Experimental studies on the shear capacity of sea sand concrete beams with basalt fiber-reinforced polymer bars

Basalt fiber-reinforced polymer (BFRP) bars can replace steel bars in sea sand concrete structures to prevent the corrosion of steel by chloride ions; thus, sea sand can be directly added to concrete material in construction. Shear tests on 16 sea sand concrete beams with BFRP bars (including ten beams with stirrups and six beams without stirrups) are performed, and their failure modes, shear capacities and influencing factors are analyzed. The results reveal two main failure modes for sea sand concrete beams with BFRP bars: bending failure and shear-compression failure. The shear capacity increases with the concrete strength and stirrup ratio but decreases with an increased shear-span ratio, and the longitudinal reinforcement ratio has an insignificant effect on shear capacity

Mathematical Analysis of Some Typical Problems in Geodesy by Means of Computer Algebra

There are many complicated and fussy mathematical analysis processes in geodesy, such as the power series expansions of the ellipsoid’s eccentricity, high order derivation of complex and implicit functions, operation of trigonometric function, expansions of special functions and integral transformation. Taking some typical mathematical analysis processes in geodesy as research objects, the computer algebra analysis are systematically carried out to bread, deep and detailed extent with the help of computer algebra analysis method and the powerful ability of mathematical analysis of computer algebra system. The forward and inverse expansions of the meridian arc in geometric geodesy, the nonsingular expressions of singular integration in physical geodesy and the series expansions of direct transformations between three anomalies in satellite geodesy are established, which have more concise form, stricter theory basis and higher accuracy compared to traditional ones. The breakthrough and innovation of some mathematical analysis problems in the special field of geodesy are realized, which will further enrich and perfect the theoretical system of geodesy

(E)-Methyl 3-(1H-indol-2-yl)acrylate

The title compound, C12H11NO2, is close to being planar (r.m.s. deviation for the non-H atoms = 0.033 Å). In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds, generating C(7) chains running along the b axis. A weak C—H⋯O interaction helps to establish the packing

Achieving quantum precision limit in adaptive qubit state tomography

The precision limit in quantum state tomography is of great interest not only to practical applications but also to foundational studies. However, little is known about this subject in the multiparameter setting even theoretically due to the subtle information tradeoff among incompatible observables. In the case of a qubit, the theoretic precision limit was determined by Hayashi as well as Gill and Massar, but attaining the precision limit in experiments has remained a challenging task. Here we report the first experiment which achieves this precision limit in adaptive quantum state tomography on optical polarization qubits. The two-step adaptive strategy employed in our experiment is very easy to implement in practice. Yet it is surprisingly powerful in optimizing most figures of merit of practical interest. Our study may have significant implications for multiparameter quantum estimation problems, such as quantum metrology. Meanwhile, it may promote our understanding about the complementarity principle and uncertainty relations from the information theoretic perspective.Comment: 9 pages, 4 figures; titles changed and structure reorganise

Error-compensation measurements on polarization qubits

Systematic errors are inevitable in most measurements performed in real life because of imperfect measurement devices. Reducing systematic errors is crucial to ensuring the accuracy and reliability of measurement results. To this end, delicate error-compensation design is often necessary in addition to device calibration to reduce the dependence of the systematic error on the imperfection of the devices. The art of error-compensation design is well appreciated in nuclear magnetic resonance system by using composite pulses. In contrast, there are few works on reducing systematic errors in quantum optical systems. Here we propose an error-compensation design to reduce the systematic error in projective measurements on a polarization qubit. It can reduce the systematic error to the second order of the phase errors of both the half-wave plate (HWP) and the quarter-wave plate (QWP) as well as the angle error of the HWP. This technique is then applied to experiments on quantum state tomography on polarization qubits, leading to a 20-fold reduction in the systematic error. Our study may find applications in high-precision tasks in polarization optics and quantum optics.Comment: 8 pages, 3 figure