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Ultrafast Phenomena and Nanophotonics XXIX 2025

作者： Khanmohammadi, Sepideh Williams, Camille Friedman, Kateryna Kushnir Grimm, Ronald L. Koski, Kristie J. Titova, Lyubov V. Department of Physics Worcester Polytechnic Institute WorcesterMA01609 United States Department of Chemistry and Biochemistry Worcester Polytechnic Institute WorcesterMA01609 United States Department of Chemistry University of California Davis DavisCA95616 United States

ISBN: (纸本)9781510684768

SnS2 is a two-dimensional (2D) layered semiconductor with a visible-range bandgap (~2.3 eV), high charge carrier mobility, long carrier lifetimes, and good environmental stability. This study explores the impact of zero-valent metal intercalation into the van der Waals gaps of SnS2 on charge carrier dynamics. We demonstrate that metal intercalation enhances optical absorption in the yellow-to-IR range and induces metal-dependent bandgap shifts. Time-resolved THz spectroscopy reveals that different metals uniquely influence photoconductivity dynamics: We find that intercalation with Bi, Ni, and Fe shortens the photoconductivity decay times, whereas Rh intercalation results in a slower decay. These findings highlight the potential of metal intercalation to tailor SnS2 properties for diverse applications, from solar energy conversion to high-speed photodetectors. © 2025 SPIE.

关键词： Layered semiconductors

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Development of a low-cost volumetric moisture content sensor at 76 GHz for industrial drying applications using effective medium modeling

Development of a low-cost volumetric moisture content sensor...

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Sensors and Communication Technologies in the 1 GHz to 10 THz Band 2024

作者： Bouchard, Jacob N. Petkie, Douglas T. Department of Physics Worcester Polytechnic Institute WorcesterMA United States NRC United States Naval Research Laboratory WashingtonDC United States

ISBN: (数字)9781510681156

ISBN: (纸本)9781510681149

Current methods of production line compatible moisture content detection are too costly to allow for full process monitoring. Other key drawbacks of current methods include sensitivity to changes in sample color, poor sample penetration, and limited moisture content measurement range. Sensors operating in the THz range could provide a solution to these problems and by carefully picking the frequency, a low-cost sensor could be developed. This work covers the development of a low-cost volumetric moisture content sensor based on commercial off-the-shelf hardware, a TI IWR1642 76 GHz automotive radar module, coupled with a sample specific calibration based on effective medium theory. The resulting sensor is orders of magnitude less expensive than competing sensors while providing measurements of volumetric moisture content accurate to within 5% dry-basis moisture content. This work includes a study of two effective medium models, the Bruggeman method and the Looyenga method, and their applicability to the moisture sensing problem as well as a detailed description of the methodology used to build these models and assess their accuracy. These effective medium models utilize known microscopic material properties to describe the macroscopic properties of mixtures. The application space that this study explored was industrial pulp and paper production where precise measurement and fast measurement of volumetric water content is crucial for ensuring product quality and consistency. Using electromagnetic radiation in the THz band to measure the water content of paper is not completely novel but previous approaches have made use of empirical calibration models which require significant time to acquire and can be sensitive to changes in calibration and application environment. © 2024 SPIE.

关键词： Calibration

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Creating a Framework for Non-Profit Impact Reporting

Creating a Framework for Non-Profit Impact Reporting

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Annual IEEE Systems Conference

作者： Parker Langa Mona Blake Sarah Fenton Michael Nixdorf Shamsnaz V. Bhada Electrical and Computer Engineering Worcester Polytechnic Institute Worcester MA Mechanical Engineering Worcester Polytechnic Institute Worcester MA Chemical Engineering Worcester Polytechnic Institute Worcester MA Theoretical Physics Worcester Polytechnic Institute Worcester MA

ISBN: (数字)9798331508180

ISBN: (纸本)9798331508197

Non-profit organizations are increasingly pressured to provide impact analysis highlighting their community influence to continue receiving financial support. Organizations with limited resources can struggle in areas such as data organization, visualization, and conflicting stakeholders' expertise and interest. The need to show evidence-based impact while struggling with resources is a balancing act of survival for many non-profits and a unique case of a Socio-Technical system. In our research, we attempt to tackle this Socio-Technical problem by creating a framework and building tools to alleviate this balancing act to allow non-profits to devote their resources to supporting their mission. We use a mixed methods approach through data collection and analysis to provide a cohesive overview of a charity's influence while requiring few resources. We apply this method to Historic Buildings & Places (HB&P), a non-profit organization in the UK that works to preserve built heritage to retain its cultural value and increase sustainable infrastructure. Using HB&P as a case study provides an understanding of practices used to complete this mixed methods approach. This paper describes the process for determining impact criteria and creating an accessible report as well as providing a set of terms and a procedure applicable to non-profits across many sectors. The findings include which graphics wider audiences easily understand—column graphs and maps—and which themes are currently sought after—diversity and sustainability. Given our interview pool focused on current and potential stakeholders, non-profits who focus on highlighting their diversity and sustainability work through accessible graphics have the potential to increase their financial support.

关键词： Sociotechnical systems Visualization Data analysis Buildings Software Stakeholders Sustainable development Interviews Heat maps Lenses

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MXene Property Prediction via Graph Contrastive Learning

MXene Property Prediction via Graph Contrastive Learning

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International Conference on Nanomaterials: Application & Properties (NAP)

作者： Eric Warnemunde Vertina Emily Sutherland N. Aaron Deskins Oren Mangoubi Data Science Worcester Polytechnic Institute Worcester MA USA Physics Worcester Polytechnic Institute Worcester MA USA Chemical Engineering Worcester Polytechnic Institute Worcester MA USA

ISBN: (数字)9798350380125

ISBN: (纸本)9798350380132

MXenes are an important class of 2-D materials with expected novel properties and myriad applications, including efficient energy conversion in batteries and solar cells, environmental and water treatment, supercapacitors, electromagnetic interference shielding, and catalysts. Unfortunately, MXenes are challenging to synthesize in the laboratory, and numerical models for simulating MXene properties, such as density functional theory (DFT), remain computationally expensive. For this reason, multiple prior works develop machine learning (ML) methods to rapidly predict MXene properties. However, these methods do not take into account the graphical structure of the MXene’s molecular bonds, reducing their accuracy. In this work, we introduce a novel ML method, based on Graph Neural Networks (GNNs), which includes MXene molecular graph information to predict electrical and physical properties. Our method transforms graph datasets to lower-dimensional embedding spaces with graph contrastive learning (GCL), a type of GNN, enabling high-accuracy predictions for downstream models trained with these embeddings. Our method obtains the following root mean square errors (RMSEs) when predicting properties from a DFT-based MXenes dataset (including many MXene properties not previously predicted with deep learning models): 0.418 J for Work Function, $0.518 \mathrm{eV}^{-1}$ for Density of States at Fermi Level, $\mathbf{0. 0 6 7}$ for Poisson’s Ratio, $21.65 \mathrm{~N} / \mathrm{m}$ for Bulk Modulus, 14.56 N/m for Shear Modulus, 35.66 N/m for Young’s Modulus, and 82% accuracy for Magnetic (T/F). Our method obtains lower mean absolute error (MAE) when predicting four target properties from the molecular QM9 dataset compared to a similar-complexity baseline. Predicting MXene properties more accurately, efficiently, and effectively promises to better enable MXene commercialization.

关键词： Water Accuracy Photovoltaic cells Contrastive learning Transforms Predictive models Supercapacitors Graph neural networks Root mean square Magnetic properties

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Creating a Framework for Non-Profit Impact Reporting 19

Creating a Framework for Non-Profit Impact Reporting

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19th Annual IEEE International Systems Conference, SysCon 2025

作者： Langa, Parker Blake, Mona Fenton, Sarah Nixdorf, Michael Bhada, Shamsnaz V. Worcester Polytechnic Institute Electrical and Computer Engineering WorcesterMA United States Worcester Polytechnic Institute Mechanical Engineering WorcesterMA United States Worcester Polytechnic Institute Chemical Engineering WorcesterMA United States Worcester Polytechnic Institute Theoretical Physics WorcesterMA United States

ISBN: (纸本)9798331508180

Non-profit organizations are increasingly pressured to provide impact analysis highlighting their community influence to continue receiving financial support. Organizations with limited resources can struggle in areas such as data organization, visualization, and conflicting stakeholders' expertise and interest. The need to show evidence-based impact while struggling with resources is a balancing act of survival for many non-profits and a unique case of a Socio-Technical system. In our research, we attempt to tackle this Socio-Technical problem by creating a framework and building tools to alleviate this balancing act to allow non-profits to devote their resources to supporting their mission. We use a mixed methods approach through data collection and analysis to provide a cohesive overview of a charity's influence while requiring few resources. We apply this method to Historic Buildings & Places (HB&P), a non-profit organization in the UK that works to preserve built heritage to retain its cultural value and increase sustainable infrastructure. Using HB&P as a case study provides an understanding of practices used to complete this mixed methods approach. This paper describes the process for determining impact criteria and creating an accessible report as well as providing a set of terms and a procedure applicable to non-profits across many sectors. The findings include which graphics wider audiences easily understand - column graphs and maps - and which themes are currently sought after - diversity and sustainability. Given our interview pool focused on current and potential stakeholders, non-profits who focus on highlighting their diversity and sustainability work through accessible graphics have the potential to increase their financial support. © 2025 IEEE.

关键词： Nonprofit organization

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Modelling the Impact of Quantum Circuit Imperfections on Networks and Computer Applications

arXiv

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arXiv 2024年

作者： Glisic, Savo Department of Physics Worcester Polytechnic Institute WorcesterMA United States

Post‐Quantum (q-) and Quantum Cryptography schemes (sch’s) are feasible q-computer applications for 7G networks. These sch ‘s could possibly replace RSA and ECC sch ‘s. These algorithms have been compromised by advances in quantum search algorithms run on quantum computers like Shor’s algorithm. Shor's algorithm is a quantum algorithm for finding the prime factors of an integer which is the basis of RSA algorithm. This has become an available quantum computer application putting the use of RSA algorithm at risk. Our recent paper provides a detailed survey of the work on post‐quantum (q-) and q-cryptography (Cry) algorithms (alg’s) with focus on their applicability in 7G networks (net’s). Since the paper focuses on the cryptography algorithms (alg’s) as a follow up, in this paper, we provide a new framework for quantum network optimization and survey in detail the work on enabling technologies (q-hardware) for the practical implementation of these alg’s including the most important segments of quantum hardware (hrdw) in 7G. As always in engineering practice practical solutions are a compromise between the performance and complexity/cost of the implementation. For this reason, as the main contribution, the paper presents a network and computer applications optimization framework that includes implementation imperfections. The tools should be useful in optimizing future generation practical computer system design. After that a comprehensive survey of the existing work on quantum hardware is presented pointing out the sources of these imperfections. This enables us to make a fair assessment of how much investment into quantum hardware improvements contributes to the performance enhancement of the overall system. In this way a decision can be made on proper partitioning between the investment in hardware and system level complexity. The paper is organized as follows: In Section II we start by presenting a q-network optimization framework that includes implementation impe

关键词： Quantum cryptography

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Ultrafast carrier dynamics in 2D GeS in response to photoexcitation across the visible-NIR range 27

Ultrafast carrier dynamics in 2D GeS in response to photoexc...

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Ultrafast Phenomena and Nanophotonics XXVII 2023

作者： Khanmohammadi, Sepideh Tran, Catherine Colin-Ulloa, Erika Kushnir, Kateryna Koski, Kristie J. Titova, Lyubov V. Department of Physics Worcester Polytechnic Institute WorcesterMA01609 United States Department of Chemistry University of California Davis DavisCA95616 United States

ISBN: (纸本)9781510659438

Germanium sulfide (GeS) is a 2D semiconductor with high carrier mobility, a moderate band gap of about 1.6 eV, and highly anisotropic optical properties. In-plane anisotropy and a large in-plane spontaneous electric polarization in GeS monolayers have been predicted to result in significant second order nonlinear effects in response to above-the-gap excitation with photon energy > 2.5 eV1. We have further confirmed it experimentally by demonstrating surface shift current generation in GeS using THz emission spectroscopy with 3.1 eV excitation.3 Here, we use time-resolved THz spectroscopy to investigate the dynamics and lifetimes of photoexcited carriers in GeS single crystals and nanoribbons in response to excitations with energies ranging from 1.5 eV, resonant with the bulk gap, to 3.1 eV. We find that resulting dynamics vary considerably. Lower energy (1.5 eV) excitation injects carriers directly into three low-lying valleys in the conduction band. Those carriers have long, which photoconductivity persisting for over 500 ps, as it can be seen in Fig. 1(a). On the other hand, injecting carriers high into the conduction band results in THz emission due to the shift current as well as into transient photoconductivity that recovers over © 2023 SPIE.

关键词： Sulfur compounds

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Lessons on mobile apps for COVID-19 from China

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Journal of Safety Science and Resilience 2021年第2期2卷 40-49页

作者： Sophia L.Zhou Xianhan Jia Samuel P.Skinner William Yang Isabelle Claude Mass Academy of Math and Science Worcester Polytechnic Institute85 Prescott StreetWorcesterMA 01605United States Department of Computer Science Worcester Polytechnic Institute100 Institute RoadWorcesterMA 01609United States Department of Physics Worcester Polythenic Institute100 Institute RoadWorcesterMA 01609United States Department of Biomedical Engineering Worcester Polytechnic Institute100 Institute RoadWorcesterMA 10609United States

The COVID-19 pandemic has impacted the global society and human life *** countries have launched COVID-19 mobile apps with a wide range in how these apps *** it is hoped that these apps can assist in the fight against COVID-19,many are worried about user *** implemented“health code”systems,which assigned neighborhoods and citizens a specific health code,meant to indicate their risk of having been exposed to *** most widely used health code systems were hosted on the popular apps WeChat and Alipay,each with billions of *** experts argued that China’s use of mobile applications was essential to its successful combat against *** in this study are a summary of mobile technology usage in China,a review of previous studies of mobile technology in healthcare,and a brief survey of some existing mobile applications for COVID-19 that were *** included are outcomes of interviews with healthcare and public safety experts and a public survey to understand how mobile applications were used in China’s response to *** interviews revealed four important themes:personal privacy,community involvement,government involvement,and situational *** was found that a key concern was maintaining a balance between collecting and utilizing personal information,as well as protecting this *** addition,close collaboration between local communities and the national government was *** applications assisted in communication and coordination but did not replace the work of people such as delivery drivers and contact *** results also showed that there was room for improvement,especially accessibility for the elderly or those unfamiliar with *** results were obtained from our *** was interesting to find that the apps were mostly used for“accessing information on COVID-19.”In addition,respondents overwhelmingly identified“information”as the most valuable featur

关键词： Mobile apps COVID-19 response Survey Interview Lessons

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Quantitative Interpretation of Simulated Polymer Mean-Square Displacements

arXiv

引用

arXiv 2024年

作者： Phillies, George D.J. Department of Physics Worcester Polytechnic Institute WorcesterMA01609 United States

We propose a path for making quantitative analyses of mean-square displacement curves of polymer chains in the melt or in solution. The approach invokes a general functional form that accurately describes g(t) ≡ 〈(∆x(t))2〉 for all times at which g(t) was measured, and that gives values for the logarithmic derivative of g(t) for the same times. By these means we can readily distinguish between regimes in which g(t) follows a power law in time, does not follow a power law in time, or has an inflection point. In a power-law regime, the method accurately determines the exponent, without imposing any assumption as to the exponent's value. © 2024, CC BY.

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Diffusing Wave Microrheology in Polymeric Fluids

arXiv

引用

arXiv 2024年

作者： Phillies, George D.J. Department of Physics Worcester Polytechnic Institute WorcesterMA01609 United States

Recently, there has been interest in determining the viscoelastic properties of polymeric liquids and other complex fluids by means of Diffusing Wave Spectroscopy (DWS). In this technique, light-scattering spectroscopy is applied to highly turbid fluids containing optical probe particles. The DWS spectrum is used to infer the time-dependent mean-square displacement and time-dependent diffusion coefficient D of the probes. From D, values for the storage modulus G′(ω) and the loss modulus G′′(ω) are obtained. This paper is primarily concerned with the inference of the mean-square displacement from a DWS spectrum. However, in much of the literature, central to the inference that is said to yield D is an invocation g(1)(t) = exp(−2q2X(t)2) of the Gaussian Approximation for the field correlation function g(1)(t) of the scattered light in terms of the mean-square displacement X(t)2 of a probe particle during time t. Experiment and simulation both show that the Gaussian approximation is invalid for probes in polymeric liquids and other complex fluids. In this paper, we obtain corrections to the Gaussian approximation that will assist in interpreting DWS spectra of probes in polymeric liquids. The corrections reveal that these DWS spectra receive contributions from higher moments X(t)2n, n > 1, of the probe displacement distribution function. © 2024, CC BY.

关键词： Probes

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