Longitudinal Stabilization Research Articles

Ulnar Lengthening Using a Half-Ring Sulcated External Fixator for Ulnar Longitudinal Deficiency: A Case Report

Ulnar longitudinal deficiency (ULD) is a rare condition of the upper limbs. Although radius lengthening for radial longitudinal deficiencies (RLD) was found to be successful, no ulnar lengthening for ULD without RLD and hand deformities has been reported. Herein, we present a Bayne type II ULD case report of the ulnar lengthening and gradual reduction of the dislocated radial head in an 11-year-old boy using a half-ring sulcated external fixator. For ulnar lengthening/radial longitudinal traction for radial head reduction, transverse osteotomy in mid ulna was performed and half-ring sulcated external fixator was used for ulnar distraction lengthening. Radial longitudinal traction and stabilization of external fixator were achieved by transverse pins through ulna and radius. Distraction (1 mm/day) began at 5th day and was completed at 95th postoperative day. External fixator was applied for 7 months. Successful ulnar lengthening (81 mm; 62% gain) was achieved 1-year after the surgery and the range of elbow motion at 2 years was >40°. Forearm rotation and wrist extension/flexion were also preserved with no complaints of pain. We concluded that ulnar distraction lengthening and gradual reduction of radial head could improve appearance of the arm and were of significant benefit to the patient.

Stabilization control of a bumblebee in hovering and forward flight

Our previous study shows that the hovering and forward flight of a bumblebee do not have inherent stability (passive stability). But the bumblebees are observed to fly stably. Stabilization control must have been applied. In this study, we investigate the longitudinal stabilization control of the bumblebee. The method of computational fluid dynamics is used to compute the control derivatives and the techniques of eigenvalue and eigenvector analysis and modal decomposition are used for solving the equations of motion. Controllability analysis shows that at all flight speeds considered, although inherently unstable, the flight is controllable. By feedbacking the state variables, i.e. vertical and horizontal velocities, pitching rate and pitch angle (which can be measured by the sensory system of the insect), to produce changes in stroke angle and angle of attack of the wings, the flight can be stabilized, explaining why the bumblebees can fly stably even if they are passively unstable.

Flight stabilization control of a hovering model insect

The longitudinal stabilization control of a hovering model insect was studied using the method of computational fluid dynamics to compute the stability and control derivatives, and the techniques of eigenvalue and eigenvector analysis and modal decomposition, for solving the equations of motion (morphological and certain kinematical data of hoverflies were used for the model insect). The model insect has the same three natural modes of motion as those reported recently for a hovering bumblebee: one unstable oscillatory mode, one stable fast subsidence mode and one stable slow subsidence mode. Controllability analysis shows that although unstable, the flight is controllable. For stable hovering, the unstable oscillatory mode needs to be stabilized and the slow subsidence mode needs stability augmentation. The former can be accomplished by feeding back pitch attitude, pitch rate and horizontal velocity to produce delta[symbol: see text] or deltaalpha(2); the latter by feeding back vertical velocity to produce deltaPhi or deltaalpha(1) (deltaPhi, delta[symbol: see text], deltaalpha(1) and deltaalpha(2) denote control inputs: deltaPhi and delta[symbol: see text] represent changes in stroke amplitude and mean stroke angle, respectively; deltaalpha(1) represents an equal change whilst deltaalpha(2) a differential change in the geometrical angles of attack of the downstroke and upstroke).

Ligamentoplasty of the forearm interosseous membrane using the semitendinosus tendon: anatomical study and surgical procedure

Total longitudinal disruptions of the interosseous membrane can allow proximal radius migration and are seen in Essex-Lopresti lesions. We propose an original technique of ligamentoplasty using the semitendinosus tendon. The graft corresponds to the forearm rotation axis for an optimized isometry and longitudinal stabilization. Our ligamentoplasty technique was performed on ten fresh frozen right forearms. We successively assessed the innocuousness, efficiency and resistance of the ligamentoplasty. The ligamentoplasty induced neither passive limitation of pronation-supination nor neurovascular lesions. It prevented from radius proximal migration. The mean load to failure was 28 kg at both ulnar and radial sides of the graft. Our technique is original for the type and position of the graft. It seems safe, efficient and resistant enough for in vivo procedures. This technique decreases longitudinal loads on the radius. It should be indicated in patients with Essex-Lopresti syndrome, in association with radial head internal fixation or arthroplasty.

Stability of GMR heads biased utilizing patterned exchange tabs

We have demonstrated the fabrication of a spin-valve head with a CoFe∕PtMn antiferromagnetic (AFM) exchange-biasing layer for longitudinal stabilization. The application of Golden field annealing means the two AFM layers can be made of the same material with the same TB. The AFM layers may then be chosen to optimize pinning strength, corrosion resistance, etc. The transfer curve based on a pattered head structure with PtMn AFM stabilized free layer is smooth and free of any hysteresis. The head also has good linearity and bias point, and the performance is comparable with the standard abutted permanent magnet junction stabilization. Further optimization is expected to improve the performance, enabling an areal density of >120Gb∕in.2

Gain-Scheduled Stabilization Control of a Unicycle Robot

In this paper, the posture stabilization and longitudinal motion control of a unicycle robot is presented. This unicycle robot has two gyroscopes acting as an actuator for the lateral stabilization and a wheel as an actuator for the longitudinal stabilization. The system is modeled based on Lagrangian Dynamics and system identification method. A gain-scheduled robust control method is applied to enhance its disturbance attenuation ability so as to achieve better performance in posture stabilization and longitudinal motion control. Satisfactory experimental results are obtained.

Spin-valve and tunnel-valve structures with in situ in-stack bias

The use of in-stack longitudinal magnetic stabilization for spin-valve and tunnel-valve recording head sensors has been investigated. An in-stack ferromagnetic layer pinned with an IrMn antiferromagnet is used to magnetostatically stabilize the free layer by flux closure. The use of IrMn with lower blocking temperature than PtMn allows the bias layer to be set independently from the PtMn-pinned reference layer in the spin-valve or tunnel-valve. A Ta spacer 10-30 /spl Aring/ in thickness is used to separate the free layer from the bias layer resulting in low coupling fields. IrMn delivers up to 0.34 erg/cm/sup 2/ of pinning strength, resulting in stable unshielded sensor operation for device sizes below 0.2 /spl mu/m.

Effect of nonplanar shields on the readback performance of GMR heads

Summary form only given. As recorded track widths become narrower, track and head edge geometry becomes more important. We studied the shape effects of the leads and permanent magnets used for longitudinal stabilization located at the edges of GMR sensors. These cause the top shield to curve away from the bottom shield, significantly increasing the read gap at the GMR sensor's edges. This should decrease the shielded sensor's spatial resolution. The on and off track signal profiles have been studied for sensors with lead overlay structures. The effects of lead overlay amount on the readback performance is studied.

Multicriterial Optimization of the Operation and Design Parameters of Electric-Arc Plasmatrons of Linear Circuits

A new method of design synthesis of electric arc heaters by prescribed characteristics is suggested. The method has been applied for multicriterial optimization of the conditions of burning an arc with longitudinal eddy stabilization by an air flow in a plasmatron channel.

Design and commissioning of third harmonic cavities at BESSY II

We report on the design and commissioning of passive third harmonic cavities that have been installed in BESSY-II, a third generation high brightness synchrotron light source. Four cavities were installed to lengthen the electron bunches and increase the beam lifetime which is dominated by large angle intrabeam (Touschek) scattering. During routine user operation the system is running stable in a low power mode resulting in a current dependent bunch lengthening of up to a factor of 1.4, resulting in a significant improvement of beam lifetime. We also observed longitudinal stabilization of the beam using the cavities without the use of longitudinal feedback.

Statistical learning theory and randomized algorithms for control

The topic of the present article is the use of randomized algorithms to solve some problems in control system designs that are perceived to be difficult. A brief introduction is given to the notions of computational complexity that are pertinent to the present discussion, and then some problems in control system analysis and synthesis that are difficult in a complexity-theoretic sense are described. Some of the elements of statistical learning theory, which forms the basis of the randomized approach, are briefly described. Finally, these two sets of ideas are brought together to show that it is possible to construct efficient randomized algorithms for each of the difficult problems discussed by using the ideas of statistical learning theory. A real-life design example of synthesizing a first-order controller for the longitudinal stabilization of an unstable fighter aircraft is then presented to show that the randomized approach can be quite successful in tackling a practical problem.

Robust flight control systems - A parameter space design

This paper deals with the longitudinal dynamics stabilization, around a trim condition, of an aircraft with unsatisfactory longitudinal stability characteristics. This problem is a single-input control problem because only elevator and canards deflections are used as control inputs, and they are simultaneously driven by the same control signal. To this aim, a new linear parameterization of all compensators stabilizing a given single-input plant is proposed, along with a design method based on a computationally tractable procedure for the robust stability analysis of polynomials with at finely dependent coefficient perturbations. Since scale factor sensor changes are perturbations entering affinely the characteristic polynomials coefficients of the closed-loop system, a controller will be synthesized in order to guarantee that the closed-loop poles lie in a specified domain of the complex plane prescribed by MIL specifications, and to achieve robustness against scale factor sensor failures. An application of the proposed procedure to the F4-E military aircraft is presented.

Better Dynamic Closed Loop Control of the PSB RF Accelerating System

The introduction of pulse-to-pulse modulation1) (PPM) in the Proton Synchrotron Booster (PSB) requires that a large number of settings be changed on a pulse-to-pulse basis, imposing a very heavy load on the control system and the operators. Many systems, originally not designed for this type of operation, have to be modified either to accept new settings every cycle (values to be adjusted by the operators, switching to be performed by the control system), or to be self-adaptive, i.e. automatically adjusting to the required conditions. The second approach seems preferable, if feasible without excessive increase in complexity or decrease in reliability. In some cases it was actually possible to reduce the complexity and increase the reliability. This paper deals with the modifications in the beam control system. While reviewing the system's design, additional improvements were found to be possible at moderate cost: they were also, or will be, introduced, and are mentioned accordingly. Mention is made also of a relatively simple method of longitudinal stabilization which has been tested at the PSB.

28—THE EFFECT OF STEAMING ON THE LONGITUDINAL STABILITY OF WOOL YARN

An account is given of an investigation of the effectiveness of steaming on the longitudinal stabilization of wool yarn. Specially prepared worsted yarns were used to study the effects of initial regain and of time and temperature of steaming. Of the several different mechanisms proposed for the longitudinal stabilization of yarn by steaming, only permanent setting is demonstrated directly, and the effects of temperature, initial regain, and time of treatment are established. Two threshold values were observed below which no permanent setting took place—an Initial-regain threshold of 7–8% and a temperature threshold of about 88°C. It is considered possible that the threshold temperature is a function of the particular release treatment used and that it would increase with increasing severity of the conditions of release. The contribution of permanent setting to the over-all longitudinal stabilization was apparently small, but this may have been a result of using a rather severe release treatment.

INTEGRAL KINETIC EQUATIONS OF THE THEORY OF MONATOMIC GASES IN THE PRESENCE OF AN EXTERNAL FIELD OF THE FORCES OF MASS

From these conditions, we may find the parameters of stream flow for different allowable values of #o and v In particular, when #0 = 0 we have a thermally insulated plate. Figure 3 gives curves, which were ca]culated with the help of high-speed digital computer for case a for various values of ft and n. 4. We conclude with a discussion of a process of the same nature which can occur during longitudinal stabilization of a gas discharge in the presence of a large pressure when the magnetic Reynold's number is large. In this case, the magnetic Reynold's number has a role which is precisely analogous to that of an ordinary Reynold's number in the case analyzed in the foregoing: compressed by a large convective stream which is a good internal conductor of electric current, heat sources will be concentrated near the discharge axes in a narrow region, having a thickness of the order of d « L/\/Ee ra; further away from the axes will extend a wider region of the thermal layer, .containing no currents and described by Eq. (7). Heat generated by

U.S. Patent Specifications

A combined longitudinal control and stabilization mechanism, for an airplane provided with a control stick, comprising split flaps, a single cam to operate the said flaps for purposes of longitudinal and stabilization control, said single cam being actuated by the control stick by means of the movement of a shaft, for purposes of elevational control, and means mounted on the control stick whereby the shaft may be rotated independently of the control stick for purposes of stabilization.