1,442 research outputs found
Forecast and Monte Carlo simulation of ZaĂŻre river flow
En se basant sur les mesures du débit journalier du Zaïre à Kinshasa, un modèle autorégressif périodique (modèle du type Par) est construit, qui permet la simulation Monte Carlo de séries de débit de longue durée (1 000 années par exemple), ainsi que le calcul de prévisions ponctuelles et d'intervalles de prévision, le tout à l'échelle mensuelle ou hebdomadaire. Les tests sur les distributions mensuelles et hebdomadaires ainsi que sur les volumes d'eau maximaux et minimaux de différente durée donnent des résultats positifs. Par rapport aux résultats obtenus dans le passé les prévisions sont meilleures. Un essai d'amélioration de ces prévisions à l'aide de données pluviométriques en plusieurs stations du bassin se solde par un échec ; ceci est attribué à la lenteur de la réponse du fleuve. En utilisant des résultats obtenus dans le passé, les débits à Inga et Boma sont obtenus. Les prévisions sont utiles lors de la planification du dragage en aval de Boma en vue de maintenir la navigation. Elles sont utiles aussi pour le contrôle en temps réel de la centrale hydro-électrique à Inga. La série simulée peut être utilisée pour faire fonctionner cette centrale d'une façon optimale. Les modèles développés peuvent être mis en oeuvre facilement sans exigences spéciales concernant la rapidité de calcul ou la capacité de mémoire. (Résumé d'auteur
Activation of glucocorticoid receptors is associated with the suppression of antioxidant responses in the liver of goats fed a high-concentrate diet
This study investigated changes in oxidative stress and the relevant mechanisms in the liver of goats fed a high-concentrate (HC) diet for 5 weeks. Twelve goats were randomly assigned to a low-concentrate (concentrate-to-forage = 55:45, LC, n = 6) or HC diet (concentrate-to-forage = 90:10, n = 6), with dry matter as the base. Enzyme activity assays, real-time polymerase chain reaction and western blotting were used to evaluate antioxidant parameters and gene expression in the liver. Superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), total nitric oxide synthase activity and total antioxidant capacity (T-AOC) in the liver declined (p < .01) in HC-fed goats compared to those in LC-fed goats. The mRNA levels of GPX1, CAT and SOD1 were down-regulated (3.69, 47.37 and 27.61%, respectively) in HC-fed goats compared to those in LC-fed goats. Furthermore, glutathione S-transferase M1 (GSTM1) was upregulated (466.35%, p < .01) in the liver of HC-fed goats. The mRNA and protein levels of the nuclear factor E2-related factor 2 (NRF2) and total glucocorticoid receptor (GR) declined (p < .05) in HC-fed goats (by 28.57, 33.1, 30.85 and 34%, respectively). However, the nuclear translocation of GR increased (p < .05; by 44.75%) in HC-fed goats. Negative correlations were detected for hepatic nuclear GR protein expression with hepatic CAT activity and GPx activity. In conclusion, feeding an HC diet to goats for 5 weeks suppressed NRF2-dependent antioxidant responses and enhanced GR nuclear translocation in the liver
Degradation of Inorganic Nitrogen in Beiyun River of Beijing, China
AbstractNitrogen pollution characteristics of Beiyun River and the migration of inorganic nitrogen in sediment-water were studied using laboratory experiment. Extract NH4-N was the dominant pollutants in Beiyun River that caused the severe harm to aquatic system. NH4-N exchange in sediment-water system was observable at different sites. The calculating of NH4-N degradation coefficients showed there was little difference of NH4-N degradation rate at three sites of Beiyun River. Nitrification process was mainly occurred in 12 days and NH4-N can rapidly in the degradation without input
Human body composition models and methodology : theory and experiment
The study of human body composition is a branch of human biology which focuses on the in vivo quantification of body components, the quantitative relationships between components, and the quantitative changes in these components related to various influencing factors. Accordingly, the study of human body composition is composed of three interrelated research areas, body composition rules, body composition methodology, and body composition alterations. This thesis describes the authors recent investigations related to the first two of the three research areas. In the rules area, this thesis begins with a comprehensive five-level model of body composition. The approximate 40 body components are systematically organized into five levels with increasing complexity: 1, atomic; 11, molecular; III, cellular; IV, tissue-system; and V 1 whole-body. Although each level and its multiple components are distinct, interconnections exist such that the model is consistent and functions as a whole. The model provides the opportunity to define clear body composition concepts and to create explicit body composition equations. As an example of a body composition rule, this thesis subsequently explores the magnitude and constancy of the proportion of adipose tissue-free body mass as skeletal muscle mass in young healthy adults.In the methodology area, this thesis begins with a systematic organization of body composition methods. The proposed classification divides the methods into in vitro and in vivo categories, advances to organization- by measurable quantity (property and/or component), and ends with grouping of methods by mathematical function which may be statistically-derived or model-based. This classification system explains both similarities and differences between the many diverse methods, and provides a framework and a setting for all body composition methods. As an example of new body composition method development, the subsequent chapter creates a simple and safe method for predicting total body oxygen mass from body weight and total body water. The remaining four chapters deal with the evaluation of body composition methods. A six-compartment model based on in vivo neutron activation analysis is applied as the reference for inter-method comparisons against sixteen existing methods for estimating total body fat mass. An advanced technique, multiscan computerized axial tomography, is applied as the reference to evaluate existing skeletal muscle mass methods, including the Burkinshaw-Cohn neutron activation model, dual-energy X-ray absorptiometry, 24-hour urinary creatinine excretion, and 24-hour urinary 3-methylhistidine excretion methods.This thesis, therefore, suggests that both theoretical and experimental investigations provide insight into human body composition
Compatibility Issues With Irregular Current Injection Islanding Detection Methods in Multi-DG Units Equipped With Grid-Connected Transformers
Compatibility issues with irregular current injection islanding detection methods are actually the problem that some irregular currents at the same frequency injected into the same line may cancel each other out and then the islanding detection may be impaired, which have been discussed under direct couple conditions (i.e., conditions without grid-connected transformers) in the literature. This article analyzes the issues under the opposite conditions where distributed generation (DG) units are equipped with grid-connected transformers, and is aimed at finding a solution. The analysis derives the setting formulas of key parameters for both three-phase and single-phase DG units, and shows that considering fault tolerance and practicability, only specific frequencies can be used for irregular currents. The usable frequencies are different under different cases. These conclusions are different from those based on direct couple conditions. By summarizing the conclusions based on conditions with grid-connected transformers achieved in this article and those based on direct couple conditions in the literature, a complete solution to compatibility issues is obtained. The conclusions in this article have been verified by the experiments and simulations at the end of this article
Managing human resources across cultures: A comparative analysis of practices in industrial enterprises in China and the Netherlands.
Leaf- and plant-level carbon gain in yellow birch, sugar maple, and beech seedlings from contrasting forest litght environments
Leaf-level photosynthetic-light response and plant-level daily carbon gain were estimated for seedlings of moderately shade-tolerant yellow birch (Betula alleghaniensis Britton) and shade-tolerant sugar maple (Acer saccharum Marsh.) and beech (Fagus grandifolia Ehrh.) growing in gaps and under a closed canopy in a sugar maple stand at Duchesnay, Que. All three species had a higher photosynthetic capacity (A(max)) in the gaps than in shade, but yellow birch and beech responded more markedly than sugar maple to the increase in light availability. The high degree of plasticity observed in beech suggests that the prediction that photosynthetic plasticity should decrease with increasing shade tolerance may not hold when comparisons are made among a few late-successional species. Unit-area daily carbon gain (C(A)) was significantly higher in the gaps than in shade for all three species, but no significant difference was observed between light environments for plant-level carbon gain (C(W)). In shade, we found no difference of C(A) and C(W) among species. In gaps, beech had a significantly higher C(A) than sugar maple but similar to that of birch, and birch had a significantly higher C(W) than maple but similar to that of beech. Sugar maple consistently had lower carbon gains than yellow birch and beech but is nevertheless the dominant species at our study site. These results indicate that although plant-level carbon gain is presumably more closely related to growth and survival of a species than leaf-level photosynthesis, it is still many steps removed from the ecological success of a species
Noise-robust method for image segmentation
Segmentation of noisy images is one of the most challenging problems in image analysis and any improvement of segmentation methods can highly influence the performance of many image processing applications. In automated image segmentation, the fuzzy c-means (FCM) clustering has been widely used because of its ability to model uncertainty within the data, applicability to multi-modal data and fairly robust behaviour. However, the standard FCM algorithm does not consider any information about the spatial linage context and is highly sensitive to noise and other imaging artefacts. Considering above mentioned problems, we developed a new FCM-based approach for the noise-robust fuzzy clustering and we present it in this paper. In this new iterative algorithm we incorporated both spatial and feature space information into the similarity measure and the membership function. We considered that spatial information depends on the relative location and features of the neighbouring pixels. The performance of the proposed algorithm is tested on synthetic image with different noise levels and real images. Experimental quantitative and qualitative segmentation results show that our method efficiently preserves the homogeneity of the regions and is more robust to noise than other FCM-based methods
PENGGUNAAN BAHAN AJAR DALAM PEMBELAJARAN IPS SMP BERBASIS KONTEKSTUAL PADA SISWA KELAS VII SMP NEGERI 1 PURWANTORO WONOGIRI
This research aim: 1. Describe how teacher use the teaching material in
Social Subject in Junior High School 1 Purwantoro up until now. 2.
Describe the constraint and how to overcome it. 3. Describe the usage
result of the teaching material in study of Social for Junior High School
in Purwantoro 1 Junior High School.
This research takes place in Purwantoro 1 Junior High School, Wonogiri
Regency. This research metod is descriptive research of qualitative. This
research wants to describe and expose the usage of teaching material in
study of Contextual Based Social for Junior High School in Purwantoro
1 Junior High School according to the condition and the situation at the
moment.
Strategies utilized in this research are interviewing, question airing,
observing, and documenting.
The result of this research concludes that teaching material in Study of
Contextual Based Social for Junior High School in Purwantoro 1 Junior
High School, evaluated from its form covered : a). Printed teaching
material consist. b). Heard Teaching Material (audio) consist. c) Visual
and Listening Teaching Material consist. d). Interactive teaching
material like compact disc (doesn’t yet able to be executed) e).
Environment teaching material (geography, history, and economics) still
applied in class theory level.
Current result achieved from the use of teaching materials in learning
of Social for Junior High School in Purwantoro Junior High School are:
1) Provide better learning environment for teachers and students. 2)
Help students and make them easy to learn Social. 3) Improve student’s
learning achievement proved with 79,895 average score (it exceeds
current KKM set by the teachers: 72)
Keywords : The Use of, Teaching Materials of Contextual Based Social
for Junior High School
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