiments show that using the Heath–Jarrow–Morton model to price interest-rate derivatives can be practically feasible if the Kusuoka approximation is used along with the tree-based branching algorithm.
Piezoelectric Damping of Resistively Shunted Beams and Optimal Parameters for Maximum Damping
Authors: Liao Yabin , Sodano Henry A.
Published: July 2010

This paper studies the piezoelectric damping of resistively shunted beams induced by the conversion of the vibration energy into electrical energy that is dissipated in the resistor through Joule heating. Significant contributions have been made in the modeling and development of the resistive shunt damping technique; however, many approaches involve complex models that require the use of numerical methods to determine system parameters and predict damping. This paper develops a closed-form solution for the optimal parameter of a resistive shunt damping system. The model is validated through experimental testing and provides a simple yet accurate method to predict the induced damping in a smart structure.
Theoretical Study on Transient Hot-Strip Method by Numerical Analysis
Authors: Wei Gaosheng , Du Xiaoze , Zhang Xinxin , Yu Fan
Published: July 2010

This paper presented the effects of finite dimensions of the sample and nonzero heat capacity of the strip on thermal conductivity determination with the transient hot-strip method. Through the numerical analysis of the temperature field within the system composed of the samples and the strip, the temperature transients at the strip surface were obtained to calculate the thermal conductivities of materials, which were compared with the exact values. The effect of heat losses out of the external surfaces of the sample and the heat capacity of the strip on thermal conductivity determination were then analyzed comprehensively. It is shown that the sample finite dimensions have a great effect on thermal conductivity determination, especially on the materials with relatively higher thermal diffusivities, and the measured thermal conductivity is always lower than the exact value due to the lower convective heat transfer coefficient out of the external surfaces of the sample. The measurement error is estimated to be less than 2.1% for the material with thermal diffusivity less than 4.0×10−6 m2/s with the sample dimensions of 120×60 mm2(width×thickness) and the fitting time interval of 20–300 s. The nonzero heat capacity of the strip has a great effect on thermal conductivity determinations of the materials with relatively lower thermal diffusivities. The measurement error is estimated to be less than 5% for the material with thermal diffusivity larger than 0.8×10−7 m2/s with Cr20Ni80 alloy as the strip.
Numerical Investigation of Local Entropy Generation for Laminar Flow in Rotating-Disk Systems
Authors: Shanbghazani Mohammad , Heidarpoor Vahid , Rosen Marc A. , Mirzaee Iraj
Published: July 2010

The entropy generation is investigated numerically in axisymmetric, steady-state, and incompressible laminar flow in a rotating single free disk. The finite-volume method is used for solving the momentum and energy equations needed for the determination of the entropy generation due to heat transfer and fluid friction. The numerical model is validated by comparing it to previously reported analytical and experimental data for momentum and energy. Results are presented in terms of velocity distribution, temperature, local entropy generation rate, Bejan number, and irreversibility ratio distribution for various rotational Reynolds number and physical cases, using dimensionless parameters. It is demonstrated that increasing rotational Reynolds number increases the local entropy generation rate and irreversibility rate, and that the irreversibility is mainly due to heat transfer while the irreversibility associated with fluid friction is minor.
Gravity Scaling Parameter for Pool Boiling Heat Transfer
Authors: Raj Rishi , Kim Jungho , McQuillen John
Published: July 2010

Although the effects of microgravity, earth gravity, and hypergravity (>1.5 g) on pool boiling heat flux have been studied previously, pool boiling heat flux data over a continuous range of gravity levels (0–1.7 g) was unavailable until recently. The current work uses the results of a variable gravity, subcooled pool boiling experiment to develop a gravity scaling parameter for n-perfluorohexane/FC-72 in the buoyancy-dominated boiling regime (Lh/Lc>2.1). The heat flux prediction was then validated using heat flux data at different subcoolings and dissolved gas concentrations. The scaling parameter can be used as a tool to predict boiling heat flux at any gravity level in the buoyancy dominated regime if the data under similar experimental conditions are available at any other gravity level.
Investigation on Train Derailment Using a New Criterion
Authors: Durali Mohammad , Jalili Mohammad Mahdi
Published: July 2010

A new criterion for prediction of train derailment is presented in this paper. A 2 DOF wheel-set model is used to identify the main dynamic parameters that affect wheel-set derailment. Using these parameters and conventional definition of derailment coefficient, a new criterion for prediction of wheelset derailment is introduced. The proposed criterion, in addition to providing the required precision in prediction of wheelset derailment, it requires measurements which are easy to perform. To evaluate the capability of the new criterion in prediction of derailment, a full wagon model with 48 DOF was used. The wagon model is a 3-D, non-linear model of a train passenger car. The model includes non-linear elements for primary and secondary suspension systems. Friction and slack between elements, the center pivot with kinematics constraints, forces between pads, and bolster are also included in this model. The motion of the wagon on curved tracks is simulated for different travel speeds. Derailment coefficient and a new derailment criterion are used to investigate possibility of wheelset derailment in each case. The study shows that the new criterion can very well predict wheelset derailment and can duplicate the predictions by conventional derailment coefficient (Y / Q).
The Maintenance and Handling of Constraints in Machine Design
Authors: Matthews Jason , Ding Lian , Feldman Jonathan , Mullineux Glen
Published: July 2010

The engineering design process can be considered to be constraint oriented. It involves the identification, negotiation and resolution of an evolving set of constraints. The nature of engineering design is that such problems are rarely as simple as satisfying a single objective with all the design variation continuous and unbounded. Previous research has shown that as the design evolves, the designer can miss or overlook some of these constraints. To overcome this, the paper presents a supportive approach which allows the designer to annotate the initial CAD drawn models with the design constraints. These constraints are then maintained with the model as it evolves, this presents the opportunity to refine the constraints when the design activity requires. The approach has been created to support manufacturing machinery design and is demonstrated with an industrial case study.
Optimum Locations of Pin Supports to Minimize Deflection of a Thin Plate Acted Upon by Its Own Weight
Authors: Belegundu Ashok D.
Published: July 2010

The paper discusses solutions to the problem of optimally supporting a thin plate, acted upon by its self weight, with a discrete number of supports. Such problems occur, for example, in supporting ceiling tiles with fasteners. The goal is to minimize deflection which is visually unappealing. Minimizing deflection is especially important as the initial deflection increases with time due to creep. Square and rectangular plates are considered. The approach taken here is based on combining a bending plate finite element code with an optimizer. Results are presented for square and rectangular plates on a (three) discrete supports. A penalty function is used to ensure that supports are not collinear.
Experience With Developing a High-Productivity Test Framework for Scalable Embedded and Mechatronic Systems
Authors: Masticola Stephen P. , Subramanyan Rajesh
Published: July 2010

We describe the software core of a generic system test framework, named TF, for engineering verification of embedded and mechatronic systems. TF originated as an automated system test framework for the Siemens FireFinder XLS fire-safety system, but can be easily customized to place other systems under test. As a scalable and safety-critical system under rigorous certification constraints, XLS placed some very stringent requirements on the test harness. We performed a thorough evaluation of the available options for test executives, selecting the best one for our purposes. We then built TF on that test executive. TF enables high levels of productivity for both test developers and framework maintainers. TF also allows simulators to be substituted for physical hardware, without modifying the test scripts or underlying infrastructure. This feature is vitally important in scalability testing.
Nonlinear Vibrations and Stability of Shells Conveying Water Flow
Authors: Amabili Marco , Karagiozis Kostas , Pai¨doussis Michael P.
Published: July 2010

Shells containing flowing fluids are widely used in engineering applications, and they are subject to manifold excitations of different kinds, including flow excitations. The response of a shell conveying fluid to harmonic excitation, in the spectral neighbourhood of one of the lowest natural frequencies, is investigated for different flow velocities. The theoretical model has been developed using the Donnell theory retaining in-plane inertia. Linear potential flow theory is applied to describe the fluid-structure interaction, and the steady viscous effects are added to take into account flow viscosity. For different amplitudes and frequencies of the excitation and for different flow velocities, the following are investigated numerically: (i) periodic response of the system; (ii) unsteady and stochastic motion; (iii) loss of stability by jumps to bifurcated branches. The effect of the flow velocity on the nonlinear periodic response of the system has also been investigated. Bifurcation diagrams and Lyapunov exponents have been used to study the unsteady and stochastic dynamics of the system.
Strategies for Model Simplification and Data Reduction in Holographic Virtual Prototyping and Product Visualization Through Application Dependent Model Pre-Processing
Authors: Opiyo Eliab Z. , Horva´th Imre , Rusa´k Zolta´n
Published: July 2010

Three-dimensional (3D) displays are increasingly becoming common output devices for design support systems. They are widely used in applications such as virtual prototyping e.g. for visualization of product data and for concepts demonstration. Holographic displays are among the visualization devices that are capable of generating suitable 3D virtual models for these kinds of applications. However, these displays typically require powerful computers for processing and rendering large amount of volumetric data. Large amount of data in holographic displays and in volumetric displays in general often causes rendering delay, i.e. slow response to users’ actions and slow interaction speed. These problems, along with the problem of insufficient display resolution, have historically prevented 3D volumetric visualization technologies like holographic displays from becoming the mainstream product visualization means. In general terms, visualization of volumetric data requires sophisticated and efficient rendering methods that take the amount of data into account. In this paper, we introduce and discuss rigorous strategies for model simplification and data reduction in holographic display based virtual prototyping processes. Data reduction is achieved through model simplification; which involves identification of visualization demands for the application at hand and tailoring the model to meet these demands. We first briefly review the methods traditionally used in reducing computing resource requirements and then we propose strategies for lowering the amount of data in holographic virtual prototyping while keeping the displayed virtual model relevant to the visualization demands at hand. We also demonstrate by using practical examples the significance of the proposed strategies and how they can be used in practical settings. The proposed approach is configurable and scalable. It has been demonstrated in this work that its underlying algorithms can reduce computation burden in holographic displays and instigate swift computing by letting the display process information tailored specifically for particular visualization demands.
On-Board Aircraft Engine Bearing Prognostics: Enveloping or FFT Analysis?
Authors: Qiu Hai , Luo Huageng , Eklund Neil
Published: July 2010

Roller bearing prognosis requires the detection of a bearing defect signature in the earliest possible stage in order to avoid a minor or catastrophic mechanical failure. Defects can occur in any of the bearing parts, inner and outer race, cage and rolling elements. It is possible to identify the defective component of the bearing based on the specific vibration frequencies that are excited. However, the pattern of vibration spectrum changes as the bearing deteriorates through different stages. Depending on which failure stage the bearing is in, different techniques are required to find fault signatures in different frequency ranges. Techniques such as enveloping analysis that works in the high frequency region require higher data sampling rates and therefore more expensive data acquisition hardware than techniques conducted in low frequency region. This paper compares two popular rolling element bearing diagnostics techniques — spectrum analysis in the bearing characteristic frequency range and enveloping analysis in the high frequency range — using aircraft engine test rig data. The techniques are compared both in terms of the time of detection and data sampling requirement; this analysis provides guidance for technology adoption in future field deployment. Results demonstrate that enveloping analysis is able to detect bearing defects much earlier than the spectrum analysis, but it requires a higher data sampling rate. The bearing defect characteristic frequency is detectable in low frequency spectrum only in the late stage of the failure and it is contaminated by other harmonics such as shaft unbalance. From a practical perspective, the final choice of the technology adopted for deployment should be based on an analysis of hardware requirements and tolerance of detection latency.
A Mechatronic Active Force Control System for Real Time Test Loading of an Aircraft Landing Gear
Authors: Jacazio Giovanni , Balossini Gualtiero
Published: July 2010

This paper describes an electronically controlled active force control system that was recently developed to provide real time loading for the tests of a landing gear. As the landing gear moves during the test, a force is generated on the landing gear in order to ensure that its dynamics is identical to that that would occur during its operation in an actual flight. Since landing gear deployment and retraction can occur at different environmental and flight conditions, the load profile that must be developed by the force control system depends on the simulated flight condition and is determined by an appropriate landing gear model. To attain accurate force control, a system was setup comprised of a servovalve controlled hydraulic actuator, force and position sensors, and a high rate digital controller implementing a complex adaptive control law. An excellent accuracy of the load control was eventually achieved for all load profiles occurring on the landing gear.
The Extended Melnikov Method for Non-Autonomous Higher Dimensional Nonlinear Systems and Multi-Pulse Chaotic Dynamics of Laminated Composite Piezoelectric Plate
Authors: Zhang Wei , Zhang Jun-Hua
Published: July 2010

The global bifurcations and multi-pulse chaotic dynamics of a simply supported laminated composite piezoelectric rectangular thin plate under combined parametric and transverse excitations are investigated in this paper for the first time. The formulas of the laminated composite piezoelectric rectangular plate are derived by using the von Karman-type equation, the Reddy’s third-order shear deformation plate theory and the Galerkin’s approach. The extended Melnikov method is improved to enable us to analyze directly the non-autonomous nonlinear dynamical system, which is applied to the non-autonomous governing equations of motion for the laminated composite piezoelectric rectangular thin plate. The results obtained here indicate that the multi-pulse chaotic motions can occur in the laminated composite piezoelectric rectangular thin plate. Numerical simulation is also employed to find the multi-pulse chaotic motions of the laminated composite piezoelectric rectangular thin plate.
Periodic and Chaotic Oscillations of Composite Laminated Thin Plate With Third-Order Shear Deformation
Authors: Zhang W. , Guo X. Y.
Published: July 2010

An analysis on the nonlinear oscillations and chaotic dynamics is presented for a simply-supported symmetric cross-ply composite laminated rectangular thin plate with parametric and forcing excitations. Based on the Reddy’s third-order shear deformation plate theory and the von Karman type equation, the nonlinear governing partial differential equations of motion for the composite laminated rectangular thin plate are derived by using the Hamilton’s principle. The Galerkin method is utilized to discretize the governing partial differential equations of motion to a three-degree-of-freedom nonlinear system including the cubic nonlinear terms. The case of 1:3:3 internal resonance and fundamental parametric resonance, 1/3 subharmonic resonance is considered. The method of multiple scales is employed to obtain the averaged equation. The stability analysis is given for the steady-state solutions of the averaged equation. The Numerical method is used to investigate the periodic and chaotic motions of the composite laminated rectangular thin plate. The results of numerical simulation demonstrate that there exist different kinds of periodic and chaotic motions of the composite laminated rectangular thin plate under certain conditions.
Tracking Control of Uncertain Nonholonomic Mobile Robots: Smooth Switching Approach
Authors: Huang Jeng-Tze , Chang Chih-Hao
Published: July 2010

Backstepping based adaptive tracking control of non-holonomic mobile robots in the presence of both kinematic and dynamic parametric uncertainty is presented. The major challenge is the possible singularity phenomenon due to the approach of zero of the estimated input vector field entering the denominator of the control input, a common drawback of adaptive linearization-based schemes. A hybrid control approach, which switches between an adaptive and a robust control schemes, is developed for solving such a problem. It retains the advantage of an adaptive control approach to a greatest extent while avoiding the possible blowup of the torque inputs simultaneously. A case study on a specific Type (2; 0) mobile robot is provided in the final to verify the usefulness of the proposed design.
Robust Control of Coordinated Motion for Free-Floating Space Flexible Manipulator by Singular Perturbation Approach
Authors: Li Chen , Zhaobin Hong
Published: July 2010

The robust control of coordinated motion and active vibration control for free-floating space flexible manipulator with an attitude-controlled base are studied. The dynamic equations of the system are developed by using the Lagrangian assumed modes methods, it is verified that the dynamic equation can be linearly dependent on a group of inertial parameters. Based on the results and under the assumption of two-time scale, singular perturbation model of the space flexible manipulator system is obtained. The fast subsystem controller will damp out the vibration of the flexible link using optimal Linear Quadratic Regulator (LQR) method. The slow subsystem robust controller dominates the trajectory tracking of coordinated motion. In particular, the control scheme doesn’t require measuring the position, velocity nor acceleration of the base. The numerical simulation is carried out, which confirms the controller proposed is feasible and effective.
Adaptive Neural Network Compensating Control for Coordinated Motion of Space-Based Robot System With Uncertain Parameters and External Disturbances
Authors: Zhiyong Chen , Li Chen
Published: July 2010

The control problem of space-based robot system with uncertain parameters and external disturbances is considered. With Lagrangian formulation and augmentation approach, the dynamic equations of space-based robot system in workspace are derived. Based on the results, an adaptive neural network compensating control scheme for coordinated motion between the base’s attitude and end-effector of space-based robot system is developed. It is based on the inertia-related method, and incorporates a neural network controller to compensate the uncertainties. The closed-loop system stability with the neural network adapted on-line is discussed in detail through the Lyapunov stability approach. Comparing with many adaptive and robust control schemes, the controller proposed does not require one to determine the regression matrix for space robot system and then avoids tedious computations. Numerical simulations are provided to show the effectiveness of the approach.
On Stability of N-Dimensional Dynamical Systems
Authors: Luo Albert C. J.
Published: July 2010

This paper presents a theory of the stability of equilibrium in dynamical systems. The measuring function is introduced through a relative distance function. The kth -order, G – functions at the equi-measuring function surface and the increment of the equi-measuring function are introduced. Based on the kth -order, G – functions, a theory for the stability of dynamical system is presented, including the definitions and theorems.
Analytical Calculation of Cutter/Workpiece Engagements for Helical Hole Milling
Authors: Wang Jue , Yip-Hoi Derek
Published: July 2010

Helical milling is a 3-axis machining operation where a cutting tool is feed along a helix. This operation is used in ramp-in and ramp-out moves when the cutting tool first engages the workpiece, for contouring and for hole machining. It is increasingly finding application as a means for roughing large amounts of material during high speed machining. Simulating the helical milling process requires Cutter/Workpiece Engagement (CWE) geometry in order to predict cutting forces. The calculation of these engagements is challenging due to the complicated and changing intersection geometry that occurs between the cutter and the in-process workpiece. For hole milling an additional complication comes from self-intersections that occur with the tool swept volume. This makes the generation of the instantaneous in-process workpiece needed for finding the CWE difficult. In this paper we present an analytical approach for finding the engagement geometry that utilizes the intersection curves between a cylinder representing a flat end mill and the helicoidal surface generated by the bottom of the tool as it feeds downwards along the helix. This technique can be integrated into a solid modeler based approach for machining simulation. It has the advantage of not require instantaneous updates of the workpiece as is typically the case in finding CWEs.
Modal Analysis With Smooth Karhunen-Loe`ve Decomposition
Authors: Bellizzi S. , Sampaio Rubens
Published: July 2010

In this paper, the Smooth Orthogonal Decomposition is formulated in term of a Smooth Karhunen-Loe`ve Decomposition (SKLD) to analyze random fields. The SKLD is obtained solving a generalized eigenproblem defined from the covariance matrix of the random field and the covariance matrix of the associated time derivative random field. The main properties of the SKLD are described and compared to the classical Karhunen-Loe`ve decomposition. The SKLD is then applied to the responses of randomly excited vibrating systems with a view to performing modal analysis. The associated SKLD characteristics are interpreted in case of linear vibrating systems subjected to white noise excitation in terms of normal modes. Discrete and continuous mechanical systems are considered in this study.
Accurate Geometric Description of Spirals in Railroad Vehicle Dynamic Simulations
Authors: Marquis Brian , Zaazaa Khaled E. , Sinokrot Tariq Z. , Shabana Ahmed A.
Published: July 2010

The objective of this study is to examine the geometric description of the spiral sections of railway track systems in order to correctly define the relationship between the geometry of the right and left rails. The geometry of the space curves that define the rails are expressed in terms of the geometry of the space curve that defines the track center curve. Industry inputs such as the horizontal curvature, grade, and super-elevation are used to define the track centerline space curve in terms of Euler angles. The analysis presented in this study shows that, in the general case of a spiral, the profile frames of the right and left rails that have zero yaw angle with respect to the track frame have different orientations. As a consequence, the longitudinal tangential creep forces acting on the right and left wheels, in the case of zero yaw angle, are not in the same direction. Nonetheless, the orientation difference between the profile frames of the right and left rails can be defined in terms of a single pitch angle. In the case of small bank angle that defines the super-elevation of the track, one can show that this angle directly contributes to the track elevation. The results obtained in this study also show that the right and left rail longitudinal tangents can be parallel only in the case of a constant horizontal curvature. Since the spiral is used to connect track segments with different curvatures, the horizontal curvature can not be assumed constant, and as a consequence, the right and left rail longitudinal tangents can not be considered parallel in the spiral region. Numerical examples that demonstrate the effect of the errors that result from the assumption that the right and left rail in the spiral sections have the same geometry are presented. The numerical results obtained show that these errors can have a significant effect on the quality of the predicted creep contact forces.