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排序方式： 共有1627条查询结果，搜索用时 15 毫秒
991.
In terms of model predictive control (MPC) performance degradation caused by operational faults, in this article, a robust MPC strategy with active fault tolerance properties is proposed. The proposed strategy incorporates a fault supervision layer into the structure of conventional cost-contracting formulation-based robust MPC for the online update of the nominal controller model in the event of faults. The robust MPC is based on multiplant uncertainty, while the supervisory layer consists of a bank of unknown input observers and a decision-making algorithm. Simulation results in a nonlinear polymerization reactor subject to process faults demonstrate that the proposed approach offers superior performance compared to the conventional strategy. 相似文献
992.
Alexandre H.C. Anthis;Samuel Kilchenmann;Manon Murdeu;Paige J. LeValley;Morris Wolf;Charlotte Meyer;Oscar Cipolato;Mark W. Tibbitt;Jachym Rosendorf;Vaclav Liska;Thomas Rduch;Inge K. Herrmann; 《Advanced materials (Deerfield Beach, Fla.)》2024,36(23):2310301
Female sterilization via fallopian tube ligation is a common procedure; However, after the operation, over 10% of women seek re-fertilization, which is frequently unsuccessful. In addition, there is evidence that fallopian tubes contribute to the spread of endometriotic tissue as they serve as channels for proinflammatory media entering the abdominal cavity via retrograde menstruation. Here, stimuli-degradable hydrogel implants are presented for the functional, biocompatible, and reversible occlusion of fallopian tubes. The hydrogel implants, designed with customized swelling properties, mechanically occlude fallopian tubes in a high-performance manner with burst pressures reaching 255–558 mmHg, exceeding normal abdominal pressures (95 mmHg). Their damage-free removal can be achieved within 30 min using near-visible UV light or a glutathione solution, employing a method akin to standard fallopian tube perfusion diagnostics. Ultrasound-guided implant placement is demonstrated using a clinical hysteroscope in a human-scale uterus model and biocompatibility in a porcine in vivo model. Importantly, the prevention of live sperm as well as endometrial cell passage through blocked fallopian tubes is demonstrated. Overall, a multifunctional system is presented that constitutes a possible means of on-demand, reversible contraception along with the first-ever mechanical approach to abdominal endometriosis prevention and treatment. 相似文献
993.
Serena Omo-Lamai;Marco E. Zamora;Manthan N. Patel;Jichuan Wu;Jia Nong;Zhicheng Wang;Alina Peshkova;Aparajeeta Majumder;Jilian R. Melamed;Liam S. Chase;Eno-Obong Essien;Drew Weissman;Vladimir R. Muzykantov;Oscar A. Marcos-Contreras;Jacob W. Myerson;Jacob S. Brenner; 《Advanced materials (Deerfield Beach, Fla.)》2024,36(26):2312026
Lipid nanoparticles (LNPs) have become the dominant drug delivery technology in industry, holding the promise to deliver RNA to up or down-regulate any protein of interest. LNPs have mostly been targeted to specific cell types or organs by physicochemical targeting in which LNP’s lipid compositions are adjusted to find mixtures with the desired tropism. Here lung-tropic LNPs are examined, whose organ tropism derives from containing either a cationic or ionizable lipid conferring a positive zeta potential. Surprisingly, these LNPs are found to induce massive thrombosis. Such thrombosis is shown in the lungs and other organs, and it is shown that it is greatly exacerbated by pre-existing inflammation. This clotting is induced by a variety of formulations with cationic lipids, including LNPs and non-LNP nanoparticles, and even by lung-tropic ionizable lipids that do not have a permanent cationic charge. The mechanism depends on the LNPs binding to and then changing the conformation of fibrinogen, which then activates platelets and thrombin. Based on these mechanisms, multiple solutions are engineered that enable positively charged LNPs to target the lungs while ameliorating thrombosis. The findings illustrate how physicochemical targeting approaches must be investigated early for risks and re-engineered with a careful understanding of biological mechanisms. 相似文献
994.
Laura Vieira Maia de Sousa Electo Eduardo Silva Lora Fábio Cordeiro de Lisboa Fernando Bruno Dovichi Filho Oscar Almazan del Olmo 《Biofuels, Bioproducts and Biorefining》2024,18(3):675-685
There is an urgent need for energy sources with lower environmental impacts to dispose of waste generated by human activities. In this context, a holistic analysis of energy use of waste from agricultural and forestry activities, animal excreta, urban solid waste and sewage, waste from the pulp and paper industry and charcoal in Brazil is presented. Based on a bibliographic review, the current Brazilian panorama is presented in figures giving, a vision of national potential for harnessing bioenergy from this theoretical and technical potential. The QGIS3.24.2 Tisler geoprocessing tool was used to generate potentiality maps from census data of microregions and municipalities available in the IBGE database (2022) and in the Geocentric Reference System for the Americas (SIRGAS 2000). The results of map analysis by micro-regions of the primary energy from agricultural residues highlight sugar cane, corn and soybeans crops, followed by wastewater and animal excreta. They stood out amont the studied sources of biomass with technical potentials of 53.17, 15.23 and 6.81 GW, respectively. With these results, it is concluded that Brazil could enable around 75 GW installed power, reusing all biomass, potentially 12.5 PJ, without considering the 16 GW already installed from sugarcane and paper black liquor plants. 相似文献
995.
Consuelo Iveeth Morales-Santiago Oscar García-Barradas María Remedios Mendoza-López Maribel Jiménez-Fernández 《Starch - St?rke》2023,75(11-12):2300024
Chemical modification of starch from the chayote root (Sechium edule Jacq) is carried out with lauric acid and acetic anhydride. The modified starch is characterized by Fourier-transform infrared spectrometry (FTIR), X-ray diffraction (XRD), and Differential Scanning Calorimetry (DSC) and used to formulate edible films. The developed edible films are characterized based on their physicochemical and mechanical properties. The physicochemical and functional properties of starch are affected by the incorporation of the acyl and acetyl group. Both starches exhibit a significant decrease in solubility. Starch modified by the incorporation of the acyl group (lauroyl) has higher thermal stability than starch modified by the incorporation of the acetyl group. The first shows an increase in emulsifying and foaming capacity, as well as water- and oil-retention capacity, while the second exhibits adequate edible film-forming properties. The edible films develop with modified starch with acetyl group has a homogeneous surface and exhibit a higher percentage of elongation at break when they are stored at a water activity of 0.561. In accordance with the above, it is concluded that the chayote root starch modified has physicochemical and functional properties that indicate their potential utility in the food industry. 相似文献
996.
Oscar Punch Megan Danczyk Mathew Hawken Daniel J. Holland 《American Institute of Chemical Engineers》2023,69(3):e17989
Oblique collisions of two spherical particles coated with a thin layer of viscous liquid are considered. Experimental measurements are performed using particle tracking velocimetry and the results are compared to viscous force and capillary force models via numerical simulation using the discrete-element method. Comprehensive experimental data for collisions with an impact angle between 0° and 60° are presented to ensure future models can be rigorously validated. Collisions are characterized by the normal Stokes' number (a dimensionless ratio of normal inertial forces to normal viscous forces), and the normal coefficient of restitution (a dimensionless ratio of postcollisional normal velocity to precollisional normal velocity). Good agreement was found between the models and the experiments at high Stokes' number, where the models are dominated by the normal components. As the tangential forces become more significant (i.e., at low to medium Stokes' number, and high collision angle), agreement between the simulations and experiments is poorer. Furthermore, the models predict a decreasing rotational velocity with increasing Stokes' number past some critical Stokes' number. A coefficient of friction term was implemented and found to improve agreement for the rotational velocity postcollision. 相似文献
997.
Dallin M. Hardy Oscar A. Pike Bradley J. Taylor Michael L. Dunn 《Food Science & Nutrition》2023,11(3):1272-1282
Effects of holding time before cooling, cooling method, and light or dark refrigerated storage on the stability of vitamin A, vitamin C, thiamine, riboflavin, and folate were investigated in fortified and unfortified soymilk. Vitamin C loss (6%) and mild vitamin A isomerization occurred when soymilk was held hot after fortification. Cooling bottled soymilk at ambient temperature or in an ice-water bath did not affect any vitamins. Loss of riboflavin (18%) and vitamin A isomerization occurred during 12 days of light-exposed refrigerated storage, in contrast to no vitamin degradation during dark refrigerated storage. A sensory panel of youth and children indicated no significant preferences between fortified and unfortified soymilk except for color, where the lighter-colored unfortified soymilk was preferred. Acceptable vitamin stability and sensory characteristics can be achieved in fortified soymilk produced in small-scale batch processes with appropriate management of production and storage conditions. 相似文献
998.
Matthew Rogers Ahasan Habib Gilberto Teobaldi Timothy Moorsom J. Olof Johansson Luke Hedley Paul S. Keatley Robert J. Hicken Manuel Valvidares Pierluigi Gargiani Nader Alosaimi Emiliano Poli Mannan Ali Gavin Burnell Bryan J. Hickey Oscar Cespedes 《Advanced functional materials》2023,33(13):2212173
The long-term future of information storage requires the use of sustainable nanomaterials in architectures operating at high frequencies. Interfaces can play a key role in this pursuit via emergent functionalities that break out from conventional operation methods. Here, spin-filtering effects and photocurrents are combined at metal-molecular-oxide junctions in a hybrid magneto-capacitive memory. Light exposure of metal-fullerene-metal oxide devices results in spin-polarized charge trapping and the formation of a magnetic interface. Because the magnetism is generated by a photocurrent, the writing time is determined by exciton formation and splitting, electron hopping, and spin-dependent trapping. Transient absorption spectroscopy measurements show changes in the electronic states as a function of the magnetic history of the device within picoseconds of the optical pumping. The stored information is read using time-resolved scanning magneto optic Kerr effect measurements during microwave irradiation. The emergence of a magnetic interface in the picosecond timescale opens new paths of research to design hybrid magneto-optic structures operating at high frequencies for sensing, computing, and information storage. 相似文献
999.
Supun Randeni Toby Schneider EeShan C. Bhatt Oscar A. Víquez Henrik Schmidt 《野外机器人技术杂志》2023,40(2):346-367
We developed an environmentally adaptive under-ice navigation framework that was deployed in the Arctic Beaufort Sea during the United States Navy Ice Exercise in March 2020 (ICEX20). This navigation framework contained two subsystems developed from the ground up: (1) an on-board hydrodynamic model-aided navigation (HydroMAN) engine, and (2) an environmentally and acoustically adaptive integrated communication and navigation network (ICNN) that provided acoustic navigation aiding to the former. The HydroMAN synthesized measurements from an inertial navigation system (INS), ice-tracking Doppler velocity log (DVL), ICNN and pressure sensor into its self-calibrating vehicle flight dynamic model to compute the navigation solution. The ICNN system, which consisted of four ice buoys outfitted with acoustic modems, trilaterated the vehicle position using the one-way-travel-times (OWTT) of acoustic datagrams transmitted by the autonomous underwater vehicle (AUV) and received by the ice buoy network. The ICNN digested salinity and temperature information to provide model-assisted real-time OWTT range conversion to deliver accurate acoustic navigation updates to the HydroMAN. To decouple the contributions from the HydroMAN and ICNN subsystems towards a stable navigation solution, this article evaluates them separately: (1) HydroMAN was compared against DVL bottom-track aided INS during pre-ICEX20 engineering trials where both systems provided similar accuracy; (2) ICNN was evaluated by conducting a static experiment in the Arctic where the ICNN navigation updates were compared against GPS with ICNN error within low tens of meters. The joint HydroMAN-ICNN framework was tested during ICEX20, which provided a nondiverging high-resolution navigation solution—with the majority of error below 15 m—that facilitated a successful AUV recovery through a small ice hole after an 11 km untethered run in the upper and mid-water column. 相似文献
1000.
Pablo Fernandez-Comesana Francisco D. FreijedoJesus Doval-Gandoy Oscar LopezAlejandro G. Yepes Jano Malvar 《Electric Power Systems Research》2012,84(1):20-30
Power quality is a very important topic nowadays. Sensitive industrial equipment should be protected against steady-state distortions and temporary transients in the distribution lines. Typical disturbances that affect the voltage waveform quality are harmonics, imbalances and sags. This paper presents a solution to protect sensitive loads against voltage disturbances that is based on a series power line conditioner. The goal of the proposed design is that the load does not suffer considerable input voltage variations. To achieve that, a Proportional-Resonant (PR) controller and a reference generator block based on a low-gain PLL are used, which avoids a sag detection block. Furthermore, a frequency adaptation loop is included in the PR controller, which provides a proper controller operation even with utility grid frequency deviations. Finally, a hardware in the loop (HIL) test rig is used to validate the system. 相似文献