Fault detection in configurable switched-capacitor filters using transient analysis and dynamic time warping

In this work, we address a low-cost test of switched capacitors filters embedded in configurable analog sections. The proposal improves the Transient Analysis Method (TRAM) by incorporating a similarity measure, dynamic time warping. In this way, we extend TRAM to cases that that initially were not compatible and simplify the test of filters of order higher than two. This paper performs the test evaluation by developing a new simulation model of the addressed system that supports fault injection and simulation. A comparison with experimental data in both normal and faulty behavior validates the model. We consider catastrophic faults in the switches (stuck at open and short) and capacitors (shorts and opens), and deviation faults in the capacitors. The fault simulation results validate the test proposed here.

     

Payload‐centric autonomy for in‐space robotic assembly of modular space structures

The paper addresses the problem of constructing large space structures (～100 m) by using autonomous robots to assemble modular components in space. We are motivated by the problem of creating space structures at a scale greater than what is feasible with a single self‐deploying design. We had two goals in this work. The first was to investigate and demonstrate the feasibility of long‐order multitask autonomy. The second was to study the balance between required tolerances in hardware design and robotic autonomy. This paper reports on a payload‐centric autonomy paradigm and presents results from laboratory demonstrations of automated assembly of structures using a multilimbed robotic platform. We present results with deployable 20 lb payloads (1 m trusses) that are robotically assembled to form a 3‐m diameter kinematically closed loop structure to subcentimeter accuracy. The robot uses its limbs to deploy the stowed modular structural components, manipulate them in free space, and assemble them via dual‐arm force control. We report on results and lessons learned from multiple successful end‐to‐end in‐lab demonstrations of autonomous truss assembly with JPL's RoboSimian robot originally developed for the Defense Advanced Research Projects Agency (DARPA). Videos of these demonstrations can be seen at https://goo.gl/muNLJp (JPL, 2017 ). Each end‐to‐end run took precisely 26 min to execute with very little variance across runs. We present changes/improvements to the RoboSimian system post‐DARPA Robotics Challenge (DRC) (Karumanchi et al., 2016 ). The new architecture has been improved with a focus on scalable autonomy as opposed to semiautonomy as required at the DRC.     

Application of the Fuzzy Logic for the Development of Automnomous Robot with Obstacles Deviation

International Journal of Control, Automation and Systems - This paper proposed to elaborate a navigation system for an autonomous mobile robot, able to deviate from obstacles, from the study and...     

Sparse high‐degree polynomials for wide‐angle lenses

Rendering with accurate camera models greatly increases realism and improves the match of synthetic imagery to real‐life footage. Photographic lenses can be simulated by ray tracing, but the performance depends on the complexity of the lens system, and some operations required for modern algorithms, such as deterministic connections, can be difficult to achieve. We generalise the approach of polynomial optics, i.e. expressing the light field transformation from the sensor to the outer pupil using a polynomial, to work with extreme wide angle (fisheye) lenses and aspherical elements. We also show how sparse polynomials can be constructed from the large space of high‐degree terms (we tested up to degree 15). We achieve this using a variant of orthogonal matching pursuit instead of a Taylor series when computing the polynomials. We show two applications: photorealistic rendering using Monte Carlo methods, where we introduce a new aperture sampling technique that is suitable for light tracing, and an interactive preview method suitable for rendering with deep images.     

Biomaterial Based Polyurethane Adhesive for Bonding Rubber and Wood Joints

An intermediate compound for synthesizing polyester polyol was prepared from glycosylation of potato starch by reacting it with ethylene glycol in presence of sulphuric acid. Glycol glycoside thus prepared was characterized by HPLC and FTIR. This polyhydroxy compound was replaced in varying amounts with trimethylolpropane for polyester polyol synthesis. Sebacic acid was used as dicarboxylic acid along with castor oil for polyester polyol formulation. Polyols were reacted with toluene 2,4-diisocyanate adduct for polyurethane formation. Polyester polyol and polyurethane were characterized by FTIR. Polyurethane was utilized for bonding wood as well as rubber joints. Bond strength was measured by means of lap shear strength and peel strength for wood and rubber joints, respectively. Chemical resistance of polyurethane adhesive was also evaluated. This revised version was published online in July 2006 with corrections to the Cover Date.     

Being Where Our Faculty Are: Emerging Technology Use and Faculty Information-Seeking Workflows

Academic libraries frequently consider students’ high usage of certain technologies when deciding what services to offer electronically, but less research has been done on whether faculty also use any of these technologies. This study surveyed faculty at two very different institutions, a liberal arts college and a Research I university, about the technologies they use or might consider using, with a particular focus on information and/or communication-related technologies. The results show that faculty do use many of the technologies that previous studies have associated with students.     

Application of stochastic system identification to the study of the compliance of electroactive polymers

Electroactive polymers have shown promising applications as transducers that can mimic biological muscle. The modulus or the compliance of many of these devices can change significantly as they are actuated making these materials attractive for applications that require tunable stiffness. We have developed a dynamic mechanical analyzer that is capable of making in situ measurements of the dynamic compliance transfer function of conducting polymers as a function of an electrochemical stimulus. We do this by simultaneously applying a stochastic stress waveform over a potential waveform and calculating the compliance as it changes over the course of electrochemical excitation. Using these signals we can calculate the compliance transfer function between 0.1 and 100 Hz and the impulse response function with up to 3% variation in its parameters. These functions are then computed as charge is injected into the polymer and it is shown that the low frequency gain of the transfer function can change by 30%-40% in the electrochemical system tested.     

Zeitliche und räumliche Skalen der Fluss-Grundwasser-Interaktion: Ein multidimensionaler hydrogeologischer Untersuchungsansatz

River-groundwater interactions show strong scale-dependencies and are often strongly transient. In this regard, small-scale flow conditions in the hyporheic zone at the interface between surface- and groundwater can be important for process-understanding. This especially includes questions concerning flow conditions in salmonid redds of gravel-bed rivers. The Swiss subalpine river Enziwigger was chosen as an example for a small channelized river with artificial steps within the riverbed. Several methods were developed, tested and combined that capture the four dimensions (three spatial and one temporal) of the interactions between surface water, the hyporheic zone and groundwater, for individual river segments. The setup of a monitoring network as well as the realization of field-measurements provided data for groundwater flow models. Continuous time series of hydraulic data, temperature and electrical conductivity within the river and the riverbed, as well as within the riverine groundwater, allowed identifying zones with significant exchange of surface water and groundwater. Additionally, the data helped describe the transient character of groundwater flow-paths under various hydrological boundary conditions. Results of the field-measurements in combination with transient groundwater flow modeling and scenario analyses illustrate the relevance of dynamically changing infiltration and exfiltration patterns within the riverbed.     

Constructal design associated with genetic algorithm to minimize the maximum deflection of thin stiffened steel plates

This paper deals with the application of stochastic technique allied to the constructal design (CD) method and computational modeling for the optimization of composed plates reinforced by stiffeners. More specifically, it seeks to determine the optimal geometric configuration of the stiffened plate that minimizes its maximum deflection. For this purpose, a simply supported rectangular plate (with no stiffeners) was adopted as a reference. Then, a set of geometric configurations was proposed, through the application of CD method, by transforming a volume fraction (ϕ) of the reference plate into longitudinal and transverse stiffeners, maintaining the total volume, in-plane dimensions, boundary conditions, and loading. Regarding the optimization procedure, the genetic algorithm (GA) was chosen as the optimization method, and the geometric parameters considered as degrees of freedom were as follows: the number of longitudinal (N_ls) and transverse (N_ts) stiffeners; the thickness of the longitudinal (t_ls) and transverse (t_ts) stiffeners; and longitudinal and transverse stiffeners' heights ratio (h_ts/h_ls). Moreover, several values of ϕ were considered. Results indicated a great influence of the geometry on the mechanical behavior of the stiffened plates, as the optimal geometric configuration obtained here led to a reduction of over 98% in the maximum deflection in comparison with the reference plate.     

Exploring characteristics and transformational capabilities of InsurTech innovations to understand insurance value creation in a digital world

Recent developments in the insurance industry embrace various “Insurance Technology” (InsurTech) innovations. To date, there is a lack of structured assessments of InsurTech. Prior research on FinTech fails (1) to clarify how InsurTech can be characterized and what capabilities are employed, and hence, (2) to reveal implications for value creation on firm and industry level. We address this by inductively building a model of InsurTech innovation adopting the grounded theory method. Our empirical data includes 208 InsurTech innovations from a market analysis based on Twitter data and a multiple-case study. The resulting model comprises 52 characteristics and 14 transformational capabilities and is integrated with extant value networks and intermediation literature. The former explains how InsurTech affects firm-level value creation and suggests that disruptive potentials emerge from aligning the transformational capabilities along three interdependent activities. The latter explains the entrance of digital intermediaries and their roles in the personal insurance market.