Test & Measurement

A Brief History of Modern Digital Shaker Controllers

Over a period of 40 years, four generations of digital vibration exciter control systems have been developed by various companies in the USA. They are categorized as standalone, PC-based, PC-tethered, and fully networked. This paper discusses the evolution and improvement of shaker controllers and the critical parameters that users should consider during the acquisition process.

Posted in: White Papers, Test & Measurement


Force Transfer Machines

There has been ongoing debate as to whether or not a hydraulic force machine that applies the force simultaneously to both the reference standard and the unit under test is more repeatable and reproducible when the force is applied and transferred with 3 bars versus 2 bars. The debate centers around alignment of the reference standard and the unit under test. There is no disagreement about the benefits of using a triangular configuration when using multiple load cells to weigh an object; however, there is a debate over any advantages that might be offered by using a 3 bar Universal Calibrating Machine (UCM) instead of a traditional 2 bar system. This paper provides test results for repeatability and reproducibility for a 2 bar UCM and a 3 bar UCM, showing the null hypothesis to be correct and proving that there is not a difference between either type of UCM.

Posted in: White Papers, Instrumentation, Mechanical Components, Test & Measurement


Full RF Signal Chains from 0 Hz to 110 GHz

Analog Devices (ADI) has expanded its RF capabilities in the full signal chain, including companion products, in the full bandwidth from 0 Hz to 110 GHz.This white paper provides examples of the wider frequency spectrum covered by ADI, and explains that true DC is important. Off signal chain performance is also critical, and this paper shows how low-noise, high-stability control and power components are important to overall RF signal performance.

Posted in: White Papers, Electronics, Semiconductors & ICs, Data Acquisition, Sensors, Test & Measurement


Basics of Electric Heaters

Hotwatt has manufactured specialized electric heating elements for over 64 years, all made in the USA. Products include cartridge, air process, immersion, strip and finned strip, tubular and finned tubular, band, compressor crankcase, foil, flexible rope and ceramic heaters. We are a quality supplier to OEM's in the in industrial, medical, commercial appliance, packaging, instrumentation, aviation, transportation and military fields.

Posted in: White Papers, White Papers, Electronics, Electronics & Computers, Instrumentation, Test & Measurement


Computer Aided Design of Suspension Mechanisms

Automobile suspension mechanisms have to date been designed using two-dimensional graphic oriented methods. Computer-aided design has allowed many two-dimensional mechanisms to be designed much more accurately. However, this has not translated to suspension mechanisms because these mechanisms are not two-dimensional but instead three-dimensional.

Posted in: White Papers, Electronics & Computers, Manufacturing & Prototyping, Software, Test & Measurement


Live-Cell Microscopy and Traction Force Measurements with Simulated Microgravity “Clinochip”

Goddard Space Flight Center, Greenbelt, Maryland The deleterious effects of microgravity are undeniable: reduced bone mineral density, muscle atrophy, vascular remodeling, etc. These health issues may derive from both systemic factors, and from direct alterations to intracellular components and in the local microenvironment around cells. To understand the biological mechanisms at play, detailed studies have been performed in spaceflight. However, because experiments on the International Space Station (ISS) can be prohibitively expensive, clinostats are an alternative ground-based analogue for cellular studies. Clinostats “randomize” the orientation of gravity with respect to the cell fixed-frame, thereby simulating microgravity by eliminating a preferential gravity direction.

Posted in: Briefs, TSP, Test & Measurement, Medical, health, and wellness, Biomechanics


Comparison of Three Methods for Measuring Distortion in Optical Windows

A new method for quantifying distortion based on phase-shifting interferometry has been developed. John F. Kennedy Space Center, Florida The primary function of a window is to allow observation of, and protection from, a potentially hazardous environment. Yet, from the window designer’s point of view, ensuring protection from weather conditions in home windows; from wind, temperature, and airborne debris in automotive windows; and from extreme pressures and temperatures in aircraft and spacecraft windows has almost always taken precedence over image quality. It is more important to protect an astronaut from the vacuum of space than to provide clear imagery, yet these are not exclusive requirements. Advances in materials and material processing allow the designer to attain better optical performance while not sacrificing important material specifications such as strength. In addition, increased performance demands on spacecraft windows — which are now used for photography, telescope observation, and laser communications — require greater consideration of optical clarity.

Posted in: Briefs, TSP, Test & Measurement, Windows and windshields, Finite element analysis, Visibility, Spacecraft


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