A novel Reverse Electrodialysis application to generate power from low-grade heat

A novel idea for the conversion of low-temperature heat into electricity is based on the generation of electricity from salinity gradients using a Reverse Electrodialysis (RED) device in a closed-loop system. In this concept a limited amount of artificial saline solutions can be used as the working fluids in a closed-loop. The solutions exiting from the RED unit are then regenerated, in order to restore the original salinity gradient, by means of a separation step, which uses low-temperature heat (40-100°C) as its energy source. A theoretical analysis of potentials of this technology is illustrated in the present work

Reactive crystallisation process for magnesium recovery from concentrated brines

Seawater brines, generated either by natural or anthropic processes, often cause significant environmental issues related to their disposal. A clear example is the case of brines from desalination plants, which can have severe environmental impacts on the receiving water body. On the other side, brines can represent a rich and appealing source of raw materials, especially when they are very concentrated, as it happens with bitterns (i.e. exhausted brines) produced in saltworks. In particular, magnesium concentration can reach values up to 30-40 kg/m3 of brine, which is 20-30 times that of typical seawater. An experimental campaign has been carried out in the present work for assessing the potentials for magnesium recovery from concentrated brines. Real brines were collected from the final basins of the saltworks operating in the district of Trapani (Sicily - Italy). Experiments were performed both in a semi-batch and in a continuous 5 litre crystalliser operating by a reactive precipitation process. NaOH solutions were adopted as standard alkaline reactant in order to assess the influence of all operating parameters and reactor configuration on the recovery efficiency and purity of the Mg(OH)2 powder produced. Results have highlighted a very promising strategy for the recovery of Mg from concentrated brines, which could be scaled-up and applied to a number of different scenarios, including existing saltworks and newly designed integrated cycles for Zero Liquid Discharge desalination

Design of Evaporation Ponds for the Fractionated Crystallization of Minerals from Desalination Brines

The evaporative crystallization of minerals in saltworks is one of the oldest industrial processes still in operation and has the potential to achieve high solar energy conversion efficiencies. While salt production from seawater has been extensively studied, the circular economy of brines exploitation is opening new fields of investigation. This article focuses on the design and simulation of a process for selective precipitation and mineral recovery from reverse osmosis brines. The process involves a two-step evaporative system followed by reactive crystallization of magnesium hydroxide. Laboratory tests and simulations using PHREEQC (pH-REdox-Equilibrium C-program) were conducted to validate the thermodynamics of the process and forecast the optimal operative conditions

Twenty-three unsolved problems in hydrology (UPH) – a community perspective

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through on-line media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focussed on process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come

Greta: An interactive expressive ECA system

We have developed a general purpose use and modular architecture of an Embodied Conversational Agent (ECA) called Greta. Our 3D agent is able to communicate using verbal and nonverbal channels like gaze, head and torso movements, facial expressions and gestures. It follows the SAIBA framework [10] and the MPEG4 [6] standards. Our system is optimized to be used in interactive applications. Copyright \ua9 2009, International Foundation for Autonomous Agents and Multiagent Systems

Greta: An interactive expressive ECA system

We have developed a general purpose use and modular architecture of an Embodied Conversational Agent (ECA) called Greta. Our 3D agent is able to communicate using verbal and nonverbal channels like gaze, head and torso movements, facial expressions and gestures. It follows the SAIBA framework [10] and the MPEG4 [6] standards. Our system is optimized to be used in interactive applications. Copyright © 2009, International Foundation for Autonomous Agents and Multiagent Systems

An expressive ECA showing complex emotions

Embodied Conversational Agents (ECAs) are a new paradigm of computer interface with a human-like aspect that allow users to interact with the machine through natural speech, gestures, facial expressions, and gaze. In this paper we present an head animation system for our ECA Greta and we focus on two of its aspects: the expressivity of movement and the computation of complex facial expressions. The system synchronises the nonverbal behaviours of the agent with the verbal stream of her speech; moreover it allows us to qualitatively modify the animation of the agent, that is to add expressivity to the agent's movements. Our model of facial expressions embeds not only the expressions of the set of basic emotions (e.g., anger, sadness, fear) but also different types of complex expressions like fake, inhibited, and masked expressions

An expressive ECA showing complex emotions

Embodied Conversational Agents (ECAs) are a new paradigm of computer interface with a human-like aspect that allow users to interact with the machine through natural speech, gestures, facial expressions, and gaze. In this paper we present an head animation system for our ECA Greta and we focus on two of its aspects: the expressivity of movement and the computation of complex facial expressions. The system synchronises the nonverbal behaviours of the agent with the verbal stream of her speech; moreover it allows us to qualitatively modify the animation of the agent, that is to add expressivity to the agent's movements. Our model of facial expressions embeds not only the expressions of the set of basic emotions (e.g., anger, sadness, fear) but also different types of complex expressions like fake, inhibited, and masked expressions