Fast Scheduling of Robot Teams Performing Tasks With Temporospatial Constraints

The application of robotics to traditionally manual manufacturing processes requires careful coordination between human and robotic agents in order to support safe and efficient coordinated work. Tasks must be allocated to agents and sequenced according to temporal and spatial constraints. Also, systems must be capable of responding on-the-fly to disturbances and people working in close physical proximity to robots. In this paper, we present a centralized algorithm, named 'Tercio,' that handles tightly intercoupled temporal and spatial constraints. Our key innovation is a fast, satisficing multi-agent task sequencer inspired by real-time processor scheduling techniques and adapted to leverage a hierarchical problem structure. We use this sequencer in conjunction with a mixed-integer linear program solver and empirically demonstrate the ability to generate near-optimal schedules for real-world problems an order of magnitude larger than those reported in prior art. Finally, we demonstrate the use of our algorithm in a multirobot hardware testbed

INTERESTS AND OPTIONS OF DEVELOPING AND LEAST-DEVELOPED COUNTRIES IN A NEW ROUND OF MULTILATERAL TRADE NEGOTIATIONS

Negotiating interests and options have to be identified against the background of the possible agenda of a new round. Several important elements of this agenda are codified in what is referred to as the "built-in agenda", including: (i) an assessment of the implementation of Uruguay Round Agreements (RAS); (ii) specific reviews of particular agreements that were mandated by the Uruguay Round; and, as the core of a new round, (iii) new negotiations on agriculture, GATS, and Trips. Possible further components of the agenda could be negotiations on trade and investment, competition policy, trade facilitation, transparency in government procurement, environmental and labour standards, and further liberalization of industrial tariffs, and textiles and clothing. Many developing and least-developed countries are reluctant to support such a comprehensive agenda, because they are still pre-occupied with difficult administrative, institutional and financial problems arising from the implementation of various RAS. They also have difficulties in articulating the strategies that could underpin the identification of their negotiating interests and options. Their preparation for a new round is likely to be mostly inadequate owing to a lack of human knowledge and institutional capacity that an effective participation in the WTO process requires. They will thus have to take decisions on complex issues that they may not have adequately analyzed and understood. But a new trade round will also present an important opportunity for developing countries to press for enhanced market access and to undo some of the damages imposed by the RAS dealing with rules and standards. They have taken on many mandatory obligations in exchange for non-binding and "best endeavour" concessions from the developed countries. Rebalancing this situation should be a major concern for both the developing and the least-developed countries. The new round should also offer the low-income countries an opportunity to be more pro-active in terms of defining its agenda, for instance in proposing multilaterally negotiated decisions regarding the criteria for categorizing WTO member countries, as well as the form and context of "special and differential treatment" for the developing and least-developed countries. This paper discusses the trade-strategy options of low-income countries, the areas of greatest interest to developing countries, as well as those that are to pose the greatest difficulties, the question of how developing countries can enhance the effectiveness of their participation in the new Round of Multilateral Trade Negotiations, and also makes some suggestions on how to change WTO governance and management structures in order to ensure that the concerns of flow-income members are given greater prominence in the organization´s activities.

Reinforcement learning for zone based multiagent pathfinding under uncertainty

Ministry of Education, Singapore under its Academic Research Funding Tier

Texas Register

A weekly publication, the Texas Register serves as the journal of state agency rulemaking for Texas. Information published in the Texas Register includes proposed, adopted, withdrawn and emergency rule actions, notices of state agency review of agency rules, governor's appointments, attorney general opinions, and miscellaneous documents such as requests for proposals. After adoption, these rulemaking actions are codified into the Texas Administrative Code

Multi-agent based architecture for digital libraries

Digital Libraries (DL) generally contain a collection of independently maintained data sets, in different formats, which may be queried by geographically dispersed users. The general problem of managing such large digital data archives is particularly challenging when the system must cope with data which is processed on demand. This dissertation proposes a Multi-Agent System (MAS) architecture for the utilisation of an active DL that provides computing services in addition to data-retrieval services, so that users can initiate computing jobs on remote supercomputers for processing, mining, and filtering of the data in the library. The system architecture is based on a collaborative set of agents, where each agent undertakes a pre-defined role, and is responsible for offering a particular type of service. The integration of services is based on a user defined query which can range in complexity from simple queries, to specialised algorithms which are transmitted to image processing archives as mobile agents. The proposed architecture enables new information sources and services to be integrated into the system dynamically, supports autonomous and dynamic on-demand data processing based on collaboration between agents, capable of handling a large number of concurrent users. Focus is based on the management of mobile agents which roam through the servers that constitute the DL to serve user queries. A new load balancing scheme is proposed for managing agent load among the available servers, based on the system state information and predictions about lifetime of agent tasks and server status. The system architecture is further extended by defining a gateway to provide interoperability with other heterogeneous agent-based systems. Interoperability in this sense enables agents from different types of platforms to communicate between themselves and use services provided by other systems. The novelty of the proposed gateway approach lies in the ability to adapt an existing legacy system for use with the agent-based approach (and one that adheres to FIPA standards). A prototype has been developed as a proof-of-concept to outline the principles and ideas involved, with reference to the Synthetic Aperture Radar Atlas (SARA) DL composed of multi-spectral remote-sensing imagery of the Earth. Although, the work presented in this dissertation has been evaluated in the context of SARA DL, the proposed techniques suggest useful guidelines that may be employed by other active archival systems

Combustion in microspaces and its applications

PhD research can be divided in three main parts: part one and two related to the development of some of the most important aspects of the catalytic combustion in microspaces, part three related to a possible application of the catalytic combustion in microspaces. Part 1: The combustion of gaseous HC fuels in a small confined space could represent an alternative way to produce thermal and electrical energy. The combustion of CH4 and its lean mixtures with H2 on catalytic monoliths was studied and optimized. 2% Pd/(5% NiCrO4), 2% Pd/(5% CeO2ZrO2), 2% Pd/(5% LaMnO3ZrO2) and 2% Pt/(5% Al2O3) catalysts, suitably developed, were deposited on SiC monoliths via in situ SCS and tested in a lab-scale microreactor by feeding only CH4, only H2, and three lean CH4/H2 mixtures with increased content of H2 and constant thermal power density of 7.6 MWth m-3. Monolith with 2% Pt/(5% Al2O3) was very appropriate for the combustion of only CH4 or H2, but its performance worsen when H2 was added to the reactive mixture. On the contrary, the Pd-based catalysts were most suitable for the combustion of the CH4/H2 lean mixtures, with the best behavior shown by 2% Pd/(5% NiCrO4) followed by 2% Pd/(5% CeO2ZrO2). Monolith coated with 2% Pd/(5% LaMnO3ZrO2), instead, showed the worse performance, both in terms of CH4 combustion only and of the various mixtures; moreover, it displayed quite high CO emissions, not compatible with the environmental issues. In particular, the catalytic reactivity towards CH4 combustion of the Pd- based raised by increasing the H2 content in the reactive mixture. The observed enhancement in reactivity of the mixture when the CH4 fuel was enriched with H2 could be explained by an increase of the OH• radicals in the gas mixture. Part 2: The present work deals with the investigation on the performance of catalyst 2% Pd/ 5% LaMnO3•ZrO2 (PLZ), lined on silicon carbide (SC, with thermal conductivity of 250 W m-1 K-1) or cordierite (CD, with thermal conductivity of 3 W m-1 K-1) monoliths, for the CH4/H2/air lean mixtures oxidation. The bare and coated monoliths were tested into a lab- microreactor designed to provide a favorable environment for microscale combustion of CH4/H2/air lean mixtures to reach high power density (7.6 MWth m-3; GHSV 16,000 h-1). Various CH4/H2 mixtures were tested in heating and cooling phases on the various monoliths, by studying both the homogenous and heterogeneous reactions. The relative percentages of methane and hydrogen were mutually varied (maintaining the sum of the two fuels equal to 100%), in order to always assure a constant power density. The air was always fed with  equal to 2. The main aim of the catalytic combustion tests was to select the best settings to achieve at the minimum temperature full CH4 conversion with the minimum H2 concentration in the reactive mixture, accompanied by the lowest possible CO concentration. Depending on the thermal conductivity of the tested monoliths, the existence of a steady-state multiplicity was verified, mainly when the hydrogen concentration was quite low. Basically, microburners with low wall thermal conductivity (CD monoliths) exhibited shorter ignition times compared to the higher thermal conductivity ones (SC monoliths) due to the formation of spatially localized hot spots that promoted catalytic ignition. At the same time, the CD material required shorter times to reach steady-state. But SC materials assured longer time on stream operations. The presence of the catalyst lined on both monoliths allowed reaching lower CO emissions. The best results belonged to the catalytic SiC monolith, with a low hydrogen concentration in the fed mixtures. Part 3: The idea was to realize an autothermal steam reforming reaction. This was made by coupling a combustion reaction (exothermic), which provided the heat necessary, with a steam reforming reaction (endothermic) in a same specific built micro reactor. The total reagents chosen for the two reactions were methane (used both as fuel and as a reactant for the steam reforming), air and steam (produced by heating water). The main advantage of this system: producing enough energy, for example, to power auxiliary transportation of vehicles, reducing consumption and pollutant emissions; at the same time, because of the overall limited dimensions, reducing the risk of explosion if compared to the hydrogen "on board " storage. The development was a stainless steel reactor consisting of two plates with microchannels, containing the catalyst (Pt/AlO3), in which the reactions took place. These plates were placed in indirect contact, separated by a middle plate made of stainless steel, so to conduct the heat from the combustion side to the steam reforming, and also to avoid the mixing of the fluids. The sealing of both sides were ensured by two ceramic gaskets, suitable to withstand high temperatures. The sizing was performed first theoretically assuming a S / C = 4 (Steam to Carbon), and taking into account the maximum flow rates that could be set to the mass flow controllers. It was then calculated the theoretical thermal power necessary to sustain the steam reforming process, and then calculated the flow of methane and air to be sent to the combustor, to obtain an autothermal reforming. The catalyst used was chosen because of its catalytic activity for both types of reaction. Once it was determined the best side for the steam reforming, it was decided to experiment the coupled reactions. After having reached 900 °C in oven, with complete methane combustion, oven heat was no more provided: combustion was able to be sustained because of a mixture of 7% CH4 in air (inside the flammability limit) and reagents for the steam reforming were sent in a steam/carbon 4:1 replacing nitrogen flow. Results show how the performance of the reactor was affected by thermal dissipation; hence the material used as insulating, in order to wrap up the reactor, plays a key role for performing tests. Tests were carried out increasing thermal power from combustion side to balance the heat dissipations, so to obtain a balance between heat generated and used by the reaction of steam reforming and the heat lost in the environment. It has been showed the way for producing good quality data on coupling combustion and steam reforming reactions in this reactor. In a future, it could be possible using a GC instead of the ABB analyzer in case of new tests with high CH4 not reacted, or of course improving methane conversion choosing a better catalyst for steam reforming, composing a reactor with multiple plates for optimizing the process as shown in Vlachos' simulations, and trying to run flows in either concurrent or countercurren