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68982. Time of concentration of surface flow in complex hillslopes
- Creator:
- Sabzevari, Touraj, Saghafian, Bahram, Talebi, Ali, and Ardakanian, Reza
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- complex hillslopes, time of concentration, and surface flow
- Language:
- Slovak
- Description:
- Time of concentration (TC) of surface flow in watersheds depends on the coupled response of hillslopes and stream networks. The important point in this background is to study the effects of the geometry and the shape of complex hillslopes on the time of concentration considering the degree of flow convergence (convergent, parallel or divergent) as well as the profile curvature (concave, straight or convex). In this research, the shape factor of complex hillslopes as introduced by Agnese et al. (2007) is generalized and linked to the TC. A new model for calculating TC of complex hillslopes is presented, which depends on the plan shape, the type and degree of profile curvature, the Manning roughness coefficient, the flow regime, the length, the average slope, and the excess rainfall intensity. The presented model was compared to that proposed by Singh and Agiralioglu (1981a,b) and Agiralioglu (1985). Moreover, the results of laboratory experiments on the travel time of surface flow of complex hillslopes were used to calibrate the model. The results showed that TC for convergent hillslopes is nearly double those of parallel and divergent ones. TC in convex hillslopes was very close to that in straight and concave hillslopes. While the effect of convergence on TC is considerable, the curvature effect confirmed insignificant. Finally, in convergent hillslopes, TC increases with the degree of convergence, but in divergent hillslopes, it decreases as degree of divergence increases.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
68983. Time of oviposition and reproductive success in Argiope bruennichi (Araneae: Araneidae)
- Creator:
- Leborgne, Raymond and Pasquet , Alain
- Type:
- article, model:article, and TEXT
- Subject:
- Time of oviposition, food intake, egg production, orb-web spiders, Argiope bruennichi, and Araneidae
- Language:
- English
- Description:
- Time of oviposition and investment in reproduction output are a crucial decision for animals which could affect their fitness. In this study, the factors determining the time of oviposition and the consequences it has for clutch size and juvenile survival were investigated in the orb-web spider Argiope bruennichi. Egg-sacs laid at different times in the field were collected and inspected for eggs, hatching success and presence of parasites. Relationships between spider body condition, clutch size and time of oviposition were established. The influence of supplementary food on the number of eggs in a clutch and on the time of oviposition was determined both in the field and laboratory. Early clutches were larger and the eggs in late clutches were not heavier than those in early clutches indicating that spiders invested more in eggs at the beginning of the reproductive period. Furthermore, eggs in late egg-sacs were less likely to hatch and more likely to be parasitized. Clutch size was linked to spider body condition but not the time of oviposition. In the field, additional food to females resulted in larger clutches but did not influence the time of oviposition. Laboratory experiments showed that the daily rate of prey consumption affected egg oviposition.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
68984. Time of VO2max plateau and post-exercise oxygen consumption during incremental exercise testing in young mountain bike and road cyclists
- Creator:
- Hebisz, P, Hebisz, R, Borkowski, J, and Zatoń, M
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- cyklistika, fyziologie, cycling, physiology, time of maximal oxygen plateau, anaerobic metabolism, 14, and 612
- Language:
- English
- Description:
- The purpose of this study was to compare markers of glycolytic metabolism in response to the Wingate test and the incremental test in road and mountain bike cyclists, who not different performance level and aerobic capacity. All cyclists executed the Wingate test and incremental test on a cycle ergometer. Maximal power and average power were determined during the Wingate test. During the incremental test the load was increased by 50 W every 3 min, until volitional exhaustion and maximal aerobic power (APmax), maximal oxygen uptake (VO2max), and time of VO2max plateau (Tplateau) were determined. Post-exercise measures of oxygen uptake (VO2post), carbon dioxide excretion, (VCO2post), and the ratio between VCO2/VO2 (RERpost) were collected for 3 min immediately after incremental test completion. Arterialized capillary blood was drawn to measure lactate (La-) and hydrogen (H+) ion concentrations in 3 min after each test. The data demonstrated significant differences between mountain bike and road cyclists for Tplateau, VO2post, VCO2post, La- which was higher-, and RERpost which was lower-, in mountain bike cyclists compare with road cyclists. No differences were observed between mountain bike and road cyclists for APmax, VO2max, H+ and parameters measured in the Wingate test. Increased time of VO2max plateau concomitant to larger post-exercise La- and VO2 values suggests greater anaerobic contribution during incremental testing efforts by mountain bike cyclists compared with road cyclists., P. Hebisz, R. Hebisz, J. Borkowski, M. Zatoń., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
68985. Time sensitivity and acceptance of testimony
- Creator:
- Alsamaani, Nader
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- acceptance of testimony, time sensitivity, reductionism, and non-reductionism
- Language:
- Slovak
- Description:
- Time sensitivity seems to affect our intuitive evaluation of the reasonable risk of fallibility in testimonies. All things being equal, we tend to be less demanding in accepting time sensitive testimonies as opposed to time insensitive testimonies. This paper considers this intuitive response to testimonies as a strategy of acceptance. It argues that the intuitive strategy, which takes time sensitivity into account, is epistemically superior to two adjacent strategies that do not: the undemanding strategy adopted by non-reductionists and the cautious strategy adopted by reductionists. The paper demonstrates that in adopting the intuitive strategy of acceptance, one is likely to form more true beliefs and fewer false beliefs. Also, in following the intuitive strategy, the listener will be fulfilling his epistemic duties more efficiently.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
68986. Time series analysis of hydrologic data for water resources planning and management: a review
- Creator:
- Machiwal, Deepesh and Jha, Madan K.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- time series analysis techniques, review, climatologic time series, hydrologic time series, water resources planning and management, techniky analýzy časových radov, prehľad, časové rady v hydrológii, časové rady v klimatológii, vodohospodárske plánovanie, and riadenie vodného hospodárstva
- Language:
- Slovak
- Description:
- The main intent of this paper is to present a review on the application of time series analysis techniques in hydrology and climatology. An overview of various statistical tests for detecting and estimating the hydrologic time series characteristics (i.e., homogeneity, stationarity, trend, periodicity, and persistence) is presented, together with their merits and demerits followed by comprehensive reviews of past studies (both basic and applied), and future research directions. The present review revealed that the climatologic time series of precipitation, air temperature, evapotranspiration and climatic change, and the hydrologic time series of streamflow and surface water quality have received a great deal of attention worldwide. Although the application areas of time series analysis techniques are expanding with growing concerns about climate change and global warming, their application is still very limited in groundwater hydrology as well as for non-traditional hydrologic time series. It is also apparent from this review that the detection of trend and stationarity by parametric and/or nonparametric tests has been a major focus in the past. Multiple comparison tests lack appreciation by the researchers for testing homogeneity in the hydrologic and climatologic time series. Furthermore, most studies have ignored the importance of testing periodicity and persistence in the time series, which are equally important properties of hydrologic and climatologic time series. Based on the comprehensive review, future research needs for time series studies in hydrology and climatology are discussed. and Príspevok prináša prehľad aplikácií techník analýzy časových radov v hydrológii a klimatológii. Uvádza prehľad rôznych štatistických testov na zistenie charakteristík týchto radov (napr. homogenity, stacionarity, trendov, periodicity a perzistencie), spolu s ich prednosťami a nedostatkami. Ďalej je uvedený tiež celkový prehľad uskutočnených štúdií (základných aj aplikovaných) a smery výskumu pre budúcnosť. Súčasný prehľad naznačuje celosvetové sústredenie pozornosti na časové súbory klimatologických dát zrážok, teploty vzduchu, evapotranspirácie a zmien klímy, a tiež hydrologických dát prietokov a kvality povrchových vôd. Aj keď so zvýšením záujmu o zmenu klímy a globálne otepľovanie sa oblasti použitia techník analýzy časových radov rozširujú, ich aplikácie v oblasti hydrológie podzemných vôd a ďalších nie celkom tradičných hydrologických údajov sú veľmi obmedzené. Tento prehľad tiež uvádza, že v minulosti sa vyskytli snahy o sústredenie úsilia na postihnutie trendov a stacionarity radov použitím parametrických a/alebo neparametrických testov. Mnohí výskumníci dostatočne neoceňujú viacnásobné porovnávacie testy (multiple comparison tests) homogenity hydrologických a klimatických časových radov. Okrem toho vo väčšine štúdií sú zanedbané dôležité testy periodicity a perzistencie hydrologických radov. Tieto sú ich rovnako dôležité charakteristiky. Na základe všeobecného prehľadu príspevok tiež pojednáva o potrebe ďalšieho výskumu časových radov v hydrológii a klimatológii.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
68987. Time series prediction by parallel feedforward process neural network with time-varied input and output
- Creator:
- Gang , Ding and Shisheng, Zhong
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Parallel feedforward process neural network (PFPNN), time series, orthogonal basis function, aircraft engine condition monitoring, and learning algorithm
- Language:
- English
- Description:
- Time series prediction plays an important role in engineering applications. Artificial neural networks seem to be a useful tool to solve these problems. However, in real engineering, the inputs and outputs of many complicated systems are time-varied functions. Conventional artificial neural networks are not suitable to predicting time series in these systems directly. In order to overcome this limitation, a parallel feedforward process neural network (PFPNN) is proposed. The inputs and outputs of the PFPNN are time-varied functions, which makes it possible to predict time series directly. A corresponding learning algorithm for the PFPNN is developed. To simplify this learning algorithm, appropriate orthogonal basis functions are selected to expand the input functions, output functions and network weight functions. The effectiveness of the PFPNN and its learning algorithm is proved by the Mackey-Glass time series prediction. Finally, the PFPNN is utilized to predict exhaust gas temperature time series in aircraft engine condition monitoring, and the simulation test results also indicate that the PFPNN has a faster convergence speed and higher accuracy than the same scale multilayer feedforward process neural network.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
68988. Time series prediction using convolution sum discrete process neural network
- Creator:
- Gang, Ding, Da, Lei, and Shisheng, Zhong
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Process neural network, functional approximation, time series prediction, aeroengine health condition, and monitoring
- Language:
- English
- Description:
- A convolution sum discrete process neural network (CSDPNN) is proposed. CSDPNN utilizes discrete samples as inputs directly and employs convolution sum to simulate the process inputs so as to deal with the time accumulation existing in many time series. Without the procedures of fitting the discrete samples into continuous functions to generate inputs and then to expand the input functions by basis functions, CSDPNN is better understandable and is with less precision reduction compared with process neural network (PNN) with function inputs. The approximation capacity of CSDPNN is analyzed in this paper, and it proved that CSDPNN can approximate PNN and has approximation capacity not worse than traditional artificial neural network (ANN). Finally, CSDPNN, PNN and ANN are utilized to predict the Logistic chaos time series and the iron concentration in the lubrication oil of aircraft engine, and the application test results indicate that CSDPNN performs better than PNN and ANN given the same conditions.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
68989. Time transfer using optical fiber links
- Creator:
- Kuna, Alexander and Smotlacha, Vladimír
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- time, frequency, time transfer, optical fiber, optical network, čas, frekvence, časový transfer, optické vlákno, and optická síť
- Language:
- Czech
- Description:
- This paper describes our experience with time transfer using optical fibers and fully optical networks. We developed a technique and instrumentation for the comparison of distant time scales. These were first verified using a 740km optical loop within the Czech NREN backbone network and later a long term two-way optical time transfer between Czech and Austrian national time and frequency laboratories where the maintaining of their national time and frequency standards was evaluated. The optical link utilizes either dedicated optical fibers or Dense Wavelength Division Multiplex (DWDM) channels in all-optical production telecommunication networks. Results from the optical transfer, i.e. clock comparison and link delay including diurnal and seasonal effects are shown and also compared with a traditional time transfer using signals from the satellite navigation systems. and Článek popisuje naše dlouhodobé zkušenosti s časovým transferem prostřednictvím optických vláken a plně optických sítí. Pro porovnávání časových stupnic na velkou vzdálenost jsme proto vytvořili techniku a vyvinuli potřebné přístrojové vybavení, které jsme nejprve ověřili pomocí optické smyčky v délce 744 km v rámci páteřní sítě CESNET a posléze také využili pro dvoucestný optický transfer mezi českou a rakouskou národní laboratoří, které jsou zodpovědné za vytváření národních časových stupnic v České republice a Rakousku. Optickou trasu tvoří temná vlákna nebo vyhrazené kanály ve vlnovém multiplexu DWDM. Článek uvádí dosažené výsledky časového transferu, včetně měření zpoždění signálu na trase, a tyto jsou rovněž srovnány s obecně používaným časovým transferem prostřednictvím satelitních navigačních systémů.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
68990. Time-course of photosynthetic induction in four tropical woody species grown in contrasting irradiance habitats
- Creator:
- Portes, M. T., Alves, T. H., and Souza, G. M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Bauhinia, Esenbeckia, Guazuma, Hymenaea, intercellular CO2 concentration, plant eco-physiology, respiration rate, stomatal conductance, sunfleck utilization, and tropical forest succession
- Language:
- Multiple languages
- Description:
- We investigated the photosynthetic induction time-course in species of different ecological groups grown in contrasting forest irradiance environments, gap and understorey, exposed to different darkness times in order to verify the plant capacity to exploit irradiance heterogeneity. Photosynthetic induction was studied in leaves of Bauhinia forficata and Guazuma ulmifolia (early succession species, ES), and Esenbeckia leiocarpa and Hymenaea courbaril (late succession species, LS). T50 and T90 (time estimates to attain 50 and 90 % of maximum net photosynthetic rate, respectively) varied according to the time of previous exposure to darkness and growth irradiance. In both darkness times of 10 and 30 min, T50 was lower in the LS-than ES-species. These results, jointly with significant higher induction state of the leaves after 10 min of darkness, suggest that the LS-species has a higher potential to sunfleck utilization compared to ES-species, both grown in the understorey. After 10 and 30 min of darkness the differences between ecological groups were not clearly detected in the gap for T50 and T90, indicating that eco-physiological characteristics of each ecological group did not influence the induction time of the species evaluated herein. Thus the capacity to show phenotypic plasticity is not exclusive to an ecological group, but it is rather a more intrinsic feature related to the differential capacity of individuals. and M. T. Portes, T. H. Alves, G. M. Souza.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public