Search results

This paper describes a modeling strategy and the model development for predicting ion implanted impurity distributions in single‐crystal silicon. Both a computationally efficient semi‐empirical model and a physically‐based, more computationally intense Monte Carlo model have been developed for boron distributions in silicon. The resulting models account very well for the detailed profile dependence on implant dose, tilt angle, and rotation angle in addition to energy.

A comprehensive and computationally efficient modeling strategy for the rapid and accurate simulation of implanted impurity distribution profiles in single‐crystal silicon has been developed. This modeling strategy exploits the advantages of both Monte Carlo simulation and semi‐empirical models by combining the two approaches in a complementary manner. The dual Pearson semi‐empirical model is used to accurately and efficiently model the dose and implant angle dependence of impurity profiles as well as the dependence on energy. This new comprehensive model allows convenient and accurate simulation of implanted boron distribution profiles in single‐crystal silicon as a function of dose, tilt angle, and rotation angle, in addition to ion energy, and it has been demonstrated by implementation in the process simulation code SUPREM III.

Laser sintering of polyamide lattice-based lightweight fairing components for subsequent racetrack testing requires a high quality and a reliable design. Hence, the purpose of this study was to develop a design methodology for such additively manufactured prototypes, considering efficient generation and structural simulation of boundary conformal non-periodic lattices, optimization of production parameters as well as experimental validation.

Multi-curved, sandwich structure-based demonstrators were designed, simulated and experimentally tested with boundary conformal lattice cells. The demonstrator’s non-periodic lattice cells were simplified by forward homogenization processes. To represent the stiffness of the top and bottom face sheet, constant isotropic and mapped transversely isotropic simulation approaches were compared. The dimensional accuracy of lattice cells and demonstrators were measured with a gauge caliper and a three-dimensional scanning system. The optimized process parameters for lattice structures were transferred onto a large volume laser sintering system. The stiffness of each finite element analysis was verified by an experimental test setup including a digital image correlation system.

The stiffness prediction of the mapped was superior to the constant approach and underestimated the test results with −6.5%. Using a full scale fairing the applicability of the development process was successfully demonstrated.

The design approach elaborated in this research covers aspects from efficient geometry generation over structural simulation to experimental testing of produced parts. This methodology is not only relevant in the context of motor sports but is transferrable for all additively manufactured large scale components featuring a complex lattice sub-structure and is, therefore, relevant across industries.

The purpose of this study is to integrate evidence on contributing factors, consequences, in addition to coping mechanisms of depression and anxiety in patients with heart failure.

An integrative review was conducted by searching three main electronic databases: Web of Sciences, MEDLINE and Science Direct. Twenty-four studies met the inclusion criteria and were included in the final review process.

The review identified the most common contributing factors, consequences and coping mechanisms of depression and anxiety in patients with heart failure. Patients with heart failure have high anxiety and depression prevalence rates.

It is recommended to include routine assessment and management of anxiety and depression in heart failure protocols to improve clinical outcomes.

This paper presents a new discretization technique of the hydrodynamic energy balance model based on a finite‐element formulation. The concept of heat source lumping is introduced, and the thermal conductivity model includes the effect of varying both carrier concentrations and temperatures. The energy balance equation is formulated to account for kinetic energy as a convective flow. The new discretization method has the advantage that it allows for assembling the functions out of elementary variables available over elements instead of along element links. Therefore, theoretically, calculation of the Jacobian should be three times faster than by the classic method. Results are given for three examples. The method suffers from mathematical instabilities, but provides a good basis for future work to solve these problems.

The purpose of this paper is to investigate the role of illness-related worries as a mediator among depression, anxiety and self-care in heart failure (HF) patients was the aim of this study.

This study was descriptive and correlational study. In total, 149 patients with HF were selected for sampling in 2016. Patients completed self-care behavior scale, illness-related worries questionnaire and Depression Anxiety Stress Scale (DASS) questionnaires. The Pearson correlation coefficient and Sobel test were also done.

According to the analysis of the Sobel test, the role of illness-related worries as a mediator in the relationship between depression and self-care result was −5.37. Sobel test analysis was done to assess the role of illness-related worries as mediator between anxiety and self-care (6.66). The correlation between depression and self-care was 0.488 (p<0.01); correlation between anxiety and self-care was 0.4 (p<0.01); correlation between anxiety and depression was 0.79 (p<0.01); and the correlation between illness-related worries and self-care was 0.71 (p<0.01).

Illness-related worries can serve as a mediator in the relationship among depression, anxiety and self-care. There was a significant correlation among the research variables. Therefore, educational programs to reduce depression, anxiety and increase self-care should be given priority to for HF patients.

A three‐parameter model for the electronic stopping power of boron in silicon is presented. The model parameters are determined from implantations into amor‐phous silicon and from channeling implantations into <100> and <100> silicon. Simulated boron profiles obtained with the new model, with the Lindhard model, and with the Oen‐Robinson model, respectively, are compared with experimental data on channeling and tilted implantations at 17 and 150 keV.

The effect of a screening oxide layer on 1‐D and 2‐D ion implantation profiles in silicon is investigated using Monte Carlo simulations. Experimental observations of profile broadening by oxide layers are explained by the fact that atoms at lattice positions are less effective in steering ions into channels than atoms at random positions. The influence of the oxide layer on the lateral penetration below a mask is discussed in terms of implantation energy and ion species. A new set of parameters for the electronic stopping of phosphorus and arsenic in silicon is used.

This study aims to investigate the effect of the material thickness and build orientation on the mass transfer of low molecular weight substances through polyamide 12 (PA12) structures produced by laser sintering (LS).

Disc-shaped PA12 sheets having a nominal thickness ranging from 700 to 2,000 µm were built in horizontal, vertical and diagonal orientations and their permeation properties to oxygen and water vapor were measured. The structural properties of the sheets were examined by X-ray micro-computed tomography, differential scanning calorimetry and polarized light microscopy.

All the LS sheets that were investigated had water vapor and oxygen permeation coefficients that are in the range of those of PA12 produced by traditional manufacturing technologies. Despite significant differences in the porosity characteristics, the permeation properties of sheets built in different orientations were similar. The pores seem to have no measurable effect on the mass transfer rates in the sheets, and the transport processes seem to predominantly follow the rules of a regular solution-diffusion mechanism. The results showed a non-significant trend toward thickness-dependent permeation coefficients, which agrees with the observed differences in the crystal structures of the sheets.

The results are an important basis for the qualification of LS technology for direct manufacturing in applications requiring special barrier performance.

This study provides new information on mechanisms of mass transport through LS PA12 and the effect of the material thickness and build orientation. Furthermore, the results enhance understanding of the structural properties of thin polymeric sheets produced by LS.

This paper assesses the impact of this program on the rural women's employment opportunities using data from the 2015 round of the household's living standard survey (HLSS) of Côte d'Ivoire.

In 2013, in order to improve the living conditions of the rural population, the Ivorian government launched the National Program for rural electrification (PRONER) to electrify all localities with more than 500 inhabitants.

The results show that PRONER, while reducing the time allocated to performing household chores, increases women's employment through the reallocation of time to full-time paid work in the agricultural and non-agricultural sectors. The authors also find that the allocation of men's time is not affected by this programme. A possible mechanism that would explain such a pro-women effect is the labour-saving technology introduced to home production as an effect of the reform.

As a limitation, it is important to note that these results were obtained in the specific context of PRONER in Côte d’Ivoire and are not necessarily applicable to rural electrification programmes in other contexts. Furthermore, the choice of other indicators to measure women's empowerment is limited by the quality of the data available. It would be interesting for future research to extend this analysis to include other aspects of women's empowerment and household welfare.

This paper is the first to the author’s knowledge to apply a robust econometric method by combining an inverse probability weighted regression adjustment model with Heckman sample selection method to access a robust causal effect of the PRONER in Côte d'Ivoire.