Self-sustaining System Research Articles

Fail-Safe Power for Hybrid Electric Vehicles: Implementing a Self-Sustained Global Energy Management System

This article studies the energy management of a hybrid electric vehicle (HEV) equipped with a battery, an ultracapacitor system (UCS), and a fuel cell system (FCS). The energy management strategy (EMS) is designed to enable degraded operation should an energy source fail. In the considered architecture, the vehicle is not operational without a battery because it imposes the dc bus voltage; therefore, degraded operations are only considered for failures in the FCS or UCS. The objective is not to develop a new EMS for each degraded operation mode but, rather, to slightly modify the global EMS developed for normal operation. The article presents simulation and experimental validation results.

Conceptual environmental impact assessment of a novel self-sustained sanitation system incorporating a quantitative microbial risk assessment approach

In many developing countries, including South Africa, water scarcity has resulted in poor sanitation practices. The majority of the sanitation infrastructures in those regions fail to meet basic hygienic standards. This along with the lack of proper sewage/wastewater infrastructure creates significant environmental and public health concerns. A self-sustained, waterless “Nano Membrane Toilet” (NMT) design was proposed as a result of the “Reinvent the Toilet Challenge” funded by the Bill and Melinda Gates Foundation. A “cradle-to-grave” life cycle assessment (LCA) approach was adopted to study the use of NMT in comparison with conventional pour flush toilet (PFT) and urine-diverting dry toilet (UDDT). All three scenarios were applied in the context of South Africa. In addition, a Quantitative Microbial Risk Assessment (QMRA) was used to reflect the impact of the pathogen risk on human health. LCA study showed that UDDT had the best environmental performance, followed by NMT and PFT systems for all impact categories investigated including human health, resource and ecosystem. This was mainly due to the environmental credits associated with the use of urine and compost as fertilizers. However, with the incorporation of the pathogen impact into the human health impact category, the NMT had a significant better performance than the PFT and UDDT systems, which exhibited an impact category value 4E + 04 and 4E + 03 times higher, respectively. Sensitivity analysis identified that the use of ash as fertilizer, electricity generation and the reduction of NOx emissions were the key areas that influenced significantly the environmental performance of the NMT system.

Self-powered bioelectrochemical devices

Summary Autonomous bioelectrochemical devices have been described since the beginning of the 21st century. The properties and broad potential applications of such devices encouraged the development of a plethora of examples. Self-powered biodevices have been mainly used for sensing applications with different strategies reported for the detection of various important analytes. Moreover, these devices had also inspired the design and fabrication of logic- and biocomputing-based systems with further applications in logic-activated drug release for the development of sense-act-treat systems. In addition, their use as self-sustained systems for energy supply has been recently reported. This review summarizes the development and progress of self-powered biodevices with particular attention to latest advances and novel applications.

The effect of downstream turbulent region on the spiral vortex structures of a rotating-disk flow

Direct numerical simulations are carried out to investigate the role of the turbulent region in a self-sustaining system with a spiral vortex structure in the three-dimensional boundary layer over a rotating disk by solving the full Navier–Stokes equations. Two computational domains with two different azimuthal sizes,$2\unicode[STIX]{x03C0}/68$and$2\unicode[STIX]{x03C0}/32$, are used to deal with different initially dominant wavenumbers. An artificial disturbance is introduced by short-duration strong suction and blowing on the disk surface. After the flow field reaches a steady state, a turbulent region forms downstream of$Re=640$. The turbulent region is then removed using two methods: a sponge region, and application of a slip condition at the wall. In both cases, the turbulent region disappears, leaving the spiral vortex structure upstream unaffected. The results suggest that the downstream turbulent region is not related to the velocity fluctuations that grow by the global instability. In addition, when the area where the slip condition is applied is changed from$Re>630$to$Re>610$, the velocity fluctuations decay. The results indicate that the vibration source of the velocity fluctuations which grow by the global instability is located between$Re=611$and$Re=630$.

High performance all-solid-state flexible supercapacitor for wearable storage device application

Flexible power packs combining a flexible photovoltaic part with a wearable all-solid-state supercapacitor as the self-sustaining energy system to power wearable device have attracted great interest due to the increasing demands for green energy and the tendency for multi-functionalization in electronics industry. To meet this energy requirement, we report an asymmetric all-solid-state supercapacitor, then integrate with commercial flexible solar cells to develop a self-sustaining power pack. In view of comfort for wearable electronics, cotton-textile radiation-proof clothes commonly used for pregnant woman cloth (PWC) are selected as the flexible substrate to construct wearable energy storage devices, which have the properties of flexible, green, renewable, breathable and excellent conductivity. Experimental tests demonstrate that the wearable asymmetric supercapacitors with high power density and relatively large energy density, fast charge/discharge capability, light-weight, excellent reliability and flexibility can enable the solar energy captured from the environment to afford a continuous and stable output of electric power and diminish the solar energy fluctuations. The supercapacitor is assembled with the Co–Ni layered double hydroxides (Co-Ni LDH) nanosheets as the positive electrode and the FeOOH as the negative electrode. Furthermore, the fabricated self-sustaining power pack as the energy source can continuously power the press sensor for monitoring the human physiological signals regardless of the sunlight fluctuation, demonstrating its potential usage in future wearable and portable electronic devices.

The effects of an Adaptive and Distributed Transmission Power Control on the performance of energy harvesting sensor networks

The design of routing protocols for wireless sensor networks (WSNs) has been traditionally tackled by assuming battery-powered sensors, in which minimizing the power consumption was the main objective. Advances in technology and the ability to harvest energy from the environment has enabled self-sustaining systems and thus diminish the significance of network lifetime considerations in the design of WSNs. Although WSNs operated by energy-harvesting sensors are not limited by network lifetime, they still pose new design challenges due to the unstable and uncertain amount of energy that can be harvested from the environment. In this paper, we propose a new protocol for energy-harvesting sensor networks that uses adaptive transmission power to maintain the network connectivity, and distributes the traffic load on the network. Based on local information, each node dynamically adjusts its transmission power in order to maximize the network’s end-to-end performance. The simulation results indicate that the proposed protocol keeps the network connected at most of the times by using an efficient power management, outperforming greedy forwarding and dynamic duty cycle protocols in terms of packet delivery ratio, delay, and power management.

Memory effect in a self-sustained birhythmic biological system

In this paper, birhythmicity in an enzymatic-substrate reaction described by a fractional-order extended van der Pol equation is investigated. The fractional derivatives are introduced in the system equations in order to model the memory property of the biological system. The residue harmonic balance scheme is used to study the periodic motions of the considered fractional-order van der Pol equations. It is shown that depending on system parameters and the fractional derivative order, the bistability area strongly increased. This fractional oscillator is analytically mapped, onto an ordinary bistable systems with a two stable amplitude. The obtained results clearly show an interesting collapse and revival of birhythmicity with the variation of the fractional derivative order. The amplitude and frequency of the fractional order van der Pol oscillator are derived. The analysis of amplitude equation corroborates with the results obtained by numerical simulations of the fractional-order differential equations describing the system.

Probabilistic performance assessment of complex energy process systems – The case of a self-sustained sanitation system

A probabilistic modelling approach was developed and applied to investigate the energy and environmental performance of an innovative sanitation system, the “Nano-membrane Toilet” (NMT). The system treats human excreta via an advanced energy and water recovery island with the aim of addressing current and future sanitation demands. Due to the complex design and inherent characteristics of the system’s input material, there are a number of stochastic variables which may significantly affect the system’s performance. The non-intrusive probabilistic approach adopted in this study combines a finite number of deterministic thermodynamic process simulations with an artificial neural network (ANN) approximation model and Monte Carlo simulations (MCS) to assess the effect of system uncertainties on the predicted performance of the NMT system. The joint probability distributions of the process performance indicators suggest a Stirling Engine (SE) power output in the range of 61.5–73 W with a high confidence interval (CI) of 95%. In addition, there is high probability (with 95% CI) that the NMT system can achieve positive net power output between 15.8 and 35 W. A sensitivity study reveals the system power performance is mostly affected by SE heater temperature. Investigation into the environmental performance of the NMT design, including water recovery and CO2/NOx emissions, suggests significant environmental benefits compared to conventional systems. Results of the probabilistic analysis can better inform future improvements on the system design and operational strategy and this probabilistic assessment framework can also be applied to similar complex engineering systems.

Establishment of a Chaotic Synchronous Response in the Presence of a Phase Filter in a Communication Channel

The problem of establishment of a chaotic synchronous response between two chaotic self-sustained oscillator systems under the conditions of phase filtration of the chaotic signal transferred via a channel from the master to slave system is considered. The characteristics of the phase filter are equivalent to those of a filter present in a communication channel with multipath propagation.

Power and Plunder in Putin's russia

In Vladimir Putin's Russia, opaque financial flows and an equally murky network of ex-KGB officers, with its roots in the 1990s, come together in a distinctive system of corruption. This system serves dual purposes: Those at the top follow the imperative of self-enrichment, but they also find in corruption a highly effective tool for consolidating domestic political control and projecting power abroad. At home, omnipresent corruption makes property claims and business ventures contingent on the whims of the authorities, while keeping officials themselves permanently under the threat of selective punishment. Abroad, corruption serves as a key lever of Russian influence in other post-Soviet states, as well as a tool for undermining established democracies. Yet it also creates vulnerabilities that can make Russia prone to reckless and extreme measures. Although Russia's kleptocracy is a self-sustaining system, it faces a growing backlash in the forms of international sanctions and domestic discontent.

Feeding Children, Communities, and Souls

Feeding Children, Communities, and Souls

Установление хаотического синхронного отклика при наличии фазового фильтра в канале связи

AbstractThe problem of establishment of a chaotic synchronous response between two chaotic self-sustained oscillator systems under the conditions of phase filtration of the chaotic signal transferred via a channel from the master to slave system is considered. The characteristics of the phase filter are equivalent to those of a filter present in a communication channel with multipath propagation.

Self-sustainable early warning system in river currents

Half of the natural disasters are due to floods of all kinds, leaving thousands dead and injured, as well as costly material damages. An early warning system (EWS) is a vital tool to reduce disaster risk but requires components that allow rapid communication and effective response of people at risk. Contribution of advanced technology has been fundamental in the prevention of catastrophes, but unfortunately, its high cost, among other factors, does not allow its coverage to reach developing countries or to communities in areas of higher vulnerability. This was evident in Colombia, where EWS exists for large-scale phenomena, but where river floods in poor municipalities meant the country's greatest tragedies in recent years. Hence the importance of designing the self-sustaining early warning system in river currents, since it combines state-of-the-art but low-cost technological elements, allowing it to operate autonomously from alternative energy sources, continuously and accurately measure the current fluvial level, and send real-time alert signals via high-speed and efficient wireless communication protocols. Construction of a prototype of the system made it possible to test and verify the functionality and efficiency of the monitoring stations, both in accuracy and speed in measures of increasing water levels, as well as in the rapid communication of alerts to an end-user, through cell phone text messaging.

Hakluyt’s Peripatetic Discourse

In this article, I examine intellectual correspondences between two manuscripts that Richard Hakluyt (1552–1616) presented to Queen Elizabeth i in tandem in 1584: his well-known “Discourse of Western Planting” and his underappreciated “Analysis” of Aristotle’s Politics. I argue that Aristotle’s vision of the ideal political state as a materially and morally self-sustaining system, as represented in the “Analysis,” serves as the philosophical foundation of Hakluyt’s recommendations in the “Discourse” that England pursue an aggressive policy of expansionist, colonial growth. Hakluyt describes colonialism as a panacea for England’s socioeconomic issues and as the means by which England might become self-sustaining in the manner of Aristotle’s ideal state.

Conceptualizing the origin of life in terms of evolution.

In this opinion piece, we discuss how to place evolution in the context of origin-of-life research. Our discussion starts with a popular definition: 'life is a self-sustained chemical system capable of undergoing Darwinian evolution'. According to this definition, the origin of life is the same as the origin of evolution: evolution is the 'end' of the origin of life. This perspective, however, has a limitation, in that the ability of evolution in and of itself is insufficient to explain the origin of life as we know it, as indicated by Spiegelman's and Lincoln and Joyce's experiments. This limitation provokes a crucial question: What conditions are required for replicating systems to evolve into life? From this perspective, the origin of life includes the emergence of life through evolution: evolution is a 'means' of the origin of life. After reviewing Eigen's pioneering work on this question, we mention our ongoing work suggesting that a key condition might be conflicting multi-level evolution. Taken together, there are thus two questions regarding the origin of life: how evolution gets started, and how evolution produces life. Evolution is, therefore, at the centre of the origin of life, where the two lines of enquiry must meet.This article is part of the themed issue 'Reconceptualizing the origins of life'.

Neutronics physics analysis of a large fluoride-salt-cooled solid-fuel fast reactor with Th-based fuel

Fast reactors based on thorium fuel have enhanced inherent safety. Fluoride salt performs well as a coolant in high-temperature nuclear systems. In this paper, we present a reference core for a large fluoride-salt-cooled solid-fuel fast reactor (LSFR) using thorium–uranium fuel cycle. Neutronics physics of the LSFR reference core is investigated with 2D and 3D in-core fuel management strategy. The design parameters analyzed include the fuel volume fraction, power density level and continuous removal of fission products with 3D fuel shuffling that obtains better equilibrium core performance than 2D shuffling. A self-sustained core is achieved for all cases, and the core of 60% fuel volume fraction at 50 MW/m3 power density is of the best breeding performance (average breeding ratio 1.134). The LSFR core based on thorium fuel is advantageous in its high discharge burn-up of 20–30% fissions per initial heavy metal atom, small reactivity swing over the whole lifetime (to simplify the reactivity control system), the negative reactivity temperature coefficient (intrinsically safe for all cases) and accepted cladding peak radiation damage. The LSFR reactor is a good alternative option for the deployment of a self-sustained thorium-based nuclear system.

Origins of building blocks of life: A review

How and where did life on Earth originate? To date, various environments have been proposed as plausible sites for the origin of life. However, discussions have focused on a limited stage of chemical evolution, or emergence of a specific chemical function of proto-biological systems. It remains unclear what geochemical situations could drive all the stages of chemical evolution, ranging from condensation of simple inorganic compounds to the emergence of self-sustaining systems that were evolvable into modern biological ones. In this review, we summarize reported experimental and theoretical findings for prebiotic chemistry relevant to this topic, including availability of biologically essential elements (N and P) on the Hadean Earth, abiotic synthesis of life's building blocks (amino acids, peptides, ribose, nucleobases, fatty acids, nucleotides, and oligonucleotides), their polymerizations to bio-macromolecules (peptides and oligonucleotides), and emergence of biological functions of replication and compartmentalization. It is indicated from the overviews that completion of the chemical evolution requires at least eight reaction conditions of (1) reductive gas phase, (2) alkaline pH, (3) freezing temperature, (4) fresh water, (5) dry/dry-wet cycle, (6) coupling with high energy reactions, (7) heating-cooling cycle in water, and (8) extraterrestrial input of life's building blocks and reactive nutrients. The necessity of these mutually exclusive conditions clearly indicates that life's origin did not occur at a single setting; rather, it required highly diverse and dynamic environments that were connected with each other to allow intra-transportation of reaction products and reactants through fluid circulation. Future experimental research that mimics the conditions of the proposed model are expected to provide further constraints on the processes and mechanisms for the origin of life.

How Simple Could Life Be?

Will we be ever able to produce living matter artificially? Despite our increasingly precise understanding of the details of life, its fundamental principles still lie in the dark. Armed with today's technology and knowledge about living systems, it is high time for us to re-address this persistent challenge in understanding nature. Graphics: Monika Krause, MPIB.

A molecular rheostat maintains ATP levels to drive a synthetic biochemistry system

Synthetic biochemistry seeks to engineer complex metabolic pathways for chemical conversions outside the constraints of the cell. Establishment of effective and flexible cell-free systems requires the development of simple systems to replace the intricate regulatory mechanisms that exist in cells for maintaining high-energy cofactor balance. Here we describe a simple rheostat that regulates ATP levels by controlling the flow down either an ATP-generating or non-ATP-generating pathway according to the free-phosphate concentration. We implemented this concept for the production of isobutanol from glucose. The rheostat maintains adequate ATP concentrations even in the presence of ATPase contamination. The final system including the rheostat produced 24.1 ± 1.8 g/L of isobutanol from glucose in 91% theoretical yield with an initial productivity of 1.3 g/L/h. The molecular rheostat concept can be used in the design of continuously operating, self-sustaining synthetic biochemistry systems.

Incentivizing the Use of Bike Trailers for Dynamic Repositioning in Bike Sharing Systems

Bike Sharing System (BSS) is a green mode of transportation that is employed extensively for short distance travels in major cities of the world. Unfortunately, the users behaviour driven by their personal needs can often result in empty or full base stations, thereby resulting in loss of customer demand. To counter this loss in customer demand, BSS operators typically utilize a fleet of carrier vehicles for repositioning the bikes between stations. However, this fuel burning mode of repositioning incurs a significant amount of routing, labor cost and further increases carbon emissions. Therefore, we propose a potentially self-sustaining and environment friendly system of dynamic repositioning, that moves idle bikes during the day with the help of bike trailers. A bike trailer is an add-on to a bike that can help with carrying 3-5 bikes at once. Specifically, we make the following key contributions: (i) We provide an optimization formulation that generates “repositioning” tasks so as to minimize the expected lost demand over past demand scenarios; (ii) Within the budget constraints of the operator, we then design a mechanism to crowdsource the tasks among potential users who intend to execute repositioning tasks; (iii) Finally, we provide extensive results on a wide range of demand scenarios from a real-world data set to demonstrate that our approach is highly competitive to the existing fuel burning mode of repositioning while being green.