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Electricity from renewable sources can be procured at the household level in a variety of ways. In addition to the costs and benefits, options may vary based on the effort needed for and duration of procurement. For example, renewable electricity provided by a utility company (i.e., green electricity) can be procured by a phone-call, online form, or mail-in application. In some cases, residents may be automatically enrolled in a greener electricity supply without any effort at all if there is a Community Choice Aggregator (CCA). However, getting rooftop solar PV installed would require an administrative as well as technical process, which needs higher consumer engagement. These differences may influence household choices when comparing procurement options. Therefore, this study focuses on the following research questions: - 1) How does procurement engagement and duration influence perceived utility and willingness to pay for renewable electricity procurement? 2) How does a greener default option (e.g., the CCA model) influence the perceived utility of the default option? 3) What kinds of consumers want more renewable energy than the default option? How does this change when the default option is greener?

As the cost of renewable energy systems has decreased, options for energy procurement have proliferated to meet consumer demand. There are growing concerns regarding how virtual procurement options (such as green electricity subscription programs) influence consumer adoption of physical procurement options (such as rooftop solar PV). Increased options may confuse consumers and increase the likelihood of making sub-optimal choices for achieving their goals. It is much easier for consumers to choose virtual options (by doing nothing or clicking a button), but the costs and benefits that consumers receive vary. For example, will increased virtual options decrease the likelihood of people deciding to install rooftop solar, which have higher potential bill savings? This study addresses this question using a discrete choice experiment where participants will be asked to choose the best electricity source among 3 options. By fitting the resulting survey data using a logit model we aim to answer the following research questions: (1) Which attributes explain preferences towards virtual, physical and combined procurement options? (2) How much are people willing to pay for virtual, physical and combined procurement options?

The research presented in this work addresses open questions regarding (i) the fundamental understanding of powder compaction, and (ii) the complex mechanical response of particle-binder composites under large deformations. This work thus benefits a broad range of industries, from the pharmaceutical industry and its recent efforts on continuous manufacturing of solid tablets, to the defense and energy industries and the recurrent need to predict the performance of energetic materials. Powder compacts and particle-binder composites are essentially confined particulate systems with significant heterogeneity at the meso (particle) scale. While particle mechanics strategies for modeling evolution of mesoscale microstructure during powder compaction depend on the employed contact formulation to accurately predict macroscopic quantities like punch and die wall pressures, modeling of highly nonlinear, strain-path dependent macroscopic response without a distinctive yield surface, typical of particle-binder composites, requires proper constitutive modeling of these complex deformation mechanisms. Moreover, continued loading of particle-binder composites over their operational life may introduce significant undesirable changes to their microstructure and mechanical properties. These challenges are addressed with a combined effort on theoretical, modeling and experimental fronts, namely, (a) novel contact formulations for elasto-plastic particles under high levels of confinement, (b) a multi-scale experimental procedure for assessing changes in microstructure and mechanical behavior of particle-binder composites due to cyclic loading and time-recovery, and (c) a finite strain nonlinear elastic, endochronic plastic constitutive formulation for particle-binder composites.

Smallholder farmers’ responses to the climate-induced agricultural changes are not uniform but rather diverse, as response adaptation strategies are embedded in the heterogonous agronomic, social, economic, and institutional conditions. There is an urgent need to understand the diversity within the farming households, identify the main drivers and understand its relationship with household adaptation strategies. Typology construction provides an efficient method to understand farmer diversity by delineating groups with common characteristics. In the present study, based in the Uttarakhand state of Indian Western Himalayas, five farmer types were identified on the basis of resource endowment and agriculture orientation characteristics. Factor analysis followed by sequential agglomerative hierarchial and K-means clustering was use to delineate farmer types. Examination of adaptation strategies across the identified farmer types revealed that mostly contrasting and type-specific bundle of strategies are adopted by farmers to ensure livelihood security. Our findings show that strategies that incurred high investment, such as infrastructural development, are limited to high resource-endowed farmers. In contrast, the low resourced farmers reported being progressively disengaging with farming as a livelihood option. Our results suggest that the proponents of effective adaptation policies in the Himalayan region need to be cognizant of the nuances within the farming communities to capture the diverse and multiple adaptation needs and constraints of the farming households. © 2019, The Author(s).

Powder compaction is the process of transforming granular media into a solid body with a high relative density (low porosity) and a unique anisotropic microstructure. It is critical to understand the physical mechanisms of the compaction process in order to identify powder properties and optimal process parameters for achieving desired properties of the final product. Tools that can simulate particle rearrangement and deformation during the compaction process are usually developed to guide such fundamental understanding. This study aims at understanding powder compaction using particle mechanics approach. Specifically, it employs the nonlocal contact formulation to predict the contact behavior of a single elastic particle within a confined granular system. As the result of the study, we present a new version of the nanoHUB Powder Compaction simulation tool. This version includes additional modeling features, such as a curvature correction, simulation of the contact radius evolution with particle deformation, and mechanical property extraction from an experimental dataset provided by the user.

Synthetic materials for the reconstruction of bone defects have to fulfill a wide range of requirements: they should be biocompatible and ideally osteoconductive; with adequate mechanical properties if used in loaded bone defects; they also have to be bioresorbable with a degradation characteristic that allows the organism to replace the implant material by fully functional bone in a balanced time schedule. Silicon and zinc modified tricalcium phosphate (Si,Zn-TCP) was synthesized as a candidate for resorbable temporal bone implant having a controlled solution-driven resorption rate (i.e. dissolution rate) and to promote bone formation. Si and Zn effect on dissolution behavior of tricalcium phosphate (TCP) in the simulated body fluid (SBF) has been investigated. Changes in the surface morphologies and phase composition before and after immersion in SBF were studied. The experimental results show that the dissolution rate decreases with the increasing Si and Zn content in TCP, and Zn inhibits HAp reprecipitation from SBF. The cytotoxicity test shows that Si and Zn addition has no cytotoxic behavior on the cell within the employed additive level.

The long term durability of CFRP strengthened steel structures is a key parameter for their safe use and effective design. Strengthened members can be subjected to different environmental conditions and loading scenarios during their service life, the effect of which on the failure mechanism of the strengthened members require fundamental investigations. This research presents experimental and theoretical investigations on the effects of freeze-thaw cycling and wet thermo-mechanical loading on the bond strength and failure mode of steel-CFRP adhesive joints. The influence of these conditions on the mechanical properties of pure epoxy is also investigated to give insight into the structural behaviour and also provide data for the theoretical model. The results show that the freeze-thaw cycling decreases the bond strength of the joint by about 28% and leads to variations in the failure mode. A reduction in the initial elastic modulus of the pure epoxy was also observed. The results of the wet thermo-cyclic exposure combined with sustained loading show that these conditions have little impact on the bonding strength when applied separately. However, when applied simultaneously, the mechanical properties of the epoxy and the bond strength of the joints are significantly reduced with failure observed at less than 30% of the static strength and at the temperature range well below the glass transition temperature of the adhesive. A simple shear stress-slip model is developed to analyse single-lap joints, in which the effects of freeze-thaw and thermal cycling are introduced in terms of reduced elastic modulus of the adhesive. The predicted failure load correlates well with the experimental data. A more accurate high order model is also developed that is combined with fracture mechanics and can account for the shear deformability of the adhesive layer and considers normal interfacial stresses. A new methodology to evaluate the effects of freeze-thaw cycling is proposed, which considers the effect of moisture swelling, thermal expansion and change in material properties. Finally, parametric studies are conducted and the results are presented in terms of bond strength, interfacial stresses and deformations.