Piezo is essential for amiloride-sensitive stretch-activated mechanotransduction in larval Drosophila dorsal bipolar dendritic sensory neurons

Date of Acceptance: 05/06/2015Peer reviewedPublisher PD

The solar WIND and suprathermal ion composition investigation on the WIND spacecraft

The Solar Wind and Suprathermal Ion Composition Experiment (SMS) on WIND is designed to determine uniquely the elemental, isotopic, and ionic-charge composition of the solar wind, the temperatures and mean speeds of all major solar-wind ions, from H through Fe, at solar wind speeds ranging from 175 kms −1 (protons) to 1280 kms −1 (Fe +8 ), and the composition, charge states as well as the 3-dimensional distribution functions of suprathermal ions, including interstellar pick-up He + , of energies up to 230 keV/e. The experiment consists of three instruments with a common Data Processing Unit. Each of the three instruments uses electrostatic analysis followed by a time-of-flight and, as required, an energy measurement. The observations made by SMS will make valuable contributions to the ISTP objectives by providing information regarding the composition and energy distribution of matter entering the magnetosphere. In addition SMS results will have an impact on many areas of solar and heliospheric physics, in particular providing important and unique information on: (i) conditions and processes in the region of the corona where the solar wind is accelerated; (ii) the location of the source regions of the solar wind in the corona; (iii) coronal heating processes; (iv) the extent and causes of variations in the composition of the solar atmosphere; (v) plasma processes in the solar wind; (vi) the acceleration of particles in the solar wind; and (vii) the physics of the pick-up process of interstellar He as well as lunar particles in the solar wind, and the isotopic composition of interstellar helium.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43776/1/11214_2004_Article_BF00751327.pd

On Non-deterministic Supervisory Control

The supervisory control theory (SCT) is examined in a non-deterministic setting. We show that language controllability of a supervisor is not necessarily equivalent to state controllability when the supervisor is nondeterministic. We give necessary and sufficient conditions for when equivalence holds. The input/output interpretation of the SCT is also examined in a nondeterministic setting. It is known that for a supervisor to act as a controller generating commands for the plant, the supervisor has to be inverse state controllable. We give sufficient conditions for when inverse state controllability is equivalent to inverse language controllability. In systems with concurrently competing production sequences, such as flexible manufacturing systems and multi-purpose batch plants, the specification typically becomes non-deterministic where several products compete for the same production resource. However, unless the plant is only partially observable, it is normally modeled as a determ..

Object-Oriented Supervisory Control with a Class of Non-Deterministic Specifications

reusable software components, together with algorithms for automatic synthesis of the control software. In this paper will be shown how a certain type of nondeterministic specification for discrete event systems can be used with the supervisory control theory. A discrete event system will be regarded as a user-resource system, with a set of resources shared by a set of users. The users are seen as a specification on the behavior of the system. The sharing of the resources is modeled by interleaving the users, which results in a certain kind of nondeterministic specification. It is shown that the supervisory control theory still holds in this context, with a slight modification of the definition of supervisor completeness. 2. USER-RESOURCE SYSTEMS The systems arising from the modeling described in [3] contain a finite set of resources, autonomous reusable software models, each described as a Discrete Event Process (DEP). They are all considered deterministic, a not unrealistic assumpt..

Distributed Objects For Real-Time Control Systems

In this paper we will show how object-oriented techniques can be used for the structuring and implementation of large real time control systems. We map the physical system into a set of selfcontained software models - internal resources - that interact through high-level messages. These objects encapsulate specific control aspects from the synchronization necessities of the overall system. The synchronization is administered by an application-specific entity - a controller. We further argue that this controller is best implemented as a distributed object, leading to a productrelated view of the system. Such a controller can be generalized, driven by adaptable recipes that describe the workprocess, giving a high-level implementation mechanism specifically developed for expressing distributed control of fabrication processes. Keywords Discrete event systems, Real time control, Object orientation, Distributed control, Finite automata, Process industry control 1. INTRODUCTION natural way,..

Petri Nets and Control Synthesis: An Object-Oriented Approach

When implementing control of discrete event systems, the efficiency and reliability would be greatly improved if the control algorithms could be automatically synthesised. Using reusable software modules as models of the physical resources, and part-routing as specifications on the system-behavior, we will show how such automatic generation of control algorithms can be achieved. Our approach is based on the Supervisory Control Theory (SCT) developed by Ramadge and Wonham. The machining resources are modeled by Petri Nets. The part-routes are also given as Petri Nets describing the order in which each part should, or can (alternative routes are allowed) visit the respective resources, together with which operation the resource is to perform on the individual part. The parts' desired routes, are individually specified irrespective of parts of other types, even though they may compete for mutual resources. The part specifications, seen now as users of the resources, are composed into a jo..

Hierarchical Supervisory Control for Batch Processes

A Petri net based approach for the modeling of batch plants as well as products is presented. With the focus on synchronization and booking issues, we propose general Petri net building blocks for the construction of recipes. These building blocks prove to be very usable for supervisor synthesis and implementation. We also introduce a hierarchical supervisor structure that implements deadlock avoidance policies when executing a number of concurrent recipes. It is shown that the presented hierarchical supervisor is by far less complex than a non-hierarchical one. I. INTRODUCTION Batch processes take an important place in process industries. A batch process involves a sequence of operations or tasks, each of which is carried out on a discrete quantity of material within a piece of operating equipment. A recipe specifies the sequence of tasks to be executed and all possible ways the plant can be utilized in order to produce the desired product. Thus, it seems quite natural to dis..

Petri Net Constructs for High Level Operation Lists

In this paper will be shown how product routes can be graphically specified in an application unspecific way. This facilitates the implementation of flexible manufacturing cells and enhances the flexibility in that physical changes in the cell will not affect the product descriptions. An operator can also specify independent product routes without concern for other products that may be simultaneously present in the system. Automatic transformations of the product routes into Petri nets is shown, and the Petri nets can further be used for synthesis of correct control laws for the production. 1. Introduction The use of high level product descriptions, operation lists [1] and recipes [8], is motivated by a desire for increasingly flexible manufacturing processes. Flexibility inherently demands a separation between the manufacturing resources, the product routes and the control system. Such a separation permits incorporation of new or different equipment as well as new products without re..

Object Oriented Structuing of Real Time Control Systems

A real time system consists of two parts, a physical system further dissecteable into physical subsystems, and a `psychical' system, comprising the computer control software. The structuring of such a real time control system is a major problem within the control engineering research area. As the number of I/O-signals increase, the system complexity manifolds exponentially. In this paper we will discuss how modern techniques borrowed from the computer science and artificial intelligence community can be used to handle that complexity. We propose the following: . Separate the control of the individual physical subsystems from the synchronization of the system as a whole. . This can be achieved by building software models of the physical subsystems, using the object oriented paradigm. . Encapsulate the control of the physical subsystem by implementing these models in two distinct parts, a general and a specific part. . Make the software models communicate by high level messages, speciall..