Performance Comparison of Four Fiber-Reinforced Polymer Deck Panels

In an effort to assess the constructability and performance of bridges with fiber-reinforced polymer (FRP) composite decks, the short-term and long-term responses of a 207 m, five-span bridge retrofitted with four different FRP panel systems were monitored. The overall aspects of the panel systems, connection details, and construction techniques are presented prior to presentation of the observed and measured responses. Key design parameters (impact factors, girder distribution factors, and level of composite action) for FRP and reinforced concrete decks are evaluated. This paper demonstrates that FRP replacement decks are a viable alternative to reinforced concrete decks and identifies the differences in performances of various FRP deck systems. Two of the FRP panel systems were found to perform considerably better than the other deck systems. Issues that may reduce the service life of FRP deck systems are presented and discussed.     

Exact solutions for vibration and buckling of an SS-C-SS-C rectangular plate loaded by linearly varying in-plane stresses

Exact solutions are presented for the free vibration and buckling of rectangular plates having two opposite edges (x=0 and a) simply supported and the other two (y=0 and b) clamped, with the simply supported edges subjected to a linearly varying normal stress σ_x=−N₀[1−α(y/b)]/h, where h is the plate thickness. By assuming the transverse displacement (w) to vary as sin(mπx/a), the governing partial differential equation of motion is reduced to an ordinary differential equation in y with variable coefficients, for which an exact solution is obtained as a power series (the method of Frobenius). Applying the clamped boundary conditions at y=0 and b yields the frequency determinant. Buckling loads arise as the frequencies approach zero. A careful study of the convergence of the power series is made. Buckling loads are determined for loading parameters α=0,0.5,1,1.5,2, for which α=2 is a pure in-plane bending moment. Comparisons are made with published buckling loads for α=0,1,2 obtained by the method of integration of the differential equation (α=0) or the method of energy (α=1,2). Novel results are presented for the free vibration frequencies of rectangular plates with aspect ratios a/b=0.5,1,2 subjected to three types of loadings (α=0,1,2), with load intensities N₀/N_cr=0,0.5,0.8,0.95,1, where N_cr is the critical buckling load of the plate. Contour plots of buckling and free vibration mode shapes are also shown.     

In vivo remineralization of acid-etched enamel in non-brushing areas as influenced by fluoridated orthodontic adhesive and toothpaste

This study aimed to evaluate the in vivo remineralization of acid-etched enamel in non-brushing areas as influenced by fluoridated orthodontic adhesive and toothpaste. One hundred and twenty teeth from 30 volunteers were selected. The teeth were assigned to four treatments: no treatment (negative control); 37% phosphoric acid-etching (PAE) (positive control); PAE + resin-modified glass ionomer cement (RMGIC); and, PAE + composite resin. Patients brushed teeth with fluoridated (n = 15) or non-fluoridated (n = 15) toothpastes, so that etched enamel was protected with screens and it was not in contact with the brush bristles. Remineralization was evaluated by means of laser fluorescence (LF), environmental scanning electronic microscopy, and energy dispersive spectrometry after extraction. The LF means were compared by means of Wilcoxon and Mann Whitney tests. Environmental scanning electron microscopy scores were compared among the groups using a Kruskal Wallis test, whereas the Ca/P ratio was evaluated by means of an Analysis of Variance with subparcels (treatments) and Tukey's post-hoc test. There were no statistically significant differences between the tooth pastes and between the orthodontic adhesives evaluated. Most teeth presented only partial enamel remineralization. Therefore, the fluoride released by the RMGIC was not enough to cause increased crystal regrowth in the acid-etched enamel. The use of fluoridated toothpaste did not provide positive additional effect.     

Evolution of the oxide structure of 9CrODS steel exposed to supercritical water

The corrosion behavior and oxide structure of 9CrODS steel in supercritical water has been studied. Samples were exposed to supercritical water at 500 and 600 °C for times of 2, 4 and 6 weeks. The oxide structure was studied using microbeam synchrotron X-ray diffraction and fluorescence analysis. The 600 °C samples exhibited a three-layer structure with Fe₃O₄ in the outer layer, a mixture of FeCr₂O₄ and Fe₃O₄ in the inner layer, and a mixture of metal and oxide grains (FeCr₂O₄ and Cr₂O₃) in the diffusion layer. Between the 2 and 4-week samples exposed to 600 °C supercritical water, a Cr₂O₃ film appeared at the diffusion layer-metal interface which appears to be associated with slower oxidation of the metal. The 500 °C samples also showed a three-layer structure, but both the outer and inner oxide layers contained mainly Fe₃O₄, and the diffusion layer contained much fewer oxide precipitates and was a solid solution of oxygen ahead of the oxide front.     

An integer goal programming model for determining capital expenditures for correctional facilities

The selection of capital expenditure projects for the construction of state correctional facilities is often complicated by the existence of multiple and conflicting objectives on the part of the various interest groups involved in the decision-making process. While some groups view the limited availability of state funds to construct such facilities as the paramount consideration, others might consider having adequate capacity to house prisoners in a satisfactory manner, and the effect of prison overcrowding on prisoner sentencing as the primary factors in the decision to construct new facilities. As such. it is imperative that the limited funds available for constructing correctional facilities be allocated in the most efficient and satisfactory manner possible. In this paper, integer goal programming is demonstrated via a case example as a means for allocating funds for capital expenditures for new and renovated correctional facilities. Sensitivity analysis is performed using the model in order to demonstrate its capability for testing various planning scenarios including alternative priority structures, goal constraints and goal levels.     

Local outlier detection reconsidered: a generalized view on locality with applications to spatial, video, and network outlier detection

Outlier detection research has been seeing many new algorithms every year that often appear to be only slightly different from existing methods along with some experiments that show them to “clearly outperform” the others. However, few approaches come along with a clear analysis of existing methods and a solid theoretical differentiation. Here, we provide a formalized method of analysis to allow for a theoretical comparison and generalization of many existing methods. Our unified view improves understanding of the shared properties and of the differences of outlier detection models. By abstracting the notion of locality from the classic distance-based notion, our framework facilitates the construction of abstract methods for many special data types that are usually handled with specialized algorithms. In particular, spatial neighborhood can be seen as a special case of locality. Here we therefore compare and generalize approaches to spatial outlier detection in a detailed manner. We also discuss temporal data like video streams, or graph data such as community networks. Since we reproduce results of specialized approaches with our general framework, and even improve upon them, our framework provides reasonable baselines to evaluate the true merits of specialized approaches. At the same time, seeing spatial outlier detection as a special case of local outlier detection, opens up new potentials for analysis and advancement of methods.     

Chemical imaging sensor and laser beacon

Design and functional aspects of PANSPEC, a panoramic-imaging chemical vapor sensor (PANSPEC is an abbreviation for infrared panoramic-viewing spectroradiometer), were advanced and its optical system reoptimized accordingly. The PANSPEC model unites camera and fused solid-state interferometer and photopolarimeter subsystems. The camera is an eye of the open atmosphere that collects, collimates, and images ambient infrared radiance from a panoramic field of view (FOV). The passive interferometer rapidly measures an infrared-absorbing (or infrared-emitting) chemical cloud traversing the FOV by means of molecular vibrational spectroscopy. The active photopolarimeter system provides a laser beam beacon. This beam carries identification (feature spectra measured by the interferometer) and heading (detector pixels disclosing these feature spectra) information on the hazardous cloud through a binary encryption of Mueller matrix elements. Interferometer and photopolarimeter share a common configuration of photoelastic modulation optics. PANSPEC was optimized for minimum aberrations and maximum resolution of image. The optimized design was evaluated for tolerances in the shaping and mounting of the optical system, stray light, and ghost images at the focal plane given a modulation transfer function metric.     

Managing major chemical accidents in China: towards effective risk information

Chemical industries, from their very inception, have been controversial due to the high risks they impose on safety of human beings and the environment. Recent decades have witnessed increasing impacts of the accelerating expansion of chemical industries and chemical accidents have become a major contributor to environmental and health risks in China. This calls for the establishment of an effective chemical risk management system, which requires reliable, accurate and comprehensive data in the first place. However, the current chemical accident-related data system is highly fragmented and incomplete, as different responsible authorities adopt different data collection standards and procedures for different purposes. In building a more comprehensive, integrated and effective information system, this article: (i) reviews and assesses the existing data sources and data management, (ii) analyzes data on 976 recorded major hazardous chemical accidents in China over the last 40 years, and (iii) identifies the improvements required for developing integrated risk management in China.     

调查发现因疫情而导致的消费者行为转变

Braze最新的消费者研究显示,新冠疫情引发了消费者行为的“永久性转变”,其中包括尝试新品牌的倾向、对品牌价值的“重新关注”以及整体上趋于谨慎的消费方式。