In this research a novel low power multi-mode continuous time Delta Sigma modulator was designed to be compatible with many mobile wireless standards. This modulator has a reconfigurable structure to adapt to various standards from 0.2 to 20 MHz. The designed modulator uses a VCO-based quantizer not only for lowering power consumption, but also for reducing the required chip area. The presented modulator can function with up to third order of noise shaping, or in a low power mode in which the loop filter is disabled and only the VCO-based quantizer is used. The proposed modulator was implemented and simulated in transistor level in 180 nm technology. This modulator can digitize at least seven standards (LTE (20 MHz)/WLAN/LTE (9 MHz)/WCDMA/UMTS/Bluetooth/GSM) with a favorable dynamic range (65–89 dB) and power consumption (9.1 mW–670 μW). 相似文献
Absorption and scattering properties of product change as moisture content is reduced, but it has not been investigated how these changes are correlated. This study was aimed to measure and test the feasibility of using optical properties in predicting the moisture content of sliced apple samples during hot air drying. In this investigation, the noninvasive backscattering laser imaging technique at three wavelengths (650, 780, and 880?nm) and Farrell’s diffusion theory were used to determine absorption and reduced scattering coefficients. Artificial neural network model was applied to correlate the optical coefficients and moisture content of samples. The highest correlation between above-mentioned parameters was found at 780?nm. The best moisture content prediction result was obtained when absorption and reduced scattering coefficients were combined at three wavelengths with Rp?=?0.984. The results suggested that this method can be effectively used to predict the moisture content and control the drying process. 相似文献
Journal of Central South University - Squeezing ground in tunneling is associated with large deformation of the tunnel face. In this study, squeezing characteristics of the ground and rock... 相似文献
The influence of dietary vitamin E supplementation on the α-tocopherol content of muscle membranes and on the resultant oxidative stability of veal was investigated. Daily supplementation of veal calves with 500 mg vitamin E in the form of α-tocopherol acetate for 12 weeks after birth increased muscle and membranal α-tocopherol concentrations approximately 6-fold over those of control animals. Oxidative stability of mitochondrial and microsomal lipids was enhanced by dietary supplementation as indicated by the results of an oxidative assay using hydrogen peroxide-activated metmyoglobin as the catalyst of oxidation. Muscle lipid and cholesterol stability was also improved by supplementation. 相似文献
A novel phenomenological discrete bubble model was developed and tested for prediction of the hydrodynamic behavior of the dense phase of a 3D gas‐solid cylindrical fluidized bed. The mirror image technique was applied to take into account the effects of the bed wall. The simulation results were validated against experimental data reported in the literature that were obtained by positron emission particle tracking. The time‐averaged velocity profiles of particles predicted by the developed model were found to agree well with experimental data. The initial bubble diameter had no significant influence on the time‐averaged circulating pattern of solids in the bed. The model predictions clearly indicate that the developed model can fairly predict the hydrodynamic behavior of the dense phase of 3D gas‐solid cylindrical fluidized beds. 相似文献
The present study aims at assessing the hydrochemistry of the groundwater system of the Maragheh-Bonab Plain located in the East Azarbaijan Province, northwest of Iran. The groundwater is used mainly for drinking, agriculture and industry. The study also discusses the issue of the industrial untreated wastewater discharge to the Plain aquifer that is a high Ca-Cl water type with TDS value of about 150 g/L. The hydrogeochemical study is conducted by collecting and analyzing the groundwater samples from July and September of 2013. The studied system contains three major groundwater types, namely Ca–Mg–HCO3, Na–Cl, and non-dominant water, based on the analysis of the major ions. The main processes contributing to chemical compositions in the groundwater are the dissolution along the flow path, dedolomitisation, ion exchange reactions, and the mixing with wastewater. According to the computed water quality index (WQI) ranging from 25.45 to 194.35, the groundwater in the plain can be categorized into “excellent water”, “good water”, and “poor water”. There is a resemblance between the spatial distribution of the WQI and hydrochemical water types in the Piper diagram. The “excellent” quality water broadly coincides with the Ca-Mg-HCO3 water type. The “poor” water matches with the Na–Cl water type, and the “good” quality water coincides with blended water. The results indicate that this aquifer suffers from intense human activities which are forcing the aquifer into a critical condition. 相似文献
The quality of topographic datasets plays a key role in deriving terrain model and hydraulic simulation. In developing countries, data-sparse regions and most parts of the world, accessing to high-quality datasets is almost impossible and topographic maps with a specific scale should be used to derive the geometry of river bed and floodplains. For these areas, understanding the effects of map scale on the costs of land surveying/river projects and flood inundation mapping may lead to an appropriate flood modeling and reduce huge amounts of financial resources. This research addresses the effect of using topographic maps with different scales on the hydraulic properties and focuses on using the relationship between topographic map scale, the costs of land surveying and hydraulic properties. The results from the three river reaches (SojasRood and SafaRood rivers in Zanjan and Mazandaran provinces, respectively and Sarbaz river in Sistan-Baluchistan province, Iran) used in this study show that in small-scale rivers (SojasRood and SafaRood rivers), the effect of topographic map’s scale on water surface elevation (WSE) isn’t meaningful up to 1:4000 (4 K) map scale, while in the case of Sarbaz river WSE is approximately scale independent (even up to 1:10000 (10 K) map) and there is no considerable discrepancy between low and high-quality maps in predicting this important variable. For example, in SojasRood river the mean absolute error (MAE) in simulation of WSE for low-quality maps (5 K and 6 K maps) varies between 0.79 m and 1.78 m, while for high-quality maps (1 K, 2 K and 3 K) it restricts to only 0.25 m. Also, in the case of Sarbaz river, for maps with the scale of higher than 5 K (high resolution maps) the maximum values of MAE and RMSE statistics limit to 0.13 m and 0.16 m, respectively. Moreover, findings demonstrate that using the topographic maps with the scales of 2 K and 7 K instead of high quality maps (1 K and 2 K maps in small-scale rivers and Sarbaz river, respectively as base maps) lead to the same geometric model and the mean relative error (MRE) in simulating inundation extents is lower than 10%. These outcomes clearly indicate that by accepting some reasonable errors the low quality maps, that are cost-effective and not time-consuming, can be considered as alternative maps for flood simulation in low budget projects. Furthermore, assessing the costs of ground surveying shows that it highly depends on the scale of topographic maps and by using low quality instead of high quality maps the costs of topographic maps’ production significantly decreases. In addition, changes in hydraulic properties due to using these maps are not considerable when compared to the significant saved financial resources.
Electricity has a significant role in the sustainable development of societies. Traditional methods of generating electricity face several challenges. The ever-increasing demand for electricity generation on the one hand, and the lack of adequate resources for fossil fuels on the other, has led to the use of renewable energy. Biomass is a renewable energy supply that can be used in electricity generation for a sustainable environment. This study aims to introduce a multi-criteria decision-making framework which integrates a geographical information system with a fuzzy analytic network process together with weighted linear combination to optimize the location of a biomass power plant in Guilan Province, Iran. For this purpose, the environmental and socioeconomic factors were identified, and the main contributing criteria were selected. The results showed that about 27.73 and 41.06% of the region has high or moderate suitability, respectively, for constructing a biomass power plant. In addition, a sensitivity analysis was performed to investigate the robustness of the outcomes of decision making by changing the weighting of the criteria. Results indicated that the ranking of alternative locations is independent of the weights chosen. 相似文献
Silicon - Carbon and their compounds were removed successfully through electron beam melting (EBM), so that those areas (contaminated with carbon) of ingot were recycled and reused. During EBM... 相似文献