Distortion Factor Research Articles

Capacity and Error Probability Analysis of Neuro-Spike Communication Exploiting Temporal Modulation

In this paper, we consider a neuro-spike communication system between two neurons where nano-machines are used to enhance ability of neurons. Nano-machines can be employed for stimulation tasks when neurons have lost their ability to communicate. In the assumed system, information is conveyed via the time intervals between the input spikes train. For efficiency evaluation of temporal coding, we model the neuro-spike communication system by an additive Gamma noise channel. We present this model by considering different time distortion factors in the neuro-spike system. Then, we derive upper and lower bounds on the channel capacity. We analyze the channel capacity bounds as functions of the time intervals between the input spikes and the firing threshold of the target neuron. Moreover, we propose maximum likelihood and maximum a posteriori receivers and derive the resulting bit error probability when the system uses binary modulation. In addition, we obtain an upper bound for this error probability. Then, we extend this upper bound to the symbol error probability of the $T$ -ary modulations. Simulation results show that this upper bound is tight. The derived results show that temporal coding has a higher efficiency than spike rate coding in terms of achievable data rate.

Feed‐forward control scheme to improve light‐load power factor for single‐stage flyback PFC converters

In this Letter, the author proposes a new feed-forward controller for single-stage flyback power factor correction (PFC) converters. By compensating the phase-lead effect caused by input capacitor current, the proposed feed-forward control duty improves the displacement factor as well as the distortion factor, and so the flyback PFC converter has high power quality. By means of the synchronous rectification circuit, the flyback PFC converter can operate in reverse when the negative current is required. To confirm the theoretical analysis and validity of the proposed control scheme, the author demonstrated the proposed control algorithm with 80 W flyback PFC converter prototype.

Interweaving Network: A Novel Monochromatic Image Synthesis Method for a Photon-Counting Detector CT System

With the growing technology of photon-counting detectors (PCD), spectral CT is an important topic for its potential in material differentiation. However, direct reconstruction of the detected spectrum without any compensation will lead to inaccurate results due to some non-ideal factors such as cross talk and pulse pile-up in the detectors. Conventional methods try to model these factors using calibrations and make compensations accordingly, but the results depend on the model calibration accuracy. In this paper, we proposed an Interweaving Network (WeaveNet), a novel deep learning-based monochromatic image synthesis method working in sinogram domain. Unlike previous deep learning-based methods, the WeaveNet architecture was designed based on the factor of spectrum distortion and it can solve this problem better in an intuitive way. The method was tested on a cone-beam CT (CBCT) system equipped with a PCD. After FDK reconstruction of the synthesized monochromatic projection, we evaluated the accuracy of linear attenuation coefficient, decomposition coefficient and separation angle of different materials to examine the performance of our method. This method gives more accurate results with less noise than previous methods, which demonstrates the advantages of this monochromatic image synthesis method.

Using the system-functional approach to assess the development of housing construction

The article substantiates the methodology of the system-functional approach to organizing financing and ensuring the functioning of the complex, the use of which allows you to quickly identify and eliminate the factors of non-market distortions in the development of the housing complex and increase the efficiency of its functioning. The possibilities of practical application of the methodology at different levels of the organization of the economy are revealed The most powerful distorting effects arising from the redistribution of incomes created by market participants that do not correspond to their role in economic processes, due to a violation of the proportions of reproduction, the formation of incentives to obtain nonmarket income are highlighted.

A novel hybrid space vector-based modulation technique for power quality improvement in a wind energy conversion system

The paper develops a novel hybrid space vector pulse width modulation (HSVPWM) for improving the quality of power transfer from a permanent magnet synchronous generator (PMSG) based wind energy conversion system (WECS) to a three phase induction motor load. It includes a Vienna rectifier (VR) based ac-dc converter in the front end and a voltage source inverter (VSI) for providing the variable frequency, variable voltage requirements of the induction motor load. The Vienna rectifier attempts to offer almost a unity power factor and early sinusoidal input as the input to the VSI as part of resurrecting the shape of the supply side waveform to the motor. The formulation involves a three-phase three-level HSVPWM along with a novel hysteresis current control technique for generating the firing pulses to the power switches in the VSI. The simulation results reveal a higher fundamental component a lower total harmonic distortion (THD) and harmonic spread factor (HSF) for the inverter output voltage over the similar other pulse width modulation (PWM) schemes and allow it claim a space for its use in real world utilities.

Simulation of a model DC-DC converter with cascaded via improvement PFC with boost converter and THD using multiple loads

In this paper proposed a converter which improves the total harmonic distortion (THD) and power factor correction (PFC). In proposed DC side boost converter accompany through the forward converter....

New device for dental radiographic standardization

Context: The device for dental radiographic standardization (DDRS) was developed to minimize the distortions in conventional periapical radiographs or digital subtraction, improving the effectiveness of the technique. Objectives: The objective of this study is to present the DDRS and prove its effectiveness through comparative test, performed with the techniques of Bissetrix and Parallelism. Configurations and Design: The DDRS adapts to the universal radiographic positioner, is economical, and easy to operate. It is recommended for the use in research, where standardization is a requirement. Subjects and Methods: DDRS is produced using the additive manufacturing method for prototyping, after creating a three-dimensional (3D) model using a specific program (Autodesk Inventor 2016, Autodesk, Inc, California, USA). The final prototype was converted to the STL format, which was later read by a 3D printer (3D Machine ONE, Sao Paulo, Brazil). To perform the tests, three radiographic techniques were compared, Bisecting angle technique, parallelism and DDRS fitted to the universal positioner, and two examiners performed the evaluation independently. Statistical Analysis Used: Differences between the techniques were compared by the analysis of variance, followed by Dunnett’s multiple comparisons. The variability of the measured values among the techniques was compared by the Levene’s test. The intraclass correlation coefficients were calculated to evaluate the reproducibility and interexaminer agreement for each technique and parameter. Results: DDRS eliminates the effect of distortion factors that normally affect conventional methods, allowing greater reliability in the interpretation of the image before, during, and after treatment. Conclusions: The DDRS should be used for clinical and routine research purposes, facilitating comparisons of the same image at different time intervals, with minimized errors of vertical and horizontal angulation. This allows greater reliability in the interpretation of the image in relation to the structures of interest.

Perspective Distortion Modeling for Image Measurements

A perspective distortion modelling for monocular view that is based on the fundamentals of perspective projection is presented in this work. Perspective projection is considered to be the most ideal and realistic model among others, which depicts image formation in monocular vision. There are many approaches trying to model and estimate the perspective effects in images. Some approaches try to learn and model the distortion parameters from a set of training data that work only for a predefined structure. None of the existing methods provide deep understanding of the nature of perspective problems. Perspective distortions, in fact, can be described by three different perspective effects. These effects are pose, distance and foreshortening. They are the cause of the aberrant appearance of object shapes in images. Understanding these phenomena have long been an interesting topic for artists, designers and scientists. In many cases, this problem has to be necessarily taken into consideration when dealing with image diagnostics, high and accurate image measurement, as well as accurate pose estimation from images. In this work, a perspective distortion model for every effect is developed while elaborating the nature of perspective effects. A distortion factor for every effect is derived, then followed by proposed methods, which allows extracting the true target pose and distance, and correcting image measurements.

Optimal Input and Output Power Quality Control of Single-Phase AC–DC–DC Converter With Significant DC-Link Voltage Ripple

A single-phase isolated ac-dc-dc converter with low total harmonic distortion and high power factor usually suffers from a significant ripple power at double line frequency. The inherent ripple power brings a significant low-frequency voltage ripple on the dc-link capacitor. To reduce the voltage ripple, bulky electrolytic capacitors and hardware low-pass filter are widely adopted. However, the converter becomes bulky because of large capacitor. In order to reduce the dc-link capacitance, optimal control strategies are proposed for ac-dc and dc-dc converter, respectively, in this article. First, the notch filter with current disturbance feedforward strategy (NF-CDFS) are proposed to minimize input harmonic current of ac-dc converter. Second, the feedback linearization with voltage disturbance feedforward strategy (FLVDFS) is designed to suppress the output voltage ripple of dc-dc converter based on generalized state space averaging model. With the proposed NF-CDFS plus FLVDFS control strategy, low input harmonic current and low output voltage ripple are achieved. In addition, more than about 85% of dc-link capacitance is reduced compared to conventional methods.

Robust and blind watermarking algorithm based on DCT and SVD in the contourlet domain

A blind watermarking algorithm in multiple transform domains is presented for copyright protection. This robust algorithm is designed by fusing contourlet transform (CT), discrete cosine transform (DCT) and singular value decomposition (SVD). The host image is first decomposed by one-level CT and its low frequency sub-band is partitioned into 8 × 8 non-overlapping blocks. Then, each block is transformed by DCT and several middle frequency DCT coefficients with good stability are selected to construct the carrier matrix. Finally, the watermark is embedded by modifying the largest singular values of two carrier matrices. Besides, the geometric distortion factor is estimated with the speed up robust features (SURF) algorithm. The proposed watermarking scheme is evaluated in terms of imperceptibility and robustness. Experimental results demonstrate that the proposed watermarking scheme preforms better in terms of invisibility and robustness than other related schemes.

Power Quality Survey of Voltage Stabilizers and Uninterruptible Power Supply With Nonlinear Loads

Amongst the power quality problems faced in Nigeria, interruption and voltage fluctuation seem to be foremost. Thus, household electrical and electronic appliances are most times under the threat of outages and low voltage supply which cause them to malfunction or in extreme cases, get damaged. To address these problems, the use of uninterruptible power supply (UPS) and automatic voltage regulator commonly refer to as “stabilizer” has become very popular. The objective of this work is to examine the quality of these devices when powering other nonlinear devices. The experimental study was carried out by using a power harmonic analyzer to display the output parameters and waveform from each device under test when powering nonlinear loads. Parameters measured for each device were voltage, current, frequency, peak-to-peak voltage, total harmonic distortion (THD) and crest factor. The results showed that for the measured parameters, while other parameters relatively remain within the standards, the THD took an exemption as it was relatively higher with a range of 9.9 to 19.9 % for various combination of loads. Though the outputs from the UPS were relatively higher than that of stabilizer (except for THD and crest factor where those of the stabilizer were higher), there was no significant difference between the parameter values measured. The implication of this was that increasing utilization of UPS and stabilizer will invariably continue to contribute more to the pollution of the existing weak network. Adequate measures were suggested to mitigate this. This research can be useful for the stakeholders in power industry for power quality improvement.

Analysis of 6-Pulse and 12-Pulse in Conversion of the 115VAC/400Hz to 270 VDC for Application on Fighter

The development of aircraft secondary power technology is moving from mechanical power, pneumatic power and hydraulic power to electric power. The trend toward electric power is known as More Electric Aircraft (MEA). Modern military aircraft are designed using 270VDC for electric power system. Today, some military aircraft still use 115VAC/400Hz for their electrical power system. If this type of aircraft need provides 270VDC electrical power, then they require Multi-Pulse Transformer Rectifier Unit (TRU). The development of this type TRU has not been aimed to comply with aircraft military standards. This research investigates the variation of the number of pulses (p) and firing angle (α) to the amplitude ripple voltage, output voltage, and distortion factor in order to comply with the MIL-STD-704F standards. The multi-pulse transformer rectifier unit being analyzed consists of 6-Pulse and 12-Pulse. The research shows that the amplitude ripple voltage and distortion factor of the 6-Pulse TRU do not comply MIL-STD-704F. The amplitude ripple voltage and distortion factor of 12-Pulse comply MIL-STD-704F with firing angle (α) ≤4°.Keywords: Transformer Rectifier Unit, thyristor, ripple voltage, distortion factor, firing angle

Application of Bis[2-(3,4-epoxycyclohexyl)ethyl] octamethyltetrasiloxane in the Preparation of a Photosensitive Resin for Stereolithography 3D Printing

Bis[2-(3,4-epoxycyclohexyl)ethyl]octamethyltetrasiloxane is also called diepoxycyclohexylethyl octamethyltetrasiloxane. In the present paper, diepoxycyclohexylethyl octamethyltetrasiloxane was synthesized, and the synthesized product was characterized by FTIR and 1HMR. The synthesized product was compounded with some acrylates and an expoxide as well as photoinitiators to obtain a 3D printing stereolithography resin (3DSLR111). The properties of 3DSLR111 and its UV-cured samples were investigated by some instruments and equipments. The experimental results show that the critical exposure (Ec) of 3DSLR111 is 10.1 mJ/cm2, its penetration depth (Dp) is 0.15 mm, and its viscosity at 30 °C is 319 mPa·s. Some samples were printed with 3DSLR111, and their linear shrinkage and warping factor were evaluated. The linear shrinkage and the curl distortion factor are less than 0.80% and 7.30%, respectively, which indicates that the sample printed with 3DSLR111 has high accuracy, and that the synthesized diepoxycyclohexylethyl octamethyltetrasiloxane can be well applied to the preparation of the photosensitive resin for stereolithography 3D printing.

Swift Heavy Ion Irradiated Low-Density Polyethylene: Structural and Optical Investigations

The structural and optical effects of copper (50 MeV) and carbon (70 MeV) ion irradiation of low density polyethylene (LDPE) are described. X-ray diffraction (XRD) and differential scanning calorimetric (DSC) techniques were used to explore the structural behavior, while Fourier transform infrared (FTIR) and UV-visible spectroscopies were used to collect the optical data. Structural parameters, such as interplanar separation, distortion factor, crystallite size and degree of crystallinity, were measured to understand the change in the structural behavior of LDPE caused by the swift heavy ion irradiation. In the irradiated polymeric samples, the formation and growth of new carbon enriched species were revealed by the FTIR and UV-visible analysis, which led to the decrease of their optical bandgap energy with the increase of ion fluence.

Analysis of the influencing factors of electric field distortion caused by the lightning rod

Analysis of the influencing factors of electric field distortion caused by the lightning rod

The frequency converter with autonomous inverter output power flow research for various working modes

Energy characteristics of electric drives with frequency converters are generally determines with unit working mode and effectiveness of autonomous inverter (AI) operating, which set the voltage level for the actuating machines windings. Also, the structure of output power flow, consumed by actuating engine has been determined in dependence with AI mode. These facts explain the actuality of researches in the field of semiconductor converter working mode, it output power and control methods. The two methods of autonomous inverter operating have been investigated: pulse-width modulation and phase modulation. The paper shows that during pulse-modulation mode voltage distortion factor decreases, but the current distortion factor increases. Output phase current and voltage hodographs show that resultant vectors of this coordinates during PWM mode moves with higher smoothness, but in phase modulation mode it moves in steps. Power distortion for PWM mode is higher, active power share in the total power structure decrease. It leads to higher energy consumption during AI operating with an equal load. For the power consumption decreasing and higher energy efficiency, it recommended using energy saving control algorithms, providing smooth resultant output voltage hodograph shifting and higher voltage distortion factor value.

Power Quality Investigation of Single Phase Grid-connected Inverter of Photovoltaic System

There is a growing demand for renewable energy resources in countries all around the world. Among renewable energy resources, solar energy is a prominent and promising alternative to meet future electricity needs. Recently, the renewable energy regulations in Jordan have been modified to allow customers to install their own photovoltaic (PV) generators to cover their full energy consumption. This study investigated the power quality profile of single-phase grid-connected PV system in a typical Jordanian low voltage electrical system. The following electrical parameters were monitored: voltage, current, harmonics contents, total harmonics distortion (THD), active power, reactive power, and power factor. Detailed investigations and analyses were made.

Intrinsic Magnetic and Ferroelectric Behaviour of Non-magnetic Al3+ Ion Substituted Dysprosium Iron Garnet Compounds

Synthetic garnets are a group of oxide materials that play a vital role in the development of solid state lasers, magnetic and optic-electronic devices. The analysis on the solubility of rare-earth elements in the well-crystallized system has led to the discovery of peculiar oxide materials with multifunctional properties. By following the above importance, Aluminium ion (Al3+) substituted Dysprosium Iron Garnet compounds with the chemical formula of Dy3Fe5−xAlxO12 (x = 0–0.5) have been synthesized by the solid state reaction method and the effect of substitution of non-magnetic ions into the magnetic sub-lattices have been analyzed. The Rietveld refinement of powder x-ray diffraction patterns confirms that the pure Dy3Fe5O12 compound crystallizes with cubic (Space group: Ia3d) superstructure whereas all the Al3+ substituted samples exhibit the coexistence of cubic (Ia3d) and trigonal Fe2O3 (R3c) phases. The energy gap values of the prepared compounds is found to be around 1.6 eV which reveals the semiconducting nature and the decreasing trend of band gap values may be due to the growth factor of crystallites, structural disorder and distortion introduced into the crystal lattice. From the Micro-Raman analysis, it is found that the substituted Al3+ ions starts filling into both tetrahedral and octahedral positions and the assignments of vibrational modes observed from Raman spectra confirm the incorporation of Al3+ ions into the Dy3Fe5O12 garnet structure. From the magnetization analysis, it is found that the response of super-exchange interaction between Fe3+ ions in the a and d sites of Dy3Fe5O12 compound leads to net magnetic moment and the substitution of Al3+ ions preferably replaces Fe3+ ions in d sites and suggests the decrease in net magnetization values. From the photoluminescence studies, it is noticed that the luminescence behavior of Al3+ ions substituted Dy3Fe5−xAlxO12 compounds are due to the superposition of a broad emission band and reveals the variation in concentration of Al3+ ions in the prepared compounds. An interesting point to note is that, a well saturated “soft” ferroelectric hysteresis loop is obtained in both pure and Al3+ substituted Dy3Fe5−xAlxO12 compounds, and the observed electric hysteresis loops are found to be influenced by the factors such as capacitance nature, resistivity effects and leakage current of the compounds. Hence, the study on effect of trivalent non-magnetic ion substitution in a hard magnetic Dy3Fe5O12 system leads to interesting intrinsic magnetic and ferroelectric properties and found suitability for the fabrication of energy storage and optoelectronic devices.

Auxiliary Information Based Mixed EWMA–CUSUM Mean Control Chart with Measurement Error

Measurement error is a usually met distortion factor in real-world applications that influences the outcome of a process. The performance of the control charts can be affected in the presence of measurement error which also leads to erroneous conclusions regarding the average run length. In this paper, we proposed regression estimator-based mixed exponentially weighted moving average-cumulative sum (MxEMCUS) control chart to monitor the process mean and investigate the effect of measurement error on shift detection ability of the proposed control chart. The performance of MxEMCUS control chart is evaluated in the cases of mean shift with and without measurement error. The linear covariate model is used to evaluate the control chart in the presence of measurement error. The case of multiple measurements and linear increasing variance is also investigated in the presence of measurement error. The average run length and standard deviation of run length are used as the performance measuring tool. Based on simulation results, it is concluded that in the presence of measurement error, proposed chart has better performance as compared to other existing charts. An example with real data set is given to demonstrate the implementation of MxEMCUS control chart.

Low Total Harmonic Distortion and High Power Factor in Parallel Active Power Filter

In a modern power system with the increasing use of power electronics components, nonlinear loads connected to the grid cause power quality problems. To overcome the power quality problems, the parallel active power filter PAPF is used in power systems. In this study, the synchronous reference frame based a new control algorithm is proposed for the three-phase PAPF system. In the proposed control algorithm, synchronous reference frame SRF method and moving average filter MAF filter and space vector pulse width modulation SV-PWM technique are used to obtain low total harmonic distortion and high power factor. SRF method and MAF filter are used to calculate the reference current signal. SV-PWM technique is used to obtain the switching signals of active switches used in power filters. In the proposed algorithm, the number of measurements is reduced and performance is increased by using source ab currents and ab voltages without filter abc currents and abc voltages and load abc currents. Simulation studies of the proposed control algorithm have been tested using PSIM software. According to the simulation results, it is seen that the proposed control algorithm is more successful in eliminating the harmonics in the source current and compensating the reactive power than the other control method used in the literature. Keywords: Parallel active power filter, Space vector PWM, MAF filter, Power factor, Total harmonic distortion. DOI: 10.7176/JSTR/5-10-07