A graph grammar-based formal validation of object-process diagrams

Two basic requirements from a system’s conceptual model are correctness and comprehensibility. Most modeling methodologies satisfy only one of these apparently contradicting requirements, usually comprehensibility, leaving aside problems of correctness and ambiguousness that are associated with expressiveness. Some formal modeling languages do exist, but in these languages a complete model of a complex system is fairly complicated to understand. Object-process methodology (OPM) is a holistic systems modeling methodology that combines the two major aspects of a system—structure and behavior—in one model, providing mechanisms to manage the complexity of the model using refinement-abstraction operations, which divide a complex system into many interconnected diagrams. Although the basic syntax and semantics of an OPM model are defined, they are incomplete and leave room for incorrect or ambiguous models. This work advances the formal definition of OPM by providing a graph grammar for creating and checking OPM diagrams. The grammar provides a validation methodology of the semantic and syntactic correctness of a single object-process diagram.     

The convergence of a PLL with variable parameters

A phase-locked loop with variable parameters is considered. In such a system it is possible to obtain a short convergence time together with a small bandwidth. It is supposed that the PLL's parameters cannot be switched and there is a restriction on the velocity of the parameter variation. An optimal strategy of parameter variation is obtained which gives an improvement in convergence time by a factor of about 30 in comparision to fixed parameter and small-bandwidth PLLs.     

Sequential Dynamic Logic

We introduce a substructural propositional calculus of Sequential Dynamic Logic that subsumes a propositional part of dynamic predicate logic, and is shown to be expressively equivalent to propositional dynamic logic. Completeness of the calculus with respect to the intended relational semantics is established.     

Two-terminal routing games with unknown active players

We analyze 2-terminal routing games with linear cost functions and with unknown number of active players. We deal with both splittable and unsplittable models. We prove the existence and uniqueness of a symmetric safety-level equilibrium in such games and show that in many cases every player benefits from the common ignorance about the number of players. Furthermore, we prove new theorems on existence and uniqueness of equilibrium in 2-terminal convex routing games with complete information.     

Failure Analysis of Modular-Block Reinforced-Soil Walls during Earthquakes

Several modular-block reinforced-soil retaining walls failed during the 1999 Ji-Ji (Chi-chi) earthquake of Taiwan. Similar walls showed distress during the 1994 Northridge, Calif., earthquake. The instability or failure of these walls offered an opportunity to validate the simplistic pseudostatic limit-equilibrium procedures. In this study, the Ta Kung Wall of the Ji-Ji earthquake is analyzed, and the Gould and Valencia Walls of the Northridge earthquake are revisited with an improved estimation of local site acceleration. The local acceleration was estimated by using simple attenuation relationships obtained through the earthquake records. The results of analysis indicate that these three walls had adequate internal stability under estimated site acceleration. The geosynthetic length was inadequate to resist compound modes of failure where the potential failure surface extends beyond the reinforced zone. The external stability was most critical in the presence of horizontal and vertical accelerations.     

Empathy and ego development.

Examined the relationship between empathy and ego development to determine whether, as J. Loevinger (1976) suggested, empathy is characteristic of higher levels of ego development. 51 undergraduates (dormitory advisors) completed the Affective Sensitivity Scale (a measure of empathy) and the Loevinger Sentence Completion Test (a measure of ego development). Analysis of test scores indicated that Ss at higher levels of ego development (I-? and above) had significantly higher empathy scores than did those at lower ego levels. Findings have implications for the selection and training of individuals to serve in counseling or quasi-counseling roles. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Farm and factory in the kibbutz: A study in agrico-industrial psychology.

Surveyed kibbutz communities with a mix of factory and farm jobs to study the effects of industrialization on work and workers while controlling for the effects of urbanization. Questionnaire responses of 476 workers in a representative sample of factories were compared to those of 175 workers in location-matched agricultural branches in 27 kibbutz collective settlements. Factory workers rated their jobs significantly lower than did farm workers on plant manager's leadership, opportunities for self-realization on the job, participation, control, peer relations, and information about the job. However, factory jobs were rated cleaner, easier, and more mental. Factory and farm workers were similar in outcome measures, including supervisory ratings of performance, job satisfaction, mental health, and alienation. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Finite-Element Simulations of Full-Scale Modular-Block Reinforced Soil Retaining Walls under Earthquake Loading

A finite-element procedure was used to simulate the dynamic behavior of four full-scale reinforced soil retaining walls subjected to earthquake loading. The experiments were conducted at a maximum horizontal acceleration of over 0.8 g, with two walls subjected to only horizontal accelerations and two other walls under simultaneous horizontal and vertical accelerations. The analyzes were conducted using advanced soil and geosynthetic models that were capable of simulating behavior under both monotonic and cyclic loadings. The soil behavior was modeled using a unified general plasticity model, which was developed based on the critical state concept and that considered the stress level effects over a wide range of densities using a single set of parameters. The geosynthetic model was based on the bounding surface concept and it considered the S-shape load-strain behavior of polymeric geogrids. In this paper, the calibrations of the models and details of finite-element analysis are presented. The time response of horizontal and vertical accelerations obtained from the analyses, as well as wall deformations and tensile force in geogrids, were compared with the experimental results. The comparisons showed that the finite-element results rendered satisfactory agreement with the shake table test results.     

On the design of geosynthetic-reinforced walls

An important design aspect of a geosynthetic-reinforced wall is specifying the reinforcement length. A simple limit equilibrium analysis, which considers two possible extreme inclinations of a reinforcement's resistance force, shows that predictions based on the K_a-analysis may not be safe. Although rules of thumb to determine embedment length are sometimes superimposed on the K_a-analysis prediction in design, it is demonstrated that such ‘rules’ may not always be safe. Design charts for granular backfill illustrate the effects of the reinforcement's force inclination showing quantitatively that the horizontal inclination required slightly larger tensile resistance force, while underestimating the embedment length.