严格逆向过程的捷联惯导快速回溯对准

回溯对准是利用高性能计算机反复进行正向和逆向导航解算来实现惯导系统的初始对准。对捷联惯导系统回溯参数辨识对准技术进行了研究,首次将严格逆向过程用在常规回溯对准中,其逆向过程不采用常规的近似解算,而是严格由正向过程的终点递推至起点,这可有效缩短惯导姿态失准角的估计时间,从而可相应提高捷联惯导在相同对准精度下的对准速度。最后,利用光纤陀螺捷联惯导系统进行了离线对准试验。结果表明,该对准方法的对准时间比常规回溯对准法缩短了1/3以上,证明了该对准方法的正确性、可行性。     

Effect of fluid and salt supplementation on body hydration of athletes during prolonged hypokinesia

Body hydration decreases significantly during hypokinesia (HK) (diminished movement), but little is known about the effect of fluid and salt supplements (FSS) on body hydration during HK. The aim of this study was to measure the effect of FSS on body hydration during HK. Studies were done during 30 days pre HK period and 364 days HK period. Thirty male athletes aged 24.5 +/- 6.6 yr were chosen as subjects. They were equally divided into three groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS) and supplemented hypokinetic subjects (SHKS). Hypokinetic subjects were limited to an average walking distance of 0.7 km day-1. The SHKS group took daily 30 ml of water/kg body weight and 0.1 g of sodium chloride (NaCl)/kg body weight. Control subjects experienced no changes in their professional training and routine daily activities. Plasma volume (PV), urinary and plasma sodium (Na) and potassium (K), plasma osmolality, plasma protein, whole blood hemoglobin (Hb) and hematocrit (Hct), plasma renin activity (PRA) plasma aldosterone (PA) levels, physical characteristics, food and fluid intakes were measured. Plasma osmolality, plasma protein, urinary and plasma Na and K, whole blood Hct and Hb, PRA and PA levels decreased significantly (p < or = 0.01), while PV and body weight increased significantly (p < or = 0.01) in the SHKS group when compared with the UHKS group and did not change when compared with the UACS group. Plasma osmolality, plasma protein, urinary and plasma Na and K, PRA and PA, whole blood Hb and Hct levels increased significantly (p < or = 0.01), while PV body weight, food and fluid intakes decreased significantly (p < or = 0.01) in UHKS group when compared with the SHKS and UACS groups. The measured parameters did not change in the UACS group when compared with their baseline control values. It was shown that during HK body hydration decreased significantly, while during HK and FSS body hydration increased significantly. It was concluded that daily intake of FSS prevents the decrease of PV and blunts the increase of activity of the PRA and PA during prolonged HK.     

Fluid and salt supplementation effect on body hydration and electrolyte homeostasis during bed rest and ambulation

Bed rest (BR) induces significant urinary and blood electrolyte changes, but little is known about the effect of fluid and salt supplements (FSS) on catabolism, hydration and electrolytes. The aim was to measure the effect of FSS on catabolism, body hydration and electrolytes during BR.

Studies were done during 7 days of a pre-bed rest period and during 30 days of a rigorous bed rest period. Thirty male athletes aged, 24.6±7.6 years were chosen as subjects. They were divided into three groups: unsupplemented ambulatory control subjects (UACS), unsupplemented bed rested subjects (UBRS) and supplemented bed rested subjects (SBRS). The UBRS and SBRS groups were kept under a rigorous bed rest regime for 30 days. The SBRS daily took 30 ml water per kg body weight and 0.1 sodium chloride per kg body weight.

Plasma sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg) levels, urinary Na, K, Ca and Mg excretion, plasma osmolality, plasma protein level, whole blood hemoglobin (Hb) and hematocrit (Hct) level increased significantly (p≤0.05), while plasma volume (PV), body weight, body fat, peak oxygen uptake, food and fluid intake decreased significantly (p≤0.05) in the UBRS group when compared with the SBRS and UACS groups. In contrast, plasma and urinary electrolytes, osmolality, protein level, whole blood Hct and Hb level decreased significantly (p≤0.05), while PV, fluid intake, body weight and peak oxygen uptake increased significantly (p≤0.05) in the SBRS group when compared with the UBRS group. The measured parameters did not change significantly in the UACS group when compared with their baseline control values.

The data indicate that FSS stabilizes electrolytes and body hydration during BR, while BR alone induces significant changes in electrolytes and body hydration. We conclude that FSS may be used to prevent catabolism and normalize body hydration status and electrolyte values during BR.     

一种改进型光纤陀螺惯导系统单轴旋转调制方案

在常规单轴两位置旋转调制方案基础上,提出了一种改进型光纤陀螺惯导系统单轴旋转调制方案,该方案深入研究了载体航向角变化时,通过优选惯性测量组合(IMU)的旋转停止位置,实现了比常规调制方案更好的导航误差自补偿效果.通过理论推导和仿真验证,证明了本方案的有效性、可行性.     

Biochemical and hemodynamic changes in normal subjects during acute and rigorous bed rest and ambulation

Rigorous bed rest (RBR) induces significant biochemical and circulatory changes. However, little is known about acute rigorous bed rest (ARBR). Measuring biochemical and circulatory variables during ARBR and RBR the aim of this study was to establish the significance of ARBR effect. Studies were done during 3 days of a pre-bed rest (BR) period and during 7 days of ARBR and RBR period. Thirty normal male individuals aged, 24.1 +/- 6.3 years were chosen as subjects. They were divided equally into three groups: 10 subjects placed under active control conditions served as unrestricted ambulatory control subjects (UACS), 10 subjects submitted to an acute rigorous bed rest served as acute rigorous bed rested subjects (ARBRS) and 10 subjects submitted to a rigorous bed rest served as rigorous bed rested subjects (RBRS). The UACS were maintained under an average running distance of 9.7 km day-1. For the ARBR effect simulation, ARBRS were submitted abruptly to BR for 7 days. They did not have any prior knowledge of the exact date and time when they would be asked to confine to RBR. For the RBR effect simulation, RBRS were subjected to BR for 7 days on a predetermined date and time known to them right away from the start of the study. Plasma renin activity (PRA), plasma cortisol (PC), plasma aldosterone (PA), plasma and urinary sodium (Na) and potassium (K) levels, heart rate (HR), cardiac output (CO), and arterial blood pressure (ABP) increased significantly, and urinary aldosterone (UA), stroke volume (SV) and plasma volume (PV) decreased significantly (p<0.05) in ARBRS and RBRS as compared with their pre-BR values and the values in UACS. Electrolyte, hormonal and hemodynamic responses were significantly (p<0.05) greater and occurred significantly faster (p<0.05) during ARBR than RBR. Parameters change insignificantly (p>0.05) in UACS compared with pre-BR control values. It was concluded that, the more abruptly muscular activity is restricted in experimental subjects while they are very active, the greater hemodynamic and biochemical change there is and probably in individuals whose muscular activity is abruptly terminated after an accident or sudden illness.     

单轴旋转式光纤陀螺惯导系统误差特性研究

通过对单轴旋转式光纤陀螺惯导系统误差特性进行研究,从理论上分析了旋转对系统中各个误差因素的影响。由分析结果知旋转调制对光纤陀螺输出的高频随机噪声不具有补偿效果;陀螺安装误差对导航系统精度的影响主要表现为与旋转运动之间耦合产生的周期性误差;由于单轴旋转需要引入规律性的旋转运动,不恰当的旋转方式会导致系统误差的放大。最后对以上结论进行了仿真研究和试验验证。     

光纤陀螺SINS大失准角下快速初始对准技术

针对光纤陀螺(FOG)捷联惯导系统(SINS)初始对准过程中存在大姿态失准角的情况,本文建立了基于欧拉平台误差角的SINS非线性误差模型,给出了一种简化的UKF滤波方法并将其运用到光纤陀螺SINS初始对准中,在静基座大方位失准角条件下,分别采用传统闭环卡尔曼滤波和闭环UKF非线性滤波方法进行初始对准仿真研究,结果表明在对准精度要求相同时,后者在对准速度方面具有明显优势。