Long-term

The third of the major hazards and the one with the greatest disaster potential is the release of toxic chemicals. The hazard posed by toxic release depends not only on the chemical species but also on the conditions of exposure. The high disaster potential from toxic release arises in situations where large numbers of people are briefly exposed to high concentrations of toxic material, i.e., acute exposure. However, the long-term health risks associated with prolonged exposure at low concentrations, i.e., chronic exposure, also present serious hazards. 

The purpose of chemical processes is not to make chemicals The purpose is to make money. However, the profit must he made as part of a sustainable industrial activity which retains the capacity of ecosystems to support industrial activity and life. This means that process waste must be taken to its practical and economic minimum. Relying on methods of waste treatment is usually not adequate, since waste treatment processes tend not so much to solve the waste problem but simply to move it from one place to another. Sustainable industrial activity also means that energy consumption must be taken to its practical and economic minimum. Chemical processes also must not present significant short-term or long-term hazards, either to the operating personnel or to the community. 

When electricity is bought from centralized power generation companies, the price tends to be more stable than fuel costs, since power generation companies tend to negotiate long-term contracts for fuel supply. 

For the long term, 2010-2020 refinery complex meeting environmental reg 4)atimn and ensuring total conversion of the heavy ends... 

Even if geological conditions for the presence of hydrocarbons are promising, host country political and fiscal conditions must also be favourable for the commercial success of exploration ventures. Distance to potential markets, existence of an infrastructure, and availability of a skilled workforce are further parameters which need to be evaluated before a long term commitment can be made. 

Exploration activities are aimed at finding new volumes of hydrocarbons, thus replacing the volumes being produced. The success of a company s exploration efforts determines its prospects of remaining in business in the long term. 

Introduction and commercial application Safety and the environment have become important elements of all parts of the field life cycle, and involve all of the technical and support functions in an oil company. The Piper Alpha disaster in the North Sea in 1988 has resulted in a major change in the approach to management of safety of world-wide oil and gas exploration and production activities. Companies recognise that good safety and environmental management make economic sense and are essential to guaranteeing long term presence in the industry. 

A suitable maintenance strategy should be developed for equipment by considering the criticality and failure mode, and then applying a mixture of the forms of maintenance described above. In particular, the long-term cost of maintenance of an item of equipment should be estimated over the whole life of the project and combined with its capital cost to select both the type of equipment and form of maintenance which gives the best full lifecycle cost on a discounted basis), while of course meeting the technical, safety and environmental specifications. 

Preliminary in-field applications have also confirmed the successful long-term performance of the AEBIL instrumentation in power plant environment. 

Results of Long-term On-line Structural Integrity Surveillance of H.T./H.P. Steam Headers by an Innovative Acoustic Emission Approach. 

The paper focuses on the presentation and discussion of the results of the application of long term, continuous, AE structural monitoring to 2 large superheated (SH) steam outlet headers, belonging to 2 different full-size (600 MW, supercritical multifuel) ENEL power units. Continuous AE surveillance of the 2 SH headers started in October 1996 and is still ongoing. 

Part II Qualitative control and long term stability of imaging devices... 

Part II Qualitative Control and Long Term Stability of Imaging Devices... 

Both options 2 and 3 are compatible with our long term innovation strategy to further improve ecology as well as speed and user-friendliness of classical industrial radiography. 

Lambert,P Predicting and achieving serviceability, Proceedings of International seminar Management of Concrete Structures for Long Term Serviceability University of Sheffield, 1997... 

At an early stage of the development of the Inspection Management approach it was recognised that the currently employed commercial arrangements would not be appropriate for the long term commitments envisaged (ref 3). At that time contracts were largely time and materials or reimbursable, which experience had proven in many circumstances to be adversarial by there very nature At its crudest, the objective of the... 

Summarizing, from a mathematical point of view, both forward and backward analysis lead to the insight that long term trajectory simulation should be avoided even with symplectic discretizations. Rather, in the spirit of multiple as opposed to single shooting (cf. Bulirsch [4, 18]), only short term trajectories should be used to obtain reliable information. 

Remark. The authors are well aware of the commonly shared belief within the physics MD community that the apparent chaos does not destroy all long term information, but only irrelevant information in particular, average quantities are supposed to be not sensitive to numerical perturbations. We do not aim at deciding about this fundamental question here. 

As a consequence of this observation, the essential dynamics of the molecular process could as well be modelled by probabilities describing mean durations of stay within different conformations of the system. This idea is not new, cf. [10]. Even the phrase essential dynamics has already been coined in [2] it has been chosen for the reformulation of molecular motion in terms of its almost invariant degrees of freedom. But unlike the former approaches, which aim in the same direction, we herein advocate a different line of method we suggest to directly attack the computation of the conformations and their stability time spans, which means some global approach clearly differing from any kind of statistical analysis based on long term trajectories. 

The long term behavior of any system (3) is described by so-called invariant measures a probability measure /r is invariant, iff fi f B)) = ft(B) for all measurable subsets B C F. The associated invariant sets are defined by the property that B = f B). Throughout the paper we will restrict our attention to so-called SBR-measures (cf [16]), which are robust with respect to stochastic perturbations. Such measures are the only ones of physical interest. In view of the above considerations about modelling in terms of probabilities, the following interpretation will be crucial given an invariant measure n and a measurable set B C F, the value /r(B) may be understood as the probability of finding the system within B. 

Inefficiency of Direct Simulation Suppose we want to compute the corresponding invariant measure p by direct simulation. Direct long term simulation by symplectic discretization of (1) yields the discrete solution ( ) a )i, ... 

E. Hairer and D. Stoffer. Reversible long-term integration with variable step sizes. Report (1995)... 

These various techniques were recently applied to molecular simulations [11, 20]. Both of these articles used the rotation matrix formulation, together with either the explicit reduction-based integrator or the SHAKE method to preserve orthogonality directly. In numerical experiments with realistic model problems, both of these symplectic schemes were shown to exhibit vastly superior long term stability and accuracy (measured in terms of energy error) compared to quaternionic schemes. 

The concept of a symplectic method is easily extended to systems subject to holonomic constraints [22]. For example the RATTLE discretization is found to be a symplectic discretization. Since SHAKE is algebraically equiva lent to RATTLE, it, too, has the long-term stability of a symplectic method. 

In experiments, the two symplectic methods ROT and SPL performed very similarly in terms of error propagation and long term stability. The ex-... 

These experiments confirm observations in the recent articles [20] and [11] symplectic methods easily outperform more traditional quaternionic integration methods in long term rigid body simulations. 

For long term simulations, it turns out that the reproduction of the conservation properties is most important in order to ensure reliable results. 

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