Transient Investigation of the Critical Abstraction Rates in Coastal Aquifers: Numerical and Experimental Study

This research investigated the transient saltwater upconing in response to pumping from a well in a laboratory-scale coastal aquifer. Laboratory experiments were completed in a 2D flow tank for a homogeneous aquifer where the time evolution of the saltwater wedge was analysed during the upconing and the receding phase. The SEAWAT code was used for validation purposes and to thereafter examine the sensitivity of the critical pumping rate and the critical time (the time needed for the saltwater to reach the well) to the well design and hydrogeological parameters. Results showed that the critical pumping rate and the critical time were more sensitive to the variations of the well location than the well depth. The critical time increased with increasing the location and depth ratios following a relatively linear equation. For all the configurations tested, the lowest critical pumping rate was found for the lower hydraulic conductivity, which reflects the vulnerability of low permeability aquifers to salinization of pumping wells. In addition, higher saltwater densities led to smaller critical pumping rate and shorter critical time. The influence of the saltwater density on the critical time was more significant for wells located farther away from the initial position of the interface. Moreover, increasing the dispersivity induced negligible effects on the critical pumping rate, but reduced the critical time for a fixed pumping rate.     

Analysis of the influence of diode reverse recovery on theoperation and design of high-frequency rectifiers

Diode reverse recovery can cause anomalies in high-frequency rectifier operation, including self-sustaining quasiperiodic oscillations. The output voltage can increase considerably beyond that predicted by the usual analysis. This nonlinear effect is analyzed using a piecewise-linear diode model. The theoretical results agree with experimental measurements. Design guidelines are presented to avoid overvoltage and instability in practical converters     

Concentration of solar radiation by white backed photovoltaic panels

In this paper, we present an analysis of the concentration achieved by white backed photovoltaic panels. Concentration is due to the trapping by light scattered in the refractive plate to which the solar cell is bonded. Using the reciprocity relation and assuming the ideal case of a Lambertian distribution, a detailed model is formulated that includes the effects of the thickness and walls of the concentrator. This model converges to the thermodynamic limit and is found to be consistent with experimental results for a wide range of cell sizes. Finally, the model is generalized to multiple-cell photovoltaic panels.     

粉末冶金连接方法、材料与工艺

本文将讨论在铁基粉末冶金材料与零件连接中最常用的各种连接方法。主要对以前发表的关于各种连接方法的资料与文献进行综述。列出了有用的设计资料及生产工艺,同时确认了各种粉末冶金材料组成的可焊性。     

Modelling the influence of inulin as a fat substitute in comminuted meat products on their physico-chemical characteristics and eating quality using a mixture design approach

The effects of fat substitution using two commercial inulin products on the physico-chemical properties and eating quality of a comminuted meat product (breakfast sausage) were modelled using a specialised response surface experiment specially developed for mixtures. 17 treatments were assigned representing a different substitution level for fat with inulin. Sausages were formulated to contain pork shoulder, back fat/inulin, water, rusk and seasoning (44.3, 18.7, 27.5, 7 and 2.5% w/w). Composition, sensory, instrumental texture and colour characteristics were assessed. Fructan analysis showed that inulin was unaffected by heat or processing treatments. Models showed increasing inulin inclusions decreased cook loss (p < 0.0017) and improved emulsion stability (p < 0.0001) but also resulted in greater textural and eating quality modification of sausages. Hardness values increased (p < 0.0001) with increasing inulin concentration, with panellists also scoring products containing inulin as less tender (p < 0.0112). Optimisation predicted two acceptable sausage formulations with significantly lower fat levels than the control, which would contain sufficient inulin to deliver a prebiotic health effect.     

A guide to safe corporotomy incisions in the presence of underlying inflatable penile cylinders: results of in vitro and in vivo studies

PURPOSE: Because iatrogenic injury to an underlying inflatable implant may be induced by electrocautery incision of the tunica during tunical release or cylinder reexploration, safe electrocautery guidelines are needed. MATERIALS AND METHODS: For the in vitro model silicone and polyurethane elastomer lined inflatable penile prosthetic cylinders were used, and cutting and coagulation electrocautery was applied directly on the device, on a tissue-implant interface, and at minimal, partial or full inflation with saline. For the in vivo study 10 patients with underlying inflatable prosthetic cylinders underwent tunical releases for treatment of secondary penile curvature (7) and reexploration for a malpositioned device (3) with a minimum 1 year of followup. RESULTS: In the in vitro study electrocautery injuries either did not occur when applied directly to silicone and polyurethane elastomer lined devices, occurred in both devices in the presence of a tissue-implant interface, occurred in polyurethane elastomer lined devices at a far less thermal energy setting than with silicone, occurred in both implants at lower wattages with increasing saline inflation or did not occur in 100% of polyurethane elastomer lined devices when coagulation electrocautery was less than 65 watts. In the in vivo study, by adhering to the aforementioned principles and using novel surgical techniques, no device malfunctions were created intraoperatively or observed within a mean followup of 22 months. CONCLUSIONS: Electrocautery can be used safely to create a tunical incision with any underlying inflatable cylinder. To avoid electrocautery injury, based on the clinical study results in polyurethane elastomer lined devices, one should deflate the cylinder before electrocautery, use coagulation current at 35 watts, apply the electrocautery only to the outer longitudinal tunical layer, bluntly dissect through the inner circular layer, and elevate the tunica, protect the device and incise the tissue under direct vision.     

Folding and stability of a fibronectin type III domain of human tenascin

An electrospray ionization-mass spectrometric procedure has been developed for determining glycohemoglobin. Whole-blood samples from 78 diabetic and 50 nondiabetic subjects (glycation range 3-15%, as determined by electrospray mass spectrometry) were diluted 500-fold in an acidic denaturing solvent and introduced directly into a mass spectrometer. The resulting mass spectra were then processed to estimate the percentage of glycohemoglobin present in the sample. Total analysis time, including plotting the spectra and computing the percentage of glycation, was approximately 3 min. The imprecision (CV) of the method was < 5.1% for inter- and intrabatch analyses for total glycohemoglobin in the range 3.6-14%. Comparison of the mass spectrometric results with those from established affinity chromatographic procedures showed good overall agreement. The relative glycation of the alpha- and beta-chains was determined directly and was shown to be constant (0.64:1) over the glycation range measured. Only single glucose attachment to both the alpha- and beta-chains was observed.