RH装置的多种设计概念

西马克美马克公司近些年来不断致力于改进RH装置的装备水平和冶金技术并取得了丰富的经验,其处理的钢水可以满足用户对在最短的处理周期及最小的工艺成本下获得极低碳或极低氢含量的要求.RH装置的形式可从单真空室到双工位双真空室快速更换等多种.本文以冶金和经济的角度详细地阐述了西马克美马克公司RH装置的概念和应用实践.西马克美马克公司在中国攀枝花钢铁集团公司最新投产的LF和RH装置就是我们二次精炼现代化工艺概念的代表.与西马克美马克公司的工艺自动化2级相似,其可以得到精确的成分,纯净的和最低的氢含量.工艺模型在线的修改方式也将有所介绍.     

Streamlining the Development Approval Process in a Post–Level of Service Los Angeles

Problem, research strategy, and findings: Local governments across the United States have for decades relied on the autocentric level of service (LOS) metric to analyze and impose exactions for the transportation impacts of land use developments. In California, LOS has dominated transportation impact analysis under the state’s project-level environmental review law. In that role, LOS has exacerbated the state’s notoriously tortuous development approval processes, particularly in urban areas. But LOS is on its way out. The state recently replaced LOS with vehicle miles traveled (VMT) as the primary measure—and basis for mitigation—of transportation impacts under the California Environmental Quality Act. Local governments must make the switch by July 1, 2020. We use a historical counterfactual approach to assess how replacing LOS with VMT could have affected the approval process for 153 land development projects over 16?years in the city of Los Angeles. We find that most projects could have benefited from at least some environmental review streamlining under the VMT-based framework recommended by the state, including more than 75% of residential-containing projects.

Takeaway for practice: Our results suggest that swapping LOS for VMT could reduce the environmental review burden for development in low-VMT urban areas and provide at least some of the approval process streamlining necessary to increase housing production in California. Similar impacts from an LOS-to-VMT switch could also potentially accrue outside of California under the right conditions, but more research is needed.     

Looking out to look in: inspiration from social sciences for construction management research

In reaction to the recent call for critical debate in the field of construction management research, I argue that we should embrace the richness of adjacent fields of study in order to dynamically develop our own and face the plethora of contemporary societal challenges that exist in our industry. I introduce the concepts of other-than-rational thinking in decision-making and multiplicity in management responses as examples of inspirational sources from social sciences that would contribute to truly understanding the driving forces of construction management processes. I connect these concepts to contemporary studies in construction management and share my experiences with several positive collaborative approaches in conducting construction management research.     

Effect of Post-weld Heat Treatment on Microstructure and Mechanical Properties of Laser Beam Welded TiAl-based Alloy

Post-weld heat treatment is carried out on the laser beam welded γ-TiAl-based alloy Ti-48Al-1Cr-1.5Nb-1Mn-0.2Si-0.5B (at. pct). The macro/microstructure and mechanical properties of both as-welded and heat-treated specimens are investigated by radiography, SEM, and tensile tests. Moreover, high energy synchrotron X-ray diffraction is performed to measure the residual stresses and evaluate the microstructure evolution. It is found that the residual stresses are distributed in a three-peak shape in the region of the weld zone and heat-affected zone of the as-welded specimen due to the microstructural transformation and heat softening. The residual stresses are largely relieved after the heat treatment. The heat-treated specimens have a near fully lamellar microstructure and show balanced mechanical properties of strength and ductility. The diffraction shows that the phase transformation from α ₂ to γ takes place under tensile load at 1023 K (750 °C), and the grain size and lamellar spacing are refined in the weld zone. Finally, the fracture mechanisms are found to be controlled by the local stress concentration-induced strain misfit between α ₂ and γ phases in the near γ grains and delamination and debonding in the lamellae. Boride ribbons of 5 μm in the near fully lamellar microstructure are found not to be detrimental to the tensile properties.     

On the importance of specific interface area in clay nanocomposites of PMMA filled with synthetic nano-mica

In clay nanocomposites, the specific interface area is the key factor determining potential improvements of properties. Nevertheless, in most systematic studies of nanocomposites little emphasis is put on assuring and characterizing dispersion quality. To probe the influence of dispersion quality, we compare nanocomposites filled with two layered silicates which were made by melt compounding and solution blending, respectively. Poly(methyl methacrylate) (PMMA) is chosen here as a thermoplastic model matrix which was compounded with a synthetic nano-mica (O-hect) and commercial Bentone with typical diameters of 5–7 μm and <300 nm, respectively.     

Surge arresters for insulation coordination in UHV power systems—related problems and solutions

Surge arresters play an important role in the insulation coordination of ultra high-voltage (UHV) electric power systems. In this contribution the requirements on the surge arresters are discussed in comparison with those in conventional applications, and how surge arrester standards are being changed to cover these special requirements.     

Statistical testing for sufficient control chart performances during monitoring of grouped processes

With ISO 7870-8, a standardized application of charting techniques for short runs and small mixed batches was presented in 2017. Similar to various scientific approaches, it requires that sample values from grouped processes follow nearly identical distributions. In practice, however, there tend to be differences between distribution parameters. Moreover, equal parameters do not ensure that distributions are properly aligned to the center line and control limits of the chart. These facts can lead to undesired control chart performances which can be expressed by average run lengths (ARL) during in-control and out-of-control conditions. In this work, a statistical test for sufficient control chart performances during monitoring of grouped processes based on preliminary samples is proposed. Control chart performances are defined as sufficient when they deviate within acceptable ranges from usual performances during single process monitoring in mass production. The ARL resulting from estimated distributions and planned production sequences is used as test statistic and calculated via the Markov chain approach. Exemplary tests are executed for scenarios with individuals and cumulated sum (CUSUM) charts. A simulative determination of error rates resulting from the ARL-based testing demonstrates its effectiveness in testing for sufficient control chart performances compared to an indirect testing with Levene's test and a one-way analysis of variance (ANOVA).     

An analysis of the transition proportion for binarization in handwritten historical documents

In this paper, we will present a mathematical analysis of the transition proportion for the normal threshold (NorT) based on the transition method. The transition proportion is a parameter of NorT which plays an important role in the theoretical development of NorT. We will study the mathematical forms of the quadratic equation from which NorT is computed. Through this analysis, we will describe how the transition proportion affects NorT. Then, we will prove that NorT is robust to inaccurate estimations of the transition proportion. Furthermore, our analysis extends to thresholding methods that rely on Bayes rule, and it also gives the mathematical bases for potential applications of the transition proportion as a feature to estimate stroke width and detect regions of interest. In the majority of our experiments, we used a database composed of small images that were extracted from DIBCO 2009 and H-DIBCO 2010 benchmarks. However, we also report evaluations using the original (H-)DIBCO?s benchmarks.