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Design and control of a novel variable stiffness series elastic actuator
No full textThis article expounds the design and control of a new variable stiffness series elastic actuator (VSSEA). It is established by employing a modular mechanical design approach that allows us to effectively optimize the stiffness modulation characteristics and power density of the actuator. The proposed VSSEA possesses the following features: no limitation in the work range of output link; a wide range of stiffness modulation (∼20 N·m/rad to ∼1 KN·m/rad); low-energy-cost stiffness modulation at equilibrium and nonequilibrium positions; compact design and high torque density (∼36 N·m/kg); and high-speed stiffness modulation (∼3000 N·m/rad/s). Such features can help boost the safety and performance of many advanced robotic systems, e.g., a cobot that physically interacts with unstructured environments and an exoskeleton that provides physical assistance to human users. These features can also enable us to utilize variable stiffness property to attain various regulation and trajectory tracking control tasks only by employing conventional controllers, eliminating the need for synthesizing complex motion control systems in compliant actuation. To this end, it is experimentally demonstrated that the proposed VSSEA is capable of precisely tracking the desired position and force control references through the use of the conventional proportional-integral-derivative controllers
Developmental scaffolding with large language models
No full textExploration and self-observation are key mechanisms of infant sensorimotor development. These processes are further guided by parental scaffolding to accelerate skill and knowledge acquisition. In developmental robotics, this approach has been adopted often by having a human acting as the source of scaffolding. In this study, we investigate whether Large Language Models (LLMs) can act as a scaffolding agent for a robotic system that aims to learn to predict the effects of its actions. To this end, an object manipulation setup is considered where one object can be picked and placed on top of or in the vicinity of another object. The adopted LLM is asked to guide the action selection process through algorithmically generated state descriptions and action selection alternatives in natural language. The simulation experiments that include cubes in this setup show that LLM-guided (GPT3.5-guided) learning yields significantly faster discovery of novel structures compared to random exploration. However, we observed that GPT3.5 fails to effectively guide the robot in generating structures with different affordances such as cubes and spheres. Overall, we conclude that even without fine-tuning, LLMs may serve as a moderate scaffolding agent for improving robot learning, however, they still lack affordance understanding which limits the applicability of the current LLMs in robotic scaffolding tasks.TÜBİTAK ; Osaka University ; New Energy and Industrial Technology Development Organization ; Japan Society for the Promotion of Scienc
Conflict-based negotiation strategy for human-agent negotiation
No full textDay by day, human-agent negotiation becomes more and more vital to reach a socially beneficial agreement when stakeholders need to make a joint decision together. Developing agents who understand not only human preferences but also attitudes is a significant prerequisite for this kind of interaction. Studies on opponent modeling are predominantly based on automated negotiation and may yield good predictions after exchanging hundreds of offers. However, this is not the case in human-agent negotiation in which the total number of rounds does not usually exceed tens. For this reason, an opponent model technique is needed to extract the maximum information gained with limited interaction. This study presents a conflict-based opponent modeling technique and compares its prediction performance with the well-known approaches in human-agent and automated negotiation experimental settings. According to the results of human-agent studies, the proposed model outpr erforms them despite the diversity of participants’ negotiation behaviors. Besides, the conflict-based opponent model estimates the entire bid space much more successfully than its competitors in automated negotiation sessions when a small portion of the outcome space was explored. This study may contribute to developing agents that can perceive their human counterparts’ preferences and behaviors more accurately, acting cooperatively and reaching an admissible settlement for joint interests.CHIST-ERA ; TÜBİTAKPublisher versio
Measurements of inclusive and differential cross sections for the Higgs boson production and decay to four-leptons in proton-proton collisions at √s=13 TeV
No full textMeasurements of the inclusive and differential fiducial cross sections for the Higgs boson production in the H -> ZZ -> 4 l ( l = e, mu) decay channel are presented. The results are obtained from the analysis of proton-proton collision data recorded by the CMS experiment at the CERN LHC at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 138 fb(-1). The measured inclusive fiducial cross section is 2.73 +/- 0.26 fb, in agreement with the standard model expectation of 2.86 +/- 0.1 fb. Differential cross sections are measured as a function of several kinematic observables sensitive to the Higgs boson production and decay to four leptons. A set of double-differential measurements is also performed, yielding a comprehensive characterization of the four leptons final state. Constraints on the Higgs boson trilinear coupling and on the bottom and charm quark coupling modifiers are derived from its transverse momentum distribution. All results are consistent with theoretical predictions from the standard model.BMBWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, FAPERGS, and FAPESP (Brazil); MES and BNSF (Bulgaria); CERN; CAS, MoST, and NSFC (China); MINCIENCIAS (Colombia); MSES and CSF (Croatia); RIF (Cyprus); SENESCYT (Ecuador); MoER, ERC PUT and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRI (Greece); NK-FIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); MES (Latvia); LAS (Lithuania); MOE and UM (Malaysia); BUAP, CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MOS (Montenegro); MBIE (New Zealand); PAEC (Pakistan); MES and NSC (Poland); FCT (Portugal); MESTD (Serbia); MCIN/AEI and PCTI (Spain); MOSTR (Sri Lanka); Swiss Funding Agencies (Switzerland); MST (Taipei); MHESI and NSTDA (Thailand); TUBITAK and TENMAK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (U.S.A.).
Individuals have received support from the Marie-Curie programme and the European Research Council and Horizon 2020 Grant, contract Nos. 675440, 724704, 752730, 758316, 765710, 824093, 884104, and COST Action CA16108 (European Union); the Leventis Foundation; the Alfred P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the F.R.S.-FNRS and FWO (Belgium) under the "Excellence of Science - EOS" - be.h project n. 30820817; the Beijing Municipal Science & Technology Commission, No. Z191100007219010 and Fundamental Research Funds for the Central Universities (China); the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Hellenic Foundation for Research and Innovation (HFRI), Project Number 2288 (Greece); the Deutsche Forschungsgemeinschaft (DFG), under Germany's Excellence Strategy - EXC 2121 "Quantum Universe" - 390833306, and under project number 400140256 - GRK2497; the Hungarian Academy of Sciences, the New National Excellence Program - uNKP, the NKFIH research grants K 124845, K 124850, K 128713, K 128786, K 129058, K 131991, K 133046, K 138136, K 143460, K 143477, 2020-2.2.1-ED-2021-00181, and TKP2021-NKTA-64 (Hungary); the Council of Science and Industrial Research, India; the Latvian Council of Science; the Ministry of Education and Science, project no. 2022/WK/14, and the National Science Center, contracts Opus 2021/41/B/ST2/01369 and 2021/43/B/ST2/01552 (Poland); the FundacAo para a Ciencia e a Tecnologia, grant CEECIND/01334/2018 (Portugal); the National Priorities Research Program by Qatar National Research Fund; MCIN/AEI/10.13039/501100011033, ERDF "a way of making Europe", and the Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de Excelencia Maria de Maeztu, grant MDM-2017-0765 and Programa Severo Ochoa del Principado de Asturias (Spain); the Chulalongkorn Academic into Its 2nd Century Project Advancement Project, and the National Science, Research and Innovation Fund via the Program Management Unit for Human Resources & Institutional Development, Research and Innovation, grant B05F650021 (Thailand); the Kavli Foundation; the Nvidia Corporation; the SuperMicro Corporation; the Welch Foundation, contract C-1845; and the Weston Havens Foundation (U.S.A.).Publisher versio
I ponti di turchi di Enzo Siviero: Haliç Metro Crossing Bridge
No full textIn the Cultural Evaluation and Architectural Characterization of the Bridge of of the Halic metro, in Istanbul, designed by Hakan Kiran, the group coordinated by Siviero, has been able to reconcile the technical demands of structural design with the
necessary construction of relationships of meaning and form with the urban context in which the building is inscribed
Discrete dipole approximation with surface interaction
No full textIn this chapter, we discuss a methodology to determine absorption and scattering cross sections of particles of different size and shape placed on substrates. This approach is based on the principles of discrete dipole approximation (DDA); however, the interaction matrix between the dipoles is modified to include the effect of the semiinfinite surface by including dipole reflections represented by Sommerfeld integrals. Depending on the direction of an incident plane wave, the particle will be illuminated by the combination of the incident wave with the reflected, transmitted, or evanescent wave. In order to explore problems involving nanomanufacturing or sensing, a new DDA-SI algorithm is constructed as an open-source computational toolbox in a MATLAB environment. Later, two other algorithms (DDA-SI-v and zDDA-SI) were developed to increase the speed of calculations. All three algorithms were considered for atomic force microscopy-based manufacturing applications using dielectric and metallic nanoparticles. Examples of different cases are provided at the end of the chapter
Zaragoza’nın tipolojik sürecinin sıra evler üzerinden incelenmesi
No full textBu çalışma, Zaragoza'dakiyapılı çevrenin geçirdiği tipolojik süreci, farklı yapı tiplerinin ortaya çıkışına neden olan koşulları göz önüne alarak tanımlamayı amaçlamaktadır. Zaragoza şehrinin, MÖ 14'te Roma İmparatorluğu tarafından Saldube adlı bir Kelt-İber şehrinin bulunduğu konumda bir askeri koloni olarak kurulduğu düşünülmektedir. Mevcut teorik rekonstrüksiyonlar arkeolojik buluntulardan yararlanarak Caesar Augusta'nın birinci yüzyıldaki kentsel dokusunu Roma tipi avlulu evlerden oluşan ızgara plan üzerine yerleştirmektedir. Çalışma kapsamında Zaragoza Coğrafya ve Kadastro Enstitüsü için 1911'de hazırlanan yapı rölövelerinden yararlanarak kentin tipolojik planı hazırlanmış ve bu plan doğrultusunda ilgili bölge arkeolojik verilerin de incelenmesiyle tarihsel sürecin ortaya çıkardığı bir organizma (Strappa, Carlotti, Camiz, 2017)olarak analiz edilmiştir. Kent dokusunun geçirdiği değişimlerin ana hatlarını belirlemek için ilk adım olarak kentin surlarla çevrili bölgesinde bulunan sıra evlerin tipolojik süreci çözümlenmiş ve mevcut diğer yapı tipleriyle olan ilişkisi ortaya koyulmuştur.
https://tnum.org.tr/index.php/tnum/article/view/27
Colorization of passive radiative cooling coatings using plasmonic effects
No full textPassive radiative cooling is a novel concept and is likely to be important for building and industrial energy ef-ficiency efforts, as it will significantly contribute to the reduction of thermal management costs for electronic equipment. In most studies, radiative cooling devices are not considered for their colors; although to find a large number of users, it must be attractive to designers or architects, who usually pay significant attention to aesthetic and decorative aspects of paints. Since the majority of the coatings reported in the literature are white, there is also a need to develop color-coordinated paints and coatings. Here, we propose an approach for designing a simple structure of colored radiative cooling devices assisted by a plasmonic structures. We show that they can be tuned as desired to produce different hues of colored coatings, while maintaining adequate radiative cooling power. To demonstrate the conflicting functions of color display and radiative cooling performance, we use a bowtie nanoantenna as a color-displaying structure to investigate how the structural factors affect the cooling performance and color display accordingly. We show that periodic high index-low index alternating layers (SiO2-TiO2) on top of a thin silver layer cause broadband reflection in visible and near-infrared spectrums, while to achieve narrowband absorption in the visible region, which leads to the desired colorization, the bowtie nanoantenna is utilized. We report that by changing the structural parameters of a nanoantenna, the resonance peaks are controlled to yield a narrowband absorption in the visible spectrum to create different colors. More-over, our results indicate that although adding coloration structure to a conventional radiative cooling system reduces the cooling power by around 30%, it is still reasonable high, around 60 W/m2, and is still suitable to be used for daytime radiative cooling where control over the color is needed. Acceptable cooling power while ability to control the coloration make the proposed colored radiative cooling a potential candidate to be used in various applications, both in high end buildings or for thermal management of electronic equipment.Air Force Office of Scientific Researc
Green infrastructure in water management: Stakeholder perceptions from South East Queensland, Australia
No full textGreen infrastructure (GI) originated in landscape architecture and landscape ecology and is widely used as an approach to sustainable water management. However, there is no commonly accepted definition of GI for water management in the literature. This research was undertaken in South East Queensland (SEQ), Australia, which has experienced a long-term cycle of floods and droughts. The research employed the Q-sort methodology supplemented with semi-structured interviews to understand perceptions of GI amongst various stakeholders. Twenty-seven research participants included design, planning, and engineering practitioners, government officers, scientists and community members familiar with GI. Our findings indicate these participants regard GI as a broad concept containing both natural and engineered semi-natural assets offering multiple benefits and functions, yet rarely recognised its economic benefits. Participants were divided on GI's effectiveness for drought management. We propose a new, consolidated definition of GI for stormwater management: “GI is a strategically planned network of high-quality natural and semi-natural assets that mimics natural processes, with multiple benefits and multifunctionality, such as enhancing stormwater management and providing environmental quality, with social and economic benefits”. We recommend that water management-related policies, strategies, plans, and design guidelines in SEQ and elsewhere, should include a consistent definition of GI for water management to assist professional and community understanding and inform decision-making about flood and drought.Queensland University of Technolog
Single item periodic review inventory control with sales dependent stochastic return flows
No full textRetailers have to deal with increasing levels of product returns as the shares of e-commerce sales soars. With this increase, it is no longer feasible to dispatch returned products to outlets or landfills, hence retailers must re-evaluate them both to maximize profit and to minimize their environmental impact. Our objective is to study a retailer's optimal inventory control policy under product returns to maximize expected profit which is the sales revenue minus the procurement, backorder, holding, and salvage costs incurred in a finite horizon. We model a period's returns to be stochastically dependent on the previous period's sales quantity. Using dynamic programming formulation, we solve for the optimal periodic review inventory policy and provide structural results on the optimal policy of the final period. Through numerical studies, we show that incorporating detailed sales-dependent returns could increase a retailer's expected profit by 23%. Ignoring this dependency in determining the optimal inventory policy results with increased order frequency, higher levels of backorders and more leftovers which could eventually end up in a landfill, but above all could lead to a significant overestimation of the resulting profit.TÜBİTA