Z-shaped Structure Research Articles

Electro-mechano-acoustical equivalent circuit model of z-structured piezoelectric transducer

To meet the demands of low frequency, small size, light weight and high power in the underwater application, a z-structured piezoelectric transducer (ZPT) is innovated, and its equivalent circuit representation is derived. In configuration, ZPT employs the bender beam to implement z-shaped structure for the compact design. In mechanics, ZPT utilizes the coupled longitudinal-bending vibration to produce a large output at a low frequency. In order to study the electro-mechano-acoustical behavior of ZPT, an equivalent circuit model is built based on the conception of analogy, and subsequently solved through the matrix-based methodology. The crux of this model lies in the derivation of the representation about the beam. The corresponding simulations indicate that the effect of the bender beam on ZPT is significant, and its connecting function and bending vibration makes it possible for ZPT to achieve the performance of compact structure and low frequency. The tests of the transducer prototype show that our ZPT has the size of Φ70 × 110 mm, the weight of ∼1.056 kg without housing and the transmitting voltage response (TVR) of 124.9 dB at the resonance frequency of 2.088 kHz. The experimental results show a good agreement with the equivalent circuit simulations of the ZPT. The benefits about low frequency, small size and light weight of the ZPT are attributed to its z-structured design and coupled longitudinal-bending vibration.

Tellurium-nanowire-doped thermoelectric hydrogel with high stretchability and seebeck coefficient for low-grade heat energy harvesting

To harvest low-grade heat energy from human body, flexible thermoelectric generators (TEGs) are highly necessitated and have attracted significant interests. However, developing novel thermoelectric materials with high stretchability and seebeck coefficient is still challenging. Here we report a tellurium-nanowire-doped (Te-NW-doped) PEDOT:PSS/polyvinyl alcohol (TPP) hydrogel with excellent mechanical and thermoelectric characteristics. The effect of Te-NWs doping on the thermoelectric characteristics has been systematically investigated and the optimized TPP hydrogel exhibits a large seebeck coefficient value of 787 μV K−1, a low thermal conductivity of 0.468 W m−1 K−1, and a high tensile strain value of ⁓ 400%. Furthermore, a wearable thermoelectric module with a staggered Z-shaped structure is developed to achieve a voltage output of 138 mV when it is applied on the human arm. After being integrated with a power management unit, the TPP TEG module enables the operation of electronic devices like a commercial calculator and a white LED, which exhibits great potential for applications in human heat energy harvesting and wearable electronics.

Helicity and topological charge tunable optical vortex based on a Hermite-Gaussian beam dynamically controlled folded-cavity resonator

Helicity and topological charge are two important characteristic parameters for vortex beam applications, including optical communications, optical manipulation and material processing, etc. In this work, a helicity and topological charge tunable vortex laser based on a folded resonant cavity is presented. In the resonant cavity, a Z-shaped structure is adopted and two deformable mirrors (DMs) are cascaded into the cavity as intro-cavity modulation elements. By applying different voltage combinations to the DMs, the Hermite-Gaussian (HG) beam with different indices and distribution orientations θ could be generated from the Z-shaped folded-cavity resonator. An extra-cavity astigmatic mode converter is adopted to convert the generated HG beam to the corresponding vortex beam with tunable helicity and topological charge, and the simulation results verified the feasibility of the presented vortex laser. In the experiment, the HGm,0θ beam (m = 1 to 10 and θ = −90 ° to 90 °]) and the vortex beam (topological charge l from ±1 to ±10 and left/right helicity) were flexibly achieved by simply adjusting the driving voltage combinations of the intra-cavity cascaded DMs.

A comparative study of chlorine and bromine species addition on the explosion limits of hydrogen-oxygen mixtures

In this work, we investigate the effects of chlorine (Cl) and bromine (Br) containing species additions on the pressure-temperature explosion limits of hydrogen-oxygen (H2-O2) mixtures computationally. It is shown that, with the addition of HCl, Cl2, HBr and Br2, the explosion limit evolves from being a non-monotonic Z-shaped curve to monotonic or maintains its non-monotonic response depending on the different types of additives. Specifically, with the addition of HCl to the mixtures, the limit always maintains the non-monotonic structure, while with the addition of around 18% of Cl2, it loses its Z-shaped structure. Compared with HCl and Cl2, more sensitive responses were found for HBr and Br2. With the addition of around 1% of HBr and 0.7% of Br2 to the H2-O2 mixtures, the limit's non-monotonic feature disappears rapidly, and becomes a monotonic curve. Further detailed kinetics analysis explains that after the addition of the halogen species, the radical competitions are different at the low- (P = 1.0 × 102 Pa), intermediate- (P = 1.0 × 104 Pa) and high- (P = 1.0 × 106 Pa) pressures respectively, resulting in the change of the dominant reactions. These findings enhance the understanding of Cl and Br containing species sensitization for the explosion limits of the H2-O2 mixtures and help to understand the kinetic interaction between the H2-O2 system and halogen.

Switchable Dual-Functional Metasurface for THz Absorption and Electromagnetically Induced Transparency

The metasurfaces based on nanostructure film play an important role in many fields. Usually, the properties and functions of metasurfaces are limited by their structure. Once the metasurface samples are processed, their functions have already been restricted. The dual-function device designed in this work utilizes the phase transition characteristic of vanadium dioxide (VO2). The entire layer of VO2 film is inserted between the double metal micro-nano structure. When VO2 film is in the metallic state after phase change, an isotropic narrow absorber is obtained in the terahertz (THz) region, which consists of a top Z-shaped meta-atom, a middle dielectric layer, and a bottom VO2 film. By adjusting structure parameters of VO2 film, perfect absorption is realized at the frequency of 0.525 THz with the overall absorption beyond 91%. When VO2 is in insulating state, the top Z-shaped meta-atom will interact with the bottom Z-shaped structure, and the resonance coupling leads to the appearance of electromagnetically induced transparency (EIT). The designed metal-VO2 hybrid metamaterial opens possible avenues for switchable functionalities in a single device.

Improving displacement of silicon V-shaped electrothermal microactuator using platinum sputter deposition process

PurposeThis paper aims to propose a method to reduce the resistance of silicon-based V-shaped electrothermal microactuator (VEM) by applying a surface sputtering process.Design/methodology/approachFour VEM’s samples have been fabricated using traditional silicon on insulator (SOI)-Micro-electro-mechanical System (MEMS) technology, three of them are coated with a thin layer of platinum on the top surface by sputtering technique with different sputtered times and the other is original. The displacements of the VEM are calculated and simulated to evaluate the advantages of sputtering method.FindingsThe measured results show that the average resistance of the sputtered structures is approximately 1.16, 1.55 and 2.4 times lower than the non-sputtering sample corresponding to the sputtering time of 1.5, 3 and 6 min. Simulation results confirmed that the maximum displacement of the sputtered VEM is almost 1.45 times larger than non-sputtering one in the range of voltage from 8 to 20 V. The experimental displacements are also measured to validate the better performance of the sputtered samples.Originality/valueThe experimental results demonstrated the better displacement of the VEM structure after using the platinum sputtering process. The improvement can be considered and applied for enhancing displacement as well as decreasing the driving voltage of the other electrothermal microactuators like U- or Z-shaped structures while combining with the low-cost SOI-MEMS micromachining technology.

Free and forced vibration analysis of a Z-shaped structure with multi-span elastic supports

In this paper, an in-plane Z-shaped structure with multi-span elastic supports is proposed to investigate the natural frequency and transmission response through employing in-plane governing equation and transfer matrix method. Based on the solutions of transverse vibration and torsional vibration, the total transfer matrix for the Z-shaped structure with multi-span elastic supports is derived. Furthermore, natural frequencies and mode shapes of the Z-shaped structure are calculated. Finite element simulation method (FEM) is conducted here to verify the theoretical results. In order to effectively evaluate the vibration reduction performance, transmission response of the Z-shaped structure under different boundary supports and multi-span elastic supports is analyzed. This work is significant for the vibration reduction of in-plane Z-shaped structure, especially the multi-span elastic support case in engineering applications.

Efficiency adjustable terahertz circular polarization anomalous refraction and planar focusing based on a bi-layered complementary Z-shaped graphene metasurface

Metasurfaces (MSs) have received great attention due to their wide application potentials in terahertz (THz) wavefront manipulation. Although great achievements have been obtained in MSs so far, the functionalities are almost static. The active adjustable MS-based devices are far less explored. In this paper, an efficiency adjustable MS composed of a dielectric substrate sandwiched with bi-layered complementary Z-shaped (CZS) structure graphene is proposed and investigated theoretically, which can control the THz circular polarization (CP) wavefront in transmission mode. The simulation results show that the MS structure under a Fermi energy level of 1.0 eV can realize CP conversion with efficiency of about 0.9, and the full range of a 2 π phase shift also can be achieved by changing the rotation angle of the CZS structure graphene along the wave propagation direction. More importantly, the transmission CP conversion efficiency is positively correlated with the Fermi energy levels of graphene. The anomalous refraction and planar focusing effect can be realized by the specific design of a spatial phase profile of the graphene MS, and the corresponding efficiencies can be adjusted by changing the Fermi energy level of the graphene. Adjustable graphene MSs have wide application prospects in the fields of communication, imaging, and other THz wavefront manipulation devices.

RADIOGRAPHIC OUTCOMES OF ANTERIOR CERVICAL DISCECTOMY AND FUSION SURGERY BY USING CUSHIONED TITANIUM CAGE

Purpose: Anterior cervical discectomy and fusion is considered as a standard procedure for treating cervical degenerative disc disease. This retrospective study aimed to analyze the radiographic outcome of using a novel cushion titanium cage (Baui Z-Brace Dynamic Fusion Cage). Methods: Fifty-seven patients who received either single-, double-, or three-level interbody fusion surgeries were enrolled. Data from initial status after surgery and postoperative follow-ups for five years were obtained. The patients were divided into three groups according to different levels of cage implantation: 1-level ([Formula: see text]), 2-level ([Formula: see text]), and 3-level ([Formula: see text]). Follow-up time and fusion rate of radiographs were subjected to evaluation. Results: The lateral view of plain radiographs manifests no evident cage subsidence ([Formula: see text][Formula: see text]mm) and dislodgment in 1-, 2-, and 3-level cage implantation. The follow-up time is three years in 1-level and two years in 2- and 3-level. The CT scans at the final follow-up among different levels of cage implantation manifested bony fusion. The measurement of the Hounsfield unit indicates the bone growth inside the cage compared with control case, demonstrating solid bony fusion among groups at the final follow-up. Conclusions: The data confirm that the specialized Z-shaped structure of the cushion titanium cage may provide the interfragmentary motion stimulating innate bony fusion for sustained improvement.

Nonlinear dynamics of a Z-shaped structure with validated global analytical mode shapes

The nonlinear partial differential governing equations of the planar motion of a Z-shaped structure are derived using Hamilton's principle. The 1:2 internally resonant global analytical mode shapes are validated by figure contrast and the modal assurance criterion (MAC). The partial differential governing equations are truncated into a two-degree-of-freedom ordinary differential system with the validated resonant global analytical mode shapes, and they are further investigated for internal and simultaneous primary resonances. The steady-state responses are studied, and numerical simulations of the system are performed. Complex nonlinear phenomena in the system, such as jumps, bifurcations, quasiperiodic motion and chaos, are observed under specific parameters. The parametric rule of these phenomena obviously depends on the accuracy of mode shapes. This work proposes a nonlinear analysis based on the quantitative validation of mode shapes, which may provide new insights into the optimal design of the parameters and the precise control of the motions of Z-shaped or other multibeam structures in engineering.

Novel Z-Shaped Structure of Lithium-Ion Battery Packs and Optimization for Thermal Management

AbstractThermal management of lithium-ion battery packs is a key technical problem that restricts the development of new-energy vehicles. The shape of air-cooled Lithium-ion battery packs is vital ...

Experimental and numerical study on thermodynamic characteristics in a Z-shaped evaporating pilot-flameholder

Reliable ignition and flame stability are crucial, particularly for the increasing expansion of flight envelopes. Herein, a novel Z-shaped evaporating pilot-flameholder is put forward to overcome critical challenges; further, the flameholder's ignition, blowout, and fully-developed flame characteristics under the operating conditions of turbine-based combined cycle combustors are experimentally investigated with the numerical flow field. The dynamic ignition process and the equivalence ratio of flame are acquired using a high-speed color camera and processed using an image-processing algorithm. The experimental results confirm the high ignition and blowout performance of the Z-shaped evaporating flameholder resulting from the superiority of its evaporating atomizer and Z-shaped structure. The ignition process of the Z-shaped flameholder simultaneously generates the diffusion and premixed flame types. The ignition performance of Z-shaped flameholder is significantly affected by the premixed degree of the pilot flame, which is a comprehensive index of the fuel atomization, evaporation, and turbulent mixing. The reflux rate and the premixed degree after ignition are little affected by the operating conditions, and the blowout performance is mainly influenced by the flow residence time and temperature. Further, the local equivalence ratio of the flame is acquired by calibrating the green/blue and equivalence ratios. Changing the equivalence ratio alters the double-reaction-zone feature in the Z-shaped evaporating flameholder. Under low fuel-lean conditions, flame stability is mainly contributed by the secondary reaction zone.

A miniaturized system for measurement of the refractive index of sub-microliter liquid

This study introduced the research and development of a portable and miniaturized system for the measurement of the refractive index of sub-microliter liquid based on a microfluidic chip. A technical method of double-beam interference, was proposed for use in the measurement. Based on this, by using a laser diode as a light source, changes in the refractive index were calculated by utilizing a complementary metal–oxide–semiconductor to detect the movement of interference fringes of the liquid. Firstly, this study simulated the effects of influencing factors on the interference infringes of two Gaussian beams, such as their spot sizes, distance between two beam spots, and detection range. Secondly, this research introduced the system design and construction of the double-beam interference method and analyzed the results of refractive index tests on sub-microliter aqueous glucose solutions with different concentrations. The measurement accuracy reached 10−4 refractive index units. This system has a compact structure and is rendered portable by using batteries for its power supply. The entire system is designed to be a double Z-shaped structure with a length of about 15 cm, a width of 5 cm, and a height of about 10 cm. It can be used to measure changes in the refractive index of sub-microliter to nanoliter liquids based on the use of a microfluidic chip.

Research in the Impact of Dynamic Loads for the Development of Pentice Designs when Sinking Skip Shafts

In order to protect workers engaged in shaft sinking works artificial protective equipment (buntons) with the support element from powerful I-beams or truss structures are used. They have to withstand enormous push loading, be strong, simple in design, have less labor input during construction and dismantling. Under shaft sinking in case of skip operational winding performance, a protective bunton can be exposed to the rock mass flow in the event of an emergency full skip run. To substantiate the variables and develop the design of pentices when sinking an active hoisting shaft, the skip falls time dependence on the changes in its fall height, taking into account the velocity and the air stream direction in the shaft, was established using mathematical modeling. LLC “SibGorComplexEngineering” together with the Department of Construction of Underground Structures and Mines of T.F. Gorbachev Kuzbass State Technical University have developed several new designs variants of protective buntons for vertical shafts sinking in case of operational winding performance. It is a Z-shaped structure of the offset in height, parallel to each other of upper and lower protective buntons, bushed with sloped reflective metal sheets and it is interconnected by a vertical division wall.

A novel double-incidence and multi-band left-handed metamaterials composed of double Z-shaped structure

In this paper, a novel double-incidence and multi-band left-handed metamaterial (LHM) was presented based on coplanar electric and magnetic resonators, whose structure is composed of two orthogonal Z-shaped metallic strips on each side of the dielectric substrate respectively. Both the double Z-shaped LHM for electromagnetic wave parallel and normal incidences are discussed. The structure exhibits two LH pass-bands and one right-handed pass-band when electromagnetic waves are incident parallel to the substrate, while it can achieve multiple LH pass-bands under normal incidence with the same structure and only single size of Z-shaped strips. By means of theoretical analysis, building equivalent magnetic resonance circuit models, numerical simulation, extracting the effective permittivity, permeability from S parameters and the experimental measurement, the left-handed properties are analyzed and verified. The fabricated double Z-shaped metamaterials will create a new way to prepare the electromagnetic cloak which is suitable for multiple frequencies, and the cloak of infrared or visible frequency, especially with the same structure and in same size from different incident directions.

Circular-polarization-dependent mode hybridization and slow light in vertically coupled planar chiral and achiral plasmonic nanostructures

We numerically studied a square array of plasmonic nanostructures with the unit cell composed of a z-shaped chiral structure and an achiral strip pair. Circular-polarization-dependent mode hybridization between the z-shaped structure’s radiant mode and the strip pair’s subradiant mode is observed: the resonance amplitudes of two hybrid modes are different for left-handed and right-handed circularly polarized waves, and an electromagnetically induced transparency-like transparency window is obvious for only one circularly polarized wave. Consequently, slow light with small group velocity is only evident for the corresponding polarization state.

Electrothermal behavior and terahertz emission properties of a planar array of two Bi2Sr2CaCu2O8+δ intrinsic Josephson junction stacks

We report on the investigation of the electrothermal behavior and the terahertz (THz) emission properties of two nearby Bi2Sr2CaCu2O (BSCCO) intrinsic Josephson junction stacks, using a combination of electric transport and THz emission measurements plus low temperature scanning laser microscopy. We start with a compact BSCCO stack (placed in a z-shaped structure between two BSCCO electrodes) with lateral dimensions of and height, consisting of about 480 junctions. After characterization, a 200 nm wide slit was introduced by focused ion beam milling, splitting the stack into two halves connected by continuous superconducting electrodes. In a third step, the upper electrode was also split, leading to a structure where the two stacks can be biased separately. In all configurations hot-spot formation was observed. Despite the separation into two stacks only a single hot spot formed, which, depending on the bias condition, could either be located in one of the stacks or extend into both stacks with its center in the slit. In none of the structures it was possible to achieve mutual synchronization of the two stacks, indicating that additional synchronizing elements or the presence of a base crystal as for mesa structures may be necessary for the operation of parallel array structures.

Controlled dynamic helicity of a folded macrocycle based on a bisterephthalamide with a twofold Z-shaped structure.

Dynamic helicity in a folded macrocycle and control of the helical preference are described. We designed macrocycle 1 with a dual mode of folding through the integration of two flexible units that are arranged twice to form a cyclic structure. As a folding unit, we used a terephthalamide skeleton and a Z-shaped hydrocarbon: the former acted as a control unit to induce a preference of a particular sense of dynamic helicity and the latter was just a spacer. A terephthalamide unit provided a binding site for capturing a ditopic hydrogen-bonding guest when it adopted helically folded syn forms (M/P). Thus, only the terephthalamide unit controlled the helical sense of dynamic helicity in a folded macrocycle through the supramolecular transmission of chirality upon complexation with a chiral ditopic guest. In addition, chirality on a host could also contribute to the control of the helical preference in a folded macrocycle, which led to exceptionally enhanced chiroptical signals.

Intact Functional Fourteen-subunit Respiratory Membrane-bound [NiFe]-Hydrogenase Complex of the Hyperthermophilic Archaeon Pyrococcus furiosus

The archaeon Pyrococcus furiosus grows optimally at 100 °C by converting carbohydrates to acetate, CO2, and H2, obtaining energy from a respiratory membrane-bound hydrogenase (MBH). This conserves energy by coupling H2 production to oxidation of reduced ferredoxin with generation of a sodium ion gradient. MBH is encoded by a 14-gene operon with both hydrogenase and Na(+)/H(+) antiporter modules. Herein a His-tagged MBH was expressed in P. furiosus and the detergent-solubilized complex purified under anaerobic conditions by affinity chromatography. Purified MBH contains all 14 subunits by electrophoretic analysis (13 subunits were also identified by mass spectrometry) and had a measured iron:nickel ratio of 15:1, resembling the predicted value of 13:1. The as-purified enzyme exhibited a rhombic EPR signal characteristic of the ready nickel-boron state. The purified and membrane-bound forms of MBH both preferentially evolved H2 with the physiological donor (reduced ferredoxin) as well as with standard dyes. The O2 sensitivities of the two forms were similar (half-lives of ∼ 15 h in air), but the purified enzyme was more thermolabile (half-lives at 90 °C of 1 and 25 h, respectively). Structural analysis of purified MBH by small angle x-ray scattering indicated a Z-shaped structure with a mass of 310 kDa, resembling the predicted value (298 kDa). The angle x-ray scattering analyses reinforce and extend the conserved sequence relationships of group 4 enzymes and complex I (NADH quinone oxidoreductase). This is the first report on the properties of a solubilized form of an intact respiratory MBH complex that is proposed to evolve H2 and pump Na(+) ions.

Synthesis, Structures, and Properties of Four Novel HgII Complexes Based on Pyridine Acylamide Ligands

In this work we synthesised four new pyridine acylamide complexes [HgI2(L1)] (1) and (2), [HgI2(L2)2] (3), and [HgI2(L3)]n (4) (L1 = N,N′-bis(3-pyridylmethyl)benzene-1,4-dicarboxamide, L2 = N4,N4′-bis(pyridin-3-yl)-[1,1′-biphenyl]-4,4′-dicarboxamide, L3 = N1,N3-bis(pyridin-3-ylmethyl)isophthalamide) by solvo(hydro)thermal reaction. Compounds 1 and 2 are supramolecular isomers prepared via variation of the reaction solvent, in which the HgII centres are bridged by L1 ligands to form one-dimensional (1D) helical chain or 1D meso-helical chain, respectively. Careful inspection of the structures reveal that formation of the isomers are mainly induced by the distinct configuration of L1 ligand and slight differences in coordination geometry of the HgII ions. Complex 3 shows a novel Z-shaped zero-dimensional structure with a L2–HgI2–L2–HgI2–L2 arrangement. In complex 4, flexible L3 ligands link HgI2 units to construct a 1D helical chain with an overall chiral structure, derived from spontaneous resolution. Luminescence properties of these four novel complexes were also explored.