Low Power Conditions Research Articles

Implementation of High-Efficiency and Ultra-Low-Power Transceiver for the Design of Body Channel Communication Applications

Body channel communications (BCCs) were investigated, to enhance requirements for low power and high-reconfiguration power within permitting technology of wireless measurement systems for wireless communication applications. Standard options for BCC are targeted totally toward channel modeling with a potency measuring technique, a transmission technique, and a wireless transceiver style. Wireless digital transmission designed as a personalized methodology meant for the body channel offers significantly the necessary pathway to implement versatile and low-power BCC systems. In addition to the developing level of wearable communication protocol and applications, there is also an increasing reliability on a flexible BCC transmitter which helps to reconfigure power and meet power reduction conditions. This paper proposes an ultra-low-power, Hamming encoding-based, and body channel communication receiver for wireless body area network applications. Proposed BCC transmitter uses a channel of 1–100 MHz frequency to enhance the transmitter frequency and time domain properties. Hamming-based BCC transmitter makes use of a two-stage low-power analog processing circuit and digital information restoration circuit. Analog processing circuit consists of a dual op-amp adjustable preamplifier. Proposed BCC transceiver has higher data reliability because of the orthogonal characteristic of the Hamming codes. Moreover, the proposed Hamming code concatenated method strengthens the jitter tolerance and improves the code rate. Proposed BCC transceiver was verified using a field-programmable gate array board. Proposed data transceiver achieves a data speed rate of 20 Mbps. Bit error reduction values achieved were < 10−6 and < 10−5 at 60 Mbps and 100 Mbps, respectively. It uses a primary space of 0.14 mm × 0.2 mm when it is functioning below a 15 Mb/s data rate (low-power) condition. BCC transmitter utilizes the power of only 1.0 mW.

Photoelectrical reading in ZnO/Si NCs/p-Si resistive switching devices

The increasing need for efficient memories with integrated functionalities in a single device has led the electronics community to investigate and develop different materials for resistive switching (RS) applications. Among these materials, the well-known Si nanocrystals (NCs) have demonstrated to exhibit RS properties, which add to the wealth of phenomena that have been studied on this model material platform. In this work, we present ZnO/Si NCs/p-Si resistive switching devices whose resistance state can be electrically read at 0 V under the application of low-power monochromatic illumination. The presented effect is studied in terms of the inner structural processes and electronic physics of the device. In particular, the creation of conductive filaments through the Si NC multilayers induces a low-resistance path for photogenerated carriers to get extracted from the device, whereas in the pristine state charge extraction is strongly quenched due to the insulating nature of the NC-embedding SiO2 matrix. In addition, spectral inspection of the generated photocurrent allowed unveiling the role of Si NCs in the reported effect. Overall, the hereby shown results pave the way to obtain memories whose RS state can be read under low-power conditions.

Study of seed plasma generation for NBI plasma start-up using non-resonant microwave launch in Heliotron J

Here, we report on a study of seed plasmas produced by non-resonant 2.45 GHz microwave heating in Heliotron J, which is useful for plasma start-up by neutral beam injection (NBI) under the conditions of low beam power (<1 MW), low accerelation voltage (<30 kV) and small device size (∼1 m). The pre-ionization technique using the non-resonant heating produced the electron density in the order of 1017–1018 m−3 with the energy exceeds the CII ionization potential (30 eV). The existence of the relativistic electrons, which was essential to produce the seed plasmas, was confirmed experimentally during the pre-ionization phase by the synchrotron radiation and the hard x-ray emission measurements. The production mechanism of the relativistic electrons was considered to be stochastic interactions between the electrons and the microwave-frequency field. By optimizing the additional gas fueling during the microwave launch, a higher seed-plasma density more than 4 × 1018 m−3 was obtained, resulting that a rapid density evolution after NBI turn-on was successful even in the low NBI power (0.3 MW) condition. The seed plasmas produced by the pre-ionization method is useful to realize the plasma start-up under low absorption power condition in larger heliotron/stellarator devices such as perpendicular NBI in W7-X or deuterium NBI in LHD.

Application of multiple linear regression to trip setpoint analysis in a reactivity‐initiated accident of a molten salt reactor

The trip setpoint parameters of a molten salt reactor have been analyzed by performing multiple linear regression (MLR) method. In the analysis, a reactivity-initiated accident with inadvertent control rod withdrawal accident under low power condition was considered as the initiating event. A total of 285 cases located from 20 235 thermal-hydraulic simulation runs have been divided into identification dataset (70%) and test dataset (30%) for MLR. MLR models show that the maximum fuel salt temperature and corresponding control rod extraction rate follow a quite convincing linear hypotheses relationship with trip setpoint parameters. Sensitivity analysis gives the sensitivity rankings of trip setpoint parameters. And the predictive values of three significantly influential trip setpoint parameters with different margin considerations have been acquired quantitatively.

Experimental dynamic dispatch of a 60 kW proton exchange membrane electrolyzer in power-to-gas application

A 60 kW PEM electrolyzer was modified to have dynamic dispatch capabilities through the use of an external mass flow controller and was subsequently operated and studied in detail as a part of the UC Irvine power-to-gas (P2G) demonstration project. The system operated in load following for both rooftop solar PV output and aggregated wind farm power. The electrolyzer system was able to handle 100% up and down ramps of the electrolyzer stack in sub-second intervals during variable renewable energy load following experiments. Overall system efficiency was improved by imposing a minimum load condition to avoid high parasitic losses at low power conditions, and cycling the system off/on as required and enabled by quick cold start-up capability. Performance was characterized for varying levels of part load and dynamic operation. The gas drying process was found to be a significant source of loss at low power conditions.

Laser Modulation of Superconductivity in a Cryogenic Wide-field Nitrogen-Vacancy Microscope.

We realize a cryogenic wide-field nitrogen-vacancy microscope and use it to image Abrikosov vortices and transport currents in a superconducting Nb film. We observe the disappearance of vortices upon increase of laser power and their clustering about hot spots upon decrease, indicating local quenching of superconductivity by the laser. Resistance measurements confirm the presence of large temperature gradients across the film. We then investigate the effect of such gradients on transport currents where the current path is seen to correlate with the temperature profile even in the fully superconducting phase. In addition to highlighting the role of temperature inhomogeneities in superconductivity phenomena, this work establishes that under sufficiently low laser power conditions wide-field nitrogen-vacancy microscopy enables imaging over mesoscopic scales down to 4 K with submicrometer spatial resolution, providing a new platform for spatially resolved investigations of a range of systems from topological insulators to van der Waals ferromagnets.

Should I Stay or Should I Go? Founder Power and Exit via Initial Public Offering

Founders can voluntarily exit their ventures via initial public offerings (IPOs). This study builds on power theory to develop and test a model of founder exit using a dataset of 313 founders from 177 entrepreneurial IPOs between 2002 and 2010. We largely find support for the model—a negative relationship between founder power and full exit. To capture the underlying mechanism of the power–exit relationship, we conducted two experiments in which we randomly assigned decision makers to either a high- or low-power condition. We find that decision makers in the low-power condition are more likely to use a full exit via IPO than those in the high-power condition, and that frustration mediates this relationship. However, founders can also engage in partial exits, including a managerial partial exit in which the founder leaves management but keeps ownership, and a financial partial exit in which the founder divests ownership but remains in management. We find that the negative relationship between founder power and exit is more negative for full exits than for partial exits. With this paper, we contribute to the literature on exit by identifying a novel mechanism—frustration—underlying power’s influence on the likelihood and type of founder exit.

Adaptive maintain power signature scheme for power over ethernet system

Power over Ethernet (PoE) technology has been widely used in networking market for its space-saving, flexibility and low cost. As the PoE system needs to meet maintain power signature (MPS) requirements specified by the IEEE standard, it is important for powered device (PD) to draw a predetermined minimum current. If the PD current goes below the minimum current, the power sourcing equipment (PSE) assumes the PD has been disconnected and terminates operating voltage. If a fixed current is added to exceed the minimum current, a phenomenon of power wasting will be caused during standby or ultra-low power mode. This study proposes an adaptive MPS scheme to achieve power-saving and meet the MPS requirements. It consists of current comparator and MPS circuit to extract the periodic pulsed current for MPS requirements. The proposed scheme has been fabricated in 0.18 μm 100 V Bipolar-CMOS-DMOS process adding no extra pin and an area is 1.45 × 2.23 mm2. Test results show that the proposed interface sources a periodic pulsed current with a period of 318 ms and 25% duty cycle to tackle the issue of MPS absence in very low power condition.

Ultra low power mixer with out-of-band RF energy harvesting for wireless sensor networks applications

An ultra low power mixer with out-of-band radio frequency (RF) energy harvesting suitable for the wireless sensors network (WSN) application is proposed in this paper. The presented mixer is able to harvest the out-of-band RF energy and keep it working in ultra low power condition and extend the battery life of the WSN. The mixer is designed and simulated with Global Foundries ’ 0.18 μ m CMOS RF process, and it operates at 2.4GHz industrial, scientific, and medical (ISM) band. The Cadence IC Design Tools post-layout simulation results demonstrate that the proposed mixer consumes 248 μ W from a 1V supply voltage. Furthermore, the power consumption can be reduced to 120.8 μ W by the out-of-band RF energy harvesting rectifier.

Densification, microstructure and mechanical properties of an Al-14.1Mg-0.47Si-0.31Sc-0.17Zr alloy printed by selective laser melting

In this paper, the corresponding densification, microstructure, precipitate phase and mechanical properties of Al-14.1Mg-0.47Si-0.31Sc-0.17Zr fabricated by selective laser melting were detailly investigated. The experimental result shows that the densification of SLM specimens increased first and then decreased with energy density. Even at the same energy density, the relative densities of the samples are also different, and the printed sample has a high densification under the condition of low laser power and scanning speed. Two typical microstructures (fine grain zone and coarse grain zone) were formed inside the printed samples due to the formation of Al3(Sc, Zr) particles (coherent with the Al matrix) during the solidification process of SLM. As fabricated at 200 W and 500 mm/s, the average grain size of the SLM sample is 2.07 (Y-Z plane) and 1.72 μm (X–Y plane), and the maximum values of nano-hardness and tensile strength were 2.19 GPa and 510 MPa, respectively. The mechanical properties increased due to the combined effect of fine grain strengthening and dispersed distribution of precipitates in Al matrix. With a low density (2.537 g/cm3) and high tensile strength, the components fabricated by this alloy have more extensive spreading values and prospects for applying due to the excellent mechanical performance.

Exploring dark creativity: the role of power in an unethical marketing task

Creativity is seen as a significant driver for successful marketing activities. However, little attention is paid to its shady side and little research on the prerequisites for unethical behaviour of marketing experts and executives is on hand. In our experimental study, we examine the mutual influence of power, honesty-humility, and benevolent creativity as predictors for ‘dark creativity’ (the use of creative ideas for malevolent actions). Participants (N = 387) were randomly assigned to a high vs. low power condition (role of marketing director vs. marketing intern). Dark creativity was correlated to benevolent creativity, power motive, and honesty-humility, but did not depend on the power condition participants have been assigned to. In a hierarchical regression analysis only benevolent creativity and power motive predicted dark creativity. Additional variance was explained by role identification. This article is the first to investigate the impact of power on creativity in an immoral occupational task. Our findings support the concept of dark creativity as a combination of cognitive abilities and motivational aspects. The manipulation of power condition should be replicated in further research.

Preliminary experimental analysis of the surface topography formation during laser polishing H13 tooling steel using statistical characteristics of the surface amplitude distribution

Surface finish is one of the most important quality characteristics of fabricated components. To complement that, laser polishing (LP) is one of the advanced manufacturing surface finishing techniques that has been recently developed and successfully employed for improving surface quality without deteriorating the overall structural form through surface smoothing by melting and redistributing a thin layer of molten material. This paper proposes a statistical digital twin of the LP process and demonstrates the applicability of amplitude distribution statistical characteristics in the experimental analysis of surface topography formation during LP process. Initially, the thermodynamic transformation of the initial surface topography is considered by means of technical cybernetics and machine learning approaches to describe two of the most critical LP process components, namely: thermodynamic melting and solidification of both solid material and surface topography. To exemplify the effective application of statistical amplitude distribution characteristics, LP experiments were conducted with two different laser powers (25 W and 100 W) on flat and ground initial surfaces and resulting surface topographies were measured. Several amplitude distribution characteristics, such as roughness average value, averaged transverse profile as a W-shape, averaged transverse roughness profile, and probability distribution function were calculated. After that, actual molten material area, volume redistribution and final surface quality were comparatively analyzed. It was shown that the proportion between two components of the LP thermodynamic transformation and surface topography is critically dependent on laser power. As such, during low-power conditions (< 25 W), surface quality is predominantly determined by the thermodynamic transformation of initial surface topography and therefore only this component can be used for statistically reliable LP process modelling and digital identification. In summary, amplitude distribution characteristics have several advantages in building a comprehensive understanding of the molten material redistributing along and across LP line.

Do All Angry Customers Complain?

Customer complaints can shed light on organizations’ key performance practices, providing useful information for organizations to learn from their mistakes Since customer complaints should be regarded as a learning opportunity, it is important to identify what drives customer complaints. Through experimental designs using a failed service in the restaurant, we investigated whether all angry customers complain to the service provider and if not, what prevents them from raising their voice. Results showed that customers who felt powerful complained about a service failure as soon as they were angry; on the other hand, customers who felt powerless were not comfortable making face-to-face complaints in the restaurant although they were very upset. Hospitality practitioners who wish to learn from customer complaints must find ways to encourage customers to speak up when service failures occur. One simple way to enhance customer sense of power in the restaurant setting is to manipulate the menu. Our experiment showed that a subtle phrase embedded in a menu can affect customers’ sense of power. Our findings suggested that participants in the low-power condition indeed complained less in public, reducing opportunities for the service providers to hear from customers. Hospitality companies should understand the effect of power on customer behavior to increase customer feedback.

Study on flow modes of open natural circulation with low height difference under low power conditions

Open natural circulation systems are widely applied in the field of energy and chemical industries. Under some special conditions, open natural circulation systems with low height difference need to be applied, but research on this type of systems is not sufficient. In this paper, the flow modes of sucha natural circulation system were experimentally studied at low power level by adopting steam heating. In addition, the flow modes and physical phenomena of the natural circulation system were analyzed in detail under different heating power conditions. It is found that there are four flow modes at different power levels in the natural circulation system due to the influence of non-condensable gas and subcooled boiling. The inlet and outlet temperatures of heating section are analyzed in different flow modes. The result shows that the outlet temperature of heating section can be used as a judgment criterion for different flow modes.

Localization of Acoustically Tagged Marine Animals in Under-Ranked Conditions

A key technology in the movement tracking of marine animals is localization using acoustic transmitters. These are attached to marine animals and are detected by an array of receivers. Then, offline localization is performed by multilateration. However, due to the transmitter's low power and environmental conditions, emissions may be detected by only a limited number of receivers, causing localization ambiguities to arise. This work proposes a solution for such localization ambiguities. The proposed method assumes that the position of acoustically-tagged marine animals follows a hidden Markov model, such that localization ambiguities can probabilistically be resolved using a Forward-Backward algorithm. Our method is able to extrapolate the positions in a data series, as long as one sample in that series is picked up by three receivers, or if the identity of the receivers changes during tracking. Performance analysis shows that the localization accuracy of our method approaches the Cramér-Rao lower bound. Furthermore, to demonstrate the suitability of our method in a real sea environment, we have established a testbed that operated for three months, demonstrating localization of 20 acoustically-tagged sandbar sharks. Compared to the available solutions, roughly 20 times more location estimates were made; thereby, significantly increasing the impact of the test-site.

Gas shrinking laminar flow for robust high-power waterjet laser processing technology.

At present, waterjet-assisted laser processing technologies are disadvantaged by low coupling power and poor process reliability, which significantly affect processing efficiency and depth. To address these shortcomings, we propose herein a novel water-gas shrinkage-guided high-power laser processing (WSLP) technology. Firstly, the characteristics of the laminar flow and the light guiding of the water-gas coupled device are optimized. The laminar simulation results show that the water-gas contraction ratio and laminar flow length can be adjusted by changing the water/gas pressure and structural parameters. Secondly, light guiding simulation reveals with a 532 nm 1000W laser, the light guiding efficiency of the shrinkage interface can reach more than 95% within the range of the axial offset 22.1 mm, radial offset 0.62 mm and angular offset 15.8° of the laser focus. Compared with the traditional waterjet-assisted laser processing method, the anti-disturbance capability of the WSLP method is increased by 3.8 times in the axial direction, 2.3 times in the radial direction, and 1.5 times in the angle offset. Thirdly, the feasibility of the laser conduction and processing with this water-gas shrinkage method is verified by experiments. The formation conditions and the relationship of the water-gas laminar flow are investigated. The result shows that the laser coupling efficiency can reach 93% in the low power condition. The research can provide technical support for large depth laser precision machining, in the future.

Aluminum cladding oxide growth prediction for high flux research reactors

Aluminum cladding oxidation of research-reactor fuel elements at high power conditions has a disadvantageous effect on fuel performance due to the lower thermal conductivity of the oxide. The oxide growth prediction models available in the literature were mostly developed for low power conditions. To examine the applicability of the models to high power and high temperature test conditions, the models were studied by coupling with the most frequently employed heat transfer coefficient (HTC) correlations including the Dittus-Boelter correlation, the Colburn correlation, the Sieder-Tate correlation, and KAERI-developed correlation. The Griess model over-predicted the oxide growth while the KAERI-Griess model under-predicted the oxide growth for high power tests. The Kim model, coupled with the Colburn correlation, gave most consistent results with the measured data from two BR2 experiments. However, the Kim model was found to be inapplicable to the EUHFRR conditions at the peak power locations if it was coupled with the Dittus-Boelter correlation. A revision of the prediction models to more closely agree with the measured data was recommended. AG3NE and AlFeNi cladding types were tested in the E-FUTURE experiment, and a noticeable (although small) reduction in oxide thickness on the AlFeNi cladding was observed. However, this difference was believed to be only a secondary effect considering other uncertainties in model predictions, so no attempt was made to model the alloying effect.

In vitro comparison of direct plasma treatment and plasma activated water on Escherichia coli using a surface micro-discharge

In this study, our aim is to compare the inactivation of bacteria by direct plasma exposure of bacterial solution and plasma activated water (PAW) using a surface micro-discharge (SMD). Four potential factors which could affect both treatments were tested, namely the effect of low dose reactive oxygen species (ROS) pretreatment, enzymatic defence mechanism against oxidative stress, extracellular molecules, and mass transfer in liquid. We applied two power modes of the SMD, i.e. low power ozone mode and high power mode, to inactivate () in distilled water either by direct treatment (DT) or PAW. ROS pretreatment was tested by 30 M of , while superoxide dismutase (SOD) and catalase were used to investigate the effect of enzymatic antioxidant defense. Furthermore, the effect of extracellular molecules was examined by centrifuging and mass transfer in liquid by vortexing. In addition, reactive species in the solution were measured by titanium sulfonate, and nitrite/nitrate colorimetric method for , and and , respectively. Results indicate that vortexing and centrifuging significantly influence the bacterial reduction, while pretreatment could not induce resistance of bacteria against plasma treatment. Enzymatic antioxidants of SOD and catalase could potentially effect the inactivation and plasma chemistry yet only if the concentrations are sufficiently high. We assume that the continuous generation of peroxynitrite is crucial in plasma inactivation for both DT and PAW under high power condition, while under low power condition, long-term bactericidal affects are limited due to the decomposition of ozone by nitrite.

Can "slacktivism" work? Perceived power differences moderate the relationship between social media activism and collective action intentions through positive affect

We argue that the often-used critique of social media activism as merely a ‘feel-good’ mechanism can be countered by conceptualizing social media activism as a necessary type of collective action (i.e., consensus mobilization), incorporating theory on the benefits of positive feelings for activism, and by examining how power may affect these relationships. Women from two different samples (MTurk and university) were randomly assigned to recall a high- versus low-power experience, view real-world events of sexism, and then complete questionnaires assessing endorsement of social media activism, positive affect, and collective action intentions. A dual moderated mediation analyses at the second stage of mediation showed equivalency across two samples, at which point the single moderated mediation model was tested on the combined sample. The model was significant, such that among those in the high-power condition, endorsing social media activism was associated with greater positive affect, which in turn predicted greater collective action intentions. Among those in the low-power condition, however, this indirect effect was not significant. This study provides counter-evidence to the ‘slacktivism’ critique, contributes to theories of collective action, power and their integration, and identifies a possible intervention to enhance the effectiveness of social media activism.

Enhancement of mechanical and functional properties of welded NiTi by controlling nickel vapourisation

ABSTRACTThis work investigates the effect of nickel vapourisation on mechanical properties and superelasticity of a NiTi wire by selecting the highest and lowest power within a laser processing window. The dominant phase at room temperature changes from austenite to a mixture of austenite and martensite under low power and high power condition, respectively due to higher nickel loss in the high power sample. Furthermore, the high power sample has more deviation from base material texture (111)B2 that causes deterioration in mechanical properties compared with the low power sample with has 81% of base material strength. Better superelasticity of the low power sample (0.38% residual strain) was explained by the existence of the martensite phase and coarser grain structure in the high power sample.