Analytical modeling of steady-state filtration process in an automatic self-cleaning filter

The origins of modern spatial analysis lie in the development of quantitative geography and regional science in the late 1950s. The use of quantitative procedures and techniques to analyse patterns of points, lines, areas and surfaces depicted on analogue maps or defined by co-ordinates in two-or three-dimensional space characterise the initial stage. Later on, more emphasis was placed on the indigenous features of geographical space, on spatial choices and processes, and their implications for the spatio-temporal evolution of complex spatial systems. Spatial analysis, as it has become over the past four decades, is more than spatial statistics and data analysis, and goes far beyond data sampling, data manipulation, exploratory and confirmatory spatial data analysis, into areas of spatial modelling encompassing a large and diverse set of models in both the environmental and the social sciences. In the environmental sciences, they range from physical dispersion models (e.g. for suspended particulates), chemical reaction models (e.g. photochemical smog), and biological systems models (e.g. for ecosystems in water), through deterministic process and stochastic process models of regional environmental quality management, and integrated models for environment-energy-economic assessment. For many models, especially the physical dispersion models, chemical reaction models, and biological systems models, the geographical location of the site is not considered to be of overriding importance. The variation in model results over space can be achieved by obtaining different inputs to the area in question. Process models include deterministic versions which attempt to describe a particular sequence in terms of known physical laws, and stochastic model versions which aim to describe a particular process such as erosion, groundwater movement and absorption of pollutants in terms of probability theory. For such processes, there is an interaction between the spatial process and a substrate. This substrate provides a one-, two-or three-dimensional framework within which the process model can operate. The space in which the process is modelled is disaggregated into a set of finite elements which are usually assumed to be internally homogeneous. Two-dimensional models generally use as their data small pixels (see Fischer et al., 1996).

Computational and experimental studies on the efficient removal of diclofenac from water using ZnFe-layered double hydroxide as an environmentally benign absorbent

A common situation in chemical processes is that the measured data come from a dynamic process, but the available accurate process models only represent steady-state behavior. Furthermore, process data usually contain multiscale features due to different localizations in time and frequency. Existing methods for rectifying dynamic data require an accurate dynamic process model and are best for rectifying single-scale data. This paper presents a multiscale Bayesian approach for rectification of measurements from linear steady-state or dynamic processes with a steady-state model or without a model. This approach exploits the ability of wavelets to approximately decorrelate many autocorrelated stochastic processes and to extract deterministic features in a signal. The decorrelation ability results in wavelet coefficients at each scale that contain almost none of the process dynamics. Consequently, these wavelet coefficients can be rectified without a model or with a steady-state process model. The dynamics are captured in the wavelet domain by the scale-dependent variance of the wavelet coefficients and the last scaled signal. The proposed approach uses a scale-dependent prior for rectifying the wavelet coefficients and rectifies the last scaled signal without a model. In addition to more accurate rectification than existing methods, the multiscale Bayesian approach can eliminate the less relevant scales from the rectification before actually rectifying the data, resulting in significant savings in computation. This paper focuses on the rectification of Gaussian errors, but the approach is general and can be easily extended to other types of error distributions.

This paper investigates the transient pressure behavior of selectively completed horizontal wells. A new solution in Laplace space is presented and asymptotic approximations are derived. Computational issues are also addressed. Flow characteristics of sectionally completed horizontal wells are discussed and the information that can be obtained from the analysis of pressure and derivative responses during various flow regimes are documented. It is shown that the solutions existing in the literature cannot completely describe the essential features of flow toward a sectionally completed horizontal well.

A novel oil–water separator design and its performance prediction

Modeling of photodegradation process to remove the higher concentration of environmental pollution

Information and Communication Technology (ICT) offers in the learning process individual teaching approaches, knowledge gain in any place or time of individual preference, the ability to study a large number of subjects, the power to students and adults to control their learning process and finally the ability to gain knowledge on a number of subjects which through the traditional ways is impossible. All these factors make eLearning an attractive learning approach. This approach has been welcomed from the educational community, industry, commerce and from the community in general. A number of approaches for measuring learning systems cost-effectiveness through quantitative methods are used but this is not enough as learning represents a value by itself and this should be measured too.This study deals with the presentation of a simple and practical ROI model for the e-Learning process in an organisation.

<div class="htmlview paragraph">The measurement of the various pollutant species (HC, CO, NO, etc.) has become one of the main issues in internal combustion engine research. This interest concerns not only their quantitative measurement but also the study of the mechanism of their formation. In fact, pollutant species concentration can be used as an indicator for the combustion characteristics. For instance, it enables the determination of a lean or a rich combustion, the percentage of EGR, etc.</div> <div class="htmlview paragraph">The purpose of this research is to investigate the behavior of pollutant gas particles in the first part of an engine exhaust system through a detailed study of the unsteady flow in the exhaust pipe. The results are intended to designate the appropriate sensor positions which ensure accurate measurement results.</div> <div class="htmlview paragraph">This investigation wants to track an inert component in the exhaust system, namely the NO gas. This component can be considered as inert since its reaction freezes at temperatures which are higher than outside the cylinder. For this purpose a thermodynamic model of the in-cylinder process has been matched with a model for the fluid dynamics of the exhaust gas process to simulate the exhaust conditions.</div> <div class="htmlview paragraph">A set of simulations was performed for different working conditions of an engine. The simulated transient pressure field in the pipe has been compared with real data gathered on a V6 SI engine.</div>

Microscale processes of dust distribution in the city of Tbilisi with a very complex topography are modeled using a 3D regional model of atmospheric processes and numerical integration of the transport-diffusion equation of the impurity. The Terrain-following coordinate system is used to take into account the influence of a very complex relief on the process of atmospheric pollution. Modeling is carried out using horizontal grid steps of 300 m and 400 m along latitude and longitude, respectively. The cases of the stationary background eastern and western weak winds are considered. In the model, motor transport is considered as a nonstationary source of pollution from which dust is emitted into the atmosphere. Modelling of dust micro-scale diffusion process showed that the city air pollution depends on spatial distribution of the main sources of city pollution, i.e. on vehicle traffic intensity, as well as on spatial distribution of highways, and micro-orography of city and surrounding territories. It is shown that the dust pollution level in the surface layer of the atmosphere is minimal at 6 a.m. Ground-level concentration rapidly grows with increase of vehicle traffic intensity and by 12 a.m. reaches maximum allowable concentration (MAC = 0.5 mg/m3) in the vicinity of central city mains. From 12 a.m. to 9 p.m. maximum dust concentration values are within the limits of 0.9-1.2 MAC. In the mentioned time interval formation of the highly dusty zones, and slow growth of their areas and value of ground-level concentrations take place. These zones are located in both central and peripheral parts of the city. Their disposition and area sizes depend on spatial distribution of local wind generated under action of complex terrain, as well as on the processes of turbulent and advective dust transfer. From 9 to 12 p.m. reduction of dust pollution and ground-level concentration takes place. After the midnight city dust pollution process continues quasi-periodically. As result of the analysis of vertical distribution of dust concentration is obtained that a basic dust mass emitted into the atmosphere is located in the 100 m surface layer. Concentration value in the upper part of this layer reaches 0.8 MAC and rapidly decreases with altitude increase.

Modelling of precision steady-state and non-steady-state electrochemical machining by wire electrode-tool

The mechanism underlying the marked regional variations in blood flow within single skeletal muscles has not been identified. The present investigation was prompted by previous data pointing to a regional distribution of the number of perfused vessels as one possible determinant for the heterogeneous perfusion pattern. We examined this possibility by assessing the regional tissue uptake rates of vitamin B12 and albumin assuming that these are related to the number of perfused vessels. This is the first study that has included simultaneous measurements of regional blood flow and of regional tissue uptake rates of vitamin B12 and albumin within single skeletal muscles in the intact animal. The microsphere method was adopted to measure regional blood flow in 0.25 g muscle regions in awake and in anaesthetized rabbits. Various tracers were used to assess the regional distributions of tissue uptake rates and of vascular and interstitial volumes. Albeit displaying a marked regional heterogeneity, neither the tissue uptake rate of vitamin B12 nor that of albumin were correlated to regional blood flow (P less than 0.05) at rest (awake or anaesthetized rabbits) or during exercise hyperaemia (anaesthetized). At rest, but not during exercise, the distributions of regional tissue uptake rates of the two tracers showed a striking bimodal pattern. Vascular and interstitial volumes showed minimal interregional variations. The lack of correlation between regional blood flow and tissue uptake rates and the minute interregional variation in vascular volume, argue against variations in the number of perfused vessels as the explanation for the regional heterogeneity in blood flow.

The nuclear heating reactor (NHR), which is independently developed and designed by Tsinghua University, adopts full power natural circulation and has the characteristic of low mass flow rate. Due to the different operating conditions between NHR and PWR, it is necessary to analyze the thermal hydraulic performance of the fuel assembly in NHR core. The thermal hydraulic performance of the fuel assembly is mainly analyzed by the subchannel analysis code which can accurately calculate the two-phase parameters. Therefore, this research employs subchannel analysis code COBRA-TF to simulate radial uniform and non-uniform heating assembly under the operating conditions of low mass flow rate from 300kg/m2s to 700kg/m2s. The simulations are validated on the thermal hydraulics experiments of GE and Studsvik. The result shows that the calculated mass flow rate and void fraction are in good agreement with the experimental results. Under radial nonuniform heating condition, high outlet mass velocity appears in low heating power region, while the high outlet void fraction appears in high heating power region. Compared with the uniform heating condition, the distribution of the mass flow rate and the void fraction in subchannels under non-uniform heating conditions varies greatly. In addition, the transverse flow and the counterflow also can be observed in non-uniform heating conditions under low mass flow rate conditions. The appearance of such transverse flow mainly results from the radial pressure difference, rather than the turbulent mixing and void drift. Therefore, it is essential to predicate the distribution of the mass flow rate and the void fraction under non-uniform heating and low mass flow rate conditions.

Using results of groundwater flow system modeling for a hypothetical deep geological repository site, a distribution of groundwater flow rates at the disposal depth was analyzed and a method of applying this distribution to a safety assessment for a disposal of radioactive wastes was suggested. The distribution of groundwater flow rates was produced by hydraulic heads simulated from regional and local scale groundwater flow models for the hypothetical disposal site. The flow rates at the locations where deposition holes would be located were estimated. These rates were normalized by the maximum of the flow rates in order to probabilistically illustrate a possibility of canister failures at the deposition holes. From the normalized distribution, probabilistic expectations for mass discharges of radionuclides released from the canisters assumed to be failed were calculated and compared with those deterministically estimated under the assumption that the canisters at the same deposition holes were definitely failed. The suggested method can be contributed to constructing a methodology for safety assessment of a geological repository by reflecting natural conditions of a disposal site in more detail.

Numerical analysis of ABS deposition and corrosion on a rotary air preheater

An experimental study was made on the methods to control the distribution of flow rate into branch tubes in a multitube heat exchanger. The distribution of flow rate was strongly dependent upon the direction and the dynamic pressure of the water jet from an inlet nozzle. In this experiment, a circular plate or a flat plate with a large circular or rectangular hole was set downstream from the nozzle to modulate the dynamic pressure of the water jet. The results show that the properly determined dimensions and position of the circular or the rectangular plate were useful to render the flow rate distribution uniform. Also, a circular plate with many small holes had a better effect.