Frequency Of Maneuvers Research Articles

A Method to Determine BeiDou GEO/IGSO Orbital Maneuver Time Periods.

Because there are different types of BeiDou constellations with participating geostationary orbit (GEO) and inclined geosynchronous orbit (IGSO) satellites, the maneuvering frequency of BeiDou satellites is higher than that of other navigation systems. The satellite orbital maneuvers lead to orbital parameter failure for several hours from broadcast ephemeris. Due to the missing initial orbit, the maneuvering thrust, and the period of orbital maneuvering, the orbit products of maneuvering satellites cannot be provided by the International Global Navigation Satellite System (GNSS) Service (IGS) and International GNSS Monitoring and Assessment System (iGMAS). In addition, the period of unhealthy status and the orbital parameters of maneuvering satellites in broadcast ephemeris are unreliable, making the detection of orbital maneuver periods more difficult. Here, we develop a method to detect orbital maneuver periods involving two key steps. The first step is orbit prediction of maneuvering satellites based on precise orbit products. The second step is time period detection of orbit maneuvering. The start time detection factor is calculated by backward prediction orbit and pseudo-range observations, and the end time detection factor is calculated by forward prediction orbit and pseudo-range observations. Data of stations from the Multi-GNSS Experiment (MGEX) and iGMAS were analyzed. The results show that the period of orbit maneuvering could be detected accurately for BeiDou GEO and IGSO satellites. In addition, the orbital maneuver period of other GNSS medium Earth orbit (MEO) satellites could also be determined by this method. The results of period detection for orbit maneuvering provide important reference information for precision orbit and clock offset determination during satellite maneuvers.

Outcomes of use of electromagnetic guidance with responsive insertion technology (RIT) during colonoscopy: a prospective randomized controlled trial.

Background and study aims Colonoscopy can be technically challenging and cause discomfort in patients. The integrated Scope Guide assist is built in to show that with its use outcomes are improved during colonoscopy. We aimed to test the usefulness of the Magnetic Scope Guide Assist (ScopeGuide ) with respect to cecal intubation time, and other procedural quality outcomes. Patients and methods We conducted a prospective study of outpatients undergoing elective colonoscopy at the endoscopic units of the University of Alabama at Birmingham (UAB) from March 2016 to July 2016. Patients were randomly assigned in a 1:1 block design to groups that either had standard colonoscopy or Scope-guided colonoscopy. The primary outcome measure was cecal intubation time (CIT). Secondary outcome measures included use of manual pressure, position changes for cecal intubation and sedation requirements. Results Three hundred patients were randomized to either group; standard (n = 150) vs. Scope-guided (n = 150). The mean CIT was not statistically different for the standard and the Scope-guided groups (4.6 vs. 4.3 minutes; P = 0.46). There were also no statistical differences in frequency of manual pressure applied (16.7 % for Scope-guided vs. 19.1 % for standard; P = 0.65) or position changes (11.4 % for scope guided vs. 8.8 % standard; P = 0.56). Sedation requirements showed lesser use of midazolam (3.9 mg vs. 4.7 mg, P = 0.003) in the Scope-guide group, while there was no significant difference in use of fentanyl (fentanyl – 62.1 mg vs. 68.9 mg, P = 0.09 similar between groups, for Scope-guided vs. standard groups, respectively). Adverse events were similar in both groups. Conclusions In patients undergoing routine elective colonoscopy, use of ScopeGuide by experienced colonoscopists did not improve CIT or affect the frequency of ancillary maneuvers. The benefit of this device during training of endoscopists could be considered for further studies.

Trajectory Tracking Near Small Bodies Using Only Attitude Control

Gravitational orbit–attitude coupling shows a noticeable influence on the motion of a rigid spacecraft in close proximity to small solar system bodies. The gravity gradient moment changes the attitude of the spacecraft, which in turn alters the total gravity force on the spacecraft and has an impact on the orbital motion. In this paper, the polyhedron model of small bodies is adopted and a distributed point-mass model of the spacecraft is developed to reflect this coupling phenomenon more accurately. In particular, taking advantage of the gravitational orbit–attitude coupling, a trajectory tracking scheme for a rigid body using only attitude control is proposed. By changing the attitude of the spacecraft, the gravitational orbit–attitude coupling generates a control force to make the spacecraft track the reference trajectory. This reference trajectory is generated based on a point-mass model. Simulation results in landing and orbiting around asteroid Bennu show the feasibility of this tracking approach. A significant improvement is seen for the coupling-based controlled trajectory over natural motions. The tracking scheme reduces the frequency of orbit control maneuvers and provides a redundant control in the event of thruster failures. This approach can be used as a reference for future small-body missions.

Network-level comparison of various Forward Collision Warning algorithms

Rear-end collisions represent a quarter to one-third of the total number of collisions occurring on North American roads. Consequently, Forward Collision Warning (FCW) algorithms have been developed to mitigate this type of critical collision by warning drivers about an impending rear-end event. The algorithms are typically tested to ensure their effectiveness in reducing specific events, such as rear-end conflicts and/or collisions, or by assessing the change in the frequency and severity of braking maneuvers. Such assessments are usually microscopic in nature and deal with isolated (independent) situations. This paper aims at assessing six FCW algorithms at a network level with varying market penetration rates using a calibrated micro-simulation model. The algorithms were assessed in terms of their safety (rear-end conflicts frequency), mobility (travel times), and environmental impacts (emissions and fuel consumption). Based on the results of this study, most of the FCW algorithms did not have a significant effect on mobility nor environmental impacts at various market penetration rates. On the contrary, all the algorithms showed significant safety improvements, in terms of reducing rear-end conflicts, as the market penetration rates increased. The only exception was a single algorithm that tends to be more conservative in terms of braking distance. The results showed that situational improvements (on a driver level) caused by using FCW systems will generally translate into systematic improvements (on a network level). This is important due to the anticipated gradual increase in intelligent vehicles, which are expected to be equipped with FCW systems, on our roads soon.

Effects of positive end-expiratory pressure and recruitment maneuvers in a ventilator-induced injury mouse model.

BackgroundPositive-pressure mechanical ventilation is an essential therapeutic intervention, yet it causes the clinical syndrome known as ventilator-induced lung injury. Various lung protective mechanical ventilation strategies have attempted to reduce or prevent ventilator-induced lung injury but few modalities have proven effective. A model that isolates the contribution of mechanical ventilation on the development of acute lung injury is needed to better understand biologic mechanisms that lead to ventilator-induced lung injury.ObjectivesTo evaluate the effects of positive end-expiratory pressure and recruitment maneuvers in reducing lung injury in a ventilator-induced lung injury murine model in short- and longer-term ventilation.Methods5–12 week-old female BALB/c mice (n = 85) were anesthetized, placed on mechanical ventilation for either 2 hrs or 4 hrs with either low tidal volume (8 ml/kg) or high tidal volume (15 ml/kg) with or without positive end-expiratory pressure and recruitment maneuvers.ResultsAlteration of the alveolar-capillary barrier was noted at 2 hrs of high tidal volume ventilation. Standardized histology scores, influx of bronchoalveolar lavage albumin, proinflammatory cytokines, and absolute neutrophils were significantly higher in the high-tidal volume ventilation group at 4 hours of ventilation. Application of positive end-expiratory pressure resulted in significantly decreased standardized histology scores and bronchoalveolar absolute neutrophil counts at low- and high-tidal volume ventilation, respectively. Recruitment maneuvers were essential to maintain pulmonary compliance at both 2 and 4 hrs of ventilation.ConclusionsSigns of ventilator-induced lung injury are evident soon after high tidal volume ventilation (as early as 2 hours) and lung injury worsens with longer-term ventilation (4 hrs). Application of positive end-expiratory pressure and recruitment maneuvers are protective against worsening VILI across all time points. Dynamic compliance can be used guide the frequency of recruitment maneuvers to help ameloriate ventilator-induced lung injury.

Adaptive maneuvering frequency method of current statistical model

Current statistical model U+0028 CSM U+0029 has a good performance in maneuvering target tracking. However, the fixed maneuvering frequency will deteriorate the tracking results, such as a serious dynamic delay, a slowly converging speedy and a limited precision when using Kalman filter U+0028 KF U+0029 algorithm. In this study, a new current statistical model and a new Kalman filter are proposed to improve the performance of maneuvering target tracking. The new model which employs innovation dominated subjection function to adaptively adjust maneuvering frequency has a better performance in step maneuvering target tracking, while a fluctuant phenomenon appears. As far as this problem is concerned, a new adaptive fading Kalman filter is proposed as well. In the new Kalman filter, the prediction values are amended in time by setting judgment and amendment rules, so that tracking precision and fluctuant phenomenon of the new current statistical model are improved. The results of simulation indicate the effectiveness of the new algorithm and the practical guiding significance.

Range tracking method based on adaptive “current” statistical model with velocity prediction

This study considers the problem of range tracking of a maneuvering target by an airborne digital array radar system. In the classic “current” statistical (CS) model, the maneuvering frequency α is not adaptive, and an acceleration limit has to be set. First, a new range tracking method called “adaptive CS model with velocity prediction” (ACSMVP) is proposed. This method utilizes the velocity prediction algorithm of cross product automatic frequency control with loop filter to measure the radial acceleration between the radar and the target. With the acceleration been obtained, the maneuvering frequency is derived, which is calculated in every tracking period. Second, an improved algorithm called “Sage–Husa-based ACSMVP” (SH-ACSMVP) is also proposed. In this algorithm, an online measuring noise covariance matrix is achieved by a simplified Sage–Husa estimator. Third, a Cramér-Rao lower bound of pulse-Doppler pulse train signal for range estimation is derived to assess the range tracking performance of the proposed algorithms. Simulations highlight the superior performance of our proposed algorithms over existing techniques.

Use of an Abdominal Compression Device in Colonoscopy: A Randomized, Sham-Controlled Trial.

Looping is a common problem during colonoscopy that prolongs procedure time. We aimed to determine the efficacy and safety of ColoWrap, an external abdominal compression device, with respect to insertion time and other procedural outcomes. We performed a prospective study of outpatients undergoing elective colonoscopy (40-80 years old; mean age, 60.5 years) at endoscopy facilities in the University of North Carolina Hospitals from April 2013 through March 2014. Subjects were randomly assigned to groups that received either ColoWrap (n= 175) or a sham device (control, n= 175) during colonoscopy. Colonoscopists and staff were blinded to the application. The primary outcome was cecal intubation time (CIT). Secondary outcomes included use of manual pressure and position change. The mean CIT was similar for the control and ColoWrap groups (6.69 vs 6.67 minutes; P= .98). There were no statistical differences in the frequency of manual pressure (45% for controls vs 37% for ColoWrap group, P= .13) or position changes (4% for controls vs 2% for ColoWrap group, P= .36). Among patients with body mass index between 30 and 40 kg/m(2) (n= 78), CIT was significantly lower for patients in the ColoWrap group (4.69 minutes) than controls (6.10 minutes) (P= .03). Adverse events were similar between groups. In patients undergoing elective colonoscopy, application of an external abdominal compression device did not improve CIT or affect the frequency of ancillary maneuvers. A possible benefit was observed in patients with body mass index between 30 and 40 kg/m(2), but further studies are needed. ClinicalTrials.gov number: NCT02025504.

Identification of freeway crash-prone traffic conditions for traffic flow at different levels of service

The primary objective of this study was to evaluate the risks of crashes associated with the freeway traffic flow operating at various levels of service (LOS) and to identify crash-prone traffic conditions for each LOS. The results showed that the traffic flow operating at LOS E had the highest crash potential, followed by LOS F and D. The traffic flow operating at LOS B and A had the lowest crash potential. For LOS A and B, the vehicle platoon and abrupt change in vehicle speeds were major contributing factors to crash occurrences. For LOS C, crash risks were correlated with lane-change maneuvers, speed variation, and small headways in traffic. For LOS D, crash risks increased with an increase in the temporal change in traffic flow variables and the frequency of lane-change maneuvers. For LOS E, crash risks were mainly affected by high traffic volumes and oscillating traffic conditions. For LOS F, crash risks increased with an increase in the standard deviation of flow rate and the frequency of lane-change maneuvers. The findings suggested that the mechanism of crashes were quite different across various LOS. A Bayesian random-parameters logistic regression model was developed to identify crash-prone traffic conditions for various LOS. The proposed model significantly improved the prediction performance as compared to the conventional logistic regression model.

Sense and Avoid

This study explored the ability of operators to provide separation between three unmanned aircraft using basic cockpit traffic displays. Four groups of three general aviation, instrument-rated pilots flew cross-country flights controlling simulated twin-engine unmanned aircraft systems (UAS). They were required to maintain 2 nautical miles (nmi) horizontal and 500 ft vertical separation from all other aircraft. To examine the effect of two important safety factors, the flights were conducted with and without communication among the operators and with and without variable accuracy in the displayed traffic location due to degraded sensor quality. Twenty four different three-dimensional traffic conflict trajectories with three UASs, were repeated randomly for each of the four experimental conditions for each group. Of the 1152 aircraft encounters 12.8% were in violation of separation minimums. Eighteen of these were closer than 400 ft vertically or 1.6 nmi horizontally. The minimum separation of all aircraft pairs was 293 ft and 0.13 nmi. No difference in minimum separations was found due to the presence of communications, the variable accuracy of traffic position, or the participant group. The type and time of evasive maneuvers showed no effect when displayed horizontal position accuracy was variable. When operators were able to communicate and coordinate their maneuvers, the time to resolve the conflict was reduced. Participant groups varied significantly in: time of conflict resolution, frequency and type of maneuvers, control activity, reported amount of threat, confidence, satisfaction, and appraisal of the efficacy of their communications. The findings of this study serve as a benchmark for the development of sense and avoid procedures and minimum equipage standards for operating UASs in the airspace over the United States.

Offensive Agility Techniques Performed during International Netball Competition

Netball is a sport characterised by sharp changes-of-direction to break free from opponents. The ability of players to use changes-of-direction to evade opponents is, therefore, an important aspect of attacking play. The purpose of this study was to examine the performance and outcomes of offensive agility techniques utilised by netball players. Offensive agility techniques were assessed for the type of manoeuvre performed and performance outcome using video footage of three international matches. Mid and attacking playing positions performed a greater frequency of manoeuvres than defensive playing positions. The type of manoeuvre was found to have no influence on the performance outcome. The performance outcome is likely influenced by additional factors, such as location on the court, time constraints, or features of defensive opponents. Overall, the use of offensive agility manoeuvres was identified as an important aspect of attacking play in netball, particularly for the mid and attacking playing positions.

Hypersonic Vehicle Tracking Based on Improved Current Statistical Model

A new method of tracking the near space hypersonic vehicle is put forward. According to hypersonic vehicles’ characteristics, we improved current statistical model through online identification of the maneuvering frequency. A Monte Carlo simulation is used to analyze the performance of the method. The results show that the improved method exhibits very good tracking performance in comparison with the old method. DOI: http://dx.doi.org/10.11591/telkomnika.v11i11.2786 Full Text: PDF

Traffic safety impacts of irregular overtaking in left-turn lanes at road intersections outside built-up areas

Overtaking is a high risk maneuver for road users, still drivers often accept this risk, moreover they often commit irregular overtaking maneuvers. The paper gives some overview on traffic violations and irregular overtaking maneuvers. Left-turn lanes on major roads are usual elements of un-signalized at-grade junctions on two-lane roads outside urban areas. In several cases the left-turn lane, built for safety reasons, has the unintended negative effect, of becoming a dangerous spot. The paper analyses overtaking maneuvers at left-turn lanes on Hungarian roads. Site surveys were completed at typical sites outside built-up areas. Relationships between the frequency of irregular maneuvers, accident statistics, geometric parameters and traffic data are analyzed.

ABSOLUTE ADAPTIVE CS MODEL AND MODIFIED STRONG TRACKING UNSCENTED FILTER FOR HIGH MANEUVERING TARGET TRACKING

Absolute adaptive current statistical (AACS) model and modifled strong tracking unscented fllter (MSTUF) are proposed for maneuvering target tracking (MTT) under nonlinear measurement in this paper. The key point of the AACS model is to associate the instantaneous acceleration variance with some elements of state covariance matrix by constructing acceleration increment models of the acceleration limit and acceleration mean in the CS model, while the maneuvering frequency can adjust itself according to the change of the measurement residual. MSTUF is proposed for high maneuver tracking under nonlinear measurement by incorporating the modifled strong tracking fllter (STF) into the unscented fllter (UF). Since the state covariance, process noise covariance and maneuvering frequency can adjust themselves jointly according to the residual, the proposed algorithm, called the AACS-MSTUF, has a good performance on both maneuver and non-maneuver. Simulation results indicate that the overall performance of the proposed algorithm is better than the interacting multiple-model unscented fllter (IMM-UF), UF and original strong tracking unscented fllter (STUF) based on the CS model (CS- STUF) when considering tracking accuracy, stability, convergence and computational complexity.

Flies dynamically anti-track, rather than ballistically escape, aversive odor during flight

Tracking distant odor sources is crucial to foraging, courtship and reproductive success for many animals including fish, flies and birds. Upon encountering a chemical plume in flight, Drosophila melanogaster integrates the spatial intensity gradient and temporal fluctuations over the two antennae, while simultaneously reducing the amplitude and frequency of rapid steering maneuvers, stabilizing the flight vector. There are infinite escape vectors away from a noxious source, in contrast to a single best tracking vector towards an attractive source. Attractive and aversive odors are segregated into parallel neuronal pathways in flies; therefore, the behavioral algorithms for avoidance may be categorically different from tracking. Do flies plot random ballistic or otherwise variable escape vectors? Or do they instead make use of temporally dynamic mechanisms for continuously and directly avoiding noxious odors in a manner similar to tracking appetitive ones? We examine this question using a magnetic tether flight simulator that permits free yaw movements, such that flies can actively orient within spatially defined odor plumes. We show that in-flight aversive flight behavior shares all of the key features of attraction such that flies continuously 'anti-track' the noxious source.

아리랑위성 2호, 5호의 우주파편 충돌회피기동 주기 분석

본 논문에서는 현재 운용 중인 아리랑위성 2호와 발사예정인 아리랑위성 5호의 우주파편 충돌 회피기동 주기를 분석하였다. 이때, 각 위성들의 임무궤도 특성, 충돌 회피 여유시간, 허용 충돌확률, 위치 불확실성 등의 인자들의 변화에 따라 분석을 수행하였다. 또한, 결과의 타당성을 검증하기 위해 실제 1년 동안 생성된 NORAD TLE 카탈로그(catalog) 상의 우주 물체들과 아리랑위성 2호와의 충돌 회피기동 주기를 계산하였다. 분석 결과, 두 위성 모두 연중 약 1회 충돌 회피기동이 요구됨을 확인할 수 있었으며, 계산 인자들의 변화에 따른 결과 분석을 통해 추후 발사 예정인 저궤도 위성들의 충돌 회피기동 주기 예측 정밀도를 향상시키기 위한 방안들을 제시하였다. In this paper, a collision avoidance maneuver frequency for the KOMPSAT-2 and the KOMPSAT-5 is analyzed. For the statistical prediction of the avoidance maneuver frequency, mission orbits, responsive time, accepted collision probabilities, and positional uncertainties of primary and secondary objects are considered. In addition, the collision avoidance maneuver frequency of the KOMPSAT-2 is compared to the case that NORAD catalog during one year is used to calculate that of the KOMPSAT-2. As a result, the collision avoidance maneuver frequency is one per year on average and effective factors on the statistical prediction of the avoidance maneuver frequency are investigated. Efforts to improve its prediction accuracy are also discussed.

Two Alternating Motor Programs Drive Navigation in Drosophila Larva

When placed on a temperature gradient, a Drosophila larva navigates away from excessive cold or heat by regulating the size, frequency, and direction of reorientation maneuvers between successive periods of forward movement. Forward movement is driven by peristalsis waves that travel from tail to head. During each reorientation maneuver, the larva pauses and sweeps its head from side to side until it picks a new direction for forward movement. Here, we characterized the motor programs that underlie the initiation, execution, and completion of reorientation maneuvers by measuring body segment dynamics of freely moving larvae with fluorescent muscle fibers as they were exposed to temporal changes in temperature. We find that reorientation maneuvers are characterized by highly stereotyped spatiotemporal patterns of segment dynamics. Reorientation maneuvers are initiated with head sweeping movement driven by asymmetric contraction of a portion of anterior body segments. The larva attains a new direction for forward movement after head sweeping movement by using peristalsis waves that gradually push posterior body segments out of alignment with the tail (i.e., the previous direction of forward movement) into alignment with the head. Thus, reorientation maneuvers during thermotaxis are carried out by two alternating motor programs: (1) peristalsis for driving forward movement and (2) asymmetric contraction of anterior body segments for driving head sweeping movement.

Attending overtaking cars and motorcycles through the mirrors before changing lanes

Right of way violation crashes are the most common type of accidents that motorcyclists face. This study assessed right of way decisions in scenarios which require noticing whether there is traffic from behind that is about to overtake. A test was created which presents participants clips with a wide field of vision (from a driver's perspective in a moving vehicle), with mirror information inset that allows either cars or motorcycles that are about to overtake, to be attended. Novice and experienced car drivers, and dual drivers (with both car and motorcycle experience), watched these clips while their eye movements were monitored. The results indicated that in the rear-view and the right-side mirrors, and in the right hand lane, conflicting motorcycles garnered more attention than conflicting cars. This pattern however was particularly driven by the dual drivers group. Additionally, novice drivers and dual drivers made more use of the right side mirror than the experienced drivers. Dual drivers also made more use of the rear view mirror than experienced drivers. Finally, significant positive correlations that were found between percentages of safe manoeuvres and measures of visual search provide direct evidence demonstrating that the frequency of risky manoeuvres was indeed larger in those cases where less time was spent gazing at the mirrors, indicating that the additional attention devoted to process conflicting vehicles contributes to reduce risky manoeuvres. The general pattern of results also provides some indirect support that non-motorcyclists drivers are more likely to have Look But Fail To See errors with conflicting motorcycles than motorcyclist drivers.

Decreasing strain on the surgeon in gynecologic minimally invasive surgery by using semi-active robotics

Objective To assess the advantages of a surgeon-controlled robotic endoscope holder in gynecologic minimally invasive solo-surgery as compared with conventional assistance with a second surgeon. Methods One hundred gynecologic laparoscopies were consecutively allocated to surgery with either a robot as the surgical assistant or a conventional assistant surgeon. Total operation time, image stability, and frequency of corrective maneuvers of the camera, in addition to the surgeon's satisfaction regarding the ergonomics of the intervention, were recorded. All interventions were performed by the same surgeon. All laparoscopic surgery was classified as either easy or advanced surgery. Results The image stability score was significantly higher (10 vs 7; P < 0.001) and fewer corrective maneuvers of the robotic endoscope were necessary (1 vs 5; P < 0.001) with the robotic laparoscope holder; in addition, the surgeon recorded a significantly higher satisfaction score for the ergonomics of the semi-active robot (10 vs 7; P < 0.001). Conclusion The robot does not prolong total operation time and increases the surgeon's comfort by improving image stability and laparoscope handling. It could provide major benefit, especially in complex gynecologic laparoscopic surgery.

The Frequency of Surgical Maneuvers during Open Rhinoplasty

The improved exposure afforded by the external rhinoplasty approach has allowed for more precise surgical maneuvers and makes more consistent results possible. This study examines the frequency and array of surgical maneuvers during primary aesthetic rhinoplasty in a single surgeon's practice. A retrospective review of 100 consecutive primary external cosmetic rhinoplasty patients with a minimum follow-up of approximately 1 year was conducted. Surgical maneuvers were reviewed and tabulated. Special attention was devoted to the number of cartilage grafts and suturing techniques used. Operative times and incidence of revision surgery were investigated. The mean duration of surgery was 1 hour 50 minutes. The majority of rhinoplasties involved concomitant septal surgery for deviation and airway occlusion or cartilage harvesting. Osteotomies were performed on over 95 percent of patients. The dorsal hump was removed on 84 percent of the patients. The most common grafts used included alar rim grafts in 88 percent, subdomal grafts in 77 percent, and spreader grafts in 74 percent. Sutures used to contour the cartilage included transdomal sutures in 62 percent, followed by footplate approximation sutures in 32 percent. Seventy-seven patients had interdomal sutures placed as a component of subdomal grafting. The senior surgeon has found that common incorporation of certain maneuvers offers more consistent, aesthetically pleasing, and superior functional outcomes. Careful review of this article may guide the reader to consider the more frequent use of some maneuvers or reduction of other maneuvers to reflect that of a streamlined and higher-volume rhinoplasty practice.