Research on Vision-based Position Measurement System for Rocket Propellant Loading

In the process of rocket propellant loading, the propellant's own gravity and wind pendulum may cause the connector to exert a large force on the rocket body, which may lead to connector disconnection and fuel leakage, or even damage to the rocket body. To improve the reliability and safety of rocket propellant loading, a position measurement system based on dynamic orientation detection alignment technology is proposed to achieve tracking of the rocket refueling port. In this paper, the two-dimensional position of the target in the camera plane is quickly extracted by identifying the direction of the target image and the size of the marker in the image, while the distance between the target and the camera is accurately obtained by a laser rangefinder. With this measurement solution, the deviation of the connector from the propellant filler port at the current moment can be modified in real time, thus reducing the forces on the rocket and increasing its launch reliability.

Investigation of Active Disassembly in Large Force Applications

Active disassembly (AD) is an emerging field of research in design for disassembly that enables a cost-effective nondestructive separation of product components. It is based on using active joints and fasteners that enables the self-disassembly of products without any direct contact between the product and the operator, where these joints and fasteners must be inserted in the product during its design and manufacturing phases. Generally, active joints and fasteners are made of smart materials such as shape memory alloys (SMAs), that can generate the necessary disassembly forces required to separate the different components of the product. Most of the exerted effort in this field of research was focused on separating products requiring small disassembly forces either in the electronic or automotive sectors. All these active disassembly applications were based on using shape memory alloy snap fits, clips, or wires that are characterized by their ability to generate small forces with large displacements. As, up to the authors knowledge, none of the exerted efforts were concerned with investigating the possibility of using the large disassembly forces that could be generated using shape memory alloy actuators in large force active disassembly applications. Consequently, the presented research aims to examine the possibility of applying active disassembly with products requiring large disassembly forces, having tapered surfaces and large mechanical structure. By presenting two case studies to validate the possibility of using active disassembly with large force applications, in addition to investigating the capability of using shape memory alloy actuators assembled either concentric or eccentric with the product structure.

Initially Clamped Piezoelectric Inchworm Linear Motor Design Based on Force Amplification Mechanisms for Miniaturized and Large Force Actuation Applications

In this paper, a novel monolithic structural design of a piezoelectric (PZT) inchworm motor utilizing three force amplification mode (FAM) mechanisms is presented as an approach to overcome the design challenges of common PZT inchworm motors. A mechanical system model based on Simulink software was developed for a proposed inchworm motor design. The dynamic response of the motor was simulated at the moment of releasing the pre-stressed mechanism. The results showed a backlash response due to the mass acceleration of the mechanisms.

The Antigonid ‘Liberation’ of Athens in 307 BC

This chapter discusses a number of events which were of critical importance to the Antigonids as they continued to build their empire. In 307 BC Antigonus Monophthalmus sent Demetrius Poliorcetes with a large force to make war on Cassander in Greece, using the catchcry of ‘Freedom of the Greeks’ to rally support for the Antigonid cause. Through some good luck, Demetrius was able to land in the Piraeus and evict Cassander’s agent, Demetrius of Phalerum. He then besieged Megara, but was nearly captured when he arranged a mysterious liaison with the famous widow Cratesipolis, though the timing of this event is controversial. This chapter provides an overview of these events and offers some assessment of the outcome of these activities.

Enslaved Labor and Strategies of Subjugation

The Indigenous lands appropriated by Angloamerican settlers could be made profitable only by a large force of low-cost labor. Toward this end, both American Indians and Africans were enslaved, and the settlers developed strategies of subjugation to control them and to maximize profits. These included the construction of persons as property, and their control through racialization, forced reproduction, spatial containment, and social control through violence and terror. Understanding this history allows us to see how these functions continue to be reflected in contemporary forms of structural racism.

Velocity and Force Transfer Performance Analysis of a Parallel Hip Assistive Mechanism

SUMMARYAgainst the backdrop of accelerated ageing around the globe, an increasing number of individuals suffer from hip motion disability and gait disorders. In this paper, the performance analysis of a novel parallel assistive mechanism with 2 DOF for hip adduction/abduction (AB/AD) and flexion/extension (FL/EX) assistance is completed and evaluated, particularly the velocity and force transfer features. The analysis shows that the assistive mechanism has advantages of fine motion assistive isotropy, high force transfer ratio and large force isotropic radius, which indicates that the parallel assistive mechanism is suitable for hip AB/AD and FL/EX assistance.