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A practical bit condition monitoring system is a necessary component of autonomous drilling. Tricone bits are widely used in blasthole drilling in mining. Bits experience a variety of wear mechanisms during the operation and rolling element failure is the dominant catastrophic failure mode of tricone bits. Bit lifetime and performance significantly vary based on the working condition and the critical components of the bit i.e. rolling elements, are invisible to the direct condition monitoring systems. At McGill University, extensive research work is conducted to develop an indirect bit condition monitoring and failure prediction approach relying on the vibration signals and the technology is currently patent pending. This article presents real-world experimental evidence to show the unreliability of conservative bit changing strategy based on the bit operation life or drop in the rate of penetration (ROP) and ineffectiveness of direct wear monitoring techniques to cover the dominant failure mode.
Objective
To demonstrate the unreliability of tricone bit replacement relying on bit operation life or ROP measurement and ineffectiveness of vision-based monitoring techniques for autonomous drilling.
Obtaining a good statistical representation of material microstructures is crucial for establishing robust process–structure–property linkages and machine learning techniques can bridge this gap. One major difficulty in leveraging recent advances in deep learning for this purpose is the scarcity of good quality data with enough metadata. In machine learning, similarity metric learning using Siamese networks has been used to deal with sparse data. Inspired by this, the authors propose a Siamese architecture to learn microstructure representations. The authors show that analysis tasks such as the classification of microstructures can be done more efficiently in the learned representation space.
A variety of machines are currently being used for mechanical excavation in mining and civil industries. A series of research works have been conducted at McGill University in the past decade to study the effects of microwave (MW) irradiation on rock mechanical properties. The idea is to enhance the excavation performance by improving the rate of penetration and decreasing the wear rate on the cutting tools. These two effects would eventually translate into economic benefits for mine operators. The effectiveness of MW on weakening rocks is proven, however the most efficient method to employ MW in mines is still under investigation. This article presents some experimental results on the effects of cooling- rate on rock strength. Brazilian Tensile Strength (BTS) of microwave treated samples were compared in natural air-cooled and water rapid-cooled conditions.
The influence of nutrient loading and other anthropogenic stressors is thought to be greater in low inflow, microtidal estuaries, where there is limited water exchange. This 11-month study compared spatial changes in macrofaunal communities adjacent to regions that varied in land cover in Oso Bay, Texas, an estuarine secondary bay with inflow dominated by hypersaline discharge, in addition to discharge from multiple municipal wastewater treatment plants. Macrofauna communities changed in composition with distance away from a wastewater treatment plant in Oso Bay, with the western region of the bay containing different communities than the head and the inlet of the bay. Ostracods were numerically dominant close to the wastewater discharge point. Macrobenthic community composition is most highly correlated with silicate concentrations in the water column. Silicate is negatively correlated with salinity and dissolved oxygen, and positively correlated with nutrients within the bay. Results are relevant for environmental management purposes by demonstrating that point-source discharges can still have ecological effects in hydrologically altered estuaries.
There are numerous associations between psychological characteristics and political values, but it is unclear whether messages tailored to these psychological characteristics can influence political decisions. Two studies (N = 398, N = 395) tested whether psychological-based argument tailoring could influence participants’ decision-making. We constructed arguments based on the 2016 Brexit referendum; Remain supporters were presented with four arguments supporting the Leave campaign, tailored to reflect the participant’s strongest (/weakest) moral foundation (Loyalty or Fairness) or personality trait (Conscientiousness or Openness). We tested whether individuals scoring high on a trait would find the tailored arguments more persuasive than individuals scoring low on the same trait. We found clear evidence for targeting, particularly for Loyalty, but either no evidence or weak evidence, in the case of Conscientiousness, for tailoring. Overall, the results suggest that targeting political messages could be effective, but provide either no, or weak evidence that tailoring these messages influences political decision-making.
Earlier work by the authors suggested that the formation of molten eutectic regions in Mg-Ca binary alloys caused a discrepancy in ignition temperature when different heating rates are used. This effect was observed for alloys where Ca content is greater than 1 wt%. In this work, the effect of two heating rates (25 °C/min and 45 °C/min) on the ignition resistance of Mg-3Ca is evaluated in terms of oxide growth using X-ray Photoelectron Spectroscopy. It is found that the molten eutectic regions develop a thin oxide scale of ~100 nm rich in Ca at either heating rate. The results prove that under the high heating rate, solid intermetallics are oxidized forming CaO nodules at the metal/oxide interface that eventually contribute to the formation of a thick and non-protective oxide scale in the liquid state.
A growing number of developments in biology and materials chemistry highlight the notion of bioinspiration – in which biological concepts, mechanisms, functions, and design are the starting points toward new synthetic materials and devices with advanced structures and functions [1]. There is no doubt that emerging and reemerging infectious diseases caused and transmitted by viruses have significantly impacted human health worldwide [2,3]. Clearly, the virus exhibits elegant architectures that could occasionally be cellular macromolecules with structures that are beautifully adapted to the functions of the virion [4]. Virus particles exist in many sizes and shapes, and they vary considerably in the number and nature of the molecules from which they are built. Most viruses show a characteristic size, in the range of tens to hundreds of nanometers [5]. Viruses are intracellular parasites that enter a host cell/body to deliver their genetic material to initiate infection. Usually, the first step in the life cycle of a virus is the attachment to host cells/bodies. These may include their abilities to interact with lipids, proteins, and sugar moieties on the surface of cells and tissue [6].
Oral health is of great importance to people’s general health. Dental disease is more prevalent than most people imagine. For example, caries, which can lead to partial or total loss of teeth, affect almost 100% adults and 60–90% of schoolchildren [1]. To correct the dental malfunction caused by tooth loss due to various reasons, such as caries, aging, injury, etc, dental crowns have been adopted as a common treatment.
In the past, significant research has been focused on improving the mechanical properties of lightweight structural materials due to the large demand in bioengineering, aerospace, automotive, armor, and construction applications. This primarily includes advanced structural materials, which are lightweight materials with outstanding mechanical properties such as strength and toughness. Meanwhile, various materials exist in nature that inherently have these exceptional mechanical properties [1]. There is, therefore, a great interest in understanding and analyzing the structure and mechanical behavior of these materials [2]–[7]. Evolution has brought about beautiful, optimized solutions to many problems. Nacre [8], mantis shrimp club [9], bone [10], deep sea sponge [11], bamboo [12,13], and elk antler [14] are just a few of these structural biological materials.
In recent years, there has been significant interest in the fields of bioinspired design and biomimetics [1]. Bioinspired design involves the use of scientific and engineering principles in the design of engineering components and structures that are inspired by biological systems. In contrast, biomimetics involves the design of engineering components and structures that copy biological systems. Hence, airfoils and aircraft wings are examples of bioinspired design that are inspired by bird flight but guided by the principles of lift and drag from aerodynamics. In contrast, the early idea of an airplane with flapping wings is an example of biomimetics, which is based on the simple idea of copying nature without thinking carefully about the underlying scientific principles that enable such natural systems to function in the way that they do.
Global warming is a pressing issue for both current and future generations. The various impacts of improper environmental handling have led to drought, famine, flooding, and other natural disasters. In addition, current global energy consumption is growing exponentially, and dependence on foreign oil and gas not only negatively affects the environment but also creates national dependencies that endanger social stability [1]. An alternative, environmentally friendly energy source is therefore required to preserve nature and fulfill this ever-growing need for energy. However, clean energy sources, such as solar radiation, wind, and waves, are intermittent and require energy storage platforms [2]. To this end, high energy density rechargeable batteries have recently attracted tremendous research attention as they enable efficient storage of intermittent clean energy and electrification of transportation vehicles. Similar to fossil fuels, batteries store energy as portable chemical energy, which is the most convenient form of storage.
Single-crystal and powder X-ray diffraction data, collected at room temperature, unit-cell parameters and space group for eluxadoline nitrate monohydrate, C32H35N5O5⋅2HNO3⋅H2O, are reported [a = 11.066(5) Å, b = 13.452(6) Å, c = 24.373(9) Å, unit-cell volume V = 3628.15 Å3, Z = 4, ρcal = 1.344 g⋅cm−3, and space group P212121]. All the diffraction peaks in the experimental pattern have been indexed and are consistent with the P212121 space group.
Since the advent of the first programmable robotic arm in the early 1960s by George C. Devol, the robotics industry has seen fast growth, and nowadays robotic arms are ubiquitous in automobile assembly lines. In addition to those fixed to the ground as in the robotic arm case, autonomous mobile robots have also been designed and manufactured, and have found ample applications in many areas such as space and deep-sea exploration, thanks to synergistic progress in control, actuation, and information technology, among others. These robots are featured with high accuracy for force and position control. They are ideal for repetitive tasks that quickly bore humans. They make many fewer mistakes. Their bodies are made of hard materials, such as metals and hard plastics, while their control and actuation units use metal or semiconductors such as silicon for electronics.
In recent years, there has been considerable interest in developing novel underwater vehicles that use propulsion systems inspired by biology [1,2]. Such vehicles have the potential to uncover new mission capabilities and improve maneuverability, efficiency, and speed [3,4]. Here we will explore the physical mechanisms that govern the performance – especially swimming speed and efficiency – of propulsive techniques inspired by biology. We will also show that we can translate the understanding we have gained from biology to the design of a new generation of underwater vehicles.
Bamboo is a group of perennial grasses in the family Poaceae, subfamily Bambusoideae, tribe Bambuseae [1]. One estimation classified bamboo into 75 genera and approximately 1,500 species [1]. The ordinary species of giant bamboo includes Phyllostachys heterocycla pubescens (Moso), Bambusa stenostachya (Tre Gai), Guadua angustifolia (Guadua), and Dendrocalamus giganteus (Dendrocalamus). Moso is the most widely distributed bamboo for utilization [2]. This species is native to China, and was introduced to Japan in about 1736 and to Europe before 1880 [2]. The word, moso (in Japanese) or mao zhu (in Chinese), means hairy culm sheaths and this bamboo is named for the pubescent down at the bottom of its new culms.