Parallel Type Research Articles

Transmission line bandpass filters with multiple attenuation poles and small number of resonators

This article considers an alternative way to generate attenuation poles (AP) in bandpass filter (BPF) with parallel type resonators and admittance inverters. It consists in using special transmission line resonators, in which one or two antiresonant frequencies ωp1, ωp2 are placed next to the main resonant frequency ω0. These frequencies ωp1, ωp2 are the poles of the input admittance Y(jω). Four new resonators are synthesized in the article. Two resonators generate one AP, and other two resonators generate two APs located near the passband of the BPFs. If we use mixed couplings between proposed adjacent resonators in BPF, then the total number of APs will become quite large. This is because each mixed coupling adds one AP. N-order BPF without cross coupling can has (3 N – 1) APs. The increased number of APs improves the BPF selectivity, including the one-sided one. With APs, the filter can provide increased attenuation in certain frequency bands and effectively suppress unwanted signals. A microstrip second order BPF with center frequency f0 = 1 GHz and bandwidth BW = 70 MHz, which has five APs, is designed. It is compared with third order BPFs with two APs.

Comparisons and optimization of two absorption chiller types by considering heat transfer area, exergy and economy as single-objective functions

Abstract Absorption cooling technology is an environmentally friendly method to generate continuous chilled water making use of multiple thermal sources, such as waste heat and renewable thermal energy. In this study, two absorption chillers (nominal capacity of 400 kW) with series and parallel connections are evaluated. To research the ideal configuration of chillers after thermodynamic analysis, the structures of the chillers are optimized using the particle swarm optimization algorithm by considering the heat transfer area (HTA), exergy efficiency and total annual cost as single-objective functions. The impact of temperature differences between external and internal flows, heat exchanger efficiencies and the solution allocation ratio is estimated. The optimized HTA, coefficient of performance, exergy efficiency and total annual cost are 149.0 m2, 1.56, 29.44% and $229 119 for the series-connected chiller, and 146.7 m2, 1.59, 31.45% and $234 562 for the parallel-connected type, respectively. Under the lowest HTA condition, compared with the reference simulation results, the energy and exergy performances are improved, while the annual total cost is higher. The annual total cost is highest when maximizing the exergy efficiency, which is attributed to the increase in the HTA. The operating cost accounts for 27.42% (series type) and 26.54% (parallel type) when the annual cost is the lowest.

A Tbit/s parallel real-time physical random number scheme based on chaos optical frequency comb of Si<sub>3</sub>N<sub>4</sub> micro-ring

<sec>Physical random numbers (PRNs) own various advantageous characteristics, including unpredictability, non-repeatability, higher security and reliability. Meanwhile, laser chaos has attracted great attention in the field of PRN. In terms of single channel PRN, laser chaos schemes can achieve a much higher bit-rate than traditional quantum PRN schemes. So far, various laser chaos PRN schemes have been discussed in order to enhance the performance of single channel laser chaos PRN. However, considering the limited bandwidth of laser chaos, especially the bandwidth of digital electronic circuit, the development potential of single channel PRN should be limited and may fall into the trap of high performance and expensive cost. Recently, the applications of multi-channel parallel PRN schemes have been developed. These parallel types may balance the high performance of PRN in a low cost. Recent progress indicates that chaotic micro-comb may have good potential. The micro-comb exhibits highly nonlinear and complex dynamic characteristics, and each comb tooth may show chaotic oscillation. The wavelength division multiplexing technology enables large-scale optical parallel output, providing the possiblity for large-scale parallel PRN generation. However, most of these PRN schemes are offline rather than true online and real-time random numbers. Thus, the development of real, online real-time parallel PRN solutions has great interest and research value in related fields.</sec><sec>Herein we experimentally demonstrat an ultra-high-speed parallel real-time physical random number generator, which is achieved though the combination of chaotic micro-comb of chip-scale Si<sub>3</sub>N<sub>4</sub> ultra-high Q micro-resonator and a high-speed field programmable gate array (FPGA). The results show that the Si<sub>3</sub>N<sub>4</sub> ultra-high Q micro-resonator generates a micro-comb with hundreds of channels, each channel can route into an optically chaotic state, and become an excellent physical entropy source. Using FPGA onboard multi-bit analog-to-digital converter, the filtered optical chaos signal from the micro-comb is discretely sampled and quantized, and resulting in an 8-bit binary bitstream. Taking real-time self-delayed exclusive or (XOR) processing of bitstream and preserving 4 least significant bits, the qualified physical random bitstream with real-time 5 Gbits/s rate is realized experimentally. Considering that there are 294 chaotic comb teeths, our approach anticipates a throughput of 1.74 Tbits/s of real-time physical random bits. Our results could offer a new integrated and ultra-high-speed option for real-time physical random number sources.</sec>

ФОЛЬКЛОРНЫЙ ПРИЕМ В ЛИТЕРАТУРЕ: ПСИХОЛОГИЧЕСКИЙ ПАРАЛЛЕЛИЗМ

Psychological parallelism (artistic means based on juxtaposition of nature and individual life) emerged in folklore and further showed its productivity in literary work. It demonstrates the continuity of a national cultural tradition and broader plot and figurative potential of literature, compared to folklore. Of all types of psychological parallelism, outlined by A. N. Veselovsky, one-member parallelism (employing environmental imagery) and two-member parallelism (equating natural images and subjective experience) are most frequently observed in 19th century Russian poetry. The major mode of forming one-member parallelism is a symbol. The structure and semantics of psychological parallelism are illustrated by A. P. Chekhov's stories. The analysis of the literary material has shown that two-member and antithetic parallelism were used. The landscape is not merely a composition but the meaningful element which is crucial to precisely convey the heroine's emotions and feelings. Natural phenomena are directly associated with every character. The means plays not only a decorative but functional role and reveals a strong link between the writer and the national tradition.

Parallel line type permeameter for thick magnetic material to reduce the error of demagnetizing field

Parallel line type permeameter for thick magnetic material to reduce the error of demagnetizing field

Thermodynamic and structural investigation of the interaction of quaternized 2,3-octakis-[(2-mercaptopyridine)phthalocyaninato] copper (II) sulfate (CuPc) with parallel and hybrid type G-quadruplex.

G-quadruplexes are important drug targets and get attention due to their existence in telomere, ribosomal DNA, promoter regions of some oncogenes, and the untranslated regions of mRNA. Due to the biological roles of G-quadruplexes, investigating of the G-quadruplex-small molecule interaction is essential. The primary motivation for these studies is the possibility of inhibiting cell functions associated with G-quadruplex sequences by binding with small molecules. Targeting the small molecules to desired tissue with the G-quadruplex vehicles is the second important goal of the G-quadruplex-small molecule interaction studies. In the present study, the new peripherally 2-mercaptopyridine octasubstituted copper(II) phthalocyanine and its quaternized derivative (CuPc) were synthesized and characterized by elemental analysis FT-IR, UV-Vis, and mass spectra. The excellent solubility of CuPc in water is essential for its transport in the organism. Because of this feature, its affinity toward G-quadruplex forming aptamers, AS1411, Tel21, and Tel45, was investigated. The UV-Vis spectrophotometric titration data confirmed the prevention of aggregation upon interaction with G-quadruplex, which is very important for biomedical applications. The CD spectroscopic analyses and binding stoichiometry confirmed the "end stacking" model for interaction of AS1411 with CuPc. The interaction of CuPc caused the equilibrium shift from hybrid conformation to antiparallel conformation for Tel21 and Tel45. The isothermal titration calorimeter (ITC) was used for the determination of thermodynamic parameters. The thermodynamic data of the interaction was fitted well with the one-site model. The negative values of Gibbs free energy change confirmed the spontaneous nature of the reactions. Besides, the negative values of enthalpy change and entropy change proved that the nature of processes was "enthalpy driven." The interaction stoichiometry was 2 for AS1411 and Tel21 and 1.5 for Tel45. The binding constants were 1.3(±0.3) × 105 , 3.2(±0.4) × 105 , and 1.1(±0.3) × 105 M-1 , which were at the level of ethidium bromide intercalation binding constant given in the literature. The DNA polymerase stop assay further supported the interaction of CuPc with G-quadruplex DNA. The experimental results confirm that the CuPc has a potential photosensitizer behaviour for photodynamic therapy.

Electrical impedance tomography: a review on hardware systems and circuits

Abstract Electrical impedance tomography (EIT) is a widely used functional imaging technology in the field of biomedical engineering with the characteristics of non-radiation, high temporal resolution, real-time, miniaturization, and low cost, but with relatively poor spatial resolution, which makes it become an effective complementary imaging alternative in conjunction with structural imaging technologies such as MRI and CT for bedside monitoring. The hardware systems and circuits (HSC) are the physical basis for EIT, and have major impacts on imaging speed, accuracy, cost and other key performance specifications. This review attempts to provide researchers with a relatively comprehensive picture of HSC for different EIT systems, which is organized as follows. Firstly, the general EIT hardware systems are classified as serial, fully parallel and semi-parallel types, respectively, according to their hardware architecture. Secondly, the main analogy front-end circuits of EIT hardware systems are summarized, in which the current drive circuits are divided into open loop, linear closed-loop and nonlinear closed-loop based on different feedback types. Thirdly, the common error sources and evaluation indicators on EIT measurements are summarized. Finally, the future development trends and research challenges of EIT are discussed. This review is expected to promote the development of EIT technology, especially on the design of HSC.

Neoliberalism, education financing and development in Africa: The politics, synergism and contradictions in the Ghanaian perspective

The paper examines the sustainability of the new education policy in the light of the drifted neoliberal policies around the world. The researchers adopted a mixed method (MM) approach with the parallel mixed designs type to inquiry. The sampling approach is purposive sampling technique. The sample targeted 10 heads of senior high school, 50 teachers and 100 students in 10 deprived senior high schools across northern Ghana. More specifically, the study covered four thematic areas. It emerged that the free pre-tertiary education policy was implemented contra mundum by government; even though, the policy in principle has support from all spectrum of life. There has been a spillover effect and other contraindications of the policy in terms of funding, materials, manpower and infrastructure. Government and stakeholders in education need to find indigenous or domestic sources of funding the policy, since its benefits in the long run will outweigh its pitfalls.

УНІВЕРСАЛЬНИЙ ТРИФАЗНИЙ ПАСИВНИЙ ФІЛЬТР ГАРМОНІК СТРУМУ МЕРЕЖІ

An analysis of well-known universal filters of current harmonics was carried out. A variant of the three-phase passive filter of network current harmonics is proposed, due to the change in its structure, the value of the voltage on the load is limited in operating modes close to idling. Mathematical modeling of such a system, which feeds a bridge rectifier with a capacitive filter and an active load with a power of 5 kW, was performed. The load characteristics and the depend-ence of the current harmonic coefficient on the change in the load power of the developed filter are given. Ref. 2, fig. 3. Keywords: current harmonic coefficient, THDI, passive filter, active filter of parallel type, hybrid filter, decentralized power supply system.

Cooling Strategy Optimization of Cylindrical Lithium-Ion Battery Pack via Multi-Counter Cooling Channels

This study focused on the design of a battery pack cooling channel based on a Tesla Model S electric car. This study aimed to achieve a balance between cooling efficiency and pressure drop while maintaining safe and optimal operating temperatures for the batteries. A cooling channel design similar to the basic type employed in the Tesla Model S using 448 cylindrical Li-ion batteries was considered. Consequently, important parameters, such as the maximum temperature and temperature difference in the battery cells in a module, as well as the pressure drop of the coolant, were analyzed. In addition, the characteristics of the temperature changes in each cooling channel shape were investigated. The temperature limit for the battery in a module and the temperature limit difference were set to 40 °C and 5 °C, respectively, to evaluate the performance of the cooling system. Further, the effects of discharge rates (3C and 5C), cooling channel shapes (counter flow and parallel types), and coolant inlet velocities (0.1, 0.2, 0.3, and 0.4 m/s) on battery thermal management were analyzed. The results revealed that the parallel type channel yielded a lower pressure drop than the basic type channel; however, it was not as effective in removing heat from the battery. In contrast, the counter flow type channel effectively removed heat from the batteries with a higher coolant pressure drop in the channel. Therefore, a multi-counter flow type cooling channel combining the advantages of both these channels was proposed to decrease the pressure drop while maintaining appropriate operating temperatures for the battery module. The proposed cooling channel exhibited an excellent cooling performance with lower power consumption and better heat transfer characteristics. However, relatively minimal differences were confirmed for the maximum temperature and temperature difference in the battery module compared with the counter flow type. Therefore, the proposed cooling channel type can be implemented to ensure the optimal temperature operation of the battery module and to decrease system power consumption.

Efisiensi Daya Sel Surya Menggunakan Konverter DC-DC Mensuplai Beban Listrik

The maximum solar cell power capacity without load parameter Pm(no-load) = 0.4 watts is used to supply an external electrical load with a resistor R in ohms. Irradiation of the solar cell surface area during the day in bright sunlight supplies an electrical load with a resistor R = 100 Ω which absorbs solar cell power with parameters Psel(R) = 0.09 watts. The power efficiency of a solar cell loaded with a resistor R is expressed as the parameter eff.sel(R) which is the result of a comparison between the power Psel(R) = 0.09 watts and the power Pm(no-load) resulting in a value of eff.sel(R) = 22.5% . Achieving solar cell to more effectively supply a resistor load of R = 100 Ω is efficiency done by adding a parallel FC-75 type dc-dc buck converter device to the solar cell output. Test results: The input power of the FC-75 dc-dc buck converter is Pi(conv.) = 0.178 watts. The resistor load R absorbs the output power Po[conv.(R)] = 0.078 watts. The power efficiency of solar cells using a dc-dc buck converter is expressed as the eff.sel(conv.) parameter. The results of the comparison between the power Po[conv.(R)] and the power Pi(conv.) reach 43.82%. The achieved power efficiency results for solar cells supplying resistor load R using a dc-dc buck converter are eff.sel(conv.) = 43.82%, which is greater than eff.sel(R) = 22.5%.

Pipelined Stochastic Gradient Descent with Taylor Expansion

Stochastic gradient descent (SGD) is an optimization method typically used in deep learning to train deep neural network (DNN) models. In recent studies for DNN training, pipeline parallelism, a type of model parallelism, is proposed to accelerate SGD training. However, since SGD is inherently sequential, naively implemented pipeline parallelism introduces the weight inconsistency and the delayed gradient problems, resulting in reduced training efficiency. In this study, we propose a novel method called TaylorPipe to alleviate these problems. The proposed method generates multiple model replicas to solve the weight inconsistency problem, and adopts a Taylor expansion-based gradient prediction algorithm to mitigate the delayed gradient problem. We verified the efficiency of the proposed method using the VGG-16 and the ResNet-34 on the CIFAR-10 and CIFAR-100 datasets. The experimental results show that not only the training time is reduced by up to 2.7 times but also the accuracy of TaylorPipe is comparable with that of SGD.

Machine learning based dynamic super twisting sliding mode controller for increase speed and accuracy of MPPT using real-time data under PSCs

Photovoltaic (PV) systems are created according to the series, parallel or series-parallel connection type of PV panels. Solar panels that form the PV system can have different irradiance values at different times of the day. This condition, which is called partial shading, causes the current and voltage values produced by the panels to fluctuate. Maximum power point tracking (MPPT) algorithms are used to ensure that PV systems operate at maximum power under all environmental conditions. MPPT algorithms are used to optimize the duty cycle of DC-DC converters in order to transfer maximum power to the load. In this study, a two-stage structure is used for MPPT. In the first stage, a reference voltage value is generated using the gaussian process regression (GPR) machine learning algorithm. In the second stage, the duty cycle of the PWM signal required for MPPT is optimized using the super twisting sliding mode controller (STSMC). The performance of the proposed method for three different scenarios is compared with the cuckoo search algorithm (CSA) from metaheuristic optimization algorithms and the perturb and observe (P&O) algorithm from classical optimization algorithms using real-time data. The software used to analyze and compare the researched methods is MATLAB/Simulink R2021b. The proposed method has performed better compared to both CSA and P&O for four conducted scenarios. Additionally, it was observed that the proposed method leads to less oscillation at the MPP point compared to P&O and CSA.

Parallel-filter-based observer control for unknown multiple narrow-band disturbance rejection

An observer-based control method with parallel Q-filter is proposed to reject unknown multiple narrow-band disturbances for line of sight stabilization in telescope systems. In general, wide-band or multiple narrow-band disturbances rejection of observer-based control can be transformed into designing Q-filter, which could be too high-order to achieve fully-accuracy digital implementation, resulting in degrading the closed-loop performance or even causing instability. Therefore, a new parallel type of Q-filters is proposed to flexibly adjust the number of Q-filter in the sensitivity function and effectively reduce the computational complexity. A sufficient condition of the effectiveness for the parallel Q-filter and the closed-loop stability is derived and verified through simulations. Furthermore, disturbance frequencies can be on-line identified to adaptively optimize the Q-filter parameters. The effectiveness of the proposed method is validated on the image-based stabilization subsystem of a segmented lightweight large-scaled diffractive telescope.

A review of research on centrifugal pendulum vibration absorber in the field of vehicle power transmission

The centrifugal pendulum vibration absorber (CPVA) is a rotating mechanical device that counteracts order-specific torque fluctuations in a rotating system by the reciprocating motion of multiple mass absorbers on a predetermined path. The downsizing of automotive engines and supercharging technologies have promoted the research and application of CPVA in drivelines. The development of CPVA is reviewed, a variety of typical CPVA structural features are described such as unifilar type, parallel bifilar type, trapezoidal bifilar type, roller type and synchronous type. The non-linear characteristics of the CPVA such as jumps and asynchronous response are discussed in detail. Mathematical methods for establishing and solving the equations of motion, the excitation of the CPVA by the gravity field, modal property analysis, the effect of the type of damping between the damper and the rotor, and the effect of manufacturing deviations on system performance are discussed. The main research results of CPVA are summarized, current research hotspots and difficulties are summarized, future development directions are proposed, and suggestions are made for future research on powertrain electrification.

Thermomechanical Behaviors of a Novel Double-Layer Corrugated Core Structure for Thermal Protection System

Corrugated core sandwich structures have great potential in the application to thermal protection system of aerospace vehicles. However, the traditional layout of web plates could inevitably lead to thermal short effects and high risk of buckling failure of the integrated thermal protection system (ITPS). In this paper, a novel double-layer ITPS is proposed by splitting and reorganizing a classical corrugated sandwich structure without additional introducing of weight. Distribution types of parallel, symmetric, and orthogonal of the double layers are designed and studied in detail. Basic theory of the thermomechanical problem as well as finite element simulation is carried out to study the responses of the ITPS. Numerical results show that the orthogonal type has more excellent yield resistance at high temperature and large temperature gradient than the others, while the parallel type has a relatively stronger buckling resistance. In addition, the structural stiffness variation caused by temperature dependencies of material parameters is greater than that caused by thermal stress, which shows the significance of consideration of temperature-dependent material properties in structure vibration analysis.

职业教育称谓的中国演进

Vocational education, as an exact academic term, originated from “Tianpin Putong Jiaoxiwen” written by Yao Wendong, the general manager of Shanxi Agriculture and Forestry School in 1904. However, the practice of vocational education as a type of education runs through the development of Chinese society, and its emergence and development have experienced a relatively long evolution process. In China, vocational education has experienced the development of traditional apprenticeship, industrial education, vocational education, technical education, and vocational and technical education. With the promulgation and implementation of the Chinese Vocational Education Law in 1996, and vocational education practice and theoretical exploration for more than 40 years since the reform and opening up, it was not until the 2014 national policy document that vocational education was finally adopted as a parallel education type of Chinese general education. Only when there is a clearer understanding of the characteristics and essential attributes of vocational education as a type of education and a consensus is reached, the dispute over the title of vocational education will gradually subside in the academic circle.

Laser percussion drilling of transparent hard and brittle materials with ring-shaped electrodes

This paper presents an innovative approach to detect plasma induced by laser drilling in a laser processing system using an external sensing electric field. The system uses a sensing electrode to detect the plasma signal, which is then sent to the controller in real-time via an embedded signal sampling rate system. The system is capable of accurately sensing the pulse repetition rate from 0 to 500 kHz during laser processing, with a signal sampling rate of up to 1 MHz. The controller analyzes the plasma signal and adjusts the laser focus position by controlling the servo motor to achieve real-time detection of laser drilling. The paper compares several configurations of electric field assistance, including parallel type interdigitated electrodes, mask type interdigitated electrodes, ring shape electrodes, and parallel type interdigitated electrodes without a steel plate. The electric field strength and power line distribution of the electric field were simulated using the COMSOL Multiphysics finite element software, and the system was tested on sapphire and quartz glass. The experimental results showed that in the presence of the electric field, the opening diameter decreased by 8 % and 12.13 %, respectively, for sapphire and quartz glass, compared to the case without the electric field. Moreover, the exit diameter increased by more than 100 % and 49.79 %, the ring shape taper angle decreased by 23.31 % and 33.74 %, the machining time decreased by 66.22 % and more than 40 %, and the opening heat affected zone decreased by 24.45 % and more than 50 %, for sapphire and quartz glass, respectively.

A mathematical model of a twin-shaft parallel flow regenerative lime kiln

ABSTRACT Lime is an important flux used in the iron and steel-making processes. Tata Steel Jamshedpur uses a twin-shaft Parallel Flow Regenerative type kiln to calcine limestone. Previously, the kiln was operated based on the temperature measurement at only three locations. This led to suboptimal kiln performance and difficulty in maintaining lime quality. A thermal digital twin was developed using first principles to address these issues. A set of unsteady-state partial-differential equations representing the thermophysical phenomena is solved numerically using the finite volume method. The model was validated with the measured flue gas temperature and lime temperatures. The model is implemented online with the real-time operating parameters to estimate the temperature profile of solid and gas and the degree of conversion of limestone. This real-time visibility enables the operators to optimize the process and achieve lime conversion up to 94%, resulting in energy savings of 31.8 GJ/day and stable lime quality.

Energy Management of P2 Hybrid Electric Vehicle Based on Event-Triggered Nonlinear Model Predictive Control and Deep Q Network

Hybrid electric vehicles (HEVs) are used as a bridge during the transition to battery electric vehicles (BEVs) and to make energy consumption more efficient. The main problem in improving the efficiency of HEV energy consumption is torque management. In this study, a novel approach based on a nonlinear model predictive controller to solve the reference tracking and torque distribution problem is proposed. That is to say, in order to increase the efficiency of torque distribution, the weights of nonlinear model predictive control (NMPC) are trained with a Deep Q Network (DQN), and an event-triggered mechanism is designed with DQN to reduce the computational cost of MPC. The considered torque distribution problem varies according to the type and structure of the HEV. In this study, a parallel type 2 hybrid electric vehicle (P2 HEV) is considered and modeled via publicly shared passenger vehicle data of the engine, motor, high-voltage battery, transmission, clutch, differential, and wheel characteristics. NMPC is formulated so that the torque values remain within the physical limits of the engine, and the battery also operates at its physical limits. Namely, it is guaranteed that the battery works according to a certain state of charge (SOC) window and current limits. The state of health (SOH) of the battery is also considered in the optimization. The motor and engine efficiencies increase by 3.61% and 2.86%, respectively, with the proposed control structure, while the computational cost is reduced by 52.01% when utilizing the proposed event-triggering mechanism in the NMPC controller.