Passive Storage Research Articles

A Methodology for the Enhancement of the Energy Flexibility and Contingency Response of a Building through Predictive Control of Passive and Active Storage

Optimal management of thermal energy storage in a building is essential to provide predictable energy flexibility to a smart grid. Active technologies such as Electric Thermal Storage (ETS) can assist in building heating load management and can complement the building’s passive thermal storage capacity. The presented paper outlines a methodology that utilizes the concept of Building Energy Flexibility Index (BEFI) and shows that implementing Model Predictive Control (MPC) with dedicated thermal storage can provide predictable energy flexibility to the grid during critical times. When the utility notifies the customer 12 h before a Demand Response (DR) event, a BEFI up to 65 kW (100% reduction) can be achieved. A dynamic rate structure as the objective function is shown to be successful in reducing the peak demand, while a greater reduction in energy consumption in a 24-hour period is seen with a rate structure with a demand charge. Contingency reserve participation was also studied and strategies included reducing the zone temperature setpoint by 2∘C for 3 h or using the stored thermal energy by discharging the device for 3 h. Favourable results were found for both options, where a BEFI of up to 47 kW (96%) is achieved. The proposed methodology for modeling and evaluation of control strategies is suitable for other similar convectively conditioned buildings equipped with active and passive storage.

The active storage machine (ASM) allows detecting traces of corneal refractive surgery: case report

AbstractPurposeThe detection and selection of corneas operated on for refractive surgery (LASIK or photorefractive keratectomy (PKR) by excimer) will become a major concern for eye banks in the coming years because this surgery is often forgotten during the interview with the deceased's relatives. Passive storage in organoculture (OC) prevents the detection of the traces of this surgery because of stromal edema making the cornea less transparent and wrinkled. On the other hand, the active storage machine (ASM) restores intraocular pressure, restores the cornea to its original shape, respects transparency and incorporates non‐invasive controls. It is, therefore, likely to facilitate the detection of refractive surgeries. We present here the case of 2 corneas operated on with PKR and stored successively in OC and ASM.MethodsThe 2 corneas of a 49‐year‐old donor operated 20 years earlier by PKR for ‐2 and ‐3 diopters myopia were stored in OC for 14 days and then placed in ASM for 48 hr. Transparency (transparometer, BiiGC), thickness map and OCT topography (Casia 1, Tomey) were performed under the 2 storage conditions. At the end of the observation, histology and electron microscopy were performed.ResultsTraces of PKR remained unnoticed in OC while they were evident in ASM: central epithelial anomaly, central thinning and flattening of central keratometry were found respectively in transparometry, pachymetry map and OCT topography. Histology and ultrastructure confirmed the absence of Bowman's membrane, pathognomonic of PRK.ConclusionsBy placing the cornea under physiological conditions, and in particular by triggering its deswelling thanks to the intraocular pressure and by restoring its natural curvature, the ASM should allow effective detection of refractive surgery traces.

Analysis of phase change materials for regulating the thermal environment of greenhouses in different climatic conditions in Highland areas

Phase change materials have good peak-shaving and valley-filling effects, which are effective for improving the thermal environment of passive thermal storage buildings. In this paper, phase change materials were applied to a solar greenhouse in the plateau area, and the indoor temperature is measured and analyzed under different meteorological conditions. It was concluded that when phase change materials were applied in the central region of Yunnan, where the temperature difference between day and night was large, it had a significant improvement effect on the thermal environment inside the solar greenhouse. The average outdoor air temperature, the maximum outdoor temperature difference between day and night, and solar radiation were the main factors affecting the temperature in the greenhouse. By analyzing and evaluating the effect of using phase change materials in solar greenhouses under different outdoor climate conditions, the advantages and limitations of using phase change greenhouses in different areas of the plateau were discussed.

Development of energy-saving manipulator using passive storage element and variable center of gravity mechanism

Development of energy-saving manipulator using passive storage element and variable center of gravity mechanism

An Abstract Machine Approach to Preserving Digital Information

Preserving digital information for a very long time is difficult even when using a durable passive storage medium such as photographic film stored under the right conditions. On film one can combine analog descriptions, i.e. visual and thus human-readable text and diagrams, with encoded digital information. After hundreds of years, however, the formats used to represent and encode this information may have been forgotten, and any surviving source code may not simply be compiled and run. Explaining how to interpret data stored in a complex format runs the risks both of errors made today and of future misunderstandings. We present a solution based on (1) a very simple abstract machine, (2) independent, technology-neutral descriptions of the machine, preserved in analog form and aimed at future programmers and mathematicians, respectively, and (3) a C compiler targeting this machine. Currently, our toolset supports storing and retrieving data in the formats JPEG, TIFF and PDF/A, but other formats can be easily be added by adapting existing C programs for processing these formats. Binaries for the abstract machine are preserved alongside the digital information and the machine descriptions so that future generations can decode and present the information simply by implementing this machine.

Thermal and energetic behaviour of solid-solid-liquid phase change materials storage unit: Experimental and numerical comparative study of the top, bottom and horizontal configurations

Thermal energy storage technology with Phase Change Materials (PCM) is an attractive option to optimise energy resources and to recover and promote excess heat. The phase change behaviour of PCM requires advanced research to understand and better control the thermal energy storage using PCM, which is a crucial step to develop a powerful latent storage system. This paper aims to analyse the multiphysics phenomena of three regenerator configurations, horizontal case and two injection direction of Heat Transfer Fluid (HTF): top and bottom in vertical case. The study is done for the charge and discharge cycles of the solid-solid and solid-liquid phase transitions of PCM. First, the temperature dependence of the thermal and physical properties of paraffin as PCM is characterised. Second, an experimental study of an annular latent storage system was carried out. Also, an experimental mesh method was introduced to compare the energy behaviour of the three cases. Third, a numerical analysis of the experimental storage unit with low thermal diffusion is performed. The experimental results are confronted with the numerical results obtained with ANSYS Fluent and COMSOL Multiphysics commercial software. Last, the three configurations are compared to a reference case without gravitational field. The results show that specific mechanisms control the thermal and energetic behaviour of the regenerator. Furthermore, several parameters, such as storage density, distribution of energy storage rate in the different regenerator components (PCM, HTF, and heat exchanger), were analysed. Altogether, the results supply important information to understand the dynamics of passive storage systems.

HM$^4$: Hidden Markov Model With Memory Management for Visual Place Recognition

Visual placerecognition needs to be robust against appearance variability due to natural and man-made causes. Training data collection should thus be an ongoing process to allow continuous appearance changes to be recorded. However, this creates an unboundedly-growing database that poses time and memory scalability challenges for place recognition methods. To tackle the scalability issue for visual place recognition in autonomous driving, we develop a Hidden Markov Model approach with a two-tiered memory management. Our algorithm, dubbed HM <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> , exploits temporal look-ahead to transfer promising candidate images between passive storage and active memory when needed. The inference process takes into account both promising images and a coarse representations of the full database. We show that this allows constant time and space inference for a fixed coverage area. The coarse representations can also be updated incrementally to absorb new data. To further reduce the memory requirements, we derive a compact image representation inspired by Locality Sensitive Hashing (LSH). Through experiments on real world data, we demonstrate the excellent scalability and accuracy of the approach under appearance changes and provide comparisons against state-of-the-art techniques.

Reduced-order models for assessing demand response with heat pumps – Insights from the German energy system

Heat pumps are regarded as one promising option for Demand Response (DR) in renewable-dominated energy systems. By activating the structural thermal mass of buildings, power consumption of heat pumps can be decoupled from heat demand. Assessing the system-wide DR potential from heat pumps requires adequate models to account for the thermal response of the building stock to flexible operation. In this study, reduced-order thermal response models of twelve representative German building types in three insulation states are provided based on grey-box modeling. The identified models reveal a good compromise between accuracy of the simulated indoor temperature (RMSE of on average 0.6 °C) and computational cost (acceleration by factor 250) compared to the complex building simulation software TRNSYS. Furthermore, these reduced-order models are employed in a case study to estimate the technical DR potential of heat pumps by passive storage at specified ambient conditions. Extrapolated to the future stock of German single family houses, the maximum shiftable heat pump load adds up to 57 GWel. The structural thermal mass of the building stock enables maximal 300 GWhel of electrical energy to be discharged at a very cold winter day and 185 GWhel to be charged at milder temperatures.

Energy flexibility and shiftable heating power of building components and technologies

PurposeThe paper aims to clarify the relationship between energy flexibility and building components and technologies. It determines the energy flexibility potential of buildings in relation to their physical characteristics and heat supply systems with respect to external boundary conditions.Design/methodology/approachThe emphasis of the evaluation is based on the timing and the amount of shiftable and storable thermal loads in buildings under defined indoor thermal comfort conditions. Dynamic building simulation is used to evaluate the potential of selected building characteristics to shift heating loads away from peak demand periods. Insights on the energy flexibility potential of individual technologies are gained by examining the thermal behaviour of single-zone simulation models as different input parameters are varied. For this purpose, parameters such as envelope qualities, construction materials, control systems for heating are modified.FindingsThe paper provides a comprehensive understanding of the influence of the different building parameters and their variations on their energy shifting potential under “laboratory conditions” with steady boundaries. It suggests that the investigated boundary conditions such as outside temperature, infiltration, envelope quality and user behaviour, which influence the heating load of a building, also influence the resulting potential for energy flexibility. The findings show that the combination of a slowly reacting heat transfer system, such as concrete core activation and a readily available storage mass in the room, and a high insulation standard proved to have a high potential to shift heating loads.Originality/valueIn this paper, energy-flexible components were evaluated in a steady-state simulation approach. Outside temperature, solar irradiation and internal loads over the simulation duration were set constant over time to provide laboratory conditions for the potential analysis. On the basis of both duration and performance of the load shifting or storage event, the components were then quantified in a parametric simulation. The determined energy flexibility is directly related to the power of the heating, cooling, hot water and ventilation system, which can be switched on or off. In general, it can be seen that high power (high loads) demand usually can be switched on and off for a short duration, and low power demand usually for a longer duration. The investigated boundary conditions such as outside temperature, infiltration, envelope quality and user behaviour, which influence the load of a building, also influence the resulting potential for energy flexibility. Higher insulation standards, for example, lead to lower loads that can be switched on or off, but increase the duration of the event (flexibility time). So that, in particular, the shiftable load potential is low but results in a long switch-off duration. Furthermore, passive storage potential in buildings like the storage mass inside the room and the type of heat/cooling transfer system can affect the flexibility potential by more than three times. Especially the combination of a high storage mass and a concrete core heat transfer system can significantly increase the flexibility.

Effect of passive modified atmosphere storage incorporated with 1-MCP on quality of asparagus spears during cold storage

Effect of passive modified atmosphere storage incorporated with 1-MCP on quality of asparagus spears during cold storage

A Hybrid PV-Battery/Supercapacitor System and a Basic Active Power Control Proposal in MATLAB/Simulink

An increase in the integration of renewable energy generation worldwide brings along some challenges to energy systems. Energy systems need to be regulated following grid codes for the grid stability and efficiency of renewable energy utilization. The main problems that are on the active side can be caused by excessive power generation or unregulated energy generation, such as a partially cloudy day. The main problems on the load side can be caused by excessive or unregulated energy demand or nonlinear loads which deteriorate the power quality of the energy networks. This study focuses on the energy generation side as active power control. In this study, the benefits of supercapacitor use in a hybrid storage system are investigated and analyzed. A hybrid system in which photovoltaic powered and stored the energy in battery and supercapacitor are proposed in this study to solving the main problems in two sides. The supercapacitor model, photovoltaic model, and the proposed hybrid system are designed in MATLAB/Simulink for 6 kW rated power. Also, a new topology is proposed to increase the energy storage with supercapacitors for a passive storage system. The instantaneous peak currents energy is aimed to store in supercapacitors temporarily with this topology. The main advantages of this topology are voltage stabilization in two sides by the supercapacitors and a limitation of the battery load, which directly results in longer battery life and decreases the system cost. The simulation results are investigated for this topology.

Deshidratador solar híbrido para el secado de plátano

In this work the design of a solar dryer for the dehydration of fruits is presented. Banana is used as raw material for analysis and evaluation purposes. The system is supplied with solar energy in the form of (photovoltaic) PV and (photothermic) PT. The PV part of the dehydrator consists of a solar panel, whose energy supplies electrical resistances to increase the temperature, also feeding a forced air convection system which is carried out with a pair of fans that are at the entrance and exit of the dehydrator, also a control and measurement system. In the other side the PT part consist in a passive storage system of heat direct and indirect catchment of radiation. For the development of the solar dryer it is necessary to take into account certain parameters such as: weather conditions (solar radiation, ambient temperature and wind speed), thermal conductivity, temperature and properties of the components.

Experimental and numerical investigation on dodecane/expanded graphite shape-stabilized phase change material for cold energy storage

Using cold latent heat thermal energy storage (LHTES) in cold chain logistics can improve the energy efficiency. In this study, a shape-stabilized phase change material (PCM) with dodecane as PCM and expanded graphite (EG) as skeleton was developed firstly. The optimal content of EG in composite was confirmed as 16 wt% by heat treatment and DSC testing. The DSC testing results show that dodecane/EG shape-stabilized PCM has a phase change temperature of −9.67 °C and latent heat of 151.7 J/g. The microstructure of the dodecane/EG was characterized by SEM, FT-IR and specific surface area analyzer, and the results show that the dodecane was uniformly stuffed in the pore structure of EG under physical action. Thermal conductivity of the dodecane/EG is 15 times higher than that of dodecane. And the thermal conductivity enhancement of the composite PCM was also verified by the thermal performance test. Moreover, a numerical model of passive storage system with the dodecane/EG PCM was established and the simulation results are highly matched with the experimental result. In conclusion, the prepared dodecane/EG with noticeable thermal permeance and form stability and can be further applied in cold LHTES.

Efficient Generation of Stable Sm2+ in Nanocrystalline BaLiF3:Sm3+ by UV- and X-Irradiation

In recent decades, storage phosphors have found widespread applications in the fields of dosimetry and computed radiography due to their impressive properties including large dynamic range and passive storage mode. Despite this success, further development of highly efficient X-ray and UV sensitive luminescent materials is still desirable, in par-ticular for applications in dosimetry. In this Article we report X-ray and UV storage properties of nanocrystalline Ba-LiF3 doped with Sm3+. Nanocrystalline BaLiF3:Sm3+ was prepared mechanochemically by ball milling and the resulting product was characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The re-sponse of the phosphor to X-ray and UV radiation was investigated by measuring room temperature photolumines-cence spectra before and after irradiation for a wide range of doses. The lifetime of the Sm2+ emission at 694 nm was determined for both the X-ray and UV irradiated powder samples. The results indicate a potential fo...

University Library as Knowledge Management Centre

The article discusses the transition to a new stage of civilization, the knowledge society. In the modern world, knowledge is one of the major socio-economic resources for both the individual and the state. Accordingly, the educational strategy of any higher educational institution should be refocused to ensure smooth transition from the traditional model to innovative in order to prepare the modern student for a life in the society where innovation and intellectual resources play the major role. The modern library can act as a control centre of knowledge, integrate with the world information resources and mediate for the user in global information space using the tools and mechanisms of the electronic library. In this regard, the e-library becomes a knowledge management centre focused on the development and maximum use of intellectual potential of library for the purpose of preservation, reproduction, building up and broadcasting of knowledge. The article analyses the opportunities which are given by electronic library for the University.The authors constructed the scheme of interrelation of knowledge and information resources. The article considers the concept of proactive electronic library of the University as a system of information service of readers, the main purpose of which is to provide resources in any form and on any carrier using the classical and network forms of services based on the advanced inquiry services. The authors constructed the model of proactive University library, which is a complex system, incorporating elements of various properties and complexity. The proactive electronic library itself searches for information corresponding to the information needs of the user, without waiting for his request; that can influence the development of his information needs. Thus, the library transforms from a passive storage of information into an interaction partner. Information is automatically selected for the user, relevant to his educational and scientific interests, hobbies and preferred leisure.

High-Frequency Single-Switch ZVS Gate Driver Based on a Class $\Phi _2$ Resonant Inverter

This paper introduces a new type of switched-mode gate driver, which is capable of operating at high frequencies. This topology satisfies requirements of small passive storage components, low-voltage stress, and high design flexibility. Most popular gate-drive circuits require at least two transistors. The proposed circuit has only a single transistor and is suitable for operation at switching frequencies on the order of several megahertz. The output voltage of the gate driver is a quasi-rectangular waveform shaped by a resonant network to produce the desired gate–source voltage waveform. A detailed steady-state operation of the proposed gate driver is discussed. The power-loss analysis and design procedure are presented. Experimental results are given to verify the presented analytical approach. A laboratory prototype of the gate driver is designed, built, and tested at a switching frequency of 20 MHz.

Transcriptional Regulation of Zinc Transporters in Human Osteogenic Sarcoma (Saos-2) Cells to Zinc Supplementation and Zinc Depletion.

Bone is a passive storage organ for zinc, which contains about 30% of the total body zinc. However, during extreme zinc deficiency, only a small fraction of zinc is released in contrast to other tissues where zinc is released like monocytes or conserved, e.g., skeletal muscle. Zinc plays an important role in bone tissue remodeling. Zinc homeostasis is regulated by several zinc transporters (ZnTs) and importers (ZIPs), but their expression dynamics concerning zinc status of bone cells is not well understood. The study aimed to elucidate the effects of zinc supplementation and depletion on the transcript levels of various zinc transporters. Saos-2, a human osteoblastic cell line, was used as representative bone tissue. Zinc sulfate was used for simulating sufficient zinc status whereas TPEN, a zinc chelator, was used to simulate zinc-deficient state. Expression of various transcripts was measured by qRT-PCR. Subcellular localization of ZnT-1 was carried out by immunofluorescent microscopy, and Western Blotting was carried out to measure the expression of ZnT-1 at the protein level. Among the export transporters the transcript levels of MT, ZnT-1 showed higher levels in zinc sufficient and lower levels in TPEN treated cells. Expression of ZnT-4 was decreased under both the conditions. ZIP-6 and ZIP-13 were downregulated in zinc sufficiency, and ZIP-10 upregulated probably to prevent an excess zinc accumulation in bone cells. Further, ZnT-1 was found to be localized in the nuclear region of SaOS-2 cells. ZnT-1, ZnT-4, ZIP-6, ZIP-11, ZIP-10, and ZIP-13 along with MT may be responsible for maintaining bone zinc homeostasis.

Probing the limits of activity-silent non-conscious working memory

Two types of working memory (WM) have recently been proposed: (i) active WM, relying on sustained neural firing, and (ii) activity-silent WM, for which firing returns to baseline, yet memories may be retained by short-term synaptic changes. Activity-silent WM in particular might also underlie the recently discovered phenomenon of non-conscious WM, which permits even subliminal stimuli to be stored for several seconds. However, whether both states support identical forms of information processing is unknown. Theory predicts that activity-silent states are confined to passive storage and cannot operate on stored information. To determine whether an explicit reactivation is required before the manipulation of information in WM, we evaluated whether participants could mentally rotate brief visual stimuli of variable subjective visibility. Behaviorally, even for unseen targets, subjects reported the rotated location above chance after several seconds. As predicted, however, at the time of mental rotation, such blindsight performance was accompanied by (i) neural signatures of consciousness in the form of a sustained desynchronization in alpha/beta frequency and (ii) a reactivation of the memorized information as indicated by decodable representations of participants' guess and response. Our findings challenge the concept of genuine non-conscious "working" memory, argue that activity-silent states merely support passive short-term memory, and provide a cautionary note for purely behavioral studies of non-conscious information processing.

Power Frequency Harmonic Reduction and its Redistribution for Improved Filter Design in Current-Fed Switched Inverter

Due to the pulsating power at the inverter output terminals, the passive storage elements of the boost stage of the current-fed switched inverter (CFSI) contain a power frequency harmonic component (100 Hz), apart from dc and switching frequency components. In prior designs, the second harmonic component is suppressed by increasing the size of the input filter inductor and capacitor or by using additional circuits. This paper presents a complete characterization of a control-based approach to suppress the power frequency harmonic component in the input inductor current of a CFSI. It also presents a comprehensive characterization of the harmonic power redistribution. Using the proposed approach, it is demonstrated that the inductor value of a CFSI is reduced by 61% for the same peak-to-peak ripple. This leads to an improvement in the conversion ratio, efficiency, and power density of the overall converter. A SiC MOSFET-based CFSI with 75-kHz switching frequency is used to verify the proposed design philosophy.

Aftertreatment Protocols for Catalyst Characterization and Performance Evaluation: Low-Temperature Oxidation, Storage, Three-Way, and NH3-SCR Catalyst Test Protocols

A set of standardized and realistic aftertreatment catalyst test protocols have been developed by the Advanced Combustion and Emission Control Technical Team in support of the U.S. DRIVE Partnership. The protocols are intended to accelerate the pace of aftertreatment catalyst innovation by enabling the accurate evaluation and comparison of aftertreatment catalyst performance data from various testing and research facilities to maximize the impact of discovery-phase research occurring across the nation. The protocols address a need identified by the Partnership’s industry partners for consistent and accurate metrics for aftertreatment catalyst evaluation and comparison. The protocols consist of a set of standardized requirements and test procedures that sufficiently capture the performance capability of a catalyst technology in a manner that is adaptable in various laboratories. The protocols provide a detailed description of the necessary reactor system, the steps for achieving a desired aged state of the catalyst, all necessary sample pretreatments to be performed prior to testing, and realistic test conditions for evaluating performance. This article details four low-temperature catalyst test protocols applicable to (1) oxidation catalysts, (2) passive storage (and release) catalysts, (3) three-way catalysts, and (4) NH3-SCR catalysts. The catalyst test protocol descriptions are presented in five (5) sections: protocol general guidelines and the four individual catalyst test protocol descriptions. The general guidelines plus the individual protocol description forms the complete low-temperature catalyst test protocol for the application.