No abstract

In order to solve the dilemma between the smaller pressure loss and the larger flow measurement signal in traditional throttle flowmeters, a throttle structure with the inner-outer tube was designed and analyzed. The mathematical relationship model deduced from hydrodynamics showed there were three major parameters to determine the designed throttle structure. Furthermore, the optimal results were achieved by combining orthogonal test design and computational fluid dynamics by taking the ratio of differential pressure of inner-outer tube divided by that of anterior-posterior tube as the optimization goal. Finally, the simulation results with the best level parameters showed that the differential pressure of the anterior-posterior throttle could remain not only the smaller value among other parameters with the same structure of inner-outer tube. On the other hand, it was about one order magnitude less than differential pressure of V-cone flowmeter in the similar installation conditions with the flow velocity varying from 0.5 to 3.0 m/s. The designed inner-outer tube flowmeter can not only save manufacture costs, but also avoid the large sensitivity of pressure sensors, which may lead to a broader application in chemical and petrochemical enterprises.

As a kind of semiconductor with wide band gap, MnS has received wide attention for supercapacitors. However, its electrochemical performance is often unsatisfactory. A practical solution to the poor energy...

A novel mesoporous urchin‐like Co−Ni−Fe ternary hydroxide (CoNiFe−TH) assembled by a large amount of nanoneedles on nickel foam was successfully prepared through a facile one‐step hydrothermal method. The mesoporous urchin‐like CoNiFe−TH nanoneedle electrode has a high specific capacitance of 1318.52 F g−1 at a current density of 1 A g−1 in a three‐electrode system. Besides, the electrode exhibits an excellent cycling stability with 63.3 % specific capacitance retention and almost 100 % Coulombic efficiency during 1000 cycles of a charge‐discharge process at a current density of 5 A g−1. The excellent electrochemical performance of the electrode is due to the unique mesoporous urchin‐like CoNiFe−TH nanoneedles structures with more active reaction sites and polymetallic synergistic effects, which can facilitate the faradic reaction process to improve the electrochemical performance. The current synthesis method can be used for the preparation of other ternary transition metal hydroxides as electrode materials for supercapacitors.

Summary A reduced‐order model (ROM) is presented based on Fourier method for flow to predict aerodynamic forces of blades subjected to periodic time‐varying upstream wakes. In the method, a time‐varying wake is decomposed into harmonic waves by fast Fourier transformation. Using the Fourier method for flow and neglecting the cross‐coupling between harmonics, the aerodynamic forces caused by the wake are represented by a linear combination of harmonics with the same frequencies as the wake. The coefficients of the aerodynamic force harmonics are interpolated at the per‐fitted curves of the normalized Fourier coefficients (coefficients of aerodynamic forces harmonics corresponding to a unit simple harmonic excitation)–frequency relationship. A blade example is used to show the ability of the proposed method. The results indicate that the ROM method can predict the aerodynamic forces of blades caused by wakes efficiently and accurately. The amplitude levels of wakes have a linear impact on the accuracy of the ROM. Neglecting the higher‐order cross‐coupling between the harmonics in the ROM method is acceptable.