Article
Multidisciplinary Sciences
Luiz G. A. Alves, Diego Rybski, Haroldo V. Ribeiro
Summary: Urban scaling theory explains the increasing returns to scale of urban wealth indicators based on the per capita increase of human interactions within cities. Incoming commuters' contribution to urban GDP depends on whether the product of population and commuters exceeds a certain threshold for increasing returns to scale.
SCIENTIFIC REPORTS
(2021)
Article
Mechanics
Wenda Xie, Ting Shi, Bing Ge, Shusheng Zang
Summary: This paper describes the use of experimentally validated computational fluid dynamics methods to study the similarity performance of various models scaled by the Da(I) criterion. The results show that the geometric scaling factor has a significant impact on the velocity distribution, with obvious stretching of the reaction zone when Q<0.3. Increasing either the equivalence ratio (ER) or the swirl number (SW) reduces the deviation in the velocity distribution. In addition, the concept of degree of similarity is introduced to determine whether the reaction flow field of a model maintains similarity with the prototype.
Article
Engineering, Mechanical
Yuqin Cheng, Kun Liu, Zili Wang
Summary: In this study, a velocity-stress-mass (VSG) method based on the Johnson-Cook equation (VSG-JC) is proposed to determine the relationship between a full-size structure and its scaled-down model. The methodology is verified using theoretical and numerical solutions and compared with a method based on the Cowper-Symonds equation (VSG-CS). The results show that the VSG-JC method is more accurate in predicting the dynamic response of scaled models, demonstrating its validity for evaluating the scaling behavior of sandwich structures subjected to impact loads.
JOURNAL OF SANDWICH STRUCTURES & MATERIALS
(2023)
Article
Physics, Multidisciplinary
Xu-Jie Lin, Er-Jian Liu, Yitao Yang, Xiang-Yu Jia, Xiao-Yong Yan
Summary: Heavy trucks play a crucial role in urban freight systems and exhibit both superlinear and sublinear scaling relationships with urban population size. Previous models have explained these scaling relationships, but a comprehensive model that can explain a wide range of scaling exponents is still lacking. In this study, we propose a partially mixing city operation model that quantifies the mixability of the urban population, providing insights into the mechanism of allometric scaling in urban freight systems and offering a new framework for other scaling relationships in cities.
Article
Multidisciplinary Sciences
Antonio Curado, Bruno Damasio, Sara Encarnacao, Cristian Candia, Flavio L. Pinheiro
Summary: Public procurement refers to the purchase of services, goods, or works by public sector entities, and this accounts for a significant share of OECD countries' expenditures. The study found that public procurement expenditure scales sublinearly with population size, indicating an economy of scale for public spending with increasing city population. By looking at Scale-Adjusted Indicators by contract categories, a richer local characterization of municipalities based on the similarity of procurement activity can be identified, providing policymakers with a more appropriate foundation for comparative analysis.
Article
Engineering, Biomedical
Giuseppe Schiavone, Nicolas Vachicouras, Yashwanth Vyza, Stephanie P. Lacour
Summary: The research explores new electrode system technologies and stimulation protocols to improve electrode performance and confirm therapeutic efficacy. The study finds a hard, intrinsic upward scalability limit to the electrode radius depending largely on conductor technology. A simple analytical formula predicting the maximum size of a stimulation electrode as a function of stimulation parameters and conductor resistance is provided.
JOURNAL OF NEURAL ENGINEERING
(2021)
Article
Mechanics
Suyash Verma, Benjamin R. S. Freeman, Arman Hemmati
Summary: The variation in thrust generation of an oscillating foil was evaluated numerically for different conditions. The accuracy of laminar scaling in predicting thrust was found to weaken at higher reduced frequencies and amplitudes. Pressure was found to dominate the total thrust generated, especially at high frequencies. The quantitative assessment was supported by the qualitative evaluation of the vortex structure.
Article
Multidisciplinary Sciences
Elisa Heinrich Mora, Cate Heine, Jacob J. Jackson, Geoffrey B. West, Vicky Chuqiao Yang, Christopher P. Kempes
Summary: Urban scaling analysis explores common features and income inequality across cities, showing that income in the least wealthy decile scales linearly with city population while income in the most wealthy decile scales superlinearly. Larger cities have increasingly unequally distributed benefits. The shapes of income distributions also change with city size, with mean, variance, skewness, and kurtosis increasing. This study suggests that interactions within cities leading to superlinear scaling may only be seen in upper deciles, encouraging further exploration of heterogeneous models.
JOURNAL OF THE ROYAL SOCIETY INTERFACE
(2021)
Editorial Material
Biology
Yiyang Ye, Jie Lin
Summary: Why does the density of a cell remain constant as it changes size during the cell cycle?
Article
Mathematics, Applied
J. Petrillo, J. Glimm
Summary: This paper presents an extension to the Kolmogorov-Obukhov refined similarity hypotheses for universal fully-developed turbulence and applies it to a multifractal model. The development is related to the fully-developed turbulence state and describes the coupling between velocity fluctuations and averaged energy dissipation at all orders. The reparametrization of the She-Leveque model is unique and preserves its original forecasts while being infinitely divisible.
PHYSICA D-NONLINEAR PHENOMENA
(2022)
Article
Nanoscience & Nanotechnology
Haozhi Yuan, Kai Wu, Yaqiang Wang, Jinyu Zhang, Gang Liu, Jun Sun
Summary: The surface wrinkling of metal films on spherical PDMS substrates is induced by thermal contraction. A novel scaling law among wrinkle wavelength, film thickness, and substrate radius was discovered experimentally and rationalized theoretically, showing universality and robustness across different materials. The results provide new insights into the wrinkling phenomenon of spherical surfaces and demonstrate a predictive pathway to create wrinkling patterns as needed.
SCRIPTA MATERIALIA
(2021)
Article
Materials Science, Multidisciplinary
Jente Vandersmissen, Randy a. Meijer, Johneph Sukham, Aloys Erkelens, Jan bonne Aans, Ewold Verhagen
Summary: In this study, we demonstrate the optical readout and actuation of nanomechanical motion using plasmonic fields in a nanoscale gap waveguide. By coupling the change of the plasmonic gap mode with the mechanical displacement of the top layer, we are able to sense and excite nanomechanical vibrations with high sensitivity.
OPTICAL MATERIALS EXPRESS
(2023)
Article
Multidisciplinary Sciences
Ryan C. Taylor, Xiaofan Liang, Manfred D. Laubichler, Geoffrey B. West, Christopher P. Kempes, Marion Dumas
Summary: Scaling theory has been a powerful tool for understanding the tradeoffs and complementarities between core functions of institutions. Our research shows that universities and colleges scale in a surprisingly systematic fashion following simple power-law behavior. By comparing different sectors within higher education organizations, we find distinct regimes of scaling in relation to enrollment, expenditures, revenues, graduation rates, and economic added value.
Editorial Material
Multidisciplinary Sciences
Jeremie Bec, Giorgio Krstulovic, Takeshi Matsumoto, Samriddhi Sankar Ray, Dario Vincenzi
Summary: Turbulence is a challenging problem in physics and mathematics, and recent interdisciplinary research has provided new insights and approaches to solve it.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2022)
Article
Mechanics
Wenda Xie, Ting Shi, Bing Ge, Shusheng Zang
Summary: This study experimentally and numerically investigates the suitability of the Da(I) and Re criteria for scaling the geometry of a lean premixed swirl combustor. The results showed that the constant Da(I) model exhibited a similar trend to the prototype, while the constant Re model exhibited an adverse trend. The flow fields of the prototype and the scaled models were similar under different flow strengths, but the velocity distribution of the rotating jet in the scaled models was significantly lower than that of the prototype. The NOx emissions of the scaled models were significantly higher for the constant Re model, while consistent with the prototype for the constant Da(I) model.
Review
Nanoscience & Nanotechnology
Arne Laucht, Frank Hohls, Niels Ubbelohde, M. Fernando Gonzalez-Zalba, David J. Reilly, Soren Stobbe, Tim Schroeder, Pasquale Scarlino, Jonne Koski, Andrew Dzurak, Chih-Hwan Yang, Jun Yoneda, Ferdinand Kuemmeth, Hendrik Bluhm, Jarryd Pla, Charles Hill, Joe Salfi, Akira Oiwa, Juha T. Muhonen, Ewold Verhagen, M. D. LaHaye, Hyun Ho Kim, Adam W. Tsen, Dimitrie Culcer, Attila Geresdi, Jan A. Mol, Varun Mohan, Prashant K. Jain, Jonathan Baugh
Summary: Nanostructures have enabled the exploration of quantum behavior, unconventional states, and various quantum phenomena in systems such as nano-optomechanical systems, low-dimensional structures, molecular devices, and more. The intersection of nanotechnology and quantum science/technology has led to significant advancements in quantum research, with applications in quantum metrology, sensing, computing, and communication. This mutual interaction between the two fields has resulted in exciting scientific breakthroughs in the past decade, with promising prospects for the future.
Article
Optics
Chirag Murendranath Patil, Guillermo Arregui, Morten Mechlenborg, Xiaoyan Zhou, Hadiseh Alaeian, Pedro David Garcia, Soren Stobbe
Summary: We report optical transmission measurements on suspended silicon photonic-crystal waveguides with a glide symmetry and slow light. The chiral light-matter interaction is strongly enhanced by this combination, but the interplay between slow light and backscattering has not been experimentally investigated in such waveguides. Photonic-crystal resonators consisting of glide-symmetric waveguides terminated by reflectors were built, and transmission measurements and evanescent coupling were used to map out the dispersion relation. The results show excellent agreement with theory and reveal the potential of these waveguides for applications in slow-light devices and chiral quantum optics.
Article
Optics
Marcus Albrechtsen, Babak Vosoughi Lahijani, Soren Stobbe
Summary: We present a theoretical study on dielectric bowtie cavities and identify two distinct confinement regimes. Distinguishing between these regimes is crucial for future research on nanocavities and enables strongly enhanced light-matter interaction over large bandwidths.
Article
Materials Science, Multidisciplinary
Babak Vosoughi Lahijani, Nicolas Descharmes, Raphael Barbey, Gael D. Osowiecki, Valentin J. Wittwer, Olga Razskazovskaya, Thomas Sudmeyer, Hans Peter Herzig
Summary: This article investigates the propagation properties of optical modes supported at the free surface of a 1D photonic crystal. Structures optimized for long-distance propagation of optical surface waves are designed and fabricated, and the existence of optical surface waves in the visible spectral range is experimentally demonstrated for the first time.
ADVANCED OPTICAL MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
O. Florez, G. Arregui, M. Albrechtsen, R. C. Ng, J. Gomis-Bresco, S. Stobbe, C. M. Sotomayor-Torres, P. D. Garcia
Summary: Nanopatterned materials have the capability to control mechanical vibrations and enable the suppression of vibrations and propagation of hypersonic guided modes at room temperature. The structuring of solids to possess a phononic stop band can eliminate thermal vibrations. Experimental results demonstrate that the shamrock crystal geometry on a nanostructured silicon membrane can efficiently manipulate phonons, with potential applications in optomechanics and signal processing transduction.
NATURE NANOTECHNOLOGY
(2022)
Article
Multidisciplinary Sciences
Marcus Albrechtsen, Babak Vosoughi Lahijani, Rasmus Ellebaek Christiansen, Vy Thi Hoang Nguyen, Laura Nevenka Casses, Soren Engelberth Hansen, Nicolas Stenger, Ole Sigmund, Henri Jansen, Jesper Mork, Soren Stobbe
Summary: This study integrates fabrication constraints into topology optimization to achieve the strongest light-matter interaction in a photonic nanocavity. The researchers demonstrated a nanocavity with a small mode volume, high quality factor, and compact footprint, using near-field optical measurements.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
G. Arregui, R. C. Ng, M. Albrechtsen, S. Stobbe, C. M. Sotomayor-Torres, P. D. Garcia
Summary: Confining photons in cavities enhances the interaction between light and matter. We have demonstrated how sidewall roughness in air-slot photonic-crystal waveguides can induce Anderson-localized modes with high quality factors and mode volumes below the diffraction limit. The interaction between these disorder-induced optical modes and in-plane mechanical modes is governed by a distribution of coupling rates, leading to mechanical amplification via optomechanical backaction. This study opens up new possibilities for exploring complex systems with mutually coupled degrees of freedom.
PHYSICAL REVIEW LETTERS
(2023)
Article
Optics
Christian Anker Rosiek, Guillermo Arregui, Anastasiia Vladimirova, Marcus Albrechtsen, Babak Vosoughi Lahijani, Rasmus Ellebaek Christiansen, Soren Stobbe
Summary: This study investigates the practical value of topological protection in reciprocal photonics. Measurements of propagation losses in valley-Hall topological waveguides in the slow-light regime show no evidence of topological protection against backscattering on structural defects. Light's unique properties support the development of photonic quantum technologies, optical interconnects, and novel sensors, but losses due to absorption or backscattering are a key limitation.
Article
Optics
Soren Engelberth Ansen, Guillermo Arregui, Ali Nawaz Babar, Marcus Albrechtsen, Babak Vosoughi Lahijani, Rasmus Ellebaek Christiansen, Soren Stobbe
Summary: We designed and fabricated a grating coupler that can interface suspended silicon photonic membranes with free-space optics in a single-step lithography and etching process in 220 nm silicon device layers. The coupler design achieved high transmission and low reflection by combining two-dimensional shape optimization and three-dimensional parameterized extrusion. The experimentally verified coupler had a transmission of -6.6 dB (21.8%), a 3 dB bandwidth of 75 nm, and a reflection of -27 dB (0.2%).
Article
Physics, Multidisciplinary
Guilhem Madiot, Ryan C. Ng, Guillermo Arregui, Omar Florez, Marcus Albrechtsen, Soren Stobbe, Pedro D. Garcia, Clivia M. Sotomayor-Torres
Summary: This study investigates the optomechanical generation of coherent phonons at 6.8 GHz frequency, operating at room temperature. By using a suspended 2D silicon phononic crystal cavity with an air-slot, the phononic waveguide is turned into an optomechanical platform that allows for fine control of phonons using light. This development could potentially lead to the advancement of phononic circuitry and coherent manipulation of other solid-state properties.
PHYSICAL REVIEW LETTERS
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
O. Florez, G. Arregui, J. Gomis-Bresco, M. Albrechtsen, S. Stobbe, C. M. Sotomayor Torres, P. D. Garcia
Summary: A complete mechanical band gap in the GHz region of a 2D phononic crystal over the entire Brillouin zone was measured using the noninvasive Brillouin light scattering technique.
2021 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO)
(2021)
