X-ray measurement of cellulose crystallite orientation in cotton fibers

The orientation of crystallites in a bundle of parallel cotton fibers was studied by x-ray diffraction. The intensity distributions of the 101 and 002 diffraction rings showed the distributions of (101) and (002) planes to be identical within the limits of accuracy. Therefore, the crystallites in the cotton fibers very likely had random orientation about their long axes. The orientation distribution of these axes was calculated by using the intensity distribution of the 002 diffraction ring. The cylindrically symmetrical density distribution J(β) thus obtained was multiplied by sin β to obtain the distribution of relative numbers of crystallites at given angles β to the long axis of the fiber. The average 〈β〉 was found to be in agreement with the value of 〈sin²β〉 measured from the 002 diffraction ring. The intensity distributions on the 101 and 002 diffraction rings showed small fluctuations. These fluctuations appeared much stronger in the J(β) and sin β J(β) distributions, indicating clear discontinuities in the pitch angle distribution.     

Effect of missing values in estimation of mean of auto-correlated measurement series

Sampling and uncertainty of sampling are important tasks, when industrial processes are monitored. Missing values and unequal sources can cause problems in almost all industrial fields. One major problem is that during weekends samples may not be collected. On the other hand a composite sample may be collected during weekend. These systematically occurring missing values (gaps) will have an effect on the uncertainties of the measurements. Another type of missing values is random missing values. These random gaps are caused, for example, by instrument failures. Pierre Gy's sampling theory includes tools to evaluate all error components that are involved in sampling of heterogeneous materials. Variograms, introduced by Gy's sampling theory, have been developed to estimate the uncertainty of auto-correlated process measurements. Variographic experiments are utilized for estimating the variance for different sample selection strategies. The different sample selection strategies are random sampling, stratified random sampling and systematic sampling. In this paper both systematic and random gaps were estimated by using simulations and real process data. These process data were taken from bark boilers of pulp and paper mills (combustion processes). When systematic gaps were examined a linear interpolation was utilized. Also cases introducing composite sampling were studied. Aims of this paper are: (1) how reliable the variogram is to estimate the process variogram calculated from data with systematic gaps, (2) how the uncertainty of missing gap can be estimated in reporting time-averages of auto-correlated time series measurements. The results show that when systematic gaps were filled by linear interpolation only minor changes in the values of variogram were observed. The differences between the variograms were constantly smallest with composite samples. While estimating the effect of random gaps, the results show that for the non-periodic processes the stratified random sampling strategy gives more reliable results than systematic sampling strategy. Therefore stratified random sampling should be used while estimating the uncertainty of random gaps in reporting time-averages of auto-correlated time series measurements.     

Ultrasound assisted method to increase soluble chemical oxygen demand (SCOD) of sewage sludge for digestion

The aim of this study was to clarify the possibilities to increase the amount of soluble chemical oxygen demand (SCOD) and methane production of sludge using ultrasound technologies with and without oxidising agents. The study was done using multivariate data analyses. The most important factors affected were discovered. Ultrasonically assisted disintegration increased clearly the amount of SCOD of sludge. Also more methane was produced from treated sludge in anaerobic batch assays compared to the sludge with no ultrasonic treatment. Multivariate data analysis showed that ultrasonic power, dry solid content of sludge (DS), sludge temperature and ultrasonic treatment time have the most significant effect on the disintegration. It was also observed that in the reactor studied energy efficiency with high ultrasound power together with short treatment time was higher than with low ultrasound power with long treatment time. When oxidising agents were used together with ultrasound no increase in SCOD was achieved compared the ultrasonic treatment alone and only a slight increase in total organic carbon of sludge was observed. However, no enhancement in methane production was observed when using oxidising agents together with ultrasound compared the ultrasonic treatment alone. Ultrasound propagation is an important factor in ultrasonic reactor scale up. Ultrasound efficiency rose linearly with input power in sludge at small distances from the transducer. Instead, ultrasound efficiency started even to decrease with input power at long distances from the transducer.     

Melt‐compounded nanocomposites of titanium dioxide atomic‐layer‐deposition‐coated polyamide and polystyrene powders

Polyamide and polystyrene particles were coated with titanium dioxide films by atomic layer deposition (ALD) and then melt‐compounded to form polymer nanocomposites. The rheological properties of the ALD‐created nanocomposite materials were characterized with a melt flow indexer, a melt flow spiral mould, and a rotational rheometer. The results suggest that the melt flow properties of polyamide nanocomposites were markedly better than those of pure polyamide and polystyrene nanocomposites. Such behavior was shown to originate in an uncontrollable decrease in the polyamide molecular weight, likely affected by a high thin‐film impurity content, as shown in gel permeation chromatography (GPC) and scanning electron microscope (SEM) equipped with an energy‐dispersive spectrometer. Transmission electron microscope image showed that a thin film grew on both studied polymer particles, and that subsequent melt‐compounding was successful, producing well dispersed ribbon‐like titanium dioxide with the titanium dioxide filler content ranging from 0.06 to 1.12 wt%. Even though we used nanofillers with a high aspect ratio, they had only a minor effect on the tensile and flexural properties of the polystyrene nanocomposites. The mechanical behavior of polyamide nanocomposites was more complex because of the molecular weight degradation. Our approach here to form polymeric nanocomposites is one way to tailor ceramic nanofillers and form homogenous polymer nanocomposites with minimal work‐related risks in handling powder form nanofillers. However, further research is needed to gauge the commercial potential of ALD‐created nanocomposite materials. Copyright © 2011 John Wiley & Sons, Ltd.     

Experimental aspects of ultrasonically enhanced cross-flow membrane filtration of industrial wastewater

Ultrasound based on-line cleaning for membrane filtration of industrial wastewater was studied. An ultrasonic transducer was assembled in the membrane module in order to get an efficient cleaning of membranes in fouling conditions. The focus of the studies was on the effects of the ultrasound propagation direction and frequency as well as the transmembrane pressure. The more open the membrane was the easier the membrane became plugged by wastewater colloids, when the ultrasound propagation direction was from the feed flow side of the membrane. If the membrane was tight enough, the ultrasound irradiated from the feed side of the membrane increased the flux significantly. However, in the circumstances studied, the power intensity needed during filtration was so high that the membranes eroded gradually at some spots of the membrane surface. It was discovered that the ultrasonic field produced by the used transducers was uneven in pressurised conditions. On the other hand, the ultrasound treatment at atmospheric pressure during an intermission pause in filtration turned out to be an efficient and, at the same time, a gentle method in membrane cleaning. The input power of 120 W (power intensity of 1.1 W/cm2) for a few seconds was sufficient for cleaning. The flux improvement was significant when using a frequency of 27 kHz but only minor when using 200 kHz.     

一类有理算术函数及其组合意义（英）

An arithmetical function f is said to be a rational arithmetical function of order (s,r) if there existcompletely multiplicative functions f₁,f₂,…,f_s and g₁,g₂,…,g_r such thatf=f₁*f₂*… *f_s*(g₁)^-1*(g₂)^-1*… *(g_r) -1 ,where * is the Dirichlet convolution. Recently, L.C. Hsu and Wang Jun studied combinatorial meanings of rational arithmetical functions of order (1,r) . We study these meanings in the setting of Narkiewicz's regular convolution.     

Not all Julia sets are quasi-self-similar

We show that there exist rational functions, whose Julia set fails to be quasi-self-similar.

     

Kinetics of the Oxidation of Monosaccharides with Acidic Bromate and N-Bromosuccinimide

Abstract

In earlier studies on the oxidation of monosaccharides, we measured the rates of the oxidation of three aldohexoses, two ketohexoses and three aldopentoses with V(V),¹ Ce(IV)²Cr(VI)³ and MII(VII).⁴We now report on the corresponding oxidations with bromate ion and N-bromosuccinimide (NBS) as oxidants. To our knowledge, only kinetic studies of oxidations of ribose with BrO₃-in aqueous H₂O₄ ⁵ and aldoses with NBS in 10% AcOH - H₂SO₄ ⁶ have been reported. Because oxidation of carbohydrates is subject to HSO₄- ion catalysis, HClO₄ was used, as in our earlier studies, in the present investigation to minimize the number of different catalyzing species.     

Filtering the histories of a partially observed marked point process

We consider a situation in which the evolution of an ‘underlying’ marked point process is of interest, but where this process is not directly observable. Instead, we assume that another marked point process, which is fully determined by the underlying process, can be observed. The problem is then the estimation, at any given time t, of the underlying development so far, given the corresponding observations. The solution, in the sense of a conditional distribution of the underlying pre-t history, is shown to satisfy a recursive filter formula. Sufficient conditions for the uniqueness of the solution are given. Two non-trivial examples are considered in detail.