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81.
Joseph P. Gibbs 《Experimental Mechanics》1967,7(8):19A-26A
The historical development of the single active and “true” (zero gage factor) dummy weldable strain gage is reviewed. The combination of these devices into a half-bridge gage results in transducers capable of static-strain measurements at temperatures of 650 and 950° F for Ni?Cr alloy elements and Pt?W alloy elements, respectively. General application notes concerning these instruments are also included. 相似文献
82.
The effective elasticity tensor of a composite is defined to be the four-tensor C which relates the average stress to the average strain. We determine it for an array of rigid spheres centered on the points of a periodic lattice in a homogeneous isotropic elastic medium. We first express C in terms of the traction exerted on a single sphere by the medium, and then derive an integral equation for this traction. We solve this equation numerically for simple, body-centered and face-centered cubic lattices with inclusion concentrations up to 90% of the close-packing concentration. For lattices with cubic symmetry the effective elasticity tensor involves just three parameters, which we compute from the solution for the traction. We obtain approximate asymptotic formulas for low concentrations which agree well with the numerical results. We also derive asymptotic results for C at high inclusion concentrations for arbitrary lattice geometries. We find them to be in good agreement with the numerical results for cubic lattices. For low and moderate concentrations the approximate results of Nemat-Nasseret al., also agree well with the numerical results for cubic lattices. 相似文献
83.
A homogeneous, isotropic cylinder in an equilibrium state of plane strain, whose cross-section is a rectangle R : [0 < y
1 < 2L; 0 < y
2 < h] with h/L 1, is considered. There are no body forces and the long sides are stress free. At y
1 = 0 and y
1 = 2L, there are arbitrary loadings, each statically equivalent to a uniformly distributed tensile or compressive stress c. Within the theory of nonlinear elasticity and with the strains and strain gradients assumed to be sufficiently small (but with no such assumptions on the displacement gradients), it is proved that if (,=1,2) represents the Cauchy stress tensor and the Kronecker delta, then |–c11| decays exponentially to zero in R with distance from the nearer end, and the decay constant depends only upon the material but is independent of L. 相似文献
84.
Antony Forster Raj M. Joseph Sekhar S. 《Journal of Thermal Analysis and Calorimetry》2019,136(1):355-365
Journal of Thermal Analysis and Calorimetry - Domestic refrigerators have become an indispensable part of the modern life. Since they are connected to the electric mains and operate throughout the... 相似文献
85.
Abraham Sanenga Galefang Allycan Mapunda Tshepiso Merapelo Ludo Jacob Leatile Marata Bokamoso Basutli Joseph Monamati Chuma 《Entropy (Basel, Switzerland)》2020,22(11)
The open nature of radio propagation enables ubiquitous wireless communication. This allows for seamless data transmission. However, unauthorized users may pose a threat to the security of the data being transmitted to authorized users. This gives rise to network vulnerabilities such as hacking, eavesdropping, and jamming of the transmitted information. Physical layer security (PLS) has been identified as one of the promising security approaches to safeguard the transmission from eavesdroppers in a wireless network. It is an alternative to the computationally demanding and complex cryptographic algorithms and techniques. PLS has continually received exponential research interest owing to the possibility of exploiting the characteristics of the wireless channel. One of the main characteristics includes the random nature of the transmission channel. The aforesaid nature makes it possible for confidential and authentic signal transmission between the sender and the receiver in the physical layer. We start by introducing the basic theories of PLS, including the wiretap channel, information-theoretic security, and a brief discussion of the cryptography security technique. Furthermore, an overview of multiple-input multiple-output (MIMO) communication is provided. The main focus of our review is based on the existing key-less PLS optimization techniques, their limitations, and challenges. The paper also looks into the promising key research areas in addressing these shortfalls. Lastly, a comprehensive overview of some of the recent PLS research in 5G and 6G technologies of wireless communication networks is provided. 相似文献
86.
Munguia-Lopez Jose G. Juarez Rodrigo Muñoz-Sandoval Emilio Kalixto-Sanchez Marco A. Kinsella Joseph Matthew De Leon-Rodriguez Antonio 《Journal of nanoparticle research》2019,21(8):1-15
Journal of Nanoparticle Research - Workers are increasingly exposed to nanoparticles, mostly via inhalation. Respiratory protection is recommended as an additional control measure. Particulate... 相似文献
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