Proposed Design Scheme Research Articles

Roller-combing machine for preparation of combs

In southern zone of cotton growing with insufficient moisture, one of the leading places is occupied by develop tools which simultaneously execute the technology trial of forming ridges and prepare them to display cotton. The purpose of research confirms design and the width gripper roller with elastic stems. Constructive scheme of the comb-maker with the roller-comb-makers is given. The proposed design scheme of the machine includes sequentially installed comb-makers and rollers-comb-makers. Analytic dependencies and mathematic patterns were obtained to define the width gripping roller of comb-forming machine. Theoretical and experimental studies have established that to ensure that the soil is prepared for sowing cotton on the ridges with minimum power consumption, width the gripping roller of the comb-forming machine should be at least 60 cm.

Energy-to-peak control for switched systems with PDT switching

<abstract><p>This paper investigates the issue of energy-to-peak control for continuous-time switched systems. A generalized switching signal, known as persistent dwell-time switching, is considered. Two different strategies for state-feedback controller design are proposed, using distinct Lyapunov functions and a few decoupling techniques. The critical distinction between these two strategies lies in their temporal characteristics: one is time-independent, while the other is quasi-time-dependent. Compared to the former, the latter has the potential to be less conservative. The validity of the proposed design strategies is demonstrated through an example.</p></abstract>

Trimmed-TDL-Based TDC Architecture for Time-of-Flight Measurements Tested on a Cyclone V FPGA

This paper introduces a Trimmed-Tapped-Delay-Line-based Time-to-Digital Converter (TTDL-TDC) architecture. Unlike state-of-the-art works, where the propagation time of the TDL is roughly equivalent to the system clock period, the TDL of the proposed architecture can be shortened to use only 63% of the necessary length to propagate a clock cycle without loss of resolution. To achieve this reduction, the clock signal is propagated throughout this Trimmed TDL (TTDL), capturing its position with the rising edge of a latching signal. An encoder based on transition detectors and ones-counters modules is employed to determine the clock’s phase from the captured code in TTDL. The architecture was implemented in a Cyclone V FPGA, nevertheless, the proposed design methodology allows for migrating the design to any other FPGA device. The experimental results showed a resolution (LSB) of 5.98 ps and a overall precision of 7.6 ps. Additionally, the proposed design strategy saves hardware resources, allowing the exploration of multichannel measurement systems in low-end devices.

Adaptive compensation control for nonlinear stochastic multi‐agent systems: An event‐triggered mechanism

AbstractThis paper proposes an adaptive compensation control algorithm for solving the actuator failures problem of nonlinear stochastic multi‐agent systems (MASs) under the directed communication topology. It should be emphasized that the coexistence of unknown nonlinearities, stochastic perturbations and actuator failures makes the implementation of control protocol very difficult and extremely challenging. To achieve the control objective, fuzzy logic systems (FLSs) are first employed to deal with the unknown nonlinearities of each agent. Then, the threshold‐based event‐triggered mechanism is further considered to reduce the communication burden of the system in the case of limited communication resources. Moreover, the issue of “explosion of complexity” is solved by using dynamic surface control (DSC) technique in the process of backstepping design. With these efforts, the actuator failures are circumvented and the outputs of the followers converge to the convex hull spanned by the multiple leaders' outputs. Finally, the simulation results of multiple single‐link robots show the validity of the proposed design scheme.

Design of metasurfaces with decoupled amplitude and phase response for spatial light modulation.

Spatial light modulators based on metasurfaces have attracted great attention due to their abilities of amplitude and phase modulation. However, the traditional one degree of freedom (1-DOF) tunable metasurfaces are limited by incomplete phase coverage and coupled amplitude and phase modulation. Here, we propose an optimization method for 2-DOF tunable metasurfaces within the framework of temporal coupled mode theory. As a validation of the proposed method, we present a germanium antimony tellurium (GST)-alloy-based 2-DOF tunable reflective metasurface. Full-wave simulation shows that independent modulation of amplitude and phase is realized with full phase coverage and amplitude range from 0 to 0.55. Our proposed design scheme for a 2-DOF tunable metasurface may facilitate the development of high-performance metasurface devices.

Low Frequency Waterborne Sound Insulation Based on Sandwich Panels With Quasi-Zero-Stiffness Truss Core

Abstract Due to the negative correlation between pressure resistance and waterborne sound insulation, low-impedance soundproof materials can hardly work in deep water. Here, we propose a new mechanism to circumvent this problem by employing a sandwich panel with designed dynamics quasi-zero-stiffness (QZS) truss cores. The latticed cores are made of programable curved beams, whose shape is carefully designed to meet the demand of both high-pressure resistance and dynamics QZS. An analytical model is developed to evaluate sound transmission of such panel. It is shown that the low-frequency sound insulation performance of the customized panel increases with the hydrostatic pressure and reaches its maximum when the QZS state is triggered. The effective pressure range of the proposed sandwich panel can be further programed by stacking QZS beam lattices of different static load plateaus. The proposed design strategy stems solely from the structural geometry of the curved beams and is therefore materials-insensitive. The linear/inverse relationships between static loading feature and characteristic mechanical properties/geometrical parameters, and the stacking arrangement of lattice bring out the programability of the panel’s bearing capacity. The design strategy, together with the established database, provides a feasible approach for underwater sound insulation of equipment subjected to elevated pressures.

Targeted modal response control of structures with inerter-based vibration absorbers considering modal interaction effects

Inerter-based vibration absorbers (IVAs) have been widely studied for the vibration control of multi-degree-of-freedom (MDOF) structures. Common analytical optimization strategies of IVAs for controlling the modal response of a specific mode neglect the contributions from non-resonant modes (denoted as modal interaction effects hereafter), which could weaken the validity of the optimum solution, while directly employing numerical search methods usually implies expensive computational costs in repeatedly evaluating control objectives under different sets of IVA parameters. To aim at both accuracy and efficiency of optimum design solution of IVAs for targeted modal response control, the Sherman-Morrison inversion (SMI) is exploited in this paper to derive explicit expressions of frequency response functions (FRFs) of IVA-controlled structures based on an MDOF model established in modal coordinates. In this way, the non-zero off-diagonal elements and precise expressions of diagonal elements in the FRF matrix are explicitly incorporated in the design process, with full account for modal interaction effects. The SMI is further implemented to calculate the FRF matrix of structures controlled by multi-IVA (MIVA) in an iterative manner, and subsequently, design strategies for targeted modal control using (M)IVA are proposed with particular focuses on wind-resistance and seismic design. Based on a high-rise building taken as the case study, the accuracy and efficiency in calculating the FRF matrix are quantitively assessed by Monte Carlo simulations. Two design examples, i.e., using a single tuned inerter damper (TID) for wind-resistance design and using a multi-TID for seismic design, are presented to validate the precision and efficiency of proposed design strategies. The results indicate that modal interaction effects are increasingly important for the design of (M)IVAs having larger inertance or being tuned to higher modes.

Design of Composite Joint with Precast Bolted Shear Connectors for The Fabricated Structure

Because of the serious impact on the seismic performance, the joint connection form becomes a critical problem in the prefabricated building. Built on the dry connection, this paper proposes a detachable and recyclable bolt-steel plate connection design for the fabricated structure. Compared to the cast-in-situ method, the biggest advantage of the proposed design scheme lies in convenient construction. The construction process shows that the joint devices both are detachable and recyclable. Adopting a supported beam, the proposed form is simulated with the finite element method (FEM). The deformation results verify the effectiveness of the proposed connection design. The work provides a novel idea for further test research on the fabricated structure.

Experimental and numerical studies on the compression responses of novel mixed lattice structures

Mechanical lattice structures have recently attracted the attention from researchers due to their lightweight and enhanced mechanical properties. Despite the dual-phase lattices have more better energy absorption capability and compression performance than the single pure lattice, limited mechanical properties still exist in the dual-phase lattices. In this work, a novel mixed structural design strategy is proposed and the specimens are fabricated by selective laser sintering. Both experimental test and numerical evaluation are conducted to validate the rationality of the proposed design strategy. Results indicate that the novel mixed lattice can achieve the higher energy absorption and lightweight in comparison with the pure and dual-phase lattice. The energy absorption efficiency could be adjusted by altering the types or sizes of basic unit cells. The proposed analytical methods can well predict the plateau stress of the mixed lattices with various geometrical dimensions. The finding of this work contributes to the designs of lattice structures with energy absorption and superior mechanical properties.

Rational design strategies for nonconventional luminogens with efficient and tunable emission in dilute solution

The design and synthesis of organic nonconventional luminescent (NL) materials with efficient emission have attracted significant attention. However, these materials usually suffer from the fact of low photoluminescent quantum efficiency (Φ), poor tunability of emission wavelength, and non-luminescence in dilute solution, limiting their further application. Herein, rational molecular design strategies for NL compounds with efficient and tunable emission in dilute solution were presented via theoretical calculation and practical verification. Firstly, increasing the ratio of π → π* transition in the excited state to suppress the n → π* transition, inhibit intersystem crossing, and avoid the generation of triplet excitons which can be easily quenched by water or oxygen. Secondly, introducing strong intramolecular hydrogen bonds to suppress intramolecular rotation and inhibit non-radiative transitions. Besides, D-π-A structure can effectively adjust the luminescence color. Based on the proposed design strategies, two novel compounds named LJ-1 and LJ-2 were synthesized, both compounds can emit bright green fluorescence in dilute solution with Φ of up to 59.8 %, and their photophysical properties are pH-dependent. The results showed that pH had a great impact on the strength of intramolecular hydrogen bonds and the degree of conjugation. For example, the emission wavelength of LJ-1 exhibited red-shift as the increase of pH value. Furthermore, LJ-1 can be used for visual detection of Ag+ in water solution in naked eye and the precise localization of lysosomes. We believe that our work will greatly broaden the application range of nonconventional luminogenic compounds in future.

Multi-modal seismic control design for multi-storey buildings using cross-layer installed cable-bracing inerter systems: Part 1 theoretical treatment

Many attempts have been made to improve the performance of buildings subjected to ground motions with a novel mechanic element, known as an inerter, thereby giving buildings more stability. Recently, a characteristic of the inerter system on controlling the target mode, called the target mode control effect, has been discovered. Considering the prospects of target mode control effect on controlling those buildings affected by multi-modal responses, in this study, cross-layer installed cable-bracing inerter systems (CICBISs) will be used for the multi-modal seismic control. For releasing the end torsion constraints demand of the ball-screw inerter and simplifying the CICBIS's realization, a self-balanced inerter is proposed. A multi-modal seismic control design strategy is proposed to determine the optimal parameters of CICBISs. The equivalent mass with a physical meaning of the multi-storey building with a CICBIS is proposed to quantify the control efficiency of the CICBIS's placement and determine the installation placement of CICBISs directly. A 20-story benchmark building is used to validate the design strategy. The results show that the CICBISs tuned to multi-modes through applying the proposed design strategy can simultaneously focus on controlling multiple target modes. Moreover, it is proved that under the same constraint on each device's control force, the designed CICBISs obtain a higher efficiency on suppressing seismic responses than those CICBISs for single-modal seismic control we proposed in the past and cross-three-layer installed tuned viscous mass dampers. Further sections of the study, including device tests on a self-balanced inerter's prototype and shake table tests on corresponding CIBCIS, will be offered in the following companion paper: Part 2 Experimental treatment.

A deep learning approach for inverse design of gradient mechanical metamaterials

Mechanical metamaterials with unique micro-architectures possess excellent physical properties in terms of stiffness, toughness, vibration isolation, and thermal expansion. Meanwhile, meta-structures in organisms or geography operate efficiently under complex service conditions thanks to their heterogeneous and gradient distribution of naturally evolved micro-architectures that are difficult to obtain by forward design. In this paper a multi-network deep learning system that satisfies the different design property requirements of microstructures is proposed, and the network predicts the configuration with 99.09% accuracy. The analogy between color space and mechanical parameter space is used to transform parametric design into pixel matching. The microstructures are prepared by AM (additive manufacturing) and their properties are verified by DIC (Digital Image Correlation) experiments (the property error of the structures was less than 2%). Multiscale inverse design of multifunctional and gradient mechanical metamaterials is realized, with special attention payed to the automatic customization of biomimetic structures. The design flow takes only 2 s and the geometric connectivity between microstructure units is considered to ensure compatibility between adjacent microstructures for AM. The proposed design strategy accelerates the emergence of high-performance structures, and provides a reference for topology optimization design of mechanical metamaterials.

A Conceptual Design and Optimization Approach for Distributed Electric Propulsion eVTOL Aircraft Based on Ducted-Fan Wing Unit

The distributed electric propulsion (DEP) eVTOL aircraft has gained rising interest for its promising potential in high-speed cruise compared with conventional tilt-rotor configuration. The aerodynamic interference of the DEP units and wing could become more complicated with a variable thrust in multiple flight conditions. Thus, it requires considerable effort to trade off in the whole design process. Aimed at improving the design efficiency in iteration cycling of a ducted-fan DEP eVTOL aircraft, a conceptual design and optimization approach is proposed in this paper regarding the single-ducted fan and its surrounding wing section as the basic unit. The optimization of the ducted-fan wing (DFW) unit is targeted at improving both hover and cruise efficiencies. After the verification of the span independence of the lift-and-drag coefficients of the DFW unit, a novel DEP eVTOL aircraft conceptual design approach is established based on the vertical meridional plane DFW unit performance analysis. In the following case study, the optimized DFW unit and the conceptual method are applied on a canard configuration, achieving 720 km/h maximum speed, a hovering efficiency of 76.3%, and a 10.7 cruise lift-to-drag ratio. The remarkable performance and concise workflow in the case study both demonstrated the applicability and effectiveness of the proposed design schemes for DEP eVTOL aircraft.

Highly stretchable and strong poly (vinyl alcohol)-based hydrogel for reprogrammable actuator applications

Hydrogel is considered as a suitable choice for fabrication of actuators because of its similarity to biological tissues and multi-stimuli responsiveness. However, it is necessary to address the limit resulted from the traditional bilayer structure that leads to interface issue or permanent gradient structure that leads to unchangeable deformation mode. Herein, a highly-stretchable and reprogrammable PVA-based hydrogel actuator is reported. The actuator was fabricated through a freezing-thawing treatment of the blend of PVA, mono (9-anthracene methyl) succinate grafted PVA (PVA-SA-AN), tannic acid (TA) and cetyltrimethyl-ammonium bromide (CTAB) followed with UV irradiation. According to the scheme, PVA forms the hydrogel substrate and helps disperse the hydrophobic PVA-SA-AN into the hydrogel. TA forms hydrogen bonds with PVA and PVA-SA-AN, providing enhancement to the mechanical properties of the hydrogel. CTAB further disperses the anthracene groups so that the UV-induced reversible dimerization/cleavage can endow the hydrogel with the function of water-driven actuation as well as reversible programmability. The improved mechanical properties and the reprogrammable actuation performance are demonstrated. We believe that the proposed design strategy can provide a facile and low-cost way to develop high-performance reprogrammable hydrogel actuators.

Real‐time control design and implementation of ball balancer system based on machine learning and machine vision

SummaryThis article addresses a hybrid pseudo‐PD/machine learning controller algorithm to improve the stabilization and trajectory tracking of the ball on the plate system (BOPS). The proposed controller design depends on a machine learning algorithm that detect the angle of the servo motor required to correct the position of the ball on the plate also the parameters of the PD controller is changed online using the fuzzy logic to enhance the performance of the trajectory and point tracking of the system. This article offers three different machine learning techniques for predicting servo motor angle that obtain higher accuracies of 99.95%, 99.908%, and 99.998% for support vector regression, decision tree regression, and random forest regression, respectively. The proposed scheme has greatly improved the system's settling time and overshoot, according to simulation and practical results. The Lagrangian formulation may be used to obtain the mathematical formulation, and a practical identification experiment can be used to determine the servo motor parameter. Simulation and practical results on a BOPS dynamic model are both demonstrated to justify the validation of the proposed design scheme. The experimental practical results justify the feasibility and effectiveness of the proposed controller design strategy.

Bioinspired inverse enamel-like columnar composites reproducing the mechanical properties and tribological performance of human enamel

The development of high-performance dental materials that mimic human enamel is urgently required for clinical applications, but remains a key challenge. Herein, we present a biomimetic design strategy for creating inverse enamel-like columnar composites that replicate the mechanical properties and tribological performance of the natural enamel. Inverse to the enamel consisting of hard rods and surrounding relatively soft inter-rod, the composites are assembled from a cellular-structured ceramic scaffold and resin columns. This architecture helps to avoid dramatic stiffness and hardness decreases due to the presence of flexible substances and provides an elegant combination of mechanical properties that strikingly resemble that of natural enamel. Consequently, the inverse enamel-like columnar composites have encouraging tribological performance characterized by an enamel-matched coefficient of friction and wear rate, as well as low abrasive potential to opposing natural teeth, demonstrating great promise for next-generation dental restorations/replacements and other applications. More importantly, the proposed design strategy can be extended to other biological prototypes, thus facilitating the development of various high-performance functional materials.

"Conical" Frustum Multi-Beam Phased Arrays for Air Traffic Control Radars.

The design of conical frustum phased array antennas for air traffic control (ATC) radar systems is addressed. The array architecture, which is controlled by a fully digital beam-forming (DBF) network, is composed by a set of equal vertical modules. Each module consists of a linear sparse array that generates on receive multiple instantaneous beams pointing along different directions in elevation. To reach the best trade-off between the antenna complexity (i.e., minimum number of array elements and/or radio frequency components) and radiation performance (i.e., matching a set of reference patterns), the synthesis problem is formulated in the Compressive Sampling (CS) framework. Then, the positions of the array elements and the complex excitations for generating each single beam are jointly determined through a customized version of the Bayesian CS (BCS) tool. Representative numerical results, concerned with ideal as well as real antenna models, are reported both to validate the proposed design strategy and to assess the effectiveness of the synthesized modular sparse array architecture also in comparison with conventional arrays with uniformly-spaced elements.

A 280 GHz 30 GHz Bandwidth Cascaded Amplifier Using Flexible Interstage Matching Strategy in 130 nm SiGe Technology

This paper presents a 280 GHz amplifier design strategy for a robust multistage amplifier in a sub-Terahertz (sub-THz) regime in 130 nm SiGe technology. The presented 280 GHz amplifier consists of 14 stages of the cascaded common emitter (CE) amplifier which offers a compact and improved-noise design due to the absence of the area-expensive and lossy baluns at such high frequencies. The interstage-matching network was flexibly constructed with two separate resonant tanks using metal–insulator–metal (MIM) capacitors and microstrip transmission lines (MSTLs) between each stage. The measured amplifier achieved a peak power gain of 10.9 dB at 283 GHz and a 3 dB gain of bandwidth of 30 GHz between 270 and 300 GHz. The peak output power of the amplifier was 0.8 dBm with an output of 1 dB gain compression point (OP1dB) of −3.6 dBm in simulation. The 14-stage amplifier consumes an area of 0.213 mm2, including all the pads. With the proposed interstage matching approach, a well-balanced 280 GHz amplifier has been demonstrated. The proposed design strategy is widely applicable to sub-THz receivers for future wireless communication systems.

Design and Optimization of a Micron-Scale Magnetoelectric Antenna Based on Acoustic Excitation.

The development of antenna miniaturization technology is limited by the principle of electromagnetic radiation. In this paper, the structure size of the antenna is reduced by nearly two orders of magnitude by using Acoustic excitation instead of electromagnetic radiation. For this magnetoelectric (ME) antenna, the design, simulation and experiment were introduced. Firstly, the basic design theory of magnetoelectric antennas has been refined on a Maxwell’s equations basis, and the structure of the ME antenna is designed by using the Mason equivalent circuit model. The influence mechanism of structure on antenna performance is studied by model simulation. In order to verify the correctness of the proposed design scheme, an antenna sample operating at 2.45 GHz was fabricated and tested. The gain measured is −15.59 dB, which is better than the latest research that has been reported so far. Therefore, the ME antenna is expected to provide an effective new scheme for antenna miniaturization technology.

Software and hardware co-design and implementation of intelligent optimization algorithms

In order to improve the operating efficiency of the algorithm, some intelligent optimization algorithms are considered to be implemented on hardware. However, the existing design scheme has the problem of poor versatility. Therefore, this paper proposes a general software–hardware co-design scheme of intelligent optimization algorithms. In the design scheme, the initialization module and fitness module of the algorithm are deployed on the Advanced RISC Machines (ARM) for execution to increase the flexibility of the program. The update module of the algorithm is deployed on the Field Programmable Gate Array (FPGA) for execution to realize the hardware acceleration. The data between ARM and FPGA is transferred through Advanced eXtensible Interface (AXI) bus. In this paper, the PSO, BA, WOA, GWO, CMAES and EO algorithms are implemented with the proposed design scheme. And the six algorithms are tested on thirteen benchmark functions of different types. The experimental results prove the feasibility of the design scheme. In addition, by comparing with software and other implementation methods in execution time, resource occupancy and convergence, the effectiveness and superiority of the proposed scheme are proved.