Rod Set Research Articles

Fuelless On-Orbit Assembly of a Large Space Truss Structure Using Repulsion of the Service Spacecraft by Robotic Manipulators

A servicing spacecraft motion control approach for the problem of on-orbit truss structure assembly is developed in this paper. It is considered that a cargo container with a rod set and servicing spacecraft are in orbit initially. The assembly procedure is based on spacecraft free-flight motion between the structure’s specified points. The spacecraft is equipped with two robotic manipulators capable of attaching to the structure and holding rods. In addition, the spacecraft can repulse from the structure with a given relative velocity using a manipulator, so the spacecraft and the structure receive impulses. The repulsion velocity vector is calculated in order to reach the structure target point to deliver and install the rod into the truss structure, or to reach the cargo container and take a rod. The problem of searching the repulsion velocity is formulated as an optimization problem with constraints, taking into account the limited value of the repulsion velocity, collision avoidance with structure, restrictions on the angular velocity and translational motion of the structure in the orbital reference frame. This problem is solved numerically with an initial guess vector obtained analytically for simplified motion cases. The application of the proposed control scheme to the assembly of a truss-based antenna is demonstrated. It is shown that the servicing spacecraft is successfully transferred between the structure points by means of manipulator repulsion. Main features and limitations of the assembly problem using a spacecraft with two manipulators are discussed.

Experimental investigation on the optimal control of vortex shedding of a circular cylinder with rotating rods at moderate Reynolds numbers

This paper presents an experimental study of fluid–structure interaction conducted at Reynolds numbers around 104 with scale models in a water channel. A circular cylinder was equipped with eight control rods positioned around its perimeter to interact with the external flow. Each rod could be driven independently to rotate about its axis. The controlled rotation of the rods interfered with the vortex generation mechanism mitigating the formation of a coherent wake. The results showed that it is possible to simultaneously reduce the mean drag and fluctuating lift forces when the rods rotate at a uniform speed or with each rod set at a different rate. A multi-objective genetic algorithm was employed to find the optimum rotation speeds. The optimum rotation produced a more significant reduction in both objectives and also consumed less energy. The contribution of each rod depends significantly on its angular position around the body and the flow conditions resulting from the upstream control rods. The present work clarifies the physical principles of the phenomenon and paves the way for the development of technological applications.

Modelling some rod set imperfections of a quadrupole mass filter.

The problem of modeling the mass peak shape of a quadrupole mass filter (QMF) with round rods is considered. A number of factors leading to the degradation of the mass peak shape are studied, namely, displacement of the electrodes with respect to their original position, changes in the diameter of the electrodes, and asymmetry of the supply potentials. Decomposition of the rod set field on multipole fields allows to obtain an analytical representation of the ion motion equations. Simulations have shown that a parallel shift of one or two electrodes leads to a shift of the peak along the mass number axis and dips at the peak apex. Unbalance of supply voltages does not significantly distort the peak shape, but it shifts the peak along the mass axis and creates a jump of the quadrupole offset potential proportional to the relative unbalance of X and Y rods potentials.

Dipole and quadrupole resonance excitation in linear quadrupoles.

In the development of commercial quadrupole mass spectrometers, there is an interest in improving the performance characteristics such as transmission, resolution, and mass range. In particular, parametric and dipolar resonance excitation of trapping ions are used for linear quadrupole mass filters. Theoretical methods and numerical simulation of ion trajectories were applied for study of ion-optical properties. The review is devoted to description of different excitation methods to improve QMF performance and consists of three parts. The first part presents the results of a linear ion trap simulation for various operating conditions and excitation methods. The second part considers the effects of dipole excitation (DE) on the performance of the quadrupole mass filter. The last part analyzes the formation of stability islands by different methods of quadrupole excitation. To date conditions of mass separation in quadrupole mass filters with sin wave supply were described for stability islands of the first and third stability regions formed by quadrupole and DE. By complicating the electronics such methods allow to overcome the destructive influence of electric field distortions and obtain a resolving power and ion transmission efficiency comparable with commercial devices. At quadrupole resonance excitation by a two-frequency signal, it is possible to reduce the length of electrodes three times without losses in resolution and transmission, which reduces the cost of rod set production with micrometer accuracy. Dipole resonance excitation allows controlling the shape of the mass peak by changing amplitude and phase of the auxiliary AC signal. The main factors affecting the resolving power of a linear ion trap are described theoretically. The numerical modeling results are confirmed by experiment.

The psychophysics of affordance perception: Stevens' power law scaling of perceived maximum forward reachability with an object.

The literatures on affordance perception and psychophysics are seminal in the basic study of perception and action. Nevertheless, the application of classic psychophysical methodologies/analysis to the study of affordance perception remains unexplored. In four experiments, we investigated the Stevens' power law scaling of affordance perception. Participants reported maximum forward reaching ability with a series of rods (both seated and standing) for themselves and another person (confederate). Participants also reported a property of the rod set that has been explored in previous psychophysical experiments and changes in equal measure with forward reach-with-ability (length). In all, we found that affordance perception reports (β = .32) were an underaccelerated function of actual changes in reaching ability compared with relatively less accelerated length reports (β = .73). Affordance perception scaled with stimulus magnitude more similarly to brightness perception than length perception. Furthermore, affordance perception reports scaled similarly regardless of the actor (self and other), task context (seated and standing), or idiosyncrasies of the measurement procedure (controlling for distance compression effects), while length perception reports were sensitive to location/distance compression effects. We offer empirical and theoretical considerations, along with pathways for future research.

Reactivity disturbance suppression method for small modular reactors based on core coolant flow control

Small modular reactors (SMR) have an exceptionally wide range of applications due to their flexibility. But the reactivity of SMR is more susceptible to disturbance than that of large commercial reactors, which may cause the core power to deviate from the set value, and the limited internal space makes it difficult for SMR to compensate or adjust for reactivity disturbance by setting a sufficient number of control rods as in large commercial reactors. Therefore, in order to improve the operational stability of SMR, a method is proposed to indirectly change the nuclear fuel temperature by adjusting the coolant flow rate and thus compensate the reactivity disturbance by the Doppler effect of nuclear fuel resonance absorption. Simulation experiments show that the method can effectively eliminate reactive disturbances that cannot be completely eliminated by control rods under the conditions of restricted SMR space and limited number of control rod sets, thus providing operational stability of SMR.

Coupling a Gaussian input beam to a quadrupole mass filter with round rods

We consider an input ion beam that has Gaussian distributions of the initial ion coordinates and transverse velocities at the entrance of a quadrupole mass filter (QMF) with round rods. To calculate the statistical QMF acceptance, an ion trajectory method has been used. The probability density functions of accepted points on phase planes of transverse ion positions and velocities in the X and Y directions are used to visualize the distributions of phase space points. To determine the statistical acceptances we calculate the second moments of the probability density functions. We define the statistical acceptance of the quadrupole mass filter as the area of an ellipse on the phase plane determined by the second moments. The values of the second moments characterize the efficiency of the coupling of the Gaussian ion source and the acceptance of a quadrupole rod set with round rods. The above approach is a supplement to a previously published theoretical model of QMF fields with circular electrodes.

Extended magnetohydrodynamics simulations of thin-foil Z-pinch implosions with comparison to experiments

Cylindrical foil liners, with foil thicknesses on the order of 400 nm, are often used in university-scale Z-pinch experiments (∼1 MA in 100 ns) to study physics relevant to inertial confinement fusion efforts on larger-scale facilities (e.g., the magnetized liner inertial fusion effort on the 25-MA Z facility at Sandia National Laboratories). The use of ultrathin foil liners typically requires a central support rod to maintain the structural integrity of the liner target assembly prior to implosion. The radius of this support rod sets a limit on the maximum convergence ratio achievable for the implosion. In recent experiments with a support rod and a pre-imposed axial magnetic field, helical instability structures in the imploding foil plasma were found to persist as the foil plasma stagnated on the rod and subsequently expanded away from the rod [Yager-Elorriaga et al., Phys. Plasmas 25(5), 056307 (2018)]. We have now used the 3D extended magnetohydrodynamics simulation code PERSEUS (which includes Hall physics) [C. E. Seyler and M. R. Martin, Phys. Plasmas 18(1), 012703 (2011)] to study these experiments. The results suggest that it is the support rod that is responsible for the helical structures persisting beyond stagnation. Furthermore, we find that as the radius of the support rod decreases (i.e., as the convergence ratio increases), the integrity and persistence of the helical modes diminish. In the limit with no support rod, we find that the structure of the final stagnation column is governed by the structure of the central precursor plasma column. These simulation results and their comparisons to experiment are presented.

Development and Application of Universal Hanging line Fixtures for 66-220kV Pointed cross-head

For traditional fixtures, replace insulator string conductors as horizontal side hanging points in the linear pole tower of the transmission line. Its versatility is not strong, when using the wire rod and soft slings or carriages can not be shared and other limitations. The development of a Universal Hanging line Fixtures for 66-220kV Pointed cross-head is proposed. First of all, the fixtures span can be adjusted by adjusting the bolts, so as to better avoid all kinds of cross-burden head bolts, and cross on the joint plate and the cross-load bolt. Makes it stable. Secondly, fitting the wire rod directly in the slot at the hanging points at both ends of the mount and lifting with a wire rod depends on the needs of the lifting wire. You can also install a pin rod in the trailer, the carriage set or tight-line soft sling hanging on the pin rod, with the carriage or soft sling lifting. Solved the problem when replacing the insulator with pointed cross-heads, the generality of the wire lifting is not good. And the wire rod and carriage set and soft sling between the lifting tool interchange.

A comparison based digital waveform generator for high resolution duty cycle.

A comparison-based digital waveform generator has been developed that directly enables purely duty cycle controlled digital mass filters. This waveform generator operates by the comparison of a periodic waveform and a DC level to produce a digital waveform. The improved duty cycle realized by this method of waveform generation is demonstrated by producing a mass spectrum of electrosprayed lysozyme by varying the duty cycle of a digital waveform applied to a quadrupole rod set. Operation and control of the waveform generator using an inexpensive open-source microcontroller is discussed.

キンク損傷を有するPBO繊維の疲労強度特性

In this study, fatigue strength properties of PBO (Poly-p-Phenylene Benzobisoxazole) fiber with kinking damage were investigated in monofilament fatigue tests. Two types of the PBO fibers were used in the experiment. One was the conventional type (AS fiber). The other was high-modulus type (HM fiber) with a higher crystal orientation than AS fiber. Kinking damages was created on surface of virgin fiber by winding bundle fibers to steel rod set to 0.625 mm. Load-controlled fatigue tests were carried out using a sinusoidal load with frequency 10 Hz and stress ratio of R = 0.5, and the load cell capacity was 10 N. It was found that fatigue strength with kinking damage was lower than that without kinking damage in neither AS fiber and HM fiber. Fatigue strength decrease of AS fiber and HM fiber with kinking damage in a low cycle area was larger than that in a high cycle area. The fatigue fracture of PBO fiber with kinking damage presented the different aspect at a high cycle area and a low cycle area in neither AS fiber and HM fiber.

Does a positioning rod or a patient-specific guide result in more natural femoral flexion in the concept of kinematically aligned total knee arthroplasty?

Flexion of the femoral component in 5° increments downsizes the femoral component, decreases the proximal reach and surface area of the trochlea, delays the engagement of the patella during flexion, and is associated with a higher risk of patellar-femoral instability after kinematically aligned TKA. The present study evaluated flexion of the femoral component after use of two kinematic alignment instrumentation systems. We determined whether a distal cutting block attached to a positioning rod inserted perpendicular to the distal femoral joint line in the axial plane and 8-10cm into the distal femur anterior and posterior to the distal cortex of the femur in the sagittal plane or a femoral patient-specific cutting guide sets the femoral component in more natural flexion. Flexion of the femoral component was measured with respect to the sagittal femoral anatomic axis of the distal diaphysis and the sagittal femoral axis on rotationally controlled long-leg lateral computer scanograms. Measurements were performed on 53 consecutive patients treated with a kinematically aligned TKA performed with a distal cutting block attached to a positioning rod, and 53 consecutive patients treated with a kinematically aligned TKA performed with a femoral patient-specific cutting guide. The average flexion and variability (±standard deviation) of the femoral component of patients treated with a positioning rod was 1°±2° and 7°±4° with respect to the anatomic and mechanical axes, respectively, which was 5° less than the average flexion of the femoral component of patients treated with a femoral patient-specific cutting guide of 6°±4° and 12°±5° (p=0.0001, p=0.0001, respectively). Because a distal cutting block attached to a positioning rod sets the femoral component in 5° less flexion and with less variability than a femoral patient-specific cutting guide, we prefer this instrumentation system when performing kinematically aligned TKA to reduce the risk of patellar-femoral instability. Each surgeon should determine the repeatability of setting the flexion of the femoral component with this instrumentation system.

Dipolar excitation in the third stability region.

Dipole resonant excitation of ions creates instability bands which follow iso-β lines where β is the characteristic exponent (stability parameter). Instability bands are exited most effectively on the fundamental frequency π= βΩ/2. Here π is the angle resonance frequency of the dipolar voltage applied to x or y pair rods of the analyzer, and Ω is the angle frequency of the main drive voltage. Our goal is to study the mass peak shape in the third stability region with dipolar resonance excitation of the instability band with respect to the resonance frequency π and the dipolar potential amplitude. Numerical integration of the ion motion equations with a given ion source emittance is used to investigate peak shapes and ion transmission. We show that it is possible to vary the resolution power at any part of the third stability region. A change of the dipolar potential phase leads to a periodical variation of the resolution with period π.The most effective dipolar excitation in the y direction is along βy near the stability boundary. The mass peak shape is calculated also for a quadrupole with round rods. The best peak shape (small tails and high resolution) takes place for the rod set with r/r0=1.130. Dipolar excitation increases the transmission by approximately 5-10% at a given resolution.

Femtosecond laser enhanced current in a thermionic diode with barium vapor

We studied the signal from a thermionic diode when a femtosecond laser beam was spatially overlapped by an excimer pumped dye laser beam. The nanosecond dye laser was scanned from 435 to 438nm in order to excite the autoionizing levels of barium by two photon absorption. The broadband ultrashort laser light was centered at 427nm, which is also above the first ionization limit of barium. The bias voltage between the cell body and the tungsten rod (set at either 9 or 0V) was used to collect electrons after the barium ions had been created by multiphoton (auto) ionization. The overall background of the thermionic signal was appreciably elevated due to the two photon ionization by the broadband femtosecond laser. We measured the thermionic signal with and without femtosecond laser overlap, and with a biasless and biased thermionic diode. The effect of the femtosecond laser was appreciable enhancement of the background ionization continuum. This was especially visible in the presence of noble gases at pressure of 50mbar. Argon produced the largest and helium produced the smallest enhancement in the background continuum. In addition, we observed a few broad spectral features of a presumably collision induced nature.

Cavitation by spall fracture of solid walls in liquids

Experiments are carried out to investigate the cavitation process induced by the spill-off from material from a surface in a liquid environment. Therefore, a simplified physical model was designed which allows the optical observation of the process next to a transparent glass rod submerged in a liquid where the rod is forced to fracture at a pre-defined groove. High-speed shadow-imaging and refractive index matching allow observation of the dynamics of the cavitation generation and cavitation bubble breakdown together with the flow. The results show that the initial phase of spill-off is a vertical lift-off of the rod from the surface that is normal to the direction of pendulum impact. A cavitation bubble is immediately formed during spill-off process and grows in size until lateral motion of the rod sets in. While the rod is transported away, the bubble shrinks into hyperbolic shape and finally collapses. This process is regarded as one contributing factor to the high efficiency of hydro-abrasive wear.

A15 熱交換器性能試験用2シリンダー対向配置α型スターリングエンジンの設計製作(スターリングサイクル機器及び関連要素と応用システム(1))

A 2-cylinder opposite-positioned alpha-type Stirling engine for testing the heat exchangers, including the heater, cooler and regenerator, is being under construction. It is composed of two alpha-type Stirling engines with the two expansion cylinders and the two compression cylinders being respectively opposite-positioned on the same horizontal plane by using a master-and-slaves connecting rod set, resembling a radial engine with four cylinders. Such a configuration as well as the three external heat exchangers makes it convenient to replace and/or test any one or any combination of these heat exchangers on one hand, and on the other hand, avoiding the interference of various measuring instruments possibly used in the future.

Duty cycle-based isolation in linear quadrupole ion traps

Simulation and matrix methods were used to determine the change in the minimum trapping frequency during duty cycle base waveform manipulation to provide axial trapping. Duty cycle based axial trapping sets both rod sets of a digitally driven linear quadrupole to the same potential thereby nullifying the radial trapping field for a definable interval during the waveform cycle. Turning off the radial trapping field affects the ion motion. Consequently, the ion stability conditions and the secular frequency change with duty cycle during axial trapping. The work presented here demonstrates the change in the ion motion by simulating the ion trajectories under duty cycle base trapping conditions and determining the change in the minimum trapping frequency as a function of the change in duty cycle. The change in the stability conditions with duty cycle was determined by matrix methods. These calculations were used to determine the minimum trapping frequency change with duty cycle and validate the simulations. They were then used to discuss the duty cycle effects and propose methodology for using duty cycle waveform manipulation to perform precise ion isolation. Finally, matrix methods were used to show that ion isolation can be performed concurrently with duty cycle based axial trapping. These results were confirmed by simulation.

Transfer of calibration in dynamic touch: What do perceivers learn when they learn about length of a wielded object?

Successfully performing everyday behaviours requires that perceptions and actions are properly calibrated to environmental properties. In three experiments, the authors tested whether calibration was specific to perception of a particular property of a wielded object from a particular grasp position on that object. The experiments investigate whether transfer of recalibration occurs across changes in grasp position (Experiment 1), object property (Experiment 2), and grasp position and object property (Experiment 3). The results suggest that a complete transfer of recalibration occurred in each case. Such results are consistent with recent research on dynamic touch and suggest that rather than recalibrating participants to one particular property of the wielded objects, feedback about a particular property served to recalibrate participants to the properties of the rod set as a whole.

Distribution into the quadrupole mass filter with round rods

Abstract Potential field distribution of a quadrupole mass filter with circular cross-section electrodes is described. At first, using superposition principle, we calculate potential around a round rod which is subjected to a given potential. By standard separation method, we then able to obtain the potential distribution into the quadrupole mass filter with circular rods. The results are compared with those obtained with a conventional hyperbolic rod set. Also, the results show that, for the same equivalent operating point in two stability diagrams (having the same β y ) the associated modulated secular ion frequencies behavior are the same.

Research and Application of New Inserted Shape Memory Alloy Actuators

More and more people prefer a new inserted shape memory alloy actuator (ISMAA) to a traditional SMA actuator because there are some advantages in ISMAA, such as precise control abilities, high response, broad range of performance, and so on. An elastic rod and two SMA wires, which are inserted in parallel with the axis of the rod, make up the actuator. The actuating wire, which is one of the two wires, is superposed along the rod's axis and set to memorize a “U” shape. The restoring wire, which is the other of the two wires, is placed off-axially and memorizes a straight shape. In the actuator, there are also two differential stain meters, which are placed at an apt location referring to the actuator's bending direction. By making use of these two meters, accurate position control comes true. Taking advantage of the coordinating martensite fraction coefficients appropriately, the presence of major and minor hysteresis loops can be explained in detail when the analytical model was established. The actuator can be optimized by combining the analytical model with the experimental results, particularly the structural parameters, such as the wire's recoverable curvature, wire's radius, rod's radius, and offset distance. In order to take into account the basic performance, there is an example of an anthropopathic robot hand, which is composed of six ISMAAs.