Project Overview

In ACTORS media and signal streams will be modeled as data-flow networks. The streams will be mapped onto Linux threads and execute in a virtual CPU under the control of a reservation-based scheduler. Feedback will be used to dynamically adjust the size of the reservations based on actual resource consumption and quality-of-service (QoS) (global feedback) and to adjust the resource consumption within the individual streams (local feedback).

Data-Flow Based Modeling

The standard imperative programming model (e.g. C/C++) is not always the best choice for utilizing modern hardware to the maximum. By raising the abstraction level a few steps we can present the algorithm developer with a less cluttered programming view and at the same time generate code with an improved level of quality. For a large class of embedded system applications including feedback control, signal processing and multimedia streaming and processing, dataflow models and dataflow languages, in particular actor languages, have superior properties.

Actors provides a logical separation of different aspects of an algorithm, namely

– implementation,
– communication, and
– scheduling.

This allows for development of predictable systems composed from a set of reusable components, i.e. actors. In traditional programming methods these different properties of an algorithm are interwoven, and often not formally specified, which makes composition and analysis of expected behaviour impossible.

An actor application consists of a network of actors, which in turn may be viewed as an actor itself, and hence provides a proper and predictable mechanism for encapsulation and modularisation. How the actors communicate internally and how they are scheduled depend on the particular model of computation (MoC) for that network. Actors and actor networks may be composed in a hierarchical fashion and may also have different MoCs.

The ACTORS project is based on the CAL language, a data flow oriented actors language that has recently been specified and developed as subproject of the Ptolemy project at the University of California at Berkeley. An actor is a modular component that encapsulates its own state. The only interaction between actors is through FIFO channels connecting ”output ports” to ”input ports”, which they use to send and receive ”tokens”.

Since CAL is a smaller and more constrained language than C/C++ the possibilities to generate efficient code are larger. This is particularly important for next generation of microprocessors with special instruction sets for media processing. In ACTORS code generation is performed from CAL directly to machine language, e.g., to ARM11 multicore platforms.


In the systems of today, resource usage in terms of CPU, memory, power, bus utilization, etc., is done in a most ad hoc manner. Moreover, software components that in some respect misuse the common resources are hard to detect and reconfigure. By introducing virtualization, or virtualization-like techniques, including everything from virtual machines to bandwidth scheduling, we have the necessary means for providing different levels of isolation. Virtualization such as reservation-based scheduling (RBS) allows functions and applications to share the processor without temporal or spatial interaction. Reservations can easily be composed, are easier to develop and test, and provide security support.
Feedback Control

In many embedded systems worst-case designs are unfeasible for several reasons. One of these is the over-provisioning of resources that this typically implies. Other reasons are uncertainties associated with worst-case resource utilization estimates and on-line changes in objectives, external conditions and use cases. In a feedback-based resource management system, the allocation of resources is based on a comparison of the actual resource utilization by, e.g., a set of activities or tasks, with the desired resource utilization. The difference is then used for deciding how the resources should be allocated to the different activities. The decision mechanism constitutes the feedback controller in the scheduling scheme. Feedback control makes it possible to deal with uncertainties and variations in a controlled way.


Adaptivity and Control of Resources in Embedded Systems

ACTORS addresses design of resource-constrained software-intensive embedded systems with high requirements on adaptivity and efficiency. Three techniques will be combined:

  • virtualization,
  • feedback control, and
  • data-flow programming models.

Virtualization techniques such as reservation-based scheduling provide spatial and temporal separation of concerns and enforce dependability and predictability. Reservations can be composed, are easier to develop and test, and provide security support.

Using feedback-based resource management, the resource allocation is based on a comparison of the actual resource utilization of, e.g., a set of activities or tasks, with the desired resource utilization. The difference is used for deciding how the resources should be dynamically allocated. Feedback control makes it possible to deal with uncertainties and variations in a controlled way and provides adaptivity to on-line changes in objectives, external conditions and use cases. By combining feedback control with resource reservations it is possible to handle incorrect reservations, reclaim and redistribute unused resources, and adjust to dynamic
changes in resource requirements.

Execution efficiency and development efficiency require abstractions on a higher level than what is provided with C and threads/priorities. Data-flow models such as actor models provide the proper foundation for implementation of efficient, component based, and adaptive algorithms for both multimedia applications in consumer electronics and industrial control systems and signal processing applications. In ACTORS a design methodology will be developed that combines virtualization, feedback and actors-based dataflow programming. Three demonstrators will be developed:

  • multimedia processing on cellular phone terminals,
  • embedded control, and
  • high-speed video processing for computer vision applications.

Raisins And Acne

Even more folks experience from acne compared to any type of various other disorder of the skin, according to the National Principle of Joint inflammation as well as Bone and joint and also Skin Conditions. When it comes to acne, raisins are a double-edged sword.

A research study testimonial released in the September 2004 version of the clinical journal “Facilities in Dermatology” keeps in mind that diet plan is an under-appreciated facet of acne advancement as well as administration. The testimonial advises that principal acne factors— consisting of skin oxidation, sugar diet plans and also swelling– are all flexible by eating a healthy and balanced diet regimen abundant in vitamins, minerals and also anti-oxidants.

Oxidation is an organic result of your physical body’s metabolic process that could add to the buildup of acne sores. According to study assembled by the California Raisin Advertising and marketing Board, raisins are a bountiful resource of anti-oxidants.

Glycemic Tons

Medical released in the April 2008 “Journal of Dermatological Scientific research” found that embracing a diet regimen abundant in reduced glycemic tons meals aids decrease signs and symptoms of acne. According to the College of Wisconsin, raisins have a high glycemic lots.

Factors to consider

Since acne is a clinical problem, it must be dealt with by a certified skin specialist. As no researches have actually investigated raisin’s influence on acne, it’s uncertain exactly what have an effect on putting or getting rid of raisins from your diet regimen will certainly carry your acne. You could obtain comparable degrees of anti-oxidants without the high glycemic lots by going with antioxidant-rich fresh fruits, such as blueberries, apples as well as oranges.