Browse Articles

This paper concerns with a method for automatic detection of voids as a result of epoxy die-attach process of a semiconductor chip to the package. A radiographic image is acquired from the inspected semiconductor chip and package and image processing techniques are employed in order to automatically compute the amount of epoxy die-attach voids. Keywords: image processing, X-ray imaging, image segmentation, artificial intelligence

The aim of this study was to evaluate the topography of the main neurovascular bundle located in the posterior aspect of the shoulder and to establish a relatively safe area for a low-risk arthroscopic approach through a posterior portal. A slice anatomy study, using plastinated transparent shoulder joint sections, was performed on ten non-degenerative right shoulder body specimens. Measurements were performed at the level of the suprascapular notch, the coracoid process, and the acromion. The suprascapular nerve was 38.2 ± 0.1 mm, the suprascapular artery 39.4 ± 0.2 mm, and the circumflex scapular artery was 24.8 ± 0.5 mm away from the posterior rim of the acromion at the level of the suprascapular notch. At the level of the coracoid process the suprascapular artery was 34.2 ± 0.5 mm, and the circumflex scapular artery was 50.9 ± 0.3 mm away from the posterior rim of the acromion. Combined measurements of both arteries offered an average distance of 19.8 ± 0.3 mm. The mean distance to the posterior circumflex humeral artery and the axillary nerve was 47.7 ± 1.5 mm and 50.9 ± 0.9 mm, respectively. The present study suggests that, a posterior arthroscopic approach at a level of 4.5 to 5 cm below the posterior rim of the acromion and above the midline of the glenoid joint space poses a low risk for injuries to the neurovascular structures. Keywords: Plastinated cross-sections, arthroscopy, shoulder, axillar nerve

For the optimization of the screw and extrusion process design one need to address issues such the interdependence between the geometrical, hydrodynamic, thermal parameters and material behaviour in each screw zone along with the correlations between successive screw zones. For that purpose, the process parameters (material temperature, barrel temperature, screw speed, pressure development in the screw channel), the screw geometry (flat and compression zones) and the matter behaviour (tribological, thermal and rheological) as a function of temperature and pressure were analyzed. The interdependence between the screw design and the extrusion process parameters from a practical point of view, with the aim of designing the most suitable screw with optimal process parameters for a given processed material, was established. Keywords: extrusion; screw design; optimization; process parameters

The best tibial fixation technique in anterior cruciate ligament reconstruction remains a challenge to be solved. Due to the increased tension on the graft and the poor bone quality, the slippage of the graft is a determining factor of failure. We propose an alternative supplementary, cost-effective and reliable solution to improve the outcome of the grafts fixation. The results obtained on 10 freshly frozen porcine tibiae were significantly improved (p=0.012) compared to the standard method of fixation. The maximal and mean pull-out force was in conformity with the literature. The bones and tendons used simulates the real human ones, thus the results encourage us to extend the application of the method in clinical cases. Keywords: anterior cruciate ligament, tibial fixation reinforcement, graft slippage

This workpaper presents the assessment of the interaction between the dimension of glycol-modified polyethylene terephthalate (PETG) and the attrition of occlusal appliances by determining the degree and area of attrition of dental mouth guards made of PETG plates of different sizes: 0.8mm, 1mm, 1.2mm, 1.5mm, 2mm, 2.2 mm thick. The samples were made by thermoformed using the Erkoform device and inserted into the oral cavity subjects. The evaluation was made 2 weeks, 4 weeks and 6 weeks later. For evaluation it was used coloured occlusal spray. The best results were obtained with the 2 mm thick, but in our study the occlusal appliances with 1,2 mm had good results too. Keywords: occlusal appliances, glycol-modified polyethylene terephthalate (PETG), thermoformed

In order to obtain an ideal smile design for our today subjects, more often the dental treatment requires interdiciplinarity. Recent advances in dental materials and techniques promote the opportunity of bonding orthodontic attachments to surfaces other than enamel, like porcelain crowns, veneers, or bridges. This study aims to compare tensile bond strengths of metal brackets bonding to porcelain fused-to-metal crowns, using two different luting cements (RelyX™ Unicem U200 by 3M ESPE, respectively Blugloo by Ormco) and the same surface conditioning system, as well as to determine the findings’ statistical value. The results evaluated by ANOVA, Tukey and Kruskal-Wallis tests indicated no statistically significant differences among the two cements in terms of tensile bond strength. Keywords: metal brackets, ceramic crowns, tensile bond strength, luting cements

The specific parameters describing the flows of Bingham type rheological fluids through a circular pipe, under the action of a pressure gradient in the direction of the movement are established, using the Non-Standard Scale Relativity Theory approach. In such context, an analytical solution and a numerical application (for KELTAN 4200 — an etilene-co-propilene copolymer) are obtained. The friction effort has two components, one of specific fluid gliding, the other of shearing, depending on transverse speed gradient. In the central area of the fluid movements a particles agglomeration (fluid stopper) occurs, defined by a constantly moving structure. Keywords: rheology, friction effort, polymers, fluid stopper, speed

Shape memory alloys are often used in applications where corrosion resistance property is very important. We can obtain a thin polymer layer using pulsed laser deposition on a nitinol wire with many applications in medical field. The polymer and the shape memory element with a non-metallic thin layer on the surface were analyzed by structural and chemical point of view using scanning electrons microscopy and X-ray dispersive energy analyze. Thermal insights were realized using a differential scanning calorimeter to analyze the polymer behaviour before and after deposition process. Preliminary results on the deposition set-up and the physico-chemical properties of the thin layer are presented and discussed below. Keywords: Shape memory alloys, thin polymer layer, pulsed laser deposition, PMMA

In the following work a correlation was inferred of the effects of material behaviour in different zones of the extruder screw channel with a number of process parameters. Calculus of the average temperature variation of the processed material with length and depth of the screw channel allows effective positioning of intense mixing zones, resulting in enhanced melt thermal homogeneity and product quality. Relationships for the flow-rate of the feeding zone, the specific power and the efficiency of the extrusion process allow the overall performance calculus of the extruder. To increase process efficiency one must reduce the heat loss, Ql which results in energy savings and the decrease of thermal pollution of the environment. It becomes thus possible to replace a certain number z of actual extruders with diameter D, each with a total installed power Nt,1 and flow-rate Gm,1, with a single extruder of the same diameter D assuring a flow-rate Gm = z . Gm,1 and whose total installed power is Nt [ z . Nt,1. Heat lost through the external surface of the heating system of z extruders (z . Q1,l) is higher than that of a single modern extruder. Consequently, process efficiency in the up-graded extruder is higher than that of the extruders, resulting in diminished energy related expenses and cost of the mass unit of extruded product along with less environment pollution. Keywords: extrusion process; extruder performance; output; extruder efficiency; thermal pollution; energy

This paper tackles a ligno-cellulosic composite, whose basic matrix is made out of hemp hurds and mineral binders, as regards the percentage participation of the hurds in the structural stability and thermal-transfer capacity, for a plate- or block-shaped product. The studies, corroborated with laboratory research, aim at ascertaining the use of these products both as lining and as filling material, in the sandwich-type structures, in civil engineering; the materials basis specific to constructions can thereby be achieved, in a wide range, in terms of the thermal-insulation capacity and, implicitly, of the energetic consumption typical of civil, industrial, agro-zootechnical engineering. Keywords: hemp hurds, mineral binders, thermal conductivity