Romanian policy makers have to perceive that human intervention on river basins land cover is influencing rainfall-runoff relation and the used methodology cannot accurately estimate watershed surface flow transformations. Global water cycles and energy fluxes understanding is leading to better predictions of land atmosphere interaction and local hydro-climates evolution. The water transfer time determination from rainfall to runoff needs accurate measurements of river basins hydrological parameters. Here, we analyzed and compared the lag time value results of two different methodologies (curve number and rational methodology) used for 54 Romanian small catchment areas study. The focus of this paper is the lag time evaluation and interpretation for an effective implementation of the best methodology approach in the Romanian geographical space. Our research in small river basins was developed using remote sensing technology maps, GIS and environmental datasets in combination with field work on every drainage basin in order to assess the specific morphological features and validate the land cover typology. We found that Soil Conservation Service - Curve Number (SCS-CN) method is widely used according to USA landscape features classification, but not necessarily applicable to Romanian river basins characteristics. Our results show how the official Romanian rational methodology national standard (RNS) can be improved and the limits of SCS-CN method.
Multiwalled carbon nanotubes have been produced from H2-C2H4 mixtures on Fe-SiO2 catalysts by a fluidized bed catalytic chemical vapor deposition process. Various parameters such as the catalyst preparation, the residence time, the run duration, the temperature, the H2:C2H4 ratio, the amount of metal deposited on the support have been examined. The influence of these parameters on the deposited carbon yield is reported, together with observations of the produced material. This process allows an homogeneously distributed deposition of nanotubes (10-20 nm diameter), that remain anchored to the support. 相似文献
An ultrasonic technique was developed to study the crystallization process of edible fats on-line. A chirp wave was used instead
of the conventional pulser signal, thus achieving a higher signal-to-noise ratio. This enabled measurements to be made in
concentrated systems [≈20% solid fat content (SFC)] through a 8.11-cm thick sample without significant signal loss. Fat samples
were crystallized at 20, 25, and 30°C at a constant agitation rate of 400 rpm for 90 min. The crystallization process was
followed by ultrasonic spectroscopy and a low-resolution pulsed nuclear magnetic resonance spectrometer. Specific relationships
were found between ultrasonic parameters [integrated response, time of flight (TF), and full width half maximum] and SFC.
TF, which is an indirect measurement of the ultrasonic velocity (v), was highly correlated to SFC (r2>0.9) in a linear fashion (v=2.601 SFC+1433.0). 相似文献
State feedback control is very attractive due to the precise computation of the gain matrix, but the implementation of a state feedback controller is possible only when all state variables are directly measurable. This condition is almost impossible to accomplish due to the excess number of required sensors or unavailability of states for measurement in most of the practical situations. Hence, the need for an estimator or observer is obvious to estimate all the state variables by observing the input and the output of the controlled system. As such, the goal of this paper is to provide a control design methodology based on a Luenberger observer design that can assure the closed-loop performances of a vehicle drivetrain with backlash, while compensating the network-enhanced time-varying delays. This goal is achieved in a sequential manner: firstly, a piecewise linear model of two inertias drivetrain, which takes into consideration the backlash nonlinearity and the network-enhanced time-varying delay effects is derived; then, a Luenberger observer which estimates the state variables is synthesized and the robust full state-feedback predictive controller based on flexible control Lyapunov functions is designed to explicitly take into account the bounds of the disturbances caused by time-varying delays and to guarantee also the input-to-state stability of the system in a non-conservative way. The full state-feedback predictive control strategy based on the Luenberger observer design was experimentally tested on a vehicle drivetrain emulator controlled through controller area network, with the aim of minimizing the backlash effects while compensating the network-enhanced delays. 相似文献
A large-scale, multi-year, randomized study compared learning activities and outcomes for hands-on, remotely-operated, and simulation-based educational laboratories in an undergraduate engineering course. Students (N = 458) worked in small-group lab teams to perform two experiments involving stress on a cantilever beam. Each team conducted the experiments in one of three lab formats (hands-on, remotely-operated, or simulation-based), collecting data either individually or as a team. Lab format and data-collection mode showed an interaction, such that for the hands-on lab format learning outcomes were higher when the lab team collected data sets working as a group rather than individually collecting data sets to be combined later, while for remotely-operated labs individual data collection was best. The pattern of time spent on various lab-related activities suggests that working with real instead of simulated data may induce higher levels of motivation. The results also suggest that learning with computer-mediated technologies can be improved by careful design and coordination of group and individual activities. 相似文献
The systemic inflammatory syndrome concept is one of the foundations that stand at the basis of revolutionary modern and future therapies, based on the in-depth understanding of the delicate mechanisms that govern the collaboration between the systems and organs of the human body and, at the same time, the fine balance that ensures a reproach-free operation. An interesting concept that we propose is that of the environment-inadequacy status, a concept that non-specifically incorporates all the situations of the organism’s response disorders in the face of imprecisely defined situations of the environment. The correlation between these two concepts will define the future of modern medicine, along with the gene-adjustment mechanisms. Psoriasis is a clear example of an inadequate body response as a result of exposure to as of yet undefined triggers with an excessive systemic inflammatory reaction and hitherto insufficiently controllable. Modern biological therapies, such as TNF-α, IL-12 family, and IL-17 inhibitors, are intended to profoundly reshape the cytokine configuration of patients with inflammatory diseases such as psoriasis, with tremendous success in disease control. Yet, because of the important roles of cytokines in cancer promotion and control, concern was raised about the fact that the use of biologicals may alter immune surveillance and promote cancer progression. Both theoretical and practical data nevertheless showed that the treatment-induced control of cytokines may be beneficial for reducing the inflammatory milieu that promotes cancer and such have a beneficial role in maintaining health. We briefly present the intricate roles of those cytokine families on cancer control, with some debates on if their inhibition might or might not promote additional tumoral development. 相似文献
A new diol with azoaromatic pendant was prepared by N-phenyl-4-amido-3,4-dichloromaleimide with 2-mercaptoethanol in the presence of NaOH, and used to obtain photosensible poly(urethane-urea)
varnish. A poly(urethane-urea) varnish bearing azobenzene chromophores, based on a poly(ethylene adipate)diol (average molecular
weight—2000), 4,4′-dibenzyldiisocyanate, diethylene glycol, trimethylolpropane, and afore-mentioned diol, were prepared and
characterized. The polymers were characterized by FTIR spectroscopy, thermal analysis (DMA, DSC, and TGA), and the photochromic
behavior by UV irradiation of thin films was discussed. 相似文献
This work continued our general research program on obtaining metallic cerium by electrodeposition from NaCeF4 dis-solved in different molten fluorides. The structure of NaCeF4 (cubic or hexagonal depe... 相似文献