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Electric and Magnetic Properties of Biological Materials
Published in Ben Greenebaum, Frank Barnes, Bioengineering and Biophysical Aspects of Electromagnetic Fields, 2018
Camelia Gabriel, Azadeh Peyman
In ferromagnetic materials, as in paramagnets, the magnetic susceptibility is positive, and these materials acquire a positive magnetization when placed in an applied field because of alignment of the spin moments in the material with the field. Unlike paramagnets, however, the net magnetization is not lost upon removal of the field (as long as the material is below a certain temperature, which will be discussed in a moment), and the induced moment in the material may be very strong (Figure 4.19). This is to say that ferromagnetic materials exhibit hysteresis.
Current Measurement
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
Most magnetic materials exhibit hysteresis. That is, the relationship between B and H depends on the history of the applied H. A plot of B versus H is called a hysteresis loop, and a sample is shown as Figure 21.3. The area of the loop represents energy. If a magnetic core is repeatedly driven around its hysteresis loop, there is a power loss that is proportional to the area of the loop and the frequency. A material with very large hysteresis is a permanent magnet.
The Performance of Diaphragms
Published in Mario Di Giovanni, Flat and Corrugated Diaphragm Design Handbook, 2017
Hysteresis cannot be calculated, but can be minimized or nearly eliminated by proper choice of material and stress level. However, the designer may not have the choice of designing with low-hysteresis materials, as compatibility with process media may dictate materials poor in hysteresis characteristics. For example, corrosion resistance with pressure media may dictate materials such as tantalum or even platinum—materials which cannot be heat-treated or which are of un-suitable hardness level. Here, the recourse available is to keep the stress level as low as possible or to design a diaphragm which can be backed up with a heat-treated elastic member of a higher spring constant—thus complicating the problem.
Seismic-induced poundings in highway and high-speed railway bridges: a state-of-the-art review
Published in Structure and Infrastructure Engineering, 2023
Dongliang Meng, Menggang Yang, Tianyue Sun, Xuhui He, Nawawi Chouw
Installing steel bar/cable restrainers between adjacent decks or between decks and piers is a primary mitigation measure to prevent pounding-induced girder dislocation (DesRoches & Fenves, 2000; Shrestha & Hao, 2016). Steel restrainers were also found to be effective to reduce the girder rotation of skewed bridges (Kawashima & Shoji, 2000) and curved bridges (Ruiz Julian et al., 2007). The main drawback of steel restrainers is their poor energy dissipation capacity, and consequently they are ineffective to reduce seismic force developed in bridges (Abdel-Ghaffar et al., 1997). Shape memory alloy (SMA) has superior energy dissipation capacity because of its flag-shaped hysteresis curve under cyclic loads (DesRoches & Delemont, 2002; Shrestha & Hao, 2016). Moreover, SMA can withstand large deformation and return to its undeformed shape following loading. Therefore, SMA-based restrainers have been favored by many researchers and engineers. Andrawes and DesRoches (2005) indicated that SMA restrainers are more effective than conventional steel restrainers in reducing the relative displacement between adjacent segments. Further studies by Padgett et al. (2009), Guo et al. (2012) and Shrestha et al. (2018) also highlighted the effectiveness of SMA restrainers in reducing the adverse effect of poundings on bridges. It should be noted that the mechanical performance of SMA is usually affected by ambient temperature, which is a drawback of SMA-based restrainers in addition to the high cost (Shrestha et al., 2017).
Autonomous materials discovery and manufacturing (AMDM): A review and perspectives
Published in IISE Transactions, 2023
Over the past decade, several variants of EGO have been developed by advancing the BO principles (MacKay, 1992; Cohn et al., 1996; Chan et al.,2010). This is because EI, as a traditional BO acquisition function, is criticized for over-exploiting the fitted model and under-exploring the design space (Bull, 2011; Chen et al., 2019). Balancing exploration and exploitation is an important step for reaching the global optimum of a continuous function or approximating the whole response surface using limited samples. The “balance” should nonetheless be driven by the search or discovery goal. Such goals can be one of the three kinds: (a) improve a possibly multivariate response, as in the hysteresis characteristic of a shape memory alloy material, or machinability of a refractory high-entropy alloy (exploitation); (b) increase the knowledge of the P→S or S→P relationship connecting the input design parameters of the MDS and the manufacturing recipe, the material structure and the properties (exploration); or (c) simultaneously understanding the underlying space while improving the response (balance).
One-pot synthesis of magnetic chitosan/iron oxide bio-nanocomposite hydrogel beads as drug delivery systems
Published in Soft Materials, 2021
S. Barkhordari, A. Alizadeh, M. Yadollahi, H. Namazi
To explore the magnetic properties of the CH/MION nanocomposite hydrogel beads, the magnetization curve was determined from Vibrating Sample Magnetometer (VSM) at room temperature (300 K) Figure 3 shows the magnetization of CH/MION15 sample as a function of the magnetic field in the range of −15,000 to 15,000 Oe. The magnetization increased with an increase in the magnetic field. Moreover, the magnetic hysteresis loops are S-like curves and have no coercivity and remanence, implying that there is no remaining magnetization when the external magnetic field is removed. These results indicate that the magnetic composites exhibit typical superparamagnetic behavior, and the single-domain magnetite NPs remained in the composite. The VSM plot present values of 4.73 emu.g−1 for the saturation magnetization (Ms) of the CH/MION15 sample