Fluidic flow delay by ionogel passive pumps in microfluidic paper-based analytical devices

[EN] A new concept for fluid flow manipulation in microfluidic paper-based analytical devices (m-PADs) is presented by introducing ionogel materials as passive pumps. m-PADs were fabricated using a new doubleside contact stamping process and ionogels were precisely photopolymerised at the inlet of the m-PADs.The ionogels remain mainly on the surface of the paper and get absorbed in the superficial paper-fibers allowing for the liquid to flow from the ionogel into the paper easily. As a proof of concept the fluid flowand mixing behaviour of two different ionogels mPADs were compared with the non-treated mPADs.It was demonstrated that both ionogels highly affect the fluid flow by delaying the flow due to their different physical and chemical properties and water holding capacities.

The Use of Cryogenic Air in Supplied Air Respiratory Protection

The Mine Improvement and New Emergency Response (MINER) Act of 2006 implemented new regulations in the underground coal mining industry that allow for the certification of non-compressed gas equipment for respiratory protection in underground coal mines. NASA’s Kennedy Space Center (KSC) Biomedical Research and Engineering Laboratory (BRL) is investigating the potential to expand cryogenic air supply systems into the mining and general industries. These investigations have, so far, resulted in four separate comparison and hardware development programs. The Propellant Handlers Ensemble (PHE) and Level “A” Ensemble Comparison (LAE): This study compared worker thermal stress while using the industry standard Level A hazardous material handling ensemble as opposed to using the similarly protective Propellant Handler’s Ensemble (PHE) that utilizes a cryogenic air supply pack, known as an Environmental Control Unit (ECU) as opposed to the compressed air Self Contained Breathing Apparatus (SCBA) used in the LAE. The research found that, in a 102°F environment, test subjects experienced significantly decreased body temperature increases, significantly decreased heart rate increases, and decreased sweat loss while performing a standard work routine while using the PHE, compared to the same test subjects performing the same routine while using the LAE. The Cryogenic Refuge Alternative Supply System (CryoRASS) project: The MINER Act of 2006 requires the operators of underground coal mines to provide refuge alternatives that can provide a safe atmosphere for workers for up to 96 hours in the event of a mine emergency. The CryoRASS project retrofitted an existing refuge chamber with a liquid air supply instead of the standard compressed air supply system and performed a 96 hour test. The CryoRASS system demonstrated that it provided a larger air supply in a significantly smaller footprint area, provided humidity and temperature control, and maintained acceptable oxygen and carbon dioxide levels in the chamber for the required amount of time. SCBA and Mine Rescue System (CryoBA/CryoASFS) Another requirement of the MINER Act is that additional emergency breathing equipment must be staged along evacuation routes to supplement the Self Contained/Self Rescue (SCSR) devices that are now required. The BRL has developed an SCBA known as the Cryogenic Breathing Apparatus (CryoBA), that has the ability to provide 2 hours of breathing air, a refill capability, and some cooling for the user. Cryogenic Air Storage and Filling Stations (CryoASFS) would be positioned in critical areas to extend evacuation time. The CryoASFS stations have a significantly smaller footprint and larger air storage capacity to similar compressed air systems. The CryoBA pack is currently undergoing NIOSH certification testing. Technical challenges associated with liquid breathing air systems: Research done by the BRL has also addressed three major technical challenges involved with the widespread use of liquid breathing air. The BRL developed a storage Dewar fitted with a Cryorefrigerator that has stored liquid air for four months with no appreciable oxygen enrichment due to differential evaporation. Testing of liquid breathing air was material and time intensive. A BRL contract developed a system that only required 1 liter of air and five minutes of time compared to the 10 liters of air and 75 minutes of time required by the old method. The BRL also developed a simple and cost effective method of manufacturing liquid air that joins a liquid oxygen tanker with a liquid nitrogen tanker through an orifice controlled “Y” fitting, mixing the two components, and depositing the mixed breathing air in a separate tanker.

Development and Verification of Control and Protection Strategies in Hybrid AC/DC Power Systems for Smart Grid Applications

Modern power networks incorporate communications and information technology infrastructure into the electrical power system to create a smart grid in terms of control and operation. The smart grid enables real-time communication and control between consumers and utility companies allowing suppliers to optimize energy usage based on price preference and system technical issues. The smart grid design aims to provide overall power system monitoring, create protection and control strategies to maintain system performance, stability and security. This dissertation contributed to the development of a unique and novel smart grid test-bed laboratory with integrated monitoring, protection and control systems. This test-bed was used as a platform to test the smart grid operational ideas developed here. The implementation of this system in the real-time software creates an environment for studying, implementing and verifying novel control and protection schemes developed in this dissertation. Phasor measurement techniques were developed using the available Data Acquisition (DAQ) devices in order to monitor all points in the power system in real time. This provides a practical view of system parameter changes, system abnormal conditions and its stability and security information system. These developments provide valuable measurements for technical power system operators in the energy control centers. Phasor Measurement technology is an excellent solution for improving system planning, operation and energy trading in addition to enabling advanced applications in Wide Area Monitoring, Protection and Control (WAMPAC). Moreover, a virtual protection system was developed and implemented in the smart grid laboratory with integrated functionality for wide area applications. Experiments and procedures were developed in the system in order to detect the system abnormal conditions and apply proper remedies to heal the system. A design for DC microgrid was developed to integrate it to the AC system with appropriate control capability. This system represents realistic hybrid AC/DC microgrids connectivity to the AC side to study the use of such architecture in system operation to help remedy system abnormal conditions. In addition, this dissertation explored the challenges and feasibility of the implementation of real-time system analysis features in order to monitor the system security and stability measures. These indices are measured experimentally during the operation of the developed hybrid AC/DC microgrids. Furthermore, a real-time optimal power flow system was implemented to optimally manage the power sharing between AC generators and DC side resources. A study relating to real-time energy management algorithm in hybrid microgrids was performed to evaluate the effects of using energy storage resources and their use in mitigating heavy load impacts on system stability and operational security.

Hybrid Power System Intelligent Operation and Protection Involving Distributed Architectures and Pulsed Loads

Efficient and reliable techniques for power delivery and utilization are needed to account for the increased penetration of renewable energy sources in electric power systems. Such methods are also required for current and future demands of plug-in electric vehicles and high-power electronic loads. Distributed control and optimal power network architectures will lead to viable solutions to the energy management issue with high level of reliability and security. This dissertation is aimed at developing and verifying new techniques for distributed control by deploying DC microgrids, involving distributed renewable generation and energy storage, through the operating AC power system. To achieve the findings of this dissertation, an energy system architecture was developed involving AC and DC networks, both with distributed generations and demands. The various components of the DC microgrid were designed and built including DC-DC converters, voltage source inverters (VSI) and AC-DC rectifiers featuring novel designs developed by the candidate. New control techniques were developed and implemented to maximize the operating range of the power conditioning units used for integrating renewable energy into the DC bus. The control and operation of the DC microgrids in the hybrid AC/DC system involve intelligent energy management. Real-time energy management algorithms were developed and experimentally verified. These algorithms are based on intelligent decision-making elements along with an optimization process. This was aimed at enhancing the overall performance of the power system and mitigating the effect of heavy non-linear loads with variable intensity and duration. The developed algorithms were also used for managing the charging/discharging process of plug-in electric vehicle emulators. The protection of the proposed hybrid AC/DC power system was studied. Fault analysis and protection scheme and coordination, in addition to ideas on how to retrofit currently available protection concepts and devices for AC systems in a DC network, were presented. A study was also conducted on the effect of changing the distribution architecture and distributing the storage assets on the various zones of the network on the system’s dynamic security and stability. A practical shipboard power system was studied as an example of a hybrid AC/DC power system involving pulsed loads. Generally, the proposed hybrid AC/DC power system, besides most of the ideas, controls and algorithms presented in this dissertation, were experimentally verified at the Smart Grid Testbed, Energy Systems Research Laboratory. All the developments in this dissertation were experimentally verified at the Smart Grid Testbed.

Hybrid power system intelligent operation and protection involving plug-in electric vehicles

Two key solutions to reduce the greenhouse gas emissions and increase the overall energy efficiency are to maximize the utilization of renewable energy resources (RERs) to generate energy for load consumption and to shift to low or zero emission plug-in electric vehicles (PEVs) for transportation. The present U.S. aging and overburdened power grid infrastructure is under a tremendous pressure to handle the issues involved in penetration of RERS and PEVs. The future power grid should be designed with for the effective utilization of distributed RERs and distributed generations to intelligently respond to varying customer demand including PEVs with high level of security, stability and reliability. This dissertation develops and verifies such a hybrid AC-DC power system. The system will operate in a distributed manner incorporating multiple components in both AC and DC styles and work in both grid-connected and islanding modes. ^ The verification was performed on a laboratory-based hybrid AC-DC power system testbed as hardware/software platform. In this system, RERs emulators together with their maximum power point tracking technology and power electronics converters were designed to test different energy harvesting algorithms. The Energy storage devices including lithium-ion batteries and ultra-capacitors were used to optimize the performance of the hybrid power system. A lithium-ion battery smart energy management system with thermal and state of charge self-balancing was proposed to protect the energy storage system. A grid connected DC PEVs parking garage emulator, with five lithium-ion batteries was also designed with the smart charging functions that can emulate the future vehicle-to-grid (V2G), vehicle-to-vehicle (V2V) and vehicle-to-house (V2H) services. This includes grid voltage and frequency regulations, spinning reserves, micro grid islanding detection and energy resource support. ^ The results show successful integration of the developed techniques for control and energy management of future hybrid AC-DC power systems with high penetration of RERs and PEVs.^

Synthesis of novel organic semiconductors for optoelectronic devices

This thesis describes the synthesis and characterisation of novel conjugated organic materials with optoelectronic application. The first chapter provides an introduction about organic semiconductors and in particular about their working principle from a physical and chemical point of view. An overview of the most common types of solar cells is provided, including examples of some of the best performing materials. The second chapter describes the synthesis of a new library of flavin derivatives as potential active materials for optoelectronic applications. Flavins are natural redox-active molecules, which show potential application in optoelectronics, thanks to their stability and versatility. FPF-Flavins, for instance, could be used either as acceptor units in push-pull polyconjugated systems or as acceptor unit in dyes for DSSCs. In the same chapter a first attempt of synthesising bis-flavins to be used as N-type semiconductors in BHJ devices is described. The third chapter describes the successful synthesis and characterization of a series of conjugated organic molecules based on the benzothiadiazole moiety. Among these, three molecules containing ferrocene as donor unit were tested as sensitizers for DSSCs, reporting a PCE of 0.3% as the best result. Further studies indicated a significant problem of charge recombination which limits the performance. A near-infrared absorbing push-pull polymer, based on BbT as acceptor unit, was also synthesised and tested in BHJ devices as P-type semiconductor in blend with PC71BM, showing a VOC of 0.71 V. Finally, the last chapter describes the synthesis of several tetrathiafulvalene derivatives in order to explore this moiety as donor unit in dyes for DSSCs and as HTM for perovskite-based solar cells. In particular, two very simple dyes were synthesised and implemented in DSSCs reporting a PCE 0.2% and 0.4%, respectively. The low efficiency was associated to the tendency to aggregate at the solid state, with the absorption shifting from the visible to the infrared range. A conjugated molecule, containing a DPP core, was also synthesised and tested as HTM for perovskite solar cells. The best reported PCE of 7.7% was obtained without any additives. A case study about dehalogenation and “halogen dance” in TTF iodide is also presented.