scholarly journals Comparative evaluation of different kinetic models for batch cooking: A review

Holzforschung ◽  
2012 ◽  
Vol 66 (7) ◽  
pp. 791-799 ◽  
Author(s):  
Kaarlo Nieminen ◽  
Herbert Sixta
Keyword(s):  
Kinetic Models ◽  
Eucalyptus Globulus ◽  
Comparative Evaluation ◽  
Continuous Distribution ◽  
Kraft Cooking ◽  
Realistic Description ◽  
The Difference ◽  
Cooking Conditions

Abstract The purpose of this study was to review some of the existing models for delignification in kraft cooking. Data and results from earlier studies were utilized to evaluate the performance of the models of Gustafson (MG), Purdue (MP), Andersson (MA) and Bogren’s method “continuous distribution of reactivity” (MBcdr) in terms of their ability to give a realistic description for delignification of softwood and hardwood. The MG, MP and MBcdr were tested on lignin data obtained from cooks of Eucalyptus globulus. In this case, MP seemed to perform best, whereas the MBcdr failed in the range of low residual lignins. MA considers the lignin subunits with various reaction speeds, and this feature improves the performance in the case of low residual lignins and helps to reflect sudden changes in cooking conditions, but the difference to the ordinary MP is moderate.

scholarly journals Lipid and lignin composition of woods from different eucalypt species

Holzforschung ◽  
2007 ◽  
Vol 61 (2) ◽  
pp. 165-174 ◽  
Author(s):  
Jorge Rencoret ◽  
Ana Gutiérrez ◽  
José C. del Río
Keyword(s):  
Eucalyptus Globulus ◽  
Lignin Content ◽  
Kraft Pulping ◽  
Medium Length ◽  
Eucalypt Species ◽  
Kraft Cooking ◽  
Lignin Composition ◽  
G Ratio ◽  
Cooking Conditions

Abstract The lipid and lignin compositions of woods from the eucalypt species Eucalyptus globulus, E. nitens, E. maidenii, E. grandis, and E. dunnii have been characterized. The lipid composition was analyzed by GC and GC/MS using short- and medium-length high-temperature capillary columns, which allowed the detection of intact high-molecular-weight compounds. Similar lipid compositions were observed in all eucalypt woods, which were dominated by sitosterol, sitosterol esters and sitosteryl 3β-D-glucopyranoside. These substance classes are mainly responsible for pitch deposition during kraft pulping of eucalypt wood. However, some quantitative differences were found in the abundance of different lipid classes, with wood from E. globulus containing the lowest amounts of these pitch-forming compounds. The lignins of all eucalypt woods were analyzed in situ (without previous isolation) by pyrolysis-GC/MS. A predominance of syringyl (S) over guaiacyl (G) lignin units was observed and the S/G ratio was in the range from 2.7 to 4.1. E. globulus wood had the highest S/G ratio, a finding that, together with its low lignin content, explains its easy delignification under kraft cooking conditions.

Comparison of In-the-Ear and Over-the-Ear Hearing Aid Fittings

1986 ◽  
Vol 51 (4) ◽  
pp. 362-369 ◽  
Author(s):  
Donna M. Risberg ◽  
Robyn M. Cox
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Comparative Evaluation ◽  
Speech Intelligibility ◽  
Hearing Aid ◽  
Hearing Aid Fitting ◽  
The Difference ◽  
Functional Gain ◽  
The Relationship

A custom in-the-ear (ITE) hearing aid fitting was compared to two over-the-ear (OTE) hearing aid fittings for each of 9 subjects with mild to moderately severe hearing losses. Speech intelligibility via the three instruments was compared using the Speech Intelligibility Rating (SIR) test. The relationship between functional gain and coupler gain was compared for the ITE and the higher rated OTE instruments. The difference in input received at the microphone locations of the two types of hearing aids was measured for 10 different subjects and compared to the functional gain data. It was concluded that (a) for persons with mild to moderately severe hearing losses, appropriately adjusted custom ITE fittings typically yield speech intelligibility that is equal to the better OTE fitting identified in a comparative evaluation; and (b) gain prescriptions for ITE hearing aids should be adjusted to account for the high-frequency emphasis associated with in-the-concha microphone placement.

Prebleaching of eucalypt kraft pulp with OP stages: Effect of an acid pretreatment or chelation step

TAPPI Journal ◽  
2012 ◽  
Vol 11 (6) ◽  
pp. 31-38
Author(s):  
TATIANA M. PÓVOAS ◽  
DINA A.G. ANGÉLICO ◽  
ANA P.V. EGAS ◽  
PEDRO E.G. LOUREIRO ◽  
LICÍNIO M. GANDO-FERREIRA ◽  
...  
Keyword(s):  
Eucalyptus Globulus ◽  
Comparative Evaluation ◽  
Kraft Pulp ◽  
Kraft Pulps ◽  
Acid Pretreatment ◽  
High Brightness ◽  
Pulp Viscosity ◽  
Brightness Reversion

We conducted a comparative evaluation of different treatments for the bleaching of eucalypt kraft pulps beginning with OP stages. The treatments tested were (1) an acid chelation stage with DTPA (OQP sequence); (2) a hot acid stage (AOP sequence); and (3) a chelant addition into the alkaline oxygen stage ((OQ)P and A(OQ)P sequences). The latter strategy was also studied for environmental reasons, as it contributes to the closure of the filtrate cycle. The OQP sequence leads to the highest brightness gain and pulp viscosity and the lowest peroxide consumption caused by an efficient metals control. Considering that the low biodegradability of the chelant is a problem, the A(OQ)P sequence is an interesting option because it leads to reduced peroxide consumption (excluding OQP) while still reaching high brightness values and similar brightness reversion to OQP prebleaching, with only a viscosity loss of 160 dm3/kg. Therefore, a hot acid stage could be considered when a separate acid Q stage is absent in a prebleaching sequence of Eucalyptus globulus kraft pulps involving OP stages.

A Critique and Improvement of the CL Common Language Effect Size Statistics of McGraw and Wong

2000 ◽  
Vol 25 (2) ◽  
pp. 101-132 ◽  
Author(s):  
András Vargha ◽  
Harold D. Delaney
Keyword(s):  
Effect Size ◽  
Continuous Distribution ◽  
Interval Estimation ◽  
Continuous Variable ◽  
Common Language ◽  
Exact Methods ◽  
Normal Distributions ◽  
The Difference ◽  
Discrete Values ◽  
Two Populations

McGraw and Wong (1992) described an appealing index of effect size, called CL, which measures the difference between two populations in terms of the probability that a score sampled at random from the first population will be greater than a score sampled at random from the second. McGraw and Wong introduced this "common language effect size statistic" for normal distributions and then proposed an approximate estimation for any continuous distribution. In addition, they generalized CL to the n-group case, the correlated samples case, and the discrete values case. In the current paper a different generalization of CL, called the A measure of stochastic superiority, is proposed, which may be directly applied for any discrete or continuous variable that is at least ordinally scaled. Exact methods for point and interval estimation as well as the significance tests of the A = .5 hypothesis are provided. New generalizations ofCL are provided for the multi-group and correlated samples cases.

scholarly journals Törnqvist Formula for Сalculating a Consumer Price Index in Russia: Theory and Practice

2020 ◽  
Vol 27 (5) ◽  
pp. 87-94
Author(s):  
М. A. Kozlova
Keyword(s):  
Price Index ◽  
Empirical Studies ◽  
Consumer Price Index ◽  
Theory And Practice ◽  
Consumer Market ◽  
Country Level ◽  
Consumer Prices ◽  
Realistic Description ◽  
The Difference ◽  
Main Consumer

The article reflects the author’s position on the adjustment of the so-called substitution bias, which affects the value of the consumer price index, currently calculated using the Laspeyres formula. The author proposes a solution to the problem of the adequacy of statistical measurements of the dynamics of consumer prices in the case when, as a result of changing cost of the consumer basket, a buyer replaces a relatively expensive product with a relatively cheaper one. This solution is based on the existing index construction methodology (axiomatic, economic and stochastic approaches). The article substantiates the use of the Törnqvist formula, which has better properties in comparison with other formulae used in the construction of superlative indices. The authors calculated the Törnqvist price index for Russia based on Rosstat methodology and data using country-level quarterly group price indices and shares of consumer spending. To evaluate the results of empirical testing Laspeyres price index was compiled using the same quarterly data as the Törnqvist index. The values of the Törnqvist price index in most cases are less than the price dynamics obtained according to the Laspeyres formula. This conclusion is proved both theoretically and empirically, and it is confirmed for Russia as well. However, due to the non-observance of the conditions of smooth trends in consumer prices, the difference between the values of the Törnqvist and Laspeyres indices is significantly larger in certain quarters than that presented in empirical studies in other countries. Consumer price index, calculated using the Törnqvist formula, in the system of indicators of price statistics in Russia can be defined as an indicator that specifies the main consumer price index. Calculation of its value is necessary for a more realistic description of the processes taking place in the consumer market.

scholarly journals Two Useful Discrete Distributions to Model Overdispersed Count Data

2020 ◽  
Vol 43 (1) ◽  
pp. 21-48
Author(s):  
Josmar Mazucheli ◽  
Wesley Bertoli ◽  
Ricardo Puziol Oliveira
Keyword(s):  
Infinite Series ◽  
Count Data ◽  
Survival Function ◽  
Continuous Distribution ◽  
Discrete Distributions ◽  
Mathematical Expressions ◽  
Probability Mass ◽  
The Difference ◽  
Discrete Analogues ◽  
Mass Functions

The methods to obtain discrete analogues of continuous distributions have been widely considered in recent years. In general, the discretization process provides probability mass functions that can be competitive with the traditional model used in the analysis of count data, the Poisson distribution. The discretization procedure also avoids the use of continuous distribution in the analysis of strictly discrete data. In this paper, we seek to introduce two discrete analogues for the Shanker distribution using the method of the infinite series and the method based on the survival function as alternatives to model overdispersed datasets. Despite the difference between discretization methods, the resulting distributions are interchangeable. However, the distribution generated by the method of infinite series method has simpler mathematical expressions for the shape, the generating functions and the central moments. The maximum likelihood theory is considered for estimation and asymptotic inference concerns. A simulation study is carried out in order to evaluate some frequentist properties of the developed methodology. The usefulness of the proposed models is evaluated using real datasets provided by the literature.

scholarly journals Utilization of Insecticide Treated Bed Nets (ITNs) among Caregivers of Children under Five Years in the Ho Municipality

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Kennedy Diema Konlan ◽  
Milipaak Japiong ◽  
Kennedy Dodam Konlan ◽  
Agani Afaya ◽  
Solomon Mohammed Salia ◽  
...  
Keyword(s):  
Continuous Distribution ◽  
Cross Sectional Study ◽  
Bed Nets ◽  
Cross Sectional ◽  
Effective Measure ◽  
Children Under Five ◽  
Under Five ◽  
The Difference ◽  
Multistage Sampling ◽  
Insecticide Treated Bed Nets

Background. In Ghana, attempts to control malaria through antimalarial medications are currently threatened by the emergence and spread of drug resistant malaria parasites. This, together with the increasing incidence of malaria, has heightened the need for a more effective method of controlling the spread. The use of Insecticide Treated Bed Net (ITN) has been recognised as an effective measure in the prevention of malaria. Objective/Purpose. In this study, we examined the utilisation of ITN among caregivers of children under five years in Ho municipality of Ghana. Methods. This descriptive cross-sectional study recruited 283 household representatives through a multistage sampling method. A questionnaire was used to collect the data and was analyzed using STATA version 14. Descriptive and inferential statistics were adopted in presenting the data. Results. Ownership of ITN was higher (80.7%) than its utilisation (41.7%). The age of caregiver was strongly associated with the utilisation of ITN (AOR=2.00, 95% CI=0.00, 0.02, p<0.001) among children less than five years. Caregivers aged 26-35 were 49% times less likely to use an ITN as compared to those aged between 17 and 25 and the difference was statistically significant. Conclusion. In order to ensure a high ITN coverage and utilisation, there is the need for continuous distribution of ITNs to households. Households should be sensitized to use the nets to prevent the continuous spread of malaria.

Biorefinery in a pulp mill: simultaneous production of cellulosic fibers from Eucalyptus globulus by soda-anthraquinone cooking and surface-active agents

Holzforschung ◽  
2013 ◽  
Vol 67 (5) ◽  
pp. 481-488 ◽  
Author(s):  
Marion Sanglard ◽  
Christine Chirat ◽  
Bevan Jarman ◽  
Dominique Lachenal
Keyword(s):  
Eucalyptus Globulus ◽  
Pulp Mill ◽  
Wood Chips ◽  
Oxygen Delignification ◽  
Cellulosic Fibers ◽  
Surface Active Agents ◽  
Cooking Temperature ◽  
Kraft Cooking ◽  
Surface Active ◽  
The Impact

Abstract Industrial Eucalyptus globulus wood chips were submitted to different autohydrolysis conditions followed by kraft cooking and soda-anthraquinone cooking. The autohydrolyzed wood chips were much easier to delignify than the control wood chips. Soda-anthraquinone cooking could be performed at a cooking temperature that was 20°C lower than that for the kraft cooking on control wood chips. Furthermore, the active alkali could be reduced. The resulting unbleached pulps reacted as well to oxygen delignification as the control pulps and could be further bleached to 90% ISO brightness with a D(EP)D sequence. The autohydrolysis liquors were investigated for their suitability as a source for the synthesis of alkylpolyxylosides (APX). These surface-active agents are synthesized through the reaction between the saccharides of the autohydrolysates and a fatty alcohol, with the former being the hydrophilic and the latter being the hydrophobic part of the molecule. The impact of the substances detected in autohydrolysates on the APX synthesis was studied. It was demonstrated that lignin dissolved during autohydrolysis should at least partially be removed before the production of APX.

scholarly journals Lipophilic Extractives from Eucalyptus globulus Pulp during Kraft Cooking Followed by TCF and ECF Bleaching

Holzforschung ◽  
2001 ◽  
Vol 55 (3) ◽  
pp. 260-264 ◽  
Author(s):  
A. Gutiérrez ◽  
J. Romero ◽  
J.C. del Río
Keyword(s):  
Gas Chromatography ◽  
Chlorine Dioxide ◽  
Eucalyptus Globulus ◽  
Gas Chromatography Mass Spectrometry ◽  
Chemical Analyses ◽  
Wood Extractives ◽  
Elemental Chlorine ◽  
Kraft Cooking ◽  
Ecf Bleaching ◽  
Paper Pulps

SummaryThe chemical composition of lipophilic extractives in paper pulps fromEucalyptus globuluswood during kraft cooking followed by TCF (“totally chlorine free”) and ECF (“elemental chlorine free”) bleaching sequences has been determined by gas chromatography and gas chromatography-mass spectrometry. The chemical analyses revealed that the composition of the lipophilic extractives in pulp after kraft cooking and TCF bleaching with hydrogen peroxide was similar to that ofE. globuluswood extractives, sitosterol and sitosterol esters being the predominant compounds. In contrast, the presence of these compounds was almost negligible in pulp after ECF bleaching with chlorine dioxide and only the saturated sterol stigmastanol, in both free and esterified forms, survived the bleaching.

Sign in / Sign up

Export Citation Format

Share Document