3,027 research outputs found
A pneumatically driven inkjet printing system for highly viscous microdroplet formation
No full textThis paper introduces a pneumatically driven inkjet printing system that forms highly viscous microdroplets in the nanoliter volume range. The printing system has a unique printing mechanism that uses a flexible membrane and an effective backflow stopper. While typical inkjet systems can handle liquids with a limited range of viscosity due to energy loss by viscous dissipation at the nozzle and ineffective backflow management within their systems, our printing system can print liquids with viscosity as high as 384.5 cP. In the viscosity range 1–384.5 cP, we investigated printing characteristics such as printed droplet volume, standoff distance, and maximum possible frequency. The droplet formation showed outstanding reliability, with the droplet volume exhibiting a coefficient of variation less than 1.07 %. Our printing system can be directly used in inkjet applications with functional liquids over a broad viscosity range.11Nscopu
An inlining approach to formal hardware semantics
No full textThesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (page 61).Hardware components are extremely complex due to concurrency. Modularity has been considered as an effective way to design and understand such complex hardware components. Among various hardware description languages (HDLs), Bluespec allows designers to develop hardware not only based on modularity, but also based on the notion of guarded atomic actions (GAAs). Following the concepts of modularity and GAA, we have been defining a framework called Kami to specify, verify, and synthesize Bluespec-style hardware components. However, modular semantics has an inherent weakness in that it is hard to infer internal changes. In this thesis, I present a new semantic approach based on inlining. Inlining semantics is defined for open hardware systems and resolves the weakness by construction. An implication from modular semantics to inlining semantics is also formally proven; thus the inlining semantics can be used to efficiently prove hardware properties.by Joonwon Choi.S.M
Fixed Input Parameterization for Efficient Prompting
No full textRecent works have shown that attaching prompts to the input is effective at conditioning Language Models (LM) to perform specific tasks. However, prompts are always included in the input text during inference, even when they are fixed, thus incurring substantial computational and memory overhead. Also, there is currently no straightforward method of utilizing prompts that are longer than the maximum input length of the LMs without incurring additional costs during inference. We formally define Fixed Input Parameterization (FIP) problem that focuses on injecting the fixed prompt into the parameters of an LM to be an efficient alternative to attaching fixed prompts to the input. We show that in scenarios with long fixed prompts, FIP can be up to 280 times more efficient in terms of total FLOPs than previous approaches. We further explore methodologies for FIP and show promising results in persona-dependent conversation, semantic parsing, and zero-shot learning with task instructions. Through these explorations, we show that FIP can be a promising direction for conditioning language models, in scenarios with long and fixed prompts
Adversarial Swarm Defence Using Multiple Fixed-Wing Unmanned Aerial Vehicles
No full textThis paper proposes a coverage-based adversarial swarm defence algorithm. The defender swarm composed of fixed-wing unmanned aerial vehicles (UAVs) is assumed to have explosives onboard to intercept an adversarial swarm. The proposed approach consists of two steps: i) impact point optimization and ii) model predictive control (MPC)-based impact time control. The impact point optimization periodically optimizes impact points for the corresponding UAVs to maximize the coverage within the hostile swarm while minimizing the common impact time. The optimization domain is limited to a physically reachable area of UAVs with the common impact time. Besides, the MPC-based impact time controller is designed to ensure the multiple UAVs to arrive the generated time-varying impact points simultaneously. Numerical simulations are performed to prove the feasibility and efficiency of the proposed swarm defence algorithm
Velocity control of nanoliter droplets using a pneumatic dispensing system
No full textThis paper introduces a pneumatic dispensing system to control the velocity of nanoliter droplets with small variation of volume. The system consists of a flexible membrane integrated with a backflow stopper. This unique dispensing mechanism can control the velocity of droplets according to applied positive pressures regardless of other operating conditions and design parameters. The range of droplet velocities is shifted by the flow resistance at the outlet under the same cross-section area. Our dispensing system can eject droplets of desired volume at a velocity that can be easily controlled by selecting design parameters and operating conditions. This dispensing system will provide a reliable performance within an optimized condition stably to deposit droplets onto accurate locations.11Yscopu
Franny Choi, 41st Annual ODU Literary Festival
No full textFranny Choi is a queer, Korean-American poet, playwright, teacher, organizer, pottymouth, GryffinClaw, and general overachiever. She is the author of Floating, Brilliant, Gone (2014), and a chapbook, Death by Sex Machine (2017). She has received awards from the Poetry Foundation and the Helen Zell Writers Program, as well as fellowships from the Vermont Studio Center and the Rhode Island State Council on the Arts. Her poems have appeared in journals including Poetry magazine, American Poetry Review, New England Review, and her work has been featured by the Huffington Post, PBS NewsHour, and Angry Asian Man
Using lazy agents to improve the flocking efficiency of multiple UAVs
No full textA group of agents can form a flock using the augmented Cucker-Smale (C-S) model. The model autonomously aligns them to a common velocity and maintains a relative distance among the agents in a distributed manner by sharing the information among neighbors. This paper introduces the concept of inactiveness to the augmented C-S model for improving the flocking performance. It involves controlling the energy and convergence time required to form a stable flock. Inspired by the natural world where a few lazy (or inactive) workers are helpful to the group performance in social insect colonies. In this study, we analyzed different levels of inactiveness as a degree of control input effectiveness for multiple fixed-wing UAVs in the flocking algorithm. To find the appropriate inactiveness level for each flock member, the particle swarm optimization-based approach is used as the first step, based on the initial condition of the flock. However, as the significant computational burden may cause difficulties in implementing the optimization-based approach in real time, we also propose a heuristic adaptive inactiveness approach, which changes the inactivity level of selected agents adaptively according to their position and heading relative to the flock center. The performance of the proposed approaches using the concept of lazy (or inactive) agents is verified with numerical simulations by comparing them with the conventional flocking algorithm in various scenarios
Crellvm: verified credible compilation for LLVM
No full text© 2018 Copyright held by the owner/author(s).Production compilers such as GCC and LLVM are large complex software systems, for which achieving a high level of reliability is hard. Although testing is an effective method for finding bugs, it alone cannot guarantee a high level of reliability. To provide a higher level of reliability, many approaches that examine compilers' internal logics have been proposed. However, none of them have been successfully applied to major optimizations of production compilers. This paper presents Crellvm: a verified credible compilation framework for LLVM, which can be used as a systematic way of providing a high level of reliability for major optimizations in LLVM. Specifically, we augment an LLVM optimizer to generate translation results together with their correctness proofs, which can then be checked by a proof checker formally verified in Coq. As case studies, we applied our approach to two major optimizations of LLVM: register promotion (mem2reg) and global value numbering (gvn), having found four new miscompilation bugs (two in each).N
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