Simple Design Procedure Research Articles

Self-triggered consensus resilient control for multi-agent systems against sensor deception attacks based on a single parameter learning method

This paper presents a self-triggered consensus resilient control method for nonlinear multi-agent systems (MASs) under sensor deception attacks. A single parameter learning method is integrated into backstepping technique to simplify design procedure. The neural networks are utilized to compensate for unknown dynamics of the MASs. Moreover, a self-triggered mechanism is presented for MASs to refrain from continuously monitoring triggering conditions and conserve communication resources. The designed controller can resist sensor deception attacks and guarantee that all signals of the MASs are uniformly bounded. An expository simulation example reveals the virtue of the presented method.

Serviceability limit state of incrementally launched steel bridge I-girders

Bridge girders are subjected to repeated patch loading during incremental launching (i.e. travelling over supports). Plastic deformations are likely to occur in the girder already at the first patch loading. They influence the girder’s structural response and bring about a decrease in the ultimate resistance at subsequent patch loadings. This problem is analysed in the present paper through the serviceability limit state (SLS) of incrementally launched bridge I-girders (ILBGs). The SLS of ILBGs is a current problem since only a few studies, with contrasting conclusions and certain limitations, have been recognised in the literature. Research is limited on plate girders without longitudinal stiffeners made of structural steel. Flat slide-type launching shoes are considered in this paper.The serviceability requirement (repeatable behaviour of ILBGs) and criterion (that effective membrane strains should remain in the elastic range) are adopted from the literature. So, the serviceability resistance is adopted as a load at the start of the effective membrane plastic strains in the girder. In order to propose a practical and simple SLS design procedure, the serviceability resistance is normalised against the ultimate resistance, so a serviceability correction factor (ksls) is defined. The paper presents a parametric numerical analysis of the factor (ksls). A finite element model previously developed and validated by the author is employed to simulate a nonlinear response of patch-loaded girders. The parametric study includes 599 girders. ksls is inversely proportional to the web thickness and directly proportional to the flange thickness and the yield strength of the steel material. The load length, web depth and flange width do not influence ksls. The influence of the spacing between transverse stiffeners on ksls is negligible. Finally, by regression analysis of the results of parametric study, an original and reliable serviceability correction factor is proposed as the main objective of the research. The range when the SLS of ILBGs should be checked is also defined.

Grid voltage sensorless control of a single‐phase shunt hybrid active power filter

AbstractHere, a grid voltage sensorless control of an LCL‐filtered LC‐tuned single‐phase shunt hybrid active power filter (HAPF) is proposed, which offers high‐quality harmonic current compensation with low hardware requirements. An estimation algorithm replaces the grid voltage sensor and associated circuitry to reduce the size and cost. This paper presents a straightforward and accurate modelling of the suggested structure and its filtering characteristics, followed by a comprehensive yet simple parameter design procedure. An inherent damping technique that uses digital delay rather than virtual or physical damping resistors eliminates the need for additional sensors or extra power losses. As part of the design, a high‐quality reference current is generated for the filter, which is then effectively tracked using a proportional controller with sufficient bandwidth and stability margin. An experimental prototype is implemented to verify the theoretical results, and several steady‐state and transient waveforms are reported to demonstrate the superior performance of the HAPF.

Cyclic performance of non‐ductile reinforced concrete columns retrofitted by partial steel plate jacketing: Experiment and numerical analysis

AbstractThis paper investigates the strengthening of non‐ductile reinforced concrete (RC) columns using partial steel‐plate jacketing to enhance ductile capacity. Quasi‐static cyclic loading tests were conducted on three rectangular RC columns with varying shear‐span‐to‐depth ratios, evaluating the effectiveness of steel‐plate jacketing. Results show improved ductile flexural response, high drift capacity, and maintained gravity‐loading capacity under high lateral displacements. A numerical investigation, adopting a multi‐spring fiber section model, predicted cyclic lateral strength, drift ratio, and failure mode, accurately simulating reinforcement behavior and capturing the shear‐strength enhancement due to steel‐plate jacketing. Numerical results demonstrated good agreement with experimental findings. Based on these outcomes, a simple design procedure for retrofitted concrete columns, applicable to design engineers, has been developed and reported in this paper. This study contributes valuable insights into the practical applications of steel‐plate jacketing for non‐ductile RC column retrofitting, offering a comprehensive approach to predicting their seismic performance.

Seismic performance assessment and design procedure of base-isolated bridges with lead-rubber-bearing and negative stiffness springs (LRB-NS)

This study proposed a straightforward and simplified design procedure for the base-isolated highway bridges with LRB and negative stiffness springs (LRB-NS) device. Compared with the traditional LRB-isolated system, the proposed LRB-NS device contains dual-functionality: (a) alleviate the nonlinearity and damage in piers during slight-to-moderate earthquakes; (b) control the excessive bearing deformation and prevent failure during catastrophic excitations. Therefore, this device effectively improves the post-earthquake function and seismic resilience of bridge systems, and facilitate the rescue operations, since bridge can allow the passage of urgent vehicles with minimal repair. With incremental dynamic analysis (IDA) accounting for the record-to-record variability, the LRB-NS device is shown with dual-functionality as designed and better seismic performance than LRB, subjected to all of far-field (FF), near-fault no-pulse (NFNP), and near-fault pulse-type (NFPT) motions. Additionally, the influence of three kernel parameters, i.e., target period ratio sy_LRB-NS, initial spring length l, and critical deformation ucr, is also investigated in detail, concerning both the structural properties and seismic responses. The results show that increasing sy_LRB-NS and l both benefits the dual-functionality of LRB-NS, but the efficiency reduces with the increase of these design values. While greater ucr significantly reduces column nonlinearity, the bearing deformation is increased as a result, and thus careful tradeoff should be made during practical design.

Special moment frame connections with shear-yielding haunches

Steel special moment frame connections with shear-yielding haunches can be used for seismic retrofit and for new construction. In this study, shear-yielding haunch connections were investigated through experimental testing and finite element analysis. Three specimens were tested, each with a W1000 × 591 beam and W1000 × 554 column. The cyclically loaded specimens completed cycles at 0.04 rad prior to low-cycle fatigue of the haunch plates. The monotonically loaded specimen reached 0.064 rad drift. The experimental specimens had 10 to 15% post-yield stiffness, and the fuses reached the ultimate material strength prior to tearing. M-factors for the connection were determined to be 4.7 for life safety and 6.3 for collapse prevention. Finite element models were used to quantify force transfer through the connection and to investigate the retrofit-specific detail. The experiments and finite element models confirmed that a relatively simple design procedure produced acceptable designs.

Seismic design of reinforced concrete buildings equipped with viscous dampers using simplified performance-based approach

Passive control systems, such as Fluid Viscous Dampers (FVDs), have gained significant consideration in the design of earthquake-resistant structures. However, simple analysis and design methods are scarce for more practical and feasible implementation. This study provides a simplified procedure for performance-based seismic design of Reinforced Concrete (RC) special moment resisting frame using nonlinear FVDs. It adopts an extended performance-based design approach, focusing on maximum displacement along with floor acceleration to control the overall behavior of the structure. The fundamental principle of the method is to achieve the fully stressed (effect of FVDs on response indices) design approach to place dampers, which is attained by placing dampers among the storeys where drifts exceed the pre-decided performance limits. Further, a uniform damage distribution concept is followed to maximize the dampers' capacity. This study examines a rectangular-shaped RC SMRF with dampers to get the required performance when subjected to design basis and maximum considered earthquake levels. To check the efficacy, the proposed method is contrasted with a practical design method and a standard placement method employed in previous studies for RC structures with dampers. The analysis shows that the structure meets the performance targets of the design basis and the maximum considered level of earthquake hazards using the proposed step-by-step procedure. The comparison with the other two methods confirmed that the structure with dampers improved seismic behavior with the suggested process. Structural engineers can refer to the proposed method for the design of RC buildings with FVDs.

Sensitivity of sustainable urban drainage systems to precipitation events and malfunctions

Abstract In recent years, sustainable urban drainage systems (SUDSs) have become increasingly popular, sometimes taking over large parts of conventional stormwater management. SUDSs are usually designed using simple design procedures based on statistical rainfall data, without long-term simulations or real rainfall events. In addition, there is little experience of how SUDS respond to potential failures and malfunctions, often caused by ageing infrastructure and lack of asset management. Based on these two factors influencing the hydrological performance of SUDS, this study investigates the sensitivity of seven different SUDSs to rainfall events and malfunctions. The study was conducted using the SWMM 5.2 modeling software and the low impact development (LID) module was implemented for a period of 60 years. The SUDS are studied as individual infrastructure and as part of a small urban catchment. The results show that only the green roofs and rainwater cisterns have a statistically significant correlation between the length and return period of rain events and runoff values, with higher correlations for longer rain events. In contrast, the failures and malfunctions investigated can have a significant impact on the hydrological performance of SUDS. In particular, the design return period of SUDS was occasionally significantly exceeded for the strong malfunction scenarios studied.

A non-linear static analysis for the seismic design of single-span integral abutment bridges

Integral abutment bridges are characterised by a monolithic connection between the deck and the abutments. Because of this connection, the seismic behaviour of the entire structure tends to be controlled by its interaction with the surrounding soil, and especially with the approach embankments. To date, methods for the seismic design of this type of bridges are still characterised by substantial uncertainties, mostly because of insufficient understanding of the dynamic response of the soil–structure system. This paper provides a contribution to the interpretation of the seismic behaviour of integral abutment bridges, focusing on a single-span structural scheme that has been receiving significant attention in recent years. The dynamic interaction between the bridge and the soil is studied with global numerical models of the soil–bridge system developed in OpenSees and subjected to a variety of ground motions. The results of the dynamic simulations, interpreted also with the aid of a modal analysis of the system, are used to develop and finally validate a simplified design procedure. This procedure is based on the capacity spectrum method, aimed at evaluating the maximum deformation and internal forces in the structure produced by the longitudinal component of the seismic motion that typically dominates the design of integral bridges.

Anisotropy and cyclic loading characteristics of a stiff Bolders Bank glacial till at Cowden

Glacial tills are widespread across the world, common in northern Europe and found under the North and Baltic Seas. Their geological and geotechnical characterisation is important to the geotechnical design of a wide range of onshore and offshore structures. This paper reports outcomes from coordinated monotonic small-strain stress probing, cyclic and larger strain triaxial and hollow cylinder apparatus (HCA) testing on a natural low-to-medium plasticity, apparent highly over consolidated, stiff glacial clay till. Monotonic HCA and triaxial experiments investigated the till’s stiffness and shear strength anisotropy from its limited linear elastic range up to ultimate failure, showing that stiffnesses are higher in the horizontal direction than in the vertical and that higher undrained shear strengths develop under “passive” horizontal loading than “active” vertical loading. The cyclic triaxial tests revealed the impact of cycling on effective stress paths and strain development, and cyclic stiffness degradation. Stable, metastable and unstable patterns of behaviour are identified, along with different cyclic failure modes, which are related to the till’s static yielding behaviour. The experiment results provide the basis for developing, testing and calibrating monotonic and cyclic constitutive models and establishing simplified design procedures for piles installed in comparable tills to support offshore energy and other structures.

Optimal robust control of nonlinear systems: inter-sample optimisation in sampled-data control

A methodology is presented for the design and implementation of robust controllers that optimise inter-sample performance for a broad range of nonlinear systems operated within a sampled-data environment. The methodology applies to nonlinear continuous-time systems described by state equations, and it allows for modelling uncertainties and constraints on maximal control effort. It is shown that there exist optimal robust state-feedback controllers that minimise inter-sample tracking errors for such systems, as long as an appropriate controllability requirement is met. A relatively simple design and implementation procedure for such controllers is described.

Low-Overhead RF Impedance Measurement Using Periodic Structures

Due to the need for higher reliability and performance from RF circuits, multi-port reflectometers are increasingly used as low-overhead impedance monitors. In this work, using periodic structures as multi-ports is proposed. Periodic structures impose a new constraint on the multi-port theory and simplify it significantly. This simplification leads to closed form solution for calibration and measurement procedures. The closed-form solution also shows that any arbitrary periodic structure will always have a unique solution for both procedures. Therefore, the proposed technique does not rely on frequency-dependent behavior of devices, such as directivity and phase shift to measure impedance. This fact leads to increased bandwidth and simplified design procedure. In addition, proposed multi-port structures can be calibrated by using fewer known loads than existing multi-port techniques. This fact, coupled with the closed-form solution, reduces computation overhead and test time. The theory and its robustness against non-idealities, such as part-to-part variation, are verified with Monte-Carlo simulations. A practical embodiment of the technique is demonstrated with EM simulations and hardware experiments. In this embodiment, the multi-port structure is embedded into an LC matching network. Hardware experiments show that the embedded multi-port structure can measure test loads with high accuracy from 1.5 GHz to 3.5 GHz, without degrading matching network performance.

The effect of the gravity column in the seismic design of steel CBFs

In this work, the effect of the gravity column in the seismic design of X-braced CBFs is analysed through a simplified design procedure. The analysis is performed by dividing the structural typology as a sum of two substructures: the Gravity Column (GC) substructure, with the primary aim of bearing vertical actions; and the Bracing substructure, mainly reacting to the horizontal actions. The analysis of the influence of the GC in the seismic design has been deepened by exploiting the Controlled Collapse Design Theory for CBFs. By imposing the collapse configuration, the storey displacement vector is obtained and, through the deformability matrix for the GC substructure, the horizontal actions acting on this substructure are defined. An analysis of the effects of seismic design is carried out considering the percentage of total shear force due to the GC substructure, for two case studies. In addition, a cost-(seismic) benefit analysis between the Controlled Collapse Design Theory and EC8 Design, is carried out.

Numerical investigation of the penetration of torpedo anchors in sand-overlying-nonhomogeneous clay deposit

This study presents a comprehensive investigation of torpedo anchors penetrating into sand-overlying-nonhomogeneous clay deposit, with the main objective of predicting the anchor embeddment depth after it penetrates through the top sand layer. The behavior of the torpedo anchor and soil failure mechanisms during the installation process are analyzed using large deformation finite element (LDFE) methods. To validate the numerical models, comparisons are made with data from existing centrifuge and field tests. An extensive parametric study is then conducted, exploring a wide range of soil properties, soil layer thickness, anchor velocities, and parameters related to torpedo anchor geometry. Two intriguing findings emerge from the analysis. Firstly, there is an evolving soil failure, with the strain-softening region expanding in the clay near the boundary between the two soil layers. Secondly, the velocity profile during both the acceleration and deceleration stages varies with different sand layer thicknesses, displaying a nonlinear relationship with the anchor's final embedment depth. Based on the findings, a simple design procedure is developed to account for the influencing factors on the anchor installation depth. This procedure is expected to be valuable for engineers seeking to estimate the behavior of torpedo anchor installations in sand-overlying-nonhomogeneous clay soil deposits.

Simplified nonlinear analysis of doubly corrugated cold‐formed steel arches

AbstractDoubly corrugated steel arches are made by pressing transverse corrugations on trapezoidal cold‐formed steel sheets. Several studies show that these transverse corrugations may have a significant detrimental effect on the stiffness and load‐bearing capacity of the original trapezoidal profile. This paper presents an experimental campaign aimed at investigating the effects of transverse corrugations on the behaviour of arches. The campaign includes reduced tests on flat sheets and sheets with a single corrugation, as well as full tests on arches with spans ranging from 10 to 20 m. Subsequently, a simplified design procedure based on nonlinear 2D beam finite element models is proposed. The models account for the transverse corrugation effects by using intermediate rotational springs and equivalent beam section areas, which are calibrated from the results of the reduced experiments. A brief sensitivity study of the finite element results with respect to different modelling factors is conducted, and the different effects of the corrugation assessed. Finally, the simplified finite element models are validated by comparing the experimental and numerical force‐displacement curves, which show reasonably good agreement. However, further research is needed to refine and extend the proposed procedure.

DER integrated BTB-VSI based DSTATCOM for PQ enhancement

ABSTRACT This article demonstrates the performance of back-to-back connected voltage source inverter (BTB-VSI)-based distribution static compensator (DSTATCOM). In the proposed system, a three-phase three wire electrical utility system (EUS) is integrated with distributed energy resources (DER) through BTB-VSI. It has drawn more attention due to enhanced active power filtering, simple design procedure and performs reliable operation. The objectives of the research work is to provide clean power for weak EUS with improved power quality (PQ) such as, better voltage regulation, improved power factor (P.F), reduced total harmonic distortion (THD), balanced voltage at point of common coupling (PCC) and better optimal active power flow control (OAPFC), and so on. An artificial neurocontrol technique Kernel Hebbian Least Mean Square (KHLMS) is chosen to determine the accurate reference source current for operation of voltage source inverter (VSI). The BTB-VSI performance is investigated on both shunt compensation and OAPFC. The proposed system is converted to a simulation model and hardware unit using MATLAB/Simulink software and SPARTAN−6 field programmable gate arrays (FPGA) controller. Finally, the Simulation and experimental results illustrate that the shunt compensating ability with OAPFC of BTB-VSI performs better over VSI as per IEEE Std 1159–2019 grid code.

Understanding the depressurization system design

AbstractA pressure relief valve (PSV) cannot depressurize a vessel or system; it can only limit its maximum pressure during upset or emergency conditions. A blowdown system is usually specified to accomplish the removal of the pressurized, volatile, hazardous, and flammable compounds such as hydrocarbon or ammonia vapor in vessels or systems. The pressure is removed from the vessel using a blowdown system; however, some hydrocarbon liquid will remain in the vessel. This paper explains different criteria for designing a blowdown system. Examples are presented to show how the blowdown time is affected by several factors. The Joule–Thomson effect and its effect on the vessel's inner wall temperature are illustrated using charts and tables. Several applications of the blowdown system are provided that relate to actual offshore and refining operations. Different mechanisms by which the blowdown system is activated are discussed, and a simplified design procedure to design a blowdown system is also provided.

Optimization of steel-reinforced wooden purlins

A new structural typology of a Steel-Reinforced Wooden (SRW) purlin made of rectangular laminated wood and C-section type cold-formed steel is presented in this article. The steel C-section profile is fitted onto the wooden purlin so that both work together as a composite unit. Although the wooden sections are weaker and have a lower elastic modulus than the steel sections, the overall dimensions of the SRW purlins are no larger than the steel C-section purlin sizes. The SRW purlins also form lighter structures than either plain steel or wooden purlins and they therefore have lower CO2 emissions. In addition, lighter purlins reduce the load on the main structure, which in turn reduces the material needed for the main structure of the building. So, reinforcement of the wooden purlin with steel sections within certain areas notably improved performance when compared with ordinary single-material purlins. The use of the SRW purlins can, therefore, improve the overall sustainability of a building. The improvements were analyzed in terms of sustainability and lower weight, as a function of span length and design load. The behaviors of the single material purlins and the SRW purlin were also compared. Both material strength and deformation design criteria and their influence were studied using an analytical approach based on loading and span length. The simple, innovative, and reliable design procedure described in this study ensured compliance with all technical requirements. Moreover, the savings relating to material weight were evaluated, neutralizing the carbon footprint in all cases under analysis.

Isolation and Purification of Single Gold Nanoclusters by Alternate Pumping Chromatography

Alternate pumping chromatography is applied to obtain atomically precise glutathione-stabilized gold nanoclusters in high purity from synthesized mixtures. On the basis of anion exchange chromatography, the feasibility of isolating a single cluster, Au10GSH10, as well as two different clusters simultaneously (Au25GSH18 and Au29GSH20) is demonstrated. In addition, Au18GSH14, which is present only in trace amounts, is successfully enriched. A simple design procedure is proposed that allows using columns with different retention behavior. Successful experiments with large injection amounts confirm the potential of the concept for preparative-scale productions of high-quality nanoparticulate products.

Strength prediction of a bottle-shaped strut for evaluating the shear capacity of reinforced concrete deep beam

For the analysis and design of reinforced concrete (RC) deep beams, the strut-and-tie model is typically employed to simulate the flow of stresses. A bottle-shaped strut develops between the loading point and support, in which compressive stress spreads laterally and induces tensile strain in the transverse direction, which reduces the compressive strength of the strut significantly. Web reinforcements are provided in deep RC beams to prevent splitting of the diagonal strut due to the presence of these transverse strains. In this article, a simplified design procedure based on the strut-and-tie model (STM) is proposed for the evaluation of the shear capacity of deep beams with web reinforcement. The suggested model is based on modified compression field theory and considers the impact of shear reinforcement ratio, transverse tensile strain, post-cracking strength of concrete, and the actual dispersion of compressive stress based on strut geometry (aspect ratio) for strength prediction of bottle-shaped struts. The experimental results of RC panels and deep RC beams reported in the literature are used to validate the results of the suggested model. The findings demonstrate that the proposed STM evaluates the shear capacity of deep RC beams more precisely than capacities estimated by ACI 318-19, AASHTO LRDF, and Eurocode 2 (EC2). In addition, a comprehensive parametric study has been carried out to investigate the effect of various design parameters on the shear capacity of deep RC beams.