Rapid SINS Two-Position Ground Alignment Scheme Based on Piecewise Combined Kalman Filter and Azimuth Constraint Information.

The accuracy and rate of convergence are two important performance factors for initial ground alignment of a strapdown inertial navigation system (SINS). For navigation-grade SINS, gyro biases and accelerometer offsets can be modeled as constant values during the alignment period, and they can be calibrated through two-position ground alignment schemes. In many situations for SINS ground alignment, the azimuth of the vehicle remains nearly constant. This quasi-stationary alignment information can be used as an augmented measurement. In this paper, a piecewise combined Kalman filter utilizing relative azimuth constraint (RATP) is proposed to improve the alignment precision and to reduce the time consumption for error convergence. It is presented that a piecewise time-invariant linear system can be combined into a whole extended time-invariant linear system so that a piecewise combined Kalman filter can be designed for state estimation. A two-position ground alignment algorithm for SINS is designed based on the proposed piecewise combined Kalman filter. Numerical simulations and experimental results show its superiority to the conventional algorithms in terms of accuracy and the rate of convergence.

Size-Dependent Structural Properties of a High-Nb TiAl Alloy Powder.

TiAl-based alloys are promising light weight structural materials for high temperature applications in the field of aerospace. Recently, fabrication technologies starting from powders including powder metallurgy and additive manufacturing have been developed to overcome the difficulties in the processing, machining and shaping of TiAl-based alloys. Spherical alloy powders with different particle size distributions are usually used in these fabrication techniques. The purpose of this study is to reveal the size-dependent structural properties of a high-Nb TiAl powder for these fabrication technologies starting from powders. A high-Nb TiAl pre-alloyed powder with nominal composition of Ti-48Al-2Cr-8Nb (at. %) was prepared by the electrode induction melting gas atomization (EIGA) method. The phase structure and morphology of the as-atomized powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The size-dependent structural changes of the as-atomized powders with different sizes were studied by differential scanning calorimetry (DSC) and in situ high temperature XRD. It was found that with decreasing the powder size, the content of the γ-TiAl phase decreases and the α2-Ti3Al phase increases. The α2-Ti3Al to γ-TiAl phase transformation was found in the temperature range of 600-770 °C. Based on the present work, the structural characteristics of TiAl powders are strongly dependent on their particle size, which should be considered in optimizing the process parameters of TiAl alloys fabricated from powders.

Effect of beraprost on pulmonary hypertension due to left ventricular systolic dysfunction.

Beraprost is used to treat peripheral chronic arterial occlusive disease. However, the efficacy and safety of beraprost in patients with pulmonary hypertension (PH) due to left ventricular systolic dysfunction (PH-HFrEF) remains unknown. The primary objective of this study was to determine the effects of beraprost on PH-HFrEF.We prospectively recruited patients with PH-HFrEF as determined by echocardiography and right cardiac catheterization. Beraprost sodium was given orally (1 µg/kg/d) added to the usual treatment, and patients were evaluated at 1-year follow-up.Twenty-five patients were recruited with baseline systolic pulmonary artery pressure (PAP) of 49.5 ±â€Š10.8 mm Hg. Systolic PAP results at 3, 6, 9, and 12 months were 39.1 ±â€Š8.1, 30.4 ±â€Š5.2, 27.7 ±â€Š3.0, and 27.0 ±â€Š4.7 mm Hg, respectively, which were all significantly lower than systolic PAP at baseline (P < .05). Left ventricular ejection fraction results at 6 months (43.5 ±â€Š7.0%), 9 months (47.0 ±â€Š5.5%), and 12 months (48.2 ±â€Š4.8%) were significantly higher than at baseline (34.7 ±â€Š9.2%) (P < .05). Six-minute walking distance at 3 months (282.8 ±â€Š80.6 m), 6 months (367.1 ±â€Š81.2 m), 9 months (389.8 ±â€Š87.1 m), and 12 months (395.7 ±â€Š83.4 m) increased with time, and all were significantly higher than baseline (190.1 ±â€Š75.5 m) (P < .05). One patient developed atrial fibrillation and recovered to sinus rhythm after intravenous administration of amiodarone. There were no instances of cardiac-related death, severe bleeding, or severe impairment of liver function.Routine oral administration of beraprost sodium added to the usual treatment may improve cardiopulmonary hemodynamics and exercise capacityin patients with PH-HFrEF.

Prognostic Value of Ventricular Wall Motion Score and Global Registry of Acute Coronary Events Score in Patients With Acute Myocardial Infarction.

OBJECTIVE: The aim of this study was to evaluate the prognostic values of ventricular wall motion score (WMS) and Global Registry of Acute Coronary Events (GRACE) score in patients with acute myocardial infarction (AMI) in a 12-month single-center prospective cohort. MATERIALS AND METHODS: Consecutive inpatients diagnosed with AMI in the Department of Cardiology of The Second Affiliated Hospital of Soochow University from September 2012 through March 2015 were enrolled in this study. Echocardiography was issued to all subjects to calculate WMS within 24 hours after admission, and GRACE score of each patient was obtained simultaneously. During a 12-month follow-up period, all major adverse cardiac events (MACE) were recorded. RESULTS: After 12 months of observation, 124 of 635 patients with AMI developed MACE. The WMS (23.70 ± 3.80 versus 20.47 ± 3.25) and GRACE score (185.59 ± 45.16 versus 152.19 ± 36.51) were significantly higher in patients with MACE than those without MACE (P < 0.05). Survival analysis using Cox regression revealed that both WMS (95% CI: 1.082-1.184, P < 0.05) and GRACE score (95% CI: 1.010-1.021, P < 0.05) independently predicted MACE. The receiver operating curve curve analysis showed that the area under curve of WMS, GRACE score and the combination of WMS and GRACE score were 0.768 (P < 0.05), 0.718 (P < 0.05) and 0.812 (P < 0.05), respectively. CONCLUSIONS: WMS and GRACE score were independent predictors of MACE in patients with AMI in 12-month follow-up, and the combined application of WMS and GRACE score can significantly improve the predictive value.

[Therapeutic effect evaluation of artificial hip replacement].

OBJECTIVE: To discuss the indications and other related issues of artificial hip replacement. METHOD: A retrospective analysis was conducted in 37 cases with artificial hip replacement with complete follow-up data treated between 1996 and 2001. RESULTS: The patients were followed up for 1 to 5 years. The average Harris score of these patients was 51 preoperatively and 82 postoperatively, and 10 of them had excellent, 23 good, 2 acceptable and 2 poor outcomes. Such complications as prothesis mobilization (2 cases), joint dislocation (1 case), prothesis pricking through the femur (1 case) and infection (3 cases) occurred after the operation. Embolism in the deep veins of the lower limb, sciatic nerve injury or severe general complications were not observed. CONCLUSION: Proper evaluation of the indications, careful preoperative preparation, proficient operative skills, and good postoperative treatment can ensure favorable outcome of artificial hip replacement with minimum complications.