Thermodynamics of calcium and oxygen in molten titanium and titanium-aluminum alloy

The deoxidation equilibrium of molten titanium and titanium-aluminum alloys saturated with solid CaO has been measured in the temperature range from 1823 to 2023 K. The equilibrium constant of reaction CaO (s)=Ca (mass pct in Ti,Ti-Al)+O (mass pct in Ti,Ti-Al) and the interaction parameter between calcium and oxygen were determined for Ti, TiAl, and TiAl₃. The standard Gibbs energy of reaction for TiAl was obtained as follows: $$\Delta G^\circ = 279,000 - 103TJ/mol$$ The possibilities for the deoxidation of titanium and titanium-aluminum alloys by using calcium-based fluxes are discussed.     

A control method with pheromone information for a transport system

Since the control methods of a transport system between processing machines are specialized for each layout of the system, it is difficult to design prompt schedules and control logic for new complicated systems, especially in cases of machine faults or restructuring the system to modify the layout. In this article, we describe a multiagent transport control system which utilizes pheromone information. Each element of the system acts as an agent and estimates the appropriate path and time to drive out the products using information obtained by communication with other elements as well as pheromone information deposited on the tracks of the products.     

Fine two-phase routing over shortest paths with traffic matrix

This paper presents an IP finely-distributed load-balanced routing scheme based on two-phase routing over shortest paths, where the traffic matrix is given. It is called the fine two-phase routing (F-TPR) scheme. F-TPR more finely distributes traffic from a source node to intermediate nodes than the original TPR. F-TPR determines the distribution ratios to intermediate nodes for each source–destination node pair independently. To determine an optimum set of distribution ratios, a linear programming (LP) formulation is derived. We compare the F-TPR scheme against the TPR scheme and the sophisticated traffic engineering (TE) scheme of Multi-Protocol Label Switching (MPLS-TE). Numerical results show that F-TPR greatly reduces the network congestion ratio compared to TPR. In addition, F-TPR provides almost the same network congestion ratios as MPLS-TE, the difference is surprisingly less than 0.1% for the various network topologies examined. In addition, considering the practical implementation of F-TPR for routers, we also investigate the case that traffic from a source node to a destination node is not allowed to be split over multiple routes. The non-split problem is formulated as an integer linear programming (ILP) problem. As it is difficult to solve the ILP problem within practical time, two heuristic algorithms are presented: Largest Traffic Demand First (LTDF) and a Random Selection (RS). The applicability of LTDF and RS are presented in terms of network size. We find that non-split F-TPR also matches the routing performance of MPLS-TE within an error of 1%, when network size is large enough.     

Semi-autonomous serially connected multi-crawler robot for search and rescue

In this paper, we develop a semi-autonomous serially connected multi-crawler robot for search and rescue. In large-scale disasters, such as earthquakes and tornadoes, the application of rescue robots to search for survivors under rubble would be beneficial. Snake-like robots (robots composed of serially connected units) are an effective candidate for such robots. Their long body enables them to overcome obstacles, and they can move into narrow spaces because of their thin shape. However, conventional snake-like robots have significant problems with operability. The numerous degrees of freedom of their bodies require complex operation to overcome obstacles, and training is required for the operators. Thus, survivors or community members cannot operate conventional robots to search for victims, despite the availability of such rescue robots. Here, we address this problem and develop a semi-autonomous serially connected multi-crawler robot designed for non-trained operators, such as community members or rescued survivors. It can be controlled easily by a conventional two-channel user interface with levers for turning and straight line motion. To demonstrate the effectiveness of our proposed mechanism, a prototype robot was developed and experiments were conducted. The results confirm that the proposed robot had both higher operability and higher mobility than conventional robots.     

Navigation system for an autonomous robot using an ocellus camera in an indoor environment

Autonomous and mobile robots are being expected to provide various services in human living environments. However, many problems remain to be solved in the development of autonomous robots that can work like humans. When a robot moves, it is important that it be able to have self-localization abilities and recognize obstacles. For a human, the present location can be correctly checked through a comparison between memorized information assuming, it is correct, and the present situation. In addition, the distance to an object and the perception of its size can be estimated by a sense of distance based on memory or experience. Therefore, the environment for robotic activity assumed in this study was a finite-space such as a family room, an office, or a hospital room. Because an accurate estimation of position is important to the success of a robot, we have developed a navigation system with self-localization ability which uses only a CCD camera that can detect whether the robot is moving accurately in a room or corridor. This article describes how this system has been implemented and tested with our developed robot.     

Detection of environmental changes from network structure

We studied the networks of the temperature record in the atmosphere. They are made by the strength of the synchronization, including the delay between temperatures at locations on Earth. We consider these locations as nodes, and we consider a pair of locations as a link if the synchronization between them is stronger than a threshold. The network is scale-free, which is thought to contribute to the stability of the climate. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007     

A counterexample to a proposed dynamic programming algorithm for optimal bid construction in an auction-based fully distributed manufacturing system

The paper by Veeramani and Wang (Int J Adv Manuf Technol 28:541–550, 2006) published in this journal offers a general bid construction scheme for minimizing the job flow time in auction-based manufacturing control and claims the optimality of the procedure. The purpose of this note is to provide a small example, in which their proposed new method fails to produce an optimal solution. We also address efficient correct algorithms so as to protect the readers from mistakenly believing that their new procedure is a better way of computing solutions.     

感应电机无速度传感器矢量控制系统的定子电阻在线辨识

该文针对利用磁通观测器推算转子磁通的感应电机无速度传感器矢量控制系统，提出了定子电阻在线辨识法。在利用q轴磁通推算转速的基础上，该系统利用d轴磁通误差实现定子电阻在线辨识，该方案的优点是系统简单，解决了低速运行时电压模型的定子电阻变化对系统稳定性和速度控制精度的影响问题。数字仿真和实验结果验证了定子电阻在线辨识的必要性和该方案的有效性。     

Impact of Multimedia Traffic Characteristics on ATM Network Configuration

This paper proposes a new topological designmethod, named BXCQ, which optimizes logical networkconfiguration while guaranteeing Quality-of-Service(QoS) requirements for each service class in an ATMnetwork. The BXCQ method determines the optimum logicalnetwork topology associated with each service class soas to minimize network cost. In our previously proposedFull-Net architecture these different logical topologies can be suitably mapped at the sametime on the same ATM physical network by using theVirtual Channel Handler (VCH) to create differentlogical interconnection networks. The BXCQ method allows us to clarify the relations between multimediatraffic characteristics and desirable logical networkconfigurations in Full-Net. Evaluation results suggestthat a service class that is bursty, delay tolerant, and cell loss sensitive with small demandshould be supported by a loop-like topology. This studywill be useful for designing flexible and cost-effectivemultimedia networks that can also adapt to not-yet-known services.     

Feasibility of a 1,400 m Span Steel Cable-Stayed Bridge

This paper describes the feasibility of 1,400 m steel cable-stayed bridges from both structural and economic viewpoints. Because the weight of a steel girder strongly affects the total cost of the bridge, the writers present a procedure to obtain a minimum weight for a girder that ensures safety against static and dynamic instabilities. For static instability, elastoplastic, finite-displacement analysis under in-plane load and elastic, finite-displacement analysis under displacement-dependent wind load are conducted; for dynamic instability, multimodal flutter analysis is carried out. It is shown that static critical wind velocity of lateral torsional buckling governs the dimension of the girder. Finally, the writers briefly compare a cable-stayed bridge with suspension bridge alternatives.