A performance simulation model of the PT6A-62 turboprop engine using the SIMULINK® was proposed to predict transient and steady state behaviors. This SIMULINK has some advantages such as user-friendly circumstance due to the GUI (Graphic User Interfaces) and ease in modification of the computer program. The SIMULINK model consists of subsystems to represent engine gas path components such as flight initial subsystem, compressor subsystem, burner subsystem, compressor turbine subsystem, power turbine, exhaust nozzle subsystem and integrator subsystem. In addition to these subsystems, there are search subsystems to search an appropriate operating point by scaling from the 2-D components look-up table, error matching subsystem to calculate the gas property precisely. In case of steady state validation, performance parameters analyzed by the proposed SIMULINK model were compared with the analysis results by commercial GASTURB program. In the validation of the transient model, the produced dynamic simulation results were compared with analysis results produced by a well-proved computer program using FORTRAN. In performance analysis of the PT6A-62 turboprop engine by the developed SIMULINK model, the steady state simulation was performed at off design points with altitude variation and part throttle, and the transient simulations with step fuel increases for accelerating the engine were carried out from 64% rpm (idle speed) to 94%rpm. In this investigation, the maximum error in all steady state off-design points in part load cases was within 7.33%. In case of transient analysis with different step fuel increases, the acceleration times using the SIMULINK model were well agreed with experimental values, and also the times calculated by the well proven FORTRAN program.

No abstract

Background: For the surgical treatment of cervical spondylotic myelopathy (CSM), anterior decompression with fusion or posterior decompression using microscopy has been used widely as the standard procedure, depending on the location of pathology and the surgeon's preference. Endoscopic anterior cervical discectomy and interbody fusion (E-ACDF) is a minimally invasive, effective surgical option for the management of CSM. The advantages of using endoscopy for anterior cervical discectomy and interbody fusion (ACDF) are better visualization of the operative field with the possibility of changing the angle of the endoscope. This reduces the damage to the normal anatomical structure. Although long-term follow-up results are needed to evaluate fusion rate and complication, this appears to be a safe and feasible alternative to conventional ACDF for CSM. In this article, we have described the surgical technique, summarized the endoscopic process to discuss its operative strategies, and reviewed the radiographic records, pre- and postoperatively. Material and Methods: This retrospective review study included 36 cases aged 37 to 65 years, with CSM at one segment. All of them underwent full E-ACDF from January 2018 to April 2021. All patients were followed up for 12 months after the procedure by outpatient interviews. The clinical outcomes were evaluated based on the Visual Analog Scale (VAS) of the arm, and Japanese Orthopedic Association (JOA) score with clinical data at preoperative, 3, and 12 months after the operation. Hirabayashi method was used to assess the neurological recovery after 12 months of operation. Radiological outcomes were evaluated using plain radiography and magnetic resonance imaging, computed tomography scan to evaluate disc height, cervical lordosis (Cobb's angle), and solid fusion. Results: The mean operation time was 150 min (range 120–170 min) and the average length of hospital stay was 2 ± 3 days. There was one case of immediate postoperative anterior neck hematoma, which required open revision surgery. There was no case of infection or damage to the anterior visceral organ. The mean VAS scores for arm pain and mean JOA scores after endoscopic ACDF were significantly improved compared with before the operation during the follow-up period. The recovery rate, which was evaluated by the Hirabayashi method, looked good enough to indicate well recovered postoperatively. The disc height changed from 5.2 mm preoperatively to 6.2 mm after immediate postoperative and 5.9 mm after 6 months (P < 0.01). Cervical lordosis as Cobb's angle between C2 and C7 was significantly improved compared to the preoperative one during the follow-up periods also. The bone fusion rate was 100% at 6 months after the operation, and there was no segmental instability. Conclusions: The present study demonstrates that E-ACDF is a minimally invasive and effective surgical option for the surgical management of CSM. Based on the present study, E-ACDF may potentially enable the avoidance of various shortcomings related to surgical approaches. Through a sort of preliminary investigation, the authors confirmed the feasibility of E-ACDF and presented comparable outcome results, which might dispel the safety concern because of only one complication of wound hematoma. Better-designed randomized controlled studies with larger sample sizes in longer-term follow-ups are strongly warranted.

Laminectomy and fusion were surgical options to decompress neural structures and provide more space for the spinal cord in a stenosis patient with severe leg pain and progressive neurologic signs, such as numbness and weakness. The evolution of endoscopic spinal surgery techniques has created advantages for patients who require a laminectomy. The authors present a unique technique for endoscopic access to the central and lateral recess pathology as a minimally invasive procedure, which provides a good visualization. We performed two cases of endoscopic spinal surgery for single-level and consecutive three-level lumbar spinal canal stenosis using an 8 mm outer diameter, 5.5 mm working channel, 10° angled lens spinal endoscopic system (percutaneous stenoscopic lumbar decompression, MaxMore Spine Company, Unterföhring, Germany). Optimized endoscopic drills, forceps, and Kerrison punch were used to remove bony pathology and ligamentum flavum under direct endoscopic visualization. The first case had a narrow canal space in the L4/L5 segment with severe numbness at the same dermatome and did not respond with adequate conventional treatment. The second case had three-level canal stenosis with severe back pain and leg weakness. The purpose of this paper is to describe the technique, the efficacy, and feasibility of unilateral endoscopic laminectomy and bilateral decompression via posterior approach in lumbar spinal canal stenosis. Moreover, in this article, we present the technical details on endoscopic procedures and the prevention of complications and management during operation for spinal canal stenosis.

No abstract