Accurate Acoustic 2D Mapping Apparatus

ME450 Capstone Design and Manufacturing Experience: Fall 2020Prof. Popa's lab has an acoustic mapping chamber used in his experiments on metamaterials. The current microphone positioning system interferes with data collection. The purpose of this project was to develop a positioning system that acts without direct connection to the interior of the chamber. Our design process resulted in a magnetically positioned interior housing that can easily interface with the existing setup. Pandemic restrictions and time constraints prevented us from completing a prototype housing, but our empirical testing of a simple mockup did show promising results.Prof. Bogdan Popa, U-M Mechanical Engineering - Popa Research Grouphttp://deepblue.lib.umich.edu/bitstream/2027.42/164451/1/Accurate_Acoustic_2D_Mapping_Apparatus.pd

Beneficial Use Of C&D Recovered Screen Material In Residential Applications: A Case Study

Florida has established guidelines to encourage recycling and use of recycled materials in a manner protecting public health and the environment. Recovered screened material (RSM) generated at a construction and demolition (C&D) debris recovery facility is a recycled material with reuse potential. In order to reuse RSM, it must be shown that the material poses no significant threat to public health or the environment. The Sun Recycling facilities in Broward and Palm Beach counties are C&D facilities, generating RSM (i.e., soil with wood, concrete, other C&D particles) through mechanical separation using screens. The process generates RSM meeting state requirements for industrial, commercial, and residential use. RSM was used on residential lots in Miramar to elevate low areas (excluding building pads). In accord with Broward County Environmental Protection Department (EPD) and Palm Beach County Department of Health (DOH) permits, Sun facilities perform regular testing of RSM. RSM tests showed arsenic (As) concentrations below state criteria. Quarterly testing did not detect VOCs, SVOCs, or pesticides. RSM was delivered to homesites and mixed with existing site soil. To address concerns raised by some residents, Miramar hired a consultant to collect samples for arsenic and total recoverable petroleum hydrocarbons (TRPH), resulting in reports of some As levels above residential criteria. Further sampling/analysis of RSM and local soils in the neighborhood were performed by Broward EPD and Sun. Results of As and speciated TRPH analysis performed by the Miramar, Broward EPD, and Sun will be discussed. A consensus conclusion of acceptable conditions was reached by all parties

International approaches to protecting and retaining trees on private urban land

Most studies of urban forest management look at vegetation on public land. Yet, to meet ambitious urban forest targets, cities must attempt to maintain or increase trees and canopy cover on private urban land too. In this study, we review and evaluate international approaches to protecting and retaining trees on private urban land. Our study combines a systematic academic literature review, two empirical social science studies on the views of urban forest professionals, and a global case study review of innovative regulations and incentives aimed at protecting and retaining trees on private urban land. Case studies were evaluated for the extent they exceeded minimum standards or went beyond ?business-as-usual?. We found that the most innovative mechanisms combine many regulations, instead of relying on a single regulation, and use financial incentives to retain or plant trees in newly developed or re-developed sites, as well as private residences. We did not find any cases where appropriate monitoring was in place to determine the efficacy and efficiency of these mechanisms. We also found no single simple solution that could effectively and efficiently protect and retain trees on private land. Only by combining policies, planning schemes, local laws, and financial incentives with community engagement and stewardship will cities protect and retain trees on private land. Useful and innovative ways to protecting and retaining trees on private land involves providing solutions at multiple governments levels, embedding trees in existing strategic policy and management solutions, incentivising positive behavior, creating regulations that require payment up front, and engaging the broader community in private tree stewardship.Peer reviewe

Design and Prototyping of a Nanosatellite Laser Communications Terminal for the Cubesat Laser Infrared CrosslinK (CLICK) B/C Mission

The CubeSat Laser Infrared CrossLink (CLICK) mission goal is to demonstrate a low cost, high data rate optical transceiver terminal with fine pointing and precision time transfer in aleq1.5U form factor. There are two phases to the technology demonstration for the CLICK mission: CLICK-A downlink, and then CLICK-B/C crosslink and downlink. The topic of this paper is the design and prototyping of the laser communications (lasercom) terminal for the CLICK-B/C phase. CLICK B/C consists of two identical 3U CubeSats from Blue Canyon Technologies that will be launched together in Low Earth Orbit to demonstrate crosslinks at ranges between 25 km and 580 km with a data rate of ≥20 Mbps and a ranging capability better than 0.5 m. Downlinks with data rates of ≥10 Mbps will also be demonstrated to the Portable Telescope for Lasercom (PorTeL) ground station. Link analysis using current parameters & experimental results predicts successful crosslink & downlink communications and ranging. Moreover, closed-loop 3σ fine pointing error is predicted to be less than 39.66 μrad of the 121.0 μrad 1/e² transmit laser divergence. The status of the payload EDU and recent developments of the optomechanical and thermal designs are discussed

CLICK-A: Optical Communication Experiments From a CubeSat Downlink Terminal

The CubeSat Laser Infrared CrosslinK (CLICK) mission is a technology demonstration of low size, weight, and power (SWaP) CubeSat optical communication terminals for downlink and crosslinks. The mission is broken into two phases: CLICK-A, which consists of a downlink terminal hosted in a 3U CubeSat, and CLICK-B/C, which consists of a pair of crosslink terminals each hosted in their own 3U CubeSat. This work focuses on the CLICK-A 1.2U downlink terminal, whose goal was to establish a 10 Mbps link to a low-cost portable 28 cm optical ground station called PorTeL. The terminal communicates with M-ary pulse position modulation (PPM) at 1550 nm using a 200 mW Erbium-doped fiber amplifier (EDFA) with a 1.3 mrad FWHM beam divergence. CLICK-A ultimately serves as a risk reduction phase for the CLICK-B/C terminals, with many components first being demonstrated on CLICK-A. CLICK-A was launched to the International Space Station on July 15th, 2022 and was deployed by Nanoracks on September 6th, 2022 into a 51.6° 414 km orbit. We present the results of experiments performed by the mission with the optical ground station located at MIT Wallace Astrophysical Observatory in Westford, MA. Successful acquisition of an Earth to space 5 mrad FWHM (5 Watts at 976 nm) pointing beacon was demonstrated by the terminal on the second experiment on November 2nd, 2022. First light on the optical ground station tracking camera was established on the third experiment on November 10th, 2022. The optical ground station showed sufficient open, coarse, and fine tracking performance to support links with the terminal with a closed-loop RMS tracking error of 0.053 mrad. Results of three optical downlink experiments that produced beacon tracking results are discussed. These experiments demonstrated that the internal microelectromechanical system (MEMS) fine steering mirror (FSM) corrected for an average blind spacecraft pointing error of 8.494 mrad and maintained an average RMS pointing error of 0.175 mrad after initial blind pointing error correction. With these results, the terminal demonstrated the ability to achieve sufficient fine pointing of the 1.3 mrad FWHM optical communication beam without pointing feedback from the terminal to improve the nominal spacecraft pointing. Spacecraft drag reduction maneuvers were used to extend mission life and inform the mission operations of the CLICK-B/C phase of the mission. Results from the spacecraft drag maneuvers are also presented

Development of CubeSat Spacecraft-to-Spacecraft Optical Link Detection Chain for the CLICK B/C Mission

The growing interest in and expanding applications of small satellite constellation networks necessitates effective and reliable high-bandwidth communication between spacecraft. The applications of these constellations (such as navigation or imaging) rely on the precise measurement of timing offset between the spacecraft in the constellation. The CubeSat Laser Infrared CrosslinK (CLICK) mission is being developed by the Massachusetts Institute of Technology (MIT), the University of Florida (UF), and NASA Ames Research Center. The second phase of the mission (CLICK-B/C) will demonstrate a crosslink between two CubeSats (B and C) that each host a \u3c 2U laser communication payload. The terminals will demonstrate full-duplex spacecraft-to-spacecraft communications and ranging capability using commercial components. As part of the mission, CLICK will demonstrate two-way time-transfer for clock synchronization and data transfer at a minimum rate of 20 Mbps over separation distances ranging from 25 km to 580 km. The payloads of CLICK B and C include a receiver chain with a custom photodetector board, a Time-to-Digital Converter (TDC), a Microchip Chip-Scale Atomic Clock (CSAC), and a field-programmable gate array (FPGA). The payloads can measure internal propagation delays of the transmitter and the receiver, and cancel environmental effects impacting timing accuracy. The photodetector board is 2.5 cm x 2.5 cm and includes an avalanche photodiode (APD) and variable-gain amplifiers through which the detected signal is conditioned for the TDC to be time-stamped. This design has been developed from the UF and NASA Ames CubeSat Handling Of Multisystem Precision Time Transfer (CHOMPTT) project and associated MOCT (Miniature Optical Communication Transceiver) demonstration. The TDC samples the signal at four points: twice on the rising edge at set thresholds, and twice at the falling edge at those same thresholds. These four time-offset samples are sent to the FPGA, which combines the measurements for a reported timestamp of the detected laser pulse. These timestamps can then be used in a pulse-position modulation (PPM) demodulation scheme to receive data at up to 50 Mbps, to calculate range down to 10 cm, and for precision time-transfer with \u3c 200 ps resolution. In this paper, we will discuss the designed capabilities and noise performance of the CLICK TDC-based optical receiver chain

Investigating the relationship between competence and patient outcome with CBT

Little is understood about the relationship between therapist competence and the outcome of patients treated for common mental health disorders. Understanding the relationship between competence and patient outcome is of fundamental importance to the dissemination and implementation of Cognitive Behavioural Therapy (CBT). The current study extends existing literature by exploring the relationship between CBT competence and patient outcome in routine clinical practice within the framework of the British Government’s Improving Access to Psychological Therapies (IAPT) programme. Participants comprised 43 therapists treating 1247 patients over a training period of one year. Results found little support of a general association between CBT competence and patient outcome; however significantly more patients of the most competent therapists demonstrated a reliable improvement in their symptoms of anxiety than would be expected by chance alone, and fewer experienced no reliable change. Conversely, significantly more patients treated by the least competent therapists experienced a reliable deterioration in their symptoms than would be expected. The implications of these results for the dissemination and implementation of CBT are discussed

Development and Results of a Lasercom Testbed for the CLICK B/C CubeSats and Future Missions

The expansion of interest in small satellite constellation networks underscores the need for precise timing synchronization and reliable high-bandwidth communication between spacecraft. The CubeSat Laser Infrared CrosslinK (CLICK) mission is being developed by the Massachusetts Institute of Technology, the University of Florida, and NASA Ames Research Center. The first phase of the mission, CLICK A, was launched on July 14, 2022, aboard SpaceX’s CRS-25 and put into orbit from the International Space Station, where it successfully demonstrated the downlink to Earth. The second phase of the mission (CLICK B/C) will additionally demonstrate a crosslink between two 3U CubeSats (B and C) that each host a 1.5 U laser communication payload. The terminals will demonstrate full-duplex spacecraft-to-spacecraft communications and ranging capability using commercial-off-the-shelf components at low size, weight and power (SWaP). As part of the mission, CLICK will demonstrate two-way time transfer for chip-scale atomic clock (CSAC) synchronization and data transfer. This data transfer will use pulse-position modulation (PPM) at rates between 20 Mbps and 50 Mbps over separation distances ranging from 25 km to 580 km. A time-transfer precision of \u3c 200 ps between the spacecraft is targeted. CLICK B/C is scheduled to launch in 2025. The University of Florida hosts a testbed to support CLICK developments. Its goal is to enable testing of the optical data- and timing-transfer chain on ground. This encompasses the vital components of the CLICK hardware for both TX (transmission) and RX (receiving). For TX, the electronics and laser system to generate optical pulses are included, with the latter consisting of a micro-integrable tunable laser assembly as seed laser and a semiconductor optical amplifier as shutter. In turn, the RX side consists of an avalanche photodetector (APD) to capture the pulses, electronics to condition and convert the analog signal into the digital domain (time-to-digital and analog-to-digital), and a field-programmable gate array as DSP (digital signal processing) platform. The DSP implements the algorithm to decode the PPM scheme and extract timing information. In between the optical TX and RX, an electrical variable optical gain amplifier is placed to simulate varying distances between satellites and the associated change in received power. The final setup is envisioned to use separate hardware platforms for TX and RX to test the timing transfer between independent CSACs. Here we present the status of the testbed and the associated development of CLICK hardware and DSP, in particular the APD and PPM decoder, along with results of the lasercom testing, showing initial tracking of test data