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Copyright of Irrigation & Drainage is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a reconfigurable image confusion scheme, which uses Linear Congruential Generators (LCGs)-based Pseudorandom Bits Generator (PRBG). The PRBG is based on the variable input-coupled LCG with a reconfigurable clock divider. The proposed algorithm encrypts the input image up to four times successively using different random sequences in every attempt. This new scheme aims to efficiently extract statistically strong pseudorandom sequences from a proposed PRBG with a large keyspace and simultaneously increase the security level of the encrypted image. This PRBG was initially designed on Virtex-5 (XC5VLX110T), Virtex-7 (XC7VX330T) and Artix-7 (XC7A100T) Field Programmable Gate Arrays (FPGAs). The statistical properties of the proposed PRBG for four different configurations are verified by the National Institute of Standards and Technology (NIST) tests. Thereafter, a reconfigurable encryption/decryption algorithm that uses the proposed PRBG is developed for secure image encryption. The encryption process was accomplished using the MATLAB tool after obtaining the PRBG keys from the FPGA. To show the quality and strength of the encryption process, security analysis [correlations and Number of Pixels Change Rate (NPCR)] is performed. Security analysis results are compared with the conventional encryption algorithm to show that the developed reconfigurable encryption scheme provides better results in security tests. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The valved linear compressor (VLC) is an essential part of the Joule-Thompson (J-T) throttling cryocooler in the liquid helium temperature region. The pressure pulsation may cause the fluctuation of the temperature and cooling capacity of the cryocooler, thus affecting its temperature stability. To measure the pressure pulsation of the VLC's pipe system, the mathematical model of pressure pulsation in the buffer tank of the VLC was established with the transfer matrix method based on the plane wave theory. The quantitative representation of the pulsating mass flow of the VLC was obtained with the linear damping based on the plane wave theory. Then, a test bench was set up to measure the pressure pulsation. The influence of the VLC's operating frequency and the suction and discharge buffer tank volume on the pressure pulsation was discussed. Results show that the pressure pulsation of the pipe system is related to the VLC's operating frequency. The pressure pulsation of the pipe system increases with the increase of the VLC's operating frequency. Both the inlet and outlet buffer tanks can effectively inhibit the pressure pulsation, but their capability is independent of each other. The pressure pulsation inhibition effect is better with the increase of the buffer tank volume. With the increase of the buffer tank volume, the pressure inhomogeneity at the inlet of the inlet buffer tank decreases to 164 over 423, but the pressure inhomogeneity at the outlet of the outlet buffer tank decreases to 8 over 23.

This manuscript includes the design and evaluation of the new four 16×16 S-boxes for subbyte operation in image encryption applications and estimates their strength using the following parameters: Dynamic Distance, BIC non-linearity, Bijective, Non-linearity, Strict Avalanche Criterion (SAC), and Balanced criterion. The S-box matrix is designed by a new reconfigurable 3D-Chaotic PRNG. This PRNG is designed using four different 3D chaotic systems i.e. Lorenz, Chen, Lu, and Pehlivan's chaotic systems. This reconfigurable architecture of PRNG exploits the ODEs of these four attractors that fit all four chaotic systems in a single circuit. The first part of this manuscript is focused to develop hardware-efficient VLSI architecture. To demonstrate the hardware performance, the PRNG circuit is implemented in Virtex-5 (XC5VLX50T) FPGA. A performance comparison of proposed and existing PRNGs (in terms of timing performance, area constraint, power dissipation and statistical testing) has been presented in this work. The PRNG generates the 24-bit random number at 96.438-MHz. The area of FPGA is occupied by only 16.66 %, 1.08%, 0.33%, and 1.15% of the available DSP blocks, slice LUTs, slice registers and slices respectively. The designed S-boxes using reconfigurable PRNG fulfill the following criteria: Dynamic Distance, BIC non-linearity, Bijective, Non-linearity, Strict Avalanche Criterion (SAC), and Balanced criterion.

This manuscript includes the design and evaluation of the new four 16×16 S-boxes for subbyte operation in image encryption applications and estimates their strength using the following parameters: Dynamic Distance, BIC non-linearity, Bijective, Non-linearity, Strict Avalanche Criterion (SAC), and Balanced criterion. The S-box matrix is designed by a new reconfigurable 3D-Chaotic PRNG. This PRNG is designed using four different 3D chaotic systems i.e. Lorenz, Chen, Lu, and Pehlivan's chaotic systems. This reconfigurable architecture of PRNG exploits the ODEs of these four attractors that fit all four chaotic systems in a single circuit. The first part of this manuscript is focused to develop hardware-efficient VLSI architecture. To demonstrate the hardware performance, the PRNG circuit is implemented in Virtex-5 (XC5VLX50T) FPGA. A performance comparison of proposed and existing PRNGs (in terms of timing performance, area constraint, power dissipation and statistical testing) has been presented in this work. The PRNG generates the 24-bit random number at 96.438-MHz. The area of FPGA is occupied by only 16.66 %, 1.08%, 0.33 %, and 1.15% of the available DSP blocks, slice LUTs, slice registers and slices respectively. The designed S-boxes using reconfigurable PRNG fulfill the following criteria: Dynamic Distance, BIC non-linearity, Bijective, Non-linearity, Strict Avalanche Criterion (SAC), and Balanced criterion. [ABSTRACT FROM AUTHOR]

Due to operational limitations in the industrial field, the operating variables of fluid catalytic cracking units (FCCU) are of multiple operating frequencies, which are CO combustion promoter amount, recycle slurry flow rate, combustion air flow rate, heat escape, and reaction temperature, from low frequency to high frequency. There are usually two schemes for operation optimization of FCCU. The former is called single-rate, single-window optimization, whose operating variables are optimized only once in the whole operation cycle, which is easy to achieve, but the optimization effect is poor. The latter is called single-rate multi-window optimization, whose operating variables are optimized repeatedly and whose operation cycle is discretized into multiple optimization periods with the same frequency, which costs a heavy calculation burden and cannot adapt to the optimization variables with multiple operating frequencies. So, a multi-rate, variable-window online dynamic optimization method is proposed. In an operation cycle, the high-frequency operating variable is optimized in a short optimization period, and the low-frequency operating variable is optimized in a long optimization period; each optimization period has integer multiples to the minimum optimization period. Each optimized result for each optimization period is put into use online immediately. The optimization model involves the time domain differential equations, integral cost objective function, and measured disturbances. The experimental results show that compared with the single-rate, single-window optimization method and single-rate multi-window optimization method, the optimization effect of multi-rate, variable-window online dynamic optimization is better than single-rate, single-window optimization but worse than single-rate multi-window optimization. However, the optimization results are consistent with the operation frequency of each optimization variable, which can be implemented in complex chemical processes and increase certain economic benefits. [ABSTRACT FROM AUTHOR]

Scientists have been searching for new microwave dielectric materials due to the need for miniaturization and weight reduction of wireless patch antenna. The sol–gel method was used to prepare the TiχZn(1-χ)Al2O4 (x = 0.25) microwave dielectric ceramic nanoparticles and various measurements were carried out. The distinctive peaks of titanium and zinc aluminate with the typical face-centered cubic structure was noticed in the X-ray diffraction (XRD) patterns. Fourier transform infrared spectroscopy (FTIR) was used to confirm the functional groups, field-emission scanning electron microscopy (FESEM) was used to analyze the crystalline structure and the elemental composition was confirmed using energy dispersive spectroscopy (EDS). The substitution of Zn2+ for Ti2+ in ZnAl2O4 nanoparticles increased crystallite size, affecting dielectric permittivity. The dielectric permittivity (εr) of TiχZn(1-χ)Al2O4 nanoparticles was calculated using a 100 KHz to 1 MHz LCR spectrometer. It can be demonstrated that the Ti0.25Zn0.75Al2O4 sample has εr 22.78–23.45, making it a viable material for millimeter-wave applications. Additionally, a prototype patch antenna with dimensions 2.5 cm × 1.5 cm was fabricated using these dielectric ceramic nanoparticles and tested using a network analyzer, which exhibited a return loss of −12.82 dB at an operating frequency of 2.12 GHz.

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new method for the generation of pseudo-random bits, based on a coupled-linear congruential generator (CLCG) and two multistage variable seeds linear feedback shift registers (LFSRs) is presented. The proposed algorithm dynamically changes the value of the seeds of each linear congruential generator (LCG) by utilizing the multistage variable seeds LFSR. The proposed approach exhibits several advantages over the pseudo-random bit generator (PRBG) methods presented in the literature. It provides low hardware complexity and high-security strength while maintaining the minimum critical path delay. Moreover, this design generates the maximum length of pseudo-random bit sequence with uniform clock latency. Furthermore, to improve the critical path delay, one more architecture of PRBG is proposed in this work. It is based on the combination of coupled modified-LCG with two variable seeds multistage LFSRs. The modified LCG block is designed by the two-operand modulo adder and XOR gate, rather than the three-operands modulo adder and shifting operation, while it maintains the same security strength. The clock gating network (CGN) is also used in this work to minimize the dynamic power dissipation of the overall PRBG architecture. The proposed architectures are implemented using Verilog HDL and further prototyped on commercially available field-programmable gate array (FPGA) devices Virtex-5 and Virtex-7. The realization of the proposed architecture in this FPGA device accomplishes an improved speed of PRBG, which consumes low power with high randomness compared to existing techniques. The generated binary sequence from the proposed algorithms has been verified for randomness tests using NIST statistical test suites. [ABSTRACT FROM AUTHOR]

This paper proposes a parameter identification method for a PEM electrolyzer electrical equivalent circuit for pulse electrolysis. Since general water electrolysis mainly uses DC currents, identifying equivalent circuit parameters using electrical characteristics mostly ignores the operation frequency and unnecessarily adheres to the secondary RC model. However, looking at the Nyquist plot of the PEM electrolyzer, it can be confirmed that identifying the operational frequency is necessary, and the secondary RC model correction is essential. Therefore, the proposed method confirms the necessity of reconstructing an electrical equivalent circuit with a primary RC model by analyzing the transient cell voltage using step current inputs and calculating an appropriate operating frequency by identifying the parameters of the reconstructed equivalent circuit. To verify the proposed parameter identification method, a simulation was constructed from the raw test data of a 400 W commercial PEM electrolyzer. In addition, the hydrogen production amount was compared to DC using a pulse electrolysis experiment at the operating frequency obtained by the proposed method. [ABSTRACT FROM AUTHOR]

Recent studies have shown that ablation techniques have the potential to eradicate adrenal adenomas while preserving the functionalities of the adrenal gland and the surrounding anatomical structures. This study explores a new microwave ablation (MWA) approach operating at 5.8 GHz and using anatomical and dielectric characteristics of the target tissue to create directional heating patterns. Numerical simulations are executed in planar and 3D adrenal models, considering two energy doses. The numerical study is refined accounting for the vaporization of the tissue water content. Ex vivo experimental evaluations on porcine adrenal models complete the study. The numerical and experimental results show that spherical ablation zones are able to cover the target for both energy doses considered. Nonetheless, most of the non-targeted tissues can be preserved from excessive heating when low energy level is used. Numerical models accounting for water vaporization are capable to foresee the experimental temperature values. This study shows that the proposed MWA directional approach operating at 5.8 GHz can be considered for creating effective and selective ablation zones. [ABSTRACT FROM AUTHOR]

The risk of liquefaction phenomena increases during dynamic loading and can cause the shear failure of soil under foundations. Model tests for a small-scale model under vertical vibration loads are presented. The operating frequency was changed from 1000, 2500 to 3500 revolutions per minute and the amplitude of loading with time was applied as a sine wave. Several parameters were considered, such as the force-time history of the machine foundation, the final settlement of the foundation, the vertical stress inside the soil media, the excess pore water pressure and observed liquefaction phenomena. These observations were compared to the effect of the sub-base layer thickness under the footing and its ability to reduce the liquefaction phenomena. The results showed that the shape of the load–time history coincides with a sine wave and the increase in the operating frequency led to an increase in the measured vibration load. The settlement was observed to increase with increases in the operating frequency. The settlement depended on the state of the soil and the operating frequency applied. Increases in operating frequency of about 3 times led to an increase in the time interval of excess pore pressure and reached a maximum value. The phenomenon of liquefaction appeared clearly when sandy soil was in a loose state. When the soil changes to a medium state, the phenomena of liquefaction respond to the operating frequency more than the operating frequency in a loose state. No liquefaction occurs in a dense state. The use of a subbase layer more than 1.5 times the depth of the footing led to eliminating the liquefaction phenomena. [ABSTRACT FROM AUTHOR]

• With increasing the Fe 4 N content in the Fe-Fe 4 N particles, the operating frequency of the Fe-Fe 4 N particles SMCs was increased from 17.8 MHz to 132.6 MHz. • The loss analysis indicates that with increasing Fe 4 N content in Fe-Fe 4 N particles, the eddy current loss decreased from 920.8 kW/m3 to 201.4 kW/m3 at 3 MHz and 10 mT, the decline was approximately 78.1 %. High frequency magnetic properties of nitrided carbonyl iron powder soft magnetic composites (SMCs) were investigated. Fe-Fe 4 N particles with different Fe 4 N contents have been prepared by nitriding carbonyl iron powder at different treatment temperature and time. With increasing Fe 4 N content in Fe-Fe 4 N particles, the operating frequency of Fe-Fe 4 N particles SMCs increased from 17.8 MHz to 132.6 MHz, while the core loss decreased from 1481.3 kW/m3 to 1070.8 kW/m3 at 3 MHz and 10 mT. The loss analysis indicates that with increasing Fe 4 N content in Fe-Fe 4 N particles, the eddy current loss decreased from 920.8 kW/m3 to 201.4 kW/m3, the decline was approximately 78.1 %. It can be seen that the enhancement of the internal resistivity of the particles by nitriding carbonyl iron powder suppresses the loss of Fe-Fe 4 N particles SMCs, which is an effective way to improve their operating frequency. [ABSTRACT FROM AUTHOR]

Operating frequencies and isolation are two critical parameters for 5G smartphone antennas. However, most of the existing decoupling methods will cause the unexpected variations on the performance of antenna element, such that the designers have to spend a lot of time to adjust the configuration of antenna element again and again for the purpose of maintaining the desired performance. To address this issue, a decoupling structure, which introduces another path for canceling the coupling, is proposed in this work. Such method is helpful in achieving the high isolation between two coupled antenna elements without sacrificing the radiating‐mode performance and geometrical configuration of each individual antenna element. Under this method, an open‐slot antenna pair operating at the sub‐6 GHz band of 3.3–3.6 GHz is designed and an isolation higher than 11 dB is obtained. This decoupling method is capable of not only maintaining the original self‐performance of each antenna element but also attaining good isolation between two elements. Owing to this attractive feature, the proposed method is promising for supporting the design of antenna element and decoupling structure in two separate steps, which might save a lot of time in the future design of a large array or massive MIMO. [ABSTRACT FROM AUTHOR]

Reciprocating inkjet system (RIS) is an additive manufacturing technology in which drops are formed on a substrate by extruding liquid ink from ink chamber via the reciprocating movement of a micro needle. Depending on the diameter of the micro needle, RIS is capable of a small amount drop (approx. 1 pl) with a wide range of viscosity (1~300,000mPa.s) levels, unlike a piezoelectric inkjet printing which can perform only 1-15mPa.s. Also, RIS is capable of printing inks with various drop sizes (10µm to 1000µm). This wide range of printable ink viscosity is attributed to both the mechanical extrusion mechanism adopted in the method, and the size controllability associated with the micro-needle diameter. Furthermore, the printing frequency of RIS is typically limited to 1-20 Hz which is considerably lower than that of conventional inkjet printing, (1-10kHz) because the micro needle must move in a reciprocating manner through mechanical movement. Although the slow frequency is at times problematic for some applications, the controllability of the high-resolution drop sizes is beneficial in applications such as the repair of open circuits, solder paste dropping for interconnections and all kinds of substrates. This paper, therefore, focuses on the development of RIS wherein printing process parameters (needle diameter, needle moving velocity, distance from substrate, and reciprocating frequency of inkjet head) are optimized. Moreover, the RIS is utilized to print fine conductive patterns on a flexible polyethylene terephthalate (PET) substrate for the fabrication of printed sensor which are analyzed by optical characterization. The results are then documented and discussed along with the conclusions drawn. [ABSTRACT FROM AUTHOR]

The opposed single-cylinder free piston generator（OSFPG）has the characteristics of compact structure, variable compression ratio and low emission characteristics of common free piston generator, etc. More, it also has unique features such as high unit power, low vibration noise, and good motion stability, etc. So, in this research, a physical prototype platform based on OSFPG is built. For the key factors, both experiment and simulation have been combined to investigate the changes in OSFPG's work performance under different operating frequencies. It was found that operating frequency affected OSFPG's working characteristics through the entire combustion period. More, the combustion period of each combustion stage increased with the increase of the operating frequency, and the increase amplitude was gradually reduced with the advancing of the ignition advance angle, but the operating frequency affected the after burning period most. When the operating frequency changed from 15 Hz to 35 Hz, the after burning period was extended by at least 100 %. The important thing was that the indicated thermal efficiency of the OSFPG increased first and then decreased with the increase of operating frequency. When the operating frequency was 25 Hz, the OSFPG's indicated thermal efficiency could reach 40.4 %. • For the first time, the effect mechanism of the changing frequency on the operating characteristics for the free piston generator was explained. • Comprehensive analysis of the influence of operating frequency on the combustion characteristics for opposed single-cylinder free piston generator under direct injection. • The optimal operating frequency that can promote efficient combustion for opposed single-cylinder free piston generator under direct injection is proposed. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai University / Shanghai Daxue Xuebao is the property of Journal of Shanghai University (Natural Sciences) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper introduces an FPGA implementation of a pseudo-random number generator (PRNG) using Chen's chaotic system. This paper mainly focuses on the development of an efficient VLSI architecture of PRNG in terms of bit rate, area resources, latency, maximum length sequence, and randomness. First, we analyze the dynamic behavior of the chaotic trajectories of Chen's system and set the parameter's value to maintain low hardware design complexity. A circuit realization of the proposed PRNG is presented using hardwired shifting, additions, subtractions, and multiplexing schemes. The benefit of this architecture, all the binary multiplications (except X i ⋅ Y i and X i ⋅ Z i) operations are performed using hardwired shifting. Moreover, the generated sequences pass all the 15 statistical tests of NIST, while it generates pseudo-random numbers at a uniform clock rate with minimum hardware complexity. The proposed architecture of PRNG is realized using Verilog HDL, prototyped on the Virtex-5 FPGA (XC5VLX50T) device, and its analysis has been done using the Matlab tool. Performance analysis confirms that the proposed Chen chaotic attractor-based PRNG scheme is simple, secure, and hardware efficient, with high potential to be adopted in cryptography applications. [ABSTRACT FROM AUTHOR]

In this manuscript, new quadrant-based search algorithm with zero motion prejudgment is proposed for motion estimation (ME) in HEVC (High Efficiency Video Coding) standard. The HEVC standard is used to obtain efficient output with low motion estimation time. The proposed quadrant-based search algorithm is a fast block matching algorithm that obtain better block matching amid the current block and reference block. The zero motion prejudgment (ZMP) method is used to find the block, whether it is motion or static and it is used for decreasing the computational complexity (CC) in the proposed quadrant-based search algorithm. The proposed quadrant-based search algorithm with ZMP technique for motion estimation in HEVC is implemented on the FPGA hardware platform. The entire architecture is executed in Verilog HDL with Virtex-5 technology and integrated with Xilinx ISE Design Suite 14.5. The results are integrated into the CIF (352 × 288 pixels) and HD (1280 × 720 pixels) video input sequence. The evaluation metrics like PSNR, Motion estimation time, sum of absolute difference (SAD) value are analyzed with existing method like hexagon, adaptive root pattern algorithm, and diamond search algorithm. Then the hardware parameters like power consumption and maximum operating frequency are measured. The hardware utilization is reduced and the power consumption of the proposed model is diminished to 0.143 W. The maximal operating frequency of the proposed model is 440.470 MHz. The experimental outcomes demonstrate that the proposed motion evaluation approach in HEVC is more effective than existing algorithms. [ABSTRACT FROM AUTHOR]

Piezoelectric dc–dc converters operate between the series and parallel frequencies of the piezoelectric resonator to achieve soft switching and energy-balance conditions. This letter presents an experimentally validated model to accurately predict the operating frequency, the switching angles, and the piezoelectric current for any six-phase piezoelectric dc–dc converter. This model reduces the transient simulation's calculation time to reach the steady state. It can be used to initially setup the switching angles in the experiment or to predict the high-frequency spectrum generated by the converter cycle. [ABSTRACT FROM AUTHOR]

This paper reports a study of the electromagnetic processes in self-generating resonant inverters, as well as the derivation of analytical dependences of their operating frequency on the parameters of the resonance circuit and positive feedback circuits, in order to expand the range of their output power and optimize their operation. The object of research is electromagnetic processes in resonant inverters, in which autogeneration of resonant current oscillations is carried out in the process of operation. The results of studying the electromagnetic processes in sequential self-generating resonant inverters based on the characteristics of the resonant circuit are presented. The operating modes of the inverters have been optimized by setting certain ratios between the operating and resonant frequencies at unstable circuit parameters. The ratio of operating and resonant frequencies is set through the use of phase-shifting filters in a positive feedback loop along the circuit current and correspond to the autogenerator mode. The conditions of self-generation in converters with a sequential resonant circuit have been determined. Mathematical expressions have been built for determining the coefficients of positive feedback on the current and voltage of the resonant circuit, which made it possible to derive target analytical dependences. Analytical dependences of the established operating frequency on the parameters of the circuit and phase-shifting filters have been established. Based on the obtained dependences, the parameters of the positive feedback circuits have been determined in order to ensure a wide range of output power of the converters. The resulting dependences make it possible to carry out theoretical calculations whose results repeat the results of model experiments. Phase characteristics of the resonance circuit and various phase-shifting filters, which can be part of a serial resonant converter, have been constructed. The results of the analysis reported here could be used in the design of resonant inverters with unstable circuit parameters, in particular in inductive chargers. [ABSTRACT FROM AUTHOR]

In this study, a neuro-fuzzy (NF) analysis method is suggested for the estimation of the operating frequency of triangular ring patch antennas (TRPAs) that operate at ultra high band applications. Although the analysis of regular-shaped patch antennas (PAs) such as rectangular, triangle, and circle is easy, analysis of irregularly shaped patch antennas is difficult and time consuming. Here, this great effort and time has been eliminated by using an artificial intelligence technique such as NF. To create a data set for NF, 100 TRPAs with different physical and electrical properties (L, l, h, and er) are simulated by using an electromagnetic simulator program. The currency and accuracy of the proposed approach is then confirmed on the measurement results of a prototype TRPA fabricated in this study. The results of NF model are compared with the simulation/measurement results and previously the method published in the literature. [ABSTRACT FROM AUTHOR]

This paper introduces the design of a hardware efficient reconfigurable pseudorandom number generator (PRNG) using two different feedback controllers based four-dimensional (4D) hyperchaotic systems i.e. Hyperchaotic-1 and -2 to provide confidentiality for digital images. The parameter's value of these two hyperchaotic systems is set to be a specific value to get the benefits i.e. all the multiplications (except a few multiplications) are performed using hardwired shifting operations rather than the binary multiplications, which doesn't utilize any hardware resource. The ordinary differential equations (ODEs) of these two systems have been exploited to build a generic architecture that fits in a single architecture. The proposed architecture provides an opportunity to switch between two different 4D hyperchaotic systems depending on the required behavior. To ensure the security strength, that can be also used in the encryption process in which encrypt the input data up to two times successively, each time using a different PRNG configuration. The proposed reconfigurable PRNG has been designed using Verilog HDL, synthesized on the Xilinx tool using the Virtex-5 (XC5VLX50T) and Zynq (XC7Z045) FPGA, its analysis has been done using Matlab tool. It has been found that the proposed architecture of PRNG has the best hardware performance and good statistical properties as it passes all fifteen NIST statistical benchmark tests while it can operate at 79.101-MHz or 1898.424-Mbps and utilize only 0.036 %, 0.23 %, and 1.77 % from the Zynq (XC7Z045) FPGA's slice registers, slice LUTs, and DSP blocks respectively. Utilizing these PRNGs, we design two 16 × 16 substitution boxes (S-boxes). The proposed S-boxes fulfill the following criteria: Bijective, Balanced, Non-linearity, Dynamic Distance, Strict Avalanche Criterion (SAC) and BIC non-linearity criterion. To demonstrate these PRNGs and S-boxes, a new three different scheme of image encryption algorithms have been developed: a) Encryption using S-box-1, b) Encryption using S-box-2 and, c) Two times encryption using S-box-1 and S-box-2. To demonstrate that the proposed cryptosystem is highly secure, we perform the security analysis (in terms of the correlation coefficient, key space, NPCR, UACI, information entropy and image encryption quantitatively in terms of (MSE, PSNR and SSIM)). • Earlier related works are proposed reconfiguration architecture of PRNG using up to 3D chaotic attractors. As we know that hyperchaotic systems provide more complex dynamic behavior as compared to the chaotic system, therefore nowadays it is highly preferred in cryptography for key generation. Till date, reconfigurable design using 4D hyperchaotic attractors is not proposed due to their hardware complexity. • Now in this research work, we develop hardware efficient reconfigurable PRNG using two different feedback controllers based 4D hyperchaotic systems to fulfill this research gap. • To demonstrate these PRNGs and S-boxes, a new three different scheme of image encryption algorithms have been developed. [ABSTRACT FROM AUTHOR]

This paper proposes a parameter identification method for a PEM electrolyzer electrical equivalent circuit for pulse electrolysis. Since general water electrolysis mainly uses DC currents, identifying equivalent circuit parameters using electrical characteristics mostly ignores the operation frequency and unnecessarily adheres to the secondary RC model. However, looking at the Nyquist plot of the PEM electrolyzer, it can be confirmed that identifying the operational frequency is necessary, and the secondary RC model correction is essential. Therefore, the proposed method confirms the necessity of reconstructing an electrical equivalent circuit with a primary RC model by analyzing the transient cell voltage using step current inputs and calculating an appropriate operating frequency by identifying the parameters of the reconstructed equivalent circuit. To verify the proposed parameter identification method, a simulation was constructed from the raw test data of a 400 W commercial PEM electrolyzer. In addition, the hydrogen production amount was compared to DC using a pulse electrolysis experiment at the operating frequency obtained by the proposed method.

Recent studies have shown that ablation techniques have the potential to eradicate adrenal adenomas while preserving the functionalities of the adrenal gland and the surrounding anatomical structures. This study explores a new microwave ablation (MWA) approach operating at 5.8 GHz and using anatomical and dielectric characteristics of the target tissue to create directional heating patterns. Numerical simulations are executed in planar and 3D adrenal models, considering two energy doses. The numerical study is refined accounting for the vaporization of the tissue water content. Ex vivo experimental evaluations on porcine adrenal models complete the study. The numerical and experimental results show that spherical ablation zones are able to cover the target for both energy doses considered. Nonetheless, most of the non-targeted tissues can be preserved from excessive heating when low energy level is used. Numerical models accounting for water vaporization are capable to foresee the experimental temperature values. This study shows that the proposed MWA directional approach operating at 5.8 GHz can be considered for creating effective and selective ablation zones.

Superconducting pulsed power supplies (SPPSs) have attracted more and more attention because of their advantages of high energy storage density, long energy storage time, low loss, and low power requirements for charging power sources. In order to improve energy efficiency and output continuous pulse currents, a 20-Hz repetitive SPPS based on high temperature superconducting pulsed power transformer (HTSPPT) and residual energy recovery method is proposed and researched in this article. The main principle is that the residual energy is recovered and used for the next cycle of the repetitive SPPS for improving energy efficiency, shortening the charging time, and increasing the operating frequency. The working principle and procedure of the repetitive SPPS are introduced and analyzed in detail, and simulations are carried out to study the characteristics of the repetitive SPPS. The effects of the initial capacitor voltage and the switching trigger time of each cycle on the output characteristics are analyzed. The simulation results show that the repetitive SPPS with personalized trigger time can output a stable repetitive pulse current, that is, the output characteristics are stable. [ABSTRACT FROM AUTHOR]

The operating frequency of the networked control system (NCS) determines both its control performance and heat flux density. Considering the significant effect of thermal stress on the reliability of electronics, a quantitative reliability analysis framework is proposed for NCSs with the consideration of its operating frequency. It includes 5 main steps: 1) Compute the power consumption of all its electronic components using circuit simulation; 2) obtain the thermal stress of these components by thermal simulation; 3) apply the thermal stress results to assess the reliability of components using the part stress analysis method; 4) calculate the reliability of the modules using reliability block diagrams; and 5) quantify the reliability of the NCS by combining the graph reduction method and other network reliability algorithms together. A double loop networked control system is used as an example to verify the effectiveness of our method. [ABSTRACT FROM AUTHOR]

In this work, the architecture of a dual-coupled linear congruential generator (dual-CLCG) for pseudo-random bit generation is proposed to improve the speed of the generator and minimize power dissipation with the optimum chip area. To improve its performance, a new pseudo-random bit generator (PRBG) employing two-operand modulo adder and without shifting operation-based dual-CLCG architecture is proposed. The novelty of the proposed dual-CLCG architecture is the designing of LCG based on two-operand modulo adder rather than a three-operand one and without using shifting operation as compared to the existing LCG architecture. The aim of the work is to generate pseudo-random bits at a uniform clock rate at the maximum clock frequency and achieve maximum length of the random bit sequence. The power dissipation with the optimum chip area of PRBG is also observed for the proposed architecture. The generated sequence passes all the 15 tests of the National Institute of Standards and Technology (NIST) standard. Verilog HDL code is used for the design of the proposed architecture. Its simulation is done on commercially available Spartan-3E FPGA (ISE Design Suite by Xilinx) as well as on 90-nm CMOS technology (Cadence tool). [ABSTRACT FROM AUTHOR]

The microwave sensor is a key element of the microwave method for the gas-solid two-phase flow parameter measurement. The geometric size of the microwave sensor plays an important role on the transmiting, propagating and receiving of microwave signals, and thus on the signal quality. In this paper, the circular waveguide microwave sensor is optimized to achieve a minimum input reflection coefficient of the microwave propagating within the probe. The optimization is carried out at three operating frequencies of 5.8 GHz, 10 GHz and 24 GHz, by using the orthogonal experimental optimization method. Based on the extensive simulation results, it is concluded that the optimal sensor size is inversely proportional to the operating frequency. Experimentally, the rationality of the probe structure optimization is verified by measuring the received signal strength. Experimental tests are also conducted to evaluate the performance of the optimized sensor. Results show that the optimized sensor gives a highly received signal at the corresponding operating frequency. The numerical and experimental results indicate that the orthogonal experiment method is feasible for optimizing the microwave sensor probe, which provides a basis for the performance improvement of microwave sensor to measure the gas-solid flow. [ABSTRACT FROM AUTHOR]

Accurate synthesis of antenna radiation behavior is a complementary step towards simulation in antenna systems design process. In this paper, a spherical harmonic decomposition (SHD) and coupled structure electromagnetic statistical model (CSESM) methods are hybridized and adapted for the first time, to actively synthesize radiation characteristics using antenna feed array. The problem of finding the feed array aperture size, capable of synthesizing a required field intensity distribution, within a specified region for a reflector system signaling a satellite is also addressed. Relationship that exist between the required number of elements in feed array, frequency of operation, volume of the synthesis region, and the required reflector size is theoretically benchmarked. EM radiation behavior via antenna feed array is optimally synthesized using the proposed SHD-CSESM-based method. With this approach, operation limits on the synthesis of the signal field within a test volume of a given radius is predicted. Efficiency and effectiveness of SHD-CSESM-based EM field synthesis scheme unveiled are investigated for structures in a region where feed antennas are positioned distance away (focal point) from reflector system operating at Ka band. Experimental measurement data of a circularly polarized Ka-band $2\times2$ -antenna feed array is compared with the proposed theoretical method, and results obtained demonstrate the validity of the proposed algorithm. Furthermore, for any wave number ${k}$ or frequency f, the field radiation behaviour within the sphere can be accurately synthesized using an ${N}$ order expansion and ${V} \ge (4{N}+1)/{N}$ array size. Results obtained show that the proposed synthesis method handles constrains related to both aperture domain and radiation domain. Hence, SHD-CSESM-based technique is a good candidate for EM field synthesis, with the notion of automating system design processes in the emerging and future EM field applications. [ABSTRACT FROM AUTHOR]

Air‐to‐ground ranging (AGR) is one of the important operation modes of an airborne monopulse radar system. Here, an approach for the detailed modelling and simulation of the AGR performance of such a radar system over complex terrain is proposed. Time‐domain monopulse signals reflected by the terrain's surface were modelled using the dynamics of the airborne platform, clutter properties, and RF specifications of the radar, which included the operating frequency, antenna beam patterns, and pulse repetition time. The AGR performance was then numerically analysed by employing the modelled monopulse return signals and a digital elevation model of the terrain's surface. Several crucial factors affecting the accuracy of line‐of‐sight estimation, including shadowing effects and roll stabilisation, were addressed using numerical simulations of various scenarios. [ABSTRACT FROM AUTHOR]

The liquid‐infiltrated photonic crystal fibre (LI‐PCF) is proposed for guiding terahertz radiation. Geometrical asymmetry is achieved by introducing a large ellipse in the core. By filling the ellipse with liquid cocaine, the optical properties of the photonic crystal fibre (PCF) are theoretically examined using finite element method‐based COMSOL multiphysics software. At an operating frequency of 1 THz, the proposed LI‐PCF demonstrates a sensitivity of 87.02% and confinement loss in the order of 10−4 cm−1. The PCF also demonstrates extremely low effective material loss <0.01 cm−1, a birefringence of 0.018, large effective mode area of 1.11 × 105 µm2, a high numerical aperture of 0.45 and near‐zero ultra‐flattened chromatic dispersion of 1.4351 ± 0.5883 ps/THz/cm. The design simplicity and high sensitivity, strong confinement factor, low material losses and high birefringence of the fibre suggest that the proposed fibre may be convenient for PCF‐based cocaine sensing, for application in the security and defence industries. [ABSTRACT FROM AUTHOR]

Communication at higher frequency bands has numerous benefits but susceptible to rain impairments. Rain-induced attenuation becomes more prominent as the carrier frequency and rain rate increase. Hence, precise knowledge of rain rate can help in predicting the level of rain-induced attenuation. The paper determines point cumulative rainfall rate at 0.1% of time exceedance and converts integration time from 5 min to 1 min. The specific and the total rain-induced attenuation were predicted at 0.1% of time exceedance from 12 GHz to 18 GHz for both horizontal and vertical polarizations. Lavergnat-Gole rain rate conversion model and ITU-R P.838-3 model were employed using four-year rainfall data obtained from Port Harcourt, Nigeria. The results revealed that the peak activities of rainfall rates were recorded at lower integration times, and the total rain-induced attenuation increases with increasing operating frequencies, which is greater for horizontally polarized waves compared to vertically polarized waves. [ABSTRACT FROM AUTHOR]

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