Expansion Problem Research Articles

Cross-linked multifunctional binder in situ tuning solid electrolyte interface for silicon anodes in lithium ion batteries

Silicon is considered as the most promising anode material for high performance lithium-ion batteries due to its high theoretical specific capacity and low working potential. However, severe volume expansion problems existing during the process of (de)intercalation which seriously hinders its commercial progress. Binder can firmly adhere silicon and conductive agent to the current collector to maintain the integrity of the electrode structure, thereby effectively alleviating the silicon volume expansion and realizing lithium-ion batteries with high electrochemical performance. In this paper, citric acid (CA) and carboxymethyl cellulose (CMC) are adopted to construct a covalently crosslinked CA@CMC binder by an easy-to-scale-up esterification treatment. The Si@CA@CMC-1 electrode material shows an impressive initial coulombic efficiency (ICE) at 82.1% and after 510 cycles at 0.5 A/g, its specific capacity is still higher than commercial graphite. The excellent electrochemical performance of Si@CA@CMC-1 can be attributed to the ester bonds formed among CA@CMC binder and silicon particles. Importantly, by decoupling in situ EIS combining XPS at different cycles, it can be further proved that the CA@CMC binder can tune the component of SEI which provide a new-route to optimize the performance of silicon.

CoS2 confined into N-doped coal-based carbon fiber as flexible anode for high performance potassium-ion capacitor

Potassium-ion capacitors (PICs), skillfully combining the features of batteries and capacitors, hold promise in energy conversion and storage. Cobalt sulfide (CoS2) anode are promising alternatives due to its high theoretical capacity and excellent potassium storage capacity. However, severe volume changes of CoS2 anode leads to capacity decline and poor cycle stability, hindering its application in PICs. Herein, we successfully confine CoS2 nanoparticles in N-doped coal-based carbon fibers (CoS2/CF). Coal-based carbon fibers with flexible characteristic elevate the conductivity and relieve the volume expansion of CoS2. Moreover, the high content of edge nitrogen as active sites further enhances the electrochemical properties. The PICs with flexible CoS2/CF-0.8 as anode exhibits superior specific capacity (331.1 mA h g−1 after 150 cycles at 0.1 A g−1) and long cycling (214.1 mA h g−1 after 900 cycles at 1.0 A g−1). Ex-situ X-ray powder diffraction (XRD) reveal that the mechanism of CoS2/CF-0.8 anode is based on reversible intercalation and conversion reaction. Importantly, CoS2/CF-0.8||activated carbon (AC) devices shows excellent energy density (101.9 W h kg−1) and long cycling (82.23% capacity maintenance rate after 1000 cycles). This work offers insights for other materials with high theoretical capacity but volume expansion problem.

The bioindicative characteristics of the Betula pendula Roth species in the dendrocenoses of the solid household waste landfill’s influence zone

Due to the constant inflow of toxic substances into the air, soil, and groundwater, landfills not only physically occupy huge expanses of land but also have an increasing negative impact on the ecosystem and its constituent parts. As such, the research relevance is determined by the problem of landfill expansion as well as the size in Ukraine getting worse by the minute. An example of morphometric alterations in leaf indicators of the species Betula pendula Roth is used to assess the effects of the municipal solid waste landfill in Zhytomyr on the nearby dendrocenoses. The most revealing morphometric indications were identified by examining the dimensions and characteristics of the venation of leaf plates at various distances from the dump up to a radius of one kilometre. Moreover, the length of the leaf’s second vein of the second order was determined as the most stable parameter, while the difference in the lengths between the bases of the first and second veins of the second order was the most sensitive. Based on the data collected on the varying asymmetry of the leaf plates, it is concluded that variations exist in the morphometric indicators over the entire distance under investigation. These variations enable the determination of the environment within the range of “polluted” to “excessively polluted”. These findings can serve as a quick way to gauge how much of an influence landfills have on the ecosystems around them when sanitary protection strips are established, municipal waste dumps are built and outfitted, etc

Cavity expansions in two silty tailings with high degrees of saturation and a comparison to CPT results

Tailings, being mixtures of water and soil-sized particles, and sometimes air, are waste products generated by mining. They are stored on sites, often contained by embankments, forming what are known as tailings storage facilities (TSFs). Assessments of the state and strength of tailings inside a TSF may involve in situ tests, especially the cone penetration test (CPT) and occasionally the pressuremeter test (PMT). Cavity expansion theory may assist the interpretation of these tests. The coexistence of air and water in the pore space means the tailings is unsaturated and gives rise to a suction. The suction, and the extent to which air and/or water can drain through the pores, affects the cavity expansion results as well as CPT and PMT results. The cavity expansion problem is solved here considering four possible drainage conditions, constant suction, constant water mass, constant contribution of suction to the effective stress, and a constant air and water mass (closed system). It is reasoned that solutions for a closed system are relevant to the interpretations of CPTs and PMTs when < 15 % of the tailings volume is occupied by air, and that the constant effective stress condition (which is a close approximation to a constant water mass condition) is relevant when larger air volumes are present. By considering CPT data it is observed that linear proportionalities exist between effective cone penetration resistances and cavity wall pressures. The cavity expansion results are then converted to equivalent CPT results and used to construct charts which relate the normalised cone penetration resistance to the initial state parameter. The charts have use for unsaturated conditions and a variety of air volume fractions, as well as saturated conditions when the cone penetration rate is slow enough so drained conditions prevail or fast enough so that undrained conditions prevail.

Research On Management Quality of Starbucks in China's Business Expansion

This paper gives a general introduction of Starbucks including its scale in China, the changes of its sales in these years and use Five Forces Model to analyse the threats of Starbucks. From six aspects to show the potential risks of Starbucks. This essay also explores some problems Starbucks caused in expansion, leadership behaviour, personnel management, brand positioning. The main problems are the low-quality service, the ignoring of the individual management, bad performance of some workers and the broken end-up brand positioning respectively. The Maslows hierarchy of needs model is used to motivate the workers and solve the problems in expansion. The Multiple-Linkage model is divided into two parts to solve the rest problems.

How does nickel (Ni) modify two-dimensional black phosphorus to enhance its electrochemical lithium storage performance?

Recently, two-dimensional black phosphorus has shown very high potential for electrochemical lithium storage by virtue of its excellent properties. However, the defects of low electronic conductivity of two-dimensional black phosphorus itself and the tendency of volume expansion during charging and discharging also limit its development in the field of energy storage. In order to achieve better lithium storage performance, two-dimensional black phosphorus modified with Ni element was prepared by solvothermal synthesis in this study, and the high electron mobility of Ni element was used to modify the material. The synthesized material retained the morphology and properties of two-dimensional black phosphorus and its lithium storage performance were enhanced with excellent long cycling and rate performance. It had a first charge/discharge specific capacity of 651.58 mAh g−1 and 963.72 mAh g−1 at a current density of 0.1 A g−1, after which we constructed an approximate model of the material by calculation. The results of the band gap indicated that the conductivity of the material is enhanced, and the results of the lattice constant indicate that the problem of volume expansion of the system is improved. This study lays the foundation for future theoretical and practical applications of two-dimensional black phosphorus.

Preparation of TiO2/nitrogen-doped CNF composites as high-performance lithium-ion battery anodes by electrospinning

In this paper, nitrogen-doped carbon nanofibers encapsulated titanium dioxide nanoparticles (TiO2/NCNF) anode materials were prepared by electrospinning. Through the construction of heterojunctions, the inherent low ionic conductivity and electronic conductivity of transition metal oxides are overcome. Nitrogen-doped carbon nanofibers have the advantages of large active surface area, strong deformation stress and short ion diffusion path. In addition, nitrogen-doped carbon nanofibers can not only improve the storage capacity of lithium ions by introducing defects through heteroatom doping, but also further improve the electronic conductivity of carbon nanofibers. By encapsulating nanoparticles with nanofibers, the volume expansion and agglomeration problems during the material cycle are slowed down, and the electrochemical performance of the material is greatly improved. The TiO2/NCNF anode material still has a specific capacity of 386.1 mAh /g after 100 cycles at a current density of 0.1 A /g, and can maintain a specific capacity of 206.63 mAh /g at a high current density of 2 A /g.

Characterization and impact analysis of freezing and expansion disease of roadbed in seasonal freezing zone: A case of heavy railroads

The freezing and expansion diseases of railroad roadbeds are prevalent in areas that experience seasonal freezing. This study aims to investigate the features of the freezing and expansion mechanism of seasonal frozen railroad roadbeds and the effects of the freezing and expansion diseases on the roadbeds. This article presents a study of the Shuo-Huang Heavy Duty Railway. Initially, on-site monitoring tests were conducted to analyze the roadbed temperature, water content and deformations due to freezing. Through these tests, the pattern of development of the roadbed freezing and swelling was understood, and the effect of this on the vibration response of the roadbed was investigated. Subsequently, load-free freezing tests were performed to investigate the freezing and expansion features of the roadbed. Through on-site monitoring, it has been determined that the seasonal freezing layer is approximately 0.5 ​m deep. The depth of the frozen expansion on both sides of the road shows clear differences. The frozen and expansion disease significantly amplifies the vibration acceleration of the roadbed, with a tendency towards low-frequency and high-amplitude vibrations. Through indoor testing, we compared the deformation of frozen specimens and their final freeze and expansion rates at different cold-end temperatures and various initial moisture content levels. We find that the initial moisture content has a greater impact on specimen freezing and expansion. The findings in this paper can be used as a reference for researching and addressing roadbed freezing and expansion problems.

Study on preparation technology of large bimetal composite wear-resistant elbow

Large - scale bimetal composite wear-resistant elbow was fabricated by lost - die casting,the non-working layer of the outer wall of the bend was made of 16Mn steel pipe, and the inner working layer was made of high chromium cast iron. This paper introduced the preparation technology and method of elbow from the aspects of material composition selection, melting process, lost mold casting process and heat treatment process, analyzed and solved the problems of box collapse and box expansion in the casting process. The wear test shown that the wear resistance of bimetallic composite elbow was twice that of 16Mn material elbow. The service life of the composite elbow was 2~3 times that of the original single material elbow.

A heuristic tomato-bunch harvest manipulator path planning method based on a 3D-CNN-based position posture map and rapidly-exploring random tree

The environment of tomato bunches is complex, and the fruit volume is relatively large, so manipulator picking-harvest motion planning should consider not only how to pick, but also how to avoid obstacles after picking tomato bunches and harvesting them from the complex environment, which puts forward strict requirements for picking-harvest motion performance. However, existing sampling-based algorithms still have problems of blind expansion and low efficiency. To solve these problems, a heuristic tomato-bunch harvest manipulator path planning method based on a 3D-CNN (convolution neural network)-based position posture map (PPM) and rapidly-exploring random tree (RRT) is proposed in this paper. This method comprehensively considers the sampling effectiveness of the whole process of picking and harvesting, search speed, path cost and manipulability of the manipulator, combining a sampling-based path planning algorithm and deep learning framework. The method utilizes CNN and FCN(Fully Connected Neural Networks) for generating a heuristic cost map where each voxel has a cost-to-go value toward the target and an optimal target posture value to guide the expansion tree. In addition, the sampling space of obstacle avoidance planning is reduced by a spatial partition method, and the difficulty caused by the increase in the volume of the end-effector clamping fruit is solved by prioritizing the planning of the fruit harvest path and then planning the picking path. On the basis of the above research, a large number of harvest experiments have verified the effectiveness of the proposed algorithm. Research and experimental results show that, based on the PPM-RRT algorithm, the picking-harvest time of a single tomato bunch is 13 s, and the success rate is close to 100%. Compared with state-of-the-art sampling algorithms, the planning time is reduced by more than 70%, the path length is reduced by more than 24%, and the manipulability of the manipulator is increased by 38.9%. The proposed path planning method is effective in complex environments.

Sustainable and Resilient Capacity Expansion Planning for Chemical Processing Industry: A Bi-Objective Approach

According to United Nations reports, the worldwide population is expected to reach around 9.6 billion by 2050. This forecast emphasizes the critical role of energy and raw materials that are needed to meet the tremendous demand for goods. Consequently, firms feel pressured to establish sustainable and resilient strategic plans to acquire new process technologies and expand their capacity on time. These decisions are made at the highest management level, supported by a set of capacity expansion portfolios, to improve their competitiveness, especially in capital-intensive industries such as chemical processing. This paper investigates the sustainable and resilient capacity expansion problem for such industries within a long-term horizon. The main objective is to develop a holistic capacity expansion planning framework that fits the chemical processing industries and can be used to generate resilient scenarios while enhancing their sustainability measures. To this end, a bi-objective mixed-integer programming model was developed to solve the sustainability–resilience–profitability dilemma. The results showed a controversial relationship between the profitability of capacity expansion investments and a company’s commitment to sustainability and resilience. Furthermore, capacity expansion decisions were shown to primarily depend on the importance assigned to maximize profit as a managerial choice. However, there is no clear trend in sustainability preferences based on the sustainability weighting choice.

Macro-encapsulation of metallic phase change materials with sacrificial density less than 3.5 % for medium-temperature heat storage

To solve the problems of volume thermal expansion and high chemical activity of metallic phase change materials (PCMs), this paper successfully prepared millimeter/centimeter-size durable Bi@Void@Kaolin macrocapsules. Fortunately, carbon powder clusters from the thermal decomposition of adhesive CMC gathered on the core PCMs, cleverly adding a reducing atmosphere into the capsules. In particular, the buffer voids of macrocapsules were created from the pores and gaps between the accumulated Bi powders, and the method of improving the bulk density of powder cores as core precursors by the cold isostatic pressing (CIP) technology solves the problem of excessive cavity volume. Thermal analysis indicates that after CIP treatment, the heat storage density of the Bi@Kaolin macrocapsule with the unpressurized powder core volume accounting for 50% can be increased by 18.4%–275.0 J/cm3, which is about 2.5 times the heat storage density of the common medium-temperature heat storage materials - concrete and NaCl, under the working temperature range of 240–300 °C. Solid-liquid PCMs need to sacrifice their density in exchange for the necessary cavity volume, therefore the “actual volumetric heat storage density” of PCMs should be specified. The results show that the proportion of sacrificial density of Bi PCM (i.e. the cavity rate of Bi-based macrocapsule) can reach the optimal value of 3.5%, its actual volumetric heat storage density can reach 558.9 J/cm3 at 240–300 °C. Surprisingly, all the Bi@Kaolin macrocapsules showed excellent cycling durability and thermal stability during 500 cycles under air atmosphere and subsequent 24 h overload-temperature oxidation tests.

Transmission line planning using global best artificial bee colony method

Introduction. Network expansion, substation planning, generating expansion planning, and load forecasting are all aspects of modern power system planning. The aim of this work is to solve network planning considering both future demand and all equality and inequality constraints. The transmission network design problem for the 6-bus system is considered and addressed using the Global Best Artificial Bee Colony (GABC) method in this research. The program is written in the Matrix Laboratory in MATLAB environment using the proposed methodology. Novelty of the work consist in considering the behavior of bees to find food source in most optimized way in nature with feature of user based accuracy selection and speed of execution selection on any scale of the system to solve Transmission Lines Expansion Problem (TLEP). The proposed method is implemented on nonlinear mathematical function and TLEP function. When demand grows, the program output optimally distributes new links between new generation buses and old buses, determines the overall minimum cost of those links, and determines if those linkages should meet power system limits. Originality of the proposed method is that it eliminated the need of load shedding while planning the future demand with GABC method. Results are validated using load flow analysis in electrical transient analyzer program, demonstrating that artificial intelligence approaches are accurate and particularly effective in non-linear transmission network planning challenges. Practical value of the program is that it can use to execute cost oriented complex transmission planning decision.

Solvent modulation strategy for Sb-based anode to achieve stable potassium storage

High-concentration electrolyte (HCE) and localized high-concentration electrolyte (LHCE) strategies have been successfully developed for potassium-ion batteries (PIBs) to address the interface incompatibility issue, especially for the high-theoretical-capacity antimony (Sb)-based alloy-typed anode suffering from the drastic volume expansion problem. However, the high costs along with special solvents for these electrolytes significantly limits their widespread applications in PIBs. Herein, a new dilute electrolyte of 1 M KFSI in a mixed solvent of ethylene carbonate (EC) and 1, 2-dimethoxyethane (DME) (1:1 v/v) is developed to stabilize the K-storage kinetics of Sb anodes. The mixed solvent of common ester and ether promotes the formation of stable K+-EC solvent pair and thus generates a robust solid-electrolyte-interphase (SEI) for stable K-storage. As a result, the fabricated Sb@NC anode exhibits a stable capacity of 376 mAh/g after 100 cycles at 100 mA g−1, which is comparable to that in the HCE of 5 M KFSI/DME. These results demonstrated that low-cost and high-compatibility electrolytes for alloy-typed anodes can be achieved via rational design of the solvation structures for dilute electrolytes, resulting into stable K-storage properties and huge prospects of commercialized applications.

A new approach to flatness, horizon and late-time accelerating expansion problems on the basis of Mach’s principle

Based on the idea that the components of a cosmological metric may be determined by the total gravitational potential of the universe, the scalar field $\phi=1/G$ in the Jordan-Brans-Dicke (JBD) theory is introduced as evolving with the inverse square of the scale factor. Since the gravitational potential is related to the field $\phi$ resulting from Mach's principle and depends on time due to the expansion of space, the temporal evolution of the field should be in accord with the evolution of time and space intervals in the metric tensor. For the same reason, the time dependence of the field makes these comoving intervals relative for different points on the time axis. Thus, it is shown that introduction of the cosmic gravitational potential as a time dependent scalar field proportional to $1/a^2$ may resolve the flatness, the horizon and the late-time accelerating expansion problems of the standard model of cosmology. The luminosity distance vs redshift data of Type Ia supernovae is in agreement with this approach.

Binder-Free CoMn2O4 Nanoflower Particles/Graphene/Carbon Nanotube Composite Film for a High-Performance Lithium-Ion Battery

Manganese-based bimetallic oxides show a high theoretical specific capacity, making them a potential next-generation lithium-ion battery anode material. However, as with metal oxide anode materials, aggregation, volume expansion, and poor conductivity are the main obstacles. In this manuscript, flexible CoMn2O4/graphene/carbon nanotube films were successfully prepared through a facile filtration strategy and a subsequent thermal treatment process. When used as anodes for lithium batteries, these films can be pressed onto nickel foam without other conductive additives and binders, which simplifies the manufacturing process. When used as an anode in the lithium-ion battery, CoMn2O4/GR/CNT film exhibits a high discharge capacity of 881 mAh g−1 after 55 cycles. This value is ~2 times higher than the discharge capacity of CoMn2O4. The three-dimensional GR/CNT carrier effectively dispersed CoMn2O4, preventing its aggregation and alleviating the problem of volume expansion.

The role of fast-acting energy storage for contingency grid support in the transmission planning

This paper investigates the role of fast-acting energy storage systems in transmission expansion planning, by allowing higher transfers through the network during normal operation. This is achieved by considering the ability of energy storage systems to provide real and reactive power reserves after forced single-circuit outages to prevent line overloading and voltage level violations in post-contingency states, and by applying the corrective N−1 security criterion. A computational tool is presented to solve the multi-year transmission expansion problem with multiple scenarios of availability of renewable energy sources. The model is solved using the FICO Xpress software. The 2022–2037 Chilean transmission expansion plan is used as a case study, given the high need for flexibility to integrate 29.5 GW of new solar and wind generation capacity several hundred kilometers from its load center, with a system peak demand of 16.5 GW. The results obtained show that fast-acting energy storage systems reduce the cost of the investment plan by USD 712 million (-18%) mainly because it requires 5 GWh less of conventional storage capacity (-19%), allowing the system operator to increase the usage of the existing transmission network, and providing the central planner with a deferral option for the construction of new transmission lines.

Spherical cavity expansion method dependent on strain, strain rate, and temperature

This paper presents a spherical cavity expansion method based on the self-similar field considering dynamic hardening, which includes plastic strain, plastic strain rate, and temperature for an infinite compressible medium under J2 plasticity. This study proposes an approach based on the gradients of plastic strain and temperature under self-similarity transformation to deal with dynamic hardening models such as the Johnson-Cook (JC) and the modified Johnson-Cook (mJC) models. A theoretical model shows that the effective and radial stresses are reduced near the cavity surface and increased away from the cavity under the mutual influence of hardening and thermal softening. The JC hardening model is used to analyze the behavior of the cavity expansion for AISI 4340 steel. The proposed theoretical model was validated by comparing the result of the explicit finite element method (FEM). This study discusses the behavior of the expanding cavity problem for thermal softening and strain rate sensitivities. In addition, rigid penetration problems are simulated to analyze the application of the presented method. FEM and the proposed cavity expansion method were compared with the penetration depth of AA6061-T651 target using the mJC hardening model for a hemispherical-nosed penetrator. A comparison is made for the performance of the penetration depth with an ogive-nose projectile for AA7075-T651 and AA6061-T651 materials using the mJC hardening model. This study concludes that the proposed method can be applied without modifying the hardening models to spherical cavity expansion problems that involve dynamic hardening models dependent on strain, strain rate, and temperature under adiabatic heat.

Theoretical determination of the expansion forces of the technological cavity in the soil by wedge-prismatic and conical-cylindrical working bodies

&#x0D; Problem. The article deals with the problem of expansion of the technological cavity in the soil (TPG), previously obtained by the method of controlled static piercing, for the laying of underground linear extension objects (LPO) of urban communication networks. Group laying of communications in one cavity requires large holes, which in turn leads to a significant increase in the workforce and dimensions of work equipment. The only way out of such a situation is the use of working bodies (RO) of wedge-prismatic form, gradual expansion of the hole in several stages and change of soil moisture in the walls of the hole cavity. Goal. The main goal is to create a methodology for engineering calculation of the parameters of the wedge-prismatic working bodies and to determine the static expansion efforts of the TPG based on the known initial data on the soil and the shape of the RO. Methodology. The study is based on the theory of the invariance of soil mass before and after piercing. In the process of expanding the TPG to the required size, the density of the soil medium changes from its natural value to a solid state, after which the soil simply moves to a certain distance from the axis of the cavity, compacting the neighboring massifs. Results. The hypothesis of the interaction of wedge-prismatic tips with the soil during static puncture is substantiated based on the determined law of soil density change along the thickness of the wedge-prismatic tip. Originality. The theoretical dependences for determining the rational parameters of the RO of wedge-prismatic form, the resistance of the sequential expansion of the TPG for the LPO after the starting passage of the leading hole, or the cavities of the primary expansion were obtained. Practical value. A method of determining the penetration force of the TPG for LPO after the leading pass is proposed, taking into account the elastic (reverse) deformations of the soil, its moisture, the shape of the RO, and the characteristics of the power equipment, as the difference between the full and pilot resistance of the soil puncture, as well as recommendations on the possibility of reduction o these forces by changing the shape of work equipment or soil moisture.&#x0D;

Role of moderate strain engineering in Nickel Sulfide anode for advanced sodium-ion batteries

The lattice strain engineering of sodium storage materials is of great significance for developing reliable sodium-ion batteries (SIBs). Lattice strain engineering controls the structural evolution during sodium ion insertion/extraction and minimizes the aggregation of active material and volume expansion during cycling. Herein, the ball milling technique is used to tune the lattice strain of NiS nanocomposite, which was later employed as anode material in SIBs. The structurally tuned anode exhibits high sodiation capacity, good rate capability (495.7 mAh g−1 at 0.2 A g−1, 383.2 mAhg−1 at 15 Ag−1), and exceptional cycling performance (16,000 cycles at 5 A g−1). Significantly, introducing a considerable amount of moderate strain into the structure by the ball milling technique, researchers can solve the problem of structure instability, volume expansion, and high-capacity loss of the electrode materials during repeated cycling. Therefore, lattice strain engineering using ball milling is a potential approach that may open the door to more sustainable and functional SIBs.