Dartmouth Institute for Health Policy and Clinical Practice
Dartmouth Digital Commons (Dartmouth College)Not a member yet
8214 research outputs found
Sort by
Mahjouba Initiative eBike Charging in Morocco
No full textThe Mahjouba Initiative, led by artist Eric van Hove, merges Moroccan craftsmanship with modern engineering to develop locally sourced, sustainably produced e-bikes for rural communities. A team from Dartmouth College’s ENGS 90 conducted a feasibility analysis of a scalable, affordable e-bike charging station for deployment in Tissint, Tata, Morocco, where transportation infrastructure limitations hinder economic development. This analysis supports a battery-swapping pilot as a crucial step in advancing the Mahjouba Initiative’s mission to develop domestically powered transportation. The proposed charging station includes on-grid and off-grid (solar-powered) options, ensuring flexible deployment based on available energy infrastructure. Key design considerations include charging efficacy, user accessibility, and implementation viability. A techno-economic analysis compares internal combustion engine bikes with electric bikes, evaluating fuel savings, lifecycle costs, and financial feasibility for both for-profit and non-profit models. Safety measures include manual and automatic error management, battery verification, and technician protocols. The team developed electrical and mechanical blueprints prioritizing replicability for local stakeholders. Additionally, policy and economic feasibility studies assessed scalability and regulatory challenges. Future research directions include thermal regulation for safe charging, tracking policy changes that may permit solar stations to sell excess energy, and improving system automation and safety. This project initiates the development of a viable, scalable pilot model, enabling the Mahjouba Initiative to expand e-bike adoption in Morocco’s rural regions, ultimately fostering sustainable mobility
Wheel Slip Detection for an Electric Racecar
No full textThis project developed a reliable wheel slip detection system for Dartmouth Formula Racing\u27s (DFR) electric racecar, the first step for implementing traction control. The existing wheel speed sensors on DFR\u27s vehicle ( Cherri ) were not producing reliable or readable data. This limits the team\u27s ability to implement effective traction control. Our solution includes a comprehensive hardware and software package that accurately measures, filters, and processes wheel speed data to calculate slip ratio - a key parameter for implementing traction control. The system utilizes high-resolution rotary encoders mounted on the front wheels that sample at 5-20ms intervals, runs hardware based quadrature decoders to process encoder signals, and infinite impulse response (IIR) filters to reduce noise. This data, along with rear wheel speed measurements from the vehicle\u27s motor inverter, is transmitted over the car\u27s Central Area Network (CAN) bus to the Central Vehicle Controller (CVC), where the slip ratio is calculated in real-time. Through extensive testing and validation, we demonstrated the system\u27s ability to detect slip ratios as low as 1% and maintain wheel speed measurements within 5% of ground truth across the vehicle\u27s full operating range, including top speeds of approximately 120 MPH. The project also delivered comprehensive documentation, a new front sensor board schematic, and training materials to ensure knowledge transfer to future DFR team members. This wheel slip detection system provides the foundation for future traction control implementations that will enhance the vehicle\u27s acceleration performance, improve energy efficiency, and increase safety by preventing loss of traction during competitive driving scenarios
Characterization and evaluation of next-generation photon-counting image sensors for space applications
No full textAstronomers’ pursuit of imaging light from increasingly faint and distant objects in the expanse of space necessitates continuous improvement in the signal-to-noise ratio of camera technology. Recent advancements in solid-state detector technologies have enabled the determination of photon number, including single-photon events, enabling observations at the fundamental limits of physics. We present an evaluation of three next-generation silicon-based detectors capable of photon-counting with deep-sub-electron input-referred read noise: the electron-multiplying charge-coupled device (EMCCD), the single-photon avalanche diode (SPAD), and the CMOS quanta image sensor (QIS). The EMCCD is built using a CCD sensor design that additionally employs repeated impact ionization to amplify the signal during readout, thereby reducing input-referred readout noise to deep-sub-electron levels and facilitating single-photon counting. SPAD devices utilize fast in-pixel signal amplification via impact ionization and positive feedback to achieve negligible effective read noise and precise time-of-arrival measurements of photons, enabling high-precision distance measurement and photon-counting. QIS devices take a distinct approach by utilizing a CMOS pixel topology that increases conversion gain without the need for impact ionization, thereby reducing readout noise to deep-sub-electron levels and enabling photon-number resolution, high dynamic range, and high spatial resolution. Characteristics of a representative device from each technology are evaluated with an emphasis on suitability for space flight missions. Furthermore, a summary analysis of emerging CCD and CMOS image sensors with “Skipper” readout for photon-number-resolving applications is also discussed in this report
A Trigger for the Autonomous Decommissioning of Smart Devices
No full textSmart devices are ubiquitous in modern environments, yet their decommissioning phase remains poorly studied and often overlooked in system design. We define secure decommissioning as the process by which a smart device securely disconnects from its environment and makes sensitive data inaccessible. If not decommissioned, devices may retain sensitive information – such as security credentials or user-behavior data that could be recovered by an adversary. Unfortunately, some users may forget to decommission a device when they dispose or sell it, and cannot decommission a device that is lost or stolen. This paper investigates a trigger mechanism for individual wireless smart devices to automatically identify conditions requiring decommissioning. Our approach does not require any hardware changes to wireless devices. We evaluated it through extensive simulations and validated it on real IoT-class hardware. With appropriate parameter values, our mechanism always correctly identified when to decommission and never falsely decommissioned. These parameters can be tuned to user needs. Our work presents a baseline for locally triggered autonomous decommissioning, providing researchers with a useful starting point for exploring and improving alternative designs
3D MRI-GUIDED NEAR-INFRARED SPECTROSCOPIC TOMOGRAPHY FOR IMAGING BREAST CANCER
No full textWhile dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is widely recognized as the most sensitive modality for breast cancer detection, it has notable limitations, including a high false-positive rate and potential safety concerns associated with gadolinium (Gd) contrast agents. Consequently, there is growing interest in alternatives that rely on endogenous contrast. To address this need, the overall goal of this thesis is to develop and evaluate a concurrent MRI-guided near-infrared spectroscopic tomography (MRg-NIRST) platform capable of achieving reliable diagnostic performance without the use of contrast agents. In this multi-modality imaging approach, MRI provides high-resolution anatomical information about breast tissue composition, while NIRST offers quantitative hemodynamic and physiological biomarkers relevant to breast cancer detection.
In this thesis, a novel MRg-NIRST imaging system with an MRI-compatible, flexible breast optical interface was developed to provide functional tumor information based on physiologically relevant biomarkers. The system acquires optical data from up to 2,304 source-detector positions across the entire breast at six wavelengths (660–850 nm) simultaneously with MRI scans, in approximately four minutes, enabling 3D MRg-NIRST reconstruction of the entire breast. Furthermore, a new MRg-NIRST reconstruction method incorporating source-detector coupling was implemented to account for geometric variability across breast curvatures, reducing image artifacts and improving overall image quality.
The system was validated through a series of phantom studies, normal-subject imaging, and a clinical study involving breast cancer patients. Reconstructed images of heterogeneous phantoms demonstrated sharp contrast between inclusions and background, with accurate recovery of inclusion sizes. With the new Flexi-DRI reconstruction algorithm, the contrast-to-noise ratio (CNR) improved by up to 73% and the peak signal-to-noise ratio (PSNR) by up to 5.4%. Total hemoglobin (HbT) concentration values estimated from normal-subject images were consistent with those reported in previous optical imaging studies. Using MRg-NIRST, a breast cancer lesion measuring 5 × 6 × 9 mm was successfully detected in a heterogeneous dense breast. To our knowledge, this is the first demonstration that NIRST imaging can detect breast cancer lesions smaller than 10 mm, highlighting the potential of MRg-NIRST for early breast cancer detection in dense breast tissue
Poetry on the Mountain: Hiking Moosilauke in a Mood
Full text linkNear the summit of Mount Moosilauke, someone hands a hiker a copy of a Billy Collins poem with a typo.
Editor’s note: We have redacted the quoted lines of the Collins poem. Appalachia’s agreement to reprint part of “Night Letter to the Reader” covers only the print edition of the journal. Physical copies of this issue can be purchased at outdoors.org
Sacred Bodies and (A)historical Testimony: Han Kang\u27s Human Acts
Full text linkThe 1980 Gwangju Uprising is a significant event in contemporary South Korean political history. In the decades following, Gwangju literature has provided an avenue for representation, narrativization, and encounter with the event. South Korean author Han Kang is another writer of the Uprising, and her 2014 novel Human Acts returns to the site of injury in order to open up the event to the larger histories of sovereignty, civil conflict, and war that it localizes in Gwangju, 1980.
This thesis seeks to leverage the way the novel draws upon the sacred and the religious to call upon Gwangju. I argue that Human Acts accesses a non-sovereign sense of the sacred through ritual and literary testimony, ultimately disturbing sovereign history and time to create a vision of human dignity that persists after its destruction. This broadly occurs through a three-part process: first, the author takes on the role of shaman or spirit medium, initiating a plural ritual. These narrative rituals then facilitate literary testimony, effectively reenacting and repossessing the event of Gwangju. As testimony bridges the realms of before and after, sacred and profane, it retraces a topology of human dignity. Through testimony, the novel returns to the moment where dignity becomes visible—the moment of its destruction.
Somewhere within repeated ritual, Gwangju approaches what Walter Benjamin names the now-time in its chain of signification. As “omnipotent wound,” or repeated injury, Gwangju is not only excepted from the past but shot into the present, transfecting it. Following the original Korean title of the novel, 소년이 온다 (“The Boy Comes” or “The Boy Approaches”), Human Acts ultimately mobilizes the past. Through ritual, the novel constructs the memory of an absolute community—a momentary collective that has the potential to enter at any moment
