Conversion Mode Research Articles

Review: Tree of Pearls: The Extraordinary Architectural Patronage of the 13th-Century Egyptian Slave-Queen Shajar al-Durr

Review: <i>Tree of Pearls: The Extraordinary Architectural Patronage of the 13th-Century Egyptian Slave-Queen Shajar al-Durr</i>

Frequency multiplexed metasurface for polarization conversion in full-space

In order to solve the problem of a single function in passive metasurface, a frequency multiplexed metasurface using full-space to realize different polarization conversion modes is proposed. On the basis of the fundamental theory of metasurface polarization transformation, a spliced coupling of multilayer structures was utilized. A compact architecture of five metallic layers and four dielectric layers was fabricated, and the principle analysis of polarization transformation was also performed. In the metallic part, two layers of oblique arrows and one layer of oblique rectangular patches constitute a low-frequency transmission structure, one layer of cross-shaped patches are constituted a high-frequency reflection structure, and one layer of rectangular patches constitutes an intermediate filter structure. Thus, it achieves a variable frequency polarization multiplexing function for transmission on one side and reflection on the opposite one. When the x- and y-polarized waves in the 6.3 GHz–8 GHz band are incident on the low-frequency unit side, they are converted into left- and right-hand circularly polarized transmitted waves, respectively. The axial ratio is less than 3 dB, and the transmission amplitude is up to 0.84 and 0.8. When 45° linearly polarization incident waves in 16.4 GHz–16.8 GHz and 16.9 GHz–18 GHz bands impinge on the high-frequency unit side, the cross-polarized wave reflection is realized. The measured and simulated results are in good agreement. The metasurface proposed in this paper has potential applications in communication frequency multiplexing and multifunctional integration.

Analysis and optimization of abnormal furnace pressure in a CFB boiler

An induced draft fan frequency converter fault during the operation of a CFB unit, the furnace pressure fluctuates greatly in the process of the fan switching from frequency conversion mode to power frequency mode automatically. By mean of analyzing the reasons of the abnormal event, corresponding improvement measures were put forward and the experience and lessons were also summarized. It provides a reference for preventing the occurrence of such events and dealing with similar events quickly for thermal professionals. Meanwhile, thermal workers could be reminded to pay attention to distributed control system (DCS) configuration management and the test work after configuration.

The starch-sugar interconversion mechanism during bulb development of Cardiocrinum giganteum (Wall.) Makino revealed by transcriptome and metabolite analysis

Cardiocrinum giganteum bulbs are rich in starch and natural compounds that benefit health. To better utilize the bulb starch of C. giganteum as an edible resource, understanding of the kinetics of starch and sucrose accumulation as well as the involved metabolic pathways in different developmental stages of the bulbs are required. In this study, we compared the dynamic changes in the transcriptomes and metabolomes of the bulbs over different developmental stages. A total of 43,692 differentially expressed genes and 508 metabolites were identified, which were clustered into nine co-expression clusters based on biological functions. Starch and sucrose metabolic pathways were identified at both the transcriptome and metabolome levels, revealing that activating the pathways of starch synthesis as well as sucrose synthesis and hydrolysis could be main conversion modes in starch-sugar interconversion. The data showed that the starch synthesis genes GBSS, SS3, GBE and ISA were expressed to highest levels at the stage of three-four years of C. giganteum development (c3y-c4y), concomitantly with the highest starch contents in this period. This revealed that the starch from the developing bulbs is optimally harvested at this stage. Meanwhile, sucrose synthesis genes were active and sucrose metabolites were maintained in balance during this stage, providing carbohydrate resources for starch biosynthesis. In the four-five year stage of development (c4y-c5y), the contents of sucrose metabolites increased, starch synthesis slowed down and sucrose hydrolysis genes were activated. Moreover, qRT-PCR analysis showed that the temporal expression patterns of starch and sucrose biosynthesis genes were largely consistent with the RNA-seq results. Taken together, these findings provide important information on the regulatory mechanisms of starch-sugar interconversion during C. giganteum bulb development.

Asymmetric Bidirectional Capacitive Power Transfer Method With Push–Pull Full-Bridge Hybrid Topology

Bidirectional capacitive power transfer technology makes it possible for energy sharing among multiple electronic devices. This article proposes an asymmetrical bidirectional power conversion topology to satisfy different input and output characteristics’ requirements and increase load variation tolerance. A π–T ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLC</i> – <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> ) resonant topology is designed for this bidirectional conversion mode with constant output voltage characteristics in both directions. A hybrid power flow regulation strategy is proposed by integrating multiple zero-voltage switching soft-switching operating points switching and phase-shifted mode. This method overcomes the problem of mixing two different type topologies (push–pull and full bridge) with two different power regulation modes (switch soft-switching operating points and phase shift), which provide a way to make two different chargers compatible. Simulation and experimental results verified the proposed method.

Tailoring of a bionic bifunctional cellulose nanocrystal-based gold nanocluster probe for the detection of intracellular pathological biomarkers

Gold nanoclusters with excellent fluorescence intensity, stability and biocompatibility have promising application prospects in the field of detection. Inspired by the growth behavior of sea squirts adhered to ropes, a novel bionic bifunctional cellulose nanocrystal (CNC)-based gold nanocluster probe was effectively constructed by directionally growing gold nanoclusters on CNCs modified with a specific DNA sequence. The constructed probe has excellent fluorescence properties and stability. The “ON or OFF” conversion mode of fluorescence was designed to detect different pathological markers in cells. In the “ON” mode, the probe readily combined with various sulfhydryl group containing markers (acetylcholinesterase, cysteine and glutathione) to produce fluorescence quenching and realize detection, the corresponding detection limits were as low as 0.015 mU/mL, 0.028 μM and 0.228 μM, respectively. Interestingly, the fluorescence of the probe could be regulated to the OFF mode via the assembly of the graphene oxide structure in accordance with Förster resonance energy transfer. The fluorescent probe with OFF mode could selectively recognize the carcinoembryonic antigen biomarker of malignant tumours via fluorescence enhancement, and its limit of detection was as low as 0.54 ng/mL. The as-developed novel strategy has positive significance for the early diagnosis of malignant tumours.

Laser wireless power transfer and thermal regulation method driven by transient laser grating

Wireless power transfer (WPT) technology uses non-conductive-wire methods to realize power transmission from the power-supply side to the load side, which is an advantageous energy supply method in long-distance, non-contact scenarios. Based on the photovoltaic (PV) effect, traditional laser WPT (LWPT) has the advantage of high transmission power. However, the cooling requirements of PV modules introduce additional structural composition and operating energy. In this paper, an LWPT (BeE-LWPT) technology based on the Seebeck effect is proposed, and a brand-new energy conversion mode is designed. Aiming at the limited hot area of the thermoelectric element periodically heated using the expanded beam laser, the improvement effect of the transient laser grating thermal regulation mechanism on BeE-LWPT is studied. Multiphysics simulations of the temperature response of the hot end of the copper plate modulated by the laser beam spot are carried out with commercial finite-element software. Compared with the traditional beam expansion method for temperature control, the proposed modulation method based on the transient laser grating has a more stable temperature response and a more uniform heating area, which means better thermal regulation effect.

Bio‐Inspired Wrinkled Photonic Elastomer with Superior Controllable and Mechanically Stable Structure for Multi‐Mode Color Display

AbstractColor is an excellent carrier of information between organisms. Photonic elastomers that convert abstract mechanical information into intuitive color information have shown great potential in various application fields. However, angular correlation of structural colors and monotonous color conversion mode affect the accuracy of material information reading and the applicability in diverse application scenarios. Here, inspired by a kind of bright blue spider‐ Poecilotheria metallica, a new wrinkled photonic elastomer structure is reported. Through wrinkling stretchable 1D photonic crystals (1DPCs), photonic elastomers with both one‐directional and omni‐directional angle‐independent brilliant structural colors are realized. It is worth noting that with the hybrid 1DPC and polydimethylsiloxane substrate support, the wrinkled photonic structure and structural color remain stable after 1000 strain cycles, and mechanochromic sensitivity can reach 3.25 nm/%, indicating strong structural stability and sensitive deformation performance under stress. More importantly, by comprehensively manipulating micro‐wrinkle structure and lattice spacing of the photonic films, the structural color can achieve delayed discoloration and invisible‐visible reversible switching performance only through a single strain direction. The proposed wrinkled photonic elastomers have a broad application value in the fields of visual strain sensing, wearable devices, and information encryption. Furthermore, it provides a new strategy for color regulation of photonic materials.

A novel approach for weak current signal processing of self-powered sensor based on TENG

Triboelectric nanogenerator (TENG) is a new high-efficiency electromechanical conversion mode proposed in recent years. When triboelectric nanogenerator is used as sensor, like other types of sensors, it can use current signal as sensing signal, but it outputs weak current signal with high impedance, which is not conducive to direct application. In this paper, a preprocessing method for weak current signal is proposed. The I/V conversion measurement method and the direct measurement method are theoretically analyzed, and the principle of parameter selection of circuit components is provided respectively. After that, the experiment of Contact Separated Triboelectric Nanogenerator (CS-TENG) is used to verify that the proposed I/V conversion measurement method has higher accuracy than the direct measurement method, and then the Rotary Triboelectric Nanogenerator (R-TENG) and the single electrode triboelectric nanogenerator (S-TENG) are used further verifies the design theory of the I/V conversion measurement method. Finally, it is concluded that the I/V conversion measurement method can convert the high impedance weak current signal output by TENG into a low impedance low voltage signal. Through reasonable component parameter selection, the measurement error can be controlled within 6 %, which can not only be used in current signal extraction of TENG, but also be expected to be used for current signal characterization in TENG when TENG is used as an energy harvester.

Interaction mechanism between nitrogen conversion and the microbial community in the hydrodynamic heterogeneous interaction zone.

To study the inorganic nitrogen in the process of interaction of river and groundwater and the changes in the microbial community, a vertical simulation device was used to simulate groundwater recharge to river water (upwelling) and river water recharge to groundwater (downwelling). The inorganic nitrogen concentrations in the soil and water solution as well as the characteristics of the microbial community were assessed to determine the inorganic nitrogen transformation and microbial community response in the heterogeneous interaction zone under hydrodynamic action, and the interaction mechanism between nitrogen transformation and the microbial community in the interaction zone was revealed. The removal rates of NO3--N in the simulated solution reached 99.1% and 99.3% under the two fluid-groundwater conversion modes, and the prolonged hydraulic retention time (HRT) of the oxidization-reduction layer in the fine clay area and the high organic matter content made the inorganic nitrogen transformation process dominated by microorganisms more complete. The denitrification during upwelling, dominated by denitrifying bacteria in Sphingomonas, Pseudomonas, Bacillus, and Arthrobacter, was stronger than that during downwelling. Dissimilatory nitrate reduction to ammonium (DNRA), controlled by some aerobic bacteria in Pseudomonas, Bacillus, and Desulfovibrio, was more intense in downflow mode than upflow mode.

Independently tunable bifunctional terahertz metasurface based on double-layer graphene

Artificial metasurfaces are one of the most promising candidates for realizing flexibly tunable devices. Here we propose a tunable bifunctional metasurface (TBM), which incorporates two layers of independently controllable hollow-patterned graphene that contribute to wideband linear polarization conversion mode and dual-band absorption mode, respectively. When working in linear polarization conversion mode, it can achieve the polarization conversion ratio (PCR) of over 96.1% and the relative bandwidth of about 42.2% in 3.98–6.11 THz; when operating in dual-band absorption mode, the absorptivity can reach 97.1% and 99.9% at 3.55 THz and 4.98 THz, respectively. The working mechanisms are elucidated through the eigenmode decomposition, transmission line model, surface current and field distributions. In addition, the influences of the chemical potential and relaxation time of graphene, main geometric parameters of the TBM, and incident angle of terahertz waves are discussed, implying that the TBM has excellent tunability and tolerance, and may provide a scheme for designing terahertz devices such as isolators, modulators and rotators.

Application of Tubular Reactor Technologies for the Acceleration of Biodiesel Production.

The need to arrest the continued environmental contamination and degradation associated with the consumption of fossil-based fuels has continued to serve as an impetus for the increased utilization of renewable fuels. The demand for biodiesel has continued to escalate in the past few decades due to urbanization, industrialization, and stringent government policies in favor of renewable fuels for diverse applications. One of the strategies for ensuring the intensification, commercialization, and increased utilization of biodiesel is the adaptation of reactor technologies, especially tubular reactors. The current study reviewed the deployment of different types and configurations of tubular reactors for the acceleration of biodiesel production. The feedstocks, catalysts, conversion techniques, and modes of biodiesel conversion by reactor technologies are highlighted. The peculiarities, applications, merits, drawbacks, and instances of biodiesel synthesis through a packed bed, fluidized bed, trickle bed, oscillatory flow, and micro-channel tubular reactor technologies are discussed to facilitate a better comprehension of the mechanisms behind the technology. Indeed, the deployment of the transesterification technique in tubular reactor technologies will ensure the ecofriendly, low-cost, and large-scale production of biodiesel, a high product yield, and will generate high-quality biodiesel. The outcome of this study will enrich scholarship and stimulate a renewed interest in the application of tubular reactors for large-scale biodiesel production among biodiesel refiners and other stakeholders. Going forward, the use of innovative technologies such as robotics, machine learning, smart metering, artificial intelligent, and other modeling tools should be deployed to monitor reactor technologies for biodiesel production.

CO-RABS Score

Study Objective: To determine the prognostic significance of a new score (CO-RABS), formulated by our Institute to classify the covid patients into mild, moderate, severe cases and also to compare it with the conversion AIIMS based classification. Patients and Methods: This is a retrospective study in which we have collected data from the medical records of patients who were admitted in our Hospital with covid infection during 2nd and 3rd waves of the pandemic. We have taken Comorbidities (CO), Respiratory rate (R), Age (A), Blood pressure (B) and SpO2 (S) of the patients at the time of admission to calculate an overall score (Abbreviated as CO-RABS). Basing on this score, the patients were classified into mild, moderate and severe cases. We then compared our CO-RABS score based classification with AIIMS classification using a statistical software. Results: We studied 727 patients (440 men, 287 women) and 99 patients died due to covid related complications. The ability to predict the prognosis was higher for our newly formulated CO-RABS score when compared to AIIMS classification. (AUC of CO-RABS 0.88 vs 0.82 of AIIMS; p &lt; 0.05). Conclusion: The ability of CO-RABS score to predict the prognosis of covid infection is higher than that of AIIMS/ICMR classification. Hence it can be used as a supportive tool in the covid management protocol along with all the other conversion modes of treatment.

Mathematical Model of a Local Grid with Small Modular Reactor NPPs

The technical and economic processes of the Local Grid, regional electricity system comprising small modular reactor nuclear power plants, renewable electricity generators, and electricity storage systems are investigated. Smart grid technologies are used in the management of such a system. In relation to the electricity system, the Local Grid acts as a consumer or producer of electricity depending on the price situation in the wholesale market and its own ability to balance the volume of electricity generation-consumption.&#x0D; The Local Grid market is considered to be perfect, otherwise the wholesale electricity market is characterized by imperfect competition. The mathematical model of the Local Grid is offered. The presented model adequately reproduces the characteristics of the interaction between the local market and the wholesale market. The mathematical model is generated in the form of the commitment problem for small modular reactors and electricity storage systems. The model reflects the technological limitations for the loading modes of small modular reactors and units of the energy storage system, which operate in the modes of direct and reverse energy conversion. In particular, the model reflects the shunting modes and start-shutdown modes of small modular reactors and charge-discharge modes of energy storage system units, which together determine flexibility of the operation modes for the entire power system. The commitment problem of small modular reactors of a nuclear power plant, units of the electricity storage system, and transmission lines connecting the Local Grid with the power system is a mixed integer programming problem with an objective function of minimized system costs.&#x0D; Cluster integer functions are used to reduce the dimensionality of the problems of mathematical modeling the loading modes of the Local Grid in the descriptions for the sets of the same type small modular reactors, as well as the same type energy storage units. The Local Grid model reproduces the modes of its disconnection from the system operator's network to increase nuclear safety in the event of a natural disaster or hostilities. The results of computational experiments on modeling the commitment modes of the local electrical grid are presented.&#x0D; The experiments used standard data on the volume of electricity consumption and its production from renewable energy sources. The results of the computational experiment confirm the adequacy of the suggested mathematical model for the Local Grid. The presented model is suitable for the use both independently – to analyze Local Grid functioning - and in combination with the models of electric power industry - to determine the impact of the Local Grids on the electricity system.&#x0D; The article is developed based on the results of the research carried out under target program “Support of State-Priority Research and Scientific and Technical (Experimental) Solutions of the Department of Physical and Technical Problems of Energy of the NAS of Ukraine for 2022 – 2023” with program expenditure classification code 6541230 (applied research).

A new control strategy of stopped-rotor aircraft based on manipulation model

PurposeThe purpose of this paper is to study the control strategy of transition mode of the stopped-rotor (SR) aircraft under the condition of redundant control and complex aerodynamic characteristics.Design/methodology/approachThis paper first proposes a transition strategy for the conversion between helicopter mode and fixed-wing mode. Then, aiming at the redundancy of the two control systems in the transition process, a control model is proposed, which greatly simplifies the control in conversion mode. Then, to facilitate the design of the control system, the Takagi-Sugeno model of the SR aircraft in transition mode is established. Finally, an explicit model tracking and tuning parameter stability augmentation control system is designed, so that the SR aircraft has a good stability during the transition process. Then, the outer loop control system of transition flight is designed.FindingsThe simulation results show that the control strategy proposed in this paper can realize the mode conversion well. It lays a solid foundation for the subsequent engineering flight test for the SR aircraft.Originality/valueThe work done in this paper provides ideas and methods for the flight control system design of SR aircraft in transition mode. The method of designing control model to solve the coordination of redundant control system is also applicable for other multimode aircraft, which provides a simple and convenient method for the multimode aircraft control.

Why KDAC? A general activation function for knowledge discovery

Deep learning oriented named entity recognition (DNER) has gradually become the paradigm of knowledge discovery, which greatly promotes domain intelligence. However, the activation function of DNER fails to treat gradient vanishing, no negative output or non-differentiable existence, which may impede the exploration of knowledge due to the omission and incomplete representation of the latent semantic. To break through the dilemma, we present a novel activation function termed KDAC. Detailly, KDAC is an aggregation function with multiple conversion modes. The backbone is the interaction between exponent and linearity, and the both ends are extended through adaptive linear divergence, which can surmount the gradient vanishing and no negative output. Crucially, the non-differentiable points can be alerted and eliminated by an approximate smoothing algorithm. KDAC has a series of brilliant properties, such as nonlinear, stable near-linear transformation and derivative, as well as dynamic style, etc. We perform experiments based on BERT-BiLSTM-CNN-CRF model on six benchmark datasets containing different domain knowledge, such as Weibo, Clinical, E-commerce, Resume, HAZOP and People's daily. The evaluation results show that KDAC is advanced and effective, and can provide more generalized activation to stimulate the performance of DNER. We hope that KDAC can be exploited as a promising activation function to devote itself to the construction of knowledge.

CALM: A software tool for rapid analysis and modeling of converted shear waves in wide-angle seismic data

Modeling of the converted shear waves is an issue of major interest in wide-angle seismic prospecting, which is indicative of the lithological properties in sediments, the crust and the uppermost mantle. The active-source seismological community has long called for a rapid, automatic and comprehensive modeling of these data. In this paper, we present a user-friendly software tool named CALM (standing for Converted wAve veLocity Modeling) for the converted shear wave modeling in wide-angle seismic data, which provides the first Graphical User Interface that is capable of determination of conversion modes/interfaces and automatic modeling of shear wave structures. The capacity of the presented software is demonstrated by a realistic case in the northern South China Sea continental margin, which analyzes the potential conversion modes of subsurface interfaces and obtains the crustal Vp/Vs structures from wide-angle seismic data.

Aerodynamic Uncertainty Quantification for Tiltrotor Aircraft

The tiltrotor has unique flight dynamics due to the aerodynamic interference characteristics. Multiple aerodynamics calculation approaches, such as the CFD method, are utilised to characterise this feature. The calculation process is usually time-consuming, and the obtained results are generally varied from each other. Thus, the uncertainty quantification (UQ) method will be utilised in this research to identify the aerodynamic inaccuracy effect on the handling qualities of the tiltrotor aircraft. The study aims to quantify the influence of the aerodynamic interference on the tiltrotor flight dynamics in different flight states, such as forward speeds and nacelle tilting angles, which can guide the flight dynamics modelling simplification to improve the simulation efficiency. Therefore, uncertainty identification and full factorial numerical integration (FFNI) methods are introduced to scale these aerodynamic uncertainties. The eigenvalue and bandwidth and phase delay requirements are presented as the failure criteria. The UQ calculation indicates that the uncertainties of the aerodynamic calculation significantly affect the handling quality ratings in two flight ranges: the helicopter mode and the conversion and aeroplane modes with higher forward speed (close to the conversion envelope). Furthermore, a sensitivity analysis is performed to identify the mechanism behind these influences. The results demonstrate that aerodynamics affect the pitching attitude, the pitching damping, and the velocity and incidence stability derivatives. However, the effects of the velocity stability and the incidence stability are the reason causing the handling qualities’ degradation in the helicopter mode and high-speed mode, respectively.

Aerodynamic Interference on Trim Characteristics of Quad-Tiltrotor Aircraft

The aerodynamic interference between the different components of quad-tiltrotor (QTR) aircraft were considered to analyze its influence on trim characteristics. A comprehensive method with the fixed-wake model was developed for multiple aerodynamic interactions, improving the accuracy of the flight dynamics analysis. Additionally, a more general control strategy was developed to tackle the redundant control issue of the QTR, improving its control efficiency by coordinating the authority relationship of various control surfaces across the flight range. Then, the trim features were calculated in the helicopter mode, conversion mode, and airplane mode, and the relevant results with and without interaction were compared. The results show that the aerodynamic interaction mainly influences the body’s vertical force, longitudinal force, and pitching moment. Furthermore, there are significant differences between collective and longitudinal sticks and pitch attitudes. The interference plays a major role in helicopter and conversion modes with a less-than-30-degree tilt angle.

Influence of space vehicle remote power supply on thermal regimes of solar batteries

The issues of ensuring the functioning of an additional energy-receiving channel for the onboard power supply system of a low-orbit spacecraft are considered. To compensate for the shortage of electricity on board the spacecraft, various options for remote power supply from the system of space power stations transmitting energy to the solar battery by laser radiation during periods of its forced inactivity are possible. Long shadow-sunlight periods of time are a distinctive feature of functioning of low-orbit spacecraft. During these periods the solar battery is idle, and, in addition, even in the daylight portion of the spacecraft's orbit, the energy output from the spacecraft may be reduced to almost zero during the operation of some special systems that require special modes of spacecraft orientation. Reception of energy from a CES with energy flux density higher than that of the solar flux may lead to overheating of the solar battery panel of conventional design, a decrease in its efficiency and even to its failure. Therefore, the analysis of thermal modes of reception and conversion of laser radiation energy which affect the energy efficiency of the solar battery is an important aspect of remote power supply. Relationships of a mathematical model for estimating the available power supply from the solar battery operating in the mode of optimizing control of its power are proposed. The results of approbation of the model for maintaining the safe thermal mode of the solar battery panels during remote power supply of the spacecraft are presented.