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영상-관성-거리 센서 융합 기반의 다중 무인기 위치 추정
최준호,Kevin Christiansen Marsim,정명우,류기환,김지원,명현 제어·로봇·시스템학회 2023 제어·로봇·시스템학회 논문지 Vol.29 No.11
Multi-robot state estimation is crucial for real-time and accurate operation, especially in complex environments where a global navigation satellite system cannot be used. Many researchers employ multiple sensor modalities, including cameras, LiDAR, and ultra-wideband (UWB), to achieve real-time state estimation. However, each sensor has specific requirements that might limit its usage. While LiDAR sensors demand a high payload capacity, camera sensors must have matching image features between robots, and UWB sensors require known fixed anchor locations for accurate positioning. This study introduces a robust localization system with a minimal sensor setup that eliminates the need for the previously mentioned requirements. We used an anchor-free UWB setup to establish a global coordinate system, unifying all robots. Each robot performs visual-inertial odometry to estimate its ego-motion in its local coordinate system. By optimizing the local odometry from each robot using inter-robot range measurements, the positions of the robots can be robustly estimated without relying on an extensive sensor setup or infrastructure. Our method offers a simple yet effective solution for achieving accurate and real-time multi-robot state estimation in challenging environments without relying on traditional sensor requirements.
Alexander Andersen Juhl,Peer Christiansen,Tine Engberg Damsgaard 한국유방암학회 2016 Journal of breast cancer Vol.19 No.4
Purpose: Persistent pain is a common side effect of breast cancer treatment. The present study aimed to assess the prevalence, associated treatment-related factors, and the type of pain (neuropathic or nociceptive) in patients who had undergone a unilateral mastectomy. Methods: All women who underwent a unilateral mastectomy at a University Hospital between 2009 and 2013 were eligible for inclusion. Women with breast reconstruction or active cancer were excluded. Participants were mailed a questionnaire evaluating the prevalence, location, intensity, and frequency of surgical site pain. Additionally, the painDETECT ®, a validated instrument to evaluate neuropathic pain, was mailed to all participants. Results: A total of 305 women were included, and of them, 261 (85.6%) completed the study questionnaire. After a median follow-up period of 3.0 years, 100 women (38.3%) reported experiencing pain at the surgical site. Body mass index ≥30 kg/m2, radiation therapy, and axillary lymph node dissection were significantly associated with persistent pain in univariate models. However, only body mass index ≥30 kg/m2 was independently associated with persistent pain (odds ratio, 2.13; 95% confidence interval, 1.06–4.27; p=0.034) in a multivariate analysis. Of the patients reporting pain, 71.0% were unlikely to have a neuropathic pain component. A moderate, but highly significant, positive correlation was observed between the pain intensity and the painDETECT® score (rs=0.47, p<0.001). Conclusion: Persistent pain after breast cancer treatment continues to have a high prevalence. Our results indicate that the largest proportion of patients experiencing persistent pain after breast cancer treatment do not have a clear neuropathic pain component.
Nanna Blicher Albert,Anne Jacobine Erlang Christiansen,Alexander Josiassen 글로벌지식마케팅경영학회 2023 Global Marketing Conference Vol.2023 No.07
E-commerce has seen significant growth since the outbreak of the COVID-19 pandemic. This has led to changes in consumer preferences and increased pressure on companies to develop effective e-commerce and social media capabilities to retain customers. This study examines the impact of these capabilities on customer retention and firm performance by collecting quantitative data from 160 small U.S. e-commerce companies in the fashion industry. The study finds that customer retention positively relates to firm performance and that factors, including cross-device shopping, payment methods, page speed, standard delivery time, Pinterest activity, and Instagram activity, significantly impact customer retention. The study suggests strategies for companies to remain competitive in the dynamic e-commerce landscape.
Xuan Zongzhe,Peng Qiuyue,Larsen Thomas,Gurevich Leonid,de Claville Christiansen Jesper,Zachar Vladimir,Pennisi Cristian Pablo 한국조직공학과 재생의학회 2023 조직공학과 재생의학 Vol.20 No.2
BACKGROUND: Reliable in vitro cellular models are needed to study the phenotypic modulation of smooth muscle cells (SMCs) in health and disease. The aim of this study was to optimize gelatin methacrylate (GelMA)/alginate hydrogels for bioprinting three-dimensional (3D) SMC constructs. METHODS: Four different hydrogel groups were prepared by mixing different concentrations (% w/v) of GelMA and alginate: G1 (5/1.5), G2 (5/3), G3 (7.5/1.5), and G4 (7.5/3). GelMA 10% was used as control (G5). A circular structure containing human bladder SMCs was fabricated by using an extrusion-based bioprinter. The effects of the mixing ratios on printability, viability, proliferation, and differentiation of the cells were investigated. RESULTS: Rheological analysis showed that the addition of alginate significantly stabilized the change in mechanical properties with temperature variations. The group with the highest GelMA and alginate concentrations (G4) exhibited the highest viscosity, resulting in better stability of the 3D construct after crosslinking. Compared to other hydrogel compositions, cells in G4 maintained high viability ([80%), exhibited spindle-shaped morphology, and showed a significantly higher proliferation rate within an 8-day period. More importantly, G4 provided an optimal environment for the induction of a SMC contractile phenotype, as evidenced by significant changes in the expression of marker proteins and morphological parameters. CONCLUSION: Adjusting the composition of GelMA/alginate hydrogels is an effective means of controlling the SMC phenotype. These hydrogels support bioprinting of 3D models to study phenotypic smooth muscle adaptation, with the prospect of using the constructs in the study of therapies for the treatment of urethral strictures.
Vertebro-Vertebral Fistula Occlusion Using a Woven EndoBridgeTM-Device
Dahl Rasmus Holmboe,Ghasemi-Rad Mohammad,Eskesen Vagn,Frevert Susanne Christiansen,Sølling Christine,Benndorf Goetz 대한신경중재치료의학회 2023 Neurointervention Vol.18 No.3
Vertebro-vertebral fistulas (VVFs) are vascular lesions that may develop after trauma or spontaneously in association with connective tissue disorders. We present a rare case of a post-traumatic VVF in a young patient presenting with a painless swelling and a bruit in her left upper neck. Digital subtraction angiography showed an arteriovenous fistula between the left vertebral artery (VA) and the vertebral venous plexus with significant steal phenomenon. Endovascular therapy was performed using a Woven EndoBridge<sup>TM</sup> (WEB)-device combined with coils that allowed preservation of the VA. The patient fully recovered from her symptoms and follow-up imaging showed stable occlusion. In conclusion, VVFs can be effectively treated using intrasaccular flow diverters such as the WEB-device, allowing for complete and stable occlusion while preserving the parent artery.
Evaluating C-RAN Fronthaul Functional Splits in Terms of Network Level Energy and Cost Savings
Aleksandra Checko,Andrijana P. Avramova,Michael S. Berger,Henrik L. Christiansen 한국통신학회 2016 Journal of communications and networks Vol.18 No.2
The placement of the complete baseband processing in acentralized pool results in high data rate requirement and inflexibilityof the fronthaul network, which challenges the energy andcost effectiveness of the cloud radio access network (C-RAN). Recently,redesign of the C-RAN through functional split in thebaseband processing chain has been proposed to overcome thesechallenges. This paper evaluates, by mathematical and simulationmethods, different splits with respect to network level energy andcost efficiency having in the mind the expected quality of service. The proposed mathematical model quantifies the multiplexinggains and the trade-offs between centralization and decentralizationconcerning the cost of the pool, fronthaul network capacityand resource utilization. The event-based simulation captures theinfluence of the traffic load dynamics and traffic type variation ondesigning an efficient fronthaul network. Based on the obtained results, we derive a principle for fronthauldimensioning based on the traffic profile. This principle allows forefficient radio access network with respect to multiplexing gainswhile achieving the expected users’ quality of service.