Input Power Research Articles

Assessment of using different ozone-friendly R22 alternative refrigerants in residential air conditioners in a high-ambient temperature country

The performance of a vapor compression refrigeration system (VCRS)-based residential air conditioner operating in a high-ambient temperature (HAT) country was investigated using six zero-ODP (ozone depletion potential) refrigerants as replacements to R22. The non-flammable alternative refrigerants considered in the present research were R134a, R404A, R407C, R410A, R448A, and R507A. Using the basic conservation laws, the VCRS was modeled during steady-state operation and solved using engineering equation solver (EES) software. Coefficient of performance (COP), pressures and temperatures at compressor suction and discharge, Global Warming Potential (GWP), critical pressure and temperature, compressor pressure ratio, volumetric cooling capacity (VCC) specific cooling capacity (SCC), and refrigeration effect were utilized as assessment criteria for the alternative refrigerants considered. From these refrigerants, the highest values of suction pressure, discharge temperature, and condenser pressure were attained by R410A. In addition, the discharge temperatures for all refrigerants, except R134a, were all higher than their corresponding critical values, causing a quicker drop in the VCRS’s performance. As an alternative refrigerant, R407C showed the highest SCC of 141.0 kJ/kg followed directly by 139.2 and 138.0 kJ/kg for R410A and R448A, respectively. A reverse trend was found for VCC with respective values of 4722 and 3775 kJ/m3 for R410A and R448A. Lower volume flow rates and smaller-sized compressors are expected for higher VCC refrigerants. The same trend was found for the compressor’s specific work input and condenser’s specific heat transfer with values of (51.14, 46.82, and 45.38 kJ/kg) and (190.3, 187.8, and 183.4 kJ/kg) for R410A, R407C, and R448A, respectively. For applications in HAT countries, larger condenser’s specific heat transfer makes the refrigerant more applicable. Conversely, with respect to COP, refrigerant R134a with a value of 3.075 was the superior alternative followed by R448A and R407C with respective COPs of 3.042 and 3.011. Based on the overall assessment in terms of environmental obligation, COP, compressor input power, refrigerant flow rate required, and all the evaluations made in this research, refrigerant R448A was recommended as the most appropriate substitute to R22 which can effectively be used in residential air conditioners in a HAT country.

Thermal defocus-free Hartmann Wavefront Sensors for monitoring aberrations in Advanced Virgo

Earth-based gravitational waves interferometric detectors are shot-noise limited in the high-frequency region of their sensitivity band. While enhancing the laser input power is the natural solution to improve on the shot noise limit, higher power also increases the optical aberration budget due to the laser absorption in the highly reflective coatings of mirrors, resulting in a drop of the sensitivity of the detector. Advanced Virgo exploits Hartmann Wavefront Sensors (HWSs) to locally measure the absorption-induced optical aberrations by monitoring the optical path length change in the core optics. Despite the very high sensitivity of Hartmann sensors, temperature fluctuations can cause a spurious curvature term to appear in the reconstructed wavefront due to the thermal expansion of the Hartmann plate, that could affect the accuracy of the aberration monitoring. We present the implementation and validation of a control loop to stabilize the Advanced Virgo HWS temperature at the order of ΔT⩽0.01 K, keeping the spurious curvature within the detector’s requirements on wavefront sensing accuracy.

Design and fabrication of a heat pipe and thermoelectric cooler-based food delivery box for vehicles

In recent years, there has been a notable surge in interest regarding the application of heat pipe and thermoelectric cooling technologies to recuperate waste heat, conserve energy, and augment thermal efficiency across diverse commercial and engineering domains. Particularly within the realm of food delivery services reliant on online ordering systems for the conveyance of freshly prepared meals from restaurants to consumers, sustaining the quality of food during transit poses a significant challenge due to heat dissipation from food containers over extended transportation distances. Consequently, maintaining optimal food temperature or beverage warmth in online orders becomes a pressing concern. This investigation's primary goal was to design and construct a portable heating-cooling chamber that would maintain food temperature during transportation. This technological endeavor offers a viable solution to contemporary energy dilemmas by leveraging electricity and waste energy from vehicles to furnish efficient cooling and heating mechanisms. The heating aspect of the chamber is facilitated by a meticulously developed heat pipe system that utilizes deionized water as the working fluid. Experimental results reveal that a 75 % filling ratio engenders optimal heat pipe performance across varying input power levels. The proposed design amalgamates a heating and cooling chamber, integrates a thermosyphon heat pipe within the exhaust gas trajectory to recuperate dissipated heat, and harnesses the vehicle battery to power a thermoelectric cooler. Experimental results substantiate the efficacy of the thermosyphon heat pipe in elevating the heating chamber's temperature to 48 °C within a span of 25 min, while concurrently, the thermoelectric cooler achieves the desired cooling chamber temperature of 5 °C within a mere 8 min.

A petavoxel fragment of human cerebral cortex reconstructed at nanoscale resolution.

To fully understand how the human brain works, knowledge of its structure at high resolution is needed. Presented here is a computationally intensive reconstruction of the ultrastructure of a cubic millimeter of human temporal cortex that was surgically removed to gain access to an underlying epileptic focus. It contains about 57,000 cells, about 230 millimeters of blood vessels, and about 150 million synapses and comprises 1.4 petabytes. Our analysis showed that glia outnumber neurons 2:1, oligodendrocytes were the most common cell, deep layer excitatory neurons could be classified on the basis of dendritic orientation, and among thousands of weak connections to each neuron, there exist rare powerful axonal inputs of up to 50 synapses. Further studies using this resource may bring valuable insights into the mysteries of the human brain.

Engineering design and manufacturing of a radio frequency plasma driver without Faraday shield for NBI application

A radio frequency (RF) driven ion source is favorable for high-power and long-pulse neutral beam injection (NBI) system. To reduce the damage caused by the isotropic heat and particle fluxes from the plasma, the traditional RF plasma driver of the NBI ion source introduces a Faraday shield (FS) for protection. However, the simulations and experiments show that the FS seriously affects the RF coupling and around 50 % of the input power deposits on the FS. The water-cooled discharge tubes with a double-layer ceramic structure have been developed to avoid using the FS structure. It's expected to improve the RF power transfer efficiency and to promote the development of high-power and long-pulse RF ion source. To verify the feasibility of the double-layer ceramic structure, the paper has carried out the fluid-thermal-structural coupling analysis and the fracture mechanical analysis on two proposed types: the alumina ceramic brazing structure and the silicon nitride ceramic bonding structure. The sample tests and the prototype manufacturing have been completed. Preliminary tests of the plasma discharge on the prototype of the alumina ceramic brazing structure have been launched. A plasma discharge of 30 kW and 20 s have been achieved.

A self-powered magnetoelectric 3D tactile sensor with adjustable sensitivity for robot arms

With the rapid development of robot arms in various industries, the interactions between the tip ends of robot arms and the target surfaces or objects play an important role. Tactile sensors, particularly for force measurement, are widely used at the tip ends of robot arms for information exchange. Currently, most of the tactile sensors used at the tip ends of robot arms are with one planar or arc sensing surface (2D sensing area), which can only measure the contact force when the surfaces or objects are facing the sensing surface (around 180° working space range). However, contact forces may come from any direction (360° working space range), which needs tactile sensors with 3D sensing area to measure multi-direction contact forces. To tackle this problem, a self-powered magnetoelectric 3D tactile sensor (SM3D-TS) is proposed in this paper. Firstly, the design and fabrication of the SM3D-TS are described in detail. Secondly, the mechanical properties of the SM3D-TS are tested. Thirdly, the voltage-force relationship of the SM3D-TS is calibrated in single direction. Then, the force measuring and random points positioning performances are validated. Without power input, the SM3D-TS can measure contact forces from multiple directions with speed-dependent sensitivity. The experimental results show that the SM3D-TS can not only accurately measure the contact forces at given speed by independently using the induced voltages in the three axes, but also can position random points at given contact speed with high accuracy.

Development of 2400-2450 MHz Frequency Band RF Energy Harvesting System for Low-Power Device Operation.

Recently, there has been an increasing fascination for employing radio frequency (RF) energy harvesting techniques to energize various low-power devices by harnessing the ambient RF energy in the surroundings. This work outlines a novel advancement in RF energy harvesting (RFEH) technology, intending to power portable gadgets with minimal operating power demands. A high-gain receiver microstrip patch antenna was designed and tested to capture ambient RF residue, operating at 2450 MHz. Similarly, a two-stage Dickson voltage booster was developed and employed with the RFEH to transform the received RF signals into useful DC voltage signals. Additionally, an LC series circuit was utilized to ensure impedance matching between the antenna and rectifier, facilitating the extraction of maximum power from the developed prototype. The findings indicate that the developed rectifier attained a peak power conversion efficiency (PCE) of 64% when operating at an input power level of 0 dBm. During experimentation, the voltage booster demonstrated its capability to rectify a minimum input AC signal of only 50 mV, yielding a corresponding 180 mV output DC signal. Moreover, the maximum power of 4.60 µW was achieved when subjected to an input AC signal of 1500 mV with a load resistance of 470 kΩ. Finally, the devised RFEH was also tested in an open environment, receiving signals from Wi-Fi modems positioned at varying distances for evaluation.

Simplified modeling of scroll compressors with vapor injection

Semi-empirical models for predicting the suction flow rate, injection flow rate, input power consumption, and discharge temperature are proposed for scroll compressors with vapor injection. A data set containing four compressors wherein each compressor was tested over a range of operating conditions is used to evaluate the models. The fitted parameters of the models and the prediction errors of each data set are discussed. The accuracy and generalizability of applying the models to the same compressor with and without vapor injection are also discussed.

Empirical Investigation of a Single-phase Input Switched AC-DC Boost Converter with Improved Power Quality

The Boost converter topology is most widely used for power factor correction (PFC) converters. The conventional passive Boost PFC converter inherently suffers from the lack of controllability and non-ideal characteristics of the diode-bridge rectifier. Replacing diodes with active switch(es) offers viable solutions but increases the circuit complexity. Addressing this trade-off, a novel design of a single–phase input switched AC to DC Boost converter has been presented in this article. The active switch of the Boost DC converter is shifted to the input side of the full-bridge diode rectifier which provides more control on the input current without increasing much of the circuit complexity. Two Boost inductors and two output split capacitors are used for providing higher step-up operation compared to the conventional. The converter has been simulated both in open-loop and closed-loop conditions using the PSIM software. The simulation results show that the proposed converter provides good dynamic response and can maintain a constant stable output voltage during sudden load change. Furthermore, to evaluate the experimental performance of the suggested converter, a prototype converter has been developed. A scaled-down experiment has been performed which shows that the converter can achieve up to 85.2 % efficiency and an input power factor of 0.9.

Design and Fabrication of a Film Bulk Acoustic Wave Filter for 3.0 GHz-3.2 GHz S-Band.

Film bulk acoustic-wave resonators (FBARs) are widely utilized in the field of radio frequency (RF) filters due to their excellent performance, such as high operation frequency and high quality. In this paper, we present the design, fabrication, and characterization of an FBAR filter for the 3.0 GHz-3.2 GHz S-band. Using a scandium-doped aluminum nitride (Sc0.2Al0.8N) film, the filter is designed through a combined acoustic-electromagnetic simulation method, and the FBAR and filter are fabricated using an eight-step lithographic process. The measured FBAR presents an effective electromechanical coupling coefficient (keff2) value up to 13.3%, and the measured filter demonstrates a -3 dB bandwidth of 115 MHz (from 3.013 GHz to 3.128 GHz), a low insertion loss of -2.4 dB, and good out-of-band rejection of -30 dB. The measured 1 dB compression point of the fabricated filter is 30.5 dBm, and the first series resonator burns out first as the input power increases. This work paves the way for research on high-power RF filters in mobile communication.

Computational study of a helium-propellant microwave electrothermal thruster

The microwave electrothermal thruster (MET) utilizes wave-exited microdischarges to heat gas flows, enhancing the specific impulse of the thruster. Our computational study investigates a 17.5 GHz helium-propellant MET, employing a two-dimensional, axisymmetric fluid model of plasma coupled with electromagnetic wave and gas flows. The discharges operate in the glow regime, remaining weakly ionized, and in thermal non-equilibrium. The plasma densities reach approximately 1020m−3, and the gas temperature is around 2000 K. Even a slight off-resonant frequency operation results in a significantly lower plasma density and gas temperature. Gas heating, primarily driven by electromagnetic Joule heating, plays a critical role in influencing the overall discharge behavior. The measured peak thrust and specific impulse are 8.24 mN and 292 s, respectively, at a mass flow rate of 3.2 mg/s with 30 W of power. Compared to a cold gas thruster, there is a significant increase in the specific impulse by a factor of approximately 1.7. The enhanced performance trades off with propulsive efficiency, which decreases by a factor of 1.5 from the peak 65% at 10 W. This is due to higher energy losses to cavity walls from heat conduction with increased power. These findings underscore the critical balance between the input power and mass flow rate to improve the MET performance, highlighting the importance of power management to maximize thrust and efficiency. Furthermore, the predicted thrust and specific impulse agree well with experimental values for nominally similar MET thruster studies in the literature.

Design and optimization of a miniaturized dual band rectenna for wireless power transfer applications

This paper presents the design of a compact printed rectenna circuit suitable for wireless power transfer applications at frequencies 900 MHz and 1450 MHz. The rectenna circuit consists of a rectangular patch antenna measuring 17.7 x 8.85 mm2, printed on a Rogers RO4003 substrate. It also includes a voltage doubler (VD) circuit comprising Schottky diodes (SMS7631) and an impedance-matching circuit. The design and optimization of the antenna are performed using Ansys HFSS software, while the DC and RF features of the VD circuit are analyzed using the Advanced Design System (ADS) software. The circuit design is presented in two stages: one for single-frequency operation at 900 MHz and another for dual-band operation at 900 and 1450 MHz. The design of single-stage and double-stage VD for dual-band operation is also discussed in this paper. The rectenna's Power Conversion Efficiency (PCE) is evaluated under various load and input power conditions. The maximum DC output voltage measured is 5.318 V at 900 MHz and 5.52 V at 1450 MHz. Furthermore, the maximum PCE achieved is 53% and 54% for 900 MHz and 1450 MHz respectively. These values are obtained with a RF input power level of 20 dBm and a load resistance of 10 KΩ.

Modulation instability in nonidentical metamaterial waveguide arrays by graph Laplacian approach

We theoretically investigate modulation instability (MI) in a nonidentical waveguide array, which is made up of positive and negative index metamaterial waveguides. The unit cell of the optical waveguide array consists of three waveguides arranged in a triangular manner. Waveguides 1 and 3 are made up of positive index material (PIM) channels and waveguide 2 is by negative index material (NIM) channels, as a result, they show different light propagation characteristics. We model this array of waveguides using a generalized nonlinear Schro¨dinger equation, replacing the Laplacian operator with the graph Laplacian. Following linear stability analysis, we will discuss MI for different values of transverse wave number, as it determines the order of the Brillouin zone. We also discuss the effect of input power on periodic MI in normal and anomalous dispersion regimes. Thus we report a comprehensive study on the MI and hence the better ways to generate and manipulate the solitons or ultra-short pulses in NIM PIM waveguide arrays.

128-channel optical phased array with large field of view and low main-lobe attenuation

In this paper, a 128-channel non-uniform optical phased array is proposed. The antenna is based on a silicon nitride waveguide with a large cross-sectional area (3 μm × 1.2 μm) and a silicon nitride grating with a small diffraction window (grating width of 200 nm), enabling high optical power transmission and a wide 1 dB field of view. As a result, the designed sparse optical phased array achieves less than 1 dB of main lobe attenuation over a 94° field of view. Within this field of view, the main lobe will not fall below 80% of the maximum main lobe. This allows the minimum detection distance to still be about 89% of the maximum detection distance without increasing the input power. In this field of view, the maximum side-lobe suppression of the designed sparse optical phased array is 13.4 dB, and the minimum side-lobe suppression is higher than 11.9 dB. This is useful for simultaneously achieving a large field of view, low main lobe attenuation, stable side-lobe suppression, and long detection distance.

Analysis, Design and Effectuation of a Tapped Inductor Current Converter with Fractional Output for Current Source Systems

This article proposes a new connection method of tapped inductors that works in the current source, which enables the current-mode power converter circuit to have a new topological relationship. Usually, in a switched-inductor circuit, a stable output multiple is obtained through the connection of the inductor and the switching devices. This is because the tapped point on the inductor varies, and the magnetomotive force (mmf) of inductance is adjusted. Thereby, the output current is controlled by the states of switching devices within a certain range. This optimized circuit structure can adjust the output current according to load changes in practical applications without changing the input power supply. The proposed method has been verified for its feasibility through detailed analysis and hardware work. The principal analysis based on the flux linkage and the PSIM simulation confirms that the theoretical circuit can be implemented. Finally, a hardware circuit is built to obtain real and feasible conclusions, and it is verified that the circuit can achieve a stable output and variable current within a specific range. The proposed work presents an alternative power conversion methodology using the active switching of mmf, and it is a stable and simple power conversion technique.

Numerical Investigation of Process Parameter Effects on Flow Oscillations in a Natural Circulation Boiling Integral PWR-Type SMR Test Rig

Innovative reactor designs like small modular reactors (SMRs) have the potential to operate in a natural circulation (NC) boiling mode, but this mode introduces flow oscillations that pose a risk to nuclear safety. Therefore, it is essential to investigate the effects of various parameters on these oscillations. This study focuses on predicting the operational behavior of the Integral PWR-type SMR Test Rig (iPSTR) when operating in NC and subcooled boiling conditions. The iPSTR replicates an NC boiling loop with a vertical heater, vertical cooler configuration, high-temperature and high-pressure conditions, and nonuniform diameter structure. Using the RELAP5 model, thermal-hydraulic simulations were performed to anticipate how varying degrees of inlet subcooling affects parameters such as mass flow rate and void fraction, with experimental data used to validate the model’s accuracy. This investigation covers a range of process conditions, including system pressures from 5 to 20 bars, core input power varying from 8.5 to 14.5 kW, and degrees of inlet subcooling from 1 to 49 K. The results reveal that increasing input power leads to higher average mass flow rates, while at a constant system pressure, higher input power stabilizes flow rates at higher degrees of inlet subcooling. Moreover, reduced and more consistent oscillation amplitudes and frequencies at higher core power result at more elevated system pressure, enhancing the safety of the iPSTR facility.

Deep learning-based prediction of thermal residual stress and melt pool characteristics in laser-irradiated carbon steel

Residual stress is a crucial factor that must be managed in laser manufacturing processes. Neglecting it can result in product failure or unsuitability for the intended use. In this article, we present the first surrogate deep learning model based on generative adversarial network that predicts thermal residual stress and melt pool characteristics on the cross-section of laser-irradiated carbon steel. The model was trained using simulation data obtained from the unified momentum equation approach-based numerical model. Our model was designed to predict various aspects of the laser melting process only from three scalar inputs of laser power, beam diameter, and irradiation time at two different points in time (immediately after the laser heating is finished and when the steel is completely cooled down) and successfully predicted the distributions of 12 variables, including residual stress and temperature. Prediction results were not only qualitatively very similar to their ground truth, but also quantitatively accurate with the R2 values ranging from 0.975 to 0.999 and the mean absolute errors between 0.0015 and 0.0126. We demonstrated that complex experiments can be quickly performed using the surrogate model because a single deep learning prediction took only 0.13 s, compared to the 2.5–8 h numerical simulation times.

Electro-optomechanical entanglement in two coupled optical cavities with an LC microwave circuit

We theoretically investigate entanglement in a hybrid quantum system comprising two optical cavities coupled to a shared microwave cavity via optomechanical interactions. Our results demonstrate that increasing the microwave input power and frequency in the allowed range enhances entanglement between the microwave–optical and optical–optical modes. We also show by change frequency of the one optical cavity in the communication domain that we still have entanglement. This ability to generate robust microwave–optical photon entanglement shows promise for various quantum technologies. Optical photons could enable secure quantum communication in optical fibers, while microwave photons allow transmission to satellites. Overall, this hybrid cavity optomechanical system offers prospects as an efficient source of entangled photon pairs, vital for implementing long-distance quantum communication networks.

The study of input power of an underwater free-damping ribbed plate in statistical energy analysis

To study the vibration characteristics of the free-damping ribbed plate with fluid load under point force excitation in statistical energy analysis (SEA), the theoretical model of input power calculation was established in this research. The simulational results from SEA commercial software validated the correctness of the proposed theoretical model. As inferred from the theoretical model, the added damping layer and ribs significantly affect the effective bending stiffness and area density, and the added fluid load only affects the effective area density. These effective parameters will affect the input power of the fluid-loaded free-damping ribbed plate, resulting in increased input power as a function frequency. The research in this paper could provide theoretical guidance on the vibroacoustic analysis of underwater complex ship structures.

The High Beam to Power Efficiency Investigation of Miniaturized Microwave Ion Source

A miniaturized 2.45 GHz microwave ion source (MIS) with plasma chamber of ϕ30 mm × 40 mm that has the ability to produce more than 20 mA CW hydrogen ion beam with 180 W microwave power has been built at Peking University (PKU) 5 years ago1. A hibrid discharge principle has been proposed on this kind of MIS2. Recently, under the structure of this MIS, factors such as input power, pressure, magnetic field configuration and the size of plasma chamber have been investigated. Based on this research, a more compact 2.45 GHz microwave ion source with inner diameter of 24 mm has been developed. A 32.5 mA hydrogen ion beam was obtained with only 100 W microwave power.