On discrete control of nonlinear systems with applications to robotics

Much progress has been reported in the areas of modeling and control of nonlinear dynamic systems in a continuous-time framework. From implementation point of view, however, it is essential to study these nonlinear systems directly in a discrete setting that is amenable for interfacing with digital computers. But to develop discrete models and discrete controllers for a nonlinear system such as robot is a nontrivial task. Robot is also inherently a variable-inertia dynamic system involving additional complications. Not only the computer-oriented models of these systems must satisfy the usual requirements for such models, but these must also be compatible with the inherent capabilities of computers and must preserve the fundamental physical characteristics of continuous-time systems such as the conservation of energy and/or momentum. Preliminary issues regarding discrete systems in general and discrete models of a typical industrial robot that is developed with full consideration of the principle of conservation of energy are presented. Some research on the pertinent tactile information processing is reviewed. Finally, system control methods and how to integrate these issues in order to complete the task of discrete control of a robot manipulator are also reviewed

Effect of foot angle changes on body joints and segments during standing and running = Effet de changement d'angle au pied sur les articulations et les segments lors de l'équilibre debout et de la course

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal

Effect of lateral wedge insole with different inclination on foot kinematics using Principal Component Analysis

زمینه و هدف: بر هم خوردن مقدار و زمان پرونیشن پا ممکن است منجر به استئوآرتریت زانو شود که برای درمان آن از مداخلاتی مانند گوه جانبی در ناحیه پا استفاده می‌‌‌‌شود. تاکنون نتایج مطالعات متناقض بوده‌‌‌‌اند که احتمالاً ناشی از شیب‌‌‌‌های مختلف گوه و تکنیک‌‌‌‌های استفاده شده می‌‌‌‌باشد. مطالعه حاضر با هدف بررسی تأثیر گوه جانبی پا با شیب‌‌‌‌های مختلف بر کینماتیک پا با استفاده از تکنیک آنالیز مولفه‌‌‌‌های اصلی (PCA) انجام شد. روش بررسی: 75 فرد سالم در این مطالعه شرکت کردند. سینماتیک اندام تحتانی آزمودنی‌‌‌‌ها در 5 حالت دویدن با کفش و کفش با گوه جانبی با شیب‌‌‌‌های 3، 6، 9 و 11 درجه در قسمت پاشنه کفش، ثبت شد. سپس با استفاده از روش آماری PCA مولفه‌‌‌‌های اصلی پرونیشن محاسبه شد. برای بررسی اثر گوه بر اورژن و شاخص پرونیشن (مولفه اول PCA) از آنالیز واریانس با داده‌های تکراری استفاده شد. یافته ها: گوه‌‌‌‌های 9 و 11 درجه موجب افزایش معنی دار زاویه اورژن شدند. هنگام بررسی شاخص پرونیشن علاوه بر گوه‌‌‌‌های 9 و 11 درجه، گوه 6 درجه نیز با حالت بدون گوه افزایش معنی داری نشان داد. روش PCA مشخص کرد که گوه 6 درجه، علاوه بر اثرات کلینیکی گزارش شده، بر مکانیک پا نیز اثر می‌‌‌‌گذارد. نتیجه گیری: اورژن پا به تنهایی قادر به بیان تأثیر گوه‌‌‌‌های جانبی بر پا نمی‌‌‌‌باشد و برای به دست آوردن نتایج دقیق‌‌‌‌تر باید تمامی صفحات حرکتی در نظر گرفته شود. روش PCA می‌‌‌‌تواند معیار دقیق‌‌‌‌تری برای بررسی پرونیشن فراهم کند

DETERMINATION OF FUNCTIONAL GROUPS IN DIFFERENT LEVELS IN RUNNING GAIT; LOWER LIMB MECHANICAL ENERGY ANALYSIS

The purpose of this study was to determine the functional groups in different levels during stance phase of running. 118 students (58 males and 60 females) ran in two footwear conditions (Nike free5 and Vibram FiveFingers shoes) and barefoot. Mechanical energy of pelvic, thigh, leg and right foot were calculated. Functional groups were determined using principal component analysis, self-organizing maps, k-means clustering and support vector machine methods based on lower limb mechanical energy. Five first level functional groups were defined in barefoot, Nike and FiveFinger running conditions with accuracy of 95.80%, 91.60% and 91.60%, respectively. 41 subjects were identified as the third level functional groups. According to our results, the functional groups were well recognized with the use of dimension reduction and unsupervised clustering methods

Control of quantum interference frequency combs : multistable temporal cavity solitons

Two branches of bistable temporal cavity solitons are found in models of quantum interference in microresonators with a Λ three-level medium in the anomalous dispersion regime. The cavity solitons are due to the locking of moving domain walls. We identify two distinct Maxwell points on opposite sides of the cavity resonance where domain walls are stationary and two distinct temporal cavity solitons, one narrow and with a high peak intensity, the other broader and with a lower peak intensity, coexist over wide parameter ranges and without the need of secondary cavity resonances. Localized structures combining the two soliton branches oscillate on timescales of tens of cavity round trips. Frequency combs generated by combinations of different types of multistable temporal cavity solitons lead to enhanced bandwidths and their control

Decomposing socioeconomic inequality in poor mental health among Iranian adult population: results from the PERSIAN cohort study

Background Socioeconomic inequality in mental health in Iran is poorly understood. This study aimed to assess socioeconomic inequality in poor mental health among Iranian adults. Methods The study used the baseline data of PERSIAN cohort study including 131,813 participants from 17 geographically distinct areas of Iran. The Erreygers Concentration index (E) was used to quantify the socioeconomic inequalities in poor mental health. Moreover, we decomposed the E to identify factors contributing to the observed socioeconomic inequality in poor mental health in Iran. Results The estimated E for poor mental health was - 0.012 (95% CI: - 0.0144, - 0.0089), indicating slightly higher concentration of mental health problem among socioeconomically disadvantaged adults in Iran. Socioeconomic inequality in poor mental health was mainly explained by gender (19.93%) and age (12.70%). Region, SES itself, and physical activity were other important factors that contributed to the concentration of poor mental health among adults with low socioeconomic status. Conclusion There exists nearly equitable distribution in poor mental health among Iranian adults, but with important variations by gender, SES, and geography. These results suggested that interventional programs in Iran should focus on should focus more on socioeconomically disadvantaged people as a whole, with particular attention to the needs of women and those living in more socially disadvantaged regions. Keywords:Mental health; Socioeconomic inequality; Concentration index; Decompositio

Repositioning of the global epicentre of non-optimal cholesterol

High blood cholesterol is typically considered a feature of wealthy western countries1,2. However, dietary and behavioural determinants of blood cholesterol are changing rapidly throughout the world3 and countries are using lipid-lowering medications at varying rates. These changes can have distinct effects on the levels of high-density lipoprotein (HDL) cholesterol and non-HDL cholesterol, which have different effects on human health4,5. However, the trends of HDL and non-HDL cholesterol levels over time have not been previously reported in a global analysis. Here we pooled 1,127 population-based studies that measured blood lipids in 102.6 million individuals aged 18 years and older to estimate trends from 1980 to 2018 in mean total, non-HDL and HDL cholesterol levels for 200 countries. Globally, there was little change in total or non-HDL cholesterol from 1980 to 2018. This was a net effect of increases in low- and middle-income countries, especially in east and southeast Asia, and decreases in high-income western countries, especially those in northwestern Europe, and in central and eastern Europe. As a result, countries with the highest level of non-HDL cholesterol—which is a marker of cardiovascular risk—changed from those in western Europe such as Belgium, Finland, Greenland, Iceland, Norway, Sweden, Switzerland and Malta in 1980 to those in Asia and the Pacific, such as Tokelau, Malaysia, The Philippines and Thailand. In 2017, high non-HDL cholesterol was responsible for an estimated 3.9 million (95% credible interval 3.7 million–4.2 million) worldwide deaths, half of which occurred in east, southeast and south Asia. The global repositioning of lipid-related risk, with non-optimal cholesterol shifting from a distinct feature of high-income countries in northwestern Europe, north America and Australasia to one that affects countries in east and southeast Asia and Oceania should motivate the use of population-based policies and personal interventions to improve nutrition and enhance access to treatment throughout the world

Repositioning of the global epicentre of non-optimal cholesterol

High blood cholesterol is typically considered a feature of wealthy western countries(1,2). However, dietary and behavioural determinants of blood cholesterol are changing rapidly throughout the world(3) and countries are using lipid-lowering medications at varying rates. These changes can have distinct effects on the levels of high-density lipoprotein (HDL) cholesterol and non-HDL cholesterol, which have different effects on human health(4,5). However, the trends of HDL and non-HDL cholesterol levels over time have not been previously reported in a global analysis. Here we pooled 1,127 population-based studies that measured blood lipids in 102.6 million individuals aged 18 years and older to estimate trends from 1980 to 2018 in mean total, non-HDL and HDL cholesterol levels for 200 countries. Globally, there was little change in total or non-HDL cholesterol from 1980 to 2018. This was a net effect of increases in low- and middle-income countries, especially in east and southeast Asia, and decreases in high-income western countries, especially those in northwestern Europe, and in central and eastern Europe. As a result, countries with the highest level of non-HDL cholesterol-which is a marker of cardiovascular riskchanged from those in western Europe such as Belgium, Finland, Greenland, Iceland, Norway, Sweden, Switzerland and Malta in 1980 to those in Asia and the Pacific, such as Tokelau, Malaysia, The Philippines and Thailand. In 2017, high non-HDL cholesterol was responsible for an estimated 3.9 million (95% credible interval 3.7 million-4.2 million) worldwide deaths, half of which occurred in east, southeast and south Asia. The global repositioning of lipid-related risk, with non-optimal cholesterol shifting from a distinct feature of high-income countries in northwestern Europe, north America and Australasia to one that affects countries in east and southeast Asia and Oceania should motivate the use of population-based policies and personal interventions to improve nutrition and enhance access to treatment throughout the world.Peer reviewe

Height and body-mass index trajectories of school-aged children and adolescents from 1985 to 2019 in 200 countries and territories: a pooled analysis of 2181 population-based studies with 65 million participants

Summary Background Comparable global data on health and nutrition of school-aged children and adolescents are scarce. We aimed to estimate age trajectories and time trends in mean height and mean body-mass index (BMI), which measures weight gain beyond what is expected from height gain, for school-aged children and adolescents. Methods For this pooled analysis, we used a database of cardiometabolic risk factors collated by the Non-Communicable Disease Risk Factor Collaboration. We applied a Bayesian hierarchical model to estimate trends from 1985 to 2019 in mean height and mean BMI in 1-year age groups for ages 5–19 years. The model allowed for non-linear changes over time in mean height and mean BMI and for non-linear changes with age of children and adolescents, including periods of rapid growth during adolescence. Findings We pooled data from 2181 population-based studies, with measurements of height and weight in 65 million participants in 200 countries and territories. In 2019, we estimated a difference of 20 cm or higher in mean height of 19-year-old adolescents between countries with the tallest populations (the Netherlands, Montenegro, Estonia, and Bosnia and Herzegovina for boys; and the Netherlands, Montenegro, Denmark, and Iceland for girls) and those with the shortest populations (Timor-Leste, Laos, Solomon Islands, and Papua New Guinea for boys; and Guatemala, Bangladesh, Nepal, and Timor-Leste for girls). In the same year, the difference between the highest mean BMI (in Pacific island countries, Kuwait, Bahrain, The Bahamas, Chile, the USA, and New Zealand for both boys and girls and in South Africa for girls) and lowest mean BMI (in India, Bangladesh, Timor-Leste, Ethiopia, and Chad for boys and girls; and in Japan and Romania for girls) was approximately 9–10 kg/m2. In some countries, children aged 5 years started with healthier height or BMI than the global median and, in some cases, as healthy as the best performing countries, but they became progressively less healthy compared with their comparators as they grew older by not growing as tall (eg, boys in Austria and Barbados, and girls in Belgium and Puerto Rico) or gaining too much weight for their height (eg, girls and boys in Kuwait, Bahrain, Fiji, Jamaica, and Mexico; and girls in South Africa and New Zealand). In other countries, growing children overtook the height of their comparators (eg, Latvia, Czech Republic, Morocco, and Iran) or curbed their weight gain (eg, Italy, France, and Croatia) in late childhood and adolescence. When changes in both height and BMI were considered, girls in South Korea, Vietnam, Saudi Arabia, Turkey, and some central Asian countries (eg, Armenia and Azerbaijan), and boys in central and western Europe (eg, Portugal, Denmark, Poland, and Montenegro) had the healthiest changes in anthropometric status over the past 3·5 decades because, compared with children and adolescents in other countries, they had a much larger gain in height than they did in BMI. The unhealthiest changes—gaining too little height, too much weight for their height compared with children in other countries, or both—occurred in many countries in sub-Saharan Africa, New Zealand, and the USA for boys and girls; in Malaysia and some Pacific island nations for boys; and in Mexico for girls. Interpretation The height and BMI trajectories over age and time of school-aged children and adolescents are highly variable across countries, which indicates heterogeneous nutritional quality and lifelong health advantages and risks

Diminishing benefits of urban living for children and adolescents’ growth and development

Optimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1–6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5–19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for boys in most countries in sub-Saharan Africa and in some countries in Oceania, south Asia and the region of central Asia, Middle East and north Africa. In these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was <1.1 kg m–2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified