Harmonic Energy Research Articles

A comparison theorem for cosmological lightcones

Let (M, g) denote a cosmological spacetime describing the evolution of a universe which is isotropic and homogeneous on large scales, but highly inhomogeneous on smaller scales. We consider two past lightcones, the first, {{mathcal {C}}_{L}^{-}}(p, g), is associated with the physical observer pin ,M who describes the actual physical spacetime geometry of (M, g) at the length scale L, whereas the second, {mathcal {C}_{L}^{-}}(p, hat{g}), is associated with an idealized version of the observer p who, notwithstanding the presence of local inhomogeneities at the given scale L, wish to model (M, g) with a member (M, hat{g}) of the family of Friedmann–Lemaitre–Robertson–Walker spacetimes. In such a framework, we discuss a number of mathematical results that allows a rigorous comparison between the two lightcones {mathcal {C}_{L}^{-}}(p, g) and {mathcal {C}_{L}^{-}}(p, hat{g}). In particular, we introduce a scale-dependent (L) lightcone-comparison functional, defined by a harmonic type energy, associated with a natural map between the physical {mathcal {C}_{L}^{-}}(p, g) and the FLRW reference lightcone {mathcal {C}_{L}^{-}}(p, hat{g}). This functional has a number of remarkable properties, in particular it vanishes iff, at the given length-scale, the corresponding lightcone surface sections (the celestial spheres) are isometric. We discuss in detail its variational analysis and prove the existence of a minimum that characterizes a natural scale-dependent distance functional between the two lightcones. We also indicate how it is possible to extend our results to the case when caustics develop on the physical past lightcone {mathcal {C}_{L}^{-}}(p, g). Finally, by exploiting causal diamond theory, we show how the distance functional is related (to leading order in the scale L) to spacetime scalar curvature in the causal past of the two lightcones, and briefly illustrate a number of its possible applications.

Degree-based energies of trees

The Coulson-type integral formula for TI energy is established, and two sufficient conditions for TI energy of trees to be minimum are presented.Using the results, for the harmonic energy, the augmented zagreb energy, the geometric-arithmetic energy, and the general sum-connectivity energy (for μ<0) of trees, the minimum energies among trees are determine according to the order and the extremal trees are characterized, respectively.

Noninvasive calibrated tissue temperature estimation using backscattered energy of acoustic harmonics

PurposeA real-time and non-invasive thermometry technique is essential in thermal therapies to monitor and control the treatment. Ultrasound is an attractive thermometry modality due to its relatively high sensitivity to change in temperature and fast data acquisition and processing capabilities. A temperature-sensitive acoustic parameter is required for ultrasound thermometry in order to track the changes in that parameter during the treatment. Currently, the main ultrasound thermometry methods are based on variation in the attenuation coefficient, the change in backscattered energy of the signal (CBE), the backscattered radio-frequency (RF) echo-shift due to change in the speed of sound and thermal expansion of the medium, and change in the amplitudes of the acoustic harmonics. In this work, an ultrasound thermometry method based on second harmonic CBE (CBEh2) and combined fundamental and second harmonic CBE (CBEcomb) is used to produce 2D temperature maps, detect localized heated region generated by low intensity focused ultrasound (LIFU), and control temperature in the heated region. Materials and methodsEx vivo pork muscle tissue samples were exposed to localized LIFU heating source and 2D temperature maps were produced from the RF data acquired by a 4.2 MHz linear array probe using a Verasonics Vantage™ ultrasound scanner (Verasonics Inc., Redmond, WA) after the exposure. Calibrated needle thermocouples were also placed in the ex vivo tissue sample close to the LIFU focal zone for temperature calibration purposes. The estimated temperature maps were the established echo-shift technique. A tissue motion compensation algorithm was also used to reduce the susceptibility to motion artifacts. Results2D temperature maps were generated using CBE of acoustic harmonic and echo-shift techniques. The results show a direct correlation between the CBE of acoustic harmonics and focal tissue temperature for a range of temperatures from 37 °C (baseline) to 47 °C. ConclusionsThe findings of this study show that the CBE of acoustic harmonics technique can be used to noninvasively estimate temperature change in tissue in the hyperthermia temperature range.

High-order harmonic generation of benzene molecules irradiated by circularly polarized laser pulses

High-order harmonic generation is investigated by using time-dependent density functional theory to numerically simulate the interaction of the benzene molecule with a few-cycle circularly polarized laser pulse. Compared with the harmonics from atoms and diatomic molecules with similar ionization energy irradiated by the same laser pulse, the harmonics from benzene molecules possess higher efficiency and cut-off energy. Further research reveals that the harmonic efficiency and cut-off energy of the benzene molecule increase gradually as the wavelength of the driving laser decreases. Through the analysis of the time-dependent evolution of electronic wave packets, it is found that the harmonic generation can be attributed to the recombination of the ionized electrons and their parent ions. By optimizing the driving laser pulse, we demonstrated that high-order harmonic generation in the benzene molecule can be used to produce isolated circularly polarized attosecond pulse.

Effects of free heave motion on wave resonance inside a narrow gap between two boxes under wave actions

Fluid resonance inside a narrow gap between two side-by-side boxes is investigated based on an open-source CFD package, OpenFOAM. An upstream box heaves freely under wave actions and a downstream box remains fixed. The focus of this work is to study the influence of the motion of the upstream box on the hydrodynamic behavior of the resonant fluid inside the gap. The hydrodynamic behavior considered in this study includes the wave height inside the gap, heave displacement and their harmonic components, and reflection, transmission and energy loss coefficients. For comparison, the configuration in which the two boxes are fixed is considered. It was found that the heave motion of the upstream box increases the fluid resonant frequency and significantly reduces the resonant wave height in the gap. The frequencies at which the maximum and minimum heave displacements of the upstream box are observed to obviously deviate from the fluid resonant frequency. For the wave height in the gap and heave displacement, the effects of the incident wave height on their harmonic components are different. The heave motion of the upstream box results in a larger reflection coefficient and smaller energy loss coefficient.

A Developed Sensor for Color Identification, Sorting and Counting Automation Control System

Knowing how to manipulate the data from environment to automation control systems in industry can innovate and improve a quality of the products effectively. In plastic manufacturing, there is a need of automated control system that can recognize color and sort, count and sequentially control processing since the certain quantity of color billets mix into a batch in order to produce desired colorful products. In this paper, a color recognition sensor based on the principle of LEDs energy harvest corresponding actuator has been designed. The derivational voltage due to red, green and blue color shift in color recognition, sorting and counting automation control system is measured as a signal input of the controller that works with the reflected light properties such as the reflective harmonic energy. Sequentially, the automation control system with human machine interface (HMI) and supervisory control and data acquisition (SCADA) will monitor the quantity of diversity color products in intuitive and remote supervisory, customization or adjustments in automation processing. Furthermore, the designed device will integrate into artificial intelligent (AI) and unmanned aerial vehicle (UAV).

A Developed Sensor for Color Identification, Sorting and Counting Automation Control System

Knowing how to manipulate the data from environment to automation control systems in industry can innovate and improve a quality of the products effectively. In plastic manufacturing, there is a need of automated control system that can recognize color and sort, count and sequentially control processing since the certain quantity of color billets mix into a batch in order to produce desired colorful products. In this paper, a color recognition sensor based on the principle of LEDs energy harvest corresponding actuator has been designed. The derivational voltage due to red, green and blue color shift in color recognition, sorting and counting automation control system is measured as a signal input of the controller that works with the reflected light properties such as the reflective harmonic energy. Sequentially, the automation control system with human machine interface (HMI) and supervisory control and data acquisition (SCADA) will monitor the quantity of diversity color products in intuitive and remote supervisory, customization or adjustments in automation processing. Furthermore, the designed device will integrate into artificial intelligent (AI) and unmanned aerial vehicle (UAV).

Shock Absorbers Damping Characteristics by Lightweight Drop Hammer Test for Naval Machines

The technical requirements for naval ships machine foundations are far more strict in comparison to merchant’s vessels. These requirements are confirmed in the military standardization of many countries. Underwater Explosion (UNDEX phenomena) detonation pulses, force naval engineers to design and implement different shock absorbers made from a wide variety of materials. This study presents the tests results of typical shock absorber designs made of various types of rubber and elastomers. The initial objective of the study was to determine the energy absorption of shock impacts, the choice of materials capable of operating within the temperature range of 0 °C to 70 °C, resistance to contact with oils and marine fuel, performance at frequencies ranging from 5 to 30,000 Hz, and absorption no less than 40% of harmonic vibration energy. Initial studies conducted on tensile testing machine were used to determine the static and dynamic stiffness of a shock absorbers. Considerations of stiffness coefficient for the linear and nonlinear range is typical for shock pulses. Further tests were carried out on a lightweight drop hammer to determine the characteristics of the damping coefficient for high-speed wave interactions—Shock Response Spectrum (SRS). The final aim of the study was to assess the repeatability of the shock absorbers response to multiple impact loads. Mechanical properties describing possibilities of tested dampers materials to absorb energy of UNDEX were also presented.

Time-frequency analysis of high harmonic generation using a probe XUV pulse.

Interpretation of strong-field phenomena is mostly based on the analysis of classical electron trajectories in an intense laser field, whose specific properties determine general features of nonlinear laser-matter interaction. Currently, the visualization of closed electron trajectories contributing to high harmonic generation (HHG) of the laser field is the prerogative of a theoretical analysis based on the time-frequency spectrogram of the induced dipole acceleration. Here, we propose a method for direct reconstruction of the HHG time-frequency spectrogram using a time-delayed probe XUV pulse. Our analytical theory and ab initio numerical simulations demonstrate that the XUV-assisted HHG yield as a function of time delay and harmonic energy mimics the short-time Fourier transform of the dipole acceleration induced by the laser field, thereby providing possible in-situ experimental access for tracing electron dynamics in strong-field phenomena.

Dual Resonant Frequency Inductive Power Transfer in an Underwater Tight Coupling System

The application of wireless power transfer technology in the underwater environment proposes both opportunities and challenges to undersea power feeding. Due to the attenuation of electromagnetic waves in seawater, the distance between transmitter and receiver is always maintained at a minimum value, which results in tight coupling between the transmitter and receiver. The tight coupling condition provides a low impedance loop for high-order harmonic, so the component of the harmonic wave is thus significantly increased and cannot be ignored in the power transmission system. In order to fully utilize the harmonic energy, a fundamental-harmonic dual-channel system was proposed and studied in this paper. Compared with single-channel systems transmitting fundamental wave only, the dual-channel system has higher power transmission capability, while the loss in dual channel system can be less than that of a single-channel system after proper optimization. A 3 kW experiment platform is established to verify the effectiveness of theoretical analysis.

Nonadiabatic Molecular Quantum Dynamics with Quantum Computers.

The theoretical investigation of nonadiabatic processes is hampered by the complexity of the coupled electron-nuclear dynamics beyond the Born-Oppenheimer approximation. Classically, the simulation of such reactions is limited by the unfavorable scaling of the computational resources as a function of the system size. While quantum computing exhibits proven quantum advantage for the simulation of real-time dynamics, the study of quantum algorithms for the description of nonadiabatic phenomena is still unexplored. In this Letter, we propose a quantum algorithm for the simulation of fast nonadiabatic chemical processes together with an initialization scheme for quantum hardware calculations. In particular, we introduce a first-quantization method for the time evolution of a wave packet on two coupled harmonic potential energy surfaces (Marcus model). In our approach, the computational resources scale polynomially in the system dimensions, opening up new avenues for the study of photophysical processes that are classically intractable.

Quality testing of spectrum-based valency descriptors for polycyclic aromatic hydrocarbons with applications

In this paper, we investigate the prediction potential of commonly occurring eigenvalues-based descriptors which are related to chemical matrices corresponding to valency of vertices. The normal boiling point has been chosen to be representative of van-der-Waals and intermolecular type interactions, whereas, the standard enthalpy/heat of formation is selected to represent thermal properties, for our comparative testing. First, we propose a unified computational method to calculate commonly occurring eigenvalues-based valency descriptors. Experimental results show that our proposed method possesses less algorithmic and computational complexities and is more computationally diverse. The proposed method is used to calculate commonly occurring eigenvalues-based descriptors to investigate their correlation ability with the experimental data for the two chosen physicochemical properties. The Randić energy shows the best correlation among all the commonly occurring eigenvalues-based descriptors. Experimental results show some unexpected outcomes as the correlation ability of the well-known adjacency energy and the Laplacian & signless Laplacian Estrada indices is weak. Unlike their reputation among researchers, the harmonic energy and Estrada index outperformed all the well-known eigenvalues-based descriptors. The results warrant further usage of the harmonic energy and Estrada index in the structure-activity and structure-property models. Our study contributes towards putting forward the best spectrum-based topological descriptors while mentioning the ones which do not deserve further attention of researchers. Applications to certain families of titania nanotubes are presented.

Correlation between total harmonic distortion of load and error percentage of kwh meter on inverter

This study aims to describe the correlation between total harmonic distortion (current) of load and error percentage of kWh meter to overcome the electric circuit that supplied from inverter through digital kWh meter. The method used in this research was an experimental method with a design set that consists of an inverter connected to incandescent lamp as linear load through power qualty analyzer and digital kWh meter. Next, researcher observed and recorded the total harmonic distortion (current) and energy on the power quality analyzer that connected to the loads circuit for 1 hour. Then compared the energy measurement results with a digital kWh meter, calculated, and analyzed it as an error to be concluded the correlation between total harmonic distortion (current) of load and error percentage of digital kWh meter on the inverter. The load that presented by incandescent lamp affect to measurement of kWh meter. The energy that be consumed of load of 100 watt during 60 minutes is 102.99 Wh. Based on the measurement data, the average error percentage of kWh meter is 2.52% for linear load that caused by 2.85% of total harmonic distortion (current). The higher the total harmonic distortion (current), the higher the error percentage of kWh meter on the inverter that occurs is. And the equation of the correlation between total harmonic distortion (current) of load and percentage of error in kWh meter in inverter gives the R2 of 0,9236 that means the independent factors are not significant.

Research on the Topology of Wireless V2G for Electric Vehicle

Based on the circuit topology for the electric vehicle wireless V2G power transmission system, the boost circuit, wireless resonance circuit and grid-connected inverter circuit of the system were studied. According to the characteristics of the boost converter, a voltage feedback closed-loop control model based on PID and PWM was established. Since the excitation and magnetic leakage of the wireless transmission coil could not be ignored, the maximum transmission power model of the wireless resonance circuit was derived. Starting from the operation mode of the three-phase grid-connected inverter circuit, the control rules of the three-phase bridge arm that sent electrical energy back to the grid in a steady state were obtained. The simulation results showed that the maximum transmission power of the electric vehicle wireless V2G power transmission system was affected by the leakage magnetic field of the wireless transmission coil, and the maximum transmission power was inversely proportional to the leakage magnetic field. In addition, the boost circuit and grid-connected inverter circuit in the system were sources of harmonics, and a large amount of harmonic energy was sent to the grid during the operation process of the electric vehicle wireless V2G circuit.

Impact of Antiphase Boundaries on Structural, Magnetic and Vibrational Properties of Fe3Al.

We performed a quantum-mechanical study of the effect of antiphase boundaries (APBs) on structural, magnetic and vibrational properties of FeAl compound. The studied APBs have the {001} crystallographic orientation of their sharp interfaces and they are characterized by a 1/2〈111〉 shift of atomic planes. There are two types of APB interfaces formed by either two adjacent planes of Fe atoms or by two adjacent planes containing both Fe and Al atoms. The averaged APB interface energy is found to be 80 mJ/m and we estimate the APB interface energy of each of the two types of interfaces to be within the range of 40–120 mJ/m. The studied APBs affect local magnetic moments of Fe atoms near the defects, increasing magnetic moments of Fe atoms by as much as 11.8% and reducing those of Fe atoms by up to 4%. When comparing phonons in the FeAl with and without APBs within the harmonic approximation, we find a very strong influence of APBs. In particular, we have found a significant reduction of gap in frequencies that separates phonon modes below 7.9 THz and above 9.2 THz in the defect-free FeAl. All the APBs-induced changes result in a higher free energy, lower entropy and partly also a lower harmonic phonon energy in FeAl with APBs when compared with those in the defect-free bulk FeAl.

A new algorithm for calculating utility harmonic impedance

In engineering, it is very valuable to estimate the utility harmonic impedance of a point of common coupling (PCC). However, the existing methods usually assume that the customer harmonic impedance is much larger than the utility harmonic impedance, if not, the estimated accuracy is hard to meet engineering requirement. Unfortunately, in modern power grid, due to the influence of filters or reactive compensation capacitors installed on the customer side of a PCC, the above assumption is no longer valid. This paper proposes a new algorithm to overcome this problem, the proposed algorithm can get a fairly good estimated result while the amplitude of utility harmonic impedance is approximately equal to the customer harmonic impedance. In this algorithm, firstly, the amplitude of utility harmonic impedance is calculated by using the weak correlation of the fluctuation of the harmonic sources on both sides of a PCC, and the impedance angle can be obtained through minimizing background harmonic fluctuation energy. Simulation and field case verify the effectiveness.

A Novel Indicator to Improve Fast Kurtogram for the Health Monitoring of Rolling Bearing

Envelope demodulation based on vibration data is widely used for the fault detection of rolling element bearing, which yet largely relies on the high signal to noise ratio of signal. In practical scenarios, because of the existence of various interfering components, it is necessary to estimate the fault-sensitive frequency band for feature enhancement. However, many of current approaches are likely to produce misleading results for that they are robust only for part of these interferences. Facing with this problem, an alternative method, named as ALKurtogram, is proposed by aligning the frequency division strategy of traditional fast kurtogram (FK) with a new indicator, the averaged local kurtosis (ALK). ALK measures both the local and overall impulsiveness of objective component, which intrinsically makes up for some drawbacks of previous methods under multi-interference condition for fault feature extraction. The inherent nature of ALK also allows it to be compatible with the time-varying speed, hence more widespread industrial applications can be achieved. Furthermore, a harmonic energy index (HEI) is defined by following the result of ALKurtogram to ascertain the order of principle component for bearing status recognition. The effectiveness and superiority of proposed method are validated experimentally by comparing with FK, the results prove that it is a powerful tool for reliable monitoring of bearing.

Generation of the high-intensity single harmonic energy peak and attosecond pulse by using resonance ionization schemes from atoms and molecules

The lower harmonic intensity is still the reason that limits the application of attosecond pulse. Thus, in this paper, on the basis of resonance ionization schemes, we propose the effective methods to improve the harmonic intensity of atomic and molecular systems. For atomic system (i.e. He atom), with the combination of chirped-UV pulse, not only the harmonic cutoff can be extended, but also the harmonic intensity can be enhanced, caused by the UV resonance ionization between ground state and excited state. As a result, the single harmonic energy peak (HEP) with the higher intensity and higher emitted photon energy can be obtained, which can support the attosecond pulses shorter than 40 as. For the molecular system (i.e. [Formula: see text] and [Formula: see text]), by properly choosing the pulse duration of the fundamental pulse, the time region of charge resonance enhanced ionization (CREI) can be well controlled. Therefore, the maximum HEP with the higher intensity can be obtained. Second, by properly adding a half-cycle unipolar pulse, the selected maximum HEP in the CREI region can be further extended. Thus, an intense and broad spectral region can be produced, which can generate the attosecond pulses with durations of 36[Formula: see text]as.

Temperature Wave Fatigue Damage and Dissipated Energy Approach to Flow Number Estimation of Asphalt Concrete

Abstract The effect of sinusoidal temperature on the fatigue life of asphalt concrete (AC) under continuous loading was investigated. The traditional failure criteria of 50 % loss in stiffness, stiffness ratio, and dissipated energy ratio were employed to analyze the AC fatigue test results. Dissipated energy approach and dissipated energy ratio were also extended to estimate the flow number (FN) of AC. The varying temperature induces a continuously changing temperature gradient across the AC beam. This, in turn, triggers the formation of continuously alternating weaker and harder outer layer relative to the beam core, thus creating a stiffness undulation. The combined effect of the load and temperature cycles resulted in a stiffness diminishing trend similar to that of damped harmonic vibration energy. The bottom of the beam is subjected to additional tensile strain/stress for a negative temperature gradient, while the top of the AC beam is subjected to additional compressive strain/stress for a positive temperature gradient. The temperature amplitude and period have a significant influence on the diminishing trend of the stiffness. Results from all the fatigue life estimation and prediction methods employed showed that the fatigue life of AC under variable temperature is shorter than that under constant temperature. However, the effect of the variable temperature is felt much more at lower strain loading. Nonrecovered strain energy method was successfully employed to estimate the AC FN.

Efficient harmonic oscillator chain energy harvester driven by colored noise

We study the performance of an electromechanical harmonic oscillator chain as an energy harvester to extract power from finite-bandwidth ambient random vibrations, which are modelled by colored noise. The proposed device is numerically simulated and its performance assessed by means of the net electrical power generated and its efficiency in converting the external noise-supplied power into electrical power. Our main result is a much enhanced performance, both in the net electrical power delivered and in efficiency, of the harmonic chain with respect to the popular single oscillator resonator. Our numerical findings are explained by means of an analytical approximation, in excellent agreement with numerics.