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Although microsensors nowadays can save money, energy, and lives, highly functional devices can exhaust a tiny battery very quickly. Harvesting ambient energy can help replenish the battery, but only when an ambient source is available. Unfortunately, many embedded microsensors are small, stationary, and enclosed, so thermal gradients, motion, and light are absent. Wireless power in these cases is...
When supplied well and with little power losses, multifunctional microsystems can add life- and cost-saving intelligence to hospitals, factories, and cars. Unfortunately, fitting the multiple power supplies that diverse subsystems require into millimeters is challenging. One reason for this is, although efficient and therefore necessary, inductors are bulky. And supplying several outputs with one...
A fundamental challenge wireless microsystems face is size, and in consequence, lifetime because tiny batteries exhaust quickly. Although small fuel cells and atomic sources store more energy than lithium-ion batteries and super capacitors, they source less power, so they cannot power as many functions. Small batteries and capacitors, however, cannot sustain life for long. Thankfully, the environment...
Wireless microsensors can sense and share data that can save lives, energy, and money. Recharging or replacing thousands of tiny, easily exhaustible batteries, however, is too costly. Fortunately, photovoltaic (PV) cells can generate 100x more power from sunlight than other transducers can from motion, heat, or radiation. But since PV cells cannot supply the milliwatts that microsystems can at times...
The purpose of this paper is to present a scheduling solution based on information theory principles to schedule real-time tasks. We propose the mathematical background for using information as a parameter in real-time systems as well as the relationship between information and utilization. We present a new dynamic priority scheduling solution that selects the task with the highest amount of information...
The main challenge with microsensors is limited space, because tiny batteries store little energy. Harvesting energy helps, but only when ambient energy is available. And even then, power is low because miniaturized transducers harness little power. This is why managing how and when to schedule functional tasks is so important. This paper proposes a schedule that requires the battery to hold only...
Satellites are artificial objects that orbit around the earth with the purpose of either collecting or transmitting information. To provide power to these satellites, solar panels are used to convert solar energy into usable electrical energy. The electricity generated by these solar panels is then stored in rechargeable batteries that provide power during instances when sunlight is not readily available...
Although microsystems today require less power than ever before, they still cannot fit large enough batteries to sustain them for months or years at a time. Ambient energy is appealing, but only when available, which is often not the case for embedded sensors. Transmitting power wirelessly is more practical in these applications. Tiny receivers, however, capture a small fraction of the power that...
Wireless microsensors in factories, hospitals, cars, and so on process information that can save money, energy, and lives. Unfortunately, tiny batteries exhaust quickly, and replacing so many of them frequently is impractical. This is why recharging them with ambient energy is so appealing, especially when vibrations, for example, are abundant and steady. Still, tiny piezoelectric transducers draw...
This chapter focuses on how to most efficiently transfer and condition harvested energy and power with emphasis on the imposed requirements of microscale dimensions. The driving objective is to maximize operational life by reducing all relevant power losses. The chapter therefore briefly reviewes the electrical characteristics and needs of available harvesting sources and the operational implications...
The purpose of this paper is to present the mathematical background for using entropy in real-time scheduling as well as the relationship between entropy and utilization. We present a new scheduling algorithm based on entropy to schedule tasks in real-time systems. The goal is to minimize the uncertainty of the scheduling problem by executing the task with the highest entropy first without missing...
The purpose of this paper is to present an interdisciplinary research project in order to attract engineering students to the area of aerospace systems. The Puerto Rico NASA Space Grant (PRSGC) is a joint program between the University of Puerto Rico-Mayagüez (UPRM), the Inter American University of Puerto Rico-Bayamon (UIPRB) and other educational institutions. The desired impact of the project is...
This paper presents the second Electric Power Supply (EPS) prototype designed for supplying power to the Space Plasma Ionic Charge Analyzer (SPICA) CubeSat. In order to power the CubeSat with higher efficiency, Gallium Arsenide (GaAs) solar panels are mounted on each side of the cube, converting solar power into electrical energy. Solar cell area limitations require maximizing the available electrical...
Wireless microsensors and other miniaturized electronics cannot only monitor and better-manage power consumption in emerging small- and large-scale applications (for space, military, medical, agricultural, and consumer markets) but also add energy-saving and performance-enhancing intelligence to old, expensive, and difficult-to-replace infrastructures and tiny contraptions in difficult-to-reach places...
Piezoelectric harvesters are popular today because they typically draw more power from kinetic energy in motion than electrostatic and electromagnetic systems. Still, tiny transducers only derive a small fraction of what is available. Thankfully, raising the damping force with which transducers draw power increases that fraction, except overinvesting battery energy for that purpose can overdamp the...
One of the essential issues about operation of electric vehicles in transportation is to attend the demand of charging electric batteries with high reliability. This paper presents different connection schemes to feed the chargers from the distribution system, in three particular cases: private vehicle in residential garage, vehicles in shopping centers, and for bus parking chargers. For the two first...
Although energy in vibrations is often vast, the electrostatic force with which tiny variable capacitors draw power from motion is miniscule, so output power is low. Thankfully, extracting energy at higher voltages generates more power because the electrical damping force that impedes motion to draw power is stronger. Clamping the transducer to a battery is convenient in this respect, but limiting...
Wireless microsystems can add performance-enhancing, energy-saving, and networked intelligence to inaccessible places like the human body and large infrastructures like factories, hospitals, and farms. For this, they require an onboard source and a power-conditioning circuit that supply microwatts about a prescribed dc voltage. And since tiny dc batteries store little energy, switched-inductor dc-dc...
A major challenge with emerging microsensors, biomedical implants, and other portable devices is operational life, because tiny batteries exhaust quickly. And even though 1g fuel cells store 5 to 10× more energy than 1g Li-ion batteries, fuel cells supply 10 to 20× less power [1]. This means fuel cells last longer with light loads and Li-ion batteries output more power across shorter periods. Therefore,...
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