time differential
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2021 ◽  
Vol 11 (21) ◽  
pp. 10247
Author(s):  
Bo-Hun Choi ◽  
Dae-Cheol Seo ◽  
Yong-Seok Kwon ◽  
Il-Bum Kwon

An optical-fiber-embedded composite cylinder was fabricated using the filament winding process with an interval of 12 mm in the longitudinal direction of the cylinder. The optical fiber was wound 160 turns around the cylinder, and the straight length was about 125 m. After a total of twelve impact events of 5, 10, 15, and 20 J, the residual strain in the cylinder was measured using the proposed time differential BOCDA sensor system. This method makes the traditionally used optical delay unnecessary while increasing the degrees of freedom of using the modulation rate, which determines the spatial resolution of this measurement system. The modulation rates of optical light in the system were applied up to 16 Gbps, which is an eight-fold increase compared to our previous experiments. Damage maps were obtained by mapping the measured residual strain onto the structure of the cylinder, and compared using three spatial resolutions of 20, 10, and 6.25 mm. In the measured damage map, expansion deformation due to impact was measured at all impact points, and the impact location on the map and the actual location on the cylinder were exactly the same. The map measured from the composite showed a clear point-symmetrical shape with an increase in sharpness as the measurement resolution increased. At the highest resolution, material expansion and compression were observed to alternate with respect to the center of impact, like the surface deformation of a liquid caused by a thrown object. Furthermore, considered together with our previous experiments, we confirmed that this phenomenon propagated from the surface of the composite material to the interior, where the optical fiber was embedded. The total amount of residual strain formed around each impact point was linearly proportional to the applied external impact energy.


Author(s):  
Jian-Gen Liu ◽  
Xiao-Jun Yang ◽  
Yi-Ying Feng ◽  
Lu-Lu Geng

In this paper, we studied the generalized space and time fractional Korteweg–de Vries (KdV) equation in the sense of the Riemann–Liouville fractional derivative. Initially, the symmetry of this considered equation through the symmetry analysis method was obtained. Next, a one-parameter Lie group of point transformation was yielded. Then, this considered fractional model can be translated into an ordinary differential equation of fractional order via the Erdélyi–Kober fractional differential operator and the Erdélyi–Kober fractional integral operator. Finally, with the help of the nonlinear self-adjointness, conservation laws of the generalized space and time fractional KdV equation can be found. This approach can provide us with a new scheme for studying space and time differential equations of fractional derivative.


Mathematics ◽  
2021 ◽  
Vol 9 (16) ◽  
pp. 1983
Author(s):  
Bertrand Crettez ◽  
Naila Hayek ◽  
Peter M. Kort

This paper studies a discrete-time dynamic duopoly game with homogenous goods. Both firms have to decide on investment where investment increases production capacity so that they are able to put a larger quantity on the market. The downside, however, is that a larger quantity raises pollution. The firms have multiple objectives in the sense that each one maximizes the discounted profit stream and appreciates a clean environment as well. We obtain some surprising results. First, where it is known from the continuous-time differential game literature that firms invest more under a feedback information structure compared to an open-loop one, we detect scenarios where the opposite holds. Second, in a feedback Nash equilibrium, capital stock is more sensitive to environmental appreciation than in the open-loop case.


2021 ◽  
Vol 4 (1) ◽  
pp. 69-89
Author(s):  
Jakub Czajko

The special theory of relativity (STR) is operationally expanded onto orthogonal accelerations: normal  and binormal  that complement the instantaneous tangential speed  and thus can be structurally extended into operationally complete 4D spacetime without defying the STR. Thus the former classic Lorentz factor, which defines proper time differential  can be expanded onto  within a trihedron moving in the Frenet frame (T,N,B). Since the tangential speed  which was formerly assumed as being always constant, expands onto effective normal and binormal speeds ensuing from the normal and binormal accelerations, the expanded formula conforms to the former Lorentz factor. The obvious though previously overlooked fact that in order to change an initial speed one must apply accelerations (or decelerations, which are reverse accelerations), made the Einstein’s STR incomplete for it did not apply to nongravitational selfpropelled motion. Like a toy car lacking accelerator pedal, the STR could drive nowhere. Yet some scientists were teaching for over 115 years that the incomplete STR is just fine by pretending that gravity should take care of the absent accelerator. But gravity could not drive cars along even surface of earth. Gravity could only pull the car down along with the physics that peddled the nonsense while suppressing attempts at its rectification. The expanded formula neither defies the STR nor the general theory of relativity (GTR) which is just radial theory of gravitation. In fact, the expanded formula complements the STR and thus it supplements the GTR too. The famous Hafele-Keating experiments virtually confirmed the validity of the expanded formula proposed here.


2021 ◽  
Vol 1955 (1) ◽  
pp. 012092
Author(s):  
Yan Mi ◽  
Hengwei Zhang ◽  
Pengyu Sun ◽  
Jindong Wang

2021 ◽  
Vol 745 ◽  
Author(s):  
Fedor V. Konstantinov ◽  
H.M. Yeshwanth

The fauna of the bryocorine plant bug tribe Eccritotarsini from India and Sri Lanka is reviewed and updated. Ten genera and 20 species are reported from the region including two genera and six species described as new: Harpedona vittlaensis sp. nov., Lopidolon dandeliensis sp. nov., Mertila rubrocephala sp. nov., Namyatovia gen. nov. for N. castlerockensis gen. et sp. nov. (as the type species) and N. sirsiensis gen. et sp. nov., and Stonedahlia gen. nov. for S. mishmiensis gen. et sp. nov. The genus Bromeliaemiris Schumacher, 1919 is synonymized with Lopidolon Poppius, 1911. Dioclerus lutheri (Poppius, 1912) and Ernestinus ramkeshariae Yasunaga & Ishikawa, 2016 are reported from India for the first time. Differential diagnoses, keys, habitus photographs, illustrations of male genitalic structures, host and distributional information are provided for all genera and species.


2021 ◽  
Author(s):  
Francisco Ros

Abstract The fundamental equation that connects the magnitudes entropy and time has been found out by static thermodynamics for the first time: dS/S = dVI/V0 = kdτ, VI internal volume. Constant k also equals dT/Tdτ and is an individual characteristic for each isochoric adiabatic system in evolution. The constancy of k does not hold for a nonisochoric adiabatic system. In such manner time is introduced in the frame of thermodynamic variables as a genuine magnitude. The theoretically deduced entropy-time differential equation is empirically upheld by Newton cooling law. It was found in connection with an a priory, uncritical notion of thermodynamic equilibrium that irreversible heat capacity (CIR = TΔS/ΔT) drawing near to thermodynamic equilibrium is an indicator for the equilibrium. CIR is alike to statistical Boltzmann H in the approach to thermodynamic equilibrium, and the undisclosed connection of H with temperature is presented. The integrated entropy-time equation was modified by rotation of the coordinate axes to fulfill the necessary thermodynamic condition that pertinent irreversible heat (QIR = TΔS) is smaller than reversible heat (dQ = TdS), which is not embodied in the primitive S-τ differential equation. This thermodynamically indispensable rotation gives rise to an otherwise naive maximal entropy and an entropy-time maximum point. The transformation conveys a contraction of both entropy and time and is in agreement with the principle of minimal action.


2021 ◽  
Author(s):  
Yan Jin ◽  
Tong QI ◽  
Yuqing Ge ◽  
Jin Chen ◽  
Li juan Liang ◽  
...  

In this paper, ultrasensitive electrochemical determination of phosphate in water is achieved by hydrophilic TiO2 modified glassy carbon electrodes for the first time. Differential pulse voltammetry (DPV) method is proposed...


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