Performance analysis of a denitrifying wastewater treatment plant

The cleaning performance of an activated sludge wastewater treatment plant for biological nitrogen removal was evaluated based on the Activated Sludge Models No. 1 (ASM1) and No. 3 (ASM3). The COST predenitrification benchmark plant was considered as a case study. Several treatment plant performance indexes were defined based on performance indicators and operating cost factors. Plant operation was evaluated for three dynamic disturbance scenarios corresponding to dry, rain, and storm weather conditions. The aeration rate was seen to be the most sensitive process parameter for this case study, and the nitrate recycle flow rate ratio was the least sensitive of all parameters analyzed. Different qualitative predictions were obtained from the two models, as a result of different model structures. For all three weather scenarios, the sludge production predicted by the ASM1 model increases slightly as the oxygen transfer rate increases; in contrast, the sludge production decreases for the ASM3 model. However, the resulting difference in the sludge treatment cost does not qualitatively modify the cost performance index profile. For all control handles considered the rain weather scenario showed the highest cost performance index and the lowest global cleaning efficiency. Electronic Publication     

Computer aided analysis of strain rosette data

In this paper a computer program has been developed for analysing the strain gauge rosettes by considering the transverse sensitivity of all gauges. The program is capable of calculating principal strains, maximum shear strain, principal stresses, maximum shear stress and principal directions from the data obtained by using strain gauge rosettes of various configurations. The gauge factor and transverse sensitivity of all gauges in the rosette must be the same.     

Ultraviolet disinfection application to a wastewater treatment plant

Considering most benefits of using ultraviolet (UV) radiation, the Lacey, Olympia, Tumwater and Thurston County (LOTT) wastewater treatment plant located in the City of Olympia was the first major POTW on the U.S. West Coast to install and successfully operate a UV disinfection system that processes about 22 MGD of wastewater. The LOTT's secondary treatment process is a biological nutrients removal system, and has the capabilities of removing more than 90% total suspended solids (TSS), biological oxygen demand, and nutrients (including phosphorus). This high quality effluent with low TSS contributes to achieving a highly efficient UV disinfection system with monthly geometric mean values in the range of 4–48 fecal coliform per 100 ml, well below the NPDES permit limit set to 200 counts per 100 ml. This paper summarizes the results and conclusion from the pilot study conducted at LOTT prior to installing a full-scale UV system, with references to other updated work reported elsewhere. Electronic Publication     

Computer aided circuit analysis and design projects for electronicengineering students

The integration of circuit simulation programs into an undergraduate electronics curriculum is discussed. Several projects are presented which combine application of a computer package with corresponding practical experiments in the electronics laboratory. In this way, students learn that electronic circuits are not simply blackboard theory but tangible objects which only given the optimum performance predicted by theoretical analysis following a careful design, simulation and test. Furthermore, some ideas for diploma thesis projects are presented, which offer students an opportunity to understand better the limitations of the software package and to extend its capabilities to new applications     

Neural network-based multi-back-propagation prediction model of a domestic wastewater treatment plant for an under-construction sewer system

When the sewer collection of a serviced area has not reached the full design capacity of the domestic wastewater treatment plant, mathematical models have the potential to provide useful information for operating the plant to meet discharge standards and managing the received water system. In this article, a back-propagation neural network (BPNN) was applied for predicting wastewater quantity and quality. Three basic models are included in this network, i.e., A1(PIQQ) for predicting influent quantity and quality, A2(PEQQ) for predicting effluent quantity and quality, and A3(PQWCWS) for predicting the quantity and water content of waste sludge. The multi-model (A1?+?A2) system that combines A1 and A2 into a noted multi-BPNN (MBPNN) is used for estimating A2 output parameters directly based on A1 input parameters. The correlation coefficient values (R) are higher than 0.95 for A1, whereas the mean absolute percentage errors are less than 35% for A2 and A3, and 46% for A1?+?A2. These results indicate that BPNN and MBPNN are suitable for predicting the wastewater quantity and quality especially for Q, BOD₅, sludge quantity, and water content in an under-construction sewer system.     

Computer aided materials selection and design

The design of an end-product and the choice of the material from which it should be made are interdependent activities which nevertheless have separate and different requirements for supporting data. The provision of such data is not quite as straightforward as it might seem at first sight, mainly because the properties of a moulded item vary from point to point and differ from the properties exhibited by idealized specimens. At the very least this complicates the task of evaluation and on occasions it leads to the charge that the data provided bear little relation to service performance, but such situations are common whenever complex materials are used in exacting applications and are in no sense peculiar to plastics and the automotive industry which are the focus of this paper. Our comprehension of the materials is continually enhanced by new research results and the means by which that comprehension can be translated into data of value to the end-user industries improve in step with the advances in computer technology.One can now envisage an efficient flow of pertinent data across the interface between the end-user industries and the plastics industry. The first steps towards that ideal were discussed in two papers presented at SITEV 79^1,2; they described new results emerging from work in the research laboratories of thee Plastics Division¹ of ICY that offered a possible route to data that are both more concise and more relevant to downstream applications than earlier data described ways in which such data and more iraditional information can be manipulated by computer and “tailored” to the specific needs of particular users. This new paper develops that theme further and possibly marks the point at which responsibility for later developments should pass from research workers to those professionally concerned with the transfer of information from one group to another, for there now exists a prototype data system. The only issues to be resolved now are what information should be incorporated rather than how should the task be done. The paper is concerned primarily with the data and the underlying rationale rather than with the software that controls the various operations.     

Computer model simulation study of nanocrystalline iron

This paper provides a computer modelling technique, associated with the molecular statics relaxation method, for the study of nanostructured crystals. Atomistic simulations have been carried out to study the structural features of nanocrystals, such as the reduced mass density, the boundary component proportion, the excess lattice parameter, the excess atomic volume and the radial distribution function. The energy and elastic properties also have been investigated. The simulated results have shown considerable agreement with the experimental results, which implies that the present modelling method is suitable to be used to study the structures and properties of nanocrystals.     

Analytical and numerical treatment of a dynamic crack model

We discuss the propagation of a running crack in a bounded linear elastic body under shear waves for a simplified 2D-model. This model is described by two coupled equations in the actual configuration: a two-dimensional scalar wave equation in a cracked, bounded domain and an ordinary differential equation derived from an energy balance law. The unknowns are the displacement fields u  =  u(y, t) and the one-dimensional crack tip trajectory h  =  h(t). We assume that the crack grows straight. Based on a paper of Nicaise-Sändig, we derive an improved formula for the ordinary differential equation of motion for the crack tip, where the dynamical stress intensity factor occurs. The numerical simulation is an iterative procedure starting from the wave field at time t  =  t _i . The dynamic stress intensity factor will be extracted at t  =  t _i . Its knowledge allows us to compute the crack-tip motion h(t _i+1) with corresponding nonuniform crack speed assuming (t _i+1 ? t _i ) is small. Now, we start from the cracked configuration at time t  =  t _i+1 and repeat the steps. The wave displacements are computed with the FEM-package PDE2D. Some numerical examples demonstrate the proposed method. The influence of finite length of the crack and finite size of the sample on the dynamic stress intensity factor will be discussed in detail.     

多自由度刨煤机动力学模型的建立与仿真

在单自由度刨煤机动力学模型的基础上,根据刨煤机的实际运行工况,建立了刨煤机多自由度非线性动力学模型,其中考虑了随机的煤壁作用力、刨链预紧力、链轮多边形效应因素的影响。并采用MATLAB/Simulink进行数值求解和仿真,得到了在各因素影响下刨头速度和刨链张力的变化状态。结果表明随机煤壁作用力和刨链预紧力对刨头速度和刨链张力变化的影响较大,链轮多边形效应影响较小,并且随机的煤壁作用力弱化了链轮多边形效应的影响。对多自由度和单自由度刨煤机动力学模型进行了比较分析,得出各种因素的影响规律是一致的,多自由度动力学模型更符合实际工况。为分析刨煤机动力学问题以及提高刨链可靠性提供理论基础。     

基于LabVIEW的纳米颗粒动态散射光模拟

采用实验室虚拟仪器工程平台LabVIEW实现了纳米颗粒动态光散射信号的计算机模拟。用G语言(图形语言)设计了信号模拟的框图程序,给出了5nm, 15 nm两种粒径颗粒的模拟动态散射光信号及自相关函数。对模拟信号的粒度分析表明,这两种模拟信号产生的测量偏差分别为0.4nm和-0.6nm。     

Computer aided diagnosis of brain abnormalities using texture analysis of MRI images

The drive of this study is to develop a robust system. A method to classify brain magnetic resonance imaging (MRI) image into brain-related disease groups and tumor types has been proposed. The proposed method employed Gabor texture, statistical features, and support vector machine. Brain MRI images have been classified into normal, cerebrovascular, degenerative, inflammatory, and neoplastic. The proposed system has been trained on a complete dataset of Brain Atlas-Harvard Medical School. Further, to achieve robustness, a dataset developed locally has been used. Extraordinary results on different orientations, sequences of both of these datasets as per accuracy (up to 99.6%), sensitivity (up to 100%), specificity (up to 100%), precision (up to 100%), and AUC value (up to 1.0) have been achieved. The tumorous slices are further classified into primary or secondary tumor as well as their further types as glioma, sarcoma, meningioma, bronchogenic carcinoma, and adenocarcinoma, which could not be possible to determine without biopsy, otherwise.     

单自由度刨煤机动力学模型的建立与仿真研究

根据刨煤机运行的工况,考虑煤给予刨头的刨削阻力为随机变化的量,建立了刨煤机单自由度非线性随机动力学模型,同时考虑了刨链预紧力、多边形效应因素的影响.并以某参数为实例利用MATLAB/Simulink进行数值求解和仿真,得到了各因素影响下刨头速度和刨链张力的变化.研究结果表明随机刨削阻力和刨链预紧力对刨头速度和刨链张力变化影响较明显,链轮多边形效应则影响较小.本研究为分析刨煤机运行和刨链可靠性提供依据.     

Computer aided design of quartz crystal oscillators

The latest development of a simulation program designed for quartz crystal oscillator analysis is presented in this paper. The simulator being developed uses the full nonlinear Barkhausen criterion method. It consists of finding the frequency ω₀ and the amplitude u₀ which nullify both the real and imaginary parts of a characteristic complex polynomial P(u,jω) describing the oscillator behavior. Most of the nonlinearities come from the amplifying transistor described by using large signal admittance parameters y(u) obtained by means of an analog circuit simulator (SPICE). This paper presents the method used to derive and code the characteristic polynomial coefficients. This method has been successfully implemented for a Colpitts oscillator and is currently being used to build an oscillator library covering the most widely used structures. The validity and the predictive power of the model have been checked experimentally and the comparison between experimental results and simulation is presented and discussed