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The Truncated Cone Effect in AFM Nanoindentation on Soft Materials

Micro and Nanosystems 2023年第2期15卷 153-158页

作者： Kontomaris, Stylianos-Vasileios Malamou, Anna Department of Research and Development BioNanoTec LTD Nicosia Cyprus Faculty of Engineering and Architecture Metropolitan College Athens Greece Radar Systems and Remote Sensing Lab of the School of Electrical & Computer Engineering of National Technical University of Athens Athens Greece

Background: Atomic Force Microscopy (AFM) nanoindentation is the principal method for the characterization of soft materials at the nanoscale. In most cases, pyramidal tips are used and approximated to perfect cones. However, the extended use of the AFM tip may alter its sharp-ness. Objective: In many cases, a truncated cone shape is appropriate for tip modeling. In this technical note, the equation that relates the force with the indentation depth when indenting an elastic half-space using a truncated cone is derived. Methods: The nanoindentation equation for a truncated cone tip is derived using the fundamental differential equation that relates the sample’s contact stiffness with Young’s modulus. Results: When fitting Sneddon’s equation (which is valid for a perfect cone) on data obtained using a truncated cone-shaped AFM tip, the results show a ‘pseudo-softening’ behavior. Conclusion: The AFM tip's sharpness in nanoindentation experiments is a crucial parameter for obtaining the correct mechanical patterns of unknown samples. © 2023 Bentham Science Publishers.

关键词： Biological materials

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Smarter Horizontal Single Axis Tracking Using Optimal Positioning Algorithms 52

Smarter Horizontal Single Axis Tracking Using Optimal Positi...

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52nd IEEE Photovoltaic Specialist Conference, PVSC 2024

作者： Byford, Brandon Riley, Daniel Klipsch School of Electrical and Computer Engineering New Mexico State University Las CrucesNM88003 United States Sandia National Laboratories Photovoltaic Systems Evaluation Laboratory AlbuquerqueNM87123 United States

ISBN: (纸本)9781665464260

PV systems using horizontal single axis trackers (SATs) generate more energy than PV systems on fixed racking. The most common method of positioning a SAT minimizes the angle of incidence between the PV and the sun while avoiding row-to-row shading, thereby increasing energy production. Another approach, optimal position tracking, uses beyond sun position to attempt to capture the most irradiance possible under conditions where sun tracking is irrelevant (e.g., when a cloud obscures the sun). We present a study displaying the function of our SunDelay algorithm for optimal position tracking in Albuquerque, New Mexico and Eugene, Oregon. The SunDelay algorithm utilizes sun detection from sky imagery, location, and time data to position the panel optimally. The SunDelay algorithm tracks the sun naively throughout the day when the sun is not obscured. Once the sun is obscured in a series of sky images SunDelay makes a decision to either stay tracking naively or position the panel horizontally (towards zenith) to collect more diffuse irradiance. The SunDelay algorithm is compared against naive tracking through simulation, using data obtained from a Multi Planar Irradiance Sensor. The SunDelay algorithm collecting up to 0.2% and 4.7% more irradiance in NM and OR respectively over a month. © 2024 IEEE.

关键词： Solar irradiance

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Transaction Data Management Optimization Based on Multi-Partitioning in Blockchain systems 21

Transaction Data Management Optimization Based on Multi-Part...

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21st IEEE International Symposium on Parallel and Distributed Processing with Applications, 13th IEEE International Conference on Big Data and Cloud Computing, 16th IEEE International Conference on Social Computing and Networking and 13th International Conference on Sustainable Computing and Communications, ISPA/BDCloud/SocialCom/SustainCom 2023

作者： Zhang, Jingyu Hou, Xingxing Teng, Yilong Luo, Lailong Changsha University of Science and Technology School of Computer and Communication Engineering Changsha China National University of Defense Technology Science and Technology on Information Systems Engineering Laboratory School of Systems Engineering Changsha China

ISBN: (纸本)9798350329223

Unspent Transaction Output (UTXO) is part of the transaction data set, which represents the digital cryptocurrency asset in transaction-based blockchain systems. The data management capability, storage method and occupied space of UTXOs will greatly affect the running efficiency and the verification performance of blockchain systems. Especially, with the popularity of blockchain technology, the relevant UTXO data sets have been growing, and all the stored data can no longer be almost completely stored in memory. How should the UTXO transaction data be stored and managed at this time, it is an urgent issue to be solved in bitcoin-like blockchain systems. This paper provides a blockchain transaction data management optimization mechanism based on multi-partitioning. First, we analyze the influencing factors of transactions through real blockchain data. The proposed method can evaluate the time interval and transaction frequency factors, and use the received information to realize the efficient transaction data storage. In our design, UTXOs with lower likelihood to be used in new transactions will be stored in the disk, and the other UTXOs with higher likelihood to be used in new generated transactions should be stored in the cache. This approach aims to minimize memory consumption for the transaction data sets, accelerate UTXO access time during block verification, and ultimately decrease the overall time required for verification, leading to efficient UTXO transaction data management. Finally, the effectiveness of the proposed optimization mechanism is verified through theoretical analysis and simulation experiments, and the UXTO access time has been reduced compared with state-of-the-art methods. © 2023 IEEE.

关键词： Information management

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A High-Performance Data Verification Mechanism in Blockchain-Based IoT systems 21

A High-Performance Data Verification Mechanism in Blockchain...

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作者： Zhang, Jingyu Zhou, Pian Sun, Yongtao Luo, Lailong Changsha University of Science and Technology School of Computer and Communication Engineering Changsha China National University of Defense Technology Science and Technology on Information Systems Engineering Laboratory School of Systems Engineering Changsha China

ISBN: (纸本)9798350329223

With the rapid development of the distributed network and communication, the Internet of Things (IoT) systems have been applied to all walks of life. Blockchain technology is one of the most popular research fields recently, which can provide a reliable storage solution and solve information security issues for IoT systems. Transaction information is the most critical fundamental data in the blockchain systems, which needs to be verified to avoid being tempered with by malicious nodes in the process of transmission. With the exponential growth of the number of IoT devices, the limitations of the current storage structure put too much pressure on the system nodes. How to improve verification efficiency has become a key challenge. To alleviate this problem, this paper proposes a novel high-performance verification mechanism for data security protection in blockchain-based IoT systems. We design a new storage structure based on Huffman trunk tree (HTT), and conduct the quantitative analysis of transaction weights. Transactions are stored in full-featured devices in the form of Huffman Merkle tree (HMT), and only the content of HTT is saved in lightweight devices. Finally, the performance superiority of our mechanism is proved through theoretical analysis and experimental evaluation. In blockchain-based IoT systems, our mechanism significantly reduces the data transmission cost and computation overhead, effectively improving the efficiency of data verification. © 2023 IEEE.

关键词： Efficiency

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The Group Robustness is in the Details: Revisiting Finetuning under Spurious Correlations 38

The Group Robustness is in the Details: Revisiting Finetunin...

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38th Conference on Neural Information Processing systems, NeurIPS 2024

作者： LaBonte, Tyler Hill, John C. Zhang, Xinchen Muthukumar, Vidya Kumar, Abhishek H. Milton Stewart School of Industrial and Systems Engineering Georgia Institute of Technology United States School of Electrical and Computer Engineering Georgia Institute of Technology United States Google DeepMind United Kingdom

Modern machine learning models are prone to over-reliance on spurious correlations, which can often lead to poor performance on minority groups. In this paper, we identify surprising and nuanced behavior of finetuned models on worst-group accuracy via comprehensive experiments on four well-established benchmarks across vision and language tasks. We first show that the commonly used class-balancing techniques of mini-batch upsampling and loss upweighting can induce a decrease in worst-group accuracy (WGA) with training epochs, leading to performance no better than without class-balancing. While in some scenarios, removing data to create a class-balanced subset is more effective, we show this depends on group structure and propose a mixture method which can outperform both techniques. Next, we show that scaling pretrained models is generally beneficial for worst-group accuracy, but only in conjunction with appropriate class-balancing. Finally, we identify spectral imbalance in finetuning features as a potential source of group disparities - minority group covariance matrices incur a larger spectral norm than majority groups once conditioned on the classes. Our results show more nuanced interactions of modern finetuned models with group robustness than was previously known. Our code is available at https://***/tmlabonte/revisiting-finetuning. © 2024 Neural information processing systems foundation. All rights reserved.

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Learning the Eye of the Beholder: Statistical Modeling and Estimation for Personalized Color Perception 60

Learning the Eye of the Beholder: Statistical Modeling and E...

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60th Annual Allerton Conference on Communication, Control, and Computing, Allerton 2024

作者： Chen, Xuanzhou Xu, Austin Wang, Jingyan Pananjady, Ashwin School of Electrical and Computer Engineering Georgia Institute of Technology United States Salesforce AI Research Georgia Institute of Technology United States School of Industrial and Systems Engineering Georgia Institute of Technology United States

ISBN: (纸本)9798331541033

Color perception has long remained an in-triguing topic spanning vision and cognitive science, signal processing, and computer graphics. People are often classified as either 'color-normal' or 'color-blind', and it is widely accepted there are a few types of colorblindness that are the most prevalent. At the same time, empirical evidence, such as in optometry and vision science, has repeatedly suggested that categories for colorblindness only serve as approximations to real manifestations of it. With the motivation of better understanding individual-level color perception, we propose a model for color vision that unifies existing theories for color-normal and color-blind populations. This model posits a certain type of low-dimensional structure in color space according to which any given person distinguishes colors. We design an algorithm to learn this low-dimensional structure from user queries, and prove statistical guarantees on its per-formance. To collect user data, we adapt a user interface design, termed 'perceptual adjustment queries' (PAQs), to assess color perception. This user interface efficiently infers a user's color distinguishability profile from a few cognitively lightweight responses. A user study shows that our method captures individual-level differences in both color-normal and color-blind populations. © 2024 IEEE.

关键词： Color vision

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Discriminative feature encoding for intrinsic image decomposition

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Computational Visual Media 2023年第3期9卷 597-618页

作者： Zongji Wang Yunfei Liu Feng Lu Key Laboratory of Network Information System Technology(NIST) Aerospace Information Research InstituteChinese Academy of SciencesBeijing 100190China State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and EngineeringBeihang UniversityBeijing 100191China Peng Cheng Laboratory Shenzhen 518000China

Intrinsic image decomposition is an important and long-standing computer vision *** an input image,recovering the physical scene properties is *** physically motivated priors have been used to restrict the solution space of the optimization problem for intrinsic image *** work takes advantage of deep learning,and shows that it can solve this challenging computer vision problem with high *** focus lies in the feature encoding phase to extract discriminative features for different intrinsic layers from an input *** achieve this goal,we explore the distinctive characteristics of different intrinsic components in the high-dimensional feature embedding *** define feature distribution divergence to efficiently separate the feature vectors of different intrinsic *** feature distributions are also constrained to fit the real ones through a feature distribution *** addition,a data refinement approach is provided to remove data inconsistency from the Sintel dataset,making it more suitable for intrinsic image *** method is also extended to intrinsic video decomposition based on pixel-wise correspondences between adjacent *** results indicate that our proposed network structure can outperform the existing state-of-the-art.

关键词： intrinsic image decomposition deep learning feature distribution data refinement

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SvaVoting: A Novel Secret Sharing-Based Verifiable and Anonymous E-Voting Scheme in Blockchain systems 29

SvaVoting: A Novel Secret Sharing-Based Verifiable and Anony...

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29th IEEE International Conference on Parallel and Distributed systems, ICPADS 2023

作者： Zhang, Jingyu Wu, Chenghao Yang, Jin Luo, Lailong Changsha University of Science and Technology School of Computer and Communication Engineering Changsha China National University of Defense Technology Science and Technology on Information Systems Engineering Laboratory School of Systems Engineering Changsha China

ISBN: (纸本)9798350330717

E-Voting systems play a vital role in various communities, aiming to enhance the efficiency, transparency, and citizen engagement in elections. However, as technology advances, ensuring the security and reliability of e-voting systems becomes profound. While researchers have explored the integration of blockchain technology to improve e-voting systems, there still are technical challenges, particularly regarding voters' privacy, ballots' confidentiality, and system performance. To address these challenges, we propose SvaVoting, an innovative blockchain-based e-voting scheme. SvaVoting utilizes the Borda counting method and the identity-based ring signature based on symmetric primitives to anonymously verify the validity of the voter's identity and ballot format. In addition, we introduce secret sharing and a Cloud Service Provider (CSP) to conduct the final counting while preserving the privacy of the ballots. All users in the system can verify the results of CSP calculations, thereby meeting security goals such as correctness, unforgeability, anonymity and verifiability. The identity-based ring signature in our scheme provides 128-bit security, and even it can work in a quantum computing environment. Experimental results demonstrate that our solution significantly enhances the security and performance of e-voting systems, offering a practical path forward for future e-voting systems. © 2023 IEEE.

关键词： cloud service provider e-voting identity-based ring signatures post-quantum cryptography secret sharing

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Integrated electro-optic isolator on thin-film lithium niobate (Jun, 10.1038/s41566-023-01227-8, 2023)

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NATURE PHOTONICS 2023年第8期17卷 732-732页

作者： Yu, Mengjie Cheng, Rebecca Reimer, Christian He, Lingyan Luke, Kevin Puma, Eric Shao, Linbo Shams-Ansari, Amirhassan Ren, Xinyi Grant, Hannah R. R. Johansson, Leif Zhang, Mian Loncar, Marko John A. Paulson School of Engineering and Applied Sciences Harvard University Cambridge MA USA Ming Hsieh Department of Electrical and Computer Engineering University of Southern California Los Angeles CA USA HyperLight Cambridge MA USA Draper Scholar The Charles Stark Draper Laboratory Cambridge MA USA Bradley Department of Electrical and Computer Engineering Virginia Tech Blacksburg VA USA Freedom Photonics Goleta CA USA

Optical isolators are indispensable components of almost any optical system and are used to protect a laser from unwanted reflections for phase-stable coherent operation. The emergence of chip-scale optical systems, powered by semiconductor lasers that are integrated on the same chip, has generated a demand for a fully integrated optical isolator. Conventional approaches, which rely on the use of magneto-optic materials to break Lorentz reciprocity, present substantial challenges in terms of material integration. Although alternative magnetic-free approaches have been explored, an integrated isolator with a low insertion loss, high isolation ratio, broad bandwidth and low power consumption on a monolithic material platform is yet to be achieved. Here we realize a non-reciprocal travelling-wave-based electro-optic isolator on thin-film lithium niobate. The isolator enables a maximum optical isolation of 48.0 dB with an on-chip insertion loss of 0.5 dB and uses a single-frequency microwave drive power of 21 dBm. The isolation ratio remains larger than 37 dB across a tunable optical wavelength range from 1,510 to 1,630 nm. We realize a hybrid distributed feedback laser–lithium niobate isolator module that successfully protects the single-mode operation and linewidth of the laser from reflection. Our result represents an important step towards a practical high-performance optical isolator on chip.

关键词： Integrated optics Nanophotonics and plasmonics Nonlinear optics

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Augmented Reality (AR) Supporting Citizen Engagement in Circular Economy

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Circular Economy and Sustainability 2022年第3期2卷 1077-1104页

作者： Katika, Tina Karaseitanidis, Ioannis Tsiakou, Dimitra Makropoulos, Christos Amditis, Angelos Institute of Communication and Computer Systems of the School of Electrical and Computer Engineering Athens Greece Department of Water Resources and Environmental Engineering School of Civil Engineering National Technical University of Athens Athens Greece

Improving the public’s awareness of and engagement with sustainable practices is essential for transitioning from a linear to a circular economy (CE). This task is not trivial;however, research into new ways of effectively supporting awareness and engagement, especially in view of digitalization trends, is still missing. In this study, we investigate the ability of augmented reality (AR) technology to improve awareness of CE practices and to engage citizens, inclusively, in the CE approach. Specifically, we report on the development of a novel AR engagement tool and present the results of two studies undertaken using this tool to assess the reliability and validity of this engagement practice. The first study focuses on the citizens of a municipality in Greece, and the second focuses on the general public outside the municipality boundaries. Attributes related to user engagement, such as novelty, aesthetics, perceived usability, endurability, focused attention, self-efficacy, perceived learning, and interest in the topic, were assessed, as were factors affecting these attributes related to the participants’ knowledge of CE principles and exposure to similar technologies. The two studies indicate that the AR engagement tool increased social inclusion and community cohesion and was able to successfully bring CE principles and benefits to the public’s attention. Higher engagement levels were observed in participants who had limited exposure to the concept of CE prior to using the AR tool, and its use was found to improve their confidence and interest in CE. This study aspires to contribute to the ongoing discourse on the use of mobile AR and to support further evidence-based development of digital tools for public awareness and engagement. © 2022, The Author(s).

关键词： Augmented reality Circular economy Citizen engagement User engagement Web survey

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