Influence of the ER,CR:YSGG laser and different irrigation methods on push-out bond strength of fiber post

Er,Cr:YSGG lasers are currently being investigated for disinfecting the root canal treatment. The aim of this study was to compare the effects of various irrigation protocols on push-out bond strength of fiber posts. Fifty maxillary anterior teeth were divided into five groups (n = 10) according to the protocol that applied into the post space. Group-1: distilled water, Group-2: 5% NaOCl, Group-3: 2% CHX, Group-4: Er,Cr:YSGG laser (1.5 W, 20 Hz, 85 air, 75 water, 26.7 J/cm²), Group-5: Er,Cr:YSGG laser (1.25 W, 50 Hz, 34 air, 24 water, 12.7 J/cm²). Fiber posts were cemented with resin cement. The remaining part of the root, three slices were obtained from each specimen and push-out test was performed. One-way ANOVA and Duncan’s test at a 5% level of significance were used for the statistical analysis. Post space irradiation with Er,Cr:YSGG laser (1.5 W 20 Hz, 85 air, 75 water, 26.7 J/cm²) increases push-out bond strength of fiber post to root canal dentin. Further investigations are needed to establish and optimize ER,Cr:YSGG laser parameters to increase the push-out bond strength of fiber posts.     

Measured and simulated flow downstream of the submerged sluice gate

In this study, turbulent flow downstream of the submerged sluice gate was investigated experimentally and numerically. Experimental studies were conducted in a laboratory flume to measure the flow velocities and turbulence characteristics. Three‐dimensional computational fluid dynamics (CFD) simulation was performed to investigate the flow structure downstream of the sluice gate. It is found that the flow downstream of the submerged sluice gate is highly three‐dimensional and unsteady in nature because of the interaction of mean flow and recirculation flow. The three‐dimensional simulation results indicate that the interacted flow triggers the formation of two corner vortices. Secondary velocities associated with the free surface vortices are found to be about 6% of the mean jet velocity at the inlet, which is significant for the river bank erosion. Vortex induced free surface fluctuations were also observed in the vicinity of the submerged gate.     

稻草制浆造纸废水灌溉对芦苇生长影响的研究

通过稻草制浆造纸废水灌溉桶栽芦苇的试验,芦苇生长良好,增产效果显著.芦苇对造纸废水的适应能力较强,COD.达4000mg/L的废水也可用于灌溉,但采用地下茎移栽的,初期宜用清水灌溉,2个月后再实行污水灌溉.     

Nonuniform and Unsteady Solute Transport in Furrow Irrigation. II: Description of Field Experiments and Calibration of Infiltration and Roughness Coefficients

Field tests were conducted to obtain irrigation evaluation and solute transport data. The data were used to calibrate and validate an advection-dispersion model for furrow irrigation. The empirical infiltration equation and roughness parameters were estimated from the evaluation data. The inflow rate was measured with a volumetric meter and a flume and resulted in different average inflow rates. Hydraulic simulation results proved nearly as accurate with infiltration function estimates derived from the meter or flume data despite the difference in measured flow rate. Hence, the calibrated infiltration functions provide limited clues about possible problems with the inflow data. The choice of the infiltration equation used to fit the data (Branch versus modified Kostiakov) produced greater differences in the hydraulic modeling results. The timing and spread of the solute concentration pulses were well predicted independently of the inflow data and infiltration equation used to fit the data. However, differences between the meter and flume inflow rate were clearly manifested in the predicted peak solute concentrations. Results highlight the importance of accurate inflow measurements for parameter estimation.     

Furrow Irrigation Advance Simulation Using a Surface–Subsurface Interaction Model

A model for the simulation of furrow irrigation advance was developed based on the Saint-Venant equations for the one-dimensional surface flow and the two-dimensional Richards equation for porous media flow. Solutions are computed numerically using finite differences for the surface flow and finite elements for the subsurface flow. Computations are internally coupled through an iterative procedure. Infiltration is computed with the Richards equation every five nodes used in the surface flow computations and by linear interpolation at the remaining nodes. In addition, the Richards equation is solved at the boundaries of the surface flow domain and in the vicinity of the wave front. The time step is calculated using the Courant–Friedrich–Lewy condition and a stability criterion that accounts for friction effects. This combined criterion prevents numerical instabilities and convergence problems, especially in cases of high friction coefficient, low discharge rates, and/or high infiltration rates resulting generally in low flow depth and slow irrigation advance. The model was evaluated against an approach involving high resolution correspondence used in both surface and subsurface flow, using different soil types, inflow discharge, and stability criteria.     

Compatibility Assessment of Drip Irrigation Laterals

Emitters inserted in drip irrigation laterals cause local head loss, generally estimated as a product of a coefficient and the velocity head. This local head loss coefficient and the emitter discharge curve hydraulic parameters may exhibit considerable variability attributable to the manufacturing process. This paper provides a framework for assessing whether the variability in the hydraulic parameters could lead to significant differences in the performance of rolls of drip irrigation laterals from the same manufacturing batch. A system approach with inlet pressure as input, pressure distribution along the drip lateral and inlet discharge as outputs (or responses), and a drip lateral hydraulic model as the transfer function is explored. Within a Bayesian statistical framework of parameter uncertainty based on the Metropolis algorithm, the hydraulic parameters of pressure-compensating drip lateral rolls from the same manufacturing batch were inferred (calibrated). Overlapping of the space (region) of the hydraulic parameters of different drip laterals give an indication of compatibility (similarity) of the drip laterals. Results indicated that half of the drip lateral rolls tested were strongly compatible, a third were weakly compatible, and the remainder were not compatible with any other. This finding has significant ramifications in the design of drip irrigation lateral networks. Therefore, it is essential to closely examine the hydraulic properties of drip laterals for the design of drip irrigation networks to avoid poor performance of the system.     

Conference news

Wetlands are often considered as “economically unproductive”. In this paper it is shown that for the African floodplains this unjustly denies the actual and potential benefits of the traditional land use systems. Both in terms of water use and financial costs traditional African floodplain exploitation compares very well with modern irrigation schemes. Gross earnings of irrigation systems must figure at least three times as much as traditional floodplain production in order to attain the same net margin of profit. This reflects the shadow‐price of the work done by nature.     

初探水文地质工程勘察在开发地源热泵中作用

开发地源热泵,利用地下水作为地源热泵的冷热源,需要进行专门的水文地质勘察,勘察重点要取得冷热源井的出水量、回灌量、地下水温度、水位、流速、流向和水质资料,选择理想的供水含水层,评估地下水可开采量,初步确定抽灌井比等,本文结合工程实例对地源热泵水文地质勘察需要解决的问题做初步的探讨,说明水文地质勘察在开发地源热泵中具有十分重要的意义。     

屋顶绿化节水技术措施的探讨

本文结合屋顶绿化的具体特点,探讨屋顶绿化的节水灌溉技术的选择和屋顶花园种植区构造层中的疏水层改进,对解决屋顶绿化灌溉与排水设计过程中常遇见的问题提出了合理的设计思路。     

洪临灌区渠道防渗及处理措施

因肃州区洪临灌区处于干旱地区的多种农业土壤中,灌区的水渠和农田水分渗漏损失较大,以致大量水分无效消耗且灌溉水利用率不高,也不利于农作物生长。因此提高灌区输水渠道的防渗性和改进灌区灌溉措施,不仅缓解干旱地区水资源不足的问题还可提高灌溉水利用率,针对灌区渠道情况提出一些防渗措施。