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The use of surrogate models for forecasting dynamic behaviors of processes is a promising approach for optimizing process operation and control. This study aims to utilize the powerful prediction capabilities of deep learning-based dynamic surrogate models (DSMs) for fault detection in non-stationary processes, taking into account the impact of control actions on faults. A novel control-aware fault detection approach, utilizing data-driven dynamic surrogate modeling of closed-loop controlled processes, is proposed to detect potential faults under various control actions and operating conditions. DSMs for both one-step and multi-step ahead prediction are developed and combined to detect various types of faults, based on predictions and residuals while considering control effects. High-fidelity dynamic simulations are used to build first principles-based closed-loop process models and generate data under various operating conditions to train the DSMs. Deep learning methods such as long short-term memory and gated recurrent units are employed for dynamic surrogate modeling, and their performance is compared to select the optimal method. The proposed approach is demonstrated through two case studies using a continuous stirred tank reactor and a distillation column with an advanced control structure. The results consistently demonstrate that the approach can achieve both accurate fault detection and reliable false alarm avoidance under different dynamic operating conditions and faulty situations with varying severities and fault types. [ABSTRACT FROM AUTHOR]

• A dynamic model of civil aircraft air-cycle refrigeration system was developed • A dynamic solution method was introduced for dynamic mass transfer solution. • A near-logarithm heat transfer temperature difference function is presented. • A pressure-flow decoupling method is presented to obtain ACM pressure parameters. Dynamic simulation model of air-cycle refrigeration system s in civil aircrafts is essential for revealing the operation mechanism during flight process. In the present study, a dynamic model of three-wheel air-cycle refrigeration system was developed. A near-logarithm heat transfer temperature difference function is utilized to improve the stability of the heat transfer solution. A dynamic solution method based on continuity equation and theorem of momentum was presented as the framework of the dynamic mass transfer solution. A pressure-flow decoupling method is presented to solve the dynamic pressure in the high-pressure zone, resolving the absence of key pressure parameters. The model has been validated based on experimental data, with a pack discharge temperature deviation of 0.05K. Dynamic simulations have been conducted with actual flight data to obtain transient performance under airborne condition. In the takeoff and landing phase, the drastic change in the environment results in low discharge temperature, endangering the condenser with icing risk, which can be avoided by enabling the TCV. In the cruise phase, the discharge temperature slightly exceeds the upper limit for a couple of minutes. The optimization by slightly extending the length of heat exchanger channels succeeded in eliminating the excessive discharge temperature with minimal side effects. [ABSTRACT FROM AUTHOR]

Rectisol wash process(RWP) is a common process in coal chemical purification unit. However, the CO 2 product gas and tail gas in the RWP carries volatile organic methanol, which must be controlled to meet the environmental protection requirements. This work develops a steady and dynamic model for the process of water washing tower(WWT) by Aspen Plus, which is used in Rectisol wash tail gas treatment. The effects of the theoretical stage number(TSN) and desalting water flow rate(FR dw) of the washing tower on the methanol concentration in tail gas(c MET) are studied through sensitivity analysis. The optimized TSN and FR dw of WWT are 16 stages and 15 t/h, respectively. The c MET is 4.1 mg/Nm3 under the optimal condition. The internal structure of WWT is optimized. The design of the WWT is verified by the hydraulic results and dynamic process simulation. The results help to efficiently and conveniently implement the control of volatile organic methanol from RWP. [ABSTRACT FROM AUTHOR]

• Solar distiller performance is investigated using novel detailed dynamic model. • Performance of wood side walls solar distiller is higher than that of glass ones. • Largest portion of energy loss from the solar distiller is from glass cover. • Useful portion of the distiller energy represents 39.6% of the incident energy/ • Daily energy reflected, storage, and loss represent 22, 2.9, and 35.5%, respectively. A novel transient detailed mathematical model is constructed and presented for simulation of the single slope solar still performance. The model considers all the still walls and regions including the humid air zone. Moreover, the still walls' dimensions, areas, and material properties besides the energy rate and heat exchange by convection, radiation, conduction, and condensation inside and outside the still are considered. This model estimates the temperatures, detailed energy losses and gains, and energy exchange of the still zones and walls beside still productivity and efficiency. The impact of side walls' materials; glass or wood on its performance is considered. The model is programmed and solved using MATLAB software and validated via experimental work. The results are presented under climate conditions of Assiut city, Egypt. The outcomes show that the present still model results accurately accord with the experimental results. The daily productivity per square meter of the basin area of the wooden side walls and the glass side walls stills are about 4.12 and 2.22 kg/m2, respectively. The glass cover energy loss represents the largest portion loss from the still. Besides, the convection heat loss from the humid air to the still walls is greater than that of the radiation loss and the latter from still walls to the ambient is greater than that of the convection. The daily useful portion of the incident solar energy is 39.6%, while the daily energy reflected, stored, and lost outside the still represent 22%, 2.9%, and 35.5%, respectively. [ABSTRACT FROM AUTHOR]

This study proposes a novel, eco-friendly design for a deep-sea floating mining vehicle multi-body system (DFMVMS), incorporating a floating mining vehicle (FMV) as its central mining apparatus. The comprehensive system architecture encompasses a surface mother ship, a main pipe cable, an ore transit station, an umbilical pipe cable (UPC), and the FMV, engineered for deep-sea extraction activities while preserving benthic ecosystems. To investigate the interactions among the multi-body system's components and ascertain the collective motion dynamics during operational states, initial steps involved developing mathematical models for each individual component. Subsequently, a holistic model for the entire DFMVMS was formulated by integrating these component models via coupling boundary conditions, with the model's accuracy subsequently affirmed. Analytical scenarios, including three foundational motion states of the FMV, were structured to explore the influence of FMV dynamics on the DFMVMS's overall behaviour. Moreover, specific operational scenarios were tailored to reflect two principal functions of the DFMVMS—production and transfer. The simulation results significant interplay among the movements of the system's components, highlighting UPC tension as a critical consideration in devising transfer routes. • Introduced an eco-friendly deep-sea mining system with a floating vehicle as the main equipment. • Developed a dynamic model for this complex multi-body system, including a transit station. • Validated the model through simulations of three fundamental floating vehicle operations. • Designed and simulated two real-world operational scenarios, providing practical insights. [ABSTRACT FROM AUTHOR]

Dynamic simulation is a powerful tool for accurately evaluating the thermal demands of buildings and assessing the impact of energy refurbishment actions on their final consumption. Conversely, semi-stationary models are widely adopted in commercial applications for its simplified approach, which reduce calculation times, resulting in standardized results showing a certain deviation with respect to the real energy This paper presents the energy and economic comparison between the dynamic simulation and semi-stationary approaches for the calculation of primary energy demand of residential buildings. The semi-stationary method, used by the legislation to calculate the buildings energy label, is based on an energy performance parameter, not representative of the real energy demand. Conversely, an approach based on dynamic simulation provides a more reliable estimation of the primary energy demand. The main novelty of this paper is to numerically prove that the energy and economic savings calculated by means of software based on the current legislation may be overestimated. In this work, the dynamic simulation of the building-plant system is performed by TRaNsient SYstem Simulation (TRNSYS) program. Each building apartment is divided in thermal zones, where the internal heat gains are defined in detail. The semi-stationary simulation of the building-plant system is performed according to the Italian standard UNI TS 11300. The models allow one to evaluate the yearly primary energy demand, along with the energy bill and CO 2 emissions. A specific case study is developed for a residential building located in Naples (Italy). The models are used to calculate the building energy demand for several scenarios, considering different thermal transmittances of the building elements. The results show that the semi-stationary method overestimates of primary energy saving, equal to 64.7 %, with respect to the one calculated with the dynamic approach, equal to 43.2 %. • Semi-stationary and dynamic simulations were compared for residential buildings. • Critical evaluation of energy and economic savings due to the building refurbishment. • Primary energy savings of 65 % and 43 % by semi-stationary and dynamic simulation. • Dynamic simulation is needed within the legal frame of energy efficient buildings. [ABSTRACT FROM AUTHOR]

In this study, two processes of predictive model combining dynamic simulation and regression model were presented. First, (1) the demand forecasting process defined in this study is a method of predicting energy consumption based on the simulated energy consumption of a target building, and (2) the energy saving process is a method of setting an energy reduction target based on the predicted energy consumption and providing energy saving measures to achieve the target. Specifically, there are two functions based on the regression models which are predicting actual energy consumption by inputting the energy consumption simulation data, and inversely inputting the actual energy consumption and deriving the corresponding simulation conditions. As a result of predicting building energy consumption through the demand forecasting process, the performance in the heating season showed CV-RMSE was 14.622%, and in the cooling season CV-RMSE was 5.877%. In addition, in the case study using the energy saving process, it was possible to derive the heating and cooling set temperature for 5% energy saving as an energy saving method by using weather forecast data. • Demand forecasting and energy saving of buildings. • Regression model-based process between simulation-based predictions and actual energy consumption. • Two processes combining TRNSYS and DNN model to ensure building energy management efficiency. [ABSTRACT FROM AUTHOR]

• We conduct 61 simulations to select a preferred model using the grid search method. • We constrain dynamic simulations with geodetic, seismic, and geological observations. • The 2022 Menyuan earthquake nucleated vigorously and could grow into a large event. • The fault bend and stepover act as stress barriers and terminate the rupture early. The 2022 Mw 6.6 Menyuan earthquake, which caused unexpectedly large surface offsets (about 2.6–3.5 m) relative to the moment magnitude of this event, is one of the best-recorded strike-slip events in the northeastern Tibetan plateau. Although previous studies have revealed many kinematic features of this event, the mechanism and rupture dynamic characteristics underlying unexpectedly large surface dislocations need to be clarified. In this study, based on the grid search method, we conducted 61 dynamic rupture simulations considering terrain relief to screen out a preferred dynamic model that fits the geodetic, seismic, and geological observations well. The results show that the average stress drop of the nucleation part is relatively high (11 MPa), which could provide high initial rupture energy and give this event a chance to develop into a large earthquake. However, the rupture propagating eastward is slowed and terminated by two consecutive fault bends of about 10° each, and the westward propagating one might concentrate at a shallow depth (< 3 km) on the south secondary fault after it jumps over the stepover. These results imply that the complex fault geometry (the fault bend and stepover) might terminate the rupture early so that the observed magnitude of this event (Mw 6.6) is smaller than the estimated magnitude (Mw 7.1–7.2) based on the surface offsets. Our study again shows that, due to advances in computational power and observations (coverage and quality), physics-based dynamic rupture simulations have entered an era where it is possible to fit the observed data well, which is vital for further understanding the mechanisms of earthquakes. [ABSTRACT FROM AUTHOR]

• Dynamic simulation model is able to predict real column behavior during start-up. • New start-up strategy for the pilot multiple dividing wall column is proposed. • Start-up time of the column strongly depends on the selected strategy. • Start-up of the pilot multiple dividing wall column is possible within few hours. Multiple dividing wall columns are a promising extension of the concept of dividing wall columns offering energy savings of up to 55 % compared to conventional distillation sequences for four products. This paper presents the first systematic study on the start-up of a multiple dividing wall column. The study aims to develop a start-up strategy for the first pilot multiple dividing wall column worldwide commissioned at Ulm University. The start-up process is investigated using a dynamic simulation model that facilitates the investigation of different start-up strategies and the influence of different factors on the start-up process. Based on these dynamic simulations a viable start-up procedure for the column is found. Through improvements to the procedure a significantly shortened start-up process is achieved. The dynamic response of the column shows that the cold and dry plant is able to reach the desired operating point within few hours. Simulation results are confirmed with experimental data from the pilot column. [Display omitted] [ABSTRACT FROM AUTHOR]

The deepwater S-lay pipeline maintains high tension, bending moment, and stress in the overbend section, exhibiting substantially dynamic responses due to pipe-stinger roller interactions. This paper presents a refined S-lay pipeline model capable of accurately describing the forces and deformations on the pipeline section. In this model, the pipeline is discretized into beam particles and beam elements using the vector form intrinsic finite element (VFIFE) method. Meanwhile, the equivalent beam particle technique is developed to account for both the local forces and deformations of the pipeline as well as its overall static and dynamic responses. Through program coding, a dynamic time-domain simulation was accomplished for a 12-inch pipeline being laid to a water depth of 1000 m to provide a detailed illustration of the S-lay modeling process. Furthermore, dynamic behaviours of the pipeline in the overbend were systematically investigated under various groups of the pipe diameter and the stinger roller spacing. The results indicate that the stress and deformation on the upper section of the pipeline are more significant than those on the lower section. The equivalent beam particle method extends the capabilities of the VFIFE for the detailed analyses of local dynamic behaviours of deepwater S-lay pipelines. • A refined VFIFE model of deepwater S-lay pipeline is proposed to investigate the overall and local internal forces and deformations. • The equivalent beam particle technique with the extension of the VFIFE method is developed to calculate pipeline stress and strain in the overbend section. • The accuracy and effectiveness of the refined VFIFE model are fully verified. • Significant differences of the pipeline local stress and strain between the upper and lower sections are observed. • The effects of pipe diameter and stinger roller spacing on the pipeline section behaviours are identified. [ABSTRACT FROM AUTHOR]

Power electronics converters have been widely deployed in modern power systems in different voltage levels. The complex operation characteristics of power converters, which combine different control modes and various current saturation states, are also significantly changing the power systems' behavior in fault conditions. The objective of this paper is to develop a steady-state short-circuit calculation solver for power systems with power electronics without the need of detailed dynamic models. In particular, the steady-state operation equations related to the converter control are included in the system formulation. An extended Newton–Raphson (NR) solver is proposed to compute the short-circuit equilibrium point that considers converters' operation limits. Also, an iterative algorithm is presented in order to efficiently identify the current saturation states of power converters under a specific short-circuit fault scenario. Case studies have been presented with several power systems with voltage source converters (VSCs). Dynamic simulations are included to validate the accuracy of the proposed methodology. • This paper presents an extended Newton–Raphson solver to cope with the new formulation considering power converters' operation. • An iterative algorithm that identifies the current saturation state of a converter in a specific fault scenario. • The proposed methodology has been implemented in several benchmark systems with VSCs. simulation results. [ABSTRACT FROM AUTHOR]

This paper investigates the nonlinear dynamics and control for three-dimensional retargeting maneuver of a flexible multi-tethered satellite formation at the sun-earth L 2 libration point. In Hill's problem, a fundamental modeling strategy is adopted to develop two dynamic models, a flexible one for dynamic simulation and a rigid one for control design. Both the flexibility of tethers and the attitude motions of satellites have been incorporated into the system dynamics. Not limited to the system under consideration, this flexible model could be generally exploited to describe multi-tethered satellite formation systems with arbitrary configurations. Besides, a nonlinear model-predictive control law for the retargeting problem of concern is developed to achieve the desired attitude of the system. The attitude control of the satellites is performed during retargeting process based on optimal control using a switching on–off method. For the ease of tracking an optimal trajectory of tether libration states and control input, an adaptive gain control law is proposed to retarget the flexible system. Finally, numerical case studies have been carried out to evaluate the dynamic behaviors of the system and to demonstrate the effectiveness of the proposed retargeting controller. [ABSTRACT FROM AUTHOR]

• A leg-type asteroid probe landing cushioning device is proposed based on electromagnetic damping. • The vertical landing speed and landing tilt angle will affect the cushioning characteristics. • The horizontal movement direction and the landing tilt direction have a coupling effect on the landing dynamics. • Soft landing media will cause the footpad to collide and bounce on the surface, thereby increasing the cushioning time. In-situ scientific exploration is of great significance to asteroid exploration, and resource development and utilization. The asteroid surface landing cushioning is the basis of in-situ scientific exploration of asteroids. Therefore, a leg-type asteroid landing cushioning device is proposed based on the principle of electromagnetic damping. A dynamic simulation model is used to study the cushioning dynamics of the cushioning device in a microgravity environment. For the proposed landing cushioning device, the simulation investigates the influence of vertical landing speed and landing vertical tilt angle on the dynamic characteristics and landing stability. The dynamics simulation method is also adopted to investigate the influence of the landing horizontal tilt angle and the horizontal movement direction on the landing stability of the three-legged asteroid probe. The horizontal movement direction and the landing horizontal tilt angle have a coupling effect on the landing cushioning dynamics. Finally, based on the developed simulation device of asteroid microgravity environment, landing cushioning experiments are conducted to investigate the influence of soft and hard landing media on the cushioning process and verify the feasibility of the landing cushioning device. The comparison and analysis of the experimental results and the simulation results verify the accuracy of the landing cushioning dynamics simulation method. [ABSTRACT FROM AUTHOR]

Air-cooled low-temperature proton exchange membrane fuel cell stack applied with metallic bipolar plate is considered as a promising power source for an unmanned aerial vehicle. This paper presents a coupled electrochemical thermal model for simulating its dynamic characteristic. The impact of the applied metallic bipolar plate on the stack thermal balance is considered; an environmental model estimating atmospheric temperature and pressure variations with altitude is included. Our theoretical analysis shows that with altitude increased from 0m to 4000m, the output electric power declined rate is 4.7–6.5% at the current density of 400–800 mA cm−2. To avoid severe stack degradation due to high stack operating temperature, minimum air stoichiometric ratio is required for maintaining stack thermal balance. When the altitude increases from 0 to 4000m, the minimum required air stoichiometric ratio decreases from 110 to 22 at the current density of 800 mA cm−2. [ABSTRACT FROM AUTHOR]

Heat–power decoupling is a key issue to be addressed for the combined heat and power (CHP) unit to enhance its operational flexibility, and utilizing heat storage in district heating systems represents a viable approach. The widespread adoption of heat pumps to boost heating network also increases the complexity of managing heat storage, and the quantitative impact of heat storage has significant implications during operation. To this end, dynamic models of heating networks and heat pumps were developed. A metric, the maximum maintenance time, was established to quantitatively assess heat storage utilization. Dynamic simulations and performance analyses were conducted on a 330 MW CHP unit. The results indicate that by employing heat storage, the feasible maximum and minimum output power of the heating system can be increased by 20 MW and decreased by 45.5 MW, respectively. With the integration of a heat pump, these values can further increase by 9 MW and decrease by 158 MW, respectively, significantly enhancing the operational flexibility of CHP unit. • Dynamic models of CHP unit, heating networks and heat pump were developed. • A new index to evaluate the heat storage capacity that can be used is proposed. • Dynamic simulation and performance analysis were conducted with a 330 MW CHP unit. • The integration of heat pump can increase heat storage capacity for peak shaving. • The feasible minimum output power of the CHP unit can be decreased by 158 MW. [ABSTRACT FROM AUTHOR]

In this study, lignocellulose-derived aerogel (LA) with compression-rebound was synthesized from liquefied wood through sol-gel polymerization, aging and freeze-drying process. The results presented a gradual increase in the compressive strength, flexural strength, and maximum decomposition temperature of the LA sample with prolonged aging time from 3 to 10 h, demonstrating excellent elasticity and thermal stability. After more than 10 h, the bending strength began to decrease, indicating that the material's rigidity was greater than its elastic toughness at this time. A nonlinear viscoelastic constitutive model based on the Ogden function and parallel rheological framework showed very high correlation with experimental measurement results, and also demonstrated admirable mechanical properties. These predictions can provide an effective approach for the application of LA in buffer packaging. [Display omitted] • Lignocellulose-derived aerogels for buffer packaging was successfully obtained. • Appropriate aging time improved thermal stability and mechanical properties of LA. • High bending strength of 2.64 MPa at 50 % compression strain can be obtained. • LA-E4 achieved excellent compression rebound rate of 96.15 %. • A viscoelastic constitutive model for predicting mechanical behavior was established. [ABSTRACT FROM AUTHOR]

• The service life estimation of linear guideways can be done with damage accumulation. • A model-based condition monitoring of linear guideways is mandatory. • A vibration model of the linear guideway must consider all relevant elasticities. • A vibration model can be used to estimate the pitting size. • The pitting size progression can be used to estimate a remaining service life. The paper describes two novel calculation methods that can predict the service life of linear guideways more accurately than the conventional method. The first method is based on a linear damage accumulation in each rolling contact, which can take into account changing load cycles for a statistically based long-term remaining service life estimation. Since this statistically based estimation still has some inaccuracies, a second method is proposed that uses a dynamic simulation model of the linear guideway to perform a model-based condition monitoring. With this method, a more accurate damage-based prediction of the remaining useful service life can be made in the short term. The dynamic model takes into account both the elasticity of the Hertzian rolling contact and the elasticities of the carriage and rail depending on the dynamic rolling element circulation. The model also includes a simplified pitting model which allows the actual pitting size to be calculated by comparing the simulated vibration behaviour with the measured vibration behaviour. The calculated pitting propagation velocity is used to estimate the remaining useful service life. [Display omitted] [ABSTRACT FROM AUTHOR]

The increasing amount of Distributed Energy Resources (DERs) in Distribution Networks (DNs) has awakened the interest of system operators to represent how DERs will react to large disturbances. These units will respond according to the ride-through capability curves, the tripping logic settings, the local voltage magnitude, and frequency measurements. In this paper, we show the limitations of the well-known DER_A model and propose changes to represent better the ride-through capabilities and the tripping of a population of DER units. We also show the need for more than one aggregation in the same bus to represent the response of the old and modern DER technologies. To validate the new model, we run dynamic simulations of a Transmission Network (TN) and DNs with hundreds of DER units modeled in detail. The simulation results show that the proposed changes improve the representation of a population of DERs during low-voltage and low-frequency events. • Review of discrepancies between DER_A ride-through/trip logic and IEEE Std. 1547-2018. • New aggregate model for distributed energy resources with ride-through capabilities. • Validation of the new ride-through logic by comparing against disaggregated models. [ABSTRACT FROM AUTHOR]

• A plant-wide model is presented for continuous biomanufacturing benchmarking. • The model includes a tailored control strategy for dynamic simulation performance. • Realistic sensors and actuators consider measurement's noise and lag time. • Case study framework and examples are provided for user guidance. The pharmaceutical industry's shift towards biological therapeutics has led to a transition from conventional batch production to continuous manufacturing. This change highlights the crucial need for effective process monitoring and control strategies to ensure consistent product quality and stability. Open-source benchmark simulation models have become essential tools for refining these processes, offering a platform for testing research hypotheses. This study uses the production of Lovastatin as a case study for continuous biopharmaceutical production. A comprehensive dynamic model covering upstream and downstream components provides an integrated perspective of the production process. The study introduces a basic control system emphasizing realistic sensor and actuator integration to enhance simulation accuracy. It assesses the benchmark through open-loop and closed-loop simulations, offering an in-depth analysis of the KTB1 model's dynamic response and functionality. KTB1 represents a model-driven decision support tool that enables the evaluation of monitoring strategies, process design, process optimization, and control for biomanufacturing. [ABSTRACT FROM AUTHOR]

• The optical fiber coil with spool (OFCS) is a crucial tool for precise physics measurements. • To improve the seismic resistance of OFCSs in space applications, the vibration modes are thoroughly investigated through dynamic analysis, simulations, and experiments. • We establish a dynamic model of the OFCS based on the vibration transmission mechanism to characterize its vibration modes. • The vibration eigenfrequency and shapes are calculated under various conditions. • The experimental results validate the feasibility of the dynamic model and simulation, meanwhile, the discrepancies between the simulations and experiments are analyzed. • This study is the first of its kind to develop a comprehensive dynamic model for an OFCS, with simulations and experiments confirming its effectiveness. The optical fiber coil with spool (OFCS) is a crucial tool for precise physics measurements. To improve the seismic resistance of OFCSs in space applications, the vibration modes are thoroughly investigated through dynamic analysis, simulations, and experiments. We establish a dynamic model of the OFCS based on the vibration transmission mechanism to characterize its vibration modes. The vibration eigenfrequency and shapes are calculated and simulated under various conditions. The experimental results validate the feasibility of the dynamic model and simulation, meanwhile, the discrepancies between the simulations and experiments are analyzed. This study is the first of its kind to develop a comprehensive dynamic model for an OFCS, with simulations and experiments confirming its effectiveness. [ABSTRACT FROM AUTHOR]

Barocaloric refrigeration technology is a promising candidate for next-generation refrigeration technologies attributed to its eco-friendliness, high efficiency, and mechanical stability. To date, research in this field has predominantly focused on the exploration of solid-state refrigerants. However, the development of barocaloric systems is currently hindered by a lack of both prototype models and a comprehensive theoretical foundation. Addressing this gap, this study innovatively introduces the first model of a barocaloric refrigeration system, characterized by efficient hydrostatic pressure transitions and rapid heat and cold extraction. The employed refrigerant, neopentyl glycol, is notable for its low cost and significant barocaloric effect. Through the development of a one-dimensional dynamic numerical model for the system, this study investigates the system's temperature variability and operational efficiency under varying design parameters and operating conditions. Simulations suggest that the system could achieve a maximum COP of 13.1 and a refrigeration capacity of 106.4 W at a temperature span of 10 K. Additionally, the system is capable of reaching a maximum temperature span of 18 K under no-load conditions. This research not only underscores the theoretical viability of barocaloric refrigeration, but also provide crucial theoretical support and guidance for the design and construction of the first-generation barocaloric refrigeration prototype. • A first-generation barocaloric refrigeration prototype was innovatively proposed. • A one-dimensional dynamic model for barocaloric refrigeration is established. • The system achieves a notable COP of 13.1 and refrigeration capacity of 106.4 W. • The system can achieve an impressive maximum temperature span of 18 K. [ABSTRACT FROM AUTHOR]

• Organic nanoparticles (IDQNPs) were synthesized by simple, eco-friendly reprecipitation method. • The fluorescence intensity of bulk IDQ was observed as 604 while nanoflakes showed as 1692.06. • IDQ bulk and IDQNPs were studied for their biological evaluation. • Molecular modeling and dynamic simulation were investigated of IDQ bulk compound. The study aimed to synthesize 7,7-dimethyl-10-aryl,-7,8-dihydro-5H-indeno-[1,2- b ]-quinoline-9,11(6H,10H)‑dione nanoparticles (IDQNPs) and to explore their biological activities i.e. anticancer, antioxidant and antibacterial. For this purpose, we prepared IDQNPs in a single non-solvent i.e. water by simple reprecipitation method. These nanoparticles were highly fluorescent organic nanoparticles (FONPs). The DLS measurements detected that 114 nm size of synthesized IDQNPs. A microphotograph taken using field emission scanning electron microscope (FE-SEM) of air-dried nanoparticle film showed nanoflakes with a feathery shape. Moreover, absorption and emission spectroscopy measurements displayed discrete peak of IDQNPs from their bulk molecule. The highly fluorescent IDQNPs ultimately give higher quantum yield compared to parental IDQ. Fluorescent organic nanoflakes are additionally utilized in vitro for anticancer and antimicrobial activity and antioxidant properties. Cytotoxicity of IDQ and IDQNPs were determined on the basis of measurement of in vitro growth inhibition of breast cancer cell lines in 96 well plates by using 5-fluoro uracil as a standard. The in vitro cytotoxicity of the IDQNPs assayed against MCF-7 cell lines showed higher cytotoxicity with the lower IC 50 value i.e. 3.94 than IDQ parent indicating their efficiency in killing the cancer cells even at low concentrations. Furthermore, antioxidant and antibacterial activities were done by DPPH 96 well method and well plate diffusion method respectively. IDQNPs showed significant antioxidant property against DPPH radical. The IDQ parent compound and IDQNPs suspension at concentration 5 mg, 10 mg, and 100 µL, 200 µL respectively does not show activity against E. coli and Stap. Aureus. The molecular docking and dynamic simulation study were as done for IDQ bulk material. The finding of our study recommend that IDQNPs is a suitable candidate for preclinical cancer and antioxidant studies. This report may open a new avenue in the medical field and life science. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper analyzes the dynamic character of a planar multi-degree-of-freedom industrial machine using an industrial robot as a reference model. A nonlinear dynamics model of a multi-body structure including the end effector, base and the manipulator is established using the Lagrange's principle. The validity was verified by ADAMS simulation with the established dynamic model. Focusing on the low-frequency region, the influence of the robot assembly parameters on the vertical vibration response of the body is discussed. Based on the data summary, some optimization recommendations are made. The results of this paper may contribute to the design of vibration isolation for such robotic arm structures. • Considered the nonlinear multi-body dynamics of an industrial machine. • Established a seven-degree-of-freedom nonlinear dynamics model and verified by ADAMS. • Multiple super-harmonic resonance peaks and complex soft nonlinear phenomena were observed. [ABSTRACT FROM AUTHOR]

• A contact multi-body dynamics model of an RV reducer is presented. • Vibration properties of RV reducer under excitation of faulty NBRs are studied. • The accuracy of the dynamic model has been confirmed by experimental tests. • Defect excitation has a unique periodic effect on the RV reducer's vibration. • The condition monitoring of RV reducer is supported by simulation and test data. The rotate vector (RV) reducer's needle roller bearings (NRBs) are vulnerable to wear and flaws such as fatigue spalling of the raceway material. Studying the vibration mechanism and the excitation laws of NRB failures is essential to enhancing the RV reducer's performance and comprehending its operating state. This paper presents a dynamic model of the RV reducer based on the theory of contact multibody dynamics. It integrates internal and external raceway defects and takes into account the synchronous contact interaction between NRB groups and the crankshaft and cycloidal gears, as well as the time-varying mesh stiffness in the planetary gear transmission and cycloidal pin transmission. The study demonstrates that the rolling of bearings and the meshing of internal transmission components are the primary causes of vibration in a healthy RV reducer through experimental verification and dynamic simulation analysis of the system with and without NRB failures. Both the crankshaft rotation frequency and the cycloidal gear rotation frequency affect the vibration excitation source's characteristic frequency. The vibration amplitude of the RV reducer is influenced by bearing flaws on a periodic basis. The impact of internal raceway defects is greater than that of external raceway faults, resulting in a notable rise in vibration amplitude. [ABSTRACT FROM AUTHOR]

Pumped thermal energy storage (PTES) technology offers numerous advantages as a novel form of physical energy storage. However, there needs to be a more dynamic analysis of PTES systems. This paper proposes a dynamic simulation model of the PTES system using a multi-physics domain modeling method to investigate the dynamic response of key system parameters during the system's start-up and variable operating conditions. Additionally, the impact of equipment parameters on system characteristics was analyzed. Furthermore, a comparative analysis was conducted to assess the variation in system characteristics when considering the different working medium properties. The results show that the system cavity volume should be selected as 5 m3, and the initial pressure of the system during the charge/discharge period should be selected as 2.1 MPa and 3.8 MPa, respectively. The system runs to the design operating conditions during the start-up process in about 1400 s. In the process of variable operation conditions, the power load in the charge/discharge period can be increased or reduced from the rated value by gas filling or venting, and the system characteristics change accordingly. The simulation model and research findings will offer theoretical insights for optimizing the design of the PTES system. • A dynamic simulation physical model of the PTES system was proposed. • The dynamic changes in system characteristics were analyzed. • The TES tank's thermal inertia and heat management of the PTES system were analyzed. • The effects of main equipment parameters on system characteristics were analyzed. • System characteristics were compared when using different gas properties. [ABSTRACT FROM AUTHOR]

Flexible capture has high applicability in the removal of space debris. In this paper, a novel adhesive capture mechanism is proposed, the multibody dynamic modeling method of the capture system is detailed, and an investigation of the adhesive capture process by numerical simulation is presented. First, the passive trigger mechanism of the capture device is described. Second, based on the classical rigid body mechanics and the fully parameterized ANCF beam element, the multibody model of the capture device is detailed. A contact detection algorithm is proposed to take the failure of adhesive connection into account, and its robustness and effectiveness are demonstrated. Finally, investigations of the dynamics during the capture process in two typical capture conditions are described and the impact of some system parameters on the capture effectiveness is discussed. The simulation results provide key parameters for the selection of the adhesive material and show the practical applicability of the capture mechanism. [ABSTRACT FROM AUTHOR]

In this paper, we establish a mathematical model to simulate the dynamic behavior of the high-altitude zero-pressure balloon system during the ground dynamic launching process. The dynamic launching mathematical model includes the solution of the bubble shape and the dynamics model derived by taking the bubble, the membrane bundle, the cable, and the gondola as a whole. The bubble shape is considered as a combination of zero circumferential stress shape at the bottom and fully expanded shape at the top. Under the hypothesis, we use the multiple shooting method and the sequential quadratic programming method together to solve the partially expanded shape in the lower bubble region. Based on bubble shapes, the bubble is modeled as a "spring damping system" and we can establish its dynamic model. The "membrane bundle-cable system" is equivalent to a variable mass rope structure and we solve its dynamic behavior by using the mass particle model. We calculate the swing angle of the gondola by its geometry constraint and force analyses. The Hertz contact model and the Coulomb friction law are used to analyzing the contact between the "membrane bundle-cable system" and the ground or the main boom of the launching vehicle. Based on these dynamic models, we calculate the dynamic launching simulation under three operating conditions of the launching vehicle, which corresponds to three ambient wind speeds. The three operational modes of the launching vehicle are the static operation (2 m/s wind speed), the forward operation to chase the bubble (4 m/s), and the backward operation to increase the gondola releasing angle (0 m/s). We analyze the influence of the wind speed and the launching vehicle action on the force and geometric time history of the dynamic launching system. Furthermore, we discuss the three times typical overload in the dynamic launching system and its influencing factors, which are the opening of the roller, the straightening of the "membrane bundle-cable system" and the releasing of the gondola. The purpose of this paper is to present a set of methods and models for the dynamic launching simulation. It not only calculates the shapes of the bubble and simulates the motion of the quasi rope structure system individually, but also the bubble, the "membrane bundle-cable system" and the gondola are combined to establish a complete set of dynamic models to reflect the main characteristics of the dynamic launching process. [ABSTRACT FROM AUTHOR]

• A framework for dynamic simulation of vehicle-terrain systems is discussed. • We develop and implement a cone index-based (CI) model for dynamics simulation. • CI model does not show oscillations and reaches the steady state smoothly. • We compare the CI model to the existing Wong-Reece models. • Methods qualitatively agree in transient states and maximum tractive effort. Simulation of wheel-ground and vehicle-ground interactions is very important in many applications. Achieving accuracy and efficiency is challenging for both soft and hard terrains. This is not only because of the simulation and numerical challenges, but also due to the questionable nature of the existing terrain models. For example, the most widely used terramechanics model is not a representative constitutive relation for a full range of dynamic conditions and applications, but rather a parametrization of steady state conditions. In general, the selection and development of the proper constitutive model and the parametrization of the ground properties are very challenging. Here, we present a unified framework for general wheel-ground interaction which can be used with different terramechanics models. The framework is based on a complementarity formulation and also uses the concept of kinematic constitutive relations, beside the other known concepts for modelling and parametrizing the soil properties. The framework makes it possible to consider the appropriate modelling of the terrain for a broad range of dynamic behaviours and simulation conditions. We will illustrate the material with several examples for off-road conditions. [ABSTRACT FROM AUTHOR]

• Experimental rig and dynamic model of absorption heat transformers were built. • The model was calibrated and validated with experimental data. • The RT and temperature oscillations were reported when solution conditions change. • The fitted formula between the RT, temperature oscillation, and TS were presented. • Recommendations were given to reduce temperature oscillations and shorten RT. An experimental investigation and dynamic simulation of vertical falling-film LiBr/H 2 O absorption heat transformer systems have been reported in this paper. The established 20 kW experimental equipment was used to test the dynamic performance and verified the mathematical model. The experimental results show that there is a time delay between the input heat and output useful heat, and the time delay of the experimental results is 115 s. The simulated results show that the response time increases with increasing total solution mass and increases with decreasing solution mass flow rate. The temperature flow oscillations decrease with increasing total solution mass and decrease when the solution mass flow rate decreases. The response time of the absorption heat transformer is almost linearly related to the characteristic time of solution storage, which provides guidance for the operation and prediction. By adjusting the total solution mass and solution mass flow rate, theoretically the response time can be reduced to approximately 150 s. The temperature change range of the absorber outlet water can be controlled within 0.5 K by reducing the solution mass flow rate. The total solution mass and mass flow rate should be reduced, which can reduce temperature flow oscillations and shorten the time delay. The response time can be predicted by combining the experimental data and the linear relationship of the response time for any absorption heat transformer. [ABSTRACT FROM AUTHOR]

Autonomous on-orbit servicing, such as capture, refuel, repair and refurbishment of on-orbit satellites using a robotic arm mounted on servicing satellite is one of the important components of future's space missions. Space robots increase reliability, safety, and ease of execution of space operations, but pose a novel challenge due to micro-gravity and space environments. While capturing high speed orbiting objects, robotic arms undergo impact and require appropriate modeling of the system. In this paper, a unified framework is provided for modeling impact dynamics, post-capture stabilization and target maneuvering of a multi-arm robotic system mounted on a servicing satellite while capturing orbiting objects. The dynamic model of multi-arm space robot is obtained using the Decoupled Natural Orthogonal Complement (DeNOC) based formulation and closed-loop constraint equations. All three phases of the capturing operation, namely, approach, impact, and post-impact are modeled using Impulse-momentum approach and conservation of momentum. In the approach phase, robot arms are planned to move from its initial configuration to the desired capture configuration. In the impact phase, a framework is developed to estimate the impulse forces and changes in the generalized velocities caused by the impact. In post-impact phase, these velocities are used as initial conditions for the post-impact dynamics simulations. The uncontrolled dynamics during post-impact will result in an undesirable motion, thus post-impact reactionless control (minimum base disturbance) strategy is used to maneuver the space robot's arms and target object. As such, the robotic arms can be used to maneuver an astronaut for repair of satellite. Most of the times the parameters of target object are not known. Hence, an adaptive reactionless control strategy has been devised for capturing object with unknown parameters. The effectiveness of the framework is shown using a dual-arm robot mounted on a servicing satellite performing capturing operation for multiple objects. The effects of relative velocity and angle of approach on the impact forces are also investigated. • Unified framework for impact modeling and post-impact control of orbiting objects. • Post-impact reactionless control for stabilization of the multi-arm robot is proposed. • Numerical studies of impact for multi-arm open and closed-loop impacts are presented. • An adaptive reactionless control algorithm is proposed to capture unknown targets. • Effect of relative velocity and angle of approach on impact forces is analyzed. [ABSTRACT FROM AUTHOR]

• The combined effect of switch rail structure, longitudinal coupler force and friction coefficient caused the derailment. • Longitudinal coupler force should be considered when investigating the derailment of empty freight trains. • Reducing the longitudinal coupler force and the wheel rail friction coefficient can effectively reduce derailment risk. • Installing a guard rail in front of the switch can effectively prevent freight train derailment in the turnout switch. The derailment of railway vehicles at a turnout is a worldwide concern. However, the derailment of empty freight trains in the switch section of a turnout in the diverging route is rarely concerned. Therefore, in order to analyse the derailment mechanism of empty freight trains in the turnout switch area and to propose appropriate preventive measures, field investigation and dynamic simulation of the derailment are carried out on the basis of an empty freight train derailment in the turnout switch area of the diverging route. Firstly, the background of the derailment is presented and the potential influencing factors of the derailment are analysed according to the field investigation. Secondly, a detailed train-turnout dynamic model is established, taking into account the variable cross-sections of the turnout switch rail and the effect of the longitudinal coupler force. Thirdly, based on the model, the derailment mechanism of the empty freight train is revealed through theoretical analysis and simulation calculation. Finally, the effect of the potential derailment influencing factors is analysed and preventive measures are proposed to reduce the derailment risk of the empty freight train at the turnout switch area in the diverging route. The results indicate that this derailment is caused by the combined effect of the inherent structural characteristics of the switch, the large longitudinal coupler force, and the high wheel rail friction coefficient. The possibility of derailment can be reduced by reducing the longitudinal coupler force and the wheel rail friction coefficient. In addition, the installation of a guard rail in front of the turnout can effectively prevent empty freight train derailment in the turnout area. [ABSTRACT FROM AUTHOR]

The landing airbag system, a mechanism composed of thin-walled structures, is designed to ensure the safe landing of a lander. To investigate the dynamic behavior of the landing airbag with large deformations, a novel modeling approach incorporating gas exchange and frictional contact is proposed. The Absolute Nodal Coordinate Formulation (ANCF) is introduced to model the flexible airbag. Subsequently, the gas parameters inside the airbag are calculated by integrating the Control Volume (CV) Method and the energy conservation equation. Additionally, based on master–slave techniques, a frictional contact formulation for the thin-walled structure and the rigid plane is presented, in which the normal contact force is estimated using the penalty method, and the velocity-based friction model accounting for the stick–slip transition characterizes the tangential friction. Furthermore, the bounding box technology is adopted to improve contact detection efficiency. A series of numerical examples are performed, which demonstrates the proposed model's advantages in terms of precision and versatility. Finally, the landing dynamic characteristics of the airbag landing system for the small lunar lander are successfully revealed, and the parameter analysis for the airbag system is expected to aid the design optimization of the airbag cushioning system. • A model with good convergence and precision for pneumatic membranes is established. • The control volume method with energy conservation is used to describe gas states. • The approach considering the stick–slip transition is used for the friction. • The landing dynamic characteristics of the small lunar lander are revealed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nonlinear dynamic model of a green ammonia synthesis system is developed. • Start-up of H 2 and N 2 subsystems and warm start-up of ammonia reactor are studied. • System dynamic responses under fluctuations of renewable energy are also analyzed. • Bed temperature, H 2 /N 2 ratio and pressure are well maintained by PID controllers. • Buffer tank decreases the reactor variation and is important for pressure control. Green ammonia production system driven by renewable electricity will be under frequent dynamic operation due to the fluctuation of renewable energy. The nonlinear dynamic model of a green ammonia synthesis system is developed and the dynamic responses of PEM (proton exchange membrane) electrolysis subsystem, PSA (Pressure swing adsorption) subsystem and ammonia synthesis subsystem during the start-up process and under the fluctuation of renewable electrical current are analyzed. The start-up dynamic results show that the hydrogen production rate of PEM electrolysis system is positively correlated to the current. The nitrogen output of PSA system is affected by the adsorption time, adsorption pressure, bed length, and air velocity. A start-up period of 300 min from the warmed-up state to the design state can maintain the temperature rise rate of the ammonia synthesis reactor at approximately 40 K/h. The dynamic results under step fluctuations of electrical current show that the PEM electrolysis subsystem and the PSA subsystem response fast compared to the ammonia synthesis reactor and buffer tanks. Using large buffer tanks to smooth the fluctuation allows the system to slide with the variation of renewable current to some extent, resulting in a higher outlet ammonia fraction when the current increases. Different volume ratios of the hydrogen tank to the nitrogen tank volume can lead to different variations of the hydrogen/nitrogen ratio. PID controllers can effectively maintain the bed temperatures, hydrogen/nitrogen ratio, and pressure of the ammonia synthesis reactor at their set points despite fluctuations in renewable electrical current. Buffer tanks are necessary to compensate for the imbalance between the flow rate fluctuation caused by current change and the flow rate regulation caused by PID controllers. [ABSTRACT FROM AUTHOR]

• Experimentally-validated model to predict size and distribution of nanoparticles. • Model couples time-resolved fluid dynamic simulations with population balance. • Increasing mixing rate, increases overall nanoparticle synthesis but not local rate. • Combination of fast mixing and high rate leads to a burst of nuclei formation. Achieving size control during nanomaterial synthesis is critical for their deployment in numerous applications due to their strong size-properties relationships. However, it remains a challenge in the field due to multi-step mechanisms in nanoparticle synthesis. In this paper, we present an experimentally-validated model able to predict the particle size and distribution of silver nanoparticles synthesised in flow reactors by coupling time-resolved fluid dynamic simulations with population balance. The model reveals fundamental correlations between reactor design and the corresponding size of the nanoparticles. It shows that increasing mixing rate, increases the overall rate of nanoparticle formation, where nanoparticle synthesis takes place homogeneously in the whole of the reaction volume. In contrast, when there is a distinguishable interface between reactant streams (i.e. low mixing rate), nucleation and growth take place in a small fraction of the reaction volume in the interface between the inlet streams. The combination of fast mixing and high average nucleation rate can lead to a burst of nuclei formation translated in small size and narrow size distribution. This work presents a new approach for the use of computational-guided design of reactors for the synthesis of nanomaterials to move the field away from current trial-and-error strategies. [ABSTRACT FROM AUTHOR]

Optimizing district heating (DH) systems in a holistic manner is often impeded by the computational complexities associated with network modeling. This study introduces a novel, efficient and theoretically accurate method for dynamic thermal modelling of DH pipes. The approach is to track water frontiers traveling along the pipe using discrete event simulation (DES) paradigm. As the DES method is based on variable time steps, the computational effort is significantly reduced compared to earlier methods. The proposed model can compute outlet water temperature, temperature profile along the pipe, and heat loss based on variable inlet temperature and flow rate. The DES model was validated by comparison with real measurements of a long DH pipe. Four variants of the model with different temperature profile assumptions and interpolation methods were compared. Numerical results show that the DES model can accurately predict outlet water temperature with a maximum discrepancy of 0.52 °C. The mean error of simulated outlet temperature was −0.01 ± 0.02 °C. Average computation time for 24-h simulation was 59 μs. Overall, this study shows that the DES method is appropriate for variable time step simulation for DH pipe, potentially, for network simulation. Our study may also inspire variable time step implementation in other energy applications. • New accurate method for dynamic thermal modelling of district heating pipe. • Lagrangian modelling approach with variable time steps. • Detailed calculation of temperature profile and heat loss. • Fast implementation using the Discrete Event Simulation paradigm. • Model is validated by comparison with real measurement data. [ABSTRACT FROM AUTHOR]

• A novel virtual sensor model combining with measurement and simulation data is proposed. • Uncertainty and nonlinearity of engine are compensated by the feature adaptive fusion. • DDPG is used to adaptively optimize the source domain of feature similarity-based TL. • Dynamic simulation performance of engine model is improved by feature enhancement. • Transition simulation comparison of FSTL-DDPG, FSTL, and DMD-LSTM methods. Sensors are difficult to arrange inside complex aero-engine systems because of harsh operating environment. Aero-engine thermodynamic models can be used as virtual sensors to provide the basis for diagnosis and control. The modeling based on mechanism equations can be well explained, but its over-reliance on component characteristics lead to poor handling of strong dynamic. This paper proposed a novel source-domain-adaptive dynamic modeling framework of Feature Similarity-based Transfer Learning (FSTL) based on Deep Deterministic Policy Gradients (DDPG), which can mitigate for these shortcomings to a certain extent through little measurement data. The field startup signals are used to form the target domain, and the reward function is constructed by utilizing the domain similarity of feature fusion through FSTL. A dynamic model of a gas engine with a rated speed of 9000 rpm is carried out using the proposed learn-to-learn framework. The verification results of the startup process indicate that FSTL-DDPG has the most outstanding performance of 0.9536 regression coefficient and 0.46 % mean square error, which are improved by about 16.9 % and 62.0 % compared with FSTL and Dynamic Mode Decomposition combined with Long Short-Term Memory (DMD-LSTM). Qualitative and quantitative analysis revealed that FSTL-DDPG has better simulation performance and matching degree of physical laws. [ABSTRACT FROM AUTHOR]

The rotary desiccant wheels application in the air conditioning systems are used for the air dehumidification by means of hygroscopic layers for water vapor adsorption. Nevertheless, external heat sources are required for water desorption to close the air treatment cycle. This paper investigates on the possibility to integrate in that cycle a new component, such as the trans -critical CO 2 heat pump, to reduce the contribution of external thermal sources. In so doing, the high temperature waste heat discharged by the heat pump hot sink can be fruitfully exploited. Additionally, a PV array has been added to the typical layout based on the solar collectors, in order to assure the heat pump electrical driving. The energy analysis is carried out by calculating the energy performance indicators of the whole cooling system, simulating it by a dynamic model built in the MATLAB SIMULINK environment. Specifically, an air handling unit has been properly sized to supply cooling load to a reference conference hall of 1200 m3, with changes in boundary conditions (i.e. solar radiation, daily temperature and relative humidity variations). Indeed, three different cities representing the most typical Italian climatic zones, have been considered for assessing the proposed technical option suitability. • A quick overview on the Trans -critical CO2 heat pumps features has been presented. • Dynamic simulation model of a hybrid solar cooling systems with CO2 HP has been built. • Fundamental equations of each component have been reported and implemented in Matlab. • Hybrid system energy performance has been evaluated in three different Italian cities. • Other key performance indicators have been presented and discussed. [ABSTRACT FROM AUTHOR]

During the past few years a significant effort has been performed in order to promote the use of renewable energy sources. However, one of the main barriers for a mature commercialization is due to the unpredictability of the renewable power production, mainly in case of wind and solar energy. Unfortunately, electric storage devices are often poorly profitable. Therefore, some more stable renewable energy systems must be designed. In this framework, this paper presents a novel hybrid renewable system consisting of Building Integrated PhotoVoltaic panels and small-scale Wind Turbines and double-stage heat pumps. This combination is very promising since it reduces the typical fluctuations of solar or wind systems, achieving a more stable profile of the overall power production. A detailed dynamic simulation model is developed in TRNSYS environment, including validated models for all the components and a suitable thermoeconomic analysis. A case study is implemented for a hotel building, where the space heating and cooling energy is supplied by an electrically driven reversible air-to-water Heat Pump, supplied by the electricity produced by Building Integrated PhotoVoltaic panels and Wind Turbines. the thermal energy recovered from the HP desuperheater is coupled with the thermal energy produced by a two-stage cascade cycle Heat Pump to produce domestic hot water. Results are presented in terms of hourly, monthly and yearly system performance data as well as by discussing the results of a detailed sensitivity analysis performed to detect the optimum configuration and weather zone of this hybrid renewable system. An analysis of the building envelope features is also performed, according to the nearly zero energy buildings target. Results showed that the combination of photovoltaic and wind technologies allows one to significantly enhance the stability of the renewable power production. Results also show that the use of heat pumps leads to a reduction of the primary energy demand for building space heating/cooling and domestic hot water by 30%. A payback period of about 5.2 years is obtained and the optimum configuration suggests adopting one 20 kW Wind Turbine for the selected case study. • Building integrated photovoltaic panels coupled with small size wind turbines. • Dynamic simulation model developed with TRNSYS software. • Sensitivity analysis on the building envelope features and weather zones. • Simple payback period of about 4.4 years for two 20 kW wind turbines. [ABSTRACT FROM AUTHOR]

In comparison with other types of conventional positive displacement compressors for domestic refrigerators, oil-free linear compressors have a number of advantages due to their compactness, low friction, limited number of moving parts, and excellent performance. Limited work was found in the open literature related to comprehensive compressor modeling and model validation of commercially available linear compressors. A comprehensive and generalized simulation model of linear compressors has been recently presented by the same authors. The current paper expands on this work by using experimental data for the simulated compressors to characterize their performance over the operating envelopes and to validate the linear compressor model. The validated model was then used to quantify the major sources of losses and analyze system vibration as well as piston eccentricity, which ultimately could be used to design the next generation of linear compressors. [ABSTRACT FROM AUTHOR]

A variable speed photovoltaic direct-current (DC) refrigerator (VSPVDR) system is proposed in this paper. In the VSPVDR system, the photovoltaic (PV) cells are directly connected to the compressor without batteries and inverter, and the DC compressor speed changes with the radiation intensity. In the paper, a dynamic model is presented to simulate the behavior of the VSPVDR, and several prototype experiments are conducted to validate the model. On this basis, the impacts of the compressor speed control strategy, ambient temperature and the radiation intensity have been studied. Compared with the fixed speed mode, the cooling capacity of the variable speed mode increases by 32.76% and the average PV utilization efficiency increases by 45.69%. When ambient temperature increases, the average cooling capacity decreases significantly, but the increase of average power consumption is not obvious, which reveals that the ambient temperature has greater influence on the cooling capacity and has less influence on the power consumption. The radiation intensity has a significant impact on system performance. When the radiation intensity increases, the cooling capacity increases significantly. • A VSPVDR system without batteries and inverter is introduced. • A dynamic model of the system validated by prototype experiments is presented. • The average PV utilization efficiency of variable speed model increases by 45.69%. • The impacts of ambient temperature and radiation intensity have been discussed. [ABSTRACT FROM AUTHOR]

Objectives: The objective of this article is to describe the unique challenges and present potential solutions and approaches for economic evaluations of precision medicine (PM) interventions using simulation modeling methods.Methods: Given the large and growing number of PM interventions and applications, methods are needed for economic evaluation of PM that can handle the complexity of cascading decisions and patient-specific heterogeneity reflected in the myriad testing and treatment pathways. Traditional approaches (eg, Markov models) have limitations, and other modeling techniques may be required to overcome these challenges. Dynamic simulation models, such as discrete event simulation and agent-based models, are used to design and develop mathematical representations of complex systems and intervention scenarios to evaluate the consequence of interventions over time from a systems perspective.Results: Some of the methodological challenges of modeling PM can be addressed using dynamic simulation models. For example, issues regarding companion diagnostics, combining and sequencing of tests, and diagnostic performance of tests can be addressed by capturing patient-specific pathways in the context of care delivery. Issues regarding patient heterogeneity can be addressed by using patient-level simulation models.Conclusion: The economic evaluation of PM interventions poses unique methodological challenges that might require new solutions. Simulation models are well suited for economic evaluation in PM because they enable patient-level analyses and can capture the dynamics of interventions in complex systems specific to the context of healthcare service delivery. [ABSTRACT FROM AUTHOR]

This research describes the influence of nano-sized aluminum with varying contents (0–20 wt%) on the combustion behaviors of HMX/GAP/Al in aspects such as burning rate, surface temperature, gas phase temperature, mole fraction of species, and specific impulse. A rigorous mathematical model is developed for three phases (solid phase, condensed phase, and gas phase) with detailed kinetics. This model consists of 507 gas phase reactions and 4 condensed phase reactions of HMX/GAP/Al combustion. The model also emphasizes the phase transitions and reactions of aluminum in the gas phase. Based on this model, dynamic simulation is carried out at various propellant compositions and operating pressures by means of the moving boundary approach using gPROMS software package. The simulation results are in close agreement with the experimental data at slight marginal errors for HMX/Al combustion, predicting the combustion behaviors for the HMX/GAP/Al system. Accordingly, the model predicts the gas phase temperature of 3061 K for the 20 wt% Al and the specific impulse of 258.53 s for the 15 wt% Al of HMX/GAP/Al propellant under an operating pressure of 100 atm. The increase in burning rate and specific impulse by increasing the pressure is also indicated. According to this study, the addition of aluminum particles with a content range of 15–20 wt% considerably improves combustion behaviors. By dynamic modeling and simulation, a detailed framework for studying the multi-phase combustion of aluminized solid propellant is introduced. [ABSTRACT FROM AUTHOR]

• A Bond Graph model and a simulation of a parabolic-trough collector are proposed. • A good agreement is observed between the simulated results and experimental tests. • Exergy dynamic performance assessment of the PTC is presented. • The PBG model proposed is recommended for a PTC solar field control. The present paper deals with the modeling of a solar parabolic trough collector (PTC).The system is described by a lumped parameter model; its dynamic modeling is performed using the bond graph methodology which allows having a graphical structure of the modeled phenomena where the multi-domain coupling relationships are explicitly represented. The thermal domain of the pseudo bond graph (PBG) supports all heat transfer modes established between the environment, the glass cover, the absorber tube and the fluid. The mass accumulation in the control volume is not taken into account since its dynamic effect remains largely negligible as demonstrated in this contribution. The state equation of the system is developed from the laws of the junctions, the resistance elements and capacitance elements. Numerical simulation is carried out via the Matlab software environment and the predicted results are compared with the experimental tests of the Sandia National Laboratory. For on-sun tests, the average relative errors obtained are about 0.17% for the heat transfer fluid (HTF) output temperature and about 0.96% for the energy efficiency. In the case of off-sun tests, the average relative error calculated for the predicted HTF output temperature is estimated at 0.08% and the heat losses absolute error is equal to 4.9 (W/m2). According to the previous comparisons, there is reason to affirm that the proposed model can accurately predict the thermal behavior of the collector. Finally, this work includes a case study that consists of PTC exergy performance assessment under climate conditions of three different North Africa sites. [ABSTRACT FROM AUTHOR]

• Propose a new kind of deformable terrain-adaptive robot, and validate its adaptability in simulation and experiment. • Analyze the kinemics characters and construct the dynamic modeling of the prototype which can capture the sliding tendency and the shake of vertexes when contacting. • Design different gaits for several typical terrains using the dynamic model, and validate the gaits via prototype experiments. This paper proposes a deformable polygonal robot, aiming at high flexibility for crawling on rough terrain. A planar prototype is first developed to perform laboratory tests on a two-dimensional track. The shape of this prototype is continuously changed by the driving servos, and this determines the locomotion of the robot over a given terrain. A dynamic model considering the contact forces is applied to evaluate the performance of different gaits via simulation. Locomotion gaits are designed by kinematics, and validated first through dynamic simulation, and then by experiments. Based on the prototype, we carried out a series of laboratory experiments on several typical terrains, including slopes, obstacles, and steps. Results from simulations and experiments show that the robot is highly capable of adapting to complex terrains. [ABSTRACT FROM AUTHOR]

• Dynamic simulation of batch and perfusion fermentation of Chinese hamster ovary cells. • Kinetic models describe cell growth, substrate consumption and generation of products. • Sensitivity analysis performed establishes design and operating parameters for perturbation. • Economic analysis and production time evaluation is heavily dependent on media and cell usage. • Modelling problem open to dynamic optimization given detailed industrial and economic data. Chinese Hamster Ovary (CHO) cells are widely used in fermentation towards biopharmaceutical manufacturing. The present paper presents dynamic mathematical models of two different CHO culture modes: one batch mode for the production of interferon (IFN)- γ , and one perfusion mode for the production of a monoclonal antibody (mAb). The dynamic models have been used for simulating cell, substrate, by-product and product concentration trajectories, which have been compared against previously published experimental results. A sensitivity analysis of both models has been conducted, in order to analyse the relative importance of different operating parameters towards biopharmaceutical process design. An economic analysis has also been subsequently performed: production time and net present cost for given target capacities have been evaluated, using the validated dynamic models for the batch and perfusion modes. Economic trends are discussed for variable initial concentration of viable CHO cells to be used in bioreactors: the latter has been recognised as the most sensitive model parameter for both culture modes. [ABSTRACT FROM AUTHOR]

Among the various heating technologies that can be applied to urban areas district heating is recognized to allow significant reduction in primary energy consumption, provided that the system is properly designed and operated. Thermo-fluid dynamic simulation tools can be of extreme importance in order to achieve this objective. This paper aims at presenting a thermo fluid dynamic model for the detailed simulation of large district heating network and showing how it can be usefully applied to examine options for the reduction of primary energy consumption. The model is tested using experimental data and then applied for analyzing transient operations of the Turin district heating network, which is the largest network in Italy and one of the largest in Europe. A comparison between simulations and experimental results shows that the model is able to predict the temperature in the nodes of the network with good accuracy. The thermal power required to each plant is also calculated with a good level of accuracy. The model can be used for the simulation of operational strategies, thus representing a versatile and important tool for the implementation of advanced management such as the installation of local storage units or the variation of user request schedules. • A thermo-fluid dynamic model for the detailed simulation of large DHNs is proposed. • The model receives data from the substations as the input. • The transient simulation of the Turin DHN is compared with measurements. • The model can be applied to implement advanced management strategies. [ABSTRACT FROM AUTHOR]

A novel dynamic model is proposed for a space shaft, which is used to analyze the dynamical processes of the cage during movement. The results achieved from variance analysis reveal that the ranges between guide and pocket clearances jointly influence the abnormal wear of the cage. From dynamic simulations and theoretic prediction, optimal ranges of guide distance and pocket clearance very from 365 to 375 µm, and 445 and 460 µm, respectively. The experimental results are in good agreement with those of theoretical and simulated outcomes, making abnormal wear of the cage reduce from 41.3% to 10%. These findings provide new insights to design and manufacture a high-performance space shaft cage to avoid abnormal wear worked at low temperature environment. [ABSTRACT FROM AUTHOR]