This study examines the effects of varying processing parameters, including pouring temperature (590, 610, 630 °C), holding time (10, 15, 20 s), and magnesium addition (0.5, 1, 1.5 wt.
This Speaking Out attends to the opacity and injustice of scientific manuscript evaluation. Its focus is upon the embeddedness of editors, reviewers and authors in a moral order conditioned by an asymmetrical structure of power relations that is sustained by deference and secrecy. Attention is given to the shortcomings of complaints and appeals procedures that currently provide the principal, non-independent means of safeguarding science by interrogating the adequacy of manuscript evaluation processes. To transform the structure of power relations, and thereby strengthen the "gold standard" of peer review, some ways of increasing the openness and accountability of manuscript evaluation are proposed.
Floating offshore wind turbines(FOWTs)are extensively utilized in offshore energy development.However,FOWTs are vulnerable to pitch motion,and high-frequency pitch motion may result in structural damage,equipment failure,and associated hazards.To suppress the undesired pitch motion of FOWTs,this paper presents an innovative Rotating Plates Tuned Mass Damper(RPTMD)system designed according to the natural frequency characteristics and spatial features of FOWTs.The motion equations of the RPTMD-FOWT system are established based on the TMD similarity principle.Through numerical modeling,parameters including rotating plate size,tuning ratio,and damping ratio are systematically examined.Furthermore,a comprehensive three-dimensional motion response model of floating body-wave-mooring interaction is developed to assess the RPTMD system's effectiveness in FOWT motion control under extreme loading conditions.The motion suppression effect is evaluated using displacement peaks and displacement mean-square responses of the main mass.The energy dissipation characteristics of RPTMD are quantitatively analyzed through damping moments.Results indicate that the RPTMD exhibits optimal damping capability under resonant excitation,with a rotational inertia ratio of 0.7%achieving pitch suppression efficiency of 38.92%and heave suppression efficiency of 31.12%.
In this paper, a novel end-plate joint was proposed, which was designed to implement the three-stage control concept against progressive collapse. It delays the collapse process by presetting friction force, special-shaped bolt hole and adding composite cushion at the bottom of bolt hole. The anti-collapse mechanism and control strategy of the structure under the influence of multiple factors were studied by means of beam-column subassembly test and numerical and theoretical analysis. The results show that the initial stiffness of the load-displacement curve of the new bolted joint subassembly is small, but the yield plateau is long and the failure load is large. The curve has obvious three-stage characteristics, and the catenary mechanism is fully developed. That is, the collapse process of the structure was divided into three stages: “small impact”, “medium impact” and “large impact”. On this basis, the corresponding three-stage anti-collapse control strategy was proposed and verified by finite element model. During the “small impact” stage, mainly based on the reasonable initial stiffness requirements, the friction coefficient is changed through the coating of the steel plate, meanwhile the bolt preload is adjusted to determine the preset friction force of the joint, so as to meet the “small impact immovable” requirement. During the “midium impact” stage, the preset extrusion force is mainly determined by changing the ratio of the “jammed diameter” to the bolt diameter based on the reasonable slip distance and the reasonable extrusion force, so as to meet the requirement that the “midium impact stuck”. In the stage of “final impact”, the preset structure's ability to resist progressive collapse is determined by changing the performance of the composite cushion at the bottom of the bolt hole, according to the requirements of reasonable progressive collapse resistance of the structure, so as to realize the requirements of “final impact non-collapse” or delay the process of progressive collapse of the structure. The results of substructure model test and finite element analysis show that the proposed three-stage anti-continuous collapse control strategy was easy to implement, and the mechanism and capacity of anti-continuous collapse were improved obviously, which has a good research and application prospect.
We investigate properties of the bijective Burrows-Wheeler transform (BBWT). We show that for any string w, a bidirectional macro scheme of size O ( r_B ) can be induced from the BBWT of w, where r_B is the number of maximal same-symbol runs in the BBWT. We also show that r_B = O ( z log ^ 2 n ) , where n is the length of w and z is the number of Lempel-Ziv 77 factors of w. Then, we show a separation between BBWT and BWT by a family of strings with r_B = Ω ( log n ) but having only r= 2 , where r is the maximal same-symbol runs in the standard Burrows–Wheeler transform (BWT). However, we observe that the smallest r_B among all cyclic rotations of w is always at most r . While computing an optimal rotation yielding the smallest r_B in o ( n ^ 2 ) time remains an open problem, we show how to compute the Lyndon factorizations – a component for computing BBWT – of all cyclic rotations in O(n) time using right and left Lyndon trees. We also show that the optimal rotations can be computed in Õ (nh) time, where h is the (maximum) height of the two Lyndon trees which can vary from log n to n. Furthermore, we conjecture that we can transform two strings having the same Parikh vector to each other by BBWT and rotation operations, and prove this conjecture for the case of binary alphabets and permutations.
