Academic literature on the topic 'Minimum meal frequency'
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Journal articles on the topic "Minimum meal frequency"
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Wagris, Mohammed, Anwar Seid, Molla Kahssay, and Osman Ahmed. "Minimum Meal Frequency Practice and Its Associated Factors among Children Aged 6–23 Months in Amibara District, North East Ethiopia." Journal of Environmental and Public Health 2019 (December 18, 2019): 1–7. http://dx.doi.org/10.1155/2019/8240864.
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Background. Minimum meal frequency, a proxy indicator for a child’s energy requirements, examines the number of times children received foods other than breast milk. Without adequate diversity and meal frequency, infants and young children are vulnerable to malnutrition, especially stunting and micronutrient deficiencies, and increased morbidity and mortality. In Ethiopia, only 45% of children had fed with an age-appropriate minimum meal frequency. Objective. The study was aimed to assess the minimal meal frequency practice, and its associated factors among children aged 6–23 months in Amibara district, North East Ethiopia. Methods. A community-based cross-sectional study was conducted from May 07–May 23, 2018. Systematic random sampling technique was applied to select 367 children aged 6–23 months. The univariable and multivariable binary logistic regression analyses model was used to identify potential predictors of meeting minimum meal frequency. All variables with P values <0.25 in the univariable analysis were taken to multivariable analysis, and variables at P values <0.05 were considered as statistically significant. Results. The study revealed a prevalence of minimum meal frequency 69.2% (95% CI: 0.64–0.74). Timely initiation of breastfeeding (AOR = 2.2, 95% CI (1.17, 4.18)), current breastfeeding status (AOR = 7.5, 95% CI (3.95, 14.4)), meeting minimum dietary diversity (AOR = 3.7, 95% CI (1.85, 7.44)), and household hunger scale (AOR = 5.3, 95% CI (1.5, 12.5)) were some of the significant predictors to achieve minimum meal frequency. Conclusion. The prevalence of minimum meal frequency practice is low in the study area. Current breastfeeding status, timely initiation of breastfeeding, no/little household hunger scale, and meeting minimum dietary diversity were found as significant predictors for minimum meal frequency practice. Mothers having children aged 6–23 months should be aware and practice appropriate infant and young child feeding practices including timely initiation of breastfeeding, breastfeeding till the child celebrate his/her second birthday, recommended meal frequency, and dietary diversity practice. In addition, households should be assessed and strengthened for food security.
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Jain, Ayushi, Muneer Kalliyil, and Satish Agnihotri. "Minimum Diet Diversity and Minimum Meal Frequency – Do They Matter Equally? Understanding IYCF Practices in India." Current Developments in Nutrition 4, Supplement_2 (May 29, 2020): 1012. http://dx.doi.org/10.1093/cdn/nzaa054_084.
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Abstract Objectives Infant and Young Child Feeding practices, mainly, complementary feeding in children between 6 months and two years of age, is found to be sub-optimal and emerge as the weakest link in improving child nutrition outcomes in India. Minimum Acceptable Diet (MAD), comprising of two sub-indicator – Minimum Dietary Diversity (MDD) and Minimum Meal Frequency (MMF), serves as an essential indicator to understand the diet adequacy pattern in children. The objective of this study was thus to investigate the role of MDD-MMF dyad in influencing the nutritional outcomes in children and its pattern across regions in India. Methods Data was obtained from the National Family Health Survey – 4 (NFHS-4) from the DHS Program website. The prevalence of MMF and MDD was calculated for 640 districts in India. The MMF and MDD were classified into three categories - high, medium and low based on equal percentile distribution of their prevalence range. Districts with high MMF and high MDD formed one cohort. Similarly, eight other cohorts were created based on their performance on MMF and MDD indicator. The prevalence of Stunting (St), Wasting (Wa) and Underweight (Uw) in children between 6 months and two years of age was then calculated for each of the nine cohorts. The districts were also mapped based on their cohort category to study the variation across regions in India. Results All three anthropometric indicators – stunting, wasting and underweight showed significant decline moving across low MMF- low MDD cohort (40% St; 26.2% Wa; 37.1% Uw) to medium MMF – medium MDD cohort (38.6% St; 23.8% Wa; 35.4% Uw) to high MMF – high MDD cohort (29% St; 15.5% Wa; 19.2% Uw). Second, the importance of minimum dietary diversity in improving nutritional outcomes was revealed, as opposed to minimum meal frequency, which shows improvement only when it reaches a certain threshold. Third, mapping revealed sharp differences across various regions in MMF-MDD pattern, especially in the states like Odisha, Assam and Andhra Pradesh. States in the central region performed poorly on complementary feeding indicators, specifically diet diversity. Conclusions The study highlights the importance of optimal complementary feeding practices in improving nutrition outcomes and the need to consider the regional heterogeneities while promoting IYCF practices in India. Funding Sources None.
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Scarpa, Giulia, Lea Berrang-Ford, Maria Galazoula, Paul Kakwangire, Didacus B. Namanya, Florence Tushemerirwe, Laura Ahumuza, and Janet E. Cade. "Identifying Predictors for Minimum Dietary Diversity and Minimum Meal Frequency in Children Aged 6–23 Months in Uganda." Nutrients 14, no. 24 (December 7, 2022): 5208. http://dx.doi.org/10.3390/nu14245208.
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Adequate complementary foods contribute to good health and growth in young children. However, many countries are still off-track in achieving critical complementary feeding indicators, such as minimum meal frequency (MMF), minimum dietary diversity (MDD) and minimum acceptable diet (MAD). In this study, we used the 2016 Ugandan Demographic Health Survey (UDHS) data to assess child feeding practices in young children aged 6–23 months. We assess and describe complementary feeding indicators (MMF, MDD and MAD) for Uganda, considering geographic variation. We construct multivariable logistic regression models—stratified by age—to evaluate four theorized predictors of MMF and MDD: health status, vaccination status, household wealth and female empowerment. Our findings show an improvement of complementary feeding practice indicators in Uganda compared to the past, although the MAD threshold was reached by only 22% of children. Children who did not achieve 1 or more complementary feeding indicators are primarily based in the northern regions of Uganda. Cereals and roots were the foods most consumed daily by young children (80%), while eggs were rarely eaten. Consistent with our hypotheses, we found that health status, vaccination status and wealth were significantly positively associated with MDD and MMF, while female empowerment was not. Improving nutrition in infant and young children is a priority. Urgent nutritional policies and acceptable interventions are needed to guarantee nutritious and age-appropriate complementary foods to each Ugandan child in the first years of life.
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Manzione, Lauren, Heidi Kriser, Emily Gamboa, Curtis Hanson, Generose Mulokozi, Osiah Mwaipape, Taylor Hoj, et al. "Maternal Employment Status and Minimum Meal Frequency in Children 6-23 Months in Tanzania." International Journal of Environmental Research and Public Health 16, no. 7 (March 29, 2019): 1137. http://dx.doi.org/10.3390/ijerph16071137.
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As women in developing world settings gain access to formal work sectors, it is important to understand how such changes might influence child nutrition. The purpose of this paper is to examine the relationship between maternal employment status and minimum meal frequency (MMF) among children in Tanzania. Interviews were conducted with 5000 mothers of children ages 0–23 months. The questionnaire used in these interviews was developed by adopting questions from Tanzania’s latest Demographic and Health Survey (2015–2016) where possible and creating additional questions needed for programmatic baseline measurements. MMF was used as proxy for child nutrition. Logistic regression analyses were used to identify associations between employment status and parenting practices of Tanzanian mothers and MMF of their children. After adjusting for confounders, informal maternal employment [OR = 0.58], lack of financial autonomy [OR = 0.57] and bringing the child with them when working away from home [OR = 0.59] were negatively associated with meeting MMF. Payment in cash [OR = 1.89], carrying food for the child [OR = 1.34] and leaving food at home for the child [OR = 2.52] were positively associated with meeting MMF. Informal maternal employment was found to be negatively associated with meeting MMF among Tanzanian children. However, behaviors such as bringing or leaving prepared food, fiscal autonomy and payment in cash showed significant positive associations. These findings could help direct future programs to reduce child stunting.
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Thobias, Irmawati Apriany, and Kusharisupeni Djokosujono. "KERAGAMAN MAKAN MINIMUM SEBAGAI FAKTOR DOMINAN STUNTING PADA ANAK USIA 6-23 BULAN DI KABUPATEN KUPANG." JURNAL KESMAS DAN GIZI (JKG) 3, no. 2 (April 30, 2021): 136–43. http://dx.doi.org/10.35451/jkg.v3i2.592.
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Background: Stunting in children is one of the things that most significantly hinders human development, which globally affects around 162 million children under 5 years (WHO, 2017). Kupang Regency is one of the contributors to the stunting rate with a prevalence of 46.2% in 2013 and increasing in 2019 to 50.3% (SSGBI, 2019).
Objectives: This study aims to determine the factors most associated with the incidence of stunting in children 6 -23 months in Kupang Regency.
Methods: This study used secondary data from the results of the 2019 YASATU NGO survey with the simple random sampling method, with a sample of 166 children aged 6-23 months. The variables analyzed consisted of the dependent variable stunting, the independent variables: maternal age and education, age and sex of the child, breastfeeding status, minimum dietary diversity, minimum meal frequency, and minimum acceptable diet.
Results: The bivariate analysis showed that there hadn’t a relationship between maternal age, maternal education, child age, child sex, breasfeeding status on the incidence of stunting. Meanwhile, there was a significant relationship between minimum dietary diversity (MDD), minimum meal frequency (MMF), minimum acceptable diet (MAD) on the incidence of stunting. The final result of multivariate analysis showed that minimum dietary diversity had the greatest Odds Ratio (OR=12,341; CI 95%=3,118-48,841). It was controlled by breastfeeding status, minimum meal frequency and minimum accpetable diet.
Conclusion: Minimum dietary diversity is a dominant factor of stunting in children aged 6-23 months in Kupang Regency. Children who did not meet MDD have 12,3 times higher risk of stunting than those who meet MDD.
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Macharia, T. N., S. Ochola, M. K. Mutua, and E. W. Kimani-Murage. "Association between household food security and infant feeding practices in urban informal settlements in Nairobi, Kenya." Journal of Developmental Origins of Health and Disease 9, no. 1 (January 18, 2018): 20–29. http://dx.doi.org/10.1017/s2040174417001064.
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Studies in urban informal settlements show widespread inappropriate infant and young child feeding (IYCF) practices and high rates of food insecurity. This study assessed the association between household food security and IYCF practices in two urban informal settlements in Nairobi, Kenya. The study adopted a longitudinal design that involved a census sample of 1110 children less than 12 months of age and their mothers aged between 12 and 49 years. A questionnaire was used to collect information on: IYCF practices and household food security. Logistic regression was used to determine the association between food insecurity and IYFC practices. The findings showed high household food insecurity; only 19.5% of the households were food secure based on Household Insecurity Access Score. Infant feeding practices were inappropriate: 76% attained minimum meal frequency; 41% of the children attained a minimum dietary diversity; and 27% attained minimum acceptable diet. With the exception of the minimum meal frequency, infants living in food secure households were significantly more likely to achieve appropriate infant feeding practices than those in food insecure households: minimum meal frequency (adjusted odds ratio (AOR)=1.26,P=0.530); minimum dietary diversity (AOR=1.84,P=0.046) and minimum acceptable diet (AOR=2.35,P=0.008). The study adds to the existing body of knowledge by demonstrating an association between household food security and infant feeding practices in low-income settings. The findings imply that interventions aimed at improving infant feeding practices and ultimately nutritional status need to also focus on improving household food security.
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Ng, Charmaine S., Michael J. Dibley, and Kingsley E. Agho. "Complementary feeding indicators and determinants of poor feeding practices in Indonesia: a secondary analysis of 2007 Demographic and Health Survey data." Public Health Nutrition 15, no. 5 (October 11, 2011): 827–39. http://dx.doi.org/10.1017/s1368980011002485.
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AbstractObjectiveThe present study aimed to assess complementary feeding practices and identify the potential risk factors associated with inappropriate complementary feeding in Indonesia for a nationally representative sample of births from 2004 to 2007.DesignThe data source for the analysis was the 2007 Indonesia Demographic and Health Survey. Multiple logistic regression was performed to analyse the factors associated with complementary feeding, using individual-, household- and community-level determinants.SettingIndonesia.SubjectsChildren (n 4604) aged 6–23 months.ResultsMultivariate analysis revealed that infants from poor households were significantly less likely to be introduced to complementary feeding (adjusted odds ratio, AOR = 4·32; 95 % CI 1·46, 12·80) and meet the minimum dietary diversity (AOR = 1·76; 95 % CI 1·16, 2·68). Mother's education (AOR for no education in dietary diversity = 1·92; 95 % CI 1·09, 3·38; AOR for no education in meal frequency = 2·03; 95 % CI 1·13, 3·64; AOR for no education in acceptable diet = 3·84; 95 % CI 2·07, 7·12), residence and decreased age of the infant were negatively associated with minimum dietary diversity, minimum meal frequency and an acceptable diet. Infants aged 6–11 months were also significantly less likely to meet minimum dietary diversity (AOR = 6·36; 95 % CI 4·73, 8·56), minimum meal frequency (AOR = 2·30; 95 % CI 1·79, 2·96) and minimum acceptable diet (AOR = 2·27; 95 % CI 1·67, 3·09). All geographical regions compared with Sumatra were more likely to give the recommended meal frequency and an acceptable diet to breast-fed children.ConclusionsPublic health interventions to improve complementary feeding should address individual-, household- and community-level factors which significantly influence the introduction of complementary feeding. Complementary feeding intervention programmes in Indonesia should ensure that restraints on families with low socio-economic status are addressed. Infants aged 6–11 months and mothers with low education levels may also need special focus. Promotion strategies should also target the health-care delivery system and the media.
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Kemboi, Sharon, Dorothy Mungiria-Mituki, Rose Ramkat, Celine Termote, Namukolo Covic, and Maureen Jepkorir Cheserek. "Variation in the Factors Associated With Diet Quality of Children Aged 6 to 23 Months in Low and High Agroecological Zones of Rongai Subcounty, Kenya." Food and Nutrition Bulletin 41, no. 2 (June 2020): 186–99. http://dx.doi.org/10.1177/0379572120912875.
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Background: Adequate quality complementary diets and appropriate feeding practices are important for proper growth and development of young children. Objective: To assess factors associated with diet diversity, meal frequency, and acceptable diet of children aged 6 to 23 months in two agroecological zones of Rongai subcounty, Kenya. Methods: A cross-sectional study was conducted among 384 mothers/caregivers with children aged 6 to 23 months. A structured questionnaire was used to assess sociodemographic characteristics and child feeding practices. Diet diversity, meal frequency, and acceptable diet were derived from a 24-hour recall of child’s food intake. Factors associated with diet quality were determined using binary logistic regression. Results: Mean child diet diversity score was 3.54 ± 1.0 of 7 food groups, with 56.8% of the children achieving minimum dietary diversity. A majority of the children (81.8%) received minimum meal frequency (MMF), with significant ( P < .05) difference between low (91.1%) and high (75.2%) agricultural potential areas. Children who received minimum acceptable diet (MAD) were only 34.1%. Mother/caregiver education level positively ( P < .05) associated with minimum diet diversity in low potential area (adjusted odds ratio [AOR] = 3.79, 95% CI: 1.47-9.75) and with MAD in high potential area (AOR = 1.87, 95% CI: 1.01-3.46). Other factors associated with MDD, MMF, and MAD included household income and slow feeding in low potential area, and child gender and active feeding in high potential area. Conclusion: There is a variation in factors associated with diet quality and child feeding practices in different agroecological zones. Therefore, nutrition education and behavior change communication interventions aimed at improving child nutrition should be context-specific.
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Morseth, Marianne S., Liv Elin Torheim, Mekdes K. Gebremariam, Ram K. Chandyo, Manjeswori Ulak, Sanjaya K. Shrestha, Binob Shrestha, and Sigrun Henjum. "Tracking of infant and young child feeding practices among 9- to 24-month-old children in Nepal: the MAL-ED Birth Cohort Study." Public Health Nutrition 21, no. 2 (October 17, 2017): 355–64. http://dx.doi.org/10.1017/s1368980017002294.
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AbstractObjectiveThe present study aimed to assess infant and young child feeding (IYCF) practices and the tracking of dietary diversity score (DDS), intakes of Fe- and vitamin A-rich foods and meal frequency in a peri-urban area in Nepal. Furthermore, to explore whether sociodemographic factors were associated with tracking patterns of these IYCF practices.DesignLongitudinal study. Monthly food intake was measured by 24 h recall. Four time slots were used (9–12, 13–16, 17–20 and 21–24 months). Tracking of IYCF practices was investigated using generalized estimating equations (GEE) models and Cohen’s weighted kappa. Multinominal logistic regression was used to identify determinants for tracking of the IYCF practices.SettingBhaktapur municipality, Nepal.SubjectsChildren (n 229) aged 9–24 months, randomly selected.ResultsPrevalence of minimum meal frequency was higher than for minimum dietary diversity at all time slots. Tracking based on absolute measures (GEE models) was moderate for DDS (0·48) and meal frequency (0·53), and low for intakes of Fe- (0·23) and vitamin A-rich (0·35) foods. Tracking based on rank measured was moderate for DDS and meal frequency, and fair for Fe- and vitamin A-rich foods. Low socio-economic status significantly increased the odds (OR; 95 % CI) of tracking of low v. high DDS (3·31; 1·44, 7·60) and meal frequency (3·46; 1·54, 7·76).ConclusionsLow tracking for intakes of Fe- and vitamin A-rich foods implies that interventions to improve these IYCF practices must address underlying causes for irregular intake to have sustainable effects.
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Mulenga, Haswel, AM Mwangwela, J. Kampanje-Phiri, and B. Mtimuni. "Influence of gendered roles on legume utilization and improved child dietary intake in Malawi." African Journal of Food, Agriculture, Nutrition and Development 21, no. 03 (May 5, 2021): 17764–86. http://dx.doi.org/10.18697/ajfand.98.18205.
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The relationship between gender roles, legume production, utilization and child feeding practices in rural smallholder households of Dedza and Ntcheu districts in Malawi was investigated and analyzed. A cross-sectional research study was conducted with legume farming households with children aged 6-23 months who were part of the Africa RISING ‘mother trial’ or ‘baby trials’ for two farming seasons (2014/2015 to 2015/2016). Africa RISING project encourages smallholder farmers to grow legumes namely,groundnut (Arachis hypogaea),cowpea (Vigna unguiculata), pigeon pea (Cajanus cajan)and soya bean (Glycin max) as one way of improving the wellbeing of smallholder farmers. The key objective of the research was to assess the influence of gender roles,legume production, utilization and infant and young child dietary intake.In total, 291 households with children 6-23 months were targeted. Eight focus group discussions (FDGs) for in-depth qualitative data were conducted. Two 24-hour dietary recalls and food frequency questionnaires were used to collect data on infant and young child feeding (IYCF)practices. Data collected were extracted, arranged, recorded and analyzed by using SPSS version 21. About 18% of children aged 6-23 months received a minimum dietary diversity(the consumption of four or more food groups from the seven food groups), 2.5% received a minimum acceptable diet(indicator measures both the minimum feeding frequency and minimum dietary diversity, as appropriate for various age groups)and 37.5% of children received a minimum meal frequency(frequency of receiving solid, semi-solid, or soft foods at the minimum numbers of two and three times for children aged 6–8 months, and 9–23 months,respectively). Control on use of income by women had a positive and significant association with minimum dietary diversity (P<0.05), minimum meal frequency (P<0.05) and minimum acceptable diets (P<0.05) among children of both sexes. Children aged 6-23 months from households where women were actively involved in partial processing and budgeting of legumes met minimum dietary diversity than children from non-participating households. Women farmers were more knowledgeable about legumes; played an important role in seed selection, storage and processing; however, the findings signal an opportunity to increase women’s income by involving them in market information. Increasing legume production at household level does not mean increasing the nutritional status among children (6-23 months). Several factors related to gender roles, markets accessibility and legume utilization have an effect on infantand young child feeding practices.
Dissertations / Theses on the topic "Minimum meal frequency"
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Challakere, Nagaravind. "Carrier Frequency Offset Estimation for Orthogonal Frequency Division Multiplexing." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1423.
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This thesis presents a novel method to solve the problem of estimating the carrier frequency set in an Orthogonal Frequency Division Multiplexing (OFDM) system. The approach is based on the minimization of the probability of symbol error. Hence, this approach is called the Minimum Symbol Error Rate (MSER) approach. An existing approach based on Maximum Likelihood (ML) is chosen to benchmark the performance of the MSER-based algorithm. The MSER approach is computationally intensive. The thesis evaluates the approximations that can be made to the MSER-based objective function to make the computation tractable. A modified gradient function based on the MSER objective is developed which provides better performance characteristics than the ML-based estimator. The estimates produced by the MSER approach exhibit lower Mean Squared Error compared to the ML benchmark. The performance of MSER-based estimator is simulated with Quaternary Phase Shift Keying (QPSK) symbols, but the algorithm presented is applicable to all complex symbol constellations.
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Kahaei, Mohammad Hossein. "Performance analysis of adaptive lattice filters for FM signals and alpha-stable processes." Thesis, Queensland University of Technology, 1998. https://eprints.qut.edu.au/36044/7/36044_Digitised_Thesis.pdf.
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The performance of an adaptive filter may be studied through the behaviour
of the optimal and adaptive coefficients in a given environment. This thesis
investigates the performance of finite impulse response adaptive lattice filters for
two classes of input signals: (a) frequency modulated signals with polynomial
phases of order p in complex Gaussian white noise (as nonstationary signals),
and (b) the impulsive autoregressive processes with alpha-stable distributions (as
non-Gaussian signals).
Initially, an overview is given for linear prediction and adaptive filtering. The
convergence and tracking properties of the stochastic gradient algorithms are discussed
for stationary and nonstationary input signals. It is explained that the
stochastic gradient lattice algorithm has many advantages over the least-mean
square algorithm. Some of these advantages are having a modular structure,
easy-guaranteed stability, less sensitivity to the eigenvalue spread of the input autocorrelation
matrix, and easy quantization of filter coefficients (normally called
reflection coefficients).
We then characterize the performance of the stochastic gradient lattice algorithm
for the frequency modulated signals through the optimal and adaptive
lattice reflection coefficients. This is a difficult task due to the nonlinear dependence
of the adaptive reflection coefficients on the preceding stages and the input
signal. To ease the derivations, we assume that reflection coefficients of each
stage are independent of the inputs to that stage. Then the optimal lattice filter
is derived for the frequency modulated signals. This is performed by computing
the optimal values of residual errors, reflection coefficients, and recovery errors.
Next, we show the tracking behaviour of adaptive reflection coefficients for
frequency modulated signals. This is carried out by computing the tracking model
of these coefficients for the stochastic gradient lattice algorithm in average. The
second-order convergence of the adaptive coefficients is investigated by modeling
the theoretical asymptotic variance of the gradient noise at each stage. The
accuracy of the analytical results is verified by computer simulations.
Using the previous analytical results, we show a new property, the polynomial
order reducing property of adaptive lattice filters. This property may be used to
reduce the order of the polynomial phase of input frequency modulated signals.
Considering two examples, we show how this property may be used in processing
frequency modulated signals. In the first example, a detection procedure in carried
out on a frequency modulated signal with a second-order polynomial phase
in complex Gaussian white noise. We showed that using this technique a better
probability of detection is obtained for the reduced-order phase signals compared
to that of the traditional energy detector. Also, it is empirically shown that
the distribution of the gradient noise in the first adaptive reflection coefficients
approximates the Gaussian law. In the second example, the instantaneous frequency
of the same observed signal is estimated. We show that by using this
technique a lower mean square error is achieved for the estimated frequencies at
high signal-to-noise ratios in comparison to that of the adaptive line enhancer.
The performance of adaptive lattice filters is then investigated for the second
type of input signals, i.e., impulsive autoregressive processes with alpha-stable
distributions . The concept of alpha-stable distributions is first introduced. We
discuss that the stochastic gradient algorithm which performs desirable results
for finite variance input signals (like frequency modulated signals in noise) does
not perform a fast convergence for infinite variance stable processes (due to using
the minimum mean-square error criterion). To deal with such problems, the
concept of minimum dispersion criterion, fractional lower order moments, and
recently-developed algorithms for stable processes are introduced.
We then study the possibility of using the lattice structure for impulsive stable
processes. Accordingly, two new algorithms including the least-mean P-norm
lattice algorithm and its normalized version are proposed for lattice filters based
on the fractional lower order moments. Simulation results show that using the
proposed algorithms, faster convergence speeds are achieved for parameters estimation
of autoregressive stable processes with low to moderate degrees of impulsiveness
in comparison to many other algorithms. Also, we discuss the effect of
impulsiveness of stable processes on generating some misalignment between the
estimated parameters and the true values. Due to the infinite variance of stable
processes, the performance of the proposed algorithms is only investigated using
extensive computer simulations.
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Nourbakhsh, Ghavameddin. "Reliability analysis and economic equipment replacement appraisal for substation and sub-transmission systems with explicit inclusion of non-repairable failures." Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/40848/1/Ghavameddin_Nourbakhsh_Thesis.pdf.
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The modern society has come to expect the electrical energy on demand, while many of the facilities in power systems are aging beyond repair and maintenance. The risk of failure is increasing with the aging equipments and can pose serious consequences for continuity of electricity supply. As the equipments used in high voltage power networks are very expensive, economically it may not be feasible to purchase and store spares in a warehouse for extended periods of time. On the other hand, there is normally a significant time before receiving equipment once it is ordered. This situation has created a considerable interest in the evaluation and application of probability methods for aging plant and provisions of spares in bulk supply networks, and can be of particular importance for substations. Quantitative adequacy assessment of substation and sub-transmission power systems is generally done using a contingency enumeration approach which includes the evaluation of contingencies, classification of the contingencies based on selected failure criteria. The problem is very complex because of the need to include detailed modelling and operation of substation and sub-transmission equipment using network flow evaluation and to consider multiple levels of component failures. In this thesis a new model associated with aging equipment is developed to combine the standard tools of random failures, as well as specific model for aging failures. This technique is applied in this thesis to include and examine the impact of aging equipments on system reliability of bulk supply loads and consumers in distribution network for defined range of planning years. The power system risk indices depend on many factors such as the actual physical network configuration and operation, aging conditions of the equipment, and the relevant constraints. The impact and importance of equipment reliability on power system risk indices in a network with aging facilities contains valuable information for utilities to better understand network performance and the weak links in the system. In this thesis, algorithms are developed to measure the contribution of individual equipment to the power system risk indices, as part of the novel risk analysis tool. A new cost worth approach was developed in this thesis that can make an early decision in planning for replacement activities concerning non-repairable aging components, in order to maintain a system reliability performance which economically is acceptable. The concepts, techniques and procedures developed in this thesis are illustrated numerically using published test systems. It is believed that the methods and approaches presented, substantially improve the accuracy of risk predictions by explicit consideration of the effect of equipment entering a period of increased risk of a non-repairable failure.
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Ben, Salem Aymen. "The Application of Multiuser Detection to Spectrally Efficient MIMO or Virtual MIMO SC-FDMA Uplinks in LTE Systems." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/30351.
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Single Carrier Frequency Division Multiple Access (SC-FDMA) is a multiple access transmission scheme that has been adopted in the 4th generation 3GPP Long Term Evolution (LTE) of cellular systems. In fact, its relatively low peak-to-average power ratio (PAPR) makes it ideal for the uplink transmission where the transmit power efficiency is of paramount importance. Multiple access among users is made possible by assigning different users to different sets of non-overlapping subcarriers. With the current LTE specifications, if an SC-FDMA system is operating at its full capacity and a new user requests channel access, the system redistributes the subcarriers in such a way that it can accommodate all of the users. Having less subcarriers for transmission, every user has to increase its modulation order (for example from QPSK to 16QAM) in order to keep the same transmission rate. However, increasing the modulation order is not always possible in practice and may introduce considerable complexity to the system. The technique presented in this thesis report describes a new way of adding more users to an SC-FDMA system by assigning the same sets of subcarriers to different users. The main advantage of this technique is that it allows the system to accommodate more users than conventional
SC-FDMA and this corresponds to increasing the spectral efficiency without requiring a higher modulation order or using more bandwidth. During this work, special attentions wee paid to the cases where two and three source signals are being transmitted on the same set of subcarriers, which leads respectively to doubling and tripling the spectral efficiency. Simulation results show that by using the proposed technique, it is possible to add more users to any SC-FDMA system without increasing the bandwidth or the modulation order while keeping the same performance in terms of bit error rate (BER) as the conventional SC-FDMA. This is realized by slightly increasing the energy per bit to noise power spectral density ratio (Eb/N0) at the transmitters.
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Sklar, Alexander Gabriel. "Channel Modeling Applied to Robust Automatic Speech Recognition." Scholarly Repository, 2007. http://scholarlyrepository.miami.edu/oa_theses/87.
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In automatic speech recognition systems (ASRs), training is a critical phase to the system?s success. Communication media, either analog (such as analog landline phones) or digital (VoIP) distort the speaker?s speech signal often in very complex ways: linear distortion occurs in all channels, either in the magnitude or phase spectrum. Non-linear but time-invariant distortion will always appear in all real systems. In digital systems we also have network effects which will produce packet losses and delays and repeated packets. Finally, one cannot really assert what path a signal will take, and so having error or distortion in between is almost a certainty. The channel introduces an acoustical mismatch between the speaker's signal and the trained data in the ASR, which results in poor recognition performance. The approach so far, has been to try to undo the havoc produced by the channels, i.e. compensate for the channel's behavior. In this thesis, we try to characterize the effects of different transmission media and use that as an inexpensive and repeatable way to train ASR systems.
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Lai, Yen-Heng, and 賴彥亨. "An OFDMA System with Minimum Mean Square Error via the Common Carrier Frequency Offset Compensation." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/78614395642382544876.
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碩士國立中央大學
通訊工程研究所
96
In recent years, the orthogonal frequency division multiple access (OFDMA) system has been considered as an important technology for future multiuser wireless communications. An OFDMA system with a new carrier frequency offset (CFO) correction scheme is proposed in this thesis. The previous works compensating for the CFO effect at the OFDMA receiver can result in multiple access interference (MAI). Although the MAI cancellation scheme can be used to mitigate the MAI effect, the minimum mean square error (MMSE) performance depends on a common CFO value to be corrected in front of the DFT. We explore the effect of the common CFO and propose a new method to estimate the optimal common CFO at the OFDMA receiver to achieve the MMSE performance. The proposed scheme can decrease the bit error rate (BER) for particular subscribers. Simulation results show that the new algorithm combining MAI cancellation schemes outperforms the past schemes without common CFO correction.
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Lin, Jheng-Yao, and 林政曜. "Utilizing Minimum Mean-Square-Error algorithm and Kalman Filter for channel estimation in Orthogonal Frequency-Division Multiplexing system." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/94895513978379800505.
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碩士淡江大學
電機工程學系碩士班
94
In this report, the channel frequency response of the wireless Orthogonal Frequency-Division Multiplexing system has been estimated and modeled by utilizing the minimum mean-square-error (MSE) algorithm and kalman filtering algorithm. Two channel models have been developed for the system considered, namely, an additive white Gaussian noise only channel and a Rayleigh slow-fading channel with white Gaussian noise added channel. With the models developed several examples have been simulated to study the resulting system symbol error rates vs. signal to noise ratios and fading factors to study the effectiveness of the developed algorithm.
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Botha, P. R. (Philippus Rudolph). "Iterative decoding of space-time-frequency block coded mimo concatenated with LDPH codes." Diss., 2013. http://hdl.handle.net/2263/33344.
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In this dissertation the aim was to investigate the usage of algorithms found in computer
science and apply suitable algorithms to the problem of decoding multiple-input multipleoutput
(MIMO) space-time-frequency block coded signals. It was found that the sphere
decoder is a specific implementation of the A* tree search algorithm that is well known in
computer science. Based on this knowledge, the sphere decoder was extended to include
a priori information in the maximum a posteriori probability (MAP) joint decoding of the
STFC block coded MIMO signals. The added complexity the addition of a priori information
has on the sphere decoder was investigated and compared to the sphere decoder without
a priori information. To mitigate the potential additional complexity several algorithms that
determine the order in which the symbols are decoded were investigated. Three new algorithms
incorporating a priori information were developed and compared with two existing
algorithms. The existing algorithms compared against are sorting based on the norms of the
channel matrix columns and the sorted QR decomposition.
Additionally, the zero forcing (ZF) and minimum mean squared error (MMSE) decoderswith and without decision feedback (DF) were also extended to include a priori information.
The developed method of incorporating a priori information was compared to an existing
algorithm based on receive vector translation (RVT). The limitation of RVT to quadrature
phase shift keying (QPSK) and binary shift keying (BPSK) constellations was also shown in
its derivation. The impact of the various symbol sorting algorithms initially developed for
the sphere decoder on these decoders was also investigated. The developed a priori decoders
operate in the log domain and as such accept a priori information in log-likelihood ratios
(LLRs). In order to output LLRs to the forward error correcting (FEC) code, use of the
max-log approximation, occasionally referred to as hard-to-soft decoding, was made.
In order to test the developed decoders, an iterative turbo decoder structure was used together
with an LDPC decoder to decode threaded algebraic space-time (TAST) codes in a Rayleigh
faded MIMO channel. Two variables that have the greatest impact on the performance of the
turbo decoder were identified: the hard limit value of the LLRs to the LDPC decoder and the
number of independently faded bits in the LDPC code.Dissertation (MEng)--University of Pretoria, 2013.
gm2014
Electrical, Electronic and Computer Engineering
unrestricted
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Silva, Andreia Pereira da. "Low Complexity Iterative Frequency Domain Equalisation for MIMO-OFDM Type Systems." Master's thesis, 2016. http://hdl.handle.net/10316/83157.
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Dissertação de Mestrado Integrado em Engenharia Electrotécnica e de Computadores apresentada à Faculdade de Ciências e TecnologiaAs comunicações sem fios são, sem sombra de dúvida, o segmento de mais rápido crescimento da indústria de comunicações. Não só os telemóveis, que se tornaram uma ferramenta fulcral no mundo dos negócios e parte da vida quotidiana em todo o mundo, mas também os computadores e outros dispositivos de consumo de dados têm vindo a experienciar um crescimento exponencial na última década, trazendo novos desafios para a próxima geração de sistemas sem fios. As redes sem fio de quinta geração como próximo standard deverão ser capazes de satisfazer os requisitos impostos pela crescente procura de maior capacidade, ao mesmo tempo que garantem robustez, fiabilidade e maiores taxas de transferência.Uma das alternativas mais promissoras consiste no aumento do número de antenas tanto no transmissorcomo no recetor, isto é sistemas MIMO, que beneficiam de técnicas de processamento de sinal explorando uma diversidade adicional permitindo uma maior eficiência espectral ou uma transmissão robusta. No que diz respeito à obtenção de taxas de transferência de dados maiores e uma capacidade aumentada, empregando multiplexagem espacial combinada com sistemas OFDM ou que derivem dos mesmos é vista como uma das soluções mais poderosas. Particularmente, quando novas técnicas, como o TIBWB-OFDM, são adotados é possível obter um sistema de comunicação sem fios com uma melhor eficiência espectral e energética, robusto aos desvanecimentos profundos do canal selectivo na frequência.No entanto, existe alguma complexidade computacional inerente aos sistemas MIMO, que aumenta com onúmero de antenas no sistema, tornando o recetor muito mais complexo, nomeadamente na fase de equalização onde equalizadores presentes no estado de arte, como o MMSE e ZF, necessitam de inversões de matrizes de altas dimensões. Para superar este problema, é crucial considerar recetores iterativos, tais como EGC e MRC, que não requerem inversões de matrizes de canal de altas dimensões e, como tal, o recetor pode ser mantido a uma complexidade razoável.Portanto, o objetivo principal deste trabalho é conseguir um sistema com alta eficiência tanto a nívelespectral como a nível energético, capaz de lidar com as deficiências do canal MIMO, enquanto a complexidade do recetor se mantém reduzida através do uso de técnicas que não necessitem de inverter as matrizes de canal. Os resultados obtidos mostraram que empregar equalizadores lineares ou não lineares, tais como o EGC and MRC, permite ganhos substanciais relativamente ao sistema conventional MIMO usando o prefixo cíclico como intervalo de guarda nas mesmas condições. Além disso, os métodos iterativos de baixa complexidade mostraram um melhor desempenho quando usados em esquemas do tipo MIMO TIBWB-OFDM, sendo conseguido um desempenho excelente capaz de aproximar o match filter bound com apenas algumas iterações.
Wireless communications are, by any measure, the fastest growing segment of the communications industry. Not only the cellular phones, which have become a critical business tool and part of everyday lifeworldwide, but also computers and other data consuming devices have experienced exponential growth over the last decade, bringing some new challenges to the next generation wireless systems. Fifth generation wireless networks as the next standard must be able to meet the requirements imposed by the ever increasing demand in capacity, while guaranteeing robustness, reliability and higher data rates.One of the most promising alternatives is the increase in the number of antennas in both transmitterand receiver, i.e. multiple-input multiple-output (MIMO) systems, which leveraged on signal processingtechniques exploring added diversity may allow for higher spectral efficiency or improved robustness transmission. Regarding to achieve higher data rates and an increased capacity, employing spatial multiplexing combined with orthogonal frequency division multiplexing (OFDM) type systems is seen as one of most potential solutions. Particularly, when new techniques, such as the time-interleaved block-windowed burst OFDM (TIBWB-OFDM), are adopted is possible to achieve a highly spectral and power efficient wireless communication system, robust to the deep fades of the selective-frequency channel.However, there is some computational complexity inherent to the MIMO systems, that grows with thenumber of antennas elements, making the receiver much more complex, namely the equalisation stage where state-of-the art equalisers, such as minimum mean squared error (MMSE) and zero forcing (ZF), require for the inversion of the channel’s high dimension matrix. To overcome this problem, it is crucial to consider low complexity frequency-domain iterative receivers, such as equal gain combiner (EGC) and maximum ratio combiner (MRC), which do not require high dimension channel matrices inversions and as so, the receiver can be kept at an affordable complexity.Therefore, the main goal of this work is to achieve a spectral and power efficient system able to handle withthe impairments of the frequency-selective MIMO channel, while keeping the receiver complexity reducedthrough the use of techniques that does not require channel matrix inversions. Performance results shownthat employing linear equalisers or nonlinear equalisers, such as EGC and MRC, allows substantial gainsover the conventional MIMO employing cyclic prefix technique, in the same conditions. Furthermore, lowcomplexity iterative methods have their best performances when employed in the multiple-input multiple- output TIBWB-OFDM (MIMO TIBWB-OFDM) scheme, achieving excellent performance and approachingthe matched filter bound (MFB) with just a few iterations.
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Dutta, Amit Kumar. "Transceiver Design Based on the Minimum-Error-Probability Framework for Wireless Communication Systems." Thesis, 2015. http://etd.iisc.ernet.in/2005/3732.
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Parameter estimation and signal detection are the two key components of a wireless communication system. They directly impact the bit-error-ratio (BER) performance of the system. Several criteria have been successfully applied for parameter estimation and signal detection. They include maximum likelihood (ML), maximum a-posteriori probability (MAP), least square (LS) and minimum mean square error (MMSE) etc. In the linear detection framework, linear MMSE (LMMSE) and LS are the most popular ones. Nevertheless, these criteria do not necessarily minimize the BER, which is one of the key aspect of any communication receiver design. Thus, minimization of BER is tantamount to an important design criterion for a wireless receiver, the minimum bit/symbol error ratio (MBER/MSER). We term this design criterion as the minimum-error-probability (MEP). In this thesis, parameter estimation and signal detection have been extensively studied based on the MEP framework for various unexplored scenar-ios of a wireless communication system. Thus, this thesis has two broad categories of explorations, first parameter estimation and then signal detection. Traditionally, the MEP criterion has been well studied in the context of the discrete signal detection in the last one decade, albeit we explore this framework for the continuous parameter es-timation. We first use this framework for channel estimation in a frequency flat fading single-input single-output (SISO) system and then extend this framework to the carrier frequency offset (CFO) estimation of multi-user MIMO OFDM system. We observe a reasonably good SNR improvement to the tune of 1 to 2.5 dB at a fixed BER (tentatively at 10−3). In this context, it is extended to the scenario of multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) or MIMO-OFDM with pa-rameter estimation error statistics obtained from LMMSE only and checked its effect at the equalizer design using MEP and LMMSE criteria. In the second exploration of the MEP criterion, it is explored for signal detection in the context of MIMO-relay and MIMO systems. Various low complexity solutions are proposed to alleviate the effect of high computational complexity for the MIMO-relay. We also consider various configurations of relay like cognitive, parallel and multi-hop relaying. We also propose a data trans-mission scheme with a rate of 1/Ns (Ns is the number of antennas at the transmitter) with the help of the MEP criterion to design various components. In all these cases, we obtain considerable BER improvement compared to the existing solutions.
Book chapters on the topic "Minimum meal frequency"
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Fedorov, Eugene, Tetyana Utkina, and Tetyana Neskorodeva. "A Voice Signal Filtering Methods for Speaker Biometric Identification." In Recent Advances in Biometrics [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.101975.
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The preliminary stage of the personality biometric identification on a voice is voice signal filtering. For biometric identification are considered and in number investigated the following methods of noise suppression in a voice signal. The smoothing adaptive linear time filtering (algorithm of the minimum root mean square error, an algorithm of recursive least squares, an algorithm of Kalman filtering, a Lee algorithm), the smoothing adaptive linear frequency filtering (the generalized method, the MLEE (maximum likelihood envelope estimation) method, a wavelet analysis with threshold processing (universal threshold, SURE (Stein’s Unbiased Risk Estimator)-threshold, minimax threshold, FDR (False Discovery Rate)-threshold, Bayesian threshold were used), the smoothing non-adaptive linear time filtering (the arithmetic mean filter, the normalized Gauss’s filter, the normalized binomial filter), the smoothing nonlinear filtering (geometric mean filter, the harmonic mean filter, the contraharmonic filter, the α-trimmed mean filter, the median filter, the rank filter, the midpoint filter, the conservative filter, the morphological filter). Results of a numerical research of denoising methods for voice signals people from the TIMIT (Texas Instruments and Massachusetts Institute of Technology) database which were noise an additive Gaussian noise and multiplicative Gaussian noise were received.
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K R, Kaviya, and Deepa S. "An Inclusive Survey on Various Adaptive Beam Forming Algorithm for 5G Communications Systems." In Intelligent Systems and Computer Technology. IOS Press, 2020. http://dx.doi.org/10.3233/apc200182.
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There are several existing wireless system in 5G technology, originating interference in same frequency band and degenerate the concert of received signal. Antenna System comprise of different Beam forming methods in which direction of required signal is generated by the beam and nulls and the voids are set in the direction of unwanted signal (Interference). The survey of different blind and non-blind beam forming algorithms are discussed using smart antenna and phased array. It involves Least Mean Square (LMS), Normalized Least Mean Square (NLMS), Recursive Least Square (RLS), Sample Matrix Inversion(SMI), Linear Constrained Minimum Variance (LCMV), Constant Modulus (CMA), Decision feedback equalization based LMS (DFE-LMS) are considered. These algorithms are outlined to be claimed in 5G network to provide good quality, capacity and dealing with coincidence of signals and interference.
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Paláncz, Béla, Levente Kovács, Balázs Benyó, and Zoltán Benyó. "Robust Blood-Glucose Control of Type I Diabetes Patients Under Intensive Care Using Mathematica." In Encyclopedia of Healthcare Information Systems, 1210–19. IGI Global, 2008. http://dx.doi.org/10.4018/978-1-59904-889-5.ch151.
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This article presents a robust control design method on frequency domain using Mathematica for regularization of glucose level in Type I diabetes persons under intensive care. The method originally proposed under Mathematica by Helton and Merino (1998) is now improved with a disturbance rejection constraint inequality, and is tested on the three-state minimal model. Nonlinear closed loop simulation in state-space, in case of standard meal disturbances, demonstrates the robustness of the resulted high-order linear controller. The obtained results are compared with H8 design implemented with Matlab, proving that the controller (for the considered model parameters) can operate properly, even in case of parameter values of the worst-case scenario.
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Chen, Sheng. "Adaptive Beamforming Assisted ReceiverAdaptive Beamforming." In Handbook on Advancements in Smart Antenna Technologies for Wireless Networks, 60–81. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-59904-988-5.ch003.
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Adaptive beamforming is capable of separating user signals transmitted on the same carrier frequency, and thus provides a practical means of supporting multiusers in a space-division multiple-access scenario. Moreover, for the sake of further improving the achievable bandwidth efficiency, high-throughput quadrature amplitude modulation (QAM) schemes have become popular in numerous wireless network standards, notably, in the recent WiMax standard. This contribution focuses on the design of adaptive beamforming assisted detection for the employment in multiple-antenna aided multiuser systems that employ the high-order QAM signalling. Traditionally, the minimum mean square error (MMSE) design is regarded as the state-of-the-art for adaptive beamforming assisted receiver. However, the recent work (Chen et al., 2006) proposed a novel minimum symbol error rate (MSER) design for the beamforming assisted receiver, and it was demonstrated that this MSER design provides significant performance enhancement, in terms of achievable symbol error rate, over the standard MMSE design. This MSER beamforming design is developed fully in this contribution. In particular, an adaptive implementation of the MSER beamforming solution, referred to as the least symbol error rate algorithm, is investigated extensively. The proposed adaptive MSER beamforming scheme is evaluated in simulation, in comparison with the adaptive MMSE beamforming benchmark.
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Luet Ng, Len, Kim Ho Yeap, Magdalene Wan Ching Goh, and Veerendra Dakulagi. "Power Consumption in CMOS Circuits." In Field-Effect Transistor [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.105717.
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In this chapter, we explain the two types of power consumption found in a complementary metal-oxide-semiconductor (CMOS) circuit. In general, a CMOS circuit tends to dissipate power at all times—be it active or inactive. The power consumed by the circuit when it is performing computational tasks is known as dynamic power. On the contrary, the power lost due to current leakage during which the circuit is dormant is referred to as static power. By carefully and properly designing the circuit, current leakage can be suppressed to its minimum. Hence, dynamic power consumption is usually significantly higher than its static counterpart. Some of the techniques that could be adopted to save dynamic power consumption include reducing the supply voltage, clock frequency, clock power, and dynamic effective capacitance. By probing into the activity factors of the design modules, the techniques can be applied to those with high power consumption.
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Ahmad, Asif. "Application of Taguchi Method in Optimization of Pulsed TIG Welding Process Parameter." In Robust Design Methods [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.93974.
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Pulsed TIG welding is one of the most widely used welding processes in the metal manufacturing industry. In any fusion arc welding process, the bead width plays an important role in determining the welding strength and mechanical properties of the weld joint. This study present optimization of the pulsed TIG welding process parameter using Taguchi Philosophy. AISI 316/3136L austenite stainless steel 4mm is used for welding and for the establishment of the optimum combination of the process parameter and depending upon the functional requirement of the welded joint, the acceptable welded joint should have optimum bead width and minimum heat affected zone (HAZ) etc. An experiment was conducted using different welding condition and a mathematical model was constructed using the data collected from the experiment based on Taguchi L25 orthogonal array. Optimum parameter obtained for bead width is peak current 180 ampere, base current 100 ampere, pulse frequency 125Hz and pulse on time 40%.
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Kumar, Uttam, Nirmal Kumar, V. N. Mishra, and R. K. Jena. "Soil Quality Assessment Using Analytic Hierarchy Process (AHP)." In Interdisciplinary Approaches to Information Systems and Software Engineering, 1–18. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7784-3.ch001.
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Fields with rice-based cropping systems are unique from other wetland or upland soils because they are associated with frequent cycling between wetting and drying under anaerobic and aerobic conditions. This alters the C and N transformations, microbial activities and their diversity, and soil physical properties, depending on the other crop in rotation with rice. This chapter aims to compare the soil quality of vertisols of central plains of Chhattisgarh under rice-wheat and rice-chickpea cropping systems. Soil quality index was developed using analytical hierarchy process (AHP). Five soil quality indicators were selected under minimum datasets including soil organic carbon, mean weight diameter, available water content, available phosphorous and zinc. The results indicated that the rice-chickpea cropping system shows improved soil quality than that of rice-wheat cropping system.
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Ngarakana, Evelyn, Clemence Zimudzi, Shakkie Kativu, and Brita Stedje. "Range Expansion of Catha edulis: Implications on Plant Communities in Upland Zimbabwe." In Plant Invasions and Global Change - Prediction, Interaction and Evaluation [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106546.
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Invasive plants have had significant impacts on vegetation communities of Zimbabwe. A study was undertaken to determine current and potential distribution of C. edulis in Zimbabwe using DIVA GIS and MAXENT, and to determine climatic conditions under which the species thrives, together with. The species population structure and its impact on native species. Results indicate that the species has its highest occurrence frequency in Manicaland Province, followed by Matebeleland South Province. Some 13% occurrence points were recorded at an altitude less than 600 m, 21% at an altitude ranging from 600–999 m, 43% at an altitude between 1000 and 1399 m and 23% at an altitude above 1400 m. C. edulis was recorded in areas of maximum temperature range of 34°C and a minimum of 20°C. The species also occurred in regions with a mean precipitation range as low as 60–300 mm and as high as 1000–1261 mm. Further, C. edulis distribution is predicted to expand in the Eastern Highlands (Manicaland), parts of Mazowe and Bindura (Mashonaland Central Province) and parts of Matobo (Matebelaland South Province). Diameter class distributions showed an inverse J-distribution in control sites and in all three sampled sections. An irregular bell-shaped distribution was recorded for co-occurring species on C. edulis occupied sites. It was concluded that C. edulis’ regeneration potential is high and that of competing native species is unstable and has the potential to expand beyond the currently occupied sites.
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"Balancing Fisheries Management and Water Uses for Impounded River Systems." In Balancing Fisheries Management and Water Uses for Impounded River Systems, edited by Jeffrey W. Quinn and Robert L. Limbird. American Fisheries Society, 2008. http://dx.doi.org/10.47886/9781934874066.ch12.
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<em>Abstract</em>.—We evaluated long-term fisheries data relative to a range of perturbations for the Arkansas River from 1970 to 2006. Rotenone sample sites were located at pool 13 (Garrison Creek), Ozark Lake (Lavaca), and Lake Dardanelle (Panther Cove and the Arkansas Nuclear 1 Effluent Bay). The period of record was 24 years for Garrison Creek and Lavaca, 29 years for Effluent Bay, and 30 years for Panther Cove. Mean total fish biomass ranged between 466 kg/ha and 1,601 kg/ha among sites, and no temporal trends were detected for total biomass. Invasion of zebra mussels <em>Dreissena polymorpha</em>, discovery of largemouth bass virus, and imposition of a 381 mm total length (TL) minimum length limit for largemouth bass <em>Micropterus salmoides </em>likely contributed to notable changes in these fisheries during the past 30 years. Biomass of redear sunfish <em>Lepomis microlophus</em>, freshwater drum <em>Aplodinotus grunniens</em>, and blue catfish <em>Ictalurus furcatus </em>increased in association with the invasion of the river by nonnative zebra mussels. Spotted gar <em>Lepisosteus oculatus </em>and paddlefish <em>Polyodon spathula </em>biomass increased, and common carp <em>Cyprinus carpio </em>biomass declined coincident with the zebra mussel invasion. Large-scale sedimentation of aquatic habitats may have been related to observed declines of backwater-oriented species, especially common carp and spotted gar. The frequency of largemouth bass between 350 and 400 mm TL increased in electrofishing samples after the imposition of a 381-mm-TL minimum length limit, and total catch per hour of largemouth bass greater than 381 mm TL increased. Our associations would suggest that the discovery of largemouth bass virus during 2000 contributed to (1) lower electrofishing catch per hour of largemouth bass greater than 533 mm TL, and (2) an average increase of 420 h required for an angler to catch a 2.27-kg largemouth bass. We anticipate further changes in the Arkansas River during the next decade from the biological invasions of white perch <em>Morone americana</em>, bighead carp <em>Hypophthalmichthys nobilis</em>, and silver carp <em>H. molitrix</em>; increased establishment of aquatic vegetation; and accelerated loss of aquatic habitats associated with planned federal navigation channel improvements.
Conference papers on the topic "Minimum meal frequency"
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Yu, Dong, Li Deng, Jian Wu, Yifan Gong, and Alex Acero. "Improvements on Mel-Frequency Cepstrum Minimum-Mean-Square-Error Noise Suppressor for Robust Speech Recognition." In 2008 6th International Symposium on Chinese Spoken Language Processing (ISCSLP). IEEE, 2008. http://dx.doi.org/10.1109/chinsl.2008.ecp.29.
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Jensen, Jesper, and Zheng-Hua Tan. "A theoretically consistent method for minimum mean-square error estimation of mel-frequency cepstral features." In 2014 4th IEEE International Conference on Network Infrastructure and Digital Content (IC-NIDC). IEEE, 2014. http://dx.doi.org/10.1109/icnidc.2014.7000327.
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Dong Yu, Li Deng, Jasha Droppo, Jian Wu, Yifan Gong, and Alex Acero. "A minimum-mean-square-error noise reduction algorithm on Mel-frequency cepstra for robust speech recognition." In ICASSP 2008 - 2008 IEEE International Conference on Acoustics, Speech and Signal Processing. IEEE, 2008. http://dx.doi.org/10.1109/icassp.2008.4518541.
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Keshani, Shamim, and Nasser Masoumi. "Improved Frequency Accuracy of IFM Using Minimum Mean Squared Error Algorithm." In 2018 Iranian Conference on Electrical Engineering (ICEE). IEEE, 2018. http://dx.doi.org/10.1109/icee.2018.8472591.
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Gao, Hao, Kuangyuan Ying, Marion K. Matters-Kammerer, Pieter Harpe, Qian Ma, Arthur van Roermund, and Peter Baltus. "A 48–61 GHz LNA in 40-nm CMOS with 3.6 dB minimum NF employing a metal slotting method." In 2016 IEEE Radio Frequency Integrated Circuits Symposium (RFIC). IEEE, 2016. http://dx.doi.org/10.1109/rfic.2016.7508274.
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Tan, Ke, Guojin Jiang, Yongbin Sun, Huaqing Peng, and Ji Shi. "Applying Markov Processes for KIC Minimum Configuration Calculation." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-30099.
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CPR1000 plant operation is based on a centralized and computerized control mean (the KIC system), that provides all the means needed by the shift team to operate the plant in any situation. There are two main consequences regarding the definition of the KIC configuration. 1) The KIC composition shall be defined so that they are sufficient for the shift team to finish their tasks. It is linked to “Human Factors” concerns as well as organization concerns. 2) The probability of KIC OWP (Operator Work Place) unavailable shall be taken into account in order to figure out the relationship between the fault leading to KIC OWP unavailable and different KIC degraded situation. The technology and architecture choices fix limits to the flexibility and robustness that the KIC can offer regarding its own degraded situations. Therefore, in order to keep a low frequency of use of the Back-Up Panel, it might be needed to adapt and review the operating organization and needs to stay on the KIC by raising the discomfort of operation for the shift team. Nevertheless, such an approach is limited as reducing the discomfort of operation as obviously a price in term of safety notably. Therefore, the KIC degraded situation shall be studied in order to identify the criteria beyond which the safety operation of the plant cannot be ensured anymore from the KIC. After studying the features of the fault leading to KIC OWP key component unavailable, the data from DCS supplier, the data from reference NPP (Nuclear Power Plant) and the statistic during commissioning, the MTBF (Mean Time Between Failures) for each OWP has been calculated. Applying Markov Processes based on the studying above, CPR1000 operation principles, features of SOP (state oriented procedures to deal with accident situation) and PSA, CNPEC suggest the method to calculate KIC minimum configuration for reaching the best balance to maximize the availability of the KIC, to minimize frequency of switch to the Back-Up Panel (conventional control means) and to increase the plant availability (as the switch to the Back-Up Panel can lead to the fallback of the unit).
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Liu, L., W. H. Zhang, Y. Li, and G. H. Huang. "Study on Frequency Variety Stiffness of Metal Springs." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-86785.
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For the sake of studying dynamic characteristics and the response of dynamic stiffness to driving frequency in metal helical spring, the paper studied on rolling stock spring (helical spring). The paper adopted FEM to establish the finite element model of the spring, calculate out steady-state spring’s response and draw frequency-amplitude characteristic curve of the spring. The results indicate that spring dynamic stiffness is increasing with the increase of driving frequency in general tendency, dynamic stiffness is minimal and smaller than static stiffness corresponding to resonant frequencies and, however, dynamic stiffness is maximal and greater than static stiffness corresponding to anti-resonant frequencies. In order to apply the result in simulation, the paper proposed an equivalent algorithm, compared the calculating result of the equivalent model with one of the spring model and found that the gap between them was very small. So remarkable dynamic characteristic exists in metal helical spring and it is doable to make multi-degree of freedom system be equivalent to continuous spring system.
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Leite, Pierre, Marc Thomas, Frank Simon, and Yves Bréchet. "Optimal Design of an Asymmetrical Sandwich Panel for Acoustical and Mechanical Properties." In ASME 2012 11th Biennial Conference on Engineering Systems Design and Analysis. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/esda2012-82504.
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The aim of the present study is to develop specific tools to design optimal panels for multi-objective applications. The objectives considered are stiffness, strength and acoustic insulation at minimum weight. A genetic algorithm is used to design optimal sandwich structures with a good balance of mechanical and acoustical properties. The bending stiffness and mechanical strength of the panel are calculated using beam theory. This analysis is focused on a 3-point bending test, giving the stiffness as the ratio between the concentrated force and the deflection at the center of the sandwich panel. The strength is calculated as the critical force at the onset of plastic deformation. A vibro-acoustical model based on Lagrange’s equations is used to give access to the sound transmission loss of the sandwich panel with anisotropic elastic layers. The main interest is on the mean transmission loss for a diffused incident acoustic field over the frequency range 500–10000Hz. First of all, the optimal design for mechanical properties is assessed at a minimal weight. Quite expectedly, the best solutions are composite-skin with high specific stiffness and soft cores with high shear modulus for a minimum weight. The geometry depends on the required stiffness and strength. The design/properties relationship is discussed by monitoring the evolution of both the material properties and the geometry of the panel. Similarly, a parametric study is performed for acoustical design at minimal weight. In order to maximize the mean transmission loss, it is preferable to lower the critical frequency for which acoustic radiating is maximal. Then, the best solutions for the panel are those who maximize the square root of the density over Young’s modulus. The trade-off between mass and loss transmission is then explored. A comparison between all these solutions provides significant differences in the design with respect to the objectives. In the next step, a multi-objective genetic algorithm is used to find an optimized panel with a good compromise between acoustical and mechanical properties. The optimization is considered with several approaches depending on whether the mass is regarded as the cost function or as a constraint. This study thus provides a preview of the capabilities of multi-objective optimization in design of sandwich panel.
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Bunce, Nick, Jong Guen Lee, Bryan D. Quay, and Domenic A. Santavicca. "Mixture-Forced Flame Transfer Function Measurements and Mechanisms in a Single-Nozzle Combustor at Elevated Pressure." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46744.
Full textAbstract:
The mixture-forced flame transfer function of a lean fully premixed single-nozzle research combustor operating on natural gas is determined experimentally at combustor pressures from 1 to 4 atm. Measurements are made over a range of inlet temperatures (100–300°C), mean velocities (25–35 m/s), and equivalence ratios (0.5–0.75). A rotating siren device, located upstream of the nozzle, is used to modulate the flow rate of the premixed fuel-air mixture. The amplitude and phase of the resultant velocity fluctuation are measured near the exit of the nozzle using the two-microphone method. The measured normalized velocity fluctuation serves as the input to the flame transfer function. In this study, the amplitude of the normalized velocity fluctuation is fixed at 5% and the modulation frequency is varied from 100 to 500 Hz. The output of the flame transfer function is the normalized global heat release fluctuation, which is measured using a photomultiplier tube and interference filter which captures the CH* chemiluminescence from the entire flame. In addition, two-dimensional CH* chemiluminescence images are taken for both forced and unforced flames. Forced flame images are phase-synchronized with the velocity fluctuation. The flame transfer functions for all of the operating conditions tested exhibit similar behavior. At low frequencies, the gain is initially greater than one, but then decreases as the frequency increases. After reaching a minimum, the gain increases with increasing frequency to a second peak and then again decreases. At certain operating conditions, the gain exhibits a second minimum. At frequencies corresponding to the minima in gain the phase curve exhibits inflection points. Regions of maximum and minimum gain are explained in terms of the constructive and destructive interference of vorticity fluctuations generated in the inner and outer shear layers. Phase-synchronized images are analyzed to isolate the fluctuating component of heat release. At frequencies where the gain is amplified, this analysis shows that the heat release fluctuations caused by the vorticity fluctuations generated in the inner and outer shear layers are in phase. While when the gain is at its minimum value, the heat release fluctuations are out of phase and therefore destructively interfere.
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Yum, Juil, Amir Kamouneh, Wencai Wang, and Elijah Kannatey-Asibu. "Acoustic Emission Condition Monitoring of the Coroning Process." In ASME 2009 International Manufacturing Science and Engineering Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/msec2009-84370.
Full textAbstract:
Acoustic emission (AE) is introduced for tool condition monitoring during the coroning process. The frequency components of the AE signal were used as features for classification. Two different feature selection methods were investigated, namely visual observation and the class mean scatter criterion. The minimum error rate Bayesian rule was used to distinguish between two extreme tool conditions. Although the features from visual observation could result in 100% classification, features based on the class mean scatter criterion showed excellent monitoring capability of tool failure when fewer features were used.