38 research outputs found
Lighting the Path to Precision Healthcare: Advances and Applications of Wearable Photonic Sensors
No full textRecent advancements in wearable photonic sensors have marked a transformative era in healthcare, enabling non-invasive, real-time, portable, and personalized medical monitoring. These sensors leverage the unique properties of light toward high-performance sensing in form factors optimized for real-world use. Their ability to offer solutions to a broad spectrum of medical challenges - from routine health monitoring to managing chronic conditions, inspires a rapidly growing translational market. This review explores the design and development of wearable photonic sensors toward various healthcare applications. The photonic sensing strategies that power these technologies are first presented, alongside a discussion of the factors that define optimal use-cases for each approach. The means by which these mechanisms are integrated into wearable formats are then discussed, with considerations toward material selection for comfort and functionality, component fabrication, and power management. Recent developments in the space are detailed, accounting for both physical and chemical stimuli detection through various non-invasive biofluids. Finally, a comprehensive situational overview identifies critical challenges toward translation, alongside promising solutions. Associated future outlooks detail emerging trends and mechanisms that stand to enable the integration of these technologies into mainstream healthcare practice, toward advancing personalized medicine and improving patient outcomes.
Learning to route efficiently with end-to-end feedback : the value of (identifiable) networked structure
No full textThesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages [71]-73).In this thesis, we introduce efficient algorithms which achieve nearly optimal instance-dependent and worst case regrets for the problem of stochastic online shortest path routing with end-to-end feedback. The setting is a natural application of the combinatorial stochastic bandits problem, a special case of the linear stochastic bandits problem. We show how the difficulties posed by the large scale action set can be overcome by the networked structure of the action set. Our approach presents a novel connection between bandit learning and shortest path algorithms. Our main contribution is a series of adaptive exploration algorithms that achieves nearly optimal O ((d²ln(T)+d³) [delta]max=[delta]²min) instance-dependent regret and Õ(d [square root]T) worst case regret at the same time. Driven by the carefully designed Top-Two Comparison (TTC) technique, the algorithms are efficiently implementable. We also conduct extensive numerical experiments to show that our proposed algorithms not only achieve superior regret performances, but also reduce the runtime drastically.by Ruihao Zhu.S.M
Control strategies for distributed energy resources in islanded microgrids
No full textModern power grids are mainly dominated by highly centralized generations (CG) such as thermal power generation. For consideration of construction cost and fuel transportation difficulties, people tend to build centralized power plant instead of distributed installations. However, with the growing concern of environmental issues, renewable energy generations (REGs) such as wind power and photovoltaics (PV), have drawn increasing attention because they have potentials to be the main future power supply source. The key feature of REGs is that they have highly topographic preferences for the location of the power plant, for example, wind power plant can often be found in offshore areas while the large-scale solar farms are usually set up in the rural solar-rich area. The microgrid (MG) concept is proposed to encounter the impact of REGs. This research is focused on islanded operation control of the microgrid because currently microgrid applications are more likely to be found in rural areas where no grid connection is available. The difficulties in microgrids can be categorized into two main aspects: power sharing among distributed generations (DGs) and global voltage regulation. The proposed methods in this thesis are improved versions of conventional linear control systems applied to microgrids. Simulations and experiments are carried out to validate the proposed theory. It is pivotal for the simulation results to match up with theoretical expectations. In this thesis, two innovative methods are presented: a fuzzy logic compensating method for faster voltage restoration after transients, and a virtual cooperative control for power sharing among DGs. The proposed methods successfully alleviate the problems and proved working by computer simulations as well as experiments on a laboratory setup. Thus, they could be potential candidates of solutions for future adoption in practice
The interpretative structural model of influencing factors of the new-type town distribution system
No full text
Fuzzy logic improved washout filter-based method for voltage restoration in DC microgrids
No full textIntegrated Battery and Heat Pump System for Decentralized Primary Frequency Control in Low-Inertia Microgrids
No full textBattery energy storage systems are often used as flexible prosumers to support frequency stability. However, they are still relatively expensive, which hinders their large-scale usage. On the other hand, an air-source heat pump system is potentially useful for frequency control in residential microgrids. Unfortunately, the thermal inertia in air-source heat pumps makes them slow for fast frequency support. In this paper, an integrated battery and heat pump system is proposed with the aim of ensuring an uninterrupted supply of heat and providing fast and sustainable frequency support that exceeds the original capacity of the battery. The transient response of the heat pump system is enhanced with battery dynamic boosting to meet the requirements of fast frequency support. With such a configuration, the proposed integrated system performs closely to a pure battery system in terms of dynamic power behavior but can provide frequency support much longer than a battery system alone. As the dynamics of air-source heat pump systems can be affected by the ambient air and condensing water temperatures, there is a risk of instable operation of such systems. Therefore, this paper discusses how to design the control for such integrated systems with the aim of ensuring robust stability. Finally, the performance of the integrated system are verified through co-simulation between Simulink and Dymola.</p
Synthesis of Silver Nanocluster-Loaded FAU Zeolites and the Application in Light Emitting Diode
No full textSilver nanoclusters that are confined inside zeolites can give off intensive tunable emission across the visible region under UV excitation. In this research, a series of silver nanoclusters loaded with R-FAU/Ag (R = Li, Na, K) zeolites were synthesized and then applied as phosphors for LEDs. The XRD and SEM measurements showed the R-FAU/Ag (R = Li, Na, K) zeolites have high crystallinity and a size distribution of 0.7–1.25 μm. Under excitations of 310–330 nm ultraviolet radiation, Li-FAU/Ag, Na-FAU/Ag, and K-FAU/Ag exhibit monotonically declining emission intensities and red-shifted emissions with peak wavelengths of 520, 527, and 535 nm, respectively. By using silicone-based epoxy resin as the packaging material, a series of LEDs were fabricated by mixing R-FAU/Ag (R = Li, Na, K) phosphors. It is indicated that the Li-FAU/Ag-LED shows the strongest intensity of 94.9 mcd, much higher than that of the LEDs made from Na-FAU/Ag (63.7 mcd) and K-FAU/Ag (74.2 mcd) phosphors. Additionally, the chromaticity coordinate of the Li-FAU/Ag-LED is located at (0.2651, 0.4073) and has a high color temperature of 7873 K. Thermal test data showed that upon heating to 440 K, the intensities of R-FAU/Ag (R = Li, Na, K) LEDs decreased to 81%, 79%, and 75% of their initial intensities measured at 280 K, respectively. This research proposes a method for regulating the luminescent properties of silver nanoclusters in FAU zeolite by modifying the extra-framework cations and demonstrates excellent performance in LED products
Gelatin/Poly (Lactic-Co-Glycolic Acid)/Attapulgite Composite Scaffold Equipped with Teriparatide Microspheres for Osteogenesis in vitro and in vivo
No full textZhenrui Zhao,1 Xiaofei Feng,1 Yuhao Zhao,1 Zhengdong Song,1 Ruihao Zhang,1 Kui Zhang,1 Yixiang He,1 Guoliang Chen,1 Jing Zhang,2 Wenji Wang3 1Department of Orthopedics, The First Clinical Medical College of Lanzhou University, Lanzhou, People’s Republic of China; 2Department of Orthopedics, Anlu People’s Hospital, Anlu, People’s Republic of China; 3Department of Orthopedics, the First Hospital of Lanzhou University, Lanzhou, People’s Republic of ChinaCorrespondence: Wenji Wang, The First Hospital of Lanzhou University, Lanzhou, 730000, People’s Republic of China, Tel +8613893221698, Email [email protected]: Given the risks associated with autologous bone transplantation and the limitations of allogeneic bone transplantation, scaffolds in bone tissue engineering that incorporate bioactive peptides are highly recommended. Teriparatide (TPTD) plays a significant role in bone defect repair, although achieving controlled release of TPTD within a bone tissue engineering scaffold remains challenging. This work reports a new approach for treatment of teriparatide using a water-in-oil-in-water (w/o/w) microspheres be equipped on gelatin (GEL)/Poly lactic-glycolic acid (PLGA)/attapulgite (ATP) scaffold.Methods: In this study, TPTD microspheres were prepared by the water-in-oil-in-water (w/o/w) double emulsion technique and GEL/PLGA/ATP composite scaffolds with different setups were prepared by salt leaching method. Both microspheres and scaffolds underwent physicochemical characterization. Mouse bone mesenchymal stem cells (BMSCs) were co-cultured with extracts from the microspheres and scaffolds to evaluate cell proliferation and osteogenesis. Four weeks post-implantation, the effectiveness of the scaffolds containing microspheres for repairing skull defects in mice was assessed.Results: Both TPTD microspheres and the GEL/PLGA/ATP scaffold significantly enhanced the proliferation and osteogenic differentiation of BMSCs. Markers of osteoblast activity, including COL1, RUNX2, OCN, and OPN, were markedly up-regulated. Further, micro-CT, histological, and immunohistochemical analyses revealed extensive new bone formation on the scaffold.Conclusion: The GEL/PLGA/ATP composite scaffold, equipped with TPTD microspheres, demonstrates significant potential for use in bone tissue engineering, providing an effective option for bone regeneration and repair in clinical applications. Keywords: teriparatide, microsphere, gelatin, PLGA, attapulgite, bone tissue engineering, bone defect, bone regeneratio
Learning to Optimize Under Non-Stationarity
No full text© 2019 by the author(s). We introduce algorithms that achieve state-of-the-art dynamic regret bounds for non-stationary linear stochastic bandit setting. It captures natural applications such as dynamic pricing and ads allocation in a changing environment. We show how the difficulty posed by the non-stationarity can be overcome by a novel marriage between stochastic and adversarial bandits learning algorithms. Defining d, BT, and T as the problem dimension, the variation budget, and the total time horizon, respectively, our main contributions are the tuned Sliding Window UCB (SW-UCB) algorithm with optimal Oe(d2/3(BT + 1)1/3T2/3) dynamic regret, and the tuning free bandit-over-bandit (BOB) framework built on top of the SW-UCB algorithm with best Oe(d2/3(BT + 1)1/4T3/4) dynamic regret
