A New Analytical Accurate Analysis to generate Classical Communication Signals

An investigation was made of a multichannel LiNbO3 waveguide modulator of light in space and time, suitable for processing of analog and digital signals. This modulator had 26 channels and the half-wave control voltage was 4.5 V. A theoretical analysis and an experimental study were made of the functional performance of this modulator depending on the channel interconnections and on the nature of the signals applied to the modulator. The feasibility of processing analog and digital signals was studied.

The paper deals with computing techniques of both active current and power, and their DSP implementation for dynamic compensation of three-phase symmetrical system. The dynamic power active filter using this techniques is determinated for the VAr and higher harmonics compensation of symmetrical nonharmonic/nonlinear loads. The new original concept, which has been used, is the creation of a complex vector of investigated quantities and its hardware decomposition into real- and imaginary components using Clarke orthogonal transform. The analysis can be completed within one sixth of the period for three-phase system (from acquired data of previous sixth), due to six-side symmetry of complex vector. The compensator response to the actual state of the load is then very fast. Discrete Fourier transform and/or numeric solution of active power computation are used for generating new reference data for each successive sixth of the period. The computation-mainly integration can be done by either fast digital signal processor or mixed (analog) signal unit. Simulation experiments in DesignLab environment are presented at the end of the paper.

When creativity is considered as field-specific, creativity that is specific to one field may differ from creativity in another field in terms of necessary knowledge, creative thinking skills, or tendencies. In this context, mathematical creativity is distinguished from general creativity and other field-specific creativity. This chapter discusses how mathematical creativity can be defined. In addition, the concepts of fluency, flexibility, originality, and elaboration, which are important divergent thinking components in the definitions and measurement of mathematical creativity, are explained in a mathematical context. The tools used to measure mathematical creativity are discussed. Among the methods that are effective in the development of general creativity, those that are thought to be effective in the development of mathematical creativity are explained. Open-ended questions and tasks in mathematics are introduced, and their role in developing mathematical creativity is discussed. Finally, suggestions and activity examples for the development of mathematical creativity are presented.

To satisfy the urgent requirements of security for fifth generation (5G) fronthaul network, quantum key distribution (QKD) technique is taken into consideration as a promising way. In this paper, we first propose an architecture for quantum security beyond fifth generation (B5G) fronthaul optical network, which merges facilities of QKD into the architecture of existing 5G fronthaul network, enabling quantum signals to be transmitted with classical signals within the same fiber. Secondly, theoretical model analysis of interference with quantum signals caused by four wave mixing noise is performed. Moreover, the theory of secure key rate calculation under noise interference is introduced. Lastly, the QKD performance in the proposed architecture is evaluated, which leads to the conclusion that even when the quantity of B5G fronthaul optical channels for classical signals reaches up to 12, the secure transmission distance of QKD is still beyond 20km, which satisfies the demand of B5G fronthaul optical network.

Gravitational-wave astronomy has the potential to substantially advance our knowledge of the cosmos, from the most powerful astrophysical engines to the initial stages of our universe. Gravitational waves also carry information about the nature of black holes. Here we investigate the potential of gravitational-wave detectors to test a proposal by Bekenstein and Mukhanov that the area of black hole horizons is quantized in units of the Planck area. Our results indicate that this quantization could have a potentially observable effect on the classical gravitational wave signals received by detectors. In particular, we find distorted gravitational-wave “echoes” in the post-merger waveform describing the inspiral and merger of two black holes. These echoes have a specific frequency content that is characteristic of black hole horizon area quantization.

The labour market is usually associated with phenomena such as unemployment, employment and professional activity/inactivity. The ways in which these categories are shaped depend on various factors of an economic, social and technological nature. It is impossible to disagree with the statement that the contemporary labour market – local, national, and global – is undergoing dynamic changes. In the public debate, the themes of flexicurity, flexible forms of employment, reconciling professional work with private life, and lifelong learning appear more frequently. They cause heated discussions and often also controversies, since their impact on the situation of workers and employers in the labour market is increasing. Observing the trends in the world economy and the global labour market, it can be argued that employment becomes a privilege.Due to the reasons mentioned above, in the paper, issues which relate to ‘incomplete’ employment are discussed. Theoretical considerations are focused on the terminological and methodological problems related to the interpretation of the concept of underemployment both in the Polish and foreign literature. Furthermore, the relationships between the phenomenon of underemployment and the concept of employment flexibility and security are presented, since they are extremely important from the perspective of the contemporary labour market. The theoretical analysis is complemented by a statistical analysis of empirical data that illustrates the current scale of the phenomenon of underemployment in the labour market in Poland compared to other European Union member states (EU-28). The article adopts the research thesis that in Poland there is a problem of ‘incomplete’ employment. Therefore, the aim of this paper is to attempt to identify the scale of this phenomenon on the Polish labour market. Implementation of this objective will be possible thanks to the study of national and foreign literature and a conducted statistical analysis of selected indicators of the labour market in the context of this phenomenon, obtained from the database of the European Statistical Office (Eurostat).

Research on polarization insensitive AOWC system for 40Gbps 16QAM-OFDM based on wide optical comb generation self-pumping structure

Incorporating single photon links used for quantum communication applications like quantum key distribution is a challenging task. Direct contamination from the strong classical signal and induced Raman scattering easily obscures the weak quantum signal. Generating entangled photons in the O-band might allow the coexistence of classical and quantum signals. We present results demonstrating the feasibility of transmitting entangled photons and strong classical communication signals over the same fiber.

Over the past few decades, wireless sensor networks have been widely used in the field of structure health monitoring of civil, mechanical, and aerospace systems. Currently, most wireless sensor networks are battery powered and it is costly and unsustainable for maintenance because of the requirement for frequent battery replacements. As an attempt to address such issue, this paper theoretically and experimentally studies a compression-based piezoelectric energy harvester, which is suitable for the low-frequency and large-force working environments, such as in civil and transportation infrastructure applications. The proposed energy harvester employs the piezoelectric structure constructed in multilayer stack configuration to convert ambient vibrations into electrical energy. Based on the linear theory of piezoelectricity, the two-degree-of-freedom electromechanical models of the proposed energy harvester were developed to characterize its performance in generating electrical energy under external excitations. Exact closed-form expressions of the electromechanical models have been derived to analyze the maximum harvested power and the optimal resistance. The theoretical analyses were validated through several experiments for a test prototype under harmonic excitations. The test results exhibit very good agreement with the analytical analyses and numerical simulations for a range of resistive loads and input excitation levels.

The space–time distribution characteristics of the air-gap magnetic field (AGMF) determine the electromagnetic performance of the motor. This article studies the influence of the inter-turn fault (ITF) on space and time harmonics of the AGMF, and the relevant fault characteristics are obtained through analysis and experiments. First, a theoretical analysis is deduced to compare the components of AGMF before and after the fault, and all space and time harmonics are obtained. Then, according to the parameters of the prototype, the distortion and components of space and time harmonics are analyzed. Also, the influence of rotor slot harmonics is considered to analyze the variations of time harmonics. Finally, a detection wire method that can directly measure the AGMF is proposed, and the spectrum results of the measured signals prove the correctness of the research in this article. A fault feature can be extracted based on the frequency band analysis, and it is not affected by load variations. The results obtained through analytical analysis, simulation, and experiment further improve the AGMF research of induction motors with ITF.

Nonlinear elastoplastic behavior induced by multiwalled carbon nanotubes in the compatibilized low density polyethylene/poly(methyl hydrogen siloxane)-grafted perlite nanocomposites

Methods involved in the treatment of four representative pharmaceuticals in hospital wastewater using sonochemical and biological processes

Realizing long-distance quantum key distribution (QKD) in fiber channel where classical optical communications and quantum signals are multiplexed by their different wavelengths has attracted considerable attentions. The achievable secure distance of commonly-used Bennet-Brassard 1984 (BB84) protocol is lowered severely due to inevitable crosstalk from classical optical pulses. Unlike conventional quantum key distribution (QKD) protocols, round-robin differential-phase-shift (RRDPS) QKD protocol has a high tolerance for noise, since the potential information leakage in this protocol can be bounded without monitoring signal disturbance. Thus, it may be a promising protocol under noisy channel. In this work, we investigate the performance, e.g., achievable secure distance of RRPDS protocol, when crosstalk from classical communication is considered. Surprisingly, we find that RRPDS only has quite limited advantage over BB84 protocol when optical misalignment of QKD system is serious. If misalignment is trivial, BB84 can even outperform RRDPS protocol.

Compressive sensing (CS) is a theory about that one may achieve a nearly exact signal reconstruction from the fewer samples, if the signal is sparse or compressible under some basis. The reconstruction of signal can be obtained by solving a convex program, which is equivalent to a LASSO problem with l1-formulation. In this paper, we propose a stage-wise fast LASSO (StF-LASSO) algorithm for the image reconstruction from CS. It uses an insensitive Huber loss function to the objective function of LASSO, and iteratively builds the decision function and updates the parameters by introducing a stagewise fast learning strategy. Simulation studies in the CS reconstruction of the natural images and SAR images widely applied in practice demonstrate that the good reconstruction performance both in evaluation indexes and visual effect can be achieved by StF-LASSO with the fast recovered speed among the algorithms which have been implemented in our simulations in most of the cases. Theoretical analysis and experiments show that StF-LASSO is a CS reconstruction algorithm with the low complexity and stability.

Aiming at the problem of quantitative inertia evaluation of a new energy electric power system, the system inertia constant tracking method based on system identification is studied. The method is divided into two categories: non-recursive algorithm and recursive algorithm. The non-recursive algorithm uses a batch of data for batch processing to obtain the estimated value of the identification model parameters. The recursive algorithm is based on the estimated value of the model parameter at the previous moment and corrects the estimated value based on the new data currently obtained. From the perspective of the identification principle, the difference and internal relationship between the two in terms of calculation storage and identification speed are analyzed. The IEEE typical system is used to compare and verify the experimental examples. Theoretical analysis and experimental results show that the recursive algorithm has high identification accuracy, stable identification results and fast identification speed. It is suitable for the identification of objects with large numbers of nodes and complex structures, which is conducive to real-time monitoring and fast perception of the inertia constant of the new energy power system.