Search for: All records

Abstract While many tools and methodologies for assessing social impact exist and are used in the social science and global development fields, there is a lack of standard methods for considering the broader social impact of products in the engineering community. Some reasons these methods are not as widely used in the engineering community include designers not being aware of the methods, or methods not being widely applicable. The purpose of this research is to help designers and researchers find relevant design tools and methods for implementing social impact considerations. This is done through the classification of 374 papers in the Engineering for Global Development (EGD) literature along several dimensions including method purpose, industry sector, social impacts considered, sustainable development goals, paper setting, and data inputs required. This article describes how designers and researchers can use this set of classified papers to locate relevant design tools and methods to improve social impact considerations in their work. 

The impact of 1.8 MeV proton irradiation on metalorganic chemical vapor deposition grown (010) β-Ga2O3 Schottky diodes is presented. It is found that after a 10.8×1013cm−2 proton fluence the Schottky barrier height of (1.40±0.05 eV) and the ideality factor of (1.05±0.05) are unaffected. Capacitance–voltage extracted net ionized doping curves indicate a carrier removal rate of 268±10cm−1. The defect states responsible for the observed carrier removal are studied through a combination of deep level transient and optical spectroscopies (DLTS/DLOS) as well as lighted capacitance–voltage (LCV) measurements. The dominating effect on the defect spectrum is due to the EC-2.0 eV defect state observed in DLOS and LCV. This state accounts for ∼75% of the total trap introduction rate and is the primary source of carrier removal from proton irradiation. Of the DLTS detected states, the EC-0.72 eV state dominated but had a comparably smaller contribution to the trap introduction. These two traps have previously been correlated with acceptor-like gallium vacancy-related defects. Several other trap states at EC-0.36, EC-0.63, and EC-1.09 eV were newly detected after proton irradiation, and two pre-existing states at EC-1.2 and EC-4.4 eV showed a slight increase in concentration after irradiation, together accounting for the remainder of trap introduction. However, a pre-existing trap at EC-0.40 eV was found to be insensitive to proton irradiation and, therefore, is likely of extrinsic origin. The comprehensive defect characterization of 1.8 MeV proton irradiation damage can aid the modeling and design for a range of radiation tolerant devices.

 

Active materials couple a stimulus (electrical, magnetic, thermal) with a mechanical response. Typical materials such as piezoelectrics strain as bulk materials to the stimuli. Here we consider an undulation created by heterogeneous deformation within a magnetic shape memory alloy (MSM) transducer. We study the mechanical response of an MSM element vs. two surface treatments: a polished state with minimal surface stresses, and a micropeened state with compressive surface stress. The polished element had a sharp-featured, faceted trough shape. The micropeened element had a smooth trough shape and an additional crest. The undulation was created by a rotating localized magnetic field, which caused heterogeneous variation of the twin-microstructure. For the polished and micropeened elements, the twin-microstructures were coarse and fine, respectively. For the polished element, the undulation moved by the nucleation of a few twin boundaries, which traveled along the entire element. For the micropeened sample, the twin boundaries moved back and forth over a short distance, thereby creating a dense twin lamellar, which formed the trough. The motion of the lamellar approximated the single thick twin while allowing additional degrees of freedom due to increased mobile interface density and different initial conditions of domain volume fraction. The dense twin microstructure also smoothed the magnetic flux pattern. The undulation amplitude was about 40 μm for the sample in both treatments. 

Abstract The impact of engineered products is a topic of concern in society. Product impact may fall under the categories of economic, environmental or social impact, with the last category defined as the effect of a product on the day-to-day life of people. Design teams lack sufficient tools to estimate the social impact of products, and the combined impacts of economic, environmental and social impacts for the products they are designing. This paper aims to provide a framework for the estimation of product impact during product design. To estimate product impact, models of both the product and society are required. This framework integrates models of the product, scenario, society and impact into an agent-based model to estimate product impact. Although this paper demonstrates the framework using only social impact, the framework can also be applied to economic or environmental impacts individually or all three concurrently. Agent-based modelling has been used previously for product adoption models, but it has not been extended to estimate product impact. Having tools for impact estimation allows for optimising the product design parameters to increase the potential positive impact and reduce potential negative impact. 

Social Impact has been widely discussed by the engineering community, but studies show that there is currently little systematic consideration of the social impact of products in both academia and in industry beyond social impacts on health and safety. This paper illustrates how Failure Mode and Effect Analaysis (FMEA) style analysis can be applied to evaluating the social impact of products. The authors propose a new method titled Social Impact Effects Analysis (SIEA), describe how it is performed, and explain the benefits of performing SIEA.

 

Abstract Researchers have been extensively studying wide-bandgap (WBG) semiconductor materials such as gallium nitride (GaN) with an aim to accomplish an improvement in size, weight, and power of power electronics beyond current devices based on silicon (Si). However, the increased operating power densities and reduced areal footprints of WBG device technologies result in significant levels of self-heating that can ultimately restrict device operation through performance degradation, reliability issues, and failure. Typically, self-heating in WBG devices is studied using a single measurement technique while operating the device under steady-state direct current measurement conditions. However, for switching applications, this steady-state thermal characterization may lose significance since the high power dissipation occurs during fast transient switching events. Therefore, it can be useful to probe the WBG devices under transient measurement conditions in order to better understand the thermal dynamics of these systems in practical applications. In this work, the transient thermal dynamics of an AlGaN/GaN high electron mobility transistor (HEMT) were studied using thermoreflectance thermal imaging and Raman thermometry. Also, the proper use of iterative pulsed measurement schemes such as thermoreflectance thermal imaging to determine the steady-state operating temperature of devices is discussed. These studies are followed with subsequent transient thermal characterization to accurately probe the self-heating from steady-state down to submicrosecond pulse conditions using both thermoreflectance thermal imaging and Raman thermometry with temporal resolutions down to 15 ns. 

Here we report a systematic research on effects of Fe and Cu upon properties relevant for the magnetic shape memory effect of Ni–Mn–Ga ferromagnetic shape memory alloys. Fe and Cu were identified as elements with potential synergism to increase the martensite transformation temperature of Ni–Mn–Ga magnetic shape memory (MSM) alloys. Eighteen Ni–Mn–Ga–Fe–Cu alloys with different systematic trends in substituting the ternary elements with Cu and Fe have been investigated. We found a method to describe the effectiveness of Ni, Mn, and Cu upon raising the martensitic transformation temperature, lowering the saturation magnetization, and varying the Curie temperature. We find the martensite transformation temperature most influenced by the Ni content, followed by Mn, with a smaller effect of Cu. The saturation magnetization decreases with similar coefficients for Mn and Cu alloying. The Curie temperature monotonously decreases with Mn, but not Cu. The 10M martensite structure is stable for the composition Ni46.5Mn25?XGa25-X-YFe3.5CuY with X and Y range of 0–5.7, and 0.8–3.0. Used in combination with the total e/a, the elemental e/a-ratio gives some insight into the complex behavior of quinary MSM alloys and is a useful method of analyzing MSM alloys for improved functional properties.