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Topic Review
Solid Acid Catalysts for Hock Cleavage of Hydroperoxides
The oxidation of cumene and following cleavage of cumene hydroperoxide (CHP) with sulfuric acid (Hock rearrangement) is still, by far, the dominant synthetic route to produce phenol. In 2020, the global phenol market reached a value of 23.3 billion US$ with a projected compound annual growth rate of 3.4% for 2020–2025. From ecological and economical viewpoints, the key step of this process is the cleavage of CHP. One sought-after way to likewise reduce energy consumption and waste production of the process is to substitute sulfuric acid with heterogeneous catalysts. Different types of zeolites, silicon-based clays, heteropoly acids, and ion exchange resins have been investigated and tested in various studies. For every type of these solid acid catalysts, several materials were found that show high yield and selectivity to phenol.
  • 885
  • 19 Jan 2022
Topic Review
Glucose Monitoring
Glucose monitoring is essential to control diabetes and avoid long-term complications. Diabetics suffer on a daily basis with the traditional glucose monitors currently in use, which are invasive, painful, and cost-intensive. Therefore, the demand for non-invasive, painless, economical, and reliable approaches to monitor glucose levels is increasing.
  • 885
  • 30 Oct 2021
Topic Review
Recent Advances of Wearable Sweat-Sensing Devices
A sweat-sensing device requires a wearable device for the temporary attachment of its main components, including sensors, sweat collection devices, and electronic devices to the body’s skin region.
  • 885
  • 21 Oct 2022
Topic Review
Assessment of Computer Vision-Based Construction Progress Monitoring Process
The progress monitoring (PM) of construction projects is an essential aspect of project control that enables the stakeholders to make timely decisions to ensure successful project delivery, but ongoing practices are largely manual and document-centric. However, the integration of technologically advanced tools into construction practices has shown the potential to automate construction PM (CPM) using real-time data collection, analysis, and visualization for effective and timely decision making. CPM entails periodically measuring the on-site progress and comparing the data with a planned schedule to get the actual status of a construction project. Traditional CPM practices involve manual data collection, which requires human intervention and hence are slow, error-prone, and labor-intensive. To overcome these issues, various automated CPM processes have been proposed. These processes include but are not limited to the use of enhanced information, geospatial, and imaging technologies. The imaging technologies comprise photogrammetry, videogrammetry, laser scanning, and range imaging. Laser scanning is a promising tool for as-built DAQ due to its accuracy; however, it requires expensive equipment, is technically complex, and requires experts to capture, model, and manipulate data for meaningful interpretations. An alternate technique is CV-based technology, which comprises photogrammetry, videogrammetry, and range images. The CV-based CPM comprises four sub-processes: data acquisition (DAQ), information retrieval, progress estimation, and output visualization. Each process involves various methods and techniques to achieve the desired output posing several benefits and limitations.
  • 885
  • 05 Aug 2022
Topic Review
Microfluidics to Study Membrane Filtration
Membrane filtration processes are best known for their application in the water, oil, and gas sectors, but also in food production they play an eminent role. Filtration processes are known to suffer from a decrease in efficiency in time due to e.g., particle deposition, also known as fouling and pore blocking. Although these processes are not very well understood at a small scale, smart engineering approaches have been used to keep membrane processes running. Microfluidic devices have been increasingly applied to study membrane filtration processes and accommodate observation and understanding of the filtration process at different scales, from nanometer to millimeter and more. In combination with microscopes and high-speed imaging, microfluidic devices allow real time observation of filtration processes.
  • 884
  • 24 Nov 2020
Topic Review Video
3D Visualisation in Railway Tunnel SubSurface Inspection
Railway Tunnel SubSurface Inspection (RTSSI) is essential for targeted structural maintenance. ‘Effective’ detection, localisation and characterisation of fully concealed features (i.e., assets, defects) is the primary challenge faced by RTSSI engineers, particularly in historic masonry tunnels. Clear conveyance and communication of gathered information to end-users poses the less frequently considered secondary challenge.
  • 884
  • 22 Nov 2022
Topic Review
Ionocraft
An ionocraft or ion-propelled aircraft (commonly known as a lifter or hexalifter) is a device that uses an electrical electrohydrodynamic (EHD) phenomenon to produce thrust in the air without requiring any combustion or moving parts. The term "ionocraft" dates back to the 1960s, an era in which EHD experiments were at their peak. In its basic form, it simply consists of two parallel conductive electrodes, one in the form of a fine wire and another which may be formed out of wire grid, tubes or foil skirts with a smooth round surface. When such an arrangement is powered by high voltage (in the range of a few kilovolts), it produces thrust. The ionocraft forms part of the EHD thruster family, but is a special case in which the ionisation and accelerating stages are combined into a single stage. The device is a popular science fair project for students. It is also popular among anti-gravity or so-called "electrogravitics" proponents, due to the research of Thomas Townsend Brown, who built these devices in the 1920s and incorrectly believed that he had found a way to modify gravity using electric fields. The term "lifter" is an accurate description because it is not an anti-gravity device; rather, it produces lift using the same basic principle as a rocket, i.e. from the equal but opposite force upward generated by the driving force downward, specifically by driving the ionized air downward in the case of the ionocraft. Much like a rocket or a jet engine (it can actually be much more thrust efficient than a jet engine), the force that an ionocraft generates is consistently oriented along its own axis, regardless of the surrounding gravitational field. Claims of the device also working in a vacuum have been disproved. Ionocraft require many safety precautions due to the high voltage required for their operation; nevertheless, a large subculture has grown up around this simple EHD thrusting device and its physics are now known to a much better extent.
  • 884
  • 01 Dec 2022
Topic Review
Flexible Fluxgate Sensor
Fluxgate sensors are magnetic flux density measurement instruments. They are high-accuracy direction sensitive magnetometers that include the Earth’s magnetic field in their measuring range. For this reason, they are commonly used for magnetic compass applications. Among others, many current measurement devices are based on fluxgate sensors, since they can measure DC magnetic fields as well as low-frequency AC magnetic fields.
  • 884
  • 01 Nov 2020
Topic Review
Fuzzy Algorithms in Multi-Motor Systems
Multi-motor systems are strong coupled multiple-input–multiple-output systems with independent or mechanically interconnected motors. The main objective in multi-motor drive control is to achieve synchronized operation of all motors in the system. In this paper, multi-motor systems are classified in accordance with their control demands. The review of recent research literature indicates that fuzzy algorithms are widely used in multi-motor control.
  • 883
  • 13 Nov 2020
Topic Review
Biofuels for Spark Ignition Engines
Biofuels are receiving increased scientific attention, and recently different biofuels have been proposed for spark ignition engines. Different biofuels, mainly ethanol, methanol, i-butanol-n-butanol, and acetone, are blended together in single dual issues and evaluated as renewables for SIE. Each blend showed some advantaged and drawbacks in terms of emissions and performance. 
  • 883
  • 17 Mar 2021
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