Using role-based control to produce locomotion in chain-type self-reconfigurable robots

This paper presents a role-based approach to the problem of controlling locomotion of chain-type self-reconfigurable robots. In role-based control, all modules are controlled by identical controllers. Each controller consists of several playable roles and a role-selection mechanism. A role represents the motion of a module and how it synchronizes with connected modules. A controller selects which role to play depending on the local configuration of the module and the roles being played by connected modules. We use role-based control to implement a sidewinder and a caterpillar gait in the CONRO self-reconfigurable robot. The robot is made from up to nine modules connected in a chain. We show that the locomotion speed of the caterpillar gait is constant even with loss of 75% of the communication signals. Furthermore, we show that the speed of the caterpillar gait decreases gracefully with a decreased number of modules. We also implement a quadruped gait and show that without changing the controller the robot can be extended with an extra pair of legs and produce a hexapod gait. Based on these experiments, we conclude that role-based control is robust to signal loss, scales with an increased number of modules, and is a simple approach to the control of locomotion of chain-type self-reconfigurable robots.     

From the Politics of Urgency to the Governance of Preparedness: A Research Agenda on Urban Vulnerability

To date, little social science understanding has been developed about what it would mean to strategically build resilience in the context of such rich interdependencies between social, technical and natural worlds. We argue that shifts in strategies to deal with urban crises marks a turn from the politics of urgency, characteristic of crisis management, towards a governance of preparedness, characterised by strategies to build urban resilience. Social science needs to develop research agendas that critically engage with different understandings of resilience and the challenges of building resilience across different scales of urban governance.     

Parallel architectures for AI semantic network processing

Artificial intelligence (AI) applications are growing in several fields, and in many such applications knowledge bases must be manipulated. This activity is usually performed by an external agent such as a central processor, but often this cannot supply the speed required. Knowledge-oriented architectures provide an efficient execution of knowledge manipulations. This paper provides an introduction to a particular subset of knowledge-oriented architectures, the semantic network approach, which is one of the most commonly used methods of representing and manipulating knowledge in the AI field. A brief overview of the semantic network components is presented in order to provide a background to the topic. The purpose of this paper is to review the proposed, implemented and/or simulated architectures for semantic network processing, and to discuss the capabilities and limitations of such architectures.     

Performance analysis of zinc—bromine batteries in vehicle and utility applications

Rechargeable zinc—bromine batteries exhibit a number of inherent advantages that let them appear as possible candidates for applications in electric vehicles and utility load levelling. Based upon known single cell data, the performance characteristics of zinc—bromine batteries in vehicle and utility applications are predicted. The attainable specific energy and energy efficiency are computed as a function of specific power. The effects of specific cell resistance, self-discharge rate, and charge and discharge time on specific energy and efficiency are examined.     

Steps Toward Engineering Unity

The last century has witnessed the organization of professional societies in all fields of science and engineering. The consolidation of these societies into a unity such as the American Medical Association has been the aim of leaders in technology for many years. The following paper summarizes the actions taken and the plans proposed toward this much needed goal.     

Der Ungleichförmigkeitsgrad von dieselelektrischen Aggregaten bei Berücksichtigung der Wellenelastizität

Ohne Zusammenfassung Mitteilung aus dem lehrsluhl für Verfahrenslechnik der Technischen Hochschule München Schlu? des Aufsatzes aus Heft 5 (1956) S. 167/77.     

Influence of fires on O3 concentrations in the western U.S

Because forest fires emit substantial NOx and hydrocarbons--known contributors to O3 production--we hypothesize that interannual variation in western U.S. O3 is related to the burned area. To evaluate this hypothesis we used a gridded database of western U.S. summer burned area (BA) and biomass consumed (BC) by fires between 101-125 degrees W. The fire data were compared with daytime summer O3 mixing ratios from nine rural Clean Air Status and Trends Network (CASTNET) and National Park Service (NPS) sites. Large fire years exhibited widespread enhanced O3. The summer BA was significantly correlated with O3 at all sites. For each 1 million acres burned in the western U.S. during summer, we estimate that the daytime mean O3 was enhanced across the region by 2.0 ppbv. For mean and maximum fire years, O3 was enhanced by an average of 3.5 and 8.8 ppbv, respectively. At most sites O3 was significantly correlated with fires in the surrounding 5 x 5 degrees and 10 x 10 degrees regions, but not with fires in the nearest 1 x 1 degree region, reflecting the balance between O3 production and destruction in a high NOx environment. BC was a slightly better predictor of O3, compared with BA. The relationship between O3 and temperature was examined at two sites (Yellowstone and Rocky Mountain National Parks). At these two sites, high fire years were significantly warmer than lowfire years; however, daytime seasonal meantemperature and O3 were not significantly correlated. This indicates that the presence of fire is a more important predictor for O3 than is temperature.