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Non-noble-metal-based electrocatalysts with superior oxygen reduction reaction (ORR) activity to platinum (Pt) are highly desirable but their fabrications are challenging and thus impeding their applications in metal-air batteries and fuel cells. Here, we report a facile molten salt assisted two-step pyrolysis strategy to construct carbon nanosheets matrix with uniformly dispersed Fe3N/Fe nanoparticles and abundant nitrogen-coordinated Fe single atom moieties (Fe@FeSA-N-C). Thermal exfoliation and etching effect of molten salt contribute to the formation of carbon nanosheets with high porosity, large surface area and abundant uniformly immobilized active sites. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image, X-ray absorption fine spectroscopy, and X-ray photoelectron spectroscopy indicate the generation of Fe (mainly Fe3N/Fe) and FeSA-N-C moieties, which account for the catalytic activity for ORR. Further study on modulating the crystal structure and composition of Fe3N/Fe nanoparticles reveals that proper chemical environment of Fe in Fe3N/Fe notably optimizes the ORR activity. Consequently, the presence of abundant FeSA-N-C moieties, and potential synergies of Fe3N/Fe nanoparticles and carbon shells, markedly promote the reaction kinetics. The as-developed Fe@FeSA-N-C-900 electrocatalyst displays superior ORR performance with a half-wave potential (E1/2) of 0.83 V versus reversible hydrogen electrode (RHE) and a diffusion limited current density of 5.6 mA cm−2. In addition, a rechargeable Zn-air battery device assembled by the Fe@FeSA-N-C-900 possesses remarkably stable performance with a small voltage gap without obvious voltage loss after 500 h of operation. The facile synthesis strategy for the high-performance composites represents another viable avenue to stable and low-cost electrocatalysts for ORR catalysis.

Using the resorcinol-formaldehyde (RF) resin as carbon source, core-shell structured carbon-coated zinc oxide (ZnO@RFC) was synthesized by cetyltrimethylammonium bromide (CTAB) assisted in-situ polymerization followed with carbonization process. The results showed that the ZnO particles were uniformly coated by an amorphous carbon layer. The excellent structural stability and high electrochemical performance depend it to be designed into carbon shell with a tunable thickness up to 14.4 nm, resulting in the ZnO@RFC anode delivers initial discharge specific capacity of 543 mAh g−1 and optimized 125 cycle life with capacity retention of 97.5% for Zn/Ni secondary batteries. And the effects of the thickness of carbon shell on electrochemical performance, corrosion and hydrogen evolution reaction are fully investigated. The results indicate that the carbon shell not only improves the electrical conductivity between ZnO particles but also increases the stability of ZnO in electrolyte.

Background The superior facet arthroplasty is important for intervertebral foramen microscopy. To our knowledge, there is no study about the postoperative biomechanics of adjacent L4/L5 segments after different methods of S1 superior facet arthroplasty. To evaluate the effect of S1 superior facet arthroplasty on lumbar range of motion and disc stress of adjacent segment (L4/L5) under the intervertebral foraminoplasty. Methods Eight finite element models (FEMs) of lumbosacral vertebrae (L4/S) had been established and validated. The S1 superior facet arthroplasty was simulated with different methods. Then, the models were imported into Nastran software after optimization; 500 N preload was imposed on the L4 superior endplate, and 10 N⋅m was given to simulate flexion, extension, lateral flexion and rotation. The range of motion (ROM) and intervertebral disc stress of the L4-L5 spine were recorded. Results The ROM and disc stress of L4/L5 increased with the increasing of the proportions of S1 superior facet arthroplasty. Compared with the normal model, the ROM of L4/L5 significantly increased in most directions of motion when S1 superior facet formed greater than 3/5 from the ventral to the dorsal or 2/5 from the apex to the base. The disc stress of L4/L5 significantly increased in most directions of motion when S1 superior facet formed greater than 3/5 from the ventral to the dorsal or 1/5 from the apex to the base. Conclusion In this study, the ROM and disc stress of L4/L5 were affected by the unilateral S1 superior facet arthroplasty. It is suggested that the forming range from the ventral to the dorsal should be less than 3/5 of the S1 upper facet joint. It is not recommended to form from apex to base. Level of evidence Level IV

In this letter, a planar array antenna with multiple-beams in orthogonal planes is proposed and investigated. A shared aperture is deployed for achieving a compact size, which is based on a cross transmitting network consisting of the substrate integrated waveguide (SIW) and the stripline. Two 1-D passive beamforming networks (BFNs) consisting of folded SIW Cassegrain reflectors are designed and integrated independently with the shared aperture. For demonstration, an 8 × 8 slot array at 26.0 GHz is designed and measured. In orthogonal planes, i.e., the xz plane and yz plane, six radiation beams have been achieved within ±40°, respectively. The proposed antenna is a good candidate for the millimeter-wave fifth-generation (5G) wireless applications.

The exact control of pore structure in carbon is desirable for offering a leap forward in a wide range of industrial applications, but the intractable hurdle relating to the anisotropic etching of carbon remains. Here, metal nano-drills are developed by which controllable pore size and adjustable hole depth can be rationally designed in both SP2- and SP2-SP3 hybridized carbon. A new catalytic drilling behavior is demonstrated, whereby the catalytic metal nanoparticles (Ru, Ni, Au, Pt, etc.) as drilling forces, accompanied by chemical etching, thermodynamically catalyze the decomposition of the surface barrier layer (K2CO3) and dynamically accelerate the anisotropic carbon etching rates. Subsequently, metal nano-drills open the enclosed internal spaces of activation carbonized microtubes (RCMT). Benefiting from the drilling structure featured by outer-inter connecting, RCMT exhibits 2.5 times higher Li2O2 accommodation capacity as the lithium-oxygen battery cathode and 2.8 times higher specific capacitance as the electric double-layer supercapacitor electrode than the carbonized microtube without the drilling process.

The colour quality assessment of reverse micelle-based (in octane or nonane medium) and conventional water-based dyed wool knitted fabric has been investigated using computer colour matching (CCM) approach. Both water-based and non-aqueous based dyeing methods exhibited no chromatic shift from the reflectance curves and established good linearity in the construction of calibration curves. The linearity of both calibration curves in terms of R2 value played a critical role in CCM. The colour yield obtained from reverse micellar dyed fabric samples was higher than the colour yield values from wool knitted fabrics dyed in water bath under different dye percentages. The CCM predicted concentrations were in good agreement to theoretical concentrations for both dyeing systems. To conclude, the results showed that reverse micellar dyeing in octane and nonane is capable of generating reliable colour recipes. The relative unlevelness indices (RUI) obtained from dyed wool knitted fabrics using reverse micellar approach reveal good to excellent levelness, which fulfills the requirements of the textile processing industry. TEM picture illustrated that reverse micelles are in nano-scale and this could enhance the dyeing effect of wool with reactive dyes.

A novel slot array antenna based on substrate-integrated double-line (SIDL) technology is proposed in this article. By using the SIDL technology, the feed network of the array is simplified and the high-order mode is suppressed. As a consequence, the proposed antenna can obtain a compact size, a wide bandwidth, and a high radiation efficiency. To excite the proposed antenna, the microstrip-to-SIDL transition is designed by adopting coupling slots at the bottom plate of the SIDL. A $16 \times 8$ element slot array antenna is designed and fabricated for verification by using multilayer printed circuit board (PCB) technology. The measured −10 dB impedance bandwidth is from 23.35 to 27.55 GHz (16.5%). A 21.6 dBi gain is obtained at the designed frequency of 25.8 GHz in the measurements. The measured 1 dB gain bandwidth and simulated radiation efficiency are 12.5% and 75%, respectively. The measured results agree well with the simulated results. The proposed antenna can be used to develop compact and high-efficiency millimeter-wave systems.

The magnetic gradient tensor is the spatial rate of change of the magnetic vector along the three axes of the Cartesian coordinate system. It is particularly suitable for aeromagnetic surveys because it is relatively insensitive to temporal changes and regional variations of the geomagnetic field. However, the complexity of the flight environment and defects in the existing calibration methods for airborne magnetic tensor gradiometers cannot guarantee the measurement accuracy of tensor data. Research shows that the generalized Hilbert transform can convert total-field gradients, measured over an extensive survey area, into the magnetic gradient tensor components, so a high-precision total-field gradiometer can be employed to calibrate a magnetic tensor gradiometer, using a generalized Hilbert transform calibration method (GHTCM). However, practical survey conditions cannot meet the requirements of the generalized Hilbert transform, which degrades the accuracy of GHTCM. Based on the theory of the generalized Hilbert transform, we first analyze the error sources and error mechanisms of the GHTCM according to the differences between real and ideal survey conditions and then build models to design an appropriate evaluation algorithm for the accuracy of the GHTCM. Simulation experiments based on the open-source flight simulator, FlightGear, and a practical flight experiment are designed. The results indicate that the proposed method can correctly evaluate the accuracy of the GHTCM. This evaluation algorithm is the basis of obtaining the high-precision calibration data for practical airborne magnetic gradient tensor in the survey.

A new application of network reliability is proposed to help analyze a business process performance in usual business activities. This research is to construct an easy, formal and mathematical tool to probe the health of daily-run business activities. A business activity consists of a series of value-added tasks, which are carried out by their related attenders, to meet business objectives. Traditional management behaviors include practices and skills to sustain the plan, sanction, management, and analysis of business activities. However, the assessment of activity performance remains a weak gap in analytic requirements. The approach proposed in this paper is one of the expected tools to fill the gaps in traditional management practices. The paper is to provide managers several new visions of modeling and analysis, which are not easily derived by traditional management practices. A distributor process with several scenarios to explain the approach are explored, and discussed.

Lithium–sulphur batteries (LSBs) have been drawing rapidly increasing research attention because of the low cost and high theoretical capacity of sulphur. The applications of LSBs however are hampered by poor stability caused by the shuttle effects of lithium polysulphides (LiPS), poor conductivities of sulphur, and sluggish redox kinetics of LiPS. Here, an advantageous carved N-doped carbon nanobox structure triply functionalized with an FeCoNi trimetallic sulphide was developed as a high performance sulphur host for LSBs. The strong chemical interactions toward LiPS, half-metallic conductivities, and catalytic activities toward redox reactions of LiPS, enabled through functionalization with FeCoNi trimetallic sulphide, work together to resolve the critical issues of LSBs. Moreover, the carved N-doped carbon nanobox structure serves as a nanoreactor that helps retain LiPS at cathodes and offers a confined space for fast local redox reactions. The triply functionalized carved N-doped carbon nanoboxes (S-FeCoNi@C-CNB) lead to high performance LSBs, delivering a high capacity of 1238 mA h g−1 at 0.1C and maintaining a decent capacity of 655 mA h g−1 at 2C. The LSB exhibits excellent stability with a low capacity decay rate of 0.049% per cycle over 200 cycle operations at 1C, indicating the success of S-FeCoNi@C-CNB in suppressing the shuttle effect.

Servo error pre-compensation (SEP) is commonly used to improve the accuracy of feed drives. Existing SEP approaches often involve the use of physics-based linear models (e.g., transfer functions) to predict servo errors, but suffer from inaccuracies due to unmodeled nonlinear dynamics in feed drives. This paper proposes a linear hybrid model for SEP that combines physics-based and data-driven linear models. The proposed model is shown to approximate nonlinearities unmodeled in physics-based linear models. In experiments on a precision feed drive, the proposed hybrid model improves the accuracy of servo error prediction by up to 38% compared to a physics-based model.

In this paper, we proposed an integrated hybrid antenna based on spoof surface plasmon polaritons (SSPPs) which combines with omnidirectional antenna (ODA) and the frequency beam scanning antenna (FBSA). The ODA is fed by the SSPPs and the operating principle of FBSA is based on the higher-order modes of the SSPPs. The radiation mechanisms of the proposed integrated antenna are that the low-pass transmission modes of SSPPs are used to excite the ODA and the higher-order modes of SSPPs are utilized to generate the frequency beam scanning waves. That is to say, the SSPP design not only serves as the feeding structure for the ODA, but also acts as the radiating element for the FBSA. Simulated results show that the proposed integrated antenna achieves two impedance bandwidths. Within the operating bandwidth 2.32 GHz to 4.42 GHz, the proposed integrated antenna achieves omnidirectional radiation patterns, which enables the simultaneous use for wireless local area network (WLAN) and 5 G applications. Meanwhile, from 11.45 GHz to 25.5 GHz, the proposed integrated antenna acts as a wide-angle frequency beam scanning characteristic and can be used for planar integrated communication systems. Additionally, a prototype of the proposed integrated hybrid antenna is fabricated and tested. The measured results have a good agreement with the simulated ones.

A series of Cu–M/Ce0.8Zr0.2O2 (M = W, Nb, Cr and Mo) catalysts were synthesized by a co-impregnation method, aiming for the removal of NO and CO under oxygen-rich conditions. The activity experiments confirmed that Cu–M/Ce0.8Zr0.2O2 can simultaneously catalyze NH3-SCR reaction and CO oxidation reaction. Moreover, the difference in the catalytic activity of the Cu–M/Ce0.8Zr0.2O2 catalysts was investigated by a series of characterization techniques. The results suggested that the sequence of the ratio of Cu+/Cu on the surface of the catalysts was as follows: 10Cu10CrCZ > 10Cu10NbCZ > 10Cu10WCZ > 10Cu10MoCZ, and the redox performance of Cu–M/Ce0.8Zr0.2O2 was consistent with this sequence. Besides, the introduction of Cr did not significantly improve the surface acidity as compared with the introduction of W, Nb and Mo. Excellent NH3-SCR and CO oxidation activity depended on the appropriate surface acidity and redox performance. Thus, 10Cu10NbCZ showed the most excellent NH3-SCR and CO oxidation activity.

This letter presents a novel probe selection method for multiple-input–multiple-output (MIMO) over-the-air (OTA) testing. It can effectively reduce the number of probes used in anechoic chamber, which further reduces the ports of the channel emulator. Two basic channel models are used to validate the performance of this method. The simulation results demonstrate that it can reconstruct the channel environment around the device-under-test in a multiprobe anechoic chamber with high accuracy. In addition, the impact of different probe configuration setups on the accuracy of test results are discussed.

A wide-angle frequency beam scanning antenna based on spoof surface plasmon polaritons (SSPPs) is proposed for planar-integrated communication circuits. The SSPP-based antenna is constructed by hole arrays etched on the standard $50~\Omega $ coplanar waveguide, which can achieve ultrawide bandwidth and wide-angle beam scanning from backward direction to forward direction as the frequency changes. The radiation mechanisms of the SSPP-based antenna are based on the higher-order modes of the structure, which have been analyzed by the dispersion curves and electric field distributions. The overall width of the proposed SSPP-based antenna is only $0.95\lambda _{0}$ (with $\lambda _{0}$ being the wavelength of the lowest working frequency). The simulated results show that the proposed frequency beam scanning antenna achieves a wide scanning angle of 129° over a frequency range from 11.7 to 50 GHz (for $\vert S_{11}\vert dB) with an average gain level of 12.38 dBi. The good agreements between the simulated and measured results validate the proposed design.

This letter reports a strategy of full-digital arrays with nonreciprocal transmitting (Tx) and receiving (Rx) beam patterns, for the first time, for 5G/6G wireless communications. The proposed full-digital array contains a smaller number of Rx channels than that of the Tx channels. The unequal number of Tx and Rx channels makes the transmitting and receiving patterns asymmetrical, which would not only release the burden of data processing but also reduce the hardware cost and power consumption of the entire system. Importantly, as compared with conventional large-scale beamforming arrays, the proposed strategy will not deteriorate the range of coverage at an instantaneous time. A 64-element full-digital beamforming array prototype was designed, fabricated, and characterized for a proof-of-concept demonstration.

In this study, a tellurium nanowire (NwTe) structure was synthesized as a template, and then a nanoscale zeolitic imidazolate framework 67 (Nano-Z67) was subsequently grown on it, denoted as Nano-Z67/NwTe. After pyrolyzed at a high temperature, the coordinated cobalt ion of Nano-Z67 and NwTe were transferred into the CoTe nanorods, which were encapsulated by a nitrogen-containing carbon nanowire (CN). The Nano-Z67/NwTe catalyzes the oxygen reduction reaction (ORR) with the electron-transfer number of 3.997 which is high than that of Pt/C with 3.995. The high ORR activity of Nano-Z67/NwTe attributed to the cobalt–nitrogen bond, carbon-nitrogen bond, and the NwTe-templated specific morphology, in which the CN serves as the conductive channel for electron transport. Remarkably, Nano-Z67/NwTe-750 not only demonstrates competitive performance compared with the Pt/C catalyst but also excellent stability.

Conventional thermoset coatings are prepared from petrochemical feedstocks which are nonrenewable, and the resulting coatings are not repairable. To extent the service life and meet the sustainable...

A ${W}$ -band large-scale substrate-integrated waveguide (SIW) cavity-backed slot array for high-gain applications is presented in this communication. The proposed antenna consists of a compact 16-way power divider and a $32\times33$ slot array. The 16-way power divider at the bottom-layer PCB provides equal-amplitude and alternative-phase excitation for 32 SIWs on the top layer PCB, and each of them supports 33 radiation slots. The loss along with the complexity of the feeding network is reduced by the implementation of alternative-phase excitation. To demonstrate the proposed slot array, a $4\times 33$ slot array excited by a two-way power divider is designed first. Then, the $4\times33$ slot array is extended to a $32\times33$ slot array by a 16-way power divider. To verify the proposed slot array, the designed array is fabricated and measured. The measured peak gain, radiation, and aperture efficiencies are 30.88 dBi, 42%, and 22.8% at 93.2 GHz, respectively. The proposed high-gain antenna is an excellent candidate for the high-frequency millimeter-wave (mm-wave) wireless system.

A compact planar directional coupled crossover with a wide fractional bandwidth is proposed in this letter, which is composed of overlapping planar 3-dB couplers based on the substrate integrated waveguide (SIW) and stripline techniques. In the proposed structure, the TE10 mode and TEM mode can be transmitted simultaneously without any interaction, which is helpful to design and integrate the SIW and stripline couplers for realizing a wideband directional coupled crossover with a compact footprint. A prototype with a center frequency of 26 GHz for 5G applications is designed and fabricated. The experimental results show that the measured crossover has high isolation among all ports and good directional coupling performance in orthogonal directions. The proposed crossover has a compact footprint and low loss, which can be a good candidate for developing the miniature feeding networks for multiple beam antennas.

This letter proposes a 400-GHz leaky-wave antenna with low sidelobe level (SLL) and low cross-polarization level (CPL). Tapered radiation slots are designed for achieving a low SLL, virtual electrical walls are deployed to remove the loss from metal sidewalls by using a high-order mode feeding network, and a symmetrical layout with alternative-phase excitations is adopted for the array to suppress the CPL. The conventional computer numerical controlled metal-milling and printed-circuit-board processes are used to fabricate the designed prototype. Experiments are carried out to verify the design. The measured peak gain and radiation efficiency of the fabricated prototype are 21.32 dBi and 34.65% at 395 GHz, respectively. In addition, its measured SLL and CPL are about −25 and −30 dB, respectively. The proposed antenna shows merits of the low cost, low SLL and CPL performance for potential terahertz applications.

A D-band low-loss mixed-mode filter with high selectivity is proposed and analyzed in this article. The transverse quintuplet/triple topology has been employed in the design with coupled overmode cavities using the TE $_{\mathrm {2N,1,0}}$ modes ( $N = 2,3,4, \ldots $ ) and TE $_{\mathrm {2N,1,0}}$ -like modes. Two transmission zeros (TZs) are generated in the upper and lower stopbands. The fractional bandwidth (FBW) and positions of the TZs can be flexibly designed by properly selecting the geometries of the proposed overmode cavity, which determines the frequencies of all resonating modes. To improve the frequency selectivity, multiple coupled overmode cavities, which have different spurious responses and TZs distributions, are cascaded for the designed filter. For demonstration purposes, two types of filter architectures are proposed for two D-band mixed-mode bandpass filters, respectively, which shows the design flexibility of the proposed method. The first filter is realized by cascading multiple overmode cavities through waveguide sections, and the second filter is realized by cascading overmode cavities through slots. Experiments are carried out to verify the second filter with TZs. The measured FBW3 dB is 17.18% from 128.11 to 152.19 GHz, the minimum insertion loss is around 0.33 dB, and the measured rectangle coefficient (BW40 dB/BW3 dB) is about 1.38. The measured results agree well with the designed ones, which verifies the proposed method. The proposed filter can be a good candidate for millimeter-wave and terahertz systems.

The variation in the morphology and electronic structure of copper during the electroreduction of CO2 into valuable hydrocarbons and alcohols was revealed by combining in situ surface- and bulk-sensitive X-ray spectroscopies with electrochemical scanning electron microscopy. These experiments proved that the electrified interface surface and near-surface are dominated by reduced copper. The selectivity to the formation of the key C–C bond is enhanced at higher cathodic potentials as a consequence of increased copper metallicity. In addition, the reduction of the copper oxide electrode and oxygen loss in the lattice reconstructs the electrode to yield a rougher surface with more uncoordinated sites, which controls the dissociation barrier of water and CO2. Thus, according to these results, copper oxide species can only be stabilized kinetically under CO2 reduction reaction conditions.

Aluminum alloy 7050-T7451 is widely used in aeronautical large structural parts, and high speed cutting is often used in machining. The serrated chip is a critical state for chip formation in high speed cutting, and its formation and control mechanism are of great significance for actual machining. To study the chip formation of high speed cutting aluminum alloy 7050-T7451, the chips at different cutting speeds are obtained by high speed cutting experiments. Combined with microscopic observation, the chip shape evolution, chip localization fracture process and mechanism of different cutting speeds are analyzed. The morphological evolution of chips and the mechanism of chip breaking during high speed cutting of aluminum alloy are revealed. According to the machined surface of the chip root and the angle of the chip, the formation mechanism of the curl radius formed by the chip is analyzed. The critical cutting speed of plastic-brittle transformation of aluminum alloy 7050-T7451 in high speed cutting is obtained by studying the critical condition for strip-to-serration transition of chip morphology.

Covalent organic frameworks (COFs) is made by covalent bonding of light elements, such as carbon, oxygen, nitrogen, boron and hydrogen, which can be flexibly synthesized as a porous material with low density, high permanent porosity and controllable sizes. This mini-review outlined the current understandings of mechanisms to yield a chemically stable COF and the use of these COFs to be adsorbents for removing adsorbates from waters. The research and development need to apply the COFs as industrial adsorbetns was discussed.

Early epoxy vitrimers in the literature rely on an inequivalent epoxy/anhydride stoichiometry and a large amount of catalyst to achieve a decent transesterification rate within the crosslinked netw...

The hot deformation behavior of a Ta-particle reinforced TiAl composite was studied. Ti–48Al–2Cr–2Nb– 0.2W(at.%)/20vol.%Ta metal matrix composite was fabricated by spark plasma sintering. The deformation behavior was investigated by hot compression tests at the temperature ranging from 1050 to 1200 °C and the strain rate ranging from 1×10−3 to 1 s−1. The constitutive equation containing true strain variables was established. The values of activation energy Q under different strain degrees are between 240 and 280 kJ/mol, which are lower than that of pure TiAl. Based on dynamic material modeling, the processing maps at various strain degrees were established, and the optimized parameters for hot working are 1050–1100 °C and 0.005–0.01 s−1. The microstructural evolution during deformation was characterized, which indicated that the dynamic recrystallization plays an important role in this process.

A novel wideband high-gain planar antenna array for $E$ -band backhaul applications is presented in this article. The antenna element is composed of a substrate integrated waveguide (SIW) cavity-backed patch and a stepped waveguide horn. The SIW cavity-backed patch is worked as wideband waveform and impedance transformer to excite the stepped waveguide horn on the upper layer. The stepped waveguide horn is employed to enhance the gain of the antenna element by increasing the radiation aperture. Based on the proposed antenna element, a $2 \times 2$ subarray with element spacing larger than a wavelength is designed. A groove, which works as secondary radiation source, is etched between the elements to improve the gain and suppress the high sidelobes of the $2 \times 2$ subarray. By taking the advantage of the groove, the $2 \times 2$ subarray achieves a maximum boresight gain of 17 dBi and an −10 dB impedance bandwidth of 21.8% from 70 to 87 GHz. For further enhancing the gain, a prototype including $16 \times 16$ elements is manufactured and measured. The experimental results confirm that the proposed antenna achieves the −10 dB impedance bandwidth of 22.4% from 71 to 88.5 GHz and a peak gain of 28.8–30.9 dBi. With the merits of a wider operating bandwidth, high gain, low profile, and low cross-polarization, the proposed antenna array is suitable for application in the $E$ -band wireless backhaul systems.

This paper presents a low-profile 400 GHz Airy beam generator using a reflective anisotropic metasurface based on a phase-only modified Fourier-transform-type method. To efficiently launch 2-D terahertz (THz) Airy waves of compact size, the proposed Airy-beam system adopts a folded topology consisting of a single-layered reflective metasurface and a polarizing grid. Different from the conventional dielectric lens or single-layered transmitting metasurface, the proposed folded reflective structure achieves the required cubic phase using a quartz-based reflective metasurface with reduced volume and increased efficiency. A quasi-I-shaped unit cell is proposed for the metasurface to manipulate the incident THz wave by efficiently converting the initial illumination to its cross polarization and simultaneously adjusting its phase with a range of $2\pi $ . A reflective metasurface and a THz polarizing grid are designed and integrated to show both the unique transverse acceleration behavior and the self-reconstruction property at the 400 GHz band. The simulated and measured results demonstrate that the proposed folded topology can produce the expected THz Airy beam with compact size and polarization conversion efficiency over 90%.

Defect clusters on the wafer map can provide important clue to identify the process failures so that it is important to accurately classify the defect patterns into corresponding pattern types. In this research, we present an image-based wafer map defect pattern classification method. The presented method consists of two main steps: without any specific preprocessing, high-level features are extracted from convolutional neural network and then the extracted features are fed to combination of error-correcting output codes and support vector machines for wafer map defect pattern classification. To the best of our knowledge, no prior work has applied the presented method for wafer map defect pattern classification. Experimental results tested on 20,000 wafer maps show the superiority of presented method and the overall classification accuracy is up to 98.43%.

This paper investigates the fuzzy position/force hybrid control for a class of 5-degree-of-freedom (DOF) redundantly actuated parallel robots. The position control law is designed based on the proportional-integral-differential (PID) for the 5-DOF redundantly actuated parallel robot. The fuzzy proportional-integral (PI) redundant actuation force control law is designed based on the position/force hybrid control structure for the 5-DOF redundantly actuated parallel robot. The optimum driving force is obtained in the presence of interference, and the force tracking performance of the fuzzy PI controller is better than the conventional PI controller under the interference condition. Based on the fuzzy position/force hybrid controller, the tracking performance of the closed-loop system for the 5-DOF redundantly actuated parallel robot is improved by using the fuzzy position/force hybrid controller and the interference is eliminated effectively in the control system design. Finally, the co-simulation results of ADAMS and MATLAB/SIMULINK are given to show the effectiveness and advantages of the proposed methods compared with the conventional PI controller.

This letter proposes a 140 GHz high-efficiency slotted waveguide antenna with a low-loss feeding network. The feeding network provides the same-magnitude but alternating-phase excitations for the slotted parallel-plate waveguide (PPW) array. The alternating-phase excitations are used to implement virtual electric walls (VEWs) for replacing the physical metal walls. Hence, the antenna efficiency is improved significantly. To verify the proposed method, an 8 × 8 slot array with the proposed feeding network is designed and fabricated, which has a fractional bandwidth of 10.17%, i.e., from 132 to 146.15 GHz. Experimental results show that the radiation and aperture efficiency of the prototype can be as high as 93.4% and 73.2%, respectively. The measured antenna has a peak radiation gain of 24.59 dBi at 137.5 GHz and a flat in-band gain. The proposed antenna provides a promising solution to develop high-efficiency upper millimeter-wave and sub-terahertz (THz) applications.

Producing acetaldehyde, an important industrial chemical, by direct catalytic non-oxidative dehydrogenation of ethanol presents many advantages over current production methods, including generating hydrogen. However, a stable, active, and selective catalyst is currently unavailable. This work demonstrates that the high activity and selectivity of nanoporous (np) NiCu for this reaction can be stabilized by keeping the catalyst in a metastable (“kinetically trapped”) state. Using a combination of in situ ambient-pressure and ex situ X-ray photoelectron spectroscopy, environmental transmission electron microscopy, and density functional theory calculations enabled correlating changes in surface composition with the changes in activity and stability upon treatment of np NiCu with H2 and O2. Reduction of Ni-doped nanoporous Cu by H2 exposure enhanced the initial activity but led to complete catalyst deactivation within ∼40 hours. In contrast, O2 pretreatment of the same catalyst increased both activity and long-term stability, with only 15% activity loss over 40 hours. The stability of np NiCu as a catalyst inversely correlates with the amount of metallic Ni at the surface, which is enriched by the H2 pretreatment, while the O2 pretreatment leads to a kinetically trapped Ni2+ subsurface state. This work emphasizes that detailed understanding of pretreatment-induced nanoscale structural and compositional changes is necessary to optimize catalyst performance.

In this communication, a bidirectional same sense circularly polarized (Bi-SSCP) endfire antenna array with reconfigurable polarization is proposed and implemented. First, a circular polarization (CP) reconfigurable endfire antenna element is realized by adopting two pairs of switchable electric dipoles, which have a 180° phase difference inherently. Along with the fixed magnetic dipole, the endfire antenna element can work at two CP states, i.e., left-hand CP (LHCP) and right-hand CP (RHCP) by switching the states of the two electric dipoles. Then, a Bi-SSCP endfire antenna array with polarization diversity is developed by using two identical endfire antenna elements placed back-to-back with a single feeding probe. For verification, prototypes of the designed endfire antenna element and Bi-SSCP endfire antenna array are fabricated and measured. The measured results show reasonable agreement with the simulated ones. The measured overlapped bandwidth for 10 dB return loss and 3 dB axial ratio of the Bi-SSCP endfire antenna array is from 5.7 to 5.9 GHz for the two CP states.

The approach of using reverse micelle with nonionic surfactant (poly(ethylene glycol), PEG)) as building block has been employed to investigate dyeability of wool fabrics with reactive dyes in a one-bath non-aqueous solvent system. Three colours were used and they were encapsulated in the core of the PEG-based reverse micelle under optimised process parameters (i.e. (i) Solvent volume to wool fabric weight ratio (v/w)=10:1; (ii) Surfactant/water mole ratio=0.04:1; (iii) Surfactant/co-surfactant mole ratio=l:8; (iv) Volume of water-pool for dye=0.5 ml; (v) Dyeing time=50 minutes; and (vi) Dyeing temperature=88 °C). Comparison of non-aqueous and aqueous-based (water-based) dyeing was conducted in terms of dyeability as reflected by colour yield and colour fastness properties. Experimental results revealed that the reverse micellar non-aqueous dyeing system can provide a better dyeing performance than aqueous-based dyeing system.

The terahertz (THz) dielectric constant ( e r ' ) and dielectric loss tangent ( tan δ ) of the commercial LTCC materials (Ferro A6M and DuPont 951), Al2O3 (ceramic and single crystal), AlN and β-Si3N4 ceramics were measured using a vector network analyzer (VNA) over the frequency range of 140–220 GHz and a time-domain spectrometer (TDS) from 0.2 to 1.0 THz. The results from the two instruments are compared with the literature and show good agreement and consistency. For Ferro A6M, e r ' = 6.06, tan δ = 0.012 at 1.0 THz. For DuPont 951, e r ' = 7.67, tan δ = 0.097 at 1.0 THz. For Al2O3 ceramic and single crystal, the measured THz dielectric properties are consistent with the reported works. The dielectric constant of AlN ( e r ' = 8.85) and β-Si3N4 ( e r ' = 8.41) ceramics in the THz region is a little lower than those reported for the MHz to GHz region. These results provide valuable and much needed reference information for device designers and material scientists.

This letter presents a continuous transverse stub (CTS) array antenna with high aperture efficiency, low sidelobes, and cross-polarization characteristics over an E -band. The antenna consists of a full-corporate-feed 32-slot CTS array and a 45° linear polarizer. A multiple-aperture excited parallel-plate waveguide structure works as a linear source generator to generate the quasi-TEM wave with a uniform amplitude distribution over the whole operating band from 71 to 86 GHz. The 45° linear polarizer contains two layers of slots, shifting the linear polarization from the principal E -plane ( φ = 90°) to the intended E -plane ( φ = 135°). The array antenna achieves the low cross polarization and sidelobe level (SLL) while maintaining high aperture efficiency. Measurement results show that the antenna has an aperture efficiency of over 74% with the peak gains of better than 37.9 dBi over the whole E -band, while the far-field SLLs in the intended E - and H -planes approach the ETSI class IV envelope standard.

Microplastics are prevalent in marine environments and seafood and thus can easily end up in human diets. This has raised serious concerns worldwide, particularly in Hong Kong where the seafood consumption per capita can be three times higher than the global average. This study focused on the green-lipped mussel Perna viridis, a popular seafood species which is subject to a high risk of contamination by microplastics due to its filter-feeding nature. P. viridis was collected from five mariculture sites in Hong Kong and assessed for its body load of microplastics using an automated Raman mapping approach. Microplastics were found in all sites, with an average of 1.60–14.7 particles per mussel per site, or 0.21–1.83 particles per g wet weight. Polypropylene, polyethylene, polystyrene and polyethylene terephthalate were detected among the microplastics, mainly as fragments or fibres in the size range of 40–1000 µm. It was estimated that through consumption of P. viridis, the population in Hong Kong could ingest up to 10,380 pieces of microplastics per person per year. These estimated rates were high compared to the values reported worldwide, suggesting the potential human health risk of microplastics in Hong Kong and adjacent areas.

The B-method, which provides automated verification for the design of software systems, still requires users to manually repair faulty models. This paper proposes B-repair, an approach that supports automated repair of faulty models written in the B formal specification language. After discovering a fault in a model using the B-method, B-repair is able to suggest possible repairs for the fault, estimate the quality of suggested repairs and use a suitable repair to revise the model. The suggestion of repairs is produced using the Isolation method, which suggests changing the pre-conditions of operations, and the Revision method, which suggests changing the post-conditions of operations. The estimation of repair quality makes use of machine learning techniques that can learn the features of state transitions. After estimating the quality of suggested repairs, the repairs are ranked, and a best repair is selected according to the result of ranking and is used to revise the model. This approach has been evaluated using a set of finite state machines seeded with faults and a case study. The evaluation has revealed that B-repair is able to repair a large number of faults, including invariant violations, assertion violations and deadlock states, and gain high accuracies of repair. Using the combination of model checking and machine learning-guided techniques, B-repair saves development time by finding and repairing faults automatically during design.

As one of the most popular beverages in the world, a large amount of coffee wastes known as the spent coffee grounds (SCGs) is generated daily. In this study, we report a polylactic acid (PLA) comp...

Defective die on a wafer map tend to cluster in distinguishable patterns, and such defect patterns can provide crucial information to identify equipment problems or process failures in the semiconductor manufacturing. Therefore, it is important to accurately and efficiently classify the defect patterns. In this paper, we propose a novel clustering-based defect pattern detection and classification framework for wafer bin map (WBM). The proposed framework has many advantages. Outlier detection and defect cluster pattern extraction can be done at the same time; arbitrarily shaped cluster patterns can be detected; and there is no need to specify the number of clusters in advance. Based on WBM property, the parameters used in the clustering algorithm are fixed so that parameter sensitivity can be avoided. Since the defect patterns are classified based on extracted features, no labeled data and no supervised classification training are needed and single-type patterns as well as mixed-type patterns can be found. Extensive experiments conducted on a real-world WM-811K dataset has shown the superiority of proposed framework. The proposed framework can also be used in a big data environment to accelerate performance.

Autofluorescence imaging (AFI) systems are widely used in the detection of precancerous lesions. Fluorescence images of precancerous tissue are usually red (R) or blue (B), so this kind of system has high requirement for colour recovery, especially in R and B channels. Besides, AFI system requires bulk data transmission with no time delay. Existing colour recovery algorithms focus more on green (G) channel, overlooking R and B channels. Although the state-of-art demosaicing algorithms can perform well in colour recovery, they often have high computational cost and high hardware requirements. We propose an efficient interpolation algorithm with low complexity to solve the problem. When calculating R and B channel values, we innovatively propose the diagonal direction to select the interpolation direction, and apply colour difference law to make full use of the correlation between colour channels. The experimental results show that the peak signal-to-noise ratios (PSNRs) of G, R and B channels reach 37.54, 37.40 and 38.22 dB, respectively, which shows good performance in recovery of R and B channels. In conclusion, the algorithm proposed in this paper can be used as an alternative to the existing demosaicing algorithms for AFI system.

Hot embossing is a novel technique for the cost-effective production of micro-parts. Misalignment between the top and bottom surfaces of a product that has double-sided microstructures reduces its functions. Most solutions involve repairing or reproducing the embossing mold, which increases the cost for the molding process. This study proposes a hybrid alignment platform that allows accurate positioning and angular alignment for the embossing processes. The hybrid alignment platform includes two units. The upper unit allows angular adjustment using a precision rotary table. The lower unit allows positional adjustment using two orthogonal micrometers. Calibration tests are conducted for a series of adjustment steps along the X, Y and C axis. Only one alignment step is necessary for each axis. The alignment platform allows rapid positioning and increases replicability. The hybrid mold adjustment platform is used to resolve a problem with gear misalignment and the problem of eccentricity in the production of micro-gears is effectively resolved.

Understanding interactions at the interfaces of carbon with ionic liquids (ILs) is crucially beneficial for the diagnostics and performance improvement of electrochemical devices containing carbon as active materials or conductive additives in electrodes and ILs as solvents or additives in electrolytes. The interfacial interactions of three typical imidazolium-based ILs, 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (AMImTFSI) ILs having ethyl (C2), butyl (C4) and octyl (C8) chains in their cations, with highly oriented pyrolytic graphite (HOPG) were studied in-situ by electrochemical scanning tunneling microscopy (EC-STM). The etching of HOPG surface and the exfoliation of graphite/graphene flakes as well as cation intercalation were observed at the HOPG/C2MImTFSI interface. The etching also takes place in C4MImTFSI at −1.5 V vs Pt but only at step edges with a much slower rate, whereas C8MIm+ cations adsorbs strongly on the HOPG surface under similar conditions with no observable etching or intercalation. The EC-STM observations can be explained by the increase in van der Waals interaction between the cations and the graphite surface with increasing length of alkyl chains.

In this paper, a systematic research campaign on eighth-mode substrate integrated waveguide (EMSIW) filters is reported. The sizes of these EMSIW resonant cavities are only one-eighth or one-sixteenth of a conventional SIW resonant cavity. Two different coupling topologies, i.e., electric coupling and magnetic coupling, are employed between two EMSIW resonant cavities, which are analyzed theoretically via the response of the structure and the relationship between the cavities. Both coupling topologies enable structural variations that possess advantages and flexibility of the second-order EMSIW bandpass filters (BPFs) designing. By utilizing these basic coupling mechanisms, multilayer board technology, and other practical techniques, a class of triple-order SIW BPFs with the merits of compact size and high selectivity are demonstrated. Specifically, several triple-order EMSIW BPFs composed of pure EMSIW cavities or comprised by combining EMSIW and quarter-mode SIW cavities are simulated, fabricated, and measured for verification.

A silicon heterojunction solar cell structure consisting of a gradient doping emitter layer, which possesses a potential to obtain high power conversion efficiency, is explored by the numerical simulation tool automat for simulation of heterostructures. We have demonstrated that the gradient doping solar cell has a higher open-circuit voltage than a uniform doping solar cell, due to the introduction of an additional electric field, which can achieve a better conversion efficiency, whereas their thickness and defect state distribution are identical. A high conversion efficiency of 29.5% is achieved by using a gradient doping for the n-type emitter layer with the same reference as the uniform doping. In addition, through the investigation of the effect of gradient doping, we find that the field-effect passivation can appropriately explain the interesting behaviors that the recombination rate is less sensitive to the defect density state, and that the open-circuit voltage is enhanced when increasing the doping gradient in the n-a-Si emitter layer.

Recently, a novel rechargeable Al ion battery (AIB) with high performance has been developed. Owing to its low cost, high-rate capability, excellent cyclability, and non-flammability, AIB provides a safe alternative to many commercial batteries used in the energy storage system. To improve its performance, identifying molecular structure and arrangement of chloroaluminate anion (AlCl4−) intercalated in the graphite layer remains a great challenge. In this work, operando analysis of X-ray diffraction (XRD) measurement and X-ray absorption (XAS) spectroscopy were performed to investigate the intercalation of AlCl4− anion and related molecular arrangement in the graphite layers. The intercalated stage and intercalant gallery height of graphite cathode electrode during AIB battery operation were observed to be stage 3 and 9.22 A, respectively. Furthermore, the spectral evolution from ex-situ XAS at the Al and Cl K-edge was associated with closely packed intercalation of AlCl4− molecules. With density functional theory (DFT) calculation, three simulated models of intercalated AlCl4− molecules in the graphite layer were revealed successfully, which explained possible molecular structures at different charging states. This analytical methodology paves the way for better understanding the structural transformation of molecular ions de-/intercalation in graphite layers.

This study synthesized the metal–organic framework-derived composite Fe–N–Co@C-800-acid-leaching (Fe–N–Co@C-800-AL) through co-doped iron and nitrogen atoms in a zeolitic imidazolate framework-67, followed by pyrolysis at 800 °C and the AL process. Fe–N–Co@C-800-AL was highly active in an oxygen reduction reaction, during which the number of transferred electrons (3.986) was close to an ideal four-electron transfer. In addition, Fe–N–Co@C-800-AL showed no obvious degradation, even after potential cycling of half-cell measurement (30 000 cycles). The prepared material exhibited a porous structure composed of nanoparticles (NPs) that were randomly distributed on poly-hydrocarbon structures with a Brunauer–Emmett–Teller surface area of 449.0 m² g–¹. X-ray photoelectron spectroscopy demonstrated that the synthesized Fe–N–Co@C-800-AL contained large amounts of pyridinic nitrogen and graphitic nitrogen, which could significantly enhance the activity of the oxygen reduction reaction. Furthermore, X-ray absorption spectroscopy of Fe−N−Co@C-800-AL revealed the existence of Co–Co and Fe–Fe and a lack of Co–Nₓ and Fe–Nₓ moieties, which means an oxygen reduction reaction may occur on the microstructures of N-doped carbon with wrapped metal NPs (Co or Fe). These findings revealed that Fe–N–Co@C-800-AL had a porous structure, high surface area, and the presence of functional nitrogen, thereby making it suitable for oxygen reduction reaction.

Imparting repairability to a thermoset coating without compromising other properties is desirable. In this work, a catalyst-free and repairable epoxy coating based on vitrimer chemistry was develop...

An ultra-wideband low-loss transition for the substrate-integrated waveguide (SIW) to the substrate-integrated coaxial line (SICL) is investigated. An experimental prototype with a centre frequency of 25.7 GHz has been designed and fabricated by using the multi-layer printed circuit board process. The measured results show the good performance of the proposed SIW-to-SICL transition, including a wide bandwidth of 53% (18.9–32.5 GHz) with reflection coefficients