Vibration attenuation control of ocean marine risers with axial-transverse couplings

The target of this paper is designing a boundary controller for vibration suppression of marine risers with coupling mechanisms under environmental loads. Based on energy approach and the equations of axial and transverse motions of the risers are derived. The Lyapunov direct method is employed to formulated the control placed at the riser top-end. Proof of existence and uniqueness of the solutions of the closed-loop system is provided. Stability analysis of the closed-loop system is also included

Nonlinear Control of Flexible Two-Dimensional Overhead Cranes

Considering gantry cable as an elastic string having a distributed mass, we constitute a dynamic model for coupled flexural overhead cranes by using the extended Hamilton principle. Two kinds of nonlinear controllers are proposed based on the Lyapunov stability and its improved version entitled barrier Lyapunov candidate to maintain payload motion in a certain defined range. With such a continuously distributed model, the finite difference method is utilized to numerically simulate the control system. The results show that the controllers work well and the crane system is stabilized

The First Record of Metaphire Birmanica (Rosa, 1888) in Vietnam, with Notes on Several Earthworm Species

The Amynthas and Metaphire species recorded in Vietnam have been rechecked based on original descriptions and preserved specimens. As a result, Metaphire birmanica (Rosa, 1888) is recorded in Vietnam for the first time. The species is recognized by having three pairs of spermathecal pores in 5/6/7/8, male pores in xviii, presence of copulatory pouches, no genial markings, and manicate intestinal caeca. In addition, three species have been rechecked and re-assigned to different genera, namely Amynthas tripidoporophoratus (Thai & Nguyen, 1993) comb. nov., Metaphire dranfocana (Do & Huynh, 1993) comb. nov., Metaphire anhumalatana (Thai & Huynh, 1993) comb. nov

Payload motion control for a varying length flexible gantry crane

Cranes play a very important role in transporting heavy loads in various industries. However, because of its natural swinging characteristics, the control of crane needs to be considered carefully. This paper presents a control approach to a flexible cable crane system in consideration of both rope length varying and system constraints. At first, from Hamilton\u27s extended principle the equations of motion that characterized coupled transverse-transverse motions with varying rope length of the gantry are obtained. The equations of motion consist of a system of partial differential equations. Then, a barrier Lyapunov function is used to derive the control located at the trolley end that can precisely position the gantry payload and minimize vibrations. The designed control is verified through extensive experimental studies

Síntesis de interpolación de los controladores para un sistema de accionamiento eléctrico multimotor que contiene un elemento enlazado elásticamente

Partial differential equations, integral, differential, or other equations describe multi-motor automatic electric drive systems containing elastic conveyor belts. Because of the elastic and distributive nature of the system parameters, the transfer function describing them is often a complex expression, containing not only the arguments as a linear system but also the inertial and transcendental components. This makes the precise control of tension and speed synchronously much more complicated than the centralized parameter system. A promising numerical solution based on the real interpolation method will simplify the procedure for synthesizing control loops while preserving the characteristic properties of objects with distributed parameters. The objective of the study is to propose a feasible solution for synthesizing the regulators based on the real interpolation method; it allows direct operation with the original transfer function containing the inertial and transcendental components. In this paper, we proposed an approach to synthesize the control system for objects with distributed parameters using the real interpolation method to reduce computational capacity and synthesis error while preserving the properties of this object class. Building an experimental model of the two-motor electric drive system containing an elastic conveyor to verify the effectiveness of the proposed algorithm. The simulation and experimental results indicate that the control system with the received regulators operating stably and meets the required quality criteria. It proves the efficiency of the synthesis algorithm based on the real interpolation method.Introducción: los sistemas de accionamiento eléctrico multimotor que incluyen transportadores elásticos son un ejemplo de sistemas típicos con parámetros distribuidos descritos por ecuaciones complejas. Debido a la naturaleza elástica y distributiva de los parámetros del sistema, la función de transferencia que los describe suele ser una expresión compleja que contiene los componentes inercial y trascendental. Problema: la naturaleza elástica y distributiva de los parámetros del sistema hace que el control preciso de la tensión y la velocidad sincrónicamente sea mucho más complicado que el sistema de parámetros centralizados. Metodología: se propone una solución numérica para sintetizar los reguladores basada en el método de interpolación real para reducir la capacidad computacional y el error de síntesis preservando las propiedades características de los objetos con parámetros distribuidos. Conclusión: la eficacia del algoritmo propuesto se verifica mediante un modelo experimental del sistema de accionamiento eléctrico de dos motores que contiene un transportador elástico. Los resultados de simulación y experimentales indican que el sistema de control con los reguladores recibidos opera de manera estable y cumple con los criterios de calidad requeridos. Originalidad: los resultados de la investigación se pueden aplicar en el desarrollo de sistemas centrales de control y monitoreo para líneas de producción automáticas con sistemas de accionamiento multimotor que incluyen transportadores

Analysis of distributed ledger technologies for industrial manufacturing

In recent years, industrial manufacturing has undergone massive technological changes that embrace digitalization and automation towards the vision of intelligent manufacturing plants. With the aim of maximizing efficiency and profitability in production, an important goal is to enable flexible manufacturing, both, for the customer (desiring more individualized products) and for the manufacturer (to adjust to market demands). Manufacturing-as-a-service can support this through manufacturing plants that are used by different tenants who utilize the machines in the plant, which are offered by different providers. To enable such pay-per-use business models, Distributed Ledger Technology (DLT) is a viable option to establish decentralized trust and traceability. Thus, in this paper, we study potential DLT technologies for efficient and intelligent integration of DLT-based solutions in manufacturing environments. We propose a general framework to adapt DLT in manufacturing, and then we introduce the use case of shared manufacturing, which we utilize to study the communication and computation efficiency of selected DLTs in resource-constrained wireless IoT networks

New Blind Muti-signature Schemes based on ECDLP

In various types of electronic transactions, including election systems and digital cash schemes, user anonymity and authentication are always required. Blind signatures are considered the most important solutions to meeting these requirements. Many studies have focused on blind signature schemes; however, most of the studied schemes are single blind signature schemes. Although blind multi-signature schemes are available, few studies have focused on these schemes. In this article, blind multi-signature schemes are proposed based on the Elliptic Curve Discrete Logarithm Problem (ECDLP). The proposed schemes are based on the GOST R34.10-2012 digital signature standard and the EC-Schnorr digital signature scheme, and they satisfy blind multi-signature security requirements and have better computational performance than previously proposed schemes. The proposed schemes can be applied in election systems and digital cash schemes