Comprehensive Dynamic Model Research Articles

System Level Modeling of Timing Margin Loss Due to Dynamic Supply Noise for High-Speed Clock Forwarding Interface

Supply noise is conventionally modeled as a fixed voltage noise specification. Modern integrated circuit design cannot meet a conventional fixed voltage noise specification due to large dynamic noise. These days, applications of multicore system-on-chip (SoC) and multichip system-in-package become very common. The impact of dynamic noise can be even more detrimental for multicore or SoC design as supply noise can be completely uncorrelated between two regions whose powers are different. Accurate modeling of noise impact requires a new approach that can account for any jitter tracking in clock forwarding systems. In this paper, a comprehensive dynamic noise modeling methodology is presented to analyze jitter impact in various clock forwarding interfaces for multicore and SoC designs. The proposed method uses the frequency-dependent jitter sensitivity function with a noise spectrum to model the desired jitter tracking.

New Method of Rigorous Modeling and CFD Simulation for Methanol—Steam Reforming in Packed-Bed Reactors

A comprehensive dynamic mathematical model was developed to analyze methanol−steam reforming in catalytic packed-bed reactor. The contributions of all molecular and convective terms of momentum, heat, and mass transfer were taken into consideration, with the inclusion of effectiveness factor. Effects of two predominant parameters: particle size and the wall heat flux on the reactor performance for the methanol−steam reforming were examined. It was revealed that by increasing the average particle size from 700 to 3200 µm, which corresponded to porosity values of 0.4 and 0.6, the effectiveness factor decreased by nearly 80% and subsequently the overall methanol conversion decreased by around 74%. Besides, through a set of organized simulation runs, it was discovered that with increasing the dimensionless wall heat flux from 0 to 0.2 Wm−1 K−1, the methanol conversion was enhanced by 87%.

From Passive Dynamic Walking to Passive Turning of Biped walker

Dynamically stable biped robots mimicking human locomotion have received significant attention over the last few decades. Formerly, the existence of stable periodic gaits for straight walking of passive biped walkers was well known and investigated as the notion of passive dynamic walking. This study is aimed to elaborate this notion in the case of three dimensional (3D) walking and extend it for other maneuvers, specifically curved walking or turning. For this purpose, the motion of a general 3D compass gait model on a ramp has been analyzed theoretically in detail. A comprehensive dynamic modeling with respect to the vertical fixed frame is used based on Lagrangian and augmented methods. In addition to 3D passive straight walking, the results confirm the existence of some passive turning motions for the biped walker towards the steepest decent of the ramp. It was shown that the value of passive turning is strictly concerned to the value of initial perturbed condition of the walker, especially to the value of heading angle. A parameter analysis was also accompanied to examine the change in the characteristics of such passive motions caused by the change in model parameters.

Multi-objective process optimisation of beer fermentation via dynamic simulation

Fermentation is an essential step in beer brewing: when yeast is added to hopped wort, sugars released from the grain during germination are fermented into ethanol and higher alcohols. To study, simulate and optimise the beer fermentation process, accurate models of the chemical system are required for dynamic simulation of key component concentrations. Since the entire beer production process is a highly complex series of chemical reactions with the presence of over 600 species, many of the specific interactions are not quantitatively understood, a comprehensive dynamic model is impractical.This paper presents a computational implementation of a detailed model describing an industrial beer fermentation process, which is used to simulate published temperature manipulations and compare results with those obtained following the protocol currently in place at WEST Beer brewery (Glasgow, Scotland, UK). A trade-off between design objectives has been identified, making determination of a single optimal scenario challenging. A simulated annealing (SA) algorithm has been developed in order to pursue stochastic optimisation of the fermentor temperature manipulation profile, on the basis of generating an enormous set of plausible manipulations which adhere to suitable operability constraints at an appropriate level of temporal domain discretisation. The objective function considers ethanol maximisation as well as batch time minimisation (with variable weight allocation), and explicit constraints on diacetyl and ethyl acetate concentrations. Promising temperature manipulations have been determined, allowing for batch time reductions of as high as 15h: this represents a substantial decrease in production cycle time, and is thus expected to improve annual plant throughput and profitability, without any discernible effect on flavour.

Inactivation of Escherichia coli, Bacteriophage MS2, and Bacillus Spores under UV/H2O2 and UV/Peroxydisulfate Advanced Disinfection Conditions.

Ultraviolet light (UV) combined with peroxy chemicals, such as H2O2 and peroxydisulfate (PDS), have been considered potentially highly effective disinfection processes. This study investigated the inactivation of Escherichia coli, bacteriophage MS2, and Bacillus subtilis spores as surrogates for pathogens under UV/H2O2 and UV/PDS conditions, with the aim to provide further understanding of UV-based advanced disinfection processes (ADPs). Results showed that one additional log of inactivation of E. coli was achieved with 0.3 mM H2O2 or PDS at 5.2 × 10(-5) Einstein·L(-1) photo fluence (at 254 nm) compared with UV irradiation alone. Addition of H2O2 and PDS greatly enhanced the inactivation rate of MS2 by around 15 folds and 3 folds, respectively, whereas the inactivation of B. subtilis spores was slightly enhanced. Reactive species responsible for the inactivation were identified to be •OH, SO4(·-), and CO3(·-) based on manipulation of solution conditions. The CT value of each reactive species was calculated with respect to each microbial surrogate, which showed that the disinfection efficacy ranked as •OH > SO4(·-) > CO3(·-) ≫ O2(·-)/HO2(·). A comprehensive dynamic model was developed and successfully predicted the inactivation of the microbial surrogates in surface water and wastewater matrices. The concepts of UV-efficiency and EE/O were employed to provide a cost-effective evaluation for UV-based ADPs. Overall, the present study suggests that it will be beneficial to upgrade UV disinfection to UV/H2O2 ADP for the inactivation of viral pathogens.

Adaptive Critic Design Based Control of Tunnel Ventilation System with Variable Jet Speed

In this paper, an adaptive critic design (ACD) based control algorithm is proposed for road tunnel ventilation systems with jet fans. Firstly, a comprehensive dynamic model is established for control purpose, which considers both the static and dynamic nonlinearities between the pollutant concentration and the jet speed or the air flow inside the tunnel. Vehicle speed and density are also integrated into the model as system external disturbances. To cope with the time-varying model parameters and unknown system uncertainties, one artificial neural network (NN) unit is employed in controlling the jet fans to regulate the pollutant concentration to a desired level, even in the presence of varying working conditions. An additional NN is utilized to approximate the cost-to-go function required for the performance optimization. The proposed scheme is also verified and compared with traditional control design in simulation environment. The simulation results substantiate the conclusion that the adaptive controller can achieve a better regulation performance along with less energy consumption.

Backstepping control with speed estimation of PMSM based on MRAS

This paper presents a backstepping control method with speed estimation of permanent magnet synchronous motor (PMSM) based on model reference adaptive system (MRAS). First, a comprehensive dynamical model of PMSM in d–q axis and its space state equations are established. Next, using Lyapunov stability theorem, based on the backstepping control theory, the PMSM rotor speed and current backstepping controllers are designed. Furthermore, using Popov stability theory, based on MRAS, the PMSM rotor speed observer is designed. Finally, Matlab/Simulink simulation results show that the backstepping control and speed observer are effective and feasible.

KIC 9246715: THE DOUBLE RED GIANT ECLIPSING BINARY WITH ODD OSCILLATIONS

ABSTRACT We combine Kepler photometry with ground-based spectra to present a comprehensive dynamical model of the double red giant eclipsing binary KIC 9246715. While the two stars are very similar in mass ( M 1 = 2.171 − 0.008 + 0.006 M ⊙ ?> , M 2 = 2.149 − 0.008 + 0.006 M ⊙ ?> ) and radius ( R 1 = 8.37 − 0.07 + 0.03 R ⊙ ?> , R 2 = 8.30 − 0.03 + 0.04 R ⊙ ?> ), an asteroseismic analysis finds one main set of solar-like oscillations with unusually low-amplitude, wide modes. A second set of oscillations from the other star may exist, but this marginal detection is extremely faint. Because the two stars are nearly twins, KIC 9246715 is a difficult target for a precise test of the asteroseismic scaling relations, which yield M = 2.17 ± 0.14 M ⊙ and R = 8.26 ± 0.18 R ⊙. Both stars are consistent with the inferred asteroseismic properties, but we suspect the main oscillator is Star 2 because it is less active than Star 1. We find evidence for stellar activity and modest tidal forces acting over the 171 day eccentric orbit, which are likely responsible for the essential lack of solar-like oscillations in one star and weak oscillations in the other. Mixed modes indicate the main oscillating star is on the secondary red clump (a core-He-burning star), and stellar evolution modeling supports this with a coeval history for a pair of red clump stars. This system is a useful case study and paves the way for a detailed analysis of more red giants in eclipsing binaries, an important benchmark for asteroseismology.

Dynamic Characteristics of Positive Pulsed Dielectric Barrier Discharge for Ozone Generation in Air**supported by National Natural Science Foundation of China (Nos. 51366012 and 11105067), Jiangxi Province Young Scientists (Jinggang Star) Cultivation Plan of China (No. 20133BCB23008), Natural Science Foundation of Jiangxi, China (No. 20151BAB206047) and Jiangxi Province Higher School Science and Technology Landing Plan of China (No. KJLD-14015)

A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge (DBD) using parallel-plate reactor in air. The electron energy conservation equation is coupled to the electron continuity equation, the heavy species continuity equation, and Poisson's equation for a better description. The reliability of the model is experimentally confirmed. The model can be used to predict the temporal and spatial evolution of species, as well as streamer propagation. The simulation results show that electron density increases nearly exponentially in the direction to the anode at the electron avalanche. Streamer propagation velocity is about 5.26 × 104 m/s from anode to cathode in the simulated condition. The primary positive ion, negative ion, and excited species are O2+, O3− and O2(1Δg) in pulsed DBD in air, respectively. N2O has the largest density among nitrogen oxides. e and N2+ densities in the streamer head increase gradually to maximum values with the development of the streamer. Meanwhile, the O2+, O, O3, N2(A3Σ) and N2O densities reach maximum values in the vicinity of the anode.

Dynamic simulation of water resource management focused on water allocation and water reclamation in Chinese mining cities

Mining cities have undergone the process of extensive exploitation, which always results in a series of water issues. Integrated water resource management is necessary in improving water supply, allocation and quality without damaging economic development. This article constructs a linear optimization model including a ‘Top-Down’ socio-economic mode, and ‘Bottom-Up’ water quality control and water supply–demand modes with integrated water resource management focused on water allocation and water reclamation. Based on computer simulation, the model can propose a water resource management under the constraints of water supply–demand and water quality control, and the model can precisely predict the influences of water resource management on economic development, water utilization and water quality. Taking Ordos, a Chinese national resource city, as a case study, this model addresses a detailed water resource management, including a water allocation plan among industries and water reclamation plan with technologies, selection, arrangement and subsidies. The implementation of water resource management can fulfill multiple objectives on water quantity, water quality and sustainable economic development. This study indicates that water resource management with a comprehensive dynamic model can be a maneuverable approach to realize the sustainable development of economic growth and water resource utilization, as well as formulate the regional development plan.

New insights into the complex regulation of the glycolytic pathway in Lactococcus lactis. I. Construction and diagnosis of a comprehensive dynamic model

This article and the companion paper use computational systems modeling to decipher the complex coordination of regulatory signals controlling the glycolytic pathway in the dairy bacterium Lactococcus lactis. In this first article, the development of a comprehensive kinetic dynamic model is described. The model is based on in vivo NMR data that consist of concentration trends in key glycolytic metabolites and cofactors. The model structure and parameter values are identified with a customized optimization strategy that uses as its core the method of dynamic flux estimation. For the first time, a dynamic model with a single parameter set fits all available glycolytic time course data under anaerobic operation. The model captures observations that had not been addressed so far and suggests the existence of regulatory effects that had been observed in other species, but not in L. lactis. The companion paper uses this model to analyze details of the dynamic control of glycolysis under aerobic and anaerobic conditions.

Diet-Dependent Modular Dynamic Interactions of the Equine Cecal Microbiota.

Knowledge on dynamic interactions in microbiota is pivotal for understanding the role of bacteria in the gut. We herein present comprehensive dynamic models of the horse cecal microbiota, which include short-chained fatty acids, carbohydrate metabolic networks, and taxonomy. Dynamic models were derived from time-series data in a crossover experiment in which four cecum-cannulated horses were fed a starch-rich diet of hay supplemented with barley (starch intake 2 g kg−1 body weight per day) and a fiber-rich diet of only hay. Cecal contents were sampled via the cannula each h for 24 h for both diets. We observed marked differences in the microbial dynamic interaction patterns for Fibrobacter succinogenes, Lachnospiraceae, Streptococcus, Treponema, Anaerostipes, and Anaerovibrio between the two diet groups. Fluctuations and microbiota interactions were the most pronounced for the starch rich diet, with Streptococcus spp. and Anaerovibrio spp. showing the largest fluctuations. Shotgun metagenome sequencing revealed that diet differences may be explained by modular switches in metabolic cross-feeding between microbial consortia in which fermentation is linked to sugar alcohols and amino sugars for the starch-rich diet and monosaccharides for the fiber-rich diet. In conclusion, diet may not only affect the composition of the cecal microbiota, but also dynamic interactions and metabolic cross-feeding.

Aggressive Turn-Around Manoeuvres with an Agile Fixed-Wing UAV

This paper investigates an aerobatic manoeuvre performed by an agile fixed-wing unmanned aerial vehicle, with the intent of determining how best the manoeuvre can be automated. The manoeuvre is an aggressive turn-around: a 180 degree reversal of the aircraft’s heading, in which the space required for completing the turn is minimized. A comprehensive dynamics model of an agile fixed-wing aircraft is used to design trajectories of the manoeuvre off-line using optimal control. A methodology for evaluating the suitability of controllers for executing the manoeuvre is also presented.

Ocean dynamic processes causing spatially heterogeneous distribution of sedimentary caesium-137 massively released from the Fukushima Daiichi Nuclear Power Plant

Abstract. Massive amounts of anthropogenic radiocaesium 137Cs that were released into the environment by the Fukushima Daiichi Nuclear Power Plant accident in March 2011 are widely known to have extensively migrated to Pacific Ocean sediment off of eastern Japan. Several recent reports have stated that the sedimentary 137Cs is now stable with a remarkably heterogeneous distribution. The present study elucidates ocean dynamic processes causing this heterogeneous sedimentary 137Cs distribution in and around the shelf off Fukushima and adjacent prefectures. We performed a numerical simulation of oceanic 137Cs behaviour for about 10 months after the accident, using a comprehensive dynamic model involving advection–diffusion transport in seawater, adsorption and desorption to and from particulate matter, sedimentation and suspension on and from the bottom, and vertical diffusion transport in the sediment. A notable simulated result was that the sedimentary 137Cs significantly accumulated in a swath just offshore of the shelf break (along the 50–100 m isobath) as in recent observations, although the seabed in the entire simulation domain was assumed to have ideal properties such as identical bulk density, uniform porosity, and aggregation of particles with a single grain diameter. This result indicated that the heterogeneous sedimentary 137Cs distribution was not necessarily a result of the spatial distribution of 137Cs sediment adsorptivity. The present simulation suggests that the shape of the swath is mainly associated with spatiotemporal variation between bottom shear stress in the shallow shelf (< 50 m depths) and that offshore of the shelf break. In a large part of the shallow shelf, the simulation indicated that strong bottom friction suspending particulate matter from the seabed frequently occurred via a periodic spring tide about every 2 weeks and via occasional strong wind. The sedimentary 137Cs thereby could hardly stay on the surface of the seabed with the result that the simulated sediment-surface 137Cs activity tended to decrease steadily for a long term after the initial 137Cs migration. By contrast, in the offshore region, neither the spring tide nor the strong wind caused bottom disturbance. Hence, the particulate matter incorporated with 137Cs, which was horizontally transported from the adjacent shallow shelf, readily settled and remained on the surface of the sediment just offshore of the shelf break.

Three-Dimensional Blade Stacking Strategies and Understanding of Flow Physics in Low-Pressure Steam Turbines—Part II: Stacking Equivalence and Differentiators

Optimization of blade stacking in low-pressure (LP) steam turbine development constitutes one of the most delicate and time-consuming parts of the design process. This is the second part of two papers focusing on stacking strategies applied to the last stage guide vane and represents an attempt to discern the aerodynamic targets that can be achieved by each of the well-known and most often used basic stacking schemes. The effects of lean and twist have been investigated through an iterative process, involving comprehensive 3D computational fluid dynamics (CFD) modeling of the last two stages of a standard LP, where the basic lean and twist stacking schemes were applied on the last stage guide vanes while keeping the throat area (TA) unchanged. It has been found that it is possible to achieve the same target value and pattern of stage reaction by applying either tangential lean or an equivalent value of twist. Moreover, the significance of axial sweep on hub reaction has been found to become pronounced when the blade sweep is carried out at constant TA. The importance of hub-profiling has also been demonstrated and assessed. Detailed analysis of the flow fields has provided an overall picture, revealing the differences in the main flow parameters as produced by each of the alternative basic stacking schemes.

Simulating the Dynamics of E-waste Production from Mobile Phone: Model Development and Case Study of Rwanda

Mobile phone sales and stocks showed an exponential growth in the past years globally and the annual number of mobile phones produced surpassed one billion in 2007. This soaring growth of related e-waste deserves sufficient attentions paid to it regionally and globally, since 40% of its total weight is made from metallic, of which 12 elements are identified to be highly hazardous. Different methods from different part of the world have been used to estimate the obsolete mobile phones but none has developed a dynamic model and handled the discrepancy resulting from improper approach and error in the input data. This study aimed to develop a comprehensive dynamic system model for simulating the dynamism of e-waste production from mobile phone specifically for African developing countries and to prevail over the previous errors. The logistic model method combined with Stella program were used to carry out this study. Then the simulation for Rwanda was conducted and compared with others countries’ results as model testing and validation. The results showed that Rwanda produced about 1.5 million obsolete mobile phones with 125 tons of waste in 2014 and e-waste production peak would appear in 2017. It is expected to reach 4.2 million obsoletes with 352 tons by 2020 along with environmental impact intensity of 21 times of 2005. Moreover, e-waste management policy for developing countries specifically for Rwanda has been suggested to reduce environmental impact up to 40% in 2020 and to 73% in 2030. The present study figured out the dynamism characteristic and outflow of the system design. It is concluded through the model testing and validation that the present dynamic model is competent and could deal with mobile phone e-waste production.

Plantwide control and operating strategy for air separation unit in oxy-combustion power plants

To ensure that air separation unit can bear high ramp rate and flexible operations when integrated into oxy-combustion power plant, this paper focuses on the investigations of plantwide control design and operating strategy for double-column air separation unit without or with liquid oxygen storage drum through dynamic simulation. It is found that three air separation unit types (normal, oversize, and downsize) with the proposed control structure configured with logic control loops (strategies 1, 2, and 3) can achieve 5%/min of high ramp rate and flexible operations such as peak and off-peak or/and energy storage. Compared between the latter two logical controls, strategy 2 would be better because its oxygen product qualities can be maintained closer to their targets. Three integrated patterns between air separation unit and oxy-combustion boiler are proposed to improve operating flexibility, among which oversize case would be more suitable for oxy-combustion power plant since its energy saving (20.33MW) is larger and operating strategy is more flexible than those in downsize (10.76MW) and normal cases. Process control for flexible operations would be an opportunity for engineering, and comprehensive dynamic model with specified control system provides possibility to integrate air separation unit with full-train oxy-combustion power plants.

A comprehensive dynamic model to investigate the stability problems of the rotor–bearing system due to multiple excitations

In this paper, a comprehensive dynamic model is proposed to analyze the dynamic behaviors of the rotor–bearing system. Three types of excitation including the bearing waviness, the unbalanced force and the finite number of balls (varying compliance effect) are considered. Based on the extended Jones–Harris model with five degrees of freedom, the load distribution and then the stiffness of the angular contact ball bearing are obtained theoretically. After introducing the three types of excitation into the model, the bearing stiffness matrix becomes time-varying and many parametric frequencies are found due to the multiple excitations. Then, the stability problems of the parametrically excited rotor–bearing system are investigated utilizing the discrete state transition matrix method (DSTM). The simple instability regions arising from the translational and the angular motions are analyzed respectively. The effects of the amplitude and the initial phase angle of the bearing waviness, the rotor eccentricity, the bearing preload and the damping of the rotating system on the instability regions are discussed thoroughly. It is shown that the waviness amplitudes have significant influences on the instability regions, while the initial phase angles of the waviness almost have no effect on the instability regions. The rotor eccentricity just affects the widths of the instability regions. The increasing of the bearing preload only shifts the positions of the instability regions. Damping could reduce the instability regions but it could not diminish the regions completely.

A Hybrid Meta-heuristic for the Dynamic Layout Problem with Transportation System Design

This paper primarily presents a comprehensive dynamic layout design model which integrates layout and transportation system design via considering more realistic assumptions, such as taking account of fixed-position departments and distance between departments that endanger each other. In addition, specific criteria such as capacity, cost and reliability of facilities are considered in transportation system design decision. The combinatorial nature of the problem necessitates using a meta-heuristic approach to deal with this issue. Therefore, an efficient hybrid meta-heuristic based on variable neighborhood search (VNS) and simulated annealing (SA) is proposed to design a proper dynamic layout for a specific planning horizon. The validity of the superiority of the proposed solution method is proven through comparing with all of the other solution methods upon the original model available in the literature. Finally, an extensive computational results lead to the conclusion that the proposed method outperforms other existing methods. In addition, solving an example from the dynamic layout design of a home appliance manufacturer demonstrates the efficiency of the proposed model and solution algorithm in terms of solution quality to solve real-world instances.

Solar repowering of PCC-retrofitted power plants; solar thermal plant dynamic modelling and control strategies

Solar repowering of high pressure side feed water preheaters of post combustion carbon capture (PCC) retrofitted power plants offers a promising capability to offset the power plant output penalty due to capture plant reboiler duty. In this work, a model based approach is used to investigate the technical, operational and control aspects of the solar thermal installation of the super structure (power plant+PCC+solar thermal plant). The base case is a 660MWe PCC-retrofitted power plant operating at 100% capacity and 90% capture rate in Australia. This is repowered by a solar thermal plant consisting of (a) a parabolic trough solar collector field with 806,520m2 aperture area, (b) a thermal storage system with 8 full load hours of thermal storage and (c) an auxiliary gas heating unit, ensuring the solar thermal plant provides the high pressure side feed water preheating duty at all times without requirement to withdraw any steam from the power plant turbine circuit. A total of 230MWth is provided from the solar thermal plant installation, being 100% supply for high pressure and intermediate feed water preheaters duty plus a surplus of 30% for maintaining the deaerator operation. A key feature here is trying to eliminate the frequent changes to the steam flow rate in the turbine circuit for solar feed water preheating and thus promoting ease of retrofit of repowering technology to PCC-retrofitted power plants. Details of the component sizing and modelling of solar thermal installation are provided and control and operating schemes are identified and analysed. A comprehensive dynamic model in TRNSYS dynamic modelling software is developed and used to analyse the solar thermal plant dynamic responses to external disturbances including climatic changes (Typical Meteorological data for Sydney is used). The analysis limitations and capabilities are highlighted. The model performance for month December is assessed showing its full capability to track the changes from power plant duty requirement and meteorological data within the time lapse of 0.01s.