Calorimetrically measured enthalpies for the reaction of H2(D2) (g) with Ti and Ti-Ni alloys at 323 K

Reaction enthalpies have been measured calorimetrically at 323 K for the reaction 1/2H₂ (g) + Ti (α, hcp) → TiH_1.5 and for the partial molar solution of H₂ in the δ phase. The magnitude of the enthalpy decreases from 68 at H/Ti = 0 to 65 kJ/mol H at H/Ti = 1.5. The enthalpy continues to slowly fall in magnitude with the increase of H content, and then, for (H/Ti) > 1.9, it falls more precipituously. ΔH _f ⁰ (TiH_1.5) = −98.4 kJ and ΔH _f ⁰ (TiH₂) = −130.3 kJ evaluated at 323 K. No differences in enthalpies were found between H and D. The results are discussed in terms of the existing solvus data for this system, which are important for the quantitative understanding of hydride-induced fracture. Enthalpies of reaction with H₂ have been determined for several Ti-Ni alloys which lie in the (Ti(α) + Ti₂Ni) two-phase field. The reaction with H₂ initially occurs with the Ti phase and then with the Ti₂Ni phase. The enthalpies are similar for the Ti phase as for pure Ti, indicating that this phase is relatively pure Ti. Reaction with the Ti₂Ni phase shows a plateau region with an enthalpy of reaction with 1/2H₂ of about −30 kJ/ mol H. Formerly Graduate Student, Department of Chemistry, University of Vermont.     

Auxiliary ventilation in mining roadways driven with roadheaders: Validated CFD modelling of dust behaviour

The production of dust when driving mining roadways can affect workers health. In addition, there is a decrease in productivity since Mine Safety regulations establish a reduction in the working time depending on the quartz content and dust concentration in the atmosphere.One of the gate roadways of the longwall named E4-S, belonging to the underground coal mine Carbonar SA located in Northern Spain, is being driven by an AM50 roadheader machine. The mined coal has a high coal dust content.This paper presents a study of dust behaviour in two auxiliary ventilation systems by Computational Fluid Dynamics (CFD) models, taking into account the influence of time. The accuracy of these CFD models was assessed by airflow velocity and respirable dust concentration measurements taken in six points of six roadway cross-sections of the mentioned operating coal mine.It is concluded that these models predicted the airflow and dust behaviour at the working face, where the dust source is located, and in different roadways cross-sections behind the working face.As a result, CFD models allow optimization of the auxiliary ventilation system used, avoiding the important deficiencies when it is calculated by conventional methods.     

Multiple scale meshfree methods for damage fracture and localization

The Reproducing Kernel Particle Method (RKPM), which utilizes the fundamental notions of the convolution theorem, multiresolution analysis and meshfree properties, is reviewed. The multiple-scale RKPMs are then proposed as an alternative to commonly used numerical methods such as the finite element method. The elimination of a mesh, combined with the filtering properties of window functions, makes a particle method suitable for problems with large deformations, high gradients, and localization problems. This class of methods has been applied to shear band problems, and large deformation fracture and damage problems.     

Quality of Crude Oil Extracted from Aging Walleye Pollock (<Emphasis Type="Italic">Theragra chalcogramma</Emphasis>) Byproducts

The quality of crude oil was examined as a function of the temperature and delay time between collecting and processing the fish byproducts from a commercial cannery into crude oil. Extracts from pollock byproducts stored at 6 and 15 °C for up to 4 and 10 days was examined. Longer storage of byproducts resulted in higher free fatty acid (FFA) and an increase in retinol levels in the extracted crude oils. Primary and secondary oxidation assays consisting of peroxide value and thiobarbituric acid-reactive substances increased initially with storage time on day 1 followed by an unexpected decrease with storage time. Higher storage temperature resulted in greater FFA and retinol levels, but lower oxidation products in the crude oils. The tocopherol levels decreased with storage time of the byproducts with no differences between the storage temperatures. Eicosapentaenoic acid, docosahexaenoic acid and polyunsaturated fatty acids percentage remained similar in the extracted oils with the respective storage time or temperature treatments.     

核磁共振法确定多孔介质的性能

核磁共振技术(NMR)是一种有力而安全的用于获取介质的空间分辨信息的方法。分析NMR数据的新方法能提供研究各种物理体系的机遇。本文讨论了核磁探针法的实验和分析进展。该方法用于定量评价表征流体和其在多孔介质中的流动行为。这种探针法的核心是辅助函数评价问题的求解,而这类问题的求解决依赖于用B spline表示法对未知函数的规整化和序列评估。     

Key attributes of the SAPHIRE risk and reliability analysis software for risk-informed probabilistic applications

The Idaho National Laboratory is a primary developer of probabilistic risk and reliability analysis (PRRA) tools, dating back over 35 years. Evolving from mainframe-based software, the current state-of-the-practice has led to the creation of the SAPHIRE software. Currently, agencies such as the Nuclear Regulatory Commission, the National Aeronautics and Aerospace Agency, the Department of Energy, and the Department of Defense use version 7 of the SAPHIRE software for many of their risk-informed activities. In order to better understand and appreciate the power of software as part of risk-informed applications, we need to recall that our current analysis methods and solution methods have built upon pioneering work done 30–40 years ago. We contrast this work with the current capabilities in the SAPHIRE analysis package. As part of this discussion, we provide information for both the typical features and special analysis capabilities, which are available. We also present the application and results typically found with state-of-the-practice PRRA models. By providing both a high-level and detailed look at the SAPHIRE software, we give a snapshot in time for the current use of software tools in a risk-informed decision arena.     

Distinguishing Wild vs. Stocked Lake Trout (Salvelinus namaycush) in Lake Ontario: Evidence from Carbon and Oxygen Stable Isotope Values of Otoliths

We investigated the potential for using carbon and oxygen isotope values of otolith carbonate as a method to distinguish naturally produced (wild) lake trout (Salvelinus namaycush) from hatchery-reared lake trout in Lake Ontario. We determined δ ¹³C_(CaCO3) and δ ¹⁸O_(CaCO3) values of otoliths from juvenile fish taken from two hatcheries, and of otoliths from wild yearlings. Clear differences in isotope values were observed between the three groups. Subsequently we examined otoliths from large marked and unmarked fish captured in the lake, determining isotope values for regions of the otolith corresponding to the first year of life. Marked (i.e., stocked) fish showed isotope ratios similar to one of the hatchery groups, whereas unmarked fish, (wild fish or stocked fish that lost the mark) showed isotope ratios similar either to one of the hatchery groups or to the wild group. We interpret these data to suggest that carbon and oxygen isotope values can be used to determine the origin of lake trout in Lake Ontario, if a catalogue of characteristic isotope values from all candidate years and hatcheries is compiled.     

Wind Pressures on Parapets of Flat Roofs

A wind-tunnel study has been carried out to assess wind pressures acting on parapets, including their top surfaces. Local and area-averaged pressure coefficients were measured on parapets of flat-roof models with a length to height ratio (L/H) of 1:1, 2:1, and 3:1. The results were obtained for full-scale equivalent parapet heights of 1 and 2 m and for wind directions ranging from zero to 315°. The local wind load on the parapet was found to be approximately 30% larger at the windward corner of the building than at the midspan location. Maximum parapet loads for the low building model were approximately 30% larger than those for the cubical model. Parapet height did not significantly affect the peak local load on the parapet except in the corner region, where the inward load (toward the roof) for the 1 m parapet was 25% higher than that for the 2 m parapet.     

Stiffness properties and stiffness orientation distributions for various paper grades by non-contact laser ultrasonics

The stiffness properties, especially flexural rigidity (FR), out of plane shear rigidity (SR), and stiffness orientation distributions (SOD) are characterized for various paper grades, by a laser ultrasonics instrument. Laser ultrasonics generation is achieved through thermal dilatation by point focusing of a pulsed laser beam onto the surface of the specimen. By probing the excited broadband ultrasound propagating in the samples, the velocities dispersions are obtained and the materials properties are extracted. The measured FR and SR along machine direction (MD) and cross direction (CD) are presented for 10 paper samples ranging from thin copy papers to heavy linerboards. The SOD polar diagrams for some of the samples are also presented and discussed. The relationships of FR, SR, Young's and shear moduli with basis weight are discussed. It is observed that both the Young's and shear moduli tend to decrease significantly when the basis weight increases, going from copy paper to linerboard grades. We also found that SR reaches a maximum value and then decreases when the basis weight increases to 150 g/m² and above. This unusual behavior of SR can be explained by the noticeable reduction of shear modulus for heavy linerboards.