bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiological sinus lift: a new minimally invasive CT‐guided procedure for maxillary sinus floor elevation in implant dentistry
Authors: Matern Jean‐François , Keller Pierre , Carvalho Jean , Dillenseger Jean‐Philippe , Veillon Francis , Bridonneau Thomas
Published: January 2015

Purpose

Implant therapy has become an excellent treatment modality as its inception into the modern era of dentistry. However, when patients present with advanced atrophy of the maxillary alveolar ridge, the procedure of choice to restore the anatomic bone deficiency is surgical maxillary sinus floor elevation or sinus lift. The purpose of this study was to describe the CT guided sinus lift technique and to illustrate the minimally invasive aspect of this new radiological procedure called radiological sinus lift.

Material and methods

For this prospective study, 17 cadaver heads which met our inclusion criteria (edentulous posterior maxillary sector and bone height less than 5 mm) were analyzed using cone beam computed tomography (CBCT) and orthopantomography (OPT). CT and sinus endoscopy was used to guide each step in the procedure. The radiological sinus lift technique consists of the following four stages: Approach. A 14.5 G OstyCut needle was inserted mesial to the canine eminence, and manual drilling was performed parallel to the sinus floor. Osteotomy. An inner obturator with a blunt tip was introduced to compress bone, to push it in close proximity to the sinus membrane and finally to create an osseous window opening into the submucosal space. Lifting. The sinus lift was performed using hydrodissection with dilute iodinated contrast medium. Filling. The submucosal space was then filled with an injection of dilute collagen. Success of the radiological sinus lift procedure was defined by the presence of a dome shape visible within the maxillary alveolar recess. All cases were imaged postoperatively using OPT and maxillary CBCT.

Results

Twelve maxillary sinuses underwent the radiological sinus floor elevation procedure. A dome shape of the Schneiderian membrane was achieved in eight maxillary sinuses (66.7%). All failures (n = 4) were caused by mucosal perforation at the time of maxillary sinus osteotomy. Mean height of membrane elevation was 12.0 mm, with a mean intervention time of 45 min.

Conclusion

This experimental study evaluates a new minimally radiological procedure for maxillary sinus floor elevation, which provides an interventional radiological alternative to the classical surgical lateral approach and achieves an equivalent success rate to that cited in the literature for the surgical approach, a low morbidity and a shorter operating time.
Stability of depressive symptoms over 3 months post‐partum
Authors: Abdollahi Fatemeh , Zarghami Mehran , Sazlina Shariff‐Ghazali , Lye Munn‐Sann
Published: January 2015

Aim

Prolonged depression during the post‐partum period is associated with maternal and infant mortality and morbidity. Less attention has been given to factors that predict the persistence of depression beyond the first 3 months post‐partum.

Methods

From a longitudinal cohort of 2279 women who attended Mazandaran's primary health centres in 2009, 478 women with an Edinburgh Postnatal Depression Scale (EPDS) score of 12 or greater in the third trimester of pregnancy were recruited. Persistently depressed women (depressed at all three occasions: during pregnancy, and at 2 and 12 weeks post‐partum) were compared with those without depression to determine demographic, cultural, obstetric and biopsychosocial predictors for persistence of depression. Data were analysed using chi‐square test, t‐test and logistic regression models.

Results

The stability of depression was found in 193 (46.2 %) of 418 depressed cases who were followed up over the study period. Of those mothers who scored more than the threshold of 12 during the third trimester of pregnancy, 277 (66.3%) and 221 (52.9%) had high EPDS at 2 and 12 weeks post‐partum. Psychological distress (based upon the General Health Questionnaire), low maternal parental self‐efficacy (based upon the Parental Expectation Survey) and perceived social isolation (based upon the Network Orientation Scale) were independent predictors of persistent depression.

Conclusion

Fewer depressed mothers in this study were found to recover during the first 3 months after giving birth. Psychosocial factors predicted sustained depression from pregnancy to 3 months post‐partum. The findings highlight the significance of support in enhancing maternal mental health.
Mindfulness‐based cognitive therapy for youth with anxiety disorders at risk for bipolar disorder: a pilot trial
Authors: Cotton Sian , Luberto Christina M. , Sears Richard W. , Strawn Jeffrey R. , Stahl Lauren , Wasson Rachel S. , Blom Thomas J. , Delbello Melissa P.
Published: January 2015

Aim

Children and adolescents with bipolar parents have an elevated risk for anxiety disorders. However, antidepressant medications commonly used to treat symptoms of anxiety may accelerate the onset of mania in these already at‐risk youth. Therefore, studies evaluating innovative non‐pharmacologic treatments for anxiety in this population are urgently needed.

Methods

Subjects participated in 12 weekly sessions of mindfulness‐based cognitive therapy for children (MBCT‐C), a manualized group psychotherapeutic intervention utilizing cognitive behavioural principles and mindfulness exercises to increase regulation of attention and non‐judgmental acceptance of present moment thoughts, emotions and experiences. Independent raters administered symptoms rating scales prior to each treatment session. Spearman correlations and paired‐samples signed rank tests were used to examine outcomes. After‐intervention surveys and session transcripts were reviewed to assess feasibility and acceptability of the intervention.

Results

Participants included 10 youth (meanage = 13.2; 80% girls; 40% biracial) with generalized, social and/or separation anxiety disorders, and a parent with bipolar disorder. Clinician‐rated anxiety was significantly reduced after intervention (meanbefore = 11.1; meanafter = 4.3; P < 0.01), as well as youth‐rated trait anxiety (P = 0.03). Parent‐rated emotion regulation significantly increased from before to after intervention (P = 0.05). Increases in mindfulness were associated with decreases in anxiety (P = 0.03). Finally, children and parents/guardians reported high levels of feasibility, acceptability and usefulness of the intervention.

Conclusion

Findings support the feasibility, acceptability and preliminary efficacy of MBCT‐C for treating anxiety in youth at risk for bipolar disorder. Future controlled and larger studies are needed to confirm these preliminary findings.
Duration of active psychosis and first‐episode psychosis negative symptoms
Authors: Lyne John , Joober Ridha , Schmitz Norbert , Lepage Martin , Malla Ashok
Published: January 2015

Aim

Duration of untreated psychosis (DUP) has been associated with negative symptoms in several studies; however, longitudinal findings have been inconsistent. No previous study has accounted for active psychosis after presentation, although this could impact on outcomes in a manner similar to DUP.

Methods

We measured Scale for the Assessment of Positive Symptoms at frequent intervals during the 12 months after initial presentation to determine the active psychosis duration for 230 individuals with first‐episode psychosis. This duration was added to DUP prior to presentation to create a new variable, duration of active psychosis (DAP). Negative symptoms were divided into expressivity and motivation/pleasure domains as measured by Scale for the Assessment of Negative Symptoms (SANS). The relationship of DUP and DAP with negative symptoms at 24‐month follow up was determined and confounders controlled for using regression analysis.

Results

When DUP and DAP were compared as binary variables with long and short groups, 25.2% of individuals had differing category membership. DAP had a significant uncorrected association with both expressivity domain and motivation/pleasure domains at 24 months; however, relationship with DUP was not significant. DAP remained a significant predictor of 24‐month expressivity domain after controlling for potential confounders.

Conclusions

Active psychosis after presentation is substantial, which is a limitation of DUP studies if active psychosis is considered as the key factor within DUP. DAP is a better predictor of negative symptoms than DUP at 2‐year follow up, which suggests this concept requires further research.
Intimate Partner Relationship Distress in the DSM‐5
Authors: Foran Heather M. , Whisman Mark A. , Beach Steven R. H.
Published: January 2015

Over the past 40 years, a large body of literature has documented intimate partner relationship distress as a primary reason for seeking mental health services as well as an integral factor in the prognosis and treatment of a range of mental and physical health conditions. In recognition of its relevance to clinical care, the description of intimate partner relationship distress has been expanded in the DSM‐5. Nonetheless, this is irrelevant if the DSM‐5 code for intimate partner relationship distress is not reliably used in clinical practice and research settings. Thus, with the goal of dissemination in mind, the purpose of this paper was to provide clinicians and researchers with specific guidelines on how to reliably assess intimate partner relationship distress and how this information can be used to inform treatment planning. In addition to the implications for direct clinical care, we discuss the importance of reliable assessment and documentation of intimate partner relationship distress for future progress in epidemiology, etiology, and public health research.
Short‐Term Performance of U.S.‐Bound Chinese IPOs
Authors: Haggard K. Stephen , Walkup Brian R. , Xi Yaoyi
Published: January 2015

Firms from emerging markets, including China, increasingly seek to raise capital outside of their home markets. We examine the short‐term performance of U.S.‐bound Chinese initial public offerings (IPOs) and find that these IPOs have significantly lower underpricing than a matched sample of U.S. counterparts. We also find that the magnitude of IPO underpricing for U.S.‐bound Chinese firms is positively related to revisions in offer price.
Influence of Prostate Stem Cell Antigen Gene Polymorphisms on Susceptibility to Helicobacter pylori‐associated Diseases: A Case‐control Study
Authors: Ichikawa Hitomi , Sugimoto Mitsushige , Uotani Takahiro , Sahara Shu , Yamade Mihoko , Iwaizumi Moriya , Yamada Takanori , Osawa Satoshi , Sugimoto Ken , Miyajima Hiroaki , Yamaoka Yoshio , Furuta Takahisa
Published: January 2015

Background

Patients with duodenal ulcer have a reduced risk of developing gastric cancer compared to those without. Recently, the prostate stem cell antigen (PSCA) rs2294008 C>T polymorphism was found to be associated with different pathogenesis of duodenal ulcer and gastric cancer developments. However, whether PSCA rs2294008 C>T polymorphism is associated with severity of gastric mucosal atrophy is unclear. We examined the influence of the PSCA rs2294008 C>T polymorphism on susceptibility to H. pylori‐related diseases and the relationships between PSCA polymorphism and gastric mucosal atrophy.

Methods

PSCA rs2294008 C>T polymorphism was assessed in H. pylori‐positive Japanese patients (n = 488) with noncardia gastric cancer (n = 193), gastric ulcer (n = 84), duodenal ulcer (n = 61), and atrophic gastritis (n = 150), as well as in H. pylori‐negatives (n = 266).

Results

Frequency of PSCA rs2294008 C/C genotype in duodenal ulcer was 36.1%, which was significantly higher than those with gastric cancer (12.4%), gastric ulcer (19.0%), gastritis (10.7%), and H. pylori‐negatives (19.5%) (p < .001). Compared with duodenal ulcer, having the T allele significantly increased the risk of gastric cancer (OR: 3.97, 95% CI: 2.02–7.80; p < .001), gastric ulcer (2.40, 1.13–5.10; p = .023), and gastritis (4.72, 2.26–9.86; p < .001). Mean pepsinogen (PG) I/PG II ratio in T allele carriers (2.17 ± 0.75) was significantly lower than that in C/C genotype (3.39 ± 1.27, p < .001).

Conclusions

The PSCA rs2294008 C>T polymorphism is associated with differing susceptibilities to H. pylori‐associated diseases. The PSCA rs2294008 C>T polymorphism may be acting through induction of gastric mucosal atrophy, finally leading to development of gastric ulcer and gastric cancer in PSCA rs2294008 T allele carriers, but not duodenal ulcer.
The Tennessee study: factors affecting treatment outcome and healing time following nonsurgical root canal treatment
Authors: Azim A. A. , Griggs J. A. , Huang G. T.‐J.
Published: January 2015

Aim

To determine factors that may influence treatment outcome and healing time following root canal treatment.

Methodology

Root filled and restored teeth by pre‐doctoral students were included in this study. Teeth/roots were followed‐up regularly, and treatment outcome was evaluated at every follow‐up appointment (healed, healing, uncertain or unsatisfactory). Host (age, immune condition, pulp/periapical diagnosis, tooth/root type, location and anatomy) and treatment factors (master apical file size, apical extension, voids and density of root filling) were recorded from patient dental records. Univariate, bivariate and multivariate analyses were performed to determine the impact of the factors on treatment outcomes and healing times.

Results

A total of 422 roots from 291 teeth met the inclusion criteria with a mean follow‐up period of 2 years. The preoperative pulp condition, procedural errors during treatment, apical extension and density of root fillings significantly affected the treatment outcome. The average time required for a periapical lesion to heal was 11.78 months. The healing time increased in patients with compromised healing, patients older than 40 years, roots with Weine type II root canal systems, root canal systems prepared to a master apical file size <35, and roots with overextended fillings (P < 0.1).

Conclusion

Multiple host and treatment factors affected the healing time and outcome of root canal treatment. Follow‐up protocols should consider these factors before concluding the treatment outcome: patient's age, immune condition, as well as roots with overextended fillings, root canal systems with smaller apical preparations (size <35) or roots with complex canal systems. Intervention may be recommended if the treatment quality was inadequate or if patients became symptomatic.
Does Immigration Undermine Public Support for Integration in the European Union?
Authors: Toshkov Dimiter , Kortenska Elitsa
Published: January 2015

It is well established that negative attitudes towards immigrants are strongly associated with lower public support for European integration. But the impact of actual immigration levels on immigration attitudes is still contested. As a result, the relationship between immigration levels and EU public support remains uncertain from a theoretical point of view. We offer an empirical study of the link between immigration from the new EU member states from Central and Eastern Europe (CEE) and EU support at the regional level in Spain, France, Ireland and The Netherlands. The results of the analyses suggest that in all four countries immigration from CEE had negative effects on support for European integration in the host societies. In short, immigration seems to undermine integration, although internal migration within the EU is necessary for the successful functioning of its economic union and the future of political integration.
Clinical and epidemiological features of Guillain‐Barré syndrome in the Western Balkans
Authors: Peric Stojan , Milosevic Vuk , Berisavac Ivana , Stojiljkovic Olivera , Beslac‐Bumbasirevic Ljiljana , Marjanovic Ivan , Djuric Vanja , Djordjevic Gordana , Rajic Sonja , Cvijanovic Milan , Babic Milica , Dominovic Aleksandra , Vujovic Balsa , Cukic Mirjana , Petrovic Milutin , Toncev Gordana , Komatina Nenad , Martic Vesna , Lavrnic Dragana
Published: January 2015

Abstract

The aim of this study was to define features of Guillain‐Barré syndrome in a large cohort of patients from three Western Balkans countries. Data from adult Guillain‐Barré syndrome (GBS) cases from 2009 to 2013 were retrospectively obtained from all tertiary health care centers. During the 5‐year period, 327 new cases of GBS were identified with a male to female ratio of 1.7 : 1. The most common GBS variants were demyelinating (65%) and axonal (12%). At nadir 45% of patients were chair‐bound, confined to bed, or required assisted ventilation, while 5% died. The crude incidence of GBS in Serbia and Montenegro was 0.93 per 100,000 population, and age‐adjusted incidence according to the world standard population was 0.86 per 100,000. Incidence was particularly high in 50‐ to 80‐year‐old men. Statistically significant seasonal variations of GBS were not observed. This study of patients with GBS in the Western Balkans allows us to prepare the health system better and to improve the management of patients. This study also opens opportunities for international collaboration and for taking part in the multinational studies on GBS.
A pilot study of proximal strength training in Charcot‐Marie‐Tooth disease
Authors: Ramdharry Gita M. , Pollard Alexander , Anderson Cheryl , Laurá Matilde , Murphy Sinead M. , Dudziec Magdalena , Dewar Elizabeth L. , Hutton Elspeth , Grant Robert , Reilly Mary M.
Published: January 2015

Gait analysis of people with Charcot‐Marie‐Tooth (CMT) disease revealed proximal adaptive gait strategies to compensate for foot drop. We previously demonstrated that hip flexor muscle fatigue can limit walking endurance. This pilot study used a single‐blinded cross over design to investigate the effect of a 16‐week home‐based programme of resistance training on hip flexor muscle strength. Measures of walking endurance, gait speed, exertion, fatigue, and general activity were also recorded. The exercise protocol was based on American College of Sports Medicine recommendations. A mixed effects model was used for analysis. Twenty‐six people finished the study, with average reported exercise participation of 93%. No negative effects of exercise were observed. Significant increase in hip flexor muscle strength was observed on the left, but not the right. No changes were observed in walking speed and endurance measures. This pilot study of home‐based resistance training showed a modest improvement in hip strength but only on one side. The lack of a more significant improvement and no improvement in walking measures suggests that this training protocol may not be optimal for people with CMT and that patients may need to stratified differently for training studies in CMT.
The influence of numbers on invasion success
Authors: Blackburn Tim M. , Lockwood Julie L. , Cassey Phillip
Published: January 2015

The process by which a species becomes a biological invader, at a location where it does not naturally occur, can be divided into a series of sequential stages (transport, introduction, establishment and spread). A species' success at passing through each of these stages depends, in a large part, on the number of individuals available to assist making each transition. Here, we review the evidence that numbers determine success at each stage of the invasion process and then discuss the likely mechanisms by which numbers affect success. We conclude that numbers of individuals affect transport and introduction by moderating the likelihood that abundant (and widespread) species are deliberately or accidentally translocated; affect establishment success by moderating the stochastic processes (demographic, environmental, genetic or Allee) to which small, introduced populations will be vulnerable; and affect invasive spread most likely because of persistent genetic effects determined by the numbers of individuals involved in the establishment phase. We finish by suggesting some further steps to advance our understanding of the influence of numbers on invasion success, particularly as they relate to the genetics of the process.
Primary metabolism plays a central role in moulding silicon‐inducible brown spot resistance in rice
Authors: Van Bockhaven Jonas , Steppe Kathy , Bauweraerts Ingvar , Kikuchi Shoshi , Asano Takayuki , Höfte Monica , De Vleesschauwer David
Published: January 2015

Over recent decades, a multitude of studies have shown the ability of silicon (Si) to protect various plants against a range of microbial pathogens exhibiting different lifestyles and infection strategies. Despite this relative wealth of knowledge, an understanding of the action mechanism of Si is still in its infancy, which hinders its widespread application for agricultural purposes. In an attempt to further elucidate the molecular underpinnings of Si‐induced disease resistance, we studied the transcriptome of control and Si‐treated rice plants infected with the necrotrophic brown spot fungus Cochliobolus miyabeanus. Analysis of brown spot‐infected control plants suggested that C. miyabeanus represses plant photosynthetic processes and nitrate reduction in order to trigger premature senescence and cause disease. In Si‐treated plants, however, these pathogen‐induced metabolic alterations are strongly impaired, suggesting that Si alleviates stress imposed by the pathogen. Interestingly, Si also significantly increased photorespiration rates in brown spot‐infected plants. Although photorespiration is often considered as a wasteful process, recent studies have indicated that this metabolic bypass also enhances resistance during abiotic stress and pathogen attack by protecting the plant's photosynthetic machinery. In view of these findings, our results favour a scenario in which Si enhances brown spot resistance by counteracting C. miyabeanus‐induced senescence and cell death via increased photorespiration. Moreover, our results shed light onto the mechanistic basis of Si‐induced disease control and support the view that, in addition to activating plant immune responses, Si can also reduce disease severity by interfering with pathogen virulence strategies.
The strategy does not matter: Effects of acceptance, reappraisal, and distraction on the course of anticipatory anxiety in social anxiety disorder
Authors: Helbig‐Lang Sylvia , Rusch Silke , Rief Winfried , Lincoln Tania M.
Published: January 2015

Objectives

Anticipatory anxiety is a core feature of social anxiety disorder (SAD); however, there is a paucity of data on effective strategies for dealing with this affective state. The present study examined the effects of reappraisal, acceptance, and distraction on the course of anticipatory anxiety.

Design

The study used an experimental design, randomly assigning participants to one of three strategy groups. Participants were instructed to employ these strategies during the anticipation of an impromptu speech.

Methods

Participants with SAD (n = 67) and healthy controls (n = 72) were compared with regard to their ability to adopt the prescribed strategies and with regard to the effects of strategy use on self‐reported and psychophysiological markers of arousal.

Results

SAD participants reported more problems in adopting the assigned strategies than controls, although the time spent with each strategy did not differ by group. In both groups, acceptance was rated as more difficult to adopt than reappraisal and distraction. Subjective ratings of anxiety decreased during the first 10 min of anticipation regardless of diagnostic group or strategy, but anxiety increased again immediately prior to the speech. Psychophysiological parameters were largely unaffected by group or strategy.

Conclusion

The results question whether there are differential benefits of different emotion regulation (ER) strategies in dealing with anticipatory anxiety. The observed rebound of anxiety prior to the social event calls into doubt the long‐term effectiveness of these strategies, at least during the regulation of anticipatory anxiety.

Practitioner points

Coping with anticipatory anxiety is an important issue in treating SAD.

Compared to healthy controls, individuals diagnosed with SAD experienced more problems in adopting prescribed ER strategies for dealing with anticipatory anxiety.

We found no differences between acceptance, reappraisal, and distraction, calling into question that one strategy should be generally recommended by clinicians.
IPRs and International Knowledge Flows: Evidence from Six Large Emerging Countries
Authors: Montobbio Fabio , Primi Annalisa , Sterzi Valerio
Published: January 2015

This paper studies international knowledge flows looking at: (i) patent citations that track codified knowledge and (ii) technological collaborations between inventors that gauge knowledge transmitted through face to face contacts. It uses a gravity model for 13 countries (Brazil, Russian Federation, India, China, South Africa, Mexico, the USA, the UK, Japan, Italy, Germany, France and Canada) using EPO data. In the case of tacit knowledge flows it shows that intellectual property rights (IPRs) reinforcement has no effect and that sharing a common legal origin and technological proximity are more important than geographical distance. In the case of codified knowledge flows IPRs reinforcement has a positive effect only when applicants’ citations are considered.
Gasification of Torrefied and Soft Wood Pellets in Air and CO2
Authors: Trehan K. , Molintas H. , Gupta A. K.
Published: January 2015

This paper examines the gasification of woody biomass pellets and torrefied wood pellets at different temperatures using air or CO2 as the gasifying agents. The woody biomass pellets were pyrolyzed and gasified in a controlled reactor facility that allowed for the determination of sample weight loss as a function of time from which the kinetics parameters were evaluated. The experimental facility provided full optical access that allowed for in-situ monitoring of the fate of the biomass pellets and the release of gas phase under prescribed high temperature condition. Pellet sample of known weight was placed in a wire mesh cage and then introduced instantly into the high temperature zone of the reactor at known temperature and surrounding gas composition as gasifying agent. The weight loss as function of time was examined for different gasification temperatures ranging from 600–950°C using air or CO2 as the gasifying agent. Significant differences in the weight loss were observed to reveal the fundamental pyro-gasification behavior between the wood and torrefied wood pellets. The results show enhanced gasification with air at low to moderate temperatures while at high temperatures the oxygen evolved from CO2 provided a role in oxidation. The calculated activated energy was lower for woody pellets than torrefied wood pellets and it was lower with air than CO2. These kinetic parameters help in modeling to design biomass gasifiers and combustors for increased conversion efficiency and performance using biomass or municipal solid waste pellets.
Smooth Friction Control Strategy for DM-Clutch Based Driveline Systems
Authors: Song Xubin , Liu Jason
Published: January 2015

Centrifugally operated friction clutches, named DM clutch in this paper, had been developed to couple an engine to an inputshaft of a mechanical transmission for commercial vehicles [1]. The DM clutch based AMT (automated mechanical transmission) has been in production from Eaton for more than a decade in the North American commercial vehicle market. Its working principle is to take advantage of the centrifugal force of sliding masses between two clutch plates to complete the transitions among unlock, slipping and lockup. DM clutch is reliable and durable, but not easy to modulate because of involvement of engine speed controls, nonlinear friction forces and variable vehicle loads. One challenging aspect is the occurrence of torsional vibrations during vehicle launches. In this paper, a friction based damping control strategy [2, 3] utilizing the frictional characteristics is shown to control the DM clutch to achieve smoother vehicle launch. The vehicle testing data shows its effectiveness of smoothening the vehicle launches with and without the loaded trailer under different operational conditions.
Sketching in Air: A Single Stroke Classification Framework
Authors: Babu Sree Shankar Satheesh , Jaiswal Prakhar , Esfahani Ehsan T. , Rai Rahul
Published: January 2015

We describe a trainable, hand drawn, single stroke 3D sketch–based classification system, using a motion detecting depth sense camera. Our system captures data from a user, who is free to sketch any desired shape in a 3D environment. The overall system is based on a set of previously defined and well developed classifiers, which are, the Rubine Classifier, $1 recognizer and the Image based classifier. The novelty of this paper comes from 1) the classification of sketches drawn in a 3D environment; 2) extending the pixel based image representation to a voxel–based scheme; and 3) combining the results from individual classifiers using a sensitivity matrix. To evaluate the performance of the system, user studies were performed. To validate the significance of results obtained from the user studies, we performed a t–test. Our system outperforms the individual classifiers and is able to achieve an average overall accuracy of 93+%.
Computational Geometric Solutions for Efficient Additive Manufacturing Process Planning
Authors: Verma Anoop , Rai Rahul
Published: January 2015

Additive manufacturing processes are capable of printing parts with any shape and complexity. The parts fabricated with additive manufacturing processes requires minimum human intervention. Process planning decisions play an important role in making sure the fabricated parts meets the desired specification, including the build time and cost. A quick and unified approach to quantify the manufacturing build time, accuracy, and cost in real time is lacking. In the present research, a generic and near real-time framework for unified additive manufacturing process planning is presented. We have developed computational geometric solutions to estimate tight upper bound of manufacturing process planning decisions that can be analyzed in almost real time. Results of developed computational approach are compared against the optimized process plans to ensure its applicability. Case studies comprising of numerous parts with varying shape, and application area is also outlined.
Construction of a General Motion Editing System for Human Body and Humanoid Robots
Authors: Tsai Ming-June , Chao Jai-Hong , Yang Tzu-Wei
Published: January 2015

In this paper, a general body motion editing system for 3D body motion is constructed. The input of the system accepts any human-like structure according to a specified file designation. The body models are imported using STL format. The user-interface is designed for intuitive 3D manipulation just as operating a video recorder. The software system includes three main functions: motion editing, interpolation, and replication. There are three teaching modes available in world coordinate, local coordinate, and joint coordinate. For editing or retouching existing motions, users can easily choose a key frame to teach, and save the posture as a body motion staff (BMS). Several motion interpolation methods are provided to simulate different body motion characteristics. The BMS between the key frames are generated. The BMS can be used to edit and analyze body motions just like the musical staff does to the music.
Multi-Pulse Chaotic Dynamics of Four-Dimensional Non-Autonomous Nonlinear System for a Truss Core Sandwich Plate
Authors: Zhang Wei , Wu Qi-liang
Published: January 2015

In this paper, an extended high-dimensional Melnikov method is used to investigate global and chaotic dynamics of a simply supported 3D-kagome truss core sandwich plate subjected to the transverse and the in-plane excitations. Based on the motion equation derived by Zhang and the method of multiple scales, the averaged equation is obtained for the case of principal parametric resonance and 1:2 sub-harmonic resonance for the first-order mode and primary resonance for the second-order mode. From the averaged equation obtained, the system is simplified to a three order standard form with a double zero and a pair of pure imaginary eigenvalues by using the theory of normal form. Then, the extended Melnikov method is utilized to investigate the Shilnikov-type multi-pulse heteroclinic bifurcations and existence of chaos. The analysis of the extended Melnikov method demonstrates that there exist the Shilnikov-type multi-pulse heteroclinic bifurcations and chaos in the four-dimensional non-autonomous nonlinear system. Finally, the results of numerical simulations also show that for the nonlinear system of simply supported 3D-kagome truss core sandwich plate with the transverse and the in-plane excitations, the Shilnikov-type multi-pulse motion of chaos can happen and further verify the result of theoretical analysis.
Unified Kinematics Analysis and Analytic Singularity-Free Workspace of a Metamorphic Parallel Mechanism With Controllable Rotation Center
Authors: Gan Dongming , Dai Jian S. , Dias Jorge , Seneviratne Lakmal D.
Published: January 2015

This paper presents a metamorphic parallel mechanism with controllable rotation center in its pure rotation topology. Based on reconfiguration of a reconfigurable Hooke (rT) joint, the rotational center of the mechanism can be altered along the central line perpendicular to the base plane. A unified Dixon resultant based method is proposed to solve the forward kinematics analytically by covering all configurations with variable rotation centers while the rotation motion is expressed using Cayley formula. Then singularity loci are derived and represented in a new coordinate system with the three Rodrigues-Hamilton parameters assigned in three perpendicular directions. Limb-actuation singularity loci are also obtained from row vectors of the Jacobian matrix. By using Cayley formula, analytical workspace boundaries are expressed by including the mechanism structure parameters and input actuation limits. Finally, singularity-free workspace of configurations with variable rotation centers is demonstrated in the proposed coordinate system.
Study on the Offshore Wind Turbine Installation Equipment With 6 Sets of Intelligent Legs
Authors: Ma Chunxiang , Zheng Miaoqi , He Jun , Gao Feng
Published: January 2015

In this paper, a new type of the offshore wind turbine installation equipment is proposed, which has 6 sets of intelligent legs. Each intelligent leg consists of two-UPS and one-UP. Based on the theory of the parallel mechanism, the mechanism of this offshore wind turbine installation equipment with 6 sets of intelligent legs is constructed. We take a set of the intelligent leg for analysis and conducted kinematic analysis and dynamic analysis on the offshore wind turbine installation equipment. Finally, by studying the fuzzy reliability of the kinematic accuracy of a branch, the reliability model of the whole mechanism of the installation equipment combined with the characteristics of installation process is established, and the calculation of the fuzzy reliability of the kinematic accuracy of the whole mechanism is carried out.
Teaching Uncertainty in Design and Analysis Courses
Authors: Du Xiaoping
Published: January 2015

Uncertainty is ubiquitous in engineering, but everything is modeled perfectly in most of engineering courses. It is critical to expose students to the uncertainty reality in engineering design and make them better prepared for facing and handling uncertainty in the real world. In this paper, we discuss the basics of uncertainty and the need of uncertainty education. We then report what we have done in developing uncertainty teaching materials and using them in several engineering design and analysis courses, including Introduction to Design, Dynamics, and Probabilistic Engineering Design, with demonstrative examples. Using good problems are one of the best ways to teach and learn uncertainty, and creating a repository of engineering uncertainty problems is of great value. We also discuss the progress of our effort in the development of the repository.
Protocol Analysis: Studying Physical Manipulatives During Conceptual Design
Authors: Hess Tim , Summers Joshua D.
Published: January 2015

This paper presents a protocol study that explores how individual designers interact with physical elements during mechanical concept ideation and exploration. This protocol study follows three participants individually in a controlled environment as they develop solutions to a presented problem. The goals of this work were 1) to develop a protocol for documenting human interactions with artifacts and 2) to use this protocol to investigate the use of prototypes during conceptual design. The protocol was used to document the actions of study participants in a manner that allowed searching for patterns of behavior. The most common patterns indicated that participants were learning or finding inspiration from the physical artifact interactions that were then applied to their design solutions. In addition, several opportunities for protocol and experimental methods improvements are presented.
Development of a Design for Manufacturing Rules Database for Use in Instruction of DFM Practices
Authors: Phelan Keith , Wilson Crystal , Summers Joshua D.
Published: January 2015

In recent years, there has been a significant push towards “Design for X” (DFX) in modern engineering design practice. One such category that has received a large amount of attention is design for manufacturing. When conducting design for manufacturing, a common tool to assist in the design process is design for a series of design for manufacturing guidelines. While the use of these guidelines, as well as other DFX guidelines, has been shown to be effective, little research has been done with the intent to standardize the guidelines or make them more readily available. In this paper, the authors propose a Design for Manufacturing database tool to assist in the instruction of design for manufacturing guidelines. The development of the database model is discussed, as well as the interface that is used to interact with the database. The tool is then evaluated and conclusions are made with regards to the effectiveness of the database and any future work to increase the functionality. One major addition that is discussed is the adaptation of the database for use in industry, and not just in education, to assist in the engineering design process.
Fall Initiation Criteria for Three-Dimensional Multi-Segmental Model of Biped Robot
Authors: Joo Chang B. , Kim Joo H.
Published: January 2015

A biped mechanism can maintain its balance by redirecting the ground reaction force direction and changing the center of pressure location. In this paper, how the variable inertia in a multibody dynamic model is related to those efforts is investigated and fall initiation criteria in three dimensional space, a balanced state manifold is constructed by using a 3D multi-segmental model. The balanced state domain is constructed by iteratively solving nonlinear constrained optimization problems and finding the velocity extrema at given center of mass positions subjected to certain balancing conditions. The constructed balanced state domain of a multi-segmental model can be used as fall initiation criteria in 3D space and it demonstrates the better balancing maintenance capability of 3D multi-segmental model than the 3D linear inverted pendulum mode.
Joint-Space Dynamic Model of Metabolic Cost With Subject-Specific Energetic Parameters
Authors: Roberts Dustyn , Hillstrom Howard , Kim Joo H.
Published: January 2015

Metabolic energy expenditure (MEE) is commonly used to characterize human motion. In this study, a general joint-space dynamic model of MEE is developed by integrating the principles of thermodynamics and multibody system dynamics in a joint-space model that enables the evaluation of MEE without the limitations inherent in experimental measurements or muscle-space models. Muscle-space energetic components are mapped to the joint space, in which the MEE model is formulated. A constrained optimization algorithm is used to estimate the model parameters from experimental walking data. The joint-space parameters estimated directly from active subjects provide reliable estimates of the trend of the cost of transport at different walking speeds. The quantities predicted by this model, such as cost of transport, can be used as strong complements to experimental methods to increase the reliability of results and yield unique insights for various applications.
Full Rotatability of Watt Six-Bar Linkages
Authors: Wang Jun , Ting Kwun-Lon , Zhao Daxing , Wang Quan , Sun Jinfeng , You Ying , Nie Liangyi
Published: January 2015

The full rotatability of a linkage refers to a linkage in which the input may complete a continuous and smooth rotation without the possibility of encountering a dead center position. Full rotatability identification is a problem generally encountered among the mobility problems that may include branch (assembly mode or circuit), sub-branch (singularity-free) identification, range of motion, and order of motion in linkage analysis and synthesis. In a complex linkage, the input rotatability of each branch may be different while the Watt six-bar linkages may be special. This paper presents a unified and analytical method for the full rotatability identification of Watt six-bar linkages regardless of the choice of input joints or reference link or joint type. The branch of a Watt without dead center positions has full rotatability. Using discriminant method and the concept of joint rotation space (JRS), the full rotatability of a Watt linkage can be easily identified. The proposed method is general and conceptually straightforward. It can be applied for all linkage inversions. Examples of Watt linkage and a six-bar linkage with prismatic joints are employed to illustrate the proposed method.
Large-Scale Topology Optimization Using Parameterized Boolean Networks
Authors: Khetan Ashish , Allison James T.
Published: January 2015

A novel parameterization concept for structural truss topology optimization is presented in this article that enables the use of evolutionary algorithms in design of large-scale structures. The representational power of Boolean networks is used here to parameterize truss topology. A genetic algorithm then operates on parameters that govern the generation of truss topologies using this random network instead of operating directly on design variables. A genetic algorithm implementation is also presented that is congruent with the local rule application of the random network. The primary advantage of using a Boolean random network representation is that a relatively large number of ground structure nodes can be used, enabling successful exploration of a large-scale design space. In the classical binary representation of ground structures, the number of optimization variables increases quadratically with the number of nodes, restricting the maximum number of nodes that can be considered using a ground structure approach. The Boolean random network representation proposed here allows for the exploration of the entire topology space in a systematic way using only a linear number of variables. The number of nodes in the design domain, therefore, can be increased significantly. Truss member geometry and size optimization is performed here in a nested manner where an inner loop size optimization problem is solved for every candidate topology using sequential linear programming with move-limits. The Boolean random network and nested inner-loop optimization allows for the concurrent optimization of truss topology, geometry, and size. The effectiveness of this method is demonstrated using a planar truss design optimization benchmark problem.
Control of a Helicopter Main Gearbox Active Suspension System
Authors: Rodriguez Jonathan , Gaudiller Luc , Chesne Simon , Cranga Paul
Published: January 2015

This paper considers the control of a helicopter gearbox electromagnetic suspension for a complete multibody model of the structure. As the new generation of helicopters includes variable engine RPM during flight, it becomes relevant to add active control in their suspension systems. Most of active system performances derive directly from the controller construction, its optimization to the system controlled and the disturbances expected. An investigation on a FXLMS control algorithm has been made to optimize it in terms of narrow band disturbance rejection. In this paper an active suspension based on DAVI principle is evaluated. Firstly, a multibody model is set up to estimate realistic acceleration levels inside the cabin. Then multiple controllers are tested, minimizing vibrations on different parts of the helicopter structure. The simulations tend to prove that it is possible to implement an effective active suspension with a low power actuator and obtain a significant vibration reduction level for a frequency bandwidth centered at the natural frequency of the original DAVI.
Design of a Linear Bi-Stable Compliant Crank-Slider-Mechanism (LBCCSM)
Authors: Alqasimi Ahmad , Lusk Craig , Chimento Jairo
Published: January 2015

This paper presents a new model for a linear bistable compliant mechanism and design guidelines for its use. The mechanism is based on the crank-slider mechanism. This model takes into account the first mode of buckling and post-buckling behavior of a compliant segment to describe the mechanism’s bistable behavior. The kinetic and kinematic equations, derived from the Pseudo-Rigid-Body Model, were solved numerically and are represented in plots. This representation allows the generation of step-by-step design guidelines. The design parameters consist of maximum desired deflection, material selection, safety-factor, compliant segments’ widths, maximum force required for actuator selection and maximum footprint (i.e. the maximum rectangular area that the mechanism can fit inside of and move freely without interfering with other components). Because different applications may have different input requirements, this paper describes two different design approaches with different parameters subsets as inputs.
Serial Chains of Spherical Four-Bar Mechanisms to Achieve Design Helices
Authors: Giaier Kevin S. , Murray Andrew P. , Myszka David H.
Published: January 2015

This paper presents a method for designing serial chains of spherical four-bar mechanisms that can achieve up to five design helices. The chains are comprised of identical copies of the same four-bar mechanism by connecting the coupler of the prior spherical mechanism to the base link of the subsequent spherical mechanism. Although having a degree of freedom per mechanism, the design methodology is based upon identically actuating each mechanism. With these conditions, the kinematic synthesis task of matching periodically spaced points on up to five arbitrary helices may be achieved. Due to the constraints realized via the spherical equivalent of planar Burmester Theory, spherical mechanisms produce at most five prescribed orientations resulting in this maximum. The methodology introduces a companion helix to each design helix along which the intersection locations of each spherical mechanisms axes must lie. As the mechanisms are connected by rigid links, the distance between the intersection locations along the companion helices is a constant. An extension to the coupler matches the points along the design helices. An approach to mechanically reducing the chain of mechanisms to a single degree of freedom is also presented. Finally, an example shows the methodology applied to three design helices.