Small Radial Dimension Research Articles

Кинематика волновых зубчатых передач с генератором волн внешнего деформирования

The development of automatic control systems, tracking systems and industrial robotics requires the creation of new generation drive systems with high efficiency, kinematic accuracy, reliability, durability with small axial and radial dimensions and weight. To implement tracking systems with power differentials, transmission mechanisms with two degrees of freedom are required to provide the transformation and summation of two movements of drive motors into the required movement of the drive output shaft. These requirements in single-channel tracking systems are well met by strain wave gears (SWG) with low-inertia disk and ring wave generators. They allow for wide layout possibilities, the ability to route cables through the hollow central shaft of the drive, high torsional rigidity and low moments of inertia, which are in the range of 250 to 400 times less than those of cam wave generators, thus ensuring high drive speed. There are practically no publications, except domestic ones, devoted to the study of SWG with ring wave generators. This scientific direction of research is carried out at the Bauman Moscow State Technical University. Structural schemes of SWG with ring generators of external deformation waves are considered, the features of the kinematics of these gears are studied, and recommendations for improving their quality indicatorsare proposed

A high power capacity Ka-band radial transit time oscillator with one-gap extraction cavity

The radial transit time oscillator (RTTO) is promising to realize high power output of millimeter-waves. Although the radial structure can enhance the power capacity, less cavities and small radial dimension make it difficult to improve the power capacity in RTTOs, especially in the extraction cavity. A one-gap extraction cavity in the Ka-band RTTO is proposed in this paper to improve the power capacity. Without electrons, taking the TM011 cavity as an example, the radial reversal resonant electric field can intersect with radial electrons. By choosing the sizes of the cavity, the synchronization of the electrons and the electric field can be realized to achieve effective energy exchange. In particle-in-cell simulation, the RTTO with the TM011 extraction cavity can output 1.0 GW high power microwaves (HPMs) at 31.2 GHz, and the beam-wave conversion efficiency is 31.6%. The maximum electric field in the TM011 cavity is only 800 kV/cm, which is less than one third that in the TM010 extraction cavities. In addition, the TM012 extraction cavity is employed to improve the efficiency to 35.4%. At the same time, because of the increase in the output power, the maximum radial electric field in the TM012 cavity increases to 850 kV/cm. Therefore, the one-gap extraction cavity can realize multiple energy exchanges to get high beam-wave conversion efficiency and enhance the power capacity in the extraction cavity significantly.

Efficiency modelling and analysis for a novel double-arc bevel gear nutation transmission system for pure electric vehicles

Since more attention has been paid to the development of pure electric vehicles, small and high efficiency of transmission system is the trend. The paper proposes a novel double-arc bevel gear nutation transmission system with two inputs and one output for pure electric vehicles. Compared with the traditional planetary gear transmission, the designed system has advantages of compact structure, small radial dimension and low cost. The nutation transmission of double-arc bevel gears is transformed into a spur planetary gear transmission mechanism with few teeth difference when the inclination angle is equal to zero. Based on kinetic and gear meshing analysis, it is found that the transmission efficiency of the model is related to the nutation gear ratio and the speed ratio of two power sources. The approach of analyzing the efficiency proposed in this paper can provide theoretical basis for the efficiency analysis of the nutation transmission in the future.

Elastic hydrodynamic lubrication analysis for a sine movable tooth drive

The sine movable tooth drive has small radial dimension such that the heat, caused by friction, becomes an important factor in deciding its load-carrying ability. It is important to determine the amount of tooth lubrication in order to reduce the heat caused by the friction. This study provides equations for the meshing performance and provides the forces for the sine movable tooth drive. Using these equations, the minimum oil film thickness for the drive system is investigated. Results show that the minimum film thickness between the movable tooth and input shaft or shell changes periodically along the input shaft rotation angle. A large movable tooth radius and a movable tooth rotation radius could increase the film thickness between the movable tooth and the input shaft or the shell. In addition, a large speed ratio could increase the film thickness between the movable tooth and the input shaft, but this would also decrease the film thickness between the movable tooth and the shell. A large sine amplitude could increase the film thickness between the movable tooth and the input shaft, but this does not change the film thickness between the movable tooth and the shell. Under normal operation speeds, the hydrodynamic lubrication condition occurs between the movable tooth and the input shaft, and the partial membrane hydrodynamic state occurs between the movable tooth and the shell.

Temperature self-sensing and closed-loop position control of twisted and coiled actuator

Twisted and coiled actuator (TCA), which is a newly discovered artificial muscle made by twisting and coiling polymer fibers into spring-like structures, can generate great contraction or expansion when heated. The temperature plays an important role in the actuation of TCA since its temperature sensibility. However, it is usually hard to measure the temperature of TCA directly with conventional temperature sensors due to its small radial dimension. A newly developed temperature self-sensing method of TCA is used in this work. Nickel wire, whose resistance varies linearly with the temperature, is combined with the polymer fiber of TCA by twisting and coiling them together. Therefore, the temperature of TCA is evaluated approximately via the resistance of the nickel wire. Based on the temperature self-sensing function, a semi-closed loop position control system without external sensor and a temperature and position dual closed-loop control system which responses 50% faster than the single closed-loop control system are implemented. These works add the temperature self-sensing function to TCA and facilitate its applications especially in small and soft devices.

Texturing Silicon Nanowires for Highly Localized Optical Modulation of Cellular Dynamics.

Engineered silicon-based materials can display photoelectric and photothermal responses under light illumination, which may lead to further innovations at the silicon-biology interfaces. Silicon nanowires have small radial dimensions, promising as highly localized cellular modulators, however the single crystalline form typically has limited photothermal efficacy due to the poor light absorption and fast heat dissipation. In this work, we report strategies to improve the photothermal response from silicon nanowires by introducing nanoscale textures on the surface and in the bulk. We next demonstrate high-resolution extracellular modulation of calcium dynamics in a number of mammalian cells including glial cells, neurons, and cancer cells. The new materials may be broadly used in probing and modulating electrical and chemical signals at the subcellular length scale, which is currently a challenge in the field of electrophysiology or cellular engineering.

Theoretical and Experimental Research of Spherical Roller Transmissions

Передачи с промежуточными телами качения в настоящее время используются для решения специальных инженерных задач. Они имеют низкую материалоемкость и высокую нагрузочную способность, так как передача мощности осуществляется по нескольким параллельным потокам, число которых равно числу тел качения. К недостаткам многих конструкций, препятствующих широкому использованию в промышленности, относят низкий КПД и недостаточную надежность. В статье рассмотрены вопросы расчета и проектирования передач, у которых траектории центров масс тел качения расположены на сферических поверхностях. Ролики взаимодействуют со сферическими кулачками, образующими пространственные замкнутые периодические беговые дорожки. Преимуществами являются небольшие осевые и радиальные габариты, возможность объединения в конструкции одного механизма редукторного узла и угловой муфты. Рассмотрены конструкции сферических роликовых передач, проведен сравнительный анализ двух- и трехзвенных механизмов, представлены результаты силового анализа и произведена теоретическая оценка потерь мощности. Приведены результаты экспериментальных исследований КПД и шумовых характеристик разработанных редукторов. Обосновывается вывод о конкурентоспособности сферических роликовых передач как передач общемашиностроительного назначения в диапазонах передаточных отношений 3…15, частот вращения валов не более 3000 мин-1.

Fabrication, characterization and separation properties of three-channel stainless steel hollow fiber membrane

The industrial applications of stainless steel single-channel hollow fiber (SCHF) membranes were confined by their restricted mechanical strength due to the small radial dimension. A stainless steel three-channel hollow fiber membrane (TCHF) was developed through the non-solvent induced phase separation (NIPS) method and then sintered in inert atmosphere. The combination of low mass transfer resistance of the SCHF membrane with high mechanical strength and large specific surface area of the new configuration enabled the TCHF membrane to overcome the weakness of mechanical strength without compromising other properties. The resultant TCHF sintered at 1100°C showed a N2 permeation of 3.2×10−4mol/(m2sPa) which was one order of magnitude higher than that of SCHF membrane and the fractural loading of 18.2N which was four times higher than that of SCHF membrane. The corrosion resistance tests proved the chemical stability in hostile fluids and the recycle performance confirmed the durability after tough cleaning several times. The rejection of starch wastewater was nearly 85% after a long-term operation, which showed the superior filtration performance. Therefore, stainless steel TCHF membrane exhibited great potentials in versatile applications such as microfiltration, gas separation, and catalytic reaction.

Photon diffusion in a homogeneous medium bounded externally or internally by an infinitely long circular cylindrical applicator III Synthetic study of continuous-wave photon fluence rate along unique spiral paths

This is Part III of the work that examines photon diffusion in a scattering-dominant medium enclosed by a "concave" circular cylindrical applicator or enclosing a "convex" circular cylindrical applicator. In Part II of this work Zhang et al. [J. Opt. Soc. Am. A, 66 (2011)] predicted that, on the tissue-applicator interface of either "concave" or "convex" geometry, there exists a unique set of spiral paths, along which the steady-state photon fluence rate decays at a rate equal to that along a straight line on a planar semi-infinite interface, for the same line-of-sight source-detector distance. This phenomenon of steady-state photon diffusion is referred to as "straight-line-resembling-spiral paths" (abbreviated as "spiral paths"). This Part III study develops analytic approaches to the spiral paths associated with geometry of a large radial dimension and presents spiral paths found numerically for geometry of a small radial dimension. This Part III study also examines whether the spiral paths associated with a homogeneous medium are a good approximation for the medium containing heterogeneity. The heterogeneity is limited to an anomaly that is aligned azimuthally with the spiral paths and has either positive or negative contrast of the absorption or scattering coefficient over the background medium. For a weak-contrast anomaly the perturbation by it to the photon fluence rate along the spiral paths is found by applying a well-established perturbation analysis in cylindrical coordinates. For a strong-contrast anomaly the change by it to the photon fluence rate along the spiral paths is computed using the finite-element method. For the investigated heterogeneous-medium cases the photon fluence rate along the homogeneous-medium associated spiral paths is macroscopically indistinguishable from, and microscopically close to, that along a straight line on a planar semi-infinite interface.

Towards a generic method for inorganic porous hollow fibers preparation with shrinkage-controlled small radial dimensions, applied to Al2O3, Ni, SiC, stainless steel, and YSZ

A versatile method is presented for the preparation of porous inorganic hollow fibers with small tunable radial dimensions, down to ∼250 μm outer diameter. The approach allows fabrication of thin hollow fibers of various materials, as is demonstrated for alumina, nickel, silicon carbide, stainless steel, and yttria stabilized zirconia. The preparation method is based on dry-wet spinning of a particle-loaded polymer solution followed by thermal treatment. Exceptionally small radial dimensions have been achieved by surface energy driven viscous flow of the green fiber, resulting in a reduction of macro-void volume. It is shown that the extent of viscous deformation is directly related to the rheology of the particle-loaded green fiber above the glass transition temperature of the polymer. A particle specific limited concentration range can be identified in which viscous deformation is possible. Above a critical particle volume fraction the viscosity of the particle–polymer material increases sharply and the time scale of viscous deformation becomes too long. Below a minimum concentration of particles it is not possible to sinter the particles together. For small particles of alumina, silicon carbide, and yttria stabilized zirconia the concentration range allowing viscous deformation is very narrow as compared to that of larger metal particles.

A Generic Method for Inorganic Porous Hollow Fibers Preparation with Shrinkage-controlled Small Radial Dimensions

A Generic Method for Inorganic Porous Hollow Fibers Preparation with Shrinkage-controlled Small Radial Dimensions

Porous stainless steel hollow fibers with shrinkage-controlled small radial dimensions

A method is presented for the preparation of thin (∼250 μm) porous stainless steel hollow fiber membranes based on dry–wet spinning of a particle-loaded polymer solution followed by heat treatment. Extraordinarily small radial dimensions were achieved by controlled shrinkage during thermal treatment. Above the glass transition temperature of the polymer, the dynamics of surface energy-driven viscous flow allow regulated reduction of the macrovoid volume, resulting in a substantial decrease in the final fiber diameter.

Research of Rotary Power Head of Drill with Roulette Curve Profile Movable Tooth Transmission

The rotary power head is the most important part of the cutting drill. After researching the status of the rotary power head, we invented a new decelerator—roulette curve profile movable tooth transmission, and applied it in cutting drill, we presented the rotary power head with roulette curve profile movable tooth transmission. The moving components, such as the input shaft and the output shaft, of the roulette curve profile movable tooth transmission are self-balance, so the transmission can bring about random tooth number difference. Analyzing the principle of the transmission, we create the three-dimensional modeling by using Solidworks2010. The rotary power head with the new transmission installed is convenient in assembling and disassembling, transferring bigger torque, having a relatively small radial dimension, suitable for heavy-loaded rock drill machine.

A unique micromechanocalorimeter for simultaneous measurement of heat rate and force production of cardiac trabeculae carneae

To study cardiac muscle energetics quantitatively, it is of paramount importance to measure, simultaneously, mechanical and thermal performance. Ideally, this should be achieved under conditions that minimize the risk of tissue anoxia, especially under high rates of energy expenditure. In vitro, this consideration necessitates the use of preparations of small radial dimensions. To that end, we have constructed a unique micromechanocalorimeter, consisting of an open-ended flow-through microcalorimeter, a force transducer, and a pair of muscle-length actuators. The device enables the metabolic and mechanical performance of cardiac trabeculae carneae to be investigated for prolonged periods in a continuously replenished oxygen- and nutrient-rich environment.

Development of a compact double-disk magneto-rheological fluid brake

SUMMARYThis paper describes the development of a novel compact magneto-rheological (MR) fluid brake with high transmitted torque and a simple structure. The MR fluid brake has two shearing disks with an electromagnetic coil located between them. Such a structure enables the brake to have a small radial dimension and a large torque transmission capacity. In the design process, a Bingham viscoplastic model is used to predict the transmitted torque. Electromagnetic finite element analysis (FEA) is performed to assist the magnetic circuit design and structural parameters' optimization. The novel brake design is prototyped and studied. Experimental results show that a compact MR fluid brake with high transmitted torque is successfully achieved.

Comparison of different techniques for the FLUENT $^{\copyright}$ -based treatment of the electromagnetic field in inductively coupled plasma torches

A new technique for using the CFD commercial code FLUENT\(^{\copyright}\) to simulate inductively coupled plasma torches by means of two-dimensional axisymmetric models is presented. The method is based on an external user-defined function (UDF) which fully solves the electromagnetic field equations, letting the FLUENT\(^{\copyright}\) built-in module calculate only the plasma temperature and velocity fields inside the torch region. In this framework, computations have been carried out for LTE, optica lly thin argon plasmas at atmospheric pressure, using extended grid models with either magnetic dipole or vanishing vector potential boundary conditions for the electromagnetic field. It is shown that our newly developed technique is up to 60% faster on each iteration than that using user-defined scalars (UDS) previously proposed in the literature, as the need of solving flow field equations also outside the plasma zone is eliminated. Calculations are also performed using exact integral boundary conditions for the vector potential, as given by the standard electromagnetic field approach, taking into account the effects of both exciting and induced currents. The corresponding results are compared with the approximate ones obtained by employing extended grid models, showing that for small radial dimensions of the electromagnetic field domain, the magnetic dipole boundary conditions give more realistic solutions than those assuming a vanish ing vector potential.

Review of electron beam macroinstabilities and other EBIS related stability and issues

Plasma magnetohydrodynamics and macroinstability theories are briefly reviewed. Although the configuration of any EBIS is inherently susceptible to a number of classical beam instabilities, the small radial dimension of an EBIS plasma prevents modes from occurring in EBIS traps with low beam compression due to physical limitation. In EBIS devices with high electron beam compression, where the potential for beam instabilities is great, the radial dimension is smaller than the Debye length, which renders any plasma theory invalid. However, a RHIC EBIS is expected to have a diameter which is much larger than the Debye length. Hence, it may be the first EBIS, in which the various plasma theories could be valid. For this and similar future devices, a framework is established to analyze and offer remedies plasma instabilities in EBIS.

Review of electron beam microinstabilities and their relevance to EBIS devices

Plasma kinetic theory and some examples of microinstabilities are briefly reviewed. Although the velocity space configuration of any EBIS is inherently susceptible to a number of classical beam microinstabilities, the small radial dimension of an EBIS plasma may prevent modes from occurring in EBIS traps due to physical limitation. In EBIS devices with high electron beam compression, where the potential for beam microinstabilities is great, the radial dimension is smaller than the Debye length, which renders plasma kinetic theory invalid. Potential for parametric instabilities exists due to coupling of structure excited modes into plasma modes by various mode-mode coupling "decay" processes.

Excimer lasers induced electron beams on metal cathodes under a plasma effect

We studied the electron beam generated from a metal cathode illuminated by XeCl and KrCl excimer lasers below plasma ignition threshold intensities. By Langmuir-like probe measurements, positive potentials of about 0.75 V at distances down to 2 μm from the grounded target above the laser spot area were observed during the laser action. From this result and in the absence of an accelerating voltage, a positive charge near the cathode of about 3.3 mC/m 3 was estimated. The strong charge density modified the accelerating voltage and under space charge regime, the output current was higher than that theoretically calculated. Therefore, under these conditions we solved the 1-D Poisson equation including the influence of the small radial beam dimension. The maximum experimental current density was 80 A/cm 2 with a normalised emittance of 43 (π mm mrad) for an Al target at 40 kV accelerating voltage. Further studies of the plasma influence were performed with a large cross-section laser beam (90 mm 2) and with anode-cathode distances larger and shorter than 90 π (mm) and neglecting the beam enlargement.

The effect of near-crystallization temperature annealing on the electrochemical behavior of amorphous Fe 77.5B 15Si 7.5 fibres in borate buffer

Amorphous alloys are increasingly being utilized in various industrial situations. Most of the studies on electrochemical behavior and corrosion resistance have been on amorphous ribbons, which have two surfaces (shiny side and dull side), with different corrosion behavior. Electrochemical studies on amorphous fibres are relatively few. Crystallization of amorphous materials leads to changes in physical properties, which are of practical benefit. The theoretical and practical importance of the crystallization of amorphous materials are borne out by the volume of work on the kinetics of the process. Various direct, as well as indirect, means have been employed to follow the process of crystallization. Investigation of the process in amorphous fibres by direct observation by TEM or x-ray diffraction is extremely difficult due to the very small radial dimensions, and researchers must resort to indirect means like resistivity measurements. Whereas the earlier work was on post-crystallization changes, this work focused on samples annealed at near and below crystallization temperatures. In the former, the electrochemical response as well as resistivity changes were influenced not only by the phase fraction of the primary [alpha]-Fe phase, but also by the appearance of secondary phases like Fe[sub 2]B, Fe[sub 3]B, etc., as well as by themore » process of grain growth of each phase. In this work the annealing temperatures and times were selected such that the contribution of secondary phases could be precluded and thus the process of crystallization of the primary phase could be studied. Although the emphasis was on electrochemical measurements as a means of studying the crystallization process in Fe[sub 77.5]Si[sub 7.5]B[sub 15] amorphous fibres, the authors also obtained isothermal resistivity values as alternate measures of the crystallization process. In this paper they have tried to explain the differences observed in the two measurement techniques.« less