Power spectrum techniques were applied to two time series of wind speed values recorded at the Arctowski Station in order to investigate the influence of turbulent and laminar air flow on the quasi-periodicity of the micro-scale wind structure.

Analysis of harmonic parameters and detection of foreign frequencies in diagnostic signals, which are most often interpreted as fault results, may be problematic because of the spectral leakage effect. When the signal contains only the fundamental frequency and harmonics, it is possible to adjust its spectral resolution to eliminate any distortions for regular frequencies. The paper discusses the influence of resampling distortions on the quality of spectral resolution optimization in diagnostic signals, recorded digitally for objects in a steady state. The method effectiveness is measured with the use of a synthetic signal generated from an analog prototype whose parameters are known. In order to achieve low values of harmonic amplitude errors in the diagnostic signal, a high quality resampling algorithm should be used, therefore the analysis of distortions generated by four popular reasampling methods is performed. Errors are measured for test signals containing different spectral structures. Finally, the results of the test of the analyzed method in practical applications are presented.

Satellite remote sensing provides a synoptic view of the land and a spatial context for measuring drought impacts, which have proved to be a valuable source of spatially continuous data with improved information for monitoring vegetation dynamics. Many studies have focused on detecting drought effects over large areas, given the wide availability of low-resolution images. In this study, however, the objective was to focus on a smaller area (1085 km2) using Landsat ETM+ images (multispectral resolution of 30 m and 15 m panchromatic), and to process very accurate Land Use Land Cover (LULC) classification to determine with great precision the effects of drought in specific classes. The study area was the Tortugas-Tepezata sub watershed (Moctezuma River), located in the state of Hidalgo in central Mexico. The LULC classification was processed using a new method based on available ancillary information plus analysis of three single date satellite images. The newly developed LULC methodology developed produced overall accuracies ranging from 87.88% to 92.42%. Spectral indices for vegetation and soil/vegetation moisture were used to detect anomalies in vegetation development caused by drought; furthermore, the area of water bodies was measured and compared to detect changes in water availability for irrigated crops. The proposed methodology has the potential to be used as a tool to identify, in detail, the effects of drought in rainfed agricultural lands in developing regions, and it can also be used as a mechanism to prevent and provide relief in the event of droughts.

In this article, I will sketch a particular way of thinking about existence in time, the consequence of which would be practicing historiography as a response to the voices of the dead coming from the past. This theoretical conception of history tries to understand history not so much as an unfolding process of succession over time but as some community of the living and the dead. If the voices of the dead, defined in terms of spectrality, are to be active somehow in the present, they cannot be prematurely suppressed by gestures of closing the past understood as blocking the transmission of these voices to the future. After analyzing the problem of false closures in history, I am trying to understand spectrality that would combine both past and present activity. The article aims to propose tasks for a historiography that would consist in regaining in con-temporary culture the ability to hear the voice, the gaze, and the expectations coming from the past, present in various forms which can be grasped by an encompassing notion of spectrality. Reflection on spectrality brings us closer to the meaning of the concept of counter‑time.

Background: Autonomic dysfunction, impaired baroreflex sensitivity (BRS), and deranged circulatory homeostasis have been observed in chronic hyperglycemia and found to be associated with increased cardiovascular morbidity and mortality. However, the acute effects of hyperglycemia in healthy subjects have been rarely studied. The present study explores the effect of acute hyperglycemia on con-ventional and unconventional parameters of BRS in healthy young adults.
Methods: For the estimation of BRS beat-to-beat blood pressure (BP) and electrocardiogram were recorded in forty-two young, healthy subjects during fasting and at 1hr of the oral glucose load. Analysis of BRS was carried out by sequence and spectral method. Number of UP-, DOWN- and ALL-sequences between ramps of BP and RR-interval were calculated as an unconventional measure of BRS along with the other conventional parameters.
Results: We observed significant alteration of unconventional parameters of autonomic functions [the number of sequences of UP- (p = 0.0039) and ALL-sequences (p = 0.0233) of systolic BP and RR interval; and, UP- (p = 0.0380), DOWN- (p = 0.0417) and ALL-sequences (p = 0.0313) of mean BP and RR- interval] during acute hyperglycemia as compared to the fasting state. However, no significant changes were observed in any of the conventional parameters of BRS during acute hyperglycemia as compared to the fasting state.
Conclusions: Present study concludes that the unconventional parameters of BRS — the number of sequences between the ramp of BP and RR-interval — change significantly during acute hyperglycemia. However, the conventional parameters do not show significant changes during acute hyperglycemia. We may hypothesize that the relatively constant BRS is maintained at the expense of increased oscillations in the ramp of BP and RR-interval.

Two potato cultivars, sprayed and nonsprayed with fungicides, were evaluated to determine the association of late blight (caused by Phytophtora infestans) and radiometric leaf reflectance to disease development. Spectral radiance measurements were taken with Cl MEL CE3132 luminancemeter in the visible (450 nm, 550 nm and 650 nm) and near-infrared (850 nm) range of the electromagnetic spectrum. The measurements were taken at two view zenithal angles.ó.> 0° (at nadir) and o.> 50°. Six vegetative indices based on these measurements were used to detect differences between sprayed and nonsprayed plants. Vegetation indices based on the reflectance measurement enable to distinguish infected potato plants from noninfected plants. Among the vegetation indices used in this studies the best indicators of disease were NlR/RED and ELA!. Results of our study show that for Mila cultivar oblique viewing may be more effective then nadir viewing (perpendicular to the ground surface) for distinguishing between plants infested at different degree.

The possibilities of remote sensing techniques in the field of the Earth surface monitoring and protection specifically for the problems caused by petroleum contaminations, for the mapping of insufficiently plugged and abandoned old oil wells and for the analysis of onshore oil seeps are described. Explained is the methodology for analyzing and detection of potential hydrocarbon contaminations using the Earth observation in the area of interest in Slovakia (Korňa) and in Czech Republic (Nesyt), mainly building and calibrating the spectral library for oil seeps. The acquisition of the in-situ field data (ASD, Cropscan spectroradiometers) for this purpose, the successful building and verification of hydrocarbon spectral library, the application of hydrocarbon indexes and use of shift in red-edge part of electromagnetic spectra, the spectral analysis of input data are clarified in the paper. Described is approach which could innovate the routine methods for investigating the occurrence of hydrocarbons and can assist during the mapping and locating the potential oil seep sites. Important outcome is the successful establishment of a spectral library (database with calibration data) suitable for further application in data classification for identifying the occurrence of hydrocarbons.

In Western music culture instruments have been developed according to unique instrument acoustical features based on types of excitation, resonance, and radiation. These include the woodwind, brass, bowed and plucked string, and percussion families of instruments. On the other hand, instrument performance depends on musical training, and music listening depends on perception of instrument output. Since musical signals are easier to understand in the frequency domain than the time domain, much effort has been made to perform spectral analysis and extract salient parameters, such as spectral centroids, in order to create simplified synthesis models for musical instrument sound synthesis. Moreover, perceptual tests have been made to determine the relative importance of various parameters, such as spectral centroid variation, spectral incoherence, and spectral irregularity. It turns out that the importance of particular parameters depends on both their strengths within musical sounds as well as the robustness of their effect on perception. Methods that the author and his colleagues have used to explore timbre perception are: 1) discrimination of parameter reduction or elimination; 2) dissimilarity judgments together with multidimensional scaling; 3) informal listening to sound morphing examples. This paper discusses ramifications of this work for sound synthesis and timbre transposition.

The paper presents results of research on an influence of listening fatigue on the detection of changes in spectrum and envelope of musical samples. The experiment was carried out under conditions which normally exist in a studio or on the stage when sound material is recorded and/or mixed. The equivalent level of presented sound samples is usually 90 dB and this is an average value of sound level existing in control room at various recording activities. Such musical material may be treated as a noise so Temporary Threshold Shift phenomenon may occur after several sessions and this may lead to a listening fatigue effect. Fourteen subjects participated in the first part of the experiment and all of them have the normal hearing thresholds. The stimuli contained the musical material with introduced changes in sound spectrum up to ±6 dB in low (100 Hz), middle (1 kHz) and high frequency (10 kHz) octave bands. In the second part of research five subjects listened to musical samples with introduced envelope changes up to ±6 dB in interval of 1 s. The time of loud music exposure was 60, 90 and 120 minutes and this material was completely different from the tested samples. It turned out that listening to the music with an Leq = 90 dB for 1 hour influences the hearing thresholds for middle frequency region (about 1-2 kHz) and this has been reflected in a perception of spectral changes. The perceived peaks/notches of 3 dB have the detection ability at 70% and the changes of low and high ranges of spectrum were perceived at the similar level. After the longer exposure, the thresholds shifted up to 4.5 dB for the all investigated stimuli. It has been also found that hearing fatigue after 1 hour of a listening influences the perception of envelope which gets worse of 2 dB in comparison to the fresh-ear listening. When time of listening to the loud music increases, the changes in envelopes which can be detected rise to the value of 6 dB after 90-minutes exposure and it does not increase with further prolongation of listening time.

The Gaussian mixture model (GMM) method is popular and efficient for voice conversion (VC), but it is often subject to overfitting. In this paper, the principal component regression (PCR) method is adopted for the spectral mapping between source speech and target speech, and the numbers of principal components are adjusted properly to prevent the overfitting. Then, in order to better model the nonlinear relationships between the source speech and target speech, the kernel principal component regression (KPCR) method is also proposed. Moreover, a KPCR combined with GMM method is further proposed to improve the accuracy of conversion. In addition, the discontinuity and oversmoothing problems of the traditional GMM method are also addressed. On the one hand, in order to solve the discontinuity problem, the adaptive median filter is adopted to smooth the posterior probabilities. On the other hand, the two mixture components with higher posterior probabilities for each frame are chosen for VC to reduce the oversmoothing problem. Finally, the objective and subjective experiments are carried out, and the results demonstrate that the proposed approach shows greatly better performance than the GMM method. In the objective tests, the proposed method shows lower cepstral distances and higher identification rates than the GMM method. While in the subjective tests, the proposed method obtains higher scores of preference and perceptual quality.

Spectral remote sensing is a very popular method in atmospheric monitoring. The paper presents an approach that involves mid-infrared spectral measurements of combustion processes. The dominant feature in this spectral range is CO2 radiation, which is used to determine the maximum temperature of nonluminous flames. Efforts are also made to determine the temperature profile of hot CO2, but they are limited to the laboratory conditions. The paper presents an analysis of the radiation spectrum of a non-uniform-temperature gas environment using a radiative transfer equation. Particularly important are the presented experimental measurements of various stages of the combustion process. They allow for a qualitative description of the physical phenomena involved in the process and therefore permit diagnostics. The next step is determination of a non-uniform-temperature profile based on the spectral radiation intensity with the 8 m optical path length.

Spectrometry, especially spectrophotometry, is getting more and more often the method of choice not only in laboratory analysis of (bio)chemical substances, but also in the off-laboratory identification and testing of physical properties of various products, in particular - of various organic mixtures including food products and ingredients. Specialised spectrophotometers, called spectrophotometric analysers, are designed for such applications. This paper is on the state of the art in the domain of data processing in spectrophotometric analysers of food (including beverages). The following issues are covered: methodological background of food analysis, physical and metrological principles of spectrophotometry, the role of measurement data processing in spectrophotometry. General considerations are illustrated with examples, predominantly related to wine and olive oil analysis.

To improve the estimation of active power, the possibility of estimating the amplitude square of a signal component using the interpolation of the squared amplitude discrete Fourier transform (DFT) coefficients is presented. As with an energy-based approach, the amplitude square can be estimated with the squared amplitude DFT coefficients around the component peak and a suitable interpolation algorithm. The use of the Hann window, for which the frequency spectrum is well known, and the three largest local amplitude DFT coefficients gives lower systematic errors in squared interpolated approach or in better interpolated squared approach than the energy-based approach, although the frequency has to be estimated in the first step. All investigated algorithms have almost the same noise propagation and the standard deviations are about two times larger than the Cramér-Rao lower bound.

In this paper, a filtering stage based on employing a Savitzky-Golay (SG) filter is proposed to be used in the spectrum sensing phase of a Cognitive Radio (CR) communication paradigm for Vehicular Dynamic Spectrum Access (VDSA). It is used to smooth the acquired spectra, which constitute the input for a spectrum sensing algorithm. The sensing phase is necessary, since VDSA is based on an opportunistic approach to the spectral resource, and the opportunities are represented by the user-free spectrum zones, to be detected through the sensing phase. Each filter typology presents peculiarities in terms of its computational cost, de-noising ability and signal shape reconstruction. The SG filtering properties are compared with those of the linear Moving Average (MA) filter, widely used in the CR framework. Important improvements are proposed.

The quality of the supplied power by electricity utilities is regulated and of concern to the end user. Power quality disturbances include interruptions, sags, swells, transients and harmonic distortion. The instruments used to measure these disturbances have to satisfy minimum requirements set by international standards. In this paper, an analysis of multi-harmonic least-squares fitting algorithms applied to total harmonic distortion (THD) estimation is presented. The results from the different least-squares algorithms are compared with the results from the discrete Fourier transform (DFT) algorithm. The algorithms are assessed in the different testing states required by the standards.

Additional motor vibrations are the result of a faulty bearing. They are reflected in the harmonic content of stator currents. The object of the investigation presented in the paper are measurements related to diagnostics of induction motors, especially damages caused to bearings. Due to the fact that the amplitude of the network voltage basic harmonic in the current spectrum is high in comparison with components responsible for damages of bearings, preliminary elimination of this component from the analog current signal has been proposed.

The problem with interpretation of diagnostic measurements in present systems is the difference between measurement results of characteristic frequencies and theoretical calculations.

In the proposed measurement system this problem was solved in such a way that the value of the angular speed and of the supply frequency is calculated on the basis of appropriate components in the very same current spectrum that is further used in the search for diagnostic components.

The paper presents also the measuring system and provides results of the investigations carried out on a motor encumbered with a specially prepared defect.

The paper presents a spectral formulation of surface profile irregularity in a wideband frequency range for roughness, waviness and shape components along the measured length. A unique distribution of roughness and waviness components is proposed, according to the nature of their origination in the course of machining with tools of defined cutting edge, as distinct from standard filtration in measurements of surface irregularities. Differences resulting from both formulations are outlined as well as the method of determining the frequency of component separation for surface roughness and waviness.

Position time series from permanent Global Navigation Satellite System (GNSS) stations are commonly used for estimating secular velocities of discrete points on the Earth’s surface. An understanding of background noise in the GNSS position time series is essential to obtain realistic estimates of velocity uncertainties. The current study focuses on the investigation of background noise in position time series obtained from thirteen permanent GNSS stations located in Nepal Himalaya using the spectral analysis method. The power spectrum of the GNSS position time series has been estimated using the Lomb–Scargle method. The iterative nonlinear Levenberg–Marquardt (LM) algorithm has been applied to estimate the spectral index of the power spectrum. The power spectrum can be described by white noise in the high frequency zone and power law noise in the lower frequency zone. The mean and the standard deviation of the estimated spectral indices are −1.46±0.14,−1.39±0.16 and −1.53±0.07 for north, east and vertical components, respectively. On average, the power law noise extends up to a period of ca. 21 days. For a shorter period, i.e. less than ca. 21 days, the spectra are white. The spectral index corresponding to random walk noise (ca. –2) is obtained for a site located above the base of a seismogenic zone which can be due to the combined effect of tectonic and nontectonic factors rather than a spurious monumental motion. Overall, the usefulness of investigating the background noise in the GNSS position time series is discussed.

On fifth-generation wireless networks, a potential massive MIMO system is used to meet the ever-increasing request for high-traffic data rates, high-resolution streaming media, and cognitive communication. In order to boost the trade-off between energy efficiency (EE), spectral efficiency (SE), and throughput in wireless 5G networks, massive MIMO systems are essential. This paper proposes a strategy for EE 5G optimization utilizing massive MIMO technology. The massive MIMO system architecture would enhance the trade-off between throughput and EE at the optimum number of working antennas. Moreover, the EE-SE tradeoff is adjusted for downlink and uplink massive MIMO systems employing linear precoding techniques such as Multiple -Minimum Mean Square Error (M-MMSE), Regularized Zero Forcing (RZF), Zero Forcing (ZF), and Maximum Ratio (MR). Throughput is increased by adding more antennas at the optimum EE, according to the analysis of simulation findings. Next, utilizing M MMSE instead of RZF and ZF, the suggested trading strategy is enhanced and optimized. The results indicate that M-MMSE provides the best tradeoff between EE and throughput at the determined optimal ratio between active antennas and active users equipment’s (UE).

Multicarrier modulation (MCM) based schemes have been a major contributing factor in revolutionizing cellular networks due to their ability to overcome fading. One of the popular scheme orthogonal frequency division multiple access (OFDMA), having been part of 4G, is also adapted as part of 5G enhanced mobile broadband (eMBB). Though it has several advantages, spectral efficiency (SE) and peak to average power ratio (PAPR) have been two major concerns which have attracted lot of attention resulting in proposals of several other MCM schemes. But most of these studies have treated the two issues independently. This paper in particular studies the subcarrier filtering approach to improve the spectral efficiency of MCM scheme and its impact on the overall PAPR of such schemes. The analysis shows that the PAPR improvement is also achieved by such filters meant for spectral confinement and the simulation results validate the same provoking.

This paper takes a look at the state-of-the-art solutions in the field of spectral imaging systems by way of application examples. It is based on a comparison of currently used systems and the challenges they face, especially in the field of high-altitude imaging and satellite imaging, are discussed. Based on our own experience, an example of hyperspectral data processing is presented. The article also discusses how modern algorithms can help in understanding the data that such images can provide.

The behaviour of energy levels and optical spectra of a charged particle (electron or hole) confined within a potential well of ellipsoidal shape is investigated as a function of the shape-anisotropy parameter. If two energy levels of the same symmetry intersect in a perturbation-theory approximation, they move apart on direct diagonalization of the appropriate Hamiltonian. The intersection of the energy levels leads to a discontinuity of the corresponding dipole-moment matrix element. The discontinuity of matrix elements is not reflected in the behaviour of transition probabilities which are continuous functions of the shape-anisotropy parameter. The profiles of a spectral line emitted or absorbed by an ensemble of ellipsoidally shaped nanoparticles with a Gaussian distribution of size are calculated and discussed.

Solar radiation reflectance was analysed to characterize Arctic ornithogenic tundra developing in the vicinity of large breeding colony of Brunnich‘s guillemots Uria lomvia and kittiwakes Rissa tridactyla at the foot of Gnĺlberget cliff (Hornsund, SW Spitsbergen). Radiometric method was found to be a useful tool for studying structure and functioning of plant formations. We measured reflectance of four wavelengths: 554 nm (YG), 655 nm (RED), 870 nm (NIR) and 1650 nm (SWIR) at 10 plots situated along the transect running from the colony to the sea. Moreover, data of plant community character, species quantitative composition as well as total biomass were collected to relate these parameters with the spectral values. The results showed that radiometric data characterized vegetation well enough to recognize the same plant communities on the basis of spectral reflectance as distinguished with traditional phytosociological methods.

The paper presents the results of research on commercial photovoltaic cells made of crystalline silicon. In particular, the focus was on the description of the elaborated by the authors measuring system with measurements methodology used for assessment of the influence of temperature on spectral characteristics of the tested cells, describing the dependence of the current sensitivity (spectral response, responsivity) and the external quantum efficiency on the wavelength of optical radiation. The investigations carried out in the proposed test system made it possible to evaluate the properties of the cells in the conditions similar to the operating conditions.