Synchrotron X-ray microdiffraction analysis of proton irradiated polycrystalline diamond films

X-ray microdiffraction is a non-destructive technique that allows for depth-resolved, strain measurements with submicron spatial resolution. These capabilities make this technique promising for understanding the mechanical properties of MicroElectroMechancial Systems (MEMS). This investigation examined the local strain induced by irradiating a polycrystalline diamond thin film with a dose of 2 × 10¹⁷ H⁺/cm² protons. Preliminary results indicate that a measurable strain, on the order of 10^− 3, was introduced into the film near the End of Range (EOR) region of the protons.     

Goal-directed imitation for robots: A bio-inspired approach to action understanding and skill learning

In this paper we present a robot control architecture for learning by imitation which takes inspiration from recent discoveries in action observation/execution experiments with humans and other primates. The architecture implements two basic processing principles: (1) imitation is primarily directed toward reproducing the outcome of an observed action sequence rather than reproducing the exact action means, and (2) the required capacity to understand the motor intention of another agent is based on motor simulation. The control architecture is validated in a robot system imitating in a goal-directed manner a grasping and placing sequence displayed by a human model. During imitation, skill transfer occurs by learning and representing appropriate goal-directed sequences of motor primitives. The robustness of the goal-directed organization of the controller is tested in the presence of incomplete visual information and changes in environmental constraints.     

Costs and investments of implementing and maintaining HACCP in a pasteurized milk plant

Results of an economic study associated with the implementation and maintenance of HACCP in a pasteurized milk plant are presented. The GMP/SSOP pre-requisites were evaluated in the plant. Two HACCP plans were proposed: a first plan was developed under the actual operating conditions, without previous compliance of GMP/SSOP pre-requisites, and a second plan was developed considering compliance of GMP/SSOP. The cost estimation for implementation and maintenance of HACCP, with or without previous adoption of the pre-requisite programs, was performed and a comparative analysis of the estimated values was carried out. The results suggest that a previous compliance of GMP/SSOP pre-requisites is essential for developing an effective HACCP plan with a small number of critical control points, leading to lower costs and investments for implementation and maintenance of HACCP.     

Constraints on monitoring resin flow in the resin transfer molding (RTM) process by using thermocouple sensors

In this study, a thermocouple sensor system was used to monitor the resin transfer molding (RTM) process. These sensors are low-cost and durable; and they do not disturb the resin flow. They can be used if the inlet resin is either hotter or colder than the mold walls. In experiments of this study, much of the hot resin’s internal energy was transferred to cold mold walls by conduction, when the mold parts were made of a material with high thermal conductivity, such as aluminum. A mathematical model based on 1D flow and 2D unsteady energy conservation was developed to investigate the heat transfer between resin and mold walls. The numerical solution of this model is in qualitative agreement with the results of our experiments. The thermocouple sensor system developed is more useful with the following process parameters: low thermal conductivity of mold material, high resin flow rate, high temperature difference between inlet resin and initial mold walls, and high specific heat of resin. However, for the typical use of RTM materials and typical injection parameters, thermocouples should not be preferred over other sensor types and should be used with caution due to the shortcomings investigated in this study.     

Deposition of ZnO thin film on polytetrafluoroethylene substrate by the magnetron sputtering method

Due to the excellent optical and electrical properties, ZnO thin films deposited on flexible substrates can be used as technologically promising electron devices. Polytetrafluoroethylene (Teflon) had many advanced properties, such as high dielectric strength over various frequencies, low dissipation factor, and high surface electrical resistivity, which had made Teflon a competitive polymer choice in a variety of microelectronic applications. In our work, ZnO film was firstly deposited on Teflon substrate by the magnetron sputtering method. X-ray diffraction data revealed that the ZnO grains were highly c-axis-oriented and nanostructured with the size of 10–30 nm, which was in accordance with the experimental result of Scanning Electron Microscopy.     

Ceramers—functional materials for adsorption techniques

Ceramers were prepared by using commercially available polymethyl- and polymethylphenylsiloxanes as starting materials and converting them by pyrolysis in a nitrogen atmosphere to a hybrid state called ceramer. The microstructures were modified by adding prepyrolized polymethylsiloxanes as filler or by using a blowing agent to fabricate foamed ceramers. The porosity characteristics were quantitatively evaluated using nitrogen adsorption whereas the hydrocarbon sorption behaviour was investigated by adsorption and desorption processes via thermogravimetry. For comparison commercial activated carbons, which are especially designed for hydrocarbon adsorption, were characterized in the same way. It turns out that the new ceramer adsorbents can be used as alternative material for activated carbon. Moreover, they show a significant advantage against activated carbon as the adsorbed species can be easily released, e.g. by heating. Therefore, the ceramers are especially suitable for cyclic ad- and desorption processes as it is necessary for storage or purification applications.     

The influence of Johnson–Cook material constants on finite element simulation of machining of AISI 316L steel

In literature, five different sets of work material constants used in the Johnson–Cook's (J–C) constitutive equation are implemented in a numerical model to describe the behaviour of AISI 316L steel. The aim of this research is to study the effects of five different sets of material constants of the J–C constitutive equation in finite-element modelling of orthogonal cutting of AISI 316L on the experimental and predicted cutting forces, chip morphology, temperature distributions and residual stresses. Several experimental equipments were used to estimate the experimental results, such as piezoelectric dynamometer for cutting forces measurements, thermal imaging system for temperature measurements and X-ray diffraction technique for residual stresses determination on the machined surfaces; while an elastic–viscoplastic FEM formulation was implemented to predict the local and global variables involved in this research. It has been observed that all the considered process output and, in particular the residual stresses are very sensitive to the J–C's material constants.     

Entropy generation and thermodynamic optimization of fully developed laminar convection in a helical coil

The present paper analyses the entropy generation of the fully developed laminar convection in a helical coil with constant wall heat flux and presents the optimal design based on the minimum entropy generation principal. The important design parameters, including Reynolds number (Re), coil-to-tube radius ratio (δ) and nondimensional coil pitch (λ) are varied to investigate their influences on the entropy generation. The results presented in this paper cover Re range of 100–10,000, δ and λ range from 0.01 to 0.3. Compared with Re and δ, the coil pitch λ is found to have minor influence on the entropy generation. For a demonstrated case, the minimum entropy generation occurs in the range bounded by Re from 2271 to 4277 and δ from 0.17 to 0.3, within which the irreversibility of the system is lowest and the system performance would be optimum. The details show that there is an optimal Re for a helical coil with a fixed δ; meanwhile for a helical coil flow with a specified Re, the smaller δ should be selected when the Re is larger than 5000, and the larger δ should be selected when the Re is less than 5000. These results provide worthwhile information for heat exchanger designers to find the optimal helical coil design from the viewpoint of the thermodynamic second law.