Study about anti-request design of transmission mechanism in job device of colliery sump cleaner

The paper takes reversal hexagon connecting bar mechanism which uses in colliery sump cleaner as research object, takes main performance of reversal hexagon connecting bar in loader as target and uses the idea of anti request project and modern design, raises a new method of engineering design. It has proved that the method is feasibility and correct by practice.

Overcoming the “reverse transmission mechanism” for sustainable growth

"Reverse transmission mechanism" is a deep-seated problem in China's economy.Understanding it is the key to unraveling the interaction among China's growth mechanism,cycles and policy options.In the new millennium,great changes have occurred in the economic environment and the "reverse transmission mechanism" has shown that it works in different ways.From this approach,this paper concludes that "welfare and administrative spending rigidity" after 2000 has a stronger feature of "reverse transmission," which forces China's economy onto a path of unsustainable expansion.To seek sustainable growth,new reverse transmissions of welfare and administrative spending must be broken.In light of the present phase of development,only by adjusting administrative costs and welfare spending can we balance development,transform the growth pattern,and embark on a sustainable path.

Design and characteristic research of a novel electromechanical-hydraulic hybrid actuator with two transmission mechanisms

Servo-hydraulic actuators(SHAs)are widely used in mechanical equipment to drive heavy-duty mechanisms.However,their energy efficiency is low,and their motion characteristics are inevitably affected by uncertain nonlinearities.Electromechanical actuators(EMAs)possess superior energy efficiency and motion characteristics.However,they cannot easily drive heavy-duty mechanisms because of weak bearing capacity.This study proposes and designs a novel electromechanical-hydraulic hybrid actuator(EMHA)that integrates the advantages of EMA and SHA.EMHA mainly features two transmission mechanisms.The piston of the hydraulic transmission mechanism and the ball screw pair of the electromechanical transmission mechanism are mechanically fixed together through screw bolts,realizing the integration of two types of transmission mechanisms.The control scheme of the electromechanical transmission mechanism is used for motion control,and the hydraulic transmission mechanism is used for power assistance.Then,the mathematical model,structure,and parameter design of the new EMHA are studied.Finally,the EMHA prototype and test platform are manufactured.The test results prove that the EMHA has good working characteristics and high energy efficiency.Compared with the valve-controlled hydraulic cylinder system,EMHA exhibits a velocity tracking error and energy consumption reduced by 49.7% and 54%,respectively,under the same working conditions.

Research on Interest Rate Transmission Mechanism of China’s Bond Market:Empirical Analysis Based on Granger Causality Complex Network

The bond market is an important market for investment and financing in China’s economic sectors,and also an important part of the monetary policy framework.The internal transmission of bond market is an important part of market interest rate transmission,which iscritical to the effectiveness of monetary policy.However,few scholars have studied the characteristics of interest rate transmission in China.An in-depth study of the interest rate transmission mechanism and its dynamic evolution between different bond markets is conducive to clarify the pulse of transmission within Chinese bond market and to further unblock the transmission mechanism of monetary policy.From the perspective of system theory and based on the analysis method of Granger causality complex network,this paper finds that the interest rate transmission among various varieties in China’s bond market is relatively significant.Treasury bonds and CDB bonds are the two core bond varieties of interest rate transmission in the bond market.Simultaneously,this study concludes that the medium and long-term interest rate played a dominant role in the transmission of market interest rate during the easing phase of monetary policy,while the short-term interest rate played a dominant role in the transmission of market interest rate during the tightening phase of monetary policy.This paper also gives enlightenment and suggestions.

The transmission mechanism theory of disease dynamics:Its aims,assumptions and limitations

Most of the progress in the development of single scale mathematical and computational models for the study of infectious disease dynamics which now span over a century is build on a body of knowledge that has been developed to address particular single scale descriptions of infectious disease dynamics based on understanding disease transmission process.Although this single scale understanding of infectious disease dynamics is now founded on a body of knowledge with a long history,dating back to over a century now,that knowledge has not yet been formalized into a scientific theory.In this article,we formalize this accumulated body of knowledge into a scientific theory called the transmission mechanism theory of disease dynamics which states that at every scale of organization of an infectious disease system,disease dynamics is determined by transmission as the main dynamic disease process.Therefore,the transmission mechanism theory of disease dynamics can be seen as formalizing knowledge that has been inherent in the study of infectious disease dynamics using single scale mathematical and computational models for over a century now.The objective of this article is to summarize this existing knowledge about single scale modelling of infectious dynamics by means of a scientific theory called the transmission mechanism theory of disease dynamics and highlight its aims,assumptions and limitations.

Finite-time non-fragile filtering for nonlinear networked control systems via a mixed time/event-triggered transmission mechanism

This paper is aimed at investigating the problem of mixed time/event-triggered finite-time non-fragile filtering for nonlinear networked control systems with delay.First,a fuzzy nonlinear networked control system model is established by interval type-2(IT2)Takagi-Sugeno(T-S)fuzzy model,the designed non-fragile filter resolves the filter parameter uncertainties and uses different membership functions from the IT2 T-S fuzzy model.Second,a novel mixed time/event-triggered transmission mechanism is proposed,which decreases the waste of network resources.Next,Bernoulli random variables are used to describe the cases of random switching mixed time/event-triggered transmission mechanism.Then,the error filtering system is designed by considering a Lyapunov function and a sufficient condition of finite-time boundedness.In addition,the existence conditions for the finite-time non-fragile filter are given by the linear matrix inequalities(LMIs).Finally,two simulation results are presented to prove the effectiveness of the obtained method.

A comparison of sensitivity indices for tolerance design of a transmission mechanism

Sensitivity analysis is used to quantify the contribution of the uncertainty of input variables to the uncertainty of systematic output responses.For tolerance design in manufacturing and assembly,sensitivity analysis is applied to help designers allocate tolerances optimally.However,different sensitivity indices derived from different sensitivity analysis methods will always lead to conflicting results.It is necessary to find a sensitivity index suitable for tolerance allocation to transmission mechanisms so that the sensitivity results can truly reflect the effects of tolerances on kinematic and dynamic performances.In this paper,a variety of sensitivity indices are investigated and compared based on hybrid simulation.Firstly,the hybrid simulation model of the crank-slider mechanism is established.Secondly,samples of the kinematic and dynamic responses of the mechanism with joint clearances and link length errors are obtained,and the surrogate model established using polynomial chaos expansion(PCE).Then,different sensitivity indices are calculated based on the PCE model and are further used to evaluate the effect of joint clearances and link length errors on the output response.Combined with the tolerance-cost function,the corresponding tolerance allocation schemes are obtained based on different sensitivity analysis results.Finally,the kinematic and dynamic responses of the mechanism adopting different tolerance allocation schemes are simulated,and the sensitivity index corresponding to the optimal response is determined as the most appropriate index.

Potential Risk of Transmission of Escherichia coli and Salmonella spp. Infections by the Musca domestica Fly and the Periplaneta americana Cockroach in the City of Cotonou (South Benin)

Background: The occurrence of bacterial infections sometimes involves synanthropic flies and cockroaches, as mechanical vectors of pathogenic microorganisms. The aim of this study was to identify the different species of flies and cockroaches that cohabit with humans in the city of Cotonou and determine the contribution of Musca domestica and Periplaneta americana in the transmission of bacteria responsible for infections in humans. Methods: Capture sessions during the day for flies and at night for cockroaches were carried out in 4 arrondissements of the city of Cotonou. The insects collected were transported to the Center of Research Entomological of Cotonou for identification, then sent to the Section Hygiene of Water and Food for microbiological analysis, enumeration and testing for human pathogenic bacteria. Results: A total of 351 flies and 26 cockroaches were collected at the sites, including two synanthropic species belonging to two families each. Musca domestica and Periplaneta americana were the most abundant species found after identification in the city of Cotonou. Thermo-tolerant coliforms and Escherichia coli were found on all specimens at varying concentrations. Salmonella spp. bacteria were identified in the fly population from the Dantokpa dump. Conclusion: Flies and cockroaches can transmit microorganisms to humans. The presence of Salmonella spp. among the specimens revealed that infections frequently caused by contaminated food or water are also transmitted to humans by flies. The presence of these germs on flies and cockroaches represents a potential risk of mechanical transmission to humans. It is, therefore, essential to continue investigations in order to assess the species of bacteria propagated, improve control strategies against these troublesome insects and adopt better hygiene conditions for better living.

The Efficiency of Multi-Range Hydro-Mechanical Stepless Transmission

Aim To determine efficiency of multi-range hydro-mechanical stepless transmis- sion(HMT).Methods Ageneral model of HMT was of HMT was structured.On the basis of power flow analysis, the efficiency was obtained,Results efficiency of multi-range HMT changes continuously with output speed in speed range and is higher than the highest point of the hydraulic efficiency,The volumetric efficiency can potentially result in the speed fluctuation, which can be reduced or eliminated through controlling the ratio of the displacements ofhydraulic unity properly or changing the point of range exchanging .And the mechanical- constant output torque or different output torque under the condition of constant pressure when the transmission works in different parts of a range,Conclusion The multi-range HMT is an ideal stepless transmission with high efficiency.

Application Study of Fractal Theory in Mechanical Transmission

Mechanical transmissions are applied widely in various electrical and mechanical products, but some qualities of some high-end products can＇t meet people＇s demand, and need to be improved with some new methods or theories. The fractal theory is a new mathematic tool, which provides a new approach for the further study in the area of the mechanical transmission, and helps to solve some problems. The basic contents of the fractal theory are introduced firstly, especially the two important concepts, the self-similar fractal and the fractal dimension. Then, the deferent application of the fractal theory in this area are given to display how to further the study and improve some important characteristics of the mechanical transmission, such as contact surfaces, manufacturing precise, friction and wear, stiffness, strength, dynamics, fault diagnosis, etc. Finally, the problems of the fractal theory and its application are discussed, and some weaknesses, such as the calculation capacity of the fractal theory is not strong, are pointed out. Some new solutions are suggested, such as combining the fractal theory with the fuzzy theory, the chaos theory and so on. The new application fields of the fractal theory in the area of the mechanical transmission are proposed.

Adaptive Clutch Engaging Process Control for Automatic Mechanical Transmission

Based on detail analysis of clutch engaging process control targets and adaptive demands, a control strategy which is based on speed signal, different from that of based on main clutch displacement signal, is put forward. It considers both jerk and slipping work which are the most commonly used quality evaluating indexes of vehicle starting phase. The adaptive control system and its reference model are discussed profoundly. Taking the adaptability to different starting gears and different road conditions as examples, some proving field test records are shown to illustrate the main clutch adaptive control strategy at starting phase. Proving field test gives acceptable results.

Strategy to control crawling vehicles with automated mechanical transmission

In order to move vehicles with automated mechanical transmission （AMT） a little bit of distance, such as reversing into or moving in a garage, a control strategy for crawling vehicles was proposed. Based on the dynamic analysis of vehicle starting process and requirements of crawl driv- ing for the vehicle, a control strategy of the clutch was designed. The strategy increased the.slipping friction torque first and then decreased it, in order to realize the crawl driving. The speed increased by the engagement of the clutch, and then the clutch turned to disengage to the half disengage point, when the speed met the requirements. Based on the control strategy, a control software was de- signed. In the end, the software was tested on a vehicle with AMT. The lowest steady vehicle speed was reduced to 40% of the original value, which was set in the control strategy.

Defect Analysis and Innovation Design of Synchronizer for Clutchless Automatic Mechanical Transmission

The synchronizer is a key component of automatic mechanical transmission(AMT)equipped in electric vehicles,but the inertial lock-ring synchronizer(ILRS)commonly used there is not suitable especially for pure electric vehicles without a clutch because of big shift impact.To make the shifting process rapid and smooth,a new synchronizer named pressure-controllable friction ring synchronizer(PCFRS)was designed.Initially,the inevitable shortcoming of ILRS was verified by simulation and test.Furthermore,the mechanical characteristics and advantages of the new synchronizer over ILRS were analyzed.Then,the formulations describing the dynamic transmission based on the working mechanism of the PCFRS were established.Finally,the shifting simulation results with PCFRS and ILRS based on the same operating conditions were compared and analyzed.The research shows that the PCFRS can meet the main shifting evaluation index of an AMT without complex control methods,as well as it takes only 0.2406 s to finish the comfortable and zero-speed-difference shifting.The shifting quality of PCFRS is better than that of the ILRS.It lays a foundation for using the new synchronizer as a part of clutchless AMTs equipped in pure electric vehicles.

OPTIMAL TORQUE CONTROL STRATEGY FOR PARALLEL HYBRID ELECTRIC VEHICLE WITH AUTOMATIC MECHANICAL TRANSMISSION

In parallel hybrid electrical vehicle （PHEV） equipped with automatic mechanical transmission （AMT）, the driving smoothness and the clutch abrasion are the primary considerations for powertrain control during gearshift and clutch operation. To improve these performance indexes of PHEV, a coordinated control system is proposed through the analyzing of HEV powertrain dynamic characteristics. Using the method of minimum principle, the input torque of transmission is optimized to improve the driving smoothness of vehicle. Using the methods of fuzzy logic and fuzzy-PID, the engaging speed of clutch and the throttle opening of engine are manipulated to ensure the smoothness of clutch engagement and reduce the abrasion of clutch friction plates. The motor provides the difference between the required input torque of transmission and the torque transmitted through clutch plates. Results of simulation and experiments show that the proposed control strategy performs better than the contrastive control system, the smoothness of driving and the abrasion of clutch can be improved simultaneously.

PRINCIPLE AND TRANSMISSION TECHNOLOGY OF BERTRAND CONJUGATE SURFACES

Bertrand surface is presented by abstracting and subliming the common characteristic of the usual surfaces including rotational surfaces, developable surfaces, normal circular-arc surfaces, etc. Basic characteristic of Bertrand surface is that normals along generator are coplanar. Bertrand conjugate principle is studied and its basic characteristic is that the instantaneous contact line between a pair of Bertrand conjugate surfaces is generator. Bertrand conjugate can be divided into three kinds of typical conjugation forms in terms of the generators that are general plane curve, circular-arc and straight line. Basic conjugate condition is given respectively, and structure condition, which reflects transmission forms and directrix characteristic of this kind of.conjugation, is researched. As typical engineering application of Bertrand conjugate surface principle, transmission technology of loxodromic-type normal circular-arc bevel gear is studied.

Grey Problems of a Mechanical Transmission System in a Reliability Study

In the light of the Grey characters of reliability on a mechanical transmission system, Grey problems that could assist in the study on mechanical transmission system were analyzed. For example, the factors of time function，the factors of environment and the factors of people have some relationships with the system in this paper. And then, the methods and procedures, which were based upon the theory of Grey system, were elaborated.

Design of hydraulic shift mechanism for AMT vehicles based on the collaborative optimization method

Based on multidisciplinary design optimization（MDO）,a new design method is put forward for hydraulic shift mechanism of heavy-duty vehicle automated manual transmission（AMT）.Taking a shift cylinder for example,the collaborative optimization（CO）method for the design problem of a cylinder is devided into one system level design optimization problem and three subsystem level design optimization problems.The system level is an economic model and the subsystem level is mechanics,kinetics,and a reliability model.Application of the multidisciplinary design optimization software iSIGHT modeling and solving,optimal solution of the shifting cylinder CO model is obtained.According to the optimal solution,oil cylinders are machined out and installed on the gearbox of an AMT system for the bench cycle shift test.The results show that the output force and action speed of the optimized mechanism can meet requirements very well.In addition,the optimized mechanism has a better performance compared to the structure of the traditional design method,which indicates that the CO method can optimize the design of hydraulic transmission.

Optimal gear shift control strategy for positive independent mechanical split path transmission with automatic shift system

An improvement strategy which controls the shift effort and the power summing planetary gear set of steering clutches and brakes have been proposed based on the dynamic model of synchroniser in order to decrease the wear of synchroniser inserts, make gear shift easy and reduce the shock noise for a positive independent mechanical split path transmission which attached an auto- matic shift system when shifting. A kinetics model for the process of synchroniser engagement is built and analyzed in the paper. Thus for optimizing the gear shift process which is divided into three phases a model reference fuzzy self-adaption system is adopted. Through a 6 000 km road experiment, the control strategy has proved feasible and dependable.

Possible Mechanical Transmission of SARS-CoV-2 Causing COVID-19 by Insects: Infection, Prevention, Implications, and Control

The new coronavirus called SARS-CoV-2 is a new type of virus named as COVID-19. Although, it has few similarities with pandemic flu viruses, the respiratory system and immune system are damaged through the viruses infected the population who has weakened immunity. SARS-CoV-2 spreads when people don’t have the sign and symptoms. This virus COVID-19 appears to spread more easily than the flu, and asymptomatic transmission may account for a greater proportion of COVID-19’s spreader over the World. In inundation of the current understanding, the roles of insect vectors are helping in the transmission of viral pathogens as well and the possible roles of some newly joined insects in the mechanical transmission of COVID-19. We also specifically provide the prevention and control methods related to contamination, disease burden, risk pattern in the family, near and dear to maintain the precision of social distancing and development of the immune system to fight against SARS-CoV-2.