Northeastern Undergraduate Engineering Review


Digitally Tunable Lowpass-Notch Filter Design for Analog Front-Ends in Brain Signal Measurement Applications

Kaidi Du, Student, Marvin Onabajo, Professor
A digitally tunable Transconductance-Capacitor Low-pass Notch Filter (LPNF) for Electroencephalography (EEG) application is presented in this research report. Since EEG signals fall into four basic frequency bands, δ (1-4Hz), θ (4-8Hz), α (8-13Hz), and β (13-40Hz), but the power line interference at 60Hz, created by electrode cable and circuitry, has much higher power than the brain signals, the power line interference negatively affects the accuracy of the EEG system. Therefore, a combination of a notch filter and a high-order low-pass filter is employed in this work. With the development of microcontrollers, digital control methods are becoming more frequent in integrated circuit (IC) implementations. Hence, a digital tuning method for this LPNF is in high demand. Due to the digital tuning approach, an automatic calibration of this Gm-C LPNF through a microcontroller can be realized in the future.

Design of Liquid Nitrogen Capsules for Forest Fire Suppression

Craig W. Martland, Student, David P. Marchessault, Student, Andrew McGarey, Student, Diego Rivas, Student, Kevin W. Stanley, Student, and Yiannis Levendis, Professor
In recent years forest fires have become increasingly frequent, increasingly large and, hence, increasingly catastrophic. As these fires burn unchecked, firefighters strive to extinguish them by dropping water onto affected areas with aerial delivery methods, such as planes and helicopters. Past research at Northeastern University, showed that direct application of liquid nitrogen is very effective at extinguishing fuel pool fires and, thus, research was initiated to explore the application of liquid nitrogen to forest fires. It is hypothesized that liquid nitrogen would be effective at suppressing forest fires, most likely as a two- part approach. Initial application of liquid nitrogen can suppress the flames and subsequent application of water can extinguish deep-seated fires in the pores of the wood. Herein, as an initial step to realize this approach, a capsule was designed to deliver liquid nitrogen to forest fires. This capsule is designed to insulate the liquid nitrogen and minimize in-transit vaporization, whereas incorporation of exterior fins is expected to impart a controlled spin as the capsule falls from the helicopter. This spin will eject liquid nitrogen, which can create a sprinkling effect as it reaches a crown fire whereas any liquid nitrogen remaining in the capsule will be ejected upon impact and will affect the bottom fire. The capsule is made of a single injection molded piece to be cost-effective. Initial tests proved the insulating, spinning and spilling capabilities of the capsule. No fire tests have been conducted yet.

Maximum Likelihood Image Reconstruction using Data Fusion between X-Ray and Microwave Radar

Matthew T. Tivnan, Student, Carey M. Rappaport, Professor
Data fusion is the process by which measurements collected by two or more sensors are combined to produce a better result than could have been produced by any of the sensors acting individually. X-ray transmission and Microwave Tomography (MWT) are good candidates for data fusion because of their complementary strengths. For example, X-Ray is known for high spatial resolution structural imaging and MWT provides higher contrast in the physical properties for certain applications. In this work, a simple image reconstruction algorithm is presented which utilizes data fusion between X-Ray and MWT measurements. One possible application in neuroimaging is then simulated in a numerical experiment. The final results show that data fusion has significant advantages over conventional approaches.

Programming Acoustic Modems for Underwater Networking

Andrew Tu, Student Member, IEEE, Brian Wilcox, Student Member, IEEE, Mark German, Yashar M. Aval, Member, IEEE, and Stefano Basagni, Senior Member, IEEE
Underwater acoustic communication and networks have attracted significant attention in recent years, with applications ranging from ocean monitoring to off-shore sensor control, and port surveillance. Experimental data are required to test and develop effective underwater networking protocols before underwater networks can be successfully deployed for real world applications. Unfortunately, there are very few permanent underwater acoustic testbeds currently in operation, making it difficult for full scale tests to be conducted. To meet the demands for experimental data, we are working to deploy a permanent underwater acoustic network at the Northeastern University Marine Science Center in Nahant, MA. At the final stage, the network will consist of at least five SM 975 Teledyne Benthos acoustic smart modems, with one wirelessly connected to the shore through a smart buoy of our design. This paper describes the interface for programming these modems and how we used it to implement a fundamental protocol to be used as performance benchmark for more advanced underwater solutions.

Microwave ignition for nanostructured reactive composites

Gianmarco Vella, Student at Advanced Materials Processing Lab (AMPL)
The need for heating at nanoscale has pushed researchers in the study of reactive, nanostructured composites known as nanoheaters. Major topics of interest are the best conditions for consolidation, composition, and ignition of these innovative heat sources. This work presents a new method of ignition for nanoheaters, known as non contact microwave ignition, distinguishing itself from previously developed direct heat application methods. Al-Ni nanoheaters were fabricated through ultrasonic powder consolidation (UPC) with embedded aluminum and copper wires. The conductive properties of the embedded wires, acting as susceptors when exposed to electromagnetic radiation in the microwave range, were found to induce enough heat to Al-Ni nanoheaters to facilitate ignition. This nullifies the requirement of direct heat application to the fabricated nanoheaters to produce ignition. In addition to testing in gaseous environment, this new method of ignition for nanostructured, reactive composites was also tested in vacuum, verifying its effectiveness in a non-gaseous environment.