Industrial challenges in grinding

This keynote paper aims at analyzing relevant industrial demands for grinding research. The chosen focus is to understand what are the main research challenges in the extensive industrial use of the process. Since the automotive applications are the most important driving forces for grinding development, the paper starts with an analysis on the main trends in more efficient engines and the changes in their components that will affect the grinding performance. A view from 23 machine tool builders is also presented based on a survey made in interviews and during the EMO and IMTS machine tool shows. Case studies received by the STC G members were used to show how research centers and industries are collaborating. A view from the authors and the final conclusions show hot topics for future grinding research. (C) 2009 CIRP.

Experimental analysis of wheel/workpiece dynamic interactions in grinding

The aim of this work is to study the wheel/workpiece dynamic interactions in high-speed grinding using vitrified CBN wheel and DTG (difficult to grind) work materials. This problem is typical in the grinding of engine valve heads. The influence of tangential force per abrasive grain was investigated as an important control variable for the determination of G ratio. Experiments were carried out to observe the influence of vibrations in the wheel wear. The measurements of acoustic emission (AE) and vibration signals helped in identifying the correlation between the dynamic interactions (produced by forced random excitation) and the wheel wear. The wheel regenerative chatter phenomenon was observed by using the wheel mapping technique. (c) 2008 CIRP.

Fuzzy risk index for power transformer failures due to external short-circuits

A novel methodology to assess the risk of power transformer failures caused by external faults, such as short-circuit, taking the paper insulation condition into account, is presented. The risk index is obtained by contrasting the insulation paper condition with the probability that the transformer withstands the short-circuit current flowing along the winding during an external fault. In order to assess the risk, this probability and the value of the degree of polymerization of the insulating paper are regarded as inputs of a type-2 fuzzy logic system (T2-FLS), which computes the fuzzy risk level. A Monte Carlo simulation has been used to find the survival function of the currents flowing through the transformer winding during a single-phase or a three-phase short-circuit. The Roy Billinton Test System and a real power system have been used to test the results. (C) 2008 Elsevier B.V. All rights reserved.

External shower, Sunshine Beach House, Sunshine Coast

View past timber shutter to external shower.

The determination of the design strength of granite used as external cladding for buildings

This chapter is concerned with acquisition and analysis of test data for determining whether or not the flexural strength of granite cladding under extreme conditions is adequate to assure that reliability requirements are satisfied.

Transformation of external sensilla to chordotonal sensilla in the cut mutant of Drosophila assessed by single-cell marking in the embryo and larva

The cut gene of Drosophila melanogaster is an identity selector gene that establishes the program of development and differentiation of external sense organs. Mutations in the cut gene cause a transformation of the external sense organs into chordotonal organs, originally assessed by the use of immunostaining methods [Bodmer et al. (1987): Cell, 51:293-307]. Because of evidence that axonal projections of the transformed neurons within the central nervous system are not completely switched in cut mutants, the transformation of the four cells making up a sense organ was reassessed using single-cell staining with fluorescent dye and differential interface contrast (DIC) microscopy of the embryo and larva. The results provide strong evidence that all cells of the sense organs are completely transformed, exhibiting the morphologies and organelles characteristic of chordotonal sense organs. A comparison of the structures of external sense organs and chordotonal organs indicates that a number of the differences could be due to the degree of development of common structures, and that cut or downstream genes modulate effector genes that are normally utilized in both receptor types. The possible derivation of insect chordotonal and external sense organs from a receptor type found in crustaceans is discussed in the light of arthropod phylogenetics and the molecular genetics of sense organ development. (C) 1997 Wiley-Liss, Inc.

Movement-related potentials in Parkinson's disease: External cues and attentional strategies

Hypokinetic movement can be greatly improved in Parkinson's disease patients by the provision of external cues to guide movement. It has recently been reported, however, that movement performance in parkinsonian patients can be similarly improved in the absence of external cues by using attentional strategies, whereby patients are instructed to consciously attend to particular aspects of the movement which would normally be controlled automatically. To study the neurophysiological basis of such improvements in performance associated with the use of attentional strategies, movement-related cortical potentials were examined in Parkinson's disease and control subjects using a reaction time paradigm. One group of subjects were explicitly instructed to concentrate on internally timed responses to anticipate the presentation of a predictably timed go signal. Other subjects were given no such instruction regarding attentional strategies. Early-stage premovement activity of movement-related potentials was significantly increased in amplitude and reaction times were significantly faster for Parkinson's disease subjects when instructed to direct their attention toward internally generating responses rather than relying on external cues. It is therefore suggested that the use of attentional strategies may allow movement to be mediated by less automatic and more conscious attentional motor control processes which may be less impaired by basal ganglia dysfunction, and thereby improve movement performance in Parkinson's disease.

Highly integrated and automated high-speed grinding system for printer heads constructed by combination materials

The fabrication of heavy-duty printer heads involves a great deal of grinding work. Previously in the printer manufacturing industry, four grinding procedures were manually conducted in four grinding machines, respectively. The productivity of the whole grinding process was low due to the long loading time. Also, the machine floor space occupation was large because of the four separate grinding machines. The manual operation also caused inconsistent quality. This paper reports the system and process development of a highly integrated and automated high-speed grinding system for printer heads. The developed system, which is believed to be the first of its kind, not only produces printer heads of consistently good quality, but also significantly reduces the cycle time and machine floor space occupation.

Loose abrasive truing and dressing of resin bond diamond cup wheels for grinding fibre optic connectors

A loose abrasive lapping technology was developed for truing and dressing ultrafine diamond cup wheels for grinding spherical end faces of fibre optic connectors. The relative densities of exposed grits and grit pull-outs measured from wheel surfaces prepared using the loose abrasive lapping and the bonded abrasive dressing were compared. It was found that the lapping method with loose abrasives produced wheel surfaces with more exposed grits and less grit pull-outs, especially for finer grit size wheels. For dressing ultrafine grit size wheels, the particle size of the lapping paste should be smaller than the wheel grit size to achieve a better result. It is also found that the wheels dressed using the lapping method demonstrate an excellent grinding performance. (C) 2004 Elsevier B.V.. All rights reserved.

High speed versus conventional grinding in high removal rate machining of alumina and alumina-titania

High removal rate (up to 16.6 mm(3)/s per mm) grinding of alumina and alumina-titania was investigated with respect to material removal and basic grinding parameters using a resin-bond 160 mu m grit diamond wheel at the speeds of 40 and 160 m/s, respectively. The results show that the material removal for the single-phase polycrystalline alumina and the two-phase alumina-titania composite revealed identical mechanisms of microfracture and grain dislodgement under the grinding conditioned selected. There were no distinct differences in surface roughness and morphology for both materials ground at either conventional or high speed. An increase in material removal rate did not necessarily worsen the surface toughness for the two materials at both speeds. Also the grinding forces for the two ceramics demonstrated similar characteristics at any grinding speeds and specific removal rates. Both normal and tangential grinding forces and their force ratios at the high speed were lower than those at the conventional speed, regardless of removal rates. An increase in specific removal rate caused more rapid increases in normal and tangential forces obtained at the conventional grinding speed than those at the high speed. Furthermore, it is found that the high speed grinding at all the removal rates exerted a great amount of coolant-induced normal forces in grinding zone, which were 4-6 times higher than the pure normal grinding forces. (c) 2004 Elsevier Ltd. All rights reserved.

Timing of rotator cuff activation during shoulder external rotation in throwers with and without symptoms of pain

Study Design: Fine-wire EMG rotator cuff onset time analysis in 2 matched groups of throwers with and without pain. Objective: To identify if there is a difference in the activation patterns of the rotator cuff muscles during a rapid shoulder external rotation task between throwers with and without pain. Background: The coordinated action of the rotator cuff is recognized as essential for glenohumeral joint control in the throwing athlete. Identification of abnormalities occurring in muscle activation patterns for injured athletes is relevant when prescribing rehabilitative exercises. Methods and Measures: Twelve throwers with shoulder pain were compared to a matched group of 11 asymptomatic throwers. Participants were matched for age, height, body mass, and habitual activity. Fine-wire EMG electrodes were inserted into the subscapularis, supraspinatus, and infraspinatus. EMG activity was measured during a reaction time task of rapid shoulder external rotation in a seated position. The timing of onset of EMG activity was analyzed in relation to visualization of a light (reaction time) and to the onset of infraspinatus activity (relative latency). Results: In the group with shoulder pain, the onset of subscapularis activity was found to be significantly delayed (reaction time, P = .0018; relative latency, P = .0005) from the onset of infraspinatus activity when compared to the control group. Conclusions: The presence of shoulder pain in these athletes was associated with a difference in the onset of subscapularis EMG activity during a rapid shoulder external rotation movement. This was an initial step in the understanding of the joint protection mechanisms of the glenohumeral joint and the problems that occur in throwers. This information may assist in providing future guidelines for more effective rehabilitation and prevention strategies for this condition.

The degree of external genitalia virilization in girls with 21-hydroxylase deficiency appears to be influenced by the CAG repeats in the androgen receptor gene

Background Women with 21-hydroxylase deficiency present much variability in external genitalia virilization, even among those with similar impairments of 21-hydroxylase (21OH) activity. Objective To evaluate if the number of CAG (nCAG) repeats of the androgen receptor gene influences the degree of external genitalia virilization in women with CYP21A2 mutations, grouped according to impairment of 21OH activity. Patients The nCAG was determined in 106 congenital adrenal hyperplasia (CAH) patients and in 302 controls. The patients were divided, according to their CYP21A2 genotypes, into Groups A and B, which confer total and severe impairment of 21OH activity, respectively. Methods The inactivation pattern of the X-chromosome was studied through genomic DNA digestion with Hpa II. The CAG repeat region was amplified by polymerase chain reaction (PCR) and analysed by GeneScan. Results The nCAG and the frequency of severe skewed X-inactivation did not differ between normal women and patients. The nCAG median in genotype A was 20.7 (IQR 2.3) for Prader I + II, 22.5 (3.6) for Prader III and 21 (2.9) for Prader IV + V (P < 0.05 for Prader III and Prader IV + V). The nCAG median in genotype B was 21.3 (1.1) for Prader I + II, 20.5 (2.9) for Prader III and 22 (2.8) for Prader IV + V (P > 0.05). A significant difference was found regarding the nCAG median in patients presenting Prader III from genotypes A and B. Conclusions We observed great variability in the degree of external genitalia virilization in both CYP21A2 genotypes, and we showed that the CAG repeats of the androgen receptor gene influences this phenotypic variability.

Results of high dose-rate brachytherapy boost before 2D or 3D external beam irradiation for prostate cancer

Background and purpose: To evaluate biochemical control and treatment related toxicity of patients with localized adenocarcinoma of the prostate treated with high dose-rate brachytherapy (HDRB) combined with conventional 2D or 3D-conformal external beam irradiation (EBI). Material and methods: Four-hundred and three patients treated between December 2000 and March 2004. HDRB was delivered with three fractions of 5.5-7 Gy with a single implant, followed by 45 Gy delivered with 2D or 3D conformal EBI. Results: The median follow-up was 48.4 months. Biochemical failure (BF) occurred in 9.6% according to both ASTRO and Phoenix consensus criteria. Mean time to relapse was 13 and 26 months, respectively. The 5-year BF free survival using the ASTRO criteria was 94.3%, 86.9% and 86.6% for the low, intermediate and high risk groups, respectively; using Phoenix criteria, 92.4%, 88.0% and 85.3%, respectively. The only predictive factor of BF in the multivariate analysis by both ASTRO and Phoenix criteria was the presence of prostate nodules detected by digital palpation, and patients younger than 60 years presented a higher chance of failure using Phoenix criteria only. Conclusions: Treatment scheme is feasible and safe with good efficacy. (C) 2011 Elsevier Ireland Ltd All rights reserved. Radiotherapy and Oncology 98 (2011) 169-174

Infection rate and risk factors associated with infections related to external ventricular drain

To describe incidence rates and risk factors associated with external ventricular drain (EVD)-related infections at a tertiary Brazilian teaching hospital. The patient cohort consisted of all patients at a major teaching hospital in Brazil with an EVD during the period 1 April 2007 to 30 June 2008 (15 months). Patients were followed up for 30 days after catheter removal. According to the Center for Diseases Control and Prevention criteria for meningitis/ventriculitis, all of the central nervous system (CNS) infections that occurred during this period could be considered to be meningitis or ventriculitis related to EVD placement. Infection rates were calculated using different denominators, such as (1) per patient (incidence), (2) per procedure, and (3) per 1,000 catheter-days (drain-associated infection rate). Patient demographic data, medical history of underlying diseases, antibiotic prophylaxis usage, American Society of Anesthesiologists Score classification, duration of surgery and hospitalization, length of time the EVD was in place, and overall mortality were evaluated during the study period. A logistic regression model was developed to identify factors associated with infection. A total of 119 patients, 130 EVD procedures, and 839 catheter-days were evaluated. The incidence of infection was 18.3%, the infection rate was 16.9% per procedure, and the drain-associated infection rate was 22.4 per 1,000 catheter-days; 77% of the infections were caused by Gram-negative micro-organisms. Only 75% of patients received antibiotic prophylaxis. The infection rate increased with length of the hospital stay. The length of time the catheter was in place was the only independent risk factor associated with infection (p = 0.0369). The incidence of EVD-related infections is high in our hospital, Gram-negative micro-organisms were the most frequent causal agents identified and length of time that the catheter was in place contributed to the infection rate.