The square root method for chloride ingress prediction—Applicability and limitations

A recent observation showed a square root time dependency of the ingress depth of a fixed (reference) chloride concentration of 0.05% chloride by mass of concrete for submerged exposure in Kattegat and the Baltic Sea. The purpose of this paper is to assess the applicability and limitations of the observation, widen the scope of validity and propose it as a method. Field data from submerged, tidal, splash, atmospheric and inland deicing salt exposure at various geographical locations was analyzed at a range of reference concentrations. In total 237 combinations of concrete, exposure, and reference concentration were analyzed. Our results showed that chloride ingress of a reference concentration followed a linear relationship with an average R2 of 0.96, when the penetration depth of the reference concentration was plotted against the square root of the exposure time. The square root observation appeared valid for the studied Portland cement based concretes with fly ash, silica fume and ground granulated blast furnace slag exposed in submerged and tidal exposure zones, when applying reference concentrations of 0.1–1.8% chloride by mass of binder, and reference concentrations of 0.1–0.5% chloride by mass of binder in atmospheric exposure zone. It was found that the parameters describing the straight line depended on the chosen reference concentration and concrete composition, and that the slope of the straight line (ingress parameter) in addition depended on the exposure. It was concluded that the square root method appears to be a promising method for predicting further chloride ingress into concrete.

Quantitative Evaluation of Plant Priority Protection in Cao Lake Wetland Nature Reserve

Based on the survey data of plant resources in Cao Lake Wetland Nature Reserve, using analytic hierarchy process (AHP) and square root method, the evaluation system of plant priority protection was constructed. From three aspects of endangered coefficient, genetic coefficient and species coefficient, the plant species in the reserve were evaluated quantitatively and comprehensively, and the protection levels were divided. The results showed that there were 179 plant species in nature reserve, including 5 endangered species, 9 vulnerable species, 41 near threatened species and 124 least concerned species. The priority protection levels of plants were determined, including 1 species of the primary protection, 12 species of the secondary protection, 20 species of the tertiary protection and 146 species of the delayed protection, and corresponding protection suggestions were put forward. The purpose is to provide more effective background information and data support for the plant protection work and to help protect biodiversity.

Extending the Square Root Method to Account for Additive Forecast Noise in Ensemble Methods

A square root approach is considered for the problem of accounting for model noise in the forecast step of the ensemble Kalman filter (EnKF) and related algorithms. The primary aim is to replace the method of simulated, pseudo-random additive so as to eliminate the associated sampling errors. The core method is based on the analysis step of ensemble square root filters, and consists in the deterministic computation of a transform matrix. The theoretical advantages regarding dynamical consistency are surveyed, applying equally well to the square root method in the analysis step. A fundamental problem due to the limited size of the ensemble subspace is discussed, and novel solutions that complement the core method are suggested and studied. Benchmarks from twin experiments with simple, low-order dynamics indicate improved performance over standard approaches such as additive, simulated noise, and multiplicative inflation.

The DSP Design and Implementation of a Directional Audio System through N-Order Approximate Square Root Method

The signal preprocessing methods in a directional audio system are almost based on Berkatay far-field solution. In this paper, the basic principle and performance of square root method are analyzed, and also a directional audio system based on floating-point DSP is designed with the 4-order approximate square root method. Through theory simulation and practical test, the effect is proven to be satisfactory.