Search

The paper will present an analysis of kinematics of coupled circulatory gears with cylindrical and bevel wheels with the use of contour graphs method. This method has already been used to analyze the kinematics of lever mechanisms and toothed planetary gears and planetary gears coupled with cylindrical wheels. A formula for kinematic gearing was also derived using Willis' formula, thanks to which it is possible to verify the metadata of contour graphs.

People are pursuing high-efficient production and high quality of life. However, the dark and damp problem of the dark side of the house has not been solved well. In order to allow the residents to enjoy the sunshine of nature and make the building more energy-efficient and natural, this paper proposes a heliostat for daylighting. It operates based on a 2:1 transmission ratio mechanism integrated with a sun-position sensor. And this specific structure simplifies the control method since it works well as long as the sensor is just directed at the sun. A geometrical model of the heliostat concerning installation errors was built. And the heliostat’s performance was analysis by the simulation. The feasibility of the heliostat was verified.

Gear system is characterized by high efficiency, compact structure, and transmission ratio stability, and it has been extensively applied in various industrial equipment. This paper presents a novel preliminary estimate method for gear reducer noise radiation and vibration characteristics, and systematic researches on radiation characteristics of gear reducer are made. In the noise analysis process, the influence of time-varying mesh stiffness, error excitation, and tooth flank contact feature are comprehensively considered, the linear vibration model and nonlinear vibro-impact model for transmission system is set up, and then the dynamic load of the gearbox is obtained by solving the model. The dynamic load of bearing is taken as an excitation, the finite element method/boundary element method is adopted to analyze vibration and noise radiation characteristics of the gear reducer. The time domain response and field point noise spectrum at sound field are obtained, and the influence of harmonic components in excitation on vibration noise radiation of gearbox are discussed. The dynamic characteristics and sound radiation characteristics of gear reducer under different operating conditions are calculated, the change pattern of frequency component of the bearing dynamic load and noise radiation based on operating condition are obtained, and some interesting conclusions are observed from research that the gearbox produce the linear vibration and noise under the heavy load condition. Meanwhile, the nonlinear vibro-impact and noise is appeared under light load condition. The distribution of the gearbox radiated nose is uniform in various conditions, but noise takes sub-harmonic components as fundamental frequency and more peaks in the noise spectrum are observed. With the increase of the rotary speed, the noise tallies with the trend described by Kato formula except that under the gear system resonance speed. The impact force between teeth flanks shall be on the increase with the increase of rotary speed, and gear pair vibration experiencing a course from irregular vibration to regular periodic rattle vibration. With the increase of load, the noise of reducer changes with load as the variation of logarithmic function. For the noise in the process with load on the increase from no-load (the load is 0), the gear reducer vibration condition experienced both sides collision, single-side collision, and normal meshing in three stages. The radiated nose is increased gradually, but the abrupt change happened in critical positions between both sides collision and single-side collision as well as single-side collision and normal meshing in the process. The conclusions of this paper will offer theoretical basis for reducer to reduce vibration and noise.

With the rapid development of our country's economy, the number of motor vehicles has continued to grow rapidly, and the safety of driving has become an important issue[1]. The lack of vision and vision of the driver will directly affect the safety of driving. The transmittance meter is used to measure the visible light transmission ratio of the glass in the driver's view area. It is great important whether the indication is accurate or not. In this paper, the standard neutral filter is chosen as the standard, and the uncertainty of the measurement error of transmittance meter is evaluated and discussed.

For a vehicle, its speed can be adjusted via a transmission system. In this study, we propose a model of two-class rotation transmission nanosystem to adjust the input rotation via a gigahertz rotary nanomotor. To obtain an efficient rotation transmission system, carbon nanotubes, which have super-high in-shell strength but extremely low inter-shell friction, are adopted to build the coaxially rotary components. Besides 200 GHz motor, the other two components are the rotor1 in the class-1 nanobearing, and the rotor2 in the class-2 bearing, respectively. Considering both the chirality and radii differences of the rotary components, 27 types of transmission models are built and tested via molecular dynamic simulations. When the transmission ratio of the rotational frequency of the rotor2 and the input frequency is between 0.1 and 0.9, a successful transmission system is obtained. According to the rotation transmission ratios (RTRs) of both rotors in each model, some conclusions are drawn for potential design of such nanodevice. Besides, temperature can also influence the output rotation of the rotor2. It implies another way to adjust the output rotation from the same transmission system.

The results of analysis of the frequencies of t-alleles and heterozygous +/t individuals of house mice of different subspecies (musculus, bactrianus, tataricus, wagneri, and gansuensis) are presented for the natural populations inhabiting eight cities and five regions of Russia and adjacent countries of Eastern Europe and Asia. It is shown that the frequencies of t-alleles are 0.18 ± 0.03 in small samples (1–30 individuals) and 0.09 ± 0.06 in medium-sized samples (31–60 individuals). The factors that reduce the frequencies of t-alleles in natural populations and the mechanisms that prevent invasion and fixation of t-mutant alleles in the Mus musculus genome are discussed.

The objective of this study is to investigate the dynamic characteristics and optimize the required power of an electric bicycle equipped with a semi-automatic transmission. In this simulation, we analyze the dynamic characteristics and operating characteristics of an electric bicycle at each gear ratio based on the effects of input parameters such as gear-speed, frontal area, and slope grade by using Matlab-Simulink. Through this simulation, an analysis is conducted to maximize the power generation of the electric bicycle. The simulation results show that the required power can be optimized by changing the key parameters mentioned above. In addition, a model-based control study is conducted to control the bicycle speed under the effects of gear-speed and slope grade. We also conduct an experiment on a real road and analyze the dynamics and required power of the electric bicycle. The experimental results agree well with the simulation results at each transmission ratio. This combination of simulations and experiments provides a useful method to estimate the power requirements for the motor of an electric bicycle.

In today's mechanical transmissions most widely used, the gears, are spread across all industries. For this reason, their importance has become overwhelming, which is why we want to recall in this paper some important aspects regarding toothed wheels. It is the geometry, cinematic, the forces and the yields of these mechanisms, which will be presented in the work in the form of newly synthesized relations on modern bases. Another important aspect in toothed wheels is their synthesis by modern methods that avoid tooth interference during operation. To avoid the interference between teeth, we must know the minimum number of teeth of the driving wheel, in function of the pressure angle (normal on the pitch circle, alpha0), in function of the tooth inclination angle (beta) and in function of the transmission ratio (i). In optimal and high-efficiency gearing, gears require a modern design with increased coverage. These achievements can only be achieved today in the context of lowering the value of the alpha engagement angle. Through all the aspects presented, which relate to the dynamics of gears, the work can be considered among those of the optimal dynamic synthesis of the gears.

An overview of all possible structural schemes of two-carrier planetary gear trains (PGTs) with two compound and four external shafts is made. One of possible application of these PGTs is as change-gears. A few cases of this application are presented and investigated through the torque method. Kinematical possibilities of PGTs in question as function of parameters of component simple PGTs are discussed.

The simple planetary mechanism is geometrically synthesized by determining the four tooth numbers of the component wheels. There are four main conditions that if not obeyed the mechanism will be blocked, will work with interruptions, or will not work at all. (a) The first condition in the geometric-kinematic synthesis of a simple planetary is the uniform loading of satellites (satellite groups) (or the simultaneous engagement condition). (b) The coaxiality condition is the second one to be observed, otherwise, the mechanism is inoperative. (c) The condition for achieving a required input-output transmission ratio is the third major condition, which results from the necessity of conceiving the mechanism according to the required operation. (d) The fourth imposed condition is that of (good) neighboring (of the satellite groups), which is necessary for the larger satellites belonging to two groups of neighboring satellites not to be touched, which is why it is necessary to introduce the additional condition, neighborhood.

The accuracy of high performance electromechanical actuator(EMA) system model has important influence on the simulation accuracy of aircraft guidance and control loop. Aiming at solving the deficiency in the reflection of EMA characteristics using traditional second-order model, a high-fidelity global coupling modular structure modeling method is proposed. Based on the analysis of the modeling process, high-fidelity modeling research is conducted on "BLDCM/ball screw/fork" type EMA systems. The structure of high fidelity model is investigated, and modeling methods of nonlinear factors such as servo motor, transmission ratio, mechanical inertia and transmission flexibility in the system are examined in detail. Simulation results based on simulink platform show that the high fidelity model established by this method is highly consistent with the actual system performance of the input-output characteristics and the internal state characteristics, ensuring the authenticity of the system model, which plays an important effect on improving the simulation accuracy of the aircraft guidance and control loop.

Noncircular gears can be applied to realize non-uniform transmission ratio for various mechanical systems. However, due to the complex geometry, the manufacture and measurement constitute great hindrance to the application. Recently, a practical shaping method has been applied to the manufacture of noncircular gear. Yet along with this, still no investigation has been conducted into the measurement method or device for noncircular gears. In this regard, the paper aims for a quick measurement of shaped noncircular gears. The manufacture of noncircular gears is discussed first, a mathematical model for non-uniform flank rolling measurement is established then, and finally, the measurement processing is introduced, including the developed measurement device, the computerized measurement system and a measurement experiment.

This study aimed at investigating two original topics on self-healing concrete, 1) the prediction of long-term healing progress and 2) the evaluation of re-healing performance for a previously healed but reopened crack, using the air-coupled surface-wave method. Small-scale plate concrete specimens were fabricated with a self-healing binder incorporating ground granulated blast furnace slag, Na2SO4, anhydrite, and graded clinkers. A single flexural crack of 0.25–0.30 mm width was generated near the mid-span of each specimen. Then, the specimens were kept immersed in water, and the healing progress of the cracks was monitored for approximately one year. As a result, the residual surface crack area was reduced to 15.1% of the fully-cracked condition, and the surface wave transmission ratio recovered up to 82.9% of the uncracked condition. A prediction model for the ultimate healing rate and initial healing rate was proposed based on surface-wave results. After the first self-healing process, the specimens were loaded again, and a similar crack was produced at the previously healed zone in each specimen. Then, the re-healing performance was evaluated for about two months. From the second self-healing process, one specimen with a narrow reopened crack showed a satisfactory recovery in surface wave transmission, comparable to that in the first healing.

A free-running model of a truck train, which simulates a truck train consisting of a tow truck MAN TGS 19.360 and a biaxial semitrailer Utility VS2DС with a steerable front axis, has been developed. A semitrailer model is active with the wheel drive enables to control its movement by slow downing one of the wheels. The model was equipped with all necessary control equipment. It proved that driving a semitrailer by slow downing one of its wheels is identical to driving a semitrailer front axis with direct drive and a driver transmission ratio of 0.5. Differences in all cases have not exceeded 12% that is slowingdown one of the wheels of a semitrailer is reasonable for driving a truck train with a long base semitrailer.

The presence of mutually counteractive load torques in the so-called coupling gear set that is included in some configurations of planetary gearing for the purpose of achieving a high transmission ratio represents a problem in gearing design. The thus formed power-recirculating gearing will conceal two sources of relatively high frictional power loss by virtue of the presence of relatively high speeds as well.

Planetary gearbox could provide considerable transmission ratio in a small casing. Usually, planetary stage works under heavy loads. Gears inside planetary gearbox may suffer from damages including pitting, spalling and tooth broken. Sun gear fault diagnosis is a challenge since sun gear is in the center of the planetary gearbox. To address fault diagnosis of sun gear, a method named continuous vibration separation is presented in this paper. The method is compared with MED, which is a impulsive signal enhancement method. Fault seeded experiment is conducted to validate the method. Signal analysis result indicates that a combination of CVS and MED is more effective.

International audience; Many buildings may suffer damage due to ground movements associated to underground excavations like tunneling, mines or urban excavations. The level of damage depends upon the rate of ground movements transmitted to structures that is affected by the soil-structure interaction (SSI) conditions and parameters such as the soil elastoplastic behavior. The purpose of this paper is to integrate the soil elastoplasticity while investigating the response of a structure sitting on a soil subjected to a ground movement. Analytical and numerical approaches are applied to examine the effect of the non-linear soil behavior. The analytical approach is based on modified Winkler and Pasternak elastic models under the assumption of limiting the soil reaction by its bearing capacity; the numerical approach is based on finite element models, using Plaxis 2D that consider an elastoplastic soil behavior. Results display the discrepancy in the structural response between considering an elastic or an elastoplastic soil behavior. Based on a significant number of iterations, the artificial neural network technique is used to propose a new simplified meta-model that integrates the soil elastoplasticity to evaluate the transmission of ground movements to structures. In addition, a procedure, which can be used by engineers and designers, is developed to evaluate the transmission ratio for any structure sitting on any type of soil.

Ovim radom projektiran je dvostupanjski koaksijalni prijenosnik snage. Uz zadane osnovne parametre napravljen je proračun i kontrolni proračun zupčanika prvog i drugog sprega. Na drugom spregu se nalaze kosi zubi kod zupčanika, a na prvom spregu ravni zubi zupčanika. Odabrano je ulje za podmazivanje gdje je izračunata obodna brzina diobenog kruga i tangencijalne sile na zupčastim parovima koje utječu na viskoznost ulja. Zupčanici su smješteni na ukupno tri vratila, ulazno, međuvratilo i izlazno kod kojih je bilo potrebno izračunati sigurnosti u kritičnim presjecima. Reduktor je prema samom proračunu predimenzioniran te je optimizacija reduktora izvršena u programu KISSsoft., In this final paper we designed a two-stage coaxial power transmission. With the given basic parameters, a calculation and a control calculation of the first and second coupling gears were made. The second coupling gear has angled teeth, and the first coupling gear has straight teeth. Lubricating oil was selected where the circumferential speed of the camshaft and the tangential forces on a pair of gears affecting the viscosity of the oil were calculated. The gears were located on a total of three shafts, an input, intermediate shaft and an output shaft where it was necessary to calculate safety in critical sections. The gearbox was oversized according to the calculation itself, and the gearbox was optimized in KISSsoft.

In this chapter, the main types of gearing used in practical applications for transferring power between parallel, intersecting and crossed axes are described. The tooth parts and some quantities that characterize the toothing are also described and defined. The first law of gearing to be met to have a constant transmission ratio is also recalled, and the main geometric and kinematic parameters of gear drives, gear pairs, and gear wheels are defined. The geometrical parameters concerning the toothing and its sizing are expressed in terms of transverse module, but indications are given to express them in terms of transverse diametrical pitch. Moreover, the ranges of the reference values of efficiency obtainable with the various types of gears are provided, with indications for reaching the maximum values. Finally, attention is focused on the parameters that define the precision of the teeth and the accuracy grade of the gears, highlighting their influence on the transmission error, under static and dynamic conditions.

Razvojem tehnologije povećavaju se zahtjevi na strojeve, a samim time i na prijenosnike snage i gibanja. Razvoj novih strojeva od konstruktora zahtjeva da razvije proizvod sa što većom preciznošću uz što manju dimenziju. Kako bi se takvi strojevi mogli razviti, potrebni su posebni dijelovi. Jedan od takvih dijelova je upravo harmonijski prijenosnik koji će se obraditi u ovom tekstu. U malim dimenzijama osigurava veliki prijenosni omjer te svojom konstrukcijskom izvedbom poništava zračnost među zubima i na taj način osigurava veliku preciznost prijenosa. Svi proračuni provedeni su u programskom paketu SMath, analiza metodom konačnih elemenata provedena je u programskom paketu Abaqus, dok je prilikom konstrukcijske razrade korišten programski paket SolidWorks. With the development of technology, the demands on machines are increasing, and therefore demands on power and motion gearboxes are increasing too. The development of new machines requires from product designer to develop precise product with the smallest dimensions possible. To develop such machines, special parts are needed. One such part is the harmonic drive that will be elaborated in this text. In small dimensions harmonic drive can provide large transmission ratio and its construction design eliminates the tooth backlash, thus ensuring high transmission accuracy. All calculations were carried out in the SMath software package, finite element analysis was carried out in the Abaqus software package, while the Solidworks software package was used during the construction phase.

Summary The mouse sex chromosomes exhibit an extraordinary level of copy number amplification of postmeiotically expressed genes [1, 2], driven by an “arms race” (genomic conflict) between the X and Y chromosomes over the control of offspring sex ratio. The sex-linked ampliconic transcriptional regulators Slx and Sly [3, 4, 5, 6, 7] have opposing effects on global transcription levels of the sex chromosomes in haploid spermatids via regulation of postmeiotic sex chromatin (PMSC) [8, 9, 10, 11] and opposing effects on offspring sex ratio. Partial deletions of the Y chromosome (Yq) that reduce Sly copy number lead to global overexpression of sex-linked genes in spermatids and either a distorted sex ratio in favor of females (smaller deletions) or sterility (larger deletions) [12, 13, 14, 15, 16]. Despite a large body of work studying the role of the sex chromosomes in regulating spermatogenesis (recent reviews [17, 18, 19, 20]), most studies do not address differential fertility effects on X- and Y-bearing cells. Hence, in this study, we concentrate on identifying physiological differences between X- and Y-bearing sperm from Yq-deleted males that affect their relative fertilizing ability and consequently lead to sex ratio skewing. We show that X- and Y-bearing sperm in these males have differential motility and morphology but are equally able to penetrate the cumulus and fertilize the egg once at the site of fertilization. The altered motility is thus deduced to be the proximate cause of the skew. This represents the first demonstration of a specific difference in sperm function associated with sex ratio skewing., Highlights • The sex ratio skew in the offspring of Yq-deleted male mice is abolished by IVF • In Yqdel males, Y sperm are more severely morphologically distorted than X sperm • Similarly, Y sperm in these males have relatively impaired motility • This motility difference explains the sex ratio skew in offspring of these males, Mouse sex chromosome evolution has been shaped by widespread gene amplification, due to genomic conflict over offspring sex ratio. Rathje et al. show that male mice with a partial Y chromosome deletion show impaired morphology and motility of Y- versus X-bearing sperm, revealing the physiological basis of the sex ratio drive underpinning the conflict.

According to the characteristics of the large transmission ratio of the helicopter main reducer in the future, the research on the characteristic distribution of the planetary gear train of the helicopter main reducer is carried out. Because of the characteristics that the heavy load condition in helicopter main reducer’s running and the changeable running state and complex and harsh climatic conditions and the increasing heat of the flow field in the reducer, by the way, the large transmission ratio increases the uncertainty of the planetary gear train operation analysis at the same time, the probability of causing a failure is greater; Especially the complex and variable structure of the helicopter which has large transmission ratio main reducer makes the analysis difficulty further. For ensuring the safety and enhancing the reliability of the helicopter, this paper make a comparative analysis of the time domain characteristics of the state signals under the multi-operating condition between the normal planetary gear and planetary gears with different degrees of failure, to explore the distribution regularity of the fault characteristics of the helicopter main reducer, so as to realize the research on fault diagnosis of helicopter large transmission ratio planetary gear.

A gear effect is demonstrated at parallel and cross junctions between boron nitride nanotubes (BNNTs) via atomistic simulations. The atoms of neighboring BNNTs are meshed together at the junctions like gear teeth through long-range non-covalent interaction, which are shown to be able to transmit motion and power. The sliding motion of a BNNT can be spontaneously translated to rotating motion of an adjoining one or viceversa at a well-defined speed ratio. The transmittable motion and force strongly depend on the helical lattice structure of BNNTs represented by a chiral angle. The motion transmission efficiency of the parallel junctions increases up to a maximum for certain BNNTs depending on displacement rates. It then decreases with increasing chiral angles. For cross junctions, the angular motion transmission ratio increases with decreasing chiral angles of the driven BNNTs, while the translational one exhibits the opposite trend.

The rule of Mendelian inheritance is remarkably robust, but deviations from the equal transmission of alternative alleles at a locus [a.k.a. transmission ratio distortion (TRD)] are also commonly observed in genetic mapping populations. Such TRD reveals locus-specific selection acting at some point between the diploid heterozygous parents and progeny genotyping and therefore can provide novel insight into otherwise-hidden genetic and evolutionary processes. Most of the classic selfish genetic elements were discovered through their biasing of transmission, but many unselfish evolutionary and developmental processes can also generate TRD. In this review, we describe methodologies for detecting TRD in mapping populations, detail the arenas and genetic interactions that shape TRD during plant and animal reproduction, and summarize patterns of TRD from across the genetic mapping literature. Finally, we point to new experimental approaches that can accelerate both detection of TRD and characterization of the underlying genetic mechanisms.

On the basis of the patents of one of the authors, constructions of a range of multi roller cyclo reducing gear have been developed, having the advantage of achieving a high gear ratio of one stage. The main element of the cyclic gearbox is a generator delivering a translational movement created by input eccentric shaft rollers. The transmission of the torque from the generator is accomplished by engaging a large number of rollers in a ring gear to redistribute the load of the cyclo reducing gear. It is compact, with small dimensions. In the elaboration, dependencies are derived for determination of the transmission ratio and the geometric dimensions of the elements of the cyclo reducing gear.

The operation effectiveness of multi-bar transplanting mechanisms is low, and the specific changing law of the transmission ratio (the curve of the transmission ratio has twice unequal amplitude [TUA] fluctuation.), which is needed in vegetable pot seedling transplanting, is difficult to fulfill using a planetary gear train with noncircular gears and a single-planet carrier. To address this problem, we propose a noncircular gear pair that comprises an incomplete noncircular gear, rack, partial noncircular gear, and elliptical gear. The structural characteristics and the working principle of the TUA gear pair were analyzed. The pitch curve equation of the noncircular TUA gears was derived from the relationship of the angular displacement of the corresponding pitch curves. The influence of central angle α and eccentricity k on the shape of the pitch curve, angular displacement, and transmission ratio of the TUA gear pair was analyzed. The TUA gear pair was applied to a proposed vegetable seedling pickup mechanism (SPM) considering the design requirements. Finally, the feasibility of the new noncircular TUA gear transmission mechanism was verified by an SPM test.

In this paper, the low frequency random load of a tractor is presented. Controlled by a theoretical three-parameter shift schedule, the random load would frequently trigger the random shift. Simultaneously, the driving force of the tractor should be consistent prior to and following this shift. Additionally, the higher traction efficiency and improved load utilization rate should be ensured by a choice of a transmission ratio of the tractor power shift transmission. The shift schedule was utilized for the aforementioned problems solution. An innovative method is presented for theoretical shift schedule modification by the fuzzy algorithm, based on the random load standard deviation and the alteration rate of both steady state values of the load and of the throttle position. The simulation results demonstrated that the modified shift schedule could discover the running state of the tractor. By shielding the random shift judgment caused by the random load, the stability of the tractor was ensured. When the shift was required, the schedule could rapidly respond, whereas the tractor driving force did not sustain a sudden alteration. The schedule could also automatically select and maintain the transmission ratio with higher traction efficiency.

This is an article translated from the original version published in the Journal of the Society of Powder Technology, Japan. A new method for evaluating powder flowability is developed using a constant-volume shear tester; this tester measures the upper and lower normal stresses and the shear stress acting on a powder bed. A single shear test provides a series of characteristics, such as the powder yield locus (PYL), consolidation yield locus (CYL), critical state line (CSL), shear cohesion, stress relaxation ratio, stress transmission ratio, and void fraction. The values of shear stress as a function of the normal stress and void fraction are visualized in three-dimensional diagrams. Furthermore, powder flowability is evaluated using a flow function obtained from the PYL.

The paper presents the kinematic analysis of the double harmonic gear transmission by comparative determining of the transmission ratio for two constructive variants of these transmissions. It demonstrates the viability of double harmonic gear transmission (DHGT) by presenting the operating principle and calculation of transmission ratio by using the analytical method of inversion motion. We performed a comparative analysis of transmission ratio for the two kinematic models of DHGT (z2 = z'2, respectively z2 ≠ z'2).