In five-axis machine tools, a rotary table is often used as a means for providing rotational motion and supporting the workpiece. Its rigidity, precision and carrying capacity is directly related to the machining ability and the accuracy of the NC machine tool. Traditional rotary table design is normally performed by teams, each with expertise in a specific discipline, which causes excessive iterations and cannot provide users with products of reliable working performance and bearing capacity. To achieve an optimal design with less cost and better performance, this paper considers the mutual interaction of hydrostatics and structure disciplines involved in the design of hydrostatic rotary tables, and a sensitivity-based multidisciplinary optimal design procedure of a hydrostatic rotary table is proposed. Sensitivity analysis is adopted to identify the key design parameters that have a major influence on the performance of rotary tables to improve the convergence of optimization process. The constrained multi-objective optimization problem is solved by using a particle swarm optimization approach. A hydrostatic rotary table of a five-axis heavy duty machine tool is selected as an illustration example. The results show that the proposed method can realize the multidisciplinary optimization resulting in a rotary table of good rigidity and bearing capacity.
Background We assess the effects of standard decompressive craniectomy with stepwise decompression of the intracranial compartment on the postoperative neurologic function, hemodynamics, and Glasgow Outcome Scale (GOS) score of patients with severe traumatic brain injury (sTBI).
Methods One hundred sTBI patients admitted from July 2017 to February 2019 were enrolled and randomly divided into step and standard groups (n = 50) using a random number table. The standard group received traditional standard decompression during surgery, while the step group underwent multistep decompression during surgery. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were measured immediately after surgery (T0), 3 hours after surgery (T1), 6 hours after surgery (T2), and 12 hours after surgery (T3). The postoperative Glasgow Coma Scale (GCS) score, neurologic function deficit score, and GOS score were evaluated.
Results After treatment, the excellent/good rate of neurologic function improvement and GCS and GOS scores of the step group significantly exceeded those of the standard group (p < 0.05). Compared with the standard group, the HR, SBP, DBP, and MAP decreased significantly in the step group at T1, T2, and T3 (p < 0.05).
Conclusion Standard decompressive craniectomy under multistep decompression can markedly improve the neurologic function, hemodynamics, and prognosis of patients.
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