Rapid tooling form accuracy estimation using region elimination adaptive search based sampling technique

Purpose - The purpose of this paper is to present the results of an investigation on the straightness, flatness and circularity achievable on two direct RT methods: direct metal laser sintering (DMLS) and stereolithography (SLA). Design/methodology/approach - The steps included manufacturing of samples in eight custom designs with widely used geometric features, intelligent sampling of measurement data, and estimation of corresponding form tolerance by the least square method (LSM). The region elimination adaptive search-based sampling method involved selecting additional sampling points around the maximum deviation in both positive and negative directions from the corresponding reference feature. The LSM solutions, which are commonly used in metrology, are used to estimate the form tolerances considering the best points along with initial measurement data points. Findings - Application of the region elimination search-based sampling method enables form tolerance estimation from a limited number of sample measurements. The study of the DMLS and SLA processes suggested that form accuracy of SLA samples are relatively poor, though their dimensional accuracy is much better than DMLS. Research limitations/implications - This paper was focused on estimating the form tolerances based on limited number of measurement data using region elimination search-based sampling technique. it was assumed that build process parameters suggested by the material and RP systems vendors gives optimum results, presently it does not cover the effect of geometry and other causes of errors on form accuracy. Practical implications - There are two major applications of this investigation and the corresponding knowledge base: evaluating the process capabilities of different rapid tooling processes for comparison and for selecting an appropriate process; and allocating tolerance based on manufacturability considerations, so that the designs are compatible with the process, leading to fewer iterations. A similar approach can be used for updating the capabilities of an improved process as well as include newer processes to develop a comprehensive database of RT process capabilities. Originality/value - In most of the previous benchmarking studies, a given RT process is compared with conventional practice or a limited number of other RT processes, the capabilities in terms of dimensional accuracy, form tolerance, and surface properties (surface finish, wear, and scratch resistance) have not been studied very well. To the best of authors' knowledge, no efforts have been made to estimate form tolerances of the parts or tooling produced by rapid prototyping and tooling processes. Application of the region elimination search-based sampling technique enables estimation of form tolerances that saves costly experimentations. It appears to be completely new in the rapid prototyping and tooling domain

Meson spectrum in a relativistic harmonic model with instanton-induced interaction

On the basis of the phenomenological relativistic harmonic model for quarks, we have obtained the ground-state masses of the light pseudo-scalar and vector mesons. The full Hamiltonian used in the investigation has Lorentz scalar + vector confinement potential, along with one-gluon-exchange potential (OGEP) and the instanton-induced quark-antiquark interaction. A good agreement is obtained with the experimental masses. The respective role of instanton-induced interaction and OGEP for the determination of the meson masses is discussed

Zinser–Engmann–Cole syndrome: Two case report

We report two cases of dyskeratosis congenita. Case 1: An 11-year-old male child presented to us with severe anemia and pancytopenia resulting in cardiac failure, in addition to the classical clinical triad including skin atrophy with mottled pigmentation, nail dystrophy, and oral leukoplakia; he also had palmoplantar keratoderma, adermatoglyphia, mucosal involvement resulting in epiphora, and urethral stricture. Urethral involvement is usually a rare presentation. Case 2: A 5-year-old female child presented with mottled pigmentation, oral leukoplakia, palmoplantar keratoderma with adermatoglyphia, delayed milestones, mental retardation, repeated skin and pulmonary infections, and dental caries along with anemia. In addition, the child had meningocoele which is so far not reported. It is very important to have high index of suspicion about cutaneous markers of dyskeratosis congenita, and its early diagnosis helps to prevent life-threatening systemic complications and to give quality of life

Pseudoepitheliomatous keratotic and micaceous balanitis: A rare condition successfully treated with topical 5-fluorouracil

A 50-year-old man presented with slow-growing dry, rough, micaceous scaly plaque over glans penis, which was compatible with clinical diagnosis of pseudoepitheliomatous keratotic and micaceous balanitis (PKMB) and histologically suggestive of PKMB without cellular atypia. He was treated successfully with topical 5-fluorouracil with complete clearance of lesion in 3 weeks without recurrence for 10 months. PKMB is an extremely rare and interesting condition; only a handful cases have been reported in world literature