Longitudinal Balance Research Articles

Positional influence of center of masticatory forces on occlusal contact forces using a digital occlusal analyzer

Statement of problemDigital occlusal analyzers allow the recording of dental contact forces. Some authors assume a unique location for the center of contact forces at the position of maximum intercuspation, while others indicate variations in dental contact forces when recorded at different times of the day. Which approach is more appropriate is unclear. PurposeThe purpose of this in vitro study was to analyze whether a change in the balance of masticatory forces influences the location of the center of contact forces and its magnitude. Material and methodsThree different dental casts, selected under dental criteria, were mounted in maximum intercuspation on a semiadjustable articulator equipped with a pattern indicating 9 different force application points (intersection point between 3 longitudinal rows and 3 transverse columns). A force of constant magnitude (169 N) was applied 10 times at each of the application points, and occlusal forces were recorded with a digital occlusal analyzer. Then, two variables were studied: the location of the center of contact forces and its magnitude. Each force application position (9 positions × 3 dental casts=27 in total) was repeated 10 times, and measured data were statistically analyzed with 2-way repeated measures ANOVA (α=.05) test. ResultsThe repeatability of the method indicated that the coefficient of variation mean was 0.37% in the location of the center of contact forces and that its magnitude was 3.70%. The 2-way repeated measures ANOVA test revealed statistically significant variations in the location of the center of contact forces and its magnitude, revealing that longitudinal changes of the application point of masticatory forces affected the magnitude of contact forces and that longitudinal and transverse changes of the application point of masticatory forces affected the location of the center of contact forces. ConclusionsThe location of the center of contact force and its magnitude provided by a digital occlusal analyzer at the position of maximum intercuspation are not necessarily unique to each articulated dental cast. Even if the intensity of the masticatory force remains unchanged, changes in its lateral or longitudinal balance also influence the result of the occlusion forces.

Complementary collective bargaining and firm performance: new evidence for Italian firms

PurposeWithin the two-tier bargaining system, the role of complementary collective bargaining is somewhat controversial. In this paper, the authors analyse collective agreements from a triple perspective: scanning the contents of firm-level complementary collective agreements (CCAs); identifying the factors that determine the probability of signing a CCA and analysing the relationship between the latter and firm performance with a focus on the role of different negotiated topics.Design/methodology/approachThe empirical procedure is based on 2 main linked sources: longitudinal balance sheet data and a cross-sectional dataset of a representative sample of Italian firms with at least 15 employees, including some retrospective information. The innovative dataset derives from integrating multiple sources. The main empirical approaches include Generalized Method of Moments (GMM) estimations, multivariate regressions, as well as instrumental variable (IV) estimations to overcome simultaneity issues.FindingsWith respect to the probability of signing a CCA, on the firms' side, the authors find a positive role of the degree of firm capitalisation and affiliation with an employers' association and a negative role of family firms compared to non-family firms; on the workers' side, a positive role of the workers' unionisation rate and a positive but differentiated weight of workers' union representations and industrial conflicts. With regard to firm performance, the authors' estimates suggest that signing a CCA is associated with an average increase of 3% in total factor productivity (TFP) and 7.8% in labour productivity. By investigating the contents of the complementarity agreements, the authors show that bargaining a wider range of topics implies advantages that are not homogenous, benefitting more efficient firms. Moreover, the authors find a specific positive and significant role for three main interacting issues: economic incentives, organisation and employment.Research limitations/implicationsThe cross-sectional structure of the data on bargaining practices prevents detecting causal relationships due to either potential common driver(s) of both the target variables (firm performance) and bargaining practices (simultaneity bias) and unobservable time-invariant firm-level characteristics (heterogeneity bias).Practical implicationsAccording to the authors' results, policymakers should operate along four fiscal channels to spur the efficiency of firms, via CCA. First, tax incentives stimulate higher firm capitalisation, as this seems to be a CCA-favouring factor. Second, deduction in taxable income for union members, which should led to higher membership rates, hence raising the likelihood of obtaining a CCA. Third, incentives aimed at directly promoting the greater diffusion of CCAs as a source of improved performance. Fourth, fiscal tools aimed at favouring the negotiation of either specific contents or “bundles” of contents, which the authors' estimates show as an additional performance-enhancing tool of CCA practices.Originality/valueThe conceptualisation of the contents of CCA as organisational investments and the whole probability function of signing a CCA are quite innovative. Moreover, the econometric strategy takes account of several potential sources of bias when estimating the relevant coefficients at each stage, which is currently not fully considered in the literature. Finally, this is the first study to shed light on both the diverse outcomes associated with different negotiated topics (in terms of quantity and quality) and the distinction between short and medium-long term effects.

Exploratory pilot study on resource allocation along the dementia continuum under constrained and unconstrained budget scenarios

BackgroundPeople with dementia and their carers have a wide range of health and social care needs which vary along the dementia continuum. The government response to events and transitions at various stages of the continuum can have a substantial impact on the lived experience of dementia and to resource allocation decision-making. Hearing what practitioners have to say about need at various points of transition along the dementia continuum is very important, especially for the resource allocation process.MethodsThe paper uses an innovative longitudinal balance of care (BoC) methodology to identify the impact of changes along the dementia care continuum for care recipients and practitioners throughout the course of the condition. Participatory workshops were held with five Health and Social Care Professionals (HSCPs) to pilot a mixed methods approach to resource allocation decision-making along the dementia continuum. In these workshops, these practitioner participants were asked to generate a set of services and supports for a person with dementia with changing and evolving needs over a five year period under two budget scenarios: no budget constraint (NBC); and a budget constraint (BC). Participants were asked to recommend services for short, post event, transition periods and for longer steady state periods.ResultsParticipants were able to allocate different packages of services and supports for different stages of dementia under different budgetary conditions. The total cost for the five year period under the NBC scenario is €200,000 on average, reducing to €133,000 under the BC scenario. Under the BC (NBC) scenarios, participants spent on average 85% (90%) of their budget on community services and 15% (10%) on nursing home services.ConclusionThe methodology used in this paper is a valuable complement to cross-sectional BoC studies through its identification of the importance of events, transitions and staging along the dementia care continuum. The desire of participants to keep people with dementia living in their own home is strong, even in the later stages of dementia, as evident by their recommendation to spend €400 per week more on home care provision compared to the alternative residential care, albeit in the absence of any budget constraints.

Study on longitudinal stability of ducted vertical take-off and landing fixed-wing UAV

The longitudinal flight stability of the ducted vertical take-off and landing fixed-wing UAV during the flight state of hovering and transition is studied. Firstly, based on the Blade-Element Momentum Theory (BEMT) and experimental data, a coaxial dual-rotor ducted aerodynamic model and a thrust ducted aerodynamic model based on characteristic cross-section calculations are established. The model parameters are identified according to the experimental data. Secondly, a UAV flight dynamics model with thrust duct deflection is established according to the six-degree-of-freedom equations. Finally, the case UAV was used to solve the longitudinal balance and stability analysis of hovering and transition state with the established model method, and compared with the hovering experimental results. The results show that the UAV flight dynamics model combined with the ducted dynamic model established in the article can accurately describe the longitudinal flight stability characteristics of this type of aircraft.

Centre-of-mass and minimal speed limits of the great hammerhead.

The great hammerhead is denser than water, and hence relies on hydrodynamic lift to compensate for its lack of buoyancy, and on hydrodynamic moment to compensate for a possible misalignment between centres of mass and buoyancy. Because hydrodynamic forces scale with the swimming speed squared, whereas buoyancy and gravity are independent of it, there is a critical speed below which the shark cannot generate enough lift to counteract gravity, and there are anterior and posterior centre-of-mass limits beyond which the shark cannot generate enough pitching moment to counteract the buoyancy–gravity couple. The speed and centre-of-mass limits were found from numerous wind-tunnel experiments on a scaled model of the shark. In particular, it was shown that the margin between the anterior and posterior centre-of-mass limits is a few tenths of the product between the length of the shark and the ratio between its weight in and out of water; a diminutive 1% body length. The paper presents the wind-tunnel experiments, and discusses the roles that the cephalofoil and the pectoral and caudal fins play in longitudinal balance of a shark.

舰艇纵倾平衡系统水锤冲击激振特性分析

舰艇纵倾平衡系统水锤冲击激振特性分析

Исследование влияния строительного дифферента малых промысловых судов с большой полнотой корпуса на мореходные качества

The paper highlights the problem of the small trawlers with great block coefficient, despite their optimal architectural and constructive characteristics for fishing in the Baltic Sea. it has been stated that when the expected speeds of the vessel are reached, their towing resistance increases greatly and a significant trim appears on the bow. To clarify the reasons there have been carried out the additional studies of the relation between changes in the landing gear and the towing resistance of the vessel in different modes of movement in order to select the optimum trim for the vessel. The test program included towing tests of a ship model in the speed range 4-12 knots 
 of a full-scale ship with one displacement value and different initial trim values at the stern. It has been inferred that at the stage of designing small fishing vessels (up to 24 meters long) it is advisa-ble to limit the maximum speed to 11 knots, which corresponds to a Froude number ≈ 0.4. Further increase in the speed of the vessel will result in rising a residual resistance coefficient considerably, which will lead to a disproportionate increase in the required power. The residual resistance coeffi-cient of the hull is minimal, provided that the vessel moves at the calculated speed with an even keel, while the optimum angle of the initial trim makes 1.0-2.5 degrees aft. Improper longitudinal balance of small fishing vessels with a large completeness of contours can lead to an increase in re-sidual resistance of up to 30%. The experimental results can be applied to all small fishing vessels with similar block coefficients. It has been recommended to conduct the full-scale tests with differ-ent ship models having various block coefficients in order to define the dependence between the completeness of the vessel and the value of drawdown.

BALANCING AN AIRCRAFT WITH SYMMETRICALLY DEFLECTED SPLIT ELEVATOR AND RUDDER DURING SHORT LANDING RUN

This article investigates methods for balancing aircraft during short straight-line landing run realized by employing split rudder and elevator as air-brakes after touchdown. For standard atmospheric and runway conditions, directional and longitudinal balance equations for aircraft of conventional configuration such as Il-86 are presented. Methods depend on operational and mechanical approaches, where the first requires manual or automatic trim of shortly peaking small pitching, yawing, and rolling moments using dynamic forces while the second suggest some re-design of elevator and rudder control channels to limit deflection angles. The paper describes in detail each method disadvantages and suggests the adoption of automatic operational approach due to less required system modifications and piloting skills.

Broadband upgrade and firm performance in rural areas: Quasi-experimental evidence

This paper analyzes the impact of advanced (up to 20 Mbps download, up to 1 Mbps upload) broadband accessibility on firm performance by exploiting a unique local policy of a staggered broadband infrastructure upgrade across rural municipalities. In a difference-in-differences framework based on longitudinal balance sheet data for limited companies, we show that ADSL2+ availability is associated with increases in firms’ revenue and total factor productivity (by on average 14.8 and 9.1 percent cumulatively over two years), but not with significant changes in personnel cost or employment. Additional analysis of aggregate administrative data shows no significant impact on the total number of active firms or local employment. Pre-trend evaluations support a causal interpretation.

Spectral analysis of centre of pressure identifies altered balance control in individuals with moderate-severe traumatic brain injury

Purpose: To identify impairments and recovery of balance control after moderate-severe traumatic brain injury (TBI) through spectral analyses of static balance tasks and to characterise the contributions of each limb to balance control.Methods: A retrospective analysis of longitudinal balance data from force platforms at 2, 5, and 12 months post-injury in 31 individuals with moderate to severe TBI was performed. Single-visit data from age-matched controls (n = 22) were collected for descriptive comparison. Net and individual limb centre of pressure measures and inter-limb centre of pressure coherence were calculated in low (≤0.4 Hz) and high (≥0.4 Hz) frequencies in the anteroposterior and mediolateral directions during standing with the eyes open and closed.Results: Standing with the eyes closed increased net centre of pressure spectral power in low and high frequencies. Individuals with TBI demonstrated recovery in high frequencies in net centre of pressure in the mediolateral direction. Inter-limb coherence in the anteroposterior and mediolateral directions increased (recovered) over time in high frequencies. Weight-bearing asymmetry was visible in high frequencies in the anteroposterior and mediolateral directions.Conclusions: Increased amplitude of low and high-frequency power suggests that individuals with TBI included in this study have impaired anticipatory and reactive balance mechanisms, which may be driven by weight-bearing asymmetries and which recover over time.Implications for rehabilitationAnticipatory and reactive balance impairments after traumatic brain injury may place individuals at increased risk for falls.Analyses from postural sway in static balance tasks infer changes in anticipatory or reactive balance control after traumatic brain injury.Addressing weight-bearing asymmetries in rehabilitation interventions post-traumatic brain injury may improve between-limb coordination for anticipatory and reactive balance control.

Performance implications of SA8000 certification

PurposeThe purpose of this paper is to shed light on the relationship between the adoption of Social Accountability 8000 (SA8000) – which is considered the most important ethical certification standard – and firm performance, building on agency and contingency theories.Design/methodology/approachThe authors analyse secondary longitudinal balance sheet data of listed firms employing a rigorous event-study approach and compare SA8000-certified companies to different control groups based on three matching criteria, i.e., industry, size, and pre-certification performance. The authors then study the moderating effects of the cultural features, the country’s development level, and the labour intensity on the causal relationship through multiple regression methods.FindingsThe authors find that SA8000 certification positively affects labour productivity and sales performance but has no effect on profitability. Furthermore, the study supports that the relationship between SA8000 and profitability is moderated by two cultural features of the home country of the firms (i.e. power distance and uncertainty avoidance).Originality/valueThis is the first study, which empirically tests the effects of the ethical certification SA8000 on firm performance using a cross-country sample. In addition, the authors contribute to the wider debate on the effects of corporate social responsibility practices on firm performance.

V41. Static sway patterns of individuals with increased risk for, and converters to Parkinson’s disease. Analysis of 700 participants of the TREND-study

Background and aim Quantitative assessment of prodromal presentations (e.g. motor signs, hyposmia, depression, REM sleep behavior disorder) of Parkinson’s disease (PD) may be the key to eventually enable earlier diagnosis of this disease. Recent observations indicate that subtle balance deficits belong to these prodromal presentations. Moreover, the higher the number of risk markers and prodromal presentations an individual combines, the more likely is it that this person gets PD. We therefore hypothesized that individuals with a high number of risk factors for PD, as well as individuals with PD who were assessed two and four years before diagnosis (already) show altered static sway characteristics in this risk and prodromal phase of PD. Methods In the first wave of the longitudinal TREND ( Tu binger evaluation of R isk factors for E arly detection of N euro D egeneration)-study ( www.trend-studie.de ), 657 older individuals with and without risk factors for PD (0 risk factors, N = 315; 1 risk factor, N = 240; 2 risk factors, N = 90; 3 risk factors, N = 12) as well as 35 PD patients without clinical evidence for a balance deficit were investigated. Seven individuals out of the 645 developed PD during the subsequent observation period of four years (PD converters). From these individuals, quantitative sway parameters data of the first as well as of the second wave were included in the analysis. Quantitative balance assessment was performed with the McRoberts Dynaport® sensor at the lower back. Participants were asked to stand for 30 s on foam in semitandem stance (i) with eyes closed and (ii) with eyes open. Parameters of area of sway, velocity, acceleration, JERK and mean power frequency (MPF) of sway were analyzed. Results Under eyes-closed conditions, PD patients had a larger area and a lower MPF of sway, compared to the 0, 1 and 2 risk factor(s) cohorts ( p -values. Conclusion To the best of our knowledge, this is the first study reporting about quantitative cross-sectional balance assessment in a large cohort of individuals at risk for PD, as well as about longitudinal balance assessment in PD converters during their prodromal phase over observation periods of up to four years. Our findings confirm previous results from a smaller study which demonstrated static balance differences between high risk individuals for PD and PD patients which were only visible under most challenging conditions. Moreover, results obtained from the PD converters argue for the potential of quantitative balance parameters as trait and state markers in the prodromal phase of PD. Further implications and potential clinical impact of this will be discussed.

Real-Time Monitoring for Vehicle Brake Temperature Rise in Continuous Long Downhill

A real-time monitoring method for brake temperature rise in continuous long downhill with constant velocity braking is proposed. Longitudinal equilibrium equation and energy balance equation are built, and the proportion of brake dissipation energy in total is analyzed. The influence of velocity on brake dissipation energy is studied, then, the calculation model for brake temperature rise is built with the empirical formula of the proportion of bake absorption energy in dissipation energy. Finally, the undetermined coefficient of the calculation model for brake temperature rise is determined with least square method based on test data. The studies show that temperature rise calculated by the built model is similar to the test data both in magnitude and variation trend.

Gamma Knife surgery of vestibular schwannomas: longitudinal changes in vestibular function and measurement of the Dizziness Handicap Inventory

Gamma Knife surgery (GKS) is one of the methods available to treat vestibular schwannomas (VSs), in addition to microsurgical resection; however, clear information regarding balance function outcomes and the impact of treatment on patients' quality of life over time remains an important clinical need. The purpose of this study was to assess the longitudinal balance outcomes and Dizziness Handicap Inventory (DHI) following GKS for VSs. This was a prospective clinical study of balance outcomes in all patients with VSs treated in the Acoustic Neuroma and Skull Base Surgery Program at a tertiary referral center by the senior author and the Gamma Knife team between June 2000 and May 2008. The main outcome measures included preoperative vestibular testing and postoperative caloric testing performed at 6-month intervals to determine vestibular function. The DHI questionnaires were administered retrospectively to assess the impact of GKS on self-perceived disability. Between June 2000 and May 2008, 55 sporadic VSs were treated. There was a >or= 60-month follow-up available in 27 of these patients, >or= 48 months in 32, >or= 36 months in 38, >or= 24 months in 43, >or= 12 months in 51, and >or= 6 months in 54 (1 patient was excluded from the analysis because the follow-up was < 6 months). Various patterns of changes in vestibular function were observed in either positive or negative directions. A significant difference in total DHI score was seen only in the elderly (> 65 years old) patients pre-GKS compared with post-GKS (t = 1.34, p = 0.05). Longitudinal changes in vestibular function occur over time, with the largest changes seen in the first 6 months after treatment. Potential for clinical intervention, such as vestibular rehabilitation therapy, exists during this interval; however, larger cohorts must be studied to determine the timing and efficacy of this intervention. The statistically significant improvement in the DHI score in the patient cohort > 65 years old treated with GKS suggests that this group may benefit from this option when considering the symptom of dizziness.

Dynamics of equilibrium upset and electromagnetic energy transformation in the geomagnetotail: A theory and simulation using particles. 1. Evolution of configurations in an MHD approximation

The process of equilibrium disruption in the system with a current sheet (CS) under the conditions of small magnetic field component normal to CS, which is induced by an external disturbance, has been theoretically studied within the scope of MHD. In the geomagnetotail, this disturbance can be caused by a tearing instability developing in the more distant tail section, or by a ballooning instability in the tail nearest section, or by a rapid reconfiguration at the magnetopause during the disturbance passage in the solar wind. Locally, in a limited CS section, a longitudinal momentum balance is rapidly (on the Alfven time scale) upset when a fast MHD disturbance, the form of which depends on the presence of CS, passes along the tail. The nonequilibrium temperature, which subsequently evolves through splitting of CS into several current structures, originates on a substantially larger (due to the smallness of the normal field component) time scale. Such a reconfiguration SPONTANEOUSLY develops after the initial equilibrium upset under the action of an external (weak) disturbance. During an analysis within the scope of MHD, this reconfiguration can be described as the well-known process with two pairs of nonlinear waves propagating in both directions from the central sheet plane at constant velocities: these are fast rarefaction waves and the following slow “switching-off” shocks. However, the kinetic theory reveals substantially different relaxation channels. These channels are studied in the second and third work sections, where the kinetic numerical simulation of the problem is presented and the results of this simulation are analyzed.

Structured Design of Integrated Subscriber Line Interface System and Circuit

A structured design of Subscriber Line Interface System and Circuit will be described. A high level synthesis allows extracting overall system and circuit requirements to satisfy the desired specifications, standards, and a robust implementation. For this purpose, first the output driving stage will be analyzed and then, dc, ac, and longitudinal balance feedbacks will be considered. Then based on extracted system specifications, optimum circuit design of line-driver will be described. High-level design of line-driver as the most important circuit block which is optimized for stability, accuracy, area, and power dissipation will be elaborated.

Relationships between exercise capacity and front hoof longitudinal balance in horses

AbstractTo the authors' knowledge, the effect of hoof balance alteration on exercise capacity or performance has not been investigated. With the aim of evaluating the relationships between longitudinal front hoof balance and exercise capacity (lactate vs. speed relationship, run time and stride characteristics), two experiments were undertaken. In the first test the horses, left unshod, performed an incremental speed test in which parameters chosen to evaluate exercise capacity were related to hoof longitudinal balance. In the second part of the study the same group of horses had the length of the toe altered (decreased and increased) with the application of shoes, while the angle of the foot and the height of the foot from the ground remained the same. The relative change in exercise capacity due to the alteration of longitudinal balance was observed. In the unshod experiment, lactate level at the speed of 10 ms-1 (5.0±2.0 mmoll-1) was significantly associated with the angles DC° (angle described by the dorsal cortex with respect to the ground; 50.0±3.2°) and PC° (angle described by the palmar cortex with respect to the ground; 29.6 ± 2.9°), while run time (14.07 ± 1.44 min) was associated with breakover indices (Breakover index1 0.33±0.03; Breakover index2 0.30 ± 0.04 – all values mean ± standard deviation (SD)) (breakover indices were created to express the distance between the point of the toe and the point of the third phalanx relative to the length of the palmar cortex or relative to the distance between the point of the third phalanx and the centre of rotation of the distal interphalangeal joint). These associations have to be judged cautiously because the influence of hoof balance on exercise capacity could be biased by other physiological factors and because hoof balance parameters themselves could reflect the conformation of other anatomical structures far from the phalanges. The selective alteration of front hoof balance in the second part of the study produced a significant difference in blood lactate level only at 6 ms-1 (mean ± SD: La6?m?s-1 0.32 ± 0.39 mmoll-1), with this benefit in terms of lactate level being associated with an increase in stride length (mean ± SD: ΔSL6ms-1 0.01 ± 0.05 m; ΔSL10ms-1 0.112 ± 0.218 m). In conclusion, while higher exercise capacity seemed to be associated with lower DC°, PC° and breakover indices, decreasing the toe length without altering the foot angle was beneficial only in terms of lactate level at the speed of 6 ms-1 for horses with DC° greater than 45°; this benefit was accompanied by a slight lengthening of the stride at both 6 and 10 ms-1.

A radiographic technique to assess the longitudinal balance in front hooves.

The aim of this study was to validate a radiographic technique to measure objectively the longitudinal hoof balance in the horse. Ten left third phalanges (P3) obtained from front hooves and 19 left front hooves were used in order to assess the reliability of the radiographic technique and to identify any effect of rotation or alignment of specimens or distance between the X-ray machine and the radiographic cassette, in measuring P3s structures and balance related parameters. A rotational support was made to hold specimens in order to standardise some of the conditions of X-raying. The main axis of the frog was used as a marker for the sagittal plane of P3. Results showed that single radiographic measurements could have wide limits of agreement with actual measurements of the hoof (gold standard values). In order to limit errors we suggest the use of a combination instead of single parameters to assess balance. Rotation of the hoof is also to be controlled when a measurement of angles is needed. The radiographic technique used in this study can be used to objecticely measure balance parameters considered important in order to assess hoof balance.

Modelling dynamics of glaciers in volcanic craters

AbstractGeneral equations of ice dynamics are re-examined, using scale analysis, in order to derive a simplified thermomechanically coupled model for ice flow and heat transfer in ice caps filling volcanic craters. Relatively large aspect ratios between crater depths and diameters, low surface temperatures and intense volcanic heating are the principal characteristics of such craters. The conventional boundary-layer (shallow-ice) approximation is revised to account for these conditions and, in addition, the variable density of the snow, firn and bubbly ice. Large crater depths and intense bottom melting result in low longitudinal balance velocities, controlled by both shear and longitudinal stresses, and hence small surface slopes. In such situations ice can be assumed to be linearly viscous. A flowline model of the glacier dynamics is developed using this assumption. Explicit predictive formulas for ice-particle trajectories and age–depth relations, thus obtained, suggest that the age of ice at the bottom of glaciers in volcanic craters on Kamchatka Peninsula, Russia, may reach hundreds or thousands of years. Ice cores from these glaciers represent unique climatic and volcanic archives.

Reduction of Blade-Vortex Interaction (BVI) Noise through X-Force Control

Momentum theory and the longitudinal force balance equations of a single rotor helicopter are used to develop simple expressions to describe tip-path-plane tilt and uniform inflow to the rotor. The uniform inflow is adjusted to represent the inflow at certain azimuthal locations where strong Blade-Vortex Interaction (BVI) is likely to occur. This theoretical model is then used to describe the flight conditions where BVI is likely to occur and to explore those flight variables that can be used to minimize BVI noise radiation. A new X-force control is introduced to help minimize BVI noise. Several methods of generating the X-force are presented that can be used to alter the inflow to the rotor and thus increasing the likelihood of avoiding BVI during approaches to a landing.