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A new macro model for the finite element modeling of unreinforced masonry (URM) exhibiting in-plane nonlinear cyclic behavior is proposed. The ultimate objective is to predict the seismic response of multi-story URM buildings. The macro model enables the modeling of URM shear walls with a limited number of degrees of freedom (DOF) at low computation times. The macro model consists of a deformable elastic frame supported by diagonal struts with nonlinear behavior aiming to capture all dissipative phenomena occurring during seismic events. The nonlinear constitutive behavior of diagonal struts is inspired by models documented in the literature, ensuring a robust foundation for the proposed approach. This paper first provides a comprehensive review of the principal models currently available for URM analysis. It then articulates the rationale behind the development of this new numerical model, aiming to address the limitations encountered in existing methodologies and to offer a simple and fast tool for predicting the seismic behavior of URM buildings. Afterward, the new model is presented and tested with the simulations of two experimental campaigns performed on different URM walls. The comparison between experimental and numerical results shows that with a limited number of DOF and parameters, it is possible to obtain a prediction of the experimental results with satisfying accuracy. [ABSTRACT FROM AUTHOR]

—Reversible Logic Gates have become very popular for their uninhibited merits like, low power consumption, low garbage output, decreasing the quantum cost, least propagation delay etc. Several circuits have been designed for reversible logic ICs using conventional CMOS technology. But, as the CMOS technology is suffering from scaling down problems, the researchers have moved themselves towards post CMOS devices for further fabrication of Reversible ICs. Among different post CMOS devices, in SET, electrons are tunnelling through the channel one by one, so it offers ultra-low power dissipation compared to the traditional CMOS though it has high speed, high gain like properties. So the hybridization of CMOS-SET can achieve a useful effect on VLSI design, and the new technology is known as Hybrid CMOS-SET (HCS). But as the Hybrid CMOS-SET requires two distinct software, the HCS macro model has become very useful, as it can be simulated by using a single software. In this present paper, the reversible logic gate has been designed using the HCS macro model and is also being simulated using a single software, MATLAB with SIMULINK, with low power consumption.

A new macro model for the finite element modeling of unreinforced masonry (URM) exhibiting in-plane nonlinear cyclic behavior is proposed. The ultimate objective is to predict the seismic response of multi-story URM buildings. The macro model enables the modeling of URM shear walls with a limited number of degrees of freedom (DOF) at low computation times. The macro model consists of a deformable elastic frame supported by diagonal struts with nonlinear behavior aiming to capture all dissipative phenomena occurring during seismic events. The nonlinear constitutive behavior of diagonal struts is inspired by models documented in the literature, ensuring a robust foundation for the proposed approach. This paper first provides a comprehensive review of the principal models currently available for URM analysis. It then articulates the rationale behind the development of this new numerical model, aiming to address the limitations encountered in existing methodologies and to offer a simple and fast tool for predicting the seismic behavior of URM buildings. Afterward, the new model is presented and tested with the simulations of two experimental campaigns performed on different URM walls. The comparison between experimental and numerical results shows that with a limited number of DOF and parameters, it is possible to obtain a prediction of the experimental results with satisfying accuracy.

This work presents a macro model for discrete-time sigma‒delta modulators, which can significantly reduce the simulation time compared to transistor level circuits. The proposed macro model is realized by effectively combining active and passive ideal circuit components with Verilog-A modules. As such, since the macro model is a true representation of the actual transistor level circuit, a moderately good accuracy can be obtained. In addition, the proposed macro model includes the major amplifier, comparator, and switch‒capacitor non-idealities of the sigma‒delta modulator such as amplifier DC gain, GBW, slewrate, comparator bandwidth, hysteresis, parasitic capacitance, and switch-on resistance. The results show the simulation time of the proposed macro model sigma‒delta modulator is only 6.43% of the transistor level circuit with comparable accuracy. As a result, the proposed macro model can facilitate the circuit design and leverage non-ideality analysis of discrete-time sigma‒delta modulators. As a practical design example, a second order discrete-time sigma‒delta modulator with a five-level quantizer is realized using the propose macro model for GSM and WCDMA applications. [ABSTRACT FROM AUTHOR]

Recent decades have seen increased interest in using the controlled rocking concept in seismic resisting systems. Unlike conventional systems, where lateral deformation of a member is achieved through the formation of plastic hinges in critical regions, in the rocking systems this is achieved through a gap opening mechanism. Due to gravity load and/or post-tensioning forces, the rocking systems exhibit a self-centering behavior. Conducting a continuum finite element analysis to investigate the seismic response of such a system is quite expensive in terms of computational resources. On the other hand, a simplified macro model using two springs to simulate the gap opening/closing mechanism cannot accurately predict the dynamic response of the system. This study utilizes a multiple-spring model to simulate the nonlinear seismic response of circular tubular steel piers. An efficient optimization procedure based on a genetic algorithm is developed to calibrate the parameters of the springs. The results of continuum finite element analyses are compared with those obtained from the multi-spring model to verify the accuracy of the model. The proposed method is shown to be advantageous for accurately simulating the seismic response of a bridge model subjected to multi-directional ground motions, particularly the hysteretic force-displacement relationship, and dynamic response time history. • Seismic response of posttensioned (PT) rocking steel bridge piers is investigated through continuum and macro finite element (FE) modeling approaches. • Computationally efficient macro modeling approaches, i.e., two and multi -spring macro models, are discussed. • A procedure for calibrating the parameters of the multi-spring model using genetic algorithm is presented. • The performance of two-spring and multi-spring macro models in predicting the seismic response is examined. • Multi-spring macro model is extended to simulated the response of double rocking configuration. [ABSTRACT FROM AUTHOR]

The steel slit shear panel (SP), made by cutting slits in a monolithic steel plate, dissipates seismic energy through the flexural behavior of individual plate links separated by slits. To investigate the influence of different link designs and steel properties, three scaled SP specimens are designed and tested under quasi-static cyclic loading. Test results show that plate links with a larger width-thickness ratio buckle earlier and larger, and associated pinching in hysteresis is more serious. Significant strain hardening of low yield steel promotes plump shear hysteresis even with obvious out-of-plane buckling deformation. To investigate the effect of different SPs on the overall structural performance, moment resisting steel frame (MRSF) structures installed with SPs are built. Time-history analysis results show that the installation of SPs reduces the story displacement responses but increases the floor accelerations. The low yield SP works best in reducing both the maximum and residual inter-story drift. [ABSTRACT FROM AUTHOR]

To establish a more accurate, flexible, and practical performance evaluation method for unbonded precast prestressed concrete (PCaPC) frames, a macro model was illustrated based on the exterior beam–column sub-assemblages of unbonded PCaPC frames, which considers different tensile forces of the post-tensioned tendons (i.e. unsymmetrical tendon forces) and high-strength concrete. Based on the macro model, closed-form equations of beam axial shortening were provided by precisely considering the deformation compatibility and force equilibrium conditions along the beam. In this study, the iteration method for the comprehensive evaluation of different performance limit states, as well as the load–deformation relationship of the beam–column sub-assemblages, were constructed and simplified. Accuracy and superiority of the proposed evaluation methods were verified by comparison with experimental data and evaluation results of previous methods. Both damage tolerance and self-centering performance of unbonded PCaPC frames can be more accurately measured by the proposed methods. Meanwhile, the consideration of unsymmetrical tendon forces makes the methods more flexible for different types of unbonded PCaPC frames. In addition, parametric study was conducted to understand the effects of critical design parameters on the performance limits. Preliminary design advices were given to show the application potential of this study. [ABSTRACT FROM AUTHOR]

The deployment of MicroElectroMechanical System (MEMS) cantilever in the electronic systems is continuously increasing. These devices are usually interfaced with electronic circuits. It is important to build its macro model for rapid system design and simulation. This paper proposes development of an electromechanical coupling macro model of electrostatically actuated MEMS cantilever for straight and curled beam configurations. It consists of linear electrical components and nonlinear dependent sources, which represent mechanical parameters and electromechanical coupling in the system. In order to model device mechanics, analytical formulations are done and calculations are adapted to macro model. A methodology to derive electromechanical coupling as a function of bias voltage is developed. This electrical model is capable of predicting the device characteristic behaviour before the onset of pull-in instability region and estimates pull-in voltage. Such macro model can be easily implemented in any circuit simulation platform and be used to demonstrate the possible advantage of using this scheme for device and system dynamics optimization. To arrive at equivalence, an analytical formulation for spring constant and pull-in voltage of cantilever based on the partial load distribution and curling is derived. It utilizes the methodology based on nonlinear electrostatic pressure approximated by its linearized uniform counterpart and mechanical force-deflection model. An electrical characterization of fabricated MEMS cantilever is done to obtain the experimental value of pull-in voltage. Simulation Program with Integrated Circuit Emphasis (SPICE) simulations results for the developed model is obtained for actual device dimensions and is in good agreement with analytical and experimental results.

Per- and polyfluoroalkyl substances (PFASs) are used in industrial production and manufacturing but were repeatedly detected in agricultural soils and therefore in cash crops in recent years. Dissipation of perfluoroalkyl acids (PFAAs), a sub-group of PFASs, in the environment was rather attributed to the formation of non-extractable residues (NER) than to degradation or transformation. Currently, there are no models describing the fate of PFAAs in the soil-plant continuum under field conditions, which hampers an assessment of potential groundwater and food contamination. Therefore, we tested the ability of the pesticide-leaching model MACRO to simulate the leaching and plant uptake of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in a field lysimeter using two concepts of adsorption: a kinetic two-side sorption concept usually applied for pesticide leaching (scenario I) and the formation of NER (scenario II). The breakthrough of substances could be simulated adequately in scenario II only. Scenario I, however, was not able to reproduce sampled leaching concentrations. Plant uptake was simulated well in the first year after contamination but lacked adequacy in the following years. The model results suggest that more than 90% of PFOA and PFOS are in the pool of NER after 8 years, which is more compared with other studies. However, since NER formation was hypothesized to be a kinetic process and our study used a PFASs leaching time series over a period of 8 years, the results are reasonable. Further research is required on the formation of NER and the uptake of PFAAs into plants in order to gain a better model performance and extend the simulation approach to other PFAAs. [ABSTRACT FROM AUTHOR]

In order to make the dispatching of urban water supply system more scientific and achieve the goal of energy saving and consumption reduction, the feasibility of macro-model of water supply system was established and verified, and the accuracy and advantages of macro-model were also verified. Based on this model, a first-level optimization model with minimum cost as the goal was established to redistribute the flow and pressure of multi-source water supply system. Based on the first-level optimization results and macroscopic model theory, a second-level optimal dispatching model was established, and the Genetic Algorithm with strong optimization ability was used to solve the problem. The two-level optimal dispatching of water supply system in a northern city was carried out. The results show that the overall water supply cost decreases after primary optimization compared with that before optimization; after the second-level optimization, the combination of the pumps has changed greatly, the speed regulating device has been fully utilized, and the energy consumption of the whole water supply system after optimization is lower than that of before optimization. Therefore, it is feasible to carry out two-lever optimal dispatching of urban water supply system in northern cities, which can achieve the purpose of energy saving and consumption reduction. [ABSTRACT FROM AUTHOR]

Abstract Cold-formed steel (CFS) shear walls are the primary lateral load resisting components in lightweight steel framed (LSF) structures. The development of increasing complex LSF structures, laterally supported by CFS walls, demands sophisticated modelling techniques for design and optimization that typically involves inherent material and geometric nonlinearities caused by large deformations. Determining the performance of CFS shear walls and accurately establishing their behavioural model are the foundations of obtaining effective responses of CFS structure under extreme loading conditions. Great progress has been made on the theories and applications of the numerical models for analysis of the lateral behaviour of CFS wall systems during the past several decades, and quite a great number of numerical models have been developed for simulating the behaviour of CFS shear walls in the literature. This study provides a comprehensive review on the numerical developments made in this area as published in leading journals, high impact conferences and codes' provisions in the area, and looks at the challenges and gaps that need to be addressed in future research studies. The numerical models for analysing the lateral behaviour of CFS shear walls including their strengths, weaknesses, limitations employed behavioural models, contributing factors, and parameters and functions influencing their performance are discussed and compared with each other. The existing models are grouped into two categories: micro modelling methods, which simulate fine-scale details; and macro modelling methods, which amalgamate details into selected categories for further simplification. Highlights • Review of the numerical developments in the lateral behaviour of CFS wall systems. • State of the art of the theories and applications of numerical models for CFS walls. • Classification of methods and discussions on strengths, weaknesses, and limitations. • Discussions on challenges and gaps to be addressed in the future research studies. [ABSTRACT FROM AUTHOR]

In this paper, two theoretical models, micro and macro model, are presented to investigate the effect of circumferential cracks on the structural characteristics of a pipe. In the micro model, the equivalent bending stiffness is obtained based on the energy method and fracture mechanics. Because of the high change of strain energy near the crack location, the variation is represented by reduction in the bending stiffness along the length of the pipe. The development of the macro model is based on a simplified procedure, i.e., the pipe is separated into two segments without any change in the cross section property. Two separated pieces are connected by a rotational massless spring of the infinitesimal length inserted at the crack location. Moreover, it is shown that in the macro model so smaller number of elements are required than the micro model to provide a sufficient accuracy. Finally, the experimental measurements are utilized to validate the proposed models. The deflections and frequencies obtained for several cases through the displacement and vibration method, using the proposed models agree reasonably well with the experimental measurement data. [ABSTRACT FROM AUTHOR]

Highlights • Aggregate Crash Prediction Models (ACPMs) act as the primary planning tool to identify how any increase in a specific mode-ridership will contribute to crash frequencies. • ACPMs provide the basic tool for evaluation of travel demand management (TDM) scenarios regarding modal shares in urban transportation planning. • A certain TDM scenario may be developed to reduce modal share of a specific mode and the related change in crash frequency could be predicted by the appropriate ACPM. Abstract Introduction Long-range transportation plans often involve proposals for improvements/ changes in different modes of travel. This means that modal share of trips generated at each traffic analysis zone (TAZ) by mode of travel needs to be predicted/ forecasted for safety evaluation purposes. The objective of this research study is to develop a series of aggregate crash prediction models (ACPMs) that relate with the modal split step of the conventional four-step demand models. Method The models are developed utilizing network and vehicular, socio-economical, trip production/attraction and trip frequencies by mode at TAZ-level as explanatory variables in a generalized linear regression with the assumption of a negative binomial error structure. Crash frequencies are split into total crashes (TC) and severe crashes (SC). Results The models prove promising in estimating crash frequencies upon changes in modal shares, which is essential in safety assessment of alternate transportation demand management (TDM) scenarios. Trips made in car, bus, and bus Service mode became significant in the estimated TC and trips made in car, taxi, school service, bus service and moped mode became significant in the estimated SC ACPMs. Conclusions The ACPMs may be used from two different points of view. First and most appropriate use is to consider these as tools to forecast future crash frequencies and develop long-term plans to counteract. In the second point of view, ACPMs act as the primary planning tool to identify how any increase in a specific mode-ridership will contribute to crash frequencies. This is of great interest in developing plans that involve increased use of a specific mode. Practical application As modal shares are forecasted in certain years into the future by the modal split step of demand modeling, crash frequencies could also be forecasted and safety implications of mobility improvement scenarios (e.g. increased number of trips by bus, car, etc.) would be evaluated. [ABSTRACT FROM AUTHOR]

Using time series data over the period of 1984–2015, this paper applies the combined autoregressive distributed lag (ARDL) and vector error correction model (VECM) approach to identify short- and long-run causal relationships between the number of road accidents and social economic development, including increase of GDP, growth of population, expansion of road infrastructure, and growth of private car ownership. The results confirm a long run relationship between those four social economic variables and road accidents frequency in which growth of population and private car ownership lead to long-run increases in the number of road accidents while road network expansion leads to a long-run decrease in road accidents number in Hong Kong. Additionally, the correlation inside of social economic variables are examined and reported. Insights that obtained from this study are expected to help with evaluating new policies and programs currently being implemented for verifying if they could contribute to a major improvement of road safety in Hong Kong. [ABSTRACT FROM AUTHOR]

Thermal errors constitute a significant portion of overall machining errors observable on any machined component, especially if produced through high-speed machining. Major reasons for these thermal errors are from the distortion of the spindle and/or other machine tool components from their respective reference positions, which in turn, is due to change in temperature of machine tool components. The heat generation within the spindle due to internal sources such as motor and bearings can be regarded as the main culprit, especially at high cutting speeds. Although conventionally, cooler units with Ambient temperature Tracing Strategy (ATS) are employed to extract heat from the spindle, they are not very effective when accuracy and precision of machined components are of utmost importance. In this paper, research work is presented wherein, the effectiveness of cooling is significantly improved by employing a model-based control strategy on a traditional bath recirculation cooler unit. This strategy, called Cooler Trigger Model (CTM), involves dynamically controlling the switching frequency and the switch ’ON′ time of cooler compressor so that the heat extraction is in accordance with the heat generation. Specifically, the approach is based on a macro model involving a combined heat power and energy criteria wherein the former criterion is analogous to a conventional ’ON-OFF′ controller with the exception that the field variable is chosen as heat rate (extraction with respect to generation) instead of temperature. Meanwhile, the heat energy criterion pitches in to limit cooling in the spindle due to a few design and operational constraints. In order to illustrate the effectiveness of CTM strategy, a comparative mathematical analysis of ATS and CTM cooling strategies is performed for Environment Temperature Variation Error (ETVE) test. Further, it is shown that CTM strategy is advantageous with respect to the motor and bearing temperature stabilization for a wide range of spindle speeds, thereby leading to significant reduction of thermal errors when compared with ATS. [ABSTRACT FROM AUTHOR]

Performance of Single Electron Transistors as analogue frequency doublers is evaluated by analysis and HSPICE simulations. First, a macro model is selected which represents the device characteristics adequately. The model parameters are determined for different devices reported in the literature, based on their DC characteristics. Adding terminal capacitances to the device model, the small-signal AC performance of the transistors are then simulated. It is observed that the selected devices can operate up to GHz frequencies. Then large signal theory of operation of a common source doubler with resistive loading is developed based on the selected model. Simulations for resistor and transistor loaded circuits with HSPICE are also presented. There is good agreement between the simulation results and those from the closed form analytical expressions. The device analysis and simulations indicate that the device can be used as a doubler in its Coulomb blockade region of operation. Conversion gain (loss) of −13 dB, and harmonic distortion of 12% can be expected. [ABSTRACT FROM AUTHOR]

Summary: The role of masonry infills in the seismic behavior of reinforced concrete buildings has been widely studied in terms of their strength and stiffness contribution in the in‐plane (IP) direction, while fewer studies have been carried out on their response and modeling in the out‐of‐plane (OOP) direction. In this paper, the state of the art in code and literature provisions regarding infills' OOP capacity and seismic demand is presented, together with a review of the experimental tests that have been carried out to investigate infills' OOP behavior and the effects of IP‐OOP interaction. This review aims to collect an experimental database that is used to evaluate the effectiveness of literature and code provisions and to propose a semiempirical approach both for predicting infills' OOP strength, stiffness, and displacement capacity and for modeling the effects of IP displacement demand on OOP behavior and vice versa. Then, the state of the art on modeling of infills' OOP behavior and IP‐OOP interaction is presented together with a new macro model based on the proposed formulations and conceived to represent the IP and OOP behavior by taking into account the mutual interaction effects. Finally, the proposed model is used for an example application on two case‐study buildings, showing the effects of taking into account or neglecting the IP‐OOP interaction phenomena. [ABSTRACT FROM AUTHOR]

Inter-module connections (IMC) are a research focus closely related to the robustness of steel volumetric buildings (VB). Many IMC have been proposed by numerous researchers and engineers, experimentally tested and numerically studied using finite element models. However, there are insufficient IMC macro models available, which imposes challenges for engineers to construct a global numerical VB model. Hence, this study aims to close the gap with a component-based macro-mechanical model for the macro-modelling of IMC in steel VB. In this paper, a comprehensive IMC database was collected to identify and characterise the active components. Two types of macro-mechanical models (H-shape and Q-shape) consisting of P-V-M links have been proposed and a novel uplifting mechanism has been derived for a typical IMC (bolted tie plate with shear key). The proposed macro-mechanical model and other existing macro-models were then compared with existing pushover experiments from an IMC subassembly. The proposed macro-mechanical model shows a good match to the existing experimental results, and it is adaptable to existing IMC. • A component-based macro-mechanical model for inter-module connections (IMC) is proposed. • A comprehensive IMC database was collected to identify and characterise the active components. • A novel uplifting mechanism is derived for a typical IMC (bolted tie plate with shear key). • The proposed macro-mechanical model is compared with existing pushover experiments of IMC subassembly. [ABSTRACT FROM AUTHOR]

Timber folded surface structures assembled using semi-rigid multiple tab and slot joints (MTSJ) have been shown to form feasible structural systems with high load bearing potential. However, for their further development and use on large building scales, a pertinent model for prediction of their structural behaviour has yet to be developed. This paper focuses on simplified numerical methods for accurately modelling the semi-rigid structural behaviour of bidirectional timber folded surface structures with multiple tab and slot connections. Within this scope, the structure behaviour is considered to be in the elastic stage. Three practical methods of analysis for such structural systems are presented. The first two approaches use the Finite Element Method (FEM), where the theory of plates and shells are applied. In the first method, the MTSJs are modeled using strip element models, while, in the second strategy, spring models are used. The third modeling strategy elaborates on the new macroscopic mechanical models, referred to as macro models. Sets of one-dimensional (1D) elements are used to represent the mechanical behaviour of the entire system. Both linear and geometric nonlinear analysis are performed for all three modeling strategies. The numerical results are then validated against the large scale experiments. Comparison of the strip and spring element model results have shown that the strips represent more accurately the experimentally obtained values. Concerning the macro modelling approach, very good agreement with both detailed FE modelling approaches, as well as experimental results, were obtained. The results indicate that both linear and nonlinear analysis can be used for modelling the displacements within the elastic range. However, it is essential to include geometric nonlinearities in the analysis for accurate modelling of occurring strains as well as for displacements when considering higher load levels. Finally, it is demonstrated that including semi-rigidity in the numerical models is of high importance for analysing the behaviour of timber folded surface structures with MTSJ.

The article presents some problems of seat belt use by car drivers and passengers. It looks in particular at seat belt use and effectiveness in selected countries. Next, factors of seat belt use are presented and methodology of model development. A macro model of seat belt use is presented based on data from around fifty countries from different continents.

During the past decades, various analytical macroscopic models of structural walls have been developed for simulating the seismic behavior of reinforced concrete (RC) walls. Due to the inherently complicated characteristics of RC walls, macroscopic models that can capture all the important response characteristics with good accuracy and applicability are very challenging to establish. A thorough review of the four main types of mathematical macro models of RC walls, i.e., the vertical-line-element-model, the 2-D shear panel element model, the equivalent truss model and the fiber-based model, is presented to discuss the methodology behind each model and examine the corresponding merits and disadvantages. Suggestions are also made for the further research of the macro modeling of structural walls. [ABSTRACT FROM AUTHOR]

This study evaluates the effectiveness of a newly developed retrofitting scheme for masonry-infilled non-ductile RC frames experimentally and by numerical simulation. The technique focuses on modifying the load path and yield mechanism of the infilled frame to enhance the ductility. A vertical gap between the column and the infill panel was strategically introduced so that no shear force is directly transferred to the column. Steel brackets and small vertical steel members were then provided to transfer the interactive forces between the RC frame and the masonry panel. Wire meshes and high-strength mortar were provided in areas with high stress concentration and in the panel to further reduce damage. Cyclic load tests on a large-scale specimen of a single-bay, single-story, masonry-infilled RC frame were carried out. Based on those tests, the retrofitting scheme provided significant improvement, especially in terms of ductility enhancement. All retrofitted specimens clearly exhibited much better performances than those stipulated in building standards for masonry-infilled structures. A macro-scale computer model based on a diagonal-strut concept was also developed for predicting the global behavior of the retrofitted masonry-infilled frames. This proposed model was effectively used to evaluate the global responses of the test specimens with acceptable accuracy, especially in terms of strength, stiffness and damage condition. [ABSTRACT FROM AUTHOR]