UWB System Performance Improvement Using Smart Interference Rejection Filter

In this paper we proposed a smart interference rejection filter in TH-PPM UWB system, which improves the system\'s error probability for an order of magnitude in case of high power OFDM interference. The smart filter is based on an adaptive transversal filter. Based on the fulfillment of certain conditions, the filter activates or deactivates some parts of it

Effects of Imperfect Reference Signal Recovery on Performance of SC and SSC Receivers over Generalized Fading Channels

This paper presents the study of the effects of imperfect reference signal recovery on the bit error rate (BER) performance of dual-branch switch-and-stay combining (SSC) and multibranch selection combining (SC) receivers in a generalized - fading channel. The average BER of binary and quaternary phase shift keying (BPSK and QPSK) is derived under the assumption that the reference carrier signal is extracted from the received modulated signal. For SSC receiver the optimal switching threshold (in a minimum BER sense) is numerically evaluated. Hereby we determine and discuss the simultaneous influence of the average signal-to-noise ratio (SNR) per bit, fading severity, product phase-locked loop (PLL) bandwidthbit duration (B_LT_b), switching threshold of SSC and diversity order of SC on BER performance. The influence of B_LT_b in different channel conditions and modulation formats is pointed out. The numerical results are confirmed by computer simulations

Relativistic ionization-rescattering with tailored laser pulses

The interaction of relativistically strong tailored laser pulses with an atomic system is considered. Due to a special tailoring of the laser pulse, the suppression of the relativistic drift of the ionized electron and a dramatic enhancement of the rescattering probability is shown to be achievable. The high harmonic generation rate in the relativistic regime is calculated and shown to be increased by several orders of magnitude compared to the case of conventional laser pulses. The energies of the revisiting electron at the atomic core can approach the MeV domain, thus rendering hard x-ray harmonics and nuclear reactions with single atoms feasible

The Effect of Feeding Programmes on Broiler Performance and Production Efficiency

The goal of the paper was to investigate the effect of feeding programmes with different protein levels on broiler performance and production efficiency. The research was conducted on 600 chicks of Cobb-500 and Ross-308 provenience, previously divided into four groups (by feeding treatments). The groups (treatments) differed in the type of mixture given in the starter period. The feeding programmes were, as follows: T1 (control group) – 23% protein mixture (Day 1 to Day 21); T2 - 23% protein mixture (Day 1 to Day 14), and 20% protein mixture (Day 14 to Day 21); T3 – 23% protein mixture (Day 1 to Day 7), and 20% protein mixture (Day 7 to Day 21); T4 - 20% protein mixture (Day 1 to Day 21). The chicks were given 20% protein mixture from Day 21 to Day 35, and 18% protein mixture from Day 35 to Day 42. A standard technology for chicken fattening was carried out. Production efficiency was determined by observing the ratio of the total cost and total revenue, i.e. profit per chick. From the value of the European Production Efficiency Factor (EPEF), a summary indicator of production results, the authors came to a conclusion that T1 (control) group of the Cobb-500 and Ross-308 chicks had achieved higher EPEF than the experimental groups, whereby the values of T2 group were similar to the values of T1. The highest profit per chick was found for T1 group of Cobb-500 chicks and for T2 group of Ross-308 chicks. The research showed that a drastic protein reduction in the starter period had resulted in negative tendencies in the chicks of the both genotypes. From the aspect of development of more profitable feeding programmes, further research should therefore focus on T2 feeding programme

Cikada iz grupe Cicadetta montana nova štetočina kupine u Srbiji

Cicada of the Cicadetta montana Scop. (Hemiptera: Cicadidae) complex is a warm-weather insect species. In the last several years, economically important pests have been recorded on blackberries in some regions of Serbia. Damage from cicadas indirectly causes decay of part of the crop. The complexity of control of this pest is also an important indicator of its danger to blackberry production in Serbia. Knowledge of this insect species in the country is currently based on literature. In 2016, attack by this pest was reported by some agricultural extension services in Serbia. The control of this pest is a very complex process. Positive results can be achieved only if all prevention and direct control measures are implemented in a timely manner.Cikada iz kompleksa Cicadetta montana Scop. (Hemiptera: Cicadidae) je toploljubiva insekatska vrsta. U poslednjih nekoliko godina su zabeležene ekonomski značajne štete na kupini u pojedinim regionima Srbije. Štetnost cikade se ogleda u tome što posredno izaziva propadanje dela prinosa. Složenost suzbijanja ove štetočine takođe je značajan pokazatelj opasnosti po proizvodnju kupine kod nas. Trenutno se kod nas o ovoj insekatskoj vrsti zna samo iz literature. U 2016. godini izveštaj o napadu ove štetočine podnele su i pojedine Poljoprivredne savetodavne i stručne službe Srbije. Suzbijanje ove štetočine je veoma komplikovano. Pozitivni rezultati se ne mogu očekivati ukoliko se pravovremeno ne primene sve preventive i direktne mere u suzbijanju pomenute štetočine

Anthropometric characteristics and vertical jump abilities by player position and performance level of junior female volleyball players

Although absolute jump heights should be considered an important factor in judging the performance requirements of volleyball players, limited data is available on age-appropriate categories. The purpose of this study is to determine the differences in specific anthropometric characteristics and jumping performance variables in under 1219 female volleyball players in rela-tion to playing position and performance level. The sample of subjects consisted of 354 players who prepared for the U19 Women\u2019s Volleyball European Championship 2020 (17.4 \ub1 0.8 years, 1.81 \ub1 0.07 m, 67.5 \ub1 7.1 kg). Playing positions analyzed were setters (n = 55), opposites (n = 37), middle blockers (n = 82), outside hitters (n = 137), and liberos (n = 43). The results showed player position differences in every performance level group in variables of body height, spike, and block jump. Observed differences are a consequence of highly specific tasks of different positions in the composition of the team. Players of different performance levels are significantly different, with athletes of higher-ranked teams achieving better results. The acquired data could be useful for the selection and profiling of young volleyball players

Particle physics with a laser-driven positronium atom

A detailed quantum-electrodynamic calculation of muon pair creation in laser-driven electron-positron collisions is presented. The colliding particles stem from a positronium atom exposed to a superintense laser wave of linear polarization, which allows for high luminosity. The threshold laser intensity of this high-energy reaction amounts to a few 10^22 W/cm^2 in the near-infrared frequency range. The muons produced form an ultrarelativistic, strongly collimated beam, which is explicable in terms of a classical simple-man's model. Our results indicate that the process can be observed at high positronium densities with the help of present-day laser technology.Comment: 4 pages, 3 figure

Structural, morphological and luminescence properties of nanocrystalline up-converting Y1.89Yb0.1Er0.01O3 phosphor particles synthesized through aerosol route

Nanocrystalline up-converting Y₂ O₃Yb³⁺ Er³⁺ phosphor particles were processed in a dispersed system-aerosol, generated ultrasonically at 1.3 MHz from common nitrate precursor solution having fixed ytterbium-to-erbium concentration ratio. The appropriate process parameters: residence time 21 s, carrier gas (air) flow rate 1.6 dm3/min, synthesis temperature 900 °C, led to the formation of un-agglomerated spherical nanostructured secondary particles, having mean particle size of approx 450 nm, composed of primary nanoscaled (20 nm) subunits. In order to reach targeting phase crystallinity, the as-prepared particles were additionally annealed at 1100 °C in air for 12, 24 and 48 h, respectively. Particle structure, morphology and purity were analyzed by X-ray powder diffraction (XRPD), scanning electron microscopy (FESEM/SEM), analytical and high resolution transmission electron microscopy (TEM/HRTEM) in combination with energy dispersive X-ray analysis and Fourier Transform Infrared Spectroscopy (FTIR). All samples crystallized in a cubic bixbyte-structure, space group Ia-3. The crystallite size changed with annealing time from 30 nm in as-prepared sample to 135 nm in sample annealed for 48 h, respectively. Emission spectra were assigned to the following trivalent erbium f–f electronic transitions: ²H₉/₂ → ⁴I₁₅/₂ (blue: 407–420 nm), (²H₁₁/₂̦ ⁴S₃/₂) → ⁴I₁₅/₂ (green: 510–590 nm), and ⁴F₉/₂ → ⁴I₁₅/₂ (red: 640–720 nm). The significant improvement of the emission decay times were observed after thermal treatment and this effect is correlated further with the structural and morphological particles characteristics. For the anneal-ing time of 12 h a quite high emission decay times were achieved (blue: 0.14 ms, green: 0.32 ms and red: 0.39 ms).This research is financially supported through the Project #172035 of the Ministry of Science and Education of the Republic of Serbia. OM especially acknowledge the University Carlos III, Madrid, Spain-Santander Bank Chairs of Excellence program and JSPS 2011/2012 fellowship, Japan.Publicad

Optoelectronic oscillator for 5G wireless networks and beyond

With the development of 5G wireless network and beyond, the wireless carrier frequency will definitely reach millimeter-wave (mm-wave) and even terahertz (THz). As one of the key elements in wireless networks, the local oscillator (LO) needs to operate at mm-wave and THz band with lower phase noise, which becomes a major challenge for commercial LOs. In this article, we investigate the recent developments of the electronic integrated circuit (EIC) oscillator and the optoelectronic oscillator (OEO), and especially investigate the prospect of OEO serving as a qualified LO in the 5G wireless network and beyond. Both the EIC oscillators and OEOs are investigated, including their basic theories of operation, representative techniques and some milestones in applications. Then, we compare the performances between the EIC oscillators and the OEOs in terms of frequency accuracy, phase noise, power consumption and cost. After describing the specific requirements of LO based on the standard of 5G and 6G wireless communication systems, we introduce an injection-locked OEO architecture which can be implemented to distribute and synchronize LOs. The OEO has better phase noise performance at high frequency, which is greatly desired for LO in 5G wireless network and beyond. Besides, the OEO provides an easy and low-loss method to distribute and synchronize mm-wave and THz LOs. Thanks to photonic integrated circuit development, the power consumption and cost of OEO reduce gradually. It is foreseeable that the integrated OEO with lower cost may have a promising prospect in the 5G wireless network and beyond