Transmission Errors Research Articles

Heart to Heart

A comprehensive comparison of the Chinese and Sanskrit texts of the Heart Sutra shows that, even after correcting transmission errors, there are substantial differences between them. Most of the differences appear to arise from the process of translating the text from Chinese to Sanskrit in isolation from Sanskrit Prajñaparamita literary traditions. Some differences appear to reflect the differing doctrinal commitments of those involved in creating/transmitting the texts. Following a suggestion by Huifeng (2014), I take a phenomenological approach when reading the Heart Sutra, effectively creating a new kind of commentary that eschews the usual references to metaphysics, mysticism, and magic. The focus here is on the phenomenology of sensory experience and especially the cessation of sensory experience in meditation.

Engineering design and testing of rotary joints’ driving systems for the CFETR multi-purpose overload robot

This study focuses on the engineering design and testing of the rotary joints' driving systems for the China Fusion Engineering Test Reactor (CFETR) Multi-Purpose Overload Robot (CMOR). CMOR is a critical component in the CFETR. The CFETR tokamak serves as an engineering test reactor in China for magnet confinement fusion research. CMOR, a 7-DOF manipulator, is specifically designed for internal maintenance within the CFETR. This poses significant challenges in the design of the joint driving systems. The joint types of CMOR are categorized into three, comprising one translation joint, two swing joints, and four rotary joints. Using rotary joint J6 of CMOR as an example, this paper provides a detailed exploration of the engineering design and testing of the rotary joints' driving systems, offering a comprehensive explanation of their design specifications and principles. Specification and strength assessments are conducted on the engineering design results, meeting all requirements. Furthermore, the paper delves into the testing methods of the driving systems, including the assessment of transmission error and backlash error, two crucial indicators for the driving system. This research contributes valuable insights for future joint designs and testing of the CMOR heavy-load manipulator.

REDUCING THE KINEMATIC ERROR OF AN ECCENTRIC TRANSMISSION
 WITH A PARALLEL LOCATION OF INPUT AND OUTPUT SHAFT
 AS A RESULT OF THE APPLICATION OF A DOUBLE-FLOW LOADING SCHEME

The article presents kinematic diagrams and computer analysis of three types of eccentric transmission schemes.
 The graphical dependences of the kinematic error of the eccentric transmission are presented for the coaxial and
 parallel arrangement of the input and output shafts in two single-flow loading schemes. Computer analysis of an
 eccentric transmission with single-flow loading schemes showed that the kinematic error with the coaxial arrangement
 of the input and output shafts is 30 times lower than with the parallel arrangement of these shafts. In order to reduce
 the kinematic error of an eccentric transmission with a parallel arrangement of input and output shafts, a two-flow
 loading scheme was proposed. It has been established that the use of a double-flow loading scheme makes it possible
 to reduce the kinematic error by 12 times compared to a single-flow loading scheme with a load on the output shaft
 of 10 N∙m.
 It is planned to use the design of an eccentric transmission with a parallel arrangement of input and output
 shafts with several power flows when designing various types of gearboxes for cultivators.

Dynamic Event-Triggered Intermittent Fault Detection for Time-Varying Stochastic Systems

In this paper, the problem of intermittent fault (IF) detection is investigated for stochastic linear time-varying (LTV) systems using dynamic event-triggered methods. Using the nonuniform sampling approach, the event-triggered system is transformed into a time-varying system with varying sampling periods. Using the moving horizon estimation strategy, a new IF detection filter is designed to generate residual signals which are decoupled from event-triggered transmission errors and estimation errors. Moreover, an event-triggered IF detection algorithm is proposed such that the appearance time and disappearance time of IFs can be detected quickly for stochastic LTV systems. In order to analyze the detectability of IFs for systems with/without event-triggered cases, the concept of distinguishability is introduced for IFs. Sufficient conditions are derived to guarantee the detectability of IFs for LTV systems. Finally, an experiment concerning the rotary steerable drilling tool system is provided to illustrate the effectiveness of the proposed IF detection method.

Research on the UOSM four-port Calibration algorithm and determination method of the Transmission error term

As one of the key techniques for vector network analyzers to achieve high precision measurement, calibration, and error correction technology has always been the focus of continuous exploration and innovation. UOSM calibration algorithm uses unknown straight-through transmission standards that do not need to be defined and known open-circuit standards, short-circuit standards, and matching standards to calibrate microwave and millimeter wave bands. Based on the study of the mature UOSM calibration algorithm, this paper proposes a method of self-calibration and comparison of the measurement data based on the unknown cut-through standard, which no longer needs the group delay parameters of the unknown straight-through standard and reduces the dependence on the calibrator. The accuracy of the algorithm and error item determination method is verified by ADS simulation and instrument actual test, and a good calibration effect is achieved. It is proved that the algorithm has the ability of accurate calibration. Due to the reduction of parameters, the stability and applicability of the algorithm are improved.

Dynamic characteristics analysis of gear tooth modification in a three-stage gear system

Gears serve as vital elements in high-efficiency mechanical transmissions, playing a pivotal role in vehicles. Employing gear modification has the capacity to significantly enhance the dynamic properties of the Planetary Gear Transmission (PGT) systems. In this study, the investigation has been directed toward a three-stage PGT model system with a comprehensive consideration of various vibration-related factors that affect the dynamic behavior of the system. These factors are encompassed by Time Varying Mesh Stiffness (TVMS), torsion and bending forces experienced by connecting shafts, dynamic Transmission Error (TE), impact of gear meshing eccentric load forces, inherent flexibility in the supporting shaft structure, and influence of torque and power fluctuations originating from a multi-cylinder engine. The estimation of TVMS is carried out for both external-external and external-internal teeth meshing pairs, utilizing the Potential Energy Method (PEM). Subsequently, this study employs the lumped parameter method to establish a model with a specific objective of investigating the lateral-torsional-coupling behavior within adopted PGT model system. The lateral vibration displacement characteristics of the PGT model system is deeply analyzed, revealing the influence of speed on lateral vibration and displacement frequency domain characteristics through a 3D waterfall diagram. Furthermore, a Tooth Profile Modification (TPM) method is applied utilizing two distinct parameters namely [Formula: see text] TPM parameter and [Formula: see text] TPM parameter. The objective is to mitigate vibrations and evaluate the performance of the adopted PGT model after employing each TPM parameter through both TVMS and Root Mean Square (RMS).

Development of the method of detecting and correcting data transmission errors in IoT systems for monitoring the state of objects

The object of the study is the IOT system for monitoring the state of objects. The problem being solved is the development of an innovative method of detecting and correcting data transmission errors in the networks of Internet of Things systems. The essence of the results is that a method of detecting and correcting multiple transmission errors during byte-by-byte transmission of a block of information has been developed. The method is distinguished by an original coding scheme, which involves the calculation of control bits, as well as the shuffling of block bits by performing bit shift operations. The peculiarity of the method is that any bit can be distorted when transmitting a code word, but it belongs to different code combinations of the Hamming code. This allows multiple data transmission errors to be detected and corrected during decoding, and multiple errors of different bytes belonging to the same block can be corrected. Simple algorithms for encoding and decoding procedures have been developed, and programs for information block encoding procedures and decoding procedures with error detection and correction have been developed. A software model of the data transmission channel was also developed with the possibility of introducing multiple errors when simulating the data transmission process. All programs are developed in Python, although other languages are possible. An experiment was conducted using the developed software model of the data transmission channel. The efficiency of the developed method has been experimentally confirmed and it has been proven that its use increases the immunity of the data transmission channel. This is due to the fact that the developed method allows detecting and correcting all code word transmission errors with a multiplicity from 1 to 8, which was confirmed experimentally. The main field of use of the developed method is considered to be IoT system networks. First of all, systems for monitoring the state of objects

Meshing equation, tooth contact analysis, stress analysis and manufacture of a point-contact gear formed by double-arc milling cutter

The processing and design of point-contact gears have attracted the interest of many scholars. The point-contact gears are usually processed by specialized machines (face-milling and face-hobbing) or five-axes machines (forming milling). In this paper, a new type of point-contact gear formed by double-arc milling cutter on four-axes machine is proposed. Firstly, the meshing equation is proposed to obtain a pair of processing traces that satisfy the law of gearing, and the processing traces are also contact traces. Considering the important role of traces in obtaining the proposed gear, this gear is called as TG. Then, six pairs of contact traces for parallel-axes, crossing-axes, and skewing-axes TGs are solved. Furthermore, the tooth surface models are studied and the obtained models are used for tooth contact analysis and stress analysis, and then the instantaneous contact areas, the contact stresses, and transmission errors are obtained, respectively. Lastly, the TG pair with cross-axes is processed, and then, the measurement and rolling experiments are conducted. The obtained results indicate the meshing equation, tooth surface models, and milling method are feasible. The proposed milling method provides a new way for flexible and diversified manufacturing of point-contact gears.

Geometric contact characteristics of variable hyperbolic circular-arc-tooth-trace cylindrical gear under different machine tool errors and sensitivity analysis for impact factors

Machine tool error is one of the most important research contents in gear transmission error, and contact characteristics are important factors affecting gear transmission performance. The establishment of tooth contact analysis (TCA) model of gear pair plays a guiding role in analyzing contact characteristics of gear pair. Based on the forming principle of variable hyperbolic circular-arc-tooth-trace cylindrical gear (VH-CATT gear), the structure model and coordinate system of VH-CATT gear machine tool are established. Based on the gear meshing conditions, the tooth surface mathematical model of the VH-CATT gear with machine tool error are established, and the TCA model with machine tool error is established. The influence of different machine tool errors on the geometric contact characteristics of the gear pair is analyzed. The results show that the pressure angle error, rotation error in y direction, and rotation error in z direction, translation error in y direction, and rotation error in z direction have a significant impact on the contact characteristics of tooth profile of VH-CATT gear.

Equalizer Parameters’ Adjustment Based on an Oversampled Channel Model for OFDM Modulation Systems

A physical model of a wireless transmission channel in the time domain usually consists of the main propagation path and only a few reflections. The reasonable assumptions made about the channel model can improve its parameters’ estimation by a greedy OFDM (Orthogonal Frequency Division Multiplexing) equalizer. The equalizer works flawlessly if delays between propagation paths are in the sampling grid. Otherwise, the channel impulse response loses its compressible characteristic and the number of coefficients to find increases. It is possible to get back to the simple channel model by data oversampling. The paper describes how the above idea helps the OMP (Orthogonal Matching Pursuit) algorithm estimate channel coefficients. The authors analyze the oversampling algorithm on the one hand to assess the influence of filtering function and signal resolution on the quality of the channel impulse response reconstruction. On the other hand, the abilities of the OMP algorithm are analyzed to distinguish components of the oversampled signal. Based on these analyses, we proposed modifications to the compressible channel’s impulse response reconstruction algorithm to minimize the number of transmission errors. A distinction was made between the filters used in the OMP search and channel reconstruction stages before calculating equalizer coefficients. Additionally, the results of the search stage were considered as elements within the groups.

Electromechanical coupling dynamics of dual-motor electric drive system of hybrid electric vehicles

In this study, to investigate the electromechanically coupled dynamics of a dual-motor electric drive system (DEDS) of hybrid electric vehicles under typical conditions. Considering the time-varying stiffness of gears, a dynamic model of the gear system and permanent magnet synchronous motor (PMSM) was developed, and a comprehensive electromechanical coupling dynamics model of DEDS applicable to coupling dynamics analysis was obtained. Based on this model, the impacts of the transmission error and electromechanical coupling effect on the dynamics of DEDS under steady-state and acceleration conditions were simulated and analyzed. This study demonstrates the significant impact of transmission errors on the dynamic load of high-speed gear pairs and the speed synchronization characteristics of the system. The study also reveals that the electromechanical coupling effect exacerbated the fluctuation of the gear dynamic load. During the speed change process, the electromechanical coupling effect did not introduce new resonance points. However, transmission errors tend to induce low-frequency resonance of the gear dynamic load and speed synchronization error (SSE). In addition, when the system is operated near the resonant speed, a large torsional vibration dominated by the resonant excitation frequency is generated, distinguished using the current signal to assess the resonance risk. The research results are important for the integrated design and condition monitoring of DEDS and offer valuable insights for enhancing the operational efficiency and reliability of the system.

Study on nonlinear dynamic characteristics of a two-speed transmission system at low speed.

A pure shear mechanical model of low gear of six-degree-of-freedom two-speed transmission system is established by using lumped parameter method. The Runge-Kutta method is used to numerically solve the aforementioned nonlinear system. The variation of transmission error between gears is analyzed by using global bifurcation, time domain diagram, phase diagram and Poincare cross section. Moreover, the transfer error bifurcation characteristics of the solar wheel and the first planetary wheel under different gear moduli are investigated. The results show that: by taking the excitation frequency as the control parameter, the system includes period-1 motion, period-2 motion, quasi-periodic motion, multiperiodic motion, and chaotic motion. With the increase of gear modulus, the system mainly presents chaotic motion in the medium frequency range (0.5<ωh≤2). It shows stable period-1 motion in the high frequency range (2<ωh≤3), and the higher the modulus, the wider the high frequency range of period-1 motion. The research results can provide reference for the design and optimization of this kind of two-speed transmission system in the future.

Accuracy characteristics of the testing bench for dynamic transmission error

A high-precision testing bench is required for accurately assessing the dynamic Transmission error (TE) of precision reducers. However, the relationship between the testing bench’s accuracy and deviations in testing conditions has not been determined, leading to an inaccurate evaluation of its metrological performance. In this study, we examined the accuracy characteristics of the testing bench. We analyzed the structure of the bench and identified the main error sources that affect its accuracy, including mechanical system deviation, sensor measurement deviation, and testing condition deviation. In addition, we studied the mechanism of these error sources and proposed a method to convert drive speed deviation and load torque deviation into angle deviation by using a three-dimensional characterization model of lost motion. Based on the expression of TE, we proposed an evaluation method for the accuracy of the testing bench. Furthermore, we presented the methods for calculating the error sources and proposed a method for determining the TE of adjacent units based on the specific coupling structure. Finally, we conducted practical tests to validate the effectiveness of the proposed method in evaluating the accuracy characteristics of the testing bench. We found that the relative test error between quasi-static TE and dynamic TE is small, and more accurate test results are obtained when applying an appropriate load.

Improved analytical model for calculating mesh stiffness and transmission error of helical gears considering root curve: Theoretical analysis and experiments

A modified algorithm is proposed in this study to correct time-varying mesh stiffness (TVMS) and transmission error (TE) in helical gears considering tooth root transition curve. The parametric model of helical gear is established by using the meshing principle of helical gear and hob in order to obtain the accurate tooth root transition curve. Moreover, a TE test rig is set up to compare the theoretical and experimental results. The results of the improved algorithm are very similar to the experimental results compared to the traditional model, and the relative error of TE is also small. In this study, the effect of multi-parameters (e.g. pressure angle, meshing position, transverse contact ratio, and overlap ratio) on TE are investigated by comparing theory with experimental analysis. Through the analysis of parameters, it has been established that an elevation in pressure angle leads to a decrease in TE, followed by an increase. In the event that the meshing position is situated closer to the nodal point, the TE slightly decreases. Moreover, as the transverse contact ratio and overlap ratio increase, the TVMS increases, while the TE decreases. When the overlap ratio approaches an odd multiple of 0.5, the TE displays a significant peak.

Research on noise reduction of drive axle hypoid gear based on tooth surface mismatch modification

In order to reduce the transmission noise of drive axle hypoid gear, a method of tooth surface mismatch modification was proposed. Firstly, on the basis of establishing the grinding mathematical model of hypoid gear with cutter tilt, the theoretical tooth surface equation was derived, and the numerical tooth surface was calculated by dividing the grid points on tooth surface. Secondly, the pinion tooth surface which was full conjugated with gear tooth surface was constructed, and the tooth surface mismatch topography was established and decomposed into the first order and second order mismatch coefficients. According to the modification requirements, the pinion target surface was constructed by modifying the tooth surface mismatch coefficients, and the pinion modified machine setting parameters were acquired by establishing the pinion processing parameters corrected mathematical model. Finally, the loaded tooth contact analysis with finite element simulation and drive axle NVH (Noise, Vibration, Harshness) simulation were carried out for a pair of hypoid gear, therefore the loaded tooth contact areas, transmission errors curves, and noise simulation curves were obtained, and the simulation results show that after modification the tooth contact stress, loaded transmission errors amplitude, and NVH simulation curves value are all reduced. The road test results indicate that the drive axle hypoid gear howling phenomenon under the high speed operation can be eliminated, so the effectiveness of tooth surface modification method and NVH simulation method were verified.

Photonic MMW Generation Using PM-DPMZM for Full Duplex 32×10 Gbps RoF-WDM System

Abstract This paper presents a study of a 32×10 Gbps Radio over Fiber and Wavelength Division Multiplexing (RoF-WDM) full-duplex system that uses Phase Modulators and a Dual-Port Mach-Zehnder Modulator (PMs-DPMZM) for bidirectional data transfer. The system employs Millimeter-Wave (MMW) signaling over optical fiber and focuses on selecting a technology that provides high transmission capacity per wavelength, improved spectral efficiency, and resistance against optical transmission impairments. The proposed method was validated using simulation results to confirm the efficiency of the proposed system in generating a 40 GHz signal and efficiently detecting and modulating the RF signals. The results demonstrate that the system exhibits strong resistance against dispersion, non-linear effects, and noise, delivering satisfactory performance for distances of up to 220 km. By analyzing the input power, the paper establishes a relationship between input power and signal quality, revealing that an optimal power of 0 dBm leads to an improved Quality Factor (QF) and reduced transmission errors. Furthermore, the evaluation of received optical power indicates the power level required to maintain an acceptable error rate, approximately -20.9690 dBm for downstream data transfer and -20.7245 dBm for upstream data transfer at the BER limit. The simulation performance also demonstrates the transmission efficiency achieved through a high Polarization Mode Dispersion (PMD) coefficient of up to 0.8. The analytical calculations conducted in this work provide valuable insights for optimizing and enhancing the performance of RoF-WDM networks.

Multi-Objective Optimization Design of Cycloid-Pin Gears Based on RV Reducer Precision Transmission Performance

This paper aims to realize multi-objective optimization of cycloid-pin gears to improve the positioning accuracy and load-carrying capacity of the rotary vector (RV) reducer, via the consideration of backlash, transmission error, and torsional stiffness. Initially, the analytical models of the RV transmission backlash and transmission error are developed by using both purely geometrical and equivalent model methods individually. Based on the generalized Hooke’s law, a torsion angle model is established to characterize the torsional stiffness of the system, utilizing methods such as Hertzian contact theory and bearing stiffness models. Subsequently, employing the Monte Carlo method, extremum method, and quality loss function, mapping objective functions for dimensional accuracy (tolerance) and transmission performance (backlash, transmission error, and torsional stiffness) are constructed. The geometry dimensions, dimensional accuracy, and modification of the cycloid-pin gear are considered as design variables to create a multi-objective optimization model. The improved Parallel Adaptive Genetic Algorithm using Deferential Evolution (PAGA-DE) is used for multi-objective solutions. Through example calculations, the impact of cycloid-pin gear parameters on transmission performance before and after optimization is determined. The reliability of backlash after optimization within 1.5′ reaches 99.99%, showing an increase of 8.24%. The reliability of transmission error within 1′ reaches 98.52%, demonstrating an increase of 1.35%. The torsional angle is reduced by 8.9% before optimization. The results indicate that the proposed multi-objective optimization design method for cycloid-pin gears can achieve the goal of improving the transmission performance of the RV reducer.

A research study on methods for improving the service quality of a network system based on time information

The network delay is one of the important criteria for selecting computing and networking capabilities. Network delay is one of the important bases of computing network selection. With the continuous development and integration of digital technology, communication technology, and control theory, the research on control theory for networked systems has rapidly advanced. This study proposes an event-triggered mixed time-delay neural network (NN) synchronization method, aiming to reduce network transmission delays through the optimization of NNs, thereby enhancing service responsiveness or reducing errors in data transmission. Firstly, a discrete-driven NN model subject to mixed time delays is established, and the corresponding response network is constructed. In the design of the synchronization controller, a quadratic function is constructed based on the measurement of error states, serving as a threshold for designing the event-trigger mechanism. For the synchronization error system, by constructing a Lyapunov–Krasovskii functional dependent on time delays and a general µ-function, analytical techniques and matrix theory are applied to obtain sufficient criteria for the µ-stability. The validity of the theoretical findings is proven through numerical examples.

Positioning accuracy prediction of precision cycloid reducer based on a BDDTE model and use in design optimization

As users' expectations for precision cycloid reducer positioning accuracy rise, accurate positioning accuracy prediction of products before assembly and design solutions to improve product qualification rates are very important. Considering the actual manufacturing conditions of components, a new multi-source error (MSE) equivalence modeling assumption and pin gear's MSE measurement method are proposed, and the rationality of the assumption is verified through experiments. Based on the geometric characteristics of each component's MSEs, a new analytical model of bi-directional drive transmission error (BDDTE) is established, which organically unifies the prediction of transmission error (TE) and lost motion (LM). The influence of the output mechanism on the positioning accuracy of the entire reducer is found to be non-negligible through Monte Carlo simulation; meanwhile, the general tolerance allocation scheme makes it difficult to ensure that each prototype meets the performance requirements. For this reason, a new design solution for the positioning accuracy of the reducer with the pin gear and output mechanism as the optimization targets is proposed. Finally, the prototype test results show that the BDDTE model based on the new assumption has a higher accuracy in predicting positioning accuracy compared with the model based on the conventional assumptions. Meanwhile, the effectiveness of the proposed improvement design solution for positioning accuracy improvement is verified. The BDDTE model reveals the intrinsic connection between the TE and LM of the cycloid reducer, and the improvement solution has guiding effects on improving the product qualification rate.

Quasi-Static Force Analysis and Tooth Profile Modification Optimization of the Cycloid Speed Reducer

This article proposes a new method for optimizing tooth profile modification amounts of cycloidal reducers. By optimizing transmission error and transmission ratio fluctuation, the objective optimization function is determined, and the influence of optimized modification amount on various transmission performances is studied. In addition, this article also conducted mechanical analysis on the cycloidal reducer and obtained the results of tooth contact force. The mathematical model for the mechanical analysis of the cycloidal reducer was established, and the variation law of force distribution between the internal and external gears of the cycloidal reducer was calculated. The results indicate that the needle tooth force, bearing force, transmission ratio, and transmission error obtained through the mechanical analysis model using optimized modification quantities tend to stabilize and exhibit periodic changes, which corresponds to the actual scenario.