Power Transfer Function Research Articles

Creation of a refractive lens within an existing intraocular lens using a femtosecond laser

To assess the efficiency and effectiveness of the technology that creates a hydrophilicity-based refractive index change within a standard intraocular lens (IOL) to alter the refractive characteristics of the IOL. Perfect Lens LLC, Irvine, California, USA. Experimental study. The IOL used in this experiment was a standard hydrophobic model (EC-1Y). The refractive index of the material was changed by exposure of the material to a femtosecond laser and the subsequent absorption of water by the material. An experimental system using a femtosecond laser, an acoustic-optic modulator, beam-shaping optics, a scan system, and an objective lens was used to create the refractive index change within the IOL. Experiments were performed to determine the optimum wavelength, energy per pulse, and line spacing to produce the refractive index shaping lens. A power and modulation transfer function (MTF) measurement device for refractive and diffractive IOLs was used to measure the diopter and MTF before and after the creation of the refractive index shaping lens. The technology successfully altered the refractive characteristics of the IOL. The refractive index change altered the diopter (D) of the IOL (to within ±0.1 D of the targeted change) without significant diminution in the MTF (<0.1 or MTF ≥0.51 for the 100 lp/mm measurement). The refractive properties of an IOL can be altered by building a refractive index shaping lens within an IOL using a femtosecond laser with minimal diminution in MTF. All authors are employed by Perfect Lens, LLC and have a financial interest in the products of Perfect Lens, LLC.

Forecast of intense near- and mid-IR laser radiation propagation along slant atmospheric paths

The effectiveness of the use of intense radiation from different near- and mid-IR laser sources propagating along high-altitude slant optical paths is numerically estimated on the basis of the optical model of the Earth’s atmosphere developed by the authors. Different laser sources, including chemical oxygeniodine laser (COIL), chain chemical DF laser, and carbon-monoxide (CO) laser are considered with different optical weather conditions taking into account linear and nonlinear optical effects. A COIL source is shown to be the most preferable in terms of the total laser power transmitted along a path, because of weak atmospheric attenuation and minimal effects of nonlinear factors. In addition, this laser source shows the best performance in terms of the mean radiation intensity at a receiver. Among chemical multiwavelength lasers, DF lasers lead in terms of the power transfer function.

Design of all-optical multi-level regenerators based on Mach–Zehnder interferometer

We propose a design method for all-optical multi-level regenerators by mimicking the normalized power transfer function (PTF) in the first-order approximation to the ideal step-like PTF, in which a key step is to appropriately select the amplitude and phase conditions of Mach–Zehnder-interferometer (MZI)-based regenerators. As an example, we describe the design process of the self-phase-modulation (SPM)-based MZI regenerator constructed by a section of nonlinear fiber and an optical phase shifter (OPS). It is shown that the parameter of reference power level (RPL) can be regarded as the upper limit of input power, which is useful for the measure of the multi-level regeneration performance. The number of regenerative power levels increases with the RPL parameter. For 4-level pulse amplitude modulated (4PAM) optical signals degraded by the Gaussian noises with the standard deviation of 0.02, the SPM-based MZI regenerator has an average noise reduction ratio (NRR) of 6.5dB, better than that of 1st-order regenerator by about 5dB.

Placement optimization of integrated circuits for reduced radio-frequency interferences in mobile devices

In this article, an optimization procedure for the placement of integrated circuits (ICs) for reduced radio-frequency interference (RFI) in mobile devices is presented. The concept of a power conversion factor (PCF) is introduced to quantify the near-field radiation of ICs based on near-field measurement techniques. For PCF extraction, equivalent source antennas are designed to represent the radiation chracteristics of ICs. In addition, the concept of a power transfer function (PTF) is also introduced to characterize the near-field propagation from RFI noise sources to the built-in antennas in mobile devices. From the combination of the PCFs and the PTFs, a spatial near-field specification of ICs for reduced RFI is proposed. Based on the proposed specification, the application example of an optimized IC placement in mobile platform design is presented. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:31–37, 2016

Basic Analysis of Two‐Coils Structure Based on Magnetically‐Coupled Resonant Technology for SWIPT Application

The Magnetically-coupled resonant (MCR) technology is exploited in this paper to realize Synchronous wireless information and power transfer (SWIPT) function, which means that the power carriers also transmit information. The circuit structure of SWIPT system is analyzed and the existence of two optimal frequencies in power efficiency under small resistance circumstance is proved. The physical parameters having influences on the two optimal frequencies are discussed, such as the distance between coils, impedance characteristics of coils and loads. These results provide a way to increase the bandwidth of MCR technology, while maintaining high power efficiency to realize SWIPT function. Simulations and experimental results are presented to verify the feasibility of the proposed system and obtained theoretical expressions.

Proximity‐effect test for lossy wireless‐device measurements in reverberation chambers

The authors present a test method for quantifying and reducing systematic errors arising from antenna proximity to lossy objects in over-the-air performance testing of lossy large-form-factor wireless devices. The method determines the extent to which antenna proximity to lossy, large-form-factor objects influences the measured reference power transfer function. The test may be used to pre-characterise a given chamber set-up in terms of a minimum distance between antennas and lossy objects. They illustrate the use of the method in a total radiated power measurement of a large, commercially available, machine-to-machine device, where agreement to anechoic-chamber measurements is demonstrated to within the measurement uncertainty.

Cosmological structure formation in Decaying Dark Matter models

The standard cold dark matter (CDM) model predicts too many and too dense small structures. We consider an alternative model that the dark matter undergoes two-body decays with cosmological lifetime τ into only one type of massive daughters with non-relativistic recoil velocity Vk. This decaying dark matter model (DDM) can suppress the structure formation below its free-streaming scale at time scale comparable to τ. Comparing with warm dark matter (WDM), DDM can better reduce the small structures while being consistent with high redshfit observations. We study the cosmological structure formation in DDM by performing self-consistent N-body simulations and point out that cosmological simulations are necessary to understand the DDM structures especially on non-linear scales. We propose empirical fitting functions for the DDM suppression of the mass function and the concentration-mass relation, which depend on the decay parameters lifetime τ, recoil velocity Vk and redshift. The fitting functions lead to accurate reconstruction of the the non-linear power transfer function of DDM to CDM in the framework of halo model. Using these results, we set constraints on the DDM parameter space by demanding that DDM does not induce larger suppression than the Lyman-α constrained WDM models. We further generalize and constrain the DDM models to initial conditions with non-trivial mother fractions and show that the halo model predictions are still valid after considering a global decayed fraction. Finally, we point out that the DDM is unlikely to resolve the disagreement on cluster numbers between the Planck primary CMB prediction and the Sunyaev-Zeldovich (SZ) effect number count for τ ∼ H0−1.

The interplay between the measured dimension and temperature of hot large forgings

During the forming process of hot forgings, the dimension and temperature are key parameters for improving the forging technology. In the paper, based on the mathematical physics methods, a mutual relationship model between the measured dimension and the temperature is proposed. This relationship model is displayed by the temperature field model and the dimensional model. Firstly, according to the law of conversation of energy, using the Dirichlet function and the measured dimension, the power-transfer function of heat source is established. Taking the measured temperatures as the boundary conditions, the temperature field model influenced by the dimensional change is established using the method of the moving virtual heat source. Secondly, based on the variation characteristics between the mesoscopic structure and the stress, using the function of the deformation energy is analyzed. Using the differential calculus of the pluralistic function, the dimensional change model influenced by the measured temperature is established. Based on the temperature field model and the dimensional model, this mutual relationship of the two ones can be clearly and directly displayed. Finally, the verifiable experiments and simulations are obtained using the forging experiments and the Deform-3D. Using the contrastive analysis method, the feasibility of the two relationship models is verified and the change trends of the dimension and temperature are analyzed. Combining the parameters of the forging technology in the thermal forming process, the application and the practical significance of the model are further cleared. The mutual relationship model provides a theoretical basis for improving the forging technology.

Experimental estimation of the delayed neutron fraction βeff of the MAESTRO core in the MINERVE zero power reactor

A method for determining the effective delayed neutron fraction βeff using in-pile reactivity oscillations and Fourier analysis is presented. This method is based on measurements of the reactor's power response to small periodic in-pile reactivity perturbations and utilizes Fourier analysis for reconstruction of the reactor zero power transfer function. This approach enables the estimation of βeff using multi-parameter nonlinear weighted least-squares fit. The method extends previous works by accounting for higher harmonics excitation in the frequency domain by the trapezoidal reactivity signal, both in the reactivity perturbation and in the reactor power response. We show that by using this new approach it is possible to obtain the reactor transfer function in a wide range of frequencies, using only a single oscillation frequency. This method is applied to a set of measurements of the MAESTRO core configuration in the MINERVE zero power reactor (ZPR) located at the Cadarache Research Center. The derived value of βeff, using this method, is 711 ± 17 pcm.

Analysis and Performance Improvement of Independent Electric Coupled Resonance WPT System with Impedance Transformer

Wireless power transfer (WPT) technology is expected for the next generation power feeding system, which could supply the power to portable devices without any wires. Compare to the magnetic coupled resonance; a WPT system uses electric coupled resonance could provide a higher position of flexibility. In this paper, the concepts of independent electric coupled resonance type WPT system is investigated by using equivalent circuit including: power transfer function, critical coupling point, frequency splitting and optimum port impedance. After a pair of matching loops are added into source and receive side, the power transfer efficiency could has a great improvement is confirmed by using simulation and experiment.

Body-to-Body Indoor Channel Modeling at 2.45 GHz

This paper presents an indoor Body-to-Body narrowband channel model based on experimental data, acquired through a real-time dynamic measurement campaign at 2.45 GHz. The radio channel was investigated under different communication conditions, according to the movement performed by some human subjects and to their mutual position. Several node locations were considered, and two antenna types were used to assess the impact of their radiation characteristics on channel properties. For each investigated link, the channel power transfer function was modeled as composed by a channel gain and a small-scale fading contribution, the latter arising from the multipaths due to the environment and the human's motion. The shadowing effect of the body was also evaluated considering that the body itself can act as an obstacle to the communication, according to its spatial orientation. Every model component was characterized for each scenario, highlighting how a specific movement results in different effects on channel dynamic properties.

Accelerated general method for computing noise effects in arrays

Noise in an acoustic array can be defined as any unwanted signal, and understanding how noise interacts with a structural system is paramount for optimal design. For example, in an underwater vehicle we may want to understand how structural vibrations radiate through a surrounding fluid; or an engineer may want to evaluate the level of sound inside a car resulting from the turbulent boundary layer (TBL) induced by a moving vehicle. This talk will discuss a means of modeling noise at a point of interest (e.g., at a sensor location) stemming from a known source by utilizing a power transfer function between the source and the point of interest, a generalization of the work presented in [1]. The power transfer function can be readily computed from the acoustic response to an incident wave field, requiring virtually no additional computation. The acoustic solution may be determined via analytic frequency domain approaches or through a finite element analysis, enabling the noise solution to be a fast post processing exercise. This method is demonstrated by modeling the effects of a TBL pressure and noise induced by structural vibrations on a sensor array embedded in an elastic, multi-layer solid. Additionally, uncertainties in the noise model can be easily quantified through Monte Carlo techniques due to the fast evaluation of the noise spectrum. Ko, S.H. and Schloemer, H.H. “Flow noise reduction techniques for a planar array of hydrophones,” J. Acoust. Soc. Am. 92, 3409 (1992).

Cosmo++: An object-oriented C++ library for cosmology

This paper introduces a new publicly available numerical library for cosmology, Cosmo++. The library has been designed using object-oriented programming techniques, and fully implemented in C++. Cosmo++ introduces a unified interface for using most of the frequently used numerical methods in cosmology. Most of the features are implemented in Cosmo++ itself, while a part of the functionality is implemented by linking to other publicly available libraries. The most important features of the library are Cosmic Microwave Background anisotropies power spectrum and transfer function calculations, likelihood calculations, parameter space sampling tools, sky map simulations, and mask apodization. Cosmo++ also includes a few mathematical tools that are frequently used in numerical research in cosmology and beyond. A few simple examples are included in Cosmo++ to help the user understand the key features. The library has been fully tested, and we describe some of the important tests in this paper. Cosmo++ is publicly available at http://cosmo.grigoraslanyan.com.

Nonlinear polarization dependence of fiber polarization diversity systems

The nonlinear polarization dependence (NPD) of a fiber polarization diversity system (PDS) is studied by means of the nonlinear power transfer functions (PTFs) of two orthogonally polarized beam paths (PBPs). In principle, a polarization-independent PDS can be developed when the PTF curves are centrally symmetric to each other in a certain range of input power. As an example, a data-pump four-wave-mixing-based PDS is investigated by simulation and experiment, and the probe and pump powers are optimized for the minimal NPD. Experimental results show that, by adding a power-saturated erbium-doped fiber amplifier to the PDS, the dynamic range of input power can be increased up to 26dB, along with 4dB extinction ratio (ER) improvement.

Background-free pulsed microwave signal generation based on spectral shaping and frequency-to-time mapping

A novel scheme for the generation of background-free pulsed microwave signals is proposed and experimentally demonstrated based on spectral shaping, frequency-to-time mapping, and balanced photodetection. In the proposed scheme, the optical spectral shaper, which consists of a differential group delay (DGD) element, two polarization controllers, and a polarization beam splitter, has two outputs with complementary power transfer functions. By passing a short optical pulse through the spectral shaper and a dispersive element (DE), a pulsed microwave signal is obtained after balanced photodetection. Thanks to the balanced photodetection, the low-frequency components (i.e., the background signal) in the electrical spectrum is suppressed, leading to the generation of a background-free pulsed microwave signal. Meanwhile, the spectral power of the obtained microwave signal is enhanced compared to that obtained by single-end detection. Experimental results for the generation of a pulsed microwave signal centered at 12.46 GHz show that the background signal can be suppressed by more than 30 dB, and the spectral power is increased by 5.5 dB. In addition, the central frequency of the obtained background-free pulsed microwave signal can be tuned by changing the DGD introduced by the DGD element, and/or by changing the dispersion of the DE.

The Structure Design and Simulation of the Ring Resonator Based on SOI Planar Optical Waveguide for the Micro Biochemical Sensor

A ring resonator based on Silicon-on-Insulator (SOI) planar optical waveguide for micro biochemical sensor application is designed and simulated in this paper. The SOI optical waveguide is made with a ridge structure. According to the optical waveguide mode theory and the performance of the ring resonator, the size of the single mode ridge waveguide and the structure of the ring resonator are obtained. Based on the structure principle and the transmission mechanism of electric field of the ring resonator, the power transfer function and the parametric equation of sensitivity are derived. As a result, the value of Q of the ring resonator can reach 103 magnitudes. At last, the structure and the transmission mechanism of electric field in the ring resonator are simulated in MATLAB software.

Interindividual relationships between blood pressure and cerebral blood flow variability (1184.11)

The relationships between blood pressure variability (BPV) and cerebral blood flow variability (CFV) are poorly understood. This study sought to characterize the interindividual characteristics between spontaneous BPV and CFV across individuals with intact cerebrovascular control. We analyzed blood pressure and flow velocity data from 105 healthy subjects. Spontaneously occurring fluctuations in mean arterial blood pressure (MAP) and middle cerebral artery flow velocity (MCAvmean; Transcranial Doppler ultrasound) were characterized using power spectral and transfer function analysis in the very low‐ (0.02‐0.07 Hz), low‐ (0.07‐0.20 Hz), and high‐frequency (0.20‐0.40 Hz) ranges. Across our study sample, MAP was a positive predictor of MCAvmean to varying degrees in all three frequency ranges (Very Low Frequency (R2= 0.088, P&lt; 0.01) Low Frequency (R2= 0.47, P&lt; 0.01), High Frequency (R2 = 0.55, P&lt; 0.01)). The increased predictive power of MAP for MCAvmean in higher frequencies demonstrates that BPV is a determinant of CFV. However, factors other than BPV are influential, especially in the very low frequencies. These results demonstrate that intermittent blood pressure, a clinical measurement predominantly representative of very low frequency BPV content, is an inadequate surrogate of cerebral perfusion variability.

Estimation of Transferred Power from a Noise Source to an IC with Forwarded Power Characteristics

This paper proposes an accurate approach for predicting transferred power from a noise source to integrated circuits based on the characteristics of the power transfer network. A power delivery trace on a package and a printed circuit board are designed to transmit power from an external source to integrated circuits. The power is demonstrated between an injection terminal on the edge of the printed circuit board and integrated circuits, and the power transfer function of the power distribution network is derived. A two-tier calibration is applied to the test, and scattering parameters of the network are measured for the calculation of the power transfer function. After testing to obtain the indispensable parameters, the real received and tolerable power of the integrated circuits can be easily achieved. Our proposed estimation method is an enhancement of the existing the International Electrotechnical Commission standard for precise prediction of the electromagnetic immunity of integrated circuits.

Flow–plant interactions at leaf, stem and shoot scales: drag, turbulence, and biomechanics

Flow–plant interactions are experimentally investigated at leaf, stem, and shoot scales in an open-channel flume at a range of Reynolds numbers. The experiments included measurements of instantaneous drag forces acting on leaves, stems, and shoots of the common freshwater plant species Glyceria fluitans, complemented with velocity measurements, high-resolution video recordings, and biomechanical tests of leaf and stem properties. The analyses of bulk statistics, power spectral densities, transfer functions, and cross-correlations of measured velocities and drag forces revealed that flow characteristics, drag force, and plant biomechanical and morphological properties are strongly interconnected and scale-dependent. The plant element–flow interactions can be subdivided into two classes: (I) passive interactions when the drag variability is due to the time variability of the wetted and frontal areas and squared approach velocity (due to the large-scale turbulence); and (II) active interactions representing a range of element-specific instabilities that depend on the element flexural rigidity and morphology. Implications of experimental findings for plant biophysics and ecology are briefly discussed.

On-body TOA-based ranging error model for motion capture applications within wearable UWB networks

We present herein an error model that characterizes on-body range measurements based on time of arrival (TOA) estimation in Impulse radio-ultra wideband, wireless body area networks. Considering real channel measurements over two representative on-body links for repeated walk cycles, the model is drawn as a conditional mixture, accounting for signal to noise ratio (SNR) variations and non line of sight (NLOS) channel obstructions caused by the body. Key model parameters are then investigated as a function of the previous obstruction and SNR configurations, illustrating missed/false path detection effects at low SNR. On this occasion, two TOA estimators are compared, namely a strongest path detection scheme through matched filtering and a first path detection scheme relying on high-resolution channel estimation. Finally, we discuss the possibility to generalize the previous model to any kind of on-body link, based on empirical observations regarding the dynamic range of the channel power transfer function under mobility. Accordingly, the resulting final model could integrate basic elements of classification, such as the instantaneous LOS/NLOS and static/dynamic link status.