Adaptive entry guidance for the Tianwen-1 mission

To meet the requirements of the Tianwen-1 mission, adaptive entry guidance for entry vehicles, with low lift-to-drag ratios, limited control authority, and large initial state bias, was presented. Typically, the entry guidance law is divided into four distinct phases: trim angle-of-attack phase, range control phase, heading alignment phase, and trim-wing deployment phase. In the range control phase, the predictor—corrector guidance algorithm is improved by planning an on-board trajectory based on the Mars Science Laboratory (MSL) entry guidance algorithm. The nominal trajectory was designed and described using a combination of the downrange value and other states, such as drag acceleration and altitude rate. For a large initial state bias, the nominal downrange value was modified onboard by weighing the landing accuracy, control authority, and parachute deployment altitude. The biggest advantage of this approach is that it allows the successful correction of altitude errors and the avoidance of control saturation. An overview of the optimal trajectory design process, including a discussion of the design of the initial flight path angle, relevant event trigger, and transition conditions between the four phases, was also presented. Finally, telemetry data analysis and post-flight assessment results were used to illustrate the adaptive guidance law, create good conditions for subsequent parachute reduction and power reduction processes, and gauge the success of the mission.

Entry vehicle control system design for the Tianwen-1 mission

The entry vehicle for the Tianwen-1 mission successfully landed on the surface of Mars at 7:18 AM BJT on May 15, 2021. This successful landing made China the first country to orbit, land, and release a rover in their first attempt at the Mars exploration. The guidance, navigation, and control (GNC) system plays a crucial role in the entry, descent, and landing (EDL) phases. This study focused on the attitude control component of the GNC system design. The EDL phase can be divided into several sub-phases, namely the angle of attack control phase, lift control phase, parachute descent phase, and powered descent phase. Each sub-phase has unique attitude control requirements and challenges. This paper introduces the key aspects of designing attitude controllers for each phase. Furthermore, flight results are presented and analyzed.

Devising a method for improving the efficiency of artillery shooting based on the Markov model

This paper reports a method for improving the firing efficiency of an artillery unit that results in enhanced effectiveness. Given the modern use of artillery for counter-battery warfare, the effectiveness of shooting is not enough assessed by accuracy only. It is also necessary to take into consideration and minimize the time spent by the unit in the firing position and the consumption of shells to hit the target. It has been shown that in order to assess the effectiveness of an artillery shot due to the initial velocity of the projectile, the most rapid and simple means is to classify the quality of the shot by the acoustic field. A procedure for categorizing the shot has been improved by applying an automatic classifier with training based on a machine of support vectors with the least squares. It is established that the error in the classification of the effectiveness of the second shot does not exceed 0.05. The concept of the effectiveness of a single artillery shot was introduced. Under the conditions of intense shooting, there may be accidental disturbances in each shot due to the wear of the charging chamber of the gun, its barrel, and incomplete information about the powder charge. When firing involves disturbances, the firing of an artillery unit can be described by a model of a discrete Markov chain. Based on the Markov model, a method for improving the efficiency of artillery fire has been devised. The method is based on the identification of guns that produce ineffective shots. The fire control phase of the unit has been introduced. In the process of controlling the fire of the unit, such guns are excluded from further firing. A generalized criterion for the effectiveness of artillery firing of a unit, based on the convolution of criteria, has been introduced. It is shown that the devised method significantly improves the effectiveness of shooting according to the generalized criterion.

Empirical evaluation of energy profiles of thermally-efficient homes with smart energy systems and controls

Smart control technologies are beginning to be deployed in homes to optimise heating and alter the timing of domestic energy demand to enable residential demand side response (DSR). This paper presents before (baseline phase) and after (control phase) evaluation of the monitored indoor temperature and energy demand during the heating season in 10 new-build dwellings, each of which received a 5kWh electro-chemical battery and smart control to enable shifting of heating energy demand. The dwellings had air source heat pumps (ASHP) and 2kWp solar photovoltaic (PV) panels, and were located in a social housing estate in Barnsley, England. For eight dwellings, heat pump electricity use per heating degree day was found to decrease by 10% and narrow baseline peaks were suppressed during the control phase. Daily mean grid electricity import and heat pump electricity use in the peak period (4pm – 7pm) were measured as 4.0 kWh and 1.4 kWh during the control phase as compared to 3.8kWh and 1.3 kWh for the baseline phase. However the use of a flat tariff (single-rate) meant that battery charging-discharging capability was not fully utilised. Time-of-use tariff would further enhance cost savings associated with the change in the timing of energy demand.

Preliminary outcomes of combined treadmill and overground high-intensity interval training in ambulatory chronic stroke

Introduction: Locomotor high-intensity interval training (HIIT) is a promising intervention for stroke rehabilitation that typically involves bursts of fast treadmill walking alternated with recovery periods. However, overground translation of treadmill speed gains has been somewhat limited, some important outcomes have not been tested and baseline response predictors are poorly understood. This pilot study aimed to guide future research by assessing preliminary outcomes of combined overground and treadmill HIIT. Methods: Ten participants >6 months post stroke completed a multi-domain assessment battery before and after a 4-week no-intervention control phase, then again after a 4-week treatment phase involving 12 sessions of overground and treadmill HIIT. The primary analyses assessed relative changes in overground and treadmill walking speeds after HIIT, evaluated responsiveness of different outcome measures and estimated effects of baseline gait speed on treatment response. Results: Overground and treadmill gait function both improved during the treatment phase relative to the control phase, with overground speed changes averaging 61% of treadmill speed changes (95% CI: 33-89%). Moderate or larger effect sizes were observed for measures of gait performance, balance, fitness, cognition, fatigue, perceived change and brain volume. Participants with baseline comfortable gait speed <0.4 m/s had less absolute improvement in walking capacity but similar proportional and perceived changes. Discussion: Future locomotor HIIT studies should consider including: 1) both overground and treadmill training; 2) measures of cognition, fatigue and brain volume, to complement typical motor & fitness assessment; and 3) baseline gait speed as a covariate.

Oligomerized polyphenols in lychee fruit extract supplements may improve high-intensity exercise performance in male athletes: a pilot study

[Purpose] Excessive reactive oxygen species (ROS) induced by prolonged high-intensity exercise can cause structural and functional damage. Antioxidant polyphenol supplementation, which reduces ROS levels, may improve high-intensity exercise performance. We evaluated the effect of lychee fruit extract, which contains high levels of low-molecular-weight oligomerized polyphenols, on high-intensity exercise performance.[Methods] Ten male athletes were included in an open-label trial that consisted of control and intervention phases, with a 7-day washout period between phases. The participants were administered oligomerized lychee fruit extract for seven days, whereas no intervention was given in the control phase. High-intensity intermittent exercise and the Wingate test were performed. The power output, blood lactate levels, reactive oxygen metabolite levels, biological antioxidant potential, heart rate, and rate of perceived exertion were measured.[Results] The average power output was significantly higher in the intervention phase than in the control phase (P < 0.01), while the change in blood lactate levels was significantly lower in the intervention phase than in the control phase (P < 0.05). The average heart rate was significantly higher in the intervention phase than in the control phase (P < 0.05), without changing the rate of perceived exertion. Although there was no difference in reactive oxygen metabolite levels between the phase, the change in biological antioxidant potential was larger in the intervention phase than in the control phase (P = 0.06). The Wingate test showed no significant differences between the phase.[Conclusion] Short-term loading with oligomerized lychee fruit extract may increase performance during high-intensity intermittent exercise by improving metabolism.

Evaluating Improvement in Acute Stroke Management following Pre-hospital Initiation of Acute Stroke Service

Prehospital notification of the stroke team in alerting incoming acute stroke patient has been practiced in several countries worldwide. Currently this is not practiced in Malaysia. This study evaluates feasibility and impact to stroke team door to review time when prehospital notification is employed. Duration of case control study was between June 2018 to January 2019. Control phase consists of conventionally activating stroke team after in-hospital assessment by emergency medical officer. This was then followed by an intervention phase where on scene activation of stroke team was done by the Prehospital Emergency Care (PHC) staff. Training of PHC staff in recognising an acute stroke was based on identification of BE-FAST (Balance, Eyes, Face, Arm and Speech Test) abnormalities. The objectives were to compare the mean between two groups for acute stroke team review time, door to computerised tomography (CT) scan and door to thrombolysis time. Thirty-nine patients were analysed (control n=29, intervention n=10). Results were insignificant (p>0.05). Mean time in minutes for control phase vs. intervention phase was as follows: Door to stroke team review time, 25.96 + 39.16 vs. 15.9 + 13.14, door to CT scan was 43.04 + 40.00 vs. 25.8 + 11.35. Only 3 patients underwent thrombolytic therapy during study period. Limitation was non-parametric data with lack of number of acute stroke cases responded during the intervention period. With continual training of pre-hospital staff in detecting acute stroke, feasibility can be improved.

Task-specific movement training improves kinematics and pain during the Y-balance test and hip muscle strength in females with patellofemoral pain

ObjectivesTask-specific movement training is a proposed intervention for patellofemoral pain aimed to optimise movement during daily tasks. Focused, progressive task practice emphasising optimal limb alignment may yield improvements in performance-based function and hip muscle strength, and transfer learnt movement patterns to untrained tasks. The purpose of this study was to determine if task-specific movement training improves performance-based function (composite score, movement, pain during movement) in an untrained task. Our secondary purpose was to test whether hip muscle strength improved following the movement training intervention.MethodsThis study was a secondary analysis of a prospective, non-randomised, within-group, double-baseline study. Twenty-three females with patellofemoral pain underwent task-specific movement training two times/week for 6 weeks. Outcomes were collected at three time points: enrolment (baseline), 6 weeks (preintervention) and 12 weeks (postintervention). A repeated measures analysis of variance tested whether the change during the intervention phase was greater than the change during the control phase. Y-balance composite score, hip and knee kinematics and pain during the Y-balance test were primary outcome measures; strength of the hip lateral rotator, abductor and extensor muscles was a secondary outcome measure.ResultsThe change in composite score for the Y-balance test was not statistically significantly different between the intervention and control phases (p=0.16). The change during the intervention phase exceeded the change during the control phase for hip and knee kinematics and pain during the Y-balance test, with all variables improving (p<0.0001). The change during the intervention phase was greater than the control phase for hip muscle strength, with all variables improving (p<0.04).ConclusionAlthough the Y-balance test composite score did not improve, performance-based function during an untrained task, measured by movement and pain during the test, improved following task-specific movement training. Hip muscle strength improved, despite no focused muscle strengthening.Level of evidenceLevel II.