計量論壇

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      作為一名機械工程師，對于動力學，首先浮現在我腦海的是它是應用物理學的一個分支，特別是在經典力學領域中關于力和扭矩及其對運動影響的研究方面。動力學的研究分兩類：線性的（如力、質量/慣性，位移，速度，加速度和動量）和旋轉的（如轉矩、慣性矩/轉動慣量、角位移、角速度、角加速度和角動量)。通常，物體同時做線性和旋轉運動。

As a mechanical engineer, the first thought that comes to my mind is that dynamics is a branch of applied physics, specifically the field of classical mechanics which is concerned with the study of forces and torques and their effect on motion. The study of dynamics falls under two categories: linear (quantities such as force, mass/inertia, displacement, velocity, acceleration and momentum) and rotational (quantities such as torque, moment of inertia/rotational inertia, angular displacement, angular velocity, angular acceleration and angular momentum). Very often, objects exhibit both linear and rotational motion.

Numerous instruments are utilized in “dynamic” legal metrology; some examples are:

• automatic weighing instruments, which can weigh items while in motion,
• electricity meters, which measure of the flow of electrons,
• various types of instruments that measure the flow of water,
• the flow of various other liquids and gases, and
• taximeters.
  

In English, however, the word “dynamic” relates not only to motion but also to change.

One example that highlights this continuous and productive change which encompasses many different sciences (including metrology) and engineering disciplines is space travel. On December 17, 1903 the Wright brothers made the first controlled, self-powered sustained flight. On October 4, 1957, the USSR placed in orbit the Sputnik 1, the first artificial satellite of Earth. On July 20, 1969, the first manned lunar landing was achieved by the United States’ Apollo 11 mission. In 1998 the first components of the International Space Station (ISS), or habitable artificial satellite, were put into low Earth orbit. In 2012, NASA’s Curiosity succeeded in landing on and exploring Mars. More recently in November 2014 the ESA’s Rosetta mission landed its Philae probe on a comet.

In the metrology community we are now seeing significant changes related to the definition of certain SI units as work on the new definition of the kilogram nears completion. Research continues to be successful in refining values and equipment used in the definition and the mise en pratique of other SI units.

While metrology, the science of measurement, is as old as human civilization it continues to constantly change; it continues to see forward acceleration and it continues to be dynamic. It is truly a fascinating time to be a part of this very dynamic work that we call “metrology”.

When we reflect on the rapid pace of change in the 21st century, we may say that “the only thing that is constant is change itself”. The needs for metrology, and how these needs are met, are no exceptions; it is a challenge to bring the benefits of a stable and accurate measurement system to a dynamic world.

Many of the needs of society are met by new technologies, and it is essential that stable and accurate measurements are available to underpin them.

The accurate knowledge of dynamic quantities is pivotal to progress in high technology whether it is the high-speed movements in a disk drive, the variations in supply and demand from renewable energy sources on electricity grids, or the drive for environmental improvement and fuel efficiency in the aerospace industry. Dynamic quantities also play an increasing role in established industries, such as the dynamic weighing of trains and trucks, and the monitoring of vibration and impact arising from the tyres and engines of cars.

These applications of dynamic measurement bring particular challenges. Linking highly accurate long-term stable standards to dynamic in situ measurements in everyday applications is difficult and itself requires great innovation.

Adapting our measurement capabilities to a dynamic world requires other steps too. The need to ‘future proof’ the International System of Units (the SI) is one of the key drivers for the redefinition planned for 2018. The changes will ensure the benefits of greater universality of the world’s measurement system, and open new opportunities for scientific and technological advances in the future.

We all need dynamic people in dynamic organisations to address the challenges of measurement in a dynamic world.

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