Kalman Ziha

Descriptive sampling in structural safety

Structural system reliability is tackled by Monte-Carlo integration using descriptive sampling. The descriptive sampling is applied instead of the random sampling in the crude Monte-Carlo procedure as well as in the importance sampling procedures. High variance reduction and processing time improvement using descriptive sampling have been encountered.

On the Assessment of Redundancy of Ship Structural Components

This paper firstly sums up some of the views on structural redundancy with particular emphasis on ship and marine structures. Next, it places the engineering decision process in the event space and, consequently, applies the representation of operational modes by systems of events. Furthermore, the paper takes some of the relations from the entropy concept in information theory. The entropy concept in probability theory is employed in the paper to redefine the structural redundancy in terms of conditional entropy of operational modes. The redundancy modeling is presented by systems of operational modes in which some of the transitive events may lead to new operational states. Finally, a ship substructure example of a stiffened panel with a girder is elaborated. The conclusion supports the thesis that the efficient structural redundancy can be comprehended as the most uniform distribution of the operational modes probabilities. Moreover, the efficient structural redundancy can be maximized.Copyright

Fatigue Yield of Ship Structures

The paper on the first place summarizes the fatigue yield approach as a cause-effect interaction between fatigue damage progression and fatigue endurance. Secondly it investigates the fatigue strength worsening on experimental S-N data and the load variability effects in shipbuilding. Next it applies the Classification Society’s rule-based procedure for fatigue analysis of ship’s structure that uses a simplified fatigue strength assessment method. The example elaborates fatigue yield effect on the seagoing operation of a double hull 47400 tdw tanker. At the end the paper recommends the procedure for assessment of ship lifetime shortening due to the fatigue yielding under constant and variable amplitude block loadings.Copyright

Tracing Engineering Evolution with Evolutionary Algorithms

The investigations of the recent complex engineering knowledge, experience, analytical and computational tools may serve to explain the technical progress and facilitate the future development. For this purpose this chapter will present how the evolutionary algorithms can simulate the developing complexity of engineering reasoning that in reverse can back-trace the primitive origins of modern technical products. The chapter will resume the evolutionary algorithms as well as the evolutionary optimization and design processes based on innovative and creative activities with the aim to define their potentialities in discovering the evolution of engineering products.

Uncertainty of multi-level systems of events

The article presents probabilistic uncertainty modeling of multi-level systems of events, mutually linked by transitive events. A method for multi-level systems with potentials to emerge new functional states is suggested and the application is illustrated by a two-level example of systems pertinent to a game with a die and a coin. The presented procedure provides analogy to more complex transitive systems operating in uncertain circumstances with a redistribution of capabilities and demands in case of cascades of failures.

Statistical variability vs. probabilistic uncertainty

The concepts of variability and uncertainty came from experience and coexist with different connotations. First, the article reviews the statistical methods for variability assessments of probability distributions. Next, it sums up the entropy concept of uncertainty of systems of events in probability theory. The two concepts are brought closer together on the basis of common experience of predictability. The article also considers the concept of average number of equally probable events based on entropy. Then, it introduces the concept of equivalent number of outcomes based on variability of probability distributions. Finally, the link between variability and uncertainty is illustrated with examples.

Back-Tracing Technical Progress with Evolutionary Algorithms

This paper investigates the engineering development as an evolutionary process. Therefore it first reveals the benefits of evolutionary algorithms in engineering and considers the evolutionary design. Next it brings a simple analytical model of a common ship hull subjected to service conditions. Finally the optimization in the ship structural design is considered as an evolutionary process tackled by NSGA-II algorithm that is applied in back-tracing of the ship scantling development. The conclusion is that the history of technical development can support comprehension of the role of environment, knowledge, material properties and workmanship in engineering regarding safety, efficiency and manufacturing.

Information of Joint and Marginal Probability Distributions

The paper in the first place reviews the information and the uncertainty measures of joint and marginal probability distributions of the sets and subsets of random events. Next it reminds on the relations of the unconditional and conditional entropy of joint and marginal distributions and their combinations. Then it elaborates the ways how these measures can be applied in the sea surface uncertainty evaluation, that is, how to gain the information from the wave properties visually observed and brought together in the global wave statistics. Furthermore, the examples offered demonstrate the computational procedures for the sea surface uncertainty evaluation and prospective usefulness of the information obtainable from the joint and marginal distributions of observed explicit and combined wave properties.

Uncertainty of sequences of events

The paper investigates uncertainties of occurrences of sequences of events employing the entropy concept. Some aspects of probabilistic engineering event oriented system analysis also are summarized. Joint and successive sequences of events are considered with particular concern with uncertainties that could be associated with them. Numerical examples attempt to demonstrate the procedure and helpfulness to engineering modeling problems for member selection optimization

Handling engineering design experience

We present trials in handling of engineering design experience in industrial and academic communities. Advanced CAD/CAM and other computerized supporting tools are applied on different hardware platforms in a network environment, relating to shipbuilding. First, the ship construction process is briefly summarized with emphasis on current design methods and tools. Next, the handling of design experience with respect to increasing importance of remote education and of remote interaction among a number of different internal and external participants with distributed responsibilities, has been investigated. Finally, a framework of a design experience collection in ship construction based on Web technology is provided for network-aided design team collaboration in shipbuilding, as well as for higher-level distance educational purposes.