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A systematic procedure of experiments, performing simulation in conjunction with work measurement techniques, is introduced and aimed at undergraduate students in Industrial Engineering (IE) to learn a basic procedure for designing and implementing takt production in terms of the Toyota Production Systems (TPS). Students are split into small groups in a class. A series of experiments is designed and performed for an assembly line of magnetic contactors. Using the concept of the TPS, students perform work measurement studies including time study, process design, such as line balancing, and execute simulation experiments. At the end of the course, the teaching staff evaluates each group based on the performance of the simulation results. [ABSTRACT FROM AUTHOR]

The present study aims to develop a skeletal mechanism for multi-component fuel oxidation of diesel, biodiesel blended with short chain oxygenated fuels of ethanol and DMC. Starting from a detailed reaction mechanism, a reduced chemical kinetics which could treat both ethanol and DMC oxidation reactions was first developed using directed relation graph with error propagation and sensitivity analysis (DRGEPSA) method, and it was then combined with a tri-component biodiesel reaction mechanism developed in our previous study with CO, NOx and soot emission sub-models embedded. The final mechanism comprises 132 species and 617 elementary reactions. Extensive validations were performed for the developed skeletal mechanism through ignition delay testing and 3-D engine simulations. Validation results discerned that for ethanol, DMC and diesel fuels, predicted ignition delay time agreed very well with the detailed reaction mechanism or experimental results over a large range of initial pressure, temperature and equivalent ratio conditions with the maximum deviation below 25%, whereas for biodiesel, the largest discrepancy was 53%. 3-D engine combustion simulations also demonstrated that the ignition delay, cylinder pressure and heat release rate of diesel, biodiesel and their blend fuels with DMC could be very well reproduced by the present mechanism with reliable accuracies under various engine operating conditions. [ABSTRACT FROM AUTHOR]

A recently constructed cyclotron magnet at the Institute of Modern Physics of Chinese Academy of Sciences (IMPCAS) will be used as the injector of Heavy Ion Therapy Facility in Lanzhou (HITFiL). The diameter of the magnet is 2.92 m and its height is 1.52 m. The total weight of the magnet is 70 tons. The isochronous magnetic field for \q/m = 5/12 is achieved by appropriate pole edge profile. The paper discusses the various design and fabrication aspects of the magnet. The paper also presents the field measurement results and its comparison with simulation. [ABSTRACT FROM PUBLISHER]

Abstract: For the study of ground-borne vibration from surface sources, it is commonly assumed that soil properties remain constant with depth. However, various studies in the field of geotechnical engineering have shown that soil properties (stiffness and damping) change with depth due to the effect of increasing confining stress. Ground-borne vibration is hence unrealistically simulated if constant soil properties are assumed throughout a half space or a soil layer. This paper presents a study of the effect of the variation of soil properties with depth, referred to as soil non-homogeneity, on ground-borne vibrations induced by surface sources. The study involved physical modelling using a geotechnical centrifuge and numerical modelling using EDT and FLAC to gain further understanding of experimental results. In the centrifuge model, a dynamic excitation was applied to a rigid foundation resting on the surface of sand within a cylindrical container. Dynamic soil response was measured using accelerometers on the surface and within the soil. Comparison of the experimental and numerical results demonstrated that it is important to account for the variation of soil properties with depth when studying ground-borne vibration from surface sources. [Copyright &y& Elsevier]

Spaceborne synthetic aperture radar (SAR) plays more and more important role in Earth observation science, especially with ScanSAR mode which provides wide-swath coverage with moderate resolution. However, scalloping and inter-scan banding (ISB) are two major artifacts, which significantly degrade the quality of ScanSAR images. In this paper, a novel technique for removal of scalloping and ISB in ScanSAR images is proposed. Scalloping and ISB artifacts are modeled by two-dimensional gain and offset parameters varying as function of both azimuth time and range position. The gain and offset parameters can be split into azimuth and range components. The variations of gain/offset with respect to azimuth and range positions would represent scalloping and ISB artifacts respectively. In the proposed technique, recursive and minimum mean square error (MMSE) estimates of azimuth gain/offset parameters are found out by using Kalman filter for each azimuth location in a subswath by considering corresponding range samples as observation vector. Subsequently, range gain/offset parameters causing ISB artifacts are estimated by using Kalman filter for each range positions by considering azimuth samples as observation vector. The MMSE estimates of gain/offset parameters are used to directly remove scalloping and ISB artifacts. The proposed scheme was applied on simulated as well as calibrated real ScanSAR images. The experimental results exhibited the potential of proposed technique to be used as post processing tool for enhancing ScanSAR image quality. [ABSTRACT FROM AUTHOR]

Recent research has shown that using a mobile element to help enhance energy efficiency is popular. A mobile element can move in a sensed area to provide connectivity and collect sensed data. However, the mobile element can only travel over a portion of a sensor network under temporal constraints. To have better energy saving of WSNs, the authors plan rendezvous points for a mobile element to travel by mapping sensors in a plane to a point on a Halin graph. Using the Halin graph helps solve rendezvous planning in polynomial time. The simulation results show the merits of the proposed method. [ABSTRACT FROM AUTHOR]

Abstract: Water shortages and quality deterioration are serious dilemmas for lake managers as both problems sharply decrease the ecosystem services and functions provided by a lake. In this paper, using WASP as a tool, we have established and calibrated a water quality simulation model for Baiyangdian Lake and then analyzed water quality variations in scenarios with different pollution load reductions and different environmental flow releases into the lake and discovered the sustainable schemes for environmental flow management. From the results, in the scenarios of 30%, 50%, and 90% pollutant load reduction, the sustainable environmental flows are 3.52, 3.13, and 2.12 m3/s, and the corresponding lake levels could attain 7.45 m, 7.35 m, and 7.05 m from the initial 6.0 m. The obtained results indicated that water release could improve the lake volume and quality simultaneously. [Copyright &y& Elsevier]

A new extended application of kernel Fisher discriminant (KFD), i.e., KFD-based multiclass synthetical discriminant analysis (KFD-MSDA), is proposed for multi-target discrimination by using the traditional KFD 'one-against-one', and for multi-target classification under the proposed minimum synthetical Euclidian distance (MSED) rule. Theoretical analysis and experimental results on the measured and simulated radar HRRP databases indicate that, compared with several classical kernel-based methods, KFD-MSDA not only performs better with more stable recognition, but also keeps lower training time consuming and competitive recognition speed. [ABSTRACT FROM AUTHOR]

Combustion of solid fuel supplies heat in an iron ore sintering bed and the quality and productivity of the processes are highly dependent on the variation of operational parameters. To set the optimized operation modes through the application of various ideas, a numerical model can be employed prior to the conceptual designing of the actual plant. In this study, the effects of oxygen enrichment, increment of bed height, waste gas recirculation, as well as supplementary gaseous fuel combustion are investigated by employing a previously developed unsteady one-dimensional model of an iron ore sintering bed. Through the simulation, temperature distribution can be observed and used as the key data for the evaluation of the combustion efficiency. Flame front speed and sintering time, which represent propagation speed of the combustion zone, are also employed for quantification of the simulation. Through the parametric studies with numerical analysis, preliminary information about the detailed situation in the bed can be obtained. [ABSTRACT FROM AUTHOR]

Meteorological observations over the Tibetan Plateau (TiP) are scarce, and precipitation estimations over this remote region are difficult. The constantly improving capabilities of numerical weather prediction (NWP) models offer the opportunity to reduce this problem by providing precipitation fields and other meteorological variables of high spatial and temporal resolution. Longer time periods of years to decades can be simulated by NWP models by successive model runs of shorter periods, which can be described by the term "regional atmospheric reanalysis". In this paper, we assess the Weather Research and Forecasting (WRF) models capacity in retrieving rain- and snowfall on the TiP in such a configuration using a nested approach: the simulations are conducted with three nested domains at spatial resolutions of 30, 10, and 2 km. A validation study is carried out for a one-month period with a special focus on one-week (22-28 October 2008), during which strong rain- and snowfall was observed on the TiP. The output of the model in each resolution is compared to the Tropical Rainfall Measuring Mission (TRMM) data set for precipitation and to the Moderate Resolution Imaging Spectroradiometer (MODIS) data set for snow extent. TRMM and WRF data are then compared to weather-station measurements. Our results suggest an over- all improvement from WRF over TRMM with respect to weather-station measurements. Various configurations of the model with different nesting and forcing strategies, as well as physical parameterisation schemes are compared to propose a suitable design for a regional atmospheric reanalysis over the TiP. The WRF model showed good accuracy in simulating snow- and rainfall on the TiP for a one-month simulation period. Our study reveals that there is nothing like an optimal model strategy applicable for the high-altitude TiP, its fringing high-mountain areas of extremely complex topography and the low-altitude land and sea regions from which much of the precipitation on the TiP is originating. The choice of the physical parameterisation scheme will thus be always a compromise depending on the specific purpose of a model simulation. Our study demonstrates the high importance of orographic precipitation, but the problem of the orographic bias remains unsolved since reliable observational data are still missing. The results are relevant for anyone interested in carrying out a regional atmospheric reanalysis. Many hydrological analyses and applications like rainfall-runoff modelling or the analysis of flood events require precipitation rates at daily or even hourly intervals. Thus, our study offers a process-oriented alternative for retrieving precipitation fields of high spatio-temporal resolution in regions like the TiP, where other data sources are limited. [ABSTRACT FROM AUTHOR]

This paper presents our study on differential pressure sensors realized with magnetic liquids. We illustrate our work using a "U" tube type magnetic liquid sensor model and the corresponding experimental setup. Three major efforts are: developing the mathematical model describing the dynamic characteristic of the sensor based on the first law of thermodynamics, conducting FE simulation of electromagnetic field with magnetic liquids, and performing experimental implementation and examination using a non-magnetic based differential pressure sensor purchased. Experimental observation indicates a good agreement between the step-response and random response given by the developed magnetic liquids based sensor and the purchased non-magnetic liquids based sensor. [ABSTRACT FROM AUTHOR]

The capability of six two-equation Reynolds-averaged Navier-Stokes (RANS) models for simulation of a non-swirl coal flame in a pilot-scale furnace has been investigated. These turbulence models—the standard k-ε model, re-normalization group (RNG) k-ε model, modified k-ε model, Wilcox k-ω model, Menter k-ω model (also called BSL model), and Shear-stress transport (SST) model—are assessed with the use of measured gas phase velocity, temperature, oxygen, and carbon dioxide volume fraction data from the literature. Predictions of the standard k-ε model, RNG k-ε model, BSL, and SST model are generally in good agreement with the experimental data. The Wilcox k-ω model generally overpredicts O2 volume fraction and underpredicts CO2 volume fraction. The modified k-ε model yields results that have large discrepancies from measurements. [ABSTRACT FROM AUTHOR]

This study was carried out to develop a two-layered finite element model of the oesophagus. The outer muscle and inner mucosal layer were constructed individually with different mechanical properties and zero-stress opening angles. With the model, two simulations were performed. First, the distention of oesophageal wall under the pressurized state was investigated, from which the effects of residual strains on the stress distribution were evaluated. Second, the buckling modes were determined using a linear eigenvalue analysis. The self-contact capability in ABAQUS was applied to simulate the folding of mucosa under the muscle contraction. The first simulation indicated that, by taking the residual strains into account, the mucosa undertook a very small portion of stress and the luminal pressure almost transmitted completely to the outer muscle layer. On the other hand, the folding of mucosa was shown to be able to reduce the contractile force of circular muscle to maintain the lumen closure. In conclusion, the preliminary study demonstrated the feasibility of simulating the oesophageal peristaltic transport using finite element analysis. [ABSTRACT FROM AUTHOR]

The purpose of the present study is to develop a numerical model for the investigation of water waves propagating over a pair of impermeable submerged obstacles. The mathematic model is formulated by coupling solutions of the Navier–Stokes equations and transport equations for the surface elevation using the volume of fluid method. Based on a staggered computational mesh, an explicit numerical algorithm is employed with a predictor–corrector procedure of pressure and velocity field. The proposed model provides good agreement with other experimental results and validates its good performance. Regarding the spatial harmonic evolutions of various cases, it is noted that the present fluctuating mode of harmonic amplitudes exists upstream and at the gap between obstacles. The results show that the nonlinearity of propagating waves becomes stronger than the initial wave in such areas, and reveals much steeper wave profiles compared to the initial ones. The fluctuating harmonic amplitudes vary with the gap width and form two hydrodynamic cycles. The vortices play an important role in the wave reflection as they form a water column wall to reflect the incoming waves. The reflection ratio depends on the extent of vortex development near the upstream obstacle. The maximum wave reflection occurs in cases with dimensionless gap width S/L equal to 3/8 and 7/8 in this study. [ABSTRACT FROM AUTHOR]

Abstract: We propose a new multiscale simulation method which seamlessly combines the conventional molecular dynamics (MD) with the continuum mechanics formulated under the material point method (MPM). In MPM, modified interpolation shape functions are adopted to reduce artificial forces on the hierarchical background grids. The multiscale method is validated using the examples of step-like wave and wave packet propagations within a bar. The method is applicable to several kinds of potentials including the Lennard–Jones, EAM and a bonding-angle related potential for silicon. Examples of high energy Cu–Cu and Si–Si cluster impacts are presented. The evolution of displaced atoms is found to depend on the underlying lattice structures. For the case of Cu–Cu cluster impacts, stacking faults play an important role. The displaced atoms, visualized in the method of “local crystalline order”, propagate in an anisotropic manner. This implies the anisotropy in energy transformation process through multi-interactions among cluster and surface atoms. [Copyright &y& Elsevier]

Transformations of organic matter, nitrogen and sulfur in sewers can be simulated taking into account the relevant transformation and transport processes. One objective of such simulation is the assessment and management of hydrogen sulfide formation and corrosion. Sulfide is formed in the biofilms and sediments of the water phase, but corrosion occurs on the moist surfaces of the sewer gas phase. Consequently, both phases and the transport of volatile substances between these phases must be included. Furthermore, wastewater composition and transformations in sewers are complex and subject to high, natural variability. This paper presents the latest developments of the WATS model concept, allowing integrated aerobic, anoxic and anaerobic simulation of the water phase and of gas phase processes. The resulting model is complex and with high parameter variability. An example applying stochastic modeling shows how this complexity and variability can be taken into account. [ABSTRACT FROM AUTHOR]

Spatially evolving turbulent mixing layers are investigated in this paper using large eddy simulation. The evolutions of large vortex structures are obtained, in which the processes of vortex roll up, growth, pairing and breaking up are shown in details. The simulated flow patterns agree well with experimental visualization results. Predicted results of mean properties of streamwise velocity, fluctuating velocity and Reynolds stress at different sections show good self-similarity and agree well with experimental measurements. Linear growth of the momentum thickness along the streamwise direction is then obtained, indicating that pairing and amalgamating of large vortex structures in plane mixing layers occur randomly in space and time. The effects of convection velocity and the rate of shear on the evolution of vortex structures, self-similarity as well as momentum thickness are also investigated. The rate of shear has a significant effect on the evolution of coherent structure and the slope of momentum thickness growth, while the convection velocity only affects the space interval of the adjoining vortices. The rate of shear and convection velocity have no significant effect on the non-dimensional distributions of turbulence statistics. Self-similarities are therefore obtained for different rates of shear and convection velocities. [ABSTRACT FROM AUTHOR]

Electrical capacitance tomography (ECT) has been developed for imaging dielectric material distributions. While iterative image reconstruction algorithms may produce high-quality images, they are regarded as being time-consuming and currently can only be used offline. This paper describes a new image reconstruction algorithm for ECT. First, a coefficient matrix is generated through an offline iteration process. The matrix is then used for online image reconstruction in the same way as a sensitivity map is used in the popular linear back-projection (LBP) algorithm. This new algorithm can produce similar quality images to the Landweber iteration algorithm, but at the same speed as the LBP. An optimal step-length has been incorporated into the new algorithm for improved convergence. The algorithm has been evaluated by both simulation and experiment. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a numerical study of a gas-particle flow in three inclined rectangular jets in crossflow. The predicted gas phase velocities and particle phase velocities are validated against previously reported experimental data. Two turbulence models, the standard k–ɛ model and Shear Stress Transfer (SST) model, are used to model the gas phase turbulence. This work shows that both models provide acceptable predictions of the gas flow and mixing generated by the three jets. Neither model could accurately reproduce the jet core and the flow near bottom wall. The particle phase in this flow comprises a large number of small particles. Thus particles follow the gas phase flow closely and any errors in the turbulence model and gas flow predictions are passed on to the particle phase simulation. This paper also includes a literature review on rectangular jets in crossflow and gas-particle laden jets in crossflow. [Copyright &y& Elsevier]

The USDA Soil Conservation Service (SCS) curve number (CN) method has been the foundation of the hydrology algorithms in commonly used continuous simulation models, including the Soil and Water Assessment Tool (SWAT). This expanded use of the SCS-CN method has proven successful for many applications. However, because the SCS-CN method was originally developed to determine design peak discharges of synthetic storm events under an average antecedent moisture condition, research is needed to address the controversy over the use of this method to represent continuous precipitation runoff processes. In addition, poor results obtained for some conditions indicate the necessity to improve the method to provide a more realistic and accurate representation of waterflow amounts, paths, and source areas upon which erosion and water quality predictions depend. Thus, the objectives of this study were to: (1)propose a modified curve number (MCN) method, and (2) assess the MCN method relative to the existing SWAT method with an Ia/S value either equal to 0.2 or 0.05. The equations that formulate the MCN method were coded into the SWAT 2005 framework. A SWAT model implementing the MCN method was evaluated along with the models implementing the existing SWAT method with Ia/S values of 0.2 and 0.05. The evaluation was conducted in the 870 km² upper portion of the Forest River watershed located in northeastern North Dakota. The results revealed that the total streamflows predicted by the three models were comparable, as indicated by similar values for the Nash-Sutcliffe coefficient. However, the MCN approach resulted in the most accurate prediction of the streamflow components (i.e., baseflow versus direct flow) as well as water yields. For the study area, the MCN method was judged to be superior to the existing commonly used curve number methods in terms of mimicking the precipitation runoff processes. [ABSTRACT FROM AUTHOR]

Abstract: Effective nasal drug delivery is highly dependent on the delivery of drug from the nasal spray device. Atomisation of liquid spray occurs through the internal atomizer that can produce many forms of spray patterns and two of these, hollow-cone and full-cone sprays, are evaluated in this study to determine which spray pattern produced greater deposition in the middle regions of the nasal cavity. Past studies of spray particle deposition have ignored the device within the nasal cavity. Using computational fluid dynamics (CFD), two computational models of human nasal cavity model were reconstructed from CT-scans, where the difference between the two models was the presence of the nasal spray device accounting for the airway blockage at one of the nostrils. Experimental measurements from Particle Droplet Image Analyser (PDIA) were taken in order to gain confidence in determining the initial particle conditions for the computational models. An airflow field is induced through a negative pressure flow condition applied at the pharynx instead of constant flow rates at the left and the right nasal cavities. Subsequent airflow patterns and its effects on particle deposition, with and without a spray device, are compared. Contours and streamlines of the flow field revealed that the presence of a spray device in the nasal vestibule produced higher levels of disturbed flow, which helped the dispersion of the sprayed particles. Particle deposition was found to be high in the anterior regions of the nasal cavity caused by its inertia. Evaluation of the two spray types found that hollow spray cones produced more deposition in the middle regions of the nasal cavity. This paper also demonstrates the CFD methodology used, which can help in better understanding the design of future atomizers for nasal spray use. [ABSTRACT FROM AUTHOR]

Abstract: The kinetics and thermodynamics of normal grain growth can be linked by two open questions. Is it physically practicable to incorporate the grain boundary (GB) energy decrease with GB segregation into the parabolic kinetics of grain growth? Subsequently, how can a model for grain growth that considers the mixed effect of kinetics and thermodynamics be derived? Departing from Borisov’s equation, a qualitative description is provided to validate the incorporation of GB energy into the grain growth kinetics. Then, a thermokinetic model considering the mixed effect of solute drag and reduced GB energy is developed. Subjected to specific limitations, the thermokinetic model reduces to a purely kinetic model, a purely thermodynamic model and a model considering only grain-size-dependent solute drag. By application of the model to experimental results obtained from nanocrystalline Ni–P and oxygen-doped nickel, it has been shown that the effect of solute drag could retard but not stop the grain growth, and that the main cause of a stabilized nanocrystalline structure is not the solute drag but the reduction in GB energy. [Copyright &y& Elsevier]

Abstract: The electrochemical reaction induced resistance switching of memory cells based on solid electrolyte is simulated by an interface-tracking method using a two-dimensional model. For the switching-on process, the simulating results show that metal dendrites will be formed in the solid electrolyte, switching the device to a low-resistance state. For the switching-off process, the dendrite will be dissolved and the conductive channel eventually breaks down, switching the device to a high-resistance state. [Copyright &y& Elsevier]