Analogue electronic circuit diagnosis based on ANNs

Feed-forward artificial neural networks (ANNs) have been applied to the diagnosis of nonlinear dynamic analogue electronic circuits. Using the simulation-before-test (SBT) approach, a fault dictionary was first created containing responses observed at all inputs and outputs of the circuit. The ANN was considered as an approximation algorithm to capture mapping enclosed within the fault dictionary and, in addition, as an algorithm for searching the fault dictionary in the diagnostic phase. In the example given DC and small signal frequency domain measurements were taken as these data are usually given in device’s data-sheets. A reduced set of data per fault (DC output values, the nominal gain and the 3 dB cut-off frequency, measured at one output terminal) was recorded. Soft (parametric) and catastrophic (shorts and opens) defects were introduced and diagnosed simultaneously and successfully. Large representative set of faults was considered, i.e., all possible catastrophic transistor faults and qualified representatives of soft transistor faults were diagnosed in an integrated circuit. The generalization property of the ANNs was exploited to handle noisy measurement signals.     

Leukotrienes in allergic inflammatory reactions

Production of leukotrienes, lipooxygenase products of arachidonic acid metabolism, plays an important role in inflammatory reactions, particularly well studied in bronchial asthma. Lipooxigenase-5 and lipooxygenase-activating protein-5 are crucial in the production of leukotrienes with potent biological activities. Leukotriene B4 is a leukocytic chemoattractant and it induces aggregation and adherence of leukocytes to endothelial vasculature. Sulfidopeptid leukotrienes (C4, D4 and E4) are potent bronchoconstrictors, producing mucous secretion in the airways and increasing vascular permeability. Leukotrienes participate in the process of inflammation, as well as in early and late asthmatic responses. They are found in the blood, liquid obtained upon bronchoalveolar lavage as well as in the urine, irrespectively whether bronchospasm developed spontaneously or it was induced by an allergen. Administration of the specific leukotriene receptor antagonists or leukotriene synthesis inhibitors ameliorates the symptoms and signs of bronchial asthma.     

Frequency and time domain comparison of selective polynomial filters with corrected phase characteristics

Two solutions to the polynomial filter’s transfer function synthesis problem are considered for comparison in the frequency and time domain: the broad class of filters with a critical monotonic amplitude characteristic (CMAC) in the passband and filters which use Chebyshev (C) polynomials. To complete the synthesis procedure for linear phase applications, group delay correctors are considered, for which a convenient approximation procedure is proposed here. Comparisons of the original functions and the corrected ones are performed in the frequency and time domain. It is shown that when CMAC and C are compared as such, the latter is by no means preferable from the selectivity point of view, while the opposite stands when the comparison is based on passband amplitude distortions. When phase-corrected filtering functions are compared, based on circuit complexity and time domain performance, the CMAC are shown to be preferable.     

Application of a Standard Power Meter for Detection Source of Harmonic Pollution and Reducing Economic Losses at Power Grid

Abstract—

The modern utility system is faced with two main problems: how to minimize losses in a power system and how to locate the source of harmonic pollution. Namely, the utility has losses whenever the power it delivers is greater than the power it registers at the point of common coupling (PCC). In this paper we will show that these losses occur because the measurement equipment and billing policy are not adequate, and we will stress the reasons why this happens. The main reason is the distortion power generated by nonlinear loads. The number of these loads at power grid is greater every day, thus enlarging the problem. Ordinary power meters are not able to measure distortion power, so in this paper we will also show which small modifications to existing ordinary meters needed, which could lead to the successful detection of sources of harmonic pollution, thus further reducing power losses. The suggested idea will be verified by numerous simulations and measurements on different household/office and industry loads that are commonly used. The proposed method is suitable either for software or hardware upgrade of existing smart meters, or it can be implemented on ordinary measurement systems.     

Distribution of iron,zinc and manganese in milling streams of common Serbian wheat cultivars: Preliminary survey

This study investigates distribution of three micronutrients in milling streams of three common wheat cultivars to estimate nutritive value of white and brown flours. Among the analysed wheat cultivars, the majority of flour streams of NS Todorka showed a higher content of soluble micronutrients than the other two investigated wheat cultivars. It is necessary to improve bioavailability of Fe and Zn in flours since these micronutrients were mostly in insoluble form. In contrast, considering average Serbian portion sizes for bread, bread made from flour Type ‘110’ could supply almost 75% of the recommended daily intake for Mn.     

A New Method for Pore Pressure Prediction on Malfunctioning Cells Using Artificial Neural Networks

Embankment rockfill dams are the most common dam construction types used in the world today. One third of all embankment dam failures are caused by dam slope instability. The dam is stable when the slopes are stable. Slope safety of the dam is assessed through pore and total pressure data analysis registered on pressure measurement cells installed in the dam. During the service life of a dam, one or more cells may malfunction after years of operation. Cell replacement implies economically unjustified high costs and is usually technically impossible and high risk. In this paper, the problem of a malfunctioning cell with a small available dataset is analysed. A new method for pore pressure prediction on malfunctioning cells has been developed using several successive artificial neural networks (ANNs) to obtain high accuracy of the predicted values. The results show that these predicted values are more precise than values we could have obtained using only one artificial neural network for prediction.

     

Computer Security Vulnerability as Concerns the Electricity Distribution Grid

The usual way of creating a cyber attack is through implementation of malware via the Internet. Among many types of malware, of special interest are those that enable eavesdropping on the activities within the computer, making it possible to define the software on which the computer is running. An adversary can benefit from this information in a way that is convenient for him or her. Here, we expose a new, entirely different way of eavesdropping and of monitoring the activities within the computer. It is based on measurement of the supply current taken from the electricity distribution grid. Because the computer, as many other electronic loads, is a nonlinear one, abundance of harmonics can be found in that current. Our discovery is the fact that the harmonic content is dependent on the type of activity within the computer, so, by proper analysis of the current waveform, one may recognize what is going on in it. We propose an artificial neural network-based method that unambiguously recognizes which software is running. We also propose a proper measurement procedure based on the technology we described in our earlier articles.     

Laboratory diagnosis of allergic inflammation

Monitoring of allergic inflammation includes direct examination of biopsy specimens from mucosa and epithelium, and indirect study by sputum, bronchoalveolar and nasal lavage fluid and peripheral blood. Although, some of these detection assays are not applicable to clinical use, it is now possible to measure a number of inflammatory mediators released from cells participating in allergic disease. The release of performed histamine from peripheral blood basophils challenged with specific antigen remains a valuable in vitro correlate of immediate hypersensitivity reactions. However, other mediators such as LTC4 and IL-4 are also generated by basophils upon IgE dependent activation. Tryptase and PGD2 are released from mast cells upon activation. Eosinophils contain in their granules proteins that cause damage to the bronchial epithelium: MBP and ECP. It is possible to measure soluble markers from other cells (T cells, macrophages, platelets, endothelial cells) involved in allergic inflammation. Detection of mediators have produced data that have significantly added to our understanding of the mechanisms and allowed better pharmacological control of allergic inflammation.