Dynamic Simulation

The current equations describing the dynamic rheology of polymer melts provide the correlations between the modulus of visco-elasticity, G*(w), split into its elastic and viscous moduli, G'(w) and G"(w), respectively, and the frequency of the shear deformation applied to the melt, w. The dynamic viscosity of the melt, ETA* = G*/w is usually used to compare melts of different chemical nature or to study the effect of molecular weight, M, its dispersity, and the presence or the absence of branches, short or long. The equations also describe the influence of external variables on the rheological state of the melt: temperature and pressure. The terms and constants that enter the equations of rheology have themselves been interpreted, to a large extent, by molecular mechanisms triggered by the changes occurring to the statistical description of the individual chains: the dynamic molecular models of Rouse (for un-entangled melts) and of de Gennes (reptation) for entangled melts illustrate the current formulation and understanding of the rheology of polymer melts. On the other hand, we have pointed out in several publications the problems surfacing in the classical molecular interpretation of the rheological data when revisited by our analysis, and the contradictions arising from these models when they are applied to the understanding of new experimental work on “the strain-induced time dependence of the melt viscosity” leading to the technologies of “Rheo-Fluidification” of melts and of their “sustained-Orientation”. In short, we have concluded that the current comprehension of the visco-elasticity of polymers, in particular of the entanglement concept, is not compatible with the reality of new experimental facts and, therefore, that the current accepted theories should be debated and revised; more generally, that a different approach to the physics of interactions in polymers should be considered. We have already introduced the principles of such a theory of interactions of Dual-conformers in which the statistical system is no longer a single macromolecule, but a self-generated collective network of Dual-Conformers belonging to the macromolecules. The local deformation of the Dual-conformers and the collective network enthalpy and entropy are interactively emerging from the solution of the Grain-Field Statistics applied to the interactions between the Dual-conformers, demonstrating the dissipative character of the solutions: this is our new foundation to explain the observed experimental facts, old and new, regarding the visco-elastic effects of melts under shear-deformation, linear or non-linear. This paper presents the Dual-Phase Rheology Protocol (DPRP) i.e. how to derive the parameters of the new statistical approach from the visco-elastic moduli G’(w,T) and G”(w,T) in dynamic rheology. In particular, it is shown that a completely different empirical presentation of the rheological results can be expressed in terms revealing the relevance of the Dual-Phase and Cross-Dual-Phase concepts. We introduce, for the 1st time, an empirical analysis of the data that permits to relate the rheological properties of an entangled melt (M > Mc, the entanglement molecular weight) to the stability of the solution presented by the split of Dual-Phases into Cross-Dual-Phases. In other words, the “entanglement” of the macromolecules can be quantified in terms of the viscosity, ,  and the intrinsic elasticity, kappa=(G’/G*)^2 of the individual interactive Dual-Phases emerging from the split to re-establish a new rheological stability of the melt as M increases. This paper also introduces a roaster of new rheological markers that can be traced to analyze phenomena visible in rheology, widening the panel of analytical tools available to characterize difficult situations (blends, branches etc.).

An approach to quantitatively assess the effects of nucleation transience on the kinetics of crystallization under static and dynamic conditions is proposed. The approach is based on an order of magnitude analysis that involves time scales characterizing the rates of nucleation relaxation and processing. The method is implemented to evaluate the effects of nucleation transience on kinetic computations performed in the tungsten-carbon system. The assessment is verified by contrasting the kinetics computed by means of a cluster dynamics simulation that implicitly accounts for transience to those evaluated using a quasi-steady-state model. When interpreting the kinetics of tungsten carbide surface crystallization, the proposed scaling method predicts that under static conditions transient effects need to be accounted for when annealing below 2600 K, while under dynamic conditions transient effects become important when quenching at ultrahigh cooling rates such as 10 8 K/s. Accordingly, in the case of isothermal annealing the steady-state kinetics appears to be in good agreement with those computed dynamically above 2600 K, but gradually deviates at lower temperatures. Consequently, the steady-state model underestimates the transformation time by more than an order of magnitude at the nose of the TTT curve ͑ϳ2200 K͒. In the case of continuous cooling, the kinetic rate is well approximated by the quasi-steady-state model for processing rates of 10 4 and 10 6 K/s; however, for ultrahigh cooling rates of order 10 8 K/s, the kinetics computed by the quasistatic model deviates substantially from that computed using cluster dynamics. As a consequence, the crystallized fraction computed from the quasistatic model is overestimated by at least an order of magnitude at every undercooling temperature. The results from the two kinetic models appear to validate the assessment of transience based on the proposed scaling method.

An approach to quantitatively assess the effects of nucleation transience on the kinetics of crystallization under static and dynamic conditions is proposed. The approach is based on an order of magnitude analysis that involves time scales characterizing the rates of nucleation relaxation and processing. The method is implemented to evaluate the effects of nucleation transience on kinetic computations performed in the tungsten–carbon system. The assessment is verified by contrasting the kinetics computed by means of a cluster dynamics simulation that implicitly accounts for transience to those evaluated using a quasi-steady-state model. When interpreting the kinetics of tungsten carbide surface crystallization, the proposed scaling method predicts that under static conditions transient effects need to be accounted for when annealing below 2600 K, while under dynamic conditions transient effects become important when quenching at ultrahigh cooling rates such as 108 K/s. Accordingly, ...

Most industrial scale reactive distillations (presently more than 150), operated worldwide today at capacities of 100-3000 ktonnes/y, and are reported in this paper. Most of these plants started up less than 15 years ago. The drivers, processes, systems, scale-up methods and partner collaborations for this rapid invasion of a new process intensified technique are explained in this paper. The business drivers are (a) economical (prosperity): variable cost, capital expenditure and energy requirement reduction. In all cases these are reduced by 20% or more, when compared to the classic set-up of a reactor followed by distillation. (b) Environmental (planet): lower emissions to the environment. In all cases carbon dioxide and diffusive emissions are reduced and (c) social (people): improvements on safely, health and society impact are obtained by lower reactive content, lower run away sensitivity and lower space occupation. These industrial reactive distillation systems comprise homogeneous and heterogeneous catalysed, irreversible and reversible reactions, covering large ranges of reactions, notably hydrogenations, hydrodesulfurisation, esterifications and etherification. Various commercial methods for packing heterogeneous catalyst in columns are now available. The systems comprise amongst others: multiple catalyst systems, gas and liquid internal recycle traffic over these catalyst systems, separation, mass flow, and enthalpy exchange. These are integrated optimally in a single vessel, a characteristic feature of process intensification. The scale-up methods applied from pilot plants to commercial scale are brute force and modelling. Technology providers CDTECH and Sulzer Chemtech have used these scale-up methods successfully. Barriers perceived and real have also been removed by these companies. Chemical manufacturing companies have also developed their own specific reactive distillations by their own research and development. These companies, both on their own and in consortia, also developed heuristic process synthesis rules and expert software to identify the attractiveness and technical feasibility of reactive distillation. Heuristic rules and expert software will be presented and supported by examples. Academic research also produced design methods to identify the feasibility of reactive distillation, to determine the feed locations, to select packing types, to sequence columns optimally and also produced methods to design, optimise and control the columns with steady state and dynamic simulation models. The rapid commercial scale implementation of reactive distillation by co-operation of partners in research, scale-up, design and reliable operation can also be seen as a model for rapid implementation of other process intensification techniques in the chemical industry.

The Activated Sludge Model No. 1 (ASM1) is a widely adopted structured model used to simulate the dynamic behavior of aerobic biological processes in wastewater treatment systems. It provides a robust framework for the optimization of existing facilities and the design of new treatment infrastructure. In this study, a modified ASM1 model, implemented in GPS-X 8.1 software, was applied to the Beja wastewater treatment plant (WWTP) in Tunisia, which receives a mixed influent composed of domestic sewage and high-strength industrial effluent from a baker's yeast factory. Model calibration was carried out using daily operational data, including total chemical oxygen demand (TCOD), total suspended solids (TSS), and total biochemical oxygen demand (TBOD₅). A comprehensive sensitivity analysis and automated optimization procedure were conducted to identify the most influential parameters and determine their optimal values. Key stoichiometric and kinetic parameters-including the maximum specific growth rate (µH), decay rate (b H), half-saturation constant (K SH), and biomass yield coefficient (Y H)-were calibrated, resulting in the following optimized values: Y H = 0.46 gCOD/ gDCO, µ H = 7.1 d⁻ 1 , K SH = 83.89 mg/L, and b H = 0.34 d⁻ 1. The simulation results demonstrated the model's ability to accurately reproduce plant performance under varying influent conditions. Notably, the model successfully captured the impact of industrial shock loads (COD concentrations ranging from 20 to 80 g/L) on treatment performance. Model validation showed strong agreement between measured and simulated effluent values for TCOD and TBOD₅, with root mean square error (RMSE) values of 10% and 15%, respectively, over a one-year period. However, TSS predictions were slightly less accurate, yielding an RMSE of approximately 25%. These results confirm the reliability and practical relevance of the ASM1 model as a decision-support tool for the management of WWTPs subjected to complex and variable influents. Its successful application to the Beja plant underscores its potential to enhance treatment efficiency, anticipate performance disturbances, and support sustainable plant operation under challenging industrial discharge conditions.

We show through rigorous calculations that small dielectric microspheres can be organized by an incident electromagnetic plane wave into stable geometric configurations, which we call photonic clusters. The longranged optical binding force arises from the multiple scattering between the spheres. A photonic cluster can exhibit a multiplicity of distinct geometries, including quasicrystal-like configurations, with exotic dynamics. Linear stability analysis and dynamical simulations show that the equilibrium configurations can correspond with either stable or a type of quasistable states exhibiting periodic particle motion in the presence of frictional dissipation.

A new field of robotics is emerging. Robots are today moving towards applications beyond the structured environment of a manufacturing plant. They are making their way into the everyday world that people inhabit. The paper focuses on models, strategies, and algorithms associated with the autonomous behaviors needed for robots to work, assist, and cooperate with humans. In addition to the new capabilities they bring to the physical robot, these models and algorithms and more generally the body of developments in robotics is having a significant impact on the virtual world. Haptic interaction with an accurate dynamic simulation provides unique insights into the real-world behaviors of physical systems. The potential applications of this emerging technology include virtual prototyping, animation, surgery, robotics, cooperative design, and education among many others.

This paper discusses intuitive and eficient ways to model and control the dynamics of highly redundant branching mechanisms using the operational space formulation. As the complexity of mechanisms increases, their modeling and control become increasingly dificult. The operational space formulation provides a natural framework for these problems since its basic structure provides dynamic decoupling among multiple tasks and posture behavior. Eficient recursive algorithms are presented for the computation of the operational space dynamics of branching mechanisms with multiple operational points. The application of these algorithms results in a significant increase in the interactivity and usability of dynamic control of complexbranching mechanisms. The experimental results are presented using real-time dynamic simulation.

A new field of robotics is emerging. Robots are today moving towards applications beyond the structured environment of a manufacturing plant. They are making their way into the everyday world that people inhabit. The paper focuses on models, strategies, and algorithms associated with the autonomous behaviors needed for robots to work, assist, and cooperate with humans. In addition to the new capabilities they bring to the physical robot, these models and algorithms and more generally the body of developments in robotics is having a significant impact on the virtual world. Haptic interaction with an accurate dynamic simulation provides unique insights into the real-world behaviors of physical systems. The potential applications of this emerging technology include virtual prototyping, animation, surgery, robotics, cooperative design, and education among many others. Haptics is one area where the computational requirement associated with the resolution in real-time of the dynamics and contact forces of the virtual environment is particularly challenging. The paper describes various methodologies and algorithms that address the computational challenges associated with interactive simulations involving multiple contacts and impacts with complex human-like structures.

Integrated assessment models (IAMs) have been widely applied to questions of climate change policy-such as the effects of abating greenhouse gas emissions, balancing impacts, adaptation and mitigation costs, understanding processes of adaptation, and evaluating the potential for technological solutions. In almost all cases, the social dimensions of climate policy are poorly represented. Econometric models look for efficient optimal solutions. Decision making perspectives might reflect broadscale cultural theory, but not the diversity of cognitive models in practice. Technological change is often ignored or exogenous, and without understanding of stakeholder strategies for innovation and diffusion. Policy measures are proposed from idealised perspectives, with little understanding of the constraints of individual decision makers. We suggest a set of criteria for IAMs that can be used to evaluate the choice and structure of models with respect to their suitability for understanding key climate change debates. The criteria are discussed for three classes of modelsoptimising econometric models, dynamic simulation models and a proposed agent-based strategy. A prototype agent-based IAM is reported to demonstrate the usefulness and power of the agent based approach and to indicate concretely how that approach meets the criteria for good IAMs and to complex social issues more generally.

The whole farm model FASSET ver. 1.0 was used for evaluation of the environmental and economic consequences of implementing different nitrogen taxes. The taxation policies analysed were a tax on nitrogen in mineral fertiliser, a tax on nitrogen in mineral fertiliser and imported animal feedstuff, and a tax on the farm nitrogen surplus. In these scenarios, the tax price was equal to the price of the nitrogen in mineral fertilisers (0.67 E kg N À1 ). Four farm types were considered: arable on sandy soil, arable on loamy soil, pig production on sandy soil and pig production on loamy soil. Impacts of the taxes for each farm type on crop rotation, fertiliser use and pig production were estimated by the Linear Programming module of FASSET. The dynamic simulation module of FASSET evaluated the environmental and economic consequences of the new production plans. The social abatement cost of reducing nitrate leaching varied between 1 and 9 E kg N À1 . None of the taxation policies was the most cost-effective for all farm types. Tax on mineral fertiliser favours pig producers, whereas the tax on nitrogen surplus favours arable farms. Thus efficient taxation schemes for reduction of nitrate leaching should differentiate between farm types rather than use uniform input taxes.

The SARS-CoV-2 virus's rapid and unrelenting dissemination necessitates a prompt effort to develop new antiviral drugs, which often requires time and money. To overcome these constraints, computer-based approaches, such as molecular docking, have become essential tools for quickly testing and assessing potential inhibitors. The literature review examines and combines recent studies from 2020 to 2023 on the application of molecular docking simulations to develop new antiviral drugs for the combatting of SARS-CoV-2.citation: By utilizing Google Scholar sources and extensive analysis of the literature, we categorized and analyzed target proteins, ligand libraries (including both repurposed drugs and natural products), and the docking software used in five specific computational studies through thematic synthesis. The findings demonstrate a consistent biological target, with all five studies focusing on the SARS-CoV-2 subunit. Primary taxa (Mpro or 3CLpro, PDB ID: 6LU7). The replication of the virus is dependent on this target, which is crucial because there are no comparable structures in humans. This is why reusing drugs was a popular strategy. They took advantage of existing drug safety records. Many promising drug candidates showed high binding affinities, stable hydrogen bonds, and low free binding energies. These drug candidate libraries were analyzed. Velpatasvir, Remdesivir and Ritonavir were among the drugs included, along with a new derivative called Compound 3d.

A comprehensive process investigation/design methodology is presented that combines economic, control, and environmental features. The methodology is presented on the case study of energy integrated distillation columns separating ternary hydrocarbon mixtures of different ease of separations. The economic features involve capital and operating costs; the controllability investigations are based on the evaluation of frequency dependent features and dynamic simulations; the environmental evaluation counts for the CO 2 emissions. The results show that the heat integrated scheme is practically the best selection from every point of view.

A comprehensive process investigation/design methodology is presented that combines economic, control, and environmental features. The methodology is presented on the case study of energy integrated distillation columns separating ternary hydrocarbon mixtures of different ease of separations. The economic features involve capital and operating costs; the controllability investigations are based on the evaluation of frequency dependent features and dynamic simulations; the environmental evaluation counts for the CO 2 emissions. The results show that the heat integrated scheme is practically the best selection from every point of view.

In this study, the forces and moments exerted by waves of Persian Gulf on the Abouzar 1200 crane barge have been determined. To achieve this, after simulating the waves of Persian Gulf and paneling the wetted surface of the Abouzar 1200 in its mean position and linearizing the boundary conditions, the velocity potential function was obtained using the Boundary Element Method. Using the linearized Bernoulli equation, the dynamic pressure distribution on the wetted surface was calculated. By integrating this pressure distribution over the wetted surface, the wave-induced forces and moments on the vessel were derived. These forces and moments are utilized in the dynamic analysis of the vessel.

The reference to Table seems incorrect here (as there is no Table ). Should it be Figure (2) The reference has been treated (here and elsewhere in the text) as . Is this correct? Q4: Au: All Figures are poor quality Figures. Please provide better quality Figures.

This paper presents two alternative procedures based on quantum/conductor-like screening model (COSMO) calculations and on molecular mechanics/dynamics simulations, respectively for estimating the PHSCT equation of state (EOS) parameters and to predict vapor-liquid equilibria (VLE) behavior for pure, alternative refrigerants, as well as for their binary mixtures. The quality of the predictions achieved with both method proposed, in conjunction with the confined computational time aspects involved, can be considered satisfactory, so that these strategies can be judged as promising routes toward an on-line coupling between molecular and process simulation.

A dynamic model of a single-effect absorption refrigeration cycle has been developed. Modeling of the cycle performance requires thermodynamic properties which are obtained from equations of state for refrigerant-absorbent mixtures. The transient response of the absorption refrigeration cycle is investigated using mass, momentum and energy balances for the different parts of the system. Some design and operation parameters that affect the cycle performance are identified.

Ilmenite smelters must be operated with the slag bath contained in a freeze lining of solidified slag to prevent refractory damage and ensure feasible furnace life. This makes the process an interesting and challenging one to operate and control. The study focused on interactions between the freeze lining and slag bath. A mathematical model was developed to describe heat transfer, solidification and melting in the freeze lining and furnace wall. This model was incorporated into another model to yield a dynamic simulation-type model of the entire smelting furnace process. Simulation experiments with the models aimed to study the dynamic response of the freeze lining to changes in power input, slag composition, and operating parameters. Due to confidentiality considerations, it was not possible to incorporate industrial data for comparison into the study. Regardless of this, the results still remain useful to practitioners when considering the process aspects that were investigated.

This study provides a mathematical model of T7 RNA polymerase (T7 RNAP) kinetics under in vitro conditions targeted at application of this model to simulation of dynamic transcription performance. A functional dependence of transcript synthesis rate is derived based on: (a) essential reactant concentrations, including T7 RNAP and its promoter, substrate nucleotides, and the inhibitory byproduct inorganic pyrophosphate; (b) a distinction among vector characteristics such as recognition sequences regulating transcription initiation and termination, respectively; and (c) specific properties of the nucleotide sequence including both transcript length and nucleotide composition. Inactivation kinetics showed a half-life of T7 RNAP activity of 50 min under the conditions applied in vitro using the isolated enzyme. Model parameters and their precision are estimated using dynamic simulation and nonlinear regression analysis. The particular novelty of this model is its capability to incorporate linear genomic sequence information for simulation of nonlinear in vitro transcription kinetics. ©

Magnetorheological (MR) uids represent a class of smart materials whose rheological properties change in response to the application of a magnetic eld. These uids typically consist of small ( m) magnetizable particles dispersed in a non-magnetic carrier uid that generally contains additives such as surfactants and anti-wear agents 1]. Due to such additives, there is an outer non-magnetic layer on the particles that keeps them from touching. The goal of this paper is to study the e ective magnetic behavior of an MR composite as a function of the interparticle distance. To this end, we present and employ a model for the e ective magnetic properties of MR uids with periodic microstructure that is based on the theory of homogenization. Finally, we discuss an interpolating formula for the e ective permeability of MR uids as an extension of the work of Keller 3] and Doyle 4].

This paper presents a new design algorithm for the decentralized output feedback control problem of largescale interconnected systems. A decentralized estimated state feedback controller and a decentralized observer are designed for each subsystem, based on linear matrix inequalities (LMIs). Sufficient conditions for the synthesis of feedback action are provided, under which the proposed controllers and observers can achieve robust stabilization of the overall large-scale system. An attractive feature of the proposed scheme is that it guarantees connective stability of the overall system, and requires no intersubsystem communication. The controller design is evaluated on a natural circulation drum boiler, where the nonlinear model describes the key dynamical properties of the drum, the risers, the downcomers and the turbine-generator unit. The linearized system has two poles at origin, one associated with water dynamics and the other with generator dynamics. Simulation results show the effectiveness of the proposed control against instabilities following sudden load variations. The control is also effective for steady state operation.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

This report documents the results of Phase II of a three phase research program to develop and validate improved methods to model the cognitive behavior of nuclear power plant (NPP) personnel. In Phase II a dynamic simulation capability for modeling how people form intentions to act in NPP emergency situations was developed based on techniques from artificial intelligence. This modeling tool, Cognitive Environment Simulation or CES, simulates the cognitive processes that determine situation assessment and intention formation. It can be used to investigate analytically what situations and factors lead to intention failures, what actions follow from intention failures (e.g., errors of omission, errors of commission, common mode errors), the ability to recover from errors or additional machine failures, and the effects of changes in the NPP person-machine system. The Cognitive Reliability Assessment Technique (or CREATE) was also developed in Phase II to specify how CES can be used to enhance the measurement of the human contribution to risk in probabilistic risk assessment (PRA) studies. The results are reported in three self-contained volumes that describe the research from different perspectives. Volume 1 provides an overview of both CES and CREATE. Volume 2 gives a detailed description of the structure and content of the CES modeling environment and is intended for those who want to know how CES models successful and erroneous intention formation. Volume 3 describes the CREATE methodology for using CES to provide enhanced human reliability estimates. Volume 3 is intended for those who are interested in how the modeling capabilities of CES can be utilized in human reliability assessment and PRA.

We present a novel framework for converting animated 3D shape sequences into compact and stable cage-based representations. Given a raw animated sequence with one-to-one point correspondences together with an initial cage embedding, our algorithm automatically generates smoothly varying cage embeddings which faithfully reconstruct the enclosed object deformation. Our technique is fast, automatic, oblivious to the cage coordinate system, provides controllable error and exploits a GPU implementation. At the core of our method, we introduce a new algebraic algorithm based on Maximum Volume Sub-matrices (maxvol) to speed up and stabilize the deformation inversion. We also present a new spectral regularization algorithm that can apply arbitrary regularization terms on selected sub-parts of the inversion spectrum. This step allows to enforce a highly localized cage regularization, guaranteeing its smooth variation along the sequence. We demonstrate the speed, accuracy and robustness of our framework on various synthetic and acquired data sets. The benefits of our approach are illustrated in applications such as animation compression and post-editing.

Water is a fundamental human resource and its scarcity is reflected in social, economic and environmental problems. Water used in human activities must be treated before reusing or returning to nature. This treatment takes place in wastewater treatment plants (WWTPs), which need to perform their functions with high quality, low cost, and reduced environmental impact. This paper aims to identify failures in real-time, using streaming data to provide the necessary preventive actions to minimize damage to WWTPs, heavy fines and, ultimately, environmental hazards. Convolutional and Long short-term memory (LSTM) autoencoders (AEs) were used to identify failures in the functioning of the dissolved oxygen sensor used in WWTPs. Five faults were considered (drift, bias, precision degradation, spike and stuck) in three different scenarios with variations in the appearance order, intensity and duration of the faults. The best performance, considering different model configurations, was achieved by Convolutional-AE.

This work focuses on the dynamic modeling of a flexible robotic manipulator with two flexible links and two revolute joints, which rotates in the horizontal plane. The dynamic equations are derived using the Newton-Euler formulation and the finite element method, based on elementary beam theory. Computer simulation results are presented to illustrate this study. The dynamic model becomes necessary for use in future design and control applications.

As distributed energy resource (DER) projects grow in popularity, there has been little focus on their potential to influence the dynamic stability of a transmission system. If implemented in large enough numbers, DER equipment may feasibly be leveraged to provide ancillary services such as spinning reserve, system inertia, or system stabilization. To determine the potential impacts of DER on future transmission grid stability, dynamic models of DER load combinations were created, reduced in order, and scattered throughout central and southem Califomia within an existing Western Systems Coordinating Council (WSCC) dynamic model. Evaluation of the composite WSCC-DER dynamic model allows correlations to be drawn between various DER properties and the transmission grid stability. Key find- ings show that increasing DER inertia tends to destabilize the transmis- sion system. The cause of this counterintuitive relationship requires further study but likely is related to the high impedance separating the DER from the transmission grid.

The ideal Stirling cycle have two constant volume processes for heat regeneration and two constant temperature processes for heat addition and removal. These processes are sequenced and timed to create mechanical work. The main components responsible for these time-based processes are the working piston and displacer. Therefore, their position, motion and timing are vital for the engine’s operation and its output performance. The drive mechanism of a Stirling engine is responsible for the working piston and displacer’s motion, timing and extracting mechanical work. A crank-slider mechanism is commonly used as the drive mechanism but it provides near sinusoidal motion to the components. This limits net heat transfer to the internal working fluid and consequently limits mechanical work. To increase net heat transfer and mechanical work of a Stirling engine, the use of non-sinusoidal working piston and displacer motion was proposed through the use of a novel cam-drive mechanism. A cam is a classical, simple and proven technology as it has been used in many applications and machines. As a cam-drive mechanism to extract mechanical work, it can be designed for various types of working piston and displacer non-sinusoidal motion as well as integrating dwell. An experimental approach was used to assess the capability of the cam-drive mechanism. A gamma configuration medium temperature difference Stirling engine was developed with a cam-drive mechanism which has a two-sided face grooved radial cam flywheel operating with roller oscillating cam followers. Various motions for the working piston and displacer was designed and tested. Kinematic analysis for this mechanism ensures smooth, low noise and low vibrations operation during the design stage. Through the use of a data acquisition system, thermal efficiency was found to improve 36% in comparison with the benchmarked sinusoidal working piston and displacer motion. This paper documents the design, fabrication and experience in using a cam-drive mechanism in a Stirling engine.

We develop a statistical and thermodynamic formulation of the Absolute Medium (AM), complementing its deterministic continuum dynamics. The AM is a discrete elastic medium with a fundamental length L fund and a maximum strain ε max. We define microstates as configurations of the discrete AM lattice and introduce a coarse-grained entropy functional that measures the number of microrealizations consistent with given macroscopic fields (ρ, u i , ε ij). The Unity of Persistence (UP) condition U ≥ 1 is shown to be equivalent to an entropy bound: configurations with U < 1 have entropy that cannot be sustained under the causal redistribution capacity. Relaxation and saturation are reinterpreted as irreversible processes that increase entropy toward a maximum consistent with the UP constraint. The arrow of time emerges from the entropic drive toward admissible macro-states. This statistical formulation provides a deeper justification for UP as a selection principle and connects AM to information theory and maximum entropy principles. Although not required for practical simulations, it completes the conceptual foundations of the framework.

We describe an approach and our experiences in applying federated simulation techniques to create large-scale parallel simulations of computer networks. Using the federated approach, the topology and the protocol stack of the simulated network is partitioned into a number of sub-models, and a simulation process is instantiated for each one. Runtime infrastructure software provides services for interprocess communication and synchronization (time management). We first describe issues that arise in homogeneous federations where a sequential simulator is federated with itself to realize a parallel implementation. We then describe additional issues that must be addressed in heterogeneous federations composed of different network simulation packages, and describe a dynamic simulation backplane mechanism that facilitates interoperability among different network simulators. Specifically, the dynamic simulation backplane provides a means of addressing key issues that arise in federating different network simulators: differing packet representations, incomplete implementations of network protocol models, and differing levels of detail among the simulation processes. We discuss two different methods for using the backplane for interactions between heterogeneous simulators: the cross-protocol stack method and the split-protocol stack method. Finally, results from an experimental study are presented for both the homogeneous and heterogeneous cases that provide evidence of the scalability of our federated approach on two moderately sized computing clusters. Two different homogeneous implementations are described: Parallel/Distributed ns (pdns) and the Georgia Tech Network Simulator(GTNetS). Results of a heterogeneous implementation federating ns with GloMoSim are described. This research demonstrates that federated simulations are a viable approach to realizing efficient parallel network simulation tools.

Residential kitchens are high-energy spaces, serving as both functional cooking areas and central zones for household energy use and thermal dynamics. This study investigates energy consumption and thermal comfort in a typical residential kitchen located in northeastern Algeria, which are high-energy-use areas with unique thermal challenges in summer. To achieve the study's objectives, we focused on three main investigative steps. First, we assessed air temperature, humidity, and wind velocity at different points within the kitchen to identify areas with significant microclimate variation, data crucial for optimizing ventilation and cooling systems. Second, we evaluated the energy use and heat output of kitchen appliances to identify energy-intensive devices and develop strategies for reducing overall heat load. Third, we used thermal imaging to visualize heat distribution, enabling us to analyse spatial heat spread, improve heat dissipation, and reduce hotspots. The findings reveal that microclimate variations in the kitchen, influenced by cooking schedules and appliance use, create significant thermal discomfort due to heat accumulation and limited ventilation. Heat retention from envelope materials and appliances amplifies indoor temperatures, particularly in the evening. Recommendations include natural ventilation solutions, reflective materials, and thermal insulation to enhance comfort and energy efficiency.

The well-investigated size-frequency distributions (SFD) for lunar craters can be used to estimate the SFD for projectiles that formed craters both on terrestrial planets and on asteroids. Our results suggest these distributions may have been relative stable over the past 4 G.y. The derived projectile SFD is found to have a shape that is similar to the SFD of main-belt asteroids as compared with the astronomical observations (Spacewatch asteroid data, Palomar-Leiden survey, IRAS data) and in situ images obtained by space missions. This result suggests that asteroids (or, more generally, collisionally evolved bodies) are the main component of the family of impactors striking the terrestrial planets.

In order to introduce solid obstacles into flows, several different methods are used, including volume penalization methods which prescribe appropriate boundary conditions by applying local forcing to the constitutive equations. One well known method is Brinkman penalization, which models solid obstacles as porous media. While it has been adapted for compressible, incompressible, viscous and inviscid flows, it is limited in the types of boundary conditions that it imposes, as are most volume penalization methods. Typically, approaches are limited to Dirichlet boundary conditions. In this paper, Brinkman penalization is extended for generalized Neumann and Robin boundary conditions by introducing hyperbolic penalization terms with characteristics pointing inward on solid obstacles. This Characteristic-Based Volume Penalization (CBVP) method is a comprehensive approach to conditions on immersed boundaries, providing for homogeneous and inhomogeneous Dirichlet, Neumann, and Robin boundary conditions on hyperbolic and parabolic equations. This CBVP method can be used to impose boundary conditions for both integrated and non-integrated variables in a systematic manner that parallels the prescription of exact boundary conditions. Furthermore, the method does not depend upon a physical model, as with porous media approach for Brinkman penalization, and is therefore flexible for various physical regimes and general evolutionary equations. Here, the method is applied to scalar diffusion and to direct numerical simulation of compressible, viscous flows. With the Navier-Stokes equations, both homogeneous and inhomogeneous Neumann boundary conditions are demonstrated through external flow around an adiabatic and heated cylinder. Theoretical and numerical examination shows that the error from penalized Neumann and Robin boundary conditions can be rigorously controlled through an a priori penalization parameter η. The error on a transient boundary is found to converge as O (η), which is more favorable than the error convergence of the already established Dirichlet boundary condition.

The integration of renewable energy sources (RESs), such as wind and solar, introduces significant uncertainties into power system operations, complicating Available Transfer Capability (ATC) assessment. A key factor in ATC determination, the Transmission Reliability Margin (TRM), accounts for uncertainties like load variations, generation fluctuations, and network dynamics. The traditional deterministic TRM methods often fail to capture the stochastic nature of modern grids, leading to inaccurate estimations. This paper reviews the TRM assessment methodologies, emphasizing probabilistic approaches that enhance accuracy in high-RES environments. It explores adaptive statistical techniques, such as rolling window analysis, for dynamic TRM computation. Key challenges, emerging trends, and potential solutions are discussed to support the development of robust ATC modeling frameworks for secure and efficient renewable energy integration.

All dwellings in the UK are required to have an Energy Performance Certificate (EPC) when sold or let, giving potential owners or tenants information on the cost and associated CO 2 emissions of heat and power. The Scottish traditional construction of solid stone walls tends to get unfavourable EPC ratings, leading to a perception that 'old is cold': this paper uses alternative calculation methods to question that perception. The difference in results from steady-state and dynamic energy assessment methods is investigated for a dwelling with high thermal mass. The study focuses on modelled data and concludes that SAP 2009's monthly assessment estimates lower energy use and therefore gives a more favourable EPC rating than the annually based RdSAP 2005; and further that the application of dynamic simulation models may not be the optimum solution to further understanding energy efficiency of this type of dwelling.

An adaptive high order discontinuous Galerkin (DG) scheme for performing beam dynamics simulations is presented. We elaborate on hand p-adaptations, the former modifying the actual size of computational elements and the latter the dimension of the associated approximation space. The efficiency and stability of the adaptation techniques are emphasized. The scheme is applied in order to perform hp-adaptive beam dynamics simulations. We compare the results with the analytical solution and demonstrate that the adaptive scheme requires significantly less computational resources for obtaining a certain accuracy.

An adaptive high order discontinuous Galerkin (DG) scheme for performing beam dynamics simulations is presented. We elaborate on handp-adaptations, the former modifying the actual size of computational elements and the latter the dimension of the associated approximation space. The efficiency and stability of the adaptation techniques are emphasized. The scheme is applied in order to performhp-adaptive beam dynamics simulations. We compare the results with the analytical solution and demonstrate that the adaptive scheme requires significantly less computational resources for obtaining a certain accuracy.

We present the results of extensive beam dynamic simulations that have been carried out in order to study the non-linear effects of an electromagnetic elliptical wiggler, presently under construction for ELETTRA, using different symplectic tracking methods implemented in the codes BETA and RACETRACK.

It is widely accepted that the Accelerator Driven System (ADS) is one of the most promising technical approach to solve the problem of the nuclear wastes, a potential threaten to the sustainable development of the nuclear fission energy. An ADS study program was approved by Chinese Academy of Sciences at 2011, which aims to design and built an ADS demonstration facility with the capacity of more than 1000 MW thermal power within the following 20 years. The 15 MW driver accelerator will be designed and constructed by the Institute of High Energy Physics (IHEP) and Institute of Modern Physics (IMP) of China Academy of Sciences. This linac is characterized by the 1.5 GeV energy, 10mA current and CW operation. It is composed by two parallel 10 MeV injectors and a main linac integrated with fault tolerance design. The superconducting acceleration structures are employed except the RFQ. In this paper the general considerations and the beam dynamics design of the driver accelerator will be presented.

This paper presents an integrated conceptual model describing the early evolution of the Earth-Moon system. The framework combines tidal dissipation, angular momentum transfer, debrissdisk dynamics following the giant impact, and a possible early magnetospheric interaction phase between Earth and the Moon. By combining physical reasoning with simplified dynamical modeling, the work proposes a coherent description of the transition from the postsimpact debris disk to the present Earth-Moon orbital configuration.

A three-dimensional time-dependent parallel particlein-cell framework has been developed to model complex accelerator systems. This framework has been designed based on object-oriented methodology using a layered structure. The layer-based object-oriented software design helps to encapsulate both the details of the physical application and its parallel implementation and gives the program good maintainability and extensibility. The new framework is currently being applied to the study of the LEDA beam halo experiment at the Los Alamos National Laboratory. Using the new framework running on a parallel supercomputer we can simulate, with high resolution, multiple bunches propagating and merging through the LEDA system, including the effects of interbunch and intrabunch 3D space-charge forces. Such high resolution multi-bunch simulation is beyond the capability of current serial beam dynamics codes.

Plans for the RHIC luminosity upgrade call for an electron cooling system that will place substantial demands on the energy, current, brightness, and beam quality of the electron beam. In particular, the requirements demand a new level of fidelity in beam dynamics simulations. New developments in MARYLIE/IMPACT have improved both the space-charge computations for beams with large aspect ratios and the beam dynamic computations for rf cavities. We present the results of beam dynamics simulations that include the effects of space charge and nonlinearities, and aim to assess the tolerance for errors and nonlinearities on current designs for a super-conducting ERL.

New generation accelerator-based X-ray light sources require high quality beams with high average brightness. Normal conducting L-and S-band photoinjectors are limited in repetition rate and D-C (photo)injectors are limited in field strength at the cathode. We propose a low frequency normal-conducting cavity, operating at 50 to 100 MHz CW, to provide beam bunches of up to the cavity frequency. The photoinjector uses a re-entrant cavity structure, requiring less than 100 kW CW, with a peak wall power density less than 10 W/cm 2 . The cavity will support a vacuum down to 10 picoTorr, with a load-lock mechanism for easy replacement of photocathodes. The photocathode can be embedded in a magnetic field to provide correlations useful for emittance exchange. Beam dynamics simulations indicate that normalized emittances smaller than 1 mm-mrad are possible with gap voltage of 750 kV, with fields up to 20 MV/m at the photocathode, for 1 nanocoulomb charge per bunch after acceleration and emittance compensation. Long-bunch operation (10's of picosecond) is made possible by the low cavity frequency, permitting low bunch current at the 750 kV gap voltage.

The Advanced Photoinjector Experiment (APEX) is part of the Next Generation Light Source (NGLS), a proposed soft x-ray FEL concept being studied at LBNL. The requirements for the beam delivered to the FELs pose restrictions on the beam parameters at the injector. In addition, different modes of operation of the machine may pose different requirements on the beam. In order to optimize the performance of the injector, a genetic multiobjective algorithm has been used. A genetic algorithm is used because of the inherent complexity of the beam dynamics at the energy range in question (0-30 MeV) and the large number of parameters available for optimization. On the other hand, the multiplicity of requirements on the beam, which include beam emittance, beam pulse length, energy chirp, as well as pulse shape and peak current, leads to a multiobjective approach for the optimization technique. In this paper, we present the status of the optimization simulations, using the ASTRA particle-in-cell code. A number of different solutions for a range of bunch charges are presented and the resulting transport solutions are compared to each other and the requirements of the downstream sections of the accelerator.