Platform Height Research Articles

Header Height Detection and Terrain-Adaptive Control Strategy Using Area Array LiDAR

During the operation of combine harvesters, the cutting platform height is typically controlled using manual valve hydraulic systems, which can result in issues such as delays in adjustment and high labor intensity, affecting both the quality and efficiency of the operation. There is an urgent need to enhance the automation level. Conventional methods frequently employ single-point measurements and lack extensive area coverage, which means their results do not fully represent the terrain’s variations in the area and are prone to local anomalies. Given the inherently undulating terrain of farmland during harvesting, a control strategy that does not adjust for minor undulations but only for significant ones proves to be more rational. To this end, a sine wave superposition model was established to simulate three-dimensional ground elevation changes, and an area array LiDAR was used to collect 8 × 8 data for the header height. The effects of mounds and stubble on the measurement results were analyzed, and a dynamic process simulation model for the solenoid valve core was developed to analyze the on/off delay characteristics of a three-position four-way electromagnetic directional valve. Moreover, a physical model of the hydraulic system was constructed based on the Simscape module in Simulink, and the Bang Bang switch predictive control system based on position threshold was introduced to achieve early switching of the electromagnetic directional valve circuit. In addition, an automatic control system for cutting platform height was designed based on an STM32 microcontroller. The control system was tested on the hydraulic automatic control test rig developed by Shanxi Agricultural University. The simulation and experimental results demonstrated that the control system and strategy were robust to output disturbances, effectively enhancing the intelligence and environmental adaptability of agricultural machinery operations.

Cytokine Response to Resistance Exercise in Children with Excess Fat and Prader-Willi Syndrome

Background: Tumor necrosis factor alpha (TNF-α) is a proinflammatory cytokine that is secreted from adipose tissue and macrophages; interleukin-6 (IL-6), secreted from adipose tissue, macrophages and skeletal muscle, has both proinflammatory and anti-inflammatory properties. Previous research showed excess adiposity leads to an increased concentration of both cytokines at rest while there is limited research on resistance exercise. Purpose: To compare IL-6 and TNF-α responses to resistance exercise in children with Prader-Willi Syndrome (PWS), a genetic cause for obesity, vs. children with normal fat mass (lean), or excess body fat (obesity) Methods: Nine children with PWS (11.4 ± 3.3 years, 45.6 ± 5.2% body fat), 11 lean children (9.2 ± 1.4 years, 18.6 ± 5.0% bodyfat), and 12 children with obesity (9.6 ± 1.3 years, 40.4 ± 5.4% body fat) participated. Children stepped onto an elevated platform wearing a weighted vest for 6 sets of 10 repetitions per leg (sets separated by 1 min of rest). Children with PWS, stepped to a platform height of 23.0 cm and wore a vest load that was computed as (20% of stature* 50% of lean body mass)/23.0 cm. For the controls, the platform height was 20% of the stature and the vest load was 50% of the lean body mass. Blood samples were obtained before (pre), immediately after (post), and during recovery from exercise (+15 and +60 min). Areas under the curve (AUC) were computed for IL-6 and TNF-α. Results: There was no group by time interaction for IL-6 ( p=0.378) but a group effect ( p=0.011) and a time effect ( p<0.001). Pairwise comparisons showed 60+ (1.065 ± 0.10 pg/mL) was higher than pre (0.660 ± 0.05 pg/mL), post (0.728 ± 0.06 pg/mL), and +15 (0.764 ± 0.066 pg/mL), p<0.001 for all. Children with PWS and children with obesity had higher IL-6 concentrations than lean children (0.943 ± 0.12 pg/mL and 0.951 ± 0.10 pg/mL vs. 0.519 ± 0.11 pg/mL, p≤0.038 for both). For TNF-α, there were no group by time interaction, time or group effects ( p≥0.420 for all). IL-6 AUC ( p=0.013) but not TNF-α AUC ( p=0.404) were different between groups. Children with PWS and children with obesity showed a higher IL-6 AUC than lean children (85.106 ± 41.81 pg/mL, 86.796 ± 33.60 pg/mL vs. 47.611 ± 21.00 pg/mL, p≤ 0.041 for both). Conclusion: There were no differences in IL-6 or TNF-α responses to exercise based on having PWS or having excess body fat in children. However, excess body fat was associated with higher IL-6 concentration and AUC. Peak concentrations for IL-6 were observed at 60 minutes after exercise similar to other studies. Potentially, IL-6 concentrations immediately post-exercise were not elevated because the exercise protocol was not of high intensity or long enough. Study funded by the US Army Medical Research and Material Command Contract W81XWH-08-1-0025 (DAR). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Scientific calculation and application of safety marking principles

In today's era, trains have become an indispensable mode of transportation for people, yet safety hazards are inevitable during the process of trains entering stations. To study these safety hazards and the principles behind the design of safety markings, we combine the Bernoulli Effect and the conservation of mechanical energy in fluids, taking into account factors such as a person's weight, volume, and distance from the train. We derive an expression that relates the pressure experienced by individuals to the train's speed, the train's cross-sectional area, the distance between the individual and the train, and the area of the individual subjected to force. By comparing this with the general friction force that corresponds to real-life situations, we find that the distances for safety markings provided by the national "Railway Technical Management Regulations" for high-speed train and dynamic train stations are reasonable: for speeds not exceeding 120km/h, the distance is 1000mm; for speeds over 120km/h but not exceeding 160km/h, the distance is 1500mm; and for speeds over 160km/h up to 200km/h, the distance is 2000mm, regardless of the platform height. Based on the factors affecting the safety markings on railway platforms, four practical safety recommendations are proposed.

The risk factors for injuries in parachuting and load exposure in the training of Chinese paratroopers.

Parachutists are generally recognized as a "high-risk" group among military personnel. However, the findings came mostly from data analysis without soldiers as subjects. This study aimed to investigate the injury prevalence in Chinese paratroopers on-site and determine the relationship between injury and risk factors encountered during parachuting and land-based training. This study consisted of a field study with questionnaire and an experiment on muscle load during the simulated training exercise of platform jumping with surface electromyography (EMG), in which 7230 paratroopers and 38 soldiers were involved respectively. Chi-square test was used for the injury rate analysis, ANOVA and t-test for comparison of EMG data, and logistic regression for the analysis of multiple factors. Taking both intensity and time into consideration, jump-years (J-yrs) was used as a complex indicator for exposure to parachuting. Either injury per 1000 jumps or injured persons per 100 soldiers were calculated as injury prevalence. The overall injury rate among Chinese parachutists was found to be 13.9 injuries per 1000 parachute jumps and 24.5% based on personnel. The person-based injury rate increased with the exposure level significantly (χ2 = 142.06, 2-sided, P < 0.05; trend test also significantly). Among the identified risk factors the uneven terrain was ranked as the most important one by logistic analysis. The EMG amplitude in MVE% increased with the platform height of all the 8 measured muscles and even reached 100% in 4 muscles, showing a high impact at landing. In addition, some characteristics of parachuting injury were also revealed by the injury type and site analysis. A dose-response relationship between parachuting and injury was observed significantly in the survey of Chinese paratroopers. Their injury rate was found to be relatively higher than the reported internationally. Landing impact as a critical point for injury seemed to be proved by the investigation and also the experiment with EMG measurement. It is suggested for future studies, to use the person-based injury rate, landing studied in work physiology and with consideration of different landing skills.

Perch height in broiler chickens at various ages: Frequency of use and behavioural time-budget

Chickens are motivated to perch, but the optimal height at which perching opportunities should be placed to facilitate access and use remains unclear. This study evaluated the ability of meat chickens to reach a perching platform set at different heights. Two experiments were carried out to test the hypothesis that perch height arrangement can contribute to its use during rearing. In the first experiment, the perching platform was placed at 0 cm (on the same level as the litter) during the first week of age; thereafter, it was alternated between 0, 10, 20, 30, and 40 cm in height within each day of the week for the remaining five weeks. In the second experiment, the platform height was alternated in 5 cm increments, hence between 0, 5, 10, 15, and 20 cm within each day of the week and tested over the same age period. The statistical model used included the fixed effects of age (in weeks), platform height and their interactions, and for the random effect of pen nested within treatment. In Experiment 1, chickens between weeks 2 and 6 of age used platforms more at 10 than 20 cm and did not reach the 30 and 40 cm heights. In Experiment 2, chickens used perches throughout the period of the 2nd to the 6th weeks of age but used higher perches (up to 20 cm) during the 3rd and 4th weeks of age. The platform height allowed perching behaviour when located at a maximum of 20 cm from the litter. Gradual 5 cm increases in perch height are likely to have been the reason for greater use in Experiment 2. In conclusion, chickens are motivated to use perches or elevated areas when placed at a height of up to 20 cm from floor level, and stepping them up in small increments of 5 cm may increase their use.

Characterization of semi-interpenetrating hydrogel based on Artemisia sphaerocephala Krasch Polysaccharide and cellulose nanocrystals crosslinked by ferric ions

Hydrogels are important bionic materials that can be used in a wide variety of biomedical applications. Artemisia sphaerocephala Krasch polysaccharide (ASKP) has been demonstrated to be crosslinked by ferric ions to form three-dimensional network. Here, a semi-interpenetrating network (semi-IPN) hydrogel based on ASKP and cellulose nanocrystals (CNC) crosslinked by ferric ions was fabricated and the effect of specific rod-like CNC was evaluated. It was found that the network of ASKP-Fe3+ hydrogel incorporated by CNC became denser along with the decreased pore diameter and the thickened pore wall. ASKP/CNC-Fe3+ hydrogel displayed an enhanced gel strength and water holding capacity. The dominant interaction of ASKP and CNC was hydrogen bonds proved by FTIR and QCM-D. Additionally, the elasticity of the semi-IPN hydrogel significantly increased along with the decrease of platform height in MSD curves based on particles tracking. These results may be caused by the fact that the rod-shaped CNC can be entangled with ASKP and prone to induce the orderly extension of ASKP chains, resulting in more hydroxyl and carboxyl groups exposed to be crosslinked with ferric ions. What's more, the stiff CNC located on the pore wall of ASKP-Fe3+ hydrogel can also strengthen the rigidity of network. Thus, this study suggests a new strategy to improve the properties of ASKP based hydrogel, and can be developed as a carrier to deliver iron ions.

FOSM-based updated consecutive modal pushover procedure (FUCMP) for seismic uncertainty quantification of jacket offshore platforms

In this paper, the updated consecutive modal pushover (UCMP) procedure is implemented in the framework of the first-order-second-moment (FOSM) approach, called herein the FUCMP procedure, to propose a simplified and fast method in order to quantify the effects of epistemic (modeling) uncertainties in jacket type offshore platforms (JTOP). The UCMP procedure can take into consideration the progressive changes in the modal characteristics of structures together with the higher mode effects in predicting the seismic demands of JTOPs. The proposed FUCMP procedure is applied to a case study JTOP structure for the ductility level seismic performance evaluation considering the uncertainties in the material mechanical properties, mass and weight, and geotechnical properties. The sensitivity analysis on the seismic drift demands along the platform height to the variability in different random variables is also conducted. To this end, the results of the UCMP procedure for the modified platform models created by different uncertain variables are compared with those of the mean deterministic model. Moreover, the results of the FUCMP procedure are compared with those from the nonlinear response history (NRH) analysis conducted using a suite of far-field earthquake ground motions. These records are scaled to the design abnormal level earthquake (ALE) response spectrum. The results indicate that the FUCMP procedure is successful in predicting the standard deviation of the seismic demands considering various sources of uncertainty. Conceptually, the proposed procedure can be applied for the probabilistic seismic demand evaluation of the other structural systems.

Through Running and Integration of Federal Railroad Administration and Federal Transit Administration Regulated Passenger Trains: A Path Toward Mixing Intercity, Commuter, Metro, and Light Rail on the Same Tracks

U.S. rail transit (subways, metros, and light rail) and Federal Railroad Administration (FRA) regulated heavy rail (commuter, intercity and regional rail) operate completely separately in revenue service. This necessitates transfers between the modes at terminals. While not unique to the U.S.A., its version of this practice is extreme and prevents the development of robust seamless rail networks. Especially in the post-Covid environment, this leaves commuter rail in search of a mission and rail transit isolated from suburbs. This paper discusses the statutory regulatory scheme that divides the two modes in the U.S.A. It will analyze the justification for the segregation and its history. Such issues include potential collisions, weight, crashworthiness, electrification, signaling, loading gauge, platform height, and operating practices. This paper concludes that the regulatory barrier preventing an FRA-regulated train from going onto a non-FRA railroad are surmountable. Running through trains between the FRA-regulated system and the rail transit network would enhance regional networks. The “Karlsruhe model” in Germany and the through running of regional trains onto the Tokyo subway network are two prime examples. Recent technological advances—such as dual mode battery multiple units, robust signaling systems such as Communications Based Train Control and Positive Train Control, and advanced car body designs able to deal with different loading gauges—make through running more practical. With little or no new right-of-way, it is possible to create far more useful rail networks. Potential shared networks at the conceptual level are discussed for Los Angeles, Seattle, Washington, D.C., Dallas, and Sacramento.

Elevated platforms with integrated weighing beams allow automatic monitoring of usage and activity in broiler chickens

Elevated platforms are a suitable possibility to enrich the environment of broiler chicken and, thus, improving their welfare. Early detection of health problems additionally contributes to an improved welfare of chickens and, at the same time, helps the farmer to optimize production efficiency. A prototype combined elevated platforms with weighing beams and an algorithm was developed to estimate number of chickens on the platform as well as their activity. To validate the prototype, during two consecutive trials, 1200 mixed-sex broiler chickens were kept for 35 days in 6 pens in total. In each pen, an elevated platform (height × length × width: 0.5 m × 4 m × 0.6 m), consisting of two rectangular steel frames and four load cells, was offered. Overall weight of broilers on the elevated platform was recorded continuously during the entire fattening period by the automatic weighing system. Algorithms were developed and implemented to estimate (i) daily mean weight of a single animal, (ii) number of animals on the platform, and two activity measures: (iii) movement on platform and (iv) number of platform changes from the weight recordings. To validate estimations, weight was recorded manually on 5 days throughout the trial and usage of elevated platforms was analysed via video records with scan sampling. From days 4 to 34, daily mean weight could be estimated using the proposed algorithm. Compared to manual weighing of a sample group at five days per pen, Spearman correlation coefficient was given by 0.9868 (p < 0.0001), and estimation error (RAE) was 11% on average. The number of chickens on the elevated platform could be approximated with deviations of about +19% and Spearman correlation of 0.97 (p < 0.0001) compared to video observations. An explanation for overestimation of animal number are occasional recalibration problems of the weighing system that resulted in measured weights being larger than actual weights. Furthermore, results of automatic approximation of usage behaviour and animal activity based on continuous recordings of the weighing system throughout days 4 to 34 of fattening are shown. In addition to providing an enrichment tool that could help farmers to control weight development of their livestock automatically and continually, first promising observations of anomalies due to heat and illness show that the proposed system could be used for early detection of animal welfare problems.

Effect of Structural Optimization of Scrubbing Cooling Rings on Vertical Falling Film Flow Characteristics.

In order to study the influence of the structural optimization of the scrubbing cooling ring in the scrubbing cooling chamber on the flow characteristics of the vertical falling film, the flow characteristics of the turbulent falling film in the rising section of the development region at different internal platform heights of the scrubbing cooling ring and a high Reynolds number were studied by FLUENT software. First, the correctness of the model was verified by the maximum error of simulation and experimental results of no more than 9.836%. Then, the distribution of liquid film thickness (δ), velocity (V), and turbulence intensity (Iz) at 0° of the tube in the axial direction x = 0–500 mm were calculated and obtained when the platform height (H) was 0–30 mm and the liquid film Reynolds number (Rel) = 1.1541 × 104–3.4623 × 104. The results showed that δ in the entrance region increased sharply due to the “jet” effect with solid wall constraints formed by the structure of the water inlet pipe and the scrubbing cooling ring. On the contrary, the liquid film in the fully developed region showed a stable fluctuation trend due to the weakening of the “jet” effect. When H = 30 mm, the change of δ was relatively stable and the change of Iz was small, indicating that this platform height is conducive to the stable and uniform distribution of the liquid film. In addition, when Rel < 1.1541 × 104, the liquid film was unstable due to the low flow rate and insufficient cohesion of the liquid film, but V increased slightly. In addition, with the increase of Rel, δ did not change significantly along the axial direction, that is, the Plateau–Rayleigh hindered the growth of δ. Finally, the empirical formula for δ applicable to Rel = 1.1541 × 104–3.4623 × 104 at the axial fixed position was fitted for the first time.

Does height-induced threat modulate shortening of reaction times induced by a loud stimulus in a lateral stepping and a wrist extension task?

The StartReact (SR) effect is the accelerated release of a prepared movement when a startling acoustic stimulus is presented at the time of the imperative stimulus (IS). SR paradigms have been used to study defective control of balance and gait in people with neurological conditions, but differences in emotional state (e.g. fear of failure) may be a potential confounder when comparing patients to healthy subjects. In this study, we aimed to gain insight in the effects of postural threat on the SR effect by manipulating surface height during a postural (lateral step) task and a non-postural (wrist extension) task. Eleven healthy participants performed a lateral step perpendicular to the platform edge, and 19 participants performed a wrist extension task while standing at the platform edge. Participants initiated the movement as fast as possible in response to an IS that varied in intensity across trials (80dB to 121dB) at both low and high platform height (3.2m). For the lateral step task, we determined anticipatory postural adjustments (APA) and step onset latencies. For the wrist extension task, muscle onset latencies were determined. We used Wilcoxon signed-rank tests on the relative onset latencies between both heights, to identify whether the effect of height was different for IS intensities between 103 and 118dB compared to 121dB. For both tasks, onset latencies were significantly shortened at 121dB compared to 80dB, regardless of height. In the lateral step task, the effect of height was larger at 112dB compared to 121dB. The absolute onset latencies showed that at 112dB there was no such stimulus intensity effect at high as seen at low surface height. In the wrist extension task, no differential effects of height could be demonstrated across IS intensities. Postural threat had a significant, yet modest effect on shortening of RTs induced by a loud IS, with a mere 3dB difference between standing on high versus low surface height. Interestingly, this effect of height was specific to the postural (i.e. lateral stepping) task, as no such differences could be demonstrated in the wrist extension task. This presumably reflects more cautious execution of the lateral step task when standing on height. The present findings suggest that applying stimuli of sufficiently high intensity (≥115dB) appears to neutralize potential differences in emotional state when studying SR effects.

Enhanced Weathering and Erosion of a Cohesive Shore Platform Following the Experimental Removal of Mussels

The organisms inhabiting intertidal platforms can affect their weathering and erosion rates. Research on biotic influences on platform integrity has traditionally emphasized the role of bioeroders (i.e., organisms that scrap or bore into platforms via mechanical and chemical means). Yet, recent studies illustrate that covers of sessile organisms on the surfaces of intertidal platforms can have bioprotective effects by reducing the efficacy of physical weathering and erosion agents. Eroding cliffs fronted by cohesive shore platforms are a pervasive feature along the continental Argentinean coastline (37–52°S). In this study, we investigated how mussel (Brachidontes rodriguezii) cover mediates weathering and erosion of a cohesive, consolidated silt platform at Playa Copacabana (5 km north of Miramar, Buenos Aires Province; 38° 14′ S, 57° 46′ W). By means of mussel removal experiments, we found that mussel cover attenuates variations in platform surface temperatures, enhances moisture retention during low tide, reduces rates of salt crystallization within the pores of the platform material, and attenuates hydrodynamic forcing on the platform surface. Mussel removal also led to a 10% decrease in surface hardness and a 2-mm reduction in platform height after 5 months. Collectively, our findings indicate that mussel beds limit substrate breakdown via heating-cooling, wetting-drying, and salt crystallization and provide some of the first experimental field evidence for the direct impacts of biotic cover on platform erosion. As intertidal platforms protect the cliffs behind from the hydraulic impact of waves, which may be enhanced with future sea-level rise, we posit that the protection of platforms by mussels indirectly moderates coastline retreat, especially on soft cohesive shores.

Investigation on the Effect of Platform Height on Smoke Characteristics of Fire Scenarios for Subway Stations

In this study, three full-scale experiments and a series of numerical simulations were conducted to investigate the influence of subway platform height and atrium ceiling height of subway stations on smoke control by mechanical exhausting systems. The smoke temperature variation with time, maximum temperature distribution, and smoke stratification were discussed. Results showed that the atrium had capacity to store smoke, especially at the early stage of smoke spread. However, the efficiency of smoke extraction did not increase simply with the rise in platform height and atrium ceiling height, and favorable smoke exhaust velocity was crucial for smoke elimination. The optimal smoke exhaust velocity was studied by numerical simulation and it was found that the area of smoke diffusion in subway stations with a higher platform was significantly smaller under the optimal smoke exhaust velocity. In addition, a prediction model of optimal smoke exhaust velocity with subway platform height was proposed. This study could provide on-site data and smoke spread characteristics for smoke control design, operation, and, significantly, guide safety evacuation of the exhaust system of subway stations.

Differential Neural Timecourse of Fast Mapping and Explicit Encoding of Novel Words: EEG and Behavioural Data

The StartReact (SR) effect is the accelerated release of a prepared movement when a startling acoustic stimulus is presented at the time of the imperative stimulus (IS). SR paradigms have been used to study defective control of balance and gait in people with neurological conditions, but differences in emotional state (e.g. fear of failure) may be a potential confounder when comparing patients to healthy subjects. In this study, we aimed to gain insight in the effects of postural threat on the SR effect by manipulating surface height during a postural (lateral step) task and a non-postural (wrist extension) task.Eleven healthy participants performed a lateral step perpendicular to the platform edge, and 19 participants performed a wrist extension task while standing at the platform edge. Participants initiated the movement as fast as possible in response to an IS that varied in intensity across trials (80 dB to 121 dB) at both low and high platform height (3.2 m). For the lateral step task, we determined anticipatory postural adjustments (APA) and step onset latencies. For the wrist extension task, muscle onset latencies were determined. We used Wilcoxon signed-rank tests on the relative onset latencies between both heights, to identify whether the effect of height was different for IS intensities between 103 and 118 dB compared to 121 dB.For both tasks, onset latencies were significantly shortened at 121 dB compared to 80 dB, regardless of height. In the lateral step task, the effect of height was larger at 112 dB compared to 121 dB. The absolute onset latencies showed that at 112 dB there was no such stimulus intensity effect at high as seen at low surface height. In the wrist extension task, no differential effects of height could be demonstrated across IS intensities.Postural threat had a significant, yet modest effect on shortening of RTs induced by a loud IS, with a mere 3 dB difference between standing on high versus low surface height. Interestingly, this effect of height was specific to the postural (i.e. lateral stepping) task, as no such differences could be demonstrated in the wrist extension task. This presumably reflects more cautious execution of the lateral step task when standing on height. The present findings suggest that applying stimuli of sufficiently high intensity (≥115 dB) appears to neutralize potential differences in emotional state when studying SR effects.

Numerical Simulation and Parameter Analysis of Electromagnetic Riveting Process for Ti-6Al-4V Titanium Rivet

Electromagnetic riveting process (EMR) is a high-speed impact connection technology with the advantages of fast loading speed, large impact force and stable rivet deformation. In this work, the axisymmetric sequential and loose electromagnetic-structural coupling simulation models were conducted to perform the electromagnetic riveting process of a Ti-6Al-4V titanium rivet, and the parameter analysis of the riveting setup was performed based on the sequential coupled simulation results. In addition, the single-objective optimization problem of punch displacement was conducted using the Hooke–Jeeves algorithm. Based on the adaptive remeshing technology adopted in air meshes, the deformation calculated in the structural field was well transferred to the electromagnetic field in the sequential coupled model. Thus, the sequential coupling simulation results presented higher accuracy on the punch speed and rivet deformation than the loose coupling numerical model. The maximum relative difference of electromagnetic force (EMF) on driver plate and radial displacement in the rivet shaft was 34.86% and 13.43%, respectively. The parameter analysis results showed that the outer diameter and the height of the driver plate had a significant first-order effect on the response of displacement, while the platform height, transition zone height, angle, and transition zone width of the amplifier presented a strong interaction effect. Using the obtained results on the optimal structural parameters, the punch speed was effectively improved from 6.13 to 8.12 m/s with a 32.46% increase. Furthermore, the displacement of the punch increasing from 3.38 to 3.81 mm would lead to an 80.55% increase in the maximum radial displacement of the rivet shaft. This indicated that the deformation of the rivet was efficiently improved by using the optimal rivet model.

Accuracy analysis of multi-baseline InSAR height inversion

Digital elevation model (DEM) is of great significance in commercial and scientific applications, and the accuracy of elevation inversion represents the quality of DEM. With reference to the height measurement accuracy formula of single-baseline interferometric SAR, the mathematical relations between elevation accuracy and platform height, lower viewing angle, target oblique distance, baseline strip number, baseline length and baseline roll angle are established, and the variation of elevation accuracy with system parameters (especially the number of base lines and baseline length) is quantitatively analyzed, and the optimal range of multi-baseline InSAR system parameters is obtained. It provides a theoretical basis for the optimal design of system parameters.

Validation of the Software-Hardware Complex “Rytm” for Measurement of the RR Intervals and Heart Rate Variability Analysis During Exercise and Recovery Period

The study purpose was estimation of the accuracy of RR time series measurements by SHC “Rytm” and validity of derived heart rate variability (HRV) indexes under physical loads and recovery period.&#x0D; Materials and methods. The participants were 20 healthy male adults aged 19.7 ± 0.23 years. Data was recorded simultaneously with CardioLab CE12, Polar RS800, and SHC “Rytm”. Test protocol included a 2 minute step test (20 steps per minute, platform height – 40 cm) with the next 3 minute recovery period. HRV indexes were calculated by Kubios HRV 2.1.&#x0D; Results. The RR data bias in the case of physical loads was -0.06 ms, it increased to 0.09-0.33 ms during the recovery period. The limits of agreement for RR data ranged from 3.7 ms to 22.8 ms, depending on the period of measurements and pair of compared devices. It is acceptable for the heart rate and HRV estimation. The intraclass correlation coefficients (0.62–1.00) and Spearman correlation coefficient (0.99) were high enough to suggest very high repeatability of the data. We found no significant difference (p &gt; 0.05) and good correlation (r = 0.94-1.00) between the majority of HRV indexes, calculated from data of Polar RS800 and SHC “Rytm” in conditions of physical loads (except for LF/HF ratio) and in the recovery period. The only one index (RMSSD) was different (p &lt; 0.05) in case of Polar RS800 and SHC “Rytm” data, obtained in the recovery period. The largest numbers of different HRV indexes have been found during the comparison of CardioLab CE12 and Polar RS800 – RMSSD, pNN50, and SD1. Correlation between HRV indexes (r = 0.81-1.00) was very high in all pairs of devices in all periods of measurements.&#x0D; Conclusions. The SHC “Rytm” appears to be acceptable for RR intervals registration and the HRV analysis during physical loads and recovery period.

Short-range clutter suppression method combining oblique projection and interpolation in airborne CFA radar

The airborne conformai array (CFA) radar's clutter ridges are range-modulated, which result in a bias in the estimation of the clutter covariance matrix (CCM) of the cell under test (CUT), further, reducing the clutter suppression performance of the airborne CFA radar. The clutter ridges can be effectively compensated by the space-time separation interpolation (STS-INT) method, which costs less computation than the space-time interpolation (STINT) method, but the performance of interpolation algorithms is seriously affected by the short-range clutter, especially near the platform height. Location distributions of CFA are free, which yields serious impact that range spaces of steering vector matrices are non-orthogonal complement and even no longer disjoint. Further, a new method is proposed that the short-range clutter is pre-processed by oblique projection with the intersected range spaces (OPIRS), and then clutter data after being pre-processed are compensated to the desired range bin through the STSINT method. The OPIRS also has good compatibility and can be used in combination with many existing methods. At the same time, oblique projectors of OPIRS can be obtained in advance, so the proposed method has almost the same computational load as the traditional compensation method. In addition, the proposed method can perform well when the channel error exists. Computer simulation results verify the effectiveness of the proposed method.

Research on the Parameter Design Method and System Simulation of Multimode Microwave Remote Sensors Operating in Scatterometer Modes

Multimode microwave remote sensors are a new type of radar system that operates in SAR (synthetic aperture radar), scatterometer, altimeter, and spectrometer modes in a time-sharing manner according to the current task scheduled on small satellites. High flexibility through mode switching is the outstanding advantage of this new microwave remote sensor. Two or more small satellites operating in different operation modes can be networked to perform observations synchronously to provide excellent remote sensing performance. This paper focuses on a method to determine the radar parameters of the scatterometer mode since the frequency band and the platform height of this new of kind sensor are determined according to the requirement of the SAR mode, and their values are evidently different from the values of current scatterometers in orbit. The proposed method systematically presents the complete steps and related formulae of the radar parameter design of scatterometers and determines the signal bandwidth by optimization. A system simulation method of the scatterometer mode is further studied to determine the wind field inversion error and thus evaluate the rationality of the parameter design results. In contrast to the existing methods, which directly add noise to the backscatter coefficients, our method simulates the noisy echo of the scatterometer and then retrieves the wind field by estimated backscatter coefficients from the noisy echo. The performed simulation shows that, by using the designed system parameters, the multimode microwave remote sensor obtains wind field inversion accuracy, resolution and swath width comparable to those of the HY-2 satellite and the QuikSCAT satellite.

Design of Wheel Chair Up Stairs at Station for Disability People

Intelligent wheelchairs are motorized resting media designed to help users with physical limitations, where an artificial control system is added or used to replace user controls. The aim is to reduce or eliminate the user's duty to drive a motorized wheelchair. At the station there are still many places that are still not accessible by persons with disabilities. As the difference between platform and train height, usually there are stairs that support to enter the train. Therefore the writer makes an innovation so that it can make it easier for people with disabilities to move up stairs in a wheelchair. The design of the wheelchair design uses a crawler type with the help of universal plates from Tamiya, the gearbox uses Twin Motor with a rotation ratio of 204: 1. Servo motor mounted on the seat which is supported by a gyro sensor as a counterweight to the chair when the position of the chair up or down. In the DC motor and servo PID method is added so that the motion changes can be smooth. PID is installed when testing the equilibrium results obtained a little stable oscillation at Kp = 0.27, Ki = 0.0004, and Kd = 0.0001, while when testing the speed obtained the most stable conditions at Kp = 2, Ki = 1, Kd = 0.25.