In the paper the idea of rational polynomial windows optimised towards low level of Fourier spectrum's sidelobes is presented. A relevant advantage of the polynomial windows family and their modifications is their ability to easily change their properties changing only the values of the polynomial coefficients. The obtained frequency characteristics demonstrate better properties of proposed rational Windows than their standard polynomial equivalents requiring only the additional division operation. Such approach does not increase the computational complexity in significant way and the great advantage of polynomial windows which is their low computational complexity is preserved.

In this article is revealed the systems of a good delivery witch implement unmanned aerial vehicles during providing the service. the one channel systems of a goods delivery are a goal of this research work. the close analysing of their functional features, the classification, the types and parameters of different systems from this band are presented. in addition, the modelling of the different types of the one channel systems of goods delivery are has done.

Quality of energy produced in renewable energy systems has to be at the high level specified by respective standards and directives. One of the most important factors affecting quality is the estimation accuracy of grid signal parameters. This paper presents a method of a very fast and accurate amplitude and phase grid signal estimation using the Fast Fourier Transform procedure and maximum decay side-lobes windows. The most important features of the method are elimination of the impact associated with the conjugate’s component on the results and its straightforward implementation. Moreover, the measurement time is very short ‒ even far less than one period of the grid signal. The influence of harmonics on the results is reduced by using a bandpass pre-filter. Even using a 40 dB FIR pre-filter for the grid signal with THD ≈ 38%, SNR ≈ 53 dB and a 20‒30% slow decay exponential drift the maximum estimation errors in a real-time DSP system for 512 samples are approximately 1% for the amplitude and approximately 8.5・10‒2 rad for the phase, respectively. The errors are smaller by several orders of magnitude with using more accurate pre-filters.

The article presents reviews of the European Union regulation on reporting formalities for ships entering the EU ports. It also analyses IMO regulation concerning that matter. Finally, the author exposes the differences between both legal systems and weaknesses of the solutions adopted. In the second part of the article the author discusses the Polish way of the reporting formalities system’s implementation. On the basis of a legal analysis as well as practice of the maritime authorities in Poland, the author finds that the Polish regulations seem to be exemplary.

Combine harvesters are the source a large amount of noise in agriculture. Depending on different working conditions, the noise of such machines can have a significant effect on the hearing condition of drivers. Therefore, it is highly important to study the noise signals caused by these machines and find solutions for reducing the produced noise. The present study was carried out is order to obtain the fractal dimension (FD) of the noise signals in Sampo and John Deere combine harvesters in different operational conditions. The noise signals of the combines were recorded with different engine speeds, operational conditions, gear states, and locations. Four methods of direct estimations of the FD of the waveform in the time domain with three sliding windows with lengths of 50, 100, and 200 ms were employed. The results showed that the Fractal Dimension/Sound Pressure Level [dB] in John Deere and Sampo combines varied in the ranges of 1.44/96.8 to 1.57/103.2 and 1.23/92.3 to 1.51/104.1, respectively. The cabins of Sampo and John Deere combines reduced and enhanced these amounts, respectively. With an increase in the length of the sliding windows and the engine speed of the combines, the amount of FD increased. In other words, the size of the suitable window depends on the extraction method of calculating the FD. The results also showed that the type of the gearbox used in the combines could have a tangible effect on the trend of changes in the FD.

The solar photovoltaic technology is one of the renewable technologies with the potential to shape a future-proof, reliable, scalable and affordable electricity system. It is important to provide better resources for any upcoming technology. CdS/CdTe thin films have long been considered as one enticing option for reliable and cost-effective solar cells to be developed. N-type CdS as a transparent window layer in heterojunction structures is one of the best choices for CdTe cells. In a solar cell structure, window layer material plays a very crucial role to improve its performance. For this reason, this review focuses on the basic and significant aspects such as importance of the window layer thickness, degradation effect, use of nano-wire arrays, and an ammonia-free process to deposit the window layer. Also, an attempt has been made to analyze various processes improving window layer properties. Necessary discussions have been included to review the impact of solar cell parameters on the above aspects. It is anticipated that this review article will fulfill the requirement of knowledge to be used in the fabrication of CdS/CdTe solar cells.

The most challenging in speech enhancement technique is tracking non-stationary noises for long speech segments and low Signal-to-Noise Ratio (SNR). Different speech enhancement techniques have been proposed but, those techniques were inaccurate in tracking highly non-stationary noises. As a result, Empirical Mode Decomposition and Hurst-based (EMDH) approach is proposed to enhance the signals corrupted by non-stationary acoustic noises. Hurst exponent statistics was adopted for identifying and selecting the set of Intrinsic Mode Functions (IMF) that are most affected by the noise components. Moreover, the speech signal was reconstructed by considering the least corrupted IMF. Though it increases SNR, the time and resource consumption were high. Also, it requires a significant improvement under nonstationary noise scenario. Hence, in this article, EMDH approach is enhanced by using Sliding Window (SW) technique. In this SWEMDH approach, the computation of EMD is performed based on the small and sliding window along with the time axis. The sliding window depends on the signal frequency band. The possible discontinuities in IMF between windows are prevented by the total number of modes and the number of sifting iterations that should be set a priori. For each module, the number of sifting iterations is determined by decomposition of many signal windows by standard algorithm and calculating the average number of sifting steps for each module. Based on this approach, the time complexity is reduced significantly with suitable quality of decomposition. Finally, the experimental results show the considerable improvements in speech enhancement under non-stationary noise environments.

We describe a new method to separate ballistic from the scattered photons for optical tissue characterization. It is based on the hypothesis that the scattered photons acquire a phase delay. The photons passing through the sample without scattering or absorption preserve their coherence so they may participate in interference. We implement a Mach−Zehnder experimental setup where the ballistic photons pass through the sample with the delay caused uniquely by the sample indices of refraction. We incorporate a movable mirror on the piezoelectric actuator in the sample arm to detect the amplitude of the modulation term. We present the theory that predicts the path−integrated (or total) concentration of the scattering and absorption centres. The proposed technique may characterize samples with transmission attenuation of ballistic photons by a factor of 10^-14.

Irreversibility analysis was investigated by using refrigerants R22, R407A, and R407C in window type air conditioner system. The experimental study was conducted at various ambient temperatures and air volumetric flow rates to determine the parameters that cause the energy degradation of the system. The irreversibility was compared with respect to volumetric flow rates of the air passing through evaporator (14.15, 12.74, and 10.618 m3/min) and different ambient temperatures (ranging from 28 ◦C to 39 ◦C dry bulb. Results show that the total irreversibility increases with refrigerant mass flow rate and ambient temperature for the three refrigerants. Additionally, R22 shows the highest irreversibility in low ambient temperature (28 ◦C to 30 ◦C) while R407A shows the lowest one with ambient temperature ranging from 30 ◦C to 36 ◦C. Both tested refrigerants are very good replacement for R22 in terms of irreversibility and energy analysis and these results are more remarkable with R407A.

An overview of our recent developments, regarding “water-window” soft X-ray (SXR) microscopy based on a laser-plasma double stream gas puff target sources is presented. The work, presented herein, describes two approaches to SXR microscopy. The first one is a low spatial resolution, achromatic SXR microscopy, employing Wolter type-I objective. The second one is a nanometer spatial resolution SXR microscopy, with the use of a Fresnel zone plate objective, for imaging various objects with quasimonochromatic light, emitted from a double stream gas puff target based short wavelength source. The developments regarding both systems are presented, as well as the possible applications, for which the SXR microscope was already employed. Such compact, table-top size, laboratory type microscopy setups may be employed in the near future for complementary-like studies to other, often used, microscopy techniques.