Under- versus Overestimation of Aquifer Hydraulic Conductivity from Slug Tests

Groundwater Hydrology, Irrigatio

Finite Element Analysis on a Square Canister Piezoelectric Energy Harvester in Asphalt Pavement

Abstrac

Rigidity theorems of spacelike entire self-shrinking graphs in the pseudo-Euclidean space

In this paper, we firstly establish a new volume growth estimate for spacelike entire graphs in the pseudo-Euclidean space $\mathbb{R}^{m+n}_n$. Then by using this volume growth estimate and the Co-Area formula, we prove various rigidity results for spacelike entire self-shrinking graphs

Influence of structure on the optical limiting properties of nanotubes

We investigate the role of carbon nanotubes structure on their optical limiting properties. Samples of different and well-characterized structural features are studied by optical limiting and pump-probe experiments. The influence of the diameter's size on the nano-object is demonstrated. Indeed, both nucleation and growth of gas bubbles are expected to be sensitive to diameter

Wet steam flow and condensation loss in turbine blade cascades

This study develops a wet steam modelling to solve the phase change process inside the blade cascade of a steam turbine. The comparative study is carried out to understand the impact of the dry gas model and wet steam model on predicting the flow behaviours in a steam turbine. The effect of the cutback of the trailing edge on the flow structure and nonequilibrium condensation is evaluated in blade cascades. The results show that the dry gas assumption without considering the phase change process predicts fraudulently flow separations near the trailing edge to induce oblique waves. The maximum liquid fraction can reach approximately 0.051 based on the wet steam flow modelling. The condensation-evaporation processes in the blade cascades cause a condensation loss of 0.118 MW. The stronger expansion flow is obtained to induce the earlier onset of the homogeneous nucleation process with an increasing cutback of the trailing edge. The 21% cutback of the trailing edge leads to strong flow separations on the suction side to severely deteriorate the flow condition in blade cascades. It suggests that the cutback of the trailing edge by 14% is acceptable to repair damaged blades considering the flow structure, nonequilibrium phase change and condensation loss

Prediction of dehydration performance of supersonic separator based on a multi-fluid model with heterogeneous condensation

Supersonic separation is a novel technology. A multi-fluid slip model for swirling flow with homogenous/heterogenous condensation and evaporation processes in the supersonic separator was built to estimate the separation efficiency. This model solves the governing equations of compressible turbulent gas phase and dispersed homogenous/heterogenous liquid phase considering droplet coalescence and interphase force. Its prediction accuracy for condensation and swirling flows was validated. Then, the flow field, slip velocity and droplet trajectory inside the separators with different swirl strengths were investigated. The maximum values of radial slip velocity are 29.2 and 8.26 m/s for inlet foreign droplet radius of 1.0 and 0.4 micron. It means the larger foreign droplet has a better condensation rate. However, the residence time of larger foreign droplet in core flow is shorten. Thus, the inlet radius of foreign droplet has to be moderate for best separation efficiency. Finally, the dehydration performances of separator were evaluated. The optimal radius of inlet foreign droplet to maximize the dehumidification and efficiency was found. For the separator with swirl strength of 22%, the optimal radius is 0.85 micron at inlet pressure of 250 kPa, where the maximum dew point depression is 42.41 °C and the water removal rate is 87.82%

Changes in impervious surface area, flood frequency, and water chemistry within the Delaware River basin during the past 50 years: initial results

Proceedings of the Seventh International Conference on Hydroscience and Engineering, Philadelphia, PA, September 2006. http://hdl.handle.net/1860/732Housing development and total road mileage expansion, which result from the growing population and economic activity in the region, increased the total impervious surface area (ISA) within the Delaware River Basin (DRB) from either 3.19% or 3.69% of the total basin area in 1950 to either 5.41% or 6.44% of the total basin area in 2000, depending on which of two plausible scenarios are used for interpreting the available housing and road mileage data. Assuming an average area of 0.3 acre and 35% ISA for a single-unit detached house and 0.1 acre and 60% ISA for all other housing units, the projected ISA for the DRB is 5.66% in 2006. This result is comparable with the existing GIS data from the LandSat Thematic Mapper Imager for part of the DRB. Associated with the increasing ISA in the DRB, there also is an increase in flood events for recent years. Increased peak flows in July and August, which are the two months with the highest precipitation, also are noticeable. Concentrations of sodium and chloride in the Delaware River water increased between 2-4.6 times over the last 50 years at both upstream and downstream locations. Increased application of sodium chloride, in the form of deicing salt that is tied to the expansion of total road mileage in the basin, may be one of the main reasons for the increase of these ions in the waters of the Delaware River

Polydispersed droplet spectrum and exergy analysis in wet steam flows using method of moments

In steam turbine flow, the complex droplet spectrum caused by nonequilibrium condensation is necessary to be modeled accurately to predict the droplet behavior and estimate the exergy destruction and erosion rate. This study built and validated a polydispersed model with Quadrature method of moments (QMOM), consisting of transition SST model, the moments and entropy generation. A spline-based algorithm was used to reconstruct the shape of the probability density function (PDF) of radius. It’s proved that the polydispersed model has a better prediction result for Sauter radius compare with monodispersed model. Then, the distributions of moments and droplet spectra in the nozzle with effects of asymmetric lambda shock and evaporation were investigated. The shape of droplet spectrum is closer to gamma distribution in nucleation zone and log-normal distribution in growth zone when outflow is supersonic. In the turbine, because the oblique shock induces complex evaporation and secondary condensation, the reconstructed shape is closer to gamma distribution. Finally, the obtained maximum exergy destruction is 25.293 kJ/kg. The rate of exergy destruction increases from 1.04% to 4.45%. The range of Baumann factor is 0.574–1.312. Besides, the erosion rate in polydispersed model is only 58.4–64.3% of monodispersed model. The polydispersed model used in this study can predict the droplet spectrum and energy loss of the turbine systems more accurately

An edge cloud and Fibonacci-Diffie-Hellman encryption scheme for secure printer data transmission

Network printers face increasing security threats from network attacks that can lead to sensitive information leakage and data tampering. To address these risks, we propose a novel Fibonacci-Diffie-Hellman (FIB-DH) encryption scheme using edge cloud collaboration. Our approach utilizes properties of third-order Fibonacci matrices combined with the Diffie-Hellman key exchange to encrypt printer data transmissions. The encrypted data is transmitted via edge cloud servers and verified by the receiver using inverse Fibonacci transforms. Our experiments demonstrate that the FIB-DH scheme can effectively improve printer data transmission security against common attacks compared to conventional methods. The results show reduced vulnerabilities to leakage and tampering attacks in our approach. This work provides an innovative application of cryptographic techniques to strengthen security for network printer communications