a numerical model for simulating residence time distribution (rtd) of turbulent flows in helical static mixers is proposed and developed to improve the understanding of static mixers. the results of this model is presented in terms of different volumetric flow rate to illustrate the complicated flow patterns that drive the mixing process in helical static mixers. the computed results are also u...

An analysis is presented for the conversion loss and noise of microwave and millimeter-wave mixers. The analysis includes the effects of nonlinear capacitance, arbitrary embedding impedances, nonideality of microwave diodes, and shot, thermal, and scattering noise generated in the diode. Correlation of downconvertd components of the time-varying shot noise is shown to explain the “anomalous” no...

An overview of monolithic radio-frequency (RF) active mixer design is presented. The paper is divided into two parts. The first part discusses the performance parameters that are relevant to the design of downconversion mixers, and how they affect the system performance. The second part presents three common kinds of mixer topologies, namely, unbalanced, singlebalanced, and double-balanced desi...

The two signals inserted into the two input ports are usually the Local Oscillator signal, and the incoming (for a receiver) or outgoing (for a transmitter) signal. To produce a new frequency (or new frequencies) requires a nonlinear device. In a mixing process if we want to produce an output frequency that is lower than the input signal frequency, then it is called down-conversion and if we wa...

Micromixing is a crucial process within microfluidic systems such as micro total analysis systems (μTAS). A state-of-art review on microstructured mixing devices and their mixing phenomena is given. The review first presents an overview of the characteristics of fluidic behavior at the microscale and their implications in microfluidic mixing processes. According to the two basic principles expl...

A planar active retrodirective four-element array with subharmonic phase conjugation mixers based on anti-parallel diode pairs (APDPs) is proposed. As compared to previous phase conjugation mixers using twice RF frequency for LO frequency, the proposed conjugation mixers need only half RF frequency so that it can be easily applied for millimeter-wave applications. Receive, transmitting, local o...

Nowadays, utilisation of Nano-materials as one of the most recent methods of bitumen modification has attracted attention of many researchers. However, not enough research has been pursued on their mixing with bitumen, because of their dimensions and specific properties. In this study, the carbon Nano-tubes were mixed with bitumen using different mixers and some images were recorded employing a...

Envelope distortion in transconductance mixers is analyzed in this paper. The analysis consists of a simplified theoretical study, simulation results, and measurements about several implemented mixers. The studied mixers are active single-balanced and double-balanced structures. A theoretical mismatch analysis is carried out instead of a complex mixer nonlinearity analysis; this gives an intuit...

We are currently exploring ways to improve the performance of SIS mixers above 700 GHz. One approach is to use NbTiN in place of Nb for all or some of the mixer circuitry. With its high gap frequency and low losses demonstrated up to 800 GHz, it should be possible to fabricate an all-NbTiN SIS mixer with near quantumlimited noise performance up to 1.2 THz. Using a quasioptical twin-slot two-jun...