Composite models of weak gauge bosons

Composite models of quarks, leptons and weak bosons are reviewed. It is shown that they can reproduce the low energy results of the Standard Weinberg-Salam Model of electroweak interactions. The consequences of assuming composite W and Z bosons are examined and many new particles are predicted, including excited W and Z states and their pseudoscalar partners. Estimates of the masses and decay widths of these particles are given. It is also shown that coloured weak bosons may exist in the energy range 100-200 GeV. The decays of a composite Z boson are studied in detail using both a potential model and an effective Lagrangian approach. It is found that the width is likely to be significantly different from that of the elementary Z of the Standard Model, In particular there are additional contributions to the decays Z → qqg and Z → ggg which are likely to affect the total Z width by an appreciable amount. The decay of the Z into hypercoloured particles is also examined and it is found that the width is likely to exceed greatly the current experimental bound. It is concluded that the W and Z bosons are likely to be elementary particles because if they were composite their decay widths would be much greater than is found experimentally, unless of course their internal dynamics are quite unlike the model which has been employed

Automatic Generation of Distributed System Simulations from UML

Nowadays, an object-oriented approach is commonly used for building computer systems. The benefits of the object-oriented method, such as scalability, stability and reusability, make this method suitable for building complex systems, including those in the distributed system area. A distributed system application usually needs to satisfy quite stringent requirements such as reliability, availability, security, etc. and the cost of building such an application will be quite high. It is therefore desirable to be able to predict the performance of the proposed system before the construction begins. In order to do this, it is important to evaluate the requirements of the new system and translate them into a specification (design). The design process helps the system developers to understand the requirements better as well as to avoid misconceptions about the system. From the specification, a simulation program can be built to mimic the execution of the proposed system. The simulation run provides some data about the states of the system and from these data, the performance of the system can be predicted and analysed. UML (Unified Modeling Language) is one example of the object-oriented design methods that has been widely used for specifying system requirements. There are also some object-oriented simulation languages/packages available, for example, SIMULA or C++SIM package, but it is often difficult to transform the system’ s requirements into a simulation program without sound knowledge of some simulation techniques. On top of that, a new simulation program needs to be built each time for different systems, which can be quite tedious. The currently available UML tools do not provide a feature to generate simulation programs automatically from UML specifications. In this paper, we describe a tool for constructing simulation programs in a generic way, based on a simple specification (preferably in a UML notation) by identifying the simulation components and their structure

A UML tool for an automatic generation of simulation programs

For sometime now, Unified Modelling Language (UML) has been accepted as a standard for designing new systems. Its array of notations helps system designers to capture their ideas in a way that is expressive yet easy to understand. One thing that UML lacks though, is a means for predicting the system's performance directly from its design. Performance prediction is a desirable feature that enables us to evaluate whether a particular design is worth implementing or not. This prediction can frequently be obtained by constructing a simulation program that mimics the characteristics of the new system. The information gathered from running the simulation will then allow us to estimate the performance. In this paper, we present a simulation framework that can be used to generate simulation programs straight from UML notations. We also present a tool has been built to demonstrate the feasibility of using this framework to perform such a transformation automatically

Simulation Generation from UML Like Specifications

We describe a tool which transform UML specifications (in a textual form) into C++ code which can be used by C++SIM - a discrete-event process-based simulation facility. A tool written in the Perl scripting language is used to perform the automatic transformation from specification into C++SIM code. As an example we show how the tool is used to generate simulations of a non-trivial fault tolerant distributed computing system. The system was specified in about 180 lines of UML like notation and automatically generated a simulation program of about 1100 lines of C++

Simulation of a telecommunication system using simML

The cost of building a new system is usually quite high and without a proper design, a mismatch might occur between the proposed system and the actual system delivered. One aspect that is important to be investigated prior to the system implementation is its performance. A simulation program could be built to obtain the performance characteristics of the new system, but constructing such a program is not a trivial task. Therefore, it is useful to have a tool that can generate a simulation program automatically from a design notation. We have developed a generic syntax based on the UML design notation which is transformable into a simulation program. A tool that performs the transformation automatically has also been built, and in this paper, we present our experience in designing a new telecommunication system-using our syntax and tool

Projected impacts of 21st century climate change on diapause in Calanus finmarchicus

Diapause plays a key role in the life cycle of high latitude zooplankton. During diapause animals avoid starving in winter by living in deep waters where metabolism is lower and met by lipid reserves. Global warming is therefore expected to shorten the maximum potential diapause duration by increasing metabolic rates and by reducing body size and lipid reserves. This will alter the phenology of zooplankton, impact higher trophic levels and disrupt biological carbon pumps. Here we project the impacts of climate change on the key North Atlantic copepod Calanus finmarchicus under IPCC RCP 8.5. Potential diapause duration is modelled in relation to body size and overwintering temperature. The projections show pronounced geographic variations. Potential diapause duration reduces by more than 30% in the Western Atlantic, whereas in the key overwintering centre of the Norwegian Sea it changes only marginally. Surface temperature rises, which reduce body size and lipid reserves, will have a similar impact to deep water changes on diapause in many regions. Because deep water warming lags that at the surface, animals in the Labrador Sea could offset warming impacts by diapausing in deeper waters. However, the ability to control diapause depth may be limited

Fault-Injection-Based Assessment of Fail-Silence Provided by Process Duplication versus Internal Error Detection in Scientific-Based Applications

Coordinated Science Laboratory was formerly known as Control Systems Laborator

Can a key boreal Calanus copepod species now complete its life-cycle in the Arctic? Evidence and implications for Arctic food-webs

The changing Arctic environment is affecting zooplankton that support its abundant wildlife. We examined how these changes are influencing a key zooplankton species, Calanus finmarchicus, principally found in the North Atlantic but expatriated to the Arctic. Close to the ice-edge in the Fram Strait, we identified areas that, since the 1980s, are increasingly favourable to C. finmarchicus. Field-sampling revealed part of the population there to be capable of amassing enough reserves to overwinter. Early developmental stages were also present in early summer, suggesting successful local recruitment. This extension to suitable C. finmarchicus habitat is most likely facilitated by the long-term retreat of the ice-edge, allowing phytoplankton to bloom earlier and for longer and through higher temperatures increasing copepod developmental rates. The increased capacity for this species to complete its life-cycle and prosper in the Fram Strait can change community structure, with large consequences to regional food-webs