How Does Silo Storage Time Affect Pavement Durability in Cold Weather Climates?

One of the most significant problems in asphalt pavements in cold weather climates like New England is thermal cracking. Thermal cracks allow water to penetrate into a pavement, significantly weakening the entire structure which necessitates expensive maintenance and repair. The main goal of this research project was to investigate how heated silo storage time, a process during asphalt production, impacts how likely asphalt pavement is to experience thermal cracking related problems. Asphalt concrete specimens aged for various amounts of time in a storage silo were tested using the Disk-Shaped Compact Tension test, a laboratory test that evaluates asphalt specimens\u27 thermal cracking susceptibility. Although the results were not definitive, the data analysis indicated that silo storage time is having certain negative effects on asphalt’s thermal cracking resistance. Ideally, the results from this research will give transportation agencies and private contractors a better understanding of how production processes impact the performance of asphalt concrete

A Comparison of the Embedding Method to Multi-Parametric Programming, Mixed-Integer Programming, Gradient-Descent, and Hybrid Minimum Principle Based Methods

In recent years, the embedding approach for solving switched optimal control problems has been developed in a series of papers. However, the embedding approach, which advantageously converts the hybrid optimal control problem to a classical nonlinear optimization, has not been extensively compared to alternative solution approaches. The goal of this paper is thus to compare the embedding approach to multi-parametric programming, mixed-integer programming (e.g., CPLEX), and gradient-descent based methods in the context of five recently published examples: a spring-mass system, moving-target tracking for a mobile robot, two-tank filling, DC-DC boost converter, and skid-steered vehicle. A sixth example, an autonomous switched 11-region linear system, is used to compare a hybrid minimum principle method and traditional numerical programming. For a given performance index for each case, cost and solution times are presented. It is shown that there are numerical advantages of the embedding approach: lower performance index cost (except in some instances when autonomous switches are present), generally faster solution time, and convergence to a solution when other methods may fail. In addition, the embedding method requires no ad hoc assumptions (e.g., predetermined mode sequences) or specialized control models. Theoretical advantages of the embedding approach over the other methods are also described: guaranteed existence of a solution under mild conditions, convexity of the embedded hybrid optimization problem (under the customary conditions on the performance index), solvability with traditional techniques (e.g., sequential quadratic programming) avoiding the combinatorial complexity in the number of modes/discrete variables of mixed-integer programming, applicability to affine nonlinear systems, and no need to explicitly assign discrete/mode variables to autonomous switches.Comment: Accepted to IEEE Transactions on Control Systems Technolog

Industrial Policy as Strategic Trade Policy in a Global Economy

With the introduction of “strategic trade policy” in the 1980’s came two separate theoretical justifications for increased government intervention to promote national industries: first, argued by Brander and Spencer (1985), the government could alter the strategic interaction in oligopolistic competition to shift profits to a domestic firm; second, the government could promote key industries in order to capture the benefits of positive externalities, such as knowledge spillovers. But the creation of the WTO and the regulation of export subsidies soon limited the strategic trade policy options available to governments. This paper examines the case for providing R&D and capital subsidies to domestic firms as a kind of strategic trade policy in the increasingly global economy of the 21st century

Smaltimento e recupero di materie prime da batterie al litio

Ogni anno sul mercato Europeo sono immesse 800000 tonnellate di batterie, circa il 25% di queste sono batterie agli ioni di litio. Le caratteristiche delle batterie agli ioni di litio le hanno rese particolarmente adatte per apparecchiature portatili quali, ad esempio, dispositivi di comunicazione e informatici, riproduttori portatili, apparecchiature mediche, dispositivi industriali, applicazioni militari e qualsiasi altro prodotto che richiede una fonte energetica e di alta qualità. Grazie a queste caratteristiche e ad una sempre maggior diffusione di questi dispositivi la divulgazione sui mercati mondiali delle batterie al litio è in continua crescita. Batterie e accumulatori non pongono particolari problemi quando sono in fase di utilizzo o di stoccaggio ma hanno un periodo di vita medio di circa 3 anni;esiste dunque un problema ambientale legato al loro smaltimento. Le batterie al litio contengono infatti materiali tossici, infiammabili ed in parte volatili. I rischi connessi allo smaltimento delle batterie esauste sono dovuti alla diffusione nell’ambiente di tali materiali pericolosi, sia attraverso l’incenerimento,sia attraverso il deposito in discarica. Uno dei problemi per la produzione queste batterie è l’approvvigionamento di litio. Il litio è, infatti, disponibile in natura in quantità limitata e richiede processi di estrazione particolarmente complicati e costosi e il mercato è in mano a pochi produttori. Il recupero delle materie prime da batterie al litio, che verrà poi riutilizzato per la produzione di nuovo materiale catodico, risulta quindi molto vantaggioso sia da un punto di vista economico sia da quello ambientale

Company environmental and societal positions as sources of competitive advantage: Implications for sustainable agriculture producers

Use of an environmental positioning strategy can help small-scale agricultural producers present their products to consumers in a more appealing manner

A general stability criterion for switched linear systems having stable and unstable subsystems

We report conditions on a switching signal that guarantee that solutions of a switched linear systems converge asymptotically to zero. These conditions are apply to continuous, discrete-time and hybrid switched linear systems, both those having stable subsystems and mixtures of stable and unstable subsystems

Indoor Particulate Matter during HOMEChem: Concentrations, Size Distributions, and Exposures.

It is important to improve our understanding of exposure to particulate matter (PM) in residences because of associated health risks. The HOMEChem campaign was conducted to investigate indoor chemistry in a manufactured test house during prescribed everyday activities, such as cooking, cleaning, and opening doors and windows. This paper focuses on measured size distributions of PM (0.001-20 μm), along with estimated exposures and respiratory-tract deposition. Number concentrations were highest for sub-10 nm particles during cooking using a propane-fueled stovetop. During some cooking activities, calculated PM2.5 mass concentrations (assuming a density of 1 g cm-3) exceeded 250 μg m-3, and exposure during the postcooking decay phase exceeded that of the cooking period itself. The modeled PM respiratory deposition for an adult residing in the test house kitchen for 12 h varied from 7 μg on a day with no indoor activities to 68 μg during a simulated day (including breakfast, lunch, and dinner preparation interspersed by cleaning activities) and rose to 149 μg during a simulated Thanksgiving day

Coral reef drag coefficients – water depth dependence

Author Posting. © American Meteorological Society, 2017. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 47 (2017): 1061-1075, doi:10.1175/JPO-D-16-0248.1.A major challenge in modeling the circulation over coral reefs is uncertainty in the drag coefficient because existing estimates span two orders of magnitude. Current and pressure measurements from five coral reefs are used to estimate drag coefficients based on depth-average flow, assuming a balance between the cross-reef pressure gradient and the bottom stress. At two sites wind stress is a significant term in the cross-reef momentum balance and is included in estimating the drag coefficient. For the five coral reef sites and a previous laboratory study, estimated drag coefficients increase as the water depth decreases consistent with open channel flow theory. For example, for a typical coral reef hydrodynamic roughness of 5 cm, observational estimates, and the theory indicate that the drag coefficient decreases from 0.4 in 20 cm of water to 0.005 in 10 m of water. Synthesis of results from the new field observations with estimates from previous field and laboratory studies indicate that coral reef drag coefficients range from 0.2 to 0.005 and hydrodynamic roughnesses generally range from 2 to 8 cm. While coral reef drag coefficients depend on factors such as physical roughness and surface waves, a substantial fraction of the scatter in estimates of coral reef drag coefficients is due to variations in water depth.The Red Sea field program was supported by Awards USA 00002 and KSA 00011 made by KAUST to S. Lentz and J. Churchill. The Palau field program was funded by NSF Award OCE-1220529

Implicit Brushes for Stylized Line-based Rendering

International audienceWe introduce a new technique called Implicit Brushes to render animated 3D scenes with stylized lines in real-time with temporal coherence. An Implicit Brush is defined at a given pixel by the convolution of a brush footprint along a feature skeleton; the skeleton itself is obtained by locating surface features in the pixel neighborhood. Features are identified via image-space fitting techniques that not only extract their location, but also their profile, which permits to distinguish between sharp and smooth features. Profile parameters are then mapped to stylistic parameters such as brush orientation, size or opacity to give rise to a wide range of line-based styles