Power Transfer Function Research Articles

Research on intelligent control system of dynamic magnetic tubular linear compressor

Abstract Addressing the cooling power control issue of linear compressors, a PID controller based on a cubic spline improved grey wolf optimization (tri-GWO) algorithm was designed. The mechanical and electromagnetic characteristics of the linear compressor were used to construct the cooling power transfer function of the linear compressor. The effects of different control algorithms on the cooling power of the linear compressor were studied in Simulink, and the response speed, settling time, and robustness of different algorithms were compared based on the simulation results. Further analysis was conducted on the impact of different algorithms in PID control. The results show that in terms of stability and robustness, the tri-GWO-PID controller has an overshoot close to 0 and quickly stabilizes at the target cooling power; in terms of tracking, the tri-GWO-PID controller exhibits the best tracking performance with the smallest cooling power deviation. The research results provide a reference for the study of cooling power control of linear compressors.

Performance Evaluation of Non-Lambertian SLIPT for 6G Visible Light Communication Systems

Visible light communication (VLC) has emerged as one promising candidate technique to improve the throughput performance in future sixth-generation (6G) mobile communication networks. Due to the limited battery capacity of VLC systems, light energy harvesting has been proposed and incorporated for achieving the simultaneous lightwave information and power transfer (SLIPT) function and for improving the overall energy efficiency. Nevertheless, almost all reported works are limited to SLIPT scenarios adopting a basic and well-discussed Lambertian optical transmitter, which definitely cannot characterize the potential and essential scenarios employing distinctive non-Lambertian optical transmitters with various spatial beam characteristics. For addressing this issue, in this work, SLIPT based on a distinct non-Lambertian optical beam configuration is investigated, and for further enhancing the harvested energy and the achievable data rate, the relevant flexible optical beam configuration method is presented as well. The numerical results show that, for a typical receiver position, compared with about 1.14 mJ harvested energy and a 31.2 Mbps achievable data rate of the baseline Lambertian configuration, a harvested energy gain of up to 1.55 mJ and an achievable data rate gain of 21.1 Mbps can be achieved by the non-Lambertian SLIPT scheme explored here.

CORTEX experiments, Part III: Experimental determination of the zero power transfer function of AKR-2 with reliable uncertainties

The transfer function is an important characteristic quantity of a nuclear reactor, since it contains the kinetic parameters. It expresses the response of a nuclear reactor to a disturbance of a certain frequency. If it is determined experimentally, it can be used to draw conclusions about the kinetic parameters. This article presents results of measurements of the zero power transfer function of the AKR-2 reactor at TU Dresden together with new data analysis methods. These measurements are compared to the theoretical zero power transfer function with kinetic parameters obtained via Monte Carlo simulations with MCNP and Serpent. To this end, advanced data analysis techniques based on a bootstrapping algorithms are employed. These techniques suppress the signal outside multiples of the fundamental frequency and additionally allow to obtain the full probability distribution of a peak in the frequency domain. This allowed for a reliable estimation of the mean value and uncertainty estimates of measured data of the zero power transfer function and the quantification of deviations between the experiments and the computations. It also made it possible to determine the phase of the zero power transfer function of AKR-2 for the first time. The experiments and computations are in agreement within the estimated uncertainties.

Fiber-optic parametric amplifier-based all-optical format conversion enabling optical networks interconnection with different modulation formats

A fiber-optic parametric amplifier (FOPA)-based all-optical format conversion (AOFC) scheme is proposed and numerically simulated to achieve optical networks interconnection with different modulation formats. In this scheme, the power transfer function (PTF) and the relative phase shift (RPS) functions between the input and output optical signals for the single-pump FOPA are derived and numerically analyzed. For the input 20 Gbps bipolar 4-ary pulse amplitude modulation (PAM4) signal, it can be converted into a BPSK signal (BPSK1) based on the power saturation characteristic of the PTF. By adjusting the input power of the input PAM4 signal, it can also be converted into a level-swapping PAM4 signal based on the single-pump FOPA. When the level-swapping PAM4 signal is sent into the single-pump FOPA with suitable power again, another BPSK signal (BPSK2) could also be generated. When the PAM4-to-BPSK format converter based on the single-pump FOPA is combined with the dual-pump FOPA (namely phase-sensitive amplifier, PSA), the 16-ary quadrature amplitude modulation (16QAM) signal can also be de-aggregated into four BPSK signals or two quadrature phase shift keying (QPSK) signals. The constellation diagrams, the power waveforms, the error vector magnitude (EVM) and the bit error rate (BER) of the relevant optical signals are measured to evaluate the scheme performance. The scheme can be deployed at the optical gateway to realize optical networks interconnection using different modulation formats.

Intra-Observer and Inter-Observer Variability of Intraocular Lens Measurements Using an Interferometry Metrology Device.

The NIMO TEMPO (Lambda-X, Nivelles, Belgium) is a novel, user-friendly and compact device designed for in vitro optical analysis of refractive and diffractive intraocular lenses (IOLs). This device analyzes the IOL wavefront and generates a synthetic eye model for numerical computation. The objective of this study was to evaluate the precision of this innovative device. Intra- and inter-observer variability were calculated using a two-way analysis of variance (ANOVA) after conducting ten measurements of eight different IOL models, with each measurement being repeated by three distinct operators (resulting in a total of 30 measurements for each IOL). The device demonstrated satisfactory intra- and inter-observer variability in evaluating IOL power and modulation transfer function (MTF) profiles, with values of 0.066 and 0.078 diopters for IOL power and 0.018 and 0.019 for MTF measurements, respectively. Furthermore, this hybrid optical and numerical in vitro IOL wavefront analyzer appears to have several advantages over conventional optical bench devices. It reduces the need for operator manipulation, and allows for numerical modeling of various optical environments, including cornea models and apertures. In conclusion, this novel metrology device designed for refractive and diffractive IOLs appears to provide a satisfactory precision, making it a promising tool in the field of IOL metrology.

In-vitro assessment of a novel intraocular lens made of crosslinked polyisobutylene

PurposeTo describe and analyse the particularities of the material and the optical quality of the first intraocular lens (IOL) (Eyedeal® lens) made of crosslinked polyisobutylene (xPIB). MethodsWe assessed the material quality using an accelerated ageing process (to provoke glistenings) and compared values with a control, AcrySof® lens. Using the sessile drop method, the contact angle of the new IOL was measured. Images of the lens surface were recorded by scanning electron microscopy (SEM). Optical quality was assessed by measuring the labeled power and modulation transfer function (MTF) using standard metrology equipment (OptiSpheric IOL PRO2). ResultsThe Eyedeal® lens had an average glistening density result of 7.46 ± 3.78 MV/mm2 compared to the control AcrySof® whose glistenings number was 142.42 ± 72.47 MV/mm2. The contact angle was 97.2° whereas the angle of AcrySof material is between 73.3 ± 2.4° and 84.4 ± 0.1°. Using SEM, Eyedeal® lenses were examined and all appeared to be comparable to modern IOLs made of acrylic materials. The power and MTF values were normal and conformed to ISO standards. ConclusionsIn the laboratory, the new Eyedeal® lens showed equivalence to current hydrophobic- or hydrophilic-acrylic lens models. It showed superiority in its glistening density result compared to the control lens.

Attitude modeling of star trackers under complex vibration conditions

The attitude vibration of a carrier has a significant effect on the installed star tracker. However, this effect has not been sufficiently studied. In this paper, the attitude model of a star tracker is investigated under complex vibration conditions. First, a star spot motion model applicable to complex angular motion is constructed. Then, the linearization conditions of the model are presented. Based on the linearized model, sinusoidal and random vibrations are analyzed, and an attitude model is established. The proposed attitude model provides the modulation factor of the response to sinusoidal vibrations and the power transfer function of the response to random vibrations and also elaborates on the synthesis mechanism between the responses to a complex vibration and its components. Simulations and ground experiments were conducted, and the results show that the maximum relative error was 6.66% and 3.82% for sinusoidal and random vibrations, respectively.

Flexible All-Optical 8QAM Signal Format Conversion Using Pump Assisted Nonlinear Optical Loop Mirror

A flexible all-optical format interconversion scheme based on a pump assisted nonlinear optical loop mirror (NOLM) is proposed and numerically simulated for the first time to our knowledge. In this scheme, input multi-Gbps 8QAM signals are divided into clockwise (CW) and counter-clockwise (CCW) components by a 3-dB optical coupler (OC), which also couples light from the input pump into the NOLM from the CCW direction. The numerical model of the pump assisted NOLM with CW and CCW optical paths is simplified using a nonlinear Mach-Zehnder interferometer (MZI). Optical signals in the upper MZI arm will be mainly affected by the self-phase modulation (SPM) effect when traversing the highly nonlinear fiber (HNLF) and those in the lower MZI arm are impacted by cross-phase modulation (XPM) in addition to SPM when they experience the HNLF with the input pump light. When the upper-arm optical signal with SPM phase shift and the lower arm optical signal with SPM and XPM phase shifts are coherently mixed, a new converted 8QAM signal can be obtained. The power transfer function (PTF) of the pump assisted NOLM and the relative phase shift (RPS) between the input and the output optical signals are theoretically provided and verified. By only changing the input power of the 8QAM signal and the pump light, all-optical format interconversion of square-, standard- and star-shaped 8QAM signals can be achieved. Furthermore, the proposed scheme can achieve format conversion from the 30 Gbps square-shaped 8QAM signal to a 20 Gbps quadrature phase shift keying (QPSK) signal. The scheme performance is analyzed via constellation diagrams, eye diagrams, the error vector magnitude (EVM) and the bit error rate (BER) of the optical signals. The scheme developed can be deployed in optical gateways to connect different optical networks by dynamically selecting their appropriate modulation formats.

Exploring the Signal Filtering Properties of Idealized Watersheds Using Spectral Analysis

Watersheds act as low-pass filters, damping and attenuating climatic signals as water moves through the surface and subsurface. This is a well observed phenomenon; however, the ways in which watershed properties control the nature of this filtering are less well documented, especially with respect to groundwater surface water interactions. Here, we use a physically based groundwater surface water model to simulate idealized hillslope ensembles with varying watershed properties (hillslope slope, hydraulic conductivity, and precipitation magnitude) to quantitively explore the impact of watershed configuration on temporal filtering in both the surface and subsurface. To limit the complexities of this system an idealized titled-v domain is used. Multi-decadal simulations (95 years) are run, and then power spectral densities and transfer functions are used to quantify the temporal dynamics and damping of each simulation. Overall, we show that the degree of filtering and the degree of signal transformation is controlled by the total time spent in the subsurface and the degree of groundwater surface water exchanges. The ratio of precipitation to hydraulic conductivity controls the partitioning between infiltration and runoff. Greater infiltration results in less filtering in the subsurface and more filtering in streamflow. For a given precipitation conductivity ratio, deeper water table depths lead to greater streamflow filtering for periods less than 5 years. For time periods greater than 5 years the streamflow filtering is most strongly related to hydraulic conductivity which controls the baseflow dynamics. The majority of the input signal is filtered in the subsurface for short periods less than one year. For longer time scales, hydraulic conductivity is found to be the primary control of filtering and power shift taking place in the subsurface with larger conductivities correlated to less filtering and less of a signal transformation. Deeper water table depths lead to more signal transformation in saturated storage but are not correlated to filtering in unsaturated storage. This is likely due to counteracting effects of higher conductivity (which decreases filtering) and deeper water table depths (which increase filtering).

Beamforming Design for Integrated Sensing and Wireless Power Transfer Systems

This letter proposes a new concept of integrated sensing and wireless power transfer (ISWPT), where radar sensing and wireless power transfer functions are integrated into one hardware platform. ISWPT provides several benefits from the integrating operation such as system size, hardware cost, power consumption, and spectrum saving, which is envisioned to facilitate future 6G wireless networks. As the initial study, we aim to characterizing the fundamental trade-off between radar sensing and wireless power transfer, by optimizing transmit beamforming vectors. We first propose a semi-definite relaxation-based approach to solve the corresponding optimization problem globally optimal, and then provide a low-complexity sub-optimal solution. Finally, numerical results verify the effectiveness of our proposed solutions, and also show the trade-off between radar sensing and wireless power transfer.

Design of Mode-Locked Fibre Laser with Non-Linear Power and Spectrum Width Transfer Functions with a Power Threshold

There is a growing demand for higher computational speed and energy efficiency of machine learning approaches and, in particular, neural networks. Optical implementation of neural networks can address this challenge. Compared to other neuromorphic platforms, fibre-based technologies can unlock a wide bandwidth window and offer flexibility in dimensionality and complexity. Moreover, fibre represents a well-studied, low-cost and low-loss material, widely used for signal processing and transmission. At the same time, mode-locked fibre lasers offer flexibility and control, while the mode-locking effect can be crucial for unlocking ultra-short timescales and providing ultra-fast processing. Here, we propose a mode-locked fibre laser with a non-linear power threshold in both power and spectrum. The advantage of the proposed system is a spectrum width two-branch function dependent on the input signal power. The effect is caused by a transition between two operating regimes and is governed by the input signal power. The proposed design enables receiving a non-linear transfer function in amplitude with a power threshold as an optical analogue of biological neurons with the additional advantage of a non-linear two-branch transfer function in spectrum width. The latter property is similar to the frequency-varied response dependent on stimulus properties in biological neurons. Thus, our work opens new avenues in research into novel types of artificial neurons with a frequency spectrum width variable response and, consequently, spiking neural networks and neural-rate-based coding with potential applications in optical communications and networks with flexible bandwidth, such as 5G and emerging 6G.

An ultrasound-induced wireless power supply based on AlN piezoelectric micromachined ultrasonic transducers

Wireless power transfer is one of the enabling technologies for powering implantable biomedical devices. Biocompatibility and CMOS compatibility of wireless power transfer devices are highly desired due to safety and footprint concerns. Toward implantable applications, this paper presents an ultrasound-induced wireless power supply based on AlN piezoelectric micromachined ultrasonic transducer (PMUT). The wireless power supply integrates wireless power transfer, power management and energy storage functions. The PMUT array is used as a passive wireless power receiver, followed by electrical impedance matching networks and a voltage multiplier for efficient power transmission and rectification. The output power intensity of the wireless receiver reaches 7.36 μW/mm2 with an incident ultrasound power below the FDA safety limit. The output power of the wireless power supply reaches 18.8 μW and a 100-μF capacitor is fully charged to 3.19 V after power management, which are sufficient to power many low-power implantable biomedical devices such as for neural electrical stimulation, biosensors and intrabody communication applications. The wireless power supply is implemented in a PCB with a diameter of 1 cm. With biocompatibility and CMOS compatibility of AlN thin film compared to commonly used PZT, the proposed solution paves the way for safer and ultraminiaturized wireless power supplies with further development incorporating all the functions on a monolithic chip in the future.

A Method for Improving the Technique for the Synthesis of Quasi-two Bandpass Matching Devices

The article deals with issues related to the possibilities of the analytical technique for the synthesis of quasi-two-band matching devices and the way to improve it. The technique is based on the mathematical apparatus of the Generalized Darlington method with the use of a special method of forming quasi-two-band frequency characteristics at the stage of choosing an approximating function. A comparison of the results of load matching obtained using the developed methodology and a progressive numerical synthesis method is presented. The analysis of the solved problem allowed us to make a private assessment of the capabilities of the proposed analytical method of matching. An important limiting circumstance for the synthesis technique is indicated – the lack of solutions for loads of increased complexity, which is caused by a small variability of the known approximating power transfer functions. As a solution to the problem, boundedly flat functions are considered, which differ from classical approximations in their extended variability. The use of a combination of knowledge about the formation of quasi-two-band frequency characteristics and the technique of using limited-flat functions made it possible to expand the range of matched loads. A solution to the test problem of matching a 5-element load is presented, for which the use of classical approximations is not acceptable.

Keep it simple: A right conical infrasound windscreen from off-the-shelf components

Windscreens for higher frequency infrasound are a continued topic of discussion because the ideal has yet to be found, i.e., an inexpensive, easily shipped, compact windscreen with a flat 3 Hz to >20 Hz passband and nearly zero transmission loss. Recent research has shown that the robust porous hose, porous fabrics, and perforated metal domes are capable of filling many of those needs. However, each technology has drawbacks that necessitate further research to arrive at a greater understanding of the windscreen and to approach the ideal. Guided by this previous infrasound windscreen research, a right conical windscreen was constructed from easily obtained commercial products and subsequently tested beside previously characterized windscreens. The presentation will discuss results of the experimental program to include comparisons of power spectral densities and transfer functions.

Photonic time-stretch based on phase modulation for sub-octave applications.

Photonic time-stretch (PTS) has been extensively studied due to its great potential in analog-to-digital converters. Here, we propose and demonstrate a PTS system based on phase modulation for sub-octave applications. Different from the PTS system using a Mach-Zehnder modulator (MZM), the PTS system, which uses a phase modulator (PM), has an operation bandwidth within an octave and is more suitable for preprocessing of sub-octave signals. Within the sub-octave band, the system is free of all second-order spurious signals. Because there is no direct current bias in a PM, the problem of bias drift, as well as the nonlinear distortion caused by it, can be thoroughly avoided. In addition, based on phase modulation and direct detection, the proposed PTS system has higher stability and a more simplified structure than that based on coherent detection. An exact analytical model has been established, and some compact expressions have been derived to fully characterize all frequency components of the PM-based PTS system. System properties, including the power transfer function, 3-dB bandwidth, and nonlinear distortion have been discussed, and numerical and experimental results on the performance of the PM-based PTS have been presented. In addition, a dual-channel PTS that employs a PM and a push-pull MZM has been proposed to extend the operation bandwidth to multi-octave.

PV Modules Interfacing Isolated Triple Active Bridge for Nanogrid Applications

DC nanogrid architectures with Photovoltaic (PV) modules are expected to grow significantly in the next decades. Therefore, the integration of multi-port power converters and high-frequency isolation links are of increasing interest. The Triple Active Bridge (TAB) topology shows interesting advantages in terms of isolation, Zero Voltage Switching (ZVS) over wide load and input voltage ranges and high frequency operation capability. Thus, controlling PV modules is not an easy task due to the complexity and control stability of the system. In fact, the TAB power transfer function has many degrees of freedom, and the relationship between any of two ports is always dependent on the third one. In this paper we analyze the interfacing of photovoltaic arrays to the TAB with different solar conditions. A simple but effective control solution is proposed, which can be implemented through general purpose microcontrollers. The TAB is applied to an islanded DC nanogrid, which can be useful and readily implemented in locations where the utility grid is not available or reliable, and applications where isolation is required as for example More Electric Aircraft (MEA). Different conditions have been simulated and the control loops are proved for a reliable bus voltage control on the load side and a good maximum power point tracking (MPPT).

A Novel Mode-Stirred Reverberation Chamber Design for 5G Millimeter Wave Bands

A novel mode-stirred reverberation chamber (RC) is designed and analyzed for millimeter wave bands. The size of the proposed RC with dimensions of 0.9 m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times0.9$ </tex-math></inline-formula> m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times1.1$ </tex-math></inline-formula> m is suitable for user equipment (UE) tests. Two Z-shaped mode-stirrers are applied to generate a uniform field. To fulfill the communication and test requirements for user equipment, reference, measurement and link antennas with a large bandwidth are utilized, which can support both the frequency range (FR) 1 and FR2 bands of the 5G spectrum. The lowest usable frequency (LUF) and mode density were first calculated and examined. Then, the power transfer function (PTF) from 2 GHz to 40 GHz was obtained to verify the path loss. Three measurement campaigns were carried out to verify the accuracy of the RC. Firstly, the transmission power of the passive antenna for a conductive test was compared with the RC over the air (OTA) total radiated power (TRP) for single-tone signals. Then, signals with bandwidths of 100 MHz and 400 MHz were applied. A maximum power difference of only 0.8 dB was found in the above two experiments. Furthermore, the TRP for the same commercial 5G UE in both RC and compact antenna test range (CATR) systems was measured and compared. To the best of the authors’ knowledge, this is the first work to provide TRP results for 5G millimeter wave bands in a RC. The test results show that the TRP values for the two systems are almost the same with a maximum deviation of 0.5 dB, while the time required to carry out tests using the RC is lower than that for the CATR system.

Study of suspension systems for experimental tanks of the USSR in the second half of the 20th century

Modern pneumohydraulic suspension systems for high-speed tracked vehicles have fairly typical versions of kinematic schemes, implying the installation of an elastic-damping element directly on the suspension housing (inside or outside). This solution is structurally relatively simple, and it is understood that it allows to reduce the values of unsprung masses. Other options, with placement of elastic and damping elements inside the guide elements (balancers), did not “take root” due to the greater structural complexity of both elastic or damping element and the suspension guide element. In addition to the structural complexity of implementation, such a solution increases the values of unsprung masses and, most importantly, complicates the organization of the cooling system. The protruding elements of the chassis are clogged with soil, snow (mud) when driving, which acts as a heat insulator. Nevertheless, with modern technological capabilities, these difficulties can be overcome to a certain extent, in whole or in part. However, despite the above disadvantages, this solution also has important advantages: the suspension does not take up space in the reserved volume, but is completely inside the tracked bypass, which allows using the housing volume more efficiently, and, in addition, providing the most successful bottom design for protection from mine detonation (in the case of a heavy tank “Object 279”, this also made it possible to significantly increase the cross-country ability). This article provides an overview of Soviet prototypes of heavy and rocket tanks, which suspension system was implemented in the guide element. The article also presents a method for determining the power and kinematic transfer functions for these suspension options, analyzes the design implementations and shows that the characteristics of the elastic elements of experimental vehicles meet modern requirements for the suspensions of high-speed tracked vehicles.

Optimization method for universal NOLM-based phase-preserving amplitude regenerator with application to Att-NALM scheme

We theoretically investigate the conditions of achieving phase-preserving amplitude regeneration for the universal nonlinear optical loop mirror (NOLM) structure and present a method of determining the optimal working point for amplitude shaping. A normalized amplitude-phase transfer parameter is introduced to measure the phase-preserving performance at the working points of multilevel regeneration. Then, a new NOLM (so-called Att-NALM) structure, consisting of an optical attenuator and a bidirectional optical amplifier, is taken into account by the optimization method. The optimal working point can respectively be designed on the first or second plateau of the optical power transfer function for phase-preserving and amplitude regeneration of QPSK/8PSK or two-amplitude 8QAM signal. Our simulation shows that, the corresponding error vector magnitude (EVM) has a maximal reduction with the noise reduction ratio of 5.44dB, 4.7dB and 3.7dB for only amplitude noise, and 1.86dB, 1.58dB and 1.4dB for simultaneous amplitude and phase noise, respectively. We also list the design parameters of the existing NOLM structures for phase-preserving amplitude regeneration.

Research on SOC balance strategy of STEKF battery based on MMC-BESS model

Under the condition of the battery current fluctuation and the uncertain initial value of the battery SOC in the MMC(Modular Multilevel Converter) battery energy storage system, there are relatively big errors in the prediction of SOC estimation values and there are poor results of the battery SOC balance, by using the ampere-hour integration method and the open-circuit voltage method. The method of model prediction was adopted to study the SOC balance strategy. Firstly, the power transfer function between each port is derived and the second-order Thevenin equivalent nonlinear model of the battery is established. On this foundation, the more accurate estimation results of the battery SOC are obtained employing the strong tracking extended Kalman filter algorithm, under the condition of the large fluctuation of the battery current and the uncertainty initial value of the battery SOC in the MMC-BESS model. In the end of the paper, the validity of the method introduced in the paper way was confirmed according to the simulation results of the simulation calculation based on the power transfer relationship between the battery SOC and each port, using the three-level SOC balance strategy to balance the battery SOC.