Quasi-Periodic Oscillations of Roll System in Corrugated Rolling Mill in Resonance

This paper investigates quasi-periodic oscillations of roll system in corrugated rolling mill in resonance. The two-degree of freedom vertical nonlinear mathematical model of roller system is established by considering the nonlinear damping and nonlinear stiffness within corrugated interface of corrugated rolling mill. In order to investigate the quasi-periodic oscillations at the resonance points, the Poincaré map is established by solving the power series solution of dynamic equations. Based on the Poincaré map, the existence and stability of quasi-periodic oscillations from the Neimark-Sacker bifurcation in the case of resonance are analyzed. The numerical simulation further verifies the correctness of the theoretical analysis.

REDUCING THERMAL INERTIA TO IMPROVE THERMAL COMFORT BY CONFIGURATION OF A NEW BRICK

Climate change has changed seasons, affecting the indoor temperature of buildings and causing a strong feeling of discomfort, especially in hot weather. This feeling of discomfort is mainly due to thermal inertia. The aim of this work is to reduce the indoor temperature of buildings by using a new brick with a low thermal inertia. As part of this work we have designed a brick with the same characteristics as the ordinary ones but which are perforated so that in the construction of the wall they form a conduit for the transport of air. The latter thus acts as a heat transfer fluid in its upward convective movement, bringing with it the heat stored in the wall. In order to improve thermal exchange, an air-extractor roller system has been installed. This air extractor allows to increase convection in the walls, reducing thermal inertia and implicitly improving thermal comfort.

Coupling Modeling and Analysis of the Tension System for Roll-to-Roll Gravure Printing Machines

Control accuracy of tension system is an important index in roll-to-roll gravure printing machines. However, the complex relationships of the tension system make the problem of coupling model difficult to be solved, which has limited the improvement of tension control accuracy. Therefore, a coupling mechanism model of global tension system is established and analyzed for the gravure printing machines in this study. According to the working principles and assumptions, tension model of the two-roller system is derived by considering the effects of drying temperature, and then the tension models of subsystem including unwinding subsystem, printing subsystem and rewinding subsystem are established. Based on these, the global coupling mechanism model of the tension system is established for roll-to-roll gravure printing machines. Finally, the coupling model is analyzed by MATLAB simulation, and the simulation results show that the tension system model established in this paper can accurately reflect the characteristics of tension system.

Magnetic peristaltic pumps for stowing operations

Relevance of the work. The use of laying the workings is intended to increase the safety of mining operations, namely, controlling mining pressure, reduce mineral loss during excavation, prevent the occurrence of underground fires, and reduce the risks of destruction of objects in residential areas. Methodology of the work. The article is devoted to the study of the possibility of applying the system of peristaltic transportation of pasty slurries using the energy of a traveling magnetic field to work on the laying of the goaf. Taking into account the features of the materials used as the basis for filling mixtures, the specifics of the process of moving the latter to the place of laying, innovative technologies for transporting filling mixtures are becoming increasingly important. Results and scope. A fundamentally new approach to the transportation of liquid and viscous media is the use of low-frequency magnetic peristaltic pumps. The design of this pump involves the use as an executive body of the working channel, made of a magneto-active elastomer. By its extension under the influence of a traveling magnetic, periodic waves of local deformation pass, moving the filling mixture. Conclusions. The rejection of the traditional roller system, which presses the channel, and the replacement of the main executive body of the pump with the working channel, the structuring flow and preventing its separation, will expand the scope of application of pumping equipment during filling operations. The pressure developed by the pump depends on the energy characteristics of the traveling magnetic field. Studies have shown that the speed of movement of a wave of local deformation when moving various materials is sufficiently stable and slightly depends on the viscosity of a substance.

Measurement of push-rim forces during racing wheelchair propulsion using a novel attachable force sensor system

To improve competitive skills, it is important to clarify the relationship between the propulsion motion (the propulsive force in the use of racing wheelchairs optimized for athletes) and aerodynamic drag, which can change during propulsive motion. Therefore, the purpose of this research was to construct a novel force sensor system that is attachable to racing wheelchairs for individual athletes and usable in a wind tunnel facility to examine differences in the push-rim force characteristics of athletes based on the measured results. The system was composed of four two-dimensional component force sensors, batteries, and radio transmitters. From the output of the four two-dimensional component sensors, tangential and radial components of the push-rim force were measured. Three top-class long-distance wheelchair athletes participated in this study, which required each athlete to push a racing wheelchair at 5.56 m/s on a wheelchair roller system in a wind tunnel facility. The force sensor system was mounted on the participants’ individual racing wheelchairs. The measured tangential force waveforms were classified as either bimodal or unimodal depending on the athletes’ propulsion styles. Although two athletes showed similar propulsion style characteristics, the athlete with more years of experience showed better propulsive work efficiency and repeatability. Therefore, a difference in skill for applying propulsive force during the push phase, which is difficult to estimate by kinematic analysis, could be estimated by using the force sensor system.

The Restoration of the Betty’s Hope North Windmill, Antigua, West Indies

Chapter 14 investigates the archaeology, technology, and restoration of the Betty’s Hope north windmill. Archaeological excavations and restoration work were conducted from 1988 to 1995. Today, 90 stone towers are all that remain of the windmills scattered across Antigua’s landscape. This project initiated archaeological research at Betty’s Hope as well as cultural heritage management of the site. As one of the largest and most lucrative estates on Antigua, Betty’s Hope could afford two windmills to crush the sugar cane by harnessing wind power and utilizing the horizontal three-roller system. The mid-nineteenth century witnessed the conversion to steam-powered at Betty’s Hope. Restoration efforts included replacing parts of the original stone floor, old hard wood beams, masonry, cap house, arms, and machinery.

Nonlinear time-delay feedback controllability for vertical parametrically excited vibration of roll system in corrugated rolling mill

This paper investigates vibration characteristics of the corrugated roll system and designs a time-delay feedback controller to control the parametrically excited vibration of system. The model of parametrically excited nonlinear vertical vibration of roller system is established by considering the nonlinear damping and nonlinear stiffness within corrugated interface of corrugated rolling mill. The approximate analytical solution and amplitude-frequency characteristic equations of principal resonance and sub-resonance of roller system are obtained by using the multiple-scale method. The influences of nonlinear stiffness coefficient, nonlinear damping coefficient, system damping coefficient and rolling force amplitude on vibration are further analyzed. The time-delay feedback controller is designed to eliminate the jump and hysteresis phenomenon of the roll system and numerical simulation results demonstrate the effectiveness of the controller. The analysis results provide some theoretical guidance for vibration suppression of roller system of corrugated rolling mill.