We take air conditioning (cooling plus humidity control) for granted, and its development is largely due to one man’s “flash” of insight related to thermal principles and basic physics. Part 1 of this article reviewed basic thermal and heat concepts and measurement units related to air conditioning; this part looks at the development of such […]
The development and implementation of air conditioning, Part 1: Heat principles
We take air conditioning (cooling plus humidity control) for granted, and its development is largely due to one man’s “flash” of insight related to thermal principles and basic physics. It’s hard for us today, with the ubiquitous air conditioning (A/C) and mechanical refrigeration we enjoy effortlessly, to grasp how A/C changed our lives: it made […]
Hey, engineers: be grateful you are not epidemiologists! (Part 1: Medical research)
Be honest: The uncertainties of leading-edge engineering R&D are quite modest compared to what medical research faces, especially in areas such as epidemiology. Like many of you, I have been trying to follow many of the numbers related to the Covid-19 virus as well as ongoing vaccine efforts – and I have given up. The […]
Hey, engineers: be grateful you are not epidemiologists! (Part 2: Engineering R&D)
Part 1 of this article looked at the challenges and unavoidable uncertainties facing so much of medical research, and why all-important replication of experiments is so difficult to accomplish. This part looks at the corresponding situation for engineering research and product assessment. After thinking about the medical-research situation, I compared the issues to those related […]
LVDT electronics, Part 2: Interface circuitry
The interface electronics for the LVDT must excite the primary-side winding with a sine wave and then demodulate the two resultant secondary-side waveforms; modern ICs make this analog-signal process fairly straightforward. Part 1 of this FAQ looked at the basics of LVDT excitation, demodulation, and waveforms. This part looks at two standard ICs which implement […]
LVDT electronics, Part 1: Excitation and demodulation
The interface electronics for the LVDT must excite the primary-side winding with a sine wave and then demodulate the two resultant secondary-side waveforms; modern ICs make this analog-signal process fairly straightforward. The first two parts of this LVDT article (see References) looked at the LVDT transducer itself, along with its attributes and history. This second […]
Optical tweezers move nano-objects, Part 3: The system
Part 2 of this article continued the exploration of the basic optical tweezer. This part builds up to a complete system, DIY optical tweezer systems, and extensions to the basic optical-tweezer arrangement. The optical tweezer is obviously not a simple system, and a complete system requires lenses, dichroic mirrors, a laser, video camera, isolation against […]
Optical tweezers move nano-objects, Part 2: The optical path
A combination of optics, lasers, electronics, and combined with advanced physics principles, allows “touch-free” physical manipulation of molecules, viruses, and other nano-sized objects. Part 1 of this article presented the goals of the optical-tweezer design and some of the reasoning which leads to it. This part continues to build up to a larger, complete system. […]
Optical tweezers move nano-objects, Part 1: The Principles
A combination of optics, lasers, electronics, and combined with advanced physics principles, allows “touch-free” physical manipulation of molecules, viruses, and other nano-sized objects. How do you manipulate and move tiny objects such as pieces of DNA or living cells? Conventional mechanical or vacuum tweezers, no matter how small, couldn’t grab them and would cause damage […]
Kelvin 4-Wire sensing solves the “IR Drop” problem
Novice engineers usually don’t learn about this problem and its solution in school, but “practicing” ones learn about it soon enough! Problem: I need to determine the change in resistance of a low-resistance sensor located many meters away. My plan was simply to apply a known voltage across the thin-wire sensor leads and measure the […]