Nonparametric Regression with Dyadic Data

This paper studies the identification and estimation of a nonparametric nonseparable dyadic model where the structural function and the distribution of the unobservable random terms are assumed to be unknown. The identification and the estimation of the distribution of the unobservable random term are also proposed. I assume that the structural function is continuous and strictly increasing in the unobservable heterogeneity. I propose suitable normalization for the identification by allowing the structural function to have some desirable properties such as homogeneity of degree one in the unobservable random term and some of its observables. The consistency and the asymptotic distribution of the estimators are proposed. The finite sample properties of the proposed estimators in a Monte-Carlo simulation are assessed

Morphotropic phase boundary in (1-x)Bi0.5Na0.5TiO3-xK(0.5)Na(0.5)NbO(3) lead-free piezoceramics

The electromechanical behavior of (1-x)Bi0.5Na0.5TiO3-xK(0.5)Na(0.5)NbO(3) (BNT-KNN) lead free piezoelectric ceramics is investigated for 0 <= x <= 0.12 to gain insight into the antiferroelectric-ferroelectric (AFE-FE) phase transition on the basis of the giant strain recently observed in BNT-based systems. At x approximate to 0.07, a morphotropic phase boundary (MPB) between a rhombohedral FE phase and a tetragonal AFE phase is found. While the piezoelectric coefficient is largest at this MPB, the total strain further increases with increasing KNN content, indicating the field-induced AFE-FE transition as the main reason for the large strain.open756

Lead-free piezoceramics with giant strain in the system Bi0.5Na0.5TiO3-BaTiO3-K0.5Na0.5NbO3. I. Structure and room temperature properties

Lead-free piezoelectric ceramics, (1-x-y)Bi0.5Na0.5TiO3-xBaTiO(3)-yK(0.5)Na(0.5)NbO(3) (0.05 <= x <= 0.07 and 0.01 <= y <= 0.03), have been synthesized by a conventional solid state sintering method. The room temperature ferroelectric and piezoelectric properties of these ceramics were studied. Based on the measured properties, the ceramics were categorized into two groups: group I compositions having dominant ferroelectric order and group II compositions displaying mixed ferroelectric and antiferroelectric properties at room temperature. A composition from group II near the boundary between these two groups exhibited a strain as large as similar to 0.45% at an electric field of 8 kV/mm. Polarization in this composition was not stable in that the piezoelectric coefficient d(33) at zero electric field was only about 30 pm/V. The converse piezoelectric response becomes weaker when the composition deviated from the boundary between the groups toward either the ferroelectric or antiferroelectric compositions. These results were rationalized based on a field induced antiferroelectric-ferroelectric phase transition.open12510

Lead-free piezoceramics with giant strain in the system Bi0.5Na0.5TiO3-BaTiO3-K0.5Na0.5NbO3. II. Temperature dependent properties

The temperature dependence of the dielectric and ferroelectric properties of lead-free piezoceramics of the composition (1-x-y)Bi0.5Na0.5TiO3-xBaTiO(3)-yK(0.5)Na(0.5)NbO(3) (0.05 <= x <= 0.07, 0.01 <= y <= 0.03) was investigated. Measurements of the polarization and strain hystereses indicate a transition to predominantly antiferroelectric order when heating from room temperature to 150 degrees C, while for 150 < T < 200 degrees C both remnant polarization and coercive field increase. Frequency-dependent susceptibility measurements show that the transition is relaxorlike. For some samples, the transition temperature T-d is high enough to allow mostly ferroelectric ordering at room temperature. These samples show a drastic increase of the usable strain under an external electric field just after the transition into the antiferroelectric state at high temperatures. For the other samples, T-d is so low that they display significant antiferroelectric ordering already at room temperature. In these samples, the usable strain is relatively stable over a wide temperature range. In contrast to T-d, the temperature T-m of the transition into the paraelectric high-temperature phase depends far less on the sample composition. These results confirm that the high strain in this lead-free system is due to a field-induced antiferroelectric-ferroelectric phase transition and that this effect can be utilized in a wide temperature range.open8

Wearing Judogi in a Humid Tropical Environment: Effect on Performance and Hydro-Electrolytic Parameters

Topics in Exercise Science and Kinesiology Volume 3: Issue 1, Article 8, 2022. Extremely high heat stress environmental conditions in sub-Saharan Africa influences sports performance. The aim of this study was to assess physical changes and physiological responses associated with wearing judogi during 8 weeks training session in a hot environment. In this quasi-experimental study, trained male judokas (20.06 ± 1.24 years old), were assessed before and after a training session, while either wearing a judogi (experimental group n = 12) or cotton tee shorts (control group n = 12). All athletes completed testing and were evaluated for anthropometric, physiological and urine parameters. A significant decrease in body mass (BM) (P.02) was observed in the experimental group but not the control group. In contrast, VO2max was significantly improved in the control group (p = 0.018). Special Judo Fitness Test indicators of athletes in the experimental group were lower than those in the control group (p\u3c0.01) after the 8 weeks training. In addition, significant decreases in sodium (Na+) (p = 0.005), potassium (K+) (p\u3c0.001) and chloride (Cl-) (p\u3c0.001) ion concentration were found in athletes in the experimental group. Body mass, fitness and hydroelectrolytic parameters decreased during those 24 training sessions in judogi wearing athletes. Wearing a judogi and training in open environments in a hot environment impairs judo performance

Effects of “living high-training low” on male/female obese adolescent’s morphological indices and glucose/lipid metabolism

Abstract Objective:This study aims to investigate the effects of 4 weeks living high-training low (HiLo) on obese adolescent’s body composition, glucose/lipid metabolism and gender differences. Method: 37 overweight and obese adolescents (13-16 old), volunteers participated in the fully closed weight-loss exercises. They were randomly divided into two groups as the normal oxygen group (n=19) and hypoxia group (n=18) and exercised an intervention for four-weeks. For the normal oxygen group, aerobic exercises and diet control intervention methods were used. Exercise intensity and individualized exercise prescription were based upon subject health condition and exercise tolerance test. Dieticians according to subject basal metabolic rate formulated a reasonable diet to ensure the calories and essential nutrient supply. For the hypoxia group, except aerobic exercise and diet control intervention, every night the subjects lived in hypoxic room equipped with hypoxia systems and they were exposed to an altitude of about 2,700 m (10 hours per day) for 4 weeks. Before and after hypoxic exposure, obesity related morphological and blood biochemical indices (blood glucose, blood lipid panel (includes 4 main lipoproteins,etc)) were separately analyzed, calculate homeostasis model assessment was used to estimate insulin resistance (HOMA-IR) and insulin secretion (HOMA-β) index. Results: (1) After hypoxia intervention, morphological indices, immunology indices, blood insulin and blood fat in average significantly decreased in both groups; Moreover blood glucose did not change significantly. In normal oxygen group and hypoxia group ,HOMA-IR and HOMA-β index significantly decreased. (2) Hypoxia combined with exercise and alimentary control have different effects on male/female obese adolescent’s morphological indices and glucose/lipid metabolism that were shown by: 1. Male in hypoxia group showed weight, BMI and body fat significantly decreased more than normal oxygen group, the two groups lean body mass did not change significantly. Moreover, female in hypoxia group showed lean body mass significantly decreased more than normal oxygen group, the two group’s weight, BMI and body fat did not change significantly. 2. Between the two groups, for male subjects HOMA-IR and HOMA-β index did not change significantly; in hypoxia group, for female subjects HOMA-β index decreased, but there was an upward trend in normal oxygen group, the two groups change significantly. Conclusion: (1) The two interventions methods can significantly improve the obese adolescent’s morphological and glucose/lipid metabolism indices. (2) The effects of the two interventions methods on morphological and glucose/lipid metabolism indices are due to gender differences, it should be used selectively based on the current situation

Advances in Lead-Free Piezoelectric Materials for Sensors and Actuators

Piezoelectrics have widespread use in today’s sensor and actuator technologies. However, most commercially available piezoelectric materials, e.g., Pb [ZrxTi1−x] O3 (PZT), are comprised of more than 60 weight percent lead (Pb). Due to its harmful effects, there is a strong impetus to identify new lead-free replacement materials with comparable properties to those of PZT. This review highlights recent developments in several lead-free piezoelectric materials including BaTiO3, Na0.5Bi0.5TiO3, K0.5Bi0.5TiO3, Na0.5K0.5NbO3, and their solid solutions. The factors that contribute to strong piezoelectric behavior are described and a summary of the properties for the various systems is provided