Measurement of the velocity of products of combustion in gas-fired heaters

A relatively simple scheme is presented for measuring the velocity in an environment such as the flue way of gas-fired furnaces and heaters. The scheme employs a measure of the correlation between two thermocouples displaced in the axial direction. Analysis of the time-delayed correlation between these two signals shows a maximum value of the correlation function at a delayed time which corresponds to the transit time between both sensors. Knowledge of the separation between these sensors permits a measure of the velocity. While the accuracy of the device may be on the order of 10%, the procedure is straightforward and simple, requires no calibration, and is not dependent on the local properties of the fluid.     

On the calculation of autoresonance vibroimpact systems perturbed by random forces

The investigation into autoresonance vibroimpact systems is continued. As an example, the system containing the sensor for impact pulses is selected. The main purpose of the study is to the calculation procedure for systems in the presence of small random perturbations. The corresponding calculation procedure based on the determination of fluctuation corrections obtained by the averaging method is given. Examples of calculations for two types of perturbations, namely, small random forces of the white noise type and the forces with a short correlation time are presented. The solutions have a clear mechanical interpretation.     

Polarity of the 14-strand fibers of sickle cell hemoglobin determined by cross-correlation methods

Images of negatively stained fibers of sickle cell hemoglobin have been analyzed by cross-correlation methods. These methods are used to compensate for the curvature and variable repeat distance characteristic of negatively stained fibers. Averaged images obtained by the correlation procedure display considerably more detail than the filtered images obtained earlier by Fourier methods. The averaged images are sufficiently detailed that the back-projection method for obtaining cross-sections can now be applied directly to the correlation-averaged images. This method was used previously to deduce the 14-strand structure on Fourier-filtered images that incorporated only the near-equatorial maxima. In this way the 14-strand structure has been reconfirmed without utilizing the partial Fourier reconstructions employed earlier that might conceivably have introduced spurious features. In addition, application of the correlation procedure with and without inversion of the reference reveals a consistent polarity in all of the fibers examined. The confirmation of the 14-strand structure by a new procedure and the determination of fiber polarity would appear to eliminate the alternative model of the fibers with a 16-strand structure with equal numbers of strands (eight) of each polarity.     

Noise bias in the refinement of structures derived from single particles

One of the main goals in the determination of three-dimensional macromolecular structures from electron microscope images of individual molecules and complexes (single particles) is a sufficiently high spatial resolution, about 4 A, at which the interpretation with an atomic model becomes possible. To reach high resolution, an iterative refinement procedure using an expectation maximization algorithm is often used that leads to a more accurate alignment of the positional and orientational parameters for each particle. We show here the results of refinement algorithms that use a phase residual, a linear correlation coefficient, or a weighted correlation coefficient to align individual particles. The algorithms were applied to computer-generated data sets that contained projections from model structures, as well as noise. The algorithms show different degrees of over-fitting, especially at high resolution where the signal is weak. We demonstrate that the degree of over-fitting is reduced with a weighting scheme that depends on the signal-to-noise ratio in the data. The weighting also improves the accuracy of resolution measurement by the commonly used Fourier shell correlation. The performance of the refinement algorithms is compared to that using a maximum likelihood approach. The weighted correlation coefficient was implemented in the computer program FREALIGN.     

A systematic procedure for determining the chiral indices of multi-walled carbon nanotubes using electron diffraction--each and every shell

Electron diffraction technique has been developed and refined to establish a systematic procedure to determine the chirality (chiral indices) of each and every shell in a carbon nanotube. We have introduced a zoning scheme to sort the reflection layer lines from the multiple shells of a carbon nanotube. An application of the procedure is demonstrated as an example for an eleven-shell carbon nanotube whose chiral indices of each and every shell were determined unambiguously. The revealed structure of the carbon nanotube suggests that there is no strong correlation among the shells as the nanotube was formed. The limitations of the current method are also discussed.     

A systematic procedure for determining the chiral indices of multi-walled carbon nanotubes using electron diffraction—each and every shell

Electron diffraction technique has been developed and refined to establish a systematic procedure to determine the chirality (chiral indices) of each and every shell in a carbon nanotube. We have introduced a zoning scheme to sort the reflection layer lines from the multiple shells of a carbon nanotube. An application of the procedure is demonstrated as an example for an eleven-shell carbon nanotube whose chiral indices of each and every shell were determined unambiguously. The revealed structure of the carbon nanotube suggests that there is no strong correlation among the shells as the nanotube was formed. The limitations of the current method are also discussed.     

The effect of random point excitation on the vibration level of plates

When a mechanical structure is driven by stationary wide band random point forces, the resulting vibration depends upon the number, location, and joint statistical properties of the exciting forces. In this study, under the assumption of light damping, an approximate procedure for analyzing plates is briefly outlined. The effects of number, location and correlation of the force field on the vibration level are then investigated for various cases in which random point forces with band limited white noise are applied, and the optimal spacing between input forces that produces a relative minimum in the vibration response is predicted.     

Refinement procedure for the image alignment in high-resolution electron tomography

High-resolution electron tomography from a tilt series of transmission electron microscopy images requires an accurate image alignment procedure in order to maximise the resolution of the tomogram. This is the case in particular for ultra-high resolution where even very small misalignments between individual images can dramatically reduce the fidelity of the resultant reconstruction. A tomographic-reconstruction based and marker-free method is proposed, which uses an iterative optimisation of the tomogram resolution. The method utilises a search algorithm that maximises the contrast in tomogram sub-volumes. Unlike conventional cross-correlation analysis it provides the required correlation over a large tilt angle separation and guarantees a consistent alignment of images for the full range of object tilt angles. An assessment based on experimental reconstructions shows that the marker-free procedure is competitive to the reference of marker-based procedures at lower resolution and yields sub-pixel accuracy even for simulated high-resolution data.     

Packaging machine for “Mozartkugeln” controlled by a position recognition system

This paper explores some of the critical issues in the development of a picture position recognition system. The system uses an on-line correlation procedure. Its output is used to control a positioning and packaging machine, the design of which is described in some detail.     

车辆乘坐室内低频噪声声源识别研究

提出了一种用于车内低频噪声声源识别的理论分析方法。该方法摆脱了对试验的依赖，可用于车身结构低噪声优化设计（或修改）的迭代求解过程。分别采用所提方法和相关分析法，对某型国产轿车乘坐室内驾驶员右耳位置处的低频噪声主要来源进行识别，得出了一致的结论。     

Improvement in stage measuring technique of the ultrasonic sensor gauge

Bar check is the routine procedure in depth sounding to eliminate temperature influencing effect during the oceanographic surveying. This paper adopted the bar check concept prior to stream stage measuring on-site to improve the measuring accuracy and efficiency with popular ultrasonic sensor gauges. This study also propose both experimental dimensionless curves/corresponding equations and the relative profile of calibrating coefficients and ambient temperature of the specific ultrasonic sensor to accelerate the field calibrating process and for the bar check calibrating procedure being unavailable before the formal stage measuring. Then, field stage measuring data by a float-type gauge with which relative reliable measuring result being identified were compared with the data by an ultrasonic sensor gauge measuring simultaneously at the same location and obtained quite similar results. This advanced and improved stage measuring technique of ultrasonic sensor gauges without sonic conduit has been proved its practical validity in field stage accurate measuring throughout the on-site bar check procedure and introduced the process with dimensionless curves/formulas and relative correlation profile between calibrating coefficients and ambient temperature as well.     

Fractional frequency domain identification of NaCl–glucose solutions at physiological levels

Electrical impedance spectroscopy (EIS) has been used to characterize different biological materials. This article exposes a methodology oriented to estimate glucose levels of a solution based on a rational fractional parametric model of the impedance data. The methodology is applied over saline–glucose solutions at five physiological glucose levels, using three sensors and five repetitions for each glucose concentration and employed sensor. The results suggest that changes in the glucose concentration produce significant changes in the impedance that should be reflected in the parametric model. The modeling procedure shows that the poles and zeros of an integer model presents a degree of correlation. However, the correlation is clearly explicit employing fractional models where the mean location of the complex zeros is highly related to the glucose content in the sample.     

A general computer solution for radial and mixed flow turbomachine performance prediction

A general one dimensional performance prediction procedure applicable to both radial inflow turbines and centrifugal compressors is presented. By separating the fundamental one dimensional gas dynamic theory from the empiricism needed to extend the one dimensional analysis to a prediction procedure for a flow which is full three-dimensional, a single equation is developed to represent the flow in all types of ducts encountered in radial turbomachines. This separation of the fundamental gas dynamics from the application of empirical parameters gives the user a clear insight into the assumptions involved, and leads to a computer procedure which is constructed of a series of subroutines representing the empiricism needed for each duct. Consequently it is a relatively simple matter for the user to modify or replace any loss correlation in light of his own experience, and therefore, develop a computer prediction procedure which closely meets his own specific requirements.     

Effect of hob wear on the sounds emitted in the gear hobbing process

Increasing demand for precision and economy in gear manufacture necessitates control of the essential parameters in the hobbing process. Recognizing this necessity, research was undertaken to develop a hob wear detector. Using an empirical procedure, the acoustic signal emitted in hobbing was assessed with respect to its capacity to provide information about the extent of hobbing cutter wear. It was shown that signals from measurement of acoustic pressure in full bandwidths are unsuitable for the purpose. Frequency analysis of the acoustic signal enabled a third-octave frequency range with a centre frequency of 160 Hz to be singled out, wherein the acoustic signal level showed a close correlation with hob wear. The suitability of the signal is independent of most of the basic machine and process parameters and, for the purposes of hob wear detection, is reduced with higher values of module pitch of the hobbed gear     

基于PLS-LSSVM方法的湿法炼锌过程预测建模

在湿法炼锌过程中,沉铁工序具有流程长、化学反应耦合强和物理沉降过程复杂的特点.针对这一特点,提出基于PLS-LSSVM的预测建模方法.PLS能有效处理复杂冶金生产过程中的非线性、多输入和数据相关性等特性.同时,针对建模过程中LS-SVM两个重要参数的优化选择,提出免疫文化差分进化算法.仿真结果表明,本文提出的基于PLS-LSSVM的预测模型能取得较好的预测结果,为解决沉铁过程铁渣品位实时检测提供了一种有效可行的方法.     

Using a corrected least-squares procedure and accounting for structural parameters when analyzing the correlation between the impact strength of low-alloyed steels and their coercive force

The use of a corrected least-squares procedure that takes the error of impact-strength estimation into account, as well as several structure parameters, such as the equiaxial grain size number, Widmanstätten ferrite grain size number, and bainite percentage, allowed us to substantially improve the constraint equations between the impact strength and coercive force for a group of specimens. These specimens were sampled from no. 60 flange beams made of 09Г2 steel and exhibited no preliminary correlation between these parameters.     

Stereological methods in the analysis of neuronal parameters in the central nervous system*

The structure of the central nervous system (CNS) is briefly explained. It is compared with the electronic computer and the differences between the two are stated. The methods of measuring this structure and its function are reported. The surface of the cortex as well as the volume of different grey and white matters making up the brain can macroscopically be evaluated on serial slices with the aid of stereological procedures. There is an exponential correlation between volume of the cortex and volume of brain and body in mammals (Fig. 3). The density of neurons and the lengths of their processes can be examined by light microscopy. An improved procedure of counting neurons in the cortex is described. With regard to mammals it is interesting that the densities of neurons in larger brains are lower than in smaller ones. The correlation is negatively exponential. Man and primates have a higher density of cells than the rest of the mammals; their neurons, however, are small. This corresponds to a specialization that can be considered to represent a miniaturization of the neurons (Fig. 4). The topological analysis of dendritic trees is mentioned. The lengths, surfaces and volumes of processes of cells and the amount of synapses can be measured on electron micrographs. The principles and problems of stereology are described by an example of how to measure the myelinated fibres. Some results of the development of these fibres from birth on are reported upon (Fig. 6). In conclusion, some data of the probable dimensions of the human brain are given.     

Measurement technique for the on-line detection of fines in a fluidized bed

In many industrial applications knowledge of the particle size distribution in a fluidized bed and in particular knowledge of the proportion of fines, is extremely important in order to maintain good fluidization quality in the bed, and to prevent too many particles from leaving the cyclones in the gas stream. A common method of monitoring particle size in a laboratory situation is to take a sample of particles from the fluidized bed and use equipment such as a laser diffraction device to analyze the sample, which can be a cumbersome procedure. The objective of this study was to develop an online tool to monitor the proportion of fines in a fluidized bed. A novel online measurement technique for the detection of fines in fluidized beds was developed, which includes a correlation that relates the triboelectric signal to the proportion of fines in the bed.     

Analysis of variations in a multi-variate process using neural networks

In the area of quality control, several correlative quality characteristics may be considered simultaneously in a manufacturing process. In such a case, the Schewhart control charts neglect the influence of the correlation among these quality characteristics, leading to an incorrect judgment. Numerous methods have been proposed to control a process with multiple quality characteristics, however, most research emphasises only the variation of a process mean and devotes much less attention to the variation of a variance, relatively speaking. In this study, a neural network procedure is proposed for detecting variations in the variances, with the assumption that the mean value of the multiple quality characteristics of a process is under control. Two criteria, the average run length (ARL) and the average number of abnormal cases found, are used to evaluate the performance of the proposed procedure. The developed neural model is compared with the traditional |Σ| control method with regard to the aspect of detecting the variations in the variances in a process. The simulation results demonstrate the superiority of the proposed procedure in process control while multiple quality characteristics are simultaneously considered.     

Clustering and pair correlation function in atom probe tomography

The measurement of the composition of small clusters from 3D maps as provided by atom probe tomography or Monte-Carlo simulations is a very tricky issue. A method based on pair correlation functions was developed. The analytical expression of the pair correlation function as a function of the phase composition, the number density and the size of spherical particles for a two-phase mono-dispersed system has been established. A best-fit procedure applied to experimental pair correlation function is shown to be a simple, fast and elegant way to determine the concentration of clusters and that of the parent phase as well as the radius and the number density of clusters. Application to carbon-doped silicon demonstrates the validity of this approach. Results were found very close to those derived by other means. This method was also applied to boron clustering in implanted silicon where clusters are not visible in 3D images. The advantage of this approach over other methods such as erosion or cluster identification is discussed.