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This work presents a beam element approach for the modeling and high-efficiency simulation of mechanical properties of 2.5D woven composite. For the beam element model, a technical scheme for the parametric modeling of 2.5D woven fabrics was produced. Considering the constraint relationship between the matrix and the fibers, we proposed a method for creating matrix beam elements. Then, a beam element solver was compiled to simulate the mechanical properties of the 2.5D woven composite. Meso-scale analysis of curved shallow-crossing linking 2.5D woven composite using the proposed model obtained the accurate tensile modulus. Full-scale analysis was implemented to simulate bending behavior of straight shallow-crossing linking 2.5D woven composite, and the simulation results agreed well with the experimental results. The above analysis could automatically complete modeling, analysis and post-processing in a relatively short time, reflecting the efficiency advantages of the method in this paper. [ABSTRACT FROM AUTHOR]

The fluctuation characteristics of wind, solar and electric load in microgrid are predicted by BP neural network. Based on forecast error, an economic robust optimization model is established considering uncertain variables, flexible load and carbon emission, solving by C&CG algorithm, which adjusted for individual uncertainty degree and overall conservatism of variables. The power of gas turbine is closely related to time-of-use price while the power of energy storage depends on the relationship of electrovalence and operation cost and flexible load is transferred to valley consumption time. As overall conservatism increases, the electricity purchase increases where microgrid refers to buy more electricity to resist risks, leading to 1897.4 yuan and 1007.2 kg of carbon emission added. Robust scheduling has lower costs compared to intra-day scheduling of 14.2 % decreasing when the intra-day electrovalence increases. Considering carbon quota constraint dispatching is more inclined to utilize gas turbine and energy storage while the total cost would rise by 247.6 yuan. With changing the operating cost of gas turbine, a balance point could be obtained in the game between economy and carbon emission. And there would exist an optimal equipment operation strategy when carbon emission is sufficiently enough, which realizes a balance of energy-carbon-economy. • Use neural network prediction errors as uncertainty set for robust day-ahead optimization. • Realize uncertainty degree adjustment for multi-variables and overall conservatism changing. • Explain the operation law along with boundary conditions of energy equipment under time-of-use price. • Obtain a balance point of economy and carbon emission simultaneously together with energy distribution. [ABSTRACT FROM AUTHOR]

Aims: Mycorrhizae and root exudates have been considered the two important pathways for nitrogen (N) transfer from legume to non-legume plants. The present study aimed to investigate contribution of the relative importance of arbuscular mycorrhizal fungi and root exudates in short-term N transfer. Methods: A field experiment was conducted to explore N transfer from alfalfa to maize under two different N application levels using 15N leaf labeling. Results: N transfer amount ranged from 7 to 10 mg N plant−1 from alfalfa to maize and significantly decreased (by 11%–22%) with N fertilizer application. Intercropping of 4 rows of maize and 6 rows of alfalfa with 30 cm intra-row spacing (IMA43) was the optimal intercropping mode, which increased N transfer, total N uptake and yield by 18%, 15% and 11%, respectively. The relative importance of arbuscular mycorrhizal fungi and root exudates on N transfer was dependent on soil N availability. Under no N addition, hyphal length density (HLD) of rhizosphere soil explained the largest significant amount (50%) of the variability in N transfer and crop yield. However, root exudates explained 77% of the variability in N transfer and crop yields with N fertilizer application. Conclusions: Our findings highlighted that N transfer is reliant more on arbuscular mycorrhizal fungi than root exudates in N-deficient soil, whereas root exudates play a more important role in N-fertilized soil. [ABSTRACT FROM AUTHOR]

• A heterogeneous energy coupling model is established for optimal operation and configuration. • Annual 8760 data of wind, solar and load are achieved and utilized. • Waste heat originated from CCHP is harvested by ORC system. • Carbon Singular Point shows the directionality of multi-objective optimization. Integrated energy system characterizes with improving cascade utilization rate of energy and efficient energy conservation and substantial carbon reduction. Aiming at the total annual cost and annual carbon emission of integrated energy system, the capacity optimal configuration model of integrated energy system based on the principles of cooling determining heat and heat determining electricity is established in this paper, considering energy complementary coupling characteristic and distribution ratio. Moreover, Non-dominated Sorting Genetic Algorithm-II combined with Technique Order Preference by Similarity to an Ideal Solution comprehensive solution model is adopted to achieve the optimal solution under Pareto solution set. The configuration result reflected that renewable energy is preferred, and there are more electricity storage devices with less electricity equipment. Furthermore, the optimal operation schemes of three typical season days are analyzed and compared, specifically presenting the effectiveness of the operation strategy proposed in this paper. In addition, waste heat originated from integrated energy system and harvested by ORC is analyzed herein, which highlights generating electricity with 2.19 × 104 kWh totally participating in operation of power subsystem and reducing CO 2 emissions by 15.056 tons. Furthermore, the sensitivity of carbon emission factors is analyzed, achieving that there is a Carbon Singular Point with 0.18 kg/kWh of natural gas emission and 0.98 kg/kWh of power grid emission respectively in the optimization process, which is significant for multi-objective optimization and construction of Integrated energy system. [ABSTRACT FROM AUTHOR]

ABSTRACT An eye-opening measurement circuit provides information about the signal quality of the high-speed data through the band-limited channel. Thus this information can be used to evaluate the channel performance, especially when the communication environments are changing constantly. By implementing this as a system-on-a chip, it is possible to realize the reconfigurable system such as an adaptable feed-forward equalizer, which will adapt itself through the changes of the communication channel. Moreover, the highly integrated single-chip eye-opening monitoring block can achieve more efficient and cost-effective communication chip test. In this article, we propose a new eye-opening measurement circuit, which can work up to 10 GHz. Using the fall time and rise time of the signal, which are affected by intersymbol interference, the corresponding characteristic is converted to DC values to assess the channel performance. The proposed eye-opening measurement circuit and tunable delay line are fabricated in 0.18-µm CMOS technology. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2136-2141, 2014 [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a transversal filter with winner-take-all variable gain amplifiers is investigated to improve the performance of a feed-forward equalizer. The proposed equalizer structure with nine gain cells has wide bandwidth and improved voltage headroom, at the same time achieving the low power consumption per gain cell. The proposed equalizer is fabricated in a 0.18 μm CMOS process and shows the successful compensation with 30 and 60 in backplanes with 3 Gbps signal. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2666-2670, 2013 [ABSTRACT FROM AUTHOR]

A parallel-strip line fed antenna with very wide bandwidth is presented in this article. This wideband antenna is designed as a combination of two individual antenna elements that are connected in a way inspired by the log-periodic antenna array technique. To miniaturize the size of the structure, metamaterial-based antennas are used as the basic radiating elements. The proposed antennas are designed on FR4 substrate and measured results show that it has a very wide bandwidth from 0.68 to 120 GHz with a VSWR < 3 for frequency range from 0.68 to 3.2 GHz and VSWR < 2 for the remaining bandwidth, with relative stable radiation characteristics. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2646-2650, 2012; this online at wileyonlinelibrary.com. DOI 10.1002/mop.27150 [ABSTRACT FROM AUTHOR]

This paper presents an improved two-antenna microwave passive direction finding system inspired by the human auditory system. By incorporating a head-like scatterer between two monopole antennas, both phase and magnitude information can be utilized to estimate the direction of arrival (DOA) of a microwave signal, thus eliminating ambiguities associated with phase wrapping at high frequency, just like human ears. In addition, better DOA sensitivity is demonstrated with the incorporation of the head-like scatterer. Both numerical modeling and experimental results of a simple X-band two-monopole configuration with symmetric and asymmetric scatterers are presented. [ABSTRACT FROM PUBLISHER]

In this article, the coupling coefficients of the coupled-resonator filters are extracted using the genetic algorithms (GA). To demonstrate the feasibility of the proposed method, filters with different orders and different characteristics are tested. In all cases, the parameters of these filters can be efficiently identified without any a priori knowledge. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011. [ABSTRACT FROM AUTHOR]

A low-profile, compact and easily integrated antenna for RF/microwave applications is presented in this article. The designed antenna works around 430 MHz and can be easily scaled to other frequencies. Metamaterial-inspired slot loop antennas are used as the radiating elements. To shrink the total size of the antenna, periodical structures are loaded to the original slot loop. It is found that with this modification, the total size of the antenna is reduced and the impedance matching of the antenna is improved. To further improve the performance of the proposed antenna, a floating ground plane and a parasitic slot were added, made possible by the multilayered structure of the antenna. As a result, the bandwidth and gain of proposed antenna are increased. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:219-223, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25654 [ABSTRACT FROM AUTHOR]

A narrow beam monopole antenna is realized by embedding the antenna within a periodic metallic wire array. The 2D wire array is designed to have an effective index of refraction smaller than unity (neff < 1) at the X-band frequencies (8–12 GHz), within which the antenna operates. The narrow beam effect due to the low refractive index of the wire medium is demonstrated in both simulation and experiment. Measured antenna properties including return loss and radiation pattern are in good agreement with simulation results. This simple and straightforward antenna design methodology can be applied at any microwave frequency. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2341–2345, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23653 [ABSTRACT FROM AUTHOR]

This paper presents an unsteady numerical study of the unsteady flow in the unscalloped radial turbine cavity considering the effect of computational sector size and sealing flow rate. A simplified U-shaped cavity with vanes and blades was simulated and the sealing efficiency was obtained using additional variables method. Unsteady low-pressure structures exist under a certain sealing flow rate, which is similar with axial turbine cavity, while the impact area is much larger. A comparison of computational domains sizes for 60° and 360° shows that whether the sector model can accurately predict the flow field depends highly on the number of low-pressure structures. As the sealing flow rate increases, the number and the speed of low-pressure structures at high radius decrease, and the corresponding low-frequency amplitude increases initially but decreases subsequently. The speed of low-pressure structure is positively correlated with its number, which seems contrary to the phenomenon observed in the axial turbine cavity. [ABSTRACT FROM AUTHOR]

Information security holds paramount importance in the contemporary information society. Here, a novel cryptography method is proposed based on the multi‐wavelength complex‐amplitude metasurface, which can achieve a high security level by generating a frequency‐selective key as an additional layer of protection. Moreover, the quality of the decrypted holographic images can be significantly improved by employing the complex‐amplitude encoding method and the modified visual secret sharing scheme, which adopts a new superposition operator to prevent fidelity loss. As a proof‐of‐concept demonstration, a prototype metasurface sample is designed, fabricated, and characterized, where the measured results agree very well with the numerical ones and the design goals. The proposed method can reinforce security level and improve fidelity of the decrypted message, rendering it appealing for applications in communication and anti‐counterfeiting. [ABSTRACT FROM AUTHOR]

In this article, a novel balanced wideband filter based on microstrip coupled lines is proposed. It features characteristics such as wide bandwidth, compact size, and good common-mode suppression. The proposed balanced filter was calculated analytically, simulated by full-wave electromagnetic simulator and validated by the measurements. The calculated, simulated, and measured results are in good agreement with each other. The experimental results show that it can allow the differential-mode signal to be transmitted with low insertion loss across a wide frequency band, whereas the common-mode signal will be well suppressed. The fractional bandwidth of the designed filter is 88%. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1139-1141, 2014 [ABSTRACT FROM AUTHOR]

Aims: Cereal can stimulate legume N fixation through competition for soil mineral N. In addition, organic acids in the rhizosphere can mobilize external nutrients, which may help nodulation. However, how much NO3− and NH4+ competition and organic acids in the rhizosphere of intercropped crops contribute to N fixation remains unclear and requires study. Methods: Field and greenhouse experiments were conducted to quantify effects of N competition and organic acids on N fixation in a maize/alfalfa intercropping system. Results: Intercropping increased nitrogen derived from the atmosphere (%Ndfa), nodules number, and leghemoglobin content by 43.66%, 85.53%, 141.05%, respectively, leading to significantly improved total N uptake and yield, compared to monoculture. The improved %Ndfa was not only due to the depletion of NO3−, but also significantly correlated with the decrease of NO3−/NH4+ ratio and the increase of citric acid in rhizosphere of alfalfa, which could mobilize soluble resources for N fixation under no N addition. Overall, 15.4%–21.5% of N fixed by alfalfa was transferred to associated maize, and the improved N fixation enhanced N transfer. Conclusions: Our findings provide a mechanism for how root interactions facilitate N fixation, highlighting the importance of NO3−/NH4+ ratio and citric acid in nutrient mobilization for N fixation. [ABSTRACT FROM AUTHOR]

In this work, an ultra‐wideband double slot Vivaldi antenna (DSVA) loaded with a novel wideband nonresonant metasurface is proposed to enhance the gain. The semi‐elliptical slots are etched on both sides of the ground plane of the DSVA to improve the current distribution. In addition, the nonresonant metasurface composed of WiFi‐shaped unit cells could maintain a stable high refractive index in the operating bandwidth of 1−18 GHz, which could bend the outgoing wave to the end‐fire direction. Both the original antenna and the proposed antenna are simulated, fabricated, and characterized. The measured results are in good accordance with the simulated ones. The return losses of both antennas are less than −10 dB in the frequency range of 2−13.4 GHz, while the gain of the proposed antenna is improved from 13.6 to 16.3 dBi with a maximum gain enhancement of 3.1 dB. [ABSTRACT FROM AUTHOR]

With the strong advancement of the global carbon reduction strategy and the rapid development of renewable energy, compressed air energy storage (CAES) technology has received more and more attention for its key role in large-scale renewable energy access. This paper summarizes the coupling systems of CAES and wind, solar, and biomass energies from the perspective of system topology, and points out the advantages and limitations of each system. It is shown that the coupling of wind energy and CAES is mainly combined in series and in parallel, and sometimes part of the wind power can be converted into thermal energy when coupled to CAES. The coupling between solar heat and CAES is an important form of coupling between solar energy and CAES. Solar-heat-coupled CAES mainly uses solar energy to heat expander inlet air. The coupling forms of solar energy and CAES are based on various CAES forms, various heat heating sequences, reheating, bottom cycle, and other factors. The combination of biomass and CAES is generally based on biomass gasification power generation technology. In the future, a wind–solar–CAES multiple coupling system is expected to become a promising large-scale form for the utilization of renewable energy, and this integrated system has great potential as a system configuration, but has some technical challenges. [ABSTRACT FROM AUTHOR]

Holography based on optical metasurfaces has attracted a steadily increasing interest. However, most of the optical metasurfaces usually suffer from limited number and fixed viewing angles of multiplexed holography images in one channel. Here, by modifying the Gerchberg–Saxton algorithm, a multiplexed holography at arbitrary‐planes is proposed at two arbitrary microwave frequency bands. As a proof‐of‐concept demonstration, two independent information channels can be established by a single metasurface through dual‐frequency meta‐atoms. The metasurface composed of 35 × 35 meta‐atoms can simultaneously produce four images with 45° and 60° viewing angles at 10 GHz and five images with vertical and horizontal viewing angles at 16 GHz. The experimental results verify the design concept, making it possible to generate multiplexed holography in arbitrary‐planes, and allowing multiplexed functionalities in a variety of applications such as microscopy, display, security, data storage, and information processing. [ABSTRACT FROM AUTHOR]

A novel design of circularly polarized broadband slot antenna with high gain, low profile, and low radar cross‐section (RCS) is proposed by employing polarization conversion metasurface (MS). By introducing sawtooth corner‐truncated square MS with diagonal gaps, a compact circularly polarized antenna composed of 4 × 4 unit cells is presented. It is found that a smaller MS slot antenna can achieve an impedance bandwidth of 42.9% (3.7–5.72 GHz) and a 3‐dB axial ratio (AR) bandwidth of 22.8% (4.55–5.72 GHz). Simultaneously, the MS can realize polarization conversion. The MS and its orthogonal units were arranged in a chessboard‐type pattern and applied as the radiator of a larger MS slot antenna, which was fed by a sequentially rotated feeding network. In addition, owing to the anti‐phase cancellation and scattering, the 5‐dB average RCS reduction can be obtained within the frequency range from 3.8 to 6.9 GHz. For verification, the proposed larger circularly polarized antenna was fabricated and tested. The operating bandwidth was measured as 44% (3.78–5.91 GHz) with a 3‐dB AR bandwidth of 39.6% and a high gain of 10.3 dBic. Furthermore, the larger antenna produces a useful RCS reduction from 3.7 to 6.7 GHz. The simulated and measured results are in good agreement. [ABSTRACT FROM AUTHOR]

High-resolution endoscopic optical imaging is a crucial technique in biological imaging to examine the inside organs. There is a trade-off between lateral resolution and depth of focus in such applications. Traditional Optical Coherence Tomography provides an increased depth range but falls short of desired resolution. The combination of both higher resolution and larger imaging depth of focus of metalens can improve the clinical utility of endoscopic optical imaging. In this work, we designed, analyzed, and fabricated a 500 µm diameter metalens operating at 1300 nm to achieve high resolution and large imaging depth of focus, therefore, addressing this need. The full width at half maximum and depth of focus for the proposed metalens are 3.10 and 286 µm, respectively. [ABSTRACT FROM AUTHOR]

This article presents a novel method for the forward modeling and inverse design of a class of Schiffman phase shifters using deep neural networks (DNNs). Since DNNs are capable of mapping the highly nonlinear correlations between inputs and outputs, we constructed a fully connected DNN to predict the electromagnetic (EM) responses of Schiffman phase shifters given their physical dimensions. Based on this fast and accurate modeling tool, a cascaded inverse design DNN was then built and trained to achieve instant on-demand phase shifter designs. This approach is versatile and can be easily modified to accomplish different design goals. To demonstrate its efficacy, we trained two DNNs to realize Schiffman phase shifter designs with different bandwidths (40% and 60%) and arbitrary phase shift targets (0°–180°). Simulation results and experimental verifications substantiate that their performances are comparable with the state-of-the-art designs. Moreover, we discussed the proposed methods’ potential in dealing with design tasks that are nonintuitive and beyond the scope of the existing approaches. We envision that this DNN approach can be extended to the design of various EM components including but not limited to antennas, filters, power dividers, and frequency selective surfaces (FSS). [ABSTRACT FROM AUTHOR]

Zoom lenses with variable focal lengths and magnification ratios are essential for many optical imaging applications. Conventional zoom lenses are composed of multiple refractive optics, and optical zoom is attained via translational motion of one or more lens elements, which adds to module size, complexity, and cost. In this paper, a zoom lens design based on multi‐functional optical metasurfaces is presented, which achieves large step zoom ratios, minimal distortion, and diffraction‐limited optical quality without requiring mechanical moving parts. Two embodiments of the concept are experimentally demonstrated based on polarization‐multiplexing in the visible and phase change materials in the mid‐infrared, both yielding 10× parfocal zoom in accordance with the design. [ABSTRACT FROM AUTHOR]

A direction of arrival (DoA) estimation technique for broadband microwave signals is proposed using a single ultrawideband antenna. It is inspired by the sound source localization ability of a human auditory system using just one ear (monaural localization). By exploiting the incident angle-dependent frequency response of a wideband antenna, the DoA of a broadband microwave signal can be estimated. The DoA estimation accuracies are evaluated for two antenna configurations and microwave signals with different signal-to-noise ratios. Encouraging the DoA estimation performance of the proposed technique is demonstrated in both simulation and experiment. [ABSTRACT FROM AUTHOR]

The electromagnetic shielding effectiveness of kenaf fiber based composites with different iron oxide impregnation levels was investigated. The kenaf fibers were retted for removing the lignin and extractives from the fibers and magnetized. Using the unsaturated polyester and the magnetized fibers, kenaf fiber based composites were manufactured by the compression molding process. The transmission energies of the composites were characterized when the composite samples were exposed under the irradiation of electromagnetic (EM) wave with a variable frequency from 9 GHz to 11 GHz. Using the Scanning Electron Microscope (SEM), the iron oxide nanoparticles were observed on the surfaces and inside the micropore structures of single fibers. As the Fe content increased from 0% to 6.8%, 15.9% and 18.0%, the total surface free energy of kenaf fibers with the magnetizing treatments increased from 44.8 mJ/m 2 to 46.1 mJ/m 2 , 48.8 mJ/m 2 and 53.0 mJ/m 2 , respectively, while the modulus of elasticity reduced from 2875 MPa to 2729 MPa, 2487 MPa and 2007 MPa, respectively. Meanwhile, the shielding effectiveness was increased from 30–50% to 60–70%, 65–75% and 70–80%, respectively. [ABSTRACT FROM AUTHOR]

Parametric interpolation has been widely used in robot control because of its advantages over traditional linear or circular interpolation. The NURBS interpolation based on S-shaped feedrate scheduling can realize the smooth continuous motion of robots, but it also faces two challenges. One challenge is that when the NURBS curve is split into multiple blocks, if one or more blocks are too short, the final feedrate profile is often discontinuous. The other challenge is that the NURBS curve cannot be obtained entirely due to calculation errors. In this paper, a high-precision NURBS interpolator based on S-shaped feedrate scheduling is proposed. In this interpolator, a bidirectional velocity scanning scheme is developed to effectively handle the too short split blocks of the NURBS curve. Meanwhile, an optimization algorithm is proposed to ensure the precision of NURBS curves. The feasibility and advantages of the proposed method are verified through case studies. [ABSTRACT FROM AUTHOR]

Multichannel devices, which can manipulate multiple distinguished wavefronts like a kaleidoscope, are preferably desired for compact systems with higher integration and smaller footprint. Particularly, multiband metasurfaces are one of the intuitive and effective approaches to expand the number of the operation channels in meta‐devices. In this work, a strategy to design four‐channel metasurface based on a novel single‐cell quad‐band meta‐atom is proposed for the kaleidoscopic wavefront manipulations. While illuminating a circularly polarized wave, the independent 2π phase shifts at four distinct frequencies can be obtained by the single‐layered substrate meta‐atom with almost theoretically maximal transmission amplitudes. As a proof‐of‐concept demonstration, a four‐channel metasurface is designed to realize a single‐vortex beam generator, a dual‐vortex beam generator, a meta‐hologram, and a focusing metalens in channels 1, 2, 3, and 4, respectively. The experiment and full‐wave simulation results agree very well with each other, validating the design concept. The proposed strategy has increased the number of operation frequencies for a single‐cell meta‐atom while guaranteeing the electromagnetic performance, and may lead to advances in a variety of multifunctional devices with a compact structure such as ultra‐thin metalenses, beam generators, and holographic displays. [ABSTRACT FROM AUTHOR]

Filtering light by coherence by metasurfaces would enable compact, integrable coherence filters. A recent such proposal centered on a metasurface of zigzags. Here, we show that spatial coherence filtering can be achieved at normal incidence with a similar zigzag metasurface and can be traced to the band structure of the leaky modes of the thin film structure. We fabricate a metasurface of zigzags etched through a gold film deposited on a GaAs substrate and measure the transmittance of long wave infrared radiation. Selectivity matches predictions based on the band structure of fully coherent radiation. Furthermore, the degree of coherence filtering is shown to be controlled by the Q-factor of leaky modes. [ABSTRACT FROM AUTHOR]

Full‐space metasurfaces have attracted significant interest due to their unprecedented abilities to tailor the electromagnetic wavefronts in both transmission and reflection half‐spaces. However, it remains difficult and challenging to achieve high‐efficiency complex‐amplitude modulation within a single‐substrate‐layer structure for circularly polarized (CP) waves, which can enhance the power distribution regulation. Herein, a universal design strategy for the frequency‐multiplexed full‐space meta‐device is proposed by employing a single‐substrate‐layer meta‐atom with complex‐amplitude modulations. The full‐space metasurface is composed of a subwavelength‐thickness substrate and two discrepant metallic layers, where a modified complementary split‐ring resonator and an electric field coupled resonator are selected to refract and reflect the CP incidences to the cross‐ and co‐polarized components at two distinct frequencies. Based on this emerging meta‐atom, a multifunctional bi‐spectral metasurface is designed and verified by both full‐wave simulations and experiments, which generates the quad‐vortex beam and the hologram in transmission and reflection modes, respectively. The proposed method employs a single‐substrate layer to maintain high efficiency, while incorporating the complex‐amplitude modulation, which has potential applications in imaging and communication systems. [ABSTRACT FROM AUTHOR]

Metasurfaces have provided a novel and promising platform for realizing compact and high‐performance optical devices. The conventional metasurface design approach assumes periodic boundary conditions for each element, which is inaccurate in most cases since near‐field coupling effects between elements will change when the element is surrounded by nonidentical structures. In this paper, a deep learning approach is proposed to predict the actual electromagnetic (EM) responses of each target meta‐atom placed in a large array with near‐field coupling effects taken into account. The predicting neural network takes the physical specifications of the target meta‐atom and its neighbors as input, and calculates its actual phase and amplitude in milliseconds. This approach can be used to optimize metasurfaces' efficiencies when combined with optimization algorithms. To demonstrate the efficacy of this methodology, large improvements in efficiency for a beam deflector and a metalens over the conventional design approach are obtained. Moreover, it is shown that the correlations between a metasurface's performance and its design errors caused by mutual coupling are not bound to certain specifications (materials, shapes, etc.). As such, it is envisioned that this approach can be readily applied to explore the mutual coupling effects and improve the performance of various metasurface designs. [ABSTRACT FROM AUTHOR]

This article presents the design of a microwave bandpass filter with tunable center frequencies and reconfigurable transmission zeros. The tuning of the center frequencies is realized by loading varactors at the ends of the λ/2 resonator. The reconfiguration of transmission zero is implemented through varactors in combination with tapped λ/4 stubs. The equivalent circuit models of the tunable filters are provided. The transmission zeros can be set to be at the lower side, the upper side, or both sides of the passband. The design concept is demonstrated by measurement results for both one transmission zero case and two transmission zeros case. The tuning frequency ranges are 680-890 MHz and 680-1020 MHz for one zero case and two zeros case, respectively. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1526-1531, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27628 [ABSTRACT FROM AUTHOR]

Accurate respiration measurement is crucial in motion-adaptive cancer radiotherapy. Conventional methods for respiration measurement are undesirable because they are either invasive to the patient or do not have sufficient accuracy. In addition, measurement of external respiration signal based on conventional approaches requires close patient contact to the physical device which often causes patient discomfort and undesirable motion during radiation dose delivery. In this paper, a dc-coupled continuous-wave radar sensor was presented to provide a noncontact and noninvasive approach for respiration measurement. The radar sensor was designed with dc-coupled adaptive tuning architectures that include RF coarse-tuning and baseband fine-tuning, which allows the radar sensor to precisely measure movement with stationary moment and always work with the maximum dynamic range. The accuracy of respiration measurement with the proposed radar sensor was experimentally evaluated using a physical phantom, human subject, and moving plate in a radiotherapy environment. It was shown that respiration measurement with radar sensor while the radiation beam is on is feasible and the measurement has a submillimeter accuracy when compared with a commercial respiration monitoring system which requires patient contact. The proposed radar sensor provides accurate, noninvasive, and noncontact respiration measurement and therefore has a great potential in motion-adaptive radiotherapy. [ABSTRACT FROM PUBLISHER]

With excellent photo-electric and electro-optical effects, the photorefractive spatial light modulators can work as optically addressed modulators in optical information processing systems and parallel optical computing systems. The photo-induced current pulses of the photorefractive spatial light modulator observed in the experiments are analyzed to conclude the characteristics, and to find the relationship between the properties of the current pulse and the structural parameters. Furthermore, the origin of the photo-induced current pulse is analyzed, and the methods to improve the operation speed of the spatial light modulators are proposed. The research results will be significant for extending the applications of the photorefractive spatial light modulators, and pushing ahead the research of all-optical modulation materials and devices for optical supercomputing. [ABSTRACT FROM AUTHOR]

A unified viscoplastic constitutive model with wide temperature adaptability is developed based on the basic framework of the Chaboche type model to capture the intricate cyclic viscoplastic behaviors of Haynes 230 subjected to isothermal low-cycle fatigue and fatigue-creep loads. By introducing effective aging time into drag stress in the hyperbolic sine viscosity function, the critical value of back stress and the additional hardening model, a rate-dependent model based on the dimensionless concentration of solute atoms or precipitates is further improved to realize simulation of dynamic strain aging effects. A multistage evolutionary approach to determining asymptotic value of back stress influenced by strain range and cumulative plastic strain is proposed to respond to cyclic hardening or softening evolved differently with the variation of temperature. For the fatigue-creep interaction, a rate or time dependent directional hardening cumulative model combined with the existing mean stress model is established. After the multi-step material parameter determination method is given, the capabilities of the proposed model are fully validated to accurately depict the mechanical behaviors of Haynes 230 for five representative temperatures. • A systematically modified viscoplastic constitutive model with wide temperature adaptability has been developed. • A rate-dependent model to fully reflect the effect of dynamic strain aging is given. • The idea of the multistage asymptotic value evolution of back stress is proposed to respond to cyclic hardening and softening. • A rate-dependent directional hardening accumulation model is proposed for fatigue-creep interaction. • The capabilities of the proposed model are fully validated to accurately depict the mechanical behaviors of Haynes. [ABSTRACT FROM AUTHOR]

Metasurfaces have enabled precise electromagnetic (EM) wave manipulation with strong potential to obtain unprecedented functionalities and multifunctional behavior in flat optical devices. These advantages in precision and functionality come at the cost of tremendous difficulty in finding individual meta‐atom structures based on specific requirements (commonly formulated in terms of EM responses), which makes the design of multifunctional metasurfaces a key challenge in this field. In this paper, a generative adversarial network that can tackle this problem and generate meta‐atom/metasurface designs to meet multifunctional design goals is presented. Unlike conventional trial‐and‐error or iterative optimization design methods, this new methodology produces on‐demand free‐form structures involving only a single design iteration. More importantly, the network structure and the robust training process are independent of the complexity of design objectives, making this approach ideal for multifunctional device design. Additionally, the ability of the network to generate distinct classes of structures with similar EM responses but different physical features can provide added latitude to accommodate other considerations such as fabrication constraints and tolerances. The network's ability to produce a variety of multifunctional metasurface designs is demonstrated by presenting a bifocal metalens, a polarization‐multiplexed beam deflector, a polarization‐multiplexed metalens, and a polarization‐independent metalens. [ABSTRACT FROM AUTHOR]

A new strategy for designing single‐band and dual‐band balanced bandpass filters (BPFs) based on a circular patch resonator is proposed in this study. By altering the output balanced ports of the balanced BPFs to inhibit or transport the TM31 mode of the circular patch resonator under the differential‐mode (DM) excitation, a single‐band or dual‐band balanced BPF can be realized. As the odd modes could be restrained under the common‐mode (CM) excitation, the balanced BPFs could feature high CM suppression in the DM passbands. Meanwhile, several perturbing tactics are introduced to improve the performance of the balanced BPFs. Specifically, perturbation vias are presented to disturb the electric field distribution to enhance the CM suppression in the DM passbands, and slots are applied on the circular patch resonators to perturb the current distribution to amend the second DM passband of the dual‐band balanced BPF. The proposed single‐band and dual‐band balanced BPFs are fabricated and characterized. Good agreement can be achieved between the simulated and measured results of the fabricated balanced BPFs, which validates the feasibility of the proposed design method. [ABSTRACT FROM AUTHOR]

The mechanisms underlying belowground processes in a perennial legume-dominated cereal/legume intercropping system were largely unknown. This study aimed to investigate whether alfalfa/maize intercropping can increase yield, phosphorus (P) uptake and utilization efficiency by influencing root morphology and distribution. Maize (Zea mays L.) and alfalfa (Medicago sativa L.) were grown in three different strip intercropping patterns and sole monocultures (monocultured maize, MM or monocultured alfalfa, MA), in field with or without P application from 2015 to 2018. Intercropping increased total yield by 68% compared with MM, and by 19% compared with MA; P uptake and P use efficiency of intercropping increased by 61% and 53% compared with the averaged monocultures, respectively, when considering all intercropping patterns and four-year results. This resulted in an enhanced land equivalent ratio (LER) based on yield and P uptake ranging from 1.13 to 1.62, with a higher LER observed under no P application. The intercropping pattern of four rows of maize and six rows of alfalfa with a row spacing of 30 cm had the greatest yield, leading to the highest LER among all the intercropping patterns. The positive complementary effect of intercropped alfalfa plays a crucial role in the observed advantages of maize/alfalfa intercropping. Intercropping increased alfalfa yield and P uptake. P uptake of alfalfa was positively correlated with the lateral root surface area. However, maize was at a competitive disadvantage under intercropping, the yield and P uptake was decreased compared to MM. P application increased total yield and P uptake averaged by 33% and 57%, respectively, compared to no P application. Phosphorus uptake efficiency was significantly higher under intercropping patterns (19.2%) compared to monocultures (9.0%) with P application. The complementary effect of intercropped alfalfa promoted the overall system yield and P uptake. The facilitative effects of maize/alfalfa intercropping were more pronounced in low P soils than with P application. The intercropping pattern of four rows of maize and six rows of alfalfa with a row spacing of 30 cm was recommended as the most productive cropping pattern. Maize/alfalfa intercropping are promising approaches to establishing productive and sustainable managed ecosystems, when designing a perennial legume-dominated cereal/legume intercropping system. [Display omitted] • Mechanisms underlying P uptake were studied at the root-soil interface in intercropping system. • Enhanced system yield and P uptake was due to complementary effect of intercropped alfalfa. • Superior water competition of alfalfa roots was critical to its enhanced yield and P uptake. • Four rows of maize alternated with six rows of alfalfa with a row spacing of 30 cm was recommended. • Appropriate maize/alfalfa intercropping help to establish productive and sustainable agroecosystems. [ABSTRACT FROM AUTHOR]

Meta‐devices have attracted great interest due to the unprecedented capabilities of manipulating wavefronts. Complex‐amplitude hologram can provide high‐quality images that can be free of ghost images and undesired diffraction orders. However, conventional meta‐holograms usually operate at a single band with phase‐only modulation. Here, a reflective 2‐bit meta‐hologram is proposed to operate with independent complex‐amplitude modulations at two frequency bands. The high‐efficiency meta‐atom is composed of a top perforated metallic layer, on which two C‐shape split ring resonators (CSRRs) are located in the centers of a circular hole and an annular slot. By tuning the sizes of the two CSRRs, dual‐band 2‐bit phase modulations can be individually achieved, while the amplitude profile can be continuously tailored at each band by rotating the corresponding CSRR without affecting the phase responses. Based on this emerging meta‐atom, a dual‐band bifocal metalens is demonstrated numerically and a bispectral meta‐hologram is validated both numerically and experimentally at two widely used communication bands. The proposed method features all desirable advantages of the coding metasurfaces with extra degrees of freedom by providing independent frequency control and amplitude modulation, which can provide great opportunities in multifunctional applications with enhanced performance and boosted information capacity. [ABSTRACT FROM AUTHOR]

In this paper, we present an achievable gradient refractive index in bi-continuous holographic structures that are formed through five-beam interference. We further present a theoretic approach for the realization of gradient index devices by engineering the phases of the interfering beams with a pixelated spatial light modulator. As an example, the design concept of a gradient index Luneburg lens is verified through full-wave electromagnetic simulations. These five beams with desired phases can be generated through programming gray level super-cells in a diffractive spatial light modulator. As a proof-of-concept, gradient index structures are demonstrated using synthesized and gradient phase patterns displayed in the spatial light modulator. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel design of broadband monopole optical nano-antennas. It is consisted of a corrugated half elliptical patch inside an elliptical aperture. By adjusting the dimensions of the elliptical patch and the elliptical aperture, the overall performance of the proposed monopole nano-antenna can be made remarkable broadband. Full wave electromagnetic simulations have been used to investigate the effects of different parameters on the nano-antenna performance. Moreover, the proposed broadband nano-antenna can support light waves with different polarizations. It is expected that the new optical antenna will pave the way towards the development of high performance optical antennas and optical systems. [ABSTRACT FROM AUTHOR]

Gradient index (GRIN) structures have attracted great interests since their invention. Especially, the recent advance in the fields of transformation optics, plasmonics, and nanofabrication techniques has opened new directions for the applications of GRIN structures in nano-photonic devices. In this paper, we apply Luneburg lens and its transformed counterpart to realize efficient coupling to plasmonic nano-waveguides. We first briefly present the general structures of Luneburg lens and generalized Luneburg lens, as well as the design process of flattened Luneburg lens applying quasi-conformal mapping techniques. After that, we study the performance of these lenses for coupling electromagnetic signals to nano-waveguides (the metal-insulator-metal nano-waveguide). Different coupling schemes are investigated. It is found that the proposed Luneburg lens based optical couplers can be used to provide broadband light couplings to plasmonic nano-waveguides under wide incident angles. [ABSTRACT FROM AUTHOR]

In this letter, a triple‐mode bandpass filter based on isosceles right‐angled triangular (RAT) resonator with three magnetic walls is proposed. To realize the triple‐mode filter, the RAT resonator is perturbed by two metalized via‐holes around the center. These via‐holes form an LC resonant unit with the patch. Also, the via‐holes make mode shifting of the TM010Z mode while not affecting the TM110Z mode in order to form the passband. The proposed filter is fabricated and measured. The center frequency is 5.51 GHz and the fractional bandwidth is 20%. The minimum in‐band insertion loss and return loss are measured to be 1.26 dB and 20.5 dB. The measurement results show that the filter has featured both compact size and excellent in‐band responses. [ABSTRACT FROM AUTHOR]

Aims: To investigate the relative contributions of pH, organic anions concentration, and phosphatase activity to rhizosphere soil phosphorus availability and crop phosphorus uptake in polycultures. Methods: A field experiment was conducted for three consecutive years in a split-plot design with main plots treated with two phosphorus levels and subplots treated with maize and alfalfa grown alone or intercropped. Results: Intercropped maize and alfalfa had 0.35 and 0.24 units lower rhizosphere pH, 28% and 30% higher total organic anions (TOA) concentration, and 21% and 41% greater acid phosphatase activity than those in monoculture. These changes in root exudates induced significant increases in rhizosphere phosphorus concentration of intercropped maize and alfalfa by 21% and 41%, and pH and TOA had greatest contributions, respectively. Rhizosphere phosphorus mobilization facilitated phosphorus uptake of intercropped maize, but this facilitation was offset by phosphorus uptake reduction due to decreased crown root surface area. Lateral root volume enhancement accounted for phosphorus uptake improvement of intercropped alfalfa by 86.6%, while rhizosphere phosphorus mobilization only had a 0.2% contribution. Conclusions: Rhizosphere pH and organic anions exhibit greater contributions than acid phosphatase activity in enhancing rhizosphere phosphorus availability. However, root surface area of maize and lateral root volume of alfalfa unveil greater influences on crop phosphorus uptake than rhizosphere pH and organic anions. [ABSTRACT FROM AUTHOR]

Reconfigurable beam steering components are indispensable to support optical and photonic network systems operating with high adaptability and with various functions. Currently, almost all such components are made of solid parts whose structures are rigid, and hence their functions are difficult to be reconfigured. Also, optical concentration beam steering is still a very challenging problem compared to radio frequency/microwave steering. Here we show a watermill-like beam steering system that can adaptively guide concentrating optical beam to targeted receivers. The system comprises a liquid droplet actuation mechanism based on electrowetting-on-dielectric, a superlattice-structured rotation hub, and an enhanced optical reflecting membrane. The specular reflector can be adaptively tuned within the lateral orientation of 360°, and the steering speed can reach ~353.5° s−1. This work demonstrates the feasibility of driving a macro-size solid structure with liquid microdroplets, opening a new avenue for developing reconfigurable components such as optical switches in next-generation sensor networks. Adaptive elements for optical beam steering are increasingly important to support nascent optical and photonic networks. This work presents a beam steering device based on a liquid droplet actuation method, capable of providing 360 degrees lateral steering with low energy consumption and a fast response time. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel IES combined with hybrid electrical/thermal storage and ORC is proposed. • Off-design of gas turbine, ORC's combined heat and power, and harvesting heat flexibly are considered. • SOC of battery energy storage system and HSD / CSD of thermal energy storage system are compared. • ORC's CHP mode is beneficial to decrease investment of hybrid electric/thermal storage and increase its planning capacity. • Bi-level optimization method is beneficial for IES's optimal dispatch, planning and renewal. Integrated energy system (IES) is characterized as a heterogeneous system, providing energetic, economic and environmental benefits by cooperating with multiple energy carriers. However, current studies rarely focus on utilizing hybrid electric/thermal storage in coordination with harvesting heat flexibly in IES, which should be further considered in the planning period. To this end, a novel IES combined with hybrid electric/thermal storage and multi-output organic Rankine cycle (ORC) is proposed. Considering operating modes of gas turbine, ORC's working manners, and converting patterns of harvesting heat in IES, comparisons of case study and operating characteristics on typical season days are analyzed. A bi-level optimal planning model of hybrid electric/thermal storage with ORC is proposed, consisting of a lower-level operating model and an upper-level planning model. Results show that there is the least operating cost of IES on typical season days under the off-design mode of gas turbine, ORC's combined heat and power (CHP) mode and harvesting heat flexibly, when enabling multi-flows to adjust thermoelectric ratio effectively. ORC's pure power generating mode in IES with low electrical load is not economically attractive, while ORC's CHP mode is beneficial to enhance ORC's consistent dispatching time and electricity producing amount. State of charge of battery energy storage system has similar varying patterns, while heat storage degree and cold storage degree of thermal energy storage system change differently owing to varying thermal loads. The IES is thermodynamically feasible and economically attractive thanks to the bi-level optimization, achieving optimal battery energy storage system capacity of 1773 kWh, thermal energy storage system capacity of 4823 kWh and ORC capacity of 91.25 kW. [ABSTRACT FROM AUTHOR]

Abstract A cryogenic air separation unit (ASU) with the implementation of vapor recompression column (VRC) and LNG cryogenic energy is proposed and investigated. To this end, three types of cryogenic rectification column for air separation are first illustrated, and their thermodynamic characteristics are evaluated by the first and second thermodynamic laws. The results show the purity and recovery ratio of product are determined by the total amount of heat duty and the scheme of heat distribution. Compared with the conventional double rectification column and internally heat-integrated distillation column, the VRC is the most suitable column for the ASU with use of LNG cryogenic energy as its lower demand of shaft work and minimum energy of separation. Based on the above analysis, adopting the cryogenic energy from product to cool the reflux and feed air is beneficial for producing vapor product in the proposed process. The operating pressure of ASU could be reduced by about 24%, and the cryogenic energy of LNG can be used efficiently and sufficiently with respect to the supercritical thermophysical property. By adding the air-aid refrigeration process, the proposed process also has the ability to produce liquid oxygen. Under the same oxygen purity and recovery ratio, the optimal results show the power consumption is about 6.9% and 11.1% lower than that in the previous studies in producing vapor and liquid product respectively, and the minimum energy of separation is improved by use of LNG cryogenic energy. Highlights • The unified governing equations of air separation is deduced. • The vapor recompression column has the lowest shaft work and minimum energy of separation. • The cryogenic energy of LNG can be used efficiently and sufficiently. • Energy consumption of the proposed process is less than that of conventional processes. [ABSTRACT FROM AUTHOR]

In this paper, a single-layer transmissive metasurface (TMS) is designed to generate orbital angular momentum (OAM) vortex waves with homogeneous radiation at microwave frequencies (e.g., 10 GHz). A single-layer TMS with the thickness of 3 mm (0.1λ0) is designed by well connecting the phase shift range of two elemental TMS structures. Specifically, two TMS structures—meandering patch-double meandering rings and meandering patch-single meandering ring with the unit-cell size of 7.5 mm (0.25λ0)—are used together to achieve high transmission efficiency (>0.8) and a large phase coverage range (>360°). In order to address issues such as uneven circumferential radiation and posterior lobe radiation and further enhance the efficiency of the TMS, the modified principle of Fabry-Perot cavity (FPc) suited for realizing the TMS to generate OAM vortex waves is proposed, analyzed closely, and applied. Specifically, an improved rectangular microstrip antenna is employed as a feeding source and a double square ring array is used to construct the backplane. A prototype of the proposed TMS with a FPc is designed, simulated, manufactured, and measured. The simulated and experimental results agree well, which demonstrate the feasibility of the presented design methodology. [ABSTRACT FROM AUTHOR]

Abstract: A miniaturized dual‐band filter using novel triple‐folded substrate‐integrated waveguide (TFSIW) resonators is proposed in this paper. The proposed TFSIW is enabled by specially designed folding structures, which leads to significant size reduction. The 2 lowest resonant modes, namely folded TE102 mode and folded TE101 mode in the TFSIW cavity, are utilized to achieve a dual resonance response with a small frequency ratio. To validate the design concept, a dual‐band filter operating at 1.91 and 2.32 GHz is designed, fabricated and characterized. Good agreement has been achieved between the simulation and measurement results. Moreover, the size of the proposed TFSIW resonator has been reduced for 86% compared with the conventional SIW resonator (assuming the same frequency ratio). [ABSTRACT FROM AUTHOR]

Due to strong nonlinear variation of supercritical liquid nature gas (LNG) and nitrogen (N 2 ) isobaric heat capacity with temperature and pressure, pinch point analysis is conducted for heat exchange process between LNG and N 2 and its effect on the air separation unit cooled by LNG cryogenic energy (CEASU) is studied in the present study. The effect of pinch point value, temperature difference at the cold end and pressure of N 2 on mass flow ratio (N 2 to LNG), approach temperature difference, energy consumption of CEASU and cryogenic energy utilization rate are analyzed in detail. For the heat exchanger process between LNG and N 2 , the different value of pinch point have little effect on its location, and increasing the temperature difference at the cold end effectively increases the mass flow ratio and decreases the approach temperature difference, while rising the pressure of N 2 leads to a valley value of the mass flow ratio, in contrast to a peak value in the approach temperature difference. For the energy consumption of CEASU, choosing the lower temperature difference at the cold end is good for the energy consumption and equivalent energy consumption per kilogram liquid production, but a large amount of LNG is needed and cryogenic energy could not be fully used; while the influence of pressure of N 2 on the energy consumption presents different variation trend. The result shows the energy consumption per kilogram liquid production of proposed CEASU is roughly 5–12% lower than that of convectional processes which the cryogenic energy is only used for cooling the nitrogen or the feed air. [ABSTRACT FROM AUTHOR]