Force Air Research Articles

Design of an Adaptive Fixed-Time Fast Terminal Sliding Mode Controller for Multi-Link Robots Actuated by Pneumatic Artificial Muscles

Pneumatic artificial muscles (PAMs) are flexible actuators that can be contracted or expanded by applying air pressure. They are used in robotics, prosthetics, and other applications requiring flexible and compliant actuation. PAMs are basically designed to mimic the function of biological muscles, providing a high force-to-weight ratio and smooth, lifelike movement. Inflation and deflation of these muscles can be controlled rapidly, allowing for fast actuation. In this work, a continuum mechanics-based model is developed to predict the output parameters of PAMs, like actuation force. Comparison of the model results with experimental data shows that the model efficiently predicts the mechanical behaviour of PAMs. Using the actuation force–air pressure–contraction relation provided by the proposed mechanical model, a dynamic model is derived for a multi-link PAM-actuated robot manipulator. An adaptive fixed-time fast terminal sliding mode control is proposed to track the desired joint position trajectories despite the model uncertainties and external disturbances with unknown magnitude bounds. Furthermore, the performance of the proposed controller is compared with an adaptive backstepping fast terminal sliding mode controller through numerical simulations. The simulations show faster convergence and more precise tracking for the proposed controller.

Quantifying the Impact of Sustained Acceleration on Critical Care Transport Medical Equipment

ABSTRACT Introduction Military and commercial stakeholders are investing to explore the use of hypersonic aircraft and orbital spacecraft to transport cargo, medical supplies, passengers, and casualties. These vehicle platforms require periods of sustained acceleration, but to date, these dynamic forces have not been comprehensively considered in the environment of critical care patient movement because injured patients and advanced aeromedical evacuation (AE) equipment are rarely subjected to these conditions. While military AE equipment does undergo crash hazard acceleration testing, equipment functionality during or after sustained acceleration remains to be evaluated. This study was performed to fill that knowledge gap. Materials and Methods AE equipment currently used by the U.S. Air Force and Critical Care Air Transport Teams (ZOLL EMV+ 731 ventilator and ZOLL Propaq MD cardiac monitor) was subjected to low (2.5 g), moderate (4.5 g), and variable acceleration (1.5–4.5 g) for 3-minute periods at the KBR Brooks Centrifuge. AE equipment was tested for functionality in 3 different orientations (gX, gY, and gZ). Predetermined variations were made in equipment input settings to ensure each equipment item would function across mission-relevant conditions (differing ventilator tidal volumes, differing cardiac monitor arterial pressure inputs, etc.). AE was evaluated for accuracy compared to controlled inputs, alarm conditions, and equipment failure. Results The EMV+ 731 ventilator and Propaq MD cardiac monitor had no equipment failures during testing. The ventilator had clinically negligible variations in tidal volume, peak pressure, and fraction of inspired oxygen during acceleration. At the highest tidal volume tested (480 mL), the ventilator had elevated peak pressure results. However, we believe this was due to limitations in test-lung resistance and was not related to a ventilator fault. Mild effects of sensor orientation were recorded in the Propaq MD blood pressure results; for example, gX and gY differed by 5.9 ± 1.21 mmHg at 75 mmHg input (P < .01) and 6.45 ± 1.229 mmHg with 150 mmHg input (P < .001). Conclusions The EMV+ 731 ventilator and Propaq MD cardiac monitor had reliable clinical performance despite sustained acceleration. This knowledge will facilitate immediate follow-on experimentation with advanced models of combat injury during simulated medical evacuation in sustained acceleration environments.

Toward Damage-Less Robotic Fragile Fruit Grasping: A Closed-Loop Force Control Method for Pneumatic-Driven Soft Gripper.

Fragile fruit uploading and packaging are labor-intensive and time-consuming steps in postharvest industry. With the aging of the global population, it is supposed to develop robotic grasping systems to replace manual labor. However, damage-less grasping of fragile fruit is the key problem in robotization. Inappropriate grasping force will result in damage, early-stage bruise, or slip. Benefits from the advantages of softness and compliance of a pneumatic-driven soft gripper have been widely adopted for agricultural product and food manipulation. Nevertheless, pneumatic gripper is a complex, multivariable, nonlinear, and long time-delay control system, which is difficult to achieve robust closed-loop grasping force control. In this study, we aim to solve this problem and developed a robotic grasping force control system with pneumatic gripper and matrix force sensor. The force distribution condition was explored to tackle the problem in changing of the main contact point. A double closed-loop control method was proposed based on Kalman filter (KF) and proportion integration differentiation controller with dead band. The external and internal control loops were force controller and air pressure of the pump controller, respectively. The double closed-loop controller with dead band achieved robust grasping force control through air pressure. The experimental results validated the effectiveness of the KF method for denoising and the matrix force visualization method for exploring grasping mechanism. Ablation studies were carried out to demonstrate the effectiveness of the multiple grasping force sensing units in matrix form and the dead band in the controller. The maximum steady-state error was 0.07 N. In addition, the generalization performance and the antidisturbance ability of the grasping force control system was also validated. In summary, the problem in closed-loop control of the grasping force for pneumatic gripper has been solved in our study, and the method in this research is potential to be deployed in fruit postharvest industry.

Development of a low-cost, 3-D printed, aspirated air-temperature measurement radiation shield

Abstract Accurate measurement of ambient air temperature is critical to numerous applications. This task is complicated by solar radiation which can heat the air-temperature sensor body, causing it to record temperatures in excess of the true air temperature. The standard way to protect against this interference is to house the sensors in passive radiation shields which block the majority of solar radiation. However, solar radiation still heats the shield body which can then heat the sensor, causing measurement errors under low-wind conditions. An alternative method is to aspirate the sensor using a fan to force air movement over the sensor body. Aspirated temperature sensing units are commercially available, but they can be expensive and consume a significant amount of power. Here, we present the design and initial rigorous testing of a low-cost, low-power aspirated temperature sensing unit designed to integrate with any low-cost distributed sensor platform. The design uses a freely available, custom designed 3-D printed housing that enables rapid assembly. The new, open source unit is shown to perform as well as passive shields and commercial aspirated shields of significantly higher cost. This success shows the potential of leveraging 3-D printing technologies for other housing units. Further testing is needed to better quantify long-term robustness of the shield.

Burden and Risk Factors of Cervical Spine Conditions in Military Aircrew From 1997 to 2015: A Retrospective Cohort Study.

Military aviators may have increased risk of cervical spine injuries because of exposure to supraphysiologic forces and vibration during dynamic flight. Aviator medical attrition impairs mission readiness, decreases operational capabilities, increases overall DoDcosts, and decreases retention of seasoned aviators. This study evaluated incidence and risk factors for cervical spine conditions in U.S. military aviators from 1997 to 2015. The Defense Medical Epidemiological Database was queried for aviators with a diagnosis of cervical spine conditions. Pertinent ICD-9 codes for cervical spine pathology were ascertained from U.S. Army, Air Force, and Naval Air Forces aeromedical references. Negative binomial regressions assessed sex, age, service, aircraft, and year on incidence of conditions. Rates were compared to non-aviator controls. The study was approved by the Institutional Review Board at the Naval Health Research Center (NHRC.2020.0205-NHSR). Incidence rates were 9.78 to 12.57/1,000 person-years for neck pain, 2.04 to 3.89/1,000 person-years for degenerative conditions without neurological involvement, and 0.94 to 1.36/1,000 person-years for degenerative conditions with neurological involvement. Aviation occupation (relative risk [RR] 1.41-2.05), female sex (RR 3.32-7.89), age over 40 (RR 2.39-4.62), and service in the Army or Marine Corps (RR 1.62-2.14) were risk factors. Military aviators had a statistically significant increase in risk of neck pain and medically disqualifying degenerative cervical spine conditions compared to non-aviator controls. Rates of neck pain increased in all aviators over the study epoch. Possible explanations could be related to the operational demands and the increased use of forward helmet-mounted display systems during the study period, a supposition that requires further investigation. There was no significant difference in rates of neck pain or degenerative cervical conditions between aircraft platforms (fighter/bomber, other fixed wing, and rotary wing). Female sex, age over 40 years, and Army/Marine Corps service were the greatest risk factors for neck pain and degenerative cervical spine conditions. Targeted prevention programs and expanded treatment modalities are necessary to reduce aviator attrition and Department of Defense cost burden.

All-climate battery thermal management system integrating units-assembled phase change material module with forced air convection

Phase change material (PCM) is widely adopted to construct integrated battery thermal management systems (BTMSs) for all climates. However, integrated BTMSs in cylindrical battery modules remain arduous challenges due to the compact/massive cuboid-shaped PCM module and the curved surface of the cells. Herein, we propose a novel all-climate BTMS integrating units-assembled composite PCM (CPCM) module with force air convection. The CPCM module assembled by sleeve-like CPCM units provides developed airflow channels and enlarged heat transfer surface from 1.17 × 10−3 to 3.63 × 10−3 m2 for enhancing convective heat transfer. Consequently, compared to conventional cuboid-shaped module, the thermal resistance of the units-assembled module is remarkably reduced by 52.0% and 60.1%, and the heat flux is enhanced by 7 times under both cooling and preheating modes. In cooling tests, this BTMS demonstrates superior performance by controlling the temperature and temperature difference below 40.30 and 2.80 °C at 3-C discharge, respectively. In preheating tests, it effectively preheats the battery module from 0 to 10 °C in 302 s with a low temperature difference of 3.82 °C. Furthermore, this units-assembled CPCM module saves 53.8 wt% of the CPCM dosage, and thus the energy density of the battery module is increased from 75.6 to 94.4 Wh·kg−1.

A brainstem circuit for phonation and volume control in mice

Mammalian vocalizations are critical for communication and are produced through the process of phonation, in which expiratory muscles force air through the tensed vocal folds of the larynx, which vibrate to produce sound. Despite the importance of phonation, the motor circuits in the brain that control it remain poorly understood. In this study, we identified a subpopulation of ~160 neuropeptide precursor Nts (neurotensin)-expressing neurons in the mouse brainstem nucleus retroambiguus (RAm) that are robustly activated during both neonatal isolation cries and adult social vocalizations. The activity of these neurons is necessary and sufficient for vocalization and bidirectionally controls sound volume. RAm Nts neurons project to all brainstem and spinal cord motor centers involved in phonation and activate laryngeal and expiratory muscles essential for phonation and volume control. Thus, RAm Nts neurons form the core of a brain circuit for making sound and controlling its volume, which are two foundations of vocal communication.

Sub-daily rainfall patterns in the mountainous regions of the Island of Tahiti: Insights from a one-year rain gauge network expansion

Study regionThe Island of Tahiti in French Polynesia (17.5°S,149.5°W), with a focus on the mountainous regions of the island interior. Study focusThe high topography of Tahiti creates an obstacle for wet air masses traveling along the surface of the South Tropical Pacific Ocean, which forces air flow uplift and triggers orographic rainfall. Although the main physical processes behind orographic rain enhancement on tropical islands were identified, the ways they shape Tahitian rain fields are still not fully understood, particularly due to a lack of observations. To address the limitations posed by this shortage of rain data, this study describes the temporary expansion of the rain gauge network of Tahiti towards the mountainous island interior, and uses the resultant dataset to investigate the spatial and temporal patterns of orographic rainfall at sub-daily resolution. New hydrological insights for the regionThe analysis of the rain gauge observations on daily and shorter time-scales leads to the identification of three main types of rainfall patterns: (1) a Dry Season Trade Winds type linked to a persistent Trade Winds Inversion (TWI) and characterized by moderate orographic rainfall in windward slopes, dry conditions in most leeward areas, and localized mid-afternoon showers in the mountains downwind of the main summit of the island; (2) a Transition Season Trade Winds type linked to atmospheric disturbances weakening the TWI, and characterized by intense orographic rainfall in windward slopes and mountains, and frequent showers in leeward areas by overshoot of the main crest; and (3) a SPCZ-related type occurring when the South Pacific Convergence Zone (SPCZ) crosses Tahiti during the wet season, and characterized by intense and widespread rainfall throughout the island with clear diurnal cycle and peak intensities recorded in the mid-afternoon.

Numerical simulation of the horizontal rotating cylinder and the air entrainment near the free surface

The flow around a cylinder near a free surface contains many physical phenomena and mechanisms, especially when the cylinder is moving. In this paper, the two-dimensional flow of a rotating cylinder near the free surface is simulated. The dynamic behavior of the rotating cylinder and the flow characteristics such as force coefficient, vortex structure, and air entrainment under different depth ratios, Fr numbers, and rotation ratios are discussed. In such problems, the rotational motion is rarely mentioned. The two-phase model is the sharp volume of the fluid method based on the two-dimensional incompressible Navier–Stokes equation. Combined with the spatially adaptive four-octree grid, the gas–liquid interface is reconstructed with the high-density ratio (ρwater/ρair = 816). The results show that, at α ≤ 2.0, the combined effect of the free surface and the rotation causes the wake vortex to produce a positive upper and negative lower distribution, which is contrary to the single condition. For the rotating cylinder, the existence of a free surface leads to the stable vortex layer at a low rotation ratio (α = 1.0), which only occurs at the high rotation ratio (2 < α < 4.2) without free surface. For the force coefficients, the simultaneous existence of the free surface and the rotation obviously changes the value and periodicity of the coefficients, which is different from the single condition. As for the air entrainment, it can be divided into two categories within the selected parameters: vortex entrainment caused by the parallel free surface and wake jet entrainment. In the latter model, the entailed bubbles have a wider distribution in space due to the influence of shedding vortices.

Mobility Aircrew Fatigue Perceptions and Mitigation Strategies

Abstract: Mobility aircrew operate in unique, high-tempo environments resulting in susceptibility to fatigue. In the current study we examined fatigue perceptions and mitigation strategies before and during mission execution with questionnaires from 44 volunteers from a US Air Force air mobility squadron. Results suggest that fatigue is a serious safety-of-flight concern for the community; however, crews generally did not reference the available fatigue risk management (FRM) tool for missions. Aircrew member characteristics were associated with differences in fatigue-related perceptions and mitigation strategies. Crews used various personal fatigue mitigation strategies and had habitual stimulant and depressant consumption during missions based on daily routines. We discuss implications of these findings for FRM tools.

Modification of The Oil Cooler to Avoid Oil Leaking in Generator Transformer PLTU Labuan “Moderator”

The Main Generator Transformer for PLTU Labuan is a transformer with a power capacity of 350 MVA and a cooling system of 6 pcs OFAF (Oil Force Air Force) type. During operation, a disturbance to the Main Generator Transformer (GT) was caused by an oil cooler leak. This is caused by the corrosive expand tube caused by the constituent material consisting of 2 different types of materials. The oil leak caused environmental pollution, decreased oil level, and increased winding temperature and oil temperature on GT. During the decade of operation of the PLTU Labuan, GT oil cooler leaks almost always occur every year, both in unit 1 and unit 2. To anticipate this, we made modifications to the end tube design by changing the type of material on the expanded tube from initially using iron to aluminum such as tube material outside the expanded position. The next design change is to increase the length of the end tube which is equipped with the knock and glue with an expansion strength above normal operating temperature which makes the end tube more reliable by increasing the surface area attached to the body oil cooler. In addition to making changes to the design, this modification reuses used oil coolers that have good tube quality so that they can be reused with more reliable quality. By making these modifications, it can increase the readiness of generating unit production (EAF) by 3.33% in one MO event due to the replacement of the oil cooler generator transformer and lower maintenance costs for the required transformer oil cooler. The modified Oil Cooler was installed during the Maintenance Outage in Unit 1 and Overhaul unit 2 in 2021 and is still operating well for 20 months of operation.

Research on roughness prediction model of robotic sanding carbon fiber reinforced plastics

By taking a pneumatic eccentric grinder and round sandpapers as research objects, the modeling method is proposed to accurately predict the surface roughness of robotic sanding carbon fiber reinforced plastic parts. A four-factor, the four-level orthogonal experiment was conducted which took four process parameters into account: pressing force, feeding speed, grit size, and supply air pressure. The multiple linear regression analysis method was then applied to create a roughness prediction model. Furthermore, accuracy validation results show that the model’s prediction error is within ±9%.

0734 Gender Differences in US Military Personnel with Insomnia, Obstructive Sleep Apnea & Comorbid Insomnia and Obstructive Sleep Apnea

Abstract Introduction Women constitute approximately 17% of the military. Yet, relatively little is known regarding sleep disorders and comorbid diagnoses effecting this gender. The aim of this study was to determine if there were gender-related differences in symptoms of sleep disorders and sleep-related impairment, comorbid sleep, behavioral medicine, and traumatic brain injury (TBI) diagnoses and polysomnographic (PSG) variables in military personnel with insomnia, OSA, and comorbid insomnia and OSA (COMISA). Methods Participants were 372 military personnel (46.2% females, 53.8% males) with an average age of 37.7±7.46 years and median BMI of 28.4 (5.50) kg/m2. Based on clinical evaluation and video-PSG, participants were diagnosed with insomnia (n = 118, 71.2% female), OSA (n = 118, 28.8% female) and COMISA (n = 136, 39.7% female). Insomnia severity, excessive daytime sleepiness, sleep quality, nightmare disorder, sleep impairment, fatigue, posttraumatic stress disorder (PTSD), anxiety, depression symptoms, and traumatic brain injury (TBI) were evaluated with validated questionnaires. Descriptive statistics, parametric and non-parametric pairwise comparisons and effect-size analyses were used to assess differences between sexes in terms of variables of interest. Results Female service members had significantly greater symptoms of nightmare disorder, PTSD, anxiety, and depression than their male counterparts. There were no significant differences between males and females with insomnia or OSA in sleep-related symptoms, impairment, or PSG based apnea-hypopnea index (AHI). Male service members with COMISA had a significantly greater AHI; females with COMISA had significantly greater symptoms of nightmare disorder, PTSD and anxiety. Conclusion In the largest study to date to clinically evaluate sleep disorders in military personnel, COMISA was the most frequent diagnosis. Surprisingly, there were minimal differences in self-reported symptoms of sleep disorders and PSG characteristics. However, male servicemembers with COMISA have more severe sleep disordered breathing while female servicemembers with COMISA have greater mental health morbidity. Military service may result in distinct sleep disorder phenotype(s). Support (if any) This work was supported by the Defense Health Agency, Defense Medical Research and Development Program, Clinical Research Intramural Initiative for Military Women’s Health (DM170708; Mysliwiec) and the US Air Force (USAF) Air Force Materiel Command (AFMC), Wright Patterson Air Force Base, Ohio (FA8650-18-2-6953; Peterson).

Performance Estimation and System Modeling for Refractive Index Structure Constant Cn2

Random turbulence fluctuations cause continuous fluctuations in the refractive index, which will eliminate the coherence of light waves. Research into atmospheric turbulence is in fact an investigation of the atmospheric refractive index. The constant of atmospheric structure represents a significant parameter that is indicative of the strength of the atmospheric turbulence. In the present study, the performance of some standard models, such as Hufnagel-Valley 5/7, Sub-mission Laser Communication, Critical Laser Enhancing Atmospheric Research, and the Air Force Geophysics Laboratory and Air Force Maui Optical Station, for estimating the, was evaluated with a focus on location assessment. The bias and RMSE were found to be significantly less than 1x10-14 m^-2/3 for Holloman and Hefei cities, and σ is basically less than 0.25x10-14 m^-2/3 for Holloman and Hefei cities. During day and night transitions, Rxy, is well for Holloman, Louisiana, and Hefei cities. Using standard models, we discovered a satisfactory match between the measured (observed) and estimated values for tropical locations.

The 2022 monkeypox outbreak: A UK military perspective.

With the emergence of SARS-CoV-2 and now monkeypox, the UK Defence Medical Services have been required to provide rapid advice in the management of patients with airborne high consequence infectious diseases (A-HCID). The Defence Public Health Network (DPHN) cadre, consisting of closely aligned uniformed and civilian public health specialists have worked at pace to provide evidence-based recommendations on the clinical management, public health response and policy for monkeypox, with military medicine and pathology clinicians (primarily infectious disease physicians and medical microbiologists). Military environments can be complicated and nuanced requiring specialist input and advice to non-specialists as well as unit commanders both in the UK and overseas. DPHN and military infection clinicians have close links with the UK National Health Service (NHS) and the UK Health Security Agency (UKHSA), allowing for a dynamic two-way relationship that encompasses patient management, public health response, research and development of both UK military and national guidelines. This is further demonstrated with the Royal Air Force (RAF) Air Transport Isolator (ATI) capability, provided by Defence to support the UK Government and UKHSA. Military infectious disease clinicians are also embedded within NHS A-HCID units. In this manuscript we provide examples of the close interdisciplinary working of the DPHN and Defence clinicians in managing military monkeypox patients, co-ordinating the public health response, advising the Command and developing monkeypox policy for Defence through cross-government partnership. We also highlight the co-operation between civilian and military medical authorities in managing the current outbreak.

METHOD OF EVALUATION OF MILITARY HELICOPTER PILOT SELECTION CRITERIA: A NOVEL GREY SWARA APPROACH

Helicopter is a very important defence and attack tool for a country’s armed forces (army) (air force). With the rapid progress of technology, the designs of helicopters, the hardware and software elements in the helicopter have also been renewed and developed in parallel with advanced technology. Therefore, it is expected that the pilots who will use helicopters, which are an important flight tool of armed forces, will also have the qualifications to provide the necessary knowledge, skills, and criteria. The aim of the study is to determine the military helicopter pilot selection criteria and to find the importance levels of these criteria. For this purpose, three main criteria as “Health”, “Psychomotor” and “Education and Training” and thirteen sub-criteria were determined. The weights of the determined criteria were found by the Grey SWARA method, which is a current multi criteria decision making tool. According to the results of the analysis, it is found that the most important sub-criteria was “Practical Training”, while the lowest important criteria was the “Height and weight limits” criterion. With this study, the weights of the military helicopter pilot selection criteria were found for the first time with the Grey SWARA method.

Proposed Thalmann algorithm air diving decompression table for the Swedish Armed Forces

The Swedish Armed Forces (SwAF) air dive tables are under revision. Currently, the air dive table from the U.S. Navy (USN) Diving Manual (DM) Rev. 6 is used with an msw-to-fsw conversion. Since 2017, the USN has been diving according to USN DM rev. 7, which incorporates updated air dive tables derived from the Thalmann Exponential Linear Decompression Algorithm (EL-DCM) with VVAL79 parameters. The SwAF decided to replicate and analyze the USN table development methodology before revising their current tables. The ambition was to potentially find a table that correlates with the desired risk of decompression sickness. New compartmental parameters for the EL-DCM algorithm, called SWEN21B, were developed by applying maximum likelihood methods on 2,953 scientifically controlled direct ascent air dives with known outcomes of decompression sickness (DCS). The targeted probability of DCS for direct ascent air dives was ≤1% overall and ≤1‰ for neurological DCS (CNS-DCS). One hundred fifty-four wet validation dives were performed with air between 18 to 57 msw. Both direct ascent and decompression stop dives were conducted, resulting in incidences of two joint pain DCS (18 msw/59 minutes), one leg numbness CNS-DCS (51 msw/10 minutes with deco-stop), and nine marginal DCS cases, such as rashes and itching. A total of three DCS incidences, including one CNS-DCS, yield a predicted risk level (95% confidence interval) of 0.4-5.6% for DCS and 0.0-3.6% for CNS-DCS. Two out of three divers with DCS had patent foramen ovale. The SWEN21 table is recommended for the SwAF for air diving as it, after results from validation dives, suggests being within the desired risk levels for DCS and CNS-DCS.

Hans Jakob Piloty [Pioneers in CAS

Hans Jakob Piloty came from an upper-class Munich family of artists and scholars. In 1913, he began studying electrical engineering at the Technical University of Munich. After volunteering in the First World War, he obtained his diploma in 1921 and received his doctorate in 1923 under Leo Kadrnozka (1872–1922). From 1925 he was chief engineer at AEG Berlin. In the power plants department, he worked on questions relating to energy transmission. In 1931 he was appointed to the Chair for Electrical Measurement Technology at TUM. In his institute, during the Nazi regime, “war-important” orders in the field of telecommunications, high-frequency technology and electroacoustics were carried out for all three armed forces (army, air force and navy).

Proposed Thalmann Algorithm Air Diving Decompression Table for the Swedish Armed Forces Based on Logistic Probabilistic Modeling of No-Stop Air Diving Data

The Swedish Armed Forces (SwAF) air dive tables are under revision. Currently, the air dive table from US Navy (USN) Diving manual (DM) Rev.6 is used with a msw to fsw conversion. Since 2017, USN has been diving according to USN DM rev. 7, which incorporates updated air dive tables derived from the exponential linear decompression algorithm (EL-DCM) Thalmann with VVAL79 parameters. The SwAF decided to replicate and analyze the USN table development methodology before revising their current tables. The ambition was to potentially find a table that correlates with the desired risk of decompression sickness. New compartmental parameters for the EL-DCM algorithm, called SWEN21B, were developed by applying maximum likelihood methods on 2953 scientifically controlled direct ascent air dives with known outcomes of decompression sickness (DCS). The targeted probability of DCS for direct ascent air dives was ≤1% overall and ≤1‰ for neurological DCS (CNS-DCS). 154 wet validation dives were performed with air between 18-57 msw. Both direct ascent and decompression stop dives were conducted, resulting in two joint pain DCS (18msw/59min), one leg numbness CNS-DCS (51msw/10min with deco-stop), and nine marginal DCS, such as rashes and itching. A total of three DCS, including one CNS-DCS, yield a predicted risk level (95% confidence interval) of 0.4-5.6% for DCS and 0.0-3.6% for CNS-DCS. Two out of three divers with DCS had patent foramen ovale, PFO. The SWEN21 table is recommended for the SwAF for air diving as it, after results from validation dives, suggests being within the desired risk levels for DCS and CNS-DCS.

Differential Equations of Motion of the Particle

This paper deals with linearized and normalized differential equations of relative motion of the system under the influence of magnetic force air resistance and oblateness of the earth in Nechvill's co-ordinate system. We have linearized the problem keeping in view that the length of the string connecting the two satellites is infinitesimally small in comparison to the distance of centre of mass of the system from the centre of attracting force and introduction of rotating frame of reference eliminates the product terms as usual. We have obtained a system of six orders non-autonomous, non-linear equations of motion describe the motion of one of two satellites and the motion of satellite relative to the first may easily be obtained by m1ρ1 + m2ρ2 = 0