Air supply volumes and velocities in cleanrooms are monitored by airflow measuring hoods and anemometers but these measuring methods can be inaccurate if used incorrectly. It is demonstrated in this article that measuring hoods are accurate if the air supply passes evenly out of the hood, as occurs when the air volume is measured from a four-way diffuser or no air supply diffuser. However, when...

The performance of a diffuser in a pump stage depends on its configuration and placement within the stage. The influence of vane shape on the hydrodynamic performance of a diffuser has been studied. The goal of this effort has been to improve the performance of a pump stage by optimizing the shape of the diffuser vanes. The shape of the vanes was defined using Bezier curves and circular arcs. S...

A general theory is presented of optimum diffusion via multi-dimensional 2point transforms over the ring of integers modulo a power of 2. This theory, which makes extensive use of graph-theoretic techniques, establishes the optimality of the transform diffuser used in the cipher SAFER+. A complete characterization is given of the matrix that describes an optimum transform diffuser. Finally, som...

The energy transfer integral between radiating rectangular and detecting circular parallel plates having nonideal angular characteristics is solved for modeling the distance dependence of the irradiance signal. The equation derived for the irradiance signal, which is called the modified inverse-square law, depends on the position, shape, size, and angular characteristics of the light source and...

A new class of diffuser augmented wind turbines (DAWTs) is presented. The new diffuser concept exploits aero-dynamic principles for the creation of high-lift airfoil configurations known from the aircraft industry. Combining this with our objective of obtaining a compact power-efficient design has enabled creation of a family of DAWT designs with energy capture potentials which exceed the power...

This study conducts an experimental study concerning the improvement of nozzle/diffuser micropump design using some novel no-moving-part valves. A total of three micropumps, including two enhancement structures having two-fin or obstacle structure and one conventional micro nozzle/diffuser design, are made and tested in this study. It is found that dramatic increase of the pressure drops across...

Diffused infrared transmission is one of the preferred techniques used in indoor wireless communications. Tolerance to shadowing and a lack of alignm ent requirements are among the many advantages offered by this technique compared to the line-of-sight techniques. However, it has its disadvantages, namely high path loss and multipath dispersion. The limitation imposed by eye-safety requirements...

Joohan Kim Xianfan Xu Purdue University School of Mechanical Engineering West Lafayette, Indiana 47907 E-mail: [email protected] Abstract. Diffuser micropumps are commonly fabricated using the standard lithography techniques with silicon as the base material. The important components of this type of micropumps are flow-directing diffusers and a moving diaphragm. Different diffuser designs show...

The increased performance of close series stacked tube axial fans due to the introduction of a diffuser element between the primary and secondary fan is investigated in this paper. Experimental results showed that there was a 15% increase on average in the performance of two stacked Delta FFB0412VHN 40 mm fans across their operating range when a diffuser element was introduced between the two f...