bluuebunny/crossref_metadata_2025 huggingface dataset:
Degradative enzymes of oral streptococci
Authors: Willcox M.D.P. , Patrikakis M. , Knox K.W.
Published: May 2009

Members of the Streptococcus sanguis group (SSG) and Streptococcus milleri group (SMG) were screened for their ability to produce glycosidase, arylamidase (peptidase), protease, dextranase and glycosyltransferase activities. Species within each group produced unique patterns of activity. The most commonly produced glycosidases were β‐D‐glucosidase, β‐D‐ galactosidase, N‐acetyl‐β‐D‐glucosaminidase and N‐acetyl‐β‐D‐galactosaminidase and the least commonly produced glycosidase activity was β‐fucosidase with Streptococcus intermedius (SMG) being the only species capable of producing the activity. For arylamidase activity, the most commonly produced type was lysine‐arylamidase. Glycosidase and arylamidase activities were localized to particular sub‐cellular fractions. α‐galactosidase was found only in culture supernatant fluids whereas N‐acetyl‐β‐D‐glucosaminidase was found in all fractions; the culture supernatant, cell wall, cell membrane and cytoplasm. No arylamidase activity was seen in culture supernatants. Phe‐arg‐arylamidase was found only in cytoplasmic fractions whereas val‐pro‐arg‐arylamidase was found in cell walls, cell membranes and cytoplasmic fraction. Protease activity was measured as the degradation of bovine serum albumin (BSA) and casein. Casein was degraded by a number of strains whereas no species/strains were able to degrade BSA. Streptococcus intermedius, Streptococcus constellates (SMG), Streptococcus mitior and Streptococcus defectivus (SSG) were the only species that produced hyaluronidase and no species produced chondroitin sulphatase.

The groups were also examined for their abilities to produce glycosyltransferase and dextranase. Strep. sanguis, Streptococcus gordonii, Streptococcus mitis and Streptococcus oralis produced glucosyltransferase and, with the exception of the latter species, fructosyl‐transferase. No species within the SMG was capable of producing either glycosyltransferase. No species within the SSG or SMG was able to produce dextranase activity. The ability of species to produce different types of enzymes was related to their taxonomy, allowing the differentiation of several new taxonomic types within the SSG and may be related to pathogenesis.
The stability of facial osteotomies. 2. Mandibular advancement with bicortical screw fixation
Authors: Hoffman Gary R. , Moloney Frank B.
Published: May 2009

Surgical repositioning of the dento‐skeletal components of the lower third of face, combined with appropriate orthodontic treatment, can be used to improve function and aesthetics. However, the attainment of three‐dimensional stability following corrective jaw surgery continues to be a major problem in the post‐surgical period.

This paper examines the short‐term (6 week postoperative) and long‐term (12 months postoperative) horizontal skeletal stability of bilateral sagittal split mandibular advancement in 15 patients. The mean horizontal advancement of the mandible was 6.1 mm. Six weeks later, a mean continued forward movement of 0.16 mm was identified. The mean relapse at long‐term follow‐up was 0.46 mm (7.5%). Results indicate that rigid bicortical screw fixation of bilateral sagittal split osteotomies undertaken to correct horizontal lower dentofacial deficiency is both statistically and surgically predictable and stable when reviewed up to twelve months after surgery.
The efficacy of Decapinol mouthwash 2 mg/mL in preventing gingivitis
Authors: Yeung Stephen , Groenlund Catherine , Chapple Cheryl , Kemm Angela , Spencer Rick , Grossberg David , Newell Paul , Fitzpatrick Jennifer , Kelty Eva , Movert Rolf
Published: May 2009

In vitro studies and early clinical trials have shown promising results for Delmopinol HCl solution as an effective mouth rinse for reducing experimentally induced gingivitis in the absence of mechanical plaque control. The efficacy of Decapinol mouthwash 2 mg/mL (Delmopinol HCl) in preventing gingivitis in a double‐blind, randomized clinical study with parallel group design was studied. Forty‐seven healthy young adults were randomly assigned to the Delmopinol or placebo groups. After an initial period of four weeks of intensive oral hygiene including biweekly professional cleaning of the teeth and oral hygiene instruction, all subjects achieved a low degree of gingivitis or a plaque score close to zero. At baseline, Bleeding on Probing, Modified Gingival Index and Plaque Index were recorded and the teeth were professionally cleaned. All forms of plaque control were then suspended and subjects were supervised in a one‐minute rinsing of Decapinol mouthwash 2 mg/mL or placebo twice daily. Measurements of efficacy variables were then repeated after two and three weeks treatment and adverse events were recorded. After the study period of three weeks all previous plaque control measures were resumed. At week four, all subjects were reassessed for the resolution of gingival inflammation and where residual gingival inflammation persisted, appropriate treatment was given. Only mild and short‐lasting adverse events were noted for the use of Delmopinol in the study period. However, for all teeth sites measured, significant differences between Delmopinol and placebo groups were found in Bleeding on Probing (p<0.05) and Plaque Index (p<0.0005). The difference was also significant for Modified Gingival Index on the buccal sites (p = 0.04). It can be concluded that 0.2% Delmopinol HCl used as a mouth rinse twice daily is effective in preventing the accumulation of dental plaque on tooth surfaces and the onset of gingivitis.
Major maxillofacial infections. An evaluation of 107 cases
Authors: Bridgeman Andrew , Wiesenfeld David , Hellyar Andrew , Sheldon William
Published: May 2009

A review of 107 cases of acute maxillofacial infections managed at the Royal Melbourne Hospital was undertaken, and details of the presentations, demography, management, and outcomes of these patients are presented. The results indicated that many of the patients had sought treatment from dentists in general practice, and that a significant proportion had received sub‐optimal management prior to referral. Thus a review of the principles of management and guidelines for the referral of patients with maxillofacial infections is also presented.
Temporomandibular disorders. 2. Non‐surgical treatment
Authors: Dimitroulis George , Gremillion Henry A. , Dolwick M. Franklin , Walter John H.
Published: May 2009

There are many treatment modalities for temporomandibular disorders (TMD), most of which are effective in controlling symptoms, at least in the short term. The non‐surgical treatment of temporomandibular disorders continues to be the most effective way of managing over 80 per cent of patients who present with symptoms of temporomandibular pain and dysfunction. In this, the second article in the series, a general overview of the current non‐surgical treatment strategies for TMD will be presented.
Endodontic cellulitis ‘flare‐up’. Case report
Authors: Matusow R. J.
Published: May 2009

Endodontic cellulitis involves facial swelling which can vary from mild to severe and can occur as a primary case or a flare‐up following initial treatment of asymptomatic teeth with periapical lesions. The microbial spectrum in primary cases involves a significant mixture of anaerobic and facultative aerobic microbes, chiefly streptococci. In a previous study, cultures from flare‐up cases, utilizing the same anaerobic techniques as in primary cases, revealed an absence of obligate anaerobes and an 80 per cent incidence of facultative aerobic streptococci. These cases also revealed a significant time lapse from onset of symptoms to the cellulitis phase. No sex or age factors were noted in the primary or flare‐up cases.

The purpose of this case report is to restate a traditional theory, namely, the alteration of the oxidation/reduction potential (Eh), as a major factor for endodontic cellulitis flare‐ups; to confirm the pathogenic potential of oral facultative streptococci; and that asymptomatic endodontic lesions tend to exist with mixed aerobic/anaerobic microbial flora.
The present status of dental rotary cutting performance tests*
Authors: Dyson J. E. , Darvell B. W.
Published: May 2009

Appropriate methods of assessing the cutting ability of handpiece and rotary cutting instrument combinations are needed for research into the processes involved in dental cutting. They are also required for the development of improved devices and recommendations on operation as well as for equipment specification and standards testing.

In reviewing the literature on dental rotary cutting performance testing to evaluate available methods, the factors which may influence clinical cutting behaviour are identified as those related to characteristics of the operator, handpiece, rotary cutting instrument, coolant/lubricant used and workpiece material. Existing industrial cutting theory is of limited help in understanding dental cutting in view of the differences between the control of relevant variables in the two cases. Consideration is given to the ways in which the important variables have (or have not) been controlled in past studies of dental cutting and thus the clinical relevance of available methods evaluated. Serious problems such as the lack of suitable test workpiece materials, as well as deficiencies in current knowledge of operator behaviour, handpiece characteristics and effects of coolant/lubricant application are noted. It is concluded that before improved, clinically relevant tests can be developed, further fundamental research in these areas is essential and that until this is done, further work under arbitrary experimental conditions would be of little value.
An approach to some dilemmas and complications of office oral surgery*
Authors: Leonard Myer S.
Published: May 2009

This article reviews an eclectic collection of problems. There is no particular reason why any one of them was chosen other than that they are more likely to occur in the course of practice than some other complications such as an oro‐antral fistula or trauma to the lingual nerve or tissue emphysema. These latter and some other predicaments were discussed in the course of the talks given by the author at the 28th Australian Dental Congress in March 1995.

The problems discussed in this paper are:

1. Dentoalveolar abscess anaesthesia.

2. Inability to obtain effective anaesthesia.

The complications:

1. Post‐extraction haemorrhage.

2. Syncope.

3. Postoperative infection.
Agenesis of permanent maxillary lateral incisors in South Australian twins
Authors: Townsend Grant , Rogers James , Richards Lindsay , Brown Tasman
Published: May 2009

The frequency of agenesis of maxillary lateral incisors (I2) in a sample of South Australian twins was determined, and associations with gender, zygosity, birthweight and dental crown size were investigated. Ten of the 446 twins examined (2.24 per cent) displayed agenesis of one or both I2, a similar frequency to that reported for Australian singletons. Seven of the ten affected individuals were monozygous female twins, including two pairs, while the three affected dizygous twins were each from different male twin pairs. Five pairs of monozygous twins were identified who displayed varying expressions of normal, small, peg‐shaped or missing I2. These twin pairs displayed disparate birthweights suggesting they may have been mono‐chorionic. These findings are consistent with a multifactorial threshold model linking size and number of I2 with developmental influences modifying phenotypic expression in those monozygous twins whose genetic predisposition places them near to the threshold for agenesis.
The impacted maxillary canine. Further observations on aetiology, radiographic localization, prevention/interception of impaction, and when to suspect impaction
Authors: Jacobs Stanley G.
Published: May 2009

Abstract— Adjacent anomalous or missing maxillary lateral incisors have been implicated in the aetiology of palatally displaced canines by not providing proper guidance to the canine during its eruption. However, a recent review of the literature suggests that the aetiology of palatally displaced canines is genetic in origin. The aetiology of labially impacted canines differs, being due to inadequate arch space. Vertex occlusal radiographs have been recommended for localization but have limitations, and a case is illustrated where this radiograph is deceptive. The prevention/interception of a palatally displaced canine by the extraction of the deciduous canine is best carried out as early as the displacement is detected, mostly soon after 10 years of age. Usually, prevention/interception will avoid the surgical and orthodontic treatment needed to align a palatally impacted canine and may help prevent resorption of the adjacent incisor root. Suspicions that an impaction could occur or has occurred arise a) before the age of 10 years if there is a familial history and/or the maxillary lateral incisors are anomalous or missing; b) after the age of 10 years if there is asymmetry in palpation or a pronounced difference in eruption of canines between the left and right side; or, the canines cannot be palpated and occlusal development is advanced; or, the lateral incisor is proclined and tipped distally; and, on a panoramic radiograph of the late mixed dentition if the incisal tip of the canine overlaps the root of the lateral incisor.
A new design for partial denture circumferential clasp arms
Authors: Brockhurst P. J.
Published: May 2009

Abstract— Partial dentures made from cast cobalt chromium alloys suffer from inadequacies of the retentive spring members. With similar devices made from Type 4 gold alloy, the retentive members are considered satisfactory. Analyses of the combined modulus and strength properties of the alloys show that the lower modulus of elasticity of the gold doubles its overall effectiveness in spring members such as retentive clasp arms. To match this, the strength of cobalt chromium alloys must be doubled. Since this appears unlikely, improvement to the design of the spring members is the only way to rectify this problem.

Retentive clasp arms are required to have adequate elasticity to deflect out of the retentive undercut, adequate stiffness to produce retention and adequate strength to resist accidental damage. Current designs have no published rational basis to meet these requirements, and appear far from ideal.

An analysis of the forces applying to clasp arms and design for uniform stress along the arm produced a shape which differs substantially from the currently used conical taper. The cross‐section dimensions are related to the angular distance from the tip of the clasp. A theoretical comparison of the difference between the theoretical and current designs cannot be made as the current design for tapered clasps is not specific.

It is proposed that improved performance over present clasp designs can be obtained by using clasps of the derived shape. However, the manufacture of clasps of the required complex shape and variable size is impractical, and the next best alternative of clasps of constant cross section along their length was examined. Deflection calculations for this form showed that the loss of deflection in using a clasp of constant cross section instead of the ideal was only 23 per cent.

It is proposed that clasps of constant cross section along their length, with a thickness chosen according to the size of the tooth used for the undercut, will present a significant improvement in clasp performance. Further, it will provide a systematic method of selecting clasp thickness which is not presently available.
Clinical performance of two dentine adhesives: 2‐year results
Authors: Tyas Martin J.
Published: May 2009

Abstract— Scotchbond MP and ART Bond were used without intentional enamel etching to bond a total of 43 resin composite restorations in Class V ‘abrasion/erosion’ lesions. The cumulative loss rates after 6 months, 1 year, and 2 years, respectively, were Scotchbond MP: 9,14, 27 percent; and ART Bond: 0, 5, 5 per cent. These data were not compared because each material was used on different patients. The results support the higher bond strength to dentine in the laboratory of Scotchbond MP compared with its predecessor Scotchbond 2. There was a slight but clinically insignificant amount of enamel marginal staining for both products after 2 years, confirming the necessity to etch the enamel for effective marginal sealing.
Pulp response in primary teeth with deep residual caries treated with silver fluoride and glass ionomer cement (‘atraumatic’ technique)
Authors: Gotjamanos Theo
Published: May 2009

Abstract— Histological assessment of the dental pulps of 55 carious primary teeth was carried out 3 to 56 months after treatment by the ‘atraumatic’ technique involving application of 40 per cent silver fluoride to residual caries followed by restoration with glass ionomer cement. Fifty of the 55 teeth examined showed a favourable pulpal response, including presence of abundant reparative dentine and a wide odontoblast layer. Histological comparisons were made between these teeth and others not treated with silver fluoride but restored with glass ionomer cement, amalgam or zinc oxide and eugenol.

Possible mechanisms of the action of silver fluoride in arresting residual caries are discussed. The question of whether or not treatment of carious dentine with silver fluoride represents a biologically acceptable clinical procedure cannot be answered on the basis of pulpal histology alone. The very high concentration of fluoride in commercial preparations of silver fluoride raises several questions concerning its clinical safety.
Intra‐oral distribution and impact of caries experience among South Australian school children
Authors: Slade Gary D. , Spencer A. John , Davies Michael J. , Burrow David
Published: May 2009

Abstract— This report describes the intra‐oral distribution of caries and frequency of reported toothache using data from 9690 South Australian children aged 5–15 years. School dental therapists and dentists recorded dmfs and DMFS data and a questionnaire to parents sought information about toothache and its impact. There were higher levels of cartes experience in deciduous teeth (mean 6‐year‐old dmfs=2.61) compared with permanent teeth (mean 12‐year‐old DMFS=1.15). In the deciduous dentition: between 11.4 per cent (9‐year‐olds) and 37.7 per cent (5‐year‐olds) of total dmfs was present as untreated decay; between 39.1 per cent (7‐year‐olds) and 42.8 per cent (10‐year‐olds) occurred on interproximal surfaces; and between 2.0 per cent (10‐year‐olds) and 27.8 per cent (5‐year‐olds) occurred in anterior teeth. In the permanent dentition, the majority of permanent caries experience occurred as fillings in pits and fissures of first molars and involved a single surface. Between 11.8 per cent (5‐year‐olds) and 31.8 per cent (12‐year‐olds) of children had a reported history of toothache, although the figure exceeded 50 per cent among children with all three forms of pit/fissure, interproximal and smooth‐surface caries experience. The observed pattern of caries provides the basis for continued use of fissure sealants as a preventive measure among school children.
Removable prosthodontics: A survey of practices and attitudes among South Australian dentists
Authors: Coates Anthony J. , Moore Kevin R. , Richards Lindsay C.
Published: May 2009

All dentists registered in South Australia were surveyed in July 1993 in relation to removable prosthodontics. The replies indicated that removable prosthodontics constituted a significant part of most dental practices. Most dentists felt that removable prosthodontics should be an essential part of the undergraduate curriculum. They felt that more expertise is now required to manage the treatment of the ageing population with either their first or replacement removable prostheses. The majority of dentists felt that their own undergraduate training had equipped them well to manage removable prosthodontic treatment for their patients; however, many helpful suggestions were made on areas that they thought required more emphasis.
Examination of periodontal tissues by a cutting‐grinding technique
Authors: Günhan Meral , Günhan Ömer , Celasun Bülent , Safali Mükerrem
Published: May 2009

The decalcification process removes the mineralized part of the dental hard tissues, making the histologic examination of enamel‐associated tissues less than optimal. The cutting‐grinding technique allows preparation of histologic slides with well preserved dental hard tissues together with their surrounding soft tissue components. In this paper, the histologic appearances of undecalcified teeth and their associated periodontal tissues prepared using the cutting‐grinding technique are described.
Anatomical considerations in the diagnosis and management of acute maxillofacial bacterial infections
Authors: Bridgeman Andrew , Wiesenfeld David , Newland Stuart
Published: May 2009

General dentiste are frequently called upon to manage maxillofacial infections. Such infections are usually well localized in their initial stages but can spread to become severe and potentially life‐threatening. This paper discusses the anatomical basis of the spread of these infections and techniques relevant to the rational management of these serious conditions.
Prevalence of orofacial injuries and use of mouthguards in high school Rugby Union*
Authors: Chapman P. J. , Nasserr B. P.
Published: May 2009

In Australia there is a tradition of early involvement of children in contact sports. Mouthguards are known to reduce the risk of dental and associated injuries — however, Australian studies of the use of mouthguards in contact sports and the prevalence of dental and associated injuries have only focused on adult participants. Previous studies of high school Rugby Union players in New Zealand have shown that between 13 and 15 per cent had previously sustained dental injury while between 30 and 37 per cent wore mouthguards regularly. One hundred and thirty Rugby Union football players attending a large high school in Brisbane participated in this survey. All believed in the safety value of mouthguards in football. All of the players in the four open teams and the majority of players in the four under‐age teams wore mouthguards, and the incidence of dental injury was very low, approximately 4 per cent. These and other results will be presented and compared with previous similar studies.
Hypodontia of the permanent dentition. Case reports
Authors: Cameron John , Sampson Wayne J.
Published: May 2009

Hypodontia has been observed as one of the most common human dental developmental anomalies. It may be defined as agenesis of one or more teeth. The prevalence in the permanent lower central and lateral incisor region is low, ranging from 0.23 per cent to 0.08 per cent, respectively. This is compared with an overall incidence of hypodontia of 3.49 per cent. However, significant racial variation occurs. Treatment options generally available are: no treatment, closure of spaces orthodontically, or prosthetic replacement. Aetiology, associated anomalies, and factors involved in treatment choice are discussed. A report of four cases of hypodontia of the permanent lower anterior teeth and their orthodontic management is presented.
An unusual facial sinus
Authors: Cheung L. K. , Samman N. , Lee E.
Published: May 2009

An unusual presentation of a chronic suppurative granuloma on the alar base area originating from a maxillary lateral incisor is reported. Treatment involved adequate endodontic therapy with simultaneous apical surgery and excision of the granuloma and sinus tract. Awareness of the possible dental origin of facial sinuses, despite their unusual location, is emphasized.
Temporomandibular disorders. Part 3. Surgical treatment
Authors: Dimitroulis George , Dolwick M. Franklin
Published: May 2009

Surgery of the temporomandibular joint has a small but nonetheless important role in the overall management of temporomandibular disorders. Appropriate case selection is the mandatory requirement for successful surgical intervention in order to achieve the desired outcome of treatment, such as relief of symptoms and improved function. In this, the third article in the series, a general overview of the current surgical treatment modalities for temporomandibular disorders will be presented.
Fluoride content of infant formulae in Australia
Authors: Silva Margarita , Reynolds Eric C.
Published: May 2009

The prevalence of dental fluorosis in Australia and the United States of America has increased in both optimally fluoridated and non‐fluoridated areas. This has been attributed to an increase in the fluoride level of food and beverages through processing with fluoridated water, inadvertent ingestion of fluoride toothpaste, and the inappropriate use of dietary supplements. A major source of fluoride in infancy is considered to be infant formula which has been implicated as a risk factor for fluorosis in a number of studies. In this study the fluoride content of the infant formulae commonly used in Australia was determined. The acid diffusible fluoride of each powdered formula was isolated by microdiffusion and measured using a fluoride ion‐specific electrode. The fluoride content of milk‐based formulae ranged from 0.23 to 3.71 μg F/g and for soy‐based formulae from 1.08 to 2.86 μg F/g. When reconstituted, according to the manufacturer's directions, with water not containing fluoride, the formulae ranged in fluoride content from 0.031 to 0.532 ppm, with the average fluoride content 0.240 ppm. Using average infant body masses and suggested volumes of formula consumption for infants 1–12 months of age, possible fluoride ingestion per kg body mass was estimated. None of the formulae, if reconstituted using water containing up to 0.1 ppm F, should provide a daily fluoride intake above the suggested threshold for fluorosis of 0.1 mg F/kg body mass. However, W reconstituted with water containing 1.0 ppm F they should all provide a daily fluoride intake of above the suggested threshold for fluorosis with intakes up to 2–3 times the recommended upper ‘optimal’ limit of 0.07 mg/kg body mass. Under these conditions the water used to reconstitute the formulae would provide 65–97 per cent of the fluoride ingested. These figures are likely to be overestimates due to the intake of nutrients from other sources reducing formulae consumption and also due to the lower bioavallability of fluoride from milk‐based formulae. Further, it is generally believed that the maturation stage of enamel formation is the critical period for fluorosis development by chronic, above‐threshold fluoride exposure. The maturation stage for the anterior permanent teeth, however, is after the first twelve months of life where fluoride intake from infant formula consumption per kg body mass is highest. The level of fluoride in the commonly used Australian formulae would suggest that infant formula consumption alone is unlikely to be a risk factor for dental fluorosis in a non‐fluoridated community, but could make a major contribution to an infant's daily fluoride intake. However, prolonged consumption (beyond 12 months of age) of infant formula reconstituted with optimally‐fluoridated water could result in excessive amounts of fluoride being ingested during enamel development of the anterior permanent teeth and therefore may be a risk factor for fluorosis of these teeth.
An in vitro study of the distribution of silver and fluoride following application of 40 per cent silver fluoride solution to dentine
Authors: Afonso Fernando , Gotjamanos Theo
Published: May 2009

An in vitro test system involving application of 40 per cent silver fluoride solution to prepared cavities of moderate depth in extracted teeth failed to demonstrate the passage of significant amounts of fluoride into the dental pulp, despite a very high concentration of fluoride (100 000 ppm) in the applied solution. The test system used may not be conducive to quantitative investigation of ionic transfer because of disruptions to pulp circulation and fluid flow through dentine following tooth extraction. For this reason, the results are inconclusive as to whether or not application of 40 per cent silver fluoride as a cavity varnish or liner, and its use in the ‘atraumatic’ technique for treating deep caries, can be considered safe clinical procedures.
Crashworthiness Design Using Topology Optimization
Authors: Patel Neal M. , Kang Byung-Soo , Renaud John E. , Tovar Andrés
Published: May 2009

Crashworthiness design is an evolving discipline that combines vehicle crash simulation and design synthesis. The goal is to increase passenger safety subject to manufacturing cost constraints. The crashworthiness design process requires modeling of the complex interactions involved in a crash event. Current approaches utilize a parametrized optimization approach that requires response surface approximations of the design space. This is due to the expensive nature of numerical crash simulations and the high nonlinearity and noisiness in the design space. These methodologies usually require a significant effort to determine an initial design concept. In this paper, a heuristic approach to continuum-based topology optimization is developed for crashworthiness design. The methodology utilizes the cellular automata paradigm to generate three-dimensional design concepts. Furthermore, a constraint on maximum displacement is implemented to maintain a desired performance of the structures synthesized. Example design problems are used to demonstrate that the proposed methodology converges to a final topology in an efficient manner.
Multirate Estimation for Discrete Processes Under Multirate Noise With Application to the Grinding Process
Authors: Lee Cheol W.
Published: May 2009

Asynchronous measurement of process output characterizes a series of discrete process cycles in batch production. A multirate Kalman filtering scheme was proposed by Lee (2008, “Estimation Strategy for a Series of Grinding Cycles in Batch Production,” IEEE Trans. Contr. Syst. Technol., 16(3, pp. 556–561)) for estimating immeasurable variables through integration of other sensor signals with postprocess inspection data. In this paper, a new state-space model structure for a series of discrete process cycles is proposed based on a semicontinuous system under the process noise of multiple frequencies due to the within-cycle drift and the cycle-to-cycle variation. An improvement is made to the previous estimation scheme by deriving the propagation of estimation errors between consecutive cycles under the multirate noise. Following a simulation demonstrating the advantage of the proposed change, experiments are conducted on an actual grinding process to validate the estimation scheme.
Design of a Shape Memory Alloy Actuated Compliant Smart Structure: Elastica Approach
Authors: Sreekumar M. , Nagarajan T. , Singaperumal M.
Published: May 2009

Large displacement static analysis of a fully compliant spatial mechanism is presented here. This mechanism is made up of a superelastic nitinol pipe as its compliant structural member and actuated by three shape memory alloy (SMA) wires. The coupled effect of the force developed by the SMA actuation and the force required for elastica deflection is simplified by incorporating the geometric parameters of the mechanism using a deflection plane approach. An iterative algorithm with elliptical integration has been developed, which is suitable for a wider range of actual and arbitrary inputs. The solutions are obtained for the effect of one-wire and two-wire actuation methods. Results obtained from the deflection plane approach and simulation have been compared and found that the relative error is less than 1% within the safe operating range of 5% strain value recommended for SMA actuators. Based on the analytical and simulation inputs, the mechanism is miniaturized further with the aim of increasing its workspace and is fabricated for further experimental investigations.
Modeling the Design Process of Product Variants With Timed Colored Petri Nets
Authors: Xu Qianli , Jiao Jianxin (Roger)
Published: May 2009

The design process of product variants involves complicated task planning that needs to leverage a number of design activities and resources. A comprehensive product variant design process model is imperative for capturing the semantics underlying product variants and subsequently supporting design process planning decisions. This paper applies timed colored Petri nets (TCPN) to model various elements of the product variant design process. The TCPN model performs as a generic design process platform from which alternative configurations of process plans can be derived and further converted to discrete-event simulation models for evaluation. A case study of car dashboard family design demonstrates that the TCPN design process model can effectively represent the elements of multiple design processes and support design task planning while leveraging design activities and resource allocation at the entire product family level.
“Non-Scientific” Experimentation in Design of Product and Process
Authors: Goh T. N. , Guo Liqing
Published: May 2009

College students in engineering and physical sciences are often educated in “scientific” methods of experimentation. For many years there have been advocates of statistical tools for research and development in design as well as prototyping and testing, yet their acceptance into engineering and technical curricula has been limited. The discussions in this paper explain the rationale for the use of statistical methods such as statistical design of experiments for superior product and process performance. Both educators and students in technical fields would realize that data-driven tools are indeed useful and important for designed-in quality and reliability. In fact, savings and opportunities for enhanced performance via virtually cost free techniques could often be discovered as well. The approach taken, largely based on statistical design of experiments, could be perceived to go against ingrained concepts of “scientific methods” but the efficacy of new product and process design can be readily explained and demonstrated. Such an understanding would be extremely useful in formulating effective design curricula at both graduate and undergraduate levels.
Influence of Misalignments on EHD Lubrication in Hypoid Gears
Authors: Simon Vilmos V.
Published: May 2009

The thermal elastohydrodynamic analysis of lubrication is applied to investigate the influence of misalignments of the meshing members on EHD lubrication in hypoid gears. The calculation is based on the simultaneous solution of the Reynolds, elasticity, energy, and Laplace’s equations. The full thermal EHD lubrication analysis is applied, therefore, the oil viscosity variation with respect to pressure and temperature and the density variation with respect to pressure are included. The real shape of the gap existing between the contacting tooth surfaces is treated, based on gear teeth geometry defined by the gear processing method and including the misalignments of mating members. By using the corresponding computer program, the influence of pinion’s running offset and axial adjustment errors, and angular position error of pinion axis on maximum oil film pressure and temperature, EHD load carrying capacity, and on power losses in the oil film is investigated. The obtained results are presented and discussed.
Numerical Investigation on Traveling Wave Vibration of Bevel Gears
Authors: Carmignani Costantino , Forte Paola , Melani Gabriele , Di Carlo Giovanni
Published: May 2009

Aircraft transmissions have the peculiar characteristics of light structures and high operating speeds, therefore relatively low flexural natural frequencies and high excitation frequencies due to rotation and meshing. Thus some dynamic phenomena, such as traveling wave vibration (TWV), can be more easily encountered. However few papers can be found in the literature on TWV of gears while on the contrary it might be a problem especially for gears having thin rim and disk. This paper deals with the simulation of the disk TWV of bevel gears. 3D FEM is used to obtain the natural modes and frequencies of the gear. The response of a simplified non-rotating model of two meshing gears was entirely simulated in an Ansys environment. The numerical tests were performed considering a variable torque applied to one of the gears, the other being constrained, accounting for the meshing excitation. To simulate the rotating contact condition with respect to the gear reference systems, the dof of the nodes in contact of the two gears were coupled. Preliminary tests were performed considering one of the two gears rigid. The simulation of the TWV of gears makes it possible to identify the most critical conditions for stress and fatigue in the gear disks and therefore estimate the gear structural reliability.
Modeling Shape Errors of Worm Gears
Authors: Groma Istva´n , Bercsey Tibor
Published: May 2009

The development of space research, military and medical technology requires more exact and more efficient power transmission techniques. In order to create efficient gearings it is important to produce gear parts with proper geometrical shape it is especially true for worm gears. Our goal was to work out a mathematical model for handling and classifying shape errors coming from worm gear manufacturing. The model provides a new approach to recon the confidence level and the flaws of worm gear manufacturing methods. The concept of a corresponding software system for analyzing the geometrical effect of different manufacturing inadequacies is also considered.
Application of Modified PID Neural Network to Discrete Nonlinear System Control
Authors: Li Shouju , Liu Yingxi , Huo Chenfang
Published: May 2009

An improved PID neural network-based controller is designed and analyzed for the classes of single-input nonlinear system and multi-input discrete system. In order to deal with the local minimum problem in training neural network with back-propagation algorithm and to enhance controlling precision, neural network’s weights are adjusted by optimization algorithm. The controller employs a PID neural network instead of estimating the unknown plant nonlinearities on-line. When compared to other nonlinear modeling techniques for control purposes, it has several specific advantages that make it ideally suited to particular applications. Tow examples are used to demonstrate the performance and properties of the proposed scheme. The simulation results show that the proposed controller with improved PID neural network is flexible and efficient in the control of discrete nonlinear dynamic system.
Profile Shifted Conical Involute Gear With Deep Tooth Depth
Authors: Ohmachi Tatsuya , Uchino Atsushi , Komatsubara Hidenori , Saito Makoto , Saiki Kohei , Mitome Ken-Ichi
Published: May 2009

This paper proposes a new design method for profile shifted conical gear with deep tooth depth. This method has two new concepts. First, this method is based on the designed pitch point where the rack shift coefficient is not zero. Second, this method is based on the theory of nonintersecting bevel gear such as hypoid gear, to decide the mounting dimensions of the profile shifted conical involute gears with deep tooth depth. The profile shifted conical involute gears have the designed pitch point that is not the standard pitch point. Limits of the rack shift coefficient and the facewidth, for the undercut and the zero top land, are clarified. Next, the production system is shown, and several typical test gears are manufactured. Paths of contact between tooth surfaces of profile shifted conical gears are obtained by tooth bearing tests. As a result, the measured value of limits of the rack shift coefficient and the facewidth on the manufactured tested gears are in good agreement with the theoretical ones. Moreover, test results of tooth bearing are in good agreement with the theoretical ones.
Influence of Equivalence Dynamic Parameters Variation About Behavior Structure of Milling Machine Tools
Authors: Pop Petru A.
Published: May 2009

This paper has presented a study about behavior structure at universal precision milling machine for tool-shop by the variation of machine’s Equivalence Dynamic Parameters (EDP). These parameters of milling machine: equivalent mass – m [kg], equivalent damping constant – c [N/ms−1], equivalent stiffness – k [N/m], have been determined by experimental tests and from calculations, obtaining a exactly range values for each parts. All these had been calculated in function of eigenvalues of milling machine-ωn, which had been determined by experimental tests and mathematical model of dynamic milling process. For that, has been created an original program “Study mck”, which is used by SIMULINK program from MATLAB R14.v7.01 system. Then were executed 11 simulation tests, which were done by certain combinations of m, c, k values and cutting forces parameters, recorded approximately 300 diagrams. The results were significant has determined the chatter frequency very close to eigenvalues of machine by an original method, which had confirmed the experimental measures and analytical calculus and certain solution for improving the dynamic structure of milling machine by its equivalent dynamic parameters.
Investigation of the Meshing Conditions of a Flat Wheel Harmonic Gear Drive
Authors: Krisch Robert
Published: May 2009

The function principle of the flat wheel harmonic gear drive is similar to the basic principle of the classical harmonic drives. The flexible and the solid gear of the drive are coaxial flat wheels. The rotating wave generator deforms periodically and elastically different portions of an annular face gear on the flexible member in axial direction into engagement with teeth on an annular face gear on the solid member. The numbers of teeth of the face gears are different. An analytical method is introduced, that investigates meshing conditions of flat-wheel harmonic drives. The numbers of the connected teeth taking part in the load-transmission and the tangential component of the acting force on them in the range of tooth engagement are calculated. It depends on the loading torque, so calculations were launched at different levels of torques in case of various parameters. The tooth flanks were approximated by planes. Results are compared with the results of calculations based on finite element analyses.
Effect of an Original Gear Mesh Modeling on the Gearbox Dynamic Behavior
Authors: Rigaud Emmanuel , Perret-Liaudet Joe¨l , Mecibah Mohamed-Salah
Published: May 2009

Prediction of the vibratory and acoustical behavior of gearboxes is generally based on characterization of the excitation sources, overall modeling of the gearbox, modal analysis and solving of the parametric equations of motion generated by these models. On the building process of such large degrees of freedom models, the elastic coupling induced by the gear mesh is generally described by the parametric meshing stiffness k(t) along the line of action. This kind of model is not able to take into account the load distribution along the tooth face width, even though the resulting moment can constrain rotational angles associated to wheels tilting and flexural deformation of shafts. The scope of this study is to introduce the coupling terms between wheels associated to these phenomena. Some examples show how they can influence the gear modal characteristics and dynamic response and, consequently, the vibratory and acoustical response of the gearbox.
Study on the Walking Support Machine Indoors by Assisting Whole Legs
Authors: Tanaka Eiichirou , Ikehara Tadaaki , Nagamura Kazuteru , Ikejo Kiyotaka , Sakamoto Takeshi , Inoue Yusuke , Saegusa Shozo
Published: May 2009

There is currently research to support the construction of a walking assist machine, which machine uses a spatial parallel link mechanism for the elderly or rehabilitants. The flat steps of the assist machine move in parallel with the ground and can support the legs of a person including the soles. We developed a prototype and designed to assist people walking at up to fifty percent power. To grasp the walking phase of each leg of the equipped person, pressure sensors were laid under the thenar eminence and the heel of the sole, and the pressure variation at each sensing point was measured. For safety support, we developed a control method of the walking assist machine to fit the motion in phase by phase. Furthermore, in order to support walking indoors, we investigated the assist methods of turning around during walking and walking on a slope or stairs. A flexible link was installed in the mechanism for taking into account the twisting motions of the waist and ankle. To grasp the behavior of turning around during walking of the equipped person, pressure sensors were attached outside of the flexible link in both crural parts of the machine. As a result of the experiment wearing the machine, the equipped person could turn around during walking at will. To confirm the validity of the supporting method, muscle activity of the leg while wearing the walking assist machine evaluated by using the surface electromyography (called as “EMG”), and calculated the ratio of the integrated EMG (called as “IEMG”) with and without the walking assist machine. The initial results show that the activities of the rectus femoris muscle and the tibialis anterior muscle can be held to approximately 60 percent by wearing the walking assist machine. Furthermore, in order to support walking indoors, we investigated the assist methods of walking on a slope or stairs. The machine was equipped with a gyro sensor and an ultrasonic sensor; the angle of the slope and the size of stairs could recognize and the machine could be controled according to the signals from the sensors. As a result of the experiment wearing the machine, the equipped person could walk on a slope or stairs at will. The subject assisted with the machine was able to walk on a slope up to the angle of plus or minus fifteen degrees.
Wear of Spur Gears Having a Dithering Motion and Lubricated With a Perfluorinated Polyether Grease
Authors: Krantz Timothy , Oswald Fred , Handschuh Robert
Published: May 2009

Gear contact surface wear is one of the important failure modes for gear systems. Dedicated experiments are required to enable precise evaluations of gear wear for a particular application. The application of interest for this study required evaluation of wear of gears lubricated with a grade 2 perfluorinated polyether grease and having a dithering (rotation reversal) motion. Experiments were conducted using spur gears made from AISI 9310 steel. Wear was measured using a profilometer at test intervals encompassing 10,000 to 80,000 cycles of dithering motion. The test load level was 1.1 GPa maximum Hertz contact stress at the pitch-line. The trend of total wear as a function of test cycles was linear, and the wear depth rate was approximately 1.2 nm maximum wear depth per gear dithering cycle. The observed wear rate was about 600 times greater than the wear rate for the same gears operated at high speed and lubricated with oil.
Load Distribution Model for Involute Internal Gear Sets
Authors: Pedrero Jose´ I. , Pleguezuelos Miguel , Aguiriano Silvia
Published: May 2009

This paper presents a new model of load distribution for involute, internal gear drives, which takes into account the changing rigidity of the pair of teeth along the path of contact. The model has been obtained from the minimum elastic potential criterion, resulting in a non-uniform load distribution along the line of contact (for helical gears), as well as among several pairs in simultaneous contact. A study of the nominal contact stress, including the calculation of the determinant load conditions, is also presented.