Special Aspects of Fixing Interfering Source Located in Close Proximity to Radio-Electronic Equipment with Multi-Channel Receiver and Estimate of Accuracy

One of the fundamental properties of modern radio electronic equipment (REE) is jammer-induced performance in particular when located near REE, when they significantly affect the parameters of electromagnetic field generated and/or received by REE. One of the ways of antijamming is its rapid detection by REE for elimination purpose. In solving this problem, both the minimum detection time and the accuracy of the noise source location are equally important. In this article, the problem is considered using the example of radar detection with a multi-channel receiving device and thrown noise transmitter located close to its antenna field. The schemes displaying the problem geometry for phase and difference-distance-measuring methods for determining of jammer position are presented. Expressions are formed that determine the area of uncertainty zone when jammer detecting and connection of this value with radar parameters – ranging and azimuth accuracy. The necessity of using expressions free of far zones assumptions with respect to the radar and jammer relative position is explained. Ranging based on the signal received by radar in the mode of circular or sector review is considered. The results obtained confirm the necessity to take into account the distance between the jammer and REE when implementing the basic methods for determining radiation source location.

ADVANCED EXPERIMENTAL BIFURCATION ANALYSIS: BASELINE SCENARIO OF DYNAMICS EVOLUTION

The paper develops the advanced experimental bifurcation analysis, where the extended data acquisition, the intelligent data processing, and the modified bifurcation diagrams are combined to get useful information for different specified purposes. In particular, here we focus on how to estimate experimentally the nearest limit of the operating process stability loss without expert opinions. So, we consider the baseline scenario of dynamics evolution, where the peculiarity of the estimation is connected with the possibility to determine the uncertainty zone about the corresponding bifurcation points. The algorithms of both data acquisition and data processing are illustrated. The procedures of the algorithms are founded on the methods of the experimental researches of different nonlinear phenomena under uncertainties. The presented results can be applied to engineering design.

Effect of centrifugal load on crack path in thin-rimmed and webbed gears

Thin rimmed and webbed gears are used in particular applications to reduce systems weight. This kind of gears need an accurate and fail safe design. As a matter of fact, a possible failure, due to bending fatigue, consists in crack nucleation and consequent growth, in particular in the tooth root zone. These cracks may propagate through the tooth or through the rim. Crack propagation direction is basically influenced by the wheel geometry parameters, above all the rim thickness. Studies available in literature emphasize three ranges for the backup ratio values, involving different behaviors. These ranges are related to the crack propagation paths; respectively through the tooth, through the rim and in an unforeseeable way. This last uncertainty zone depends on other parameters, related to both geometry and loading conditions. In this work the effect of wheel speed related to the bending load has been investigated. The investigation has been carried out by means of numerical models involving both 2D finite element and extended finite element models (XFEM). Results shows that both crack initiation point and crack propagation path are strongly influenced by centrifugal load; this effect is mainly evident in the uncertainty zone of the backup ratio.

FRACTAL APPROACH, BIFURCATION POKER AND SUC-LOGIC FOR NONLINEAR DYNAMICS FORECASTING

The paper is devoted to the novel logic (SUC-logic) of the nonlinear dynamics forecasting. The SUC-logic is based on three main points: the special sections (S) to build the 2D projections of multidimensional spaces without the loss of useful information; the special units (U) of measurement to estimate the nonlinear dynamics evolution; the special consecutions (C) to realize the nonlinear dynamics forecasting step-by-step. The fractal approach to forecasting the nonlinear dynamics in real-time together with the approach to build the modified bifurcation diagrams to research the regularities and the uncertainties of the evolution scenarios are developed with the SUC-logic. The physical meaning of the uncertainty zone, the stability margin, the risk estimation, the farthest forecasting and the earliest forecasting are considered from the viewpoint of the nonlinear dynamics aspect. Reasonings and discussions are based on experimental and computational results.

FROM MODIFICATIONS OF EXPERIMENTAL BIFURCATION DIAGRAMS TO OPERATING PROCESS STABILITY MARGIN

The approach to research the uncertainties and the regularities of nonlinear system behavior is developed in the paper. The peculiarity of the approach is connected with modifying the experimental bifurcation diagrams that allows to identify and to analyze certain aspects of the nonlinear dynamics evolution. The variety and the interrelation of the modified bifurcation diagrams are shown. Attention is focused on estimating the limits of the zone within which the nonlinear system behavior is characterized by the uncertainty and on making visible the particular tendencies of dynamics evolution within this zone. The results obtained on the experimental setup of PWM buck converter are used for illustrations. In particular, the uncertainty zone is assumed to be the unit of measurement to estimate the operating process stability margin. It is demonstrated that the properties corresponding to the practical experience appear as per this assumption.

ESTIMATING THE UNCERTAINTY OF THE BEHAVIOR OF A PWM POWER CONVERTER BY ANALYZING A SET OF EXPERIMENTAL BIFURCATION DIAGRAMS

One of the main faults of a PWM power converter is linked to losing the operating process stability because of bifurcations. A bifurcation diagram contains information on the evolution of the behavior of a PWM power converter that could be theoretically used to prevent the bifurcations. Surprisingly, applying the bifurcation analysis is not yet typical in engineering practice. One of the reasons seems to be in the fundamental properties of the PWM power converter dynamics caused by the unavoidable uncertainty of its behavior near a bifurcation point. We propose a new approach to estimating this uncertainty. By analyzing a set of experimental bifurcation diagrams, our approach allows to determine both the location of the uncertainty zone and the quantitative regularities of the behavior within this zone. The proposed approach can be applied to design and maintenance, including fault diagnosis, and also to scientific research of the nonlinear dynamics regularities. Our results are experimentally verified by using the "PWM DC drive" setup.

How to Reduce Uncertainty in a Context of Innovation: The Case of IBM's Negotiation of its European Works Council

Uncertainty is one of the natural consequences of innovation. Regardless of the particular area, innovation leads to unknown situations ranging from the creation of high-tech new products to profound modification of economic and social structures. This uncertainty creates difficulties for negotiation processes because it becomes almost impossible to anticipate all the consequences of any agreement. Consequently, innovation tremendously enhances the uncertainty of a negotiator with regard to his own interests. Uncertainty about the opponent's interests and behavior is of course another major concern and has been dealt with extensively by many authors. This paper deals with the very different concept of uncertainty regarding one's own interests. It analyzes the impact of this form of uncertainty in the negotiation process, examining the 1997–1999 negotiations at IBM over the implementation of a European Works Council. We show that when a negotiator is uncertain about his own interests, he is less inclined to consider positions located in his uncertainty zone. This occurs as soon as he discoevers an acceptable outcome outside of this zone, even when the agreement is little differentthan the status quo. The negotiator will persist in such a strategy even though alternative agreements located in the uncertainty zone could be more advantageous for one or even both parties. In order to enlarge the zone of potential agreements between parties, a negotiator should undertake one further step: exploration of his own uncertainty zone. We demonstrate that the adoption of such a strategy, is innovative in and of itself, requiring a pro-active and creative attitude on the part of negotiators in order to discover appropriate uncertainty reduction mechanisms.

The Cambridge Cognitive Examination (CAMCOG): A validation study in outpatients suffering from dementia and non-demented elderly subjects (including Age Associated Cognitive Decline patients) in Greece

Introduction: The Cambridge Cognitive Examination for the elderly (CAMCOG) was first published in 1986 as a reliable instrument for the study of patients with cognitive function impairment. Objective: To standardize the Greek version of CAMCOG. Setting: Dementia Outpatient Clinic, 3rd Department of Neurology, Aristotle University of Thessaloniki. Participants: 150 nondemented controls and 100 patients suffering from mild to severe dementia of various types took part in the study. Results: CAMCOG manifests Cronbach's alpha=0.93. In the group of patients under 75, sensitivity (Sn) is 90.00 percent at the level of 76/77 and specificity is 91.89 percent at the level of 70/71. The respective scores for the group of patients over 74 are 68/69 (Sn=90.00 percent) and 60/61 (Sp=92.30 percent). It seems that CAMCOG shows an “uncertainty zone” in both groups between the scores of 71 to 76 for the first group and of 61 to 68 for the second. The MMSE cut-off point, for the two groups are 23/24 (Sn=94.28 percent, Sp=90.99 percent) and 22/23 (Sn=96.60 percent, Sp=94.87 percent), respectively. Conclusion: The Greek version of CAMCOG manifests different properties than the original British Version. This is probably due to differences in education and social background (e.g., cultural isolation of rural areas). MMSE performs better than CAMCOG mainly because diagnosis is based on the assessment of fundamental aspects of cognitive function, which is reflected in MMSE in a way that is less affected by the mental or educational status of the subject.