Proposed Design Method Research Articles

Optimized Multiloop Fractional-Order Controller for Regulating Frequency in Diverse-Sourced Vehicle-to-Grid Power Systems

A reduced power system’s inertia represents a big issue for high penetration levels of renewable generation sources. Recently, load frequency controllers (LFCs) and their design have become crucial factors for stability and supply reliability. Thence, a new optimized multiloop fractional LFC scheme is provided in this paper. The proposed multiloop LFC scheme presents a two-degree-of-freedom (2DOF) structure using the tilt–integral–derivatives with filter (TIDN) in the first stage and the tilt–derivative with filter (TDN) in the second stage. The employment of two different loops achieves better disturbance rejection capability using the proposed 2DOF TIDN-TDN controller. The proposed 2DOF TIDN-TDN method is optimally designed using the recent powerful marine predator optimizer algorithm (MPA). The proposed design method eliminates the need for precise modeling of power systems, complex control design theories, and complex disturbance observers and filter circuits. A multisourced two-area interlinked power grid is employed as a case study in this paper by incorporating renewable generation with multifunctionality electric vehicle (EV) control and contribution within the vehicle-to-grid (V2G) concept. The proposed 2DOF TIDN-TDN LFC is compared with feature-related LFCs from the literature, such as TID, FOTID, and TID-FOPIDN controllers. Better mitigated frequency and tie-line power fluctuations, faster response, lower overshot/undershot values, and shorter settling time are the proven features of the proposed 2DOF TIDN-TDN LFC method.

On error-driven nonlinear ESO based control design with application to air–fuel ratio control of engines

In this paper, the tracking control problem of the uncertain control system is studied in the frame of uncertainties estimation and compensation. To eliminate the influence of external disturbances and internal uncertainties on the control system, the error-driven nonlinear extended state observer (EDN-ESO), whose gain is set as an increasing function with respect to the absolute value of estimation error of the system output, is proposed to improve the estimation performance for the “total disturbance”. Next, both the estimation error of proposed ESO and the tracking error of system output are proven to be bounded by selecting the lower bound and variation range of ESO’s bandwidth. Moreover, the convergence of the estimation error as well as the tracking error to zero is proven under certain conditions. Finally, the proposed design method is applied to the air–fuel ratio control system of gasoline engines, and the experimental results show that the proposed EDN-ESO can effectively adjust the observer gain, so as to enhance the tracking performance.

Forming process chain for manufacturing complex conical-section profiled rings: On a co-design method

The final quality of complex conical-section rings depends on co-design of multiple processes in forming process chain. In this study, for a complex aeroengine casing ring with a large slope and a flange on its end, a co-design method of the forming process chain is put forward towards the objective of precision forming, which not only proposes a standard process route composed of multiple processes of upsetting, punching, rectangular ring rolling, loose tooling forging and profiled ring rolling, but also presents co-design methods of dies and blanks for all the processes. For profiled ring rolling, a design method of preformed blank that makes the blank and the target conical-section ring have the same axial volume distribution is proposed. By the method, the axial metal redistribution during the process can be alleviated greatly thus improving the forming stability and precision of the ring. Based on the geometric features of designed preformed blank, design methods of blanks and dies for loose tolling forging, rectangular ring rolling, punching and upsetting are proposed sequentially. In view of the key roles of loose tooling forging (manufacturing the preformed blank) and profiled ring rolling on the final quality of the conical ring parts, inherited FE simulations for these two processes are performed to verify the proposed design methods and determine appropriate design parameter. It is demonstrated that the proposed design method has significant advantages in improving forming precision. Besides, a suggestive value 1.5 of the rolling ratio for profiled ring rolling (a key design parameter) is given based on comprehensive consideration of multiple indicators such as ring roundness, deformation uniformity and forming load. The corresponding industrial experiments performed illustrate that a high forming precision of the conical-section aeroengine casing ring is achieved.

Seismic design and performance evaluation of hybrid braced frames having buckling-restrained braces and self-centering viscous energy-dissipative braces

Hybrid braced frames (HBFs) emerge as an innovative seismic-resilient system, synergizing the strengths of buckling-restrained braces (BRBs) and self-centering viscous energy-dissipative braces (SCVDBs). This novel system has the potential to simultaneously manage three key seismic demand parameters: peak inter-story drift (PID), residual inter-story drift (RID), and peak absolute floor acceleration (PFA). Nevertheless, a dedicated seismic design method for HBFs is yet to be developed. This research proposes a performance-based seismic design (PBSD) method specifically tailored for HBFs. The method's core relies on energy decoupling in the HBFs using a proposed energy distribution factor (η). To validate the proposed design method, sets of 4-, 8-, and 12-story braced frames are designed using varied η. A comprehensive seismic performance evaluation is conducted, utilizing nonlinear static and nonlinear time-history analyses. The findings indicate that the HBFs, designed utilizing different values of η, consistently meet predefined performance objectives. Within the scope of this study, the η value of 0.5 is shown to be optimal, enhancing the structural resilience of HBFs against PIDs and PFAs while exhibiting excellent self-centering performance comparable to the self-centering viscous energy-dissipative braced frame (SCVDF). Additionally, the HBFs demonstrate superior control over PFA compared to pure buckling-restrained braced frame (BRBF) and SCVDF.

A Reconstructed Singular Return Ratio Matrix for Optimizing Design of the PLL in Grid-Connected Inverters

Phase-locked loop (PLL) is essential for the grid-connected inverter to ensure grid synchronization. Since the PLL introduces an negative-resistive admittance to be in parallel with the original inverter output admittance, it poses an instability risk for the grid-connected inverter under weak grid. The system stability can be evaluated by the return ratio matrix, which is the ratio of the inverter output admittance to the grid admittance. Due to the non-singular and non-diagonal properties of this matrix, its eigenvalues are irrational functions, leading to inconvenience of stability analysis and PLL parameters design. To address this issue, this paper reconstructs the return ratio matrix to make it singular. Thus, the eigenvalues become simpler, including a zero eigenvalue and a non-zero eigenvalue. Based on the non-zero eigenvalue, the relation between the gain margin and the PLL parameters is established, and an optimizing design method of the PLL parameters is proposed to achieve system stability and satisfactory PLL dynamic response. Finally, experimental results from a 10-kVA prototype of three-phase grid-connected inverter are provided to verify the validity of the proposed design method.

A unidirectional secondary sound source for local active noise control in enclosures

Directional secondary sources are beneficial for local active noise control in cabins with multiple seats. In this paper, a method of designing a unidirectional compound sound source composed of two units is introduced. A prototype was implemented using two closed-box speakers and an analog circuit, and the directivity of the compound source was measured in the anechoic chamber to verify the effectiveness of the proposed design method. Furthermore, the sound radiation characteristics of the compound sound source in a car cabin are reported and analyzed. The average sound pressure level at the driver's seat and rear seats is reduced by over 3.5 dB and 8.3 dB respectively in the frequency range from 125 Hz and 500 Hz when a single loudspeaker box located at the front passenger's seat is replaced by the compound sound source.

Design and Experiment of a Reconfigurable Bypass Downlink Surface Equipment for Transmitting the Surface Information to Deep Well

Abstract: In order to achieve the transmission of the control information from the surface to the downhole in the deep well during drilling, a design method of a new downlink surface equipment for generating negative pulse signals is presented in this paper. The equipment uses adjustable throttle control valve and pressure drop module (PDM) to realize bypass flow control. The PDM uses multistage variable nozzles to reduce drilling fluid pressure and meet drilling requirements under different pressure and flow rates. Design theory of the downlink surface equipment is established, and a specific design instance is given according to actual drilling conditions. Both laboratory and field experimental results verify the correctness of the proposed design method. The research results show that the design equipment can meet the needs of the transmission of the surface information, and the downlink transmission rate can reach at least one-bit data per 8 sec. The maximum pressure drop is realized by the PDM and the pressure drop at the control valve will be reduced according to drilling demand, the fluid velocity in the equipment is reduced as much as possible, the erosion of the drilling fluid to the equipment is reduced, and the service life can be improved effectively.

Structural Designs of Novel Deployable Polyhedral Grippers for Noncontact Capturing Missions

Abstract Deployable polyhedral grippers have attracted increasing attention for their priority in noncontact capturing missions. Enrichment of these grippers may benefit the conduction of various capturing tasks. In this paper, novel deployable polyhedral grippers are presented. A design flow is proposed for the structural designs of diverse grippers. The core problem during the construction is reducible to the structural designs and combination of multiple synchronously deployable modules. Each module, containing three faces connected by two revolute joints, can realize one-degree-of-freedom deployment. Type synthesis of synchronously deployable modules adopting different layouts of revolute joints is conducted. The mobility and kinematics of these modules are analyzed to verify the achieved motion. As examples, four deployable polyhedral grippers based on different polyhedrons and deployment diagrams are presented. The deployment performance of the prototype proves the validity of the proposed design method and exhibits the potential of these deployable polyhedral grippers for diverse capturing missions.

Refractive extended depth-of-focus lens design based on periodic power profile for presbyopia correction.

Limitations of existing diffractive multifocal designs for presbyopia correction include discrete foci and photic phenomena such as halos and glare. This study aimed to explore a methodology for developing refractive extended depth-of-focus (EDoF) lenses based on a periodic power profile. The proposed design technique employed an optical power profile that periodically alternated between far, intermediate and near distances across the pupil radius. To evaluate the lens designs, optical bench testing was conducted. The impact on visual performance was assessed using a spatial light modulator-based adaptive optics vision simulator in human subjects. Additionally, the effects of pupil size change and lens decentration on retinal image quality were examined. A comparative performance analysis was carried out against a typical diffractive trifocal design and a monofocal lens. The proposed design method was found to be effective in uniformly distributing light energy across all object distances within the desired depth of focus (DoF). While trade-offs between overall image quality and DoF still exist, the EDoF lens design, when tested in human subjects, provided a continuous DoF spanning over 2.25 D. The results also revealed that the EDoF design had a slightly higher dependence on changes in pupil size and lens decentration than the diffractive trifocal design. The proposed design method showed significant potential as an approach for developing refractive EDoF ophthalmic lenses. These lenses offer a continuous DoF but are slightly more susceptible to variations in pupil size and decentration compared with the diffractive trifocal design.

Intelligent Vehicle Inspection Tool Design Based on Freeman Chain Code for Automatic Annotation of 3D Models

Autonomous vehicle are more and more widely used in daily life, and the requirements for their safety performance are higher and higher. As a tool for testing auto parts, intelligent inspection tools are crucial to the guarantee of automobile quality. However, traditional fixture design relies on manual drawing, which is inefficient and prone to errors. To solve this problem, this research uses Freeman chain code to determine the annotation object, uses case clustering method to annotate, and uses error back propagation algorithm to realize case knowledge classification learning, and designs intelligent vehicle inspection tool design technology based on Freeman chain code 3D automatic annotation method. The experimental results show that the geometric feature matching results are correct, and the difference in feature comparison results is significant, with a high accuracy rate. Meanwhile, the geometric similarity annotation method has a high accuracy rate, taking only 3 minutes to complete the annotation, which is 7 minutes longer than traditional manual annotation. The error backpropagation algorithm can accurately achieve feature classification, and the design time of size chain inspection tool deformation design is reduced by 214 minutes compared to manual reverse deformation design, significantly improving design efficiency. In summary, the proposed design method for automotive inspection tools can achieve automatic model annotation, improve design efficiency, and reduce design time.

Dynamic optimal control of flow front position in injection molding process: A control parameterization-based method

High dynamic and precise control of process variables within permissible limits is the key to high product quality in the injection molding industry. Among these variables, the injection flow rate of molten polymer is particularly significant. In this paper, an effective optimal open-loop and state feedback controller design method is designed to realize the optimal tracking control of the melt polymer flow front position flow of melt polymer fluid during injection molding. To this end, the dynamic model of the filling process is firstly established, taking into account the nonlinearity of hydraulic control system and the effect of molten polymer flow on the dynamics of the injection ram, and then the dynamic optimal tracking control problem of flow front position of molten polymer in injection molding machine is proposed. Then, an open-loop controller and a multi-level feedback control law are well designed, wherein the control signal and the control feedback kernels are parameterized by control parameterization. The controller design problems are transformed into sequential optimal parameter decision problems. The explicit expressions of the gradient information of the objective function and constraints on the parameters of the decision variables are solved by using the state sensitivity equation analysis method, and the gradient information is combined with the nonlinear programming algorithm to solve the optimization problems efficiently. Finally, the viability and effectiveness of the proposed design method are verified by numerical simulations.

Study on the time‐dependent interaction between surrounding rock and yielding supports in deep soft rock tunnels

AbstractAs yielding supports can deform without being damaged, the yielding principle has attracted significant attention for tunnelling in squeezing ground compared with the heavy support method. The deformation energy of surrounding rock can be managed using yielding supports that maintain the rock pressure within the bearing capacity of the supports. However, although the yielding principle has been often applied in practical scenarios, a design method for yielding supports has yet not been well developed. This study discusses interaction between the squeezing ground and yielding supports and investigates the influence of the time‐dependent behaviour of rock on the yielding supports. The yielding supports can be implemented by the movement of sliding joints of steel arches or by shortening the yielding elements inserted in shotcrete linings. The deforming process of yielding supports can be divided into three stages: elastic a, yielding, and elastic b. A three‐stage pressure‐displacement relationship of yielding supports is proposed and a method is provided for the calculation of the support stiffnesses of yielding supports in different stages. Furthermore, a unified design approach for the yielding supports is presented and the theoretical model is established after simplifying the asymmetry of problem. The analytical solution for tunnel displacement and support pressure in a tunnel supported by the yielding supports is obtained. The proposed design method for the yielding supports is successfully applied to the Saint Martin La Porte access tunnel, and the mean tunnel deformation in this tunnel is appropriately predicted by the analytical solution. Additionally, a parametric investigation is performed based on the analytical solution, and the effects of yielding path, yielding displacement, support thickness, and installation time of the yielding supports are discussed. Finally, certain highlights of the analytical model of yielding supports in this study are identified, compared with other researches, and recommendations for the design of the yielding supports are provided. The outcome of this research has potential applications in the preliminary design of deep tunnels in squeezing ground.

Predicting fracture behavior of quasi-Brittle materials using quantitatively varied geometric specimens: A design method

Fracture toughness (KIC) and tensile strength (ft) are two important parameters for describing the fracture performance of quasi-brittle materials. The accurate determination of both parameters is crucial for the safety design and stability evaluation of real engineering structures. A model and method are developed in this paper for simultaneously determining the KIC and ft for quasi-brittle materials without size effects. And using the geometric structural parameter ae as a key design parameter. This method can get KIC and ft to be obtained by fitting curves to any two sets of quantitative specimens with different geometric structures with ae ratio equal to 3. Additionally, fracture full curves and peak load prediction lines with 95% reliability are established for different fracture modes using quantitative design specimens with an ae ratio of 3. These curves and lines can accurately predict fracture behavior and peak loads of large specimens or engineering structures. The proposed design method is verified by combining experimental studies conducted by other scholars on quasi-brittle materials and the simulation results of ABAQUS software. This paper achieves the objective of accurately predicting the fracture properties of quasi-brittle material structures in the field, using quantitative laboratory specimens of various geometries.

An improved acoustic transponder system via LCCLC impedance matching network and equalization control strategy

AbstractThe underwater acoustic transducer (UAT) generates a large amount of reactive power during the operation, greatly limiting the output capability of the power amplifier. It is necessary to match the UAT and improve its load characteristics. The conventional design methods are not powerful enough to solve nonlinear or parameter‐sensitive problems, lacking enough convergence ability for the network design problem. This article proposes an optimization design method for LCCLC impedance matching network based on the improved chaos optimization algorithm and the corresponding equalization control strategy. First, the impedance model of the UAT is proposed, and then the matching principle of the LCCLC network is analyzed. Based on these, the optimization design for LCCLC network is described in detail. Then, to solve the problem of the calculation of the command signal, a control method based on the FIR filter principle is proposed. Finally, the proposed methods are verified by an experimental platform. The results show that the proposed design method and its corresponding control strategy successfully solve the matching and emission problems.

Designing sustainable high-strength self-compacting concrete with high content of supplementary cementitious materials

A sustainable and green approach to concrete mix design is fundamental for the construction sector in terms of reducing carbon dioxide ( CO 2 ) emissions and conserving non-renewable natural resources. This article proposes a novel mix design method for sustainable high-strength self-compacting concrete (HSSCC) based on rheological and mechanical properties with the aim of reducing cement content in such mixes. HSSCC mixes were designed using ground granulated blast furnace slag (GGBS) and fly ash to replace up to 40% of the cement content and tested for target compressive strengths ranging between 70 and 100 MPa. The proposed design method was numerically programmed to provide straightforward and realistic guidance in the form of design charts and verified through the design and production of sixteen HSSCC mixes consisting of varying sand-to-aggregate ratios (S/A). All mixes satisfied the self-compacting concrete criteria in the fresh state and achieved the targeted viscosity and compressive strength values. The effects of S/A and paste-to-solid (P/S) ratios on the rheological properties were evaluated. The experimental results demonstrated that the proposed mix design method could produce HSSCC with excellent fresh and mechanical characteristics while being eco-efficient with respect to CO 2 emissions and cement consumption.

Finite-Time Synchronization of Complex Networks With Privacy-Preserving

As a security issue, privacy protection has been widely valued in the security field. Based on privacy protection, the paper discusses the finite-time (FnT) synchronization of complex networks. Firstly, the FnT convergence theorem for dynamical systems is discussed. Secondly, FnT privacy protection function (PPF) is designed, the main idea of this method is to propose a FnT privacy protection function which can cover up the real state of the controlled complex network, that is, in a FnT, instead of transmitting their actual state values, the controlled network acts on the values of the design function. The designed function is continuous time-varying functions that converge to the true state in FnT. Finally, simulations mean that the proposed design method is effective.

Theoretical and experimental study on improving diaphragm compressor design for hydrogen refueling stations through use of a free moving oil piston concept

The diaphragm compressor is the essential component of a hydrogen refueling station, but the traditional design method results in low cavity volumetric efficiency and high refilling oil pressure. This study proposes a design method using a free moving oil piston to optimize the cavity volume. This method allows the cavity volume to be utilized to the maximum, and a “zero pressure” stage occurs at the end of the suction process, which greatly improves the cavity volumetric efficiency and reduces the refilling oil pressure. To further examine and verify the superiority of this method, 90 MPa and 200 MPa diaphragm compressors were designed and produced for comparison, and their simulation study was conducted simultaneously. The results demonstrate that this proposed design method can raise the cavity volumetric efficiency of the 90 MPa diaphragm compressor in the experimental case from 0.37 to 0.66. Additionally, the benefit increases with the compressor pressure. For the case of a 200 MPa diaphragm compressor, the cavity volumetric efficiency increases from 0.19 to 0.64.

Design and evaluation of a sustainable entropy-weighted and VIKOR-based method for offshore oil collecting

With the expansion of marine oil exploitation, offshore oil leakage has become an urgent problem that cannot be ignored in marine ecological protection. To address the problem, this paper proposes a comprehensive design and evaluation approach aiming at the design of offshore oil collection. This approach combines the entropy weight and VIKOR method with three principles of sustainable design. Specifically, to establish the evaluation model, this paper transforms these principles of sustainability into three aspects of practicality, economy, and environmental protection, thus constructing a multi-level evaluation index system. Subsequently, entropy weights are then used to decline the one's own element in the decision maker's weights. Besides this, the VIKOR method is applied to acquire the optimal ranking of design alternatives for offshore oil collection to choose the optimal product design strategy. According to the obtained experimental results, the proposed design method combining the entropy weight and the VIKOR method is feasible and reasonable. To be exact, it improves the comprehensive index of the product in the design concept stage by over 20%, and it effectively optimizes the resource allocation of the design process.

Improved design shear method of the bolted cold-formed steel clip-angle for serviceability

This paper presents an experimental investigation on the three-bolted clip-angle (CA) connector under direct shear load. A total of 48 clip-angle connection tests were carried out with 27 different clip-angle configurations by varying the thickness, width and depth of the clip-angle. The present experimental results and the data from literature indicates that the existing design methods for the service limit state design of the clip-angle are inefficient. The present investigation proposes a novel and efficient design method for the service limit state after calibration against test data, for the low-grade steel clip-angle (fy=271MPa to 307 MPa) from the present research work and for the higher grade steel (fy=375MPa to 550 MPa) from the literature data. Hence the proposed design method has wider steel grade application from fy=271MPa to 550 MPa. Parametric studies were performed to evaluate the influence of the geometric variables on the service shear strength of the three bolted clip-angle. The proposed design method was also applied to the welded clip-angle configuration in the literature and corresponding design equations were developed. In addition, a comparative study between the present three-bolted and most recent welded clip-angle connection was conducted which indicated that the three-bolted clip-angle configuration has higher stiffness than that of the welded configuration. Reliability studies were performed and relevant design factors were determined according to the LRFD, LSD and ASD methods.

Parallel-coupled bandpass filters with directly coupled input and output resonators

A novel method for modifying input and output coupling in the parallel-coupled bandpass filters, which allows for direct connection of source and load to the outer resonators, is proposed. In the filter modification a coupled-resonator approach is utilized, which allows one for calculating both the impedance of the introduced new quarter-wave section and the necessary coupling modification of the first and second resonators. The proposed filter modification allows for realization of wider bandwidth filters by removing the necessity of narrow gap realization. Further the following gap in the filter is also enhanced, what helps in wide band filter realization. The presented theoretical approach has been confirmed by theoretically calculated responses of three- and seven-resonator filters. The theoretically investigated filter modification has been confirmed with the experiment in which a seven-resonator modified bandpass filter has been fabricated and measured. The presented measurement results confirm the theoretical predictions and prove the proposed design method.