Statistically significant pattern mining (SSPM), which evaluates each pattern via a hypothesis test, is an essential and challenging data mining task for knowledge discovery. We introduce a ...preference relation between patterns and aim to discover the most preferred patterns under the constraint of statistical significance, which has never been considered in existing SSPM problems. We propose an iterative multiple testing procedure that can alternately reject a hypothesis and safely ignore the less useful hypotheses than the rejected one. By filtering out patterns with low utility, we can avoid the significance budget consumption of rejecting useless (uninteresting) patterns and focus the significance budget on more useful patterns, leading to more useful discoveries. We show that the proposed method can control the familywise error rate (FWER) under certain assumptions, which can be satisfied by a realistic problem class in SSPM. We also show that the proposed method always discovers equally or more useful patterns than Tarone-Bonferroni and Subfamily-wise Multiple Testing (SMT). Finally, we conducted several experiments with both synthetic and real-world data to evaluate the performance of our method. The proposed method discovered many more useful patterns in the experiments with real-world datasets than the existing method for all five conducted tasks.
High-density polyethylene (HDPE) is widely used for above-ground storage tanks (ASTs). However, there are currently no guidelines for the non-destructive testing (NDT) and evaluation (NDE) of HDPE ...ASTs. Moreover, the feasibility, limitations, and challenges of using NDT techniques for the field inspection of HDPE ASTs have not been well established. This study used both infrared thermography (IRT) and ultrasonic testing (UT) for the field inspection of HDPE ASTs. Highlighting the implementation challenges in the field, this study determined that: (1) ambient environmental parameters can affect IRT accuracy; (2) there is an ideal time during the day to perform IRT; (3) the heating source and infrared camera orientation can affect IRT accuracy; and (4) with proper measures taken, IRT is a promising method for flaw detection in HDPE ASTs. Additionally, UT can be used following IRT for detailed investigation to quantify the size and depth of defects. The manuscript concludes with a discussion of the limitations and best practices for the implementing of IRT and UT for HDPE AST inspections in the field.
This investigation utilized isothermal calorimetry (IC) to quantify the heat of hydration of steel furnace slag (SFS)-stabilized clays to assess the chemical aspects of the stabilization. ...Specifically, kaolin and bentonite clays were each blended with 40% of SFS by mass at water-to-binder ratios ranging from 1.0 to 1.5. The hydration properties of stabilized mixtures using lime (CaO) or portland cement (PC) were also tested for comparison at the same experimental conditions. The obtained thermal power and total heat curves of stabilized mixtures could contribute to confirming that there is a hydration process taking place in clay stabilized by SFS. Relative to lime and PC, the SFS performed similarly in terms of hydration heat behavior. When blended into clays, SFS provided a more significant hydration heat behavior than cement, but that was much milder than lime. X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were also employed to qualitatively analyze the mineralogy of the stabilized mixtures.
Pohang, a big city of Gyeongbuk province, South Korea, is developing rapidly in every aspect, containing many important infrastructures such as seaports, industrial factories, commercial centers, and ...underground electric facility systems that play an integral part in the contribution of electricity stemming from nuclear power plants. The main purpose of this research is a preliminary assessment of the earthquake hazard for underground electric facility lines (UEFL) located beneath Pohang city by using ArcGIS program. About 1000 drilling boreholes were collected as a database. All of the data were processed by filtering with respect to the depths, then the SPT-N values of unknown points were estimated by interpolation. Four interpolation methods (e.g., Inverse Distance Weighting (IDW), Kriging, Natural Neighbor, and Spline) were evaluated to find the method which gives the best representation of the SPT-N value for unknown points. The IDW method was finally selected. Afterwards, the border surface between soft- and hard-soil layers, the ground rock zonation map, the dramatic change of soil condition, and the depth of structure were determined as important scales to evaluate primarily whether the structures might be in danger or not when an earthquake occurs. In this way, proposed method can be applied to whole South Korea with over 100,000 available borehole data.
•Comprehensive literature review on physical and chemical treatments of ELT rubber.•Treatment methods summarized for using ELT rubber in cementitious composites.•Strength recovery index presented as ...a metric to compare different treatments.•Collated data identify the treatment methods that are most effective.
The use of end-of-life tire (ELT) rubber in rubberized cementitious materials (RCM) as a partial alternative aggregate has attracted the attention from researchers and industries in the recent decades. While the ELT rubber can be advantageous, such as by increasing fracture toughness, ductility, permeability, and thermal insulation of the concrete, it can negatively impact the other engineering properties, such as elastic modulus, mechanical strength, stiffness, and shrinkage. This reduction in performance may be attributed to the poor interfacial contact and bonding between the rubber particles and cement paste. This manuscript presents a comprehensive literature review on how ELT rubber has been physically and/or chemically treated to improve the properties of the rubberized cementitious composite. Specifically, this work (i) summarizes various treatment methods that have been employed to treat the ELT rubber surface before use in RCM; (ii) presents the hypothesized mechanism(s) behind each treatment method as well as the changes in the ELT rubber’s microstructure (if applicable); and (iii) provides discussions and comparisons between the developed pretreatment methods for ELT rubber. Two metrics – strength recovery index (SRI) and strength gain (SG) – are introduced to assist with comparisons. Also, recommendations are provided to assess the most effective pretreatment methods for ELT rubber in RCM in terms of engineering properties.
•Green binders made from industrial byproducts can be used instead of Portland cement in CLSM.•This article discusses the benefits of green binders on engineering properties of CLSM and provides an ...overview, standards, and their utilization.•The feasibility of using green binders in CLSM for sustainable production is established, with recommendations for future research.
Controlled low-strength materials (CLSM) are widely recognized as cementitious materials that are self-leveling and self-compacting, and are mainly used to replace conventional structural fillings and backfill soil. Conventionally, Portland cement (PC) is the main binder used to produce CLSM. Nevertheless, owing to a low unconfined compressive strength, it has the potential of utilizing new green binders, which can be developed by using industrial by-products, as partial or full replacements of cement in CLSM mixtures. This plays an essential role in the reduction of industrial by-products and waste disposal and eventually promotes contributions to sustainable development. This article critically reviews the utilization of new green binders in the production of CLSM. Specifically, this work (i) provides a comprehensive introduction to CLSM as well as typical standards and requirements for this material; (ii) introduces types of commonly used by-products as green binders in CLSM; (iii) discusses how these green binders have been utilized in CLSM in terms of dosages and how positive the green binders can enhance the engineering properties of CLSM; and (iv) provides constructive comparisons and discussions on the role and the effectiveness of each green binder in CLSM mixture as well as their environmental impacts when being used. Based on extensive previous studies, using green binders to replace cement in the sustainable production of CLSM was determined to be feasible. Several constructive recommendations for future research in CLSM with green binders were provided. It is believed that the work done in this article could provide a systematic summary and informative discussion and comparison to encourage researchers and practitioners to promote the practical applications of CLSM made of new green binders, leading to innovative contributions toward the sustainable development of civil infrastructures.
Experiments were conducted to investigate the leaching behavior of Zn from end-of-life tire rubber. XRD and XPS analyses showed that the Zn-containing phase in the material was mainly ZnO. SEM-EDS ...analysis confirmed the presence of both exposed and encapsulated ZnO particles. Acid leaching tests indicated that the carbon black comprised in the material can be oxidized and dissolved by HNO3, resulting in the dissolution of completely encapsulated ZnO particles with thinner covering layers. Then, leaching tests using HNO3 as the lixiviant were performed by varying acid concentration and leaching temperature. The results showed over 98% of Zn can be recovered using 2.0 mol/L HNO3 at 90 ℃ after 400 min of reaction. Leaching kinetic results were best fit with the Avrami model, indicating the leaching process was controlled by diffusion. The activation energy determined by Arrhenius formula was 12.92 kJ/mol, which further supports the proposed diffusion controlled leaching process.
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