Constant Energy Supply Research Articles

Minimum Secrecy Throughput Maximization in Wireless Powered Secure Communications

This paper investigates a wireless powered secure communication network (WPSCN), in which the legitimate users have no constant energy supply and need to be wireless powered for information transmitting. The harvest-then-transmit protocol is adopted in the WPSCN, i.e., the energy access point (EAP) first transfers energy to legitimate users through energy beamforming, and then, the legitimate users transmit their data to the information access point (IAP) by time-division multiple access. Since an eavesdropper intercepts users’ uplink information, the EAP creates artificial noise to cripple the interception capability of the eavesdropper. For providing a secrecy throughput balancing across different legitimate users, we aim to maximize the minimum secrecy throughput of all users via time allocation, energy beamforming, and artificial noise design. To this end, a low-complexity two-stage algorithm is proposed. In the first stage, without taking into account the eavesdropper's wiretapping, we design time allocation and energy beamforming by solving the problem of minimum throughput maximization, which is convex and can be easily solved. In the second stage, two easily implementable strategies are proposed for artificial noise design so as to strengthen the noise power at the eavesdropper and simultaneously reduce the noise power at the IAP. Simulation results show that the performance of the proposed approach is close to the upper bound and not sensitive to scenario settings, which confirms the effectiveness of the proposed method.

PPARδ, a Potential Therapeutic Target for Heart Disease.

The nuclear receptor peroxisome proliferator-activated receptor δ (PPARδ) can transcriptionally regulate target genes. PPARδ exerts essential regulatory functions in the heart, which requires constant energy supply. PPARδ plays a key role in energy metabolism, controlling not only fatty acid (FA) and glucose oxidation, but also redox homeostasis, mitochondrial biogenesis, inflammation, and cardiomyocyte proliferation. PPARδ signaling is impaired in the heart under various pathological conditions, such as pathological cardiac hypertrophy, myocardial ischemia/reperfusion, doxorubicin cardiotoxicity and diabetic cardiomyopathy. PPARδ deficiency in the heart leads to cardiac dysfunction, myocardial lipid accumulation, cardiac hypertrophy/remodeling and heart failure. This article provides an up-today overview of this research area and discusses the role of PPARδ in the heart in light of the complex mechanisms of its transcriptional regulation and its potential as a translatable therapeutic target for the treatment of cardiac disorders.

Transforming Urban Dichotomies and Challenges of South Asian Megacities: Rethinking Sustainable Growth of Dhaka, Bangladesh

Dhaka, the capital of Bangladesh, is the eleventh largest megacity city in the world, with a population of 18.2 million people living in an area of 1528 km2. This city profile traces the trajectories of its urban development to becoming a megacity and characterizes its emerging challenges due to informal urbanization and climate change impacts. Due to rapid population growth and uncontrolled urbanization, Dhaka currently faces various socio-economic and environmental challenges in aspects such as providing basic urban services; reliable transportation framework; constant water and energy supply; effective sanitation; sustainable waste management and affordable housing. Moreover, the urban setting has further deteriorated as Dhaka is already facing various adverse impacts of climate change. Studies predict that most of the urban sectors, public health and surrounding agriculture and fisheries in Dhaka will be severely impacted by climate change. Dhaka is trying to transform its existing “incremental development” model to an “integrated development” framework in order to effectively mitigate its extreme urban challenges. The future of Dhaka city significantly relies on the successful execution of integrated infrastructure and service planning, development, and management practices, operating under an accountable and good governance system.

Application of Operando Methods for Characterisation of Structural Evolution in Electrochemical Systems

Energy storage has in recent times become a critical area of research due to the widespread adoption of portable electronic devices, and the need to derive more energy from sources other than fossil fuels. Alternative, renewable energy sources such as wind or solar are only able to produce power intermittently and thus the development of large-scale energy storage systems and the associated infrastructure to deliver a constant supply of energy will be key to a successful transition away from fossil fuels.[1, 2] Lithium-ion batteries (LIBs) appear ubiquitously in a variety of electronic devices where it is favoured for its high energy density and dependable cycling characteristics. Although recent work has also shown the viability of other battery systems, e.g. Na-ion, K-ion, Li-air, the number of publications regarding lithium-ion battery systems continues to outnumber any other battery chemistry,[3] which highlights that the LIB system is still an area with room for further innovation despite it being a well-established technology. In commercial LIBs, graphite has remained the negative electrode material of choice since first generation LIBs, where graphite was coupled with a LiCoO2 positive electrode. Second generation systems involving LiFePO4 (LFP) positive electrodes were later developed, and more recently third generation systems which utilise Li(NixMnyCoz)O2 or Li(NixCoyAlz)O2 positive electrodes are beginning to be deployed in commercially produced LIBs.[4, 5] These systems have been optimised by their commercial vendors for electrochemical performance and production, however there is significant room for further investigation in regards to how these materials evolve and perform in devices, especially under different conditions or extreme conditions. Ex situ data and recent in situwork undertaken by our group has provided some insight,[6-9] however many open questions about battery performance and its relation to electrode materials remain unanswered. For example: phase evolution as a function of current rate, temperature, and transition metal composition (i.e., Ni:Co:Mn ratio), overcharging/undercharging and the structural consequences, or the influence of nano-sizing to phase evolution and its relationship to applied current. It is therefore important to characterise these systems thoroughly in order to find methods by which to improve their performance, e.g. optimal transition metal ratios and voltage cut-offs, and provide a foundation for the next-generation of LIBs which will be required to meet the growing demand for portable electronic devices. To answer the questions proposed above, we use in operando neutron diffraction to study fully-functioning, unmodified devices. Neutron diffraction is ideal for performing operando experiments as the neutron beam can easily penetrate the battery casing and components, and the high intensity allows for short collection times which provides data with excellent time resolution. By correlating the electrochemical data with the diffraction data we are able to establish relationships between the electrochemical state of the device and the structural evolution taking place. Here we present findings from recent studies of commercial LIBs with different cathode materials. We have investigated devices using LiFePO4 , where we were able to establish a novel relationship between the structural kinetics of the electrode materials and the cycling history of the battery,[10] as well as devices using Li(NixMnyCoz)O2with various Ni:Mn:Co ratios in order to compare their performance and structural stability at high voltage.[7] [1] H. Pan, Y.-S. Hu, L. Chen, Energy & Environmental Science, 6 (2013) 2338.[2] D. Lindley, Nature, 463 (2010) 18. [3] J.C. Pramudita, D. Sehrawat, D. Goonetilleke, N. Sharma, Advanced Energy Materials, (2017) 1-20.[4] M.S. Whittingham, Chemical Reviews, 104 (2004) 4271-4302.[5] J.W. Fergus, Journal of Power Sources, 195 (2010) 939-954.[6] J. Li, R. Petibon, S. Glazier, N. Sharma, W.K. Pang, V.K. Peterson, J.R. Dahn, Electrochimica Acta, 180 (2015) 234-240.[7] R. Petibon, J. Li, N. Sharma, W.K. Pang, V.K. Peterson, J.R. Dahn, Electrochimica Acta, 174 (2015) 417-423.[8] N. Sharma, W.K. Pang, Z. Guo, V.K. Peterson, ChemSusChem, 8 (2015) 2826-2853.[9] N. Sharma, V.K. Peterson, Journal of Solid State Electrochemistry, 16 (2012) 1849-1856.[10] D. Goonetilleke, J.C. Pramudita, M. Hagan, O.K. Al Bahri, W.K. Pang, V.K. Peterson, J. Groot, H. Berg, N. Sharma, Journal of Power Sources, 343 (2017) 446-457. Figure 1

Biology of glucose metabolization in cancer cells

Abstract Cancer is a disease at the cellular level involving heritable disorders in cellular control mechanism. Cancer cells also need to adapt their metabolism to survive and multiply under the metabolically compromised conditions provided by the tumor microenvironment. Tumor cells alter their metabolism to maintain unregulated cellular proliferation and survival, but this transformation leaves them reliant on constant supply of nutrients and energy. They alter their metabolism to support their rapid proliferation and expansion across the body. After the discovery of based on the altered cancer cell metabolism in 1930, loads of studies have shed light on several aspects of cancer metabolism with a common goal to find new ways for effectively eliminating tumor cells by targeting their energy metabolism. Research has directed most of its resources to elucidate the causes, prevention and possible cure for cancer, yet the process has been elusive claiming human lives more than ever. This disease is a manifestation of etiological and pathological disturbances of mechanisms that control cell division, differentiation and metabolism. 50% of all human tumors carry genetic alterations that lead to the inactivation of some tumor suppressor proteins. Cancer cells are shown to experience characteristic changes in their metabolic programs, including increased uptake of glucose, enhanced rates of glutaminolysis and fatty acids synthesis, suggesting that metabolic shifts supports tumor cells growth and survival. In this review, we summarized the major concepts of glucose metabolization and explore the molecular basis of aerobic glycolysis of cancer cells.

Energy Storage as Part of a Secure Energy Supply

AbstractThe current energy system is subject to a fundamental transformation: A system that is oriented towards a constant energy supply by means of fossil fuels is now expected to integrate increasing amounts of renewable energy to achieve overall a more sustainable energy supply. The challenges arising from this paradigm shift are currently most obvious in the area of electric power supply. However, it affects all areas of the energy system, albeit with different results. Within the energy system, various independent grids fulfill the function of transporting and spatially distributing energy or energy carriers, and the demand‐oriented supply ensures that energy demands are met at all times. However, renewable energy sources generally supply their energy independently from any specific energy demand. Their contribution to the overall energy system is expected to increase significantly. Energy storage technologies are one option for temporal matching of energy supply and demand. Energy storage systems have the ability to take up a certain amount of energy, store it in a storage medium for a suitable period of time, and release it in a controlled manner after a certain time delay. Energy storage systems can also be constructed as process chains by combining unit operations, each of which cover different aspects of these functions. Large‐scale mechanical storage of electric power is currently almost exclusively achieved by pumped‐storage hydroelectric power stations. These systems may be supplemented in the future by compressed‐air energy storage and possibly air separation plants. In the area of electrochemical storage, various technologies are currently in various stages of research, development, and demonstration of their suitability for large‐scale electrical energy storage. Thermal energy storage technologies are based on the storage of sensible heat, exploitation of phase transitions, adsorption/desorption processes, and chemical reactions. The latter offer the possibility of permanent and loss‐free storage of heat. The storage of energy in chemical bonds involves compounds that can act as energy carriers or as chemical feedstocks. Thus, they are in direct economic competition with established (fossil fuel) supply routes. The key technology here – now and for the foreseeable future – is the electrolysis of water to produce hydrogen and oxygen. Hydrogen can be transformed by various processes into other energy carriers, which can be exploited in different sectors of the energy system and/or as raw materials for energy‐intensive industrial processes. Some functions of energy storage systems can be taken over by industrial processes. Within the overall energy system, chemical energy storage technologies open up opportunities to link and interweave the various energy streams and sectors. Chemical energy storage not only offers means for greater integration of renewable energy outside the electric power sector, it also creates new opportunities for increased flexibility, novel synergies, and additional optimization. Several examples of specific energy utilization are discussed and evaluated with respect to energy storage applications.The article describes various technologies for energy storage and their potential applications in the context of Germany's Energiewende, i.e. the transition towards a more sustainable energy system. Therefore, the existing legal framework defines some of the discussions and findings within the article, specifically the compensation for renewable electricity providers defined by the German Renewable Energy Sources Act, which is under constant reformation. While the article is written from a German perspective, the authors hope this article will be of general interest for anyone working in the areas of energy systems or energy technology.

Social and Economic Implications for the Smart Grids of the Future

IntroductionWe live in a world that is set up on consuming energy day after day and hour after hour. The whole existence of humanity is dependent on energy. One simply cannot imagine an everyday live without a comfort of having electricity at our homes, functioning street lamps lighting up our streets, an unlimited supply of gasoline to fill up the tanks of our cars, or the smooth flow of natural gas in our pipes to heat up our homes in winter.The best representation of energy that is always there, always on demand, is, without any doubt, electricity. Growing up in any developed Western country in the 1980s, the 1990s, or even later would leave one firmly believing that electricity was ubiquitous and always on demand whenever one needed it. Surely, blackouts happened from time to time, but they were relatively seldom. The energy supply worked on the money and there was always hot water in the pipes, the heating kept the homes warm in winter, and the lights, TV and radio were always working.It is hard to imagine surviving several days without electricity. All of us, consumers or business, depend on its constant and undisrupted flow (Janda et al., 2013; Abrham et al., 2015). In a way, we believe in electricity like if it was some form of a new religion (Strielkowski and Cabelkova, 2015).Sure enough, one can imagine a day or two of hiking and sleeping in a tent by the campfire. But what if this unintentionally turns into a longer stay perhaps lasting for a week or even longer? All of a sudden one will start to realize that her or his smartphone is discharged and stopped working all together, the flashlight ran out of batteries, it is not possible to call or e-mail anyone, friends' status on Facebook cannot be checked and all thin lines with the outside world are broken. For most of the people life in such situation would become too hard to bear. Surely, some people might find it adventurous and romantic to go into the wild and sit by the campfires but many of these endeavours end up badly unless you drag the power generators, solar panels and other things with you. Even the participants of the Burning Man (called Burners), famous art festival that takes place in Nevada's at the end of every August and includes creating an entire self-sustainable and self-supporting city (called Black Rock City) in the lifeless desert bring with them enormous amounts of equipment, supplies and fuel to light up the desert in one-week long magic carnival and to create all sorts of comfort for themselves - including smartphone charging stations, live music podia, discotheques, saunas, movie theatres, and much more (Kozinets, 2002). Everyone depends on constant supply of energy, even the modern-day couch journalists who try to shape up the public opinion from the comfort of their homes without even going into the field (Cabelkova et al., 2015).Overall, humankind grows too comfortable taken the electricity supply of energy as granted. But of all this can change one day and the scenarios might vary. For instance, the NBC Revolution TV series (2012-2014) shows the world in 2027, about 15 years after a hypothetical secret government weapon project that used nanotechnology as a means of draining electricity from all power devices went awry. The opening line for each of the series' episode starts with the following lines:We lived in an electric world. We relied on it for everything. And then the power went out. Everything stopped working. We weren't prepared. Fear and confusion led to panic. The lucky ones made it out of the cities. The government collapsed. Militias took over, controlling the food supply and stockpiling weapons. We still don't know why the power went out. But we 're hopeful someone will come and light the way (Revolution, 2012).These words very precisely portray the current situation and the people's attitude to today's power systems: we rely upon them too much and we cannot do without them. …

Nutritional and Bioenergetic Considerations in Critically Ill Patients with Acute Neurological Injury.

The brain, due to intensive cellular processes and maintenance of electrochemical gradients, is heavily dependent on a constant supply of energy. Brain injury, and critical illness in general, induces a state of increased metabolism and catabolism, which has been proven to lead to poor outcomes. Of all the biochemical interventions undertaken in the ICU, providing nutritional support is perhaps one of the most undervalued, but potentially among the safest, and most effective interventions. Adequate provisions of calories and protein have been shown to improve patient outcomes, and guidelines for the nutritional support of the critically ill patient are reviewed. However, there are no such specific guidelines for the critically ill patient with neurological injury. Patients with primary or secondary neurological disorders are frequently undernourished, while data suggest this population would benefit from early and adequate nutritional support, although comprehensive clinical evidence is lacking. We review the joint recommendations from the Society for Critical Care Medicine and the American Society for Parenteral and Enteral Nutrition, as they pertain to neurocritical care, and assess the recommendations for addressing nutrition in this patient population.

Hyperactivation of mammalian target of rapamycin complex 1 by HIV-1 is necessary for virion production and latent viral reactivation.

Generation of new HIV-1 virions requires the constant supply of proteins, nucleotides, and energy; however, it is not known which cellular pathways are perturbed and what molecular mechanisms are employed. We hypothesized that HIV-1 may regulate pathways that control synthesis of biomolecules in the cell. In this study, we provide evidence that HIV-1 hyperactivates mammalian target of rapamycin complex 1 (mTORC1), the central regulator of biosynthesis. Mechanistically, we identify the viral regulatory gene tat (transactivator) as being responsible for increasing mTORC1 activity in a PI3K-dependent manner. Furthermore, we show that hyperactivation of mTORC1 leads to activation of the enzyme, carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, dihydroorotase, and repression of initiation factor 4E-binding protein 1 activity. These are regulators of nucleotide biogenesis and protein translation, respectively. Moreover, we are able to replicate these results in HIV-1 latent cell line models. Finally, we show that inhibition of mTORC1 or PI3K inhibits viral replication and viral reactivation as a result of a decrease in biosynthesis. Overall, our study identifies a new avenue in HIV-1 biology that can lead to development of novel therapeutic targets.-Kumar, B., Arora, S., Ahmed, S., Banerjea, A. C. Hyperactivation of mammalian target of rapamycin complex 1 by HIV-1 is necessary for virion production and latent viral reactivation.

A Scheduling Model of Household Application with a Battery Storage System Based on Charge/Discharge Characteristics of Lithium-ion Battery

Due to over-consumption of fossil fuel and aggravation of greenhouse effects, renewable power system is one of the viable solutions for household application. Lithium-ion batteries are widely used for energy storage and constant energy supply for the excellent electrochemical performances. This work demonstrates a stand-alone renewable power system with battery storage for a household application. An integrated approach is proposed for optimal scheduling of household application, coordinated with the battery storage performances based onbattery charge/discharge characteristics. A mixed integer nonlinear programming (MINLP) model forscheduling of application and battery in household is established to minimize the levelized cost of energy (LCOE) of the system. Battery characteristics are optimized by considering the LCOE of the entire system. The strategies for application and battery scheduling in multiple periods are embedded into the model. Results show that the LCOE of the system obtained by the proposed model is reduced by optimizing the battery characteristics and multi-period scheduling schemes. The LCOE of the system depends intensively on the charge/discharge characteristics of battery. These results provide deep insights into design and operation of the battery storage system and the corresponding household power supply system.

The effect of AQP3 deficiency on fuel selection during a single bout of exhausting exercise.

Aquaporin-3 (AQP3) is an integral membrane protein that facilitates the transport of water and glycerol across cell membranes. However, the precise localization and function of AQP3 in skeletal muscles is currently unknown. In this study, we investigated the capacity of AQP3 knockout mice to perform a single bout of exhausting exercise and analyzed the parameters related to skeletal muscle energy metabolism during exhausting exercise. Mice were exposed to a single bout of treadmill running at a speed of 12m/min with 10° inclination until exhaustion, and sacrificed immediately, 24 h and 48h after exercise. Both immunohistochemistry and double immunofluorescence staining revealed that AQP3 is expressed at the cell surface with no evidence of colocalization with either AQP1 or AQP4 in hamstring skeletal muscles. When exposed to a single bout of exhaustive exercise, AQP3 knockout mice fatigued more easily with the average time to exhaustion shorter than the wild-type mice. After exhausting exercise, plasma glucose, muscle glycogen, muscle triglyceride, and muscle free fatty acid levels decreased compared with the values before exercise in both AQP3 knockout and wild-type mice. However, muscle glycerol concentration after exercise decreased in the wild-type mice, but rather increased in AQP3 knockout mice. These findings suggest that decreased glycerol efflux from the skeletal muscles in AQP3 knockout mice may result in low exercise capacity, presumably due to the limitations in the constant energy supply through hepatic gluconeogenesis from glycerol during the prolonged endurance exercise.

Adiponectin Inhibits Nutrient Transporters and Promotes Apoptosis in Human Villous Cytotrophoblasts: Involvement in the Control of Fetal Growth.

The placenta exchanges nutrients between the mother and the fetus and requires a constant abundant energy supply. Adiponectin (a cytokine produced primarily by adipose tissue) controls glucose and lipid homeostasis. It is well-known that maternal serum adiponectin levels are inversely related to birth weight, suggesting that adiponectin has a negative effect on fetal growth. This effect appears to be related to the control of nutrient transporters in human placenta. However, the underlying molecular mechanisms have not yet been characterized. In the present work, we studied adiponectin's direct effect on human primary cytotrophoblasts from first-trimester placenta. Our result showed that in placental cells, adiponectin 1) inhibits the expression of the major glucose transporters (GLUT1 and GLUT12) and sodium-coupled neutral amino acid transporters (SNAT1, SNAT2, and SNAT4), 2) enhances total ATP production but decreases lactate production, 3) inhibits mitochondrial biogenesis and function, and 4) stimulates cell death by enhancing the expression of the pro-apoptotic B-cell lymphoma-2 (BCL-2)-associated X protein (BAX) and tumor protein P53 (TP53) gene expression and inducing the caspase activity. Small-interfering RNA mediating the down-regulation of adiponectin receptors (ADIPOR1 and ADIPOR2) was used to demonstrate that adiponectin effects on placental nutrient transport and apoptosis seemed to be essentially mediated by these specific receptors. Taken as a whole, these results strongly suggest that adiponectin regulates human placental function by limiting nutrient transporter expression and inducing apoptosis. These findings may help us to better understand adiponectin's role in placental pathologies such as intrauterine growth restriction, which is characterized by fetal weight loss and drastic apoptosis of placental cells.

Cancer Metabolism: A Modeling Perspective.

Tumor cells alter their metabolism to maintain unregulated cellular proliferation and survival, but this transformation leaves them reliant on constant supply of nutrients and energy. In addition to the widely studied dysregulated glucose metabolism to fuel tumor cell growth, accumulating evidences suggest that utilization of amino acids and lipids contributes significantly to cancer cell metabolism. Also recent progresses in our understanding of carcinogenesis have revealed that cancer is a complex disease and cannot be understood through simple investigation of genetic mutations of cancerous cells. Cancer cells present in complex tumor tissues communicate with the surrounding microenvironment and develop traits which promote their growth, survival, and metastasis. Decoding the full scope and targeting dysregulated metabolic pathways that support neoplastic transformations and their preservation requires both the advancement of experimental technologies for more comprehensive measurement of omics as well as the advancement of robust computational methods for accurate analysis of the generated data. Here, we review cancer-associated reprogramming of metabolism and highlight the capability of genome-scale metabolic modeling approaches in perceiving a system-level perspective of cancer metabolism and in detecting novel selective drug targets.

Decreased PCSK9 expression in human hepatocellular carcinoma.

BackgroundThe management of hepatocellular carcinoma (HCC) is limited by the lack of adequate screening biomarkers and chemotherapy. In response, there has been much interest in tumor metabolism as a therapeutic target. PCSK9 stimulates internalization of the LDL-receptor, decreases cholesterol uptake into hepatocytes and affects liver regeneration. Thus, we investigated whether PCSK9 expression is altered in HCC, influencing its ability to harness cholesterol metabolism.MethodsThirty-nine patients undergoing partial hepatectomy or liver transplantation for HCC were consented for use of HCC tissue to construct a tissue microarray (TMA). The TMA was immunostained for PCSK9. Imagescope software was used to objectively determine staining, and assess for pathological and clinical correlations. PCSK9 and LDL receptor mRNA levels in flash-frozen HCC and adjacent liver tissue were determined by quantitative RT-PCR. Serum PCSK9 levels were determined by ELISA.ResultsBy immunohistochemistry, there was significantly lower expression of PCSK9 in HCC as compared to adjacent cirrhosis (p-value < 0.0001, wilcoxon signed-rank test). Significantly greater staining of PCSK9 was present in cirrhosis compared to HCC (p value <0.0001), and positivity (percentage of positive cells) was significantly greater in cirrhosis compared to HCC (p-value < 0.0001). Conversely, significantly higher expression of LDL-R was present in HCC as compared to the adjacent cirrhosis (p-value < 0.0001). There was no significant correlation of PCSK9 staining with grade of tumor, but there were significant correlations between PCSK9 staining and stage of fibrosis, according to spearman correlation test.PCSK9 mRNA levels were relatively less abundant within HCC compared to adjacent liver tissue (p-value =0.08) and normal control tissue (p-value =0.02). In contrast, serum PCSK9 levels were significantly increased among patients with HCC compared to those with chronic liver disease without HCC (p-value =0.029). LDL receptor mRNA was consistantly greater in HCC when compared to normal control tissue (p-value = 0.06) and, in general, was significantly greater in HCC when compared to adjacent liver (p-value = 0.04).ConclusionsThe decreased expression of PCSK9 and conversely increased LDL-R expression in HCC suggests that HCC modulates its local microenvironment to enable a constant energy supply. Larger-scale studies should be conducted to determine whether PCSK9 could be a therapeutic target for HCC.

THERMOMECHANICAL PUMP WITH THE USE OF LOW GRADE THERMAL ENERGY

The paper investigates the transformation of thermal energy to mechanical work on pumping of liquid at steam formation in narrow vertical channels. Feature of boiling up of liquid in narrow channels is formation of the steam shells which are completely blocking the cross section of the channel and pushing out liquid from it. There is a fluctuation mode of vaporizing and condensation processes at a constant supply of thermal energy. The model of rod emission is used for the description of that processes. This paper carries out the pilot studies of pressure variation in the channel during the operation of the mechanical heat pump and experimentally defines the dependences of flow rate of liquid on its temperature, the input power and pressure. The physical model of pump operation is developed, its characteristics are constructed. The thermomechanical pump can find application for increase of technological process efficiency in those areas of equipment where pumping of liquid with rather small expense is necessary and there is a large number of waste thermal energy.

Transient assembly of active materials fueled by a chemical reaction.

Fuel-driven self-assembly of actin filaments and microtubules is a key component of cellular organization. Continuous energy supply maintains these transient biomolecular assemblies far from thermodynamic equilibrium, unlike typical synthetic systems that spontaneously assemble at thermodynamic equilibrium. Here, we report the transient self-assembly of synthetic molecules into active materials, driven by the consumption of a chemical fuel. In these materials, reaction rates and fuel levels, instead of equilibrium composition, determine properties such as lifetime, stiffness, and self-regeneration capability. Fibers exhibit strongly nonlinear behavior including stochastic collapse and simultaneous growth and shrinkage, reminiscent of microtubule dynamics.

Nonequilibrium transient self-assembly

Chemistry In biology, the constant supply of energy can drive a system to be far from its equilibrium conditions and allow for useful work to be done. In contrast, in most synthetic systems, there is a drive toward lower energy states. Boekhoven et al. made a molecule that can switch between a nonassociating state and an associating state through the addition of a chemical fuel (see the Perspective by Van der Zwagg and Meijer). The lifetime, stiffness, and regenerative behavior of the self-assembled state could be controlled and tuned by the kinetics of fuel conversion. Science , this issue p. [1075][1]; see also p. [1056][2] [1]: /lookup/doi/10.1126/science.aac6103 [2]: /lookup/doi/10.1126/science.aad0194

Sizing of a Domestic Hot Water Heating and Storage System for Short Operating Cycles - A Theoretical Approach

A methodology for the sizing of domestic hot water heating and storage systems is defined, by assuming an extreme operating condition cycle composed of only two parts, a water consumption period and a system repositioning period. In both parts to respond to the extreme hot water demanding conditions, the heating is always on. The subsequent exergy analysis of this domestic hot water production system compares the irreversibility and the exergy efficiency of the water storage and the tankless situation. To carry out such analysis, some basic assumptions were made: a constant temperature heat source, a short duration operating cycle and a constant thermal energy supply. Under these circumstances it is shown that the hot water storage system leads to lower exergy losses while the tankless system is more exergy efficient, but requiring a higher instantaneous thermal power input. The use of the joule effect electricity, as the system heat source, be it a water storage one or a tankless one, maximizes the system irreversibility losses and minimizes the system exergy efficiency. The tankless system, with the joule effect electricity heat source is the worst situation.

Characterization of a Compact Organic Rankine Cycle Prototype for Low-grade Transient Solar Energy Conversion

Many people in rural regions of the worlddo not have access to electricity although they have abundant supplies of sunlight. An off-grid system to cheaply convert this solar energy into electricity could improve the lives of millions of families. Waste heat from high-concentration photovoltaic arrays and solar energy from evacuated tubecollectors are potential sources of abundant low-grade thermal energy. An Organic Rankine Cycle (ORC) is able to convert low-grade thermal energy into electricity at a relative low cost.While traditional ORCs rely on stable thermal energy inputs (i.e. geothermal energy), solar energy is not able to provide a constant supply of thermal energy. Understanding how transient solar fluctuations affect ORC performance is crucial to the development of high-performance, stable and stand-alone solar-driven ORC systems and further integration with heat storage units.In this work, an experimental ORC testbed was designed and fabricated for small-scale low-grade thermal energy utilization for transient characterization. Of particular interest in this work is the behavior of the ORC system as it approaches the operational limits. When the mass flow rate in the cycle is too high or the thermal energy input too low, the balance of the system is disturbed and strange oscillations are encountered. This work focuses on gaining a deep understanding of this abnormal behavior and itsinfluence on ORC performance. The physical phenomena that bring about these changes in an evaporator and their effect on ORC's moving components (i.e., diaphragm pump and scroll expander) are studied and characterized. A qualitative description of the phenomena is proposed and used to describe the changes within the cycle as a result of the imbalance. Once the individual processes in the oscillations are identified, quantitative analysis is carried out to better characterize the entire cycle. This characterization may be used to predict when the heat source conditions would lead to oscillations in ORCs and the magnitude of the reactions.These oscillations hinder the ORC performance and may even cause damage to the moving components under certain circumstances. Revealing the physical mechanismof oscillations helps attain advanceddesign and energy-efficient operation of ORCsunder transient thermal energy supplies, particularly solar. Cycle modifications such as heat storage units are also discussed to coping with transient solar energy inputs and night-time operation.

Development of a Communication Scheme for Wireless Power Applications With Moving Receivers

Commercial wireless power systems based on inductive coupling are gaining more popularity. These systems rely on a static alignment between a receiver and a transmitter coil for a certain amount of time. To make the technology more responsive when the device has to be charged while moving randomly in a larger area than the size of the transmitter coil, a dedicated communication scheme is required. In the presented solution, the receiver itself is equipped with a supercapacitor on board, in order to provide a constant energy supply to power the receiver functionality. The communication as described in this work is developed in order to meet the requirements of fast detection and quick charging. It has been implemented in the real-life configuration of a commercially available wireless mouse where the battery compartment was replaced with the receiver circuitry. Excellent functionality of the device was observed. It was demonstrated experimentally that the time it takes to force the transmitter in high-power mode equals 450 ms in case the receiver energy storage is completely drained, and on average, 50 ms when the receiver's microcontroller is still powered. These results contrast significantly with the well-known static receiver Qi-protocol, where these values rise to an average of respectively 2500 and 250 ms. The obtained timing values meet the requirements of rapidly collecting energy and a high degree of autonomy, even when the receiver structure is only a short amount of time above the transmitting structure.