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The paper presents some aspects of overhead transmission lines (OHL) modeling for lightning overvoltages estimation in engineering practice. Different models of elements are compared, and sensitivity analysis is performed with the aim to investigate their influence to the OHL insulation stress due to lightning discharges. Elements are modeled according to international technical documents covering this field. Great influence of applied model of air flashover to the lightning current, sufficient to cause back flashover, is noticed. Calculation results obtained with different combinations of element models have been compared and large deviations are noticed. The models of elements for lightning overvoltages estimation should be carefully chosen to achieve reliable estimations. Constant resistance model of tower grounding and voltage-time curve model of air breakdown must be avoided in calculations, despite the fact that they are suggested in many technical documents dealing with lightning overvoltages at OHL. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper proposes a novel algorithm for grayscale image compression based on dual mode quantization that is supported by improved linear prediction scheme. The idea of dual mode quantization comes from desire to exploit advantages of the both uniform and piecewise uniform quantizers, designed for discrete input samples. The algorithm performs quantizers with a low and medium number of quantization levels and with a fixed codeword length by using a pixel value prediction in preprocessing. The correlation of adjacent pixels is exploited as the main idea for improving the quality of image compression. The proposed prediction is linear and very simple for practical realization. An analysis of reconstructed image quality is presented considering several parameters and by comparing with few other methods – BTC, DPCM and with methods that use transformation coding. Experiments are done applying the proposed compression model to several standard grayscale test images. Special attention is given to determination of thresholds values that determine whether and which of the two offered quantizers to use. Moreover, method for determining the value of proposed quantizer’s variance is explained. Obtained results show that proposed model ensures gain up to 6.14 [dB] compared to the BTC model that uses fixed piecewise uniform quantization for discrete input without a pixel value prediction as well as gain up to 5.89 [dB] compared to the DPCM model that applies dual predictor. The proposed algorithm could find application in current grayscale image compression and video standards. [ABSTRACT FROM AUTHOR]

In this paper, a new kind of overhead transmission line (OHL) lightning protection system based on external ground wires is analyzed. Instead of a standard ground wire, two ground wires placed at the top of separate external towers located at both sides of the protected line are used. This type of protection should be applied in specific circumstances for protection of short OHL sections which are highly endangered by lightning. The distance between external protection system and OHL is calculated by using EMTP-ATP. Calculations are performed in order to avoid flashovers from the point where lightning strikes the external protection system to the protected OHL. A rolling sphere method is used to calculate the height of external ground wires above OHL phase conductors to avoid shielding failures. An experiment in a high voltage laboratory is performed to verify the dimensions of the external protection system from the aspect of shielding failures. According to the results of simulation and experiment, the optimal dimensions of the external protection system are determined. [ABSTRACT FROM AUTHOR]

This paper describes specialized software developed to estimate substation and transmission line performance during lightning events. Comparison with similar software packages is also discussed and advantages are noticed. Additionally, this paper describes specific program features that could be applied in the education of students. Supporting computational exercises included in subject curriculum are given as well. The aim of every exercise is clearly defined and some of the estimated results are included. Introduction of presented software package in course curriculum allows teachers to present fundamental concepts and results. Such information attracts students’ attention and makes the lessons more interesting. This leads to better understanding of the presented materials. [ABSTRACT FROM AUTHOR]

Abstract: The influence of wind turbine blade rotation on the lightning behavior is not sufficiently studied. The original theoretical analysis and experimental investigation, whose most important segments are described in this paper, should enable a better understanding of this phenomenon. The tests were conducted in the high-voltage laboratory, applying the up-and-down method for determination of the 50% flashover standard switching voltage. The impulse voltage waves were applied between the specially designed arching electrode and/or the several rod electrodes at discrete positions along the insulating arching cylinder and the blades of a reduced-size wind turbine model, driven by a frequency controlled motor. A lightning protection system in the form of receptors on the tips of the blades was examined. According to the theory of similarity the paper discusses the characteristics of direct atmospheric discharges for the several typical rotational speeds of the wind turbine. It was concluded that the number of direct lightning strikes in the zone of the air termination system on the blades is decreasing due to the rotation of the blades. [Copyright &y& Elsevier]

In this paper, a piecewise uniform quantizer for input samples with discrete amplitudes for Laplacian source is designed and analyzed, and its forward adaptation is done. This type of quantizers is very often used in practice for the purpose of compression and coding of already quantized signals. It is shown that the design and the adaptation of quantizers for discrete input samples are different from the design and the adaptation of quantizers for continual input samples. A weighting function for PSQNR (peak signal-to-quantization noise ratio), which is obtained based on probability density function of variance of standard test images is introduced. Experiments are done, applying these quantizers for compression of grayscale images. Experimental results are very well matched to the theoretical results, proving the theory. Adaptive piecewise uniform quantizer designed for discrete input samples gives for 9 to 20 dB higher PSQNR compared to the fixed piecewise uniform quantizer designed for discrete input samples. Also it is shown that the adaptive piecewise uniform quantizer designed for discrete input samples gives higher PSQNR for 1.46 to 3.45 dB compared the adaptive piecewise uniform quantizer designed for continual input samples, which proves that the discrete model is more appropriate for image quantization than continual model. [ABSTRACT FROM AUTHOR]

The experimental research, whose most important segments are described in this paper, is one of the first attempts to determine the influence of wind turbine blade rotation on likelihood of getting struck by lightning. The tests were conducted in the high-voltage laboratory, applying the up-and-down method for determination of the 50% flashover standard switching voltage. The impulse voltage waves were applied between the specially designed arching electrode and the blades of a reduced-size wind turbine model, driven by a frequency controlled motor. Two types of lightning protection systems and the case of absent protection system were examined. According to the theory of similarity this paper discusses the characteristics of direct atmospheric discharges for the following typical rotational speeds of the wind turbine: w  =  0 r/min (when the wind turbine is idle), w  =  250 r/min (for the winds of moderate strength), and w   =  400 r/min (rated rotor speed). [ABSTRACT FROM AUTHOR]

This paper deals with the calculation of the electric field strength in high voltage (HV) substations comprising complex geometrical structures. Generalized charge simulation method is proposed for improving the precision of the calculation of the electric field strength. The objective of this analysis is to examine the influence of towers, HV apparatus and fences on the spatial electric field distribution. For this purpose, a three-dimensional generalized model of HV substation has been developed, including phase conductors, bypass busbars, HV apparatus, fences and towers (denoted as Full model). The obtained results of the calculation of the electric field strength are compared with the Simplified model, which only includes phase conductors connected to HV network. Verification of the proposed Full model performed by comparing the calculated and in-field measured values of the electric field strength within HV substations and in their vicinity gives very promising results. [ABSTRACT FROM AUTHOR]

Achieving real-time inference is one of the major issues in contemporary neural network applications, as complex algorithms are frequently being deployed to mobile devices that have constrained storage and computing power. Moving from a full-precision neural network model to a lower representation by applying quantization techniques is a popular approach to facilitate this issue. Here, we analyze in detail and design a 2-bit uniform quantization model for Laplacian source due to its significance in terms of implementation simplicity, which further leads to a shorter processing time and faster inference. The results show that it is possible to achieve high classification accuracy (more than 96% in the case of MLP and more than 98% in the case of CNN) by implementing the proposed model, which is competitive to the performance of the other quantization solutions with almost optimal precision. [ABSTRACT FROM AUTHOR]

Background/Aim. Pectus excavatum (PE) is the most common deformity of the frontal aspect of the chest wall in children. A particular dilemma arises about the degree of deformity that should be subjected to surgical treatment. The aim of this study was to compare several morphological methods of evaluating the degree of deformity and determine the matching among them, as well as to determine the connection between the functional and morphological abnormalities of echocardiography. Methods. The study included 35 patients with PE, aged between 7 and 15 years. A noninvasive evaluation of chest deformity was carried out in all patients by photographic method (surrogate of clinical examination), native X-ray imaging, and computed tomography (CT), as well as by echocardiographic examination. Results. In our group of patients, males were more common (67.5%), as well as children with the Haller index (HI) > 3.5 [represented in most children (86.7%)]. A significant correlation of the index of the affected sternum segment (ASt) and the total length of the sternum (ASt/LSt) determined by the photographic method with that determined by the CT scan of the chest was established (p = 0.001). In addition, the correlation between HI, determined by the X-ray method and CT images was presented (p = 0.012). In contrast, despite the high frequency of echocardiographic abnormalities (69%), those were not mutually correlated with the degree of pronounced morphological deformities of the chest wall. Conclusion. A detailed clinical examination and photographic evaluation method, combined with the X-ray method, can determine the severity of deformity with a high degree of agreement with the CT chest findings. In this way, it is possible for children with PE, who are not candidates for surgical treatment, to be spared from repeated CT scans that are carried out in order to monitor the development of chest deformities with growth. Echocardiographic evaluation remains an integral part of the assessment of children with PE. [ABSTRACT FROM AUTHOR]

Background: Burn wound dressing and debridement are excruciatingly painful procedures that call for appropriate analgesia—typically multimodal. Better post-procedural pain management, less opioid use, and consequently fewer side effects, which could prolong recovery and increase morbidity, are all benefits of this type of analgesia. Intravenously administered ketamine can be effective as monotherapy or in combination with opioids, especially with procedural sedation such as in burn wound dressing. Methods: This observational study investigated the effect of ketamine administered in subanesthetic doses combined with opioids during burn wound dressing. The study was conducted from October 2018 to October 2021. A total of 165 patients met the inclusion criteria. A total of 82 patients were in the ketamine group, while 83 patients were dressed without ketamine. The main outcome was the effect of ketamine on intraprocedural opioid consumption. The secondary outcome included the effect of ketamine on postprocedural pain control. Results: Patients dressed with ketamine were significantly older (p = 0.001), while the mean doses of intraoperatively administered propofol and fentanyl were significantly lower than in patients dressed without ketamine (150 vs. 220 mg, p < 0.001; and 0.075 vs. 0.150 mg, p < 0.001; respectively). Conclusions: Ketamine was an independent predictor of lower intraoperative fentanyl consumption, according to the multivariate regression analysis (p = 0.015). Contrarily, both groups of patients required postoperative tramadol treatment, while intraoperative ketamine administration had no beneficial effects on postoperative pain management. [ABSTRACT FROM AUTHOR]

Nosocomnial (hospital) pneumonias (hospital-acquired pneumonia - HAP) are defined as pneumonias in hospitalized patients that occur within 48 hours after admission to the hospital or later. These types of lung parenchymal infections are caused by pathogens that are present in the hospital environment. The incubation period is no longer than two days. Nosocomial pneumonias are the second most common of all hospital infections and the highest prevalence is recorded in intensive care units (ICU) (internal medicine and surgery). They represent a great burden on the health system everywhere in the world, because it is estimated that as many as 25% of infections in the ICU are hospital-acquired, and that 50% of all antibiotics are used precisely for their treatment. Recognizing the causative agent can be challenging, primarily due to the difficulty of adequate sputum sampling, but also due to the lack of understanding of the epidemiological situation in a particular health facility. [ABSTRACT FROM AUTHOR]

Background: To assess the subjective experience of patients and their parents or relatives about the existing pectus excavatum deformity and to contribute to the definition of indications for surgical treatment of this deformity. Methods: The initial sample of psychosocial characteristics consisted of self‐assessments and observations of patients (and parents) regarding their health, self‐image, health care, possible environmental response to their physical appearance, expectations regarding treatment. A modified version of the original Nuss questionnaire on quality of life was used in the psychological part of the examination. Results: The study included a sample of 58 patients aged 10 to 30 years, and a sample of 58 family members of the patient (parents, relatives). The experience of poor emotional status, withdrawals, and bad self‐image in patients older than 15 years than younger were significant. The tendency for female patients to have a worse experience is pronounced and significant. The largest percentage of parents have an 'indecisive' or 'weakly expressed' attitude towards surgery. Parents at a significantly higher rate show greater concern for female children. Conclusion: A systematic evaluation of the psychosocial perception of patients and their relatives (who will consent for the operation) may be a useful diagnostic assessment before correcting an anterior chest wall malformation. [ABSTRACT FROM AUTHOR]

Scalar quantizer selection for processing a signal with a unit variance is a difficult problem, while both selection and quantizer design for the range of variances is even tougher and to the authors' best knowledge, it is not theoretically solved. Furthermore, performance estimation of various image processing algorithms is unjustifiably neglected and there are only a few analytical models that follow experimental analysis. In this paper, we analyse application of piecewise uniform quantizer with Golomb-Rice coding in modified block truncation coding algorithm for grayscale image compression, propose design improvements and provide a novel analytical model for performance analysis. Besides the nature of input signal, required compression rate and processing delay of the observed system have a strong influence on quantizer design. Consequently, the impact of quantizer range choice is analysed using a discrete designing variance and it was exploited to improve overall quantizer performance, whereas variable-length coding is applied in order to reduce quantizer's fixed bit-rate. The analytical model for performance analysis is proposed by introducing Inverse Gaussian distribution and it is obtained by discussing a number of images, providing general closed-form solutions for peak-signal-to-noise ratio and the total average bit-rate estimation. The proposed quantizer design ensures better performance in comparison to the other similar methods for grayscale image compression, including linear prediction of pixel intensity and edgebased adaptation, whereas analytical model for performance analysis provides matching with the experimental results within the range of 1 dB for PSQNR and 0.2 bpp for the total average bit-rate. [ABSTRACT FROM AUTHOR]

BSIM4 model is not suitable for distortion analysis of circuits with bias point , such as passive mixers and RF switches, due to discontinuities in higher order derivatives. Surface potential based PSP model has continuous derivatives to at least third-order, and is therefore suitable for intermodulation products simulation. This paper presents the case study of BSIM4 to PSP model conversion flow and comparison of active and passive mixers and SPDT RF switch simulation results. Simulation results show good agreement of original BSIM4 and converted PSP models' CV, IV, compression point, conversion loss and noise figure, which validates the conversion flow. The converted model has a correct third-order intermodulation products (IM3) slope of three, allowing the simulation of intermodulation products, which was not possible with the original BSIM4 model. [ABSTRACT FROM AUTHOR]

Speaker recognition is an important classification task, which can be solved using several approaches. Although building a speaker recognition model on a closed set of speakers under neutral speaking conditions is a well-researched task and there are solutions that provide excellent performance, the classification accuracy of developed models significantly decreases when applying them to emotional speech or in the presence of interference. Furthermore, deep models may require a large number of parameters, so constrained solutions are desirable in order to implement them on edge devices in the Internet of Things systems for real-time detection. The aim of this paper is to propose a simple and constrained convolutional neural network for speaker recognition tasks and to examine its robustness for recognition in emotional speech conditions. We examine three quantization methods for developing a constrained network: floating-point eight format, ternary scalar quantization, and binary scalar quantization. The results are demonstrated on the recently recorded SEAC dataset. [ABSTRACT FROM AUTHOR]

In this paper, the influence of a zero and a non-zero boresight pointing errors on the performances of free-space optic transmission over the Málaga atmospheric turbulence channel is considered. Closed form expressions for a zero boresight channel model probability density function, non-zero boresight channel model probability density function, as well as a bit-error rate over a binary phase shift keying modulation transmission are provided. Numerical results for zero and non-zero boresight pointing errors are graphically presented. [ABSTRACT FROM AUTHOR]

Laser welding process is used in many industrial sectors. One of the most important aspects of the laser welding quality refers to the geometrical and mechanical properties of welding joints. In order to develop optimal conditions for the laser welding process it is desirable to know in advance which machining parameters to select. Though there are manuals which recommend specific parameters combinations for the desired laser welding quality it is difficult to cover all possible combinations because of the process nonlinearity. Therefore, in this study the main aim is to establish an algorithm for optimal parameters forecasting of the laser welding process. The algorithm is based on an artificial intelligence approach. The main goal is to forecast the geometrical parameters of the welding joints like front width, front heights, back width and back heights of the welding joints. Experimental process was performed in order to acquire training and testing data of the laser welding process. The obtained results could be of practical importance for engineers in industry. [ABSTRACT FROM AUTHOR]

In this paper, the influence of a zero and a non-zero boresight pointing errors on the performances of free-space optic transmission over the Málaga atmospheric turbulence channel is considered. Closed form expressions for a zero boresight channel model probability density function, non-zero boresight channel model probability density function, as well as a bit-error rate over a binary phase shift keying modulation transmission are provided. Numerical results for zero and non-zero boresight pointing errors are graphically presented. [ABSTRACT FROM AUTHOR]

Background: Locked-in syndrome (LIS) is a condition characterized by quadriplegia and anarthria. The most common cause is a ventral pontine lesion due to atherosclerotic basilar artery disease. Methods: Cases with LIS were prospectively identified among the patients with acute ischemic stroke over 3 years, between 2009 and 2011. Clinical characteristics, topographic localization of lesions, and outcome were determined during the first 6 months from onset of LIS. Results: Our case series consists of 20 patients (mean age 62 ± 10 years; range 46-82). Initially 16 patients had a reduced level of consciousness (mean 3 days; range 1-15). Respiratory disturbance, mainly as impairment of the breathing pattern, was noted in all cases. Five patients died within the first 10 days due to stroke progression or cardiac arrest. In the remaining cases the most frequent causes of death were pulmonary infections and sepsis. Overall mortality in the acute phase of LIS is 75%, and the median survival time is 42 days. There was a statistically significant association between the more extensive parenchymal brain stem lesions and observed mortality. Conclusions: Ischemic LIS is commonly caused by an acute complete occlusion of the basilar artery due to atherosclerotic lesions in intracranial vertebrobasilar vessels. Mortality remains high in the acute phase of the disease. Copyright © 2013 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]