On the connectedness of planar self-affine sets

In this paper, we consider the connectedness of planar self-affine set $T(A,\mathcal{D})$ arising from an integral expanding matrix $A$ with characteristic polynomial $f(x)=x^2+bx+c$ and a digit set $\mathcal{D}=\{0,1,\dots, m\}v$. The necessary and sufficient conditions only depending on $b,c,m$ are given for the $T(A,\mathcal{D})$ to be connected. Moreover, we also consider the case that ${\mathcal D}$ is non-consecutively collinear.Comment: 18 pages; 18 figure

Surface micromachined electrostatically actuated micro peristaltic pump

An electrostatically actuated micro peristaltic pump is reported. The micro pump is entirely surface micromachined using a multilayer parylene technology. Taking advantage of the multilayer technology, the micro pump design enables the pumped fluid to be isolated from the electric field. Electrostatic actuation of the parylene membrane using both DC and AC voltages was demonstrated and applied to fluid pumping based on a 3-phase peristaltic sequence. A maximum flow rate of 1.7 nL min^–1 and an estimated pumping pressure of 1.6 kPa were achieved at 20 Hz phase frequency. A dynamic analysis was also performed with a lumped-parameter model for the peristaltic pump. The analysis results allow a quantitative understanding of the peristaltic pumping operation, and correctly predict the trends exhibited by the experimental data. The small footprint of the micro pump is well suited for large-scale integration of microfluidics. Moreover, because the same platform technology has also been used to fabricate other devices (e.g. valves, electrospray ionization nozzles, filters and flow sensors), the integration of these different devices can potentially lead to versatile and functional micro total analysis systems (µTAS)

Integrated surface-micromachined mass flow controller

An integrated surface-micromachined mass flow controller (MFC) that consists of an electrostatically actuated microvalve and a thermal flow sensor is presented here. With a unique design and utilizing a multilayer Parylene process, the active microvalve and the flow sensor are integrated onto a single chip to perform closed-loop flow control. Sensitivity of the flow sensor is 55 μV/(μ/L/min) for airflow and 12.2 μV/(nL/min) for water. The valve is actuated with a 10 kHz AC signal and an applied pressure of 21 kPa can be sealed with an actuation voltage of 200 V_peak (±200 V). For flow control, both Pulse Width Modulation (PWM) and actuation voltage adjustment are demonstrated. PWM shows better performance in terms of controllability and linearity

Surface micromachined and integrated capacitive sensors for microfluidic applications

We have demonstrated an entire series of capacitive sensors using a multi-layer parylene/photoresist surface micromachining technology. The developed sensors are designed for total integration into parylene-based microfluidic systems for real-time system monitoring. Sensors have been demonstrated for the following applications: in-line pressure sensing (range: 0-35 kPa, resolution: 0.03 kPa); liquid front position and/or volumetric measurements (range: 0->50 pL, resolution: <5 pL); and dielectric measurements, which can be used to deduce fluid properties such as liquid composition. The reported sensor technology demonstrates versatility, high sensitivity, small footprints, and easy integration

Compact Furniture Dolly

One problem faced by people during moving is how to move large pieces of furniture, i.e. sofa, mattress, table, refrigerator, etc., conveniently without damaging them. A typical small dolly is incapable of carrying such large pieces, and a bulky dolly is inappropriate for an indoor use because it can damage the furniture and the floor. Besides, in either case, the user should lift up and put the load on the dolly. People who want to change positions of their furniture regularly to get a fresh look for the house, it is cumbersome to call a moving company every time. Our team aims to design a dolly system that can load large pieces of furniture onto adjustable frames with multiple wheels so that the user can tow or push furniture without hassle. The lift function of the dolly can jack up the furniture by pushing up the bottom of the furniture. The lift system does not require much power so that most people can easily load furniture onto the system. The frames are extendable for various types of furniture. When not in use, the system can be disassembled and stowed easily

3D Printed Biliary Anatomy for Surgical Planning

Background: Studies demonstrated that 3D-printed livers from CT or MRI data can be accurate models of actual patient anatomy. However, it has yet to be established if 3D printing offers improvements to clinical outcomes in surgery. This project seeks to optimize these applications for use at Jefferson by producing 3D-printed models from patient CT scans to guide liver resection surgeries. Methods: A liver transplant attending was interviewed about challenges encountered during hepatectomies. A publicly available abdominal computed tomography scan was used to render a liver and its vasculature in 3DSlicer. The liver surface was cut into two halves in MeshMixer to allow visualization of the underlying vasculature. These models were printed using an Ultimaker S5. Results: We successfully 3D printed a model of a liver capsule containing branches of the right and left hepatic arteries. The processing time included 3 hours to render liver anatomy and 31 minutes to edit the model into a form best suited for visualization of internal structures. The printing time was 47 hours and 25 minutes. 232g of PLA, 51g of Breakaway, and 24g of polyvinyl alcohol were used to create the model. Conclusions: Creation of 3-D printed models of biliary anatomy is feasible, time-efficient, and inexpensive. In future work, we plan to encapsulate the hepatic vasculature and biliary tree (and potentially also the tumor when applicable) into a translucent silicone model of the liver parenchyma, using a 3D-printed liver shell as a mold. This silicone model could be used pre-operatively and intra-operatively to help plan and guide the surgery. Measurable endpoints will include procedure time and intra-operative blood loss. This work has the potential to improve surgical outcomes for patients while facilitating the work of the surgeons

Modelling and control of a hybrid electric propulsion system for unmanned aerial vehicles

This paper presents the modelling and control of a hybrid electric propulsion system designed for unmanned aerial vehicles. The work is carried out as part of the AIRSTART project in collaboration with Rotron Power Ltd. Firstly, the entire parallel hybrid powertrain is divided into two powertrains to facilitate the modelling and control. Following this, an engine model is built to predict the dynamics between the throttle request and the resulting output. It is then validated by comparing with experimental data. On the basis of d-q model of the motor/generator, a good estimation of torque loss at steady state is achieved using the efficiency map. Next, a rule-based controller is designed to achieve the best fuel consumption by regulating the engine to operating around its ideal operating line. Following the integration of the models and controller, the component behaviour and control logic are verified via the final simulation. By enabling the engine to operate at its best fuel economy condition, the hybrid propulsion system developed in this research can save at least 7% on fuel consumption when compared with an internal combustion engine powered aircraft