Buffer Space Research Articles

Mechanochemical regulation of microcrystalline in coal-derived disordered carbon for improved sodium storage: Metamorphic grade

Coals are common precursors of the disordered carbon anodes for sodium ion batteries. In order to hinder the long-range ordered development of coal precursors during thermal conversion, the acid reagents and calcination under air atmosphere have been adopted in the pre-oxidation procedure, not in accordance with the demand of green energy storage. Herein, the mechanochemical pretreatment was employed to break the aromatic structures and generate the edge defects and oxygen functional groups on the coal surface, which would suppress the long-range ordered tendency and promote the introduction of nitrogen heteroatoms during following calcination. With the increasing metamorphic grades, the molecular rigidity of coal precursors increases owing to more highly polycondensed aromatic structures and less interior buffer space. The aromatic structures in the highest-ranked anthracite are broken most heavily during the mechanochemical process. Thus the nitrogen-doped anthracite-based carbon materials have the most disordered carbon structures and deliver a high reversible capacity of 323 mA h g−1 under 0.03 A/g after 90 cycles. This work provides a facile and green solution to fabricate the highly disordered carbon anodes with low cost and high performance from the industrial raw materials.

Flower-like carbon spheres formed by self-assembly of nitrogen-doped porous nanoribbons to boost SnS2 nanosheets for advanced lithium storage

SnS2 is a two-dimensional layered material with high theoretical capacity, but its further application in lithium-ion batteries is limited by problems such as low intrinsic conductivity and dramatic volume expansion during lithiation process. Therefore, SnS2 nanosheets were designed to anchor in the interlayer nanospaces of flower-like carbon spheres self-assembled from nitrogen-doped porous carbon nanoribbons (SnS2/N-FC). Nitrogen-doped porous nanoribbons facilitated the uniform distribution of SnS2 nanosheets in the interlayer nanospaces of the flower-like carbon spheres, establishing a face-to-face interaction with the nanoribbons and the SnS2 nanosheets. This composite structure enhances the transfer of electrons between the components. In addition, the integration of spherical flower-like electrodes with the reserved interlayer nanospaces provided a buffering space for volume expansion which ensured an even distribution of mechanical stress. As a result, SnS2/N-FC exhibited a high reversible specific capacity of 1322.3 mAh g−1 after 200 cycles at 0.1 A g−1, with the capacity kept growing to 1329.4 mAh g−1 after 1000 cycles at 1 A g−1. This study introduces a novel approach for the design of anode materials which demonstrate excellent lithium storage.

Multi-AGV Scheduling under Limited Buffer Capacity and Battery Charging Using Simulation Techniques

In recent years, automated guided vehicles (AGVs) have been widely adopted to automate material handling procedures in manufacturing shopfloors and distribution centers. AGV scheduling is the procedure of allocating a transportation task to an AGV, which has large impacts on the efficiency of an AGV system with multiple AGVs. In order to optimize the operations of multi-AGV systems, AGV scheduling decisions should be made with consideration of practical issues such as buffer space limitations and battery charging. However, previous studies have often overlooked those issues. To fill this gap, this paper proposes a simulation-based multi-AGV scheduling procedure for practical shopfloors with limited buffer capacity and battery charging. Furthermore, we propose three kinds of rules: job selection rules, AGV selection rules, and charging station selection rules, for AGV scheduling in practical shopfloors. The performance of the rules is evaluated through multi-scenario simulation experiments. The FlexSim software v.2022 is used to develop a simulation model for the experiments, and the experimental findings indicate that the job selection rules have larger impacts on the average waiting time than the other kinds of rules.

Rethinking the Healthcare Facilities: The Role of the Buffer Space.

A working group conducted a survey on the use of the principle of buffer space (BS), which in case of emergencies, could benefit healthcare settings. The aim of the preliminary investigation is to define new research lines in hospitals' functional design. The global experience of the COVID-19 pandemic highlighted challenges faced by hospitals when responding promptly to emergencies, including spatial reorganization and suspension of ordinary medical activities for ensuring adequate management of the emergency surge of patients. The group designed questionnaires to be administered to healthcare staff and healthcare designers aimed at understanding varied conceptions and features of BSs. Content across the two surveys overlapped significantly, allowing for direct comparisons of responses, while also including tailored questions in relation to the respective experience and skills of the two groups of respondents. 102 healthcare professionals and 56 designers took part to the survey. Analysis of the responses permitted for initial recommendations regarding BS typology including (a) proximity to the emergency department (ED), intensive care units (ICUs), and inpatient wards (IWs); (b) location within hospitals but separate from other medical areas; (c) need for independent access; (d) organizational and spatial features similar to ED, ICUs, and IWs; (e) existing as a fully flexible operational space; and (f) BS bed capacity to be approximately 12% of ED beds. Although the analysis is related to the Italian context, the expansion of this preliminary research to alternate healthcare facilities and geographic areas is necessary for reaching a wide consensus by different professionals on this field. It serves as a starting point for future investigations regarding the implementation of BS in hospital settings.

Amphisbaena: A Novel Persistent Buffer Management Strategy to Improve SMR Disk Performance

The explosive growth of massive data makes shingled magnetic recording (SMR) disks a promising candidate for balancing capacity and cost. SMR disks are typically configured with a persistent buffer to reduce the read–modify–write (RMW) overhead introduced by non-sequential writes. Traditional SMR zones-based persistent buffers are subject to sequential-write constraints, and frequent cleanups cause disk performance degradation. Conventional magnetic recording (CMR) zones with in-place update capabilities enable less frequent cleanups and are gradually being used to construct persistent buffers in certain SMR disks. However, existing CMR zones-based persistent buffer designs fail to accurately capture hot blocks with long update periods and are limited by an inflexible data layout, resulting in inefficient cleanups. To address the above issues, we propose a strategy called Amphisbaena. First, a two-phase data block classification method is proposed to capture frequently updated blocks. Then, a locality-aware buffer space management scheme is developed to dynamically manage blocks with different update frequencies. Finally, a latency-sensitive garbage collection policy based on the above is designed to mitigate the impact of cleanup on user requests. Experimental results show that Amphisbaena reduces latency by an average of 29.9% and the number of RMWs by an average of 37% compared to current state-of-the-art strategies.

Efficient Polytelluride Anchoring for Ultralong-Life Potassium Storage: Combined Physical Barrier and Chemisorption in Nanogrid-in-Nanofiber

HighlightsThe hierarchical nanogrid-in-nanofiber-structured dual-type carbon-confined CoTe2 nanodots (CoTe2@NC@NSPCNFs) were synthesized via facile templates and an electrospinning approach.Hierarchical nanogrid-in-nanofiber structure effectively suppresses the volume change of CoTe2 and the shuttle of potassium polytelluride (K-pTex) through robust physical restraint and strong chemisorption.CoTe2@NC@NSPCNFs hybrid achieves ultralong lifespan potassium-storage performance over 3500 cycles, and the deep mechanisms underlying the evolution, dissolution, and shuttle of K-pTex have been clearly revealed.

Graphene-wrapped Fe2TiO5 nanoparticles with enhanced performance as lithium-ion battery anode

Iron-titanium bimetallic oxide, Fe2TiO5 (FTO), is anticipated to exhibit superior electrochemical properties due to its high theoretical capacity. However, the practical large-scale utilization of FTO is severely hindered by its substantial capacity fading and subpar cycling performance. In this work, we propose a strategy to improve the electrochemical properties of FTO by carbon coating. To implement this strategy, we synthesize FTO nanoparticles (FTO NPs) coated with reduced graphene oxide (rGO) by a solvothermal method. When used as anode materials in lithium-ion batteries, FTO/rGO composite demonstrates a higher specific capacity (498.2 mAh g−1 after 100 cycles) than pristine FTO NPs, which is ascribed to the addition of rGO. The rGO with excellent conductivity facilitates efficient electron and ion transportation, and the composite structure of FTO NPs wrapped with rGO provides buffer space to alleviate the volume expansion during the charge/discharge process.

Deep neural network with fuzzy algorithm to improve power and traffic-aware reliable reactive routing

<span>In wireless networks, link breaks, and restricted resources create fundamental challenges for maintaining network applications. Several wireless network routing techniques concentrate on power efficiency to expand the network lifetime, but the traffic and reliability parameters are not the primary concern. Though, these techniques are not capable of dealing with the wireless network. Hence, this paper proposes deep neural network (DNN) with a fuzzy algorithm to improve power and traffic-aware reliable reactive routing (PTAR) in wireless networks. The wireless network is formed by clustering by the node power and selects the cluster head (CH) based on a fuzzy algorithm. The wireless node power level, node buffer space, and node reliability to consider the input parameters of the fuzzy system. Then thefuzzy algorithm gives the output for CH round length. This selected CH improves the node reliability, power efficiency with minimized network congestion. Then we use a DNN algorithm to choose an optimal relay by applying an adaptive load balance factor in the network. DNN is a machine learning algorithm, and it provides high accuracy. From the simulation results, the PTAR approach improves the network performance, such as packet received ratio, delay, residual energy, and routing overhead.</span>

Reduced graphene oxide-encaged submicron-silicon anode interfacially stabilized by Al2O3 nanoparticles for efficient lithium-ion batteries.

Silicon-carbon composites have been recognized as some of the most promising anode candidates for advancing new-generation lithium-ion batteries (LIBs). The development of high-efficiency silicon/graphene anodes through a simple and cost-effective preparation route is significant. Herein, by using micron silicon as raw material, we designed a mesoporous composite of silicon/alumina/reduced graphene oxide (Si/Al2O3/RGO) via a two-step ball milling combined annealing process. Commercial Al2O3 nanoparticles are introduced as an interlayer due to the toughening effect, while RGO nanosheets serve as a conductive and elastic coating to protect active submicron silicon particles during lithium alloying/dealloying reactions. Owing to the rational porous structure and dual protection strategy, the core/shell structured Si/Al2O3/RGO composite is efficient for Li+ storage and demonstrates improved electrical conductivity, accelerated charge transfer and electrolyte diffusion, and especially high structural stability upon charge/discharge cycling. As a consequence, Si/Al2O3/RGO yields a high discharge capacity of 852 mA h g-1 under a current density of 500 mA g-1 even after 200 cycles, exhibiting a high capacity retention of ∼85%. Besides, Si/Al2O3/RGO achieves excellent cycling reversibility and superb high-rate capability with a stable specific capacity of 405 mA h g-1 at 3000 mA g-1. Results demonstrate that the Al2O3 interlayer is synergistic with the indispensable RGO nanosheet shells, affording more buffer space for silicon cores to alleviate the mechanical expansion and thus stabilizing active silicon species during charge/discharge cycles. This work provides an alternative low-cost approach to achieving high-capacity silicon/carbon composites for high-performance LIBs.

Efficient electrocatalysts for biomass quasi-solid-state Li-O2 batteries: porous nanocages with nickel-cobalt-N/C active species

Ordered porous materials can offer more accessible catalytic sites and a large buffer space for discharge products, thus improving the cell performance. In the paper, a simple down-top solution-precipitation method...

Thermodynamic modelling and control strategy of smart grid thermal energy storage power station based on communication technology

As a modern power grid that integrates advanced communication technology, sensor measurement technology, and intelligent control technology, the smart grid has good economy, reliability, and stability. Building a strong smart grid has important strategic significance for developing the national economy and improving Comprehensive National Power. The balance of electricity supply and demand, as a physical feature of the power system, determines the energy matching relationship between generation and consumption. Unreasonable power generation may lead to unmet electricity demand, as well as excess electricity and waste of resources. The energy storage has solved the problem of imbalance between supply and demand in most environments. The energy storage equipment provides a buffer space for electric energy, effectively adjusts the time unevenness of power grid load, realizes peak shaving and valley filling, and reduces the operation cost of the power grid. Taking the aboveground energy storage power station as the research object, the 3-D unsteady model of the small and medium-sized compressed energy storage system was established by using the FLUENT simulation software, and the correctness was verified through experimental methods. The influence of different environmental temperatures, chamber inflation flow rate, the thermodynamic characteristics of the surface condition and working chamber of the and energy storage were studied. The results show that the environmental temperature and expansion flow of oil storage chamber have important effects on its thermodynamic characteristics, while the surface conditions of oil storage chamber wall have little effect on its thermodynamic characteristics.

A Thin, Stable, and Flexible Janus Lithium‐Textile Anode for Long‐Life and High‐Energy Lithium Metal Battery

AbstractEquipping thin lithium metal anodes (LMAs) in lithium metal batteries (LMBs) is essential to realize a high energy density of the battery. However, the cycling stability of thin LMAs, especially at high depth of discharge (DOD), is very poor. Here, the rapid preparation of stable and thin LMAs through selective wetting of molten lithium (Li) on a Janus structured conductive textile is reported, which yields a thin Li (∼3.0 mg cm−2) coating on one side of the conductive framework. This Janus Li‐textile composite anode not only significantly reduces the use of Li metal by 80% in comparison to the homogeneous composite anode, but also enhances the cycling stability via the Janus lithiophobic–lithiophilic framework and upper buffering space. At a high DOD of 75%, the Janus Li‐textile anode exhibits an ultralong cycle life over 3000 h. LMBs equipping with the Janus Li‐textile anode show an enhanced energy density by 30%, with a remarkable cycling life of 2000 cycles, and capacity retention of 99.94% per cycle.

Studying Degradation of Micro- and Nano-Scale Silicon in Si/ Rgo-Anode Materials for Lithium-Ion Batteries – Towards a Fair Comparison

An attractive approach to increase the Li+-storage capacity of anode materials in Lithium-ion batteries (LiBs), is to replace or combine the routinely-applied graphite (372 mAh g-1) with higher-capacity materials. Among others, silicon (Si) with a theoretical capacity of 3579 mAh g-1 is a promising candidate [1]. Silicon is not yet been used as an anode material in its pure form, due to its low conductivity and volume increase of up to 300 % during lithiation. This two-step expansion (1st: Si + 2 Li+ + 2 e- → SiLi2.0; 2nd: SiLi2.0 + 1.5 Li+ + 1.5 e- → SiLi3.5) is a source of mechanical stress that can ultimately lead to battery failure. Furthermore, the initial lithiation of crystalline silicon (c-Si + 3.5 Li+ + 3.5 e- → SiLi3.5) causes an amorphization of the pristine crystalline lattice. This structural change causes further degradation of the material, which can hardly be avoided [2].The main degradation mechanisms resulting from expansion and amorphization are I) The uncontrolled formation of a passivation layer due to the cyclic volume change taking place during (de-)lithiation, which leads to a continuous break-up and reformation of the solid electrolyte interphase (SEI). II) The pulverization of particles resulting in mechanical stress and the electrical isolation of particles or particle fragments delaminating from the electrode [3]. The first mechanism discussed is more dominant for nanometer scaled particles (nm-Si), while the second mechanism occurs mostly for particles in the micrometer range (µm-Si).Our approach combines, nm- or µm-sized Si particles with different matrix materials. By incorporating the particles into an either graphitic or soft carbon-like support, we aim to increase the conductivity of the electrode material and gain additional buffer space thereby reducing interparticle mechanical stress [4]. On the one hand, the systems of carbon-based anode materials are already well understood in terms of electrode composition, processing parameters, electrolyte compatibility, formation of a stable SEI and the resulting high cycling stability. On the other hand, the observed degradation mechanisms will occur with different predominance in different Si/C composites depending on the Si particle size and the chosen carbon matrix. However, the latter is not completely understood. We will address these issues by comparing different Si/C-composites consisting of nm-Si-particles or µm-Si particles in a reduced graphite oxide (rGO) matrix and in a graphite-matrix.Electrochemical methods, such as galvanostatic cycling, impedance spectroscopy and dq/dU-analysis in 2- and 3-electrode setups, were coupled with optical and spectroscopical techniques (e.g. XRD, FTIR, SEM) to trace back the electrochemically measurable degradation of the electrode to structural changes during formation and cycling. Particular attention was paid to the localization and analysis of defect areas with increased degradation by correlating the optical and spectroscopical results data with the lithiation and delithiation processes. Considering the different SoC levels, we can identify the ongoing aging of the different electrode materials. Based on this, we propose the use of soft carbon-like structures such as rGO as a matrix material for Si/C composites due to its higher cycling stability under the investigated conditions.

ZIF-67 derived material encapsulated V2O3 hollow sphere structure of Co-NC@V2O3-sp used as a positive electrode material for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries receive considerable attention for their high energy density, but their slow reaction kinetics and poor shuttle effects raise concerns. Here, synthesized V2O3 spheres were used as substrate templates, and ZIF-67 particles were grown on the surface of V2O3 by in-situ growth method. ZIF-67 was calcined at high temperature to form N-doped porous carbon attached to the surface of V2O3 spheres (Co-NC@V2O3-sp). The hollow structure of V2O3 spheres provided abundant buffer space for sulfur volume expansion and enhanced the stability of the battery cycle. In addition, the great pore volume and specific surface area resulted in abundant active physical and chemical sites, the strong chemical adsorption of V4+ effectively trapped polysulfides, and the cobalt nanoparticles on the surface effectively consolidated the active sites. The rapid transformation between shuttle effect and polysulfides were limited by physical coordination and chemisorption, respectively. Owing to this double synergistic effect, the prepared composites had an initial discharge capacity of 1483 mAh g−1 (0.1 C). The initial specific capacity reached 1002 mAh g−1 (0.5 C), and it achieved 645 mAh g−1 after 500 cycles. These results showed that Co-NC@V2O3-sp has high electrochemical function in Li-S batteries.

Residential Unit Design for Natural Ventilation in Tropical Multi-Family High-Rises With a Double-Loaded Corridor

This research investigates practical methods to improve the efficiency of natural ventilation in residential units of multi-family high-rises without additional areas. Typical studio- and one-bedroom-types of small units were redesigned using: 1) air post, 2) transom window, 3) buffer space with one corridor opening and 4) buffer space with two corridor openings. The simulation study using a CFD program to reveal that the indoor average air velocity coefficient (Cv ) in the best redesigned case (0.46) significantly improves from the base case (0.01). The paper demonstrates an example of application to an actual climate in Bangkok, Thailand. It was found that the proposed redesign using buffer spaces can considerably help upgrade the living conditions of the occupants in terms of both thermal comfort (24 hours vs. 0 hours in the comfort zone per day) and indoor air quality (24 hours vs. 8–17 hours that pass the minimum ventilation requirement per day) in the transitional month of February.

Intelligent Deep Learning and Softmax Routing for Energy-Efficient Wireless Sensor Networks in Public Space Design

The increasing usage of several nodes to transfer the massive volume of data to the remotes in wireless sensor networks is a challenging task to reduce the loss. The high volumes of data transmission in wireless sensor networks (WSN) can surpass their capacity, resulting in congestion, latency issues, and packet loss. However, computational intelligence (CI) models can aid in managing and creating intelligent networks in WSN. The WSN congestion issues result in information loss and increased energy usage. CI-based models have been used to resolve this issue, reducing the latency. This paper proposes SoftMax Routing with Deep Neural Network (SRDNN) for efficient routing in WSN. This will route the data packets by choosing the high energy and lower load. It consists of two parts, such as the construction of the routing path, which determines the residual energy of the node. It is analyzed using SoftMax routing to decide whether the node is efficient in energy. The route request and reply established various paths between the source and destination. The path with minimum buffer space and maximum bandwidth is chosen in the optimal routing. The simulation results under the metrics such as energy consumption, data loss rate, throughput, and delay show the proposed model performance.

Electronic States Tailoring and Pinning Effect Boost High-Power Sodium-Ion Storage of Oriented Hollow P2-Type Cathode Materials.

Fierce phase transformation and limited sodium ion diffusion dynamics are critical obstacles that hinder the practical energy storage applications of P2-type layered sodium transition metal oxides (NaxTMO2). Herein, a synergistic strategy of electronic state tailoring and pillar effect was carefully implemented by substituting divalent Mg2+ into Na0.67Ni0.33Mn0.67O2 material with unique oriented hollow rodlike structures. Mg2+substitution can not only facilitate the anionic oxygen redox reactions and electronic conductivity through increasing the electronic states at Femi energy but also act as pillars within TMO2 layers to alleviate the severe phase transformation to improve structure stability. Moreover, the oriented hollow structure incorporating sufficient buffer spaces and rationally exposed electrochemically active facets effectively alleviates the stresses induced by low volume changes of 8% and provides more open channels for Na+ ion diffusion without crossing multiple grain boundaries. Hence, the Na0.67Mg0.08Ni0.25Mn0.67O2 cathode showed a superior rate capability with high energy density and cycling stability for sodium-ion storage. The underlying mechanisms of these achievements were deciphered through diversified dynamic analysis and the first principle calculations, providing new insights into P2-type NaxTMO2 cathodes for the infinite prospect as an alternative to lithium-ion batteries.

Carbon-coated SnOx anchored on phosphorus-doped carbon framework as high performance anode of lithium-ion batteries

SnO2 has been recognized as one of the most potential anodes of lithium-ion batteries due to its high theoretical specific capacity, low cost, simple synthetic method, and environmental friendliness. However, the application of SnO2 is hindered owing to its huge volume expansion (∼300 %) and poor electronic conductivity. In this work, carbon-coated SnOx containing some SnO anchored on the phosphorus-doped carbon framework (SnOx/C–P@C) has been fabricated via a novel, simple and green precipitation route using phytic acid as the complexing agent, carbon and phosphorus sources, and glucose as the second carbon source. Phosphorus-doped carbon framework in situ forms via calcining phytic acid at a high temperature. Phosphorus doping can further enhance the electronic conductivity of carbon. The carbon framework can provide sufficient buffer space to make the SnOx particles have good dispersion. The carbon layer from glucose can prevent the direct contact between SnOx and the electrolyte to decrease the side reactions and then reinforce the structure of SnOx/C–P@C. The synergistic effect of the double carbon effectively controls the volume expansion, enhances the electronic conductivity and diffusion coefficient of Li+ ions as well as capacitive contribution ratio, and reduces the charge transfer resistance of SnOx/C–P@C. The SnOx/C–P@C-0.5 sample with the carbon content of 25.8 wt% exhibits outstanding electrochemical performance. At 0.1 A g−1, the discharge specific capacity of 776.2 mAh g−1 can be reached after 100 cycles. At 0.5 A g−1, 555.5 mAh g−1 is still delivered after 200 cycles. Moreover, the sample shows good potential practical applications in the LiNi0.5Mn1.5O4//SnOx/C–P@C-0.5 full cell. 687.9, 597.1, 510.1, 434.8 and 595.6 mAh g−1 are retained for the full cell at 0.1, 0.2, 0.5, 1 and 0.1 C, respectively. The full cell cycling for 200 cycles at 0.5 C can still light up the light-emitting diode (LED) bulbs.

Round Robin based Arbitration Mechanism for Signaling Approach based Router Architecture

In Network-on-Chip the effectiveness of the network resource allocation is demonstrated by the flow control mechanism. There are two types of flow control mechanisms: buffered and bufferless. Compared to buffered flow control methods, buffer less flow control mechanisms are easier to use, need less power, and take up less space. When there are congestion and resource conflicts, it experiences higher packet loss and packet misrouting inside the network. A good buffered control mechanism useful as it overcomes the limitations of buffer less mechanism. There are numerous buffered and bufferless flow control methods available. In this paper, signaling-based Virtual Output Queue Router Arbiter Mechanism is used to explore credit-based flow control. This mechanism worked on new concept that is “stress value”. This information is generated in the form of credit whenever any input buffer has free space. Then, using this credit data, the node's stress value is determined. Free buffer space takes precedence over stress value if it is bigger. The stress value will increase if there is less available buffer space. To handle the congestion problem, the signaling block then sends this stress value to a neighboring router. To help the arbitrator make a more accurate decision, the crediting system constantly operates in tandem with arbitration.

An enhanced approach towards improving the performance of embedding memory management units into Network-on-Chip

Network-on-Chip (NoC) initiates the design procedure of interconnection network into SoC - System-on-Chip. The current technique overcomes the drawbacks of traditional bus-based SoC, for instance, poor scalability, small-link bandwidth, and large delay. The network-on-Chip systems required minimum buffering space and low-latency requirements. Here, the FIFO buffer is utilized as a virtual channel to evade deadlock issues and thus enhances throughput. The current research focused on an enhanced toward improving Embedding-Memory-management- Units performance into Network-on-Chip. Here, the 3D NoC was considered in the study for Noc improvement and has achieved high performance. Further, A first-in-first-out (FIFO) buffer was used in NoC routers to store the data packets temporarily. Eventually, the RAM -random access memory was proposed that serves as a link between the crossbar switch and the input ports. The simulation result of the current research results in only 0 to 16 memory for data storage in a stack out of 64, with the almost empty signal being high.