Observation of Microslip Dynamics at High-Speed Microcontacts

The high-speed tribological properties of microscale contacts are studied using an indenter probe and quartz crystal microbalance. Elastic and dissipative shear forces are monitored as a function of contact radius for sapphire/gold interfaces with an adsorbed octadecanethiol monolayer. We observe shear force transitions understood as taking the interface from slipping to stuck conditions. We relate this behavior to the presence of interfacial microslip. Dynamic modeling shows that our observations are consistent with an interface that, when sliding, experiences full slip during half of each cycle. We discuss the implications for this technique as a sensitive probe of sliding friction

Remote Characterization of Dominant Wavelengths From Surface Folding on Lava Flows Using Lidar and Discrete Fourier Transform Analyses

Surface folding is common in lava flows of all compositions and is believed to be due to changes in viscosity and flow velocity between the cooling crust and the more fluid flow interior. However, our understanding of the relationship between surface folding and flow rheology is incomplete. In this study we analyze digital terrain models of eight lava flows ranging in composition from basaltic andesite to rhyolite using a discrete Fourier transform analysis to quantitatively determine dominant surface fold wavelengths. Our discrete Fourier transform analyses show that each lava flow has multiple fold generations and that dominant wavelengths are more closely related to calculated effective viscosity than to lava composition. At our Oregon sites, average dominant wavelengths generally increase with viscosity (r2=0.68), and the correlation improves (r2=0.87) when expanded by including previously measured fold wavelengths and viscosities from the global database. However, there are a few exceptions to this positive trend where a few lava flows have lower or higher than expected dominant fold wavelengths, which we infer are due to secondary factors such as differences in eruption conditions (eruption rate, temperature, etc.). Additionally, over a 5 order of magnitude range in viscosity, there is significant overlap between the ranges of fold wavelengths, particularly from 10 to 20m, for lavas from basaltic andesite to rhyolite, making it difficult to determine a numeric correlation between surface folds and lava rheology that would allow remote characterization of lava

Effects of Landslides on Terrestrial Carbon Stocks With a Coupled Geomorphic-Biologic Model: Southeast Alaska, United States

Landslides influence the global carbon (C) cycle by facilitating transfer of terrestrial C in biomass and soils to offshore depocenters and redistributing C within the landscape, affecting the terrestrial C reservoir itself. How landslides affect terrestrial C stocks is rarely quantified, so we derive a model that couples stochastic landslides with terrestrial C dynamics, calibrated to temperate rainforests in southeast Alaska, United States. Modeled landslides episodically transfer C from scars to deposits and destroy living biomass. After a landslide, total C stocks on the scar recover, while those on the deposit either increase (in the case of living biomass) or decrease while remaining higher than if no landslide had occurred (in the case of dead biomass and soil C). Specifically, modeling landslides in a 29.9 km 2 watershed at the observed rate of 0.004 landslides km −2 yr −1 decreases average living biomass C density by 0.9 tC ha −1 (a relative amount of 0.4%), increases dead biomass C by 0.3 tC ha −1 (0.6%), and increases soil C by 3.4 tC ha −1 (0.8%) relative to a base case with no landslides. The net effect is a small increase in total terrestrial C stocks of 2.8 tC ha −1 (0.4%). The size of this boost increases with landslide frequency, reaching 6.5% at a frequency of 0.1 landslides km −2 yr −1. If similar dynamics occur in other landslide-prone regions of the globe, landslides should be a net C sink and a natural buffer against increasing atmospheric CO2 levels, which are forecast to increase landslide-triggering precipitation events

A model-based approach for automatic validation of protection settings

The reliable operation of protection systems depends on the correct setting of protective devices. Due to the increasing network complexity and the large number of protective devices (and their associated setting parameters), it is extremely laborious for engineers to manually validate the settings. Existing model-based (MB) systems that are capable of performing the validation task require significant manual input for network models creation, relay models configuration, simulation result analysis, etc., which is both time consuming and subject to human errors. This paper presents a methodology that adopts the principle of model-based reasoning (MBR) for automated validation of protection settings. Such a methodology is demonstrated through the design and implementation of a prototype tool Model-Based protection setting Smart Tool (MBST), which is capable of automatically populating network models, configuring relay models with settings to be validated, creating credible system events, and simulating the relays’ behaviour under these events. The automated process is achieved by an interface layer within MBST that allows interaction with a commercially available simulation engine to leverage its internal data and functions for the settings validation task. The simulated results are automatically analysed using a rule-based (RB) approach. The key advantage of the work is the mechanism to automate the entire settings validation process. The design of the interface layer to interact with existing simulation engine and models also demonstrates a solution for rapid prototyping of intelligent systems dedicated to validation of protection settings

German Curriculum Map 2013-2014

This map displays degree requirements, courses, faculty information, clubs & organizations, and Library resources associated with German across the seven Claremont Colleges (7Cs) for the 2013-14 academic year. It was compiled using public information drawn from Colleges websites, course schedules and catalogs, and the Claremont Colleges Library website. This project was completed as part of an IMLS Sparks! Ignition grant in 2013-14

Classics Curriculum Map 2013-2014

This map displays degree requirements, courses, faculty information, clubs & organizations, and Library resources associated with Classics across the seven Claremont Colleges (7Cs) for the 2013-14 academic year. It was compiled using public information drawn from Colleges websites, course schedules and catalogs, and the Claremont Colleges Library website. This project was completed as part of an IMLS Sparks! Ignition grant in 2013-14

Middle East Studies Curriculum Map 2013-2014

This map displays degree requirements, courses, faculty information, clubs & organizations, and Library resources associated with Middle East studies across the seven Claremont Colleges (7Cs) for the 2013-14 academic year. It was compiled using public information drawn from Colleges websites, course schedules and catalogs, and the Claremont Colleges Library website. This project was completed as part of an IMLS Sparks! Ignition grant in 2013-14

Philosophy Curriculum Map 2013-2014

This map displays degree requirements, courses, faculty information, clubs & organizations, and Library resources associated with philosophy across the seven Claremont Colleges (7Cs) for the 2013-14 academic year. It was compiled using public information drawn from Colleges websites, course schedules and catalogs, and the Claremont Colleges Library website. This project was completed as part of an IMLS Sparks! Ignition grant in 2013-14

Enabling efficient engineering processes and automated analysis for power protection systems

The reliable operation of power networks depends on the correct configuration of protection systems. These systems involve the coordination of devices across a wide area, each with numerous setting parameters. Presently, protection settings data are typically stored in various vendor-specific proprietary formats, which are difficult to access, interchange, and manipulate automatically. Consequently, the engineering processes for implementing modern protection systems are extremely complex, involving multiple software tools from different vendors. This paper presents a novel solution to these challenges, through the use of the data model provided by the IEC 61850 standard, with the System Configuration description Language (SCL) format to represent protection settings data. The design of a Protection Setting data Conversion Tool (PSCT) that can automatically convert existing settings data between proprietary formats and the SCL-based format is presented. A case study of its implementation demonstrates the benefits of the common representation of protection settings for network operators and other stakeholders. The paper also addresses the challenges that network operators face in migrating to the new approach from existing legacy protection devices and data formats. Adoption of these recommendations and design approaches would shift protection systems from being largely single-vendor solutions to becoming efficient and truly open platforms, capable of supporting future intelligent applications and tools such as automated protection settings validation, diagnostics, and system simulation

Transient Reactivation of a Deep-Seated Landslide by Undrained Loading Captured With Repeat Airborne and Terrestrial Lidar

Landslides reactivate due to external environmental forcing or internal mass redistribution, but the process is rarely documented quantitatively. We capture the three-dimensional, 1-m resolution surface deformation field of a transiently reactivated landslide with image correlation of repeat airborne lidar. Undrained loading by two debris flows in the landslide’s head, rather than external forcing, triggered reactivation. After that loading, the lower 2 km of the landslide advanced by up to 14 m in 2 years before completely stopping. The displacement field over those 2 years implies that the slip surface gained 1 kPa of shear strength, which was likely accomplished by a negative dilatancy-pore pressure feedback as material deformed around basal roughness elements. Thus, landslide motion can be decoupled from external environmental forcing in cases, motivating the need to better understand internal perturbations to the stress field to predict hazards and sediment fluxes as landscapes evolve