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1. The Impact of Feature Representation on the Accuracy of Photonic Neural Networks

Author

de Queiroz, Mauricio Gomes, Jimenez, Paul, Cardoso, Raphael, Costa, Mateus Vidaletti, Abdalla, Mohab, O'Connor, Ian, Bosio, Alberto, and Pavanello, Fabio

Subjects
Computer Science - Emerging Technologies, Computer Science - Artificial Intelligence, Computer Science - Machine Learning
Abstract

Photonic Neural Networks (PNNs) are gaining significant interest in the research community due to their potential for high parallelization, low latency, and energy efficiency. PNNs compute using light, which leads to several differences in implementation when compared to electronics, such as the need to represent input features in the photonic domain before feeding them into the network. In this encoding process, it is common to combine multiple features into a single input to reduce the number of inputs and associated devices, leading to smaller and more energy-efficient PNNs. Although this alters the network's handling of input data, its impact on PNNs remains understudied. This paper addresses this open question, investigating the effect of commonly used encoding strategies that combine features on the performance and learning capabilities of PNNs. Here, using the concept of feature importance, we develop a mathematical methodology for analyzing feature combination. Through this methodology, we demonstrate that encoding multiple features together in a single input determines their relative importance, thus limiting the network's ability to learn from the data. Given some prior knowledge of the data, however, this can also be leveraged for higher accuracy. By selecting an optimal encoding method, we achieve up to a 12.3% improvement in accuracy of PNNs trained on the Iris dataset compared to other encoding techniques, surpassing the performance of networks where features are not combined. These findings highlight the importance of carefully choosing the encoding to the accuracy and decision-making strategies of PNNs, particularly in size or power constrained applications.

Published
2024
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2. SAFFIRA: a Framework for Assessing the Reliability of Systolic-Array-Based DNN Accelerators

Author

Taheri, Mahdi, Daneshtalab, Masoud, Raik, Jaan, Jenihhin, Maksim, Pappalardo, Salvatore, Jimenez, Paul, Deveautour, Bastien, and Bosio, Alberto

Subjects
Computer Science - Artificial Intelligence, Computer Science - Hardware Architecture, Computer Science - Machine Learning
Abstract

Systolic array has emerged as a prominent architecture for Deep Neural Network (DNN) hardware accelerators, providing high-throughput and low-latency performance essential for deploying DNNs across diverse applications. However, when used in safety-critical applications, reliability assessment is mandatory to guarantee the correct behavior of DNN accelerators. While fault injection stands out as a well-established practical and robust method for reliability assessment, it is still a very time-consuming process. This paper addresses the time efficiency issue by introducing a novel hierarchical software-based hardware-aware fault injection strategy tailored for systolic array-based DNN accelerators.

Published
2024

3. Complexity Assessment of Analog and Digital Security Primitives Signals Using the Disentropy of Autocorrelation

Author

Jimenez, Paul, Cardoso, Raphael, de Queiroz, Maurìcio Gomes, Abdalla, Mohab, Marchand, Cédric, Letartre, Xavier, and Pavanello, Fabio

Subjects
Computer Science - Cryptography and Security
Abstract

The study of regularity in signals can be of great importance, typically in medicine to analyse electrocardiogram (ECG) or electromyography (EMG) signals, but also in climate studies, finance or security. In this work we focus on security primitives such as Physical Unclonable Functions (PUFs) or Pseudo-Random Number Generators (PRNGs). Such primitives must have a high level of complexity or entropy in their responses to guarantee enough security for their applications. There are several ways of assessing the complexity of their responses, especially in the binary domain. With the development of analog PUFs such as optical (photonic) PUFs, it would be useful to be able to assess their complexity in the analog domain when designing them, for example, before converting analog signals into binary. In this numerical study, we decided to explore the potential of the disentropy of autocorrelation as a measure of complexity for security primitives as PUFs, TRNGs or PRNGs with analog output or responses. We compare this metric to others used to assess regularities in analog signals such as Approximate Entropy (ApEn) and Fuzzy Entropy (FuzEn). We show that the disentropy of autocorrelation is able to differentiate between well-known PRNGs and non-optimised or bad PRNGs in the analog and binary domain with a better contrast than ApEn and FuzEn. Then, we show that the disentropy of autocorrelation is able to detect small patterns injected in PUFs responses., Comment: 11 pages, 7 figures

Published
2024

4. Security layers and related services within the Horizon Europe NEUROPULS project

Author

Pavanello, Fabio, Marchand, Cedric, Jimenez, Paul, Letartre, Xavier, Chaves, Ricardo, Marastoni, Niccolò, Lovato, Alberto, Ceccato, Mariano, Papadimitriou, George, Karakostas, Vasileios, Gizopoulos, Dimitris, Bardini, Roberta, Carmona, Tzamn Melendez, Di Carlo, Stefano, Savino, Alessandro, Lerch, Laurence, Ruhrmair, Ulrich, Gutierrez, Sergio Vinagrero, Di Natale, Giorgio, and Vatajelu, Elena Ioana

Subjects
Computer Science - Cryptography and Security, Electrical Engineering and Systems Science - Signal Processing, Physics - Optics
Abstract

In the contemporary security landscape, the incorporation of photonics has emerged as a transformative force, unlocking a spectrum of possibilities to enhance the resilience and effectiveness of security primitives. This integration represents more than a mere technological augmentation; it signifies a paradigm shift towards innovative approaches capable of delivering security primitives with key properties for low-power systems. This not only augments the robustness of security frameworks, but also paves the way for novel strategies that adapt to the evolving challenges of the digital age. This paper discusses the security layers and related services that will be developed, modeled, and evaluated within the Horizon Europe NEUROPULS project. These layers will exploit novel implementations for security primitives based on physical unclonable functions (PUFs) using integrated photonics technology. Their objective is to provide a series of services to support the secure operation of a neuromorphic photonic accelerator for edge computing applications., Comment: 6 pages, 4 figures

Published
2023
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6. Hitless memory-reconfigurable photonic reservoir computing architecture

Author

Abdalla, Mohab, Zrounba, Clément, Cardoso, Raphael, Jimenez, Paul, Ren, Guanghui, Boes, Andreas, Mitchell, Arnan, Bosio, Alberto, O'Connor, Ian, and Pavanello, Fabio

Subjects
Electrical Engineering and Systems Science - Signal Processing, Computer Science - Neural and Evolutionary Computing
Abstract

Reservoir computing is an analog bio-inspired computation model for efficiently processing time-dependent signals, the photonic implementations of which promise a combination of massive parallel information processing, low power consumption, and high speed operation. However, most implementations, especially for the case of time-delay reservoir computing (TDRC), require signal attenuation in the reservoir to achieve the desired system dynamics for a specific task, often resulting in large amounts of power being coupled outside of the system. We propose a novel TDRC architecture based on an asymmetric Mach-Zehnder interferometer (MZI) integrated in a resonant cavity which allows the memory capacity of the system to be tuned without the need for an optical attenuator block. Furthermore, this can be leveraged to find the optimal value for the specific components of the total memory capacity metric. We demonstrate this approach on the temporal bitwise XOR task and conclude that this way of memory capacity reconfiguration allows optimal performance to be achieved for memory-specific tasks., Comment: The paper has been withdrawn by the authors due to their belief that the arguments and results presented in the paper are not mature enough, and includes a slight error

Published
2022

11. Complexity Assessment of Analog Security Primitives Using the Disentropy of Autocorrelation

Author

Jimenez, Paul, Cardoso, Raphael, de Queiroz, Maurìcio Gomes, Abdalla, Mohab, Marchand, Cédric, Letartre, Xavier, Pavanello, Fabio, Jimenez, Paul, Cardoso, Raphael, de Queiroz, Maurìcio Gomes, Abdalla, Mohab, Marchand, Cédric, Letartre, Xavier, and Pavanello, Fabio

Abstract

The study of regularity in signals can be of great importance, typically in medicine to analyse electrocardiogram (ECG) or electromyography (EMG) signals, but also in climate studies, finance or security. In this work we focus on security primitives such as Physical Unclonable Functions (PUFs) or Pseudo-Random Number Generators (PRNGs). Such primitives must have a high level of complexity or entropy in their responses to guarantee enough security for their applications. There are several ways of assessing the complexity of their responses, especially in the binary domain. With the development of analog PUFs such as optical (photonic) PUFs, it would be useful to be able to assess their complexity in the analog domain when designing them, for example, before converting analog signals into binary. In this numerical study, we decided to explore the potential of the disentropy of autocorrelation as a measure of complexity for security primitives as PUFs or PRNGs with analog output or responses. We compare this metric to others used to assess regularities in analog signals such as Approximate Entropy (ApEn) and Fuzzy Entropy (FuzEn). We show that the disentropy of autocorrelation is able to differentiate between well-known PRNGs and non-optimised or bad PRNGs in the analog and binary domain with a better contrast than ApEn and FuzEn. Next, we show that the disentropy of autocorrelation is able to detect small patterns injected in PUFs responses and then we applied it to photonic PUFs simulations., Comment: 11 pages, 8 figures, This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible

Published
2024

12. The impact of feature representation on the accuracy of photonic neural networks.

Author

Gomes de Queiroz, Mauricio, Jimenez, Paul, Cardoso, Raphael, Vidaletti Costa, Mateus, Abdalla, Mohab, O'Connor, Ian, Bosio, Alberto, and Pavanello, Fabio

Subjects
PHOTONICS, SCIENTIFIC community, DATA analysis, DECISION making, ACCURACY
Abstract

Photonic neural networks (PNNs) are gaining significant interest in the research community due to their potential for high parallelization, low latency, and energy efficiency. PNNs compute using light, which leads to several differences in implementation when compared to electronics, such as the need to represent input features in the photonic domain before feeding them into the network. In this encoding process, it is common to combine multiple features into a single input to reduce the number of inputs and associated devices, leading to smaller and more energy-efficient PNNs. Although this alters the network's handling of input data, its impact on PNNs remains understudied. This paper addresses this open question, investigating the effect of commonly used encoding strategies that combine features on the performance and learning capabilities of PNNs. Here, using the concept of feature importance, we develop a mathematical methodology for analyzing feature combination. Through this methodology, we demonstrate that encoding multiple features together in a single input determines their relative importance, thus limiting the network's ability to learn from the data. However, given some prior knowledge of the data, this can also be leveraged for higher accuracy. By selecting an optimal encoding method, we achieve up to a 12.3% improvement in the accuracy of PNNs trained on the Iris dataset compared to other encoding techniques, surpassing the performance of networks where features are not combined. These findings highlight the importance of carefully choosing the encoding to the accuracy and decision-making strategies of PNNs, particularly in size or power constrained applications. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Machismo and Higher Education: Examining the Relation between 'Caballerismo' and Ethnic Identity, Support Seeking, and Sense of Connectedness among College Latinos

Author

Estrada, Fernando and Jimenez, Paul

Abstract

Latino men, part of the nation's largest and fastest-growing minority group, stand to benefit from new knowledge related to factors that positively influence college persistence. In this study, the investigators examined whether "machismo"--a multidimensional and gendered social construct--was directly and indirectly associated with three outcomes associated with postsecondary success: connectedness at school, ethnic identity, and support-seeking behavior. Hierarchical moderated regression analysis on data from 140 mainly Mexican American undergraduates partially supported the hypotheses. Implications for college counselors and program coordinators are discussed, along with limitations of the study and areas for future scholarship.

Published
2018
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21. Institutional Agents' Impact on Transfer Student Success through the Avenue of Social Capital

Author

Jimenez, Paul William

Abstract

This study demonstrates that institutional agents at the community college make a significant difference in the lives of students by supporting them during the transfer process. This study brings a critical perspective to the education field by giving a voice to institutional agents at the community college level. Utilizing the social capital theory framework and Stanton-Salazar's (2001a; 2001b; 2004; 2006; 2010) concept of institutional agents, the researcher found that institutional agents played various support roles and provided several types of resources. It was necessary for participants to play several roles because students at the community college had a unique set of needs. This study used a narrative approach. Data was collected through semi-structured interviews, self-assessments, and narrative summaries with 13 institutional agents. Findings suggest that: 1) institutional agents fulfill multiple roles; 2) establishing working relationships is key to the transfer process; and 3) life histories impact the roles that institutional agents perform. Connected to the three themes in this study, the data analysis revealed that the types of roles played by participants and the level of support they provided to students were based on four variables: "1) student's needs"; "2) the institutional agent's experience"; "3) the institutional agent's level of expertise"; and "4) the institutional agent's professional role at the community college." Through the lens of the 13 participants, data emerged that can impact the work of practitioners at community colleges and four-year institutions. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]

Published
2012

23. Evaluating psychological aspects of wood and laminate products in indoor settings with pictures

Author

Jimenez, Paul, Dunkl, Anita, Eibel, Kerstin, Denk, Elisabeth, Grote, Vincent, Kelz, Christina, and Moser, Maximilian

Subjects
Wood -- Analysis -- Properties, Business, Forest products industry
Abstract

Abstract Natural materials in indoor settings influence the human organism positively. Wood is a natural material and shows similar positive effects on the individual's well-being. Because of similar looks and [...]

Published
2015
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26. Journal of Ergonomics / Assessment of Psychosocial Risks and Mental Stress at Work: The Development of the Instrument OrgFit

Author

Jimenez, Paul, Jimenez, Paul, Dunkl, Anita, Jimenez, Paul, Jimenez, Paul, and Dunkl, Anita

Abstract

To reach the goal of healthy workplaces, psychosocial risks at the workplace (also called “mental stress”) must be assessed and managed for every workplace. Psychosocial risks have to be assessed as widely as possible to support deriving tailored interventions for organizations. The OrgFit was constructed to capture all relevant areas of stress according to international requirements (e.g., according to the ISO 10075-1 or the Framework Directive 89/391/ EEC). In this paper, the psychometric properties of the OrgFit were investigated in two studies. The first study aimed at testing the factorial structure of the OrgFit with an exploratory factor analysis. In the second study, an additional factor analysis was conducted and construct validity between the dimensions of the OrgFit and work-related strain (convergent validity) and recovery/resources (discriminant validity) was tested. In both studies, Austrian workers were invited to participate in an online study by sending out e-mails. With this procedure, representative samples of 514 workers (study I) and 1200 workers (study II) were obtained to conduct the analyses. Factor structure as well as reliability and validity coefficients show satisfactory results. The internal consistencies show values between 0.79 and 0.93, which meets the requirement for analyses on an organizational level. The validity analyses indicate that the dimensions in the OrgFit are capable of assessing stress that might lead to negative strain outcomes. The OrgFit can be used in the process of risk assessment for a comprehensive assessment of mental stress and can serve as a base for developing specific process-and structure-oriented interventions.

Published
2017
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33. Testing Practices and Attitudes Toward Tests and Testing : An International Survey

Author

Evers, Arne, McCormick, Carina M., Hawley, Leslie R., Muniz, Jose, Balboni, Giulia, Bartram, Dave, Boben, Dusica, Egeland, Jens, El-Hassan, Karma, Fernandez-Hermida, Jose R., Fine, Saul, Frans, Örjan, Gintiliene, Grazina, Hagemeister, Carmen, Halama, Peter, Iliescu, Dragos, Jaworowska, Aleksandra, Jimenez, Paul, Manthouli, Marina, Matesic, Krunoslav, Michaelsen, Lars, Mogaji, Andrew, Morley-Kirk, James, Rozsa, Sandor, Rowlands, Lorraine, Schittekatte, Mark, Sümer, H. Canan, Suwartono, Tono, Urbanek, Tomas, Wechsler, Solange, Zelenevska, Tamara, Zanev, Svetoslav, Zhang, Jianxin, Evers, Arne, McCormick, Carina M., Hawley, Leslie R., Muniz, Jose, Balboni, Giulia, Bartram, Dave, Boben, Dusica, Egeland, Jens, El-Hassan, Karma, Fernandez-Hermida, Jose R., Fine, Saul, Frans, Örjan, Gintiliene, Grazina, Hagemeister, Carmen, Halama, Peter, Iliescu, Dragos, Jaworowska, Aleksandra, Jimenez, Paul, Manthouli, Marina, Matesic, Krunoslav, Michaelsen, Lars, Mogaji, Andrew, Morley-Kirk, James, Rozsa, Sandor, Rowlands, Lorraine, Schittekatte, Mark, Sümer, H. Canan, Suwartono, Tono, Urbanek, Tomas, Wechsler, Solange, Zelenevska, Tamara, Zanev, Svetoslav, and Zhang, Jianxin

Abstract

On behalf of the International Test Commission and the European Federation of Psychologists' Associations a world-wide survey on the opinions of professional psychologists on testing practices was carried out. The main objective of this study was to collect data for a better understanding of the state of psychological testing worldwide. These data could guide the actions and measures taken by ITC, EFPA, and other stakeholders. A questionnaire was administered to 20,467 professional psychologists from 29 countries. Five scales were constructed relating to: concern over incorrect test use, regulations on tests and testing, internet and computerized testing, appreciation of tests, and knowledge and training relating to test use. Equivalence across countries was evaluated using the alignment method, four scales demonstrated acceptable levels of invariance. Multilevel analysis was used to determine how scores were related to age, gender, and specialization, as well as how scores varied between countries. Although the results show a high appreciation of tests in general, the appreciation of internet and computerized testing is much lower. These scales show low variability over countries, whereas differences between countries on the other reported scales are much greater. This implies the need for some overarching improvements as well as country-specific actions.

Published
2017
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34. Evolution of a spreadsheet

Author

Jimenez, Paul

Subjects
Application installation/distribution software, Application development software, Baler Software Corp. -- Product information, Visual Baler for Windows (Application development software) -- Evaluation -- Product information -- Product/service Evaluations, Program development software -- Product information -- Evaluation -- Product/service Evaluations
Abstract

Anyone who has ever worked Microsoft Excel, or Lotus 1-2-3, or any other spreadsheet program, knows that a simple spreadsheet used by one person can quickly evolve into an application […]

Published
1995

44. ITC/EFPA Survey on test attitudes of psychologists

Author

Evers, Arne, Muniz, Jose, Bartram, Dave, Boben, Dušica, Egeland, Jens, Fernandez-Hermida, Jose, Frans, Orjan, Gintiliene Grazina, Hagemeister, Carmen, Halama, Peter, Iliescu, Dragos, Jaworowska, Aleksandra, Jimenez, Paul, Manthouli, Marina, Matešić, Krunoslav, Michaelsen, Lars, Rosza, Sandro, Schittekatte, Mark, Canan Sumer, H., and Urbanek, Tomaš

Subjects
psihološki testovi, stavovi psihologa
Abstract

The manuscript on the attitude of psychologists with respect to tests in 17 European countries is accepted by all European Psychologists. The date of publication is unknown yet. After the original data gathering was closed, still two other European countries participated (Denmark and Hungary). The results of these 19 countries were presented in the symposium International Testing Practices (chaired by Jose Muniz). On initiative of the ITC the survey will be extended to countries all over the world.

Published
2011

46. Testing Practices in the 21st Century Developments and European Psychologists' Opinions

Author

Evers, Arne, Muniz, Jose, Bartram, Dave, Boben, Dusica, Egeland, Jens, Fernandez-Hermida, Jose R., Frans, Örjan, Gintiliene, Grazina, Hagemeister, Carmen, Halama, Peter, Iliescu, Dragos, Jaworowska, Aleksandra, Jimenez, Paul, Manthouli, Marina, Matesic, Krunoslav, Schittekatte, Mark, Sumer, H. Canan, Urbanek, Tomas, Evers, Arne, Muniz, Jose, Bartram, Dave, Boben, Dusica, Egeland, Jens, Fernandez-Hermida, Jose R., Frans, Örjan, Gintiliene, Grazina, Hagemeister, Carmen, Halama, Peter, Iliescu, Dragos, Jaworowska, Aleksandra, Jimenez, Paul, Manthouli, Marina, Matesic, Krunoslav, Schittekatte, Mark, Sumer, H. Canan, and Urbanek, Tomas

Abstract

The main goal of the European Federation of Psychologists' Associations (EFPA) Standing Committee on Tests and Testing (SCTT) is the improvement of testing practices in European countries. In order to reach this goal, the SCTT carries out various actions and projects, some of which are described in this paper. To better inform its work, it decided to survey the opinions of professional psychologists on testing practices. A questionnaire of 33 items was administered to a sample of 12,606 professional psychologists from 17 European countries. The questionnaire was based on, but not identical to, one used in 2000. The new data show that the positive attitude of the respondents toward the use of tests that was obtained in 2000 has increased in most countries, with a high percentage of the surveyed psychologists using tests regularly. Five main dimensions explained 43% of the total item variance. The dimensions involve items relating to: Concern over incorrect test use, regulations on tests and testing, Internet testing, appreciation of tests, and knowledge and training relating to tests and test use. Important differences between countries were found on these five dimensions. Differences were found according to gender for four of the five dimensions and in relation to field of specialization for all five dimensions. The most commonly used tests are the classic psychometric tests of intelligence and personality: WISC, WAIS, MMPI, RAVEN, 16PF, NEO-PI-R, BDI, SCL-90. Finally, some future perspectives are discussed.

Published
2012
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48. Risk Factors and Leadership in a Digitalized Working World and Their Effects on Employees’ Stress and Resources: Web-Based Questionnaire Study

Author

Bregenzer, Anita and Jimenez, Paulino

Subjects
Computer applications to medicine. Medical informatics, R858-859.7, Public aspects of medicine, RA1-1270
Abstract

BackgroundIn today’s world of work, the digitalization of work and communication processes is increasing, and will increase even further. This increase in digitalization at the workplace brings many new aspects of working life to light, such as working in virtual teams, mobile working, expectations of being constantly available, and the need for support in adapting and learning new digital tools. These changes to the workplace can contain risks that might harm the well-being of employees. Leaders can support the well-being of their employees in terms of protecting and replenishing their work-related resources to cope with critical work demands. This so-called health-promoting leadership could serve as a buffer between risk at the workplace and critical outcomes, such as stress, by amplifying work-related resources. ObjectiveThis study’s aims were twofold. First, we wanted to investigate if risk factors related to higher digitalization at the workplace can be identified and if these risk factors have an impairing effect on the well-being of employees (eg, higher stress and lower resources). Second, we wanted to investigate if the health-impairing effects of these risk factors can be reduced by health-promoting leadership. MethodsA total of 1412 employees from Austria, Germany, and Switzerland took part in this online study and provided information on their perceived risks at the workplace, their leaders’ health-promoting behaviors, and their work-related stress and resources. ResultsThe results of a hierarchical regression analysis showed that all four risk factors of digital work (distributed team work, mobile work, constant availability, and inefficient technical support) were related to higher stress at the workplace. In addition, distributed team work and inefficient technical support were associated with lower work-related resources. A possible buffer effect of health-promoting leadership between these risks and employee well-being was visible for inefficient technical support. In particular, in the case of having fewer support opportunities in learning and using digital tools, leaders could weaken the potential critical effects on stress. As for the other risk factors, leaders might engage in a different leadership behavior to improve their employees’ well-being, as the physical distance between leaders and employees in virtual team work or mobile work could make health-promoting leadership more difficult. ConclusionsIn a digitalized working world, solutions are needed to create working conditions that benefit employees. The results of this study strongly support the importance of investigating risk factors associated with an increase in digitalization at the workplace in addition to traditional risk factors. As for leadership, leaders need to show leadership behavior adapted to a digitalized workplace in order to reduce employee stress and increase work-related resources.

Published
2021
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