Amateur radio sensing technique using a combination of energy detection and waveform classification

<p>A critical problem in spectrum sensing is to create a detection algorithm and test statistics. The existing approaches employ the energy level of each channel of interest. However, this feature cannot accurately characterize the actual application of public amateur radio. The transmitted signal is not continuous and may consist only of a carrier frequency without information. This paper proposes a novel energy detection and waveform feature classification (EDWC) algorithm to detect speech signals in public frequency bands based on energy detection and supervised machine learning. The energy level, descriptive statistics, and spectral measurements of radio channels are treated as feature vectors and classifiers to determine whether the signal is speech or noise. The algorithm is validated using actual frequency modulation (FM) broadcasting and public amateur signals. The proposed EDWC algorithm's performance is evaluated in terms of training duration, classification time, and receiver operating characteristic. The simulation and experimental outcomes show that the EDWC can distinguish and classify waveform characteristics for spectrum sensing purposes, particularly for the public amateur use case. The novel technical results can detect and classify public radio frequency signals as voice signals for speech communication or just noise, which is essential and can be applied in security aspects.</p>

Preparation of N-TiO2/SiO2 composites by solvothermal method and their photocatalytic properties

In order to improve the visible light catalytic activity of titanium dioxide (TiO2) and ensure its long-term stability on the surface of concrete, an N-TiO2/SiO2 composite was prepared using tetrabutyl titanate, nitric acid, and modified SiO2 nanospheres as the precursors by a solvothermal method. The effect of nitric acid on the phase composition, morphology and photoelectric properties of the synthesized photocatalytic composites was systematically studied by various characterization methods. The results show that the optimum nitric acid/butyl titanate volume ratio is 1/6. The nitrogen-doped TiO2 nanoparticles were uniformly dispersed on the surface of spherical SiO2 with a diameter of 200 nm. The degradation rate of simulated pollutants (RhB) with pH 5 and 7 exceeded 95% within 30 minutes and the catalytic effect remained excellent after five repetitions without much weakening. The excellent visible photocatalytic performance can be attributed to the doping of N replacing part of the oxygen atoms in TiO2, forming the energy level of N 2p at the O 2p energy level and reducing the TiO2 energy band gap to 2.99 eV. At the same time, the better dispersion of N-TiO2/SiO2 prepared by this new synthesis method also plays an important role in the improvement of visible light photocatalytic activity.

Immune Cells vs. Cancer Cells: A Microscopic Energy Battle

Like living organisms, cancer cells require energy to survive and interact with their environment. Recently, investigators demonstrated that cancer cells can hijack mitochondria from immune cells. This behavior sheds light on a pivotal piece in the puzzle of cancer, the &lsquo;dependence&rsquo;. This article illustrates how new, functional mitochondria help cancer cells to survive in the harsh tumor microenvironment, evade immune cells, and improve their malignancy. Finally, we will discuss how blocking the routes supplying energy for cancer cells can improve the treatment outcomes of radiotherapy, chemotherapy, and immunotherapy. This article provides a new theory in oncology, the &lsquo;energy battle&rsquo; between cancer and immune cells. It alludes each party with a higher energy level can be the winner. This theory explains cancer biogenesis and provides novel insights to improve treatment outcomes.

Metal oxide charge transfer complex for effective energy band tailoring in multilayer optoelectronics

Metal oxides are intensively used for multilayered optoelectronic devices such as organic light-emitting diodes (OLEDs). Many approaches have been explored to improve device performance by engineering electrical properties. However, conventional methods cannot enable both energy level manipulation and conductivity enhancement for achieving optimum energy band configurations. Here, we introduce a metal oxide charge transfer complex (NiO:MoO3-complex), which is composed of few-nm-size MoO3 domains embedded in NiO matrices, as a highly tunable carrier injection material. Charge transfer at the finely dispersed interfaces of NiO and MoO3 throughout the entire film enables effective energy level modulation over a wide work function range of 4.47 – 6.34 eV along with enhanced electrical conductivity. The high performance of NiO:MoO3-complex is confirmed by achieving 189% improved current efficiency compared to that of MoO3-based green OLEDs and also an external quantum efficiency of 17% when applied to blue OLEDs, which is superior to 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile-based conventional devices.

On-Demand Charging Management Model and Its Optimization for Wireless Renewable Sensor Networks

Nowadays, wireless energy transfer (WET) is a new strategy that has the potential to essentially resolve energy and lifespan issues in a wireless sensor network (WSN). We investigate the process of a wireless energy transfer-based wireless sensor network via a wireless mobile charging device (WMCD) and develop a periodic charging scheme to keep the network operative. This paper aims to reduce the overall system energy consumption and total distance traveled, and increase the ratio of charging device vacation time. We propose an energy renewable management system based on particle swarm optimization (ERMS-PSO) to achieve energy savings based on an investigation of the total energy consumption. In this new strategy, we introduce two sets of energies called emin (minimum energy level) and ethresh (threshold energy level). When the first node reaches the emin, it will inform the base station, which will calculate all nodes that fall under ethresh and send a WMCD to charge them in one cycle. These settled energy levels help to manage when a sensor node needs to be charged before reaching the general minimum energy in the node and will help the network to operate for a long time without failing. In contrast to previous schemes in which the wireless mobile charging device visited and charged all nodes for each cycle, in our strategy, the charging device should visit only a few nodes that use more energy than others. Mathematical outcomes demonstrate that our proposed strategy can considerably reduce the total energy consumption and distance traveled by the charging device and increase its vacation time ratio while retaining performance, and ERMS-PSO is more practical for real-world networks because it can keep the network operational with less complexity than other schemes.

The Effect of Energy Level of Transport Layer on the Performance of Ambient Air Prepared Perovskite Solar Cell: A SCAPS-1D Simulation Study

The perovskite solar cell (PSC) as an emerging and promising type has been extensively studied. In this study, a model for a PSC prepared in ambient air was established by using SCAPS-1D. After that, it was further analyzed through varying the defect density of the perovskite absorber layer (Nt), the thin film thickness and energy-level matching between the electron transport layer (ETL), the perovskite absorber layer and the hole transport layer (HTL), for a better understanding of the carrier features. The Nt varied from 1.000 × 1011 to 1.000 × 1017 cm−3. The performance of the solar cell is promoted with improved Nt. When Nt is at 1.000 × 1015 cm−3, the carrier diffusion length reaches μm, and the carrier lifetime comes to 200 nm. The thickness of the absorber layer was changed from 200 to 600 nm. It is shown that the absorber layer could be prepared thinner for reducing carrier recombination when at high Nt. The thickness effect of ETL and HTL is weakened, since Nt dominates the solar cell performance. The effect of the affinity of ETL (3.4–4.3 eV) and HTL (2.0–2.7 eV), together with three energy-level matching situations “ETL(4.2)+HTL(2.5)”, “ETL(4.0)+HTL(2.2)” and “ETL(4.0)+HTL(2.5)” on the performance of the solar cell were analyzed. It was found that the HTL with valence band 0.05 eV lower than that of the perovskite absorber layer could have a blocking effect that reduced carrier recombination. The effect of energy-level matching becomes more important with improved Nt. Energy-level matching between the ETL and perovskite absorber layer turns out counterbalance characteristic on Jsc and Voc, and the “ETL(4.0)+HTL(2.5)” case can result in solar cell with Jsc of 27.58 mA/cm2, Voc of 1.0713 V, FF of 66.02% and efficiency of 19.51%. The findings would be very useful for fabricating high-efficiency and low-cost PSC by a large-scale ambient air route.

Возбуждение и ионизация частицы в одномерной потенциальной яме нулевого радиуса предельно коротким световым импульсом

The Migdal sudden perturbation approximation is used to solve the problem of excitation and ionization particles in a one-dimensional potential of zero radius with an extremely short pulse. There is has only one energy level in such a one-dimensional the delta-shaped potential well. It is shown that for pulse durations shorter than the characteristic period of oscillations of the wave function of the particle in the bound state, the population of the level (and the probability of ionization) is determined by the ratio of the electric the area of ​​the pulse to the characteristic “scale” of the area inversely proportional to the area of ​​localization of the particle in a bound state.