Microscale Freeform Integration by Directed Self Assembly

Most solid freeform fabrication (SFF) manufacturing processes assemble uniform components such as powder particles or polymer chains to produce desired geometries. Their capacity for producing highly functional parts (integrated actuation, sensing, and electronics) will dramatically increase when multiple materials and functional subcomponents can be automatically integrated. This paper addresses criteria for a system that integrates multiple materials and components through computer-controlled self-assembly. It builds complex systems from layers of self-assembled micro-components. The paper will address implementation methods, present a concept demonstration, and consider its application to micro-thermoelectric systems. This manufacturing process can be enhanced further through integration with mature additive processes.Mechanical Engineerin

2017-2018 AIAA DBF Discovery Day Abstract

The objective of the 2017-2018 American Institute of Aeronautics and Astronautics Design Build Fly competition is to simulate a passenger aircraft that carries passengers and cargo, while also being able to support Line Replaceable Units. The remotely controlled aircraft will demonstrate its capability to complete three flight missions and one ground mission during a “fly-off” in Wichita, Kansas. The payload consists of five different sized bouncy balls as passengers and an 8oz payload block with linear dimensions adding to 9”. The score is inversely proportional to wingspan and empty weight. To complete the missions, the team researched and developed an aircraft with a low aspect ratio wing in low Reynolds Number flow. There is little prior research done in this niche, so new design, manufacturing, and testing processes were needed. This year-long project begins with design and manufacturing studies in the fall semester. The spring semester is dedicated to iterating the design and communicating results. A biplane with two-foot wingspan was developed for the competition. It can complete all missions within specifications. A final design report was written and submitted to the competition. The final fly-off is the last weekend in April in Wichita, KS

Spectral Absorption Coefficient of Additive Manufacturing Polymers

As NASA turns to additive manufacturing processes, there is a need to ensure that the parts they produce are reliable. This is especially true when creating parts in space, where resources are limited and failure could result in catastrophe. Active thermography has shown potential as a non-destructive quality assurance technique for additive manufacturing processes. Heat transfer models used in active thermography techniques require accurate material property measurements in order to extract useful information about the system, including defect location. The spectral absorption coefficient, which determines the depth at which radiative power is absorbed into a surface, is a material property necessary for performing active thermography on AM polymers. This paper presents measurements of spectral absorption coefficients of polymers commonly used in additive manufacturing. Spectral absorption coefficients for fully dense PLA, ABS, and Nylon 12 samples are reported. Future work is needed to measure the spectral absorption coefficients of different materials and colored filaments commonly used in additive manufacturing

Fabrication of Demineralized Bone Matrix/Polycaprolactone Composites Using Large Area Projection Sintering (LAPS)

Cadaveric decellularized bone tissue is utilized as an allograft in many musculoskeletal surgical procedures. Typically, the allograft acts as a scaffold to guide tissue regeneration with superior biocompatibility relative to synthetic scaffolds. Traditionally these scaffolds are machined into the required dimensions and shapes. However, the geometrical simplicity and, in some cases, limited dimensions of the donated tissue restrict the use of allograft scaffolds. This could be overcome by additive manufacturing using granulated bone that is both decellularized and demineralized. In this study, the large area projection sintering (LAPS) method is evaluated as a fabrication method to build porous structures composed of granulated cortical bone bound by polycaprolactone (PCL). This additive manufacturing method utilizes visible light to selectively cure the deposited material layer-by-layer to create 3D geometry. First, the spreading behavior of the composite mixtures is evaluated and the conditions to attain improved powder bed density to fabricate the test specimens are determined. The tensile strength of the LAPS fabricated samples in both dry and hydrated states are determined and compared to the demineralized cancellous bone allograft and the heat treated demineralized-bone/PCL mixture in mold. The results indicated that the projection sintered composites of 45–55 wt %. Demineralized bone matrix (DBM) particulates produced strength comparable to processed and demineralized cancellous bone

Strengthening porous metal skeletons by metal deposition from a nanoparticle dispersion

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references.The accuracy of solid freeform fabrication processes such as three-dimensional printing (3DP) and selective laser sintering (SLS) must be improved for them to achieve wide application in direct production of metal parts. This work seeks to reduce sintering and deformation of porous metal skeletons during liquid-metal infiltration by reinforcing the skeletons with metal deposits. This can be accomplished by depositing a metal from a suspension of nanometer-scale iron particles. The nanoparticle deposits from the suspension concentrate in regions of high stress when the solvent is removed by drying. The particles are sintered to create a dense structure that reinforces the porous skeleton-reducing deformation and creep. Generically, this work studies a process for metal deposition from a liquid carrier with unique transport characteristics compared to traditional metal deposition processes such as plating, chemical vapor deposition, evaporation, and sputtering. This process of depositing metal from nanoparticle suspensions is studied using a commercial product of iron nanoparticles. The processed iron particle suspension contains significant carbon from the organic dispersants used to stabilize the suspension. Gas adsorption, X- ray diffraction, and SEM imaging were used to show that the carbon aids reduction of any iron oxide on heating and strongly influences the densification characteristics. The iron nanoparticles are applied to porous steel skeletons produced by sintering stainless steel powder. These are then heated to typical steel infiltration temperatures of 1284 C. The nanoparticle deposits are shown to reduce creep deflections at infiltration temperatures by up to 95% and reduce shrinkage by up to 60%.(cont.) The best results are obtained by repeating the process of applying the nanoparticles, drying the solvent, and sintering them to 700 C up to four times. The performance in magnetic materials can also enhanced by applying a magnetic field along the magnetic particles. This magnetic field concentrates the nanoparticle deposits into the contact points between the skeleton particles where they provide optimal benefit.by Nathan Brad Crane.Ph.D

IMECE2008-68023 ANALYSIS OF ERROR SENSITIVITY OF A SYSTEM FOR ELECTROWETTING FORCE MEASUREMENT

ABSTRACT Electrowetting systems are commonly studied by measuring contact angle changes with applied voltage. However many applications such as digital droplet manipulation require information about the force applied to a drop to improve performance. This paper analyses a previously demonstrated method of measuring the electrowetting forces to estimate the sensitivity of force measurements to potential errors such as droplet evaporation, variation in volume, and alignment accuracy. The most significant force errors are introduced by uncertainty in droplet volume as by evaporation. However, analysis shows that this can be controlled by lowering the measurement tip to compensate for evaporation. Errors in tangential force due to alignment are shown to be small for alignment errors below 1º

Deterministic constant-depth preparation of the AKLT state on a quantum processor using fusion measurements

The ground state of the spin-1 Affleck, Kennedy, Lieb and Tasaki (AKLT) model is a paradigmatic example of both a matrix product state and a symmetry-protected topological phase, and additionally holds promise as a resource state for measurement-based quantum computation. Having a nonzero correlation length, the AKLT state cannot be exactly prepared by a constant-depth unitary circuit composed of local gates. In this work, we demonstrate that this no-go limit can be evaded by augmenting a constant-depth circuit with fusion measurements, such that the total preparation time is independent of system size and entirely deterministic. We elucidate our preparation scheme using the language of tensor networks, and furthermore show that the $\mathbb{Z}_2\times\mathbb{Z}_2$ symmetry of the AKLT state directly affords this speed-up over previously known preparation methods. To demonstrate the practical advantage of measurement-assisted preparation on noisy intermediate-scale quantum (NISQ) devices, we carry out our protocol on an IBM Quantum processor. We measure both the string order and entanglement spectrum of prepared AKLT chains and, employing these as metrics, find improved results over the known (purely unitary) sequential preparation approach. We conclude with a demonstration of quantum teleportation using the AKLT state prepared by our measurement-assisted scheme. This work thus serves to provide an efficient strategy to prepare a specific resource in the form of the AKLT state and, more broadly, experimentally demonstrates the possibility for realizable improvement in state preparation afforded by measurement-based circuit depth reduction strategies on NISQ-era devices.Comment: 17 pages, 8 figures. Supplemental Material: 13 pages, 11 figure

Apertured Waveguides for Electromagnetic Wave Transmission

In some embodiments, an apertured waveguide includes a wall comprising a plurality of apertures and an interior channel along which electromagnetic waves can propagate, the interior channel being defined at least in part by the wall

Leveraging Hamiltonian Simulation Techniques to Compile Operations on Bosonic Devices

Circuit QED enables the combined use of qubits and oscillator modes. Despite a variety of available gate sets, many hybrid qubit-boson (i.e., oscillator) operations are realizable only through optimal control theory (OCT) which is oftentimes intractable and uninterpretable. We introduce an analytic approach with rigorously proven error bounds for realizing specific classes of operations via two matrix product formulas commonly used in Hamiltonian simulation, the Lie--Trotter and Baker--Campbell--Hausdorff product formulas. We show how this technique can be used to realize a number of operations of interest, including polynomials of annihilation and creation operators, i.e., $a^p {a^\dagger}^q$ for integer $p, q$. We show examples of this paradigm including: obtaining universal control within a subspace of the entire Fock space of an oscillator, state preparation of a fixed photon number in the cavity, simulation of the Jaynes--Cummings Hamiltonian, simulation of the Hong-Ou-Mandel effect and more. This work demonstrates how techniques from Hamiltonian simulation can be applied to better control hybrid boson-qubit devices.Comment: 48 pages, 5 figure

Bosonic Qiskit

The practical benefits of hybrid quantum information processing hardware that contains continuous-variable objects (bosonic modes such as mechanical or electromagnetic oscillators) in addition to traditional (discrete-variable) qubits have recently been demonstrated by experiments with bosonic codes that reach the break-even point for quantum error correction and by efficient Gaussian boson sampling simulation of the Franck-Condon spectra of triatomic molecules that is well beyond the capabilities of current qubit-only hardware. The goal of this Co-design Center for Quantum Advantage (C2QA) project is to develop an instruction set architecture (ISA) for hybrid qubit/bosonic mode systems that contains an inventory of the fundamental operations and measurements that are possible in such hardware. The corresponding abstract machine model (AMM) would also contain a description of the appropriate error models associated with the gates, measurements and time evolution of the hardware. This information has been implemented as an extension of Qiskit. Qiskit is an opensource software development toolkit (SDK) for simulating the quantum state of a quantum circuit on a system with Python 3.7+ and for running the same circuits on prototype hardware within the IBM Quantum Lab. We introduce the Bosonic Qiskit software to enable the simulation of hybrid qubit/bosonic systems using the existing Qiskit software development kit. This implementation can be used for simulating new hybrid systems, verifying proposed physical systems, and modeling systems larger than can currently be constructed. We also cover tutorials and example use cases included within the software to study Jaynes- Cummings models, bosonic Hubbard models, plotting Wigner functions and animations, and calculating maximum likelihood estimations using Wigner functions